Reversibly thermochromic composition, writing utensil using said reversibly thermochromic composition, and toy

Abstract

The present invention addresses the problem of providing: a reversibly thermochromic composition which achieves a good balance between excellent color developing sensitivity and decoloring properties, while having a non-phenolic structure that places little burden on the human body or the environment; a writing utensil which contains this reversibly thermochromic composition; and a toy which comprises this reversibly thermochromic composition.　The problem is solved by a reversibly thermochromic composition which contains a color developer that contains a compound represented by formula (1), a leuco dye and a color change temperature regulator. (In formula (1), a, a', b, A, A' and X are as follows: a represents an integer selected from among 0 to 5; a' represents an integer selected from among 0 to 5; b represents 0 or 1; X represents -C(=Y)- or -SO2-; the sum of a and a' is not less than 1; each of A and A' independently represents an electron-withdrawing group or a hydrogen-bonding group; and Y represents O or S. Meanwhile, a benzene ring in formula (1) may have a substituent other than A and A'.)

Description

Reversible thermochromic composition, writing implement and toy using said reversible thermochromic composition

[0001] The present invention relates to a reversible thermochromic composition, a writing instrument containing the reversible thermochromic composition, and a toy including the reversible thermochromic composition.

[0002] The reversible thermochromic composition mainly comprises a basic (electron-donating) leuco dye (hereinafter sometimes abbreviated as "leuco dye"), an electron-accepting color developer (hereinafter sometimes abbreviated as "color developer"), and a color change temperature regulator. The color change temperature regulator controls the switching between the colorless state and the colored state by reversibly inducing an electron donor-acceptor reaction between the leuco dye and the color developer within a specific temperature range (see, for example, Patent Document 1).

[0003] The color developer contained in the reversible thermochromic composition is often a compound mainly having a bisphenol structure, such as 2,2-bis(4-hydroxyphenyl)propane (bisphenol A), 2,2-bis(4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane (bisphenol AF), etc. However, from the viewpoint of the influence of the bisphenol structure on environmental hormones, etc., it is considered preferable to use a compound that does not have a bisphenol structure or a phenol structure as a color developer.

[0004] Patent Documents 2, 3 and 4 disclose reversible thermochromic compositions containing diphenylurea or diphenylthiourea as color developers having neither a bisphenol structure nor a phenol structure.

[0005] JP 2005-213361 A JP 62-140881 A JP 62-079283 A JP 62-101684 A

[0006] As described above, there is a need for the development of color developers that are less harmful to the human body and the environment than compounds primarily having a bisphenol structure or a phenol structure. Furthermore, the present inventors have prepared reversible thermochromic compositions using the color developers disclosed in Patent Documents 2 to 4 and evaluated their color development sensitivity and decolorization properties, but found that they did not exhibit sufficient color development sensitivity or decolorization properties. In other words, an object of the present invention is to provide a reversible thermochromic composition that has a non-phenolic structure that is less harmful to the human body and the environment and that combines excellent color development sensitivity and decolorization properties, as well as a writing instrument containing the reversible thermochromic composition and a toy that includes the reversible thermochromic composition.

[0007] As a result of extensive investigations, the present inventors have found that the above problems can be solved by using a compound having a specific structure as a developer.

[0008] [1] A reversible thermochromic composition comprising a color developer containing a compound represented by the following formula (1), a leuco dye, and a color change temperature regulator: (In the above formula (1), a, a', b, A, A', and X are as follows: a is an integer selected from 0 to 5; a' is an integer selected from 0 to 5; b is 0 or 1; X is -C(=Y)- or -SO ２-, the sum of a and a' is 1 or more, A and A' are each independently an electron-withdrawing group or a hydrogen-bonding group, and Y is O or S. However, the benzene ring in the above formula (1) may have a substituent other than A or A'.) [2] The reversible thermochromic composition according to [1], wherein in the formula (1), at least one A or A' is an electron-withdrawing group selected from a halogen atom, a nitrile group, a carboxyl group, an alkyl group having at least one fluoro group, and an oxycarbonyl group, carbonyl group, aminocarbonyl group, aminosulfonyl group, sulfinyl group, and sulfonyl group, which may have a substituent. [3] The reversible thermochromic composition according to [2], wherein in the formula (1), at least one A or A' is an electron-withdrawing group selected from a fluoro group, an alkyl group having at least one fluoro group, and an oxycarbonyl group, which may have a substituent. [4] The reversible thermochromic composition according to [1], wherein in formula (1), at least one A or A' is a hydrogen-bonding group selected from a carboxyl group, an amino group which may have a substituent, a carbonylamino group, a urea group, and a sulfonylamido group. [5] The reversible thermochromic composition according to any one of [1] to [4], wherein in formula (1), at least one A or A' is bonded to the * position in formula (1). [6] The reversible thermochromic composition according to [4] or [5], wherein in formula (1), a is 1 or more, at least one A is bonded to the * position in formula (1), the A bonded to the * position is a hydrogen-bonding group selected from a carboxyl group, an amino group which may have a substituent, a carbonylamino group, a urea group, and a sulfonylamido group, and b is 0. [7] The reversible thermochromic composition according to any one of [1] to [5], wherein in formula (1), b is 1. [8] A microcapsule pigment in which the reversible thermochromic composition according to any one of [1] to [7] is encapsulated in microcapsules. [9] A writing instrument containing the reversible thermochromic composition according to any one of [1] to [7] or the microcapsule pigment according to [8].

[10] A toy containing the reversible thermochromic composition according to any one of [1] to [7] or the microcapsule pigment according to [8].

[0009] According to the present invention, there are provided a reversible thermochromic composition having excellent color development sensitivity and decolorization properties, a writing instrument containing the reversible thermochromic composition, and a toy containing the reversible thermochromic composition.

[0010] The present invention will be described in detail below, but the present invention is not limited to the following description and can be modified as desired without departing from the gist of the present invention. In the present invention, when an expression using "~" is used with a numerical value or physical property value before and after it, the value before and after it is included in the expression.

[0011] A reversible thermochromic composition according to one embodiment of the present invention comprises a color developer containing a compound represented by the following formula (1), a leuco dye, and a color change temperature regulator. In this specification, the compound represented by formula (1) may be referred to as "compound (1)." (In the above formula (1), a, a', b, A, A', and X are as follows: a is an integer selected from 0 to 5; a' is an integer selected from 0 to 5; b is 0 or 1; X is -C(=Y)- or -SO ２ -, the sum of a and a' is 1 or more, A and A' are each independently an electron-withdrawing group or a hydrogen-bonding group, and Y is O or S. However, the benzene ring in the above formula (1) may have a substituent other than A or A'.

[0012] The reversible thermochromic composition according to an embodiment of the present invention exhibits remarkable effects, such as excellent color development sensitivity and decolorization upon application of heat. The reason why the reversible thermochromic composition exhibits such excellent effects is presumably due to the following reasons. That is, in the formula (1), the composition contains A and / or A', and at least one of A or A' is an electron-withdrawing group or a hydrogen-bonding group. This moderately reduces crystallinity, improving reactivity and compatibility with the leuco dye, thereby increasing color development sensitivity. Furthermore, improved compatibility with the color change temperature regulator is also thought to improve decolorization.

[0013] [Color Developer] The color developer contained in the reversible thermochromic composition according to this embodiment contains a compound represented by the above formula (1). In the above formula (1), a is an integer selected from 0 to 5, preferably 4 or less, and more preferably 3 or less. It is believed that when a is large, the molecules become less mobile, resulting in a decrease in color-developing sensitivity and decolorization ability. In the above formula (1), a' is an integer selected from 0 to 5, preferably 4 or less, and more preferably 3 or less. It is believed that when a' is large, the molecules become less mobile, resulting in a decrease in color-developing sensitivity and decolorization ability. However, the sum of a and a' is 1 or more. When the sum of a and a' is 1 or more, crystallinity is appropriately reduced, improving reactivity and compatibility with the leuco dye, thereby increasing color-developing sensitivity, while improving compatibility with the color-changing agent temperature regulator, thereby improving decolorization ability.

[0014] In the above formula (1), b is 0 or 1, preferably 1. When b is 1, the number of proton-donating hydrogen atoms that contribute to the color development of the leuco formula increases, thereby increasing the reactivity with the leuco dye and improving the color development sensitivity and the preservation of the color development state in a temperature range lower than the decolorization temperature. When b is 0, a is preferably 1 or more. It is believed that when a is 1 or more, the reactivity with the leuco dye is increased.

[0015] X is -C(=Y)- or -SO ２ -, and Y is O or S. These can be appropriately selected to obtain a developer exhibiting the desired color development sensitivity and decolorization property. -C(=Y)- is preferred because it has high compatibility with the leuco dye, while -SO ２ Y is preferably O because of its excellent reactivity with the leuco dye, and S because of its particularly excellent compatibility with the leuco dye.

[0016] In this specification, the electron-withdrawing group refers to a substituent having electron-withdrawing properties. The electron-withdrawing group in this specification refers to a substituent having a Hammett's substituent constant (para position, σp) greater than 0. Hammett's substituent constants are described, for example, in "Graduate School Lectures on Organic Chemistry," edited by Noyori Ryoji et al., 1st Edition, Vol. I, Tokyo Kagaku Dojin Co., Ltd., June 1999, p. 175. Examples of electron-withdrawing groups include, but are not limited to, halogen atoms, nitrile groups, carboxyl groups, alkyl groups having at least one fluoro group, and optionally substituted oxycarbonyl groups, carbonyl groups, aminocarbonyl groups, aminosulfonyl groups, sulfinyl groups, and sulfonyl groups.

[0017] In this specification, the term "hydrogen-bonding group" refers to a substituent having an active proton site or a site capable of donating a hydrogen bond. Examples of the hydrogen-bonding group include, but are not limited to, a carboxyl group, an optionally substituted amino group, a carbonylamino group, a urea group, or a sulfonylamido group.

[0018] The benzene ring in the above formula (1) may have a substituent other than A or A'. Examples of the substituent other than A or A' that may be had include, but are not limited to, an alkyl group, an aryl group, a heteroaryl group, an ether group, a thioether group, a carbonyloxy group, or a sulfonyloxy group that may have a substituent.

[0019] Examples of the halogen atom include a fluoro group, a chloro group, a bromo group, and an iodo group. A fluoro group, a chloro group, or a bromo group is preferred because it has a high reactivity with the leuco dye. A fluoro group or a chloro group is particularly preferred because it tends to have high light resistance, and a fluoro group is more preferred.

[0020] The alkyl group is preferably a linear or branched alkyl group having 1 to 22 carbon atoms, which may have a substituent. The alkyl group enhances compatibility with the discoloration temperature regulator and can improve decolorization properties. If the number of carbon atoms is too large, the melting point will be too low, which may reduce the preservability of the colored state or reduce the color development properties. Therefore, the number of carbon atoms is preferably 12 or less, more preferably 6 or less, and particularly preferably 4 or less.

[0021] Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a t-butyl group, a pentyl group, a hexyl group, a heptyl group, a 1-ethylpentyl group, an octyl group, a 2-ethylhexyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group, a nonadecyl group, an icosyl group, an eicosyl group, a heniicosyl group, and a docosyl group. Preferably, it is a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a t-butyl group, a pentyl group, or a hexyl group, more preferably a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, or a t-butyl group, and particularly preferably a methyl group.

[0022] The alkyl group may have a substituent, and a halogen atom is preferred as the substituent because the electron-withdrawing property enhances the reactivity with the leuco dye. Among these, a fluoro group, a chloro group, or a bromo group is preferred, and a fluoro group is particularly preferred.

[0023] In the above formula (1), it is particularly preferable that A and / or A' are alkyl groups having at least one fluoro group. When A and / or A' have at least one fluoro group, the color-developing sensitivity can be increased due to its electron-withdrawing property. There are no restrictions on the position or number of the fluoro groups, but a large number of fluoro groups increases the electron-withdrawing property and the reactivity with the leuco dye, so a perfluoroalkyl group is preferred. On the other hand, if the number of fluoro groups is too large, it is thought that the compatibility with the leuco dye and the discoloration temperature regulator will decrease, resulting in a decrease in color-developing sensitivity and decolorization ability. A trifluoromethyl group is particularly preferable because its strong electron-withdrawing property increases the reactivity with the leuco dye and provides appropriate compatibility.

[0024] The aryl group and heteroaryl group are, respectively, aromatic hydrocarbon groups having 6 to 20 carbon atoms, which may have a substituent, or aromatic heterocyclic groups having 2 to 20 carbon atoms, which may have a substituent. Examples of aromatic hydrocarbon groups include phenyl groups, naphthyl groups, phenanthryl groups, biphenyl groups, anthryl groups, pyrenyl groups, fluorenyl groups, azulenyl groups, acenaphthenyl groups, fluoranthenyl groups, naphthacenyl groups, perylenyl groups, pentacenyl groups, triphenylenyl groups, and quaterphenyl groups. Among these, phenyl groups and naphthyl groups are preferred.

[0025] Examples of aromatic heterocyclic groups include pyridyl, thienyl, furyl, pyrrolyl, oxazolyl, thiazolyl, oxadiazolyl, thiadiazolyl, pyrazinyl, pyrimidinyl, pyrazolyl, imidazolyl, benzothienyl, dibenzofuryl, dibenzothienyl, phenylcarbazolyl, phenoxathienyl, xanthenyl, benzofuranyl, thianthrenyl, indolizinyl, phenoxazinyl, phenothiazinyl, acridinyl, phenanthridinyl, phenanthrolinyl, quinolyl, isoquinolyl, indolyl, and quinoxalinyl. Among these, a pyridyl group, a pyrazinyl group, a pyrimidinyl group, a pyrazolyl group, a quinolyl group, an isoquinolyl group, an imidazolyl group, an acridinyl group, a phenanthridinyl group, a phenanthrolinyl group, a quinoxalinyl group, a dibenzofuryl group, a dibenzothienyl group, a phenylcarbazolyl group, a xanthenyl group, and a phenoxazinyl group are preferred.

[0026] Among the aryl groups and heteroaryl groups, aromatic hydrocarbon groups are preferred, and phenyl groups are particularly preferred, since they can improve compatibility with leuco dyes and discoloration temperature regulators, thereby easily increasing color development sensitivity and decolorization properties.

[0027] The ether group is represented by the following formula (2).

[0028] In the above formula (2), R １ is an alkyl group having 1 to 12 carbon atoms, an aromatic hydrocarbon group having 6 to 14 carbon atoms, or an aromatic heterocyclic group having 2 to 10 carbon atoms, which may have an optional substituent. An alkyl group is preferred because it can reduce crystallinity, thereby increasing compatibility with the discoloration temperature regulator and improving the decolorization property, and an aromatic hydrocarbon group is preferred because it increases compatibility with the discoloration temperature regulator and improves the decolorization property. In formula (2), * is the site that bonds to A.

[0029] Examples of alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl, undecyl, and dodecyl. If the chain length is too long, compatibility with the color change temperature regulator becomes too high, and the stability of the colored state tends to decrease. Therefore, preferred are methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, nonyl, and decyl groups.

[0030] Examples of aromatic hydrocarbon groups include phenyl, naphthyl, phenanthryl, biphenyl, anthryl, pyrenyl, fluorenyl, azulenyl, acenaphthenyl, fluoranthenyl, naphthacenyl, perylenyl, pentacenyl, triphenylenyl, and quaterphenyl groups. Among these, phenyl and naphthyl groups are preferred.

[0031] Examples of aromatic heterocyclic groups include pyridyl, thienyl, furyl, pyrrolyl, oxazolyl, thiazolyl, oxadiazolyl, thiadiazolyl, pyrazinyl, pyrimidinyl, pyrazolyl, imidazolyl, benzothienyl, dibenzofuryl, dibenzothienyl, phenylcarbazolyl, phenoxathienyl, xanthenyl, benzofuranyl, thianthrenyl, indolizinyl, phenoxazinyl, phenothiazinyl, acridinyl, phenanthridinyl, phenanthrolinyl, quinolyl, isoquinolyl, indolyl, and quinoxalinyl. Among these, a pyridyl group, a pyrazinyl group, a pyrimidinyl group, a pyrazolyl group, a quinolyl group, an isoquinolyl group, an imidazolyl group, an acridinyl group, a phenanthridinyl group, a phenanthrolinyl group, a quinoxalinyl group, a dibenzofuryl group, a dibenzothienyl group, a phenylcarbazolyl group, a xanthenyl group, or a phenoxazinyl group is preferred.

[0032] The thioether group is represented by the following formula (3).

[0033] In the above formula (3), R ２ is R １ The same applies as above. An alkyl group is preferred because it can reduce crystallinity, thereby increasing compatibility with the discoloration temperature regulator and improving the decolorization property, and an aromatic hydrocarbon group or aromatic heterocyclic group is preferred because it increases compatibility with the discoloration temperature regulator and improves the decolorization property. In formula (3), * is the site that bonds to A.

[0034] The oxycarbonyl group is represented by the following formula (4).

[0035] In the above formula (4), R ３ is R １ The same applies as above. An alkyl group is preferred because it can reduce crystallinity, thereby increasing compatibility with the discoloration temperature regulator and improving the decolorization property, and an aromatic hydrocarbon group or aromatic heterocyclic group is preferred because it increases compatibility with the discoloration temperature regulator and improves the decolorization property. When A and / or A' is an oxycarbonyl group, its electron-withdrawing property can increase the reactivity with the leuco dye, and at the same time, it can improve compatibility with the discoloration temperature regulator and improve the decolorization property. In formula (4), * is the site bonding to A.

[0036] The carbonyloxy group is represented by the following formula (5).

[0037] In the above formula (5), R ４ is R １ The same applies as above. An alkyl group is preferred because it can reduce crystallinity, thereby increasing compatibility with the discoloration temperature regulator and improving the decolorization property, and an aromatic hydrocarbon group or aromatic heterocyclic group is preferred because it increases compatibility with the discoloration temperature regulator and improves the decolorization property. In formula (5), * is the site that bonds to A.

[0038] The carbonyl group is represented by the following formula (6).

[0039] In the above formula (6), R ５ is R １The same applies as above. An alkyl group is preferred because it can reduce crystallinity, thereby increasing compatibility with the discoloration temperature regulator and improving the decolorization property, and an aromatic hydrocarbon group or aromatic heterocyclic group is preferred because it can increase compatibility with the discoloration temperature regulator and improve the decolorization property. When A and / or A' is a carbonyl group, its electron-withdrawing property can increase the reactivity with the leuco dye, and at the same time, it can improve compatibility with the discoloration temperature regulator and improve the decolorization property. In formula (6), * is the site bonding to A.

[0040] The amino group is represented by the following formula (7).

[0041] In the above formula (7), R ６ is R １ The same applies as above. An alkyl group is preferred because it can increase compatibility with the discoloration temperature regulator and improve the erasing property by decreasing the crystallinity, and an aromatic hydrocarbon group or an aromatic heterocyclic group is preferred because it can increase compatibility with the discoloration temperature regulator and improve the erasing property. When A and / or A' are amino groups, the number of hydrogen atoms that contribute to the reaction with the leuco dye increases, making it possible to increase the color development sensitivity and, at the same time, improve compatibility with the discoloration temperature regulator and improve the erasing property. R is particularly preferred because it can increase the proton donating property of A and / or A'. ６ is an aromatic hydrocarbon group or an aromatic heterocyclic group, and among these, an aromatic hydrocarbon group is preferable. In formula (7), * is the site where A is bonded.

[0042] The carbonylamino group is represented by the following formula (8).

[0043] In the above formula (8), R ７ is R １The same applies as above. An alkyl group is preferred because reducing the crystallinity increases compatibility with the color change temperature regulator and improves the erasability, while an aromatic hydrocarbon group or aromatic heterocyclic group is preferred because it increases compatibility with the color change temperature regulator and improves the erasability. When A and / or A' is a carbonylamino group, the number of hydrogen atoms that contribute to the reaction with the leuco dye increases, thereby increasing the color development sensitivity and improving compatibility with the color change temperature regulator and the erasability. In formula (8), * represents the site that bonds to A.

[0044] The aminocarbonyl group is represented by the following formula (9).

[0045] In the above formula (9), R ８ is R １ The same applies as above. An alkyl group is preferred because it can reduce crystallinity, thereby increasing compatibility with the discoloration temperature regulator and improving the decolorization property, and an aromatic hydrocarbon group or aromatic heterocyclic group is preferred because it increases compatibility with the discoloration temperature regulator and improves the decolorization property. When A and / or A' is an aminocarbonyl group, its electron-withdrawing property can increase the reactivity with the leuco dye, and at the same time, it can improve compatibility with the discoloration temperature regulator and improve the decolorization property. In formula (9), * is the site bonding to A.

[0046] The urea group is represented by the following formula (10).

[0047] In the above formula (10), R ９ is R １ The same applies as above. An alkyl group is preferred because decreasing the crystallinity increases compatibility with the color change temperature regulator and improves the erasability, and an aromatic hydrocarbon group or aromatic heterocyclic group is preferred because it increases compatibility with the color change temperature regulator and improves the erasability. When A and / or A' is a urea group, the number of hydrogen atoms that contribute to the reaction with the leuco dye increases, thereby increasing the color development sensitivity and improving compatibility with the color change temperature regulator and the erasability. In formula (10), * represents the site that bonds to A.

[0048] The sulfonylamido group is represented by the following formula (11).

[0049] In the above formula (11), R １０ is R １ The same applies as above. An alkyl group is preferred because decreasing the crystallinity increases compatibility with the color change temperature regulator and improves the erasing property, and an aromatic hydrocarbon group or aromatic heterocyclic group is preferred because it increases compatibility with the color change temperature regulator and improves the erasing property. When A and / or A' is a sulfonylamide group, the number of hydrogen atoms that contribute to the reaction with the leuco dye increases, thereby increasing the color development sensitivity and improving compatibility with the color change temperature regulator and the erasing property. In formula (11), * represents the site that bonds to A.

[0050] The aminosulfonyl group is represented by the following formula (12).

[0051] In the above formula (12), R １１ is R １ The same applies as above. An alkyl group is preferred because it can reduce crystallinity, thereby increasing compatibility with the discoloration temperature regulator and improving the decolorization property, and an aromatic hydrocarbon group or aromatic heterocyclic group is preferred because it can increase compatibility with the discoloration temperature regulator and improve the decolorization property. When A and / or A' is an aminosulfonyl group, its electron-withdrawing property can increase the reactivity with the leuco dye, and at the same time, it can improve compatibility with the discoloration temperature regulator and improve the decolorization property. In formula (12), * represents the site binding to A.

[0052] The sulfinyl group is represented by the following formula (13).

[0053] In the above formula (13), R １２ is R １The same applies as above. An alkyl group is preferred because it can reduce crystallinity, thereby increasing compatibility with the discoloration temperature regulator and improving the decolorization property, and an aromatic hydrocarbon group or aromatic heterocyclic group is preferred because it can increase compatibility with the discoloration temperature regulator and improve the decolorization property. When A and / or A' is a sulfinyl group, its electron-withdrawing property can increase the reactivity with the leuco dye, and at the same time, it can improve compatibility with the discoloration temperature regulator and improve the decolorization property. In formula (13), * represents the site bonding to A.

[0054] The sulfonyl group is represented by the following formula (14).

[0055] In the above formula (14), R １３ is R １ The same applies as above. An alkyl group is preferred because it can reduce crystallinity, thereby increasing compatibility with the discoloration temperature regulator and improving the decolorization property, and an aromatic hydrocarbon group or aromatic heterocyclic group is preferred because it can increase compatibility with the discoloration temperature regulator and improve the decolorization property. When A and / or A' is a sulfonyl group, its electron-withdrawing property can increase the reactivity with the leuco dye, and at the same time, it can improve compatibility with the discoloration temperature regulator and improve the decolorization property. In formula (14), * is the site bonding to A.

[0056] The sulfonyloxy group is represented by the following formula (15).

[0057] In the above formula (15), R １４ is R １ The same applies as above. An alkyl group is preferred because it can reduce crystallinity, thereby increasing compatibility with the discoloration temperature regulator and improving the decolorization property, and an aromatic hydrocarbon group or aromatic heterocyclic group is preferred because it increases compatibility with the discoloration temperature regulator and improves the decolorization property. In formula (15), * is the site that bonds to A.

[0058] In the above formula (1), when A and A′ are substituents selected from an alkyl group, an aryl group, a heteroaryl group, an ether group, a thioether group, an oxycarbonyl group, a carbonyloxy group, a carbonyl group, an amino group, a carbonylamino group, an aminocarbonyl group, a urea group, a sulfonylamido group, an aminosulfonyl group, a sulfinyl group, a sulfonyl group, and a sulfonyloxy group, they may further have any optional substituent.

[0059] In the above formula (1), it is preferred that at least one of A or A' is an electron-withdrawing group selected from a fluoro group, an alkyl group having at least one fluoro group, and an oxycarbonyl group which may have a substituent, or a hydrogen-bonding group selected from a carboxyl group, a carbonylamino group, a urea group, and a sulfonylamido group. When at least one of A or A' is an electron-withdrawing or hydrogen-bonding substituent, the reactivity with the leuco dye is enhanced, which facilitates improvement of color-developing sensitivity and improves compatibility with the color-change temperature regulator. In particular, a fluoro group or an alkyl group having at least one fluoro group is preferred because it is easy to achieve both improved reactivity with the leuco dye due to its strong electron-withdrawing property and improved compatibility with the leuco dye, and a trifluoromethyl group is particularly preferred.

[0060] In the above formula (1), it is preferable that at least one A or A' is bonded to the * position described in formula (1). It is believed that the presence of a substituent at this position, which is adjacent to the NH group involved in the reaction with the leuco dye, moderately reduces the stability of the colored state resulting from the reaction with the leuco dye due to steric hindrance and electronic repulsion, thereby effectively improving the decolorization property when heat is applied.

[0061] In the above formula (1), it is preferable that at least one A or A' bonded to the * position is a hydrogen-bonding group. The hydrogen-bonding group bonded to the * position facilitates intramolecular hydrogen bonding with adjacent NH groups, weakening intermolecular hydrogen bonds, thereby suppressing crystallinity, preventing the melting point from becoming too high, and improving compatibility with the leuco dye. At the same time, it is also thought that the hydrogen-bonding group can participate in the reaction with the leuco dye, thereby effectively improving color-developing sensitivity.

[0062] In the above formula (1), when b is 0, it is preferable that at least one A or A' is a hydrogen-bonding group bonded to the * position described in formula (1). It is more preferable that a is 1 or more, at least one A is bonded to the * position described in formula (1), and the A bonded to the * position is a hydrogen-bonding group.

[0063] Specific examples of the above formula (1) include, but are not limited to, the following:

[0064] The compound of formula (1) above can be synthesized by known methods (for example, Japanese Patent Nos. 2679459, 4601174, 5887423, and the literature (Journal of American Chemical Society 2016, Vol. 138 (No. 40), pp. 13314-13325), and the literature (Org. Lett., 2016, 18, 3726-3729)).

[0065] [Leuco Dye] The reversible thermochromic composition according to an embodiment of the present invention contains a leuco dye. Leuco dyes are typically basic, and any known leuco dyes can be used. Specific examples of leuco dyes include conventionally known diphenylmethane phthalides, phenylindolyl phthalides, indolyl phthalides, diphenylmethane azaphthalides, phenylindolyl azaphthalides, fluorans, styrinoquinolines, and diazarhodamine lactones. These leuco dyes (leuco dye precursors) may be used alone or in combination of two or more. Furthermore, the developer is preferably used in an amount of 0.1 to 50 parts by weight, more preferably 0.5 to 20 parts by weight, per part by weight of the leuco dye.

[0066] Specific examples of leuco dyes include 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide, 3-(4-diethylaminophenyl)-3-(1-ethyl-2-methylindol-3-yl)phthalide, 3,3-bis(1-n-butyl-2-methylindol-3-yl)phthalide, 3,3-bis(2-ethoxy-4-diethylaminophenyl)-4-azaphthalide, 3-[2-ethoxy-4-(N-ethylanilino)phenyl]-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide, 3,6-diphenyl fluoran, 3,6-dimethoxyfluoran, 3,6-di-n-butoxyfluoran, 2-methyl-6-(N-ethyl-N-p-tolylamino)fluoran, 3-chloro-6-cyclohexylaminofluoran, 2-methyl-6-cyclohexylaminofluoran, 2-(2-chloroanilino)-6-di-n-butylaminofluoran, 2-(3-trifluoromethylanilino)-6-diethylaminofluoran, 2-(N-methylanilino)-6-(N-ethyl-N-p-tolylamino)fluoran, 1 , 3-dimethyl-6-diethylaminofluoran, 2-chloro-3-methyl-6-diethylaminofluoran, 2-anilino-3-methyl-6-diethylaminofluoran, 2-anilino-3-methyl-6-di-n-butylaminofluoran, 2-xylidino-3-methyl-6-diethylaminofluoran, 1,2-benz-6-diethylaminofluoran, 1,2-benz-6-(N-ethyl-N-isobutylamino)fluoran, 1,2-benz-6-(N-ethyl-N-isoamylamino)fluoran, 2 -(3-methoxy-4-dodecoxystyryl)quinoline, 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-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-(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-N-i-amylamino)-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-phenyl-spiro[5H-(1)benzopyrano Examples of suitable compounds include (2,3-d)pyrimidin-5,1'(3'H)isobenzofuran)-3'-one, 3-(2-methoxy-4-dimethylaminophenyl)-3-(1-butyl-2-methylindol-3-yl)-4,5,6,7-tetrachlorophthalide, 3-(2-ethoxy-4-diethylaminophenyl)-3-(1-ethyl-2-methylindol-3-yl)-4,5,6,7-tetrachlorophthalide, and 3-(2-ethoxy-4-diethylaminophenyl)-3-(1-pentyl-2-methylindol-3-yl)-4,5,6,7-tetrachlorophthalide. Further examples include pyridine-based, quinazoline-based, and bisquinazoline-based compounds, which are effective in producing fluorescent yellow to red colors.

[0067] [Color Change Temperature Regulator] The reversible thermochromic composition of this embodiment contains a color change temperature regulator. The color change temperature regulator is a substance that reversibly induces an electron donor / acceptor reaction between the developer and the leuco dye. Known color change temperature regulators can be used, and specific examples include chain hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, alcohols, esters, ketones, ethers, and acid amides. Of these, those having 8 or more carbon atoms are preferred, and those having 10 or more carbon atoms are more preferred. Furthermore, those having 30 or less carbon atoms are preferred.

[0068] Specific examples of the ester include compounds represented by the following formulas (16) to (19) (hereinafter, sometimes referred to as compounds (16) to (19)). (In formula (16), X １are independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a methoxy group, or a halogen atom, m is independently an integer of 1 to 3, and n is an integer of 1 to 8.

[0069] Examples of compound (16) include a diester of malonic acid and 2-[4-(4-chlorobenzyloxy)phenyl)]ethanol, a diester of succinic acid and 2-(4-benzyloxyphenyl)ethanol, a diester of succinic acid and 2-[4-(3-methylbenzyloxy)phenyl)]ethanol, a diester of glutaric acid and 2-(4-benzyloxyphenyl)ethanol, a diester of glutaric acid and 2-[4-(4-chlorobenzyloxy)phenyl)]ethanol, a diester of adipic acid and 2-(4-benzyloxyphenyl)ethanol, a diester of pimelic acid and 2-(4-benzyloxyphenyl)ethanol, a diester of suberic acid and 2-(4-benzyloxyphenyl)ethanol, a diester of suberic acid and 2-[4-(3-methylbenzyloxy)phenyl]ethanol, Examples thereof include a diester of suberic acid and 2-[4-(4-chlorobenzyloxy)phenyl)]ethanol, a diester of suberic acid and 2-[4-(2,4-dichlorobenzyloxy)phenyl)]ethanol, a diester of azelaic acid and 2-(4-benzyloxyphenyl)ethanol, a diester of sebacic acid and 2-(4-benzyloxyphenyl)ethanol, a diester of 1,10-decanedicarboxylic acid and 2-(4-benzyloxyphenyl)ethanol, a diester of 1,18-octadecanedicarboxylic acid and 2-(4-benzyloxyphenyl)ethanol, and a diester of 1,18-octadecanedicarboxylic acid and 2-[4-(2-methylbenzyloxy)phenyl)]ethanol.

[0070] (In formula (17), R １５ is a hydrogen atom or a methyl group, r is an integer of 0 to 2, and X ２ , X ３ Either one of them is -(CH ２ ) ｎ OCOR １６ or -(CH ２ ) ｎ COOR１６ the other is a hydrogen atom, n is an integer of 0 to 2, and R １６ is an alkyl or alkenyl group having 4 or more carbon atoms, and Y ２ and Y ３ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a methoxy group, or a halogen atom, and p and q are each independently an integer of 1 to 3.

[0071] In the formula (17), R １５ is a hydrogen atom, it is preferable because a reversible thermochromic composition having a wider hysteresis width can be obtained, and R １５ It is more preferable that is a hydrogen atom and m is 0.

[0072] Among the compounds (17), the compound represented by the following formula (18) is more preferred. (In formula (18), R １６ is an alkyl or alkenyl group having 7 or more carbon atoms, preferably an alkyl group having 9 to 24 carbon atoms, and more preferably an alkyl group having 9 to 20 carbon atoms.

[0073] Examples of compound (18) include 4-benzyloxyphenylethyl octanoate, 4-benzyloxyphenylethyl nonanoate, 4-benzyloxyphenylethyl decanoate, 4-benzyloxyphenylethyl undecanoate, 4-benzyloxyphenylethyl dodecanoate, 4-benzyloxyphenylethyl tridecanoate, 4-benzyloxyphenylethyl tetradecanoate, 4-benzyloxyphenylethyl pentadecanoate, 4-benzyloxyphenylethyl hexadecanoate, 4-benzyloxyphenylethyl heptadecanoate, and 4-benzyloxyphenylethyl octadecanoate.

[0074] (In formula (19), R １７ is an alkyl or alkenyl group having 7 or more carbon atoms, s and t are each independently an integer of 1 to 3, and X ４ and Y ４ are each independently 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.

[0075] Examples of compound (19) include 1,1-diphenylmethyl octanoate, 1,1-diphenylmethyl nonanoate, 1,1-diphenylmethyl decanoate, 1,1-diphenylmethyl undecanoate, 1,1-diphenylmethyl dodecanoate, 1,1-diphenylmethyl tridecanoate, 1,1-diphenylmethyl tetradecanoate, 1,1-diphenylmethyl pentadecanoate, 1,1-diphenylmethyl hexadecanoate, 1,1-diphenylmethyl heptadecanoate, and 1,1-diphenylmethyl octadecanoate. These discoloration temperature regulators may be used alone or in combination of two or more.

[0076] The discoloration temperature regulator is preferably used in an amount of 1 to 800 parts by weight, more preferably 5 to 200 parts by weight, per part by weight of the leuco dye.

[0077] By heating to a temperature exceeding the melting point of the discoloration temperature regulator, the colored state caused by the electron donor / acceptor reaction between the leuco dye and the developer can be changed to a discolored state.

[0078] [Other Additives] The reversible thermochromic composition according to this embodiment may contain a color developer other than compound (1) (hereinafter, may be referred to as "other color developers"), a sensitizer, a stabilizer, a crosslinking agent, a pigment, a lubricant, etc.

[0079] <Other Color Developers> The reversible thermochromic composition may contain other color developers to the extent that the effects of the present invention are not impaired. Any known other color developers can be used as the other color developers, and although there are no particular limitations, an electron-accepting color developer is preferred. One type of other color developer may be used alone, or two or more types may be used in combination. When using other color developers, the amount used is preferably 1 to 5,000 parts by weight, more preferably 5 to 1,000 parts by weight, and even more preferably 10 to 500 parts by weight, relative to 100 parts by weight of the color developer containing the compound represented by formula (1). By using other color developers, a reversible thermochromic composition can be obtained that maintains high color development sensitivity and has improved decolorization properties.

[0080] Other color developers include monophenols and polyphenols, which may further have, as substituents, alkyl groups, aryl groups, acyl groups, alkoxycarbonyl groups, carboxy groups and their esters, amide groups, halogen groups, etc. Other examples include bis- or tris-phenols, phenol-aldehyde condensation resins, etc. Furthermore, metal salts of compounds having a phenolic hydroxyl group may also be used.

[0081] Specific examples are listed below: phenol, o-cresol, t-butylcatechol, nonylphenol, n-octylphenol, n-dodecylphenol, n-stearylphenol, p-chlorophenol, p-bromophenol, o-phenylphenol, n-butyl p-hydroxybenzoate, n-octyl p-hydroxybenzoate, resorcinol, dodecyl gallate, 2,2-bis(4'-hydroxyphenyl)propane, 4,4-dihydroxydiphenyl sulfone, 1,1-bis(4'-hydroxyphenyl)ethane, 2,2-bis(4'-hydroxy-3-methylphenyl)propane, bis(4-hydroxyphenyl)sulfide, 1-phenyl-1,1-bis(4'-hydroxyphenyl)ethane, 1,1-bis(4'-hydroxyphenyl)-3-methylbutane, 1,1-bis(4'-hydroxyphenyl)-2 ... 2,2-bis(4'-hydroxyphenyl)-2-methylpropane, 1,1-bis(4'-hydroxyphenyl)n-hexane, 1,1-bis(4'-hydroxyphenyl)n-heptane, 1,1-bis(4'-hydroxyphenyl)n-octane, 1,1-bis(4'-hydroxyphenyl)n-nonane, 1,1-bis(4'-hydroxyphenyl)n-decane, 1,1-bis(4'-hydroxyphenyl)n-dodecane, 2,2-bis(4'-hydroxyphenyl)butane, 2,2-bis(4'-hydroxyphenyl)ethyl propionate, 2,2-bis(4'-hydroxyphenyl)-4-methylpentane, 2,2-bis(4'-hydroxyphenyl)hexafluoropropane, 2,2-bis(4'-hydroxyphenyl)n-heptane, 2,2-bis(4'-hydroxyphenyl)n-nonane, and the like.

[0082] In addition, when a compound having a phenolic hydroxyl group that has at least three or more benzene rings and a molecular weight of 250 or more, preferably a molecular weight of 250 or more and 500 or less, or a compound having a phenolic hydroxyl group represented by the following formula (20) is used as the compound having a phenolic hydroxyl group, the degree of color change between color-developed states can be made more acute. (In formula (20), R １８ is an alkyl group having 1 to 8 carbon atoms.

[0083] Examples of the compound having at least three benzene rings and a phenolic hydroxyl group with a molecular weight of 250 or more include 4,4',4"-methylidene trisphenol, 2,6-bis[(2-hydroxy-5-methylphenol)methyl]-4-methylphenol, 4,4'-[1-[4-[1-(4-hydroxyphenyl)-1-methylethyl]phenyl]ethylidene]bisphenol, 4,4',4"-ethylidene tris[2-methylphenol], 4,4'-[(2-hydroxyphenyl)methylene]bis[2,3,6-triphenyl 4-hydroxyphenylmethylene]bis[2-methylphenol], 2,2-methylenebis[6-[(2-hydroxy-5-methylphenyl)methyl]-4-methylphenol], 2,4,6-tris(4-hydroxyphenylmethyl)1,3-benzenediol, 4,4',4"-ethylidenetrisphenol, 4,4'-[(4-hydroxyphenyl)methylene]bis[2-methylphenol], 4,4'-[(4-hydroxyphenyl)methylene]bis[2,6-dimethylphenol], 4,4'-[(4-hydroxy-3-methoxyphenyl)methylene]bis[2,6-dimethylphenol] phenol], 2,4-bis[(5-methyl-2-hydroxyphenyl)methyl]-6-cyclohexylphenol, 4,4'-[1-[4-[1-(4-hydroxy-3-methylphenol)-1-methylethyl]phenyl]ethylidene]bis[2-methylphenol], 4,4'-[(4-hydroxyphenyl)methylene]bis[2-cyclohexyl-5-methylphenol], 4,6-bis[(4-hydroxyphenyl)methyl]1,3-benzenediol, 4,4'-[(3,4-dihydroxyphenyl)methylene]bis[2,6 -dimethylphenol], 4,4'-(1-phenylethylidene)bisphenol, 5,5'-(1-methylethylidene)bis[1-phenyl-2-ol], 4,4'-[1-[4-[1-(4-hydroxyphenyl)-1-methylethyl]phenyl]ethylidene]bisphenol, 4,4'-(phenylmethylene)bisphenol, 4,4'-[1,4-phenylenebis(1-methylethylidene)]bis[2-methylphenol], 5,5'-(1,1-cyclohexylidene)bis-[1-biphenyl-2-ol], and the like.

[0084] Examples of the compound having a phenolic hydroxyl group represented by the formula (20) include bis(3-methyl-4-hydroxyphenyl)sulfide, bis(3,5-dimethyl-4-hydroxyphenyl), bis(3-ethyl-4-hydroxyphenyl)sulfide, bis(3,5-diethyl-4-hydroxyphenyl)sulfide, bis(3-propyl-4-hydroxyphenyl)sulfide, bis(3,5-dipropyl-4-hydroxyphenyl)sulfide, bis(3-t-butyl-4-hydroxyphenyl)sulfide, bis(3,5-t-butyl-4-hydroxyphenyl)sulfide, bis(3-pentyl-4-hydroxyphenyl)sulfide, bis(3-hexyl-4-hydroxyphenyl)sulfide, bis(3-heptyl-4-hydroxyphenyl)sulfide, and bis(5-octyl-2-hydroxyphenyl)sulfide.

[0085] The compound having a phenolic hydroxyl group is capable of exhibiting the most effective thermochromic properties, but other color developers may also be compounds selected from aromatic carboxylic acids and aliphatic carboxylic acids having 2 to 5 carbon atoms, carboxylic acid metal salts, acidic phosphate esters and their metal salts, 1,2,3-triazole and its derivatives, and the like.

[0086] The reversible thermochromic composition according to the embodiment of the present invention may be encapsulated in microcapsules to form a microencapsulated pigment. When encapsulated in microcapsules, its functionality is not impaired even when it comes into contact with chemically active substances such as acidic substances, basic substances, and peroxides, or other solvent components. Furthermore, heat resistance stability can be maintained, and the composition of the reversible thermochromic composition remains the same under various usage conditions, thereby achieving the same effects.

[0087] The specific embodiment of the microcapsule pigment is not particularly limited, and reference can be made to, for example, Japanese Patent No. 6851787. Specifically, the microcapsule pigment can be produced by known methods such as interfacial polymerization, in situ polymerization, liquid curing coating, phase separation from an aqueous solution, phase separation from an organic solvent, melt-dispersion cooling, air suspension coating, and spray drying.

[0088] The average particle size of the microcapsule pigment is preferably 0.1 to 100 μm, and more preferably 3 to 30 μm. The particle size and particle size distribution are measured using a laser diffraction / scattering particle size distribution measuring device (LA-300, manufactured by Horiba, Ltd.), and the average particle size (median size) can be calculated on a volume basis based on the measured values.

[0089] The ratio of the inclusions to the wall film constituting the microcapsule pigment is preferably in the range of 7:1 to 1:1 (mass ratio) of inclusions:wall film. By being within this range, it is possible to prevent a decrease in color density and clarity during color development. More preferably, the ratio of the inclusions to the wall film is 6:1 to 1:1 (mass ratio) of inclusions:wall film.

[0090] The reversible thermochromic composition and microcapsule pigment according to the embodiments of the present invention can be used, for example, in printing inks, writing inks, paints, etc. Specifically, a reversible thermochromic layer can be formed on any support or dispersed in a support by printing means such as screen printing, offset printing, gravure printing, coater printing, pad printing, or transfer printing, or by coating means such as brush coating, spray coating, electrostatic coating, electrodeposition coating, flow coating, roller coating, or dip coating.

[0091] The reversible thermochromic composition or microencapsulated pigment may also be housed in a writing implement. The writing implement comprises a barrel housing the reversible thermochromic composition or microencapsulated pigment, and a pen body for delivering the reversible thermochromic composition or microencapsulated pigment from the barrel. Examples of the pen body include a marking pen body, a ballpoint pen body, and a brush pen body. Examples of the marking pen body include marking tips such as fiber tips, felt tips, and plastic tips. Examples of the ballpoint pen body include a ballpoint pen tip.

[0092] Toys containing the reversible thermochromic composition or microencapsulated pigment may also be used. Specific examples of the toys include dolls or animal-shaped toys, hair for dolls or animal-shaped toys, doll houses and furniture, doll accessories such as clothes, hats, bags, and shoes, accessory toys, stuffed toys, drawing toys, toy picture books, puzzle toys such as jigsaw puzzles, building block toys, block toys, clay toys, fluid toys, tops, kites, musical instrument toys, cooking toys, gun toys, catching toys, background toys, vehicles, toys imitating animals, plants, buildings, and food.

[0093] The toy may contain a reversible thermochromic composition or a microencapsulated pigment in any manner, and the reversible thermochromic layer may be formed on the surface of the toy by the printing method, painting method, etc., or the reversible thermochromic composition or the microencapsulated pigment may be dispersed in the material that constitutes the toy. The method of using the toy is not particularly limited, and the reversible thermochromic composition can be caused to change color, for example, by bringing the toy into contact with hot water or cold water.

[0094] The present invention will be described in detail below using examples and comparative examples, but the present invention is not limited to the following examples. In the following examples and comparative examples, "parts" and "%" respectively mean "parts by weight" and "% by weight" unless otherwise specified.

[0095] Synthesis Example 1: Synthesis of 1,3-di(3-(trifluoromethyl)phenyl)urea With reference to a known literature (Journal of American Chemical Society, 2016, Vol. 138 (No. 40), pp. 13314-13325), the target product was obtained by the same procedure as in the synthesis example of 1,3-di-m-tolylurea, except that 3-(trifluoromethyl)phenyl isocyanate (purchased from Tokyo Chemical Industry Co., Ltd.) was used in place of m-tolyl isocyanate in the same molar ratio, and 3-(trifluoromethyl)aniline (purchased from Tokyo Chemical Industry Co., Ltd.) was used in place of m-toluidine in the same molar ratio. The melting point was 201-202 ° C. The chemical shift (δ ppm) in the proton NMR spectrum (400 MHz) measured in deuterated DMSO solvent was as follows: δ: 7.33 (d, 2H), 7.52 (t, 2H), 7.60 (d, 2H), 8.02 (s, 2H), 9.18 (s, 2H)

[0096] Synthesis Example 2: Synthesis of 1-(3-(trifluoromethyl)phenyl)-3-(2-(trifluoromethyl)phenyl)urea With reference to a known literature (Journal of American Chemical Society, 2016, Vol. 138 (No. 40), pp. 13314-13325), the target product was obtained by the same procedure as in the synthesis example of 1,3-di-m-tolylurea, except that 3-(trifluoromethyl)phenyl isocyanate (purchased from Tokyo Chemical Industry Co., Ltd.) was used in place of m-tolyl isocyanate in the same molar ratio, and 2-(trifluoromethyl)aniline (purchased from Tokyo Chemical Industry Co., Ltd.) was used in place of m-toluidine in the same molar ratio. The melting point was 172-173°C. The chemical shift (δ ppm) in the proton NMR spectrum (400 MHz) measured in deuterated DMSO solvent was as follows: δ: 7.32-7.34 (m, 2H), 7.53-7.55 (m, 2H), 7.65-7.71 (m, 2H), 7.92 (d, 1H), 8.03 (s, 1H), 8.17 (s, 1H)

[0097] Synthesis Example 3: Synthesis of 1-(3-(trifluoromethyl)phenyl)-3-(2-carboxyphenyl)urea With reference to a known literature (Journal of American Chemical Society, 2016, Vol. 138 (No. 40), pp. 13314-13325), the target product was obtained by the same procedure as in the synthesis example for 1,3-di-m-tolylurea, except that 3-(trifluoromethyl)phenyl isocyanate (purchased from Tokyo Chemical Industry Co., Ltd.) was used in place of m-tolyl isocyanate in the same molar ratio, and 2-aminobenzoic acid (purchased from Tokyo Chemical Industry Co., Ltd.) was used in place of m-toluidine in the same molar ratio. The melting point was 162°C. The chemical shift (δ ppm) in the proton NMR spectrum (400 MHz) measured in deuterated DMSO solvent was as follows: δ: 7.01-7.05 (m, 1H), 7.28 (d, 1H, J = 7.8Hz), 7.46-7.55 (m, 2H), 7.67 (d, 1H, J = 8.0Hz), 7.93 (d, 1H, J = 7.6Hz), 7.98 (s, 1H), 8.35 (d, 1H, J = 8.8Hz), 10.15 (s, 1H), 10.46 (s, 1H)

[0098] Synthesis Example 4: Synthesis of 1,1'-(1,2-phenylene)bis(3-(3-(trifluoromethyl)phenyl)urea) With reference to a known literature (Journal of American Chemical Society, 2016, Vol. 138 (No. 40), pp. 13314-13325), the target product was obtained by the same procedure as in the synthesis example of 1,3-di-m-tolylurea, except that 3-(trifluoromethyl)phenyl isocyanate (purchased from Tokyo Chemical Industry Co., Ltd.) was used in place of m-tolyl isocyanate in the same molar ratio, and 1,2-diaminobenzene (purchased from Tokyo Chemical Industry Co., Ltd., etc.) was used in place of m-toluidine in a molar ratio of half the equivalent amount. The melting point was 215-216°C. The chemical shift (δ ppm) in the proton NMR spectrum (400 MHz) measured in deuterated DMSO solvent was as follows: δ: 6.27-6.30 (m, 2H), 6.47 (d, 2H), 6.66 (t, 2H), 6.74-6.76 (m, 4H), 7.18 (s, 2H), 7.31 (s, 2H)

[0099] Synthesis Example 5: Synthesis of 4-methyl-N-(2-(3-(trifluoromethyl)phenyl)urea)benzenesulfonamide The target compound was obtained using 1,2-diaminobenzene (available from Tokyo Chemical Industry Co., Ltd., etc.), 3-(trifluoromethyl)phenyl isocyanate (available from Tokyo Chemical Industry Co., Ltd., etc.), and p-toluenesulfonyl chloride (available from Tokyo Chemical Industry Co., Ltd., etc.) as starting materials, in the same manner as in Patent No. 5887423. The chemical shifts (δ ppm) in the proton NMR spectrum (400 MHz) measured in deuterated DMSO solvent were as follows: δ: 2.32 (s, 3H), 6.48 (d, 1H), 6.81 (t, 1H), 7.18 (t, 1H), 7.34 (t, 3H), 7.54-7.59 (m, 4H), 8.00 (d, 2H), 8.31 (s, 1H), 9.51 (s, 1H), 9.88 (s, 1H).

[0100] Synthesis Example 6: Synthesis of N-(2-(3-phenylureido)phenyl)benzenesulfonamide The target compound was obtained using 1,2-diaminobenzene (available from Tokyo Chemical Industry Co., Ltd., etc.), phenyl isocyanate (available from Tokyo Chemical Industry Co., Ltd., etc.), and benzenesulfonyl chloride (available from Tokyo Chemical Industry Co., Ltd., etc.) as starting materials, following the same procedures as in Patent No. 5887423. The chemical shifts (δ ppm) in the proton NMR spectrum (400 MHz) measured in deuterated DMSO solvent were as follows: δ: 6.42 (d, 1H), 6.75 (t, 1H), 6.98 (t, 1H), 7.19 (t, 1H), 7.30 (t, 2H), 7.48 (d, 2H), 7.57 (t, 2H), 7.65 (d, 1H), 7.70 (d, 2H), 8.02 (d, 1H), 8.31 (s, 1H), 9.55 (d, 2H).

[0101] Synthesis Example 7 Synthesis of N,N'-bis(4-fluorophenyl)sulfamide The target compound was obtained by the same procedure as for N,N'-diphenylsulfamide described in the literature (Org. Lett., 2016, 18, 3726-3729) using 4-fluoroaniline (purchased from Tokyo Chemical Industry Co., Ltd.) instead of aniline. The chemical shifts (δ ppm) in the proton NMR spectrum (400 MHz) measured in deuterated chloroform solvent were as follows: δ: 6.66 (brs, 2H), 6.97-7.03 (m, 4H), 7.04-7.08 (m, 4H).

[0102] Synthesis Example 8 Synthesis of N,N'-bis(3-(trifluoromethyl)phenyl)sulfamide The target compound was obtained by the same procedure as for N,N'-diphenylsulfamide described in the literature (Org. Lett., 2016, 18, 3726-3729), except that 3-(trifluoromethyl)aniline (purchased from Tokyo Chemical Industry Co., Ltd.) was used instead of aniline. The chemical shifts (δ ppm) in the proton NMR spectrum (400 MHz) measured in deuterated chloroform solvent were as follows: δ: 7.09 (brs, 2H), 7.26-7.31 (m, 4H), 7.40-7.45 (m, 4H).

[0103] Synthesis Example 9: Synthesis of 1-(3-(trifluoromethyl)phenyl)-3-(4-(methoxycarbonyl)phenyl)urea With reference to a known literature (Journal of American Chemical Society, 2016, Vol. 138 (No. 40), pp. 13314-13325), the target product was obtained by the same procedure as in the synthesis example of 1,3-di-m-tolylurea, except that 3-(trifluoromethyl)phenyl isocyanate (purchased from Tokyo Chemical Industry Co., Ltd.) was used in place of m-tolyl isocyanate in the same molar ratio, and methyl 4-aminobenzoate (purchased from Tokyo Chemical Industry Co., Ltd.) was used in place of m-toluidine in the same molar ratio. The melting point was 182-183°C. The chemical shift (δ ppm) in the proton NMR spectrum (400 MHz) measured in deuterated DMSO solvent was as follows: δ: 3.83 (s, 3H), 7.35 (d, 1H), 7.52 (t, 1H), 7.6-7.65 (m, 3H), 7.91 (d, 2H), 8.03 (s, 1H), 9.17 (s, 1H), 9.22 (s, 1H)

[0104] Synthesis Example 10: Synthesis of 1-(3-(trifluoromethyl)phenyl)-3-(4-(butoxycarbonyl)phenyl)urea With reference to a known literature (Journal of American Chemical Society, 2016, Vol. 138 (No. 40), pp. 13314-13325), the target product was obtained by the same procedure as in the synthesis example of 1,3-di-m-tolylurea, except that 3-(trifluoromethyl)phenyl isocyanate (purchased from Tokyo Chemical Industry Co., Ltd.) was used in place of m-tolyl isocyanate in the same molar ratio, and 4-aminobenzoic acid butyl (purchased from Tokyo Chemical Industry Co., Ltd.) was used in place of m-toluidine in the same molar ratio. The melting point was 167-170°C. The chemical shift (δ ppm) in the proton NMR spectrum (400 MHz) measured in deuterated DMSO solvent was as follows: δ: 0.93 (t, 3H, J = 7.4Hz), 1.35-1.46 (m, 2H), 1.62-1.72 (m, 2H), 4.24 (t, 2H, 6.6Hz), 7.34 (d, 1H, J = 7 .6Hz), 7.53 (t, 1H), 7.57-7.63 (m, 3H), 7.90 (d, 2H, J=8.8Hz), 8.02 (s, 1H), 9.15 (s, 1H), 9.21 (s, 1H)

[0105] Synthesis Example 11: Synthesis of 1-(4-fluorophenyl)-3-(4-(butoxycarbonyl)phenyl)urea With reference to a known literature (Journal of American Chemical Society, 2016, Vol. 138 (No. 40), pp. 13314-13325), the target product was obtained by the same procedure as in the synthesis example of 1,3-di-m-tolylurea, except that 4-fluorophenyl isocyanate (purchased from Tokyo Chemical Industry Co., Ltd.) was used in place of m-tolyl isocyanate in the same molar ratio, and 4-aminobutyl benzoate (purchased from Tokyo Chemical Industry Co., Ltd.) was used in place of m-toluidine in the same molar ratio. The melting point was 146-149°C. The chemical shift (δ ppm) in the proton NMR spectrum (400 MHz) measured in deuterated DMSO solvent was as follows: δ: 0.93 (t, 3H, J = 7.4Hz), 1.35-1.47 (m, 2H), 1.62-1.72 (m, 2H), 4.23 (t, 2H, 6.6Hz), 7.13 (t, 2H, J = 8.8Hz), 7.42-7.50 (m, 2H), 7.58 (d, 2H, J = 8.8Hz), 7.88 (d, 2H, J = 8.8Hz), 8.80 (s, 1H), 9.08 (s, 1H)

[0106] Synthesis Example 12: Synthesis of 1-phenyl-3-(4-(butoxycarbonyl)phenyl)urea With reference to a known literature (Journal of American Chemical Society, 2016, Vol. 138 (No. 40), pp. 13314-13325), the target product was obtained by the same procedure as in the synthesis example of 1,3-di-m-tolylurea, except that phenyl isocyanate (purchased from Tokyo Chemical Industry Co., Ltd.) was used in place of m-tolyl isocyanate in the same molar ratio, and butyl 4-aminobenzoate (purchased from Tokyo Chemical Industry Co., Ltd.) was used in place of m-toluidine in the same molar ratio. The melting point was 120-129°C. The chemical shift (δ ppm) in the proton NMR spectrum (400 MHz) measured in deuterated chloroform solvent was as follows: δ: 0.94 (t, 3H, J=7.4Hz), 1.37-1.47 (m, 2H), 1.65-1.75 (m, 2H), 4.27 (t, 2H, 6.8Hz) , 7.04-7.10 (m, 1H), 7.22-7.29 (m, 4H), 7.33 (d, 2H, J = 8.6Hz), 7.89 (d, 2H, J = 8.6Hz)

[0107] Synthesis Example 13: Synthesis of 1,3-bis(3-(ethoxycarbonyl)phenyl)urea With reference to a known literature (Journal of American Chemical Society, 2016, Vol. 138 (No. 40), pp. 13314-13325), 3-(ethoxycarbonyl)phenyl isocyanate (purchased from Combi-Blocks) was used in place of m-tolyl isocyanate in the same molar ratio, and 3-aminobenzoic acid ethyl ester (purchased from Tokyo Chemical Industry Co., Ltd.) was used in place of m-toluidine in the same molar ratio. The target product was obtained by the same operation as in the synthesis example of 1,3-di-m-tolylurea. The melting point was 167-168 ° C. The chemical shift (δ ppm) in the proton NMR spectrum (400 MHz) measured in deuterated chloroform solvent was as follows. δ: 1.39 (t, 6H, J = 7.2Hz), 4.38 (q, 4H, 7.2Hz), 7.39 (t, 2H, J = 8.0Hz), 7.48 (brs, 2H), 7.74 (d, 2H, J = 7.6Hz), 7.82-7.90 (m, 4H)

[0108] Comparative Example 1 A reversible thermochromic composition was obtained by mixing 1 part of 2'-(2-chloroanilino)-6'-(dibutylamino)fluoran as a leuco dye, 4 parts of 1,3-diphenylurea (purchased from Tokyo Chemical Industry Co., Ltd.) as a color developer, and 25 parts of 4-benzyloxyphenylethyl caprate as a color change temperature regulator.

[0109] Comparative Example 2 A reversible thermochromic composition was obtained in the same manner as in Comparative Example 1, except that 4 parts of 1,3-diphenylthiourea (purchased from Tokyo Chemical Industry Co., Ltd.) was used as the color developer.

[0110] Example 1 A reversible thermochromic composition was obtained by mixing 1 part of 2'-(2-chloroanilino)-6'-(dibutylamino)fluoran as a leuco dye, 4 parts of 1,3-di(3-(trifluoromethyl)phenyl)urea as a color developer, and 25 parts of 4-benzyloxyphenylethyl caprate as a color change temperature regulator.

[0111] Example 2 A reversible thermochromic composition was obtained in the same manner as in Example 1, except that the compound obtained in Synthesis Example 2 was used as the color developer.

[0112] Example 3 A reversible thermochromic composition was obtained in the same manner as in Example 1, except that the compound obtained in Synthesis Example 3 was used as the developer.

[0113] Example 4 A reversible thermochromic composition was obtained in the same manner as in Example 1, except that 4 parts of 1,3-bis[4-(trifluoromethyl)phenyl]thiourea (purchased from Tokyo Chemical Industry Co., Ltd.) was used as the developer.

[0114] Example 5 A reversible thermochromic composition was obtained in the same manner as in Example 1, except that the compound obtained in Synthesis Example 4 was used as the developer.

[0115] Example 6 A reversible thermochromic composition was obtained in the same manner as in Example 1, except that the compound obtained in Synthesis Example 5 was used as the developer.

[0116] Example 7 A reversible thermochromic composition was obtained in the same manner as in Example 1, except that the compound obtained in Synthesis Example 6 was used as the developer.

[0117] Example 8 A reversible thermochromic composition was obtained in the same manner as in Example 1, except that the compound obtained in Synthesis Example 7 was used as the developer.

[0118] Example 9 A reversible thermochromic composition was obtained in the same manner as in Example 1, except that the compound obtained in Synthesis Example 8 was used as the developer.

[0119] Example 10 A reversible thermochromic composition was obtained in the same manner as in Example 1, except that the compound obtained in Synthesis Example 9 was used as the developer.

[0120] Example 11 A reversible thermochromic composition was obtained in the same manner as in Example 1, except that the compound obtained in Synthesis Example 10 was used as the developer.

[0121] Example 12 A reversible thermochromic composition was obtained in the same manner as in Example 1, except that the compound obtained in Synthesis Example 11 was used as the developer.

[0122] Example 13 A reversible thermochromic composition was obtained in the same manner as in Example 1, except that the compound obtained in Synthesis Example 12 was used as the developer.

[0123] Example 14 A reversible thermochromic composition was obtained in the same manner as in Example 1, except that the compound obtained in Synthesis Example 13 was used as the developer.

[0124] Comparative Example 3 A composition was obtained in the same manner as in Example 1, except that the discoloration temperature regulator was not used.

[0125] Comparative Example 4 A composition was obtained in the same manner as in Example 3, except that the discoloration temperature regulator was not used.

[0126] Comparative Example 5 A composition was obtained in the same manner as in Example 11, except that the discoloration temperature regulator was not used.

[0127] <Color development sensitivity> 30 parts of each composition obtained in the comparative examples and examples was dissolved in 120 parts of methyl ethyl ketone, and then coated on fine paper (Shirogane, manufactured by Nippon Paper Papylia Co., Ltd.) and left to cure overnight to prepare a measurement sample. The image density of the prepared measurement sample was measured using a spectrodensitometer / colorimeter (eXact) manufactured by X-Rite. The results are shown in Tables 1 and 2. Note that a higher image density value in this test indicates better color development sensitivity.

[0128] <Decolorization> The prepared measurement samples were pressed for 5 seconds at a heat source temperature of 70°C or 90°C using a thermal paper static color development tester manufactured by Okura Engineering Co., Ltd., and the decolorization was evaluated visually after the heat source was removed. The results are shown in Tables 1 and 2. The symbols used to evaluate the decolorization in this test are explained as follows: A: Significant decolorization was observed compared to the sample before pressing with the heat source. B: Decolorization was observed compared to the sample before pressing with the heat source. C: Almost no difference was observed compared to the sample before pressing with the heat source. D: No difference was observed compared to the sample before pressing with the heat source.

[0129]

[0130] As is clear from Table 1, the compounds of Examples 1 to 14 have at least one electron-withdrawing group or hydrogen-bonding group on the benzene ring adjacent to the NH group of the urea, thiourea, or sulfamide structure, thereby increasing the reactivity of the NH group with the leuco dye compared to Comparative Examples 1 and 2, and exhibiting sufficient color-developing sensitivity. Furthermore, because the electron-withdrawing group is not directly bonded to the urea, thiourea, or sulfamide structure, the reactivity with the leuco dye is not too strong, resulting in good decolorization properties (i.e., decolorization properties). Therefore, the compounds described herein can be used as color developers for non-phenolic reversible thermochromic compositions that combine excellent color-developing sensitivity and decolorization properties. Furthermore, as is clear from Table 2, the compounds do not exhibit decolorization properties when a color-change temperature regulator is not included.

Claims

1. A reversible thermochromic composition comprising a developer containing a compound represented by the following formula (1), a leuco dye, and a color-changing temperature regulator: 【Chemistry 1】 (In the above formula (1), a, a', b, A, A', and X are as follows: a is an integer selected from 0 to 5; a' is an integer selected from 0 to 5; b is 0 or 1; X is -C(=Y)- or -SO ２ - and the sum of a and a′ is 1 or more, A and A' each independently represent an electron-withdrawing group or a hydrogen-bonding group; Y is O or S. However, the benzene ring in the above formula (1) may have a substituent other than A or A'.

2. The reversible thermochromic composition according to claim 1, wherein in the formula (1), at least one of A or A' is an electron-withdrawing group selected from a halogen atom, a nitrile group, a carboxyl group, an alkyl group having at least one fluoro group, and an oxycarbonyl group, a carbonyl group, an aminocarbonyl group, an aminosulfonyl group, a sulfinyl group, and a sulfonyl group, each of which may have a substituent.

3. The reversible thermochromic composition according to claim 2, wherein in the formula (1), at least one of A or A' is an electron-withdrawing group selected from a fluoro group, an alkyl group having at least one fluoro group, and an oxycarbonyl group which may have a substituent.

4. The reversible thermochromic composition according to claim 1, wherein in the formula (1), at least one of A or A' is a hydrogen-bonding group selected from a carboxyl group, an amino group which may have a substituent, a carbonylamino group, a urea group, and a sulfonylamido group.

5. The reversible thermochromic composition according to any one of claims 1 to 4, wherein at least one of A or A' in formula (1) is bonded to the * position in formula (1).

6. The reversible thermochromic composition according to claim 4, wherein in formula (1), a is 1 or more, at least one A is bonded to the position * described in formula (1), the A bonded to the position * is a hydrogen bonding group selected from a carboxyl group, an amino group which may have a substituent, a carbonylamino group, a urea group, and a sulfonylamido group, and b is 0.

7. The reversible thermochromic composition according to any one of claims 1 to 4, wherein in formula (1), b is 1.

8. A microcapsule pigment comprising the reversible thermochromic composition according to any one of claims 1 to 4 encapsulated in a microcapsule.

9. A writing implement containing the reversible thermochromic composition according to any one of claims 1 to 4.

10. A toy comprising the reversible thermochromic composition according to any one of claims 1 to 4.

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