Reversible thermochromic composition and reversible thermochromic microcapsule pigment containing same

Abstract

Provided are: a reversible thermochromic composition which takes on highly fluorescent red or pink color at the time of color development; and a reversible thermochromic microcapsule pigment containing the same.　Provided is a reversible thermochromic composition which comprises at least: (a) a fluoran derivative which serves as an electron-donating coloring organic compound and has a specific structure; (b) an electron-accepting compound; and (c) a reaction medium that reversibly causes an electron transfer reaction by means of component (a) and component (b) in a specific temperature range. Also provided is a reversible thermochromic microcapsule pigment which contains the reversible thermochromic composition.

Description

Reversible thermochromic composition and reversible thermochromic microcapsule pigment containing the same.

[0001] This patent application is made with a claim of priority based on Japanese Patent Application No. 2024-229777, filed on 26 December 2024, and the entire disclosures in the said prior patent application are incorporated herein by reference.

[0002] This disclosure relates to a reversible thermochromic composition and a reversible thermochromic microcapsule pigment containing the same. More specifically, it relates to a reversible thermochromic composition that exhibits a highly fluorescent red to pink color upon color development and a reversible thermochromic microcapsule pigment containing the same.

[0003] Conventionally, a reversible thermochromic composition has been disclosed that reversibly changes color from red or pink to colorless, comprising a specific diazarhodamine lactone derivative as an electron-donating chromogenic organic compound, an electron-accepting compound, and a reaction medium that reversibly causes an electron transfer reaction between the electron-donating chromogenic organic compound and the electron-accepting compound in a certain temperature range (see, for example, Patent Document 1).

[0004] Japanese Patent Application Publication No. 11-105428

[0005] This disclosure aims to provide a reversible thermochromic composition of this type that exhibits a highly fluorescent red to pink color when it develops color, and a reversible thermochromic microcapsule pigment containing the same.

[0006] This disclosure requires a reversible thermochromic composition comprising at least (a) a fluorane derivative represented by the following general formula (1) as an electron-donating chromogenic organic compound, (b) an electron-accepting compound, and (c) a reaction medium that reversibly causes the electron transfer reaction between components (a) and (b) to occur in a specific temperature range. [In general formula (1), R １１ and R １３ R independently represents an alkyl group which may have substituents, １２ and R １４ R represents a group that is independently represented by the following general formula (2), １５represents a halogen atom, an alkyl group which may have a substituent or an alkoxy group which may have a substituent, and a represents an integer from 0 to 4. When a represents an integer from 2 to 4, a plurality of R １５ may be the same or different. In general formula (2), R ２１ and R ２２ each independently represent an alkyl group which may have a substituent, and b represents an integer from 1 to 4. When b represents an integer from 2 to 4, a plurality of R ２２ may be the same or different. * indicates the bonding site with the nitrogen atom in general formula (1). Further, in general formula (1), R １１ and R １３ each independently is an alkyl group having 6 to 12 carbon atoms which may have a substituent, or a group represented by the following general formula (3), [In general formula (3), R ３１ represents a halogen atom, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, -C(O)-R ３２ , -C(O)-O-R ３３ , -O-C(O)-R ３４ , -SO ２ -R ３５ , a nitro group or a cyano group, R ３２ , R ３３ and R ３４ each independently represent a hydrogen atom, an alkyl group which may have a substituent or an aryl group which may have a substituent, R ３５ represents a hydroxy group, an alkyl group which may have a substituent or an aryl group which may have a substituent, L represents an alkylene group which may have a substituent, and c represents an integer from 0 to 5. When c represents an integer from 2 to 5, a plurality of R ３１ may be the same or different. * indicates the bonding site with the nitrogen atom in general formula (1). Further, in general formula (1), R １１ and R １３ each independently is an alkyl group having 6 to 12 carbon atoms, or a group represented by the general formula (3), and in general formula (3), R ３１This includes halogen atoms, C1-C6 alkyl groups, C1-C6 alkoxy groups, and -C(O)-R ３２ , -C(O)-OR ３３ , -O-C(O)-R ３４ , -SO ２ -R ３５ , represents a nitro group or a cyano group, R ３２ , R ３３ and R ３４ Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms which may have substituents, or an aryl group having 6 to 12 carbon atoms which may have substituents, R ３５ R represents a hydroxyl group, an optionally substituted C1-C6 alkyl group, or an optionally substituted C6-C12 aryl group; L represents a C1-C4 alkylene group; c represents an integer from 0 to 2; if c is 2, then two R ３１ They may be the same or they may be different, and furthermore, in general formula (2), R ２１ and R ２２ Each of the following independently represents an alkyl group having 1 to 6 carbon atoms, and b represents an integer from 1 to 3. If b represents an integer from 2 to 3, then multiple R ２２ They may be the same or they may be different, and furthermore, in general formula (1), R １１ and R １３ These are groups that are independently represented by the general formula (3), and R １５ R is a halogen atom, a C1-C4 alkyl group, or a C1-C4 alkoxy group, where a is an integer from 0 to 1, and in general formula (2), R ２１ and R ２２ R represents an alkyl group with 1 to 4 carbon atoms, and b represents an integer from 1 to 2. When b represents 2, two R ２２ They may be the same or different, and in general formula (3), R ３１ represents a halogen atom, a cyano group, or an alkyl group having 1 to 4 carbon atoms; L represents an alkylene group having 1 to 2 carbon atoms; c represents an integer from 1 to 2; if c represents 2, then two R ３１The requirements include that these components may be the same or different. Furthermore, the requirements include that the components are contained in an amount of 0.1 to 100 parts by mass of component (b) and 1 to 800 parts by mass of component (c) per 1 part by mass of component (a), a reversible thermochromic microcapsule pigment containing the reversible thermochromic composition, a reversible thermochromic liquid composition comprising the reversible thermochromic microcapsule pigment and a vehicle, a reversible thermochromic moldable resin composition comprising the reversible thermochromic microcapsule pigment and a molding resin, a reversible thermochromic laminate comprising a support and a reversible thermochromic layer containing the reversible thermochromic microcapsule pigment.

[0007] This disclosure provides a reversible thermochromic composition that exhibits a highly fluorescent red to pink color when colored, and a reversible thermochromic microcapsule pigment containing the same, by using a specific fluorane derivative as an electron-donating colored organic compound.

[0008] This graph illustrates the hysteresis characteristics in the color density-temperature curve of a heat-decolorizing, reversible thermochromic composition. This graph illustrates the hysteresis characteristics in the color density-temperature curve of a heat-decolorizing, reversible thermochromic composition with color memory properties. This graph illustrates the hysteresis characteristics in the color density-temperature curve of a heat-developing, reversible thermochromic composition.

[0009] Examples of the reversible thermochromic composition include a reversible thermochromic composition of the heat-decolorizing type (which decolorizes upon heating and develops color upon cooling) comprising three components: (a) an electron-donating color-developing organic compound, (b) an electron-accepting compound, and (c) a reaction medium that determines the temperature at which the color reaction of components (a) and (b) occurs. As the aforementioned reversible thermochromic composition, a reversible thermochromic composition of the heat-decolorizing type (decolorizes when heated and develops color when cooled) can be applied, as described in Japanese Patent Publication No. 51-44706, Japanese Patent Publication No. 51-44707, Japanese Patent Publication No. 1-29398, etc., which changes color before and after a predetermined temperature (color change point), exhibits a decolorized state in the temperature range above the high-temperature color change point and a colored state in the temperature range below the low-temperature color change point, and of the two states, only one specific state exists in the room temperature range (normal living temperature range), and the other state is maintained as long as the heat or cold required to bring about that state is applied, but returns to the state exhibited in the room temperature range when the application of heat or cold is stopped, and which has a relatively small hysteresis width (ΔH = 1 to 7°C) (see Figure 1). Also, Japanese Patent Publication No. 4-17154, Japanese Patent Publication No. 7-179777, Japanese Patent Publication No. 7-33997, Japanese Patent Publication No. 8-39936, Japanese Patent Publication No. 2006-137880, Japanese Patent Publication No. 2008-280523, International Publication No. 2010 / 131684, International Publication No. 2010 / 131684, International Publication No. 2012 / 046837, International Publication No. 2014 / 200053, International Publication No. 2015 / 119161, International Publication No. 2016 / 027 The hysteresis width (ΔH) described in publications such as No. 664, International Publication No. 2017 / 022471, and International Publication No. 2018 / 155583 is relatively large, ranging from 8 to 80°C. In other words, the shape of the curve plotting the change in color intensity due to temperature changes follows a significantly different path when the temperature is raised from a temperature below a specific temperature range (color change temperature range) compared to when it is lowered from a temperature above a specific temperature range (color change temperature range), and the complete color development temperature (t １ The color development state in the low temperature range below ) or the complete decolorization temperature (t ４ The decolorization state at temperatures above ) is determined by the color development start temperature t. ２ ~Discoloration start temperature t ３A reversible thermochromic composition that exhibits color memory in the temperature range between (effectively the two-phase retention temperature range) and is heat-decolorizable (decolorizes upon heating and develops color upon cooling) can also be applied (see Figure 2).

[0010] The hysteresis characteristics in the color density-temperature curve of the aforementioned reversible thermochromic composition will now be explained. In Figure 2, the vertical axis represents color density and the horizontal axis represents temperature. The change in color density due to temperature changes progresses along the arrow. Here, A is the temperature t at which complete decolorization is reached. ４ This point represents the concentration at the (hereinafter referred to as the complete decolorization temperature), where B is the temperature t at which decolorization begins. ３ This point indicates the concentration at the (hereinafter referred to as the decolorization start temperature), where C is the temperature t at which color development begins. ２ This point indicates the density at the (hereinafter referred to as the color development start temperature), where D is the temperature t at which the color development state is reached. １ This point indicates the concentration at the temperature at which the color develops completely (hereinafter referred to as the full color temperature). The specific temperature range is the aforementioned t １ and t ４ This is a temperature range where the color can be either colored or decolorized, and it is a region where the difference in color density is large. ２ and t ３ The temperature range between these two points is the effective discoloration temperature range. Furthermore, the length of line segment EF is a measure of the discoloration contrast, and the length of line segment HG passing through the midpoint of line segment EF is the temperature range indicating the degree of hysteresis (hereinafter referred to as the hysteresis range ΔH). A small ΔH value means that only one of the two states before and after discoloration can exist in the room temperature range. Conversely, a large ΔH value makes it easier to maintain each state before and after discoloration. Here, the complete decolorization temperature t is defined as... ４ The temperature is in the range of 40 to 95°C, preferably 45 to 95°C, and more preferably 50 to 95°C, so that the color can be removed by simple methods such as rubbing with a finger or rubbing with a friction object. １ By maintaining a temperature in the range of -50 to 5°C, preferably -50 to 0°C, and more preferably -50 to -5°C—a temperature not reached in normal living conditions—the discolored state can be maintained within the normal temperature range. Note that normal temperature is defined as 20±15°C as specified in JIS Z 8703, and the normal temperature range is defined as a temperature range of 5°C to 35°C.

[0011] The components (a), (b), and (c) included in the reversible thermochromic composition will be described in detail below. Component (a), i.e., the electron-donating chromogenic organic compound, is the component that determines the color and is a compound that produces color by donating electrons to component (b), which is the color developer. As the electron-donating chromogenic organic compound, a fluorane derivative represented by general formula (1) is used. [In general formula (1), R １１ and R １３ R independently represents an alkyl group which may have substituents, １２ and R １４ R represents a group that is independently represented by the following general formula (2), １５ R represents a halogen atom, an optionally substituted alkyl group, or an optionally substituted alkoxy group, and a represents an integer from 0 to 4. When a represents an integer from 2 to 4, multiple R １５ They may be the same or they may be different. In general formula (2), R ２１ and R ２２ R independently represents an alkyl group which may have substituents, and b represents an integer from 1 to 4. When b represents an integer from 2 to 4, multiple R ２２ These may be the same or different. * indicates the bonding site with the nitrogen atom in general formula (1).

[0012] R in general formula (1) １１ , R １３ and R １５ , R in general formula (2) ２１ and R ２２Examples of alkyl groups that may have substituents include alkyl groups having 1 to 20 carbon atoms that may have substituents. Examples of alkyl groups that may have substituents include linear, branched, or cyclic alkyl groups having 1 to 20 carbon atoms that may have substituents. Examples of linear, branched, or cyclic alkyl groups include linear alkyl groups such as methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, isopropyl group, isobutyl group, sec-butyl group, tert-butyl group, 2-methylbutyl group, 1-methylbutyl group, neopentyl group Group, 1,2-dimethylpropyl group, 1,1-dimethylpropyl group, 4-methylpentyl group, 3-methylpentyl group, 2-methylpentyl group, 1-methylpentyl group, 3,3-dimethylbutyl group, 2,3-dimethylbutyl group, 1,3-dimethylbutyl group, 2,2-dimethylbutyl group, 1,2-dimethylbutyl group, 1,1-dimethylbutyl group, 3-ethylbutyl group, 2-ethylbutyl group, 1-ethylbutyl group, 1,1,2-trimethylpropyl group, 1-ethyl-2-methyl Propyl group, 2-methylhexyl group, 3-methylhexyl group, 4-methylhexyl group, 5-methylhexyl group, 1-ethylpentyl group, 2,4-dimethylpentyl group, 2-ethylhexyl group, 2,5-dimethylhexyl group, 2,5,5-trimethylpentyl group, 2,4-dimethylhexyl group, 2,2,4-trimethylpentyl group, 1,1-dimethylhexyl group, 1,1,3,3-tetramethylbutyl group, 3,5,5-trimethylhexyl group, 4-ethyloctyl group, 4 Examples include branched alkyl groups such as -ethyl-4,5-dimethylhexyl group, 1,3,5,7-tetramethyloctyl group, 4-butyloctyl group, 6,6-diethyloctyl group, 6-methyl-4-butyloctyl group, 3,5-dimethylheptadecyl group, 2,6-dimethylheptadecyl group, 2,4-dimethylheptadecyl group, and 2,2,5,5-tetramethylhexyl group, as well as cyclic alkyl groups such as cyclopropyl group, cyclobutyl group, cyclopentyl group, and cyclohexyl group.

[0013] The substituents in the alkyl group, which may have substituents, are not particularly limited and include, for example, aryl groups having 6 to 10 carbon atoms that may have substituents (phenyl group, naphthyl group, 2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 2-fluorophenyl group, 3-fluorophenyl group, 4-fluorophenyl group, 2-chlorophenyl group, 3-chlorophenyl group, 4-chlorophenyl group, 2,4-dichlorophenyl group, 2-bromophenyl group, 2-cyanophenyl group, etc.), linear, branched, or cyclic alkoxy groups having 1 to 8 carbon atoms, amino groups, mono- or di- Examples include alkylamino groups (alkyl groups have 1 to 8 carbon atoms), halogen atoms, cyano groups, hydroxyl groups, nitro groups, carboxyl groups, alkoxycarbonyl groups with 1 to 8 carbon atoms, acyl groups with 2 to 12 carbon atoms (e.g., acetyl group, propionyl group, butyryl group, valeryl group, pivaloyl group, acryloyl group, methacryloyl group, benzoyl group, toluyl group, cinnamoyl group, anisoyl group, naphthoyl group, etc.), acyloxy groups with 2 to 12 carbon atoms, and alkenyl groups with 2 to 10 carbon atoms (e.g., vinyl group, 1-propenyl group, allyl group, butenyl group, styryl group, etc.). Examples of substituents on a cyclic alkyl group, which may have substituents, include linear or branched alkyl groups having 1 to 10 carbon atoms (e.g., methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, 2-methylbutyl group, 1-methylbutyl group, neopentyl group, 1,2-dimethylpropyl group, 1,1-dimethylpropyl group, etc.). When an alkyl group has substituents, if there are two or more substituents, each substituent may be the same or different. In one embodiment, the substituents on the alkyl group are preferably halogen atoms or aryl groups having 6 to 10 carbon atoms, which may have substituents.

[0014] Examples of the halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms. Preferably, fluorine atoms, chlorine atoms, and bromine atoms are used.

[0015] R in general formula (1) １１ and R １３Examples of the alkyl group having a substituent in [compound name] include a group represented by the following general formula (3). In the compound of the present disclosure, R in general formula (1) １１ and R １３ are each independently preferably an alkyl group having 6 to 12 carbon atoms which may have a substituent, or a group represented by the following general formula (3). In general formula (3), R ３１ represents a halogen atom, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, -C(O)-R ３２ , -C(O)-O-R ３３ , -O-C(O)-R ３４ , -SO2-R ３５ , a nitro group or a cyano group, R ３２ , R ３３ and R ３４ each independently represent a hydrogen atom, an alkyl group which may have a substituent or an aryl group which may have a substituent, R ３５ represents a hydroxy group, an alkyl group which may have a substituent or an aryl group which may have a substituent, L represents an alkylene group which may have a substituent, and c represents an integer from 0 to 5. When c represents an integer from 2 to 5, the plurality of R ３１ may be the same or different. * indicates the bonding site with the nitrogen atom in general formula (1).

[0016] R １１ and R １３ are each independently preferably an alkyl group having 6 to 12 carbon atoms which may have a substituent, or a group represented by the following general formula (3). Examples of the alkyl group having 6 to 12 carbon atoms which may have a substituent include an alkyl group having 6 to 12 carbon atoms which may be substituted with a halogen atom, more preferably an alkyl group having 6 to 12 carbon atoms, still more preferably a linear or branched alkyl group having 6 to 12 carbon atoms, still more preferably a linear or branched alkyl group having 6 to 10 carbon atoms, particularly preferably a linear alkyl group having 6 to 10 carbon atoms, and most preferably a linear alkyl group having 6 to 8 carbon atoms.

[0017] In one aspect, R １１ and R１３ is more preferably a group represented by the general formula (3) independently of each other. R in the general formula (3) ３１ , R ３２ , R ３３ , R ３４ and R ３５ As the alkyl group which may have a substituent in, the R in the above-mentioned general formula (1) １１ , R １３ and R １５ , the R in the general formula (2) ２１ and R ２２ are the same as the alkyl groups which may have a substituent in. R ３１ , R ３２ , R ３３ , R ３４ and R ３５ As the alkyl group which may have a substituent in, an alkyl group having 1 to 6 carbon atoms which may have a substituent is preferable, an alkyl group having 1 to 6 carbon atoms (preferably a linear or branched alkyl group) is more preferable, an alkyl group having 1 to 4 carbon atoms is further preferable, a methyl group, an ethyl group, a tert-butyl group are even more preferable, a methyl group and an ethyl group are particularly preferable, and a methyl group is most preferable.

[0018] In R ３１ in the general formula (3), examples of the alkoxy group which may have a substituent include an alkoxy group having 1 to 20 carbon atoms which may have a substituent. Further, examples of the alkoxy group include a linear, branched or cyclic alkoxy group, and preferably a linear or branched alkoxy group. As the linear, branched or cyclic alkoxy group, for example, a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an n-pentyloxy group, an isopentyloxy group, a neopentyloxy group, an n-hexyloxy group, a 2-ethylhexyloxy group, a cyclohexyloxy group, an n-dodecyloxy group can be mentioned.

[0019] The substituents in the alkoxy group, which may have substituents, are not particularly limited and include, for example, halogen atoms, hydroxyl groups, linear, branched, or cyclic alkoxy groups having 1 to 18 carbon atoms, monocyclic or polycyclic aryl groups having 6 to 16 carbon atoms, alkoxycarbonyl groups having 1 to 8 carbon atoms, amino groups, mono- or di-alkylamino groups (alkyl groups having 1 to 8 carbon atoms), and the like.

[0020] R ３２ , R ３３ , R ３４ and R ３５ Examples of optionally substituted aryl groups include aryl groups having 6 to 20 carbon atoms that may have substituents. The aryl group is not particularly limited and includes, for example, monocyclic aromatic hydrocarbon groups such as phenyl groups, and polycyclic aromatic hydrocarbon groups such as naphthyl groups, anthracenyl groups, naphthacenyl groups, pentacenyl groups, phenantrenyl groups, and pyrenyl groups. Among these, phenyl groups and naphthyl groups are preferred as aryl groups, with phenyl groups being more preferred.

[0021] The substituents in the aryl group, which may have substituents, are not particularly limited and include, for example, linear, branched, or cyclic alkyl groups having 1 to 8 carbon atoms, alkoxy groups having 1 to 8 carbon atoms, amino groups, mono- or di-alkylamino groups (alkyl groups having 1 to 8 carbon atoms), halogen atoms, cyano groups, hydroxyl groups, nitro groups, halogenated hydrocarbon groups having 1 to 8 carbon atoms, carboxyl groups, alkoxycarbonyl groups having 1 to 8 carbon atoms, and monocyclic or polycyclic aryl groups having 6 to 14 carbon atoms. Preferably, the substituents are linear, branched, or cyclic alkyl groups having 1 to 8 carbon atoms and halogen atoms. When the aryl group has substituents, if there are two or more substituents, each substituent may be the same or different. Examples of substituted aryl groups include nitrophenyl, cyanophenyl, hydroxyphenyl, carboxyphenyl, methylphenyl, dimethylphenyl, trimethylphenyl, fluorophenyl, chlorophenyl, bromophenyl, methoxyphenyl, ethoxyphenyl, trifluoromethylphenyl, N,N-dimethylaminophenyl, nitronaphthyl, cyanonaphthyl, hydroxynaphthyl, methylnaphthyl, fluoronaphthyl, chloronaphthyl, bromonaphthyl, trifluoromethylnaphthyl, phenoxyphenyl, and biphenyl groups.

[0022] In general formula (3), R ３１ This includes halogen atoms, C1-C6 alkyl groups, C1-C6 alkoxy groups, and -C(O)-R ３２ , -C(O)-OR ３３ , -O-C(O)-R ３４ , -SO2-R ３５ It is preferable to represent a nitro group or a cyano group. ３１ In this, the alkyl group is preferably a linear or branched alkyl group. ３１ R is more preferably a halogen atom, a cyano group, or an alkyl group having 1 to 6 carbon atoms, even more preferably a halogen atom, a cyano group, or an alkyl group having 1 to 4 carbon atoms, particularly preferably a halogen atom, a cyano group, a methyl group, an ethyl group, or a tert-butyl group, and most preferably a halogen atom, a cyano group, or a methyl group.３１ The halogen atoms in this mixture are preferably fluorine atoms, chlorine atoms, and bromine atoms.

[0023] R ３２ , R ３３ and R ３４ It is preferable that each of the following independently represents a hydrogen atom, an optionally substituted C1-C6 alkyl group, or an optionally substituted C6-C12 aryl group, and more preferably independently represents a hydrogen atom or a C1-C4 alkyl group. The alkyl group is preferably a linear or branched alkyl group. ３５ It is preferable that this represents a hydroxyl group, an alkyl group having 1 to 6 carbon atoms which may have substituents, or an aryl group having 6 to 12 carbon atoms which may have substituents, and more preferably a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, or an aryl group having 6 to 12 carbon atoms.

[0024] In general formula (3), L preferably represents an alkylene group having 1 to 4 carbon atoms, the number of carbon atoms in the alkylene group is preferably 1 to 3, more preferably 1 to 2, and particularly preferably 1. L is particularly preferably a methylene group. In general formula (3), c preferably represents an integer from 0 to 3, and more preferably an integer from 0 to 2. c is more preferably an integer of 0, 1, or 2.

[0025] In one embodiment, in general formula (3), R ３１ It is preferable that represents a halogen atom, a cyano group, or an alkyl group having 1 to 4 carbon atoms, L represents an alkylene group having 1 to 2 carbon atoms, and c represents an integer from 1 to 2. When c represents 2, two R ３１ They may be the same or they may be different. More preferably, R ３１ It is preferable that represents a fluorine atom, a chlorine atom, a bromine atom, a methyl group, an ethyl group, or a cyano group. It is preferable that L represents a C1 alkylene group (methylene group).

[0026] Preferred groups represented by general formula (3) are phenyl group, 2-methylphenyl group, 2-fluorophenyl group, 3-fluorophenyl group, 2-chlorophenyl group, 3-chlorophenyl group, 4-chlorophenyl group, 2,4-dichlorophenyl group, 2-bromophenyl group, and 2-cyanophenyl group.

[0027] In general formula (2), R ２１ and R ２２ It is preferable that each of them independently represents an alkyl group having 1 to 6 carbon atoms, and more preferably that they represent an alkyl group having 1 to 4 carbon atoms. ２１ and R ２２ As the alkyl group in, a linear or branched alkyl group is preferred. In one embodiment, R ２１ and R ２２ b is more preferably a linear or branched alkyl group having 1 to 6 carbon atoms, more preferably a linear or branched alkyl group having 1 to 4 carbon atoms, even more preferably a linear or branched alkyl group having 1 to 3 carbon atoms, particularly preferably a methyl group or an ethyl group, and most preferably a methyl group. b is preferably an integer from 1 to 3, more preferably an integer from 1 to 2, and even more preferably 1.

[0028] In one embodiment, R in general formula (2) ２１ and R ２２ Each of the R22 groups independently represents an alkyl group having 1 to 4 carbon atoms, and b preferably represents an integer from 1 to 2, more preferably b represents 1. When b represents 2, the two R22 groups may be the same or different.

[0029] In general formula (1), R １５ R is preferably a halogen atom, a C1-C4 alkyl group, or a C1-C4 alkoxy group, more preferably a halogen atom or a C1-C4 linear or branched alkyl group, and even more preferably a halogen atom, a methyl group, or an ethyl group. １５In the halogen atom, a fluorine atom or a chlorine atom is preferred. In general formula (1), a is preferably an integer from 0 to 2, more preferably 0 or 1, and even more preferably 0.

[0030] In one embodiment, in general formula (1), R １１ and R １３ Each of the above general formulas (3) represents a linear alkyl group having 8 carbon atoms, independently of the others, where a is 0, and in general formula (2), R ２１ and R ２２ represents a methyl group, b is 1, and in general formula (3), R ３１ A compound is preferred in which represents a halogen atom, a cyano group, or a methyl group, L represents a methylene group, and c is an integer from 0 to 2. More preferably R １１ and R １３ These represent groups that are independently expressed by general formula (3).

[0031] Examples of fluorane derivatives represented by general formula (1) are given below.

[0032]

[0033]

[0034]

[0035] The aforementioned component (b), i.e., the electron-accepting compound, is a compound that accepts electrons from component (a) and functions as a color developer for component (a). The electron-accepting compound can be selected from a group of compounds having active protons and their derivatives, a group of pseudoacidic compounds (compounds that are not acids but act as acids in the composition to cause component (a) to develop color), a group of compounds having electron vacancies, etc., and among these, compounds selected from the group of compounds having active protons are preferred. Examples of compounds having active protons and their derivatives include compounds having phenolic hydroxyl groups and their metal salts, carboxylic acids and their metal salts, preferably aromatic carboxylic acids, aliphatic carboxylic acids having 2 to 5 carbon atoms and their metal salts, acidic phosphate esters and their metal salts, as well as azole compounds and their derivatives, 1,2,3-triazole and its derivatives, and among these, compounds having phenolic hydroxyl groups are preferred because they can exhibit effective thermal color change properties. The aforementioned compounds having phenolic hydroxyl groups broadly include monophenol compounds to polyphenol compounds, and further include bis-type, tris-type phenols, and phenol-aldehyde condensation resins. Among compounds having phenolic hydroxyl groups, those having at least two benzene rings are preferred. These compounds may also have substituents, such as alkyl groups, aryl groups, acyl groups, alkoxycarbonyl groups, carboxyl groups and their esters or amide groups, and halogen groups. Examples of metals included in the metal salts of the compounds having active protons include sodium, potassium, calcium, zinc, zirconium, aluminum, magnesium, nickel, cobalt, tin, copper, iron, vanadium, titanium, lead, and molybdenum.

[0036] The following are specific examples: Phenol, o-cresol, tert-butylcatechol, nonylphenol, n-octylphenol, n-dodecylphenol, n-stearylphenol, p-chlorophenol, p-bromophenol, o-phenylphenol, n-butyl p-hydroxybenzoate, n-octyl p-hydroxybenzoate, resorcinol, dodecyl gallate, 4,4-dihydroxydiphenylsulfone, bis(4-hydroxyphenyl)sulfide, 1,1-bis(4-hydroxyphenyl)ethane, 1,1-bis(4-hydroxyphenyl ) Propane, 1,1-bis(4-hydroxyphenyl)n-butane, 1,1-bis(4-hydroxyphenyl)n-pentane, 1,1-bis(4-hydroxyphenyl)n-hexane, 1,1-bis(4-hydroxyphenyl)n-heptane, 1,1-bis(4-hydroxyphenyl)n-octane, 1,1-bis(4-hydroxyphenyl)n-nonane, 1,1-bis(4-hydroxyphenyl)n-decane, 1,1-bis(4-hydroxyphenyl)n-dodecane, 1,1-bis(4-hydroxyphenyl)-2-methylpropane, 1 1-bis(4-hydroxyphenyl)-3-methylbutane, 1,1-bis(4-hydroxyphenyl)-3-methylpentane, 1,1-bis(4-hydroxyphenyl)-2,3-dimethylpentane, 1,1-bis(4-hydroxyphenyl)-2-ethylbutane, 1,1-bis(4-hydroxyphenyl)-2-ethylhexane, 1,1-bis(4-hydroxyphenyl)-3,7-dimethyloctane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylhexane Crohexane, 1-phenyl-1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxyphenyl)n-butane, 2,2-bis(4-hydroxyphenyl)n-pentane, 2,2-bis(4-hydroxyphenyl)n-hexane, 2,2-bis(4-hydroxyphenyl)n-heptane, 2,2-bis(4-hydroxyphenyl)n-octane, 2,2-bis(4-hydroxyphenyl)n-nonane, 2,2-bis(4-hydroxyphenyl)n-decane, 2,Examples include 2-bis(4-hydroxyphenyl)n-dodecane, 2,2-bis(4-hydroxyphenyl)ethylpropionate, 2,2-bis(4-hydroxyphenyl)-4-methylpentane, 2,2-bis(4-hydroxyphenyl)-4-methylhexane, 2,2-bis(4-hydroxyphenyl)hexafluoropropane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, 1,1-bis[2-(4-hydroxyphenyl)-2-propyl]benzene, bis(2-hydroxyphenyl)methane, 1,1,1-tris(4-hydroxyphenyl)ethane, and 3,3-bis(3-methyl-4-hydroxyphenyl)butane. The compound having the phenolic hydroxyl group exhibits the most effective thermal color change properties, but compounds selected from aromatic carboxylic acids and aliphatic carboxylic acids having 2 to 5 carbon atoms, carboxylic acid metal salts, acidic phosphate esters and their metal salts, 1,2,3-triazoles and their derivatives may also be used.

[0037] The component (c) of the reaction medium that reversibly causes the electron transfer reaction by the components (a) and (b) described above to occur in a specific temperature range will now be explained. Examples of the component (c) include alcohols, esters, ketones, ethers, and acid amides. When the component (c) is used in microencapsulation and secondary processing described later, low molecular weight compounds tend to evaporate outside the capsule when subjected to high heat treatment, so compounds with 10 or more carbon atoms are preferably used to stably retain them inside the capsule. As for alcohols, aliphatic monovalent saturated alcohols with 10 or more carbon atoms are effective, and specific examples include decyl alcohol, undecyl alcohol, dodecyl alcohol, tridecyl alcohol, tetradecyl alcohol, pentadecyl alcohol, hexadecyl alcohol, heptadecyl alcohol, octadecyl alcohol, eicosyl alcohol, docosyl alcohol, etc.

[0038] As for esters, esters with 10 or more carbon atoms are effective, and esters obtained from any combination of a monohydric carboxylic acid having an aliphatic and alicyclic or aromatic ring and a monohydric alcohol having an aliphatic and alicyclic or aromatic ring, esters obtained from any combination of a polyhydric carboxylic acid having an aliphatic and alicyclic or aromatic ring and a monohydric alcohol having an aliphatic and alicyclic or aromatic ring, or any combination of a monohydric carboxylic acid having an aliphatic and alicyclic or aromatic ring and a polyhydric alcohol having an aliphatic and alicyclic or aromatic ring Examples of esters obtained from these include, specifically, ethyl caprylate, octyl caprylate, stearyl caprylate, myristyl caprate, docosyl caprate, 2-ethylhexyl laurate, n-decyl laurate, 3-methylbutyl myristate, myristyl myristate, cetyl myristate, isopropyl palmitate, neopentyl palmitate, nonyl palmitate, cyclohexyl palmitate, n-butyl stearate, 2-methylbutyl stearate, and 3,5,5-trimethylhexyl stearate. n-undecyl stearate, pentadecyl stearate, stearyl stearate, cyclohexylmethyl stearate, isopropyl behenate, hexyl behenate, lauryl behenate, behenyl behenate, cetyl benzoate, p-tert-butyl stearyl benzoate, dimyristyl phthalate, distearyl phthalate, dimyristyl oxalate, dicetyl oxalate, dicetyl malonate, dilauryl succinate, dilauryl glutarate, diundecyl adipate, dilauryl azelaate, di-(n-nonyl) sebacate Examples include 1,18-octadecylmethylenedicarboxylic acid dineopentyl, ethylene glycol dimyristate, propylene glycol dilaurate, propylene glycol distearate, hexylene glycol dipalmitate, 1,5-pentanediol distearate, 1,2,6-hexanetriol trimyristate, 1,4-cyclohexanediol didecyl, 1,4-cyclohexanedimethanol dimyristate, xylene glycol dicaprinate, xylene glycol distearate, etc.

[0039] Furthermore, ester compounds selected from saturated fatty acids and branched aliphatic alcohols, unsaturated fatty acids or branched or substituted saturated fatty acids and branched or aliphatic alcohols having 16 or more carbon atoms, cetyl butyrate, stearyl butyrate, and behenyl butyrate are also effective.Specifically, 2-ethylhexyl butyrate, 2-ethylhexyl behenate, 2-ethylhexyl myristate, 2-ethylhexyl caprate, 3,5,5-trimethylhexyl laurate, 3,5,5-trimethylhexyl palmitate, 3,5,5-trimethylhexyl stearate, 2-methylbutyl caproate, 2-methylbutyl caprylate, 2-methylbutyl caprate, 1-ethylpropyl palmitate, 1-ethylpropyl stearate, 1-ethylpropyl behenate, 1-ethylhexyl laurate Xyl, 1-ethylhexyl myristate, 1-ethylhexyl palmitate, 2-methylpentyl caproate, 2-methylpentyl caprylate, 2-methylpentyl caprate, 2-methylpentyl laurate, 2-methylbutyl stearate, 2-methylbutyl stearate, 3-methylbutyl stearate, 1-methylheptyl stearate, 2-methylbutyl behenate, 3-methylbutyl behenate, 1-methylheptyl stearate, 1-methylheptyl behenate, 1-ethylpentyl caproate, 1-ethylpentyl palmitate, 1-methylpropyl stearate, 1-methyloctyl stearate, 1-methylhexyl stearate, 1,1-dimethylpropyl laurate, 1-methylpentyl caprate, 2-methylhexyl palmitate, 2-methylhexyl stearate, 2-methylhexyl behenate, 3,7-dimethyloctyl laurate, 3,7-dimethyloctyl myristate, 3,7-dimethyloctyl palmitate, 3,7-dimethyloctyl stearate, 3,7-dimethyloctyl behenate Examples include thiooctyl oleate, stearyl oleate, behenyl oleate, stearyl linoleate, behenyl linoleate, 3,7-dimethyloctyl erucate, stearyl erucate, isostearyl erucate, cetyl isostearate, stearyl isostearate, 2-methylpentyl 12-hydroxystearate, 2-ethylhexyl 18-bromostearate, isostearyl 2-ketomyristate, 2-ethylhexyl 2-fluoromyristate, cetyl butyrate, stearyl butyrate, and behenyl butyrate.

[0040] Furthermore, in order to exhibit a large hysteresis characteristic with respect to the color density-temperature curve and change color, thereby providing color memory depending on temperature changes, examples of carboxylic acid ester compounds that exhibit a ΔT value (melting point-cloud point) of 5°C or more and less than 50°C as described in Japanese Patent Publication No. 4-17154 include carboxylic acid esters containing a substituted aromatic ring in the molecule, esters of carboxylic acids containing an unsubstituted aromatic ring and aliphatic alcohols having 10 or more carbon atoms, carboxylic acid esters containing a cyclohexyl group in the molecule, esters of fatty acids having 6 or more carbon atoms and unsubstituted aromatic alcohols or phenols, esters of fatty acids having 8 or more carbon atoms and branched aliphatic alcohols, esters of dicarboxylic acids and aromatic alcohols or branched aliphatic alcohols, dibenzyl cinnamate, heptyl stearate, didecyl adipate, dilauryl adipate, dimyristyl adipate, dicetyl adipate, distearyl adipate, trilaurin, trimiristine, tristearin, dimyristine, distearin, etc.

[0041] Fatty acid ester compounds obtained from an odd-numbered aliphatic monohydric alcohol having 9 or more carbon atoms and an even-numbered aliphatic carboxylic acid, and fatty acid ester compounds with a total of 17 to 23 carbon atoms obtained from n-pentyl alcohol or n-heptyl alcohol and an even-numbered aliphatic carboxylic acid having 10 to 16 carbon atoms are also effective. Specifically, n-pentadecyl acetate, n-tridecyl butyrate, n-pentadecyl butyrate, n-undecyl caproate, n-tridecyl caproate, n-pentadecyl caproate, n-nonyl caprylate, n-undecyl caprylate, n-tridecyl caprylate, n-pentadecyl caprylate, n-heptyl caprate, n-nonyl caprate, n-undecyl caprate, n-tridecyl caprate, n-pentadecyl caprate, n-pentyl laurate, n-heptyl laurate, n-nonyl laurate, n-undecyl laurate, n-tridecyl laurate, n-pentadecyl laurate, n-pentyl myristate, n-heptyl myristate, myristic acid Examples include n-nonyl acid, n-undecyl myristate, n-tridecyl myristate, n-pentadecyl myristate, n-pentyl palmitate, n-heptyl palmitate, n-nonyl palmitate, n-undecyl palmitate, n-tridecyl palmitate, n-pentadecyl palmitate, n-nonyl stearate, n-undecyl stearate, n-tridecyl stearate, n-pentadecyl stearate, n-nonyl eicosanoate, n-undersi eicosanoate, n-tridecyl eicosanoate, n-pentadecyl eicosanoate, n-nonyl behenate, n-undecyl behenate, n-tridecyl behenate, and n-pentadecyl behenate.

[0042] Effective ketones include aliphatic ketones with a total carbon number of 10 or more, such as 2-decanone, 3-decanone, 4-decanone, 2-undecanone, 3-undecanone, 4-undecanone, 5-undecanone, 2-dodecanone, 3-dodecanone, 4-dodecanone, 5-dodecanone, 2-tridecanone, 3-tridecanone, 2-tetradecanone, 2-pentadecanone, 8-pentadecanone, 2-hexadecanone, 3-hexadecanone, 9-heptadecanone, 2-pentadecanone, 2-octadecanone, 2-nonadecanone, 10-nonadecanone, 2-eicosanone, 11-eicosanone, 2-heneicosanone, 2-docosanone, laurone, and stearone. Furthermore, aryl alkyl ketones with a total carbon number of 12 to 24, such as n-octadecanophenone, n-heptadecanophenone, n-hexadecanophenone, n-pentadecanophenone, n-tetradecanophenone, 4-n-dodecacetophenone, n-tridecanophenone, 4-n-undecanoacetophenone, n-laurophenone, 4-n-decanoacetophenone, n-undecanophenone, 4-n-nonylacetophenone, n-decanophenone, 4-n-octylacetophenone, n-nonylacetophenone Examples include nophenone, 4-n-heptylacetophenone, n-octanophenone, 4-n-hexylacetophenone, 4-n-cyclohexylacetophenone, 4-tert-butylpropiophenone, n-heptaphenone, 4-n-pentylacetophenone, cyclohexylphenyl ketone, benzyl-n-butyl ketone, 4-n-butylacetophenone, n-hexanophenone, 4-isobutylacetophenone, 1-acetonaphthone, 2-acetonaphthone, and cyclopentylphenyl ketone.

[0043] As for ethers, aliphatic ethers with a total of 10 or more carbon atoms are effective, and examples include dipentyl ether, dihexyl ether, diheptyl ether, dioctyl ether, dinonyl ether, didecyl ether, diundecyl ether, didodecyl ether, ditridecyl ether, ditetradecyl ether, dipentadecyl ether, dihexadecyl ether, dioctadecyl ether, decanediol dimethyl ether, undecanediol dimethyl ether, dodecanediol dimethyl ether, tridecanediol dimethyl ether, decanediol diethyl ether, and undecanediol diethyl ether.

[0044] Acid amides include acetamide, propionic acid amide, butyrate amide, caproic acid amide, caprylic acid amide, capric acid amide, lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, oleic acid amide, erucic acid amide, benzamide, caproic acid anilide, caprylic acid anilide, capric acid anilide, lauric acid anilide, myristic acid anilide, palmitic acid anilide, stearic acid anilide, behenic acid anilide, oleic acid anilide, erucic acid anilide, caproic acid N-methylamide, Caprylic acid N-methylamide, capric acid N-methylamide, lauric acid N-methylamide, myristate acid N-methylamide, palmitic acid N-methylamide, stearate N-methylamide, behenic acid N-methylamide, oleic acid N-methylamide, erucate N-methylamide, lauric acid N-ethylamide, myristate acid N-ethylamide, palmitic acid N-ethylamide, stearate N-ethylamide, oleic acid N-ethylamide, lauric acid N-butylamide, myristate acid N-butylamide, palmitic acid N-butylamide, stear N-butylamide phosphate, N-butylamide oleate, N-octylamide laurate, N-octylamide myristate, N-octylamide palmitate, N-octylamide stearate, N-octylamide oleate, N-dodecylamide laurate, N-dodecylamide myristate, N-dodecylamide palmitate, N-dodecylamide stearate, N-dodecylamide oleate, dilaurate, dimyristateamide, dipalmitamide, distearate, dioleamide, trilaurate, tri Myristic acid amide, tripalmitic acid amide, tristearic acid amide, trioleic acid amide, succinic acid amide, adipic acid amide, glutaric acid amide, malonic acid amide, azelaic acid amide, maleic acid amide, succinic acid N-methylamide, adipic acid N-methylamide, glutaric acid N-methylamide, malonic acid N-methylamide, azelaic acid N-methylamide, succinic acid N-ethylamide, adipic acid N-ethylamide, glutaric acid N-ethylamide, malonic acid N-ethylamide, azelaic acid N-ethylamide, succinic acid N-butylamide,Examples include N-butylamide adipic acid, N-butylamide glutarate, N-butylamide malonate, N-octylamide adipic acid, and N-dodecylamide adipic acid.

[0045] Furthermore, the compound represented by the following general formula (4) can also be used as component (c). [In the formula, R １ represents a hydrogen atom or a methyl group, m represents an integer from 0 to 2, and X １ , X ２ Either one of them is - (CH ２ ) ｎ OCOR ２ or - (CH ２ ) ｎ COOR ２ The other side represents a hydrogen atom, n represents an integer from 0 to 2, and R ２ Y represents an alkyl or alkenyl group having 4 or more carbon atoms. １ and Y ２ R represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a methoxy group, or a halogen, and r and p represent integers from 1 to 3. Among the compounds represented by formula (4), R １ When R is a hydrogen atom, a reversible thermal color change composition with a wider hysteresis width can be obtained, which is preferable, and further R １ It is more preferable that is a hydrogen atom and m is 0. Of the compounds represented by formula (4), the compound represented by the following general formula (5) is more preferably used. (In the formula, R represents an alkyl group or alkenyl group having 8 or more carbon atoms, preferably an alkyl group having 10 to 24 carbon atoms, and more preferably an alkyl group having 12 to 22 carbon atoms.) Specific examples of the compound include 4-benzyloxyphenylethyl octanoate, 4-benzyloxyphenylethyl nonanoate, 4-benzyloxyphenylethyl decanoate, 4-benzyloxyphenylethyl undecanoate, 4-benzyloxyphenylethyl dodecanoate, 4-benzyloxyphenylethyl tridecanoate, 4-benzyloxyphenylethyl tetradecanoate, 4-benzyloxyphenylethyl pentadecanoate, 4-benzyloxyphenylethyl hexadecanoate, 4-benzyloxyphenylethyl heptadecanoate, and 4-benzyloxyphenylethyl octadecanoate.

[0046] Furthermore, as component (c) above, a compound represented by the following general formula (6) can also be used. (In the formula, R represents an alkyl or alkenyl group having 8 or more carbon atoms, m and n each represent an integer from 1 to 3, and X and Y each represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and a halogen, respectively.) Specifically, examples of the compound include 1,1-diphenylmethyl octanoate, 1,1-diphenylmethyl nonanoate, 1,1-diphenylmethyl decanoate, 1,1-diphenylmethyl undecanoate, 1,1-diphenylmethyl dodecanoate, 1,1-diphenylmethyl tridecanoate, 1,1-diphenylmethyl tetradecanoate, 1,1-diphenylmethyl pentadecanoate, 1,1-diphenylmethyl hexadecanoate, 1,1-diphenylmethyl heptadecanoate, and 1,1-diphenylmethyl octadecanoate.

[0047] Furthermore, the compound represented by the following general formula (7) can also be used as component (c). (In the formula, X represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a methoxy group, or a halogen atom; m represents an integer from 1 to 3; and n represents an integer from 1 to 20.) The compounds include diesters of malonic acid and 2-[4-(4-chlorobenzyloxy)phenyl)]ethanol, diesters of succinic acid and 2-(4-benzyloxyphenyl)ethanol, diesters of succinic acid and 2-[4-(3-methylbenzyloxy)phenyl)]ethanol, diesters of glutaric acid and 2-(4-benzyloxyphenyl)ethanol, diesters of glutaric acid and 2-[4-(4-chlorobenzyloxy)phenyl)]ethanol, diesters of adipic acid and 2-(4-benzyloxyphenyl)ethanol, diesters of pimelic acid and 2-(4-benzyloxyphenyl)ethanol, diesters of suberic acid and 2-(4-benzyloxyphenyl)ethanol, and diesters of suberic acid and 2-[4-(3-methylbenzyl Examples include diesters of xy(phenyl)ethanol, suberic acid and 2-[4-(4-chlorobenzyloxy)phenyl)]ethanol, suberic acid and 2-[4-(2,4-dichlorobenzyloxy)phenyl)]ethanol, azelaic acid and 2-(4-benzyloxyphenyl)ethanol, sebacic acid and 2-(4-benzyloxyphenyl)ethanol, 1,10-decanedicarboxylic acid and 2-(4-benzyloxyphenyl)ethanol, 1,18-octadecanedicarboxylic acid and 2-(4-benzyloxyphenyl)ethanol, and 1,18-octadecanedicarboxylic acid and 2-[4-(2-methylbenzyloxy)phenyl)]ethanol.

[0048] Furthermore, the compound represented by the following general formula (8) can also be used as component (c). (In the formula, R represents an alkyl or alkenyl group having 1 to 21 carbon atoms, and n represents an integer from 1 to 3.) The compound is a diester of 1,3-bis(2-hydroxyethoxy)benzene and capric acid, a diester of 1,3-bis(2-hydroxyethoxy)benzene and undecanoic acid, a diester of 1,3-bis(2-hydroxyethoxy)benzene and lauric acid, a diester of 1,3-bis(2-hydroxyethoxy)benzene and myristic acid, a diester of 1,4-bis(hydroxymethoxy)benzene and butyric acid, a diester of 1,4-bis(hydroxymethoxy)benzene and isovaleric acid, a diester of 1,4-bis(2-hydroxyethoxy)benzene and acetic acid, Examples include diesters of 4-bis(2-hydroxyethoxy)benzene with propionic acid, 1,4-bis(2-hydroxyethoxy)benzene with valeric acid, 1,4-bis(2-hydroxyethoxy)benzene with caproic acid, 1,4-bis(2-hydroxyethoxy)benzene with caprylic acid, 1,4-bis(2-hydroxyethoxy)benzene with capric acid, 1,4-bis(2-hydroxyethoxy)benzene with lauric acid, and 1,4-bis(2-hydroxyethoxy)benzene with myristic acid.

[0049] Furthermore, the compound represented by the following general formula (9) can also be used as component (c). (In the formula, X represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom; m represents an integer from 1 to 3; and n represents an integer from 1 to 20.) Examples of the compound include diesters of succinic acid and 2-phenoxyethanol, diesters of suberic acid and 2-phenoxyethanol, diesters of sebacic acid and 2-phenoxyethanol, diesters of 1,10-decanedicarboxylic acid and 2-phenoxyethanol, and diesters of 1,18-octadecanedicarboxylic acid and 2-phenoxyethanol.

[0050] Furthermore, the compound represented by the following general formula (10) can also be used as component (c). (In the formula, R represents any of a C4 to C22 alkyl group, a cycloalkylalkyl group, a cycloalkyl group, or a C4 to C22 alkenyl group; X represents any of a hydrogen atom, a C1 to C4 alkyl group, a C1 to C4 alkoxy group, or a halogen atom; and n represents 0 or 1.) Examples of the compound include decyl 4-phenylbenzoate, lauryl 4-phenylbenzoate, myristyl 4-phenylbenzoate, cyclohexylethyl 4-phenylbenzoate, octyl 4-biphenylacetate, nonyl 4-biphenylacetate, decyl 4-biphenylacetate, lauryl 4-biphenylacetate, myristyl 4-biphenylacetate, tridecyl 4-biphenylacetate, pentadecyl 4-biphenylacetate, cetyl 4-biphenylacetate, cyclopentyl 4-biphenylacetate, cyclohexylmethyl 4-biphenylacetate, hexyl 4-biphenylacetate, and cyclohexylmethyl 4-biphenylacetate.

[0051] Furthermore, the compound represented by the following general formula (11) can also be used as component (c). (In the formula, R represents any alkyl group having 3 to 18 carbon atoms or an aliphatic acyl group having 3 to 18 carbon atoms; X represents any hydrogen atom, any alkyl group having 1 to 3 carbon atoms, any alkoxy group having 1 or 2 carbon atoms, or any halogen atom; Y represents any hydrogen atom or any methyl group; and Z represents any hydrogen atom, any alkyl group having 1 to 4 carbon atoms, any alkoxy group having 1 or 2 carbon atoms, or any halogen atom.) Examples of the compound include phenoxyethyl 4-butoxybenzoate, phenoxyethyl 4-pentyloxybenzoate, phenoxyethyl 4-tetradecyloxybenzoate, an ester of phenoxyethyl 4-hydroxybenzoate and dodecanoic acid, and a dodecyl ether of phenoxyethyl vanillate.

[0052] Furthermore, the compound represented by the following general formula (12) can also be used as component (c). (In the formula, R represents any of an alkyl group having 4 to 22 carbon atoms, an alkenyl group having 4 to 22 carbon atoms, a cycloalkylalkyl group, or a cycloalkyl group; X represents any of a hydrogen atom, an alkyl group, an alkoxy group, or a halogen atom; Y represents any of a hydrogen atom, an alkyl group, an alkoxy group, or a halogen atom; and n represents 0 or 1.) Examples of the compound include the benzoic acid ester of octyl p-hydroxybenzoate, the benzoic acid ester of decyl p-hydroxybenzoate, the p-methoxybenzoic acid ester of heptyl p-hydroxybenzoate, the o-methoxybenzoic acid ester of dodecyl p-hydroxybenzoate, and the benzoic acid ester of cyclohexylmethyl p-hydroxybenzoate.

[0053] Furthermore, the compound represented by the following general formula (13) can also be used as component (c). (In the formula, R represents any of an alkyl group having 3 to 18 carbon atoms, a cycloalkylalkyl group having 6 to 11 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, or an alkenyl group having 3 to 18 carbon atoms; X represents any of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, or a halogen atom; and Y represents any of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a methoxy group, an ethoxy group, or a halogen atom.) Examples of the compound include phenoxyethyl ether of nonyl p-hydroxybenzoate, phenoxyethyl ether of decyl p-hydroxybenzoate, phenoxyethyl ether of undecyl p-hydroxybenzoate, and phenoxyethyl ether of dodecyl vanillate.

[0054] Furthermore, the compound represented by the following general formula (14) can also be used as component (c). (In the formula, R represents a cycloalkyl group having 3 to 8 carbon atoms or a cycloalkylalkyl group having 4 to 9 carbon atoms, and n represents an integer from 1 to 3.) Examples of the compound include a diester of 1,3-bis(2-hydroxyethoxy)benzene and cyclohexanecarboxylic acid, a diester of 1,4-bis(2-hydroxyethoxy)benzene and cyclohexanepropionic acid, and a diester of 1,3-bis(2-hydroxyethoxy)benzene and cyclohexanepropionic acid.

[0055] Furthermore, the compound represented by the following general formula (15) can also be used as component (c). (In the formula, R represents an alkyl group having 3 to 17 carbon atoms, a cycloalkyl group having 3 to 8 carbon atoms, or a cycloalkylalkyl group having 5 to 8 carbon atoms; X represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a methoxy group, an ethoxy group, or a halogen atom; and n represents an integer from 1 to 3.) Examples of the compound include diesters of 4-phenylphenol ethylene glycol ether and cyclohexanecarboxylic acid, diesters of 4-phenylphenol diethylene glycol ether and lauric acid, diesters of 4-phenylphenol triethylene glycol ether and cyclohexanecarboxylic acid, diesters of 4-phenylphenol ethylene glycol ether and octanoic acid, diesters of 4-phenylphenol ethylene glycol ether and nonanoic acid, diesters of 4-phenylphenol ethylene glycol ether and decanoic acid, and diesters of 4-phenylphenol ethylene glycol ether and myristic acid.

[0056] Furthermore, it is also possible to use specific alkoxyphenol compounds having linear or side-chain alkyl groups with 3 to 18 carbon atoms as electron-accepting compounds (Japanese Patent Publication No. 11-129623, Japanese Patent Publication No. 11-5973), specific hydroxybenzoic acid esters (Japanese Patent Publication No. 2001-105732), gallic acid esters, etc. (Japanese Patent Publication No. 51-44706, Japanese Patent Publication No. 2003-253149), or reversible thermochromic compositions of the heat-developing type (developing color upon heating and decolorizing upon cooling) (see Figure 3).

[0057] The reversible thermochromic composition according to this disclosure is a compatible mixture comprising the above-mentioned components (a), (b), and (c) as essential components. The proportion of each component depends on the concentration, discoloration temperature, discoloration form, and type of each component, but generally, the component ratios that yield the desired properties are in the range of 1 part of component (a) to 0.1 to 100 parts of component (b), preferably 0.1 to 50 parts, more preferably 0.5 to 20 parts, and 1 to 800 parts of component (c), preferably 5 to 200 parts, more preferably 5 to 100 parts, and even more preferably 10 to 100 parts (all of the above proportions are in parts by mass). By having the mass ratio of components (a), (b), and (c) within the above range, it is easy to obtain a reversible thermochromic composition that exhibits high concentration in the colored state and low residual color in the decolorized state, that is, a composition that is even better in terms of contrast between the colored state and the decolorized state.

[0058] Furthermore, various light stabilizers may be added as needed. The light stabilizers are included to prevent photodegradation of the reversible thermochromic composition consisting of components (a), (b), and (c), and are included in a ratio of 0.3 to 24% by mass, preferably 0.3 to 16% by mass, per 1% by mass of component (a). Among the light stabilizers, ultraviolet absorbers can effectively cut ultraviolet rays contained in sunlight, etc., and prevent photodegradation caused by the excitation state due to the photoreaction of component (a), while antioxidants, singlet oxygen quenchers, superoxide anion quenchers, ozone quenchers, etc., can suppress oxidation reactions caused by light. The light stabilizers may be used alone or in combination of two or more types. In addition, by blending the reversible thermochromic composition with non-coloring colorants such as general dyes or pigments, it is possible to make it exhibit a color change behavior from colored (1) to colored (2).

[0059] The reversible thermochromic composition according to this disclosure is effective when applied as is, but it can also be encapsulated in microcapsules to form reversible thermochromic microcapsule pigments (hereinafter sometimes referred to as "microcapsule pigments"), or dispersed in a thermoplastic resin or thermosetting resin to form reversible thermochromic resin particles (hereinafter sometimes referred to as "resin particles"). The reversible thermochromic composition is preferably encapsulated in microcapsules to form reversible thermochromic microcapsule pigments. This is because encapsulation in microcapsules allows for the formation of chemically or physically stable pigments, and furthermore, the reversible thermochromic composition maintains the same composition and exhibits the same effects under various usage conditions. Microencapsulation methods include conventionally known interfacial polymerization methods for isocyanates, in Situ polymerization methods such as melamine-formaldehyde systems, liquid curing coating methods, phase separation methods from aqueous solutions, phase separation methods from organic solvents, melt-dispersion-cooling methods, air suspension coating methods, spray drying methods, etc., and can be appropriately selected depending on the application. Furthermore, depending on the purpose, a secondary resin coating can be applied to the surface of the microcapsules to provide durability or modify the surface properties for practical use. The microcapsule pigment preferably has a mass ratio of encapsulated material to wall film of 7:1 to 1:1. This range prevents a decrease in color density and vividness during color development. More preferably, the mass ratio of encapsulated material to wall film is 6:1 to 1:1.

[0060] The average particle size of microcapsule pigments or resin particles is preferably in the range of 0.01 to 50 μm, more preferably 0.1 to 30 μm, and even more preferably 0.5 to 20 μm. If the average particle size exceeds 50 μm, dispersion stability and processability are poor when blending into liquid compositions or resins. On the other hand, if the average particle size is less than 0.01 μm, it becomes difficult to exhibit high-concentration color development. When microcapsule pigments or resin particles are used in ink compositions for writing instruments, the average particle size is preferably in the range of 0.01 to 5 μm, preferably 0.05 to 4 μm, more preferably 0.1 to 3 μm, and even more preferably 0.5 to 3 μm. If the average particle size exceeds 5 μm, it becomes difficult to obtain good ink discharge performance when used in writing instruments. On the other hand, if the average particle size is less than 0.01 μm, it becomes difficult to exhibit high-concentration color development.

[0061] The average particle diameter is measured by determining the particle area using image analysis particle size distribution software [Mountec Co., Ltd., product name: MacView], calculating the projected area circle equivalent diameter (Heywood diameter) from the area of ​​the particle area, and measuring the average particle diameter of particles equivalent to an equivolute sphere based on that value. If the particle diameter of all or most of the particles exceeds 0.2 μm, it is also possible to measure the average particle diameter of particles equivalent to an equivolute sphere using the Coulter method with a particle size distribution analyzer [Beckman Coulter, Inc., product name: Multisizer 4e]. Furthermore, based on the values ​​measured using the above software or the Coulter method analyzer, the volume-based particle diameter and average particle diameter may be measured using a calibrated laser diffraction / scattering particle size distribution analyzer (device name: LA-960V2, Horiba, Ltd.).

[0062] The aforementioned reversible thermochromic composition, microcapsule pigment, or resin particles can be dispersed in a vehicle containing additives as needed to form a liquid composition which can then be used in printing inks for screen printing, offset printing, process printing, gravure printing, coaters, and pad printing; paints for brush painting, spray painting, electrostatic painting, electrodeposition painting, flow painting, roller painting, and dipping painting; inks for writing instruments such as marking pens, ballpoint pens, fountain pens, and brush pens; inks for applicators; stamp inks; inkjet inks; UV-curing inks; paints; cosmetics; and textile colorants.

[0063] Additives include resins, crosslinking agents, curing agents, drying agents, plasticizers, viscosity modifiers, dispersants, UV absorbers, infrared absorbers, antioxidants, light stabilizers, solubilizers, anti-settling agents, smoothing agents, gelling agents, defoaming agents, matting agents, penetrating agents, pH adjusters, foaming agents, coupling agents, humectants, antifungal agents, preservatives, rust inhibitors, and the like.

[0064] Examples of vehicles for the liquid composition include oily vehicles containing organic solvents, or aqueous vehicles containing water and, if necessary, organic solvents. Examples of organic solvents include ethanol, propanol, butanol, glycerin, sorbitol, triethanolamine, diethanolamine, monoethanolamine, ethylene glycol, diethylene glycol, thiodiethylene glycol, polyethylene glycol, propylene glycol, butylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, sulforane, 2-pyrrolidone, N-methyl-2-pyrrolidone, and the like.

[0065] When the liquid composition is a writing instrument ink composition, examples include a shear viscosity reducing ink containing a shear viscosity reducing agent, and a coagulating ink containing a water-soluble polymer flocculant to suspend microcapsule pigments in a loosely aggregated state. By adding the shear viscosity reducing agent, the aggregation and sedimentation of microcapsule pigments and resin particles can be suppressed, and the bleeding of the writing can be suppressed, thus forming good writing. Furthermore, when the writing instrument filled with the ink composition is in the form of a ballpoint pen, it is possible to prevent ink leakage from the gap between the ball and the tip when not in use, and to prevent ink backflow when the writing tip is left upright. The shear-thickening agent may be xanthan gum, gellan gum, succinoglycans (average molecular weight approximately 1 to 8 million) whose constituent monosaccharides are organic acid-modified heteropolysaccharides of glucose and galactose, guar gum, locust bean gum and its derivatives, hydroxyethylcellulose, alkyl alginates, polymers with a molecular weight of 100,000 to 150,000 mainly composed of alkyl esters of methacrylic acid, glucomannan, gelling polysaccharides extracted from seaweed such as agar and carrageenan, benzylidene sorbitol and benzylidene xylitol or their derivatives, crosslinkable acrylic acid polymers, inorganic fine particles, polyglycerin fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyethylene glycol fatty acid esters, polyoxyethylene alkyl ethers, polyoxypropylene alkyl ethers, polyoxyethylene alkylphenyl ethers, nonionic surfactants with an HLB value of 8 to 12 such as fatty acid amides, or salts of dialkyl or dialkenyl sulfosuccinate. Examples include a mixture of N-alkyl-2-pyrrolidone and an anionic surfactant, and a mixture of polyvinyl alcohol and an acrylic resin.

[0066] Examples of the aforementioned water-soluble polymer flocculants include polyvinylpyrrolidone, polyethylene oxide, and water-soluble polysaccharides. Examples of the aforementioned water-soluble polysaccharides include tragacanth gum, guar gum, pullulan, cyclodextrin, and water-soluble cellulose derivatives. Specific examples of water-soluble cellulose derivatives include methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxyethylmethylcellulose, and hydroxypropylmethylcellulose. In writing instrument ink compositions, any water-soluble polymer that exhibits a loose bridging effect between microcapsule pigment particles can be applied, but water-soluble cellulose derivatives are particularly effective.

[0067] Furthermore, adding a water-soluble resin can impart adhesion and viscosity to the paper surface. Examples of the water-soluble resin include alkyd resin, acrylic resin, styrene-maleic acid copolymer, cellulose derivative, polyvinylpyrrolidone, polyvinyl alcohol, and dextrin, with polyvinyl alcohol being preferred. Moreover, partially saponified polyvinyl alcohol with a degree of saponification of 70 to 89 mol% is more preferably used because it is highly soluble even in acidic inks. The amount of the water-soluble resin added to the ink is in the range of 0.3 to 3.0% by mass, preferably 0.5 to 1.5% by mass.

[0068] Furthermore, when the ink composition is used by filling it into a ballpoint pen, it is preferable to add a lubricant such as a higher fatty acid like oleic acid, a nonionic surfactant having a long-chain alkyl group, a polyether-modified silicone oil, thiophosphite triesters such as thiophosphite tri(alkoxycarbonylmethyl ester) or thiophosphite tri(alkoxycarbonylethyl ester), phosphate monoesters of polyoxyethylene alkyl ether or polyoxyethylene alkylaryl ether, phosphate diesters of polyoxyethylene alkyl ether or polyoxyethylene alkylaryl ether, or metal salts, ammonium salts, amine salts, or alkanolamine salts thereof to prevent wear of the ball bearing seat. Furthermore, pH adjusters such as inorganic salts like sodium carbonate, sodium phosphate, and sodium acetate, and organic basic compounds such as water-soluble amine compounds, rust inhibitors such as benzotriazole, tolyltriazole, dicyclohexylammonium nitride, diisopropylammonium nitride, and saponins, preservatives or fungicides such as carbolic acid, sodium salt of 1,2-benzthiazolin 3-one, sodium benzoate, sodium dehydroacetate, potassium sorbate, propyl parahydroxybenzoate, and 2,3,5,6-tetrachloro-4-(methylsulfonyl)pyridine may be added. Additionally, urea, nonionic surfactants, reduced or non-reduced starch hydrolysates, oligosaccharides such as trehalose, sucrose, cyclodextrin, glucose, dextrin, sorbitol, mannitol, and sodium pyrophosphate may be added as wetting agents, defoamers, dispersants, and fluorinated surfactants or nonionic surfactants to improve ink penetration.

[0069] The aforementioned ink composition for writing instruments is used by filling it into writing instruments such as ballpoint pens and marking pens, which have a ballpoint pen tip or marking pen tip attached to the writing end.

[0070] When filling a ballpoint pen, the structure and shape of the ballpoint pen itself are not particularly limited. For example, one could exemplified a ballpoint pen having an ink reservoir filled with shear-reducing ink inside the barrel, the ink reservoir communicating with a tip to which a ball is attached, and a liquid stopper (ink follower) for preventing backflow closely attached to the end face of the ink.

[0071] To describe the ballpoint pen tip in more detail, the tip can be made by holding a ball in a ball-holding portion formed by pressing the tip of a metal pipe inward from the outer surface, or by holding a ball in a ball-holding portion formed by cutting a metal material with a drill or the like, or by providing a resin ball seat inside a metal or plastic tip, or by biasing the ball held in the tip forward with a spring. The ball can be made of cemented carbide, stainless steel, ruby, ceramic, resin, rubber, etc., and has a diameter of about 0.3 to 3.0 mm, preferably 0.3 to 1.5 mm, more preferably 0.4 to 1.0 mm.

[0072] The ink reservoir tube containing the ink is, for example, a molded body made of a thermoplastic resin such as polyethylene, polypropylene, polyethylene terephthalate, or nylon. The tip may be directly connected to the ink reservoir tube, or the ink reservoir tube and the tip may be connected via a connecting member. The ink reservoir tube may be in the form of a refill, with the refill housed inside the barrel, or the barrel itself, with the tip attached to the end, may be used as the ink reservoir, and the ink composition may be directly filled into the barrel. The ballpoint pen obtained in this manner may be a ballpoint pen with a cap, or it may be a retractable ballpoint pen, and its shape is not particularly limited. Any retractable ballpoint pen can be used as long as the writing tip provided on the ballpoint pen refill is housed inside the barrel with the tip exposed to the outside air, and the writing tip protrudes from the barrel opening when the retractable mechanism is operated. Examples of operating methods for the retractable mechanism include a knock type, a twist type, a slide type, etc. The aforementioned knock-type pen has a knock mechanism at the rear end or side of the barrel, and the ballpoint pen tip extends and retracts from the front end opening of the barrel by pressing the knock mechanism, or the ballpoint pen tip extends and retracts from the front end opening of the barrel by pressing a clip provided on the barrel. The aforementioned rotary-type pen has a rotating mechanism at the rear of the barrel, and the ballpoint pen tip extends and retracts from the front end opening of the barrel by rotating the rotating mechanism. The aforementioned slide-type pen has a slide mechanism on the side of the barrel, and the ballpoint pen tip extends and retracts from the front end opening of the barrel by operating the slide, or the ballpoint pen tip extends and retracts from the front end opening of the barrel by sliding a clip provided on the barrel.

[0073] In one embodiment, a refill containing the reversible thermochromic liquid composition of the present disclosure is provided. In one embodiment, a writing instrument is provided, the refill housed in a barrel. The refill can be formed by connecting a tip directly or via a connecting member to an ink reservoir tube, and filling the ink reservoir tube with ink and, if necessary, an ink backflow prevention body described later. A writing instrument can be formed by housing the refill in a barrel, and when the ink in the refill runs out due to writing, the writing instrument can be used repeatedly by replacing it with a new refill.

[0074] An ink backflow prevention body can be filled into the rear end of the ink composition contained in the ink storage tube. The ink backflow prevention body composition consists of a non-volatile liquid or a low-volatility liquid. Specifically, examples include petrolatum, spindle oil, castor oil, olive oil, refined mineral oil, liquid paraffin, polybutene, α-olefin, α-olefin oligomer or co-oligomer, dimethyl silicone oil, methylphenyl silicone oil, amino-modified silicone oil, polyether-modified silicone oil, fatty acid-modified silicone oil, etc., and one or more of these can be used in combination.

[0075] The non-volatile liquid and / or non-volatile liquid is preferably thickened to a suitable viscosity by adding a thickening agent. Examples of the thickening agent include silica with a hydrophobic surface treatment, fine particle silica with a methylated surface treatment, aluminum silicate, swollen mica, clay-based thickening agents such as hydrophobic treated bentonite and montmorillonite, fatty acid metal soaps such as magnesium stearate, calcium stearate, aluminum stearate, and zinc stearate, tripenzylidene sorbitol, fatty acid amides, amide-modified polyethylene wax, hydrogenated castor oil, dextrin compounds such as fatty acid dextrin, and cellulose compounds. Furthermore, the liquid ink backflow prevention body and the solid ink backflow prevention body can be used in combination.

[0076] Furthermore, when filling a marking pen with an ink composition for writing instruments, the structure and shape of the marking pen itself are not particularly limited. For example, a marking pen may have an ink-absorbing body made of a fiber bundle built into the barrel, and a pen tip made of a fiber processed body with capillary gaps attached to the barrel directly or via an intermediate member, with the ink-absorbing body and the pen tip connected, and the ink-absorbing body of the marking pen being impregnated with a cohesive ink. Another example is a marking pen in which the pen tip and an ink-storage tube are arranged via a valve that is released when the pen tip is pressed, and the ink is directly stored in the ink-storage tube.

[0077] The pen tip is a porous material with interconnected pores, selected from materials such as resin-processed fibers, fused heat-meltable fibers, or felt, with a porosity of approximately 30-70%. One end is processed into a shape suitable for the purpose, such as a bullet shape, rectangle, or chisel shape, for practical use. The ink-absorbing body is made of crimped fibers bundled in the longitudinal direction, and is contained within a covering such as a plastic cylinder or film, with the porosity adjusted to approximately 40-90%. The valve can be of the pumping type, but one with a spring pressure that can be released by pen pressure is preferable. The marking pen obtained as described above may be a marking pen with a cap, or a retractable marking pen, and its shape is not particularly limited.

[0078] Furthermore, the form of the ballpoint pen or marking pen is not limited to those described above, and may also be a multi-function writing instrument (such as a double-ended or retractable-tip type) equipped with pen tips of different shapes or pen tips that dispense inks of different colors.

[0079] The writing produced by a writing instrument containing the aforementioned ink composition can be discolored by friction with a finger or by applying a heating or cooling device. Examples of heating devices include electrically heated discoloration devices equipped with resistance heating elements, heated discoloration devices filled with hot water, etc., and the use of a hair dryer. Preferably, a friction member or friction body that can be discolored by a simple method is used. The friction member or friction body is preferably an elastic material such as an elastomer or plastic foam that is highly elastic and can generate frictional heat by creating appropriate friction when rubbed, but it may also be a plastic molded body, stone, wood, metal, or cloth. It is also possible to rub the writing with an eraser, but since eraser residue is generated when rubbing is performed, it is preferable to use the friction member or friction body described above. As the material for the friction member or friction body, silicone resin, SEBS resin (styrene-ethylene-butadiene-styrene block copolymer), and polyester resin are preferably used. However, silicone resin tends to adhere to the erased area, and the writing tends to be repelled when writing repeatedly, so SEBS resin and polyester resin are more preferably used. The friction member may be a separate component (friction body) of any shape from the writing instrument, but attaching it to the writing instrument provides excellent portability. In the case of a writing instrument with a cap, the location where the friction member is provided is not particularly limited, but for example, the cap itself may be formed from the friction member, the barrel itself may be formed from the friction member, the clip itself may be formed from the friction member if a clip is provided, or the friction member may be provided at the tip (top) of the cap or the rear end of the barrel (the part without a writing tip). In the case of retractable writing instruments, the location where the friction element is provided is not particularly limited, but for example, the barrel itself may be formed from the friction element, or if a clip is provided, the clip itself may be formed from the friction element, or the friction element may be provided near the barrel opening, at the rear end of the barrel (the part without the writing tip), or at the knock mechanism. Examples of heating and cooling devices include heating and cooling devices that use a Peltier element, heating and cooling devices filled with a refrigerant such as cold water or ice chips, and the application of refrigerators or freezers. Furthermore, a writing instrument set can be obtained by combining the writing instrument and the friction element.

[0080] The reversible thermochromic composition, microcapsule pigment, or resin particles can be melt-blended with an excipient and molded to form a solid molded body for application, which can then be used as a solid writing instrument or solid cosmetic. Examples of solid writing instruments include crayons, pencil leads, mechanical pencil leads, and solid gel markers. Examples of solid cosmetic products include foundations, eyeliners, eyebrow pencils, eyeshadows, and lipsticks. Examples of excipients used in solid writing instruments include waxes, gelling agents, and clay minerals. Among these excipients, it is preferable to include at least one selected from the group consisting of polyolefin wax, sucrose fatty acid esters, and dextrin fatty acid esters, as these easily improve the density of the writing. In addition, the solid writing instrument may contain other additives as needed, such as fillers, binder resins, viscosity modifiers, preservatives or antifungal agents, antibacterial agents, antioxidants, UV inhibitors, lubricants, and fragrances.

[0081] The aforementioned reversible thermochromic composition, microcapsule pigment, or resin particles can be melt-blended with thermoplastic resins, thermosetting resins, waxes, etc., to form pellets, powders, or pastes, which can then be used as a molding resin composition. Using this molding resin composition, molded articles in the form of three-dimensional objects, films, sheets, plates, filaments, rods, pipes, etc., of any shape can be obtained by general-purpose injection molding, extrusion molding, blow molding, casting, etc. Furthermore, toners and powder coatings can be obtained by melt-blending with thermoplastic resins.

[0082] The reversible thermochromic composition, microcapsule pigment, or resin particles can be combined with a support to form a laminate comprising a reversible thermochromic layer containing microcapsule pigment and a support. Specifically, the reversible thermochromic composition, microcapsule pigment, or resin particles can be dispersed in a medium containing a binder, which is a film-forming material, and applied as a reversible thermochromic material such as an ink or paint. A reversible thermochromic layer can then be formed on a support such as paper, synthetic paper, fabric, flocked or napped fabric, nonwoven fabric, synthetic leather, leather, plastic, glass, ceramics, wood, or stone to obtain a laminate.

[0083] By incorporating non-coloring colorants such as general dyes or pigments into the above-mentioned liquid composition, solid molded body for coating, and resin composition for molding, it is possible to obtain a material that exhibits a color change behavior from colored (1) to colored (2).

[0084] Examples of products using reversible thermochromic compositions, microencapsulated pigments, or resin particles include the following: (1) Toys: Dolls and animal-shaped toys, hair for dolls and animal-shaped toys, dollhouses and furniture, clothing, hats, bags, shoes and other doll accessories, accessory toys, stuffed animals, drawing toys, toy picture books, jigsaw puzzles and other puzzle toys, building blocks, block toys, clay toys, flowing toys, spinning tops, kites, musical instrument toys, cooking toys, gun toys, capture toys, background toys, toys that imitate vehicles, animals, plants, buildings, food, etc. (2) Clothing: Clothing such as T-shirts, sweatshirts, blouses, dresses, swimwear, raincoats, and ski wear; footwear such as shoes; shoelaces; insoles, outsoles, midsoles and other shoe components; cloth personal items such as handkerchiefs, towels, and furoshiki; gloves; ties; hats; sportswear, etc. (3) Indoor decorations: Carpets, curtains, curtain cords, tablecloths, rugs, cushions, seat cushions, chair upholstery, seats, mats, picture frames, artificial flowers, photo frames, etc. (4) Furniture: Bedding such as futons, pillows, and mattresses; chairs; floor chairs; sofas; lighting fixtures; heating and cooling appliances, etc. (5) Jewelry: Rings, bracelets, tiaras, necklaces, earrings, hair clips, false nails, ribbons, scarves, watches, glasses, keychains, etc. (6) Stationery: Writing instruments, stamps, erasers, rulers, notebooks, diaries, adhesive tape, etc. (7) Daily necessities: Toiletries such as disposable diapers; bath products; toothbrushes; insulated bags; hand warmers; thermometers; watering cans; buckets; cleaning supplies; cosmetics such as lipstick, eyeshadow, foundation, eyeliner, eyebrow products, nail polish, hair dye, and false nail polish. (8) Kitchenware: Cooking utensils, lunch boxes, water bottles, cups, plates, chopsticks, spoons, forks, pots, frying pans, coasters, pot holders, placemats, etc. (9) Other items include calendars, labels, cards, recording materials, various anti-counterfeiting printed materials; books such as picture books; sports equipment such as gloves, protectors, and nets; bags; packaging containers; embroidery thread; fishing gear; musical instruments; cooling packs; pouches such as wallets; umbrellas; vehicles; buildings; temperature sensing indicators; training materials such as picture books and maps; pet supplies; medical or nursing care products such as supporters, bandages, and adhesive plasters; electronic devices such as smartphones, earphones, and speakers.

[0085] The disclosure includes the following: [1] a reversible thermochromic composition comprising at least (a) a fluorane derivative represented by the following general formula (1) as an electron-donating chromogenic organic compound, (b) an electron-accepting compound, and (c) a reaction medium that reversibly causes the electron transfer reaction by components (a) and (b) to occur in a specific temperature range. [In general formula (1), R １１ and R １３ R independently represents an alkyl group which may have substituents, １２ and R １４ R represents a group that is independently represented by the following general formula (2), １５ R represents a halogen atom, an optionally substituted alkyl group, or an optionally substituted alkoxy group, and a represents an integer from 0 to 4. If a represents an integer from 2 to 4, then multiple R １５ They may be the same or different. In general formula (2), R ２１ and R ２２ R independently represents an alkyl group which may have substituents, b represents an integer from 1 to 4, and if b represents an integer from 2 to 4, then multiple R ２２ [2] R in general formula (1) １１ and R １３ The compound according to [1], wherein each of the following groups is independently an alkyl group having 6 to 12 carbon atoms, which may have substituents, or a group represented by the following general formula (3). [In general formula (3), R ３１ This includes a halogen atom, an optionally substituted alkyl group, an optionally substituted alkoxy group, and -C(O)-R ３２ , -C(O)-OR ３３ , -O-C(O)-R ３４ , -SO ２ -R ３５ , represents a nitro group or a cyano group, R ３２ , R ３３ and R ３４R independently represents a hydrogen atom, an optionally substituted alkyl group, or an optionally substituted aryl group. ３５ R represents a hydroxyl group, an optionally substituted alkyl group, or an optionally substituted aryl group; L represents an optionally substituted alkylene group; c represents an integer from 0 to 5; and if c represents an integer from 2 to 5, there are multiple R ３１ [3] In general formula (1), R １１ and R １３ These are, independently of each other, an alkyl group having 6 to 12 carbon atoms, or a group represented by the general formula (3), where R ３１ This includes halogen atoms, C1-C6 alkyl groups, C1-C6 alkoxy groups, and -C(O)-R ３２ , -C(O)-OR ３３ , -O-C(O)-R ３４ , -SO ２ -R ３５ , represents a nitro group or a cyano group, R ３２ , R ３３ and R ３４ Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms which may have substituents, or an aryl group having 6 to 12 carbon atoms which may have substituents, R ３５ R represents a hydroxyl group, an optionally substituted C1-C6 alkyl group, or an optionally substituted C6-C12 aryl group; L represents a C1-C4 alkylene group; c represents an integer from 0 to 2; if c is 2, then two R ３１ The reversible thermochromic composition described in [1] or [2], where R may be the same or different. [4] In general formula (2), R ２１ and R ２２ Each of the following independently represents an alkyl group having 1 to 6 carbon atoms, and b represents an integer from 1 to 3. If b represents an integer from 2 to 3, then multiple R ２２ The reversible thermochromic composition described in any of [1] to [3], where R may be the same or different. [5] In general formula (1), R １１ and R １３These are groups that are independently represented by the general formula (3), and R １５ R is a halogen atom, a C1-C4 alkyl group, or a C1-C4 alkoxy group, where a is an integer from 0 to 1, and in general formula (2), R ２１ and R ２２ R represents an alkyl group with 1 to 4 carbon atoms, and b represents an integer from 1 to 2. When b represents 2, two R ２２ They may be the same or different, and in general formula (3), R ３１ represents a halogen atom, a cyano group, or an alkyl group having 1 to 4 carbon atoms; L represents an alkylene group having 1 to 2 carbon atoms; c represents an integer from 1 to 2; if c represents 2, then two R ３１ [1] to [4] is a reversible thermochromic composition, wherein the two components may be the same or different. [6] A reversible thermochromic composition according to any one of [1] to [5], comprising 0.1 to 100 parts by mass of component (b) and 1 to 800 parts by mass of component (c) per 1 part by mass of component (a). [7] A reversible thermochromic microcapsule pigment containing the reversible thermochromic composition according to any one of [1] to [6]. [8] A reversible thermochromic liquid composition comprising the reversible thermochromic microcapsule pigment according to [7] and a vehicle. [9] A reversible thermochromic liquid composition according to [8], selected from the group consisting of printing inks, writing instrument inks, applicator inks, stamp inks, inkjet inks, paints, UV-curable inks, paints, cosmetics, and textile colorants. A reversible thermochromic molding resin composition comprising the reversible thermochromic microcapsule pigment described in

[10] and [7] and a molding resin. A reversible thermochromic molded article obtained by molding the reversible thermochromic molding resin composition described in

[11] and

[10] . A reversible thermochromic laminate comprising a support and a reversible thermochromic layer comprising the reversible thermochromic microcapsule pigment described in [7].

[0086] Examples are shown below. In the examples, parts refer to parts by mass. Example 1 Preparation of a reversible thermochromic composition (a) 1 part of a fluorane derivative (compound 2 in the table), (b) 5 parts of 1,1-bis(4'-hydroxyphenyl)n-decane and 4 parts of 2,2-bis(4'-hydroxyphenyl)hexafluoropropane, and (c) 25 parts of myristyl alcohol and 25 parts of butyl stearate were mixed and heated to dissolve, and a reversible thermochromic composition that changes from fluorescent pink to colorless was obtained. The complete color development temperature (t) of the reversible thermochromic composition １ ) is 7℃, color development start temperature (t ２ ) is 12℃, decolorization start temperature (t ３ ) is 10℃, and the complete discoloration temperature (t ４ The temperature was 15°C, and the hysteresis width (ΔH) was 3°C.

[0087] Examples 2 to 17 Preparation of Reversible Thermochromic Microcapsule Pigments Reversible thermochromic compositions were prepared using the same method as in Example 1 with components (a), (b), and (c) shown in the following table, and a microcapsule pigment suspension encapsulated in microcapsules was obtained by interfacial polymerization. The pigment was isolated from the microcapsule pigment suspension by centrifugation to obtain a reversible thermochromic microcapsule pigment with an average particle size of 2 μm. In the table, component (a) indicates the compound number as in Example 1, and the number in parentheses indicates parts by mass.

[0088]

[0089] Comparative Example 1 Preparation of a Reversible Thermochromic Composition (a) 1 part of spiro[5H-(1)benzopyrano(2,3-d)pyrimidine-5,1′(3′H)isobenzofuran]-3′-one,2-(dimethylamino)-8-(dimethylamino)-4-methyl-, (b) 4 parts of 1,1-bis(4′-hydroxyphenyl)n-decane and 4 parts of 2,2-bis(4′-hydroxyphenyl)hexafluoropropane, (c) 25 parts of myristyl alcohol and 25 parts of butyl stearate were mixed and heated to dissolve, obtaining a reversible thermochromic composition that changed color from pink to colorless. The complete color development temperature (t) of the above reversible thermochromic composition １ ) is 7℃, color development start temperature (t２ ) is 11℃, decolorization start temperature (t ３ ) is 9℃, the complete discoloration temperature (t ４ The temperature was 15°C, and the hysteresis width (ΔH) was 3°C.

[0090] Comparative Examples 2 to 4 Preparation of Reversible Thermochromic Microcapsule Pigments Reversible thermochromic compositions were prepared using the same method as in Comparative Example 1 with components (a), (b), and (c) shown in the following table, and a microcapsule pigment suspension encapsulated in microcapsules was obtained by interfacial polymerization. The pigment was isolated from the microcapsule pigment suspension by centrifugation to obtain a reversible thermochromic microcapsule pigment with an average particle size of 2 μm. The numbers in parentheses in the table represent parts by mass.

[0091]

[0092] For the preparation of the measurement samples, 40 parts of the reversible thermochromic microcapsule pigments from Examples 2 to 17 and Comparative Examples 2 to 4 were uniformly dispersed in an aqueous ink vehicle consisting of 50 parts of ethylene-vinyl acetate resin emulsion, 1 part of leveling agent, 1 part of defoaming agent, 0.5 parts of viscosity modifier, and 7.5 parts of water to prepare a reversible thermochromic ink. A solid pattern was screen printed on high-quality paper using the ink to obtain the measurement sample.

[0093] Measurement of Hysteresis Characteristics The sample to be measured was placed in the measurement section of a colorimeter (TC-3600 colorimeter, manufactured by Tokyo Denshoku Co., Ltd.), and the sample section was heated and cooled at a rate of 2°C / min. The lightness value was measured as the color density at each temperature, and a color density-temperature curve was created. From the color density-temperature curve, t １ ,t ２ ,t ３ ,t ４ ΔH was calculated. The test results are shown in the table below.

[0094] The reversible thermochromic compositions of Examples 6, 7, 11, 13, 14, and 17 exhibited a highly fluorescent pink color during development and showed very little residual color during decolorization, resulting in excellent color contrast.

[0095] Application Example 1: Preparation of a Reversible Thermochromic Miniature Car A reversible thermochromic spray paint was obtained by stirring and mixing 15 parts of the reversible thermochromic microcapsule pigment prepared in Example 6, 40 parts of a 50% acrylic resin / xylene solution, 20 parts of xylene, 20 parts of methyl isobutyl ketone, and 5 parts of a polyisocyanate-based curing agent in a vehicle. The reversible thermochromic spray paint was spray-painted onto the entire body of a white miniature car and dried to create a reversible thermochromic layer, thereby obtaining a reversible thermochromic miniature car (toy). At room temperature (25°C), the reversible thermochromic layer of the miniature car became a highly fluorescent pink, and when immersed in 39°C hot water, it turned white. When removed from the hot water and left at room temperature (25°C), it became a highly fluorescent pink again, and the above behavior could be repeated.

[0096] Application Example 2: Preparation of a Reversible Thermochromic Mug In Example 7, 30 parts of reversible thermochromic microcapsule pigment, 60 parts of hard liquid epoxy resin, 2 parts of ultraviolet absorber, 2 parts of thixotropy agent, and 0.5 parts of defoamer were mixed, and 40 parts of room-temperature curing aliphatic polyamine were added to obtain a reversible thermochromic epoxy ink. Using the reversible thermochromic epoxy ink, a heart pattern was printed on the side of a ceramic mug using a curved surface printing machine with a stainless steel screen plate, and the mug was heated and cured at 70°C for 1 hour to create a reversible thermochromic layer, thereby obtaining a reversible thermochromic mug. At room temperature (25°C), the reversible thermochromic layer of the mug develops a highly fluorescent pink color, making the heart pattern visible. However, when 58°C hot water is poured into the mug, the reversible thermochromic layer disappears and becomes colorless. When the water is removed from this state, or when the water temperature drops below 43°C, the reversible thermochromic layer reappears, and a highly fluorescent pink heart pattern becomes visible again. This change in appearance could be repeated by changing the temperature.

[0097] Application Example 3: Production of a doll toy with hair using reversible thermochromic composite fibers Five parts of the reversible thermochromic microcapsule pigment prepared in Example 8, one part of a dispersant, and 94 parts of a polypropylene-ethylene copolymer with a melting point of 135°C were melt-mixed in an extruder at 200°C to prepare a pellet-shaped reversible thermochromic molding resin composition. The reversible thermochromic molding resin composition was supplied to an extruder for core molding, and 6-12 copolymer nylon natural pellets with a melting point of 145°C were supplied to an extruder for sheath molding. Using a composite fiber spinning device, the fibers were spun out at 200°C from an 18-hole discharge port so that the volume ratio of the core to the sheath was 6:4, to prepare a reversible thermochromic composite fiber consisting of 18 single filaments with an outer diameter of 90 μm. Furthermore, the reversible thermochromic composite fiber was implanted into the head of a doll using a hair implantation machine to produce a doll toy with hair made of the reversible thermochromic composite fiber. The hair of the doll toy turned a highly fluorescent pink at temperatures below 28°C and white at temperatures above 35°C. This color change was reversible. Furthermore, this reversible color change was highly sensitive, and the hair in question changed color with high sensitivity.

[0098] Application Example 4 Preparation of a Reversible Thermochromic Display Body A reversible thermochromic display body was obtained by printing a reversible color change layer on the surface of a white polyester film (thickness 25 μm) as a support, using an ink in which the reversible thermochromic microcapsule pigment prepared in Example 9 was dispersed in a vehicle containing a binder resin. The surface was then laminated with a transparent polyester film with a thickness of 16 μm to obtain a reversible thermochromic display body. The display body was cooled to below -18°C, and after the reversible color change layer was completely colored to a highly fluorescent pink, white cutout letters were formed by printing using a thermal transfer printer. The white cutout letters were visible as long as the display body was maintained in the temperature range of -18°C to 64°C. Furthermore, when the display body was cooled again to below -18°C and the reversible color change layer was completely colored to a highly fluorescent pink, the white cutout letters became invisible, and the display body could be reused many times by forming white cutout letters again using a thermal transfer printer.

[0099] Application Example 5 Preparation of a Ballpoint Pen A reversible thermochromic writing instrument ink composition was prepared consisting of 20 parts of the reversible thermochromic microcapsule pigment prepared in Example 11 (pre-cooled to below -18°C to develop a highly fluorescent pink color), 0.3 parts of xanthan gum, 10 parts of urea, 10 parts of glycerin, 0.5 parts of a nonionic penetrating agent, 0.1 part of a modified silicone-based defoamer, 0.2 parts of a preservative, and 58.9 parts of water. The reversible thermochromic ink composition was suction-filled into a polypropylene pipe and connected to a ballpoint pen tip holding a 0.5 mm stainless steel ball at its tip via a resin holder. Next, a viscoelastic ink backflow prevention body (liquid stopper) mainly composed of polybutene was filled into the rear end of the polypropylene pipe, a tail plug was fitted to the rear of the pipe, the front barrel and rear barrel were assembled, and after attaching the cap, degassing was performed by centrifugation to obtain a ballpoint pen. Furthermore, a SEBS rubber friction element is attached to the rear of the rear axle cylinder. Using the ballpoint pen, writing was done on paper to form highly fluorescent pink letters (handwriting). The handwriting exhibited a highly fluorescent pink color at room temperature (25°C), and when the letters were rubbed with the friction element, the letters disappeared and became colorless. This state could be maintained as long as the temperature was not cooled to below -18°C. Furthermore, when the paper was placed in a freezer and cooled to below -18°C, the letters again showed a discoloration behavior, becoming highly fluorescent pink, and this discoloration behavior could be repeatedly reproduced.

[0100] Application Example 6 Preparation of a Marking Pen A reversible thermochromic writing instrument ink composition was obtained by mixing 25.0 parts of the reversible thermochromic microcapsule pigment prepared in Example 11 (pre-cooled to below -18°C to develop a highly fluorescent pink color), 0.5 parts of a comb-type polymer dispersant [manufactured by Nippon Lubrizol Co., Ltd., trade name: Solspers 43000], 1.0 part of an organic nitrogen sulfur compound [manufactured by Hokko Chemical Industry Co., Ltd., trade name: Hokuside R-150, a mixture of 2-methyl-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one], 0.5 parts of polyvinyl alcohol, 35.0 parts of glycerin, 0.02 parts of an antifoaming agent, and 37.98 parts of water. An ink composition was impregnated into an ink-absorbing body made of polyester sliver coated with a synthetic resin film, and housed in a barrel made of polypropylene resin. A resin-processed pen body (chisel type) made of polyester fiber was assembled to the tip of the barrel via a holder, and a cap was attached to obtain a marking pen. SEBS resin was attached to the rear end of the barrel as a friction member. Writing was done on paper using the marking pen to form highly fluorescent pink characters (handwriting). The characters exhibited a highly fluorescent pink color at room temperature (25°C), and when the characters were rubbed with a friction material, the characters disappeared and became colorless. This state could be maintained as long as the temperature was not cooled to below -18°C. When the paper was placed in a freezer and cooled to below -18°C, the characters again showed a discoloration behavior of becoming highly fluorescent pink, and this discoloration behavior could be repeatedly reproduced.

[0101] t １ Complete color development temperature t of heat-decolorizing reversible thermochromic composition ２ Temperature at which color development begins for a heat-decolorizing, reversible thermochromic composition t ３ Decolorization start temperature t of heat-decolorizing type reversible thermochromic composition ４ Complete decolorization temperature T of a heat-decolorizing type reversible thermochromic composition １ The complete decolorization temperature T of a heat-activated, reversible thermochromic composition. ２ Discoloration onset temperature T for a heat-activated, reversible thermochromic composition ３ The color development start temperature T of a heat-activated, reversible thermochromic composition. ４Complete color development temperature ΔH and hysteresis width of a heat-activated, reversible thermochromic composition.

Claims

1. (A) A fluoran derivative represented by the following general formula (1) as an electron-donating color-forming organic compound, (B) an electron-accepting compound, and (C) a reaction medium that reversibly causes an electron transfer reaction between the components (A) and (B) in a specific temperature range, at least comprising a reversible thermochromic composition. [In general formula (1), R １１ and R １３ each independently represent an alkyl group which may have a substituent, R １２ and R １４ each independently represent a group represented by the following general formula (2), R １５ represents a halogen atom, an alkyl group which may have a substituent or an alkoxy group which may have a substituent, a represents an integer from 0 to 4, and when a represents an integer from 2 to 4, a plurality of R １５ may be the same or different. In general formula (2), R ２１ and R ２２ each independently represent an alkyl group which may have a substituent, b represents an integer from 1 to 4, and when b represents an integer from 2 to 4, a plurality of R ２２ may be the same or different, and * indicates the bonding site with the nitrogen atom in general formula (1).] 2. R in general formula (1) １１ and R １３ The compound according to claim 1, wherein each of the three groups is independently an alkyl group having 6 to 12 carbon atoms, which may have substituents, or a group represented by the following general formula (3). [In general formula (3), R ３１ This includes a halogen atom, an optionally substituted alkyl group, an optionally substituted alkoxy group, and -C(O)-R ３２ , -C(O)-OR ３３ , -O-C(O)-R ３４ , -SO ２ -R ３５ , represents a nitro group or a cyano group, R ３２ , R ３３ and R ３４ R independently represents a hydrogen atom, an optionally substituted alkyl group, or an optionally substituted aryl group. ３５ R represents a hydroxyl group, an optionally substituted alkyl group, or an optionally substituted aryl group; L represents an optionally substituted alkylene group; c represents an integer from 0 to 5; and if c represents an integer from 2 to 5, there are multiple R ３１ These may be the same or different, and * indicates the bonding site with the nitrogen atom in general formula (1).

3. In general formula (1), R １１ and R １３ These are, independently of each other, an alkyl group having 6 to 12 carbon atoms, or a group represented by the general formula (3), where R ３１ This includes halogen atoms, C1-C6 alkyl groups, C1-C6 alkoxy groups, and -C(O)-R ３２ , -C(O)-OR ３３ , -O-C(O)-R ３４ , -SO ２ -R ３５ , represents a nitro group or a cyano group, R ３２ , R ３３ and R ３４ Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms which may have substituents, or an aryl group having 6 to 12 carbon atoms which may have substituents, R ３５ R represents a hydroxyl group, an optionally substituted C1-C6 alkyl group, or an optionally substituted C6-C12 aryl group; L represents a C1-C4 alkylene group; c represents an integer from 0 to 2; if c is 2, then two R ３１ The reversible thermochromic composition according to claim 1 or 2, wherein the elements may be the same or different.

4. In general formula (2), R ２１ and R ２２ Each of the following independently represents an alkyl group having 1 to 6 carbon atoms, and b represents an integer from 1 to 3. If b represents an integer from 2 to 3, then multiple R ２２ The reversible thermochromic composition according to claim 1 or 2, wherein the elements may be the same or different.

5. In general formula (1), R １１ and R １３ These are groups that are independently represented by the general formula (3), and R １５ R is a halogen atom, a C1-C4 alkyl group, or a C1-C4 alkoxy group, where a is an integer from 0 to 1, and in general formula (2), R ２１ and R ２２ R represents an alkyl group with 1 to 4 carbon atoms, and b represents an integer from 1 to 2. When b represents 2, two R ２２ They may be the same or different, and in general formula (3), R ３１ represents a halogen atom, a cyano group, or an alkyl group having 1 to 4 carbon atoms; L represents an alkylene group having 1 to 2 carbon atoms; c represents an integer from 1 to 2; if c represents 2, then two R ３１ The reversible thermochromic composition according to claim 1 or 2, wherein the elements may be the same or different.

6. The reversible thermochromic composition according to claim 1 or 2, comprising 0.1 to 100 parts by mass of component (b) and 1 to 800 parts by mass of component (c) per 1 part by mass of component (a).

7. A reversible thermochromic microcapsule pigment comprising the reversible thermochromic composition described in claim 1 or 2.

8. A reversible thermochromic liquid composition comprising the reversible thermochromic microcapsule pigment described in claim 7 and a vehicle.

9. The reversible thermochromic liquid composition according to claim 8, selected from the group consisting of printing inks, writing instrument inks, applicator inks, stamp inks, inkjet inks, paints, UV-curing inks, paints, cosmetics, and textile colorants.

10. A reversible thermochromic molding resin composition comprising the reversible thermochromic microcapsule pigment described in claim 7 and a molding resin.

11. A reversible thermochromic molded article obtained by molding the reversible thermochromic moldable resin composition described in claim 10.

12. A reversible thermochromic laminate comprising a support and a reversible thermochromic layer comprising the reversible thermochromic microcapsule pigment described in claim 7.

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