Reversible thermochromic composition and reversible thermochromic microcapsule pigment containing same

Abstract

The present invention addresses the problem of providing: a reversibly thermochromic composition which has excellent contrast between a color-developing state and a color-decoloring state and also has excellent light resistance; and a reversibly thermochromic microcapsule pigment which contains the reversibly thermochromic composition. The solution is a reversible thermochromic composition and a reversible thermochromic microcapsule pigment containing the reversible thermochromic composition. The reversible thermochromic composition comprises: (a) an electron-donating color-developing organic compound; (b) a combination of compounds having a specific structure as an electron-accepting compound; and (c) a reaction medium that reversibly causes an electron transfer reaction between the component (a) and the component (b) to occur in a specific temperature range.

Description

[0001] The invention of this application is a divisional application of the application with application number 202180063032.4, invention name “Reversible thermochromic composition and reversible thermochromic microcapsule pigment containing the reversible thermochromic composition” and application date September 17, 2021. Technical Field

[0002] The present invention relates to a reversible thermochromic composition and a reversible thermochromic microcapsule pigment containing the reversible thermochromic composition. More specifically, the present invention relates to a reversible thermochromic composition that changes to a decolorized state in a temperature range above a high-temperature side color change point and changes to a color developing state in a temperature range below a low-temperature side color change point and a reversible thermochromic microcapsule pigment containing the reversible thermochromic composition. Background Art

[0003] In the past, a reversible thermochromic composition has been disclosed, which has as essential components an electron-donating color-developing organic compound, an electron-accepting compound, and a reaction medium that reversibly causes an electron transfer reaction between the electron-donating color-developing organic compound and the electron-accepting compound to occur in a specific temperature range, and changes color from a color-developing state to a color-decolorizing state. For example, Patent Document 1 discloses the above-mentioned reversible thermochromic composition, and in particular, discloses that a compound of a specific structure is used alone or in combination of two or more for a color developer that is an electron-accepting compound.

[0004] The reversible thermochromic composition is required to have a high concentration in the coloring state, a low concentration in the decoloring state, and excellent contrast. Furthermore, it is required to have excellent light resistance when coloring, that is, even if it is exposed to light in the coloring state, the decrease in color concentration over time is suppressed.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2000-297277 Summary of the invention

[0008] Problems to be solved by the invention

[0009] The present invention is proposed based on the above-mentioned background technology, and aims to provide a reversible thermochromic composition having a high concentration in the coloring state and a low concentration in the decoloring state, and further having excellent light resistance, and a reversible thermochromic microcapsule pigment containing the reversible thermochromic composition.

[0010] Means for solving problems

[0011] The reversible thermochromic composition of the present invention comprises:

[0012] (a) an electron-donating color-developing organic compound;

[0013] (b) a combination of a compound represented by formula (I) and a compound represented by formula (IIa) or (IIb) as an electron accepting compound; and

[0014] (c) A reaction medium that allows the electron transfer reaction between the components (a) and (b) to occur reversibly in a specific temperature range.

[0015]

[0016] (Where,

[0017] R 11 is a hydrogen atom, or a linear or branched alkyl group having 1 to 6 carbon atoms,

[0018] L is a single bond, a linear or branched alkylene group having 1 to 3 carbon atoms, or an aryl-substituted alkylene group having 7 to 9 carbon atoms,

[0019] R 12 and R 13 each independently represents a linear or branched alkyl group having 1 to 4 carbon atoms which may be substituted with a fluorine atom, a cyclic alkyl group having 3 to 7 carbon atoms, a linear or branched alkoxy group having 1 to 3 carbon atoms, an alkenyl group having 2 to 4 carbon atoms, an aryl group having 6 to 10 carbon atoms, or a halogen atom,

[0020] R 14 each independently represents a linear or branched alkyl group having 1 to 4 carbon atoms which may be substituted with a fluorine atom, a cyclic alkyl group having 3 to 7 carbon atoms, a linear or branched alkoxy group having 1 to 3 carbon atoms, an alkenyl group having 2 to 4 carbon atoms, an aryl group having 6 to 10 carbon atoms which may be substituted with a halogen atom or a hydroxyl group, an aryl-substituted alkyl group having 7 to 11 carbon atoms which may be substituted with a halogen atom or a hydroxyl group, or a halogen atom,

[0021] n12 and n13 are each independently 0 to 3,

[0022] n14 is 0 to 3)

[0023]

[0024] (Where,

[0025] R a1 and R a2 Each independently represents a hydrogen atom, or a linear or branched alkyl group having 1 to 17 carbon atoms which may be substituted with a fluorine atom (wherein the methylene (-CH2-) group in the alkyl group may be substituted with an oxy (-O-) group or a carbonyl (-CO-) group),

[0026] R a3and R a4 are each independently a linear or branched alkyl group having 1 to 4 carbon atoms, an alkenyl group having 2 to 4 carbon atoms, or a halogen atom which may be substituted with a fluorine atom or a hydroxyl group,

[0027] na3 and na4 are each independently 0 to 2)

[0028]

[0029] (Where,

[0030] R b1 and R b2 each independently represents a hydroxyl 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, or a halogen atom,

[0031] nb1 is 0 to 3,

[0032] nb2 is 0 to 2)

[0033] The reversible thermochromic microcapsule pigment of the present invention contains the reversible thermochromic composition.

[0034] The reversible thermochromic liquid composition of the present invention comprises the reversible thermochromic microcapsule pigment and a color carrier.

[0035] The reversible thermochromic solid writing material or solid cosmetic material of the present invention comprises the reversible thermochromic microcapsule pigment and an excipient.

[0036] The reversible thermochromic molding resin composition according to the present invention comprises the reversible thermochromic microcapsule pigment and a molding resin.

[0037] The reversible thermochromic laminate according to the present invention comprises a support and a reversible thermochromic layer containing the reversible thermochromic microcapsule pigment.

[0038] The writing instrument according to the present invention contains writing instrument ink containing a reversible thermochromic microcapsule pigment and a vehicle.

[0039] Effects of the Invention

[0040] According to the present invention, it is to provide a reversible thermochromic composition having a high concentration in a colored state, a low concentration in a decolorized state, an excellent contrast between the colored state and the decolorized state, and further excellent light resistance, and a reversible thermochromic microcapsule pigment containing the reversible thermochromic composition. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1This is a diagram for explaining the hysteresis characteristics in the color density-temperature curve of a heat-decolorizable reversible thermochromic composition.

[0042] Figure 2 This is a diagram for explaining the hysteresis characteristics in the color density-temperature curve of a heat-erasable reversible thermochromic composition having color memory.

[0043] Figure 3 This is a diagram for explaining the hysteresis characteristics in the color density-temperature curve of a reversible thermochromic composition of the heating color-developing type. DETAILED DESCRIPTION

[0044] As the reversible thermochromic composition of the present invention, there can be mentioned a heat-decolorizable (decolorizes by heating and develops color by cooling) reversible thermochromic composition which contains at least the essential three components of (a) an electron-donating color-developing organic compound, (b) an electron-accepting compound, and (c) a reaction medium which determines the temperature at which the color development reaction of components (a) and (b) occurs.

[0045] As the above-mentioned reversible thermochromic composition, a reversible thermochromic composition of the heat-decolorizing type (decolorizing by heating and discoloring by cooling) described in Japanese Patent Publication No. 51-44706, Japanese Patent Publication No. 51-44707, Japanese Patent Publication No. 1-29398, etc. can be used, and the reversible thermochromic composition has the following characteristics of a relatively small hysteresis width (ΔH) (ΔH=1-7°C): the color changes before and after a predetermined temperature (color change point) as a boundary, and a decolorizing state is shown in a temperature range above the color change point on the high temperature side, and a coloring state is shown in a temperature range below the color change point on the low temperature side. Among the two states, only a specific one state exists in the normal temperature range, and the other state is maintained during the application of heat or cold heat required to express the state, but if heat or cold heat is not applied, it returns to the state presented in the normal temperature range (refer to Figure 1 ).

[0046] In addition, a reversible thermochromic composition of the heat-erasable type (decolorized by heating and colored by cooling) described in Japanese Patent Publication No. 4-17154, Japanese Patent Publication No. 7-179777, Japanese Patent Publication No. 7-33997, Japanese Patent Publication No. 8-39936, Japanese Patent Publication No. 2005-1369, etc. can also be used. The reversible thermochromic composition has a large hysteresis width (ΔH = 8 to 70° C.) and changes the color density caused by temperature change. The shape of the curve obtained by plotting the change of the temperature is that the color changes through a path that is quite different when the temperature is increased from the lower temperature side compared to the color change temperature region and when the temperature is decreased from the higher temperature side compared to the color change temperature region. The color development state in the temperature region below the complete color development temperature t1 or the color fading state in the high temperature region above the complete color fading temperature t4 has color memory in a specific temperature region [the temperature region between the color development start temperature t2 and the color fading start temperature t3 (substantially two-phase maintenance temperature region)] (refer to Figure 2 ).

[0047] Hereinafter, each of the components (a), (b), and (c) will be described in detail.

[0048] The component (a), that is, the electron-donating color-developing organic compound, is a component that determines color and is a compound that donates electrons to the component (b) as a color developer to develop color.

[0049] Examples of the electron donating color-developing organic compound include phthalide compounds, fluorane compounds, styrylquinoline compounds, diazarhodamine lactone compounds, pyridine compounds, quinazoline compounds, and bisquinazoline compounds.

[0050] Examples of the phthalide compound include diphenylmethanephthalide compounds, phenylindolylphthalide compounds, indolylphthalide compounds, diphenylmethaneazaphthalide compounds, phenylindolylazaphthalide compounds, and derivatives thereof. Among these, phenylindolylazaphthalide compounds and derivatives thereof are preferred.

[0051] In addition, examples of the fluoran compound include aminofluoran compounds, alkoxyfluoran compounds, and derivatives thereof.

[0052] The compounds that can be used as the component (a) are exemplified below.

[0053] 3,3-bis(4-dimethylaminophenyl)-6-dimethylaminophthalide,

[0054] 3-(4-diethylaminophenyl)-3-(1-ethyl-2-methylindol-3-yl)phthalide,

[0055] 3,3-Bis(1-n-butyl-2-methylindol-3-yl)phthalide,

[0056] 3,3-Bis(2-ethoxy-4-diethylaminophenyl)-4-azaphthalide,

[0057] 3-(2-ethoxy-4-diethylaminophenyl)-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide,

[0058] 3-(2-n-hexyloxy-4-diethylaminophenyl)-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide,

[0059] 3-〔2-ethoxy-4-(N-ethylanilino)phenyl〕-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide,

[0060] 3-(2-acetamido-4-diethylaminophenyl)-3-(1-propyl-2-methylindol-3-yl)-4-azaphthalide,

[0061] 3,6-bis(diphenylamino)fluoran,

[0062] 3,6-bis(N-phenyl-N-p-tolylamino)fluoran,

[0063] 3,6-Dimethoxyfluoran,

[0064] 3,6-di-n-butoxyfluoran,

[0065] 2-methyl-6-(N-ethyl-N-p-tolylamino)fluoran,

[0066] 3-Chloro-6-cyclohexylaminofluoran,

[0067] 2-methyl-6-cyclohexylaminofluoran,

[0068] 2-Chloroamino-6-di-n-butylaminofluoran,

[0069] 2-(2-chloroanilino)-6-di-n-butylaminofluoran,

[0070] 2-(3-trifluoromethylanilino)-6-diethylaminofluoran,

[0071] 2-(3-trifluoromethylanilino)-6-di-n-pentylaminofluoran,

[0072] 2-Dibenzylamino-6-diethylaminofluoran,

[0073] 2-(N-methylanilino)-6-(N-ethyl-N-p-tolylamino)fluoran,

[0074] 1,3-Dimethyl-6-diethylaminofluoran,

[0075] 2-Chloro-3-methyl-6-diethylaminofluoran,

[0076] 2-anilino-3-methyl-6-diethylaminofluoran,

[0077] 2-anilino-3-methoxy-6-diethylaminofluoran,

[0078] 2-anilino-3-methyl-6-di-n-butylaminofluoran,

[0079] 2-anilino-3-methoxy-6-di-n-butylaminofluoran,

[0080] 2-Dimethylanilino-3-methyl-6-diethylaminofluoran,

[0081] 2-anilino-3-methyl-6-(N-ethyl-N-p-tolylamino)fluoran,

[0082] 6-Diethylamino-1,2-benzofluoran,

[0083] 6-(N-ethyl-N-isobutylamino)-1,2-benzofluoran,

[0084] 6-(N-ethyl-N-isopentylamino)-1,2-benzofluoran,

[0085] 2-(3-methoxy-4-dodecyloxyphenylvinyl)quinoline,

[0086] 2-Diethylamino-8-diethylamino-4-methylspiro[5H-[1]benzopyrano[2,3-d]pyrimidine-5,1'(3'H)-isobenzofuran]-3'-one,

[0087] 2-di-n-butylamino-8-di-n-butylamino-4-methylspiro[5H-[1]benzopyrano[2,3-d]pyrimidine-5,1'(3'H)-isobenzofuran]-3'-one,

[0088] 2-Di-n-butylamino-8-diethylamino-4-methylspiro[5H-[1]benzopyrano[2,3-d]pyrimidine-5,1'(3'H)-isobenzofuran]-3'-one,

[0089] 2-di-n-butylamino-8-(N-ethyl-N-isopentylamino)-4-methylspiro[5H-[1]benzopyrano[2,3-d]pyrimidine-5,1'(3'H)-isobenzofuran]-3'-one,

[0090] 2-di-n-butylamino-8-di-n-pentylamino-4-methylspiro[5H-[1]benzopyrano[2,3-d]pyrimidine-5,1'(3'H)-isobenzofuran]-3'-one,

[0091] 4,5,6,7-tetrachloro-3-(4-dimethylamino-2-methoxyphenyl)-3-(1-n-butyl-2-methyl-1H-indol-3-yl)-1(3H)-isobenzofuranone,

[0092] 4,5,6,7-tetrachloro-3-(4-diethylamino-2-ethoxyphenyl)-3-(1-ethyl-2-methyl-1H-indol-3-yl)-1(3H)-isobenzofuranone,

[0093] 4,5,6,7-tetrachloro-3-(4-diethylamino-2-ethoxyphenyl)-3-(1-n-pentyl-2-methyl-1H-indol-3-yl)-1(3H)-isobenzofuranone,

[0094] 4,5,6,7-tetrachloro-3-(4-diethylamino-2-methylphenyl)-3-(1-ethyl-2-methyl-1H-indol-3-yl)-1(3H)-isobenzofuranone,

[0095] 3',6'-Bis[phenyl(2-methylphenyl)amino]spiro[isobenzofuran-1(3H),9'-[9H]xanthene]-3-one,

[0096] 3',6'-Bis[phenyl(3-methylphenyl)amino]spiro[isobenzofuran-1(3H),9'-[9H]xanthene]-3-one,

[0097] 3',6'-Bis[phenyl(3-ethylphenyl)amino]spiro[isobenzofuran-1(3H),9'-[9H]xanthene]-3-one,

[0098] 2,6-bis(2'-ethyloxyphenyl)-4-(4'-dimethylaminophenyl)pyridine,

[0099] 2,6-bis(2',4'-diethyloxyphenyl)-4-(4'-dimethylaminophenyl)pyridine,

[0100] 2,6-bis(2,4-diethyloxyphenyl)-4-[4-bis(4-methyloxyphenyl)aminophenyl]pyridine, 2-(4'-dimethylaminophenyl)-4-methoxyquinazoline,

[0101] 4,4'-Ethylenedioxy-bis[2-(4-diethylaminophenyl)quinazoline]

[0102] In addition, as fluorans, in addition to compounds having a substituent in the phenyl group forming the xanthene ring, there can also be compounds that have a substituent in the phenyl group forming the xanthene ring and a substituent (for example, an alkyl group such as a methyl group, a halogen atom such as a chlorine atom) in the phenyl group forming the lactone ring, which exhibit blue or black colors.

[0103] The component (b), that is, the electron-accepting compound, is a compound that accepts electrons from the component (a) and functions as a color developer for the component (a).

[0104] The component (b) is a combination of a compound represented by formula (I) and a compound represented by formula (IIa) or (IIb).

[0105] The compounds represented by formula (I) are as follows.

[0106]

[0107] In the formula,

[0108] R 11 It is a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms, and is preferably a hydrogen atom or a methyl group.

[0109] L is a single bond, a linear or branched alkylene group having 1 to 3 carbon atoms, or an aryl-substituted alkylene group having 7 to 9 carbon atoms, preferably a single bond or an ethylene group, and more preferably a single bond.

[0110] In the present invention, the aryl group also includes an aryl group substituted with an alkyl group (for example, tolyl group). The same applies to the following aryl groups.

[0111] R 12 and R 13 Each is independently a straight-chain or branched alkyl group having 1 to 4 carbon atoms which may be substituted with a fluorine atom, a cyclic alkyl group having 3 to 7 carbon atoms, a straight-chain or branched alkoxy group having 1 to 3 carbon atoms, an alkenyl group having 2 to 4 carbon atoms, an aryl group having 6 to 10 carbon atoms, or a halogen atom, preferably a straight-chain or branched alkyl group having 1 to 4 carbon atoms (more preferably a methyl group), a straight-chain or branched alkoxy group having 1 to 3 carbon atoms (more preferably a methoxy group or an ethoxy group), a cyclohexyl group, or a halogen atom (more preferably a fluorine atom).

[0112] R 14 each independently represents a linear or branched alkyl group having 1 to 4 carbon atoms which may be substituted with a fluorine atom, a cyclic alkyl group having 3 to 7 carbon atoms, a linear or branched alkoxy group having 1 to 3 carbon atoms, an alkenyl group having 2 to 4 carbon atoms, an aryl group having 6 to 10 carbon atoms which may be substituted with a halogen atom or a hydroxyl group, an aryl-substituted alkyl group having 7 to 11 carbon atoms which may be substituted with a halogen atom or a hydroxyl group, or a halogen atom,

[0113] Preferably, it is a linear or branched alkyl group having 1 to 4 carbon atoms which may be substituted with a fluorine atom, a cyclic alkyl group having 3 to 7 carbon atoms, a linear or branched alkoxy group having 1 to 3 carbon atoms, an aryl-substituted alkyl group having 7 to 11 carbon atoms which is substituted with a hydroxyl group, or a hydroxyl group.

[0114] More preferably, it is methyl, ethyl, cyclohexyl, methoxy, ethoxy, hydroxyphenyl substituted propyl, or hydroxy,

[0115] More preferably, it is a hydroxyphenyl-substituted propyl group or a hydroxy group.

[0116] n12 and n13 are each independently 0 to 3, preferably 0 or 1, and more preferably 0. n14 is 0 to 3, preferably 0 or 1. In a further preferred embodiment, the hydroxyl group is present at the 4-position (para-position) of the benzene ring.

[0117] Specific examples of (I) include the following.

[0118] 1-phenyl-1,1-bis(4-hydroxyphenyl)methane,

[0119] 1-phenyl-1,1-bis(4-hydroxyphenyl)ethane,

[0120] 4,4',4"-Methylenetriphenol,

[0121] 4,4'-〔(4-hydroxyphenyl)methylene〕bis(2-methylphenol),

[0122] 4,4'-〔(4-hydroxyphenyl)methylene〕bis(2-cyclohexyl-5-methylphenol),

[0123] 4,4',4"-Ethyltriphenol,

[0124] 4,4',4"-ethylenetri(2-methylphenol),

[0125] 4,4'-[1-{4-〔1-(4-hydroxyphenyl)-1-methylethyl〕phenyl}ethylidene]bisphenol,

[0126] 4,4'-[1-{4-〔1-(4-hydroxy-3-methylphenyl)-1-methylethyl〕phenyl}ethylidene]bis(2-methylphenol),

[0127] 4,4'-〔(3-ethoxy-4-hydroxyphenyl)methylene〕bisphenol,

[0128] 4,4'-〔3-(5-cyclohexyl-4-hydroxy-2-methylphenyl)-3-phenyl)propylene〕bis(2-cyclohexyl-5-methylphenol),

[0129] 4,4'-〔(4-hydroxyphenyl)methylene〕bis(2-isopropylphenol),

[0130] 4,4'-[1-{4-〔1-(3-fluoro-4-hydroxyphenyl)-1-methylethyl〕phenyl}ethylene]bisphenol, 4,4'-〔3-(2,5-dimethyl-4-hydroxyphenyl)butylene〕bis(2,5-dimethylphenol),

[0131] 1,1,3-Tris(4-hydroxyphenyl)propane,

[0132] 1,2,2-Tris(4-hydroxyphenyl)propane,

[0133] 1,3,3-Tris(4-hydroxyphenyl)butane,

[0134] 1,4,4-Tris(4-hydroxyphenyl)pentane,

[0135] 2,2-bis(3-methyl-4-hydroxyphenyl)-1-(4-hydroxyphenyl)propane,

[0136] 1-(3-methyl-4-hydroxyphenyl)-2,2-bis(4-hydroxyphenyl)propane,

[0137] 1-(3-methyl-4-hydroxyphenyl)-3,3-bis(4-hydroxyphenyl)butane,

[0138] 3,3-bis(3-methyl-4-hydroxyphenyl)-1-(4-hydroxyphenyl)butane,

[0139] 1,1,3-Tris(3-methyl-4-hydroxyphenyl)propane,

[0140] 1,3,3-Tris(3-methyl-4-hydroxyphenyl)butane,

[0141] 4,4'-〔4-(4-Hydroxyphenyl)-sec-butylidene〕bis(2-methylphenol)

[0142] The compounds represented by formula (IIa) are as follows.

[0143]

[0144] In the formula,

[0145] R a1 and R a2 Each independently represents a hydrogen atom, or a linear or branched alkyl group having 1 to 17 carbon atoms which may be substituted with a fluorine atom (wherein the methylene (-CH2-) group in the alkyl group may be substituted with an oxy (-O-) group or a carbonyl (-CO-) group),

[0146] Preferably, each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 11 carbon atoms which may be substituted with a fluorine atom,

[0147] More preferably R a1 and R a2 At least one of them is a linear or branched alkyl group having 5 to 9 carbon atoms,

[0148] More preferably, each independently R a1 and R a2 One of them is a branched alkyl group having 5 to 9 carbon atoms, and the other is hydrogen or methyl.

[0149] R a3 and R a4 Each is independently a straight-chain or branched alkyl group having 1 to 4 carbon atoms, an alkenyl group having 2 to 4 carbon atoms, or a halogen atom which may be substituted with a fluorine atom or a hydroxyl group, and is preferably a straight-chain or branched alkyl group having 1 to 4 carbon atoms (more preferably a methyl group), or a halogen atom (more preferably a fluorine atom).

[0150] na3 and na4 are each independently 0 to 2, preferably 0 or 1, and more preferably 0. In a further preferred embodiment, the hydroxyl group is present at the 4-position (para-position) of the benzene ring.

[0151] Specific examples of (IIa) include the following.

[0152] 1,1-bis(4-hydroxyphenyl)hexane,

[0153] 1,1-Bis(4-hydroxyphenyl)octane,

[0154] 1,1-bis(4-hydroxyphenyl)decane,

[0155] 1,1-bis(4-hydroxyphenyl)-2-methylpropane,

[0156] 1,1-bis(4-hydroxyphenyl)-2-ethylbutane,

[0157] 1,1-bis(4-hydroxyphenyl)-2-ethylhexane,

[0158] 2,2-Bis(4-hydroxyphenyl)propane,

[0159] 2,2-Bis(4-hydroxyphenyl)n-heptane,

[0160] 2,2-Bis(4-hydroxyphenyl)n-dodecane,

[0161] 2,2-bis(4-hydroxyphenyl)-4-methylhexane,

[0162] 2,2-bis(4-hydroxyphenyl)hexafluoropropane,

[0163] 2,2-bis(4-hydroxy-3-methylphenyl)butane,

[0164] 2,2-Bis(4-hydroxy-3-isopropylphenyl)propane,

[0165] 2,2-Bis(3-fluoro-4-hydroxyphenyl)propane

[0166] The compounds represented by formula (IIb) are as follows.

[0167]

[0168] In the formula,

[0169] R b1 and R b2 each independently represents a hydroxyl 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, or a halogen atom,

[0170] Preferably, it is a hydroxyl group or a linear or branched alkyl group having 1 to 8 carbon atoms,

[0171] More preferably, it is a hydroxyl group or a linear or branched alkyl group having 3 to 6 carbon atoms.

[0172] More preferably, it is a hydroxy group, an isobutyl group, a sec-butyl group, or a tert-butyl group.

[0173] nb1 is 0 to 3, preferably 1. nb2 is 0 to 2, preferably 1. In a further preferred embodiment, the hydroxyl group is present at the 2-position (ortho-position) and the 4-position (para-position) of one benzene ring.

[0174] Specific examples of (IIb) include the following.

[0175] 2,4-Dihydroxybenzophenone,

[0176] 4,4'-Dihydroxybenzophenone,

[0177] 2,4-Dihydroxy-4'-propylbenzophenone,

[0178] 2,4-Dihydroxy-4'-n-butylbenzophenone,

[0179] 2,4-Dihydroxy-4'-isobutylbenzophenone,

[0180] 2,4-Dihydroxy-4'-sec-butylbenzophenone,

[0181] 2,4-Dihydroxy-4'-tert-butylbenzophenone,

[0182] 2,4-Dihydroxy-4'-n-hexylbenzophenone,

[0183] 2,4-Dihydroxy-2',4'-dimethylbenzophenone,

[0184] 2,4-Dihydroxy-2',4',6'-trimethylbenzophenone,

[0185] 2,4-Dihydroxy-2'-methoxybenzophenone,

[0186] 2,4-Dihydroxy-4'-ethoxybenzophenone,

[0187] 2,4-Dihydroxy-2',4'-dimethoxybenzophenone,

[0188] 2,4-Dihydroxy-3',4'-diethoxybenzophenone

[0189] By combining the compound represented by formula (I) and the compound represented by formula (IIa) or (IIb) as component (b), the characteristics of each compound can be utilized, and a reversible thermochromic composition having a high color development concentration and excellent light resistance in the color development state can be provided.

[0190] Among the compounds represented by formula (IIa) and (IIb), the compound represented by formula (IIa) is preferred from the perspective of easy availability and excellent productivity. That is, as component (b), a combination of a compound represented by formula (I) and a compound represented by formula (IIa) is preferred from the perspective of color development concentration, light resistance and productivity.

[0191] Among the compounds represented by formula (I), R 11 is a hydrogen atom or a methyl group, L is a single bond or an ethylene group, n12 and n13 are each 0, n14 is 0 or 1, and when n14 is 1, R 14 A compound in which R is substituted with a methyl group, an ethyl group, a methoxy group, an ethoxy group, a hydroxyphenyl group, or a hydroxyl group, wherein the hydroxyl group is located at the 4-position (para-position) of the benzene ring. 11 is a hydrogen atom or a methyl group, L is a single bond, n12 and n13 are each 0, n14 is 0 or 1, and when n14 is 1, R 14 A compound in which a propyl group or a hydroxy group is substituted by a hydroxyphenyl group, and the hydroxy group is respectively present at the 4-position (para-position) of the benzene ring.

[0192] In view of maintaining the decolorization concentration of the reversible thermochromic composition to the same extent or lowering the decolorization concentration compared to the case where the compound represented by formula (I) is used alone as component (b), the compound represented by formula (IIa) in combination with the compound represented by formula (I) is preferably R a1 and R a2At least one of them is a linear or branched alkyl group having 5 to 9 carbon atoms, na3 and na4 are each 0, and the hydroxyl group is present at the 4-position (para-position) of the benzene ring. More preferably, each independently R a1 and R a2 A compound in which one of the groups is a branched alkyl group having 5 to 9 carbon atoms, the other is a hydrogen atom or a methyl group, na3 and na4 are each 0, and the hydroxyl group is present at the 4-position (para-position) of the benzene ring.

[0193] That is, it is most suitable to use R as the compound represented by formula (I) 11 is a hydrogen atom or a methyl group, L is a single bond, n12 and n13 are each 0, n14 is 0 or 1, and when n14 is 1, R 14 The compound wherein the hydroxyl group is substituted with a propyl group or a hydroxyl group, wherein the hydroxyl group is present at the 4-position (para-position) of the benzene ring and the compound represented by formula (IIa) are independently R a1 and R a2 A combination of compounds in which one of the groups is a branched alkyl group having 5 to 9 carbon atoms, the other is a hydrogen atom or a methyl group, n3 and n4 are each 0, and the hydroxyl group is present at the 4-position (para-position) of the benzene ring.

[0194] The mass ratio of the compound represented by formula (I): the compound represented by formula (IIa) is preferably in the range of 1:0.5 to 1:5, and more preferably in the range of 1:1 to 1:3.

[0195] When the mass ratio of the compound represented by formula (I) to the compound represented by formula (IIa) is within the above range, it is easy to obtain a reversible thermochromic composition having a large difference between the coloring concentration and the decoloring concentration, that is, an excellent contrast ratio between the coloring state and the decoloring state. In addition, when the mass ratio of the compound represented by formula (I) to the compound represented by formula (IIa) is in the range of 1:1 to 1:3, the compound represented by formula (IIa) can easily dissolve the compound represented by formula (I), thereby further improving the coloring concentration of the reversible thermochromic composition and further improving the contrast ratio between the coloring state and the decoloring state.

[0196] The component (c) of the reaction medium that causes the electron transfer reaction between the components (a) and (b) to reversibly occur in a specific temperature range will be described.

[0197] Examples of the component (c) include alcohols, esters, ketones, ethers, and acid amides.

[0198] When the reversible thermochromic composition of the present invention is applied to microencapsulation and secondary processing, low molecular weight substances evaporate outside the capsule when subjected to high heat treatment. Therefore, in order to stably hold them in the capsule, a compound having 10 or more carbon atoms is preferably used.

[0199] As the alcohol, an aliphatic monohydric saturated alcohol having 10 or more carbon atoms is effective.

[0200] As esters, esters having 10 or more carbon atoms are effective, and examples thereof include esters obtained from any combination of aliphatic and alicyclic or aromatic monocarboxylic acids and aliphatic and alicyclic or aromatic monoalcohols, esters obtained from any combination of aliphatic and alicyclic or aromatic polycarboxylic acids and aliphatic and alicyclic or aromatic monoalcohols, and esters obtained from any combination of aliphatic and alicyclic or aromatic monocarboxylic acids and aliphatic and alicyclic or aromatic polyalcohols.

[0201] In addition, ester compounds selected from esters of saturated fatty acids and branched aliphatic alcohols, esters of unsaturated fatty acids or saturated fatty acids having branches or substituents and branched or carbon-containing aliphatic alcohols, cetyl butyrate, stearyl butyrate and behenyl butyrate are also effective.

[0202] Furthermore, in order to change color with a large hysteresis characteristic with respect to the color density-temperature curve and provide color memory depending on temperature changes, carboxylic acid ester compounds showing a ΔT value (melting point-cloud point) of 5°C or more and less than 50°C as described in Japanese Patent Gazette No. 4-17154 can be exemplified.

[0203] In addition, fatty acid ester compounds obtained from an odd-numbered aliphatic monohydric alcohol having 9 or more carbon atoms 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 even-numbered aliphatic carboxylic acid having 10 to 16 carbon atoms are also effective.

[0204] As the ketones, aliphatic ketones having a total carbon number of 10 or more are effective, and aryl alkyl ketones having a total carbon number of 12 to 24 are exemplified.

[0205] As the ethers, aliphatic ethers having 10 or more total carbon atoms are effective.

[0206] Examples of the alcohols, esters, ketones, ethers, and acid amides include compounds described in JP-A-2020-100710.

[0207] Furthermore, the component (c) may be a compound represented by the following formula (1).

[0208]

[0209] [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 represents -(CH2) n OCOR2 or (CH2) nCOOR2, the other represents a hydrogen atom, n represents an integer of 0 to 2, R2 represents an alkyl group 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]

[0210] In the compound represented by formula (1), it is preferred that R1 is a hydrogen atom because a reversible thermochromic composition having a wider hysteresis width is obtained. Furthermore, it is more preferred that R1 is a hydrogen atom and m is 0.

[0211] Among the compounds represented by formula (1), the compounds represented by the following formula (2) are more preferable.

[0212]

[0213] (wherein 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)

[0214] Furthermore, the component (c) may be a compound represented by the following formula (3).

[0215]

[0216] (wherein, 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 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)

[0217] Furthermore, the component (c) may be a compound represented by the following formula (4).

[0218]

[0219] (wherein, X represents any one of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a methoxy group, and a halogen atom, m represents an integer of 1 to 3, and n represents an integer of 1 to 20)

[0220] Furthermore, the component (c) may be a compound represented by the following formula (5).

[0221]

[0222] (wherein R represents an alkyl or alkenyl group having 1 to 21 carbon atoms, and n represents an integer of 1 to 3)

[0223] Furthermore, the component (c) may be a compound represented by the following formula (6).

[0224]

[0225] (wherein, 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, m represents an integer of 1 to 3, and n represents an integer of 1 to 20)

[0226] Furthermore, the component (c) may be a compound represented by the following formula (7).

[0227]

[0228] (wherein, 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)

[0229] Furthermore, the component (c) may be a compound represented by the following formula (8).

[0230]

[0231] (wherein, 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)

[0232] Furthermore, the component (c) may be a compound represented by the following formula (9).

[0233]

[0234] (wherein, 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)

[0235] Furthermore, the component (c) may be a compound represented by the following formula (10).

[0236]

[0237] (wherein, 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)

[0238] Furthermore, the component (c) may be a compound represented by the following formula (11).

[0239]

[0240] (wherein, 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)

[0241] Furthermore, the component (c) may be a compound represented by the following formula (12).

[0242]

[0243] (wherein, 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)

[0244] Examples of the compounds represented by formulae (2) to (12) include compounds described in JP-A-2020-100710.

[0245] Among the above-mentioned components (c), compounds having one or more aromatic rings are preferred from the viewpoint of excellent solubility of component (a) in the reversible thermochromic composition, which can easily form a reversible thermochromic composition with improved color development concentration. Compounds having two or more aromatic rings among the compounds represented by formulas (1) to (12) are more preferred.

[0246] In addition, a reversible thermochromic composition of a heat-coloring type (coloring by heating and losing color by cooling) using gallic acid ester (Japanese Patent Publication No. 51-44706, Japanese Patent Publication No. 2003-253149) as an electron-accepting compound and a reversible thermochromic microcapsule pigment containing the reversible thermochromic composition (see Figure 3 ).

[0247] The reversible thermochromic composition of the present invention is a compatibilizer having the above-mentioned (a), (b), and (c) components as essential components. The ratio of each component is affected by the concentration, color change temperature, color change form, and type of each component, but in general, the mass ratio of (a) component: (b) component that can obtain the desired properties is preferably 1:0.1 to 1:100, more preferably 1:0.1 to 1:50, and further preferably in the range of 1:0.5 to 1:20.

[0248] In addition, the mass ratio of component (a) to component (c) is preferably 1:5 to 1:100, more preferably 1:5 to 1:50, further preferably 1:5 to 1:20, and particularly preferably 1:5 to 1:15. When the mass ratio of component (a) to component (c) is within the above range, it is easy to obtain a reversible thermochromic composition having a large concentration difference between the coloring concentration and the decoloring concentration, that is, a better contrast between the coloring state and the decoloring state.

[0249] Furthermore, various light stabilizers may be blended into the reversible thermochromic composition as required.

[0250] The light stabilizer is contained in order to prevent the light degradation of the reversible thermochromic composition comprising components (a), (b), and (c), and is mixed in a ratio of 0.3 to 24 parts by mass, preferably 0.3 to 16 parts by mass, relative to 1 part by mass of component (a). In addition, among the light stabilizers, the ultraviolet light absorber effectively cuts off the ultraviolet light contained in sunlight, etc., and prevents the light degradation caused by the excited state caused by the photoreaction of component (a). In addition, antioxidants, singlet oxygen quenchers, superoxide anion quenchers, ozone quenchers, etc. inhibit the oxidation reaction caused by light.

[0251] The light stabilizer may be used alone or in combination of two or more.

[0252] The reversible thermochromic composition of the present invention is effective even when used directly, but can also be encapsulated in microcapsules to form reversible thermochromic microcapsule pigments (hereinafter, sometimes referred to as "microcapsule pigments" or "pigment"), or dispersed in thermoplastic resins or thermosetting resins to form reversible thermochromic resin particles (hereinafter, sometimes referred to as "resin particles").

[0253] The reversible thermochromic composition is preferably encapsulated in microcapsules to form a reversible thermochromic microcapsule pigment. This is because the reversible thermochromic composition can be encapsulated in microcapsules to form a chemically and physically stable pigment, and further, the reversible thermochromic composition is maintained in the same composition under various use conditions and can exert the same effect.

[0254] In addition, microencapsulation has the known isocyanate-based interfacial polymerization method, melamine-formaldehyde-based in-situ polymerization method, liquid solidification coating method, phase separation method from aqueous solution, phase separation method from organic solvent, melt dispersion cooling method, gas suspension coating method, spray drying method, etc., which can be appropriately selected according to the purpose. It is also possible to further set a secondary resin film on the surface of the microcapsule according to the purpose to give durability, or modify the surface characteristics for practical use.

[0255] The reversible thermochromic microcapsule pigment preferably has a mass ratio of inner substance to wall membrane of 7:1 to 1:1. When the mass ratio of inner substance to wall membrane is within the above range, the color concentration and brightness during color development can be prevented from decreasing. More preferably, the mass ratio of inner substance to wall membrane is 6:1 to 1:1.

[0256] The average particle size of the reversible thermochromic microcapsule 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 microcapsule pigment or resin particles exceeds 50 μm, they lack dispersion stability and processing adaptability when mixed with ink, paint, or resin. On the other hand, if the average particle size is less than 0.01 μm, it is difficult to show high-concentration color development.

[0257] In addition, when microcapsule pigments or resin particles are used in ink for writing instruments, the average particle size is preferably 0.01 to 5 μm, more preferably 0.05 to 4 μm, further 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 is difficult to obtain good ink discharge properties when used in writing instruments. On the other hand, if the average particle size is less than 0.01 μm, it is difficult to show high-concentration color development.

[0258] In addition, the average particle size is measured using image analysis particle size distribution measurement software [manufactured by Macutech Co., Ltd., product name: Macbue] to determine the area of ​​the particles, and the projection area equivalent circle diameter (Heywood diameter) is calculated from the area of ​​the particle area, and the value measured is the average particle size of the particles equivalent to a sphere of equal volume based on this value.

[0259] When the particle size of all or most particles exceeds 0.2 μm, the particle size distribution can be measured as the average particle size of particles equivalent to a sphere of equal volume by the Coulter method using a particle size distribution analyzer (manufactured by Beckman Coulter Co., Ltd., product name: Multisizer 4e).

[0260] Furthermore, the volume-based particle size and average particle size may be measured using a calibrated laser diffraction / scattering particle size distribution measuring apparatus [manufactured by Horiba, Ltd., product name: LA-300] based on the values ​​measured using the above-mentioned software or a measuring apparatus adopting the Coulter method.

[0261] Reversible thermochromic compositions, reversible thermochromic microcapsule pigments, or reversible thermochromic colorants such as resin particles are dispersed in a vehicle containing water and / or an organic solvent and various additives as needed to prepare an ink composition (hereinafter sometimes referred to as "ink"), and can be used as reversible thermochromic liquid compositions such as printing inks used for screen printing, offset printing, color printing, gravure printing, coaters, pad printing, etc. / painting materials used for brush coating, spray coating, electrostatic coating, electrodeposition coating, flow coating, roller coating, dip coating, etc. / inkjet inks / ultraviolet curing inks / inks for writing tools such as markers, ballpoint pens, fountain pens, and ink pens / inks for coating tools / inks for seals / painting pigments / cosmetics / coloring liquids for fibers.

[0262] Various additives may be compounded into the reversible thermochromic liquid composition.

[0263] Examples of the additives include resins, crosslinking agents, curing agents, desiccants, plasticizers, viscosity modifiers, dispersants, ultraviolet absorbers, antioxidants, light stabilizers, anti-settling agents, lubricants, gelling agents, defoaming agents, matting agents, penetrants, pH adjusters, foaming agents, coupling agents, humectants, mildew inhibitors, preservatives, and rust inhibitors.

[0264] Examples of the writing instrument vehicle used in the writing instrument ink include an oily vehicle containing an organic solvent and an aqueous vehicle containing water and, if necessary, an organic solvent.

[0265] In the case where the vehicle is an aqueous vehicle, a water-soluble organic solvent compatible with water may be mixed in the writing instrument ink. The water-soluble organic solvent can inhibit the evaporation of water in the ink, prevent the specific gravity of the vehicle from changing, maintain good dispersion stability of the reversible thermochromic microcapsule pigment, and stabilize the structure of the loose aggregate formed by the polymer coagulant or the polymer coagulant and the dispersant described later.

[0266] Examples of the organic solvent include ethanol, propanol, butanol, glycerol, sorbitol, triethanolamine, diethanolamine, monoethanolamine, ethylene glycol, diethylene glycol, thiodiglycol, 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, cyclopentane, 2-pyrrolidone, and N-methyl-2-pyrrolidone.

[0267] When the ink for writing instruments contains a water-soluble organic solvent, the water-soluble organic solvent is preferably mixed in a range of 1 to 40% by mass, more preferably 5 to 30% by mass, and further preferably 10 to 25% by mass relative to the total amount of the ink. If the mixing ratio of the water-soluble organic solvent exceeds 40% by mass, the viscosity of the ink tends to increase. On the other hand, if the mixing ratio is less than 1% by mass, the water evaporation inhibition effect is lacking.

[0268] When the ink for writing instruments contains a water-soluble organic solvent and the hysteresis width (ΔH) of the reversible thermochromic microcapsule pigment mixed in the ink for writing instruments is large, the specific gravity of the microcapsule pigment is greater than 1. When adjusting the specific gravity of the colorant, if a water-soluble organic solvent with a specific gravity greater than water is used, the specific gravity can be easily adjusted. Therefore, as the water-soluble organic solvent, glycerin with a specific gravity exceeding 1.1 is preferably used.

[0269] A shear-reducing viscosity imparting agent may be blended into the writing instrument ink. The ink containing the shear-reducing viscosity imparting agent (shear-reducing viscosity ink) can suppress the aggregation and sedimentation of the microcapsule pigment and the bleeding of handwriting, thereby forming good handwriting.

[0270] Furthermore, when the shear-reducing viscosity ink is contained in a writing instrument in the form of a ballpoint pen, it is possible to prevent the ink from leaking out from the gap between the ball and the pen tip when the writing instrument is not in use, or to prevent the ink from flowing back when the writing tip is placed upward (in an upright position).

[0271] Examples of the shear-reducing viscosity-imparting agent include xanthan gum, welan gum, succinoglycan (average molecular weight of about 1 million to 8 million) as an organic acid-modified heteropolysaccharide whose constituent monosaccharides are glucose and galactose, alkaline gum, guar gum, locust bean gum and its derivatives, hydroxyethylcellulose, alginic acid alkyl esters, polymers having a molecular weight of 100,000 to 150,000 and containing alkyl esters of methacrylic acid as a main component, thickening polysaccharides having gelling ability extracted from seaweed such as glucomannan, agar, and carrageenan, benzylidene sorbitol and benzylidene xylitol, or any of these. Derivatives of, cross-linked acrylic polymers, inorganic fine particles, polyglycerol 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 alkylphenyl ethers, fatty acid amides and other non-ionic surfactants with an HLB value of 8 to 12, salts of dialkyl or diene sulfosuccinic acid, mixtures of N-alkyl-2-pyrrolidone and anionic surfactants, mixtures of polyvinyl alcohol and acrylic resins, etc.

[0272] In addition, a polymer flocculant may be mixed into the ink for writing instruments. The ink containing the polymer flocculant (aggregative ink) can improve the dispersibility of the microcapsule pigment because the microcapsule pigment forms loose aggregates via the polymer flocculant, which inhibits the microcapsule pigment from contacting each other and aggregating.

[0273] Examples of the polymer flocculant include polyvinyl pyrrolidone, polyethylene oxide, and water-soluble polysaccharides.

[0274] Examples of the water-soluble polysaccharides include tragacanth gum, guar gum, pullulan, cyclodextrin, and water-soluble cellulose derivatives.

[0275] Furthermore, examples of the water-soluble cellulose derivative include methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxyethyl methyl cellulose, and hydroxypropyl methyl cellulose.

[0276] Among the above-mentioned polymer flocculants, hydroxyethyl cellulose is preferred because of its excellent dispersibility.

[0277] The polymer flocculant is preferably blended in an amount of 0.1 to 1% by mass, more preferably 0.3 to 0.5% by mass, relative to the total amount of the ink. Within the above range, the microcapsule pigment can form loose aggregates, and the effect of improving the dispersibility of the pigment can be fully exhibited.

[0278] Furthermore, by blending a dispersant into the writing instrument ink, the dispersibility of the microcapsule pigment can be improved.

[0279] Furthermore, a polymer coagulant and a dispersant may be used together. When both are used together, the dispersibility of the microcapsule pigment can be improved, and the dispersibility of loose aggregates of the microcapsule pigment formed via the polymer coagulant can be further improved.

[0280] Examples of the dispersant include polyvinyl pyrrolidone, polyvinyl butyral, polyvinyl ether, styrene-maleic acid copolymer, ketone resin, hydroxyethyl cellulose and its derivatives, styrene-acrylic acid copolymer and other synthetic resins, acrylic polymers, PO / EO adducts, polyester amine oligomers, and the like.

[0281] Among the above dispersants, acrylic polymer dispersants are preferred because of their excellent dispersibility of microcapsule pigments, acrylic polymer dispersants having carboxyl groups are more preferred, and acrylic polymer dispersants having a comb-shaped structure having carboxyl groups in the side chains are further preferred.

[0282] As the dispersant, a comb-shaped acrylic polymer dispersant having a plurality of carboxyl groups in the side chain is particularly preferred, and a specific example thereof is Solspax 43000 manufactured by Lubrizol Co., Ltd. of Japan.

[0283] The dispersant is preferably mixed in a range of 0.01 to 2% by mass, more preferably 0.1 to 1.5% by mass, relative to the total amount of the ink. If the mixing ratio of the dispersant exceeds 2% by mass, the microcapsule pigment is likely to settle or float when vibration is applied from the outside. On the other hand, if the mixing ratio is less than 0.01% by mass, it is difficult to show the effect of improving dispersibility.

[0284] Furthermore, by mixing a water-soluble resin into the writing instrument ink, it is possible to impart tackiness or adhesiveness to the writing on the paper surface.

[0285] Examples of the water-soluble resin include alkyd resins, acrylic resins, styrene-maleic acid copolymers, cellulose derivatives, polyvinyl pyrrolidone, polyvinyl alcohol, and dextrin.

[0286] Among the water-soluble resins, polyvinyl alcohol is preferred because of its excellent stability as an acrylic polymer dispersant, and partially saponified polyvinyl alcohol having a saponification degree of 70 to 89 mol % is more preferred because the ink is soluble even in an acidic region.

[0287] 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.

[0288] Furthermore, when the viscosity of the vehicle used in the writing instrument ink is low, by mixing the specific gravity adjusting agent, it is possible to suppress the microcapsule pigment from settling or floating in the ink and becoming localized, thereby improving the dispersion stability of the microcapsule pigment.

[0289] The dispersion stability of the pigment is maximized when the difference in specific gravity between the vehicle and the pigment is extremely small, and the specific gravity adjuster makes the specific gravity of the vehicle close to that of the pigment. Since the specific gravity of the vehicle is affected by the specific gravity of the water-soluble substances dissolved in the vehicle and the amount added, if more specific gravity adjusters with a larger specific gravity are added to the vehicle to dissolve it, the specific gravity of the vehicle can be increased.

[0290] Examples of the specific gravity adjuster include oxyacids of Group VI elements within the atomic weight range of 90 to 185 and salts thereof.

[0291] Such a specific gravity adjuster can adjust the specific gravity of the vehicle to be close to that of the pigment having a higher specific gravity, and can suppress the pigment from settling or floating and becoming localized due to external stimulation such as vibration even if the ink has a low viscosity.

[0292] The oxyacid and its salt are selected from oxyacids of transition metal elements and their salts. The oxyacid ion is considered to form a tetrahedron or octahedron in which oxygen atoms are usually 4 or 6 coordinated to metal atoms.

[0293] The oxyacid and its salt may be a polyacid and a polyacid salt thereof. The polyacid includes isopolyacids, heteropolyacids and the like, and the polyacid salt includes isopolyacids, heteropolyacids and the like.

[0294] Examples of the specific gravity adjuster include single oxygen-containing acids and salts thereof, isopoly acids and salts thereof, heteropoly acids and salts thereof, and the like.

[0295] Examples of the single oxygen-containing acid include molybdic acid and tungstic acid. Examples of the single oxygen-containing acid salt include sodium molybdate, potassium molybdate, ammonium molybdate, sodium tungstate, potassium tungstate, ammonium tungstate, lithium tungstate, and magnesium tungstate.

[0296] Examples of the isopolyacids include metamolybdic acid, paramolybdic acid, metatungstic acid, paratungstic acid, isotungstic acid, and the like. Examples of the 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.

[0297] Examples of the heteropolyacid include phosphomolybdic acid, silicomolybdic acid, tungstophosphoric acid, and tungstosilicic acid. Examples of the heteropolyacid include sodium phosphomolybdate, sodium silicomolybdate, sodium tungstophosphoric acid, and sodium ...

[0298] The above-mentioned oxygen-containing acids and salts thereof may be used alone or in combination of two or more.

[0299] Among the above-mentioned specific gravity adjusting agents, preferred are metatungstate, paratungstate, sodium metatungstate, potassium metatungstate, ammonium metatungstate, barium metatungstate, sodium paratungstate, sodium isotungstate, tungstophosphoric acid, tungstosilicic acid, sodium tungstophosphate, and sodium tungstosilicate, and more preferred are sodium isotungstate, sodium metatungstate, and sodium paratungstate.

[0300] The above-mentioned sodium isotungstate, sodium metatungstate, and sodium paratungstate are not only highly safe but also have high specific gravity. Therefore, it is easy to adjust the high specific gravity liquid by adding the amount thereof, and they are suitable for use.

[0301] The specific gravity adjusting agent is preferably mixed in a range of 2 to 20% by mass, more preferably 5 to 15% by mass, relative to the total amount of the ink. If the mixing ratio of the specific gravity adjusting agent exceeds 20% by mass, the microcapsule pigment is easily aggregated. On the other hand, if the mixing ratio is less than 2% by mass, the specific gravity adjustment effect of the vehicle is lacking.

[0302] Furthermore, the mass ratio of the microcapsule pigment:specific gravity adjusting agent is preferably 1:0.05 to 4.0, more preferably 1:0.075 to 2.0, and even more preferably 1:0.1 to 1.5.

[0303] The color carrier mixed with the above-mentioned specific gravity adjusting agent is particularly effective for microcapsule pigments with a large specific gravity. Even if the ink has a low viscosity, it can inhibit the precipitation of the pigment in the ink when stimulation such as vibration is applied from the outside, thereby improving the dispersion stability of the microcapsule pigment.

[0304] The specific gravity of the microcapsule pigment is affected by the particle size, the components encapsulated in the microcapsule, their content, the components of the capsule wall membrane, the membrane thickness, the coloring state of the microcapsule pigment, and the temperature. However, when the microcapsule pigment is in a fully colored state, the specific gravity is 1.05 to 1.20 based on water at 20°C. Such a pigment shows a large hysteresis width (ΔH) and can maintain the decolorized state in a specific temperature range by heating. However, pigments with a large hysteresis width (ΔH) often use compounds with two or more aromatic rings in the molecule as the (c) component, so they tend to have a large specific gravity and tend to settle in the ink and be easily separated. In particular, there is a tendency for the pigment to settle and be easily separated when a stimulus such as vibration is applied from the outside. However, in the ink mixed with the above-mentioned specific gravity adjusting agent, even if the ink is low in viscosity, the microcapsule pigment can be suppressed from settling and localized, and the dispersion stability of the pigment is improved, so it is suitable for use.

[0305] Considering the dispersion stability of the pigment in the ink, when the microcapsule pigment is in a completely colored state and based on water at 20° C., the specific gravity of the microcapsule pigment is preferably 1.10 to 1.20, and more preferably 1.12 to 1.15.

[0306] In addition, the specific gravity of the microcapsule pigment can be measured by the following method.

[0307] (Method for determining specific gravity of microcapsule pigments)

[0308] 1. In a threaded tube bottle, add and mix 30 ml of glycerol aqueous solution and 1 g of fully colored microcapsule pigment to obtain a microcapsule pigment dispersion.

[0309] 2. Adjust the temperature of 30 ml of the microcapsule pigment dispersion to 20°C and centrifuge it at 1000 rpm for 30 seconds. Alternatively, a cooling / table centrifuge (manufactured by Cokusan Co., Ltd., product name: H103N) can be used as the centrifuge.

[0310] 3. Observe the microcapsule pigment dispersion.

[0311] When most of the microcapsule pigment is precipitated at the bottom of the beaker, operations 1 and 2 are repeated using an aqueous solution having a higher glycerin concentration than the current glycerin aqueous solution to observe the state of the dispersion.

[0312] When it is confirmed that most of the microcapsule pigment is suspended on the liquid surface, operations 1 and 2 are repeated using an aqueous solution having a glycerin concentration lower than that of the current glycerin aqueous solution to observe the state of the dispersion.

[0313] The above series of operations are repeated until it is visually confirmed that the liquid surface of the glycerin aqueous solution and the portion other than the vicinity of the bottom of the screw-threaded vial are uniformly colored, rather than most of the microcapsule pigment floating to the liquid surface or precipitating. The specific gravity of the glycerin aqueous solution when this state is observed is measured and is defined as the specific gravity of the microcapsule pigment. The specific gravity of the glycerin aqueous solution can be measured by subjecting the aqueous solution adjusted to 20° C. to the float method described in JIS K00617.1.

[0314] The vehicle mixed with the specific gravity adjusting agent has a specific gravity in the range of 1.00 to 1.30 at 20° C., with water as a reference substance, and the specific gravity is preferably 1.05 to 1.20, and more preferably 1.08 to 1.18.

[0315] Furthermore, the specific gravity of the vehicle is preferably 0.90 to 1.20 times, more preferably 0.95 to 1.10 times, the specific gravity of the pigment.

[0316] If the specific gravity of the colorant is within the above range, and the specific gravity of the colorant relative to the specific gravity of the pigment is within the above range, then when stimulation such as vibration is applied to the ink from the outside, even if the ink has a low viscosity, the pigment in the ink can be further suppressed from settling and localizing, thereby further improving the dispersion stability of the pigment.

[0317] When the writing instrument vehicle 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.

[0318] Furthermore, when the ink for writing instruments is used for a ballpoint pen, it is preferred to add 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 tris(alkoxycarbonylmethyl thiophosphite) and tris(alkoxycarbonylethyl thiophosphite), a phosphate monoester of a polyoxyethylene alkyl ether or a polyoxyethylene alkyl aryl ether, a phosphate diester of a polyoxyethylene alkyl ether or a polyoxyethylene alkyl aryl ether, or a lubricant such as their metal salts, ammonium salts, amine salts, or alkanolamine salts to the ink to prevent wear of the ball holder.

[0319] Furthermore, additives such as a wetting agent, a resin, resin particles, a pH adjuster, a rust preventive, a surfactant, a wetting agent, a defoaming agent, a viscosity adjuster, a preservative, and a mildew preventive may be blended as necessary.

[0320] The reversible thermochromic microcapsule pigment is preferably mixed in the writing instrument ink in an amount of 5 to 40% by mass, more preferably 10 to 40% by mass, and further preferably 10 to 30% by mass relative to the total amount of the ink. The mixing ratio of the microcapsule pigment is within the above range, so that the desired color concentration can be obtained and the reduction in the outflow of the ink can be prevented.

[0321] The ink composition of the present invention can be produced by any conventionally known method. Specifically, the above-mentioned components can be mixed in necessary amounts and mixed using various stirrers such as propeller stirring, homodispersing machine or homomixer, and various dispersers such as bead mill.

[0322] When the writing instrument ink according to the present invention is used in a ballpoint pen, the viscosity thereof is 20° C. at a rotation speed of 1 rpm (shear rate of 3.84 seconds). -1 ), from the viewpoint of suppressing the sedimentation or aggregation of the microcapsule pigment, it is preferably 1 to 2000 mPa·s, more preferably 3 to 1500 mPa·s, and still more preferably 500 to 1000 mPa·s. In addition, under an environment of 20°C, at a rotation speed of 100 rpm (shear rate of 384 sec -1), the viscosity is preferably 1 to 200 mPa·s, more preferably 10 to 100 mPa·s, and further preferably 20 to 50 mPa·s, from the viewpoint of good ink discharge from the tip of a ballpoint pen. When the viscosity is within the above range, the dispersion stability of the microcapsule pigment and the fluidity of the ink in the mechanism of the ballpoint pen can be maintained at a high level.

[0323] The viscosity was measured using a rheometer (manufactured by TA Instruments, product name: Discovery HR-2, cone and plate (diameter 40 mm, angle 1°)) in which the ink was placed in an environment of 20°C and rotated at 1 rpm (shear rate 3.84 sec -1 ), or rotation speed 100 rpm (shear speed 384 seconds -1 ) under the conditions of

[0324] When the writing instrument ink according to the present invention is used for a ballpoint pen, its surface tension is preferably 20 to 50 mN / m, more preferably 25 to 45 mN / m at 20° C. When the surface tension is within the above range, it is easy to suppress the bleeding of the writing line and the print-through to the paper surface, and the wettability of the ink to the paper surface can be improved.

[0325] The surface tension is a value measured by a surface tension meter (product name: DY-300, manufactured by Kyowa Interface Science Co., Ltd.) by a vertical plate method using a platinum plate while leaving the ink in an environment at 20°C.

[0326] When the writing instrument ink according to the present invention is used in a ballpoint pen, the pH is preferably 3 to 10, more preferably 4 to 9. When the pH is within the above range, aggregation or precipitation of the microcapsule pigment contained in the ink in a low temperature region can be suppressed.

[0327] The pH is a value measured by leaving the ink in an environment of 20° C. using a pH meter (manufactured by Toadie Keker Co., Ltd., product name: IM-40S).

[0328] When the writing instrument ink according to the present invention is used for a marker pen, the viscosity thereof is preferably 1 to 20 mPa·s, more preferably 1 to 10 mPa·s, and further preferably 1 to 5 mPa·s when measured at 20° C. and 30 rpm. When the viscosity is within the above range, the fluidity of the ink and the dispersion stability of the microcapsule pigment can be improved.

[0329] The viscosity is a value measured by leaving 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).

[0330] When the writing instrument ink according to the present invention is used for a marker pen, its surface tension is preferably 25 to 50 mN / m, more preferably 25 to 45 mN / m, and further preferably 35 to 45 mN / m at 20° C. When the surface tension is within the above range, it is easy to suppress the bleeding of the writing line and the print-through to the paper surface, and the wettability of the ink to the paper surface can be improved.

[0331] The surface tension is a value measured by a surface tension meter (product name: DY-300, manufactured by Kyowa Interface Science Co., Ltd.) by a vertical plate method using a glass plate in an environment of 20°C.

[0332] When the writing instrument ink according to the present invention is used for a marker pen, the pH is preferably 3 to 8, more preferably 4 to 7, and even more preferably 5 to 6. When the pH is within the above range, aggregation or precipitation of the microcapsule pigment contained in the ink in a low temperature region can be suppressed.

[0333] The pH is a value measured by leaving the ink in an environment of 20° C. using a pH meter (manufactured by Toadie Keker Co., Ltd., product name: IM-40S).

[0334] The writing tool ink is contained in a writing tool including a writing tip and an ink filling mechanism.

[0335] Examples of the writing implement include various writing implements such as a ballpoint pen, a marker pen, a fountain pen, an ink pen, and a calligraphy pen.

[0336] There are no particular limitations on the pen tip of the writing tool, and pen tips having various nibs can be used.

[0337] As a ballpoint pen tip among various nibs, there can be exemplified a pen tip in which a ball is held by a ball holding portion which is formed by pressing and deforming the vicinity of the front end of a metal tube from the outside toward the inside, a pen tip in which a ball is held by a ball holding portion which is formed by cutting a metal material using a drill or the like, a pen tip in which a resin ball holder is provided inside a metal or plastic pen tip, or a pen tip in which the ball held by the above pen tip is pushed forward by a spring body, etc.

[0338] The material of the ballpoint pen tip and the ball is not particularly limited, and examples thereof include cemented carbide (superhard), stainless steel, ruby, ceramic, resin, rubber, and the like.

[0339] The diameter of the beads 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 beads may also be subjected to surface treatment such as DLC coating.

[0340] As the tip of a marker pen, there can be exemplified a resin processed body of fiber, a fusion processed body of heat-fusible fiber, a felt body, and the like, which are porous members having interconnected pores with a porosity selected from a range of approximately 30 to 70%, or an extruded body of a synthetic resin having a plurality of ink outlet holes extending axially, one end of which is processed into a shape corresponding to the purpose, such as a shell shape, a rectangular shape, a wedge shape, or the like, for practical use.

[0341] In addition, as the pen tip (pen body) in the form of a fountain pen, for example, a metal plate such as a stainless steel plate or a gold alloy plate is cut into a tapered shape at the front end, a bent or curved pen tip, a resin-molded pen tip shape, etc. In addition, a slit may be provided in the center of the pen body, or a ball portion may be provided at the front end.

[0342] As the ink filling mechanism, for example, an ink container or an ink storage body that can directly fill the writing instrument with ink can be exemplified.

[0343] The ink container is made of a molded body or a metal tubular body made of a thermoplastic resin such as polyethylene, polypropylene, polyethylene terephthalate, or nylon, and the ink container and the pen tip may be connected directly or via a connecting member.

[0344] The ink storage body is a fiber bundle body in which crimped fibers are bundled in the longitudinal direction, and the crimped fibers are stored in a covering body such as a plastic cylinder or a film, and the porosity is adjusted to a range of about 40 to 90%.

[0345] When a ballpoint pen is filled with writing ink, the structure and shape of the ballpoint pen itself are not particularly limited. For example, a ballpoint pen may be provided which has an ink container filled with shear-reducing viscosity ink in a barrel, the ink container being connected to a ballpoint pen tip with a ball mounted at the front end, and a liquid plug for preventing backflow being closely attached to the end face of the ink.

[0346] The ink backflow prevention body composition is filled at the rear end of the ink filled in the ink container.

[0347] The ink backflow prevention body composition is composed of a non-volatile liquid and / or a low-volatile liquid, and examples thereof include petrolatum, spindle oil, castor oil, olive oil, refined mineral oil, liquid paraffin, polybutene, α-olefins, oligomers or copolymers of α-olefins, dimethyl silicone oil, methylphenyl silicone oil, amino-modified silicone oil, polyether-modified silicone oil, and fatty acid-modified silicone oil.

[0348] The ink backflow prevention body composition can be used alone or in combination of two or more as appropriate.

[0349] It is preferred to add a thickener to the ink backflow prevention body composition to thicken it to a suitable viscosity.

[0350] Examples of the thickener include silica having a surface subjected to a hydrophobic treatment, fine-particle silica having a surface subjected to a methylation treatment, aluminum silicate, swelling mica, hydrophobicized bentonite, montmorillonite and other clay-based thickeners, fatty acid metal soaps such as magnesium stearate, calcium stearate, aluminum stearate, and zinc stearate, tribenzylidene sorbitol, fatty acid amide, amide-modified polyethylene wax, hydrogenated castor oil, dextrin-based compounds such as fatty acid dextrin, and cellulose-based compounds.

[0351] Furthermore, the above-mentioned liquid ink backflow preventing body composition and a solid ink backflow preventing body composition may be used in combination.

[0352] Furthermore, the barrel itself may serve as the ink filling mechanism, and an example of a ballpoint pen in which the barrel is directly filled with ink and a ballpoint pen tip is attached to the front end of the barrel.

[0353] The ballpoint pen including the ballpoint pen tip and the ink filling mechanism may further include an ink supply mechanism for supplying the ink filled in the ink filling mechanism to the pen head.

[0354] The ink supply mechanism is not particularly limited, and examples thereof include: (1) a mechanism comprising an ink induction core formed of a fiber bundle or the like as an ink flow regulator for supplying ink to a pen tip; (2) a mechanism comprising a comb-groove-shaped ink flow regulator for supplying ink to a pen tip through the interposition of the comb-groove-shaped ink flow regulator; and (3) a mechanism comprising a pen core having an ink induction core for guiding ink from an ink filling mechanism to a pen tip along an axis, wherein the ink induction core is arranged in parallel with a plurality of disc bodies with comb-groove-shaped intervals opened therebetween, and wherein a slit-shaped ink induction groove is provided that penetrates the disc body axially and a ventilation groove that is wider than the slit-shaped ink induction groove, and wherein the pen core has an ink induction core for guiding ink along the axis from an ink filling mechanism to a pen tip.

[0355] 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 a plurality of disc bodies are in a comb-shaped groove. Examples of the synthetic resin include general-purpose polycarbonate, polypropylene, polyethylene, acrylonitrile-butadiene-styrene copolymer (ABS resin), etc. In particular, acrylonitrile-butadiene-styrene copolymer (ABS resin) is suitable for use because of its high moldability and ease of obtaining pen core performance.

[0356] When the ballpoint pen includes the ink supply mechanism, the ink storage body described above may be used as the ink filling mechanism in addition to the ink container and the barrel.

[0357] As the structure of a ballpoint pen for storing writing ink, specifically, there can be exemplified (1) a ballpoint pen in which the ballpoint pen tip is connected to an ink container directly or via a connecting member, and a ballpoint pen refill formed by filling the writing ink and filling the end surface of the ink with an ink backflow prevention body is stored in the barrel; (2) a ballpoint pen in which the writing ink is directly filled in the barrel and has a mechanism for supplying ink to the nib by interposing a comb-groove-shaped ink flow regulating body or an ink induction core composed of fiber bundles as the ink flow regulating body; (3) a ballpoint pen in which the writing ink is directly filled in the barrel and has a mechanism for supplying ink to the nib via the above-mentioned refill; (4) a ballpoint pen in which an ink storage body composed of a fiber bundle impregnated with writing ink is stored in the barrel and has a mechanism for supplying ink to the nib by interposing an ink induction core composed of fiber bundles as the ink flow regulating body.

[0358] When a marker pen is filled with writing ink, the structure and shape of the marker pen itself are not particularly limited, and an example of a marker pen having an ink occlusion body filled with agglutinative ink in a barrel, the ink occlusion body being connected to the marker pen tip, can be mentioned.

[0359] In addition to directly connecting the pen tip and the ink storage body, the ink storage body and the pen tip may be connected via a connecting member.

[0360] The marking pen including the marking pen tip and the ink filling mechanism may further include an ink supply mechanism for supplying the ink filled in the ink filling mechanism to the pen tip.

[0361] The ink supply mechanism is not particularly limited, and for example, in addition to the ink supply mechanism of the above-mentioned ballpoint pen, there can be mentioned (4) a mechanism having an ink flow regulator using a valve mechanism, which supplies ink to the pen tip by opening the valve.

[0362] The valve mechanism may be a conventionally used pumping type that is opened by pressing the pen tip, and it is suitable to set the spring pressure so that it can be pressed and opened by the pen pressure.

[0363] When the marker pen has an ink supply mechanism, as an ink filling mechanism, in addition to the above-mentioned ink occlusion body, an ink receiving body that can be directly filled with writing tools ink can also be used. In addition, the shaft cylinder itself can be made into an ink filling mechanism, which can directly fill the writing tools ink.

[0364] As the structure of the marking pen for accommodating writing ink, specifically, there can be exemplified (1) a marking pen in which an ink occluding body composed of a fiber bundle impregnated with writing ink is accommodated in a barrel, and a marking pen tip composed of a fiber processed body or a resin molded body with capillary gaps is connected to the barrel directly or via a connecting member in such a manner that the ink occluding body and the tip are connected; (2) a marking pen in which the barrel is directly filled with writing ink, and a mechanism is provided for supplying ink to the pen tip through a comb-groove-shaped ink flow regulating body or an ink inducing core composed of a fiber bundle as the ink flow regulating body; (3) (4) a marking pen having a pen tip and an ink container via a valve mechanism that opens the valve by pressing the pen tip, and the ink container is directly filled with writing ink; (5) a marking pen having a marking pen tip composed of a fiber processed body or a resin molded body with capillary gaps connected to the pen tip directly by an ink storage body or via a connecting member to an ink storage body that contains an ink storage body composed of a fiber bundle impregnated with writing ink, and a marking pen refill is housed in the barrel, etc.

[0365] Further, the ballpoint pen or the marker pen may be made into a detachable structure and become an ink bag form. In this case, the ink bag can be replaced with a new ink bag and used after the ink contained in the ink bag of the writing instrument is used up.

[0366] As the ink bag, a material that is connected to the writing tool body to form the shaft barrel of the writing tool, and a material that is connected to the writing tool body and covers the shaft barrel (rear shaft) for protection are used. In addition, in the latter, in addition to being used as a single ink bag, the writing tool body and the ink bag are connected in the writing tool before use, and the material is accommodated in the shaft barrel in a non-connected state so that the user of the writing tool can connect the ink bag in the shaft barrel when using it and start using it.

[0367] In addition, when a ballpoint pen or a marker is directly filled with ink for writing tools, in order to make the redispersion of the microcapsule pigment easy, preferably in the ink container or the shaft cylinder filled with ink, a stirring body such as a stirring ball for stirring the ink is built-in. As the shape of the stirring body, a spherical body and a rod-shaped body can be enumerated. As the material of the stirring body, it is not particularly limited, and examples such as metal, ceramics, resin, glass, etc. can be given.

[0368] Furthermore, it is preferred to provide a cap installed in a manner to cover the writing tip (tip tip) in a writing tool such as a ballpoint pen or a marker pen, or to provide a telescopic mechanism by which the writing tip can be extended and retracted from the writing tool body (shaft tube). This can prevent the writing tip from drying out and becoming incapable of writing, or prevent the writing tip from being contaminated / damaged.

[0369] Any writing instrument provided with a telescopic mechanism can be used as long as the writing tip is housed in the barrel with the writing tip exposed to the outside air and the writing tip protrudes from the barrel opening due to the operation of the telescopic mechanism. For example, the above-mentioned ballpoint pen refills or marker pen refills can be made into a structure in which the refill is housed in the barrel and the writing tip protrudes from the barrel opening due to the operation of the telescopic mechanism, thereby making it possible to manufacture a writing instrument provided with a telescopic mechanism (telescopic writing instrument).

[0370] In addition, when a telescopic mechanism is provided on the writing tool, a plurality of ballpoint pen refills or marker pen refills can be accommodated in the barrel to form a composite telescopic writing tool (a telescopic ballpoint pen or a telescopic marker pen) in which the writing tip of any refill can be telescoped from the opening of the barrel through the operation of the telescopic mechanism.

[0371] Examples of the telescopic mechanism include: (1) a side sliding telescopic mechanism in which an operating portion (pen clip) capable of moving in the front-rear direction from the rear side wall of the barrel is protruded radially outward, and the operating portion is slid forward to allow the writing tip to be telescoped from the front end opening of the barrel; (2) a rear end knocking telescopic mechanism in which an operating portion arranged at the rear end of the barrel is pressed forward to allow the writing tip to be telescoped from the front end opening of the barrel; (3) a side knocking telescopic mechanism in which an operating portion protruding from the outside of the side wall of the barrel is pressed radially inward to allow the writing tip to be telescoped from the front end opening of the barrel; (4) a rotating telescopic mechanism in which an operating portion at the rear of the barrel is rotated to allow the writing tip to be telescoped from the front end opening of the barrel, etc.

[0372] Furthermore, the shape of ballpoint pens and marker pens is not limited to the above-mentioned structure. In addition to installing pen tips of different shapes or pen heads that can discharge ink of different tones, it is also possible to install pen tips of different shapes and provide composite writing tools (two-headed type, protruding pen head type, etc.) in which the tones of ink discharged from each pen tip are different.

[0373] The handwriting obtained by writing on the writing surface using the writing implement containing the above-mentioned writing implement ink can be changed in color by rubbing with fingers, heating the implement, or cooling the implement.

[0374] As heating tools, there can be cited electric heating color-changing tools equipped with resistance heating elements such as PTC elements, heating color-changing tools filled with media such as warm water, heating color-changing tools using steam, laser, etc., the use of hair dryers, etc., but considering that the color can be changed by a simple method, friction components and friction bodies are preferred.

[0375] Examples of the cooling tool include an electrically conductive hot and cold color changing tool using a Peltier element, a hot and cold color changing tool filled with a cooling medium such as cold water or ice flakes, and applications of a cold storage agent, a refrigerator, and a freezer.

[0376] As friction members and friction bodies, preferably, elastic bodies such as elastomers and plastic foams are used which are elastic and can generate friction heat by generating moderate friction when rubbing. However, plastic molded bodies, stone, wood, metal, cloth, etc. can also be used.

[0377] In addition, although a general eraser for erasing pencil marks can be used to erase the marks, since scraps are generated when erasing, it is suitable to use the above-mentioned friction member and friction body that hardly generate scraps.

[0378] The material of the friction member and the friction body may be, for example, silicone resin, SEBS resin (styrene-ethylene-butadiene-styrene block copolymer), etc. Since silicone resin has a tendency to easily adhere to the part removed by rubbing, and the handwriting is repelled when writing repeatedly, SEBS resin is more suitable.

[0379] The above-mentioned friction member or friction body can also be a member of any shape separated from a writing tool, but by being arranged on the writing tool, thereby can make excellent portability. In addition, the writing tool and the friction member or friction body of any shape separated from the writing tool can also be combined to obtain a writing tool kit.

[0380] In the case of a writing instrument with a cap, the location where the friction member or friction body is set is not particularly limited. For example, the cap itself can be formed by the friction member, or the shaft tube itself can be formed by the friction member, or the pen clip itself can be formed by the friction member when a pen clip is provided, or the friction member or friction body can be provided at the front end (top) of the cap or the rear end of the shaft tube (the part where the writing front end is not provided).

[0381] When the writing tool is a telescopic writing tool, the location where the friction member or friction body is set is not particularly limited. For example, the shaft cylinder itself can be formed by the friction member, or the pen clip itself can be formed by the friction member when a pen clip is further provided, or the friction member or friction body can be provided near the opening of the shaft cylinder, at the rear end of the shaft cylinder (the part where the writing front end is not provided), or at the striking part.

[0382] Furthermore, the above-mentioned ink can also be used as seal ink.

[0383] As the medium of the seal ink, water is used, but a water-soluble organic solvent may be used as necessary.

[0384] When a microcapsule pigment is used in the stamp ink, glycerin or propylene glycol is preferred among water-soluble organic solvents.

[0385] The water-soluble organic solvent is preferably mixed in a range of 30 to 60% by mass, more preferably 30 to 55% by mass, and further preferably 40 to 50% by mass relative to the total amount of the ink. When the mixing ratio of the water-soluble organic solvent is within the above range, the ink will not dry or absorb moisture, and a clear print will be easily obtained.

[0386] If the mixing ratio of the water-soluble organic solvent exceeds 60% by mass, then hygroscopicity is easy to become high, and the imprint is infiltrated, or unevenness occurs, and therefore it is difficult to obtain a distinct imprint. On the other hand, if the mixing ratio is less than 30% by mass, then the stamp face is dry, and the imprint is sparse, and it is difficult to obtain a distinct imprint.

[0387] Furthermore, an organic solvent may also be used as the above-mentioned medium.

[0388] Examples of the organic solvent include castor oil fatty acid alkyl esters, cellosolve-based solvents, alkylene glycol-based solvents, ester-based solvents, hydrocarbon-based solvents, halogenated hydrocarbon-based solvents, alcohol-based solvents, ether-based solvents, ketone-based solvents, propionic acid-based solvents, high-polarity solvents, and mixed solvents thereof.

[0389] Furthermore, a thickener may be blended into the stamp ink. Among the thickeners, an alkali-soluble acrylic emulsion is preferred.

[0390] 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.

[0391] Furthermore, by adding a binder resin to the stamp ink, it is possible to improve the adhesion of the stamp or adjust the viscosity of the ink.

[0392] Examples of the binder resin include resin emulsions, alkali-soluble resins, and water-soluble resins.

[0393] Furthermore, additives such as a wetting agent, a resin, resin particles, a pH adjuster, a rust preventive, a surfactant, a wetting agent, a defoaming agent, a viscosity adjuster, a preservative, and a mildew preventive may be blended as necessary.

[0394] In the stamp ink, the reversible thermochromic microcapsule pigment is preferably mixed in the range of 10 to 40% by mass, more preferably 10 to 35% by mass, and further preferably 10 to 30% by mass relative to the total amount of the ink. If the mixing ratio of the microcapsule pigment exceeds 40% by mass, the dispersion stability of the microcapsule pigment in the ink is easily reduced. On the other hand, if the mixing ratio is less than 10% by mass, the color development concentration is easily reduced.

[0395] The seal ink described above can be used as an ink for an ink pad or a seal ink having a seal material having continuous pores.

[0396] For example, ink is impregnated in the ink pad, and an ink pad supplying ink to the stamp face of the stamp in contact can be obtained. In addition, the stamp can also be obtained by impregnating the stamp material of the stamp having a stamp material with continuous pores with ink.

[0397] The stamp can form an imprint on various stamped surfaces. Furthermore, the imprint formed by the stamp ink can be changed in color by rubbing with fingers or using the heating tool or the hot and cold tool. The friction member and the friction body are preferably used as the heating tool because they can be changed in color by a simple method.

[0398] The friction member or the friction body can be a member of any shape separated from the seal, but can be provided on the seal to make excellent portability. In addition, the seal and the friction member or the friction body of any shape separated from the seal can be combined to obtain the seal kit.

[0399] When coating or printing a reversible thermochromic liquid composition, the material of the support is not particularly limited and all are effective, and examples thereof include paper, synthetic paper, fiber, cloth, synthetic leather, leather, plastic, glass, ceramic material, metal, wood, stone, etc.

[0400] The shape of the support is not limited to a planar shape, and may be a concave-convex shape.

[0401] By providing a reversible thermochromic layer containing a reversible thermochromic colorant on a support, a reversible thermochromic laminate (reversible thermochromic printed material) can be obtained.

[0402] When a non-thermochromic coloring layer (non-thermochromic image) is formed in advance on a support, the coloring layer or image can be made to appear and disappear through the reversible thermochromic layer by temperature change, thereby further diversifying the appearance of the change.

[0403] Furthermore, by melt-blending the reversibly thermochromic colorant with an excipient and then molding the mixture, a reversibly thermochromic solid molded article for coating can be prepared and used as a solid writing material or a solid cosmetic.

[0404] Examples of the solid writing material include crayons, pencil leads, mechanical pencil leads, solid gel markers, and the like.

[0405] Examples of the solid cosmetic include foundation, eyeliner, eyebrow pencil, eye shadow, lipstick and the like.

[0406] Examples of excipients used for solid writing materials include waxes, gelling agents, and clay minerals.

[0407] In order to easily improve the density of handwriting, the excipient preferably contains at least one of polyolefin wax, sucrose fatty acid ester, or dextrin fatty acid ester.

[0408] In addition, from the perspective of excellent mechanical strength and thermochromic properties of the solid writing body and easy handling during production, the excipient is preferably a substance with a mass average molecular weight (Mw) of 2,000 to 50,000, more preferably a substance with a mass average molecular weight (Mw) of 10,000 to 30,000. In addition, a substance with a number average molecular weight (Mn) of 1,000 to 10,000 is preferred.

[0409] In addition, the mass average molecular weight and the number average molecular weight are values ​​measured by gel permeation chromatography (GPC) using polystyrene as a standard.

[0410] The excipient is preferably mixed in the range of 0.2 to 70% by mass, more preferably 0.5 to 40% by mass, relative to the total amount of the solid writing material. When the mixing ratio of the excipient is within the above range, the shape of the solid writing material is easily obtained, and the handwriting density of the solid writing material is easily increased.

[0411] If the blending ratio of the excipient exceeds 70% by mass, it is difficult to obtain a sufficient writing density. On the other hand, if the blending ratio is less than 0.2% by mass, it is difficult to obtain a shape that can be used as a core material for writing.

[0412] In addition, by mixing fillers into the solid writing material, the strength of the solid writing material can be improved and the writing feel can be adjusted.

[0413] Among the above fillers, talc or calcium carbonate is preferred because they are excellent in moldability and are less likely to impair the thermochromic properties when a microcapsule pigment is used.

[0414] The filler is preferably mixed in a range of 10 to 65% by weight relative to the total amount of the solid writing material. If the mixing ratio of the filler exceeds 65% by weight, the color development and writing feel are likely to decrease. On the other hand, if the mixing ratio is less than 10% by weight, the strength of the solid writing material is likely to decrease.

[0415] Furthermore, by mixing a binder resin into the solid writing material, the strength of the solid writing material can be improved.

[0416] Among the binder resins, ethylene-vinyl acetate copolymers, ethylene-vinyl alcohol copolymers, and polyvinyl alcohol are preferred. By using these resins in combination with polyester polyol, molding stability can be improved.

[0417] The binder resin is preferably blended in an amount within a range of 0.5 to 5% by mass based on the total amount of the solid writing material.

[0418] In addition, by mixing a hindered amine compound into a solid writing medium, the residual image of the position where the handwriting is removed from the written surface can be made difficult to recognize. Therefore, the beauty of the written surface is not damaged, and the rewritability can be made satisfactory, which can improve the commercial value.

[0419] Furthermore, additives such as a viscosity modifier, a mildew preventer, a preservative, an antibacterial agent, an ultraviolet light inhibitor, an antioxidant, a lubricant, and a fragrance may be blended as necessary.

[0420] The solid writing material can be used alone as a writing material, or it can be used as an inner core to form a core-sheath structure (double core) with an outer shell covering its outer peripheral surface.

[0421] The casing may also contain additives such as a non-thermochromic colorant, a mildew preventer, a preservative, an antibacterial agent, an ultraviolet absorber, an antioxidant, a lubricant, and a fragrance, as required.

[0422] The solid writing body can be used to write on various writing surfaces. Furthermore, since a reversible thermochromic colorant is used, the handwriting obtained by writing on the writing surface can change color by rubbing with fingers or using the heating tool or the hot and cold tool. The friction member and the friction body are preferably used as the heating tool because they can change color by a simple method.

[0423] The friction member or friction body may be a member of any shape that is separate from the solid writing body or the outer casing of a solid writing tool that contains the solid writing body, but by being provided on the solid writing body or the outer casing of a solid writing tool that contains the solid writing body, the portability can be improved. Specifically, there may be a form in which a friction member is provided in the shape of a pencil, crayon, etc., the outer casing of which is made of wood, paper, etc. In addition, a solid writing body and a friction member or friction body of any shape that is separate from the solid writing body may be combined to obtain a solid writing body kit.

[0424] Furthermore, the reversible thermochromic colorant can be melt-blended with a thermoplastic resin, a thermosetting resin, a wax, or the like to be formed into a pellet, a powder, or a paste form, and used as a reversible thermochromic molding resin composition.

[0425] The above-mentioned reversible thermochromic molding resin composition is obtained by general injection molding, extrusion molding, blow molding, or casting molding to obtain a molded body in the form of a three-dimensional shape, film, sheet, plate, filament, rod, tube, etc. of any shape.

[0426] Furthermore, by melt-blending with a thermoplastic resin, a toner or a powder coating can be obtained.

[0427] Furthermore, by mixing a non-thermochromic colorant such as a common dye or pigment into the above-mentioned reversibly thermochromic liquid composition, coating solid molded article, or molding resin composition, a color change behavior from color (1) to color (2) can be exhibited.

[0428] By laminating a layer containing a light stabilizer and / or a transparent metallic pigment on the above-mentioned molded body or laminate, the light resistance can be improved, or by providing a top coat layer, the durability can be improved.

[0429] Examples of the light stabilizer include ultraviolet absorbers, antioxidants, singlet oxygen quenchers, superoxide anion quenchers, and ozone quenchers.

[0430] Examples of the transparent metallic luster pigment include pigments obtained by coating the surface of natural mica, synthetic mica, glass flakes, aluminum oxide, or transparent film flakes as a core material with a metal oxide such as titanium oxide.

[0431] Specific examples of products using a reversible thermochromic composition and microcapsule pigments or resin particles encapsulating the reversible thermochromic composition include the following.

[0432] (1) Toys

[0433] Dolls and animal figure toys, hair for dolls and animal figure toys, doll houses and furniture, clothes, hats, handbags, shoes and other doll accessories, decorative toys, stuffed dolls, painting toys, toy picture books, puzzles and other educational toys, building block toys, block toys, clay toys, mobile toys, spinning tops, kites, musical instrument toys, cooking toys, gun toys, capture toys, background toys, toys imitating vehicles, animals, plants, buildings, food, etc., etc.

[0434] (2) Clothing

[0435] Clothing such as T-shirts, training suits, women's shirts, women's dresses, swimsuits, raincoats, ski suits, shoes and shoelaces, handkerchiefs, towels, cloth bags and other cloth belongings, gloves, ties, hats, bow ties, scarves, etc.

[0436] (3)Indoor decorations

[0437] Curtains, curtain cords, tablecloths, floor coverings, cushions, carpets, travel rugs, chair covers, seats, cushions, decorative frames, artificial flowers, photo frames, etc.

[0438] (4) Furniture

[0439] Bedding, pillows, mattresses and other bedding, lighting fixtures, air conditioners, etc.

[0440] (5) Decorations

[0441] Rings, bracelets, headdresses, earrings, hairpins, false nails, ribbons, bow ties, watches, glasses, etc.

[0442] (6) Stationery

[0443] Writing tools, stamp tools, erasers, pads, rulers, notebooks, adhesive tapes, etc.

[0444] (7) Daily necessities

[0445] Lipstick, eye shadow, foundation, eyeliner, eyebrow pencil, nail polish, hair dye, false nails, false nail paint and other cosmetics, toothbrushes, etc.

[0446] (8) Kitchen supplies

[0447] Cups, plates, chopsticks, spoons, forks, pots, pans, etc.

[0448] (9) Others

[0449] Calendars, labels, cards, recording materials, various printed materials for anti-counterfeiting, books such as picture albums, handbags, packaging containers, embroidery threads, sports equipment, fishing gear, coasters, musical instruments, pocket warmers, coolants, bags such as wallets, umbrellas, vehicles, buildings, temperature detection indicators, teaching aids, etc.

[0450] Example

[0451] Examples are shown below. In addition, unless otherwise specified, "parts" and "%" in the examples represent "parts by mass" and "mass %", respectively.

[0452] <Example 101>

[0453] Preparation of reversible thermochromic microcapsule pigments

[0454] 6.5 parts of 2-(3-trifluoromethylanilino)-6-di-n-pentylaminofluoran (A-1) as component (a), 4 parts of 4,4'-[1-{4-〔1-(4-hydroxyphenyl)-1-methylethyl〕phenyl}ethylene]bisphenol (I-1) as component (b), 6 parts of 1,1-bis(4-hydroxyphenyl)-2-ethylhexane (IIa-1), 25 parts of behenyl alcohol (C-1) as component (c), and 25 parts of stearyl stearate (C-2) were mixed and dissolved under heating to obtain a reversible thermochromic composition that undergoes a reversible color change. The reversible thermochromic composition was added to a mixed solution consisting of 35 parts of an aromatic isocyanate prepolymer and 40 parts of a cosolvent as a wall material, emulsified and dispersed in an 8% polyvinyl alcohol aqueous solution, and stirred while heating. Then, 2.5 parts of a water-soluble aliphatic modified amine was added, and stirring was continued to prepare a microcapsule dispersion. A microcapsule pigment with an average particle size of 2.0 μm was obtained from the microcapsule dispersion by centrifugal separation.

[0455] <Examples 102 to 106, 201 to 209 and Comparative Examples 101, 102, 201 to 209>

[0456] A microcapsule pigment was obtained in the same manner as in Example 101 except that the types and addition amounts of the components (a), (b) and (c) were changed to those shown in Table 1 or Table 2.

[0457] The color tone of the obtained microcapsule pigment in the color development state is as shown in Tables 1 and 2, and changes from the color development state to the decolorization state.

[0458] The numerical values ​​of the components (a), (b), and (c) in the table represent "parts by mass", and the numerical values ​​of the concentration retention rates represent "%".

[0459] [Table 1]

[0460]

[0461] [Table 2]

[0462] Table 2

[0463]

[0464] The components (a), (b), and (c) in the table are the compounds shown below.

[0465] A-1 2-(3-trifluoromethylanilino)-6-di-n-pentylaminofluoran

[0466] A-2 6-(N-ethyl-N-isopentylamino)-1,2-benzofluoran

[0467] A-3 2-Di-n-butylamino-8-di-n-pentylamino-4-methylspiro[5H-[1]benzopyrano[2,3-d]pyrimidine-5,1'(3'H)-isobenzofuran]-3'-one

[0468] A-4 1,3-Dimethyl-6-diethylaminofluoran

[0469] A-5 2-N-methylanilino-6-(N-ethyl-N-p-tolylamino)fluoran

[0470] A-6 3,3-Bis(2-ethoxy-4-diethylaminophenyl)-4-azaphthalide

[0471] A-7 3,3-bis(4-dimethylaminophenyl)-6-dimethylaminophthalide

[0472] A-8 3,6-bis(diphenylamino)fluoran

[0473] A-9 3-(2-acetamido-4-diethylaminophenyl)-3-(1-propyl-2-methylindol-3-yl)-4-azaphthalide

[0474] I-1 4,4'-[1-{4-〔1-(4-hydroxyphenyl)-1-methylethyl〕phenyl}ethylidene]bisphenol

[0475] I-2 4,4',4"-Ethylenetriphenol

[0476] I-3 1-phenyl-1,1-bis(4-hydroxyphenyl)ethane

[0477] I-4 4,4'-〔4-(4-hydroxyphenyl)-sec-butylene〕bis(2-methylphenol)

[0478] IIa-1 1,1-Bis(4-hydroxyphenyl)-2-ethylhexane

[0479] IIa-2 2,2-Bis(4-hydroxyphenyl)propane

[0480] IIa-3 1,1-Bis(4-hydroxyphenyl)-2-methylpropane

[0481] IIa-4 2,2-Bis(4-hydroxyphenyl)hexafluoropropane

[0482] IIb-1 2,4-Dihydroxy-4'-tert-butylbenzophenone

[0483] C-1 Behenyl Alcohol

[0484] C-2 Stearyl Stearate

[0485] C-3 4-Benzyloxyphenyl ethyl decanoate

[0486] C-4 4-Biphenylacetic acid cyclohexyl methyl ester

[0487] [Color change temperature measurement]

[0488] 40 parts of each microcapsule pigment obtained in Examples 101 to 106, 201 to 209 and Comparative Examples 101, 102, 201 to 209, 52 parts of ethylene-vinyl acetate copolymer resin emulsion, 5 parts of thickener, and 3 parts of leveling agent were mixed to prepare a reversible thermochromic ink. A full-screen pattern was screen-printed on high-quality paper using the above ink to obtain a sample for measuring color change temperature. The above samples for measuring color change temperature were placed in the measuring part of a colorimeter [Tokyo Denshoku Co., Ltd., product name: TC-3600], and the sample part was heated and cooled at a rate of 2°C / min. The lightness value was measured as the color density at each temperature, and a color density-temperature curve was prepared. From the color density-temperature curve, the complete color development temperature t1, the color development start temperature t2, the decolorization start temperature t3, the complete decolorization temperature t4, and ΔH [hysteresis width: (the temperature between t3 and t4)-(the temperature between t1 and t2)] were obtained. The obtained results are shown in Tables 3 and 4 below.

[0489] The values ​​in the table indicate "℃".

[0490] [Table 3]

[0491] Table 3

[0492]

[0493] [Table 4]

[0494] Table 4

[0495]

[0496] [Concentration measurement]

[0497] A reversible thermochromic ink was prepared by mixing 40 parts of each microcapsule pigment obtained in Examples 101 to 106, 201 to 209 and Comparative Examples 101, 102, 201 to 209, 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 high-quality paper using the ink to obtain a sample for concentration measurement.

[0498] The concentration measurement samples of Examples 101 to 106, 201 to 209 and Comparative Examples 101, 102, 201 to 209, which were cooled to below t1 and thus in a completely colored state, were placed in the measuring part of a fluorescence spectrophotometer [manufactured by Conika Minolta Co., Ltd., product name: FD-7 model], and the absolute concentration in the colored state (hereinafter referred to as “coloring concentration”) was measured.

[0499] In addition, the concentration measurement samples of Examples 101 to 106, 201 to 209 and Comparative Examples 101, 102, 201 to 209, which were heated to a completely decolorized state at a temperature of t4 or higher, were placed in the measurement portion of the fluorescence spectrophotometer, and the absolute concentration in the decolorized state (hereinafter referred to as "decolorized concentration") was measured. The results obtained are shown in Tables 1 and 2.

[0500] [Light resistance evaluation]

[0501] Reversible thermochromic ink was prepared by mixing 40 parts of each microcapsule pigment of Examples 101 to 106, 201 to 209 and Comparative Examples 101, 102, 201 to 209, 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 high-quality paper using the ink to obtain a measurement sample.

[0502] After the above-mentioned measurement samples were cooled to below t1 and became a completely colored state, they were placed in the measurement part of a fluorescence spectrophotometer [manufactured by Conika Minolta Co., Ltd., product name: FD-7 model] and the absolute concentration in the completely colored state (hereinafter referred to as "initial concentration") was measured.

[0503] Next, each sample having its concentration measured was subjected to a xenon light fastness tester (manufactured by Suga Testing Instrument Co., Ltd., product name: テーブルサン XT75) at 170 w / m 2 The irradiance was continuously irradiated for 10 hours.

[0504] After taking out each measurement sample after light irradiation and cooling to below t1 to become a completely colored state, each measurement sample was placed in the measurement part of the above-mentioned fluorescence spectrophotometer to measure the absolute concentration of the completely colored state after light irradiation (hereinafter referred to as "concentration after light irradiation").

[0505] The concentration retention rate was calculated from the initial concentration value and the concentration value after light irradiation [(value of concentration after light irradiation) / (value of initial concentration) × 100]. In addition, the larger the value of the concentration retention rate, the better the light resistance. The results are shown in Tables 1 and 2.

[0506] Application Example 1

[0507] Production of reversible thermochromic writing tool (reversible thermochromic ballpoint pen)

[0508] 25 parts of the microcapsule pigment of Example 102 (pre-cooled to below -20°C to make it black), 0.3 parts of a shear viscosity-reducing agent (xanthan gum), 10 parts of urea, 10 parts of glycerol, 0.5 parts of a nonionic permeability-imparting agent [manufactured by Sannopuco Co., Ltd., product name: Nopco SW-WET-366], and 0.5 parts of a modified silicone defoaming agent [manufactured by Sannopuco Co., Ltd., product name: Nopco SW-WET-366] were added. The invention also discloses a method for preparing a reversible thermochromic liquid composition as an ink for writing instruments by mixing 0.1 parts of PUCO 8034, 0.5 parts of a phosphate surfactant (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., product name: PLISAF AL), 0.5 parts of a pH adjuster (triethanolamine), 0.2 parts of a mildew preventive (manufactured by Lonza Japan Co., Ltd., product name: Proccell XL-2), and 52.9 parts of water.

[0509] After the ink for the writing tool is sucked and filled into an ink receiving tube made of a polypropylene tube, it is connected to a ballpoint pen tip having a superhard ball with a diameter of 0.5 mm at the front end through a resin holder. Next, a viscoelastic ink backflow prevention body (liquid plug) with polybutene as the main component is filled from the rear end of the ink receiving tube to produce a ballpoint pen refill. The refill is incorporated into the barrel to obtain a ballpoint pen (retractable ballpoint pen).

[0510] The ballpoint pen has a structure in which the pen tip provided in the ballpoint pen refill is stored in the barrel in a state of being exposed to the outside air, and the pen tip protrudes from the front end opening of the barrel by the operation of a retractable mechanism (sliding mechanism) in the shape of a pen clip provided on the rear side wall of the barrel. In addition, SEBS resin is installed as a friction member at the rear end of the barrel.

[0511] When the ballpoint pen is used to write on the paper, black characters (handwriting) are formed. The handwriting appears black at room temperature (25°C). If the characters are rubbed with a friction member, the characters fade and become colorless. This state can be maintained as long as it is not cooled below -20°C. In addition, if the paper is placed in a freezer and cooled below -20°C, the characters change color again, and this color change behavior can be reproduced repeatedly.

[0512] Application Example 2

[0513] Preparation of reversible thermochromic recording material (card for information display)

[0514] 40 parts of the microcapsule pigment of Example 105 (pre-cooled to below -20°C to make it black in color) are uniformly mixed in an aqueous color carrier composed of 50 parts of a urethane resin emulsion, 3 parts of a leveling agent, and 1 part of a thickener to prepare a reversible thermochromic liquid composition for printing ink.

[0515] On the surface of a transparent polyester film (thickness 25 μm) with an adhesive layer set on the back as a support, a transparent adhesion coating formed by a carbamate resin and an isocyanate curing agent is set, and the above-mentioned printing ink is used on the upper layer to implement full-screen printing using a screen, and is dried to solidify it, and a reversible thermochromic layer is set. Further, a transparent protective layer containing epoxy acrylate oligomers, polyester acrylate oligomers, and acrylate monomers is set on the upper layer and irradiated with ultraviolet rays to polymerize it to produce a reversible thermochromic recording material. Then, the above-mentioned recording material is pasted on a white polyester film (thickness 188 μm) as a substrate and provided for practical use as a card for information display.

[0516] The reversible thermochromic recording material was temporarily cooled to below -20°C to completely color the reversible thermochromic layer black, and then text information was printed using a thermal printer with a thermal head.

[0517] The recording material clearly displays white text information (hollow text) on a black background, and the white text information can be recognized as long as it is kept in a temperature range of more than -20°C and less than 58°C. In addition, if the recording material is cooled to below -20°C and the reversible thermochromic layer is completely colored black, the white hollow text cannot be recognized. From this state, the thermal printer can be used again to form white hollow text on the reversible thermochromic layer, and the recording material can be used repeatedly.

[0518] Application Example 3

[0519] Production of reversible thermochromic printed materials

[0520] Mix 30 parts of the microcapsule pigment of Example 106 (pre-cooled to below -20°C to make it black), 5 parts of red dye, and 65 parts of linseed oil-based offset ink vehicle to prepare a reversible thermochromic liquid composition for offset printing ink.

[0521] The offset printing is performed on both sides of the high-quality paper as the printing medium using the above-mentioned offset printing ink, and the date (thermochromic image) is formed by drying and solidifying. It should be noted that the thermochromic images on the front and back sides do not overlap. Next, offset printing is performed using non-color-changing black offset printing ink, and the frame line (non-color-changing image) is formed by drying and solidifying, thereby producing a reversible thermochromic printed matter.

[0522] The reversible thermochromic printed material is initially a printed material in the form of a notebook with a date formed in black, but can be changed to red by friction heat generated by rubbing the thermochromic image at any position on the surface with a friction member, and the changed state can be maintained at room temperature (25°C), so it is useful for schedule management on weekends. In addition, the date set on the back of the changed position does not change color due to heat transfer when the thermochromic image on the surface changes color, so accurate schedule management can be performed.

[0523] Application Example 4

[0524] Production of doll toys with hair using reversible thermochromic composite fibers

[0525] 5 parts of the microcapsule pigment of Example 201, 1 part of dispersant, 94 parts of nylon 12 with a melting point of 180°C, and 0.1 parts of a general blue pigment are melt-mixed at 200°C using an extruder to prepare a reversible thermochromic molding resin composition in particle form for the core.

[0526] The above-mentioned particles are supplied to an extruder for core molding, and nylon 12 natural particles are supplied to an extruder for sheath molding. The fibers are spun from an 18-hole discharge hole at 200°C using a composite fiber spinning device in a manner such that the volume ratio of the core:sheath becomes 6:4, thereby preparing a reversible thermochromic composite fiber consisting of 18 single filaments with an outer diameter of 90 μm.

[0527] If the reversible thermochromic composite fiber is temporarily cooled to below -20°C to allow the microcapsule pigment to fully develop color, the reversible thermochromic composite fiber will show a purple color mixed with the red color produced by the microcapsule pigment and the blue color produced by the general pigment. The reversible thermochromic composite fiber is implanted on the head of a doll by a conventional method to produce a doll toy with hair using the reversible thermochromic composite fiber.

[0528] The hair of the doll does not change at body temperature or ambient temperature, but changes from purple to blue when heated to 59°C or higher. Furthermore, it changes to purple again when cooled to -20°C or lower. This change can be repeated.

[0529] In addition, the color of the hair can be changed arbitrarily by heating a part of the hair with a dryer or the like to remove the color and forming a pattern in which only an arbitrary position is removed the color. In addition, the color change state can be maintained at room temperature (25°C), and the hair can be heated to 59°C or higher to remove the color and then cooled to -20°C or lower to recolor to purple.

[0530] Application Example 5

[0531] Production of reversible thermochromic writing tool (reversible thermochromic marker)

[0532] 20 parts of the microcapsule pigment of Example 202 (pre-cooled to -20°C or below so that its color develops to pink) were mixed with 0.4 parts of a polymer flocculant (hydroxyethyl cellulose) [manufactured by Dawuchemikar Japan Co., Ltd., product name: CELLOSIZE EP-09], 0.4 parts of an acrylic polymer dispersant [manufactured by Nippon Lubrizol Co., Ltd., product name: Solspas 43000], 0.2 parts of a preservative (sodium 2-pyridinethiol 1-oxide) [manufactured by Lonzajap Co., Ltd., product name: Sodium Amino Magnet], and 0.2 parts of a preservative (3-iodo-2-propynyl N-butylcarbamate) [manufactured by Lonzajap Co., Ltd., product name: Sodium Amino Magnet]. A reversible thermochromic liquid composition as an ink for writing instruments is prepared by mixing 0.2 parts of Gluconol (manufactured by Sometu Co., Ltd., product name: Gluconol 2000), 18 parts of glycerin, 0.2 parts of a defoaming agent, 1 part of a pH adjuster (10% diluted phosphoric acid solution), 8 parts of a specific gravity adjuster (sodium polytungstate) (manufactured by Sometu Co., Ltd., product name: SPT), and 46.6 parts of water in an aqueous vehicle.

[0533] The ink for writing tools is impregnated in an ink absorbing body obtained by coating a polyester strip with a synthetic resin film, and then contained in a barrel formed of polypropylene resin. A resin-processed pen body (shell-shaped) composed of an extruded body of polyacetal resin having a plurality of ink outlet holes extending in the axial direction is assembled in a connected state at the front end of the barrel via a retainer, and a cap is installed to produce a marker pen. SEBS resin is installed as a friction member on the top of the cap.

[0534] The above-mentioned marker pen is used to write on the paper to form pink text (handwriting). As a result, the handwriting appears pink at room temperature (25°C). If the text is rubbed with a friction member, the text fades and becomes colorless. This state can be maintained as long as it is not cooled below -20°C. In addition, if the paper is placed in a freezer and cooled to below -20°C, the text changes color again and becomes pink. This color change behavior can be reproduced repeatedly.

[0535] Application Example 6

[0536] Production of reversible thermochromic writing tool (reversible thermochromic marker)

[0537] 23 parts of the microcapsule pigment of Example 203 (pre-cooled to -20°C or less so that it develops an orange color) were mixed with 0.4 parts of a polymer flocculant (hydroxyethyl cellulose) [manufactured by Dawuchemikar Japan Co., Ltd., product name: CELLOSIZE WP-09], 0.4 parts of an acrylic polymer dispersant [manufactured by Lubrizol Japan Co., Ltd., product name: Solspas 43000], 0.2 parts of a preservative (sodium 2-pyridinethiol 1-oxide) [manufactured by Lonzapan Co., Ltd., product name: Sodium 2-pyridinethiol 1-oxide], 0.2 parts of a preservative (3-iodo-2-propynyl N-butyl A reversible thermochromic liquid composition as an ink for writing instruments was prepared by mixing 0.2 parts of 1,2-diaminobenzene (aminocarbamate) [manufactured by Ronza Japan Co., Ltd., product name: Graic Acid 2000], 30 parts of glycerin, 0.01 parts of a defoaming agent, 0.03 parts of a pH adjuster (10% diluted phosphoric acid solution), and 45.76 parts of water into an aqueous vehicle.

[0538] The ink for writing tools is impregnated in an ink absorbing body obtained by coating a polyester strip with a synthetic resin film, and then contained in a barrel formed of polypropylene resin. A resin-processed pen body (wedge-shaped) of polyester fiber is assembled in a connected state at the front end of the barrel through a resin holder, and a cap is installed to produce a marker pen. In addition, SEBS resin is installed as a friction member at the rear end of the barrel.

[0539] The above-mentioned marker pen is used to write on the paper to form orange text (handwriting). As a result, the handwriting appears orange at room temperature (25°C). If the text is rubbed with a friction member, the text fades and becomes colorless. This state can be maintained as long as it is not cooled below -20°C. In addition, if the paper is placed in a freezer and cooled to below -20°C, the text changes color again and becomes orange. This color change behavior can be reproduced repeatedly.

[0540] Application Example 7

[0541] Preparation of reversible thermochromic solid writing instruments

[0542] 40 parts of the microcapsule pigment of Example 204, 35 parts of filler (talc), 10 parts of excipient (side chain crystalline polyolefin) [manufactured by Toyokuni Oil Co., Ltd., product name: HS Crystal 4100], 10 parts of excipient (polyolefin wax) [manufactured by Sanyo Chemical Industries, Ltd., product name: Sunworks 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-based light stabilizer were kneaded with a kneader to prepare a kneaded material 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 with a kneader to prepare a kneaded material for the outer shell. The kneaded material for the outer shell is wound around the outer circumference of the inner core so as to form the inner core, and is compressed and molded by a pressing machine to form an outer diameter of The length is 60mm (the inner core is φ2mm, and the outer shell coating thickness is 0.5mm), thereby producing a solid writing body with a core-sheath structure. In addition, the above dimensions are set values. After compression molding, it is cooled to -20°C and returned to room temperature to produce a solid writing body.

[0543] A pencil is obtained by housing and molding the above-mentioned solid writing body in a circular outer shaft (wooden shaft). Furthermore, at the rear end of the pencil, a cylindrical friction body formed of SEBS resin is adhered via a metal connecting member to produce a solid writing tool with a friction body (a pencil with a friction body). The above-mentioned solid writing tool is used to write on a paper to form green text (handwriting). As a result, the handwriting appears green at room temperature (25°C). If the text is rubbed with a friction member, the text fades and becomes colorless. This state can be maintained as long as it is not cooled below -20°C. In addition, if the paper surface is placed in a freezer and cooled below -20°C, the text will change color again and the color change behavior will turn green, and this color change behavior can be reproduced repeatedly.

[0544] Application Example 8

[0545] Production of reversible thermochromic writing tool (reversible thermochromic ballpoint pen)

[0546] 25 parts of the microcapsule pigment of Example 206 (pre-cooled to below -20°C to make it blue), 0.3 parts of a shear viscosity-reducing agent (xanthan gum), 10 parts of urea, 10 parts of glycerol, 0.5 parts of a nonionic permeability-imparting agent [manufactured by Sannopuco Co., Ltd., product name: Nopco SW-WET-366], and 0.5 parts of a modified silicone defoaming agent [manufactured by Sannopuco Co., Ltd., product name: Nopco SW-WET-366] were added. The invention also discloses a method for preparing a reversible thermochromic liquid composition as an ink for writing instruments by mixing 0.1 parts of PUCO 8034, 0.5 parts of a phosphate surfactant (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., product name: PLISAF AL), 0.5 parts of a pH adjuster (triethanolamine), 0.2 parts of a mildew preventive (manufactured by Lonza Japan Co., Ltd., product name: Proccell XL-2), and 52.9 parts of water.

[0547] After the ink for writing tools is sucked and filled into an ink receiving tube composed of a polypropylene tube, it is connected to the tip of a ballpoint pen holding a stainless steel ball with a diameter of 0.5 mm at the front end via a resin holder. Next, a viscoelastic ink backflow prevention body (liquid plug) with polybutene as the main component is filled from the rear end of the ink receiving tube, and the tail plug is further engaged with the rear part of the tube, and the front shaft cylinder and the rear shaft cylinder are assembled. After the cover is put on, degassing is carried out by centrifugal separation to produce a ballpoint pen. In addition, SEBS resin as a friction member is installed at the rear end of the rear shaft cylinder.

[0548] The above ballpoint pen is used to write on the paper to form blue text (handwriting). As a result, the handwriting appears blue at room temperature (25°C). If the text is rubbed with a friction member, the text fades and becomes colorless. This state can be maintained as long as it is not cooled below -20°C. In addition, if the paper is placed in a freezer and cooled to below -20°C, the text changes color again and becomes blue. This color change behavior can be reproduced repeatedly.

[0549] Application Example 9

[0550] Production of reversible thermochromic stamp

[0551] Mix 20 parts of the microcapsule pigment of Example 207 (pre-cooled to below -20°C to make it blue in color), 50 parts of glycerin, 1.5 parts of an alkali-soluble acrylic emulsion [manufactured by LAM AND HAS DIAPAN CO., LTD., product name: Primer DR73], 0.9 parts of triethanolamine, 10 parts of a 50% aqueous solution of polyvinyl pyrrolidone, 0.2 parts of a silicone defoaming agent, 0.5 parts of a penetrating leveling agent, 0.2 parts of a preservative, and 16.7 parts of water to prepare a reversible thermochromic liquid composition for use as a stamp ink.

[0552] The above-mentioned seal is impregnated with ink in a seal material with continuous pores, adhered to a seal base material in a manner that the seal face of the seal material is exposed, and a cover is put on to produce a seal. In addition, a SEBS resin as a friction member is installed at the rear end of the seal base material.

[0553] If the stamp is repeatedly pressed against the surface to be stamped (paper surface), the ink will flow out smoothly from the stamp surface of the stamp material and transfer to the stamp surface, and the imprint will not bleed, and a clear imprint can be continuously formed. The imprint appears blue at room temperature (25°C). If it is rubbed with a friction member, the imprint will fade and become colorless. This state can be maintained as long as it is not cooled below -20°C. In addition, if the paper surface is placed in a freezer and cooled below -20°C, the imprint will change color again and turn blue, and this color change behavior can be reproduced repeatedly.

[0554] Application Example 10

[0555] Production of reversible thermochromic printed materials (reversible thermochromic T-shirts)

[0556] 30 parts of the microcapsule pigment of Example 208 (pre-cooled to below -20°C to make it red in color) are uniformly mixed in an aqueous color carrier composed of 60 parts of an acrylic emulsion (45% solid content), 0.2 parts of a defoaming agent, 1 part of a viscosity regulator, and 8.8 parts of water to prepare a reversible thermochromic liquid composition for printing ink.

[0557] On a white T-shirt (made of cotton) as a support, a plurality of heart patterns were printed using the printing ink using a 100-mesh screen, and the printing ink was dried and solidified to form a reversible thermochromic layer, thereby producing a reversible thermochromic printed product (reversible thermochromic T-shirt).

[0558] At room temperature (25°C), multiple red heart patterns can be recognized on the surface of the T-shirt. This does not change at body temperature or ambient temperature. However, if the T-shirt is heated to 58°C or higher, the portion with the heart pattern printed on it becomes colorless and the red heart pattern cannot be recognized. Furthermore, if the T-shirt is cooled to -20°C or lower, the red heart pattern can be recognized again. This change can be repeated.

[0559] In addition, a portion of the heart pattern on the surface of the T-shirt can be decolorized by heating with an iron or the like, thereby forming a pattern in which only an arbitrary heart pattern is decolorized, and the pattern of the T-shirt can be arbitrarily changed. In addition, the color change state can be maintained at room temperature (25°C), and the heart pattern portion can be decolorized by heating the entire T-shirt to 58°C or more, and then cooled to -20°C or less to make the heart pattern recolor.

[0560] Application Example 11

[0561] Fabrication of reversible thermochromic plug

[0562] 2.5 parts of the microcapsule pigment of Example 209 (pre-cooled to below -20°C to make it blue-green in color) and 1.5 parts of a general orange pigment are stirred and mixed in an oily vehicle composed of 12.5 parts of vinyl chloride-vinyl acetate copolymer, 38.3 parts of xylene, 45 parts of butyl acetate, and 0.2 parts of a viscosity modifier to prepare a reversible thermochromic liquid composition for use as a coating for spray coating.

[0563] The above-mentioned coating material was spray-coated on a plug portion (white) of a household electric wire as a support, and dried to provide a reversible thermochromic layer, thereby producing a reversible thermochromic plug.

[0564] If a reversible thermochromic plug appears brown at room temperature (25°C) and changes to orange at a temperature of 59°C or above, the orange color change state can be maintained as long as it is not cooled below -20°C. Therefore, the temperature history of the plug when it becomes overheated and reaches a high temperature range of 59°C or above can be visually confirmed.

[0565] Explanation of symbols

[0566] t1 complete color temperature

[0567] T2 color starting temperature

[0568] t3 color fading starting temperature

[0569] T4 complete decolorization temperature

[0570] T1 Complete decolorization temperature

[0571] T2 color fading starting temperature

[0572] T3 color starting temperature

[0573] T4 full color temperature

[0574] ΔH is the hysteresis width.

Claims

1. A reversible thermochromic composition comprising: (a) an electron-donating color-developing organic compound; (b) a combination of a compound represented by formula (I) and a compound represented by formula (IIa) as electron-accepting compounds; and (c) a reaction medium that causes the electron transfer reaction between components (a) and (b) to occur reversibly in a specific temperature range, wherein the reaction medium is selected from: aliphatic monohydric saturated alcohols having 10 or more carbon atoms; esters obtained by combining aliphatic monocarboxylic acids and aliphatic monohydric alcohols; a compound represented by formula (2); and a compound represented by formula (7), In formula (I), R 11 is a hydrogen atom or a methyl group, L is a single bond or ethylene, R 14 is methyl, ethyl, cyclohexyl, methoxy, ethoxy, hydroxyphenyl substituted propyl or hydroxyl, n12 and n13 are 0, n14 is 0 or 1, In formula (I), the hydroxyl groups are located at the 4 positions of the benzene ring. In formula (IIa), R a1 and R a2 Each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 17 carbon atoms, wherein: The methylene group, i.e., the -CH2- group, in the alkyl group may be replaced by an oxy group, i.e., the -O- group, or a carbonyl group, i.e., the -CO- group, and R a1 and R a2 At least one of them is a linear or branched alkyl group having 5 to 9 carbon atoms, na3 and na4 are 0, In formula (IIa), the hydroxyl group is located at the 4-position of the benzene ring. In formula (2), R represents an alkyl group or alkenyl group having 8 or more carbon atoms, In formula (7), 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.

2. The composition according to claim 1, wherein in formula (I), L is a single bond, R 14 The hydroxyphenyl group is substituted with a propyl group or a hydroxy group.

3. The composition according to claim 1, wherein in formula (IIa), R a1 and R a2 One of them is a branched alkyl group having 5 to 9 carbon atoms, and the other is a hydrogen atom or a methyl group.

4. The composition according to claim 1, wherein in formula (I), L is a single bond, n14 is 0, and In formula (IIa), R a1 and R a2 One of them is a branched alkyl group having 5 to 9 carbon atoms, and the other is a hydrogen atom or a methyl group. 5 . The composition according to claim 1 , wherein the mass ratio of the compound represented by formula (I) to the compound represented by formula (IIa) is 1:0.5 to 1:

5.

6. A reversible thermochromic microcapsule pigment, containing the composition according to any one of claims 1 to 5.

7. A reversible thermochromic liquid composition comprising the reversible thermochromic microcapsule pigment according to claim 6 and a vehicle.

8. The reversible thermochromic liquid composition according to claim 7, which is selected from printing ink, writing ink, coating ink, stamp ink, inkjet ink, coating material, ultraviolet curable ink, painting pigment, cosmetic, and fiber coloring liquid.

9. A solid writing material or solid cosmetic, comprising the reversible thermochromic microcapsule pigment according to claim 6 and an excipient. 10 . A reversible thermochromic molding resin composition comprising the reversible thermochromic microcapsule pigment according to claim 6 and a molding resin. 11 . A reversibly thermochromic molded article, which is obtained by molding the reversibly thermochromic molding resin composition according to claim 10 . 12 . A reversible thermochromic laminate comprising a support and a reversible thermochromic layer comprising the reversible thermochromic microcapsule pigment according to claim 6 .

13. A writing implement containing the reversible thermochromic liquid composition according to claim 7.

14. The writing instrument according to claim 13, comprising a friction member that changes the color of handwriting obtained by the writing instrument by frictional heat.

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