JP2001031884A - Reversible thermochromic pigment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a reversible thermochromic pigment capable of exhibiting such reversible thermochromism that color development with high intensity is realized when colored and retained color is not detected when achromatized, and improved in heat resistance by adding an electron donative chromogenic organic compound, a specific electron acceptable compound, and a thermochromic transition temperature-controlling agent. SOLUTION: This reversible thermochromic pigment contains (A) an electron donative chromogenic organic compound, (B) electron acceptable compounds comprising one, two or more compounds which are selected from bisphenol compounds of formulae I and II [(m) is 5-30; (n) is 0-2; X and Y are each H, a 1-4C alkyl or cyclohexyl] and have a molecular weight of >=250, and (C) a thermochromic transition temperature-controlling agent determining the temperature at which thermochromic reaction of the component A with the component B occurs. The pigment preferably comprises a pigment having a form of microcapsule microencapsulating the revesible therochromic composition containing the components A, B and C. A weight ratio of the reversible thermochromic composition to a microcapsule shell material used for coating the thermochromic composition is preferably in the range of 7/1 to 1/1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a reversible thermochromic pigment. More specifically, it relates to a reversible thermochromic pigment having significantly improved heat resistance.

[0002]

2. Description of the Related Art Conventionally, several proposals have been disclosed regarding a thermochromic pigment containing (a) an electron-donating color-forming organic compound, (b) an electron-accepting compound, and (c) a color-changing temperature regulator. Has been put into practical use (Japanese Patent Publication No. 51-4470).
No. 8, JP-A-62-156355, etc.). As the component (b), compounds having a phenolic hydroxyl group include monophenols and polyphenols, and examples of the substituent thereof include an alkyl group, an aryl group, an acyl group, an alkoxycarbonyl group, and a halogen. ing. Further, it is disclosed that alcohols, esters, ketones, ethers and the like can be applied as the component (c).

[0003]

The above (b)
In the relationship between the component and the component (c), the component (b)
The thermochromic performance greatly depends on the solubility of the components. More specifically, in a system in which the compound having a (b) phenolic hydroxyl group has poor solubility in the component (c), the color residue at the time of decoloring becomes large. Particularly, when the component (c) is an ester system, it is significantly affected. The component (b) disclosed in the prior art is a phenol compound having a relatively high polarity, and has poor solubility in low-polar esters, and it is difficult to satisfy the color density at the time of color development.
In addition, when actually used as a thermochromic pigment, in a process where high heat is applied or in an applied product that is exposed to high heat,
(B) Sublimation or volatilization of a part of the component deteriorates the intended thermochromic property. The present invention solves the above-mentioned disadvantages, exhibits high color density at the time of color development, exhibits reversible thermochromic properties with no color residue at the time of decoloration, and sublimates or volatilizes phenol components against high heat load. It is an object of the present invention to provide a heat-resistant reversible thermochromic pigment which suppresses the occurrence of a thermochromic pigment and continuously develops the desired thermochromic function without impairing it.

[0004]

The present invention relates to (a) an electron-donating color-forming organic compound, (b) an electron-accepting compound, and (c) a discoloration temperature which determines the temperature at which the color reaction of the two occurs. In the reversible thermochromic pigment containing a regulator, the (b) electron-accepting compound is selected from bis-type phenol compounds represented by the following general formulas (1) and (2), and has at least one of a molecular weight of 250 or more. A reversible thermochromic pigment, which is a compound of at least one kind, is required. General formula (1)

Embedded image [Wherein, m = 5 to 30 (linear or branched), n = 0 to 2,
X and Y represents any of an alkyl group or a cyclohexyl group hydrogen, C ₁ -C ₄ (straight or branched). General formula (2)

Embedded image Further, the reversible thermochromic pigment includes a reversible thermochromic pigment containing (a) an electron-donating color-forming compound, (b) an electron-accepting compound, and (c) a color-changing temperature regulator that determines the temperature at which the color reaction of the two occurs. A pigment in the form of microcapsules in which the thermochromic composition is encapsulated in microcapsules; reversible thermochromic composition / microcapsule wall film = 7/1 to 1/1 (weight ratio); reversible heat The discolorable pigment is required to be a pigment having a non-circular cross-sectional shape, a pigment in the form of microcapsules having a depression on at least a part of the outer surface, and the like.

In the above, the component (b) is a compound in which a long-chain alkyl group is introduced into a binder group connecting a phenyl group as shown in the general formula (1), or a compound as shown in the general formula (2). Function as a reaction medium by applying a compound into which a halogen group is introduced (c)
It has a high solubility for the components, and the component (a) reacts stably in the system to repeated heating and cooling, resulting in high-density color development and decoloring with no color residue. It can be repeatedly and continuously expressed. In addition, the introduction of the long-chain alkyl group or the halogen group increases the molecular weight, and when high heat is applied, sublimation or volatilization of the component (b) is suppressed. It can be effectively expressed continuously without impairing the function.

[0006] The thermochromic pigment of the present invention is characterized in that
(B) The three essential components of (c) are blended with a binder resin to form a granular material (for example, a solid solution formed by blending with a thermoplastic resin), and the outer surface of the granular material is coated with another resin. Although it may be, a pigment in the form of microcapsules in which the thermochromic composition containing the essential three components is encapsulated in microcapsules, a high-concentration color developing property,
It is suitable in terms of decoloring without leaving color, protection against chemicals and solvents, and the like. Further, the pigment in the form of a microcapsule may have a perfect circular shape, but a non-circular cross-sectional shape, more preferably a form having a depression on at least a part of the outer surface is effective. By making a flat pigment form having a non-circular cross-sectional shape, at the time of secondary processing to apply the pigment, for example, by applying a printing ink containing the pigment, a system requiring high heat treatment, or in a thermoplastic polymer In a system that requires a process of melt-blending the pigment, the wall film is elastically deformed in response to the thermal expansion and contraction of the capsule, and has an action of suppressing the destruction of the capsule wall film. It functions effectively as a tough capsule form thermochromic pigment that protects the composition and retains the desired thermochromic function. The synergistic effect of the effect of the non-circular cross section and the effect of the specific phenol compound gives a thermochromic pigment with remarkably excellent heat resistance. Furthermore, in the thermochromic pigment, it is preferable that the thermochromic composition / microcapsule wall film is in the range of 7/1 to 1/1 (weight ratio). When the ratio of the thermochromic composition is larger than the above range, the thickness of the microcapsule wall film becomes too thin, and the protective function of the thermochromic composition when high heat is applied is reduced. On the other hand, when the ratio of the microcapsule wall film is larger than the above range, the protective function is not affected, but the thermochromic function cannot be sufficiently exhibited, which is not preferable. Incidentally, microencapsulation, conventionally known interfacial polymerization method, interfacial polycondensation, in situ method, coacervate method and the like, known encapsulation methods are applied, aggregation, coalescence, interfacial polymerization method is less likely to occur, Alternatively, the interfacial polycondensation method is suitably applied. As the wall film, a conventionally known epoxy resin film, polyurethane film, polyurethane film and the like are effective. Further, a secondary resin film may be further 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 thermochromic pigment in the present invention has an average particle diameter [(long diameter +
Minor axis) / 2] is in the range of 0.5 μm to 20 μm, preferably 0.5 to 15 μm, and more preferably 1 to 10 μm.
Is effective in terms of the sharpness of discoloration, durability, workability and the like. If it is less than 0.5 μm, even if a thermochromic pigment microencapsulated in a state of being suspended in an aqueous medium can be obtained, isolation of the encapsulated pigment by means such as filtration or centrifugation is difficult, and strength is high. Is insufficient. On the other hand, in a system having an average particle diameter of more than 15 μm, it is difficult to satisfy the blending suitability.

Next, the component (a) applied to the present invention, that is, the electron-donating color-forming organic compound will be exemplified. As the electron-donating color-forming organic compound, conventionally known compounds are appropriately selected, and diphenylmethanephthalides, fluorans, diphenylmethaneazaphthalides, indolylphthalides, phenylindolphthalides, phenylindolyl Examples thereof include azaphthalides, styrinoquinolines, diazarhodamine lactones, pyridines, quinazolines, bisquinazolines, and the like, which are effective in expressing fluorescent yellow to red color.

Next, one of the main issues of the present invention, (b)
The electron accepting compound will be described. As the component (b), one or two or more compounds having a molecular weight of 250 or more selected from the bis-type phenol compounds represented by the general formula (1) or (2) are effective. Is exemplified. The number in parentheses added to the terminal of a compound indicates the molecular weight of the compound. 1,1-bis (4′-hydroxyphenyl) -3-methylbutane (256) 1,1-bis (4′-hydroxyphenyl) n-pentane (256) 1,1-bis (4′-hydroxyphenyl) n -Hexane (270) 1,1-bis (4'-hydroxyphenyl) n-heptane (284) 1,1-bis (4'-hydroxyphenyl) n-octane (298) 1,1-bis (4'- (Hydroxyphenyl) n-nonane (312) 1,1-bis (4′-hydroxyphenyl) n-decane (326) 1,1-bis (4′-hydroxyphenyl) n-dodecane (354) 2,2-bis (4′-hydroxyphenyl) n-heptane (284) 2,2-bis (4′-hydroxyphenyl) n-nonane (312) 2,2-bis (4′-hydroxyphenyl) hexafluoro Lopan (336) 2,2-bis (4'-hydroxyphenyl) -4-methylpentane (270) 2,2-bis (4'-hydroxyphenyl) n-octane (298) 1,1-bis (4 ' -Hydroxyphenyl) 2-ethylhexane (298) 2,2-bis (3'-methyl-4'-hydroxyphenyl) -4-methylpentane (298) 2,2-bis (3'-methyl-4'-) (Hydroxyphenyl) n-tridecane (368) 2,2-bis (3′-methyl-4′-hydroxyphenyl) n-pentadecane (396) 2,2-bis (3′-cyclohexyl-4′-hydroxyphenyl) n -Butane (406) 2,2-bis (4'-hydroxyphenyl) -6,1
0,14-trimethylpentadecane (438) 1,1-bis (3'-cyclohexyl-4'-hydroxyphenyl) n-decane (518) and the like.

(C) Examples of the discoloration temperature regulator include conventionally known alcohols, esters, ketones, ethers, acid amides and the like. By selecting the color change temperature regulator, the size of the hysteresis width (ΔH) can be adjusted with respect to the temperature-color density curve. In a system having a small hysteresis width (ΔH), the color changes before and after the color change temperature, and only one specific state can exist in the room temperature range between the two states before and after the color change. That is, the other state is maintained while the heat or cold required for the state to develop is applied, but when the heat or cold is no longer applied, the state returns to the original state exhibited in the normal temperature range, The thermochromic behavior is shown. The following compounds can be given as examples that give the thermochromic behavior.

As alcohols, aliphatic monovalent saturated alcohols having 10 or more carbon atoms are effective, and specific examples are decyl alcohol, undecyl alcohol, dodecyl alcohol, tridecyl alcohol, tetradecyl alcohol, and pentadecyl alcohol. , Hexadecyl alcohol, heptadecyl alcohol, octadecyl alcohol, eicosyl alcohol, docosyl alcohol and the like.

As the esters, esters having 10 or more carbon atoms are effective, such as monohydric carboxylic acids having aliphatic and alicyclic or aromatic rings and monohydric alcohols having aliphatic and alicyclic or aromatic rings. Esters and aliphatics obtained from any combination of esters, aliphatic and alicyclic or aromatic polyhydric carboxylic acids and aliphatic and alicyclic or aromatic monohydric alcohols obtained from any combination And esters obtained from any combination of a monovalent carboxylic acid having an alicyclic or aromatic ring and a polyhydric alcohol having an aliphatic and alicyclic or aromatic ring. Further, an ester of a saturated fatty acid and a branched aliphatic alcohol, an unsaturated fatty acid or an ester of a branched or substituted fatty acid having a branched or substituted aliphatic alcohol having 16 or more carbon atoms, cetyl butyrate, stearyl butyrate and Ester compounds selected from behenyl butyrate are also effective.

As ethers, aliphatic ethers having a total carbon number of 10 or more are effective, such as dipentyl ether,
Dihexyl ether, diheptyl ether, dioctyl ether, dinonyl ether, didecyl ether, diundecyl ether, didodecyl ether, ditridecyl ether, ditetradecyl ether, dipentadecyl ether, dihexadecyl ether, dioctadecyl ether, decane Examples thereof include diol dimethyl ether, undecane diol dimethyl ether, dodecane diol dimethyl ether, tridecane diol dimethyl ether, decane diol diethyl ether, and undecane diol diethyl ether.

The acid amides include caprylic amide,
And stearic acid amide.

Further, regarding the color density-temperature curve, ΔH (hysteresis width) is large, and a large hysteresis characteristic [the shape of the curve plotting the change in the color density due to the temperature change indicates that the temperature changes from a temperature lower than the color change temperature range. Unlike the case where the temperature is changed to the higher temperature side, when both curves are combined, it shows a loop shape) and discolors. The component (c) which is effective for expressing the color memory property and the thermochromic property depending on the temperature change The Japanese Patent Application Publication No. 4-17154 proposed by the present applicant earlier
Carboxylic acid ester compound having a ΔT value (melting point−cloud point) of 5 ° C. or more and less than 50 ° C., for example, a carboxylic acid ester having a substituted aromatic ring in a molecule, and an unsubstituted aromatic ring Esters of carboxylic acids and aliphatic alcohols having 10 or more carbon atoms, carboxylic acid esters containing a cyclohexyl group in the molecule, esters of fatty acids having 6 or more carbon atoms and unsubstituted aromatic alcohols or phenols, and fatty acids having 8 or more carbon atoms and branched Aliphatic alcohols or esters, esters of dicarboxylic acids with aromatic or branched aliphatic alcohols, dibenzyl cinnamate, heptyl stearate, didecyl adipate, dilauryl adipate, dimyristyl adipate, dicetyl adipate, distearyl adipate, Trilaurin, Trimyristin, Tristearin, Jimiri Chin, distearate, and the like.

Further, a 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, and n-pentyl alcohol disclosed in JP-A-7-33997 Alternatively, a fatty acid ester compound having 17 to 23 carbon atoms obtained from n-heptyl alcohol and an even aliphatic carboxylic acid having 10 to 16 carbon atoms 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, lauric acid n-pentyl, n-heptyl laurate, n-nonyl laurate, n-undecyl laurate, n-tridecyl laurate, n-pentadecyl laurate, n-pentyl myristate, n-myristate
Heptyl, n-nonyl myristate, n-myristate
Undecyl, n-tridecyl myristate, n-pentadecyl myristate, n-pentyl palmitate, n-heptyl palmitate, n-nonyl palmitate, n-undecyl palmitate, n-tridecyl palmitate, n-pentadecyl palmitate, Stearic acid n-
Nonyl, n-undecyl stearate, n stearic acid
-Tridecyl, n-pentadecyl stearate, n-nonyl eicosanoate, n-undelici eicosanoate, n-tridecyl eicosanate, n-pentadecyl eicosanoate, n-nonyl behenate, n-undecyl behenate, n-tridecyl behenate , N-pentadecyl behenate and the like.

As ketones, JP-A-7-17977
Aliphatic ketones having a total number of carbon atoms of 10 or more disclosed in JP-A-7 are effective, and 2-decanone, 3-decanone, 4-decanone, 2-undecanone, 3-undecanone, 4-undecanone, and 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, lauron, stearone and the like. Further, arylalkyl ketones having a total carbon number of 12 to 24, such as n-octadecanophenone, n-heptadecanophenone, n-hexadecanophenone, disclosed in JP-A-8-39936. n-pentadecanophenone, n-
Tetradecanophenone, 4-n-dodecaacetophenone, n-tridecanophenone, 4-n-undecanoacetophenone, n-laurophenone, 4-n-decanoacetophenone, n-undecanophenone, 4-n-nonyl Acetophenone, n-decanophenone, 4-n-octylacetophenone, n-nonanophenone, 4-n-heptylacetophenone, n-octanophenone, 4-n-
Hexyl acetophenone, 4-n-cyclohexyl acetophenone, 4-tert-butylpropiophenone,
n-heptaphenone, 4-n-pentyl acetophenone, cyclohexylphenyl ketone, benzyl-n-butyl ketone, 4-n-butyl acetophenone, n-hexanophenone, 4-isobutyl acetophenone, 1-acetonaphthone, 2-acetonaphthone, cyclopentyl phenyl ketone And the like.

The reversible thermochromic composition of the present invention is a compatibilizer containing the above three components (a), (b) and (c) as essential components, and the ratio of each component is determined by the concentration and the color change temperature. Although it depends on the discoloration form and the type of each component, in general, the component ratio at which desired characteristics can be obtained is as follows.
Component 0.1-100, preferably 0.1-50, (c)
The components are in the range of 5 to 100 (all the above parts are parts by weight).

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The above-mentioned (a), (b), (c)
Examples of the pigment in the form of microcapsules in which the reversible thermochromic composition containing the essential three components described above are encapsulated in microcapsules. In the examples, among the pigments in the form of microcapsules, any one of the forms illustrated in FIGS. 1 to 4 is applied, but a mixture of these forms or a form having a circular cross section may be used. The present invention is not limited to the embodiments.

[0019]

EXAMPLES The present invention will be described in more detail with reference to Examples. All parts in the examples are parts by weight.

Example 1 2-dibenzylamino-6-diethylaminofluoran (4 parts), 1,1-bis (4'-hydroxyphenyl) n-
Nonane (molecular weight 312) 10 parts, butyl stearate 5
0 parts of a reversible thermochromic composition, 20 parts of an aromatic isocyanate prepolymer as a wall film material, and 40 parts of ethyl acetate were added.
Emulsified in a 60% aqueous solution of gum arabic (60 ° C.). Here, thermochromic composition / microcapsule wall film = 3.2 / 1.
0 (weight ratio). Emulsion particle size of 5.0 to 10.0μ
After stirring at 65 ° C. for about 1 hour, 2.5 parts of a water-soluble aliphatic amine was added, and stirring was continued for 5 hours. The obtained microcapsules were isolated by a centrifugal separation method to obtain microcapsule-shaped thermochromic pigments containing a water-containing reversible thermochromic composition. The obtained pigment is colorless at about 22 ° C. or higher,
Green color was exhibited below 6 ° C.

Example 2 2- (4-diethylamino-2-ethoxyphenyl)-
3- (1-ethyl-2-methylindol-3-yl)
-4-azaphthalide 3 parts, 1,1-bis (4'-hydroxyphenyl) 2-ethylhexane (molecular weight 298) 6
, A reversible thermochromic composition consisting of 50 parts of stearyl caprate was dissolved by heating, and 10 parts of an epoxy resin and 50 parts of ethyl acetate were added as wall film materials, and a solution obtained by uniformly dissolving at 70 ° C was used as an aqueous protective colloid. Emulsified in the medium. Here, thermochromic composition / microcapsule wall film = 5.9 / 1.0
(Weight ratio). Emulsion particle diameter is 5.0 to 10.0 μm
The mixture was stirred at 65 ° C., 5 parts of a water-soluble aliphatic amine was added, and the mixture was further stirred at 90 ° C. for 8 hours. The obtained microcapsules were isolated by a centrifugal separation method to obtain microcapsule-shaped thermochromic pigments containing a water-containing reversible thermochromic composition. The pigment obtained was colorless at about 35 ° C. or higher and blue at 30 ° C. or lower.

Example 3 6- (Ethylisobutylamino) benzofluoran 3
Parts, 1,1-bis (4'-hydroxyphenyl) n-dodecane (molecular weight 354) 8 parts, butyl stearate 30
Parts, a reversible thermochromic composition composed of 20 parts of butyl palmitate and 30 parts of an aromatic isocyanate prepolymer, 40 parts of ethyl acetate was added, and the inclusion solution uniformly dissolved at 60 ° C. was added to a 15% aqueous gum arabic solution. (60 ° C.). Here, thermochromic composition / microcapsule wall film = 1.7 / 1.0 (weight ratio). The emulsified particle size is 5.
The stirring power was adjusted so as to be distributed in a range of 0 to 10.0 μm, and the mixture was reacted at 65 ° C. for about 1 hour. Then, 2.5 parts of a water-soluble aliphatic amine was added, and stirring was continued for 5 hours. The obtained microcapsules were isolated by a centrifugal separation method to obtain microcapsule-shaped thermochromic pigments containing a water-containing reversible thermochromic composition. The obtained pigment is approximately 12 ° C.
Above, colorless and pink at 8 ° C or less.

Comparative Example 1 1,1-bis (4'-hydroxyphenyl) of Example 2
2-Ethylhexane (molecular weight 298) was replaced with 2,2-bis (4′-hydroxyphenyl) n-propane (molecular weight 2).
A thermochromic pigment in the form of microcapsules was obtained in the same manner as in Example 2, except that 28) was used.

Heat resistance evaluation method 4 parts of the obtained microcapsules (water-containing state), 7 parts of an acrylate resin emulsion, and extender 7
Part, 1 part of a thickener and 1 part of a curing agent, a thermochromic ink was obtained. This ink was printed on a cotton cloth using a 109 mesh screen plate and dried to obtain a test piece. The obtained test pieces were subjected to a heat treatment for 10 minutes each from 130 ° C. to 220 ° C. in a thermostat, and the color density of the test pieces after the test was compared with that of the untested test pieces to determine the presence or absence of deterioration. As a result of testing the thermochromic pigment in the form of microcapsules obtained in Examples 1 to 3 and Comparative Example 1 based on the heat resistance evaluation method, the pigment of Example 1 was found to be 210 ° C.
The pigment of Example 2 was 200 ° C., and the pigment of Example 3 was 240 ° C.
° C and the pigment of Comparative Example 1 exhibited heat resistance of 130 ° C. The heat resistance means the maximum temperature at which the color density in the initial state is maintained.

Application Example 5 parts of the dried microcapsules obtained, 0.8 dispersant
Of a polyester resin (melting point 160 ° C.) was melt-kneaded at 180 ° C. with an extruder to obtain microcapsule-containing polyester pellets. The pellets obtained by using the four types of pigments of Examples 1 to 3 and Comparative Example 1 were heated and cooled to confirm the reversible thermochromic behavior. As a result, in the system to which the pigment of Example 1 was applied, , Green →→ colorless at about 20 ° C., in a system to which the pigment of Example 2 was applied, blue ← → colorless at about 35 ° C., and in a system to which the pigment of Example 3 was applied, pink で → colorless at about 10 ° C. However, in the system to which the pigment of Comparative Example 1 was applied, no color was formed even when cooled.

[0026]

As described above, the thermochromic pigment of the present invention suppresses sublimation or volatilization of the constituents even at a high temperature, so that the desired reversible thermochromic function can be continuously exhibited. Therefore, even in a printing field requiring a high-temperature treatment step, a printing ink containing the thermochromic pigment (heat-resistant reversible thermochromic ink) can be effectively applied to provide a thermochromic printed matter satisfying an intended function. . In addition, a system including a processing step in which high heat is applied in a printed state, for example, 150 ° C. or higher, and even 20 ° C.
It is effective in a system which is subjected to a high-temperature treatment of 0 ° C. or more, which includes bonding to a synthetic material such as shoes and bags, and a system including bonding to a metal surface such as aluminum or steel with a thermosetting ink. In addition, a resin composition obtained by melt-blending a thermochromic pigment in a thermoplastic polymer (heat-resistant reversible thermochromic resin composition) is formed by injection molding or extrusion molding. Thermochromic moldings), for example, in the process of obtaining thermochromic moldings of various forms by injection molding and thermochromic filaments by extrusion molding, high heat of about 150 to 250 ° C. is applied, In the system to which the thermochromic pigment of the present invention is applied, the desired reversible thermochromic function can be effectively exhibited without thermal deterioration. The thermochromic filament is applied to the fiber processing field as a fiber,
As thermochromic artificial hair, it is effective for processing doll head hair, animal toy body hair, entertainment wigs, false hair, piles for flocking, etc., and even if the processed object is exposed to high temperatures, The heat discoloration function is not impaired.

[Brief description of the drawings]

FIG. 1 shows an example of the reversible thermochromic pigment of the present invention.
FIG. 2A is an enlarged cross-sectional view of the appearance and FIG.

FIG. 2 shows another example of the reversible thermochromic pigment of the present invention.
FIG. 2A is an enlarged cross-sectional view of the appearance and FIG.

FIG. 3 shows another example of the reversible thermochromic pigment of the present invention.
FIG. 2A is an enlarged cross-sectional view of the appearance and FIG.

FIG. 4 shows another example of the reversible thermochromic pigment of the present invention.
FIG. 2A is an enlarged cross-sectional view of the appearance and FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermochromic pigment 11 Reversible thermochromic composition 12 Wall film 13 Depression

Claims (5)

[Claims] (1) an electron-donating color-forming organic compound,
(B) A reversible thermochromic pigment containing an electron-accepting compound and (c) a color-changing temperature regulator for determining the temperature at which the color reaction of the two occurs, wherein the (b) electron-accepting compound is represented by the following general formula ( A reversible thermochromic pigment, which is one or two or more compounds having a molecular weight of 250 or more selected from bis-type phenol compounds represented by 1) or (2). General formula (1) [Wherein, m = 5 to 30 (linear or branched), n = 0 to 2,
X and Y represents any of an alkyl group or a cyclohexyl group hydrogen, C ₁ -C ₄ (straight or branched). General formula (2) 2. The reversible thermochromic pigment comprises (a) an electron-donating color-forming compound, (b) an electron-accepting compound, and (c) a color-changing temperature regulator for determining a temperature at which a color reaction between the two occurs. The reversible thermochromic pigment according to claim 1, wherein the pigment is in the form of a microcapsule in which a reversible thermochromic composition containing is encapsulated in microcapsules. 3. The reversible thermochromic pigment according to claim 2, wherein the ratio of reversible thermochromic composition / microcapsule wall film is 7/1 to 1/1 (weight ratio). 4. The reversible thermochromic pigment according to claim 1, which is a pigment having a non-circular cross-sectional shape. 5. The reversible thermochromic pigment according to claim 1, which is a pigment in the form of microcapsules having a depression on at least a part of the outer surface.