JPH0516474B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to thermochromic compositions. Electron-donating color-forming organic compounds (hereinafter referred to as color formers), compounds that develop color by reacting with color formers (hereinafter referred to as color developers), and compounds that suppress the reaction between color formers and color developers (hereinafter referred to as desensitizers) Thermochromic colorants are known. Such a coloring agent is useful as an example of a temperature indicator because it produces a so-called thermochromic phenomenon in which the composition reversibly 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. As a result of various studies in view of the above-mentioned drawbacks of known thermochromic compositions, the present inventor found that when using 5-mercapto-1,2,3,4-tetrazole or a derivative thereof as a color developer, It has been found that the above-mentioned drawbacks are substantially eliminated. That is, the present invention provides (i) one part of at least one electron-donating color-forming organic compound; (ii) a compound having the general formula 5-mercapto- represented by [R represents hydrogen, an alkyl group having 1 to 8 carbon atoms, a phenyl group, or a (CH ₂ )nCOOH group (n represents an integer of 1 to 3)]
1,2,3,4-tetrazole or its derivative
0.1 to 100 parts, and (iii) alcohols, esters,
The present invention relates to a thermochromic composition containing 0.5 to 500 parts of at least one compound selected from the group consisting of ketones, ethers, acid amides, carboxylic acids, and hydrocarbons. 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. Fluoranes...3,6-diethoxyfluoran, 3-dimethylamino-6-methyl-7-chlorofluoran, 1,2-benz-6-diethylaminofluoran, 3-diethylamino-7-methoxyfluoran, etc. . Phenothiazines...benzoylleucomethylene blue, methylleucomethylene blue, ethylleucomethylene blue, methoxybenzoylleucomethylene blue, etc. Indolylphthalides...2-(phenyliminoethanedylidene)-3,3-dimethylindoline, etc. Spiropyrans...1,3,3-trimethyl-
Indolino-7′-chlor-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. Examples of 5-mercapto-1,2,3,4 tetrazole or its derivatives used as a color developer in the present invention include the following. 1H-5-mercapto-1,2,3,4-tetrazole, 1-methyl-5-mercapto-1,
2,3,4-tetrazole, 1-phenyl-5-
Mercapto-1,2,3,4-tetrazole, 1
-carboxymethyl-5-mercapto-1,2,
3,4-tetrazole, 1-ethyl-5-mercapto-1,2,3,4-tetrazole, 1-iso
-Propyl-5-mercapto-1,2,3,4-
Tetrazole, 1-butyl-5-mercapto-
1,2,3,4-tetrazole, 1-tolyl-
5-mercapto-1,2,3,4-tetrazole, 1-carboxyethyl-5-mercapto-
1,2,3,4-tetrazole and the like. As the desensitizer used in the present invention, those used in known thermochromic coloring 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, Pentaerythritol, etc. Esters...Lauryl caproate, octyl caprate, butyl laurate, dodecyl laurate, hexyl myristate, myristyl myristate, octyl palmitate, stearyl palmitate, butyl stearate, cetyl stearate, lauryl behenate, oleic acid Cetyl,
Butyl benzoate, phenyl benzoate, dibutyl sebatate, etc. Ketones...cyclohexanone, acetophenone, benzophenone, dimyristyl ketone, etc. Ethers: dilauryl ether, dicetyl ether, diphenyl ether, ethylene glycol monostearyl 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, etc. Acid amides...caprylic acid amide, capric acid amide, lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide,
Behenic acid amide, oleic acid amide, benzamide, etc. Hydrocarbons: aliphatic hydrocarbons such as octane, isooctane, decane, etc. Aromatic hydrocarbons such as benzene, toluene, xylene, etc. Alicyclic hydrocarbons such as cyclohexane, ethylcyclohexane, butylcyclohexane. A mixed solvent of the above sold as ligroin, volatile oil, gasoline, and kerosene. The ratio of color former: color developer: desensitizer in the present invention is usually 1:1/10 to 100:0.5 by weight.
It is about 500, more preferably 1:1/2~
The ratio is about 40:1 to 200. If the amount of the color developer is excessive, the reversible color changing 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 excessive, the coloring density will be low, whereas if it is insufficient, the color erasing property will be decreased. If necessary, pigments, extender pigments, etc. can be added to the thermochromic composition of the present invention to adjust color development. 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 present invention is used as a liquid colorant for writing instrument ink, stamp ink, etc., it is sufficient to select a desensitizer that can serve as a solvent for a specific color former and color developer, and dissolve it in this desensitizer. Also, coloring agent,
The color developer and desensitizer may be dissolved in a solvent. Furthermore, when used as a crayon or pastel solid colorant, the color former, color developer, and desensitizer are heated and melted, uniformly dispersed, and then molded into a predetermined shape.
After uniformly dispersing the coloring agent, color developer, and desensitizer in an excipient such as microcrystalline wax, polyethylene, or polypropylene that has been cooled or heated and melted, it can be processed by pouring, injection, or extrusion. It is sufficient to mold it into a predetermined shape and cool it. According to the present invention, the following effects are achieved. (i) Since the color developer is non-toxic or has low toxicity, there are no restrictions on its uses. (ii) The thermochromic property is stable even after repeated use over a long period of time, and the color changes clearly at a specified temperature. Example 1 Crystal violet lactone (the following parts indicate parts by weight), 1 part 5-mercapto-1,2,3,4-tetrazole
2 parts were added to 30 parts of cetyl alcohol, heated and melted at 140°C, uniformly dispersed, poured into a mold, cooled and solidified to obtain a crayon-like solid colorant. This coloring agent was blue at 20°C, but when it was applied to paper and heated to 50°C, the color completely disappeared. This discoloration was reversible. Coloring agents of Examples 2 to 25 were prepared according to Example 1. The composition and physical properties are shown in Table 1. However, Examples 10, 13 to 15, 17 and 20 are liquid at room temperature.

【table】

【table】

[Table] Example 26 15 g of Epicote 828 (epoxy resin manufactured by Yuka Ciel) was added to 90 g of the composition obtained in Example 2.
The solution was dissolved at 0.degree. C. and forcedly stirred while being dropped into 300 g of an 8% aqueous gelatin solution to obtain Solution A. After that, dissolve 6 g of Epicure U (epoxy resin curing agent made by Yuka Ciel) in 40 c.c. of water and slowly drop it into liquid A. After that, keep the liquid temperature at 80 to 90°C. Stirring was carried out for about 2 to 3 hours, thereby obtaining an epoxy capsule slurry encapsulating the thermochromic composition. Example 27 Take 60g of the capsules obtained in Example 26, remove about half of the water, and add 10% PVA aqueous solution 25g.
g, 5 g of water, and 0.1 g of antifoaming agent were mixed and kneaded to prepare silk ink. Example 28 70 g of a 5% aqueous gelatin solution and 70 g of a 5% aqueous gum arabic solution were added and heated to 50°C, followed by forced stirring while adding 50 g of the thermochromic composition obtained in Example 6. Add 20% NaOH and PH
Adjust the temperature to 4.9, then lower the temperature to 45℃ and add water to 70℃.
Add g. After cooling to 5° C., 1 ml of 50% glutaraldehyde is added dropwise and stirred for 6 hours to obtain a gelatin capsule slurry containing the thermochromic composition. Example 29 The capsule liquid obtained in Example 28 was subjected to the same operation as in Example 27 to obtain silk ink.

Claims (1)

[Scope of Claims] 1 (i) At least one part of an electron-donating color-forming organic compound (ii) General formula [R is hydrogen, an alkyl group having 1 to 8 carbon atoms, a phenyl group, or a ( _CH2 )nCOOH group (n is 1 to 3
0.1 to 100 parts of 5-mercapto-1,2,3,4-tetrazole or its derivatives represented by (representing an integer of )] (iii) Alcohols, esters, ketones, ethers, acid amides A thermochromic composition containing 0.5 to 500 parts of at least one compound selected from the group consisting of , carboxylic acids, and hydrocarbons.