JP5040942B2 - Thermal recording material - Google Patents

Description

  The present invention relates to a heat-sensitive recording material having high recording sensitivity and extremely low reduction in print density due to heat, humidity, light, and plasticizer.

  The heat-sensitive recording material is a material in which a heat-sensitive recording layer containing a color developing substance, a developer, an adhesive, etc. as a main component is provided on a support generally made of paper, synthetic paper, or a plastic film. A color-recorded image can be obtained by reacting these color-developing substances and the developer with heat energy. Such a thermal recording method has advantages such as that the recording device is compact and inexpensive and easy to maintain, and not only as a recording medium for facsimiles, automatic ticket vending machines, scientific measuring instruments, It is also widely used as an output medium for various printers and plotters for POS labels, CAD and CRT medical images.

  As a combination of a color developing material and a developer used in these heat-sensitive recording layers, a combination of an electron donating dye precursor and an electron accepting material is most widely used. Since it is a reversible reaction, it has the disadvantage of causing a reverse reaction due to the influence of heat, humidity, light, plasticizer, etc., and decoloring. For this reason, it was difficult to apply to documentary evidence that requires preservation. In order to improve such drawbacks, a technique for obtaining a heat-sensitive recording material having a high image storage stability using a leucoin digoid compound is described on a heat-sensitive recording paper (see Patent Document 1), but the color development sensitivity is sufficient. However, there is a problem that the color disappears under extremely severe conditions of heat, humidity, light, plasticizer, and the like.

JP-A-4-124175

  The present invention eliminates the above-mentioned problems associated with conventional heat-sensitive recording materials, and provides a heat-sensitive recording material that has high color-development sensitivity and extremely little reduction in recording density due to heat, humidity, light, and plasticizer.

  The present invention relates to a heat-sensitive recording material in which a heat-sensitive recording layer containing a colorless or light-colored dye precursor compound that can be colored by heating is provided on a support, and the dye precursor compound is represented by the following general formula (1). The present invention relates to a heat-sensitive recording material characterized in that it contains at least one kind of dye precursor compound to be produced, and further contains an oxidizing agent in the heat-sensitive recording layer.

［一般式（１）中、Ｘ及びＹは互いに独立して硫黄原子またはＮＲ₉を表すが、ＸとＹはＮ−Ａ−Ｎの形で結合していてもよい。ここで、Ｒ_９は水素原子、炭素数１〜１０のアルキル基、ＣＯＲ₁₀またはＣＯＯＲ₁₁を表し、Ａは炭素数１〜１０の飽和または不飽和のアルキレン基を表し、Ｒ₁₀およびＲ₁₁は互いに独立して炭素数１〜１２のアルキル基；ベンジル基；ハロゲン原子、炭素数１〜６のアルキル基、炭素数１〜６のアルコキシ基で置換されていてもよいアリール基を表す。ＲおよびＲ’は互いに独立して炭素数４〜１２の第三級アルキル基を表す。また、Ｒ_１〜Ｒ_８は互いに独立して水素原子、ハロゲン原子、炭素数１〜１０のアルキル基、炭素数１〜１０のアルコキシ基、ニトロ基、ＮＲ₁₂Ｒ₁₃またはＳＲ₁₄を表す。ここで、Ｒ₁₂及びＲ₁₃は互いに独立して水素原子；炭素数１〜１２のアルキル基；炭素数４〜１２のシクロアルキル基；ハロゲン原子、炭素数１〜６のアルキル基、炭素数１〜６のアルコキシ基で置換されていてもよいアルアルキル基；ハロゲン原子、炭素数１〜６のアルキル基、炭素数１〜６のアルコキシ基で置換されていてもよいアリール基を表すが、Ｒ₁₂とＲ₁₃は隣接する窒素原子と共にピロリジノ基、ピペリジノ基またはヘキサメチレンイミノ基を形成してもよい。また、Ｒ₁₄は炭素数１〜１０のアルキル基を表す。なお、Ｒ₁とＲ₂、Ｒ₂とＲ₃、Ｒ₃とＲ₄、Ｒ₅とＲ₆、Ｒ₆とＲ₇及びＲ₇とＲ₈は互いに独立してベンゼン環を形成していてもよい。］
前記酸化剤として、有機酸化剤の少なくとも１種を含有することが好ましい。
前記酸化剤として、クロラニル、ブロマニル、１，８−ジクロロアントラキノン、１−クロロアントラキノン、２，５−ジ−ｔｅｒｔ−ブチル−１，４−ベンゾキノン、２，５−ジ−ｔｅｒｔ−アミル−１，４−ベンゾキノン、２，５−ジフェニル−１，４−ベンゾキノン、及び２−ｔｅｒｔ−ブチルアントラキノンから選ばれる少なくとも１種を含有することが好ましい。
前記酸化剤として、２，５−ジ−ｔｅｒｔ−ブチル−１，４−ベンゾキノン、２，５−ジ−ｔｅｒｔ−アミル−１，４−ベンゾキノン、２，５−ジフェニル−１，４−ベンゾキノン、及び２−ｔｅｒｔ−ブチルアントラキノンから選ばれる少なくとも１種を含有することが好ましい。
前記感熱記録層中に、更に酸性物質を含有することが好ましい。
前記酸性物質として、安息香酸亜鉛塩、ｐ−ｔｅｒｔ−ブチル安息香酸亜鉛塩、トリクロル安息香酸亜鉛塩、テレフタル酸亜鉛塩、サリチル酸亜鉛塩、３−ｔｅｒｔ−ブチルサリチル酸亜鉛塩、３−イソプロピルサリチル酸亜鉛塩、３−ベンジルサリチル酸亜鉛塩、３−（α−メチルベンジル）サリチル酸亜鉛塩、３，５−ジ−ｔｅｒｔ−ブチルサリチル酸亜鉛塩、及び３，５−ジ（α−メチルベンジル）サリチル酸亜鉛塩から選ばれる少なくとも１種を含有することが好ましい。
前記染料前駆体化合物として、Ｏ，Ｏ’−ジ（ｔｅｒｔ−ブトキシカルボニル）インジゴホワイト、及びＯ，Ｏ’−ジ（１，１−ジメチルプロポキシカルボニル）インジゴホワイトから選ばれる少なくとも１種を含有することが好ましい。

[In General Formula (1), X and Y independently represent a sulfur atom or NR ₉ , but X and Y may be bonded in the form of N-A-N. Here, R ₉ represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, COR ₁₀ or COOR ₁₁ , A represents a saturated or unsaturated alkylene group having 1 to 10 carbon atoms, and R ₁₀ and R ₁₁ are Independently of each other, it represents an alkyl group having 1 to 12 carbon atoms; a benzyl group; an aryl group optionally substituted by a halogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. R and R ′ each independently represent a tertiary alkyl group having 4 to 12 carbon atoms. R _{1 to} R ₈ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a nitro group, NR ₁₂ R ₁₃ or SR ₁₄ . R ₁₂ and R ₁₃ are each independently a hydrogen atom; an alkyl group having 1 to 12 carbon atoms; a cycloalkyl group having 4 to 12 carbon atoms; a halogen atom, an alkyl group having 1 to 6 carbon atoms; An aralkyl group which may be substituted with an alkoxy group having ˜6; a halogen atom, an alkyl group having 1 to 6 carbon atoms, an aryl group which may be substituted with an alkoxy group having 1 to 6 carbon atoms; ₁₂ and R ₁₃ may form a pyrrolidino group, piperidino group or hexamethyleneimino group together with the adjacent nitrogen atom. R ₁₄ represents an alkyl group having 1 to 10 carbon atoms. R ₁ and R ₂ , R ₂ and R ₃ , R ₃ and R ₄ , R ₅ and R ₆ , R ₆ and R ₇ and R ₇ and R ₈ may form a benzene ring independently of each other. Good. ]
As the oxidizing agent, it is preferable to contain at least one organic oxidizing agent.
Examples of the oxidizing agent include chloranil, bromanyl, 1,8-dichloroanthraquinone, 1-chloroanthraquinone, 2,5-di-tert-butyl-1,4-benzoquinone, 2,5-di-tert-amyl-1,4. It is preferable to contain at least one selected from benzoquinone, 2,5-diphenyl-1,4-benzoquinone, and 2-tert-butylanthraquinone.
As the oxidizing agent, 2,5-di-tert-butyl-1,4-benzoquinone, 2,5-di-tert-amyl-1,4-benzoquinone, 2,5-diphenyl-1,4-benzoquinone, and It is preferable to contain at least one selected from 2-tert-butylanthraquinone.
The heat-sensitive recording layer preferably further contains an acidic substance.
Examples of the acidic substance include zinc benzoate, zinc p-tert-butylbenzoate, zinc trichlorobenzoate, zinc terephthalate, zinc salicylate, zinc 3-tert-butylsalicylate, and zinc 3-isopropylsalicylate. , 3-benzylsalicylic acid zinc salt, 3- (α-methylbenzyl) salicylic acid zinc salt, 3,5-di-tert-butylsalicylic acid zinc salt, and 3,5-di (α-methylbenzyl) salicylic acid zinc salt It is preferable to contain at least one selected from the above.
The dye precursor compound contains at least one selected from O, O′-di (tert-butoxycarbonyl) indigo white and O, O′-di (1,1-dimethylpropoxycarbonyl) indigo white. Is preferred.

  The heat-sensitive recording material of the present invention has a high recording sensitivity and is extremely useful in practical use since it has a very low decrease in print density due to heat, humidity, light, and plasticizer.

  The heat-sensitive recording material of the present invention has a heat-sensitive recording layer containing a dye precursor compound represented by the general formula (1) and an oxidizing agent on a support. When this heat-sensitive recording material is heated, the tertiary alkoxycarboxy group contained in the dye precursor is decarboxylated and decomposed to form a colorless or light-colored indigo white compound, which is followed by heat, humidity, light, plasticizer. It changes to a dark indigo dye showing high fastness. In order to improve the recording sensitivity, it is useful to (I) promote the generation of indigo white by the decomposition of the tertiary alkoxycarboxy group and (II) smoothly advance the subsequent oxidation reaction of indigo white. Therefore, it is presumed that the oxidizing agent of the present invention promotes the oxidation reaction of the indigo white compound, and as a result, the recording sensitivity is improved.

  Further, the acidic substance used in the present invention is considered to have a function of promoting the decomposition of the tertiary alkoxycarboxy group, and has an effect of increasing the recording sensitivity to some extent even in a system without an oxidizing agent, but is combined with an acidic substance and an oxidizing agent. As a result, a significantly high sensitization effect is exhibited. This is considered to be because the acidic substance not only promotes the decomposition reaction of the tertiary alkoxycarboxy group but also enhances the oxidizing ability of the oxidizing agent.

  The dye precursor compound used in the present invention is usually a colorless or light-colored compound, and is a dye precursor compound in which a tertiary alkoxycarboxy group is decomposed by heating to form a colored body. These compounds can be easily synthesized by the methods described in, for example, JP-A-4-124175 and JP-A-2008-201112.

  Specific examples thereof include O, O′-di (tert-butoxycarbonyl) indigo white, O, O′-di (tert-butoxycarbonyl) -5-bromoindigo white, O, O′-di (tert-butoxy). Carbonyl) -5,5′-dibromoindigo white, O, O′-di (tert-butoxycarbonyl) -5,5 ′, 7-tribromoindigo white, O, O′-di (tert-butoxycarbonyl)- 5,5 ′, 7,7′-tetrabromoindigo white, O, O′-di (tert-butoxycarbonyl) -4,4 ′, 5,5 ′, 7,7′-hexabromoindigo white, O, O′-di (tert-butoxycarbonyl) -4,4′-dichloroindigo white, O, O′-di (tert-butoxycarbonyl) -4,4 ′, , 5′-tetrachloroindigo white, O, O′-di (tert-butoxycarbonyl) -5,5′-dimethylindigo white, O, O′-di (tert-butoxycarbonyl) -5,5′-difluoro Indigo white, O, O′-di (tert-butoxycarbonyl) -4,4′-dichloro-5,5′-dibromoindigo white, O, O′-di (tert-butoxycarbonyl) -7,7′- Dimethylindigo white, O, O′-di (tert-butoxycarbonyl) -5,5′-dimethyl-7,7′-dichloroindigowhite, O, O′-di (tert-butoxycarbonyl) -7,7 ′ -Diethylindigo white, O, O'-di (tert-butoxycarbonyl) -6,6'-diethoxyindigo white, O, O ' Di (tert-butoxycarbonyl) -6,6'-dimethoxyindigo white, O, O'-di (tert-butoxycarbonyl) -6,6'-diethylmercaptoindigo white, O, O'-di (tert-butoxy Carbonyl) thioindigo white, O, O′-di (tert-butoxycarbonyl) -6,6′-dichlorothioindigo white, O, O′-di (tert-butoxycarbonyl) -7,7′-dichlorothioindigo White, O, O′-di (tert-butoxycarbonyl) -7,7′-diaminothioindigo white, O, O′-di (tert-butoxycarbonyl) -5,5′-dichloro-7,7′- Diaminothioindigo white, O, O′-di (tert-butoxycarbonyl) -5,5′-dibromo-6 6′-diaminothioindigo white, O, O′-di (tert-butoxycarbonyl) -5,5′-dibromothioindigo white, O, O′-di (tert-butoxycarbonyl) -6,6′-di Ethoxythioindigo white, O, O′-di (tert-butoxycarbonyl) -5,5′-dibromo-6,6′-diethoxythioindigo white, O, O′-di (tert-butoxycarbonyl) -6 , 6'-diethylmercaptothioindigo white, O, O'-di (tert-butoxycarbonyl) -4-methyl-6,6'-dichlorothioindigo white, O, O'-di (tert-butoxycarbonyl)- 4-Methyl-6-chloro-6'-methoxythioindigo white, O, O'-di (tert-butoxycarbonyl) -4 4'-dimethyl-6,6'-dichlorothioindigo white, O, O'-di (tert-butoxycarbonyl) -4,4 ', 7,7'-tetramethyl-5,5'-dichlorothioindigo white O, O ′, N, N′-tetra (tert-butoxycarbonyl) indigo white, O, O ′, N, N′-tetra (tert-butoxycarbonyl) -5-bromoindigo white, O, O ′, N, N′-tetra (tert-butoxycarbonyl) -5,5′-dibromoindigo white, O, O ′, N, N′-tetra (tert-butoxycarbonyl) -5,5 ′, 7-tribromoindigo White, O, O ′, N, N′-tetra (tert-butoxycarbonyl) -5,5 ′, 7,7′-tetrabromoindigo white, O, O ′, N, N -Tetra (tert-butoxycarbonyl) -4,4 ', 5,5', 7,7'-hexabromoindigo white, O, O ', N, N'-tetra (tert-butoxycarbonyl) -4,4 '-Dichloroindigo white, O, O', N, N'-tetra (tert-butoxycarbonyl) -4,4 ', 5,5'-tetrachloroindigo white, O, O', N, N'-tetra (Tert-Butoxycarbonyl) -5,5′-dimethylindigo white, O, O ′, N, N′-tetra (tert-butoxycarbonyl) -5,5′-difluoroindigo white, O, O ′, N, N′-tetra (tert-butoxycarbonyl) -4,4′-dichloro-5,5′-dibromoindigo white, O, O ′, N, N′-tetra (tert-butoxyca) Rubonyl) -7,7′-dimethylindigo white, O, O ′, N, N′-tetra (tert-butoxycarbonyl) -5,5′-dimethyl-7,7′-dichloroindigo white, O, O ′ , N, N′-tetra (tert-butoxycarbonyl) -7,7′-diethylindigo white, O, O ′, N, N′-tetra (tert-butoxycarbonyl) -6,6′-diethoxyindigo white O, O ′, N, N′-tetra (tert-butoxycarbonyl) -6,6′-dimethoxyindigo white, O, O ′, N, N′-tetra (tert-butoxycarbonyl) -6,6 ′ -Diethyl mercapto indigo white etc. are mentioned, However, It is not limited to these. Moreover, 2 or more types of compounds can also be used together as needed.

  The oxidizing agent used in the present invention is considered to have an effect of accelerating the oxidation stage following the production stage of indigo white by decomposition of the tertiary alkoxycarboxy group of the dye precursor compound by heating and increasing the color development sensitivity.

  The oxidizing agent used in the present invention is not particularly limited, but is preferably an organic oxidizing agent because of high recording sensitivity, and examples thereof include triarylmethyl compounds and quinone compounds. Examples of the triarylmethyl compound include triphenylmethyl chloride and triphenylmethyl bromide. As quinone compounds, 2,5-dibromo-1,4-benzoquinone-3,6-dicarboxylic acid-di-n-hexyl ester, 2,5-dichloro-1,4-benzoquinone-3,6-dicarboxylic acid -2,5-dihalogen-1,4-benzoquinone-3,6-dicarboxylic acid esters such as diisobutyl ester, monosulfonylquinones such as 2-p-toluenesulfonyl-1,4-benzoquinone, 2,5-dibenzoyl -1,4-benzoquinone, 1,4-benzoquinone-2,5-dicarboxylic acid dicyclohexyl ester, 2,5-di-tert-butyl-1,4 benzoquinone, 2,5-di-tert-amyl-1,4 Benzoquinone, disubstituted quinones such as 2,5-diphenyl-1,4-benzoquinone, o-chloranil, chloranil, bromanyl, 1, -4-substituted quinones such as ethyl benzoquinone tetracarboxylate, 2,5-di-p-toluenesulfonyl-1,4-benzoquinone-3,6-dicarboxylic acid diisobutyl ester, 2,5-dibutylsulfonyl-1,4- Disulfonylquinone dicarboxylic acid ester such as benzoquinone-3,6-dicarboxylic acid diethyl ester, monosulfonylquinone dicarboxylic acid diester such as 2-p-toluenesulfonyl-1,4-benzoquinone-3,6-dicarboxylic acid dicyclohexyl ester, 1 , 4-naphthoquinone, naphthoquinones such as 2-methyl-1,4-naphthoquinone, 2-tert-butylanthraquinone, 2-anthraquinone carboxylic acid, 1,8-dichloroanthraquinone, anthraquinones such as 1-chloroanthraquinone, etc. It is done. Of course, it is not limited to these, As needed, 1 type, or 2 or more types of compounds can be used together. The amount of the oxidizing agent used is not particularly limited, but the oxidizing agent is preferably used at a ratio of about 1 to 500 parts by mass with respect to 100 parts by mass of the dye precursor compound. In addition, More preferably, it uses in the ratio of about 5-200 mass parts.

  Among them, chloranil, bromanyl, 1,8-dichloroanthraquinone, 1-chloroanthraquinone, 2,5-di-tert-butyl-1,4-benzoquinone, 2,5-di-tert-amyl-1,4-benzoquinone, 2,5-diphenyl-1,4-benzoquinone and 2-tert-butylanthraquinone are preferably used because of their high sensitizing effect. In particular, 2,5-di-tert-butyl-1,4-benzoquinone, 2,5-di-tert-amyl-1,4-benzoquinone, 2,5-diphenyl-1,4-benzoquinone, 2-tert-butyl Anthraquinone is particularly preferably used because of its high light resistance.

  In the present invention, an acidic substance can be further contained in the heat-sensitive recording layer for the purpose of improving the color development sensitivity. The acidic substance is considered to have a function of promoting the decomposition of the tertiary alkoxycarboxy group and increasing the oxidizing ability of the oxidizing agent.

  In the present invention, compounds that can be used as acidic substances include 4-tert-butylphenol, 4-acetylphenol, 4-tert-octylphenol, 4,4′-sec-butylidenediphenol, 4-phenylphenol, 4,4 ′. -Dihydroxydiphenylmethane, 4,4'-isopropylidene diphenol, 4,4'-cyclohexylidene diphenol, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 4,4'-dihydroxydiphenyl sulfide, 4,4′-thiobis (3-methyl-6-tert-butylphenol), 4,4′-dihydroxydiphenylsulfone, 2,4′-dihydroxydiphenylsulfone, 4-hydroxy-4′-isopropoxydiphenylsulfone, and bis (3-ant Phenolic compounds such as -4-hydroxyphenyl) sulfone, 4,4′-bis (p-toluenesulfonylaminocarbonylamino) diphenylmethane, or N- (p-toluenesulfonyl) -N′-phenylurea, and 4-hydroxy Benzophenone, dimethyl 4-hydroxyphthalate, methyl 4-hydroxybenzoate, propyl 4-hydroxybenzoate, 4-hydroxybenzoate-sec-butyl, phenyl 4-hydroxybenzoate, benzyl 4-hydroxybenzoate, 4-hydroxy Phenolic compounds such as tolyl benzoate, chlorophenyl 4-hydroxybenzoate, 4,4′-dihydroxydiphenyl ether, or benzoic acid, p-tert-butylbenzoic acid, trichlorobenzoic acid, terephthalic acid, salicylic acid, 3-ter Fragrances such as -butylsalicylic acid, 3-isopropylsalicylic acid, 3-benzylsalicylic acid, 3- (α-methylbenzyl) salicylic acid, 3,5-di-tert-butylsalicylic acid, 3,5-di (α-methylbenzyl) salicylic acid And organic acidic substances such as salts of aromatic carboxylic acids and these phenolic compounds, aromatic carboxylic acids and polyvalent metals such as zinc, magnesium, aluminum, and calcium.

  In particular, zinc benzoate, zinc p-tert-butylbenzoate, zinc trichlorobenzoate, zinc terephthalate, zinc salicylate, zinc 3-tert-butylsalicylate, zinc 3-isopropylsalicylate, 3- Benzylsalicylic acid zinc salt, 3- (α-methylbenzyl) salicylic acid zinc salt, 3,5-di-tert-butylsalicylic acid zinc salt, 3,5-di (α-methylbenzyl) salicylic acid zinc salt coexist with an oxidizing agent It is preferable because a particularly high sensitizing effect is exhibited.

  In the heat-sensitive recording material of the present invention, the acidic substance is usually preferably used at a rate of about 10 to 500% by mass, more preferably about 30 to 200% by mass, based on the total mass of the dye precursor. Is done. Of course, if necessary, two or more kinds of acidic substances can be used in combination.

  The oxidizing agent and acidic substance used in the present invention can be used by being dissolved in a non-aqueous medium together with a suitable non-water-soluble resin such as an acrylic resin. In this case, preferred non-aqueous media used include xylene, toluene, ethyl acetate, butyl acetate, methyl ethyl ketone, cyclohexanone, methyl cellosolve, butyl cellosolve and the like.

  The thermosensitive recording material of the present invention can be applied to a multicolor thermosensitive recording material that develops colors different from each other. It is also possible to laminate a heat-sensitive recording layer of a color development system different from the heat-sensitive recording layer of the present invention containing the dye precursor compound, and other color development in the heat-sensitive recording layer containing the dye precursor compound. You may have a system thermosensitive recording material. Such other coloring system can be selected from a combination of an electron donating dye precursor and an electron accepting compound used in conventional heat-sensitive recording materials, a combination of a diazo compound and a coupling component, or the like. .

  In the present invention, any of a water-soluble resin, a water-dispersible resin, and a water-insoluble resin can be used as the adhesive contained in the heat-sensitive recording layer. For example, polyvinyl alcohol, starch, modified starch, gum arabic, gelatin, casein, chitosan, methylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, polyvinylpyrrolidone, polyacrylate, polyacrylamide, polyester resin, styrene-acrylate Polymeric resins, water-soluble resins such as styrene-maleic anhydride copolymer resins, methyl vinyl ether-maleic anhydride copolymer resins, isopropylene-maleic anhydride copolymer resins, and polyvinyl acetate, polyacrylate esters, polymethacrylate esters Emulsified dispersions of water-insoluble resins such as polyurethane, polyvinyl chloride, polystyrene butadiene, and polymethyl methacrylate butadiene in aqueous media, and non-aqueous media dissolved in these water-insoluble resins. Rukoto can. Two or more of these adhesives can be used in combination.

  However, it is necessary that such adhesives do not develop color, aggregate or become highly viscous when mixed with the dye precursor compound and each dispersion or solution of the acidic substance or oxidant component. In addition, it is necessary that the formed heat-sensitive recording layer coating is tough. The blending amount of the adhesive in the heat-sensitive recording layer is preferably 5 to 80 parts by weight with respect to 100 parts by weight of the total solid content of the heat-sensitive recording layer. If it exceeds, there is a problem that the recording sensitivity decreases.

  Moreover, in order to improve the water resistance of the thermosensitive recording layer, a crosslinking agent that cures the resin component contained in the thermosensitive recording layer can be used. For example, aldehyde compounds such as glyoxal, polyamine compounds such as polyethyleneimine, epoxy compounds, polyamide resins, melamine resins, dimethylol urea compounds, aziridine compounds, block isocyanate compounds, ammonium persulfate and ferric chloride , And inorganic compounds such as magnesium chloride, sodium tetraborate and potassium tetraborate, or boric acid, boric acid triester, and boron-based polymer are used in the range of about 1 to 10 parts by mass with respect to 100 parts by mass of the total solid content of the thermosensitive recording layer. It is desirable.

  In the present invention, a fine pigment having a high whiteness and an average particle size of 10 μm or less can be used in order to improve the whiteness of the heat-sensitive recording layer and the uniformity of the image. For example, calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcined clay, silica, diatomaceous earth, synthetic aluminum silicate, zinc oxide, titanium oxide, aluminum hydroxide, barium sulfate, surface treated calcium carbonate, silica, etc. Inorganic pigments and organic pigments such as urea-formalin resin, styrene-methacrylic acid copolymer resin, and polystyrene resin can be used. The blending amount of the pigment is preferably 40% by mass or less with respect to the total solid content of the heat-sensitive recording layer in order not to lower the color density.

  In the present invention, various heat-fusible substances can be used. Examples of heat-fusible substances include stearic acid amide, stearic acid bisamide, oleic acid amide, palmitic acid amide, coconut fatty acid amide, behenic acid amide and other fatty acid amides, zinc stearate, calcium stearate, polyethylene wax, carnauba wax , Waxes (or lubricants) such as paraffin wax and ester wax, dimethyl terephthalate, dibutyl terephthalate, dibenzyl terephthalate, dibutyl isophthalate, 1-hydroxynaphthoic acid phenyl ester, oxalic acid dibenzyl ester, oxalic acid Di-p-methylbenzyl ester, oxalic acid di-p-chlorobenzyl ester, 1,2-bis (3-methylphenoxy) ethane, 1,2-diphenoxyethane, 1-phenoxy-2- (4- Tylphenoxy) ethane, diphenyl carbonate, p-benzylbiphenyl, 2,2′-methylenebis (4-methyl-6-tert-butylphenol), 4,4′-butylidenebis (6-tert-butyl-3-methylphenol) ), 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 2,2′-methylenebis (4-ethyl-6-tert-butylphenol), 2, Hindered phenols such as 4-di-t-butyl-3-methylphenol and 4,4′-thiobis (3-methyl-6-t-butylphenol), 2- (2′-hydroxy-) There are sensitizers such as 5'-methylphenyl) -benzotriazole and 2-hydroxy-4-benzyloxybenzophenone, antioxidants and ultraviolet absorbers.

  These heat-fusible substances are preferably contained in the heat-sensitive recording layer generally at a ratio of 400 parts by mass or less with respect to 100 parts by mass of the dye precursor compound. In addition, wetting agents such as acetylene glycol and dialkylsulfosuccinate, as well as pigment dispersants, antifoaming agents, and fluorescent dyes are used as necessary to improve the wettability of the coating solution for the thermosensitive recording layer and eliminate repelling. Can be added.

  The support used in the present invention is prepared by heating and kneading a polyolefin-based resin and a white inorganic pigment, extruding from a die, and stretching in the longitudinal direction. Laminated, stretched in the transverse direction to make translucent or opaque, synthetic paper, and thermoplastic resin such as polyethylene, polypropylene, ethylene-vinyl acetate copolymer resin, polyvinyl chloride, polystyrene, polyester alone or In addition to films obtained by kneading the mixture and extruding it from a die and biaxially stretching, mixing these resins with white inorganic pigments and biaxially stretching opaque films, high quality paper (acidic paper, neutral paper) Those produced from pulp fibers such as medium-quality paper, recycled paper, and coated paper can be used. In order to improve the uniformity of the image, the support made of pulp fibers is preferably provided with a heat-sensitive recording layer after previously providing a coating layer as an undercoat layer. In this case, the sensitivity can be increased by adding an inorganic or organic pigment having a large oil absorption amount or a small apparent specific gravity to the undercoat layer. Further, a conventionally known protective layer can be provided on the heat-sensitive recording layer to improve sticking or wrinkle adhesion to the thermal head.

The coating amount of the heat-sensitive recording layer is generally preferably ² to 15 g / m ^{2 in} terms of color development sensitivity and color density. As the coating method, methods conventionally used by those skilled in the art such as an air knife method, a Mayer bar method, a blade method, a reverse roll method, a slit die method, a multi-slide method, and a curtain coating method can be used. Further, the surface property of the heat-sensitive recording layer can be smoothed with a super calender, gloss calender, machine calender, or the like, so that the surface property can be improved and the recording density and sensitivity can be improved.

  In the present invention, the surface of the support opposite to the heat-sensitive recording layer is provided with a release label process for providing release paper via an adhesive layer, a delayed tack process for providing an adhesive layer that develops adhesiveness by heating, etc. So-called tack processing can also be performed. Furthermore, this back side is used to provide a function as a magnetic recording paper, thermal transfer paper, inkjet paper, xerographic paper, carbonless paper, electrostatic recording paper, and a double-sided recording paper that can be recorded on both front and back sides. You can also. Of course, a double-sided thermal recording material can also be used. As the light source for activating the photoreducing agent in the case of photofixing the heat-sensitive recording material of the present invention, various light sources that emit light of a desired wavelength can be used, for example, fluorescent lamps, xenon lamps, xenon flash lamps. Mercury lamp, photographic flash, strobe, etc.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, the scope of the present invention is not limited by these. Unless otherwise specified, “part” and “%” indicate “part by mass” and “% by mass”, respectively.

Example 1
(Preparation of dye precursor solid dispersion)
A composition comprising 40 parts of O, O′-di (tert-butoxycarbonyl) indigo white, 20 parts of a 10% aqueous solution of sulfone-modified polyvinyl alcohol, and 40 parts of water was prepared using an ultraviscomyl, average particle size of 0.3 μm. The resulting mixture was pulverized to obtain a dye precursor solid dispersion.

(Preparation of oxidant dispersion)
A composition comprising 40 parts of 2,5-di-tert-butyl-1,4-benzoquinone, 20 parts of a 10% aqueous solution of sulfone-modified polyvinyl alcohol, and 40 parts of water is obtained with an ultraviscomyl, average particle size of 0.3 μm. The resulting mixture was pulverized until an oxidant dispersion was obtained.

(Preparation of acidic substance dispersion)
A composition comprising 40 parts of zinc 3,5-di (α-methylbenzyl) salicylate, 20 parts of a 10% aqueous solution of sulfone-modified polyvinyl alcohol, and 40 parts of water has an average particle size of 0.3 μm using Ultraviscomyl. To obtain an acidic substance dispersion.

(Preparation of pigment dispersion)
30 parts of amorphous silica (Mizukasil P527, oil absorption 190 ml / 100 g, manufactured by Mizusawa Chemical Co., Ltd.) was mixed in 120 parts of a 0.7% aqueous solution of sodium polyacrylate, and this mixture was dispersed with a cowless disperser. .

[Creation of thermal recording material]
The above dye precursor solid dispersion, oxidizer dispersion, acidic substance dispersion, pigment dispersion, and 5% aqueous solution of polyvinyl alcohol (trade name: Gohsenol NH-17, manufactured by Nippon Synthetic Chemical Industry) Was mixed and stirred so as to be 30: 15: 15: 20: 20, to obtain a thermal recording layer coating solution. This coating solution was applied onto high-quality paper (basis weight 100 g / m ² ) using a Mayer bar so that the dry weight was 3 g / m ² , thereby producing a heat-sensitive recording material.

Example 2
In the preparation of the oxidant dispersion of Example 1, 2,5-di-tert-amyl-1,4-benzoquinone was used instead of 2,5-di-tert-butyl-1,4-benzoquinone as the oxidant. A thermosensitive recording material was prepared in the same manner as in Example 1 except that it was used.

Example 3
In the preparation of the oxidant dispersion of Example 1, except that 2,5-diphenyl-1,4-benzoquinone was used instead of 2,5-di-tert-butyl-1,4-benzoquinone as the oxidant. A thermosensitive recording material was prepared in the same manner as in Example 1.

Example 4
In the preparation of the oxidant dispersion of Example 1, thermal recording was performed in the same manner as in Example 1 except that chloranil was used instead of 2,5-di-tert-butyl-1,4-benzoquinone as the oxidant. Made the material.

Example 5
In the preparation of the heat-sensitive recording material of Example 1, the dye precursor solid dispersion, the oxidant dispersion, the pigment dispersion, and 5% polyvinyl alcohol (trade name: Gohsenol NH-17) were used without using the acidic substance dispersion. (Manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) A heat-sensitive recording material was prepared in the same manner as in Example 1 except that the aqueous solution was mixed and stirred so that the solid content ratio was 30: 15: 35: 20 to obtain a heat-sensitive recording layer coating solution. It was created.

Example 6
In the preparation of the dye precursor solid dispersion of Example 1, O, O′-di (1,1-dimethylpropoxy) was used instead of O, O′-di (tert-butoxycarbonyl) indigowhite as the dye precursor compound. A heat-sensitive recording material was prepared in the same manner as in Example 1 except that carbonyl) indigo white was used.

Example 7
In preparing the dye precursor solid dispersion of Example 1, O, O ′, N, N′-tetra (tert) instead of O, O′-di (tert-butoxycarbonyl) indigo white as the dye precursor compound. -Butoxycarbonyl) A thermosensitive recording material was prepared in the same manner as in Example 1 except that indigo white was used.

Example 8
In the preparation of the dye precursor solid dispersion of Example 1, O, O′-di (tert-butoxycarbonyl) thio instead of O, O′-di (tert-butoxycarbonyl) indigo white as the dye precursor compound. A heat-sensitive recording material was prepared in the same manner as in Example 1 except that indigo white was used.

Example 9
In the preparation of the acidic substance dispersion liquid of Example 1, this was carried out except that zinc 3,5-di-tert-butylsalicylate was used as the acidic substance instead of zinc 3,5-di (α-methylbenzyl) salicylate. A thermosensitive recording material was prepared in the same manner as in Example 1.

Example 10
In the preparation of the acidic substance dispersion liquid of Example 1, except that 3,5-di (α-methylbenzyl) salicylic acid was used instead of zinc 3,5-di (α-methylbenzyl) salicylate as the acidic substance, A thermosensitive recording material was prepared in the same manner as in Example 1.

Comparative Example 1
In the preparation of the heat-sensitive recording material of Example 5, the dye precursor solid dispersion, the pigment dispersion, and 5% polyvinyl alcohol (trade name: Gohsenol NH-17, Nippon Synthetic Chemical Industry) were used without using the oxidant dispersion. A heat-sensitive recording material was prepared in the same manner as in Example 5 except that the aqueous solution was mixed and stirred so that the solid content ratio was 30:50:20 to obtain a heat-sensitive recording layer coating solution.

Comparative Example 2
In the preparation of the heat-sensitive recording material of Example 1, a dye precursor solid dispersion, an acidic substance dispersion, a pigment dispersion, and 5% polyvinyl alcohol (trade name: Gohsenol NH-17) were used without using an oxidant dispersion. (Manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) A heat-sensitive recording material was prepared in the same manner as in Example 1 except that the aqueous solution was mixed and stirred so that the solid content ratio was 30: 15: 35: 20 to obtain a heat-sensitive recording layer coating solution. It was created.

  The thermosensitive recording material produced by the above method was evaluated as follows, and the results are shown in Table 1.

(Color development)
The thermal recording material was subjected to image recording with an energy of 30 mJ / mm ² by adjusting the applied voltage and pulse width using a thermal head (manufactured by Kyocera Corporation). Model No .: RD-914).
In the color development test, if the color density is 1.00 or higher, there is no problem, and if it is 1.20 or higher, the level is extremely excellent.

(Heat resistant)
The heat-sensitive recording material after image recording, on which the color development was evaluated, was allowed to stand for 100 hours at 60 ° C.-90% RH, and then the density of the colored portion was measured, and the residual ratio (%); Color density density / color density density before heat and humidity test) × 100 was determined.

(Light resistance)
The heat-sensitive recording material after image recording for which the color development was evaluated was allowed to stand in direct sunlight for 200 hours, and then the density of the colored portion was measured, and the residual ratio (%); (the density of the colored portion after the light fastness test / The density of the colored portion before the light resistance test) × 100 was determined.

(Plasticizer resistance)
The heat-sensitive recording material after image recording evaluated for color development was placed on a vinyl chloride film and allowed to stand at 70 ° C. for 200 hours, and then the density of the colored portion was measured, and the residual ratio (%); The density of the colored part after the property test / the density of the colored part before the plasticizer storage stability test) × 100 was determined.

  If the residual rate in heat and humidity resistance, light resistance and plasticizer resistance is 80% or more, it is a satisfactory level, and if it is 90% or more, it is a very excellent level.

Claims (7)

In a heat-sensitive recording material provided with a heat-sensitive recording layer containing a colorless or light-colored dye precursor compound that can be colored by heating on a support, the dye represented by the following general formula (1) as the dye precursor compound A heat-sensitive recording material comprising at least one precursor compound and further containing an oxidizing agent in the heat-sensitive recording layer.

[In General Formula (1), X and Y independently represent a sulfur atom or NR ₉ , but X and Y may be bonded in the form of N-A-N. Here, R ₉ represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, COR ₁₀ or COOR ₁₁ , A represents a saturated or unsaturated alkylene group having 1 to 10 carbon atoms, and R ₁₀ and R ₁₁ are Independently of each other, it represents an alkyl group having 1 to 12 carbon atoms; a benzyl group; an aryl group optionally substituted by a halogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. R and R ′ each independently represent a tertiary alkyl group having 4 to 12 carbon atoms. R _{1 to} R ₈ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a nitro group, NR ₁₂ R ₁₃ or SR ₁₄ . R ₁₂ and R ₁₃ are each independently a hydrogen atom; an alkyl group having 1 to 12 carbon atoms; a cycloalkyl group having 4 to 12 carbon atoms; a halogen atom, an alkyl group having 1 to 6 carbon atoms; An aralkyl group which may be substituted with an alkoxy group having ˜6; a halogen atom, an alkyl group having 1 to 6 carbon atoms, an aryl group which may be substituted with an alkoxy group having 1 to 6 carbon atoms; ₁₂ and R ₁₃ may form a pyrrolidino group, piperidino group or hexamethyleneimino group together with the adjacent nitrogen atom. R ₁₄ represents an alkyl group having 1 to 10 carbon atoms. R ₁ and R ₂ , R ₂ and R ₃ , R ₃ and R ₄ , R ₅ and R ₆ , R ₆ and R ₇ and R ₇ and R ₈ may form a benzene ring independently of each other. Good. ]   The heat-sensitive recording material according to claim 1, comprising at least one organic oxidant as the oxidant.   Examples of the oxidizing agent include chloranil, bromanyl, 1,8-dichloroanthraquinone, 1-chloroanthraquinone, 2,5-di-tert-butyl-1,4-benzoquinone, 2,5-di-tert-amyl-1,4. The heat-sensitive recording material according to claim 1 or 2, comprising at least one selected from -benzoquinone, 2,5-diphenyl-1,4-benzoquinone, and 2-tert-butylanthraquinone.   As the oxidizing agent, 2,5-di-tert-butyl-1,4-benzoquinone, 2,5-di-tert-amyl-1,4-benzoquinone, 2,5-diphenyl-1,4-benzoquinone, and The heat-sensitive recording material according to claim 1 or 2, comprising at least one selected from 2-tert-butylanthraquinone.   The heat-sensitive recording material according to claim 1, further comprising an acidic substance in the heat-sensitive recording layer.   Acidic substances include zinc benzoate, zinc p-tert-butylbenzoate, zinc trichlorobenzoate, zinc terephthalate, zinc salicylate, zinc 3-tert-butylsalicylate, zinc 3-isopropylsalicylate, Selected from 3-benzylsalicylic acid zinc salt, 3- (α-methylbenzyl) salicylic acid zinc salt, 3,5-di-tert-butylsalicylic acid zinc salt, and 3,5-di (α-methylbenzyl) salicylic acid zinc salt The heat-sensitive recording material according to any one of claims 1 to 5, comprising at least one kind.   The dye precursor compound contains at least one selected from O, O'-di (tert-butoxycarbonyl) indigo white and O, O'-di (1,1-dimethylpropoxycarbonyl) indigo white. The heat-sensitive recording material according to any one of 1 to 6.