Release paper and thermal recording medium

Abstract

The present invention provides release paper that can be printed on the release layer, and also provides a thermal recording medium that is peelable from the topcoat layer and printable on the topcoat layer. The release paper 1 comprises a paper substrate 2 and a release layer 3 provided on the paper substrate 2. The release layer 3 contains a vinyl acetate-silicone copolymer resin. The dynamic friction coefficient of the surface of the release layer 3 is 0.30 or less, and the static friction coefficient of the surface of the release layer 3 is 0.19 or more. The thermal recording body 4 has a structure in which an adhesive layer 5, a thermal recording layer 9, and a top coat layer 11 are laminated. The top coat layer 11 contains a vinyl acetate-silicone copolymer resin. The dynamic friction coefficient of the surface of the top coat layer 11 is 0.30 or less, and the static friction coefficient of the surface of the top coat layer 11 is 0.19 or more.

Description

[Technical Field]

[0001] The present invention relates to release paper and thermal recording material. More specifically, the present invention relates to release paper having a release layer and thermal recording material having a top coat layer. [Background technology]

[0002] Adhesive sheets such as adhesive tapes and adhesive labels are supplied wound in a roll. Alternatively, even if they are supplied as laminated sheets, they are manufactured by being wound in a roll. In this case, it is common practice to provide a release liner (release paper) in the adhesive layer to prevent the upper and lower surfaces of the adhesive sheet from coming into contact and sticking together in the roll.

[0003] It is common practice to print on such release paper. When the substrate used for the release paper is transparent, it is possible to print on the release layer side of the transparent substrate. Examples of printable substrates for release paper are proposed in Patent Document 1. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2017-100359 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, conventional release layers repel printing inks, making printing difficult. Therefore, there is a need for release paper that can be printed on the surface of the release layer. This invention was conceived under these circumstances, and its purpose is to provide release paper that can be printed on the surface of the release layer.

[0006] By the way, a thermal recording medium develops color through a chemical reaction by heating with 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 thermal recording label for POS systems in retail stores and the like, receipt paper, and the like. In order to reduce the wear of the thermal head of a printer, the thermal recording medium generally has a top coat layer on the outermost layer on the surface. Further, when the thermal recording medium has adhesiveness, the surface having adhesiveness can be protected and stored by winding the thermal recording medium having adhesiveness on the surface opposite to the top coat layer and overlapping it with the top coat layer and the surface having adhesiveness. And when using the thermal recording medium, the surface having adhesiveness can be easily peeled off from the top coat layer and unwound from the wound body.

[0007] There may be a demand to print a lot number or the like on the top coat layer of the thermal recording medium. However, the top coat layer provided for the purpose of making the adhesive layer peelable usually repels printing ink. For this reason, there is a demand for a thermal recording medium that is peelable from the top coat layer and printable on the top coat layer.

[0008] The present invention has been conceived under such circumstances, and its object is to provide a thermal recording medium that is peelable from the top coat layer and printable on the top coat layer.

Means for Solving the Problems

[0009] As a result of intensive studies to achieve the above object, the present inventors have found that a specific release layer is peelable and printable. They have found that a specific top coat layer is peelable and printable. Further, the present invention has been completed based on these findings.

[0010] That is, the present invention includes a paper substrate and a release layer provided on the paper substrate. The release layer contains a vinyl acetate-silicone copolymer resin. The coefficient of dynamic friction of the surface of the above release layer is 0.30 or less. The present invention provides a release paper in which the static friction coefficient of the surface of the above-mentioned release layer is 0.19 or higher.

[0011] The above-mentioned coefficient of dynamic friction is preferably 0.11 to 0.30.

[0012] The static friction coefficient is preferably between 0.19 and 0.52.

[0013] The above release layer is placed on adhesive paper with an acrylic adhesive that conforms to JIS Z0237 (2009) and has an adhesive strength of 0.40 ± 0.15 N / 10 mm (standard value), and the adhesive is applied at 10 kg / cm². 2 It is preferable that the peel strength when T-shaped peeling is performed under conditions of 23°C and a peeling speed of 300 mm / min after being pressed with a load for 10 minutes is 1100 mN / 50 mm or less.

[0014] The above release layer may further contain an acrylic resin.

[0015] The above release layer may contain two types of vinyl acetate-silicone copolymer resins having a difference in static friction coefficient of 0.03 or more.

[0016] Furthermore, the present invention relates to a thermal recording body comprising an adhesive layer, a thermal recording layer, and a topcoat layer, The above topcoat layer contains vinyl acetate-silicone copolymer resin. The coefficient of dynamic friction of the surface of the above topcoat layer is 0.30 or less. The present invention provides a thermal recording material in which the static friction coefficient of the surface of the top coat layer is 0.19 or higher.

[0017] The above-mentioned coefficient of dynamic friction is preferably 0.11 to 0.30.

[0018] The static friction coefficient is preferably between 0.19 and 0.52.

[0019] The above topcoat layer is then applied to adhesive paper with an acrylic adhesive that conforms to JIS Z0237 (2009) with an adhesive strength of 0.40 ± 0.15 N / 10 mm (standard value), at a rate of 10 kg / cm². 2 It is preferable that the peel strength when T-shaped peeling is performed under conditions of 23°C and a peeling speed of 300 mm / min after being pressed with a load for 10 minutes is 1100 mN / 50 mm or less.

[0020] The above topcoat layer may further contain an acrylic resin.

[0021] The above topcoat layer may contain two types of vinyl acetate-silicone copolymer resins having a difference of 0.03 or more in static friction coefficients. [Effects of the Invention]

[0022] The release paper of the present invention is printable on the release layer. Therefore, the adhesive layer can be protected until use, it can be easily peeled off from the release layer when in use, and printing can be applied to the release layer.

[0023] The thermal recording material of the present invention is peelable from the topcoat layer and printable on the topcoat layer. Therefore, for example, by overlaying an adhesive surface on the topcoat layer, the surface can be protected until use, and can be easily peeled off from the topcoat layer when in use. Furthermore, printing can be applied to the topcoat layer. [Brief explanation of the drawing]

[0024] [Figure 1] This is a cross-sectional view showing one embodiment of the release paper of the present invention. [Figure 2] This is a cross-sectional view showing one embodiment of the thermal recording body of the present invention. [Modes for carrying out the invention]

[0025] [Release paper] The release paper of the present invention comprises at least a paper substrate and a release layer (release treatment layer) provided on the paper substrate. Specifically, it is preferable that the release paper of the present invention comprises a paper substrate and the release layer formed on at least one surface of the paper substrate. The paper substrate functions as a support for the release layer, which increases the strength of the release paper of the present invention and improves handling.

[0026] Hereinafter, one embodiment of the release paper of the present invention will be described in detail with reference to the drawings, but the present invention is not limited to the following embodiments.

[0027] Figure 1 shows one embodiment of the release paper of the present invention. The release paper 1 shown in Figure 1 comprises a paper base material 2 and a release layer 3.

[0028] (Paper base material) Examples of paper substrate 2 include high-quality paper, art paper, coated paper, kraft paper, laminated paper (which is made by laminating these paper substrates with a thermoplastic resin such as polyethylene), and synthetic paper. Paper substrate 2 may be single-layered or multi-layered.

[0029] The thickness of the paper substrate 2 is not particularly limited, but is preferably 5 to 150 μm, and more preferably 10 to 100 μm. When the thickness is within the above range, transparency, coatability, and support properties may be better.

[0030] (Release layer) The release layer 3 adheres moderately to the adhesive surface and can be easily peeled off. Therefore, the release layer 3 functions as a layer to protect the adhesive surface until use.

[0031] The release layer 3 contains at least a vinyl acetate-silicone copolymer resin. The vinyl acetate-silicone copolymer resin functions as a binder in the release layer 3. A commercially available vinyl acetate-silicone copolymer resin can be used.

[0032] The vinyl acetate-silicone copolymer resin described above can be a commercially available product. Preferably, the vinyl acetate-silicone graft copolymer resin is one in which polyvinyl acetate is graft polymerized onto polysiloxane.

[0033] Examples of the vinyl acetate-silicone graft copolymer resins mentioned above include resins obtained by graft copolymerizing vinyl acetate with a polyorganosiloxane having a radically polymerizable carbon-carbon double bond, such as a (meth)acryloyl group. Furthermore, by performing the above graft copolymerization by emulsion polymerization, an emulsion of the vinyl acetate-silicone graft copolymer resin can be obtained, and this emulsion can be used directly as a binder for the topcoat layer 11.

[0034] Examples of the polyorganosiloxanes mentioned above include compounds represented by the following formula (A). [ka]

[0035] (In the above formula (A), R 1 R represents a monovalent hydrocarbon group having 1 to 20 carbon atoms, which is identical or different, substituted or unsubstituted. 2 X represents a mercapto-substituted or (meth)acryloyloxy-substituted C1-C6 alkyl group or vinyl group. X is the same or different substituted or unsubstituted C1-C20 monovalent hydrocarbon group, a substituted or unsubstituted C1-C20 alkoxy group or hydroxyl group, and Y is the same or different X or -[O-Si(X)2] d -X represents a group, where at least two of X and Y are hydroxyl groups. Z represents an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a hydroxyl group. a represents a positive number from 0 to 1000, b represents a positive number from 100 to 10000, c represents a positive number from 1 to 10, and d represents a positive number from 1 to 1000.

[0036] R 1The "monovalent hydrocarbon group having 1 to 20 carbon atoms" in [description] specifically includes alkyl groups such as methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, dodecyl group, tetradecyl group, hexadecyl group, octadecyl group; cycloalkyl groups such as cyclopentyl group, cyclohexyl group, cycloheptyl group; alkenyl groups such as vinyl group, allyl group; aryl groups such as phenyl group, tolyl group, naphthyl group; alkenylaryl groups such as vinylphenyl group; aralkyl groups such as benzyl group, phenylethyl group, phenylpropyl group; alkenylaralkyl groups such as vinylbenzyl group, vinylphenylpropyl group. Examples of the substituent include halogen atoms such as fluorine, bromine, chlorine; (meth)acryloyloxy group, carboxy group, alkoxy group, alkenyloxy group, amino group, alkyl, alkoxy or (meth)acryloyloxy-substituted amino group, etc. R 1 is preferably a methyl group.

[0037] R 2 Among them, a mercaptopropyl group, a (meth)acryloyloxypropyl group, and a vinyl group are preferable.

[0038] The "monovalent hydrocarbon group having 1 to 20 carbon atoms" and the substituent in X are as exemplified and described for R 1 . The "alkoxy group having 1 to 20 carbon atoms" in X specifically includes methoxy group, ethoxy group, propoxy group, butoxy group, hexyloxy group, heptyloxy group, octyloxy group, decyloxy group, tetradecyloxy group, etc. X is preferably a hydroxy group, a methyl group, a butyl group, or a phenyl group.

[0039] Z is preferably an alkyl group having 1 to 4 carbon atoms or a hydroxy group, more preferably a methyl group or a hydroxy group.

[0040] a represents a positive number between 0 and 1000, preferably between 0 and 200. b represents a positive number between 100 and 10000, preferably between 1000 and 5000. c represents a positive number between 1 and 10. d represents a positive number between 1 and 1000, preferably between 1 and 200.

[0041] From the viewpoint of having crosslinkability, the compound represented by formula (A) above preferably has at least two, preferably two to four, hydroxyl groups in one molecule, and preferably has hydroxyl groups at both ends.

[0042] The compound represented by formula (A) above may be a commercially available product or may be synthesized. When synthesized, it can be carried out by a known emulsion polymerization method, and can be synthesized by polymerizing one or more selected from the group consisting of cyclic organosiloxanes, α,ω-dihydroxysiloxane oligomers, α,ω-dialkoxysiloxane oligomers, and alkoxysilanes with a silane coupling agent having a radically polymerizable carbon-carbon double bond using an anionic surfactant.

[0043] The vinyl acetate-silicone copolymer resin described above may be used by one type only, or by two or more types. In particular, it is preferable that the release layer 3 contains two or more types of vinyl acetate-silicone copolymer resin. By using two or more types of vinyl acetate-silicone copolymer resin, the static friction coefficient and dynamic friction coefficient of the release layer 3 can be easily adjusted.

[0044] When using two or more vinyl acetate-silicone copolymer resins, the difference in static friction coefficients of at least two vinyl acetate-silicone copolymer resins is preferably 0.03 or more, more preferably 0.04 or more, and even more preferably 0.05 or more. When the difference in static friction coefficients is 0.03 or more, the static friction coefficient and dynamic friction coefficient of the release layer 3 can be easily adjusted to the range described later.

[0045] The static and dynamic friction coefficients of the vinyl acetate-silicone copolymer resin described above are measured as follows: A solution or emulsion of the vinyl acetate-silicone copolymer resin is applied to a paper substrate at a coating rate of 1.1 g / m². 2 The material was coated to a certain extent (dry mass), and then dried to form a coating layer. The coated layer was attached to a horizontal board using a commercially available adhesive sheet so that the coating layer was on top. A polystyrene board was then laminated onto the coating layer, and a weight was placed on top of the polystyrene board so that the combined weight of the polystyrene board and the weight reached 418g. The laminate of polystyrene board and weight was moved at 10mm / min on the coating layer, and the static friction coefficient and kinetic friction coefficient of the coating layer surface were measured at this time.

[0046] The release layer 3 may further contain an acrylic resin. The acrylic resin functions as a binder in the release layer 3. By using an acrylic resin in addition to the vinyl acetate-silicone copolymer resin, the static and dynamic friction coefficients of the release layer 3 can be easily adjusted to the range described later.

[0047] Examples of the above-mentioned acrylic resins include carboxyl group-containing acrylic resins. Furthermore, from the viewpoint of heat resistance, the above-mentioned acrylic resin is preferably a so-called core-type resin. In this specification, "core-type resin" refers to a resin with a structure in which the shell polymer is removed from the core-shell type resin described later, but unlike so-called general-purpose resin emulsions, the resin does not completely melt even after coating and drying, and remains in particulate form within the layer. As one indicator, the glass transition temperature of the core portion of a core-type resin is usually 50°C or higher. Core-type particles do not easily disintegrate and are resins that easily maintain the shape of the particles, and can form a release layer with high strength.

[0048] The release layer 3 may contain a binder resin other than the vinyl acetate-silicone copolymer resin and the acrylic resin. The content of the vinyl acetate-silicone copolymer resin and / or the acrylic resin in the release layer 3 is preferably 60% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, and may be 95% by mass or more or 98% by mass or more, based on the total amount of binder (100% by mass).

[0049] The content of the vinyl acetate-silicone copolymer resin in the release layer 3 is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more, relative to the total amount of the binder (100% by mass), and may also be 60% by mass or more, or 70% by mass or more. Furthermore, the above content may be 100% by mass, or 95% by mass or less, 80% by mass or less, 40% by mass or less, or 30% by mass or less.

[0050] If the release layer 3 contains the above-mentioned acrylic resin, the content of the above-mentioned acrylic resin in the release layer 3 is preferably 5% by mass or more, and may be 10% by mass or more, 15% by mass or more, 20% by mass or more, or 70% by mass or more, based on the total amount of the above-mentioned binder (100% by mass). Furthermore, the above content is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less, and may be 40% by mass or less or 30% by mass or less.

[0051] The release layer 3 may further contain a crosslinking agent, a surfactant, an antifoaming agent, etc. Each of these components may be used individually or in combination of two or more. The content of the binder in the release layer 3 is preferably 60% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, relative to the total amount of the release layer 3 (100% by mass). It may also be 95% by mass or more, or 98% by mass or more.

[0052] The coating amount (dry mass) of the release layer 3 is, for example, preferably 0.3 to 10 g / m². 2And more preferably 0.5~5.0 g / m 2 The thickness of the release layer 3 is, for example, preferably 0.3 to 20 μm, and more preferably 0.5 to 5.0 μm. When the amount and thickness of the release layer 3 are within the above range, it is preferable from the viewpoint that the resulting release paper 1 has better peelability.

[0053] The coefficient of dynamic friction of the surface of the release layer 3 is 0.30 or less, and may be 0.27 or less, 0.25 or less, or 0.23 or less. When the coefficient of dynamic friction is 0.30 or less, the surface of the release layer 3 has excellent peelability. Furthermore, from the viewpoint of having better printability of the surface of the release layer 3, the coefficient of dynamic friction is preferably 0.11 or more, and may be 0.14 or more or 0.18 or more.

[0054] The static friction coefficient of the surface of the release layer 3 is 0.19 or higher, and may be 0.20 or higher, 0.25 or higher, or 0.30 or higher. When the static friction coefficient is 0.19 or higher, the printability of the surface of the release layer 3 is excellent. Furthermore, from the viewpoint of having better peelability of the surface of the release layer 3, the static friction coefficient is preferably 0.52 or lower, and may be 0.50 or lower or 0.45 or lower.

[0055] The dynamic and static friction coefficients of the surface of the release layer 3 are measured as follows: The release paper is attached to a horizontal board using a commercially available adhesive sheet so that the release layer is on top. Then, a polystyrene board is laminated onto the coating layer, and a weight is placed on top of the polystyrene board so that the total weight of the polystyrene board and weight is 418g. The laminate of polystyrene board and weight is moved on the coating layer at 10mm / min, and the static and dynamic friction coefficients of the surface of the coating layer are measured at this time.

[0056] The release layer 3 is placed on adhesive paper with an acrylic adhesive that conforms to JIS Z0237 (2009) and has an adhesive strength of 0.40 ± 0.15 N / 10 mm (standard value), and the adhesive is applied at 10 kg / cm². 2The peel strength when T-shaped peeling is performed under conditions of a temperature of 23°C and a peeling speed of 300 mm / min after pressing with a load for 10 minutes is preferably 1100 mN / 50 mm or less, more preferably 1000 mN / 50 mm or less, and even more preferably 800 mN / 50 mm or less. When the above peel strength is 1100 mN / 50 mm or less, the peeling performance of the surface of the release layer 3 is excellent. The above peel strength can be specifically measured by the method described in the examples.

[0057] [How to manufacture release paper] The release paper of the present invention can be manufactured by known or conventional methods. For example, a method for manufacturing the release paper 1 shown in Figure 1 will be described. First, a coating for forming the release layer 3 is prepared by a conventional method.

[0058] (Preparation process) The method for preparing the above coating solution is not particularly limited, and for example, it can be prepared by pre-dispersing all the materials used in the release layer 3 in the same solvent. Examples of methods for preparing the coating solution that forms the release layer include stirring, ultrasonic treatment, crushing treatment using a ball mill, bead mill, sand mill, high-pressure homogenizer, etc. One of these methods may be used, or two or more may be used.

[0059] (Coating process) The prepared release layer coating solution is applied directly to the paper substrate. Examples of application methods include those exemplified and described in the above-mentioned method for manufacturing a thermal recording body. These methods may be used individually or in combination of two or more.

[0060] (drying process) The method for drying the above-mentioned coating liquid is not particularly limited and includes, for example, heat drying, room temperature drying, and vacuum drying. One of these methods may be used, or two or more may be used.

[0061] In this manner, a release layer 3 can be formed on one side of the paper substrate 2 to manufacture release paper 1.

[0062] The release paper of the present invention is printable on the release layer. Therefore, the adhesive layer can be protected until use, it can be easily peeled off from the release layer when in use, and printing can be applied to the release layer.

[0063] [Thermal recording media] The thermal recording body of the present invention has a structure in which a thermal recording layer and a topcoat layer are laminated. The topcoat layer is located on one surface of the thermal recording body of the present invention. The thermal recording body of the present invention may also include other layers besides the thermal recording layer and the topcoat layer. Examples of these other layers include an undercoat layer, a backcoat layer, an adhesive layer, and an intermediate layer. The undercoat layer is a layer provided between the substrate and the thermal recording layer, and can improve the anchoring ability of the thermal recording layer to the substrate. The intermediate layer is a layer located between the thermal recording layer and the topcoat layer, and an example of an intermediate layer is a protective layer that protects the thermal recording layer. The backcoat layer is a layer provided on the surface of the substrate opposite to the surface on which the thermal recording layer is provided.

[0064] The thermal recording body of the present invention preferably comprises a substrate as one of the other layers. The substrate functions as a support for the thermal recording layer and the top coat layer, thereby increasing the strength of the thermal recording body of the present invention and providing excellent handling properties. The thermal recording body of the present invention comprising the substrate preferably has a structure in which the substrate, the thermal recording layer, and the top coat layer are laminated in this order.

[0065] The thermal recording body of the present invention preferably comprises an adhesive layer as one of the other layers. By providing the adhesive layer on the surface of the thermal recording body of the present invention (the surface opposite to the top coat layer), it can be made into a tack label (sticker) that can be attached to an object. The thermal recording body of the present invention comprising an adhesive layer preferably has a structure in which the adhesive layer, the thermal recording layer, and the top coat layer are laminated in this order.

[0066] Hereinafter, one embodiment of the thermal recording body of the present invention will be described in detail with reference to the drawings, but the present invention is not limited to the following embodiments.

[0067] Figure 2 shows one embodiment of the thermal recording body of the present invention. The thermal recording body 4 shown in Figure 2 comprises, in this order, an adhesive layer 5, a back coat layer 6, a substrate 7, an undercoat layer 8, a thermal recording layer 9, an intermediate layer 10, and a top coat layer 11. The top coat layer 11 is located on one surface of the thermal recording body 4, and the adhesive layer 5 is located on the other surface of the thermal recording body 4. The elongated thermal recording body 4 can be wound into a wound body by winding it so that the surface of the adhesive layer 5 overlaps the surface of the top coat layer 11. In this case, a release paper to protect the surface of the adhesive layer 5 until use is not required. However, a release paper to protect the surface of the adhesive layer 5 until use may be attached to the surface of the adhesive layer 5 of the thermal recording body 4. In addition, the thermal recording body 4 shown in Figure 2 does not necessarily have to include one or more layers selected from the group consisting of the adhesive layer 5, back coat layer 6, substrate 7, undercoat layer 8, and intermediate layer 9.

[0068] (base material) The base material 7 is preferably a paper base material. Examples of the paper base material include those exemplified and described above as paper base materials in the release paper. The base material 7 may be a single layer or a multi-layered layer.

[0069] The thickness of the substrate 7 is not particularly limited, but is preferably 5 to 150 μm, and more preferably 10 to 100 μm. When the thickness is within the above range, transparency, coatability, and supportability may be better.

[0070] (Undercoat layer) The undercoat layer 8 is a layer intended to improve the adhesion between the substrate 7 and the thermal recording layer 9. The undercoat layer 8 may be omitted if it is not necessary, in which case the thermal recording layer 9 can be directly laminated onto the substrate 7. The material used to form the undercoat layer 8 is not particularly limited and can be, for example, a resin. The undercoat layer 8 may also contain other components. Examples of these other components include surfactants, preservatives, inorganic pigments, organic pigments, viscosity modifiers, etc.

[0071] 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; and styrene-butadiene latex (SBR) resin. These resins may also be modified resins obtained by known methods. Only one of the above resins may be used, or two or more may be used.

[0072] In this specification, "acrylic resin" means a resin obtained by homopolymerizing acrylic monomers (monomers having a (meth)acryloyl group) (acrylic resin), and / or a resin obtained by copolymerizing an acrylic monomer with another monomer (a monomer other than an acrylic monomer that can copolymerize with an acrylic monomer). Here, the acrylic monomer and the other monomer may be one type or 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. Also, "(meth)acrylic acid (salt)" means (meth)acrylic acid and / or (meth)acrylic acid salt.

[0073] The salts in the above (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 salt, ethylamine salt, diethylamine salt, and triethylamine salt; polyamine salts such as diethyleneamine salt and diethylenetriamine salt; 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. One type of salt may be used, or two or more types may be used.

[0074] 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.

[0075] Examples of the above-mentioned surfactants include anionic surfactants such as sodium dioctyol succinate, sodium dodecylbenzenesulfonate, sodium lauryl sulfate, and alkyl ether sulfate salts; and nonionic surfactants such as acetylene glycol and alkylene oxide adducts of acetylene glycol. One type of surfactant may be used, or two or more types may be used.

[0076] The coating amount (dry mass) of the undercoat layer 8 is, for example, 0.1 to 5.0 g / m². 2 Preferably, and more preferably, 0.3 to 4.0 g / m 2 More preferably 0.5 to 3.0 g / m² 2 Therefore, when the amount of coating is within the above range, the adhesion between layers becomes more appropriate, and delamination between layers can be further suppressed.

[0077] (Thermal recording layer) The thermal recording layer 9 is a layer that develops color when heated by a thermal head or the like, and forms a recorded image on the thermal recording body 4. The material used to form the thermal recording layer 9 is not particularly limited, and known materials can be used as appropriate. For example, from the viewpoint of producing printing with excellent color development and contrast when heated, the thermal recording layer 9 preferably contains at least a leuco dye and a color developer. The color developer may or may not contain a non-phenolic color developer. From the viewpoint of environmental considerations, it is preferable that the color developer contains a non-phenolic color developer.

[0078] The thermal recording layer 9 may further contain other components as needed. Examples of these other components include binders, fillers, lubricants, dispersants, crosslinking agents, preservatives, sensitizers, surfactants, viscosity modifiers, and the like.

[0079] Examples of the non-phenolic colorants mentioned above include urea compounds. Preferred urea compounds are N,N'-diarylurea derivatives having one or more sulfonic acid ester structures (-S(=O)2-O-) in their molecules. Specifically, the N,N'-diarylurea derivatives preferably include the compound represented by formula (1) and / or the compound represented by formula (2), and more preferably the compound represented by formula (1). In this specification, "urea compound" means a compound having one or more urea bonds (-NH-C(=O)-NH-) in its molecule, and "N,N'-diarylurea derivative" means a compound having an N,N'-diarylurea skeleton.

[0080] [ka] (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 m may be the same or different. m represents an integer between 0 and 4, and multiple m values ​​may be the same or different. [ka] (Each symbol in equation (2) is the same as in equation (1) above.)

[0081] The compound represented by formula (1) and / or the compound represented by formula (2) above can react with, for example, a leuco dye described later, upon heating to produce a color.

[0082] In equations (1) and (2) above, 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 m may be the same or different. m represents an integer from 0 to 4, and multiple values ​​of m, when m is 2 or greater, may be the same or different.

[0083] In the above equation (1), multiple R 1 -SO3- is directly bonded to the carbon atoms that make up the benzene ring. Also, multiple R 1 The substitution position of -SO3- may be the same or different. 1 The substitution site for -SO3- is preferably the 2nd, 3rd, or 4th position, and more preferably the 3rd position.

[0084] In equation (2) above, R 1 -SO3- is directly bonded to the carbon atoms that make up the benzene ring. 1 The substitution site for -SO3- is preferably the 2nd, 3rd, or 4th position, and more preferably the 3rd position.

[0085] In the above equations (1) and (2), the above R 1Examples of the "carbon 1-12 hydrocarbon groups which may have substituents" include, for example, linear alkyl groups with 1-12 carbon atoms, branched alkyl groups with 1-12 carbon atoms, alicyclic alkyl groups with 3-12 carbon atoms, aralkyl groups with 7-12 carbon atoms, and aryl groups with 6-12 carbon atoms. Furthermore, multiple "carbon 1-12 hydrocarbon groups which may have substituents" may be the same or different.

[0086] Examples of the above-mentioned "linear alkyl groups having 1 to 12 carbon atoms, branched alkyl groups having 1 to 12 carbon atoms, and alicyclic alkyl groups having 3 to 12 carbon atoms" include linear alkyl groups having 1 to 12 carbon atoms such as methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, t-butyl group, cyclopentyl group, hexyl group, cyclohexyl group, 2-ethylhexyl group, and lauryl group, branched alkyl groups having 1 to 12 carbon atoms, or alicyclic alkyl groups having 3 to 12 carbon atoms. These alkyl groups may further have substituents as described later.

[0087] Examples of the above-mentioned "aralkyl groups having 7 to 12 carbon atoms" include unsubstituted aralkyl groups such as benzyl group, 1-phenylethyl group, 2-phenylethyl group, and 3-phenylpropyl group. These aralkyl groups may also have substituents as described later. Examples of "aralkyl groups having 7 to 12 carbon atoms with substituents" include aralkyl groups having substituents such as p-methylbenzyl group, m-methylbenzyl group, m-ethylbenzyl group, p-ethylbenzyl group, pi-propylbenzyl group, pt-butylbenzyl group, p-methoxybenzyl group, m-methoxybenzyl group, o-methoxybenzyl group, m,p-di-methoxybenzyl group, p-ethoxy-m-methoxybenzyl group, p-phenylmethylbenzyl group, p-cumylbenzyl group, p-phenylbenzyl group, o-phenylbenzyl group, m-phenylbenzyl group, p-tolylbenzyl group, m-tolylbenzyl group, o-tolylbenzyl group, and p-chlorobenzyl group.

[0088] Examples of the above-mentioned "aryl groups having 6 to 12 carbon atoms" include unsubstituted aryl groups such as phenyl groups, 1-naphthyl groups, and 2-naphthyl groups. These aryl groups may also have substituents as described later. Examples of "substituted aryl groups having 6 to 12 carbon atoms" include substituted aryl groups such as p-tolyl groups, m-tolyl groups, o-tolyl groups, 2,5-dimethylphenyl groups, 2,4-dimethylphenyl groups, 3,5-dimethylphenyl groups, 2,3-dimethylphenyl groups, 3,4-dimethylphenyl groups, mesitylene groups, p-ethylphenyl groups, pi-propylphenyl groups, pt-butylphenyl groups, p-methoxyphenyl groups, 3,4-dimethoxyphenyl groups, p-ethoxyphenyl groups, p-chlorophenyl groups, and t-butylated naphthyl groups.

[0089] The above-mentioned "substituents" are not particularly limited. When the "carbon group having 1 to 12 carbon atoms that may have substituents" is a "linear alkyl group having 1 to 12 carbon atoms or a branched alkyl group having 1 to 12 carbon atoms," examples of substituents include halogen atoms and alkoxy groups. Furthermore, when the "carbon group having 1 to 12 carbon atoms that may have substituents" is an "alicyclic alkyl group having 3 to 12 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, or an aryl group having 6 to 12 carbon atoms," examples of substituents include halogen atoms, alkyl groups, alkoxy groups, and aryl groups. Among these, alkyl groups and alkoxy groups are preferred substituents. Here, the number of carbon atoms in the alkyl and alkoxy groups as substituents is not particularly limited, but C1 to C6 is preferred, and C1 to C4 is more preferred. There may be multiple "substituents" or none at all. The substitution positions of the multiple "substituents" may be the same or different. The substitution position of the above-mentioned "substituent" is preferably one of the 2nd, 3rd, or 4th positions of the aralkyl group or aryl group, and more preferably the 4th position.

[0090] In the above equations (1) and (2), the above R 1The R is preferably an unsubstituted or substituted aryl group having 6 to 12 carbon atoms. More specifically, the above R 1 The R is preferably a phenyl group, a p-tolyl group, an m-tolyl group, an o-tolyl group, a 2,5-dimethylphenyl group, a 2,4-dimethylphenyl group, a 3,5-dimethylphenyl group, a 2,3-dimethylphenyl group, or a 3,4-dimethylphenyl group, with the p-tolyl group being more preferred. 1 In that case, the sensitivity will be better.

[0091] In the above formulas (1) and (2), A 1 is a carbon atom that constitutes a benzene ring, and the above R 1 -SO3- can bond to carbon atoms that are not bonded. Also, multiple A 1 The substitution positions may be the same or different. (See A above) 1 The preferred substitution positions are the 2nd, 3rd, and 4th positions.

[0092] In formulas (1) and (2) above, m is preferably an integer between 0 and 2, more preferably an integer between 0 and 1, and even more preferably 0.

[0093] A above 1 Examples of hydrocarbon groups having 1 to 4 carbon atoms include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, and t-butyl groups.

[0094] The compounds represented by formula (1) above include, but are not limited to, the following specific compounds.

[0095] That is, 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, N,N'-di-[3-(m-xylenesulfonyloxy)phenyl N,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, N,N'-di-[3-(benzenesulfonyloxy)-4-propylphenyl]urea,

[0096] N,N'-di-[3-(p-ethylbenzenesulfonyloxy)phenyl]urea, N,N'-di-[3-(p-propylbenzenesulfonyloxy)phenyl]urea, N,N'-di-[3-(p-isopropylbenzenesulfonyloxy)phenyl]urea, N,N'-di-[3-(pt-butylbenzenesulfonyloxy)phenyl]urea, N,N'-di-[3-(p-methoxybenzenesulfonyloxy)phenyl]urea, N,N'-di-[3-(m-methoxybenzenesulfonyloxy)phenyl]urea, N,N'-di-[3-(o-methoxybenzenesulfonyloxy)phenyl]urea,

[0097] N-[3-(benzenesulfonyloxy)phenyl]-N'-[3-(p-toluenesulfonyloxy)phenyl]urea, N-[3-(benzenesulfonyloxy)phenyl]-N'-[3-(m-toluenesulfonyloxy)phenyl]urea, N-[3-(benzenesulfonyloxy)phenyl]-N'-[3-(o-toluenesulfonyloxy)phenyl]urea, N-[3-(benzenesulfonyloxy)phenyl]-N'-[3-(p-xylenesulfonyloxy)phenyl]urea, N-[3-(benzenesulfonyloxy)phenyl] [Nyl]-N'-[3-(mesitylenesulfonyloxy)phenyl]urea, N-[3-(benzenesulfonyloxy)phenyl]-N'-[3-(1-naphthalenesulfonyloxy)phenyl]urea, N-[3-(benzenesulfonyloxy)phenyl]-N'-[3-(2-naphthalenesulfonyloxy)phenyl]urea, N-[3-(benzenesulfonyloxy)phenyl]-N'-[3-(p-ethylbenzenesulfonyloxy)phenyl]urea, N-[3-(benzenesulfonyloxy)phenyl]-N'-[3-(p-methoxy] [Benzenesulfonyloxy)phenyl]urea, N-[3-(benzenesulfonyloxy)phenyl]-N'-[3-(benzylsulfonyloxy)phenyl]urea, N-[3-(benzenesulfonyloxy)phenyl]-N'-[3-(ethanesulfonyloxy)phenyl]urea, N-[3-(benzenesulfonyloxy)phenyl]-N'-[3-(benzenesulfonyloxy)-4-methylphenyl]urea, N-[3-(p-toluenesulfonyloxy)phenyl]-N'-[3-(m-toluenesulfonyloxy)phenyl]urea , N-[3-(p-toluenesulfonyloxy)phenyl]-N'-[3-(o-toluenesulfonyloxy)phenyl]urea, N-[3-(p-toluenesulfonyloxy)phenyl]-N'-[3-(p-toluenesulfonyloxy)-4-methylphenyl]urea, N-[3-(p-toluenesulfonyloxy)phenyl]-N'-[3-(p-ethylbenzenesulfonyloxy)phenyl]urea, N-[3-(p-toluenesulfonyloxy)phenyl]-N'-[3-(p-methoxybenzenesulfonyloxy)phenyl]urea,

[0098] N-[3-(p-toluenesulfonyloxy)phenyl]-N'-[3-(benzylsulfonyloxy)phenyl]urea, N-[3-(p-toluenesulfonyloxy)phenyl]-N'-[3-(p-methylbenzylsulfonyloxy)phenyl]urea, N-[3-(p-toluenesulfonyloxy)phenyl]-N'-[3-(p-methoxybenzylsulfonyloxy)phenyl]urea,

[0099] N,N'-di-[4-(benzenesulfonyloxy)phenyl]urea, N,N'-di-[4-(benzenesulfonyloxy)-3-methylphenyl]urea, N,N'-di-[4-(benzenesulfonyloxy)-3-ethylphenyl]urea, N,N'-di-[4-(benzenesulfonyloxy)-3-propylphenyl]urea, N,N'-di-[4-(benzenesulfonyloxy)-3-t-butylphenyl]urea,

[0100] N-[4-(benzenesulfonyloxy)phenyl]-N'-[4-(p-toluenesulfonyloxy)phenyl]urea, N-[4-(benzenesulfonyloxy)phenyl]-N'-[4-(m-toluenesulfonyloxy)phenyl]urea, N-[4-(benzenesulfonyloxy)phenyl]-N'-[4-(o-toluenesulfonyloxy)phenyl]urea, N-[4-(benzenesulfonyloxy)phenyl]-N'-[4-(p-xylenesulfonyloxy)phenyl]urea, N-[4-(benzenesulfonyloxy) [phenyl]-N'-[4-(mesitylenesulfonyloxy)phenyl]urea, N-[4-(benzenesulfonyloxy)phenyl]-N'-[4-(1-naphthalenesulfonyloxy)phenyl]urea, N-[4-(benzenesulfonyloxy)phenyl]-N'-[4-(2-naphthalenesulfonyloxy)phenyl]urea, N-[4-(benzenesulfonyloxy)phenyl]-N'-[4-(p-ethylbenzenesulfonyloxy)phenyl]urea, N-[4-(benzenesulfonyloxy)phenyl]-N'-[4-(p- [methoxybenzenesulfonyloxy)phenyl]urea, N-[4-(benzenesulfonyloxy)phenyl]-N'-[4-(benzylsulfonyloxy)phenyl]urea, N-[4-(benzenesulfonyloxy)phenyl]-N'-[4-(ethanesulfonyloxy)phenyl]urea, N-[4-(p-toluenesulfonyloxy)phenyl]-N'-[4-(m-toluenesulfonyloxy)phenyl]urea, N-[4-(p-toluenesulfonyloxy)phenyl]-N'-[4-(o-toluenesulfonyloxy)phenyl N-[4-(p-toluenesulfonyloxy)phenyl]-N'-[4-(p-ethylbenzenesulfonyloxy)phenyl]urea, N-[4-(p-toluenesulfonyloxy)phenyl]-N'-[4-(p-methoxybenzenesulfonyloxy)phenyl]urea, N-[4-(p-toluenesulfonyloxy)phenyl]-N'-[4-(2-naphthalenesulfonyloxy)phenyl]urea, N-[4-(p-toluenesulfonyloxy)phenyl]-N'-[4-(benzylsulfonyloxy)phenyl]urea,N-[4-(p-toluenesulfonyloxy)phenyl]-N'-[4-(p-methylbenzylsulfonyloxy)phenyl]urea, N-[4-(p-toluenesulfonyloxy)phenyl]-N'-[4-(p-methoxybenzylsulfonyloxy)phenyl]urea,

[0101] N,N'-di-[4-(benzylsulfonyloxy)phenyl]urea, N,N'-di-[4-(benzylsulfonyloxy)-3-methylphenyl]urea, N,N'-di-[4-(phenylethanesulfonyloxy)phenyl]urea, N,N'-di-[4-(phenylpropanesulfonyloxy)phenyl]urea, N,N'-di-[4-(p-methoxybenzylsulfonyloxy)phenyl)urea,

[0102] N,N'-di-[2-(benzenesulfonyloxy)phenyl]urea, N,N'-di-[2-(benzenesulfonyloxy)-4-methylphenyl]urea, N,N'-di-[2-(benzenesulfonyloxy)-4-ethylphenyl]urea, N,N'-di-[2-(benzenesulfonyloxy)-5-methylphenyl]urea, N,N'-di-[2-(benzenesulfonyloxy)-4-propylphenyl]urea,

[0103] N,N'-di-[2-(o-toluenesulfonyloxy)phenyl]urea, N,N'-di-[2-(m-toluenesulfonyloxy)phenyl]urea, N,N'-di-[2-(p-toluenesulfonyloxy)phenyl]urea, N,N'-di-[2-(p-toluenesulfonyloxy)-4-methylphenyl]urea,

[0104] Examples include N,N'-di-[2-(p-xylenesulfonyloxy)phenyl]urea, N,N'-di-[2-(m-xylenesulfonyloxy)phenyl]urea, and N,N'-di-[2-(mesitylenesulfonyloxy)phenyl]urea. Among these, N,N'-di-[3-(p-toluenesulfonyloxy)phenyl]urea is particularly preferred as the compound represented by formula (1) above, from the viewpoint that it can achieve good color development upon heating and also has excellent resistance to humid heat.

[0105] Furthermore, the compounds represented by formula (2) above include, but are not limited to, the following specific compounds.

[0106] That is, the compounds represented by the above formula (2) are 3-[(3-phenylureido)phenyl]-4-methylbenzenesulfonate, 4-[(3-phenylureido)phenyl]-4-methylbenzenesulfonate, 2-[(3-phenylureido)phenyl]-4-methylbenzenesulfonate, 3-[(3-phenylureido)phenyl]-2-methylbenzenesulfonate, 4-[(3-phenylureido)phenyl]-2-methylbenzenesulfonate, 2-[(3-phenylureido)phenyl [L]-2-methylbenzenesulfonate, 3-[(3-phenylureido)phenyl]-3-methylbenzenesulfonate, 4-[(3-phenylureido)phenyl]-3-methylbenzenesulfonate, 2-[(3-phenylureido)phenyl]-3-methylbenzenesulfonate, 3-[(3-phenylureido)phenyl]-benzenesulfonate, 4-[(3-phenylureido)phenyl]-benzenesulfonate, 2-[(3-phenylureido)phenyl]-benzenesulfonate,

[0107] 3-[3-(4-methylphenylureido)]phenyl-4-methylbenzenesulfonate, 4-[3-(4-methylphenylureido)]phenyl-4-methylbenzenesulfonate, 2-[3-(4-methylphenylureido)]phenyl-4-methylbenzenesulfonate, 3-[3-(4-methylphenylureido)]phenyl-2-methylbenzenesulfonate, 4-[3-(4-methylphenylureido)]phenyl-2-methylbenzenesulfonate, 2-[3-(4-methylphenylureido)]phenyl-2-methylbenzenesulfonate Phenyl-3-methylbenzenesulfonate, 3-[3-(4-methylphenylureido)]phenyl-3-methylbenzenesulfonate, 4-[3-(4-methylphenylureido)]phenyl-3-methylbenzenesulfonate, 2-[3-(4-methylphenylureido)]phenyl-3-methylbenzenesulfonate, 3-[3-(4-methylphenylureido)]phenyl-benzenesulfonate, 4-[3-(4-methylphenylureido)]phenyl-benzenesulfonate, 2-[3-(4-methylphenylureido)]phenyl-benzenesulfonate,

[0108] 3-[3-(2-methylphenylureido)]phenyl-4-methylbenzenesulfonate, 4-[3-(2-methylphenylureido)]phenyl-4-methylbenzenesulfonate, 2-[3-(2-methylphenylureido)]phenyl-4-methylbenzenesulfonate, 3-[3-(2-methylphenylureido)]phenyl-2-methylbenzenesulfonate, 4-[3-(2-methylphenylureido)]phenyl-2-methylbenzenesulfonate, 2-[3-(2-methylphenylureido)]phenyl-2-methylbenzenesulfonate Phenyl-3-methylbenzenesulfonate, 3-[3-(2-methylphenylureido)]phenyl-3-methylbenzenesulfonate, 4-[3-(2-methylphenylureido)]phenyl-3-methylbenzenesulfonate, 2-[3-(2-methylphenylureido)]phenyl-3-methylbenzenesulfonate, 3-[3-(2-methylphenylureido)]phenyl-benzenesulfonate, 4-[3-(2-methylphenylureido)]phenyl-benzenesulfonate, 2-[3-(2-methylphenylureido)]phenyl-benzenesulfonate,

[0109] 3-[3-(3-methylphenylureido)]phenyl-4-methylbenzenesulfonate, 4-[3-(3-methylphenylureido)]phenyl-4-methylbenzenesulfonate, 2-[3-(3-methylphenylureido)]phenyl-4-methylbenzenesulfonate, 3-[3-(3-methylphenylureido)]phenyl-2-methylbenzenesulfonate, 4-[3-(3-methylphenylureido)]phenyl-2-methylbenzenesulfonate, 2-[3-(3-methylphenylureido)]phenyl-2-methylbenzenesulfonate Phenyl-3-methylbenzenesulfonate, 3-[3-(3-methylphenylureido)]phenyl-3-methylbenzenesulfonate, 4-[3-(3-methylphenylureido)]phenyl-3-methylbenzenesulfonate, 2-[3-(3-methylphenylureido)]phenyl-3-methylbenzenesulfonate, 3-[3-(3-methylphenylureido)]phenyl-benzenesulfonate, 4-[3-(3-methylphenylureido)]phenyl-benzenesulfonate, 2-[3-(3-methylphenylureido)]phenyl-benzenesulfonate,

[0110] Examples include 3-(3-phenylureido)phenyl-4-propyloxybenzenesulfonate, 4-(3-phenylureido)phenyl-4-propyloxybenzenesulfonate, 2-(3-phenylureido)phenyl-4-propyloxybenzenesulfonate, 3-(3-phenylureido)phenyl-4-phenyloxybenzenesulfonate, 4-(3-phenylureido)phenyl-4-phenyloxybenzenesulfonate, and 2-(3-phenylureido)phenyl-4-phenyloxybenzenesulfonate. Among these, 3-[(3-phenylureido)phenyl]-4-methylbenzenesulfonate is particularly preferred as the compound represented by formula (2) above, from the viewpoint that it can achieve good color development upon heating and can also have excellent resistance to humid heat.

[0111] 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). Similarly, 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). Furthermore, the above-mentioned color developer may contain both the compound represented by formula (1) and the compound represented by formula (2).

[0112] The above-mentioned color developer may also contain other color developers (other color developers) as long as they do not impair the effects of the present invention.

[0113] Other color developers mentioned above include, for example, known non-phenol color developers such as 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'-bis[(4-methyl-3-phenoxycarbonylaminophenyl)ureido]diphenylsulfone (trade name: UU), 4,4'-isopropylidenediphenol (BPA), and 4,4'-dihydroxydiphenyl Known color developers include sulfone (BPS), 4-allyloxy-4'-hydroxydiphenylsulfone (trade name: BPS-MAE), 4-allyloxy-4'-hydroxy-diphenylsulfone (trade name: TGSA), 4-hydroxy-4'-propoxydiphenylsulfone, 4-hydroxy-4'-isopropoxysulfone (trade name: D-8), N-(m-tolylaminocarbonyl)-methionine, N-(m-tolylaminocarbonyl)-phenylalanine, and N-(phenylaminocarbonyl)-phenylalanine.

[0114] Furthermore, other color developers include, for example, 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, and α-{4-[(4-hydroxyphenyl)sulfonyl]phenyl}-ω-hydroxypoly(degree of polymerization n=1~7)(oxyethyleneoxyethylene) Examples include xy-p-phenylenesulfonyl-p-phenylene, 3,5-bis(α-methylbenzyl)salicylic acid, bis[4-(n-octyloxycarbonylamino)zinc salicylate], 4,4'-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-(1-methylethoxy)phenyl]sulfonylphenoxy]butoxy]phenyl]sulfonyl]phenol, and 4-tert-butylphenol-formaldehyde polycondensate.

[0115] 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 9. When the above-mentioned content is 10% by mass or more, the sensitivity can be further improved. Furthermore, the content of the above-mentioned color developer 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 thermal recording layer 9.

[0116] When the thermal recording layer 9 contains a non-phenolic developer, the content of the non-phenolic developer is preferably 50% by mass or more, more preferably 60% by mass or more, 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 the developer in the thermal recording layer 9. It may also be 100% by mass. When the above content is within the above range, the environmental burden can be further suppressed. Furthermore, the total content of the compound represented by formula (1) and / or the compound represented by formula (2) is preferably within the above range based on 100% by mass of the total amount of the developer in the thermal recording layer 9.

[0117] The melting point of the above-mentioned color developer is not particularly limited, but is preferably 130°C or higher, more preferably 140°C or higher, and even more preferably 150°C or higher. Furthermore, the melting point of the above-mentioned color developer is preferably 195°C or lower, and more preferably 185°C or lower. The melting point of the above-mentioned non-phenolic color developer is also preferably within the above range. When the melting point is within the above range, the sensitivity to heating can be adjusted to a more appropriate range, improving printability with a thermal head, and also providing excellent heat resistance and moisture resistance.

[0118] The above leuco dyes are not particularly limited, and for example, 2'-bromo-6'-(dibutylamino)-3'-methylspiro[isobenzofuran-1(3H),9'-[9H]xanthene]-3-one, 3-(1-ethyl-2-methylindole-3-yl)-3-(4-diethylamino-2-methylphenyl)-4-azaphthalide, 6-(dimethylamino)-3,3-bis[4-(dimethylamino)phenyl]-1(3H)-isobenzofuranone, 1,2-dihydro-1-ethyl-8-[N-(4-methylphenyl)-N-ethylamino]-2,2,4-trimethylspiro[11H]-chromeno(2,3-g)quinoline-11,3'-phthalide, 2'-[bis(phenylmethyl)amino]-6'-(diethylamino)-spiro[isobenzofuran-1(3H),9'-(9H)xanthene]-3-one, 3-(N-isobutyl-N-ethyl)amino-6-methyl-7-anilinofluorane, 3-(N-isopentyl-N-ethyl)amino-6-methyl-7-o-chloroanilinofluorane, 3-(N-methyl-Np-toluidino)-6-methyl-7-anilinofluorane, 3-(N-ethyl-Np-toluidino)-6-methyl-7-anilinofluoro Lan, 3-(N-ethyl-N-isopentyl)amino-6-methyl-7-anilinofluorane, 3-(N-ethoxypropyl-N-ethyl)amino-6-methyl-7-anilinofluorane, 3-(N-cyclohexyl-N-methyl)amino-6-methyl-7-anilinofluorane, 3-(N-methyl-Nn-propyl)amino-6-methyl-7-anilinofluorane, 3-dibutylamino- Examples include 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, 3-diethylamino-7-chlorofluorane, 3-dibutylamino-6-methyl-7-bromofluorane, 3-dibutylamino-7-(o-chloroanilino)fluorane, 3-dipentylamino-6-methyl-7-anilinofluorane, 3-dimethylamino-5-methyl-7-methylfluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, and crystal violet lactone. The above leuco dyes may be used individually or in combination of two or more types.

[0119] The average particle size of the leuco dye described above is not particularly limited, but is preferably 0.1 to 1.0 μm. Generally, since leuco dyes react by melting, the reaction slows down as the average particle size increases, and the sensitivity characteristics decrease. On the other hand, as the average particle size decreases, the risk of unexpected color development due to heat during drying of the coating solution increases. By keeping the average particle size of the leuco dye within the above range, the sensitivity characteristics and color development temperature of the leuco dye can be appropriately adjusted. In this specification, the average particle size refers to the particle size at 50% of the cumulative value in the particle size distribution measured by the laser diffraction-scattering method (D50, median diameter). The average particle size by the laser diffraction-scattering method can be measured using a laser diffraction-scattering particle size distribution analyzer (for example, Microtrac-Bell, device name: MT3300EX-II).

[0120] The content of the above leuco 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 solids content of the thermal recording layer 9. When the above content is 5% by mass or more, the sensitivity can be further improved. Furthermore, the content of the above leuco dye is preferably 40% by mass or less, and more preferably 30% by mass or less, based on 100% by mass of the total solids content of the thermal recording layer 9.

[0121] Examples of the binders mentioned above include acrylic resins such as acrylic resins, styrene-acrylic resins, acrylic-urethane resins, acrylamide resins, and vinyl acetate-acrylic resins; maleic acid resins such as maleic acid resins, styrene-maleic acid resins, and olefin-maleic acid resins; and resins such as styrene-butadiene latex (SBR) resin. These resins may be modified resins obtained by known methods. Other examples include starch, casein, gelatin, polyamide, polyacrylamide, modified 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, and methyl vinyl ether. The above-mentioned binders may be used individually or in combination of two or more types.

[0122] The content of the above-mentioned binder is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 20% by mass or more, and particularly preferably 25% by mass or more, based on 100% by mass of the total solid content of the thermal recording layer 9. Furthermore, the content of the above-mentioned binder is preferably 60% by mass or less, and more preferably 50% by mass or less, based on 100% by mass of the total solid content of the thermal recording layer 9.

[0123] 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 metal soaps such as zinc stearate. One or more of the above lubricants may be used.

[0124] 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 9. Furthermore, the content of the above lubricant is preferably 10% by mass or less, and more preferably 5% by mass or less, based on 100% by mass of the total solid content of the thermal recording layer 9.

[0125] Examples of the above dispersants include anionic surfactants such as sodium dialkyl sulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl sulfate, and alkyl ether sulfate salts; nonionic surfactants such as acetylene glycol and alkylene oxide adducts of acetylene glycol; polyvinyl alcohols such as fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, and sulfonic acid-modified polyvinyl alcohol; and polymeric dispersants such as styrene-acrylic copolymers and acrylic resins. One or more of the above dispersants may be used.

[0126] The content of the above dispersant is preferably 0.1% by mass or more, more preferably 1% 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 thermal recording layer 9. Furthermore, the content of the above dispersant is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less, based on 100% by mass of the total solid content of the thermal recording layer 9.

[0127] Examples of the above-mentioned fillers include inorganic fillers such as aluminum hydroxide, magnesium hydroxide, aluminum oxide, magnesium oxide, aluminum silicate, calcium carbonate, magnesium carbonate, barium sulfate, silica gel, activated clay, talc, clay, kaolin, calcined kaolin, diatomaceous earth, white carbon, silicon dioxide, silica, colloidal silica, and titanium dioxide; and organic fillers such as styrene-acrylic resin particles, polystyrene resin particles, urea-formaldehyde resin particles, and polyolefin resin particles. One type of filler may be used, or two or more types may be used.

[0128] The content of the above-mentioned filler is preferably 0.1% by mass or more, more preferably 1% 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 thermal recording layer 9. Furthermore, the content of the above-mentioned filler is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less, based on 100% by mass of the total solid content of the thermal recording layer 9.

[0129] Examples of the above crosslinking agents include organic crosslinking agents such as cationic crosslinking agents and non-cationic crosslinking agents; and inorganic crosslinking agents such as zirconium carbonate. Examples of the above cationic crosslinking agents include epichlorohydrin resins such as polyamide epichlorohydrin resins, polyamine epichlorohydrin resins, and polyamide polyamine epichlorohydrin resins. Examples of the above non-cationic crosslinking agents include oxazoline compounds such as oxazoline group-containing polymers and oxazoline group-containing low molecular weight compounds. One type of the above crosslinking agent may be used, or two or more types may be used.

[0130] 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 thermal recording layer 9. 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 thermal recording layer 9.

[0131] The coating amount (dry mass) of the thermal recording layer 9 is, for example, 0.3 to 10 g / m². 2 Preferably, and more preferably, 2.5 to 6.5 g / m 2 Therefore, if the amount of coating is within the above range, the color development of the resulting thermal recording medium 4 can be made more appropriate.

[0132] (Middle class) The intermediate layer 10 is a layer intended to further improve the printability (moisture and heat resistance, etc.) of the thermal recording body 4 by suppressing adverse effects such as the migration of external factors such as chemicals to the thermal recording layer 9 and the resulting decrease in color density. It also has the function of improving the printability (moisture and heat resistance, etc.) by suppressing the migration of oil-soluble components, etc., in layers laminated on the intermediate layer 10, such as the top coat layer 11, to the thermal recording layer 9.

[0133] The intermediate layer 10 can be formed mainly from a resin. The resin is not particularly limited, but it is preferable that it contains a resin having a water-soluble portion. The intermediate layer 10 may further contain other components as needed. Examples of these other components include crosslinking agents, surfactants, preservatives, inorganic pigments, organic pigments, etc. Among these, it is preferable that the intermediate layer 10 contains a crosslinking agent. When the intermediate layer 10 contains a resin having a water-soluble portion, the water-soluble portion can more effectively suppress the migration of oil-soluble components, etc. Furthermore, when the intermediate layer 10 contains a crosslinking agent, a dense crosslinked structure can be formed within the intermediate layer 10, so the crosslinked structure can more effectively suppress the migration of oil-soluble components, etc.

[0134] Examples of resins having the water-soluble portion include hydroxyl group-containing resins such as polyvinyl alcohol (PVA) resin having hydroxyl groups, and carboxyl group-containing resins such as acrylic resin having carboxyl groups. Among these, carboxyl group-containing resins are preferred for the water-soluble portion. Because carboxyl groups are highly hydrophilic functional groups, they are particularly effective in suppressing the migration of oil-soluble components to the heat-sensitive recording layer 9, and are also thought to be able to form a crosslinked structure with the crosslinking agent described later.

[0135] The resin having the water-soluble portion described above is preferably a core-shell type resin. In this specification, "core-shell type resin" means a resin having a structure in which hydrophobic core particles are coated with a water-soluble shell polymer.

[0136] Among the above-mentioned core-shell type resins, a core-shell type resin having a carboxyl group as the water-soluble portion (core-shell type carboxyl group-containing resin) is preferred. Here, the above-mentioned core-shell type carboxyl group-containing resin is considered to contain a carboxyl group in at least the structure of the water-soluble shell polymer.

[0137] Examples of the above-mentioned core-shell type carboxyl group-containing resins include core-shell type acrylic resins such as core-shell type acrylic resins, core-shell type styrene-acrylic resins, core-shell type acrylic-urethane resins, core-shell type acrylamide resins, and core-shell type vinyl acetate-acrylic resins; and core-shell type maleic acid resins. As the above-mentioned core-shell type carboxyl group-containing resin, core-shell type acrylic resins are preferred, and among these, at least one selected from the group consisting of core-shell type acrylic resins, core-shell type styrene-acrylic resins, and core-shell type acrylic-urethane resins is more preferred, and at least one selected from the group consisting of core-shell type acrylic resins and core-shell type styrene-acrylic resins is even more preferred. Examples of the above-mentioned core-shell type acrylic resins include resins that are commercially available under the name Barrier Star (manufactured by Mitsui Chemicals, Inc.).

[0138] Other examples of the above-mentioned resins include SBR resin.

[0139] The resin content is preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more, based on 100% by mass of the total solids content of the intermediate layer 10. Furthermore, the resin content may be 99% by mass or less, or 95% by mass or less, based on 100% by mass of the total solids content of the intermediate layer 10.

[0140] The content of the resin having the water-soluble portion described above is preferably 50% by mass or more, more preferably 60% by mass or more, 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 resin in the intermediate layer 10. It may also be 100% by mass. When the above content is within the above range, the barrier properties of the intermediate layer 10 are further improved, and print retention properties such as humidity and heat resistance may be improved. Furthermore, the content of the core-shell type resin is preferably within the above range based on 100% by mass of the total amount of the above resin in the intermediate layer 10.

[0141] Examples of the crosslinking agents include organic crosslinking agents such as cationic crosslinking agents and non-cationic crosslinking agents; and inorganic crosslinking agents such as zirconium carbonate. Examples of cationic crosslinking agents include epichlorohydrin resins such as polyamide epichlorohydrin resins, polyamine epichlorohydrin resins, and polyamide polyamine epichlorohydrin resins. Examples of non-cationic crosslinking agents include oxazoline compounds such as oxazoline group-containing polymers and oxazoline group-containing low molecular weight compounds. Cationic crosslinking agents are preferred, and polyamide epichlorohydrin resins are more preferred among them. One type of crosslinking agent may be used, or two or more types may be used.

[0142] The content of the above crosslinking agent 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 solids content of the intermediate layer 10. Furthermore, the content of the above crosslinking agent is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less, based on 100% by mass of the total solids content of the intermediate layer 10. When the content is within the above range, an appropriate crosslinked structure can be formed, the barrier properties of the intermediate layer 10 can be further improved, and print retention properties such as moisture and heat resistance can be further improved.

[0143] The coating amount (dry mass) of the intermediate layer 10 is, for example, 0.3 to 10 g / m². 2 Preferably, and more preferably, 1.0 to 4.0 g / m² 2Therefore, if the amount of coating is within the above range, the barrier properties of the resulting thermal recording material 4 can be made more appropriate, and print retention properties such as humidity and heat resistance can be further improved.

[0144] (Top coat layer) The top coat layer 11 functions as a layer that further improves the color development of the thermal recording layer 9 by improving the matching of the thermal recording element 4 with respect to the thermal head.

[0145] The topcoat layer 11 contains at least a vinyl acetate-silicone copolymer resin. The vinyl acetate-silicone copolymer resin functions as a binder in the topcoat layer 11. Examples of the vinyl acetate-silicone copolymer resin include those exemplified and described as the vinyl acetate-silicone copolymer resin contained in the release layer 3. Furthermore, the preferred embodiment of the vinyl acetate-silicone copolymer resin in the topcoat layer 11 is the same as the preferred embodiment of the vinyl acetate-silicone copolymer resin in the release layer 3. The binder may be used by one type only, or by two or more types.

[0146] The vinyl acetate-silicone copolymer resin described above may be used by one type or by two or more types. In particular, the top coat layer 11 preferably contains two or more types of vinyl acetate-silicone copolymer resin. By using two or more types of vinyl acetate-silicone copolymer resin, the static friction coefficient and dynamic friction coefficient of the top coat layer 11 can be easily adjusted.

[0147] When using two or more vinyl acetate-silicone copolymer resins, the difference in static friction coefficients of at least two vinyl acetate-silicone copolymer resins is preferably 0.03 or more, more preferably 0.04 or more, and even more preferably 0.05 or more. When the above difference in static friction coefficients is 0.03 or more, the static friction coefficient and dynamic friction coefficient of the top coat layer 11 can be easily adjusted to the range described later.

[0148] The topcoat layer 11 may further contain an acrylic resin. The acrylic resin functions as a binder in the topcoat layer 11. By using an acrylic resin in addition to the vinyl acetate-silicone copolymer resin, the static and dynamic friction coefficients of the topcoat layer 11 can be easily adjusted to the ranges described later.

[0149] The topcoat layer 11 may contain a binder resin other than the vinyl acetate-silicone copolymer resin and the acrylic resin. The content of the vinyl acetate-silicone copolymer resin and / or the acrylic resin in the topcoat layer 11 is preferably 60% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, and may be 95% by mass or more or 98% by mass or more, based on the total amount of binder (100% by mass).

[0150] The content of the vinyl acetate-silicone copolymer resin in the top coat layer 11 is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more, based on the total amount of the binder (100% by mass), and may also be 60% by mass or more, or 70% by mass or more. Furthermore, the above content may be 100% by mass, or 95% by mass or less, 80% by mass or less, 40% by mass or less, or 30% by mass or less.

[0151] If the topcoat layer 11 contains the above-mentioned acrylic resin, the content of the above-mentioned acrylic resin in the topcoat layer 11 is preferably 5% by mass or more, and may be 10% by mass or more, 10% by mass or more, 20% by mass or more, or 70% by mass or more, based on the total amount of the above-mentioned binder (100% by mass). Furthermore, the above content is preferably 90% by mass or less, more preferably 80% by mass or less, even more preferably 70% by mass or less, and may be 40% by mass or less or 30% by mass or less.

[0152] The top coat layer 11 may further contain crosslinking agents, fillers, waxes, surfactants, defoaming agents, etc. Each of these components may be used individually or in combination of two or more.

[0153] The topcoat layer 11 preferably contains a crosslinking agent from the viewpoint of obtaining a sufficiently cured topcoat layer. Zirconium carbonate is an example of the crosslinking agent. The amount of the crosslinking agent is preferably 0.3 to 8 parts by mass, more preferably 0.5 to 6 parts by mass, and even more preferably 2 to 5 parts by mass, based on the total amount of the binder (100 parts by mass).

[0154] Examples of the above-mentioned fillers include colloidal silica, calcium carbonate, zirconium carbonate, polymethyl methacrylate (PMMA), and polystyrene (PS). The particle size of these fillers is preferably 1.0 μm or less, and preferably 12 nm or more. Among the above-mentioned fillers, colloidal silica and calcium carbonate are preferred from the viewpoint of excellent sticking suppression, transparency, heat resistance, coating liquid stability, and peelability. The amount of the above-mentioned filler is preferably 20 to 50 parts by mass, and more preferably 22 to 45 parts by mass, relative to the total amount of the above-mentioned binder (100 parts by mass).

[0155] Examples of the above waxes include polyethylene and zinc stearate. Among these, polyethylene is preferred from the viewpoint of excellent stability and release properties of the coating liquid. The amount of the above lubricant is preferably 3 to 15 parts by mass, more preferably 5 to 13 parts by mass, and even more preferably 6 to 12 parts by mass, relative to the total amount of the above binder (100 parts by mass).

[0156] The coating amount (dry mass) of the topcoat layer 11 is, for example, preferably 0.3 to 10 g / m². 2 And more preferably 0.5~5.0 g / m 2The thickness of the topcoat layer 11 is preferably 0.3 to 20 μm, and more preferably 0.5 to 5.0 μm. When the amount and thickness of the topcoat layer 11 are within the above range, it is preferable from the viewpoint that the resulting thermal recording body 4 will have better color development and other properties.

[0157] The coefficient of dynamic friction of the surface of the topcoat layer 11 is 0.30 or less, and may be 0.27 or less, 0.25 or less, or 0.23 or less. When the coefficient of dynamic friction is 0.30 or less, the peelability of the surface of the topcoat layer 11 is excellent. Furthermore, from the viewpoint of having better printability of the surface of the topcoat layer 11, the coefficient of dynamic friction is preferably 0.11 or more, and may be 0.14 or more or 0.18 or more.

[0158] The static friction coefficient of the surface of the topcoat layer 11 is 0.19 or higher, and may be 0.20 or higher, 0.25 or higher, or 0.30 or higher. When the static friction coefficient is 0.19 or higher, the printability of the surface of the topcoat layer 11 is excellent. Furthermore, from the viewpoint of having better peelability of the surface of the topcoat layer 11, the static friction coefficient is preferably 0.52 or lower, and may be 0.50 or lower or 0.45 or lower.

[0159] The dynamic and static friction coefficients of the surface of the topcoat layer 11 are measured as follows: A thermal recording body is attached to a horizontal board using a commercially available adhesive sheet so that the topcoat layer is on top. Then, a polystyrene board is laminated onto the coating layer, and a weight is placed on top of the polystyrene board so that the total weight of the polystyrene board and weight is 418g. The laminate of polystyrene board and weight is moved on the coating layer at 10mm / min, and the static and dynamic friction coefficients of the surface of the coating layer are measured at this time.

[0160] The top coat layer 11 is placed on adhesive paper with an acrylic adhesive that conforms to JIS Z0237 (2009) and has an adhesive strength of 0.40 ± 0.15 N / 10 mm (standard value), and the adhesive is applied at 10 kg / cm². 2The peel strength when a T-shaped peel is performed under conditions of 23°C and a peeling speed of 300 mm / min after being pressed for 10 minutes under a load is preferably 1100 mN / 50 mm or less, more preferably 1000 mN / 50 mm or less, and even more preferably 800 mN / 50 mm or less. When the above peel strength is 1100 mN / 50 mm or less, the peelability of the topcoat layer 11 surface is excellent. The above peel strength can be specifically measured by the method described in the examples.

[0161] (Adhesive layer) The material used to form the adhesive layer 5 is not particularly limited, and any known or conventional adhesive can be used. Furthermore, the adhesive layer 5 may contain other components.

[0162] Examples of the above-mentioned adhesives include acrylic adhesives, rubber adhesives (natural rubber-based, synthetic rubber-based, mixtures thereof, etc.), silicone adhesives, polyester adhesives, urethane adhesives, polyether adhesives, polyamide adhesives, and fluorine adhesives. One type of adhesive may be used, or two or more types may be used. Furthermore, the composition forming the above-mentioned adhesive is not particularly limited and may be an emulsion type, a solvent type, or a solvent-free type.

[0163] The coating amount (dry mass) of the adhesive layer 5 is, for example, 0.3 to 50 g / m². 2 Preferably, and more preferably, 5 to 40 g / m² 2 Therefore, when the amount of coating is within the above range, the adhesive strength will be within a more suitable range.

[0164] (Backcourt layer) The back coat layer 6 is provided on the surface between the substrate 7 and the adhesive layer 5. When the adhesive layer 5 is provided on the substrate 7, the adhesive layer 5 can be laminated on one surface of the substrate 7 via the back coat layer 6. By providing the back coat layer 6, curling of the thermal recording body 4 can be suppressed. The back coat layer 6 can be formed mainly of resin. The resin is not particularly limited, but examples include those similar to those exemplified in the sections on the undercoat layer 8 and the intermediate layer 10. The back coat layer 6 may also contain other components as needed. Examples of these other components include crosslinking agents, surfactants, and preservatives. Examples of crosslinking agents include those similar to those exemplified in the section on the intermediate layer 10. Note that the back coat layer 6 is not necessarily required.

[0165] [Method for manufacturing thermal recording media] The thermal recording material of the present invention can be manufactured by known or conventional methods. For example, a method for manufacturing the thermal recording material 4 shown in Figure 2 will be described. First, paints for forming each layer are prepared by conventional methods.

[0166] (Preparation process) The method for preparing the above coating solution is not particularly limited, and for example, it can be prepared by pre-dispersing all the materials used in each layer in the same solvent. Alternatively, in preparing the coating solution for the thermal recording layer, the dye and developer, which react with each other, may be prepared as separate dispersions and then mixed together to form the coating solution for the thermal recording layer. 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. Examples of methods for preparing the above coating solution for the thermal recording layer include stirring, ultrasonic treatment, crushing treatment using a ball mill, bead mill, sand mill, high-pressure homogenizer, etc. One of these methods may be used, or two or more may be used.

[0167] (Coating process) The method of applying the above coating liquid is not particularly limited and includes methods such as direct application to the substrate or application to release paper and then transfer to the substrate. Examples of coating methods include air knife coating, barrier blade coating, pure blade coating, rod blade coating, short dwell coating, curtain coating, die coating, and gravure coating. Hand application using a wire bar is also acceptable. One of these methods may be used, or two or more may be used.

[0168] (drying process) The method for drying the above coating liquid is not particularly limited and includes, for example, heat drying, room temperature drying, and vacuum drying. One of these methods may be used, or two or more may be used. Furthermore, when each layer is formed by transferring it to the substrate 7, drying may be performed after transferring to the substrate 7, or after drying.

[0169] As described above, an undercoat layer 8, a thermal recording layer 9, an intermediate layer 10, and a topcoat layer 11 are sequentially formed on one side of the substrate 7. Then, a backcoat layer 6 and an adhesive layer 5 are sequentially formed on the other side of the substrate 7. In this way, a thermal recording body 4 can be manufactured.

[0170] The thermal recording material of the present invention is peelable from the topcoat layer and printable on the topcoat layer. Therefore, for example, by overlaying an adhesive surface on the topcoat layer, the surface can be protected until use, and can be easily peeled off from the topcoat layer when in use. Furthermore, printing can be applied to the topcoat layer. [Examples]

[0171] 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. Examples 10 and 11 are provided for reference only.

[0172] Example 1 (Preparation of thermal recording media) <Undercoat layer> An undercoat coating solution containing 70% by mass of hollow particles, 20% of styrene-butadiene latex (SBR) as a binder, 10% by mass of zinc stearate as a lubricant, and water as a solvent was prepared by conventional means. The obtained undercoat coating solution was applied to one surface of a substrate of fine paper by conventional means and dried, resulting in a coating amount of 1.0 g / m². 2 An undercoat layer of (dry mass) was formed.

[0173] <Thermal recording layer> A thermal recording layer coating solution (solid content 27% by mass) was prepared by conventional methods, containing 10.9% by mass of 3-dibutylamino-6-methyl-7-anilinofluorane as a dye, 22.4% by mass of 1,2-bis(3-methylphenoxy)ethane as a sensitizer, 27.1% by mass of N,N'-di-[3-(p-toluenesulfonyloxy)phenyl]urea as a color developer, 10.0% by mass of calcium carbonate as a filler, 18.6% by mass of styrene-butadiene latex (SBR) as a binder, 3.3% by mass of zinc stearate as a lubricant, 7.7% by mass of acrylic resin as a dispersant, and water as a solvent. The above thermal recording layer coating solution was applied to the surface of the undercoat layer by conventional methods and dried to form a thermal recording layer with a coating amount of 4.0 g / m2 (dry mass). The values ​​for each material listed above represent the mass ratio of each material to 100% by mass of the thermal recording layer (in a dry state).

[0174] <Middle class> Using water as the solvent, a core-shell type acrylic emulsion with a solid content concentration of 20% by mass is coated onto the surface of the thermal recording layer by a conventional method and dried, resulting in a coating amount of 1.6 g / m². 2 An intermediate layer of (dry mass) was formed.

[0175] <Top coat layer> A topcoat coating solution (solid content 20% by mass) was prepared by conventional means, containing vinyl acetate-silicone copolymer resin emulsion B and an acrylic resin as binders, zirconium ammonium carbonate as a crosslinking agent, polystyrene wax as a lubricant, fillers A and B as fillers, and water as a solvent. The topcoat coating solution was then applied to the surface of the intermediate layer by conventional means and dried, resulting in a coating amount of 1.1 g / m². 2 A topcoat layer of (dry mass) was formed.

[0176] <Backcoat layer> Using water as a solvent, a styrene acrylic resin with a solid content concentration of 20% by mass is coated onto the other surface of the above substrate by a conventional method and dried, resulting in a coating amount of 2.0 g / m². 2 A backcoat layer of (dry mass) was formed.

[0177] <Adhesive layer> By applying the acrylic adhesive to the surface of the back coat layer using a conventional method and drying it, the coating amount is 15 g / m². 2 An adhesive layer of (dry mass) was formed. In this way, a thermal recording body of Example 1 having a laminated structure of [adhesive layer / back coat layer / substrate / undercoat layer / thermal recording layer / intermediate layer / top coat layer] was produced.

[0178] Examples 2-9 and Comparative Examples 1-3 A thermal recording body was prepared in the same manner as in Example 1, except that the composition of the coating liquid for the top coat layer was changed as shown in Table 1.

[0179] Table 1 shows the proportions of various raw materials used in the topcoat coating liquid for each example. The values ​​for each material in Table 1 represent the mass of the dry material excluding water, and the unit is "mass%".

[0180] [Table 1]

[0181] <Rating> The thermal recording materials prepared in the examples and comparative examples were evaluated as follows. The results are shown in Table 2.

[0182] (1) coefficient of friction The adhesive layer was attached to a horizontal plate so that the topcoat layer of the thermal recording material was facing upwards. Then, a polystyrene plate was laminated onto the coating layer, and a weight was placed on top of the polystyrene plate so that the total weight of the polystyrene plate and weight was 418g. The laminate of polystyrene plate and weight was moved on the coating layer at 10 mm / min, and the static and dynamic friction coefficients of the surface of the coating layer were measured at this time. A polystyrene plate was used as the weight in contact with the topcoat layer. A Tensilon universal tester (product name "RTC-1210A", manufactured by Orientec Co., Ltd.) was used to measure the friction coefficients.

[0183] (2) Peel strength Adhesive paper with an acrylic adhesive having an adhesive strength of 0.40±0.15 N / 10 mm (standard value) in accordance with JIS Z0237 (2009) is layered on top of the top coat layer of the thermal recording material, at a density of 10 kg / cm². 2 The material was pressed under a load for 10 minutes and then cut to a size of 50 mm wide x 100 mm long. The peel strength was then measured when the thermal recording material was peeled in a T-shape from the adhesive paper under conditions of 23°C and a peeling speed of 300 mm / min. A Tensilon universal tester (product name "RTC-1210A", manufactured by Orientec Co., Ltd.) was used to measure the peel strength.

[0184] (3) Ink suitability UV ink was applied to the surface of the topcoat layer of a thermal recording medium using an RI tester and cured with a UV lamp. The ink's suitability was then evaluated based on the following evaluation criteria. <Evaluation Criteria> ◎ (Excellent): The ink adhered without any problems. ○ (Good): The ink was slightly faint but still legible. × (Defective): Almost no ink adhered.

[0185] [Table 2]

[0186] As shown in Table 2, the thermal recording materials of the examples had low peel strength, excellent peelability, and good ink compatibility. Therefore, the thermal recording materials of the examples were evaluated as being peelable from the topcoat layer and printable on the topcoat layer. On the other hand, when the coefficient of dynamic friction was high (Comparative Examples 1-3), the peel strength was high and peeling was difficult.

[0187] Example 10 (Preparation of release paper) A release layer coating solution (solid content concentration 20% by mass) containing vinyl acetate-silicone copolymer resin emulsion A as a binder and water as a solvent was prepared by conventional means. Then, the above release layer coating solution was applied to one surface of fine paper by conventional means and dried, resulting in a coating amount of 1.1 g / m². 2 A release layer of (dry mass) was formed to produce the release paper of Example 10.

[0188] Examples 11-16 and Comparative Examples 4-5 Release paper was prepared in the same manner as in Example 10, except that the composition of the release layer coating solution was changed as shown in Table 3.

[0189] Table 3 shows the proportions of various raw materials used in the release layer coating liquid for each example. The values ​​for each material in Table 3 represent the mass of the dry material excluding water, and the unit is "mass%".

[0190] [Table 3]

[0191] <Rating> The release papers prepared in the examples and comparative examples were evaluated as follows. The results are shown in Table 4.

[0192] (1) coefficient of friction The release paper was attached to a horizontal board using a commercially available adhesive sheet, with the release layer facing upwards. Then, a polystyrene board was laminated onto the coating layer, and a weight was placed on top of the polystyrene board so that the total weight of the polystyrene board and weight was 418g. The laminate of polystyrene board and weight was moved on the coating layer at 10mm / min, and the static and dynamic friction coefficients of the surface of the coating layer were measured at this time. A Tensilon universal tester (product name "RTC-1210A", manufactured by Orientec Co., Ltd.) was used to measure the friction coefficients.

[0193] (2) Peel strength Adhesive paper with an acrylic adhesive having an adhesive strength of 0.40±0.15 N / 10 mm (standard value) in accordance with JIS Z0237 (2009) is layered on top of the release layer of the release paper, at a rate of 10 kg / cm². 2 The material was pressed under a load for 10 minutes and then cut to a size of 50 mm wide x 100 mm long. The peel strength was then measured when the release paper was peeled in a T-shape from the adhesive paper under conditions of 23°C and a peeling speed of 300 mm / min. A Tensilon universal tester (product name "RTC-1210A", manufactured by Orientec Co., Ltd.) was used to measure the peel strength.

[0194] (3) Ink suitability UV ink was applied to the surface of the release layer of the release paper using an RI tester and cured with a UV lamp. Then, the ink suitability was evaluated based on the following evaluation criteria. <Evaluation Criteria> ◎ (Excellent): The ink adhered without any problems. ○ (Good): The ink was slightly faint but still legible. × (Defective): Almost no ink adhered.

[0195] [Table 4]

[0196] As shown in Table 4, the release paper of the example had low peel strength, excellent peelability, and good ink compatibility. Therefore, the release paper of the example was evaluated as being able to be peeled from the adhesive layer and being printable on the release layer. On the other hand, when the dynamic friction coefficient was high (Comparative Example 4), the peel strength was high and it was evaluated as difficult to peel. Also, when the static friction coefficient was low (Comparative Example 5), the ink compatibility was poor and it was evaluated as difficult to print on the release layer.

[0197] The various raw materials shown in Tables 1 and 3 are as follows: <Vinyl acetate-silicone copolymer resin emulsion> Vinyl acetate / silicone graft copolymer resin emulsion A: Solid content concentration 29-31% by mass, static friction coefficient 0.24, dynamic friction coefficient 0.12 Vinyl acetate / silicone graft copolymer resin emulsion B: Solid content concentration 29-31% by mass, static friction coefficient 0.18, dynamic friction coefficient 0.10 Vinyl acetate / silicone graft copolymer resin emulsion C: Solid content concentration 29-31% by mass, static friction coefficient 0.45, dynamic friction coefficient 0.42 Vinyl acetate / silicone graft copolymer resin emulsion D: Solid content concentration 29-31% by mass, static friction coefficient 0.43, dynamic friction coefficient 0.21 <Acrylic resin> Acrylic resin: Core-type acrylic resin <Filler> Filler A: Colloidal silica Filler B: Calcium carbonate

[0198] The following describes variations of the invention relating to this disclosure. [Note 1] The paper substrate and the release layer provided on the paper substrate are provided. The aforementioned release layer contains a vinyl acetate-silicone copolymer resin. The coefficient of dynamic friction of the surface of the release layer is 0.30 or less. Release paper having a static friction coefficient of 0.19 or higher on the surface of the release layer. [Note 2] The release paper described in Note 1 has a dynamic friction coefficient of 0.11 to 0.30. [Note 3] The release paper described in Note 1 or 2, wherein the static friction coefficient is 0.19 to 0.52. [Note 4] The release layer is placed on adhesive paper with an acrylic adhesive having an adhesive strength of 0.40 ± 0.15 N / 10 mm (standard value) in accordance with JIS Z0237 (2009), and the adhesive strength is 10 kg / cm². 2 Release paper as described in any one of the appendices 1 to 3, wherein the peel strength when peeled in a T-shape under conditions of 23°C and a peeling speed of 300 mm / min after being pressed with a load for 10 minutes is 1100 mN / 50 mm or less. [Note 5] The release layer further comprises an acrylic resin, as described in any one of Notes 1 to 4. [Note 6] The release layer is a release paper according to any one of Notes 1 to 5, comprising two vinyl acetate-silicone copolymer resins having a difference in static friction coefficient of 0.03 or more. [Note 7] A thermal recording body comprising an adhesive layer, a thermal recording layer, and a top coat layer, The top coat layer contains a vinyl acetate-silicone copolymer resin. The coefficient of dynamic friction of the surface of the topcoat layer is 0.30 or less. A thermal recording body having a static friction coefficient of 0.19 or higher on the surface of the top coat layer. [Note 8] The thermal recording body described in Note 7, wherein the coefficient of dynamic friction is 0.11 to 0.30. [Note 9] The thermal recording body according to Note 7 or 8, wherein the static friction coefficient is 0.19 to 0.52. [Note 10] The top coat layer is superimposed on adhesive paper with an acrylic adhesive having an adhesive strength of 0.40 ± 0.15 N / 10 mm (standard value) in accordance with JIS Z0237 (2009), at a rate of 10 kg / cm². 2 A thermal recording body as described in any one of the appendices 7 to 9, wherein the peel strength when peeled in a T-shape under conditions of a temperature of 23°C and a peeling speed of 300 mm / min after being pressed with a load for 10 minutes is 1100 mN / 50 mm or less. [Note 11] The thermal recording body according to any one of Notes 7 to 10, wherein the top coat layer further comprises an acrylic resin. [Note 12] The thermal recording body according to any one of Notes 7 to 11, wherein the top coat layer contains two vinyl acetate-silicone copolymer resins having a difference of 0.03 or more in static friction coefficients. [Explanation of Symbols]

[0199] 1 Release paper 2 Paper base material 3 Release layer 4. Thermal recording medium 5. Adhesive layer 6. Backcourt Layer 7 Base material 8. Undercoat layer 9. Thermal recording layer 10 Middle Class 11. Top coat layer

Claims

1. It comprises a paper substrate and a release layer provided on the paper substrate, The aforementioned release layer contains a vinyl acetate-silicone copolymer resin. The coefficient of dynamic friction of the surface of the release layer is 0.30 or less. The static friction coefficient of the surface of the release layer is 0.19 or higher. The release layer is a release paper that satisfies at least one of the following conditions (i) and (ii). (i) The release layer further comprises an acrylic resin (ii) The release layer contains two types of vinyl acetate-silicone copolymer resins having a difference of 0.03 or more in static friction coefficients.

2. The release paper according to claim 1, wherein the coefficient of dynamic friction is 0.11 to 0.

30.

3. The release paper according to claim 1 or 2, wherein the static friction coefficient is 0.19 to 0.

52.

4. The aforementioned release layer is placed on adhesive paper with an acrylic adhesive having an adhesive strength of 0.40 ± 0.15 N / 10 mm (standard value) in accordance with JIS Z0237 (2009), and the adhesive strength is 10 kg / cm². ２ The release paper according to claim 1 or 2, wherein the release strength when peeled in a T-shape under the conditions of a temperature of 23°C and a peeling speed of 300 mm / min after being pressed with a load for 10 minutes is 1100 mN / 50 mm or less.

5. A thermal recording body comprising an adhesive layer, a thermal recording layer, and a top coat layer, The top coat layer contains a vinyl acetate-silicone copolymer resin. The coefficient of dynamic friction of the surface of the topcoat layer is 0.30 or less. The static friction coefficient of the surface of the top coat layer is 0.19 or higher. The top coat layer is a thermal recording material that satisfies at least one of the following conditions (i) and (ii). (i) The top coat layer further comprises an acrylic resin (ii) The top coat layer contains two types of vinyl acetate-silicone copolymer resins having a difference of 0.03 or more in static friction coefficients.

6. The thermal recording body according to claim 5, wherein the coefficient of dynamic friction is 0.11 to 0.

30.

7. The thermal recording body according to claim 5 or 6, wherein the static friction coefficient is 0.19 to 0.

52.

8. The aforementioned topcoat layer is superimposed onto adhesive paper with an acrylic adhesive having an adhesive strength of 0.40 ± 0.15 N / 10 mm (standard value) in accordance with JIS Z0237 (2009), at a rate of 10 kg / cm². ２ The thermal recording body according to claim 5 or 6, wherein the peel strength when peeled in a T-shape from a state in which a load has been applied and pressed for 10 minutes, under the conditions of a temperature of 23°C and a peeling speed of 300 mm / min, is 1100 mN / 50 mm or less.

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