Reversible thermochromic composition and reversible thermochromic microcapsule pigments containing the same

Abstract

The present invention provides a reversible thermochromic composition which exhibits black color upon coloration and colorless color upon discoloration, and has excellent light resistance, by using a fluoran derivative having a specific structure as an electron-donating chromogenic organic compound, and a reversible thermochromic microcapsule pigment containing the reversible thermochromic composition. The means for solving the problem is a reversible thermochromic composition comprising: (a) a fluoran derivative having a specific structure as an electron-donating chromogenic organic compound, (b) a compound having a specific structure as an electron-accepting compound, and (c) a reaction medium which allows the electron transfer reaction between the (a) component and the (b) component to occur reversibly in a specific temperature range, and a reversible thermochromic microcapsule pigment containing the reversible thermochromic composition.

Description

Reversible thermochromic composition and reversible thermochromic microcapsule pigment containing the reversible thermochromic composition Technical Field

[0001] This invention relates to reversible thermochromic compositions and reversible thermochromic microcapsule pigments encapsulating the reversible thermochromic compositions. More specifically, it relates to reversible thermochromic compositions that exhibit black color when they develop color and change to colorless color when they decolorize, and reversible thermochromic microcapsule pigments encapsulating the reversible thermochromic compositions. Background Technology

[0002] Conventional methods have disclosed reversible thermochromic compositions that change color from black to green to colorless, requiring an electron-donating chromogenic organic compound, an electron-accepting compound, and a reaction medium that allows the electron transfer reaction of the electron-donating chromogenic organic compound and the electron-accepting compound to occur reversibly within a specific temperature range. For example, Patent Document 1 discloses a thermochromic composition containing a specific electron-donating chromogenic organic compound (colorless pigment).

[0003] If these compositions are exposed to light during color development, the color intensity may decrease over time. Therefore, it is required that the decrease in color intensity be suppressed even when exposed to light, i.e., excellent lightfastness.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2017-101193 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] The present invention is based on the background technology described above, and aims to provide a reversible thermochromic composition that exhibits black color when it is activated and changes to colorless when it is decolorized, and has excellent lightfastness, as well as a reversible thermochromic microcapsule pigment containing the reversible thermochromic composition.

[0009] Methods for solving problems

[0010] The reversible thermochromic composition of the present invention comprises:

[0011] (a) The compound represented by formula (A) as an electron-donating chromogenic organic compound;

[0012] (b) compounds of formula (B1), (B2), (B3), (B4) or (B5) that are electron-accepting compounds; and

[0013] (c) A reaction medium that allows the electron transfer reactions of components (a) and (b) to occur reversibly in a specific temperature range.

[0014]

[0015] (in the formula,

[0016] R a1 It is methyl or ethyl.

[0017] R a2 It is methyl.

[0018] p is 1 or 2, where R a1 and all R a2 The total number of carbon atoms is 2 or 3.

[0019] R a3 It is a halogen atom, a straight-chain or branched alkyl group having 1 to 4 carbon atoms, or a straight-chain or branched alkoxy group having 1 to 3 carbon atoms.

[0020] q is 0 or 1)

[0021]

[0022] (in the formula,

[0023] R b1 It consists of hydrogen atoms, a straight-chain or branched alkyl group having 1 to 17 carbon atoms, or an aryl group having 6 to 10 carbon atoms.

[0024] R b2 It is a straight-chain or branched alkyl group having 1 to 17 carbon atoms (wherein the methylene (-CH2-) group in the above alkyl group can be replaced by an oxy (-O-) group, a carbonyl (-CO-) group, or an imino (-NH-) group), or an aryl group having 6 to 10 carbon atoms.

[0025] Among them, R b1 With R b2 They can form a ring together.

[0026] R b3 and R b4 Each can be independently a straight-chain or branched alkyl group with 1 to 4 carbon atoms, an alkenyl group with 2 to 4 carbon atoms, an aryl group with 6 to 10 carbon atoms, or a halogen atom that can be substituted by a fluorine atom or a hydroxyl group.

[0027] Among them, all R b1 ~R b4 The total number of carbon atoms is 3 or more.

[0028] n3 and n4 are each independently 0 to 2.

[0029]

[0030] (in the formula,

[0031] R b5 It consists of hydrogen atoms or straight-chain or branched alkyl groups having 1 to 6 carbon atoms.

[0032] L is a single bond, a straight-chain or branched alkylene group with 1 to 3 carbon atoms, an aryl-substituted alkylene group with 7 to 9 carbon atoms, or an arylene group with 6 to 10 carbon atoms.

[0033] R b6 R b7 and R b8 Each of the following can be independently substituted by a fluorine atom: a straight-chain or branched alkyl group having 1 to 4 carbon atoms; 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.

[0034] n6, n7, and n8 are each independently 0 to 3.

[0035]

[0036] (in the formula,

[0037] R b9 It is a straight-chain or branched alkyl group with 1 to 4 carbon atoms that has been replaced by fluorine atoms.

[0038] R b10 It is a straight-chain or branched alkyl group with 1 to 4 carbon atoms that can be replaced by fluorine atoms, or an aryl group with 6 to 10 carbon atoms.

[0039] Among them, R b9 With R b10 They can form a ring together.

[0040] R b11 and R b12 Each can be independently a straight-chain or branched alkyl group with 1 to 4 carbon atoms, an alkenyl group with 2 to 4 carbon atoms, an aryl group with 6 to 10 carbon atoms, or a halogen atom that can be substituted by a fluorine atom or a hydroxyl group.

[0041] n11 and n12 are each independently 0 to 2.

[0042]

[0043] (in the formula,

[0044] Rb13 It is a hydrogen atom, a straight-chain or branched alkyl group having 1 to 4 carbon atoms, an alkenyl group having 2 to 4 carbon atoms, an aryl group having 6 to 10 carbon atoms, or an aryl-substituted alkyl group having 7 to 11 carbon atoms (wherein, the methylene (-CH2-) group in the above alkyl group can be replaced by an oxygen (-O-) group),

[0045] R b14 and R b15 Each can be independently a straight-chain or branched alkyl group with 1 to 4 carbon atoms, an alkenyl group with 2 to 4 carbon atoms, an aryl group with 6 to 10 carbon atoms, an aryl-substituted alkyl group with 7 to 11 carbon atoms, or a halogen atom that can be substituted by a fluorine atom.

[0046] n13, n14, and n15 are each independently 0 to 2.

[0047]

[0048] (in the formula,

[0049] R b16 and R b17 Each of the following can be independently a hydroxyl group, a straight-chain or branched alkoxy group having 1 to 9 carbon atoms, a straight-chain or branched alkyl group having 1 to 10 carbon atoms that can be substituted with a fluorine atom, an alkenyl group having 2 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, or a halogen atom.

[0050] n16 is 0 to 3.

[0051] n17 is 0 to 2)

[0052] The reversible thermochromic microcapsule pigment of the present invention contains the above-mentioned reversible thermochromic composition.

[0053] The reversible thermochromic liquid composition of the present invention comprises the above-mentioned reversible thermochromic microcapsule pigment and color carrier.

[0054] The solid writing instrument or solid cosmetic of the present invention comprises the above-mentioned reversible thermochromic microcapsule pigment and excipient.

[0055] The reversible thermochromic molding resin composition of the present invention comprises the above-mentioned reversible thermochromic microcapsule pigment and molding resin.

[0056] The reversible thermochromic laminate of the present invention comprises a support and a reversible thermochromic layer containing the above-mentioned reversible thermochromic microcapsule pigment.

[0057] The writing instrument of the present invention contains writing ink comprising reversible thermochromic microcapsule pigments and a carrier.

[0058] The effects of the invention

[0059] According to the present invention, a reversible thermochromic composition that exhibits black color when chromogenic and colorless color when dechromogenic, and has excellent lightfastness, and a reversible thermochromic microcapsule pigment encapsulating the reversible thermochromic composition are provided. They also have high concentrations in their chromogenic state, and furthermore, a large difference between the concentrations in their chromogenic and dechromogenic states (excellent contrast between the chromogenic and dechromogenic states). Attached Figure Description

[0060] Figure 1 is a graph illustrating the hysteresis characteristics in the color concentration-temperature curve of the heat-decolorizing reversible thermochromic composition.

[0061] Figure 2 is a graph illustrating the hysteresis characteristics in the color concentration-temperature curve of a heat-induced reversible thermochromic composition with color memory properties.

[0062] Figure 3 is a graph illustrating the hysteresis characteristics in the color concentration-temperature curve of the heat-induced color-changing reversible thermochromic composition. Detailed Implementation

[0063] Examples of reversible thermochromic compositions of the present invention include, at least, a heat-decolorizing (decolorizing by heating and color developing by cooling) reversible thermochromic composition comprising at least three essential components: (a) an electron-donating chromogenic organic compound, (b) an electron-accepting compound, and (c) a reaction medium that determines the occurrence temperature of the color-developing reaction of components (a) and (b).

[0064] As the aforementioned reversible thermochromic composition, a heat-decolorizing type (decolorizing by heating and color developing by cooling) reversible thermochromic composition as described in Japanese Patent Publication Nos. 51-44706, 51-44707, and 1-29398 can be used. This reversible thermochromic composition has the characteristic of having a small hysteresis width (ΔH) (ΔH = 1 to 7°C): it changes color before and after a specified temperature (color change point), exhibits a decolorizing state in the temperature region above the color change point on the high-temperature side, and exhibits a color developing state in the temperature region below the color change point on the low-temperature side. Of the two states, only one specific state exists in the room temperature region, and the other state is maintained during the application of heat or cold required to exhibit that state, but if heat or cold is not applied, it returns to the state exhibited in the room temperature region (see Figure 1).

[0065] Alternatively, reversible thermochromic compositions of the heat-decolorizing type (decolorizing by heating and color-developing by cooling) as described in Japanese Patent Application Publications No. 4-17154, 7-179777, 7-33997, 8-39936, and 2005-1369 may be used. These reversible thermochromic compositions exhibit a large hysteresis width (ΔH = 8–70°C), effectively mitigating the change in color concentration caused by temperature variations. The shape of the curve obtained by plotting it changes color along very different paths when the temperature rises from the lower side compared to the color change temperature region and when it falls from the higher side compared to the color change temperature region. The color state in the temperature region below the complete color development temperature t1, or the color-decolorizing state in the high temperature region above the complete color decolorization temperature t4, has color memory in a specific temperature region [the temperature region between the color development start temperature t2 and the color decolorization start temperature t3 (the actual two-phase retention temperature region)] (see Figure 2).

[0066] The following provides a detailed explanation of each of the components (a), (b), and (c).

[0067] (a) Component, namely electron-donating chromogenic organic compounds, are the components that determine color. They are compounds that donate electrons to (b) component, which acts as a chromogenic agent, to produce color.

[0068] (a) The composition is the compound shown in formula (A).

[0069]

[0070] In the formula,

[0071] R a1 It can be methyl or ethyl, preferably ethyl.

[0072] R a2 It is a methyl group.

[0073] p is 1 or 2, preferably 1.

[0074] Among them, R a1 and all R a2 The total number of carbon atoms is 2 or 3, preferably 3.

[0075] R a3 It is a halogen atom, a straight-chain or branched alkyl group having 1 to 4 carbon atoms, or a straight-chain or branched alkoxy group having 1 to 3 carbon atoms, preferably a halogen atom or a straight-chain or branched alkyl group having 1 to 4 carbon atoms.

[0076] q can be 0 or 1, preferably 0.

[0077] Examples of compounds represented by formula (A) include 2-anilino-3-methyl-6-(N-ethyl-N-p-tolylamino)fluorane.

[0078] The reversible thermochromic composition of the present invention, which utilizes the fluorane derivative shown in formula (A), exhibits a black color when it develops color and becomes colorless when it decolorizes. Furthermore, the concentration difference between the color-developing state and the decolorizing state is large, i.e., the contrast between the color-developing state and the decolorizing state is excellent. Furthermore, even with repeated temperature changes, the reversible thermochromic composition is not easily impaired in its reversible thermochromic function of becoming a decolorized state in the temperature region above the high-temperature side color change point (complete decolorization temperature) and a color-developing state in the temperature region below the low-temperature side color change point (complete color development temperature). Moreover, even with repeated use, the concentrations of the color-developing state and the decolorizing state are not easily altered.

[0079] (b) Component, namely, an electron-accepting compound, is a compound that accepts electrons from component (a) and acts as a colorimetric agent for component (a).

[0080] (b) The component is at least one of the compounds represented by the following formulas (B1), (B2), (B3), (B4) and (B5).

[0081] The compound represented by formula (B1) is as follows.

[0082]

[0083] In the formula,

[0084] R b1 It is a hydrogen atom, a straight-chain or branched alkyl group having 1 to 17 carbon atoms, or an aryl group having 6 to 10 carbon atoms, preferably a hydrogen atom or a methyl group.

[0085] R b2 It is a straight-chain or branched alkyl group having 1 to 17 carbon atoms (wherein the methylene (-CH2-) group in the alkyl group can be replaced by an oxy (-O-) group, a carbonyl (-CO-) group, or an imino (-NH-) group), or an aryl group having 6 to 10 carbon atoms.

[0086] Preferably, it is a straight-chain or branched alkyl or phenyl group with 3 to 11 carbon atoms.

[0087] More preferably, it is a branched alkyl or phenyl group having 5 to 9 carbon atoms.

[0088] In addition, in this invention, the aryl group also includes alkyl-substituted aryl groups (e.g., tolyl). The same applies to the following aryl groups.

[0089] Among them, R b1 With R b2They can form a ring together; in the case of ring formation, it is preferable to form a cyclohexane ring that can be substituted with a methyl group. R b1 With R b2 Not forming a ring is also a suitable solution.

[0090] R b3 and R b4 Each of the following can be a straight-chain or branched alkyl group with 1 to 4 carbon atoms, an alkenyl group with 2 to 4 carbon atoms, an aryl group with 6 to 10 carbon atoms, or a halogen atom that can be replaced by a fluorine atom or a hydroxyl group, preferably a straight-chain or branched alkyl group (more preferably methyl) or a halogen atom (more preferably fluorine atom) with 1 to 4 carbon atoms.

[0091] Among them, all R b1 ~R b4 The total number of carbon atoms is 3 or more.

[0092] n3 and n4 are each independently 0 to 2, preferably 0 or 1, more preferably 0. In a further preferred embodiment, the hydroxyl groups are each located at the 4-position (para-position) of the benzene ring.

[0093] As a specific example of (B1), the following can be cited.

[0094] 1,1-bis(4-hydroxyphenyl)n-hexane,

[0095] 1,1-bis(4-hydroxyphenyl)n-octane,

[0096] 1,1-Bis(4-hydroxyphenyl)-n-decane,

[0097] 1,1-Bis(4-hydroxyphenyl)-2-methylpropane,

[0098] 1,1-Bis(4-hydroxyphenyl)-2-ethylbutane,

[0099] 1,1-Bis(4-hydroxyphenyl)-2-ethylhexane,

[0100] 1,1-Bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane,

[0101] 1-Phenylacetylene-1,1-bis(4-hydroxyphenyl)methane,

[0102] 2,2-bis(4-hydroxyphenyl)n-heptane,

[0103] 2,2-bis(4-hydroxyphenyl)-dodecane,

[0104] 1-Phenylacetane, 1,1-bis(4-hydroxyphenyl)ethane

[0105] 2,2-bis(4-hydroxyphenyl)-4-methylhexane,

[0106] 2,2-bis(4-hydroxy-3-methylphenyl)butane,

[0107] 2,2-bis(4-hydroxy-3-isopropylphenyl)propane,

[0108] 2,2-bis(3-fluoro-4-hydroxyphenyl)propane,

[0109] 9,9-Bis(4-hydroxy-3-methylphenyl)fluorene

[0110] The compound represented by formula (B2) is as follows.

[0111]

[0112] In the formula,

[0113] R b5 It is a hydrogen atom or a straight-chain or branched alkyl group having 1 to 6 carbon atoms, preferably a hydrogen atom or a methyl group.

[0114] L is a single bond, a straight-chain or branched alkylene group with 1 to 3 carbon atoms, an aryl-substituted alkylene group with 7 to 9 carbon atoms, or an arylene group with 6 to 10 carbon atoms.

[0115] Preferably, it is a single bond, an ethylene, or a group represented by formula (i).

[0116] More preferably, it is a single bond or a group represented by formula (i).

[0117]

[0118] (Regarding the group shown in formula (i), the benzene ring is bonded to the carbon atom indicated in formula (B2))

[0119] R b6 R b7 and R b8 Each of the following can be a straight-chain or branched alkyl group having 1 to 4 carbon atoms, 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 methyl or ethyl), a straight-chain or branched alkoxy group having 1 to 3 carbon atoms (more preferably methoxy or ethoxy), a cyclohexyl group, or a halogen atom (more preferably a fluorine atom).

[0120] n6, n7, and n8 are each independently 0 to 3, preferably 0 or 1, and more preferably 0. In a further preferred embodiment, each hydroxyl group is located at the 4-position (para-position) of the benzene ring.

[0121] As a specific example of (B2), the following can be cited.

[0122] 4,4',4”-Methylenetriphenol

[0123] 4,4'-[(4-hydroxyphenyl)methylene]bis(2-methylphenol),

[0124] 4,4'-[(4-hydroxyphenyl)methylene]bis(2-cyclohexyl-5-methylphenol),

[0125] 4,4',4”-Methethyltriphenol,

[0126] 4,4',4”-Methethyltris(2-methylphenol),

[0127] 4,4'-[1-{4-〔1-(4-hydroxyphenyl)-1-methylethyl〕phenyl}ethylidene]bisphenol,

[0128] 4,4'-[1-{4-〔1-(4-hydroxy-3-methylphenyl)-1-methylethyl〕phenyl}ethylene]bis(2-methylphenol),

[0129] 4,4'-[(3-ethoxy-4-hydroxyphenyl)methylene]bisphenol,

[0130] 4,4'-[3-(5-cyclohexyl-4-hydroxy-2-methylphenyl)-3-phenyl)propylidene]bis(2-cyclohexyl-5-methylphenol),

[0131] 4,4'-[(4-hydroxyphenyl)methylene]bis(2-isopropylphenol),

[0132] 4,4'-[1-{4-〔1-(3-fluoro-4-hydroxyphenyl)-1-methylethyl〕phenyl}ethylidene]bisphenol, 4,4'-[3-(2,5-dimethyl-4-hydroxyphenyl)butylidene]bis(2,5-dimethylphenol),

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

[0134] 1,2,2-Tris(4-hydroxyphenyl)propane,

[0135] 1,3,3-Tris(4-hydroxyphenyl)butane,

[0136] 1,4,4-Tris(4-hydroxyphenyl)pentane,

[0137] 2,2-Bis(3-methyl-4-hydroxyphenyl)-1-(4-hydroxyphenyl)propane,

[0138] 1-(3-methyl-4-hydroxyphenyl)-2,2-bis(4-hydroxyphenyl)propane,

[0139] 1-(3-methyl-4-hydroxyphenyl)-3,3-bis(4-hydroxyphenyl)butane,

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

[0141] 1,1,3-Tris(3-methyl-4-hydroxyphenyl)propane,

[0142] 1,3,3-Tris(3-methyl-4-hydroxyphenyl)butane,

[0143] 4,4'-〔4-(4-hydroxyphenyl)-sec-butylene〕bis(2-methylphenol)

[0144] The compound represented by formula (B3) is as follows.

[0145]

[0146] In the formula,

[0147] R b9 It is a straight-chain or branched alkyl group with 1 to 4 carbon atoms that has been replaced by fluorine atoms.

[0148] Preferred to be trifluoromethyl, pentafluoroethyl, or trifluoroethyl.

[0149] More preferably, it is trifluoromethyl.

[0150] R b10 It is a straight-chain or branched alkyl group with 1 to 4 carbon atoms that can be replaced by fluorine atoms, or an aryl group with 6 to 10 carbon atoms.

[0151] Preferably, it is a straight-chain or branched alkyl group with 1 to 4 carbon atoms that has been substituted with fluorine atoms.

[0152] More preferably, it is trifluoromethyl, pentafluoroethyl, or trifluoroethyl.

[0153] Trifluoromethyl is a further preferred formulation.

[0154] Among them, R b9 With R b10 They can form a ring together, but it is preferable that they do not form a ring.

[0155] R b11 and R b12Each of the following can be an alkyl group with 1 to 4 carbon atoms that can be replaced by a fluorine atom or a hydroxyl group, either a straight-chain or branched alkyl group, an alkenyl group with 2 to 4 carbon atoms, an aryl group with 6 to 10 carbon atoms, or a halogen atom, preferably a straight-chain or branched alkyl group with 1 to 4 carbon atoms (more preferably methyl), or a straight-chain or branched alkyl group with 1 to 4 carbon atoms that has been replaced by a hydroxyl group (more preferably hydroxymethyl).

[0156] n11 and n12 are each independently 0 to 2, preferably 0 or 1, more preferably 0. In a further preferred embodiment, the hydroxyl groups are each located at the 4-position (para-position) of the benzene ring.

[0157] As a specific example of (B3), the following can be cited.

[0158] 2,2-bis(4-hydroxyphenyl)-1,1,1-trifluoropropane,

[0159] 2-Phenyl-2,2-bis(4-hydroxyphenyl)-1,1,1-trifluoroethane,

[0160] 2,2-bis(4-hydroxyphenyl)hexafluoropropane,

[0161] 2,2-Bis(4-hydroxy-3-methylphenyl)hexafluoropropane,

[0162] 2,2-Bis(3,5-dihydroxymethyl-4-hydroxyphenyl)hexafluoropropane

[0163] The compound represented by formula (B4) is as follows.

[0164]

[0165] In the formula,

[0166] R b13 It can be a hydrogen atom, a straight-chain or branched alkyl group with 1 to 4 carbon atoms, an alkenyl group with 2 to 4 carbon atoms, an aryl group with 6 to 10 carbon atoms, or an aryl-substituted alkyl group with 7 to 11 carbon atoms (wherein, the methylene (-CH2-) group in the alkyl group can be replaced by an oxygen (-O-) group).

[0167] Preferably, it is a straight-chain or branched alkyl group with 1 to 3 carbon atoms, or an aryl-substituted alkyl group with 7 or 8 carbon atoms.

[0168] More preferably, it is isopropyl or benzyl.

[0169] R b14 and R b15Each of the following can be a straight-chain or branched alkyl group with 1 to 4 carbon atoms that can be replaced by a fluorine atom: an alkenyl group with 2 to 4 carbon atoms, an aryl group with 6 to 10 carbon atoms, an aryl-substituted alkyl group with 7 to 11 carbon atoms, or a halogen atom. Preferably, it is a straight-chain or branched alkyl group with 1 to 4 carbon atoms (more preferably methyl), an alkenyl group with 2 to 4 carbon atoms (more preferably 2-propenyl), an aryl-substituted alkyl group with 7 or 8 carbon atoms (more preferably benzyl, methylbenzyl, or phenethyl), or a halogen atom (more preferably chlorine or bromine).

[0170] n13, n14, and n15 are each independently 0 to 2, with n13 preferably being 1, and n14 and n15 preferably being 0 or 1, more preferably each being 0. In a further preferred embodiment, the hydroxyl group is present at the 4-position (para-position) of at least one benzene ring.

[0171] As a specific example of (B4), the following can be cited.

[0172] bis(4-hydroxyphenyl) sulfone,

[0173] 4-Benzyloxy-4'-hydroxydiphenyl sulfone,

[0174] 4-(4-methylbenzyloxy)-4'-hydroxydiphenyl sulfone,

[0175] 4-(4-n-propylbenzyloxy)-4'-hydroxydiphenyl sulfone,

[0176] 4-(4-isopropylbenzyloxy)-4'-hydroxydiphenyl sulfone,

[0177] 2,4'-Dihydroxydiphenyl sulfone,

[0178] 4-Hydroxydiphenyl sulfone,

[0179] 4-Methyl-4'-hydroxydiphenyl sulfone,

[0180] 4-n-propyl-4'-hydroxydiphenyl sulfone,

[0181] 4-Isopropyl-4'-hydroxydiphenyl sulfone,

[0182] 4-Methoxy-4'-hydroxydiphenyl sulfone,

[0183] 4-Propoxy-4'-hydroxydiphenyl sulfone,

[0184] 4-Isopropoxy-4'-hydroxydiphenyl sulfone,

[0185] 4-(2-Propyleneoxy)-4'-Hydroxydiphenylsulfone,

[0186] 4-(β-phenoxyethoxy)-4'-hydroxydiphenyl sulfone,

[0187] bis[4-hydroxy-3-(2-propenyl)phenyl] sulfone,

[0188] bis(3,5-dibromo-4-hydroxyphenyl) sulfone,

[0189] bis(4-hydroxy-3-n-propylphenyl) sulfone,

[0190] bis(4-hydroxy-3-methylphenyl) sulfone,

[0191] 3',4'-Dihydroxy-4-methyldiphenyl sulfone,

[0192] 3,4,4'-Trihydroxydiphenyl sulfone,

[0193] bis(3,4-dihydroxyphenyl) sulfone,

[0194] 2,3,4-Trihydroxydiphenyl sulfone,

[0195] 3-Benzyl-4-benzyloxy-4'-hydroxydiphenyl sulfone,

[0196] 3-Phenylacetyl-4-phenethoxy-4'-hydroxydiphenyl sulfone,

[0197] 3-Methylbenzyl-4-methylbenzyloxy-4'-hydroxydiphenyl sulfone,

[0198] 4-Benzyloxy-3'-benzyl-4'-hydroxydiphenyl sulfone,

[0199] 4-Phenylacetoxy-3'-Phenethyl-4'-Hydroxydiphenylsulfone,

[0200] 4-Methylbenzyloxy-3'-methylbenzyl-4'-hydroxydiphenylsulfone

[0201] The compound represented by formula (B5) is as follows.

[0202]

[0203] In the formula,

[0204] R b16 and R b17 Each of the following can be independently a hydroxyl group, a straight-chain or branched alkoxy group having 1 to 9 carbon atoms, a straight-chain or branched alkyl group having 1 to 10 carbon atoms that can be substituted with a fluorine atom, an alkenyl group having 2 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, or a halogen atom.

[0205] Preferably, it contains hydroxyl groups or straight-chain or branched alkyl groups having 1 to 8 carbon atoms.

[0206] More preferably, it is a hydroxyl group or a straight-chain or branched alkyl group having 3 to 5 carbon atoms.

[0207] Further preferred are hydroxyl, isobutyl, sec-butyl, and tert-butyl.

[0208] n16 is 0 to 3, preferably 1. n17 is 0 to 2, preferably 1. In a further preferred embodiment, the hydroxyl group is present at the 2-position (ortho) and the 4-position (para) of a benzene ring.

[0209] As a specific example of (B5), the following can be cited.

[0210] 2,4-Dihydroxybenzophenone

[0211] 4,4'-Dihydroxybenzophenone

[0212] 2,4-Dihydroxy-4'-n-propylbenzophenone

[0213] 2,4-Dihydroxy-4'-n-Butylbenzophenone

[0214] 2,4-Dihydroxy-4'-isobutylbenzophenone

[0215] 2,4-Dihydroxy-4'-sec-butylbenzophenone

[0216] 2,4-Dihydroxy-4'-tert-butylbenzophenone

[0217] 2,4-Dihydroxy-4'-n-hexylbenzophenone

[0218] 2,4-Dihydroxy-4'-(2-propenyl)benzophenone

[0219] 2,4-Dihydroxy-2',4'-Dimethylbenzophenone

[0220] 2,4-Dihydroxy-2',4',6'-trimethylbenzophenone

[0221] 2,4-Dihydroxy-2'-methoxybenzophenone

[0222] 2,4-Dihydroxy-4'-ethoxybenzophenone

[0223] 2,4-Dihydroxy-2',4'-Dimethoxybenzophenone

[0224] 2,4-Dihydroxy-3',4'-diethoxybenzophenone

[0225] By including at least one compound of formulas (B1) to (B5) as component (b), a reversible thermochromic composition can be provided that exhibits black color when chromogenic, changes colorless when dechromogenic, and has excellent lightfastness in the chromogenic state. Specifically, even in the chromogenic state, the decrease in concentration can be suppressed after exposure to light for a certain period of time.

[0226] As component (b), it is also preferable to use two or more compounds among the compounds shown in formulas (B1) to (B5), because by using multiple compounds together, the properties of each compound can be utilized to create a reversible thermochromic composition with superior properties.

[0227] Furthermore, it is more preferable to include the compound shown in formula (B1) as the compound, which can result in a low achromatic concentration. Even more preferably, it is preferable to combine the compound shown in formula (B1) with compounds other than those shown in formula (B1), which can increase the color concentration compared to using the compound shown in formula (B1) alone.

[0228] As the compound represented by formula (B1), R is preferred. b1 R is a hydrogen atom or a methyl group. b2 It is a compound consisting of a straight-chain or branched alkyl or phenyl group having 3 to 11 carbon atoms, where n3 and n4 are both 0, and each hydroxyl group is located at the 4-position (para-position) of the benzene ring. More preferably, it is R. b1 R is a hydrogen atom or a methyl group. b2 Compounds that are branched alkyl or phenyl groups with 5 to 9 carbon atoms, where n3 and n4 are both 0, and the hydroxyl groups are each located at the 4-position (para-position) of the benzene ring.

[0229] Among the compounds represented by formulas other than (B1), namely formulas (B2) to (B5), the compound represented by formula (B2) is readily available and exhibits excellent productivity. Therefore, the combination of the compound represented by formula (B1) and the compound represented by formula (B2) is the most preferred from the viewpoints of lightfastness, color intensity, and productivity.

[0230] As a compound of formula (B2) combined with the compound shown in formula (B1), R is preferred. b5 L is a hydrogen atom or a methyl group, L is a single bond, an ethylene, or a group shown in formula (i), n6, n7, and n8 are each 0 or 1, and R b6 R b7 and R b8 Each compound is independently methyl, ethyl, methoxy, ethoxy, or cyclohexyl, with each hydroxyl group located at the 4-position (para-position) of the benzene ring. More preferably, R... b5 A compound in which n is a hydrogen atom or a methyl group, L is a single bond or a group shown in formula (i), n6, n7 and n8 are each 0, and the hydroxyl group is located at the 4 position (para position) of the benzene ring.

[0231] That is, R is most suitable as the compound shown in formula (B1). b1 R is a hydrogen atom or a methyl group. b2Compounds consisting of branched alkyl or phenyl groups with 5 to 9 carbon atoms, where n3 and n4 are both 0, and hydroxyl groups are each present at the 4-position (para-position) of the benzene ring, and R as the compound shown in formula (B2). b5 A combination of compounds in which n is a hydrogen atom or a methyl group, L is a single bond or a group shown in formula (i), n6, n7 and n8 are each 0, and hydroxyl groups are each present at the 4 position (para position) of the benzene ring.

[0232] Component (c) of the reaction medium that enables the electron transfer reactions of components (a) and (b) to occur reversibly in a specific temperature region is described.

[0233] Examples of components (c) include alcohols, esters, ketones, ethers, and acid amides.

[0234] When the reversible thermochromic composition of the present invention is applied to microencapsulation and secondary processing, low molecular weight substances evaporate out of the capsule if subjected to high heat treatment. Therefore, in order to stably retain them inside the capsule, it is suitable to use compounds with more than 10 carbon atoms.

[0235] As alcohols, aliphatic monohydric saturated alcohols with more than 10 carbon atoms are effective.

[0236] As esters, esters with 10 or more carbon atoms are valid. Examples include esters obtained by any combination of aliphatic and monocarboxylic acids having alicyclic or aromatic rings with aliphatic and monohydric alcohols having alicyclic or aromatic rings; esters obtained by any combination of aliphatic and polycarboxylic acids having alicyclic or aromatic rings with aliphatic and monohydric alcohols having alicyclic or aromatic rings; and esters obtained by any combination of aliphatic and monocarboxylic acids having alicyclic or aromatic rings with aliphatic and polyhydric alcohols having alicyclic or aromatic rings.

[0237] In addition, ester compounds selected from esters of saturated fatty acids and branched aliphatic alcohols, esters of unsaturated fatty acids or saturated fatty acids with branches or substituents and branched or aliphatic alcohols with 16 or more carbon atoms, cetyl butyrate, stearyl butyrate, and benzyl butyrate are also effective.

[0238] Furthermore, in order to exhibit a large hysteresis characteristic in relation to the color concentration-temperature curve and to give color memory dependent on temperature changes, an example can be the carboxylic acid ester compound that shows a ΔT value (melting point-cloud point) of 5°C or higher and less than 50°C as described in Japanese Patent Publication No. 4-17154.

[0239] In addition, fatty acid ester compounds obtained by combining an odd-numbered aliphatic monohydric alcohol with 9 or more carbon atoms with an even-numbered aliphatic carboxylic acid, and fatty acid ester compounds with a total carbon number of 17 to 23 obtained by combining n-pentyl alcohol or n-heptyl alcohol with an even-numbered aliphatic carboxylic acid with 10 to 16 carbon atoms are also effective.

[0240] As ketones, aliphatic ketones with a total carbon number of 10 or more are effective, and arylalkyl ketones with a total carbon number of 12 to 24 can be cited as examples.

[0241] Aliphatic ethers with a total carbon number of 10 or more are effective as ethers.

[0242] Examples of the aforementioned alcohols, esters, ketones, ethers, and acid amides include, for instance, the compounds described in Japanese Patent Application Publication No. 2020-100710.

[0243] In addition, as component (c), it can also be a compound as shown in formula (1) below.

[0244]

[0245] In the formula, R1 represents a hydrogen atom or a methyl group, m represents an integer from 0 to 2, and either X1 or X2 represents -(CH2). n OCOR2 or (CH2) n COOR2, the other represents a hydrogen atom, n represents an integer from 0 to 2, R2 represents an alkyl or alkenyl group with 4 or more carbon atoms, Y1 and Y2 each independently represent any one of hydrogen atom, alkyl group with 1 to 4 carbon atoms, methoxy group, or halogen atom, and r and p each independently represent an integer from 1 to 3.

[0246] In the case where R1 in the compound shown in formula (1) is a hydrogen atom, it is preferred to obtain a reversible thermochromic composition with a wider hysteresis width. It is even more preferred that R1 is a hydrogen atom and m is 0.

[0247] Furthermore, among the compounds shown in formula (1), the compounds shown in formula (2) below are more preferred.

[0248]

[0249] (In the formula, R represents an alkyl or alkenyl group with 8 or more carbon atoms, preferably an alkyl group with 10 to 24 carbon atoms, and more preferably an alkyl group with 12 to 22 carbon atoms.)

[0250] Furthermore, as component (c), it can also be a compound as shown in formula (3) below.

[0251]

[0252] (In the formula, R represents an alkyl or alkenyl group with 8 or more carbon atoms, m and n each independently represent an integer from 1 to 3, and X and Y each independently represent any one of a hydrogen atom, an alkyl group with 1 to 4 carbon atoms, an alkoxy group with 1 to 4 carbon atoms, or a halogen atom.)

[0253] Furthermore, as component (c), it can also be a compound as shown in formula (4) below.

[0254]

[0255] (In the formula, X represents any one of hydrogen atom, alkyl group with 1 to 4 carbon atoms, methoxy group, or halogen atom; m represents an integer from 1 to 3; and n represents an integer from 1 to 20.)

[0256] Furthermore, as component (c), it can also be a compound as shown in formula (5) below.

[0257]

[0258] (In the formula, R represents an alkyl or alkenyl group with 1 to 21 carbon atoms, and n represents an integer from 1 to 3.)

[0259] Furthermore, as component (c), it can also be a compound as shown in formula (6) below.

[0260]

[0261] (In the formula, X represents any one of hydrogen atom, alkyl group with 1 to 4 carbon atoms, alkoxy group with 1 to 4 carbon atoms, or halogen atom, m represents an integer from 1 to 3, and n represents an integer from 1 to 20)

[0262] Furthermore, as component (c), it can also be a compound as shown in formula (7) below.

[0263]

[0264] (In the formula, R represents any one of alkyl, cycloalkylalkyl, cycloalkyl, and alkenyl with 4 to 22 carbon atoms, X represents any one of hydrogen atom, alkyl with 1 to 4 carbon atoms, alkoxy with 1 to 4 carbon atoms, and halogen atom, and n represents 0 or 1)

[0265] Furthermore, as component (c), it can also be a compound represented by the following formula (8).

[0266]

[0267] (In the formula, R represents an alkyl group with 3 to 18 carbon atoms or an aliphatic acyl group with 3 to 18 carbon atoms, X represents any one of a hydrogen atom, an alkyl group with 1 to 3 carbon atoms, an alkoxy group with 1 or 2 carbon atoms, or a halogen atom, Y represents a hydrogen atom or a methyl group, and Z represents any one of a hydrogen atom, an alkyl group with 1 to 4 carbon atoms, an alkoxy group with 1 or 2 carbon atoms, or a halogen atom)

[0268] Furthermore, as component (c), it can also be a compound represented by the following formula (9).

[0269]

[0270] (In the formula, R represents any one of alkyl, alkenyl, cycloalkylalkyl, or cycloalkyl groups with 4 to 22 carbon atoms, X represents any one of hydrogen, alkyl, alkoxy, or halogen atom, Y represents any one of hydrogen, alkyl, alkoxy, or halogen atom, and n represents 0 or 1)

[0271] Furthermore, as component (c), it can also be a compound represented by the following formula (10).

[0272]

[0273] (In the formula, R represents any one of alkyl with 3 to 18 carbon atoms, cycloalkyl with 6 to 11 carbon atoms, cycloalkyl with 5 to 7 carbon atoms, and alkenyl with 3 to 18 carbon atoms; X represents any one of hydrogen atom, alkyl with 1 to 4 carbon atoms, alkoxy with 1 to 3 carbon atoms, and halogen atom; Y represents any one of hydrogen atom, alkyl with 1 to 4 carbon atoms, methoxy, ethoxy, and halogen atom)

[0274] Furthermore, as component (c), it can also be a compound as shown in formula (11) below.

[0275]

[0276] (In the formula, R represents a cycloalkyl group with 3 to 8 carbon atoms or a cycloalkyl group with 4 to 9 carbon atoms, and n represents an integer from 1 to 3)

[0277] Furthermore, as component (c), it can also be a compound as shown in formula (12) below.

[0278]

[0279] (In the formula, R represents any one of alkyl with 3 to 17 carbon atoms, cycloalkyl with 3 to 8 carbon atoms, or cycloalkylalkyl with 5 to 8 carbon atoms; X represents any one of hydrogen atom, alkyl with 1 to 5 carbon atoms, methoxy, ethoxy, or halogen atom; and n represents an integer from 1 to 3.)

[0280] As the compounds shown in formulas (2) to (12), for example, the compounds described in Japanese Patent Application Publication No. 2020-100710 can be used.

[0281] Of the components in (c) above, considering the excellent solubility of component (a) in the reversible thermochromic composition, compounds having one or more aromatic rings are preferred, as they readily become reversible thermochromic compositions that increase the color intensity. More preferably, compounds having two or more aromatic rings are those shown in formulas (1) to (12).

[0282] In addition, reversible thermochromic compositions that use gallic acid esters (Japanese Patent Publication No. 51-44706, Japanese Patent Application Publication No. 2003-253149) as electron-accepting compounds, which are heat-generating (color develops by heating and decolorizes by cooling), and reversible thermochromic microcapsule pigments containing the reversible thermochromic compositions can also be applied (see Figure 3).

[0283] The reversible thermochromic composition of the present invention is a compatibilizer with the above-mentioned components (a), (b), and (c) as essential components. The proportion of each component is affected by the concentration, color change temperature, color change morphology, and type of each component. However, in general, the mass ratio of component (a): component (b) to obtain the desired characteristics is preferably 1:0.1 to 1:100, more preferably 1:0.1 to 1:50, and even more preferably in the range of 1:0.5 to 1:20.

[0284] Furthermore, the mass ratio of component (a) to component (c) is preferably 1:5 to 1:100, more preferably 1:5 to 1:50, even more preferably 1:5 to 1:20, and particularly preferably in the range of 1:5 to 1:15. By keeping the mass ratio of component (a) to component (c) within the above range, it is easy to obtain a reversible thermochromic composition with a large concentration difference between the chromogenic concentration and the achromogenic concentration, that is, with a more superior contrast between the chromogenic state and the achromogenic state.

[0285] Furthermore, various light stabilizers can be blended into the reversible thermochromic composition as needed.

[0286] The light stabilizer is contained to prevent photodegradation of the reversible thermochromic composition comprising components (a), (b), and (c), and is formulated in a ratio of 0.3 to 24 parts by mass relative to 1 part by mass of component (a), preferably 0.3 to 16 parts by mass. Furthermore, the light stabilizer contains an ultraviolet absorber that effectively blocks ultraviolet radiation from sunlight, preventing photodegradation caused by the excited state resulting from the photoreaction of component (a). Additionally, antioxidants, singlet oxygen quenchers, superoxide anion quenchers, ozone quenchers, etc., inhibit photo-induced oxidation reactions.

[0287] Light stabilizers can be used in one or more ways, or in appropriate combinations.

[0288] The reversible thermochromic composition of the present invention is effective even when applied directly, but it can also be encapsulated in microcapsules to form reversible thermochromic microcapsule pigments (hereinafter, sometimes referred to as "microcapsule pigments" or "pigments"), or dispersed in thermoplastic or thermosetting resins to form reversible thermochromic resin particles (hereinafter, sometimes referred to as "resin particles").

[0289] Reversible thermochromic compositions are preferably encapsulated in microcapsules to form reversible thermochromic microcapsule pigments. This is because encapsulation in microcapsules allows for the formation of chemically and physically stable pigments. Furthermore, under various usage conditions, the reversible thermochromic composition remains consistent in composition and can exert the same effect.

[0290] In addition, microencapsulation can be achieved through conventional methods such as isocyanate-based interfacial polymerization, melamine-formaldehyde in-situ polymerization, liquid-based curing coating, phase separation from aqueous solutions, phase separation from organic solvents, melt-dispersion-cooling, gas suspension coating, and spray drying, with the appropriate method selected depending on the application. Furthermore, a secondary resin film can be added to the surface of the microcapsules to impart durability, or the surface properties can be modified for practical use, depending on the intended purpose.

[0291] The reversible thermochromic microcapsule pigment preferably has an encapsulation-to-wall-film mass ratio of 7:1 to 1:1. By keeping the encapsulation-to-wall-film mass ratio within this range, a decrease in color intensity and vividness during color development is prevented. More preferably, the encapsulation-to-wall-film mass ratio is 6:1 to 1:1.

[0292] The average particle size of the reversible thermochromic microcapsule pigments or resin particles is preferably 0.01–50 μm, more preferably 0.1–30 μm, and even more preferably 0.5–20 μm. If the average particle size of the microcapsule pigments or resin particles exceeds 50 μm, they lack dispersion stability and processing adaptability when blended into inks, coatings, or resins. On the other hand, if the average particle size is less than 0.01 μm, it is difficult to exhibit high concentrations of color development.

[0293] Furthermore, when microencapsulated pigments or resin particles are used in inks for writing instruments, the average particle size is preferably 0.01 to 5 μm, more preferably 0.05 to 4 μm, even more preferably 0.1 to 3 μm, and particularly preferably in the range of 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 flow 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 exhibit high concentrations of color development.

[0294] In addition, the average particle size was determined using image-analytical particle size distribution measurement software (Maintek Corporation, product name: MacBeau) to determine the region of the particle, and the diameter of the projected area equivalent circle (Heywood diameter) was calculated from the area of ​​the particle's region. This value was then used as the average particle size of the equivalent volume sphere based on this value.

[0295] Furthermore, when the particle size of all or most particles exceeds 0.2 μm, the average particle size can be determined using the particle size distribution measuring device (manufactured by Bekman Co., Ltd., product name: Multisizer4e) by the Co. method as equivalent to particles of equal volume spheres.

[0296] Furthermore, based on the values ​​measured using the aforementioned software or a measuring device employing the Coulter method, the volumetric particle size and average particle size can be measured using a calibrated laser diffraction / scattering particle size distribution measuring device [manufactured by Horiba Corporation, product name: LA-300].

[0297] Reversible thermochromic compositions, reversible thermochromic microcapsule pigments or resin particles, and other reversible thermochromic colorants are dispersed in a carrier containing water and / or organic solvents and various additives as needed to form ink compositions (hereinafter, sometimes referred to as "inks"), which can then be used as reversible thermochromic liquid compositions for printing inks used in screen printing, offset printing, color printing, gravure printing, coating machines, pad printing, etc.; coatings used in brush coating, jet coating, electrostatic coating, electrodeposition coating, curtain coating, roller coating, dip coating, etc.; inkjet inks; UV-curable inks; inks for writing instruments such as markers, ballpoint pens, fountain pens, and fountain pens; inks for coating tools; inks for stamps; painting pigments; cosmetics; and coloring liquids for fibers.

[0298] Various additives can be mixed into reversible thermochromic liquid compositions.

[0299] Examples of additives include resins, crosslinking agents, curing agents, desiccants, plasticizers, viscosity modifiers, dispersants, ultraviolet absorbers, antioxidants, light stabilizers, sedimentation inhibitors, smoothing agents, gelling agents, defoamers, matting agents, penetrants, pH adjusters, foaming agents, coupling agents, humectants, mildew inhibitors, preservatives, and rust inhibitors.

[0300] Examples of ink carriers used in writing instruments include oil-based ink carriers containing organic solvents and water-based ink carriers containing water and, if necessary, organic solvents.

[0301] When the carrier is water-based, a water-soluble organic solvent compatible with water can be mixed into the ink for writing instruments. The water-soluble organic solvent can inhibit the evaporation of water from the ink, prevent changes in the specific gravity of the carrier and maintain good dispersion stability of the reversible thermochromic microcapsule pigment, and stabilize the structure of the loose aggregates formed by the polymer agglomerates or polymer agglomerates and dispersants (described later).

[0302] Examples of organic solvents include ethanol, propanol, butanol, glycerol, sorbitol, triethanolamine, diethanolamine, monoethanolamine, ethylene glycol, diethylene glycol, thiodiethylene glycol, polyethylene glycol, propylene glycol, butanediol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, sulfolane, 2-pyrrolidone, N-methyl-2-pyrrolidone, etc.

[0303] When the ink for writing instruments contains a water-soluble organic solvent, the water-soluble organic solvent is preferably mixed in the range of 1 to 40% by mass, more preferably 5 to 30% by mass, and even more preferably 10 to 25% by mass relative to the total amount of 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, there is a lack of water evaporation inhibition effect.

[0304] When writing instrument inks contain water-soluble organic solvents, and the hysteresis width (ΔH) of the reversible thermochromic microcapsule pigments mixed in the writing instrument inks is large, the specific gravity of the microcapsule pigments is greater than 1. When adjusting the specific gravity of the carrier, it is easier to adjust the specific gravity by using water-soluble organic solvents with a specific gravity greater than water. Therefore, as a water-soluble organic solvent, glycerol or the like with a specific gravity greater than 1.1 is preferred.

[0305] Shear-thickness reducing agents can be added to writing inks. Ink containing shear-thickness reducing agents (shear-thickness reducing ink) can inhibit the aggregation and sedimentation of microcapsule pigments and inhibit the bleed-through of writing, thus forming good handwriting.

[0306] Furthermore, when the shear-reducing ink is contained in a ballpoint pen-shaped writing instrument, it is possible to prevent ink leakage from the gap between the ball and the tip when the writing instrument is not in use, or to prevent backflow of ink when the writing tip is placed upwards (upright position).

[0307] Examples of shear-reducing and viscosity-reducing agents include xanthan gum, vestigma, succinosaccharides (average molecular weight approximately 1 million to 8 million) that are organic acid-modified heteropolysaccharides composed of glucose and galactose as monosaccharides, alkagum, guar gum, locust bean gum and its derivatives, hydroxyethyl cellulose, alkyl alginates, polymers with molecular weights of 100,000 to 150,000 with alkyl methacrylates as the main component, glucomannan, agar, carrageenan and other thickening polysaccharides with gelling ability extracted from seaweed, benzyl sorbitol and benzyl xylitol or their derivatives. Derivatives, cross-linked acrylic polymers, inorganic microparticles, polyglycerol fatty acid esters, polyoxyethylene sorbitol 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 nonionic surfactants with HLB values ​​of 8-12, salts of dialkyl or diene sulfosuccinic acid, mixtures of N-alkyl-2-pyrrolidone and anionic surfactants, mixtures of polyvinyl alcohol and acrylic resins, etc.

[0308] In addition, polymeric agglomerates can be mixed into inks for writing instruments. Ink containing polymeric agglomerates (agglomerated inks) can improve the dispersibility of microcapsule pigments because the microcapsule pigments form loose aggregates through the polymeric agglomerates, inhibiting the microcapsule pigments from contacting each other and agglomerating.

[0309] Examples of polymeric flocculants include polyvinylpyrrolidone, polyethylene oxide, and water-soluble polysaccharides.

[0310] Examples of water-soluble polysaccharides include tragacanth gum, guar gum, pullulan, cyclodextrin, and water-soluble cellulose derivatives.

[0311] Furthermore, as water-soluble cellulose derivatives, examples include methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxyethylmethylcellulose, and hydroxypropylmethylcellulose.

[0312] Among the aforementioned polymeric flocculants, hydroxyethyl cellulose is preferred due to its excellent dispersibility.

[0313] The polymeric agglomerate is preferably mixed in the range of 0.1 to 1% by mass relative to the total amount of ink, more preferably in the range of 0.3 to 0.5% by mass. Within the above range, the microcapsule pigments can form loose aggregates, thus fully demonstrating the effect of improving pigment dispersibility.

[0314] Furthermore, the dispersibility of microcapsule pigments can be improved by mixing a dispersant into the ink used for writing instruments.

[0315] In addition, polymeric agglomerates and dispersants can be used together. When the two are used together, the dispersibility of microcapsule pigments can be improved, and the dispersibility of loose aggregates of microcapsule pigments formed by polymeric agglomerates can be further improved.

[0316] Examples of dispersants include polyvinylpyrrolidone, 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, and amine oligomers of polyesters.

[0317] Among the above dispersants, considering the excellent dispersibility of microcapsule pigments, acrylic polymeric dispersants are preferred, acrylic polymeric dispersants with carboxyl groups are more preferred, and acrylic polymeric dispersants with comb-like structures having carboxyl groups in their side chains are even more preferred.

[0318] As a dispersant, acrylic polymeric dispersants with a comb-like structure having multiple carboxyl groups on the side chain are particularly preferred. Specifically, an example is Lloyds Co., Ltd. of Japan, product name: Solspa 43000.

[0319] The dispersant is preferably mixed in the range of 0.01 to 2% by mass relative to the total amount of ink, more preferably in the range of 0.1 to 1.5% by mass. If the mixing ratio of the dispersant exceeds 2% by mass, the microcapsule pigments are prone to settling or floating when subjected to external vibration or the like. On the other hand, if the mixing ratio is less than 0.01% by mass, it is difficult to achieve the effect of improving dispersibility.

[0320] Furthermore, by mixing water-soluble resin into the ink used in writing instruments, it is possible to impart adhesion and stickiness to the paper surface with the pen strokes.

[0321] Examples of water-soluble resins include alkyd resins, acrylic resins, styrene-maleic acid copolymers, cellulose derivatives, polyvinylpyrrolidone, polyvinyl alcohol, and dextrin.

[0322] Among the above-mentioned water-soluble resins, polyvinyl alcohol is preferred due to its excellent stability as an acrylic polymeric dispersant. Furthermore, considering that the ink is highly soluble even in acidic regions, partially saponified polyvinyl alcohol with a saponification degree of 70 to 89 mol% is more preferred.

[0323] The water-soluble resin is preferably mixed in the range of 0.3 to 3.0% by mass relative to the total amount of ink, and more preferably in the range of 0.5 to 1.5% by mass.

[0324] Furthermore, when the viscosity of the carrier used in the ink for writing instruments is low, by mixing in a specific gravity regulator, the sedimentation or floating of microcapsule pigments in the ink can be suppressed, and the localized presence of microcapsule pigments can be improved.

[0325] The dispersion stability of pigments reaches its maximum when the specific gravity difference between the carrier and the pigment is extremely small. Specific gravity modifiers bring the specific gravity of the carrier closer to that of the pigment. Since the specific gravity of the carrier is affected by the specific gravity of the water-soluble substances dissolved in the carrier and their amount added, adding more specific gravity modifiers with a higher specific gravity to dissolve the carrier can increase the specific gravity of the carrier.

[0326] As a specific gravity regulator, it can be used for example, oxyacids and their salts of Group 6 elements in the atomic weight range of 90 to 185.

[0327] Such a specific gravity adjuster can be adjusted so that the specific gravity of the carrier is close to that of the pigment with a high specific gravity. Even if the ink has a low viscosity, it can suppress the pigment from settling or floating due to external stimulation such as vibration and thus maintain its local presence.

[0328] Oxyacids and their salts are selected from oxyacids and their salts of transition metal elements. These oxyacid ions are believed to form tetrahedrons or octahedrons, in which oxygen atoms are usually 4 or 6-coordinated with metal atoms.

[0329] As oxyacids and their salts, they can be polyacids and polyacid salts, including isopolyacids, heteropolyacids, etc., and polyacid salts including isopolyacid salts, heteropolyacid salts, etc.

[0330] Examples of specific gravity regulators include individual oxyacids and their salts, isopolyacids and their salts, heteropolyacids and their salts, etc.

[0331] Examples of oxyacids as standalone oxyacids include molybdic acid and tungstic acid. Examples of salts of standalone oxyacids include sodium molybdate, potassium molybdate, ammonium molybdate, sodium tungstate, potassium tungstate, ammonium tungstate, lithium tungstate, and magnesium tungstate.

[0332] Examples of isopolyacids include metamolybdic acid, secondary molybdic acid, metatungstic acid, secondary tungstic acid, and isotungstic acid. Furthermore, examples of isopolyacid salts include sodium metamolybdate, potassium metamolybdate, ammonium metamolybdate, sodium secondary molybdate, potassium secondary molybdate, ammonium secondary molybdate, sodium metatungstate, potassium secondary molybdate, ammonium secondary molybdate, sodium metatungstate, potassium secondary molybdate, ammonium secondary molybdate, barium metatungstate, sodium secondary tungstate, and sodium isotungstate.

[0333] Examples of heteropoly acids include phosphomolybdic acid, molybdic acid, tungstic phosphate, and tungstic silicic acid. Furthermore, examples of heteropoly acid salts include sodium phosphomolybdate, sodium molybdate, sodium tungstic phosphate, and sodium tungstic silicic acid.

[0334] The above-mentioned oxyacids and their salts may be used in one or in appropriate combinations of two or more.

[0335] Among the above-mentioned specific gravity adjusters, metatungstic acid, paratungstic acid, sodium metatungstate, potassium metatungstate, ammonium metatungstate, barium metatungstate, sodium paratungstate, sodium isotungstate, tungstic phosphate, tungstic silicate, sodium tungstic phosphate, and sodium tungstic silicate are preferred, and sodium isotungstate, sodium metatungstate, and sodium paratungstate are even more preferred.

[0336] Sodium isotungstate, sodium metatungstate, and sodium paratungstate are not only highly safe, but also have a high specific gravity, making it easy to adjust the specific gravity of the liquid according to the amount added, thus making them suitable for use.

[0337] The specific gravity modifier is preferably mixed in the range of 2 to 20% by mass relative to the total amount of ink, more preferably 5 to 15% by mass. If the mixing ratio of the specific gravity modifier exceeds 20% by mass, the microcapsule pigments are prone to agglomeration. On the other hand, if the mixing ratio is less than 2% by mass, the specific gravity adjustment effect of the carrier is lacking.

[0338] Furthermore, the mass ratio of microcapsule pigment to specific gravity regulator 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.

[0339] The carriers mixed with the above-mentioned specific gravity adjusters are particularly effective for microcapsule pigments with high specific gravity. Even if the ink has low viscosity, they can suppress pigment sedimentation in the ink under external stimulation such as vibration, thereby improving the dispersion stability of microcapsule pigments.

[0340] The specific gravity of microencapsulated pigments is influenced by particle size, the composition and content of the microcapsules, the composition and thickness of the capsule wall membrane, the coloring state of the pigment, and temperature. However, when the microencapsulated pigment is in a fully colored state, a specific gravity of 1.05–1.20 is suitable at 20°C with water as a reference. Such pigments exhibit a large hysteresis width (ΔH), and can be decolored by heating, maintaining the decolored state within a specific temperature range. However, pigments with a large hysteresis width (ΔH) often use compounds with two or more aromatic rings in the molecule as component (c), thus tending to have a high specific gravity and easily settle and separate in inks, especially under external stimuli such as vibration. However, in inks mixed with the aforementioned specific gravity modifiers, even with low viscosity inks, the sedimentation of microencapsulated pigments can be suppressed, resulting in localized presence and improved pigment dispersion stability, making them suitable for use.

[0341] If the dispersion stability of the pigment in the ink is taken into consideration, then when the microcapsule pigment is in a fully colored state and water is used as a reference at 20°C, the specific gravity of the microcapsule pigment is preferably 1.10 to 1.20, more preferably 1.12 to 1.15.

[0342] In addition, the specific gravity of microcapsule pigments can be determined by the following method.

[0343] (Specific gravity determination method for microencapsulated pigments)

[0344] 1. Add and mix 30 ml of glycerol aqueous solution and 1 g of fully colored microcapsule pigment in a threaded tube bottle to obtain a microcapsule pigment dispersion.

[0345] 2. Adjust 30 ml of the microcapsule pigment dispersion to 20°C and centrifuge at 1000 rpm for 30 seconds in a centrifuge. Alternatively, a cooled / benchtop centrifuge (manufactured by Kokusan Co., Ltd., product name: H103N) can be used as the centrifuge.

[0346] 3. Observe the microcapsule pigment dispersion.

[0347] With most of the microcapsule pigment precipitated at the bottom of the beaker, the state of the dispersion was observed by repeating steps 1-2 with an aqueous solution containing a higher concentration of glycerol compared to the glycerol aqueous solution at that time.

[0348] After confirming that most of the microcapsule pigments were suspended on the liquid surface, the state of the dispersion was observed again by using an aqueous solution with a lower glycerol concentration compared to the current glycerol aqueous solution.

[0349] The above series of operations is repeated until it is visually confirmed that the glycerol aqueous solution, except for the area near the bottom of the threaded tube, is uniformly colored, rather than being in a state where most of the microcapsule pigment has floated to the surface or precipitated. The specific gravity of the glycerol aqueous solution at this point is measured and set as the specific gravity of the microcapsule pigment. Alternatively, the specific gravity of the glycerol aqueous solution can be determined by using the float method described in JIS K0061 7.1, where the aqueous solution is heated to 20°C.

[0350] Furthermore, the color carrier containing the above-mentioned specific gravity adjuster has a specific gravity in the range of 1.00 to 1.30 when water is used as the reference substance at 20°C. More preferably, the specific gravity is 1.05 to 1.20, and more preferably 1.08 to 1.18.

[0351] Furthermore, the specific gravity of the color carrier relative to the specific gravity of the pigment is preferably 0.90 to 1.20 times, more preferably 0.95 to 1.10 times.

[0352] If the specific gravity of the carrier is within the above range, and the specific gravity of the carrier relative to the specific gravity of the pigment is within the above range, then even if the ink has low viscosity, the localization of pigment sedimentation in the ink can be further suppressed when external stimulation such as vibration is applied to the ink, thereby improving the dispersion stability of the pigment.

[0353] When the ink carrier for writing instruments is an aqueous ink carrier, the ink carrier contains at least water, and the water is preferably mixed in the range of 30 to 80% by mass, more preferably 40 to 70% by mass, relative to the total amount of ink.

[0354] Furthermore, when writing ink is used in ballpoint pens, it is preferable to add higher fatty acids such as oleic acid, nonionic surfactants with long-chain alkyl groups, polyether-modified silicone oil, trithiophosphite (alkoxycarbonylmethyl ester), trithiophosphite (alkoxycarbonylethyl ester), etc., monophosphate esters of polyoxyethylene alkyl ethers or polyoxyethylene alkyl aryl ethers, diesters of polyoxyethylene alkyl ethers or polyoxyethylene alkyl aryl ethers, or their metal salts, ammonium salts, amine salts, alkanolamine salts, etc., to the ink to prevent wear on the ball bearing.

[0355] In addition, depending on the requirements, wetting agents, resins, resin particles, pH adjusters, rust inhibitors, surfactants, humectants, defoamers, viscosity modifiers, preservatives, mildew inhibitors and other additives can also be mixed in.

[0356] In the aforementioned writing instrument ink, the reversible thermochromic microcapsule pigment is preferably mixed in a ratio of 5 to 40% by mass relative to the total ink volume, more preferably 10 to 40% by mass, and even more preferably 10 to 30% by mass. By keeping the mixing ratio of the microcapsule pigment within the above range, the desired color concentration can be obtained and the reduction in ink flowability can be prevented.

[0357] The ink composition of the present invention can be manufactured by any method known in the art. Specifically, it can be manufactured by mixing the necessary amounts of the above-mentioned components using various mixers such as propeller agitators, homogenizers, or homogenizers, or various dispersers such as bead mills.

[0358] When the writing ink of the present invention is used in a ballpoint pen, its viscosity at 20°C and at a rotational speed of 1 rpm (shear speed 3.84 seconds) is... -1 Under the conditions of [condition missing], considering the ability to suppress the sedimentation or aggregation of microcapsule pigments, a pressure of 1–2000 mPa·s is preferred, more preferably 3–1500 mPa·s, and even more preferably 500–1000 mPa·s. Furthermore, under conditions of 20°C and a rotational speed of 100 rpm (shear speed 384 s), [condition missing]. -1 Under the conditions specified, considering the good ink flowability from the pen tip, the viscosity is preferably 1 to 200 mPa·s, more preferably 10 to 100 mPa·s, and even more preferably 20 to 50 mPa·s. With the viscosity within the above range, the dispersion stability of the microcapsule pigments and the easy flowability of the ink within the pen's structure can be maintained at a high level.

[0359] Additionally, the viscosity was measured using a rheometer (TA Instrument Menthol Co., Ltd., product name: Discovery HR-2, cone plate (diameter 40mm, angle 1°)). The ink was placed in an environment of 20°C at a rotation speed of 1 rpm (shear speed 3.84 seconds). -1 ), or a rotation speed of 100 rpm (shearing speed 384 seconds). -1 The value was determined under the conditions of ).

[0360] When the writing ink of the present invention is used in a ballpoint pen, its surface tension is preferably 20 to 50 mN / m, more preferably 25 to 45 mN / m, at a temperature of 20°C. With the surface tension within the above range, it is easier to suppress the seepage of the writing line and its penetration into the paper, and the wettability of the ink on the paper can be improved.

[0361] In addition, the surface tension was measured using a surface tension meter (manufactured by Kyowa Interface Science Co., Ltd., product name: DY-300) by placing the ink at 20°C and using the vertical plate method with a platinum plate.

[0362] When the writing ink of the present invention is used in a ballpoint pen, its pH is preferably 3 to 10, more preferably 4 to 9. By keeping the pH within the above range, the aggregation or sedimentation of microcapsule pigments contained in the ink in low-temperature regions can be suppressed.

[0363] Additionally, the pH value was measured using a pH meter [manufactured by Aoya Discecek Co., Ltd., product name: IM-40S], with the ink placed in an environment of 20°C.

[0364] When the writing ink of the present invention is used in a marker, its viscosity, measured at 20°C and 30 rpm, is preferably 1–20 mPa·s, more preferably 1–10 mPa·s, and even more preferably 1–5 mPa·s. By maintaining the viscosity within the above range, the fluidity of the ink and the dispersion stability of the microcapsule pigments can be improved.

[0365] In addition, the viscosity was measured using a BL type rotational viscometer (manufactured by Toki Sangyo Co., Ltd., product name: TVB-M type viscometer, L type rotor), with the ink placed in an environment of 20°C.

[0366] When the writing ink of the present invention is used in a marker, its surface tension is preferably 25 to 50 mN / m, more preferably 25 to 45 mN / m, and even more preferably 35 to 45 mN / m at 20°C. With the surface tension within the above range, it is easier to suppress the seepage of the writing line and the bleed-through of the paper, and the wettability of the ink on the paper surface can be improved.

[0367] In addition, the surface tension was measured using a surface tension meter (manufactured by Kyowa Interface Science Co., Ltd., product name: DY-300) by placing the ink at 20°C and using the vertical plate method with a glass plate.

[0368] When the writing ink of the present invention is used in marker pens, its pH is preferably 3 to 8, more preferably 4 to 7, and even more preferably 5 to 6. By keeping the pH within the above range, the aggregation or sedimentation of microcapsule pigments contained in the ink in the low-temperature region can be suppressed.

[0369] Additionally, the pH value was measured using a pH meter [manufactured by Aoya Discecek Co., Ltd., product name: IM-40S], with the ink placed in an environment of 20°C.

[0370] The ink used in the aforementioned writing instrument is contained within a writing instrument that has a pen tip and an ink filling mechanism.

[0371] As writing tools, there are various writing tools such as ballpoint pens, markers, fountain pens, ink pens, and calligraphy pens.

[0372] There are no particular restrictions on the pen tip as a writing tool; various types of pen tips can be used.

[0373] Among various pen tips, ballpoint pen tips can be categorized as follows: a pen tip in which a ball-holding part, formed by pressing and deforming a metal tube from the outside to the inside, holds a ball; a pen tip in which a ball-holding part, formed by cutting a metal material using a drill or similar tool, holds a ball; 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 in the above-mentioned pen tip is pushed forward by a spring body, etc.

[0374] In addition, there are no particular limitations on the materials used for the tip and ball of a ballpoint pen. Examples include superhard alloy, stainless steel, ruby, ceramic, resin, rubber, etc.

[0375] 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. In addition, surface treatments such as DLC coating can be applied to the beads.

[0376] As a marker tip, one end can be processed into a shape corresponding to the purpose, such as a cannonball shape, a rectangular shape, a wedge shape, or a shape that corresponds to the purpose, such as a resin-processed fiber body, a fused processed body of thermoplastic fiber, or a felt body. These are all commonly used porous components with interconnected pores in the range of approximately 30% to 70%, or extruded bodies of synthetic resin with multiple ink outlet holes extending along the axis.

[0377] Furthermore, the pen nib (pen body) in the form of a fountain pen can be, for example, a nib made by cutting a metal sheet such as stainless steel or gold alloy into a tapered shape at the front end and bending or bending it, or a nib made of resin molded into a pen tip shape. Additionally, a slit can be provided in the center of the pen body, or a ball can be provided at the front end.

[0378] As an ink filling mechanism, it can be, for example, an ink container or ink absorber that can directly fill writing instruments with ink.

[0379] The ink container can be made of a molded body or a metal tubular body, such as a thermoplastic resin made of polyethylene, polypropylene, polyethylene terephthalate, or nylon. In addition to directly connecting the pen tip, the ink container can also be connected to the pen tip via a connecting member.

[0380] The ink absorber is a fiber bundle formed by bundling curled fibers along its length, and is contained within a plastic cylinder, film, or other coating, with the porosity adjusted to approximately 40-90%.

[0381] When the writing instrument is filled with ink in a ballpoint pen, the structure and shape of the ballpoint pen itself are not particularly limited. For example, a ballpoint pen has an ink reservoir filled with shear-reducing ink inside the cylinder, the ink reservoir is connected to the pen tip with a ball attached to the front end, and a liquid plug for preventing backflow is tightly connected to the end face of the ink.

[0382] An ink backflow prevention composition is filled at the rear end of the ink filling the ink container.

[0383] The ink backflow prevention composition is made of non-volatile liquids and / or low-volatility liquids, such as petrolatum, spindle oil, castor oil, olive oil, refined mineral oil, liquid paraffin, polybutene, α-olefins, oligomers or co-oligomers of α-olefins, dimethyl silicone oil, methylphenyl silicone oil, amino-modified silicone oil, polyether-modified silicone oil, and fatty acid-modified silicone oil, etc.

[0384] The ink backflow prevention composition may be used in combination with one or more of the appropriate types.

[0385] In the ink backflow prevention composition, it is preferable to add a thickener to thicken it to a suitable viscosity.

[0386] Examples of thickeners include hydrophobic silica, methylated silica, aluminum silicate, swollen mica, hydrophobic bentonite, montmorillonite and other clay-based thickeners, magnesium stearate, calcium stearate, aluminum stearate and zinc stearate and other fatty acid metal soaps, tribenzylidene sorbitol, fatty acid amides, amide-modified polyethylene wax, hydrogenated castor oil, fatty acid dextrin and other dextrin compounds, and cellulose compounds.

[0387] Furthermore, the above-mentioned liquid ink backflow prevention composition and solid ink backflow prevention composition can also be used together.

[0388] Alternatively, the cylinder itself can be an ink filling mechanism, for example, ink can be directly filled into the cylinder, and a ballpoint pen tip can be installed at the front end of the cylinder.

[0389] A ballpoint pen with a pen tip and an ink filling mechanism can further have an ink supply mechanism for supplying ink from the ink filling mechanism to the pen tip.

[0390] There are no particular limitations on the ink supply mechanism. Examples include (1) a mechanism that supplies ink to the pen tip by having an ink induction core made of fiber bundles or the like as an ink flow regulator; (2) a mechanism that supplies ink to the pen tip by having a comb-shaped ink flow regulator; and (3) a mechanism that supplies ink to the pen tip by having multiple discs arranged side by side with comb-shaped gaps opened by the discs, a slit-shaped ink induction groove extending longitudinally along the axial direction of the discs, and a venting groove wider than the groove, and a pen refill formed by an ink induction core that guides ink from the ink filling mechanism to the pen tip along the axial direction.

[0391] There are no particular restrictions on the material used for the pen refill, as long as it is a synthetic resin that can be injection molded into a comb-like structure of multiple discs. Examples of synthetic resins include common polycarbonate, polypropylene, polyethylene, and acrylonitrile-butadiene-styrene copolymer (ABS resin). In particular, acrylonitrile-butadiene-styrene copolymer (ABS resin) is suitable for use considering its high moldability and ease of obtaining refill performance.

[0392] When a ballpoint pen has the aforementioned ink supply mechanism, in addition to the aforementioned ink container and cylinder, the aforementioned ink absorber can also be used as the ink filling mechanism.

[0393] Specifically, examples of ballpoint pens that contain writing ink include (1) a ballpoint pen in which the pen tip is connected directly or via a connecting member to an ink container, and a pen core formed by filling the pen with writing ink and filling the end face of the ink with an ink backflow prevention body is housed in a spool; (2) a ballpoint pen in which writing ink is directly filled in a spool and a mechanism is provided to supply ink to the pen tip by having a comb-shaped ink flow regulator or an ink induction core made of fiber bundles, etc., as an ink flow regulator; (3) a ballpoint pen in which writing ink is directly filled in a spool and a mechanism is provided to supply ink to the pen tip via the aforementioned pen core; and (4) a ballpoint pen in which an ink absorbent body made of fiber bundles impregnated with writing ink is housed in a spool and a mechanism is provided to supply ink to the pen tip by having an ink induction core made of fiber bundles, etc., as an ink flow regulator.

[0394] When writing instruments are filled with ink, the structure and shape of the marker itself are not particularly limited. For example, a marker may have an ink absorber that is filled with cohesive ink in the barrel and the ink absorber is connected to the marker tip.

[0395] In addition to directly connecting the pen tip to the ink absorber, the ink absorber can also be connected to the pen tip via a connecting component.

[0396] A marker pen equipped with a marker tip and an ink filling mechanism can further be equipped with an ink supply mechanism for supplying ink filled in the ink filling mechanism to the pen tip.

[0397] There are no particular limitations on the ink supply mechanism. For example, in addition to the ink supply mechanism of the ballpoint pen mentioned above, (4) can be cited as an example of an ink flow regulator that uses a valve mechanism to supply ink to the pen tip by opening the valve.

[0398] The valve mechanism can use the traditional pumping type, which opens by pressing the pen tip. It is suitable to set it to a spring pressure that opens by pen pressure.

[0399] When a marker pen has an ink supply mechanism, in addition to the ink absorber mentioned above, an ink container that can be directly filled with writing ink can also be used as the ink filling mechanism. Furthermore, the cylinder itself can be the ink filling mechanism, directly filling with writing ink.

[0400] Specifically, the structure of a marker pen for holding ink for writing instruments can be exemplified as follows: (1) A marker pen in which an ink-absorbing body made of a fiber bundle impregnated with ink for writing instruments is housed in a barrel, and a marker pen tip made of a fiber processed body or resin molded body with capillary gaps is connected to the barrel directly or via a connecting member by means of the ink-absorbing body and the pen tip; (2) A marker pen in which ink for writing instruments is directly filled into a barrel, and a mechanism is provided to supply ink to the pen tip by means of a comb-shaped ink flow regulator or an ink induction core made of fiber bundles, etc., as an ink flow regulator; (3) A marker pen in which... (4) A marker pen that directly fills the barrel with writing ink and has a mechanism for supplying ink to the pen tip via the aforementioned pen core; (5) A marker pen that has a pen tip and an ink reservoir via a valve mechanism that opens the valve by pressing the pen tip, and directly fills the ink reservoir with writing ink; (6) A marker pen in which a pen tip made of a fiber processing body or resin molding body with capillary gaps is connected to the pen tip directly or via a connecting member to an ink reservoir containing an ink reservoir made of a fiber bundle impregnated with writing ink, and a pen refill is housed in the barrel.

[0401] Furthermore, the aforementioned ballpoint pen or marker can also be made into a detachable structure, thus becoming an ink cartridge. In this case, it can be used by replacing the ink cartridge in the writing instrument with a new ink cartridge after the ink in the cartridge is used up.

[0402] As an ink cartridge, it can be a material that also serves as the shaft of the writing instrument by connecting it to the main body, or a material that is protected by the shaft (back shaft) after being connected to the main body of the writing instrument. Furthermore, in the latter case, it can be either a material in which the main body of the writing instrument and the ink cartridge are connected before use, or a material housed in the shaft in a non-connected state so that the user can connect the ink cartridge inside the shaft to begin use.

[0403] Furthermore, when directly filling writing instruments with ink in ballpoint pens or markers, to facilitate the redispersibility of the microcapsule pigments, it is preferable to incorporate a stirring element, such as a stirring ball, within the ink container or cylinder used to stir the ink. Examples of the stirring element's shape include spheres and rods. The material of the stirring element is not particularly limited and can include, for example, metal, ceramic, resin, or glass.

[0404] Furthermore, it is preferable to provide a cap that is installed to cover the writing tip (pen tip) in writing instruments such as ballpoint pens or markers, or to provide a telescopic mechanism that allows the writing tip to extend and retract from the main body (cylinder) of the writing instrument. This can prevent the writing tip from drying out and becoming unusable, or from being contaminated or damaged.

[0405] Any writing instrument equipped with a telescopic mechanism can be used as long as the writing tip is exposed to the outside air while being housed in a cylinder, and the writing tip protrudes from the cylinder opening through the operation of the telescopic mechanism. For example, the aforementioned ballpoint pen refill or marker refill can be manufactured with a structure in which the refill is housed in a cylinder and the writing tip protrudes from the cylinder opening through the operation of the telescopic mechanism, thereby creating a writing instrument equipped with a telescopic mechanism (telescopic writing instrument).

[0406] Furthermore, when the writing instrument is equipped with a telescopic mechanism, multiple ballpoint pen refills or marker refills can be housed inside the cylinder, creating a composite telescopic writing instrument (telescopic ballpoint pen or telescopic marker) in which the writing tip of any refill can extend or retract from the opening of the cylinder through the operation of the telescopic mechanism.

[0407] Examples of telescopic mechanisms include: (1) a side-sliding telescopic mechanism in which the writing tip extends from the front opening of the cylinder by sliding the operating part (pen clip) that can move forward and backward from the rear side wall of the cylinder; (2) a rear-end striking telescopic mechanism in which the writing tip extends from the front opening of the cylinder by pressing the operating part located at the rear end of the cylinder forward; (3) a side-striking telescopic mechanism in which the writing tip extends from the front opening of the cylinder by pressing the operating part that protrudes from the outside of the side wall of the cylinder inward; and (4) a rotating telescopic mechanism in which the writing tip extends from the front opening of the cylinder by rotating the operating part at the rear end of the cylinder.

[0408] Furthermore, the form of ballpoint pens and markers is not limited to the above-mentioned configuration. In addition to assembling pen tips of different shapes or pen heads that dispense ink of different shades, they can also be composite writing tools (double-ended, pen tip extended, etc.) that assemble pen tips of different shapes and dispense ink of different shades from each pen tip.

[0409] The ink used to write on the writing surface can be changed color by rubbing with a finger, heating or cooling.

[0410] Examples of heating tools include electric heating color-changing tools equipped with resistive heating elements such as PTC elements, heating color-changing tools filled with media such as warm water, heating color-changing tools using steam, lasers, etc., and the application of hair dryers. However, considering that the color can be changed by a simple method, friction components and friction bodies are preferred.

[0411] As a cooling tool, examples include electric thermochromic tools using Peltier elements, thermochromic tools filled with cooling media such as cold water or ice flakes, cold storage agents, cold storage warehouses, and freezers.

[0412] As a friction component and friction body, it is preferable to have an elasticity that generates moderate friction during rubbing, such as an elastomer or plastic foam, which can generate frictional heat. However, plastic molded bodies, stone, wood, metal, cloth, etc. can also be used.

[0413] In addition, although a regular eraser used to remove pencil marks can be used to erase the marks, the aforementioned friction member and friction body, which produce almost no shavings, are more suitable because they produce shavings during erasing.

[0414] Materials used as friction components and friction bodies include, for example, silicone resin and SEBS resin (styrene-ethylene-butadiene-styrene block copolymer). Silicone resin tends to adhere more easily to areas that have been wiped away by rubbing, and the ink is repelled upon repeated writing, making SEBS resin more suitable.

[0415] The aforementioned friction component or friction body can also be a component of any shape separate from the writing instrument, but by being incorporated into the writing instrument, it can achieve excellent portability. Furthermore, the writing instrument and the friction component or friction body of any shape separate from the writing instrument can be combined to obtain a writing instrument kit.

[0416] In the case of a writing instrument with a cap, there is no particular limitation on the location of the friction member or friction body. For example, the cap itself can be formed by the friction member, or the cylinder itself can be formed by the friction member, or the clip itself can be formed by the friction member if a 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 (part without a writing front end).

[0417] When the writing instrument is a telescopic writing instrument, there is no particular limitation on the location of the friction member or friction body. 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 if 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 without the writing front end) or at the striking part.

[0418] In addition, the above-mentioned ink can also be used as ink for stamps.

[0419] Water is used as the medium for ink used in stamps, but water-soluble organic solvents may also be used as needed.

[0420] When using microencapsulated pigments in stamp inks, glycerol or propylene glycol are preferred among water-soluble organic solvents.

[0421] The water-soluble organic solvent is preferably mixed in the range of 30-60% by mass, more preferably 30-55% by mass, and even more preferably 40-50% by mass relative to the total amount of ink. By keeping the mixing ratio of the water-soluble organic solvent within the above range, the ink will not dry out or absorb moisture, making it easy to obtain a bright print.

[0422] If the mixing ratio of water-soluble organic solvents exceeds 60% by mass, the hygroscopicity tends to increase, causing the ink to bleed or become uneven, making it difficult to obtain a clear and vivid print. On the other hand, if the mixing ratio is less than 30% by mass, the printing surface dries out, resulting in ink bleed and other issues, also making it difficult to obtain a clear and vivid print.

[0423] In addition, organic solvents can also be used as the aforementioned medium.

[0424] As organic solvents, examples include castor oil fatty acid alkyl esters, cellosol solvents, alkylene glycol solvents, ester solvents, hydrocarbon solvents, halogenated hydrocarbon solvents, alcohol solvents, ether solvents, ketone solvents, propionic acid solvents, highly polar solvents, or mixtures thereof.

[0425] Furthermore, a thickener can also be added to the ink for stamps. Among the thickeners, alkali-soluble acrylic emulsions are preferred.

[0426] When using an alkali-soluble acrylic emulsion as a thickener, the pH of the ink is preferably 6 to 11, more preferably 7 to 11, and even more preferably 7 to 10.

[0427] Furthermore, by adding adhesive resin to the ink for stamps, the adhesion of the imprint can be improved, or the viscosity of the ink can be adjusted.

[0428] Examples of adhesive resins include resin emulsions, alkali-soluble resins, and water-soluble resins.

[0429] In addition, depending on the requirements, wetting agents, resins, resin particles, pH adjusters, rust inhibitors, surfactants, humectants, defoamers, viscosity modifiers, preservatives, mildew inhibitors and other additives can also be mixed in.

[0430] In stamp inks, the reversible thermochromic microcapsule pigment is preferably blended at a ratio of 10-40% by mass, more preferably 10-35% by mass, and even more preferably 10-30% by mass relative to the total ink volume. If the blending ratio of the microcapsule pigment exceeds 40% by mass, the dispersion stability of the microcapsule pigment in the ink is prone to decrease. On the other hand, if the blending ratio is less than 10% by mass, the color concentration is prone to decrease.

[0431] The above-mentioned ink for stamps can be used as ink for ink pads or as ink for stamps with printing materials having continuous pores.

[0432] For example, by impregnating an ink pad with ink, an ink pad that supplies ink to the ink-producing surface of the stamp that comes into contact with it can be obtained. Alternatively, a stamp can be obtained by impregnating ink with a stamp material having continuously porous printing media.

[0433] The aforementioned stamp can leave an imprint on various surfaces. Furthermore, the imprint formed by the stamp with ink can be discolored by rubbing with a finger, or by applying the aforementioned heating or cooling tools. Considering that the discoloration can be achieved through a simple method, the aforementioned friction member and friction body are preferred as heating tools.

[0434] The aforementioned friction component or friction body can be any shape separate from the stamp, but by being mounted on the stamp, it achieves excellent portability. Furthermore, the stamp and the friction component or friction body, which is separate from the stamp and of any shape, can be combined to obtain a stamp kit.

[0435] When coating or printing reversible thermochromic liquid compositions, the material of the support is not particularly limited and is entirely applicable, such as paper, synthetic paper, fiber, fabric, synthetic leather, leather, plastic, glass, ceramic materials, metal, wood, stone, etc.

[0436] The shape of the support is not limited to a planar shape; it can be concave or convex.

[0437] By setting a reversible thermochromic layer containing a reversible thermochromic colorant on a support, a reversible thermochromic laminate (reversible thermochromic print) can be obtained.

[0438] When a non-thermochromic color layer (non-thermochromic image) is pre-formed on a support, the color layer or image can be made to appear and disappear intermittently through a reversible thermochromic layer by temperature changes, which can further diversify the appearance of the changes.

[0439] Furthermore, by melting and mixing the reversible thermochromic colorant into the excipient and molding it, a reversible thermochromic coating solid molded body can be made and used as a solid writing surface or solid cosmetic.

[0440] Examples of solid writing instruments include crayons, pencil leads, mechanical pencil leads, and solid gel markers.

[0441] As solid cosmetics, examples include foundation, eyeliner, eyebrow pencil, eyeshadow, and lipstick.

[0442] Examples of excipients used in solid writing include wax, gelling agents, and clay minerals.

[0443] In terms of excipients, it is preferable to contain at least one of polyolefin wax, sucrose fatty acid ester, or dextrin fatty acid ester, so as to facilitate the increase of ink density.

[0444] Furthermore, considering the excellent mechanical strength and thermochromic properties of solid writing instruments, as well as ease of handling during manufacturing, 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. Moreover, a substance with a number-average molecular weight (Mn) of 1,000 to 10,000 is preferred.

[0445] In addition, the mass-average molecular weight and number-average molecular weight are values ​​determined by gel permeation chromatography (GPC) based on polystyrene.

[0446] The excipient is preferably mixed in the range of 0.2% to 70% by mass relative to the total amount of solid writing material, more preferably in the range of 0.5% to 40% by mass. By mixing the excipient in the above range, it is easy to obtain the shape of the solid writing material, and it is easy to increase the ink density of the solid writing material.

[0447] If the mixing ratio of excipients exceeds 70% by mass, it is difficult to obtain sufficient writing concentration. On the other hand, if the mixing ratio is less than 0.2% by mass, it is difficult to obtain a shape suitable for use as a writing core.

[0448] In addition, by mixing fillers into solid writing instruments, the strength of the solid writing instruments can be improved and the writing feel can be adjusted.

[0449] Among the fillers mentioned above, talc or calcium carbonate are preferred due to their excellent formability and the fact that they are less likely to impair thermochromic properties when microencapsulated pigments are used.

[0450] The filler is preferably blended in the range of 10% to 65% by mass relative to the total amount of solid writing material. If the blending ratio of filler exceeds 65% by mass, the color development and writing feel are prone to decrease. On the other hand, if the blending ratio is less than 10% by mass, the strength of the solid writing material is prone to decrease.

[0451] Furthermore, the strength of the solid writing material can be increased by mixing it with an adhesive resin.

[0452] In the adhesive resin, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, and polyvinyl alcohol are preferred. By using these resins in combination with polyester polyols, molding stability can be improved.

[0453] The adhesive resin is preferably mixed in the range of 0.5 to 5% by mass relative to the total amount of solid writing material.

[0454] Furthermore, by incorporating hindered amine compounds into the solid writing material, the residual image at the erased area on the written surface becomes difficult to discern. Therefore, the aesthetics of the written surface are not compromised, and rewriteability is satisfactory, thus improving commercial viability.

[0455] In addition, depending on the requirements, viscosity modifiers, mildew inhibitors, preservatives, antibacterial agents, UV inhibitors, antioxidants, lubricants, fragrances and other additives can also be mixed in.

[0456] Solid writing objects can be used alone as writing objects, or they can be made into a core-sheath structure (double core) with an outer shell covering their outer periphery.

[0457] The outer casing may also contain additives such as non-thermal colorants, mildew inhibitors, preservatives, antibacterial agents, UV absorbers, antioxidants, lubricants, and fragrances, depending on the requirements.

[0458] The aforementioned solid writing material can write on various writing surfaces. Furthermore, since a reversible thermochromic colorant is used, the handwriting obtained on the writing surface can change color by rubbing with a finger, applying the aforementioned heating tool, or using a hot / cold tool. Considering that it can be changed color by a simple method, the aforementioned friction member and friction body are preferred as heating tools.

[0459] The aforementioned friction member or friction body can be any shape of component separate from the solid writing tablet or the outer casing of a solid writing tool that houses the solid writing tablet. However, by providing it to the outer casing of the solid writing tablet or the solid writing tool that houses the solid writing tablet, portability can be greatly improved. Specifically, examples include the form in which a friction member is provided in the shape of a pencil or crayon with an outer casing made of wood, paper, etc. Furthermore, a solid writing tablet kit can be obtained by combining the solid writing tablet and the friction member or friction body of any shape separate from the solid writing tablet.

[0460] Furthermore, reversible thermochromic colorants can be melt-blended into thermoplastic resins, thermosetting resins, waxes, etc., to form granules, powders, or pastes, and used as resin compositions for reversible thermochromic molding.

[0461] The above-mentioned reversible thermochromic molding resin composition can be used to obtain molded bodies of any shape, such as three-dimensional objects, films, sheets, plates, filaments, rods, tubes, etc., through common injection molding, extrusion molding, blow molding, or casting molding.

[0462] In addition, colorants and powder coatings can also be obtained by melt blending into thermoplastic resins.

[0463] In addition, by mixing general dyes and pigments and other non-thermochromic colorants into the above-mentioned reversible thermochromic liquid composition, coating solid molded body and molding resin composition, a color-changing behavior from colored (1) to colored (2) is exhibited.

[0464] By layering light stabilizers and / or transparent metallic pigments onto the molded or laminated body described above, lightfastness can also be improved, or a top coating can be applied to improve durability.

[0465] Examples of light stabilizers include ultraviolet absorbers, antioxidants, singlet oxygen quenchers, superoxide anion quenchers, and ozone quenchers.

[0466] Examples of transparent metallic pigments include those obtained by coating the surface of natural mica, synthetic mica, glass sheets, alumina, or transparent films with metal oxides such as titanium dioxide.

[0467] Specifically, the following substances can be cited as examples of articles that use a reversible thermochromic composition and microcapsule pigments or resin particles containing the reversible thermochromic composition.

[0468] (1) Toys

[0469] Dolls and animal figurines, doll and animal figurine hair, doll houses and furniture, clothing, hats, handbags, shoes and other doll accessories, decorative toys, cloth dolls, drawing toys, toy books, puzzles and other educational toys, building blocks, jigsaw puzzles, clay toys, mobile toys, spinning tops, kites, musical instrument toys, cooking toys, gun toys, capture toys, background toys, toys that imitate vehicles, animals, plants, buildings, food, etc.

[0470] (2) Clothing

[0471] Clothing such as T-shirts, training clothes, women's shirts, women's dresses, swimwear, raincoats, ski suits, shoes and shoelaces, cloth personal items such as handkerchiefs, towels, and cloth bags, gloves, ties, hats, bow ties, and scarves.

[0472] (3) Interior decorations

[0473] Curtains, curtain cords, tablecloths, bedding, cushions, carpets, travel blankets, chair covers, chairs, mats, decorative frames, artificial flowers, photo frames, etc.

[0474] (4) Furniture

[0475] Bedding such as quilts, pillows, and mattresses; lighting fixtures; and air conditioning appliances.

[0476] (5) Decorations

[0477] Rings, bracelets, headdresses, earrings, hair clips, false nails, ribbons, bow ties, watches, glasses, etc.

[0478] (6) Stationery

[0479] Writing instruments, stamping tools, erasers, writing pads, rulers, journals, adhesive tape, etc.

[0480] (7) Daily necessities

[0481] Cosmetics such as lipstick, eyeshadow, foundation, eyeliner, eyebrow pencil, nail polish, hair dye, false nails, and nail polish paint; toothbrushes, etc.

[0482] (8) Kitchenware

[0483] Cups, plates, chopsticks, spoons, forks, pots, frying pans, etc.

[0484] (9) Other

[0485] Calendars, labels, cards, record materials, various printed materials for anti-counterfeiting purposes, brochures and other books, handbags, packaging containers, embroidery thread, sports equipment, fishing gear, coasters, musical instruments, hand warmers, cold storage agents, wallets and other bags, umbrellas, vehicles, buildings, temperature indicators, teaching aids, etc.

[0486] Example

[0487] The following examples are shown. Additionally, unless otherwise specified, "parts" and "%" in the examples refer to "parts by mass" and "% by mass," respectively.

[0488] <Example 101>

[0489] Preparation of reversible thermochromic microcapsule pigments

[0490] Four parts of 2-anilino-3-methyl-6-(N-ethyl-N-p-tolylamino)fluorane (as component (a), eight parts of 1,1-bis(4-hydroxyphenyl)-2-ethylhexane (B1-1) (as component (b), and 25 parts of betaine alcohol (C-1) and stearyl stearate (C-2) (as component (c)) were mixed and dissolved by heating to obtain a reversible thermochromic composition that changes from black to colorless.

[0491] The reversible thermochromic composition was added to a mixed solution consisting of 35 parts of aromatic isocyanate prepolymer and 40 parts of cosolvent, which served as the wall film material. The mixture was then emulsified and dispersed in an 8% polyvinyl alcohol aqueous solution. After continuous stirring while heating, 2.5 parts of water-soluble aliphatic modified amine were added, and the mixture was stirred further to prepare a microcapsule dispersion. Microcapsule pigments with an average particle size of 2.0 μm were obtained from the above microcapsule dispersion by centrifugation.

[0492] <Examples 102-110 and Comparative Examples 101, 102>

[0493] By changing the types and amounts of components (b) and (c) as described in Table 1, and otherwise operating in the same manner as in Example 101, a microcapsule pigment that changed from black to colorless was obtained.

[0494] The values ​​for components (b) and (c) in the table represent "parts by mass", and the values ​​for concentration retention rate represent "%".

[0495] [Table 1]

[0496] Table 1

[0497]

[0498] Components (b) and (c) in the table are the compounds shown below.

[0499] B1-1 1,1-Bis(4-hydroxyphenyl)-2-ethylhexane

[0500] B1-2 1,1-Bis(4-hydroxyphenyl)-2-methylpropane

[0501] B1-3 1,1-bis(4-hydroxyphenyl)n-decane

[0502] B1-4-1-Phenylacetylene-1,1-bis(4-hydroxyphenyl)ethane

[0503] B2-1 4,4'-[1-{4-〔1-(4-hydroxyphenyl)-1-methylethyl〕phenyl}ethylidene]bisphenol

[0504] B3-1 2,2-bis(4-hydroxyphenyl)hexafluoropropane

[0505] B4-1 4-Benzyloxy-4'-hydroxydiphenyl sulfone

[0506] B4-2 2,4'-Dihydroxydiphenylsulfone

[0507] B5-1 2,4-Dihydroxy-4'-tert-butylbenzophenone

[0508] C-1 Sagerol

[0509] C-2 stearyl stearate

[0510] C-3 decanoic acid 4-benzyloxyphenyl ethyl ester

[0511] [Color Change Temperature Measurement]

[0512] A reversible thermochromic ink was prepared by mixing 40 parts of each microcapsule pigment obtained in Examples 101-110 and Comparative Examples 101 and 102, 52 parts of ethylene-vinyl acetate copolymer resin emulsion, 5 parts of thickener, and 3 parts of leveling agent. A full-page pattern was screen-printed on high-grade paper using the above ink to obtain a sample for color temperature measurement. Each sample for color temperature measurement was placed in the measuring section of a colorimeter (manufactured by Tokyo Denshoku Co., Ltd., product name: TC-3600), and the sample was heated and cooled at a rate of 2°C / min. The lightness value was measured as the color concentration at each temperature, and a color concentration-temperature curve was prepared. The complete color development temperature t1, color development onset temperature t2, color fading onset temperature t3, complete color fading temperature t4, and ΔH (hysteresis width: (the temperature between t3 and t4) - (the temperature between t1 and t2)) were determined from the color concentration-temperature curve. The results are shown in Table 2 below.

[0513] The values ​​in the table represent "℃".

[0514] [Table 2]

[0515] Table 2

[0516]

[0517] [Lightfastness Evaluation]

[0518] A reversible thermochromic ink was prepared by mixing 40 parts of each microcapsule pigment from Examples 101-110 and Comparative Examples 101 and 102, 52 parts of ethylene-vinyl acetate copolymer resin emulsion, 5 parts of thickener, and 3 parts of leveling agent. A test sample was obtained by screen printing a full-page pattern onto high-grade paper using the ink.

[0519] After the above-mentioned test samples were cooled to below t1 to become fully colored, they were placed in the measuring section of a fluorescence spectrophotometer [manufactured by Conicaminodesa Corporation, product name: FD-7 type], and the absolute concentration of the fully colored state (hereinafter referred to as "initial concentration") was measured.

[0520] Next, the samples for which the concentration was determined were subjected to xenon lightfastness testing at a temperature not exceeding t3 using a xenon lightfastness testing machine [manufactured by Suga Testing Machine Co., Ltd., product name: Table Sun XT75] at 170w / m 2 The irradiance was continuously applied for 10 hours.

[0521] After the light-irradiated samples were taken out and cooled to below t1 to become fully colored, the samples were placed in the measuring section of the fluorescence spectrophotometer and the absolute concentration of the fully colored state after light irradiation was measured (hereinafter referred to as "concentration after light irradiation").

[0522] The concentration retention rate [(concentration after light irradiation) / (initial concentration) × 100] was calculated from the initial concentration value and the concentration value after light irradiation. Furthermore, a higher concentration retention rate indicates better lightfastness. The results are shown in Table 1.

[0523] <Examples 201-207>

[0524] By changing the types and amounts of components (b) and (c) as described in Table 3, and otherwise operating in the same manner as in Example 101, a microcapsule pigment that changed from black to colorless was obtained.

[0525] <Example 208>

[0526] Preparation of reversible thermochromic microcapsule pigments

[0527] Six parts of 2-anilino-3-methyl-6-(N-ethyl-N-p-tolylamino)fluorane (as component (a)), 10 parts of 1,1-bis(4-hydroxyphenyl)-2-ethylhexane (B1-1) (as component (b)), 5 parts of 4,4'-[1-{4-〔1-(4-hydroxyphenyl)-1-methylethyl〕phenyl}ethylidene]bisphenol (B2-1) (as component (b)), 50 parts of 4-benzyloxyphenyl ethyl decanoate (C-3) (as component (c)), and 1 part of 2-(3,5-di-tert-pentyl-2-hydroxyphenyl)-2H-benzotriazole (as a light stabilizer) and 0.2 parts of bis(1,2,2,6,6-pentamethyl-4-piperidinyl) ester of 2-(3,5-di-tert-butyl-4-hydroxybenzyl)-2-n-butylmalonate (as a light stabilizer) were mixed and dissolved by heating to obtain a reversible thermochromic composition that changes from black to colorless. Using the reversible thermochromic composition, microencapsulated pigments were obtained in the same manner as in Example 101.

[0528] The values ​​for components (b) and (c) in the table represent "parts by mass", and the values ​​for concentration retention rate represent "%".

[0529] [Table 3]

[0530] Table 3

[0531]

[0532] Components (b) and (c) in the table are the compounds shown below.

[0533] B1-1, B2-1, and B3-1 are the same as above.

[0534] B4-3 4-Isopropoxy-4'-hydroxydiphenyl sulfone

[0535] C-1, C-2, and C-3 are the same as above.

[0536] C-4 4-Biphenylacetic acid cyclohexyl methyl ester

[0537] [Color Change Temperature Measurement]

[0538] A reversible thermochromic ink was prepared by mixing 40 parts of each of the microcapsule pigments obtained in Examples 201-208, 52 parts of ethylene-vinyl acetate copolymer resin emulsion, 5 parts of thickener, and 3 parts of leveling agent. A sample for measuring the color-changing temperature was obtained by screen printing a full-page pattern on high-grade paper using the above ink.

[0539] For the samples used in the color change temperature determination, t1, t2, t3, t4, and ΔH were calculated using the same determination method as described above. The results are shown in Table 4 below.

[0540] The values ​​in the table represent "℃".

[0541] [Table 4]

[0542] Table 4

[0543]

[0544] [Concentration Measurement]

[0545] A reversible thermochromic ink was prepared by mixing 40 parts of each of the microcapsule pigments obtained in Examples 102, 201-208, 52 parts of ethylene-vinyl acetate copolymer resin emulsion, 5 parts of thickener, and 3 parts of leveling agent. A sample for concentration determination was obtained by screen printing a full-page pattern onto high-grade paper using the ink.

[0546] The concentration test samples of Examples 102, 201 to 208, which were cooled to below t1 and became fully colored, were placed in the measuring section of a fluorescence spectrophotometer [manufactured by Conicaminodes Co., Ltd., product name: FD-7 type], and the absolute concentration of the colored state (hereinafter referred to as "color concentration") was measured.

[0547] Furthermore, samples from Examples 102, 201-208, which were heated to above t4 and became completely achromatic, were placed in the measurement section of the fluorescence spectrophotometer described above, and the absolute concentration of the achromatic state (hereinafter referred to as "achromatic concentration") was measured. The results are shown in Table 3.

[0548] [Lightfastness Evaluation]

[0549] A reversible thermochromic ink was prepared by mixing 40 parts of each of the microcapsule pigments from Examples 201 to 208, 52 parts of ethylene-vinyl acetate copolymer resin emulsion, 5 parts of thickener, and 3 parts of leveling agent. A test sample was obtained by screen printing a full-page pattern onto high-grade paper using the ink.

[0550] For each of the above-mentioned test samples, the concentration retention rate was determined using the same test method as described above. The results are shown in Table 3.

[0551] Application Example 1

[0552] Fabrication of reversible thermochromic plugs

[0553] 2.5 parts of the microcapsule pigment of Example 102 (pre-cooled to below -20°C to make it black) and 1.5 parts of a pink general pigment were mixed in an oily color carrier consisting 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 viscosity modifier to prepare a reversible thermochromic liquid composition for use as a spray coating.

[0554] The plug portion (white) of the household electrical wire, which serves as the support, is spray-coated with the aforementioned paint and dried to create a reversible thermochromic layer, thus producing a reversible thermochromic plug.

[0555] If a reversible thermochromic plug is black at room temperature (25°C) and turns pink at temperatures above 58°C, the pink color change can be maintained as long as it is not cooled to below -20°C. Therefore, the temperature history of the plug reaching a high temperature range of 58°C or above can be visually confirmed when it becomes overheated.

[0556] Application Example 2

[0557] Fabrication of reversible thermochromic recording materials (cards for information display)

[0558] 40 parts of the microcapsule pigment of Example 106 (pre-cooled to below -20°C to make it black) were uniformly mixed in an aqueous color carrier consisting of 50 parts of urethane resin emulsion, 3 parts of leveling agent and 1 part of thickener to prepare a reversible thermochromic liquid composition for use as printing ink.

[0559] On the surface of a transparent polyester film (25 μm thick) with an adhesive layer on the back, serving as a support, a transparent tackifying coating formed of urethane resin and isocyanate-based curing agent is applied. On top of this coating, the aforementioned printing ink is screen-printed onto the entire surface and then dried and cured to form a reversible thermochromic layer. Further, a transparent protective layer comprising epoxy acrylate oligomers, polyester acrylate oligomers, and acrylate monomers is applied on top of this layer and irradiated with ultraviolet light to polymerize it, thus producing a reversible thermochromic recording material. This recording material is then adhered to a white polyester film (188 μm thick) serving as a substrate, and the film is used as an information display card.

[0560] After temporarily cooling the reversible thermochromic recording material to below -20°C, causing the reversible thermochromic layer to fully turn black, text information was printed using a thermal printer with a hot head.

[0561] The aforementioned recording material clearly displays white text information (perforated text) against a black background. The white text information is recognizable as long as the temperature is maintained between -20°C and 60°C. Furthermore, if the recording material is cooled to below -20°C, causing the reversible thermochromic layer to fully turn black, the white perforated text becomes illegible. The recording material can be reused multiple times by using a thermal printer in this state to create white perforated text on the reversible thermochromic layer.

[0562] Application Example 3

[0563] Production of reversible thermochromic printed materials (reversible thermochromic T-shirts)

[0564] 30 parts of the microcapsule pigment of Example 108 (pre-cooled to below -20°C to make it black) were uniformly mixed in an aqueous color carrier consisting of 60 parts of acrylic emulsion (45% solids), 0.2 parts of defoamer, 1 part of viscosity modifier, and 8.8 parts of water to prepare a reversible thermochromic liquid composition for use as printing ink.

[0565] On a white cotton T-shirt, which serves as a support, multiple star patterns are printed using the aforementioned printing ink through a 100-mesh screen. The ink is then dried and cured to create a reversible thermochromic layer, thus producing a reversible thermochromic printed material (reversible thermochromic T-shirt).

[0566] At room temperature (25°C), multiple black star patterns are visible on the T-shirt surface, remaining unchanged at body temperature and ambient temperature. However, if heated above 61°C, the areas with printed star patterns become colorless, and the black star patterns become undetectable. Furthermore, if cooled below -20°C, the black star patterns become visible again. This process can be repeated.

[0567] Furthermore, by heating a portion of the star pattern on the T-shirt surface with an iron or similar means, the color can be removed, creating a pattern where only a random star pattern is removed, allowing for arbitrary changes to the T-shirt's design. Additionally, the color-changing state can be maintained at room temperature (25°C). This can be achieved by heating the entire T-shirt to above 61°C to remove the entire star pattern area, then cooling it to below -20°C to allow the star pattern to re-color.

[0568] Application Example 4

[0569] The production of doll toys using hair made of reversible thermochromic composite fibers

[0570] Five parts of the microcapsule pigment from Example 110, one part of dispersant, nylon 12 (94 parts) with a melting point of 180°C, and 0.1 parts of a general pink pigment were melt-mixed using an extruder at 200°C to prepare a reversible thermochromic molding resin composition in granular form for the core.

[0571] The aforementioned particles are fed to an extrusion molding machine for core forming, and nylon 12 natural particles are fed to an extrusion molding machine for sheath forming. Using a composite fiber spinning device, the fibers are spun at 200°C from an 18-hole discharge port with a core-to-sheath volume ratio of 6:4, to produce a reversible thermochromic composite fiber with an outer diameter of 90 μm composed of 18 monofilaments.

[0572] If the reversible thermochromic composite fiber is temporarily cooled to below -20°C to allow the microcapsule pigments to fully develop their color, the reversible thermochromic composite fiber will appear black. The reversible thermochromic composite fiber is then implanted into the head of a doll using conventional methods to create a doll toy with hair made from the reversible thermochromic composite fiber.

[0573] The fur of the aforementioned doll remains unchanged at body temperature and ambient temperature, but turns from black to pink when heated above 60°C. Furthermore, it reverts to black when cooled below -20°C. This process can be repeated.

[0574] Furthermore, by heating a portion of the hair using a dryer or similar means to decolorize it, a pattern is created where only random areas are decolorized, allowing for arbitrary changes in hair color. Moreover, this color-changing state can be maintained at room temperature (25°C), and the hair can be heated to above 60°C to decolorize it, then cooled to below -20°C to recolor it back to black.

[0575] Application Example 5

[0576] Production of reversible thermochromic writing instruments (reversible thermochromic ballpoint pens)

[0577] 25 parts of the microcapsule pigment from Example 202 (pre-cooled to below -20°C to achieve a black color), 0.3 parts of shear-thickening agent (xanthan gum), 10 parts of urea, 10 parts of glycerin, 0.5 parts of nonionic permeability enhancer (manufactured by Sunopco Co., Ltd., product name: Nopoko SW-WET-366), and 0.5 parts of modified silicone defoamer (manufactured by Sunopco Co., Ltd., product name: Nopoko SW-WET-366) were prepared. A reversible thermochromic liquid composition for use as a writing instrument is prepared by mixing 0.1 parts of [Pico8034], 0.5 parts of phosphate ester surfactant [manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd., product name: Premium AL], 0.5 parts of pH adjuster (triethanolamine), 0.2 parts of antifungal agent [manufactured by Lonzajapan Co., Ltd., product name: Prokisell XL-2], and 52.9 parts of water.

[0578] The writing instrument described above is filled with ink through a polypropylene tube, and then connected to the tip of a ballpoint pen, which holds a 0.5mm diameter stainless steel ball, via a resin retainer. Next, a viscoelastic ink backflow preventer (liquid plug) made primarily of polybutene is filled into the rear of the ink tube, further fitting the plug into the rear of the tube. The front and rear shaft cylinders are assembled, a cap is fitted, and the pen is degassed by centrifugation to produce a ballpoint pen. Additionally, SEBS resin, serving as a friction component, is installed at the rear end of the rear shaft cylinder.

[0579] Writing on paper with the ballpoint pen produces black text (handwriting). The handwriting remains black at room temperature (25°C). If the text is rubbed with a friction component, it fades to colorless. This state can be maintained as long as the temperature does not drop below -20°C. Furthermore, if the paper is placed in a freezer and cooled to below -20°C, the text will again turn black, and this color-changing behavior can be repeated.

[0580] Application Example 6

[0581] Production of reversible thermochromic writing instruments (reversible thermochromic markers)

[0582] 20 parts of the microcapsule pigment from Example 203 (pre-cooled to below -20°C to achieve a black color) were mixed with 0.4 parts of a polymeric coagulant (hydroxyethyl cellulose) [Dookemical Japan Co., Ltd., product name: CELLOSIZE EP-09], 0.4 parts of an acrylic polymeric dispersant [Nippon Rubrizoel Co., Ltd., product name: Solspace 43000], 0.2 parts of a preservative (sodium 2-pyridinethiol 1-oxide) [Lonzajapan Co., Ltd., product name: Sojamoyamajin], and 0.2 parts of a preservative (3-iodo-2-propynyl N-butylcarbamate) [Lonzajapan]. A reversible thermochromic liquid composition for use as a writing instrument is prepared by mixing 0.2 parts of an aqueous colorant consisting of glycerin, 18 parts of defoamer, 0.2 parts of pH adjuster (10% diluted phosphoric acid solution), 8 parts of specific gravity adjuster (sodium polytungstate) (manufactured by SOMETU Co., Ltd., product name: SPT), and 46.6 parts of water.

[0583] The aforementioned writing instrument is impregnated with ink in an ink absorbent body made by coating a polyester strip with a synthetic resin film. This absorbent body is housed within a cylindrical shell formed of polypropylene resin. A resin-processed pen body (bullet type) with multiple axially extending ink outlet holes is assembled in a connected state at the front end of the cylindrical shell via a retainer. A cap is then attached to produce a marker pen. SEBS resin, serving as a friction element, is installed on the top of the cap.

[0584] Writing on paper with the aforementioned marker creates black text (handwriting). The handwriting remains black at room temperature (25°C). If the text is rubbed with a friction component, it fades and becomes colorless. This state can be maintained as long as the temperature does not drop below -20°C. Furthermore, if the paper is placed in a freezer and cooled to below -20°C, the text will again turn black, and this color-changing behavior can be repeated.

[0585] Application Example 7

[0586] Production of reversible thermochromic printed materials

[0587] 30 parts of the microcapsule pigment of Example 204 (pre-cooled to below -20°C to make it black), 5 parts of red dye, and 65 parts of linseed oil-based offset ink carrier were mixed to prepare a reversible thermochromic liquid composition for offset printing ink.

[0588] Offset printing is performed on both sides of high-grade paper, which serves as the printing medium, using the aforementioned offset printing ink. The ink is then dried and cured to form a date (thermochromic image). It should be noted that the thermochromic images on the front and back sides are not overlapped. Next, offset printing is performed using a non-thermochromic black offset printing ink, and the ink is dried and cured to form a border (non-thermochromic image), thus producing a reversible thermochromic printed material.

[0589] The aforementioned reversible thermochromic printed material initially appears as a planner with black dates, but it can be changed to red by frictional heat generated from rubbing the thermochromic image on any part of the surface using a friction member. This reddened state is maintained at room temperature (25°C), making it useful for managing schedules on rest days. Furthermore, the date on the reverse side, where the reddened area is located, changes color because it does not transfer heat when the thermochromic image on the surface changes, allowing for accurate schedule management.

[0590] Application Example 8

[0591] Production of reversible thermochromic stamps

[0592] 20 parts of the microcapsule pigment from Example 205 (pre-cooled to below -20°C to achieve a black color), 50 parts of glycerin, 1.5 parts of an alkali-soluble acrylic emulsion [Roam And Heart Japan Co., Ltd., product name: Primal DR73], 0.9 parts of triethanolamine, 10 parts of a 50% aqueous solution of polyvinylpyrrolidone, 0.2 parts of an organosilicon defoamer, 0.5 parts of a penetrating leveling agent, 0.2 parts of a preservative, and 16.7 parts of water were mixed to prepare a reversible thermochromic liquid composition for use as ink for stamps.

[0593] The above-mentioned stamp is made by impregnating a printing material with continuous pores with ink, adhering it to the stamp substrate with the printing surface of the printing material exposed, and then putting on a cap. In addition, SEBS resin as a friction member is installed at the rear end of the stamp substrate.

[0594] If the above-mentioned stamp is repeatedly pressed onto the stamped surface (paper), the ink will flow smoothly from the printing material to the stamped surface without bleed-through, forming a clear and continuous imprint. The imprint is black at room temperature (25°C). If rubbed with a friction component, the imprint will fade and become colorless, a state that can be maintained as long as it is not cooled below -20°C. Furthermore, if the paper is placed in a freezer and cooled below -20°C, the imprint will again turn black, and this color change can be repeated.

[0595] Application Example 9

[0596] Production of reversible thermochromic writing instruments (reversible thermochromic markers)

[0597] 23 parts of the microcapsule pigment from Example 206 (pre-cooled to below -20°C to achieve a black color) were mixed with 0.4 parts of a polymeric coagulant (hydroxyethyl cellulose) [Dookemical Japan Co., Ltd., product name: CELLOSIZE WP-09], 0.4 parts of an acrylic polymeric dispersant [Japan Loobrezool Co., Ltd., product name: Solspass 43000], 0.2 parts of a preservative (2-pyridinethiol 1-oxide sodium) [Lonzajapan Co., Ltd., product name: Sojamoomagin], and 0.2 parts of a preservative (3-iodo-2-propynyl N-butyrate). A reversible thermochromic liquid composition for use as a writing instrument is prepared by mixing 0.2 parts of urethane (manufactured by Lonzajapan Co., Ltd., product name: Glycasil 2000), 30 parts of glycerin, 0.01 parts of defoamer, 0.03 parts of pH adjuster (10% diluted phosphoric acid solution), and 45.76 parts of water with an aqueous carrier.

[0598] The aforementioned writing instrument is impregnated with ink in an ink absorbent body made by coating a polyester strip with a synthetic resin film. This absorbent body is then housed within a barrel formed of polypropylene resin. A resin-processed polyester fiber pen body (wedge-shaped) is assembled at the front end of the barrel via a resin retainer, and a cap is attached to create a marker pen. Additionally, SEBS resin, serving as a friction component, is installed at the rear end of the barrel.

[0599] Writing on paper with the aforementioned marker creates black text (handwriting). The handwriting remains black at room temperature (25°C). If the text is rubbed with a friction component, it fades and becomes colorless. This state can be maintained as long as the temperature does not drop below -20°C. Furthermore, if the paper is placed in a freezer and cooled to below -20°C, the text will again turn black, and this color-changing behavior can be repeated.

[0600] Application Example 10

[0601] Fabrication of reversible thermochromic solid writing instruments

[0602] The following ingredients were mixed in a kneader: 40 parts of the microcapsule pigment from Example 207, 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 Industry Co., Ltd., product name: Sunwx 131-P (softening point 110°C, penetration 3.5)], 2 parts of styrene-acrylic acid copolymer, 2 parts of polyvinyl alcohol, and 1 part of hindered amine light stabilizer to prepare a core compound. 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 mixed in a kneader to prepare an outer shell compound. Using the aforementioned core compound as the core, a shell compound is wound around its outer circumference and compressed using a press to form a core with an outer diameter of φ3mm and a length of 60mm (the core is φ2mm, and the shell coating thickness is 0.5mm), thus producing a core-sheath structure solid writing device. Furthermore, the above dimensions are set values. After compression molding, the device is cooled to -20°C and then restored to room temperature to produce the solid writing device.

[0603] A pencil is obtained by housing the aforementioned solid writing material within a circular outer shaft (wooden shaft). Further, a cylindrical friction element made of SEBS resin is attached to the rear end of the pencil via a metal connecting member, creating a solid writing tool with a friction element (a pencil with a friction element). Writing on paper using this solid writing tool produces black text (handwriting). The handwriting remains black at room temperature (25°C). If the text is rubbed with the friction element, it fades to colorless, a state that can be maintained as long as the temperature does not drop below -20°C. Furthermore, if the paper is placed in a freezer and cooled to below -20°C, the text reverts to its original black color, and this color-changing behavior can be repeatedly reproduced.

[0604] Application Example 11

[0605] Production of reversible thermochromic writing instruments (reversible thermochromic ballpoint pens)

[0606] 25 parts of the microcapsule pigment from Example 208 (pre-cooled to below -20°C to achieve a black color), 0.3 parts of shear-thickening agent (xanthan gum), 10 parts of urea, 10 parts of glycerin, 0.5 parts of nonionic permeability enhancer (manufactured by Sannopoko Co., Ltd., product name: Nopoko SW-WET-366), and 0.5 parts of modified silicone defoamer (manufactured by Sannopoko Co., Ltd., product name: Nopoko SW-WET-366) were prepared. A reversible thermochromic liquid composition for use as a writing instrument is prepared by mixing 0.1 parts of [Pico8034], 0.5 parts of phosphate ester surfactant [manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd., product name: Premium AL], 0.5 parts of pH adjuster (triethanolamine), 0.2 parts of antifungal agent [manufactured by Lonzajapan Co., Ltd., product name: Prokisell XL-2], and 52.9 parts of water.

[0607] The writing instrument described above is filled with ink using an ink reservoir made of polypropylene. This reservoir is then connected to the tip of a ballpoint pen, which holds a 0.5mm diameter ultra-hard ball. Next, a viscoelastic ink backflow preventer (liquid stopper) made primarily of polybutene is filled into the rear of the ink reservoir to create a ballpoint pen refill. This refill is then inserted into the cylinder to obtain a ballpoint pen (retractable ballpoint pen).

[0608] The aforementioned ballpoint pen has a structure in which the pen tip, which is located within the ballpoint pen refill, is housed within the spool while exposed to external air. The pen tip protrudes from the front opening of the spool through the operation of a clip-shaped telescopic mechanism (sliding mechanism) located on the rear side wall of the spool. Furthermore, SEBS resin, serving as a friction component, is installed at the rear end of the spool.

[0609] Writing on paper with the ballpoint pen produces black text (handwriting). The handwriting remains black at room temperature (25°C). If the text is rubbed with a friction component, it fades to colorless. This state can be maintained as long as the temperature does not drop below -20°C. Furthermore, if the paper is placed in a freezer and cooled to below -20°C, the text will again turn black, and this color-changing behavior can be repeated.

[0610] Explanation of symbols

[0611] T1 complete color development temperature

[0612] t2 color development start temperature

[0613] T3 decolorization start temperature

[0614] T4 complete decolorization temperature

[0615] T1 complete decolorization temperature

[0616] T2 decolorization start temperature

[0617] T3 color development start temperature

[0618] T4 Full Color Rendering Temperature

[0619] ΔH is the hysteresis width.

Claims

1. A reversible thermochromic microcapsule pigment, comprising a reversible thermochromic composition, said reversible thermochromic composition comprising: (a) a compound of formula (A) as an electron-donating chromogenic organic compound; (b) a compound of formula (B1), (B2), (B3), (B4), or (B5) as an electron-accepting compound; and (c) a reaction medium that causes the electron transfer reaction of component (a) and component (b) to occur reversibly in a specific temperature region, wherein component (c) is at least one compound selected from alcohols having 10 or more carbon atoms, esters having 10 or more carbon atoms, ketones having 10 or more carbon atoms, ethers having 10 or more carbon atoms, and acid amides having 10 or more carbon atoms. In the formula, R a1 For ethyl, R a2 It is a methyl group, p = 1, q = 0. In the formula, R b1 R is a hydrogen atom, a straight-chain or branched alkyl group having 1 to 17 carbon atoms, or an aryl group having 6 to 10 carbon atoms. b2 It is a straight-chain or branched alkyl group having 1 to 17 carbon atoms, or an aryl group having 6 to 10 carbon atoms, wherein... The methylene group (-CH2-) in the alkyl group can be replaced by an oxygen group (-O-), a carbonyl group (-CO-), or an imino group (-NH-), wherein R b1 With R b2 They can form a ring together, R b3 and R b4 Each of the following is independently a straight-chain or branched alkyl group having 1 to 4 carbon atoms, an alkenyl group having 2 to 4 carbon atoms, an aryl group having 6 to 10 carbon atoms, or a halogen atom, which can be substituted by a fluorine atom or a hydroxyl group, wherein all R b1 ~R b4 The total number of carbon atoms is 3 or more, and n3 and n4 are each independently between 0 and 2. In the formula, R b5 L is a hydrogen atom, or a straight-chain or branched alkyl group having 1 to 6 carbon atoms, and L is a single bond, a straight-chain or branched alkylene group having 1 to 3 carbon atoms, an aryl-substituted alkylene group having 7 to 9 carbon atoms, or a group represented by formula (i). Regarding the group shown in formula (i), the benzene ring is bonded to the carbon atom indicated in formula (B2), R b6 R b7 and R b8 Each of the following is independently a linear or branched alkyl group having 1 to 4 carbon atoms, 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, which can be substituted by a fluorine atom; and n6, n7, and n8 are each independently 0 to 3. In the formula, R b9 R is a straight-chain or branched alkyl group with 1 to 4 carbon atoms replaced by fluorine atoms. b10 It is a straight-chain or branched alkyl group with 1 to 4 carbon atoms that can be replaced by fluorine atoms, or an aryl group with 6 to 10 carbon atoms, wherein R b9 With R b10 They can form a ring together, R b11 and R b12 Each of the following is independently a straight-chain or branched alkyl group with 1 to 4 carbon atoms, an alkenyl group with 2 to 4 carbon atoms, an aryl group with 6 to 10 carbon atoms, or a halogen atom, which can be replaced by a fluorine atom or a hydroxyl group; n11 and n12 are each independently 0 to 2. In the formula, R b13 It is a hydrogen atom, a straight-chain or branched alkyl group having 1 to 4 carbon atoms, an alkenyl group having 2 to 4 carbon atoms, an aryl group having 6 to 10 carbon atoms, or an aryl-substituted alkyl group having 7 to 11 carbon atoms, wherein the methylene group (-CH2-) in the alkyl group can be replaced by an oxygen group (-O-). b14 and R b15 Each of the following is independently a straight-chain or branched alkyl group with 1 to 4 carbon atoms, an alkenyl group with 2 to 4 carbon atoms, an aryl group with 6 to 10 carbon atoms, an aryl-substituted alkyl group with 7 to 11 carbon atoms, or a halogen atom, which can be replaced by a fluorine atom; n13, n14, and n15 are each independently 0 to 2. In the formula, R b16 and R b17 Each of the following is independently a hydroxyl group, a straight-chain or branched alkoxy group with 1 to 9 carbon atoms, a straight-chain or branched alkyl group with 1 to 10 carbon atoms that can be replaced by a fluorine atom, an alkenyl group with 2 to 10 carbon atoms, an aryl group with 6 to 10 carbon atoms, or a halogen atom, with n16 being 0 to 3 and n17 being 0 to 2.

2. The reversible thermochromic microcapsule pigment according to claim 1, as component (b), comprises two or more compounds.

3. The reversible thermochromic microcapsule pigment according to claim 1, as component (b), comprises the compound shown in formula (B1).

4. The reversible thermochromic microcapsule pigment according to claim 1, as component (b), comprises the compound shown in formula (B2).

5. The reversible thermochromic microcapsule pigment according to claim 1, as component (b), comprises the compound shown in formula (B1) and the compound shown in formula (B2).

6. The reversible thermochromic microencapsulated pigment according to claim 3 or 5, wherein in the compound represented by formula (B1), R b1 R is a hydrogen atom or a methyl group. b2 It is a straight-chain or branched alkyl or phenyl group with 3 to 11 carbon atoms, where n3 and n4 are both 0, and the hydroxyl groups are each located at the 4 position of the benzene ring.

7. The reversible thermochromic microcapsule pigment according to claim 3 or 5, wherein the compound represented by formula (B1) comprises at least one selected from 1,1-bis(4-hydroxyphenyl)-2-ethylhexane, 1,1-bis(4-hydroxyphenyl)-2-methylpropane, 1,1-bis(4-hydroxyphenyl)-n-decane and 1-phenyl-1,1-bis(4-hydroxyphenyl)ethane.

8. The reversible thermochromic microencapsulated pigment according to claim 4 or 5, wherein in the compound represented by formula (B2), R b5 L is a hydrogen atom or a methyl group, L is a single bond, an ethylene, or a group represented by formula (i) as defined in claim 1, and R is a hydrogen atom or a methyl group. b6 R b7 and R b8 Each of them is independently methyl, ethyl, methoxy, ethoxy, or cyclohexyl, n6, n7, and n8 are each 0 or 1, and the hydroxyl group is located at the 4 position of the benzene ring.

9. The reversible thermochromic microcapsule pigment according to claim 4 or 5, wherein the compound represented by formula (B2) is 4,4'-[1-{4-[1-(4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bisphenol.

10. The reversible thermochromic microcapsule pigment according to claim 1, wherein the mass ratio of component (a) to component (c) is 1:5 to 1:

20.

11. A reversible thermochromic liquid composition comprising the reversible thermochromic microcapsule pigment of any one of claims 1 to 10, and a color carrier.

12. The reversible thermochromic liquid composition according to claim 11, wherein the composition is selected from printing inks, writing instrument inks, coating instrument inks, stamp inks, inkjet inks, coatings, UV-curable inks, painting pigments, cosmetics, and coloring liquids for fibers.

13. A solid writing instrument or solid cosmetic comprising any one of claims 1 to 10, a reversible thermochromic microcapsule pigment, and an excipient.

14. A reversible thermochromic molding resin composition comprising the reversible thermochromic microcapsule pigment according to any one of claims 1 to 10, and the molding resin.

15. A reversible thermochromic molded article, which is formed by molding the reversible thermochromic molding resin composition of claim 14.

16. A reversible thermochromic laminate comprising a support and a reversible thermochromic layer comprising the reversible thermochromic microcapsule pigment according to any one of claims 1 to 10.

17. A writing instrument comprising the reversible thermochromic liquid composition of claim 11.

18. The writing instrument according to claim 17, comprising a friction member that causes the ink obtained by using the writing instrument to change color through frictional heat.

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