JP3263130B2 - Reversible thermochromic 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 color material which changes color sharply and reversibly in response to a change in temperature.

[0002]

2. Description of the Related Art A reversible thermochromic material has a property of discoloring at a specified temperature.
It is used in the field of articles that require an appropriate temperature, a warning, and a dangerous temperature display, and a product that enjoys a change in color. For example, frozen foods and beverages that require refrigeration and warming, writing utensils,
It can be used for stationery such as postcards, clothing, toys, etc.

Conventionally, reversible thermochromic materials include:
A composition comprising three components of a metal complex salt crystal, a cholesteric liquid crystal, an electron-donating color former, a compound having a phenolic hydroxyl group, and a compound having an alcoholic hydroxyl group (for example, Japanese Patent Publication No. 51-44).
No. 706, Japanese Patent Publication No. 51-44707, Japanese Patent Publication No. 51-4
No. 4709), a composition comprising three components such as phthales, fluoresceins, an electron donating organic nitrogen compound, an alcohol and an acid amide (for example, JP-A-57-65772).
No. 1), a composition containing a polyhydroxy compound, an alkali metal borate and a pH-indicating dye are known.

[0004] Among these reversible thermochromic materials, those using crystals of metal complex salts are excellent in heat resistance and light resistance, and are used in some industrial applications. However, there is a drawback that the color hue is high. Cholesteric liquid crystals are used in thermometers, decorative articles, daily necessities, etc., but have disadvantages in that the discoloration temperature cannot be freely selected, are expensive, and the discoloration life is short. Compositions comprising an electron-donating color former, 2,2-bis (4-hydroxyphenyl) propane (hereinafter referred to as bisphenol A) and alcohols are widely used for stationery, toys, clothing, etc. The place to use is limited because of poor properties. Further, a composition comprising three components such as phthales or fluoresceins, an electron-donating organic nitrogen compound, an alcohol, and an acid amide has few types of coloring hues, a polyhydroxy compound, an alkali metal borate, a pH indicating dye, Has a problem that the application is limited because the discoloration temperature is high and the discoloration response takes time.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a reversible thermochromic material which has a fast response to a change in temperature, a high color density, and excellent fastness in response to a temperature change. Is to provide the material.

[0006]

Means for Solving the Problems The present inventors have conducted various studies to achieve the above object, and as a result, have found that an electron-donating color former, a certain compound, alcohols, esters, ethers, By using as a component a compound selected from ketones, carboxylic acids or acid amides, it has been found that a reversible thermochromic material having remarkably excellent performance can be obtained, and the present invention has been achieved. That is, the present invention
(A) an electron-donating color former; and (b) a general formula (I)

[0007]

Embedded image (Wherein, R _1, R ₂ represents a hydrogen atom, C ₁ -C ₃ alkyl group, a halogenated alkyl group of C ₁ -C _3, a hydroxyl group, a cyclohexyl group or a phenyl group, R _1,
When any one of R ₂ is a cyclohexyl group or a phenyl group, the other is a hydrogen atom, and R ₃ and R ₄ are a hydrogen atom,
_A C ₁ -C ₁₅ alkyl group, a C ₁ -C ₁₅ halogenated alkyl group, a hydroxyl group, a cyclohexyl group or a phenyl group, wherein two R ₁ -R ₄ are the same or different, R _{1 to} R ₄ are not simultaneously hydrogen atoms, and n is an integer of 0, 1 or 2) or at least one of the compounds represented by the general formula (II) (Formula 4) When,

[0008]

Embedded image (Wherein R ₅ represents a C ₁ -C ₁₂ alkyl group, a C ₃ -C ₁₀ cycloalkyl group, a C ₇ -C ₁₀ aralkyl group or a phenyl group, and two R _{5 s} are the same as each other. And (n is an integer of 0 or 1 or 2). (C) At least one compound selected from alcohols, esters, ethers, ketones, carboxylic acids and acid amides The present invention relates to a reversible thermochromic material containing the above three components in a microcapsule wall film.

The reversible thermochromic material of the present invention selects a color according to the type of an electron-donating color former (hereinafter referred to as a color former) (a) and obtains a compound represented by the general formula (I) or (II) ( b) to form an alcohol, an ester,
The color change temperature can be determined depending on the type of the compound (c) selected from ethers, ketones, carboxylic acids or acid amides. Since the compound of (b) has excellent solubility in (c), the selectivity of the type of the color-forming agent of (a) is widened, and (b) to (c) within a range that does not significantly affect the color change temperature. By increasing the amounts of a) and (b), it is expected that the color density and the light resistance of the color image will be improved. In addition, since the solubility of the compound (b) in water is low, a known encapsulation method can be applied.

[0010] The reversible thermochromic material of the present invention is used in a more stable and easily handled state by using the above components as they are or by enclosing them in microcapsules. In the present invention, by using the compound represented by the general formula (I) or (II), (1) a very vivid and extremely dark color is developed (2) a change in discoloration (color development-decolorization) (3) Excellent light fastness (4) Efficient microencapsulation, etc. This solves the problems of conventional reversible thermochromic materials.

The component (a) of the present invention, that is, the coloring agent includes triphenylmethane compounds, fluoran compounds, phenothiazine compounds, indolylphthalide compounds, luuco auramine compounds, spiropyran compounds, rhodamine lactams. Compounds, azaphthalide compounds,
And benzoxazine compounds. For example, crystal violet lactone [hereinafter referred to as CVL], 3-
(4-diethylamino-2-ethoxyphenyl) -3-
(1-ethyl-2-methylindol-3-yl) -4
-Azaphthalide, 3- (p-dimethylaminophenyl)
3- (1,2-dimethylindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2
-Methylindol-3-yl) phthalide 3- (p-dimethylaminophenyl) -3- (1,2-dimethylindol-3-yl) phthalide, 3,3-bis (1,2-
Dimethylindol-3-yl) -5-dimethylaminophthalide, 3,3-bis (1,2-dimethylindol-3-yl) -6-dimethylaminophthalide, 3,3-
Bis (9-ethylcarbazol-3-yl) -6-dimethylaminophthalide, 3,3-bis (2-phenylindol-3-yl) -6-dimethylaminophthalide,
-(4-diethylamino-2-ethoxyphenyl) -3
-(1-ethyl-2-methylindol-3-yl)-
4-azaphthalide, 3- (4-diethylamino-2-
Ethoxyphenyl) -3- (1-octyl-2-methylindol-3-yl) -4-azaphthalide;

Benzoylleucomethylene blue, 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-
Dinaphthopyran, 3-phenyl-spiro-dinaphthopyran, 3-benzyl-spiro-dinaphthopyran, 3-methyl-naphtho (6'-methoxybenzo) spiropyran, rhodamine-B-anilinolactam, 3-diethylamino-6methyl-7-chloro Fluoran, 3-diethylamino-5,7-dimethylfluoran, 3-diethylamino-7-chlorofluoran, 3-diethylamino-7,8
-Benzfluoran, 3- (cyclohexylamino)-
7-methylfluorane, 3-diethylamino-6-chloro-7-anilinofluoran, 3-diethylamino-7
-Anilinofluoran, 3-diethylamino-7-dibenylaminofluoran, 3-diethylamino-7-o
-Chloroanilinofluoran, 3-dibutylamino-7
-O-chloroanilinofluoran, 3- (N-ethyl-
Np-Toluidino) -6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3-dibutylamino-6-methyl-7-
Anilinofluoran, 3- (N-methyl-N-cyclohexylamino) -6-methyl-7-anilinofluoran, 3-piperidino-6-methyl-7-anilinofluoran, 3-pyrrolidino-6 Methyl-7-anilinofluoran, 3-diethylamino-7- (m-trifluoromethylanilino) fluoran, 3- (N-ethyl-N-isoamylamino) -6-methyl-7-anilinofluoran and the like No.

The compound of the component (b) of the present invention is a compound represented by the general formula (I) or (II), and can be easily synthesized by the following synthesis method. That is, bis (substituted phenol) sulfides can be obtained by treating a substituted phenol with sulfur dichloride (SCl ₂ ) in the presence of a catalyst. Also, bis (substituted phenol)
Sulfoxides can be obtained by oxidation of bis (substituted phenol) sulfides with hydrogen peroxide, but also by reaction of substituted phenols with thionyl chloride (SOCl ₂ ). Bis (substituted phenol) sulfones can also be obtained by oxidation of bis (substituted phenol) sulfides or bis (substituted phenol) sulfoxides with hydrogen peroxide, but by the reaction of substituted phenols with sulfuryl chloride (SO ₂ Cl ₂ ). Is also obtained.

Specifically, bis- (4-hydroxy-3
-Methylphenyl) sulfide, bis- (4-hydroxy-3-ethylphenyl) sulfide, bis- (4-hydroxy-3-n-propylphenyl) sulfide, bis- (4-hydroxy-3-isopropylphenyl) sulfide, Bis- (3,4-dihydroxyphenyl) sulfide, bis- (4-hydroxy-3-cyclohexylphenyl) sulfide, bis- (3-phenyl-4-
(Hydroxyphenyl) sulfide, bis- (4-hydroxy-3-trifluoromethylphenyl) sulfide, bis- (4-hydroxy-3-trichloromethylphenyl) sulfide, bis- (4-hydroxy-3,5-dimethylphenyl) Sulfide, bis- (4-hydroxy-2-ethylphenyl) sulfide, bis- (4-hydroxy-3-ethyl-5-methylphenyl) sulfide, bis- (4-hydroxy-2-methylphenyl) sulfide, bis- (4-hydroxy-2,6-dimethylphenyl) sulfide, bis- (4-hydroxy-2-
Isopropylphenyl) sulfide, bis- (4-hydroxy-2-tert-butylphenyl) sulfide, bis- (4-hydroxy-2-cyclohexylphenyl) sulfide, bis- (2-phenyl-4-hydroxyphenyl) sulfide, bis -(2,4-dihydroxyphenyl) sulfide,

Bis- (2,4,6-trihydroxyphenyl) sulfide, bis- (4-hydroxy-2-trichloromethylphenyl) sulfide, bis- (2,4-
Dihydroxyphenyl) sulfide, bis- (4-hydroxy-2,5-dimethylphenyl) sulfide, bis- (4-hydroxy-2-methyl-5-ethylphenyl) sulfide, bis- (4-hydroxy-2-methyl-) 5-isopropylphenyl) sulfide, bis- (4
-Hydroxy-2,3-dimethylphenyl) sulfide, bis- (4-hydroxy-2,5 diethylphenyl) sulfide, bis- (4-hydroxy-2,5-diisopropylcyphenyl) sulfide, bis- (4-hydroxy -2,3,6-trimethylphenyl) sulfide, bis- (2,4,5-trihydroxyphenyl) sulfide, bis- (4-hydroxy-2-cyclohexyl-5-methylphenyl) sulfide, bis- (4- Hydroxy-2,5-ditrifluoromethylphenyl) sulfide, bis- (2,3,4-trihydroxyphenyl) sulfide, bis- (2-butyl-4,5-dihydroxyphenyl) sulfide, bis- (4-hydroxy -2,5-diphenylphenyl) sulfide, bis-
(4-hydroxy-octyl-5-methylphenyl) sulfide,

Bis- (4-hydroxy-3-methylphenyl) sulfoxide, bis- (4-hydroxy-3-n
-Propylphenyl) sulfoxide, bis- (4-hydroxy-3,4-dihydroxyphenyl) sulfoxide, bis- (4-hydroxy-3-cyclohexylphenyl) sulfoxide, bis- (3-phenyl-4-hydroxyphenyl) sulfoxide, Bis- (4-hydroxy-3,5-dimethylphenyl) sulfoxide, bis-
(4-hydroxy-2-methylphenyl) sulfoxide, bis- (4-hydroxy-2,6-dimethylphenyl) sulfoxide, bis- (4-hydroxy-2-te)
rt-butylphenyl) sulfoxide, bis- (4-hydroxy-3-ethylphenyl) sulfoxide, bis-
(4-hydroxy-3-isopropylphenyl) sulfoxide, bis- (4-hydroxy-3,4-dihydroxyphenyl) sulfoxide, bis- (4-hydroxy-
3-trichloromethylphenyl) sulfoxide,

Bis- (4-hydroxy-3-methylphenyl) sulfone, bis- (4-hydroxy-3-n-propylphenyl) sulfone, bis- (4-hydroxy-
3,4-dihydroxyphenyl) sulfone, bis- (4
-Hydroxy-3-cyclohexylphenyl) sulfone, bis- (3-phenyl-4-hydroxyphenyl)
Sulfone, bis- (4-hydroxy-3,5-diethylphenyl) sulfone, bis- (4-hydroxy-2-methylphenyl) sulfone, bis- (4-hydroxy-
2,6-dimethylphenyl) sulfone, bis- (4-hydroxy-2-isopropylphenyl) sulfone, bis- (4-hydroxy-3-methylphenyl) sulfone,
Bis- (4-hydroxy-3-isopropylphenyl)
Sulfone, bis- (3,4-dihydroxyphenyl) sulfone, bis- (4-hydroxy-3-trichloromethylphenyl) sulfone,

Bis (2-hydroxy-5-methylphenyl)) sulfide, bis (2-hydroxy-5-te
rt-butylphenyl) sulfide, bis (2-hydroxy-5-tert-amylphenyl) sulfide, bis (2-hydroxy-5-cyclohexylphenyl) sulfide, bis (2-hydroxy-5-cumylphenyl) sulfide, bis (2 -Hydroxy-5-tert
-Octylphenyl) sulfide, bis (2-hydroxy-5-dodecylphenyl) sulfide, bis (2-hydroxy-5-methylphenyl) sulfoxide, bis (2-hydroxy-5-tert-butylphenyl) sulfoxide, bis (2 -Hydroxy-5-tert-amylphenyl) sulfoxide, bis (2-hydroxy-5)
-Cumylphenyl) sulfoxide, bis (5-phenyl-2-hydroxyphenyl) sulfoxide, bis (2-
Hydroxy-5-tert-octylphenyl) sulfoxide, bis (2-hydroxy-5-dodecylphenyl) sulfoxide, bis (2-hydroxy-5-methylphenyl) sulfone, bis (2-hydroxy-5-isopropylphenyl) sulfone, Bis (2-hydroxy-5-tert-butylphenyl) sulfone, bis (2-hydroxy-5-tert-amylphenyl) sulfone, bis (2-hydroxy-5-cyclohexylphenyl) sulfone, bis (2-hydroxy-5) -Cumylphenyl) sulfone, bis (2-hydroxy-5-phenylphenyl) sulfone, bis (2-hydroxy-5-
tert-octylphenyl) sulfone, bis (2-hydroxy-5-dodecylphenyl) sulfone, and the like, but are not limited thereto.

In the compound represented by the general formula (I),
The substituent at the ortho-position of the phenolic hydroxyl group may affect the color density and the stability of the color image due to steric hindrance. In the general formula (I), R _{1 to} R ₄ are
A hydrogen atom, an alkyl group having 1 to 3 carbon atoms, a cyclohexyl group or a phenyl group is preferred, and a hydrogen atom and an alkyl group having 1 to 3 carbon atoms are particularly preferred. The general formula (II)
In the formula, R ₅ is preferably an alkyl group having 1 to 12 carbon atoms, a cyclohexyl group or a phenylalkyl group which may have a substituent having 7 to 10 carbon atoms, particularly an alkyl group having 1 to 12 carbon atoms, a cyclohexyl group. , A benzyl group or a phenethyl group are preferred. In addition, the compound represented by the general formula (I) or (II) can be used in combination with a known compound in accordance with diversification of performance. Known compounds include, for example, compounds having a phenolic hydroxyl group and salts thereof, aromatic carboxylic acid compounds and salts thereof, phosphate esters and salts thereof, disclosed in JP-A-60-173028. , 3-triazole and derivatives thereof.

Examples of the compound of the component (c) of the present invention include alcohols, esters, ethers, ketones, carboxylic acids and acid amides, and examples thereof include the following. Alcohols: There are polyhydric alcohols and derivatives thereof from monohydric alcohols. Specifically, n-octyl alcohol, n-nonyl alcohol, n-decyl alcohol, n-octyl alcohol
-Lauryl alcohol, n-myristyl alcohol, n
-Cetyl alcohol, n-stearyl alcohol, n-
Aikosyl alcohol, n-docosyl alcohol, n-
Melisyl alcohol, isocetyl alcohol, isostearyl alcohol, isodocosyl alcohol, oleyl alcohol, cyclohexanol, cyclopentanol, benzyl alcohol, cinnamyl alcohol, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol , Propylene glycol, butylene glycol, hexylene glycol,
Cyclohexane-1,4-diol, trimethylolpropane, 1,2,6-hexanetriol, pentaerythritol and the like.

Esters: Amyl acetate, octyl acetate, butyl propionate, octyl propionate, phenyl propionate, ethyl caproate, amyl caproate, ethyl caprylate, amyl caprylate, ethyl caprate, caprin Amyl acid, octyl caprate, methyl laurate, ethyl laurate, butyl laurate, hexyl laurate, octyl laurate, dodecyl 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, pal Hexyl formate, octyl palmitate, lauryl palmitate, myristyl palmitate, cetyl palmitate, stearyl palmitate, methyl stearate, ethyl stearate, butyl stearate, hexyl stearate, octyl stearate, lauryl stearate, stearic acid Myristil,
Cetyl stearate, stearyl stearate, methyl behenate, ethyl behenate, propyl behenate,
Butyl behenate, ethyl benzoate, butyl benzoate,
Amyl benzoate, phenyl benzoate, ethyl acetoacetate, methyl oleate, butyl oleate, butyl acrylate, diethyl oxalate, dibutyl oxalate, dimethyl malonate, diethyl malonate, dibutyl malonate, dibutyl tartrate, dimethyl sebacate , Dibutyl sebacate, dimel phthalate, dible phthalate, dioctyl phthalate, dibutyl fumarate, diethyl maleate, triethyl citrate, triglyceride 12-hydroxystearate, castor oil, methyl 12-hydroxystearate, dioxystearin Acid methyl ester and the like.

Ethers: Specifically, diethylene glycol dimethyl ether, diphenyl ether, distearyl ether, butyl ether, hexyl ether,
Diisopropyl benzyl ether, ethylene glycol dibutyl ether, diethylene glycol dibutyl ether, ethylene glycol diethyl ether, ethylene glycol diphenyl ether, ethylene glycol monophenyl ether, and the like. Ketones: specifically, diphenyl ketone, distyryl ketone, diethyl ketone, ethyl butyl ketone, methylhexyl ketone, mesityl oxide, cyclohexanone, propiophenone, benzophenone, 2,4-pentanedione, acetonylacetone, diacetone Acetone alcohol, ketone wax and the like.

Carboxylic acids: specifically, caproic acid,
Caprylic acid, capric acid, lauric acid, myristic acid,
Palmitic acid, stearic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, palmitoleic acid,
Oleic acid, ricinoleic acid, linoleic acid, linolenic acid,
Eleostearic acid, erucic acid and the like. Acid amides: specifically, caprylic amide, capric amide, lauric amide, myristic amide, palmitic amide, stearic amide, behenic amide, oleic amide, benzamide and the like. The above compounds may be used alone or in combination of two or more in order to obtain an arbitrary melting point.

The ratio of each component used in the reversible thermochromic material of the present invention is as follows: (a) :( b) :( c) =
1: 0.1 to 100: 10 to 1000, more preferably (a) :( b) :( c) = 1: 0.1 to 50: 1
It is 0-100. The reversible thermochromic material of the present invention, in addition to the above components, as long as the performance of the color change is not impaired, a dye having no color change, a pigment, an antioxidant, an antioxidant, an ultraviolet absorber, etc. They can be used in combination depending on the situation.

The reversible thermochromic material of the present invention comprises (a) a color former, (b) a compound represented by the general formula (I) or (II), and (c) a compound as main components. It is prepared by mixing, heating and dissolving. However, the reversible thermochromic material composed of the above components is susceptible to the influence of the external environment on the color development and decolorization temperature chemically. Therefore, in order to protect the original functions and to enhance the utilization corresponding to various uses, the present invention is intended to enable the use of several types having different hues and discoloration temperatures under the same conditions. A method of enclosing the reversible thermochromic material in the microcapsule wall film is also adopted. The microcapsule containing the reversible thermochromic material used in the present invention is manufactured by a known method. For example, a microcapsule solution is produced by a coacervation method using gelatin, an interfacial polymerization method, an In-Situ polymerization method, a submerged curing method, or the like.

The microcapsules containing the reversible thermochromic material may be used as they are as an aqueous ink or an aqueous paint, or they may be used as a solid by filtration, centrifugation, drying, or the like. The solidified microcapsules are melted in resin and processed into films, pellets, filaments, etc., attached to fibers, and oil-based inks such as silk screen, gravure, offset, flexo, etc. It can be used for printing on ceramics, glass, fibers and the like, and as a paint for temperature detection and display devices in the industrial field.

[0027]

EXAMPLES The method of the present invention will be described in detail with reference to examples, but the present invention is not limited thereto. Example 1 The following three components (a), (b) and (c) were mixed and dissolved by heating to prepare an internal phase. Component (a): 2.0 g of CVL Component (b): 2.0 g of bis- (4-hydroxy-3-methylphenyl) sulfide Component (c): 46.0 g of atearyl alcohol Microcapsules were produced by the method (A). To 50 g of the microcapsule solution, 10% by weight polyvinyl alcohol (Kuraray "117") was added, and the mixture was stirred.
Coating so that the dry coating amount is 8 g / m ^{2 on high} quality paper.
After drying, a reversible thermochromic material sheet was obtained. The reversible thermochromic material sheet was heated or cooled to measure the color change temperature (the temperature at which color changes from colorless to colorless) and the hue. The results are shown in Table 1 (Table 1, Table 2, Table 3, Table 4, Table 5, Table 6).

Examples 2 to 77 In the same manner as in Example 1 except that the components (a), (b) and (c) shown in Table 1 were used instead of the combination of the three components of Example 1, To prepare the internal phase. With respect to the obtained internal phase, microcapsules were produced by any of the following microencapsulation methods. A reversible thermochromic material sheet was obtained in the same manner as in Example 1 using the obtained microcapsule liquid. The reversible thermochromic material sheet was heated or cooled to measure the color change temperature (the temperature at which color changes from colorless to colorless) and the hue. The results are shown in Table 1. Further, with respect to a part of the reversible thermochromic material sheet, the color density was measured by changing the filter of the Macbeth densitometer. Therefore, although the attained density differs depending on the hue, the higher the number, the higher the density. Further, the reversible thermochromic material sheet was exposed to a carbon arc fedometer (Suga tester) for 1 hour, and the density after the test was measured using a Macbeth densitometer. %). The larger the value, the less fading due to light. The results are shown in Table 2 (Tables 7 and 8).

Microencapsulation method (A) Ethylene maleic anhydride polymer (Monsanto "EMA
-31 "), 25 g of a 10% by weight aqueous solution of water and 60 g of water were mixed, and the pH was adjusted to 4.0 with 10% by weight of NaOH.
After the temperature was maintained at 50 ° C. and 50 g of the above internal phase was emulsified with a homomixer, a methylated methylolmelamine aqueous solution having a solid content of 80% by weight (Mitsui Toatsu Chemical “Euramine T-33”) 15
g was added and kept at 70 ° C. for 2 hours with stirring to obtain a microcapsule liquid having an average particle diameter of 10 μm.

Microencapsulation method (B) 50 g of internal phase, 9 g of acrylonitrile, acrylamide
1 g, 0.1 g of methylenebisacrylamide and 0.2 g of azobisisobutyronitrile were uniformly dissolved.
This was placed in 100 g of 5% by weight polyvinyl alcohol kept at 60 ° C., emulsified using a homomixer, and then kept at 70 ° C. for 3 hours to obtain a microcapsule solution having an average particle diameter of 10 μm.

Microencapsulation method (C) 50 g of the internal phase and 5 g of terephthalic acid dichloride were uniformly dissolved. This was put into 100 g of 5% by weight polyvinyl alcohol (Kuraray “117”) kept at 60 ° C.
After emulsification using a homomixer, 5 g of 1,6-hexamethylenediamine was added, and the mixture was kept at 70 ° C. for 3 hours to obtain a microcapsule liquid having an average particle diameter of 10 μm.

Microencapsulation method (D) 50 g of an internal phase and 5 g of a trimer of hexamethylene diisocyanate having an isocyanurate ring (Coronate EH, manufactured by Nippon Polyurethane Industry) were uniformly dissolved. This is 6
100 g of 5% by weight polyvinyl alcohol (Kuraray “117”) kept at 0 ° C., emulsified using a homomixer, and then 1 g of diethylenetriamine was added.
For 3 hours to obtain a microcapsule liquid having an average particle diameter of 10 μm.

Comparative Examples 1 to 5 In place of bis- (4-hydroxy-3-methylphenyl) sulfide, components (b) and (c) shown in Comparative Examples 1 to 5 in Table 1 were used. As in Example 1,
A reversible thermochromic material sheet was prepared and tested. The results are shown in Tables 1 and 2.

Comparative Examples 6 to 9 Bis- (4-hydroxy-3-methylphenyl) sulfide was used as bisphenol A, and CVL was used as Red-3.
(Comparative Example 6), PSD-V (Comparative Example 7), GreenD
A reversible thermochromic material sheet was prepared and tested in the same manner as in Example 1 except that CF (Comparative Example 8) and PSD-150 (Comparative Example 9) were used. Crystals were partially precipitated in the microcapsule liquid. This may be due to the lack of solubility of bisphenol A in cetyl alcohol. The results are shown in Tables 1 and 2.

(A) a color forming agent of the present invention, (b) a compound represented by the general formula (I) or (II), (c) an alcohol, ester, ether, ketone, carboxylic acid or acid amide. As shown in Table 1, a thermoreversible discoloring material obtained by microencapsulating a compound selected from the group as a component can use various microcapsule methods such as an in-situ method and an interfacial polymerization method. The discolored material sheet provides a wide temperature range and various color hues.

[0036]

[Table 1]

[0037]

[Table 2]

[0038]

[Table 3]

[0039]

[Table 4]

[0040]

[Table 5]

[0041]

[Table 6]

[0042]

[Table 7]

[0043]

[Table 8]

As shown in the comparative example of Table 2, bis- (4
-Hydroxyphenyl) sulfide (Comparative Example 1), bis- (4-hydroxyphenyl) sulfone (Comparative Example 3),
Compounds having no substituent, such as bis- (2-hydroxyphenyl) sulfide (Comparative Example 4), have a high solubility in water, resulting in an insufficient microencapsulation rate. Color density and light resistance were lower than those of Nos. 1 to 29. Bis- (4-hydroxy-tert-butyl-6-methylphenyl) sulfide (Comparative Example 2) is inferior in color density and light resistance, possibly due to steric hindrance of the tert-butyl group at the ortho position of the phenolic hydroxyl group. Met. Comparison between bisphenol A and the compound of the present invention shows that there is a clear difference in light resistance when combined with a color former having low light resistance such as CVL [Comparison between Examples 1 to 29 and Comparative Example 5] . As shown in Comparative Examples 6 to 9, color formers having poor solubility in component (c) (Red-3, PSD-V, GreenDC)
F, PSD-150), when combined with bisphenol A, partially precipitated crystals during microencapsulation and were not completely microencapsulated. Therefore, when a discoloration sheet is produced, the color density becomes low,
The light resistance was also poor [Example 39-Comparative Example 6, Example 48-Comparative Example 7, Example 57-Comparative Example 8, Example 6]
3-Comparison of Comparative Example 9].

[0045]

According to the present invention, (a) an electron-donating color former,
(B) a compound represented by the general formula (I) or (II),
(C) The reversible thermochromic material containing as an ingredient a compound selected from alcohols, esters, ethers, ketones, carboxylic acids or acid amides, develops a very vivid and extremely dark color. Therefore, a change in hue (color development-discoloration) occurs in a narrow temperature range, and stable thermal discoloration can be obtained even in repeated use over a long period of time.
As a result, in addition to the use of the conventional reversible thermochromic material, the invention can be applied to a new use by utilizing the characteristics of the present invention.

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Akihiro Yamaguchi 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Prefecture Examiner, Mitsui Toatsu Chemicals Co., Ltd. Yoko Watanabe (56) JP-A-63-145388 (JP, A) JP-A-4-249194 (JP, A) JP-A-63-59586 (JP, A) JP-A-62-299382 (JP, A) JP-A-63-94878 (JP, A) JP-A-62-273885 (JP, A) JP-A-2-239977 (JP, A) JP-A 2-143898 (JP, A) JP-A-2-219682 (JP, A) ( 58) Field surveyed (Int.Cl. ⁷ , DB name) C09K 9/02 G01K 11/12 CA (STN) REGISTRY (STN)

Claims (2)

(57) [Claims] (A) an electron-donating color former; and (b) a general formula (I). (Wherein, R _1, R ₂ represents a hydrogen atom, C ₁ -C ₃ alkyl group, a halogenated alkyl group of C ₁ -C _3, a hydroxyl group, a cyclohexyl group or a phenyl group, R _1,
When any one of R ₂ is a cyclohexyl group or a phenyl group, the other is a hydrogen atom, and R ₃ and R ₄ are a hydrogen atom,
_A C ₁ -C ₁₅ alkyl group, a C ₁ -C ₁₅ halogenated alkyl group, a hydroxyl group, a cyclohexyl group or a phenyl group, wherein two R ₁ -R ₄ are the same or different, R _{1 to} R ₄ are not simultaneously a hydrogen atom, and n is an integer of 0, 1 or 2) or at least one compound represented by the general formula (II) (Formula 2). , Embedded image (Wherein R ₅ represents a C ₁ -C ₁₂ alkyl group, a C ₃ -C ₁₀ cycloalkyl group, a C ₇ -C ₁₀ aralkyl group or a phenyl group, and two R _{5 s} are the same as each other. And n is an integer of 0, 1 or 2) (c) at least one compound selected from alcohols, esters, ethers, ketones, carboxylic acids and acid amides as a component A reversible thermochromic material characterized by containing. 2. The reversible thermochromic material according to claim 1, wherein the components (a), (b) and (c) are included in a microcapsule wall film.