Reversible thermochromic composition and reversible thermochromic microcapsule pigment containing the same

Abstract

To provide a reversible thermochromic composition that has excellent contrast between a colored state and a non-colored state and shows excellent light resistance for a long time and a reversible thermochromic microcapsule pigment having the same encapsulated therein.SOLUTION: A reversible thermochromic composition includes a combination of (a) an electron-donating colorable organic compound and (b) a compound having a specific structure as an electron-accepting compound, and (c) a reaction medium that causes an electron exchange reaction between the components (a) and (b) to occur reversibly in a specific temperature range. There is also provided a reversible thermochromic microcapsule pigment having the same encapsulated therein.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a reversible thermochromic composition and a reversible thermochromic microcapsule pigment encapsulating the same. More specifically, the present invention relates to a reversible thermochromic composition that becomes discolored in a temperature range equal to or higher than its high-temperature discoloration point and becomes colored in a temperature range equal to or lower than its low-temperature discoloration point, and a reversible thermochromic microcapsule pigment encapsulating the same. [Background technology]

[0002] Conventionally, a reversible thermochromic composition that changes color from a colored state to a decolored state has been disclosed, which contains an electron-donating organic color-forming compound, an electron-accepting compound, and a reaction medium that reversibly causes an electron donating / accepting reaction between the electron-donating organic color-forming compound and the electron-accepting compound in a specific temperature range as essential components. For example, Patent Document 1 discloses the above-mentioned reversible thermochromic composition, and in particular discloses that a developer that is an electron-accepting compound has a specific structure, either alone or in combination of two or more.

[0003] The reversible thermochromic composition is required to have high density in the colored state, low density in the decolorized state, and excellent contrast.Furthermore, it is required to have excellent light resistance over a long period of time, that is, to suppress a decrease in color density even when exposed to light for a long period of time. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2002-53853 A Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made based on the background technology as described above, and aims to provide a reversible thermochromic composition that has a high density in a colored state, a low density in a decolorized state, and excellent light resistance over a long period of time, and a reversible thermochromic microcapsule pigment encapsulating the same. [Means for solving the problem]

[0006] The reversible thermochromic composition according to the present invention comprises: (a) an electron-donating color-forming organic compound; (b) a combination of a compound represented by formula (I) and a compound represented by formula (II) as an electron accepting compound; (c) a reaction medium that causes a reversible electron donor / donor reaction between the components (a) and (b) in a specific temperature range; and Including the law of nature, The mass ratio of the compound represented by the formula (I):the compound represented by the formula (II) is 1:0.2 to 1:4. do. [ka] (In the formula, R 11 is a branched alkyl group having 3 to 6 carbon atoms, R 12 teeth, Hydroxy group and N11 is 1 and N12 is 1 Yes the law of nature, Hydroxy groups are present at the 2nd and 4th positions of the benzene ring. ( [ka] (In the formula, R 21 is a hydrogen atom, or methyl group and R 22 teeth, Branched alkyl group with 5 to 9 carbon atoms or phenyl group and 、 n 23 and n24, respectively 0 Yes the law of nature, The hydroxyl group is located at the 4-position of each benzene ring. (

[0007] The reversible thermochromic microcapsule pigment according to the present invention contains the above-mentioned reversible thermochromic composition therein. The reversible thermochromic liquid composition according to the present invention comprises the above-mentioned reversible thermochromic microcapsule pigment and a vehicle. The reversibly thermochromic solid molding for coating according to the present invention comprises the above-mentioned reversibly thermochromic microcapsule pigment and an excipient. The reversible thermochromic molding resin composition according to the present invention comprises the above-mentioned reversible thermochromic microencapsulated pigment and a molding resin. The reversible thermochromic laminate of the present invention comprises a support and a reversible thermochromic layer containing the above-mentioned reversible thermochromic microencapsulated pigment. The writing implement according to the present invention contains a writing implement ink comprising a reversible thermochromic microencapsulated pigment and a vehicle. Effect of the Invention

[0008] The present invention can provide a reversible thermochromic composition that has a high density in a colored state, a low density in a decolorized state, excellent contrast between the colored state and the decolorized state, and excellent light resistance over a long period of time, and a reversible thermochromic microcapsule pigment encapsulating the same. [Brief description of the drawings]

[0009] [Figure 1] 1 is a graph illustrating hysteresis characteristics in a color density-temperature curve of a heat-discolorable, reversible thermochromic composition. [Diagram 2] 1 is a graph illustrating hysteresis characteristics in a color density-temperature curve of a heat-discolorable, reversible thermochromic composition having color memory properties. [Diagram 3] 1 is a graph illustrating hysteresis characteristics in a color density-temperature curve of a reversible thermochromic composition that develops color upon heating. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The reversible thermochromic composition of the present invention includes a reversible thermochromic composition of a heat-discolorable type (discolored by heating and colored by cooling) that contains at least three essential components: (i) an electron-donating color-forming organic compound, (ii) an electron-accepting compound, and (iii) a reaction medium that determines the temperature at which the color-forming reaction of components (i) and (ii) occurs. As the reversible thermochromic composition, a reversible thermochromic composition of the heat-discoloring type (discolored by heating and colored by cooling) having a relatively small hysteresis width (ΔH) (ΔH=1 to 7°C), which is described in JP-B-51-44706, JP-B-51-44707, JP-B-1-29398, etc., can be used, which discolors around a certain temperature (discoloration point), exhibits a discolored state in a temperature range above the high-temperature discoloration point, and a colored state in a temperature range below the low-temperature discoloration point, and of the two states, only one specific state exists in the room temperature range, and the other state is maintained while the heat or cold required to express that state is applied, but returns to the state it exhibits in the room temperature range when the application of heat or cold is removed (see Figure 1).

[0011] In addition, a reversible thermochromic composition of the heat-discoloring type (discolored by heating and colored by cooling) that exhibits a large hysteresis width (ΔH=8-70°C) as described in JP-B-4-17154, JP-A-7-179777, JP-A-7-33997, JP-A-8-39936, JP-A-2005-1369, etc., and in which the shape of the curve plotting the change in color density due to temperature change follows a path that is significantly different when the temperature is increased from the lower side of the color-discoloring temperature range and when the temperature is decreased from the higher side of the color-discoloring temperature range, and which has color memory in a specific temperature range [a temperature range between a color-discoloring onset temperature t2 and a color-discoloring onset temperature t3 (a substantially two-phase maintaining temperature range)] and is in a colored state in a temperature range below a complete color-discoloring temperature t1 or in a color-discolored state in a high temperature range above a complete color-discoloring temperature t4 (see FIG. 2).

[0012] Components (A), (B) and (C) will be specifically described below.

[0013] Component (A), that is, the electron-donating organic color-forming compound, is the component that determines the color, and is a compound that develops color by donating electrons to component (B), which is a color developer.

[0014] Examples of the electron-donating color-forming organic compound include phthalide compounds, fluoran compounds, styrinquinoline compounds, diazarhodamine lactone compounds, pyridine compounds, quinazoline compounds, and bisquinazoline compounds. Of these, pyridine compounds, quinazoline compounds, and bisquinazoline compounds are preferred.

[0015] Examples of the phthalide compound include a diphenylmethane phthalide compound, a phenylindolyl phthalide compound, an indolyl phthalide compound, a diphenylmethane azaphthalide compound, a phenylindolyl azaphthalide compound, and derivatives thereof. Among these, the phenylindolyl azaphthalide compound and derivatives thereof are preferred. Examples of the fluoran compound include aminofluoran compounds, alkoxyfluoran compounds, and derivatives thereof.

[0016] Examples of compounds that can be used as component (a) are given below. 3,3-bis(4-dimethylaminophenyl)-6-dimethylaminophthalide, 3-(4-diethylaminophenyl)-3-(1-ethyl-2-methylindol-3-yl)phthalide, 3,3-bis(1-n-butyl-2-methylindol-3-yl)phthalide, 3,3-bis(2-ethoxy-4-diethylaminophenyl)-4-azaphthalide, 3-(2-ethoxy-4-diethylaminophenyl)-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide, 3-(2-n-hexyloxy-4-diethylaminophenyl)-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide, 3-[2-ethoxy-4-(N-ethylanilino)phenyl]-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide, 3-(2-acetamido-4-diethylaminophenyl)-3-(1-propyl-2-methylindol-3-yl)-4-azaphthalide, 3,6-bis(diphenylamino)fluoran, 3,6-bis(N-phenyl-Np-tolylamino)fluoran, 3,6-dimethoxyfluoran, 3,6-di-n-butoxyfluoran, 2-methyl-6-(N-ethyl-Np-tolylamino)fluoran, 3-chloro-6-cyclohexylaminofluoran, 2-methyl-6-cyclohexylaminofluoran, 2-chloroamino-6-di-n-butylaminofluoran, 2-(2-chloroanilino)-6-di-n-butylaminofluoran, 2-(3-trifluoromethylanilino)-6-diethylaminofluoran, 2-(3-trifluoromethylanilino)-6-di-n-pentylaminofluoran, 2-dibenzylamino-6-diethylaminofluoran, 2-N-methylanilino-6-(N-ethyl-Np-tolylamino)fluoran, 1,3-dimethyl-6-diethylaminofluoran, 2-chloro-3-methyl-6-diethylaminofluoran, 2-anilino-3-methyl-6-diethylaminofluoran, 2-anilino-3-methoxy-6-diethylaminofluoran, 2-anilino-3-methyl-6-di-n-butylaminofluoran, 2-anilino-3-methoxy-6-di-n-butylaminofluoran, 2-xylidino-3-methyl-6-diethylaminofluoran, 2-anilino-3-methyl-6-(N-ethyl-Np-tolylamino)fluoran, 6-diethylamino-1,2-benzofluoran, 6-(N-ethyl-N-isobutylamino)-1,2-benzofluoran, 6-(N-ethyl-N-isopentylamino)-1,2-benzofluoran, 2-(3-methoxy-4-dodecoxystyryl)quinoline, 2-Diethylamino-8-diethylamino-4-methylspiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-di-n-butylamino-8-di-n-butylamino-4-methylspiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-Di-n-butylamino-8-diethylamino-4-methylspiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-Di-n-butylamino-8-(N-ethyl-N-isoamylamino)-4-methylspiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-di-n-butylamino-8-di-n-pentylamino-4-methylspiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 4,5,6,7-tetrachloro-3-(4-dimethylamino-2-methoxyphenyl)-3-(1-n-butyl-2-methyl-1H-indol-3-yl)-1(3H)-isobenzofuranone, 4,5,6,7-tetrachloro-3-(4-diethylamino-2-ethoxyphenyl)-3-(1-ethyl-2-methyl-1H-indol-3-yl)-1(3H)-isobenzofuranone, 4,5,6,7-tetrachloro-3-(4-diethylamino-2-ethoxyphenyl)-3-(1-n-pentyl-2-methyl-1H-indol-3-yl)-1(3H)-isobenzofuranone, 4,5,6,7-tetrachloro-3-(4-diethylamino-2-methylphenyl)-3-(1-ethyl-2-methyl-1H-indol-3-yl)-1(3H)-isobenzofuranone, 3',6'-bis[phenyl(2-methylphenyl)amino]spiro[isobenzofuran-1(3H),9'-[9H]xanthen]-3-one, 3',6'-bis[phenyl(3-methylphenyl)amino]spiro[isobenzofuran-1(3H),9'-[9H]xanthen]-3-one, 3',6'-bis[phenyl(3-ethylphenyl)amino]spiro[isobenzofuran-1(3H),9'-[9H]xanthen]-3-one, 2,6-bis(2′-ethyloxyphenyl)-4-(4′-dimethylaminophenyl)pyridine, 2,6-bis(2′,4′-diethyloxyphenyl)-4-(4′-dimethylaminophenyl)pyridine, 2-(4′-dimethylaminophenyl)-4-methoxyquinazoline, 4,4'-Ethylenedioxy-bis[2-(4-diethylaminophenyl)quinazoline]

[0017] In addition, the fluorans may be compounds having a substituent on the phenyl group forming the xanthene ring, or may be compounds that have a substituent on the phenyl group forming the xanthene ring and also have a substituent (e.g., an alkyl group such as a methyl group, or a halogen atom such as a chlorine atom) on the phenyl group forming the lactone ring, and that exhibit a blue or black color.

[0018] Component (b), ie, an electron accepting compound, is a compound that accepts electrons from component (a) and functions as a developer for component (a). The component (b) is a combination of a compound represented by formula (I) and a compound represented by formula (II).

[0019] The compound represented by formula (I) is: [ka] During the ceremony, R 11 and R 12 each independently represents a hydroxy group, a linear or branched alkoxy group having 1 to 9 carbon atoms, a linear or branched alkyl group having 1 to 10 carbon atoms which may be substituted with a fluorine atom, an alkenyl group having 2 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, or a halogen atom; Preferably, it is a hydroxy group or a linear or branched alkyl group having 1 to 8 carbon atoms. More preferably, it is a hydroxy group or a branched alkyl group having 3 to 6 carbon atoms. More preferred are a hydroxy group, an isobutyl group, a sec-butyl group, or a tert-butyl group. In the present invention, the aryl group also includes an alkyl-substituted aryl group (for example, a tolyl group). The same applies to the following aryl groups. n11 is an integer of 0 to 3, and preferably 1. n12 is an integer of 0 to 2, and preferably 1. In a more preferred embodiment, the hydroxyl groups are present at the 2-position (ortho-position) and 4-position (para-position) of the benzene ring.

[0020] Specific examples of (I) include the following: 2,4-dihydroxybenzophenone, 4,4′-dihydroxybenzophenone, 2,4-dihydroxy-2′-methylbenzophenone, 2,4-dihydroxy-3′-methylbenzophenone, 2,4-dihydroxy-4′-methylbenzophenone, 2,4-dihydroxy-4′-trifluoromethylbenzophenone, 2,4-dihydroxy-4′-ethylbenzophenone, 2,4-dihydroxy-4′-n-propylbenzophenone, 2,4-dihydroxy-4′-isopropylbenzophenone, 2,4-dihydroxy-4′-n-butylbenzophenone, 2,4-dihydroxy-4′-isobutylbenzophenone, 2,4-dihydroxy-4′-sec-butylbenzophenone, 2,4-dihydroxy-4′-tert-butylbenzophenone, 2,4-dihydroxy-4′-n-pentylbenzophenone, 2,4-dihydroxy-4′-n-hexylbenzophenone, 2,4-dihydroxy-4′-n-heptylbenzophenone, 2,4-dihydroxy-4′-n-octylbenzophenone, 2,4-dihydroxy-4′-n-decylbenzophenone, 2,4-dihydroxy-4′-phenylbenzophenone, 2,4-dihydroxy-4′-p-tolylbenzophenone, 2,4-dihydroxy-4′-(2-propenyl)benzophenone, 2,4-dihydroxy-4′-fluorobenzophenone, 2,4-dihydroxy-4′-chlorobenzophenone, 2,4-dihydroxy-2′,3′-dimethylbenzophenone, 2,4-dihydroxy-2′,4′-dimethylbenzophenone, 2,4-dihydroxy-2′,5′-dimethylbenzophenone, 2,4-dihydroxy-2′,6′-dimethylbenzophenone, 2,4-dihydroxy-3′,4′-dimethylbenzophenone, 2,4-dihydroxy-3′,5′-dimethylbenzophenone, 2,4-dihydroxy-2′,4′,6′-trimethylbenzophenone, 2,4-dihydroxy-2′-methoxybenzophenone, 2,4-dihydroxy-3′-methoxybenzophenone, 2,4-dihydroxy-4′-methoxybenzophenone, 2,4-dihydroxy-2′-ethoxybenzophenone, 2,4-dihydroxy-4′-ethoxybenzophenone, 2,4-dihydroxy-4′-n-propoxybenzophenone, 2,4-dihydroxy-4′-isopropoxybenzophenone, 2,4-dihydroxy-4′-n-butoxybenzophenone, 2,4-dihydroxy-4′-isobutoxybenzophenone, 2,4-dihydroxy-4′-n-pentyloxybenzophenone, 2,4-dihydroxy-4′-n-hexyloxybenzophenone, 2,4-dihydroxy-4′-n-heptyloxybenzophenone, 2,4-dihydroxy-4′-n-octyloxybenzophenone, 2,4-dihydroxy-4′-n-nonyloxybenzophenone, 2,4-dihydroxy-2′,3′-dimethoxybenzophenone, 2,4-dihydroxy-2′,4′-dimethoxybenzophenone, 2,4-dihydroxy-2′,5′-dimethoxybenzophenone, 2,4-dihydroxy-2′,6′-dimethoxybenzophenone, 2,4-dihydroxy-3′,4′-dimethoxybenzophenone, 2,4-dihydroxy-3′,5′-dimethoxybenzophenone, 2,4-dihydroxy-3′,4′-diethoxybenzophenone, 2,4-dihydroxy-2′,3′,4′-trimethoxybenzophenone, 2,4-dihydroxy-2′,3′,6′-trimethoxybenzophenone, 2,4-dihydroxy-3′,4′,5′-trimethoxybenzophenone, 2,4-Dihydroxy-3',4',5'-triethoxybenzophenone

[0021] The compound represented by formula (II) is as follows: [ka] During the ceremony, R 21 represents a hydrogen atom, a linear or branched alkyl group having 1 to 17 carbon atoms which may be substituted with a fluorine atom, or an aryl group having 6 to 10 carbon atoms, and is preferably a hydrogen atom or a methyl group. R 22 is a branched alkyl group having 5 to 17 carbon atoms which may be substituted by a fluorine atom (wherein a methylene (-CH2-) group in the alkyl group may be replaced by an oxy (-O-) group, a carbonyl (-CO-) group, or an imino (-NH-) group), or an aryl group having 6 to 10 carbon atoms; Preferably, it is a branched alkyl group having 5 to 9 carbon atoms or a phenyl group. More preferred is a branched alkyl group having 6 to 8 carbon atoms, or a phenyl group. However, R 21 and R 22 and R may together form a ring, and in the case of forming a ring, preferably form a cyclohexane ring which may be substituted by a methyl group. 21 and R 22 In one preferred embodiment, the ring is not formed. R 23 and R 24 each independently represents a linear or branched alkyl group having 1 to 4 carbon atoms which may be substituted by a fluorine atom or a hydroxy group, an alkenyl group having 2 to 4 carbon atoms, an aryl group having 6 to 10 carbon atoms, or a halogen atom, and is preferably a linear or branched alkyl group having 1 to 4 carbon atoms (more preferably a methyl group), or a halogen atom (more preferably a fluorine atom). n23 and n24 each independently represent 0 to 2, preferably 0 or 1, and more preferably 0. In a further preferred embodiment, the hydroxy group is present at the 4-position (para-position) of the benzene ring.

[0022] Specific examples of (II) include the following: 1,1-bis(4-hydroxyphenyl)-3-methylpentane, 1,1-bis(4-hydroxyphenyl)-2,3-dimethylpentane, 1,1-bis(4-hydroxyphenyl)-2-ethylbutane, 1,1-bis(4-hydroxyphenyl)-2-ethylhexane, 1,1-bis(4-hydroxyphenyl)-3,7-dimethyloctane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane, 1-phenyl-1,1-bis(4-hydroxyphenyl)methane, 1-p-tolyl-1,1-bis(4-hydroxyphenyl)methane, 2,2-bis(4-hydroxyphenyl)-6,10,14-trimethylpentadecane, 1-phenyl-1,1-bis(4-hydroxyphenyl)ethane, 1-p-tolyl-1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl) n-butylpropionate, 2,2-bis(4-hydroxyphenyl)-tert-butylpropionate, 2,2-bis(4-hydroxyphenyl)-4-methylhexane, 2,2-bis(4-hydroxyphenyl)-3,4-dimethylhexane, 2,2-bis(4-hydroxyphenyl)-3-ethylpentane, 2,2-bis(4-hydroxyphenyl)-3-ethylheptane, 2,2-bis(4-hydroxyphenyl)-4,8-dimethylnonane, 2,2-bis(3-fluoro-4-hydroxyphenyl)-4-methylhexane, 2,2-bis(4-hydroxyphenyl)-1,1,1-trifluoro-4-methylhexane, 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, 3,3-bis(4-hydroxyphenyl)oxindole, 3,3-bis(4-hydroxy-3-methylphenyl)oxindole, 1,1-Bis(3-phenyl-4-hydroxyphenyl)cyclohexane

[0023] By combining the compound represented by formula (I) and the compound represented by formula (II) as the component (B), the properties of each compound can be utilized to provide a reversible thermochromic composition having excellent light resistance over a long period of time. Specifically, even after being exposed to light for a long period of time, the decrease in concentration can be suppressed.

[0024] In the compound represented by formula (I), n11 and n12 are each preferably 1, and R 11 is a linear or branched alkyl group having 1 to 8 carbon atoms, and R 12 are hydroxy groups, and the hydroxy groups are present at the 2-position (ortho position) and 4-position (para position) of the benzene ring. More preferably, n11 and n12 are each 1, and R 11 is a branched alkyl group having 3 to 6 carbon atoms, and R 12 is a hydroxy group, and the hydroxy group is present at the 2-position (ortho position) and 4-position (para position) of the benzene ring. More preferably, n11 and n12 are each 1, and R 11 is an isobutyl group, a sec-butyl group, or a tert-butyl group, and R 12 is a hydroxy group, and these compounds have hydroxy groups at the 2nd (ortho) and 4th (para) positions of the benzene ring.

[0025] The compound represented by formula (II) is preferably R 21 is a hydrogen atom or a methyl group, and R 22 is a branched alkyl group having 5 to 9 carbon atoms or a phenyl group, n23 and n24 are each 0, and a hydroxy group is present at the 4-position (para position) of the benzene ring. 21 is a hydrogen atom or a methyl group, and R 22 is a branched alkyl group having 6 to 8 carbon atoms or a phenyl group, n23 and n24 are each 0, and a hydroxy group is located at the 4-position (para-position) of the benzene ring. That is, in the compound represented by formula (I), n11 and n12 are each 1, and R 11 is an isobutyl group, a sec-butyl group, or a tert-butyl group, and R 12 is a hydroxy group, and the hydroxy groups are located at the 2-position (ortho position) and 4-position (para position) of the benzene ring. Compounds represented by formula (II) include R 21 is a hydrogen atom or a methyl group, and R 22 is a branched alkyl group having 6 to 8 carbon atoms or a phenyl group, n23 and n24 are each 0, and a hydroxy group is present at the 4-position (para-position) of the benzene ring.

[0026] The mass ratio of the compound represented by formula (I): the compound represented by formula (II) is preferably in the range of 1:0.1 to 1:5, more preferably 1:0.2 to 1:4. By setting the mass ratio of the compound represented by formula (I) to the compound represented by formula (II) within the above range, it becomes easy to obtain a reversible thermochromic composition having a large difference between the colored density and the decolored density, i.e., an excellent contrast between the colored state and the decolored state.

[0027] The component (iii) of the reaction medium that reversibly induces an electron donor-recipient reaction between the components (a) and (b) in a specific temperature range will now be described. Examples of the component (c) include alcohols, esters, ketones, ethers, and acid amides. When the reversible thermochromic composition of the present invention is applied to microencapsulation and secondary processing, compounds having 10 or more carbon atoms are preferably used in order to stably retain the composition in the capsule, since low molecular weight compounds will evaporate out of the capsule when subjected to high heat treatment.

[0028] As the alcohols, aliphatic monohydric saturated alcohols having 10 or more carbon atoms are effective, such as decyl alcohol, undecyl alcohol, dodecyl alcohol, tridecyl alcohol, tetradecyl alcohol, pentadecyl alcohol, hexadecyl alcohol, heptadecyl alcohol, octadecyl alcohol, eicosyl alcohol, and docosyl alcohol.

[0029] As the esters, esters having 10 or more carbon atoms are effective, and any of the following can be used: esters obtained from any combination of a monovalent carboxylic acid having an aliphatic, alicyclic or aromatic ring and a monohydric alcohol having an aliphatic, alicyclic or aromatic ring; esters obtained from any combination of a polyvalent carboxylic acid having an aliphatic, alicyclic or aromatic ring and a monohydric alcohol having an aliphatic, alicyclic or aromatic ring; esters obtained from any combination of a monovalent carboxylic acid having an aliphatic, alicyclic or aromatic ring and a polyhydric alcohol having an aliphatic, alicyclic or aromatic ring; Examples of esters include esters obtained by any combination thereof, such as ethyl caprylate, octyl caprylate, stearyl caprylate, myristyl caprate, docosyl caprate, 2-ethylhexyl laurate, n-decyl laurate, 3-methylbutyl myristate, cetyl myristate, isopropyl palmitate, neopentyl palmitate, nonyl palmitate, cyclohexyl palmitate, n-butyl stearate, 2-methylbutyl stearate, 3,5,5-trimethylhexyl stearate, and stearate. n-Undecyl stearate, pentadecyl stearate, stearyl stearate, cyclohexylmethyl stearate, isopropyl behenate, hexyl behenate, lauryl behenate, behenyl behenate, cetyl benzoate, stearyl 4-tert-butylbenzoate, dimyristyl phthalate, distearyl phthalate, dimyristyl oxalate, dicetyl oxalate, dicetyl malonate, dilauryl succinate, dilauryl glutarate, diundecyl adipate, dilauryl azelate, di-(n-nonyl) sebacate ), 1,18-octadecylmethylenedicarboxylate dineopentyl, ethylene glycol dimyristate, propylene glycol dilaurate, propylene glycol distearate, hexylene glycol dipalmitate, 1,5-pentanediol distearate, 1,2,6-hexanetriol trimyristate, 1,4-cyclohexanediol didecyl, 1,4-cyclohexanedimethanol dimyristate, xylene glycol dicaprinate, and xylene glycol distearate.

[0030] Also effective are esters of saturated fatty acids and branched fatty alcohols, esters of unsaturated fatty acids or branched or substituted saturated fatty acids and branched fatty alcohols or fatty alcohols having 16 or more carbon atoms, and ester compounds selected from cetyl butyrate, stearyl butyrate, and behenyl butyrate. Examples of the ester compounds include 2-ethylhexyl butyrate, 2-ethylhexyl behenate, 2-ethylhexyl myristate, 2-ethylhexyl caprate, 3,5,5-trimethylhexyl laurate, 3,5,5-trimethylhexyl palmitate, 3,5,5-trimethylhexyl stearate, 2-methylbutyl caproate, 2-methylbutyl caprylate, 2-methylbutyl caprate, 1-ethylpropyl palmitate, 1-ethylpropyl stearate, 1-ethylpropyl behenate, laurate, 3,5,5-trimethylhexyl laurate, 3,5,5-trimethylhexyl palmitate, 3,5,5-trimethylhexyl stearate, 3,5,5-trimethylhexyl laurate, 3,5,5-trimethylhexyl stearate, 2-methylbutyl caproate, 2-methylbutyl caprylate, 2-methylbutyl caprate, 1-ethylpropyl palmitate, 1-ethylpropyl stearate, 1-ethylpropyl behenate, laurate, 3,5,5-trimethylhexyl ... 1-Ethylhexyl phosphate, 1-ethylhexyl myristate, 1-ethylhexyl palmitate, 2-methylpentyl caproate, 2-methylpentyl caprylate, 2-methylpentyl caprate, 2-methylpentyl laurate, 2-methylbutyl stearate, 2-methylbutyl stearate, 3-methylbutyl stearate, 1-methylheptyl stearate, 2-methylbutyl behenate, 3-methylbutyl behenate, 1-methylheptyl stearate, 1-methylheptyl behenate, 1-ethyl caproate 1-ethylpentyl palmitate, 1-methylpropyl stearate, 1-methyloctyl stearate, 1-methylhexyl stearate, 1,1-dimethylpropyl laurate, 1-methylpentyl caprate, 2-methylhexyl palmitate, 2-methylhexyl stearate, 2-methylhexyl behenate, 3,7-dimethyloctyl laurate, 3,7-dimethyloctyl myristate, 3,7-dimethyloctyl palmitate, 3,7-dimethyloctyl stearate, 3,7-dimethyloctyl behenate Examples of the stearate include 3,7-dimethyloctyl, stearyl oleate, behenyl oleate, stearyl linoleate, behenyl linoleate, 3,7-dimethyloctyl erucate, stearyl erucate, isostearyl erucate, cetyl isostearate, stearyl isostearate, 2-methylpentyl 12-hydroxystearate, 2-ethylhexyl 18-bromostearate, isostearyl 2-ketomyristate, 2-ethylhexyl 2-fluoromyristate, cetyl butyrate, stearyl butyrate, and behenyl butyrate.

[0031] Furthermore, in order to change color while exhibiting a large hysteresis characteristic with respect to the color density-temperature curve and to impart color memory depending on temperature change, exemplified are carboxylate compounds exhibiting a ΔT value (melting point-cloud point) of 5° C. or more and less than 50° C. as described in JP-B-4-17154, such as carboxylate esters containing a substituted aromatic ring in the molecule, esters of carboxylic acids containing an unsubstituted aromatic ring and aliphatic alcohols having 10 or more carbon atoms, carboxylate esters containing a cyclohexyl group in the molecule, esters of fatty acids having 6 or more carbon atoms and unsubstituted aromatic alcohols or phenols, esters of fatty acids having 8 or more carbon atoms and branched aliphatic alcohols, esters of dicarboxylic acids and aromatic alcohols or branched aliphatic alcohols, dibenzyl cinnamate, heptyl stearate, didecyl adipate, dilauryl adipate, dimyristyl adipate, dicetyl adipate, distearyl adipate, trilaurin, trimyristin, tristearin, dimyristin, distearin, etc.

[0032] Also effective are fatty acid ester compounds obtained from an aliphatic monohydric alcohol having an odd number of carbon atoms of 9 or more and an aliphatic carboxylic acid having an even number of carbon atoms, and fatty acid ester compounds having a total of 17 to 23 carbon atoms obtained from n-pentyl alcohol or n-heptyl alcohol and an aliphatic carboxylic acid having an even number of carbon atoms of 10 to 16. Examples of the fatty acid ester compound include n-pentadecyl acetate, n-tridecyl butyrate, n-pentadecyl butyrate, n-undecyl caproate, n-tridecyl caproate, n-pentadecyl caproate, n-nonyl caprylate, n-undecyl caprylate, n-tridecyl caprylate, n-pentadecyl caprylate, n-heptyl caprate, n-nonyl caprate, n-undecyl caprate, n-tridecyl caprate, n-pentadecyl caprate, n-pentyl laurate, n-heptyl laurate, n-nonyl laurate, n-undecyl laurate, n-tridecyl laurate, n-pentadecyl laurate, n-pentyl myristate, n-heptyl myristate, Examples include n-pentyl, n-nonyl myristate, n-undecyl myristate, n-tridecyl myristate, n-pentadecyl myristate, n-pentyl palmitate, n-heptyl palmitate, n-nonyl palmitate, n-undecyl palmitate, n-tridecyl palmitate, n-pentadecyl palmitate, n-nonyl stearate, n-undecyl stearate, n-tridecyl stearate, n-pentadecyl stearate, n-nonyl eicosanoate, n-undecyl eicosanoate, n-tridecyl eicosanoate, n-pentadecyl eicosanoate, n-nonyl behenate, n-undecyl behenate, n-tridecyl behenate, and n-pentadecyl behenate.

[0033] As the ketones, aliphatic ketones having a total carbon number of 10 or more are effective, and examples thereof include 2-decanone, 3-decanone, 4-decanone, 2-undecanone, 3-undecanone, 4-undecanone, 5-undecanone, 2-dodecanone, 3-dodecanone, 4-dodecanone, 5-dodecanone, 2-tridecanone, 3-tridecanone, 2-tetradecanone, 2-pentadecanone, 8-pentadecanone, 2-hexadecanone, 3-hexadecanone, 9-heptadecanone, 2-pentadecanone, 2-octadecanone, 2-nonadecanone, 10-nonadecanone, 2-eicosanone, 11-eicosanone, 2-heneicosanone, 2-docosanone, laurone, stearone, and the like. Further, aryl alkyl ketones having a total carbon number of 12 to 24, for example, n-octadecanophenone, n-heptadecanophenone, n-hexadecanophenone, n-pentadecanophenone, n-tetradecanophenone, 4-n-dodecaacetophenone, n-tridecanophenone, 4-n-undecanoacetophenone, n-laurophenone, 4-n-decanoacetophenone, n-undecanophenone, 4-n-nonylacetophenone, n-decanophenone, 4-n-octylacetophenone, n ... Examples of acetophenone include 4-n-heptylacetophenone, n-octanophenone, 4-n-hexylacetophenone, 4-n-cyclohexylacetophenone, 4-tert-butylpropiophenone, n-heptaphenone, 4-n-pentylacetophenone, cyclohexyl phenyl ketone, benzyl-n-butyl ketone, 4-n-butylacetophenone, n-hexanophenone, 4-isobutylacetophenone, 1-acetonaphthone, 2-acetonaphthone, and cyclopentyl phenyl ketone.

[0034] As the ethers, aliphatic ethers having a total of 10 or more carbon atoms are effective, and examples thereof include dipentyl ether, dihexyl ether, diheptyl ether, dioctyl ether, dinonyl ether, didecyl ether, diundecyl ether, didodecyl ether, ditridecyl ether, ditetradecyl ether, dipentadecyl ether, dihexadecyl ether, dioctadecyl ether, decanediol dimethyl ether, undecanediol dimethyl ether, dodecanediol dimethyl ether, tridecanediol dimethyl ether, decanediol diethyl ether, and undecanediol diethyl ether.

[0035] Examples of acid amides include acetamide, propionic acid amide, butyric acid amide, caproic 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, caproic acid anilide, caprylic acid anilide, capric acid anilide, lauric acid anilide, myristic acid anilide, palmitic acid anilide, stearic acid anilide, behenic acid anilide, oleic acid anilide, erucic acid anilide, and N-methyl caproic acid anilide. amide, caprylic acid N-methylamide, capric acid N-methylamide, lauric acid N-methylamide, myristic acid N-methylamide, palmitic acid N-methylamide, stearic acid N-methylamide, behenic acid N-methylamide, oleic acid N-methylamide, erucic acid N-methylamide, lauric acid N-ethylamide, myristic acid N-ethylamide, palmitic acid N-ethylamide, stearic acid N-ethylamide, oleic acid N-ethylamide, lauric acid N-butylamide, myristic acid N-butylamide, palmitic acid N-butylamide, stearic acid N-ethylamide Thearic acid N-butylamide, oleic acid N-butylamide, lauric acid N-octylamide, myristic acid N-octylamide, palmitic acid N-octylamide, stearic acid N-octylamide, oleic acid N-octylamide, lauric acid N-dodecylamide, myristic acid N-dodecylamide, palmitic acid N-dodecylamide, stearic acid N-dodecylamide, oleic acid N-dodecylamide, dilauric acid amide, dimyristic acid amide, dipalmitic acid amide, distearic acid amide, dioleic acid amide, trilauric ... Rimyristic acid amide, tripalmitic acid amide, tristearic acid amide, trioleic acid amide, succinic acid amide, adipic acid amide, glutaric acid amide, malonic acid amide, azelaic acid amide, maleic acid amide, succinic acid N-methylamide, adipic acid N-methylamide, glutaric acid N-methylamide, malonic acid N-methylamide, azelaic acid N-methylamide, succinic acid N-ethylamide, adipic acid N-ethylamide, glutaric acid N-ethylamide, malonic acid N-ethylamide, azelaic acid N-ethylamide, succinic acid N-butylamide,Examples include adipic acid N-butylamide, glutaric acid N-butylamide, malonic acid N-butylamide, adipic acid N-octylamide, and adipic acid N-dodecylamide.

[0036] Furthermore, the component (iii) may be a compound represented by the following formula (1). [ka] [In the formula, R1 represents a hydrogen atom or a methyl group, m represents an integer of 0 to 2, and either X1 or X2 is -(CH2) n OCOR2 or (CH2) n COOR2, the other represents a hydrogen atom, n represents an integer of 0 to 2, R2 represents an alkyl or alkenyl group having 4 or more carbon atoms, Y1 and Y2 each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a methoxy group, or a halogen atom, and r and p each independently represent an integer of 1 to 3. Of the compounds represented by formula (1), it is preferable that R1 is a hydrogen atom, since a reversible thermochromic composition having a wider hysteresis width can be obtained, and it is even more preferable that R1 is a hydrogen atom and m is 0. Among the compounds represented by formula (1), a compound represented by the following formula (2) is more preferred. [ka] (In the formula, R represents an alkyl group or alkenyl group having 8 or more carbon atoms, preferably an alkyl group having 10 to 24 carbon atoms, and more preferably an alkyl group having 12 to 22 carbon atoms.) Examples of the compound represented by formula (2) include 4-benzyloxyphenylethyl octanoate, 4-benzyloxyphenylethyl nonanoate, 4-benzyloxyphenylethyl decanoate, 4-benzyloxyphenylethyl undecanoate, 4-benzyloxyphenylethyl dodecanoate, 4-benzyloxyphenylethyl tridecanoate, 4-benzyloxyphenylethyl tetradecanoate, 4-benzyloxyphenylethyl pentadecanoate, 4-benzyloxyphenylethyl hexadecanoate, 4-benzyloxyphenylethyl heptadecanoate, and 4-benzyloxyphenylethyl octadecanoate.

[0037] Furthermore, the component (iii) may be a compound represented by the following formula (3). [ka] (In the formula, R represents an alkyl or alkenyl group having 8 or more carbon atoms, m and n each independently represent an integer of 1 to 3, and X and Y each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom.) Examples of the compound represented by formula (3) include 1,1-diphenylmethyl octanoate, 1,1-diphenylmethyl nonanoate, 1,1-diphenylmethyl decanoate, 1,1-diphenylmethyl undecanoate, 1,1-diphenylmethyl dodecanoate, 1,1-diphenylmethyl tridecanoate, 1,1-diphenylmethyl tetradecanoate, 1,1-diphenylmethyl pentadecanoate, 1,1-diphenylmethyl hexadecanoate, 1,1-diphenylmethyl heptadecanoate, and 1,1-diphenylmethyl octadecanoate.

[0038] Furthermore, the component (iii) may be a compound represented by the following formula (4). [ka] (In the formula, X represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a methoxy group, or a halogen atom, m represents an integer of 1 to 3, and n represents an integer of 1 to 20.) Examples of the compound represented by formula (4) include a diester of malonic acid and 2-[4-(4-chlorobenzyloxy)phenyl]ethanol, a diester of succinic acid and 2-(4-benzyloxyphenyl)ethanol, a diester of succinic acid and 2-[4-(3-methylbenzyloxy)phenyl]ethanol, a diester of glutaric acid and 2-(4-benzyloxyphenyl)ethanol, a diester of glutaric acid and 2-[4-(4-chlorobenzyloxy)phenyl]ethanol, a diester of adipic acid and 2-(4-benzyloxyphenyl)ethanol, a diester of pimelic acid and 2-(4-benzyloxyphenyl)ethanol, a diester of suberic acid and 2-(4-benzyloxyphenyl)ethanol, a diester of suberic acid and 2-[4-(3-methyl Examples of the diester include a diester of suberic acid and 2-[4-(4-chlorobenzyloxy)phenyl]ethanol, a diester of suberic acid and 2-[4-(2,4-dichlorobenzyloxy)phenyl]ethanol, a diester of azelaic acid and 2-(4-benzyloxyphenyl)ethanol, a diester of sebacic acid and 2-(4-benzyloxyphenyl)ethanol, a diester of 1,10-decanedicarboxylic acid and 2-(4-benzyloxyphenyl)ethanol, a diester of 1,18-octadecanedicarboxylic acid and 2-(4-benzyloxyphenyl)ethanol, and a diester of 1,18-octadecanedicarboxylic acid and 2-[4-(2-methylbenzyloxy)phenyl]ethanol.

[0039] Furthermore, the component (iii) may be a compound represented by the following formula (5). [ka] (In the formula, R represents an alkyl or alkenyl group having 1 to 21 carbon atoms, and n represents an integer of 1 to 3.) Examples of the compound represented by formula (5) include a diester of 1,3-bis(2-hydroxyethoxy)benzene and capric acid, a diester of 1,3-bis(2-hydroxyethoxy)benzene and undecanoic acid, a diester of 1,3-bis(2-hydroxyethoxy)benzene and lauric acid, a diester of 1,3-bis(2-hydroxyethoxy)benzene and myristic acid, a diester of 1,4-bis(hydroxymethoxy)benzene and butyric acid, a diester of 1,4-bis(hydroxymethoxy)benzene and isovaleric acid, and a diester of 1,4-bis(2-hydroxyethoxy)benzene and acetic acid. Examples of such esters include diesters of 1,4-bis(2-hydroxyethoxy)benzene and propionic acid, diesters of 1,4-bis(2-hydroxyethoxy)benzene and valeric acid, diesters of 1,4-bis(2-hydroxyethoxy)benzene and caproic acid, diesters of 1,4-bis(2-hydroxyethoxy)benzene and caprylic acid, diesters of 1,4-bis(2-hydroxyethoxy)benzene and capric acid, diesters of 1,4-bis(2-hydroxyethoxy)benzene and lauric acid, and diesters of 1,4-bis(2-hydroxyethoxy)benzene and myristic acid.

[0040] Furthermore, the component (iii) may be a compound represented by the following formula (6). [ka] (In the formula, X represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom; m represents an integer of 1 to 3; and n represents an integer of 1 to 20.) Examples of the compound represented by formula (6) include a diester of succinic acid and 2-phenoxyethanol, a diester of suberic acid and 2-phenoxyethanol, a diester of sebacic acid and 2-phenoxyethanol, a diester of 1,10-decanedicarboxylic acid and 2-phenoxyethanol, and a diester of 1,18-octadecanedicarboxylic acid and 2-phenoxyethanol.

[0041] Furthermore, the component (iii) may be a compound represented by the following formula (7). [ka] (In the formula, R represents any one of an alkyl group having 4 to 22 carbon atoms, a cycloalkylalkyl group, a cycloalkyl group, and an alkenyl group having 4 to 22 carbon atoms; X represents any one of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and a halogen atom; and n represents 0 or 1.) Examples of the compound represented by formula (7) include decyl 4-phenylbenzoate, lauryl 4-phenylbenzoate, myristyl 4-phenylbenzoate, cyclohexylethyl 4-phenylbenzoate, octyl 4-biphenylacetate, nonyl 4-biphenylacetate, decyl 4-biphenylacetate, lauryl 4-biphenylacetate, myristyl 4-biphenylacetate, tridecyl 4-biphenylacetate, pentadecyl 4-biphenylacetate, cetyl 4-biphenylacetate, cyclopentyl 4-biphenylacetate, cyclohexylmethyl 4-biphenylacetate, and hexyl 4-biphenylacetate.

[0042] Furthermore, the component (iii) may be a compound represented by the following formula (8). [ka] (In the formula, R represents an alkyl group having 3 to 18 carbon atoms or an aliphatic acyl group having 3 to 18 carbon atoms; X represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 or 2 carbon atoms, or a halogen atom; Y represents a hydrogen atom or a methyl group; and Z represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 or 2 carbon atoms, or a halogen atom.) Examples of the compound represented by formula (8) include phenoxyethyl 4-butoxybenzoate, phenoxyethyl 4-pentyloxybenzoate, phenoxyethyl 4-tetradecyloxybenzoate, an ester of phenoxyethyl 4-hydroxybenzoate with dodecanoic acid, and dodecyl ether of phenoxyethyl vanillate.

[0043] Furthermore, the component (iii) may be a compound represented by the following formula (9). [ka] (In the formula, R represents any one of an alkyl group having 4 to 22 carbon atoms, an alkenyl group having 4 to 22 carbon atoms, a cycloalkylalkyl group, and a cycloalkyl group; X represents any one of a hydrogen atom, an alkyl group, an alkoxy group, and a halogen atom; Y represents any one of a hydrogen atom, an alkyl group, an alkoxy group, and a halogen atom; and n represents 0 or 1.) Examples of the compound represented by formula (9) include the benzoate ester of octyl 4-hydroxybenzoate, the benzoate ester of decyl 4-hydroxybenzoate, the 4-methoxybenzoate ester of heptyl 4-hydroxybenzoate, the 2-methoxybenzoate ester of dodecyl 4-hydroxybenzoate, and the benzoate ester of cyclohexylmethyl 4-hydroxybenzoate.

[0044] Furthermore, the component (iii) may be a compound represented by the following formula (10). [ka] (In the formula, R represents any one of an alkyl group having 3 to 18 carbon atoms, a cycloalkylalkyl group having 6 to 11 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, and an alkenyl group having 3 to 18 carbon atoms; X represents any one of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, and a halogen atom; and Y represents any one of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a methoxy group, an ethoxy group, and a halogen atom.) Examples of the compound represented by formula (10) include phenoxyethyl ether of nonyl 4-hydroxybenzoate, phenoxyethyl ether of decyl 4-hydroxybenzoate, phenoxyethyl ether of undecyl 4-hydroxybenzoate, and phenoxyethyl ether of dodecyl vanillate.

[0045] Furthermore, the component (iii) may be a compound represented by the following formula (11). [ka] (In the formula, R represents a cycloalkyl group having 3 to 8 carbon atoms or a cycloalkylalkyl group having 4 to 9 carbon atoms, and n represents an integer of 1 to 3.) Examples of the compound represented by formula (11) include a diester of 1,3-bis(2-hydroxyethoxy)benzene and cyclohexanecarboxylic acid, a diester of 1,4-bis(2-hydroxyethoxy)benzene and cyclohexanepropionic acid, and a diester of 1,3-bis(2-hydroxyethoxy)benzene and cyclohexanepropionic acid.

[0046] Furthermore, the component (iii) may be a compound represented by the following formula (12). [ka] (In the formula, R represents any one of an alkyl group having 3 to 17 carbon atoms, a cycloalkyl group having 3 to 8 carbon atoms, and a cycloalkylalkyl group having 5 to 8 carbon atoms; X represents any one of a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a methoxy group, an ethoxy group, and a halogen atom; and n represents an integer of 1 to 3.) Examples of the compound represented by formula (12) include a diester of 4-phenylphenol ethylene glycol ether and cyclohexane carboxylic acid, a diester of 4-phenylphenol diethylene glycol ether and lauric acid, a diester of 4-phenylphenol triethylene glycol ether and cyclohexane carboxylic acid, a diester of 4-phenylphenol ethylene glycol ether and octanoic acid, a diester of 4-phenylphenol ethylene glycol ether and nonanoic acid, a diester of 4-phenylphenol ethylene glycol ether and decanoic acid, and a diester of 4-phenylphenol ethylene glycol ether and myristic acid.

[0047] In addition, a reversible thermochromic composition of the heat-coloring type (which develops color when heated and loses color when cooled) using a gallic acid ester (JP Patent Publication No. 51-44706, JP Patent Publication No. 2003-253149) or the like as an electron-accepting compound, and a reversible thermochromic microcapsule pigment encapsulating the same can also be applied (see Figure 3).

[0048] The reversible thermochromic composition of the present invention is a compatible solution containing the above-mentioned components (A), (B), and (C) as essential components. The ratio of each component depends on the concentration, discoloration temperature, discoloration form, and type of each component, but the component ratio at which desired properties are generally obtained is in the range of 1 part by mass of component (A) to 0.1 to 100, preferably 0.1 to 50, and more preferably 0.5 to 20, of component (B), and 5 to 200, preferably 5 to 100, and more preferably 10 to 100, of component (C) (all the above ratios are in parts by mass).

[0049] Furthermore, the reversible thermochromic composition may contain various light stabilizers, if necessary. The light stabilizer is contained to prevent photodegradation of the reversible thermochromic composition consisting of the components (A), (B), and (C), and is blended in a ratio of 0.3 to 24% by mass, preferably 0.3 to 16% by mass, per 1% by mass of the component (A). Among the light stabilizers, the ultraviolet absorber effectively blocks ultraviolet rays contained in sunlight and the like, and prevents photodegradation caused by the excited state due to the photoreaction of the component (A). The antioxidant, singlet oxygen quencher, superoxide anion quencher, ozone quencher, etc. suppress oxidation reactions caused by light. The light stabilizers can be used alone or in a suitable mixture of two or more kinds.

[0050] The reversible thermochromic composition of the present invention is effective when used as is, but it can also be encapsulated in microcapsules to form a reversible thermochromic microencapsulated pigment (hereinafter sometimes referred to as a "microencapsulated pigment" or "pigment"), or dispersed in a thermoplastic resin or a thermosetting resin to form reversible thermochromic resin particles (hereinafter sometimes referred to as "resin particles"). The reversible thermochromic composition is preferably encapsulated in a microcapsule to form a reversible thermochromic microcapsule pigment, because the encapsulation in a microcapsule makes it possible to form a chemically and physically stable pigment, and the reversible thermochromic composition can be kept in the same composition under various conditions of use, and can exhibit the same effects. Microencapsulation may be carried out by any of the conventionally known methods, such as an isocyanate-based interfacial polymerization method, an in situ polymerization method such as a melamine-formaldehyde-based method, a liquid curing coating method, a phase separation method from an aqueous solution, a phase separation method from an organic solvent, a melting dispersion cooling method, an air suspension coating method, a spray drying method, etc., and may be appropriately selected depending on the application. Furthermore, a secondary resin film may be provided on the surface of the microcapsule depending on the purpose to impart durability or to modify the surface properties for practical use. The reversible thermochromic microcapsule pigment preferably has a mass ratio of inclusions to wall film of 7:1 to 1:1, and by having the mass ratio of inclusions to wall film within the above range, the decrease in color density and clarity during color development is prevented. More preferably, the mass ratio of inclusions to wall film is 6:1 to 1:1.

[0051] The average particle size of the reversible thermochromic microencapsulated pigment or resin particles is preferably 0.01 to 50 μm, more preferably 0.1 to 30 μm, and even more preferably 0.5 to 20 μm. If the average particle size of the microencapsulated pigment or resin particles exceeds 50 μm, the dispersion stability and processing suitability are lacking when blended into ink, paint, or resin. On the other hand, if the average particle size is less than 0.01 μm, it becomes difficult to exhibit high-concentration color development. Furthermore, when the microencapsulated pigment or resin particles are used in ink for writing instruments, the average particle size is preferably in the range of 0.01 to 5 μm, more preferably 0.05 to 4 μm, even more preferably 0.1 to 3 μm, and particularly preferably 0.5 to 3 μm. If the average particle size of the pigment or resin particles exceeds 5 μm, it becomes difficult to obtain good ink dischargeability when used in a writing instrument. On the other hand, if the average particle size is less than 0.01 μm, it becomes difficult to exhibit high-concentration color development. The average particle size was measured by determining the particle region using image analysis particle size distribution measurement software (manufactured by Mountec Corporation, product name: MacView), calculating the projected area equivalent circle diameter (Heywood diameter) from the area of ​​the particle region, and measuring the average particle size of particles equivalent to a sphere of equal volume using this value. In addition, when the particle size of all or the majority of the particles exceeds 0.2 μm, it is also possible to measure the average particle size of particles equivalent to an equal volume sphere by the Coulter method using a particle size distribution measuring device (product name: Multisizer 4e, manufactured by Beckman Coulter, Inc.). Furthermore, the volumetric particle size and average particle size may be measured using a calibrated laser diffraction / scattering particle size distribution analyzer (manufactured by HORIBA, Ltd., product name: LA-300) based on values ​​measured using the above software or a measuring device using the Coulter method.

[0052] A reversible thermochromic composition, a reversible thermochromic colorant such as a reversible thermochromic microcapsule pigment or resin particles is dispersed in a vehicle containing water and / or an organic solvent and, if necessary, various additives to form an ink composition (hereinafter, sometimes referred to as "ink"). It can be used as a reversible thermochromic liquid composition such as printing ink used in screen printing, offset printing, process printing, gravure printing, coater, pad printing, etc.; paint used in brush coating, spray coating, electrostatic coating, electrocoating, flow coating, roller coating, dip coating, etc.; inkjet ink; ultraviolet-curing ink; ink for writing instruments such as marking pens, ballpoint pens, fountain pens, and brush pens; ink for applicators; ink for stamps; paints; cosmetics; and coloring liquid for textiles.

[0053] The reversible thermochromic liquid composition may contain various additives. Examples of additives include resins, crosslinking agents, curing agents, drying agents, plasticizers, viscosity modifiers, dispersants, UV absorbers, antioxidants, light stabilizers, anti-settling agents, smoothing agents, gelling agents, defoamers, matting agents, penetrating agents, pH adjusters, foaming agents, coupling agents, moisturizing agents, antifungal agents, preservatives, and rust inhibitors.

[0054] Examples of the vehicle for use in the ink for a writing instrument include an oil-based vehicle containing an organic solvent, and an aqueous vehicle containing water and, if necessary, an organic solvent. Examples of organic solvents include ethanol, propanol, butanol, glycerin, sorbitol, triethanolamine, diethanolamine, monoethanolamine, ethylene glycol, diethylene glycol, thiodiethylene glycol, polyethylene glycol, propylene glycol, butylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, sulfolane, 2-pyrrolidone, and N-methyl-2-pyrrolidone.

[0055] A shear thinning agent can be blended into the ink for writing instruments. Ink containing a shear thinning agent (shear thinning ink) can suppress aggregation and sedimentation of the microencapsulated pigment and can also suppress bleeding of handwriting, thereby producing good handwriting. Furthermore, when a shear-thinning ink is contained in a ballpoint pen-shaped writing instrument, it is possible to prevent ink leakage from the gap between the ball and the tip when the writing instrument is not in use, and to prevent ink backflow when the writing tip is left facing upward (upright position).

[0056] Examples of shear thinning agents include xanthan gum, welan gum, succinoglycan (average molecular weight: about 1 to 8 million), which is an organic acid-modified heteropolysaccharide whose constituent monosaccharides are glucose and galactose, alka gum, guar gum, locust bean gum and its derivatives, hydroxyethyl cellulose, alginic acid alkyl esters, polymers having a molecular weight of 100,000 to 150,000 and mainly composed of alkyl esters of methacrylic acid, glucomannan, thickening polysaccharides having gelling ability extracted from seaweed such as agar and carrageenan, benzylidene sorbitol and benzylidene xylitol or derivatives thereof, cross-linked acrylic acid polymers, inorganic Examples of such surfactants include nonionic surfactants with an HLB value of 8 to 12, such as polyoxyethylene fine particles, polyglycerin fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyethylene glycol fatty acid esters, polyoxyethylene castor oil, polyoxyethylene lanolin / lanonin alcohol / beeswax derivatives, polyoxyethylene alkyl ethers / polyoxypropylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, and fatty acid amides, salts of dialkyl or dialkenyl sulfosuccinic acid, mixtures of N-alkyl-2-pyrrolidone and anionic surfactants, and mixtures of polyvinyl alcohol and acrylic resins.

[0057] Furthermore, a polymeric flocculant can be blended into the ink for writing instruments. In inks containing a polymeric flocculant (flocculant ink), the microencapsulated pigment forms loose aggregates via the polymeric flocculant, preventing the microencapsulated pigments from coming into contact with each other and agglomerating, thereby improving the dispersibility of the pigment.

[0058] Examples of the polymer flocculant include polyvinylpyrrolidone, polyethylene oxide, and water-soluble polysaccharides. Examples of water-soluble polysaccharides include tragacanth gum, guar gum, pullulan, cyclodextrin, water-soluble cellulose derivatives, and the like. Furthermore, examples of water-soluble cellulose derivatives include methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxyethyl methyl cellulose, and hydroxypropyl methyl cellulose. Among the above polymer flocculants, hydroxyethyl cellulose is preferred because of its excellent dispersibility.

[0059] Specific examples of polymer flocculants include those manufactured by Sumitomo Seika Chemicals Co., Ltd., product names: HEC A grade, S grade, and CF grade; those manufactured by Daicel-Phi-Chem Co., Ltd., product names: HEC Daicel SP type, SE type, and EE type; those manufactured by Dow Chemical Japan Co., Ltd., product names: CELLOSIZE WP type, QP type, and EP type; and those manufactured by Sansho Co., Ltd., product name: SANHEC. The polymer flocculant is preferably blended in an amount of 0.1 to 1 mass %, more preferably 0.3 to 0.5 mass %, based on the total amount of the ink. By being within the above range, the microencapsulated pigment forms gentle aggregates, and the effect of improving the dispersibility of the pigment can be fully exerted.

[0060] Furthermore, by blending a dispersant into the ink for writing instruments, the dispersibility of the microencapsulated pigment can be improved. In addition, a polymer flocculant and a dispersant can be used in combination. When the two are used in combination, the dispersibility of the microencapsulated pigment can be improved, and the dispersibility of the loose aggregates of the microencapsulated pigment formed via the polymer flocculant can be further improved.

[0061] Examples of dispersants include synthetic resins such as polyvinylpyrrolidone, polyvinyl butyral, polyvinyl ether, styrene-maleic acid copolymer, ketone resin, hydroxyethyl cellulose and its derivatives, styrene-acrylic acid copolymer, acrylic polymers, PO·EO adducts, and polyester amine oligomers. Among the above dispersants, acrylic polymer dispersants are preferred because they have excellent dispersibility for the microencapsulated pigment, acrylic polymer dispersants having a carboxyl group are more preferred, and acrylic polymer dispersants having a comb structure and a carboxyl group on the side chain are even more preferred. A particularly preferred dispersant is an acrylic polymer dispersant having a comb structure and multiple carboxyl groups in the side chains, and a specific example is Solsperse 43000 (product name: manufactured by Lubrizol Japan Co., Ltd.). The dispersant is preferably blended in an amount of 0.01 to 2% by mass, more preferably 0.1 to 1.5% by mass, based on the total amount of the ink. If the blending ratio of the dispersant exceeds 2% by mass, the microencapsulated pigment is likely to settle or float when subjected to external vibration, etc. On the other hand, if the blending ratio is less than 0.01% by mass, the effect of improving dispersibility is difficult to achieve.

[0062] Furthermore, by blending a water-soluble resin into the ink for writing instruments, it is possible to impart adhesion and viscosity to the handwriting on the paper surface. Examples of the water-soluble resin include alkyd resin, acrylic resin, styrene-maleic acid copolymer, cellulose derivatives, polyvinylpyrrolidone, polyvinyl alcohol, and dextrin. Among the above water-soluble resins, polyvinyl alcohol is preferred because it provides excellent stability to the acrylic polymer dispersant, and partially saponified polyvinyl alcohol with a degree of saponification of 70 to 89 mol % is more preferred because the ink is highly soluble even in the acidic range. The water-soluble resin is preferably blended in an amount of 0.3 to 3.0% by mass, more preferably 0.5 to 1.5% by mass, based on the total amount of the ink.

[0063] Furthermore, by blending a specific gravity adjuster into the ink for writing instruments, when the viscosity of the vehicle is low, it is possible to suppress the microencapsulated pigment from localizing due to settling or floating in the ink, thereby improving the dispersion stability of the microencapsulated pigment.

[0064] The dispersion stability of a pigment is at its highest when the difference in specific gravity between the vehicle and the pigment is minimal, and the specific gravity adjuster brings the specific gravity of the vehicle closer to that of the pigment. The specific gravity of the vehicle depends on the specific gravity of the water-soluble substance dissolved in the vehicle and the amount of the water-soluble substance added, so adding and dissolving a larger amount of a specific gravity adjuster with a larger specific gravity in the vehicle makes it possible to increase the specific gravity of the vehicle.

[0065] Examples of the specific gravity adjuster include oxyacids of Group 6 elements having an atomic weight of 90 to 185 and their salts. Such a specific gravity adjuster can adjust the specific gravity of the vehicle to be closer to that of the pigment, which has a higher specific gravity, and can suppress localized settling or floating of the pigment due to the application of external stimuli such as vibration, even while the ink has a low viscosity.

[0066] The oxygen acid and its salt are selected from the group consisting of oxygen acids of transition metal elements and their salts, and the oxygen acid ion is said to form a tetrahedron or octahedron in which oxygen atoms are usually coordinated 4- or 6-fold to the metal atom, etc. The tetrahedral or octahedral units may be a single unit, or may be a polyacid having a structure in which the tetrahedral or octahedral units are bonded via edges or vertices, and may be a polyacid salt, which is a salt thereof. A polyacid is a polyacid formed by condensation of oxyacids of metal elements, but a polyacid composed of only one type of metal and in which all the condensed anions are of the same type is called an isopolyacid, and a polyacid in which two or more types of anions are condensed is called a heteropolyacid. The respective salts are called isopolyacid salts and heteropolyacid salts. The above polyacids include isopolyacids, heteropolyacids, etc., and the above polyacid salts include isopolyacids, heteropolyacids, etc.

[0067] The specific gravity adjuster may, for example, be a single oxyacid and its salt, an isopolyacid and its salt, or a heteropolyacid and its salt. Examples of the single oxyacid include molybdic acid and tungstic acid, and examples of the salt of the single oxyacid include sodium molybdate, potassium molybdate, ammonium molybdate, sodium tungstate, potassium tungstate, ammonium tungstate, lithium tungstate, and magnesium tungstate. Examples of isopolyacids include metamolybdic acid, paramolybdic acid, metatungstic acid, paratungstic acid, isotungstic acid, and the like. Further, examples of isopolyacid salts include sodium metamolybdate, potassium metamolybdate, ammonium metamolybdate, sodium paramolybdate, potassium paramolybdate, ammonium paramolybdate, sodium metatungstate, potassium metatungstate, ammonium metatungstate, barium metatungstate, sodium paratungstate, sodium isotungstate, and the like. Examples of heteropolyacids include molybdophosphoric acid, molybdosilicic acid, tungstophosphoric acid, and tungstosilicic acid, and examples of heteropolyacid salts include sodium molybdophosphate, sodium molybdosilicate, sodium tungstophosphate, and sodium tungstosilicate. The above oxygen acids and salts thereof may be used alone or in a suitable mixture of two or more kinds.

[0068] Among the above-mentioned specific gravity adjusters, metatungstic acid, paratungstic acid, sodium metatungstate, potassium metatungstate, ammonium metatungstate, barium metatungstate, sodium paratungstate, sodium isotungstate, tungstophosphoric acid, tungstosilicic acid, sodium tungstophosphate, and sodium tungstosilicate are preferred, and sodium isotungstate, sodium metatungstate, and sodium paratungstate are more preferred. The above-mentioned sodium isotungstate, sodium metatungstate, and sodium paratungstate are not only highly safe but also have a high specific gravity themselves, so that it is easy to adjust the high specific gravity liquid according to the amount added, and therefore they are preferably used.

[0069] The specific gravity adjuster is preferably blended in an amount of 2 to 20% by mass, more preferably 5 to 15% by mass, based on the total amount of the ink. If the blending ratio of the specific gravity adjuster exceeds 20% by mass, the microcapsule pigment tends to aggregate. On the other hand, if the blending ratio is less than 2% by mass, the specific gravity adjustment effect of the vehicle becomes poor. The mass ratio of the microencapsulated pigment to the specific gravity adjusting agent is preferably 1:0.05-4.0, more preferably 1:0.075-2.0, and even more preferably 1:0.1-1.5.

[0070] The vehicle containing the above-mentioned specific gravity adjuster is particularly effective for pigments with high specific gravity, and while the ink has a low viscosity, it is possible to suppress the pigment from settling in the ink when subjected to external stimuli such as vibration, thereby improving the dispersion stability of the pigment. The specific gravity of the microencapsulated pigment depends on the particle size of the microencapsulated pigment, the components and their contents contained in the microcapsules, the components and film thickness of the capsule wall membrane, the colored state of the microencapsulated pigment, and the temperature, but the specific gravity is preferably 1.05 to 1.20 when the microencapsulated pigment is in a completely colored state and water is used as a reference at 20°C. Such pigments exhibit a large hysteresis width (ΔH), and can be decolorized by heating and can maintain the decolorized state in a specific temperature range. However, pigments with a large hysteresis width (ΔH) often use a compound having two or more aromatic rings in the molecule as the component (c), so that the specific gravity is likely to be large and the pigments tend to settle and separate in the ink, and in particular, the pigments tend to settle and separate when an external stimulus such as vibration is applied. However, in inks containing the above-mentioned specific gravity adjusters, the ink has a low viscosity, but the microencapsulated pigment is prevented from settling and localizing, and the dispersion stability of the pigment is improved, so that the specific gravity adjusters are preferably used. Considering the dispersion stability of the pigment in the ink, the specific gravity of the pigment when the microencapsulated pigment is in a completely colored state is preferably 1.10 to 1.20, and more preferably 1.12 to 1.15, based on water at 20°C. The specific gravity of the microcapsulated pigment can be measured by the following method.

[0071] (Method for measuring specific gravity of microcapsule pigment) 1. 30 ml of glycerin aqueous solution and 1 g of fully colored microcapsule pigment are added to a screw cap bottle and mixed to obtain a microcapsule pigment dispersion. 2. 30 ml of the microcapsule pigment dispersion is adjusted to 20° C. and centrifuged at 1000 rpm for 30 seconds. A refrigerated tabletop centrifuge (manufactured by Kokusan Co., Ltd., product name: H103N) can be used as the centrifuge. 3. Observe the microcapsule pigment dispersion. If most of the microencapsulated pigment has settled to the bottom of the beaker, repeat steps 1 and 2 using an aqueous solution with a higher glycerin concentration than that used at this time, and observe the state of the dispersion. If it is confirmed that most of the microencapsulated pigment is floating on the liquid surface, repeat steps 1 and 2 using an aqueous solution with a lower glycerin concentration than the glycerin aqueous solution used earlier, and observe the state of the dispersion. The above series of operations is repeated until it is visually confirmed that the majority of the microencapsulated pigment is not floating on the surface or settling, but that the glycerin aqueous solution is uniformly colored except for the surface of the glycerin aqueous solution and the area near the bottom of the screw tube bottle. The specific gravity of the glycerin aqueous solution when this state is observed is measured and used as the specific gravity of the microencapsulated pigment. The specific gravity of the glycerin aqueous solution can be measured by the hydrometer method described in JIS K0061, Section 7.1, using an aqueous solution adjusted to 20°C.

[0072] Furthermore, the vehicle containing the specific gravity adjuster has a specific gravity in the range of 1.00 to 1.30 at 20° C. when water is used as the reference substance, and the specific gravity is preferably 1.05 to 1.20, and more preferably 1.08 to 1.18. Furthermore, the specific gravity of the vehicle is preferably 0.90 to 1.20 times, and more preferably 0.95 to 1.10 times, the specific gravity of the pigment. When the specific gravity of the vehicle is within the above range and the specific gravity of the vehicle relative to the specific gravity of the pigment is also within the above range, when the ink is subjected to an external stimulus such as vibration, the pigment can be further prevented from settling and localizing in the ink, even though the ink has a low viscosity, thereby further improving the dispersion stability of the pigment.

[0073] When the vehicle for the writing instrument is an aqueous vehicle, the vehicle contains at least water, and the water is preferably blended in an amount of 30 to 80% by mass, more preferably 40 to 70% by mass, based on the total amount of the ink.

[0074] Furthermore, by blending a water-soluble organic solvent into the ink for writing instruments, evaporation of water from the ink can be suppressed, fluctuations in the specific gravity of the vehicle can be prevented, and good dispersion stability of the microencapsulated pigment can be maintained, while the structure of the polymer flocculant or the loose aggregates formed by the polymer flocculant and the dispersant can be stabilized. Examples of the water-soluble organic solvent include ethanol, propanol, butanol, glycerin, sorbitol, triethanolamine, diethanolamine, monoethanolamine, ethylene glycol, diethylene glycol, thioethylene glycol, polyethylene glycol, propylene glycol, butylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, sulfolane, 2-pyrrolidone, and N-methyl-2-pyrrolidone. When the hysteresis width (ΔH) of the microencapsulated pigment to be incorporated into the ink is large, the specific gravity of the microencapsulated pigment is greater than 1. Since using a water-soluble organic solvent with a specific gravity greater than that of water makes it easier to adjust the specific gravity when adjusting the specific gravity of the vehicle, it is preferable to use glycerin or the like with a specific gravity of more than 1.1 as the water-soluble organic solvent.

[0075] The water-soluble organic solvent is preferably blended in an amount of 1 to 40% by mass, more preferably 5 to 30% by mass, and even more preferably 10 to 25% by mass, based on the total amount of the ink. If the blending ratio of the water-soluble organic solvent exceeds 40% by mass, the ink viscosity tends to increase. On the other hand, if the blending ratio is less than 1% by mass, the effect of suppressing water evaporation becomes poor.

[0076] Furthermore, when the writing instrument ink is used in a ballpoint pen, it is preferable to add a lubricant such as a higher fatty acid such as oleic acid, a nonionic surfactant having a long-chain alkyl group, a polyether-modified silicone oil, a thiophosphite triester such as thiophosphite tri(alkoxycarbonylmethyl ester) and thiophosphite tri(alkoxycarbonylethyl ester), a polyoxyethylene alkyl ether or polyoxyethylene alkylaryl ether phosphate monoester, a polyoxyethylene alkyl ether or polyoxyethylene alkylaryl ether phosphate diester, or a metal salt, ammonium salt, amine salt or alkanolamine salt thereof to the ink in order to prevent wear of the ball seat.

[0077] Other examples of the additives that may be used as necessary include extenders such as kaolin, talc, mica, clay, bentonite, calcium carbonate, aluminum hydroxide, sericite, and potassium titanate, wetting agents such as fluorine-based surfactants and nonionic surfactants, acrylic resins, urethane resins, styrene-butadiene resins, alkyd resins, sulfamide resins, maleic acid resins, polyvinyl acetate, ethylene-vinyl acetate copolymers, vinyl chloride-vinyl acetate copolymers, styrene-maleic acid ester copolymers, styrene-acrylonitrile copolymers, cyanate-modified polyalkylene glycols, ester gums, xylene resins, urea resins, urea aldehyde resins, phenolic resins, alkylphenolic resins, terpene phenolic resins, rosin-based resins and their hydrogenated compounds, rosin phenolic resins, polyvinyl alkyl ethers, polyamides, polyolefins, nylon resins, polyesters, and cyclohexafluorophenyl ethers. It is also possible to compound additives such as water-soluble resins used as fixing agents, such as non-based resins, emulsions made of water-insoluble resins, resin particles made of polyolefins, acrylic resins, nylon resins, silicone resins, urethane resins, fluororesins, etc., pH adjusters such as inorganic salts, such as ammonia, sodium carbonate, sodium phosphate, sodium hydroxide, sodium acetate, and organic basic compounds, such as water-soluble amine compounds, rust inhibitors, such as benzotriazole, tolyltriazole, dicyclohexylammonium nitrite, diisopropylammonium nitrite, and saponin, wetting agents, such as urea, nonionic surfactants, reduced or non-reduced starch hydrolysates, disaccharides, such as trehalose, oligosaccharides, sucrose, cyclodextrin, glucose, dextrin, sorbitol, mannitol, and sodium pyrophosphate, antifoaming agents, viscosity adjusters, preservatives, and fungicides.

[0078] The reversible thermochromic microencapsulated pigment is preferably blended in the above-mentioned writing ink in an amount of 5 to 40% by mass, more preferably 10 to 40% by mass, and even more preferably 10 to 30% by mass, based on the total amount of the ink. By blending the microencapsulated pigment in the above-mentioned range, the desired color density can be obtained and a decrease in ink outflow can be prevented.

[0079] The ink composition according to the present invention can be produced by any conventionally known method. Specifically, the ink composition can be produced by blending the above-mentioned components in required amounts and mixing them with various stirrers such as a propeller stirrer, a homodisper, or a homomixer, or various dispersing machines such as a bead mill.

[0080] When the ink for a writing instrument according to the present invention is used in a ballpoint pen, its viscosity is 100 g / ml at a rotation speed of 1 rpm (shear rate of 3.84 sec) in an environment of 20° C. -1 When the viscosity is measured under the conditions of 100 rpm (shear rate 384 sec), the viscosity is preferably 1 to 2000 mPa·s, more preferably 3 to 1500 mPa·s, and even more preferably 500 to 1000 mPa·s, because this can suppress the settling or aggregation of the microencapsulated pigment. -1 ), the viscosity is preferably 1 to 200 mPa s, more preferably 10 to 100 mPa s, and even more preferably 20 to 50 mPa s, because this allows for good ink discharge from the pen tip of the ballpoint pen. By having the viscosity within the above range, the dispersion stability of the microencapsulated pigment and the free flowability of the ink within the mechanism of the ballpoint pen can be maintained at a high level. The viscosity was measured using a rheometer (TA Instruments, product name: Discovery HR-2, cone plate (diameter 40 mm, angle 1°)) at a rotation speed of 1 rpm (shear rate 3.84 sec) with the ink placed in an environment of 20°C. -1 ), or rotation speed 100 rpm (shear rate 384 sec -1 ) values ​​measured under the conditions.

[0081] When the writing ink according to the present invention is used in a ballpoint pen, the surface tension is preferably 20 to 50 mN / m, and more preferably 25 to 45 mN / m, in an environment of 20° C. By having a surface tension within the above range, bleeding of written lines and strike-through onto the paper surface can be easily suppressed, and the wettability of the ink to the paper surface can be improved. The surface tension was measured using a surface tension meter (manufactured by Kyowa Interface Science Co., Ltd., product name: DY-300) by placing the ink in an environment of 20°C using a vertical plate method using a platinum plate.

[0082] When the writing ink according to the present invention is used in a ballpoint pen, its pH is preferably from 3 to 10, and more preferably from 4 to 9. By having the pH within the above range, aggregation or precipitation of the microencapsulated pigment contained in the ink in the low temperature range can be suppressed. The pH value was measured by placing the ink in an environment of 20° C. using a pH meter (manufactured by DKK-TOA Corporation, product name: IM-40S).

[0083] When the writing instrument ink according to the present invention is used in a marking pen, the viscosity thereof is preferably 1 to 20 mPa·s, more preferably 1 to 10 mPa·s, and even more preferably 1 to 5 mPa·s, when measured at a rotation speed of 30 rpm in an environment of 20° C. Having a viscosity within the above range can improve the fluidity of the ink and the dispersion stability of the microencapsulated pigment. The viscosity was measured by placing the ink in an environment of 20°C using a BL type rotational viscometer (manufactured by Toki Sangyo Co., Ltd., product name: TVB-M type viscometer, L type rotor).

[0084] When the writing ink according to the present invention is used in a marking pen, the surface tension is preferably 25 to 50 mN / m, more preferably 25 to 45 mN, and even more preferably 35 to 45 mN / m in an environment of 20° C. By having a surface tension within the above range, bleeding of written lines and strike-through onto the paper surface can be easily suppressed, and the wettability of the ink to the paper surface can be improved. The surface tension was measured using a surface tension meter (manufactured by Kyowa Interface Science Co., Ltd., product name: DY-300) by placing the ink in an environment of 20° C. and using a vertical plate method with a glass plate.

[0085] When the writing ink according to the present invention is used in a marking pen, its pH is preferably from 3 to 8, more preferably from 4 to 7, and even more preferably from 5 to 6. By having the pH within the above range, aggregation or precipitation of the microencapsulated pigment contained in the ink in the low temperature range can be suppressed. The pH value was measured by placing the ink in an environment of 20° C. using a pH meter (manufactured by DKK-TOA Corporation, product name: IM-40S).

[0086] The above-mentioned writing instrument ink is contained in a writing instrument which includes a pen tip, an ink filling mechanism, and an ink supply mechanism for supplying the ink filled in the ink filling mechanism to the pen tip. Examples of writing implements include ballpoint pens, marking pens, fountain pens, brush pens, calligraphy pens, and other various writing implements.

[0087] The pen tip of the writing implement is not particularly limited, and pen tips equipped with various types of tips can be used. Among various types of tips, examples of ballpoint pen tips include tips in which a ball is held in a ball-holding portion formed by deforming the vicinity of the tip of a metal pipe by pressing inward from the outer surface, tips in which a ball is held in a ball-holding portion formed by cutting a metal material with a drill or the like, tips in which a resin ball receiving seat is provided inside a metal or plastic tip, and tips in which the ball held in the tip is urged forward by a spring body. The material of the ballpoint pen tip and ball is not particularly limited, and examples thereof include cemented carbide (super hard), stainless steel, ruby, ceramic, resin, rubber, and the like. The diameter of the ball is preferably 0.1 to 3.0 mm, more preferably 0.2 to 2.0 mm, and even more preferably 0.3 to 1.0 mm. The ball may be subjected to a surface treatment such as a DLC coating.

[0088] Examples of marking pen tips include conventional porous members with interconnected pores, such as resin-processed fibers, fused heat-fusible fibers, and felt, which have a porosity selected from a range of approximately 30 to 70%, or extrusion-molded synthetic resin bodies with multiple ink outlet holes extending in the axial direction, one end of which can be processed into a bullet shape, rectangular shape, chisel shape, or other shape suited to the purpose for which it is used.

[0089] Examples of the tip (pen body) of a fountain pen include a metal plate such as a stainless steel plate or a gold alloy plate cut into a tapered shape and then bent or curved, or a resin molded into a pen tip shape. The pen body may have a slit in the center or a ball at the tip.

[0090] When filling a ballpoint pen with ink for a writing instrument, the structure and shape of the ballpoint pen itself are not particularly limited, and an example is a ballpoint pen having an ink reservoir tube filled with shear-thinning ink inside a barrel, the ink reservoir tube communicating with a ballpoint pen tip having a ball attached to the tip, and further having a liquid plug in close contact with the end face of the ink to prevent backflow.

[0091] The ink filling mechanism is disposed behind the ink supply mechanism and may be configured to directly fill the ink composition, or may be equipped with an ink container or ink occlusion body into which the ink composition can be filled. When the writing instrument is configured to be filled directly with the ink for the writing instrument, it is preferable that the ink container has a stirring body such as a stirring ball for stirring the ink built in to facilitate redispersion of the pigment. Examples of the shape of the stirring body include a spherical body, a rod-shaped body, etc. The material of the stirring body is not particularly limited, and examples thereof include metal, ceramic, resin, glass, etc.

[0092] The ink reservoir may be, for example, a molded body made of a thermoplastic resin such as polyethylene, polypropylene, polyethylene terephthalate, or nylon, or a tubular body made of metal. The ink reservoir may be connected to the tip directly or through a connecting member. In addition, the ink container may be in the form of a refill, with the refill housed in a barrel made of resin, metal, etc., or the barrel itself with a tip attached to the tip may serve as the ink container, with ink being filled directly into the barrel.

[0093] The rear end of the ink filled in the ink reservoir is filled with an ink backflow preventive composition. The ink backflow preventer composition comprises a non-volatile liquid and / or a hardly volatile liquid, examples of which include petrolatum, spindle oil, castor oil, olive oil, refined mineral oil, liquid paraffin, polybutene, α-olefin, α-olefin oligomer or cooligomer, dimethyl silicone oil, methylphenyl silicone oil, amino-modified silicone oil, polyether-modified silicone oil, and fatty acid-modified silicone oil. The ink backflow preventive composition may be used alone or in a suitable mixture of two or more kinds.

[0094] It is preferable to add a thickener to the ink backflow preventer composition to thicken it to a suitable viscosity. Examples of thickeners include silica whose surface has been hydrophobically treated, fine particle silica whose surface has been methylated, aluminum silicate, swellable mica, clay-based thickeners such as hydrophobically treated bentonite and montmorillonite, fatty acid metal soaps such as magnesium stearate, calcium stearate, aluminum stearate, and zinc stearate, dextrin-based compounds such as tribenzylidene sorbitol, fatty acid amides, amide-modified polyethylene wax, hydrogenated castor oil, fatty acid dextrins, and cellulose-based compounds. Furthermore, the above-mentioned liquid ink backflow preventive composition and a solid ink backflow preventive composition can be used in combination.

[0095] In addition, when the writing instrument is equipped with an ink occlusion body that can be filled with writing instrument ink, the ink occlusion body is a fiber bundle in which crimped fibers are bundled in the longitudinal direction, and is contained within a covering body such as a plastic cylinder or film, and is configured with a porosity adjusted to a range of approximately 40 to 90%.

[0096] Furthermore, the ink refilling mechanism can be in the form of an ink cartridge, which is a removable structure. In this case, the writing instrument body is used after the ink contained therein is used up and replaced with a new cartridge, so it is necessary to make the ink in the ink reservoir of the ink refilling mechanism flow smoothly to the pen tip. As the ink cartridge, one that doubles as the barrel that constitutes the writing instrument when connected to the main body of the writing instrument, or one that covers and protects the barrel (rear barrel) after being connected to the main body of the writing instrument, is used. In addition to being used as a single ink cartridge, the latter may be one in which the main body of the writing instrument and the ink cartridge are connected in the writing instrument before use, or one that is stored in the barrel in a disconnected state so that the user of the writing instrument can connect the ink cartridge in the barrel when using the writing instrument and start using it.

[0097] The ink supply mechanism is not particularly limited, but examples include: (1) a mechanism that has an ink guide core made of a fiber bundle or the like as an ink flow regulator and supplies ink to the pen tip; (2) a mechanism that has a comb-shaped ink flow regulator and supplies ink to the pen tip through this; (3) a mechanism that supplies ink to the pen tip via a pen core consisting of a number of disks arranged in parallel with comb-shaped intervals, with slit-shaped ink guide grooves running vertically through the disks in the axial direction and wide ventilation grooves formed beyond the grooves, and with an ink guide core arranged in the axial center to guide ink from the ink filling mechanism to the pen tip; (4) a mechanism that has an ink flow regulator with a valve mechanism and supplies ink to the pen tip; and (5) a mechanism that supplies ink directly to the pen tip from an ink container or barrel equipped with a pen tip. The material of the pen core is not particularly limited as long as it is a synthetic resin that can be injection molded into a structure in which multiple disks are arranged in a comb groove shape. Examples of synthetic resins include general-purpose polycarbonate, polypropylene, polyethylene, and acrylonitrile-butadiene-styrene copolymer (ABS resin). In particular, acrylonitrile-butadiene-styrene copolymer (ABS resin) is preferably used because it has high moldability and is easy to obtain pen core performance. The valve mechanism may be of a conventional, general-purpose pumping type, but is preferably set to a spring pressure that can be opened by the pressure of the writing pen. Examples of ink containers equipped with a pen tip include ballpoint pen refills in which the ink container is filled with ink, a ballpoint pen tip is attached to one end of the ink container, and an ink backflow prevention body is further filled from the other end; and ballpoint pen refills or marking pen refills in which an ink occlusion body impregnated with ink is contained within the ink container, and a ballpoint pen tip or marking pen tip is attached to one end of the ink container.

[0098] Furthermore, it is preferable that writing instruments such as ballpoint pens or marking pens be provided with a cap that is attached so as to cover the writing tip (tip tip) or with a retractable mechanism that allows the writing tip to protrude and retract from the writing instrument body (barrel), thereby preventing the writing tip from drying out and becoming unable to write, and preventing the writing tip from becoming contaminated or damaged. A writing instrument with a retractable mechanism is stored within a barrel with the writing tip exposed to the outside air, and any structure in which the writing tip protrudes from the opening of the barrel when the retractable mechanism is activated can be used. For example, a writing instrument with a retractable mechanism (a retractable writing instrument) can be made by producing the ballpoint pen refill or marking pen refill described above, storing the refill within the barrel, and configuring it so that the writing tip protrudes from the opening of the barrel when the retractable mechanism is activated. Furthermore, when a ballpoint pen-shaped writing instrument is provided with a retractable mechanism, it can also be a composite type retractable writing instrument (retractable ballpoint pen) that contains multiple ballpoint pen refills within the barrel and causes the writing tip of one of the ballpoint pen refills to appear and retract from the opening of the barrel by activation of the retractable mechanism.

[0099] Examples of the retraction mechanism include: (1) a side-slide type retraction mechanism in which an operating part (clip) that can move in the front-rear direction protrudes radially outward from the rear side wall of the barrel, and the operating part is slid forward to cause the writing tip to appear and disappear from the front opening of the barrel; (2) a rear-end knock type retraction mechanism in which an operating part provided at the rear end of the barrel is pressed forward to cause the writing tip to appear and disappear from the front opening of the barrel; (3) a side-knock type retraction mechanism in which an operating part protruding from the outer surface of the side wall of the barrel is pressed radially inward to cause the writing tip to appear and disappear from the front opening of the barrel; and (4) a rotating type retraction mechanism in which an operating part at the rear of the barrel is rotated to cause the writing tip to appear and disappear from the front opening of the barrel.

[0100] Furthermore, the shape of the ballpoint pen or marking pen is not limited to the configuration described above, and it may be equipped with tips of different shapes, or with pen tips that dispense ink of different colors, or it may be a composite writing instrument (double-headed, retractable tip, etc.) that is equipped with tips of different shapes and dispenses ink of different colors from each tip.

[0101] The handwriting obtained by writing on a surface to be written on using a writing instrument containing the above-mentioned ink for writing instruments can be discolored by rubbing with a finger or by using a heating or cooling tool. Examples of the heating device include an electrically-heated discoloring device equipped with a resistive heating element such as a PTC element, a heat discoloring device filled with a medium such as hot water, a heat discoloring device using steam or laser light, and the application of a hair dryer. However, friction members and friction bodies are preferred because they can change color in a simple manner. Examples of cooling devices include electrochemically-induced color-changing devices using a Peltier element, color-changing devices filled with a refrigerant such as cold water or ice chips, cooling agents, refrigerators, freezers, and the like.

[0102] As the friction member and friction body, an elastic body such as an elastomer or a plastic foam, which has a high elastic feel and can generate appropriate friction and generate frictional heat when rubbed, is preferable, but a plastic molded body, stone, wood, metal, cloth, etc. can also be used. Although a general eraser used for erasing pencil marks may be used to rub the marks, the rubbed marks will generate eraser dust. Therefore, the above-mentioned friction member and friction body which generate almost no eraser dust are preferably used. Examples of the material of the friction member and the friction body include silicone resin, SEBS resin (styrene-ethylene-butadiene-styrene block copolymer), etc. Silicone resin is likely to adhere to the part erased by rubbing, and handwriting tends to be repelled when writing is repeated, so SEBS resin is more preferably used.

[0103] The friction member or friction body may be a member of any shape that is separate from the writing instrument, but by providing it on the writing instrument, the writing instrument can be made highly portable. Also, a writing instrument set can be obtained by combining a writing instrument with a friction member or friction body of any shape that is separate from the writing instrument.

[0104] In the case of a writing instrument with a cap, the location where the friction member or friction body is provided is not particularly limited. For example, the cap itself may be formed from a friction member, the barrel itself may be formed from a friction member, and in the case where a clip is provided, the clip itself may be formed from a friction member, or the friction member or friction body may be provided at the tip (top) of the cap or the rear end of the barrel (the part where the writing tip is not provided), etc. When the writing instrument is a retractable writing instrument, the location where the friction member or friction body is provided is not particularly limited. For example, the barrel itself may be formed from a friction member, and if a clip is further provided, the clip itself may be formed from a friction member, or the friction member or friction body may be provided near the opening of the barrel, at the rear end of the barrel (the portion where the writing tip is not provided), or at the knock portion.

[0105] The ink can also be used as a stamp ink. Water is used as the medium for the ink for stamping, but a water-soluble organic solvent can also be used if necessary. Examples of the water-soluble organic solvent include glycols such as glycerin, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, 1,3-butylene glycol, and ethylene glycol monomethyl ether, as well as lower alkyl ethers thereof, 2-pyrrolidone, N-vinylpyrrolidone, and urea. When a reversible thermochromic microencapsulated pigment is used in the ink for stamps, glycerin or propylene glycol is preferred among the above water-soluble organic solvents.

[0106] The water-soluble organic solvent is preferably blended in an amount of 30 to 60% by mass, more preferably 30 to 55% by mass, and even more preferably 40 to 50% by mass, based on the total amount of the ink. By blending the water-soluble organic solvent in the above range, the ink does not dry out or absorb moisture, making it easier to obtain a clear printed image. If the blending ratio of the water-soluble organic solvent exceeds 60% by mass, the moisture absorption is likely to be high, and the printed image may bleed or become mottled, making it difficult to obtain a clear printed image. On the other hand, if the blending ratio is less than 30% by mass, the printed surface may dry out, causing the printed image to fade, making it difficult to obtain a clear printed image.

[0107] As the medium, in addition to the water-soluble organic solvent, an organic solvent can also be used. Examples of the organic solvent include castor oil fatty acid alkyl esters, cellosolve-based solvents such as methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, and ethyl cellosolve acetate, ethylene glycol acetate, ethylene glycol diethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol dimethyl ether, diethylene glycol monoethyl ether acetate, propylene glycol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol monomethyl ether acetate, and tripropylene glycol monomethyl ether. alkylene glycol solvents such as ethyl ether, ethyl formate, amyl formate, ethyl acetate, ethyl acetoacetate, propyl acetate, butyl acetate, 3-methyl-3-methoxybutyl acetate, amyl acetate, methyl-3-methoxypropionate, ethyl-3-methoxypropionate, ethyl-3-ethoxypropionate, propyl-3-methoxypropionate, butyl-3-methoxypropionate, methyl lactate, ethyl lactate, ethyl-2-hydroxybutyrate, butyl butyrate, butyl stearyl alcohol, etc. Ester-based solvents such as ethyl arylene, ethyl caprate, diethyl oxalate, ethyl pyruvate, and ethyl benzoate; hydrocarbon-based solvents such as n-pentane, n-hexane, n-octane, n-dodecane, diisobutylene, dipentene, hexene, methylcyclohexene, bicyclohexyl, and mineral spirits; halogenated hydrocarbon-based solvents such as amyl chloride and butyl chloride; alcohol-based solvents such as 3-methoxy-3-methylbutanol and 3-methoxy-3-methylpentanol; diethyl ether, dipropyl ether,Examples of the solvent include ether solvents such as ethyl isobutyl ether, dibutyl ether, diisopropyl ether, diamyl ether, and dihexyl ether; ketone solvents such as acetone, methyl ethyl ketone, methyl isopropyl ketone, methyl butyl ketone, methyl isobutyl ketone, methyl isoamyl ketone, ethyl amyl ketone, methyl hexyl ketone, methyl nonyl ketone, diisopropyl ketone, diisobutyl ketone, methoxymethyl pentanone, and cyclohexanone; propionic acid solvents such as 3-methoxypropionic acid and 3-ethoxypropionic acid; highly polar solvents such as dimethylformamide, dimethylacetamide, dimethylsulfoxide, N-methylpyrrolidone, and benzonitrile; and mixed solvents thereof.

[0108] Furthermore, a thickener can be added to the ink for stamping. Examples of thickening agents include xanthan gum, welan gum, succinoglycan (average molecular weight: about 1 to 8 million), which is an organic acid-modified heteropolysaccharide whose constituent monosaccharides are glucose and galactose, guar gum, locust bean gum and its derivatives, hydroxyethyl cellulose, alginic acid alkyl esters, polymers having a molecular weight of 100,000 to 150,000 and mainly composed of alkyl esters of methacrylic acid, glycomannan, thickening polysaccharides having gelling ability extracted from seaweed such as agar and carrageenin, benzylidene sorbitol and benzylidene xylitol, or the like. Examples of such surfactants include derivatives of these, crosslinkable acrylic acid polymers, inorganic fine particles, polyglycerin fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyethylene glycol fatty acid esters, polyoxyethylene castor oil, polyoxyethylene lanolin / lanolin alcohol / beeswax derivatives, polyoxyethylene alkyl ethers / polyoxypropylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, fatty acid amides and other nonionic surfactants having an HLB value of 8 to 12, and salts of dialkyl or dialkenyl sulfosuccinic acid. Among the above thickeners, alkali-soluble acrylic emulsions are preferred. When an alkali-soluble acrylic emulsion is used as the thickener, the pH of the ink is preferably 6-11, more preferably 7-11, and even more preferably 7-10.

[0109] Furthermore, by adding a binder resin to the ink for stamping, the adhesion of the printed image can be improved and the viscosity of the ink can be adjusted. Examples of the binder resin include a resin emulsion, an alkali-soluble resin, and a water-soluble resin. Examples of resin emulsions include aqueous dispersions of polyacrylic acid esters, styrene-acrylic acid copolymers, polyvinyl acetate, ethylene-vinyl acetate copolymers, ethylene-vinyl chloride copolymers, methacrylic acid-maleic acid copolymers, ethylene-methacrylic acid copolymers, α-olefin-maleic acid copolymers, polyesters, polyurethanes, and the like. Examples of the alkali-soluble resin include styrene-maleic acid copolymer, ethylene-maleic acid copolymer, and styrene-acrylic acid copolymer. Examples of the water-soluble resin include polyvinyl alcohol and polyvinyl butyral. The above resin emulsions can be used alone or in a suitable mixture of two or more kinds.

[0110] Other examples of the additives that may be used as necessary include extenders such as kaolin, talc, mica, clay, bentonite, calcium carbonate, aluminum hydroxide, sericite, and potassium titanate, wetting agents such as fluorine-based surfactants and nonionic surfactants, acrylic resins, urethane resins, styrene-butadiene resins, alkyd resins, sulfamide resins, maleic acid resins, polyvinyl acetate, ethylene-vinyl acetate copolymers, vinyl chloride-vinyl acetate copolymers, styrene-maleic acid ester copolymers, styrene-acrylonitrile copolymers, cyanate-modified polyalkylene glycols, ester gums, xylene resins, urea resins, urea aldehyde resins, phenolic resins, alkylphenolic resins, terpene phenolic resins, rosin-based resins and their hydrogenated compounds, rosin phenolic resins, polyvinyl alkyl ethers, polyamides, polyolefins, nylon resins, polyesters, and cyclohexafluorophenyl ethers. It is also possible to compound additives such as water-soluble resins used as fixing agents, such as non-based resins, emulsions made of water-insoluble resins, resin particles made of polyolefins, acrylic resins, nylon resins, silicone resins, urethane resins, fluororesins, etc., pH adjusters such as inorganic salts, such as ammonia, sodium carbonate, sodium phosphate, sodium hydroxide, sodium acetate, and organic basic compounds, such as water-soluble amine compounds, rust inhibitors, such as benzotriazole, tolyltriazole, dicyclohexylammonium nitrite, diisopropylammonium nitrite, and saponin, wetting agents, such as urea, nonionic surfactants, reduced or non-reduced starch hydrolysates, disaccharides, such as trehalose, oligosaccharides, sucrose, cyclodextrin, glucose, dextrin, sorbitol, mannitol, and sodium pyrophosphate, antifoaming agents, viscosity adjusters, preservatives, and fungicides. Furthermore, if necessary, resins such as acrylic resins, styrene-maleic acid copolymers, cellulose derivatives, polyvinylpyrrolidone, polyvinyl alcohol, and dextrin can be added to impart adhesion and viscosity to the paper surface.

[0111] The reversible thermochromic microencapsulated pigment is preferably blended in the stamp ink in an amount of 10 to 40% by mass, more preferably 10 to 35% by mass, and even more preferably 10 to 30% by mass, based on the total amount of the ink. If the blending ratio of the microencapsulated pigment exceeds 40% by mass, the dispersion stability of the microencapsulated pigment in the ink tends to decrease. On the other hand, if the blending ratio is less than 10% by mass, the color density tends to decrease.

[0112] The above-mentioned ink for stamps can be used as ink for stamp pads and ink for stamps equipped with a printing material having continuous pores. For example, a stamp pad can be impregnated with ink to obtain a stamp pad that supplies ink to the printing surface of a stamp that is brought into contact with the stamp pad, or a stamp can be obtained by impregnating ink into the printing material of a stamp having continuous pores.

[0113] A stamp equipped with a printing material with continuous pores is made by impregnating ink into the printing material, a rubber-like elastic body with continuous pores, and when this is pressed against a surface to be imprinted, the ink moves to the surface through the openings of the continuous pores, transferring the surface shape of the stamp. Areas where transfer is not desired are made into recesses, or the openings are closed to prevent the ink from adhering to the surface to be imprinted. The surface shape of the stamp may include a date, a symbol, or text such as "Confidential", "CONFIDENTIAL", "Completed", or "Received".

[0114] The stamp material having continuous pores is placed in a stamp base material so that its printing surface is exposed, and the exposed surface is preferably provided with a cap to prevent the ink from drying out when not in use or to prevent contamination due to accidental contact. In addition, an ink reservoir for supplying ink to the printing material may be provided at the rear of the printing material having continuous pores, thereby increasing the number of times the printing can be performed.

[0115] In addition, the printing material may be pre-impregnated with ink and then attached to the stamp, or the printing material of the stamp to which the printing material is attached may be impregnated with ink. When the printing material of the stamp to which the printing material is attached is impregnated with ink, the printing material may be impregnated with ink from the front surface or from the rear surface of the printing material. Similarly, in the case of a stamp having an ink reservoir, the ink reservoir may be filled with ink beforehand and attached to the stamp, or the ink reservoir of a stamp provided with a printing material and an ink reservoir may be filled with ink.

[0116] The stamp can form an image on various surfaces. Furthermore, the image formed by the ink for the stamp can be discolored by rubbing it with a finger or by applying the above-mentioned heating or cooling tool. The above-mentioned friction member and friction body are preferable as the heating tool, since they can be discolored by a simple method.

[0117] The above-mentioned friction member or friction body may be a member of any shape separate from the stamp, but by providing it on the stamp, it can be made highly portable. Also, a stamp set can be obtained by combining a stamp with a friction member or friction body of any shape separate from the stamp.

[0118] When applying or printing the reversible thermochromic liquid composition, the material of the support is not particularly limited and all materials are effective, for example, paper, synthetic paper, fiber, cloth, synthetic leather, leather, plastic, glass, ceramic material, metal, wood, stone, etc. The shape of the support is not limited to a flat shape, but may be uneven. A reversible thermochromic layer containing a reversible thermochromic colorant such as a reversible thermochromic composition, a reversible thermochromic microcapsule pigment or resin particles can be provided on a support to obtain a reversible thermochromic laminate (reversible thermochromic printed material). In the case of a support on which a non-thermochromic colored layer (non-thermochromic image) has already been formed, the colored layer or image can be made to disappear or appear by the reversible thermochromic layer due to a change in temperature, thereby making it possible to further diversify the manner of change.

[0119] Furthermore, a reversible thermochromic composition, a reversible thermochromic colorant such as a reversible thermochromic composition, a reversible thermochromic microcapsule pigment, or a resin particle can be melt-blended with an excipient and molded into a reversible thermochromic solid molded article for application, which can be used as a solid writing material or a solid cosmetic material. Examples of solid writing materials include crayons, pencil leads, mechanical pencil leads, solid gel markers, and the like. Examples of solid cosmetics include foundation, eyeliner, eyebrow cream, eyeshadow, lipstick, etc.

[0120] Examples of excipients used in solid writing materials include waxes, gelling agents, clays, and the like. Examples of waxes include carnauba wax, Japan wax, beeswax, microcrystalline wax, montan wax, candelilla wax, sucrose fatty acid ester, dextrin fatty acid ester, polyolefin wax, styrene-modified polyolefin wax, and paraffin wax. Examples of gelling agents include 12-hydroxystearic acid, dibenzylidene sorbitols, tribenzylidene sorbitols, amino acid oils, and alkali metal salts of higher fatty acids. Examples of clay minerals include kaolin, bentonite, and montmorillonite.

[0121] Among the above-mentioned excipients, it is preferable to contain at least one of polyolefin wax, sucrose fatty acid ester, and dextrin fatty acid ester, since these are likely to improve the writing density. Examples of polyolefin waxes include waxes such as polyethylene, polypropylene, polybutylene, α-olefin polymers, ethylene-propylene copolymers, and ethylene-butene copolymers. Furthermore, among the above polyolefin waxes, those having a softening point in the range of 100 to 130° C. and a penetration of 10 or less are preferred because they are easy to write with. If the penetration exceeds 10, the solid writing body becomes too soft, making it difficult to write with, and when the handwriting is erased, the handwriting spreads on the paper surface (the wax becomes a thin layer), which can stain the blank areas on the written surface or can easily transfer color or stain other papers. The softening point and penetration of the polyolefin wax can be measured according to the measurement method specified in JIS K2207, with a penetration value of 0.1 mm being expressed as a penetration value of 1. In other words, the smaller the penetration value of the solid writing material, the harder it is, and the larger the penetration value, the softer it is. As the sucrose fatty acid ester, an ester having a constituent fatty acid having 12 to 22 carbon atoms is preferable, and palmitic acid and stearic acid are more preferable. As the dextrin fatty acid ester, an ester having a constituent fatty acid of 14 to 18 carbon atoms is preferable, and palmitic acid, myristic acid, and stearic acid are more preferable.

[0122] In addition, side-chain crystalline polyolefin is preferred as an excipient used in solid writing materials. Here, side-chain crystalline polyolefin has a structure in which a relatively long side chain is bonded to a linear main chain. In normal linear polyolefin, the linear main chain is folded and crystallized, so melting tends to occur in a wide temperature range, whereas side-chain crystalline polyolefin crystallizes mainly in the side chain, not in the polyolefin main chain, and as a result, has the characteristics of a low melting point (Mp) and melting in a narrow temperature range. Among such side chain crystalline polyolefins, those having in the side chain a long chain alkyl group having 12 to 28 carbon atoms are particularly preferred. The long chain alkyl group in the side chain is not particularly limited and may be either linear or branched, but linear long chain alkyl groups are preferred because they provide excellent crystallinity. The alkyl group on the side chain may have a substituent, but the crystallinity is likely to decrease due to the substituent, and therefore, in order to adjust the crystallinity, the side chain of the side chain crystalline polyolefin may be modified with, for example, styrene, etc. Furthermore, if the long chain alkyl group has a functional group that forms a hydrogen bond, the long chain alkyl groups are bonded to each other by the hydrogen bond and aggregate, which improves the crystallinity, and is therefore preferable.

[0123] Side-chain crystalline polyolefins include polyolefins having a highly branched structure (hereinafter referred to as "highly branched polyolefins"), which can also be used as excipients. Highly branched polyolefins have a low melting point and melt in a narrow temperature range because the main chain is difficult to fold during crystallization.

[0124] In order to provide a solid writing material with excellent mechanical strength and thermal discoloration properties and to be easy to handle during production, the excipient preferably has a mass average molecular weight (Mw) of 2,000 to 50,000, more preferably 10,000 to 30,000. Also, the excipient preferably has a number average molecular weight (Mn) of 1,000 to 10,000. The weight average molecular weight and number average molecular weight are values ​​measured by gel permeation chromatography (GPC) using polystyrene as a standard.

[0125] The excipient is preferably blended in an amount of 0.2 to 70% by mass, more preferably 0.5 to 40% by mass, based on the total amount of the solid writing material. By blending the excipient in the above range, the shape of the solid writing material can be easily obtained, and the writing density of the solid writing material can be easily increased. If the blending ratio of the excipient exceeds 70% by mass, it becomes difficult to obtain a sufficient writing concentration, whereas if the blending ratio is less than 0.2% by mass, it becomes difficult to obtain a shape suitable for a writable core material.

[0126] Furthermore, by blending a filler into the solid writing material, it is possible to improve the strength of the solid writing material and adjust the writing feel. Examples of the filler include talc, clay, silica, calcium carbonate, barium sulfate, alumina, mica, boron nitride, potassium titanate, and glass flakes. Among the above fillers, talc or calcium carbonate is preferred because it has excellent moldability and is unlikely to impair the thermochromic properties when a reversible thermochromic microencapsulated pigment is used.

[0127] The filler is preferably blended in the range of 10 to 65% by mass based on the total amount of the solid writing material. If the blending ratio of the filler exceeds 65% by mass, the color development and writing feel tend to deteriorate. On the other hand, if the blending ratio is less than 10% by mass, the strength of the solid writing material tends to deteriorate.

[0128] Furthermore, by blending a binder resin in the solid writing material, the strength of the solid writing material can be improved. Examples of the binder resin include natural resins and synthetic resins, such as olefin resins, cellulose resins, vinyl alcohol resins, pyrrolidone resins, acrylic resins, styrene resins, amide resins, and basic group-containing resins. Among the above binder resins, ethylene-vinyl acetate copolymers, ethylene-vinyl alcohol copolymers, and polyvinyl alcohol are preferred, and the use of these resins in combination with polyester polyols can improve molding stability. The binder resin is preferably mixed in an amount of 0.5 to 5% by mass based on the total amount of the solid writing material.

[0129] In addition, by incorporating a hindered amine compound into the solid writing material, it is possible to make it difficult to visually recognize afterimages at the locations where writing marks have been erased from the writing surface, which makes it possible to satisfy re-writing properties without impairing the appearance of the writing surface, and to improve marketability. The hindered amine compound preferably has a molecular weight of 1000 or less, since it has high compatibility with other components, is less likely to bleed out, and can form clear handwritten marks even after aging. The melting point is preferably 120° C. or lower. A low melting point allows the solid writing material to be produced without applying excessive heat during production, and prevents deterioration of the reversible thermochromic colorant contained in the solid writing material, such as the reversible thermochromic composition, the reversible thermochromic microcapsule pigment, or the resin particles.

[0130] In addition, additives such as viscosity adjusters, antifungals, preservatives, antibacterial agents, UV inhibitors, antioxidants, lubricants, and fragrances may also be added, if necessary.

[0131] The solid writing material may be used alone as a writing material, or may be used as an inner core with an outer shell covering the outer periphery thereof to form a core-sheath structure (double core). The outer shell prevents the solid writing body (core) inside from being damaged by physical contact, and contributes to improving the mechanical strength of the entire solid writing body. The outer shell may or may not contain a reversible thermochromic colorant such as a reversible thermochromic composition, a reversible thermochromic microcapsule pigment, or resin particles that contributes to the formation of handwriting, but since the tip of the solid writing body is generally cut into a cone shape, the outer shell often does not affect the handwriting. Therefore, it is common not to mix a reversible thermochromic colorant into the outer shell.

[0132] The shell may contain additives such as non-thermochromic colorants, antifungal agents, preservatives, antibacterial agents, ultraviolet absorbers, antioxidants, lubricants, and fragrances, if necessary.

[0133] The solid writing material can be produced by a production method such as extrusion molding or compression molding. The above-mentioned solid writing material having a core-sheath structure in which an outer shell is provided to cover the outer surface of the inner core can be manufactured, for example, by a manufacturing method in which an outer shell is disposed on the outer surface of a lump of the inner core and compression molded using a press.

[0134] The thickness and length of the solid writing material are selected as desired depending on the purpose. For example, when the solid writing material is used as a pencil lead, the general thickness is 2.0 to 5.0 mm, preferably 2.5 to 4.0 mm. The length is 60 to 300 mm, preferably 80 to 200 mm.

[0135] In addition, when the solid writing material has a core-sheath structure, the thickness of the core and the thickness of the shell are also selected arbitrarily. A thicker shell provides better impact resistance, while a thinner shell provides more exposed core, making it easier to use. The thickness of the shell relative to the radial length of the core is preferably in the range of 10 to 100%, more preferably 20 to 50%. The thickness and length of the solid writing material are appropriately adjusted depending on the application other than pencil, for example, lead for mechanical pencils, crayons, etc.

[0136] The solid writing material can be written on various writing surfaces, and furthermore, since it uses a reversible thermochromic colorant such as a reversible thermochromic composition, a reversible thermochromic microcapsule pigment, or a resin particle, the handwriting obtained by writing on the writing surface can be discolored by rubbing with a finger or by applying the above-mentioned heating tool or cold tool. Since it can be discolored by a simple method, the above-mentioned friction member and friction body are preferable as the heating tool.

[0137] The friction member or friction body may be a member of any shape separate from the solid writing body or the exterior of the solid writing instrument in which the solid writing body is housed in an exterior container, but by providing it on the solid writing body or the exterior of the solid writing instrument in which the solid writing body is housed in an exterior container, it can be made highly portable. Specifically, examples include a form in which a friction member is provided on an exterior in the shape of a pencil, crayon, etc., made of wood or paper. In addition, a solid writing body set can be obtained by combining a solid writing body with a friction member or friction body of any shape separate from the solid writing body.

[0138] Furthermore, a reversible thermochromic composition, a reversible thermochromic colorant such as a reversible thermochromic microcapsule pigment or resin particles can be melt-blended with a thermoplastic resin, a thermosetting resin, wax, or the like to form pellets, powder, or a paste, and used as a reversible thermochromic molding resin composition. The above-mentioned reversible thermochromic molding resin composition can be subjected to general-purpose injection molding, extrusion molding, blow molding, cast molding or other means to obtain molded articles in the form of three-dimensional objects of any shape, films, sheets, plates, filaments, rods, pipes, and the like. Moreover, by melt-blending it with a thermoplastic resin, a toner or powder coating material can be obtained.

[0139] In addition, by blending a non-thermochromic colorant such as a general dye or pigment into the above-mentioned reversible thermochromic liquid composition, solid molding for coating, or resin composition for molding, the composition exhibits a color change behavior from colored (1) to colored (2).

[0140] A layer containing a light stabilizer and / or a transparent metallic luster pigment can be laminated on the above-mentioned molded body or laminate to improve light resistance, or a top coat layer can be provided to improve durability. Examples of light stabilizers include ultraviolet absorbers, antioxidants, singlet oxygen quenchers, superoxide anion quenchers, and ozone quenchers. Examples of the transparent metallic luster pigment include pigments having a core material such as natural mica, synthetic mica, glass pieces, alumina, and transparent film pieces whose surfaces are coated with a metal oxide such as titanium oxide.

[0141] Specific examples of products using the reversible thermochromic composition, microencapsulated pigment, or resin particles include the following. (1)Toys Dolls and animal-shaped toys, hair for dolls and animal-shaped toys, doll houses and furniture, clothing, doll accessories such as hats, bags, shoes, accessory toys, stuffed toys, drawing toys, toy picture books, puzzle toys such as jigsaw puzzles, building block toys, block toys, clay toys, fluid toys, tops, kites, musical instrument toys, cooking toys, gun toys, capture toys, background toys, toys imitating vehicles, animals, plants, buildings, food, etc. (2) Clothing Clothing such as T-shirts, sweatshirts, blouses, dresses, swimsuits, raincoats, skiwear, footwear such as shoes and shoelaces, cloth accessories such as handkerchiefs, towels, wrapping cloths, gloves, ties, hats, scarves, mufflers, etc. (3) Indoor decorations Carpets, curtains, curtain strings, tablecloths, rugs, cushions, carpets, rugs, chair upholstery, seats, mats, picture frames, artificial flowers, photo frames, etc. (4) Furniture Bedding such as futons, pillows, mattresses, lighting equipment, heating and cooling equipment, etc. (5) Decorations Rings, bracelets, tiaras, earrings, hair clips, false nails, ribbons, scarves, watches, glasses, etc. (6) Stationery Writing implements, stamps, erasers, writing pads, rulers, notebooks, adhesive tape, etc. (7)Daily necessities Cosmetics such as lipstick, eye shadow, foundation, eyeliner, eyebrows, nail polish, hair dye, false nails, paint for false nails, toothbrushes, etc. (8) Kitchen utensils Cups, plates, chopsticks, spoons, forks, pots, frying pans, etc. (9)Other Calendars, labels, cards, recording materials, various printed materials for preventing counterfeiting, picture books and other books, bags, packaging containers, embroidery thread, sports equipment, fishing tackle, coasters, musical instruments, hand warmers, ice packs, wallets and other bags, umbrellas, vehicles, buildings, temperature detection indicators, teaching tools, etc. EXAMPLES

[0142] Examples are shown below. In the examples, unless otherwise specified, "parts" and "%" refer to "parts by mass" and "% by mass", respectively.

[0143] <Example 101> Preparation of reversible thermochromic microencapsulated pigments As component (a), 1.5 parts of 2,6-bis(2'-ethyloxyphenyl)-4-(4'-dimethylaminophenyl)pyridine (A-1), as component (b), 4 parts of 2,4-dihydroxy-4'-tert-butylbenzophenone (I-1) and 2 parts of 1,1-bis(4-hydroxyphenyl)-2-ethylhexane (II-1) as component (c), and as component (c), 25 parts of myristyl alcohol (C-1) and 25 parts of butyl stearate (C-2) were mixed and dissolved by heating to obtain a reversible thermochromic composition that changes color reversibly. This reversible thermochromic composition was added to a mixed solution consisting of 35 parts of aromatic isocyanate prepolymer as a wall material and 40 parts of cosolvent, then emulsified and dispersed in an 8% polyvinyl alcohol aqueous solution, and stirred while heating, after which 2.5 parts of water-soluble aliphatic modified amine was added, and stirring was continued to prepare a microcapsule dispersion. From the above microcapsule dispersion, a reversible thermochromic microcapsule pigment with an average particle size of 2.0 μm was obtained by centrifugation.

[0144] <Examples 102 to 105 and Comparative Examples 101 to 104> A reversible thermochromic microcapsule pigment was obtained in the same manner as in Example 101, except that the types and amounts of components (a), (b), and (c) were changed to those shown in Table 1. The values ​​for components (a), (b), and (c) in the table indicate "parts by mass," and the values ​​for the concentration retention rates indicate "%."

[0145] [Table 1] Components (a), (b), and (c) in the table are the compounds shown below. A-1 2,6-bis(2'-ethyloxyphenyl)-4-(4'-dimethylaminophenyl)pyridine A-2 3,3-bis(2-ethoxy-4-diethylaminophenyl)-4-azaphthalide I-1 2,4-Dihydroxy-4′-tert-butylbenzophenone II-1 1,1-bis(4-hydroxyphenyl)-2-ethylhexane II-2 1,1-bis(4-hydroxyphenyl)-2-methylpropane II-3 1,1-bis(4-hydroxyphenyl) n-decane C-1 Myristyl Alcohol C-2 Butyl stearate C-3 Neopentyl stearate C-4 Capric acid 4-benzyloxyphenylethyl

[0146] [Discoloration temperature measurement] Reversible thermochromic inks were prepared by mixing 40 parts of each of the reversible thermochromic microcapsule pigments obtained in Examples 101 to 105 and Comparative Examples 101 to 104, 52 parts of ethylene-vinyl acetate copolymer resin emulsion, 5 parts of thickener, and 3 parts of leveling agent. A solid pattern was screen-printed on fine paper using the above ink to obtain a sample for measuring the discoloration temperature. Each of the above samples for measuring the discoloration temperature was set in the measurement section of a color difference meter (manufactured by Tokyo Denshoku Co., Ltd., product name: TC-3600), and the sample section was heated and cooled at a rate of 2°C / min, and the brightness value was measured as the color density at each temperature, and a color density-temperature curve was created. From the color density-temperature curve, the complete color development temperature t1, color development start temperature t2, decolorization start temperature t3, complete decolorization temperature t4, and ΔH [hysteresis width: (intermediate temperature between t3 and t4)-(intermediate temperature between t1 and t2)] were obtained. The results obtained are shown in Table 2 below. The values ​​in the table indicate "°C."

[0147] [Table 2]

[0148] [Concentration measurement] Reversible thermochromic inks were prepared by mixing 40 parts of each of the reversible thermochromic microcapsule pigments obtained in Examples 101 to 105 and Comparative Examples 101 to 104, 52 parts of an ethylene-vinyl acetate copolymer resin emulsion, 5 parts of a thickener, and 3 parts of a leveling agent. A solid pattern was screen-printed on high-quality paper using the ink to obtain a sample for density measurement. The density measurement samples of Examples 101 to 105 and Comparative Examples 101 to 104, which had been cooled to a temperature below the full color development temperature t1 and brought to a fully colored state, were set in the measurement portion of a fluorescent spectrodensitometer (manufactured by Konica Minolta, Inc., product name: FD-7 type) and the absolute density in the colored state (hereinafter referred to as "color development density") was measured. In addition, the density measurement samples of Examples 101 to 105 and Comparative Examples 101 to 104, which were heated to the complete decolorization temperature t4 or higher and made into a completely decolorized state, were set in the measurement portion of the above-mentioned fluorescence spectrodensitometer, and the absolute density in the decolorized state (hereinafter referred to as "decolorization density") was measured. The results are shown in Table 1.

[0149] [Light resistance evaluation] A reversible thermochromic ink was prepared by mixing 40 parts of each of the reversible thermochromic microcapsule pigments of Examples 101 to 105 and Comparative Examples 101 to 104, 52 parts of an ethylene-vinyl acetate copolymer resin emulsion, 5 parts of a thickener, and 3 parts of a leveling agent. A solid pattern was screen-printed on fine paper using the ink to obtain a measurement sample. Each of the above measurement samples was cooled to below the full color development temperature t1 to reach a fully colored state, and then set in the measurement section of a fluorescence spectrodensitometer (manufactured by Konica Minolta, Inc., product name: FD-7 type) to measure the absolute density in the fully colored state (hereinafter referred to as the "initial density"). Next, each measurement sample whose density was measured was heated to the complete decolorization temperature t4 or higher to make it completely decolorized, and then it was tested at 170 w / m 2 The samples were continuously exposed to light at an irradiance of 1000 nm for 30 hours. After the light irradiation, each measurement sample was taken out and cooled to below the complete color development temperature t1 to reach a completely colored state. Then, each measurement sample was set in the measurement section of the above-mentioned fluorescence spectrodensitometer, and the absolute density in the completely colored state after the light irradiation (hereinafter referred to as "density after the light irradiation") was measured. The concentration retention rate [(concentration value after light irradiation) / (initial concentration value)×100] was calculated from the initial concentration value and the concentration value after light irradiation. Note that the higher the concentration retention rate, the better the light resistance. The results are shown in Table 1.

[0150] Application example 1 Fabrication of a doll toy with hair using reversible thermochromic composite fiber Five parts of the microcapsule pigment of Example 101, one part of a dispersant, 94 parts of nylon 12 having a melting point of 180°C, and 0.1 parts of a blue general pigment were melt-mixed at 200°C in an extruder to prepare a reversible thermochromic molding resin composition in the form of pellets for the core. The above pellets were fed to an extruder for forming the core, and nylon 12 natural pellets were fed to an extruder for forming the sheath. Using a composite fiber spinning device, the fibers were spun at 200°C from 18 nozzles so that the volume ratio of core:sheath was 6:4, to prepare a reversible thermochromic composite fiber consisting of 18 single yarns with an outer diameter of 90 μm. Furthermore, the reversible thermochromic composite fiber was implanted in the head of a doll in a conventional manner to produce a doll toy equipped with hair made of the reversible thermochromic composite fiber. When the reversible thermochromic composite fiber was cooled to below 7℃ to allow the reversible thermochromic microencapsulated pigment to fully develop its color, the reversible thermochromic composite fiber showed a green color that was a mixture of the yellow from the reversible thermochromic microencapsulated pigment and the blue from the general pigment. When it was removed from the cold water, it changed from green to blue at room temperature (25℃), and when it was immersed in cold water at 7℃, it changed back to green. This change could be repeated.

[0151] Application example 2 Fabrication of a reversible thermochromic toy (reversible thermochromic miniature car) 15 parts of the microcapsule pigment of Example 102 was stirred and mixed into an oil vehicle consisting of 40 parts of an acrylic resin / xylene solution, 20 parts of xylene, 20 parts of methyl isobutyl ketone, and 5 parts of a polyisocyanate-based hardener, to prepare a reversible thermochromic liquid composition that is a paint used for spray painting. The above paint was spray-painted over the entire body of a white miniature car made of injection-molded ABS resin as a support, and then dried to provide a reversible thermochromic layer, thereby producing a reversible thermochromic miniature car. The reversible thermochromic toy was once cooled to below 12°C, and the reversible thermochromic layer was allowed to completely turn yellow. When it was then immersed in warm water at 32°C, the yellow color of the reversible thermochromic layer disappeared and it turned white. When it was removed from the warm water and immersed in cold water at 12°C, it turned yellow again. This change could be repeated.

[0152] Application example 3 Preparation of a reversible thermochromic writing implement (reversible thermochromic ballpoint pen) 25 parts of the microcapsule pigment of Example 102 (previously cooled to 12°C or less to develop a yellow color), 0.3 parts of a shear thinning agent (xanthan gum), 10 parts of urea, 10 parts of glycerin, 0.5 parts of a nonionic penetrant (manufactured by San Nopco Co., Ltd., product name: Nopco SW-WET-366), 0.1 parts of a modified silicone antifoaming agent (manufactured by San Nopco Co., Ltd., product name: Nopco 8034), 0.5 parts of a phosphate ester surfactant (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., product name: Plysurf AL), 0.5 parts of a pH adjuster (triethanolamine), 0.2 parts of a fungicide (manufactured by Lonza Japan Co., Ltd., product name: Proxel XL-2), and 52.9 parts of water were mixed to prepare a reversible thermochromic liquid composition that is an ink for writing instruments. The above-mentioned writing ink was sucked and filled into an ink reservoir made of a polypropylene pipe, and then connected to a ballpoint pen tip having a 0.5 mm diameter stainless steel ball at its tip via a resin holder. Next, a viscoelastic ink backflow prevention body (liquid plug) mainly composed of polybutene was filled into the rear end of the ink reservoir, and a tail plug was fitted to the rear of the pipe. The front and rear barrels were assembled, and a cap was fitted. After that, degassing was performed by centrifugation to produce a ballpoint pen. SEBS resin was attached to the rear end of the rear barrel as a friction member. When the above ballpoint pen was used to write on a piece of paper to form yellow letters (handwriting), the handwriting was yellow at room temperature (25° C.), and when the letters were rubbed with a friction member, the letters disappeared and became colorless, and this state could be maintained unless the paper was cooled to below 12° C. Furthermore, when the paper was placed in a refrigerator and cooled to below 12° C., the letters again turned yellow, and this color change behavior could be reproduced repeatedly.

[0153] Application example 4 Preparation of a reversible thermochromic writing implement (reversible thermochromic marking pen) 23 parts of the microcapsule pigment of Example 103 (previously cooled to -20°C or lower to develop a yellow color) was mixed with a polymer flocculant (hydroxyethyl cellulose) [manufactured by Dow Chemical Japan Co., Ltd., product name: CELLOSIZE [0.4 parts of acrylic polymer dispersant (product name: Solsperse 43000, manufactured by Lubrizol Japan Co., Ltd.)], 0.4 parts of preservative (sodium 2-pyridinethiol 1-oxide) (product name: Sodium Omadine, manufactured by Lonza Japan Co., Ltd.), 0.2 parts of preservative (3-iodo-2-propynyl N-butylcarbamate) (product name: Glykasil 2000, manufactured by Lonza Japan Co., Ltd.), 30 parts of glycerin, 0.01 parts of defoamer, 0.03 parts of pH adjuster (10% diluted phosphoric acid solution), and 45.76 parts of water were mixed into an aqueous vehicle to prepare a reversible thermochromic liquid composition that is an ink for a writing instrument. The ink reservoir, which is made of polyester sliver covered with a synthetic resin film, is impregnated with the above-mentioned ink for writing instruments, and housed in a barrel made of polypropylene resin. A resin-processed pen body (chisel type) made of polyester fiber is attached to the tip of the barrel via a resin holder, and a cap is attached to make a marking pen. The rear end of the barrel is equipped with SEBS resin as a friction member. When the above-mentioned marking pen was used to write on a piece of paper to form yellow letters (handwriting), the handwriting was yellow at room temperature (25°C), and when the letters were rubbed with a friction member, the letters disappeared and became colorless, and this state could be maintained unless the paper was cooled to below -20°C. Furthermore, when the paper was placed in a freezer and cooled to below -20°C, the letters again turned yellow, and this color change behavior could be reproduced repeatedly.

[0154] Application example 5 Fabrication of reversible thermochromic stamps A reversible thermochromic liquid composition, which is an ink for stamps, was prepared by mixing 20 parts of the microcapsule pigment of Example 103 (which had been cooled to -20°C or lower in advance to develop a yellow color), 50 parts of glycerin, 1.5 parts of an alkali-soluble acrylic emulsion (manufactured by Rohm and Haas Japan Co., Ltd., product name: Primal DR73), 0.9 parts of triethanolamine, 10 parts of a 50% aqueous solution of polyvinylpyrrolidone, 0.2 parts of a silicone-based defoamer, 0.5 parts of a penetrating leveling agent, 0.2 parts of a preservative, and 16.7 parts of water. The above-mentioned ink for stamping was impregnated into a stamp material having continuous pores, and the stamp material was fixed to a stamp base material so that the printing surface of the stamp material was exposed, and a cap was fitted to produce a stamp. The rear end of the stamp base material was equipped with SEBS resin as a friction member. When the stamp was repeatedly pressed against the surface to be imprinted (paper), the ink smoothly flowed out from the printing surface of the printing material and transferred to the surface to be imprinted, and a clear print could be continuously formed without bleeding. The print was yellow at room temperature (25°C), and when rubbed with a friction member, the print disappeared and became colorless, and this state could be maintained unless it was cooled to -20°C or lower. Furthermore, when the paper surface was placed in a freezer and cooled to -20°C or lower, the print turned yellow again, and this color change behavior could be reproduced repeatedly.

[0155] Application example 6 Preparation of a reversible thermochromic writing implement (reversible thermochromic marking pen) 20 parts of the microcapsule pigment of Example 104 (previously cooled to 11° C. or less to develop a blue-green color) was mixed with a polymer flocculant (hydroxyethyl cellulose) [manufactured by Dow Chemical Japan Co., Ltd., product name: CELLOSIZE EP-09], 0.4 parts of an acrylic polymer dispersant [manufactured by Lubrizol Japan, product name: Solsperse 43000], 0.2 parts of a preservative (sodium 2-pyridinethiol 1-oxide) [manufactured by Lonza Japan, product name: Sodium Omadine], 0.2 parts of a preservative (3-iodo-2-propynyl N-butylcarbamate) [manufactured by Lonza Japan, product name: Glykasil 2000], 18 parts of glycerin, 0.2 parts of a defoamer, 1 part of a pH adjuster (10% diluted phosphoric acid solution), 8 parts of a specific gravity adjuster (sodium polytungstate) (manufactured by SOMETU, product name: SPT), and 46.6 parts of water were mixed into an aqueous vehicle to prepare a reversible thermochromic liquid composition that is an ink for a writing instrument. The above-mentioned writing ink was impregnated into an ink occlusion body made of polyester sliver covered with a synthetic resin film, and housed in a barrel made of polypropylene resin. A resin-processed pen body (bullet type) made of an extrusion molded product of polyacetal resin having multiple ink outlet holes extending in the axial direction was connected to the tip of the barrel via a holder, and a cap was attached to produce a marking pen. SEBS resin was attached to the top of the cap as a friction member. When the marking pen was used to write on a piece of paper to form blue-green characters (handwriting), the handwriting was blue-green at room temperature (25°C), and when the characters were rubbed with a friction member, the characters disappeared and became colorless, and this state could be maintained unless the paper was cooled to below 11°C. Furthermore, when the paper was placed in a refrigerator and cooled to below 11°C, the characters again showed a color change behavior to blue-green, and this color change behavior could be repeatedly reproduced.

[0156] Application example 7 Fabrication of a mug with reversible thermochromic properties A reversible thermochromic liquid composition, which is an epoxy ink for screen printing, was prepared by mixing 30 parts of the microcapsulated pigment of Example 104, 60 parts of a hard liquid epoxy resin, 2 parts of an ultraviolet absorber, 2 parts of a thixotropy imparting agent, and 0.5 parts of an antifoaming agent, and then adding 40 parts of a room temperature curing aliphatic polyamine. The above-mentioned printing epoxy ink was printed on the side of a ceramic mug used as a support with a stainless steel screen plate using a curved printing machine to print a star pattern, and the ink was then heated and cured at 70°C for 1 hour to form a reversible thermochromic layer, producing a reversible thermochromic mug. When 11°C cold water was poured into the mug, the reversible thermochromic layer developed color and a blue-green star pattern appeared. When the cold water was removed from this state and 35°C hot water was poured in, the blue-green color of the reversible thermochromic layer disappeared and became colorless. When the hot water was removed from this state and 11°C cold water was poured in, the reversible thermochromic layer developed color and the blue-green star pattern was visible again. This change could be repeated.

[0157] Application example 8 Preparation of a reversible thermochromic writing implement (reversible thermochromic ballpoint pen) 25 parts of the microcapsule pigment of Example 105 (previously cooled to -20°C or less to develop a blue-green color), 0.3 parts of a shear thinning agent (xanthan gum), 10 parts of urea, 10 parts of glycerin, 0.5 parts of a nonionic penetrant (manufactured by San Nopco Co., Ltd., product name: Nopco SW-WET-366), 0.1 parts of a modified silicone antifoaming agent (manufactured by San Nopco Co., Ltd., product name: Nopco 8034), 0.5 parts of a phosphate ester surfactant (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., product name: Plysurf AL), 0.5 parts of a pH adjuster (triethanolamine), 0.2 parts of a fungicide (manufactured by Lonza Japan Co., Ltd., product name: Proxel XL-2), and 52.9 parts of water were mixed to prepare a reversible thermochromic liquid composition that is an ink for writing instruments. The above-mentioned writing ink was sucked and filled into an ink reservoir made of a polypropylene pipe, and then connected to a ballpoint pen tip having a 0.5 mm diameter carbide ball at its tip via a resin holder. Next, a viscoelastic ink backflow prevention body (liquid plug) mainly composed of polybutene was filled into the rear end of the ink reservoir to prepare a ballpoint pen refill. The above-mentioned refill was incorporated into the barrel to obtain a ballpoint pen (retractable ballpoint pen). The ballpoint pen has a tip attached to a ballpoint pen refill, which is stored in the barrel and exposed to the outside air, and the tip protrudes from the front end opening of the barrel by operating a clip-shaped mechanism (slide mechanism) attached to the rear side wall of the barrel. The rear end of the barrel is made of SEBS resin as a friction member. When the above ballpoint pen was used to write on a piece of paper to form blue-green characters (handwriting), the handwriting was blue-green at room temperature (25°C), and when the characters were rubbed with a friction member, the characters disappeared and became colorless, and this state could be maintained unless the paper was cooled to below -20°C. Furthermore, when the paper was placed in a freezer and cooled to below -20°C, the characters again showed a color change behavior that turned blue-green, and this color change behavior could be repeatedly reproduced.

[0158] Application example 9 Preparation of a reversible thermochromic solid writing implement 40 parts of the microcapsule pigment of Example 105, 35 parts of filler (talc), 10 parts of excipient (side chain crystalline polyolefin) [Toyokuni Oil Mill Co., Ltd., product name: HS Crystal 4100], 10 parts of excipient (polyolefin wax) [Sanyo Chemical Industries Co., Ltd., product name: Sunwax 131-P (softening point 110 ° C, needle penetration 3.5)], 2 parts of styrene-acrylic acid copolymer, 2 parts of polyvinyl alcohol, and 1 part of hindered amine light stabilizer were kneaded in a kneader to prepare a kneaded product for the inner core. Next, 69 parts of filler (talc), 10 parts of sucrose fatty acid ester, 10 parts of excipient (polyolefin wax), and 10 parts of ethylene-vinyl acetate copolymer were kneaded in a kneader to prepare a kneaded product for the outer shell. The above-mentioned kneaded material for the inner core was wrapped around the outer peripheral surface of the kneaded material for the outer shell so that the kneaded material for the inner core would become the inner core, and compression molding was performed using a press to form it into an outer diameter of φ3 mm and a length of 60 mm (the inner core was φ2 mm, and the covering thickness of the outer shell was 0.5 mm), thereby producing a solid writing body with a core-sheath structure. Note that the above dimensions are set values, and the solid writing body was manufactured by cooling to -20°C after compression molding and returning to room temperature. The solid writing body was molded and housed in a round outer shaft (wooden shaft) to obtain a pencil. A cylindrical friction body made of SEBS resin was fixed to the rear end of the pencil via a metal connecting member to produce a solid writing implement with a friction body (pencil with friction body). When the solid writing implement was used to write on paper to form blue-green characters (handwriting), the handwriting was blue-green at room temperature (25°C). When the characters were rubbed with a friction member, the characters were erased and became colorless, and this state could be maintained unless the paper was cooled to -20°C or lower. When the paper was placed in a freezer and cooled to -20°C or lower, the characters again showed a color change behavior to blue-green, and this color change behavior could be repeatedly reproduced. [Explanation of symbols]

[0159] t1 full color temperature t2 color development start temperature t3 decolorization start temperature t4 complete color erasure temperature T1 complete discoloration temperature T2 decolorization start temperature T3 color development start temperature T4 full color temperature ΔH Hysteresis width

Claims

1. (a) an electron-donating color-forming organic compound; (b) a combination of a compound represented by formula (I) and a compound represented by formula (II) as an electron accepting compound; (c) a reaction medium that causes a reversible electron donor / donor reaction between the components (a) and (b) in a specific temperature range; and comprising A reversible thermochromic composition, wherein the mass ratio of the compound represented by formula (I):the compound represented by formula (II) is 1:0.2 to 1:

4. 【Chemistry 1】 (In the formula, R １１ is a branched alkyl group having 3 to 6 carbon atoms, R １２ is a hydroxy group, n11 is 1, n12 is 1, Hydroxy groups are present at the 2nd and 4th positions of the benzene ring. 【Chemistry 2】 (In the formula, R ２１ is a hydrogen atom or a methyl group, R ２２ is a branched alkyl group having 5 to 9 carbon atoms or a phenyl group, n23 and n24 are each 0; The hydroxyl group is located at the 4-position of the benzene ring.

2. The composition according to claim 1, wherein in formula (I), R 11 is an isobutyl group, a sec-butyl group, or a tert-butyl group.

3. In formula (II), R ２２ The composition according to claim 1 or 2, wherein is a branched alkyl group having 6 to 8 carbon atoms.

4. A reversible thermochromic microencapsulated pigment comprising a composition described in any one of claims 1 to 3.

5. A reversible thermochromic liquid composition comprising the reversible thermochromic microcapsule pigment according to claim 4 and a vehicle.

6. The reversible thermochromic liquid composition according to claim 5, which is selected from the group consisting of printing ink, writing instrument ink, applicator ink, stamp ink, inkjet ink, paint, ultraviolet curing ink, paint, cosmetics, and textile coloring liquid.

7. A reversible thermochromic solid molding for coating, comprising the reversible thermochromic microcapsule pigment according to claim 4 and an excipient.

8. A reversible thermochromic solid molded article for application as described in claim 7, which is a solid writing material or a solid cosmetic material.

9. A reversible thermochromic molding resin composition comprising the reversible thermochromic microencapsulated pigment according to claim 4 and a molding resin.

10. A reversible thermochromic molded body obtained by molding the reversible thermochromic molding resin composition described in claim 9.

11. A reversibly thermochromic laminate comprising a support and a reversibly thermochromic layer comprising the reversibly thermochromic microencapsulated pigment according to claim 4.

12. A writing instrument containing the reversible thermochromic liquid composition described in claim 5.

13. A writing instrument as described in claim 12, comprising a friction member that discolors the writing made by the writing instrument due to frictional heat.

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