JP4920192B2 - Reversible thermochromic microcapsule pigment - Google Patents

Description

  The present invention relates to a reversible thermochromic microcapsule pigment. More specifically, the present invention relates to a reversible thermochromic microcapsule pigment having excellent light resistance.

Conventionally, there has been disclosed a microcapsule pigment including a reversible thermochromic composition comprising a reaction medium that reversibly causes an electron-donating reaction between an electron-donating color-forming organic compound and an electron-accepting compound in a specific temperature range. (For example, refer to Patent Document 1).
The above-described conventional microcapsule pigment is liable to cause a residual color caused by light irradiation in a decolored state and a fading caused by light irradiation in a colored state.
In order to solve the above-mentioned problems, it is conceivable to add an ultraviolet absorber, but although it is effective in improving the light resistance in the decolored state, the effect of improving the light resistance in the colored state is poor, and the color change is reversible. The reversible thermochromic microcapsule pigment, which is important to be generated, may have a significant loss of contrast during coloring and decoloring.
JP 2001-115153 A

  In the present invention, the conventional reversible thermochromic microcapsule pigment, which cannot be achieved, may cause a problem such as fading or remaining color in any state of coloring and decoloring. There is no attempt to provide reversible thermochromic microcapsule pigments.

（式中、Ｒ_１、Ｒ_２はそれぞれ水素原子、炭素数２又は３のアルキル基、シクロアルキル基、又は、アリール基を示し、Ｒ_３、Ｒ_４はそれぞれ水素原子、アルキル基、又は、アリール基を示し、Ｒ_５、Ｒ_６はそれぞれ水素原子、アルキル基、アルコキシ基、又は、ハロゲン原子を示し、Ｘは、−ＮＨＣＯＲ_７、−ＮＨＣＯＯＲ_７、−ＮＨＣＯＮＨＲ_８を示し、Ｒ_７はアルキル基、シクロアルキル基、アリール基、Ｒ_８はアルキル基、シクロアルキル基、アリール基、アシル基から選ばれ、Ａ_１、Ａ_２、Ａ_３、Ａ_４のうち１つ又は２つは＝Ｎ−であり、他は＝ＣＨ−である。）

（式中、Ｒ_１、Ｒ_２、Ｒ_３、Ｒ_４はそれぞれ水素原子、アルキル基、シクロアルキル基、又は、アリール基を示し、Ｒ_５、Ｒ_６はそれぞれ水素原子、アルキル基、アルコキシ基、又は、ハロゲン原子を示し、Ｘは、−ＮＨＣＯＲ_７、−ＮＨＣＯＯＲ_７、−ＮＨＣＯＮＨＲ_８を示し、Ｒ_７はアルキル基、シクロアルキル基、アリール基、Ｒ_８はアルキル基、シクロアルキル基、アリール基、アシル基から選ばれ、Ａ_１、Ａ_２、Ａ_３、Ａ_４のうち１つ又は２つは＝Ｎ−であり、他は＝ＣＨ−である。） As described above, as a result of studying a reversible thermochromic microcapsule pigment that suppresses deterioration during color development and decoloration by light, the present inventor has found that (a) electron donating property is exhibited in a color development system based on an electron transfer reaction. As the chromatic organic compound, the lactone derivative represented by the general formula (1) or (2), the (b) electron accepting compound functioning as the developer, and (c) the former color development / decoloration at a specific temperature. The present invention has been completed by finding that a system in which a reaction medium generated in a region is compatible satisfies the above requirements.
That is, the reversible thermochromic composition of the present invention comprises (a) a lactone derivative of the following general formula (1) or (2) as an electron-donating color-forming organic compound, (b) an electron-accepting compound, (c) Requirements for a reversible thermochromic microcapsule pigment comprising a capsule wall membrane encapsulating a reversible thermochromic composition comprising a reaction medium that reversibly causes an electron transfer reaction by components (b) and (b) in a specific temperature range And

(In the formula, R ₁ and R ₂ each represent a hydrogen atom, an alkyl group having 2 or 3 carbon atoms, a cycloalkyl group, or an aryl group, and R ₃ and R ₄ represent a hydrogen atom, an alkyl group, or an aryl group, respectively. R ₅ and R ₆ each represent a hydrogen atom, an alkyl group, an alkoxy group, or a halogen atom, X represents —NHCOR ₇ , —NHCOOR ₇ , —NHCONHR ₈ , and R ₇ represents an alkyl group, A cycloalkyl group, an aryl group, and R ₈ are selected from an alkyl group, a cycloalkyl group, an aryl group, and an acyl group, and one or two of A ₁ , A ₂ , A ₃ , and A ₄ are ═N—. , Others are = CH-.)

(Wherein R ₁ , R ₂ , R ₃ and R ₄ each represent a hydrogen atom, an alkyl group, a cycloalkyl group or an aryl group, and R ₅ and R ₆ represent a hydrogen atom, an alkyl group and an alkoxy group, respectively. Or, it represents a halogen atom, X represents —NHCOR ₇ , —NHCOOR ₇ , —NHCONHR ₈ , R ₇ represents an alkyl group, a cycloalkyl group, an aryl group, R ₈ represents an alkyl group, a cycloalkyl group, an aryl group, Selected from acyl groups, one or two of A ₁ , A ₂ , A ₃ , A ₄ is ═N— and the other is ═CH—.

  In the present invention, by using a specific lactone derivative as an electron-donating color-developing organic compound, it is possible to prevent photodegradation that occurs in either a colored state or a decolored state. A reversible color-changing microcapsule pigment excellent in contrast can be obtained. In particular, a reversible color-changing microcapsule pigment having a function that does not cause browning due to photodegradation in a decolored state or that does not cause a decrease in color density when colored again is obtained.

The reversible thermochromic microcapsule pigment is composed of (a) an electron donating color-forming organic compound, (b) an electron-accepting compound, and (c) a reaction medium that determines the temperature at which the color reaction of the two occurs. A reversible thermochromic composition containing at least a component contained in a microcapsule is effective, and examples include a heat-decolorable microcapsule pigment that decolorizes by heating from a colored state.
The microcapsule pigment discolors before and after a predetermined temperature (discoloration point), exhibits a decolored state in a temperature range above the complete decolorization temperature, and exhibits a color development state in a temperature range below the complete color development temperature. Of these, only one specific state exists at room temperature. That is, the other state is maintained while the heat or cold necessary to develop the state is applied, but when the heat or cold is no longer applied, the state returns to the state exhibited in the normal temperature range. The width is relatively small (ΔHA = 1 to 7 ° C.) (see FIG. 1).

In addition, a large hysteresis characteristic (ΔH _B = 8 to 70 ° C.), that is, the shape of a curve plotting a change in color density due to a temperature change is opposite to the case where the temperature is raised from the lower temperature side than the color change temperature range. The color changes following a path that differs greatly depending on whether the temperature is lowered from the high temperature side, and the color development state in the low temperature range below the complete color development temperature (t ₁ ), or the high temperature above the complete decoloration temperature (t ₄ ). Even if the decoloring state in the region is a heat decoloring type microcapsule pigment that can store and retain colors in a specific temperature range [temperature range between t _{2 and} t ₃ (substantially two-phase holding temperature range)] Good (see FIG. 2).
In FIG. 2, the color density-temperature curve will be described in detail. The change of the color density due to the temperature change proceeds along the arrow. Here, A is a point indicating a density at a temperature T ₄ (hereinafter referred to as a complete color erasing temperature) reaching a complete color erasing state, and B is a temperature T ₃ (hereinafter referred to as a color erasing start temperature) at which a complete color development state can be maintained. C is a point indicating a density at a temperature T ₂ (hereinafter referred to as a color development start temperature) at which a completely decolored state can be maintained, and D is a temperature T ₁ at which a complete color developed state is reached. This is a point indicating the density at (hereinafter referred to as a complete color development temperature).
The length of the line segment EF is a scale indicating the discoloration contrast, and the length of the line segment HG is a temperature width indicating the degree of hysteresis (hereinafter referred to as hysteresis width ΔH). It is easy to maintain each state before and after the color change.
Here, Δt, which is the difference between T ₄ and T ₃ , or the difference between T ₂ and T ₁ , is a scale indicating the sensitivity of discoloration, and a range of 1 ° C. to 10 ° C. is practical.
In order to allow only one of the states before and after the color change to exist in the normal temperature range, the hysteresis width is 40 to 70 ° C., preferably 50 to 70 ° C., more preferably 60 to 70 ° C. The color temperature (t ₄ ) is 40 ° C. or higher, preferably 45 ° C. or higher, more preferably 50 ° C. or higher, and the color development start temperature (t ₂ ) is 5 ° C. or lower, preferably 0 ° C. or lower, more preferably − 5 ° C. or lower.

  Further, as the electron-accepting compound, a specific alkoxyphenol compound having a linear or side chain alkyl group having 3 to 18 carbon atoms may be used (Japanese Patent Laid-Open Nos. 11-129623 and 11-5973), This is a heating color developing type microcapsule pigment using hydroxybenzoic acid ester (Japanese Patent Laid-Open No. 2001-105732) or gallic acid ester (Japanese Patent Publication No. 51-44706, Japanese Patent Laid-Open No. 2003-253149). (See FIG. 3).

The components (A), (B), and (C) will be specifically described below.
The lactone derivative represented by the general formula (1) or (2) of the (a) electron donating color-forming organic compound exhibits a blue to green color tone.
As the compound represented by the general formula (1),
3- (2-acetamido-4-dipropylaminophenyl) -3- (1-methyl-2-phenylindol-3-yl) -4-azaphthalide,
3- (2-acetamido-4-dipropylaminophenyl) -3- (1-ethyl-2-phenylindol-3-yl) -4-azaphthalide,
3- (2-acetamido-4-dipropylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide,
3- (2-acetamido-4-dipropylaminophenyl) -3- (1-octyl-2-methylindol-3-yl) -4-azaphthalide,
3- (2-acetamido-4-dipropylaminophenyl) -3- (1-pentyl-2-methylindol-3-yl) -4-azaphthalide,
Examples include 3- (2-acetamido-4-diethylaminophenyl) -3- (1-octyl-2-methylindol-3-yl) -4-azaphthalide and the like.
Moreover, as a compound shown by General formula (2),
3- (2-acetamido-4-diethylaminophenyl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide,
3- (2-acetamido-4-dipropylaminophenyl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide,
3- (2-acetamido-4-dibutylaminophenyl) -3- (2-ethoxy-4-dibutylaminophenyl) -4-azaphthalide,
3- (2-acetamido-4-dibutylaminophenyl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide,
3- (2-acetamido-4-dibutylaminophenyl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide,
3- (2-acetamido-4-dipentylaminophenyl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide,
Examples include 3- (2-acetamido-4-ethylphenylaminophenyl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide.

The (b) electron-accepting compound includes a group of compounds having active protons, a group of pseudo-acidic compounds (a group of compounds that are not acids but act as acids in the composition and cause the component (i) to develop color), There is a group of compounds having pores.
Examples of compounds having active protons include monophenols to polyphenols as compounds having phenolic hydroxyl groups, and alkyl groups, aryl groups, acyl groups, alkoxycarbonyl groups, carboxy groups and esters thereof as substituents. Or what has an amide group, a halogen group, etc., phenol-aldehyde condensation resin etc., such as a bis type and a tris type phenol, are mentioned.
Moreover, the metal salt of the compound which has the said phenolic hydroxyl group may be sufficient.

Specific examples are given below.
Phenol, o-cresol, tertiary butyl catechol, nonylphenol, n-octylphenol, n-dodecylphenol, n-stearylphenol, p-chlorophenol, p-bromophenol, o-phenylphenol, 4- (4- (1- Methylethoxyphenyl) sulfonylphenol, 4- (4-butyloxyphenyl) sulfonylphenol, 4- (4-pentyloxyphenyl) sulfonylphenol, 4- (4-hexyloxyphenyl) sulfonylphenol, 4- (4-heptyloxy) Phenyl) sulfonylphenol, 4- (4-octyloxyphenyl) sulfonylphenol, n-butyl p-hydroxybenzoate, n-octyl p-hydroxybenzoate, resorcin, dodecyl gallate,
1,1-bis (4'-hydroxyphenyl) ethane,
1,1-bis (4′-hydroxyphenyl) -2-methylpropane,
1,1-bis (4′-hydroxyphenyl) -3-methylbutane,
1,1-bis (4′-hydroxyphenyl) n-hexane,
1,1-bis (4′-hydroxyphenyl) n-heptane,
1,1-bis (4′-hydroxyphenyl) n-octane,
1,1-bis (4′-hydroxyphenyl) n-nonane,
1,1-bis (4′-hydroxyphenyl) n-decane,
1,1-bis (4′-hydroxyphenyl) n-dodecane,
1-phenyl-1,1-bis (4′-hydroxyphenyl) ethane,
2,2-bis (4'-hydroxyphenyl) propane,
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) n-heptane,
2,2-bis (4'-hydroxyphenyl) n-nonane,
2,2-bis (4'-hydroxyphenyl) hexafluoropropane,
2,2-bis (4'-hydroxy-3-methylphenyl) propane,
4,4 ', 4 "-methylidenetrisphenol,
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-triphenylphenol],
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-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],
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-di-hydroxyphenyl) methylene] bis [2,6-dimethylphenol],
4,4 ′-(1-phenylethylidene) bisphenol,
5,5 ′-(1-methylethylidene) bis [1-phenyl-2-ol],
4,4 ', 4 "-methylidenetrisphenol,
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],
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-tert-butyl-4-hydroxyphenyl) sulfide,
Bis (3-pentyl-4-hydroxyphenyl) sulfide,
Bis (3-hexyl-4-hydroxyphenyl) sulfide,
Bis (3-heptyl-4-hydroxyphenyl) sulfide,
Bis (4-hydroxyphenyl) sulfide,
Bis (5-octyl-2-hydroxyphenyl) sulfide and the like can be mentioned.
The compounds having a phenolic hydroxyl group can exhibit the most effective thermochromic properties, but their metal salts, aromatic carboxylic acids and aliphatic carboxylic acids having 2 to 5 carbon atoms and their metal salts, carboxylic acids It may be a compound selected from acid metal salts, acidic phosphate esters and their metal salts, 1,2,3-triazole and derivatives thereof.
Furthermore, a fluoroalcohol compound can also be used, and is exemplified below.
2-hydroxyhexafluoroisopropylbenzene,
1,3-bis (2-hydroxyhexafluoroisopropyl) benzene,
1,4-bis (2-hydroxyhexafluoroisopropyl) benzene,
1,3-bis (2-hydroxymethyl-hexafluoroisopropyl) benzene,
1,3-bis (3-hydroxy-1,1-bistrifluoromethylpropyl) benzene,
1,4-bis (2-hydroxymethyl-hexafluoroisopropyl) benzene,
1,4-bis (3-hydroxy-1,1-bistrifluoromethylpropyl) benzene,
2-hydroxymethyl-hexafluoroisopropylbenzene,
3-hydroxy-1,1-bistrifluoromethylpropylbenzene,

The component (c) of the reaction medium that causes the electron transfer reaction by the components (a) and (b) to occur reversibly in a specific temperature range will be described. Examples of the component (c) include alcohols, esters, ketones, ethers, and acid amides.
In addition, when applied to microencapsulation and secondary processing, those having a low molecular weight will evaporate out of the capsule system when subjected to a high heat treatment. Preferably used.
As the alcohols, aliphatic monovalent saturated alcohols having 10 or more carbon atoms are effective. Specifically, decyl alcohol, undecyl alcohol, dodecyl alcohol, tridecyl alcohol, tetradecyl alcohol, pentadecyl alcohol, hexadecyl Alcohol, heptadecyl alcohol, octadecyl alcohol, eicosyl alcohol, docosyl alcohol, etc. are mentioned.

  As the esters, esters having 10 or more carbon atoms are effective, and any combination of a monovalent carboxylic acid having an aliphatic and alicyclic or aromatic ring and a monohydric alcohol having an aliphatic and alicyclic or aromatic ring. Esters, aliphatic and alicyclic rings obtained from any combination of esters, aliphatic and alicyclic or aromatic polyvalent carboxylic acids obtained from the above and monohydric alcohols having aliphatic and alicyclic or aromatic rings Or esters obtained from any combination of monovalent carboxylic acid having an aromatic ring and aliphatic and alicyclic or polyhydric alcohol having an aromatic ring, specifically, ethyl caprylate, octyl caprylate, capryl Stearyl acid, myristyl caprate, docosyl caprate, 2-ethylhexyl laurate, n-decyl laurate, myris 3-methylbutyl acid, cetyl myristate, isopropyl palmitate, neopentyl palmitate, nonyl palmitate, cyclohexyl palmitate, n-butyl stearate, 2-methylbutyl stearate, 3,5,5-trimethylhexyl stearate, stearin N-undecyl acid, pentadecyl stearate, stearyl stearate, cyclohexylmethyl stearate, isopropyl behenate, hexyl behenate, lauryl behenate, behenyl behenate, cetyl benzoate, stearyl p-tert-butylbenzoate, dimyristyl phthalate , Distearyl phthalate, dimyristyl oxalate, dicetyl oxalate, dicetyl malonate, dilauryl succinate, dilauryl glutarate, diundecyl adipate, azelaic acid Lauryl, di- (n-nonyl) sebacate, dineopentyl 1,18-octadecylmethylenedicarboxylate, ethylene glycol dimyristate, propylene glycol dilaurate, propylene glycol distearate, hexylene glycol dipalmitate, 1,5-pentane Diol distearate, 1,2,6-hexanetriol trimyristate, 1,4-cyclohexanediol didecyl, 1,4-cyclohexanedimethanol dimyristate, xylene glycol dicaprate, xylene glycol distearate, etc. Can be mentioned.

In addition, esters of saturated fatty acids and branched fatty alcohols, unsaturated fatty acids or branched or substituted saturated fatty acids and esters of fatty alcohols having 16 or more carbon atoms, cetyl butyrate, stearyl butyrate and Ester compounds selected from behenyl butyrate are also effective.
Specifically, 2-ethylhexyl butyrate, 2-ethylhexyl behenate, 2-ethylhexyl myristate, 2-ethylhexyl caprate, 3,5,5-trimethylhexyl laurate, 3,5,5-trimethylhexyl palmitate, 3,5,5-trimethylhexyl stearate, 2-methylbutyl caproate, 2-methylbutyl caprylate, 2-methylbutyl caprate, 1-ethylpropyl palmitate, 1-ethylpropyl stearate, 1-ethylpropyl behenate, 1-ethylhexyl laurate, 1-ethylhexyl myristate, 1-ethylhexyl palmitate, 2-methylpentyl caproate, 2-methylpentyl caprylate, 2-methylpentyl caprate, 2-methylpentyl laurate, 2-stearate Mechi Butyl, 2-methylbutyl stearate, 3-methylbutyl stearate, 1-methylheptyl stearate, 2-methylbutyl behenate, 3-methylbutyl behenate, 1-methylheptyl stearate, 1-methylheptyl behenate, caproic acid 1 -Ethylpentyl, 1-ethylpentyl palmitate, 1-methylpropyl stearate, 1-methyloctyl stearate, 1-methylhexyl stearate, 1,1-dimethylpropyl laurate, 1-methylpentyl caprate, palmitic acid 2-methylhexyl, 2-methylhexyl stearate, 2-methylhexyl behenate, 3,7-dimethyloctyl laurate, 3,7-dimethyloctyl myristate, 3,7-dimethyloctyl palmitate, 3, stearate 7-Jime Luoctyl, 3,7-dimethyloctyl behenate, stearyl oleate, behenyl oleate, stearyl linoleate, behenyl linoleate, 3,7-dimethyloctyl erucate, stearyl erucate, isostearyl erucate, cetyl isostearate, isostearic acid Examples include stearyl acid, 2-methylpentyl 12-hydroxystearate, 2-ethylhexyl 18-bromostearate, isostearyl 2-ketomyristate, 2-ethylhexyl 2-fluoromyristate, cetyl butyrate, stearyl butyrate, and behenyl butyrate. It is done.

前記一般式（３）で示されるエステル化合物は、分子内に芳香環を２個有するアルコール化合物と、炭素数４以上の飽和又は不飽和脂肪酸とから構成されるエステル化合物である。
式中のＲは炭素数４以上のアルキル基又はアルケニル基を示すが、好ましくは炭素数６〜２０のアルキル基、更に好ましくは炭素数８〜１８のアルキル基である。
前記化合物として具体的には、ブタン酸−４−ベンジルオキシフェニルエチル、ペンタン酸−４−ベンジルオキシフェニルエチル、ヘキサン酸−４−ベンジルオキシフェニルエチル、ヘプタン酸−４−ベンジルオキシフェニルエチル、オクタン酸−４−ベンジルオキシフェニルエチル、ノナン酸−４−ベンジルオキシフェニルエチル、デカン酸−４−ベンジルオキシフェニルエチル、ウンデカン酸−４−ベンジルオキシフェニルエチル、ドデカン酸−４−ベンジルオキシフェニルエチル、トリデカン酸−４−ベンジルオキシフェニルエチル、テトラデカン酸−４−ベンジルオキシフェニルエチル、ペンタデカン酸−４−ベンジルオキシフェニルエチル、ヘキサデカン酸−４−ベンジルオキシフェニルエチル、ヘプタデカン酸−４−ベンジルオキシフェニルエチル、オクタデカン酸−４−ベンジルオキシフェニルエチル、ノナデカン酸−４−ベンジルオキシフェニルエチル、エイコサン酸−４−ベンジルオキシフェニルエチル、トリコサン酸−４−ベンジルオキシフェニルエチル、テトラコサン酸−４−ベンジルオキシフェニルエチル、ペンタコサン酸−４−ベンジルオキシフェニルエチル、ヘキサコサン酸−４−ベンジルオキシフェニルエチル、ヘプタコサン酸−４−ベンジルオキシフェニルエチル、オクタコサン酸−４−ベンジルオキシフェニルエチル、ノナコサン酸−４−ベンジルオキシフェニルエチル、トリアコンタン酸−４−ベンジルオキシフェニルエチル、ヘントリアコンタン酸−４−ベンジルオキシフェニルエチルを例示できる。 In addition, with respect to the color density-temperature curve, a large hysteresis characteristic (a curve plotting changes in color density due to temperature changes differs depending on whether the temperature is changed from the low temperature side to the high temperature side or when the temperature is changed from the high temperature side to the low temperature side. In order to obtain a reversible thermochromic composition exhibiting color memory properties, the carboxylic acid ester compound exhibiting a ΔT value (melting point-cloud point) of 5 ° C. or more and less than 50 ° C., for example, in the molecule A carboxylic acid ester having a substituted aromatic ring, an ester of a carboxylic acid having an unsubstituted aromatic ring and an aliphatic alcohol having 10 or more carbon atoms, a carboxylic acid ester having a cyclohexyl group in the molecule, a fatty acid having 6 or more carbon atoms, and Unsubstituted aromatic alcohol or phenol ester, fatty acid having 8 or more carbon atoms and branched aliphatic alcohol or ester, dicarboxylic acid and aromatic alcohol or Esters of branched fatty alcohols, dibenzyl cinnamate, heptyl stearate, didecyl adipate, dilauryl adipate, dimyristyl adipate, dicetyl adipate, distearyl adipate, trilaurin, trimyristin, tristearin, dimyristin, distearin, etc. Are preferably used.
Further, color density using diesters composed of a saturated linear dibasic acid having 12 or more carbon atoms and a monohydric alcohol having an aromatic ring in the molecule, or an ester compound represented by the general formula (3) A heat-erasable microcapsule pigment that changes color by exhibiting a wide hysteresis width (40 to 70 ° C.) with respect to the temperature curve is also applicable.

The ester compound represented by the general formula (3) is an ester compound composed of an alcohol compound having two aromatic rings in the molecule and a saturated or unsaturated fatty acid having 4 or more carbon atoms.
R in the formula represents an alkyl group or alkenyl group having 4 or more carbon atoms, preferably an alkyl group having 6 to 20 carbon atoms, more preferably an alkyl group having 8 to 18 carbon atoms.
Specific examples of the compound include butanoic acid-4-benzyloxyphenylethyl, pentanoic acid-4-benzyloxyphenylethyl, hexanoic acid-4-benzyloxyphenylethyl, heptanoic acid-4-benzyloxyphenylethyl, and octanoic acid. -4-benzyloxyphenylethyl, nonanoic acid-4-benzyloxyphenylethyl, decanoic acid-4-benzyloxyphenylethyl, undecanoic acid-4-benzyloxyphenylethyl, dodecanoic acid-4-benzyloxyphenylethyl, tridecanoic acid -4-benzyloxyphenylethyl, tetradecanoic acid-4-benzyloxyphenylethyl, pentadecanoic acid-4-benzyloxyphenylethyl, hexadecanoic acid-4-benzyloxyphenylethyl, heptadecanoic acid-4-benzylo Cyphenylethyl, octadecanoic acid-4-benzyloxyphenylethyl, nonadecanoic acid-4-benzyloxyphenylethyl, eicosanoic acid-4-benzyloxyphenylethyl, tricosanoic acid-4-benzyloxyphenylethyl, tetracosanoic acid-4-benzyl Oxyphenylethyl, pentacosanoic acid-4-benzyloxyphenylethyl, hexacosanoic acid-4-benzyloxyphenylethyl, heptacosanoic acid-4-benzyloxyphenylethyl, octacosanoic acid-4-benzyloxyphenylethyl, nonacosanoic acid-4-benzyl Examples thereof include oxyphenyl ethyl, triacontanoic acid-4-benzyloxyphenylethyl, and hentriacontanoic acid-4-benzyloxyphenylethyl.

Fatty acid ester compound obtained from an odd aliphatic monohydric alcohol having 9 or more carbon atoms and an aliphatic carboxylic acid having an even carbon number, n-pentyl alcohol or n-heptyl alcohol and an even aliphatic carboxylic acid having 10 to 16 carbon atoms A fatty acid ester compound having a total carbon number of 17 to 23 obtained from an acid is also effective.
Specifically, n-pentadecyl acetate, n-tridecyl butyrate, n-pentadecyl butyrate, n-undecyl caproate, n-tridecyl caproate, n-pentadecyl caproate, n-nonyl caprylate, n-undecyl caprylate, N-tridecyl caprylate, n-pentadecyl caprylate, n-heptyl caprate, n-nonyl caprate, n-undecyl caprate, n-tridecyl caprate, n-pentadecyl caprate, n-pentyl laurate, lauric acid n-heptyl, n-nonyl laurate, n-undecyl laurate, n-tridecyl laurate, n-pentadecyl laurate, n-pentyl myristate, n-heptyl myristate, n-nonyl myristate, n-myristate Undecyl, n-tridecyl myristate, N-pentadecyl ristinate, n-pentyl palmitate, n-heptyl palmitate, n-nonyl palmitate, n-undecyl palmitate, n-tridecyl palmitate, n-pentadecyl palmitate, n-nonyl stearate, stearic acid n-undecyl, n-tridecyl stearate, n-pentadecyl stearate, n-nonyl eicosanoate, n-undecyl eicosanoate, n-tridecyl eicosanoate, n-pentadecyl eicosanoate, n-nonyl behenate, n-behenate Examples include undecyl, n-tridecyl behenate, and n-pentadecyl behenate.

As the ketones, aliphatic ketones having a total carbon number of 10 or more are effective, and 2-decanone, 3-decanone, 4-decanone, 2-undecanone, 3-undecanone, 4-undecanone, 5-undecanone, 2 -Dodecanone, 3-dodecanone, 4-dodecanone, 5-dodecanone, 2-tridecanone, 3-tridecanone, 2-tetradecanone, 2-pentadecanone, 8-pentadecanone, 2-hexadecanone, 3-hexadecanone, 9-heptadecanone, 2-pentadecanone 2-octadecanone, 2-nonadecanone, 10-nonadacanone, 2-eicosanone, 11-eicosanone, 2-heneicosanone, 2-docosanone, laurone, stearone and the like.
Further, arylalkyl ketones having a total carbon number of 12 to 24, such as n-octadecanophenone, n-heptadecanophenone, n-hexadecanophenone, n-pentadecanophenone, n-tetradecane. Nophenone, 4-n-dodecanacetophenone, n-tridecanophenone, 4-n-undecanoacetophenone, n-laurophenone, 4-n-decanoacetophenone, n-undecanophenone, 4-n-nonylacetophenone, n-decanophenone, 4-n-octylacetophenone, n-nonanophenone, 4-n-heptylacetophenone, n-octanophenone, 4-n-hexylacetophenone, 4-n-cyclohexylacetophenone, 4-tert-butylpropiophenone , N-heptaphenone, 4-n-pentylacetofu Non, cyclohexyl phenyl ketone, benzyl -n- butyl ketone, 4-n-butyl acetophenone, n- hexanophenone, 4-isobutyl acetophenone, 1-acetonaphthone, 2-acetonaphthone, cyclopentyl phenyl ketone.

  As ethers, aliphatic ethers having a total carbon number of 10 or more are effective, and include dipentyl ether, dihexyl ether, diheptyl ether, dioctyl ether, dinonyl ether, didecyl ether, diundecyl ether, didodecyl ether, ditrityl ether. Decyl ether, ditetradecyl ether, dipentadecyl ether, dihexadecyl ether, dioctadecyl ether, decane diol dimethyl ether, undecane diol dimethyl ether, dodecane diol dimethyl ether, tridecane diol dimethyl ether, decane diol diethyl ether, undecane diol diethyl ether, etc. Can be mentioned.

  Acid amides include acetamide, propionic acid amide, butyric acid amide, caproic acid amide, caprylic acid amide, capric acid amide, lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, oleic acid amide , Erucic acid amide, benzamide, caproic acid anilide, caprylic acid anilide, capric acid anilide, lauric acid anilide, myristic acid anilide, palmitic acid anilide, stearic acid anilide, behenic acid anilide, oleic acid anilide, erucic acid anilide, caproic acid N -Methylamide, caprylic acid N-methylamide, capric acid N-methylamide, lauric acid N-methylamide, myristic acid N-methylamide, palmitic acid N-methylamide, stearic acid N-methylamido , Behenic acid N-methylamide, oleic acid N-methylamide, erucic acid N-methylamide, lauric acid N-ethylamide, myristic acid N-ethylamide, palmitic acid N-ethylamide, stearic acid N-ethylamide, oleic acid N-ethylamide, laurin Acid N-butyramide, myristic acid N-butyramide, palmitic acid N-butyramide, stearic acid N-butyramide, oleic acid N-butyramide, lauric acid N-octylamide, myristic acid N-octylamide, palmitic acid N-octylamide, Stearic acid N-octylamide, oleic acid N-octylamide, lauric acid N-dodecylamide, myristic acid N-dodecylamide, palmitic acid N-dodecylamide, stearic acid N-dodecylamide, olei Acid N-dodecylamide, dilauric acid amide, dimyristic acid amide, dipalmitic acid amide, distearic acid amide, dioleic acid amide, trilauric acid amide, trimyristic acid amide, tripalmitic acid amide, tristearic acid amide, trioleic acid Amide, succinic acid amide, adipic acid amide, glutaric acid amide, malonic acid amide, azelaic acid amide, maleic acid amide, succinic acid N-methylamide, adipic acid N-methylamide, glutaric acid N-methylamide, malonic acid N-methylamide, Azelaic acid N-methylamide, succinic acid N-ethylamide, adipic acid N-ethylamide, glutaric acid N-ethylamide, malonic acid N-ethylamide, azelaic acid N-ethylamide, succinic acid N-butylamide, adipic acid N- Examples include butyramide, glutaric acid N-butyramide, malonic acid N-butyramide, adipic acid N-octylamide, adipic acid N-dodecylamide, and the like.

The reversible thermochromic composition is a compatible solution containing the components (a), (b), and (c) as essential components, and the ratio of each component is the concentration, color change temperature, color change form, and type of each component. In general, the component ratio at which desired characteristics can be obtained is (b) component 1 to (b) component 0.1 to 100, preferably 0.1 to 50, more preferably 0. 0.5 to 20, (C) Component 1 to 800, preferably 5 to 200, more preferably 5 to 100 (all the above-mentioned ratios are parts by weight).
Each component may be a mixture of two or more, and an antioxidant, an ultraviolet absorber, an infrared absorber, a dissolution aid, and the like can be added as long as the function is not hindered.

The homogeneous compatible mixture comprising at least the above three components is encapsulated in microcapsules to form a reversible thermochromic microcapsule pigment, and protected by a capsule membrane wall to chemistry of acidic substances, basic substances, peroxides, etc. Even if it comes into contact with a chemically active substance or other solvent component, its function is not deteriorated, and heat resistance stability can be improved.
Further, a secondary resin film may be provided on the surface of the microcapsule according to the purpose to impart durability, or the surface characteristics may be modified for practical use.
The microcapsules satisfy practicality in the range of an average particle size of 0.5 to 50 μm, preferably 0.5 to 30 μm, and more preferably 0.5 to 20 μm.
When the average value of the maximum outer diameter exceeds 50 μm, the microcapsule lacks dispersion stability and processability when blended into ink, paint, or thermoplastic resin.
On the other hand, in a system where the average value of the maximum outer diameter is 0.1 μm or less, it is difficult to show high color density.
In addition, by making the capsules into fine particles, the ΔH value can be further expanded compared with the ΔH of the homogeneous solution of the essential three-component composition.
For the microcapsules, the range of inclusions / wall film = 7/1 to 1/1 (weight ratio) is effective, and when the wall film ratio is larger than the above range, the color density and sharpness during color development deteriorate. The inclusion / wall membrane = 6/1 to 1/1 (weight ratio) is preferable.
The microencapsulation includes conventionally known isocyanate-based interfacial polymerization methods, in-situ polymerization methods such as melamine-formalin, in-liquid curing coating methods, phase separation methods from aqueous solutions, phase separation methods from organic solvents, melting There are a dispersion cooling method, an air suspension coating method, a spray drying method, and the like, which are appropriately selected according to use.
The microcapsule pigment can be mixed with a general dye (non-thermochromic) to exhibit a color change behavior from colored (1) to colored (2).

The reversible thermochromic microcapsule pigment is dispersed in a vehicle containing various additives as necessary, and is used for screen printing, offset printing, process printing, gravure printing, coater, tampo printing, etc., printing ink, brush coating, spraying Paint, electrostatic coating, electrodeposition coating, flow coating, roller coating, dip coating, etc., ink for inkjet, marking pen, ballpoint pen, fountain pen, brush pen, etc. It can be used as a reversible thermochromic liquid composition such as crayons, paints, cosmetics, and coloring liquids for fibers.
The material of the support is not specified and is all effective, and can be exemplified by paper, synthetic paper, fiber, fabric, synthetic leather, leather, plastic, glass, ceramic material, metal, wood, stone, etc. Not only the shape but also the uneven shape may be used.
In the case where a non-thermochromic colored layer (including an image) is previously formed on the support, the colored layer can be concealed by a temperature change, and the aspect of the change is further diversified. be able to.
Further, the reversible thermochromic microcapsule pigment can be used as a reversible thermochromic molding resin composition in the form of pellets, powders, or pastes by melt blending with thermoplastic resins, thermosetting resins, waxes and the like.
Using the molding resin, by means of general-purpose injection molding, extrusion molding, blow molding, cast molding, etc., any form of three-dimensional modeled object, film, sheet, plate, filament, rod-shaped object, pipe, etc. A molded body is obtained.
Examples of the additive include a crosslinking agent, a curing agent, a drying agent, a plasticizer, a viscosity modifier, a dispersant, a light stabilizer, an anti-settling agent, a smoothing agent, a gelling agent, an antifoaming agent, a matting agent, a penetrating agent, A pH adjuster, a foaming agent, a coupling agent, a moisturizer, a fungicide, a preservative, a rust inhibitor, and the like can be given.
Among the light stabilizers, examples of the ultraviolet absorber include benzophenone ultraviolet absorbers, salicylic acid ultraviolet absorbers, cyanoacrylate ultraviolet absorbers, benzotriazole ultraviolet absorbers, oxalic acid anilide ultraviolet absorbers, and the like. Examples of the antioxidant include hindered amine antioxidants, phenolic antioxidants, sulfur antioxidants, and phosphoric acid antioxidants.
In addition, a general dye / pigment (non-thermochromic property) may be blended in the liquid composition or the molding resin composition to exhibit a color change behavior from color (1) to color (2).
A layered product in which a reversible thermochromic layer is formed on a support with the liquid material, or a layer containing a light stabilizer and / or a transparent metallic luster pigment is laminated on the molded product to improve light resistance. Alternatively, a durability can be improved by providing a topcoat layer.
Examples of the transparent metallic luster pigment include natural mica, synthetic mica, glass pieces, alumina, and a pigment obtained by coating the surface of a transparent film piece with a metal oxide such as titanium oxide.

  Specific examples of products using the reversible thermochromic microcapsule pigment include dolls or animal figure toys, doll or animal figure toy hair, doll houses and furniture, clothes, hats, bags, shoes, etc. Products, accessory toys, plush toys, drawing toys, puzzle toys such as toys, jigsaw puzzles, building toys, block toys, clay toys, fluid toys, tops, bowls, musical instrument toys, cooking toys, gun toys, capture toys, background toys , Toys imitating vehicles, animals, plants, buildings, food, etc., T-shirts, trainers, blouses, dresses, swimwear, raincoats, ski wear, footwear such as shoes and shoelaces, handkerchiefs, towels, furoshiki Fabric accessories such as carpets, curtains, curtain strings, table hangers, rugs, cushions, frames, artificial ornaments such as artificial flowers, bedding, pillows, mattresses and other bedding, rings Accessories such as bracelets, tiaras, earrings, hair stoppers, false nails, ribbons, scarves, writing utensils, stamps, erasers, underlays, rulers, stationery items such as adhesive tape, lipsticks, eye shadows, manicures, hair dyes, artificial nails , Cosmetics such as paint for artificial nails, cups, dishes, chopsticks, spoons, forks, pots, frying pans and other kitchenware, calendars, labels, cards, recording materials, various printed materials to prevent forgery, books such as picture books, gloves, Necktie, hat, bag, packaging container, embroidery thread, exercise equipment, fishing equipment, toothbrush, coaster, watch, glasses, lighting equipment, air conditioning equipment, musical instrument, warmer, cool storage agent, photo stand, wallet bag, umbrella, Examples include furniture, vehicles, buildings, temperature detection indicators, and teaching tools.

Example 1
Preparation of reversible thermochromic microcapsule pigment (i) 3- (2-acetamido-4-dipropylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide as component 1.5 parts by weight, 3.0 parts by weight of 1,1-bis (4′-hydroxyphenyl) 2-methylpropane as component (b), 2,2-bis (4′-hydroxyphenyl) hexafluoropropane A reversible thermochromic composition comprising 0 parts by weight and 50.0 parts by weight of 4-benzyloxyphenylethyl caprate as component (c) is uniformly heated and dissolved, and an aromatic polyisocyanate prepolymer 30 is used as a wall film material. 0.08 parts by weight and 40.0 parts by weight of co-solvent were emulsified and dispersed in 8% polyvinyl alcohol aqueous solution to form fine droplets, and the reaction was continued at 65 ° C for about 1 hour. Then, 2.5 parts by weight of a water-soluble aliphatic modified amine was added, and stirring was further continued for 6 hours to obtain a reversible thermochromic microcapsule pigment suspension.
The suspension was centrifuged to isolate a reversible thermochromic microcapsule pigment.
The microcapsule pigment has a complete color development temperature (T ₁ ) of −15 ° C., a color development start temperature (T ₂ ) of −8 ° C., a decolorization start temperature (T ₃ ) of 45 ° C., and a complete color erase temperature (T ₄ ) of The temperature is 64 ° C., and the color changes from blue to colorless as the temperature changes.

Example 2
Preparation of reversible thermochromic microcapsule pigment (I) As a component, 1.5 parts by weight of 3- (2-acetamido-4-diethylaminophenyl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, (B) As a component, 3.0 parts by weight of 1,1-bis (4′-hydroxyphenyl) 2-methylpropane, 5.0 parts by weight of 2,2-bis (4′-hydroxyphenyl) hexafluoropropane, ) A reversible thermochromic composition composed of 50.0 parts by weight of 4-benzyloxyphenylethyl caprate as a component is uniformly heated and dissolved, and 30.0 parts by weight of an aromatic polyisocyanate prepolymer as a wall film material is added. The solution mixed with 40.0 parts by weight of the solvent was emulsified and dispersed in 8% polyvinyl alcohol aqueous solution to form fine droplets, and the reaction was continued at 65 ° C. for about 1 hour. Thereafter, 2.5 parts by weight of a water-soluble aliphatic modified amine was added, and the mixture was further stirred for 6 hours to obtain a reversible thermochromic microcapsule pigment suspension.
The suspension was centrifuged to isolate a reversible thermochromic microcapsule pigment.
The microcapsule pigment has a complete color development temperature (T ₁ ) of −17 ° C., a color development start temperature (T ₂ ) of −9 ° C., a decolorization start temperature (T ₃ ) of 42 ° C., and a complete color erase temperature (T ₄ ) of The temperature is 64 ° C., and the color changes from green to colorless according to the temperature change.

Comparative Example 1
Preparation of reversible thermochromic microcapsule pigment (a) As component (3- (4-ethylphenylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide 1. 1.0 part by weight, (b) component 1,1-bis (4′-hydroxyphenyl) 2-methylpropane 3.0 part by weight, 2,2-bis (4′-hydroxyphenyl) hexafluoropropane A reversible thermochromic composition comprising 0 parts by weight and 50.0 parts by weight of 4-benzyloxyphenylethyl caprate as component (c) is uniformly heated and dissolved, and an aromatic polyisocyanate prepolymer 30 is used as a wall film material. 0.08 parts by weight and 40.0 parts by weight of co-solvent were emulsified and dispersed in 8% polyvinyl alcohol aqueous solution to form fine droplets, and the reaction was continued at 65 ° C for about 1 hour. Then, 2.5 parts by weight of a water-soluble aliphatic modified amine was added, and stirring was further continued for 6 hours to obtain a reversible thermochromic microcapsule pigment suspension.
The suspension was centrifuged to isolate a reversible thermochromic microcapsule pigment.
The microcapsule pigment has a complete color development temperature (T ₁ ) of −18 ° C., a color development start temperature (T ₂ ) of −7 ° C., a color erase start temperature (T ₃ ) of 48 ° C., and a complete color erase temperature (T ₄ ) of The temperature is 64 ° C., and the color changes from blue to colorless as the temperature changes.

Comparative Example 2
Preparation of reversible thermochromic microcapsule pigment (a) 1.0 part by weight of 3,3-bis (4-diethylamino-2-ethoxyphenyl) -4-azaphthalide as component (1,) 1,1-bis as component (b) (4'-Hydroxyphenyl) 2-methylpropane 3.0 parts by weight, 2,2-bis (4'-hydroxyphenyl) hexafluoropropane 5.0 parts by weight, (c) capric acid 4-benzyloxyphenyl as component A solution obtained by uniformly heating and dissolving a reversible thermochromic composition comprising 50.0 parts by weight of ethyl and mixing 30.0 parts by weight of an aromatic polyvalent isocyanate prepolymer and 40.0 parts by weight of a co-solvent as a wall film material Is emulsified and dispersed in an aqueous solution of 8% polyvinyl alcohol to form fine droplets, and the reaction is continued at 65 ° C. for about 1 hour. Then, 2.5 parts by weight of a water-soluble aliphatic modified amine is added, Further, stirring was continued for 6 hours to obtain a reversible thermochromic microcapsule pigment suspension.
The suspension was centrifuged to isolate a reversible thermochromic microcapsule pigment.
The microcapsule pigment has a complete color development temperature (T ₁ ) of −18 ° C., a color development start temperature (T ₂ ) of −7 ° C., a decolorization start temperature (T ₃ ) of 45 ° C., and a complete color erase temperature (T ₄ ) of The temperature is 64 ° C., and the color changes from green to colorless according to the temperature change.

Comparative Example 3
Preparation of reversible thermochromic microcapsule pigment (a) As component (3- (4-ethylphenylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide 1. 1.0 part by weight, (b) component 1,1-bis (4′-hydroxyphenyl) 2-methylpropane 3.0 part by weight, 2,2-bis (4′-hydroxyphenyl) hexafluoropropane 0 parts by weight, (c) component as component (50.0 parts by weight) 4-benzyloxyphenylethyl caprate, UV absorber as 2- (3-tert-butyl-5-methyl-2-hydroxyphenyl) -5-chlorobenzo 1.0 part by weight of triazole, bis (1,2,2,6,2- (3,5-di-tert-butyl-4-hydroxybenzyl) -2-n-butylmalonate as a light stabilizer 6-pentamethyl-4-piperidyl) 0.2 parts by weight of a reversible thermochromic composition is uniformly heated and dissolved, and 30.0 parts by weight of an aromatic polyvalent isocyanate prepolymer as a wall film material; The solution mixed with 0 parts by weight was emulsified and dispersed in 8% polyvinyl alcohol aqueous solution to form fine droplets, and the reaction was continued at 65 ° C. for about 1 hour, and then 2.5 parts by weight of a water-soluble aliphatic modified amine was added. Further, stirring was continued for 6 hours to obtain a reversible thermochromic microcapsule pigment suspension.
The suspension was centrifuged to isolate a reversible thermochromic microcapsule pigment.
The microcapsule pigment has a complete color development temperature (T ₁ ) of −17 ° C., a color development start temperature (T ₂ ) of −9 ° C., a decolorization start temperature (T ₃ ) of 44 ° C., and a complete color erase temperature (T ₄ ) of The temperature is 64 ° C., and the color changes from blue to colorless as the temperature changes.

Preparation of test sample 40 parts by weight of the microcapsule pigment obtained in Examples and Comparative Examples were mixed uniformly with 52 parts by weight of an ethylene-vinyl acetate copolymer resin emulsion, 5 parts by weight of a thickener, and 3 parts by weight of a leveling agent. A reversible thermochromic screen ink was obtained.
Screen printing was performed on a high-quality paper using the above-described inks with a 180 mesh screen plate, and a reversible thermochromic layer was provided to obtain a test sample (reversible thermochromic print).

Light resistance test A (colored state)
Using a xenon arc light resistance tester (Table Sun XT75, manufactured by Suga Test Instruments Co., Ltd.) in a state where the reversible thermochromic layer of each test sample is colored, light irradiation is performed for 24 hours under the condition of irradiance of about 180 W / m ^2. went.
Light resistance test B (decolored state)
Light irradiation for 24 hours under the condition of irradiance of about 180 W / m ² using a xenon arc light resistance tester (Table Sun XT75, manufactured by Suga Test Instruments Co., Ltd.) with the reversible thermochromic layer of each test sample decolored. Went.
The thermal discoloration function (density and residual color) after the test was visually evaluated.
The light resistance test results are shown in the following table.

The explanation about the symbols of the light resistance test results in the table is as follows.
Light resistance test A (colored state)
(Double-circle): There is no fall of a color density compared with the initial stage, and browning is not seen even if decolored.
○: There is no decrease in color density compared to the initial stage, and slight browning is observed when the color is erased.
(Triangle | delta): The fall of a color density is seen compared with the initial stage, and a slight browning will be seen if decoloring.
X: A decrease in color density is observed as compared with the initial stage, and a remarkable browning is observed when the color is erased.
Light resistance test B (decolored state)
○: No browning was observed compared to the initial stage, and the color density slightly decreased when the color was developed.
Δ: Slight browning is observed compared to the initial stage, and the color density is slightly decreased when the color is developed.
▲: Browning was observed compared to the initial stage, and the color density decreased when the color was developed.
X: The thermochromic function is not exhibited due to significant browning and a decrease in color density.

  From the above test results, all the samples using the reversible thermochromic microcapsule pigment of the present invention produced almost no fading at the time of color development or residual color at the time of decoloration, while the reversible thermochromic property prepared in the comparative example. All samples using microcapsule pigments have undergone problems such as significant browning during decoloring or complete loss of thermochromic function, which is an important requirement for reversible thermochromic microcapsule pigments. And did not satisfy the contrast when erasing.

It is explanatory drawing which shows the discoloration behavior of a heat decoloring type reversible thermochromic microcapsule pigment. It is explanatory drawing which shows the discoloration behavior of the heat decoloring type reversible thermochromic microcapsule pigment having color memory. It is explanatory drawing which shows the discoloration behavior of a heat coloring type reversible thermochromic microcapsule pigment.

t ₁ Complete color development temperature of reversible thermochromic microcapsule pigment with heat decoloring type t ₂ Color development start temperature of reversible thermochromic microcapsule pigment with heat decoloration type t ₃ Reversible thermochromic microcapsule pigment with heat decoloration type Decoloration start temperature of t ₄ Complete decolorization temperature of reversible thermochromic microcapsule pigment of heat decoloring type T ₁ Complete decoloration temperature of reversible thermochromic microcapsule pigment of ₁ heating color developing type T ₂ Reversible heat of color developing type of heat decoloring type Discoloration start temperature of the color-changing microcapsule pigment T ₃ Color development start temperature of the reversible thermochromic microcapsule pigment of the ₃ heating coloring type T ₄ Color development temperature of the reversible thermochromic microcapsule pigment of the ₄ heating coloring type

Claims (2)

(A) As an electron donating color-forming organic compound, a lactone derivative of the following general formula (1) or (2), (b) an electron accepting compound, (c) an electron transfer reaction by the components (a) and (b) above A reversible thermochromic microcapsule pigment comprising a capsule wall membrane encapsulating a reversible thermochromic composition comprising a reaction medium that reversibly occurs in a specific temperature range.

(In the formula, R ₁ and R ₂ each represent a hydrogen atom, an alkyl group having 2 or 3 carbon atoms, a cycloalkyl group, or an aryl group, and R ₃ and R ₄ represent a hydrogen atom, an alkyl group, or an aryl group, respectively. R ₅ and R ₆ each represent a hydrogen atom, an alkyl group, an alkoxy group, or a halogen atom, X represents —NHCOR ₇ , —NHCOOR ₇ , —NHCONHR ₈ , and R ₇ represents an alkyl group, A cycloalkyl group, an aryl group, and R ₈ are selected from an alkyl group, a cycloalkyl group, an aryl group, and an acyl group, and one or two of A ₁ , A ₂ , A ₃ , and A ₄ are ═N—. , Others are = CH-.)

(Wherein R ₁ , R ₂ , R ₃ and R ₄ each represent a hydrogen atom, an alkyl group, a cycloalkyl group or an aryl group, and R ₅ and R ₆ represent a hydrogen atom, an alkyl group and an alkoxy group, respectively. Or, it represents a halogen atom, X represents —NHCOR ₇ , —NHCOOR ₇ , —NHCONHR ₈ , R ₇ represents an alkyl group, a cycloalkyl group, an aryl group, R ₈ represents an alkyl group, a cycloalkyl group, an aryl group, Selected from acyl groups, one or two of A ₁ , A ₂ , A ₃ , A ₄ is ═N— and the other is ═CH—.   The reversible thermochromic microcapsule pigment according to claim 1, comprising a light stabilizer.

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