JP2010162718A - Thermal recording body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a double-sided thermal recording body which has sufficient color developing sensitivity, and has thermal recording bodies at both sides of a substrate, and is suppressed in the stain of a platen roll and the generation of head scum. <P>SOLUTION: In the double-sided thermal recording body having a thermal recording layer comprising a colorless or light-colored electron-donating leuco dye, an electron-accepting developer, and a sensitizer at each of both faces of a substrate, the double-sided thermal recording body is characterized in that the sensitizer is an aliphatic acid amide or an aliphatic acid amide mixture. In particular, an excellent effect is exhibited by using a mixture of stearylamide and palmitamide as the sensitizer, and by using an aliphatic acid amide with a melting point of 90-100°C or the aliphatic acid amide mixture. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a double-sided heat-sensitive recording material utilizing a color development reaction by heat between a colorless or light-colored basic leuco dye and an electron-accepting developer.

In general, a recorded image is obtained by utilizing a color development reaction caused by heat between 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). Thermal recording media are widely used in the fields of facsimiles, computers, and various measuring instruments because of their very vivid color development, no noise during recording, and relatively inexpensive, compact, and easy maintenance. Has been. Recently, in addition to labels and tickets, handheld terminals for outdoor measurement and delivery slips, etc., which are used as output media for various printers and plotters after printing, have rapidly expanded, and the quality of thermal recording media ( There is a need for a double-sided thermal recording material that is environmentally friendly by improving the coloring sensitivity, printing runnability, printing surface strength, etc., and saving resources (reducing dust).

  Conventionally, a double-sided thermal recording paper in consideration of the environment (Patent Document 1) and a thermal printer capable of double-sided thermal recording (Patent Document 2) have been disclosed.

JP-A-9-86041 JP2008-6680

However, a thermal printer capable of double-sided thermal recording (see Patent Document 2) has a structure having two combinations of a thermal head and a platen roll. For this reason, when printing on both sides, about twice as much heat as the total printing on one side is applied to the thermal recording medium, so that the problem of debris adhering to the thermal head tends to occur. In addition, since the surface heated by printing first is further heated in contact with the platen roll when the opposite surface is printed, the platen roll is caused by melting and sublimation of the sensitizer in the heat-sensitive recording layer. Dirt is generated.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a double-sided thermal recording medium having a sufficient color density and suppressing the generation of platen roll stains and head debris.

  As a result of intensive studies, the present inventors have made a double-sided thermal recording medium having a thermal recording layer containing a colorless or light-colored electron-donating leuco dye, an electron-accepting developer and a sensitizer on both sides of the support. The inventors have found that the above-mentioned problems can be solved by using a double-sided thermal recording material characterized in that the sensitizer is a fatty acid amide or a fatty acid amide mixture, and the present invention has been completed.

  According to the present invention, it is possible to obtain a double-sided thermal recording material having sufficient color development sensitivity and suppressing generation of platen roll stains and head debris. In particular, an excellent effect is exhibited in a double-sided thermal recording material having no under layer.

  The double-sided thermal recording material of the present invention is a double-sided thermal recording material having a thermal recording layer containing a colorless or light-colored electron-donating leuco dye, an electron-accepting developer and a sensitizer on both sides of the support, The sensitizer is a fatty acid amide or a fatty acid amide mixture. In particular, the use of a mixture of stearic acid amide and palmitic acid amide as a sensitizer, and the use of a fatty acid amide or a fatty acid amide mixture having a melting point of 90 to 100 ° C. produces an excellent effect. Furthermore, the present invention exhibits an excellent effect in a double-sided thermal recording body in which no under layer, intermediate layer or the like is provided between the support and the thermal recording layer.

  In the present invention, the use of a sensitizer, which is a fatty acid amide exhibiting good stability to heat, suppresses the movement of the sensitizer (fatty acid amide) due to heat applied to the printing in the heat-sensitive recording medium. It is estimated that an excellent effect is exhibited. Therefore, platen roll contamination can be prevented without providing an under layer or a laminate layer.

  In the present invention, the fatty acid amide used for the sensitizer includes lauric acid amide (melting point 86 ° C.), palmitic acid amide (melting point 100 ° C.), stearic acid amide (melting point 109 ° C.), behenic acid amide (melting point) as monoamides. 100 ° C.), saturated fatty acid monoamides such as hydroxystearic acid amide (melting point 110 ° C.), oleic acid amide (melting point 75 ° C.), erucic acid amide (melting point 82 ° C.), ricinoleic acid amide (melting point 65 ° C.), substituted amides N-lauryl lauric acid amide (melting point 77 ° C.), N-palmityl palmitic acid amide (melting point 91 ° C.), N-stearyl stearic acid amide (melting point 94 ° C.), N-oleyl oleic acid amide (melting point 45 ° C.) N-stearyl oleic acid amide (melting point 67 ° C.), N-oleyls Aric acid amide (melting point 74 ° C.), N-stearyl erucic acid amide (melting point 74 ° C.), N-oleyl palmitic acid amide (melting point 69 ° C.), N-12 hydroxystearyl stearic acid amide (melting point 102 ° C.), N-12 Hydroxystearyl oleic acid amide (melting point 90 ° C.), methylol stearate amide (melting point 111 ° C.) as methylol amides, methylol behenic acid amide (melting point 110 ° C.), methylene bis stearic acid amide (melting point 143 ° C.), Methylene bislauric acid amide (melting point 131 ° C.), methylene bishydroxystearic acid amide (melting point 140 ° C.), methylene bisoleic acid amide (melting point 131 ° C.), ethylene biscaprylic acid amide (melting point 165 ° C.), ethylene bis laurin Amide (melting point 157 ° C.), ethylene bis stearic acid amide (melting point 143 ° C.), ethylene bisisostearic acid amide (melting point 100 ° C.), ethylene bishydroxystearic acid amide (melting point 144 ° C.), ethylene bisbehenic acid amide (melting point 141 ° C.) ), Hexamethylene bisbehenic acid amide (melting point 143 ° C.) hexamethylene bis stearic acid amide (melting point 146 ° C.), hexamethylene bishydroxystearic acid amide (melting point 138 ° C.), butylene bishydroxystearic acid amide (melting point 140 ° C.), Saturated fatty acid bisamides such as N, N′-distearyl adipic acid amide (melting point: 144 ° C.), N, N′-distearyl sebacic acid amide (135 ° C.), ethylene bisoleic acid amide (melting point: 118 ° C.), ethylene bis Erucic acid amide (melting point 115 ° C.), hexamethylenebisoleic acid amide (melting point 119 ° C.), N, N′-dioleyl adipic acid amide (melting point 119 ° C.), N, N′-dioleyl sebacic acid amide (melting point 115 C.) unsaturated fatty acid bisamide, m-xylylene bisstearic acid amide (melting point: 123 ° C.), N, N′-dioleyl sebacic acid amide (melting point: 129 ° C.), ethanolamine distearate ( Examples thereof include fatty acid ester amides such as a melting point of 81 ° C., and these can be used alone or in combination of two or more.

  Among these sensitizers, it is desirable to use a mixture of stearic acid amide and palmitic acid amide from the viewpoint of platen roll stain and color development sensitivity. The mixing ratio of stearic acid amide and palmitic acid amide is preferably stearic acid amide: palmitic acid amide = 90: 10 to 50:50 (parts by weight), and preferably 75:25 to 65:35. More preferred.

  In the present invention, the use of a fatty acid amide or a fatty acid amide mixture having a melting point (measured) of 90 to 100 ° C. as the sensitizer also improves the platen roll stain and color development sensitivity. In addition, when using a fatty acid amide mixture, it falls from the weight average from melting | fusing point of each above-mentioned fatty acid amide by a freezing point fall.

  In the present invention, sensitizers that can be used in combination with fatty acid amides include ethylenebisamide, 1,2-di- (3-methylphenoxy) ethane, 1,2-bis (phenoxymethyl) benzene, diphenylsulfone, and p-benzyl. Biphenyl, β-benzyloxynaphthalene, 4-biphenyl-p-tolyl ether, m-terphenyl, 1,2-diphenoxyethane, 4,4′-ethylenedioxy-bis-benzoic acid dibenzyl ester, dibenzoyloxy Methane, 1,2-di (3-methylphenoxy) ethylene, 1,2-diphenoxyethylene, bis [2- (4-methoxy-phenoxy) ethyl] ether, methyl p-nitrobenzoate, dibenzyl oxalate, Di (p-chlorobenzyl) acid, di (p-methylbenzyl) oxalate, diterephthalic acid Benzyl, p-benzyloxybenzoic acid benzyl, di-p-tolyl carbonate, phenyl-α-naphthyl carbonate, 1,4-diethoxynaphthalene, 1-hydroxy-2-naphthoic acid phenyl ester, 4- (m-methylphenoxy) Methyl) biphenyl, orthotoluenesulfonamide, paratoluenesulfonamide and the like can be exemplified, and they can be used alone or in combination of two or more. It is preferable to use it. Further, from the viewpoint of suppressing the occurrence of color development sensitivity, head residue stains, and platen roll stains, the amount of the sensitizer used in combination is preferably 50% by weight or less, more preferably 30%, based on the total solid content of the sensitizer. % By weight or less.

  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-8-59603 Aminobenzenesulfonamide derivatives, bis (4-hydroxyphenylthioethoxy) methane, 1,5-di (4-hydroxyphenylthio) -3-oxapentane, butyl bis (p-hydroxyphenyl) acetate, bis (p -Hydroxyphenyl) methyl 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), described in International Publication No. WO 97/16420 Phenolic compounds such as diphenylsulfone crosslinkable compounds, developer compositions described in International Publication WO02 / 098674, compounds described in International Publication WO02 / 081229 or JP-A No. 2002-301873, 4,4′- Bis 3- (phenoxycarbonylamino) methylphenylureido) diphenylsulfone (trade name: UU manufactured by Asahi Kasei Corporation), thiourea compounds such as N, N′-di-m-chlorophenylthiourea, p-chlorobenzoic acid, stearyl gallate Bis [4- (n-octyloxycarbonylamino) salicylate zinc] 2 Japanese, 4- [2- (p-methoxyphenoxy) ethyloxy] salicylic acid, 4- [3- (p-tolylsulfonyl) propyloxy] salicylic acid, 5- [p- (2-p-methoxyphenoxyethoxy) 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 antipyrine complexes of zinc thiocyanate, terephthalate Examples include complex zinc salts of aldehyde acid and other aromatic carboxylic acid. 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-anilinofluorane; 3-diethylamino-6-chloro-7-p-methylanilinofluorane; 3-diethylamino-6 3-Ethoxyethyl-7-anilinofluorane; 3-diethylamino-7-methylfluorane; 3-diethylamino-7-chlorofluorane; 3-diethylamino-7- (m-trifluoromethylanilino) fluorane; Diethylamino-7- (o-chloroanilino) fluorane; 3-diethyla 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-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 -Trifluoromethylanilino) fluorane; 3-di-n-pentylamino-6-chloro-7-anilinofluorane; 3-di-n-pentyl Mino-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; 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-isoamido) Amino) -6-chloro-7-anilinofluorane; 3- (N-ethyl-N-tetrahydrofurfurylamino) -6-methyl-7-anilinofluorane; 3- (N-ethyl-N-isobutyl) Amino) -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-anilinofluorane; 2 -(4-oxahexyl) -3-dipropylamino-6-methyl-7-anilinofluorane; 2-methyl-6-p- (p-dimethylaminophenyl) aminoani 2-methoxy-6-p- (p-dimethylaminophenyl) aminoanilinofluorane; 2-chloro-3-methyl-6-p- (p-phenylaminophenyl) aminoanilinofluorane; Chloro-6-p- (p-dimethylaminophenyl) aminoanilinofluorane; 2-nitro-6-p- (p-diethylaminophenyl) aminoanilinofluorane; 2-amino-6-p- (p- 2-diethylamino-6-p- (p-diethylaminophenyl) aminoanilinofluorane; 2-phenyl-6-methyl-6-p- (p-phenylaminophenyl) aminoani Linofluorane; 2-benzyl-6-p- (p-phenylaminophenyl) aminoanilinofluorane; 2-hydroxy-6-p- (p-phenylaminophenyl) aminoanilinofluorane; 3-methyl-6-p- (p-dimethylaminophenyl) aminoanilinofluorane; 3-diethylamino-6-p- (P-diethylaminophenyl) aminoanilinofluorane; 3-diethylamino-6-p- (p-dibutylaminophenyl) aminoanilinofluorane; 2,4-dimethyl-6-[(4-dimethylamino) anilino] -Fluoran

<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)- 4-Azaphthalide; 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, and specifically, fully 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, cellulose derivatives such as hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, ethyl cellulose, acetyl cellulose, styrene-maleic anhydride copolymer, styrene-butadiene copolymer, polyvinyl chloride , Polyvinyl acetate, polyacrylamide, polyacrylic acid ester, polyvinyl butyllar, polystyrene and their copolymers, polyamide resin Silicone resins, petroleum resins, terpene resins, ketone resins, and the Khumalo resin. 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.

  Moreover, in this invention, a conventionally well-known lubricant can be used in the range which does not inhibit the desired effect with respect to the said subject. Examples of such lubricants include fatty acid metal salts such as zinc stearate and calcium stearate, waxes, silicon resins and the like. In addition, benzophenone and triazole ultraviolet absorbers, dispersants, antifoaming agents, antioxidants, fluorescent dyes, and the like can be used.

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. From the viewpoint of coating layer strength and printing runnability, it is desirable to use calcium carbonate and silica in combination, and further, calcium carbonate having an average particle diameter of 3 μm or more and an average particle diameter of 5 to 10 μm. It is preferable to use silica having an oil absorption of 150 ml / 100 g or more and a specific surface area of 150 m ² / g or less in combination. When calcium carbonate and silica are used, the weight ratio of calcium carbonate / silica is preferably 20/80 to 80/20, more preferably 40/60 to 60/40. Basic leuco dye 1 About 0.5-10 weight part is preferable with respect to a weight part.

  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 on both surfaces of an arbitrary support such as paper, recycled paper, synthetic paper, film, plastic film, foamed plastic film, and non-woven fabric, the intended double-sided thermal recording material is 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 with a pulverizer such as a ball mill, attritor, 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 a well-known conventional technique. For example, an air knife coater, a rod blade coater, a bill blade coater, a roll coater, a curtain coater, a spray coater, and various other coaters such as a 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 double-sided thermal recording material of the present invention, an undercoat layer such as a polymer material containing a filler can be provided under the thermal recording layer for the purpose of increasing the color development sensitivity. In addition, an overcoat layer can be provided on the heat-sensitive layer in order to add storage stability such as water resistance. Various known techniques in the heat-sensitive recording material field, such as applying a smoothing process such as supercalendering after coating each layer, can be added as necessary.

EXAMPLES The present invention will be specifically described below with reference to examples, but the scope of the present invention is not limited to these examples. In each example, “parts” means “parts by weight” unless otherwise specified.

[Example 1]
<Liquid A: Developer dispersion>
4-hydroxy-4'-isopropoxydiphenylsulfone
(Product name: NY-DS, manufactured by API Corporation) 6.0 parts Polyvinyl alcohol aqueous solution (10% solution) 18.8 parts Water 11.2 parts <Liquid B: Dye dispersion>
3-di-n-butylamino-6-methyl-7-anilinofluorane (manufactured by Yamamoto Kasei Co., Ltd., trade name: ODB-2) 3.0 parts Polyvinyl alcohol aqueous solution (10% solution) 6.9 parts water 3 .9 parts <C liquid: sensitizer dispersion (wax-based material dispersion)>
Stearic acid amide 4.2 parts Palmitic acid amide 1.8 parts Polyvinyl alcohol aqueous solution (10% solution) 18.8 parts Water 11.2 parts The above dispersions are mixed in the proportions shown below to produce a thermal recording layer coating solution. Got. This coating solution is applied and dried on both sides of a support (60 g / m ² base paper) so that the coating amount after drying becomes 6.0 g / m ^2, and the Beck smoothness becomes 200 to 600 seconds with a super calendar. Thus, a double-sided thermal recording material was obtained.

Liquid A 36.0 parts Liquid B 13.8 parts Liquid C 36.0 parts Silica (manufactured by Mizusawa Chemical Co., Ltd., trade name: P537) 25% dispersion 26.0 parts Calcium carbonate (manufactured by Shiraishi Calcium Co., Ltd., trade name: Tunex) E, average particle size: 4.4 μm) 50% dispersion 13.0 parts Zinc stearate (manufactured by Chukyo Yushi Co., Ltd., trade name: Hydrin Z-7-30) 30% dispersion
6.7 parts Polyvinyl alcohol aqueous solution (10% solution)
(Kuraray Co., Ltd., trade name: PVA217, polymerization degree: 1750, saponification degree: 88 mol%)
20.0 parts
[Example 2]
A thermosensitive recording material was obtained in the same manner as in Example 1 except that stearic acid amide and palmitic acid amide in Example 1 were replaced with 6.0 parts of N-palmitylpalmitic acid amide (melting point: 91 ° C.).
[Example 3]
Except that stearic acid amide and palmitic acid amide of Example 1 were replaced with 4.8 parts of lauric acid amide (melting point: 86 ° C.) and 1.2 parts of stearic acid amide (melting point: 109 ° C.), the same as in Example 1. A heat-sensitive recording material was obtained.
[Example 4]
The same procedure as in Example 1 except that stearic acid amide and palmitic acid amide in Example 1 were changed to 2.8 parts and 1.2 parts, respectively, and 2 parts of 1,2-bis (phenoxymethyl) benzene was added. A heat-sensitive recording material was obtained.

[Comparative Example 1]
A heat-sensitive recording material was obtained in the same manner as in Example 1 except that stearic acid amide and palmitic acid amide in Example 1 were changed to 6.0 parts of stearic acid amide.
[Comparative Example 3]
Except that stearic acid amide and palmitic acid amide of Example 1 were replaced with 6.0 parts of 1,2-di- (3-methylphenoxy) ethane (trade name: KS232, manufactured by Sanko Co., Ltd.), the same as Example 1 A heat-sensitive recording material was obtained.
[Comparative Example 4]
A heat-sensitive recording material was obtained in the same manner as in Example 1 except that the stearic acid amide and palmitic acid amide in Example 1 were not used.
The thermosensitive recording materials obtained in the above-described examples and comparative examples were evaluated as follows.
Since the results for both sides were the same, the results for only one side are shown in Table 1.
[Color development sensitivity]
Using TH-PMD manufactured by Okura Electric Co., Ltd., applied energy 0.34
Printing was performed at mJ / dot, 0.25 mJ / dot. The image density after printing and after the quality test was measured with a Macbeth densitometer (RD-914, using an amber filter).
[Printability: Platen roll dirt]
Using Real POS 7198 manufactured by NCR, continuous printing was performed for about 250 m. After leaving for 12 hours, the degree of white stains adhering to the platen roll of the printer was visually judged and evaluated according to the following criteria.

◎: No dirt adherence to platen roll ○: No dirt adherence to platen roll
×: Many stains adhere to the platen roll
[Printability: head residue]
Continuous printing was performed for about 250 m with Real POS 7198 manufactured by NCR, and the head residue and print sample adhering to the thermal head after printing were visually observed.

◯: Slightly attached head residue to thermal head, but no fading of printed part △: Slightly adhered head part of thermal head, but no fading of printed part, but head residue transferred to sample ×: Thermal A large amount of head debris adheres to the head and the printed part is faded [storability: heat resistance]
After pressing on a hot plate at 70 ° C. for 5 seconds, the color density of the background portion was measured with a Macbeth densitometer.

Claims (4)

  In a double-sided thermal recording body having a thermal recording layer containing a colorless or light-colored electron-donating leuco dye, an electron-accepting developer and a sensitizer on both sides of the support, the sensitizer is a fatty acid amide or a fatty acid A double-sided thermal recording material characterized by being an amide mixture. 2. The double-sided thermal recording material according to claim 1, wherein the sensitizer is a mixture of stearic acid amide and palmitic acid amide.   The double-sided thermal recording material according to claim 1 or 2, wherein the fatty acid amide or the fatty acid amide mixture has a melting point of 90 to 100 ° C.   The double-sided thermal recording material according to claim 1, wherein an under layer is not provided between the support and the thermal recording layer.