JP6086025B2 - Thermosensitive recording medium and recording method thereof - Google Patents

Description

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

  A heat-sensitive recording material is known which uses a reaction between a dye precursor and a developer and causes both substances to react with each other by thermal energy to obtain a recorded image. Such a heat-sensitive recording material is relatively inexpensive, and since the recording device is compact and easy to maintain, it is used not only as a recording medium for facsimiles and printers but also in a wide range of fields.

  However, the performance and quality required with the expansion of applications are diversified. Examples thereof include high-density recording, image stabilization, and a thermal recording medium having a color tone of a color image. In particular, for a thermal recording material having a metal-like color image that has a possibility of widening the application range, a pigment in which at least one of titanium oxide and iron oxide is coated on the surface of natural mica on the thermal recording layer. Providing a coating layer containing (see Patent Document 1), providing a layer containing an inorganic pearl pigment on a heat-sensitive recording layer (see Patent Document 2), etc. have been proposed. At present, satisfactory results are not always obtained in the storage stability of the color image.

Japanese Patent Laid-Open No. 2-206585 Japanese Patent Laid-Open No. 6-297846

  The present invention provides a heat-sensitive recording material using a color development reaction between a dye precursor and a developer, and a heat-sensitive recording material in which a color-developed image has a metallic luster and has a brilliant golden metallic tone. Main purpose.

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

  Item 1: In a heat-sensitive recording material comprising a heat-sensitive recording layer containing a dye precursor and a developer on a support, the support has a metallic luster, and the dye precursor develops a yellow color. A heat-sensitive recording material which is a dye precursor.

Item 2: A dynamic color density obtained by printing the thermal recording medium with a thermal head at an applied energy of 0.97 mJ / dot is 1.00 or more, and the thermal recording medium is a hot plate of 40 to 220 ° C. Item 2. The thermal recording material according to Item 1, wherein the static color development start temperature at which the color density obtained by contact at 9.8 × 10 ⁴ Pa for 5 seconds is 0.2 is 50 ° C. or higher.

Item 3: The heat-sensitive recording material according to Item 1 or 2, wherein the content of the dye precursor that develops the yellow color tone is 0.7 g / m ² or more.

  Item 4: The dye precursor that develops a yellow color tone is a dye precursor having a pyridine skeleton in a molecular structure represented by the following general formula (1): Thermal recording material.

（式中、Ｒ^１及びＲ^２は水素原子もしくは炭素数１〜８のアルコキシ基を表し、同一であっても、異なっていてもよい。Ｒ^３は炭素数１〜４のアルキル基を表す。）

(Wherein, R ¹ and R ² represent a hydrogen atom or an alkoxy group having 1 to 8 carbon atoms, it may be the same, good .R ³ be different represents an alkyl group having 1 to 4 carbon atoms. )

  Item 5: The heat-sensitive recording material according to any one of Items 1 to 4, wherein the support is obtained by imparting a metallic luster to the surface of a substrate having no metallic luster.

  Item 6: The method for recording a heat-sensitive recording material according to any one of Items 1 to 5, wherein a color image of a golden metal tone is recorded by heating with a thermal head at an applied energy that is equal to or higher than a static color development start temperature. And recording in a silver metal tone with an applied energy of less than 1.00.

  The heat-sensitive recording material of the present invention is a variable with excellent design as an alternative to a special color printing product that has been centered in the printing field so far, with a color-developed image that has a metallic luster and a vivid golden metallic tone. Can record information. In addition, the color density is high, and the color image has excellent storage stability and light resistance.

  The present invention relates to a thermosensitive recording medium comprising a thermosensitive recording layer containing a dye precursor and a developer on a support, wherein the support has a metallic luster and the dye precursor develops a yellow color tone. It is a thermal recording material characterized by being a precursor.

  The support in this invention should just have a metallic luster on at least one side, and there is no special limitation in a kind, a shape, a dimension, etc. For example, a metal plate, a metal foil, a metal film or the like itself having a metallic luster, fine paper (acid paper, neutral paper), medium paper, coated paper, art paper, cast coated paper, glassine paper, A support provided with a metallic luster on a substrate having no metallic luster, such as paperboard, cardboard, resin-laminated paper, polyolefin synthetic paper, synthetic fiber paper, non-woven fabric, and synthetic resin film, can be appropriately selected and used. The substrate may be transparent, translucent, or opaque. Among these, since a specular gloss can be obtained visually, a support provided with a metallic gloss on a film or synthetic paper is preferable.

  As a method for imparting a metallic luster to the surface of the substrate, there are a method of plating, a method of bonding a metal foil such as an aluminum foil, and a method of bonding a paper or film having a metal vapor-deposited layer. Furthermore, there is a method in which a metal vapor deposition film such as aluminum or silver is directly provided on the substrate. In this case, a smooth resin layer is preliminarily provided on the surface of the substrate, and a direct vapor deposition method in which a metal vapor is deposited thereon to form a metal layer, or a metal vapor deposition layer previously provided on the film is bonded via an adhesive. There is a method in which the film is peeled off and transferred to a substrate. There is also a method of providing a metallic luster layer by printing or coating on a substrate. In this case, it is possible to obtain a metallic glossy surface using a metal ink obtained by mixing a metal powder such as aluminum powder or an aluminum paste in which aluminum powder is dispersed in a solvent with a vehicle. It is also possible to use not mica powder, but mica or ink using inorganic pearl pigment such as pigment obtained by coating mica with titanium oxide.

  The heat-sensitive recording layer in the present invention is formed on a support and covers part or all of the metallic luster of the support when viewed from the recording surface side. The heat-sensitive recording layer may be formed on the side having the metallic luster of the support, and for example, if it is a support having a metallic luster that can be visually confirmed through the substrate like a transparent substrate, You may form in the other side of the surface which has a metallic luster of a support body. Although an undercoat layer can be provided between the support and the heat-sensitive recording layer, it is preferable that the undercoat layer does not mask the metallic luster of the support.

  In the heat-sensitive recording material of the present invention, the dye precursor in the heat-sensitive recording layer develops a yellowish color tone, but since the colored image has a metallic luster when viewed from the recording surface side, the color tone of a vivid golden metal tone is visible. Can be presented. In the present invention, the dye precursor present in the form of fine particles in the heat-sensitive recording layer and the developer that develops the color of the dye precursor by reacting with heating is once melted by the applied energy of a thermal head and solidified again. Thus, it is considered that the irregular reflection in the heat-sensitive recording layer is reduced and a golden metal tone can be obtained through the heat-sensitive recording layer. In the present invention, the heat-sensitive recording layer covers the metallic luster of the support, but since the color image exhibits a golden metal tone, the degree to which the thermo-sensitive recording layer conceals the metallic luster of the support is limited. However, it is not particularly limited, and it may be a mat-like plain paper like when viewed from the recording surface side, or may be such that the metallic luster can be visually confirmed through the heat-sensitive recording layer.

In the present invention, the dynamic color density obtained by printing the thermal recording material with a thermal head at an applied energy of 0.97 mJ / dot is 1.00 or more, and the thermal recording material is applied to a hot plate at 40 to 220 ° C. It is preferable that the static color development start temperature at which the color density obtained by contact at 8 × 10 ⁴ Pa for 5 seconds is 0.2 is 50 ° C. or higher. As a result, the load on the printer can be reduced, a color tone-temperature curve having contrast can be obtained, and the color density can be increased to obtain a sufficient golden metal tone. By setting the dynamic color density to 1.00, it reaches a level that can be evaluated as being sufficient visually, but is more preferably 1.30 or more, and even more preferably 1.60 or more. The upper limit of the dynamic color density is not particularly limited, but if it exceeds 2.0, the color developability is saturated. On the other hand, the static color development start temperature is more preferably 60 ° C. or higher. The upper limit of the static color development start temperature is not particularly limited, but is preferably 90 ° C. or lower, more preferably 80 ° C. or lower, and still more preferably 70 ° C. or lower in order to reduce the load on the printer. Here, the color density indicates the Y (yellow) density. In order to adjust the desired color density, for example, the method of adjusting the content of the dye precursor or adjusting the form of the dye precursor can be used.

The content of the dye precursor that develops a yellow color tone is preferably 0.7 g / m ² or more in terms of the dry weight in the heat-sensitive recording layer. More preferably, it is 1.0 g / m < ² > or more, More preferably, it is 1.5 g / m < ² > or more. Thereby, it is possible to increase the color density and obtain a clearer golden metal tone. The upper limit of the content is not particularly limited, greater than 6 g / m ² and color developing property from saturating, it is preferable that the 6 g / m ² or less.

  Specific examples of the dye precursor that develops a yellow color tone include, for example, 4- [2- (2-butoxyphenyl) -6-phenyl-4-pyridinyl] -N, N-dimethylbenzenamine, 4- [ 2- (2-pentyloxyphenyl) -6-phenyl-4-pyridinyl] -N, N-dimethylbenzenamine, 4- [2- (2-hexyloxyphenyl) -6-phenyl-4-pyridinyl] -N , N-dimethylbenzenamine, 4- [2- (2-octyloxyphenyl) -6-phenyl-4-pyridinyl] -N, N-dimethylbenzenamine, 4- (2,6-diphenyl-4-pyridinyl) -N, N-dimethylbenzenamine, 4- [2,6-bis (2-butoxyphenyl) -4-pyridinyl] -N, N-dimethylbenzenamine, 4- [2,6-bis ( -Pentyloxyphenyl) -4-pyridinyl] -N, N-dimethylbenzenamine, 4- [2,6-bis (2-hexyloxyphenyl) -4-pyridinyl] -N, N-dimethylbenzenamine, and 4 Examples include dye precursors having a pyridine skeleton in the molecular structure such as-[2,6-bis (2-octyloxyphenyl) -4-pyridinyl] -N, N-dimethylbenzenamine. Examples of the dye precursor that develops a yellow color without a pyridine skeleton include 3,6-dimethoxyfluorane, 1- (4-n-dodecyloxy-3-methoxyphenyl) -2- (2 -Quinolyl) ethylene, 2,2-bis (4- (2- (4-diethylaminophenyl) quinazolyl) oxyphenyl) propane, 1- (2-quinolyl) -2- (3-methoxy-4-dodecyloxyphenyl) Examples include ethene and 4-chloro-N- (4- (N- (4-methylbenzyl) -N-methylamino) benzylidene) aniline.

  The dye precursor that develops a yellow color tone in the present invention preferably has excellent storability of a color image. If the color image is faded, the reason for the crystallization of the components in the heat-sensitive recording layer is not clear, but the metal tone may be deteriorated more than the appearance of the yellow color tone. In the present invention, a dye precursor having a pyridine skeleton in the molecular structure represented by the following general formula (1) is preferable as a dye precursor that develops a yellowish color tone from the viewpoint of improving the storage stability of a color image.

（式中、Ｒ^１及びＲ^２は水素原子もしくは炭素数１〜８のアルコキシ基を表し、同一であっても、異なっていてもよい。Ｒ^３は炭素数１〜４のアルキル基を表す。）

(Wherein, R ¹ and R ² represent a hydrogen atom or an alkoxy group having 1 to 8 carbon atoms, it may be the same, good .R ³ be different represents an alkyl group having 1 to 4 carbon atoms. )

Further, from the viewpoint of further increasing the color density, it is more preferable that R ¹ and R ² in the general formula (1) are excluded from being simultaneously hydrogen atoms. In the general formula (1), R ¹ and R ² are a hydrogen atom or an alkoxy group having 1 to 8 carbon atoms which may be branched, and may be the same or different, and R ³ has 1 to 4 carbon atoms. In this formula, at least R ¹ and R ² are preferable because a linear saturated hydrocarbon group can be easily introduced industrially.

In the present invention, in the general formula (1), it is preferable that any ^one of R ¹ and R ² is an alkoxy group having 4 to 8 carbon atoms because the effects of the present invention can be exhibited without any regret. Furthermore, from the viewpoint of further increasing the color density, it is preferable that either R ¹ or R ² represents a hydrogen atom.

  In the present invention, 4- [2- (2-butoxyphenyl) -6-phenyl-4-pyridinyl is one of the dye precursors that develop a yellow color tone from the viewpoint of further improving the storage stability of the color image. ] -N, N-dimethylbenzenamine, 4- [2- (2-pentyloxyphenyl) -6-phenyl-4-pyridinyl] -N, N-dimethylbenzenamine, and 4- [2- (2-hexyl) It is preferable to use one selected from the group consisting of (oxyphenyl) -6-phenyl-4-pyridinyl] -N, N-dimethylbenzenamine.

  In the present invention, the form of the dye precursor contained in the heat-sensitive recording layer is not particularly limited, and may be contained in the heat-sensitive recording layer in the form of solid dispersed fine particles. May be contained in the heat-sensitive recording layer in a form in which composite fine particles containing a polymer compound such as a photosensitive resin are formed.

  When the dye precursor is used in the form of solid dispersed fine particles, for example, water is used as a dispersion medium and pulverized by various wet pulverizers such as a sand mill, an attritor, a ball mill, and a cobo mill to obtain a dispersion. In addition to water-soluble polymer compounds such as polyacrylamide, polyvinylpyrrolidone, polyvinyl alcohol, modified polyvinyl alcohols such as sulfone-modified polyvinyl alcohol, methylcellulose, carboxymethylcellulose, styrene-maleic anhydride copolymer salts and derivatives thereof, are necessary. Depending on the above, it can be dispersed in a dispersion medium in the presence of a surfactant, an antifoaming agent or the like to form a dispersion. What is necessary is just to prepare the coating liquid for forming a thermosensitive recording layer using this dispersion liquid. In addition, after dissolving the dye precursor in an organic solvent, this solution is emulsified and dispersed in water using the above water-soluble polymer compound as a stabilizer, and then the organic solvent is evaporated from the emulsion to make the dye precursor into solid dispersed fine particles. Can also be used. In any case, the volume average particle diameter of the solid dispersion fine particles of the dye precursor used in the form of the solid dispersion fine particles is preferably about 0.2 to 3.0 μm, more preferably in order to obtain appropriate recording sensitivity. Is about 0.3 to 1.0 μm.

As a form in which composite fine particles containing a dye precursor and a hydrophobic resin are formed,
(1) A form in which one or more dye precursors are microencapsulated using a hydrophobic resin as a wall film,
(2) A form in which one or more dye precursors are contained in a base material made of a hydrophobic resin obtained from a polyvalent isocyanate or the like,
(3) A form in which a compound having an unsaturated carbon bond is polymerized on the surface of one or more dye precursor fine particles,
Etc. For example, a method described in JP-A-60-244594 can be cited as a method for producing the particles having the form (1). Examples of the method for producing particles having the form (2) include the method described in JP-A-9-263057. Examples of the method for producing the particles having the form (3) include the method described in JP-A No. 2000-158822.

  The hydrophobic resin forming the composite fine particles is not particularly limited, and examples thereof include urea resins, urethane resins, urea-urethane resins, styrene resins, acrylic resins, and the like. Among these, since the urea-based resin and the urea-urethane resin are excellent in heat-resistant surface fogging property, a form in which the second dye precursor forms composite fine particles with the polyurea or polyurea-polyurethane resin is preferable.

  The polyvalent isocyanate compound used for the production of the composite fine particles is a compound that forms polyurea or polyurea-polyurethane by reacting with water, and may be a polyvalent isocyanate compound alone or a polyvalent isocyanate. It may be a compound, a polyol that reacts with this, a mixture of polyamines, or an adduct of a polyvalent isocyanate compound and a polyol, a multimer such as a biuret or isocyanurate of a polyvalent isocyanate compound. A dye precursor is dissolved in these polyvalent isocyanate compounds, and this solution is dissolved in an aqueous medium containing a protective colloid substance such as polyvinyl alcohol, and the volume average particle diameter is preferably 0.2 to 3.0 μm. The polyisocyanate compound is obtained by emulsifying and dispersing to a degree, more preferably about 0.2 to 1.5 μm, and further, if necessary, mixing a reactive substance such as polyamine and then heating the emulsified dispersion. Polymerize. As a result, the polyvalent isocyanate compound can be polymerized to form composite fine particles containing the dye precursor.

  The dye precursor contained in the composite fine particles is highly separable from the outside, and the color former is very good storage stability, especially oils and plasticizers, compared to the color former colored in the state of solid dispersed fine particles. It is excellent in resistance to. The reason for this is not necessarily clear, but it is considered that the color former and the polymer substance (matrix) have some interaction and are stabilized.

  The appearance of the composite fine particles used in the present invention is almost spherical when observed with an electron microscope, or is somewhat erythrocytic. In cross-sectional observation with an electron microscope, the shape is an internal body, a porous body, or a hollow body. The volume average particle diameter is preferably about 0.2 to 1.5 μm in order to obtain appropriate recording sensitivity. By setting the thickness to 0.2 μm or more, it is desirable from the viewpoint of improving the storage stability of the color image with respect to oil, plasticizer and the like.

  The composite fine particles used in the present invention include, in addition to the dye precursor, a UV absorber, an antioxidant, a release agent, which will be described later, and a sensitizer known as a heat-sensitive recording material, if necessary. May be added.

  The forms (1) and (2) of these composite fine particles are superior in the transparency of the heat-sensitive recording layer as compared with the case where the dye precursor is used in the form of solid dispersed fine particles. In the present invention, by providing a heat-sensitive recording layer having high transparency, it is possible to obtain a heat-sensitive recording material in which the background portion exhibits a silver metal tone and the color image exhibits a gold metal tone through the heat-sensitive recording layer.

  Further, in the present invention, by utilizing the dynamic color development characteristics and the static color development characteristics, for example, by providing a heat-sensitive recording layer so as to conceal the metallic luster of the support using an aluminum-deposited support, It is also possible to record both a color image and a silver metal image. As a preferable recording method in this case, for example, by heating with a thermal head of a printer, a gold metal-tone color image is recorded with an applied energy that is equal to or higher than the static color development start temperature, and an applied energy at which the dynamic color density is less than 1.00 Can record in silver metal tone. When the temperature is higher than the static color development temperature, sufficient applied energy is given to exhibit a gold color, and when the dynamic color density is less than 1.00, it is insufficient to exhibit a gold color. A part of the developer can be melted to develop the metallic luster of the support and can exhibit a silver color.

  The content ratio of the dye precursor is preferably about 5 to 30% by mass, more preferably about 7 to 30% by mass, and still more preferably about 7 to 25% by mass in the total solid content of each thermosensitive recording layer. By setting the content to 5% by mass or more, the color density can be improved. Heat resistance can be improved by setting it as 30 mass% or less.

  The developer contained in the heat-sensitive recording layer in the present invention is selected from those having the property of being liquefied or dissolved by an increase in temperature and having the property of causing color development upon contact with the dye precursor. Specific examples include organic acidic substances such as phenol compounds, aromatic carboxylic acids, and polyvalent metal salts of these compounds.

  The developer usually exists in the form of composite fine particles, microcapsules, and solid dispersed fine particles. The content of the developer is preferably about 30 to 1500 parts by weight, more preferably about 50 to 1000 parts by weight, and still more preferably 100 to 600 parts per 100 parts by weight of the total dye precursor in each thermosensitive recording layer. About 200 parts by mass, particularly preferably about 140 to 600 parts by mass, and most preferably about 200 to 500 parts by mass. The composite fine particles can be prepared by a method similar to the method of preparing the composite fine particles containing the dye precursor.

  As typical developers, for example, 4-tert-butylphenol, 4-acetylphenol, 4-tert-octylphenol, 4,4′-sec-butylidene diphenol, 4-phenylphenol, 4,4′-dihydroxy Diphenylmethane, 4,4′-isopropylidene diphenol, 4,4′-dihydroxydiphenyl ether, 4,4′-cyclohexylidene diphenol, 1,1-bis (4-hydroxyphenyl) ethane, 1,1-bis (4 -Hydroxyphenyl) -1-phenylethane, 4,4'-dihydroxydiphenyl sulfide, 4,4'-thiobis (3-methyl-6-tert-butylphenol), 4,4'-dihydroxydiphenylsulfone, 2,4 ' -Dihydroxydiphenylsulfone, 4-hydroxy -4'-isopropoxydiphenylsulfone, 4-hydroxy-4'-n-propoxydiphenylsulfone, 4-hydroxy-4'-allyloxydiphenylsulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, 4,4 '-Bis [(4-methyl-3-phenoxycarbonylaminophenyl) ureido] diphenylsulfone, 4- [4'-(1'-methylethyloxy) phenyl] sulfonylphenol, N- (p-toluenesulfonyl) -N '-(3-p-toluenesulfonyloxyphenyl) urea, Np-tolylsulfonyl-p-butoxycarbonylphenylurea, N- (p-toluenesulfonyl) -N'-phenylurea, 4,4'-bis ( And compounds such as 3-tosylureido) diphenylmethane .

  Further, in the present invention, compounds that can be used as a developer include 4-hydroxybenzophenone, dimethyl 4-hydroxyphthalate, methyl 4-hydroxybenzoate, propyl 4-hydroxybenzoate, and 4-hydroxybenzoic acid-sec-butyl. Phenyl compounds such as phenyl 4-hydroxybenzoate, benzyl 4-hydroxybenzoate, tolyl 4-hydroxybenzoate, chlorophenyl 4-hydroxybenzoate, 4,4′-dihydroxydiphenyl ether, or benzoic acid, p-tert-butyl Benzoic acid, trichlorobenzoic acid, terephthalic acid, salicylic acid, 3-tert-butylsalicylic acid, 3-isopropylsalicylic acid, 3-benzylsalicylic acid, 3,5- (α-methylbenzyl) salicylic acid, 3,5-di-tert-butylsali Aromatic carboxylic acids such as Le acid, and the phenolic compounds, aromatic carboxylic acid and, for example, zinc, magnesium, aluminum, organic acidic substances of salts with polyvalent metals such as calcium and the like.

  Among these developers, 4-hydroxy-4′-isopropoxydiphenylsulfone, 4-hydroxy-4′-n-propoxydiphenylsulfone, 4-hydroxy-4′-allyloxydiphenylsulfone, bis (3-allyl -4-hydroxyphenyl) sulfone, 4,4'-bis [(4-methyl-3-phenoxycarbonylaminophenyl) ureido] diphenylsulfone, Np-tolylsulfonyl-N'-p-butoxycarbonylphenylurea, N -(P-toluenesulfonyl) -N '-(3-p-toluenesulfonyloxyphenyl) urea, N- (p-toluenesulfonyl) -N'-phenylurea, 4,4'-bis (3-tosylureido) diphenylmethane At least one selected from the group consisting of As a result, a brighter yellow color tone can be obtained, and the effects of the present invention can be exhibited without regret. Furthermore, 4-hydroxy-4′-isopropoxydiphenylsulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, N- (p-toluenesulfonyl) -N ′-(3-p-toluenesulfonyloxyphenyl) urea 4,4′-bis (3-tosylureido) diphenylmethane, N- (p-toluenesulfonyl) -N′-phenylurea, Np-tolylsulfonyl-N′-p-butoxycarbonylphenylurea Species are preferred.

  In the present invention, a preservability improving agent can be further contained in the heat-sensitive recording layer mainly in order to further improve the preservability of the color image. Examples of such preservability improvers include 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, 1,1,3-tris (2-methyl-4-hydroxy-). 5-tert-butylphenyl) butane, 1,1-bis (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 4,4 ′-[1,4-phenylenebis (1-methylethylidene) ] Phenols such as bisphenol and 4,4 '-[1,3-phenylenebis (1-methylethylidene)] bisphenol, 4-benzyloxyphenyl-4'-(2-methyl-2,3-epoxypropyloxy) ) Phenylsulfone, 4- (2-methyl-1,2-epoxyethyl) diphenylsulfone, and 4- (2-ethyl-1,2-epoxyethyl) ) At least one selected from epoxy compounds such as diphenylsulfone and isocyanuric acid compounds such as 1,3,5-tris (2,6-dimethylbenzyl-3-hydroxy-4-tert-butyl) isocyanuric acid is used. be able to. Of course, the storage stability improving agent is not limited to these, and two or more kinds of compounds may be used in combination as required.

  In the present invention, a sensitizer can be further contained in the heat-sensitive recording layer in order to improve the recording sensitivity. As the sensitizer, a compound conventionally known as a sensitizer for a thermal recording material can be used. For example, parabenzylbiphenyl, dibenzyl terephthalate, phenyl 1-hydroxy-2-naphthoate, dioxalate Benzyl ester, di-o-chlorobenzyl adipate, 1,2-diphenoxyethane, 1,2-di (3-methylphenoxy) ethane, di-p-methylbenzyl oxalate, di-p-chlorooxalate Benzyl ester, 2-naphthylbenzyl ether, diphenylsulfone, 1,2-diphenoxymethylbenzene, 1,2-bis (3,4-dimethylphenyl) ethane, 1,3-bis (2-naphthoxy) propane, metater Phenyl, diphenyl, benzophenone and the like can be mentioned.

  Auxiliary agents such as developers, preservatives and sensitizers used in the thermosensitive coloring layer are dispersed in water in the same manner as when the dye precursor is used in the form of solid dispersed fine particles. What is necessary is just to mix with this in the case of preparation of a coating liquid. Moreover, these adjuvants can be dissolved in a solvent and emulsified in water using a water-soluble polymer compound as an emulsifier. Further, the preservability improver and the sensitizer may be contained in the composite fine particles containing the dye precursor.

  In order to improve the whiteness of the heat-sensitive recording layer and improve the uniformity of the image, a fine pigment having a high whiteness and an average particle diameter of 10 μm or less can be contained in the heat-sensitive recording layer. For example, calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcined clay, silica, diatomaceous earth, synthetic aluminum silicate, zinc oxide, titanium oxide, aluminum hydroxide, barium sulfate, surface treated inorganic pigments such as calcium carbonate and silica In addition, organic pigments such as urea-formalin resin, styrene-methacrylic acid copolymer resin, and polystyrene resin can be used.

  As other component materials constituting the heat-sensitive recording layer, a binder is used, and if necessary, a crosslinking agent, waxes, metal soaps, colored dyes, colored pigments, fluorescent dyes and the like can be used. Examples of the binder include polyvinyl alcohol and derivatives thereof, starch and derivatives thereof, cellulose derivatives such as hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, methylcellulose, and ethylcellulose, polyacrylic acid soda, polyvinylpyrrolidone, and acrylamide-acrylic acid ester copolymer. Water-soluble polymer materials such as acrylamide-acrylic acid ester-methacrylic acid ester copolymer, styrene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, casein, gelatin and derivatives thereof, and Polyvinyl acetate, polyurethane, polyacrylic acid, polyacrylic ester, vinyl chloride-vinyl acetate copolymer, polybutyl methacrylate, ethylene-vinyl acetate Butadiene copolymer, styrene - - emulsion and styrene polymers such as butadiene - can be given latex water-insoluble polymer such as an acrylic copolymer.

  Examples of the cross-linking agent include aldehyde compounds such as glyoxal, polyamine compounds such as polyethyleneimine, epoxy compounds, polyamide resins, melamine resins, glyoxylate, dimethylol urea compounds, aziridine compounds, blocked isocyanate compounds, and peroxides. Inorganic compounds such as ammonium sulfate, ferric chloride, magnesium chloride, sodium tetraborate, and potassium tetraborate, or boric acid, boric acid triester, boron-based polymer, hydrazide compound, glyoxylate, and the like can be given. These may be used individually by 1 type and may be used in combination of 2 or more type. The amount of the crosslinking agent used is preferably in the range of about 1 to 10 parts by mass with respect to 100 parts by mass of the total solid content of the thermosensitive recording layer. Thereby, the water resistance of the thermosensitive recording layer can be improved.

  Examples of the wax include waxes such as paraffin wax, carnauba wax, microcrystalline wax, polyolefin wax, and polyethylene wax, and higher fatty acid amides such as stearic acid amide and ethylenebisstearic acid amide, higher fatty acid esters, and derivatives thereof. Can be mentioned.

  Examples of the metal soap include higher fatty acid polyvalent metal salts such as zinc stearate, aluminum stearate, calcium stearate, and zinc oleate. Further, if necessary, various auxiliary agents such as an oil repellent, an antifoaming agent and a viscosity modifier can be further added to the heat-sensitive recording layer as long as the effects of the present invention are not impaired.

  Furthermore, the light resistance can be greatly improved by incorporating microcapsules enclosing an ultraviolet absorber or solid dispersed fine particles of the ultraviolet absorber in the heat-sensitive recording layer.

  Specific examples of the ultraviolet absorber include salicylic acid-based ultraviolet absorbers such as phenyl salicylate, p-tert-butylphenyl salicylate, p-octylphenyl salicylate, 2,4-dihydroxybenzophenone, 2-hydroxy-4-octyloxy Benzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, 2- Examples thereof include benzophenone-based ultraviolet absorbers such as hydroxy-4-methoxy-5sulfobenzophenone.

  Furthermore, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-5′-tert-butylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) benzotriazole, 2- (2′-hydroxy-3′-tert-butyl-5′-methylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-3) ', 5'-di-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3', 5'-di-tert-amylphenyl) benzotriazole, 2- [2'-hydroxy -3 ′-(3 ″, 4 ″, 5 ″, 6 ″ -tetrahydrophthalimido-methyl) -5′-methylphenyl] benzotriazole, 2- (2 ′ Hydroxy-5′-tert-octylphenyl) benzotriazole, 2- [2′-hydroxy-3 ′, 5′-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (2′- Hydroxy-3'-dodecyl-5'-methylphenyl) benzotriazole, 2- [2'-hydroxy-4 '-(2 "-ethylhexyl) oxyphenyl] benzotriazole, polyethylene glycol (molecular weight about 300) and methyl-3 -[3-tert-butyl-5- (2H-benzotriazol-2-yl) -4-hydroxyphenyl] benzoic acid UV absorbers such as condensates with propionate, 2'-ethylhexyl-2-cyano- 3,3-diphenyl acrylate, ethyl-2-cyano-3,3-diphenyl acrylate It may be mentioned ultraviolet absorbent cyanoacrylate such bets, and the like. Of course, not limited thereto, may be used in combination of two or more depending also required.

  Among these ultraviolet absorbers, benzotriazole-based ultraviolet absorbers are preferable, and in particular, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole and 2- (2′-hydroxy-3′-tert-butyl-5). -Methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3'-dodecyl-5'-methylphenyl) benzotriazole, 2- [2'-hydroxy-4 '-(2 "-ethylhexyl) A condensate of oxyphenyl] benzotriazole, polyethylene glycol (molecular weight about 300) and methyl-3- [3-tert-butyl-5- (2H-benzotriazol-2-yl) -4-hydroxyphenyl] propionate is In particular, it is more preferable because it exhibits a remarkable light resistance improvement effect.

  The addition amount of the microcapsules encapsulating the ultraviolet absorber or the solid dispersed fine particles of the ultraviolet absorber is not particularly limited, but is preferably about 5 to 70% by mass in the total solid amount of the heat-sensitive recording layer. Especially preferably, it adjusts to the range of about 15-50 mass%. Light resistance can be improved by setting it as 5 mass% or more. If it exceeds 70% by mass, the light resistance is saturated, so that it is preferably about 70% by mass or less from the viewpoint of improving the recording sensitivity. The light resistance can be improved more effectively when the microcapsules encapsulating the ultraviolet absorber or the solid dispersed fine particles of the ultraviolet absorber are contained in the protective layer described later rather than in the heat-sensitive recording layer. .

  The heat-sensitive recording layer in the present invention uses, for example, water as a dispersion medium, a specific dye precursor, a developer, if necessary, a preservability improver, a sensitizer and the like, or a dispersion in which they are separately dispersed, Using a coating solution for a heat-sensitive recording layer prepared by mixing pigments, binders, cross-linking agents and other auxiliaries as necessary, it is applied and dried on the support so as to cover the metallic luster of the support. It is formed.

  In the present invention, it is desirable to provide a protective layer containing a water-soluble polymer material and a pigment as used in conventionally known thermal recording media on the thermal recording layer. As the water-soluble polymer material and the pigment, materials exemplified in the above-mentioned heat-sensitive recording layer can be used. At this time, it is more desirable to add a crosslinking agent to impart water resistance to the protective layer.

  In the present invention, the light resistance can be greatly improved by incorporating the microcapsules encapsulating the ultraviolet absorber or the solid dispersed fine particles of the ultraviolet absorber in the protective layer. In particular, microcapsules having a wall film made of polyurethane-polyurea resin or aminoaldehyde resin are excellent in heat resistance, and are therefore added to the thermal recording layer or protective layer for the purpose of preventing sticking to the thermal head. In addition to the excellent accompanying effect of fulfilling the function of an inorganic pigment, the refractive index is lower than that of other wall membrane microcapsules and ordinary pigments, and the shape is spherical. Even if it is contained in a large amount, it is preferably used because it does not cause a decrease in density due to irregular reflection of light.

  Further, by including a pigment, it is possible to prevent the adhesion of the residue to the thermal head and the sticking. As the oil absorption amount of the pigment, it is preferable to use a pigment of 50 ml / 100 g or more. The pigment content is preferably an amount that does not decrease the color density, that is, 50% by mass or less of the total solid content of the protective layer.

The protective layer is a protective layer coating solution prepared by mixing, for example, water as a dispersion medium and mixing a binder, and if necessary, a crosslinking agent, a pigment, and other auxiliaries. to 15 g / ^{m 2,} more preferably about so that 0.5 to 8 g / ^{m 2} approximately, is formed by applying and drying a heat-sensitive recording layer.

  In the present invention, the thermal recording material can be printed with UV ink, flexographic ink, or the like. In this case, printing may be performed on a support, a heat-sensitive recording layer, a protective layer, or the like.

  In the present invention, in order to increase the added value of the heat-sensitive recording material, it can be further processed to obtain a heat-sensitive recording material having a higher function. For example, a pressure-sensitive adhesive paper, a re-humidified adhesive paper, or a delayed tack paper can be obtained by applying coating processing on the back surface with a pressure-sensitive adhesive, a re-humidified adhesive, a delayed tack type pressure-sensitive adhesive, or the like. In particular, the anti-counterfeit recording material of the present invention that has been subjected to adhesive processing is useful as a heat-sensitive label. In addition, by using the back surface, a function as a thermal transfer paper, an ink jet recording paper, a carbonless paper, an electrostatic recording paper, and a zeography paper can be added to form a recording paper capable of double-sided recording. Of course, a double-sided thermal recording material can also be used. Further, a back layer can be provided for suppressing permeation of oil and plasticizer from the back surface of the heat-sensitive recording material, and for curling control and antistatic.

  Examples of methods for forming each layer on the support include air knife method, blade method, gravure method, roll coater method, spray method, dipping method, bar method, curtain method, slot die method, slide die method, and extrusion method. Any of the known coating methods may be used.

  In the present invention, it is preferable that at least one layer formed on the support is a layer formed by a curtain coating method. Thereby, a layer having a uniform thickness can be formed, and the recording sensitivity can be increased, and the barrier property against oil, plasticizer, alcohol, etc. can be increased. The curtain coating method is a method in which the coating liquid is allowed to flow and fall freely, and is applied to the support in a non-contact manner, and known methods such as a slide curtain method, a couple curtain method, and a twin curtain method can be employed. There is no particular limitation. In the curtain coating method, a layer having a more uniform thickness can be formed by simultaneous multilayer coating. In simultaneous multi-layer coating, each coating solution is laminated and then applied, and then dried to form each layer. After applying a coating solution that forms the lower layer, the lower surface coating surface is wet without drying. In a state, you may apply | coat the coating liquid which forms an upper layer on a lower layer coating surface, and it may be made to dry and form each layer after that. In the present invention, an embodiment in which a heat-sensitive recording layer and a protective layer are simultaneously applied in multiple layers is preferable from the viewpoint of improving barrier properties.

  Smoothing the heat-sensitive recording surface using a known smoothing method such as a super calendar or a soft calendar has an effect of increasing the recording sensitivity. The heat-sensitive recording surface may be applied to either a metal roll or an elastic roll of the calendar.

  The present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. Unless otherwise specified, “part” and “%” indicate “part by mass” and “% by mass”, respectively. Moreover, the volume average particle diameter of the pigment mix | blended with a color developer, a dye precursor, and a protective layer was measured using laser diffraction type particle size distribution analyzer SALD-2200 (made by Shimadzu Corporation).

Example 1
-Preparation of Dye Precursor Dispersion (Liquid A) As a dye precursor that develops a yellow color tone, 4- [2- (2-octyloxyphenyl) -6-phenyl-4-pyridinyl] -N, N- 40 parts of dimethylbenzenamine, 40 parts of a 10% aqueous solution of polyvinyl alcohol (polymerization degree 500, saponification degree 88%), and 20 parts of water are mixed, and average particle size is measured using a vertical sand mill (made by Imex Corporation, sand grinder). The liquid A was obtained by pulverizing to a diameter of 0.7 μm.

-Preparation of developer dispersion (liquid B) 40 parts of 4-hydroxy-4'-isopropoxydiphenyl sulfone, 40 parts of a 10% aqueous solution of polyvinyl alcohol (polymerization degree 500, saponification degree 88%), and water 20 parts It mixed and grind | pulverized until the volume average particle diameter was set to 1.5 micrometers using the ultra visco mill, and B liquid was obtained.

Preparation of sensitizer dispersion (liquid C) 40 parts of 1,2-di (3-methylphenoxy) ethane, 40 parts of 10% aqueous solution of polyvinyl alcohol (polymerization degree 500, saponification degree 88%), and water 20 parts Were mixed using a vertical sand mill (Sand Grinder, manufactured by Imex Co., Ltd.) so that the average particle size was 1.0 μm to obtain liquid C.

-Preparation of coating solution for heat-sensitive recording layer 20 parts of liquid A, 5 parts of styrene-butadiene latex (trade name: L1571, manufactured by Asahi Kasei Co., Ltd., solid content concentration 48%), 10% aqueous solution of polyvinyl alcohol (trade name: POVAL (registered) Trademark) PVA-110 (manufactured by Kuraray Co., Ltd.) 25 parts, B part 23 parts, C part 11 parts, 5% surfactant aqueous solution (trade name: SN Wet OT-70, San Nopco) 2 parts, and water 17 parts The composition consisting of was mixed and stirred to obtain a thermal recording layer coating solution.

-Preparation of Kaolin Dispersion (Liquid D) Kaolin (trade name: UW-90 (registered trademark), manufactured by BASF) 80 parts, 40% aqueous solution of sodium polyacrylate (trade name: Aron T-50, Toagosei Co., Ltd.) 1 part) and 53 parts of water were mixed and pulverized using a sand mill until the volume average particle diameter became 1.6 μm to obtain a liquid D.

-Preparation of coating solution for protective layer D part 25 parts, acetoacetyl-modified polyvinyl alcohol (trade name: Gohsephimer (registered trademark) Z-200, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., degree of polymerization: about 1000, degree of saponification: about 98 mol%) 15% aqueous solution, paraffin wax (trade name: Hydrin P-7, manufactured by Chukyo Yushi Co., Ltd., solid content concentration 30%) 7.5 parts, 5% surfactant aqueous solution (trade name: SN wet) OT-70 (manufactured by San Nopco) 5 parts, glyoxal (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., solid content concentration 40%) 0.3 part, and 12.5 parts of water are mixed and stirred for coating for protective layer A liquid was obtained.

-Preparation of heat-sensitive recording material On the surface provided with an aluminum vapor-deposited layer of aluminum vapor-deposited paper (trade name: Almic T, manufactured by Toppan Label Co., Ltd., thickness 50 μm) as a support, for coating solution for heat-sensitive recording layer, for protective layer coating amount after coating liquid each drying coating amount after drying 5.5 g / ^{m 2} (amount 1.5 g ^/ m 2 of the dye precursor which develops color tone of yellow), 3.0g / ^{m 2} After applying and drying with a Mayer bar, a super calendar process was performed to obtain a heat-sensitive recording material.

Example 2
In preparing the liquid A of Example 1, 4- [2- (2-octyloxyphenyl) -6-phenyl-4-pyridinyl] -N, N-dimethylbenzenamine is used as a dye precursor that develops a yellowish color tone. Instead of 4- [2- (2-butoxyphenyl) -6-phenyl-4-pyridinyl] -N, N-dimethylbenzenamine, a thermosensitive recording material was obtained in the same manner as in Example 1. It was.

Example 3
In preparing the liquid A of Example 1, 4- [2- (2-octyloxyphenyl) -6-phenyl-4-pyridinyl] -N, N-dimethylbenzenamine is used as a dye precursor that develops a yellowish color tone. Instead of 1- (4-n-dodecyloxy-3-methoxyphenyl) -2- (2-quinolyl) ethylene, a thermosensitive recording material was obtained in the same manner as in Example 1.

Example 4
In the preparation of the liquid A of Example 1, 4- [2- (2-octyloxyphenyl) -6-phenyl-4-pyridinyl] -N, N-dimethylbenzenamine is used as a dye precursor that develops a yellowish color tone. Instead of 4- [2- (2-hexyloxyphenyl) -6-phenyl-4-pyridinyl] -N, N-dimethylbenzenamine, a thermosensitive recording medium was prepared in the same manner as in Example 1. Obtained.

Example 5
In the preparation of the liquid A of Example 1, 4- [2- (2-octyloxyphenyl) -6-phenyl-4-pyridinyl] -N, N-dimethylbenzenamine is used as a dye precursor that develops a yellowish color tone. Instead of 4- [2- (2-pentyloxyphenyl) -6-phenyl-4-pyridinyl] -N, N-dimethylbenzenamine, a thermosensitive recording medium was prepared in the same manner as in Example 1. Obtained.

Example 6
In the preparation of the liquid A of Example 1, 4- [2- (2-octyloxyphenyl) -6-phenyl-4-pyridinyl] -N, N-dimethylbenzenamine is used as a dye precursor that develops a yellowish color tone. Instead of 4- [2,6-bis (2-butoxyphenyl) -4-pyridinyl] -N, N-dimethylbenzenamine, a thermosensitive recording material was obtained in the same manner as in Example 1. It was.

Example 7
In the preparation of the liquid A of Example 1, 4- [2- (2-octyloxyphenyl) -6-phenyl-4-pyridinyl] -N, N-dimethylbenzenamine is used as a dye precursor that develops a yellowish color tone. Instead of 4- (2,6-diphenyl-4-pyridinyl) -N, N-dimethylbenzenamine, a thermosensitive recording material was obtained in the same manner as in Example 1.

Example 8
In the production of the thermal recording material of Example 1, the coating amount after drying of the thermal recording layer coating liquid was changed to 5.5 g / m ² , and 2.5 g / m ² (a dye precursor that develops a yellow color tone). A heat-sensitive recording material was obtained in the same manner as in Example 1 except that the content of the material was 0.7 g / m ² ).

Example 9
In the preparation of heat-sensitive recording material of Example 1, in place of the coating amount after drying of the heat-sensitive recording layer coating composition to 5.5 g / m ^2, the dye precursor which develops color tone of 4.0 g / m 2 ^(yellow A heat-sensitive recording material was obtained in the same manner as in Example 1 except that the content of the material was 1.1 g / m ² ).

Example 10
In the production of the thermosensitive recording material of Example 1, the coating amount after drying of the thermosensitive recording layer coating liquid was changed to 5.5 g / m ² , and 20.0 g / m ² (a dye precursor that develops a yellow color tone). A heat-sensitive recording material was obtained in the same manner as in Example 1 except that the content of the material was 5.6 g / m ² ).

Example 11
In the production of the heat-sensitive recording material of Example 1, Example 1 was used except that instead of the aluminum vapor-deposited paper, an aluminum vapor-deposited film (trade name: VM-PET, manufactured by Toray Industries, Inc., thickness 50 μm) was used. A heat-sensitive recording material was obtained in the same manner.

Comparative Example 1
In the production of the thermosensitive recording material of Example 1, instead of the aluminum vapor-deposited paper as the support, a synthetic paper having no metallic luster (trade name: FPG-80, manufactured by YUPO Corporation, thickness 80 μm) was used. Obtained a heat-sensitive recording material in the same manner as in Example 1.

Comparative Example 2
In preparing the liquid A of Example 1, 4- [2- (2-octyloxyphenyl) -6-phenyl-4-pyridinyl] -N, N-dimethylbenzenamine is used as a dye precursor that develops a yellowish color tone. Instead of using 3-di (n-butyl) amino-6-methyl-7-arininofluorane, which is a dye precursor that develops a blackish color tone, the heat sensitivity was the same as in Example 1. A record was obtained.

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

(Color tone)
Using a thermal recording simulator (trade name: TH-PMD, manufactured by Okura Electric Co., Ltd.), recording was performed under the condition of applied energy of 0.968 mJ / dot, and the apparent color tone of the recording portion was visually evaluated.

(Metallic luster)
Using a hot air dryer, a baked surface that was colored at a temperature of 120 ° C. in the dryer was created, and the baked surface was visually observed and evaluated according to the following criteria.
A: Strong metallic luster.
○: Metallic luster.
X: There is no metallic luster.

(Dynamic color density)
Using a thermal recording simulator (trade name: TH-PMD, manufactured by Okura Electric Co., Ltd.), recording was performed under the condition of applied energy of 0.968 mJ / dot, and an x-rite spectral densitometer (trade name: trade name: X-rite 528, manufactured by X-Rite Co., Ltd., using color measurement) was used to measure the Y concentration. In order to obtain a sufficient gold color, the color density is preferably 1.00 or more, more preferably 1.30 or more, and still more preferably 1.60 or more.

(Static color development start temperature)
Using a thermal inclination tester (manufactured by Toyo Seiki Co., Ltd.), color was developed every 10 ° C. under conditions of pressure 9.8 × 10 ⁴ Pa, contact time 5 seconds, and 40 to 220 ° C. The Y density is measured with an x-rite spectral densitometer (trade name: x-rite 528, manufactured by X-Rite, color measurement used), and linear interpolation is performed between temperatures at which the color density is 0.2. A temperature corresponding to a color density of 0.2 was determined. In order to obtain a sufficient gold color, the temperature at which the color density is 0.2 is preferably 50 ° C. or higher, and more preferably 60 ° C. or higher.

(Preservation of color image)
Using a thermal recording simulator (trade name: TH-PMD, manufactured by Okura Electric Co., Ltd.), recording was performed under the condition of applied energy of 0.968 mJ / dot, and using a thermal recording medium having a recording portion, 50 ° C., 80%. After the treatment for 24 hours in an RH environment, the Y density of the recording part is measured with an x-rite spectral densitometer (trade name: x-rite 528, manufactured by X-Rite, color measurement used), and the following formula Thus, the remaining ratio of the color density in the recording area was obtained. The remaining ratio of the color density is preferably 50% or more, more preferably 70% or more, still more preferably 80% or more, and particularly preferably 90% or more.
Residual rate of color density (%) = [(color density after treatment) / (color density before treatment)] × 100

(Light resistance of color images)
Using a thermal recording simulator (trade name: TH-PMD, manufactured by Okura Electric Co., Ltd.), recording was performed under the condition of applied energy of 0.968 mJ / dot, and a thermal recording body having a recording portion was 5000 lux under a fluorescent lamp. After 100 hours of irradiation treatment, the Y density of the recording part was measured with an x-rite spectral densitometer (trade name: x-rite 528, manufactured by X-Rite, color measurement used), and the storability of the above color image was measured. In the same manner as described above, the residual ratio of the color density in the recording area was obtained. The remaining ratio of the color density is preferably 50% or more, more preferably 70% or more, still more preferably 80% or more, and particularly preferably 90% or more.

(Chromaticity)
Using a thermal recording simulator (trade name: TH-PMD, manufactured by Okura Electric Co., Ltd.), recording was performed under the condition of applied energy of 0.968 mJ / dot, and an x-rite spectral densitometer (trade name: x-rite 528, X-Rite). The chromaticity b ^* value of the recording part was measured using a color measurement used by the company. In order to obtain a sufficient gold color, +50.0 or more is preferable.

  The heat-sensitive recording material of the present invention exhibits a vivid golden metal tone, because the metallic luster of the support gives a color image that looks different from the color tone of the dye precursor contained in the heat-sensitive recording layer. Can do. For this reason, the thermosensitive recording material of the present invention can record variable information utilizing the vivid golden metal color tone, for example, various tickets such as gold vouchers, coupons, receipts, labels, bags, sample books, price tags, In addition to packing tags, direct mails, message cards, displays such as advertisements and signboards, packaging and packaging materials, etc., it is suitably used for applications such as substitution of gold leaf.

Claims (6)

A thermosensitive recording medium comprising a thermosensitive recording layer containing a dye precursor and a developer on a support, wherein the support has a metallic luster, and the dye precursor develops a yellowish color tone. A heat-sensitive recording material, wherein the color-development image exhibits a golden metal tone. A dynamic color density obtained by printing the thermal recording medium with a thermal head at an applied energy of 0.97 mJ / dot is 1.00 or more, and the thermal recording medium is placed on a hot plate at 40 to 220 ° C. to 9.8. The thermosensitive recording material according to claim 1, wherein the static color development starting temperature at which the color density obtained by contact at × 10 ⁴ Pa for 5 seconds is 0.2 is 50 ° C. or more. The heat-sensitive recording material according to claim 1, wherein the content of the dye precursor that develops a yellow color tone is 0.7 g / m ² or more. The thermosensitive according to any one of claims 1 to 3, wherein the dye precursor that develops a yellowish color tone is a dye precursor having a pyridine skeleton in a molecular structure represented by the following general formula (1). Recorded body.

(Wherein, R ¹ and R ² represent a hydrogen atom or an alkoxy group having 1 to 8 carbon atoms, it may be the same, good .R ³ be different represents an alkyl group having 1 to 4 carbon atoms. )   The heat-sensitive recording material according to any one of claims 1 to 4, wherein the support has a metallic luster on the surface of a substrate having no metallic luster.   6. The method for recording a thermosensitive recording material according to claim 1, wherein a color image of a golden metal tone is recorded by heating with a thermal head with an applied energy that is equal to or higher than a static color development start temperature, and a dynamic color density is 1. A recording method for a thermal recording material, wherein recording is performed in a silver metal tone with an applied energy of less than 0.00.