Thermal recording device

Abstract

To provide a thermal recording medium with excellent light resistance and storage properties. [Solution] The thermal recording body 1 of the present invention has a laminated structure in which a thermal recording layer 4, an intermediate layer 5, and an ultraviolet absorbing layer 6 are laminated in this order on a substrate 2. The thermal recording layer 4 contains a dye and a developer. The developer contains a compound represented by a specific structure. The ultraviolet absorbing layer 6 contains an ultraviolet absorber. The ultraviolet absorber contains a benzotriazole-based ultraviolet absorber and / or a hydroxyphenyltriazine-based ultraviolet absorber.

Description

Technical Field

[0001] The present invention relates to a heat-sensitive recording medium.

Background Art

[0002] A heat-sensitive recording medium develops color by a chemical reaction upon heating by a thermal head or the like, and a recorded image can be obtained. It is not only used as a recording medium for facsimiles, automatic ticket vending machines, and scientific measuring instruments, but also widely used as a heat-sensitive recording label for POS systems in retail stores and the like, receipt paper, and the like.

[0003] Since the heat-sensitive recording medium is widely used as described above, various performances are required. For example, the heat-sensitive recording medium may be exposed to various lights such as being used outdoors and exposed to sunlight or being used indoors and exposed to fluorescent lights. When the heat-sensitive recording medium is thus exposed to light, a coloring problem such as yellowing of its background (non-printed part) may occur, which may impair visibility and aesthetics. Therefore, the heat-sensitive recording medium is required to have a performance capable of suppressing coloring even when exposed to light, that is, light resistance.

[0004] As a technique for improving light resistance, a technique of providing an ultraviolet absorption layer containing an ultraviolet absorber on the heat-sensitive recording layer is known. For example, a heat-sensitive recording medium in which a heat-sensitive recording layer and an ultraviolet absorption layer are laminated in this order on a support has been proposed (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Furthermore, thermal recording media are required to have the ability to maintain the printed area for a long period of time, i.e., to have good preservation properties. However, the printed area of ​​thermal recording media can disappear due to various factors, and there are many unknowns regarding how the addition of an ultraviolet absorption layer will affect preservation properties. Given these circumstances, there is a demand for thermal recording media that excel in both light resistance and preservation properties.

[0007] Therefore, the object of the present invention is to provide a thermal recording material that is excellent in light resistance and storage properties. [Means for solving the problem]

[0008] As a result of diligent research to achieve the above objective, the inventors have found that by including a specific color developer in the thermal recording layer, a specific ultraviolet absorber in the ultraviolet absorption layer, and providing an intermediate layer between the thermal recording layer and the ultraviolet absorption layer, it is possible to provide a thermal recording material with excellent light resistance and storage properties. The present invention was completed based on these findings.

[0009] In other words, the present invention provides a thermal recording body in which a thermal recording layer, an intermediate layer, and an ultraviolet absorbing layer are laminated in this order on a substrate. The thermal recording layer contains a dye and a developer, and the ultraviolet absorbing layer contains an ultraviolet absorber. Furthermore, the developer contains a compound represented by the following formula (1) and / or a compound represented by the following formula (2), and the ultraviolet absorber contains a benzotriazole-based ultraviolet absorber and / or a hydroxyphenyltriazine-based ultraviolet absorber.

[0010] [ka]

[0011] In formula (1), R 1 is a hydrocarbon group having 1 to 12 carbon atoms, which may have substituents, and multiple R 1 They may be the same or different. 1 It is a hydrocarbon group having 1 to 4 carbon atoms, and multiple A 1The values ​​of p may be the same or different. p represents an integer between 0 and 4, and multiple p values ​​may be the same or different.

[0012] [ka]

[0013] In formula (2), A 2 It is a hydrocarbon group having 1 to 4 carbon atoms, and multiple A 2 The integers q and r can be the same or different. q represents an integer between 0 and 4, and multiple qs can be the same or different. r represents an integer between 1 and 11.

[0014] The compound represented by formula (1) above preferably includes the compound represented by formula (1a) below.

[0015] [ka]

[0016] The above-mentioned color developer preferably contains at least the compound represented by formula (1a) above.

[0017] The compound represented by formula (2) above is preferably the compound represented by formula (2a) below.

[0018] [ka]

[0019] In equation (2a), s represents an integer from 1 to 7.

[0020] The above-mentioned color developer preferably contains at least the compound represented by formula (2a) above.

[0021] The content ratio of the above-mentioned ultraviolet absorber is preferably 1% to 30% by mass based on 100% by mass of the total solid content of the above-mentioned ultraviolet absorber layer.

[0022] The above-mentioned intermediate layer preferably has a cross-linked structure.

[0023] The above crosslinking structure preferably includes a crosslinking structure derived from a carboxyl group and an azetidinium group.

[0024] The above-mentioned thermal recording material preferably includes an undercoat layer between the substrate and the thermal recording layer. [Effects of the Invention]

[0025] According to the present invention, it is possible to provide a thermal recording material that is excellent in light resistance and storage. [Brief explanation of the drawing]

[0026] [Figure 1] This is a schematic cross-sectional view showing one embodiment of the thermal recording body of the present invention. [Figure 2] This is a schematic cross-sectional view showing another embodiment of the thermal recording body of the present invention. [Modes for carrying out the invention]

[0027] [Thermal recording media] The thermal recording material of the present invention comprises, on a substrate, at least a thermal recording layer, an intermediate layer, and an ultraviolet absorbing layer laminated in this order. The thermal recording layer contains a dye and a developer, and the developer contains a compound represented by the following formula (1) and / or a compound represented by the following formula (2). Furthermore, the ultraviolet absorbing layer contains an ultraviolet absorber, and the ultraviolet absorber contains a benzotriazole-based ultraviolet absorber and / or a hydroxyphenyltriazine-based ultraviolet absorber.

[0028] [ka]

[0029] In formula (1), R 1 is a hydrocarbon group having 1 to 12 carbon atoms, which may have substituents, and multiple R 1may be the same or different. A 1 is a hydrocarbon group having 1 to 4 carbon atoms, and a plurality of A 1 may be the same or different. p represents an integer of 0 to 4, and a plurality of p may be the same or different.

[0030] [Chemical formula]

[0031] In formula (2), A 2 is a hydrocarbon group having 1 to 4 carbon atoms, and a plurality of A 2 may be the same or different. q represents an integer of 0 to 4, and a plurality of q may be the same or different. r represents an integer of 1 to 11.

[0032] Hereinafter, an embodiment of the heat-sensitive recording medium of the present invention will be described in detail based on the drawings, but the present invention is not limited to the following embodiments.

[0033] FIG. 1 is a schematic cross-sectional view showing an embodiment of the heat-sensitive recording medium of the present invention. In FIG. 1, the heat-sensitive recording medium 1 includes a sheet-like base material 2, a heat-sensitive recording layer 4, an intermediate layer 5, and an ultraviolet absorption layer 6 in this order. At this time, the heat-sensitive recording layer 4 is laminated so as to directly contact the surface of the base material 2, the intermediate layer 5 is laminated so as to directly contact the surface of the heat-sensitive recording layer 4, and the ultraviolet absorption layer 6 is laminated so as to directly contact the surface of the intermediate layer 5.

[0034] FIG. 2 is a schematic cross-sectional view showing another embodiment of the heat-sensitive recording medium of the present invention. In FIG. 2, the heat-sensitive recording medium 1 has a laminated structure further including an undercoat layer 3 between the base material and the heat-sensitive recording layer 4. Specifically, the heat-sensitive recording medium 1 includes a sheet-like base material 2, an undercoat layer 3, a heat-sensitive recording layer 4, an intermediate layer 5, and an ultraviolet absorption layer 6 in this order. At this time, the undercoat layer 3 is laminated so as to directly contact the surface of the base material 2, and the heat-sensitive recording layer 4 is laminated so as to directly contact the surface of the undercoat layer 3.

[0035] Furthermore, the thermal recording body of the present invention may further comprise other layers. Examples of these other layers include, for example, other protective layers when the intermediate layer or the ultraviolet absorbing layer is used as a protective layer, a back coat layer, and the like. The other protective layer is a layer provided at any position on the surface of the thermal recording layer 4 opposite to the surface on which the substrate 2 is provided. That is, the other protective layer may be formed between the thermal recording layer 4 and the intermediate layer 5, or between the intermediate layer 5 and the ultraviolet absorbing layer 6, or on the surface of the ultraviolet absorbing layer 6 opposite to the surface on which the intermediate layer 5 is provided. The other protective layer may be a single layer or a multi-layer layer. The back coat layer is a layer provided on the surface of the substrate 2 opposite to the surface on which the thermal recording layer 4 is provided.

[0036] (base material) The base material 2 can function as a support in the thermal recording body 1 of the present invention. The thermal recording body 1 is superior in handling and other aspects by having the base material 2. As the base material 2, for example, paper such as fine paper, art paper, coated paper, kraft paper, laminated paper obtained by laminating these paper base materials with a thermoplastic resin such as polyethylene, porous materials such as nonwoven fabric, synthetic resin film, and synthetic paper can be used. Examples of resins constituting the above synthetic resin film and synthetic paper include polypropylene, polyethylene, polyethylene terephthalate, polystyrene, and polycarbonate. Only one of the above resins may be used, or two or more may be used. The above synthetic resin film may be stretched or not. Furthermore, the base material 2 may be a single layer or a multi-layer structure with the same composition or different thicknesses.

[0037] The thickness of the substrate 2 is not particularly limited, but is preferably 5 μm to 150 μm, and more preferably 10 μm to 100 μm. When the thickness is within the above range, it is easier to achieve more appropriate coating properties and support properties, and handling properties may be better.

[0038] (Undercoat layer) The undercoat layer 3 is a layer intended to improve heat insulation and cushioning properties to prevent heat dissipation from the thermal head, or to improve adhesion between the substrate 2 and the thermal recording layer 4. The undercoat layer 3 may be omitted if not required, in which case the thermal recording layer 4 can be directly laminated on one side of the substrate 2. The material used to form the undercoat layer 3 is not particularly limited and can be formed using, for example, a binder such as resin. The undercoat layer 3 may also contain other components. Examples of these other components include fillers, wetting agents, and preservatives.

[0039] Examples of the above resins include acrylic resins such as acrylic resin, styrene-acrylic resin, acrylic-urethane resin, acrylamide resin, and vinyl acetate-acrylic resin; maleic acid resins such as maleic acid resin, styrene-maleic acid resin, and olefin-maleic acid resin; styrene-butadiene rubber (SBR); and polyvinyl alcohol resins such as fully saponified polyvinyl alcohol resin and partially saponified polyvinyl alcohol resin. These resins may also be modified resins obtained by known methods. Furthermore, these resins can be used individually or in combination of two or more types.

[0040] In this specification, "acrylic resin" means a resin obtained by polymerizing acrylic monomers (acrylic resin), and / or a resin obtained by copolymerizing acrylic monomers with other monomers (monomers other than acrylic monomers that can copolymerize with acrylic monomers). Here, the other monomers may be two or more types. Also, when simply referred to as "acrylic," unless otherwise specified, it means (meth)acrylic acid (salt) and / or (meth)acrylic acid ester. Here, "(meth)acrylic acid" means acrylic acid and / or methacrylic acid, and "(meth)acrylic acid (salt)" means (meth)acrylic acid and / or (meth)acrylic acid salt.

[0041] The salts in the above-mentioned (meth)acrylate salts are not particularly limited and include, for example, ammonium salts such as ammonia; alkanolamine salts such as triethanolamine, diethanolamine, and monoethanolamine; alkylamine salts such as methylamine, ethylamine, diethylamine, and triethylamine; polyamine salts such as diethyleneamine and diethylenetriamine; alkali metal salts such as lithium, sodium, and potassium; alkaline earth metal salts such as magnesium and calcium; and polyvalent metal salts such as zinc and iron. These salts can be used individually or in combination of two or more.

[0042] The composition forming the above resin may be a solid, an emulsion, or a solution. From the viewpoint of excellent handling and coating properties, an emulsion or a solution is preferred.

[0043] Examples of the above-mentioned fillers include inorganic fillers such as kaolin, calcined kaolin, aluminum oxide, aluminum silicate, heavy calcium carbonate, light calcium carbonate, titanium dioxide, barium sulfate, silica gel, activated clay, talc, clay, kaolinite, diatomaceous earth, white carbon, magnesium carbonate, magnesium oxide, magnesium hydroxide, aluminum hydroxide, and zinc oxide; and organic fillers such as hollow particles and non-hollow particles. From the viewpoint of improving heat insulation and cushioning properties, it is preferable that the above-mentioned fillers include hollow particles. These fillers can be used individually or in combination of two or more types.

[0044] The materials constituting the hollow and non-hollow particles are not particularly limited, and examples include thermoplastic resins. Examples of thermoplastic resins include acrylic resins such as acrylic resin, acrylonitrile resin, acrylic-polyvinylidene chloride resin, acrylic-polyvinylidene chloride-acrylonitrile resin, acrylic-acrylonitrile resin, styrene-acrylic resin, acrylic-urethane resin, acrylamide resin, and vinyl acetate-acrylic resin; polyvinylidene chloride resins such as polyvinylidene chloride resin and polyvinylidene chloride-acrylonitrile resin; polystyrene resins; urea-formaldehyde resins; polyolefin resins such as polyethylene resin and polypropylene resin; polyvinyl chloride resins; polyvinyl acetate resins; and polybutadiene resins. Furthermore, these resins may be modified resins obtained by known methods.

[0045] The average particle diameter of the hollow particles is not particularly limited, but is preferably 0.5 μm or more, more preferably 1 μm or more, even more preferably 3 μm or more, and especially preferably 5 μm or more. Alternatively, the average particle diameter may be 100 μm or less, more preferably 50 μm or less, and even more preferably 30 μm or less. When the average particle diameter is within the above range, it is easier to achieve better thermal insulation, and heat resistance and print density can be improved. In this specification, "average particle diameter" refers to the particle diameter (D50, median diameter) at 50% of the cumulative value of the particle size distribution measured by laser diffraction and scattering. The average particle diameter can be measured by laser diffraction and scattering, for example, using the "MT3300EX-II" product name from Microtrac-Bell. Hereinafter, "average particle diameter" refers to the median diameter measured by the above method.

[0046] Examples of the above-mentioned wetting agents include surfactants. Known surfactants can be used as appropriate, including, for example, anionic surfactants such as sodium dioctyol succinate, sodium dodecylbenzenesulfonate, sodium lauryl sulfate, and alkyl ether sulfates; and nonionic surfactants such as acetylene glycol-based surfactants and polyoxyalkylene alkyl ethers. Among these, acetylene glycol-based surfactants such as acetylene glycol and alkylene oxide adducts of acetylene glycol are preferred. These wetting agents can be used individually or in combination of two or more.

[0047] The coating amount (dry mass) of the above undercoat layer 3 is preferably, for example, 0.3 g / m². 2 ~10g / m 2 And more preferably 0.5 g / m 2 ~5.0g / m 2 Therefore, when the amount of coating is within the above range, it is easier to achieve more appropriate properties such as heat insulation, cushioning, and adhesion between the substrate 2 and the heat-sensitive recording layer 4. In this specification, "dry mass" refers to the mass of non-volatile components (solids) excluding solvents (volatile components) such as water contained in the coating liquid or its raw materials.

[0048] (Thermal recording layer) The thermal recording layer 4 is a layer that develops color through a chemical reaction upon heating by a thermal head or the like, forming a recorded image on the thermal recording body 1. The thermal recording layer 4 contains at least a dye and a color developer. The thermal recording layer 4 may further contain other components as needed. Examples of these other components include binders, fillers, lubricants, wetting agents, sensitizers, crosslinking agents, and preservatives.

[0049] Examples of the above dyes include 3-dibutylamino-6-methyl-7-anilinofluorolane, 2-aniline-3methyl-6-(N-methyl-p-toluidino)fluorane, 3-(N-isobutyl-N-ethyl)amino-6-methyl-7-anilinofluorane, 3-(N-isopentyl-N-ethyl)amino-6-methyl-7-o-chloroanilinofluorane, and 3-(N-methyl-Np-toluidino)-6-methyl-7-anilinofluorane. Linofluoran, 3-(N-ethyl-Np-toluidino)-6-methyl-7-anilinofluoran, 3-(N-ethyl-N-isopentyl)amino-6-methyl-7-anilinofluoran, 3-(N-ethoxypropyl-N-ethyl)amino-6-methyl-7-anilinofluoran, 3-(N-cyclohexyl-N-methyl)amino-6-methyl-7-anilinofluoran, 3-(N-methyl-Nn-propyl)amino-6- Methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-p-toluidinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-8-methylfluorane, 3-diethylamino-7-(m-trifluoromethylanilino)fluorane, 3-diethylamino-7-(o-chloroanilino)fluorane Oran, 3-diethylamino-7-chlorofluoran, 3-dibutylamino-6-methyl-7-bromofluoran, 3-dibutylamino-7-(o-chloroanilino)fluoran, 3-dipentylamino-6-methyl-7-anilinofluoran, 3-dimethylamino-5-methyl-7-methylfluoran, 3-pyrrolidino-6-methyl-7-anilinofluoran, crystal violet lactone, etc. can be used. These dyes can be used individually or in combination of two or more.

[0050] The average particle size of the above dye is preferably 0.1 to 1.0 μm. Generally, dyes react by melting, so reducing the average particle size tends to improve sensitivity characteristics. On the other hand, increasing the average particle size tends to suppress unexpected color development due to heat during drying. When the average particle size is within the above range, the sensitivity characteristics and color development temperature of the dye can be adjusted more appropriately.

[0051] The content of the above dye is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, based on 100% by mass of the total solid content of the thermal recording layer 4. Furthermore, the content of the above dye is preferably 45% by mass or less, more preferably 40% by mass or less, and even more preferably 35% by mass or less, based on 100% by mass of the total solid content of the thermal recording layer 4.

[0052] The above-mentioned color developer contains at least a compound represented by formula (1) and / or a compound represented by formula (2). By including these color developers, good preservation properties such as oil resistance, plasticizer resistance, and alcohol resistance can be maintained even in a configuration that includes an ultraviolet absorption layer. Furthermore, from an environmental standpoint, it is preferable that the above-mentioned color developer contains a non-phenolic color developer such as the compound represented by formula (1). These color developers can be used individually or in combination of two or more.

[0053] In the above equation (1), R 1 is a hydrocarbon group having 1 to 12 carbon atoms, which may have substituents, and multiple R 1 They may be the same or different. 1 It is a hydrocarbon group having 1 to 4 carbon atoms, and multiple A 1 The values ​​of p may be the same or different. p represents an integer between 0 and 4, and multiple p values ​​may be the same or different.

[0054] In the above equation (1), multiple R 1 -SO3- is directly bonded to the carbon atoms that make up the benzene ring. Multiple R 1The substitution site of -SO3- is R on one of the benzene rings. 1 The substitution position of -SO3- and the R in the other benzene ring 1 The substitution positions of -SO3- may be the same or different from each other. R on one of the benzene rings 1 -SO3- substitution site and R on the other benzene ring 1 The substitution positions of the -SO3- groups are preferably the same, and more preferably both are at position 3. In this specification, in formula (1) above, the carbon atom on the benzene ring bonded to the nitrogen atom of the urea group (-NH-CO-NH-) is defined as position 1.

[0055] In the above formula (1), the above R 1 Among the "carbon groups having 1 to 12 carbon atoms that may have substituents," examples of "carbon groups having 1 to 12 carbon atoms" include linear alkyl groups having 1 to 12 carbon atoms, branched alkyl groups having 1 to 12 carbon atoms, alicyclic alkyl groups having 3 to 12 carbon atoms, aryl groups having 6 to 12 carbon atoms, or monovalent groups having 4 to 12 carbon atoms formed by bonding two or more different groups from these groups. Furthermore, multiple "carbon groups having 1 to 12 carbon atoms that may have substituents" may be the same or different from each other. Note that in this specification, the above R 1 In the phrase "carbon hydrocarbon groups having 1 to 12 carbon atoms," the number of carbon atoms refers to the total number of carbon atoms, including the carbon atoms in the substituents if they contain carbon atoms. Similarly, in the phrase "monovalent groups having 4 to 12 carbon atoms formed by the bonding of two or more distinct groups from these groups," the number of carbon atoms refers to the total number of carbon atoms, including the carbon atoms in the substituents if they contain carbon atoms.

[0056] The above-mentioned "linear alkyl group having 1 to 12 carbon atoms" may be a linear saturated alkyl group or a linear unsaturated alkyl group. Examples of the above-mentioned "linear alkyl group having 1 to 12 carbon atoms" include a methyl group, an ethyl group, an n-propyl group, an allyl group, an n-butyl group, a 3-butenyl group, an n-hexyl group, a lauryl group, and the like.

[0057] The above-mentioned "branched alkyl group having 3 to 12 carbon atoms" may be a branched saturated alkyl group or a branched unsaturated alkyl group. Examples of the above-mentioned "branched alkyl group having 3 to 12 carbon atoms" include i-propyl group, i-butyl group, s-butyl group, t-butyl group, and 2-ethylhexyl group.

[0058] The above-mentioned "alicyclic alkyl group having 3 to 12 carbon atoms" may be either an alicyclic saturated alkyl group or an alicyclic unsaturated alkyl group. Examples of the above-mentioned "alicyclic alkyl group having 3 to 12 carbon atoms" include a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, and the like.

[0059] Examples of the above-mentioned "aryl groups having 6 to 12 carbon atoms" include unsubstituted aryl groups such as phenyl, 1-naphthyl, and 2-naphthyl groups.

[0060] Examples of the above-mentioned "monovalent groups having 4 to 12 carbon atoms, formed by the bonding of two or more distinct groups" include "monovalent groups having 7 to 12 carbon atoms, formed by the bonding of an aryl group with one or more linear alkyl groups," "monovalent groups having 9 to 12 carbon atoms, formed by the bonding of an aryl group with one or more branched alkyl groups," and "monovalent groups having 4 to 12 carbon atoms, formed by the bonding of an alicyclic alkyl group with one or more linear alkyl groups."

[0061] The above-mentioned "monovalent group having 7 to 12 carbon atoms bonded to an aryl group and one or more linear alkyl groups" is preferably "a monovalent group having 7 to 12 carbon atoms bonded to a phenyl group and one to three linear alkyl groups having 1 to 4 carbon atoms." Specifically, examples include p-tolyl group, m-tolyl group, o-tolyl group, 2,5-dimethylphenyl group, 2,4-dimethylphenyl group, 3,5-dimethylphenyl group, 2,3-dimethylphenyl group, 3,4-dimethylphenyl group, mesitylene group, p-ethylphenyl group, etc. Alternatively, aralkyl groups such as benzyl group, 1-phenylethyl group, 2-phenylethyl group, 3-phenylpropyl group, p-methylbenzyl group, m-methylbenzyl group, m-ethylbenzyl group, and p-ethylbenzyl group may also be used. Furthermore, the above-mentioned "monovalent group having 7 to 12 carbon atoms, formed by bonding a phenyl group to 1 to 3 linear alkyl groups having 1 to 4 carbon atoms" may have substituents as described below.

[0062] The above-mentioned "monovalent group having 9 to 12 carbon atoms bonded to an aryl group and one or more branched alkyl groups" is preferably a "monovalent group having 7 to 12 carbon atoms bonded to a phenyl group and one or two branched alkyl groups having 3 to 4 carbon atoms." Specifically, examples include pi-propylphenyl group and pt-butylphenyl group. Furthermore, the above-mentioned "monovalent group having 7 to 12 carbon atoms bonded to a phenyl group and one or two branched alkyl groups having 3 to 4 carbon atoms" may have substituents as described later.

[0063] The above-mentioned "monovalent group having 4 to 12 carbon atoms bonded to an alicyclic alkyl group and one or more linear alkyl groups" is preferably a "monovalent group having 7 to 12 carbon atoms bonded to an alicyclic alkyl group having 6 to 12 carbon atoms and one to three linear alkyl groups having 1 to 4 carbon atoms." Specifically, examples include the 4-methylcyclohexyl group and the 4-methylcyclooctyl group. Furthermore, the above-mentioned "monovalent group having 7 to 12 carbon atoms bonded to an alicyclic alkyl group having 6 to 12 carbon atoms and one to three linear alkyl groups having 1 to 4 carbon atoms" may have substituents as described later.

[0064] The above-mentioned "substituent" is a group having at least one atom other than a carbon atom (heteroatom). In this specification, the heteroatom in the "substituent" is assumed to be bonded to a carbon atom in the "carbon 1 to 12 hydrocarbon group". Specifically, examples of the above-mentioned "substituent" include halogen atoms, hydroxyl groups, alkoxy groups, oxo groups (=O), etc. Furthermore, the above-mentioned "substituent" may or may not contain a carbon atom. If the above-mentioned "substituent" contains a carbon atom, the number of carbon atoms in the substituent is preferably 1 to 6, and more preferably 1 to 4. There may or may not be multiple above-mentioned "substituents". Furthermore, the substitution position of multiple "substituents" is on one of the benzene rings R 1 and R on the other benzene ring 1 The R on one of the benzene rings may be the same or different from each other. 1 The substitution position of the substituent in and the R on the other benzene ring 1 It is preferable that the substitution positions of the substituents in the compound are the same.

[0065] In the above formula (1), the above R 1 In particular, a monovalent group having 7 to 10 carbon atoms, formed by bonding a phenyl group to 1 to 3 linear alkyl groups having 1 to 4 carbon atoms, is preferred, and a monovalent group having 7 to 10 carbon atoms, formed by bonding a phenyl group to 1 linear alkyl group having 1 to 4 carbon atoms, is more preferred. Specifically, the above R 1 The preferred R is a p-tolyl group, m-tolyl group, o-tolyl group, 2,5-dimethylphenyl group, 2,4-dimethylphenyl group, 3,5-dimethylphenyl group, 2,3-dimethylphenyl group, 3,4-dimethylphenyl group, or mesitylene group, with the p-tolyl group being more preferred. 1 In that case, the color development and shelf life may be better.

[0066] In the above formula (1), A 1 Among the carbon atoms constituting the benzene ring, the above R 1 -SO3- can bond to carbon atoms that are not bonded. Also, multiple A 1The substitution positions may be the same or different between one benzene ring and the other. 1 The preferred substitution positions are the 2nd, 3rd, and 4th positions.

[0067] A above 1 Examples of hydrocarbon groups having 1 to 4 carbon atoms include alkyl groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, s-butyl, and t-butyl groups.

[0068] In formula (1) above, p is preferably an integer between 0 and 2, more preferably an integer between 0 and 1, and even more preferably 0.

[0069] The compound represented by formula (1) in this embodiment may include, but is not limited to, the following specific compounds.

[0070] In other words, the compounds represented by the above formula (1) are N,N'-di-[3-(o-toluenesulfonyloxy)phenyl]urea, N,N'-di-[3-(m-toluenesulfonyloxy)phenyl]urea, N,N'-di-[3-(p-toluenesulfonyloxy)phenyl]urea, N,N'-di-[3-(p-toluenesulfonyloxy)-4-methylphenyl]urea, N,N'-di-[3-(p-xylenesulfonyloxy)phenyl]urea, and N,N'-di-[3-(m-xylenesulfonyloxy)phenyl]urea. Examples include N,N'-di-[3-(mesitylenesulfonyloxy)phenyl]urea, N,N'-di-[3-(benzenesulfonyloxy)phenyl]urea, N,N'-di-[3-(benzenesulfonyloxy)-4-methylphenyl]urea, N,N'-di-[3-(benzenesulfonyloxy)-4-ethylphenyl]urea, N,N'-di-[3-(benzenesulfonyloxy)-5-methylphenyl]urea, and N,N'-di-[3-(benzenesulfonyloxy)-4-propylphenyl]urea. Among these, the compound represented by formula (1) above is particularly preferred, namely the compound represented by formula (1a) below, i.e., N,N'-di-[3-(p-toluenesulfonyloxy)phenyl]urea.

[0071] [ka]

[0072] In the above formula (2), A 2 It is a hydrocarbon group having 1 to 4 carbon atoms, and multiple A 2 The integers q and r can be the same or different. q represents an integer between 0 and 4, and multiple qs can be the same or different. r represents an integer between 1 and 11.

[0073] In formula (2) above, the multiple -OH and -(OCH2CH2)2O- are directly bonded to carbon atoms constituting the benzene ring. Furthermore, the substitution positions of the multiple -OH and -(OCH2CH2)2O- may be the same or different as substitution positions on each benzene ring. Preferably, the substitution positions of the -OH and -(OCH2CH2)2O- are the same as substitution positions on each benzene ring, and more preferably, they are all at position 4 on each benzene ring. In this specification, in formula (2) above, the carbon atom on the benzene ring bonded to the sulfonyl group (-SO2-) is defined as position 1.

[0074] In the above formula (2), A 2 It can bond to carbon atoms in the benzene ring that are not bonded to the above-mentioned -OH group. Also, multiple A 2 The substitution positions on each benzene ring may be the same or different from each other. 2 The substitution positions are preferably the same as the substitution positions on each benzene ring.

[0075] A above 2 Examples of hydrocarbon groups having 1 to 4 carbon atoms include alkyl groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, s-butyl, and t-butyl groups.

[0076] In formula (2) above, q is preferably an integer between 0 and 2, more preferably an integer between 0 and 1, and even more preferably 0.

[0077] In formula (2) above, r is preferably an integer from 1 to 7.

[0078] Among the compounds represented by formula (2) above, the compound represented by formula (2a) below, namely α-{4-[(hydroxyphenyl)sulfonyl]phenyl}-Ω-hydroxypoly(degree of polymerization 1-7)(oxyethyleneoxyethyleneoxy-p-phenylenesulfonyl-p-phenylene), is particularly preferred.

[0079] [ka]

[0080] In equation (2a) above, s represents an integer from 1 to 7.

[0081] The above-mentioned color developer may contain the compound represented by formula (1) alone, or it may contain two or more compounds represented by formula (1). In particular, the compound represented by formula (1) preferably contains the compound represented by formula (1a). Furthermore, it is preferable that the above-mentioned color developer must contain at least the compound represented by formula (1a). In addition, the above-mentioned color developer may contain the compound represented by formula (2) alone, or it may contain two or more compounds represented by formula (2). In particular, the compound represented by formula (2) preferably is the compound represented by formula (2a). Furthermore, it is preferable that the above-mentioned color developer must contain at least the compound represented by formula (2a). In addition, the above-mentioned color developer may contain both the compound represented by formula (1) and the compound represented by formula (2).

[0082] Furthermore, the above-mentioned color developer may also contain other color developers (other color developers) other than the compound represented by formula (1) and / or the compound represented by formula (2), to the extent that they do not impair the effects of the present invention.

[0083] Other color developers include, for example, known non-phenol color developers such as 3-[(3-phenylureido)phenyl]-4-methylbenzenesulfonate (trade name: TG-MD), N-3-[(p-toluenesulfonyl)oxy]phenyl-N'-(p-toluenesulfonyl)-urea (trade name: PF-201), N-[2-(3-phenylureido)phenyl]-benzenesulfonamide (trade name: NKK-1304), 4,4'-isopropylidenediphenol (BPA), 4,4'-dihydroxydiphenylsulfone (BPS), 4-allyloxy-4'-hydroxydiphenylsulfone (trade name: BPS-MAE), 4-allyloxy-4'-hydroxydiphenylsulfone (trade name: TGSA), 2,2'-diallyl-4,4'-sulfonyldiphenol (trade name: TG-SH), 4-hydroxy-4'-isopropoxydiphenylsulfone ( Product name: D-8), N-(m-tolylaminocarbonyl)-methionine, N-(m-tolylaminocarbonyl)-phenylalanine and N-(phenylaminocarbonyl)-phenylalanine, 1,1-bis(p-hydroxyphenyl)cyclohexane, 1,1-bis(p-hydroxyphenyl)propane, 2,2-bis(p-hydroxyphenyl)propane, 2,2-bis(p-hydroxyphenyl)butane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, 2,2'-methylenebis(4-chlorophenol), 2,2-bis(4-hydroxyphenyl)-4-methylpentane, poly(4-hydroxybenzoic acid), benzyl 4-hydroxybenzoate, 2,4-bis(phenylsulfonyl)phenol, 3,5-bis(α-methylbenzyl)salicylic acid, bis[4-(n-octyloxycarbonylamino)salicylate zinc], 4,Known color developers include 4'-bis(p-tolylsulfonylaminocarbonylamino)diphenylmethane, 4-hydroxybenzenesulfonanilide, N-(2-hydroxyphenyl)-2-[(4-hydroxyphenyl)thio]acetamide, N-(4-hydroxyphenyl)-2-[(4-hydroxyphenyl)thio]acetamide, 4-[4-(4-{4-[4-(1-methylethoxy)phenylsulfonyl]phenoxy}butoxy)phenylsulfonyl]phenol, and 4-tert-butylphenol-formaldehyde polycondensate.

[0084] The total content of the compound represented by formula (1) and / or the compound represented by formula (2) is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more, based on 100% by mass of the total amount of color developer in the thermal recording layer 4. The total content of the compound represented by formula (1) and / or the compound represented by formula (2) is also preferably within the above range.

[0085] The content of the above-mentioned color developer is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more, based on 100% by mass of the total solid content of the thermal recording layer 4. Furthermore, the content of the above-mentioned color developer is preferably 60% by mass or less, more preferably 55% by mass or less, and even more preferably 50% by mass or less, based on 100% by mass of the total solid content of the thermal recording layer 4.

[0086] Examples of the binders mentioned above include those similar to the resins listed in the section on the undercoat layer. Other examples include starch, casein, gelatin, polyamide, polyacrylamide, hydroxyethylcellulose, methylcellulose, carboxymethylcellulose, hydroxypropylcellulose, polyvinyl acetate, isobutylene-maleic anhydride copolymer, diisobutylene-maleic anhydride copolymer, vinyl acetate-maleic anhydride copolymer, methylvinyl-maleic anhydride copolymer, isopropylene-maleic anhydride copolymer, styrene-butadiene copolymer, polyvinyl chloride, polyvinylidene chloride, vinyl chloride-vinyl acetate copolymer, polyurethane, polystyrene, polyvinylpyrrolidone, acrylonitrile, methyl vinyl ether, etc. These binders can be used individually or in combination of two or more types.

[0087] The binder content is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, based on 100% by mass of the total solid content of the thermal recording layer 4. Furthermore, the binder content is preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less, based on 100% by mass of the total solid content of the thermal recording layer 4.

[0088] Examples of the above-mentioned fillers include those similar to those listed in the section on the undercoat layer.

[0089] The content of the above-mentioned filler is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 7.5% by mass or more, based on 100% by mass of the total solid content of the thermal recording layer 4. Furthermore, the content of the above-mentioned filler is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less, based on 100% by mass of the total solid content of the thermal recording layer 4.

[0090] Examples of the above lubricants include hydrocarbon waxes such as paraffin, polyethylene, and polystyrene; ester waxes such as carnauba wax; oils such as silicone oil and whale oil; fatty acids such as oleic acid and stearic acid; and metal soaps such as zinc stearate. These lubricants can be used individually or in combination of two or more.

[0091] The content of the above lubricant is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more, based on 100% by mass of the total solid content of the thermal recording layer 4. Furthermore, the content of the above lubricant is preferably 15% by mass or less, and more preferably 10% by mass or less, based on 100% by mass of the total solid content of the thermal recording layer 4.

[0092] Examples of the wetting agents mentioned above include those similar to those listed in the section on the undercoat layer.

[0093] The content of the above-mentioned wetting agent is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.1% by mass or more, based on 100% by mass of the total solid content of the thermal recording layer 4. Furthermore, the content of the above-mentioned wetting agent is preferably 3% by mass or less, and more preferably 1% by mass or less, based on 100% by mass of the total solid content of the thermal recording layer 4.

[0094] Examples of the sensitizers mentioned above include known sensitizers such as higher fatty acid amides like stearate amide, methylol stearate amide, methylenebisstearate amide, and ethylenebisstearate amide; higher fatty acid anilides like stearate anilide; aromatic ethers such as 1,2-diphenoxyethane, 1,4-diphenoxybutane, 1,2-bis(3-methylphenoxy)ethane, and 1,2-bis(4-methoxyphenoxy)ethane; 1-benzyloxynaphthalene, 2-benzyloxynaphthalene, 2,6-diisopropylnaphthalene; di(p-chlorobenzyl) oxalate, di(p-methylbenzyl) oxalate, dibenzyl oxalate, p-benzylbiphenyl, m-terphenyl, diphenylsulfone, p-benzyloxybenzoate benzyl, dibenzyl terephthalate, and p-toluenesulfonamide. These sensitizers can be used alone or in combination of two or more.

[0095] Examples of the crosslinking agents mentioned above include zirconium carbonate compounds such as zirconium carbonate and ammonium zirconium carbonate; and inorganic crosslinking agents such as zirconium acetate. These crosslinking agents can be used individually or in combination of two or more.

[0096] For example, the coating amount (dry mass) of the thermal recording layer 4 is 0.3 g / m². 2 ~10g / m 2 Preferably, and more preferably, 2.0 g / m 2 ~5.5g / m 2 Therefore, if the amount of coating is within the above range, it is easier to achieve more appropriate color development.

[0097] (Middle class) The intermediate layer 5 is a layer provided between the thermal recording layer 4 and the ultraviolet absorption layer 6, with the purpose of protecting the thermal recording layer 4 from various factors. These factors include not only common factors such as abrasion, moisture, and oil, but also the ultraviolet absorber in the ultraviolet absorption layer 6. This is because, in the present invention, it has been found that if the ultraviolet absorber migrates to the thermal recording layer and is further exposed to factors such as oil, it can lead to a decrease in preservation performance, such as the disappearance of the printed area, and that such a decrease in preservation performance can be suppressed by laminating the ultraviolet absorption layer 6 via the intermediate layer 5. In other words, the intermediate layer 5 of the present invention can function as a layer that protects the thermal recording layer 4 from the migration of the ultraviolet absorber contained in the ultraviolet absorption layer 6, and therefore can be a protective layer or part of a protective layer. By providing such an intermediate layer 5, various preservation properties of the thermal recording body 1, such as oil resistance, plasticizer resistance, and alcohol resistance, can be further improved.

[0098] The intermediate layer 5 can be formed using, for example, a binder such as a resin. In particular, from the viewpoint of preventing the migration of the ultraviolet absorber and further improving the shelf life, the intermediate layer 5 is preferably a cured layer. As the cured layer, a known cured layer can be used, for example, a layer having a crosslinked structure. Such a cured layer can be formed by a known method, and typically, it can be formed by forming a crosslinked structure using a curable resin, a crosslinking agent, etc., and then curing it. The intermediate layer 5 may also contain other components. Examples of these other components include wetting agents and preservatives.

[0099] Examples of binders mentioned above include those listed in the sections on the undercoat layer and the thermal recording layer. Furthermore, from the viewpoint of protecting the thermal recording layer 4, it is preferable that the binder includes a core-shell type resin in which hydrophobic core particles are coated with a water-soluble shell polymer. For example, the core-shell type resin can be one commercially available under the name Barrier Star (manufactured by Mitsui Chemicals, Inc.). These binders can be used individually or in combination of two or more types.

[0100] The binder described above preferably contains at least a cured resin. The cured resin is a resin obtained by curing the curable resin (post-curing resin). Examples of the curable resin include a resin having a curable functional group. The curable functional group is a functional group that can react with other curable functional groups or the crosslinking agent to form a crosslinked structure.

[0101] Examples of the curable functional groups include carboxyl groups, azetidinium groups, oxazoline groups, epoxy groups, aziridyl groups, amino groups, hydroxyl groups, and isocyanate groups. Carboxyl groups and azetidinium groups are preferred as the curable functional groups. Furthermore, preferred resins having the curable functional groups are carboxyl group-containing resins such as carboxyl group-containing acrylic resins and azetidinium group-containing resins such as azetidinium group-containing epichlorohydrin resins. Furthermore, the carboxyl group-containing resin, such as the carboxyl group-containing acrylic resin, may or may not be a core-shell type resin. From the viewpoint of protecting the heat-sensitive recording layer 4, etc., it is preferable that the carboxyl group-containing resin includes a core-shell type resin. When the carboxyl group-containing resin is a core-shell type resin, it is preferable that at least the water-soluble shell polymer has carboxyl groups. It is presumed that the water-soluble shell polymer having carboxyl groups further improves water solubility and facilitates the formation of the crosslinked structure.

[0102] Examples of the carboxyl group-containing acrylic resins mentioned above include carboxyl group-containing acrylic resins, carboxyl group-containing styrene-acrylic resins, carboxyl group-containing acrylic-urethane resins, carboxyl group-containing acrylamide resins, and carboxyl group-containing vinyl acetate-acrylic resins. In other words, resins having structural units derived from at least (meth)acrylic acid (salt) in the main chain of the resin, or acrylic resins containing carboxyl groups in the side chains are preferred. In this specification, the carboxyl group in the "carboxyl group-containing resin" may be a free carboxyl group or an acid anhydride group (specifically, a dicarboxylic acid anhydride group). Furthermore, the acid anhydride group may be partially ring-opened to become a carboxyl group. In the carboxyl group-containing resin, some or all of the carboxyl groups may be neutralized with an alkali.

[0103] Examples of the above-mentioned azetidinium group-containing epichlorohydrin resins include azetidinium group-containing polyamide epichlorohydrin resins, azetidinium group-containing polyamine epichlorohydrin resins, and azetidinium group-containing polyamide polyamine epichlorohydrin resins.

[0104] Examples of the crosslinking agents mentioned above include those similar to those listed in the section on thermal recording layers. Among these, zirconium carbonate and zirconium ammonium carbonate are preferred as crosslinking agents. Zirconium compounds such as zirconium carbonate are suitable for use as crosslinking agents because the zirconium ions act as reaction sites, reacting with the curable functional groups to easily form a crosslinked structure and improving the water resistance of the thermal recording material. These crosslinking agents can be used individually or in combination of two or more.

[0105] The above-mentioned cured layer can be produced, for example, by reacting a curable resin having a curable functional group (first reaction site) with another curable resin having a curable functional group (second reaction site) or a crosslinking agent having a reaction site (second reaction site), thereby causing a reaction between the first reaction site and the second reaction site to form a bond. That is, it is preferable that the intermediate layer 5 includes a crosslinked structure derived from the first reaction site and the second reaction site. In this specification, the bond formed between the first reaction site and the second reaction site includes covalent bonds and non-covalent bonds (e.g., hydrogen bonds). These curable functional groups can be used individually or in combination of two or more types.

[0106] Examples of combinations of the first reaction site and the second reaction site include carboxyl group and azetidinium group, azetidinium group and carboxyl group, carboxyl group and zirconium ion, hydroxyl group and zirconium ion, carboxyl group and epoxy group, epoxy group and carboxyl group, carboxyl group and aziridyl group, aziridyl group and carboxyl group, hydroxyl group and isocyanate group, isocyanate group and hydroxyl group, etc. Among these, the combination of carboxyl group and azetidinium group is preferred from the viewpoint that it is easy to form a crosslinked structure even at room temperature and easy to prevent unexpected color development of the heat-sensitive recording layer 4. That is, it is preferable that the crosslinked structure includes a crosslinked structure derived from a carboxyl group and an azetidinium group. These combinations may be one or two or more.

[0107] As for the combination of curable resins mentioned above, a combination of a carboxyl group-containing resin and an azetidinium group-containing resin is preferred, and more specifically, a combination of a carboxyl group-containing acrylic resin and an azetidinium group-containing epichlorohydrin resin is more preferred. With such a combination, it is easier to form a cross-linked structure appropriately, which further suppresses the migration of the ultraviolet absorber in the ultraviolet absorption layer 6 to the thermal recording layer 4, and suppresses the discoloration of the printed area, thus making it easier to achieve both light resistance and storage properties.

[0108] The total content of the carboxyl group-containing resin and the azetidinium group-containing resin is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more, based on 100% by mass of the total amount of binder in the intermediate layer 5. The total content may be substantially 100% by mass, based on 100% by mass of the total amount of binder in the intermediate layer 5. When the total content is within the above range, the crosslinked structure is formed more sufficiently, the curability becomes more appropriate, and the shelf life is even better. It is also preferable that the total content of the carboxyl group-containing acrylic resin and the azetidinium group-containing epichlorohydrin resin is within the above range.

[0109] When the intermediate layer 5 contains a carboxyl group-containing resin and an azetidinium group-containing resin, the mass ratio of the azetidinium group-containing resin in the intermediate layer 5 to the carboxyl group-containing resin in the intermediate layer 5 (mass of azetidinium group-containing resin / mass of carboxyl group-containing resin) is preferably 0.01 to 0.5, more preferably 0.02 to 0.3, and even more preferably 0.03 to 0.1. Furthermore, the mass ratio of the azetidinium group-containing epichlorohydrin resin in the intermediate layer 5 to the carboxyl group-containing acrylic resin in the intermediate layer 5 (mass of azetidinium group-containing epichlorohydrin resin / mass of carboxyl group-containing acrylic resin) is preferably within the above range.

[0110] The binder content is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more, based on 100% by mass of the total solid content of the intermediate layer 5.

[0111] Examples of the wetting agents mentioned above include those similar to those listed in the section on the undercoat layer.

[0112] The content of the above-mentioned wetting agent is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.1% by mass or more, based on 100% by mass of the total solid content of the intermediate layer 5. Furthermore, the content of the above-mentioned wetting agent is preferably 3% by mass or less, and more preferably 1% by mass or less, based on 100% by mass of the total solid content of the intermediate layer 5.

[0113] For example, the coating amount (dry mass) of the intermediate layer 5 described above is 0.1 g / m². 2 ~5g / m 2 Preferably, and more preferably, 1.0 g / m 2 ~3.0g / m 2 Therefore, if the amount of coating is within the above range, it is easier to achieve better preservation properties.

[0114] (UV-absorbing layer) The ultraviolet absorbing layer 6 is a layer containing an ultraviolet absorbing agent. In the thermal recording body 1 of the present invention, the ultraviolet absorbing layer 6 is provided on the side of the intermediate layer 5 opposite to the side on which the thermal recording layer 4 is provided, and is a layer intended to protect the thermal recording layer 4 from various factors. These factors include not only common factors such as abrasion, moisture, and oil, but also light such as sunlight and fluorescent lights. In other words, the ultraviolet absorbing layer 6 of the present invention can function as a layer that protects the thermal recording layer 4 from light, and can therefore be a protective layer or part of a protective layer. By providing such an ultraviolet absorbing layer 6, it is possible to suppress ultraviolet rays in the light from reaching the thermal recording layer 4, and to suppress unexpected color development, discoloration (e.g., yellowing of non-printed areas), and decolorization caused by light, thereby providing light resistance to the thermal recording body 1.

[0115] Furthermore, the ultraviolet absorption layer 6 may or may not be located on the surface (i.e., one end face) of the thermal recording body 1. If the ultraviolet absorption layer 6 is provided on the surface of the thermal recording body 1, the ultraviolet absorption layer 6 may be the layer that comes into contact with the thermal head. Also, both surfaces of the ultraviolet absorption layer 6 may be smooth, both surfaces may have irregularities, or one surface of the layer may be smooth and the other surface may have irregularities. If the ultraviolet absorption layer 6 is located on the surface of the thermal recording body 1, it is preferable that the ultraviolet absorption layer 6 has irregularities on the surface opposite to the surface where the intermediate layer 5 is located. With such a configuration, the matching suitability with the thermal head is improved, making it easier to achieve better print quality.

[0116] The ultraviolet absorbing layer 6 can be formed using, for example, a binder such as a resin and an ultraviolet absorber. In particular, from the viewpoint of preventing migration of the ultraviolet absorber and further improving shelf life, the ultraviolet absorbing layer 6 is preferably a cured layer. Known cured layers can be used as the cured layer, for example, a layer having a crosslinked structure. The ultraviolet absorbing layer 6 may also contain other components. Examples of these other components include fillers, lubricants, crosslinking agents, wetting agents, and preservatives.

[0117] Examples of the binders mentioned above include those similar to those listed under the sections for the undercoat layer, thermal recording layer, and intermediate layer. These binders can be used individually or in combination of two or more types.

[0118] The binder described above preferably contains at least a cured resin. The cured resin, the curable resin for obtaining the cured resin, and the curable functional groups possessed by the curable resin are all the same as those listed in the section on the intermediate layer. These cured resins, curable resins, and curable functional groups can all be used individually or in combination of two or more types.

[0119] Preferred curable functional groups are carboxyl groups and azetidinium groups. Furthermore, preferred resins having these curable functional groups are carboxyl group-containing resins such as carboxyl group-containing acrylic resins and azetidinium group-containing resins such as azetidinium group-containing epichlorohydrin resins.

[0120] Examples of the carboxyl group-containing acrylic resins mentioned above include those listed in the section on intermediate layers.

[0121] Examples of the above-mentioned azetidinium group-containing epichlorohydrin resins include those similar to those listed in the section on intermediate layers.

[0122] Examples of the crosslinking agents mentioned above include those similar to those listed in the section on the thermal recording layer. Among these, zirconium carbonate and zirconium ammonium carbonate are preferred as crosslinking agents. These crosslinking agents can be used individually or in combination of two or more.

[0123] The content of the above crosslinking agent is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more, based on 100% by mass of the total solid content of the ultraviolet absorption layer 6. Furthermore, the content of the above crosslinking agent is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less, based on 100% by mass of the total solid content of the ultraviolet absorption layer 6.

[0124] The combinations of the first reaction site and the second reaction site in the ultraviolet absorption layer 6 are the same as those listed in the section on the intermediate layer. In particular, from the viewpoint of improving heat resistance and enhancing suitability for thermal heads by forming a crosslinked structure containing metal ions, the combination of a carboxyl group and a zirconium ion, and the combination of a hydroxyl group and a zirconium ion are preferred. That is, the crosslinked structure preferably includes a crosslinked structure derived from a carboxyl group and a zirconium ion and / or a crosslinked structure derived from a hydroxyl group and a zirconium ion. These combinations may be one or two or more.

[0125] The ultraviolet absorbing layer 6 preferably contains at least a carboxyl group-containing resin as a binder and an inorganic crosslinking agent as a crosslinking agent. Specifically, it is preferable to contain at least a carboxyl group-containing acrylic resin as a binder and a zirconium carbonate compound as a crosslinking agent. With such a configuration, a crosslinked structure is appropriately formed, which can improve the printability and storage properties of the thermal recording body 1.

[0126] When the UV-absorbing layer 6 contains a carboxyl group-containing resin and an inorganic crosslinking agent, the mass ratio of the inorganic crosslinking agent in the UV-absorbing layer 6 to the carboxyl group-containing resin in the UV-absorbing layer 6 (mass of inorganic crosslinking agent / mass of carboxyl group-containing resin) is preferably 0.01 to 0.5, more preferably 0.02 to 0.3, and even more preferably 0.03 to 0.1. Furthermore, the mass ratio of the zirconium carbonate compound in the UV-absorbing layer 6 to the carboxyl group-containing acrylic resin in the UV-absorbing layer 6 (mass of zirconium carbonate compound / mass of carboxyl group-containing acrylic resin) is preferably within the above range.

[0127] The content of the carboxyl group-containing resin is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more, based on 100% by mass of the total amount of binder in the ultraviolet absorption layer 6. When the content is within the above range, the cross-linked structure is formed more sufficiently, the curability becomes more appropriate, and the shelf life is even better. It is also preferable that the content of the carboxyl group-containing acrylic resin is within the above range.

[0128] The binder content is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more, based on 100% by mass of the total solid content of the ultraviolet absorption layer 6. Furthermore, the binder content is preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less, based on 100% by mass of the total solid content of the ultraviolet absorption layer 6.

[0129] The above UV absorber includes a benzotriazole-based UV absorber and / or a hydroxyphenyltriazine-based UV absorber. It is more preferable that the above UV absorber includes a hydroxyphenyltriazine-based UV absorber. These UV absorbers can be used individually or in combination of two or more.

[0130] The above-mentioned benzotriazole-based ultraviolet absorber is a compound having a benzotriazole skeleton. The molecular weight of the above-mentioned benzotriazole-based ultraviolet absorber is preferably 500 or less. Examples of the above-mentioned benzotriazole-based UV absorbers include 2-(2-hydroxy-5-tert-butylphenyl)-2H-benzotriazole (trade name "TINUVIN PS", manufactured by BASF), benzenepropanoic acid and ester compounds of 3-(2H-benzotriazole-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy(C7-9 side chain and linear alkyl) (trade name "TINUVIN 384-2", manufactured by BASF), a mixture of octyl 3-[3-tert-butyl-4-hydroxy-5-(5-chloro-2H-benzotriazole-2-yl)phenyl]propionate and 2-ethylhexyl-3-[3-tert-butyl-4-hydroxy-5-(5-chloro-2H-benzotriazole-2-yl)phenyl]propionate (trade name "TINUVIN PS"). Reaction product of methyl 3-(3-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (product name "TINUVIN 900", manufactured by BASF), 2-(2H-benzotriazol-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol (product name "TINUVIN 928", manufactured by BASF), reaction product of methyl 3-(3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate / polyethylene glycol 300 (product name "TINUVIN 1130", manufactured by BASF), 2-(2H-benzotriazol-2-yl)-p-cresol (product name "TINUVIN P (manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (trade name "TINUVIN 234", manufactured by BASF), 2-[5-chloro-2H-benzotriazol-2-yl]-4-methyl-6-(tert-butyl)phenol (trade name "TINUVIN 326", manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (trade name "TINUVIN 328", manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol (trade name "TINUVIN 329", manufactured by BASF), 2,2'-methylenebis[6-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol] (trade name "TINUVIN 360", manufactured by BASF), reaction product of methyl 3-(3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate and polyethylene glycol 300 (trade name "TINUVIN 213", manufactured by BASF), 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol (trade name "TINUVIN Examples include 571 (manufactured by BASF), 2-[2-hydroxy-3-(3,4,5,6-tetrahydrophthalimidomethyl)-5-methylphenyl]benzotriazole (trade name "Sumisorb 250", manufactured by Sumitomo Chemical Co., Ltd.), and 2,2'-methylenebis[6-(2H-benzotriazol-2-yl)-4-tert-octylphenol] (trade name "ADEKA Stab LA-31", manufactured by ADEKA Corporation). Additionally, commercially available products such as "Shineguard BZ-29" and "Shineguard W-51" (both manufactured by Senka Co., Ltd.) can also be used.

[0131] The above-mentioned hydroxyphenyltriazine-based UV absorbers are compounds having a hydroxyphenyltriazine skeleton. Examples of the above-mentioned hydroxyphenyltriazine-based UV absorbers include the reaction product of 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine-2-yl)-5-hydroxyphenyl and [(C10-C16 (mainly C12-C13) alkyloxy)methyl]oxirane (trade name "TINUVIN 400", manufactured by BASF), 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine-2-yl]-5-[3-(dodecyloxy)-2-hydroxypropoxy]phenol), and the reaction product of 2-(2,4-dihydroxyphenyl)-4,6-bis-(2,4-dimethylphenyl)-1,3,5-triazine and (2-ethylhexyl)-glycidic acid ester (trade name "TINUVIN 400"). 405 (manufactured by BASF), 2,4-bis(2-hydroxy-4-butoxyphenyl)-6-(2,4-dibutoxyphenyl)-1,3,5-triazine (product name "TINUVIN 460", manufactured by BASF), 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-[(hexyl)oxy]-phenol (product name "TINUVIN 1577", manufactured by BASF), 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-[2-(2-ethylhexanoyloxy)ethoxy]-phenol (product name "ADEKA Stab LA-46", manufactured by ADEKA Corporation), 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine (product name "TINUVIN Examples include "479" (manufactured by BASF). Additionally, commercially available products such as "Shineguard TA-04" and "Shineguard TA-22" (both manufactured by Senka Co., Ltd.) can also be used.

[0132] Furthermore, the above-mentioned ultraviolet absorber may also contain ultraviolet absorbers other than benzotriazole-based ultraviolet absorbers and / or hydroxyphenyltriazine-based ultraviolet absorbers (other ultraviolet absorbers) to the extent that they do not impair the effects of the present invention.

[0133] The content of the above-mentioned ultraviolet absorber is preferably 1% by mass or more, more preferably 2.5% by mass or more, even more preferably 5% by mass or more, even more preferably 10% by mass or more, and particularly preferably 20% by mass or more, based on 100% by mass of the total solid content of the ultraviolet absorption layer 6. Furthermore, the content of the above-mentioned ultraviolet absorber is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less, based on 100% by mass of the total solid content of the ultraviolet absorption layer 6. When the above-mentioned content is within the above range, it is easier to maintain good storage properties while appropriately imparting light resistance.

[0134] The total content of the above-mentioned benzotriazole-based ultraviolet absorber and / or hydroxyphenyltriazine-based ultraviolet absorber is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more, based on 100% by mass of the total amount of ultraviolet absorbers in the ultraviolet absorption layer 6. The above total content may be substantially 100% by mass, based on 100% by mass of the total amount of ultraviolet absorbers in the ultraviolet absorption layer 6. When the above total content is within the above range, it is easier to make the light resistance more appropriate. Furthermore, it is preferable that the content of the benzotriazole-based ultraviolet absorber is within the above range, and it is also preferable that the content of the hydroxyphenyltriazine-based ultraviolet absorber is within the above range.

[0135] Examples of the above-mentioned fillers include those similar to those listed in the section on the undercoat layer.

[0136] The content of the above-mentioned filler is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more, based on 100% by mass of the total solid content of the ultraviolet absorption layer 6. Furthermore, the content of the above-mentioned filler is preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less, based on 100% by mass of the total solid content of the ultraviolet absorption layer 6.

[0137] Examples of the lubricants mentioned above include those similar to those listed in the section on the thermal recording layer.

[0138] The content of the above lubricant is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, based on 100% by mass of the total solid content of the ultraviolet absorption layer 6. Furthermore, the content of the above lubricant is preferably 20% by mass or less, and more preferably 15% by mass or less, based on 100% by mass of the total solid content of the ultraviolet absorption layer 6.

[0139] Examples of the wetting agents mentioned above include those similar to those listed in the section on the undercoat layer.

[0140] The content of the above-mentioned wetting agent is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.1% by mass or more, based on 100% by mass of the total solid content of the ultraviolet absorption layer 6. Furthermore, the content of the above-mentioned wetting agent is preferably 5% by mass or less, and more preferably 3% by mass or less, based on 100% by mass of the total solid content of the ultraviolet absorption layer 6.

[0141] For example, the coating amount (dry mass) of the above-mentioned UV-absorbing layer 6 is 0.1 g / m². 2 ~5g / m 2 Preferably, and more preferably, 1.0 g / m 2 ~3.0g / m 2 Therefore, if the amount of coating is within the above range, it is easier to achieve better preservation properties.

[0142] [Method for manufacturing thermal recording media] The method for manufacturing the thermal recording body of the present invention is not particularly limited, and known or conventional methods can be applied. For example, the thermal recording body 1 shown in Figure 1 can be prepared by dispersing the components contained in the thermal recording layer 4 in a solvent such as water to prepare the coating solution for the thermal recording layer. The intermediate layer coating solution and the ultraviolet absorption layer coating solution can also be prepared by similar means. Next, the thermal recording layer coating solution can be applied to one side of the substrate 2 and dried to form the thermal recording layer 4. Furthermore, the intermediate layer coating solution can be applied to the surface of the thermal recording layer 4 and dried to form the intermediate layer 5, and the ultraviolet absorption layer 6 can be applied to the surface of the intermediate layer 5 and dried to form the ultraviolet absorption layer 6.

[0143] (Preparation process) The above-mentioned thermal recording layer coating solution may be prepared by pre-dispersing all the materials in the same solvent. Alternatively, the dye and developer, which react with each other, may be prepared as separate dispersions and then mixed to form the thermal recording layer coating solution. In this case, the other components may be added to either the dispersion containing the dye or the dispersion containing the developer, or to both. Methods for preparing the above-mentioned thermal recording layer coating solution include, for example, stirring, ultrasonic treatment, crushing treatment using a ball mill, bead mill, sand mill, high-pressure homogenizer, etc. The above-mentioned intermediate layer coating solution and the above-mentioned ultraviolet absorption layer coating solution can also be prepared by similar means. These methods can be used individually or in combination of two or more.

[0144] (Coating process) Methods for applying the above-mentioned thermal recording layer coating include, for example, direct application to the substrate, or application to a release liner and then transfer to the substrate. Examples of application methods include air knife coating, barrier blade coating, pure blade coating, rod blade coating, short dwell coating, curtain coating, die coating, and gravure coating. Manual application using a wire bar is also acceptable. The above-mentioned intermediate layer coating and UV absorption layer coating can also be applied by similar means. These methods can be used individually or in combination of two or more.

[0145] (drying process) Methods for drying the coating liquid for the thermal recording layer applied as described above include, for example, heat drying, room temperature drying, and vacuum drying. These methods can be used individually or in combination of two or more. The thermal recording layer 4 can be formed by these methods. The intermediate layer 5 and the ultraviolet absorption layer 6 can also be formed by similar means.

[0146] If the thermal recording body of the present invention comprises layers other than the substrate, thermal recording layer, intermediate layer, and ultraviolet absorbing layer, the above-described method can be used to form the other layers. For example, the thermal recording body 1 shown in Figure 2 can be manufactured by dispersing the components contained in the undercoat layer 3 in a solvent such as water to prepare an undercoat coating solution, then coating one side of the substrate 2 with the undercoat coating solution and drying it to form the undercoat layer 3, and then laminating the thermal recording layer 4, the intermediate layer 5, and the ultraviolet absorbing layer 6 on the undercoat layer 3 using the same method as described above.

[0147] In the method for manufacturing a thermal recording body of the present invention, each layer may be simultaneously coated in multiple layers using, for example, a curtain coater, or it may be formed individually and sequentially. Alternatively, some layers may be simultaneously coated, and some layers may be formed individually and sequentially. [Examples]

[0148] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way by these examples. Unless otherwise specified, the masses mentioned in the examples refer to the mass of each component (i.e., the mass after drying following layer formation). The raw materials used are as follows.

[0149] Dye 1: 3-Dibutylamino-6-methyl-7-anilinofluorane (ODB-2) Chromophallic developer 1: Compound represented by the above formula (1a) (N,N'-di-[3-(p-toluenesulfonyloxy)phenyl]urea) (product name "S-176", manufactured by Sanko Co., Ltd.) Chromochemical developer 2: Compound represented by the above formula (2a) (α-{4-[(hydroxyphenyl)sulfonyl]phenyl}-Ω-hydroxypoly(degree of polymerization 1-7)(oxyethyleneoxyethyleneoxy-p-phenylenesulfonyl-p-phenylene)) (product name "D-90", manufactured by Nippon Soda Co., Ltd.) Chromogen 3: 3-[(3-phenylureido)phenyl]-4-methylbenzenesulfonate (trade name "TG-MD", manufactured by Nippon Kayaku Co., Ltd.) Chromogen 4: N-[2-(3-phenylureido)phenyl]benzenesulfonamide (product name "NKK-1304", manufactured by Nippon Soda Co., Ltd.) Chromogen 5: 2,2'-diallyl-4,4'-sulfonyldiphenol (product name "TG-SH", manufactured by Nippon Kayaku Co., Ltd.) 6. Chromolytic agent: 4-hydroxy-4'-isopropoxydiphenylsulfone (product name "D-8", manufactured by Nippon Soda Co., Ltd.) Filler 1: Calcium carbonate Filler 2: Polystyrene Binder 1: Styrene-butadiene rubber Binder 2: Polyurethane-based binder Curable resin 1: Carboxylate group-containing acrylic resin A Curable resin 2: Carboxylate group-containing acrylic resin B Curable resin 3: Azetidinium group-containing epichlorohydrin-based resin Crosslinking agent 1: Zirconium carbonate ammonium Lubricant 1: Zinc stearate Lubricant 2: Polyethylene-based lubricant UV absorber 1: Hydroxyphenyltriazine-based UV absorber (product name "Shineguard TA-22", manufactured by Senka Co., Ltd.) UV absorber 2: Benzotriazole-based UV absorber (product name "Shineguard BZ-29", manufactured by Senka Co., Ltd.) Wetting agent 1: Acetylene glycol-based surfactant

[0150] Example 1 (Preparation of thermal recording media) <Undercoat layer> A coating solution for the undercoat layer was prepared by mixing 4.75 parts by mass of hollow particles, 15.2 parts by mass of styrene-acrylic resin as a binder, 0.05 parts by mass of acetylene glycol-based surfactant, and 80.05 parts by mass of water using a conventional method. The obtained undercoat layer solution was applied to one side of the substrate, high-quality paper, using a conventional method and dried to achieve a coating amount of 3.0 g / m². 2 An undercoat layer of (dry mass) was formed.

[0151] <Thermal recording layer> A thermal recording layer coating solution was prepared by mixing 25.2% by mass of dye 1, 39.6% by mass of developer 1, 17.3% by mass of filler 1, 15.1% by mass of binder 1, 2.5% by mass of lubricant 1, 0.3% by mass of wetting agent 1, and water using a conventional method. The obtained thermal recording layer coating solution was applied to the surface of the undercoat layer using a conventional method and dried, resulting in a coating amount of 3.8 g / m². 2 A thermal recording layer A with (dry mass) was formed.

[0152] <Middle class> A coating solution for the intermediate layer was prepared by mixing 93.8% by mass of curable resin 1, 5.6% by mass of curable resin 3, 0.6% by mass of wetting agent 1, and water using a conventional method. The obtained intermediate layer coating solution was applied to the surface of the thermal recording layer using a conventional method and dried, resulting in a coating amount of 1.6 g / m². 2 An intermediate layer A of (dry mass) was formed.

[0153] <UV absorbing layer> A coating solution for the ultraviolet absorbing layer was prepared by mixing 41.1% by mass of curable resin 2, 11.4% by mass of lubricant 2, 29.2% by mass of filler 1, 9.3% by mass of filler 2, 1.0% by mass of ultraviolet absorber 1, 2.5% by mass of crosslinking agent 1, 1.2% by mass of wetting agent 1, 4.3% by mass of binder 2, and water using a conventional method. The obtained coating solution for the ultraviolet absorbing layer was applied to the surface of the intermediate layer using a conventional method and dried, resulting in a coating amount of 1.3 g / m². 2 A UV-absorbing layer A of (dry mass) was formed to obtain the thermal recording material of Example 1.

[0154] Examples 2-11, Comparative Examples 1-7 Except for the fact that the thermal recording layer was prepared by mixing each compounding material in the mass ratio shown in Table 1, the intermediate layer was prepared by mixing each compounding material in the mass ratio shown in Table 2, and the ultraviolet absorption layer was prepared by mixing each compounding material in the mass ratio shown in Table 3, the thermal recording bodies of Examples 2 to 11 and Comparative Examples 1 to 7 were prepared in the same manner as in Example 1. The layer structure of the obtained thermal recording bodies is shown in Table 4. In Comparative Examples 1 to 3, the layer corresponding to the ultraviolet absorption layer of the present invention does not contain an ultraviolet absorber and is therefore referred to as the top coat layer.

[0155] [Table 1]

[0156] [Table 2]

[0157] [Table 3]

[0158] [evaluation] The thermal recording materials obtained in the examples and comparative examples were evaluated as follows. The results are shown in Table 4.

[0159] (1) Oil resistance A thermal recording material was prepared by printing on a thermal paper printing test device (manufactured by Okura Engineering Co., Ltd., device name: Pulse Simulator TH-M2 / PP) with the following settings: printing speed 50 mm / sec, applied voltage 17.0 V, head resistance 870 Ω, pulse width 0.488~1.394 ms, and applied energy 0.40 mJ / dot. This prepared thermal recording material was used as a test specimen. The optical density (printed area density) of the printed area of ​​the test specimen was measured using a spectrophotometer (manufactured by X-rite, device name: eXact). This measured value was defined as the printed area density (before testing). A thin piece of paper (Kimtowel) was placed on the surface of the printed area of ​​the test specimen, and two drops of edible oil (salad oil) were dropped onto the surface of the thin paper using a dropper. The specimen was then placed in a dryer set to 40°C and left to stand for 15 hours. Next, the test specimen was removed and left to stand at room temperature for another week. After that, the optical density of the printed area of ​​the test specimen was measured using the spectrophotometer described above. The measured value at this time was defined as the printed area density (after the test). The print retention rate was calculated by dividing the printed area density (after the test) by the printed area density (before the test).

[0160] (2) Plasticizer resistance After sandwiching the test specimen used in the above evaluation (1) between two PVC films (thickness: 40 μm), 300 g / cm² was applied to one side of the test specimen. 2 A weight was placed on the test specimen to apply a load, and it was placed in a dryer set to 40°C and left to stand for 15 hours. The test specimen was then removed and left to stand at room temperature for another week, after which the optical density of the printed area of ​​the test specimen was measured using the spectrophotometer described above. The measured value at this time was defined as the printed area density (after the test). The remaining percentage of the printed area was calculated in the same manner as in (1).

[0161] (3) Alcohol resistance Three drops of alcohol disinfectant (alcohol concentration: 80% by volume) were dropped onto the printed surface of the test specimen used in evaluation (1) above using a dropper. After standing for one minute, the printed surface of the test specimen was rubbed back and forth 100 times with a cotton swab, and the condition of the printed and unprinted areas was visually inspected. The alcohol resistance of the printed and unprinted areas was then evaluated according to the evaluation criteria below. [Evaluation Criteria] A: No (discoloration of printed areas / color development of non-printed areas) is observed. B: Slight discoloration of the printed area / color development of the non-printed area is observed. C: (Discoloration of printed area / Color development of non-printed area) is clearly visible. D: (Discoloration of printed area / Color development of non-printed area) is clearly observed.

[0162] (4) Lightfastness The Lab values ​​in the non-printed areas of the test specimen used in the evaluation (1) described above were measured using the spectrophotometer described above. The Lab values ​​at this time were defined as L value (before testing), a value (before testing), and b value (before testing), respectively. Next, the test specimen was placed inside a weather resistance tester (manufactured by Iwasaki Electric Co., Ltd., device name: EYE SUN-CUBE Xenon, model number: SCX400 / 1-2), with an irradiation distance of 400 mm and an irradiance of 50 W / m². 2 The Lab values ​​in the non-printed area after exposure to light for 10 hours under the specified conditions were measured in the same manner as described above. The Lab values ​​at this time were defined as L value (after test), a value (after test), and b value (after test), respectively. Then, ΔL was calculated by subtracting L value (after test) from L value (before test), Δa was calculated by subtracting a value (after test) from a value (before test), and Δb was calculated by subtracting b value (after test) from b value (before test). These were then applied to the following formula to calculate ΔE. The lightfastness was then evaluated based on the following evaluation criteria. ΔE={(ΔL) 2 +(Δa) 2 +(Δb) 2} 1 / 2 [Evaluation Criteria] A: ΔE is less than 6.0 B: ΔE is between 6.0 and 8.0 C:ΔE is between 8.0 and 10.0 D:ΔE is 10.0 or greater

[0163] [Table 4]

[0164] As shown in Table 4, when an intermediate layer was formed between a thermal recording layer containing a specific color developer and an ultraviolet absorbing layer (Examples 1-11), the materials exhibited excellent preservation properties such as oil resistance, plasticizer resistance, and alcohol resistance, as well as excellent light resistance. On the other hand, when no ultraviolet absorbing layer was provided (Comparative Example 1), light resistance was poor. Furthermore, when the layer containing the ultraviolet absorber was the intermediate layer (Comparative Example 2 or 3), oil resistance and plasticizer resistance tended to be worse than when the layer containing the same type of ultraviolet absorber was the ultraviolet absorbing layer (Examples 1-5 or 6-10). In addition, when a color developer other than the compound represented by formula (1) and the compound represented by formula (2) was used (Comparative Examples 4-7), one or more of the oil resistance, plasticizer resistance, or alcohol resistance were significantly inferior.

[0165] In summary, the configuration of the present invention and its variations are described below. [Note 1] A thermal recording body in which a thermal recording layer, an intermediate layer, and an ultraviolet absorbing layer are laminated in this order on a substrate, wherein the thermal recording layer contains a dye and a developer, the developer contains a compound represented by formula (1) and / or a compound represented by formula (2), and the ultraviolet absorbing layer contains an ultraviolet absorber, the ultraviolet absorber contains a benzotriazole-based ultraviolet absorber and / or a hydroxyphenyltriazine-based ultraviolet absorber. [Note 2] The thermal recording body described in Note 1, wherein the compound represented by formula (1) includes the compound represented by formula (1a). [Note 3] The thermal recording body according to Note 2, wherein the color developer comprises at least a compound represented by formula (1a). [Note 4] The thermal recording body according to any one of Notes 1 to 3, wherein the compound represented by formula (2) is the compound represented by formula (2a). [Note 5] The thermal recording body according to Note 4, wherein the color developer comprises at least a compound represented by formula (2a). [Note 6] The thermal recording body according to any one of Notes 1 to 5, wherein the content of the color developer is 10% by mass or more and 60% by mass or less based on 100% by mass of the total solid content of the thermal recording layer. [Note 7] The thermal recording body according to any one of Notes 1 to 6, wherein the total content of the compound represented by formula (1) and / or the compound represented by formula (2) is 50% by mass or more with respect to 100% by mass of the total amount of the color developer in the thermal recording layer. [Note 8] The thermal recording body according to any one of Notes 1 to 7, wherein the ultraviolet absorber comprises at least the benzotriazole-based ultraviolet absorber. [Note 9] The thermal recording body according to any one of Notes 1 to 8, wherein the ultraviolet absorber comprises at least the hydroxyphenyltriazine-based ultraviolet absorber. [Note 10] The thermal recording body according to any one of Notes 1 to 9, wherein the content of the ultraviolet absorber is 1% to 30% by mass based on 100% by mass of the total solid content of the ultraviolet absorbing layer. [Note 11] The intermediate layer is a thermal recording body according to any one of Notes 1 to 10, comprising a binder. [Note 12] The thermal recording body according to Note 11, wherein the content of the binder is 50% by mass or more with respect to 100% by mass of the total solid content of the intermediate layer. [Note 13] The thermal recording body according to either Note 11 or 12, wherein the binder comprises a carboxyl group-containing resin and an azetidinium group-containing resin. [Note 14] The thermal recording body according to Note 13, wherein the total content ratio of the carboxyl group-containing resin and the azetidinium group-containing resin is 50% by mass or more with respect to 100% by mass of the total amount of binder in the intermediate layer. [Note 15] The thermal recording body according to Note 13 or 14, wherein the mass ratio of the azetidinium group-containing resin to the carboxyl group-containing resin in the intermediate layer (mass of azetidinium group-containing resin / mass of carboxyl group-containing resin) is 0.01 to 0.5. [Note 16] The carboxyl group-containing resin is a carboxyl group-containing acrylic resin, as described in any one of Notes 13 to 15. [Note 17] The thermal recording body according to any one of Notes 13 to 16, wherein the azetidinium group-containing resin is an azetidinium group-containing epichlorohydrin resin. [Note 18] The intermediate layer is a thermal recording body according to any one of Notes 1 to 17, having a cross-linked structure. [Note 19] The thermal recording body according to Note 18, wherein the crosslinking structure includes a crosslinking structure derived from a first reaction site and a second reaction site. [Note 20] The combination of the first reaction site and the second reaction site is a combination of a carboxyl group and an azetidinium group, as described in Note 19. [Note 21] The thermal recording body according to any one of Notes 1 to 20, wherein the thermal recording body comprises an undercoat layer between the substrate and the thermal recording layer. [Explanation of Symbols]

[0166] 1. Thermal recording medium 2 Base material 3. Undercoat layer 4. Thermal recording layer 5. Middle Class 6. UV-absorbing layer

Claims

1. A thermal recording body is formed in which a thermal recording layer, an intermediate layer, and an ultraviolet absorbing layer are laminated on a substrate in this order. The thermal recording layer comprises a dye and a color developer. The color developer comprises a compound represented by the following formula (1) and / or a compound represented by the following formula (2). The aforementioned ultraviolet absorbing layer contains an ultraviolet absorbing agent, The aforementioned ultraviolet absorber comprises a benzotriazole-based ultraviolet absorber and / or a hydroxyphenyltriazine-based ultraviolet absorber, in a thermal recording body. 【Chemistry 1】 (In formula (1), R １ is a hydrocarbon group having 1 to 12 carbon atoms, which may have substituents, and a plurality of R １ They may be the same or different. A １ It is a hydrocarbon group having 1 to 4 carbon atoms, and multiple A １ (These values ​​may be the same or different. p represents an integer between 0 and 4, and multiple p values ​​may be the same or different.) 【Chemistry 2】 (In formula (2), A ２ It is a hydrocarbon group having 1 to 4 carbon atoms, and multiple A ２ (These can be the same or different. q represents an integer from 0 to 4, and multiple qs can be the same or different. r represents an integer from 1 to 11.)

2. The thermal recording body according to claim 1, wherein the compound represented by formula (1) includes the compound represented by the following formula (1a). 【Transformation 3】

3. The thermal recording body according to claim 1, wherein the color developer comprises at least a compound represented by formula (1a).

4. The thermal recording body according to claim 1, wherein the compound represented by formula (2) is the compound represented by the following formula (2a). 【Chemistry 4】 (In equation (2a), s represents an integer from 1 to 7.)

5. The thermal recording body according to claim 4, wherein the color developer comprises at least a compound represented by formula (2a).

6. The thermal recording body according to any one of claims 1 to 5, wherein the content of the ultraviolet absorber is 1% to 30% by mass based on 100% by mass of the total solid content of the ultraviolet absorbing layer.

7. The thermal recording body according to any one of claims 1 to 5, wherein the intermediate layer has a cross-linked structure.

8. The thermal recording body according to claim 7, wherein the crosslinking structure includes a crosslinking structure derived from a carboxyl group and an azetidinium group.

9. The thermal recording body according to any one of claims 1 to 5, wherein the thermal recording body comprises an undercoat layer between the substrate and the thermal recording layer.

Images