JP2015058579A - Reversible thermosensitive recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reversible thermosensitive recording material which allows formation/erasure of an image having a sharp contrast, which can hold an image stable with time and allows stable and repetitive formation/erasure of an image in an environment of a daily life, which minimizes conveyance failure due to charging in an image forming apparatus, which gives excellent visibility of a formed image, and which is significantly improved in receptivity of a printing ink, prevention of peeling after the recording material is formed into a card, and the like.SOLUTION: The reversible thermosensitive recording material includes at least the following reversible thermosensitive recording layer disposed on a support body: the reversible thermosensitive recording layer comprises a dye precursor that is colorless or in a pale color, and a reversible color developer that forms a coloring state and an erased state depending on a difference in a heating temperature and/or a cooling rate after heating. An outermost surface layer of the recording material, on at least either of the surface on the same side as the reversible thermosensitive recording layer and the surface on the opposite side, contains at least one compound in salts between a dicyanamide anion and a quaternary ammonium cation, a pyridinium cation or an imidazolium cation.

Description

  The present invention relates to a reversible thermosensitive recording material whose transparency or color tone reversibly changes by controlling thermal energy.

  In recent years, a reversible thermosensitive recording material that can form a temporary image and erase the image when it is no longer needed attracts attention. As a reversible thermosensitive recording material, a thermosensitive recording material using a colorless or light-colored dye precursor and a reversible color developer that develops color by heating the dye precursor and then re-heats it to erase the color. (See, for example, Patent Documents 1 to 3), a heat-sensitive recording material in which organic low-molecular substances such as higher fatty acids are dispersed in a resin such as vinyl chloride-vinyl acetate, and a heat-sensitive recording material in which two or more polymers having different refractive indexes are mixed. Etc. are known. In particular, a reversible thermosensitive recording material composed of a dye precursor and a reversible developer can form and erase recorded images with high contrast and high sensitivity many times. Have been widely used for the purpose of visualizing information in the card.

  Furthermore, in recent years, process management cards, labels, signboards, general document recording, etc. have been expanded as uses beyond the scope of point cards, prepaid cards, etc., and the reversible thermosensitive recording material has become larger. . This is more likely to cause electrification due to sheet friction during conveyance in the image forming apparatus and other general handling, and the conveyance of the apparatus due to sticking between sheets is more likely to occur. On the other hand, printing by sucking in dust, dust, etc. It becomes easy to induce a defect.

  As a countermeasure, a method for obtaining an antistatic effect has been reported. A method in which a polymer cationic conductive agent is contained in a reversible thermosensitive recording layer or overcoat layer is shown (for example, see Patent Document 4). However, the polymer cationic conductive agent has low compatibility in the coating layer, and as a result, it has been difficult to obtain a sufficient antistatic effect. Also, a method of adding a conductive metal oxide semiconductor powder to any layer of the reversible thermosensitive recording material (see, for example, Patent Document 5), or acicular conductive that is titanium oxide coated with antimony-doped tin oxide. Providing a layer containing a conductive filler has been proposed (see, for example, Patent Document 6). However, in any case, the opacity of the layer is increased, and the visibility of the formed printed image is lowered, or the background color has an unintended color tone. Further, since antimony is an environmental impact substance, it is desired to develop a reversible thermosensitive recording medium using a material having a low environmental impact. Further, when the wireless IC is sealed between the base materials, the shielding effect of the wireless signal is generated by the metal oxide semiconductor powder or the conductive filler, and the reading accuracy may be lowered, which is not preferable.

  On the other hand, it has been proposed to include an ionic liquid having a specific structure in a reversible thermosensitive recording material (see, for example, Patent Documents 7 and 8). However, in order to obtain an antistatic effect, it is necessary to add a large amount of ionic liquid in the layer, and bleeding out over time has been a problem. For this reason, when it is contained in the overcoat layer or the backcoat layer, there is a problem that the printing ink fillability is lowered and the printability becomes insufficient, or the media stick to each other due to stickiness. Further, when it is contained in the adhesive layer, there is a problem that the reversible thermosensitive recording material is easily peeled off from the bonded substrate after card molding by hot press or the like. Moreover, since this ionic liquid contains halogen in its structure, there was a concern about environmental burden.

JP-A-6-210955 Japanese Patent Laid-Open No. 7-179043 JP 2000-263946 A JP-A-5-96853 Japanese Patent Laid-Open No. 11-91243 JP 2005-193564 A JP 2007-137000 A JP 2007-223114 A

  It is an object of the present invention to form and erase an image having a clear contrast, to maintain a stable image over time in an environment of daily life, and to stably form and erase images repeatedly. It is an object of the present invention to provide a reversible thermosensitive recording material that has few conveyance failures in a forming apparatus, is excellent in visibility of a formed image, and has markedly improved printing ink fillability and peeling after card molding.

  As a result of intensive studies to solve these problems, the present inventor has found that the above-described problems can be solved by the following invention.

(I) In a reversible thermosensitive recording material provided with a thermosensitive recording layer whose transparency or color tone is reversibly changed by controlling thermal energy on a support, the same or opposite surface of the reversible thermosensitive recording layer A dicyanamide anion represented by the following general formula (1), a quaternary ammonium cation represented by the following general formula (2), and a pyridinium represented by the following general formula (3) on the outermost layer of at least one surface of A reversible thermosensitive recording material comprising at least one salt of a cation or an imidazolium cation represented by the following general formula (4).

(In General Formula (2), at least one group of R ₁ to R ₄ represents an aliphatic hydrocarbon group having 6 to 22 carbon atoms, and the remaining group is a hydroxyalkyl group having 1 to 3 carbon atoms, An aliphatic hydrocarbon group having 1 to 5 carbon atoms, an aryl group having 6 to 11 carbon atoms, or an arylalkyl group having 7 to 12 carbon atoms, and when there are a plurality of the remaining groups, they are the same as each other It may or may not be.)

(In General Formula (3), R ₅ represents an aliphatic hydrocarbon group having 1 to 22 carbon atoms, and R ₆ represents a hydrogen atom or an aliphatic hydrocarbon group having 1 to 8 carbon atoms.)

(In the general formula (4), R ₇ and R ₈ may be the same or different and each represents an aliphatic hydrocarbon group having 1 to 12 carbon atoms, and R ₉ is a hydrogen atom or an aliphatic hydrocarbon having 1 to 8 carbon atoms. Represents a hydrocarbon group.)

(II) The reversible thermosensitive recording material according to (I), wherein the salt of the dicyanamide anion and the organic cation is a halogen-free organic salt that is liquid at room temperature.

  The reversible thermosensitive recording material of the present invention enables the formation and erasure of images with clear contrast, can hold images that are stable over time in the environment of daily life, and can be repeatedly formed and erased stably. Therefore, it is possible to provide a reversible thermosensitive recording material that has few conveyance failures in the image forming apparatus due to charging, is excellent in the visibility of the formed image, and has markedly improved printing ink fillability and peeling after card molding.

  The reversible thermosensitive recording material of the present invention will be described in detail below. The reversible thermosensitive recording material of the present invention is a reversible thermosensitive recording material in which a thermosensitive recording layer in which the transparency or color tone reversibly changes by controlling thermal energy is provided on one side of a support, on the same side as the thermosensitive recording layer. It is characterized in that at least one kind of halogen-free salt of dicyanamide anion and organic cation is contained in the outermost surface layer of at least one of the above surface and the opposite surface.

  In the present invention, the salt composed of a dicyanamide anion and an organic cation is a compound having a charge, and therefore has an excellent antistatic effect. Such a salt is preferably an ionic liquid having a property of being halogen-free, having a sufficiently low melting point and being liquid at room temperature. Such a salt exhibiting fluidity at room temperature does not localize in the added system, tends to move ions, and tends to exhibit a better antistatic effect even in an environment with low humidity. Moreover, since the above-mentioned salt is halogen-free, there is no corrosive property and the load on the environment is low.

  The dicyanamide anion in the present invention is represented by the following general formula (1).

  In the present invention, the counter cation combined with the dicyanamide anion is any one selected from the group consisting of a quaternary ammonium cation, a pyridinium cation, and an imidazolium cation.

  The quaternary ammonium cation in the present invention is represented by the following general formula (2).

In general formula (2), at least one group of R ₁ to R ₄ is an aliphatic hydrocarbon group having 6 to 22 carbon atoms, which may be linear or branched, It may be saturated or unsaturated. Examples of the aliphatic hydrocarbon group having 6 to 22 carbon atoms include n-hexyl group, 1-methylpentyl group, 1-ethylbutyl group, 2-methylpentyl group, 2-ethylbutyl group, heptyl group, 1-methylhexyl group. 1-ethylpentyl group, 2-methylhexyl group, 2-ethyl n-pentyl group, 3-methylhexyl group, 3-ethylpentyl group, n-octyl group, 1-methylheptyl group, 1-ethylhexyl group, 2 -Methylheptyl group, 2-ethylhexyl group, 3-methylheptyl group, 3-ethylhexyl group, 4-ethylhexyl group, n-nonyl group, 1-ethylheptyl group, 2-ethylheptyl group, 3-methyloctyl group, 3 -Ethylheptyl group, n-decyl group, 2-ethyloctyl group, n-undecyl group, n-dodecyl group, 2-ethyldecyl group, n-tridecyl group Group, 2-ethylundecyl group, n-tetradecyl group, 2-butyldecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, nn-octadecyl group, 9-cis-octadecenyl group, n -Nonadecyl group, n-icosyl group, n-henicosyl group, n-docosyl group, etc. are mentioned.

  Of these aliphatic hydrocarbon groups, from the viewpoint of lowering the melting point of the resulting salt, a linear or branched aliphatic hydrocarbon group having 8 to 14 carbon atoms, such as n- Octyl group, 2-ethylhexyl group, n-decyl group, 2-ethyloctyl group, n-dodecyl group, 2-ethyldecyl group, n-tetradecyl group, 2-butyldecyl group are more preferable, and linear chain having 12 to 14 carbon atoms. Particularly preferred are linear or branched aliphatic hydrocarbon groups.

  In general formula (2), the remaining group is a hydroxyalkyl group having 1 to 3 carbon atoms, an aliphatic hydrocarbon group having 1 to 5 carbon atoms, an aryl group having 6 to 11 carbon atoms, or 7 to 7 carbon atoms. And when there are a plurality of the remaining groups, they may be the same or different from each other. When the aryl group has 12 or more carbon atoms or the arylalkyl group has 13 or more carbon atoms, the resulting salt has a very high viscosity, which is not practical.

  In the general formula (2), examples of the hydroxyalkyl group having 1 to 3 carbon atoms include a hydroxymethyl group, a 2-hydroxyethyl group, a 2-hydroxypropyl group, and a 3-hydroxypropyl group.

  In general formula (2), the C1-C5 aliphatic hydrocarbon group may be linear or branched, and may be saturated or unsaturated. Examples of the aliphatic hydrocarbon group having 1 to 5 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, isobutyl group, tert-butyl group, and n-pentyl. Group, isopentyl group, tert-pentyl group, neopentyl group and the like. Of these aliphatic hydrocarbon groups, the melting point of the resulting salt is lower, so that a methyl group, an ethyl group, an n-propyl group, and an isopropyl group are preferable, and a methyl group is more preferable.

  In the general formula (2), as the aryl group having 6 to 11 carbon atoms, phenyl group, methylphenyl group, dimethylphenyl group, ethylphenyl group, trimethylphenyl group, methylethylphenyl group, n-propylphenyl group, isopropyl Examples include a phenyl group, a tetramethylphenyl group, a diethylphenyl group, and an isopropylmethylphenyl group. Among these aryl groups, a phenyl group, a methylphenyl group, a dimethylphenyl group, and an ethylphenyl group are preferable, and a phenyl group is more preferable because the melting point of the obtained salt is lower.

  In the general formula (2), examples of the arylalkyl group having 7 to 12 carbon atoms include a benzyl group, a phenylethyl group, a phenylpropyl group, and an isopropylbenzyl group. Among these arylalkyl groups, an arylalkyl group having 7 to 9 carbon atoms is preferable because the resulting salt has a lower melting point. As the arylalkyl group having 7 to 9 carbon atoms, a benzyl group and a phenylethyl group are more preferable, and a benzyl group is particularly preferable.

Among such quaternary ammonium cations, the melting point of the obtained salt is particularly low, and a more excellent antistatic effect can be obtained, so that R ₁ to R _{4 in the} general formula (2) are obtained. One of the groups is a linear or branched aliphatic hydrocarbon group having 8 to 14 carbon atoms, and two of the remaining groups are each independently a straight chain having 1 to 3 carbon atoms. A quaternary ammonium cation which is a chain or branched aliphatic hydrocarbon group and the remaining one group is an arylalkyl group having 7 to 9 carbon atoms is more preferable. In the general formula (2), One of R ₁ to R _{4 is} a linear or branched aliphatic hydrocarbon group having 12 to 14 carbon atoms, and two of the remaining groups are methyl groups; Furthermore, the remaining one group is a benzyl group quaternary ammonium cation Is particularly preferred.

  The pyridinium cation in the present invention is represented by the following general formula (3).

In general formula (3), R ₅ is an aliphatic hydrocarbon group having 1 to 22 carbon atoms, which may be linear or branched, and may be saturated or unsaturated. When the number of carbon atoms is 19 or more, the resulting salt has a very high viscosity. Therefore, an aliphatic hydrocarbon group having 1 to 18 carbon atoms is preferable. Examples of the alkyl group having 1 to 18 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, isobutyl group, tert-butyl group, n-pentyl group, and isopentyl group. Tert-pentyl group, neopentyl group, n-hexyl group, 1-methylpentyl group, 1-ethylbutyl group, 2-methylpentyl group, 2-ethylbutyl group, n-heptyl group, 1-methylhexyl group, 1-ethyl Pentyl group, 2-methylhexyl group, 2-ethylpentyl group, 3-methylhexyl group, 3-ethylpentyl group, n-octyl group, 1-methylheptyl group, 1-ethylhexyl group, 2-methylheptyl group, 2 -Ethylhexyl group, 3-methylheptyl group, 3-ethylhexyl group, 4-ethylhexyl group, n-nonyl group, 1-ethyl Ptyl group, 2-ethylheptyl group, 3-methyloctyl group, 3-ethylheptyl group, n-decyl group, 2-ethyloctyl group, n-undecyl group, n-dodecyl group, 3-ethyldecyl group, n-tridecyl Group, 2-ethylundecyl group, n-tetradecyl group, 2-butyldecyl group, n-pentadecyl group, 2-pentyldecyl group, n-hexadecyl group, 2-hexyldecyl group, n-heptadecyl group, 2-heptyldecyl group , N-octadecyl group, 2-octyldecyl group and the like.

Further, in the general formula (3), R ₆ is a hydrogen atom or an aliphatic hydrocarbon group having 1 to 8 carbon atoms. The aliphatic hydrocarbon group is preferably a saturated aliphatic hydrocarbon group having 1 to 4 carbon atoms because the resulting salt has a lower melting point. Examples of such an aliphatic hydrocarbon group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, and a tert-butyl group. An organic salt in which R ₆ is a hydrogen atom or a methyl group is particularly preferred because of excellent antistatic properties. In addition, it is more preferable that the position of the methyl group is the 3-position or the 4-position.

  The imidazolium cation in the present invention is represented by the following general formula (4).

In the general formula (4), R ₇ and R ₈ may be the same or different and each is an aliphatic hydrocarbon group having 1 to 12 carbon atoms, which may be linear or branched, saturated. Or unsaturated. When the number of carbon atoms of the aliphatic hydrocarbon group exceeds the upper limit, the viscosity of the resulting salt is increased, which is not practical. The aliphatic hydrocarbon group is preferably a saturated aliphatic hydrocarbon group having 1 to 8 carbon atoms from the viewpoint of lowering the melting point of the obtained salt. Examples of such aliphatic hydrocarbon groups include methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, and tert-pentyl. Group, neopentyl group, n-hexyl group, 1-methylpentyl group, 1-ethylbutyl group, 2-methylpentyl group, 2-ethylbutyl group, n-heptyl group, 1-methylhexyl group, 1-ethylpentyl group, 2 -Methylhexyl group, 2-ethylpentyl group, 3-methylhexyl group, 3-ethylpentyl group, n-octyl group, 1-methylheptyl group, 1-ethylhexyl group, 2-methylheptyl group, 2-ethylhexyl group, A 3-methylheptyl group, a 3-ethylhexyl group, a 4-ethylhexyl group, and the like can be given.

In the general formula (4), R ₉ is a hydrogen atom or an aliphatic hydrocarbon group having 1 to 8 carbon atoms, and when it is an aliphatic hydrocarbon group, it may be linear or branched. It may be saturated or unsaturated. The aliphatic hydrocarbon group is preferably a saturated aliphatic hydrocarbon group having 1 to 4 carbon atoms from the viewpoint of lowering the melting point of the resulting salt. Examples of such aliphatic hydrocarbon groups include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, an isobutyl group, and a tert-butyl group. An organic salt in which R ₉ is a hydrogen atom or a methyl group is particularly preferred because of excellent antistatic properties. It is more preferable that the position of the methyl group is the 2-position.

  As the reason why the organic salt composed of the dicyanamide anion and the organic cation in the present invention exhibits an excellent antistatic effect, the present inventors infer as follows. The dicyanamide anion has a molecular weight of about 66 and is one of the anions having the lowest molecular weight as an anion constituting an organic salt that usually has a melting point of room temperature or lower. Therefore, it is considered that the organic salt alone has a high conductivity and contributes to the reduction of the leakage resistance value in the layer to which the organic salt is added.

  Furthermore, among the organic cations represented by the general formulas (2) to (4), the antistatic effect of the pyridinium cation represented by the general formula (3) and the imidazolium cation represented by the general formula (4) is excellent. Therefore, a pyridinium cation represented by the general formula (3) is more preferable.

  In the present invention, a salt of a dicyanamide anion and an organic cation, more preferably a halogen-free salt, is formed on the outermost layer on at least one surface of the same side or the opposite side with respect to the reversible thermosensitive recording layer. Although it contains, it is more preferable to make it contain on both surfaces. When the reversible thermosensitive recording layer is the outermost layer, a halogen-free salt of dicyanamide anion and organic cation is added to the reversible thermosensitive recording layer. In the present invention, a protective layer can be provided on the reversible thermosensitive recording layer. When the protective layer is the outermost layer, a halogen-free salt of a dicyanamide anion and an organic cation is added to the protective layer. In view of durability during repeated use, the layer structure is preferable. The protective layer may be composed of a single layer or a plurality of layers of two layers or three layers or more, but the halogen-free salt of dicyanamide anion and organic cation is formed on the outermost layer of the laminated protective layer. Added. Further, for the purpose of adjusting the curl of the substrate, a backcoat layer can be provided on the surface opposite to the surface on which the reversible thermosensitive recording layer is provided. Further, a heat-sealing layer can be provided on the surface opposite to the surface on which the reversible thermosensitive recording layer is provided, and can be attached to another medium. When the backcoat layer or the heat-sealing layer is the outermost layer, a halogen-free salt of a dicyanamide anion and an organic cation is added to the backcoat layer or the heat-sealing layer.

  The protective layer and back coat layer in the present invention are preferably a curable resin because durability, heat resistance, water resistance, and adhesion during repeated use are required. Examples of the curable resin include a thermosetting resin, an electron beam curable resin, and an ultraviolet curable resin. When a thermosetting resin is applied, a liquid containing a crosslinking agent is applied and formed into a film, and then crosslinked by heat. Specific examples of thermosetting resins include epoxy resins, urea resins, xylene-formaldehyde resins, melamine resins, guanamine resins, phenol resins, phenoxy resins, saturated polyester resins, unsaturated polyester resins, and polyol resins. In addition, examples of the curing agent used in these thermosetting resins include organic acids, amines, isocyanates, epoxies, phenols, and the like. It only has to be selected. Among these, a crosslinked resin obtained by thermally curing a polyol compound with an isocyanate compound described in JP-A Nos. 10-230680 and 11-58963 is preferable.

  As oligomers / monomers used for electron beam curable resins or UV curable resins, there are many types of acrylic oligomers / monomers with excellent radiation curing properties, polyene-thiol oligomers / monomers, and photocationic polymerization type epoxy. Examples include oligomers and monomers. Examples of the acrylic monomer include a monofunctional monomer, a bifunctional monomer, and a polyfunctional monomer. In particular, a photopolymerization initiator and a photopolymerization accelerator are used at the time of ultraviolet crosslinking.

  Examples of the acrylic oligomer / monomer include polyester acrylate, polyether acrylate, epoxy acrylate, polyurethane acrylate, silicone acrylate, melamine acrylate, polybutadiene acrylate, and the like.

  In the present invention, the heat-sealing layer does not exhibit fusing property at room temperature, and exhibits fusing property at a heating temperature. Therefore, heating or heating is performed in a state where the heat-fusing surface is in contact with a substrate such as a card. Adhesion is possible by applying pressure. As a material constituting the heat-sealing layer in the present invention, it is possible to select and use a generally known heat-sealing agent such as a heat sealing agent, a hot press agent, a wet lamination, a dry lamination. Specific examples include vinyl acetate resins, polyester resins, polyurethane resins, vinyl chloride resins, vinyl chloride-vinyl acetate copolymer resins, polyamide resins, ethylene-vinyl acetate resins, olefin resins, and the like. One or two or more heat fusion agents can be used in combination.

  In the present invention, a reversible thermosensitive recording layer, a protective layer, an undercoat layer, a backcoat layer, and a heat fusion layer provided on a support, if necessary, a leveling agent, a dispersant, a hardener, Surfactant, thickener, hardener, preservative, filler, colored dye / pigment, fluorescent brightener, ultraviolet absorber, infrared absorber, antioxidant, anti-aging agent, pH adjuster, antifoaming agent, Various additives such as pigments, lubricants and antistatic agents can be added.

  In the present invention, the halogen-free salt of the dicyanamide anion and the organic cation may be used alone or in combination of two or more, and the addition amount may be added to the reversible thermosensitive recording layer, protective layer, 0.1 to 15% by mass, based on the total solid content including the binder resin, curable resin, thermal fusion resin, and various additives constituting the undercoat layer, backcoat layer, and thermal fusion layer Is preferable, and 1-10 mass% is more preferable.

  The reversible thermosensitive recording layer according to the present invention uses a material whose transparency or color tone reversibly changes by controlling thermal energy. For example, as a reversible thermosensitive recording material capable of repeating image recording and erasing, a reversible developer that imparts a reversible color change by heating to the dye precursor is used to control image formation by controlling thermal energy. A reversible thermosensitive recording material that can be erased, a low-molecular-weight organic material dispersed in a resin matrix, a cloudy reversible thermosensitive recording material that gives a transparent state and a cloudy state by heat, and two polymers with different refractive indexes. The reversible thermosensitive recording material etc. which were mixed above are mentioned. Further, these reversible thermosensitive recording layers may be formed by stacking a plurality of reversible thermosensitive recording layers having different colors. Among these, a reversible thermosensitive recording layer containing a dye precursor and a reversible developer is preferable because of excellent image visibility. There is no restriction | limiting in particular as a dye precursor concerning this invention, According to the objective, it can select suitably, For example, a leuco dye etc. are mentioned suitably. As the leuco dye, a fluorane compound or an azaphthalide compound can be preferably used. Hereinafter, although the specific example of a dye precursor is given, this invention is not limited to this.

  2-anilino-3-methyl-6-diethylaminofluorane, 2-anilino-3-methyl-6- (di-n-butylamino) fluorane, 2-anilino-3-methyl-6- (di-n-amylamino) ) Fluorane, 2-anilino-3-methyl-6- (di-iso-amylamino) fluorane, 2-anilino-3-methyl-6- (Nn-propyl-N-methylamino) fluorane, 2-anilino- 3-methyl-6- (N-isopropyl-N-methylamino) fluorane, 2-anilino-3-methyl-6- (N-isobutyl-N-methylamino) fluorane, 2-anilino-3-methyl-6 (Nn-amyl-N-methylamino) fluorane, 2-anilino-3-methyl-6- (N-sec-butyl-N-methylamino) fluorane, 2-anili -3-methyl-6- (Nn-amyl-N-ethylamino) fluorane, 2-anilino-3-methyl-6- (N-iso-amyl-N-ethylamino) fluorane, 2-anilino-3 -Methyl-6- (Nn-propyl-N-isopropylamino) fluorane, 2-anilino-3-methyl-6- (N-cyclohexyl-N-methylamino) fluorane, 2-anilino-3-methyl-6 -(N-ethyl-p-toluidino) fluorane, 2-anilino-3-methyl-6- (N-methyl-p-toluidino) fluorane.

  2- (m-trichloromethylanilino) -3-methyl-6-diethylaminofluorane, 2- (m-trifluoromethylanilino) -3-methyl-6-diethylaminofluorane, 2- (m-trichloromethyl) Anilino) -3-methyl-6- (N-cyclohexyl-N-methylamino) fluorane, 2- (2,4-dimethylanilino) -3-methyl-6-diethylaminofluorane, 2- (2,4 -Dimethylanilino) -3-methyl-6- (di-n-butylamino) fluorane, 2- (m-toluidino) -3-methyl-6-diethylaminofluorane, 2- (m-toluidino) -3- Methyl-6- (di-n-butylamino) fluorane, 2- (p-toluidino) -3-methyl-6-diethylaminofluorane, 2- (p-toluidino) -3- Tyl-6- (di-n-butylamino) fluorane, 2- (N-ethyl-p-toluidino) -3-methyl-6- (N-ethylanilino) fluorane, 2- (N-ethyl-p-toluidino) -3-methyl-6- (N-propyl-p-toluidino) fluorane, 2-anilino-6- (Nn-hexyl-N-ethylamino) fluorane, 2- (o-chloroanilino) -6-diethylaminofluor Oran, 2- (o-chloroanilino) -6-dibutylaminofluorane, 2- (m-trifluoromethylanilino) -6-diethylaminofluorane, 2,3-dimethyl-6-dimethylaminofluorane, 3- Methyl-6- (N-ethyl-p-toluidino) fluorane, 2-chloro-6-diethylaminofluorane.

  2-bromo-6-diethylaminofluorane, 2-chloro-6-dipropylaminofluorane, 3-chloro-6-cyclohexylaminofluorane, 3-bromo-6-cyclohexylaminofluorane, 2-chloro-6- (N-ethyl-N-isoamylamino) fluorane, 2-chloro-3-methyl-6-diethylaminofluorane, 2-anilino-3-chloro-6-diethylaminofluorane, 2- (o-chloroanilino) -3- Chloro-6-cyclohexylaminofluorane, 2- (m-trifluoromethylanilino) -3-chloro-6-diethylaminofluorane, 2- (2,3-dichloroanilino) -3-chloro-6-diethylamino Fluorane, 1,2-benzo-6-diethylaminofluorane, 3-diethylamino-6- (m-to Fluorochemicals methyl anilino) fluoran.

  3- (1-Ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-Ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3- (1-octyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4- Azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-methyl-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3- Yl) -3- (2-methyl-4-diethylaminophenyl) -7-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (4-diethyl) Aminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (4-Nn-amyl-N-methylaminophenyl) -4-azaphthalide, 3- ( 1-methyl-2-methylindol-3-yl) -3- (2-hexyloxy-4-diethylaminophenyl) -4-azaphthalide, 3,3-bis (2-ethoxy-4-diethylaminophenyl) -4- Azaphthalide, 3,3-bis (2-ethoxy-4-diethylaminophenyl) -7-azaphthalide.

  2- (p-acetylanilino) -6- (Nn-amyl-Nn-butylamino) fluorane, 2-benzylamino-6- (N-ethyl-p-toluidino) fluorane, 2-benzylamino -6- (N-methyl-2,4-dimethylanilino) fluorane, 2-benzylamino-6- (N-ethyl-2,4-dimethylanilino) fluorane, 2-benzylamino-6- (N- Methyl-p-toluidino) fluorane, 2- (di-p-methylbenzylamino) -6- (N-ethyl-p-toluidino) fluorane, 2- (α-phenylethylamino) -6- (N-ethyl- p-Toluidino) fluoran.

  2-methylamino-6- (N-methylanilino) fluorane, 2-methylamino-6- (N-ethylanilino) fluorane, 2-methylamino-6- (N-propylanilino) fluorane, 2-ethylamino-6 -(N-methyl-p-toluidino) fluorane, 2-methylamino-6- (N-methyl-2,4-dimethylanilino) fluorane, 2-ethylamino-6- (N-ethyl-2,4- Dimethylanilino) fluorane, 2-dimethylamino-6- (N-methylanilino) fluorane, 2-dimethylamino-6- (N-ethylanilino) fluorane, 2-diethylamino-6- (N-methyl-p-toluidino) fluorane 2-diethylamino-6- (N-ethyl-p-toluidino) fluorane, 2-dipropylamino-6- (N-methyl) Anilino) fluoran, 2-dipropylamino-6-(N-ethylanilino) fluoran.

  2-amino-6- (N-methylanilino) fluorane, 2-amino-6- (N-ethylanilino) fluorane, 2-amino-6- (N-propylanilino) fluorane, 2-amino-6- (N- Methyl-p-toluidino) fluorane, 2-amino-6- (N-ethyl-p-toluidino) fluorane, 2-amino-6- (N-propyl-p-toluidino) fluorane, 2-amino-6- (N -Methyl-p-ethylanilino) fluorane, 2-amino-6- (N-ethyl-p-ethylanilino) fluorane, 2-amino-6- (N-propyl-p-ethylanilino) fluorane, 2-amino-6- ( N-methyl-2,4-dimethylanilino) fluorane, 2-amino-6- (N-ethyl-2,4-dimethylanilino) fluorane, 2-amino-6 (N-propyl-2,4-dimethylanilino) fluorane, 2-amino-6- (N-methyl-p-chloroanilino) fluorane, 2-amino-6- (N-ethyl-p-chloroanilino) fluorane, 2 -Amino-6- (N-propyl-p-chloroanilino) fluorane, 1,2-benzo-6- (N-ethyl-N-isoamylamino) fluorane, 1,2-benzo-6-dibutylaminofluorane, , 2-Benzo-6- (N-methyl-N-cyclohexylamino) fluorane, 1,2-benzo-6- (N-ethyl-N-toluidino) fluorane.

  4,4'-bis (dimethylaminophenyl) benzhydrylbenzyl ether, N-chlorophenyl leucooramine, N-2,4,5-trichlorophenyl leucooramine, benzoyl leucomethylene blue, p-nitrobenzoyl leucomethylene blue, 3 -Methylspirodinaphthopyrans, 3-ethylspirodinaphthopyrans, 3,3'-dichlorospirodinaphthopyrans, 3-benzylspirodinaphthopyrans, 3-methylnaphthyl (3-methoxybenzo) spiropyrans, 3-propylspiros Benzopyran.

  These dye precursors may be used singly or in combination of two or more, and toning can also be performed by mixing dye precursors that develop colors in other colors. In addition, a multicolor reversible thermosensitive recording material or a full-color reversible thermosensitive recording material can be obtained by laminating layers that develop colors of different colors or arranging them on a plane. The dye precursor may be subjected to processing such as microencapsulation, resin coating, and composite particle formation with a resin.

  In the reversible thermosensitive recording layer constituted by using the dye precursor and the reversible developer according to the present invention, the reversible developer is not only the image formation by heating but also the development considering the erasure of the recorded image. The reversible thermosensitive recording layer using the reversible developer can rewrite the display contents repeatedly. Of course, it can also be used for applications in which image formation is performed only once, as in a normal heat-sensitive recording material. As the reversible developer, a compound represented by the following general formula (5) is preferably used. Note that the present invention is not limited to this. The reversible developers according to the present invention may be used alone or in combination of two or more.

In the general formula (5), X ₁ and X ₂ may be the same or different from each other, oxygen atoms, sulfur atoms, or —CO—, —NH—, which do not contain a hydrocarbon group at both ends, or It represents a divalent group having a —SO ₂ — bond as the minimum structural unit. R ₁₀ represents a single bond or a divalent hydrocarbon group having 1 to 20 carbon atoms. R ₁₁ represents a divalent hydrocarbon group having 1 to 20 carbon atoms. R ₁₂ represents a monovalent hydrocarbon group having 1 to 50 carbon atoms, preferably a hydrocarbon group having 6 to 36 carbon atoms. R ₁₀ and R ₁₁ mainly represent an alkylene group or an alkenylene group, and may contain an aromatic ring. R ₁₂ mainly represents an alkyl group or an alkenyl group. n represents an integer of 0 to 4, and R ₁₁ and X ₂ repeated when n is 2 or more may be the same or different.

X ₁ and X ₂ in the general formula (5) include a divalent group having a minimum constituent unit of —CO—, —NH—, or —SO ₂ — bond that does not contain a hydrocarbon group at both ends. Specific examples thereof include amide (—CONH—, —NHCO—), urea (—NHCONH—), diacylamine (—CONHCO—), diacylhydrazine (—CONHNHCO—), oxalic acid diamide (—NHCONCONH—), Acylurea (-CONHCONH-, -NHCONHCO-), Semicarbazide (-NHCONHNH-, -NHNHCONH-), Acyl semicarbazide (-CONHNHCONH-, -NHCONHNHCO-), 3-Acylcarbazate (-CONHNHCOO-, -OCONHNHCO-) ), sulfonamide (-NHSO ₂ -, - SO NH-), sulfonyl hydrazide _{(-SO 2 NHNHCO -, - CONHNHSO} 2 -) although groups such like, it is preferably an amide, urea, diacyl hydrazine, oxalic acid diamide, acyl semicarbazide.

  Specific examples of the reversible developer represented by the general formula (5) are given below, but the present invention is not limited thereto.

  Np-hydroxyphenyl-N'-octadecylurea, Np-hydroxyphenyl-N'-henicosylurea, Np-hydroxyphenyl-N'-docosylurea, Np-hydroxyphenyl-N'-pentacosyl Urea, Np-hydroxyphenyl-N'-hexacosyl urea, Np-hydroxyphenyl-N'-nonacosyl urea, Np-hydroxyphenyl-N'-triacontyl urea, Np-hydroxyphenyl-N ' -4-oxaoctadecylurea, Np-hydroxyphenyl-N'-12-thiatriacontylurea, N- [2- (p-hydroxyphenyl) ethyl] -N'-octadecylurea, N- [2- (P-hydroxyphenyl) ethyl] -N'-octadecylurea, N- [2- (p-hydroxyphenyl) ethyl ] -N'-henicosyl urea, N- [2- (p-hydroxyphenyl) ethyl] -N'-docosyl urea, N- [2- (p-hydroxyphenyl) ethyl] -N'-heptacosyl urea, N- [2- (p-hydroxyphenyl) ethyl] -N'-hexacosyl urea, N- [2- (p-hydroxyphenyl) ethyl] -N'-triacontyl urea, N- [2- (p-hydroxyphenyl) ethyl ] -N'-4-oxaoctadecyl urea, N- [2- (p-hydroxyphenyl) ethyl] -N'-12-thiatriacontyl urea.

  N- (p-hydroxyphenyl) docosanamide, N- (p-hydroxyphenyl) heptacosanamide, N- (p-hydroxyphenyl) hexacosanamide, N- (p-hydroxyphenyl) nonacosanamide, N- (p -Hydroxyphenyl) triacontanamid, N- (p-hydroxyphenyl) -12-thiatriacontanamid, N- [2- (p-hydroxyphenyl) ethyl] docosanamide, N- [2- (p-hydroxyphenyl) Ethyl] heptacosanamide, N- [2- (p-hydroxyphenyl) ethyl] hexacosanamide, N- [2- (p-hydroxyphenyl) ethyl] nonacosanamide, N- [2- (p-hydroxyphenyl) ) Ethyl] triacontanamid, N- [2- (p-hydroxyphenyl) ethyl ]-12-thia Tria near-end amide.

  N-docosyl-p-hydroxybenzamide, N-heptacosyl-p-hydroxybenzamide, N-hexacosyl-p-hydroxybenzamide, N-nonacosyl-p-hydroxybenzamide, N-triacontyl-p-hydroxybenzamide, N-4-oxa Octadecyl-p-hydroxybenzamide, N-docosyl- (p-hydroxyphenyl) acetamide, N-heptacosyl- (p-hydroxyphenyl) acetamide, N-hexacosyl- (p-hydroxyphenyl) acetamide, N-nonacosyl- (p -Hydroxyphenyl) acetamide, N-triacontyl- (p-hydroxyphenyl) acetamide, N-4-oxaoctadecyl- (p-hydroxyphenyl) acetamide, N-docosyl- [3- (p-hydride) Xylphenyl)] propionamide, N-heptasacosyl- [3- (p-hydroxyphenyl)] propionamide, N-hexacosyl- [3- (p-hydroxyphenyl)] propionamide, N-nonacosyl- [3- (p- Hydroxyphenyl)] propionamide, N-triacontyl- [3- (p-hydroxyphenyl)] propionamide, N-4-oxaoctadecyl- [3- (p-hydroxyphenyl)] propionamide.

  N- (p-hydroxybenzoyl) -N'-octadecanohydrazide, N- (p-hydroxybenzoyl) -N'-docosanohydrazide, N- (p-hydroxybenzoyl) -N'-hexacosanohydrazide, N- (p-hydroxybenzoyl) -N'-triacontanohydrazide, N- [3- (p-hydroxyphenyl) propiono] -N'-octadecanohydrazide, N- [3- (p-hydroxyphenyl) Propiono] -N'-docosanohydrazide, N- [3- (p-hydroxyphenyl) propiono] -N'-hexacosanohydrazide, N- [3- (p-hydroxyphenyl) propiono] -N'-tria Contanohydrazide, N- [3- (p-hydroxyphenyl) propiono] -N′-12-thiatriacontanohydrazide.

  Furthermore, specific examples of the reversible developer according to the present invention include the following structural formulas (6-1) to (8-9), but the present invention is not limited thereto. Absent.

  The reversible color developer according to the present invention may be used alone or in combination of two or more. The usage-amount with respect to a dye precursor is 5-5000 mass%, Preferably it is 10-3000 mass%.

  In the reversible thermosensitive recording material of the present invention, the reversible thermosensitive recording layer comprises a compound having at least one group selected from amide, urethane, urea, diacylhydrazine and oxalic acid diamide in the molecule as a decoloring accelerator. By using a quaternary ammonium salt compound in combination, an intermolecular interaction acts between the decoloring accelerator and the developer in the process of forming the erased state, and the erasing speed can be increased.

  As the decoloring accelerator, compounds represented by the following general formulas (6) to (13) are particularly preferable.

R ₁₃ -CONH ₂ ··· the general formula (6)
R ₁₃ -NHCONH ₂ ··· the general formula (7)
R < ₁₃ > -CONH-R < ₁₄ > ... General formula (8)
R < ₁₃ > -NHCONH-R < ₁₄ > ... General formula (9)
R < ₁₃ > -NHCOCONH-R < ₁₄ > ... General formula (10)
_{R 13 -CONHNHCO-R 14} ··· formula (11)
A-NHCONH-R ₁₄ ... General formula (12)
^{_{(R 13) 3 -N + -R}} 14 Z - ··· formula (13)

However, in General Formulas (6) to (13), R ₁₃ and R ₁₄ are synonymous, and are saturated or unsaturated hydrocarbon groups having 1 to 24 carbon atoms which may be the same or different from each other. Represents an optionally branched alkyl group, alkenyl group, aralkyl group, and aryl group, and these groups may be substituted with an alkyl group, alkenyl group, hydroxy group, halogen atom, alkoxy group, or the like. . Examples of R ₁₃ and R ₁₄ include methyl group, ethyl group, propyl group, butyl group, hexyl group, octyl group, dodecyl group, octadecyl group, behenyl group, allyl group, phenyl group, tolyl group, benzyl group and phenyl group. An ethyl group etc. are mentioned. A is a disubstituted acyclic amino group having a nitrogen atom directly bonded to the urea bond, or a nitrogen atom-containing 5- and 6-membered heterocyclic ring. In the case of a heterocyclic ring, the nitrogen atom in the ring is directly bonded to the urea bond. Are connected. When A is a heterocyclic ring, specific examples of the 5-membered ring include pyrrolidine ring, imidazolidine ring, thiazolidine ring, pyrrole ring, imidazole ring and pyrazole ring. Specific examples of the 6-membered ring include piperidine ring, Examples include a morpholine ring, a thiomorpholine ring, and a piperazine ring. Furthermore, the acyclic amino group and heterocyclic ring may be substituted with an alkyl group, an aralkyl group, an aryl group, a hydroxy group, or the like. Z represents an anion, and is halogen, substituted sulfonate, substituted phosphate, substituted borate, or substituted imide, preferably halogen or substituted sulfonate.

  The decoloring accelerators represented by the general formulas (6) to (13) may be used alone or in combination of two or more. The usage-amount with respect to a reversible developer is 0.1-100 mass%, Preferably it is 0.5-50 mass%, Most preferably, it is 1-20 mass%. If the amount used is less than 0.1% by mass, the decoloring promotion effect may not be exhibited. If the amount used exceeds 100% by mass, the color density may decrease and the heat stability of the printed image may decrease. .

  The support according to the present invention includes paper, non-woven fabric / woven fabric / knitted fabric, plastic film, resin-coated paper, synthetic paper, metal plate, metal foil, glass, quartz glass, silicon resin, aluminum oxide, silicon oxide Etc., or a combination of these can be arbitrarily used depending on the purpose. Examples of the plastic film that can be used in the present invention include polyester film, polyolefin film, polyvinyl alcohol film, polyvinyl chloride film, nylon film, polystyrene film, polyvinylidene chloride film, ethylene-vinyl acetate copolymer film, ethylene-vinyl. Examples include alcohol copolymer films, fluororesin films, polyimide films, aromatic polyamide films, acrylic (based) resin films, and polycarbonate films. A polyester film is preferable in terms of mechanical strength, smoothness, water resistance, solvent resistance, and heat resistance. These synthetic resin materials may be used alone or in combination of two or more.

  Examples of the polyester film include polyethylene terephthalate (PET), polybutylene terephthalate, poly-1,4-cyclohexanedimethylene terephthalate, polyxylylene terephthalate, polyethylene isophthalate, polyethylene-2,6-naphthalate (PEN). It is done. Preferred polyester films include PET films or PEN films that are excellent in toughness, heat resistance, chemical resistance, dimensional stability, transparency, and electrical insulation.

  The support may be opaque, translucent or transparent. In order to make the background appear white or other specific colors, a white pigment, a colored dye pigment, or air bubbles may be included in the support or on the surface. When the affinity when a coating layer such as a reversible thermosensitive recording layer is provided on the support is low, the support can be obtained by corona discharge treatment, oxidation reaction treatment (chromic acid, etc.), etching treatment, easy adhesion treatment, antistatic treatment, etc. A modification treatment may be performed on the surface. There is no restriction | limiting in particular about a shape, a structure, a magnitude | size, etc. as a support body concerning this invention. Examples of the shape include a flat plate shape and a roll shape. The structure may be a single layer structure or a laminated structure, and the size can be appropriately selected according to the use of the reversible thermosensitive recording material.

  The thickness of the support according to the present invention can be appropriately selected according to the use of the reversible thermosensitive recording material, but is preferably 10 to 2000 μm, and more preferably 20 to 1000 μm.

  The reversible thermosensitive recording layer according to the present invention is coated with a reversible thermosensitive recording layer coating solution containing at least a dye precursor, a reversible developer, and a decoloring accelerator on at least one surface of a support. It is formed by forming a film. As a method for including a dye precursor, a reversible developer, and a decoloring accelerator in a reversible thermosensitive recording layer coating solution, each compound is dissolved in a solvent alone or dispersed in a dispersion medium and then mixed. A method in which each compound is mixed and then dissolved in a solvent or dispersed in a dispersion medium, a method in which each compound is dissolved by heating, homogenized, cooled, and dissolved in a solvent or dispersed in a dispersion medium. However, it is not particularly limited. If necessary, a dispersing agent may be used during dispersion.

  As a solvent or dispersion medium, water; alcohols such as methanol, ethanol, n-propanol, 2-propanol, n-butanol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, isophorone; methyl acetate, ethyl acetate , Esters such as butyl acetate, isobutyl acetate, isopropyl acetate, ethyl lactate, ethylene carbonate, ethers such as diethyl ether, glycol dimethyl ether, glycol diethyl ether, dioxane, dioxolane, tetrahydrofuran, and fragrances such as benzene, toluene, xylene, and styrene Group hydrocarbons; aliphatic hydrocarbons such as pentane, hexane and cyclohexane; methylene chloride, ethylene chloride, carbon tetrachloride, chloroform, chlorobenzene Halogenated hydrocarbons such as dichlorobenzene; N, N- dimethylformamide, N, etc. amides such as N- dimethylacetamide can be used.

  For the purpose of improving the strength of the reversible thermosensitive recording layer, it is also possible to add a binder resin to the reversible thermosensitive recording layer. Specific examples of the binder resin include starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol, sodium polyacrylate, (meth) acrylic acid amide- (meth) acrylic acid ester copolymer Polymer, (meth) acrylic acid amide- (meth) acrylic acid ester- (meth) acrylic acid terpolymer, alkali salt of styrene-maleic anhydride copolymer, alkali salt of ethylene-maleic anhydride copolymer , Polyvinyl acetate, polyurethane, poly (meth) acrylic acid ester, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, methyl (meth) acrylate-butadiene copolymer, ethylene-vinyl acetate copolymer, ethylene -Salt Vinyl copolymers, polyvinyl chloride, ethylene - vinylidene chloride copolymer, polyvinylidene chloride, polycarbonates, polyvinyl butyral, and the like. The role of these binder resins is to keep the materials contained in the reversible thermosensitive recording layer uniformly dispersed without being displaced by heat application for image recording or image erasing. Therefore, it is preferable to use a resin having high heat resistance as the binder resin. When heat resistance, water resistance, and adhesiveness are required, a curable resin is particularly preferable.

  Examples of the curable resin include a thermosetting resin, an electron beam curable resin, and an ultraviolet curable resin. When a thermosetting resin is applied, a liquid containing a crosslinking agent is applied and formed into a film, and then crosslinked by heat. Specific examples of thermosetting resins include epoxy resins, urea resins, xylene-formaldehyde resins, melamine resins, guanamine resins, phenol resins, phenoxy resins, saturated polyester resins, unsaturated polyester resins, and polyol resins. In addition, examples of the curing agent used in these thermosetting resins include organic acids, amines, isocyanates, epoxies, phenols, and the like. It only has to be selected. Among these, a crosslinked resin obtained by thermally curing a polyol compound with an isocyanate compound described in JP-A Nos. 10-230680 and 11-58963 is preferable.

  As oligomers / monomers used for electron beam curable resins or UV curable resins, there are many types of acrylic oligomers / monomers with excellent radiation curing properties, polyene-thiol oligomers / monomers, and photocationic polymerization type epoxy. Examples include oligomers and monomers. Examples of the acrylic monomer include a monofunctional monomer, a bifunctional monomer, and a polyfunctional monomer. In particular, a photopolymerization initiator and a photopolymerization accelerator are used at the time of ultraviolet crosslinking.

  Examples of the acrylic oligomer / monomer include polyester acrylate, polyether acrylate, epoxy acrylate, polyurethane acrylate, silicone acrylate, melamine acrylate, polybutadiene acrylate, and the like.

  In the reversible thermosensitive recording layer according to the present invention, a binder resin formed by crosslinking a polyol compound and an isocyanate compound, which is a preferable binder resin, will be described. Examples of the polyol compound include poly (meth) acryl polyol, polyester polyol, polycarbonate polyol, polyester polycarbonate polyol, polyether polyol, alkyd polyol, caprolactone polyol, and silicone polyol.

  Poly (meth) acrylic polyol is a copolymer of acrylic acid, methacrylic acid, and esters thereof, which includes a hydroxyl group, and as a copolymer component containing a hydroxyl group, hydroxyethyl acrylate, methacrylic acid are included. Hydroxyethyl acid, hydroxypropyl acrylate, hydroxypropyl methacrylate, 3-chloro-2-hydroxypropyl acrylate, 3-chloro-2-hydroxypropyl methacrylate, allyl alcohol and the like are used. Examples of copolymer components other than acrylic acid, methacrylic acid, and esters thereof include styrene, α-methylstyrene, vinyltoluene, acrylamide, methacrylamide and derivatives thereof, vinyl acetate, and maleic anhydride.

  Polyester polyol refers to a condensate of a polybasic acid and a polyhydric alcohol having a hydroxyl group. Polybasic acids used in these are phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid. , Aromatic polybasic acids such as trimesic acid, pyromellitic acid, naphthalenedicarboxylic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, 2-methylsuccinic acid, 2-methyladipic acid, 3-methyladipic acid, 3-methylpentanedioic acid, 2-methyloctanedioic acid, 3,7-dimethyldecanedioic acid, 3,8-dimethyldecanedioic acid, There are aliphatic polybasic acids such as dimer acid, and acid anhydrides obtained from these polybasic acids are also used.

  Polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, propanediol, neopentyl glycol, glycerin, trimethylolethane, trimethylolpropane, diglycerol, pentaerythritol, dipentaerythritol, di In addition to low molecular weight polyols such as acetone glycol and hexanetriol, high molecular weight polyols such as polyethylene glycol, polypropylene glycol and polybutylene glycol are also used. In addition to the polyester polyols obtained from these, hydroxycarboxylic acids, or condensates or ring-opening polymerizations thereof of cyclic lactones such as polybutyrolactone polyols, polycaprolactone polyols, and higher fatty acids in addition to the above polybasic acids and polyhydric alcohols. There are alkyd polyols obtained by condensation. The polyether polyol is a polymer having a main chain composed of an ether bond, and includes polyethylene glycol, polypropylene glycol, polybutylene glycol, and these branched esters.

  In addition, fluorine-containing polyols such as hydroxyl-containing fluoroolefin, polyol hydroxyl-terminated polybutadiene, polyisoprene, hydrogenated polybutadiene, hydrogenated polyisoprene, polyurethane and the like can be used. Furthermore, low molecular weight polyols such as diethylene glycol, triethylene glycol, glycerol, trimethylolpropane, pentaerythritol, 1,4-cyclohexadiol, 1,4-dihydroxybenzene, bisphenol A, bisphenol F and other aliphatic, fatty A cyclic, aromatic polyhydric alcohol or polyhydric phenol or a condensate thereof is used as a reactive diluent.

  As the polyol compound according to the present invention, poly (meth) acrylic polyol and polyester polyol are preferable from the comprehensive evaluation of additive dispersibility, coating property, adhesiveness, heat resistance and film strength. The polyol compound according to the present invention may be used alone or in combination with one or more other polyol compounds having different polyol parts or other partial structures or different molecular weights.

  Further, poly (meth) acryl polyols and polyester polyol resins having a hydroxyl value of 80 (KOHmg / g) or more are preferably used, and particularly preferably 90 (KOHmg / g) to 500 (KOHmg / g). The magnitude of the hydroxyl value affects the crosslink density and thus affects the chemical resistance and physical properties of the coating film. When the hydroxyl value is 80 (KOHmg / g) or more, durability, coating surface hardness and crack resistance are improved.

  A well-known thing can be used as an isocyanate compound concerning this invention. For example, aromatic diisocyanates such as phenylene diisocyanate (PDI), toluene diisocyanate (TDI), naphthalene diisocyanate (NDI), 4,4'-diphenylmethane diisocyanate (MDI), xylylene diisocyanate (XDI), hydrogenated TDI, hydrogenated XDI , Hydrogenated MDI, hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI) and other aliphatic or alicyclic diisocyanates and their derivatives, polyol adducts, and burette trimers of trifunctional or higher functional polyisocyanates. In addition, various oligomers and polymers containing isocyanate are included. In the present invention, when xylylene diisocyanate or toluene isocyanate is used as the isocyanate compound, the color density is preferably improved, and further, xylylene diisocyanate having a high background whiteness is more preferable.

  The isocyanate compound according to the present invention may be used in combination with one or more isocyanates with respect to one or more polyol compounds. In the case where a plurality of isocyanate compounds and polyol compounds are used, the combination may be arbitrary.

  The mixture of the polyol compound and the isocyanate compound may be used as it is in the case where each is liquid, but it can also be used after diluted with a non-reactive solvent with the isocyanate compound. As a solvent that can be used, a solvent that dissolves a polyol compound and an isocyanate compound and disperses and dissolves a dye precursor and a reversible developer is preferable. Specifically, the solvent illustrated by the method for making a reversible thermosensitive recording layer coating liquid contain a dye precursor and a reversible color developer can be used. Especially, it is preferable to use the organic solvent which does not have active hydrogen reactive with an isocyanate compound. The crosslinking reaction between the polyol compound and the isocyanate compound may be performed at a reaction temperature of 30 to 160 ° C. and a reaction time of 1 minute to 120 hours. Needless to say, it takes a long time when the reaction temperature is low, and a short time at a high temperature.

  The amount of binder resin used in the reversible thermosensitive recording layer according to the present invention is preferably such that the mass percentage of the binder resin relative to the total mass of the reversible thermosensitive recording layer is in the range of 35% to 65%. If it is larger than this range, the color density may decrease significantly. On the other hand, if it is smaller than this range, the heat resistance and mechanical strength of the reversible thermosensitive recording layer may be lowered, the layer may be deformed, and the color density may be lowered. The mass percentage of the binder resin in the reversible thermosensitive recording layer is more preferably 40% to 60%, and particularly preferably 45% to 55%.

  For a reversible thermosensitive recording layer coating liquid, a leveling agent, a dispersant, a hardener, a surfactant, a thickener, and an antifoaming agent are used for the purpose of improving coating properties or recording characteristics as necessary. Anti-aging agents, fillers, pigments, lubricants, antistatic agents, infrared absorbers, coloring dyes, fluorescent whitening agents, thermofusible substances, preservatives, and the like can be incorporated into the reversible thermosensitive recording layer.

  Antioxidants such as hindered phenolic antioxidants, phosphorus antioxidants, sulfur antioxidants, vitamins A, vitamin C, vitamin E, etc., for the purpose of improving the weather resistance of the reversible thermosensitive recording layer , Hindered amine light stabilizers, benzophenone UV absorbers, benzotriazole UV absorbers, triazine UV absorbers, benzoate UV absorbers, salicylate UV absorbers, cinnamate UV absorbers, etc. May be added. Of these, hindered phenol antioxidants, benzotriazole ultraviolet absorbers, and triazine ultraviolet absorbers are preferred. These may be used individually by 1 type, and 2 or more types may be mixed and used for them. The usage-amount with respect to a dye precursor is 0.1-200 mass%, Preferably it is 0.5-100 mass%, Most preferably, it is 1-50 mass%. When the amount used is less than 0.1% by mass, the effect of improving the weather resistance may not be exhibited. When the amount used exceeds 200% by mass, the color density may decrease and the heat stability of the printed image may decrease. .

  When the reversible thermosensitive recording layer contains a curable resin, heating, ultraviolet irradiation, and electron beam irradiation are performed. Ultraviolet irradiation can be performed using a known ultraviolet irradiation device, and examples thereof include a light source, a lamp, a power source, a cooling device, and a conveying device. Examples of the light source include a mercury lamp, a metal halide lamp, a gallium lamp, a mercury xenon lamp, and a flash lamp. The wavelength of the light source can be appropriately selected according to the ultraviolet absorption wavelength of the photopolymerization initiator and the photopolymerization accelerator. The output and conveying speed of the ultraviolet irradiation are determined according to the irradiation energy necessary for crosslinking the ultraviolet curable resin.

  As the heat-fusible substance which is an additive for adjusting the color development sensitivity and / or decoloring temperature of the reversible thermosensitive recording layer, those having a melting point of 60 ° C. to 200 ° C. are preferable, and in particular, 80 ° C. to 180 ° C. Those having a melting point of Sensitizers used for general heat-sensitive recording paper can also be used. For example, naphthol derivatives such as 2-benzyloxynaphthalene, biphenyl derivatives such as p-benzylbiphenyl and 4-allyloxybiphenyl, 1,2-bis (3-methylphenoxy) ethane, 2,2′-bis (4-methoxy Add together with polyether compounds such as phenoxy) diethyl ether and bis (4-methoxyphenyl) ether, carbonic acid or oxalic acid diester derivatives such as diphenyl carbonate, dibenzyl oxalate, and bis (p-methylbenzyl) oxalate. can do.

  Anti-aging agents added for the purpose of preventing aging of the reversible thermosensitive recording layer include amine compounds such as p, p'-diaminodiphenylmethane, aldol-α-naphthylamine, and N, N'-diphenyl-p-phenylenediamine. , Hydroquinone monobenzyl ether, phenol compounds such as 1,1-bis (p-hydroxyphenyl) cyclohexane, benzotriazole compounds, triazine compounds, benzophenone compounds, benzoates and the like. In addition, o-phenylenethiourea, zinc salt of 2-aminobenzimidazole, nickel dibutylthiocarbamate, zinc oxide, paraffin and the like can be mentioned. In addition, a polymer containing these monomers having an anti-aging structure as a component of polymerization, and a polymer main chain grafted with an anti-aging structure can also be used. Two or more types of anti-aging agents can be used in combination.

  Examples of pigments that can be added to the reversible thermosensitive recording layer include, for example, carbonates such as aluminum, zinc, calcium, magnesium, barium, and titanium, oxides, hydroxides, sulfates, and zeolites, silica, Inorganic pigments containing clays such as kaolin, calcined kaolin and talc, starch, styrene resin, polyolefin resin, urea-formalin resin, melamine resin, acrylic resin, paraffin, natural wax, synthetic wax and the like can be used. Further, higher fatty acid metal salts such as zinc stearate and calcium stearate can be used as a lubricant.

  The film thickness of the reversible thermosensitive recording layer according to the present invention is determined by its composition and desired color density, and specifically, it is preferably in the range of 0.5 to 20 μm, more preferably 3 to 15 μm. .

  In the present invention, it is preferable to provide a protective layer on the reversible thermosensitive recording layer for the purpose of enhancing durability during repeated use. The protective layer may be composed of a single layer or a plurality of layers of two layers or three or more layers. The protective layer preferably contains a curable resin such as a thermosetting resin, an electron beam curable resin, or an ultraviolet curable resin, and particularly preferably an electron beam curable resin or an ultraviolet curable resin. As the curable resin, resins exemplified as binder resins that can be used in the reversible thermosensitive recording layer can be used. Further, a pigment may be blended for the purpose of further improving durability or adjusting the glossiness, or a higher fatty acid metal salt or the like may be blended as a lubricant. As the pigment and the higher fatty acid metal salt, the compounds exemplified in the reversible thermosensitive recording layer can be used.

  The thickness of the protective layer is preferably in the range of 0.1 to 10 μm, more preferably 0.5 to 5 μm. When the film thickness exceeds 10 μm, not only the effect is saturated, but also the sensitivity of the reversible thermosensitive recording layer tends to decrease. When the film thickness is smaller than 0.1 μm, it is difficult to obtain the expected coating layer strength, and the coating layer is easily damaged.

  In the present invention, an intermediate layer is provided between the reversible thermosensitive recording layer and the protective layer for the purpose of improving weather resistance or the like, or an undercoat layer is provided between the support and the reversible thermosensitive recording layer for the purpose of improving the color development sensitivity. Alternatively, a light reflection layer or an air layer may be provided. The intermediate layer may contain an ultraviolet absorber. In the case where the reversible thermosensitive recording layer is provided only on one side of the support, a back coat layer may be provided on the other side. As ultraviolet absorbers, organic ultraviolet absorbers such as benzophenone ultraviolet absorbers, benzotriazole ultraviolet absorbers, triazine ultraviolet absorbers, benzoate ultraviolet absorbers, salicylate ultraviolet absorbers, cinnamate ultraviolet absorbers, Or inorganic ultraviolet absorbers, such as zinc oxide, cerium oxide, iron oxide, and titanium oxide, can be mentioned. The undercoat layer may contain hollow particles. These layers may be composed of a single layer or a plurality of layers of two or more layers. Moreover, it is preferable that these layers contain curable resins, such as a thermosetting resin, an electron beam curable resin, and an ultraviolet curable resin.

  The reversible thermosensitive recording material of the present invention may be provided with a printing recording layer such as printing such as offset printing or gravure printing; an ink jet recording layer, a thermal transfer image receiving layer, a sublimation thermal transfer image receiving layer. These print and print recording layers may be provided by being laminated with the reversible thermosensitive recording layer, or may be provided on a part of the same surface as the reversible thermosensitive recording layer. Further, it may be provided on a part of or the entire surface opposite to the surface on which the reversible thermosensitive recording layer is provided. An overprint varnish (OP varnish) layer mainly composed of a curable resin may be provided partially or entirely on the print recording layer.

  In the reversible thermosensitive recording material of the present invention, in the reversible thermosensitive recording layer, other layers, the surface provided with the reversible thermosensitive recording layer, the opposite surface, etc. are electrically, magnetically and optically information. May contain a recordable material. Further, the support may be a multilayer and an IC chip may be sandwiched between them. Further, a heat-sealing layer can be provided on the surface opposite to the surface on which the reversible thermosensitive recording layer is provided, and can be attached to another medium.

  In the present invention, a protective layer, an intermediate layer, an undercoat layer, a backcoat layer, and a heat fusion layer provided on a support are optionally provided with a leveling agent, a dispersant, a hardener, and a surfactant. , Thickeners, hardeners, preservatives, fillers, coloring dyes, fluorescent brighteners, UV absorbers, infrared absorbers, antioxidants, anti-aging agents, pH adjusters, antifoaming agents, pigments, lubricants Various additives such as an antistatic agent can be added.

  When the IC chip is encapsulated between the layers of the reversible thermosensitive recording material, for example, it can be encapsulated between the layers of the plastic film or between the paper substrate and the plastic film. It is preferable from the viewpoint of print quality that sealing is performed between layers away from the reversible thermosensitive recording layer. When a non-contact IC chip is encapsulated, it can be encapsulated with an antenna. A cushion layer can be provided for the purpose of preventing the IC chip from being damaged by the pressure during encapsulation. The thickness of the cushion layer is preferably 10 μm or more because cushioning properties are insufficient if it is less than 10 μm. In addition, since a load is applied to the joint between the IC chip and the antenna, the area of the cushion layer is preferably large enough to cover the IC chip and the antenna joint. The cushion layer can be provided on one side or both sides. More preferably, cushion layers are provided on both sides. As the cushion layer, a thermoplastic resin is preferable. The foamed resin has better cushioning properties and can prevent the IC chip from being damaged.

  The method of laminating each layer in the present invention on a support to form a reversible thermosensitive recording material is not particularly limited, and can be formed by a conventional method. For example, air knife coater, blade coater, bar coater, curtain coater, gravure roll and transfer roll coater, roll coater, comma coater, smoothing coater, micro gravure coater, reverse roll coater, 4 roll roll coater, dip coater, Various coating machines such as a rod coater, a kiss coater, a gate roll coater, a squeeze coater, a slide coater, a die coater and other smearing apparatuses, a planographic plate, a relief plate, an intaglio plate, a flexo, a gravure, a screen, and a hot melt can be used. Furthermore, each layer can be held by ultraviolet ray irradiation or electron beam irradiation, aging by heating, etc. in addition to the usual drying step. By these methods, it is possible to apply and print one layer at a time or multiple layers simultaneously.

  In the reversible thermosensitive recording material of the present invention, rapid cooling is required following heating to form a color-recorded recording image, and a slow cooling rate after heating is sufficient to erase the recorded image. For example, after heating by an appropriate method, a colored state can be developed by rapidly cooling by pressing a low-temperature metal block or the like. In addition, if the heating is performed for a very short time using a thermal head, laser light, or the like, the cooling is performed immediately after the heating is completed, so that the colored state can be maintained. On the other hand, when heated for a relatively long time with a suitable heat source (thermal head, laser light, heat roll, heat stamp, high-frequency heating, electric heater, radiant heat from a light source such as a tungsten lamp or halogen lamp, hot air, etc.) Since not only the layer but also the support and the like are heated, even if the heat source is removed, the cooling rate is slow, and the color is lost. Therefore, even when the same heating temperature and the same heat source are used, the coloring state and the decoloring state can be arbitrarily developed by controlling the cooling rate.

  Examples of the laser used for heating include, but are not limited to, a semiconductor laser, a YAG laser, and a carbon dioxide gas laser. In order to efficiently perform heating with a semiconductor laser or a YAG laser, a reversible thermosensitive recording layer contains a photothermal conversion material having absorption in the near infrared region, or a photothermal conversion layer containing a photothermal conversion material is reversible. It is preferably provided directly adjacent to the thermal recording layer. Examples of photothermal conversion materials having absorption in the near infrared region include, for example, metal or metalloid layers such as platinum, titanium, silicon, chromium, nickel, germanium, and aluminum, immonium compounds, metal complex compounds, cyanine dyes, squarylium dyes, Photothermal conversion dyes such as naphthoquinone dyes, phthalocyanine compounds, and polymethine compounds can be used, and can be contained in the reversible thermosensitive recording layer in a dispersed state or in a molecular state. Preferable photothermal conversion dyes include phthalocyanine compounds and metal complex compounds in terms of photothermal conversion efficiency, solubility in solvents, dispersibility in resins, and light resistance to ultraviolet light, and phthalocyanine compounds are particularly preferable. When the photothermal conversion layer is provided in the vicinity of the reversible thermosensitive recording layer, a photothermal conversion layer made of a metal film such as a copper thin film or ITO can also be used.

  Examples of phthalocyanine compounds include naphthalocyanine compounds, metal-free phthalocyanine compounds, iron phthalocyanine compounds, copper phthalocyanine compounds, zinc phthalocyanine compounds, nickel phthalocyanine compounds, vanadyl phthalocyanine compounds, indium chloride phthalocyanine compounds, tin phthalocyanine compounds, and more preferably. Are vanadyl phthalocyanine compounds, zinc phthalocyanine compounds, and tin phthalocyanine compounds. The phthalocyanine compound used in the present invention may have a substituent on the aromatic ring for the purpose of adjusting the absorption wavelength, improving the solubility in a solvent, improving light resistance, and the like. Examples of the substituent include an alkyl ether group, an alkyl thioether group, an aryl ether group, an aryl thioether group, an amide group, an amino group, an alkyl ester group, an aryl ester group, a chlorine atom, and a fluorine atom. When there are two or more substituents on the aromatic ring, they may be the same or different, and the substituents may be bonded to form a ring.

  The amount of the photothermal conversion dye used is preferably set so that the absorbance at the oscillation wavelength of the light source used is 0.2 or more. If it is less than this amount, sufficient heat generation cannot be obtained, and the recording sensitivity is lowered. On the other hand, the photothermal conversion dye has some absorption in the visible region, and if the amount used is too large, the contrast is lowered. It is preferable to set an upper limit for the amount of photothermal conversion dye used so that an average transmittance of 400 nm to 700 nm can be secured by 60% or more. Two or more kinds of photothermal conversion dyes can be mixed and used.

  The photothermal conversion dye is preferably contained in at least one of the same layer or adjacent layers with respect to the layer containing the leuco dye and the reversible developer, and preferably contained in the same layer. It is more preferable for obtaining sensitivity.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited to this Example. In addition, the number of parts in an Example is a mass reference | standard.

Example 1
(A) Preparation of reversible thermosensitive recording layer coating solution 20 parts of 2-anilino-3-methyl-6-diethylaminofluorane as a dye precursor and N- [3- (p-hydroxyphenyl) as a reversible developer ) Propiono] -N'-docosanohydrazide 100 parts, as decolorization accelerator, 20 parts behenamide, polyester polyol (manufactured by DIC Corporation, trade name: Bernock 11-408, active ingredient: 70% by mass) 100 Part and a mixture of 950 parts of methyl ethyl ketone were dispersed with a glass bead for 12 hours using a paint shaker to obtain a dispersion. To the dispersion thus obtained, 130 parts of an isocyanate compound (manufactured by Mitsui Chemicals, trade name: Takenate D-110N, active ingredient: 75% by mass) and 62 parts of methyl ethyl ketone are added and mixed well, and reversible thermosensitive. A recording layer coating solution was prepared.

(B) Coating of reversible thermosensitive recording layer coating liquid The reversible thermosensitive recording layer coating liquid obtained in (A) is applied to a white polyethylene terephthalate (PET) sheet having a thickness of 125 μm in a dry coating amount of 10 g / m ^2. Then, after drying at 100 ° C. for 1 minute, it was further cured by heating at 50 ° C. for 24 hours to form a reversible thermosensitive recording layer.

(C) Preparation of intermediate layer coating solution 50 parts of 2,2'-methylenebis [6- (2H-benzotriazol-2-yl) -4- (2-hydroxyethyl) phenol] as a UV absorber, polyester polyol (DIC) Co., Ltd., trade name: Bernock 11-408, active ingredient 70 mass%) 100 parts and a mixture of 800 parts of methyl ethyl ketone were dispersed together with glass beads for 5 hours with a paint shaker to obtain a dispersion. To the dispersion thus obtained, 140 parts of an isocyanate compound (trade name: Takenate D-110N, active ingredient 75% by mass, manufactured by Mitsui Chemicals, Inc.) and 50 parts of methyl ethyl ketone were added and mixed well, and the intermediate layer was coated. A liquid was prepared.

(D) Coating of intermediate layer coating liquid On the reversible thermosensitive recording layer coated surface of the coated sheet prepared in (B), the dry coating amount of the intermediate layer coating liquid obtained in (C) is 2 g / m ^2. And dried at 100 ° C. for 1 minute, and further cured by heating at 50 ° C. for 24 hours to provide an intermediate layer.

(E) Preparation of coating liquid for protective layer Urethane acrylate UV curable resin (manufactured by DIC Corporation, trade name: Unidic V-4025, active ingredient: 80% by mass) 12.5 parts, wet process silica (Fuji Silysia Chemical) (Trade name) manufactured by Co., Ltd., trade name: Cylicia 350) 1.0 part, 0.5 part of 1-butyl-3-methylpyridinium dicyanamide, and 10 parts of butyl acetate were mixed. The liquid mixture thus obtained was treated with a bead mill to prepare a protective layer coating solution.

(F) Coating of protective layer coating liquid On the intermediate layer coating surface of the coating sheet prepared in (D), the dry coating amount of the protective layer coating liquid obtained in (E) is 3 g / m ^2. The film is dried at 120 ° C. for 1 minute, and then cured by passing it through an ultraviolet lamp with a lamp output of 120 W / cm at a conveying speed of 10 m / min to provide a protective layer. The reversible thermosensitive recording material of Example 1 Got.

(Example 2)
The reversibility of Example 2 was the same as Example 1 except that the amount of 1-butyl-3-methylpyridinium dicyanamide added was changed from 0.5 part to 2.0 parts in Example 1 (E). A heat-sensitive recording material was obtained.

(Example 3)
Example 1 Example (E) except that 0.5 part of 1-ethyl-3-methylimidazolium dicyanamide was used instead of 0.5 part of 1-butyl-3-methylpyridinium dicyanamide. In the same manner as in Example 1, a reversible thermosensitive recording material of Example 3 was obtained.

Example 4
Example 1 Example (E) except that instead of using 0.5 part of 1-butyl-3-methylpyridinium dicyanamide, 2.0 part of 1-ethyl-3-methylimidazolium dicyanamide was used. In the same manner as in Example 1, a reversible thermosensitive recording material of Example 4 was obtained.

(Example 5)
In Example 1 (E), Example 1 and Example 1 were used except that 0.5 part of benzyldimethyl-n-dodecylammonium dicyanamide was used instead of 0.5 part of 1-butyl-3-methylpyridinium dicyanamide. Similarly, a reversible thermosensitive recording material of Example 5 was obtained.

(Comparative Example 1)
A reversible thermosensitive recording material of Comparative Example 1 was obtained in the same manner as in Example 1 except that 0.5 part of 1-butyl-3-methylpyridinium dicyanamide was not added in Example 1 (E). .

(Comparative Example 2)
In Example 1 (E), instead of using 0.5 part of 1-butyl-3-methylpyridinium dicyanamide, tri-n-butylmethylammonium bistrifluoromethanesulfonimide (manufactured by Sumitomo 3M Limited, product name) : FC-4400) A reversible thermosensitive recording material of Comparative Example 2 was obtained in the same manner as in Example 1 except that 0.5 part was used.

(Comparative Example 3)
In Example 1 (E), instead of using 0.5 part of 1-butyl-3-methylpyridinium dicyanamide, tri-n-butylmethylammonium bistrifluoromethanesulfonimide (manufactured by Sumitomo 3M Limited, product name) : FC-4400) A reversible thermosensitive recording material of Comparative Example 3 was obtained in the same manner as in Example 1 except that 2.0 parts were used.

(Comparative Example 4)
In Example 1 (E), instead of using 0.5 part of 1-butyl-3-methylpyridinium dicyanamide, 0.5 part of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate was used. In the same manner as in Example 1, a reversible thermosensitive recording material of Comparative Example 4 was obtained.

(Comparative Example 5)
In Example 1 (E), instead of using 0.5 parts of 1-butyl-3-methylpyridinium dicyanamide, 2.0 parts of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate was used. In the same manner as in Example 1, a reversible thermosensitive recording material of Comparative Example 5 was obtained.

(Example 6)
(G) Preparation of coating solution for protective layer Urethane acrylate UV curable resin (manufactured by DIC Corporation, trade name: Unidic V-4025, active ingredient: 80% by mass) 12.5 parts, wet process silica (Fuji Silysia Chemical) 1.0 part by a product made from Co., Ltd. and a brand name: Cylicia 350) and 10 parts of butyl acetate were mixed. The liquid mixture thus obtained was treated with a bead mill to prepare a protective layer coating solution.

(H) Coating of protective layer coating liquid On the intermediate layer coating surface of the coating sheet prepared in (D), the protective layer coating liquid obtained in (G) is dried so that the dry coating amount is 3 g / m ^2. The film was dried at 120 ° C. for 1 minute, and then cured by passing under an ultraviolet lamp with a lamp output of 120 W / cm at a conveyance speed of 10 m / min to provide a protective layer.

(I) Preparation of Backcoat Layer Coating Liquid Urethane acrylate UV curable resin (manufactured by DIC Corporation, trade name: Unidic V-4025, active ingredient: 80% by mass), 12.5 parts, wet process silica (Fuji Silysia) Chemical Co., Ltd., trade name: Cylicia 350) 1.0 part, 1-butyl-3-methylpyridinium dicyanamide 0.5 part, butyl acetate 10 parts were mixed. The mixed solution thus obtained was treated with a bead mill to prepare a backcoat layer coating solution.

(J) Application of backcoat layer coating liquid The backcoat layer coating liquid obtained in (I) is dried on the opposite PET provided with the reversible thermosensitive recording layer surface of the coating sheet prepared in (H). After coating at a work rate of 3 g / m ² and drying at 120 ° C. for 1 minute, the back coat layer was cured by passing under an ultraviolet lamp with a lamp output of 120 W / cm at a conveying speed of 10 m / min. And a reversible thermosensitive recording material of Example 6 was obtained.

(Example 7)
The reversibility of Example 7 was the same as Example 6 except that the amount of 1-butyl-3-methylpyridinium dicyanamide added was changed from 0.5 part to 2.0 parts in Example 6 (I). A heat-sensitive recording material was obtained.

(Example 8)
In Example 6 (I), except that 0.5 part of 1-butyl-3-methylpyridinium dicyanamide was used, 0.5 part of 1-ethyl-3-methylimidazolium dicyanamide was used. In the same manner as in Example 6, a reversible thermosensitive recording material of Example 8 was obtained.

Example 9
In Example 6 (I), except that 0.5 part of 1-butyl-3-methylpyridinium dicyanamide was used, 2.0 part of 1-ethyl-3-methylimidazolium dicyanamide was used. In the same manner as in Example 6, a reversible thermosensitive recording material of Example 9 was obtained.

(Example 10)
In Example 6 (I), Example 6 was repeated except that 0.5 part of benzyldimethyl-n-dodecylammonium dicyanamide was used instead of 0.5 part of 1-butyl-3-methylpyridinium dicyanamide. Similarly, a reversible thermosensitive recording material of Example 10 was obtained.

(Example 11)
Example 1 (F) On the opposite PET provided with the reversible thermosensitive recording layer surface of the prepared coated sheet, the backcoat layer coating solution obtained in Example 6 (I) had a dry coating amount of 3 g / m. ² and dried at 120 ° C. for 1 minute, followed by curing under an ultraviolet lamp with a lamp output of 120 W / cm at a conveying speed of 10 m / min to provide a backcoat layer. A reversible thermosensitive recording material was obtained.

(Comparative Example 6)
A reversible thermosensitive recording material of Comparative Example 6 was obtained in the same manner as in Example 6 except that 0.5 part of 1-butyl-3-methylpyridinium = dicyanamide was not added in Example 6 (I). .

(Comparative Example 7)
In Example 6 (I), instead of using 0.5 part of 1-butyl-3-methylpyridinium dicyanamide, tri-n-butylmethylammonium bistrifluoromethanesulfonimide (manufactured by Sumitomo 3M Limited, trade name) : FC-4400) A reversible thermosensitive recording material of Comparative Example 7 was obtained in the same manner as in Example 6 except that 0.5 part was used.

(Comparative Example 8)
In Example 6 (I), instead of using 0.5 part of 1-butyl-3-methylpyridinium dicyanamide, 0.5 part of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate was used. In the same manner as in Example 6, a reversible thermosensitive recording material of Comparative Example 8 was obtained.

(Example 12)
(K) Preparation of heat-sealable layer coating solution Polyester resin hot melt adhesive (manufactured by Toagosei Co., Ltd., trade name: Aronmelt PES-360S30, active ingredient: 30% by mass) 35 parts, 1-butyl-3- Methylpyridinium = dicyanamide (0.5 parts) was mixed well to prepare a heat fusion layer coating solution.

(L) Application of heat-sealable layer coating solution The heat-sealable layer obtained in (K) on the opposite PET provided with the reversible thermosensitive recording layer surface of the coated sheet prepared in Example 1 (F). The coating liquid was applied such that the dry coating amount was 7 g / m ² and dried at 100 ° C. for 1 minute to provide a heat-sealing layer, whereby a reversible thermosensitive recording material of Example 12 was obtained.

(Example 13)
The reversibility of Example 13 was the same as Example 12 except that the amount of 1-butyl-3-methylpyridinium dicyanamide added was changed from 0.5 part to 2.0 parts in Example 12 (K). A heat-sensitive recording material was obtained.

(Example 14)
In Example 12 (K), instead of using 0.5 part of 1-butyl-3-methylpyridinium dicyanamide, Example 12 except that 0.5 part of 1-ethyl-3-methylimidazolium dicyanamide was used. In the same manner as described above, a reversible thermosensitive recording material of Example 14 was obtained.

(Example 15)
Example 12 Example (K) except that instead of using 0.5 part of 1-butyl-3-methylpyridinium dicyanamide, 2.0 part of 1-ethyl-3-methylimidazolium dicyanamide was used. 12, a reversible thermosensitive recording material of Example 15 was obtained.

(Example 16)
In Example 12 (K), Example 12 was repeated except that 0.5 part of benzyldimethyl-n-dodecylammonium dicyanamide was used instead of 0.5 part of 1-butyl-3-methylpyridinium dicyanamide. Similarly, a reversible thermosensitive recording material of Example 16 was obtained.

(Comparative Example 9)
(M) Preparation of heat fusion layer coating liquid Polyester resin hot melt adhesive (manufactured by Toagosei Co., Ltd., trade name: Aronmelt PES-360S30, active ingredient: 30% by mass) 35 parts, tri-n-butylmethyl 0.5 parts of ammonium = bistrifluoromethanesulfonimide (manufactured by Sumitomo 3M Co., Ltd., trade name: FC-4400) was mixed well to prepare a heat-sealing layer coating solution.

(N) Application of heat-sealable layer coating solution The heat-sealable layer obtained in (M) on the opposite PET provided with the reversible thermosensitive recording layer surface of the coated sheet prepared in Example 6 (H). The coating liquid was applied so that the dry coating amount was 7 g / m ² and dried at 100 ° C. for 1 minute to provide a heat-sealing layer, whereby a reversible thermosensitive recording material of Comparative Example 9 was obtained.

(Comparative Example 10)
In Comparative Example 9 (M), the addition amount of tri-n-butylmethylammonium bistrifluoromethanesulfonimide (manufactured by Sumitomo 3M Ltd., trade name: FC-4400) was changed from 0.5 part to 2.0 parts. A reversible thermosensitive recording material of Comparative Example 10 was obtained in the same manner as Comparative Example 9, except that the changes were made.

(Comparative Example 11)
Instead of using 0.5 part of tri-n-butylmethylammonium bistrifluoromethanesulfonimide (manufactured by Sumitomo 3M Limited, trade name: FC-4400) in Comparative Example 9 (M), 1-ethyl-3 A reversible thermosensitive recording material of Comparative Example 11 was obtained in the same manner as Comparative Example 9, except that 0.5 part of methyl imidazolium = trifluoromethanesulfonate was used.

(Comparative Example 12)
A polyester resin-based hot melt adhesive (manufactured by Toagosei Co., Ltd., trade name: Aron Melt PES-360S30) on the opposite PET provided with the reversible thermosensitive recording layer surface of the coated sheet prepared in Example 6 (H). , Active ingredient: 30% by mass) is dried so as to have a dry coating amount of 7 g / m ² , dried at 100 ° C. for 1 minute to provide a heat-sealing layer, and the reversible thermosensitive recording material of Comparative Example 12 Got.

  An evaluation test was performed on the reversible thermosensitive recording material produced as described above. The results are as shown in Table 1. Each evaluation item was implemented as follows.

[Surface resistivity]
The surface resistivity of the reversible thermosensitive recording materials of Examples 1 to 16 and Comparative Examples 1 to 12 was measured in a resistivity measurement cell (trade name: 16008A, Yokogawa Hewlett-Packard Co., Ltd.) in an environment of 23 ° C. and 50% RH. Measured by a high resistivity measuring instrument (trade name: 4329A, manufactured by Yokogawa Hewlett-Packard Co., Ltd.). The applied voltage was 100 V, and the heating time was 60 seconds. The measurement was performed on both the recording surface (front surface) of the reversible thermosensitive recording material and its half-facing surface (back surface). The results are shown in the “surface resistance value” column of Table 1.

[Sheets between sheets]
The reversible thermosensitive recording materials of Examples 1 to 11 and Comparative Examples 1 to 8 were cut into A4 size sheets, and the same using a printer (trade name: B-SX8R-TS15, manufactured by Toshiba TEC Corporation). Ten A4 sheets of reversible thermosensitive recording material were continuously erased and printed. Here, the erasure printing is one in which the reversible thermosensitive recording material is first erased and then processed in the order of printing, and the image is rewritten. Erasing is performed with a heat roll, and printing is performed with a thermal head of about 305 dpi. The conditions were an erasing temperature of 170 ° C. and a printing speed of 2 inches / second. The sheets on which erasure printing was completed were overlapped so that the printing surface (front side) and the opposite surface (back side) were in close contact with each other. After standing for 10 minutes, the superimposed sheets were continuously erased and printed again using the printer, and the sheet conveyance failure was evaluated. The process from erasure printing to evaluation was performed in an environment of 23 ° C. and 50% RH. The results are shown in the “sheet conveyance” column of Table 1. In Table 1, ○ indicates that there is no conveyance failure, Δ indicates that double feeding of two or more sheets out of 10 sheets occurs once, and x indicates that the double feeding occurs twice or more. .

[Repeat Print / Erase]
The reversible thermosensitive recording materials of Examples 1 to 11 and Comparative Examples 1 to 8 are cut into A4 size sheets, and are erased and printed using a printer (trade name: B-SX8R-TS15, manufactured by Toshiba TEC Corporation). Went. The erasing temperature was 170 ° C., the printing speed was 2 inches / second, and erasing printing was repeated 30 times at intervals of 5 minutes on one sheet.

  The optical density of the printed part at the 30th time was measured with a reflection densitometer (trade name: RD-19, manufactured by GretagMacbeth). The results are shown in the “print density” column of Table 1. Further, the printed surface was observed to evaluate the presence or absence of printing defects due to adhesion of foreign matters such as dust. The results are shown in the “Printing Missing” column of Table 1.

[Printing ink fillability]
For the printing surface (front surface) and the opposite surface (back surface) of the reversible thermosensitive recording materials of Examples 1 to 11 and Comparative Examples 1 to 8, the printability tester (trade name “RI-1”, Ishikawajima Ink fillability test was carried out using an industrial machine. The printing ink was offset UV ink (trade name “Best Cure Vector HD Process Black”, manufactured by T & K TOKA Corporation), and 5 ml of ink was used per test. The image after printing was cured by passing under an ultraviolet lamp with a lamp output of 80 W / cm at a conveyance speed of 10 m / min, and then the optical density was measured with a reflection densitometer (trade name “RD-19”, manufactured by Gretag Macbeth). Measured and evaluated to 4 levels. In the four-level classification, a density of 1.2 or higher was evaluated as ◎, 1.0 or higher and lower than 1.2 as ◯, 0.8 or higher and lower than 1.0 as Δ, and less than 0.8 as X. The higher the concentration, the better the ink deposition property, and the greater the effect of the present invention.

(Example 17)
(O) Preparation of heat-sealable layer-coated PET sheet A polyester resin hot melt adhesive (trade name: Aron Melt PES-360S30, effective by white polyethylene terephthalate (PET) sheet having a thickness of 125 μm, effective Ingredient: 30% by mass) was applied so that the dry coating amount was 7 g / m ² and dried at 100 ° C. for 1 minute to provide a heat-sealing layer to obtain a heat-sealing layer-coated PET sheet. .

(P) Heat press with heat-sealable layer-coated PET sheet Reversible thermosensitive recording material prepared in Example 12, white vinyl chloride (PVC) sheet having a thickness of 200 μm, and heat-seal prepared with (O) Layer-coated PET sheets are stacked in this order so that the heat-bonding layer-coated surfaces are on the inside, and a heat press machine (trade name: desktop test press SA-303, manufactured by Tester Sangyo Co., Ltd.) is used. Using this, hot pressing was performed under the conditions of temperature: 130 ° C., pressure: 1 kN / m ² , time: 15 minutes, and the reversible thermosensitive recording material of Example 17 was obtained.

(Example 18)
Example 17 (P) was carried out in the same manner as in Example 17 except that the reversible thermosensitive recording material prepared in Example 12 was used instead of the reversible thermosensitive recording material prepared in Example 12. The reversible thermosensitive recording material of Example 18 was obtained.

(Example 19)
Example 17 (P) was carried out in the same manner as in Example 17 except that the reversible thermosensitive recording material produced in Example 12 was used instead of the reversible thermosensitive recording material produced in Example 12. The reversible thermosensitive recording material of Example 19 was obtained.

(Example 20)
Example 17 (P) was carried out in the same manner as in Example 17 except that the reversible thermosensitive recording material produced in Example 12 was used instead of the reversible thermosensitive recording material produced in Example 12. The reversible thermosensitive recording material of Example 20 was obtained.

(Example 21)
Example 17 (P) was carried out in the same manner as in Example 17 except that the reversible thermosensitive recording material produced in Example 12 was used instead of the reversible thermosensitive recording material produced in Example 12. The reversible thermosensitive recording material of Example 21 was obtained.

(Comparative Example 13)
In Example 17 (P), a comparison was made in the same manner as in Example 17 except that the reversible thermosensitive recording material produced in Example 12 was used instead of the reversible thermosensitive recording material produced in Example 12. The reversible thermosensitive recording material of Example 13 was obtained.

(Comparative Example 14)
In Example 17 (P), a comparison was made in the same manner as in Example 17 except that the reversible thermosensitive recording material prepared in Example 12 was used instead of the reversible thermosensitive recording material prepared in Example 12. The reversible thermosensitive recording material of Example 14 was obtained.

(Comparative Example 15)
In Example 17 (P), a comparison was made in the same manner as in Example 17 except that the reversible thermosensitive recording material produced in Example 12 was used instead of the reversible thermosensitive recording material produced in Example 12. The reversible thermosensitive recording material of Example 15 was obtained.

(Comparative Example 16)
In Example 17 (P), a comparison was made in the same manner as in Example 17 except that the reversible thermosensitive recording material produced in Example 12 was used instead of the reversible thermosensitive recording material produced in Example 12. The reversible thermosensitive recording material of Example 16 was obtained.

  An evaluation test was performed on the reversible thermosensitive recording material produced as described above. The results are as shown in Table 2. Each evaluation item was implemented as follows.

[Surface resistivity]
The surface resistivity of the reversible thermosensitive recording materials of Examples 17 to 21 and Comparative Examples 13 to 16 was measured in a resistivity measurement cell (trade name: 16008A, Yokogawa Hewlett-Packard Co., Ltd.) in an environment of 23 ° C. and 50% RH. Measured by a high resistivity measuring instrument (trade name: 4329A, manufactured by Yokogawa Hewlett-Packard Co., Ltd.). The applied voltage was 100 V, and the heating time was 60 seconds. The measurement was performed on both the recording surface (front surface) of the reversible thermosensitive recording material and its half-facing surface (back surface). The results are shown in the “surface resistance value” column of Table 2.

[Sheets between sheets]
The reversible thermosensitive recording materials of Examples 17 to 21 and Comparative Examples 13 to 16 were cut into A4 size sheets, and the same using a printer (trade name: B-SX8R-TS15, manufactured by Toshiba TEC Corporation). Ten A4 sheets of reversible thermosensitive recording material were continuously erased and printed. Here, the erasure printing is one in which the reversible thermosensitive recording material is first erased and then processed in the order of printing, and the image is rewritten. Erasing is performed with a heat roll, and printing is performed with a thermal head of about 305 dpi. The conditions were an erasing temperature of 170 ° C. and a printing speed of 2 inches / second. The sheets on which erasure printing was completed were overlapped so that the printing surface (front side) and the opposite surface (back side) were in close contact with each other. After standing for 10 minutes, the superimposed sheets were continuously erased and printed again using the printer, and the sheet conveyance failure was evaluated. The process from erasure printing to evaluation was performed in an environment of 23 ° C. and 50% RH. The results are shown in the column “Sheet Conveyance” in Table 2. In Table 2, ○ indicates that there is no conveyance failure, Δ indicates that double feeding of two or more sheets out of 10 sheets occurs once, and x indicates that the double feeding occurs twice or more. .

[Repeat Print / Erase]
The reversible thermosensitive recording materials of Examples 17 to 21 and Comparative Examples 13 to 16 were cut into A4 size sheets, and erased and printed using a printer (trade name: B-SX8R-TS15, manufactured by Toshiba TEC Corporation). Went. The erasing temperature was 170 ° C., the printing speed was 2 inches / second, and erasing printing was repeated 30 times at intervals of 5 minutes on one sheet.

  The optical density of the printed part at the 30th time was measured with a reflection densitometer (trade name: RD-19, manufactured by GretagMacbeth). The results are shown in the “print density” column of Table 2. Further, the printed surface was observed to evaluate the presence or absence of printing defects due to adhesion of foreign matters such as dust. The results are shown in the “Printing Missing” column of Table 2.

[Printing ink fillability]
A printability tester (trade name “RI-1”, Ishikawajima) was printed on the reversible thermosensitive recording materials of Examples 17 to 21 and Comparative Examples 13 to 16 (front side) and the opposite side (back side). Ink fillability test was carried out using an industrial machine. The printing ink was offset UV ink (trade name “Best Cure Vector HD Process Black”, manufactured by T & K TOKA Corporation), and 5 ml of ink was used per test. The image after printing was cured by passing under an ultraviolet lamp with a lamp output of 80 W / cm at a conveyance speed of 10 m / min, and then the optical density was measured with a reflection densitometer (trade name “RD-19”, manufactured by Gretag Macbeth). Measured and evaluated to 4 levels. In the four-level classification, a density of 1.2 or higher was evaluated as ◎, 1.0 or higher and lower than 1.2 as ◯, 0.8 or higher and lower than 1.0 as Δ, and less than 0.8 as X. The higher the concentration, the better the ink deposition property, and the greater the effect of the present invention.

[Peel strength]
For the PET side having the reversible thermosensitive recording layers of the reversible thermosensitive recording materials of Examples 17 to 21 and Comparative Examples 13 to 16, a peel strength test was performed according to “JIS X 6305-1 5.3 Peel Strength”. went. The results are shown in the “Peel strength” column of Table 2.

As is clear from Tables 1 and 2, the reversible thermosensitive recording materials of Examples 1 to 16 and Examples 17 to 21 were prepared by adding a layer to which a halogen-free salt composed of a dicyanamide anion and an organic cation was added to the front side. The surface resistivity of the surface provided on any outermost layer of the back surface was less than 10 ¹¹ Ω / □, indicating a sufficient antistatic property. Also, the sheets were difficult to stick to each other and could be peeled off with a small force. Further, even when a layer to which a halogen-free salt composed of a dicyanamide anion and an organic cation was added was provided on the outermost layer of either the front side or the back side, printing was always possible at a high print density. Furthermore, the printing ink has good fillability, and the problem of achieving both antistatic properties and printability has been achieved.

  Further, as is apparent from Table 2, the reversible thermosensitive recording materials of Examples 17 to 21 have a reduced peel strength even when a halogen-free salt composed of a dicyanamide anion and an organic cation is added to the heat-fusible layer. The problem of achieving both antistatic properties and peel strength properties has also been achieved.

  The reversible thermosensitive recording material of the present invention is capable of forming and erasing images with a clear contrast, can hold images that are stable over time in the environment of daily life, and can be repeatedly formed and erased stably. In addition, it can be used as a reversible thermosensitive recording material that has few conveyance failures in the image forming apparatus due to charging, is excellent in visibility of the formed image, and has markedly improved printing ink inking properties and peeling after card molding.

Claims (2)

In a reversible thermosensitive recording material provided with a thermosensitive recording layer whose transparency or color tone reversibly changes by controlling thermal energy on a support, at least one of the surface on the same side as the reversible thermosensitive recording layer or the surface on the opposite side A dicyanamide anion represented by the following general formula (1) and a quaternary ammonium cation represented by the following general formula (2), a pyridinium cation represented by the following general formula (3), or A reversible thermosensitive recording material comprising at least one salt with an imidazolium cation represented by the following general formula (4).

(In General Formula (2), at least one group of R ₁ to R ₄ represents an aliphatic hydrocarbon group having 6 to 22 carbon atoms, and the remaining group is a hydroxyalkyl group having 1 to 3 carbon atoms, An aliphatic hydrocarbon group having 1 to 5 carbon atoms, an aryl group having 6 to 11 carbon atoms, or an arylalkyl group having 7 to 12 carbon atoms, and when there are a plurality of the remaining groups, they are the same as each other It may or may not be.)

(In General Formula (3), R ₅ represents an aliphatic hydrocarbon group having 1 to 22 carbon atoms, and R ₆ represents a hydrogen atom or an aliphatic hydrocarbon group having 1 to 8 carbon atoms.)

(In the general formula (4), R ₇ and R ₈ may be the same or different and each represents an aliphatic hydrocarbon group having 1 to 12 carbon atoms, and R ₉ is a hydrogen atom or an aliphatic hydrocarbon having 1 to 8 carbon atoms. Represents a hydrocarbon group.)   2. The reversible thermosensitive recording material according to claim 1, wherein the salt of the dicyanamide anion and the organic cation is a halogen-free organic salt that is liquid at room temperature.