JP2008031314A - Thermal discoloring composition and thermal discoloring microcapsule - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal discoloring composition controlled to a desired discoloration temperature hysteresis. <P>SOLUTION: The thermal discoloring composition contains an electron-donative coloration organic compound, an electron-accepting compound and a desensitizing agent. The thermal discoloring composition contains at least two kinds of compound represented by general formulae (1): H(CH<SB>2</SB>)<SB>m</SB>-COO(CH<SB>2</SB>)<SB>n</SB>H and (2): H(CH<SB>2</SB>)<SB>n-1</SB>-COO(CH<SB>2</SB>)<SB>m+1</SB>H as the desensitizing agent. In the above (1) and (2), m represents an integer of 5 or more and n represents an integer of 5 or more. Provided that m and n except the values when the above (1) and (2) become the same compound. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a thermochromic composition and a thermochromic microcapsule. Furthermore, the present invention relates to a method for producing a thermochromic composition.

  The thermochromic composition reversibly develops and decolors depending on temperature, and is used for, for example, printed materials, inks, paints, packaging materials, recording materials and the like. As a typical example of such a composition, there is one using an electron transfer reaction between an electron donating color-forming organic compound (electron donor) and an electron accepting compound (electron acceptor) (Patent Document 1, Patent). Literature 2 etc.).

  In general, a thermochromic composition can reversibly repeat color development-decoloration or color erase-color development in a heating-cooling cycle, but usually a temperature difference between the color development temperature and the color erase temperature (so-called color change). Temperature hysteresis: ΔH) occurs. For example, as shown in FIG. 1, the case of ΔH = 0 ° C. is shown in FIG. 1B, and ΔH occurs in FIGS. 1A and 1C, respectively. FIG. 1A shows a case where the decoloring temperature becomes higher, and FIG. 1C shows a case where the coloring temperature becomes higher.

  On the other hand, as a technique for increasing the color change temperature hysteresis: ΔH, a specific fatty acid ester compound obtained from an aliphatic monohydric alcohol having an odd number of carbon atoms and an aliphatic carboxylic acid is used as a reaction medium, and the reaction medium A microcapsule pigment that exhibits a thermochromic property of a hysteresis width (line segment HG) of 8 ° C. to 30 ° C. by encapsulating a homogeneous solution composed of a color reaction component in a microcapsule is known (Patent Document 3). ). According to this microcapsule pigment, with respect to the color density-temperature curve, a hysteresis width (ΔH) of 8 ° C. to 30 ° C. is exhibited to cause reversible discoloration of color development / decoloration. Both of the colors on the side can be stored in a reciprocal manner in the normal temperature range, and by applying heat or cold as necessary, any color can be reversibly reproduced and stored and retained effectively. It can be made to be.

  Further, for example, (a) an electron-donating color-forming organic compound, (b) an electron-accepting compound, (c) a reaction medium that determines the temperature at which the color reaction of (a) and (b) occurs, and (d) ) When a color change temperature adjusting agent is included as the essential four components, and (d) the color change temperature adjusting agent has a melting point of Y ° C., (X) 16) ≦ Y ≦ ( X + 100) selected from ethers, esters, ketones, acid amides, and fatty acids that satisfy the relationship of + 100 ° C., and the essential four components are encapsulated in microcapsules. The temperature-color density curve shows a hysteresis width (ΔH) of 5 ° C. to 80 ° C. and discolors, and the colors exhibited in each temperature range below the low temperature side trigger and above the high temperature side trigger are the low temperature side trigger and the high temperature side trigger. In a temperature range between Thermochromic coloring color-memory microcapsule pigment to 憶 held has been proposed (Patent Document 4).

And (b) an electron-donating color-forming organic compound, (b) an electron-accepting compound, (c) a reaction medium for determining the temperature at which the color reaction of (a) and (b) occurs, and (d) When the color change temperature adjusting agent is contained as essential four components and the (d) color change temperature adjusting agent has a melting point of Y ° C., the relationship of X + 30 ≦ Y ≦ 200 with respect to the melting point (X ° C.) of the component (c). A reversible thermochromic microcapsule comprising one or more compounds selected from esters, alcohols, ketones, acid amides, hydrocarbons, and fatty acids to be filled, wherein the essential four components are encapsulated in the microcapsule. A pigment has also been proposed (Patent Document 5).
JP-A-6-65568 Japanese Patent Publication No. 4-17154 JP 7-33997 A JP 2001-152041 A JP 2002-12787 A

  However, these conventional techniques have a problem that it is difficult to finely adjust the color change temperature hysteresis. For example, in the microcapsule pigment disclosed in Patent Document 3 or the like, it is difficult or impossible to adjust the color change temperature hysteresis continuously or stepwise. Therefore, it is extremely difficult to produce thermochromic compositions having the desired color change temperature hysteresis with these techniques.

  Accordingly, a main object of the present invention is to provide a thermochromic composition controlled to a desired color change temperature hysteresis.

  As a result of intensive studies to solve the problems of the prior art, the present inventor has found that the above object can be achieved by adopting a combination of specific components as an ink composition, thereby completing the present invention. It came.

That is, the present invention relates to the following thermochromic composition and thermochromic microcapsule.
1. A thermochromic composition comprising an electron-donating color-forming organic compound, an electron-accepting compound and a desensitizer,
As the desensitizer, at least two compounds represented by the following general formulas (1) and (2);

(In the above (1) and (2), m represents an integer of 5 or more, and n represents an integer of 5 or more, provided that m and n are the same compounds in (1) and (2). Excluding the case value.)
A thermochromic composition comprising:
2. Item 2. The thermochromic composition according to Item 1, wherein the weight ratio of the compound (1) to the compound (2) is 1: 0.4 to 2.5.
3. Item 3. The thermochromic composition according to Item 1 or 2, wherein the total content of the compound (1) and the compound (2) is 60 to 90% by weight in the thermochromic composition.
4). Item 4. The thermochromic composition according to any one of Items 1 to 3, wherein the discoloration temperature hysteresis is less than 5 ° C.
5. Item 5. The thermochromic composition according to any one of Items 1 to 4, wherein a difference in melting point between the compound (1) and the compound (2) is less than 30 ° C.
6). The thermochromic composition according to any one of Items 1 to 5, which includes (1) a combination of stearyl laurate and lauryl stearate or (2) a combination of stearyl palmitate and palmitic acid stearate as the two kinds of compounds. object.
7). A thermochromic microcapsule comprising the composition according to any one of Items 1 to 6 encapsulated in a microcapsule.
8). A method for producing a thermochromic composition comprising an electron-donating color-forming organic compound, an electron-accepting compound and a desensitizer,
As the desensitizer, at least two compounds represented by the following general formulas (1) and (2);

(In the above (1) and (2), m represents an integer of 5 or more, and n represents an integer of 5 or more, provided that m and n are the same compounds in (1) and (2). Excluding the case value.)
A method for producing a thermochromic composition having a desired color change temperature hysteresis by changing the hysteresis ratio by changing the mixing ratio of the two.
9. Item 9. The method according to Item 8, wherein the weight ratio of the compound (1) to the compound (2) is 1: 0.4 to 2.5.
10. Item 10. The production method according to Item 8 or 9, wherein the total content of the compound (1) and the compound (2) is 50 to 90% by weight in the thermochromic composition.
11. Item 11. The method according to any one of Items 8 to 10, wherein the discoloration temperature hysteresis is less than 5 ° C.
12 Item 12. The production method according to any one of Items 8 to 11, wherein the difference in melting point between the compound (1) and the compound (2) is less than 30 ° C.
13. Item 13. The production method according to any one of Items 8 to 12, which comprises (1) a combination of stearyl laurate and lauryl stearate or (2) a combination of stearyl palmitate and palmitic acid stearate as the two kinds of compounds.

  According to the method for producing a thermochromic composition of the present invention, since a combination of desensitizers (ester compounds) having a specific relationship between the chemical structures of each other is employed, the color change temperature corresponding to the blending ratio thereof. The hysteresis ΔH can be set freely. That is, ΔH is arbitrarily set continuously or stepwise within a range from 0 ° C. to a desired value (preferably 20 ° C. or less, more preferably less than 5 ° C., most preferably 4.5 ° C. or less). Is possible. In particular, as shown in the examples described later, in the present invention, the amount of the desensitizer added and the color change temperature hysteresis ΔH can be given a linear relationship, so that the color change temperature hysteresis ΔH can be more systematically and precisely set. Design can be done.

  As described above, since ΔH is controlled continuously or stepwise as described above, the thermochromic composition of the present invention can provide an optimal thermochromic composition in various applications. Further, in the thermochromic composition of the present invention, since the ester compound acts as a desensitizer, the desired color developability and color development and decoloring of the thermochromic composition are not hindered. Decolorization can be ensured.

  The thermochromic composition of the present invention can be used for various applications. For example, it is suitably used for imparting thermal discoloration to various materials and products such as ink, printed matter, plastic molding, packaging material, recording material, and fiber.

1. Thermochromic composition The thermochromic composition of the present invention is a thermochromic composition comprising an electron donating color-forming organic compound, an electron accepting compound and a desensitizer,
As the desensitizer, at least two compounds represented by the following general formulas (1) and (2);

(In the above (1) and (2), m represents an integer of 5 or more, and n represents an integer of 5 or more, provided that m and n are the same compounds in (1) and (2). Excluding the case value.)
It is characterized by including.

Electron-donating color- forming organic compound The electron-donating color-forming organic compound (color-developing agent) is not limited as long as it reacts with the electron-accepting compound (developer) and develops color. Can be used. For example, the following compounds can be preferably used. These can be used alone or in combination of two or more.

(A) Fluoranes 2 '-[(2-chlorophenyl) amino] -6'-(dibutylamino) -spiro [isobenzofuran-1 (3H), 9 '-(9H) xanthen] -3-one, 3 -Diethylamino-6-methyl-7-chlorofluorane, 3-dimethylaminobenzo (a) -fluorane, 3-amino-5-methylfluorane, 2-methyl-3-amino-6,7-dimethylfluorane, 2-Bromo-6-cyclohexylaminofluorane, 6 '-(ethyl (4-methylphenyl) amino-2'-(N-methylphenylamino) -spiro (isobenzofuran 1 (3H), 9 '-(9H) Xanthene) -3-one and the like;
(B) Fluorenes ... 3,6-bis (diethylamino) fluorene spiro (9.3 ')-4'-azaphthalide, 3,6-bis (diethylamino) fluorene spiro (9.3')-4 ', 7' -Diazaphthalide etc .;
(C) Diphenylmethanephthalides: 3,3-bis- (p-ethoxy-4-dimethylaminophenyl) phthalide and the like;
(D) Diphenylmethane azaphthalides ... 3,3-bis- (1-ethoxy-4-diethylaminophenyl) -4-azaphthalide and the like;
(F) Indolylphthalides: 3,3-bis (n-butyl-2-methylindol-3-yl) phthalide, 3,3-bis (1-ethyl-2-methylindol-3-yl) phthalide etc;
(G) Phenylindolylphthalides: 3- (1-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) phthalide and the like;
(H) Phenylindolylazaphthalides: 3- (2-Ethoxy-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 and the like;
(I) styrylquinolines: 2- (3-methoxy-4-dodecoxystyryl) quinoline and the like;
(J) Pyridines: 2,6-diphenyl-4- (6-dimethylaminophenyl) pyridine, 2,6-diethoxy-4- (4-diethylaminophenyl) pyridine and the like;
(K) quinazolines: 2- (4-N-methylanilinophenyl) -1-phenoxyquinazoline, 2- (4-dimethylaminophenyl) -4- (1-methoxyphenyloxy) quinazoline and the like;
(L) Biskinazolines: 4,4 ′-(ethylenedioxy) -bis [2- (1-diethylaminophenyl) quinazoline], 4,4 ′-(ethylenedioxy) -bis [2- (1-di -N-butylaminophenyl) quinazoline] and the like;
(M) Ethylenophthalides: 3,3-bis [1,1-bis- (p-dimethylaminophenyl) ethyleno-3] phthalide and the like;
(N) Ethylene azaphthalides ... 3,3-bis [1,1-bis- (p-dimethylaminophenyl) ethyleno-2] -4-azaphthalide, 3,3-bis [1,1-bis- (P-dimethylaminophenyl) ethyleno-2] -4,7-diazaphthalide and the like;
(O) Triphenylmethanephthalides: Crystal violet lactone, malachite green lactone, etc .;
(P) Polyaryl carbinols: Michler hydrol, crystal violet carbinol, malachite green carbinol, etc .;
(Q) leucooramines: N- (2,3-dichlorophenynyl) leucooramine, N-benzoylolamine, N-acetyloramine and the like;
(R) Rhodamine lactams: Rhodamine β-lactam, etc .;
(S) Indolines: 2- (phenyliminoethylidene) -3,3-dimethylindoline and the like;
(T) Spiropyrans: N-3,3-trimethylindolinobenzospiropyran, 8-methoxy-N-3,3-trimethylindolinobenzospiropyran, etc .;
In addition to these, diazarhodamine lactones, xanthenes and the like can also be used in the present invention.

  In the present invention, at least one of fluorans among these electron donating color-forming organic compounds can be suitably used. In particular, 2 '-[(2-chlorophenyl) amino] -6'-(dibutylamino) -spiro [isobenzofuran-1 (3H), 9 '-(9H) xanthen] -3-one is more preferable.

  The content of the electron-donating color-forming organic compound can be appropriately set according to the type of the compound, but generally it is about 0.1 to 50% by weight, particularly 0 in the thermochromic composition of the present invention. It is desirable to be 8 to 15% by weight. When the content is less than 0.1% by weight, the color density may be lowered. Moreover, when the said content exceeds 50 weight%, there exists a possibility that background coloring may become large.

Electron-accepting compound The electron-accepting compound is not limited, and known or commercially available compounds can be used as appropriate. For example, the following compounds can be preferably used. These can be used alone or in combination of two or more.

(A) Phenols: Bisphenol A or derivatives thereof, bisphenol S or derivatives thereof, p-phenylphenol, dodecylphenol, o-bromophenol, ethyl p-oxybenzoate, methyl gallate, phenol resin, etc. (b) Phenols Metal salts of phenols: Metal salts of phenols such as Na, K, Li, Ca, Zn, Al, Mg, Ni, Co, Sn, Cu, Fe, Ti, Pb, Mo, etc. (c) Aromatic carboxylic acids and carbon Aliphatic carboxylic acids of formula 2-5: phthalic acid, benzoic acid, acetic acid, propionic acid, etc. (d) Metal salts of carboxylic acids ... Sodium oleate, zinc salicylate, nickel benzoate, etc. (e) Acidic phosphate esters ... Butyl acid phosphate, 2-ethylhexyl-acid phosphate, dodecyl acid phosphate (F) Metal salts of acidic phosphate esters: Metal salts of acidic phosphate esters such as Na, K, Li, Ca, Zn, Al, Mg, Ni, Co, Sn, Fe, Ti, Pb, and Mo (G) Triazole compound: 1,2,3-triazole, 1,2,3-benzotriazole, etc. (h) Thiourea and its derivatives ... diphenylthiourea, di-o-toluylurea, etc. (i) Halohydrins ... 2 , 2,2-trichloroethanol, 1,1,1-tribromo-2-methyl-2-propanol, N-3-pyridyl-N ′-(1-hydroxy-2,2,2-trichloroethyl) urea, etc. j) Benzothiazoles… 2-mercaptobenzenethiazole, 2- (4′-morpholinodithio) benzothiazole, N-tert-butyl-2-benzothiazolylsulfenamide, 2-mer The Zn salts present invention script benzothiazole, it may be used at least one suitably phenols and their metal salts of these electron-accepting compound. In particular, at least one selected from 1) bisphenol A and derivatives thereof and 2) bisphenol S and derivatives thereof is more preferable, and 2,2-bis (4′-hydroxyphenyl) propane is most preferable.

  The content of the electron-accepting compound can be appropriately set according to the type of the compound, but generally it is about 0.05 to 98% by weight, particularly 0.5 to 77% in the thermochromic composition of the present invention. It is desirable to set the weight%. When the content is less than 0.05% by weight, the color density may be lowered. Moreover, when the said content exceeds 98 weight%, there exists a possibility that background coloring may become large.

  In the present invention, in relation to the electron donating colorable organic compound, 0.1 to 100 parts by weight, particularly 0.5 to 100 parts by weight of the electron accepting compound with respect to 1 part by weight of the electron donating colorable organic compound. 20 parts by weight is preferable.

As the desensitizer desensitizer , at least two compounds represented by the following general formulas (1) and (2);

(In the above (1) and (2), m represents an integer of 5 or more, and n represents an integer of 5 or more, provided that m and n are the same compounds in (1) and (2). Excluding the case value.)
including.

  Said m shows an integer greater than or equal to 5, Preferably it is an integer of 9-21, More preferably, it is an integer of 11-17. Said n shows an integer greater than or equal to 5, Preferably it is an integer of 10-22, More preferably, it is an integer of 12-18.

The m and n exclude combinations when the compounds (1) and (2) are the same. For example, when m = 5 and n = 6, the compounds (1) and (2) are both C ₅ H ₁₁ COOC ₆ H ₁₃ (hexyl caproate), and the combination of m and n in this case is Excluded.

  The two types of compounds preferably include (A) a combination of stearyl laurate and lauryl stearate or (B) a combination of stearyl palmitate and palmityl stearate. By using these combinations, it is possible to control ΔH with higher accuracy. For example, when a combination of these (A) or (B) (two-component system as a desensitizer) is employed, ΔH can be brought close to 0 ° C., preferably 0 ° C. ≦ ΔH ≦ 1 ° C. . Further, ΔH can be continuously increased by continuously changing the ratio of the compounds (1) and (2).

  In the present invention, it is desirable to employ a two-component system comprising the compounds (1) and (2) as a desensitizer. However, other desensitizers can be used in combination as long as the control of ΔH is not significantly hindered. For example, the following desensitizer can also be used.

(A) Alcohols: n-cetyl alcohol, n-octyl alcohol, cyclohexyl alcohol, hexylene glycol, etc. (b) Esters: myristic acid ester, lauric acid ester, dioctyl phthalate, etc. (c) Ketones: methyl hexyl ketone (D) Ethers: butyl ether, diphenyl ether, distearyl ether, etc. (e) Acid amide compounds: oleic acid amide, stearic acid amide, lauric acid amide, lauric acid N-octylamide, caproic acid anilide, etc. (F) Fatty acids having 6 or more carbon atoms: lauric acid, stearic acid, 2-oxymyristic acid, etc. (g) Aromatic compounds: diphenylmethane, dibenzyltoluene, propyldiphenyl, isopropylnaphthalene, 1,1,3-tri (H) Thiols ... n-decyl mercaptan, n-myristyl mercaptan, n-stearyl mercaptan, isocetyl mercaptan, dodecyl benzine mercaptan, etc. (i) Sulfides ... di-n- Octyl sulfide, di-n-decyl sulfide, diphenyl sulfide, diethylphenyl sulfide, etc. (j) Disulfides ... Di-n-octyl disulfide, di-n-decyl disulfide, diphenyl disulfide, dinaphthyl disulfide, etc. (k) Sulfoxides ... Diethyl sulfoxide, tetramethylene carboxyoxide, diphenyl sulfoxide, etc. (l) Sulfones ... Diethyl sulfone, dibutyl sulfone, diphenyl sulfone, dibenzyl sulfone, etc. (m) Azomethines ... Nylidene lauryl amine, p-methoxybenzylidene lauryl amine, benzylidene p-anisidine, etc. (n) Fatty acid primary amine salts: stearylamine oleate, myristylamine stearate, stearylamine behenate, etc. Content of desensitizer (total amount) Can be appropriately set according to the type of the compound, etc., but generally about 1 to 99% by weight, particularly 19 to 99% by weight, more preferably 60 to 90% by weight in the thermochromic composition of the present invention. It is desirable to do. If the content is less than 1% by weight, the background color may increase. On the other hand, when the content exceeds 99% by weight, the color density may be lowered.

  In the present invention, the content ratio of the two kinds of desensitizers is not limited, but generally (compound of (1)) :( compound of (2)) = 1: 0.4-2 It is desirable to set within the range of 0.5 (weight ratio). Within this range, ΔH can be made closer to 0 ° C.

  In the present invention, the two desensitizers have a difference in melting point of less than 30 ° C., particularly 20 ° C. or less. By using two kinds of desensitizers in such a combination, ΔH can be more suitably controlled.

Other components In the thermochromic composition of the present invention, if necessary, an ultraviolet absorber, an infrared absorber, an antioxidant, a non-thermochromic pigment, a non-thermochromic dye, a fluorescent whitening agent, a surfactant. Further, known additives such as an antifoaming agent, a leveling agent, a solvent, and a thickener may be added to the composition.

(2) Manufacturing method of thermochromic composition The thermochromic composition of the present invention can be prepared by putting these components into a known mixer such as a stirrer, mixer, homogenizer and the like and mixing them uniformly. it can. In this case, it is preferable to mix while heating. The heating temperature is not limited, but is usually about 120 to 180 ° C.

In particular, the present invention is a method for producing a thermochromic composition comprising an electron donating color-forming organic compound, an electron accepting compound and a desensitizer,
As the desensitizer, at least two compounds represented by the following general formulas (1) and (2);

(In the above (1) and (2), m represents an integer of 5 or more, and n represents an integer of 5 or more, provided that m and n are the same compounds in (1) and (2). Excluding the case value.)
In the production of a thermochromic composition having a desired color change temperature hysteresis by changing the color change temperature hysteresis ΔH by changing the mixing ratio of the two.

  That is, by changing the blending ratio of (1) and (2), ΔH can be set according to the blending ratio. Specifically, if the total amount of (1) and (2) is 100 parts by weight, 0 part by weight <[the ratio of (1) or the ratio of (2)] <100 parts by weight. The desired ΔH can be obtained by continuously changing at. In particular, as described above, it is desirable to set within the range of (compound (1)) :( compound (2)) = 1: 0.4 to 2.5 (weight ratio). Within this range, ΔH can be made closer to 0 ° C.

  Further, as described above, in the present invention, the difference between the melting points of the two kinds of desensitizers is preferably less than 30 ° C, particularly preferably 20 ° C or less. By using two kinds of desensitizers in such a combination of melting points, ΔH can be controlled more suitably.

The present invention relates to a method for controlling a color change temperature hysteresis ΔH in a thermochromic composition comprising an electron donating color-forming organic compound, an electron accepting compound and a desensitizer,
As the desensitizer, at least two compounds represented by the following general formulas (1) and (2);

(In the above (1) and (2), m represents an integer of 5 or more, and n represents an integer of 5 or more, provided that m and n are the same compounds in (1) and (2). Excluding the case value.)
In blending, the method of changing the color change temperature hysteresis ΔH by changing the blending ratio of both compounds is included. The condition of this method may be the same as that of the above manufacturing method.

(3) Thermochromic microcapsules The present invention includes thermochromic microcapsules obtained by encapsulating the thermochromic composition in microcapsules. Except for using the thermochromic composition of the present invention as the contents, a structure similar to that of known microcapsules can be employed. For example, the microcapsule which encloses the content containing a thermochromic composition with a wall film is mentioned.

  In addition to the thermochromic composition, the contents may include a solvent (dissolution aid), an emulsifier, and the like as necessary.

  The content of the thermochromic composition is not limited, but generally it is preferably about 6 to 98% by weight, particularly 75 to 95% by weight when the microcapsule is 100% by weight.

  The solvent can be appropriately selected from known solvents as long as the thermochromic composition and the wall film material can be uniformly dissolved and the thermochromic performance is not impaired. In particular, those that can be removed in a later step are desirable. For example, ester solvents (excluding the compounds of (1) and (2) above), ketone solvents, ether solvents, glycol ether solvents, hydrocarbon solvents, aromatic solvents, nitrogen-containing solvents, Silicon solvents, halogen-containing solvents, etc. can be used. These can be used alone or in combination of two or more.

  As the emulsifier, an amphiphilic substance that is adsorbed on the surface of the oil droplet and stabilized when the content is emulsified in water can be suitably used. These can be employed from known emulsifiers. For example, water-soluble natural polymers, water-soluble synthetic polymers, surfactants, inorganic fine particles and the like can be mentioned. These can be used alone or in combination of two or more. The emulsifier can be appropriately determined according to the type of the resin component constituting the wall film. For example, when the resin component is an epoxy resin, casein or the like can be suitably used as the emulsifier, in addition to polysaccharides such as gum arabic and gelatin. For example, when a melamine formalin resin is used as a resin component, an ethylene maleic anhydride copolymer or the like can be suitably used as an emulsifier. Furthermore, when urethane (isocyanate) is used as the resin component, gelatin, polyvinyl alcohol, or the like can be used.

  In general, a resin-based wall film can be suitably used as the wall film. As the resin, for example, various thermoplastic resins and thermosetting resins can be used. More specifically, epoxy resin, polyamide resin, acrylonitrile resin, polyurethane resin, polyurea resin, urea-formaldehyde resin, melamine-formaldehyde resin, benzoguanamine resin, butylated melamine resin, butylated urea resin, urea-melamine system Examples thereof include resins. These resin components can be used alone or in combination of two or more. When manufacturing microcapsules, these raw materials are used, and these can be polymerized suitably by polymerizing them.

(4) Method for producing thermochromic microcapsules The method for producing the thermochromic microcapsules of the present invention is carried out according to known microencapsulation except that the thermochromic composition of the present invention is used as the contents. Can do. Examples of the microencapsulation method include an interfacial polymerization method (polycondensation and addition polymerization), an in situ polymerization method, a coacervation method, a submerged drying method, and a spray drying method.

  Specifically, as an example of the method for producing the microcapsules of the present invention, for example, 1) In the presence or absence of a solvent, the main raw material (excluding the crosslinking agent) that can constitute the wall film is thermochromic. A first step of preparing a solution by mixing or dissolving with the composition, 2) a second step of adding the obtained solution to an aqueous emulsifier solution to prepare an O / W emulsion, and 3) a crosslinking agent or a solution thereof. A microcapsule can be suitably produced by a method including the third step of adding to the O / W emulsion. Hereinafter, each step will be described.

First Step In the first step, in the presence or absence of a solvent, a solution is prepared by mixing or dissolving a main raw material (excluding a crosslinking agent) that can constitute a wall film with a thermochromic composition. .

  As the thermochromic composition, those described above are used. The amount of the thermochromic composition used is usually preferably 5 to 50 parts by weight, particularly 10 to 40 parts by weight, based on 100 parts by weight of the emulsifier aqueous solution. When the amount used is less than 5 parts by weight, productivity may be reduced. Moreover, when the said usage-amount exceeds 50 weight part, there exists a possibility that emulsification may become difficult.

  What is necessary is just to use what becomes a component which comprises the wall film demonstrated by said (3) as said main raw material and a crosslinking agent. In this case, it is more desirable to set appropriately according to the microencapsulation method. For example, in the case of microencapsulation by an in situ polymerization method, when the wall film is made of melamine resin, polyurea resin or the like, melamine, urea or the like may be used as the main raw material and formalin may be used as the crosslinking agent. In the case of microencapsulation by an in situ polymerization method, when the wall film is a urethane resin or the like, an isocyanate compound may be used as a main raw material and a polyalcohol may be used as a crosslinking agent. For example, in the case of microencapsulation by the interfacial polymerization method (polycondensation), when the wall film is an epoxy resin or the like, an epoxy compound may be used as a main raw material and a polyamine compound may be used as a crosslinking agent. In the case of microencapsulation by the interfacial polymerization method (polycondensation), when the wall film is a urethane resin, urea urethane resin, etc., an isocyanate compound is used as a main raw material, and a polyamine compound, polyalcohol, water, etc. are used as a crosslinking agent. Use it. In the case of microencapsulation by the interfacial polymerization method (polycondensation), when the wall film is a polyamide resin or the like, an acid chloride compound may be used as a main raw material and a polyamine compound may be used as a crosslinking agent. In the case of microencapsulation by the interfacial polymerization method (addition polymerization), when the wall film is an acrylic resin or the like, an acrylic compound may be used as a main raw material and a peroxy compound may be used as a crosslinking agent.

  The amount of the main raw material and the crosslinking agent used is not particularly limited. The main raw material can be appropriately set in the range of usually 1 to 50 parts by weight, preferably 2 to 10 parts by weight with respect to 100 parts by weight of the emulsifier aqueous solution. The crosslinking agent can be appropriately set within the range of usually 0.5 to 25 parts by weight, preferably 1 to 5 parts by weight with respect to 100 parts by weight of the emulsifier aqueous solution. When the amount of the main raw material or the crosslinking agent used is too small or too large, the reaction becomes insufficient, and the strength, heat resistance, etc. of the capsule (wall film) may be lowered.

  In the first step, a solvent can be used as necessary. As the solvent, those listed above can be used.

  Although the usage-amount of a solvent is not limited, Usually, it can set suitably in the range of 0-100 weight part with respect to 100 weight part of emulsifier aqueous solution, Preferably it is in the range of 0-400 weight part.

Second Step In the second step, the obtained solution is added to an aqueous emulsifier solution to prepare an O / W emulsion.

  As the emulsifier aqueous solution, an aqueous solution obtained by dissolving the above emulsifier in water can be used. The concentration of the aqueous emulsifier solution can be appropriately set according to the type of the emulsifier and the like, but is generally 0.1 to 15% by weight, particularly preferably 0.5 to 8% by weight. If the concentration is less than 0.2% by weight, emulsification may be difficult. If the concentration exceeds 15% by weight, foaming may occur.

  In the present invention, the O / W emulsion can be prepared according to a known method such as a stirring method or a membrane permeation method. In this case, the droplet diameter of the O / W emulsion may be appropriately set within a range of about 0.1 to 20 μm.

Third Step In the third step, a crosslinking agent or a solution thereof is added to the O / W emulsion. As a crosslinking agent, each crosslinking agent enumerated above can be used. As the solution of the crosslinking agent, for example, an aqueous crosslinking agent solution obtained by dissolving the crosslinking agent in water can be suitably used. The concentration of the aqueous solution in this case is not limited, but usually it may be appropriately set within a range of about 1 to 100% by weight. The method for adding the cross-linking agent is not particularly limited, but it is preferable to add it by dropping.

  As a special example, when an isocyanate compound is used as a wall film raw material, an amine compound generated by the reaction of water and an isocyanate in an aqueous emulsifier solution can be used as a crosslinking agent without newly adding a crosslinking agent. .

  After the addition of the cross-linking agent or the solution thereof, the cross-linking proceeds and if the cross-linking is completed, the desired microcapsules can be obtained in the form of a slurry. Thereafter, if necessary, the microcapsules can be recovered as a solid content according to a known solid-liquid separation method such as filtration or centrifugation. In addition, the microcapsules can be washed as necessary.

  Examples and comparative examples are shown below to further clarify the features of the present invention. In addition, this invention is not limited to an Example.

Examples 1-10 and Comparative Examples 1-2
Each thermochromic composition was prepared by uniformly mixing each component shown in Table 1 with a stirrer while heating at 120 to 180 ° C.

Examples 11-20 and Comparative Examples 3-4
The thermochromic compositions obtained in Examples 1-10 and Comparative Examples 1-2 were microencapsulated using the materials shown in Table 2. First, the resin main ingredient (main raw material) used as the capsule wall film and the thermochromic composition were uniformly mixed and dissolved using a dissolution aid (solvent) to obtain a solution. Subsequently, the said solution was added in the emulsifier aqueous solution heated at 30-60 degreeC, carrying out medium shear stirring. Next, O / W emulsion (droplet particle size: about 5 μm) was obtained from the solution by performing high shear stirring. Thereafter, the stirring was switched to low shear stirring, and the aqueous crosslinking agent solution was dropped into the O / W emulsion. After reacting at a temperature of 60 to 90 ° C. for 3 to 12 hours, the slurry was cooled to room temperature to obtain a slurry in which microcapsules were dispersed.

Test example 1
The thermochromic compositions obtained in Examples and Comparative Examples and microcapsules were examined for thermochromic properties.

<Preparation of sample>
In Examples 1-10 and Comparative Examples 1-2, the thermochromic composition heated to 70-100 degreeC was No .. A sample for colorimetry was prepared by dropping 0.05 g on 5 filter papers and impregnating by heating at 120 ° C. for 10 minutes.

  In Examples 11 to 20 and Comparative Examples 3 to 4, the microcapsule slurry cooled to room temperature was screen-printed on Kent paper and dried at room temperature for 2 hours to obtain a sample for colorimetry.

<Evaluation>
A color difference meter (product name “CR-300” manufactured by Minolta) was used for the color measurement of the sample, and the color density was indicated by the color difference ΔE * from the white calibration plate.

  As a measurement procedure, the color measurement was repeated by heating in steps of 1 ° C. from −10 ° C. to a temperature at which the sample was completely decolored. As indicated by the solid line in FIG. 2, the color difference ΔE * plotted against the temperature (horizontal axis) was defined as the decoloring curve.

  The sample was cooled in steps of 1 ° C. from the temperature at which the sample completely disappeared to −10 ° C., and the color measurement was repeated. As indicated by the dotted line in FIG. 2, the color difference ΔE * plotted against the temperature (horizontal axis) was defined as a color development curve.

In the decoloring curve and the coloring curve, as shown in FIG. 3, the discoloration width between the maximum value (ΔE * _max ) and the minimum value (ΔE * _min ) of the color difference ΔE * of each curve is ΔE. The temperature corresponding to [ΔE * _min + (ΔE / 2)] was defined as the discoloration temperature (decoloration temperature t1, color development temperature t2). FIG. 3 is a diagram for explaining the case of a decoloring curve, but the coloring curve also conforms to this.

  Next, the discoloration temperature hysteresis ΔH = | t2−t1 | (absolute value) was calculated from t1 and t2 obtained above. The results are shown in Table 1 and Table 2, respectively. Furthermore, the results of Table 1 and Table 2 are shown in FIGS. 4 and 5, respectively.

  From the results of Tables 1 and 2 and FIGS. 4 and 5, it can be seen that the color change temperature hysteresis ΔH can be controlled continuously or stepwise according to the proportion of the desensitizer. In particular, as is apparent from FIGS. 4 and 5, since the relationship between ΔH and the content of the desensitizer is almost linear, ΔH is relatively finely adjusted according to the content of the desensitizer. It can also be adjusted.

It is a figure for demonstrating the presence or absence of a discoloration temperature hysteresis in a thermochromic composition. It is a figure which shows the decoloring curve and coloring curve used in a test example. In a test example, it is a decoloring curve for demonstrating decoloring temperature t1 (and coloring temperature t2). It is a graph which shows the relationship between (DELTA) H of Table 1, and content of a desensitizer. It is a graph which shows the relationship between (DELTA) H of Table 2, and content of a desensitizer.

Claims (13)

A thermochromic composition comprising an electron-donating color-forming organic compound, an electron-accepting compound and a desensitizer,
As the desensitizer, at least two compounds represented by the following general formulas (1) and (2);

(In the above (1) and (2), m represents an integer of 5 or more, and n represents an integer of 5 or more, provided that m and n are the same compounds in (1) and (2). Excluding the case value.)
A thermochromic composition comprising: The thermochromic composition according to claim 1, wherein the weight ratio of the compound (1) to the compound (2) is 1: 0.4 to 2.5. The thermochromic composition according to claim 1 or 2, wherein the total content of the compound (1) and the compound (2) is 60 to 90% by weight in the thermochromic composition. The thermochromic composition according to any one of claims 1 to 3, wherein the discoloration temperature hysteresis is less than 5 ° C. The thermochromic composition according to any one of claims 1 to 4, wherein a difference in melting point between the compound (1) and the compound (2) is less than 30 ° C. The thermochromic composition according to any one of claims 1 to 5, comprising (1) a combination of stearyl laurate and lauryl stearate or (2) a combination of stearyl palmitate and palmitic acid stearate as the two kinds of compounds. object. A thermochromic microcapsule obtained by encapsulating the composition according to claim 1 in a microcapsule. A method for producing a thermochromic composition comprising an electron-donating color-forming organic compound, an electron-accepting compound and a desensitizer,
As the desensitizer, at least two compounds represented by the following general formulas (1) and (2);

(In the above (1) and (2), m represents an integer of 5 or more, and n represents an integer of 5 or more, provided that m and n are the same compounds in (1) and (2). Excluding the case value.)
A method for producing a thermochromic composition having a desired color change temperature hysteresis by changing the hysteresis ratio by changing the mixing ratio of the two. The production method according to claim 8, wherein the weight ratio of the compound (1) to the compound (2) is 1: 0.4 to 2.5. The production method according to claim 8 or 9, wherein the total content of the compound (1) and the compound (2) is 50 to 90% by weight in the thermochromic composition. The manufacturing method in any one of Claims 8-10 whose discoloration temperature hysteresis is less than 5 degreeC. The manufacturing method in any one of Claims 8-11 whose difference of melting | fusing point of the compound of said (1) and the said compound of (2) is less than 30 degreeC. The production method according to any one of claims 8 to 12, comprising (1) a combination of stearyl laurate and lauryl stearate or (2) a combination of stearyl palmitate and palmitic acid stearate as the two kinds of compounds.

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