Reversible thermochromic microcapsule pigments

Abstract

The present application provides a reversible thermochromic microcapsule pigment which is easily changed to a colored state from a colorless state by heating at a temperature in a living environment temperature range or a temperature close to a daily life temperature, and is sensitively recovered to the colorless state again. The reversible thermochromic microcapsule pigment of the present application is formed by enclosing a reversible thermochromic composition in a microcapsule, the reversible thermochromic composition comprising (A) an electron-donating colored organic compound, (B) a 4-hydroxybenzoic acid ester compound represented by the following general formula (1) as an electron-accepting compound (in the formula, R represents a linear or branched alkyl group having 12 to 22 carbon atoms), (C) a chain hydrocarbon compound or the like as a reaction medium in which reversible electron transfer reactions based on the above (A) and (B) occur, (D) a linear dibasic acid compound having 3 to 22 carbon atoms, and (E) an aromatic hydrocarbon compound or the like having a melting point of 50°C or higher.

Description

Technical Field

[0001] This invention relates to reversible thermochromic microcapsule pigments. More specifically, it relates to reversible thermochromic microcapsule pigments that develop color upon heating from a decolorized state. Background Technology

[0002] A reversible thermochromic composition and a microcapsule pigment containing the reversible thermochromic composition have been disclosed previously. The reversible thermochromic composition consists of (A) an electron-donating and color-developing organic compound, (B) an electron-withdrawing compound, and (C) a reaction medium that enables the electron transfer reaction based on (A) and (B) to occur reversibly. By using hydroxybenzoic acid ester as component (B), it exhibits a color-changing behavior that is easily changed from a colorless state to a color-developing state by heating and then restored to a colorless state by cooling at temperatures close to or within the range of ambient living temperatures (see, for example, Patent Documents 1-4).

[0003] As for the above-mentioned reversible thermochromic composition, although it can exhibit a colored state by heating at a relatively low temperature, it sometimes takes time to return to a decolorized state, which makes it difficult to meet practical needs.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2013-159706

[0007] Patent Document 2: Japanese Patent Application Publication No. 2013-231138

[0008] Patent Document 3: Japanese Patent Application Publication No. 2017-14328

[0009] Patent Document 4: International Publication No. 2020 / 196073 Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] The inventors conducted in-depth research on reversible thermochromic compositions that develop color through heating from a colorless state. The results showed that by adding specific compounds to components (A), (B), and (C), reversible thermochromic microcapsule pigments containing the reversible thermochromic composition can be obtained. These reversible thermochromic compositions exhibit color-changing behavior at ambient temperatures close to daily living temperatures, readily changing from a colorless state to a color-developing state through heating, and then sensitively reverting to a colorless state. This completes the present invention.

[0012] Problem-solving methods

[0013] According to the present invention, the following invention is provided.

[0014] [1] A reversible thermochromic microcapsule pigment, which is formed by encapsulating a reversible thermochromic composition that changes from a decolorizing state to a color-developing state by heating and from a color-developing state to a decolorizing state by cooling, wherein the reversible thermochromic composition comprises:

[0015] (A) Electron-donating colorimetric organic compounds

[0016] (B) 4-hydroxybenzoic acid ester compounds represented by the following general formula (1) as electron-withdrawing compounds,

[0017] (C) A compound selected from chain hydrocarbons, alicyclic hydrocarbons, and halohydrocarbons, which serves as the reaction medium for reversibly enabling the electron transfer reactions based on (A) and (B).

[0018] (D) Straight-chain dicarboxylic acid compounds with 3–22 carbon atoms, and

[0019] (E) Compounds selected from alcohols, esters, ethers, ketones, amides and aromatic hydrocarbons with a melting point of 50°C or higher;

[0020]

[0021] In the formula, R represents a straight-chain or branched alkyl group with 12 to 22 carbon atoms.

[0022] [2] According to the reversible thermochromic microcapsule pigment of [1], the alkyl group of the hydroxybenzoate compound represented by the general formula (1) is a straight-chain alkyl group with 14 to 22 carbon atoms.

[0023] [3] According to the reversible thermochromic microcapsule pigment described in [1] or [2], the ratio of component (D) to component (A) is 0.1 to 1% by mass.

[0024] [4] The reversible thermochromic microcapsule pigment according to any one of [1] to [3] has (E) component in a ratio of 0.3 to 2% by mass to (A) component.

[0025] [5] The reversible thermochromic microcapsule pigment according to any one of [1] to [4] further comprises (F) an oligomer selected from styrene oligomers with a weight average molecular weight of 200 to 6000, terpene oligomers with a weight average molecular weight of 250 to 4000, and terpene phenolic oligomers with a weight average molecular weight of 200 to 2000.

[0026] [6] According to the reversible thermochromic microcapsule pigment described in [5], the mass ratio of component (D) to component (F) is 1.0:3.5 to 1.0:30.0.

[0027] Invention Effects

[0028] This invention provides a reversible thermochromic microcapsule pigment that exhibits reversible color-changing behavior, which can be easily changed from a colorless state to a color-developing state by heating at temperatures close to those in the living environment, and then sensitively restored to a colorless state. It can be applied to various fields such as teaching components, toys, and decorations. Detailed Implementation

[0029] This invention relates to reversible thermochromic microcapsule pigments formed by encapsulating a reversible thermochromic composition within microcapsules. First, the components incorporated in this reversible thermochromic composition will be described below.

[0030] (A)Ingredients

[0031] The reversible thermochromic composition used in this invention comprises an electron-donating chromogenic organic compound (hereinafter, sometimes referred to as component (A)). Component (A) is the color-determining component, which is a compound that donates electrons to an electron-withdrawing compound that acts as a chromogenic agent to produce color.

[0032] As component (A), examples include phthalide compounds, fluorane compounds, styrylquinoline compounds, diazarhodamine lactone compounds, pyridine compounds, quinazoline compounds, bisquinazoline compounds, etc., with phthalide compounds and fluorane compounds being preferred.

[0033] Examples of phthalide compounds include diphenylmethane phthalide compounds, phenylindolyl phthalide compounds, indolyl phthalide compounds, diphenylmethane aziridine phthalide compounds, phenylindolyl aziridine phthalide compounds, and their derivatives, with phenylindolyl aziridine phthalide compounds and their derivatives being preferred.

[0034] In addition, examples of fluorane compounds include, for example, aminofluorane compounds, alkoxyfluorane compounds, and their derivatives.

[0035] These compounds are exemplified below.

[0036] 3,3-Bis(p-dimethylaminophenyl)-6-dimethylaminophthalide,

[0037] 3-(4-Diethylaminophenyl)-3-(1-Ethyl-2-methylindole-3-yl)phthalide,

[0038] 3,3-Bis(1-n-butyl-2-methylindole-3-yl)phthalide,

[0039] 3,3-Bis(2-ethoxy-4-diethylaminophenyl)-4-azaphthalene,

[0040] 3-(2-ethoxy-4-diethylaminophenyl)-3-(1-ethyl-2-methylindole-3-yl)-4-azaphthalide,

[0041] 3-(2-hexyloxy-4-diethylaminophenyl)-3-(1-ethyl-2-methylindole-3-yl)-4-azaphthalide

[0042] 3-(2-ethoxy-4-(N-ethylanilino)phenyl)-3-(1-ethyl-2-methylindole-3-yl)-4-azaphthalide,

[0043] 3-(2-acetamido-4-diethylaminophenyl)-3-(1-propylindol-3-yl)-4-azaphthalide,

[0044] 3,6-bis(diphenylamino)fluorane,

[0045] 3,6-Dimethoxyfluorane,

[0046] 3,6-Di-n-Butoxyfluorane,

[0047] 2-Methyl-6-(N-ethyl-N-p-tolylamino)fluorane,

[0048] 3-Chloro-6-cyclohexylaminofluorane,

[0049] 2-Methyl-6-cyclohexylaminofluorane,

[0050] 2-(2-Chloroamino)-6-dibutylaminofluorane,

[0051] 2-(2-Chloroanilino)-6-di-n-butylaminofluorane,

[0052] 2-(3-trifluoromethylaniline)-6-diethylaminofluorane,

[0053] 2-(3-trifluoromethylaniline)-6-dipentylaminofluorane,

[0054] 2-(dibenzylamino)-6-diethylaminofluorane,

[0055] 2-(N-methylaniline)-6-(N-ethyl-N-p-tolylamino)fluorane,

[0056] 1,3-Dimethyl-6-diethylaminofluorane,

[0057] 2-Chloro-3-methyl-6-diethylaminofluorane,

[0058] 2-Aniline-3-methyl-6-diethylaminofluorane,

[0059] 2-Aniline-3-methoxy-6-diethylaminofluorane,

[0060] 2-Aniline-3-methyl-6-di-n-butylaminofluorane,

[0061] 2-Aniline-3-methoxy-6-di-n-butylaminofluorane,

[0062] 2-Dimethylamino-3-methyl-6-diethylaminofluorane,

[0063] 2-Aniline-3-methyl-6-(N-ethyl-N-p-tolylamino)fluorane,

[0064] 1,2-Benzo-6-diethylaminofluorane,

[0065] 1,2-Benzo-6-(N-ethyl-N-isobutylamino)fluorane,

[0066] 1,2-Benzo-6-(N-ethyl-N-isopentylamino)fluorane,

[0067] 2-(3-methoxy-4-dodecyloxystyryl)quinoline,

[0068] 2-(diethylamino)-8-(diethylamino)-4-methylspiro(5H-(1)benzopyrano(2,3-d)pyrimidin-5,1'(3'H)isobenzofuran)-3'-one,

[0069] 2-(di-n-butylamino)-8-(di-n-butylamino)-4-methylspiro(5H-(1)benzopyrano(2,3-d)pyrimidin-5,1'(3'H)isobenzofuran)-3'-one,

[0070] 2-(di-n-butylamino)-8-(diethylamino)-4-methylspiro(5H-(1)benzopyrano(2,3-d)pyrimidin-5,1'(3'H)isobenzofuran)-3'-one,

[0071] 2-(di-n-butylamino)-8-(N-ethyl-N-isopentylamino)-4-methylspiro(5H-(1)benzopyrano(2,3-d)pyrimidin-5,1'(3'H)isobenzofuran)-3'-one,

[0072] 2-(dibutylamino)-8-(dipentylamino)-4-methylspiro(5H-(1)benzopyrano(2,3-d)pyrimidin-5,1'(3'H)isobenzofuran)-3'-one,

[0073] 2-(dibutylamino)-8-(diphenylamino)-4-methylspiro(5H-(1)benzopyrano(2,3-d)pyrimidin-5,1'(3'H)isobenzofuran)-3'-one,

[0074] 4,5,6,7-Tetrachloro-3-(4-(dimethylamino)-2-methoxyphenyl)-3-(1-butyl-2-methyl-1H-indol-3-yl)-1(3H)-isobenzofuranone,

[0075] 4,5,6,7-Tetrachloro-3-(4-(diethylamino)-2-ethoxyphenyl)-3-(1-ethyl-2-methyl-1H-indol-3-yl)-1(3H)-isobenzofuranone,

[0076] 4,5,6,7-Tetrachloro-3-(4-(diethylamino)-2-ethoxyphenyl)-3-(1-pentyl-2-methyl-1H-indol-3-yl)-1(3H)-isobenzofuranone,

[0077] 4,5,6,7-Tetrachloro-3-[4-(diethylamino)-2-methylphenyl]-3-(1-ethyl-2-methyl-1H-indol-3-yl)-1(3H)-isobenzofuranone,

[0078] 3',6'-Bis(phenyl(2-methylphenyl)amino)-spiro[isobenzofuran-1(3H),9'-(9H)xanthon]-3-one,

[0079] 3',6'-Bis(phenyl(3-methylphenyl)amino)-spiro[isobenzofuran-1(3H),9'-(9H)xanthon]-3-one,

[0080] 3′,6′-bis(phenyl(3-ethylphenyl)amino)-spiro[isobenzofuran-1(3H),9′-(9H)xanthon]-3-one,

[0081] 2,6-Bis(2'-ethyloxyphenyl)-4-(4'-dimethylaminophenyl)pyridine,

[0082] 2,6-Bis(2′,4′-Diethyloxyphenyl)-4-(4′-Dimethylaminophenyl)pyridine,

[0083] 2-(4'-Dimethylaminophenyl)-4-methoxy-quinazolin,

[0084] 4,4'-(ethylenedioxy)-bis[2-(4-diethylaminophenyl)quinazolin] etc.

[0085] It should be noted that, as fluoranes, in addition to the above-mentioned compounds that have substituents on the phenyl group forming the xanthonium ring, there are also compounds that have substituents on both the phenyl group forming the xanthonium ring and the phenyl group forming the lactone ring (e.g., alkyl groups such as methyl, halogen groups such as chloro groups), which exhibit blue or black colors.

[0086] (B) Ingredients

[0087] The reversible thermochromic composition used in this invention comprises an electron-withdrawing compound (hereinafter, sometimes referred to as component (B)). Component (B) is a compound that accepts electrons from component (A) and functions as a color developer of component (A).

[0088] As component (B), hydroxybenzoate compounds represented by general formula (1) are used.

[0089]

[0090] In the formula, R represents a straight-chain or branched alkyl group with 12 to 22 carbon atoms.

[0091] The alkyl group R in hydroxybenzoate is a straight-chain or branched alkyl group with 12 to 22 carbon atoms. Systems with alkyl groups having fewer than 12 or more than 22 carbon atoms exhibit low crystallinity, thus failing to meet practical requirements. Furthermore, considering practical properties such as excellent color-changing characteristics and color concentration, straight-chain alkyl groups with 14 to 22 carbon atoms are preferred.

[0092] Examples of hydroxybenzoic acid esters include dodecyl 4-hydroxybenzoate, tridecyl 4-hydroxybenzoate, tetradecyl 4-hydroxybenzoate, pentadecyl 4-hydroxybenzoate, hexadecyl 4-hydroxybenzoate, heptadecanyl 4-hydroxybenzoate, octadecyl 4-hydroxybenzoate, nonadecanyl 4-hydroxybenzoate, eicosyl 4-hydroxybenzoate, dodecyl 4-hydroxybenzoate, and dodecyl 4-hydroxybenzoate.

[0093] (C) Components

[0094] The reversible thermochromic composition used in this invention comprises a reaction medium (hereinafter, sometimes referred to as component (C)) that enables the electron transfer reaction based on components (A) and (B) to occur reversibly. As component (C), a compound selected from chain hydrocarbons, alicyclic hydrocarbons, and halogenated hydrocarbons is used.

[0095] By using component (C), the desensitization effect on the color development caused by the reaction of components (A) and (B) is small, which can effectively improve the color change behavior and color concentration caused by heating.

[0096] It should be noted that the hydroxybenzoate as component (B) tends to have higher crystallinity with a larger number of carbon atoms in the alkyl group. By adding component (C), the hydroxybenzoate with high crystallinity can be used at the color change temperature in the low-temperature region.

[0097] Examples of the aforementioned chain hydrocarbons include (i) saturated chain hydrocarbons such as pentadecane, hexadecane, heptadecanane, octadecane, nonadecanane, eicosane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecanane, octadecane, nonadecanane, and triacontane, and (ii) unsaturated chain hydrocarbons such as 1-pentadecanene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecanene, 1-eicosene, 1-dodecene, 1-tetadecanene, 1-tetadecanene, 1-tetadecanene, 1-tetadecanene, 1-tetadecanene, 1-tetadecanene, 1-tetadecanene, 1-tetadecanene, 1-tetadecanene, 1-tetadecanene, 1-tetadecanene, 1-tetadecanene, 1-tetadecanene, and 1-tetadecanene.

[0098] Examples of alicyclic hydrocarbons include cyclooctane, cyclododecane, n-pentadecylcyclohexane, n-octadecylcyclohexane, n-nonadecylcyclohexane, and decahydronaphthalene.

[0099] Examples of halogenated hydrocarbons include 1-bromodecane, 1-bromoundecane, 1-bromododecane, 1-bromotridecane, 1-bromotetradecane, 1-chlorotetradecane, 1-bromopentadecanane, 1-bromohexadecane, 1-chlorohexadecane, 1-iodohexadecane, 1-bromoheptadecane, 1-bromooctadecane, 1-chlorooctadecane, 1-iodooctadecane, 1-bromoeicosane, 1-chloroeicosane, 1-bromodocosahexadecane, and 1-chlorodocosahexadecane.

[0100] (D) Components

[0101] The reversible thermochromic composition used in this invention comprises a straight-chain dicarboxylic acid compound having 3 to 22 carbon atoms (hereinafter, sometimes referred to as component (D)). Examples of component (D) include malonic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, nonadecanoic acid, eicosanoic acid, and docosanoic acid.

[0102] By adding component (D), the polarity of the compound selected from chain hydrocarbons, alicyclic hydrocarbons, and halogenated hydrocarbons, which serves as the reaction medium, changes. Therefore, the solubility of component (B) in the reaction medium decreases, and the crystallization of component (B) gradually proceeds. Thus, if a reversible thermochromic microcapsule pigment containing a reversible thermochromic composition that cools from a colored state to a decolorization induction temperature during the cooling process is placed, it will decolorize sensitively.

[0103] (E) Components

[0104] The reversible thermochromic composition used in this invention comprises a compound selected from alcohols, esters, ethers, ketones, acid amides, and aromatic hydrocarbons with a melting point of 50°C or higher (hereinafter, sometimes referred to as component (E)). As the reversible thermochromic composition used in this invention, during the cooling process from the colored state, component (D) causes component (B) to crystallize and decolorize, but component (E) can further promote crystallization, resulting in more sensitive decolorization.

[0105] Examples of the aforementioned alcohols include hexadecane-1-ol, heptadecane-1-ol, octadecane-1-ol, nonadecane-1-ol, eicosane-1-ol, docosane-1-ol, tetradecane-1-ol, hexadecane-1-ol, octadecane-1-ol, triacontane-1-ol, etc.

[0106] Examples of the aforementioned esters include eicosyl laurate, behenyl laurate, tetraalkyl laurate, hexaalkyl laurate, octadecyl laurate, cetyl myristate, stearyl myristate, eicosyl myristate, behenyl myristate, tetraalkyl myristate, hexaalkyl myristate, octadecyl myristate, myristyl palmitate, cetyl palmitate, stearyl palmitate, eicosyl palmitate, behenyl palmitate, tetraalkyl palmitate, hexaalkyl palmitate, octadecyl palmitate, cetyl stearate, stearyl stearate, eicosyl stearate, behenyl stearate, tetraalkyl stearate, hexaalkyl stearate, and octadecyl stearate. Ester, Decyl eicosanoate, Undecyl eicosanoate, Tridecyl eicosanoate, Myristyl eicosanoate, Cetyl eicosanoate, Stearyl eicosanoate, Eicosanoate, Dodecyl eicosanoate, Tetradecyl eicosanoate, Hexadecyl eicosanoate, Octyl eicosanoate, Methyl behenate, Hexyl behenate, Octyl behenate, Behenate Decyl behenate, undecyl behenate, lauryl behenate, tridecyl behenate, myristyl behenate, cetyl behenate, stearyl behenate, eicosyl behenate, behenate, tetradecyl behenate, hexadecyl behenate, octadecyl behenate, distearate oxalate, di(eicosyl) oxalate, behenate oxalate, succinic acid Distearate, eicosyl succinate, behenyl succinate, distearate glutarate, di(eicosyl) glutarate, behenyl glutarate, dimyristyl adipate, diceryl adipate, distearate, eicosyl adipate, behenyl adipate, diceryl succinate, distearate, di(eicosyl) succinate, behenyl succinate, myristyl azelate, diceryl azelate, distearate, eicosyl azelate, behenyl azelate, dimyristyl sebacate, diceryl sebacate, distearate, di(eicosyl) sebacate, di(eicosyl) sebacate, dibehenyl sebacate, 1,14-tetramethyldicarboxylic acid di(tetrazyl) ester, 1,14-tetramethyldicarboxylic acid dimyristyl ester 1,14-Tetramethyldicarboxylate dicetyl, 1,14-Tetramethyldicarboxylate dipalmityl, 1,14-Tetramethyldicarboxylate distearate, 1,14-Tetramethyldicarboxylate di(eicoalkyl), 1,14-Tetramethyldicarboxylate dibenzyl, 1,16-Hexadecyldicarboxylate dilaurate, 1,16-Hexadecyldicarboxylate di(tridecyl), 1,16-Hexadecyldicarboxylate dimyristyl, 1,16-Hexadecyldicarboxylate dicetyl, 1,16-Hexadecyldicarboxylate dipalmityl, 1,16-Hexadecyldicarboxylate distearate, 1,16-Hexadecyldicarboxylate di(eicoalkyl), 1,16-Hexadecyldicarboxylate dibenzyl, 1,1,18-Octadecyl dicarboxylate, 1,18-Octadecyl dicarboxylate dilaurate, 1,18-Octadecyl dicarboxylate di(tridecyl) ester, 1,18-Octadecyl dicarboxylate dimyristyl ester, 1,18-Octadecyl dicarboxylate dicetyl ester, 1,18-Octadecyl dicarboxylate dipalmityl ester, 1,18-Octadecyl dicarboxylate distearate, 1,18-Octadecyl dicarboxylate di(eicoyl) ester, 1,18-Octadecyl dicarboxylate dibenzyl ester, 1,20-Eicosyl dicarboxylate didecrate, 1,20-Eicosyl dicarboxylate dilaurate, 1,20-Eicosyl dicarboxylate di(tridecyl) ester, 1, 2,0-Eicosemethylene dicarboxylate dimyristyl ester, 1,2,0-Eicosemethylene dicarboxylate dicetyl ester, 1,2,0-Eicosemethylene dicarboxylate dipalmityl ester, 1,2,0-Eicosemethylene dicarboxylate distearate, 1,2,0-Eicosemethylene dicarboxylate di(eicoalkyl) ester, 1,2,0-Eicosemethylene dicarboxylate dibehenyl ester, trimyristate glyceryl ester, tripalmitate glyceryl ester, tristearate glyceryl ester, tri(nonadecanoyl) glyceryl ester, hexanoate cholesterol ester, caprylate cholesterol ester, decanoate cholesterol ester, undecanoate cholesterol ester, laurate cholesterol ester, myristate cholesterol ester, palmitate cholesterol ester, stearate cholesterol ester, eicosanoate cholesterol ester, behenate cholesterol ester, etc.

[0107] Examples of the aforementioned ethers include pentadecyl ether, dihexadecyl ether, dioctadecyl ether, di(eicosyl) ether, and di(eicosyl) ether.

[0108] Examples of the aforementioned ketones include dioctyl ketone, dinonyl ketone, di(undecyl) ketone, di(tridecyl) ketone, di(pentadecanyl) ketone, di(heptadecanyl) ketone, di(nonadecanyl) ketone, phenyl octyl ketone, phenyl undecyl ketone, phenyl tridecyl ketone, phenyl pentadecyl ketone, and phenyl heptadecanyl ketone.

[0109] Examples of the aforementioned acid amides include hexamamide, heptadecamide, octamide, nonanamide, decamide, undecylamide, lauramide, tridecylamide, myristamide, palmitamide, stearamide, eicosamide, docosamide, hexacosamide, and octacosamide.

[0110] Examples of aromatic hydrocarbons mentioned above include dodecylbenzene, biphenyl, ethylbiphenyl, 4-benzylbenzene, phenyltolylmethane, diphenylethane, 1,3-diphenylbenzene, dibenzyltoluene, methylnaphthalene, 2,7-diisopropylnaphthalene, methyltetrahydronaphthalene, and naphthylphenylmethane.

[0111] (F)Ingredients

[0112] The reversible thermochromic composition of the present invention comprises components (A), (B), (C), (D) and (E), and may further comprise an oligomer selected from styrene oligomers with a weight average molecular weight of 200 to 6000, terpene oligomers with a weight average molecular weight of 250 to 4000, and terpene phenolic oligomers with a weight average molecular weight of 200 to 2000 (hereinafter, sometimes referred to as component (F)).

[0113] By including component (F) in the reversible thermochromic composition of the present invention, the polarity of component (C) changes, and the solubility of component (B) in the reaction medium containing component (F) decreases, thereby further promoting the crystallinity of component (B). As a result, the reversible thermochromic microcapsule pigment encapsulating the reversible thermochromic composition, which cools from a colored state to a decolorization induction temperature during cooling, is more readily and sensitively decolorized upon placement. That is, component (F) has the effect of enhancing the effect of component (D).

[0114] When the weight-average molecular weight of styrene oligomers is less than 200, the solubility of component (B) in the reaction medium is not easily reduced, and there is a tendency for the crystallization of component (B) itself to be difficult. In addition, when the weight-average molecular weight of styrene oligomers exceeds 6000, the dissolution of component (F) into component (C) becomes difficult, and the desired effect is easily obtained.

[0115] Furthermore, when the weight-average molecular weight of terpene oligomers is less than 2500, the solubility of component (B) in the reaction medium is not easily reduced, and there is a tendency for the crystallization of component (B) itself to be difficult. Conversely, when the weight-average molecular weight of terpene oligomers exceeds 4000, the dissolution of component (F) into component (C) becomes difficult, making it easier to obtain the desired effect.

[0116] Furthermore, when the weight-average molecular weight of terpene phenol oligomers is below 200, the solubility of component (B) in the reaction medium is not easily reduced, and there is a tendency for the crystallization of component (B) itself to be difficult. Conversely, when the weight-average molecular weight of terpene phenol oligomers exceeds 2000, the dissolution of component (F) into component (C) becomes difficult, making it easier to obtain the desired effect.

[0117] It should be noted that the weight-average molecular weight was determined by GPC (gel permeation chromatography).

[0118] Examples of the aforementioned styrene oligomers include low molecular weight polystyrene, styrene-α-methylstyrene copolymers, α-methylstyrene polymers, and copolymers of α-methylstyrene and vinyltoluene.

[0119] As a low molecular weight polystyrene, products manufactured by Sanyo Chemical Industries, Ltd., under trade names such as HIMER SB-75 (weight average molecular weight 2000) and HIMER ST-95 (weight average molecular weight 4000) can be used.

[0120] As a styrene-α-methylstyrene copolymer, it can be manufactured by Ryukaku Harcoulis Co., Ltd., with trade names such as Picolastic A5 (weight-average molecular weight 317) and Picolastic A75 (weight-average molecular weight 917).

[0121] As the α-methylstyrene polymer, it is possible to use the product of RIKEN HOLDINGS CO., LTD., trade name: Currys 3085 (weight average molecular weight 664), クリスタレックス3100 (weight average molecular weight 1020), クリスタレックス1120 (weight average molecular weight 2420), etc.

[0122] As a copolymer of α-methylstyrene and vinyltoluene, it can be manufactured by Rikka Harcoulis Co., Ltd., under trade names such as Picotex LC (weight-average molecular weight 950), Picotex 100 (weight-average molecular weight 1740), and Picotex 120 (weight-average molecular weight 2500).

[0123] Examples of terpene oligomers include α-pinene polymers, β-pinene polymers, and d-limonene polymers.

[0124] As an α-pinene polymer, it can be manufactured by RIKEN Harcoulis Co., Ltd., under the trade name Picolite A115 (weight-average molecular weight 833).

[0125] As a β-pinene polymer, it can be manufactured by RIKEN Harcoulis Co., Ltd., under the trade name Picolite S115 (weight-average molecular weight 1710).

[0126] As a d-limonene polymer, it can be manufactured by RIKEN Harcoulis Co., Ltd., under the trade name Pico Rait C115 (weight-average molecular weight 902).

[0127] Terpene phenol oligomers are compounds or their hydrides formed by copolymerizing cyclic terpene monomers with phenols. Specifically, examples include α-pinene-phenol copolymers.

[0128] As α-pinene-phenol copolymers, they can be manufactured by Yasuharake Mikaru Co., Ltd., under trade names such as YS Polystar T145 (weight-average molecular weight 1050), YS Polystar T130 (weight-average molecular weight 900), YS Polystar T500 (weight-average molecular weight 500), and YS Polystar S145 (weight-average molecular weight 1050).

[0129] (F) Components can be used alone or in combination of two or more.

[0130] The reversible thermochromic microcapsule pigment of the present invention encapsulates a reversible thermochromic composition. This reversible thermochromic composition comprises components (A), (B), (C), (D), and (E). Furthermore, as one embodiment, the reversible thermochromic composition comprises components (A), (B), (C), (D), and (E). Additionally, as another embodiment, the reversible thermochromic composition comprises components (A), (B), (C), (D), (E), and (F).

[0131] The proportions of components (A), (B), (C), (D), and (E) are affected by color concentration, color change temperature, color change morphology, and the types of components. Generally, the component ratios that yield the desired characteristics are as follows: relative to 1 part by mass of component (A), component (B) is 0.1 to 50 parts by mass, preferably 0.5 to 20 parts by mass; component (C) is 1 to 200 parts by mass, preferably 5 to 100 parts by mass; component (D) is 0.1 to 1.0 parts by mass, preferably 0.3 to 0.7 parts by mass; and component (E) is 0.3 to 2 parts by mass, preferably 0.5 to 1.5 parts by mass.

[0132] In addition, when the (F) component is incorporated, the (F) component is typically 3.0 to 15 parts by mass relative to 1 part by mass of the (A) component, preferably in the range of 3 to 10 parts by mass.

[0133] Furthermore, by setting the mass ratio of component (D) to component (F) to be, for example, 1.0:3.5 to 1.0:30.0, preferably 1.0:3.5 to 1.0:20.0, and more preferably 1.0:3.5 to 1.0:15.0, the polarity of the compound serving as the reaction medium changes, and the crystallization of component (B) is made easier, resulting in more sensitive decolorization.

[0134] The above-mentioned reversible thermochromic composition is used encapsulated in microcapsules. This is because, even when in contact with acidic substances, alkaline substances, peroxides, or other chemically active substances or solvents, its function will not be reduced, and it can maintain thermal stability. Under various usage conditions, the reversible thermochromic composition maintains the same composition and can exert the same effect.

[0135] The reversible thermochromic microcapsule pigment containing the above-mentioned reversible thermochromic composition has a particle size of 0.1 to 100 μm, preferably 0.5 to 30 μm, and more preferably 1 to 20 μm, which satisfies practicality.

[0136] It should be noted that the particle size and average particle size were determined using the image-resolution particle size distribution measurement software "Macbeth" manufactured by Multitech Co., Ltd., which identified the area of ​​the particles. The projected area circle equivalent diameter (Heywood diameter) was calculated from the area of ​​the particle's area, and this value was used as the measured values ​​for the particle size and average particle size of particles with an equivalent volume of spherical mass. Alternatively, when the particle size of all or most particles exceeds 0.2 μm, the particle size and average particle size of particles with an equivalent volume of spherical mass can also be determined using a particle size distribution measuring device (manufactured by Becman Corporation, product name: Multisizer 4e) via the coefficient method.

[0137] Furthermore, the particle size and average particle size (median particle size) of the volume reference can also be measured using a laser diffraction / scattering particle size distribution measuring device (device name: LA-960V2, manufactured by Horiba Manufacturing Co., Ltd.), which is calibrated based on values ​​measured using a measuring device employing the Coulter method.

[0138] It should be noted that each component can be a mixture of two or more compounds, and light stabilizers can be added within the range that does not impair the function.

[0139] As the aforementioned light stabilizers, examples include ultraviolet absorbers, visible light absorbers, infrared absorbers, antioxidants, carotenoids, pigments, amines, phenols, nickel complexes, thioethers, and other singlet oxygen matting agents that prevent light degradation caused by the photoreaction of component (A), superoxide anionic matting agents such as dioxime protease complexes with cobalt and nickel, and ozone matting agents, etc., formulated in proportions of 0.3 to 24% by mass, preferably 0.8 to 16% by weight. Among these, systems in which the aforementioned ultraviolet absorbers are used in combination with antioxidants and / or singlet oxygen matting agents are particularly effective in improving lightfastness.

[0140] In addition, anti-aging agents, antistatic agents, polarity imparting agents, thixotropic imparting agents, defoamers, etc. can be added as needed to improve functionality.

[0141] Furthermore, it can be used in conjunction with conventional dyes (non-thermochromic).

[0142] Examples of conventional dyes and pigments include acid dyes, basic dyes, direct dyes, inorganic pigments, organic pigments, coloring resin pigments, and titanium dioxide.

[0143] The color-changing properties of reversible thermochromic compositions containing components (A), (B), (C), (D), and (E), or reversible thermochromic microcapsule pigments containing reversible thermochromic compositions containing components (A), (B), (C), (D), (E), and (F), are described below.

[0144] A reversible thermochromic composition that exhibits a decolorized state begins to develop color at a temperature from the color development onset temperature (T1) during heating, and becomes fully color-developed when it reaches the complete color development temperature (T2). The reversible thermochromic composition that cools to the decolorization induction temperature during the cooling process decolorizes when left to stand.

[0145] The aforementioned reversible thermochromic microcapsule pigments are dispersed in a medium containing an adhesive as a film-forming material. They can be used as reversible thermochromic materials such as inks and coatings. They can be formed into reversible thermochromic layers on supports such as paper, synthetic paper, fabric, flocked or brushed fabric, nonwoven fabric, synthetic leather, leather, plastic, glass, ceramics, wood, and stone by conventionally known methods, such as screen printing, offset printing, gravure printing, coating machine, pad printing, inkjet printing, transfer printing, brushing, spraying, electrostatic coating, electrodeposition coating, flow coating, roller coating, and dip coating, or dispersed in the support.

[0146] Furthermore, it can be used as a material formed by mixing thermoplastics in a molten state.

[0147] Example

[0148] Examples 1-20

[0149] The components used in the reversible thermochromic compositions of the present invention are shown in the following table.

[0150] It should be noted that the numbers in parentheses in the table represent parts by mass, and the numbers below representing the amount of compounding are all parts by mass.

[0151] Table 1

[0152]

[0153] Table 2

[0154]

[0155] Each reversible thermochromic composition was heated and melted to form a compatibilizer. Then, 30.0 parts of an aromatic isocyanate prepolymer (used as a wall membrane material) and 40.0 parts of a co-solvent were mixed to form a solution. This solution was then emulsified and dispersed in an 8% polyvinyl alcohol aqueous solution. While heating and stirring continuously, 2.5 parts of a water-soluble aliphatic modified amine were added, and stirring was continued to obtain a microcapsule suspension. The suspension was centrifuged to obtain reversible thermochromic microcapsule pigments (Examples 1-20).

[0156] For the above-mentioned reversible thermochromic microcapsule pigments, after preparing the following test samples, the color change temperature was determined by the following test method.

[0157] Test sample

[0158] A reversible thermochromic ink, formed by dispersing 40 parts of the above-mentioned reversible thermochromic microcapsule pigment in 60 parts of ethylene-vinyl acetate emulsion, was screen-printed onto high-quality paper, and the resulting print was used as the test sample.

[0159] Determination methods

[0160] The test samples prepared using the reversible thermochromic microcapsule pigments of Examples 1 to 20 were placed at the designated position on a colorimeter (TC-3600 type colorimeter, manufactured by Tokyo Denko). The samples were heated at a rate of 10°C / minute within a temperature range of 0°C to 60°C. After heating to 60°C, the samples were cooled to the decolorization induction temperature and left to decolorize.

[0161] In addition, after heating at a rate of 10°C / minute within a temperature range of 0°C to 60°C, the sample was placed at 15°C for 1 minute, and the brightness value was measured.

[0162] The color changes, color development start temperature (T1), full color development temperature (T2), brightness value at full color development temperature (T2), decolorization induction temperature, and brightness value immediately after being placed at 15°C for 1 minute are shown in the following table for each embodiment.

[0163] It should be noted that the smaller the brightness value in the table, the higher the concentration, and the larger the value, the lower the concentration.

[0164] Table 3

[0165]

[0166] Comparative Examples 1 to 4

[0167] The components used in the reversible thermochromic compositions are shown in the table below. It should be noted that the numbers in parentheses in the table represent parts by mass, and all numbers indicating the proportions below are parts by mass.

[0168] Table 4

[0169]

[0170] Each reversible thermochromic composition was heated and melted to form a compatibilizer. Then, 30.0 parts of an aromatic isocyanate prepolymer (used as a wall film material) and 40.0 parts of a cosolvent were mixed to form a solution. This solution was then emulsified and dispersed in an 8% polyvinyl alcohol aqueous solution. While heating and stirring continuously, 2.5 parts of a water-soluble aliphatic modified amine were added, and stirring was continued to obtain a microcapsule suspension. The suspension was centrifuged to obtain reversible thermochromic microcapsule pigments (Comparative Examples 1-4).

[0171] For the above-mentioned reversible thermochromic microcapsule pigments, after preparing the following test samples, the color change temperature was determined by the following test method.

[0172] Test sample

[0173] A reversible thermochromic ink, formed by dispersing 40 parts of the above-mentioned reversible thermochromic microcapsule pigment in 60 parts of ethylene-vinyl acetate emulsion, was screen-printed onto high-quality paper, and the resulting print was used as the test sample.

[0174] Determination methods

[0175] The test samples prepared using the reversible thermochromic microcapsule pigments of Comparative Examples 1 to 4 were placed at the specified position on a colorimeter (TC-3600 type colorimeter, manufactured by Tokyo Denko). The samples were heated at a rate of 10°C / minute within a temperature range of 0°C to 60°C.

[0176] After heating to 60°C, cool to the decolorization induction temperature and let it stand to decolorize.

[0177] In addition, after heating at a rate of 10°C / minute within a temperature range of 0°C to 60°C, the sample was placed at 15°C for 1 minute, and the brightness value was measured.

[0178] The color change, color development start temperature (T1), complete color development temperature (T2), brightness value at complete color development temperature (T2), decolorization induction temperature, and brightness value immediately after being placed at 15°C for 1 minute for each comparative example are shown in the table below.

[0179] Table 5

[0180]

[0181] Application Example 1

[0182] 30.0 parts of the microcapsule pigment containing the reversible thermochromic composition prepared in Example 1 were mixed in a color carrier consisting of 45.0 parts of acrylic resin emulsion, 1.0 part of defoamer, and 23.0 parts of diluent water, and filtered through an 180-mesh sieve to obtain a reversible thermochromic spray coating.

[0183] The above-mentioned spray coating is filled into a spray gun (0.6 mm in diameter) and applied to the entire surface of a white fabric (support). After drying, a reversible thermochromic layer is formed, resulting in a reversible thermochromic fabric.

[0184] Sew the above-mentioned fabric to make a swimsuit.

[0185] The swimsuits mentioned above turn blue when heated to above 45°C.

[0186] When the swimsuit is cooled to 18°C ​​and then left to stand, it turns white.

[0187] Application Example 2

[0188] A reversible thermochromic screen printing ink was prepared by comprising 30.0 parts of microcapsule pigment containing a reversible thermochromic composition, 2.0 parts of fluorescent pigment (pink), 50.0 parts of acrylic resin emulsion, 3.0 parts of defoamer, and 15.0 parts of turpentine emulsion prepared in Example 2.

[0189] Using the aforementioned reversible thermochromic screen printing ink, a reversible thermochromic layer is formed by screen printing on polyester taffeta, resulting in a reversible thermochromic sheet.

[0190] The reversible thermochromic sheet mentioned above turns purple when heated to above 48°C.

[0191] When the reversible thermochromic sheet is cooled to 26°C and then placed in the container, it turns pink.

[0192] Application Example 3

[0193] 50.0 parts of the microcapsule pigment containing the reversible thermochromic composition prepared in Example 3 were uniformly dispersed and mixed in 50.0 parts of linseed oil-based offset printing ink carrier to prepare reversible thermochromic offset printing ink.

[0194] The above-mentioned offset printing ink is used on high-quality paper for offset printing to form a reversible thermochromic layer, thus obtaining a reversible thermochromic film.

[0195] The above-mentioned sheet turns blue when heated to above 47°C.

[0196] When the reversible thermochromic sheet is cooled to 26°C and then placed in a container, it becomes colorless.

[0197] Application Example 4

[0198] In the reversible thermochromic epoxy ink prepared in Example 4, 33.3 parts of microcapsule pigment containing a reversible thermochromic composition, 66.4 parts of hard liquid epoxy resin, and 0.3 parts of defoamer were uniformly dispersed and mixed. Then, 20.0 parts of room temperature curing aliphatic polyamide were added and stirred to prepare the reversible thermochromic epoxy ink.

[0199] On the surface of a ceramic cup, the aforementioned reversible thermochromic epoxy ink is used for curved screen printing using a 100-mesh stainless steel screen. The ink is then heated and cured at 70°C for 60 minutes to form a reversible thermochromic layer, resulting in a reversible thermochromic cup.

[0200] The aforementioned reversible thermochromic cup turns blue when heated to above 47°C.

[0201] When the reversible thermochromic cup is cooled to 26°C and then placed in a container, it becomes colorless.

[0202] Application Example 5

[0203] A reversible thermochromic spray coating was prepared by mixing 10.0 parts of microcapsule pigment containing a reversible thermochromic composition prepared in Example 5, 1.0 part of fluorescent pigment (pink), and 45.0 parts of a 50% acrylic resin / xylene solution, 15.0 parts of xylene, 23.0 parts of methyl isobutyl ketone, and 6.0 parts of a polyisocyanate curing agent.

[0204] The reversible thermochromic spray coating is sprayed onto the entire micro electric vehicle to form a reversible thermochromic layer, thus obtaining a reversible thermochromic micro electric vehicle.

[0205] The reversible thermochromic micro electric vehicle turns purple when heated to above 47°C.

[0206] When the aforementioned reversible thermochromic mini electric vehicle is cooled to 25°C and then placed in a container, it turns pink.

[0207] Application Example 6

[0208] 50.0 parts of microcapsule pigment containing a reversible thermochromic composition prepared in Example 6, 0.04 parts of yellow pigment, 1000.0 parts of 12 nylon resin (melting point 178°C), and 10.0 parts of ultraviolet absorber were mixed, dispersed in a Henschel mixer, and then extruded to obtain reversible thermochromic 12 nylon resin granules (resin composition for reversible thermochromic molding).

[0209] The reversible thermochromic molding resin composition described above is used for melt spinning to obtain a reversible thermochromic filament as a molded body.

[0210] The aforementioned filaments were used to implant hair onto the doll's head.

[0211] When the above-mentioned filaments are heated to above 48°C, they exhibit a green color that is a mixture of blue and yellow.

[0212] After the filaments were cooled to 26°C, they turned yellow when left to stand.

[0213] Application Example 7

[0214] A reversible thermochromic spray coating was prepared by mixing 10.0 parts of microcapsule pigment containing a reversible thermochromic composition prepared in Example 7, 1.0 part of blue pigment, and 45.0 parts of a 50% acrylic resin / xylene solution, 15.0 parts of xylene, 23.0 parts of methyl isobutyl ketone, and 6.0 parts of a polyisocyanate curing agent.

[0215] The reversible thermochromic spray coating is sprayed onto the entire micro electric vehicle to form a reversible thermochromic layer, thus obtaining a reversible thermochromic micro vehicle.

[0216] The aforementioned reversible thermochromic microcar turns purple when heated to above 48°C.

[0217] When the aforementioned reversible thermochromic microcar is cooled to 26°C and then placed in a container, it turns blue.

[0218] Application Example 8

[0219] 50.0 parts of the microcapsule pigment containing the reversible thermochromic composition prepared in Example 8 were uniformly dispersed and mixed in 50.0 parts of linseed oil-based offset printing ink carrier to prepare reversible thermochromic offset printing ink.

[0220] The above-mentioned offset printing ink is used on high-quality paper for offset printing to form a reversible thermochromic layer, thus obtaining a reversible thermochromic film.

[0221] Frictional heat is generated by rubbing the sheet material with a SEBS friction tool. When heated to above 50°C, it turns blue.

[0222] When the reversible thermochromic sheet is cooled to 25°C and then placed, it turns white.

[0223] Application Example 9

[0224] 50.0 parts of the microcapsule pigment containing the reversible thermochromic composition prepared in Example 10 were uniformly dispersed and mixed in 50.0 parts of linseed oil-based offset printing ink carrier to prepare reversible thermochromic offset printing ink.

[0225] The above-mentioned offset printing ink is used on high-quality paper for offset printing to form a reversible thermochromic layer, thus obtaining a reversible thermochromic film.

[0226] When heated to above 57°C using an electric heating tool, the sheet turns blue.

[0227] After the reversible thermochromic sheet is cooled to 33°C, it turns white if left for a period of time.

[0228] Application Example 10

[0229] 50.0 parts of the microcapsule pigment containing the reversible thermochromic composition prepared in Example 12 were uniformly dispersed and mixed in 50.0 parts of linseed oil-based offset printing ink carrier to prepare reversible thermochromic offset printing ink.

[0230] The above-mentioned offset printing ink is used on high-quality paper for offset printing to form a reversible thermochromic layer, thus obtaining a reversible thermochromic film.

[0231] Frictional heat is generated by rubbing the sheet material with a SEBS friction tool. When heated to above 53°C, it turns blue.

[0232] When the reversible thermochromic sheet is cooled to 28°C and then placed in a container, it turns white.

[0233] Application Example 13

[0234] 50.0 parts of the microcapsule pigment containing the reversible thermochromic composition prepared in Example 16 were uniformly dispersed and mixed in 50.0 parts of linseed oil-based offset printing ink carrier to prepare reversible thermochromic offset printing ink.

[0235] The above-mentioned offset printing ink is used on high-quality paper for offset printing to form a reversible thermochromic layer, thus obtaining a reversible thermochromic film.

[0236] Frictional heat is generated by rubbing the sheet material with a SEBS friction tool. When heated to above 51°C, it turns pink.

[0237] When the reversible thermochromic sheet is cooled to 27°C and then placed in a container, it turns white.

[0238] Application Example 14

[0239] 50.0 parts of the microcapsule pigment containing the reversible thermochromic composition prepared in Example 17 were uniformly dispersed and mixed in 50.0 parts of linseed oil-based offset printing ink carrier to prepare reversible thermochromic offset printing ink.

[0240] The above-mentioned offset printing ink is used on high-quality paper for offset printing to form a reversible thermochromic layer, thus obtaining a reversible thermochromic film.

[0241] Frictional heat is generated by rubbing the sheet material with a SEBS friction tool. When heated to above 52°C, it turns pink.

[0242] After the reversible thermochromic sheet is cooled to 27°C, it turns white when left to stand.

Claims

1. A reversible thermochromic microcapsule pigment, formed by encapsulating a reversible thermochromic composition that changes from a decolorizing state to a color-developing state by heating and from a color-developing state to a decolorizing state by cooling, wherein the reversible thermochromic composition comprises: (A) Electron-donating colorimetric organic compounds, (B) 4-hydroxybenzoic acid esters represented by the following general formula (1) as electron-withdrawing compounds, (C) A compound selected from chain hydrocarbons, alicyclic hydrocarbons, and halogenated hydrocarbons, which serves as the reaction medium for reversibly enabling the electron transfer reactions based on (A) and (B). (D) Straight-chain dicarboxylic acid compounds with 3-22 carbon atoms, and (E) terphenyl; Relative to 1 part by mass of component (A), component (B) is 0.1 to 50 parts by mass, component (C) is 1 to 200 parts by mass, component (D) is 0.1 to 1.0 parts by mass, and component (E) is 0.3 to 2 parts by mass. In the formula, R represents a straight-chain or branched alkyl group with 12 to 22 carbon atoms.

2. The reversible thermochromic microcapsule pigment according to claim 1, wherein R in the general formula (1) is a straight-chain alkyl group having 14 to 22 carbon atoms.

3. The reversible thermochromic microcapsule pigment according to claim 1 or 2 further comprises (F) an oligomer selected from styrene oligomers with a weight average molecular weight of 200 to 6000, terpene oligomers with a weight average molecular weight of 250 to 4000, and terpene phenolic oligomers with a weight average molecular weight of 200 to 2000.

4. The reversible thermochromic microcapsule pigment according to claim 3, wherein the mass ratio of component (D) to component (F) is 1.0:3.5 to 1.0:30.0.

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