JP7618436B2 - Reversible thermochromic composition and reversible thermochromic microcapsule pigment containing the same - Google Patents

Description

The present invention relates to a reversible thermochromic composition and a reversible thermochromic microcapsule pigment encapsulating the same. The present invention relates to a reversible thermochromic composition that loses color when heated and develops color when cooled, and a reversible thermochromic microcapsule pigment encapsulating the same.

Several proposals have been disclosed in the past regarding reversible thermochromic compositions comprising a compatible solution of an electron-donating color-forming organic compound, an electron-accepting compound, and a reaction medium that reversibly induces an electron donor-acceptor reaction in a specific temperature range, and reversible thermochromic microcapsule pigments encapsulating the same (for example, see Patent Documents 1 to 5).
Examples of the electron-accepting compound contained in the reversible thermochromic composition include a compound having an active proton, a pseudo-acidic compound group (a compound group that is not an acid but acts as an acid in the composition to cause the electron-donating color-forming organic compound to develop color), and a compound group having an electron vacancy.

Japanese Patent Application Publication No. 7-11242 JP 2002-53853 A JP 2010-106052 A JP 2012-229294 A JP 2013-10810 A

The present invention has been carried out by investigating the electron-accepting compound (b) that is applied to a reversible thermochromic composition comprising (a) an electron-donating organic color-forming compound, (b) an electron-accepting compound, and (c) a reaction medium that reversibly induces an electron transfer reaction between the components (a) and (b) in a specific temperature range. As a result, it has been found that the use of a specific compound can produce a reversible thermochromic function.

（式（１）中、Ｒ_１～Ｒ_５はそれぞれ独立に水素原子、ハロゲン原子、ニトロ基、アミノ基、アルキル基、アルコキシ基、アリールオキシ基、アルキルカルボニルオキシ基、アリールカルボニルオキシ基、アルキルカルボニルアミノ基、アリールカルボニルアミノ基、アルキルスルホニルアミノ基、アリールスルホニルアミノ基、モノアルキルアミノ基、ジアルキルアミノ基、アリールアミノ基を表す。）
更には、前記一般式（１）の化合物が一般式（２）で表される化合物であること、

（式（２）中、Ｒ_３は水素原子、ハロゲン原子、ニトロ基、アミノ基、アルキル基、アルコキシ基、アリールオキシ基、アルキルカルボニルオキシ基、アリールカルボニルオキシ基、アルキルカルボニルアミノ基、アリールカルボニルアミノ基、アルキルスルホニルアミノ基、アリールスルホニルアミノ基、モノアルキルアミノ基、ジアルキルアミノ基、アリールアミノ基を表す。）
式（２）において、Ｒ_３はフッ素原子、塩素原子、臭素原子、炭素数１乃至１２のアルキル基、炭素数１乃至１２のアルコキシ基、炭素数６乃至１２のアリールオキシ基のいずれかであること、前記（イ）成分１質量部に対して、（ロ）成分０．１～１００質量部、（ハ）成分５～２００質量部の範囲で含有されてなること、前記（イ）成分１質量部に対して、（ロ）成分０．１～５０質量部、（ハ）成分５～１００質量部の範囲で含有されてなること等を要件とする。
更には、前記可逆熱変色性組成物を内包してなる可逆熱変色性マイクロカプセル顔料、前記可逆熱変色性マイクロカプセル顔料と、ビヒクルとを含んでなる可逆熱変色性液状組成物、前記可逆熱変色性マイクロカプセル顔料と、賦形剤とを含んでなる可逆熱変色性塗布用固形成形体、前記可逆熱変色性マイクロカプセル顔料と成形用樹脂とを含んでなる、可逆熱変色性成形用樹脂組成物、支持体と、前記可逆熱変色性マイクロカプセル顔料を含んでなる可逆熱変色層とを具備してなる、可逆熱変色性積層体等を要件とする。 The present invention relates to a reversible thermochromic composition comprising (a) an electron-donating organic color-forming compound, (b) a compound represented by formula (1) as an electron-accepting compound, and (c) a reaction medium that reversibly induces an electron donor-acceptor reaction between the components (a) and (b) in a specific temperature range.

(In formula (1), R ₁ to R ₅ each independently represent a hydrogen atom, a halogen atom, a nitro group, an amino group, an alkyl group, an alkoxy group, an aryloxy group, an alkylcarbonyloxy group, an arylcarbonyloxy group, an alkylcarbonylamino group, an arylcarbonylamino group, an alkylsulfonylamino group, an arylsulfonylamino group, a monoalkylamino group, a dialkylamino group, or an arylamino group.)
Furthermore, the compound of the general formula (1) is a compound represented by general formula (2),

(In formula (2), _R3 represents a hydrogen atom, a halogen atom, a nitro group, an amino group, an alkyl group, an alkoxy group, an aryloxy group, an alkylcarbonyloxy group, an arylcarbonyloxy group, an alkylcarbonylamino group, an arylcarbonylamino group, an alkylsulfonylamino group, an arylsulfonylamino group, a monoalkylamino group, a dialkylamino group, or an arylamino group.)
In formula (2), _R3 is any one of a fluorine atom, a chlorine atom, a bromine atom, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, and an aryloxy group having 6 to 12 carbon atoms; the components (b) and (c) are contained in ranges of 0.1 to 100 parts by mass and 5 to 200 parts by mass, respectively, of the component (a); and the components (b) and (c) are contained in ranges of 0.1 to 50 parts by mass and 5 to 100 parts by mass, respectively, of the component (a).
Further requirements include a reversible thermochromic microcapsule pigment encapsulating the reversible thermochromic composition, a reversible thermochromic liquid composition comprising the reversible thermochromic microcapsule pigment and a vehicle, a reversible thermochromic solid molding for coating comprising the reversible thermochromic microcapsule pigment and an excipient, a reversible thermochromic molding resin composition comprising the reversible thermochromic microcapsule pigment and a molding resin, and a reversible thermochromic laminate comprising a support and a reversible thermochromic layer comprising the reversible thermochromic microcapsule pigment.

The present invention uses a specific compound as an electron-accepting compound, which satisfies the electron donor/acceptor reaction with an electron-donor organic color-developing compound, and further (c) mixes the composition with a reaction medium that reversibly induces the electron donor/acceptor reaction by the components (a) and (b) in a specific temperature range, thereby making it possible to obtain a reversible thermochromic composition that can fully exhibit reversible thermochromic function, and a reversible thermochromic microcapsule pigment that encapsulates the composition.

1 is a graph illustrating hysteresis characteristics in a color density-temperature curve of a heat-discolorable, reversible thermochromic composition. 1 is a graph illustrating the hysteresis characteristic in a color density-temperature curve of a heat-discolorable, reversible thermochromic composition having color memory properties.

The reversible thermochromic composition of the present invention includes a reversible thermochromic composition of a heat-discolorable type (discolored by heating and colored by cooling) that contains at least three essential components: (a) an electron-donating color-forming organic compound, (b) an electron-accepting compound, and (c) a reaction medium that determines the temperature at which the color-forming reaction of components (a) and (b) occurs.
The reversible thermochromic composition may be a reversible thermochromic composition of the type described in JP-B-51-44706, JP-B-51-44707, JP-B-1-29398, etc., which changes color around a certain temperature (discoloration point), exhibits a discolored state in a temperature range above the high-temperature discoloration point, and exhibits a colored state in a temperature range below the low-temperature discoloration point, and only one of the two states exists in the room temperature range, and the other state is maintained while the heat or cold required to express that state is applied, but returns to the state exhibited in the room temperature range when the application of heat or cold is removed. The hysteresis width (ΔH) is relatively small (ΔH = 1 to 7 ° C.), and a reversible thermochromic composition of the type that discolors when heated and develops color when cooled can be used (see FIG. 1).

In addition, the ink exhibits a large hysteresis width (ΔH=8 to 70° C.) as described in JP-B-4-17154, JP-A-7-179777, JP-A-7-33997, JP-A-8-39936, JP-A-2005-1369, etc., and the shape of the curve plotting the change in color density due to temperature change follows a path that is significantly different when the temperature is increased from a lower temperature side than the color change temperature range from that when the temperature is decreased from a higher temperature side than the color change temperature range. The colored state in a temperature range below the complete color development temperature _t1 or the decolored state in a high temperature range above the complete decolorization temperature _t4 is different from the color development start temperature _t2 to the decolorization start temperature t4. It is also possible to use a reversible thermochromic composition of the heat-discoloring type (discolored by heating and colored by cooling) having color memory in a temperature range between 0.1 and 0.3 (substantially two-phase maintaining temperature range) (see FIG. ₂ ).

Each of components (a), (b) and (c) will be specifically described below.
Component (A), that is, the electron-donating organic color-forming compound, is a component that determines the color and is a compound that develops color by donating electrons to component (B), which is a color developer.
Examples of the electron-donating organic color-developing compound include phthalide compounds, fluoran compounds, styrinquinoline compounds, diazarhodamine lactone compounds, pyridine compounds, quinazoline compounds, and bisquinazoline compounds. Among these, phthalide compounds and fluoran compounds are preferred.
Examples of the phthalide compound include diphenylmethane phthalide compounds, phenylindolyl phthalide compounds, indolyl phthalide compounds, diphenylmethane azaphthalide compounds, phenylindolyl azaphthalide compounds, and derivatives thereof. Among these, phenylindolyl azaphthalide compounds and derivatives thereof are preferred.
Examples of the fluoran compound include aminofluoran compounds, alkoxyfluoran compounds, and derivatives thereof.
Examples of these compounds are given below.
3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide,
3-(4-diethylaminophenyl)-3-(1-ethyl-2-methylindol-3-yl)phthalide,
3,3-bis(1-n-butyl-2-methylindol-3-yl)phthalide,
3,3-bis(2-ethoxy-4-diethylaminophenyl)-4-azaphthalide,
3-(2-ethoxy-4-diethylaminophenyl)-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide,
3-(2-hexyloxy-4-diethylaminophenyl)-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide,
3-[2-ethoxy-4-(N-ethylanilino)phenyl]-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide,
3-(2-acetamido-4-diethylaminophenyl)-3-(1-propylindol-3-yl)-4-azaphthalide,
3,6-bis(diphenylamino)fluoran,
3,6-dimethoxyfluoran,
3,6-di-n-butoxyfluoran,
2-methyl-6-(N-ethyl-N-p-tolylamino)fluoran,
3-chloro-6-cyclohexylaminofluoran,
2-methyl-6-cyclohexylaminofluoran,
2-(2-chloroamino)-6-dibutylaminofluoran,
2-(2-chloroanilino)-6-di-n-butylaminofluoran,
2-(3-trifluoromethylanilino)-6-diethylaminofluoran,
2-(3-trifluoromethylanilino)-6-dipentylaminofluoran,
2-(dibenzylamino)-6-diethylaminofluoran,
2-(N-methylanilino)-6-(N-ethyl-N-p-tolylamino)fluoran,
1,3-dimethyl-6-diethylaminofluoran,
2-chloro-3-methyl-6-diethylaminofluoran,
2-anilino-3-methyl-6-diethylaminofluoran,
2-anilino-3-methoxy-6-diethylaminofluoran,
2-anilino-3-methyl-6-di-n-butylaminofluoran,
2-anilino-3-methoxy-6-di-n-butylaminofluoran,
2-xylidino-3-methyl-6-diethylaminofluoran,
2-anilino-3-methyl-6-(N-ethyl-N-p-tolylamino)fluoran,
1,2-Benz-6-diethylaminofluoran,
1,2-Benz-6-(N-ethyl-N-isobutylamino)fluoran,
1,2-Benz-6-(N-ethyl-N-isoamylamino)fluoran,
2-(3-methoxy-4-dodecoxystyryl)quinoline,
spiro[5H-(1)benzopyrano(2,3-d)pyrimidin-5,1'(3'H)isobenzofuran]-3'-one, 2-(diethylamino)-8-(diethylamino)-4-methyl,
spiro[5H-(1)benzopyrano(2,3-d)pyrimidin-5,1'(3'H)isobenzofuran]-3'-one, 2-(di-n-butylamino)-8-(di-n-butylamino)-4-methyl,
spiro[5H-(1)benzopyrano(2,3-d)pyrimidin-5,1'(3'H)isobenzofuran]-3'-one, 2-(di-n-butylamino)-8-(diethylamino)-4-methyl,
spiro[5H-(1)benzopyrano(2,3-d)pyrimidin-5,1'(3'H)isobenzofuran]-3'-one, 2-(di-n-butylamino)-8-(N-ethyl-N-i-amylamino)-4-methyl,
spiro[5H-(1)benzopyrano(2,3-d)pyrimidin-5,1'(3'H)isobenzofuran]-3'-one, 2-(dibutylamino)-8-(dipentylamino)-4-methyl,
4,5,6,7-tetrachloro-3-[4-(dimethylamino)-2-methoxyphenyl]-3-(1-butyl-2-methyl-1H-indol-3-yl)-1(3H)-isobenzofuranone,
4,5,6,7-tetrachloro-3-[4-(diethylamino)-2-ethoxyphenyl]-3-(1-ethyl-2-methyl-1H-indol-3-yl)-1(3H)-isobenzofuranone,
4,5,6,7-tetrachloro-3-[4-(diethylamino)-2-ethoxyphenyl]-3-(1-pentyl-2-methyl-1H-indol-3-yl)-1(3H)-isobenzofuranone,
4,5,6,7-tetrachloro-3-[4-(diethylamino)-2-methylphenyl]-3-(1-ethyl-2-methyl-1H-indol-3-yl)-1(3H)-isobenzofuranone,
3',6'-bis[phenyl(2-methylphenyl)amino]-spiro[isobenzofuran-1(3H),9'-[9H]xanthene]-3-one,
3',6'-bis[phenyl(3-methylphenyl)amino]-spiro[isobenzofuran-1(3H),9'-[9H]xanthene]-3-one,
3',6'-bis[phenyl(3-ethylphenyl)amino]-spiro[isobenzofuran-1(3H),9'-[9H]xanthene]-3-one,
2,6-bis(2'-ethyloxyphenyl)-4-(4'-dimethylaminophenyl)pyridine,
2,6-bis(2',4'-diethyloxyphenyl)-4-(4'-dimethylaminophenyl)pyridine,
2-(4'-dimethylaminophenyl)-4-methoxy-quinazoline,
4,4'-(ethylenedioxy)-bis[2-(4-diethylaminophenyl)quinazoline]
etc. can be mentioned.
In addition to the above-mentioned compounds having a substituent on the phenyl group forming the xanthene ring, the fluorans may also be compounds that have a substituent on the phenyl group forming the xanthene ring and also have a substituent (e.g., an alkyl group such as a methyl group, or a halogen atom such as a chloro group) on the phenyl group forming the lactone ring, and that exhibit a blue or black color.

（式（１）中、Ｒ_１～Ｒ_５はそれぞれ独立に水素原子、ハロゲン原子、ニトロ基、アミノ基、アルキル基、アルコキシ基、アリールオキシ基、アルキルカルボニルオキシ基、アリールカルボニルオキシ基、アルキルカルボニルアミノ基、アリールカルボニルアミノ基、アルキルスルホニルアミノ基、アリールスルホニルアミノ基、モノアルキルアミノ基、ジアルキルアミノ基、アリールアミノ基を表す。）
式（１）のＲ_１～Ｒ_５におけるハロゲン原子として、フッ素原子、塩素原子、臭素原子が挙げられ、フッ素原子、塩素原子が好ましい。 Component (b), that is, an electron accepting compound, is a compound that accepts electrons from component (a) and functions as a developer for component (a).
As the component (b), a non-phenolic electron accepting compound (developer) represented by the formula (1) is used.

(In formula (1), R ₁ to R ₅ each independently represent a hydrogen atom, a halogen atom, a nitro group, an amino group, an alkyl group, an alkoxy group, an aryloxy group, an alkylcarbonyloxy group, an arylcarbonyloxy group, an alkylcarbonylamino group, an arylcarbonylamino group, an alkylsulfonylamino group, an arylsulfonylamino group, a monoalkylamino group, a dialkylamino group, or an arylamino group.)
Examples of the halogen atom in R ₁ to R ₅ in the formula (1) include a fluorine atom, a chlorine atom and a bromine atom, with a fluorine atom and a chlorine atom being preferred.

Furthermore, examples of the alkyl group in R ₁ to R ₅ in formula (1) include linear, branched, and cyclic alkyl groups, and the number of carbon atoms is usually C1 to C12, preferably C1 to C8, and more preferably C1 to C6. Specific examples of the alkyl group include linear alkyl groups such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-octyl, n-nonyl, n-decyl, n-undecyl, and n-dodecyl, branched alkyl groups such as isopropyl, isobutyl, sec-butyl, t-butyl, isopentyl, isohexyl, and isooctyl, and cyclic alkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl.

The alkoxy group for R ₁ to R ₅ in formula (1) includes linear, branched or cyclic alkoxy groups, and generally has from C1 to C12 carbon atoms, preferably from C2 to C8 carbon atoms, and more preferably from C2 to C6 carbon atoms. Specific examples of alkoxy groups include linear alkoxy groups such as methoxy, ethoxy, n-propoxy, n-butoxy, n-pentoxy, n-hexyloxy, n-heptoxy, n-octyloxy, n-nonyloxy, and n-decyloxy; branched alkoxy groups such as isopropoxy, isobutoxy, sec-butoxy, t-butoxy, isoamyloxy, t-amyloxy, isohexyloxy, t-hexyloxy, isoheptoxy, t-heptoxy, isooctyloxy, t-octyloxy, 2-ethylhexyloxy, isononyloxy, and isodecyloxy; and cyclic alkoxy groups such as cyclopropoxy, cyclobutoxy, cyclopentoxy, cyclohexyloxy, and cycloheptoxy.

The aryloxy group in R ₁ to R ₅ of formula (1) includes a C6 to C12 aryloxy group, such as phenoxy, naphthyloxy, and biphenyloxy.

Examples of the alkylcarbonyloxy group for R ₁ to R ₅ in formula (1) include linear, branched or cyclic alkylcarbonyloxy groups having 1 to 10 carbonyl groups, such as linear alkylcarbonyloxy groups such as methylcarbonyloxy, ethylcarbonyloxy, n-propylcarbonyloxy, n-butylcarbonyloxy, n-pentylcarbonyloxy, n-hexylcarbonyloxy, n-heptylcarbonyloxy, n-octylcarbonyloxy, n-nonylcarbonyloxy and n-decylcarbonyloxy; isopropylcarbonyloxy, isobutylcarbonyloxy, sec-butylcarbonyloxy, t-butylcarbonyloxy and isoamidocarbonyloxy; Examples of branched chain alkylcarbonyloxy groups include branched chain alkylcarbonyloxy groups such as arylcarbonyloxy, t-amylcarbonyloxy, isohexylcarbonyloxy, t-hexylcarbonyloxy, isoheptylcarbonyloxy, t-heptylcarbonyloxy, isooctylcarbonyloxy, t-octylcarbonyloxy, 2-ethylhexylcarbonyloxy, isononylcarbonyloxy, and isodecylcarbonyloxy; and cyclic alkylcarbonyloxy groups such as cyclopropylcarbonyloxy, cyclobutylcarbonyloxy, cyclopentylcarbonyloxy, cyclohexylcarbonyloxy, and cycloheptylcarbonyloxy.

The arylcarbonyloxy group in R ₁ to R ₅ of the formula (1) includes a C6 to C12 arylcarbonyloxy group, such as phenylcarbonyloxy, naphthylcarbonyloxy, and biphenylcarbonyloxy.

Examples of the alkylcarbonylamino group in R ₁ to R ₅ of formula (1) include linear, branched or cyclic alkylcarbonylamino groups having 1 to 10 carbonyl groups, such as linear alkylcarbonylamino groups such as methylcarbonylamino, ethylcarbonylamino, n-propylcarbonylamino, n-butylcarbonylamino, n-pentylcarbonylamino, n-hexylcarbonylamino, n-heptylcarbonylamino, n-octylcarbonylamino, n-nonylcarbonylamino and n-decylcarbonylamino, isopropylcarbonylamino, isobutylcarbonylamino, sec-butylcarbonylamino, t-butylcarbonylamino and isoamino. branched chain alkylcarbonylamino groups such as arylcarbonylamino, t-amylcarbonylamino, isohexylcarbonylamino, t-hexylcarbonylamino, isoheptylcarbonylamino, t-heptylcarbonylamino, isooctylcarbonylamino, t-octylcarbonylamino, 2-ethylhexylcarbonylamino, isononylcarbonylamino, and isodecylcarbonylamino; and cyclic alkylcarbonylamino groups such as cyclopropylcarbonylamino, cyclobutylcarbonylamino, cyclopentylcarbonylamino, cyclohexylcarbonylamino, and cycloheptylcarbonylamino.

The arylcarbonylamino group in R ₁ to R ₅ of the formula (1) includes a C6 to C12 arylcarbonylamino group, such as phenylcarbonylamino, naphthylcarbonylamino, and biphenylcarbonylamino.

The alkylsulfonylamino group in R ₁ to R ₅ of formula (1) includes a C1 to C10 linear, branched or cyclic alkylsulfonylamino group, such as linear alkylsulfonylamino groups such as methylsulfonylamino, ethylsulfonylamino, n-propylsulfonylamino, n-butylsulfonylamino, n-pentylsulfonylamino, n-hexylsulfonylamino, n-heptylsulfonylamino, n-octylsulfonylamino, n-nonylsulfonylamino and n-decylsulfonylamino; isopropylsulfonylamino, isobutylsulfonylamino, sec-butylsulfonylamino, t-butylsulfonylamino, isobutylsulfonylamino, sec-butylsulfonylamino, t-butylsulfonylamino, isopropyl ... Examples of the alkylsulfonylamino group include branched alkylsulfonylamino groups such as milsulfonylamino, t-amylsulfonylamino, isohexylsulfonylamino, t-hexylsulfonylamino, isoheptylsulfonylamino, t-heptylsulfonylamino, isooctylsulfonylamino, t-octylsulfonylamino, 2-ethylhexylsulfonylamino, isononylsulfonylamino, and isodecylsulfonylamino; and cyclic alkylsulfonylamino groups such as cyclopropylsulfonylamino, cyclobutylsulfonylamino, cyclopentylsulfonylamino, cyclohexylsulfonylamino, and cycloheptylsulfonylamino.

The arylsulfonylamino group in R ₁ to R ₅ of the formula (1) includes a C6 to C12 arylsulfonylamino group, such as phenylsulfonylamino, toluenesulfonylamino, naphthylsulfonylamino, and biphenylsulfonylamino.

The monoalkylamino group in R ₁ to R ₅ of formula (1) includes a C1 to C10 linear, branched or cyclic monoalkylamino group, such as a linear monoalkylamino group such as methylamino, ethylamino, n-propylamino, n-butylamino, n-pentylamino, n-hexylamino, n-heptylamino, n-octylamino, n-nonylamino or n-decylamino; a branched monoalkylamino group such as isopropylamino, isobutylamino, sec-butylamino, t-butylamino, isoamylamino, t-amylamino, isohexylamino, t-hexylamino, isoheptylamino, t-heptylamino, isooctylamino, t-octylamino, 2-ethylhexylamino, isononylamino or isodecylamino; and a cyclic monoalkylamino group such as cyclopropylamino, cyclobutylamino, cyclopentylamino, cyclohexylamino or cycloheptylamino.

Examples of the dialkylamino group in R ₁ to R ₅ of formula (1) include linear, branched or cyclic C1 to C10 dialkylamino groups, such as linear dialkylamino groups such as dimethylamino, diethylamino, di-n-propylamino, di-n-butylamino, di-n-pentylamino, di-n-hexylamino, di-n-heptylamino, di-n-octylamino, di-n-nonylamino and di-n-decylamino, diisopropylamino, diisobutylamino, di-sec-butylamino, di-t-butylamino and di-n-decylamino, di-n-propylamino, di-n-butyl ... Examples of the alkylamino group include branched dialkylamino groups such as isoamylamino, di-t-amylamino, diisohexylamino, di-t-hexylamino, diisoheptylamino, di-t-heptylamino, diisooctylamino, di-t-octylamino, di-(2-ethylhexyl)amino, diisononylamino, and diisodecylamino; and cyclic dialkylamino groups such as dicyclopropylamino, dicyclobutylamino, dicyclopentylamino, dicyclohexylamino, and dicycloheptylamino.

The arylamino group in R ₁ to R ₅ of formula (1) includes a C6 to C12 monoarylamino group or diarylamino group, such as phenylamino (anilino), naphthylamino, biphenylamino, diphenylamino, dinaphthylamino, and di(biphenyl)amino.

In formula (1), R ₁ to R ₅ are an alkyl group or a hydrogen atom, more preferably a straight-chain C1 to C12 alkyl group or a hydrogen atom, and even more preferably a straight-chain C1 to C8 alkyl group or a hydrogen atom.
In addition, preferably, R ₁ , R ₂ , R ₄ , and R ₅ in formula (1) are a hydrogen atom, and R ₃ is a hydrogen atom, a halogen atom, a nitro group, an amino group, an alkyl group, an alkoxy group, an aryloxy group, an alkylcarbonyloxy group, an arylcarbonyloxy group, an alkylcarbonylamino group, an arylcarbonylamino group, an alkylsulfonylamino group, an arylsulfonylamino group, a monoalkylamino group, a dialkylamino group, or an arylamino group, more preferably a fluorine atom, a chlorine atom, a bromine atom, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, or an aryloxy group having 6 to 12 carbon atoms, and even more preferably a fluorine atom, a chlorine atom, an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 2 to 8 carbon atoms, or an aryloxy group having 6 to 12 carbon atoms.

The substitution position of the partial skeleton bonded to one of the benzene rings of the diphenylurea structure in formula (1) can be the ortho, meta, or para position relative to the aminocarbonyl group on the benzene ring, with the ortho or meta position being preferred and the meta position being more preferred.

（式（２）中、Ｒ_３は水素原子、ハロゲン原子、ニトロ基、アミノ基、アルキル基、アルコキシ基、アリールオキシ基、アルキルカルボニルオキシ基、アリールカルボニルオキシ基、アルキルカルボニルアミノ基、アリールカルボニルアミノ基、アルキルスルホニルアミノ基、アリールスルホニルアミノ基、モノアルキルアミノ基、ジアルキルアミノ基、アリールアミノ基を表す。）
更に、式（２）において、Ｒ_３はフッ素原子、塩素原子、臭素原子、炭素数１乃至１２のアルキル基、炭素数１乃至１２のアルコキシ基、炭素数６乃至１２のアリールオキシ基のいずれかであることが好ましく、より好ましくは、フッ素原子、塩素原子、炭素数１乃至８のアルキル基、炭素数２乃至８のアルコキシ基、炭素数６乃至１２のアリールオキシ基である。 Of the compounds of formula (1), the compounds of formula (2) are preferably used.

(In formula (2), _R3 represents a hydrogen atom, a halogen atom, a nitro group, an amino group, an alkyl group, an alkoxy group, an aryloxy group, an alkylcarbonyloxy group, an arylcarbonyloxy group, an alkylcarbonylamino group, an arylcarbonylamino group, an alkylsulfonylamino group, an arylsulfonylamino group, a monoalkylamino group, a dialkylamino group, or an arylamino group.)
Furthermore, in formula (2), _R3 is preferably any one of a fluorine atom, a chlorine atom, a bromine atom, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, and an aryloxy group having 6 to 12 carbon atoms, and more preferably a fluorine atom, a chlorine atom, an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 2 to 8 carbon atoms, or an aryloxy group having 6 to 12 carbon atoms.

In addition to the component (b), the composition may further contain a known electron-accepting compound.
The electron-accepting compound may be a compound selected from a group of compounds having an active proton, a group of pseudo-acidic compounds (a group of compounds which are not acids but act as an acid in the reversible thermochromic composition to cause the component (A) to develop color), and a group of compounds having an electron vacancy.
Examples of compounds having an active proton include compounds having a phenolic hydroxyl group and derivatives thereof, carboxylic acids and derivatives thereof, acidic phosphate esters and derivatives thereof, azole compounds and derivatives thereof, 1,2,3-triazole and derivatives thereof, cyclic carbosulfimides, halohydrins having 2 to 5 carbon atoms, sulfonic acids and derivatives thereof, inorganic acids, etc. As the carboxylic acid and derivatives thereof, aromatic carboxylic acids and derivatives thereof, or aliphatic carboxylic acids and derivatives thereof having 2 to 5 carbon atoms are preferred.
Examples of the pseudo-acidic compounds include metal salts of compounds having a phenolic hydroxyl group, metal salts of carboxylic acids, metal salts of acidic phosphates, metal salts of sulfonic acids, aromatic carboxylic acid anhydrides, aliphatic carboxylic acid anhydrides, mixed anhydrides of aromatic carboxylic acids and sulfonic acids, cycloolefin dicarboxylic acid anhydrides, urea and its derivatives, thiourea and its derivatives, guanidine and its derivatives, halogenated alcohols, and the like.
Examples of compounds having electron vacancies include borates, borate esters, inorganic salts, and the like.
Compounds having a phenolic hydroxyl group include a wide range of compounds from monophenol compounds to polyphenol compounds, and further include bisphenol compounds, trisphenol compounds, phenol-aldehyde condensation resins, etc. Compounds having a phenolic hydroxyl group preferably have at least two benzene rings. Compounds having a phenolic hydroxyl group may have a substituent such as an alkyl group, an aryl group, an acyl group, an alkoxycarbonyl group, a carboxyl group and its ester or amide group, or a halogen atom.
Examples of metals contained in metal salts of compounds having a phenolic hydroxyl group include sodium, potassium, calcium, zinc, zirconium, aluminum, magnesium, nickel, cobalt, tin, copper, iron, vanadium, titanium, lead, and molybdenum.

Examples of known electron-accepting compounds are given below.
Examples of the compound having one phenolic hydroxyl group include
Phenol,
o-cresol,
m-cresol,
p-cresol,
4-ethylphenol,
4-n-propylphenol,
4-n-butylphenol,
2-tert-butylphenol,
3-tert-butylphenol,
4-tert-butylphenol,
4-n-pentylphenol,
4-tert-pentylphenol,
4-n-octylphenol,
4-tert-octylphenol,
4-n-nonylphenol,
4-n-dodecylphenol,
3-n-pentadecylphenol,
4-n-stearylphenol,
1-(4-hydroxyphenyl)decan-1-one,
4-chlorophenol,
4-bromophenol,
4-trifluoromethylphenol,
4-methylthiophenol,
4-nitrophenol,
2-phenylphenol,
4-phenylphenol,
2-benzylphenol,
2-benzyl-4-chlorophenol,
4-cumylphenol,
4-hydroxybenzophenone,
4-chloro-4'-hydroxybenzophenone,
4-fluoro-4'-hydroxybenzophenone,
4-cyclohexylphenol,
2-hydroxybenzyl alcohol,
3-hydroxybenzyl alcohol,
4-hydroxybenzyl alcohol,
4-(2-hydroxyethyl)phenol,
3-methoxyphenol,
4-ethoxyphenol,
4-n-propoxyphenol,
4-n-butoxyphenol,
4-n-heptyloxyphenol,
4-(2-methoxyethyl)phenol,
α-naphthol,
β-naphthol,
2,3-dimethylphenol,
2,4-dimethylphenol,
2,6-dimethylphenol,
2,6-di-tert-butylphenol,
2,4-dichlorophenol,
2,4-difluorophenol,
Thymol,
3-methyl-4-methylthiophenol,
2-tert-butyl-5-methylphenol,
2,6-bis(hydroxymethyl)-4-methylphenol,
2,3,5-trimethylphenol,
2,6-bis(hydroxymethyl)-4-tert-octylphenol,
6-hydroxy-1,3-benzoxathiol-2-one,
2,4-bis(phenylsulfonyl)phenol,
2,4-bis(phenylsulfonyl)-5-methylphenol,
2,4-bis(4-methylphenylsulfonyl)phenol,
2-phenylphenol, 4-phenylphenol,
2,6-diphenylphenol,
3-benzylbiphenyl-2-ol,
3,5-dibenzylbiphenyl-4-ol,
4-cyano-4'-hydroxybiphenyl,
1-hydroxybenzotriazole,
1-hydroxy-5-methylbenzotriazole,
1-hydroxy-5-chlorobenzotriazole,
1-hydroxy-5-methoxybenzotriazole,
1-hydroxy-4-benzoylaminobenzotriazole,
1-hydroxy-4,5,6,7-tetrachlorobenzotriazole,
1,4-hydroxybenzotriazole,
1-hydroxy-5-nitrobenzotriazole,
1-hydroxy-5-phenylbenzotriazole,
1-hydroxy-5-benzylbenzotriazole,
1-hydroxy-5-ethylbenzotriazole,
1-hydroxy-5-n-octylbenzotriazole,
1-hydroxy-5-n-butylbenzotriazole,
n-Butyl 4-hydroxybenzoate,
n-Octyl 4-hydroxybenzoate,
2-heptadecafluorooctylethane 4-hydroxybenzoate,
benzyl 4-hydroxybenzoate,
4-hydroxybenzoic acid benzyl ester,
4-hydroxybenzoic acid-o-methylbenzyl
4-hydroxybenzoic acid-m-methylbenzyl
p-methylbenzyl 4-hydroxybenzoate,
p-ethylbenzyl 4-hydroxybenzoate,
p-propylbenzyl 4-hydroxybenzoate,
p-tert-butylbenzyl 4-hydroxybenzoate,
phenylethyl 4-hydroxybenzoate,
4-hydroxybenzoic acid-o-methylphenylethyl ester,
4-hydroxybenzoic acid-m-methylphenylethyl,
p-methylphenylethyl 4-hydroxybenzoate,
p-Ethylphenylethyl 4-hydroxybenzoate,
p-propylphenylethyl 4-hydroxybenzoate,
An example thereof is p-tert-butylphenylethyl 4-hydroxybenzoate.

Examples of compounds having two phenolic hydroxyl groups include
Resorcinol,
2-methylresorcinol,
4-n-hexylresorcinol,
4-n-octylresorcinol,
4-tert-octylresorcinol,
4-benzoylresorcinol,
4-nitroresorcinol,
β-Methyl resorcylate,
β-benzyl resorcylate,
2-chloro-4-pentanoylresorcinol,
6-chloro-4-pentanoylresorcinol,
2-chloro-4-hexanoylresorcinol,
6-chloro-4-hexanoylresorcinol,
2-chloro-4-propanoylresorcinol,
6-chloro-4-propanoylresorcinol,
2,6-dichloro-4-propanoylresorcinol,
6-fluoro-4-propanoylresorcinol,
2-chloro-4-phenylacetylresorcinol,
6-chloro-4-phenylacetylresorcinol,
2-chloro-4-β-phenylpropanoylresorcinol,
6-chloro-4-β-phenylpropanoylresorcinol,
2-chloro-4-phenoxyacetylresorcinol,
6-chloro-4-phenoxyacetylresorcinol,
4-benzoyl-2-chlororesorcinol,
6-chloro-4-m-methylbenzoylresorcinol,
4-[1',3',4',9'a-tetrahydro-6'-hydroxyspiro(cyclohexane-1,9'-[9H]-xanthene)-4'a-[2H]-yl]-1,3-benzenediol,
Hydroquinone,
Methylhydroquinone,
Trimethylhydroquinone,
Catechol,
4-tert-butylcatechol,
1,6-dihydroxynaphthalene,
2,7-dihydroxynaphthalene,
1,5-dihydroxynaphthalene,
2,6-dihydroxynaphthalene,
2,4-dihydroxybenzophenone,
4,4'-dihydroxybenzophenone,
2,4-dihydroxy-2'-methylbenzophenone,
2,4-dihydroxy-3'-methylbenzophenone,
2,4-dihydroxy-4'-methylbenzophenone,
2,4-dihydroxy-4'-ethylbenzophenone,
2,4-dihydroxy-4'-n-propylbenzophenone,
2,4-dihydroxy-4'-isopropylbenzophenone,
2,4-dihydroxy-4'-n-butylbenzophenone,
2,4-dihydroxy-4'-isobutylbenzophenone,
2,4-dihydroxy-4'-tert-butylbenzophenone,
2,4-dihydroxy-4'-n-pentylbenzophenone,
2,4-dihydroxy-4'-n-hexylbenzophenone,
2,4-dihydroxy-4'-n-heptylbenzophenone,
2,4-dihydroxy-4'-n-octylbenzophenone,
2,4-dihydroxy-4'-n-decylbenzophenone,
2,4-dihydroxy-2',3'-dimethylbenzophenone,
2,4-dihydroxy-2',4'-dimethylbenzophenone,
2,4-dihydroxy-2',5'-dimethylbenzophenone,
2,4-dihydroxy-2',6'-dimethylbenzophenone,
2,4-dihydroxy-3',4'-dimethylbenzophenone,
2,4-dihydroxy-3',5'-dimethylbenzophenone,
2,4-dihydroxy-2',4',6'-trimethylbenzophenone,
2,4-dihydroxy-2'-methoxybenzophenone,
2,4-dihydroxy-3'-methoxybenzophenone,
2,4-dihydroxy-4'-methoxybenzophenone,
2,4-dihydroxy-2'-ethoxybenzophenone,
2,4-dihydroxy-4'-ethoxybenzophenone,
2,4-dihydroxy-4'-n-propoxybenzophenone,
2,4-dihydroxy-4'-isopropoxybenzophenone,
2,4-dihydroxy-4'-n-butoxybenzophenone,
2,4-dihydroxy-4'-isobutoxybenzophenone,
2,4-dihydroxy-4'-n-pentyloxybenzophenone,
2,4-dihydroxy-4'-n-hexyloxybenzophenone,
2,4-dihydroxy-4'-n-heptyloxybenzophenone,
2,4-dihydroxy-4'-n-octyloxybenzophenone,
2,4-dihydroxy-4'-n-nonyloxybenzophenone,
2,4-dihydroxy-2',3'-dimethoxybenzophenone,
2,4-dihydroxy-2',4'-dimethoxybenzophenone,
2,4-dihydroxy-2',5'-dimethoxybenzophenone,
2,4-dihydroxy-2',6'-dimethoxybenzophenone,
2,4-dihydroxy-3',4'-dimethoxybenzophenone,
2,4-dihydroxy-3',5'-dimethoxybenzophenone,
2,4-dihydroxy-3',4'-diethoxybenzophenone,
2,4-dihydroxy-2',3',4'-trimethoxybenzophenone,
2,4-dihydroxy-2',3',6'-trimethoxybenzophenone,
2,4-dihydroxy-3',4',5'-trimethoxybenzophenone,
Examples include 2,4-dihydroxy-3',4',5'-triethoxybenzophenone.

Further, examples of the bisphenol compound include
1,1-bis(4-hydroxyphenyl)ethane,
1,1-bis(4-hydroxyphenyl)propane,
1,1-bis(4-hydroxyphenyl)n-butane,
1,1-bis(4-hydroxyphenyl) n-pentane,
1,1-bis(4-hydroxyphenyl)n-hexane,
1,1-bis(4-hydroxyphenyl) n-heptane,
1,1-bis(4-hydroxyphenyl) n-octane,
1,1-bis(4-hydroxyphenyl)-n-nonane,
1,1-bis(4-hydroxyphenyl) n-decane,
1,1-bis(4-hydroxy-3-methylphenyl)decane,
1,1-bis(4-hydroxyphenyl)-n-dodecane,
1,1-bis(4-hydroxyphenyl)-2-methylpropane,
1,1-bis(4-hydroxyphenyl)-3-methylbutane,
1,1-bis(4-hydroxyphenyl)-3-methylpentane,
1,1-bis(4-hydroxyphenyl)-2,3-dimethylpentane,
1,1-bis(4-hydroxyphenyl)-2-ethylbutane,
1,1-bis(4-hydroxyphenyl)-2-ethylhexane,
1,1-bis(4-hydroxyphenyl)-3,7-dimethyloctane,
1,1-bis(4-hydroxyphenyl)cyclohexane,
1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane,
1,1-bis(4-hydroxy-3-methyl)cyclohexane,
Diphenolic acid,
1-phenyl-1,1-bis(4-hydroxyphenyl)methane,
2,2-bis(4-hydroxyphenyl)propane,
2,2-bis(4-hydroxyphenyl)n-butane,
2,2-bis(4-hydroxyphenyl)n-pentane,
2,2-bis(4-hydroxyphenyl)n-hexane,
2,2-bis(4-hydroxyphenyl) n-heptane,
2,2-bis(4-hydroxyphenyl) n-octane,
2,2-bis(4-hydroxyphenyl)n-nonane,
2,2-bis(4-hydroxyphenyl)n-decane,
2,2-bis(4-hydroxyphenyl)-n-dodecane,
2,2-bis(4-hydroxyphenyl)-6,10,14-trimethylpentadecane,
1-phenyl-1,1-bis(4-hydroxyphenyl)ethane,
2,2-bis(4-hydroxyphenyl)methylpropionate,
2,2-bis(4-hydroxyphenyl)butyl propionate,
2,2-bis(4-hydroxy-3-methylphenyl)methyl propionate,
2,2-bis(4-hydroxyphenyl)ethyl propionate,
2,2-bis(4-hydroxyphenyl)-4-methylpentane,
2,2-bis(4-hydroxyphenyl)-4-methylhexane,
2,2-bis(4-hydroxyphenyl)hexafluoropropane,
2,2-bis(3,5-dihydroxymethyl-4-hydroxyphenyl)hexafluoropropane,
2,2-bis(4-hydroxy-3-methylphenyl)propane,
2,2-bis(4-hydroxy-3-methylphenyl)butane,
2,2-bis(4-hydroxy-3-isopropylphenyl)propane,
2,2-bis(3-sec-butylphenyl-4-hydroxy)propane,
2,2-bis(4-hydroxy-3-phenylphenyl)propane,
2,2-bis(3-tert-butyl-4-hydroxyphenyl)propane,
2,2-bis(3-fluoro-4-hydroxyphenyl)propane,
2,2-bis(3,5-dihydroxymethyl-4-hydroxyphenyl)propane,
9,9-bis(4-hydroxy-3-methylphenyl)fluorene,
1,3-bis[2-(4-hydroxyphenyl)-2-propyl]benzene,
1,4-bis[2-(4-hydroxyphenyl)-2-propyl]benzene,
3,3-bis(4-hydroxyphenyl)oxindole,
3,3-bis(4-hydroxy-3-methylphenyl)oxindole,
bis(2-hydroxyphenyl)methane,
Bis(2-hydroxy-5-methylphenyl)methane,
Bis(2-hydroxy-3-hydroxymethyl-5-methyl)methane,
4,4'-[1,4-phenylenebis(1-methylethylidene)]bis(2-methylphenol),
1,1-bis(4-hydroxy-3-phenylphenyl)cyclohexane,
3,3-ethyleneoxydiphenol,
1,4-bis(4-hydroxybenzoate)-3-methylbenzene,
4,4″-dihydroxy-3″-methyl-p-terphenyl,
4,4″-dihydroxy-3″-isopropyl-p-terphenyl,
2,2-dimethyl-1,3-bis(4-hydroxybenzoyloxy)propane,
2,2'-biphenol,
4,4'"-dihydroxy-p-quaterphenyl,
4,4-dihydroxydiphenyl ether,
bis(4-hydroxyphenylthioethyl)ether bis(4-hydroxyphenyl)sulfone,
4-benzyloxy-4'-hydroxydiphenyl sulfone,
4-(4-methylbenzyloxy)-4'-hydroxydiphenyl sulfone,
4-(4-ethylbenzyloxy)-4'-hydroxydiphenyl sulfone,
4-(4-n-propylbenzyloxy)-4'-hydroxydiphenyl sulfone,
4-(4-isopropylbenzyloxy)-4'-hydroxydiphenyl sulfone,
4-(4-n-butylbenzyloxy)-4'-hydroxydiphenyl sulfone,
4-(4-isobutylbenzyloxy)-4'-hydroxydiphenyl sulfone,
4-(4-sec-butylbenzyloxy)-4'-hydroxydiphenyl sulfone,
4-(4-tert-butylbenzyloxy)-4'-hydroxydiphenyl sulfone,
4-(3-methylbenzyloxy)-4'-hydroxydiphenyl sulfone,
4-(3-ethylbenzyloxy)-4'-hydroxydiphenyl sulfone,
4-(3-n-propylbenzyloxy)-4'-hydroxydiphenyl sulfone,
4-(3-isopropylbenzyloxy)-4'-dihydroxyphenyl sulfone,
4-(3-n-butylbenzyloxy)-4'-hydroxydiphenyl sulfone,
4-(3-isobutylbenzyloxy)-4'-hydroxydiphenyl sulfone,
4-(3-sec-butylbenzyloxy)-4'-hydroxydiphenyl sulfone,
4-(3-tert-butylbenzyloxy)-4'-hydroxydiphenyl sulfone,
4-(2-methylbenzyloxy)-4'-hydroxydiphenyl sulfone,
4-(2-ethylbenzyloxy)-4'-hydroxydiphenyl sulfone,
4-(2-n-propylbenzyloxy)-4'-hydroxydiphenyl sulfone,
4-(2-isopropylbenzyloxy)-4'-hydroxydiphenyl sulfone,
4-(2-n-butylbenzyloxy)-4'-hydroxydiphenyl sulfone,
4-(2-isobutylbenzyloxy)-4'-hydroxydiphenyl sulfone,
4-(2-sec-butylbenzyloxy)-4'-hydroxydiphenyl sulfone,
4-(2-tert-butylbenzyloxy)-4'-hydroxydiphenyl sulfone,
2,4'-dihydroxydiphenyl sulfone,
3,4'-dihydroxydiphenyl sulfone,
4-hydroxydiphenyl sulfone,
4-methyl-4'-hydroxyphenyl sulfone,
4-ethyl-4'-hydroxydiphenyl sulfone,
4-n-propyl-4'-hydroxydiphenyl sulfone,
4-isopropyl-4'-hydroxydiphenyl sulfone,
4-chloro-4'-hydroxydiphenyl sulfone,
4-fluoro-4'-hydroxydiphenyl sulfone,
4-chloro-2-methyl-4'-hydroxydiphenyl sulfone,
4-methoxy-4'-hydroxydiphenyl sulfone,
4-ethoxy-4'-hydroxydiphenyl sulfone,
4-n-propoxy-4'-hydroxydiphenyl sulfone,
4-isopropoxy-4'-hydroxydiphenyl sulfone,
4-n-butoxy-4'-hydroxydiphenyl sulfone,
4-isobutoxy-4'-hydroxydiphenyl sulfone,
4-sec-butoxy-4'-hydroxydiphenyl sulfone,
4-tert-butoxy-4'-hydroxydiphenyl sulfone,
4-n-pentyloxy-4'-hydroxydiphenyl sulfone,
4-isopentyloxy-4'-hydroxydiphenyl sulfone,
4-(1-propenyloxy)-4'-hydroxydiphenyl sulfone,
4-(2-propenyloxy)-4'-hydroxydiphenyl sulfone,
4-benzyloxy-4'-hydroxydiphenyl sulfone,
4-(β-phenoxyethoxy)-4'-hydroxydiphenyl sulfone,
4-(β-phenoxypropoxyl)-4'-hydroxydiphenyl sulfone,
bis(2-allyl-4-hydroxydiphenyl)sulfone,
bis[4-hydroxy-3-(2-propenyl)phenyl]sulfone,
bis(3,5-dibromo-4-hydroxyphenyl)sulfone,
bis(3,5-dichloro-4-hydroxyphenyl)sulfone,
bis(3-phenyl-4-hydroxyphenyl)sulfone,
bis(4-hydroxy-3-n-propylphenyl)sulfone,
bis(4-hydroxy-3-methylphenyl)sulfone,
3,4-dihydroxydiphenyl sulfone,
3',4'-dihydroxy-4-methyldiphenyl sulfone,
3,4,4'-trihydroxydiphenyl sulfone,
bis(3,4-dihydroxyphenyl)sulfone,
2,3,4-trihydroxydiphenyl sulfone,
4-isopropoxy-4'-hydroxydiphenyl sulfone,
4-n-propoxy-4'-hydroxydiphenyl sulfone,
4-allyloxy-4'-hydroxydiphenyl sulfone,
4-benzyloxy-4'-hydroxydiphenyl sulfone,
4-(2-propenyloxy)-4'-hydroxydiphenyl sulfone,
3-benzyl-4-benzyloxy-4'-hydroxydiphenyl sulfone,
3-phenethyl-4-phenethyloxy-4'-hydroxydiphenyl sulfone,
3-methylbenzyl-4-methylbenzyloxy-4'-hydroxydiphenyl sulfone,
4-benzyloxy-3'-benzyl-4'-hydroxydiphenyl sulfone,
4-phenethyloxy-3'-phenethyl-4'-hydroxydiphenyl sulfone,
4-methylbenzyloxy-3'-methylbenzyl-4'-hydroxydiphenyl sulfone,
α,α'-bis{4-(p-hydroxyphenylsulfone)phenoxy}-p-xylene,
4,4'-{oxybis(ethylene oxide-p-phenylene sulfonyl)}diphenol,
Bis(4-hydroxyphenyl)sulfide, bis(4-hydroxy-3-methylphenyl)sulfide,
Bis(3,5-dimethyl-4-hydroxyphenyl)sulfide,
bis(3-ethyl-4-hydroxyphenyl)sulfide,
Bis(3,5-diethyl-4-hydroxyphenyl)sulfide,
Bis(4-hydroxy-3-n-propylphenyl)sulfide,
Bis(3,5-di-n-propyl-4-hydroxyphenyl)sulfide,
Bis(3-tert-butyl-4-hydroxyphenyl)sulfide,
Bis(3,5-di-tert-butyl-4-hydroxyphenyl)sulfide,
Bis(4-hydroxy-3-n-pentylphenyl)sulfide,
Bis(3-n-hexyl-4-hydroxyphenyl)sulfide,
Bis(3-n-heptyl-4-hydroxyphenyl)sulfide,
Bis(5-tert-octyl-2-hydroxyphenyl)sulfide,
Bis(2-hydroxy-3-tert-octylphenyl)sulfide,
Bis(2-hydroxy-5-n-octyl-phenyl)sulfide,
bis(5-chloro-2-hydroxyphenyl)sulfide,
Bis(3-cyclohexyl-4-hydroxyphenyl)sulfide,
bis(4-hydroxyphenylthioethoxy)methane,
1,5-(4-hydroxyphenylthio)-3-oxypentane,
Examples include 1,8-bis(4-hydroxyphenylthio)-3,6-dioxaoctane.

Examples of compounds having three phenolic hydroxyl groups include pyrogallol, phloroglucinol, phloroglucinol carboxylic acid, gallic acid, octyl gallate, and dodecyl gallate.

Further examples of trisphenol compounds include:
4,4',4"-Methylidynetrisphenol,
4,4',4"-Methylidynetris(2-methylphenol),
4,4'-[(2-hydroxyphenyl)methylene]bis(2,3,5-trimethylphenol),
4,4'-[(4-hydroxyphenyl)methylene]bis(2-methylphenol),
4,4'-[(4-hydroxyphenyl)methylene]bis(2,6-dimethylphenol),
4,4'-[(4-hydroxy-3-methoxyphenyl)methylene]bisphenol,
4,4'-[(4-hydroxyphenyl)methylene]bis(2-cyclohexyl-5-methylphenol),
4,4',4"-ethylidynetrisphenol,
4,4',4"-ethylidynetris(2-methylphenol),
4,4'-[(2-hydroxyphenyl)methylene]bis(2-cyclohexyl-5-methylphenol),
2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-methylphenol,
2,4-bis[(2-hydroxy-5-methylphenyl)methyl]-6-cyclohexylphenol,
4,4'-[1-{4-[1-(4-hydroxyphenyl)-1-methylethyl]phenyl}methylidene]bisphenol,
4,4'-[1-{4-[1-(4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bisphenol,
4,4'-[1-{4-[1-(4-hydroxyphenyl)-1-methylethyl]phenyl}propylidene]bisphenol,
4,4'-[1-{4-[1-(4-hydroxyphenyl)-1-methylethyl]phenyl}butylidene]bisphenol,
4,4'-[1-{4-[1-(4-hydroxyphenyl)-1-methylethyl]phenyl}pentylidene]bisphenol,
4,4'-[1-{4-[1-(4-hydroxyphenyl)-1-methylethyl]phenyl}hexylidene]bisphenol,
4,4'-[1-{4-[1-(4-hydroxyphenyl)-1-methylethyl]phenyl}heptylidene]bisphenol,
4,4'-[1-{4-[1-(4-hydroxyphenyl)-1-methylethyl]phenyl}isobutylidene]bisphenol,
4,4'-[1-{4-[1-(4-hydroxyphenyl)-1-methylethyl]phenyl}neopentylidene]bisphenol,
2,2'-[1-{4-[1-(2-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bisphenol,
3,3'-[1-{4-[1-(3-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bisphenol,
4,4'-[1-{4-[1-(3-fluoro-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis(2-fluorophenol),
4,4'-[1-{4-[1-(3-chloro-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis(2-chlorophenol),
4,4'-[1-{4-[1-(3-bromo-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis(2-bromophenol),
4,4'-[1-{4-[1-(4-hydroxy-3-methylphenyl)-1-methylethyl]phenyl}ethylidene]bis(2-methylphenol),
4,4'-[1-{4-[1-(3-ethyl-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis(2-ethylphenol),
4,4'-[1-{4-[1-(3-tert-butyl-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis(2-tert-butylphenol),
4,4'-[1-{4-[1-(4-hydroxy-3-trifluoromethylphenyl)-1-methylethyl]phenyl}ethylidene]bis(2-trifluoromethylphenol),
1,1-bis(4-hydroxyphenyl)-4-(4-hydroxy-α-ethyl)benzylcyclohexane,
4,4'-[(3-ethoxy-4-hydroxyphenyl)methylene]bisphenol,
4,4'-[(3-hydroxyphenyl)methylene]bis(2,6-dimethylphenol),
2,2'-[(4-hydroxyphenyl)methylene]bis(3,5-dimethylphenol),
4,4'-[(4-hydroxy-3-methoxyphenyl)methylene]bis(2,6-dimethylphenol),
2,2'-[(2-hydroxyphenyl)methylene]bis(3,5,6-trimethylphenol),
4,4'-[(3-hydroxyphenyl)methylene]bis(2,3,6-trimethylphenol),
4,4'-[(4-hydroxyphenyl)methylene]bis(2,3,6-trimethylphenol),
4,4'-[(3-hydroxyphenyl)methylene]bis(2-cyclohexyl-5-methylphenol),
4,4'-[(4-hydroxyphenyl-3-methoxy)methylene]bis(2-cyclohexyl-5-methylphenol),
1,1-bis(4-hydroxyphenyl)-4-hydroxyphenylcyclohexane,
4,4'-[3-(5-cyclohexyl-4-hydroxy-2-methylphenyl)-3-phenyl)propylidene]bis(2-cyclohexyl-5-methylphenol),
4,4'-[(2-hydroxyphenyl)methylene]bis(2-methylphenol),
2,4',4"-Methylidynetrisphenol,
4,4'-[(2-hydroxyphenyl)methylene]bis(3-methylphenol),
4,4'-[4-(4-hydroxyphenyl)-sec-butylidene]bis(4-hydroxyphenol),
2,2'-[(3-hydroxyphenyl)methylene]bis(3,5-dimethylphenol),
4,4'-[(2-hydroxy-3-methoxyphenyl)methylene]bis(2,5-dimethylphenol),
4,4'-[(2-hydroxy-3-methoxyphenyl)methylene]bis(2,6-dimethylphenol),
2,2'-[(2-hydroxy-3-methoxyphenyl)methylene]bis(3,5-dimethylphenol),
2,2'-[(3-hydroxy-4-methoxyphenyl)methylene]bis(3,5-dimethylphenol),
2,2'-[(4-hydroxy-3-methoxyphenyl)methylene]bis(3,5-dimethylphenol),
4,4'-[(2-hydroxyphenyl)methylene]bis(2-isopropylphenol),
4,4'-[(3-hydroxyphenyl)methylene]bis(2-isopropylphenol),
4,4'-[(4-hydroxyphenyl)methylene]bis(2-isopropylphenol),
2,2'-[(3-hydroxyphenyl)methylene]bis(3,5,6-trimethylphenol),
2,2'-[(4-hydroxyphenyl)methylene]bis(3,5,6-trimethylphenol),
2,2'-[(4-3-ethoxy-4-hydroxyphenyl)methylene]bis(3,5-dimethylphenol),
1,1-bis(4-hydroxy-3-methylphenyl)-4-(4-hydroxyphenyl)cyclohexane,
4,4'-[(2-hydroxy-3-methoxyphenyl)methylene]bis(2-isopropylphenol),
4,4'-[(3-hydroxy-4-methoxyphenyl)methylene]bis(2-isopropylphenol),
4,4'-[(4-hydroxy-3-methoxyphenyl)methylene]bis(2-isopropylphenol),
2,2'-[(2-hydroxy-3-methoxyphenyl)methylene]bis(3,5,6-trimethylphenol),
2,2'-[(3-hydroxy-4-methoxyphenyl)methylene]bis(3,5,6-trimethylphenol),
2,2'-[(4-hydroxy-3-methoxyphenyl)methylene]bis(3,5,6-trimethylphenol),
4,4'-[(3-ethoxy-4-hydroxyphenyl)methylene]bis(2-isopropylphenol),
2,2'-[(3-ethoxy-4-hydroxyphenyl)methylene]bis(3,5,6-trimethylphenol),
4,4'-[(3-ethoxy-4-hydroxyphenyl)methylene]bis(2,3,6-trimethylphenol),
1,1-bis(3,5-dimethyl-4-hydroxyphenyl)-4-(4-hydroxyphenyl)cyclohexane,
4,4'-[(4-hydroxy-3-methoxyphenyl)methylene]bis(2-tert-butyl-5-methylphenol),
4,4'-[(2-hydroxyphenyl)methylene]bis(2-cyclohexylphenol),
4,4'-[(3-hydroxyphenyl)methylene]bis(2-cyclohexylphenol),
4,4'-[(3-ethoxy-4-hydroxyphenyl)methylene]bis(2-tert-butyl-6-methylphenol),
4,4'-[(3-methoxy-2-hydroxyphenyl)methylene]bis(2-cyclohexylphenol),
4,4'-[(3-hydroxy-4-methoxyphenyl)methylene]bis(2-cyclohexylphenol),
4,4'-[1-{4-[1-(3-fluoro-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis(2-tert-butylphenol),
4,4'-[1-{4-[1-(3,5-dimethyl-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis(2,6-dimethylphenol),
4,4'-[(3-ethoxy-4-hydroxyphenyl)methylene]bis(2-cyclohexyl-5-methylphenol),
4,4'-[(3-cyclohexyl-4-hydroxyphenyl)ethylidene]bis(2-cyclohexylphenol),
4,4'-[(5-cyclohexyl-4-hydroxy-2-methoxyphenyl)ethylidene]bis(2-cyclohexyl-5-methylphenol),
4,4'-[1-{4-[1-(3-cyclohexyl-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis(2-cyclohexylphenol),
4,4'-[1-{4-[1-(3-fluoro-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bisphenol,
4,4'-[1-{4-[1-(3-fluoro-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis(2-methylphenol),
4,4'-[1-{4-[1-(3-fluoro-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis(2,6-dimethylphenol),
2,6-bis[(5-fluoro-2-hydroxyphenyl)methyl]-4-methylphenol,
2,6-bis[(3,5-dimethyl-4-hydroxyphenyl)methyl]-4-methylphenol,
2,6-bis[(4-hydroxyphenyl)methyl]-4-methylphenol, 2,6-bis[(4-hydroxyphenyl)methyl]-4-ethylphenol,
2,4-bis[(4-hydroxy-3-methylphenyl)methyl]-6-methylphenol,
2,6-bis[(4-hydroxy-3-methylphenyl)methyl]-4-methylphenol,
2,6-bis[(4-hydroxy-3-methylphenyl)methyl]-4-ethylphenol,
2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-ethylphenol,
2,6-bis[(3,5-dimethyl-2-hydroxyphenyl)methyl]-4-methylphenol,
2,6-bis[(2,4-dimethyl-6-hydroxyphenyl)methyl]-4-methylphenol,
2,4-bis[(4-hydroxyphenyl)methyl]-6-cyclohexylphenol,
2,6-bis[(2,5-dimethyl-4-hydroxyphenyl)methyl]-3,4-dimethylphenol,
2,6-bis[(2,5-dimethyl-4-hydroxyphenyl)methyl]-4-ethylphenol,
2,6-bis[(4-hydroxy-2,3,6-trimethylphenyl)methyl]-4-methylphenol,
2,4-bis[(4-hydroxy-3-methylphenyl)methyl]-6-cyclohexylphenol,
2,6-bis[(4-hydroxy-3-methylphenyl)methyl]-4-cyclohexylphenol,
2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-cyclohexylphenol,
2,6-bis[(4-hydroxy-2,3,5-trimethylphenyl)methyl]-4-ethylphenol,
2,4-bis[(2,5-dimethyl-4-hydroxyphenyl)methyl]-6-cyclohexylphenol,
4,4',4"-Methylidynetris(2,6-dimethylphenol),
α-(4-hydroxy-3-methylphenyl)-α,α'-bis(4-hydroxyphenyl)-1-ethyl-4-isopropylbenzene,
α'-(4-hydroxy-3-methylphenyl)-α,α-bis(4-hydroxyphenyl)-1-ethyl-4-isopropylbenzene,
α,α-bis(4-hydroxy-3-methylphenyl)-α'-(4-hydroxyphenyl)-1-ethyl-4-isopropylbenzene,
α,α'-bis(4-hydroxy-3-methylphenyl)-α-(4-hydroxyphenyl)-1-ethyl-4-isopropylbenzene,
1,1-bis(4-hydroxyphenyl)-4-[1-(4-hydroxyphenyl)-1-methylpropyl]cyclohexane,
2,6-bis[(3,5-dimethyl-4-hydroxyphenyl)methyl]-4-ethylphenol,
1,1'-bis(4-hydroxyphenyl)-4-[1-(4-hydroxyphenyl)propyl]cyclohexane,
1,1'-bis(4-hydroxy-3-methylphenyl)-4-[1-(4-hydroxyphenyl)propyl]cyclohexane,
1,1'-bis(3,5-dimethyl-4-hydroxyphenyl)-4-[1-(4-hydroxyphenyl)propyl]cyclohexane,
1-(4-hydroxyphenyl)-1-[4,4-bis(4-hydroxyphenyl)cyclohexyl]-4-isopropylcyclohexane,
4,4'-[3-(2,5-dimethyl-4-hydroxyphenyl)butylene]bis(2,5-dimethylphenol),
1,3,5-tri(4-hydroxy-3-phenylphenyl)adamantane,
1,3,5-tri(3-cyclohexyl-4-hydroxyphenyl)adamantane,
2,4-bis[(3,5-dimethyl-4-hydroxyphenyl)methyl]-6-cyclohexylphenol,
2,6-bis[(2,5-dimethyl-4-hydroxyphenyl)methyl]-4-cyclohexylphenol,
2,4-bis[(3-cyclohexyl-4-hydroxyphenyl)methyl]-6-methylphenol,
2,4-bis[(4-hydroxy-2,3,5-trimethylphenyl)methyl]-6-cyclohexylphenol,
2,6-bis[(5-fluoro-2-hydroxyphenyl)methyl]-4-fluorophenol,
2,6-bis[(3-fluoro-4-hydroxyphenyl)methyl]-4-fluorophenol,
2,4-bis[(3-fluoro-4-hydroxyphenyl)methyl]-6-methylphenol,
4,4'-[3-(5-cyclohexyl-4-hydroxy-2-methylphenyl)-3-biphenylpropylidene]bis(5-cyclohexyl-2-methylphenol),
4,4'-[3-(2,5-dimethyl-4-hydroxyphenyl)-3-phenylpropylidene]bis(2,5-dimethylphenol),
2,4-bis[(2,5-dimethyl-4-hydroxyphenyl)methyl]-6-methylphenol, 1,1,2-tris(4-hydroxyphenyl)ethane,
1,1,3-tris(4-hydroxyphenyl)propane, 1,1,4-tris(4-hydroxyphenyl)butane,
1,2,2-tris(4-hydroxyphenyl)propane, 1,2,2-tris(4-hydroxyphenyl)butane,
1,2,2-tris(4-hydroxyphenyl)pentane, 1,2,2-tris(4-hydroxyphenyl)hexane,
1,2,2-tris(4-hydroxyphenyl)heptane, 1,2,2-tris(4-hydroxyphenyl)octane,
1,2,2-tris(4-hydroxyphenyl)-3-methylbutane 1,2,2-tris(4-hydroxyphenyl)-3,3-dimethylbutane,
1,2,2-tris(4-hydroxyphenyl)-4,4-dimethylpentane, 1,3,3-tris(4-hydroxyphenyl)butane,
1,3,3-tris(4-hydroxyphenyl)pentane, 1,3,3-tris(4-hydroxyphenyl)hexane,
1,3,3-tris(4-hydroxyphenyl)heptane, 1,3,3-tris(4-hydroxyphenyl)octane,
1,3,3-tris(4-hydroxyphenyl)nonane, 1,4,4-tris(4-hydroxyphenyl)pentane,
1,4,4-tris(4-hydroxyphenyl)hexane, 1,4,4-tris(4-hydroxyphenyl)heptane,
1,4,4-tris(4-hydroxyphenyl)octane, 1,4,4-tris(4-hydroxyphenyl)nonane,
1,4,4-tris(4-hydroxyphenyl)decane, 1,2,2-tris(2-hydroxyphenyl)propane,
1,1,2-tris(3-hydroxyphenyl)propane,
1-(4-hydroxyphenyl)-2,2-bis(2-hydroxyphenyl)propane,
1,2,2-tris(3-fluoro-4-hydroxyphenyl)propane,
1,2,2-tris(3-chloro-4-hydroxyphenyl)propane,
1,2,2-tris(3-bromo-4-hydroxyphenyl)propane,
2,2-bis(3-ethyl-4-hydroxyphenyl)-1-(4-hydroxyphenyl)propane,
2,2-bis(3-tert-butyl-4-hydroxyphenyl)-1-(4-hydroxyphenyl)propane,
2,2-bis(2-hydroxy-3-biphenylyl)-1-(4-hydroxyphenyl)propane,
2,2-bis(3-trifluoromethyl-4-hydroxyphenyl)-1-(4-hydroxyphenyl)propane,
2-(3-methyl-4-hydroxyphenyl)-1,2-bis(4-hydroxyphenyl)propane,
1-(3-methyl-4-hydroxyphenyl)-2,2-bis(4-hydroxyphenyl)propane,
3-(3-methyl-4-hydroxyphenyl)-1,3-bis(4-hydroxyphenyl)butane,
1-(3-methyl-4-hydroxyphenyl)-3,3-bis(4-hydroxyphenyl)butane,
4-(3-methyl-4-hydroxyphenyl)-1,4-bis(4-hydroxyphenyl)pentane,
1-(3-methyl-4-hydroxyphenyl)-4,4-bis(4-hydroxyphenyl)pentane,
1,2-bis(3-methyl-4-hydroxyphenyl)-2-(4-hydroxyphenyl)propane,
3,3-bis(3-methyl-4-hydroxyphenyl)-1-(4-hydroxyphenyl)butane,
1,3-bis(3-methyl-4-hydroxyphenyl)-3-(4-hydroxyphenyl)butane,
4,4-bis(3-methyl-4-hydroxyphenyl)-1-(4-hydroxyphenyl)pentane,
1,4-bis(3-methyl-4-hydroxyphenyl)-4-(4-hydroxyphenyl)pentane,
1,1,2-tris(3-methyl-4-hydroxyphenyl)ethane,
1,2,2-tris(3-methyl-4-hydroxyphenyl)propane,
1,1,3-tris(3-methyl-4-hydroxyphenyl)propane,
1,3,3-tris(3-methyl-4-hydroxyphenyl)butane,
1,1,4-tris(3-methyl-4-hydroxyphenyl)butane,
1,4,4-tris(3-methyl-4-hydroxyphenyl)pentane,
4,4'-[4-(4-hydroxyphenyl)-sec-butylidene]bis(2-methylphenol)
Examples include:

Examples of compounds having four or more phenolic hydroxyl groups include
Bis[2-hydroxy-3-(2-hydroxy-5-methylbenzyl)-5-methylphenyl]methane,
4,6-bis[(4-hydroxyphenyl)methyl]-1,3-benzenediol,
4,4'-[(3,4-dihydroxyphenyl)methylene]bis(2,6-dimethylphenol),
4,4'-[(3,4-dihydroxyphenyl)methylene]bis(2-cyclohexyl-5-methylphenol),
4,4'-[(3,4-dihydroxyphenyl)methylene]bis(2-methylphenol),
4,4'-[(3,4-dihydroxyphenyl)methylene]bis(2,3,6-trimethylphenol),
1,1,2,2-tetrakis(4-hydroxyphenyl)ethane,
1,1,2,2-tetrakis(4-hydroxy-3-methylphenyl)ethane,
1,1,2,2-tetrakis(3,5-dimethyl-4-hydroxyphenyl)ethane,
α,α',4α",α'"-tetrakis(3,5-dimethyl-4-hydroxyphenyl)-1,4-dimethylbenzene,
2,2'-bis[4,4-bis(4-hydroxy-3-methylphenyl)cyclohexyl]propane,
2,2'-[(3,4-dihydroxyphenyl)methylene]bis(3,5-dimethylphenol),
3,6-bis[(3,5-dimethyl-4-hydroxyphenyl)methyl]catechol,
4,6-bis[(3,5-dimethyl-4-hydroxyphenyl)methyl]-1,3-benzenediol,
2,2'-[(3,4-dihydroxyphenyl)methylene]bis(3,5,6-trimethylphenol),
4,4'-[(3,4-dihydroxyphenyl)methylene]bis(2-cyclohexylphenol),
bis[3-(2-hydroxybenzyl)-4-hydroxy-5-methylphenyl]methane,
bis[3-(3-hydroxybenzyl)-4-hydroxy-5-methylphenyl]methane,
bis[3-(4-hydroxybenzyl)-4-hydroxy-5-methylphenyl]methane,
Bis[3-(2-hydroxybenzyl)-2-hydroxy-5-methylphenyl]methane,
bis[3-(2-hydroxybenzyl)-3-hydroxy-5-methylphenyl]methane,
bis[3-(2-hydroxybenzyl)-4-hydroxy-5-methylphenyl]methane,
Bis[3-(3-hydroxy-2-methylbenzyl)-2-hydroxy-5-methylphenyl]methane,
Bis[3-(4-hydroxy-3-methylbenzyl)-2-hydroxy-5-methylphenyl]methane,
Bis[3-(3-hydroxy-4-methylbenzyl)-2-hydroxy-5-methylphenyl]methane,
Bis[3-(2-hydroxy-3-methylbenzyl)-2-hydroxy-5-methylphenyl]methane,
α,α',α",α'"-tetrakis(4-hydroxyphenyl)-1,4-dimethylbenzene,
Bis[3-(3,6-dimethyl-2-hydroxybenzyl)-2-hydroxy-5-methylphenyl]methane,
[3-(3,6-dimethyl-2-hydroxybenzyl)-2-hydroxy-5-methylphenyl],
[3-(2,5-dimethyl-4-hydroxybenzyl)-2-hydroxy-5-methylphenyl]methane,
Bis[3-(2,5-dimethyl-4-hydroxybenzyl)-2-hydroxy-5-methylphenyl]methane,
Bis[3-(3,5-dimethyl-4-hydroxybenzyl)-2-hydroxy-5-methylphenyl]methane,
Bis[3-(2-hydroxy-3,4,6-trimethylbenzyl)-2-hydroxy-5-methylphenyl]methane,
Bis[2-hydroxy-3-(4-hydroxy-2,3,5-trimethylbenzyl)-5-methylphenyl]methane,
4,4',4",4'"-tetrakis(4-hydroxyphenyl)-1,1'-bicyclohexyl,
2,2'-bis[4,4-bis(4-hydroxyphenyl)cyclohexyl]propane,
4,4',4",4'"-tetrakis(4-hydroxy-3-methylphenyl)-1,1'-bicyclohexyl,
Bis[3-(5-cyclohexyl-4-hydroxy-2-methylbenzyl)-4-hydroxy-5-methylphenyl]methane,
4,4',4",4'"-tetrakis(3,5-dimethyl-4-hydroxyphenyl)-1,1'-bicyclohexyl,
1,1-bis[3-(2-hydroxy-5-methylbenzyl)-5-cyclohexyl-4-hydroxyphenyl]cyclohexane,
1,1-bis[3-(3,5-dimethyl-4-hydroxybenzyl)-5-cyclohexyl-4-hydroxyphenyl]cyclohexane,
1,1-bis[3-(5-cyclohexyl-4-hydroxy-2-methylbenzyl)-5-cyclohexyl-4-hydroxyphenyl]cyclohexane,
4,6-bis[α-methyl-(4-hydroxyphenyl)benzyl-1,3-benzenediol,
2,2-bis[3-(4-hydroxy-3-methylbenzyl)-4-hydroxy-5-methylphenyl]propane,
2,6-bis[(3,5-dimethyl-4-hydroxyphenyl)benzyl]-4-[α-methyl-(3,5-dimethyl-4-hydroxyphenyl)benzyl]phenol,
4,4',4",4'"-tetrakis(4-hydroxy-3-isopropylphenyl)-1,1'-bicyclohexyl,
4,4'-bis[(3,4-dihydroxyphenyl)methylene]bis(2-isopropylphenol),
2,4,6-tris(4-hydroxybenzyl)-1,3-benzenediol,
4,6-bis(3,5-dimethyl-4-hydroxybenzyl)pyrogallol,
3,3'-[(2-hydroxyphenyl)methylene]bis(5-methylcatechol),
2,6-bis(2,4-dihydroxybenzyl)-4-ethylphenol,
2,4-bis(2,4-dihydroxybenzyl)-6-cyclohexylphenol,
2,6-bis(5-tert-butyl-2,3-dihydroxybenzyl)-4-methylphenol,
2,4,6-tris(3,5-dimethyl-4-hydroxybenzyl)resorcinol,
2,4,6-tris(3,5-dimethyl-2-hydroxybenzyl)resorcinol,
2,6-bis(2,4-dihydroxybenzyl)-3,4-dimethylphenol,
2,6-bis[3-(2-hydroxy-5-methylbenzyl)-2,5-dimethyl-4-hydroxybenzyl]-3,4-dimethylphenol,
4,6-bis(α-methyl-4-hydroxybenzyl)pyrogallol,
4,4'-[1-{4-[1-(3,5-bis(4-hydroxybenzyl)-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis[2,6-bis(4-hydroxybenzyl)phenol],
4,4'-[1-{4-[1-(3,5-bis(4-hydroxy-3-methylbenzyl)-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis[2,6-bis(4-hydroxy-3-methylbenzyl)phenol],
4,4'-[1-{4-[1-(3,5-bis(3,5-dimethyl-4-hydroxybenzyl)-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis[2,6-bis(3,5-dimethyl-4-hydroxybenzyl)phenol],
4,4'-[1-{4-[1-(3,5-bis(4-hydroxy-2,3,6-trimethylbenzyl)-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis[2,6-bis(4-hydroxy-2,3,6-trimethylbenzyl)phenol],
Bis[5-(2,4-dihydroxybenzyl)-4-hydroxy-3-methylphenyl]methane, bis[3-(2,4-dihydroxybenzyl)-2,5-dimethyl-4-hydroxyphenyl]methane,
Bis[3-(2,4-dihydroxy-3-methylbenzyl)-2,5-dimethyl-4-hydroxyphenyl]methane,
bis[5-(4-hydroxybenzyl)-2,3,4-trihydroxyphenyl]methane,
1,1-bis[5-(4-hydroxybenzoyl)-2,3,4-trihydroxyphenyl]ethane,
3,3',5,5'-tetrakis(4-hydroxybenzyl)-4,4'-dihydroxybiphenyl,
3,3',5,5'-tetrakis(4-hydroxy-3-methylbenzyl)-4,4'-dihydroxybiphenyl,
3,3',5,5'-tetrakis(2-hydroxy-5-methylbenzyl)-4,4'-dihydroxybiphenyl,
3,3',5,5'-tetrakis(3,5-dimethyl-4-hydroxybenzyl)-4,4'-dihydroxybiphenyl,
Bis[3-(α,α-bis(4-hydroxy-3-methylphenyl)methyl-4-hydroxyphenyl]methane,
Bis[3,5-bis(2-hydroxy-5-methylbenzyl)-4-hydroxyphenyl]methane,
4,4',4"-ethylidynetris{[2-(2-hydroxy-5-methyl)benzyl]-6-methylphenol},
2,2-bis[3,5-bis(2-hydroxy-5-methylphenylmethyl)phenyl]propane,
Bis[3-(α,α-bis(2,5-dimethyl-4-hydroxyphenyl)methyl-4-hydroxyphenyl]methane,
Bis[5-(3,5-dimethyl-4-hydroxybenzyl)-2,3,4-trihydroxyphenyl]methane,
Bis[3-(2,3,4-trihydroxybenzyl)-2,5-dimethyl-4-hydroxyphenyl]methane,
1,1-bis[3-(2,3,4-trihydroxybenzyl)-5-cyclohexyl-4-hydroxyphenyl]cyclohexane,
1,8,15,22-tetranonyl-3,5,10,12,17,19,24,26-octahydroxy[1,1,1,1]-metacyclophane,
4,4'-[1-{4-[1-(3,5-bis(4-hydroxy-2-methylbenzyl)-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis[2,6-bis(4-hydroxy-2-methylbenzyl)phenol],
4,4'-[1-{4-[1-(3,5-bis(2-hydroxy-5-methylbenzyl)-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis[2,6-bis(2-hydroxy-5-methylbenzyl)phenol],
4,4'-[1-{4-[1-(3,5-bis(3-ethyl-4-hydroxybenzyl)-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis[2,6-bis(3-ethyl-4-hydroxybenzyl)phenol],
4,4'-[1-{4-[1-(3,5-bis(3,5-dimethyl-2-hydroxyphenyl)-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis[2,6-bis(3,5-dimethyl-2-hydroxyphenyl)phenol],
4,4'-[1-{4-[1-(3,5-bis(4-hydroxy-3-isopropylphenyl)-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis[2,6-bis(4-hydroxy-3-isopropylphenyl)phenol],
Bis[3-(α,α-bis(3,5-dimethyl-4-hydroxyphenyl)methyl-4-hydroxyphenyl]methane,
Bis[3-(α,α-bis(5-cyclohexyl-4-hydroxy-2-methylphenyl)methyl-4-hydroxyphenyl]methane,
4,4'-[4-hydroxy-3,5-bis(2-hydroxybenzyl)methylene]bis[2,6-bis(2-hydroxybenzyl)]phenol,
4,4'-[4-hydroxy-3,5-bis(4-hydroxybenzyl)methylene]bis[2,6-bis(4-hydroxybenzyl)]phenol,
4,4',4"-ethylidynetris[2,6-bis(2-hydroxybenzyl)phenol],
4,4',4"-ethylidynetris[2,6-bis(4-hydroxybenzyl)phenol],
2,2-bis[3,5-bis(4-hydroxy-3-methylbenzyl)-4-hydroxyphenyl]propane,
1,8,15,22-tetraethyl-3,5,10,12,17,19,24,26-octahydroxy[1,1,1,1]-metacyclophane,
α,α',α",α'"-tetrakis(3,5-dimethyl-4-hydroxyphenyl)-1,4-dimethylbenzene,
4,4'-[1-{4-[1-(3,5-bis(2-hydroxy-5-isopropylphenyl)-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis[2,6-bis(2-hydroxy-5-isopropylphenyl)phenol],
4,4'-[1-{4-[1-(3,5-bis(4-hydroxy-2,3,5-trimethylphenyl)-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis[2,6-bis(4-hydroxy-2,3,5-trimethylphenyl)phenol],
4,4'-[1-{4-[1-(3,5-bis(3-sec-butyl-4-hydroxyphenyl)-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis[2,6-bis(3-sec-butyl-4-hydroxyphenyl)phenol],
4,4'-[1-{4-[1-(3,5-bis(3-tert-butyl-4-hydroxyphenyl)-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis[2,6-bis(3-tert-butyl-4-hydroxyphenyl)phenol],
2,6-bis{[3-(2,4-dihydroxybenzyl)-2,5-dimethyl-4-hydroxy]benzyl}-4-methylphenol,
1,1-bis[5-(2,4-dihydroxybenzyl)-3-cyclohexyl-4-hydroxyphenyl]cyclohexane,
1,1-bis[5-(2,3,4-trihydroxybenzyl)-3-cyclohexyl-4-hydroxyphenyl]cyclohexane,
Examples include 2,2-bis[4,4',4'',4''-tetrakis(3,5-dihydroxymethyl-4-hydroxyphenyl)cyclohexyl]propane.

Examples of carboxylic acids and their derivatives include:
3,5-di(α-methylbenzyl)salicylic acid,
4-(2-p-methoxyphenyloxyethoxy)salicylic acid,
4-hydroxyphenylbenzoic acid,
4-chlorobenzoic acid,
4-[2-(p-methoxyphenoxy)ethyloxy]salicylic acid,
4-[3-(p-tolylsulfonyl)propyloxy]salicylic acid,
5-[p-(2-p-methoxyphenoxyethoxy)cumyl]salicylic acid,
4-octyloxycarbonylaminosalicylic acid,
3,5-distyrenated salicylic acid,
N-(p-toluenesulfonyl)-glycine,
N-(p-toluenesulfonyl)-alanine,
N-(p-toluenesulfonyl)-β-alanine,
N-phenylaminocarbonyl-glycine,
N-phenylaminocarbonyl-valine,
N-(m-tolylaminocarbonyl)-phenylalanine,
N-(m-tolylaminocarbonyl)-cysteine-S-benzyl,
N-(m-tolylaminocarbonyl)-methionine,
N-(m-tolylaminocarbonyl)-tyrosine,
N-(p-tolylaminocarbonyl)-phenylalanine,
N-(p-tolylaminocarbonyl)-cysteine-S-benzyl,
N-(p-tolylaminocarbonyl)-methionine,
N-(p-tolylaminocarbonyl)-methionine,
N-(phenylaminocarbonyl)-methionine,
N-(p-tolylaminocarbonyl)-tyrosine,
2-O-(phenylaminocarbonyl)-mandelic acid,
2-O-(p-tolylaminocarbonyl)-mandelic acid,
2-O-(m-tolylaminocarbonyl)-mandelic acid,
2-O-(o-tolylaminocarbonyl)-mandelic acid,
2-O-(1-naphthylaminocarbonyl)-mandelic acid,
2-O-(3-isopropenyl-α,α-dimethylbenzylaminocarbonyl)-mandelic acid,
2-O-(benzylaminocarbonyl)-mandelic acid,
2-O-(phenethylaminocarbonyl)-mandelic acid,
2-O-(phenylaminocarbonyl)-lactic acid,
2-O-(p-tolylaminocarbonyl)-lactic acid,
2-O-(m-tolylaminocarbonyl)-lactic acid,
2-O-(o-tolylaminocarbonyl)-lactic acid,
2-O-(1-naphthylaminocarbonyl)-lactic acid,
2-O-(3-isopropenyl-α,α-dimethylbenzylaminocarbonyl)-lactic acid,
2-O-(benzylaminocarbonyl)-lactic acid,
An example is 2-O-(phenethylaminocarbonyl)-lactic acid.

Examples of acidic phosphate ester compounds include methyl acid phosphate, ethyl acid phosphate, butyl acid phosphate, butoxyethyl acid phosphate, 2-ethylhexyl acid phosphate, isodecyl acid phosphate, isotridecyl acid phosphate, oleyl acid phosphate, tetracosyl acid phosphate, monobutyl phosphate, dibutyl phosphate, monoisodecyl phosphate, bis(2-ethylhexyl)phosphate, etc.

The component (c) of the reaction medium that reversibly induces an electron donor-acceptor reaction between the components (a) and (b) in a specific temperature range will now be described.
Examples of the component (c) include alcohols, esters, ketones, ethers, and acid amides.
When the reversible thermochromic composition of the present invention is encapsulated in microcapsules for secondary processing, compounds having 10 or more carbon atoms are preferably used to stably retain the composition in the capsules, since low molecular weight compounds will evaporate out of the capsules when subjected to high heat treatment.

As alcohols, aliphatic monohydric saturated alcohols having 10 or more carbon atoms are effective, such as decyl alcohol, undecyl alcohol, dodecyl alcohol, tridecyl alcohol, tetradecyl alcohol, pentadecyl alcohol, hexadecyl alcohol, heptadecyl alcohol, octadecyl alcohol, eicosyl alcohol, and docosyl alcohol.

As esters, esters having 10 or more carbon atoms are effective, and examples thereof include esters obtained from any combination of a monovalent carboxylic acid having an aliphatic, alicyclic or aromatic ring and a monovalent alcohol having an aliphatic, alicyclic or aromatic ring, esters obtained from any combination of a polyvalent carboxylic acid having an aliphatic, alicyclic or aromatic ring and a monovalent alcohol having an aliphatic, alicyclic or aromatic ring, esters obtained from any combination of a monovalent carboxylic acid having an aliphatic, alicyclic or aromatic ring and a monovalent alcohol having an aliphatic, alicyclic or aromatic ring, and any combination of a monovalent carboxylic acid having an aliphatic, alicyclic or aromatic ring and a polyvalent alcohol having an aliphatic, alicyclic or aromatic ring. Examples of the esters include esters obtained by combining ethyl caprylate, octyl caprylate, stearyl caprylate, myristyl caprate, docosyl caprate, 2-ethylhexyl laurate, n-decyl laurate, 3-methylbutyl myristate, cetyl myristate, isopropyl palmitate, neopentyl palmitate, nonyl palmitate, cyclohexyl palmitate, n-butyl stearate, 2-methylbutyl stearate, 3,5,5-trimethylhexyl stearate, and stearic acid. n-Undecyl stearate, pentadecyl stearate, stearyl stearate, cyclohexylmethyl stearate, isopropyl behenate, hexyl behenate, lauryl behenate, behenyl behenate, cetyl benzoate, stearyl 4-tert-butylbenzoate, dimyristyl phthalate, distearyl phthalate, dimyristyl oxalate, dicetyl oxalate, dicetyl malonate, dilauryl succinate, dilauryl glutarate, diundecyl adipate, dilauryl azelate, di-(n-nonyl) sebacate, 1 Examples include 18-octadecylmethylenedicarboxylate dineopentyl, ethylene glycol dimyristate, propylene glycol dilaurate, propylene glycol distearate, hexylene glycol dipalmitate, 1,5-pentanediol distearate, 1,2,6-hexanetriol trimyristate, 1,4-cyclohexanediol didecyl, 1,4-cyclohexanedimethanol dimyristate, xylene glycol dicaprinate, and xylene glycol distearate.

Also effective are esters of saturated fatty acids and branched aliphatic alcohols, and ester compounds of unsaturated fatty acids or branched or substituted saturated fatty acids and branched aliphatic alcohols or aliphatic alcohols having 16 or more carbon atoms.
Examples of the ester compounds include 2-ethylhexyl butyrate, 2-ethylhexyl behenate, 2-ethylhexyl myristate, 2-ethylhexyl caprate, 3,5,5-trimethylhexyl laurate, 3,5,5-trimethylhexyl palmitate, 3,5,5-trimethylhexyl stearate, 2-methylbutyl caproate, 2-methylbutyl caprylate, 2-methylbutyl caprate, 1-ethylpropyl palmitate, 1-ethylpropyl stearate, 1-ethylpropyl behenate, laurate, 3,5,5-trimethylhexyl stearate, 3,5,5-trimethylhexyl stearate, 2-methylbutyl caproate, 2-methylbutyl caprylate, 1-ethylpropyl palmitate, 1-ethylpropyl stearate, 1-ethylpropyl behenate, laurate, 3,5,5-trimethylhexyl stea ... 1-Ethylhexyl phosphate, 1-ethylhexyl myristate, 1-ethylhexyl palmitate, 2-methylpentyl caproate, 2-methylpentyl caprylate, 2-methylpentyl caprate, 2-methylpentyl laurate, 2-methylbutyl stearate, 2-methylbutyl stearate, 3-methylbutyl stearate, 1-methylheptyl stearate, 2-methylbutyl behenate, 3-methylbutyl behenate, 1-methylheptyl stearate, 1-methylheptyl behenate, 1-ethylcaproate 1-ethylpentyl palmitate, 1-methylpropyl stearate, 1-methyloctyl stearate, 1-methylhexyl stearate, 1,1-dimethylpropyl laurate, 1-methylpentyl caprate, 2-methylhexyl palmitate, 2-methylhexyl stearate, 2-methylhexyl behenate, 3,7-dimethyloctyl laurate, 3,7-dimethyloctyl myristate, 3,7-dimethyloctyl palmitate, 3,7-dimethyloctyl stearate, 3,7-dimethyloctyl behenate Examples of such esters include 3,7-dimethyloctyl ester, stearyl oleate, behenyl oleate, stearyl linoleate, behenyl linoleate, 3,7-dimethyloctyl erucate, stearyl erucate, isostearyl erucate, cetyl isostearate, stearyl isostearate, 2-methylpentyl 12-hydroxystearate, 2-ethylhexyl 18-bromostearate, isostearyl 2-ketomyristate, 2-ethylhexyl 2-fluoromyristate, cetyl butyrate, stearyl butyrate, and behenyl butyrate.

Furthermore, in order to change color while exhibiting a large hysteresis characteristic in the color density-temperature curve and to impart color memory depending on temperature change, examples of carboxylate compounds that exhibit a ΔT value (melting point-cloud point) of 5°C or more and less than 50°C as described in JP-B-4-17154 include carboxylate compounds containing a substituted aromatic ring in the molecule, esters of carboxylic acids containing unsubstituted aromatic rings and aliphatic alcohols having 10 or more carbon atoms, carboxylate compounds containing a cyclohexyl group in the molecule, esters of fatty acids having 6 or more carbon atoms and unsubstituted aromatic alcohols or phenols, esters of fatty acids having 8 or more carbon atoms and branched aliphatic alcohols, esters of dicarboxylic acids and aromatic alcohols or branched aliphatic alcohols, dibenzyl cinnamate, heptyl stearate, didecyl adipate, dilauryl adipate, dimyristyl adipate, dicetyl adipate, distearyl adipate, trilaurin, trimyristin, tristearin, dimyristin, distearin, etc.

Also effective are fatty acid ester compounds obtained from an aliphatic monohydric alcohol having an odd number of carbon atoms of 9 or more and an aliphatic carboxylic acid having an even number of carbon atoms, and fatty acid ester compounds having a total of 17 to 23 carbon atoms obtained from n-pentyl alcohol or n-heptyl alcohol and an aliphatic carboxylic acid having an even number of carbon atoms of 10 to 16.
Examples of the fatty acid ester compound include n-pentadecyl acetate, n-tridecyl butyrate, n-pentadecyl butyrate, n-undecyl caproate, n-tridecyl caproate, n-pentadecyl caproate, n-nonyl caprylate, n-undecyl caprylate, n-tridecyl caprylate, n-pentadecyl caprylate, n-heptyl caprate, n-nonyl caprate, n-undecyl caprate, n-tridecyl caprate, n-pentadecyl caprate, n-pentyl laurate, n-heptyl laurate, n-nonyl laurate, n-undecyl laurate, n-tridecyl laurate, n-pentadecyl laurate, n-pentyl myristate, and n-heptyl myristate. Examples of the compound include n-nonyl myristate, n-undecyl myristate, n-tridecyl myristate, n-pentadecyl myristate, n-pentyl palmitate, n-heptyl palmitate, n-nonyl palmitate, n-undecyl palmitate, n-tridecyl palmitate, n-pentadecyl palmitate, n-nonyl stearate, n-undecyl stearate, n-tridecyl stearate, n-pentadecyl stearate, n-nonyl eicosanoate, n-undelsyl eicosanoate, n-tridecyl eicosanoate, n-pentadecyl eicosanoate, n-nonyl behenate, n-undecyl behenate, n-tridecyl behenate, and n-pentadecyl behenate.

As the ketones, aliphatic ketones having a total carbon number of 10 or more are effective, and examples thereof include 2-decanone, 3-decanone, 4-decanone, 2-undecanone, 3-undecanone, 4-undecanone, 5-undecanone, 2-dodecanone, 3-dodecanone, 4-dodecanone, 5-dodecanone, 2-tridecanone, 3-tridecanone, 2-tetradecanone, 2-pentadecanone, 8-pentadecanone, 2-hexadecanone, 3-hexadecanone, 9-heptadecanone, 2-pentadecanone, 2-octadecanone, 2-nonadecanone, 10-nonadecanone, 2-eicosanone, 11-eicosanone, 2-heneicosanone, 2-docosanone, laurone, and stearone.
Further, aryl alkyl ketones having a total carbon number of 12 to 24, for example, n-octadecanophenone, n-heptadecanophenone, n-hexadecanophenone, n-pentadecanophenone, n-tetradecanophenone, 4-n-dodecaacetophenone, n-tridecanophenone, 4-n-undecanoacetophenone, n-laurophenone, 4-n-decanoacetophenone, n-undecanophenone, 4-n-nonylacetophenone, n-decanophenone, 4-n-octylacetophenone, n ... Examples of acetophenone include 4-n-heptylacetophenone, n-octanophenone, 4-n-hexylacetophenone, 4-n-cyclohexylacetophenone, 4-tert-butylpropiophenone, n-heptaphenone, 4-n-pentylacetophenone, cyclohexyl phenyl ketone, benzyl-n-butyl ketone, 4-n-butylacetophenone, n-hexanophenone, 4-isobutylacetophenone, 1-acetonaphthone, 2-acetonaphthone, and cyclopentyl phenyl ketone.

As ethers, aliphatic ethers having a total of 10 or more carbon atoms are effective, and examples thereof include dipentyl ether, dihexyl ether, diheptyl ether, dioctyl ether, dinonyl ether, didecyl ether, diundecyl ether, didodecyl ether, ditridecyl ether, ditetradecyl ether, dipentadecyl ether, dihexadecyl ether, dioctadecyl ether, decanediol dimethyl ether, undecanediol dimethyl ether, dodecanediol dimethyl ether, tridecanediol dimethyl ether, decanediol diethyl ether, undecanediol diethyl ether, etc.

Examples of acid amides include acetamide, propionic acid amide, butyric acid amide, caproic acid amide, caprylic acid amide, capric acid amide, lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, oleic acid amide, erucic acid amide, benzamide, caproic acid anilide, caprylic acid anilide, capric acid anilide, lauric acid anilide, myristic acid anilide, palmitic acid anilide, stearic acid anilide, behenic acid anilide, oleic acid anilide, erucic acid anilide, caproic acid N-methylamide, caprylic ... acid N-methylamide, lauric acid N-methylamide, myristic acid N-methylamide, palmitic acid N-methylamide, stearic acid N-methylamide, behenic acid N-methylamide, oleic acid N-methylamide, erucic acid N-methylamide, lauric acid N-ethylamide, myristic acid N-ethylamide, palmitic acid N-ethylamide, stearic acid N-ethylamide, oleic acid N-ethylamide, lauric acid N-butylamide, myristic acid N-butylamide, palmitic acid N-butylamide, stearic acid N-butylamide, oleic acid N-butylamide, lauric acid N-octylamide amide, myristic acid N-octylamide, palmitic acid N-octylamide, stearic acid N-octylamide, oleic acid N-octylamide, lauric acid N-dodecylamide, myristic acid N-dodecylamide, palmitic acid N-dodecylamide, stearic acid N-dodecylamide, oleic acid N-dodecylamide, dilauric acid amide, dimyristic acid amide, dipalmitic acid amide, distearic acid amide, dioleic acid amide, trilauric acid amide, trimyristic acid amide, tripalmitic acid amide, tristearic acid amide, trioleic acid amide, succinic acid amide, adipic acid Examples of the amides include succinic acid N-methylamide, adipic acid N-methylamide, glutaric acid N-methylamide, malonic acid N-methylamide, azelaic acid N-methylamide, succinic acid N-ethylamide, adipic acid N-ethylamide, glutaric acid N-ethylamide, malonic acid N-ethylamide, azelaic acid N-ethylamide, succinic acid N-butylamide, adipic acid N-butylamide, glutaric acid N-butylamide, malonic acid N-butylamide, adipic acid N-octylamide, and adipic acid N-dodecylamide.

〔式中、Ｒ_１は水素原子又はメチル基を示し、ｍは０～２の整数を示し、Ｘ_１及びＸ_２のいずれか一方は－（ＣＨ_２）_ｎＯＣＯＲ_２又は－（ＣＨ_２）_ｎＣＯＯＲ_２、他方は水素原子を示し、ｎは０～２の整数を示し、Ｒ_２は炭素数４以上のアルキル基又はアルケニル基を示し、Ｙ_１及びＹ_２はそれぞれ独立して、水素原子、炭素数１～４のアルキル基、メトキシ基、ハロゲン原子のいずれかを示し、ｒ及びｐはそれぞれ独立して、１～３の整数を示す。〕
式（３）で示される化合物のうち、Ｒ_１が水素原子の場合、より広いヒステリシス幅を有する可逆熱変色性組成物が得られるため好ましく、さらにＲ_１が水素原子であり、且つ、ｍが０の場合がより好ましい。
なお、式（３）で示される化合物のうち、より好ましくは下記式（４）で示される化合物である。

（式中、Ｒは炭素数８以上のアルキル基又はアルケニル基を示し、好ましくは炭素数１０～２４のアルキル基であり、より好ましくは炭素数１２～２２のアルキル基である。）
式（４）で示される化合物としては、例えば、オクタン酸４－ベンジルオキシフェニルエチル、ノナン酸４－ベンジルオキシフェニルエチル、デカン酸４－ベンジルオキシフェニルエチル、ウンデカン酸４－ベンジルオキシフェニルエチル、ドデカン酸４－ベンジルオキシフェニルエチル、トリデカン酸４－ベンジルオキシフェニルエチル、テトラデカン酸４－ベンジルオキシフェニルエチル、ペンタデカン酸４－ベンジルオキシフェニルエチル、ヘキサデカン酸４－ベンジルオキシフェニルエチル、ヘプタデカン酸４－ベンジルオキシフェニルエチル、オクタデカン酸４－ベンジルオキシフェニルエチル等を例示できる。 Furthermore, the component (iii) may be a compound represented by the following formula (3).

[In the formula, _R1 represents a hydrogen atom or a methyl group, m represents an integer of 0 to 2, one of _X1 and _X2 is -( _CH2 ) _nOCOR2 or -( _CH2 ) _{nCOOR2 , and} the other represents a hydrogen atom, n represents an integer of 0 to 2, _R2 represents an alkyl group or an alkenyl group having 4 or more carbon atoms, _Y1 and _Y2 each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a methoxy group, or a halogen atom, and r and p each independently represent an integer of 1 to 3.]
Of the compounds represented by formula (3), when R ₁ is a hydrogen atom, a reversible thermochromic composition having a wider hysteresis width can be obtained, which is preferable, and further, when R ₁ is a hydrogen atom and m is 0, it is more preferable.
Among the compounds represented by formula (3), a compound represented by the following formula (4) is more preferable.

(In the formula, R represents an alkyl group or alkenyl group having 8 or more carbon atoms, preferably an alkyl group having 10 to 24 carbon atoms, and more preferably an alkyl group having 12 to 22 carbon atoms.)
Examples of the compound represented by formula (4) include 4-benzyloxyphenylethyl octanoate, 4-benzyloxyphenylethyl nonanoate, 4-benzyloxyphenylethyl decanoate, 4-benzyloxyphenylethyl undecanoate, 4-benzyloxyphenylethyl dodecanoate, 4-benzyloxyphenylethyl tridecanoate, 4-benzyloxyphenylethyl tetradecanoate, 4-benzyloxyphenylethyl pentadecanoate, 4-benzyloxyphenylethyl hexadecanoate, 4-benzyloxyphenylethyl heptadecanoate, and 4-benzyloxyphenylethyl octadecanoate.

（式中、Ｒは炭素数８以上のアルキル基又はアルケニル基を示し、ｍ及びｎはそれぞれ独立して、１～３の整数を示し、Ｘ及びＹはそれぞれ独立して、水素原子、炭素数１～４のアルキル基、炭素数１～４のアルコキシ基、ハロゲン原子のいずれかを示す。）
式（５）で示される化合物としては、例えば、オクタン酸１，１－ジフェニルメチル、ノナン酸１，１－ジフェニルメチル、デカン酸１，１－ジフェニルメチル、ウンデカン酸１，１－ジフェニルメチル、ドデカン酸１，１－ジフェニルメチル、トリデカン酸１，１－ジフェニルメチル、テトラデカン酸１，１－ジフェニルメチル、ペンタデカン酸１，１－ジフェニルメチル、ヘキサデカン酸１，１－ジフェニルメチル、ヘプタデカン酸１，１－ジフェニルメチル、オクタデカン酸１，１－ジフェニルメチル等を例示できる。 Furthermore, the component (iii) may be a compound represented by the following formula (5).

(In the formula, R represents an alkyl group or alkenyl group having 8 or more carbon atoms, m and n each independently represent an integer from 1 to 3, and X and Y each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom.)
Examples of the compound represented by formula (5) include 1,1-diphenylmethyl octanoate, 1,1-diphenylmethyl nonanoate, 1,1-diphenylmethyl decanoate, 1,1-diphenylmethyl undecanoate, 1,1-diphenylmethyl dodecanoate, 1,1-diphenylmethyl tridecanoate, 1,1-diphenylmethyl tetradecanoate, 1,1-diphenylmethyl pentadecanoate, 1,1-diphenylmethyl hexadecanoate, 1,1-diphenylmethyl heptadecanoate, and 1,1-diphenylmethyl octadecanoate.

（式中、Ｘは水素原子、炭素数１～４のアルキル基、メトキシ基、ハロゲン原子のいずれかを示し、ｍは１～３の整数を示し、ｎは１～２０の整数を示す。）
式（６）で示される化合物としては、例えば、マロン酸と２－〔４－(４－クロロベンジルオキシ）フェニル〕エタノールとのジエステル、こはく酸と２－（４－ベンジルオキシフェニル）エタノールとのジエステル、こはく酸と２－〔４－(３－メチルベンジルオキシ）フェニル〕エタノールとのジエステル、グルタル酸と２－（４－ベンジルオキシフェニル）エタノールとのジエステル、グルタル酸と２－〔４－(４－クロロベンジルオキシ）フェニル〕エタノールとのジエステル、アジピン酸と２－（４－ベンジルオキシフェニル）エタノールとのジエステル、ピメリン酸と２－（４－ベンジルオキシフェニル）エタノールとのジエステル、スベリン酸と２－（４－ベンジルオキシフェニル）エタノールとのジエステル、スベリン酸と２－〔４－(３－メチルベンジルオキシ）フェニル〕エタノールとのジエステル、スベリン酸と２－〔４－(４－クロロベンジルオキシ）フェニル〕エタノールとのジエステル、スベリン酸と２－〔４－(２，４－ジクロロベンジルオキシ）フェニル〕エタノールとのジエステル、アゼライン酸と２－（４－ベンジルオキシフェニル）エタノールとのジエステル、セバシン酸と２－（４－ベンジルオキシフェニル）エタノールとのジエステル、１，１０－デカンジカルボン酸と２－（４－ベンジルオキシフェニル）エタノールとのジエステル、１，１８-オクタデカンジカルボン酸と２－（４－ベンジルオキシフェニル）エタノールとのジエステル、１，１８－オクタデカンジカルボン酸と２－〔４－(２－メチルベンジルオキシ）フェニル〕エタノールとのジエステル等を例示できる。 Furthermore, the component (iii) may be a compound represented by the following formula (6).

(In the formula, X represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a methoxy group, or a halogen atom, m represents an integer of 1 to 3, and n represents an integer of 1 to 20.)
Examples of the compound represented by formula (6) include a diester of malonic acid and 2-[4-(4-chlorobenzyloxy)phenyl]ethanol, a diester of succinic acid and 2-(4-benzyloxyphenyl)ethanol, a diester of succinic acid and 2-[4-(3-methylbenzyloxy)phenyl]ethanol, a diester of glutaric acid and 2-(4-benzyloxyphenyl)ethanol, a diester of glutaric acid and 2-[4-(4-chlorobenzyloxy)phenyl]ethanol, a diester of adipic acid and 2-(4-benzyloxyphenyl)ethanol, a diester of pimelic acid and 2-(4-benzyloxyphenyl)ethanol, a diester of suberic acid and 2-(4-benzyloxyphenyl)ethanol, a diester of suberic acid and 2-[4-(3-methyl Examples of the diester include a diester of suberic acid and 2-[4-(4-chlorobenzyloxy)phenyl]ethanol, a diester of suberic acid and 2-[4-(2,4-dichlorobenzyloxy)phenyl]ethanol, a diester of azelaic acid and 2-(4-benzyloxyphenyl)ethanol, a diester of sebacic acid and 2-(4-benzyloxyphenyl)ethanol, a diester of 1,10-decanedicarboxylic acid and 2-(4-benzyloxyphenyl)ethanol, a diester of 1,18-octadecanedicarboxylic acid and 2-(4-benzyloxyphenyl)ethanol, and a diester of 1,18-octadecanedicarboxylic acid and 2-[4-(2-methylbenzyloxy)phenyl]ethanol.

（式中、Ｒは炭素数１～２１のアルキル基又はアルケニル基を示し、ｎは１～３の整数を示す。）
式（７）で示される化合物としては、例えば、１，３－ビス（２－ヒドロキシエトキシ）ベンゼンとカプリン酸とのジエステル、１，３－ビス（２－ヒドロキシエトキシ）ベンゼンとウンデカン酸とのジエステル、１，３－ビス（２－ヒドロキシエトキシ）ベンゼンとラウリン酸とのジエステル、１，３－ビス（２－ヒドロキシエトキシ）ベンゼンとミリスチン酸とのジエステル、１，４－ビス（ヒドロキシメトキシ）ベンゼンと酪酸とのジエステル、１，４－ビス（ヒドロキシメトキシ）ベンゼンとイソ吉草酸とのジエステル、１，４－ビス（２－ヒドロキシエトキシ）ベンゼンと酢酸とのジエステル、１，４－ビス（２－ヒドロキシエトキシ）ベンゼンとプロピオン酸とのジエステル、１，４－ビス（２－ヒドロキシエトキシ）ベンゼンと吉草酸とのジエステル、１，４－ビス（２－ヒドロキシエトキシ）ベンゼンとカプロン酸とのジエステル、１，４－ビス（２－ヒドロキシエトキシ）ベンゼンとカプリル酸とのジエステル、１，４－ビス（２－ヒドロキシエトキシ）ベンゼンとカプリン酸とのジエステル、１，４－ビス（２－ヒドロキシエトキシ）ベンゼンとラウリン酸とのジエステル、１，４－ビス（２－ヒドロキシエトキシ）ベンゼンとミリスチン酸とのジエステル等を例示できる。 Furthermore, the component (iii) may be a compound represented by the following formula (7).

(In the formula, R represents an alkyl group or alkenyl group having 1 to 21 carbon atoms, and n represents an integer of 1 to 3.)
Examples of the compound represented by formula (7) include a diester of 1,3-bis(2-hydroxyethoxy)benzene and capric acid, a diester of 1,3-bis(2-hydroxyethoxy)benzene and undecanoic acid, a diester of 1,3-bis(2-hydroxyethoxy)benzene and lauric acid, a diester of 1,3-bis(2-hydroxyethoxy)benzene and myristic acid, a diester of 1,4-bis(hydroxymethoxy)benzene and butyric acid, a diester of 1,4-bis(hydroxymethoxy)benzene and isovaleric acid, and a diester of 1,4-bis(2-hydroxyethoxy)benzene and acetic acid. Examples of such esters include diesters of 1,4-bis(2-hydroxyethoxy)benzene and propionic acid, diesters of 1,4-bis(2-hydroxyethoxy)benzene and valeric acid, diesters of 1,4-bis(2-hydroxyethoxy)benzene and caproic acid, diesters of 1,4-bis(2-hydroxyethoxy)benzene and caprylic acid, diesters of 1,4-bis(2-hydroxyethoxy)benzene and capric acid, diesters of 1,4-bis(2-hydroxyethoxy)benzene and lauric acid, and diesters of 1,4-bis(2-hydroxyethoxy)benzene and myristic acid.

（式中、Ｘは水素原子、炭素数１～４のアルキル基、炭素数１～４のアルコキシ基、ハロゲン原子のいずれかを示し、ｍは１～３の整数を示し、ｎは１～２０の整数を示す。）
式（８）で示される化合物としては、例えば、こはく酸と２－フェノキシエタノールとのジエステル、スベリン酸と２－フェノキシエタノールとのジエステル、セバシン酸と２－フェノキシエタノールとのジエステル、１，１０－デカンジカルボン酸と２－フェノキシエタノールとのジエステル、１，１８－オクタデカンジカルボン酸と２－フェノキシエタノールとのジエステル等を例示できる。 Furthermore, the component (iii) may be a compound represented by the following formula (8).

(In the formula, X represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom, m represents an integer of 1 to 3, and n represents an integer of 1 to 20.)
Examples of the compound represented by formula (8) include a diester of succinic acid and 2-phenoxyethanol, a diester of suberic acid and 2-phenoxyethanol, a diester of sebacic acid and 2-phenoxyethanol, a diester of 1,10-decanedicarboxylic acid and 2-phenoxyethanol, and a diester of 1,18-octadecanedicarboxylic acid and 2-phenoxyethanol.

（式中、Ｒは炭素数４～２２のアルキル基、シクロアルキルアルキル基、シクロアルキル基、炭素数４～２２のアルケニル基のいずれかを示し、Ｘは水素原子、炭素数１～４のアルキル基、炭素数１～４のアルコキシ基、ハロゲン原子のいずれかを示し、ｎは０又は１を示す。）
式（９）で示される化合物としては、例えば、４－フェニル安息香酸デシル、４－フェニル安息香酸ラウリル、４－フェニル安息香酸ミリスチル、４－フェニル安息香酸シクロヘキシルエチル、４－ビフェニル酢酸オクチル、４－ビフェニル酢酸ノニル、４－ビフェニル酢酸デシル、４－ビフェニル酢酸ラウリル、４－ビフェニル酢酸ミリスチル、４－ビフェニル酢酸トリデシル、４－ビフェニル酢酸ペンタデシル、４－ビフェニル酢酸セチル、４－ビフェニル酢酸シクロペンチル、４－ビフェニル酢酸シクロヘキシルメチル、４－ビフェニル酢酸ヘキシル、４－ビフェニル酢酸シクロヘキシルメチル等を例示できる。 Furthermore, the component (iii) may be a compound represented by the following formula (9).

(In the formula, R represents any one of an alkyl group having 4 to 22 carbon atoms, a cycloalkylalkyl group, a cycloalkyl group, and an alkenyl group having 4 to 22 carbon atoms; X represents any one of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and a halogen atom; and n represents 0 or 1.)
Examples of the compound represented by formula (9) include decyl 4-phenylbenzoate, lauryl 4-phenylbenzoate, myristyl 4-phenylbenzoate, cyclohexylethyl 4-phenylbenzoate, octyl 4-biphenylacetate, nonyl 4-biphenylacetate, decyl 4-biphenylacetate, lauryl 4-biphenylacetate, myristyl 4-biphenylacetate, tridecyl 4-biphenylacetate, pentadecyl 4-biphenylacetate, cetyl 4-biphenylacetate, cyclopentyl 4-biphenylacetate, cyclohexylmethyl 4-biphenylacetate, hexyl 4-biphenylacetate, and cyclohexylmethyl 4-biphenylacetate.

（式中、Ｒは炭素数３～１８のアルキル基又は炭素数３～１８の脂肪族アシル基を示し、Ｘは水素原子、炭素数１～３のアルキル基、炭素数１又は２のアルコキシ基、ハロゲン原子のいずれかを示し、Ｙは水素原子又はメチル基を示し、Ｚは水素原子、炭素数１～４のアルキル基、炭素数１又は２のアルコキシ基、ハロゲン原子のいずれかを示す。）
式（１０）で示される化合物としては、例えば、４－ブトキシ安息香酸フェノキシエチル、４－ペンチルオキシ安息香酸フェノキシエチル、４－テトラデシルオキシ安息香酸フェノキシエチル、４－ヒドロキシ安息香酸フェノキシエチルとドデカン酸とのエステル、バニリン酸フェノキシエチルのドデシルエーテル等を例示できる。 Furthermore, the component (iii) may be a compound represented by the following formula (10).

(In the formula, R represents an alkyl group having 3 to 18 carbon atoms or an aliphatic acyl group having 3 to 18 carbon atoms; X represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 or 2 carbon atoms, or a halogen atom; Y represents a hydrogen atom or a methyl group; and Z represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 or 2 carbon atoms, or a halogen atom.)
Examples of the compound represented by formula (10) include phenoxyethyl 4-butoxybenzoate, phenoxyethyl 4-pentyloxybenzoate, phenoxyethyl 4-tetradecyloxybenzoate, an ester of phenoxyethyl 4-hydroxybenzoate with dodecanoic acid, and dodecyl ether of phenoxyethyl vanillate.

（式中、Ｒは炭素数４～２２のアルキル基、炭素数４～２２のアルケニル基、シクロアルキルアルキル基、シクロアルキル基のいずれかを示し、Ｘは水素原子、アルキル基、アルコキシ基、ハロゲン原子のいずれかを示し、Ｙは水素原子、アルキル基、アルコキシ基、ハロゲン原子のいずれかを示し、ｎは０又は１を示す。）
式（１１）で示される化合物としては、例えば、４－ヒドロキシ安息香酸オクチルの安息香酸エステル、４－ヒドロキシ安息香酸デシルの安息香酸エステル、４－ヒドロキシ安息香酸ヘプチルの４－メトキシ安息香酸エステル、４－ヒドロキシ安息香酸ドデシルの２－メトキシ安息香酸エステル、４－ヒドロキシ安息香酸シクロヘキシルメチルの安息香酸エステル等を例示できる。 Furthermore, the component (iii) may be a compound represented by the following formula (11).

(In the formula, R represents any one of an alkyl group having 4 to 22 carbon atoms, an alkenyl group having 4 to 22 carbon atoms, a cycloalkylalkyl group, and a cycloalkyl group; X represents any one of a hydrogen atom, an alkyl group, an alkoxy group, and a halogen atom; Y represents any one of a hydrogen atom, an alkyl group, an alkoxy group, and a halogen atom; and n represents 0 or 1.)
Examples of the compound represented by formula (11) include a benzoate ester of octyl 4-hydroxybenzoate, a benzoate ester of decyl 4-hydroxybenzoate, a 4-methoxybenzoate ester of heptyl 4-hydroxybenzoate, a 2-methoxybenzoate ester of dodecyl 4-hydroxybenzoate, and a benzoate ester of cyclohexylmethyl 4-hydroxybenzoate.

（式中、Ｒは炭素数３～１８のアルキル基、炭素数６～１１のシクロアルキルアルキル基、炭素数５～７のシクロアルキル基、炭素数３～１８のアルケニル基のいずれかを示し、Ｘは水素原子、炭素数１～４のアルキル基、炭素数１～３のアルコキシ基、ハロゲン原子のいずれかを示し、Ｙは水素原子、炭素数１～４のアルキル基、メトキシ基、エトキシ基、ハロゲン原子のいずれかを示す。）
式（１２）で示される化合物としては、例えば、４－ヒドロキシ安息香酸ノニルのフェノキシエチルエーテル、４－ヒドロキシ安息香酸デシルのフェノキシエチルエーテル、４－ヒドロキシ安息香酸ウンデシルのフェノキシエチルエーテル、バニリン酸ドデシルのフェノキシエチルエーテル等を例示できる。 Furthermore, the component (iii) may be a compound represented by the following formula (12).

(In the formula, R represents any one of an alkyl group having 3 to 18 carbon atoms, a cycloalkylalkyl group having 6 to 11 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, and an alkenyl group having 3 to 18 carbon atoms; X represents any one of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, and a halogen atom; and Y represents any one of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a methoxy group, an ethoxy group, and a halogen atom.)
Examples of the compound represented by formula (12) include phenoxyethyl ether of nonyl 4-hydroxybenzoate, phenoxyethyl ether of decyl 4-hydroxybenzoate, phenoxyethyl ether of undecyl 4-hydroxybenzoate, and phenoxyethyl ether of dodecyl vanillate.

（式中、Ｒは炭素数３～８のシクロアルキル基又は炭素数４～９のシクロアルキルアルキル基を示し、ｎは１～３の整数を示す。）
式（１３）で示される化合物としては、例えば、１，３－ビス（２－ヒドロキシエトキシ）ベンゼンとシクロヘキサンカルボン酸とのジエステル、１，４－ビス（２－ヒドロキシエトキシ）ベンゼンとシクロヘキサンプロピオン酸とのジエステル、１，３－ビス（２－ヒドロキシエトキシ）ベンゼンとシクロヘキサンプロピオン酸とのジエステル等を例示できる。 Furthermore, the component (iii) may be a compound represented by the following formula (13).

(In the formula, R represents a cycloalkyl group having 3 to 8 carbon atoms or a cycloalkylalkyl group having 4 to 9 carbon atoms, and n represents an integer of 1 to 3.)
Examples of the compound represented by formula (13) include a diester of 1,3-bis(2-hydroxyethoxy)benzene and cyclohexanecarboxylic acid, a diester of 1,4-bis(2-hydroxyethoxy)benzene and cyclohexanepropionic acid, and a diester of 1,3-bis(2-hydroxyethoxy)benzene and cyclohexanepropionic acid.

（式中、Ｒは炭素数３～１７のアルキル基、炭素数３～８のシクロアルキル基、炭素数５～８のシクロアルキルアルキル基のいずれかを示し、Ｘは水素原子、炭素数１～５のアルキル基、メトキシ基、エトキシ基、ハロゲン原子のいずれかを示し、ｎは１～３の整数を示す。）
式（１４）で示される化合物としては、例えば、４－フェニルフェノールエチレングリコールエーテルとシクロヘキサンカルボン酸とのジエステル、４－フェニルフェノールジエチレングリコールエーテルとラウリン酸とのジエステル、４－フェニルフェノールトリエチレングリコールエーテルとシクロヘキサンカルボン酸とのジエステル、４－フェニルフェノールエチレングリコールエーテルとオクタン酸とのジエステル、４－フェニルフェノールエチレングリコールエーテルとノナン酸とのジエステル、４－フェニルフェノールエチレングリコールエーテルとデカン酸とのジエステル、４－フェニルフェノールエチレングリコールエーテルとミリスチン酸とのジエステル等を例示できる。 Furthermore, the component (iii) may be a compound represented by the following formula (14).

(In the formula, R represents any one of an alkyl group having 3 to 17 carbon atoms, a cycloalkyl group having 3 to 8 carbon atoms, and a cycloalkylalkyl group having 5 to 8 carbon atoms; X represents any one of a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a methoxy group, an ethoxy group, and a halogen atom; and n represents an integer of 1 to 3.)
Examples of the compound represented by formula (14) include a diester of 4-phenylphenol ethylene glycol ether and cyclohexane carboxylic acid, a diester of 4-phenylphenol diethylene glycol ether and lauric acid, a diester of 4-phenylphenol triethylene glycol ether and cyclohexane carboxylic acid, a diester of 4-phenylphenol ethylene glycol ether and octanoic acid, a diester of 4-phenylphenol ethylene glycol ether and nonanoic acid, a diester of 4-phenylphenol ethylene glycol ether and decanoic acid, and a diester of 4-phenylphenol ethylene glycol ether and myristic acid.

The reversible thermochromic composition of the present invention is a compatible solution containing the above-mentioned components (A), (B), and (C) as essential components. The ratio of each component depends on the concentration, discoloration temperature, discoloration form, and type of each component, but the component ratio that generally provides the desired properties is in the range of 1 part of component (A) to 0.1 to 100, preferably 0.1 to 50, and more preferably 0.5 to 20, of component (B), and 5 to 200, preferably 5 to 100, and more preferably 10 to 100, of component (C) (all the above ratios are in parts by mass).

Furthermore, the reversible thermochromic composition may contain various light stabilizers, if necessary.
The light stabilizer is contained to prevent photodegradation of the reversible thermochromic composition consisting of components (A), (B), and (C), and is blended in a ratio of 0.3 to 24% by mass, preferably 0.3 to 16% by mass, per 1% by mass of component (A). Among the light stabilizers, the ultraviolet absorber effectively blocks ultraviolet rays contained in sunlight and the like, and prevents photodegradation caused by the excited state due to the photoreaction of component (A). Furthermore, the antioxidant, singlet oxygen quencher, superoxide anion quencher, ozone quencher, etc. suppress oxidation reactions caused by light.
The light stabilizers may be used alone or in combination of two or more kinds.

Examples of ultraviolet absorbing agents among light stabilizers include:
2,4-hydroxybenzophenone,
2-hydroxy-4-methoxybenzophenone,
2,2'-dihydroxy-4,4'-dimethoxybenzophenone,
2,2',4,4'-tetrahydroxybenzophenone,
2-hydroxy-4-methoxybenzophenone-5-sulfonic acid,
2-hydroxy-4-octyloxybenzophenone,
Bis-(5-benzoyl-4-hydroxy-2-methoxyphenyl)-methane,
2-(3',5'-di-tert-amyl-2'-hydroxyphenyl)benzophenone,
4-dodecyloxy-2-hydroxybenzophenone,
2-hydroxy-4-octadecyloxybenzophenone,
2,2'-dihydroxy-4-methoxybenzophenone,
4-benzyloxy-2-hydroxybenzophenone,
Benzophenone-based ultraviolet absorbers such as 2-(3',5'-di-tert-amyl-2'-hydroxyphenyl)benzophenone,
Phenyl salicylate,
4-tert-butylphenyl salicylate,
4-octylphenyl salicylate,
2,4-di-tert-butylphenyl-4-hydroxybenzoate,
1-hydroxybenzoate,
3-tert-butyl-1-hydroxybenzoate,
1-hydroxy-3-tert-octyl benzoate,
Salicylic acid-based ultraviolet absorbers such as resorcinol monobenzoate,
2-ethyl-2-cyano-3,3'-diphenylacrylate,
2-ethylhexyl-2-cyano-3,3'-diphenylacrylate,
Cyanoacrylate ultraviolet absorbers such as 2-ethylhexyl-2-cyano-3-phenylcinnate,
2-(5-tert-butyl-2-hydroxyphenyl)benzotriazole,
2-(2-hydroxy-5-methylphenyl)benzotriazole,
2-[3,5-bis(a,a-dimethylbenzyl)-2-hydroxyphenyl]-2H-benzotriazole,
2-(3,5-di-tert-butyl-2-hydroxyphenyl)benzotriazole,
2-(3-tert-butyl-2-hydroxy-5-methylphenyl)-5-chlorobenzotriazole,
2-(3,5-di-tert-butyl-2-hydroxyphenyl)-5-chlorobenzotriazole,
2-(3,5-di-tert-amyl-2-hydroxyphenyl)benzotriazole,
β-[3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl]propionic acid-polyethylene glycol 300 ester,
2-(3-dodecyl-2-hydroxy-5-methylphenyl)benzotriazole,
Bis{β-[3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl]}propionic acid-polyethylene glycol 300 ester,
2-(3-tert-butyl-2-hydroxyphenyl-5-propyloctylate)-5-chlorobenzotriazole,
2-[2-hydroxyphenyl-3,5-di-(1,1'-dimethylbenzyl)phenyl]-2H-benzotriazole,
2-(2-hydroxy-5-tert-octylphenyl)-2H-benzotriazole,
2-(3-tert-butyl-5-octyloxycarbonylethyl-2-hydroxyphenyl)benzotriazole,
2-(2-hydroxy-5-tetraoctylphenyl)benzotriazole,
2-(2-hydroxy-4-octoxyphenyl)benzotriazole,
2-[2'-hydroxy-3'-(3",4",5",6"-tetrahydrophthalimidomethyl)-5'-methylphenyl]benzotriazole,
benzotriazole-based ultraviolet absorbers such as 2-(5-tert-butyl-2-hydroxyphenyl)benzotriazole;
Ethanediamide-N-(2-ethoxyphenyl)-N'-(4-isododecylphenyl),
oxalic acid anilide ultraviolet absorbers such as 2,2,4,4-tetramethyl-20-(β-lauryl-oxycarbonyl)-ethyl-7-oxa-3,20-diazodispiro(5,1,11,2)heneicoic acid-21-one;
2,4-diphenyl-6-(2-hydroxy-4-methoxyphenyl)-1,3,5-triazine,
2,4-diphenyl-6-(2-hydroxy-4-ethoxyphenyl)-1,3,5-triazine,
2,4-diphenyl-6-(2-hydroxy-4-propoxyphenyl)-1,3,5-triazine,
2,4-diphenyl-6-(2-hydroxy-4-butoxyphenyl)-1,3,5-triazine,
2,4-diphenyl-6-(2-hydroxy-4-hexyloxyphenyl)-1,3,5-triazine,
2,4-diphenyl-6-(2-hydroxy-4-pentoxyphenyl)-1,3,5-triazine,
2,4-diphenyl-6-(2-hydroxy-4-octyloxyphenyl)-1,3,5-triazine,
2,4-diphenyl-6-(2-hydroxy-4-dodecyloxyphenyl)-1,3,5-triazine,
2,4-diphenyl-6-(2-hydroxy-4-benzyloxyphenyl)-1,3,5-triazine,
2,4-diphenyl-6-[2-hydroxy-4-(2-butoxyethoxy)phenyl]-1,3,5-triazine,
2,4-di-p-trail-6-(2-hydroxy-4-methoxyphenyl)-1,3,5-triazine,
2,4-di-p-trail-6-(2-hydroxy-4-propoxyphenyl)-1,3,5-triazine,
2,4-di-p-trail-6-(2-hydroxy-4-butoxyphenyl)-1,3,5-triazine,
2,4-di-p-trail-6-(2-hydroxy-4-hexyloxyphenyl)-1,3,5-triazine,
2,4-di-p-trail-6-(2-hydroxy-4-pentoxyphenyl)-1,3,5-triazine,
2,4-di-p-trail-6-(2-hydroxy-4-octyloxyphenyl)-1,3,5-triazine,
2,4-di-p-trail-6-(2-hydroxy-4-benzyloxyphenyl)-1,3,5-triazine,
2,4-di-p-trail-6-[2-hydroxy-4-(2-hexyloxyethoxy)phenyl]-1,3,5-triazine,
2-{4-[(2-hydroxy-3-dodecyloxypropyl)oxy]-2-hydroxyphenyl}-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine,
2-{4-[(2-hydroxy-3-tridecyloxypropyl)oxy]-2-hydroxyphenyl}-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine,
2-[4-{[2-hydroxy-3-(2'-ethyl)hexyl]oxy}-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine,
2,4-bis(2-hydroxy-4-butyloxyphenyl)-6-[2,4-bis(butyloxyphenyl)]-1,3,5-triazine,
Examples include triazine-based ultraviolet absorbers such as 2-{2-hydroxy-4-[(1-octyloxycarbonylethoxy)phenyl]}-4,6-bis(4-phenylphenyl)-1,3,5-triazine.

Examples of antioxidants (antiaging agents) include:
Dimethyl succinate-1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate,
poly{[6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2-4-diyl][(2,2,6,6-tetramethyl-4-piperidyl)imino]hexamethylene[(2,2,6,6-tetramethyl-4-piperidyl)imino]}hexamethylene,
2-(3,5-di-tert-butyl-4-hydroxybenzyl)-2-n-butylmalonate bis(1,2,2,6,6-pentapetyl-4-piperidyl),
N,N'-bis(3-aminopropyl)ethylenediamine-2,4-bis[N-butyl-N-(1,2,2,6,6-pentapetyl-4-piperidyl)amino]-6-chloro-1,3,5-triazine condensate,
Bis(1,2,2,6,6-pentamethyl-4-piperidylsebacic acid),
4-benzoyloxy-2,2,6,6-tetramethylpiperidine,
bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate,
hindered amine antioxidants such as 8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro[4,5]decane-2,4-dione,
2,6-di-tert-butyl-4-methylphenol,
2-tert-butyl-4-methoxyphenol,
2,6-di-tert-butyl-4-ethylphenol,
octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate,
2,2-methylenebis(4-methyl-6-tert-butylphenol),
4,4-thiobis(2-methyl-6-tert-butylphenol),
2,2-thiobis(4-methyl-6-tert-butylphenol),
4,4-butylidenebis(3-methyl-6-tert-butylphenol),
3,9-bis{1,1-dimethyl-2-[β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl},
2,4,8,10-tetraoxaspiro[5,5]undecane,
1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane,
1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene,
Tetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]methane,
2,2-ethylenebis(4,6-di-tert-butylphenol),
Bis[3,3-bis-(4'-hydroxy-3'-tert-butylphenyl)butyric acid]glycol ester,
1,3,5-tris(3',5'-di-tert-butyl-4'-hydroxybenzyl)-S-triazine-2,4,6-[1H,3H,5H]-trione,
Tocopherol,
1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanurate,
Pentaerythritol tetrakis(3-lauryl thiopropionate),
Triethylene glycol bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate],
1,6-hexadiol-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate],
2,2-thioethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate],
N,N'-hexamethylenebis(3,5-tert-butyl-4-hydroxy-hydrocinnamamide),
Tris-(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate,
2,2,4-trimethyl-1,2-hydroquinone,
Styryl phenol,
2,5-di-tert-butylhydroquinone,
phenolic antioxidants such as bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate;
Dilauryl-3,3'-thiodipropionate,
Dimyristyl-3,3'-thiodipropionate,
Distearyl-3,3'-thiodipropionate,
Sulfur-based antioxidants such as stearyl thiopropylamide,
Tris(2,4-di-tert-butylphenyl)phosphite,
Bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite,
3,5-di-tert-butyl-4-hydroxy-benzylphosphonate-diethyl ester,
triphenyl phosphite,
diphenyl isodecyl phosphite,
phenyl isodecyl phosphite,
4,4'-butylidene-bis(3-methyl-6-tert-butylphenylditridecyl)phosphite,
Octadecyl phosphite,
Tris(nonylphenyl)phosphite,
Diisodecyl pentaerythritol diphosphite,
9,10-dihydroxy-9-oxa-10-phosphaphenanthrene,
10-(3,5-di-tert-butyl-4-hydroxybenzyl)-9,10-dihydroxy-9-oxa-10-phosphaphenanthrene-10-oxide,
10-decyloxy-9,10-dihydroxy-9-oxa-10-phosphaphenanthrene,
cyclic neopentanetetraylbis(2,4-di-tert-butylphenyl)phosphite,
cyclic neopentanetetraylbis(2,6-di-tert-butyl-4-methylphenyl)phosphite,
2,2-methylenebis(4,6-di-tert-butylphenyl)octyl phosphite,
2,4-bis-(n-octylthio)-6-(4-hydroxy-3,5-di-tert-butylanilino)-1,3,5-triazine,
Examples include phosphoric acid-based antioxidants such as octylated diphenylamine.

Examples of singlet oxygen quenchers include carotenes, dyes, amines, phenols, nickel complexes, and sulfides, such as 1,4-diazabicyclo[2,2,2]octane (DABCO), β-carotene, 1,3-cyclohexadiene, 2-diethylaminomethylfuran, 2-phenylaminomethylfuran, 9-diethylaminomethylanthracene, 5-diethylaminomethyl-6-phenyl-3,4-dihydroxypyran, nickel dimethyldithiocarbamate, nickel 3,5-di-tert-butyl-4-hydroxybenzyl-O-ethylphosphonate, and nickel 3,5-di-tert -butyl-4-hydroxybenzyl-O-butylphosphonate, nickel [2,2'-thiobis (4-tert-octylphenolate)] n-butylamine, nickel [2,2'-thiobis (4-tert-octylphenolate)] 2-ethylhexylamine, nickel bis [2,2'-thiobis (4-tert-octylphenolate)], nickel bis [2,2'-sulfone bis (4-octylphenolate)], nickel bis (2-hydroxy-5-methoxyphenyl-N-n-butylaldimine), nickel bis (dithiobenzyl), nickel bis (dithiobiacetyl), etc. can be mentioned as examples.

Examples of superoxide anion quenchers include complexes of superoxide dismutase with cobalt and nickel.

Examples of ozone quenchers include 4,4'-thiobis(6-tert-butyl-m-cresol), 2,4,6-tri-tert-butylphenol, 1,4-diazabicyclo[2,2,2]octane, N-phenyl-β-naphthylamine, α-tocopherol, 4,4'-methylene-bis(2,6-di-tert-butylphenol), P,P'-diaminodiphenylmethane, 2,2'-methylene-bis(6-tert-butyl-p-cresol), N,N'-diphenyl-p-phenylenediamine, N,N'-diphenylethylenediamine, and N-isopropyl-N'-phenyl-p-phenylenediamine.

The reversible thermochromic composition of the present invention is effective when used as is, but it can also be encapsulated in microcapsules to form a reversible thermochromic microencapsulated pigment (hereinafter sometimes referred to as a "microencapsulated pigment" or "pigment"), or dispersed in a thermoplastic resin or a thermosetting resin to form reversible thermochromic resin particles (hereinafter sometimes referred to as "resin particles").
The reversible thermochromic composition is preferably encapsulated in a microcapsule to form a reversible thermochromic microcapsule pigment, because the encapsulation in a microcapsule makes it possible to form a chemically and physically stable pigment, and the reversible thermochromic composition can be kept in the same composition under various conditions of use, and can exhibit the same effects.
Microencapsulation may be appropriately selected according to the application from the conventionally known isocyanate-based interfacial polymerization method, melamine-formaldehyde-based in situ polymerization method, liquid curing coating method, phase separation method from an aqueous solution, phase separation method from an organic solvent, melt dispersion cooling method, air suspension coating method, spray drying method, etc. Furthermore, a secondary resin film may be provided on the surface of the microcapsules according to the purpose to impart durability or to modify the surface properties for practical use.
The reversible thermochromic microcapsule pigment preferably has a mass ratio of inclusions to wall film of 7:1 to 1:1, and by having the mass ratio of inclusions to wall film within the above range, a decrease in color density and clarity during color development is prevented. More preferably, the mass ratio of inclusions to wall film is 6:1 to 1:1.

The average particle size of the reversible thermochromic microencapsulated pigment or resin particles is preferably in the range of 0.01 to 50 μm, more preferably 0.1 to 30 μm, and even more preferably 0.5 to 20 μm. If the average particle size of the microencapsulated pigment or resin particles exceeds 50 μm, the dispersion stability and processing suitability are lacking when blended into ink, paint, or resin. On the other hand, if the average particle size of the microencapsulated pigment or resin particles is less than 0.01 μm, it becomes difficult to exhibit high-concentration color development.
The average particle diameter was measured by determining the particle region using an image analysis type particle size distribution measurement software (manufactured by Mountec Corporation, product name: MacView), calculating the projected area equivalent circle diameter (Heywood diameter) from the area of the particle region, and measuring the average particle diameter of particles equivalent to a sphere of equal volume using this value.
When the particle size of all or most of the particles exceeds 0.2 μm, it is also possible to measure the average particle size of particles equivalent to an equal volume sphere by the Coulter method using a particle size distribution measuring device (product name: Multisizer 4e, manufactured by Beckman Coulter, Inc.).
Furthermore, the volumetric particle size and average particle size may be measured using a laser diffraction/scattering type particle size distribution measuring device (manufactured by HORIBA, Ltd., product name: LA-300) that has been calibrated based on values measured using the software or a measuring device using the Coulter method.

Reversible thermochromic compositions, reversible thermochromic microencapsulated pigments, or reversible thermochromic colorants such as resin particles can be dispersed in a vehicle containing water and/or an organic solvent and, if necessary, various additives to form an ink composition (hereinafter, sometimes referred to as "ink"), which can be used as a reversible thermochromic liquid composition such as printing ink used in screen printing, offset printing, process printing, gravure printing, coater printing, pad printing, etc.; paint used in brush painting, spray painting, electrostatic painting, electro-deposition painting, flow painting, roller painting, dip painting, etc.; inkjet ink; ultraviolet-curing ink; ink for writing instruments such as marking pens, ballpoint pens, fountain pens, and brush pens; ink for applicators; ink for stamps; paint; cosmetics; and coloring liquid for textiles.

The reversible thermochromic liquid composition may contain various additives.
Examples of the additives include resins, crosslinking agents, curing agents, drying agents, plasticizers, viscosity modifiers, dispersants, ultraviolet absorbers, antioxidants, light stabilizers, anti-settling agents, smoothing agents, gelling agents, defoaming agents, matting agents, penetrating agents, pH adjusters, foaming agents, coupling agents, moisturizing agents, antifungal agents, preservatives, and rust inhibitors.

Examples of the vehicle for use in the ink for a writing instrument include an oil-based vehicle containing an organic solvent, and an aqueous vehicle containing water and, if necessary, an organic solvent.
Examples of organic solvents include ethanol, propanol, butanol, glycerin, sorbitol, triethanolamine, diethanolamine, monoethanolamine, ethylene glycol, diethylene glycol, thiodiethylene glycol, polyethylene glycol, propylene glycol, butylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, sulfolane, 2-pyrrolidone, and N-methyl-2-pyrrolidone.

Examples of inks for writing instruments include shear-thinning inks that contain a shear-thinning agent in the vehicle, and cohesive inks that contain a polymer coagulant in the vehicle and suspend microencapsulated pigments in a loosely coagulated state.

An ink containing a shear thinning agent in the vehicle (shear thinning ink) can suppress aggregation and sedimentation of the microencapsulated pigment and can also suppress bleeding of handwriting, thereby forming good handwriting.
Furthermore, when a shear-thinning ink is contained in a ballpoint pen-shaped writing instrument, it is possible to prevent ink leakage from the gap between the ball and the tip when the writing instrument is not in use, and to prevent ink backflow when the writing tip is left facing upward (upright state).

Examples of shear-thinning agents include xanthan gum, welan gum, succinoglycan (average molecular weight: about 1 to 8 million), which is an organic acid-modified heteropolysaccharide whose constituent monosaccharides are glucose and galactose, alka gum, guar gum, locust bean gum and its derivatives, hydroxyethyl cellulose, alginic acid alkyl esters, polymers with a molecular weight of 100,000 to 150,000 that are mainly composed of alkyl esters of methacrylic acid, glucomannan, thickening polysaccharides with gelling ability extracted from seaweed such as agar and carrageenan, benzylidene sorbitol and benzylidene xylitol or derivatives thereof, cross-linked acrylic acid polymers, inorganic substances, etc. Examples include fine particles, polyglycerin fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyethylene glycol fatty acid esters, polyoxyethylene castor oil, polyoxyethylene lanolin, lanonine alcohol, beeswax derivatives, polyoxyethylene alkyl ethers, polyoxypropylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, fatty acid amides, and other nonionic surfactants with an HLB value of 8 to 12, salts of dialkyl or dialkenyl sulfosuccinic acid, mixtures of N-alkyl-2-pyrrolidone and anionic surfactants, and mixtures of polyvinyl alcohol and acrylic resins.

Ink containing a polymeric flocculant in the vehicle (flocculant ink) improves pigment dispersibility by forming loose aggregates of microencapsulated pigments via the polymeric flocculant, preventing the microencapsulated pigments from coming into contact with each other and flocculating.

Examples of the polymer flocculant include polyvinylpyrrolidone, polyethylene oxide, and water-soluble polysaccharides.
Examples of water-soluble polysaccharides include tragacanth gum, guar gum, pullulan, cyclodextrin, water-soluble cellulose derivatives, and the like.
Furthermore, examples of water-soluble cellulose derivatives include methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxyethyl methyl cellulose, and hydroxypropyl methyl cellulose.
Among the above polymer flocculants, hydroxyethyl cellulose is preferred because of its excellent dispersibility.

Specific examples of polymer flocculants include those manufactured by Sumitomo Seika Chemicals Co., Ltd. under the product names HEC A grade, S grade, and CF grade; those manufactured by Daicel Phi-Chem Co., Ltd. under the product names HEC Daicel SP type, SE type, and EE type; those manufactured by Dow Chemical Japan Co., Ltd. under the product names CELLOSIZE WP type, QP type, and EP type; and those manufactured by Sansho Co., Ltd. under the product name SANHEC.
The polymer flocculant is preferably blended in an amount of 0.1 to 1 mass %, more preferably 0.3 to 0.5 mass %, based on the total amount of the ink. By being in this range, the microencapsulated pigment forms loose aggregates, and the effect of improving the dispersibility of the pigment can be fully exerted.

Furthermore, the dispersibility of the microencapsulated pigment can be improved by blending a dispersant into the ink.
In addition, a polymer flocculant and a dispersant can be used in combination. When the two are used in combination, the dispersibility of the microencapsulated pigment can be improved, and the dispersibility of the loose aggregates of the microencapsulated pigment formed via the polymer flocculant can be further improved.

Examples of dispersants include synthetic resins such as polyvinylpyrrolidone, polyvinyl butyral, polyvinyl ether, styrene-maleic acid copolymer, ketone resin, hydroxyethyl cellulose and derivatives thereof, and styrene-acrylic acid copolymer, acrylic polymers, PO·EO adducts, and polyester amine oligomers.
Among the above dispersants, acrylic polymer dispersants are preferred because they have excellent dispersibility for the microencapsulated pigment, acrylic polymer dispersants having a carboxyl group are more preferred, and acrylic polymer dispersants having a comb structure and a carboxyl group on the side chain are even more preferred.
A particularly preferred dispersant is an acrylic polymer dispersant having a comb structure and multiple carboxyl groups on the side chains, and a specific example is Solsperse 43000, a product manufactured by Lubrizol Japan Co., Ltd.
The dispersant is preferably blended in an amount of 0.01 to 2% by mass, more preferably 0.1 to 1.5% by mass, based on the total amount of the ink. If the blending ratio of the dispersant exceeds 2% by mass, the microencapsulated pigment is likely to settle or float when subjected to external vibration, etc. On the other hand, if the blending ratio of the dispersant is less than 0.01% by mass, the effect of improving dispersibility is unlikely to be achieved.

In addition, by using a comb-shaped acrylic polymer dispersant having a carboxyl group on the side chain and an organic nitrogen-sulfur compound together with a polymer flocculant, the dispersibility of the loose aggregates of the microencapsulated pigment formed via the polymer flocculant can be improved.
The organic nitrogen sulfur compound further improves the dispersibility of the loose aggregates of the microencapsulated pigment, which are dispersed by the acrylic polymer dispersant with a comb-shaped structure having carboxyl groups on the side chains. Therefore, when the ink is placed in a writing instrument and used in practice, settling of the microencapsulated pigment due to vibration can be further suppressed.

Examples of the organic nitrogen-sulfur compound include compounds selected from thiazole-based compounds, isothiazole-based compounds, benzothiazole-based compounds, and benzisothiazole-based compounds. For example, one or more compounds selected from 2-(4-thiazoyl)-benzimidazole (TBZ), 2-(thiocyanatomethylthio)-1,3-benzothiazole (TCMTB), 2-methyl-4-isothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one, and the like can be exemplified.
Among the above organic nitrogen-sulfur compounds, one or more compounds selected from 2-(4-thiazoyl)-benzimidazole (TBZ), 2-methyl-4-isothiazolin-3-one, and 5-chloro-2-methyl-4-isothiazolin-3-one are preferred.
Specific examples of organic nitrogen-sulfur compounds include those manufactured by PermaChem Asia Co., Ltd., product names: Topside 88, 133, 170, 220, 288, 300, 400, 500, 600, 700Z, 800, and 950; and those manufactured by Hokko Sangyo Co., Ltd., product names: Hoxstar HP, Hoxstar E50A, Hoxside P200, 6500, 7400, Hoxside MC, 369, and Hoxside R-150.
The mass ratio of the acrylic polymer dispersant having a comb structure and having a carboxyl group in the side chain to the organic nitrogen sulfur compound is preferably 1:1 to 1:10, and more preferably 1:1 to 1:5. By being in this range, it is possible to fully exhibit the effect of dispersing the gentle aggregates of the microencapsulated pigment and suppressing sedimentation of the microencapsulated pigment due to vibration.

In addition, by blending a water-soluble resin into the ink, it is possible to impart adhesion and viscosity to the handwriting on the paper surface, and it is also possible to further improve the function of increasing the dispersibility of the microencapsulated pigment in the ink, which contains an acrylic polymer dispersant with a comb-shaped structure and carboxyl groups on the side chains, and an organic nitrogen-sulfur compound.

Examples of the water-soluble resin include alkyd resins, acrylic resins, styrene-maleic acid copolymers, cellulose derivatives, polyvinylpyrrolidone, polyvinyl alcohol, and dextrin.
Among the water-soluble resins, polyvinyl alcohol is preferred, and partially saponified polyvinyl alcohol with a saponification degree of 70 to 89 mol % is more preferred because the ink is highly soluble even in the acidic range.
The water-soluble resin is preferably blended in an amount of 0.3 to 3.0% by mass, more preferably 0.5 to 1.5% by mass, based on the total amount of the ink.

Furthermore, by adding a specific gravity adjuster to the ink, when the viscosity of the vehicle is low, it is possible to prevent the microencapsulated pigment from localizing by settling or floating in the ink when the ink is subjected to external stimuli such as vibration.

The specific gravity of the microencapsulated pigment depends on the particle size of the microencapsulated pigment, the components and their contents encapsulated in the microcapsules, the components and film thickness of the capsule wall membrane, the colored state of the microencapsulated pigment, and the temperature, but the specific gravity is preferably in the range of 1.05 to 1.20, more preferably 1.10 to 1.20, and even more preferably 1.12 to 1.15 when the microencapsulated pigment is in a completely colored state and water is used as the reference substance in an environment of 20° C. Furthermore, microencapsulated pigments having a large hysteresis width (ΔH) often use a component (c) having two or more aromatic rings in the molecule, and have a large specific gravity as described above, but in an ink containing a specific gravity adjuster, even if the viscosity of the vehicle is low, the microencapsulated pigment is prevented from settling or floating in the ink when subjected to external influences such as vibration during transportation, etc.
The specific gravity of the microcapsulated pigment can be measured by the following method.

(Method for measuring specific gravity of microcapsule pigment)
1. 30 ml of an aqueous glycerin solution and 1 g of a microcapsule pigment in a fully colored state are placed in a screw cap bottle and mixed to obtain a microcapsule pigment dispersion.
2. 30 ml of the microcapsule pigment dispersion is adjusted to 20° C. and centrifuged at 1000 rpm for 30 seconds. A cooling tabletop centrifuge (manufactured by Kokusan Co., Ltd., product name: H103N) can be used as the centrifuge.
3. Observe the microcapsule pigment dispersion.
If most of the microencapsulated pigment has settled to the bottom of the beaker, repeat steps 1 and 2 using an aqueous solution with a higher glycerin concentration than the aqueous glycerin solution used at this time, and observe the state of the dispersion.
If it is confirmed that most of the microencapsulated pigment is floating on the liquid surface, repeat steps 1 and 2 using an aqueous solution with a lower glycerin concentration than the aqueous glycerin solution used at this time, and observe the state of the dispersion.
The above series of operations is repeated until it is visually confirmed that the majority of the microencapsulated pigment is not floating on the liquid surface or settling, but that the glycerin aqueous solution is uniformly colored except for the liquid surface and the bottom of the screw tube bottle. The specific gravity of the glycerin aqueous solution when this state is observed is measured and used as the specific gravity of the microencapsulated pigment. The specific gravity of the glycerin aqueous solution can be measured by the hydrometer method described in JIS K0061, Section 7.1, using an aqueous solution adjusted to 20°C.

The settling and floating stability of the pigment is at its highest when the difference in specific gravity between the vehicle and the pigment is minimal, and the specific gravity adjuster brings the specific gravity of the vehicle closer to that of the microencapsulated pigment. The specific gravity of the vehicle depends on the specific gravity of the water-soluble substance dissolved in the vehicle and the amount added, so adding and dissolving a larger specific gravity adjuster in the vehicle can increase the specific gravity of the vehicle.

Specific gravity adjusters include those that dissolve in the vehicle and adjust the specific gravity of the vehicle to be closer to that of the microcapsule pigment, such as oxygen acids and salts of Group 6 elements with atomic weights in the range of 90 to 185.

The oxygen acid and its salt are selected from the group consisting of oxygen acids of transition metal elements and their salts, and the oxygen acid ions are said to form tetrahedrons or octahedrons in which oxygen atoms are usually coordinated to metal atoms or the like in a 4- or 6-position.
The tetrahedral or octahedral units may be a single unit, or may be a polyacid having a structure in which the tetrahedral or octahedral units are bonded via edges or vertices, and a polyacid salt thereof. A polyacid is a polyacid formed by condensation of oxyacids of metal elements, and a polyacid composed of only one type of metal and in which all the condensed anions are of the same type is called an isopolyacid, and a polyacid in which two or more types of anions are condensed is called a heteropolyacid. The respective salts are called isopolyacid salts and heteropolyacid salts. The above polyacids include isopolyacids, heteropolyacids, etc., and the above polyacid salts include isopolyacids, heteropolyacids, etc.

Examples of the specific gravity adjuster include a single oxyacid and its salt, an isopolyacid and its salt, and a heteropolyacid and its salt.
Examples of the single oxyacid include molybdic acid and tungstic acid, and examples of the salt of the single oxyacid include sodium molybdate, potassium molybdate, ammonium molybdate, sodium tungstate, potassium tungstate, ammonium tungstate, lithium tungstate, and magnesium tungstate.
Examples of isopolyacids include metamolybdic acid, paramolybdic acid, metatungstic acid, paratungstic acid, isotungstic acid, and the like. Further, examples of isopolyacid salts include sodium metamolybdate, potassium metamolybdate, ammonium metamolybdate, sodium paramolybdate, potassium paramolybdate, ammonium paramolybdate, sodium metatungstate, potassium metatungstate, ammonium metatungstate, barium metatungstate, sodium paratungstate, sodium isotungstate, and the like.
Examples of heteropolyacids include molybdophosphoric acid, molybdosilicic acid, tungstophosphoric acid, and tungstosilicic acid, and examples of heteropolyacid salts include sodium molybdophosphate, sodium molybdosilicate, sodium tungstophosphate, and sodium tungstosilicate.
The oxygen acids and salts thereof may be used alone or in combination of two or more kinds.

Among the specific gravity adjusters, metatungstic acid, paratungstic acid, sodium metatungstate, potassium metatungstate, ammonium metatungstate, barium metatungstate, sodium paratungstate, sodium isotungstate, tungstophosphoric acid, tungstosilicic acid, sodium tungstophosphate, and sodium tungstosilicate are preferred, and sodium isotungstate, sodium metatungstate, and sodium paratungstate are more preferred.
The sodium isotungstate, sodium metatungstate, and sodium paratungstate are not only highly safe but also have a high specific gravity themselves, so that it is easy to adjust the high specific gravity liquid according to the amount added, and are therefore preferable.

The specific gravity adjuster is preferably blended in an amount of 2 to 20% by mass, more preferably 5 to 15% by mass, based on the total amount of the ink. If the blending ratio of the specific gravity adjuster exceeds 20% by mass, the microcapsule pigment tends to aggregate. On the other hand, if the blending ratio of the specific gravity adjuster is less than 2% by mass, the effect of adjusting the specific gravity of the vehicle becomes poor.
The mass ratio of the microencapsulated pigment to the specific gravity adjusting agent is preferably 0.05 to 4.0, more preferably 0.075 to 2.0, and even more preferably 0.1 to 1.5.

When the vehicle for the writing instrument is an aqueous vehicle, the vehicle contains at least water, and the amount of water is preferably 30 to 80% by weight, more preferably 40 to 70% by weight, based on the total amount of the ink.

Furthermore, by blending a water-soluble organic solvent into the ink, evaporation of water from the ink can be suppressed, fluctuations in the specific gravity of the vehicle can be prevented, and good dispersion stability of the microencapsulated pigment can be maintained, while the structure of the polymer flocculant or the loose aggregates formed by the polymer flocculant and the dispersant can be stabilized.
Examples of the water-soluble organic solvent include ethanol, propanol, butanol, glycerin, sorbitol, triethanolamine, diethanolamine, monoethanolamine, ethylene glycol, diethylene glycol, thioethylene glycol, polyethylene glycol, propylene glycol, butylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, sulfolane, 2-pyrrolidone, and N-methyl-2-pyrrolidone.
When the hysteresis width (ΔH) of the microencapsulated pigment to be incorporated in the ink is large, the specific gravity of the microencapsulated pigment is greater than 1. Since using a water-soluble organic solvent having a specific gravity greater than that of water makes it easier to adjust the specific gravity of the vehicle, it is preferable to use glycerin or the like having a specific gravity of more than 1.1 as the water-soluble organic solvent.

The water-soluble organic solvent is preferably blended in an amount of 1 to 40% by mass, more preferably 5 to 30% by mass, and even more preferably 10 to 25% by mass, based on the total amount of ink. If the blending ratio of the water-soluble organic solvent exceeds 40% by mass, the dissolution stability of the specific gravity adjuster is likely to decrease. On the other hand, if the blending ratio of the water-soluble organic solvent is less than 1% by mass, the effect of suppressing water evaporation becomes poor.

When the writing ink is used in a ballpoint pen, it is preferable to add a lubricant such as a higher fatty acid such as oleic acid, a nonionic surfactant with a long-chain alkyl group, polyether-modified silicone oil, a thiophosphite triester such as thiophosphite tri(alkoxycarbonylmethyl ester) or thiophosphite tri(alkoxycarbonylethyl ester), a phosphate monoester of polyoxyethylene alkyl ether or polyoxyethylene alkylaryl ether, a phosphate diester of polyoxyethylene alkyl ether or polyoxyethylene alkylaryl ether, or a metal salt, ammonium salt, amine salt, or alkanolamine salt thereof to the ink to prevent wear of the ball seat.

In addition, various additives such as a pH adjuster, a rust inhibitor, a preservative, or an antifungal agent may be added as necessary.
Examples of the pH adjuster include inorganic salts such as sodium carbonate, sodium phosphate, and sodium acetate, and organic basic compounds such as water-soluble amine compounds.
Examples of the rust inhibitor include benzotriazole, tolyltriazole, dicyclohexylammonium nitrite, diisopropylammonium nitrite, and saponin.
Examples of the preservative or antifungal agent include carbolic acid, sodium salt of 1,2-benzthiazolin-3-one, sodium benzoate, sodium dehydroacetate, potassium sorbate, propyl paraoxybenzoate, and 2,3,5,6-tetrachloro-4-(methylsulfonyl)pyridine.
Other additives include urea, nonionic surfactants, reduced or non-reduced starch hydrolysates, oligosaccharides such as trehalose, wetting agents such as sucrose, cyclodextrin, glucose, dextrin, sorbitol, mannitol, and sodium pyrophosphate, antifoaming agents, dispersants, fluorine-based surfactants that improve the penetration of ink, and nonionic surfactants.

The ink contains a reversible thermochromic microencapsulated pigment in an amount of preferably 5 to 40% by mass, more preferably 10 to 40% by mass, and even more preferably 10 to 30% by mass, based on the total amount of the ink. By containing the microencapsulated pigment in the above range, the desired color density can be obtained and a decrease in ink outflow can be prevented.

The ink composition according to the present invention can be produced by any conventionally known method. Specifically, the ink composition can be produced by blending the required amounts of the above-mentioned components and mixing them with various stirrers such as a propeller stirrer, homodisper, or homomixer, or various dispersing machines such as a bead mill.

When the writing ink according to the present invention is used in a ballpoint pen, the viscosity is preferably in the range of 1 to 2000 mPa·s, more preferably 3 to 1500 mPa·s, and even more preferably 500 to 1000 mPa·s, since the ink can suppress sedimentation or aggregation of the microcapsule pigment when measured at a rotation speed of 3.84 sec ^{-1 in} an environment of 20°C. Furthermore, the viscosity is preferably in the range of 1 to 200 mPa·s, more preferably 10 to 100 mPa·s, and even more preferably 20 to 50 mPa·s, since the ink can improve the ink dischargeability from the pen tip of the ballpoint pen when measured at a rotation speed of 384 sec-1 in an environment of 20°C.
By having the viscosity within the above range, it is possible to maintain the dispersion stability of the microencapsulated pigment and the free flowability of the ink within the mechanism of the ballpoint pen at a high level.
The viscosity can be measured using a digital viscometer (Brookfield, product name: DV-II, cone-type rotor (CPE-42)) by placing the ink in an environment of 20°C and at a shear rate of 3.84 sec ^-1 (1 rpm) or 384 sec ^-1 (100 rpm).

When the writing instrument ink according to the present invention is used in a ballpoint pen, the surface tension is preferably in the range of 20 to 50 mN/m, more preferably 25 to 45 mN/m, in an environment of 20° C. By having a surface tension in the above range, it is easy to suppress bleeding of written lines and strike-through onto the paper surface, and the wettability of the ink to the paper surface can be improved.
The surface tension can be measured by a surface tension meter (manufactured by Kyowa Interface Science Co., Ltd., product name: DY-300) by placing the ink in an environment of 20° C. and using a platinum plate according to the vertical plate method.

When the writing instrument ink according to the present invention is used in a ballpoint pen, the pH is preferably in the range of 3 to 10, more preferably 4 to 9. By having the pH in this range, aggregation or precipitation of the microencapsulated pigment contained in the ink in the low temperature range can be suppressed.
The pH can be measured by placing the ink in an environment of 20° C. using a pH meter (manufactured by DKK-TOA Corporation, product name: IM-40S type).

When the ink for a writing instrument according to the present invention is used in a marking pen, the viscosity is preferably in the range of 3 to 25 mPa·s, more preferably 4 to 20 mPa·s, and even more preferably 5 to 15 mPa·s when measured under conditions of a rotation speed of 6 rpm in an environment of 20° C. Furthermore, when measured under conditions of a rotation speed of 12 rpm, the viscosity is preferably in the range of 2 to 20 mPa·s, more preferably 3 to 15 mPa·s, and even more preferably 4 to 15 mPa·s. When measured under conditions of a rotation speed of 30 rpm, the viscosity is preferably in the range of 1 to 20 mPa·s, more preferably 2 to 15 mPa·s, and even more preferably 3 to 10 mPa·s. By having the viscosity in the above range, the fluidity of the ink and the dispersion stability of the microencapsulated pigment can be improved.
The viscosity can be measured by placing the ink in an environment of 20° C. using a BL type rotational viscometer (manufactured by Toki Sangyo Co., Ltd., product name: TVB-M type viscometer, B type rotor).

When the ink for a writing instrument according to the present invention is used in a marking pen, the surface tension thereof is preferably in the range of 25 to 50 mN/m, more preferably 25 to 45 mN, and even more preferably 35 to 45 mN/m in an environment of 20° C. By having a surface tension within the above range, it is easy to suppress bleeding of written lines and strike-through onto the paper surface, and the wettability of the ink to the paper surface can be improved.
The surface tension can be measured by a surface tension meter (manufactured by Kyowa Interface Science Co., Ltd., product name: DY-300) by placing the ink in an environment of 20° C. and using a glass plate according to the vertical plate method.

When the writing ink according to the present invention is used in a marking pen, its pH is preferably in the range of 3 to 8, more preferably 4 to 7, and even more preferably 5 to 6. By having a pH in the above range, aggregation or precipitation of the microencapsulated pigment contained in the ink in a low temperature range can be suppressed.
The pH can be measured by placing the ink in an environment of 20° C. using a pH meter (manufactured by DKK-TOA Corporation, product name: IM-40S type).

A writing instrument containing the writing instrument ink of the present invention preferably contains 5 to 40% by mass of reversible thermochromic microencapsulated pigment in the total amount of the writing instrument ink, and consumes 60 to 280 mg of ink when writing 50 m on writing paper A conforming to old JIS P3201 at 20°C, and the value C obtained by dividing the density value of the handwriting in a colored state by the density value of the handwriting in a decolorized state is 20 or more.

If the blending ratio of microcapsule pigment exceeds 40% by mass, the ink flowability is likely to decrease, and the amount of microcapsule pigment accumulated on the paper surface becomes excessive, requiring more heat to erase or discolor the colored handwriting, which can be a strain on the hands when rubbing the handwriting to erase or discolor it. On the other hand, if the blending ratio of microcapsule pigment is less than 5% by mass, it becomes difficult to obtain the desired color density.

A writing instrument such as a ballpoint pen or a marking pen that contains the writing instrument ink will now be described.
When filling a ballpoint pen, the structure and shape of the ballpoint pen itself are not particularly limited, and an example is a ballpoint pen having an ink reservoir tube filled with shear-thinning ink inside a barrel, the ink reservoir tube communicating with a ballpoint pen tip having a ball attached to the tip, and further having a liquid plug in close contact with the end face of the ink to prevent backflow.
Examples of ballpoint pen tips include tips in which a ball is held in a ball-holding portion formed by deforming the area near the tip of a metal pipe by pressing inward from the outer surface, tips in which a ball is held in a ball-holding portion formed by cutting a metal material with a drill or the like, tips in which a resin ball receiving seat is provided inside a metal or plastic tip, and tips in which the ball held in the tip is urged forward by a spring body.
The material of the ballpoint pen tip and ball is not particularly limited, and examples thereof include cemented carbide (super hard), stainless steel, ruby, ceramic, resin, rubber, and the like.
The diameter of the ball is preferably about 0.3 to 2.0 mm, more preferably about 0.3 to 1.5 mm, and even more preferably about 0.3 to 1.0 mm.
Generally, a ballpoint pen with a small diameter ball consumes less ink and tends to have low writing density, and a ballpoint pen containing a writing instrument ink containing a reversible thermochromic microcapsule pigment tends to have difficulty in obtaining high writing density. Furthermore, since the amount of ink on the ball surface is small, the ball surface dries (dries up), which tends to cause writing defects such as smudges. In particular, when the blending ratio of the microcapsule pigment in the ink is increased to increase the solid content in the ink in order to improve the writing density, the dry-up resistance tends to decrease. However, when the writing instrument ink of the present invention is used in a ballpoint pen with a ball having a diameter of 0.3 to 0.5 mm, it is possible to increase the writing density without increasing the solid content of the pigment, improve the writing density without impairing the dry-up resistance, and provide a writing instrument with excellent contrast between the colored state and the decolored state.
In general, ballpoint pens with large diameter balls consume a large amount of ink and tend to produce high handwriting density, and ballpoint pens containing writing instrument inks containing reversible thermochromic microcapsule pigments can produce high handwriting density, but tend to leave a visible residual color when the handwriting is erased. However, when the writing instrument ink of the present invention is used in a ballpoint pen with a ball having a diameter of 0.5 to 1.0 mm, it is possible to make the residual color in the erased state of the handwriting less visible, resulting in a writing instrument with excellent contrast between the colored state and the erased state.

The ink reservoir tube may be a molded body made of a thermoplastic resin such as polyethylene, polypropylene, polyethylene terephthalate, or nylon, or a tubular body made of metal.
The ink reservoir may be connected to the tip directly or through a connecting member.
In addition, the ink holding tube may be in the form of a refill, with the refill housed in a barrel made of resin, metal, etc., or the barrel itself with a tip attached to the end may serve as the ink container, with ink being filled directly into the barrel.

Furthermore, when ink is stored in a retractable ballpoint pen, the structure and shape of the retractable ballpoint pen are not particularly limited, and any structure can be used as long as the writing tip provided on the ballpoint pen refill is stored within the barrel while being exposed to the outside air, and the writing tip protrudes from the barrel opening upon activation of the retractable mechanism.
Examples of the retraction mechanism include: (1) a side-slide type retraction mechanism in which an operating part (clip) movable in the front-rear direction protrudes radially outward from the rear side wall of the barrel, and the operating part is slid forward to cause the writing tip to appear and disappear from the front end opening of the barrel; (2) a rear-end knock type retraction mechanism in which an operating part provided at the rear end of the barrel is pressed forward to cause the writing tip to appear and disappear from the front end opening of the barrel; (3) a side-knock type retraction mechanism in which an operating part protruding from the outer surface of the barrel side wall is pressed radially inward to cause the writing tip to appear and disappear from the front end opening of the barrel; and (4) a rotating type retraction mechanism in which an operating part at the rear of the barrel is rotated to cause the writing tip to appear and disappear from the front end opening of the barrel.
The retractable ballpoint pen may be a composite type retractable ballpoint pen that contains a plurality of ballpoint pen refills in a barrel and causes the writing tip of one of the ballpoint pen refills to protrude and retract from the front end opening of the barrel by operating a retractable mechanism.

The rear end of the ink filled in the ink reservoir is filled with an ink backflow preventer.
The ink backflow preventive composition comprises a non-volatile liquid or a hardly volatile liquid, examples of which include petrolatum, spindle oil, castor oil, olive oil, refined mineral oil, liquid paraffin, polybutene, α-olefin, α-olefin oligomer or cooligomer, dimethyl silicone oil, methylphenyl silicone oil, amino-modified silicone oil, polyether-modified silicone oil, fatty acid-modified silicone oil, and the like.
The ink backflow preventive composition may be used alone or in combination of two or more kinds.

It is preferable to thicken the non-volatile liquid and/or the low-volatility liquid to a suitable viscosity by adding a thickener.
Examples of thickeners include clay-based thickeners such as silica whose surface has been hydrophobically treated, fine particle silica whose surface has been methylated, aluminum silicate, swellable mica, and bentonite and montmorillonite that have been hydrophobically treated; fatty acid metal soaps such as magnesium stearate, calcium stearate, aluminum stearate, and zinc stearate; tribenzylidene sorbitol, fatty acid amides, amide-modified polyethylene wax, hydrogenated castor oil, dextrin-based compounds such as fatty acid dextrins, and cellulose-based compounds.
Furthermore, the liquid ink backflow preventive composition and a solid ink backflow preventive composition may be used in combination.

When filling a marking pen, the structure and shape of the marking pen itself are not particularly limited, and examples include a marking pen in which an ink occlusion body made of a fiber bundle is built into the barrel, and a marking pen tip made of a fiber processed body with capillary gaps is attached to the barrel directly or via an intermediate member, and the ink occlusion body and tip are connected to the ink occlusion body, and the ink is impregnated with cohesive ink, and a marking pen in which the tip and an ink reservoir are arranged via a valve that opens when the tip is pressed, and the ink is directly contained in the ink reservoir.

Examples of marking pen tips include conventional porous materials with interconnected pores, such as resin-processed fibers, fused heat-melting fibers, and felt, with a porosity selected from the range of approximately 30 to 70%, and one end of the tip is processed into a bullet shape, rectangular shape, chisel shape, or other shape suited to the purpose for which it is used.

The ink occlusion body is made by bundling crimped fibers in the longitudinal direction, and is placed inside a plastic cylinder or a covering such as a film, with the porosity adjusted to a range of approximately 40 to 90%.

The valve body can be of the conventional general-purpose pumping type, but it is preferable to use one with a spring pressure that can be pressed and released by the pressure of the pen.

Furthermore, the shape of the ballpoint pen or marking pen is not limited to those described above, but may be a composite writing instrument (double-headed, tip-operating, etc.) equipped with tips of different shapes or with pen tips that dispense ink of different colors.

The handwriting obtained by writing on a surface to be written on using a writing instrument containing the ink for writing instruments can be discolored by rubbing with a finger or by using a heating or cooling tool.
Examples of the heating tool include an electrically-heated color-changing tool equipped with a resistance heating element such as a PTC element, a heat-changing tool filled with a medium such as hot water, a heat-changing tool using steam or laser light, application of a hair dryer, etc. A friction member is preferably used because it can change color by a simple method.
Examples of cooling devices include electrochemically-induced color-changing devices using a Peltier element, color-changing devices filled with a refrigerant such as cold water or ice chips, cooling agents, refrigerators, freezers, and the like.

The friction member is preferably an elastic body such as an elastomer or plastic foam, which has a high elastic feel and can generate appropriate friction and heat during rubbing.
Although a general eraser for erasing pencil marks may be used to rub the marks, the rub produces eraser dust during the rub, and therefore the above-mentioned friction member, which produces almost no eraser dust, is preferably used.
Examples of the material for the friction member include silicone resin, SEBS resin (styrene-ethylene-butadiene-styrene block copolymer), and polyester resin.

In addition, a writing instrument set can be obtained by combining a writing instrument with a friction member (friction body) of any shape that is separate from the writing instrument, and by providing the friction member on the writing instrument, the writing instrument can be made to have excellent portability.
In the case of a writing instrument with a cap, the location where the friction member is provided is not particularly limited, and for example, the cap itself may be formed from a friction member, the barrel itself may be formed from a friction member, or if a clip is provided, the clip itself may be formed from a friction member, or the friction member may be provided at the tip (top) of the cap or the rear end of the barrel (the part where the writing tip is not provided).
In the case of a retractable writing instrument, the location where the friction member is provided is not particularly limited, and for example, the barrel itself may be formed from a friction member, or if a clip is provided, the clip itself may be formed from a friction member, or the friction member may be provided near the opening of the barrel, at the rear end of the barrel (the portion where the writing tip is not provided), or at the knock portion.

The ink can also be used as a stamp ink.
Water is used as the medium for the ink for stamping, but a water-soluble organic solvent can also be used if necessary.
Examples of the water-soluble organic solvent include glycols such as glycerin, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, 1,3-butylene glycol, and ethylene glycol monomethyl ether, as well as lower alkyl ethers thereof, 2-pyrrolidone, N-vinylpyrrolidone, and urea.
When a reversible thermochromic microencapsulated pigment is used in the ink for stamps, glycerin and propylene glycol are preferred among the above water-soluble organic solvents.

The water-soluble organic solvent is preferably blended in an amount of 30 to 60% by mass, more preferably 30 to 55% by mass, and even more preferably 40 to 50% by mass, based on the total amount of the ink. By having the blending ratio of the water-soluble organic solvent within the above range, the ink will not dry out or absorb moisture, making it easier to obtain a clear printed image.
If the blending ratio of the water-soluble organic solvent exceeds 60% by mass, the hygroscopicity is likely to be high, and the printed image may bleed or become mottled, making it difficult to obtain a clear printed image. On the other hand, if the blending ratio of the water-soluble organic solvent is less than 30% by mass, the printed surface may dry out, causing the printed image to fade, making it difficult to obtain a clear printed image.

As the medium, an organic solvent may be used in addition to the water-soluble organic solvent.
Examples of the organic solvent include castor oil fatty acid alkyl esters, cellosolve-based solvents such as methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, and ethyl cellosolve acetate, ethylene glycol acetate, ethylene glycol diethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol dimethyl ether, diethylene glycol monoethyl ether acetate, propylene glycol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, and propylene glycol. Alkylene glycol solvents such as monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, dipropylene glycol monomethyl ether acetate, and tripropylene glycol monomethyl ether; ethyl formate, amyl formate, ethyl acetate, ethyl acetoacetate, propyl acetate, butyl acetate, 3-methyl-3-methoxybutyl acetate, amyl acetate, methyl-3-methoxypropionate, ethyl-3-methoxypropionate, ethyl-3-ethoxypropionate, Ester-based solvents such as butyl 3-methoxypropionate, propyl 3-methoxypropionate, butyl 3-methoxypropionate, methyl lactate, ethyl lactate, ethyl 2-hydroxybutyrate, butyl butyrate, butyl stearate, ethyl caprate, diethyl oxalate, ethyl pyruvate, and ethyl benzoate; hydrocarbon-based solvents such as n-pentane, n-hexane, n-octane, n-dodecane, diisobutylene, dipentene, hexene, methylcyclohexene, bicyclohexyl, and mineral spirits; halogenated hydrocarbon-based solvents such as amyl chloride and butyl chloride; alcohol-based solvents such as 3-methoxy-3-methylbutanol and 3-methoxy-3-methylpentanol; diethyl ether, dipropyl ether, and the like. Examples of the solvent include ether-based solvents such as ether, ethyl isobutyl ether, dibutyl ether, diisopropyl ether, diamyl ether, and dihexyl ether; ketone-based solvents such as acetone, methyl ethyl ketone, methyl isopropyl ketone, methyl butyl ketone, methyl isobutyl ketone, methyl isoamyl ketone, ethyl amyl ketone, methyl hexyl ketone, methyl nonyl ketone, diisopropyl ketone, diisobutyl ketone, methoxymethyl pentanone, and cyclohexanone; propionic acid-based solvents such as 3-methoxypropionic acid and 3-ethoxypropionic acid; highly polar solvents such as dimethylformamide, dimethylacetamide, dimethylsulfoxide, N-methylpyrrolidone, and benzonitrile; and mixed solvents thereof.

Furthermore, a thickener can be added to the ink.
Examples of thickening agents include xanthan gum, welan gum, succinoglycan (average molecular weight: about 1 to 8 million), which is an organic acid-modified heteropolysaccharide whose constituent monosaccharides are glucose and galactose, guar gum, locust bean gum and derivatives thereof, hydroxyethyl cellulose, alginic acid alkyl esters, polymers having a molecular weight of 100,000 to 150,000 and mainly composed of alkyl esters of methacrylic acid, glycomannan, thickening polysaccharides having gelling ability extracted from seaweed such as agar and carrageenin, benzylidene sorbitol and benzylidene xylitol, or polysaccharides having the same or similar properties. Examples of such surfactants include derivatives thereof, crosslinkable acrylic acid polymers, inorganic fine particles, polyglycerol fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyethylene glycol fatty acid esters, polyoxyethylene castor oil, polyoxyethylene lanolin/lanolin alcohol/beeswax derivatives, polyoxyethylene alkyl ethers/polyoxypropylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, fatty acid amides and other nonionic surfactants having an HLB value of 8 to 12, and salts of dialkyl or dialkenyl sulfosuccinic acid.
Among the above thickeners, alkali-soluble acrylic emulsions are preferred.
When an alkali-soluble acrylic emulsion is used as a thickener, the pH of the ink is adjusted to preferably 6-11, more preferably 7-11, and even more preferably 7-10.

Furthermore, by adding a binder resin to the ink, the adhesion of the printed image can be improved and the viscosity of the ink can be adjusted.
Examples of the binder resin include a resin emulsion, an alkali-soluble resin, and a water-soluble resin.
Examples of the resin emulsion include aqueous dispersions of polyacrylic acid esters, styrene-acrylic acid copolymers, polyvinyl acetate, ethylene-vinyl acetate copolymers, ethylene-vinyl chloride copolymers, methacrylic acid-maleic acid copolymers, ethylene-methacrylic acid copolymers, α-olefin-maleic acid copolymers, polyesters, polyurethanes, and the like.
Examples of the alkali-soluble resin include styrene-maleic acid copolymer, ethylene-maleic acid copolymer, and styrene-acrylic acid copolymer.
Examples of the water-soluble resin include polyvinyl alcohol and polyvinyl butyral.
The resin emulsions may be used alone or in combination of two or more kinds.

In addition, various additives such as a pH adjuster, a preservative, or an antifungal agent may be added as necessary.
Examples of pH adjusters include inorganic salts such as ammonia, sodium carbonate, sodium phosphate, sodium hydroxide, and sodium acetate, and organic basic compounds such as water-soluble amine compounds such as triethanolamine and diethanolamine.
Examples of the preservative or antifungal agent include carbolic acid, sodium salt of 1,2-benzisothiazolin-3-one, sodium benzoate, sodium dehydroacetate, potassium sorbate, propyl paraoxybenzoate, and 2,3,5,6-tetrachloro-4-(methylsulfonyl)pyridine.
Other additives include fluorine-based surfactants, which improve the permeability of the solvent, nonionic surfactants, anionic surfactants, cationic surfactants, dimethylpolysiloxane, and the like.

If necessary, resins such as acrylic resins, styrene-maleic acid copolymers, cellulose derivatives, polyvinylpyrrolidone, polyvinyl alcohol, and dextrin can be added to impart adhesion and viscosity to the paper surface.

It is also possible to add rust inhibitors such as benzotriazole, tolyltriazole, dicyclohexylammonium nitrite, diisopropylammonium nitrite, and saponin, urea, nonionic surfactants, reduced or non-reduced starch hydrolysates and oligosaccharides such as trehalose, wetting agents such as sucrose, cyclodextrin, glucose, dextrin, sorbitol, mannitol, and sodium pyrophosphate, antifoaming agents, dispersants, fluorine-based surfactants that improve the permeability of the ink, and nonionic surfactants.

The ink contains a reversible thermochromic microencapsulated pigment in an amount of preferably 10 to 40% by mass, more preferably 10 to 35% by mass, and even more preferably 10 to 30% by mass, based on the total amount of the ink. If the amount of the microencapsulated pigment exceeds 40% by mass, the dispersion stability of the microencapsulated pigment in the ink tends to decrease. On the other hand, if the amount of the microencapsulated pigment is less than 10% by mass, the color density tends to decrease.

The ink for stamps can be used as ink for stamp pads and ink for stamps provided with a printing material having continuous pores.
For example, a stamp pad can be impregnated with ink to obtain a stamp pad that supplies ink to the printing surface of a stamp that is brought into contact with the stamp pad, or a stamp can be obtained by impregnating ink into the printing material of a stamp having continuous pores.

A stamp equipped with a printing material with continuous pores is made by impregnating ink into the printing material, a rubber-like elastic body with continuous pores, and when this is pressed against a surface to be imprinted, the ink moves to the surface through the openings of the continuous pores, transferring the surface shape of the stamp. Areas where transfer is not desired are made into recesses, or the openings are closed to prevent the ink from adhering to the surface to be imprinted.
The surface shape of the stamp may include a date, a symbol, or text such as "Confidential,""Confidential,""Completed," or "Received."

The stamp material having continuous pores is placed in the stamp base material so that its printing surface is exposed, and the exposed surface is preferably provided with a cap to prevent the ink from drying out when not in use or to prevent contamination due to accidental contact.
In addition, an ink reservoir for supplying ink to the printing material may be provided at the rear of the printing material having continuous pores, thereby increasing the number of times the printing can be performed.

In addition to pre-impregnating the printing material with ink and attaching it to the stamp, the printing material of the stamp to which the printing material is attached can also be impregnated with ink.
When the printing material of the stamp to which the printing material is attached is impregnated with ink, the printing material may be impregnated with ink from the front surface or from the rear surface of the printing material.
Similarly, in the case of a stamp having an ink reservoir, the ink reservoir may be filled with ink beforehand and attached to the stamp, or the ink reservoir of a stamp provided with a printing material and an ink reservoir may be filled with ink.

The stamp is capable of forming an image on various surfaces. Furthermore, the image formed by the stamp ink can be discolored by rubbing it with a finger or by applying the heating or cooling tool described above. The heating tool is preferably the friction member described above, since it can be discolored in a simple manner.

A stamp set can also be obtained by combining a stamp with a friction member (friction body) of any shape that is separate from the stamp, but by providing the aforementioned friction member on the stamp, it can be made highly portable.

When applying or printing the reversible thermochromic liquid composition, the material of the support is not particularly limited and all materials are effective, for example, paper, synthetic paper, fiber, cloth, synthetic leather, leather, plastic, glass, ceramic material, metal, wood, stone, etc.
The shape of the support is not limited to a flat shape, but may be uneven.
A reversible thermochromic layer containing a reversible thermochromic colorant such as a reversible thermochromic composition, a reversible thermochromic microcapsule pigment or resin particles can be provided on a support to obtain a reversible thermochromic laminate (reversible thermochromic printed material).
In the case of a support on which a non-thermochromic colored layer (non-thermochromic image) has been formed in advance, the colored layer or image can be made to disappear or appear by the reversible thermochromic layer due to a change in temperature, thereby making it possible to further diversify the manner of change.

Furthermore, a reversible thermochromic composition, a reversible thermochromic colorant such as a reversible thermochromic composition, a reversible thermochromic microcapsule pigment, or a resin particle can be melt-blended with an excipient and molded to form a reversible thermochromic solid molded article for application, which can be used as a solid writing material or a solid cosmetic material.
Examples of solid writing materials include crayons, pencil leads, mechanical pencil leads, solid gel markers, and the like.
Examples of solid cosmetics include foundation, eyeliner, eyebrow cream, eyeshadow, lipstick, etc.

Examples of excipients used in solid writing materials include waxes, gelling agents, clays, and the like.
The wax is not particularly limited as long as it is a conventionally known wax, and examples thereof include carnauba wax, Japan wax, beeswax, microcrystalline wax, montan wax, candelilla wax, sucrose fatty acid ester, dextrin fatty acid ester, polyolefin wax, styrene-modified polyolefin wax, and paraffin wax.
The gelling agent is not particularly limited as long as it is a conventionally known agent, and examples thereof include 12-hydroxystearic acid, dibenzylidene sorbitols, tribenzylidene sorbitols, amino acid oils, and alkali metal salts of higher fatty acids.
Examples of clay minerals include kaolin, bentonite, and montmorillonite.

Among the above-mentioned excipients, it is preferable to contain at least one of polyolefin wax, sucrose fatty acid ester, and dextrin fatty acid ester, since these are likely to improve the writing density.
Examples of polyolefin waxes include waxes such as polyethylene, polypropylene, polybutylene, α-olefin polymers, ethylene-propylene copolymers, and ethylene-butene copolymers.

Furthermore, among the above polyolefin waxes, those having a softening point in the range of 100 to 130° C. and a needle penetration of 10 or less are preferred because they are easy to write with.
If the penetration exceeds 10, the solid writing body becomes too soft, making it difficult to write on, and when the handwriting is erased, the handwriting spreads on the paper surface (the wax becomes a thin layer), which can stain the blank areas on the written surface or can easily transfer color or stain other papers.
The softening point and penetration of the polyolefin wax can be measured in accordance with the measurement method specified in JIS K2207, with a penetration value of 0.1 mm being expressed as a penetration of 1. In other words, the smaller the penetration value of the solid writing material, the harder it is, and the larger the penetration value, the softer it is.

Specific examples of polyolefin waxes include Yasuhara Chemical Co., Ltd. (product name: Neowax series), Sanyo Chemical Industries, Ltd. (product name: Sunwax series), Mitsui Chemicals, Inc. (product name: Hiwax series), and Honeywell Co., Ltd. (product name: A-C polyethylene).

As the sucrose fatty acid ester, esters containing fatty acids having 12 to 22 carbon atoms as constituent fatty acids are preferred, and palmitic acid and stearic acid are more preferred.
Specific examples of sucrose fatty acid esters include those manufactured by Mitsubishi Chemical Foods Corporation under the product name Ryoto Sugar Ester Series, and those manufactured by Daiichi Kogyo Seiyaku Co., Ltd. under the product name Sugar Wax Series.

As the dextrin fatty acid ester, esters having a fatty acid of 14 to 18 carbon atoms as a constituent fatty acid are preferred, and palmitic acid, myristic acid, and stearic acid are more preferred. Specific examples of the dextrin fatty acid ester include those manufactured by Chiba Flour Milling Co., Ltd. under the product name: Leopearl series.

In addition, side-chain crystalline polyolefin is preferred as the excipient used in solid writing material.Here, side-chain crystalline polyolefin has a structure in which a relatively long side chain is bonded to a linear main chain.Normal linear polyolefin is likely to melt in a wide temperature range because its linear main chain is folded and crystallized, whereas side-chain crystalline polyolefin mainly crystallizes not in polyolefin main chain but in side chain, resulting in low melting point (Mp) and melting in a narrow temperature range.
Among such side chain crystalline polyolefins, those having in the side chain a long chain alkyl group having 12 to 28 carbon atoms are particularly preferred. The long chain alkyl group in the side chain is not particularly limited and may be either linear or branched, but linear long chain alkyl groups are preferred because they provide excellent crystallinity.
The alkyl group on the side chain may have a substituent, but the crystallinity is likely to decrease due to the substituent, and therefore, in order to adjust the crystallinity, the side chain of the side chain crystalline polyolefin may be modified with, for example, styrene, etc. Furthermore, if the long chain alkyl group has a functional group that forms a hydrogen bond, the long chain alkyl groups are bonded to each other by the hydrogen bond and aggregate, which improves the crystallinity, and is therefore preferable.

Side-chain crystalline polyolefins also include polyolefins with a highly branched structure (hereafter referred to as "highly branched polyolefins"), which can also be used as excipients. Highly branched polyolefins have a low melting point and melt in a narrow temperature range because the main chain is less likely to fold during crystallization.

In order to provide a solid writing material with excellent mechanical strength and thermal discoloration properties, and to be easy to handle during production, the excipient preferably has a weight average molecular weight (Mw) of 2,000 to 50,000, more preferably 10,000 to 30,000. Also, the number average molecular weight (Mn) is preferably 1,000 to 10,000.
The weight average molecular weight and number average molecular weight are values measured by gel permeation chromatography (GPC) using polystyrene as a standard.

Specific examples of side chain crystalline polyolefins include those manufactured by Toyokuni Oil Mills Co., Ltd., product names: HS Crysta 4100 (Mw: 16,000, Mp: 44.4°C) and HS Crysta 6100 (Mw: 28,000, melting point: 60.6°C), and those manufactured by Idemitsu Kosan Co., Ltd., product names: El Crysta 4100 (Mw: 16,000) and HS Crysta 6100 (Mw: 28,000).
Specific examples of highly branched polyolefins include those manufactured by Baker Hughes Corporation, product names: VYBAR 103 (Mw: 17,348, Mn: 4,400, Mp: 67.7° C.), VYBAR 260 (Mw: 20,278, Mn: 2,600, Mp: 54.7° C.), VYBAR 343 (Mw: 10,164, Mp: 36.0° C.), and VYBAR 825 (Mn: 2,800).

The filler is preferably blended in the range of 0.2 to 70% by mass, more preferably 0.5 to 40% by mass, based on the total amount of the solid writing material. By blending the filler in the above range, the shape of the solid writing material can be easily obtained, and the writing density of the solid writing material can be easily increased.
If the blending ratio of the excipient exceeds 70% by mass, it becomes difficult to obtain a sufficient writing density, whereas if the blending ratio of the excipient is less than 0.2% by mass, it becomes difficult to obtain a shape suitable for a writable core material.

Furthermore, by blending a filler into the solid writing material, it is possible to improve the strength of the solid writing material and adjust the writing feel.
Examples of the filler include talc, clay, silica, calcium carbonate, barium sulfate, alumina, mica, boron nitride, potassium titanate, and glass flakes.
Among the above fillers, talc or calcium carbonate is preferred because it has excellent moldability and is unlikely to impair the thermochromic properties when a microencapsulated pigment is used.

The filler is preferably blended in the range of 10 to 65% by mass based on the total amount of the solid writing material. If the blending ratio of the filler exceeds 65% by mass, the color development and writing feel tend to deteriorate. On the other hand, if the blending ratio of the filler is less than 10% by mass, the strength of the solid writing material tends to deteriorate.

Furthermore, by blending a binder resin in the solid writing material, the strength of the solid writing material can be improved.
Examples of the binder resin include natural resins and synthetic resins, such as olefin resins, cellulose resins, vinyl alcohol resins, pyrrolidone resins, acrylic resins, styrene resins, amide resins, and basic group-containing resins.
Among the above-mentioned binder resins, ethylene-vinyl acetate copolymer resins, ethylene-vinyl alcohol copolymer resins, and polyvinyl alcohol resins are preferred, and the molding stability can be improved by using these resins in combination with polyester polyol resins.
The binder resin is preferably blended in an amount of 0.5 to 5% by mass based on the total amount of the solid writing material.

In addition, by blending a hindered amine compound into the solid writing material, it is possible to make it difficult to visually recognize the residual image at the part where the writing has been erased from the writing surface. This makes it possible to satisfy re-writing properties without impairing the appearance of the writing surface, and to improve marketability.

The hindered amine compound preferably has a molecular weight of 1000 or less, since it has high compatibility with other components, is less likely to bleed out, and can form clear handwritten marks even after aging.
The melting point is preferably 120° C. or lower. A low melting point makes it possible to produce a solid writing material without applying excessive heat during production, and to prevent deterioration of a reversible thermochromic colorant, such as a reversible thermochromic composition, a reversible thermochromic microcapsule pigment, or resin particles, contained in the solid writing material.

In addition, various additives can be added as necessary.
Examples of the additives include viscosity adjusters, antifungal agents or preservatives, antibacterial agents, ultraviolet protection agents, antioxidants, lubricants, and fragrances.

The solid writing material may be used alone as a writing material, or may be used as an inner core with an outer shell covering the outer periphery thereof to form a core-sheath structure (double core).
The outer shell prevents the solid writing body (core) inside from being damaged by physical contact, and contributes to improving the mechanical strength of the entire solid writing body. The outer shell may or may not contain a reversible thermochromic colorant such as a reversible thermochromic composition, a reversible thermochromic microcapsule pigment, or a resin particle that contributes to the formation of handwriting, but since the tip of the solid writing body is generally cut into a cone shape, the outer shell often does not affect the handwriting. Therefore, it is common not to mix a reversible thermochromic colorant into the outer shell.

If necessary, various additives can be added to the shell.
Examples of the additives include non-thermochromic colorants, antifungal agents or preservatives, antibacterial agents, ultraviolet absorbers, antioxidants, lubricants, and fragrances.

The solid writing material can be produced by a production method such as extrusion molding or compression molding.
The above-mentioned solid writing material having a core-sheath structure in which an outer shell is provided to cover the outer surface of the inner core can be manufactured, for example, by a manufacturing method in which an outer shell is disposed on the outer surface of a lump of the inner core and compression molded using a press.

The thickness and length of the solid writing material are selected as desired depending on the purpose. For example, when the solid writing material is used as a pencil lead, the general thickness is 2.0 to 5.0 mm, preferably 2.5 to 4.0 mm. The length is 60 to 300 mm, preferably 80 to 200 mm.

In addition, when the solid writing material has a core-sheath structure, the thickness of the inner core and the thickness of the outer shell are also selected arbitrarily. A thicker outer shell provides better impact resistance, while a thinner outer shell provides a larger amount of exposed inner core, which tends to provide better usability. The thickness of the outer shell relative to the radial length of the inner core is preferably in the range of 10 to 100%, more preferably 20 to 50%.
The thickness and length of the solid writing material are appropriately adjusted depending on the application other than pencil, for example, lead for mechanical pencils, crayons, etc.

The solid writing material can be used to write on various writing surfaces, and furthermore, since it uses a reversible thermochromic colorant such as a reversible thermochromic composition, a reversible thermochromic microencapsulated pigment, or resin particles, the handwriting written on the writing surface can be discolored by rubbing with a finger or by applying the heating or cooling tool described above. As the color can be discolored by a simple method, the friction member described above is preferred as the heating tool.

A solid writing body set can also be obtained by combining a solid writing body with a friction member (friction body) of any shape that is separate from the solid writing body, but by providing a friction member to the solid writing body or to the exterior of a solid writing implement in which the solid writing body is contained in an exterior container, it can be made highly portable. Specifically, examples include a form in which a friction member is provided on an exterior in the shape of a pencil, crayon, etc., made of wood or paper.

Furthermore, a reversible thermochromic composition, a reversible thermochromic colorant such as a reversible thermochromic microcapsule pigment or resin particles can be melt-blended with a thermoplastic resin, a thermosetting resin, wax, or the like to form pellets, powder, or paste, and used as a reversible thermochromic molding resin composition.
The reversible thermochromic molding resin composition can be subjected to general-purpose injection molding, extrusion molding, blow molding, cast molding or the like to obtain molded articles in the form of three-dimensional objects of any shape, films, sheets, plates, filaments, rods, pipes, and the like.
Moreover, by melt-blending it with a thermoplastic resin, a toner or powder coating material can be obtained.

The reversible thermochromic liquid composition, the solid molding for coating, and the molding resin composition exhibit a color change behavior from colored (1) to colored (2) by blending a non-thermochromic colorant such as a general dye or pigment.

A layer containing a light stabilizer and/or a transparent metallic luster pigment can be laminated on the molded body or laminate to improve light resistance, or a top coat layer can be provided to improve durability.
Examples of light stabilizers include ultraviolet absorbers, antioxidants, singlet oxygen quenchers, superoxide anion quenchers, and ozone quenchers.
Examples of the transparent metallic luster pigment include pigments having a core material such as natural mica, synthetic mica, glass pieces, alumina, and transparent film pieces whose surfaces are coated with a metal oxide such as titanium oxide.

Specific examples of products using the reversible thermochromic composition and the microencapsulated pigment or resin particles encapsulating the same include the following.
(1) Toys Dolls and animal-shaped toys, hair for dolls and animal-shaped toys, doll houses and furniture, clothing, doll accessories such as hats, bags, shoes, etc., accessory toys, stuffed toys, drawing toys, toy picture books, puzzle toys such as jigsaw puzzles, building block toys, block toys, clay toys, fluid toys, tops, kites, musical instrument toys, cooking toys, gun toys, capture toys, background toys, toys imitating vehicles, animals, plants, buildings, food, etc.
(2) Clothing: T-shirts, sweatshirts, blouses, dresses, swimsuits, raincoats, skiwear, and other clothing; footwear such as shoes and shoelaces; cloth accessories such as handkerchiefs, towels, and wrapping cloths; gloves, ties, hats, scarves, mufflers, etc.
(3) Indoor decorations: Carpets, curtains, curtain strings, table hangings, rugs, cushions, carpets, rugs, chair upholstery, seats, mats, picture frames, artificial flowers, photo frames, etc.
(4) Furniture: Bedding such as futons, pillows, mattresses, lighting fixtures, heating and cooling equipment, etc.
(5) Accessories: Rings, bracelets, tiaras, earrings, hairpins, false nails, ribbons, scarves, watches, glasses, etc.
(6) Stationery: Writing implements, stamps, erasers, writing pads, rulers, notebooks, adhesive tape, etc.
(7) Daily necessities: lipstick, eye shadow, foundation, eyeliner, eyebrows, nail polish, hair dye, false nails, paint for false nails, and other cosmetics, toothbrushes, etc.
(8) Kitchen utensils: cups, plates, chopsticks, spoons, forks, pots, frying pans, etc.
(9) Others Calendars, labels, cards, recording materials, various anti-counterfeiting printed materials, picture books and other books, bags, packaging containers, embroidery thread, sports equipment, fishing tackle, coasters, musical instruments, hand warmers, ice packs, wallets and other bags, umbrellas, vehicles, buildings, temperature detection indicators, teaching tools, etc.

Examples are shown below. In the examples, "parts" refers to parts by weight.
Example 1
Preparation of reversible thermochromic composition 4 parts of 2-(3-trifluoromethylanilino)-6-(dipentylaminofluoran as component (A), 5 parts of urea, N-[3-[[(4-tert-butylphenyl)sulfonyl]oxy]phenyl]-N-phenyl- as component (B), 25 parts of myristyl alcohol and 25 parts of butyl stearate as component (C) were mixed and dissolved by heating to obtain a reversible thermochromic composition which changes color from black to colorless.

Example 2
Preparation of reversible thermochromic microcapsule pigment A reversible thermochromic composition was prepared by mixing 4 parts of 2-(3-trifluoromethylanilino)-6-(dipentylaminofluoran as component (A), 5 parts of urea, N-[3-[[(4-methylphenyl)sulfonyl]oxy]phenyl]-N-phenyl- as component (B), and 50 parts of 4-benzyloxyphenylethyl caprate as component (C), and a microcapsule pigment suspension was obtained in which the pigment was encapsulated in microcapsules by an interfacial polymerization method.
The pigment was isolated from the microcapsule pigment suspension by centrifugation to obtain a reversible thermochromic microcapsule pigment that changed color from black to colorless and had an average particle size of 2 μm.

Example 3
Preparation of reversible thermochromic microcapsule pigment A reversible thermochromic composition was prepared by mixing 4 parts of 2-(3-trifluoromethylanilino)-6-(dipentylaminofluoran as component (A), 5 parts of urea, N-[3-[[(4-methyloxyphenyl)sulfonyl]oxy]phenyl]-N-phenyl- as component (B), and 50 parts of 4-benzyloxyphenylethyl caprate as component (C), and a microcapsule pigment suspension was obtained in which the pigment was encapsulated in microcapsules by an interfacial polymerization method.
The pigment was isolated from the microcapsule pigment suspension by centrifugation to obtain a reversible thermochromic microcapsule pigment that changed color from black to colorless and had an average particle size of 2 μm.

Example 4
Preparation of reversible thermochromic microcapsule pigment A reversible thermochromic composition was prepared by mixing 4 parts of 2-(3-trifluoromethylanilino)-6-(dipentylaminofluoran as component (A), 5 parts of urea, N-[3-[[(4-chlorophenyl)sulfonyl]oxy]phenyl]-N-phenyl- as component (B), and 50 parts of 4-benzyloxyphenylethyl caprate as component (C), and a microcapsule pigment suspension was obtained in which the pigment was encapsulated in microcapsules by an interfacial polymerization method.
The pigment was isolated from the microcapsule pigment suspension by centrifugation to obtain a reversible thermochromic microcapsule pigment that changed color from black to colorless and had an average particle size of 2 μm.

Example 5
Preparation of reversible thermochromic microcapsule pigment A reversible thermochromic composition was prepared by mixing 2 parts of 3',6'-bis[phenyl(3-methylphenyl)amino]-spiro[isobenzofuran-1(3H),9'-[9H]xanthene]-3-one as component (A), 5 parts of urea, N-[3-[[(4-methylphenyl)sulfonyl]oxy]phenyl]-N-phenyl- as component (B), and 50 parts of 4-benzyloxyphenylethyl caprate as component (C), and a microcapsule pigment suspension was obtained in which the pigment was encapsulated in microcapsules by an interfacial polymerization method.
The pigment was isolated from the microcapsule pigment suspension by centrifugation to obtain a reversible thermochromic microcapsule pigment having an average particle size of 2 μm and changing color from blue to colorless.

Example 6
Preparation of reversible thermochromic microcapsule pigment A reversible thermochromic composition was prepared by mixing 3 parts of 9-ethyl(3-methylbutyl)amino-spiro[12H-benzo(a)xanthen-12,1'(3'H)isobenzofuran]-3'-one as component (a) and 50 parts of 4-benzyloxyphenylethyl caprate as component (c), and a microcapsule pigment suspension was obtained in which the pigment was encapsulated in microcapsules by interfacial polymerization.
The pigment was isolated from the microcapsule pigment suspension by centrifugation to obtain a reversible thermochromic microcapsule pigment having an average particle size of 2 μm and changing color from pink to colorless.

Example 7
Preparation of reversible thermochromic microcapsule pigment A reversible thermochromic composition was prepared by mixing 4 parts of 2-(3-trifluoromethylanilino)-6-(dipentylaminofluoran as component (A), 5 parts of urea, N-[3-[[(4-tert-butylphenyl)sulfonyl]oxy]phenyl]-N-phenyl- as component (B), and 50 parts of neopentyl stearate as component (C), and a microcapsule pigment suspension was obtained in which the pigment was encapsulated in microcapsules by an interfacial polymerization method.
The pigment was isolated from the microcapsule pigment suspension by centrifugation to obtain a reversible thermochromic microcapsule pigment that changed color from black to colorless and had an average particle size of 2 μm.

Preparation of Measurement Sample The reversible thermochromic composition of Example 1 was filled into a transparent glass capillary tube having an inner diameter of 1 mm and a length of 78 mm to a height of about 10 mm from the bottom of the capillary tube to obtain a measurement sample.
The entire portion of the measurement sample in which the reversible thermochromic composition was encapsulated was immersed in a transparent heat medium, and the discoloration state of the reversible thermochromic composition was visually observed while changing the temperature of the transparent heat medium, and _t1 (complete color development temperature), _t2 (color development onset temperature), t3 (discoloration onset temperature), _t4 (complete discoloration temperature), and ΔH (hysteresis width: intermediate temperature between _t3 and _t4 - intermediate temperature between _t1 and _t2 ) were determined.
Reversible thermochromic inks were prepared by uniformly dispersing 40 parts of the reversible thermochromic microencapsulated pigments of Examples 2 to 6 in an aqueous ink vehicle consisting of 50 parts of ethylene-vinyl acetate resin emulsion, 1 part of leveling agent, 1 part of defoaming agent, 0.5 parts of viscosity modifier, and 7.5 parts of water.
A solid pattern was screen-printed on fine paper using the ink to obtain a measurement sample.
The measurement sample was set in the measurement portion of a color difference meter (TC-3600 color difference meter, manufactured by Tokyo Denshoku Co., Ltd.), the temperature of the sample portion was increased and decreased at a rate of 2°C/min, and the lightness value was measured as the color density at each temperature, and a color density-temperature curve was created. From the color density-temperature curve, _t1 (complete color development temperature), _t2 (color development start temperature), _t3 (color disappearance start temperature), _t4 (complete disappearance temperature), and ΔH (hysteresis width: intermediate temperature between _t3 and _t4 - intermediate temperature between _t1 and _t2 ) were obtained.
The test results are shown in Table 1 below.

Application example 1
Preparation of Ballpoint Pen A reversible thermochromic ink composition was prepared consisting of 20 parts of the reversible thermochromic microencapsulated pigment prepared in Example 2 (previously cooled to -18°C or below to develop a black color), 0.3 parts of xanthan gum, 10 parts of urea, 10 parts of glycerin, 0.5 parts of a nonionic penetrant, 0.1 parts of a modified silicone antifoaming agent, 0.2 parts of a preservative, and 58.9 parts of water.
The reversible thermochromic ink composition was filled into a polypropylene pipe by suction, and the pipe was connected via a resin holder to a ballpoint pen tip having a 0.5 mm stainless steel ball at its tip.
Next, a viscoelastic ink backflow prevention material (liquid plug) mainly composed of polybutene was filled into the rear end of the polypropylene pipe, and a tail plug was then fitted to the rear of the pipe.The front and rear barrels were then assembled, and a cap was then fitted.Then, the pen was degassed by centrifugation to obtain a ballpoint pen.
In addition, a SEBS resin is attached to the rear portion of the rear barrel as a friction body.
The ballpoint pen was used to write on the surface of paper to form black characters (handwriting).
The handwriting was black at room temperature (25° C.), and when the characters were rubbed with a friction body, the characters were erased and became colorless, and this state could be maintained unless the characters were cooled to −18° C. or lower.
When the paper surface was placed in a freezer and cooled to −18° C. or lower, the letters again turned black, and this discoloration behavior could be reproduced repeatedly.

Application example 2
Preparation of Marking Pen 25.0 parts of the reversible thermochromic microcapsule pigment prepared in Example 2 (previously cooled to -18°C or less to develop a black color), 0.5 parts of a comb-type polymer dispersant [manufactured by Lubrizol Japan, product name: Solsperse 43000], 1.0 parts of an organic nitrogen sulfur compound [manufactured by Hokko Chemical Industry Co., Ltd., product name: Hokuside R-150, a mixture of 2-methyl-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one], 0.5 parts of polyvinyl alcohol, 35.0 parts of glycerin, 0.02 parts of an antifoaming agent, and 37.98 parts of water were mixed to obtain a reversible thermochromic ink composition.
The ink composition was impregnated into an ink occlusion body made of polyester sliver covered with a synthetic resin film, and the ink was housed in a barrel made of polypropylene resin. A resin-processed pen body (chisel type) made of polyester fiber was assembled to the tip of the barrel in a connected state via a holder, and a cap was attached to obtain a marking pen.
The rear end of the barrel is fitted with SEBS resin as a friction member.
The marking pen was used to write on the surface of the paper to form black characters (handwriting).
The handwriting was black at room temperature (25° C.), and when the characters were rubbed with a friction body, the characters were erased and became colorless, and this state could be maintained unless the characters were cooled to −18° C. or lower.
When the paper surface was placed in a freezer and cooled to −18° C. or lower, the letters again turned black, and this discoloration behavior could be reproduced repeatedly.

Application example 3
Preparation of a solid writing body 40 parts of the reversible thermochromic microcapsule pigment prepared in Example 5 (previously cooled to -17 ° C or less to develop a blue color), 35 parts of talc (filler), 10 parts of a side chain crystalline polyolefin (excipient) [Toyokuni Oil Mill Co., Ltd., product name: HS Crystal 4100], 10 parts of a polyolefin wax (excipient) [Sanyo Chemical Industries, Ltd., product name: Sunwax 131-P (softening point 110 ° C, needle penetration 3.5)], 2 parts of a styrene-acrylic acid copolymer resin, 2 parts of a polyvinyl alcohol resin, and 1 part of a hindered amine light stabilizer were kneaded in a kneader to prepare a kneaded product for the inner core.
Next, 69 parts of talc (filler), 10 parts of sucrose fatty acid ester, 10 parts of polyolefin wax (filler), and 10 parts of ethylene-vinyl acetate copolymer were kneaded in a kneader to prepare a kneaded material for the outer shell.
The kneaded material for the outer shell was wrapped around the outer peripheral surface of the kneaded material for the inner core so that the kneaded material for the inner core became the inner core, and compression molding was performed with a press to form a solid writing body with a core-sheath structure having an outer diameter of φ3 mm and a length of 60 mm (the inner core was φ2 mm, and the covering thickness of the outer shell was 0.5 mm). Note that the above dimensions are set values, and the solid writing body was manufactured by cooling to −17° C. after compression molding and returning to room temperature.
The solid writing body was molded and housed in a round outer shaft (wooden shaft) to obtain a pencil. Furthermore, a cylindrical friction body made of SEBS resin was fixed to the rear end of the pencil via a metal connecting member to prepare a solid writing implement with a friction body (a pencil with a friction body).
When blue characters (handwriting) were formed on a paper surface using the solid writing instrument, the handwriting exhibited a blue color at room temperature (25°C). When the characters were rubbed with a friction member, the characters were erased and became colorless, and this state could be maintained unless the characters were cooled to -17°C or below.
Furthermore, when the paper surface was placed in a freezer and cooled to below -17°C, the letters again turned blue, and this discoloration behavior could be reproduced repeatedly.

Application example 4
Preparation of Stamp A reversible thermochromic ink for stamps was prepared by mixing 20 parts of the reversible thermochromic microcapsule pigment prepared in Example 6 (previously cooled to -18°C or lower to develop a pink color), 50 parts of glycerin, 1.5 parts of an alkali-soluble acrylic emulsion (manufactured by Rohm and Haas Japan Co., Ltd., product name: Primal DR73), 0.9 parts of triethanolamine, 10 parts of a 50% aqueous solution of polyvinylpyrrolidone, 0.2 parts of a silicon-based defoamer, 0.5 parts of a penetrating leveling agent, 0.2 parts of a preservative, and 16.7 parts of water.
The ink for stamping was impregnated into a stamp material having continuous pores, and the stamp material was fixed to a stamp base material so that the printing surface of the stamp material was exposed, and a cap was fitted to prepare a stamp.
The rear end of the stamp base material is fitted with SEBS resin as a friction member.
When the stamp was repeatedly pressed against the surface to be stamped (paper surface), the ink flowed smoothly from the printing surface of the printing material and transferred to the surface to be stamped, allowing clear images to be continuously formed without bleeding.
The printed image had a pink color at room temperature (25° C.), and when rubbed with a friction member, the printed image was erased and became colorless, and this state could be maintained unless it was cooled to −18° C. or lower.
Furthermore, when the paper surface was placed in a freezer and cooled to below -18°C, the print image again showed a discoloration behavior that turned pink, and this discoloration behavior could be repeatedly reproduced.

Application example 5
Preparation of reversible thermochromic printed matter A reversible thermochromic offset ink was prepared by mixing 30 parts of the reversible thermochromic microcapsule pigment prepared in Example 3 (previously cooled to -18°C or below to develop a black color), 5 parts of a red dye, and 65 parts of a linseed oil-based offset ink vehicle.
The offset ink was used for offset printing on both sides of a sheet of wood-free paper as a printing medium, and the ink was dried and cured to form a date (thermochromic image).
The thermochromic images on the front and back sides are formed so as not to overlap each other.
Next, offset printing was carried out using a non-discoloring black offset ink, which was then dried and cured to form a frame line (non-discoloring image), thereby producing a reversible thermochromic printed matter.
The reversible thermochromic printed matter is initially a notebook-type printed matter with black dates printed on it, but it can be changed in color to red by rubbing the thermochromic image at any point on the surface with a friction member, and the changed color can be maintained at room temperature (25°C), making it useful for managing holiday schedules.
In addition, the dates written on the reverse side of the discolored areas were not discolored by heat when the thermochromic image on the front side was discolored, allowing for accurate schedule management.

Application Example 6
Preparation of a reversible thermochromic indicator A reversible thermochromic indicator was prepared by printing a reversible thermochromic layer on the surface of a white polyester film (thickness 25 μm) used as a support using an ink in which the reversible thermochromic microcapsule pigment prepared in Example 2 was dispersed in a vehicle containing a binder resin, and then a transparent polyester film having a thickness of 16 μm was laminated on the upper surface to obtain a reversible thermochromic indicator.
The display was once cooled to -18°C or lower to cause the reversible thermochromic layer to completely develop a black color, after which white cut-out characters were printed using a thermal transfer printer.
The white outline characters are visible as long as the display body is maintained within a temperature range of -18°C to 64°C.
Furthermore, when the display body was cooled again to below -18°C and the reversible thermochromic layer was caused to completely turn black, the white cut-out characters were no longer visible, and by forming white cut-out characters using the thermal transfer printer, the display body could be used repeatedly.

Application Example 7
Preparation of dolls Five parts of the reversible thermochromic microcapsule pigment prepared in Example 7, one part of dispersant, 94 parts of nylon 12 with a melting point of 180°C, and 0.1 parts of a general pink pigment were melt-mixed at 200°C in an extruder to prepare reversible thermochromic pellets for the core.
The reversible thermochromic pellets were fed to an extruder for molding the core, and the nylon 12 natural pellets were fed to an extruder for molding the sheath. Using a composite fiber spinning device, the fibers were spun at 200°C from 18 discharge holes so that the volume ratio of the core:sheath was 6:4, to prepare a reversible thermochromic composite fiber consisting of 18 single yarns with an outer diameter of 90 μm.
Furthermore, the reversible thermochromic composite fiber was implanted in the hair of a doll by a conventional method, to prepare a doll equipped with hair made of the reversible thermochromic composite fiber.
The doll's hair was once cooled to below 13°C and completely colored black. When it was then immersed in warm water at 32°C, it changed from black to pink. When it was taken out of the warm water and immersed in cold water at 13°C, it changed back to black. This change could be repeated.

Application Example 8
Preparation of reversible thermochromic miniature car 15 parts of the reversible thermochromic microcapsule pigment prepared in Example 7, 40 parts of a 50% acrylic resin/xylene solution, 20 parts of xylene, 20 parts of methyl isobutyl ketone, and 5 parts of a polyisocyanate-based hardener were mixed and stirred into a vehicle to obtain a reversible thermochromic spray paint.
The reversible thermochromic spray paint was sprayed onto the entire body of a white miniature car and dried to provide a reversible thermochromic layer, thereby obtaining a reversible thermochromic miniature car (toy).
The miniature car was once cooled to 13° C. or less, and the reversible thermochromic layer was completely colored black. Then, when the car was immersed in hot water at 32° C., it turned white. When the car was removed from the hot water and immersed in cold water at 13° C., it turned black again, and the above-mentioned behavior could be repeated.

Application Example 9
Preparation of a reversible thermochromic mug 30 parts of the reversible thermochromic microcapsule pigment prepared in Example 7, 60 parts of a hard liquid epoxy resin, 2 parts of an ultraviolet absorber, 2 parts of a thixotropy imparting agent, and 0.5 parts of an antifoaming agent were mixed, and 40 parts of a room temperature curing aliphatic polyamine was further added to obtain a reversible thermochromic epoxy ink.
Using the reversible thermochromic epoxy ink, a polka dot pattern was printed on the side of a ceramic mug using a stainless steel screen plate and a curved surface printing machine, and the pattern was then heated and cured at 70°C for 1 hour to form a reversible thermochromic layer, thereby obtaining a reversible thermochromic mug.
When cold water below 13°C is poured into the mug, the reversible thermochromic layer turns black and the polka dot pattern is visible, but when the cold water is removed from this state and hot water at 32°C is poured, the reversible thermochromic layer disappears and becomes colorless. When the hot water is removed from this state and cold water at 13°C is poured, the reversible thermochromic layer turns color and the black polka dot pattern is visible again.
This change in appearance could be repeated by changing the temperature.

t1 Complete coloring temperature t2 Coloring start temperature t3 Discoloration start temperature t4 Complete discoloration temperature ΔH Hysteresis width

Claims (17)

A reversible thermochromic composition comprising: (a) an electron-donating organic color-forming compound; (b) a compound represented by formula (1) as an electron-accepting compound; and (c) a reaction medium that reversibly induces an electron donor-acceptor reaction between the components (a) and (b) in a specific temperature range.

(In formula (1), R ₁ to R ₅ each independently represent a hydrogen atom, a halogen atom, a nitro group, an amino group, an alkyl group, an alkoxy group, an aryloxy group, an alkylcarbonyloxy group, an arylcarbonyloxy group, an alkylcarbonylamino group, an arylcarbonylamino group, an alkylsulfonylamino group, an arylsulfonylamino group, a monoalkylamino group, a dialkylamino group, or an arylamino group.) 2. The reversible thermochromic composition according to claim 1, wherein the compound of formula (1) is a compound represented by formula (2).

(In formula (2), _R3 represents a hydrogen atom, a halogen atom, a nitro group, an amino group, an alkyl group, an alkoxy group, an aryloxy group, an alkylcarbonyloxy group, an arylcarbonyloxy group, an alkylcarbonylamino group, an arylcarbonylamino group, an alkylsulfonylamino group, an arylsulfonylamino group, a monoalkylamino group, a dialkylamino group, or an arylamino group.) 3. The reversible thermochromic composition according to claim 2, wherein in formula (2), _R3 is any one of a fluorine atom, a chlorine atom, a bromine atom, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, and an aryloxy group having 6 to 12 carbon atoms. The reversible thermochromic composition according to any one of claims 1 to 3, containing 0.1 to 100 parts by mass of component (b) and 5 to 200 parts by mass of component (c) per 1 part by mass of component (a). The reversible thermochromic composition according to claim 4, which contains 0.1 to 50 parts by mass of component (b) and 5 to 100 parts by mass of component (c) per 1 part by mass of component (a). A reversible thermochromic microcapsule pigment encapsulating the reversible thermochromic composition according to any one of claims 1 to 5. A reversible thermochromic liquid composition comprising the reversible thermochromic microcapsule pigment according to claim 6 and a vehicle. The reversible thermochromic liquid composition according to claim 7, which is selected from the group consisting of printing ink, writing ink, coating ink, stamp ink, inkjet ink, paint, ultraviolet-curable ink, paint, cosmetics, and coloring liquid for fibers. A reversible thermochromic solid molding for coating comprising the reversible thermochromic microcapsule pigment according to claim 6 and an excipient. The reversible thermochromic solid molding for application according to claim 9, which is a solid writing material or a solid cosmetic product. A reversible thermochromic molding resin composition comprising the reversible thermochromic microcapsule pigment according to claim 6 and a molding resin. A reversible thermochromic molded article obtained by molding the reversible thermochromic molding resin composition according to claim 11. A reversible thermochromic laminate comprising a support and a reversible thermochromic layer comprising the reversible thermochromic microcapsule pigment according to claim 6. A writing instrument containing the writing instrument ink according to claim 8. The writing instrument according to claim 14, wherein the writing instrument is a ballpoint pen. The writing instrument according to claim 14, wherein the writing instrument is a marking pen. The writing instrument according to any one of claims 14 to 16, comprising a friction member that discolors handwriting made with the writing instrument due to frictional heat.

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