JPH0319072B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to thermochromic compositions.

Thermochromic colorants containing electron-donating color-forming organic compounds (hereinafter referred to as color formers), color developers, and desensitizers are:
It is publicly known. Such coloring agents are useful as temperature indicators because they produce a so-called thermochromic phenomenon in which the composition changes color or discolors in response to temperature changes. However, since known thermochromic colorant compositions mainly use phenolic compounds as color developers, their uses may be limited in terms of toxicity. Furthermore, since the phenolic compound is not resistant to air oxidation or exposure to sunlight, it also has problems such as unstable thermochromic properties.

The present inventor has conducted various studies in view of the above-mentioned disadvantages of known thermochromic coloring compositions, and has found that when thiourea or its derivatives are used as a color developer, the above-mentioned disadvantages are substantially eliminated. I found that it can be resolved. That is, the present invention provides () at least one electron-donating color-forming organic compound; () thiourea;
Allylthiourea, N-acetylthiourea and
At least one type selected from the color developer consisting of Sym-diphenylthiourea and () at least one type selected from the desensitizers shown below; Alcohols...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, oleyl alcohol, cyclohexanol, benzyl alcohol, ethylene glycol, polyethylene glycol, trimethylolpropane, penta Erythritol, esters...lauryl caproate, octyl caprate, butyl laurate, dodecyl laurate, hexyl myristate, myristyl myristate, octyl palmitate, stearyl palmitate, butyl stearate, cetyl stearate, methyl stearate, behenin lauryl acid,
Cetyl oleate, butyl benzoate, phenyl benzoate, benzyl benzoate, dimethyl sebacate, dibutyl sebacate, Ketones...diethyl ketone, cyclohexanone, acetophenone, benzophenone, dimyristyl ketone, Ethers...dilauryl ether, dicetyl ether , diphenyl ether, ethylene glycol monostearyl ether, ethylene glycol dibutyl ether, diisopropyl benzyl ether, fatty acids...caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid,
Stearic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, partoleic acid, oleic acid, ricinoleic acid, linolenic acid, linoleic acid, sebacic acid, eleostearic acid, erucic acid, acid amides...carboxylic 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.

(hereinafter referred to as the first invention of the present application).

Furthermore, according to the research of the present inventor, the above () ~
It has been found that when a thermosetting or photocurable resin is used in combination with the composition consisting of (), the coloring reaction can be carried out stably and repeatedly. That is,
The present invention further provides () at least one electron-donating color-forming organic compound, () thiourea, allylthiourea, N-acetylthiourea, and Sym-
At least one type selected from color developers consisting of diphenylthiourea, () At least one type selected from the following desensitizers; Alcohols...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, oleyl alcohol, cyclohexanol, benzyl alcohol, ethylene glycol, polyethylene glycol, trimethylolpropane, penta Erythritol, esters...lauryl caproate, octyl caprate, butyl laurate, dodecyl laurate, hexyl myristate, myristyl myristate, octyl palmitate, stearyl palmitate, butyl stearate, cetyl stearate, methyl stearate, behenin lauryl acid,
Cetyl oleate, butyl benzoate, phenyl benzoate, benzyl benzoate, dimethyl sebacate, dibutyl sebacate, Ketones...diethyl ketone, cyclohexanone, acetophenone, benzophenone, dimyristyl ketone, Ethers...dilauryl ether, dicetyl ether , diphenyl ether, ethylene glycol monostearyl ether, ethylene glycol dibutyl ether, diisopropyl benzyl ether, fatty acids...caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid,
Stearic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, partoleic acid, oleic acid, ricinoleic acid, linolenic acid, linoleic acid, sebacic acid, eleostearic acid, erucic acid, acid amides...carboxylic 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.

and () a thermochromic composition containing a thermosetting or photocurable resin (hereinafter referred to as the second invention of the present application).

The color former used in the present invention is not particularly different from those used in known thermochromic colorant compositions. Among these, more preferable compounds are as follows.

Triphenylmethane phthalides...crystal violet lactone, malachite green lactone, etc.

Fluorans: 3,6-diethoxyfluoran, 3-dimethylamino-6-methyl-7-chlorofluoran, 1,2-benz-6-diethylaminofluoran, 3-diethylamino-7-methoxyfluoran, etc.

Phenothiazines: benzoyl leucomethylene blue, methyl leucomethylene blue, ethyl leucomethylene blue, methoxybenzoyl leucomethylene blue, etc.

Indolylphthalides...2-(phenyliminoethanedylidene)-3,3-dimethylindoline, etc.

Spiropyrans...1,3,3-trimethyl-indolino-7'-chloro-β-naphthospiropyran, di-β-naphthospiropyran, benzo-β-
Naphthoisospiropyran, xantho-β-naphthospiropyran, etc.

Leuco auramines...N-acetyl auramine, N-phenyl auramine, etc.

Rhodamine lactams...Rhodamine B lactam, etc.

As the color developer of the present invention, one type or a combination of two or more of thiourea, allylthiourea, N-acetylthiourea, and Sym-diphenylthiourea can be used.

As the desensitizer used in the present invention, those used in known thermochromic colorant compositions can be used. Among them, more preferable examples are as follows.

Alcohols...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, oleyl alcohol, cyclohexanol, benzyl alcohol, ethylene glycol, polyethylene glycol, trimethylolpropane, penta Erythritol, etc.

Esters...Lauryl caproate, octyl caprate, butyl laurate, dodecyl laurate, hexyl myristate, myristyl myristate, octyl palmitate, stearyl palmitate, butyl stearate, cetyl stearate, lauryl behenate, cetyl oleate , butyl benzoate, phenyl benzoate, benzyl benzoate, methyl stearate, methyl sebacate,
Dibutyl sebacate, etc.

Ketones: cyclohexanone, acetophenone, benzophenone, dimyristyl ketone, diethyl ketone, etc.

Ethers: dilauryl ether, dicetyl ether, diphenyl ether, ethylene glycol monostearyl ether, ethylene glycol dibutyl ether, diisopropylbenzyl ether, etc.

Fatty acids: caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid,
Stearic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, partoleic acid, oleic acid, ricinoleic acid, linoleic acid, linolenic acid, eleostearic acid, erucic acid, sebacic acid, etc.

Acid amides...carboxylic 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, erucic acid amide, etc.

The ratio of color former: color developer: desensitizer in the first invention of the present application is usually 1:1/10 to 100:1 to 100:1 by weight.
The ratio is about 100, more preferably 1:1/2 to 50:
It is about 1 to 50. If the amount of the color developer is too large, the reversible color change property, especially the color erasing property, will deteriorate, whereas if the amount of the color developer is insufficient, the color density will be low. If the amount of the desensitizer is too large, the coloring density will be low, whereas if it is insufficient, the decolorizing property will be reduced.

The thermosetting and photocuring resins used in the second invention of the present application are not particularly limited, but include urea resins,
Examples include melamine resin, polyester resin, polyurethane resin, epoxy resin, and modified epoxy resin. These resins are used in combination with a polyamine-based, organic acid-based, amino resin-based, phenolic resin-based, peroxide-based, or other curing agent, if necessary.

Also in the second invention of the present application, the blending ratio of color former: color developer: desensitizer is the same as in the case of the first invention of the present application. The amount of heat or photocurable resin used is the coloring agent,
Usually 1 part by weight of the color developer and desensitizer
The amount is about 100 parts by weight, preferably about 2 to 50 parts by weight. If the amount of heat or photocurable resin is too large, the color density will be low. On the other hand, if the amount of heat or photocurable resin is too small, the adhesiveness of the coating film formed on the surface of the object will decrease, the mechanical strength will also decrease, and the stability of thermochromic properties will not improve. .

Colored pigments, fillers, ultraviolet absorbers, sensitizers, antioxidants, etc. can be added to the thermochromic composition of the present invention, if necessary.

The composition of the present invention is prepared, for example, as follows. However, the preparation method is completely arbitrary and is not limited to the examples below.

When the composition of the first invention of the present application is used as a liquid colorant for writing instrument ink, etc., it is sufficient to dissolve a specific coloring agent, color developer, and desensitizer in a solvent, and the desensitizer may be dissolved in a solvent. In cases where this may occur, the color former and color developer may be dissolved in the desensitizer. Furthermore, when used as a solid colorant, for example, a color former, a color developer, and a desensitizer are uniformly dispersed in an excipient such as heated and melted microcrystalline wax, and then molded into a predetermined shape. and then cool it down.

In the case of the second invention of the present application, a color forming agent, a color developer, and a desensitizer may be uniformly dispersed in a heat- or photocurable resin, and a curing agent may be further added as necessary. When used, it is applied to the surface of a predetermined object and cured.

According to the present invention, the following effects are achieved.

() Since the color developer is non-toxic or has low toxicity, there are no restrictions on its uses.

() The thermochromic property is stable even after repeated use over a long period of time, and the color changes clearly at a certain temperature.

Example 1 1 part of crystal violet lactone (hereinafter "parts" indicate parts by weight), 50 parts of Sym-diphenylthiourea and 50 parts of cetyl alcohol were mixed with bisphenol A type epoxy resin (manufactured by Ciel Chemical Co., Ltd., trademark ""). After uniformly kneading 80 parts of Epicoat 828''), 20 parts of a polyamine curing agent (manufactured by Ciel Chemical Co., Ltd., trademark "Epicure U") was added and further mixed uniformly.

The resulting colorant composition was applied to a glass plate and heated at 120°C for 30 minutes, resulting in an epoxy resin coating that was blue at room temperature. This coating has the property of decolorizing at temperatures above 45℃.
It had excellent adhesion to glass and good water resistance.

Example 2 Fluoran dye (manufactured by Hodogaya Chemical Co., Ltd., trademark “O”)
-DCF”) and 25 parts of thiourea and 50 parts of stearyl alcohol, and the mixture was thoroughly mixed at 80°C.
The resulting mixture was treated with 100% pisphenol A type epoxy resin (manufactured by Dow Chemical Co., Ltd., trademark "DER337").
1, and then a polyamine curing agent (Example 1).
20 parts (same as above) and 0.1 part of an acrylate ultraviolet absorber (manufactured by Cyclo Kasei Co., Ltd., trademark "Sea Soap 501") were added and mixed.

After applying the obtained colorant composition to the ceramic plate,
When heated at 120°C for 30 minutes, an orange coating film was obtained at room temperature. This coating showed the property of discoloring at temperatures above 62°C, and had excellent adhesion to ceramic plates and water resistance.

Example 3 After uniformly dissolving 1 part of crystal violet lactone, 5 parts of allylthiourea, and 50 parts of myristyl alcohol under heating, a urethane-modified epoxy resin (manufactured by Mitsui Toatsu Chemical Industries, Ltd., trademark "810ST") was prepared.
100 parts and kneaded uniformly.

The resulting composition was applied to a paper surface, heated at 80°C for 10 minutes, and then left at room temperature for 3 days to form a blue epoxy resin coating. This coating film is heated at 38℃
It exhibited a blue color below, and disappeared when the temperature exceeded 38°C.

Example 4 After melting 1 part of rhodamine B lactam and 25 parts of diphenylthiourea-based compound (manufactured by Ouchi Shinko Co., Ltd., trademark "Noxeura-C") in 25 parts of cetyl alcohol, epoxy acrylate-based photocurable resin ( 200 parts of UVX-N12A (manufactured by Three Bond Co., Ltd., trademark: "UVX-N12A") and kneaded uniformly.

The resulting composition was applied to a glass plate and then cured with ultraviolet light, yielding a dark pink coating. This coating had good adhesion to glass and exhibited the property of decolorizing at temperatures above 55°C.

Example 5 1 part of crystal violet lactone, 20 parts of allylthiourea and 40 parts of stearic acid were melted under heating, and then sufficiently mixed with 100 parts of epoxy acrylate resin (manufactured by Showa Kobunshi Co., Ltd., trademark "Lipoxy R840"). Kneaded.

1.5 parts of methyl ethyl ketone peroxide and 0.5 parts of cobalt naphthenate were added to the resulting mixture, applied on a glass plate, and left at room temperature for one week.
A blue-green coating was obtained. When this coating is heated, 75
The color disappeared at °C.

Example 6 1 part of 3,6-diethoxyfluorane, 5 parts of N-acetylthiourea, and 50 parts of oleic acid were thoroughly mixed under heating to obtain a homogeneous solution.

The resulting ink-like composition was colorless at room temperature, but developed a yellow color when applied to a paper surface and cooled to 5° C. or below.

Example 7 After heating and dissolving 1 part of crystal violet lactone, 25 parts of thiourea and 50 parts of cetyl alcohol, 100 parts of microcrystalline wax was added and melted uniformly by heating, poured into a crayon mold, and cooled. and molded it.

The obtained solid marker was pale blue at room temperature, and when applied to the surface of an object and heated, the color disappeared at about 55°C.

Example 8 1 part of Crystal Violet Lactone, Hansa Yellow 10G (manufactured by Hoechst, CIPigment Yellow 3)
After heating and mixing 0.3 parts of Sym-diphenylthiourea, 25 parts of myristic acid, and 50 parts of myristic acid at 135°C, an epoxy-acrylic composite emulsion (Mitsui Toatsu Chemical Co., Ltd.) was prepared.
The mixture was uniformly dispersed in 150 parts of Almatex Z-112 (trademark manufactured by Co., Ltd.). After applying this ink to high-quality paper, it was left at room temperature for one week to fully dry and harden. The resulting coating film is green at room temperature, but at 45
It turned yellow at temperatures above ℃.

Example 9 The same procedure as in Example 1 was performed except that lauryl alcohol was used instead of cetyl alcohol, and the resulting colorant composition was applied to a glass plate to form an epoxy resin coating that was colorless at room temperature. Obtained.

This coating film exhibited a blue color at temperatures below 16°C and disappeared at temperatures above 16°C, and had good adhesion to glass and water resistance.

Example 10 A colorant composition obtained in the same manner as in Example 1 except that octyl alcohol was used instead of cetyl alcohol was applied to a glass plate to obtain an epoxy resin coating that was colorless at room temperature.

This coating exhibits a blue color at temperatures below -50℃;
The above compositions had the property of decoloring, and had good adhesion to glass, water resistance, etc.

Example 11 A colorant composition obtained in the same manner as in Example 5 except that dimethyl sebacate was used instead of stearic acid was applied to a glass plate to obtain a colorless coating film at room temperature.

This coating film exhibits a bluish-green color at temperatures below 5°C;
The above had the property of decoloring.

Example 12 A colorant composition obtained in the same manner as in Example 5 except that methyl stearate was used instead of stearic acid was applied to a glass plate to obtain a blue coating film at room temperature.

This coating film exhibited a blue color at temperatures below 37°C and disappeared at temperatures above 37°C.

Example 13 A colorant composition obtained in the same manner as in Example 5 except that phenyl benzoate was used instead of stearic acid was applied to a glass plate to obtain a coating film that was colorless at room temperature.

This coating exhibits a blue color at temperatures below -24℃;
The above had the property of decoloring.

Example 14 A colorant composition obtained in the same manner as in Example 5 except that benzyl benzoate was used instead of stearic acid was applied to a glass plate to obtain a coating film that was colorless at room temperature.

This coating exhibits a blue color at temperatures below -21℃;
The above had the property of decoloring.

Example 15 A colorant composition obtained in the same manner as in Example 5 except that diethyl ketone was used instead of stearic acid was applied to a glass plate to obtain a coating film that was colorless at room temperature.

This coating exhibits a blue color at temperatures below -76℃;
The above had the property of decoloring.

Example 16 A colorant composition obtained in the same manner as in Example 5 except that cyclohexanone was used instead of stearic acid was applied to a glass plate to obtain a coating film that was colorless at room temperature.

This coating exhibits a blue color at temperatures below -85℃;
The above had the property of decolorizing.

Example 17 A colorant composition obtained in the same manner as in Example 5 except that acetophenone was used instead of stearic acid was applied to a glass plate to obtain a coating film that was colorless at room temperature.

This coating exhibits a blue color at temperatures below -40℃;
The above had the property of decoloring.

Example 18 A colorant composition obtained in the same manner as in Example 5 except that diisopropyl benzyl ether was used instead of stearic acid was applied to a glass plate to obtain a coating film that was colorless at room temperature.

This coating film exhibits a bluish-green color at temperatures below -52°C;
It had the property of decolorizing at temperatures above ℃.

Example 19 A colorant composition obtained in the same manner as in Example 1 except that stearamide was used instead of cetyl alcohol was applied to a glass plate to obtain an epoxy resin coating that was blue at room temperature.

This coating film exhibited a blue color at temperatures below 85°C and disappeared at temperatures above 85°C, and had good adhesion to glass and water resistance.

Example 20 A colorant composition obtained in the same manner as in Example 5 except that erucic acid amide was used instead of stearic acid was applied to a glass plate to obtain a blue coating film at room temperature.

This coating film exhibited a blue color at temperatures below 73°C and disappeared at temperatures above 73°C.

Example 21 A colorant composition that is colorless at room temperature was obtained by the same procedure as in Example 6 except that gapric acid was used instead of oleic acid.

The resulting coating film developed a yellow color when the temperature was lower than -8°C.

Example 22 A colorant composition that is yellow at room temperature was obtained in the same manner as in Example 8 except that decyl alcohol was used instead of myristic acid.

The resulting coating film exhibited a green color when the temperature was below -10°C, and a yellow color when the temperature was above -10°C.

Example 23 A colorant composition that is green at room temperature was obtained by the same procedure as in Example 8 except that erucic acid amide was used instead of myristic acid.

The resulting coating film exhibited a green color when the temperature was below 73°C, and a yellow color when the temperature was above 73°C.

Example 24 A colorant composition that was yellow at room temperature was obtained by the same procedure as in Example 8 except that oleic acid was used instead of myristic acid.

The resulting coating film exhibited a green color when the temperature was below 5°C, and a yellow color when the temperature was above 5°C.

Example 25 A colorant composition obtained in the same manner as in Example 1 except that oleic acid amide was used instead of cetyl alcohol was applied to a glass plate to obtain an epoxy resin coating that was blue at room temperature.

This coating film exhibited a blue color at temperatures below 82°C and disappeared at temperatures above 82°C, and had good adhesion to glass and water resistance.

Example 26 A colorant composition that is green at room temperature was obtained in the same manner as in Example 8 except that lauric acid amide was used instead of myristic acid.

The resulting coating film exhibited a green color when the temperature was below 88°C, and a yellow color when the temperature was above 88°C.

Example 27 35 parts of sebacic acid instead of 25 parts of cetyl alcohol
The same operation as in Example 4 was carried out except that the colorant composition obtained was applied to a glass plate,
A deep pink coating film was obtained at room temperature.

This coating film exhibits a deep pink color at temperatures below 105°C.
It had the property of decolorizing at temperatures above 0.degree. C., and its adhesion to glass was good.

Example 28 The same operation as in Example 5 was carried out except that ethylene glycol dibutyl ether was used instead of stearic acid, and a coating film that was colorless at room temperature was obtained from the resulting colorant composition.

This coating film exhibits a bluish-green color at temperatures below -78°C.
It had the property of decolorizing at temperatures above ℃.

Example 29 The procedure of Example 8 was repeated except that dicetyl ether was used instead of myristic acid, and a green coating film was obtained from the resulting colorant composition at room temperature.

This coating took on a green color at temperatures below 49°C and a yellow color at temperatures above 49°C.

Claims (1)

[Scope of Claims] 1 () At least one electron-donating color-forming organic compound; () At least one color developer selected from thiourea, allylthiourea, N-acetylthiourea, and Sym-diphenylthiourea. species and () at least one selected from the desensitizers shown below; alcohols...n-octyl alcohol, n-octyl alcohol;
-nonyl alcohol, n-decyl alcohol,
n-lauryl alcohol, n-myristyl alcohol, n-cetyl alcohol, n-stearyl alcohol, n-icosyl alcohol, n
-docosyl alcohol, oleyl alcohol,
Cyclohexanol, benzyl alcohol, ethylene glycol, polyethylene glycol,
Trimethylolpropane, pentaerythritol, esters...lauryl caproate, octyl caprate, butyl laurate, dodecyl laurate, hexyl myristate, myristyl myristate, octyl palmitate, stearyl palmitate, butyl stearate, cetyl stearate, Methyl stearate, lauryl behenate, cetyl oleate, butyl benzoate, phenyl benzoate, benzyl benzoate, dimethyl sebacate, dibutyl sebacate, ketones...diethyl ketone, cyclohexanone, acetophenone, benzophenone, dimyristyl ketone, ethers …Dilauryl ether, dicetyl ether, diphenyl ether, ethylene glycol monostearyl ether, ethylene glycol dibutyl ether, diisopropyl benzyl ether, fatty acids…caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearin Acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, partoleic acid, oleic acid, ricinoleic acid, linolenic acid, linoleic acid, sebacic acid, eleostearic acid, erucic acid, acid amides...carboxylic acid amide, caprylic acid 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. A thermochromic composition containing. 2 () At least one type of electron-donating color-forming organic compound, () At least one type of color developer selected from thiourea, allylthiourea, N-acetylthiourea, and Sym-diphenylthiourea, () The following: At least one kind selected from the desensitizers shown; Alcohols...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, oleyl alcohol,
Cyclohexanol, benzyl alcohol, ethylene glycol, polyethylene glycol,
Trimethylolpropane, pentaerythritol, esters...lauryl caproate, octyl caprate, butyl laurate, dodecyl laurate, hexyl myristate, myristyl myristate, octyl palmitate, stearyl palmitate, butyl stearate, cetyl stearate, Methyl stearate, lauryl behenate, cetyl oleate, butyl benzoate, phenyl benzoate, benzyl benzoate, dimethyl sebacate, dibutyl sebacate, ketones...diethyl ketone, cyclohexanone, acetophenone, benzophenone, dimyristyl ketone, ethers …Dilauryl ether, dicetyl ether, diphenyl ether, ethylene glycol monostearyl ether, ethylene glycol dibutyl ether, diisopropyl benzyl ether, fatty acids…caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearin Acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, partoleic acid, oleic acid, ricinoleic acid, linolenic acid, linoleic acid, sebacic acid, eleostearic acid, erucic acid, acid amides...carboxylic acid amide, caprylic acid 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. and () a thermochromic composition containing a thermosetting or photocurable resin.