JPH0376786A - Thermochromic composition - Google Patents

Abstract

PURPOSE:To obtain a thermochromic composition of which the range of hysteresis can be changed freely according to heating temperature by mixing a leuco dye, a color-developing substance that develops the color of the leuco dye and two specific types of solvents. CONSTITUTION:A thermochromic composition is obtained by mixing a colorless or very light-colored leuco dye [e.g. 3,3'-dimethoxyfluoran (yellow) or 3- diethylamino-7-dibenzyl-aminofluoran (dark green)]; a color-developing substance that develops the color of the leuco dye when it is brought into contact with the leuco dye (e.g. phenol or aromatic hydroxycarboxylic acid); an alkyl ester of an aliphatic carboxylic acid that discolors the dye when heated together with the leuco dye and the color developing substance (e.g. octyl caprylate) and an ester containing an aromatic ring (e.g. phenyl acetate). When this composition is exposed to a temperature higher than the complete discoloration temperature (T2) of a color density-temperature curve by t deg.C, its range of hysteresis expands by Ht. That is, the hysteresis range of this composition can be changed freely by changing the temperature of heating.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a thermochromic composition whose hysteresis width can be freely changed depending on the heating temperature.

Conventional techniques and problems Colorless or very light-colored leuco dyes, color-developing substances that develop colors when they come into contact with leuco dyes, and decolorizing dyes when heated in the coexistence of leuco dyes and color-developing substances. Solvent 3
It has been said that a thermochromic composition composed of a mixture of components reversibly changes color from colored to colorless or from colorless to colored at a certain temperature. However, in reality, the decoloring line and the coloring enclosing line in the colored density-temperature four lines of these compositions do not match, and there is a deviation. This deviation width is called the "hysteresis width."

Means for Solving the Problems In order to deeply investigate the properties of the above-mentioned thermochromic compositions, the present inventors have conducted intensive studies on the individual components constituting these compositions. As a result, when a combination of two specific solvents is used together with a leuco dye and an acid developer, the hysteresis width can be freely expanded depending on the heating temperature, creating a completely unprecedented type of thermochromic composition. The present invention was completed based on the discovery that the following can be obtained.

That is, the present invention provides (a) a colorless or very light-colored leuco dye, (b) a color-developing substance that causes the dye to develop color upon contact with the leuco dye, and (c) coexistence of the leuco dye and the color-developing substance. Contains an alkyl ester of aliphatic carboxylic acid and esters having at least one aromatic ring in the molecule, which decolorizes the dye when heated to The present invention relates to a thermochromic composition whose hysteresis width increases by ΔHt when exposed to a temperature 64° C. higher.

According to the research of the present inventor, (a) a colorless or very light-colored leuco dye, (b) a color-developing substance that causes the dye to develop color upon contact with the leuco dye, and (c) a leuco dye and a color-developing substance. A thermochromic composition containing an alkyl ester of aliphatic carboxylic acid and an ester having at least one aromatic ring in the molecule, which decolorizes the dye when heated in the coexistence with Temperature curve complete discoloration temperature (T2
), the hysteresis width becomes ΔH.
It has been found that the composition has the property of expanding t, and therefore, by changing the heating temperature, a plurality of hysteresis widths can be obtained with one composition.

In order to further clarify the characteristics of the composition of the present invention, description will be given with reference to the color density-temperature curve of the composition shown in FIG.

That is, the composition of the present invention is colored in the temperature range up to T1 (color-bleaching starting temperature), begins to fade when heated to T1, and becomes colorless at T2 (complete color-bleaching temperature). When cooled from T2, coloring starts at T3 (coloring start temperature) and complete coloring occurs at TA (complete coloring temperature). In other words, the color fading curve (temperature range where color fades due to heating, Tl-72)
and color development curve (temperature range where color develops by cooling, Ta'-T3
), and this deviation width is the "hysteresis width." Specifically, the "hysteresis width" ΔH is expressed as a value obtained by subtracting the average value of the coloring start temperature and complete coloring temperature from the average value of the coloring start temperature and complete coloring temperature. Therefore, this is the hysteresis width in the above case.

The composition of the present invention is heated at a temperature higher than T2, that is, T
After heating to 2+Δt (in this case as well, the color completely disappears at T2), the color starts to develop at a temperature T3' lower than T3, and completely develops at a temperature T,/ lower than T4.

As a result, the hysteresis width ΔH increases by ΔHt, and Ho+
ΔHt.

It can be seen from the graph shown in FIG. 2 that there is a positive correlation between Δt and ΔHt in the composition of the present invention up to ΔtM. When Δt becomes the temperature ΔtM, ΔHt becomes the maximum hysteresis width HMAx, and even if Δt exceeds ΔtM, the hysteresis width does not increase any further. Normally, ΔHt becomes the maximum hysteresis width HMAx at 5°C and Δt<
(200-72)℃, and Δt is (200-T2
)'c or higher, the hysteresis width remains constant at HMAx. Further, the maximum hysteresis width HMAX is usually in a range of about 5 to 30°C.

Such characteristics of the composition of the present invention are completely unknown in the past, and are first manifested when two specific solvents are used in combination with a leuco dye and an acid developer.

The composition of the present invention can be applied to various uses. For example, after cooling paper, film, etc. to which the composition of the present invention has been applied to develop color on the entire surface, letters, designs, etc. are drawn using multiple thermal pens with different temperatures, and then cooled depending on the importance, frequency of use, etc. By adjusting the temperature, it is possible to arbitrarily erase only a portion of these designs, letters, etc., and it is also possible to erase all of them and draw them over and over again. Utilizing these characteristics, it can be applied to various recording cards, writing cards, blackboards, etc.

Further, the temperature can be determined by measuring the relationship between heating temperature and hysteresis width in advance, heating to an appropriate temperature, and measuring the hysteresis width. After measuring the hysteresis width, by allowing the color to develop completely, it can be used repeatedly to measure temperature. Utilizing this characteristic of storing the history of temperature increases and decreases with a hysteresis width, it can also be applied to storage temperature sensing labels.

In addition, it can be applied as a color effect product to clothing, interior goods, toys, miscellaneous goods, etc.

The colorless or light-colored leuco dye (a) constituting the thermochromic composition of the present invention is not particularly limited, and known ones can be used. As a specific example, for example, 3.3'
-dimethoxyfluoran (yellow), 3,3'-dibutoxyfluoran (yellow), 3-chloro-6-phenylaminofluoran (yellow oak), 3-diethylamino-6-methylchlorofluoran (red-orange), 3-diethyl-7,8-
Benzofluorane (P), 3.3', 3'-tris (P)
-dimethylaminophenyl)phthalide (blue-purple), 3.
3'-bis(P-dimethylaminophenyl)phthalide (
green), 3-diethylamino-7-dibenzylaminofluorane (dark line), 3-diethylamino-6-methyl-7
Examples include substituted phenylmethane and fluoran derivatives such as -phenylaminofluorane (black), various indolylphthalide dyes (blue to green), spiropyrans (yellowish brown to reddish green), and these 1 A species or two or more species can be used.

There are no particular restrictions on the color developing substance that can cause the leuco dye to develop color, and any known color developing substance can be used. Specific examples include phenols, oxyaromatic carboxylic acids, carboxylic acids, azoles and their esters or amides, as well as lithium, sodium, calcium, magnesium, aluminum, zinc, tin, titanium, and nickel. Examples include metal salts such as, and one or more of these can be used.

Specific examples of phenols include phenol,
m-cresol, p-cresol, p-nonylphenol, 0-phenylphenol, p-phenylphenol, bisphenol A1 bisphenol F1 β-naphthol, 1,5-dihydroxynaphthalene, resorcin, catechol, pyrogallol, phenolic resin oligomer
Examples include trimers of p-chlorophenol formaldehyde condensates. Specific examples of oxyaromatic carboxylic acids include salicylic acid, p-oxybenzoic acid, and p-oxybenzoic acid.
Examples include ethyl oxybenzoate, methyl salicylate, resorcinic acid, gallic acid, butyl gallate, β-oxynaphthoic acid, β-oxynaphthoic acid amide, methyl β-oxynaphthoate, and tannic acid. Specific examples of carboxylic acids include phthalic acid, benzoic acid, terephthalic acid, pyromellitic acid, trimellitic acid, toluic acid, l,2-oxystearic acid, oxalic acid, lauric acid, stearic acid, tartaric acid, and citric acid. , anthranilic acid and the like. Specific examples of azoles include, for example, 5
-Chlorbenzotriazole, 5-butylbenzotriazole, bisbencitriazolyl-5-methane, 4-benzotriazolesulfonic acid, benzotriazole-5
-carboxylic acid, 5-oxybenzotriazole, 1-benzyl-5-oxybenzotriazole, triazoledicarboxylic acid, tetrazole, oxybenzimidazole and the like. The color developer can be used alone or in combination of two or more.

In the present invention, two types of solvents are used as the solvent for decolorizing the leuco dye by heating together with the leuco dye (a) and the color developing substance (b), namely, an alkyl ester of an aliphatic carboxylic acid and an aliphatic carboxylic acid alkyl ester and a An ester having at least one aromatic ring is used in combination. When these two types of solvents are used together with (a) and (b), the hysteresis width is expanded for the first time.

The alkyl ester of aliphatic carboxylic acid includes an aliphatic carboxylic acid having about 2 to 26 carbon atoms, preferably about 8 to 22 carbon atoms, and an aliphatic carboxylic acid having about 1 to 22 carbon atoms, preferably 1 to 18 carbon atoms.
Use esters with alkanols of degrees. Examples of the esters include octyl caprylate, decyl caprylate, myristyl caprate, cetyl caprate,
Ethyl laurate, decyl laurate, lauryl laurate, myristyl laurate, cetyl laurate, stearyl laurate, methyl myristate, decyl myristate, lauryl myristate, myristyl myristate, cetyl myristate, methyl palmitate, palmitic acid Decyl, lauryl palmitate, cetyl palmitate, stearyl palmitate, methyl stearate,
Examples include butyl stearate, octyl stearate, stearyl stearate, etc., and these may be used singly or in combination.
Can be used in combination with more than one species.

Examples of esters having at least one aromatic ring in the molecule include esters of aliphatic carboxylic acids having about 2 to 26 carbon atoms and phenol, and esters of aliphatic carboxylic acids having about 2 to 26 carbon atoms and alkanol moieties. Esters of aryl-substituted alkanols having about 1 to 6 carbon atoms, 2 to 6 carbon atoms
Esters of aliphatic unsaturated carboxylic acids of about 26 carbon atoms and phenols, esters of aromatic carboxylic acids and aliphatic alcohols of about 2 to 26 carbon atoms, esters of aromatic carboxylic acids and phenols, and esters of aromatic carboxylic acids and alkanol moieties. Esters of aryl-substituted alkanols with about 1 to 6 carbon atoms, esters of aryl-substituted alkanols with about 1 to 6 carbon atoms in the alkanol part and aliphatic alcohols with about 2 to 26 carbon atoms, aromatic alcohols and esters of aryl-substituted alkanols with about 2 to 26 carbon atoms. 22
Examples include esters with aliphatic carboxylic acids of various degrees. These esters contain an alkyl group having about 1 to 6 carbon atoms, an alkoxy group having about 1 to 6 carbon atoms, a hydroxy group, a halogen atom, etc. as a substituent on at least one aromatic ring in the molecule. You may do so. Specific examples of the esters are listed below.

Examples of esters of aliphatic carboxylic acids and phenols include phenyl acetate, 2,3,4-trimethoxyphenyl acetate, pentachlorophenyl laurate, phenyl stearate, p-methylphenyl stearate, phenyl palmitate, and p-palmitate. -Methylphenyl, p-biphenyl palmitate, acetylgraiacol, and the like. Examples of esters of aliphatic carboxylic acids and aryl-substituted alkanols include benzyl caprate, benzyl laurate, benzyl myristate, and benzyl stearate. Examples of the ester of aliphatic unsaturated carboxylic acid and phenol include 2,4,6-dribromophenyl acrylate and 2,4,6-dribromophenyl methacrylate. Examples of esters of aromatic carboxylic acids and aliphatic alcohols include octyl benzoate, lauryl benzoate, oleyl benzoate, stearyl p-methylbenzoate, cetyl p-methylbenzoate, p-
Myristyl t-butylbenzoate, cecyl p-methoxybenzoate, ethyl p-chlorobenzoate, cecyl p-chlorobenzoate, myristyl p-methylbenzoate, ethyl toluate, methyl p-oxybenzoate, p-stearoxybenzoate Examples include methyl acid, methyl benzoylbenzoate, dimethyl phthalate, dioctyl phthalate, didecyl phthalate, diheptyl isophthalate, nonyl isophthalate, octyl terephthalate, and didecyl terephthalate. Examples of the ester of aromatic carboxylic acid and phenol include phenyl benzoate and diphenyl terephthalate. Examples of the ester of aromatic carboxylic acid and aryl-substituted alkanol include benzyl benzoate and phenylethyl benzoate. Examples of the ester of aryl-substituted alkanol and aliphatic alcohol include lauryl benzylate and myristyl benzylate. As an ester of aromatic alcohol and aliphatic carboxylic acid,
Examples include β-naphthyl palmitate, dihydroxynaphthalene distearate, and the like. These esters can be used alone or in combination of two or more.

The proportion of the alkyl ester of aliphatic carboxylic acid and the ester having at least one aromatic ring in the molecule is not particularly limited and may be selected as appropriate from a wide range. It may be blended in an amount of about 90% by weight, preferably about 30 to 70% by weight.

The composition of the present invention can be produced by mixing the above components. The blending ratio of each of the above components is not particularly limited and can be appropriately selected from a wide range, but the usual weight ratio is 1 part of the color developer material of (B) to 1 part of the coir dye of (A) above. 2-2
It is sufficient to use about 0.5 to 50 of the solvent (c).

The composition of the present invention may optionally contain various agents such as surfactants, drying agents, antifoaming agents, thickeners, viscosity modifiers,
Antisettling agents, crosslinking agents, catalysts, dyes, organic pigments, inorganic pigments, fluorescent pigments, phosphorescent pigments, extender pigments, metal powders, metal soaps, foaming agents, foam capsules, optical brighteners, ultraviolet absorbers,
It may contain ultraviolet stabilizers, antioxidants, antiaging agents, oils and fats, plasticizers, electrolytes, acids, alkalis, rust preventives, antioxidants, reduction inhibitors, and the like.

In the present invention, the composition of the present invention may be granulated.

Due to granulation, even under high heat or high pressure, some or all of the above three components (a) to (c) constituting the composition of the present invention will not be dispersed out of the system, and moreover, Part or all of the three components will not be destroyed by entry of solvents, emulsifiers, etc. from the outside.

First, the composition of the present invention is uniformly mixed with a thermosetting resin and granulated according to a known method such as interfacial polymerization or 1n-site polymerization. For granulation, the mixture may be crushed and classified after hardening. Alternatively, granulation treatment may be performed before curing. For example, granulation is performed by stirring and emulsifying the above mixture in hot water containing an emulsifier, adding a catalyst if necessary, and continuing heating. As the emulsifier, any known emulsifier used in this field can be used, such as anionic interfaces such as alkyl sulfonates, alkylnaphthalene sulfonates, alkyl sulfates, alkyl ether sulfates, and alkyl ether phosphates. Examples include activators, ionic surfactants such as aliphatic quaternary ammonium salts, and nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene polyoxypropylene block polymers, and polyoxyethylene sorbitan fatty acid esters. .

Also, known catalysts can be used, such as peroxides, organic amines or salts thereof, organic acids or metal salts thereof, inorganic acids or metal salts thereof, isocyanates, and ethyleneimines. Any known thermosetting resin can be used, and examples include common thermosetting resins such as polyester resin, polyurethane resin, epoxy resin, urea resin, benzoguanamine resin, melamine resin, and epoxy phthalate resin. .

By adding the granules obtained above to an aqueous solution of a hydrophilic polymer compound and adding a gelling agent thereto while stirring, a coagulated film of the hydrophilic polymer compound is formed on the surface of the granules,
Thermoreversible color-changing granules incorporating the composition of the invention can be obtained. The hydrophilic polymer compound may be one that coagulates with acids, alkaline electrolytes, heavy metals, aldehydes, and relatively ionic substances. As a specific example,
For example, natural polymer compounds such as alginate, carrageenan, bebutin, semi-synthetic polymers such as cationized starch, carboxymethyl cellulose, carboxymethylated starch, carboxymethylated guar gum, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid amide. , polymaleic acid copolymer, etc.
A species or two or more species can be used. In addition, as a gelling agent,
Acids, alkaline electrolytes, heavy metals, aldehydes and relatively ionic substances can be used.

The blending ratio of each component compound during granulation is not particularly limited and can be appropriately selected from a wide range. Further, the particle size of the granules is not particularly limited, but may be generally about 1 to 50 μm, preferably about 3 to 15 μm.

The composition of the present invention and the thermochromic granules containing the same can be applied to various articles in exactly the same manner as conventional thermochromic compositions. For example, it can be blended with synthetic resins, waxes, low-molecular monomers, etc. to make molded products, sheets, films, filaments, etc., or it can be blended with printing inks and paints to produce paper, synthetic resin molded products, synthetic resin films, fiber fabrics, etc. It may be printed or painted on the surface of knitted fabric, mono or multifilament, glass, ceramics, leather, metal, wood, etc.

Effects of the Invention The composition of the present invention has the characteristic that its hysteresis width can be changed to a white center depending on the heating temperature.

Therefore, one composition can have multiple hysteresis widths.

Moreover, a more advanced color change effect can be obtained by using two or more types of the composition of the present invention or its granules, or a conventional thermochromic substance.

EXAMPLES Reference examples, working examples, and comparative examples are given below to make the present invention even clearer. In the examples, "part" and "%"
” indicates “parts by weight” and “% by weight”, respectively, unless otherwise specified.

Example I NCR [leuco dye, Hodogaya Chemical Industry ■] 3 parts, 5-chlorobenzotriazole 6 parts, octyl terephthalate 3
0 parts and 20 parts of lauryl laurate were melted while uniformly mixed, and the mixture was poured into 200 g of water containing 2 parts of Demol N [surfactant manufactured by Kao ■] heated to 90°C, and the precipitated emulsion was dissolved. The stirring speed was adjusted so that the average particle size was about 3 μm. 50% under stirring when the emulsification state stabilizes.
Add 30 parts of methylolmelamine aqueous solution (thermosetting resin), then 2 parts of acid catalyst (10% ammonium chloride aqueous solution),
Stirring was continued at 90° C. for 1 hour to obtain a solidified product in the form of oil droplets. This was taken out and heat treated at 120° C. for 3 hours in a hot air dryer to completely solidify it.

The obtained granules were dissolved in a 3% polyvinyl alcohol aqueous solution.
120 parts of a 10% aqueous carboxymethylcellulose solution (hydrophilic polymer compound) was added thereto, and 13 parts of a 10% aqueous calcium chloride solution was gradually added thereto under strong stirring. After stirring for 30 minutes, the granules were removed, dried and the outer layer was coated with carboxymethyl cellulose. Thermochromic granules with an average particle size of 5 μm were obtained.

This thermochromic granular material exhibited a red color at temperatures below 26°C, but began to fade at 26°C and became colorless at 30°C.

Upon subsequent cooling, color development started at 22°C and turned red again at 18°C. That is, the normal hysteresis width (Ho) of this particulate material was 8°C.

Next, when the temperature (T) was raised to 40 to 140°C and then cooled, the hysteresis width (ΔH) increased as the heating temperature range (Δt=T−30) increased, and remained constant above 120°C. The relationship between heating temperature and hysteresis width is shown in Table 1 below.

Table 1 Reference Example 1 Parchment paper with silicone treatment on one side (98g
/ rrr ) was coated with an adhesive [trade name: SK Dyne 101, manufactured by Block Chemical Industry ■] to a thickness of 40 μm using a roll coater, and after air-drying, a polyester film (thickness 25 μm) was applied on top of it. ) to create a base sheet for tack seals.

On the polyester film of the base sheet, 10 parts of the thermochromic granular material obtained in Example 1 and a fluorescent pigment [trade name Niger Yellow M'F2G5 manufactured by Matsui Shiki Kagaku Kogyo Co., Ltd.]
1 part, ethylene vinyl acetate copolymer resin [Product name: EV-
40, 25% xylene solution 9 manufactured by Mitsui Toatsu Chemical Industry Co., Ltd.
The printing ink consisting of 0 copies was printed on the entire surface using a screen plate and thoroughly dried. A transparent polypropylene film (thickness 5.5
A 0 μm) adhesive-coated surface was attached, laminated under heat, and cut with a slitter to obtain two 2 cm thermosensitive color-changing tack stickers.

The tack seal was reddish-orange at temperatures below 26°C, but turned yellow at 30°C. Upon subsequent cooling, a red color began to develop at 22°C and returned to its original red-orange color at 18°C.

This tack seal was passed through a drying oven and then cooled, and the hysteresis width ΔH was measured and found to be approximately 31°C. From Table 1, since ΔH at 80°C is 30°C and ΔH at 90°C is 32°C, it can be seen that the maximum temperature in the drying oven was 85°C. Moreover, it can be used repeatedly to measure the maximum temperature after it is completely colored, and there is no need to observe it between measurements.

Example 2 0ico dye [Product name: B-63, ■ Manufactured by Hodogaya Chemical Industry]
Using 3 parts, 6 parts of bisphenol A, 30 parts of myristyl p-chlorobenzoate and 20 parts of cetyl caprate, 1
The amount of 0% carboxymethyl cellulose aqueous solution used was 12
The average particle size was 5 μm in the same manner as in Example 1 except that the amount was 0 parts.
Thermochromic granules were obtained.

This granular material exhibits a blue color at room temperature (approximately 25°C), but
The color began to fade at 9°C and became colorless at about 31°C. Upon subsequent cooling, color development started at about 25°C and turned blue again at about 23°C. The hysteresis width H8 at this time was 6°C.

When this granular material is heated to about 38℃ and then cooled, it becomes about 18℃.
It remained colorless up to 16°C and turned blue upon further cooling at about 16°C. The hysteresis width ΔH in this case was 13°C.

Reference Example 2 30 parts of titanium oxide and 70 parts of aminoalkyd cocondensation resin [trade name: BECCOSOL M-7610-50, manufactured by Dainippon Ink & Chemicals, Ltd.] were mixed with aromatic hydrocarbon [trade name:
Paint I was prepared by diluting 40 parts of Tsurupetz #100 (manufactured by Esso Kagaku ■) with a mixed solvent of 5 parts of isopropyl alcohol and 5 parts of butyl glycol.

15 parts of thermochromic granules obtained in Example 2, 1 part of Glow Yellow MF2G, alkyd resin [trade name: Beccosol J-544-55-P.

Manufactured by Dainippon Ink Chemical Industry ■ 65 parts and melamine resin [
Product name: varnish - Perbeckamin G-871-60, manufactured by Dainippon Ink & Chemicals Co., Ltd.] 20 parts, Tsurupetz #100
Paint by diluting with 25 parts and 5 parts of cellosolve acetate■
It was created.

Paint (2) was prepared by diluting 100 parts of Beccosol M-7610-50 with 45 parts of Tsurupetz #100 and 5 parts of butyl glycol.

Paint I was applied electrostatically to the surface of a toy (mini car) whose surface had been treated with zinc phosphate, and after being left for 5 minutes, it was heated to 110°C.
A white layer was formed by heat treatment for 0 minutes. Next, paint (2) was applied to the entire surface of the white layer, left to stand for 5 minutes, and then heat treated at 120° C. for 10 minutes to form a discolored layer. Further, paint (2) was applied to the surface of the discoloration layer, left for 5 minutes, and then heat treated at 130° C. for 10 minutes to form a transparent protective layer.

This minicar is green at room temperature (approximately 25 degrees Celsius) and is approximately 29
The blue color began to disappear at 31°C and turned yellow at about 31°C. Upon subsequent cooling, a blue color began to develop at about 25°C and turned green again at about 23°C. When this minicar was heated to 38°C and then cooled, it remained yellow until about 18°C and turned green at about 16°C.

That is, this miniature car has poor hysteresis when heated up to about 31°C, but by heating it up to 38°C, one or both of green and yellow can be enjoyed in the temperature range of 18 to 29°C.

Example 3 Using 2 parts of Oico dye (B-63), 5 parts of bisphenol A, 20 parts of β-naphthyl palmitate, and 10 parts of cecyl myristate, the amount of 50% methylolated melamine aqueous solution used was 20 parts, and 10 parts of 50% methylolated melamine aqueous solution. Thermochromic granules having an average particle size of 5 μm were obtained in the same manner as in Example 1, except that the amount of the % carboxymethyl cellulose aqueous solution used was 100 parts.

This granular material exhibited a blue color at room temperature, began to lose color at 60°C when heated, and became colorless at 62°C.

Upon subsequent cooling, color development started at 57°C and turned blue again at 55°C. Therefore, the normal hysteresis width H8 of this particulate material is 5°C.

Hysteresis width Δ when this granular material is heated to 70℃
At H-12℃, from 50℃ to 48℃, it changes from colorless to blue.
Hysteresis width ΔH-14,5 when heated to 75℃
℃, changes from colorless to blue at 47.5℃ → 45℃,
Hysteresis width ΔH when further heated to 80℃ = 16
The color changed from colorless to blue at 46°C to 44°C.

Reference Example 3 Ceramic transfer paper with a landscape picture printed on it was painted on the side of a ceramic mug. Next, 10 parts of the thermochromic granular material obtained in Example 3, a conventional thermochromic granular material [colorless above 48°C, yellow below 46°C, trade name: Chromic Color 5-47] First Yellow, ■Made by Matsui Shiki Kagaku Kogyo Co., Ltd.] 10 parts, Epoxy resin [Product name: Epico-4828, manufactured by Yuka Shell Epoxy ■] 50 minutes, Hardening agent [Product name: Epome) B-001, Yuka Shell Made of epoxy ■ 30 parts, silane coupling.

agent [product name: Silicone 5H-6020, manufactured by Toshi Silicone ■] and anti-sagging agent [product name: Talen 7200-2]
0, manufactured by Kyoeisha Yushi Co., Ltd.] was uniformly mixed to make a printing ink, and printed on the lawn part of the landscape painting using a screen plate,
Heat treatment was performed at 150°C for 10 minutes.

When coffee is poured into this mug, if the temperature of the coffee is between 62 and 70°C, as the coffee cools, the grass will change from colorless to blue to green (Figure 3-1), 75
When the temperature is around ℃, the color changes from colorless to green (Figure 3-2).
When the temperature was 80°C or higher, the color changed from colorless to yellow to green (Figure 3-3).

By using this mug, you can enjoy the different changes in color while also knowing the temperature of the coffee when poured.

[Brief explanation of drawings]

FIG. 1 is a graph showing the characteristics of the composition of the present invention. FIG. 2 is a graph showing the relationship between the heating temperature width (Δt) and the increase width of the hysteresis width (ΔHt). FIG. 3 is a graph showing the change in color due to temperature of a mug to which the composition of the present invention is applied. (That's all) Figure 3-1 Δt0C M

Claims (4)

[Claims] (1) (a) A colorless or very light-colored leuco dye, (b) a color-developing substance that develops color when it comes into contact with the leuco dye, and (c) heating in the coexistence of the leuco dye and the color-developing substance. Then, the dye contains an alkyl ester of aliphatic carboxylic acid and an ester having at least one aromatic ring in the molecule, which decolorizes the dye, and Δt°C from the complete decoloring temperature (T_2) of the coloring density-temperature curve. A thermochromic composition whose hysteresis width expands by ΔHt when exposed to high temperatures. (2) Claim (1) in which ΔHt also increases as Δt increases
Composition of. (3) When 5℃<Δt<(200-T_2)℃, ΔHt
is the maximum hysteresis width H_M_A_X, and Δt
The composition according to claim 1, wherein the hysteresis width remains constant at H_M_A_X at a temperature of (200-T_2)°C or higher. (4) Maximum hysteresis width H_M_A_X is 5℃<H_
The composition according to claim 3, wherein M_A_X<30°C.