JP2005262577A - Coating composition and thermal development recording method for coating - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating composition which is almost colorless before processing but can develop color or make record in an optional hue by forming and drying a coating film and then applying thermal energy from outside, and a thermal development recording method using this coating. <P>SOLUTION: This coating composition contains at least a substantially colorless developing component (a) and a developing component (b) which come into contact with and chemically react each other by applying the thermal energy from outside, either of these components (a) and (b) being encapsulated in a microcapsule. Thus the coating composition contains at least not less than two kinds of the microcapsules with differing thermal sensitivity. The microcapsule is preferably a microcapsule consisting of at least not less than two kinds of wall materials with differing glass transition temperature. Especially the wall material of the microcapsule is preferably composed of a polyurethane polymer and/or a polyurea polymer. Also the thermal development recording method using the coating composition is provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a coating composition, and more specifically, a coating composition capable of coloring or recording in an arbitrary hue by applying thermal energy to a substantially colorless coating film after drying, and thermal coloring recording of the coating Regarding the method.

  In modern society, a large amount of labels, stickers, stickers, patches, etc. are used to identify information and classify articles and materials over a wide range of industrial, commercial, office, home, etc. Is used. Among them, a multicolored label or the like is frequently used because it can be quickly and reliably identified and classified.

For example, color labels to identify and classify articles and materials in mass-market stores such as supermarkets and convenience stores, conveyor-type production lines that assemble a large number of parts, and automatic transport warehouses that stock a wide variety of products. And multicolored signs printed with letters or images are commonly used.
On the other hand, in automobiles, buildings, and interior equipment, etc., there is a demand for diversification of appearance and design, and sophistication of exterior quality. For example, in automobiles and furniture, there are a great variety of colors or novelty. A painted product having a design is provided.

Conventionally, for such multi-color (color) labels such as labels, stickers, stickers, and emblems, various types of media printed with individual information are prepared, or the required color printing media are prepared. There was a need to do. Therefore, there have been problems such as an increase in costs associated with an increase in these manufacturing processes and inventory management.
For example, if the coating composition is a colorless or light-colored coating film before processing but can develop or record a desired arbitrary hue on the coating film after drying, it is useful because it can practically meet the above needs. However, so far no such coating composition has been provided.

In applications such as automobiles and furniture home appliances, for example, the following Patent Documents 1 to 6 are disclosed as dichroic or polychromatic coating compositions and thermochromic coating compositions. However, any of these coating films changes in hue and tone depending on the viewing angle, and cannot be adapted to the above needs.
Moreover, although the photosensitive coating composition which responds to the area | region of visible light to an ultraviolet-ray is disclosed by the following patent document 7-patent document 10, for example, these coating films are all for the resist use for printed wiring boards. Therefore, it does not have color developability.
In addition, it contains a photosensitive coloring composition containing polysilane and a leuco dye and develops color by ultraviolet exposure (see, for example, Patent Document 11), a coloring agent, a developer, a recording sensitivity improver, an aqueous binder, etc. Although a coloring marking material (for example, see Patent Document 12) that develops color with laser light has been disclosed, it is difficult to reproduce multiple colors in one layer, which is insufficient in terms of the hue and image storability of these colored products. There is a problem.

Separately, for example, the following Patent Documents 13 to 23 are disclosed as “thermal recording labels” attached to products and packages at supermarkets and convenience stores. In addition, for example, Patent Documents 24 to 29 listed below are disclosed as “thermosensitive color labels” for similar uses.
These “thermosensitive label” and “thermosensitive color label” are basically composed of a combination of a leuco dye, a basic dye, an electron donating compound, a color former and a developer as a label base material. A label sheet in which a heat-sensitive recording layer is formed, and an adhesive layer, a release layer, an intermediate layer, a protective layer, and the like are laminated depending on the purpose. From the same “thermosensitive recording label” and “thermosensitive coloring label”, only a single color hue or printed image can be obtained, and it is not possible to develop or record an arbitrary hue from one type of label material.

JP 2002-275422 A JP 2002-201423 A JP 2001-131486 A JP 2001-031911 A JP 2000-204296 A JP 2000-086943 A JP 2003-149805 A JP 2002-287345 A JP 2001-281854 A JP 2001-242620 A Japanese Patent Laid-Open No. 06-289528 JP 07-257042 A Japanese Patent Laid-Open No. 2002-362027 JP 2002-0667507 A Japanese Unexamined Patent Publication No. 2000-356552 JP 2000-010485 A JP-A-11-327445 JP 11-327441 A JP-A-11-249567 JP-A-11-245512 JP-A-11-231785 JP-A-10-105068 Japanese Patent Laid-Open No. 10-058829 JP 2002-036725 A JP 2001-353965 A JP 2000-158860 A JP-A-11-344929 JP 09-054550 A JP 09-054549 A

  The present invention has been made in view of the above situation, and while being substantially colorless before processing, after applying and drying, by applying heat energy from the outside by heating or heating, etc., It is an object of the present invention to provide a coating composition capable of color development or recording in an arbitrary hue and a thermal color recording method for the paint.

In order to achieve the above-mentioned problems, the present inventors diligently and researched about the composition of the paint, and as a result, have come to find the following paint composition of the present invention and a method for recording the thermal color of the paint. That is,
<1> Contains substantially colorless coloring component (a) and coloring component (b) that can form a dye by contacting and reacting with each other by applying thermal energy from the outside. Is a coating composition comprising a microcapsule, wherein the coating composition contains at least two kinds of microcapsules having different thermal sensitivities.
<2> The coating composition as described in <1> above, wherein the two or more types of microcapsules having different thermal sensitivities are colored in different hues.
<3> The coating composition as described in <1> or <2> above, wherein the difference in thermal sensitivity between the two or more types of microcapsules is 3 ° C. or more in the difference in color development start temperature during static color development. .
<4> The coating composition according to any one of <1> to <3>, wherein the wall material of the microcapsule is made of polyurethane and / or a polyurea polymer.
<5> The coating composition according to any one of <1> to <4>, further comprising an aqueous resin having a hydroxyl group.
<6> The coating composition according to any one of <1> to <5>, further comprising a resol type phenol resin.
<7> The above-mentioned <1>, wherein the coloring component (a) and the coloring component (b) are a photodegradable diazonium salt and a coupler compound, and the diazonium salt is encapsulated in a microcapsule. -The coating composition in any one of <6>.
<8> Relatively low thermal sensitivity before photodecomposing the diazonium salt encapsulated in microcapsules with relatively high thermal sensitivity into the coating film coated with the coating composition according to <7> above A thermochromic recording method characterized in that two or more mixed color images are formed by applying thermal energy capable of thermocoloring by a diazonium salt encapsulated in said microcapsule and a coupler.
<9> Thermal energy capable of thermal coloring with a diazonium salt and a coupler encapsulated in a microcapsule having the highest thermal sensitivity on a coating film coated with the coating composition according to <7> above (2) The diazonium salt is decomposed by exposure to light having a wavelength for decomposing the diazonium salt, and (3) the thermal sensitivity is second. A second thermochromic recording was performed in which a diazonium salt encapsulated in a high microcapsule and a coupler were applied to give heat energy capable of thermocoloring, and (4) the diazonium salt involved in the second color development was recorded. Thermal coloring recording method, characterized in that color development is recorded by repeating the procedure of coloring and fixing in the descending order of thermal sensitivity, in which the diazonium salt is decomposed by exposure to light of the wavelength to be decomposed .

  According to the present invention, there is provided a novel coating composition that can be colored or recorded in an arbitrary hue by applying heat energy from the outside to the coating film after drying, while being almost colorless before treatment. It became possible to do. Thus, for example, when multi-color (labeling) such as labels, seals, stickers, emblems for recognizing information and sorting articles is made, a multi-color article is manufactured using only one type of coating composition. And the like, and an extremely useful coating composition and a thermochromic recording method for the coating can be provided.

The coating composition of the present invention contains at least a substantially colorless coloring component (a) and a coloring component (b) that can react with each other to form a dye by applying thermal energy from the outside. A coating composition in which one of them is encapsulated in a microcapsule is characterized in that the coating composition contains at least two or more kinds of microcapsules having different thermal sensitivities.
The two or more types of microcapsules having different thermal sensitivities are preferably those that develop colors in different hues. Further, the difference in thermal sensitivity between the two or more types of microcapsules is 3 ° C. in the color development start temperature difference during static color development. The above is preferable.
Further, the wall material of the microcapsule as described above is preferably made of polyurethane and / or polyurea polymer.

  In particular, it is most preferable to use a combination of a photodegradable diazonium salt and a coupler compound, which will be described later, as the color forming components (a) and (b) and encapsulate one of them in a microcapsule. At this time, light of any wavelength in the infrared to visible to ultraviolet region can be used as the light to be irradiated. Among them, ultraviolet light is used for long-term storage and extensive color recording as a coating composition. This is desirable. As the heating or heating energy, an arbitrary amount of heat energy can be applied, but it is desirable to apply it within a range in which the formed dye does not decompose or discolor.

The coating composition of the present invention having the above-described configuration can develop a desired desired hue by irradiating a colorless or light-colored coating film that has been coated and dried with light of different wavelengths. Has new functions.
Hereinafter, although the main structure of the coating composition of this invention is demonstrated in detail, this invention is not limited to these description matters.

(Coloring component system)
The coloring component contained in the coating composition of the present invention is one that has excellent transparency when untreated and can form a dye by applying external thermal energy such as heating and heating. Any kind of compound can be used. Such a coloring component system includes a combination of a substantially colorless coloring component (a) and a substantially colorless coloring component (b) that reacts with the coloring component to form a dye, a so-called two-component type. The coloring component system is preferably exemplified, and either the coloring component (a) or the coloring component (b) is encapsulated in a microcapsule from the viewpoint of improving storage stability and suppressing background covering. Form. Examples of combinations constituting such a two-component color forming component system include the following (a) to (m).

(A) Combination of electron donating dye precursor and electron accepting compound (b) Combination of diazonium salt and coupler compound (c) Organometallic salt such as silver behenate and silver stearate, protocatechinic acid, spiroindane (D) A combination of a long-chain aliphatic salt such as ferric stearate or ferric myristate with a phenol such as gallic acid or ammonium salicylate (e) Acetic acid or stearin Combination of organic acid heavy metal salt such as acid, salt with nickel, cobalt, lead, copper, iron, mercury, silver etc. and alkaline earth metal sulfide such as calcium sulfide, strontium sulfide, potassium sulfide etc. Or a combination of the organic acid heavy metal salt and an organic chelating agent such as s-diphenylcarbazide or diphenylcarbazone. (F) Silver sulfide, lead sulfide, sulfide A combination of a (heavy) metal sulfate such as silver or sodium sulfide and a sulfur compound such as Na-tetrathionate, sodium thiosulfate or thiourea (g) an aliphatic ferric salt such as ferric stearate; A combination with an aromatic polyhydroxy compound such as 3,4-dihydroxytetraphenylmethane (h) an organic noble metal salt such as silver oxalate and mercury oxalate, and an organic polyhydroxy compound such as polyhydroxy alcohol, glycerin and glycol (I) Combination of an aliphatic ferric salt such as ferric pelargonate and ferric laurate and a thiocesylcarbamide or isothiocecilcarbamide derivative (j) Lead caproate, lead pelargonate, behen Combinations of organic acid lead salts such as lead acid and thiourea derivatives such as ethylenethiourea and N-dodecylthiourea (k) ferric stearate, steer A combination of a higher fatty acid heavy metal salt such as copper acid and a zinc dialkyldithiocarbamate (l) a compound that forms an oxazine dye such as a combination of resorcin and a nitroso compound (m) a formazan compound and a reducing agent and / or a metal salt Combination with

  Among the above, the coating composition of the present invention includes a coloring component system comprising (a) a combination of an electron donating dye precursor and an electron accepting compound, and (b) a combination of a diazonium salt and a coupler compound. The combination of the diazonium salt (b) and the coupler compound is particularly preferable.

Below, the combination of the said color-forming component system (a) and (b) preferably used for the coating composition of this invention is demonstrated in detail.
(A) Combination of electron-donating dye precursor and electron-accepting compound The electron-donating dye precursor preferably used in the present invention is not particularly limited as long as it is substantially colorless. Or has a property of accepting a proton such as an acid to develop a color, in particular, having a partial skeleton such as lactone, lactam, sultone, spiropyran, ester, amide, Those which are colorless compounds in which these partial skeletons rapidly open or cleave upon contact are preferred.

  Examples of the electron-donating dye precursor include triphenylmethane phthalide compounds, fluoran compounds, phenothiazine compounds, indolyl phthalide compounds, leucooramine compounds, rhodamine lactam compounds, and triphenylmethane compounds. Examples thereof include compounds, triazene compounds, spiropyran compounds, fluorene compounds, pyridine compounds, pyrazine compounds.

Specific examples of the phthalides include compounds described in U.S. Reissue Patent No. 23024, U.S. Pat. Nos. 3,491,111, 3,491,112, 3,491,116, and 3,509,174. .
Specific examples of the fluorans are described in U.S. Pat. Nos. 3,624,107, 3,627,787, 3,410,411, 3,462,828, 3,681,390, 3,920,510, 3,959,571, and the like. Compounds.
Specific examples of the spiropyrans include compounds described in US Pat. No. 3,971,808.
Examples of the pyridine-based and pyrazine-based compounds include compounds described in US Pat. Nos. 3,775,424, 3,853,869 and 4,246,318.
Specific examples of the fluorene compound include compounds described in JP-A-63-94878.
Among these, black-colored 2-arylamino-3- [H, halogen, alkyl, or alkoxy-6-substituted aminofluorane] is particularly preferably used.

  Specifically, for example, 2-anilino-3-methyl-6-diethylaminofluorane, 2-anilino-3-methyl-6-N-cyclohexyl-N-methylaminofluorane, 2-p-chloroanilino-3- Methyl-6-dibutylaminofluorane, 2-anilino-3-methyl-6-dioctylaminofluorane, 2-anilino-3-chloro-6-diethylaminofluorane, 2-anilino-3-methyl-6-N- Ethyl-N-isoamylaminofluorane, 2-anilino-3-methyl-6-N-ethyl-N-dodecylaminofluorane, 2-anilino-3-methoxy-6-dibutylaminofluorane, 2-o-chloroanilino -6-dibutylaminofluorane, 2-p-chloroanilino-3-ethyl-6-N-ethyl-N-isoamylaminophen Oran, 2-o-chloroanilino-6-p-butylanilinofluorane, 2-anilino-3-pentadecyl-6-diethylaminofluorane, 2-anilino-3-ethyl-6-dibutylaminofluorane, 2-o -Toluidino-3-methyl-6-diisopropylaminofluorane, 2-anilino-3-methyl-6-N-isobutyl-N-ethylaminofluorane, 2-anilino-3-methyl-6-N-ethyl-N -Tetrahydrofurfurylaminofluorane, 2-anilino-3-chloro-6-N-ethyl-N-isoamylaminofluorane, 2-anilino-3-methyl-6-N-methyl-N-γ-ethoxypropylamino Fluorane, 2-anilino-3-methyl-6-N-ethyl-N-γ-ethoxypropylaminofluorane, 2-anilino 3-methyl -6-N-ethyl--N-.gamma. propoxypropyl aminofluoran like.

Examples of the electron-accepting compound that reacts with the above-described electron-donating dye precursor include acidic substances such as phenol compounds, organic acids or metal salts thereof, oxybenzoic acid esters, and the like. And compounds described in Japanese Patent No. 291183.
Specifically, 2,2-bis (4′-hydroxyphenyl) propane (generic name: bisphenol A), 2,2-bis (4′-hydroxyphenyl) pentane, 2,2-bis (4′-hydroxy) -3 ', 5'-dichlorophenyl) propane, 1,1-bis (4'-hydroxyphenyl) cyclohexane, 2,2-bis (4'-hydroxyphenyl) hexane, 1,1-bis (4'-hydroxyphenyl) ) Propane, 1,1-bis (4′-hydroxyphenyl) butane, 1,1-bis (4′-hydroxyphenyl) pentane, 1,1-bis (4′-hydroxyphenyl) hexane, 1,1-bis (4′-hydroxyphenyl) heptane, 1,1-bis (4′-hydroxyphenyl) octane, 1,1-bis (4′-hydroxyphenyl) -2-methyl-pentane, 1, -Bis (4'-hydroxyphenyl) -2-ethyl-hexane, 1,1-bis (4'-hydroxyphenyl) dodecane, 1,4-bis (p-hydroxyphenylcumyl) benzene, 1,3-bis Bisphenols such as (p-hydroxyphenylcumyl) benzene, bis (p-hydroxyphenyl) sulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, bis (p-hydroxyphenyl) acetic acid benzyl ester;

Salicylic acid derivatives such as 3,5-di-α-methylbenzylsalicylic acid, 3,5-di-tertiarybutylsalicylic acid, 3-α-α-dimethylbenzylsalicylic acid, 4- (β-p-methoxyphenoxyethoxy) salicylic acid; Or a polyvalent metal salt thereof (in particular, zinc or aluminum is preferable); p-hydroxybenzoic acid benzyl ester, p-hydroxybenzoic acid-2-ethylhexyl ester, β-resorcinic acid- (2-phenoxyethyl) ester, etc. Oxybenzoates; phenols such as p-phenylphenol, 3,5-diphenylphenol, cumylphenol, 4-hydroxy-4'-isopropoxy-diphenylsulfone, 4-hydroxy-4'-phenoxy-diphenylsulfone Is mentioned.
Among these, bisphenols are particularly preferable from the viewpoint of obtaining good color development characteristics. Moreover, these electron-accepting compounds may be used individually by 1 type, and may use 2 or more types together.

(B) Combination of diazonium salt and coupler This photodegradable diazonium salt is a compound that causes a coupling reaction with a coupler compound, which will be described later, to produce a desired hue, and has a specific wavelength range before the reaction. It is desirable to be a photodegradable diazonium salt that decomposes when it receives light and no longer has a coloring ability even when a coupling component is present.
The hue in this color developing system is determined by a diazo dye formed by a reaction between a diazonium salt and a coupler compound. Therefore, by changing the chemical structure of the diazonium salt or coupler compound, the color hue can be arbitrarily changed, and a desired color hue can be obtained depending on the combination.

Examples of the photodegradable diazonium salt preferably used in the present invention include aromatic diazonium salts, and specific examples include aromatic diazonium salts, diazosulfonate compounds, diazoamino compounds, and the like.
The aromatic diazonium salt is preferably a diazonium salt represented by the following structural formula, but is not limited thereto. In addition, the aromatic diazonium salt is preferably used since it is excellent in light fixing property, generates little colored stain after fixing, and has a stable color developing portion.
Ar-N ₂ ⁺ · X ⁻
In the above formula, Ar represents a substituted or unsubstituted aromatic hydrocarbon ring group, N ₂ ⁺ represents a diazonium group, and X ⁻ represents an acid anion.

  In recent years, a large number of diazo sulfonate compounds have been known, which are obtained by treating each diazonium salt with a sulfite, and can be suitably used for the heat-sensitive recording material of the present invention.

The diazoamino compound can be obtained by coupling a diazo group with dicyandiamide, sarcosine, methyltaurine, N-ethylanthranic acid-5-sulfonic acid, monoethanolamine, diethanolamine, guanidine, etc. It can be suitably used for the heat-sensitive recording material of the invention.
Details of these diazonium salts are described in detail, for example, in JP-A-2-136286.

  On the other hand, examples of the coupler compound that undergoes a coupling reaction with the diazonium salt include those described in Japanese Patent Application Laid-Open No. Sho 62-146678, including 2-hydroxy-3-naphthoic acid anilide, resorcin, and the like. Can be mentioned.

In the present invention, when using a combination of a diazonium salt and a coupler compound as a color forming component system, these coupling reactions are carried out in a basic atmosphere from the viewpoint of further promoting the reaction. It is preferable to add a basic substance as a sensitizer.
Examples of the basic substance include water-insoluble or hardly soluble basic substances and substances that generate alkali by heating, such as inorganic or organic ammonium salts, organic amines, amides, urea, thiourea or derivatives thereof, Nitrogenous compounds such as thiazoles, pyrroles, pyrimidines, piperazines, guanidines, indoles, imidazoles, imidazolines, triazoles, morpholines, piperidines, amidines, forimazines or pyridines. .
Specific examples thereof include those described in JP-A No. 61-291183.

In the coating composition of the present invention, in order to ensure sufficient transparency, as the coloring component system, (a) a combination of the electron donating dye precursor and the electron accepting compound, or (b) a diazonium salt, It is preferable to use a combination of coupler compounds. Further, in the present invention, from the viewpoint of storage stability and background covering, either one of the coloring component (a) and the coloring component (b) is encapsulated in a microcapsule. In particular, the electron donating dye precursor or the photodegradable diazonium salt is preferably encapsulated in a microcapsule.
Furthermore, in the present invention, as the color developing component system encapsulated in each microcapsule, it is preferable to use those having different color hues and capable of photolysis, and also having different photolysis wavelengths.

(Microcapsule)
The coating composition of the present invention contains at least two or more kinds of microcapsules having different thermal sensitivities. As such microcapsules having different thermal sensitivities, for example, two or more types of microcapsules made of different types of wall materials such as glass transition temperatures (Tg) different from each other or different polarities are preferably used. It can also be obtained by changing various constituent factors such as the film thickness and particle diameter of the capsule wall and the reaction efficiency of the coloring component.
As for the microcapsules having different thermal sensitivities, the difference in thermal sensitivity is preferably 3 ° C. or more in the color development start temperature difference during static color development. Here, the color development start temperature difference at the time of static color development is the maximum when the color forming component (a) and the color forming component (b) come into contact with each other to form a dye by applying external heat energy. When a coated photosensitive material with a maximum color saturation saturation reflection density of 2.0 when energy is applied is produced, and the color development start temperature is compared with other photosensitive materials produced in the same manner, the color developed against the background density. The condition is that the temperature at which the concentration becomes +0.2 differs by 3 ° C. or more.
In addition, the coating composition of the present invention includes a plurality of coatings containing microcapsules with different heat sensitivity that develop colors in different hues, in addition to embodiments that include a plurality of types of microcapsules with different thermal sensitivity that develop colors with different hues. It may be an embodiment in which the layers are laminated and painted.

  Reactants that produce the polymeric material that forms the microcapsule walls are added to the inside of the oil droplets and / or to the outside of the oil droplets. Specific examples of such a polymer substance include, for example, polyurethane, polyurea, polyamide, polyester, polycarbonate, urea-formaldehyde resin, melamine resin, polystyrene, styrene methacrylate copolymer, styrene-acrylate copolymer, and the like. . Among them, preferred polymer materials are polyurethane, polyurea, polyamide, polyester and polycarbonate, and particularly preferred are polyurethane-urea copolymer polymers. As the polymer substance, two or more kinds can be used in combination.

  A microcapsule comprising a polyurethane-urea copolymer polymer preferably used in the present invention generally contains a diazo compound or an electron-donating dye precursor, and the capsule wall is obtained by polymerization of a polyfunctional isocyanate compound. Formed from the resulting polymer. As known polyfunctional isocyanate compounds, compounds described in JP-A-62-212190, JP-A-4-26189, JP-A-5-317694, JP-A-10-114153 and the like are referred to. be able to.

  As said polyfunctional isocyanate compound, the compound which has a trifunctional or more than trifunctional isocyanate group is preferable, and a bifunctional isocyanate compound can also be used. Specifically, xylene diisocyanate and its hydrogenated product, hexamethylene diisocyanate, tolylene diisocyanate and its hydrogenated product, and diisocyanates such as isophorone diisocyanate are used as the main raw materials, and these dimers or trimers (burette or isocyanate). Nurate), a polyfunctional adduct (adduct) between a polyol such as trimethylolpropane and a bifunctional isocyanate such as xylylene diisocyanate, a polyol such as trimethylolpropane and a bifunctional isocyanate such as xylylene diisocyanate Examples thereof include a compound obtained by introducing a high molecular weight compound such as polyether having active hydrogen such as polyethylene oxide into the adduct, and a formalin condensate of benzene isocyanate.

  The amount of the polyvalent isocyanate compound used is appropriately determined so that the average particle diameter of the microcapsules is 0.05 to 10 μm and the wall thickness is 0.005 to 1.0 μm. About 0.1 to 10 μm is common.

  The capsule wall of the microcapsule is made of a polymer obtained by polymerization of a polyfunctional isocyanate compound, and the polymerization of the polyfunctional isocyanate compound is performed, for example, by reaction with a compound having two or more active hydrogen atoms in the molecule. It is preferable. Examples of such a compound having an active hydrogen atom include, for example, water, polyhydric alcohol compounds such as ethylene glycol and glycerin, polyhydric amine compounds such as ethylenediamine and diethylenetriamine, and mixtures thereof. It is done. Among these, it is preferable to perform polymerization using water, but water, alcohol, and amines may be used in combination as necessary. As a result of this, a capsule wall made of polyurethane / polyurea wall is formed.

In addition, the glass transition temperature (Tg) of the capsule wall is adjusted by adjusting the kind of polyfunctional isocyanate compound, the amount of polyhydric alcohol compound or polyamine amine compound added, the reaction temperature, and the reaction time. However, there is a practical limit on the upper limit of the addition amount, the reaction temperature and the reaction time, and it is desirable to adjust the Tg greatly by selecting an optimal capsule wall material.
Here, in this specification, the glass transition temperature (Tg) of the capsule wall of the microcapsule is measured using a glass transition temperature measuring device (trade name “DMTA (Dynamic Mechanical Thermal Analyzer)) manufactured by Polymer Laboratory. is there.

  For example, when producing a microcapsule wall having a low glass transition temperature, for example, 30% by mass of a polyisocyanate represented by the following isocyanate compound (1) and a polyisocyanate represented by the following isocyanate compound (2) A mixture of, for example, 70% by weight of a narate can be suitably used. On the other hand, when a microcapsule wall having a high glass transition temperature is used, for example, 100 of a polyisocyanate represented by the following isocyanate compound (2) is used. % By weight can be used.

  In the present invention, it is also possible to control Tg by adding a compound that lowers the glass transition temperature (Tg) of the microcapsule wall. Such an additive is also called a sensitizer and can be selected from polymer plasticizers used as microcapsule walls, and it is preferable to select and use one having a melting point of 120 ° C. or lower.

  Examples of the additive include, when the wall material is a polyurethane-urea copolymer polymer, organic sulfonamide compounds, aliphatic amide compounds, arylamide compounds, phenolic compounds, alcoholic compounds, and the like. Examples thereof include compounds such as hydroquinone dihydroxyethyl ether, xylylene diol, N-hydroxyethyl-methanesulfonic acid amide, and N-phenyl-methanesulfonic acid amide. These may be contained in the core substance, or may be added outside the microcapsule as an emulsified dispersion.

  As described above, capsule wall materials having different glass transition temperatures (Tg) can be arbitrarily used to form microcapsules having different thermal sensitivities or Tg. As the microcapsules used in the present invention, the Tg Is preferably in the range of 10 ° C to 250 ° C, more preferably in the range of 20 ° C to 200 ° C, and most preferably in the range of 30 ° C to 100 ° C. If the difference in Tg is within the range of 10 ° C. to 250 ° C., the color development effect due to the temperature difference can be sufficiently exerted, a vivid hue can be reproduced, and the required thermal energy becomes too high. There is no harmful effect.

  For production of microcapsules, any of an interfacial polymerization method, an internal polymerization method, and an external polymerization method can be adopted. In particular, an aqueous solution in which a core substance containing a coloring component is dissolved in a water-soluble polymer is used. It is preferable to employ an interfacial polymerization method in which after emulsification in the medium, a wall of a polymer substance is formed around the oil droplets. Reactants that form the polymeric material are added to the inside and / or outside of the oil droplets.

  Details of the manufacturing method of the microcapsule composite wall are described in, for example, Japanese Patent Application Laid-Open No. 58-66948. When the aforementioned photodegradable diazonium salt or electron donating dye precursor is encapsulated in a microcapsule, it is preferable to use the photodegradable diazonium salt or electron donating dye precursor dissolved in an organic solvent.

  As such an organic solvent, low-boiling solvents such as ethyl acetate, methyl acetate, carbon tetrachloride, chloroform, dioxane, acetone, and benzene are preferable. Such an organic solvent is described in detail in JP-A-4-19778.

  The organic solvent used in this case can be appropriately selected from, for example, high-boiling oils described in JP-A-2-141279. Among these high-boiling oils, it is preferable to use esters from the viewpoint of the stability of the emulsified dispersion, and in particular, when tricresyl phosphate is used alone or in combination, the dispersion stability of the coupler is good. It is. Here, the oils described above or other oils can be used in combination.

  In the present invention, an auxiliary solvent can be added to the above organic solvent as a dissolution aid having a lower boiling point. Preferred examples of such auxiliary solvents include ethyl acetate, isopropyl acetate, butyl acetate, and methylene chloride. In some cases, it is possible to use only a low-boiling auxiliary solvent without containing a high-boiling oil. The water-soluble polymer to be incorporated as a protective colloid in the aqueous phase mixed with the oil phase containing these components can be appropriately selected from known anionic polymers, nonionic polymers, and amphoteric polymers. Among them, polyvinyl alcohol, gelatin, cellulose derivatives and the like are preferable.

  In addition, a charge-controlling agent such as a metal-containing dye or nigrosine and other additives may be added to the microcapsule wall used in the present invention as necessary. These additives can be added at any time before or at the time of wall formation. Further, in order to adjust the charge on the microcapsule wall surface, a vinyl monomer or the like may be added and the monomer may be graft polymerized.

The step of emulsifying and dispersing the core material containing the coloring component in the aqueous solution in which the water-soluble polymer is dissolved is appropriately selected from known emulsifying and dispersing devices such as a homogenizer, a manton gorey, an ultrasonic disperser, a dissolver, and a teddy mill. Can be done.
After emulsification and dispersion, the emulsified dispersion is usually heated to 30 to 70 ° C. for the purpose of promoting the capsule wall formation reaction. Further, during the reaction, in order to prevent aggregation between the capsules, it is necessary to add water to reduce the collision probability between the capsules or to perform sufficient stirring. Further, a dispersion stabilizer for preventing aggregation may be added during the reaction.
In the polymerization reaction of isocyanate, the generation of carbon dioxide gas is observed as the reaction proceeds, and the end thereof can be regarded as the end point of the capsule wall formation reaction. Usually, by reacting for several hours, microcapsules encapsulating the target diazonium salt compound and the like can be obtained.

  The microcapsules manufactured as described above are not destroyed by heat or pressure. When the microcapsule wall is heated to a temperature higher than the glass transition temperature, the material permeability of the wall increases, and the inside and outside of the core of the microcapsule increases. Has a thermal sensitivity control action such that the coloring component contained in the color passes through the microcapsule wall and develops color.

  In the present invention, the components that are not encapsulated in the microcapsules may be solid-dispersed as usual. In particular, from the viewpoint of improving the transparency of the coating film and improving the quality of the color image, coupler compounds and electronic components are used. After dissolving a receptive compound or the like in a water-insoluble or insoluble organic solvent, it contains a water-soluble polymer as a protective colloid and, if necessary, is mixed with an aqueous phase containing a surfactant. It is preferably used in the form of an emulsified dispersion emulsified and dispersed.

  The water-soluble polymer to be incorporated as a protective colloid in the aqueous phase mixed with the oil phase containing these components can be appropriately selected from known anionic polymers, nonionic polymers, and amphoteric polymers. However, polyvinyl alcohol, gelatin, cellulose derivatives and the like are particularly preferable. As the surfactant to be contained in the aqueous phase, an anionic or nonionic surfactant that does not cause precipitation or aggregation by acting with the protective colloid can be appropriately selected and used. Preferred surfactants include sodium alkylbenzene sulfonate, sodium alkyl sulfate, dioctyl sulfosuccinate sodium salt, polyalkylene glycol (for example, polyoxyethylene nonyl phenyl ether) and the like.

  The emulsified dispersion in the present invention uses an oil phase containing the above components, a protective colloid, and, if necessary, an aqueous phase further containing a surfactant for normal fine particle emulsification such as high-speed stirring and ultrasonic dispersion. It can be easily obtained by mixing and dispersing by using the means to be used. The ratio of oil phase to water phase (oil phase mass / water phase mass) is preferably 0.02 to 1.2, more preferably 0.1 to 0.7. In the range of 0.02 to 1.2, the aqueous phase is too dilute so that sufficient color developability cannot be obtained, and conversely, the stability of the emulsion is not lowered.

(Thermo color recording method)
The coating composition of the present invention encloses in a microcapsule any one of a substantially colorless coloring component (a) and a coloring component (b) that can form a pigment by contacting and reacting with each other, and at least Since it contains two or more kinds of microcapsules having different thermal sensitivities, a painted and dried colorless coating film can be developed or recorded in any desired hue.
In particular, the coating composition of the present invention containing a diazonium salt as the color-forming component and containing at least two or more kinds of microcapsules having different thermal sensitivities is excellent in storage stability and surface covering, and has a light having a different wavelength. By decomposing the diazonium salt, it is possible to develop a clear color in any desired hue and to provide a useful coating composition because of excellent image storage stability.

  When the coating film coated with the coating composition of the present invention is heated at an arbitrary temperature with a heat roller or the like, the capsule wall of the microcapsule softens, and the coupler compound or basic compound outside the capsule enters the capsule and develops color. To do. At this time, prior to the above heating, when an arbitrary amount of light is irradiated with light that approximately matches the absorption spectrum of the arbitrary diazonium salt used in the coating composition, a part or all of the diazonium salt decomposes and the coupler compound Thus, it is possible to adjust to any color hue. Further, after the color development, the colored image is reliably fixed by irradiating the entire surface with the light having the absorption wavelength of the diazonium salt again.

  Here, as a light source used for hue adjustment and fixing, various fluorescent lamps, xenon lamps, mercury lamps, LEDs, and the like are used, and this emission spectrum substantially matches the absorption spectrum of the diazonium salt used in the coating composition. It is preferable that hue can be adjusted and fixed efficiently. In the present invention, a light source having an emission center wavelength of 300 to 440 nm is particularly preferable.

  The multicolor coloring paint composition of the present invention includes a coloring component system containing a diazonium salt having a maximum absorption wavelength of 320 ± 20 nm and a coupler that reacts with the diazonium salt to develop a color, and a maximum absorption wavelength of 360 ± 20 nm. A coloring component system comprising a certain diazonium salt and a coupler which reacts with the diazonium salt and colors, and a coloring component system comprising a diazonium salt having a maximum absorption wavelength of 400 ± 20 nm and a coupler which reacts with the diazonium salt and colors The aspect containing these is preferable.

  The multicolor coloring coating composition of the present invention includes (1) a coupler that reacts with a diazonium salt having a maximum absorption wavelength of 320 ± 20 nm, a diazonium salt having a maximum absorption wavelength of 360 ± 20 nm, and both of the diazonium salts. Or (2) a combination of a diazonium salt having a maximum absorption wavelength of 360 ± 20 nm, a diazonium salt having a maximum absorption wavelength of 400 ± 20 nm, and a coupler that reacts with both diazonium salts to develop a color. Preferred as a coating composition.

Hereinafter, a method for obtaining a good color recording image using the coating composition of the present invention will be specifically described.
The thermochromic recording method of the present invention is a method in which a relatively low heat is applied to a coating film coated with the coating composition described above before photo-decomposing the diazonium salt encapsulated in microcapsules having relatively high thermal sensitivity. Two or more kinds of mixed color images can be formed by applying thermal energy capable of thermal coloring with a diazonium salt encapsulated in a sensitive microcapsule and a coupler.

  In addition, the coating film coated with the coating composition of the present invention is applied with (1) thermal energy capable of thermal coloring with a diazonium salt and a coupler encapsulated in a microcapsule having the highest thermal sensitivity. After performing the first thermochromic recording, (2) the diazonium salt is decomposed by exposure to light having a wavelength for decomposing the diazonium salt, and then (3) encapsulated in a microcapsule having the second highest thermal sensitivity. A second thermochromic recording is performed by applying thermal energy capable of thermocoloring by the diazonium salt and the coupler, and (4) light having a wavelength for decomposing the diazonium salt involved in the second coloring. Color development recording is performed by repeating the procedure of color development and fixing in which the diazonium salt is decomposed by exposure in accordance with the descending order of thermal sensitivity.

As one embodiment, a microcapsule (A) (hereinafter referred to as a magenta coloring capsule) encapsulating a magenta coloring diazonium salt and having a highly thermosensitive capsule wall, and a cyan coloring coloring diazonium salt are included, and the thermal sensitivity is low. For a coating composition containing microcapsules (B) composed of capsule walls (hereinafter referred to as cyan coloring capsules), for example, thermal coloring recording can be performed as follows.
That is, the step (A) is a step of completely coloring the magenta coloring capsule with relatively low heat energy. Further, the step (B) is a step of fixing using a light source of a specific wavelength that selectively photodecomposes only the diazonium salt of the magenta color capsule. Furthermore, the step (C) is a step of completely coloring the cyan coloring capsule with higher heat energy than the above. In addition, a process of fixing using a light source having a specific wavelength that selectively photodecomposes only the diazonium salt of the cyan coloring capsule is referred to as a process (D).
In this case, after step (A), when step (B) and further step (C) (and step (D) if necessary) are performed, step (A) and step (B) are not performed. , (C) (and (D) if necessary), both of them develop blue, which is a mixed color of magenta and cyan. In addition, when step (C) (and step (D) if necessary) is performed after step (B), the color is changed to cyan.
On the other hand, when the step (A) (and the step (B) if necessary) is performed after the step (D), the color is magenta. Further, after step (B) and step (D), even if step (C) is performed, no color is generated and the color becomes white. However, in the above example, the applied heat energy causes each dye to develop color completely, and the hue and shade are adjusted in various ways by developing only a part of the dye depending on the applied heat energy and the degree of light fixing. Is possible.

(Water-based paint)
As the coating composition of the present invention containing the coloring component system described above, an aqueous coating containing an aqueous resin having a hydroxyl group as a binder (binder) is desirable from the viewpoint of working environment and resource saving.

(1) Aqueous resin having a hydroxyl group As the aqueous resin having a hydroxyl group used in the present invention, water-soluble or water having at least two OH groups in the molecule and having a hydroxyl value of 10 to 300 per resin solid content. A dispersible resin can be mentioned. Specific examples of such an aqueous resin include epoxy resins, acrylic resins, polyether resins, polyester resins, and urethane resins.

The epoxy resin used as the aqueous resin of the present invention is a resin having two or more epoxides in the molecule and a product obtained by reacting this with a fatty acid, dibasic acid, bisphenol A, F or B to partially leave the epoxide. And those obtained by reacting a polybasic acid, phosphoric acid or a condensate thereof. Among these, an epoxy resin obtained by condensing an epihalohydrin with bisphenol A, F, or B in the presence of an alkaline catalyst is preferable because it has excellent mechanical strength, adhesion, chemical resistance, and the like of the coating film. . The number average molecular weight of the epoxy resin is 300 or more, preferably 1000 or more.
Examples of the fatty acid include vegetable oil fatty acids such as dehydrated castor oil, soybean oil, cottonseed oil, safflower oil, tall oil, castor oil, coconut oil, and palm oil. Examples of the dibasic acid include maleic acid and fumaric acid. Examples of the polybasic acid include (anhydrous) trimellitic acid and (anhydrous) pyromellitic acid. Examples of the phosphoric acid condensate include polyphosphoric acid and anhydrous phosphoric acid. These fatty acids can be used alone or in a mixture and / or a mixture with a dibasic acid.

The acrylic resin used as the aqueous resin of the present invention is preferably a copolymer comprising an unsaturated monobasic carboxylic acid such as acrylic acid or methacrylic acid and another copolymerizable monomer. Such an acrylic resin is usually obtained by copolymerizing both monomers in an organic solvent at a temperature of 80 to 150 ° C. using a free radical generator such as benzoyl peroxide or asobisisobutyronitrile as a polymerization initiator. Examples of the copolymerizable monomer include, for example, (meth) acrylic acid alkyl ester, styrene monomer, hydroxyl group-containing monomer, N-substituted (meth) acrylamide, oxirane group-containing monomer, maleic acid dialkyl ester, and dialkyl fumarate. An ester, an acrylonitrile, etc. are mentioned, Among these, 1 type (s) or 2 or more types can be used together.
The content of unsaturated monobasic carboxylic acid in the acrylic resin is preferably 5 to 50% by mass, more preferably 10 to 30% by mass. When the content of the carboxylic acid is less than 5% by mass, the dispersion stability in the aqueous medium, the adhesion of the coating film to the substrate and the flavor retention may be lowered depending on the application. When the content of the carboxylic acid exceeds 50% by mass, the hot water resistance and retort resistance of the coating film decrease.
In addition, as for the number average molecular weight of the said acrylic resin, 3000-80000 are preferable. When the molecular weight is less than 3000, the workability is lowered, and when the molecular weight exceeds 80000, the solid content at an appropriate coating viscosity may be lowered.

When the epoxy resin is modified with the acrylic resin, the content of the unsaturated monobasic carboxylic acid in the acrylic resin is preferably 12 to 70% by mass, more preferably 25 to 60% by mass. It is preferable to use the acrylic resin in the range of 1/10 to 1/1 in terms of the solid content to the epoxy resin. When the content of the unsaturated monobasic carboxylic acid is less than 12% by mass, the flavor retention and the like may be lowered depending on the dispersion stability in the aqueous medium, the adhesion of the coating film to the substrate and the application. When the content of the carboxylic acid exceeds 70% by mass, the hot water resistance and retort resistance of the coating film may be lowered. When the solid mass ratio of the acrylic resin and the epoxy resin is less than 1/10, the dispersion stability of the coating composition is lowered, and when it exceeds 1/1, the corrosion resistance may be lowered.
The acrylic resin-modified epoxy resin can be produced by previously synthesizing an epoxy resin mono (meth) acrylate and then copolymerizing a copolymerizable monomer in addition to the above-described method. It can also be produced by copolymerizing the unsaturated monobasic carboxylic acid and another copolymerizable monomer in an epoxy resin solution. Here, the modified epoxy resin by the acrylic resin is one in which the radical active hydrogen in the epoxy resin is extracted and the acrylic resin is graft-bonded to the epoxy resin, a bond obtained by partial reaction of the epoxide and carboxyl, and the tertiary amine opens the epoxide. Including those cyclized and carboxylated with quaternary salts.

  Polyether resins used as the aqueous resin of the present invention include polyhydric carboxylic acids such as (anhydrous) phthalic acid, (anhydrous) maleic acid, (anhydrous) trimellitic acid, (anhydrous) pyromellitic acid, ethylene glycol, neo Low condensation products of polyhydric alcohols such as pentyl glycol, trimethylol propane and pentaerythritol, olefin oxides such as ethylene oxide and propylene oxide and / or polyalkylene glycols such as polyethylene glycol and polypropylene glycol, if necessary toluene diisocyanate, hexamethylene diisocyanate And those obtained by reacting a polyvalent isocyanate such as isophorone diisocyanate and / or a polyvalent carboxylic acid and / or an epoxy resin.

  The polyester resin used as the aqueous resin of the present invention is a polyhydric alcohol, if necessary, a monohydric alcohol such as octyl alcohol or nonyl alcohol, and a polycarboxylic acid, and if necessary, benzoic acid, coconut oil fatty acid, etc. Examples thereof include a monovalent carboxylic acid condensate and / or a product obtained by further reacting this with a polyvalent carboxylic acid.

  The urethane resin used as the aqueous resin of the present invention is a polyisocyanate and a polycondensation product of polyhydric alcohol and polycarboxylic acid, polyhydric isocyanate and amino alcohol such as methylethanolamine, diethanolamine and triethanolamine, if necessary, What reacted with the epoxy resin etc. are mentioned.

  When the hydroxyl value of the aqueous resin having a hydroxyl group used in the present invention is less than 10, curability may be insufficient. On the other hand, when the hydroxyl value exceeds 300, water resistance and corrosion resistance may be lowered. As said hydroxyl value, 30-250 are more preferable.

In the present invention, examples of a method for water-solubilizing or water-dispersing an aqueous resin having a hydroxyl group include the following methods. (1) A method of emulsifying with a surfactant, (2) A method of completely neutralizing or partially neutralizing an acid group such as a carboxyl group, a sulfonic acid group and a phosphate group in an aqueous resin with an alkali such as amine or ammonia, 3) A method in which an acid group such as an amino group in an aqueous resin is completely neutralized or partially neutralized with an acid such as formic acid or acetic acid, and (4) a method in which an ether bond having a high water affinity is introduced into the aqueous resin.
In the above method, (1) and (2), (1) and (3), (1) and (4), (2) and (4), (3) and (4), (1) Water-solubilization or water-dispersion can also be achieved by combinations of (2) and (4) and (1), (3) and (4).

(2) Resol-type phenolic resin In the coating composition of the present invention, the above-mentioned aqueous resin is used as a main binder, and further, adhesion to a substrate, mechanical strength, crosslinkability, corrosion resistance, weather resistance, heat resistance. From the viewpoint of improving water resistance, film residue resistance, storage stability, processing workability, and the like, it is desirable to use a water-soluble or water-dispersible resol type phenol resin in combination.
Such a resol type phenolic resin is a phenolic resin or a modified phenolic resin having 0 to 3 methylol groups (—CH ₂ OH) per benzene nucleus. For example, the following phenolic resins are preferable.
(A) Number average molecular weight obtained by reacting a diglycidyl ether type epoxy resin having a number average molecular weight of 300 to 2000, a phenol compound containing two phenolic hydroxyl groups in the molecule, a secondary monoamine compound, and a polyhydric phenol resin. Is a 1000-10000 aqueous resin.

(B) A resol type phenol resin having a number average molecular weight of 200 to 2000 and an average number of methylol groups per benzene nucleus of 0.3 to 3.0.
(C) An aqueous resin obtained by reacting an isocyanate-terminated urethane prepolymer obtained by reacting a diisocyanate, a polyol and a carboxyl group-containing diol with a polyphenol resin and / or a phenoxy resin, followed by neutralization with a tertiary amine and water dispersion. .
(D) Specific resol type phenolic resins described in JP-A-11-266938 and JP-A-11-217538.

(E) For cross-linking consisting of a resol type phenol-formaldehyde resin obtained by condensation reaction of bisphenols alone or phenols in which bisphenols are mixed with phenol and p-substituted monohydric phenol and formaldehyde in the presence of a catalyst. resin.
(F) A reaction product resin in the presence of a basic catalyst of a specific phenol compound and a monoepoxy compound described in JP-A-08-337740.
(G) A modified resole-type phenol resin obtained by subjecting a modified epoxy resin introduced with an oxyphenyl group and a resol-type phenol resin to a condensation reaction in the absence of a catalyst or an acidic catalyst.
(H) A resol type phenol resin obtained by reacting a specific alkylphenol and dihydric phenol described in JP-A No. 05-171102 with formaldehyde in two steps as required in the presence of an alkali catalyst.

  The aqueous coating composition of the present invention is in a dissolved or dispersed state in an aqueous medium. This aqueous medium means a water alone system or a mixture with an organic solvent in which at least 10% by mass of the medium is water. To do. Here, as the organic solvent as the aqueous medium, alkyl alcohols such as methanol, ethanol, isopropanol, and n-butanol, ketones such as acetone, methyl ethyl ketone, and isoamyl ketone can be used.

  The preferred blending ratio of the (1) hydroxyl group-containing aqueous resin and (2) resol type phenol resin used in the present invention is (1) aqueous resin / (2) phenol resin = 100 / 0.3 to 100/50 (mass). Ratio), and more preferably 100 / 0.5 to 100/30. If the blending ratio is less than 100 / 0.3, the effect of improving the corrosion resistance, adhesion, workability, etc. of the coating film may be insufficient. If the blending ratio exceeds 100/50, the coating ratio may be insufficient. The amount of water elution from the film increases, and the corrosion resistance and water resistance may decrease.

  In the present invention, examples of the mixing method of the aqueous resin having (1) hydroxyl group and (2) resol type phenol resin include the following methods. (A) An aqueous solution of acid or base is added to a mixture of an aqueous resin having a hydroxyl group and a phenol resin synthesized in advance in a solvent and stirred. (B) An aqueous solution of an acid or base is added to an aqueous resin having a hydroxyl group synthesized beforehand in a solvent and stirred, and then a phenol resin is added. (C) An aqueous resin having a hydroxyl group synthesized beforehand in a solvent and a phenol resin are precondensed at a temperature of 50 ° C. to 100 ° C. for about 10 minutes to 3 hours, and then an acid or base aqueous solution is added thereto and stirred. Here, the amount of the organic solvent can be reduced by subjecting the aqueous solution or aqueous dispersion to reduced pressure or atmospheric steam distillation to azeotrope the organic solvent with water.

  The coating composition of the present invention can be put into practical use by blending various additives, fillers, and the like suitable for the application within a range that does not impair the function or characteristics of the coating composition. Furthermore, various usual adjusting agents, for example, an antifoaming agent, a surface tension adjusting agent, a lubricant, etc. can also be mix | blended. Moreover, it is desirable to add the above additives before the solvent removal operation.

  The coating composition of the present invention includes a steel sheet, a plated steel sheet obtained by plating a surface of the steel sheet with one or more metals such as zinc, tin, chromium, nickel, and aluminum, or a surface thereof. In addition to paper substrates such as acid paper, neutral paper, coated paper, resin-coated paper, and synthetic paper, polymer substrates such as resin films and acrylic plates, which have been chemically or electrolytically treated with chromic acid, phosphoric acid, etc. Various substrates such as a metal substrate such as an aluminum plate or an iron plate can be used. It can also be applied to the coating of wood, molded resin, molded ceramics and the like.

As a coating method of the coating composition of the present invention, generally known methods can be used. That is, air spray, airless spray, brush coating, electrostatic spray, dip coating, bar coater, flow coater, roll coater, and electrodeposition coating.
Moreover, as drying conditions of the coating composition of this invention, the range whose temperature is 40-80 degreeC and time is several minutes-30 minutes are desirable.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these Examples. In the following examples, “part” and “%” all represent “part by mass” and “mass%” unless otherwise specified.

[Example 1]
(Preparation of phthalated gelatin aqueous solution)
Phthalated gelatin (trade name “MGP gelatin” manufactured by Nippi Collagen Co., Ltd.) 32 parts, 1,2-benzothiazolin-3-one (manufactured by Daito Chemical Industry Co., Ltd., 3.5% methanol solution) 91 parts and 367 parts of water were mixed and dissolved by heating to a temperature of 40 ° C. to obtain a phthalated gelatin aqueous solution.

(Preparation of alkali-treated gelatin aqueous solution)
25.5 parts of alkali-treated low ion gelatin (trade name “# 750 gelatin” manufactured by Nitta Gelatin Co., Ltd.), 1,2-benzothiazoline-3-one (manufactured by Daito Chemical Industry Co., Ltd., 3.5 % Methanol solution) 0.73 parts, calcium hydroxide 0.15 parts and water 144 parts were mixed and dissolved by heating to a temperature of 50 ° C. to obtain an alkali-treated gelatin aqueous solution.

(Preparation of thermoresponsive microcapsule solution (a))
To 10.6 parts of ethyl acetate, 3.2 parts of the following diazonium salt compound (A), 5.3 parts of monoisopropylbiphenyl, 1.4 parts of tricresyl phosphate, lucillin “TPO-L” (manufactured by BASF Japan Ltd.) ) 0.64 part, dibutyl sulfate 1.8 part, and calcium dodecylbenzenesulfonate (trade name “Pionin A-41C” manufactured by Takemoto Yushi Co., Ltd., 70% methanol solution) 0.06 part, temperature It heated to 40 degreeC and melt | dissolved uniformly. As a capsule wall material in this mixed solution, 1.8 parts of xylylene diisocyanate / trimethylolpropane adduct (trade name “Takenate D110N”, 75% ethyl acetate solution manufactured by Mitsui Takeda Chemical Co., Ltd.) and xylylene diisocyanate / tri 2.7 parts of a mixture of methylolpropane adduct and xylylene diisocyanate / bisphenol A adduct (trade name “Takenate D119N”, 50% ethyl acetate solution manufactured by Mitsui Takeda Chemical Co., Ltd.) are added and stirred uniformly. An oil phase mixture was obtained.

Separately, 49.5 parts of the phthalated gelatin aqueous solution were mixed with 18.9 parts of water and 0.43 part of sodium dodecylbenzenesulfonate (trade name “Neopelex G-15” manufactured by Kao Corporation, 15% aqueous solution). The mixture was added and mixed to obtain an aqueous phase mixture.
The above oil phase mixture was added to this aqueous phase mixture and emulsified and dispersed for 10 minutes at a temperature of 40 ° C. and a rotation speed of 10,000 rpm using a homogenizer manufactured by Nippon Seiki Seisakusho. After 24 parts of water was added to the resulting emulsion and homogenized, the mixture was stirred at a temperature of 40 ° C. for 3 hours to carry out an encapsulation reaction while removing ethyl acetate. Thereafter, 3.2 parts of ion exchange resin “Amberlite IRA68” (manufactured by Organo Corp.) and 6.4 parts of “Amberlite IRC50” (manufactured by Organo Corp.) were added and further stirred for 1 hour. Thereafter, the ion exchange resin was removed by filtration, and the concentration was adjusted so that the solid content concentration of the capsule solution was 20% to obtain a heat-responsive isotropic microcapsule solution (a) enclosing a diazonium salt.
Here, the glass transition temperature of the wall material of the thermally responsive isocapsule microcapsule (a) was about 112 ° C. when measured using a measuring apparatus “DMTA” manufactured by Polymer Laboratory.

(Preparation of thermoresponsive microcapsule solution (b))
In the preparation of the thermoresponsive microcapsule liquid (a), as a capsule wall material, xylylene diisocyanate / trimethylolpropane adduct (trade name “Takenate D110N” manufactured by Mitsui Takeda Chemical Co., Ltd.), 75% ethyl acetate solution ) 7.2 parts and 1.8 parts of polymethylene polyphenyl polyisocyanate (trade name “Millionate MR-200” manufactured by Nippon Polyurethane Industry Co., Ltd.) were added to prepare an oil phase mixture, In the same manner as in the capsule liquid (a), a thermoresponsive isocapsule liquid (b) containing a diazonium salt was prepared.
Here, the glass transition temperature of the wall material of the thermally responsive isocapsule microcapsule (b) was about 140 ° C. when measured using a measuring apparatus “DMTA” manufactured by Polymer Laboratory.

(Preparation of thermoresponsive microcapsule solution (c))
In the preparation of the thermoresponsive microcapsule liquid (a), the same procedure as in the capsule liquid (a) except that the following diazonium salt compound (B) was used instead of the diazonium salt compound (A). Then, a thermoresponsive microcapsule liquid (c) containing a diazonium salt was prepared. Here, the glass transition temperature of the wall material of the thermoresponsive microcapsule (c) was about 109 ° C. when measured using a measuring apparatus “DMTA” manufactured by Polymer Laboratory.

(Preparation of thermoresponsive microcapsule solution (d))
In the preparation of the thermoresponsive microcapsule liquid (b), the same procedure as in the capsule liquid (b) except that the following diazonium salt compound (B) was used instead of the diazonium salt compound (A). Then, a thermoresponsive microcapsule liquid (d) containing a diazonium salt was prepared. Here, the glass transition temperature of the wall material of the heat-responsive isocapsule microcapsule (d) was about 138 ° C. when measured using a measuring device “DMTA” manufactured by Polymer Laboratory.

(Preparation of coupler compound emulsion dispersion)
36.7 parts of ethyl acetate, 11.0 parts of the following coupler compound (C), 11.5 parts of triphenylguanidine (manufactured by Hodogaya Chemical Co., Ltd.), 4,4 '-(m-phenylenediisopropylidene) di Phenol (trade name “Bisphenol M” manufactured by Mitsui Petrochemical Co., Ltd.) 23.1 parts, 3,3,3 ′, 3′-tetramethyl-5,5 ′, 6,6′-tetra (1-propyloxy ) -1,1′-spirobisindane 3.7 parts, 4- (2-ethylhexyloxy) benzenesulfonic acid amide (manac Co., Ltd.) 15.1 parts, 4-n-pentyloxybenzenesulfonic acid amide ( 7.6 parts of Manac Co., Ltd.) and 4.7 parts of calcium dodecylbenzenesulfonate (trade name “Pionin A-41-C”, 70% methanol solution manufactured by Takemoto Yushi Co., Ltd.), Oil phase mixing A liquid was obtained.

Separately, 229 parts of water was added to 113 parts of the alkali-treated gelatin aqueous solution to obtain an aqueous phase mixture.
The above oil phase mixture was put into this aqueous phase mixture, and emulsified and dispersed at a temperature of 40 ° C. and a rotation speed of 10,000 rpm for 5 minutes using a homogenizer manufactured by Nippon Seiki Seisakusho. The obtained emulsion was heated to remove ethyl acetate, and then the concentration was adjusted so that the solid content concentration of the emulsion was 23% to obtain a coupler compound emulsion dispersion.

(Preparation of hydroxyl group-containing aqueous resin emulsion dispersion)
A mixture of 10 parts of 2-hydroxyethyl acrylate, 48 parts of styrene, 28 parts of ethyl acrylate, 5 parts of methacrylic acid, 60 parts of n-butanol and 2 parts of benzoyl peroxide was used in a flask in which 1/4 of the mixture was replaced with nitrogen. The temperature was heated to 80 ° C., and the remaining 3/4 amount was gradually dropped over 3 hours. Next, a mixture of 0.2 parts of benzoyl peroxide and 5 parts of n-butanol was added dropwise over 30 minutes. After the completion, the mixture was stirred at the same temperature for 1 hour, and then a mixture of 5 parts of dimethylaminoethanol and 150 parts of water was gradually added. In addition, an acrylic resin emulsion dispersion was obtained as an aqueous resin emulsion dispersion having a hydroxyl group.

(Preparation of resol type phenol resin solution)
15 parts of pt-butylphenol, 30 parts of 35% formalin and 30 parts of 25% aqueous calcium hydroxide solution were mixed and reacted at a temperature of 30 ° C. for 3 hours. Thereafter, the mixture was neutralized with hydrochloric acid and extracted with a mixed solvent of ethyl acetate / n-butanol = 1/1 (mass ratio) to obtain a resol type phenol resin solution.

(Measurement of thermal sensitivity)
4.0 parts of the thermoresponsive microcapsule liquid (a), 9.7 parts of the coupler compound emulsion dispersion, and 3.6 parts of water were uniformly mixed to prepare a thermal recording coating material. This paint was applied on a WP support having a thickness of 198 μm so that the solid coating amount of the diazonium salt compound (A) was 0.3 g / m ² . Similarly, the coating amount prepared using the thermoresponsive microcapsule liquids (b), (c), and (d) on a 198 μm-thick WP support has a solid coating amount of the diazonium salt compound of 0. It apply | coated so that it might become 3 g / m < ² >.
From the coated surface of these coated materials, heat printing was performed at an arbitrary temperature for 10 seconds using a 12-line automatic color development tester (Shinto Kagaku Co., Ltd.). The color development hue and color development start temperature are as follows.
Microcapsule (a): yellow, 76 ° C
Microcapsule (b) ......... Yellow, 85 ° C
Microcapsule (c): Magenta, 77 ° C
Microcapsule (d) ... Magenta, 85 ° C

(Preparation of thermal recording paint)
5.0 parts of the thermoresponsive microcapsule liquid (a), 5.0 parts of the thermoresponsive microcapsule liquid (d), 15.4 parts of the coupler compound emulsion dispersion, and the acrylic resin emulsion dispersion 8.2. Part, 0.3 part of the above-mentioned resol type phenol resin solution, and 1.2 parts of water were uniformly mixed to prepare a thermal recording type paint (1).

(Coating film creation and color evaluation)
The thermal recording paint (1) obtained above was applied onto a WP support having a thickness of 198 μm using a coating bar so as to have a dry film thickness of 30 μm and dried.
(1) When the coating film of this heat-recording type paint was heated with a heat roller at a temperature of 110 ° C. for 10 minutes, it developed a red color.
(2) The coating film of the heat-recording paint was heated with a heat roller at a temperature of 82 ° C. for 10 seconds, and then colored yellow.
(3) The coating film of the thermal recording paint was heated for 10 seconds at a temperature of 90 ° C. with a heat roller, and then colored orange.
As described above, it was confirmed that the coating film of the coating composition of the present invention can develop red, yellow and orange colors depending on the heating conditions.

[Example 2]
(Preparation of thermal recording paint)
In Example 1, instead of the thermoresponsive microcapsule liquid (a) used in (Preparation of thermal recording type paint), the thermoresponsive microcapsule liquid (b) was replaced with the thermoresponsive microcapsule liquid (d). Instead, a heat-recording paint (2) was prepared in the same manner as in Example 1 except that the responsive microcapsule liquid (c) was used.

(Coating film creation and color evaluation)
The thermal recording paint (2) obtained above was applied on a WP support having a thickness of 198 μm using a coating bar so that the dry film thickness was 30 μm.
(1) When the coating film of this heat-recording type paint was heated with a heat roller at a temperature of 110 ° C. for 10 minutes, it developed a red color.
(2) The coating film of the thermal recording type paint was exposed for 2 minutes with light having an emission center wavelength of 365 nm (irradiation energy: 4.00 mW / cm ² ) and then heated at 110 ° C. for 10 seconds with a heat roller. The color developed.
(3) The coating film of the heat-recording paint was heated with a heat roller at a temperature of 80 ° C. for 10 minutes, and then exposed with light having an emission center wavelength of 365 nm (irradiation energy: 4.00 mW / cm ² ) for 2 minutes. When the coating film was heated with a heat roller at a temperature of 110 ° C. for 10 minutes, it developed an orange color.
Similarly, it was confirmed that the coating film of the coating composition of the present invention can develop red, yellow, and orange colors due to differences in heating and exposure conditions.

Claims (9)

  At least a substantially colorless coloring component (a) and coloring component (b) capable of forming a dye by contacting and reacting with each other by application of external heat energy, one of which is a microcapsule A coating composition comprising: a coating composition comprising at least two or more kinds of microcapsules having different thermal sensitivities in the coating composition.   The coating composition according to claim 1, wherein the two or more kinds of microcapsules having different thermal sensitivities develop colors having different hues.   The coating composition according to claim 1 or 2, wherein the difference in thermal sensitivity between the two or more types of microcapsules is 3 ° C or more in a color development start temperature difference during static color development.   The coating composition according to any one of claims 1 to 3, wherein the wall material of the microcapsule is made of polyurethane and / or a polyurea polymer.   Furthermore, the coating composition in any one of Claims 1-4 containing the aqueous resin which has a hydroxyl group.   Furthermore, the coating composition in any one of Claims 1-5 containing a resol type phenol resin.   7. The color developing component (a) and the color developing component (b) are a photodegradable diazonium salt and a coupler compound, and the diazonium salt is encapsulated in a microcapsule. A coating composition according to claim 1.   Before the photo-decomposition of the diazonium salt encapsulated in the microcapsules with relatively high thermal sensitivity into the coating film coated with the coating composition according to claim 7, the microcapsules with relatively low thermal sensitivity are converted into microcapsules. A thermochromic recording method comprising forming two or more color-mixed images by applying thermal energy capable of thermocoloring by an encapsulated diazonium salt and a coupler.   The coating film coated with the coating composition according to claim 7 is provided with (1) thermal energy capable of thermal coloring with a diazonium salt and a coupler encapsulated in a microcapsule having the highest thermal sensitivity. After performing the first thermochromic recording for color development, (2) the diazonium salt is decomposed by exposure to light having a wavelength for decomposing the diazonium salt, and then (3) microcapsules having the second highest thermal sensitivity. A second thermal color recording is performed in which the encapsulated diazonium salt and the coupler are applied with thermal energy capable of thermal color development to develop a color, and (4) the wavelength at which the diazonium salt involved in the second color development is decomposed. A thermochromic recording method, wherein color development is recorded by repeating the procedure of color development and fixing in which the diazonium salt is decomposed by exposure to light in the descending order of thermal sensitivity.