JP2015150764A - Thermosensitive recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermosensitive recording medium having high recording sensitivity, excellent image stability, satisfactory ground fogging under high temperature storage, and no coloring failure after storage with time due to an influence by an adhesive component.SOLUTION: There is provided a thermosensitive recording medium having a primer coating layer containing a pigment and a binder on a supporter and a thermosensitive recording layer containing a leuco dye and a coloring agent on the primer coating. The thermosensitive recording medium contains at least one kind selected from an anionic styrene-acrylic copolymer resin and a styrene-maleic acid copolymer resin in the primer coating layer as a sizing agent and contains N-[2-(3-phenyl ureide)phenyl]benzensulfonamide as the coloring agent. It is preferable that 0.1 to 1.0 pts.mass of the sizing agent is contained with respect to 1 pts.mass of N-[2-(3-phenyl ureide)phenyl]benzensulfonamide.

Description

  The present invention relates to a heat-sensitive recording material utilizing a color development reaction between a leuco dye and a colorant.

  A thermal recording material using a color reaction between a leuco dye and a colorant is relatively inexpensive, and the recording device is compact and relatively easy to maintain. It is used not only as a recording medium but also in a wide range of fields. With the expansion of the field of use and the diversification and high performance of recording equipment, the usage environment and storage environment of recording media are becoming harsh, and high recording sensitivity and image stability are required. There is a particular demand for a heat-sensitive recording material for label use in which an adhesive layer and release paper are laminated on the back surface, so that the sensitivity does not decrease due to long-term storage after processing. Emulsion types such as rubber and acrylic types, solvent types, hot melt types, etc. are used as the pressure-sensitive adhesive that constitutes the pressure-sensitive adhesive layer of heat-sensitive recording labels. Acrylic emulsion types are used in terms of safety, quality, and cost. Adhesives are widely used. The low molecular weight oligomers, surfactants, etc. contained in these pressure-sensitive adhesive layers migrate to the heat-sensitive recording layer to reduce the recording sensitivity, causing problems such as defective reading of barcodes due to white spots in printing. It has been known.

  For the purpose of suppressing the influence of the pressure-sensitive adhesive component, the transmittance at 280 nm of a 0.01% by weight aqueous solution having a glass transition point of 10 ° C. or less is formed on the support surface opposite to the surface on which the thermosensitive recording layer is provided. Thermosensitive recording label provided with a backcoat layer containing a styrene-acrylic resin that is 2.0% or less (see Patent Document 1), mainly a thermoplastic resin between the backcoat layer on the back of the support and the adhesive layer There has also been proposed a thermosensitive recording adhesive label provided with an adhesive undercoat layer containing the filler described above (see Patent Document 2). It has also been proposed to use urea urethane compounds such as 4,4'-bis [(4-methyl-3-phenoxycarbonylaminophenyl) ureido] diphenylsulfone as a colorant (see Patent Document 3). However, these are also not sufficient for the effect of suppressing poor coloration due to the pressure-sensitive adhesive component, or there is a problem that the production process is complicated and the production efficiency is lowered to obtain a sufficient effect.

JP 2009-255309 A JP 2009-190263 A JP 2001-246859 A

  The main object of the present invention is to provide a heat-sensitive recording material having high recording sensitivity, excellent image stability, excellent background fogging under high-temperature storage, and no color development after storage over time due to the effect of the pressure-sensitive adhesive component. Objective.

  As a result of intensive studies in view of the above-described conventional technology, the present inventors have solved the above problems. That is, the present invention relates to the following thermal recording material.

  Item 1: In a heat-sensitive recording material comprising an undercoat layer containing a pigment and a binder on a support and a heat-sensitive recording layer containing a leuco dye and a colorant on the undercoat layer, an anionic styrene-acrylic copolymer as a sizing agent It contains at least one selected from a polymerization resin and a styrene-maleic acid copolymer resin in an undercoat layer, and contains N- [2- (3-phenylureido) phenyl] benzenesulfonamide as the colorant. A thermal recording medium.

  Item 2: The item according to item 1, wherein the sizing agent is contained in an amount of 0.1 to 1.0 part by mass with respect to 1 part by mass of the N- [2- (3-phenylureido) phenyl] benzenesulfonamide. Thermal recording material.

  Item 3: The heat-sensitive recording material according to item 1 or 2, wherein the pressure-sensitive adhesive layer is provided on the surface of the support opposite to the surface provided with the heat-sensitive recording layer or on the surface provided with the heat-sensitive recording layer.

  Item 4: The heat-sensitive recording material according to any one of Items 1 to 3, wherein the sizing agent is contained in a proportion of 1 to 20% by mass in the total solid content of the undercoat layer.

  Item 5: The heat-sensitive recording material according to any one of Items 1 to 4, further comprising a urea urethane compound represented by the following general formula (1) as the color former.

  Item 6: The urea urethane compound represented by the general formula (1) is 0.03 to 2.5 mass with respect to 1 mass part of the N- [2- (3-phenylureido) phenyl] benzenesulfonamide. Item 6. The heat-sensitive recording material according to Item 5, contained in parts.

  Item 7: The heat-sensitive recording material according to Item 5 or 6, wherein the urea urethane compound represented by the general formula (1) is heat-treated in the same liquid as the basic inorganic pigment.

  Item 8: The heat-sensitive recording material according to Item 7, wherein the basic inorganic pigment is at least one selected from the group consisting of a magnesium compound, an aluminum compound, a calcium compound, a titanium compound, magnesium silicate, magnesium phosphate and talc. .

  Item 9: The heat-sensitive recording material according to any one of Items 1 to 8, wherein the undercoat layer contains plastic hollow particles.

  Item 10: The heat-sensitive recording material according to any one of Items 1 to 9, further comprising an undercoat layer formed by a blade coating method between the support and the heat-sensitive recording layer.

  Item 11: The thermal recording material according to any one of Items 1 to 10, wherein at least one layer formed on the support is formed by a curtain coating method.

  The heat-sensitive recording material of the present invention has high recording sensitivity, excellent image stability, good background fogging at high temperature storage, and no color defect after storage over time due to the influence of the pressure-sensitive adhesive component.

  The present invention provides a heat-sensitive recording material provided with a heat-sensitive recording layer containing at least a leuco dye and a colorant on the support, and the layer structure of the heat-sensitive recording material includes the support and the heat-sensitive recording layer. The configuration is not limited to the above, but a configuration having an undercoat layer between the support and the thermal recording layer, and a configuration having an adhesive layer, a release paper, etc. on the side opposite to the side having the thermal recording layer of the support In addition, a configuration including a protective layer on the thermosensitive recording layer can be included.

  Although it does not specifically limit as a support body in this invention, For example, neutral or acidic quality paper (neutral paper, acidic paper), a synthetic paper, a transparent or translucent plastic film, a white plastic film etc. are mentioned. . Although the thickness of a support body is not specifically limited, Usually, it is about 20-200 micrometers.

  The support in the present invention is more preferably a neutral paper or acidic paper paper support obtained by making a pulp slurry containing pulp fibers, a filler and a sizing agent. In general, in the case of acidic paper, there is a problem that the color forming material constituting the heat-sensitive recording material reacts with acidic ions on the surface of the paper and easily causes background fogging during a long-term storage period. On the other hand, in the case of neutral paper, while the thermal recording medium is being stored, for example, less than one year, the coloring ability decreases before recording, and after recording, fading occurs and printing occurs. There are problems such as fading, blurring, and in some cases, it is almost invisible. Conventionally, the components to be included in the heat-sensitive recording layer have been properly used depending on the type of paper support, but in the present invention, both neutral paper and acid paper exhibit excellent effects on plasticizer resistance after storage of white paper. In addition, it is possible to obtain a heat-sensitive recording material excellent in storage stability of a blank paper having a latently high recording density while having heat resistance on the background. Although the reason for this is not clear, the performance of the colorant is reduced by forming a salt with the alkali filler contained in the neutral paper while the thermal recording material is stored. On the other hand, it is estimated that N- [2- (3-phenylureido) phenyl] benzenesulfonamide does not cause morphological changes regardless of whether it is neutral paper or acidic paper.

  The type of neutral paper and production method are not particularly limited, but pulp fibers and generally fillers such as calcium carbonate, sizing agents such as alkyl ketene dimer (AKD), alkenyl succinic anhydride (ASA), etc., and polyamides as fixing agents, A pulp slurry containing acrylic amide, cationic starch and the like can be obtained by paper making. As such neutral paper, the hot water extraction pH (based on JIS P 8133) is preferably in the range of 6.5 to 10, and more preferably in the range of 7.5 to 10. By setting the pH of the neutral paper to 6.5 or more, background fogging during storage of white paper can be effectively suppressed. On the other hand, aggregation of pulp slurry itself can be suppressed by setting pH to 10 or less. Moreover, as long as pH does not become smaller than 6.5, a pH can be adjusted using a sulfuric acid band as needed, and papermaking property can also be improved.

  Kinds of acid paper and production method are not particularly limited, but pulp fibers and fillers such as kaolin, talc, chlorite, rosin sizing agents such as reinforced rosin soap and reinforced rosin emulsion, alkenyl succinic acid soap, etc. A so-called synthetic sizing agent, etc., and a pulp slurry containing a sulfuric acid band and the like can be obtained by papermaking. Such acidic paper has a hot water extraction pH (based on JIS P 8133) in the range of about 2-6.

  Kinds of pulp fibers used in the present invention, production method and the like are not particularly limited. For example, various high-yield pulps in addition to chemical pulp and SCP such as softwood pulp and hardwood pulp obtained by KP, SP, AP method, and the like, Or a waste paper pulp etc. are mentioned.

  It should be noted that internal additives for papermaking such as dyes, fluorescent brighteners, pH adjusters, antifoaming agents, pitch control agents, slime control agents can be added to the pulp slurry as appropriate depending on the use of the paper. . Moreover, starch etc. can also be apply | coated in a size press. As the paper machine, a long net paper machine, a twin wire type paper machine, a circular net paper machine, a Yankee dryer paper machine and the like can be used as appropriate.

  The heat-sensitive recording layer in the present invention can contain various known leuco dyes of colorless or light color. Specific examples of such leuco dyes include, for example, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2-methylphenyl) -3- (4-dimethylamino) Phenyl) -6-dimethylaminophthalide, blue coloring dyes such as fluoran, 3- (N-ethyl-Np-tolyl) amino-7-N-methylanilinofluorane, 3-diethylamino-7-ani Green chromogenic dyes such as linofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3,6-bis (diethylamino) fluorane-γ-anilinolactam, 3-cyclohexylamino-6-chlorofluorane, 3 -Red coloring dyes such as diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-7-chlorofluorane, 3 (N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluorane, 3- (N-methyl-N-cyclohexyl) amino-6-methyl-7-anilinofluorane, 3-diethylamino- 6-methyl-7-anilinofluorane, 3-di (n-butyl) amino-6-methyl-7-anilinofluorane, 3-di (n-pentyl) amino-6-methyl-7-anilino Fluorane, 3-diethylamino-7- (o-chlorophenylamino) fluorane, 3- (N-ethyl-p-toluidino) -6-methyl-7-anilinofluorane, 3- (N-ethyl-p-toluidino) ) -6-methyl-7- (p-toluidino) fluorane, 3- (N-ethyl-N-tetrahydrofurfurylamino) -6-methyl-7-anilinofluorane, 3-diethylamino No-6-chloro-7-anilinofluorane, 3-dimethylamino-6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 3-piperidino-6 Methyl-7-anilinofluorane, 2,2-bis {4- [6 '-(N-cyclohexyl-N-methylamino) -3'-methylspiro [phthalide-3,9'-xanthen-2'-ylamino] ] Black} color developing dye such as phenyl} propane, 3-diethylamino-7- (3′-trifluoromethylphenyl) aminofluorane, 3,3-bis [1- (4-methoxyphenyl) -1- (4- Dimethylaminophenyl) ethylene-2-yl] -4,5,6,7-tetrachlorophthalide, 3,3-bis [1- (4-methoxyphenyl) -1- (4-pyrrolidinophenyl) e Len-2-yl] -4,5,6,7-tetrachlorophthalide, 3-p- (p-dimethylaminoanilino) anilino-6-methyl-7-chlorofluorane, 3-p- (p -Chloroanilino) anilino-6-methyl-7-chlorofluorane, 3,6-bis (dimethylamino) fluorene-9-spiro-3 '-(6'-dimethylamino) phthalide, etc. And the like. Of course, it is not limited to these, Moreover, 2 or more types can also be used together as needed. Among them, 3-di (n-butyl) amino-6-methyl-7-anilinofluorane, 3-di (n-pentyl) amino-6-methyl-7-anilinofluorane, and 3- (N -Ethyl-N-isoamylamino) -6-methyl-7-anilinofluorane is preferably used because it is excellent in color development sensitivity and print storage stability. The content of the leuco dye is about 5 to 25% by mass, preferably 7 to 20% by mass, based on the total solid content of the thermosensitive recording layer. By setting the content to 5% by mass or more, the coloring ability can be improved and the printing density can be improved. Heat resistance can be improved by setting it as 25 mass% or less.

  The heat-sensitive recording layer in the present invention contains N- [2- (3-phenylureido) phenyl] benzenesulfonamide as a colorant. As a result, it is possible to obtain a heat-sensitive recording material having a high recording density, excellent image stability, good background fogging at high temperature storage, and no color development after storage over time due to the influence of the pressure-sensitive adhesive component.

  In the present invention, the volume average particle diameter of N- [2- (3-phenylureido) phenyl] benzenesulfonamide is preferably 2 μm or less. Since the combination of colorants in the present invention is excellent in heat-resistant background fogging property in a high temperature environment, the particle diameter can be reduced, and the effect of increasing the recording density is excellent. The volume average particle diameter is preferably 0.1 μm or more, more preferably 0.2 μm or more, from the viewpoint of reduction in production efficiency due to prolonged dispersion time and reduction in background fog. On the other hand, from the viewpoint of improving the recording density, 1.0 μm or less is more preferable, and 0.6 μm or less is more preferable. The color former may be contained in the heat-sensitive recording layer as a dispersion having a specific volume average particle diameter.

  The heat-sensitive recording layer in the invention preferably further contains a urea urethane compound represented by the general formula (1) (hereinafter also referred to as a specific urea urethane compound) as a colorant. As a result, the image stability is excellent, the background fogging under high temperature storage is good, and an excellent effect is exhibited with respect to poor color development after storage over time due to the influence of the adhesive component. Specific examples of the specific urea urethane compound include, for example, 4,4′-bis [(4-methyl-3-phenoxycarbonylaminophenyl) ureido] diphenylsulfone, 4,4′-bis [(2-methyl-5 -Phenoxycarbonylaminophenyl) ureido] diphenylsulfone, 4- (2-methyl-3-phenoxycarbonylaminophenyl) ureido-4 '-(4-methyl-5-phenoxycarbonylaminophenyl) ureidodiphenylsulfone, and the like. These specific urea urethane compounds can be used singly or in combination of two or more.

  In this invention, it is preferable that the urea urethane compound represented by the said General formula (1) is what heat-processed in the same liquid as a basic inorganic pigment. For example, when the heat-sensitive recording layer is formed using a heat-sensitive recording layer coating liquid containing 4,4′-bis [(4-methyl-3-phenoxycarbonylaminophenyl) ureido] diphenylsulfone, 4,4′- -Bis [(4-methyl-3-phenoxycarbonylaminophenyl) ureido] diphenylsulfone was previously heat-treated in the same liquid as the basic inorganic pigment in the temperature range of 50 to 90 ° C., preferably 60 to 80 ° C. It can be blended in the thermal recording layer coating liquid as a dispersion. Thereby, after the thermal recording layer coating liquid is applied and dried to form the thermal recording layer, it is possible to suppress the occurrence of extra color development (background fogging) as the thermal recording body. The treatment time is appropriately adjusted depending on the heating temperature, but it is generally preferable to perform the heat treatment for 2 to 24 hours. The dispersion prior to the heat treatment is prepared by dispersing 4,4′-bis [(4-methyl-3-phenoxycarbonylaminophenyl) ureido] diphenylsulfone to a predetermined particle size and then mixing a basic inorganic pigment. It can also be obtained by mixing them and then dispersing them to a predetermined particle size.

  As the basic inorganic pigment, at least one selected from the group consisting of magnesium compounds, aluminum compounds, calcium compounds, titanium compounds, magnesium oxide, magnesium phosphate and talc is preferable. Of these, magnesium silicate, magnesium phosphate, and talc are preferably used from the viewpoint of the stability of the coating liquid and the coating suitability.

  Although the usage-amount of a basic inorganic pigment is not specifically limited, It is about 0.5-20 mass parts with respect to 100 mass parts of specific urea urethane compounds, Preferably it is about 1-10 mass parts.

  The content of the specific urea urethane compound in the thermosensitive recording layer is about 0.03 to 2.5 parts by mass with respect to 1 part by mass of N- [2- (3-phenylureido) phenyl] benzenesulfonamide. Is more preferable, and more preferably about 0.05 to 2.0 parts by mass. By setting it to 0.03 parts by mass or more, sufficient plasticizer resistance in the recording part can be obtained. On the other hand, the background fogging in a high temperature environment can be improved by setting it as 2.5 mass parts or less.

  The content of the specific urea urethane compound in the heat-sensitive recording layer is preferably 0.1 to 3.0 parts by mass, more preferably 0.2 to 2.5 parts by mass with respect to 1 part by mass of the leuco dye. More preferably, it is 0.5 to 2.0 parts by mass. The N- [2- (3-phenylureido) phenyl] benzenesulfonamide can be used by adjusting the content range.

  The content of N- [2- (3-phenylureido) phenyl] benzenesulfonamide in the heat-sensitive recording layer is preferably 0.5 to 5 parts by mass, more preferably 1 part by mass of the leuco dye. It is 0.8-4 mass parts, More preferably, it is 1-4 mass parts, Most preferably, it is 1.2-3.5 mass parts.

The color former in the present invention is N- [2- (3-phenylureido) phenyl] benzenesulfonamide, but various known materials can be used in combination as long as there is no problem. Specific examples include inorganic acidic substances such as activated clay, attapulgite, colloidal silica, aluminum silicate, 4,4′-isopropylidenediphenol, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 1 , 1-bis (4-hydroxyphenyl) cyclohexane, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 4,4′-dihydroxydiphenyl sulfide, hydroquinone monobenzyl ether, 4-hydroxy-4′- Benzyloxydiphenylsulfone, benzyl 4-hydroxybenzoate, 4-hydroxy-4′-isopropoxydiphenylsulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, 4-hydroxy-4′-methyldiphenylsulfone, 4- Allyloxy-4'-hydroxydi Phenyl compounds such as phenylsulfone, 3,4-dihydroxyphenyl-4′-methylphenylsulfone, thiourea compounds such as N, N′-di-m-chlorophenylthiourea, N- (p-toluenesulfonyl) carbamoyl acid p -Cumylphenyl ester, N- (p-toluenesulfonyl) carbamoyl acid p-benzyloxyphenyl ester, N- [2- (3-phenylureido) phenyl] benzenesulfonamide, N- (o-toluoyl) -p- Organic compounds having —SO ₂ NH— bond in the molecule such as toluenesulfoamide, p-chlorobenzoic acid, 4- [2- (p-methoxyphenoxy) ethyloxy] salicylic acid, 4- [3- (p-tolylsulfonyl) ) Propyloxy] salicylic acid, 5- [p- (2-p-methoxyphenoxyethoxy) ) Cumyl] Aromatic carboxylic acids such as salicylic acid, salts of these aromatic carboxylic acids with polyvalent metals such as zinc, magnesium, aluminum, calcium, titanium, manganese, tin, nickel, and further antipyrine complexes of zinc thiocyanate , Organic acidic substances such as complex zinc salts of terephthalaldehyde acid and other aromatic carboxylic acids, 4,4′-bis (3-tosylureido) diphenylmethane, 1,5- (3-oxopentylene) -bis (3 -(3 '-(p-toluenesulfonyl) ureido) benzoate, 1- (4-butoxycarbonylphenyl) -3-tosylurea, Np-toluenesulfonyl-N'-3- (p-toluenesulfonyloxy) phenylurea N- (p-toluenesulfonyl) -N′-phenylurea, N- (p-toluenesulfonyl) Sulfonylurea compounds such as N′-p-tolylurea, 4,4′-bis (3- (tosyl) ureido) diphenyl ether, 4,4′-bis (3- (tosyl) ureido) diphenylsulfone, the following general formula (2) The diphenyl sulfone derivative etc. which are represented by these are mentioned.

（式中、ｎは１〜６の整数を表す。）

(In the formula, n represents an integer of 1 to 6.)

  Various resins are usually used as binders in the thermal recording layer coating solution. Examples of the binder include starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, carboxy-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, diacetone-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, and diisobutylene. -Maleic anhydride copolymer salt, ethylene-acrylic acid copolymer salt, styrene-butadiene copolymer, urea resin, melamine resin, amide resin, polyurethane resin and the like. At least one of these is blended in the total solid content of the heat-sensitive recording layer, preferably in the range of about 5 to 50% by mass, more preferably about 10 to 40% by mass. When the medium for the thermal recording layer coating liquid is water, the hydrophobic resin is used in the form of latex.

  In the heat-sensitive recording material of the present invention, the heat-sensitive recording layer may further contain a preservability improver, a sensitizer, and other various auxiliary agents in addition to the specific colorant, leuco dye, and binder. .

  In the heat-sensitive recording layer of the present invention, a storability improving agent can be contained. Thereby, the preservability of a recording part can be improved. Examples of the preservability improver include 2,2′-methylenebis (4-methyl-6-tert-butylphenol), 2,2′-methylenebis (4-ethyl-6-tert-butylphenol), 2,2′-ethylidene. Bis (4,6-di-tert-butylphenol), 4,4′-thiobis (2-methyl-6-tert-butylphenol), 4,4′-butylidenebis (6-tert-butyl-m-cresol), 1 -[Α-methyl-α- (4'-hydroxyphenyl) ethyl] -4- [α ', α'-bis (4'-hydroxyphenyl) ethyl] benzene, 1,1,3-tris (2-methyl -4-hydroxy-5-cyclohexylphenyl) butane, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, (2,6-dimethyl-4-tertiarybutyl-3-hydroxybenzyl) isocyanurate, 4,4'-thiobis (3-methylphenol), 4,4'-dihydroxy-3,3 ', 5,5 '-Tetrabromodiphenylsulfone, 4,4'-dihydroxy-3,3', 5,5'-tetramethyldiphenylsulfone, 2,2-bis (4-hydroxy-3,5-dibromophenyl) 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; 1,4-diglycidyloxybenzene; 4,4′-diglycidyloxydiphenylsulfone, 4-benzyloxy-4 ′-(2-methylglycidyloxy) diphenylsulfur Hong, diglycidyl terephthalate, cresol novolac epoxy resin, phenol novolac epoxy resin, epoxy compound such as bisphenol A epoxy resin, N, N′-di-2-naphthyl-p-phenylenediamine, 2,2′-methylenebis Examples thereof include sodium or polyvalent metal salt of (4,6-di-tert-butylphenyl) phosphate, bis (4-ethyleneiminocarbonylaminophenyl) methane, and the like. The content of the storability improver may be an effective amount for improving the storability, but is usually preferably about 1 to 30% by mass, and 5 to 20% by mass in the total solid content of the thermosensitive recording layer. The degree is more preferable.

  The heat-sensitive recording layer in the present invention may contain a sensitizer. Thereby, the recording sensitivity can be increased. Examples of the sensitizer include myristic acid amide, palmitic acid amide, stearic acid amide, arachidic acid amide, methoxycarbonyl-N-stearic acid benzamylide, N-benzoyl stearic acid amide, ethylenebisstearic acid amide, behenic acid amide, Methylenebisstearic acid amide, N-methylol stearic acid amide, dibenzyl terephthalate, dimethyl terephthalate, dioctyl terephthalate, diphenylsulfone, benzyl p-benzyloxybenzoate, phenyl 1-hydroxy-2-naphthoate, 2-naphthylbenzyl Ether, m-terphenyl, p-benzylbiphenyl, oxalic acid di-p-chlorobenzyl ester, oxalic acid di-p-methylbenzyl ester, oxalic acid dibenzyl ester, p-tolylbiphe Ether, di (p-methoxyphenoxyethyl) ether, 1,2-di (3-methylphenoxy) ethane, 1,2-di (4-methylphenoxy) ethane, 1,2-di (4-methoxyphenoxy) ethane 1,2-di (4-chlorophenoxy) ethane, 1,2-diphenoxyethane, 1- (4-methoxyphenoxy) -2- (3-methylphenoxy) ethane, p-methylthiophenylbenzyl ether, 1, 4-di (phenylthio) butane, p-acetotoluizide, p-acetophenetide, N-acetoacetyl-p-toluidine, di (β-biphenylethoxy) benzene, p-di (vinyloxyethoxy) benzene, 1-isopropyl Examples include phenyl-2-phenylethane. These can be used in combination as long as there is no hindrance. Among them, stearamide, diphenylsulfone, 2-naphthylbenzyl ether, oxalic acid di-p-chlorobenzyl ester, oxalic acid di-p-methylbenzyl ester, 1,2-di (3-methylphenoxy) ethane, 1 , 2-Diphenoxyethane is preferably used because of its excellent color sensitivity. The content of the sensitizer may be an amount effective for sensitization, but is usually preferably about 2 to 40% by mass, and about 5 to 25% by mass in the total solid content of the heat-sensitive recording layer. More preferred.

  Examples of the auxiliary agent include sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate, fatty acid metal salt and the like, zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, ester wax and the like. Waxes, hydrazide compounds such as adipic acid dihydrazide, water resistant agents such as glyoxal, boric acid, glyoxylate, dialdehyde starch, methylol urea, epoxy compounds, antifoaming agents, colored dyes, fluorescent dyes, and pigments It is done.

  In the present invention, in order to improve the whiteness of the heat-sensitive recording layer and improve the uniformity of the image, a fine pigment having a high whiteness and an average particle diameter of 10 μm or less can be contained in the heat-sensitive recording layer. Specific examples include, for example, calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcined kaolin, amorphous silica, diatomaceous earth, synthetic aluminum silicate, zinc oxide, titanium oxide, aluminum hydroxide, barium sulfate, surface-treated carbonate. Inorganic pigments such as calcium and silica, and organic pigments such as urea-formalin resin, styrene-methacrylic acid copolymer resin, polystyrene resin and raw starch particles can be used. The content ratio of the pigment is preferably 50% by mass or less in an amount that does not decrease the color density, that is, in the total solid content of the heat-sensitive recording layer.

The heat-sensitive recording layer is, for example, water as a dispersion medium, a leuco dye, a specific colorant, if necessary, a sensitizer, a preservability improver, etc., or separately, a stirrer / crusher such as a ball mill, attritor, sand mill, etc. The coating solution for the heat-sensitive recording layer prepared by mixing and stirring a dispersion finely dispersed so that the average particle diameter becomes 2 μm or less, and if necessary, a pigment, a binder, an auxiliary agent, etc. preferably 2~12g / ^{m 2,} more preferably about so that 3 to 10 g / ^{m 2} approximately, coated on the support is formed and dried.

  In the present invention, an undercoat layer containing a pigment and a binder is provided on a support. Furthermore, the undercoat layer contains a sizing agent. The sizing agent is anionic and is at least one selected from styrene-acrylic copolymer resins and styrene-maleic acid copolymer resins. An anionic styrene-maleic acid copolymer resin is preferable. Thereby, even when neutral paper or acidic paper is used as the support, the background fogging and the white paper storage stability are excellent. In addition, even when the pressure-sensitive adhesive label is processed, it is possible to suppress color development defects after storage due to the influence of the pressure-sensitive adhesive component, and color can be developed at an initial recording density before storage. The reason for this is not clear, but it is a surfactant that enhances the barrier properties of the undercoat layer, and the sensitizer and colorant in the heat-sensitive recording layer are contained in the alkali filler or acidic ions in the support or in the adhesive. This is thought to be because the effect of the specific colorant in the present invention can be exhibited without regret.

  The content of the sizing agent in the undercoat layer is not particularly limited, but is preferably 0.1 to 1.0 part by mass with respect to 1 part by mass of N- [2- (3-phenylureido) phenyl] benzenesulfonamide. 0.1-0.7 mass part is more preferable, and 0.2-0.7 mass part is still more preferable.

  The sizing agent in the present invention is preferably in the form of an ammonium salt. By using an ammonium salt, there is no fear that the thermal head is electrically corroded by, for example, a sodium salt. Furthermore, it is preferable that the form is a solution type. If it is an emulsion type, it bleeds upward during the drying process of the undercoat layer, and it is difficult to form a uniform layer by sinking the pigment to the support side, which may impair the barrier property against the adhesive layer. By doing so, a uniform layer can be formed and a barrier property can be exhibited.

  The content of the sizing agent in the undercoat layer is not particularly limited, but is preferably 1 to 20% by mass, more preferably 2 to 10% by mass, and still more preferably 4 to 10% by mass in the total solid content of the undercoat layer. . When the content is 1% by mass or more, sufficient barrier properties can be obtained, and when the content is 20% by mass or less, sufficient recording sensitivity can be obtained.

  In the present invention, the sizing agent contained in the undercoat layer is at least one selected from anionic styrene-acrylic copolymer resins and styrene-maleic acid copolymer resins, but various types can be used as long as necessary. Known materials can be used in combination. Specific examples include rosin sizing agents, alkyl ketene dimer sizing agents, alkenyl succinic anhydrides, cationic polymer sizing agents, rosin neutral sizing agents, olefin sizing agents, wax sizing agents, silicon sizing agents, etc. It has a hydrophilic group and a hydrophobic group called a sizing agent for papermaking, and can be used alone or in combination of two or more.

  In the present invention, it is preferable to have an undercoat layer containing plastic hollow particles between the support and the thermosensitive recording layer. Thereby, the recording sensitivity can be further increased. Further, the plastic hollow particles stay on the support to form a uniform undercoat layer, whereby the thickness of the coating layer provided on the undercoat layer can be made uniform, and the barrier property can be improved.

  Examples of the plastic hollow particles include conventionally known particles, for example, particles having a hollow ratio of about 50 to 99% in which the film material is made of an acrylic resin, a styrene resin, a vinylidene chloride resin, or the like. Here, the hollowness is a value obtained by the following formula (d / D) × 100. In the formula, d represents the inner diameter of the organic hollow particles, and D represents the outer diameter of the organic hollow particles. The average particle size of the plastic hollow particles is preferably about 0.5 to 10 μm, more preferably about 1 to 3 μm. By setting the average particle size to 10 μm or less, when the undercoat layer coating solution is applied by a blade coating method, troubles such as streaks and scratches are not caused, and good coating suitability can be obtained.

  The content ratio of the plastic hollow particles can be selected from a wide range, but is generally preferably about 2 to 90% by mass in the total solid content of the undercoat layer. From the viewpoint of improving the color development effect and enhancing the barrier property, the lower limit is more preferably 5% by mass or more, and further preferably 10% by mass or more. On the other hand, from the viewpoint of suppressing wrinkle adhesion to the thermal head, the upper limit is more preferably 80% by mass or less, further preferably 70% by mass or less, particularly preferably 60% by mass or less, and most preferably 50% by mass or less.

  From the viewpoint of improving the effect of suppressing wrinkle adhesion to the thermal head, the undercoat layer preferably contains an oil-absorbing pigment having an oil absorption amount of 70 ml / 100 g or more, particularly about 80 to 150 ml / 100 g. Moreover, a thermally expansible particle can also be contained. Here, the oil absorption is a value determined according to the method described in JIS K 5101.

  Various oil-absorbing pigments can be used, and specific examples include inorganic pigments such as calcined kaolin, amorphous silica, light calcium carbonate, and talc. The average particle diameter of the primary particles of these oil-absorbing pigments is preferably about 0.01 to 5 μm, particularly about 0.02 to 3 μm. The content of the oil-absorbing pigment can be selected from a wide range, but is generally preferably about 2 to 95% by mass and more preferably about 5 to 90% by mass in the total solid content of the undercoat layer.

  When the oil-absorbing inorganic pigment is used in combination with the plastic hollow particles, the oil-absorbing inorganic pigment and the plastic hollow particles are used within the above-mentioned content ratio, and the total amount of the oil-absorbing inorganic pigment and the plastic hollow particles is The total solid amount is preferably about 5 to 90% by mass, more preferably about 10 to 90% by mass, and still more preferably about 10 to 80% by mass.

For the undercoat layer, a coating solution for the undercoat layer prepared by mixing and stirring a specific sizing agent, plastic hollow particles, oil-absorbing pigment, binder, auxiliary agent, etc. is generally applied onto the support using water as a medium. And dried to form. The coating amount of the undercoat layer is not particularly limited, but is preferably about 3 to 20 g / m ² , more preferably about 5 to 12 g / m ² in terms of dry weight.

  As the binder, oxidized starch, starch-vinyl acetate graft copolymer, polyvinyl alcohol, styrene-butadiene latex and the like are preferable from the viewpoint of improving coating film strength. Although the content rate of a binder can be selected in a wide range, generally about 5-30 mass% is preferable in the total solid amount of an undercoat layer, and about 10-20 mass% is more preferable.

  In the present invention, if necessary, at least one protective layer may be provided on the heat-sensitive recording layer. As the protective layer, a protective layer that has been used in conventionally known thermal recording media can be used. The protective layer is mainly composed of a pigment and a binder, and can be formed by applying a protective layer coating liquid containing these and drying. In particular, a lubricant such as polyolefin wax or zinc stearate is preferably added to the protective layer for the purpose of preventing sticking to the thermal head, and an ultraviolet absorber can also be included. In addition, the added value of the product can be increased by providing a glossy protective layer.

  The protective layer preferably contains a water-soluble polymer and / or a synthetic resin emulsion as a main component as a binder.

  Examples of the water-soluble polymer include polyvinyl alcohols such as fully saponified or partially saponified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, diacetone-modified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, and silicon-modified polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, and carboxymethyl cellulose. And cellulose-based resins such as gelatin, casein, and alkali salts of ethylene-acrylic acid copolymers. Examples of the synthetic resin emulsion include latexes such as styrene-butadiene latex, acrylic latex, and urethane latex. Among these, acetoacetyl-modified polyvinyl alcohol and diacetone-modified polyvinyl alcohol are preferably used because they can improve the surface barrier properties and improve the storage stability such as chemical resistance.

  The total content of the water-soluble polymer and / or synthetic resin emulsion is preferably about 10 to 80% by mass, more preferably about 20 to 75% by mass, based on the total solid content of the protective layer. By setting it as 10 mass% or more, barrier property improves, surface strength can be raised, and paper dust can be reduced. On the other hand, sticking resistance can be improved by setting it as 80 mass% or less.

  When the water-soluble polymer and the synthetic resin emulsion are used in combination, the use ratio is preferably about 5 to 100 parts by mass of the synthetic resin emulsion with respect to 100 parts by mass of the water-soluble polymer.

  Examples of the pigment include inorganic pigments such as calcium carbonate, zinc oxide, aluminum oxide, titanium dioxide, amorphous silica, synthetic mica, aluminum hydroxide, barium sulfate, talc, kaolin, clay, calcined kaolin, nylon resin filler, urea -Organic pigments such as formalin resin filler and raw starch particles. Among these, kaolin and aluminum hydroxide are preferable because they have a small decrease in barrier properties against chemicals such as plasticizers and oils and a small decrease in recording density.

  The use ratio of the pigment is preferably about 5 to 80% by mass, and more preferably about 10 to 70% by mass in the total solid content of the protective layer. By setting the content to 5% by mass or more, it is possible to improve the sliding with the thermal head and to improve the sticking resistance and head resistance. On the other hand, by setting it as 80 mass% or less, barrier property can be improved and the function as a protective layer can be improved significantly.

  As the auxiliary agent, for example, lubricants such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, ester wax, sodium alkylbenzene sulfonate, sodium dioctyl sulfosuccinate, sulfone-modified polyvinyl alcohol, sodium acrylate glycol polyacrylate compound , Surfactants such as fluorosurfactants, silicon surfactants, phosphate ester surfactants, ether surfactants, or amphoteric surfactants such as betaines, aminocarboxylates, and imidazoline derivatives, Glyoxal, boric acid, dialdehyde starch, methylol urea, epoxy compound, hydrazine compound, etc., water resistance (crosslinking agent), hydrophobic polycarboxylic acid copolymer, UV absorber, fluorescent dye, coloring dye Mold release agents, antioxidants, and the like. The usage-amount of auxiliary agent can be suitably set from a wide range.

The coating amount of the protective layer coating liquid is not particularly limited, and a desired quality can be achieved if the dry weight is about 0.3 to 10 g / m ² , particularly about 0.5 to 8 g / m ² . The protective layer can be divided into two or more layers as required, and the composition and coating amount of each layer can be changed.

  In the present invention, the pressure-sensitive adhesive layer is preferably provided on the surface of the support opposite to the surface on which the heat-sensitive recording layer is provided, or on the surface provided with the heat-sensitive recording layer. By using a heat-sensitive recording material processed into a pressure-sensitive adhesive label having a pressure-sensitive adhesive layer, the excellent effects of the present invention can be exhibited without regret. Examples of the pressure-sensitive adhesive used in the present invention include those mainly composed of rubber-based materials such as natural rubber, styrene-butadiene rubber, polyisobutylene rubber, and isoprene rubber, and those mainly composed of vinyl ether-based materials. -The thing which has acrylic materials, such as a copolymer polymer which has ethylhexyl acrylate as a main monomer, as a main component, and the thing which has rubbery siloxane and resinous siloxane as a main component are mentioned. These can be used as emulsions, various solvents or solventless adhesives.

  When using a release sheet, the adhesive may be applied directly on the support to provide an adhesive layer, or the adhesive is applied to the release sheet surface of the release sheet to provide an adhesive layer, and then supported. It may be attached to the opposite side of the body to the thermosensitive recording layer, and the adhesive layer may be transferred and provided. In either case, it is desirable that the pressure-sensitive adhesive layer is used by sticking a release sheet and peeling it off as desired in order to prevent unnecessary adhesion except during use. On the other hand, in the no-separate type that does not use a release sheet, the heat-sensitive recording layer and the pressure-sensitive adhesive layer are laminated with a release layer or the like sandwiched between them, and the support and the pressure-sensitive adhesive layer are wound in a wound state. The effect of the present invention can be exhibited without regret because the pressure-sensitive adhesive component is affected by contact.

The release sheet is a high-density base paper such as glassine paper, clay-coated paper, kraft paper, or release base paper such as polylaminate paper in which polyethylene is laminated on high-quality paper, etc., and fluorine resin or silicone resin as a release agent And the like having a peel surface attached in a range of about 0.05 to 3 g / m ² by dry weight. For example, a roll coater, a knife coater, a bar coater, a slot die coater or the like is used as a method for applying the pressure-sensitive adhesive, and the coating amount is adjusted in a range of about 5 to 50 g / m ² in terms of dry weight.

  In the present invention, if necessary, a back surface layer mainly composed of a pigment and a binder can be provided on the surface of the support opposite to the surface on which the heat-sensitive recording layer is provided. As a result, the storage stability can be further improved, and the curl aptitude and the printer runnability can be improved. In addition, various known techniques in the heat-sensitive recording material manufacturing field such as providing a magnetic recording layer, a coating layer for printing, a thermal transfer recording layer, and an ink jet recording layer on the back surface can be added as necessary. .

  The method for applying each coating liquid is not particularly limited. For example, known coating methods such as air knife coating, varibar blade coating, pure blade coating, rod blade coating, short dwell coating, curtain coating, and die coating can be used. Either may be used. In addition, each coating solution may be applied and dried one layer at a time to form each layer, or the same coating solution may be applied in two or more layers. Furthermore, simultaneous multi-layer coating in which two or more layers are simultaneously coated may be performed. In the present invention, a smoothing process using a super calender or the like can be performed in any process after the formation of each layer or after the formation of all the layers.

  As a method for applying the coating solution for the undercoat layer, pure blade coating or rod blade coating is preferable from the viewpoint of improving the surface properties of the undercoat layer. Further, regarding the formation of the heat-sensitive recording layer and the protective layer, it is preferable to apply multiple layers simultaneously by curtain coating. Thereby, a uniform coating layer can be formed, the barrier property of the protective layer can be improved, and the productivity can be increased. Curtain coating is a method in which the coating liquid is allowed to flow down and fall freely and is applied to the support in a non-contact manner. Known methods such as the slide curtain method, the couple curtain method, and the twin curtain method can be employed. It is not limited. Further, as described in JP-A-2006-247611, the coating liquid is ejected downward from the curtain head to form a coating liquid layer on the slope, and the coating liquid is applied from the downward curtain guide portion of the slope. It is also possible to transfer the coating liquid layer onto the web surface by forming a curtain. Here, the simultaneous multilayer coating is a method in which two or more layers are coated simultaneously, and includes a method in which the upper layer is coated without drying after the lower layer is coated.

  In the present invention, from the viewpoint of increasing the recording sensitivity and improving the image uniformity, after completing the formation of each layer or after completing the formation of all the layers, a super calendar, a soft calendar, etc. It is preferable to perform a smoothing process using a known method.

  In the present invention, in order to further increase the added value of the product, a multicolor thermosensitive recording material can be used. In general, multicolor thermal recording materials are an attempt to utilize the difference in heating temperature or thermal energy, and are generally constructed by sequentially laminating a high-temperature coloring layer and a low-temperature coloring layer that develop colors in different colors on a support. These are roughly divided into two types, decoloring type and additive type, producing a multicolor thermal recording material using a method using microcapsules and composite particles composed of organic polymer and leuco dye. There is a way to do it.

  The present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. Unless otherwise specified, “part” and “%” in the examples indicate “part by mass” and “% by mass”, respectively.

Example 1
-Preparation of coating solution for undercoat layer Plastic hollow particle dispersion (trade name: Ropaque SN-1055, hollow ratio: 55%, average particle size: 1.0 μm, manufactured by Dow Chemical Co., Ltd., solid content concentration 26.5% by mass) 115 parts, calcined kaolin (trade name: Ancilex, manufactured by BASF) 50% aqueous dispersion (volume average particle size: 0.6 μm), 100 parts, styrene-butadiene latex (trade name: L-1571, Asahi Kasei Chemicals) 20 parts by weight, solid content concentration of 48% by mass), anionic styrene-maleic acid copolymer resin as sizing agent (trade name: Polymaron WR300DS, manufactured by Arakawa Chemical Co., Ltd., aqueous solution having a solid content concentration of 20% by mass, ammonium salt) A composition comprising 20 parts, 30 parts of a 10% aqueous solution of oxidized starch, and 20 parts of water was mixed and stirred to obtain a coating solution for an undercoat layer.

-Preparation of liquid A (leuco dye dispersion) 3-di (n-butyl) amino-6-methyl-7-anilinofluorane 100 parts, sulfone-modified polyvinyl alcohol (trade name: Goceran L-3266, Nippon Synthetic Chemical A composition consisting of 50 parts of a 20% aqueous solution of Kogyo Kogyo Co., Ltd., 10 parts of a 5% emulsion of a natural fat and oil-based antifoaming agent (trade name: Nopco 1407H, manufactured by San Nopco Co., Ltd.), and 90 parts of water is laser-diffracted by a sand mill. A liquid A was obtained by pulverizing until the median diameter was 0.5 μm using a particle size distribution analyzer SALD2200 (manufactured by Shimadzu Corporation).

-Preparation of liquid B (coloring agent dispersion) N- [2- (3-phenylureido) phenyl] benzenesulfonamide 100 parts, sulfone-modified polyvinyl alcohol (trade name: Gocelan L-3266, supra) 20% A composition comprising 50 parts of an aqueous solution, 10 parts of a 5% emulsion of a natural fat and oil-based antifoaming agent (trade name: Nopco 1407H, supra), and 90 parts of water was subjected to a laser diffraction particle size distribution analyzer SALD2200 (Shimadzu Corporation) using a sand mill. The liquid B was obtained by pulverizing until the median diameter was 0.6 μm.

-Preparation of liquid C (sensitizer dispersion) 100 parts of 1,2-di (3-methylphenoxy) ethane, 50 parts of a 20% aqueous solution of sulfone-modified polyvinyl alcohol (trade name: Gocelan L-3266, supra), A composition consisting of 2 parts of a 5% emulsion of a natural fat and oil-based antifoaming agent (trade name: Nopco 1407H, supra) and 98 parts of water was subjected to a laser diffraction particle size distribution analyzer SALD2200 (manufactured by Shimadzu Corporation) using a sand mill. C was obtained by pulverizing until the median diameter became 1.0 μm.

-Preparation of coating solution for heat sensitive recording layer A part 35 parts, B part 70 parts, C part 35 parts, aluminum hydroxide (trade name: Hygielite H-42, Showa Denko KK) 24 parts, saponification degree 98 mol% A composition comprising 120 parts of a 10% aqueous solution of polyvinyl alcohol having a polymerization degree of 1000, 5 parts of a 35% aqueous dispersion of adipic acid dihydrazide, 2 parts of a 10% aqueous solution of sodium dioctylsulfosuccinate, and 35 parts of water. A thermal recording layer coating solution was obtained.

Preparation of Liquid D (Kaolin Dispersion) Kaolin [trade name: UW-90 (registered trademark), manufactured by BASF Corp.] 50 parts, fine-particle amorphous silica (trade name: Mizuka Seal P-527, manufactured by Mizusawa Chemical Co., Ltd.) 4 Part D, a 40% aqueous solution of sodium polyacrylate (trade name: Aron T-50, manufactured by Toagosei Co., Ltd.) and a composition consisting of 0.4 parts of water and 81 parts of water were mixed to obtain liquid D.

-Preparation of coating solution for protective layer 135 parts of solution D, 250 parts of 10% aqueous solution of acetoacetyl-modified polyvinyl alcohol (trade name: Gohsephimer Z-200, polymerization degree 1000, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), zinc stearate 20 parts of an aqueous dispersion (trade name: Hydrin Z-8-36, solid concentration 36%, manufactured by Chukyo Yushi Co., Ltd.), ionomer-type urethane resin latex [trade name: Hydran (registered trademark) AP-30F, manufactured by DIC , Solid content concentration 20%] A composition comprising 45 parts and 1 part of a 10% aqueous solution of sodium dioctylsulfosuccinate was mixed to obtain a coating solution for a protective layer.

Heat-sensitive recording material woodfree paper having produced a basis weight of 64 g / m ² of the one surface of the (acid paper), blade an undercoat layer coating solution weight after drying using a blade coater so that 7 g / m ² A slide hopper type curtain coating apparatus was used so that the coating layer was coated and dried to form an undercoat layer, and the weight of the thermosensitive recording layer coating solution on the undercoat layer after drying was 3.5 g / m ² . Apply by curtain coating method and dry to form a heat-sensitive recording layer, and apply the protective layer coating liquid on the heat-sensitive recording layer by curtain coating method so that the coating amount after drying is 2.5 g / m ^2. After drying to form a protective layer, a super calender treatment was performed to obtain a heat-sensitive recording material.

Adhesive labels processed pressure-sensitive adhesive layer which main component an adhesive for manufacturing an acrylic resin heat-sensitive recording material to the release surface of the release base paper 20 g / m ² provided, attached to the other surface of the adhesive layer and the high quality paper In addition, a heat-sensitive recording material processed with an adhesive label was obtained.

Example 2
In the preparation of the coating liquid for the undercoat layer of Example 1, a heat-sensitive recording material having an adhesive label processed was obtained in the same manner as in Example 1 except that the amount of the sizing agent was changed to 10 parts instead of 20 parts.

Example 3
In the preparation of the coating liquid for the undercoat layer of Example 1, a heat-sensitive recording material subjected to pressure-sensitive adhesive label processing was obtained in the same manner as in Example 1 except that the amount of the sizing agent was changed to 50 parts instead of 20 parts.

Example 4
In the preparation of the coating liquid for the undercoat layer of Example 1, the type and amount of the sizing agent were changed to anionic styrene-acrylic acid copolymer resin (trade name: Polymeralon E-100, manufactured by Arakawa Chemical Co., Ltd., solid content concentration: 30% by mass. ) A heat-sensitive recording material having an adhesive label processed in the same manner as in Example 1 except that 13.5 parts was used.

-Preparation of liquid E (colorant dispersion) 100 parts of the compound represented by the general formula (2) (trade name: UU, manufactured by Chemipro Kasei Co., Ltd.), sulfone-modified polyvinyl alcohol (trade name: Goceran L-3266, front A composition comprising 50 parts of a 20% aqueous solution of No. 1), 2 parts of a 5% emulsion of a natural fat and oil-based antifoaming agent (trade name: Nopco 1407H, supra), and 98 parts of water using a sand mill. The liquid E was obtained by pulverizing until the median diameter was 1.0 μm using an apparatus SALD2200 (manufactured by Shimadzu Corporation).

Example 5
In the preparation of the heat-sensitive recording layer coating liquid of Example 1, a heat-sensitive recording material having an adhesive label processed was obtained in the same manner as in Example 1 except that 25 parts of E liquid was further added.

Example 6
In the preparation of the thermal recording layer coating liquid of Example 5, the same as Example 5 except that the amount of B liquid was changed to 70 parts instead of 70 parts and the amount of E liquid was changed to 5 parts instead of 25 parts. Thus, a heat-sensitive recording material having an adhesive label was obtained.

Example 7
In the preparation of the thermal recording layer coating liquid of Example 5, the same as Example 5 except that the amount of B liquid was 35 parts instead of 70 parts and the amount of E liquid was 60 parts instead of 25 parts. Thus, a heat-sensitive recording material having an adhesive label was obtained.

-Preparation of liquid F (coloring agent dispersion) 4,4'-bis [(4-methyl-3-phenoxycarbonylaminophenyl) ureido] diphenylsulfone 100 parts, magnesium silicate 5 parts, sulfone-modified polyvinyl alcohol ( Brand name: Go-Selan L-3266, manufactured by Nippon Synthetic Chemical Co., Ltd.) 50% 20% aqueous solution, natural fat-based antifoaming agent (trade name: Nopco 1407H, San Nopco) 10% 5% emulsion, and water 90 The composition consisting of parts was pulverized by a sand mill with a laser diffraction particle size distribution analyzer SALD2200 (manufactured by Shimadzu Corporation) until the median diameter became 1.0 μm to obtain a dispersion. Further, the dispersion was subjected to a heat treatment at 70 ° C. for 4 hours to obtain a liquid F.

Example 8
In the preparation of the thermal recording layer coating liquid of Example 5, an adhesive label processed thermosensitive recording material was obtained in the same manner as in Example 5 except that the F liquid was used instead of the E liquid.

Comparative Example 1
In the preparation of the liquid B of Example 1, the same procedure as in Example 1 was conducted except that 4,4′-dihydroxydiphenylsulfone was used instead of N- [2- (3-phenylureido) phenyl] benzenesulfonamide. A heat-sensitive recording material processed with an adhesive label was obtained.

Comparative Example 2
In the preparation of the coating liquid for the undercoat layer of Example 1, a thermosensitive recording material that was subjected to pressure-sensitive adhesive label processing in the same manner as in Example 1 except that an anionic styrene-maleic acid copolymer resin was not used as a sizing agent. Obtained.

Comparative Example 3
In the preparation of the coating solution for the undercoat layer of Example 1, a cationic alkyl ketene dimer emulsion (trade name: Size Pine K921, 20%) was used instead of 20 parts of the anionic styrene-maleic acid copolymer resin as a sizing agent. Except for using 20 parts (concentration, manufactured by Arakawa Chemical Industry Co., Ltd.), a heat-sensitive recording material having been subjected to adhesive label processing was obtained in the same manner as in Example 1.

  The following evaluation was performed about the pressure-sensitive adhesive label for thermal recording thus obtained. The results were as shown in Table 1.

(Recording density)
Using a thermal recording evaluation machine (trade name: TH-PMH, manufactured by Okura Electric Co., Ltd.), each thermal recording body is printed with applied energy of 0.16 mJ / dot and 0.28 mJ / dot, and the optical density of the recording portion is determined. The measurement was performed in the visual mode of a reflection densitometer (trade name: Macbeth densitometer RD-918, manufactured by Gretag Macbeth). The larger the value, the darker the print density.

(Alcohol resistance)
Using a thermal recording evaluation machine (trade name: TH-PMH, manufactured by Okura Electric Co., Ltd.), each thermal recording body colored with an applied energy of 0.28 mJ / dot is immersed in a 20% ethanol solution for 30 minutes and dried. After the treatment, the optical density of the recording portion was measured in a visual mode of a reflection densitometer (trade name: Macbeth densitometer RD-918, manufactured by Gretag Macbeth). Further, the storage ratio of the recording part was obtained by the following formula.
Storage rate (%) = (recording density after processing / recording density before processing) × 100

(Plasticizer resistance)
A wrap film (trade name: High Wrap KMA-W, manufactured by Mitsui Chemicals Co., Ltd.) is wound on a polycarbonate pipe (40 mmΦ) in a triple layer, and each thermosensitive recording medium colored for recording density measurement is placed on the wrap film. Wrap film is wrapped in three layers, and the density of the recorded part is measured in the visual mode of Macbeth densitometer (trade name: RD-914, Macbeth Co., Ltd.) after being left and processed in an environment of 40 ° C. for 24 hours. did. Further, the storage ratio of the recording part was obtained by the following formula.
Storage rate (%) = (recording density after processing / recording density before processing) × 100

(Color development after long-term storage)
In order to evaluate the change in recording sensitivity due to long-term storage, as an accelerated test, a thermal recording material was stored for 3 days in an environment of 50 ° C. and 90% RH, and then a thermal recording evaluation machine (trade name: TH-PMH, Okura Electric Co., Ltd.). The thermal recording medium was printed at an applied energy of 0.16 mJ / dot and 0.28 mJ / dot using a reflection densitometer (trade name: Macbeth densitometer RD-918). It was measured in the visual mode of Gretag Macbeth. The smaller the recording density difference from before storage, the lower the color development defect and the better the storage of white paper.

  The heat-sensitive recording material obtained by the present invention has high recording sensitivity, excellent image stability, good background fogging under high-temperature storage, and does not have poor color development after storage over time due to the influence of the pressure-sensitive adhesive component. Can be suitably used as a label application.

Claims (11)

  In a heat-sensitive recording material comprising an undercoat layer containing a pigment and a binder on a support, and a heat-sensitive recording layer containing a leuco dye and a colorant on the undercoat layer, an anionic styrene-acrylic copolymer resin as a sizing agent and A thermosensitive material comprising at least one selected from styrene-maleic acid copolymer resin in an undercoat layer and N- [2- (3-phenylureido) phenyl] benzenesulfonamide as the colorant. Recorded body.   The thermal recording according to claim 1, wherein the sizing agent is contained in an amount of 0.1 to 1.0 part by mass with respect to 1 part by mass of the N- [2- (3-phenylureido) phenyl] benzenesulfonamide. body.   The heat-sensitive recording material according to claim 1, wherein a pressure-sensitive adhesive layer is provided on the surface of the support opposite to the surface provided with the heat-sensitive recording layer, or on the surface provided with the heat-sensitive recording layer.   The heat-sensitive recording material according to any one of claims 1 to 3, wherein the sizing agent is contained in a proportion of 1 to 20% by mass in the total solid content of the undercoat layer. The heat-sensitive recording material according to any one of claims 1 to 4, further comprising a urea urethane compound represented by the following general formula (1) as the colorant.

  The urea urethane compound represented by the general formula (1) is contained at 0.03 to 2.5 parts by mass with respect to 1 part by mass of the N- [2- (3-phenylureido) phenyl] benzenesulfonamide. The heat-sensitive recording material according to claim 5.   The heat-sensitive recording material according to claim 5 or 6, wherein the urea urethane compound represented by the general formula (1) is heat-treated in the same liquid as the basic inorganic pigment.   The heat-sensitive recording material according to claim 7, wherein the basic inorganic pigment is at least one selected from the group consisting of a magnesium compound, an aluminum compound, a calcium compound, a titanium compound, magnesium silicate, magnesium phosphate, and talc.   The heat-sensitive recording material according to claim 1, wherein the undercoat layer contains plastic hollow particles.   The heat-sensitive recording material according to claim 1, further comprising an undercoat layer formed by a blade coating method between the support and the heat-sensitive recording layer.   The heat-sensitive recording material according to claim 1, wherein at least one layer formed on the support is formed by a curtain coating method.