JP2009113264A - Thermosensible recording medium and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermosensible recording medium and its manufacturing method having a high degree of luster and high density in recording, excellent in the recorded picture quality, and free of generation of cracks at the recorded surface. <P>SOLUTION: The thermosensible recording medium is structured so that an intermediate layer containing resin as major component, a barrier layer containing aqueous resin provided according to necessity, a thermosensible recording layer containing an electron giving compound and an electron receiving compound, and one or more protection layers containing aqueous resin are formed on one surface of a support in this order, wherein the protection layer at least adjoining to the thermosensible recording layer contains polyvinyl alcohol having a degree of polymerization of 200-600, while the protection layer as the outermost has a surface transcribed onto the support from the base material having a flat surface. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a heat-sensitive recording material utilizing a color reaction by heat between a leuco dye and a colorant and a method for producing the same, and particularly has high glossiness and recording density, excellent recording image quality, and does not cause cracks on the recording surface. The present invention relates to a heat-sensitive recording material and a method for producing the same.

  2. Description of the Related Art Conventionally, a heat-sensitive recording material using a color development reaction caused by heat between a leuco dye and a color former is well known. Such a thermal recording medium is relatively inexpensive, and the recording apparatus is compact and relatively easy to maintain, so that it can be used not only as a facsimile, various labels, or other output recording media, It is also widely used as a recording medium used in printers of medical diagnostic apparatuses such as line image diagnosis.

  Among them, in a printer of a medical diagnostic apparatus that requires uniformity of recorded images and high resolution, a synthetic paper having a multilayer structure and a biaxially stretched resin film containing an inorganic pigment as necessary are used as a support. A thermal recording medium is used. In recent years, there has been an increasing demand for a thermal recording material that is excellent in gradation reproducibility from low density to high density and that can obtain a high-quality and high-gloss recording image comparable to silver salt photography.

  As such a heat-sensitive recording material, a heat-sensitive recording material in which the surface of the protective layer is a cast surface has been proposed (see Patent Document 1). In order to make the surface of the protective layer a cast surface, the first member in which a part or all of the layers including the overcoat layer are formed on the smooth surface of the film, and the remaining layers not formed in the first member There has been proposed a method of peeling a film after laminating a second member made of a base material on which a film is formed (see Patent Document 2). Further, a method has been proposed in which a protective layer and a thermosensitive recording layer are provided on a mirror drum, and then the protective layer and the thermosensitive recording layer are transferred from the mirror drum onto a support (see Patent Document 3). However, in the method of forming a layer on a substrate having such a smooth surface, the recording surface is liable to crack in the process of applying and drying and laminating on a highly smooth substrate, and the glossiness is lowered. However, since not only the unrecorded portion but also the recorded portion is cracked and the recording density and the recording image quality are inferior, further improvement is desired.

JP-A-63-205278 Japanese Patent Laid-Open No. 11-321111 JP 2002-234251 A

  An object of the present invention is to provide a thermal recording material having high glossiness and recording density, excellent recording image quality, and no cracking on the recording surface, and a method for producing the same.

  As a result of intensive studies in view of the above-described conventional techniques, the present inventors have at least a protective layer adjacent to the heat-sensitive recording layer containing polyvinyl alcohol having a polymerization degree of 200 to 600 (hereinafter sometimes referred to as specific PVA). The above-mentioned problems have been solved by having the protective layer as the outermost layer having a surface transferred from a substrate having a smooth surface to a support. That is, the present invention relates to the following thermal recording material and a method for producing the same.

  Item 1: An intermediate layer containing a resin as a main component on one side of a support, a barrier layer containing an aqueous resin provided as necessary, a heat-sensitive recording layer containing an electron donating compound and an electron accepting compound And a thermal recording material having a protective layer containing one or two or more aqueous resins in this order, at least the protective layer adjacent to the thermal recording layer contains polyvinyl alcohol having a polymerization degree of 200 to 600, A heat-sensitive recording material, wherein the protective layer as an outer layer has a surface transferred from a substrate having a smooth surface onto a support.

  Item 2: The heat-sensitive recording material according to Item 1, wherein the intermediate layer contains an ultraviolet ray or an electron beam curable resin as a main component and is cured by irradiation with ultraviolet rays or an electron beam.

  Item 3: The support is either synthetic paper, resin film, or a laminate of resin film and paper, and the substrate having a smooth surface is either a resin film, a mirror-plated metal drum, or an endless belt Item 3. The thermal recording material according to Item 1 or 2, wherein

  Item 4: An intermediate layer containing a resin as a main component on one surface of a support, a barrier layer containing an aqueous resin provided as necessary, a heat-sensitive recording layer containing an electron donating compound and an electron accepting compound And a thermal recording material having a protective layer containing one or two or more aqueous resins in this order, at least the protective layer adjacent to the thermal recording layer contains polyvinyl alcohol having a polymerization degree of 200 to 600, The outer layer is a method for producing a thermosensitive recording medium having a surface transferred from a substrate having a smooth surface to a support, the outermost layer being formed on the substrate having a smooth surface in advance. A protective layer having a protective layer disposed on the side closest to the substrate, a heat-sensitive recording layer, and if necessary, a barrier layer are provided in this order, and one surface of the support and the heat-sensitive recording layer or barrier layer are interposed via an intermediate layer. Bonding the surface of The method of manufacturing a heat-sensitive recording material, characterized in that peeling between the protective layer of the surface and the outermost layer of the substrate having a smooth surface.

  Item 5: A protective layer in which a protective layer serving as the outermost layer is disposed on the side closest to the base material, a heat-sensitive recording layer, and a barrier layer as necessary are provided in this order on a base material having a smooth surface in advance, One surface of the support and the surface of the heat-sensitive recording layer or barrier layer are bonded via an uncured intermediate layer containing an electron beam curable resin as a main component, and the intermediate layer is irradiated with ultraviolet rays or an electron beam. Item 5. The method for producing a heat-sensitive recording material according to Item 4, wherein the cured surface is peeled between the surface of the substrate having a smooth surface and the protective layer that is the outermost layer.

  Item 6: The method for producing a heat-sensitive recording material according to Item 4 or 5, wherein at least a heat-sensitive recording layer and an adjacent protective layer are simultaneously coated on a substrate having a smooth surface.

  According to the present invention, it is possible to provide a thermal recording material having high glossiness and recording density, excellent recording image quality, and no cracking on the recording surface, and a method for producing the same.

The support used in the present invention is preferably either synthetic paper, a resin film, or a laminate of a resin film and paper. As the support, for example, a thermoplastic polyolefin resin and a white inorganic pigment are heat-kneaded, extruded from a die, and stretched in the longitudinal direction. Laminated layers are stretched in the transverse direction to make them translucent or opaque, and thermoplastic paper such as synthetic paper, polyethylene, polypropylene, polystyrene, polyester, etc. or a mixture of them is heated and kneaded, extruded from a die and biaxially stretched. In addition to resin films obtained by mixing these resins with white inorganic pigments and biaxially stretched opaque films or unstretched resin films, high-quality paper, medium-quality paper, neutral paper, recycled A laminate or the like in which resin is coated on one side or both sides of paper manufactured from pulp fibers such as paper and coated paper can be used. The basis weight of such supports is about 30 to 200 g / m ^2.

  The base material having a smooth surface used in the present invention preferably has a high gloss and a high smooth surface, and the base material having a smooth surface has a glossiness of 90% or higher by setting the 75 ° specular gloss to 90% or more. Therefore, a more excellent thermal recording material can be obtained. Moreover, peelability can be improved by having apply | coated the release agent on the base-material surface. Examples of the substrate include polyester films (PET films), polypropylene films, polystyrene films, polycarbonate films, nylon films, and other resin films, mirror-plated metal drums, and endless belts. . Especially, a resin film is preferable and the thickness is preferably about 10 to 500 μm. In particular, a polyester film with less expansion and contraction during drying is more preferable.

  The protective layer in the present invention comprises a protective layer containing one or two or more aqueous resins. Thereby, not only the glossiness of the surface (recording surface) of the heat-sensitive recording material can be improved, but also the barrier property against a solvent such as alcohol can be improved and the good storage property of the heat-sensitive recording layer can be obtained. When providing a protective layer in a multilayer, the composition of a protective layer does not need to be the same, and it is preferable to contain a pigment in the protective layer used as an outermost layer at least from a viewpoint of improving printer suitability. In the present invention, from the viewpoint of barrier properties and printer suitability, it is preferable to provide one or two protective layers containing at least an aqueous resin.

  As the aqueous resin, either a water-soluble resin or a water-dispersible resin can be used. Examples of the water-soluble resin include starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, arabic gum, fully (or partially) saponified polyvinyl alcohol, silicon-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, Diacetone modified polyvinyl alcohol, diisobutylene / maleic anhydride copolymer salt, styrene / maleic anhydride copolymer salt, ethylene / acrylic acid copolymer salt, styrene / acrylic acid copolymer salt, methyl vinyl ether / maleic anhydride Examples thereof include copolymer salts, isopropylene / maleic anhydride copolymer salts, and polyacrylamides. Examples of the water-dispersible resin include vinyl acetate latex, styrene / butadiene latex, acrylic latex, urethane latex, and the like.

  As for content of aqueous resin, about 10-60 mass% is preferable with respect to the total solid in the protective layer used as the outermost layer. The barrier property can be improved by setting it to 10% by mass or more, and the suitability of the printer can be improved by setting it to 60% by mass or less. On the other hand, when the protective layer is provided in a multi-layer, if the pigment ratio of the outermost layer is increased from the viewpoint of printer suitability, the barrier property against a solvent such as alcohol is reduced, so that the aqueous layer in other protective layers other than the outermost protective layer As content of resin, about 20-95 mass% is preferable with respect to the total solid in a single protective layer, and about 30-95 mass% is more preferable. Thereby, barrier property can be improved and it can be made compatible with printer aptitude.

  Examples of the pigment contained in the protective layer include kaolin, clay, aluminum hydroxide, calcined clay, colloidal silica, calcium carbonate, zinc oxide, aluminum oxide, titanium oxide, diatomaceous earth, amorphous silica, barium sulfate, talc, and styrene resin. Examples include fillers, nylon resin fillers, urea / formalin resin fillers, and the like. The mass ratio of the pigment to the aqueous resin (pigment / aqueous resin) in the protective layer serving as the outermost layer is preferably about 30/70 to 90/10 from the viewpoint of further improving the printer suitability.

  The protective layer may contain additives such as a lubricant, a crosslinking agent, and a surfactant. Examples of additives include lubricants such as alkyl phosphate, stearamide, zinc stearate and calcium stearate, waxes such as carnauba wax and paraffin wax, diacids such as boric acid, borax, glyoxal and dialdehyde starch. Aldehyde compounds, polyamide / epichlorohydrin resins, melamine resins, dimethylol urea compounds, crosslinking agents such as adipic acid dihydrazide, surfactants such as dialkyl sulfosuccinates, alkyl sulfonates, alkyl carboxylates, alkyl ethylene oxides, Fluorosurfactants, antifoaming agents, fluorescent whitening agents, colored dyes and the like can be mentioned. Among these, a salt of an alkyl phosphate ester, preferably a salt of an alkyl phosphate ester having 8 to 24 carbon atoms, is in the range of about 0.1 to 5% by mass with respect to the total solid content in the protective layer that is the outermost layer. By containing, the suitability of the printer can be further improved.

  In the present invention, the protective layer serving as the outermost layer has a surface transferred from a substrate having a smooth surface onto a support. Thereby, a heat-sensitive recording material having a high glossiness can be obtained.

  The method of providing the outermost layer transferred from the substrate having a smooth surface onto the support is as follows: (1) a substrate having a smooth surface in a wet state in which the outermost layer is not dried or rewet after drying. Bonding with material surface, drying while bonded, peeling from substrate having smooth surface after drying, (2) (a) Adhering at least outermost layer provided on substrate having smooth surface in advance (2) (b) a smooth surface in advance, which is bonded to a layer including a heat-sensitive recording layer provided on one surface of a support and peeled from a substrate having a smooth surface There is a method in which a layer including at least an outermost layer and a heat-sensitive recording layer provided on a substrate having a surface is bonded to one surface of a support via an adhesive substance and peeled from a substrate having a smooth surface. Can be mentioned.

  The substance having adhesiveness may be applied to at least one of the surface of the layer to be bonded and the surface of the support, or may be contained in any of the layers to be bonded. If it is necessary to dry the substance having adhesiveness or a layer containing the same, it may be dried while being bonded, and the outermost layer may be peeled off from the substrate having a smooth surface after drying. The adhesive material in the present invention is preferably applied or contained on the side closer to the heat-sensitive recording layer as viewed from the support, from the viewpoint of further improving the recording image quality. Furthermore, in the heat-sensitive recording material of the present invention, an embodiment in which an adhesive substance is contained as a resin in the intermediate layer is preferable because the effects of the present invention can be fully exhibited. Thereby, at least the heat-sensitive recording layer and the adjacent protective layer can be applied at the same time, and the productivity can be remarkably improved.

  In the present invention, at least the protective layer adjacent to the thermosensitive recording layer contains polyvinyl alcohol having a polymerization degree of 200 to 600. As a result, it is possible to obtain a thermal recording material having high glossiness and recording density and excellent recording image quality without causing cracks on the recording surface. By setting the degree of polymerization to 200 or more, the coating suitability of the protective layer can be improved. If the degree of polymerization exceeds 600, the water-based resin swollen by moisture will shrink and cause cracks on the recording surface of the heat-sensitive recording medium while the protective layer shifts from the wet state to the dry state. By setting it to 600 or less, it is possible to obtain a heat-sensitive recording material in which no cracks occur on the recording surface. The degree of polymerization referred to in the present invention is the average degree of polymerization determined by the method described in JIS K6726-1994.

  The specific PVA is not particularly limited, and examples thereof include fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, diacetone-modified polyvinyl alcohol, and silicon-modified polyvinyl alcohol. Can be mentioned. Of these, acetoacetyl-modified polyvinyl alcohol is preferable from the viewpoint of water resistance.

  The proportion of the specific PVA is preferably within the range of the content of the aqueous resin described above even when other aqueous resin is used in combination in order not to impair the effects of the present invention. When providing a protective layer in a multilayer, it is preferable that content of specific PVA shall be 30 mass% or more with respect to the total solid in the protective layer adjacent to a thermosensitive recording layer. Thereby, it can suppress effectively that a crack generate | occur | produces on a recording surface.

The protective layer is, for example, a protective layer coating solution prepared by mixing and stirring an aqueous resin, pigment, additive, and the like using water as a medium on a substrate having a smooth surface in advance. It is formed by placing and drying the layer on the side closest to the substrate. The coating amount after drying of a single protective layer, about 0.5~7g / ^{m 2} is preferred. When the coating amount of the protective layer is 0.5 g / m ² or more, the coating film can be formed uniformly, and when it is 7 g / m ² or less, the recording sensitivity and the recording density can be improved. The outermost protective layer is more preferably about 0.5 to 5 g / m ^{2 and} particularly preferably about 0.5 to 3.5 g / m ² as the coating amount after drying.

  The heat-sensitive recording layer in the present invention may be any material that can form a recorded image by heating, and can contain various known electron-donating compounds and electron-accepting compounds as color forming components. Moreover, you may contain a preservability improving agent, a sensitizer, etc. as needed. Examples of the color forming component include a combination of a leuco dye and a colorant, a combination of an imino compound and an isocyanate compound, a combination of a long-chain fatty acid metal salt and a polyhydric phenol, a chelate with a transition element such as iron, cobalt, or copper. Examples include combinations with compounds. Hereinafter, a combination of a leuco dye having a characteristic excellent in recording sensitivity and recording density and a colorant will be described in detail.

  Examples of leuco dyes include 3-diethylamino-6-methyl-7-anilinofluorane, 3-di (n-butyl) amino-6-methyl-7-anilinofluorane, and 3-di (n-pentyl). ) Amino-6-methyl-7-anilinofluorane, 3-piperidino-6-methyl-7-anilinofluorane, 3- (N-methyl-N-cyclohexyl) amino-6-methyl-7-anilino Fluorane, 3-diethylamino-7- (m-trifluoromethyl) anilinofluorane, 3- (N-ethyl-N-tetrahydrofurfuryl) amino-6-methyl-7-anilinofluorane, 3- ( N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluorane, 3-di (n-butyl) amino-7- (o-chloroanilino) fluorane, 3- (N-ethyl) -p- toluidino) -6-methyl-7-anilinofluoran, 3- (N-ethyl--p- toluidino) -6-methyl-7- (p-toluidino) fluoran, and the like. Of course, it is not limited to these, Two or more types can also be used together as needed.

  The content of the leuco dye is not particularly limited, but is preferably about 5 to 40% by mass with respect to the total solid content in the heat-sensitive recording layer.

  Examples of the colorant include 4,4′-isopropylidene diphenol, 4,4′-cyclohexylidene diphenol, 4-hydroxybenzoic acid benzyl ester, 4,4′-dihydroxydiphenyl sulfone, and 4-hydroxy-4. '-Allyloxydiphenylsulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone, 2,4'-dihydroxydiphenylsulfone, 3,3'-diallyl-4,4'-dihydroxydiphenylsulfone, 1,1-bis ( 4-hydroxyphenyl) -1-phenylethane, 1,4-bis [α-methyl-α- (4′-hydroxyphenyl) ethyl] benzene, 2,2 ′-[4- (4-hydroxyphenylsulfonyl) phenoxy ] Phenolic compounds such as diethyl ether, Np-tolylsulfonyl- N′-phenylurea, 4,4′-bis [(4-methyl-3-phenoxycarbonylaminophenyl) ureido] diphenylsulfone, 4,4′-bis (Np-tolylsulfonylaminocarbonylamino) diphenylmethane, N Compounds having a sulfonyl group and a ureido group in the molecule such as-(p-tolylsulfonyl) -N'-p-butoxyphenylurea, 4- [2- (p-methoxyphenoxy) ethyloxy] zinc salicylate, 4- [3 Examples include zinc salts of aromatic carboxylic acids such as zinc (p-tolylsulfonyl) propyloxy] salicylate and zinc 5- [p- (2- (p-methoxyphenoxyethoxy) cumyl] salicylate. It is not limited to these, and two or more kinds may be used in combination as required.

  The content of the colorant is not particularly limited, and may be appropriately selected according to the type of the leuco dye and the colorant to be used. Usually, about 1 to 10 parts by mass is preferable with respect to 1 part by mass of the leuco dye. More preferably, it is about 1 to 5 parts by mass.

The heat-sensitive recording layer is, for example, water as a medium, a leuco dye, a colorant, and, if necessary, various known preservability improvers and sensitizers, pigments, additives, etc., with an agitator / crusher such as a sand mill, attritor, or ball mill. A coating solution for a heat-sensitive recording layer prepared by mixing and stirring an adhesive and a dispersion obtained by finely pulverizing together or separately, the coating amount after drying is about 3 to 20 g / m ² Thus, a protective layer and a thermosensitive recording layer are applied and dried in this order on a substrate having a smooth surface in advance. Examples of the adhesive include an aqueous resin contained in the protective layer. The content of the adhesive is preferably about 8 to 35% by mass with respect to the total solid content in the heat-sensitive recording layer.

  The intermediate layer in the present invention contains a resin as a main component. Although it does not specifically limit as resin, For example, the substance which has adhesiveness, such as aqueous resin, a solventless type ultraviolet-ray, or an electron beam curable resin, is mentioned. In the present invention, from the viewpoint of good adhesion and excellent productivity, the intermediate layer contains an ultraviolet ray or an electron beam curable resin as a main component and is a layer cured by irradiating with an ultraviolet ray or an electron beam. Is preferred. In addition, as the resin, an ultraviolet ray or an electron beam curable resin can be contained in the form of an emulsion, but it is not necessary to dry after joining the support side and the substrate side having a smooth surface through an intermediate layer. From the viewpoint that synthetic paper or resin film having low moisture permeability can be used, a solventless ultraviolet or electron beam curable resin is more preferable. In addition, the main component in this invention is a main component in the component to comprise, and generally means containing about 30 mass% or more of the whole.

  Examples of the ultraviolet ray or electron beam curable resin include compounds such as (meth) acrylate monomers and oligomers having one or more ethylenically unsaturated bonds. Monofunctional monomers include N-vinylpyrrolidone, acrylonitrile or derivatives thereof, styrene or derivatives thereof, amide group-containing monomers such as acrylamide, benzyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl ( (Meth) acrylate, tetrahydrofurfuryl acrylate, phenoxyethyl acrylate, nonylphenoxyethyl acrylate, acrylate of caprolactone adduct, butoxyethyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl acrylate, cyclohexyl (meth) acrylate, N, N -Dimethylaminomethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, 3-phenoxypropylene Acrylate, 2-methoxyethyl (meth) acrylate of (meth) acrylate.

  Monomers having two or more ethylenically unsaturated bonds include hexanediol diacrylate, neopentyl glycol diacrylate, diethylene glycol diacrylate, tripropylene glycol diacrylate, tetraethylene glycol diacrylate, tricyclodecane dimethylol diacrylate, Examples include methylolpropane tetraacrylate, dipentaerythritol hexa (penta) acrylate, acrylate of ε-caprolactone-modified dipentaerythritol, ethylene oxide-modified bisphenol A diacrylate, and the like. These compounds having one or more ethylenically unsaturated bonds may be used alone or in combination of two or more.

  Examples of (meth) acrylate oligomers having one or more ethylenically unsaturated bonds include urethane (meth) acrylate oligomers, polyester (meth) acrylate oligomers, butadiene-modified (meth) acrylate oligomers, etc. And may be used.

  When the ultraviolet ray or the electron beam curable resin is cured by irradiating the ultraviolet ray, curing can be promoted by containing a photopolymerization initiator. The photopolymerization initiator is not limited and various known ones can be used. For example, methyl benzoylbenzoate, benzoin, benzyldimethyl ketal, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2-methyl-1- [4- (methylthio) phenyl] -2- Morpholino-1-propanone, 1-hydroxycyclohexyl phenyl ketone, 2,4-diethylthioxanthone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, camphorquinone , Anthracene, benzyl, phenylmethylglyoxylate and the like. Each of these photopolymerization initiators can be used alone or in combination of two or more.

  The content of the photopolymerization initiator is preferably about 0.05 to 10 parts by mass, more preferably about 0.1 to 5 parts by mass with respect to 100 parts by mass of the ultraviolet ray or electron beam curable resin. By setting the content to 0.05 parts by mass or more, curing can be effectively promoted. On the other hand, if it exceeds 10 parts by mass, the curability will be saturated, so the production cost can be reduced by setting it to 10 parts by mass or less.

  When ultraviolet rays are used, examples of the ultraviolet light source include 1 to 50 ultraviolet lamps, xenon lamps, tungsten lamps, and the like. Thereby, the ultraviolet-ray which has the intensity | strength of about 40-240 W / cm, Preferably about 60-180 W / cm can be irradiated. On the other hand, when an electron beam is used, the absorbed dose of the irradiated electron beam is preferably 150 kGy or less. More preferably, it is 100 kGy or less. Excessive irradiation exceeding 150 kGy may cause discoloration and strength reduction of the thermal recording medium. Although the minimum of the electron beam to irradiate is not limited, 10 kGy or more is preferable when obtaining a desired effect. More preferably, it is 20 kGy or more. The acceleration voltage upon irradiation is preferably about 30 to 300 kV, more preferably about 70 to 200 kV. As an electron beam irradiation method, a curtain beam method, a scanning method, a broad beam method, or the like can be used. The ultraviolet rays or the electron beam may be irradiated from either side of the support or the substrate having a smooth surface, and the irradiation conditions may be appropriately selected according to the type and the application amount of the ultraviolet ray or the electron beam curable resin. .

The intermediate layer is made of, for example, ultraviolet or electron beam curable resin, if necessary, photopolymerization initiator, pigment, additive, etc., three roll mill, two roll mill, cowless dissolver, homomixer, sand mill, paint conditioner and ultrasonic dispersion. the intermediate layer coating liquid obtained by mixing and stirring using a machine or the like, about the coating weight of 1 to 6 g / ^{m 2} after drying, and preferably 1.5 to 4.0 g / ^{m 2} approximately Thus, it is applied to at least one of the surface of the thermal recording layer provided on the one side of the support and the substrate side having a smooth surface, or the surface of a barrier layer described later if necessary, and uncured intermediate The surface of the substrate side having a smooth surface is bonded to the support side through the layer application surface, and cured by irradiating with ultraviolet rays or electron beams.

  In the present invention, a barrier layer containing an aqueous resin can be provided between the intermediate layer and the thermosensitive recording layer as necessary. Accordingly, it is possible to prevent the ultraviolet ray or the electron beam curable resin from penetrating into the heat-sensitive recording layer to cause background fogging, the recording sensitivity to be lowered, and the storability of the heat-sensitive recording layer to be lowered. As the aqueous resin, an aqueous resin having a barrier property is preferable, and examples thereof include an aqueous resin contained in the protective layer.

The barrier layer is, for example, a coating solution for a barrier layer prepared by mixing and stirring an aqueous resin and, if necessary, a surfactant such as sodium dioctylsulfosuccinate, using water as a medium, and the coating amount after drying is 0.5. to 5.0 g / ^{m 2,} preferably about so that 0.5 to 2.0 g / ^{m 2} approximately, protective layer on a substrate having a pre-smooth surface, heat-sensitive recording layer, coating and the order of the barrier layer It is formed by drying.

  Each of the above coating liquids may be applied and dried one layer at a time, or the same coating liquid may be applied in two or more layers. Two or more layers can be applied simultaneously. As a coating method, for example, a slot die, a slide bead, a curtain, an air knife, a blade, a Mayer bar, a rod, a roll coater, or the like is used.

  In the present invention, from the viewpoint of improving productivity, an embodiment in which at least a heat-sensitive recording layer and an adjacent protective layer are applied simultaneously is preferable. Cracks on the recording surface due to drying shrinkage are likely to occur in the process of simultaneous multi-layer coating and drying on a substrate having a smooth surface, but the protective layer adjacent to the heat-sensitive recording layer contains the specific PVA. The effect of can be demonstrated without regret. As a method for simultaneous multilayer coating, a bead coating method such as a slide die or a multilayer slot die or a curtain coating method such as a slide curtain is preferably used.

  In simultaneous multi-layer coating, even when the wet coating amount of each layer is small, a uniform coating surface can be obtained by applying the multi-layers in layers, and even better recording image quality can be obtained. . In particular, the protective layer and the barrier layer, which are the outermost layers, are effective with a small amount of application compared to the heat-sensitive recording layer. Obtainable. Furthermore, by increasing the solid content concentration of each coating liquid, it is possible to reduce the drying load and improve productivity.

  The thermal recording material of the present invention preferably has an image clarity (based on JIS K7105-1981) of an unrecorded portion of 75% (value at a slit width of 2 mm) or more. The image sharpness is one of the optical properties of the recording surface. The image sharpness is measured by measuring the light reflected by the sample through a moving optical comb and calculating it. By setting the image definition of the unrecorded portion to 75% or more, the recording image quality can be further improved. It is more preferable that the image definition is 80% or more.

  The image clarity of the unrecorded portion can be 75% or more by various methods. In the present invention, the protective layer adjacent to the heat-sensitive recording layer contains polyvinyl alcohol having a polymerization degree of 200 to 600. Since a uniform protective layer coating surface is formed and no cracks occur on the recording surface, the image definition can be improved.

  The heat-sensitive recording material of the present invention comprises an intermediate layer containing a resin as a main component on one surface of a support, a barrier layer provided as necessary, an electron-donating compound, and an electron-accepting compound. And a thermal recording material having a protective layer containing one or two or more aqueous resins in this order, wherein the protective layer adjacent to the thermal recording layer contains polyvinyl alcohol having a polymerization degree of 200 to 600, and is the outermost layer. The protective layer is a method for producing a thermal recording body having a surface transferred from a substrate having a smooth surface to a support, and becomes the outermost layer on the substrate having a smooth surface in advance. A protective layer having a protective layer disposed on the side closest to the substrate, a heat-sensitive recording layer, and if necessary, a barrier layer are provided in this order, and one side of the support and the heat-sensitive recording layer or barrier layer are provided via an intermediate layer. Bonding surfaces, smooth surface It is produced by a method characterized by peeling between the protective layer of the surface and the outermost layer of the substrate having.

  The heat-sensitive recording material of the present invention is more preferably a protective layer in which a protective layer serving as the outermost layer is disposed on the side closest to the base material on a base material having a smooth surface in advance, and if necessary. Barrier layers are provided in this order, and one surface of the support is bonded to the surface of the thermosensitive recording layer or barrier layer via an uncured intermediate layer containing ultraviolet rays or an electron beam curable resin as a main component. It is manufactured by a method of irradiating an electron beam to cure the intermediate layer and peeling between the surface of the substrate having a smooth surface and the protective layer as the outermost layer.

  A method for joining one surface of the support to the heat-sensitive recording layer or the barrier layer through the intermediate layer is not particularly limited, but it is preferable that the surface is brought into close contact with a pressure nip composed of a metal roll and an elastic roll. . At that time, it is preferable that the support side is in contact with the metal roll surface, and the base material side having a smooth surface is in contact with the elastic roll surface. As a result, the adhesive substance exhibits a more excellent anchoring effect, and it is easy to peel off the surface of the substrate having a smooth surface and the protective layer that is the outermost layer, and has a high glossiness. A record can be obtained.

  Examples of the surface material of the elastic roll used in the present invention include urethane rubber, nitrile rubber (NBR), chloroprene rubber (CR), styrene / butadiene rubber (SBR), ethylene / propylene rubber (EPDM) and the like. In addition, by finishing the surface of the elastic roll to a desired surface roughness, air entrainment during nip can be suppressed and a more uniform intermediate layer can be provided. The surface roughness of the elastic roll is not particularly limited, but is preferably Rmax 10 μm or less (according to JIS B0601).

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, it is not limited to these. Unless otherwise specified, “part” and “%” represent “part by mass” and “% by mass”, respectively. The average particle size was measured using a laser diffraction particle size distribution analyzer SALD2000 (manufactured by Shimadzu Corporation).

Example 1
Preparation of leuco dye dispersion (liquid A) Composition comprising 20 parts of 3-di (n-butyl) amino-6-methyl-7-anilinofluorane, 10 parts of a 10% aqueous solution of polyvinyl alcohol, and 20 parts of water. The product was dispersed with a sand mill so that the average particle size was 1.0 μm to obtain liquid A.

-Preparation of colorant dispersion (liquid B) A composition consisting of 50 parts of 4-hydroxy-4'-isopropoxydiphenylsulfone, 20 parts of a 10% aqueous solution of polyvinyl alcohol, and 60 parts of water was averaged in a sand mill. Liquid B was obtained by dispersing to 1.2 μm.

-Preparation of coating solution for heat-sensitive recording layer A part 70 parts, B part 75 parts, silica (trade name: Nipseal E-743, manufactured by Nippon Silica Co.) 25% slurry 40 parts, polyvinyl alcohol 10% aqueous solution 50 parts, 30 parts of styrene / butadiene latex (trade name: L-1571, solid concentration 48%, manufactured by Asahi Kasei), stearamide (trade name: Hi-micron L-271, solid concentration 25%, manufactured by Chukyo Yushi Co., Ltd.) 20 parts, a composition comprising 2 parts of a 10% aqueous solution of a fluorosurfactant (trade name: Megafac F-445, manufactured by Dainippon Ink & Chemicals, Inc.) and 35 parts of water are mixed and stirred for a heat-sensitive recording layer. A coating solution was obtained.

-Preparation of coating solution for first protective layer 70 parts of 60% slurry of kaolin (trade name: UW-90, manufactured by Engelhard), zinc stearate (trade name: hydrin Z-8-36, solid content 36%, 13 parts by Chukyo Yushi Co., Ltd., 210 parts of 10% aqueous solution of acetoacetyl-modified polyvinyl alcohol (trade name: Gohsephimer Z-100, polymerization degree 500, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), 10% of dioctylsulfosuccinate sodium salt A composition comprising 2 parts of an aqueous solution and 120 parts of water was mixed and stirred to obtain a first protective layer coating solution.

-Preparation of coating liquid for second protective layer Acrylic latex (trade name: Barrier Star B-4050, solid content concentration 20%, manufactured by Mitsui Chemicals) 120 parts, kaolin (trade name: UW-90, manufactured by Engelhard) ) 60 parts slurry, stearyl phosphate potassium salt (trade name: Wopol 1800, solid concentration 35%, manufactured by Matsumoto Yushi Seiyaku Co., Ltd.), 5 parts dioctyl sulfosuccinate sodium salt 5 parts aqueous solution, and water A composition comprising 150 parts was mixed and stirred to obtain a second protective layer coating solution.

-Preparation of coating solution for intermediate layer 80 parts of acrylate of ε-caprolactone-modified dipentaerythritol (trade name: Kayrad DPCA-60, manufactured by Nippon Kayaku Co., Ltd.) as an electron beam curable resin and 1,6-hexane modified with ethylene oxide 20 parts of diol diacrylate (trade name: Kayarad R-167, manufactured by Nippon Kayaku Co., Ltd.) was mixed and stirred with a cowless dissolver to obtain an intermediate layer coating solution.

-Preparation of thermosensitive recording material A coating liquid for the second protective layer on a PET (polyethylene terephthalate) film (trade name: Teijin Tetron Film S, thickness 25 μm, manufactured by Teijin DuPont Films Ltd.) as a substrate having a smooth surface the first protective layer coating solution, a thermal recording layer coating solution in this order, so that the coating amount after drying of ^{each, 0.5g / m 2, 3.0g /} m 2, and 7.0 g / ^{m 2} In addition, simultaneous multilayer coating and drying were performed using a slide die. On the other hand, the coating amount after curing the intermediate layer coating solution on one surface of a synthetic paper (trade name: YUPO FPG-80, manufactured by YUPO Corporation) as a support is 3.0 g / m ^2. The surface of the heat-sensitive recording layer is bonded to one surface of the support through the intermediate layer coating surface, and an acceleration voltage of 175 kV is applied from the support by an electrocurtain type electron beam accelerator (manufactured by ESI). The intermediate layer was cured by irradiating an electron beam with an absorbed dose of 35 kGy, and then the surface of the PET film and the protective layer serving as the outermost layer were peeled to obtain a heat-sensitive recording material.

Example 2
Example 1 was used except that partially saponified polyvinyl alcohol (trade name: PVA203, polymerization degree 300, manufactured by Kuraray Co., Ltd.) was used instead of the polyvinyl alcohol used for the preparation of the first protective layer coating solution of Example 1. A heat-sensitive recording material was obtained in the same manner.

Example 3
In the production of the heat-sensitive recording material of Example 1, the coating amount for the first protective layer and the heat-sensitive recording layer coating solution in this order on the PET (polyethylene terephthalate) film were 3.5 g / m after drying, respectively. ^A thermal recording material was obtained in the same manner as in Example 1 except that simultaneous multi-layer coating and drying were performed using a slide die so as to be ² and 7.0 g / m ² .

Comparative Example 1
Instead of the polyvinyl alcohol used in the preparation of the first protective layer coating solution of Example 1, acetoacetyl-modified polyvinyl alcohol (trade name: Gohsephimer Z-200, polymerization degree 1000, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) A thermosensitive recording material was obtained in the same manner as in Example 1 except that it was used.

Comparative Example 2
In place of the polyvinyl alcohol used for the preparation of the first protective layer coating liquid of Example 1, carboxy-modified polyvinyl alcohol (trade name: Gohsenal T215, polymerization degree 1200, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) was used. A heat-sensitive recording material was obtained in the same manner as in Example 1.

Comparative Example 3
Example 1 was used except that partially saponified polyvinyl alcohol (trade name: PVA217, degree of polymerization 1700, manufactured by Kuraray Co., Ltd.) was used instead of the polyvinyl alcohol used in the preparation of the first protective layer coating solution of Example 1. A heat-sensitive recording material was obtained in the same manner.

  The thermosensitive recording material thus obtained was evaluated as follows. The results are shown in Table 1.

[Glossiness]
The 75 degree glossiness was measured with a gloss meter (trade name: GM-26D, Murakami Color Research Laboratory).

[Recording density]
The 17 gradations of the built-in pattern were recorded with a thermal recording printer (trade name: UP-880, manufactured by Sony Corporation), and the gradation density was measured with a Macbeth densitometer (trade name: RD918, manufactured by Gretag Macbeth Co.).

[Recording quality]
A halftone of the built-in pattern was recorded with a thermal recording printer (trade name: UP-880, manufactured by Sony Corporation), and the image quality was visually evaluated.
A: The recorded image is very uniform.
○: The recorded image is uniform.
Δ: The recorded image is not uniform.
X: The recorded image is very uneven.

[Crack of recording surface]
The degree of cracking on the recording surface (unrecorded portion) of the thermal recording material was visually evaluated with a loupe.
A: There is no crack at all.
○: There are some cracks.
Δ: There are many cracks.
X: There are many cracks.

Claims (6)

  On one side of the support, an intermediate layer containing a resin as a main component, a barrier layer containing an aqueous resin provided as necessary, a thermosensitive recording layer containing an electron donating compound and an electron accepting compound, and 1 A heat-sensitive recording material having a layer or a protective layer containing two or more aqueous resins in this order, and at least the protective layer adjacent to the heat-sensitive recording layer contains polyvinyl alcohol having a polymerization degree of 200 to 600 and becomes the outermost layer. A heat-sensitive recording material, wherein the protective layer has a surface transferred from a substrate having a smooth surface to a support.   2. The heat-sensitive recording material according to claim 1, wherein the intermediate layer contains an ultraviolet ray or an electron beam curable resin as a main component and is cured by irradiation with an ultraviolet ray or an electron beam.   The support is either synthetic paper, a resin film or a laminate of resin film and paper, and the substrate having a smooth surface is either a resin film, a mirror-plated metal drum or an endless belt. Item 3. The thermal recording material according to item 1 or 2.   On one side of the support, an intermediate layer containing a resin as a main component, a barrier layer containing an aqueous resin provided as necessary, a thermosensitive recording layer containing an electron donating compound and an electron accepting compound, and 1 A heat-sensitive recording material having a layer or a protective layer containing two or more aqueous resins in this order, and at least the protective layer adjacent to the heat-sensitive recording layer contains polyvinyl alcohol having a polymerization degree of 200 to 600 and becomes the outermost layer. A method for producing a thermal recording medium having a surface transferred from a substrate having a smooth surface to a support, the protective layer serving as the outermost layer on a substrate having a smooth surface in advance A protective layer, the thermal recording layer, and a barrier layer as necessary are arranged in this order on the side closest to the substrate, and one surface of the support is bonded to the surface of the thermal recording layer or barrier layer via an intermediate layer. Smooth Method for producing a thermosensitive recording material, characterized in that peeling between the protective layer of the surface and the outermost layer of the substrate having a surface.   A protective layer in which a protective layer that is the outermost layer is disposed on the side closest to the substrate, a heat-sensitive recording layer, and a barrier layer as necessary are provided in this order on a substrate having a smooth surface in advance, and UV or electron beam curing Bonding one side of the support and the surface of the heat-sensitive recording layer or barrier layer through an uncured intermediate layer containing a functional resin as a main component, curing the intermediate layer by irradiating with ultraviolet rays or electron beams, The method for producing a heat-sensitive recording material according to claim 4, wherein the surface of the substrate having a smooth surface and the protective layer which is the outermost layer are peeled off.   6. The method for producing a heat-sensitive recording material according to claim 4, wherein at least a heat-sensitive recording layer and an adjacent protective layer are simultaneously applied and provided on a substrate having a smooth surface.