JPH0336031B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a reversible thermosensitive recording material, and in particular, it is possible to obtain a record of a positive image or a negative image by partially applying cold or heat using the hysteresis property of a coloring component. The present invention relates to a heat-sensitive recording material that can be maintained by keeping it within a predetermined temperature range, can be easily erased by exposing it to high or low temperatures when unnecessary, and can be used repeatedly. As a conventional reversible thermosensitive recording material of this kind,
Materials that utilize the thermochromic properties of metal complexes such as Ag ₂ HgI ₄ or Cu ₂ HgI ₄ , and recently proposed matrix materials made of thermoplastic resins that repeatedly become transparent and cloudy upon application of heat. Heat-sensitive image display material consisting of an organic low-molecular substance dispersed in the matrix material (Japanese Patent Application Laid-Open No. 57-89992, 3)
can be given. However, these thermal display materials have (1) low contrast between the recording part and the base;
There are drawbacks such as (2) the inability to set a desired recording temperature, and (3) the inability to freely select colors. An object of the present invention is to provide a reversible thermosensitive recording material that eliminates the above-mentioned drawbacks. The reversible thermosensitive recording material of the present invention includes (a) an electron-donating color-forming organic compound, (b) a compound having a phenolic hydroxyl group and a metal salt thereof, an aromatic carboxylic acid,
C2-C5 aliphatic carboxylic acids, carboxylic acid metal salts, acidic phosphoric acid esters and their metal salts,
Compounds selected from 1,2,3-triazole and derivatives thereof, and (c) alcohols, esters, ketones, ethers, acid amides, aliphatic carboxylic acids having 6 or more carbon atoms, thiols, and sulfides. , disulfides, sulfoxides, and sulfones are used as the coloring component. It exhibits a hysteresis phenomenon in response to changes in temperature (displayed on the horizontal axis) and repeats coloring and discoloration. Here, A is the lowest temperature at which the color completely disappears.
Point B indicates the concentration at T ₃ , and B is the point indicating the concentration at the maximum temperature T ₁ that reaches a fully colored state, and at the holding temperature T ₂ , two phases of point C in the colored state and point D in the decolored state are formed. They are in a state of coexistence. this
The temperature range near T ₂ , ie, the temperature range where the colored state and the decolored state can coexist, is the temperature range where records can be maintained. The length of the line segment CD is a measure of the contrast between the recording and the background, and the length of the line segment EF passing through the midpoint of the line segment CD is the temperature range that indicates the degree of hysteresis. , record keeping is easy. According to experiments conducted by the present inventors, the temperature range needs to be 3° C. or more from the viewpoint of practical record retention, and preferably 8° C. or more. Next, the constituent components of the thermochromic material will be described. The electron-donating color-forming organic compounds of component (a) include diaryl phthalides, polyaryl carbinols, leucoauramines, acylouramines, arylauramines, rhodamine B lactams, indolines, and spiropyrans. There are fluorans, fluorans, etc. Examples of these compounds are shown below. Crystal violet lactone, malachite green lactone, Michler hydrol, crystal violet carbinol, malachite green carbinol, N-(2,3-dichlorophenyl)leucouramine, N-benzoyluramine, rhodamine B lactam, N-acetyl auramine, N-phenyl auramine, 2-(phenyliminoethanedylidene)-3,3-dimethylindoline, N-3,3-trimethylindolinobenzospiropyran, 8-methoxy-N-3・3-
Trimethylindolinobenzospiropyran, 3-
Diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-7-methoxyfluorane, 3-diethylamino-6-benzyloxyfluorane, 1,2-benz-6-diethylaminofluorane, 3,6-di- P-toluidino-
4,5-dimethylfluoran-phenylhydrazide-γ-lactam, 3-amino-5-methylfluoran, 2-methyl-3-amino-6-methyl-
7-methylfluorane, 2,3-butylene-6-
Di-n-butylaminofluorane, 3-diethylamino-7-anilinofluorane, 3-diethylamino-7-(para-toluidino)-fluorane, 7
-acetamino-3-diethylaminofluorane, 2-bromo-6-cyclohexylaminofluorane, 2,7-dichloro-3-methyl-6-n
-butylaminofluorane, etc. Next, component (b) will be described. As a compound having a phenolic hydroxyl group,
There are monophenols and polyphenols,
Furthermore, as a substituent, an alkyl group, an aryl group,
Examples include acyl groups, alkoxycarbonyl groups, and halogens. Examples of these compounds are shown below. Tertiary-butylphenol, nonylphenol, dodecylphenol, styrene-tated phenol, 2,2-methylenebis-(4-methyl-6-tertiary-butylphenol), α-
Naphthol, β-naphthol, hydroquinone monomethyl ether, guaiacol, eugenol, p-chlorophenol, P-bromophenol, o-chlorophenol, o-bromophenol, o-phenylphenol, P-phenylphenol, P-(P -chlorophenyl)-phenol, o-(o-chlorophenyl)-phenol, P
-Methyl oxybenzoate, ethyl P-oxybenzoate, propyl P-oxybenzoate, butyl P-oxybenzoate, octyl P-oxybenzoate,
Dodecyl P-oxybenzoate, 3-isopropylcatechol, P-tert-butylcatechol, 4,4'-methylenediphenol, 4,4'-thio-bis-(6-tert-butyl-3- methylphenol), 1,1-bis-(4-hydroxyphenyl)-cyclohexane, 4,4'-butylidene-bis-(6-tert-butyl-3-methylphenol), bisphenol A, bisphenol S, 1,2-dioxynaphthalene, 2,3-
Dioxynaphthalene, chlorcatechol, bromocatechol, 2,4-dihydroxybenzophenone, phenolphthalein, o-cresolphthalein, methyl protocatechuate, ethyl protocatechuate, propyl protocatechuate,
Octyl protocatechuate, dodecyl protocatechuate, 2,4,6-trioxymethylbenzene, 2,3,4-trioxyethylbenzene,
Methyl gallate, ethyl gallate, propyl gallate, butyl gallate, hexyl gallate, octyl gallate, dodecyl gallate, cetyl gallate, stearyl gallate, 2,3,5-trioxynaphthalene, tannic acid, phenol There are resins, etc. Examples of metal salts of compounds having a phenolic hydroxyl group include sodium, potassium, lithium, calcium, zinc, zirconium, aluminum, magnesium, nickel, cobalt, tin, copper, iron, vanadium, titanium, There are metal salts of lead, molybdenum, and other metals. Aromatic carboxylic acids and aliphatic carboxylic acids having 2 to 5 carbon atoms include maleic acid, fumaric acid, benzoic acid, toluic acid, P-tert-butylbenzoic acid, chlorobenzoic acid, bromobenzoic acid, and ethoxybenzoic acid. acids, gallic acid, naphthoic acid, phthalic acid,
naphthalene dicarboxylic acid, acetic acid, propionic acid,
Examples include butyric acid and valeric acid. Examples of carboxylic acid metal salts include metal salts of monocarboxylic acids to polycarboxylic acids. Examples of these compounds are shown below. Acetic acid, propionic acid, butyric acid, caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, isostearic acid, behenic acid, crotonic acid, oleic acid, elaidic acid, linoleic acid, linolenic acid, monochlor Acetic acid, monobromoacetic acid, monofluoroacetic acid, glycolic acid, hydroxypropionic acid, hydroxybutyric acid, ricinoleic acid, 12-hydroxystearic acid, lactic acid, pyruvic acid, oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, malic acid, Tartaric acid, citrusic acid, maleic acid, fumaric acid, naphthenic acid, benzoic acid, toluic acid, phenylacetic acid, P-tert-butylbenzoic acid, cinnamic acid,
Chlorbenzoic acid, bromobenzoic acid, ethoxybenzoic acid, mandelic acid, protocatechuic acid, vanillic acid, resorcinic acid, dioxybenzoic acid, dioxychlorobenzoic acid, gallic acid, naphthoic acid, hydroxynaphthoic acid, phthalic acid, monophthalic acid Sodium, potassium, lithium, calcium, zinc, zirconium, aluminum, magnesium, nickel, cobalt, tin, copper, iron, vanadium, titanium, such as ethyl ester, naphthalene dicarboxylic acid, naphthalene dicarboxylic acid monomethyl ester, trimellitic acid, pyromellitic acid, etc.
There are metal salts of metals such as lead and molybdenum. Examples of the acidic phosphate ester compound include ester groups such as alkyl groups, branched alkyl groups, alkenyl groups, alkynyl groups, cycloalkyl groups, aryl groups, and derivatives thereof. Acidic phosphoric acid ester compounds include monoesters and diesters, and may also be mixtures thereof. In the following compounds, the mixture of monoester and diester is called acid phosphate. Examples of acidic phosphoric acid ester compounds are shown below. Methyl acid phosphate, ethyl acid phosphate, n-propyl acid phosphate, n-butyl acid phosphate, 2-ethylhexyl acid phosphate, n-octyl acid phosphate, isodecyl acid phosphate , n-decyl acid phosphate, lauryl acid phosphate, myristyl acid phosphate, cetyl acid phosphate,
stearyl acid phosphate, docosyl acid phosphate, oleyl acid phosphate, 2-chloroethyl acid phosphate,
2,3-dipromo-2,3-dichloropropyl acid phosphate, dichloropropyl acid phosphate, cyclohexyl acid phosphate, phenyl acid phosphate, o-tolyl acid phosphate, 2,3-xyl acid phosphate Ruacid phosphate, P-cumenyl acid phosphate, mesityl acid phosphate, 1-naphthyl acid phosphate, 2-naphthyl acid phosphate, 1-anthryl acid phosphate, benzyl acid phosphate ate, phenethyl acid phosphate, styryl acid phosphate, cinnamyl acid phosphate, trityl acid phosphate, phenyl methyl phosphate, phenylethyl phosphate, phenyl n-propyl phosphate, phenyl n-butyl Phosphate, phenyl n-octyl phosphate, phenyl lauryl phosphate, phenyl cyclohexyl phosphate, phenyl (2,3-xylyl) phosphate, cyclohexyl stearyl phosphate, cyclohexyl cetyl phosphate, dimethyl phosphate,
Diethyl phosphate, di-n-propyl phosphate, di-n-butyl phosphate, di-n-hexyl phosphate, di(2-ethylhexyl) phosphate, di-n-decyl phosphate, dilauryl phosphate, dimyristyl phosphate, Dicetyl phosphate, distearyl phosphate, dibehenyl phosphate, diphenyl phosphate, dicyclohexyl phosphate, di-
Tolyl phosphate, bis(diphenylmethyl)
Examples include phosphate, bis(triphenylmethyl) phosphate, di(2,3-xylyl) phosphate, dibenzyl phosphate, di(1-naphthyl) phosphate, and the like. As metal salts of acidic phosphate ester compounds,
The above compounds sodium, potassium, lithium,
Calcium, zinc, zirconium, aluminum, magnesium, nickel, cobalt, tin,
There are metal salts of metals such as copper, iron, vanadium, titanium, lead, and molybdenum. Examples of triazole compounds include 1,2,3-triazole, 4(5)-hydroxy-1,2,3-triazole, 5(6)-methyl-1,2,3-benzotriazole, 5-chloro-1, 2,3-benzotriazole, 7-nitro-1,2,3-benzotriazole, 4-benzoylamino-1,2,
3-benzotriazole, 4-hydroxy-1,
2,3-benzotriazole, naphtho-1,2,
3-triazole, 5,5'-bis(1,2,3-
benzotriazole), 1,2,3-benzotriazole-4-sulfooctylamide, and the like. Next, component (c) will be described. Alcohols include monohydric alcohols, polyhydric alcohols, and derivatives thereof. Examples of these compounds are shown below. n-octyl alcohol, n-nonyl alcohol, n-decyl alcohol, n-lauryl alcohol, n-myristyl alcohol, n-cetyl alcohol, n-stearyl alcohol, n-icosyl alcohol, n-docosyl alcohol, n-
-mericyl alcohol, isocetyl alcohol,
Isostearyl alcohol, isodocosyl alcohol, oleyl alcohol, cyclohexanol, cyclopentanol, benzyl alcohol,
Cinnamyl alcohol, ethylene glycol, diethylene glycol, triethylene glycol,
Examples include polyethylene glycol, propylene glycol, butylene glycol, hexylene glycol, cyclohexane-1,4-diol, trimethylolpropane, 1,2,6-hexanetriol, pentaerythritol, sorbitol, mannitol, and the like. Examples of compounds as esters are shown below. Amyl acetate, octyl acetate, butyl propionate, octyl propionate, phenyl propionate, ethyl caproate, amyl caproate, ethyl caprylate, amyl caprate, ethyl caprate, amyl caprate, octyl caprate,
Methyl laurate, ethyl laurate, butyl laurate, hexyl laurate, octyl laurate, dodecyl laurate, myristyl laurate, cetyl laurate, stearyl laurate,
Methyl myristate, ethyl myristate, butyl myristate, hexyl myristate, octyl myristate, lauryl myristate, myristyl myristate, cetyl myristate, stearyl myristate, methyl palmitate, ethyl palmitate, butyl palmitate, palmitic acid Hexyl, octyl palmitate, lauryl palmitate, myristyl palmitate, cetyl palmitate, stearyl palmitate, methyl stearate, ethyl stearate, butyl stearate, hexyl stearate, octyl stearate, lauryl stearate, myristyl stearate, Cetyl stearate, stearyl stearate, methyl behenate, ethyl behenate, propyl behenate, butyl behenate, ethyl benzoate, butyl benzoate, amyl benzoate, phenyl benzoate, ethyl acetoacetate, methyl oleate, oleic acid Butyl, butyl acrylate, diethyl oxalate, dibutyl oxalate, diethyl malonate, dibutyl malonate, dibutyl tartrate, dibutyl sebatate, dimethyl sebatate, dimethyl phthalate, dibutyl phthalate, dioctyl phthalate, dibutyl fumarate, malein Examples include diethyl acid, dibutyl maleate, triethyl citrate, 12-hydroxystearic acid triglyceride, castor oil, dioxystearic acid methyl ester, and 12-hydroxystearic acid methyl ester. The following compounds are exemplified as ketones. Diethyl ketone, ethyl butyl ketone, methylhexyl ketone, mesityl oxide, cyclohexanone, methylcyclohexanone, acetophenone, propiophenone, benzophenone, 2.4
- Pentanedione, acetonyl acetone, diacetone alcohol, ketone wax, etc. The following compounds are exemplified as ethers. Butyl ether, hexyl ether, diisopropyl benzyl ether, diphenyl ether,
Examples include dioxane, ethylene glycol dibutyl ether, diethylene glycol dibutyl ether, ethylene glycol diethyl ether, diethylene glycol diethyl ether, ethylene glycol diphenyl ether, and ethylene glycol monophenyl ether. Examples of acid amide compounds are shown below. 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 anilide, caprylic acid anilide, capric acid anilide, lauric acid anilide 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-methylamide
-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, myristic acid N-octylamide, palmitic acid N-octylamide, stearic acid N-octylamide, oleic acid N-octylamide, lauric acid N-dodecylamide, myristic acid acid N-
dodecylamide, palmitic acid N-dodecylamide, stearic acid N-dodecylamide, oleic acid N-dodecylamide, distearic acid amide,
Dipalmitic acid amide, Dimyristic acid amide,
dilauric acid amide, dioleic acid amide, tristearic acid amide, tripalmitic acid amide,
trimyristic acid amide, trilauric acid amide, trioleic acid amide, succinic acid amide, adipic acid amide, glutaric acid amide, malonic acid amide, azelaic acid amide, maleic acid amide,
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-methylamide
-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-butylamide
-octylamide, adipic acid N-dodecylamide, etc. Examples of aliphatic carbon groups having 6 or more carbon atoms include caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachic acid, behenic acid, lignoceric acid, cerotic acid, montanic acid, and melisic acid. , isomyristic acid, isopalmitic acid, isostearic acid,
Oleic acid, elaidic acid, linoleic acid, linolenic acid, eleostearic acid, arachidonic acid, 2-
Oxylauric acid, 2-oxymyristic acid, 2
-oxypalmitic acid, 2-oxystearic acid, 3-oxystearic acid, 12-hydroxystearic acid, ricinoleic acid, 2-bromurauric acid, 2-bromyristic acid, 2-brompalmitic acid, 2-bromostearic acid, 18-bromstearic acid, 2-chlorostearic acid, 18-chlorostearic acid, dioxypalmitic acid, dioxystearic acid, 3-ethyl-3-lauryl-3
Oxypropionic acid, 2-methyl-3-oxystearic acid, 2-ketostearic acid, 2-ketopalmitic acid, azelaic acid monoethyl ester,
Azelaic acid monobutyl ester, azelaic acid monooctyl ester, sebacic acid monoethyl ester, sebacic acid monobutyl ester, sebacic acid monooctyl ester, sebacic acid monolauryl ester, 1,12-dodecamethylenedicarboxylic acid, 1,14-tetra decamethylene dicarboxylic acid, 1,16-hexadecamethylene dicarboxylic acid,
There are dimer acids, etc. Examples of thiol compounds are shown below. n-decyl mercaptan, n-dodecyl mercaptan, n-myristyl mercaptan, n-cetyl mercaptan, n-stearyl mercaptan,
Examples include iso-dodecyl mercaptan, iso-myristyl mercaptan, iso-cetyl mercaptan, and dodecylbenzyl mercaptan. Examples of sulfide compounds are shown below. Di-n-octyl sulfide, di-n-nonyl sulfide, di-n-decyl sulfide, di-n
-Dodecyl sulfide, di-n-myristyl sulfide, di-n-cetyl sulfide, di-n-stearyl sulfide, di-tert-dodecyl sulfide, octyldodecyl sulfide, diphenyl sulfide , dibenzyl sulfide, ditolyl sulfide, diethyl phenyl sulfide, 4.4
-Dichlorodiphenyl sulfide, dilaurylthiodipropionate, distearylthiodipropionate, tetra(laurylthiopropionic acid)
Examples include pentaerythritol ester, etra(stearylthiopropionic acid) pentaerythritol, and the like. Examples of disulfide compounds are shown below. Di-n-decyl disulfide, di-n-dodecyl disulfide, di-n-myristyl disulfide, di-n-cetyl disulfide, di-n-stearyl disulfide, diphenyl disulfide ,
Examples include dibenzyl disulfide, ditolyl disulfide, dinaphthyl disulfide, and 4,4-dichlorodiphenyl disulfide. Examples of sulfoxide compounds are shown below. Examples include dimethyl sulfoxide, diethyl sulfoxide, tetramethylene sulfoxide, diphenyl sulfoxide, and dibenzyl sulfoxide. Examples of sulfone compounds are shown below. Examples include diethyl sulfone, dibutyl sulfone, methyl phenyl sulfone, diphenyl sulfone, ditolyl sulfone, dibutyl phenyl sulfone, dibenzyl sulfone, 4,4-dichlorodiphenyl sulfone, and the like. The above three components (a), (b) and (c) are 1:0.1~50:1~
A thermochromic material can be obtained by mixing and heating melting at a weight ratio of 800 to obtain a homogeneous compatible solution. Here, component (A) determines the color of the thermochromic material when it develops color, component (B) reacts with component (A) to cause reversible coloration, and component (C) serves to control temperature and sensitivity to the reaction. The degree of hysteresis characteristic of coloring and decoloring of these thermochromic materials varies depending on each component and the ratio of their amounts, but the component (c) and its amount are the dominant factors. Generally, the color change temperature range is near the melting point of component (c), and therefore, by appropriately combining compounds with different melting points, a thermochromic material exhibiting a desired color change temperature range and retention temperature range can be obtained. As mentioned above, these thermochromic materials exhibit a hysteresis phenomenon and repeatedly change color and discolor in response to temperature changes, as shown in the graph of Figure 1, but they contain acidic phosphate esters or their metals as the component (b). If salt is used, the graph will be rotated 180 degrees around the CD line. That is, it becomes a colored state on the high temperature side, and becomes a discolored state on the low temperature side. The reversible thermosensitive recording material of the present invention can be produced by applying the thermochromic material to the surface of a sheet substrate such as paper, plastic film, cloth or metal foil sheet by heating and melting it, or by applying a well-known encapsulation method such as core cell coating. Applying a coating composition in which the resulting microcapsules are dispersed in a vehicle consisting of a resin solution, a resin emulsion, or a mixture thereof. It can be obtained by The present invention will be described below with reference to Examples. Example 1 4 g of crystal violet lactone, 20 g of bisphenol A, and 100 g of myristyl alcohol were homogenized by heating and melted, and the resultant recording sheet was uniformly applied to high-quality paper, and the resulting recording sheet was heated to 45°C to make it white. When a rubber letterpress cooled to 15°C was pressed onto a recording sheet at a room temperature of 27°C, a blue positive image was clearly displayed, and the image was maintained even after being left at a room temperature of 25 to 30°C for 24 hours. was. Then this sheet
When heated uniformly to 40°C, the image was erased and a uniform white surface appeared. Each time this operation was repeated, image formation and erasure were performed repeatedly. Example 2 PSD-P (Fluorane leuco dye, Nisso Kako Co., Ltd.
Co., Ltd.), 16 g of bisphenol A zinc salt, 50 g of cyclododecanol, and 50 g of cetyl alcohol were heated and melted to homogenize and uniformly applied to coated paper.
A recording sheet obtained by laminating a 20 μm polypropylene film was cooled to 10° C. so that the entire surface turned pink, and then left at 25° C. When characters were written on this sheet with a thermal pen whose tip was set to approximately 50°C, a negative image with high contrast of white spots on a pink background was obtained, and the image was retained for any retention time. was completed. Then heat the sheet at 50℃
When heated to a temperature of 100°C to completely turn white, the material was left to cool to 25°C, and when an image was drawn with a cold pen with the nib set at approximately 10°C, a positive image with a high contrast of pink on a white background was obtained. Images could be retained for any retention time. In this way, both positive and negative images could be displayed and erased as many times as desired. The performance characteristics of the recording materials of Examples 3 to 8, such as the components used, composition ratio, recording temperature, holding temperature, erasing temperature, and coloration are shown in Table 1 below. In both cases, the manufacturing method was the same as in Example 1.

【table】

[Table] Example 9 6 g of onedye Black (fluoran-based leuco dye, manufactured by Yamamoto Kagakusei Co., Ltd.), 15 g of bisphenol S, 60 g of stearyl alcohol, and 40 g of trimyristin were homogenized by heating and melting, followed by the well-known coacelvation method. 80 g of microcapsules containing a thermochromic material obtained by encapsulation were mixed with a separately prepared ethylene-vinyl acetate copolymer emulsion (Polysol
EVA P-8 (manufactured by Showa Kobunshi Co., Ltd.) 200g, sodium alginate 40g, and water 80g are dispersed in a vehicle, and this is uniformly applied to a 25μ polyester film, followed by lamination with a 20μ polypropylene film to form a recording material sheet. I got it. When an image was recorded on this sheet using a thermal head for heat-sensitive recording and immediately held on a heat-retaining panel kept at 40°C, a black-and-white negative image with high contrast was obtained and could be held for any length of time. Next, from the insulation panel
After passing through a heating section at 60℃ and a cooling section at 10℃, a reversed image was printed with a thermal head and held on a heat insulation panel, resulting in a high-contrast black-and-white positive image that could be kept for any length of time. did it.
Image formation, holding, and erasing could be repeated many times in this cycle. Example 10 PSD-T-126 (fluorane-based leuco dye, manufactured by Shin Nisso Kako Co., Ltd.) 5 g, zinc benzoate 15 g, G-n
- Heat and melt 100 g of hexyl ketone to homogenize it,
200 g of styrene-maleic acid copolymer (Scripset 540, manufactured by Monsanto, USA) prepared separately from 80 g of microcapsules containing a thermochromic material obtained by encapsulation by the well-known coacervation method;
It was dispersed in a vehicle consisting of 20 g of 28% ammonia water and 40 g of water, and coated on high-quality paper to obtain a recording material sheet. After heating this sheet to 30℃ to make it completely white, I printed it with a cold pen with the nib set at 0℃ at a holding temperature range of 10 to 15℃, resulting in a high contrast green positive on a white background. The image is obtained,
It could be held for any length of time. Next, when the sheet was heated again to 30°C, the entire sheet became white and could be recorded and erased many times. As explained above, the reversible thermosensitive recording material of the present invention has the advantage that by appropriately selecting the composition of the thermochromic material used, it is possible to obtain the desired color and recording, retention, and erasing temperatures compared to conventional recording materials of the same type. This is a feature not seen in In particular, recording materials that have a holding temperature range in the room temperature range are of high utility value. Also, regarding the contrast between the recording and the background, pure white was set to 10,
When expressed as the difference in brightness between the recording and the base (corresponding to the line segment CD and length of the graph in Figure 1), the difference in brightness between the recording material and the base (corresponding to the line segment CD and length in the graph in _{Figure 1 )} is as follows: ), the contrast was approximately 1.0 to 1.1, whereas the recording material of the present invention exhibited high contrasts of 6.5 to 7.0 between white background and black background, approximately 5.0 between white background and blue background, and approximately 4.0 between white background and red background. The reversible heat-sensitive recording material of the present invention can be used not only as a heat-sensitive recording material capable of repeated recording and erasing, but also as a heat-sensitive display material for thermal displays. In this case, as a special method, a display material of three colors is used, for example, in which a coating containing a thermochromic material exhibiting one of the three primary colors is applied to a separate film.
When used in a thermal display device such as that disclosed in Japanese Patent No. 53-133180, it is also possible to display a reversible color image with three color separation. Further, a combination of a cold pen and a thermal eraser or a thermal pen and a cold eraser can be used as a writing board. It is also used as a toy. For example, there are writing boards for baths that utilize the temperature difference between hot and cold water. It can also be used as a recording material for recording devices using laser light. In addition, you can enjoy changing the design many times by taking advantage of its inherent properties, so you can enjoy neckties, T-shirts,
It can be applied to fashion-related fields such as shirts, sweatshirts, blouses, gloves, and ski wear, and decoration-related fields such as ribbon flower wall hangings and curtains.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the hysteresis characteristic of color density change due to temperature change of the thermochromic material used in the reversible thermosensitive recording material of the present invention. The horizontal axis is the temperature, and the vertical axis is the color density.

Claims (1)

[Scope of Claims] 1 (a) Electron-donating color-forming organic compounds, (b) Compounds having phenolic hydroxyl groups and metal salts thereof;
Compounds selected from aromatic carboxylic acids, aliphatic carboxylic acids having 2 to 5 carbon atoms, carboxylic acid metal salts, acidic phosphoric acid esters and their metal salts, 1,2,3-triazole and derivatives thereof, and (iii) alcohols. , esters, ketones, ethers, acid amides, aliphatic carboxylic acids having 6 or more carbon atoms, thiols, sulfides, disulfides, and sulfonic acids as an essential component. A reversible thermosensitive recording material, which is coated on the surface of a sheet substrate with a coating composition containing as a coloring component a thermochromic material that exhibits hysteresis characteristics in a temperature range of 3° C. or more during the process of discoloration due to temperature changes. 2. The reversible thermosensitive recording material according to claim 1, wherein the coating composition is in a form in which the thermochromic material encapsulated in microcapsules is dispersed in a vehicle. 3. The reversible thermosensitive recording material according to claim 1 or 2, wherein a substantially transparent coating layer is provided on the layer of the coating composition applied to the surface of the sheet substrate.