JP4508106B2 - Thermal recording material - Google Patents

Description

  The present invention relates to a heat-sensitive recording material excellent in water resistance, print running property (head residue), and sensitivity.

In general, a heat-sensitive recording medium is usually a colorless or light-colored electron-donating leuco dye and an electron-accepting developer such as a phenolic compound, which are ground and dispersed in fine particles, and then mixed together. -, A coating liquid obtained by adding a filler, a sensitivity improver, a lubricant and other auxiliary agents to a support such as paper, synthetic paper, film, plastic, thermal head, Color is generated by an instantaneous chemical reaction by heating such as hot stamping, thermal pen, laser light, etc., and a recorded image is obtained. Thermal recording media are widely used in facsimiles, computer terminal printers, automatic ticket vending machines, measuring recorders, etc., and with the diversification of their uses, high levels of image stability and There is a need for stability in the blank section.

  However, since the electron-donating leuco dye and the electron-accepting developer contained in the heat-sensitive recording layer are easily dissolved in various solvents, this heat-sensitive recording material can be used for inks such as water-based ink pens and oil-based ink pens, adhesives, and the like. When touched, there is a problem that the white paper portion easily develops color or the color density decreases when chemicals such as a plasticizer adhere to the image. In order to eliminate such drawbacks, Patent Documents 1 and 2 disclose a technique in which a protective layer mainly composed of a pigment and a resin is provided on a heat-sensitive recording layer.

  Also, in recent years, the use of thermal recording media has been expanded to various tickets, receipts, labels, bank ATMs, gas and electric meter readings, and car tickets, etc. Severe characteristics that have not been a problem in the past have begun to be required for thermal recording media. For these applications, it is often used outdoors, and the quality performance of the protective layer that can withstand use in harsher environments than before, such as moisture and moisture such as rain, sunlight, and high temperatures in the car in midsummer. Is required.

  In particular, regarding water resistance, when a water-soluble polymer such as polyvinyl alcohol or starch is used for the protective layer, a technique using a crosslinking agent such as glyoxal as in Patent Document 3 and Patent Document 4 to impart water resistance Is disclosed. Non-Patent Document 1 discloses a technique in which polyamide epichlorohydrin and polyethyleneimine are used in combination as a crosslinking agent. Furthermore, Patent Document 5 discloses a technique for imparting water resistance by using a hydrophobic resin emulsion such as an acrylic emulsion for a protective layer, and Patent Document 6 discloses a carboxy-modified polyvinyl alcohol, an epichlorohydrin resin, and a melamine for the protective layer. A technique for containing a resin is disclosed.

Japanese Patent Laid-Open No. 48-30437 JP 48-31958 A Japanese Patent Laid-Open No. 8-230324 JP-A-9-164863 JP-A-1-196389 JP 2005-335295 A Hiroaki Yokoi New Polyvinyl Alcohol Water Resistance System 2005 Paper Pulp Technology Association Annual Conference Presentation

However, the effects of the thermal recording materials described in Patent Documents 1 to 4 and Non-Patent Document 1 are still insufficient. In addition, the thermal recording material described in Patent Document 5 can provide sufficient water resistance, but the heat resistance of the acrylic emulsion itself is insufficient, which may hinder printing runnability such as head scum and stick, Due to the low viscosity at high shear, there is a problem of operability such that a desired coating amount cannot be obtained. Furthermore, although the heat-sensitive recording material of Patent Document 6 has good water resistance, it has a problem that formaldehyde (carcinogenic substance) derived from melamine resin is generated, so that it is difficult to use melamine resin. It has become to.
Therefore, the present invention uses a melamine-based resin for a heat-sensitive recording material that has sufficient water resistance against moisture and moisture such as rain when used outdoors, and has excellent print running performance (head residue) and sensitivity. It is an issue to provide without doing.

We, the present inventors have assiduously studied a result, to solve the above problems, the heat-sensitive recording layer containing a colorless or pale colored electron donating leuco dye and electron accepting color developing agent is provided on a support, in heat-sensitive recording material comprising a protective layer are sequentially stacked, carboxy-modified polyvinyl alcohol resins, epichlorohydrin resins and Po Riamin / amide-based resin, which is a degree of polymerization 300 to 1200 on the protective layer It was achieved by forming a heat-sensitive recording material containing fat (excluding epichlorohydrin-based resin) and the heat-sensitive recording layer containing an epichlorohydrin-based resin . Hereinafter, in the present invention, the polyamine / amide resin does not include an epichlorohydrin resin.

According to the present invention, a heat-sensitive recording material having sufficient water resistance against moisture and moisture such as rain when used outdoors, and having excellent printing runnability (head residue) and sensitivity is obtained by using a melamine resin. It can be obtained without use.

In the protective layer of the heat-sensitive recording material of the present invention, the carboxyl group of the carboxy-modified polyvinyl alcohol and the amine or amide portion of the epichlorohydrin resin as a crosslinking agent cause a crosslinking reaction and develop primary water resistance. Then, since the port Riamin / amide resin hydrophilic moiety and carboxy-modified polyvinyl alcohol and epichlorohydrin-based resin The formed a hydrophilic crosslinking sites attract each other, the cross-linked site of the port Riamin / amide resin A state in which the hydrophobic group is encapsulated, that is, a hydrophilic cross-linked site is protected from water by the hydrophobic group, and secondary water resistance is exhibited. For this reason, it is estimated that water resistance stronger than the prior art is obtained.

Further, the hydrophilic sites of Po Riamin / A phagemid based resin is attracted to a hydroxyl group of the carboxy-modified polyvinyl alcohol, it becomes a state of being wrapped hydrophobic group of the carboxy-modified polyvinyl alcohol Gapo Riamin / amide resin in the outside, the cationic sites of the Po Riamin / amide resin are crosslinked reaction of one and the carboxyl group of the carboxy-modified polyvinyl alcohol is also believed to contribute to high water reduction is expressed.
In the present invention, when the degree of polymerization of the carboxy-modified polyvinyl alcohol is 300 to 1200, remarkable water resistance is exhibited. The reason is presumed as follows. It is considered that carboxy-modified polyvinyl alcohol having a polymerization degree of 300 to 1200 is an appropriately sized molecule and has an appropriate degree of freedom. For example, if the polymerization degree is large, carboxy-modified polyvinyl alcohol itself intermolecular forces, by hydrogen bonding, because the free carboxyl group or hydroxyl group is reduced, the reaction between the port Riamin / amide resin or epichlorohydrin resin It is thought that it is hard to happen. Meanwhile, since the small degree of polymerization resulting in wrapped carboxy-modified polyvinyl alcohol itself Po Riamin / amide resin or epichlorohydrin resin, it would not be able to express a synergistic effect of the.
In this way, by giving a higher hydrophobic effect to the reaction site between the resin used in the protective layer and the crosslinking agent, the binder in the coating layer is prevented from being eluted by moisture or moisture. Water resistance (blocking resistance, wet rub resistance) can be improved.

The protective layer of the thermosensitive recording medium of the present invention, it has a three-dimensional structure by crosslinking reaction of carboxy-modified polyvinyl alcohol and epichlorohydrin resin, cationic der Lupo Riami on / amide Since the resin based on the anionic pigment exhibits a dispersion effect, it is considered to be a porous layer as compared with the prior art. For this reason, since the melt of the material with low heat resistance in the coating layer generated under high temperature conditions is adsorbed in the voids in the protective layer, it has excellent print running properties (head residue resistance).

  The carboxy-modified polyvinyl alcohol having a polymerization degree of 300 to 1200 used in the present invention is a reaction product of polyvinyl alcohol and a polyvalent carboxylic acid such as fumaric acid, phthalic anhydride, mellitic anhydride, itaconic anhydride, or the like. An esterified product of the reaction product, and a saponified product of a copolymer of vinyl acetate and an ethylenically unsaturated dicarboxylic acid such as maleic acid, fumaric acid, itaconic acid, crotonic acid, acrylic acid or methacrylic acid are obtained. Specifically, for example, the production method exemplified in Example 1 or 4 of JP-A-53-91995 can be mentioned. The saponification degree of the carboxy-modified polyvinyl alcohol is desirably 72 mol% or more, and more desirably 72 to 97 mol%. In the present invention, image quality and sensitivity are improved by using carboxy-modified polyvinyl alcohol. This is because carboxy-modified polyvinyl alcohol has a low Hercules viscosity, that is, it has a high fluidity in a state where rotational force (shear) is applied, and it is easy to immobilize at a low share, so the coating liquid extends smoothly during coating. It is considered that this is because a coating layer that is solidified immediately after coating and is uniform and has no unevenness is formed.

As the crosslinking agent used in the present invention, a combination of epichlorohydrin resin and Po Riamin / amide resin. When each of them is used alone, sufficient water resistance cannot be obtained, resulting in problems such as blocking. The other common crosslinking agents, for example, or glyoxal and epichlorohydrin resin in combination Po Riamin / amide resin, it is impossible to obtain sufficient water resistance.

  Specific examples of the epichlorohydrin-based resin used in the present invention include polyamide epichlorohydrin resin, polyamine epichlorohydrin resin, and the like, and they can be used alone or in combination. Moreover, as an amine which exists in the principal chain of an epichlorohydrin-type resin, the thing from a primary to a quaternary can be used, and there is no restriction | limiting in particular. Further, the degree of cationization and molecular weight are preferably water cation resistance, so that the degree of cationization is 5 meq / g · Solid (measured value at pH 7) and the molecular weight is 500,000 or more. Specific examples include Sumire's Resin 650 (30) (manufactured by Sumitomo Chemical), Sumire's Resin 675A (manufactured by Sumitomo Chemical), Sumire's Resin 6615 (manufactured by Sumitomo Chemical), WS4002 (manufactured by Seiko PMC), WS4020. (Made by Starlight PMC), WS4024 (made by Starlight PMC), WS4046 (made by Starlight PMC), WS4010 (made by Starlight PMC), CP8970 (made by Starlight PMC), and the like.

In the present invention, as a crosslinking agent, it is necessary to use a epichlorohydrin resin and Po Riamin / amide resin. Po Riamin / amide resin this will generally be private, such as printability improving agent, such as polyamide urea resins, polyethyleneimine resins, polyalkylene polyamine resins, polyalkylene polyamide resins, polyamine polyurea resin, modified Examples include polyamine resins, modified polyamide resins, polyalkylene polyamine urea formalin resins, polyalkylene polyamine polyamide polyurea resins, and specific examples include Sumire Resin 302 (manufactured by Sumitomo Chemical Co., Ltd .: Polyamine Polyurea Resin), Sumire Resin 712. (Sumitomo Chemical Co., Ltd .: polyamine polyurea resin), Sumire Resin 703 (Sumitomo Chemical Co., Ltd .: polyamine polyurea resin), Sumire Resin 636 (Sumitomo Chemical Co., Ltd .: polyamine polyurea resin), Sumire Resin SPI -100 (residential Chemical Company: Modified Polyamine Resin), Sumire Resin SPI-102A (Sumitomo Chemical: Modified Polyamine Resin), Sumire Resin SPI-106N (Sumitomo Chemical: Modified Polyamide Resin), Sumire Resin SPI-203 ( 50) (manufactured by Sumitomo Chemical Co., Ltd.), Sumirez resin SPI-198 (manufactured by Sumitomo Chemical Co., Ltd.), printable A-700 (manufactured by Asahi Kasei Co., Ltd.), printable A-600 (manufactured by Asahi Kasei Co., Ltd.), PA 6500 (manufactured by Seiko PMC) : Polyalkylene polyamine urea formalin resin), PA6504 (manufactured by Seiko PMC: polyalkylene polyamine urea formalin resin), PA 6634 (manufactured by Seiko PMC: polyalkylene polyamine polyamide polyurea resin), PA 6638 (manufactured by Seiko PMC: polyalkylene polyamine) Polyamide polyurea resin), A 6640 (manufactured by Seiko PMC: polyalkylene polyamine polyamide polyurea resin), PA 6644 (manufactured by Seiko PMC: polyalkylene polyamine polyamide polyurea resin), PA 6646 (manufactured by Seiko PMC: polyalkylene polyamine polyamide polyurea resin), PA 6654 ( Starlight PMC: Polyalkylene polyamine polyamide polyurea resin), PA6702 (Starlight PMC: polyalkylene polyamine polyamide polyurea resin), PA6704 (Starlight PMC: polyalkylene polyamine polyamide polyurea resin), CP8994 (Starlight PMC) (Manufactured by: Polyethyleneimine resin) and the like, and are not particularly limited. Polyamide urea resin, polyalkylene polyamine resin, polyalkylene polyamide resin, polyamine Minpolyurea resin, modified polyamine resin, modified polyamide resin, polyalkylene polyamine urea formalin resin, and polyalkylene polyamine polyamide polyurea resin are desirable from the viewpoint of water resistance. Furthermore, it is desirable to use a polyamine resin (polyalkylene polyamine resin, polyamine polyurea resin, modified polyamine resin, polyalkylene polyamine urea formalin resin, polyalkylene polyamine polyamide polyurea resin) from the viewpoint of color development sensitivity.

The mixing ratio of the carboxy-modified polyvinyl alcohol resin and epichlorohydrin resin and Po Riamin / amide resin contained in the protective layer of the present invention (dry weight), in 1 part by weight Po Riamin / amide resin in contrast, 5 to 30 parts by weight carboxy-modified polyvinyl alcohol resin, the proportion of the epichlorohydrin-based resin is 1 to 15 parts by weight is desirable, and more preferably with respect to 1 part by weight of po Riamin / amide resin, carboxy-modified The polyvinyl alcohol resin is 10 to 20 parts by weight, and the epichlorohydrin resin is 1 to 5 parts by weight. The crosslinking reaction between the content of the epichlorohydrin resin and Po Riamin / amide resin is too small, no good water resistance becomes insufficient to obtain, if too great operating the viscosity increase or gelation of the coating liquid This is not preferable because it causes a problem of sex.

The pH of the protective layer coating solution is preferably 6.0 or higher. In particular, epichlorohydrin-based resins are alkali-curable, so that a good cross-linking reaction is performed within this range, and adjusting the pH below this range is not preferable because the cross-linking reaction is inhibited.
In the protective layer of the heat-sensitive recording material of the present invention, it is desirable to contain a pigment in order to improve sticking resistance and general printability such as offset printing. Examples of the pigment to be contained in the protective layer include silica, calcium carbonate, kaolin, calcined kaolin, diatomaceous earth, talc, titanium oxide, aluminum hydroxide and the like, and are not particularly limited. It is preferable to use aluminum hydroxide, kaolin, or silica. In particular, it is desirable to contain kaolin having an aspect ratio of 20 or more, more preferably 30 or more.

By using kaolin having an aspect ratio of 20 or more, the coverage of the thermosensitive recording layer is improved. For this reason, the storage stability of the image area and the blank paper area can be improved with a small coating amount, and a decrease in the thermal conductivity to the heat-sensitive recording layer can be suppressed, so that a good color development sensitivity and a recorded image can be obtained. it can. Moreover, the smoothness and glossiness of the coating layer surface are improved by containing kaolin having an aspect ratio of 20 or more. For this reason, target smoothness can be obtained by processing such as a low-pressure super calendar, and as a result, good color development sensitivity and recorded image can be obtained. However, when the aspect ratio is 100 or more, the protective layer becomes dense, which causes problems such as a decrease in ink fillability and ink drying in general printing, and a decrease in color development sensitivity. For this reason, the more preferable aspect-ratio of the kaolin contained in a protective layer in this invention is 20-100, More preferably, it is 30-75.

In addition, when the average diameter of the pigment having an aspect ratio of 20 or more contained in the protective layer is larger than 4 μm, the pigment is exposed on the surface of the coating layer, so that the surface smoothness, the recording image quality, the glossiness, Problems such as a decrease in gloss of the printed part and an increase in friction with the thermal head (head wear) occur. For this reason, it is desirable that the particle diameter of the pigment having an aspect ratio of 30 or more is 4 μm or less. Further, when the oil absorption amount of the pigment having an aspect ratio of 20 or more is 30 to 100 ml / 100 g, the ink inking property and the gloss of the printed part in general printing are improved. If the oil absorption amount is 30 ml / 100 g or less, the ink for general printing is difficult to be absorbed, which causes a problem in ink setting. If the oil absorption amount is 100 ml / 100 g or more, the ink for general printing is excessively absorbed. Therefore, a heat-sensitive recording material having a high print area gloss cannot be obtained. In the present invention, the aspect ratio of the pigment is an average value of “diameter / thickness” of 100 particles obtained by photographing powder with an electron microscope and randomly extracted, and the larger the aspect ratio value is. The flatness of the pigment is large.

  The content ratio (dry weight) of the carboxy-modified polyvinyl alcohol used in the present invention is preferably 10 to 500 parts by weight with respect to 100 parts by weight of the pigment, more preferably 20 to 250 parts with respect to 100 parts by weight of the pigment. A part by weight is desirable. If the content is too small, there is a concern that the printability is deteriorated due to a decrease in surface strength. If the content is too large, the viscosity of the coating liquid becomes high and high-concentration coating becomes difficult. Further, when the coating solution concentration is lowered, in order to obtain the same coating amount, a large amount of coating solution must be applied, which is not preferable because the drying load increases.

  In addition, when kaolin having an aspect ratio of 20 or more is contained, it is preferably used alone because it exhibits an effect due to its specific shape, but the aspect ratio is 20 or more with respect to 100 parts by weight of the total blending part of the pigment. If the inorganic pigment is 50 parts by weight or more, more preferably 80 parts by weight or more, it can be used in combination with various pigments.

The inclusion of a carboxyl group-containing resin in the heat-sensitive recording layer of the heat-sensitive recording material of the present invention is desirable because the adhesion between the protective layer and the heat-sensitive recording layer is improved and the water resistance at the boundary portion is improved. This is because the carboxyl group-containing resin contained in the heat-sensitive recording layer, a crosslinking reaction with epichlorohydrin resin and Po Riamin / amide resin contained in the protective layer, the protective layer and the heat sensitive recording It is estimated that the water resistance at the boundary of the layer is improved. In particular, when a carboxy-modified polyvinyl alcohol similar to the protective layer is used for the heat-sensitive recording layer, a remarkable effect is recognized. The carboxyl group-containing resin is desirably contained in an amount of 30% by weight or more based on the total binder of the thermosensitive recording layer.

  In addition, it is desirable that the thermosensitive recording layer of the thermosensitive recording material of the present invention contains an epichlorohydrin resin. By including the same epichlorohydrin-based resin as the component contained in the protective layer, the adhesion between the heat-sensitive recording layer and the protective layer is improved, and the immersion water resistance is improved. The epichlorohydrin resin is preferably added in an amount of 0.2 to 5.0 parts by weight (dry weight) in the heat-sensitive recording layer. When the amount of the epichlorohydrin resin added increases, the stability of the paint decreases.

  Next, various materials used in the present invention are exemplified, but binders, cross-linking agents, pigments and the like can be used in the protective layer as long as they do not impair the desired effects on the above-mentioned problems. It can also be used for each coating layer provided as needed, including layers.

  As the binder used in the present invention, fully saponified polyvinyl alcohol having a polymerization degree of 50 to 1900, partially saponified polyvinyl alcohol, acetoacetylated polyvinyl alcohol, carboxy-modified polyvinyl alcohol, amide-modified polyvinyl alcohol, sulfonic acid-modified polyvinyl alcohol, Butyral modified polyvinyl alcohol, olefin modified polyvinyl alcohol, nitrile modified polyvinyl alcohol, pyrrolidone modified polyvinyl alcohol, silicone modified polyvinyl alcohol, other modified polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, styrene-maleic anhydride copolymer, Styrene-butadiene copolymer and ethyl cellulose, acetyl Cellulose derivatives such as roulose, casein, arabic gum, oxidized starch, etherified starch, dialdehyde starch, esterified starch, polyvinyl chloride, polyvinyl acetate, polyacrylamide, polyacrylate, polyvinyl butyral, polystyrose and their Examples include copolymers, polyamide resins, silicone resins, petroleum resins, terpene resins, ketone resins, and coumaro resins. These polymer substances are used by dissolving them in solvents such as water, alcohol, ketones, esters, hydrocarbons, etc., and are used in the state of being emulsified or pasted in water or other media to achieve the required quality. It can also be used in combination.

  Examples of the crosslinking agent used in the present invention include glyoxal, methylol melamine, melamine formaldehyde resin, melamine urea resin, polyamine epichlorohydrin resin, polyamide epichlorohydrin resin, potassium persulfate, ammonium persulfate, sodium persulfate, chloride chloride Examples include ferric iron, magnesium chloride, borax, boric acid, alum, ammonium chloride and the like.

  Examples of the pigment used in the present invention include inorganic or organic fillers such as silica, calcium carbonate, kaolin, calcined kaolin, diatomaceous earth, talc, titanium oxide, and aluminum hydroxide. As the pigment used in the protective layer, aluminum hydroxide or kaolin is preferable in consideration of the wearability of the thermal head.

  Examples of the lubricant used in the present invention include fatty acid metal salts such as zinc stearate and calcium stearate, waxes, and silicone resins.

  Further, in the present invention, 4,4′-butylidene (6-tert-butyl-3-methylphenol) is used as an image stabilizer exhibiting an oil resistance effect of a recorded image and the like within a range that does not hinder a desired effect on the above problems. ), 2,2′-di-t-butyl-5,5′-dimethyl-4,4′-sulfonyldiphenol, 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) Butane, 1,1,3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 4-benzyloxy-4 ′-(2,3-epoxy-2-methylpropoxy) diphenyl sulfone, etc. Can also be added.

  In addition, benzophenone and triazole ultraviolet absorbers, dispersants, antifoaming agents, antioxidants, fluorescent dyes, and the like can be used.

  As the electron-donating leuco dye used in the present invention, those known in the conventional pressure-sensitive or heat-sensitive recording paper field can be used, and are not particularly limited, but include triphenylmethane compounds, fluorane compounds. Compounds, fluorene compounds, divinyl compounds and the like are preferable. Specific examples of typical colorless or light-colored dyes (dye precursors) are shown below. These dye precursors may be used alone or in combination of two or more.

<Triphenylmethane leuco dye>
3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also known as crystal violet lactone), 3,3-bis (p-dimethylaminophenyl) phthalide (also known as malachite green lactone)

<Fluoran leuco dye>
3-diethylamino-6-methylfluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7- (o, p-dimethylanilino) fluorane, 3-diethylamino- 6-methyl-7-chlorofluorane, 3-diethylamino-6-methyl-7- (m-trifluoromethylanilino) fluorane, 3-diethylamino-6-methyl-7- (o-chloroanilino) fluorane, 3- Diethylamino-6-methyl-7- (p-chloroanilino) fluorane, 3-diethylamino-6-methyl-7- (o-fluoroanilino) fluorane, 3-diethylamino-6-methyl-7- (m-methylanilino) fluorane 3-diethylamino-6-methyl-7-n-octylanilinofluorane, 3-di Tilamino-6-methyl-7-n-octylaminofluorane, 3-diethylamino-6-methyl-7-benzylaminofluorane, 3-diethylamino-6-methyl-7-dibenzylaminofluorane, 3-diethylamino- 6-chloro-7-methylfluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3-diethylamino-6-chloro-7-p-methylanilinofluorane, 3-diethylamino-6-ethoxy Ethyl-7-anilinofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7- (m-trifluoromethylanilino) fluorane, 3-diethylamino- 7- (o-chloroanilino) fluorane, 3-diethylamino-7- (p Chloroanilino) fluorane, 3-diethylamino-7- (o-fluoroanilino) fluorane, 3-diethylamino-benzo [a] fluorane, 3-diethylamino-benzo [c] fluorane, 3-dibutylamino-6-methyl-fluorane, 3-dibutylamino-6-methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-7- (o, p-dimethylanilino) fluorane, 3-dibutylamino-6-methyl-7- ( o-chloroanilino) fluorane, 3-dibutylamino-6-methyl-7- (p-chloroanilino) fluorane, 3-dibutylamino-6-methyl-7- (o-fluoroanilino) fluorane, 3-dibutylamino-6 -Methyl-7- (m-trifluoromethylanilino) fluorane, 3-dibutylamino- 6-methyl-7-chlorofluorane, 3-dibutylamino-6-ethoxyethyl-7-anilinofluorane, 3-dibutylamino-6-chloro-7-anilinofluorane, 3-dibutylamino-6- Methyl-7-p-methylanilinofluorane, 3-dibutylamino-7- (o-chloroanilino) fluorane, 3-dibutylamino-7- (o-fluoroanilino) fluorane, 3-di-n-pentylamino -6-methyl-7-anilinofluorane, 3-di-n-pentylamino-6-methyl-7- (p-chloroanilino) fluorane, 3-di-n-pentylamino-7- (m-trifluoro Methylanilino) fluorane, 3-di-n-pentylamino-6-chloro-7-anilinofluorane, 3-di-n-pentylamino-7- (p-chloro) Nirino) fluoran, 3-pyrrolidino-6-methyl-7-anilinofluoran, 3-piperidino-6-methyl-7-anilinofluoran

  3- (N-methyl-N-propylamino) -6-methyl-7-anilinofluorane, 3- (N-methyl-N-cyclohexylamino) -6-methyl-7-anilinofluorane, 3- (N-ethyl-N-cyclohexylamino) -6-methyl-7-anilinofluorane, 3- (N-ethyl-N-xylamino) -6-methyl-7- (p-chloroanilino) fluorane, 3- ( N-ethyl-p-toludino) -6-methyl-7-anilinofluorane, 3- (N-ethyl-N-isoamylamino) -6-methyl-7-anilinofluorane, 3- (N-ethyl) -N-isoamylamino) -6-chloro-7-anilinofluorane, 3- (N-ethyl-N-tetrahydrofurfurylamino) -6-methyl-7-anilinofluorane, 3- (N-ethyl) − -Isobutylamino) -6-methyl-7-anilinofluorane, 3- (N-ethyl-N-ethoxypropylamino) -6-methyl-7-anilinofluorane, 3-cyclohexylamino-6-chlorofluor Oran, 2- (4-oxahexyl) -3-dimethylamino-6-methyl-7-anilinofluorane, 2- (4-oxahexyl) -3-diethylamino-6-methyl-7-anilinofluorane 2- (4-oxahexyl) -3-dipropylamino-6-methyl-7-anilinofluorane, 2-methyl-6-p- (p-dimethylaminophenyl) aminoanilinofluorane, 2- Methoxy-6-p- (p-dimethylaminophenyl) aminoanilinofluorane, 2-chloro-3-methyl-6-p- (p-phenylaminophenyl) amino Anilinofluorane, 2-chloro-6-p- (p-dimethylaminophenyl) aminoanilinofluorane, 2-nitro-6-p- (p-diethylaminophenyl) aminoanilinofluorane, 2-amino- 6-p- (p-diethylaminophenyl) aminoanilinofluorane, 2-diethylamino-6-p- (p-diethylaminophenyl) aminoanilinofluorane, 2-phenyl-6-methyl-6-p- (p -Phenylaminophenyl) aminoanilinofluorane, 2-benzyl-6-p- (p-phenylaminophenyl) aminoanilinofluorane, 2-hydroxy-6-p- (p-phenylaminophenyl) aminoanilino Fluorane, 3-methyl-6-p- (p-dimethylaminophenyl) aminoanilinofluorane, 3-diethy Ruamino-6-p- (p-diethylaminophenyl) aminoanilinofluorane, 3-diethylamino-6-p- (p-dibutylaminophenyl) aminoanilinofluorane, 2,4-dimethyl-6-[(4 -Dimethylamino) anilino] -fluorane

<Fluorene leuco dye>
3,6,6′-tris (dimethylamino) spiro [fluorene-9,3′-phthalide], 3,6,6′-tris (diethylamino) spiro [fluorene-9,3′-phthalide], <divinyl series Leuco dye>
3,3-bis- [2- (p-dimethylaminophenyl) -2- (p-methoxyphenyl) ethenyl] -4,5,6,7-tetrabromophthalide, 3,3-bis- [2- (P-dimethylaminophenyl) -2- (p-methoxyphenyl) ethenyl] -4,5,6,7-tetrachlorophthalide, 3,3-bis- [1,1-bis (4-pyrrolidinophenyl) ) Ethylene-2-yl] -4,5,6,7-tetrabromophthalide, 3,3-bis- [1- (4-methoxyphenyl) -1- (4-pyrrolidinophenyl) ethylene-2- Yl] -4,5,6,7-tetrachlorophthalide

<Others>
3- (4-Diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide, 3- (4-diethylamino-2-ethoxyphenyl) -3- ( 1-octyl-2-methylindol-3-yl) -4-azaphthalide, 3- (4-cyclohexylethylamino-2-methoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl)- 4-azaphthalide, 3,3-bis (1-ethyl-2-methylindol-3-yl) phthalide, 3,6-bis (diethylamino) fluorane-γ- (3′-nitro) anilinolactam, 3,6 Bis (diethylamino) fluorane-γ- (4′-nitro) anilinolactam, 1,1-bis- [2 ′, 2 ′, 2 ″, 2 ″ -tetrakis- (p-dimethylamino) Enyl) -ethenyl] -2,2-dinitrileethane, 1,1-bis- [2 ′, 2 ′, 2 ″, 2 ″ -tetrakis- (p-dimethylaminophenyl) -ethenyl] -2- β-naphthoylethane, 1,1-bis- [2 ′, 2 ′, 2 ″, 2 ″ -tetrakis- (p-dimethylaminophenyl) -ethenyl] -2,2-diacetylethane, bis- [2, 2,2 ′, 2′-Tetrakis- (p-dimethylaminophenyl) -ethenyl] -methylmalonic acid dimethyl ester

  As the electron-accepting developer used in the present invention, all known ones in the field of conventional pressure-sensitive or heat-sensitive recording paper can be used, and are not particularly limited. For example, activated clay, attapulgite Inorganic acidic substances such as colloidal silica and aluminum silicate, 4,4′-isopropylidenediphenol, 1,1-bis (4-hydroxyphenyl) cyclohexane, 2,2-bis (4-hydroxyphenyl) -4-methyl Pentane, 4,4′-dihydroxydiphenyl sulfide, hydroquinone monobenzyl ether, benzyl 4-hydroxybenzoate, 4,4′-dihydroxydiphenyl sulfone, 2,4′-dihydroxydiphenyl sulfone, 4-hydroxy-4′-isopropoxy Diphenylsulfone, 4-hydroxy-4'-n-propoxy Phenylsulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, 4-hydroxy-4'-methyldiphenylsulfone, 4-hydroxyphenyl-4'-benzyloxyphenylsulfone, 3,4-dihydroxyphenyl-4'- Methylphenylsulfone, aminobenzenesulfonamide derivatives described in JP-A-8-59603, bis (4-hydroxyphenylthioethoxy) methane, 1,5-di (4-hydroxyphenylthio) -3-oxapentane, bis ( p-hydroxyphenyl) butyl acetate, methyl bis (p-hydroxyphenyl) acetate, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 1,4-bis [α-methyl-α- (4 ′ -Hydroxyphenyl) ethyl] benzene, 1,3-bis [α-methyl-α- ( '-Hydroxyphenyl) ethyl] benzene, di (4-hydroxy-3-methylphenyl) sulfide, 2,2'-thiobis (3-tert-octylphenol), 2,2'-thiobis (4-tert-octylphenol), Phenolic compounds such as diphenylsulfone cross-linking compounds described in International Publication WO 97/16420, compounds described in International Publication WO 02/081229 or JP 2002-301873, and N, N′-di-m-chlorophenylthiourea Thiourea compounds such as p-chlorobenzoic acid, stearyl gallate, zinc bis [4- (n-octyloxycarbonylamino) salicylate] dihydrate, 4- [2- (p-methoxyphenoxy) ethyloxy] salicylic acid , 4- [3- (p-Tolylsulfonyl) propyloxy] salici Aromatic carboxylic acids of phosphoric acid, 5- [p- (2-p-methoxyphenoxyethoxy) cumyl] salicylic acid, and zinc, magnesium, aluminum, calcium, titanium, manganese, tin, nickel, etc. of these aromatic carboxylic acids Examples thereof include salts with polyvalent metal salts, zinc antithiline complexes of zinc thiocyanate, and complex zinc salts of terephthalaldehyde acid with other aromatic carboxylic acids. These developers can be used alone or in combination of two or more. The diphenylsulfone cross-linking compound described in International Publication No. WO97 / 16420 is available as trade name D-90 manufactured by Nippon Soda Co., Ltd. Moreover, the compound as described in international publication WO02 / 081229 etc. is available as Nippon Soda Co., Ltd. brand name NKK-395 and D-100. In addition, a metal chelate color-developing component such as a higher fatty acid metal double salt and a polyvalent hydroxyaromatic compound described in JP-A-10-258577 can also be contained.

  As the sensitizer used in the heat-sensitive recording material of the present invention, a conventionally known sensitizer can be used. Examples of such sensitizers include fatty acid amides such as stearamide and palmitic acid amide, ethylene bisamide, montanic acid wax, polyethylene wax, 1,2-di- (3-methylphenoxy) ethane, p-benzylbiphenyl, β- Benzyloxynaphthalene, 4-biphenyl-p-tolyl ether, m-terphenyl, 1,2-diphenoxyethane, dibenzyl oxalate, di (p-chlorobenzyl) oxalate, di (p-methylbenzyl) oxalate, Dibenzyl terephthalate, benzyl p-benzyloxybenzoate, di-p-tolyl carbonate, phenyl-α-naphthyl carbonate, 1,4-diethoxynaphthalene, 1-hydroxy-2-naphthoic acid phenyl ester, o-xylene-bis -(Phenyl ether), 4- (m-methyl) Ruphenoxymethyl) biphenyl, 4,4′-ethylenedioxy-bis-benzoic acid dibenzyl ester, dibenzoyloxymethane, 1,2-di (3-methylphenoxy) ethylene, bis [2- (4-methoxy- Examples thereof include, but are not limited to, phenoxy) ethyl] ether, methyl p-nitrobenzoate, phenyl p-toluenesulfonate, and the like. These sensitizers may be used alone or in combination of two or more.

  The types and amounts of the electron-donating leuco dye, electron-accepting developer, and other various components used in the heat-sensitive recording material of the present invention are determined according to the required performance and recording suitability, and are not particularly limited. Usually, about 0.5 to 10 parts of an electron accepting developer and about 0.5 to 10 parts of a sensitizer are used with respect to 1 part of the electron donating leuco dye.

  By applying the coating liquid having the above composition to any support such as paper, recycled paper, synthetic paper, film, plastic film, foamed plastic film, non-woven fabric, etc., the desired thermal recording material can be obtained. Moreover, you may use the composite sheet which combined these as a support body.

Electron-donating leuco dye, electron-accepting developer, and materials to be added as necessary are finely divided to a particle size of several microns or less by a pulverizer such as a ball mill, an attritor, or a sand glider, or an appropriate emulsifier. Depending on the binder and purpose, various additive materials are added to form a coating solution. The means for applying is not particularly limited, and can be applied in accordance with a well-known conventional technique. For example, various coaters such as an air knife coater, a rod blade coater, a vent blade coater, a bevel blade coater, a roll coater, and a curtain coater are provided. An off-machine coating machine or an on-machine coating machine is appropriately selected and used. The coating amount of the heat-sensitive recording layer is not particularly limited and is usually in the range of ² to 12 g / m ^{2 by} dry weight. Further, the coating amount of the protective layer provided on the thermosensitive recording layer is not particularly limited, and is usually in the range of 1 to 5 g / m ² .

The heat-sensitive recording material of the present invention can further be provided with an undercoat layer such as a polymer material containing a filler under the heat-sensitive recording layer for the purpose of increasing the color development sensitivity. It is also possible to correct the curl by providing a backcoat layer on the opposite side of the support from the thermosensitive recording layer. Further, various known techniques in the heat-sensitive recording material field can be added as appropriate, such as applying a smoothing process such as supercalendering after coating each layer.

  The thermosensitive recording material of the present invention will be described below with reference to examples. In the description, parts and% indicate parts by weight and% by weight, respectively. Various solutions, dispersions, or paints were prepared as follows.

[Synthesis of carboxy-modified polyvinyl alcohol]
A polymerization can equipped with a reflux condenser, a stirrer, a thermometer, a nitrogen inlet tube, a post-addition liquid inlet and a pump was charged with a 10% methanol solution of vinyl acetate, methanol and maleic acid. While stirring the polymerization solution, the system was purged with nitrogen and heated in a thermostatic bath. When the temperature reached 60 ° C, 2,2'-azobisisobutyronitrile was added to the system together with methanol to start polymerization. did. From the start of polymerization, a 10% methanol solution of maleic acid was added to P J. Hanna (Industrial and Enginnering Chemistry. Vol 4,9. N0.2 pages 208-209 (1957)) while analyzing the solids concentration of the polymerization system. Polymerization was allowed to proceed while dropping according to the method according to the submitted formula. A 10% methanol solution of maleic acid was dropped almost uniformly, and then thiourea was added to terminate the polymerization. Methanol vapor was blown into the polymerization paste to remove unreacted vinyl acetate monomer, and a methanol solution of vinyl acetate-maleic acid copolymer (maleic acid unit content: 5 mol%) was obtained.

  Next, a 10% methanol solution of sodium hydroxide was added to the solution prepared by adjusting the copolymer concentration of methanol with methanol at 40 ° C. while stirring, so that the saponification degree was 85 to 90. The gel-like material was pulverized, washed with methanol, and dried to obtain white powders of carboxy-modified polyvinyl alcohols A to E. The degree of polymerization of carboxy-modified polyvinyl alcohol was adjusted by the concentration of vinyl acetate at the time of preparation, and the degree of polymerization was measured using GPC.

Carboxy-modified polyvinyl alcohol A Degree of polymerization: 600
Carboxy-modified polyvinyl alcohol B degree of polymerization: 1100
Carboxy-modified polyvinyl alcohol C Degree of polymerization: 350
Carboxy-modified polyvinyl alcohol D Degree of polymerization: 1700
Carboxy-modified polyvinyl alcohol E Degree of polymerization: 100

[Example 1]
A composition comprising the following composition was stirred and dispersed to prepare an undercoat layer coating solution.
U solution (undercoat layer coating solution)
Firing kaolin (trade name: Ensilex 90 manufactured by Engelhard)
100 parts Styrene-butadiene copolymer latex (solid content 48%) 40 parts Fully saponified polyvinyl alcohol (trade name: PVA117, manufactured by Kuraray Co., Ltd.)
10% aqueous solution 30 parts Water 160 parts Next, after applying the undercoat layer coating solution to one side of the support (60 g / m ² base paper), drying is performed, and the undercoat layer is applied in an amount of 10.0 g / m ² . Coated paper was obtained.

Developer liquid dispersion (A liquid), leuco dye dispersion liquid (B liquid), and sensitizer dispersion liquid (C liquid) of the following composition are each separately separately with a sand grinder until the average particle diameter becomes 0.5 microns. Wet grinding was performed.
Liquid A (developer dispersion)
4-hydroxy-4'-isopropoxydiphenylsulfone 6.0 parts polyvinyl alcohol 10% aqueous solution 18.8 parts water 11.2 parts Liquid B (basic colorless dye dispersion)
3-Dibutylamino-6-methyl-7-anilinofluorane (ODB-2)
2.0 parts polyvinyl alcohol 10% aqueous solution 4.6 parts water 2.6 parts C liquid (sensitizer dispersion)
Dibenzyl oxalate 6.0 parts Polyvinyl alcohol 10% aqueous solution 18.8 parts Water 11.2 parts Subsequently, the dispersion was mixed at the following ratio to obtain a coating solution for the thermosensitive recording layer.

Thermal recording layer coating liquid A liquid (developer dispersion) 36.0 parts B liquid (leuco dye dispersion) 13.8 parts C liquid (sensitizer dispersion) 36.0 parts Carboxy-modified polyvinyl alcohol (Kuraray) (Product name: KL118)
25% 10% aqueous solution polyamide epichlorohydrin resin (trade name: WS4020, manufactured by Seiko PMC)
(25% solid content, degree of cationization: 2.7, molecular weight: 2.2 million, quaternary amine)
0.8 parts Next, the heat-sensitive recording layer coating liquid was applied onto the undercoat layer of the undercoat layer-coated paper so as to have a coating amount of 6.0 g / m ^2, and then dried and heat-sensitive recording layer-coated paper. Got.

Subsequently, it mixed by the following ratio and was set as the coating liquid of the protective layer.
Aluminum hydroxide (50% dispersion) 9.0 parts Carboxyl-modified polyvinyl alcohol A (degree of polymerization: 600) 10% aqueous solution
30 parts Zinc stearate (trade name: Hydrin Z-7-30, solid content 30%, manufactured by Chukyo Yushi Co., Ltd.)
2.0 parts polyamide epichlorohydrin resin (trade name: WS4020, manufactured by Seiko PMC)
(25% solid content, degree of cationization: 2.7, molecular weight: 2.2 million, quaternary amine)
2.0 parts modified polyamine resin (trade name: Sumirez Resin SPI-102A, solid content 25%, manufactured by Sumitomo Chemical Co., Ltd.)
0.9 parts Next, after coating the protective layer coating liquid on the heat-sensitive recording layer of the heat-sensitive recording layer-coated paper so that the coating amount is 3.0 g / m ² , drying is performed, and this sheet is coated with a super calendar. A heat-sensitive recording material was obtained by processing so that the smoothness was 1000 to 2000 seconds.

[Example 2]
A heat-sensitive recording material was prepared in the same manner as in Example 1 except that the carboxy-modified polyvinyl alcohol blended in the protective layer coating liquid of Example 1 was changed to another carboxy-modified polyvinyl alcohol B (degree of polymerization: 1100).

[Example 3]
A heat-sensitive recording material was produced in the same manner as in Example 1 except that the carboxy-modified polyvinyl alcohol blended in the protective layer coating liquid of Example 1 was changed to another carboxy-modified polyvinyl alcohol C (degree of polymerization: 350).

[Example 4]
Aluminum hydroxide (50% dispersion) blended in the protective layer coating liquid of Example 1 was kaolin (trade name: Konza 1500, manufactured by Imeris Co., Ltd., aspect ratio: 60, average particle size: 2.5 μm, oil absorption: 45 ml. / 100 g) A heat-sensitive recording material was prepared in the same manner as in Example 1 except that it was changed to (50% dispersion).

[Example 5]
A thermosensitive recording medium was prepared in the same manner as in Example 1 except that the modified polyamine resin blended in the protective layer coating liquid of Example 1 was changed to a modified polyimine resin (trade name: CP8994, manufactured by Seiko PMC, 25% solid content). Created.

[Comparative Example 1]
A heat-sensitive recording material was produced in the same manner as in Example 1 except that the carboxy-modified polyvinyl alcohol blended in the protective layer coating liquid of Example 1 was changed to another carboxy-modified polyvinyl alcohol D (degree of polymerization: 1700).

[Comparative Example 2]
The carboxy-modified polyvinyl alcohol blended in the protective layer coating liquid of Example 1 was changed to another carboxy-modified polyvinyl alcohol D (degree of polymerization: 1700), and the modified polyamine resin blended in the protective layer coating liquid was further modified polyimine resin ( A heat-sensitive recording material was prepared in the same manner as in Example 1 except that the product was changed to Starlight PMC Co., Ltd. (trade name: CP8994, solid content 25%).

[Comparative Example 3]
A heat-sensitive recording material was prepared in the same manner as in Example 1 except that the carboxy-modified polyvinyl alcohol blended in the protective layer coating liquid of Example 1 was changed to another carboxy-modified polyvinyl alcohol E (degree of polymerization: 100).

[Comparative Example 4]
A heat-sensitive recording material was prepared in the same manner as in Example 1 except that the modified polyamine resin was not blended.

[Comparative Example 5]
A heat-sensitive recording material was prepared in the same manner as in Example 1 except that the polyamide epichlorohydrin resin was not blended.

[Comparative Example 6]
Heat sensitive recording material as in Example 1 except that the polyamide epichlorohydrin resin and the modified polyamine resin blended in the protective layer coating liquid of Example 1 were not blended, and 2.5 parts of a 40% aqueous solution of glyoxal was blended instead. It was created.

<Recording sensitivity evaluation>
About the created thermal recording body, it printed with the applied energy of 0.41 mJ / dot using TH-PMD (Thermal recording printing tester, the Kyocera thermal head mounting | wearing) made from Okura Electric. The recording density of the recording part was measured with a Macbeth densitometer (RD-914, using an amber filter).
<Water resistance evaluation>

10 μl of water was dropped on the recording surface of the heat-sensitive recording medium, folded in half so that the recording surface was inside, and a 100 g / cm ² load was placed on the recording medium on which water droplets were dropped, and the environment was 40 ° C. and 90% RH. Then, the recording surface was peeled off and the blocking was evaluated. The evaluation criteria are shown below.
A: No blocking at all O: Slight peeling sound but no blocking Δ: Slight blocking is observed X: Blocking occurs and a part of the recording layer is peeled off

<Printability>
Using the Okura Electric TH-PMD (a thermal recording paper printing tester, equipped with a thermal head manufactured by Kyocera), the head casks when printing was performed on the created thermal recording medium with an applied energy of 0.41 mJ / dot. The presence or absence of adhesion was evaluated according to the following criteria.
◎: No head scum is observed. ◯: Head scum is hardly observed. △: Head scum is slightly observed. X: Head scum is remarkably observed.

Claims (3)

On and Aru colorless or heat-sensitive recording layer containing a light-colored electron-donating leuco dye and electron accepting color developing agent provided on a support, heat-sensitive recording material comprising sequentially laminating a protective layer, the polymerization in the protective layer degrees will contain a carboxy-modified polyvinyl alcohol resin 300 to 1200, Oyo epichlorohydrin resin beauty Po Riamin / amide resins (excluding epichlorohydrin resin), heat-sensitive recording layer is Epikurorohido A heat-sensitive recording material comprising a phosphorous resin . The heat-sensitive recording material according to claim 1 which is contained in the protective layer Lupo Riamin / amide resin is characterized in that it is a polyamine resin. The heat-sensitive recording material according to claim 1 or 2, wherein the protective layer contains kaolin having an aspect ratio of 20 or more.