JP3306609B2 - Thermochromic color memory composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to a thermochromic color memory composition. More specifically, it exhibits a large hysteresis characteristic due to a temperature change and exhibits a reversible color change of color development-decolorization, and even after removing the application of heat or cold required for the color change, either the colored state or the decolored state. The present invention relates to a thermochromic color-memorizing composition for maintaining the temperature in a normal temperature range in an alternating and reversible manner.

[0002]

2. Description of the Related Art The present applicant has previously proposed such a thermosensitive color-changeable color memory material (Japanese Patent Publication No. 4-171).
No. 54). In the thermochromic color memory material, the conventional general-purpose reversible thermochromic material changes color before and after the color change temperature, and only one specific state exists in the normal temperature range between the two states before and after the color change. I can't. In other words, the other state is maintained while the heat or cold required to develop the state is applied, but returns to the state exhibited in the normal temperature range when the heat or cold is not applied. On the other hand, both the color on the lower temperature side and the color on the higher temperature side than the discoloration temperature can be selectively maintained in the normal temperature range even after removing the adaptation of heat or cold required for discoloration. , Can be held alternately by applying heat or cold as needed, temperature-sensitive recording materials, toys,
It is applied to various fields such as decoration and printing.

[0003]

By the way, this kind of color memory effect can be achieved by using a specific one of compounds selected from esters which control a color reaction as disclosed in Japanese Patent Publication No. 4-17154. Because it is a thermochromic effect that can be expressed only by a system in which the compound of the present invention is applied as a component, the degree of utilization of this type of thermochromic material is restricted,
The discovery of new effective compounds has been awaited. The present inventors have pursued a compound that is a reaction medium for expressing the color memory effect, increase the degree of freedom of selection of the reaction medium, and furthermore, due to the high density at the time of color development and the good color erasure at the time of decolorization, The very high contrast seeks to further increase the utilization of this type of thermochromic color memory material.

[0004]

Means for Solving the Problems The present inventors have developed a system in which a compound selected from arylalkyl ketones having a total number of carbon atoms of 12 to 24 is used as a reaction medium for a color reaction, and has a hysteresis width (ΔH). The present invention has been found to exhibit a large thermochromic property, exhibit an effective color memory effect, and provide a very high contrast due to a high density at the time of color development and a good color erasure at the time of color erasure. Completed. The present invention provides (a) an electron-donating color-forming organic compound,
(B) an electron-accepting compound selected from compounds having a phenolic hydroxyl group ; (c) an arylalkyl ketone having a total carbon number of 12 to 24 for controlling the color reaction of the above (a) and (b) consisting homogeneous phase solution of the ternary compound selected from the class as an essential component, color density - related <br/> to the temperature curve, colored with cooling, it becomes colorless when heated co
A thermochromic color memory composition that exhibits a hysteresis width (ΔH) of 8 ° C. to 80 ° C. and changes color. Further, the arylalkyl ketone is a compound selected from phenylalkylketones, which is a thermochromic color memory composition. Further, the thermochromic color memory composition is encapsulated in microcapsules. It is required that the pigment is a microcapsule pigment.

FIG. 1 shows the hysteresis characteristics in the color density-temperature curve of the thermochromic color memory composition of the present invention.
Will be described. In FIG. 1, the vertical axis represents color density, and the horizontal axis represents temperature. The change in the color density due to the temperature change proceeds along the arrow. Here, A is a point indicating the density at the minimum temperature T ₄ (hereinafter, referred to as complete decoloring temperature) at which the complete color erasing state is reached, and B is the maximum temperature T ₃ (hereinafter, maximum) at which the complete color developing state can be maintained. (Referred to as holding temperature)
, C is the point indicating the density at the lowest temperature T ₂ (hereinafter, referred to as the minimum holding temperature) at which the complete decoloring state can be maintained, and D is the maximum temperature T _{1 at} which the complete coloration state is reached. (Hereinafter referred to as complete color temperature). At the temperature T _A , the two phases of the colored state E point and the decolored state F point coexist. This temperature T _A
Is the temperature range in which the coloration state and the decoloration state can coexist is the temperature range in which the discoloration can be maintained, and the length of the line segment EF is a measure of the discoloration contrast, and passes through the middle point of the line segment EF. The length of the line segment HG is a temperature width indicating the degree of hysteresis (hereinafter, referred to as hysteresis width ΔH), and the larger the ΔH value, the easier it is to maintain each state before and after discoloration. In the experiments of the present inventors, the ΔH value that can be held in each state before and after the practical discoloration is in the range of 8 ° C. to 80 ° C. Further, in the above, two phases of a coloration state and a decoloration state are substantially maintained,
It is effective that the temperature for practical use, that is, the temperature range between T ₃ and T ₂ including T _A is in the range of 2 ° C. or more and less than 80 ° C.

Furthermore, since the length of the line segment EF is a measure indicating the contrast, it represents the color density of states of the state and F E at brightness value V _E and V _F, the degree of contrast [Delta] V (V
_F− V _E ). The lightness values at the time of emission and decoloration are 0 for perfect black and 10 for perfect white in an achromatic array.
The Munsell color chart-based lightness value is divided so that the difference in brightness perception is equal, and the chromatic lightness is the achromatic lightness value whose chromatic lightness perception is equal to this. Is shown. That is, since the lightness value is smaller, the color is closer to black, and the lightness value is larger, the color is closer to white. Therefore, an index for measuring the density at the time of color development and the degree of residual color at the time of color erasing (degree of color erasure). The brightness difference (ΔV) is an index representing the contrast. Therefore, the difference in density between chromatic colors having the same hue can be expressed by this difference in lightness value regardless of the type of hue.

In the present invention, the proportions of the three components (a), (b) and (c) depend on the density, the discoloration temperature, the discoloration form and the type of each component. The component ratio obtained is such that component (a) is component 1 and component (b) component 0.
1 to 50, preferably 0.5 to 20, (c) components 1 to 8
00, preferably in the range of 5 to 200 (all the above parts are parts by weight). In addition, each component may be a mixture of two or more kinds, and an antioxidant, an ultraviolet absorber, a singlet oxygen quencher, an infrared absorber, as long as the function is not affected.
A dissolution aid or the like can be added. Also, by blending a general pigment (non-thermochromic), a color change from colored [1] to colored [2] can be provided.

The following are specific examples of compounds for each of the components (a), (b) and (c). As the component (A) of the present invention, ie, the electron-donating color-forming organic compound, conventionally known diphenylmethanephthalides, fluorans,
Diphenylmethane azaphthalide, indolyl phthalide, phenyl indolyl phthalide, phenyl indolyl azaphthalide, styrylquinoline, pyridine,
Quinazolines, bisquinazolines and the like. Hereinafter, these compounds will be exemplified. 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3-
(4-diethylaminophenyl) -3- (1-ethyl-
2-methylindol-3-yl) phthalide, 3- (4
-Diethylamino-2-methylphenyl) -3- (1-
Ethyl-2-methylindol-3-yl) -4-azaphthalide, 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindole-
3-yl) -4-azaphthalide, 2-N-cyclohexyl-N-benzylamino-6-diethylaminofluoran, 2-P-butylphenylamino-6-diethylamino-3-methylfluoran, 1,3-dimethyl- 6-diethylaminofluoran, 2-chloro-3-methyl-6
-Diethylaminofluoran, 3-dibutylamino-6
-Methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-xylidinofluoran, 2
-(2-chloroanilino) -6-dibutylaminofluoran, 3,6-dimethoxyfluoran, 3,6-di-n
-Butoxyfluoran, 1,2-benz-6-diethylaminofluoran, 1,2-benz-6-dibutylaminofluoran, 3- (butyl-2-methylindole-
3-yl) -3- (1-octyl-2-methylindol-3-yl) -1 (3H) isobenzofuranone,
2-benz-6-ethylisoamylaminofluoran,
2-methyl-6- (Np-tolyl-N-ethylamino) fluoran, 3,3-bis (1-n-butyl-2-
Methylindol-3-yl) phthalide, 3,3-bis (1-ethyl-2-methylindol-3-yl) phthalide, 2- (N-phenyl-N-methylamino) -6
(Np-tolyl-N-ethylamino) fluoran, 2
-(3'-trifluoromethylanilino) -6-diethylaminofluoran, 3-chloro-6-cyclohexylaminofluoran, 2-methyl-6-cyclohexylaminofluoran, 3-methoxy-4-dodecoxystyryl Quinoline, 4- (4'-methylbenzylaminophenyl) -pyridine, 2,6-diphenyl-4- (4'-dimethylaminophenyl) -pyridine, 2,6-bis (4'-methoxyphenyl) -4- (4′-dimethylaminophenyl) -pyridine, 2,6-dimethyl-3,5
-Biscarbethoxy-4- (4'-dimethylaminophenyl) -pyridine, 2- (2'-octoxyphenyl) -4- (4'-dimethylaminophenyl) -6-phenyl-pyridine, 2,6- Diethoxy-4- (4'-
Diethylaminophenyl) -pyridine, 2- (4′-dimethylaminophenyl) -4-methoxy-quinazoline,
2- (4'-dimethylaminophenyl) -4-phenoxy-quinazoline 2- (4'-dimethylaminophenyl)
-4- (4 "-nitrophenyloxy) -quinazoline, 2- (4'-phenylmethylaminophenyl) -4
-Phenoxy-quinazoline 2- (4'-piperidinophenyl) -4-phenoxy-quinazoline, 2- (4'-
Dimethylaminophenyl) -4- (4 ″ -chlorophenyloxy) -quinazoline, 2- (4′-dimethylaminophenyl) -4- (4 ″ -methoxyphenyloxy) -quinazoline, 4,4 ′-(ethylene Dioxy)-
Bis [2- (4-diethylaminophenyl) quinazoline], 4,4 '-[propylenedioxy (1,3)]-
Bis [2- (4-diethylaminophenyl) quinazoline], 4,4 '-[butyleneoxy (1,3)]-bis [2- (4-diethylaminophenyl) quinazoline], 4,4'-[butylene Oxy (1,4)]-bis [2- (4-diethylaminophenyl) quinazoline], 4,4 ′-(oxydiethylene) -bis [2-
(4-diethylaminophenyl) quinazoline], 4,
4'-ethylene-bis [2- (4-piperidinophenyl) quinazoline], 4,4'-ethylene-bis [2-
(4-di-n-propylaminophenyl) quinazoline], 4,4 '-(ethylenedioxy) -bis [2-
(4-di-n-butylaminophenyl) quinazoline],
4,4′-Cyclohexylene-bis [2- (4-diethylaminophenyl) quinazoline] and the like are preferably used.

[0009] Examples of the compound having a full Eno <br/> Le hydroxyl electron-accepting compound as the component (b), there are polyphenols from monophenols, further the alkyl group as its substituent, an aryl group, an acyl group , An alkoxycarbonyl group, a carboxy group and its ester or amide group,
Examples thereof include those having a halogen group and the like, and phenol-aldehyde condensation resins such as bis-type and tris-type phenols. Further, a metal salt of the compound having a phenolic hydroxyl group may be used.

Specific examples will be described below. Phenol, o-
Cresol, tert-butyl catechol, nonylphenol, n-octylphenol, n-dodecylphenol, n-stearylphenol, p-chlorophenol, p-bromophenol, o-phenylphenol, n-butyl p-hydroxybenzoate, p-hydroxy N-octyl benzoate, 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, 4-hydroxy-4′-isopropoxydiphenyl sulfone 1-
Phenyl-1,1-bis (4-hydroxyphenyl) ethane, 1,1-bis (4-hydroxyphenyl) -3-
Methylbutane, 1,1-bis (4-hydroxyphenyl) -2-methylpropane, 1,1-bis (4-hydroxyphenyl) n-hexane, 1,1-bis (4-hydroxyphenyl) n-heptane, , 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. Compounds having a phenolic hydroxyl group Ru can express most effective thermochromic characteristics.

Next, the total carbon number of the component (c) is 12 to 24.
Specific examples of the arylalkyl ketones are shown below. n-octadecanophenone, n-heptadecanophenone, n-hexadecanophenone, n-pentadecanophenone, n-tetradecanophenone, 4'-n-
Dodecanoacetophenone, n-tridecanophenone,
4'-n-undecanoacetophenone, n-laurophenone, 4'-n-decanoacetophenone, n-undecanophenone, 4'-n-nonylacetophenone, n-decanophenone, 4'-n-octylacetophenone, n
-Nonanophenone, 4'-n-heptyl acetophenone, n-octanophenone, 4'-n-hexyl acetophenone, 4'-n-cyclohexyl acetophenone,
4-tert-butylpropiophenone, n-heptanophenone, 4'-n-pentylacetophenone, cyclohexylphenylketone, benzyl-n-butylketone, 4'-n-butylacetophenone, n-hexanophenone, 4-isobutyl Examples include acetophenone, 1-acetonaphthone, 2-acetonaphthone, and cyclopentyl phenyl ketone. The component (C) of the present invention uses the above-mentioned arylalkyl ketones, and if necessary, other esters, as long as the hysteresis characteristics are not largely changed.
Alcohols, carboxylic acids, amides and the like can be added. In this case, the addition amount is preferably 50 parts or less (parts by weight) with respect to 50 parts of the arylalkyl ketone of the present invention in order to effectively exhibit the desired color memory effect.

The homogeneous compatible solution of the essential three-component composition (a), (b) and (c) can be encapsulated in microcapsules by a known microencapsulation technique, and can be converted into microparticles (0). 0.5 to 50 μm, preferably 1 to 30 μm), the ΔH value is the ΔH of the homogenous solution of the essential three-component composition.
ΔH can be further expanded as compared with. Further, by being protected by the capsule membrane wall, even if it comes into contact with a chemically active substance such as an acidic substance, a basic substance, a peroxide or other solvent components, its function is not reduced. Needless to say, heat stability can be maintained. Available microencapsulation techniques include interfacial polymerization, in situ polymerization, curing in liquid coating, phase separation from aqueous solutions, phase separation from organic solvents, melt dispersion cooling, and air suspension coating. ,
There are a spray drying method and the like, which are appropriately selected according to the application. The surface of the microcapsule may be provided with a secondary resin film depending on the purpose to impart durability, or the surface characteristics may be modified for practical use.

[0013]

The compound selected from the arylalkyl ketones of the present invention is used as a reaction medium for a color reaction by electron transfer, thereby exhibiting a thermochromic property having a large hysteresis width (ΔH) with respect to a color density-temperature curve. Further, it functions as a thermochromic composition having a very high contrast (ΔV) due to high density at the time of color development and good color erasure at the time of color erasing, and further includes the composition encapsulated in microcapsules. The ΔH effective for expressing the color memory effect is 8 ° C.
~ 80 ° C hysteresis characteristics. Although the theoretical elucidation of the action is still insufficient, high contrast is attributed to the fact that the arylalkyl ketones of the present invention have higher polarizability under the same melting point than ester compounds. Inferred. Further, the thermochromic behavior is repeatedly reproduced as seen in the thermochromic property measurement data of the examples described later.

[0014]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples. The method for producing the thermochromic color memory composition and the thermochromic color memory microcapsule pigment in each Example, the method for measuring the hysteresis characteristics by the temperature change of the microcapsule pigment, and the method for measuring the contrast are described below. explain. still,
Parts in the following formulation examples indicate parts by weight.

Example 1 Method for producing thermochromic color memory composition and method for measuring hysteresis characteristics 0.1 part of CVL as component (a), 0.1 part of bisphenol A as component (b), n-hexanophenone 2.5
The parts were mixed and heated to 120 ° C. with stirring to dissolve uniformly to obtain a three-component homogeneous solution. The homogeneous solution was packed in a transparent glass capillary tube having an inner diameter of 1 mm and a length of 78 mm to a height of 10 mm from the bottom of the capillary tube, and sealed to prepare a test body 1. The obtained specimen 1 was immersed in a beaker containing an antifreeze cooled to −10 ° C. up to a height of 40 mm from the bottom of the specimen 1, and a color density at each temperature was obtained. The antifreeze was heated from -10 ° C to + 1 ° C / min by using a handy cooler (manufactured by Thomas Scientific). When the color change of the test piece 1 was visually observed, the color density of the test piece 1, which exhibited a blue color up to 15 ° C., decreased every time it was heated from 15 ° C. (T ₃ ), and at 26 ° C. It became completely colorless and transparent (T ₄ ), and its transparency was maintained even when the temperature was raised to 40 ° C. Next, the specimen 1 in the state where the temperature was raised to 40 ° C. was reduced by −1.
When cooled at a rate of ° C / min, the colorless and transparent state was exhibited without any change up to 8 ° C. However, the color was colored pale blue at a temperature of 8 ° C or less (T ₂ ), and the color density increased with cooling. ,
The color was completely blue at 4 ° C (T ₁ ), and the color density at 4 ° C was maintained even when cooled to -10 ° C.

Examples 2 to 11 Hysteresis characteristics were measured in the same manner as in Example 1. (C) applied to the production of the thermochromic color memory composition
The components, T ₁ , T ₂ , T ₃ , T ₄ , T _H (the temperature at the midpoint of the color density in the coloring process), T _G (the temperature at the midpoint of the color density in the decoloring process), and ΔH (the line Table 1 shows the respective values of HG). The component (c) is as shown in Table 1, and the components (a) and (b) and other samples and their parts by weight are the same as in Example 1.

[Table 1]

Example 12 Method for producing thermosensitive color-changeable color-memory microcapsule pigment (a) As an electron-donating color-forming organic compound, 3-dibutylamino-6-methyl-7-anilinofluoran 3.0
Part, as a (b) phenol compound, 2,2-bis (4
-Hydroxyphenyl) propane 8.0 parts, (c) n-
A three-component solution consisting of 50.0 parts of laurophenone was heated and dissolved at 120 ° C. to form a homogeneous solution, and a mixed solution of 10 parts of Epon 828 (epoxy resin manufactured by Yuka Shell Epoxy Co., Ltd.) and 10 parts of methyl ethyl ketone Then, the mixture is added dropwise to 100 parts of a 10% aqueous gelatin solution, and the mixture is stirred so as to become fine droplets. A solution prepared by dissolving 5 parts of a separately prepared curing agent Epicure U (an amine adduct of an epoxy resin manufactured by Yuka Shell Epoxy Co., Ltd.) in 45 parts of water was gradually added to the stirring solution, Keep the liquid temperature at 80 ° C for about 5
Stirring was continued for an hour to obtain a stock solution of microcapsules. By centrifuging the stock solution, the water content is about 40% by weight.
A thermosensitive color-changing color memory microcapsule pigment having an average particle diameter of 10 μm, which changes from black to colorless, was obtained.

Method for measuring hysteresis characteristics: 40 parts of the thermosensitive color-changing color-memory microcapsule pigment obtained as described above were mixed with 50 parts of ethylene-vinyl acetate emulsion, 1 part of defoamer, 1 part of leveling agent, and 8 parts of water. The ink uniformly dispersed in the portion is solid-printed on white high-quality paper having a brightness value of 9.2 using a 180-mesh screen stencil, completely dried, and a thermochromic color having a coating thickness of 20 μm. A printed material using the memory microcapsule pigment was obtained. The obtained printed matter was heated and cooled by the following method, and the discoloration behavior was plotted on a graph. The printed matter is adhered to a predetermined portion of a color difference meter (TC-3600 type color difference meter, manufactured by Tokyo Denshoku Co., Ltd.), and the portion is placed within a temperature range of 70 ° C.
The printed matter was heated and cooled at a rate of 0 ° C./min. For example, in the case of Example 1, heating was performed at a rate of 10 ° C./min to 60 ° C. with -10 ° C. as a measurement start temperature, and then cooled again to −10 ° C. at a rate of 10 ° C./min. At each temperature, the lightness value displayed on the color difference meter is plotted on a graph to create a discoloration curve illustrated in FIG.
₁ , T ₂ , T ₃ , T ₄ , T _H (the midpoint temperature of the color density in the coloring process), T _G (the midpoint temperature of the color density in the decoloring process), and ΔH (the line segment HG) Each value was obtained.

Method for Measuring Contrast At the time of measuring the hysteresis characteristic, for example, the embodiment 10
For the color difference meter lightness value V _E when the -10 ° C. [TC-
3600 color difference meter, manufactured by Tokyo Denshoku Co., Ltd.]
Next, read in the same way the brightness value V _F when the 60 ° C.,
The contrast ΔV was calculated as V _F -V _E.

Examples 13 to 19 Hysteresis characteristics were measured in the same manner as in Example 12.
The component (c) applied to the production of the thermochromic color-memory microcapsule pigment, and T ₁ , T ₂ , T ₃ , T ₄ ,
_TH (temperature at the midpoint of color density in the coloring process), T
_G (temperature at the midpoint in color density in the decoloring process), [Delta] H (a line segment _{HG), V E, V F} , the values of ΔV (V _F -V _E) shown in Table 2. The component (c) is as shown in Table 2, and the components (a) and (b) and other samples and their parts by weight are the same as in Example 12.

[Table 2]

Example 20 (a) As an electron-donating color-forming organic compound, 3.0 parts of 6- (ethylisobutylamino) benzo-α-fluoran,
(B) As a phenol compound, 8.0 parts of 2,2-bis (4-hydroxyphenyl) propane and (c) 50.0 parts of n-laurophenone were microencapsulated by the same method, and the color was changed from pink to colorless. A changing thermochromic color memory microcapsule pigment was obtained.

Example 21 (a) As an electron-donating color-forming organic compound, 3- (4-
Diethylamino-2-ethoxyphenyl) -3- (1-
1.5 parts of ethyl-2-methylindol-3-yl) -4-azoazophthalide, 8.0 parts of 2,2-bis (4-hydroxyphenyl) propane as (b) phenol compound, (c) n- Laurophenone (50.0 parts) was microencapsulated by the same method to obtain a thermosensitive color-changeable color memory microcapsule pigment that changes from blue to colorless.

In the same manner as in Example 12, the thermochromic color-storing microcapsule pigments obtained in Examples 20 and 21 were read for their color change characteristics and lightness value, and the contrast ΔV was determined as V _F -V _E. It was calculated as Table 3 shows each value.
Shown in

[Table 3]

Application Example 1 (a) 3-dibutylamino-6-methyl-7-anilinofluoran, (b) 1,1-bis (4-hydroxyphenyl) -3-methylbutane, (c) n-lauro The three-component homogeneous solution of phenone was microencapsulated by an epoxy resin / amine interfacial polymerization method, and the average particle diameter was 10%.
A μm thermochromic color-memory microcapsule pigment was obtained. The obtained thermosensitive color-changeable color memory microcapsule pigment has a black-colorless reversible thermochromic property (T ₁ : −6 ° C., T
₄ : 46 ° C). Ethylene containing the thermosensitive color-changing color memory microcapsule pigment on the surface of white fine paper
The ink dispersed in the vinyl acetate emulsion was printed using a screen plate (180 mesh) to prepare a thermochromic recording paper. The recording paper is visually made black in a normal state, and becomes white by heating at 46 ° C. or more. This state is maintained at a room temperature of about 25 ° C. Next, when cooled to -6 ° C. or lower, the color became black, and this state was maintained at room temperature. Either the black or white state of the recording paper could be maintained alternately in the normal temperature range. Heating pen (55 ° C) on the recording paper in black state at room temperature
When I wrote with, white handwriting was visible. On the other hand, when writing on the recording paper in a white state with a cold and hot pen (-10 ° C.), black handwriting appeared. This state was maintained at the room temperature.

Application Example 2 (a) 3-dibutylamino-6-methyl-7-anilinofluoran, (b) 1,1-bis (4-hydroxyphenyl) -3-methylbutane, (c) n-decanophenone The three-component homogeneous solution is microencapsulated by an epoxy resin / amine interfacial polymerization method to obtain an average particle size of 10
A μm thermochromic color-memory microcapsule pigment was obtained. The resulting thermosensitive color-changeable color memory microcapsule pigment has a black-colorless reversible thermochromic property (T ₁ : −23 ° C.,
T ₄ : 36 ° C). 40 parts of the obtained thermochromic color-storing microcapsule pigment containing acrylic acid emulsion as a main component was uniformly dispersed in 60 parts of a colorless and transparent aqueous screen ink vehicle, and using a 109-mesh screen plate, Printing was performed in vivid chromatic colors of pink, blue and yellow on a printed material having a polka dot pattern drawn on white high-quality paper to obtain a thermochromic color memory print. The printed matter had a black color at room temperature of about 20 ° C., and the colorful polka dot pattern drawn on the base could not be seen at all, and was completely hidden by the black color.
By heating at 6 ° C. or more, the black color was erased, and bright pink, blue, and yellow polka dots appeared. This state is maintained at a room temperature of about 20 ° C., and then when cooled to −23 ° C. or less, it becomes black again, and the vivid polka dots of pink, blue and yellow are completely hidden and cannot be visually recognized. Was.

Comparative Examples 1 to 5 (a) As an electron-donating color-forming organic compound, 3-dibutylamino-6-methyl-7-anilinofluoran 3.0
Parts, (b) 8.0 parts of 2,2-bis (4′-hydroxyphenyl) propane as a phenol compound,
(C) a known ester compound having a color memory property;
0 parts of the three components were heated and dissolved at 120 ° C. to form a homogeneous solution, and Epon 828 [Yuka Kasper Epoxy Co., Ltd.]
Manufactured by Epoxy Resin Co., Ltd.) and 10 parts of methyl ethyl ketone, and the resulting mixture is dropped into 100 parts of a 10% aqueous gelatin solution and stirred to form fine droplets. A solution prepared by dissolving 5 parts of a separately prepared curing agent Epicure U (an amine adduct of an epoxy resin manufactured by Yuka Shell Epoxy Co., Ltd.) in 45 parts of water was gradually added to the stirring solution, Stirring was continued for about 5 hours while maintaining the liquid temperature at 80 ° C. to obtain a stock solution of microcapsules. By centrifuging the undiluted solution, a thermochromic color-memory microcapsule pigment having a water content of about 40% by weight and changing from black to colorless can be obtained. The discoloration characteristic and the brightness value are read, and the contrast ΔV is set to V _F −
It was calculated as V _E. Table 4 shows the values.

[Table 4]

Comparative Example 6 (a) As an electron-donating color-forming organic compound, 3.0 parts of 6- (ethylisobutylamino) benzo-α-fluoran,
(B) As a phenol compound, 8.0 parts of 2,2-bis (4-hydroxyphenyl) propane and (c) 50.0 parts of n-heptyl stearate are microencapsulated by the same method, and pink to colorless. A thermosensitive color-changeable color-memory microcapsule pigment which changes to Comparative Example 7 (a) As the electron-donating color-forming organic compound, 3- (4-
Diethylamino-2-ethoxyphenyl) -3- (1-
1.5 parts of ethyl-2-methylindol-3-yl) -4-azoazophthalide, 8.0 parts of 2,2-bis (4-hydroxyphenyl) propane as a (b) phenol compound, and (c) stearic acid 50.0 parts of n-heptyl were microencapsulated in the same manner to obtain a thermochromic color-memory microcapsule pigment that changes from blue to colorless.

In the same manner as in Example 12, the thermochromic color-storing microcapsule pigments obtained in Comparative Examples 6 and 7 were read for their color change characteristics and lightness value, and the contrast ΔV was determined as V _F -V _E. It was calculated as Table 5 shows each value.

[Table 5]

[0029]

The thermochromic color-memory composition of the present invention, particularly the microencapsulated pigment, exhibits a hysteresis width (.DELTA.H) of 8 DEG C. to 80 DEG C. with respect to the color density-temperature curve and develops and decolors. It causes reversible discoloration of the color, and both the color lower than the color change temperature and the color higher than the color change temperature can be stored alternately in the normal temperature range, and by applying heat or cold as necessary, The color can be reversibly reproduced and the characteristics that can be stored and stored can be effectively developed.Furthermore, a very high contrast can be developed due to the high density at the time of color development and the good color disappearance at the time of color erasing. it can. The thermochromic color memory composition of the present invention, particularly the microencapsulated pigment, can be used as a paint or printing ink for various coatings or printed matter, or the pigment can be melted in a thermoplastic resin or wax. It is blended and applied as various forms of excipients.

[Brief description of the drawings]

FIG. 1 shows the color density of the thermochromic color memory composition of the present invention.
5 is a graph illustrating a hysteresis characteristic in a temperature curve.

[Explanation of symbols]

T ₁ full colored temperature T ₂ minimum holding temperature T ₃ maximum holding temperature T ₄ complete decoloring temperature

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B41M 5/28-5/34 C09B 67/02 C09D 11/02 C09K 9/02

Claims (3)

(57) [Claims] (1) an electron-donating color-forming organic compound,
(B) an electron-accepting compound selected from compounds having a phenolic hydroxyl group ; (c) an arylalkyl ketone having a total carbon number of 12 to 24 for controlling the color reaction of the above (a) and (b) consisting homogeneous phase solution of the ternary compound selected from the class as an essential component, color density - related <br/> to the temperature curve, colored with cooling, it becomes colorless when heated co
A thermochromic color memory composition that exhibits a hysteresis width (ΔH) of 8 ° C. to 80 ° C. and changes color. 2. The method according to claim 1, wherein the arylalkyl ketone is a compound selected from phenylalkyl ketones.
The thermochromic color memory composition according to the above. 3. A thermochromic color memory microcapsule pigment comprising the thermochromic color memory composition according to claim 1 in a microcapsule.