JP2007090816A - Thermosensitive recording body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermosensitive recording body, which is superior in light-resistance and the discoloration of the ground part of which is little due to moisture resistance. <P>SOLUTION: In the thermosensitive recording body 1 consisting of a support 2, a color developing layer 3, which is provided on the support 2 and includes a colorless or light-colored leuco compound and a developer coloring the leuco compound under heat, a first intermediate layer 4, which is provided on the color developing layer 3 and includes a water soluble resin and an over coating layer 6, which is provided on the first intermediate layer 4 and is obtained by curing a layer including an ultraviolet curing resin through the irradiation with ultraviolet rays thereonto, a water soluble titanium compound is included as a curing agent in the first intermediate layer 4. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a heat-sensitive recording material, and more particularly to a heat-sensitive recording material that is excellent in light resistance and has little discoloration of the background due to moisture resistance.

  Conventionally, a heat-sensitive recording material that utilizes a color reaction between a color former and a color former that is brought into contact with the color former to obtain a color image by contacting both color developing substances by heat is well known. ing. Such a thermal recording medium is relatively inexpensive, and since the recording device is compact and relatively easy to maintain, it is used not only as a recording medium for facsimiles and various computing devices but also in a wide range of fields such as thermal labels. ing.

  However, depending on the product, the attached thermal recording paper is exposed to sunlight, or the recorded image is fading or the ground color part is likely to be discolored due to the influence of the storage environment.

As a method for eliminating such defects, a method of adding an antioxidant or an ultraviolet absorber to the heat-sensitive recording layer in order to improve the light resistance of the recorded image (see, for example, Patent Documents 1, 2, and 3). ) Has been proposed. However, at present, satisfactory results are not always obtained, for example, there is a problem with discoloration of the background.
JP-A 49-54040 Japanese Utility Model Publication No. 50-104650 JP 60-48395 A

  An object of the present invention is to solve the above-mentioned problems occurring in a heat-sensitive recording material provided with an overcoat layer of an ultraviolet curable resin, and to provide a heat-sensitive recording material that has excellent light resistance and little discoloration of the background due to moisture resistance. It is to be.

As a result of intensive research to solve the above problems, the present inventors have used a water-soluble titanium compound as a curing agent in the intermediate layer containing the water-soluble resin, and then applied ultraviolet rays to the layer containing the ultraviolet curable resin. It has been found that by providing an overcoat layer cured by irradiation, a heat-sensitive recording material having excellent light resistance and less discoloration of the background due to moisture resistance can be obtained, and the present invention has been completed.
Specifically, the heat-sensitive recording material according to claim 1 comprises a support, a color development layer provided on the support, and containing a colorless or light-colored leuco compound and a color developer that develops the leuco compound when heated. And a first intermediate layer containing a water-soluble resin provided on the color-developing layer, and an overcoat provided on the first intermediate layer and cured by irradiating the layer containing the ultraviolet curable resin with ultraviolet rays. In the heat-sensitive recording material provided with a layer, a water-soluble titanium compound is contained as a curing agent in the first intermediate layer.

The heat-sensitive recording material according to claim 2 is the heat-sensitive recording material according to claim 1, the coating amount of the coating liquid of the first intermediate layer is a 0.1g ^{/ m 2} ~10g ^/ m 2 by dry weight It is characterized by that.

  Furthermore, the heat-sensitive recording material according to claim 3 is the heat-sensitive recording material according to claim 1 or 2, wherein a polyvinyl alcohol-modified acrylate emulsion is contained between the first intermediate layer and the overcoat layer. A second intermediate layer is provided.

  The thermal recording medium according to claim 4 is the thermal recording medium according to any one of claims 1 to 3, wherein the leuco compound is a basic dye and the developer is an acidic substance. To do.

In the heat-sensitive recording material according to claim 1, the water-soluble titanium compound is contained as a curing agent in the first intermediate layer provided between the color-developing layer and the overcoat layer, thereby being excellent in light resistance and moisture resistance. Therefore, it is possible to realize a heat-sensitive recording material with less discoloration of the background portion.
Here, the leuco compound constituting the color developing layer of the heat-sensitive recording material is preferably colorless or pale.

In the heat-sensitive recording material according to claim 2, since the coating amount of the first intermediate layer is adjusted to 0.1 to 10 g / m ² by dry mass, it is further excellent in light resistance and moisture resistance. It is possible to reduce discoloration of the background due to.

  Furthermore, in the thermosensitive recording material according to claim 3, since the second intermediate layer containing the polyvinyl alcohol-modified acrylate emulsion is provided between the first intermediate layer and the overcoat layer, the chemical resistance is improved. In addition, it is possible to achieve excellent print running properties and interlayer adhesion.

  In the heat-sensitive recording material according to claim 4, since the leuco compound is a basic dye and the developer is an acidic substance, the recording characteristics can be improved.

Hereinafter, the thermosensitive recording material according to the present invention will be described based on embodiments embodying the present invention. The components used in the thermal recording material described below are merely examples, and the present invention is not limited to these.
First, the configuration of the thermal recording material according to the present embodiment will be outlined based on FIG. FIG. 1 is a schematic explanatory view schematically showing a heat-sensitive recording material.

In FIG. 1, a heat-sensitive recording material 1 basically includes a color developing layer 3 containing a leuco compound and a color developer that develops color when the leuco compound is heated on a support 2 in order from the bottom, water-soluble. A first intermediate layer 4 containing at least one of a resin and a water-dispersible resin, and an overcoat layer 6 that is cured by irradiating ultraviolet rays onto a layer containing an ultraviolet curable resin are provided.
In addition, as shown in FIG. 2, a second intermediate layer containing a polyvinyl alcohol (PVA) -modified acrylate emulsion produced by an emulsion polymerization method between the first intermediate layer 4 and the overcoat layer 6. 5 may be provided. FIG. 2 is a schematic cross-sectional view schematically showing another example of the thermal recording material.

  Here, as the support 2, high-quality paper, medium-quality paper, glossy paper, medium-coated paper, fine-coated paper, coated paper, art paper, cast-coated paper, clear-coated paper, resin-laminated paper, plastic film Synthetic paper, metal foil, etc., or a composite sheet combining these can also be used arbitrarily.

  Further, the combination of the color former and the developer contained in the color developing layer 3 is not particularly limited, and any combination that causes a color reaction when they are brought into contact with each other by heat can be used. Examples include a combination of a colorless and light leuco dye and an inorganic or organic acidic substance, a combination of a higher fatty acid metal salt such as ferric stearate and a phenol such as gallic acid, and the like.

  In particular, when a combination of a leuco dye and an acidic substance is used, the recording characteristics are extremely excellent, which is preferable. Various kinds of colorless or light leuco dyes are known, and examples thereof include the following.

3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) phthalide, 3- (p-dimethylindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide 3,3-bis (1,2-dimethylindol-3-yl) -5-dimethylaminophthalide, 3,3- Bis (1,2-dimethylindol-3-yl) -6-dimethylaminophthalide, 3,3-bis (9-ethylcarbazol-3-yl) -6-dimethylaminophthalide, 3,3-bis ( Triarylmethane series such as 2-phenylindol-3-yl) -6-dimethylaminophthalide and 3-p-dimethylaminophenyl-3- (1-methylpyrrol-3-yl) -6-dimethylaminophthalide Dyes, 4,4'-bis-dimethylaminobenzhydrylbenzyl ether, N-halophenyl-leucooramine, N-2,4,5-trichlorophenylleucooramine Diphenylmethane dyes, benzoyl leucomethylene blue, p-nitrobenzoyl leucomethylene blue, and other thiazine dyes, 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3-phenyl-spiro-dinaphthopyran, 3-methyl- Spiro dyes such as naphtho (6'-methoxybenzo) spirohypyran, 3-propyl-spiro-dibenzopyran, lactam dyes such as rhodamine-B anilinolactam, rhodamine (o-chloroanilino) lactam, 3-dimethylamino-7 -Methoxyfluorane, 3-dimethylamino-6-methoxyfluorane, 3-diethylamino-6-methoxyfluorane, 3-diethylamino-7-methoxyfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino- 6,7-dimethylfluorane, 3- (N-ethyl-p-toluidino) -7-methylfluorane, 3-diethyl Amino-7-N-acetyl-N-methylaminofluorane, 3-diethylamino-7-N-methylaminofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3-diethylamino-7-N-methyl- N-benzylaminofluorane, 3-diethylamino-7-N-chloroethyl-N-methylaminofluorane, 3-diethylamino-7-N-diethylaminofluorane, 3- (N-ethyl-7-p-toluidino)- 6-methyl-7-phenylaminofluorane, 3- (N-ethyl-p-toluidino) -6-methyl-7- (p-toluidino) fluorane, 3-dimethylamino-6-methyl-7-phenylaminofluorane Oran, 3-diethylamino-6-methyl-7-phenylaminofluorane, 3-diethylamino-7- (2-carbomethoxy-phenylamino) fluorane, 3- (N-cyclohexyl-N-methylamino) -6 -Methyl-7-phenylaminofluorane, 3-pyrrolidino-6-methyl-7-phenyl Minofluorane, 3-diethylamino-6-methyl-7-xylidinofluorane, 3-diethylamino-7- (o-chlorophenylamino) fluorane, 3-butylamino-7- (o-chlorophenylamino) fluorane, 3-pyrrolidino- 6-methyl-7-p-butylphenylaminofluorane, 3-diethylamino-7- (o-fluorophenylamino) fluorane, 3-dibutylamino-6-methyl-7-phenylaminofluorane, 3- (N- Methyl-Nn-amyl) amino-6-methyl-7-phenylaminofluorane, 3- (N-ethyl-Nn-amyl) amino-6-methyl-7-phenylaminofluorane, 3- (N-ethyl- N-iso-amyl) amino-6-methyl-7-phenylaminofluorane, 3- (N-methyl-Nn-hexyl) amino-6-methyl-7-phenylaminofluorane, 3- (N-ethyl- N-β-ethylanehexyl) amino-6-methyl-7-phenylaminofluorane, 3- [N- (3-ethoxypropyi )-N-ethyl] fluoran dyes such as amino-6-methyl-7-anilinofluoran and the like.
In addition, these basic dyes can use 2 or more types together as needed.
The dye precursor is appropriately selected and used depending on the application of the heat-sensitive recording material and desired properties.

  In addition, various inorganic or organic acidic substances that develop color upon contact with a basic colorless dye are known, for example, inorganic acidic substances such as activated clay, acid clay, attapulgite, bentonite, colloidal silica, and aluminum silicate. 2-4'-dihydroxydiphenylsulfone, 4,4'-dihydroxydiphenylsulfone, 4-hydroxy-4'-isopropyloxydiphenylsulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, 4-hydroxy-4'- Hydroxyphenylsulfone derivatives such as methyl-diphenylsulfone, 3,4-dihydroxydiphenylsulfone, 3,4-dihydroxy-4'-methyldiphenylsulfone, 4-tert-butylphenol, 4-hydroxydiphenoxide, α-naphthol, β- Naphthol, 4-hydroxyacetophenol, 4-tert-octylcatechol, 2,2'-dihydroxydiphenol, 4,4'-isopropylidenebus (2-tert-butylphenol), 4,4'-sec-butylidenediphenol 4-phenylphenol, 4,4'-isopropylidene diphenol, 4,4'-dihydroxydiphenylmethane, 2,2'-bis (4- Hydroxy) -4-methylpentane, 2,2'-methylenebis (4-chlorophenol), hydroquinone, 4,4'-cyclohexylidene diphenol, 4,4'-dihydroxydiphenyl sulfide, hydroquinone monobenzyl ether, 4-hydroxy Benzophenone, 2,4-dihydroxybenzophenone, 2,4,4'-trihydroxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone, dimethyl 4-hydroxyphthalate, methyl 4-hydroxybenzoate, 4- Propyl hydroxybenzoate, 4-hydroxybenzoate-sec-butyl, pentyl 4-hydroxybenzoate, phenyl 4-hydroxybenzoate, benzyl 4-hydroxybenzoate, tolyl 4-hydroxybenzoate, chlorophenyl 4-hydroxybenzoate, 4-hydroxybenzoate phenylpropyl, 4-hydroxybenzoate phenethyl 4-hydroxybenzoic acid-p-methoxybenzyl, novolak-type phenolic resin, phenolic compounds such as phenolic polymer, terephthalaldehyde acid, benzoic acid, p-tert-butylbenzoic acid, trichlorobenzoic acid, terephthalic acid, 3-sec -Butyl-4-hydroxybenzoic acid, 3-cyclohexyl-4-hydroxybenzoic acid, 3,5-dimethyl-4-hydroxybenzoic acid, 3-tert-butylsalicylic acid, 3-benzylsalicylic acid, 3- (α-methylbenzyl ) Salicylic acid, 3-chloro-5- (α-methylbenzyl) salicylic acid, 3,5-di-tert-butylsalicylic acid, 3-phenyl-5- (α, αdimethylbenzyl) salicylic acid, 3,5-di-α Aromatic carboxylic acids such as 2-methylbenzylsalicylic acid, 4- [3- (p-tolylsulfonyl) propyloxy] salicylic acid, bis (3-tert-butyl-4-hydroxy-6-methylphenyl) sulfide, bis (2- Methyl-4-hydroxy-6 -tert-butylphenyl) sulfide, sulfide derivatives such as bis (4-hydroxy-3-methylphenyl) sulfide, and these phenolic compounds, aromatic carboxylic acids and the like, for example, zinc, magnesium, aluminum, calcium, titanium And salts with polyvalent metals such as manganese, tin, and nickel, and further antipyrine complexes of zinc thiocyanate and organic acidic substances such as 4,4-bis (p-tolylsulfonylurea) diphenylmethane.

  The use ratio of the basic dye and the developer is appropriately adjusted according to the type of the basic dye and the colorant to be used, but generally 50 to 500 parts by weight, preferably 100 parts by weight of the basic dye. A colorant of about 100 to 300 parts by weight is used. The heat-sensitive recording layer coating liquid containing these substances is generally prepared by using water as a dispersion medium and dispersing with a stirring / pulverizing machine such as a ball mill or a sand mill.

  In the color developing layer coating solution, binders of about 10 to 40% by weight, more preferably about 15 to 30% by weight of the total solid content are blended. Specific examples of binders include, for example, starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, PVA, acetoacetyl-modified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, diisobutylene. , Maleic anhydride copolymer salt, styrene / maleic anhydride copolymer salt, ethylene / acrylic acid copolymer salt, styrene / acrylic acid copolymer salt, styrene / butadiene copolymer emulsion, urea resin, melamine resin And amide resins.

  Furthermore, for the purpose of improving the storability of the recorded image, a storability improving agent can be added. Specific examples of such preservability improvers include, for example, 1,4-diglycidyloxybenzene, 4,4′-diglycidyloxydiphenylsulfone, diglycidyl terephthalate, 4-benzyloxy-4 ′-(2-methyl-2 , 3-epoxypropyloxy) diphenylsulfone, 2,2'-dithiodibenzoic acid, 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 2,2'-ethylidenebis (4,6-di-) -tert-butylphenol), 4,4'-thiobis (3-methyl-6-tert-butylphenol), 4,4'-thiobis (2-methyl-6-tert-butylphenol), 4,4'-butylidenebis (6 -tert-butyl-m-cresol), 2,5-di (tert-butyl) hydroquinone, 2,5-di (tert-amyl) hydroquinone, 1,1,3-tris (2-methyl-4-hydroxy- 5-cyclohexylphenyl) butane, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenol) butane, 4,4'-dihydroxy-3,3 ', 5,5'-te Labromodiphenylsulfone, 4,4'-dihydroxy-3,3 ', 5,5'-tetramethyldiphenylsulfone, 2,2'-bis (4-hydroxy-3,5-dipromophenyl) propane, 2, Hindered phenol compounds such as 2-bis (4-hydroxy-3,5-dichlorophenyl) propane and 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, 1- [α-methyl-α- (4'-hydroxyphenyl) ethyl] -4- [α ', α'-bis (4 "-hydroxyphenyl) ethyl] benzene, N, N'-di-2-naphthyl-p-phenylenediamine, 2,2 -Methylenebis (4,6-di-tert-butylphenyl) phosphate, copolymer of glycidyl methacrylate and styrene, and tris (2,3-epoxypropyl) isocyanate.

  Further, various auxiliary agents can be added to the color forming layer coating liquid as necessary, for example, sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, lauryl alcohol sulfate / sodium salt, fatty acid metal salt, etc. In addition to the above-mentioned dispersant and the above-mentioned specific ultraviolet absorber, benzophenone-based ultraviolet absorbers, antifoaming agents, fluorescent dyes, colored dyes and the like are appropriately added. Furthermore, if necessary, waxes such as zinc stearate, calcium stearate, polyethylene wax, carba wax, paraffin wax, ester wax, carnauba wax, paraffin wax, ester wax, kaolin, clay, calcined clay, talc, calcium carbonate, calcined It is possible to add inorganic pigments such as kaolin, titanium oxide, diatomaceous earth, fine particulate anhydrous silica, and activated clay, and a sensitizer can be used in combination according to the purpose.

  Specific examples of the sensitizer include, for example, stearic acid amide, stearic acid methylene bisamide, oleic acid amide, valmitic acid amide, coconut fatty acid amide and other fatty acid amides, 2,2′-methylene bis (4-methyl-6-tert -Butylphenol), 4,4'-butylidenebis (6-tert-butyl-3-methylphenol), 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 2,4'-di-tert- Hindered phenols such as butyl-3-methylphenol, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2-hydroxy-4-benzylbiphenyl, 1,2-di (3-methylphenoxy) Ethane, 1,2-diphenoxyethane, 1- (2-methylphenoxy) -2- (4-methoxyphenoxy) ethane, naphthyl benzyl ether, benzyl-4-methylthiophenyl ether, oxalic acid dibenzyl ester, oxalic acid- Di-p-methyl-ben Ester, oxalic acid-di-p-chlorobenzyl ester, terephthalic acid dimethyl ester, terephthalic acid dibutyl ester, terephthalic acid dibenzyl ester, isophthalic acid dibutyl ester, 1-hydroxynaphthoic acid phenyl ester, benzyl-4-methylthiophenyl ether , O-chloroacetoacetaniline and various known heat-fusible substances.

  In addition, these sensitizers can use 2 or more types together as needed. In general, the amount of the sensitizer used is preferably adjusted within a range of about 400 parts by weight or less with respect to 100 parts by weight of the colorant.

The method for forming the color developing layer 3 is not particularly limited. For example, the heat-sensitive recording layer forming coating solution is applied to a support and dried by an appropriate application method such as air knife coating, rod coating, blade coating, short dwell coating, or the like. Formed by the method. The coating amount of the coating liquid is not particularly limited, usually 2~14g / ^{m 2} in dry weight, preferably is preferably in the range of 5 to 10 g / ^{m 2.}

  In the heat-sensitive recording material 1 according to the present embodiment, the first intermediate layer 4 mainly composed of a water-soluble resin and containing a water-soluble titanium compound as a curing agent is formed on the color developing layer 3 obtained as described above. However, the water-soluble resin used for the first intermediate layer 4 is exemplified by the following substances.

Fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, acetoacetylated polyvinyl alcohol, reaction product of polyhydric carboxylic acid such as fumaric acid, phthalic anhydride, trimellitic anhydride, itaconic anhydride, or these reactions Carboxy-modified polyvinyl alcohol and vinyl acetate obtained as saponification products of vinyl acetate and copolymers of ethylenically unsaturated carboxylic acids such as maleic acid, phthalic acid, itaconic acid, crotonic acid and acrylic acid Sulfonic acid-modified polyvinyl alcohol, vinyl acetate and ethylene, propylene, isobutylene, α-octene, α-dodecene, obtained as a saponified product of a copolymer of olefin sulfonic acid such as ethylene sulfonic acid, acrylic sulfonic acid or its salt α-o Olefin-modified polyvinyl alcohol obtained by saponifying a copolymer with an olefin such as tadodecene, nitrile-modified polyvinyl alcohol obtained as a saponified product of a copolymer of vinyl acetate with nitriles such as acrylonitrile and methacrylonitrile, acetic acid Pyrrolidone-modified polyvinyl alcohol obtained by saponifying a copolymer of vinyl and N-vinylpyrrolidone, cellulose derivatives such as methylcellulose, ethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, casein, gum arabic, oxidized starch, etherified starch, dialdehyde starch And starches such as esterified starch.
Among these water-soluble resins, various modified polyvinyl alcohols, cellulose derivatives and casein are preferable, and acetoacetylated polyvinyl alcohol and carboxy-modified polyvinyl alcohol are particularly preferable. The amount of the water-soluble resin or water-dispersible resin used is not particularly limited, but is 10 to 50% by weight, preferably about 15 to 40% by weight, based on the total solid content in the coating liquid.

  A pigment can be added to the first intermediate layer 4 as necessary. Specific examples of pigments include calcium carbonate, zinc oxide, aluminum oxide, titanium dioxide, silicon dioxide, aluminum hydroxide, barium sulfate, zinc sulfate, talc, kaolin, clay, calcined clay, colloidal silica and other inorganic pigments, styrene micro Examples thereof include organic pigments such as balls, nylon powder, polyethylene powder, urea / formalin resin filler, and raw starch granules. The amount used is generally 5 to 500 parts by weight, preferably about 80 to 350 parts by weight per 100 parts by weight of the resin component.

  Further, in the coating liquid forming the first intermediate layer 4, glyoxal, methylol melamine, potassium persulfate, ammonium persulfate, sodium persulfate, ferric chloride, magnesium chloride, boric acid, ammonium chloride, etc. A curing agent may be used in combination, and if necessary, lubricants such as zinc stearate, calcium stearate, stearamide, polyethylene wax, carnauba wax, paraffin wax, ester wax, sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, Add surfactants such as lauryl alcohol sulfate / sodium salt, alginate, fatty acid metal salt, etc., UV absorbers such as benzophenone and triazole, antifoaming agents, fluorescent dyes, coloring dyes, etc. You can also.

The coating liquid for forming the first intermediate layer 4 is generally prepared as an aqueous coating liquid, and after being sufficiently mixed and dispersed by a mixer / agitator such as a mixer, attritor, ball mill, roll mill, etc. The heat-sensitive recording layer is coated by a known coating device. When a curing agent is used in combination, the curing agent can be applied not only in the coating liquid for forming the first intermediate layer 4 but also separately from the coating liquid for forming the first intermediate layer 4. In this case, there is no need to worry about the pot life of the coating liquid, and there is an advantage that a strong curing agent can be selected.
Further, if necessary, it is possible to further improve the storage stability by providing a similar coating layer on the back surface of the thermal recording medium 1. Furthermore, various known techniques in the manufacturing field of the thermal recording body 1 are added as necessary, such as providing an undercoat layer on the support 2, applying an adhesive treatment to the back surface of the thermal recording body 1, and processing it into an adhesive label. To get.
The coating amount of the coating liquid for forming the first intermediate layer 4 is not particularly limited, but if it is less than 0.1 g / m ² , the desired effect of the present invention cannot be sufficiently obtained, and 20 g / ^{m 2} to Kosu When because it may decrease significantly the recording sensitivity of the heat sensitive recording material, generally 0.1 g ^/ m 2 by dry weight to to 20 g / ^{m 2,} preferably 0.5 g ^/ m 2 to 10 g / m It is adjusted within a range of about ² .

  As shown in FIG. 2, on the first intermediate layer 4 obtained as described above, the second intermediate layer is used as a layer for bonding the ultraviolet curable resin between the first intermediate layer 4 and the ultraviolet curable resin. When the layer 5 is formed, the second intermediate layer 5 is provided with a layer containing a PVA (polyvinyl alcohol) -modified acrylate emulsion obtained by an emulsion polymerization method. In the intermediate layer 5, a pigment can be added to increase the smoothness. Specific examples of pigments include calcium carbonate, zinc oxide, aluminum oxide, titanium dioxide, silicon dioxide, aluminum hydroxide, barium sulfate, zinc sulfate, talc, kaolin, clay, calcined clay, colloidal silica and other inorganic pigments, styrene micro Examples thereof include organic pigments such as balls, nylon powder, polyethylene powder, urea / formalin resin filler, and raw starch granules. The amount used is generally 5 to 500 parts by weight, preferably about 80 to 350 parts by weight per 100 parts by weight of the resin component.

  Furthermore, in the coating liquid forming the second intermediate layer 5, glyoxal, methylol melamine, potassium persulfate, ammonium persulfate, sodium persulfate, ferric chloride, magnesium chloride, boric acid, ammonium chloride, etc. Hardeners may be added, if necessary, lubricants such as zinc stearate, calcium stearate, stearamide, polyethylene wax, carnauba wax, paraffin wax, ester wax, sodium dioctyl sulfosuccinate, sodium dodecylbenzene sulfonate, lauryl Various additives such as surfactants such as alcohol sulfates / sodium salts, alginates, fatty acid metal salts, UV absorbers such as benzophenone and triazole, antifoaming agents, fluorescent dyes, and coloring dyes may be added as appropriate. it can.

The coating solution for forming the second intermediate layer 5 is generally prepared as an aqueous coating solution, and after being sufficiently mixed and dispersed by a mixer / agitator such as a mixer, attritor, ball mill, roll mill, etc. The heat-sensitive recording layer is coated by a known coating device. When a curing agent is used in combination, the curing agent can be applied not only in the coating liquid for forming the second intermediate layer 5 but also separately from the coating liquid for forming the second intermediate layer 5. Then, there is no need to worry about the pot life of the coating liquid, and there is an advantage that a strong curing agent can be selected.
The coating amount of the coating liquid for forming the second intermediate layer 5 is not particularly limited, but if it is less than 0.1 g / m ² , the desired effect of the present invention cannot be obtained sufficiently, and If it exceeds 10 g / m ² , the recording sensitivity of the thermosensitive recording medium may be remarkably lowered. Therefore, the dry weight is generally 0.1 g / m ^{2 to} 10 g / m ² , preferably 0.5 g / m ^{2 to} 5 g. / M ² is adjusted in the range.

On the first intermediate layer 4 (see FIG. 1) or the second intermediate layer 5 (see FIG. 2) obtained as described above, an overcoat layer 6 cured by irradiating ultraviolet rays onto a layer containing an ultraviolet curable resin. Is provided. The ultraviolet curable resin used for the overcoat layer 6 is not limited to that type, and various conventionally known ones can be used.
Here, the ultraviolet curable resin used for forming the overcoat layer 6 can be any prepolymer or monomer that undergoes a polymerization reaction upon irradiation with ultraviolet rays and is cured to form a resin. Such prepolymers and monomers are listed below, but are not particularly limited thereto. Prepolymers include epoxy (meth) acrylate, urethane (meth) acrylate, saturated polyester / styrene, polyethylene (meth) acrylate, polyether (meth) acrylate, silicon (meth) acrylate, polybutadiene (meth) acrylate, polyethylene / thiol , Polystyrylethyl (meth) acrylate, polyamide (meth) acrylate, and the like. As monomers, styrene, vinyl acetate, vinyl monomers such as N-vinylpyrrolidone, butyl acrylate, 2-ethylhexyl acrylate, n-hexyl acrylate, cyclohexyl acrylate, n-decyl acrylate isobornyl acrylate, dicyclopentenyloxyethyl acrylate, Monofunctional monomers such as phenoxyethyl acrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, diethylene glycol diacrylate, neopentyl glycol diacrylate, polyethylene glycol 400 diacrylate, tripropylene glycol diacrylate, bisphenol A diethoxydiacrylate, tetraethylene glycol diacrylate, hydroxypivalic acid neo Emissions chill glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, polyfunctional monomers such as dipentaerythritol hexaacrylate.

  Further, examples of photoinitiators that are usually required when using an ultraviolet curable resin include acetophenone, benzophenone, benzoin ether, chloroacetophenone, diethoxyacetophenone, hydroxyacetophenone, α-aminoacetophenone, benzylmethyl ketal, thioxanthone, α -Alsioxime ester, acyl phosphine oxide, glyoxy ester, 3-ketocoumarin, 2-ethylanthraquinone, camphorquinone, benzyl, Michler's ketone and the like.

In addition to the prepolymers and monomers of the ultraviolet curable resin as described above, the photoinitiator, in the resin component, for example, a non-ultraviolet curable resin, an antifoaming agent, a leveling agent, etc. Additives such as a lubricant, a surfactant, an ultraviolet absorber, a fluorescent dye, a colored dye, a pigment, a fluorescent pigment, and a colored pigment can be appropriately added.
Examples of the non-ultraviolet curable resin include acrylic resin, silicon resin, alkyd resin, fluororesin, butyral resin, and the like.
The resin component as described above is sufficiently stirred by a suitable mixing stirrer such as a mixer and then applied on the second intermediate layer 5 by various known methods. As a method of forming the overcoat layer 6, Then, the obtained emulsion is applied onto the second intermediate layer 5 by a gravure coater, a screen printing machine, a flexographic printing machine or the like by a method known per se to evaporate water. The coating amount is not particularly limited, but the object of the present invention cannot be achieved at a dry weight of 0.2 g / m ² or less, and at a dry weight of 20 g / m ² or more, the recording density of the thermosensitive layer is low. because may decrease the unfavorable generally dry weight ^{0.2g / m 2 ~20g / m 2} , it is preferably adjusted in the range of about ^{0.5g / m 2 ~10g / m 2} .

  EXAMPLES The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to these examples. Unless otherwise specified, “parts” and “%” in the examples represent “parts by weight” and “% by weight”, respectively.

Example 1
(Configuration of heat sensitive liquid)
(Preparation of liquid A)
Dibutylamino-6-methyl-7-anilinofluorane 30 parts by weight Polyvinyl alcohol 10% aqueous solution 50 parts by weight Water 20 parts by weight This composition was pulverized with a sand mill and pulverized until the average particle size was 0.5 μm or less. .

(Preparation of B liquid)
Bis (3-allyl-4-hydroxyphenyl) sulfone 25 parts by weight Polyvinyl alcohol 10% aqueous solution 40 parts by weight Water 35 parts by weight This composition was pulverized with a sand mill until the average particle size was 1 μm or less.

(Preparation of liquid C)
Oxalic acid-di-p-methylbenzyl ester 30 parts by weight Polyvinyl alcohol 10% aqueous solution 30 parts by weight Water 40 parts by weight This composition was pulverized with a sand mill and pulverized until the average particle size became 1 μm or less.

(Formation of coloring layer)
Water 100 parts by weight Liquid A 110 parts by weight Liquid B 200 parts by weight Liquid C 220 parts by weight Polyvinyl alcohol 20% aqueous solution 80 parts by weight Calcium carbonate 40% dispersion 40 parts by weight Zinc stearate 30% dispersion 20 parts by weight Mixing and stirring were performed to obtain a coating solution for a color developing layer. The resulting coating solution was applied and dried on a 38 μm thick polyester film using a wire bar so that the dry weight was 9 g / m ² , thereby obtaining the color developing layer 3.

(Formation of first intermediate layer)
On the color developing layer 3 obtained as described above, a coating solution having the following composition was applied and dried so that the dry weight was 2 g / m ² , thereby forming the first intermediate layer 4.
Modified polyvinyl alcohol 10% aqueous solution [trade name: RS-2117, manufactured by Kuraray Co., Ltd.] 1000 parts by weight Water-soluble titanium compound (trade name: ORGATICS TC-310) 50 parts by weight Water 150 parts by weight

(Formation of overcoat layer)
On the first intermediate layer 4 obtained as described above, a coating liquid having the following composition was applied so as to have a dry weight of 4 g / m ^2, and after evaporating water, a high-pressure mercury lamp of 80 W / cm was provided. The thermosensitive recording material 1 according to the present embodiment is formed by curing the resin component by irradiating ultraviolet rays twice with a UV irradiation device (ASE-20: manufactured by Nihon Battery Co., Ltd.) at a conveyance speed of 40 m / min to form an overcoat layer 6. Obtained.
UV curable resin composition (trade name: KAYANOVA FOP-3500) 60 parts by weight Toluene 40 parts by weight

(Example 2)
(Formation of second intermediate layer)
On the first intermediate layer 4 obtained in the same manner as in Example 1, a coating liquid having the following composition was applied and dried so that the dry weight was 1.5 g / m ² to form the second intermediate layer 5, Further, an overcoat layer 6 was formed on the second intermediate layer 5 in the same manner as in Example 1 to obtain a thermal recording material 1.
PVA-modified acrylic ester emulsion obtained by emulsion polymerization method [trade name: VA-901, manufactured by Nissin Chemical Co., Ltd.] (28.6% solution) 100 parts by weight Glyoxal (40.0%) 10 parts by weight Stearin Zinc acid 30% dispersion 20 parts by weight Water 86 parts by weight

(Comparative Example 1)
In the adjustment of the first intermediate layer 4, the thermosensitive recording material 1 was obtained in the same manner as in Example 1 except that the first intermediate layer 4 was adjusted without using a water-soluble titanium compound.

(Comparative Example 2)
A thermal recording medium 1 was obtained in the same manner as in Example 1 except that the first intermediate layer 4 was prepared using glyoxal instead of the water-soluble titanium compound in the adjustment of the first intermediate layer 4.

(Comparative Example 3)
A thermosensitive recording material 1 was obtained in the same manner as in Example 1 except that the first intermediate layer 4 was prepared using polyamide epichlorohydrin instead of the water-soluble titanium compound in the adjustment of the first intermediate layer 4.

quality evaluation:
The five types of thermal recording materials thus obtained were subjected to the following quality evaluation. The evaluation results are shown in Table 1.

  Printing: The above thermal recording material is cut to a width of 12 mm and incorporated in a special cassette for refill tape for a label writer (P-touch manufactured by Brother Industries, Ltd.) and a label writer P-touch 65 (manufactured by Brother Industries, Ltd.) is used. Characters and designs were printed.

Light resistance: Light source xenon, weatherometer set to 320 nm, 0.5 W / m ² , 40 ° C., 50% RH (manufactured by ATLAS ELECTRIC DEVICES COMPANY), stored for 100 hours under the conditions of Atlas Ci4000 xenon weatherometer Then, the recorded part and the ground color after storage were judged.
Recording section evaluation ○: There is almost no fading of printed characters and designs.
X: Fading of printed characters and designs was observed.
Evaluation of background portion ○: Almost no discoloration of the background color portion.
X: The discoloration of the ground color part was recognized.

Humidity resistance: Stored under high humidity conditions of 50 ° C. and 90% RH for 100 hours, and the recorded area and background color after storage were judged.
○: There is almost no fading of printed characters and designs.
X: Fading of printed characters and designs was observed.
Evaluation of background portion ○: Almost no discoloration of the background color portion.
X: The discoloration of the ground color part was recognized.

  As is apparent from Table 1, the heat-sensitive recording material obtained by the present invention is excellent in the storage stability of the recording area and the storage area of the background due to light resistance and moisture resistance.

  As described above in detail and specifically, according to the heat-sensitive recording material 1 according to the present embodiment, by using a water-soluble titanium compound as a curing agent in the first intermediate layer 4, the light resistance and moisture resistance can be increased. A heat-sensitive recording material excellent in the storage stability of the recording portion and the storage stability of the background portion can be obtained.

It is a schematic cross section which shows typically the thermosensitive recording material which concerns on this embodiment. It is a schematic cross section which shows typically another example of the thermosensitive recording material which concerns on this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thermal recording body 2 Support body 3 Color development layer 4 1st intermediate | middle layer 5 2nd intermediate | middle layer 1 Overcoat layer

Claims (4)

A support;
A color-forming layer provided on the support and containing a colorless or light-colored leuco compound and a developer that causes the leuco compound to develop a color when heated;
A first intermediate layer provided on the color-developing layer and containing a water-soluble resin;
In the thermosensitive recording medium provided with the overcoat layer provided on the first intermediate layer and cured by irradiating the layer containing the ultraviolet curable resin with ultraviolet rays,
A heat-sensitive recording material comprising a water-soluble titanium compound as a curing agent in the first intermediate layer. The coating amount of the coating liquid of the first intermediate layer, the heat-sensitive recording material according to claim 1, characterized in that a dry weight is ^{0.1g / m 2 ~10g / m 2} . 3. The heat-sensitive recording material according to claim 1, wherein a second intermediate layer containing a polyvinyl alcohol-modified acrylate emulsion is provided between the first intermediate layer and the overcoat layer. . 4. The heat-sensitive recording material according to claim 1, wherein the leuco compound is a basic dye, and the developer is an acidic substance.

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