Reversible thermochromic composition and reversible thermochromic microcapsule pigment enclosing the same

Abstract

To provide: a reversible thermochromic composition which reversibly performs color change from pink to colorless and which has excellent contrast between a color development state and a colorless state by applying a combination of a specific diazarhodamine lactone derivative as an electron-donating color-developing organic compound and a compound with a specific structure as an electron-accepting compound; and a reversible thermochromic microcapsule pigment enclosing the same.SOLUTION: Provided are: a reversible thermochromic composition comprising a combination of (a) a compound having a specific structure as an electron-donating color developable organic compound, and (b) compounds having specific structures as electron-accepting compounds, and (c) a reaction medium which reversibly causes an electron-donating or accepting reaction caused by the component (a) and the component (b) in a specific temperature range; and a reversible thermochromic microcapsule pigment enclosing the composition.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a reversible thermochromic composition and a reversible thermochromic microcapsule pigment encapsulating the same. More specifically, the present invention relates to a reversible thermochromic composition that exhibits pink color when colored and changes to colorless when decolorized, and a reversible thermochromic microcapsule pigment encapsulating the same. [Background technology]

[0002] Conventionally, a reversible thermochromic composition has been disclosed that reversibly changes color from red or pink to colorless, and that contains as essential components a specific diazarhodamine lactone derivative as an electron-donating color-forming organic compound, an electron-accepting compound, and a reaction medium that reversibly induces an electron donor / acceptor reaction between the electron-donating color-forming organic compound and the electron-accepting compound in a specific temperature range (see, for example, Patent Document 1). A reversible thermochromic composition is required to have a high density in the colored state and a low density in the decolorized state, that is, to have excellent contrast. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-105428 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention has been made based on the background technology as described above, and aims to provide a reversible thermochromic composition that reversibly changes color from pink to colorless and has a large difference in density between the colored state and the decolorized state (excellent contrast between the colored state and the decolorized state), and a reversible thermochromic microcapsule pigment encapsulating the same. [Means for solving the problem]

[0005] The present invention relates to (a) a compound represented by the following formula (A) as an electron-donating organic color former; (ii) a combination of a compound represented by the following formula (Ba) and a compound represented by the following formula (Bb) as an electron accepting compound; (c) a reaction medium that causes a reversible electron donor-acceptor reaction between the components (a) and (b) in a specific temperature range; and The present invention relates to a reversible thermochromic composition comprising: [ka] (In the formula, R 11 and R 12 each independently represents a hydrogen atom; an alkyl group having 1 to 8 carbon atoms which may be substituted by a hydroxy group; an alkoxyalkyl group having 2 to 12 carbon atoms; a carboalkoxyalkyl group having 4 to 11 carbon atoms; a phenylalkyl group having 7 to 12 carbon atoms; or a phenyl group which may be substituted by a halogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, However, R 11 and R 12 and may together form a ring, R 13 and R 14 each independently represents a hydrogen atom; an alkyl group having 1 to 8 carbon atoms which may be substituted by a hydroxy group; a cycloalkyl group having 5 to 7 carbon atoms; an alkoxyalkyl group having 2 to 12 carbon atoms; a carboalkoxyalkyl group having 4 to 11 carbon atoms; or a phenylalkyl group having 7 to 12 carbon atoms, However, R 13 and R 14 and may together form a ring, R 15 represents an alkyl group having 1 to 3 carbon atoms; an alkoxy group having 1 to 4 carbon atoms; or a phenyl group which may be substituted with a halogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, R 16 and R 17 each independently represents a halogen atom; a hydroxyl group or an alkyl group having 1 to 3 carbon atoms which may be substituted by a halogen atom, n16 is an integer from 0 to 3, n17 is an integer from 0 to 4. [ka] (In the formula, R a1 and R a2 each independently represents a hydrogen atom; an alkyl group having 1 to 17 carbon atoms which may be substituted by a fluorine atom (wherein a methylene group (-CH-) in the alkyl group may be replaced by an oxy group (-O-) or a carbonyl group (-CO-)); or an aryl group having 6 to 10 carbon atoms, R a3 and R a4 each independently represents an alkyl group having 1 to 4 carbon atoms which may be substituted by a fluorine atom or a hydroxy group; an alkenyl group having 2 to 4 carbon atoms; or a halogen atom, Each of na3 and na4 independently represents an integer of 0 to 2. [ka] (In the formula, R b1 is a hydroxy group or an alkyl group having 1 to 10 carbon atoms (wherein R b1 at least one of which is a hydroxy group; R b2 is an alkyl group having 1 to 10 carbon atoms, nb1 is an integer from 1 to 4, nb2 is an integer from 0 to 3.) In addition, the R a1 and R a2 At least one of R is an alkyl group having 1 to 9 carbon atoms or a phenyl group. b1is a hydroxy group, nb1 is 1, the mass ratio of the compound represented by formula (Ba) to the compound represented by formula (Bb) is 2:8 to 8:2, the component (C) is an ester compound showing a ΔT value (melting point-cloud point) of 3°C or less, and the content of the component (C) is in the range of 0.1 to 100 parts by mass and the content of the component (C) is in the range of 1 to 800 parts by mass per part by mass of the component (A). Furthermore, the present invention also requires a reversible thermochromic microcapsule pigment containing the reversible thermochromic composition described above. Furthermore, the present invention also provides a reversible thermochromic liquid composition comprising the above-mentioned reversible thermochromic microcapsule pigment and a vehicle. A further feature of the present invention is a solid writing material or a solid cosmetic material comprising the reversible thermochromic microencapsulated pigment and an excipient. A further feature is a reversible thermochromic molding resin composition comprising the above-mentioned reversible thermochromic microencapsulated pigment and a molding resin. A further feature of the present invention is a reversibly thermochromic laminate comprising a support and a reversibly thermochromic layer containing the reversibly thermochromic microencapsulated pigment. Effect of the Invention

[0006] The present invention provides a reversible thermochromic composition that employs a combination of a specific diazarhodamine lactone derivative as an electron-donating organic color-forming compound and a compound having a specific structure as an electron-accepting compound, and a reversible thermochromic microcapsule pigment encapsulating the same, which reversibly changes color from pink to colorless and has an excellent contrast between the colored state and the decolorized state, and a reversible thermochromic microcapsule pigment encapsulating the same. [Brief description of the drawings]

[0007] [Figure 1] 1 is a graph illustrating hysteresis characteristics in a color density-temperature curve of a heat-discolorable, reversible thermochromic composition. [Diagram 2]1 is a graph illustrating hysteresis characteristics in a color density-temperature curve of a heat-discolorable, reversible thermochromic composition having color memory properties. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The reversible thermochromic composition according to the present invention includes a reversible thermochromic composition of the heat-discolorable type (discolored by heating and colored by cooling) that contains at least three essential components: (i) an electron-donating color-forming organic compound, (ii) an electron-accepting compound, and (iii) a reaction medium that determines the temperature at which the color-forming reaction of components (i) and (ii) occurs. The above-mentioned reversible thermochromic composition changes color just before and just after a certain temperature (discoloration point), exhibiting a discolored state in the temperature range above the high-temperature discoloration point and a colored state in the temperature range below the low-temperature discoloration point; of these two states, only one specific state exists in the room temperature range, and the other state is maintained as long as the heat or cold required to manifest that state is applied, but returns to the state it exhibits in the room temperature range when the application of heat or cold is removed; the composition has a relatively small hysteresis width (ΔH) (see Figure 1).

[0009] In addition, it is also possible to use a reversible thermochromic composition that exhibits a large hysteresis width, in other words, the shape of the curve plotting the change in color density due to temperature change follows a path that is significantly different when the temperature is increased from a lower temperature side than the color change temperature range from that when the temperature is decreased from a higher temperature side than the color change temperature range, and that has color memory in a specific temperature range [the temperature range between the color development onset temperature t2 and the color loss onset temperature t3 (temperature range that essentially maintains two phases)], with a colored state in a temperature range below the complete color development temperature t1, or a colorless state in a high temperature range above the complete color loss temperature t4 (see Figure 2).

[0010] The following describes each of the components (a), (b), and (c) in detail.

[0011] Component (A), that is, the electron-donating organic color-forming compound, is the component that determines the color, and is a compound that develops color by donating electrons to component (B), which is a color developer.

[0012] Component (a) is a compound represented by formula (A). [ka] During the ceremony, R 11 and R 12 each independently represents a hydrogen atom; an alkyl group having 1 to 8 carbon atoms which may be substituted by a hydroxy group; an alkoxyalkyl group having 2 to 12 carbon atoms; a carboalkoxyalkyl group having 4 to 11 carbon atoms; a phenylalkyl group having 7 to 12 carbon atoms; or a phenyl group which may be substituted by a halogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, Preferably, each independently is an alkyl group having 1 to 8 carbon atoms, More preferably, it is an alkyl group having 1 to 8 carbon atoms, and R 11 and R 12 are identical to More preferably, it is an alkyl group having 3 to 6 carbon atoms, and R 11 and R 12 are identical. R 11 and R 12 may form a ring, but it is also preferred that they do not form a ring. R 13 and R 14 each independently represents a hydrogen atom; an alkyl group having 1 to 8 carbon atoms which may be substituted by a hydroxy group; a cycloalkyl group having 5 to 7 carbon atoms; an alkoxyalkyl group having 2 to 12 carbon atoms; a carboalkoxyalkyl group having 4 to 11 carbon atoms; or a phenylalkyl group having 7 to 12 carbon atoms, Preferably, each independently is an alkyl group having 1 to 8 carbon atoms, More preferably, it is an alkyl group having 1 to 8 carbon atoms, and R 13 and R 14 are identical to More preferably, it is an alkyl group having 3 to 6 carbon atoms, and R 13 and R 14 are identical. R 13 and R 14may form a ring, but it is also preferred that they do not form a ring. R 15 represents an alkyl group having 1 to 3 carbon atoms; an alkoxy group having 1 to 4 carbon atoms; or a phenyl group which may be substituted with a halogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, Preferably, it is an alkyl group having 1 to 4 carbon atoms. A methyl group is more preferred. R 16 and R 17 each independently represents a halogen atom; or an alkyl group having 1 to 3 carbon atoms which may be substituted by a hydroxyl group or a halogen atom. n16 is an integer of 0 to 3, preferably 0 or 1, and more preferably 0. n17 is an integer of 0 to 4, preferably 0 or 1, and more preferably 0.

[0013] R 11 , R 12 , R 13 , and R 14 Regarding the above, the alkoxyalkyl group having 2 to 12 carbon atoms is -(CH2) m -O-(CH2) n H (wherein m and n each independently represent an integer of 1 to 11, provided that the sum of m and n is 2 to 12, (CH2) m and (CH2) n The group represented by may be linear or branched. ) is a group represented by, for example, a methoxymethyl group, a tert-butoxymethyl group, a tert-butoxyhexyl group, a 1-ethoxyethyl group, a 1-methyl-1-methoxyethyl group, etc.

[0014] R 11 , R 12 , R 13 , and R 14 Regarding the above, the carboalkoxyalkyl group having 4 to 11 carbon atoms is -(CH2) m -COO-(CH2) nH (wherein m and n each independently represent an integer of 1 to 9, provided that the sum of m and n is 3 to 10; (CH2) m and (CH2) n may be linear or branched.) and examples thereof include a carboethoxymethyl group, a carbomethoxyethyl group, a carboethoxyethyl group, a carbomethoxypropyl group, a carbomethoxyoctyl group, a carbopropoxymethyl group, a carbopropoxyethyl group, a carbopropoxypropyl group, a carbooctoxymethyl group, and a carbooctoxyethyl group.

[0015] R 11 , R 12 , R 13 , and R 14 Regarding the above, the phenylalkyl group having 7 to 12 carbon atoms is -(CH2) n -R (wherein n is an integer of 1 to 6, R is a phenyl group, (CH2) n The group represented by may be linear or branched. ) is a group represented by, for example, a benzyl group, a phenethyl group, a phenylpropyl group, a phenylbutyl group, etc.

[0016] R 11 and R 12 , or R 13 and R 14 When forming a ring, in addition to a 5- to 7-membered saturated heterocyclic ring, an oxygen atom, a sulfur atom, -N(-R 18 )-(R 18 represents a hydrogen atom, a methyl group, or an ethyl group. ) may be a six-membered heterocycle containing a group represented by the formula: When n16 or n17 is an integer equal to or greater than 2, R 16 or R 17 may each be a different group.

[0017] Examples of the compound represented by formula (I) include 2-(Dimethylamino)-8-(dimethylamino)-4-methyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(diethylamino)-8-(diethylamino)-4-methyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(di-n-propylamino)-8-(di-n-propylamino)-4-methyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(di-n-butylamino)-8-(di-n-butylamino)-4-methyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(di-n-butylamino)-8-(dimethylamino)-4-methyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(di-n-butylamino)-8-(diethylamino)-4-methyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(di-n-butylamino)-8-(N-ethyl-Ni-butylamino)-4-methyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(di-n-butylamino)-8-(N-ethyl-Ni-amylamino)-4-methyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(di-n-butylamino)-8-(N-ethyl-Nn-hexylamino)-4-methyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(di-n-butylamino)-8-(di-n-pentylamino)-4-methyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(di-n-butylamino)-8-(n-octylamino)-4-methyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(Dimethylamino)-8-(diethylamino)-4-methyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(diethylamino)-8-(dimethylamino)-4-methyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(morpholino)-8-(diethylamino)-4-methyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(piperidino)-8-(diethylamino)-4-methyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(N-methylpiperazino)-8-(diethylamino)-4-methyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(pyrrolidino)-8-(diethylamino)-4-methyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(diethylamino)-8-(diethylamino)-4-methyl-4′,5′,6′,7′-tetrachloro-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(diethylamino)-8-(diethylamino)-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(di-n-butylamino)-8-(di-n-butylamino)-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(N-ethyl-Ni-amylamino)-8-(N-ethyl-Ni-amylamino)-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(di-n-butylamino)-8-(diethylamino)-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(di-n-butylamino)-8-(N-ethyl-Ni-amylamino)-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(piperidino)-8-(ethylamino)-4-methyl-7-methyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(di-n-butylamino)-8-(diethylamino)-4-methyl-7-methyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(di-n-butylamino)-8-(diethylamino)-4-methyl-7-ethyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(di-n-butylamino)-8-(diethylamino)-4-phenyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(di-n-butylamino)-8-(di-n-butylamino)-4-phenyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(di-n-butylamino)-8-(N-ethyl-Ni-amylamino)-4-phenyl-spiro[5H-(1)benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(piperidino)-8-(diethylamino)-4-phenyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(N-methyl-N-cyclohexylamino)-8-(diethylamino)-4-phenyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(Dimethylamino)-8-(diethylamino)-4-phenyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(i-amylamino)-8-(diethylamino)-4-phenyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(pyrrolidino)-8-(diethylamino)-4-phenyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(N-methylpiperazino)-8-(diethylamino)-4-phenyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(morpholino)-8-(diethylamino)-4-phenyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(N-methyl-N-benzylamino)-8-(diethylamino)-4-phenyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-[di-(2-methoxyethyl)amino]-8-(diethylamino)-4-phenyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(di-n-butylamino)-8-(diethylamino)-4-(4-methoxyphenyl)-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(di-n-butylamino)-8-(diethylamino)-4-(4-chlorophenyl)-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(di-n-butylamino)-8-(diethylamino)-4-(4-methylphenyl)-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-[di-(2-ethoxyethyl)amino]-8-(dimethylamino)-4-phenyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(diethylamino)-8-[(2-methylphenyl)amino]-4-phenyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(2,6-dimethylmorpholino)-8-(diethiamino)-4-phenyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(dicyclohexylamino)-8-(dimethylamino)-4-phenyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-(Dibutylamino)-8-[(4-chlorophenyl)amino]-4-phenyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one Examples include:

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

[0019] The compound represented by the formula (Ba) is as follows: [ka] During the ceremony, R a1 and R a2 are each independently a hydrogen atom; an alkyl group having 1 to 17 carbon atoms which may be substituted by a fluorine atom (wherein a methylene group (-CH-) in the alkyl group may be replaced by an oxy group (-O-) or a carbonyl group (-CO-)); or an aryl group having 6 to 10 carbon atoms, Preferably, each of them is independently a hydrogen atom; an alkyl group having 1 to 11 carbon atoms which may be substituted by a fluorine atom; or a phenyl group. More preferably, R a1 and R a2 at least one of the groups is an alkyl group having 1 to 9 carbon atoms or a phenyl group, More preferably, R a1 and R a2 One of these is an alkyl group having 1 to 9 carbon atoms or a phenyl group, and the other is a hydrogen atom or a methyl group. In the present invention, the aryl group includes an alkyl-substituted aryl group (for example, a tolyl group). R a1 and R a2 may form a ring, but it is also preferred that they do not form a ring. R a3 and R a4 each independently represents an alkyl group having 1 to 4 carbon atoms which may be substituted by a fluorine atom or a hydroxy group; an alkenyl group having 2 to 4 carbon atoms; or a halogen atom, Preferably, it is an alkyl group having 1 to 4 carbon atoms or a halogen atom. More preferably, it is a methyl group or a fluorine atom. na3 and na4 each independently represent an integer of 0 to 2, preferably 0 or 1, and more preferably 0. In a more preferred embodiment, each hydroxy group is present at the 4-position (para-position) of the benzene ring.

[0020] Examples of the compound represented by formula (Ba) include 1,1-bis(4-hydroxyphenyl) n-hexane, 1,1-bis(4-hydroxyphenyl) n-octane, 1,1-bis(4-hydroxyphenyl) n-decane, 1,1-bis(4-hydroxyphenyl)-2-methylpropane, 1,1-bis(4-hydroxyphenyl)-2-ethylbutane, 1,1-bis(4-hydroxyphenyl)-2-ethylhexane, 1-phenyl-1,1-bis(4-hydroxyphenyl)methane, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxyphenyl) n-heptane, 2,2-bis(4-hydroxyphenyl) n-dodecane, 1-phenyl-1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)-4-methylhexane, 2,2-bis(4-hydroxyphenyl)hexafluoropropane, 2,2-bis(4-hydroxy-3-methylphenyl)butane, 2,2-bis(4-hydroxy-3-isopropylphenyl)propane, 2,2-bis(3-fluoro-4-hydroxyphenyl)propane, 9,9-Bis(4-hydroxy-3-methylphenyl)fluorene Examples include:

[0021] The compound represented by formula (Bb) is as follows: [ka] During the ceremony, R b1 is a hydroxyl group or an alkyl group having 1 to 10 carbon atoms (wherein R b1 at least one of which is a hydroxy group; Preferably, it is a hydroxy group or an alkyl group having 1 to 4 carbon atoms. A hydroxy group is more preferred. R b2 is an alkyl group having 1 to 10 carbon atoms, An alkyl group having 1 to 4 carbon atoms is preferred. nb1 is an integer of 1 to 4, preferably 1 or 2, and more preferably 1. nb2 is an integer of 0 to 3, preferably 0 or 1, and more preferably 0.

[0022] Examples of the compound represented by formula (Bb) include 4-(1′,3′,4′,9′a-tetrahydro-6′-hydroxy-spiro[cyclohexane-1,9′-[9H]-xanthene]-4′a(2′H)-yl)-1,3-benzenediol, 4-(1′,3′,4′,9′a-tetrahydro-6′-hydroxy-spiro[cyclohexane-1,9′-[9H]-xanthene]-4′a(2′H)-yl)-1,2-benzenediol, 4-(1′,3′,4′,9′a-tetrahydro-6′-hydroxy-7′-methyl-spiro[cyclohexane-1,9′-[9H]-xanthene]-4′a(2′H)-yl)-6-methyl-1,3-benzenediol, 4-(1′,3′,4′,9′a-tetrahydro-6′-hydroxy-7′-tert-butyl-spiro[cyclohexane-1,9′-[9H]-xanthene]-4′a(2′H)-yl)-6-tert-butyl-1,3-benzenediol Examples include:

[0023] By combining a compound represented by formula (Ba) and a compound represented by formula (Bb) as component (b), it is possible to provide a reversible thermochromic composition that exhibits a pink color when colored and has an excellent contrast between the colored state and the decolorized state. (ii) As compared with the case where the compound represented by formula (Ba) or the compound represented by formula (Bb) is used alone as the component, the reversible thermochromic composition can have an excellent contrast between the colored state and the decolored state. Therefore, as the compound represented by formula (Ba), R a1 and R a2 is a compound in which one of R is an alkyl group having 1 to 9 carbon atoms or a phenyl group, the other is a hydrogen atom or a methyl group, and na3 and na4 are each 0. More preferably, R a1 and R a2 is an alkyl group having 3 to 7 carbon atoms or a phenyl group, the other is a hydrogen atom or a methyl group, and na3 and na4 are each 0. In addition, preferred examples of the compound represented by formula (Bb) include compounds in which R b1 is a hydroxy group, and R b2 is an alkyl group having 1 to 4 carbon atoms, nb1 is 1 or 2, and nb2 is 0 or 1. In terms of availability and excellent productivity, R b1 is a hydroxy group, nb1 is 1, and nb2 is 0. That is, as the compound represented by the formula (Ba), R a1 and R a2 one of which is an alkyl group having 3 to 7 carbon atoms or a phenyl group, the other is a hydrogen atom or a methyl group, and na3 and na4 are each 0; and as a compound represented by formula (Bb), R b1 is a hydroxy group, nb1 is 1, and nb2 is 0.

[0024] The mass ratio of the compound represented by formula (Ba) to the compound represented by formula (Bb) in the reversible thermochromic composition of the present invention is not particularly limited, but is preferably in the range of 2:8 to 8:2, more preferably 3:7 to 7:3, and even more preferably 4:6 to 6:4. When the mass ratio is within the above range, it becomes easy to achieve a more excellent contrast between the colored state and the decolored state.

[0025] The reversible thermochromic composition of the present invention, which uses a combination of a compound represented by formula (Ba) and a compound represented by formula (Bb) as component (b), is unlikely to lose its reversible thermochromic function, in which it becomes discolored in a temperature range above the high-temperature discoloration point (complete discoloration temperature) and becomes colored in a temperature range below the low-temperature discoloration point (complete color development temperature), even when subjected to repeated temperature changes, and the concentration in the colored state and the concentration in the discolored state are unlikely to change even when used repeatedly.

[0026] The component (iii) of the reaction medium that reversibly induces an electron donor-recipient reaction between the components (a) and (b) in a specific temperature range will now be described. Examples of the component (c) include alcohols, esters, ketones, ethers, and acid amides. When the reversible thermochromic composition of the present invention is applied to microencapsulation and secondary processing, compounds having 10 or more carbon atoms are preferably used in order to stably retain the compound in the capsule, since low molecular weight compounds will evaporate out of the capsule when subjected to high heat treatment. The component (c) can be used alone or in combination of two or more.

[0027] As the alcohol, aliphatic monohydric saturated alcohols having 10 or more carbon atoms are effective.

[0028] As the esters, esters having 10 or more carbon atoms are effective, and examples thereof include esters obtained from any combination of a monovalent carboxylic acid having an aliphatic and an alicyclic ring or an aromatic ring and a monohydric alcohol having an aliphatic and an alicyclic ring or an aromatic ring, esters obtained from any combination of a polyvalent carboxylic acid having an aliphatic and an alicyclic ring or an aromatic ring and a monohydric alcohol having an aliphatic and an alicyclic ring or an aromatic ring, and esters obtained from any combination of a monovalent carboxylic acid having an aliphatic and an alicyclic ring or an aromatic ring and a polyhydric alcohol having an aliphatic and an alicyclic ring or an aromatic ring.

[0029] Furthermore, in order to change color while exhibiting a large hysteresis characteristic in the color density-temperature curve and to impart color memory depending on temperature change, a carboxylate compound having a ΔT value (melting point-cloud point) of 5°C or more and less than 50°C, as described in JP-B-4-17154, is also effective.

[0030] Also effective are fatty acid ester compounds obtained from an aliphatic monohydric alcohol having an odd number of carbon atoms of 9 or more and an aliphatic carboxylic acid having an even number of carbon atoms, and fatty acid ester compounds having a total of 17 to 23 carbon atoms obtained from n-pentyl alcohol or n-heptyl alcohol and an aliphatic carboxylic acid having an even number of carbon atoms of 10 to 16.

[0031] As the ketones, aliphatic ketones having a total of 10 or more carbon atoms are effective, and examples thereof include aryl alkyl ketones having a total of 12 to 24 carbon atoms.

[0032] As the ethers, aliphatic ethers having a total of 10 or more carbon atoms are effective.

[0033] Examples of the above alcohols, esters, ketones, ethers, and acid amides include the compounds described in JP-A-2020-100710.

[0034] Furthermore, the component (iii) may be a compound represented by the following formula (1). [ka] (In the formula, R1 represents a hydrogen atom or a methyl group, m represents an integer of 0 to 2, and either X1 or X2 is -(CH2) n -OCO-R2 or -(CH2) n -COO-R2, the other represents a hydrogen atom, n represents an integer of 0 to 2, R2 represents an alkyl or alkenyl group having 4 or more carbon atoms, Y1 and Y2 each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a methoxy group, or a halogen atom, and r and p each independently represent an integer of 1 to 3. Of the compounds represented by formula (1), it is preferable that R1 is a hydrogen atom, since a reversible thermochromic composition having a wider hysteresis width can be obtained, and it is even more preferable that R1 is a hydrogen atom and m is 0. Among the compounds represented by formula (1), a compound represented by the following formula (2) is more preferred. [ka] (In the formula, R represents an alkyl group or alkenyl group having 8 or more carbon atoms, preferably an alkyl group having 10 to 24 carbon atoms, and more preferably an alkyl group having 12 to 22 carbon atoms.)

[0035] Furthermore, the component (iii) may be a compound represented by the following formula (3). [ka] (In the formula, R represents an alkyl or alkenyl group having 8 or more carbon atoms, m and n each independently represent an integer of 1 to 3, and X and Y each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom.)

[0036] Furthermore, the component (iii) may be a compound represented by the following formula (4). [ka] (In the formula, X represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a methoxy group, or a halogen atom, m represents an integer of 1 to 3, and n represents an integer of 1 to 20.)

[0037] Furthermore, the component (iii) may be a compound represented by the following formula (5). [ka] (In the formula, R represents an alkyl group or alkenyl group having 1 to 21 carbon atoms, and n represents an integer of 1 to 3.)

[0038] Furthermore, the component (iii) may be a compound represented by the following formula (6). [ka] (In the formula, X represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom, m represents an integer of 1 to 3, and n represents an integer of 1 to 20.)

[0039] Furthermore, the component (iii) may be a compound represented by the following formula (7). [ka] (In the formula, R represents any one of an alkyl group having 4 to 22 carbon atoms, a cycloalkylalkyl group, a cycloalkyl group, and an alkenyl group having 4 to 22 carbon atoms; X represents any one of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and a halogen atom; and n represents 0 or 1.)

[0040] Furthermore, the component (iii) may be a compound represented by the following formula (8). [ka] (In the formula, R represents an alkyl group having 3 to 18 carbon atoms or an aliphatic acyl group having 3 to 18 carbon atoms; X represents any one of a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 or 2 carbon atoms, and a halogen atom; Y represents a hydrogen atom or a methyl group; and Z represents any one of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 or 2 carbon atoms, and a halogen atom.)

[0041] Furthermore, the component (iii) may be a compound represented by the following formula (9). [ka] (In the formula, R represents any one of an alkyl group having 4 to 22 carbon atoms, an alkenyl group having 4 to 22 carbon atoms, a cycloalkylalkyl group, and a cycloalkyl group; X represents any one of a hydrogen atom, an alkyl group, an alkoxy group, and a halogen atom; Y represents any one of a hydrogen atom, an alkyl group, an alkoxy group, and a halogen atom; and n represents 0 or 1.)

[0042] Furthermore, the component (iii) may be a compound represented by the following formula (10). [ka] (In the formula, R represents any one of an alkyl group having 3 to 18 carbon atoms, a cycloalkylalkyl group having 6 to 11 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, and an alkenyl group having 3 to 18 carbon atoms; X represents any one of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, and a halogen atom; and Y represents any one of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a methoxy group, an ethoxy group, and a halogen atom.)

[0043] Furthermore, the component (iii) may be a compound represented by the following formula (11). [ka] (In the formula, R represents a cycloalkyl group having 3 to 8 carbon atoms or a cycloalkylalkyl group having 4 to 9 carbon atoms, and n represents an integer of 1 to 3.)

[0044] Furthermore, the component (iii) may be a compound represented by the following formula (12). [ka] (In the formula, R represents any one of an alkyl group having 3 to 17 carbon atoms, a cycloalkyl group having 3 to 8 carbon atoms, and a cycloalkylalkyl group having 5 to 8 carbon atoms; X represents any one of a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a methoxy group, an ethoxy group, and a halogen atom; and n represents an integer of 1 to 3.)

[0045] Examples of the compounds represented by formulas (2) to (12) include the compounds described in JP-A-2020-100710.

[0046] As the component (c), an ester compound showing a ΔT value (melting point-cloud point) of 3°C or less (preferably 2.5°C or less) is also effective. The reversible thermochromic composition according to the present invention using such an ester compound as the component (c) has a property of extremely small hysteresis width (ΔH) and a property of a sharp reversible change from a colored state to a discolored state. That is, it can be a reversible thermochromic composition that changes color with high sensitivity. Here, the smaller the difference (t2-t1) between the color development start temperature t2 and the complete color development temperature t1 of the reversible thermochromic composition and the smaller the difference (t4-t3) between the complete discoloration temperature t4 and the discoloration start temperature t3 of the reversible thermochromic composition, the sharper the reversible change from a colored state to a discolored state, and the more sensitive the reversible thermochromic composition becomes to change color. The highly sensitive color change behavior of the reversible thermochromic composition is effective when the compound represented by formula (Bb) is blended in an amount of 0.5 parts by mass or more per part by mass of the compound represented by formula (Ba) in the reversible thermochromic composition, and is most effective when the mass ratio of the compound represented by formula (Ba) to the compound represented by formula (Bb) is 2:8 to 6:4. t2-t1 and t4-t3 are preferably 5°C or less, more preferably 4°C or less, even more preferably 3°C or less, and particularly preferably 2°C or less.

[0047] Examples of ester compounds having a ΔT value of 3° C. or less include esters of saturated fatty acids and branched aliphatic alcohols, esters of unsaturated fatty acids or branched or substituted saturated fatty acids and branched aliphatic alcohols or aliphatic alcohols having 16 or more carbon atoms, and ester compounds selected from cetyl butyrate, stearyl butyrate, and behenyl butyrate. For example, 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, 3,5,5-trimethylhexyl behenate, 2-methylbutyl caproate, 2-methylbutyl caprylate, 2-methylbutyl caprate, 1-ethylpropyl palmitate, 1-ethylpropyl stearate, 1-ethylpropyl behenate 1-ethylhexyl laurate, 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-methylheptyl caproate -Ethylpentyl, 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 3,7-dimethyloctyl, stearyl oleate, behenyl oleate, stearyl linoleate, behenyl linoleate, 3,7-dimethyloctyl erucate, stearyl erucate, isostearyl erucate, cetyl isostearate, stearyl isostearate, 2-methylpentyl 12-hydroxystearate, 2-ethylhexyl 18-bromostearate, isostearyl 2-ketomyristate, 2-ethylhexyl 2-fluoromyristate, cetyl butyrate, stearyl butyrate, and behenyl butyrate.

[0048] The reversible thermochromic composition according to the present invention is a compatible body containing the above-mentioned components (A), (B), and (C) as essential components, and the ratio of each component depends on the concentration, color change temperature, color change form, and type of each component, but the component ratio that generally obtains the desired characteristics is in the range of 0.1 to 100, preferably 0.1 to 50, more preferably 0.5 to 20, and 1 to 800, preferably 5 to 200, more preferably 5 to 100, and even more preferably 10 to 100 for component (A) 1 (all the above ratios 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 is easy to show high concentration in the colored state and easy to reduce residual color in the decolored state, that is, a reversible thermochromic composition that has a better contrast between the colored state and the decolored state.

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

[0050] By blending a non-color-changing colorant such as a general dye or pigment with the reversible thermochromic composition of the present invention, it is possible to make it exhibit a color change behavior from color (1) to color (2).

[0051] The reversible thermochromic composition of the present invention is effective when used as is, but it can also be encapsulated in microcapsules to form a reversible thermochromic microcapsule pigment (hereinafter sometimes referred to as a "microcapsule pigment"), or dispersed in a thermoplastic resin or a thermosetting resin to form reversible thermochromic resin particles (hereinafter sometimes referred to as a "resin particle"). The reversible thermochromic composition is preferably encapsulated in a microcapsule to form a reversible thermochromic microcapsule pigment, because the encapsulation in a microcapsule makes it possible to form a chemically or physically stable pigment, and furthermore, the reversible thermochromic composition can be maintained in the same composition under various conditions of use, and can exhibit the same action and effect. Microencapsulation can be appropriately selected according to the application, from among the conventionally known isocyanate-based interfacial polymerization method, melamine-formaldehyde-based in situ polymerization method, liquid curing coating method, phase separation method from an aqueous solution, phase separation method from an organic solvent, melt dispersion cooling method, air suspension coating method, spray drying method, etc. Furthermore, a secondary resin film can be further provided on the surface of the microcapsule according to the purpose to impart durability or modify the surface properties for practical use. The reversible thermochromic microcapsule pigment preferably has a mass ratio of inclusions to wall film of 7:1 to 1:1, and by having the mass ratio of inclusions to wall film within the above range, the decrease in color density and clarity during color development is prevented. More preferably, the mass ratio of inclusions to wall film is 6:1 to 1:1.

[0052] The average particle size of the reversible thermochromic microencapsulated pigment or resin particles is preferably 0.01 to 50 μm, more preferably 0.1 to 30 μm, and even more preferably 0.5 to 20 μm. If the average particle size exceeds 50 μm, the dispersion stability and processing suitability are lacking when blended into ink, paint, or resin. On the other hand, if the average particle size is less than 0.01 μm, it becomes difficult to exhibit high-concentration color development. When the microencapsulated pigment or resin particles are used in ink for writing instruments, the average particle size is preferably 0.01 to 5 μm, more preferably 0.05 to 4 μm, even more preferably 0.1 to 3 μm, and particularly preferably 0.5 to 3 μm. If the average particle size exceeds 5 μm, it becomes difficult to obtain good ink dischargeability when used in a writing instrument. On the other hand, if the average particle size is less than 0.01 μm, it becomes difficult to exhibit high-concentration color development.

[0053] The average particle size was measured by determining the particle area using image analysis particle size distribution measurement software (manufactured by Mountec Corporation, product name: MacView), calculating the projected area equivalent circle diameter (Heywood diameter) from the area of ​​the particle area, and measuring the average particle size of particles equivalent to a sphere of equal volume using this value. If the particle size of all or the majority of the particles exceeds 0.2 μm, it is also possible to measure the average particle size of particles equivalent to an equal volume sphere by the Coulter method using a particle size distribution analyzer (product name: Multisizer 4e, manufactured by Beckman Coulter, Inc.). Furthermore, the volumetric particle size and average particle size may be measured using a calibrated laser diffraction / scattering particle size distribution analyzer (manufactured by HORIBA, Ltd., product name: LA-300) based on values ​​measured using the above software or a measuring device using the Coulter method.

[0054] The reversible thermochromic colorant, such as the reversible thermochromic composition, the reversible thermochromic microencapsulated pigment, or the reversible thermochromic resin particles, according to the present invention, is dispersed in a vehicle containing at least one of water and an organic solvent and, if necessary, various additives to prepare an ink composition (hereinafter, sometimes referred to as "ink"), It can be used as a liquid composition such as printing ink used in screen printing, offset printing, process printing, gravure printing, coater, pad printing, etc.; paint used in brush coating, spray coating, electrostatic coating, electrocoating, flow coating, roller coating, dip coating, etc.; inkjet ink; ultraviolet-curing ink; ink for writing instruments such as marking pens, ballpoint pens, fountain pens, and brush pens; ink for applicators; ink for stamps; paints; cosmetics; and coloring liquid for textiles.

[0055] The liquid composition may contain various additives. Examples of additives include resins, crosslinking agents, curing agents, drying agents, plasticizers, viscosity modifiers, dispersants, UV absorbers, antioxidants, light stabilizers, anti-settling agents, smoothing agents, gelling agents, defoamers, matting agents, penetrating agents, pH adjusters, foaming agents, coupling agents, moisturizing agents, antifungal agents, preservatives, and rust inhibitors.

[0056] Examples of vehicles for use in writing instrument inks include oil-based vehicles containing an organic solvent, and aqueous vehicles containing water and, if necessary, an organic solvent. When the vehicle is an aqueous vehicle, the ink for a writing instrument may contain a water-soluble organic solvent that is compatible with water. The water-soluble organic solvent suppresses the evaporation of water from the ink, prevents fluctuations in the specific gravity of the vehicle, and stably disperses the reversible thermochromic colorant in the ink.

[0057] Examples of organic solvents include ethanol, propanol, butanol, glycerin, sorbitol, triethanolamine, diethanolamine, monoethanolamine, ethylene glycol, diethylene glycol, thiodiethylene glycol, polyethylene glycol, propylene glycol, butylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, sulfolane, 2-pyrrolidone, and N-methyl-2-pyrrolidone.

[0058] When the writing instrument ink contains a water-soluble organic solvent, the content of the water-soluble organic solvent relative to the total mass of the ink composition is not particularly limited, but is preferably in the range of 1 to 40 mass%, more preferably 5 to 30 mass%, and even more preferably 10 to 25 mass%.

[0059] A thickener can be blended into the writing ink, which can suppress aggregation and / or sedimentation of the reversible thermochromic colorant and can also suppress bleeding of handwriting, allowing the formation of good handwriting. As the thickener, any conventionally known substance can be used, but it is preferable to use a substance that can impart shear thinning properties to the ink composition (shear thinning agent). Ink containing a shear thinning agent (shear thinning ink) is highly viscous and does not flow easily when left at rest or under low stress, but easily becomes less viscous when external stress is applied. Therefore, when not writing, it is possible to prevent ink leakage, separation or backflow of ink, and when writing, it is easy to improve the stability of ink ejection from the pen tip. In particular, when such an ink composition is used in a writing instrument (ballpoint pen) equipped with a ballpoint tip as the pen tip, the ink composition is stably held in the ballpoint pen because of its high viscosity when left stationary without shear stress. Therefore, when writing, a strong shear stress is applied to the ink composition due to the rotation of the ball, and the ink composition in the vicinity of the ball is more likely to have a lower viscosity, which can improve the ink discharge stability.

[0060] When the writing instrument ink contains a thickener, the content of the thickener relative to the total mass of the ink composition is not particularly limited, but is preferably in the range of 0.1 to 20% by mass.

[0061] Examples of shear thinning agents include water-soluble polysaccharides, polymers having a molecular weight of 100,000 to 150,000 that are primarily composed of alkyl esters of methacrylic acid, crosslinked poly-N-vinyl carboxylic acid amides, benzylidene sorbitol and its derivatives, benzylidene xylitol and its derivatives, alkali-thickening acrylic resins, crosslinked acrylic acid polymers, inorganic fine particles, nonionic surfactants with an HLB value of 8 to 12, and metal or amine salts of dialkyl sulfosuccinic acid. The shear thinning agents may be used alone or in combination of two or more.

[0062] Examples of water-soluble polysaccharides include xanthan gum, welan gum, zeta sea gum, diutan gum, macrophomopsis gum, succinoglycan, guar gum, locust bean gum and derivatives thereof, hydroxyethyl cellulose, alkyl alginates, glucomannan, agar, carrageenan, and other carbohydrates having gelling ability extracted from seaweed.

[0063] A polymeric flocculant can be blended into the ink for writing instruments. In the ink containing the polymeric flocculant (flocculant ink), the reversible thermochromic colorant forms loose aggregates via the polymeric flocculant, preventing the reversible thermochromic colorants from coming into contact with each other and agglomerating, thereby improving the dispersibility of the reversible thermochromic colorant. When the writing ink contains a polymer flocculant, the reversible thermochromic colorant is preferably a reversible thermochromic microencapsulated pigment.

[0064] Examples of the polymer flocculant include polyvinylpyrrolidone, polyethylene oxide, and water-soluble polysaccharides. Examples of water-soluble polysaccharides include tragacanth gum, guar gum, pullulan, cyclodextrin, water-soluble cellulose derivatives, and the like. Examples of the water-soluble cellulose derivatives include methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxyethyl methyl cellulose, and hydroxypropyl methyl cellulose. Among these polymer flocculants, hydroxyethyl cellulose is preferred because of its excellent dispersibility.

[0065] When the writing ink contains a polymer flocculant, the content of the polymer flocculant relative to the total mass of the ink composition is not particularly limited, but is preferably in the range of 0.1 to 1 mass%, more preferably 0.3 to 0.5 mass%. When the content is within the above range, the reversible thermochromic colorant forms a gentle aggregate, and the effect of improving the dispersibility of the reversible thermochromic colorant can be fully exerted.

[0066] A dispersant can be blended into the ink for writing instruments to improve the dispersibility of the reversible thermochromic colorant. A polymer flocculant and a dispersant can also be used in combination, and when both are used in combination, the dispersibility of the reversible thermochromic colorant can be improved, and the dispersibility of the loose aggregates of the reversible thermochromic colorant formed via the polymer flocculant can be further improved.

[0067] Examples of dispersants include synthetic resins such as polyvinylpyrrolidone, polyvinyl butyral, polyvinyl ether, styrene-maleic acid copolymer, ketone resin, hydroxyethyl cellulose and its derivatives, styrene-acrylic acid copolymer, acrylic polymers, PO·EO adducts, and polyester amine oligomers. Among these dispersants, acrylic polymer dispersants are preferred because they have excellent dispersibility for reversible thermochromic colorants, acrylic polymer dispersants having a carboxy group are more preferred, and acrylic polymer dispersants having a comb structure and a carboxy group in the side chain are even more preferred. A particularly preferred dispersant is an acrylic polymer dispersant having a comb structure and multiple carboxy groups in the side chains, and a specific example is Solsperse 43000 (manufactured by Lubrizol Japan Co., Ltd.).

[0068] When the ink for writing instruments contains a dispersant, the content of the dispersant relative to the total mass of the ink composition is not particularly limited, but is preferably in the range of 0.01 to 2 mass%, more preferably 0.1 to 1.5 mass%. If the content exceeds 2 mass%, the reversible thermochromic colorant is likely to settle or rise when subjected to external vibration, etc. On the other hand, if the content is less than 0.01 mass%, the effect of improving dispersibility is difficult to achieve.

[0069] When the ink for a writing instrument is used in a writing instrument (ballpoint pen) equipped with a ballpoint pen tip, the ink for a writing instrument may be blended with a lubricant. The lubricant improves the lubricity between the ball seat provided inside the tip body and the ball provided at the front end of the tip body, making it possible to easily prevent wear of the ball seat and improve the writing feel.

[0070] Examples of lubricants include higher fatty acids such as oleic acid; nonionic surfactants having a long-chain alkyl group; polyether-modified silicone oils; thiophosphite triesters such as thiophosphite tri(alkoxycarbonylmethyl ester) or thiophosphite tri(alkoxycarbonylethyl ester), phosphate monoesters of polyoxyethylene alkyl ethers or polyoxyethylene alkylaryl ethers, phosphate diesters of polyoxyethylene alkyl ethers or polyoxyethylene alkylaryl ethers, and phosphate ester surfactants such as metal salts, ammonium salts, amine salts, and alkanolamine salts of these phosphate esters.

[0071] The writing instrument ink may also contain other additives, as necessary, such as water-soluble resins, specific gravity adjusters, surfactants, pH adjusters, wetting agents, resin particles, rust inhibitors, wetting agents, defoamers, viscosity adjusters, preservatives or antifungal agents, air bubble absorbers, defoamers, antioxidants, and ultraviolet absorbers.

[0072] In the ink for writing instruments, the content of the reversible thermochromic colorant relative to the total mass of the ink composition is not particularly limited, but is preferably in the range of 5 to 40 mass%, more preferably 10 to 40 mass%, and even more preferably 10 to 30 mass%. By having the content within the above range, the desired color density can be obtained and a decrease in ink outflow can be prevented.

[0073] The ink composition can be produced by any conventionally known method. Specifically, the ink composition can be produced by mixing the above-mentioned components in required amounts and stirring them with various stirrers such as a propeller stirrer, a homodisper, or a homomixer, or dispersing them with various dispersers such as a bead mill.

[0074] Examples of writing instruments in which the writing instrument ink can be stored include various writing instruments such as ballpoint pens, marking pens, fountain pens, brush pens, and calligraphy pens.

[0075] When the writing instrument ink is used in a ballpoint pen, the structure and shape of the ballpoint pen itself are not particularly limited, and the ink may be used, for example, by filling a ballpoint pen refill or ballpoint pen equipped with a ballpoint pen tip and an ink filling mechanism.

[0076] A ballpoint pen tip is composed of a tip body and a ball provided at the front end of the tip body. Examples of ballpoint pen tips include a tip in which a ball is held by a ball holding portion formed by pressing and deforming the vicinity of the tip of a metal pipe body inward from the outer surface, a tip in which a ball is held by a ball holding portion formed by cutting a metal material with a drill or the like, a tip in which a resin ball receiving seat is provided inside a metal or plastic tip body, and a tip in which the ball held by the tip is biased forward by a spring body.

[0077] The material of the tip body and the ball is not particularly limited, and examples thereof include cemented carbide (super hard), stainless steel, ruby, ceramic, resin, rubber, etc. Furthermore, the ball can be subjected to a surface treatment such as a DLC coating.

[0078] The diameter of the ball is generally in the range of 0.2 to 3 mm, preferably 0.2 to 2 mm, more preferably 0.2 to 1.5 mm, and further preferably 0.2 to 1 mm.

[0079] An example of the ink filling mechanism is an ink reservoir that can be directly filled with ink. The ink reservoir may be a molded body made of a thermoplastic resin such as polyethylene, polypropylene, polyethylene terephthalate, or nylon, or a tubular body made of metal.

[0080] A ballpoint pen refill (hereinafter sometimes referred to as a "refill") can be formed by connecting a ballpoint pen tip directly or via a connecting member to an ink container and directly filling the ink container with ink. A ballpoint pen can be formed by storing this refill in a barrel.

[0081] The rear end of the ink reservoir is filled with an ink backflow prevention body, which may be a liquid plug or a solid plug.

[0082] The liquid plug is made of a non-volatile liquid and / or a difficult-to-volatile liquid, examples of which include petrolatum, spindle oil, castor oil, olive oil, refined mineral oil, liquid paraffin, polybutene, α-olefins, α-olefin oligomers or cooligomers, dimethyl silicone oil, methylphenyl silicone oil, amino-modified silicone oil, polyether-modified silicone oil, fatty acid-modified silicone oil, and the like. The non-volatile liquid and / or the hardly-volatile liquid can be used alone or in combination of two or more kinds.

[0083] It is preferable to add a thickener to the non-volatile liquid and / or the low-volatility liquid to thicken it to a suitable viscosity. Examples of thickeners include clay-based thickeners such as silica with a hydrophobic surface treatment, fine particle silica with a methylated surface, aluminum silicate, swellable mica, and hydrophobically treated bentonite or montmorillonite; fatty acid metal soaps such as magnesium stearate, calcium stearate, aluminum stearate, and zinc stearate; dextrin-based compounds such as tribenzylidene sorbitol, fatty acid amides, amide-modified polyethylene wax, hydrogenated castor oil, and fatty acid dextrin; and cellulose-based compounds.

[0084] Examples of solid plugs include solid plugs made of polyethylene, polypropylene, polymethylpentene, and the like. As the ink backflow preventer, a solid plug and the above-mentioned liquid plug can be used in combination.

[0085] In addition, it is also possible to form a ballpoint pen equipped with a ballpoint pen tip and an ink filling mechanism by using the barrel itself as the ink filling mechanism, filling ink directly into the barrel, and attaching a ballpoint pen tip to the front end of the barrel.

[0086] When the ink filled in the ink filling mechanism has a low viscosity, a ballpoint pen having a ballpoint pen tip and an ink filling mechanism may further include an ink supply mechanism for supplying the ink filled in the ink filling mechanism to the pen tip.

[0087] The ink supply mechanism is not particularly limited, and examples include (1) a mechanism that has an ink guide core made of a fiber bundle or the like as an ink flow rate regulator and supplies ink to the pen tip through this, (2) a mechanism that has a comb-shaped ink flow rate regulator and supplies ink to the pen tip through this, and (3) a mechanism that supplies ink to the pen tip through a pen core consisting of a number of disks arranged in parallel with comb-shaped intervals, with slit-shaped ink guide grooves running vertically through the disks in the axial direction and wider air vent grooves than the grooves, and with an ink guide core located in the axial center to guide ink from the ink filling mechanism to the pen tip.

[0088] The material for the pen core is not particularly limited as long as it is a synthetic resin that can be injection molded into a structure in which multiple disks are arranged in a comb groove shape. Acrylonitrile-butadiene-styrene copolymer (ABS resin) is preferably used because it has high moldability and is easy to obtain pen core performance.

[0089] Specific examples of the configuration of a ballpoint pen that contains ink for writing instruments include: (1) a ballpoint pen having an ink container filled with ink within a barrel, to which a ballpoint pen tip is connected directly or via a connecting member, and in which an ink backflow prevention body is filled at the end face of the ink container; (2) a ballpoint pen in which ink is directly filled within the barrel, and which is provided with a mechanism for supplying ink to the pen tip via a comb-shaped ink flow regulator or an ink guide core made of a fiber bundle or the like as an ink flow regulator; and (3) a ballpoint pen in which ink is directly filled within the barrel, and which is provided with a mechanism for supplying ink to the pen tip via the above-mentioned pen core.

[0090] When the writing instrument ink is used in a marking pen, the structure and shape of the marking pen itself are not particularly limited, and the ink may be used, for example, by filling a marking pen refill or a marking pen equipped with a marking pen tip and an ink filling mechanism.

[0091] Examples of marking pen tips include conventional porous members with interconnected pores, such as resin-processed fibers, fused heat-fusible fibers, and felt, which have a porosity selected from a range of approximately 30 to 70%, or extrusion-molded synthetic resin bodies with multiple ink outlet holes extending in the axial direction, one end of which can be processed into a bullet shape, rectangular shape, chisel shape, or other shape suited to the purpose for which it is used.

[0092] An example of the ink filling mechanism is an ink occlusion body that can be filled with ink. The ink occlusion body is a fiber bundle in which crimped fibers are bundled in the longitudinal direction, and is placed inside a plastic cylinder or a covering such as a film, with the porosity adjusted to the range of approximately 40 to 90%.

[0093] A marking pen can be formed by housing an ink occlusion body impregnated with ink inside the barrel and connecting a marking pen tip to the barrel directly or via a connecting member so as to connect to the ink occlusion body.

[0094] Also, a marking pen refill (hereinafter sometimes referred to as a "refill") can be formed by storing an ink occlusion body impregnated with ink in an ink container and connecting a marking pen tip to the ink container directly or via a connecting member so as to be connected to the ink occlusion body. A marking pen can be formed by storing this refill in a barrel.

[0095] The ink reservoir may be, for example, a molded body made of a thermoplastic resin such as polyethylene, polypropylene, polyethylene terephthalate, or nylon, or a tubular body made of metal.

[0096] A marking pen having a marking pen tip and an ink filling mechanism may further include an ink supply mechanism for supplying the ink filled in the ink filling mechanism to the pen tip.

[0097] The ink supply mechanism is not particularly limited, and examples thereof include, in addition to the ink supply mechanism provided in the ballpoint pen described above, (4) a mechanism provided with an ink flow rate regulator using a valve mechanism, which supplies ink to the pen tip by opening the valve. The valve mechanism can be of the conventional, general-purpose pumping type that opens when the tip is pressed, and is preferably set to a spring pressure that can be pressed and opened by the pressure of the writing pen.

[0098] When the marking pen is provided with an ink supply mechanism, the ink filling mechanism may be an ink reservoir that can be filled directly with ink, in addition to the ink occlusion body described above. Also, the barrel itself may serve as the ink filling mechanism, and ink may be filled directly.

[0099] Specific examples of the configuration of a marking pen that contains ink for a writing instrument include: (1) a marking pen in which an ink occlusion body consisting of a fiber bundle impregnated with ink is contained within a barrel, and a marking pen tip consisting of a fiber processed body or a resin molded body with capillary gaps formed therein is connected to the barrel directly or via a connecting member so that the ink occlusion body and the tip are connected; (2) a marking pen in which ink is directly filled into the barrel, and a mechanism is provided for supplying ink to the pen tip via a comb-shaped ink flow regulator or an ink guide core consisting of a fiber bundle or the like as an ink flow regulator; (3) a marking pen in which ink is directly filled into the barrel, and a mechanism is provided for supplying ink to the pen tip via the above-mentioned pen core; and (4) a marking pen in which the tip and an ink container are connected via a valve mechanism that opens when the tip is pressed, and ink is directly filled into the ink container.

[0100] When the ballpoint pen or marking pen according to the present invention is one in which ink is directly filled, an agitator such as an agitating ball for agitating the ink can be built into the ink reservoir or barrel in which the ink is filled in order to facilitate redispersion of the reversible thermochromic colorant. Examples of the shape of the agitator include a spherical body and a rod-shaped body. The material of the agitator is not particularly limited, and examples thereof include metal, ceramic, resin, glass, etc.

[0101] The writing instrument according to the present invention, such as a ballpoint pen or a marking pen, may be in the form of an ink cartridge as a removable structure. In this case, after the ink contained in the ink cartridge of the writing instrument is used up, the writing instrument can be used again by replacing it with a new ink cartridge.

[0102] The ink cartridges used may be those that double as the barrel of the writing instrument when connected to the main body of the writing instrument, or those that cover and protect the barrel (rear barrel) after being connected to the main body of the writing instrument. In the latter case, the ink cartridge may be used alone, or may be one in which the main body of the writing instrument and the ink cartridge are connected before use, or one that is stored in the barrel in a disconnected state so that the user of the writing instrument can connect the ink cartridge in the barrel when using the writing instrument and start using it.

[0103] A writing instrument such as a ballpoint pen or marking pen according to the present invention can be made into a capped writing instrument by providing a cap that is attached to cover the pen tip (writing tip), thereby preventing the writing tip from being contaminated or damaged. In addition, writing instruments such as ballpoint pens or marking pens that contain a refill inside the barrel can be made into retractable writing instruments by providing a retraction mechanism inside the barrel that allows the writing tip to protrude and retract from the barrel, thereby preventing the writing tip from becoming contaminated or damaged.

[0104] Any retractable writing instrument can be used as long as the writing tip is housed within a barrel with the writing tip exposed to the outside air and the retractable mechanism is activated to cause the writing tip to protrude from the barrel opening. It may also be a composite type retractable writing instrument in which a plurality of refills are housed within the barrel, and the writing tip of any one of the refills is caused to protrude and retract from the barrel opening by operation of a retraction mechanism.

[0105] Examples of the retraction mechanism include: (1) a side-slide type retraction mechanism in which an operating part (clip) that can move in the front-rear direction protrudes radially outward from the rear side wall of the barrel, and the operating part is slid forward to cause the writing tip to appear and disappear from the front opening of the barrel; (2) a rear-end knock type retraction mechanism in which an operating part provided at the rear end of the barrel is pressed forward to cause the writing tip to appear and disappear from the front opening of the barrel; (3) a side-knock type retraction mechanism in which an operating part protruding from the outer surface of the side wall of the barrel is pressed radially inward to cause the writing tip to appear and disappear from the front opening of the barrel; and (4) a rotating type retraction mechanism in which an operating part at the rear of the barrel is rotated to cause the writing tip to appear and disappear from the front opening of the barrel.

[0106] The shape of the ballpoint pen or marking pen is not limited to the configuration described above, and it may be equipped with tips of different shapes, or with tips that dispense ink of different tones or hues, or it may be a composite writing instrument (double-headed, retractable tip, etc.) in which tips of different shapes are attached and the ink dispensed from each tip has a different color tone or hue.

[0107] The handwriting obtained by writing on a surface to be written on using a writing instrument containing the above-mentioned ink for a writing instrument can be discolored by rubbing with a finger or by using a heating or cooling tool.

[0108] Examples of the heating device include an electrically-heated discoloring device equipped with a resistive heating element such as a PTC element, a heat discoloring device filled with a medium such as hot water, a heat discoloring device using steam or laser light, and the application of a hair dryer. However, friction members and friction bodies are preferred because they can change color in a simple manner. Examples of cooling devices include electrically-operated thermochromic devices using a Peltier element, thermochromic devices filled with a refrigerant such as cold water or ice chips, cooling agents, refrigerators, or freezers.

[0109] As the friction member and friction body, elastic bodies such as elastomers and plastic foams that are rich in elasticity and can generate appropriate friction and generate frictional heat when rubbed are preferred, but plastic molded bodies, stone materials, wood, metals, fabrics, etc. can also be used. Note that, although a general eraser used for erasing pencil marks may be used to rub the marks, eraser shavings are generated during rubbing, the above-mentioned friction members and friction bodies that generate almost no eraser shavings are preferably used.

[0110] Examples of the material of the friction member and the friction body include silicone resin, styrene-ethylene-butadiene-styrene block copolymer (SEBS resin), etc. Silicone resin is likely to adhere to the part erased by rubbing, and handwriting tends to be repelled when writing is repeated, so SEBS resin is more preferably used.

[0111] The friction member or friction body may be a member of any shape that is separate from the writing instrument, but by providing it on the writing instrument, the writing instrument can be made highly portable. Also, a writing instrument set can be obtained by combining a writing instrument with a friction member or friction body of any shape that is separate from the writing instrument.

[0112] In the case of a writing instrument with a cap, the location where the friction member or friction body is provided is not particularly limited. For example, the cap itself may be formed from a friction member, the barrel itself may be formed from a friction member, and if a clip is provided, the clip itself may be formed from a friction member, or the friction member or friction body may be provided at the tip (top) of the cap or the rear end of the barrel (the part where the writing tip is not provided), etc.

[0113] In the case of a writing instrument equipped with a retractable mechanism, the location where the friction member or friction body is provided is not particularly limited, and for example, the barrel itself may be formed from a friction member, and if a clip is further provided, the clip itself may be formed from a friction member, or the friction member or friction body may be provided near the opening of the barrel, at the rear end of the barrel (the portion where the writing tip is not provided), or in the knock portion, etc.

[0114] The ink composition according to the present invention can be used as an ink for stamps. The stamp vehicle used in the stamp ink may be an oil-based vehicle containing an organic solvent, or an aqueous vehicle containing water and, if necessary, an organic solvent.

[0115] Examples of the organic solvent include castor oil fatty acid alkyl esters, cellosolve-based solvents, alkylene glycol-based solvents, ester-based solvents, hydrocarbon-based solvents, halogenated hydrocarbon-based solvents, alcohol-based solvents, ether-based solvents, ketone-based solvents, propionic acid-based solvents, highly polar solvents, and mixed solvents thereof.

[0116] When the vehicle is an aqueous vehicle, the ink for stamping may contain a water-soluble organic solvent that is compatible with water. The water-soluble organic solvent is preferably glycerin or propylene glycol.

[0117] When the ink for stamping contains a water-soluble organic solvent, the content of the water-soluble organic solvent relative to the total mass of the ink composition is not particularly limited, but is preferably in the range of 30 to 60 mass%, more preferably 30 to 55 mass%, and even more preferably 40 to 50 mass%. By having the content within the above range, the ink does not dry out or absorb moisture, making it easier to obtain a clear print.

[0118] A thickener can be blended into the ink for stamping, which can suppress aggregation and / or sedimentation of the reversible thermochromic colorant and can also suppress bleeding of the printed image, thereby enabling the formation of a clear printed image. As the thickener, any known substance can be used, but an alkali-soluble acrylic emulsion is preferred. When an alkali-soluble acrylic emulsion is used as the thickener, the pH of the ink for stamping is preferably in the range of 6-11, more preferably 7-11, and even more preferably 7-10.

[0119] Stamp ink can contain a binder resin to improve the adhesion of the print image and adjust the viscosity. Examples of the binder resin include a resin emulsion, an alkali-soluble resin, and a water-soluble resin.

[0120] The stamp ink may also contain other additives, such as surfactants, pH adjusters, wetting agents, resin particles, rust inhibitors, wetting agents, defoamers, viscosity adjusters, preservatives or antifungal agents, air bubble absorbers, defoamers, antioxidants, and ultraviolet absorbers, as required.

[0121] In the ink for stamps, the content of the reversible thermochromic colorant relative to the total mass of the ink composition is not particularly limited, but is preferably in the range of 10 to 40 mass%, more preferably 10 to 35 mass%, and even more preferably 10 to 30 mass%. If the content exceeds 40 mass%, the dispersion stability of the reversible thermochromic colorant in the ink tends to decrease. On the other hand, if the content is less than 10 mass%, the color density tends to decrease.

[0122] The ink for stamps can be used as ink for stamp pads and ink for stamps equipped with a printing material having continuous pores. For example, a stamp pad can be impregnated with ink to obtain a stamp pad that supplies ink to the printing surface of a stamp that is brought into contact with the stamp pad, or a stamp can be obtained by impregnating ink into the printing material of a stamp having continuous pores.

[0123] The stamp can form an image on various surfaces. Furthermore, the image formed on the surface using the stamp containing the ink for stamping can be discolored by rubbing with a finger or by the above-mentioned heating or cooling tool. The above-mentioned friction member and friction body are preferable as the heating tool, since they can be discolored by a simple method.

[0124] The above-mentioned friction member or friction body may be a member of any shape separate from the stamp, but by providing it on the stamp, it is possible to make the stamp highly portable. Also, a stamp set can be obtained by combining a stamp with a friction member or friction body of any shape separate from the stamp.

[0125] When the ink composition according to the present invention is used by printing or coating, the material of the support to be printed or coated is not particularly limited and all materials are effective, and examples thereof include paper, synthetic paper, fiber, cloth, synthetic leather, leather, plastic, glass, ceramic material, metal, wood, stone material, etc. The shape of the support is not limited to a flat shape, but may be uneven.

[0126] By providing a reversible thermochromic layer made of a reversible thermochromic liquid composition on a support, a reversible thermochromic laminate (reversible thermochromic printed matter) can be obtained. This laminate (printed matter) reversibly changes color in response to a change in temperature. In addition, in the case of a support on which a non-color-changing colored layer (non-color-changing colored image) has already been formed, by providing a reversible thermochromic layer on the non-color-changing colored layer, the non-color-changing colored layer (non-color-changing colored image) can be made to appear or disappear by the reversible thermochromic layer due to a change in temperature, thereby further diversifying the manner of change.

[0127] The reversible thermochromic colorant according to the present invention can be melt-blended with an excipient and molded into a solid molded article for application, which can be used as a solid writing material or a solid cosmetic material. Examples of solid writing materials include crayons, pencil leads, mechanical pencil leads, solid gel markers, and the like. Examples of solid cosmetics include foundation, eyeliner, eyebrow cream, eyeshadow, lipstick, etc.

[0128] Examples of excipients used in the solid writing material include wax, gelling agents, clay minerals, etc. Among these excipients, it is preferable to contain at least one selected from the group consisting of polyolefin wax, sucrose fatty acid ester, and dextrin fatty acid ester, since this easily improves the writing density.

[0129] The content of the excipient relative to the total mass of the solid writing material is not particularly limited, but is preferably in the range of 0.2 to 70% by mass, more preferably 0.5 to 40% by mass. When the content is within the above range, the shape of the solid writing material can be easily obtained, and the writing density of the solid writing material can easily be increased.

[0130] The solid writing material may also contain additives such as fillers, binder resins, viscosity modifiers, preservatives or antifungal agents, antibacterial agents, antioxidants, ultraviolet light inhibitors, lubricants, and fragrances, if necessary.

[0131] The solid writing material may be used alone as a writing material, or may be used as an inner core with an outer shell covering the outer periphery thereof to form a core-sheath structure (double core).

[0132] The solid writing material can be used to write on various writing surfaces. Furthermore, the writing marks formed on the writing surface using the solid writing material can be discolored by rubbing with a finger or by the above-mentioned heating or cooling tool. Since the color can be discolored by a simple method, the above-mentioned friction member and friction body are preferable as the heating tool.

[0133] The friction member or friction body may be a member of any shape separate from the solid writing body or the exterior of the solid writing implement in which the solid writing body is housed in an exterior container, but by providing it on the exterior of the solid writing body or the solid writing implement, it can be made highly portable.Specific examples include a form in which the friction member is provided on an exterior in the shape of a pencil, crayon, etc., made of wood or paper.In addition, a solid writing body set can be obtained by combining the solid writing body with a friction member or friction body of any shape separate from the solid writing body.

[0134] The reversible thermochromic colorant according to the present invention can be melt-blended with thermoplastic resins, thermosetting resins, waxes, etc. to form pellets, powder, or paste, and used as a molding resin composition. Using the above-mentioned molding resin composition, molded articles in the form of three-dimensional objects of any shape, films, sheets, plates, filaments, rods, pipes, etc. can be obtained by general-purpose means such as injection molding, extrusion molding, blow molding, cast molding, etc. Moreover, by melt-blending it with a thermoplastic resin, a toner or powder coating material can be obtained.

[0135] By blending the above-mentioned liquid composition, solid molding for coating, and resin composition for molding with a non-discoloring colorant such as a general dye or pigment, it is possible to make them exhibit a discoloration behavior from colored (1) to colored (2).

[0136] Specific examples of products using the reversible thermochromic composition according to the present invention and the reversible thermochromic microcapsule pigment or resin particles encapsulating the same include the following. (1)Toys Dolls and animal-shaped toys; hair for dolls and animal-shaped toys; doll houses and furniture, clothing, hats, bags, shoes and other doll accessories; accessory toys; stuffed toys; drawing toys; toy picture books; puzzle toys such as jigsaw puzzles; building block toys; building blocks; clay toys; fluid toys; tops; kites; musical instrument toys; cooking toys; gun toys; capture toys; background toys; mask toys; toys imitating vehicles, animals, plants, buildings, food, etc., (2) Clothing Clothing such as T-shirts, sweatshirts, blouses, dresses, swimsuits, raincoats, skiwear, etc.; footwear such as shoes; shoelaces; shoe components such as insoles, outsoles, midsoles, etc.; cloth personal items such as handkerchiefs, towels, wrapping cloths, etc.; gloves; ties; hats; sportswear, etc. (3) Indoor decorations Carpets, curtains, curtain strings, tablecloths, rugs, cushions, seat cushions, chair upholstery, seats, mats, picture frames, artificial flowers, photo frames, etc. (4) Furniture Bedding such as futons, pillows, mattresses, chairs, zaisu chairs, sofas, lighting equipment, heating and cooling equipment, etc. (5) Decorations Rings, bracelets, tiaras, necklaces, earrings, hair clips, false nails, ribbons, scarves, watches, glasses, key chains, etc. (6) Stationery Writing implements, stamps, erasers, writing pads, rulers, planners, notebooks, adhesive tape, etc. (7)Daily necessities Toiletries such as disposable diapers; bath supplies; toothbrushes; cooling or heat-retaining bags; hand warmers; thermometers; watering cans; buckets; cleaning equipment; cosmetics such as lipstick, eye shadow, foundation, eyeliner, eyebrows, nail polish, hair dye, and false nail paint, etc. (8) Kitchen utensils Cooking utensils, lunch boxes, water bottles, cups, plates, chopsticks, spoons, forks, pots, frying pans, coasters, trivets, placemats, etc. (9)Other Calendars, labels, cards, recording materials, various printed materials to prevent counterfeiting; picture books and other books; sporting equipment such as gloves, protectors, nets, etc.; bags; packaging containers; embroidery thread; fishing gear; musical instruments; ice packs; bags such as wallets; umbrellas; vehicles; buildings; temperature detection indicators; teaching equipment such as picture books and maps; pet supplies: medical or nursing supplies such as supports, bandages, bandages, etc., electronic devices such as smartphones, earphones, speakers, etc. EXAMPLES

[0137] Examples are shown below. In the examples, "parts" refers to "parts by mass" unless otherwise specified.

[0138] Example 101 As the (a) component, 2-(di-n-butylamino)-8-(di-n-pentylamino)-4-methyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1'(3'H)-isobenzofuran]-3'-one (A-1) 1 part, as the (b) component, 1,1-bis(4-hydroxyphenyl)-2-methylpropane (Ba-1) 1.25 parts, 4-(1',3',4',9'a-tetrahydro-6'-hydroxy-spiro[cyclohexane-1,9'-[9H]-xanthene]-4'a(2'H)-yl)-1,3-benzenediol (Bb-1) 3.75 parts, as the (c) component, a reversible thermochromic composition consisting of 3-methylbutyl behenate (C-1) 50 parts was encapsulated in microcapsules by interfacial polymerization to prepare a microcapsule dispersion. The above microcapsule dispersion was centrifuged to obtain a reversible thermochromic microcapsule pigment, which reversibly changed color from pink to colorless.

[0139] Examples 102 to 105 and Comparative Examples 101 to 103 A reversible thermochromic microcapsule pigment was obtained in the same manner as in Example 1, except that the types and amounts of components (a), (b), and (c) were changed to those shown in Table 1 below. Each of the resulting microcapsule pigments reversibly changed color from pink to colorless.

[0140] [Concentration measurement] A reversible thermochromic ink was prepared by mixing 40 parts of each of the microcapsule pigments of Examples 101 to 105 and Comparative Examples 101 to 103, 52 parts of an ethylene-vinyl acetate copolymer resin emulsion, 5 parts of a thickener, and 3 parts of a leveling agent. A solid pattern was screen-printed on fine paper using the ink to obtain a sample for density measurement. Each of the above measurement samples was cooled to below the full color development temperature t1 to reach a fully colored state, and then set in the measurement section of a fluorescence spectrodensitometer (manufactured by Konica Minolta, Inc., product name: FD-7 type) to measure the absolute density in the fully colored state (hereinafter sometimes referred to as "color development density"). Next, each measurement sample that had been subjected to the above measurements was heated to a temperature equal to or higher than the complete decolorization temperature t4 to be in a completely decolorized state, and then each measurement sample was set in the measurement portion of the above-mentioned fluorescence spectrodensitometer, and the absolute density in the completely decolorized state (hereinafter sometimes referred to as the "decolorization density") was measured. Furthermore, the contrast (density difference) [(color density)-(decolor density)] was calculated from the obtained color density and decolor density. The results obtained are shown in Table 1 below.

[0141] [Discoloration temperature measurement] A reversible thermochromic ink was prepared by mixing 40 parts of each of the microcapsule pigments obtained in Examples 101 to 105 and Comparative Examples 101 to 103, 52 parts of an ethylene-vinyl acetate copolymer resin emulsion, 5 parts of a thickener, and 3 parts of a leveling agent. A solid pattern was screen-printed on high-quality paper using the ink to obtain a sample for measuring the color change temperature. Each discoloration temperature measurement sample was set in the measurement section of a color difference meter (Tokyo Denshoku Co., Ltd., product name: TC-3600), and the temperature of the sample section was raised and lowered at a rate of 2°C / min, and the brightness value was measured as the color density at each temperature, and a color density-temperature curve was created. From the color density-temperature curve, the complete color development temperature t1, color development start temperature t2, decolorization start temperature t3, and complete decolorization temperature t4 were obtained. Furthermore, from the obtained t1, t2, t3, and t4, the hysteresis width (ΔH), the difference between the color development start temperature t2 and the complete color development temperature t1 (t2-t1), and the difference between the complete decolorization temperature t4 and the decolorization start temperature t3 (t4-t3) were calculated. The results obtained are shown in Table 1 below.

[0142] The numerical values ​​for components (a), (b), and (c) in the table indicate "parts by mass," and the numerical values ​​for complete color development temperature t1, color development start temperature t2, color fade start temperature t3, complete fade temperature t4, hysteresis width (ΔH), the difference between color development start temperature t2 and complete color development temperature t1 (t2-t1), and the difference between complete fade temperature t4 and fade fade start temperature t3 (t4-t3) are indicated in "°C." [Table 1]

[0143] Components (a), (b), and (c) in the table are the compounds shown below. A-1 2-(di-n-butylamino)-8-(di-n-pentylamino)-4-methyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one Ba-1 1,1-bis(4-hydroxyphenyl)-2-methylpropane Ba-2 1,1-bis(4-hydroxyphenyl)-2-ethylhexane Ba-3 1-phenyl-1,1-bis(4-hydroxyphenyl)ethane Bb-1 4-(1′,3′,4′,9′a-tetrahydro-6′-hydroxy-spiro[cyclohexane-1,9′-[9H]-xanthene]-4′a(2′H)-yl)-1,3-benzenediol C-1 3-Methylbutyl behenate

[0144] Example 201 As the component (a), 2-(di-n-butylamino)-8-(di-n-pentylamino)-4-methyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1'(3'H)-isobenzofuran]-3'-one (A-1) 1 part, as the component (b), 1-phenyl-1,1-bis(4-hydroxyphenyl)ethane (Ba-3) 2.5 parts, 4-(1',3',4',9'a-tetrahydro-6'-hydroxy-spiro[cyclohexane-1,9'-[9H]-xanthene]-4'a(2'H)-yl)-1,3-benzenediol (Bb-1) 2.5 parts, and as the component (c), stearate neopentyl (C-2) 50 parts were mixed and dissolved by heating to obtain a reversible thermochromic composition that reversibly changes color from pink to colorless.

[0145] Examples 202 to 206 A reversible thermochromic microcapsule pigment was obtained in the same manner as in Example 101, except that the types and amounts of components (a), (b), and (c) were changed to those shown in Table 2 below. Each of the resulting microcapsule pigments reversibly changed color from pink to colorless.

[0146] Comparative Example 201 As component (a), 1 part of 2-(di-n-butylamino)-8-(di-n-pentylamino)-4-methyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1'(3'H)-isobenzofuran]-3'-one (A-1), as component (b), 5 parts of 1-phenyl-1,1-bis(4-hydroxyphenyl)ethane (Ba-3), as component (c), and 50 parts of neopentyl stearate (C-2) were mixed and dissolved by heating to obtain a reversible thermochromic composition that reversibly changes color from pink to colorless.

[0147] Comparative Example 202 A reversible thermochromic composition that reversibly changes color from pink to colorless was obtained in the same manner as in Comparative Example 101, except that the types and amounts of components (a), (b), and (c) were changed to those shown in Table 2 below.

[0148] Comparative Examples 203 to 206 A reversible thermochromic microcapsule pigment was obtained in the same manner as in Example 101, except that the types and amounts of components (a), (b), and (c) were changed to those shown in Table 2 below. Each of the resulting microcapsule pigments reversibly changed color from pink to colorless.

[0149] [Concentration measurement] Each of the reversible thermochromic compositions obtained in Example 201 and Comparative Examples 201 and 202 was dropped onto a filter paper (manufactured by Toyo Roshi Kaisha, Ltd., product name: Qualitative Filter Paper No. 2) to obtain a sample for concentration measurement. In addition, 40 parts of each of the microcapsule pigments obtained in Examples 202 to 206 and Comparative Examples 203 to 206, 52 parts of an ethylene-vinyl acetate copolymer resin emulsion, 5 parts of a thickener, and 3 parts of a leveling agent were mixed to prepare a reversible thermochromic ink. A solid pattern was screen-printed on fine paper using the ink to obtain a sample for density measurement. Each of the above measurement samples was cooled to below the full color development temperature t1 to reach a fully colored state, and then set in the measurement portion of a fluorescence spectrodensitometer (manufactured by Konica Minolta, Inc., product name: FD-7 type) to measure the color development density. Next, each measurement sample that had been subjected to the above measurements was heated to a complete decolorization temperature t4 or higher to be in a completely decolorized state, and then each measurement sample was set in the measurement portion of the above-mentioned fluorescence spectrodensitometer to measure the decolorization density. Furthermore, the contrast (density difference) [(color density)-(decolor density)] was calculated from the obtained color density and decolor density. The results obtained are shown in Table 2 below.

[0150] The numerical values ​​for components (a), (b), and (c) in the table indicate "parts by mass," and the numerical values ​​for complete color development temperature t1, color development start temperature t2, color fade start temperature t3, complete fade temperature t4, hysteresis width (ΔH), the difference between color development start temperature t2 and complete color development temperature t1 (t2-t1), and the difference between complete fade temperature t4 and fade fade start temperature t3 (t4-t3) are indicated in "°C." [Table 2]

[0151] Components (a), (b), and (c) in the table are the compounds shown below. A-1 is the same as above. A-2 2-(di-n-butylamino)-8-(N-ethyl-Ni-amylamino)-4-phenyl-spiro[5H-(1)benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one Ba-1, Ba-2, and Ba-3 are the same as above. Bb-1 is the same as above. Bb-2 4-(1′,3′,4′,9′a-tetrahydro-6′-hydroxy-7′-methyl-spiro[cyclohexane-1,9′-[9H]-xanthene]-4′a(2′H)-yl)-6-methyl-1,3-benzenediol C-1 is the same as above. C-2 Neopentyl stearate C-3 1-Hexadecanol

[0152] Preparation of reversible thermochromic microencapsulated pigment A As the (a) component, 2-(di-n-butylamino)-8-(di-n-pentylamino)-4-methyl-spiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1'(3'H)-isobenzofuran]-3'-one 1 part, as the (b) component, 1,1-bis(4-hydroxyphenyl)-2-methylpropane 2.5 parts, 4-(1',3',4',9'a-tetrahydro-6'-hydroxy-spiro[cyclohexane-1,9'-[9H]-xanthene]-4'a(2'H)-yl)-1,3-benzenediol 2.5 parts, as the (c) component, butyl stearate 30 parts, behenic acid 3,5,5-trimethylhexyl 20 parts were encapsulated in microcapsules by interfacial polymerization to prepare a microcapsule dispersion. From the above microcapsule dispersion, a reversible thermochromic microcapsule pigment A was obtained by centrifugal separation. Microcapsule pigment A was pink in the temperature range below 25°C and colorless in the temperature range of 25°C or higher, and this color change was reversible.

[0153] Preparation of reversible thermochromic microencapsulated pigment B As the (A) component, 1.5 parts of 3-(2-ethoxy-4-diethylaminophenyl)-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide, as the (B) component, 2.5 parts of 1,1-bis(4-hydroxyphenyl)-2-methylpropane, 2.5 parts of 4-(1',3',4',9'a-tetrahydro-6'-hydroxy-spiro[cyclohexane-1,9'-[9H]-xanthene]-4'a(2'H)-yl)-1,3-benzenediol, as the (C) component, 10 parts of butyl stearate, and 40 parts of 3,5,5-trimethylhexyl behenate were encapsulated in microcapsules by interfacial polymerization to prepare a microcapsule dispersion. From the above microcapsule dispersion, a reversible thermochromic microcapsule pigment B was obtained by centrifugation. Microencapsulated pigment B was blue in the temperature range below 30°C and colorless in the temperature range of 30°C or higher, and this color change was reversible.

[0154] Preparation of reversible thermochromic microencapsulated pigment C A reversible thermochromic composition consisting of 1.5 parts of 3-(2-ethoxy-4-diethylaminophenyl)-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide as component (A), 5 parts of 2,2-bis(4-hydroxyphenyl)hexafluoropropane as component (B), and 50 parts of neopentyl stearate as component (C) was encapsulated in microcapsules by interfacial polymerization to prepare a microcapsule dispersion. From the above microcapsule dispersion, a reversible thermochromic microcapsule pigment C was obtained by centrifugation. Microencapsulated pigment C was blue in the temperature range of 13° C. or less and colorless in the temperature range of 33° C. or more, and this color change was reversible. In addition, it was possible to maintain either of the above colors in the temperature range of more than 16° C. and less than 28° C.

[0155] Application example 1 Fabrication of reversible thermochromic flocked objects (reversible thermochromic animal-shaped toys) 7 parts of the reversible thermochromic microcapsules A, 0.1 parts of a blue general pigment, 2 parts of a dispersant, and 91 parts of nylon 12 having a melting point of 180°C were melt-mixed in an extruder at 200°C to prepare a reversible thermochromic molding resin composition in the form of pellets. The above pellets were fed to an extrusion molding machine, spun from 32 discharge holes at 200° C., and wound up at a draw ratio of 2 to obtain a drawn yarn of 224 denier / 32 filaments. The obtained filaments were further bundled and spooled, then cut into a cut length of 1.5 mm using a pile cutter, and further subjected to electrodeposition treatment and drying to obtain a thermochromic pile. The above-mentioned thermochromic pile was used to implant the hairs into a vinyl chloride rabbit-shaped animal-shaped toy (hereinafter sometimes referred to as a "rabbit toy") that had been pre-coated with adhesive, using an electrostatic hair implantation device, and then dried to produce a reversible thermochromic flocked body (reversible thermochromic animal-shaped toy). The rabbit toy was purple in the temperature range below 25°C and blue in the temperature range above 25°C, and this color change was reversible. In addition, this reversible color change was sensitive, and the toy changed color with high sensitivity.

[0156] Application example 2 Fabrication of a doll toy with hair using reversible thermochromic composite fiber 2.5 parts of the reversible thermochromic microencapsulated pigment A, 2.5 parts of the reversible thermochromic microencapsulated pigment B, 1 part of a dispersant, and 94 parts of a polypropylene-ethylene copolymer having a melting point of 135°C were melt-mixed at 200°C in an extruder to prepare a reversible thermochromic molding resin composition in the form of pellets for the core. The above pellets were fed to an extruder for forming the core, and 6-12 copolymer nylon natural pellets with a melting point of 145°C were fed to an extruder for forming the sheath. Using a composite fiber spinning device, the fibers were spun at 200°C from 18 discharge holes so that the volume ratio of core:sheath was 6:4, to prepare a reversible thermochromic composite fiber consisting of 18 single yarns with an outer diameter of 90 μm. Furthermore, the reversible thermochromic composite fiber was implanted on the head of a doll by a conventional method (for example, a hair implantation sewing machine) to produce a doll toy equipped with hair made of the reversible thermochromic composite fiber. The hair provided to the doll toy was purple in the temperature range below 25°C, blue in the temperature range between 25°C and 30°C, and white in the temperature range above 30°C, and this color change was reversible. In addition, this reversible color change was sensitive, and the hair changed color with high sensitivity.

[0157] Application example 3 Fabrication of a reversible thermochromic toy (reversible thermochromic miniature car) A reversible thermochromic liquid composition, which is a paint used for spray painting, was prepared by stirring and mixing 7.5 parts of the reversible thermochromic microcapsule pigment A, 7.5 parts of the reversible thermochromic microcapsule pigment C, and 0.1 parts of a yellow general pigment in a vehicle consisting of 40 parts of an acrylic resin / xylene solution, 20 parts of xylene, 20 parts of methyl isobutyl ketone, and 5 parts of a polyisocyanate-based hardener. The entire body of a white miniature car made by injection molding ABS resin as a support was spray-painted with the above-mentioned paint and dried to create a reversible thermochromic layer, producing a reversible thermochromic toy (reversible thermochromic miniature car). When the reversible thermochromic toy was cooled to below 13°C, it turned brown, and remained brown as long as it was kept below 25°C. At temperatures between 25°C and 28°C, it turned green, at temperatures above 33°C, it turned yellow, and remained yellow as long as it was kept above 25°C. At temperatures between 16°C and 25°C, it turned orange, and at temperatures below 13°C, it turned brown again. This color change was reversible, and by heating or cooling the toy and placing it within a specific temperature range, different colors such as brown, green, yellow, and orange could be produced, and the toy had a charm of change and unexpectedness, making it an excellent product. In addition, this reversible color change was sensitive, and the toy changed color with high sensitivity.

[0158] Application example 4 Fabrication of doll clothes using reversible thermochromic mohair yarn 5 parts of the reversible thermochromic microcapsule pigment A, 1 part of the dispersant, and 94 parts of nylon 12 having a melting point of 180°C were melt-mixed in an extruder at 200°C to prepare a reversible thermochromic molding resin composition in the form of pellets. The above pellets were fed into an extruder and spun from 36 nozzle holes at 200° C. using a general-purpose melt spinning device to prepare a reversible thermochromic fiber consisting of 36 single yarns with an outer diameter of 30 μm. Furthermore, reversibly thermochromic mohair yarn was prepared by a conventional method using the reversibly thermochromic fiber as a filament yarn and two 250 denier polyester yarns as core yarns, adjusting the filament yarn length to 10 mm. The mall yarn had a soft feel and was pink in the temperature range below 25° C. and white in the temperature range above 25° C., and this color change was reversible. In addition, this reversible color change was sensitive, and the mall yarn changed color with high sensitivity. When this mohair yarn was sewn onto a part of a doll's clothing as an ornament, the ornament had an appearance similar to that of high pile fabric for stuffed toys and also showed the same color change as that described above. [Explanation of symbols]

[0159] t1 full color temperature t2 color development start temperature t3 decolorization start temperature t4 complete color erasure temperature ΔH Hysteresis width

Claims

1. (i) As electron-donating chromogenic organic compounds, the compound represented by the following formula (A) and (b) As electron-accepting compounds, a combination of the compound represented by the following formula (Ba) and the compound represented by the following formula (Bb), (c) A reaction medium that causes an electron transfer reaction between components (a) and (b) to occur reversibly in a specific temperature range. A reversible thermochromic composition comprising the following: 【Chemistry 1】 (In the formula, R １１ and R １２ Each of these is independently a hydrogen atom; a C1-C8 alkyl group which may be substituted with a hydroxyl group; a C2-C12 alkoxyalkyl group; a C4-C11 carboalkoxyalkyl group; a C7-C12 phenylalkyl group; or a phenyl group which may be substituted with a halogen atom, a C1-C4 alkyl group, or a C1-C4 alkoxy group. However, R １１ and R １２ They may together form a ring, R １３ and R １４ Each of these is independently a hydrogen atom; a C1-C8 alkyl group which may be substituted with a hydroxyl group; a C5-C7 cycloalkyl group; a C2-C12 alkoxyalkyl group; a C4-C11 carboalkoxyalkyl group; and a C7-C12 phenylalkyl group. However, R １３ and R １４ They may together form a ring, R １５ is an alkyl group having 1 to 3 carbon atoms; an alkoxy group having 1 to 4 carbon atoms; a phenyl group which may be substituted by any one of a halogen atom, an alkyl group having 1 to 4 carbon atoms, and an alkoxy group having 1 to 4 carbon atoms, R １６ and R １７ Each is independently a halogen atom; a C1-C3 alkyl group which may be substituted with a hydroxyl group or a halogen atom. n16 is an integer between 0 and 3. n17 is an integer between 0 and 4. 【Chemistry 2】 (In the formula, R ａ１ and R ａ２ Each is independently a hydrogen atom; a C1-C17 alkyl group which may be substituted with a fluorine atom (where the methylene group in the alkyl group is (-CH) ２ (-) may be replaced by an oxy group (-O-) or a carbonyl group (-CO-); an aryl group having 6 to 10 carbon atoms, R ａ３ and R ａ４ Each of these is independently a C1-C4 alkyl group which may be substituted with a fluorine atom or a hydroxyl group; a C2-C4 alkenyl group; and a halogen atom. na3 and na4 are each independent integers between 0 and 2. 【Transformation 3】 (In the formula, R ｂ１ This is a hydroxyl group or an alkyl group having 1 to 10 carbon atoms (however, R ｂ１ (at least one of them is a hydroxyl group) R ｂ２ This is an alkyl group having 1 to 10 carbon atoms. nb1 is an integer between 1 and 4. nb2 is an integer between 0 and 3.

2. The aforementioned R ａ１ and R ａ２ The reversible thermochromic composition according to claim 1, wherein at least one of the members is an alkyl group having 1 to 9 carbon atoms, or a phenyl group.

3. The aforementioned R ｂ１ The reversible thermochromic composition according to claim 1, wherein is a hydroxyl group and nb1 is 1.

4. The reversible thermochromic composition according to claim 1, wherein the mass ratio of the compound represented by formula (Ba) to the compound represented by formula (Bb) is 2:8 to 8:

2.

5. The reversible thermochromic composition according to claim 1, wherein the component (c) is an ester compound exhibiting a ΔT value (melting point - cloud point) of 3°C or less.

6. The reversible thermochromic composition according to claim 1, 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 a reversible thermochromic composition according to any one of claims 1 to 6.

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 coloring liquids.

10. A solid writing instrument or solid cosmetic comprising the reversible thermochromic microcapsule pigment described in claim 7 and an excipient.

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

12. A reversible thermochromic molded article obtained by molding the reversible thermochromic molded resin composition according to claim 11.

13. 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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