JP2020063320A - Reversible thermochromic aqueous ink composition for ink jet printer - Google Patents

Abstract

To provide a reversible thermochromic aqueous ink composition for an ink jet printer, which can form a highly precise reversible thermochromic printed image rich in color developability.SOLUTION: A reversible thermochromic aqueous ink composition for an ink jet printer, which is characterized by that it contains water, (a) an electron donating color development organic compound, (b) an electron receiving compound, and (c) a reversible thermochromic micro capsule pigment including a reversible thermochromic composition made of a reactive medium that determines an origination temperature of a color development reaction between (a) and (b), a volume average particle size of the microcapsule pigment is 0.1 to 5 μm, and the microcapsule pigment having the volume average particle size does not contain microcapsule pigment particles having a particle size exceeding 8 μm.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a reversible thermochromic ink composition for inkjet printers. More specifically, the present invention relates to a reversible thermochromic water-based ink composition for an inkjet printer, which is excellent in color development and capable of forming a high-definition reversible thermochromic printed image. The present invention also relates to an ink container using the water-based ink composition, and an ink jet printer containing the water-based ink composition.

  In general, an inkjet printer forms a desired image on a recording medium by ejecting ink supplied from an ink container to the printer head onto a recording medium from nozzles of the printer head. Ink is supplied from the ink container to the printer head via the tube. The ink is supplied by using a pump, and when the image is not being formed, the pump is stopped to keep the printer head and the tube filled with the ink.

  In recent years, as a part of ecology, specifications that enable reuse of printing paper are being sought, and as an example of fulfilling such a request, reversible thermochromic microcapsules that can erase a printed image by heating. Ink jet printing inks using pigments have been proposed. (For example, see Patent Document 1)

  The above-mentioned conventional technique includes a reversible thermochromic microcapsule pigment (hereinafter referred to as a microcapsule pigment) containing a leuco dye, a color developer, and a decoloring agent, and a solvent, and develops a color at room temperature (under 25 ° C). It is an ink capable of erasing a printed image by heating the printed image to 55 ° C. or higher.

  However, in an ink containing a colorant insoluble in an ink solvent such as a microcapsule pigment, the colorant tends to form an aggregate with time in a stationary state. However, even if the colorant is supplied to the toner, the density of the colorant is not uniform, so that the quality of the formed image is deteriorated and the variation of the image quality is sometimes increased. In addition, the nozzle of the printer head may be clogged with the colorant that has aggregated and precipitated.

In order to solve the above problems, there has been proposed an inkjet printing printer apparatus capable of preventing ink from staying and suppressing aggregation of a colorant to prevent clogging of nozzles of a printer head. (For example, see Patent Document 2)
According to this apparatus, the ink in the ink flow path is circulated, and the ink is constantly ejected from the printer head at a predetermined pressure. It is possible to prevent the nozzles of the printer head from clogging by suppressing agglomeration in the flow path and the printer head.

Certainly, the above-mentioned device allows the aggregation of the colorant to be suppressed to some extent even when the colorant insoluble in the solvent is used. However, when a microcapsule pigment is used as the colorant, the microcapsule pigment has a larger particle size than general pigments, and therefore, depending on the particle size, clogging at the nozzle of the printer head may occur even with the above device. May occur. Further, when a microcapsule pigment having an excessively small particle size is used, clogging can be suppressed, but the coloring power of the microcapsule pigment is low, so that there is a problem that the coloring property of a printed image is deteriorated.
Furthermore, even if the microcapsule pigment has a particle size that does not cause clogging and has sufficient coloring power, the nozzles of the printer head may be evenly ejected depending on the variation in the particle size. Since it is difficult to form ink droplets having a diameter, the ink ejection becomes unstable, and the landing accuracy of the ink droplets on the surface to be printed decreases, which may make it difficult to form a high-definition printed image.

Japanese Patent No. 5634225 Japanese Utility Model Publication No. 54-18919

  The present invention has been made in view of the above, when forming a printed image by an inkjet printer, the ink flow path, and the nozzle of the printer head is not clogged with the reversible thermochromic capsule pigment, the ink is well A reversible thermochromic water-based ink composition for an ink jet printer and an ink container using the water-based ink composition, which discharges and is capable of forming a high-definition reversible thermochromic printed image that is rich in color developability, and the water-based ink composition. An inkjet printer containing an ink composition is provided.

The present invention, in order to solve the above problems,
“1. Ink storage unit, printer head, ink supply channel for supplying ink from the ink storage unit to the printer head, and ink not ejected from nozzles of the printer head is returned from the printer head to the ink supply channel. An ink composition housed in an ink jet printer that includes an ink recovery channel, circulates ink through the ink supply channel, the printer head, and the ink recovery channel, and includes water and (a) electron donation. Thermochromic microcapsule pigment containing a reversible thermochromic composition comprising a color-changing organic compound, (b) an electron-accepting compound, and (c) a reaction medium that determines the temperature at which the color reaction of both of them occurs. Wherein the microcapsule pigment has a volume average particle size of 0.1 to 5 μm and a particle size of more than 8 μm. A reversible thermochromic water-based ink composition for inkjet printers, which is characterized by not containing cell pigment particles.
2. Ink storage unit, printer head, ink supply channel for supplying ink from the ink storage unit to the printer head, and ink for returning ink not ejected from the nozzles of the printer head from the printer head to the ink supply channel An ink composition housed in an ink jet printer having a recovery flow path, which circulates ink through the ink supply flow path, the printer head, and the ink recovery flow path, wherein water and (a) electron donating property A reversible thermochromic microcapsule pigment containing a reversible thermochromic composition comprising a color-developing organic compound, (b) an electron-accepting compound, and (c) a reaction medium that determines the temperature at which the color reaction of both of them occurs. , A dispersant, wherein the microcapsule pigment has a positive or negative zeta value in a liquid containing water and the microcapsule pigment. Reversible thermochromic aqueous ink composition for inkjet printer, characterized in that the dispersant has a functional group having a charge having a sign opposite to the value of the zeta potential of the microcapsule pigment in the structure. object.
3. An ink container containing the water-based ink composition according to item 1 or 2.
4. An ink container set comprising a plurality of ink containers according to item 3.
5. The ink containing portion containing the water-based ink composition according to claim 1 or 2, a printer head, an ink supply channel for supplying ink from the ink containing portion to the printer head, and a nozzle of the printer head. An ink jet printer comprising an ink recovery flow path for returning the ink that has not existed from the printer head to the ink supply flow path, and circulating ink through the ink supply flow path, the printer head, and the ink recovery flow path.
6. The ink jet printer according to item 5, wherein the printer head includes a flow path for circulating ink in the printer head.

  According to the present invention, when a printed image is formed by an inkjet printer, the ink flow path and the nozzle of the printer head do not cause clogging with the reversible thermochromic capsule pigment, and the ink has excellent coloring power and a uniform diameter. Liquid droplets are ejected well from the nozzle, and the surface to be printed is not only flat such as paper and film, but also three-dimensional objects with curved surfaces, rich in color development and high-definition reversible thermochromism There is provided a reversible thermochromic water-based ink composition for an ink-jet printer, an ink container using the water-based ink composition, and an ink-jet printer containing the water-based ink composition, which are capable of forming a printed image.

It is explanatory drawing which shows the color change behavior of the microcapsule pigment (heat-decoloring type) which included the reversible thermochromic composition. It is explanatory drawing which shows the discoloration behavior of the microcapsule pigment (heat-decoloring type) which encapsulated the reversible thermochromic composition which has color memory. It is a schematic diagram showing an example of composition of an ink jet printer.

  Hereinafter, embodiments of the present invention will be described in detail. In the present specification, “parts”, “%”, “ratio”, etc. indicating the composition are based on mass unless otherwise specified.

  The reversible thermochromic water-based ink composition for an ink jet printer according to the present invention (hereinafter, sometimes referred to as “water-based ink composition” or “ink composition”) comprises water and reversible thermochromic microcapsules. And at least a pigment. Hereinafter, each component constituting the water-based ink composition according to the present invention will be described.

(Reversible thermochromic microcapsule pigment)
The aqueous ink composition of the present invention contains a reversible thermochromic microcapsule pigment.
A reversible thermochromic microcapsule pigment (hereinafter also simply referred to as "microcapsule pigment") is a reversible medium composed of an electron-donating color-forming organic compound, an electron-accepting compound, and a reaction medium that determines the temperature at which the color reaction between the two occurs. It contains a thermochromic composition.

  As the microcapsule pigment, a color change occurs before and after a predetermined temperature (color change point) as a boundary, which is described in JP-B-51-44706, JP-B-51-44707, and JP-B-1-29398. However, it exhibits a decolored state in a temperature range above the high-temperature side discoloration point, and a colored state in a temperature range below the low-temperature side discoloration point, and only one specific state exists in the normal temperature range of the above two states, and the other one The state is maintained as long as the heat or cold required to develop the state is applied, but returns to the state exhibited at room temperature when the heat or cold is no longer applied, and the hysteresis width is relatively small. A microcapsule pigment containing a heat-decolorable reversible thermochromic composition having characteristics (ΔH = 1 ° C. to 7 ° C.) can be used (see FIG. 1).

  Further, a reversible thermochromic composition exhibiting a large hysteresis characteristic, which is described in JP-A-2006-137886, JP-A-2006-188660, JP-A-2008-45062, JP-A-2008-280523 and the like. It is also possible to use a microcapsule pigment containing a substance. That is, the shape of the curve plotting the change in the coloring density due to the temperature change is significantly different between the case where the temperature is increased from the lower temperature side than the color change temperature range and the case where the temperature is decreased from the higher temperature side than the color change temperature range. The color changes along the route, and the color development state in the low temperature range below the complete color development temperature (t1) or the color removal state in the high temperature range above the complete color removal temperature (t4) is in the specific temperature range [between t2 and t3. In the temperature range (substantially two-phase holding temperature range)], a microcapsule pigment including a reversible thermochromic composition having color memory can be used (see FIG. 2).

The hysteresis characteristic in the color density-temperature curve of the microcapsule pigment containing the reversible thermochromic composition having color memory will be described.
In FIG. 2, the vertical axis represents color density and the horizontal axis represents temperature. The change in color density due to the temperature change progresses along the arrow. Here, A is a point indicating the density at a temperature t4 (hereinafter referred to as a complete erasing temperature) at which the completely erasing state is reached, and B is a temperature t3 at which the erasing is started (hereinafter referred to as an erasing starting temperature). Is a point showing the density at C, C is a point showing the density at a temperature t2 at which color development starts (hereinafter, referred to as a color development start temperature), and D is a temperature t1 at which a fully developed state is reached (hereinafter referred to as a complete color development temperature). ) Is a point indicating the concentration.
The color change temperature range is the temperature range between t1 and t4, and both the colored state and the decolored state can coexist, and the temperature range between t2 and t3, which is a region with a large difference in color density, is the substantial color change temperature range. Is.
Further, the length of the line segment EF is a scale showing the contrast of discoloration, and the length of the line segment HG passing through the midpoint of the line segment EF is a temperature width (hereinafter referred to as hysteresis width ΔH) showing the degree of hysteresis. However, if this ΔH value is small, only one specific state can exist in the normal temperature range of both states before and after discoloration. Further, if the ΔH value is large, it becomes easy to maintain each state before and after the color change.

  The complete erasing temperature t4 is, for example, 50 ° C. or more and 90 ° C. or less, preferably 55 ° C. or more and 85 ° C. or less, and more preferably when erasing the color by frictional heat generated by rubbing between the friction member and the writing surface. Is in the range of 60 ° C. or higher and 80 ° C. or lower, and the complete color development temperature t1 can be a temperature that can be obtained only in a freezer, a cold region, etc., and is, for example, 0 ° C. or lower, preferably −50 ° C. or higher − It is 5 ° C or lower, and more preferably in the range of -50 ° C or higher and -10 ° C or lower.

  The electron-donating color developing organic compound, the electron-accepting compound and the reaction medium will be described below. The electron-donating color-developing organic compound is a component that determines the color tone and is a compound that develops a color by donating an electron to the electron-accepting compound. Examples of the electron-donating color-developing organic compound include a phthalide compound, a fluoran compound, a styrinoquinoline compound, a diazarhodamine lactone compound, a pyridine compound, a quinazoline compound, and a bisquinazoline compound. Of these, a phthalide compound and a fluoran compound are included. At least one selected from the group is preferred.

  Examples of the phthalide compound include diphenylmethanephthalide compound, phenylindolylphthalide compound, indolylphthalide compound, diphenylmethaneazaphthalide compound, phenylindolylazaphthalide compound, and derivatives thereof, and the like. Of these, phenylindolyl azaphthalide compounds and their derivatives are preferable. Examples of the fluoran compound include aminofluorane compounds, alkoxyfluorane compounds, and derivatives thereof.

Examples of these compounds are shown below.
3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide,
3- (4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) phthalide,
3,3-bis (1-n-butyl-2-methylindol-3-yl) phthalide,
3,3-bis (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide,
3- (2-ethoxy-4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide,
3- (2-hexyloxy-4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide,
3- [2-ethoxy-4- (N-ethylanilino) phenyl] -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide,
3- (2-acetamido-4-diethylaminophenyl) -3- (1-propylindol-3-yl) -4-azaphthalide
3,6-bis (diphenylamino) fluorane,
3,6-dimethoxyfluorane,
3,6-di-n-butoxyfluorane,
2-methyl-6- (N-ethyl-N-p-tolylamino) fluorane,
3-chloro-6-cyclohexylaminofluorane,
2-methyl-6-cyclohexylaminofluorane,
2- (2-chloroamino) -6-dibutylaminofluorane,
2- (2-chloroanilino) -6-di-n-butylaminofluorane,
2- (3-trifluoromethylanilino) -6-diethylaminofluorane,
2- (3-trifluoromethylanilino) -6-dipentylaminofluorane,
2- (dibenzylamino) -6-diethylaminofluorane,
2- (N-methylanilino) -6- (N-ethyl-N-p-tolylamino) fluorane,
1,3-dimethyl-6-diethylaminofluorane,
2-chloro-3-methyl-6-diethylaminofluorane,
2-anilino-3-methyl-6-diethylaminofluorane,
2-anilino-3-methoxy-6-diethylaminofluorane,
2-anilino-3-methyl-6-di-n-butylaminofluorane,
2-anilino-3-methoxy-6-di-n-butylaminofluorane,
2-xylidino-3-methyl-6-diethylaminofluorane,
2-anilino-3-methyl-6- (N-ethyl-Np-tolylamino) fluorane,
1,2-benz-6-diethylaminofluorane,
1,2-benz-6- (N-ethyl-N-isobutylamino) fluorane,
1,2-benz-6- (N-ethyl-N-isoamylamino) fluorane,
2- (3-methoxy-4-dodecoxystyryl) quinoline,
Spiro [5H- (1) benzopyrano [2,3-d] pyrimidin-5,1 '(3'H) isobenzofuran] -3'-one, 2- (diethylamino) -8- (diethylamino) -4-methyl ,
Spiro [5H- (1) benzopyrano [2,3-d] pyrimidin-5,1 '(3'H) isobenzofuran] -3'-one, 2- (di-n-butylamino) -8- (di -N-butylamino) -4-methyl,
Spiro [5H- (1) benzopyrano [2,3-d] pyrimidin-5,1 '(3'H) isobenzofuran] -3'-one, 2- (di-n-butylamino) -8- (diethylamino) ) -4-methyl,
Spiro [5H- (1) benzopyrano [2,3-d] pyrimidin-5,1 '(3'H) isobenzofuran] -3'-one, 2- (di-n-butylamino) -8- (N -Ethyl-N-i-amylamino) -4-methyl,
Spiro [5H- (1) benzopyrano [2,3-d] pyrimidin-5,1 '(3'H) isobenzofuran] -3'-one, 2- (dibutylamino) -8- (dipentylamino) -4 -Methyl,
4,5,6,7-Tetrachloro-3- [4- (dimethylamino) -2-methoxyphenyl] -3- (1-butyl-2-methyl-1H-indol-3-yl) -1 (3H ) -Isobenzofuranone,
4,5,6,7-Tetrachloro-3- [4- (diethylamino) -2-ethoxyphenyl] -3- (1-ethyl-2-methyl-1H-indol-3-yl) -1 (3H) -Isobenzofuranone,
4,5,6,7-Tetrachloro-3- [4- (diethylamino) -2-ethoxyphenyl] -3- (1-pentyl-2-methyl-1H-indol-3-yl) -1 (3H) -Isobenzofuranone,
4,5,6,7-Tetrachloro-3- [4- (diethylamino) -2-methylphenyl] -3- (1-ethyl-2-methyl-1H-indol-3-yl) -1 (3H) -Isobenzofuranone,
3 ', 6'-bis [phenyl (2-methylphenyl) amino] -spiro [isobenzofuran-1 (3H), 9'-[9H] xanthen] -3-one,
3 ', 6'-bis [phenyl (3-methylphenyl) amino] -spiro [isobenzofuran-1 (3H), 9'-[9H] xanthen] -3-one,
3 ', 6'-bis [phenyl (3-ethylphenyl) amino] -spiro [isobenzofuran-1 (3H), 9'-[9H] xanthen] -3-one,
2,6-bis (2'-ethyloxyphenyl) -4- (4'-dimethylaminophenyl) pyridine,
2,6-bis (2 ′, 4′-diethyloxyphenyl) -4- (4′-dimethylaminophenyl) pyridine,
2- (4'-dimethylaminophenyl) -4-methoxy-quinazoline,
4,4 '-(ethylenedioxy) -bis [2- (4-diethylaminophenyl) quinazoline] and the like can be mentioned.

  As the fluoranes, in addition to the compound having a substituent on the phenyl group forming a xanthene ring, a substituent on the phenyl group forming a lactone ring as well as a substituent on the phenyl group forming a xanthene ring (for example, , An alkyl group such as a methyl group, or a halogen atom such as a chloro group), and a compound exhibiting a blue color or a black color.

  Examples of the electron-accepting compound include compounds having an active proton, pseudo-acidic compounds (a compound which is not an acid but acts as an acid in the composition to develop an electron-donating color-forming organic compound), and an electron vacancy. There is a group of compounds having pores. Examples of the compound having an active proton include compounds having a phenolic hydroxyl group, such as monophenols and polyphenols, and further substituents thereof include an alkyl group, an alkenyl group, an aryl group, an acyl group, an alkoxycarbonyl group, and a carboxy group. Examples thereof include compounds having an ester or amide group thereof, a halogen group, and the like, and phenol-aldehyde condensation resins such as bis type and tris type phenols. Further, it may be a metal salt of a compound having a phenolic hydroxyl group.

  Specific examples of the electron-accepting compound include phenol, o-cresol, tert-butylcatechol, nonylphenol, n-octylphenol, n-dodecylphenol, n-stearylphenol, p-chlorophenol, p-bromophenol, o-phenyl. Phenol, n-butyl p-hydroxybenzoate, n-octyl p-hydroxybenzoate, resorcin, dodecyl gallate, bis (4-hydroxyphenyl) sulfone, bis (4-hydroxyphenyl) sulfide, bis (3-allyl- 4-hydroxyphenyl) sulfone, 4-hydroxyphenyl-4-isopropoxyphenylsulfone, 4-benzyloxyphenyl-4-hydroxyphenylsulfone, 1,1-bis (4-hydroxyphenyl) ethane, 1,1-bis ( -Hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) n-butane, 1,1-bis (4-hydroxyphenyl) n-pentane, 1,1-bis (4-hydroxyphenyl) n-hexane , 1,1-bis (4-hydroxyphenyl) n-heptane, 1,1-bis (4-hydroxyphenyl) n-octane, 1,1-bis (4-hydroxyphenyl) n-nonane, 1,1- Bis (4-hydroxyphenyl) n-decane, 1,1-bis (4-hydroxyphenyl) n-dodecane, 1,1-bis (4-hydroxyphenyl) -2-methylpropane, 1,1-bis (4 -Hydroxyphenyl) -3-methylbutane, 1,1-bis (4-hydroxyphenyl) -3-methylpentane, 1,1-bis (4-hydroxyphenyl) -2, -Dimethylpentane, 1,1-bis (4-hydroxyphenyl) -2-ethylbutane, 1,1-bis (4-hydroxyphenyl) -2-ethylhexane, 1,1-bis (4-hydroxyphenyl) -3 , 7-Dimethyloctane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane, 1-phenyl-1,1-bis ( 4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxyphenyl) n-butane, 2,2-bis (4-hydroxyphenyl) n-pentane, 2,2-bis (4-hydroxyphenyl) n-hexane, 2,2-bis (4-hydroxyphenyl) n-heptane, 2,2-bis (4 -Hydroxyphenyl) n-octane, 2,2-bis (4-hydroxyphenyl) n-nonane, 2,2-bis (4-hydroxyphenyl) n-decane, 2,2-bis (4-hydroxyphenyl) n -Dodecane, 2,2-bis (4-hydroxyphenyl) ethyl propionate, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 2,2-bis (4-hydroxyphenyl) -4- Methylhexane, 2,2-bis (4-hydroxyphenyl) hexafluoropropane, 2,2-bis (4-hydroxy-3-methylphenyl) propane, 9,9-bis (4-hydroxy-3-methylphenyl) Fluorene, 1,3-bis [2- (4-hydroxyphenyl) -2-propyl] benzene, bis (2-hydroxyphenyl) methane, 1,1, - tris (4-hydroxyphenyl) ethane, 2,2-bis (3-methyl-4-hydroxyphenyl) butane, 4-t-butyl-2 ', may be mentioned 4'-dihydroxy benzophenone.

  A compound having a phenolic hydroxyl group can exhibit the most effective thermochromic properties, but aromatic carboxylic acids and aliphatic carboxylic acids having 2 to 5 carbon atoms, carboxylic acid metal salts, acidic phosphoric acid esters and their metals. It may be a compound selected from salts, 1,2,3-triazole and its derivatives.

  The reaction medium that determines the temperature at which the color reaction by the electron-donating color-forming organic compound and the electron-accepting compound occurs will be described. Examples of the reaction medium include compounds such as alcohols, esters, ketones, ethers and acid amides. When these compounds are used for microencapsulation and secondary processing, low-molecular-weight compounds evaporate outside the capsule when subjected to high heat treatment, so in order to hold them stably inside the capsule, the number of carbon atoms is 10 or more. Compounds of are preferably used.

  As the alcohol, an aliphatic monovalent saturated alcohol having 10 or more carbon atoms is effective. Specific examples thereof include decyl alcohol, undecyl alcohol, dodecyl alcohol, tridecyl alcohol, tetradecyl alcohol, pentadecyl alcohol, hexadecyl alcohol, heptadecyl alcohol, octadecyl alcohol, eicosyl alcohol and docosyl alcohol.

  As the esters, esters having 10 or more carbon atoms are effective, and any combination of a monovalent carboxylic acid having an aliphatic and alicyclic or aromatic ring and a monohydric alcohol having an aliphatic, alicyclic or aromatic ring. , An aliphatic, alicyclic or aromatic ring-containing polyvalent carboxylic acid, and an ester, an aliphatic or alicyclic ring obtained from any combination of an aliphatic, alicyclic or aromatic ring-containing monohydric alcohol Alternatively, there may be mentioned esters obtained from any combination of a monovalent carboxylic acid having an aromatic ring and a polyhydric alcohol having an aliphatic and alicyclic or aromatic ring. Specifically, ethyl caprylate, octyl caprylate, stearyl caprylate, myristyl caprate, docosyl caprate, 2-ethylhexyl laurate, n-decyl laurate, 3-methylbutyl myristate, cetyl myristate, isopropyl palmitate, Neopentyl palmitate, nonyl palmitate, cyclohexyl palmitate, n-butyl stearate, 2-methylbutyl stearate, 3,5,5-trimethylhexyl stearate, n-undecyl stearate, pentadecyl stearate, stearyl stearate, stearin Cyclohexyl methyl acid, isopropyl behenate, hexyl behenate, lauryl behenate, behenyl behenate, cetyl benzoate, p-tert-butyl stearyl benzoate stearyl, diimiphthalate Stille, distearyl phthalate, dimyristyl oxalate, dicetyl oxalate, dicetyl malonate, dilauryl succinate, dilauryl glutarate, diundecyl adipate, dilauryl azelate, di- (n-nonyl) sebacate, 1,18-octadecyl Dyneopentyl methylene dicarboxylate, ethylene glycol dimyristate, propylene glycol dilaurate, propylene glycol distearate, hexylene glycol dipalmitate, 1,5-pentanediol distearate, 1,2,6-hexanetriol trimyristate, 1,4-cyclohexanediol didecyl, 1,4-cyclohexanedimethanol dimyristate, xylene glycol dicaprinate, xylene glycol distearate and the like can be mentioned.

  Ester compounds selected from esters of saturated fatty acids and branched aliphatic alcohols and esters of unsaturated fatty acids or saturated fatty acids having a branched or substituted group and branched or having 16 or more carbon atoms are also effective. is there. Specifically, 2-ethylhexyl butyrate, 2-ethylhexyl behenate, 2-ethylhexyl myristate, 2-ethylhexyl caprate, 3,5,5-trimethylhexyl laurate, 3,5,5-trimethylhexyl palmitate, 3,5,5-Trimethylhexyl stearate, 2-methylbutyl caproate, 2-methylbutyl caprylate, 2-methylbutyl caprate, 1-ethylpropyl palmitate, 1-ethylpropyl stearate, 1-ethylpropyl behenate, 1-ethylhexyl laurate, 1-ethylhexyl myristate, 1-ethylhexyl palmitate, 2-methylpentyl caproate, 2-methylpentyl caprylate, 2-methylpentyl caprate, 2-methylpentyl laurate, 2-stearic acid stearate Met Butyl, 2-methylbutyl stearate, 3-methylbutyl stearate, 1-methylheptyl stearate, 2-methylbutyl behenate, 3-methylbutyl behenate, 1-methylheptyl stearate, 1-methylheptyl behenate, caproic acid 1 -Ethylpentyl, 1-ethylpentyl palmitate, 1-methylpropyl stearate, 1-methyloctyl stearate, 1-methylhexyl stearate, 1,1-dimethylpropyl laurate, 1-methylpentyl caprate, palmitic acid 2-methylhexyl, 2-methylhexyl stearate, 2-methylhexyl behenate, 3,7-dimethyloctyl laurate, 3,7-dimethyloctyl myristate, 3,7-dimethyloctyl palmitate, stearic acid 3, 7-Jime Ruoctyl, 3,7-dimethyloctyl behenate, stearyl oleate, behenyl oleate, stearyl linoleate, behenyl linoleate, 3,7-dimethyloctyl erucate, stearyl erucate, isostearyl erucate, cetyl isostearate, isostearine. Acid stearyl, 2-methylpentyl 12-hydroxystearate, 2-ethylhexyl 18-bromostearate, isostearyl 2-ketomyristate, 2-ethylhexyl 2-fluoromyristate, cetyl butyrate, stearyl butyrate, behenyl butyrate and the like. To be

  Furthermore, in order to exhibit a large hysteresis characteristic with respect to the color density-temperature curve and to change the color, and to impart the color memory property depending on the temperature change, the temperature of 5 ° C. or higher and less than 50 ° C. described in JP-B-4-17154 is used. Carboxylic acid ester compound showing ΔT value (melting point-clouding point), for example, carboxylic acid ester containing substituted aromatic ring in molecule, ester of carboxylic acid containing unsubstituted aromatic ring and aliphatic alcohol having 10 or more carbon atoms A carboxylic acid ester containing a cyclohexyl group in the molecule, a fatty acid having 6 or more carbon atoms and an unsubstituted aromatic alcohol or phenol, a fatty acid having 8 or more carbon atoms and a branched aliphatic alcohol or ester, a dicarboxylic acid and an aromatic alcohol, or Esters of branched aliphatic alcohols, dibenzyl cinnamate, heptyl stearate, didecyl adipate, adipine Dilauryl, dimyristyl adipate, dicetyl adipate, distearyl adipate, trilaurin, trimyristin, tristearin, dimyristin, distearate, and the like.

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

  As the ketones, aliphatic ketones having a total carbon number of 10 or more are effective. Specifically, 2-decanone, 3-decanone, 4-decanone, 2-undecanone, 3-undecanone, 4-undecanone, 5-undecanone, 2-dodecanone, 3-dodecanone, 4-dodecanone, 5-dodecanone, 2 -Tridecanone, 3-Tridecanone, 2-Tetradecanone, 2-Pentadecanone, 8-Pentadecanone, 2-Hexadecanone, 3-Hexadecanone, 9-Heptadecanone, 2-Pentadecanone, 2-Octadecanone, 2-Nonadecanone, 10-Nonadecanone, 2-Eicosanone , 11-eicosanone, 2-heneicosanone, 2-docosanone, lauron, stearone and the like.

  Further, as the ketones, arylalkyl ketones having a total carbon number of 12 to 24, for example, n-octadecanophenone, n-heptadecanophenone, n-hexadecanophenone, n-pentadecanophenone, n -Tetradecanophenone, 4-n-dodecaacetophenone, n-tridecanophenone, 4-n-undecanoacetophenone, n-laurophenone, 4-n-decanoacetophenone, n-undecanophenone, 4-n- Nonylacetophenone, n-decanophenone, 4-n-octylacetophenone, n-nonanophenone, 4-n-heptylacetophenone, n-octanophenone, 4-n-hexylacetophenone, 4-n-cyclohexylacetophenone, 4-tert-butyl. Propiophenone, n-heptaphenone, 4-n-pe Chill acetophenone, phenyl ketone, benzyl -n- butyl ketone, 4-n-butyl acetophenone, n- hexanophenone, 4-isobutyl acetophenone, 1-acetonaphthone, 2-acetonaphthone, cyclopentyl phenyl ketone.

  As the ethers, aliphatic ethers having a total carbon number of 10 or more are effective. Specifically, dipentyl ether, dihexyl ether, diheptyl ether, dioctyl ether, dinonyl ether, didecyl ether, diundecyl ether, didodecyl ether, ditridecyl ether, ditetradecyl ether, dipentadecyl ether, dihexadecyl ether. Examples thereof include decyl ether, dioctadecyl ether, decanediol dimethyl ether, undecanediol dimethyl ether, dodecanediol dimethyl ether, tridecanediol dimethyl ether, decanediol diethyl ether, and undecanediol diethyl ether.

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

  Further, as the reaction medium, a compound represented by the following formula (1) can also be used.

  In the formula, R1 represents a hydrogen atom or a methyl group, m represents an integer of 0 to 2, one of X1 and X2 represents-(CH2) nOCOR2 or-(CH2) nCOOR2, and the other represents a hydrogen atom, n represents an integer of 0 to 2, R2 represents an alkyl group or alkenyl group having 4 or more carbon atoms, Y1 and Y2 represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a methoxy group or a halogen atom, and r And p are integers from 1 to 3.

  Of the compounds represented by the formula (1), when R1 is a hydrogen atom, a reversible thermochromic composition having a wider hysteresis width can be obtained, which is preferable, and R1 is a hydrogen atom, and m Is more preferably 0. Among the compounds represented by formula (1), the compound represented by the following formula (2) is more preferably used.

  R in the formula (2) represents an alkyl group or an alkenyl group having 8 or more carbon atoms, preferably an alkyl group having 10 to 24 carbon atoms, and more preferably an alkyl group having 12 to 22 carbon atoms.

  Specific examples of the compound represented by the formula (2) include 4-benzyloxyphenylethyl octanoate, 4-benzyloxyphenylethyl nonanoate, 4-benzyloxyphenylethyl decanoate, and 4-benzyl undecanoate. Oxyphenylethyl, 4-benzyloxyphenylethyl dodecanoate, 4-benzyloxyphenylethyl tridecanoate, 4-benzyloxyphenylethyl tetradecanoate, 4-benzyloxyphenylethyl pentadecanoate, 4-benzyl hexadecanoate Examples include oxyphenylethyl, 4-benzyloxyphenylethyl heptadecanoate, and 4-benzyloxyphenylethyl octadecanoate.

  Furthermore, a compound represented by the following formula (3) can be used as a reaction medium.

  In formula (3), R represents an alkyl group or alkenyl group having 8 or more carbon atoms, m and n each represent an integer of 1 to 3, X and Y each represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms. Represents an alkoxy group having 1 to 4 carbon atoms or a halogen atom.

Specifically as the compound represented by the formula (3), 1,1-diphenylmethyl octanoate,
Nonanoic acid 1,1-diphenylmethyl, decanoic acid 1,1-diphenylmethyl, undecanoic acid 1,1-diphenylmethyl, dodecanoic acid 1,1-diphenylmethyl, tridecanoic acid 1,1-diphenylmethyl, tetradecanoic acid 1,1 Examples include diphenylmethyl, 1,1-diphenylmethyl pentadecanoate, 1,1-diphenylmethyl hexadecanoate, 1,1-diphenylmethyl heptadecanoate, and 1,1-diphenylmethyl octadecanoate.

  Furthermore, a compound represented by the following formula (4) can be used as a reaction medium.

  In the formula (4), X represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a methoxy group, or a halogen atom, m represents an integer of 1 to 3, and n represents an integer of 1 to 20. .

  Examples of the compound represented by the formula (4) include a diester of malonic acid and 2- [4- (4-chlorobenzyloxy) phenyl)] ethanol, and a diester of succinic acid and 2- (4-benzyloxyphenyl) ethanol. , A diester of succinic acid and 2- [4- (3-methylbenzyloxy) phenyl)] ethanol, a diester of glutaric acid and 2- (4-benzyloxyphenyl) ethanol, glutaric acid and 2- [4- ( 4-chlorobenzyloxy) phenyl)] ethanol diester, adipic acid 2- (4-benzyloxyphenyl) ethanol diester, pimelic acid 2- (4-benzyloxyphenyl) ethanol diester, suberic acid Of 2- (4-benzyloxyphenyl) ethanol, suberic acid and 2- [ Diester of-(3-methylbenzyloxy) phenyl)] ethanol, diester of suberic acid and 2- [4- (4-chlorobenzyloxy) phenyl)] ethanol, suberic acid and 2- [4- (2, 4-dichlorobenzyloxy) phenyl)] ethanol diester, azelaic acid 2- (4-benzyloxyphenyl) ethanol diester, sebacic acid 2- (4-benzyloxyphenyl) ethanol diester, 1, Diester of 10-decanedicarboxylic acid and 2- (4-benzyloxyphenyl) ethanol, diester of 1,18-octadecanedicarboxylic acid and 2- (4-benzyloxyphenyl) ethanol, 1,18-octadecanedicarboxylic acid 2- [4- (2-methylbenzyloxy) phenyl)] ethane It can be exemplified diester of Lumpur.

  Furthermore, a compound represented by the following formula (5) can be used as a reaction medium.

  In the formula (5), R represents an alkyl group or an alkenyl group having 1 to 21 carbon atoms, and n represents an integer of 1 to 3.

  Examples of the compound represented by the formula (5) include diesters of 1,3-bis (2-hydroxyethoxy) benzene and capric acid, diesters of 1,3-bis (2-hydroxyethoxy) benzene and undecanoic acid, 1 , 3-bis (2-hydroxyethoxy) benzene with lauric acid, 1,3-bis (2-hydroxyethoxy) benzene with myristic acid, 1,4-bis (hydroxymethoxy) benzene with butyric acid Diester of 1,4-bis (hydroxymethoxy) benzene and isovaleric acid, diester of 1,4-bis (2-hydroxyethoxy) benzene and acetic acid, 1,4-bis (2-hydroxyethoxy) Diester of benzene and propionic acid, 1,4-bis (2-hydroxyethoxy) benzene and valeric acid Diester of 1,4-bis (2-hydroxyethoxy) benzene with caproic acid, diester of 1,4-bis (2-hydroxyethoxy) benzene with caprylic acid, 1,4-bis (2-hydroxy) Examples include diesters of (ethoxy) benzene and capric acid, diesters of 1,4-bis (2-hydroxyethoxy) benzene and lauric acid, and diesters of 1,4-bis (2-hydroxyethoxy) benzene and myristic acid. .

  Further, a compound represented by the following formula (6) can be used as a reaction medium.

  In formula (6), X represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom, m represents an integer of 1 to 3, and n represents 1 To an integer of 20.

  Examples of the compound represented by the formula (6) include a diester of succinic acid and 2-phenoxyethanol, a diester of suberic acid and 2-phenoxyethanol, a diester of sebacic acid and 2-phenoxyethanol, 1,10-decanedicarboxylic acid and 2 Examples include a diester of phenoxyethanol and a diester of 1,18-octadecanedicarboxylic acid and 2-phenoxyethanol.

  Furthermore, a compound represented by the following formula (7) can be used as a reaction medium.

  In formula (7), R represents an alkyl group having 4 to 22 carbon atoms, a cycloalkylalkyl group, a cycloalkyl group or an alkenyl group having 4 to 22 carbon atoms, and X represents a hydrogen atom or 1 to 4 carbon atoms. Represents an alkyl group, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom, and n represents 0 or 1.

  Examples of the compound represented by the formula (7) include decyl 4-phenylbenzoate, lauryl 4-phenylbenzoate, myristyl 4-phenylbenzoate, cyclohexylethyl 4-phenylbenzoate, octyl 4-biphenylacetate, and 4-biphenylacetic acid. Nonyl, decyl 4-biphenylacetate, lauryl 4-biphenylacetate, myristyl 4-biphenylacetate, tridecyl 4-biphenylacetate, pentadecyl 4-biphenylacetate, cetyl 4-biphenylacetate, cyclopentyl 4-biphenylacetate, cyclohexylmethyl 4-biphenylacetate Examples include hexyl 4-biphenylacetate and cyclohexylmethyl 4-biphenylacetate.

  Further, a compound represented by the following formula (8) can be used as a reaction medium.

  In formula (8), R represents either an alkyl group having 3 to 18 carbon atoms or an aliphatic acyl group having 3 to 18 carbon atoms, and X is a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or 1 carbon atom. Or 2 represents an alkoxy group or a halogen atom, Y represents a hydrogen atom or a methyl group, Z represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 or 2 carbon atoms. , Or a halogen atom.

  Examples of the compound represented by the formula (8) include phenoxyethyl 4-butoxybenzoate, phenoxyethyl 4-pentyloxybenzoate, phenoxyethyl 4-tetradecyloxybenzoate, phenoxyethyl 4-hydroxybenzoate and dodecanoic acid. Examples thereof include esters and phenoxyethyl vanillic acid dodecyl ether.

  Furthermore, a compound represented by the following formula (9) can be used as a reaction medium.

  In formula (9), R represents an alkyl group having 4 to 22 carbon atoms, an alkenyl group having 4 to 22 carbon atoms, a cycloalkylalkyl group, or a cycloalkyl group, and X represents a hydrogen atom, an alkyl group, or an alkoxy. A group or a halogen atom, Y represents a hydrogen atom, an alkyl group, an alkoxy group, or a halogen atom, and n represents 0 or 1.

  Examples of the compound represented by the formula (9) include benzoic acid ester of octyl p-hydroxybenzoate, benzoic acid ester of decyl p-hydroxybenzoate, p-methoxybenzoic acid ester of heptyl p-hydroxybenzoate, and p-hydroxyl. Examples thereof include o-methoxybenzoic acid ester of dodecyl benzoate and benzoic acid ester of cyclohexylmethyl p-hydroxybenzoate.

  Furthermore, a compound represented by the following formula (10) can be used as a reaction medium.

  In formula (10), R is either an alkyl group having 3 to 18 carbon atoms, a cycloalkylalkyl group having 6 to 11 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, or an alkenyl group having 3 to 18 carbon atoms. X represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, or a halogen atom, and Y represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or methoxy. A group, an ethoxy group, or a halogen atom is shown.

  Examples of the compound represented by the formula (10) include phenoxyethyl ether of nonyl p-hydroxybenzoate, phenoxyethyl ether of decyl p-hydroxybenzoate, phenoxyethyl ether of undecyl p-hydroxybenzoate, and phenoxyethyl dodecyl vanillate. An example is ether.

  Furthermore, a compound represented by the following formula (11) can be used as a reaction medium.

  In formula (11), R represents a cycloalkyl group having 3 to 8 carbon atoms or a cycloalkylalkyl group having 4 to 9 carbon atoms, and n represents an integer of 1 to 3.

  Examples of the compound represented by the formula (11) include diesters of 1,3-bis (2-hydroxyethoxy) benzene and cyclohexanecarboxylic acid, and diesters of 1,4-bis (2-hydroxyethoxy) benzene and cyclohexanepropionic acid. , A diester of 1,3-bis (2-hydroxyethoxy) benzene and cyclohexanepropionic acid can be exemplified.

  Furthermore, a compound represented by the following formula (12) can be used as a reaction medium.

  In formula (12), R represents an alkyl group having 3 to 17 carbon atoms, a cycloalkyl group having 3 to 8 carbon atoms, or a cycloalkylalkyl group having 5 to 8 carbon atoms, and X represents a hydrogen atom or 1 to 1 carbon atoms. 5 represents an alkyl group, a methoxy group, an ethoxy group, or a halogen atom, and n represents an integer of 1 to 3.

  Examples of the compound represented by the formula (12) include a diester of 4-phenylphenol ethylene glycol ether and cyclohexanecarboxylic acid, a diester of 4-phenylphenol diethylene glycol ether and lauric acid, 4-phenylphenol triethylene glycol ether and cyclohexanecarboxylic acid. Acid diester, 4-phenylphenol ethylene glycol ether and octanoic acid diester, 4-phenylphenol ethylene glycol ether and nonanoic acid diester, 4-phenylphenol ethylene glycol ether and decanoic acid diester, 4-phenyl Examples thereof include diesters of phenol ethylene glycol ether and myristic acid.

  Further, as the electron-accepting compound, a specific alkoxyphenol compound having a linear or side chain alkyl group having 3 to 18 carbon atoms is used (Japanese Patent Application Laid-Open Nos. 11-129623 and 11-5973) or a specific Using a hydroxybenzoic acid ester (Japanese Patent Laid-Open No. 2001-105732), using a gallic acid ester or the like (Japanese Patent Publication No. 51-44706, Japanese Patent Laid-Open No. 2003-253149), a coloring type by heating (coloring by heating, It is also possible to apply a reversible thermochromic composition which is decolored by cooling) and a reversible thermochromic microcapsule pigment (reversible thermochromic pigment) containing the reversible thermochromic composition.

  The reversible thermochromic composition is a compatible solution containing an electron-donating color-developing organic compound, an electron-accepting compound and a reaction medium as essential components. The proportion of each component may be appropriately selected depending on the density, the color change temperature, the color change form, the type of each component, and the like. Generally, the component ratio for obtaining desired characteristics is such that the electron-accepting compound is 0.1 to 100 parts by mass, preferably 0.1 to 50 parts by mass, relative to 1 part by mass of the electron-donating color-forming organic compound. , More preferably 0.5 to 20 parts by mass, and the reaction medium is 5 to 200 parts by mass, preferably 5 to 100 parts by mass, more preferably 10 to 100 parts by mass.

  The reversible thermochromic microcapsule pigment may further contain various light stabilizers, if necessary. The light stabilizer is contained in order to prevent photodegradation of the reversible thermochromic composition, and is 0.3 part by mass or more and 24 parts by mass or less, preferably 0 part by mass with respect to 1 part by mass of the electron-donating color-developing organic compound. It is contained in a proportion of not less than 3 parts by mass and not more than 16 parts by mass. Further, among the light stabilizers, the ultraviolet absorber effectively blocks ultraviolet rays contained in sunlight and the like to prevent photodegradation caused by an excited state due to a photoreaction of the electron-accepting compound. Further, antioxidants, singlet oxygen quenchers, superoxide anion quenchers, ozone quenchers and the like suppress the oxidation reaction due to light. The light stabilizers may be used alone or in combination of two or more.

  The reversible thermochromic composition is used as a reversible thermochromic microcapsule pigment by being encapsulated in microcapsules. The microencapsulation method includes conventionally known interfacial polymerization method, in situ polymerization method, submerged curing coating method, phase separation method from aqueous solution, phase separation method from organic solvent, melt dispersion cooling method, gas There are a medium suspension coating method, a spray drying method and the like, which are appropriately selected depending on the application. Further, the surface of the microcapsules may be provided with a secondary resin film depending on the purpose to impart durability or may be modified in surface characteristics for practical use.

  The content of the microcapsule pigment is preferably in the range of inclusion / wall film = 7/1 to 1/1 (mass ratio), and when the ratio of the wall film is within the above range, the color density and vividness at the time of color development are clear. It is possible to prevent deterioration of the property, and more preferably, inclusion / wall film = 6/1 to 1/1 (mass ratio).

  By encapsulating the reversible thermochromic composition in microcapsules, a chemically and physically stable pigment can be constructed.

The microcapsule pigment prepared from the above has a volume average particle diameter of 0.1 to 5 μm, and when it does not contain microcapsule pigment particles having a particle diameter of more than 8 μm, the coloring power of the microcapsule pigment is good. In addition, it suppresses clogging of the ink flow path and printer head in the inkjet printer to improve ink ejection from the nozzle, and furthermore, when ejecting ink, it is easy to form ink droplets with a uniform diameter. It is possible to form a high-definition printed image with excellent properties.
It should be noted that if the microcapsule pigment particles having a particle size of more than 8 μm are not included, the microcapsule pigment particles having a particle size of more than 8 μm are likely to cause a clogging, so that those that substantially affect are not included. It means controlling. Regarding the ink of the present invention which does not contain microcapsule pigment particles having a particle size of more than 8 μm, the microcapsule pigment particles having a particle size of more than 6 μm when the upper limit of the volume average particle size is 4 μm or less as described later. When the upper limit of the volume average particle diameter is 3 μm or less, it is preferable that the microcapsule pigment particles having a particle diameter of more than 4 μm are not included.

Considering that the coloring power and the ink dischargeability of the microcapsule pigment are good and the droplets having a uniform diameter are easily formed at the time of ink discharge, the microcapsule pigment has an upper limit of the volume average particle diameter. The thickness is preferably 4 μm or less, more preferably 3 μm or less. The upper limit value is specified as described above because it is possible to secure a substantial color density when the microcapsule pigment has a size of about 2 μm, but it is easier to secure the color density when the microcapsule pigment is larger. If present, it is not preferable from the viewpoints of continuous ejection stability, prevention of clogging, prevention of sedimentation, etc. Therefore, it is essential that the volume average particle diameter be 5 μm or less. For the same reason, the upper limit value is preferably 4 μm or less, more preferably 3 μm or less.
Furthermore, the lower limit of the volume average particle diameter is preferably 0.3 μm or more, more preferably 0.5 μm or more. In order to specify the lower limit as described above, it is necessary to be 0.1 μm or more from the viewpoint of color developability, and if it is less than that, it is difficult to obtain a sufficient color density. Further, for the same reason, the lower limit value is preferably 0.3 μm or more, more preferably 0.5 μm or more.

  Specific examples of the microcapsule pigment contained in the ink composition include a microcapsule pigment having a volume average particle size of 0.1 to 5.0 μm and not containing microcapsule pigment particles having a particle size of more than 8 μm, and a volume average particle size. A microcapsule pigment having a particle size of 0.3 to 5.0 μm and not including a microcapsule pigment particle having a particle size of more than 8 μm, a volume average particle size of 0.5 to 5.0 μm, and a particle of more than 8 μm Microcapsule pigments not containing microcapsule pigment particles having a diameter, microcapsule pigments having a volume average particle diameter of 0.1 to 4.0 μm and not containing microcapsule pigment particles having a particle diameter exceeding 6 μm, volume average particles A microcapsule pigment particle having a diameter of 0.3 to 4.0 μm and having a particle diameter of more than 6 μm. (B) Capsule pigment, volume average particle diameter is 0.5 to 4.0 μm, microcapsule pigment not containing microcapsule pigment particles having a particle diameter of more than 6 μm, volume average particle diameter is 0.1 to 3.0 μm. Microcapsule pigments not containing microcapsule pigment particles having a particle size of more than 4 μm, microcapsules having a volume average particle size of 0.3 to 3.0 μm and not containing microcapsule pigment particles having a particle size of more than 4 μm. Examples thereof include pigments and microcapsule pigments having a volume average particle diameter of 0.5 to 3.0 μm and not containing microcapsule pigment particles having a particle diameter of more than 4 μm.

  When forming a printed image using an inkjet printer, using a multicolored ink such as cyan, magenta, yellow, and black, or a multicolored ink composition of the same color with different discoloration temperatures, If all the inks are not ejected well, it becomes difficult to form a print image with high definition and a wide variety of hues, or a print image whose appearance changes due to temperature change. However, by setting the average particle size and particle size of the microcapsule pigment contained in the ink composition of each color as described above, the colorability of each ink composition, the ink dischargeability, and the droplets having a uniform diameter at the time of ink discharge Since the formability is good, it is possible to form a high-definition printed image with excellent color development, or to form a printed image whose appearance changes with changes in temperature.

The particle diameter and volume average particle diameter are measured by determining the area of the particle using image analysis type particle size distribution measurement software "MacView" manufactured by Mountech Co., Ltd., and the projected area circle equivalent diameter (from the area of the area of the particle). (Heywood diameter) is calculated, and is the value measured as the average particle diameter of particles corresponding to equal volume spheres.
If all or most of the particles have a particle size of more than 0.2 μm, a particle size distribution measuring device (Beckman Coulter, Inc., product name: Multisizer 4e) is used to obtain an equivalent volume sphere by the Coulter method. It is also possible to measure as the average particle diameter of the particles.
Further, based on the numerical value measured using the software or the measuring device, a laser diffraction / scattering particle size distribution measuring device (device name: LA-300, manufactured by Horiba Ltd.) was used for calibration. After that, the volume-based particle diameter and the average particle diameter may be measured.

  The microcapsule pigment may have a circular cross-section or a non-circular cross-section.

  The microcapsule pigments may be used alone or in combination of two or more. The content of the microcapsule pigment in the ink composition is, for example, 3% by mass or more and 30% by mass or less, preferably 5% by mass or more and 20% by mass or less, and more preferably 10% by mass or more and 15% by mass or less. . When the content rate of the microcapsule pigment is within the above range, aggregation of the microcapsule pigment is suppressed, and the ink ejection property from the printer head is easily improved.

Microcapsule pigments can have any zeta potential.
Considering the dispersibility of the microcapsule pigment, the microcapsule pigment preferably has a positive or negative zeta potential in the ink composition containing water and the microcapsule pigment. When the zeta potential is 0 mV, the dispersibility of the microcapsule pigment is reduced and aggregates are easily formed.

  When the microcapsule pigment has a positive or negative zeta potential, the ink composition has a dispersant having a functional group having a charge having a sign opposite to the zeta potential of the microcapsule pigment in the ink composition. Also by adding, it is possible to form a high-definition printed image with rich color development.

The dispersant, by strongly adsorbing the functional group on the surface of the microcapsule pigment, prevents the microcapsule pigments from approaching each other and aggregating, enhances the dispersibility of the microcapsule pigment, and Good color development and ink fluidity.
For this reason, clogging of the ink flow path in the inkjet printer and the printer head is suppressed, and the ink ejection from the nozzle becomes good, and at the time of ink ejection, ink droplets having excellent color development and a uniform diameter are formed. Since it is easy to form, it is possible to form a high-definition printed image with rich color development.

The microcapsule pigment may have an arbitrary zeta potential, but in view of improving the thermal discoloration of the microcapsule pigment, it is preferable that the zeta potential has a low absolute value.
If the absolute value of the zeta potential is low, the reason is not clear, but in the thermochromic function due to the components (a), (b), and (c), there is a difference between the components (a), (b), and (c). Since it has little influence on the transfer of electrons, the discoloration sensitivity is not impaired, and residual color such as residual color is less likely to occur during erasing.
Further, when the absolute value of the zeta potential of the microcapsule pigment is low, no trouble occurs even if the microcapsule pigment and the additive having a high absolute value of the zeta potential in the ink composition are combined, so that the zeta potential is low. There is a degree of freedom to use additives with various values, and stable ink can be prepared.

  The zeta potential can be measured using a trade name: streaming potential measuring device Stabino PMX400, manufactured by Microtrac Bell Co., Ltd.

(Dispersant)
Specific examples of the dispersant include a styrene-maleic acid copolymer and its alkali-neutralized product, an olefin-maleic acid copolymer and a substance having a structure having a functional group having a negative charge in the ink composition. Examples thereof include alkali neutralized products, acrylic polymer compounds, and synthetic resins such as styrene-acrylic acid copolymers.
Examples of the substance having a structure having a positively charged functional group in the ink composition include dimethylaminoethyl acrylate, dialkylaminoacrylic acid ester such as diethylaminoethyl acrylate, dialkylaminomethacrylic acid ester such as dimethylaminoethyl methacrylate, Dialkylaminostyrenes such as dimethylaminostyrene, diethylaminostyrene, and methylethylaminostyrene and quaternary ammonium derivatives thereof, methacryloxyethyltrimethylammonium chloride, methacrylamidopropyltrimethylammonium chloride, 2-hydroxy-3-methacryloxypropyltrimethylammonium chloride, Monomers such as vinylbenzyltrimethylammonium chloride and the above-mentioned unsaturated vinyl monomers (cat It can be mentioned copolymers of the illustrated ones) and the emission resin emulsion as used in obtaining the emulsion polymerization.

  Among the dispersants, considering that the dispersibility of the microcapsule pigment is better, the substance having a functional group having a negative charge in the structure of the ink composition is an olefin-maleic acid copolymer. And alkali-neutralized products thereof, and acrylic polymer compounds are preferable, and acrylic polymer compounds are particularly preferable. As the acrylic polymer compound, it is possible to use substances such as polyacrylic acid, acrylic acid-maleic acid copolymer, acrylic urethane copolymer, and alkali-neutralized products thereof, more preferably a carboxyl group. And an acrylic polymer compound having a comb structure having a carboxyl group in its side chain. A particularly preferred dispersant is an acrylic polymer compound having a comb structure having a plurality of carboxyl groups in its side chain, and specific examples thereof include product name: Sols Perth 43000, manufactured by Nippon Lubrizol Co., Ltd.

  Examples of the substance having a structure having a positively charged functional group in the ink composition include dialkylaminoacrylic acid esters such as dimethylaminoethyl acrylate and diethylaminoethyl acrylate, and dialkylaminomethacrylic acid esters such as dimethylaminoethyl methacrylate. preferable.

  The content of the dispersant is 0.01 to 2 with respect to the total amount of the ink composition, in consideration of suppressing excessive thickening of the ink composition and improving the dispersibility of the microcapsule pigment. It is preferably contained in an amount of 0.1% by mass, and preferably 0.1 to 1.5% by mass.

(Ink composition)
The ink composition of the present invention may contain the following components, if necessary. Specifically, wetting agents such as ethylene glycol, propanediol, butanediol, pentanediol, diethylene glycol, glycerin, polyethylene glycol and polypropylene glycol, radical polymerizable compounds, polyvinyl alcohol, polyvinylpyrrolidone, urethane resins, styrene-butadiene resins. , Alkyd resin, sulfamide resin, maleic acid resin, polyvinyl acetate resin, ethylene vinyl acetate resin, vinyl chloride-vinyl acetate resin, copolymer of styrene and maleic acid ester, styrene-acrylonitrile resin, cyanate-modified polyalkylene glycol, ester Gum, xylene resin, urea resin, urea aldehyde resin, phenol resin, alkylphenol resin, terpene phenol resin, rosin resin and its hydrogenated compound, rosin resin Fixing agents such as nole resins, polyvinyl alkyl ethers, polyamide resins, polyolefin resins, nylon resins, polyester resins, cyclohexanone resins, surfactants, preservatives, rust inhibitors, antifungal agents, antioxidants, ultraviolet absorbers, Examples include conventionally known substances such as a polymerization initiator, a chelating agent, a pH adjusting agent, a viscosity adjusting agent, and a shear thinning agent.
Among the above components, when a radical polymerizable compound and a radical polymerization initiator are used in the ink composition, when the printed image is irradiated with light, particularly UV light, the radical polymerizable compound is immediately polymerized to form an ink composition. Since the object quickly adheres to the surface to be printed, the fixability of the printed image can be further enhanced.

  As the radically polymerizable compound, (meth) acrylates, (meth) acrylamides, aromatic vinyls, allyl compounds, N-vinyl compounds, vinyl esters (vinyl acetate, vinyl propionate, vinyl versatate, etc.), allyl Esters (allyl acetate, etc.), halogen-containing monomers (vinylidene chloride, vinyl chloride, etc.), vinyl ethers (methyl vinyl ether, butyl vinyl ether, hexyl vinyl ether, methoxy vinyl ether, 2-ethylhexyl vinyl ether, methoxyethyl vinyl ether, cyclohexyl vinyl ether, chloro) Examples thereof include ethyl vinyl ether), vinyl cyanide ((meth) acrylonitrile etc.) and olefins (ethylene, propylene etc.). In the present specification, "(meth) acrylate" when referring to both or any of "acrylate" and "methacrylate" and "(meth)" when referring to both or any of "acrylic" and "methacryl" "Acrylic" may be described.

  In addition, as the radical polymerization initiator, aromatic ketones, aromatic onium salt compounds, organic peroxides, hexaarylbiimidazole compounds, ketoxime ester compounds, borate compounds, azinium compounds, metallocene compounds, active ester compounds , A compound having a carbon-halogen bond, and the like.

The viscosity of the ink composition can be adjusted to any numerical value as long as the ink composition can be satisfactorily ejected from the nozzle of the printer head, but it is preferably 2 to 2 when measured at a rotation speed of 30 rpm. It is preferably 30 mPa · s, and more preferably 3 to 20 mPa · s.
When the viscosity is set to the above numerical value, ink is easily ejected from the printer head nozzle, and it is easy to suppress the aggregation of the microcapsule pigment in the ink while facilitating the formation of ink droplets having a uniform diameter.
The viscosity can be measured at 20 ° C. using a BL type viscometer (product name: TVB-M type viscometer, L type rotor, manufactured by Toki Sangyo Co., Ltd.).

The surface tension of the ink composition is preferably 20 to 50 mN / m, and more preferably 20 to 35 mN / m. By setting the surface tension within the above numerical range, it becomes easy to enhance the permeability of the ink composition and improve the drying property of the printing surface.
The surface tension is obtained by measuring the surface tension using a surface tension measuring instrument manufactured by Kyowa Interface Science Co., Ltd. in a 20 ° C. environment using a glass plate by the vertical plate method.

  The pH value of the ink composition is preferably 4 to 8 at 20 ° C., more preferably 5 to 7 in consideration of improving the stability of the ink composition over time.

  The water-based ink composition according to the present invention can be produced by any conventionally known method. Specifically, it can be produced by mixing the above-mentioned respective components in necessary amounts and mixing them with various stirrers such as a propeller stirrer, homodisper or homomixer, and various dispersers such as a bead mill.

  The ink composition of the present invention is used in an inkjet printer printing machine.

(Ink container)
The ink composition may be contained in an ink container.
The ink container is not particularly limited as long as it can contain the ink composition, and can be selected from various constituent materials and forms.
Examples of the constituent material include plastics such as polyethylene terephthalate (PET) and polypropylene (PP), various metals (including alloys), polyethylene, ethylene vinyl acetate copolymer, and polyolefins such as polypropylene. it can. Further, the present invention is not limited to these, and may be a polymer obtained by blending or laminating the above-mentioned polymers in an appropriate ratio, a film thereof, or the like.
Examples of the form of the ink container include a pack, a bottle, a tank, a bottle, and a can.

The ink container may be provided with a plurality of ink storage chambers that are independent of each other, and each of the chambers may store a plurality of colors of ink composition so that the inks in the chambers have different colors.
Also, a plurality of ink containers can be combined to form an ink container set. The ink container set may be composed of the same color ink or plural colors of ink.
Further, the ink container may have a structure that allows it to be attached to an inkjet printer and supply the ink composition from the ink container to the ink flow path.

(inkjet printer)
The ink composition of the present invention was not ejected from the ink containing portion containing the ink composition, the printer head, the ink supply channel for supplying ink from the ink containing portion to the printer head, and the nozzle of the printer head. An ink recovery flow path that returns ink from the printer head to the ink supply flow path, and is accommodated in an inkjet printer that circulates ink through the ink supply flow path, the printer head, and the ink recovery flow path.

  In the ink jet printer, ink is prevented from accumulating in the ink flow path (indicating the ink supply flow path and the ink recovery flow path) and the printer head due to ink circulation, and agglomeration of the microcapsule pigment is suppressed. Makes ink discharge from ink good.

In consideration of suppressing the aggregation of the microcapsule pigment, it is preferable that the printer head be provided with a flow path for ink circulation in the printer head.
Since the printer head is provided with the above flow path, it is possible to easily circulate the ink in the printer head during the ink circulation and to suppress the ink retention in the printer head, so that the microcapsule pigment aggregates in the printer head. It is easy to suppress that.
The inkjet printer includes the above-mentioned mechanism, and the structure of the apparatus is not limited as long as ink circulation is possible, and may include a deaeration mechanism, a heating mechanism, and the like.

  The ink ejection method of the printer head is a known method, for example, a charge control method in which ink is ejected by using electrostatic attraction, a drop-on-demand method (pressure pulse method) in which vibration pressure of a piezo element is used, or an electric method. An acoustic inkjet method in which a signal is converted into an acoustic beam to irradiate the ink and the ink is ejected by using radiation pressure, a thermal ink jet (Bubble Jet (registered trademark) that uses the pressure generated by heating the ink to form bubbles ) Method etc. can be adopted suitably.

  The nozzle of the printer head has an inner diameter capable of favorably ejecting the ink composition. The inner diameter is preferably 10 μm to 100 μm, more preferably 10 μm to 50 μm, in consideration of improving the color developability and fineness of the printed image. The more preferable inner diameter of the nozzle is 10 to 30 μm.

When the ink composition contains a radical polymerizable compound and a radical polymerization initiator, the inkjet printer preferably includes a UV light irradiation section.
By irradiating the printed image formed by the ink composition with UV light, the radically polymerizable compound is polymerized and the ink composition is quickly fixed to the printed surface, so that the fixability of the printed image can be improved. .
Further, the ink container may be capable of mounting the ink container.

  An example of the inkjet printer according to this embodiment will be described below with reference to the drawings.

FIG. 3 is a schematic diagram illustrating an example of the configuration of an inkjet printer including an ink circulation mechanism. The ink supply device 1 shown in FIG. 3 includes an ink container 2, a printer head 3, an ink supply channel 4a, a pump 5, a wiping means 6, and a head for returning ink to the ink supply channel 4a to circulate the ink. The flow path 4b (flow path on the left side of the printer head 3 in the drawing) is provided.
The printer head 3 is formed with an ink ejection portion 8 of a plurality of nozzles 7 for ejecting the ink composition 9 on one surface, and the ink composition 9 in the nozzle 7 is extruded by a piezoelectric element or the like, whereby The ink composition 9 is discharged from the ink discharge port 8. Further, the printer head 3 includes an ink intake port 3b for taking in the ink composition from the ink supply flow path 4a, an ink exhaust port 3a for exhausting the ink composition to the ink recovery flow path 4b, a plurality of nozzles 7, and an ink intake port. It has an internal flow path 3c that connects the inlet 3b and the ink discharge port 3a.

  The ink circulation path is a path for connecting the ink intake port 3b of the printer head 3 and the ink discharge port 3a with an ink flow path to circulate the ink composition 9. In FIG. 3, an ink supply flow path 4a, an internal flow path 3c of the printer head 3, and an ink recovery flow path 4b form an annular path to circulate the ink composition 9. While the printing is stopped, the ink composition 9 is circulated in the annular path in order to prevent the microcapsule pigments of the ink composition 9 from settling and aggregating the microcapsule pigments in the printer head 3. Is preferred. For the ink supply channel 4a and the ink recovery channel 4b, for example, a tube having a diameter of 1 to 10 mm can be used, and a silicon-based pipe can be used as the material. The length of one round of the circulation path can be 800 mm to 10 m, further 1 to 9 m, and particularly 3 to 8 m.

  The pump 5 is arranged on the upstream side of the printer head 3 in the ink supply flow path 4 a and supplies the ink composition 9 to the printer head 3. By supplying the ink composition 9 to the printer head 3 and circulating the ink composition 9 in the annular path, the ink composition 9 in the internal flow path 3c of the printer head 3 flows, and the ink composition in the printer head 3 flows. It is possible to prevent the microcapsule pigment components of Item 9 from settling and aggregating the microcapsule pigment components.

  It is preferable to circulate the ink composition by a pump during inkjet printing. Further, while the inkjet printing is stopped, it is preferable that a cap (not shown) is attached to the nozzle discharge portion to circulate the ink composition.

  The inkjet printer ejects a desired image such as paper, synthetic paper, coated paper, plastic sheet, plastic, wood, metal, glass, and other shaped objects, cloth, non-woven fabric, etc. to form an appropriate printed image and reversible heat. A discolored printed matter is obtained.

Example 1
(Preparation of reversible thermochromic microcapsule pigment)
As component (a), 9-ethyl- (3-methylbutyl) amino-spiro [12H-benzo [a] xanthene-12,1 '(3H) -isobenzofuran] -3'-one 6.0 parts, (b) A reversible color-changing color memory composition consisting of 15.0 parts of 4,4 '-(2-ethylhexylidene) bisphenol as a component and 50.0 parts of 4-benzyloxyphenylethyl caprate as a component (c) was uniformly applied. Is heated and dissolved in, and a solution obtained by mixing 40.0 parts of an aromatic polyvalent isocyanate prepolymer as a wall film material and 50.0 parts of a cosolvent is emulsified and dispersed in a 10% polyvinyl alcohol aqueous solution to form fine droplets. After continuing stirring while heating, 2.5 parts of a water-soluble aliphatic modified amine was added, and stirring was further continued to obtain a microcapsule pigment suspension.
A microcapsule pigment was obtained by filtering the suspension with a filter press.
The volume average particle diameter of the microcapsule pigment was 0.69 μm, and the maximum particle diameter was 2.27 μm.
The microcapsule pigment has a complete decolorization temperature of 60 ° C. and a complete color development temperature of −25 ° C., and changes its color from magenta to colorless due to temperature change.

(Preparation of reversible thermochromic ink composition for inkjet)
10.0 parts of the microcapsule pigment (previously cooled and developed), 14.0 parts of morpholinoethyl (meth) acrylate, 10.0 parts of piperazinoethyl (meth) acrylate, 2-hydroxy-3- (4-) Benzoylphenoxy) -N, N, N-trimethyl-1-propaneammonium chloride 1.0 part, ethylene glycol 5.0 parts, antifungal agent (trade name: Proxel XL-2, manufactured by Zeneca Corporation) 0.2 parts , 0.5 parts of a defoaming agent (silicon type, trade name: SN deformer 381, manufactured by San Nopco Co., Ltd.) and 59.3 parts of water were uniformly mixed to prepare a reversible thermochromic ink composition.

(inkjet printer)
A printer head including an ink storage unit, a UV light irradiation unit for irradiating a print image with UV light, an ink supply channel for supplying ink from the ink storage unit to the printer head, and ink for the printer head An ink recovery flow path for returning the ink from the head to the ink supply flow path, and connecting the ink storage section, the printer head, the ink supply flow path, and the ink recovery flow path to the ink supply flow path, the printer head, and The ink composition was stored in the ink storage portion using an inkjet printer that enables ink circulation through the ink recovery channel.

  The printer head includes a nozzle having an inner diameter of 25 μm, an ink inlet for taking in the ink composition from an ink supply channel, an ink outlet for discharging the ink composition to an ink recovery channel, a nozzle, and an ink inlet. A printer head internal flow path that connects the inlet and the ink discharge port is provided.

  The circulation mechanism connects the pump and the ink recovery flow path between the ink storage part of the printer and the printer head between the ink storage part and the print head immediately before the ink circulation. And The flow rate of the ink composition in the flow channel (hereinafter referred to as "ink flow rate") was controlled by a pump. The ink supply channel and the ink recovery channel were made of silicone rubber.

Printing on recording paper (copy paper) and UV light irradiation were performed using the above inkjet printer to obtain a reversible thermochromic printed matter.
During printing, the circulation mechanism was operated to circulate the ink in the ink supply channel, the printer head, and the ink recovery channel.
A magenta reversible thermochromic image is visually recognized at room temperature (25 ° C.) on the printed matter, and the reversible thermochromic image is decolored by heating to 60 ° C. or higher, and a state before erasing at −25 ° C. ( It returned to the state in which magenta color printing was formed).
The reversible thermochromic image was formed by setting the decolored recording sheet again in the ink jet printer and printing was performed, and the printed matter could be repeatedly used.

Example 2
(Preparation of reversible thermochromic microcapsule pigment)
As component (a), 9-ethyl- (3-methylbutyl) amino-spiro [12H-benzo [a] xanthene-12,1 '(3H) -isobenzofuran] -3'-one 6.0 parts, (b) A reversible color-changing color memory composition consisting of 15.0 parts of 4,4 '-(2-ethylhexylidene) bisphenol as a component and 50.0 parts of 4-benzyloxyphenylethyl caprate as a component (c) was uniformly applied. Was dissolved in the solution by heating, and a solution prepared by mixing 35.0 parts of an aromatic polyvalent isocyanate prepolymer as a wall film material and 50.0 parts of a cosolvent was emulsified and dispersed in an 8% aqueous polyvinyl alcohol solution to form fine droplets. After continuing stirring while heating, 2.5 parts of a water-soluble aliphatic modified amine was added, and stirring was further continued to obtain a microcapsule pigment suspension.
A microcapsule pigment was obtained by filtering the suspension with a filter press.
The volume average particle size of the microcapsule pigment was 1.02 μm, and the maximum particle size was 3.91 μm.
The microcapsule pigment has a complete decolorization temperature of 60 ° C. and a complete color development temperature of −25 ° C., and changes its color from magenta to colorless due to temperature change.

(Preparation of reversible thermochromic ink composition for inkjet)
10.0 parts of the microcapsule pigment (previously cooled and developed), 14.0 parts of morpholinoethyl (meth) acrylate, 10.0 parts of piperazinoethyl (meth) acrylate, 2-hydroxy-3- (4-) Benzoylphenoxy) -N, N, N-trimethyl-1-propaneammonium chloride 1.0 part, ethylene glycol 5.0 parts, antifungal agent (trade name: Proxel XL-2, manufactured by Zeneca Corporation) 0.2 parts , 0.5 parts of a defoaming agent (silicon type, trade name: SN deformer 381, manufactured by San Nopco Co., Ltd.) and 59.3 parts of water were uniformly mixed to prepare a reversible thermochromic ink composition.

(inkjet printer)
Using the inkjet printer used in Example 1, the ink composition was stored in the ink storage portion.

Recording paper (copy paper) was printed and UV light was irradiated using the inkjet printer to obtain a reversible thermochromic printed matter.
During printing, the circulation mechanism was operated to circulate the ink in the ink supply channel, the printer head, and the ink recovery channel.
The reversible thermochromic image of magenta color is visually recognized at room temperature (25 ° C.) on the printed matter, and the reversible thermochromic image is erased by heating to 60 ° C. or higher, and the state before use (magenta color) at −25. The state in which the print of (1) was formed) was returned.
The reversible thermochromic image was formed by setting the decolored recording sheet again in the ink jet printer and printing was performed, and the printed matter could be repeatedly used.

Example 3
(Preparation of reversible thermochromic microcapsule pigment)
As component (a), 9-ethyl- (3-methylbutyl) amino-spiro [12H-benzo [a] xanthene-12,1 '(3H) -isobenzofuran] -3'-one 6.0 parts, (b) A reversible color-changing color memory composition composed of 15.0 parts of 4,4 '-(2-ethylhexylidene) bisphenol as a component and 50.0 parts of 4-benzyloxyphenylethyl caprate as a component (c) is homogeneous. Is dissolved in a solution by heating, and a solution obtained by mixing 40.0 parts of an aromatic polyvalent isocyanate prepolymer as a wall film material and 50.0 parts of a cosolvent is emulsified and dispersed in a 12% polyvinyl alcohol aqueous solution to form fine droplets. After continuing stirring while heating, 2.5 parts of a water-soluble aliphatic modified amine was added, and stirring was further continued to obtain a microcapsule pigment suspension.
A microcapsule pigment was obtained by filtering the suspension with a filter press.
The volume average particle diameter of the microcapsule pigment was 0.55 μm, and the maximum particle diameter was 1.55 μm.
The microcapsule pigment has a complete decolorization temperature of 60 ° C. and a complete color development temperature of −25 ° C., and changes its color from magenta to colorless due to temperature change.

(Preparation of reversible thermochromic ink composition for inkjet)
10.0 parts of the microcapsule pigment (previously cooled and developed), 14.0 parts of morpholinoethyl (meth) acrylate, 10.0 parts of piperazinoethyl (meth) acrylate, 2-hydroxy-3- (4-) Benzoylphenoxy) -N, N, N-trimethyl-1-propaneammonium chloride 1.0 part, ethylene glycol 5.0 parts, antifungal agent (trade name: Proxel XL-2, manufactured by Zeneca Corporation) 0.2 parts , 0.5 parts of a defoaming agent (silicon type, trade name: SN deformer 381, manufactured by San Nopco Co., Ltd.) and 59.3 parts of water were uniformly mixed to prepare a reversible thermochromic ink composition.

(inkjet printer)
Using the inkjet printer used in Example 1, the ink composition was stored in the ink storage portion.

Printing was performed on a recording paper (copy paper) using the above inkjet printer to form a reversible thermochromic image to obtain a reversible thermochromic printed matter.
During printing, the circulation mechanism was operated to flow the ink in the ink flow path and the printer head.
A reversible thermochromic image of magenta color is visually recognized at room temperature (25 ° C.) on the printed matter, and the reversible thermochromic image is erased by heating to 60 ° C. or higher, and a state before use (magenta) at −25 ° C. The state in which color printing was formed) was restored.
The reversible thermochromic image was formed by setting the decolored recording paper in the ink jet printer again and printing was performed, and the printed material could be used repeatedly.

Example 4
(Preparation of reversible thermochromic microcapsule pigment and reversible thermochromic ink composition for inkjet)
A reversible thermochromic ink composition similar to that in Example 1 was prepared.

(inkjet printer)
The ink composition was stored in the inkjet printer used in Example 1.

Recording was performed on a recording paper (coated paper, trade name: Raicho Coat, manufactured by Chuetsu Chemical Industry Co., Ltd.) by using the above inkjet printer to form a reversible thermochromic image to obtain a reversible thermochromic printed matter.
During printing, the circulation mechanism was operated to flow the ink in the ink flow path and the printer head.
A reversible thermochromic image of magenta color is visually recognized at room temperature (25 ° C.) on the printed matter, and the reversible thermochromic image is erased by heating to 60 ° C. or higher, and a state before use (magenta) at −25 ° C. The state in which color printing was formed) was restored.
The reversible thermochromic image was formed by setting the decolored recording sheet again in the ink jet printer and printing was performed, and the printed matter could be repeatedly used.

Example 5
(Preparation of reversible thermochromic microcapsule pigment and reversible thermochromic ink composition for inkjet)
A reversible thermochromic ink composition similar to that in Example 1 was prepared.

(inkjet printer)
Using the inkjet printer used in Example 1, the ink composition was stored in the ink storage portion.

Printing was performed on a recording material (resin plate, thickness 5 mm, made of acrylic resin) using the above inkjet printer to form a reversible thermochromic image to obtain a reversible thermochromic printed matter.
During printing, the circulation mechanism was operated to flow the ink in the ink flow path and the printer head.
A reversible thermochromic image of magenta color is visually recognized at room temperature (25 ° C.) on the printed matter, and the reversible thermochromic image is erased by heating to 60 ° C. or higher, and a state before use (magenta) at −25 ° C. The state in which color printing was formed) was restored.
The reversible thermochromic image was formed by setting the recording material in the ink jet printer again and printing was performed, and the printed material could be repeatedly used.

Example 6
(Preparation of reversible thermochromic microcapsule pigment and reversible thermochromic ink composition for inkjet)
A reversible thermochromic ink composition similar to that in Example 1 was prepared.

(inkjet printer)
Using the inkjet printer used in Example 1, the ink composition was stored in the ink storage portion.

The ink jet printer was used to print on the side wall of a recording material (polypropylene resin bottle) to form a reversible thermochromic image to obtain a reversible thermochromic printed matter.
During printing, the circulation mechanism was operated to flow the ink in the ink flow path and the printer head.
The reversible thermochromic image of magenta color is visually recognized at room temperature (25 ° C) in the printed matter, and the reversible thermochromic image disappears when hot water of 60 ° C or more is poured, and the state immediately after printing (magenta color) at -25 ° C. The state in which the print of (1) was formed) was returned.
The reversible thermochromic image was formed by setting the decolored recording material in the ink jet printer again and printing was performed, and the printed material could be used repeatedly.

Example 7
(Preparation of reversible thermochromic microcapsule pigment)
Preparation of reversible thermochromic microcapsule pigment (a) 7- [2- (acetylamino) -4- (diethylamino) phenyl] -7- (2-methyl-1-propyl-1H-indol-3-yl as component ) Furo [3,4-b] pyridin-5 (7H) -one (3.0 parts), 1,2'-bis (4'-hydroxyphenyl) n-nonane (15.0 parts) as component (b), ), A reversible color-changing color memory composition composed of 50.0 parts of 4-benzyloxyphenylethyl caprate is uniformly dissolved by heating, and 40.0 parts of an aromatic polyisocyanate prepolymer is used as a wall film material. A solution obtained by mixing 50.0 parts of a solvent is emulsified and dispersed in a 10% aqueous solution of polyvinyl alcohol so as to form fine droplets, and after continuing stirring while heating, 2.5 parts of a water-soluble aliphatic modified amine is added. And more The stirring was continued to obtain a microcapsule pigment suspension.
A microcapsule pigment was obtained by filtering the suspension with a filter press.
The volume average particle size of the microcapsule pigment was 0.73 μm, and the maximum particle size was 2.60 μm.
The microcapsule pigment has a complete decolorization temperature of 60 ° C. and a complete color development temperature of −25 ° C., and changes color from cyan to colorless due to temperature change.

(Preparation of reversible thermochromic ink composition for inkjet)
10.0 parts of the microcapsule pigment (previously cooled and developed), 14.0 parts of morpholinoethyl (meth) acrylate, 10.0 parts of piperazinoethyl (meth) acrylate, 2-hydroxy-3- (4-) Benzoylphenoxy) -N, N, N-trimethyl-1-propaneammonium chloride 1.0 part, ethylene glycol 5.0 parts, antifungal agent (trade name: Proxel XL-2, manufactured by Zeneca Corporation) 0.2 parts , 0.5 parts of a defoaming agent (silicon type, trade name: SN deformer 381, manufactured by San Nopco Co., Ltd.) and 59.3 parts of water were uniformly mixed to prepare a reversible thermochromic ink composition.

(inkjet printer)
Using the inkjet printer used in Example 1, the ink composition was stored in the ink storage portion.

Printing was performed on a recording paper (copy paper) using the above inkjet printer to form a reversible thermochromic image to obtain a reversible thermochromic printed matter.
During printing, the circulation mechanism was operated to flow the ink in the ink flow path and the printer head.
A cyan reversible thermochromic image is visually recognized at room temperature (25 ° C.), the reversible thermochromic image is erased by heating at 60 ° C. or higher, and the reprinted thermochromic image is immediately printed at −25 ° C. (cyan). The state in which color printing was formed) was restored.
The reversible thermochromic image was formed by setting the decolored recording sheet again in the ink jet printer and printing was performed, and the printed matter could be repeatedly used.

Example 8
(Preparation of reversible thermochromic microcapsule pigment)
3.0 parts of 4- [2,6-bis (2-ethoxyphenyl) -4-pyridinyl] -N, N-dimethylbenzenamine as the component (a) and 2,2-bis (4- as the component (b). As a wall film material, a reversible color-changing color memory composition comprising 9.0 parts of (hydroxyphenyl) hexafluoropropane and 50.0 parts of 4-benzyloxyphenylethyl caprate as a component (c) is uniformly heated and dissolved. A solution obtained by mixing 40.0 parts of the aromatic polyvalent isocyanate prepolymer and 50.0 parts of the cosolvent was emulsified and dispersed in a 10% aqueous solution of polyvinyl alcohol to form fine droplets, and after stirring while heating. , 2.5 parts of water-soluble aliphatic modified amine was added, and stirring was further continued to obtain a microcapsule pigment suspension.
A microcapsule pigment was obtained by filtering the suspension with a filter press.
The volume average particle size of the microcapsule pigment was 0.70 μm, and the maximum particle size was 2.60 μm.
The microcapsule pigment has a complete decolorization temperature of 60 ° C. and a complete color development temperature of −25 ° C., and changes color from yellow to colorless due to temperature change.

(Preparation of reversible thermochromic ink composition for inkjet)
10.0 parts of the microcapsule pigment (previously cooled and developed), 14.0 parts of morpholinoethyl (meth) acrylate, 10.0 parts of piperazinoethyl (meth) acrylate, 2-hydroxy-3- (4-) Benzoylphenoxy) -N, N, N-trimethyl-1-propaneammonium chloride 1.0 part, ethylene glycol 5.0 parts, antifungal agent (trade name: Proxel XL-2, manufactured by Zeneca Corporation) 0.2 parts , 0.5 parts of a defoaming agent (silicon type, trade name: SN deformer 381, manufactured by San Nopco Co., Ltd.) and 59.3 parts of water were uniformly mixed to prepare a reversible thermochromic ink composition.

(inkjet printer)
Using the inkjet printer used in Example 1, the ink composition was stored in the ink storage portion.

Printing was performed on a recording paper (copy paper) using the above inkjet printer to form a reversible thermochromic image to obtain a reversible thermochromic printed matter.
During printing, the circulation mechanism was operated to flow the ink in the ink flow path and the printer head.
A yellow reversible thermochromic image is visually recognized at room temperature (25 ° C.) on the printed matter, and the reversible thermochromic image is erased by heating to 60 ° C. or higher, and a state immediately after printing (yellow) at −25 ° C. It returned to the state in which the color print image was formed).
The reversible thermochromic image was formed by setting the decolored recording sheet again in the ink jet printer and printing was performed, and the printed matter could be repeatedly used.

Example 9
(Preparation of reversible thermochromic microcapsule pigment)
7.0 parts of 2- (2-chloroanilino) -6-di-n-butylaminofluorane as component (a) and 1,1'-bis (4'-hydroxyphenyl) n-dodecane 15 as component (b) 0.0 parts, and a reversible color-changing color-memory composition composed of 50.0 parts of 4-benzyloxyphenylethyl caprate as a component (c) is uniformly heated and dissolved, and an aromatic polyvalent isocyanate prepolymer is used as a wall film material. A solution prepared by mixing 40.0 parts and 50.0 parts of a cosolvent was emulsified and dispersed in a 10% aqueous solution of polyvinyl alcohol to form fine droplets, and the mixture was stirred while heating, and then water-soluble aliphatically modified amine. 2.5 parts was added and stirring was continued to obtain a microcapsule pigment suspension.
A microcapsule pigment was obtained by filtering the suspension with a filter press.
The volume average particle size of the microcapsule pigment was 0.78 μm, and the maximum particle size was 2.60 μm.
The microcapsule pigment has a complete decolorization temperature of 60 ° C. and a complete color development temperature of −25 ° C., and changes its color from black to colorless due to temperature change.

(Preparation of reversible thermochromic ink composition for inkjet)
10.0 parts of the microcapsule pigment (previously cooled and developed), 14.0 parts of morpholinoethyl (meth) acrylate, 10.0 parts of piperazinoethyl (meth) acrylate, 2-hydroxy-3- (4-) Benzoylphenoxy) -N, N, N-trimethyl-1-propaneammonium chloride 1.0 part, ethylene glycol 5.0 parts, antifungal agent (trade name: Proxel XL-2, manufactured by Zeneca Corporation) 0.2 parts , 0.5 parts of a defoaming agent (silicon type, trade name: SN deformer 381, manufactured by San Nopco Co., Ltd.) and 59.3 parts of water were uniformly mixed to prepare a reversible thermochromic ink composition.

(inkjet printer)
Using the inkjet printer used in Example 1, the ink composition was stored in the ink storage portion.

Recording paper (copy paper) was printed and UV light was irradiated using the inkjet printer to obtain a reversible thermochromic printed matter.
During printing, the circulation mechanism was operated to circulate the ink in the ink supply channel, the printer head, and the ink recovery channel.
A black reversible thermochromic image is visually recognized at room temperature (25 ° C.) on the printed matter, and the reversible thermochromic image is decolored by heating to 60 ° C. or higher, and a state immediately after printing (black) at −25 ° C. The state in which color printing was formed) was restored.
The reversible thermochromic image was formed by setting the decolored recording sheet again in the ink jet printer and printing was performed, and the printed matter could be repeatedly used.

Example 10
(Preparation of reversible thermochromic microcapsule pigment)
As component (a), 9-ethyl- (3-methylbutyl) amino-spiro [12H-benzo [a] xanthene-12,1 '(3H) -isobenzofuran] -3'-one 6.0 parts, (b) 2,2-bis (4-hydroxyphenyl) hexafluoropropane (4.0 parts), 4,4 ′-(2-ethylhexylidene) bisphenol (11.0 parts), (c) component glutaric acid di-4 -A reversible color-changing color memory composition composed of 50.0 parts of benzyloxyphenylethyl was uniformly heated and dissolved, and 40.0 parts of an aromatic polyvalent isocyanate prepolymer and 50.0 parts of a cosolvent were used as a wall film material. The mixed solution was emulsified and dispersed in a 10% aqueous solution of polyvinyl alcohol so as to form fine droplets, and while stirring was continued while heating, 2.5 parts of a water-soluble aliphatic modified amine was added and further stirred. To obtain a microcapsule pigment suspension followed.
A microcapsule pigment was obtained by filtering the suspension with a filter press.
The volume average particle size of the microcapsule pigment was 0.92 μm, and the maximum particle size was 3.52 μm.
The microcapsule pigment has a complete decolorization temperature of 87 ° C. and a complete color development temperature of −35 ° C., and changes from magenta color to colorless due to temperature change.

(Preparation of reversible thermochromic ink composition for inkjet)
10.0 parts of the microcapsule pigment (previously cooled and developed), 14.0 parts of morpholinoethyl (meth) acrylate, 10.0 parts of piperazinoethyl (meth) acrylate, 2-hydroxy-3- (4-) Benzoylphenoxy) -N, N, N-trimethyl-1-propaneammonium chloride 1.0 part, ethylene glycol 5.0 parts, antifungal agent (trade name: Proxel XL-2, manufactured by Zeneca Corporation) 0.2 parts , 0.5 parts of a defoaming agent (silicon type, trade name: SN deformer 381, manufactured by San Nopco Co., Ltd.) and 59.3 parts of water were uniformly mixed to prepare a reversible thermochromic ink composition.

(inkjet printer)
Using the inkjet printer used in Example 1, the ink composition was stored in the ink storage portion.

Recording paper (copy paper) was printed and UV light was irradiated using the inkjet printer to obtain a reversible thermochromic printed matter.
During printing, the circulation mechanism was operated to circulate the ink in the ink supply channel, the printer head, and the ink recovery channel.
The reversible thermochromic image of magenta color is visually recognized at room temperature (25 ° C.) on the printed matter, and the reversible thermochromic image is erased by heating at 87 ° C. or higher, and the state immediately after printing (magenta) at −35 ° C. The state in which color printing was formed) was restored.
The reversible thermochromic image was formed by setting the decolored recording sheet again in the ink jet printer and printing was performed, and the printed matter could be repeatedly used.

Example 11
(Preparation of reversible thermochromic microcapsule pigment)
As component (a), 9-ethyl- (3-methylbutyl) amino-spiro [12H-benzo [a] xanthene-12,1 '(3H) -isobenzofuran] -3'-one 6.0 parts, (b) A reversible color-changing color-memory composition composed of 10.0 parts of 1,1'-bis (4'-hydroxyphenyl) 2-ethylhexane as a component and 50.0 parts of n-nonyl palmitate as a component (c) was homogeneous. Is heated and dissolved in, and a solution obtained by mixing 40.0 parts of an aromatic polyvalent isocyanate prepolymer as a wall film material and 50.0 parts of a cosolvent is emulsified and dispersed in a 10% polyvinyl alcohol aqueous solution to form fine droplets. After continuing stirring while heating, 2.5 parts of a water-soluble aliphatic modified amine was added, and stirring was further continued to obtain a microcapsule pigment suspension.
A microcapsule pigment was obtained by filtering the suspension with a filter press.
The volume average particle diameter of the microcapsule pigment was 1.02 μm, and the maximum particle diameter was 3.72 μm.
The microcapsule pigment has a complete decolorization temperature of 30 ° C. and a complete color development temperature of 18 ° C. The color changes from magenta to colorless due to temperature change.

(Preparation of reversible thermochromic ink composition for inkjet)
10.0 parts of the microcapsule pigment (previously cooled and developed), 14.0 parts of morpholinoethyl (meth) acrylate, 10.0 parts of piperazinoethyl (meth) acrylate, 2-hydroxy-3- (4-) Benzoylphenoxy) -N, N, N-trimethyl-1-propaneammonium chloride 1.0 part, ethylene glycol 5.0 parts, antifungal agent (trade name: Proxel XL-2, manufactured by Zeneca Corporation) 0.2 parts , 0.5 parts of a defoaming agent (silicon type, trade name: SN deformer 381, manufactured by San Nopco Co., Ltd.) and 59.3 parts of water were uniformly mixed to prepare a reversible thermochromic ink composition.

(inkjet printer)
Using the inkjet printer used in Example 1, the ink composition was stored in the ink storage portion.

Recording paper (copy paper) was printed and UV light was irradiated using the inkjet printer to obtain a reversible thermochromic printed matter.
During printing, the circulation mechanism was operated to circulate the ink in the ink supply channel, the printer head, and the ink recovery channel.
The reversible thermochromic image of magenta color is visually recognized at room temperature (25 ° C.) on the printed matter, and the reversible thermochromic image disappears by heating at 30 ° C. or higher, and the state immediately after printing at 18 ° C. (magenta color) The state in which the print characters of (1) have been formed) has been restored.
The reversible thermochromic image was formed by setting the decolored recording sheet again in the ink jet printer and printing was performed, and the printed matter could be repeatedly used.

Example 12
(Preparation of reversible thermochromic microcapsule pigment)
As component (a), 9-ethyl- (3-methylbutyl) amino-spiro [12H-benzo [a] xanthene-12,1 '(3H) -isobenzofuran] -3'-one 6.0 parts, (b) A reversible color-changing color memory composition comprising 10.0 parts of 1,1'-bis (4'-hydroxyphenyl) 2-ethylhexane as a component and 50.0 parts of 4-methylbenzyl laurate as a component (c). Emulsion dispersion of a solution prepared by uniformly heating and dissolving, and mixing 40.0 parts of aromatic polyvalent isocyanate prepolymer as a wall film material and 50.0 parts of cosolvent in a 10% polyvinyl alcohol aqueous solution to form fine droplets. After continuing stirring while heating, 2.5 parts of a water-soluble aliphatic modified amine was added, and stirring was further continued to obtain a microcapsule pigment suspension.
A microcapsule pigment was obtained by filtering the suspension with a filter press.
The volume average particle diameter of the microcapsule pigment was 0.87 μm, and the maximum particle diameter was 2.57 μm.
The microcapsule pigment has a complete decolorization temperature of 27 ° C. and a complete color development temperature of −25 ° C., and changes from magenta color to colorless due to temperature change.

(Preparation of reversible thermochromic ink composition for inkjet)
10.0 parts of the microcapsule pigment (previously cooled and developed), 14.0 parts of morpholinoethyl (meth) acrylate, 10.0 parts of piperazinoethyl (meth) acrylate, 2-hydroxy-3- (4-) Benzoylphenoxy) -N, N, N-trimethyl-1-propaneammonium chloride 1.0 part, ethylene glycol 5.0 parts, antifungal agent (trade name: Proxel XL-2, manufactured by Zeneca Corporation) 0.2 parts , 0.5 parts of a defoaming agent (silicon type, trade name: SN deformer 381, manufactured by San Nopco Co., Ltd.) and 59.3 parts of water were uniformly mixed to prepare a reversible thermochromic ink composition.

(inkjet printer)
Using the inkjet printer used in Example 1, the ink composition was stored in the ink storage portion.

Recording paper (copy paper) was printed and UV light was irradiated using the inkjet printer to obtain a reversible thermochromic printed matter.
During printing, the circulation mechanism was operated to circulate the ink in the ink supply channel, the printer head, and the ink recovery channel.
The reversible thermochromic image of magenta color is visually recognized at room temperature (25 ° C.) on the printed matter, and the reversible thermochromic image is erased by heating at 27 ° C. or higher, and the state immediately after printing (magenta) at -25 ° C. It returned to the state in which color print characters were formed).
The reversible thermochromic image was formed by setting the decolored recording sheet again in the ink jet printer and printing was performed, and the printed matter could be repeatedly used.

Example 13
(Preparation of reversible thermochromic microcapsule pigment)
The same reversible thermochromic microcapsule pigment as in Example 1 was prepared.

(Preparation of reversible thermochromic ink composition for inkjet)
10.0 parts of the microcapsule pigment (pre-cooled and developed color), 0.2 part of organic pigment (Pigment Blue 15: 3), 14.0 parts of morpholinoethyl (meth) acrylate, piperazinoethyl (meth) acrylate 10.0 parts, 2-hydroxy-3- (4-benzoylphenoxy) -N, N, N-trimethyl-1-propanammonium chloride 1.0 part, ethylene glycol 5.0 parts, antifungal agent (trade name: 0.2 parts of Proxel XL-2, manufactured by Zeneca Co., Ltd., 0.5 part of an antifoaming agent (silicon type, trade name: SN deformer 381, manufactured by San Nopco Co., Ltd.), and 59.1 parts of water are uniformly mixed. A reversible thermochromic ink composition was prepared.

(inkjet printer)
Using the inkjet printer used in Example 1, the ink composition was stored in the ink storage portion.

Recording paper (copy paper) was printed and UV light was irradiated using the inkjet printer to obtain a reversible thermochromic printed matter.
During printing, the circulation mechanism was operated to circulate the ink in the ink supply channel, the printer head, and the ink recovery channel.
A purple reversible thermochromic image is visually recognized at room temperature (25 ° C.) in the printed matter, and the reversible thermochromic image is changed to cyan by heating at 60 ° C. or higher, and a state immediately after printing at −25 ° C. ( It returned to the state where the purple print was formed).

Example 14
(Preparation of reversible thermochromic microcapsule pigment)
Preparation of reversible thermochromic microcapsule pigment A (a) 7- [2- (acetylamino) -4- (diethylamino) phenyl] -7- (2-methyl-1-propyl-1H-indole-3-) Yl) furo [3,4-b] pyridin-5 (7H) -one 3.0 parts, as component (b) 4,4 '-(2-ethylhexylidene) bisphenol 15.0 parts, (c) A reversible color-changing color-memory composition composed of 50.0 parts of 4-benzyloxyphenylethyl caprate as a component is uniformly dissolved by heating, and 40.0 parts of an aromatic polyvalent isocyanate prepolymer as a wall film material and a cosolvent. A solution obtained by mixing 50.0 parts was emulsified and dispersed in a 10% aqueous solution of polyvinyl alcohol so as to form fine droplets, and stirring was continued while heating, and then 2.5 parts of a water-soluble aliphatic modified amine was added, Further The stirring was continued to obtain a microcapsule pigment suspension. Microcapsule pigment A was obtained by filtering the suspension with a filter press.
The volume average particle size of the microcapsule pigment A was 0.69 μm, and the maximum particle size was 2.27 μm.
The complete decolorization temperature of the microcapsule pigment A is 60 ° C. and the complete color development temperature is −25 ° C., and the cyan color changes to colorless due to temperature change.
Preparation of reversible thermochromic microcapsule pigment B (a) 9-ethyl- (3-methylbutyl) amino-spiro [12H-benzo [a] xanthene-12,1 '(3H) -isobenzofuran] -3' as component Reversible color change consisting of 6.0 parts of -one, 10.0 parts of (4) component, 4,4 '-(2-ethylhexylidene) bisphenol, and 50.0 parts of 4-methylbenzyl palmitate as (C) component. A color-memory composition was uniformly heated and dissolved, and a solution prepared by mixing 40.0 parts of an aromatic polyvalent isocyanate prepolymer and 50.0 parts of a cosolvent as a wall film material was dissolved in a 10% polyvinyl alcohol aqueous solution to give a fine solution The mixture was emulsified and dispersed in the form of drops, and stirring was continued while heating, 2.5 parts of a water-soluble aliphatic modified amine was added, and the stirring was further continued to obtain a microcapsule pigment suspension.
Microcapsule pigment B was obtained by filtering the suspension with a filter press.
The volume average particle size of the microcapsule pigment B was 0.73 μm, and the maximum particle size was 2.60 μm.
The complete decolorization temperature of the microcapsule pigment B is 40 ° C. and the complete color development temperature is 5 ° C. The color change from magenta to colorless due to temperature change.

(Preparation of reversible thermochromic ink composition for inkjet)
5.0 parts of the microcapsule pigment A (pre-cooled and developed color), 5.0 parts of the microcapsule pigment B (pre-cooled and developed color), morpholinoethyl (meth) acrylate 14.0 Parts, piperazinoethyl (meth) acrylate 10.0 parts, 2-hydroxy-3- (4-benzoylphenoxy) -N, N, N-trimethyl-1-propaneammonium chloride 1.0 part, ethylene glycol 5.0 parts, Antifungal agent (trade name: Proxel XL-2, manufactured by Zeneca Co., Ltd.) 0.2 part, antifoaming agent (silicon type, trade name: SN Deformer 381, manufactured by San Nopco Co., Ltd.) 0.5 part, and water 59. A reversible thermochromic ink composition was prepared by uniformly mixing 3 parts.

(inkjet printer)
Using the inkjet printer used in Example 1, the ink composition was stored in the ink storage portion.

Recording paper (copy paper) was printed and UV light was irradiated using the inkjet printer to obtain a reversible thermochromic printed matter.
During printing, the circulation mechanism was operated to circulate the ink in the ink supply channel, the printer head, and the ink recovery channel.
A purple reversible thermochromic image is visually recognized at room temperature (25 ° C.), and the reversible thermochromic image changes to cyan when heated to 40 ° C. or higher, and reversible when heated to 60 ° C. or higher. The thermochromic image disappeared, and the reversible thermochromic image changed to magenta at -5 ° C and returned to the state immediately after printing (state where purple print was formed) at -25 ° C.
The reversible thermochromic image was formed by setting the decolored recording sheet again in the ink jet printer and printing was performed, and the printed matter could be repeatedly used.

Example 15
(Preparation of reversible thermochromic microcapsule pigment)
Preparation of reversible thermochromic microcapsule pigment (a) As component 9-ethyl- (3-methylbutyl) amino-spiro [12H-benzo [a] xanthene-12,1 '(3H) -isobenzofuran] -3'- ON 4.5 parts, 2,2-bis (4-hydroxyphenyl) hexafluoropropane 4.0 parts as component (B), 4,4 '-(2-ethylhexylidene) bisphenol 4.0 parts, ( C) As a component, a reversible color-changing color-memory composition composed of 32.5 parts of stearyl caprate and 17.5 parts of stearyl laurate is uniformly heated and dissolved, and as a wall film material, an aromatic polyvalent isocyanate prepolymer 40. A solution prepared by mixing 0 part and 50.0 parts of a cosolvent was emulsified and dispersed in a 10% aqueous solution of polyvinyl alcohol to form fine droplets, and the mixture was stirred while heating, and then water-soluble. 2.5 parts of a modified aliphatic aliphatic amine was added and stirring was continued to obtain a microcapsule pigment suspension.
A microcapsule pigment was obtained by filtering the suspension with a filter press.
The volume average particle size of the microcapsule pigment was 0.85 μm, and the maximum particle size was 2.85 μm.
The complete decolorization temperature of the microcapsule pigment is 37 ° C. and the complete color development temperature is 28 ° C. The color changes from magenta to colorless due to temperature change.

(Preparation of reversible thermochromic ink composition for inkjet)
10.0 parts of the microcapsule pigment, 14.0 parts of morpholinoethyl (meth) acrylate, 10.0 parts of piperazinoethyl (meth) acrylate, 2-hydroxy-3- (4-benzoylphenoxy) -N, N, N- Trimethyl-1-propane ammonium chloride 1.0 part, ethylene glycol 5.0 parts, antifungal agent (trade name: Proxel XL-2, manufactured by Zeneca Corporation) 0.2 part, defoaming agent (silicon type, trade name) : SN deformer 381, manufactured by San Nopco Ltd.) and 0.5 parts of water were uniformly mixed to prepare a reversible thermochromic ink composition.

(Ink container)
The ink composition was contained in an ink bottle having the same form as the ink container used in Example 1.

(inkjet printer)
Using the inkjet printer used in Example 1, the ink composition was stored in the ink storage portion.

Recording paper (copy paper) was printed and UV light was irradiated using the inkjet printer to obtain a reversible thermochromic printed matter.
During printing, the circulation mechanism was operated to circulate the ink in the ink supply channel, the printer head, and the ink recovery channel.
The reversible thermochromic image of magenta color is visually recognized at room temperature (25 ° C) on the printed matter, and the reversible thermochromic image is erased by heating at 37 ° C or higher, and immediately after printing at room temperature (25 ° C). (The state in which a magenta color print image is formed).

Example 16
(Preparation of reversible thermochromic microcapsule pigment)
Preparation of reversible thermochromic microcapsule pigment (a) 3 ', 6'-bis [phenyl (3-methylphenyl) amino] -spiro [isobenzofuran-1 (3H), 9'-(9H) xanthene] as component -3-one 3.0 parts, (b) component 4,4 '-(2-methylpropylidene) bisphenol 8.0 parts, (c) component 2-methylpentyl stearate 15.0 parts, stearic acid A reversible color-changing color-memory composition composed of 35.0 parts of 2-ethylhexyl was uniformly heated and dissolved, and 40.0 parts of an aromatic polyvalent isocyanate prepolymer as a wall film material and 50.0 parts of a cosolvent were mixed. The solution was emulsified and dispersed in a 10% aqueous solution of polyvinyl alcohol to form fine droplets, and the mixture was continuously stirred while heating, then 2.5 parts of a water-soluble aliphatic modified amine was added, and the mixture was further stirred. A microcapsule pigment suspension was obtained.
A microcapsule pigment was obtained by filtering the suspension with a filter press.
The volume average particle size of the microcapsule pigment was 0.85 μm, and the maximum particle size was 2.85 μm.
The complete decolorization temperature of the microcapsule pigment is 10 ° C and the complete color development temperature is 5 ° C, and the color changes from blue to colorless due to temperature change.

(Preparation of reversible thermochromic ink composition for inkjet)
10.0 parts of the microcapsule pigment, 14.0 parts of morpholinoethyl (meth) acrylate, 10.0 parts of piperazinoethyl (meth) acrylate, 2-hydroxy-3- (4-benzoylphenoxy) -N, N, N- Trimethyl-1-propane ammonium chloride 1.0 part, ethylene glycol 5.0 parts, antifungal agent (trade name: Proxel XL-2, manufactured by Zeneca Corporation) 0.2 part, defoaming agent (silicon type, trade name) : SN deformer 381, manufactured by San Nopco Ltd.) and 0.5 parts of water were uniformly mixed to prepare a reversible thermochromic ink composition.

(Ink container)
The ink composition was contained in an ink bottle having the same form as the ink container used in Example 1.

(inkjet printer)
Using the inkjet printer used in Example 1, the ink composition was stored in the ink storage portion.

Recording paper (copy paper) was printed and UV light was irradiated using the inkjet printer to obtain a reversible thermochromic printed matter.
During printing, the circulation mechanism was operated to circulate the ink in the ink supply channel, the printer head, and the ink recovery channel.
The reversible thermochromic image of the printed matter is in a decolored state at room temperature (25 ° C), and when cooled to 5 ° C or less, a blue reversible thermochromic image is visually recognized and heated to 10 ° C or more. As a result, the reversible thermochromic image returned to a decolored state.

Example 17
(Preparation of reversible thermochromic microcapsule pigment)
Preparation of reversible thermochromic microcapsule pigment (a) 3 ', 6'-bis [phenyl (3-methylphenyl) amino] -spiro [isobenzofuran-1 (3H), 9'-(9H) xanthene] as component -3-one 3.0 parts, (b) component 4,4 '-(2-methylpropylidene) bisphenol 8.0 parts, (c) component n-nonyl palmitate 30.0 parts, decyl myristate A solution prepared by uniformly heating and dissolving a reversible color-changing color memory composition of 20.0 parts and mixing 40.0 parts of an aromatic polyvalent isocyanate prepolymer as a wall film material and 50.0 parts of a cosolvent, Emulsify and disperse into 10% polyvinyl alcohol aqueous solution to form fine droplets, continue stirring while heating, add 2.5 parts of water-soluble aliphatic modified amine, and continue stirring to continue microcapsule face A liquid suspension was obtained.
A microcapsule pigment was obtained by filtering the suspension with a filter press.
The volume average particle size of the microcapsule pigment was 0.83 μm, and the maximum particle size was 2.81 μm.
The complete decolorization temperature of the microcapsule pigment is 20 ° C. and the complete color development temperature is 15 ° C., and the color changes from blue to colorless due to temperature change.

(Preparation of reversible thermochromic ink composition for inkjet)
10.0 parts of the microcapsule pigment, 14.0 parts of morpholinoethyl (meth) acrylate, 10.0 parts of piperazinoethyl (meth) acrylate, 2-hydroxy-3- (4-benzoylphenoxy) -N, N, N- Trimethyl-1-propane ammonium chloride 1.0 part, ethylene glycol 5.0 parts, antifungal agent (trade name: Proxel XL-2, manufactured by Zeneca Corporation) 0.2 part, defoaming agent (silicon type, trade name) : SN deformer 381, manufactured by San Nopco Ltd.) and 0.5 parts of water were uniformly mixed to prepare a reversible thermochromic ink composition.

(Ink container)
The ink composition was contained in an ink bottle having the same form as the ink container used in Example 1.

(inkjet printer)
Using the inkjet printer used in Example 1, the ink composition was stored in the ink storage portion.

Recording paper (copy paper) was printed and UV light was irradiated using the inkjet printer to obtain a reversible thermochromic printed matter.
During printing, the circulation mechanism was operated to circulate the ink in the ink supply channel, the printer head, and the ink recovery channel.
The reversible thermochromic image of the printed matter is in a decolored state at room temperature (25 ° C), and when cooled to 15 ° C or less, a blue reversible thermochromic image is visually recognized and heated to 20 ° C or more. As a result, the reversible thermochromic image returned to a decolored state.

Example 18
(Preparation of reversible thermochromic microcapsule pigment)
Preparation of reversible thermochromic microcapsule pigment (a) 3 ', 6'-bis [phenyl (3-methylphenyl) amino] -spiro [isobenzofuran-1 (3H), 9'-(9H) xanthene] as component 3.0 parts of 3--3-one, 8.0 parts of 4,4 '-(2-methylpropylidene) bisphenol as the component (b), 37.5 parts of stearyl caprate as the component (c), cetyl caprate 12. A reversible color-changing color-memory composition consisting of 5 parts was uniformly heated and dissolved, and a solution prepared by mixing 40.0 parts of an aromatic polyvalent isocyanate prepolymer as a wall film material and 50.0 parts of a cosolvent was added with 10%. Emulsify and disperse into minute droplets in a polyvinyl alcohol aqueous solution, continue stirring while heating, add 2.5 parts of water-soluble aliphatic modified amine, and continue stirring to further suspend the microcapsule pigment. A suspension was obtained.
A microcapsule pigment was obtained by filtering the suspension with a filter press.
The volume average particle diameter of the microcapsule pigment was 0.91 μm, and the maximum particle diameter was 3.01 μm.
The complete decolorization temperature of the microcapsule pigment is 30 ° C. and the complete color development temperature is 25 ° C., and the color changes from blue to colorless due to temperature change.

  10.0 parts of the microcapsule pigment, 14.0 parts of morpholinoethyl (meth) acrylate, 10.0 parts of piperazinoethyl (meth) acrylate, 2-hydroxy-3- (4-benzoylphenoxy) -N, N, N- Trimethyl-1-propane ammonium chloride 1.0 part, ethylene glycol 5.0 parts, antifungal agent (trade name: Proxel XL-2, manufactured by Zeneca Corporation) 0.2 part, defoaming agent (silicon-based, trade name) : SN deformer 381, manufactured by San Nopco Ltd.) and 0.5 parts of water were uniformly mixed to prepare a reversible thermochromic ink composition.

(Ink container)
The ink composition was contained in an ink bottle having the same form as the ink container used in Example 1.

(inkjet printer)
Using the inkjet printer used in Example 1, the ink composition was stored in the ink storage portion.

Recording paper (copy paper) was printed and UV light was irradiated using the inkjet printer to obtain a reversible thermochromic printed matter.
During printing, the circulation mechanism was operated to circulate the ink in the ink supply channel, the printer head, and the ink recovery channel.
A blue reversible thermochromic image is visually recognized at room temperature (25 ° C) on the printed matter, and the reversible thermochromic image disappears when heated to 30 ° C or higher, and a state immediately after printing at room temperature (25 ° C) ( It returned to the state in which blue print characters were formed).

Example 19
(Preparation of reversible thermochromic microcapsule pigment)
Preparation of reversible thermochromic microcapsule pigment (a) 3 ', 6'-bis [phenyl (3-methylphenyl) amino] -spiro [isobenzofuran-1 (3H), 9'-(9H) xanthene] as component -3-one 3.0 parts, (b) component 4,4 '-(2-methylpropylidene) bisphenol 8.0 parts, (c) component 3-methylbutyl behenate 25.0 parts, behenic acid 2 A reversible color-changing color-memory composition composed of 25.0 parts of methylpentyl was uniformly heated and dissolved, and 40.0 parts of an aromatic polyvalent isocyanate prepolymer as a wall film material and 50.0 parts of a cosolvent were mixed. The solution was emulsified and dispersed in a 10% aqueous solution of polyvinyl alcohol so as to form fine droplets, and the mixture was stirred while heating, then 2.5 parts of a water-soluble aliphatic modified amine was added, and the mixture was further stirred and micro-sized. A capsule pigment suspension was obtained.
A microcapsule pigment was obtained by filtering the suspension with a filter press.
The volume average particle diameter of the microcapsule pigment was 0.94 μm, and the maximum particle diameter was 3.15 μm.
The complete decolorization temperature of the microcapsule pigment is 40 ° C. and the complete color development temperature is 35 ° C., and the color changes from blue to colorless due to temperature change.

(Preparation of reversible thermochromic ink composition for inkjet)
10.0 parts of the microcapsule pigment, 14.0 parts of morpholinoethyl (meth) acrylate, 10.0 parts of piperazinoethyl (meth) acrylate, 2-hydroxy-3- (4-benzoylphenoxy) -N, N, N- Trimethyl-1-propane ammonium chloride 1.0 part, ethylene glycol 5.0 parts, antifungal agent (trade name: Proxel XL-2, manufactured by Zeneca Corporation) 0.2 part, defoaming agent (silicon type, trade name) : SN deformer 381, manufactured by San Nopco Ltd.) and 0.5 parts of water were uniformly mixed to prepare a reversible thermochromic ink composition.

(Ink container)
The ink composition was contained in an ink bottle having the same form as the ink container used in Example 1.

(inkjet printer)
Using the inkjet printer used in Example 1, the ink composition was stored in the ink storage portion.

Recording paper (copy paper) was printed and UV light was irradiated using the inkjet printer to obtain a reversible thermochromic printed matter.
During printing, the circulation mechanism was operated to circulate the ink in the ink supply channel, the printer head, and the ink recovery channel.
A blue reversible thermochromic image is visually recognized at room temperature (25 ° C.) on the printed matter, and the reversible thermochromic image disappears when heated to 40 ° C. or higher, and a state immediately after printing at room temperature (25 ° C.) ( It returned to the state in which blue print characters were formed).

Example 20
(Preparation of reversible thermochromic microcapsule pigment)
Preparation of reversible thermochromic microcapsule pigment (a) 3 ', 6'-bis [phenyl (3-methylphenyl) amino] -spiro [isobenzofuran-1 (3H), 9'-(9H) xanthene] as component -3-one 3.0 parts, (b) component 4,4 '-(2-methylpropylidene) bisphenol 8.0 parts, (c) component n-butyl myristate 45.0 parts, palmitic acid n A solution obtained by uniformly heating and dissolving a reversible color-changing color memory composition comprising 5.0 parts of butyl and mixing 40.0 parts of an aromatic polyvalent isocyanate prepolymer as a wall film material and 50.0 parts of a cosolvent. Is emulsified and dispersed in a 10% aqueous solution of polyvinyl alcohol so as to form microdroplets, and while continuing stirring while heating, 2.5 parts of a water-soluble aliphatic modified amine is added, and further stirring is continued to form microcapsules. A pigment suspension was obtained.
A microcapsule pigment was obtained by filtering the suspension with a filter press.
The volume average particle size of the microcapsule pigment was 0.89 μm, and the maximum particle size was 2.93 μm.
The complete decolorization temperature of the microcapsule pigment is 0 ° C. and the complete color development temperature is −15 ° C., and the color changes from blue to colorless due to temperature change.

(Preparation of reversible thermochromic ink composition for inkjet)
10.0 parts of the microcapsule pigment, 14.0 parts of morpholinoethyl (meth) acrylate, 10.0 parts of piperazinoethyl (meth) acrylate, 2-hydroxy-3- (4-benzoylphenoxy) -N, N, N- Trimethyl-1-propane ammonium chloride 1.0 part, ethylene glycol 5.0 parts, antifungal agent (trade name: Proxel XL-2, manufactured by Zeneca Corporation) 0.2 part, defoaming agent (silicon type, trade name) : SN deformer 381, manufactured by San Nopco Ltd.) and 0.5 parts of water were uniformly mixed to prepare a reversible thermochromic ink composition.

(Ink container)
The ink composition was contained in an ink bottle having the same form as the ink container used in Example 1.

(inkjet printer)
Using the inkjet printer used in Example 1, the ink composition was stored in the ink storage portion.

Recording paper (copy paper) was printed and UV light was irradiated using the inkjet printer to obtain a reversible thermochromic printed matter.
During printing, the circulation mechanism was operated to circulate the ink in the ink supply channel, the printer head, and the ink recovery channel.
The reversible thermochromic image of the printed matter is in a decolored state at room temperature (25 ° C.), and when cooled to −15 ° C. or less, a blue reversible thermochromic image is visually recognized and heated to 0 ° C. or higher. As a result, the reversible thermochromic image returned to a decolored state.

  Example 21

(Preparation of reversible thermochromic microcapsule pigment and reversible thermochromic ink composition for inkjet)
Magenta, cyan, yellow, and black reversible thermochromic ink compositions similar to those in Example 1, Example 7, Example 8, and Example 9 were prepared.

(Ink container)
The ink composition was contained in an ink bottle of the same form as the ink container used in Example 1 to prepare an ink bottle set consisting of cyan, magenta, yellow, and black ink bottles.

(inkjet printer)
The ink accommodating portion of the inkjet printer used in Example 1 was made to be capable of accommodating the four color ink compositions independently, and the ink accommodating portion accommodated each color independently.

Printing and UV light irradiation were performed on recording paper (copy paper) using the above inkjet printer to form a reversible thermochromic image to obtain a reversible thermochromic printed matter.
During printing, the circulation mechanism was operated to circulate the ink in the ink supply channel, the printer head, and the ink recovery channel.
At room temperature (25 ° C.), a reversible thermochromic image of a mixed color consisting of magenta, cyan, yellow, black, and two or more colors selected from the above four colors is visually recognized and the printed matter is heated to 60 ° C. or more. As a result, the reversible thermochromic image was erased and returned to the state immediately after printing (the state in which prints of cyan, magenta, yellow, black, etc. were formed) at -25 ° C.
The reversible thermochromic image was formed by setting the decolored recording sheet again in the ink jet printer and printing was performed, and the printed matter could be repeatedly used.

Example 22
(Preparation of reversible thermochromic microcapsule pigment and reversible thermochromic ink composition for inkjet)
Reversible thermochromic ink compositions similar to those in Example 16, Example 17, Example 18, and Example 19 were prepared.

(Ink container)
The above-mentioned four ink compositions were contained in an ink bottle having the same form as the ink container used in Example 1 to prepare an ink bottle set including each ink bottle.

(inkjet printer)
The ink storage portion of the ink jet printer used in Example 1 was made to be able to store the above-mentioned four ink compositions independently, and each ink composition was stored independently in the ink storage portion.

After printing on the recording paper (copy paper) so that each of the ink compositions is recorded at different positions using the above inkjet printer, the printing portion is irradiated with UV light to form a reversible thermochromic image. Thus, a reversible thermochromic printed matter was obtained.
During printing, the circulation mechanism was operated to circulate the ink in the ink supply channel, the printer head, and the ink recovery channel.
The printed matter was printed at room temperature (25 ° C.) with the ink compositions of Example 16 and Example 17 in a decolored state, and the prints formed with the ink compositions of Example 18 and Example 19 were printed. Was visually confirmed, and it was confirmed that it played a role of a temperature indicator.

Example 23
(Preparation of reversible thermochromic microcapsule pigment)
As component (a), 9-ethyl- (3-methylbutyl) amino-spiro [12H-benzo [a] xanthene-12,1 '(3H) -isobenzofuran] -3'-one 6.0 parts, (b) A reversible color-changing color memory composition consisting of 15.0 parts of 4,4 '-(2-ethylhexylidene) bisphenol as a component and 50.0 parts of 4-benzyloxyphenylethyl caprate as a component (c) was uniformly applied. Was dissolved in the solution by heating, and a solution prepared by mixing 35.0 parts of an aromatic polyvalent isocyanate prepolymer as a wall film material and 50.0 parts of a cosolvent was emulsified and dispersed in an 8% aqueous polyvinyl alcohol solution to form fine droplets. After continuing stirring while heating, 2.5 parts of a water-soluble aliphatic modified amine was added, and stirring was further continued to obtain a microcapsule pigment suspension.
A microcapsule pigment was obtained by filtering the suspension with a filter press.
The volume average particle size of the microcapsule pigment was 5.26 μm, and the maximum particle size was 7.69 μm.
The microcapsule pigment has a complete decolorization temperature of 60 ° C. and a complete color development temperature of −25 ° C., and changes its color from magenta to colorless due to temperature change.
The zeta potential of a 10% by mass aqueous dispersion of the microcapsule pigment was 6.3 mV under the conditions of 20.0 ° C and pH 5.2.

(Preparation of reversible thermochromic ink composition for inkjet)
10.0 parts of the microcapsule pigment (previously cooled and developed), 14.0 parts of morpholinoethyl (meth) acrylate, 10.0 parts of piperazinoethyl (meth) acrylate, 2-hydroxy-3- (4-) Benzoylphenoxy) -N, N, N-trimethyl-1-propaneammonium chloride 1.0 part, acrylic polymer dispersant (trade name: Sols Perth 43000, manufactured by Nippon Luvsol Co., Ltd.) 0.5 part, ethylene glycol 5. 0 part, antifungal agent (trade name: Proxel XL-2, manufactured by Zeneca Co., Ltd.) 0.2 part, antifoaming agent (silicon type, trade name: SN Deformer 381, manufactured by San Nopco Co., Ltd.) 0.5 part, and 58.8 parts of water were uniformly mixed to prepare a reversible thermochromic ink composition.

(inkjet printer)
Using the inkjet printer used in Example 1, the ink composition was stored in the ink storage portion.

Recording paper (copy paper) was printed and UV light was irradiated using the inkjet printer to obtain a reversible thermochromic printed matter.
During printing, the circulation mechanism was operated to circulate the ink in the ink supply channel, the printer head, and the ink recovery channel.
The reversible thermochromic image of magenta color is visually recognized at room temperature (25 ° C.) on the printed matter, and the reversible thermochromic image is erased by heating to 60 ° C. or higher, and the state before use (magenta) at −25 ° C. It returned to the state in which color print characters were formed).
The reversible thermochromic image was formed by setting the decolored recording sheet again in the ink jet printer and printing was performed, and the printed matter could be repeatedly used.

Comparative Example 1
Preparation of reversible thermochromic microcapsule pigment (a) 3 ', 6'-bis [phenyl (3-methylphenyl) amino] -spiro [isobenzofuran-1 (3H), 9'-(9H) xanthene] as component -3-one 3.0 parts, (b) component 4,4 '-(2-ethylhexylidene) bisphenol 15.0 parts, (c) component 4-benzyloxyphenylethyl caprate 50.0 parts The reversible color-changing color memory composition consisting of 8% polyvinyl alcohol was mixed with 40.0 parts of an aromatic polyvalent isocyanate prepolymer as a wall film material and 50.0 parts of a cosolvent as a wall film material. After emulsifying and dispersing in an aqueous solution to form microdroplets and continuing stirring while heating, 2.5 parts of a water-soluble aliphatic modified amine is added, and further stirring is continued to prepare a microcapsule pigment suspension. Obtained.
A microcapsule pigment was obtained by filtering the suspension with a filter press.
The volume average particle size of the microcapsule pigment was 6.0 μm, and the maximum particle size was 9.21 μm.
The microcapsule pigment has a complete decolorization temperature of 60 ° C. and a complete color development temperature of −25 ° C., and changes its color from magenta to colorless due to temperature change.

(Preparation of reversible thermochromic ink composition for inkjet)
10.0 parts of the microcapsule pigment (previously cooled and developed), 14.0 parts of morpholinoethyl (meth) acrylate, 10.0 parts of piperazinoethyl (meth) acrylate, 2-hydroxy-3- (4-) Benzoylphenoxy) -N, N, N-trimethyl-1-propaneammonium chloride 1.0 part, ethylene glycol 5.0 parts, antifungal agent (trade name: Proxel XL-2, manufactured by Zeneca Corporation) 0.2 parts , 0.5 parts of a defoaming agent (silicon type, trade name: SN deformer 381, manufactured by San Nopco Co., Ltd.) and 59.3 parts of water were uniformly mixed to prepare a reversible thermochromic ink composition.

(inkjet printer)
The ink composition was stored in the ink storage portion of the inkjet printer used in Example 1. At that time, since an aggregate of the microcapsule pigment was confirmed on the inner bottom of the accommodating portion, printing was not performed.

Comparative example 2
Preparation of reversible thermochromic microcapsule pigment (a) 3 ', 6'-bis [phenyl (3-methylphenyl) amino] -spiro [isobenzofuran-1 (3H), 9'-(9H) xanthene] as component -3-one 3.0 parts, (b) component 4,4 '-(2-ethylhexylidene) bisphenol 15.0 parts, (c) component 4-benzyloxyphenylethyl caprate 50.0 parts The reversible color-changing color memory composition consisting of is uniformly dissolved by heating, and a solution prepared by mixing 40.0 parts of an aromatic polyvalent isocyanate prepolymer as a wall film material and 50.0 parts of a cosolvent is prepared with After emulsifying and dispersing in an aqueous solution to form fine droplets, stirring is continued while heating, 2.5 parts of water-soluble aliphatic modified amine is added, and the stirring is further continued to obtain a microcapsule pigment suspension. Got
A microcapsule pigment was obtained by filtering the suspension with a filter press.
The volume average particle diameter of the microcapsule pigment was 0.05 μm, and the maximum particle diameter was 0.61 μm.
The microcapsule pigment has a complete decolorization temperature of 60 ° C. and a complete color development temperature of −25 ° C., and changes its color from magenta to colorless due to temperature change.

(Preparation of reversible thermochromic ink composition for inkjet)
10.0 parts of the microcapsule pigment (previously cooled and developed), 14.0 parts of morpholinoethyl (meth) acrylate, 10.0 parts of piperazinoethyl (meth) acrylate, 2-hydroxy-3- (4-) Benzoylphenoxy) -N, N, N-trimethyl-1-propaneammonium chloride 1.0 part, ethylene glycol 5.0 parts, antifungal agent (trade name: Proxel XL-2, manufactured by Zeneca Corporation) 0.2 parts , 0.5 parts of a defoaming agent (silicon type, trade name: SN deformer 381, manufactured by San Nopco Co., Ltd.) and 59.3 parts of water were uniformly mixed to prepare a reversible thermochromic ink composition.

(inkjet printer)
The above ink composition was housed in the inkjet printer used in Example 1.

Recording paper (copy paper) was printed and UV light was irradiated using the inkjet printer to obtain a reversible thermochromic printed matter.
During printing, the circulation mechanism was operated to circulate the ink in the ink supply channel, the printer head, and the ink recovery channel.
The reversible thermochromic image of magenta color is visually recognized at room temperature (25 ° C.) in the printed matter, and the reversible thermochromic image is erased by heating to 60 ° C. or higher, and the state immediately after printing (magenta) is obtained at −25 ° C. The state in which color printing was formed) was restored.
Again, the reversible thermochromic image was formed by setting the decolored recording paper in the ink jet printer and printing, and a printed matter could be obtained, and the recording paper could be used repeatedly.

Comparative Example 3
Preparation of reversible thermochromic microcapsule pigment (a) 3 ', 6'-bis [phenyl (3-methylphenyl) amino] -spiro [isobenzofuran-1 (3H), 9'-(9H) xanthene] as component -3-one 3.0 parts, (b) component 4,4 '-(2-ethylhexylidene) bisphenol 15.0 parts, (c) component 4-benzyloxyphenylethyl caprate 50.0 parts The reversible color-changing color memory composition consisting of 8% polyvinyl alcohol was mixed with 40.0 parts of an aromatic polyvalent isocyanate prepolymer as a wall film material and 50.0 parts of a cosolvent as a wall film material. After emulsifying and dispersing in an aqueous solution to form microdroplets and continuing stirring while heating, 2.5 parts of a water-soluble aliphatic modified amine is added, and further stirring is continued to prepare a microcapsule pigment suspension. Obtained.
A microcapsule pigment was obtained by filtering the suspension with a filter press.
The volume average particle size of the microcapsule pigment was 1.73 μm, and the maximum particle size was 9.94 μm.
The microcapsule pigment has a complete decolorization temperature of 57 ° C. and a complete color development temperature of −20 ° C., and changes its color from magenta to colorless due to temperature change.

(Preparation of reversible thermochromic ink composition for inkjet)
10.0 parts of the microcapsule pigment (previously cooled and developed), 14.0 parts of morpholinoethyl (meth) acrylate, 10.0 parts of piperazinoethyl (meth) acrylate, 2-hydroxy-3- (4-) Benzoylphenoxy) -N, N, N-trimethyl-1-propaneammonium chloride 1.0 part, ethylene glycol 5.0 parts, antifungal agent (trade name: Proxel XL-2, manufactured by Zeneca Corporation) 0.2 parts , 0.5 parts of a defoaming agent (silicon type, trade name: SN deformer 381, manufactured by San Nopco Co., Ltd.) and 59.3 parts of water were uniformly mixed to prepare a reversible thermochromic ink composition.

(Ink container)
The ink composition was contained in an ink bottle having the same form as the ink container used in Example 1.

(inkjet printer)
The ink composition was stored in the inkjet printer used in Example 1.

Printing was performed on a recording paper (copy paper) using the above inkjet printer to form a reversible thermochromic image to obtain a reversible thermochromic printed matter.
In the above printing, scraping occurred.
During printing, the circulation mechanism was operated to flow the ink in the ink flow path and the printer head.
The reversible thermochromic image of magenta color is visually recognized at room temperature (25 ° C.) in the printed matter, and the reversible thermochromic image is erased by heating to 60 ° C. or higher, and the state immediately after printing (magenta) is obtained at −25 ° C. The state in which color printing was formed) was restored.

Comparative Example 4
(Preparation of reversible thermochromic microcapsule pigment)
As component (a), 9-ethyl- (3-methylbutyl) amino-spiro [12H-benzo [a] xanthene-12,1 '(3H) -isobenzofuran] -3'-one 6.0 parts, (b) A reversible color-changing color memory composition consisting of 15.0 parts of 4,4 '-(2-ethylhexylidene) bisphenol as a component and 50.0 parts of 4-benzyloxyphenylethyl caprate as a component (c) was uniformly applied. Was dissolved in the solution by heating, and a solution prepared by mixing 35.0 parts of an aromatic polyvalent isocyanate prepolymer as a wall film material and 50.0 parts of a cosolvent was emulsified and dispersed in an 8% aqueous polyvinyl alcohol solution to form fine droplets. After continuing stirring while heating, 2.5 parts of a water-soluble aliphatic modified amine was added, and stirring was further continued to obtain a microcapsule pigment suspension.
A microcapsule pigment was obtained by filtering the suspension with a filter press.
The volume average particle size of the microcapsule pigment was 5.26 μm, and the maximum particle size was 7.69 μm.
The microcapsule pigment has a complete decolorization temperature of 60 ° C. and a complete color development temperature of −25 ° C., and changes its color from magenta to colorless due to temperature change.
The 10% dispersion liquid of the microcapsule pigment had a zeta potential of 6.3 mV under the conditions of 20.0 ° C. and pH 5.2.

(Preparation of reversible thermochromic ink composition for inkjet)
10.0 parts of the microcapsule pigment (previously cooled and developed), 14.0 parts of morpholinoethyl (meth) acrylate, 10.0 parts of piperazinoethyl (meth) acrylate, 2-hydroxy-3- (4-) Benzoylphenoxy) -N, N, N-trimethyl-1-propaneammonium chloride 1.0 part, ethylene glycol 5.0 parts, antifungal agent (trade name: Proxel XL-2, manufactured by Zeneca Corporation) 0.2 parts , 0.5 parts of a defoaming agent (silicon type, trade name: SN deformer 381, manufactured by San Nopco Co., Ltd.) and 59.3 parts of water were uniformly mixed to prepare a reversible thermochromic ink composition.

Printing was performed on a recording paper (copy paper) using the above inkjet printer to form a reversible thermochromic image to obtain a reversible thermochromic printed matter.
Scratch was generated in the print.
During printing, the circulation mechanism was operated to flow the ink in the ink flow path and the printer head.
The reversible thermochromic image of magenta color is visually recognized at room temperature (25 ° C.) in the printed matter, and the reversible thermochromic image is erased by heating to 60 ° C. or higher, and the state immediately after printing (magenta) is obtained at −25 ° C. The state in which color printing was formed) was restored.

The formed printed image was evaluated as follows. The results obtained were as shown in Tables 1-3.
As described above, Comparative Example 1 was not evaluated because a print image was not formed.

(Evaluation of color development)
The color development of the print was visually observed.
◯: Dark and clear.
X: The color is light and there is a problem in practical use.

(Evaluation of fineness)
The fineness of printing was visually observed.
◯: There is no blur, and the start and end points of the character are clear.
X: There is blurring, or the start point and end point of the character are unclear.

t1 Full color development temperature of reversible thermochromic microcapsule pigment of heat bleaching type t2 Color development start temperature of reversible thermochromic microcapsule pigment of heat bleaching type t3 Decoloration of reversible thermochromic microcapsule pigment of heat bleaching type Starting temperature t4 Complete erasing temperature of heat-erasable reversible thermochromic microcapsule pigment ΔH Hysteresis width 1 Ink supply device 2 Ink container 3 Printer head 3a Ink discharge port 3b Ink intake 3c Internal flow path 4a Ink supply flow path 4b Ink collection flow path 5 Pump 6 Wiping means 7 Nozzle 8 Ink ejection port 9 Ink composition

Claims (6)

  An ink storage section, a printer head, an ink supply channel for supplying ink from the ink storage section to the printer head, and an ink recovery flow for returning ink not ejected from the nozzles of the printer head from the printer head to the ink supply channel. An ink composition housed in an ink jet printer that has a channel and circulates the ink through the ink supply channel, the printer head, and the ink recovery channel, and water and (a) electron donative coloration. Reversible thermochromic microcapsule pigment containing a reversible thermochromic composition composed of a water-soluble organic compound, (b) an electron-accepting compound, and (c) a reaction medium that determines the temperature at which the color reaction of both of them occurs. A microcapsule face in which the microphone capsule pigment has a volume average particle size of 0.1 to 5 μm and a particle size of more than 8 μm. A reversible thermochromic water-based ink composition for inkjet printers, which is characterized by containing no material particles.   An ink storage section, a printer head, an ink supply channel for supplying ink from the ink storage section to the printer head, and an ink recovery flow for returning ink not ejected from the nozzles of the printer head from the printer head to the ink supply channel. An ink composition housed in an ink jet printer that has a channel and circulates the ink through the ink supply channel, the printer head, and the ink recovery channel, and water and (a) electron donative coloration. Reversible thermochromic microcapsule pigment containing a reversible thermochromic composition comprising a water-soluble organic compound, (b) an electron-accepting compound, and (c) a reaction medium that determines the temperature at which the above-mentioned color reaction occurs. Agent and the microcapsule pigment has a positive or negative zeta potential in a liquid containing water and the microcapsule pigment. Has the dispersant, the zeta characterized by having a value opposite to a functional group which takes charge of the sign of the potential in the structure, for inkjet printers reversible thermal discoloration aqueous ink composition, wherein the microencapsulated pigment has.   An ink container containing the water-based ink composition according to claim 1 or 2.   An ink container set comprising a plurality of ink containers according to claim 3.   An ink container containing the water-based ink composition according to claim 1 or 2, a printer head, an ink supply channel for supplying ink from the ink container to the printer head, and a nozzle of the printer head. An ink jet printer comprising an ink recovery flow path for returning the ink that has not existed from the printer head to the ink supply flow path, and circulating ink through the ink supply flow path, the printer head, and the ink recovery flow path.   The inkjet printer according to claim 5, wherein the printer head includes a flow path for circulating ink in the printer head.

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