JP3396787B2 - Thermochromic color memory microcapsule pigment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermochromic color-storing microcapsule pigment. 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-memory microcapsule pigment which maintains the temperature in a room temperature range in an alternating and reversible manner. [0002] The present applicant has previously proposed a thermochromic color memory material of this kind (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 a compound selected from esters which control a color reaction as disclosed in Japanese Patent Publication No. 4-17154. Of these, the thermochromic effect can be expressed only by a system in which a specific compound is applied as a constituent component, so the utilization of this type of thermochromic material is restricted,
The discovery of new effective compounds has been awaited. The present inventors have further pursued a compound serving as a reaction medium for exhibiting the color memory effect, increasing the degree of freedom of selection of the reaction medium, and further having a high density at the time of color development and a good color erasure at the time of color erasure. The use of this kind of thermochromic color memory material is intended to be further enhanced by the extremely high contrast of the present invention. SUMMARY OF THE INVENTION The present inventors have developed a system in which a compound selected from fatty acid ketones having a total carbon number of 14 to 22 is used as a reaction medium for a color reaction. The present inventors have found that a thermochromic property having a large (ΔH) is exhibited, an effective color memory effect is exhibited, and a very high contrast is obtained due to a high density at the time of color development and a good color erasure at the time of color erasing. Completed the invention. The present invention relates to (a) an electron-donating color-forming organic compound, (b) a compound having a phenolic hydroxyl group as the electron-accepting compound ,
(C) A microcapsule encloses a homogeneous compatibilizing solution containing three components of a compound selected from aliphatic ketones having a total carbon number of 14 to 22 for controlling the color reaction of (a) and (b) as essential components. As for the color density-temperature curve,
A thermosensitive color-changeable color memory microcapsule pigment which exhibits a hysteresis width (ΔH) of from 30 ° C. to 30 ° C. and discolors is required. The hysteresis characteristic of the thermochromic color-storing microcapsule pigment of the present invention in a color density-temperature curve will be described with reference to the graph of FIG. 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 a coloring / erasing branching temperature) at which the color is completely erased, and B
Is a point indicating a density at a maximum temperature T ₃ (hereinafter, referred to as a maximum holding temperature) at which a completely colored state can be maintained, and C is a minimum temperature T ₂ (hereinafter, referred to as a minimum holding temperature) at which a completely decolored state can be maintained. ), And D is a point indicating the density at the maximum temperature T ₁ (hereinafter, referred to as a complete coloration temperature) at which a complete coloration state is reached. At the temperature T _A , the two phases of the colored state E point and the decolored state F point coexist. The temperature range including the temperature T _A where the coloration state and the decoloration state can coexist is the temperature range in which the color change can be maintained, and the line segment EF
Is a measure of the contrast of the discoloration, and the line segment E
The length of the line segment HG passing through the middle point of F is a temperature width indicating the degree of hysteresis (hereinafter, referred to as hysteresis width ΔH), and the greater the ΔH value, the easier it is to maintain each state before and after discoloration. . According to the experiments of the present inventors, the ΔH value that can be maintained before and after practical discoloration is in the range of 8 ° C. to 30 ° C. Further, in the above, the two phases of the colored state and the decolored state are substantially maintained and the temperature for practical use, that is, the temperature range between T ₃ and T ₂ including T _A is 2 ° C. or more and 30 ° C. or more. A range below ℃ is effective. 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 density difference 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.
Dissolution aids and 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,
Examples include diphenylmethane azaphthalides, indolyl phthalides, phenyl indolyl phthalides, phenyl indolyl azaphthalides, styrylquinolines, 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-ethoxyphenyl) -3-
(1-ethyl-2-methylindol-3-yl) -4
-Azaphthalide, 1,3-dimethyl-6-diethylaminofluoran, 2-chloro-3-methyl-6-dimethylaminofluoran, 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, 1,2-benz-6 -Ethylisoamylaminofluoran, 2-methyl-6- (Np-tolyl-N-ethylamino) fluoran, 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
-Dodecoxystyrylquinoline and the like. Used as an electron-accepting compound of the component (b)
Examples of the compound having a phenol hydroxyl group to be, 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 an ester or amide group, a halogen group, etc. 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-butylcatechol, 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, 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, 1,1-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. Next, the total carbon number of the component (c) is 14 to 22.
Specific examples of the aliphatic ketones are shown below.
2-tetradecanone, 2-pentadecanone, 8-pentadecanone, 2-hexadecanone, 3-hexadecanone,
9-heptadecanone, 2-pentadecanone, 2-octadecanone, 2-nonadecanone, 10-nonadecanone, 2
-Eicosanone, 11-heneicosanone, 2-heneicosanone, 2-docosanone, and the like. As the component (C) of the present invention, the above-mentioned aliphatic ketones are used. If necessary, other esters, alcohols, carboxylic acids, amides and the like can be added as long as the hysteresis characteristics are not largely changed. In this case, the addition amount is preferably 50 parts or less (parts by weight) with respect to 50 parts of the aliphatic 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 of (a), (b) and (c) is encapsulated in microcapsules by a known microencapsulation technique. Fine particles (0.
5 to 50 μm, preferably 1 to 30 μm), it is possible to impart a property having a large ΔH value as compared with the non-particulate state,
By being protected by the capsule membrane wall, acidic substances,
Even if it comes into contact with a chemically active substance such as a basic substance or a peroxide or other solvent components, its function is not reduced, and heat resistance stability can be maintained. Available microencapsulation techniques include interfacial polymerization and in situ
u polymerization method, liquid curing coating method, phase separation method from aqueous solution, phase separation method from organic solvent, melt dispersion cooling method, air suspension coating method, spray drying method, etc. Selected. 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. According to the present invention, a compound selected from the aliphatic ketones according to the present invention is blended as a reaction medium for a color reaction by electron transfer, so that a thermal discoloration having a large hysteresis width (ΔH) with respect to a color density-temperature curve is obtained. By expressing the characteristics, furthermore, due to the high density at the time of color development and the goodness of color erasure at the time of decoloration,
It functions as a discolorable composition having a very high contrast (ΔV), and further has a ΔH effective for expressing a color memory effect of 8 by forming the composition into a fine particle form by encapsulating the composition in a microcapsule. A hysteresis characteristic of 30 ° C. to 30 ° C. can be exhibited. Although the theoretical elucidation of the action is still inadequate, for high contrast,
It is presumed that the aliphatic ketone compound of the present invention has a smaller total carbon number and an increased polarizability at the same melting point than the ester compound, as compared with the ester compound. The thermochromic behavior is repeatedly reproduced as shown in the measurement data of thermochromic characteristics in Examples described later. Examples 1 to 7 Examples of the present invention are shown below, but the present invention is not limited to these examples. The method for producing the thermosensitive color-changeable color memory microcapsule pigment, the method for measuring the hysteresis characteristics of the microcapsule pigment according to the temperature change, and the method for measuring the contrast in each of the examples will be described below. Parts in the following formulation examples indicate parts by weight. 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 is used.
Part, as a (b) phenol compound, 2,2-bis (4
-Hydroxyphenyl) propane (8.0 parts), and (c) 30.0 parts of the aliphatic ketone compound of the present invention,
The mixture was heated and melted at 20 ° C. to form a homogeneous solution.
8 [Yuika Shell Epoxy Co., Ltd., epoxy resin] 10
Parts and a mixed solution of 10 parts of methyl ethyl ketone and then added dropwise to 100 parts of a 10% aqueous gelatin solution.
Stir so as to be 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 stock solution, a thermochromic color-memory microcapsule pigment having a water content of about 40% by weight and changing from black to colorless was obtained. Method for measuring hysteresis characteristics 40 parts of the thermosensitive color-changeable color-memory microcapsule pigment obtained as described above were mixed with 50 parts of an ethylene-vinyl acetate emulsion, 1 part of an antifoaming agent, 1 part of a 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 print of 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 was measured using a colorimeter [TC-3
600 type color difference meter, manufactured by Tokyo Denshoku Co., Ltd.], and the portion is 10 ° C./mi within a temperature range of 50 ° C.
The print was heated and cooled at a speed of n . 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, and T ₁ , T ₂ , T ₃ , T
₄ , _TH (temperature at the midpoint of color density in the coloring process), T
_G (the temperature at the midpoint of the color density in the decoloring process) and ΔH
(Line segment HG) were obtained. [0017] the measurement of the measuring method the hysteresis characteristics of contrast, color difference meter Lightness value V _E [TC-3600 type color difference meter, Ltd. Tokyo Electric Ltd. color] read from, then the bright degree value V _F reading was similarly calculated contrast ΔV as V _F -V _E. The component (c) applied to the production of the thermochromic color-memory microcapsule pigment, and T ₁ , T ₂ , T ₃ , T ₄ , T _H (the temperature at the midpoint of the color density in the coloring process), T Table 1 shows values of _G (the temperature at the midpoint of the color density in the decoloring process) and ΔH (line segment HG). [Table 1] Example 8 Preparation of thermosensitive color-changeable color-memory microcapsule pigment (a) As an electron-donating color-forming organic compound, 3.0 parts of 6- (ethylisobutylamino) benzo-α-fluoran,
(B) As a phenol compound, three components consisting of 8.0 parts of 2,2-bis (4-hydroxyphenyl) propane and (c) 50.0 parts of 8-pentadecanone were heated and dissolved at 120 ° C. to obtain a homogeneous phase. The mixture was mixed with 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.
The solution is dropped into 100 parts of a 0% gelatin aqueous solution, and the mixture is stirred to form fine droplets. Separately prepared 5 parts of curing agent EpiCure U
A solution prepared by dissolving [amine adduct of epoxy resin manufactured by Yuka Shell Epoxy Co., Ltd.] in 45 parts of water was gradually added to the stirring solution, and the solution temperature was maintained at 80 ° C. for about 5 hours. Stirring was continued for an hour to obtain a stock solution of microcapsules. By centrifuging the stock solution, a thermochromic color-memory microcapsule pigment having a water content of about 40% by weight and changing from pink to colorless was obtained. Example 9 Preparation of thermosensitive color-changeable color memory microcapsule pigment (a) As an electron-donating color-forming organic compound, 3- (4-
Diethylamino-2-ethoxyphenyl) -3- (1-
1.5 parts of ethyl-2-methylindolyl-3-yl) -4-azoazophthalide, (b) 8.0 parts of 2,2-bis (4-hydroxyphenyl) propane as a phenol compound, and (c) 8- From the three components consisting of 50.0 parts of pentadecanone, a thermochromic color-memory microcapsule pigment that changes from blue to colorless was obtained in the same manner as in Example 11 above. Using a 180-mesh screen plate on white high-quality paper having a lightness value of 9.2, 40 parts of the obtained thermochromic color-storing microcapsule pigment were respectively mixed and treated in the same manner and in the same manner as in Examples 1 to 7. The printed matter is screen-printed, and its discoloration characteristics and lightness value are read using the color difference meter used in Examples 1 to 7 , and the contrast ΔV is converted to V _F.
It was calculated as -V _E. Table 2 shows the values. [Table 2] 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 subjecting the undiluted solution to a centrifugation treatment, a thermosensitive color-changing color memory microcapsule pigment having a water content of about 40% by weight and changing from black to colorless can be obtained, in the same manner as in Examples 1 to 7 . , Its discoloration characteristics and lightness value are read, and the contrast ΔV is set to V _F
It was calculated as -V _E. Table 3 shows the values. [Table 3] Comparative Example 6 (a) As an electron-donating color-forming organic compound, 3.0 parts of 6- (ethylisobutylamino) benzo-α-fluorane,
(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 by the same method to obtain a thermochromic color memory pigment that changes from blue to colorless. The thermochromic color-storing microcapsule pigments obtained in Comparative Examples 6 and 7 were read in the same manner as in Examples 8 and 9 for their color change characteristics and lightness value, and the contrast ΔV was determined as V _F − It was calculated as V _E. Table 4 shows each value.
Shown in [Table 4] Application Example 1 (a) 3-dibutylamino-6-methyl-7-anilinofluoran, (b) 1,1-bis (4-hydroxyphenyl) -3-methylbutane, (c) 8-pentadecanone 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 obtained thermosensitive color-changeable color memory microcapsule pigment has a black-colorless reversible thermochromic property (T ₁ : 7 ° C., T
₄ : 39 ° 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 40 ° C. or more. This state is maintained at a room temperature of about 25 ° C. Next, when the temperature was cooled to about 7 ° 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 (0 ° 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) 2-Pentadecanone 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 obtained thermosensitive color-changeable color memory microcapsule pigment has a black-colorless reversible thermochromic property (T ₁ : 8 ° C., T
₄ : 39 ° 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 is normally visible in black, and the colorful polka dots drawn on the base were completely invisible by black, but were completely concealed by black. Disappeared, and bright pink, blue and yellow polka dots appeared. This state is maintained at a room temperature of about 25 ° C., and then cooled to about 8 ° C. or less, the color turns black again, and the vivid polka dots of pink, blue and yellow are completely concealed and can be visually observed. lost. Either the black state or the chromatic pattern state of the printed matter can be maintained alternately in a normal temperature range. When writing on the recording paper which is in a black state at room temperature with a heating pen (55 ° C.), the printed state is obtained. Colorful and vivid handwriting of color was visually recognized. On the other hand, when the printed matter in a vivid chromatic polka dot state was written with a cold / hot pen (0 ° C.), black handwriting appeared. This state was maintained at the room temperature. The thermosensitive color-changing color memory microcapsule pigment of the present invention has a color density-temperature curve of from 8 ° C. to 30 ° C.
It shows a hysteresis width (.DELTA.H) of .degree. C. to cause reversible discoloration of color development-decoloration, and can store and store both colors on the lower side and higher side of the discoloration temperature in a normal temperature range. By applying heat or cold as appropriate, it is possible to effectively develop the characteristic that any color can be reversibly reproduced and stored, and furthermore, high density at the time of color development and color disappearance at the time of color erasure , A very high contrast can be developed. The thermochromic color-memory microcapsule pigment of the present invention can be applied to various coatings or printed materials as paints or printing inks, or melt-blended with pigments such as thermoplastic resins and waxes to form various forms. Applied as an excipient.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph illustrating a hysteresis characteristic in a color density-temperature curve of the thermosensitive color-changing color memory microcapsule pigment of the present invention. [EXPLANATION OF SYMBOLS] T ₁ fully colored temperature T ₂ minimum holding temperature T ₃ maximum holding temperature T ₄ coloring and decoloring properties branched Temperature

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-68880 (JP, A) JP-A-61-53388 (JP, A) JP-A-59-120492 (JP, A) 11242 (JP, A) JP-A-4-17154 (JP, A) JP-A-60-264285 (JP, A) JP-A-3-76786 (JP, A) JP-A-6-135144 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C09B 67/00 C09K 9/00 B41M 5/00

Claims (1)

(57) [Claims] (1) (a) an electron-donating color-forming organic compound,
(B) having a phenolic hydroxyl group as an electron-accepting compound;
Compounds, (c) said (a), fine and homogeneous phase solution the total number of carbon atoms for controlling the color reaction as an essential component a ternary compound selected from aliphatic ketones of 14 to 22 (b) A thermosensitive color-changing color memory microcapsule pigment which is encapsulated and discolors with a hysteresis width (ΔH) of 8 ° C to 30 ° C with respect to a color density-temperature curve.