JP2009083181A - Thermosensitive recording body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermosensitive recording body which has high color development performance and is excellent in heat resistance, plasticizer resistance, water resistance and printing running performance (anti-sticking property). <P>SOLUTION: In the thermosensitive recording body, a thermosensitive recording layer comprising primarily a colorless or light-colored electron-donating leuco dye and an electron accepting developer and a protective layer are disposed on a substrate in the order, wherein an aqueous polyurethane-based resin and an epichlorohydrin-based resin are included in the protective layer. Further, polyamine/amide-based resin is included in the protective layer, so that an excellent effect can be developed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a heat-sensitive recording material having high color development sensitivity and excellent heat resistance, plasticizer resistance, and water resistance.

  In general, a thermosensitive recording comprising as a main component a colorless or light-colored electron-donating leuco dye (hereinafter referred to as a dye) and an electron-accepting developer (hereinafter referred to as a developer) that reacts with the dye to develop a color when heated. Thermal recording materials having layers have been widely put into practical use. In order to perform recording on this thermal recording medium, a thermal printer or the like with a built-in thermal head is used. Compared with other recording systems that have been put to practical use, this thermal recording system has no noise during recording, does not require development and fixing, is maintenance-free, is relatively inexpensive, and is compact. Due to the very vivid color produced, it is widely used in facsimiles, computer terminal printers, automatic ticket vending machines, measuring recorders, handy terminals used outdoors, and the like.

  In addition to the above-mentioned output sheets of various devices, the thermal recording medium is widely used in fields such as cash voucher sheets that require high storage stability. Conventionally, thermal recording media have been required to have characteristics such as sensitivity and image storability, but they are required when used for cash vouchers, etc. There is a need for a heat-sensitive recording material having image storability such as heat resistance, water resistance and plasticizer resistance.

  For this reason, conventionally, a method of providing a protective layer on a thermosensitive coloring layer is widely known, and Patent Document 1 discloses a thermosensitive recording material containing a polyurethane ionomer in the protective layer. Patent Document 2 discloses a heat-sensitive recording material containing a water-dispersed urethane resin having a specific softening point, glass temperature, and average particle diameter in a protective layer.

JP-A-5-8542 JP 2001-26181 A

  However, a thermal recording medium containing a polyurethane ionomer or a water-dispersed urethane resin in the protective layer has a printing runnability because the aqueous polyurethane resin melts or softens due to heat from the thermal head during printing. In particular, a problem occurs in stick resistance. In addition, with the expansion of applications of thermal recording materials, further improvements in quality are also required in heat resistance, plasticizer resistance, and water resistance. Accordingly, an object of the present invention is to provide a heat-sensitive recording material that has high color development sensitivity and is excellent in heat resistance, plasticizer resistance, water resistance, and print running property (stick resistance).

  As a result of researches to solve the above problems, the present inventor has found that the problems can be solved by using the following configuration. That is, the present invention provides a heat-sensitive recording material comprising a support and a heat-sensitive recording layer comprising a colorless or light-colored electron-donating leuco dye and an electron-accepting developer as main components and a protective layer in this order. A heat-sensitive recording material comprising an aqueous polyurethane-based resin and an epichlorohydrin-based resin in a layer. Furthermore, by including a polyamine resin and / or a polyamide resin (hereinafter referred to as polyamine / amide resin) in the protective layer, an excellent effect is exhibited.

  The heat-sensitive recording material of the present invention is a heat-sensitive recording material in which a heat-sensitive recording layer containing a colorless or light-colored electron-donating leuco dye and an electron-accepting developer as main components and a protective layer are provided in this order on a support. The protective layer contains an aqueous polyurethane-based resin and an epichlorohydrin-based resin. Further, a polyamine / amide resin is further included in the protective layer to achieve a better effect. be able to.

  In the present invention, the aqueous polyurethane resin is a polymer compound obtained by copolymerizing a monomer with a urethane bond formed by condensation of an isocyanate group and an alcohol group, such as an ester polyurethane resin, an ether polyurethane resin, a carbonate polyurethane resin, etc. Water-solubility can be obtained by partially binding metal salt or ammonium salt such as carboxylic acid or sulfonic acid to emulsion type polyurethane resin, ester type polyurethane resin, ether type polyurethane resin, carbonate type polyurethane resin etc. emulsified with emulsifier. The ionomer-type polyurethane resin provided can be exemplified. From the viewpoint of water resistance, plasticizer resistance, heat resistance, and color development sensitivity, an emulsion obtained by emulsifying an ester polyurethane resin having a carboxyl group. It is desirable to use a type polyurethane resin or an ionomer type polyurethane resins, it is further preferable to use a polyurethane ionomer resins. In the present invention, although the reason is not clear, a thermal recording material having high color development sensitivity can be obtained by incorporating these aqueous polyurethanes into the protective layer.

  Examples of the epichlorohydrin 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), WS4030 (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, the modified polyamine / amide resin is a polyamide urea resin, polyethylene imine resin, polyalkylene polyamine resin, polyalkylene polyamide resin, polyamine polyurea resin, modified polyamine resin, modified polyamide resin, polyalkylene polyamine urea formalin. Resin, polyalkylene polyamine polyamide polyurea resin, and the like are listed. Specific examples include Sumire Resin 302 (manufactured by Sumitomo Chemical Co., Ltd .: polyamine polyurea resin) and Sumire Resin 712 (manufactured by Sumitomo Chemical Co., Ltd .: polyamine polyurea resin). ), Sumire Resin 703 (manufactured by Sumitomo Chemical: polyamine polyurea resin), Sumire Resin 636 (manufactured by Sumitomo Chemical: polyamine polyurea resin), Sumire Resin SPI-100 (manufactured by Sumitomo Chemical: modified polyamine) Tree ), Sumire Resin SPI-102A (Sumitomo Chemical Co .: modified polyamine resin), Sumire Resin SPI-106N (Sumitomo Chemical Co .: modified polyamide resin), Sumire Resin SPI-203 (50) (Sumitomo Chemical Co., Ltd.) : Polyamide resin), Sumirez resin SPI-198 (manufactured by Sumitomo Chemical Co., Ltd .: polyamide resin), printable A-700 (manufactured by Asahi Kasei), printable A-600 (manufactured by Asahi Kasei), PA6500 (manufactured by Seiko PMC): Polyalkylene polyamine urea formalin resin), PA6504 (manufactured by Starlight PMC: polyalkylene polyamine urea formalin resin), PA6664, PA6638, PA6640, PA6664, PA6664, PA6654, PA6702, PA6704 (above, manufactured by Starlight PMC: polyalkylenepolyamide) Polyamide polyurea resin), CP8994 (manufactured by Seiko PMC: polyethyleneimine resin), and the like. Although not particularly limited, polyamine resins (polyalkylene polyamine resins, polyamine polyurea resins) are considered in terms of color development sensitivity. It is desirable to use a modified polyamine resin, polyalkylene polyamine urea formalin resin, polyalkylene polyamine polyamide polyurea resin).

In the present invention, the reason for the excellent effect is considered as follows.
In the protective layer of the heat-sensitive recording material of the present invention, the hydrophilic groups of both the aqueous polyurethane resin and the epichlorohydrin resin are reacted by reacting the carboxyl group of the aqueous urethane resin with the amine or amide part of the epichlorohydrin resin. Water resistance is imparted to make the part hydrophobic. In addition, epichlorohydrin resin reacts with a binder having a carboxyl group or a hydroxyl group other than the aqueous polyurethane resin in the protective layer, so the binder (including the aqueous polyurethane resin) in the protective layer is an apparently huge polymer. Since the similar behavior is exhibited, the heat resistance, plasticizer resistance, and print running property (stick resistance) of the entire protective layer are improved.

  Furthermore, by including a polyamine / amide resin in the protective layer, the hydrophilic part of the polyamine / amide resin and the hydrophilic reaction part formed of the urethane resin and epichlorohydrin resin attract each other. This cross-linked site is encased with the hydrophobic group of the modified polyamine / amide resin outside, that is, the hydrophilic reactive site is protected from water by the hydrophobic group, and high water resistance is exhibited. The polyamine / polyamide resin is attracted to the hydrophilic part of the binder (including aqueous polyurethane resin) having a carboxyl group or a hydroxyl group in the protective layer, and the binder having the carboxyl group or hydroxyl group is a hydrophobic group of the polyamine / amide resin. , And with a binder (including an aqueous polyurethane resin) in which the cationic part of the polyamine / amide resin has a carboxy, the water resistance, heat resistance, It is presumed that plasticizer resistance and printing runnability (stick resistance) can be obtained.

  The blending ratio of the aqueous polyurethane resin is not particularly limited, but an excellent effect is exhibited by containing 5% by weight or more, more preferably 20% by weight or more with respect to all the binders in the protective layer. In addition, there is no restriction | limiting in particular in the binder which can be used together with water-based polyurethane resin, complete saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, carboxy modified polyvinyl alcohol, amide modified polyvinyl alcohol, sulfonic acid modified polyvinyl alcohol, butyral modified polyvinyl alcohol, other Modified polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, ethyl cellulose, cellulose derivatives such as acetyl cellulose, styrene-maleic anhydride copolymer, styrene-butadiene copolymer, polyvinyl chloride, polyvinyl acetate, polyacrylamide , Polyacrylate, polyvinyl butyllar, polystyrene and their copolymers, polyamide resin, silicon Examples thereof include fats, petroleum resins, terpene resins, ketone resins, and coumaro resins. From the viewpoint of plasticizer resistance and reactivity with epichlorohydrin resins and polyamine / amide resins, carboxy-modified polyvinyl alcohol can be used. It is desirable to use together.

  The content of the epichlorohydrin resin and the modified polyamine / amide resin used in the present invention is preferably 1 to 100 parts by weight with respect to 100 parts by weight of the total binder (including the aqueous polyurethane resin), More preferably, it is 5 to 50 parts by weight. If the content is too small, the crosslinking reaction becomes insufficient and good water resistance cannot be obtained. If the content is too large, there arises a problem in operability due to an increase in viscosity of the coating liquid or gelation. Moreover, since epichlorohydrin resin cross-links at pH 6.0 or higher, it is desirable to adjust the pH of the protective layer coating to 6.0 or higher.

  It is desirable that the heat-sensitive recording layer of the heat-sensitive recording material of the present invention contains a carboxyl group-containing resin (including an aqueous polyurethane resin) and / or an epichlorohydrin resin. By including it in the heat-sensitive recording layer, the adhesion between the heat-sensitive recording layer and the protective layer is improved, and the immersion water resistance is improved. 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. The epichlorohydrin resin is preferably added in an amount of 0.2 to 5.0 parts by weight (dry weight) when the entire thermosensitive recording layer is 100 parts by weight (dry weight). When the amount of the epichlorohydrin resin added increases, the stability of the paint decreases. From the viewpoint of water resistance, it is desirable to contain an emulsion type polyurethane resin obtained by emulsifying an ester-based polyurethane resin having a carboxyl group, an ionomer type polyurethane resin, a carboxyl group-containing resin, and carboxy-modified polyvinyl alcohol from the viewpoint of color development sensitivity. Is desirable.

  Examples of various materials used in the heat-sensitive recording material of the present invention include a binder and a cross-linking agent that can be used in the protective layer as long as the desired effects on the above problems are not impaired. It can be used not only for the protective layer but also for each coating layer provided as necessary, including a heat-sensitive recording layer and an under layer.

  As the developer used in the present invention, any known ones in the field of conventional pressure-sensitive or heat-sensitive recording paper can be used and are not particularly limited. For example, 4,4′-isopropyl Dendiphenol, 1,1-bis (4-hydroxyphenyl) cyclohexane, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 4,4′-dihydroxydiphenyl sulfide, hydroquinone monobenzyl ether, 4-hydroxy Benzyl benzoate, 4,4′-dihydroxydiphenylsulfone, 2,4′-dihydroxydiphenylsulfone, 4-hydroxy-4′-isopropoxydiphenylsulfone, 4-hydroxy-4′-n-propoxydiphenylsulfone, bis (3 -Allyl-4-hydroxyphenyl) sulfone, 4-hydroxy -4'-allyloxydiphenylsulfone, 4-hydroxy-4'-methyldiphenylsulfone, 4-hydroxyphenyl-4'-benzyloxyphenylsulfone, 3,4-dihydroxyphenyl-4'-methylphenylsulfone, JP-A-8 Aminobenzenesulfonamide derivatives described in Japanese Patent No. -59603, bis (4-hydroxyphenylthioethoxy) methane, 1,5-di (4-hydroxyphenylthio) -3-oxapentane, butyl bis (p-hydroxyphenyl) 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- (4′-hydroxyphenyl) Ethyl] benzene, di (4-hydroxy-3-methylphenyl) sulfide, 2,2′-thiobis (3-tert-octylphenol), 2,2′-thiobis (4-tert-octylphenol), International Publication WO 97/16420 Phenolic compounds such as diphenylsulfone cross-linking compounds described in No. 4, developer compositions described in International Publication WO 02/098774, compounds described in International Publication WO 02/081229 or JP-A No. 2002-301873, 4, 4′-bis-3- (phenoxycarbonylamino) methylphenylureido) diphenylsulfone (trade name: UU manufactured by Asahi Kasei Co., Ltd.), thiourea compounds such as N, N′-di-m-chlorophenylthiourea, p-chlorobenzoic acid, Stearyl gallate, bis [4- (n-octyloxycarbonylamino) Zinc salicylate] dihydrate, 4- [2- (p-methoxyphenoxy) ethyloxy] salicylic acid, 4- [3- (p-tolylsulfonyl) propyloxy] salicylic acid, 5- [p- (2-p-methoxy) Phenoxyethoxy) cumyl] aromatic carboxylic acids of salicylic acid, and salts of these aromatic carboxylic acids with polyvalent metal salts such as zinc, magnesium, aluminum, calcium, titanium, manganese, tin, nickel, and further zinc thiocyanate Antipyrine complexes of the above, and complex zinc salts of terephthalaldehyde acid and other aromatic carboxylic acids. A phenolic compound such as the diphenylsulfone cross-linking compound described in International Publication No. WO 97/16420 is available as a trade name D-90 manufactured by Nippon Soda Co., Ltd. The compounds described in International Publication No. WO02 / 081229 or JP-A-2002-301873 are available as trade names D-102 and D-100 manufactured by Nippon Soda Co., Ltd. These developers can be used alone or in combination of two or more. Among these, 4-hydroxy-4'-isopropoxydiphenyl sulfone is particularly preferable because of excellent color development sensitivity. 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 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; 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-diethylamino-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-ethoxyethyl-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-dibutylamino-6-methyl-7- (o); 3-dibutylamino-6-methyl-7- (o; 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-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- 3-di-n-pentylamino-6-methyl-7-anilinofluorane; 3-di-n-pentylamino-6-methyl-7- (p-chloroanilino) fluorane; Di-n-pentylamino-7- (m-trifluoromethylanilino) fluorane; 3-di-n-pentylamino-6-chloro-7-anilinofluorane; 3-di-n-pentylamino-7 -(P-chloroanilino) fluorane; 3-pyrrolidino-6-methyl-7-anilinofluorane; 3-piperidino-6-methyl-7-anilinofluorane 3- (N-methyl-N-propylamino) -6-methyl-7-anilinofluorane; 3- (N-methyl-N-cyclohexylamino) -6-methyl-7-anilinofluorane; -(N-ethyl-N-cyclohexylamino) -6-methyl-7-anilinofluorane; 3- (N-ethyl-N-xylamino) -6-methyl-7- (p-chloroanilino) fluorane; (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; Til-N-isobutylamino) -6-methyl-7-anilinofluorane; 3- (N-ethyl-N-ethoxypropylamino) -6-methyl-7-anilinofluorane; 3-cyclohexylamino-6 -Chlorofluorane; 2- (4-oxahexyl) -3-dimethylamino-6-methyl-7-anilinofluorane; 2- (4-oxahexyl) -3-diethylamino-6-methyl-7-ani Linofluorane; 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); 2-chloro-6-p- (p-dimethylaminophenyl) aminoanilinofluorane; 2-nitro-6-p- (p-diethylaminophenyl) aminoanilinofluorane; -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) Aminoanilinofluorane; 3-methyl-6-p- (p-dimethylaminophenyl) aminoanilinov Oran; 3-diethylamino-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 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)- 3,3-bis (1-ethyl-2-methylindol-3-yl) phthalide; 3,6-bis (diethylamino) fluorane-γ- (3′-nitro) anilinolactam; -Bis (diethylamino) fluorane-γ- (4'-nitro) anilinolactam; 1,1-bis- [2 ', 2', 2 ", 2" -tetrakis- (p-dimethyla Nophenyl) -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 binder used in the present invention, generally known binders are used. Polyvinyl alcohol, partially saponified polyvinyl alcohol, carboxy modified polyvinyl alcohol, amide modified polyvinyl alcohol, sulfonic acid modified polyvinyl alcohol, butyral modified poly Vinyl alcohol, other modified polyvinyl alcohol, cellulose derivatives such as hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, ethyl cellulose, acetyl cellulose, styrene-maleic anhydride copolymer, styrene-butadiene copolymer, polyvinyl chloride, poly Examples thereof include vinyl acetate, polyacrylamide, polyacrylic ester, polyvinyl butyllar, polystyrene and copolymers thereof, polyamide resin, silicon resin, petroleum resin, terpene resin, ketone resin, and coumaro resin. The binder used in the protective layer is preferably carboxy-modified polyvinyl alcohol from the viewpoint of plasticizer resistance.

These polymer substances are used by dissolving them in water, alcohol, ketones, esters, hydrocarbons and other solvents, and are used in the form of emulsification or paste dispersion in water or other media to achieve the required quality. It is also possible to use it together.
As a compounding quantity of a binder, 1 to 30 weight% is preferable with respect to the heat-sensitive layer total solid. When the blending amount of the binder is 1% by weight or less, the water resistance and surface strength are low, and when it is 30% by weight or more, high color development sensitivity is difficult to obtain.

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

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

  Moreover, in this invention, a conventionally well-known sensitizer can be used in the range which does not inhibit the desired effect with respect to the said subject. Such sensitizers include 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, 4,4′-ethylenedioxy-bis-benzoic acid dibenzyl ester, dibenzoyloxymethane, 1,2-di (3-methylphenoxy) ethylene, 1 , 2-diphenoxyethylene, bis [2- (4-methoxy-phenoxy) ethyl] ether, methyl p-nitrobenzoate, dibenzyl oxalate, di (p-chlorobenzyl) oxalate, di (p-methyl oxalate) Benzyl), dibenzyl terephthalate, benzyl p-benzyloxybenzoate, di-p-to Carbonate, phenyl-α-naphthyl carbonate, 1,4-diethoxynaphthalene, 1-hydroxy-2-naphthoic acid phenyl ester, 4- (m-methylphenoxymethyl) biphenyl, orthotoluenesulfonamide, paratoluenesulfonamide. Although it can illustrate, it is not restrict | limited in particular to these. These sensitizers may be used alone or in combination of two or more.

  Examples of the filler 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, and these are used alone or in combination of two or more. Can be used.

  In the present invention, 4,4′-butylidene (6-tert-butyl-3-methylphenol) is used as a stabilizer for imparting oil resistance and the like of recorded images within a range that does not impair the desired effect on the above-described 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-butylphenylbutane, 4-benzyloxy-4 '-(2,3-epoxy-2-methylpropoxy) diphenylsulfone, epoxy resin Etc. can also be added.

  The types and amounts of the basic leuco dye, developer, and other various components used in the heat-sensitive recording material of the present invention are determined according to required performance and recording suitability, and are not particularly limited. A developer of 0.5 to 10 parts, a sensitizer of 0.5 to 10 parts, and a filler of about 0.5 to 10 parts are used with respect to 1 part of the functional 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. Basic leuco dye, color developer, and materials to be added as necessary are finely pulverized to a particle size of several microns or less by a pulverizer such as a ball mill, attritor or sand glider, or an appropriate emulsifying device. Depending on the conditions, various additive materials are added to obtain a coating solution. The means for applying is not particularly limited, and can be applied in accordance with well-known conventional techniques. For example, an off-knife equipped with various coaters such as an air knife coater, a rod blade coater, a bill blade coater, a roll coater, a curtain coater, and a spray coater. A machine coater or an on-machine coater 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.

  In the heat-sensitive recording material of the present invention, an undercoat layer such as a polymer material containing a filler can be provided 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. Also, 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 heat-sensitive recording material of the present invention will be described below by examples. All examples are given on a weight basis.
[Preparation of precoat paint]
Under layer coating liquid -calcined kaolin (Ansilex 90 manufactured by Engelhard) 90.0 parts-Styrene-butadiene copolymer latex (solid content 50%) 10.0 parts-Water 50.0 parts A mixture comprising the above composition The under layer coating solution was prepared by mixing and stirring.

Thermosensitive coloring layer coating liquid The following A liquid to C liquid were separately wet-ground with a sand grinder until the average particle size became 0.5 μm.
Liquid A (electron-accepting developer dispersion)
-4-hydroxy-4'-isopropoxydiphenyl sulfone (Nippon Soda Co., Ltd., trade name: D-8) 6.0 parts-polyvinyl alcohol 10% aqueous solution 18.8 parts-water 11.2 parts B solution (basic Colorless dye dispersion)
-3-dibutylamino-6-methyl-7-anilinofluorane (manufactured by Yamamoto Kasei Co., Ltd., trade name: ODB-2) 3.0 parts-polyvinyl alcohol 10% aqueous solution 6.9 parts-water 3.9 parts C Liquid (sensitizer dispersion)
-1,2-bis (phenoxymethyl) benzene (manufactured by Nikka Chemical Co., Ltd., trade name: PMB-2) 6.0 parts-polyvinyl alcohol 10% aqueous solution 18.8 parts-water 11.2 parts water A 50 parts, 80 parts of B liquid, 40 parts of C liquid, 25 parts of silicic acid (manufactured by Mizusawa Chemical Co., Ltd., Mizukasil P527), 50 parts of 10% carboxyl-modified PVA solution (manufactured by Kuraray Co., Ltd., PVA-KL318), polyamide epichlorohydrin liquid (Starlight PMC) WS4020) was added, and 280 parts of water was further added and stirred to prepare a thermosensitive coloring layer coating material.

[Preparation of protective coating]
Protective layer paint 1
-10% carboxyl-modified PVA solution (PVA-KL318) 50 parts-Aqueous polyurethane resin (Dainippon Ink & Chemicals, Hydran AP40N, ionomer type) 50 parts-25% polyamide epichlorohydrin solution (WS4020) 10 parts -45 % Modified polyamide resin solution (Sumitomo Chemical Co., Ltd., Sumirez resin SPI106N)
10 parts-20% silicic acid dispersion (Mizusawa Chemical Co., Ltd., Mizukasil P527) 50 parts-40% zinc stearate emulsion liquid (manufactured by Chukyo Yushi Co., Ltd., Hydrin E-366)
5 parts were stirred and mixed.

Protective layer paint 2
-10% carboxyl modified PVA solution (PVA-KL318) 70 parts-aqueous polyurethane resin (Hydran AP40N) 30 parts-25% polyamide epichlorohydrin solution (WS4020) 10 parts-45% modified polyamide resin solution (Smileds resin SPI106N) ) 10 parts-20% silicic acid dispersion liquid (Mizukasil P527) 50 parts-40% zinc stearate emulsion liquid (hydrin E-366) 5 parts were stirred and mixed.

Protective layer paint 3
-10% carboxyl-modified PVA solution (PVA-KL318) 70 parts-Aqueous polyurethane resin (manufactured by Dainippon Ink & Chemicals, Hydran AP35, ionomer type) 30 parts-25% polyamide epichlorohydrin solution (WS4020) 10 parts -45 % Modified polyamide resin solution (Smireds resin SPI106N) 10 parts-20% silicic acid dispersion (Mizukasil P527) 50 parts-40% zinc stearate emulsion liquid (Hydrin E-366) 5 parts were mixed with stirring.

Protective layer paint 4
-10% carboxyl modified PVA solution (PVA-KL318) 100 parts-25% polyamide epichlorohydrin solution (WS4020) 10 parts-45% modified polyamide resin solution (Smiledes resin SPI106N) 10 parts-20% silicic acid dispersion ( Mizukasil P527) 50 parts-40% Zinc stearate emulsion liquid (Hydrin E-366) 5 parts were mixed with stirring.

Protective layer paint 5
-10% carboxyl modified PVA solution (PVA-KL318) 70 parts-Aqueous polyurethane resin (Hydran AP40N) 30 parts-45% modified polyamide resin solution (Smireds resin SPI106N) 10 parts-20% silicic acid dispersion (Mizukasil P527) 50 Part-5 parts of 40% zinc stearate emulsion liquid (Hydrin E-366) was stirred and mixed.

Protective layer paint 6
-10% carboxyl-modified PVA solution (PVA-KL318) 70 parts-Aqueous polyurethane resin (Hydran AP40N) 30 parts-25% Polyamide epichlorohydrin solution (WS4020) 10 parts-20% Silicic acid dispersion (Mizukasil P527) 50 parts 5 parts of -40% zinc stearate emulsion liquid (Hydrin E-366) was mixed with stirring.

Protective layer paint 7
-10%% fully saponified PVA solution (Kuraray, PVA-KL318) 50 parts-aqueous polyurethane resin (Hydran AP40N) 50 parts-40% Glyoxal aqueous solution (Mitsui Chemicals) 10 parts-45% modified polyamide resin solution ( Sumirez resin SPI106N) 10 parts-20% silicic acid dispersion (Mizukasil P527) 50 parts-40% zinc stearate emulsion liquid (Hydrin E-366) 5 parts were stirred and mixed.

Protective layer paint 8
-10 %% fully saponified PVA solution (Kuraray, PVA-KL318) 50 parts-40% glyoxal aqueous solution (Mitsui Chemicals) 10 parts-20% silicic acid dispersion (Mizukacil P527) 50 parts-40% zinc stearate 5 parts of an emulsion (hydrin E-366) was mixed with stirring.

[Preparation to thermosensitive recording layer]
60 g / coating amount after drying precoat paint base paper of ^{m 2} was coated with a blade coater so as to be 8.0 g / ^{m 2.} On this, a heat-sensitive color developing layer coating was applied with a blade coater so that the coating amount after drying was 4.5 g / m ² to obtain a heat-sensitive recording paper.

[Example 1]
The protective layer coating 1 was coated on the above heat-sensitive recording paper with a hand-painted bar so that the coating amount after drying was 3.5 g / m ² . After adjusting the humidity in an environment of 23 ° C. and 50%, calendar treatment was performed so that the Beck smoothness was 500 to 1500 seconds, and the heat-sensitive recording material of Example 1 was obtained.
[Example 2]
A heat-sensitive recording material of Example 2 was obtained in the same manner as in Example 1 except that protective layer paint 2 was used in place of protective layer paint 1.
[Example 3]
A thermal recording material of Example 3 was obtained in the same manner as in Example 1 except that the protective layer coating 3 was used instead of the protective layer coating 1.
[Example 4]
A heat-sensitive recording material of Comparative Example 3 was obtained in the same manner as in Example 1 except that the protective layer coating 6 was used instead of the protective layer coating 1.

[Comparative Example 1]
A thermal recording material of Comparative Example 1 was obtained in the same manner as in Example 1 except that the protective layer coating 4 was used in place of the protective layer coating 1.
[Comparative Example 2]
A heat-sensitive recording material of Comparative Example 2 was obtained in the same manner as in Example 1 except that the protective layer paint 5 was used instead of the protective layer paint 1.
[Comparative Example 3]
A thermal recording material of Comparative Example 4 was obtained in the same manner as in Example 1 except that the protective layer coating 7 was used in place of the protective layer coating 1.
[Comparative Example 4]
A thermal recording material of Comparative Example 5 was obtained in the same manner as in Example 1 except that the protective layer coating 8 was used instead of the protective layer coating 1.

The protective layer materials of Examples 1 to 3 and Comparative Examples 1 to 5 are shown in Table 1. In addition, the following evaluation was performed for each sample, and the results are shown in Table 2.

[Print density]
Using a thermal printer TH-PMD (equipped with a thermal head manufactured by Kyocera Corporation) manufactured by Okura Electric Co., Ltd., printing was performed on the prepared thermal recording medium with an applied energy of 0.41 mJ / dot. The printing density of the recording part was measured and evaluated with a Macbeth densitometer RD918. The larger the value, the better the color density.

[Storage performance]
Using a thermal printer TH-PMD (equipped with a thermal head manufactured by Kyocera Corporation) manufactured by Okura Electric Co., Ltd., printing was performed on the created thermal recording medium at an applied energy of 0.41 mJ / dot, and the following storage performance was evaluated. .
From the Macbeth concentration before and after the evaluation, the remaining ratio of the printed portion was calculated by the following calculation method.
Residual rate (%) = (Macbeth concentration after test) / (Macbeth concentration before test) × 100

The heat-resistant heat- sensitive recording material was left in a blow dryer maintained at 80 ° C. for 24 hours, and then the Macbeth density of the printed portion was measured.
○: Residual rate of printed part 75% or more Δ: Residual rate of printed part 50% or more and less than 75% ×: Residual rate of printed part less than 50%

The water-resistant heat-sensitive recording material was immersed in 23 ° C. tap water for 24 hours and air-dried, and then the Macbeth density of the printed portion was measured.
○: Residual rate of printed part 60% or more Δ: Residual rate of printed part 40% or more and less than 60% ×: Residual rate of printed part less than 40%

Plasticizer resistance <br/> paper tube salt Birappu (Hairappu SAS, manufactured by Mitsui Chemicals) Paste A thermosensitive recording medium on which is wound once, what further wound on the salt Birappu in triplicate to the After leaving for 24 hours in an environment of 40 ° C. and 90%, the Macbeth density of the printed part was measured.
○: Residual rate of printed part 15% or more Δ: Residual rate of printed part 10% or more and less than 15% ×: Residual rate of printed part less than 10%

Under a stick-resistant 5 ° C. environment, a solid terminal printer (printer name: HT-180) manufactured by Canon Inc. was used to perform black solid printing of 5 cm in length, and the print samples were visually evaluated.
○: No white spots △: Some white spots occurred ×: Many white spots occurred

  As shown in Table 1, the thermal recording materials of Examples 1 to 4 having an aqueous polyurethane resin and epichlorohydrin-based resin as a protective layer were printed density, heat resistance, water resistance, plasticizer resistance, and stick resistance. It can be seen that the water resistance and the plasticizer resistance of the heat-sensitive recording materials of Examples 1 to 3 in which the polyamine resin is further contained in the protective layer are further improved. On the other hand, in the heat-sensitive recording material of Comparative Example 1 containing no aqueous polyurethane, although the heat resistance, water resistance, and plasticizer resistance are slightly decreased, the print density is greatly decreased. Moreover, Comparative Example 2 and Comparative Example 3 that do not contain epichlorohydrin resin, and Comparative Example 4 that does not contain an aqueous polyurethane resin all exhibit sufficient heat resistance, water resistance, and plasticizer resistance. You can see that it is not.

Claims (4)

In the heat-sensitive recording layer in which a heat-sensitive recording layer and a protective layer containing, as main components, a colorless or light-colored electron-donating leuco dye and an electron-accepting developer are provided in this order on the support, A heat-sensitive recording material comprising a polyurethane resin and an epichlorohydrin-based resin.
The thermosensitive recording material according to claim 1, wherein the protective layer contains a polyamine resin and / or a polyamide resin.
The heat-sensitive recording material according to claim 1 or 2, wherein the aqueous polyurethane resin is a polyurethane ionomer.
The heat-sensitive recording material according to claim 1, wherein the heat-sensitive recording layer contains a carboxyl group-containing resin and / or an epichlorohydrin-based resin.