JP3353989B2 - Thermal recording material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording material, and more particularly to a heat-sensitive recording material having improved color developability, raw storage stability and stability of a color image.

[0002]

2. Description of the Related Art Recording materials using an electron-donating colorless dye and an electron-accepting compound include pressure-sensitive paper, heat-sensitive paper, photosensitive pressure-sensitive paper,
It is already well-known as an energized thermal recording paper, a thermal transfer paper, and the like. For example, British Patent Nos. 2,140,449, U.S. Patent Nos. 4,480,052 and 4,436,920
No., JP-B-60-23992, JP-A-57-1798
No. 36, No. 60-123556, No. 60-12355
No. 7 and more. In particular, the heat-sensitive recording material is disclosed in
No. 4160 and Japanese Patent Publication No. 45-14039. These thermal recording systems are applied to various fields such as facsimile machines, printers, labels, and the like, and needs are expanding. However, the heat-sensitive recording material has a drawback that fogging is caused by a solvent and the like, and a color-forming body is discolored and discolored by oils and fats, chemicals, etc., so that labels, slips, word processing paper, plotters and the like are used. In the field of paper and the like, the commercial value has been significantly impaired. The present inventors have determined that, for each of the electron-donating colorless dye and the electron-accepting compound, their oil solubility, solubility in water, partition coefficient, p
Focusing on Ka, the polarity of the substituent, and the position of the substituent, the development of good recording material and recording material has been pursued.
However, providing these resistances has caused a problem that the sensitivity is significantly reduced.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a heat-sensitive recording material having high sensitivity, good raw storability, and good printing quality with good stability of a color image.

[0004]

An object of the present invention is to provide a heat-sensitive recording material comprising a support having thereon a heat-sensitive coloring layer containing an electron-donating colorless dye and an electron-accepting compound. N- represented by the following general formula (I)
A substituted anthranilic acid derivative or a metal salt thereof, (2)
Di (p-methylbenzyl) oxalate, 2-benzyloxy
Naphthalene, parabenzylbiphenyl, metaterphenyl
, 4-biphenyl-p-tolyl ether, 1,2-di
Selected from the group consisting of (3-methylphenoxy) ethane
Sensitizer, and (3) an aliphatic amide compound .

[0005]

Embedded image

[0006]

In the above formula, R ₁ represents a hydrogen atom, an alkyl group or an aryl group; R ₂ represents an alkyl group, a cycloalkyl group, an aryl group, an alkylamino group, an alkyloxy group, an aryloxy group or an arylamino group; X
Represents an oxygen atom or a sulfur atom, M represents an n-valent metal atom,
n represents an integer.

In the general formula (I) , preferably, R ₁
Is a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a monocyclic or fused ring aryl group having 6 to 10 carbon atoms,
R ₂ is a linear or branched alkyl group having 4 to 20 carbon atoms,
Substituted alkyl groups (substituents include aryl groups, carboxyl groups, sulfo groups, sulfoamino groups, aryloxy groups, alkyloxy groups, acylamino groups, etc.),
A cycloalkyl group having 5 to 9 carbon atoms, a monocyclic or condensed ring aryl group having 6 to 10 carbon atoms, or a substituted aryl group (as the substituent, an alkyl group having 1 to 20 carbon atoms, a hydroxyl group, an aryl group, a carboxyl group , A sulfo group, a sulfoamino group,
An acylamino group, and the like. ), An alkylamino group having 1 to 20 carbon atoms, a substituted alkylamino group (as the substituent, there are an aryl group, a carboxyl group, a sulfo group, a sulfamino group, an acylamino group, etc.), and a carbon number of 1 to 20.
Alkyloxy group, substituted alkyloxy group (substituents include an aryl group, a carboxyl group, a sulfo group, a sulfoamino group, an acylamino group, etc.), and having 1 to 1 carbon atoms.
20 aryloxy groups, substituted aryloxy groups (substituents include an alkyl group having 1 to 20 carbon atoms, a hydroxyl group, an aryl group, a carboxyl group, a sulfo group, a sulfoamino group, an acylamino group, etc.), and a carbon number of 6 And 10 to 10 arylamino groups and substituted arylamino groups (substituents include an alkyl group having 1 to 20 carbon atoms, a hydroxyl group, a carboxyl group, a sulfo group, a sulfoamino group, an acylamino group, and the like). Particularly preferably, R ₁ is a hydrogen atom, and R ₂ is an alkyl group having 7 to 17 carbon atoms, an alkoxy-substituted alkyl group, an aryloxy-substituted alkyl group,
An alkyloxy group having 7 to 17 carbon atoms, an aralkyloxy group, an aryl group having 6 to 18 carbon atoms, an alkyl-substituted aryl group, and an alkylamino group having 12 to 18 carbon atoms.

Specific examples of the electron-accepting compound according to the present invention are shown below. (1) N-caproylanthranilic acid, (2)
N-pivaloylanthranilic acid, (3) N-capryloylanthranilic acid, (4) N- (2-ethylhexanoyl) anthranilic acid, (5) N-decanoylanthranilic acid, (6) N-lauroylanthranilic acid Acid, (7) N
-Myristoylanthranilic acid, (8) N-palmitoylanthranilic acid, (9) N-stearoylanthranilic acid, (10) N- (cyclohexylcarbonyl) anne
Tolanic acid, (21) N- (octylcarbamoyl) a
Nthranilic acid, (22) N- (2-ethylhexylcarbamoyl) anthranilic acid, (23) N- (cyclohexylcarbamoyl) anthranilic acid, (24) N- (dodecylcarbamoyl) anthranilic acid, (25) N-
(Octadecylcarbamoyl) anthranilic acid, (2
6) N- (dodecylphenylcarbamoyl) anthranilic acid, (27) N- (cyclohexylthiocarbamoyl) anthranilic acid, (28) N- (octylthiocarbamoyl) anthranilic acid, (29) N- (2-ethylhexylthiocarbamoyl) Anthranilic acid, (30)
N- (dodecylthiocarbamoyl) anthranilic acid,

(31) N- (octadecylthiocarbamo)
Yl) anthranilic acid, (33) N-acetylanthra
Sulfonyl acid, (34) N-propionyl Ruan anthranilate,
(35) N- (n-butylcarbonyl) anthranilic acid, (36) N- (n-hexylcarbonyl) anthranilic acid, (37) N- (n-octylcarbonyl) anthranilic acid, (38) N-benzoylanthranilic acid ,
(39) N- (4-chlorobenzoyl) anthranilic acid, (40) N- (4-methoxybenzoyl) anthranilic acid, (41) N- (2-methoxybenzoyl) anthranilic acid, (42) N- (2- Methylthiobenzoyl) anthranilic acid, (43) N- (2-chlorobenzoyl) anthranilic acid, (44) N- (phenoxyacetyl) anthranilic acid, (45) N- (4-methoxyphenoxyacetyl) anthranilic acid, (46) N- (phenylacetyl) anthranilic acid, (47) N- (phenoxycarbonyl) anthranilic acid, (48) N- (benzyloxycarbonyl) anthranilic acid, (49) N
-(2-phenoxypropionyl) anthranilic acid,
(50) N- (3-phenoxypropionyl) anthranilic acid, (51) N- (methoxyacetyl) anthrani
Luic acid, (55) N- (methoxycarbonyl) anthrani
And (56) N- (ethoxycarbonyl) anthranilic acid, (57) N- (n-butyloxycarbonyl) anthranilic acid, and the like.

On the other hand, N represented by the general formula (I) of the present invention
-Substituted anthranilic acids exhibit remarkable color developing ability for the purpose of the present invention by converting their carboxyl groups into polyvalent metal salts. The polyvalent metal in this case is a typical element such as magnesium, calcium, aluminum, tin, titanium, titanium,
Transition elements such as vanadium, chromium, manganese, iron, cobalt, nickel, copper, and zinc. Especially the general formula
As the polyvalent metal salt of the N-substituted anthranilic acid represented by (I) , a zinc salt or an aluminum salt is preferable.
Among them, zinc salts have high color developing ability. The N-substituted anthranilic acid derivative represented by the general formula (I) is at least one of oxides, hydroxides, carbonates, and carboxylates such as zinc, aluminum, titanium, silicon, boron, magnesium, and calcium. When used together, the image storability is further improved.
Among the metal compounds used in combination, zinc oxide, aluminum hydroxide, calcium carbonate, silicon dioxide and aluminum silicate are preferred, and zinc oxide is particularly preferred.

According to the present invention, the dispersed particle size of the N-substituted anthranilic acid derivative or its metal salt after being atomized by a sand mill or the like should be as small as 3 μm or less, preferably 2 μm or less in order to obtain color development sensitivity. preferable.

The N-substituted anthranilic acid derivatives according to the present invention may be added to well-known salicylic acid derivatives, metal salts of aromatic carboxylic acids, phenol derivatives, phenol resins, novolak resins, metal-treated novolak resins, metal complexes, acidic An electron accepting compound such as clay or bentonite may be used in combination. These examples are shown in JP-B-40-9.
No. 309, JP-B-45-14039, JP-A-52-1
No. 40483, JP-A-48-51510, JP-A-57
JP-A-2108686, JP-A-58-87089, JP-A-59-11286, JP-A-60-176799, JP-A-61-95988, and the like.

Examples of some of these are 4-tert-butylphenol, 4-phenylphenol, 2,
2'-dihydroxybiphenyl, 2,2-bis (4-
Hydroxyphenyl) propane (bisphenol A),
4,4'-sec-butylidene diphenol, 4,4 '
-Cyclohexylidene diphenol, bis (3-allyl-4-hydroxyphenyl) sulfone, 4-hydroxyphenyl-3 ', 4'dimethylphenylsulfone, 4-
(4-isopropoxyphenylsulfonyl) phenol, 4,4′-dihydroxydiphenyl sulfide,
1,4-bis- (4′-hydroxycumyl) benzene,
1,3-bis- (4′-hydroxycumyl) benzene,
4,4′-thiobis (6-tert-butyl-3-methylphenol), 4,4′-dihydroxydiphenylsulfone, 4-hydroxybenzoic acid benzyl ester,
3,5-di-tert-butylsalicylic acid, 3-phenyl-5- (α, α-dimethylbenzyl) salicylic acid,
-Cumyl-5-t-octylsalicylic acid, 3,5-di-
t-butylsalicylic acid, 3-phenyl-5-t-octylsalicylic acid, 3-methyl-5-α-methylbenzylsalicylic acid, 3-methyl-5-cumylsalicylic acid, 3,5
-Di-t-octylsalicylic acid, 3,5-bis (α-methylbenzyl) salicylic acid, 3-cumyl-5-phenylsalicylic acid, 5-n-octadecylsalicylic acid, 4-pentadecylsalicylic acid, 3,5-bis (α , Α-dimethylbenzyl) salicylic acid, 3,5-bis-t-octylsalicylic acid, 4-β-dodecyloxyethoxysalicylic acid, 4-methoxy-6-dodecyloxysalicylic acid, 4
-Β-phenoxyethoxysalicylic acid, 4-β-p-ethylphenoxyethoxysalicylic acid, 4-β-p-methoxyphenoxyethoxysalicylic acid, and metal salts thereof. The electron-accepting compound N- according to the present invention
The above electron accepting compound is preferably mixed at a ratio of 10 to 100% by weight with respect to the substituted anthranilic acid derivative. Further, two or more of the above electron accepting compounds may be used in combination.

The electron-accepting compound is preferably used in an amount of 50 to 800% by weight, more preferably 100 to 500% by weight, based on the color of the electron-donating colorless dye.

Examples of the electron-donating colorless dye of the present invention include triphenylmethanephthalide compounds, fluoran compounds, phenothiazine compounds, indolylphthalide compounds, leucouramine compounds, rhodamine lactam compounds, There are various compounds such as a triphenylmethane-based compound, a triazene-based compound, a spiropyran-based compound, and a fluorene-based compound. Specific examples of the phthalides are described in U.S. Reissue Patent No. 23,024, U.S. Patent Nos. 3,491,111 and 3,491,112,
Nos. 3,491,116 and 3,509,17
No. 4, specific examples of fluorans are described in US Pat.
No. 24,107, No. 3,627,787, No. 3,
Nos. 641,011, 3,462,828, 3,681,390, 3,920,510, 3,959,571, and specific examples of spirodipyrans are described in US Pat. No. 3,971,808, pyridine and pyrazine compounds are disclosed in U.S. Pat.
No. 5,424, No. 3,853,869, No. 4,2
No. 46,318, and specific examples of fluorene-based compounds are described in Japanese Patent Application No. 61-240989.

Of these, black-colored 2-arylamino-3-H, halogen or alkyl-6-substituted aminofluorans are particularly effective. Specific examples include, for example, 2-anilino-3-methyl-6-diethylaminofluoran,
Anilino-3-methyl-6-N-cyclohexyl-N-
Methylaminofluoran, 2-p-chloroanilino-3
-Methyl-6-dibutylaminofluoran, 2-anilino-3-chloro-6-diethylaminofluoran, 2-
Anilino-3-methyl-6-N-ethyl-N-isoamylaminofluoran, 2-anilino-3-methyl-6
N-ethyl-N-dodecylaminofluoran, 2-o-
Chloroanilino-6-dibutylaminofluoran, 2-
Anilino-3-pentadecyl-6-diethylaminofluoran, 2-anilino-3-methyl-6-dibutylaminofluoran, 2-o-toluidino-3-methyl-6
Diisopropylaminofluoran, 2-anilino-3-
Methyl-6-N-isobutyl-N-ethylaminofluoran, 2-anilino-3-methyl-6-N-ethyl-N
-Tetrahydrofurfurylaminofluoran, 2-anilino-3-chloro-6-N-ethyl-N-isoamylaminofluoran, 2-anilino-3-methyl-6-N-
Methyl-N-γ-ethoxypropylaminofluoran,
2-anilino-3-methyl-6-N-ethyl-N-γ-
Ethoxypropylaminofluoran, 2-anilino-3
-Methyl-6-N-ethyl-N-γ-propoxypropylaminofluoran, 2-anilino-3-methyl-6
N-methyl-N-propylaminofluoran and the like.

A sensitizer is added in addition to the electron-donating colorless dye and the electron-accepting compound. Examples of sensitizers are disclosed in
Compounds disclosed in JP-A-8-57989, JP-A-58-87094, JP-A-63-39375 and the like can be mentioned. Aromatic ethers (especially benzyl ethers, di (substituted phenoxy) alkanes, diphenyl ethers, particularly preferably 2-benzyloxynaphthalene;
1,2-di (3-methylphenoxy) ethane, 4-biphenyl-p-tolyl ether), aromatic esters (particularly dibenzyl oxalate derivatives, particularly preferably di (p-methylbenzyl oxalate)), Biphenyl derivatives (especially parabenzylbiphenyl, metaterphenyl) or aliphatic amides, ureas or aromatic amides or ureas are representative. The sensitizer is preferably used in an amount of 50 to 800% by weight, more preferably 100 to 500% by weight of the colorless electron-donating dye. Sensitizer, in combination with the use of two or more. Particularly, it is preferable to use an aliphatic amide in combination with the aromatic compound. Preferred examples of the aliphatic amide include those represented by the general formula (IV) .

[0019]

Embedded image

[0020]

[0021]

In the above formula, R ₈ represents an alkyl group having 12 to 24 carbon atoms or an alkenyl group having 12 to 24 carbon atoms,
R ₉ represents a hydrogen atom, an alkyl group or a methylol group having 1 to 24 carbon atoms.

Specific examples include stearic acid amide, palmitic acid amide, oleic acid amide and the like . In addition, N-substituted amide compounds such as methylol stearamide and ethylenebisstearic acid amide are also included.
The amount of the amide compound or urea compound to be added is preferably 1 to 100% by weight based on the aromatic compound. More preferably, it is 2 to 50% by weight.

Next, a method for producing a typical thermosensitive coloring layer of the present invention will be described. Electron donating colorless dye, electron accepting compound,
The sensitizer is dispersed to several microns or less using a ball mill, a sand mill or the like together with an aqueous solution of a water-soluble polymer such as polyvinyl alcohol. The sensitizer is an electron-donating colorless dye,
In addition to one or both of the electron accepting compounds, they may be dispersed at the same time, or in some cases, may be prepared in advance by preparing a eutectic with an electron donating colorless dye or an electron accepting compound. These dispersions are mixed after dispersion, and if necessary, a pigment, a surfactant, a binder, a metal soap, a wax,
An antioxidant, an ultraviolet absorber and the like are added to make a heat-sensitive coating liquid. The resulting heat-sensitive coating liquid is a high quality paper, a high quality paper having an undercoat layer,
After being applied and dried on synthetic paper, plastic film, etc.,
The calendering treatment imparts smoothness to the intended heat-sensitive recording material. In this case, it is particularly preferable to use a support having a smoothness specified by JIS-8119 of 500 seconds or more, particularly 800 seconds or more, from the viewpoint of dot reproducibility. In order to obtain a support having a smoothness of 500 seconds or more, (1) use a high-smoothness material such as synthetic paper or plastic film. (2) Provide an undercoat layer containing a pigment as a main component on the support. And (3) using a super calender to increase the smoothness of the support.

The binder used in the present invention includes:
Compounds that dissolve in water at 25 ° C. in an amount of 5% by weight or more are preferable, and specifically, polyvinyl alcohol (including modified polyvinyl alcohol such as carboxy-modified, acetoacetyl-modified, itaconic-acid-modified, maleic-acid-modified, and silica-modified). , Methylcellulose, carboxymethylcellulose, starches (including modified starch), gelatin, gum arabic, casein, styrene-maleic anhydride copolymer hydrolysate, polyacrylamide, vinyl acetate-polyacrylic acid copolymer saponified product, etc. Is raised. These binders are used not only at the time of dispersion but also for the purpose of improving the strength of the coating film.
Latex binders of synthetic polymers such as butadiene copolymer, vinyl acetate copolymer, acrylonitrile / butadiene copolymer, methyl acrylate / butadiene copolymer, and polyvinylidene chloride can also be used in combination. If necessary, a crosslinking agent for an appropriate binder may be added according to the type of the binder.

Examples of the pigment used in the present invention include calcium carbonate, barium sulfate, lithopone, wax, kaolin, silica, and amorphous silica. As metal soap, higher fatty acid metal salt is used, zinc stearate,
Calcium stearate, aluminum stearate and the like are used. Further, a surfactant, an antistatic agent, an ultraviolet absorber, an antifoaming agent, a conductive agent, a fluorescent dye, a coloring dye, and the like may be added as necessary. The applied heat-sensitive recording material is dried, subjected to a treatment such as a calender, and provided for use. Further, a protective layer may be provided on the thermosensitive coloring layer as needed. As the protective layer, any known protective layer can be used as the protective layer of the heat-sensitive recording material.
Further, if necessary, a back coat layer may be provided on the surface of the support of the thermosensitive recording material opposite to the thermosensitive coloring layer. As the back coat layer, any of those known as a back coat layer of a thermosensitive recording material can be used.
Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to the following Examples.

[0027]

EXAMPLES Reference Example 1 As an electron donating colorless dye,
2-anilino-3-methyl-6-dibutylaminofluoran, zinc N-benzoylanthranilate as an electron accepting compound, di (p-methylbenzyl) oxalate as a sensitizer, 20 g each of 100 g of 5% polyvinyl chloride The mixture was dispersed with an alcohol (Kuraray PVA-105) aqueous solution in a ball mill all day and night to reduce the average particle size to 1.5 μm or less to obtain each dispersion. In addition, 80 g of calcium carbonate
Was dispersed with a homogenizer together with 160 g of a 0.5% sodium hexametaphosphate solution to obtain a pigment dispersion. Each of the dispersions prepared as described above was used for 5 g of an electron-donating colorless dye dispersion, 10 g of an electron-accepting compound dispersion, and di (oxalate)
(Methylbenzyl) ester dispersion (10 g) and calcium carbonate dispersion (5 g) were mixed together, and 3 g of a 21% zinc stearate emulsion was further added to obtain a heat-sensitive coating liquid. This thermosensitive coloring layer coating solution was coated on a high-quality paper having a basis weight of 50 g / m ² by using a wire bar and dried weight of the coating layer was 5 g / m 2.
² and dried at 50 ° C. for 1 minute to obtain a thermosensitive recording paper.

[0028]

[0029]

[0030]

[0031]

[0032]

[0033]

[0034]

[0035]

[0036]

[0037]

[0038]

[0039]

Example 1 In the preparation of Reference Example 1 , zinc N- (phenoxyacetyl) anthranilate was used instead of zinc zinc N-benzoylanthranilate, and a 21% stearamide dispersion ( A heat-sensitive recording paper was obtained in the same manner except that 2 g of High Micron G270 (manufactured by Chukyo Yushi Co., Ltd.) was added to prepare a heat-sensitive coating solution.

Example 2 In the preparation of Reference Example 1 , zinc N- (phenoxyacetyl) anthranilate and di (p-methylbenzyl) oxalate were used instead of using zinc N-benzoylanthranilate. Instead of using 2-benzyloxynaphthalene, the same heat-sensitive coating liquid was prepared except that 2 g of a 22% methylol stearamide dispersion (Hydrin D-130 manufactured by Chukyo Yushi Co., Ltd.) was added. Thermal recording paper was obtained by the method.

[0042]

[0043]

[0044]

Comparative Example 1 A thermosensitive recording paper was obtained in the same manner as in Example 1, except that bisphenol A was used in place of zinc N-benzoylanthranilate to prepare a thermosensitive coating solution. .

(Comparative Example 2) A heat-sensitive coating liquid was prepared in the same manner as in Example 1, except that benzyl 4-hydroxybenzoate was used to prepare a heat-sensitive coating solution instead of using zinc N-benzoylanthranilate. Recording paper was obtained.

(Comparative Example 3) Instead of using the zinc N-benzoylanthranilate of Example 1, 4- (4-
A heat-sensitive recording paper was obtained in the same manner except that a heat-sensitive coating solution was prepared using isopropoxyphenylsulfonyl) phenol.

The heat-sensitive recording paper obtained as described above is
The surface was treated with a calender, and the smoothness was adjusted to a Beck smoothness of 300 ± 50 seconds to obtain a heat-sensitive recording material. The evaluation of the thermal recording paper was performed as follows. (1) Color density is 30 mJ / printing energy using a Kyocera printing tester.
It was printed in mm2 and the color density was measured with a Macbeth densitometer.
The higher the value, the higher the sensitivity of the thermal recording paper. (2)
In the chemical resistance test, ethanol and a plasticizer (dioctyl phthalate) were each impregnated into a filter paper and superimposed on the coloring surface of the recording paper obtained by the above method, and the fog on the white background and the decoloration (discoloration) of the colored portion were obtained. Was evaluated. Table 1 shows the above results.

[0049]

[Table 1]

[0050]

[0051]

As can be seen from the results shown in Table 1, the recording material of the present invention has high sensitivity, does not cause fogging or decoloration of the colored portion due to chemicals, and has extremely excellent performance. I understand.

Continuation of the front page (56) References JP-A-4-211989 (JP, A) JP-A-4-122683 (JP, A) JP-A-54-111905 (JP, A) JP-A-7-126232 (JP) JP-A-6-270549 (JP, A) JP-A-6-155925 (JP, A) JP-A-6-64321 (JP, A) JP-A-7-179411 (JP, A) 7-214916 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B41M 5/28-5/34

Claims (3)

(57) [Claims] 1. A thermosensitive recording material comprising a support and a thermosensitive coloring layer containing an electron-donating colorless dye and an electron-accepting compound, wherein (1) the thermosensitive coloring layer is represented by the following general formula (I). N-substituted anthranilic acid derivatives or metal salts thereof, (2) di (p-methylbenzyl) oxalate,
Benzyloxynaphthalene, parabenzylbiphenyl,
Tatterphenyl, 4-biphenyl-p-tolylate
From 1,2-di (3-methylphenoxy) ethane.
And (3) an aliphatic amide compound selected from the group consisting of
Heat-sensitive recording material characterized by containing an object. Embedded image In the above formula, R ₁ represents a hydrogen atom, an alkyl group or an aryl group, R ₂ represents an alkyl group, a cycloalkyl group, an aryl group, an alkylamino group, an alkyloxy group, an aryloxy group or an arylamino group; An atom or a sulfur atom, M represents an n-valent metal atom, and n represents an integer. 2. The thermosensitive recording material according to claim 1, wherein the thermosensitive coloring layer further contains zinc oxide . 3. The colorless electron-donating dye is 2-anilino-3.
-Methyl-6-diethylaminofluoran, 2-anili
No-3-methyl-6-N-cyclohexyl-N-methyl
Aminofluorane, 2-p-chloroanilino-3-methyl
Ru-6-dibutylaminofluoran, 2-anilino-3
-Chloro-6-diethylaminofluoran, 2-anili
No-3-methyl-6-N-ethyl-N-isoamylami
Nofluoran, 2-anilino-3-methyl-6-N-e
Tyl-N-dodecylaminofluoran, 2-o-chloro
Anilino-6-dibutylaminofluoran, 2-anili
No-3-pentadecyl-6-diethylaminofluora
2-anilino-3-methyl-6-dibutylaminophen
Luoran, 2-o-toluidino-3-methyl-6-dii
Sopropylaminofluoran, 2-anilino-3-methyl
Le -6-N-isobutylene chill -N- ethylamino fluorous
, 2-anilino-3-methyl-6-N-ethyl-N-
Tetrahydrofurfurylaminofluoran, 2-anili
No-3-chloro-6-N-ethyl-N-isoamylamido
Nofluoran, 2-anilino-3-methyl-6-N-me
Chill-N-γ-ethoxypropylaminofluoran, 2
-Anilino-3-methyl-6-N-ethyl-N-γ-e
Toxipropylaminofluoran, 2-anilino-3-
Methyl-6-N-ethyl-N-γ-propoxypropyl
Aminofluoran or 2-anilino-3-methyl-6
Be N-methyl-N-propylaminofluoran
The heat-sensitive recording material according to claim 1, wherein: