JP2009292082A - Thermosensitive recording body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermosensitive recording body excellent in recording sensitivity, heat resistance of a skin portion, oil resistance of a recording portion, and excellent in reprinting property after being soaked in water. <P>SOLUTION: The thermosensitive recording body constituted by arranging a thermosensitive recording layer containing a colorless or light-colored basic dye and a color developing agent on a support body contains a specific compound as the color developing agent and further contains oxalic di-p-methylbenzylester, and 1 to 50 mass% of oxalic di-p-chlorbenzylester based on the oxalic di-p-methylbenzylester as a sensitizer in the thermosensitive recording layer and further contains a specific compound and/or 1,5-(3-oxapentamethylene)bis(3-(3-(p-toluenesulfonyl)ureide)benzoate). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a heat-sensitive recording material utilizing a coloring reaction between a colorless or light-colored basic dye and a color former.

  A heat-sensitive recording material is known that utilizes a color reaction between a colorless or light-colored leuco dye and an organic or inorganic colorant so that a recording image is obtained by bringing both coloring materials into contact with each other by heat. Such heat-sensitive recording materials are relatively inexpensive, and the recording equipment is compact and easy to maintain, so that they are used not only as recording media for facsimiles and various computers but also in a wide range of fields.

The fields of use include, for example, cash register paper and ticket paper for POS (point of sales) systems, but with the expansion of the system, the usage environment and usage methods are diversified, increasing use under severe conditions. Have been doing. For this reason, the heat-sensitive recording material is required to have heat resistance, while the printing speed of the printer is increasing year by year, and it is desired that printing can be performed with low printing energy, and conflicting characteristics are required. Furthermore, since it is used as a receipt, it is also necessary for the recording section to have good storage and sealability for oil, water, vinegar, alcohols, plasticizers, office supplies, hand creams, and the like.
In the ticket field, a ticket brought in from a customer may be reprinted at a window.

  It is known that a heat-sensitive recording material provided with a heat-sensitive coloring layer mainly composed of a leuco dye and a colorant on a support has a reversible coloring reaction, so that the color-developing image is decolored with time. . This decolorization is accelerated under exposure, high temperature, and high humidity atmosphere, and further proceeds rapidly by contact or impregnation with water, vinegar, alcohol or wrap, plasticizer contained in the film, oil, etc. Is erased until it cannot be read, or the non-printing portion of the heat-sensitive recording medium develops color, and the contrast between the printing portion and the non-printing portion is lost. In severe cases, reading is impossible. On the other hand, in order to improve the storage stability of recording, a method of providing a protective layer on the thermosensitive coloring layer and a method of adding an epoxy compound to the thermosensitive coloring layer have been proposed. However, a sufficient effect is not obtained. Further, when the protective layer is provided, the sensitivity is deteriorated and the surface absorbability is lowered, so that the sealability is deteriorated. Further, in recent years, development of a colorant having high storage stability has progressed and the above problems are being solved, but there is a drawback that the color development sensitivity is low.

  In addition, there is an attempt to use a phenol trinuclear as a colorant as a colorant or a part of the colorant (see Patent Document 1), but the compatibility between color development sensitivity and storage stability is insufficient. is there. In addition, there is an attempt to improve the sensitivity by reducing the eutectic point to 150 to 200 ° C. by mixing two or more of such phenol trinuclear bodies (see Patent Document 2). A composition containing a phenol trinuclear product obtained by condensing all phenols at the ortho position of the OH group does not provide sufficient sensitivity and storage stability of the recording portion, similar to the colorant disclosed in Patent Document 1. In addition, a novel trinuclear structure in which p-substituted phenol is condensed with other alkylphenols at the para position of the OH group via a methylene group at both ortho positions of the hydroxyl group has been proposed (Patent Document). 3), sufficient sensitivity and storage stability of the recording part are still not obtained. Although it has also been proposed to use a specific phenol trinuclear substance (see Patent Document 4), it has not been possible to obtain a heat-sensitive recording material excellent in storage stability of the recording portion, particularly in oil resistance. is there.

  As described above, in some of the tickets, reprinting is performed on the ticket after sale at the counter, and further information is written. In this way, there is a need for a paper that can be reprinted even when a ticket that has been delivered to a customer is in a severe situation. A combination of oxalic acid di-p-methylbenzyl ester and oxalic acid di-p-chlorobenzyl ester has been proposed as a sensitizer for the purpose of improving heat resistance and sensitivity, but reprintability under harsh conditions There is a problem. (See Patent Documents 5 and 6)

Japanese Patent Laid-Open No. 06-115255 JP 2001-96926 A JP 09-278695 A WO 2005/000597 Publication JP 2004-268261 A JP-A-2005-153310

  An object of the present invention is to provide a heat-sensitive recording material excellent in recording sensitivity, heat resistance of the background portion, oil resistance of the recording portion, and excellent in reprintability after being immersed in water.

  As a result of intensive studies to solve the above problems, the present inventor has soaked in recording sensitivity, heat resistance, oil resistance and water by using a specific phenol trinuclear body and a specific compound in combination in the heat-sensitive recording layer. The present inventors have found that the reprintability after the improvement can be improved, and have further intensively studied to complete the present invention.

  That is, the present invention provides the following thermal recording material.

  Item 1: In a heat-sensitive recording material provided with a heat-sensitive recording layer containing a colorless or light-colored basic dye or a colorant on a support, a compound represented by the following general formula (1) is used as the colorant. Contained,

（式中、Ｒはｎ−ブチル基、ｉｓｏ−ブチル基、ｓｅｃ−ブチル基またはｔｅｒｔ−ブチル基を表す。）
更に、感熱記録層に、増感剤としてシュウ酸ジ−ｐ−メチルベンジルエステルと、シュウ酸ジ−ｐ−メチルベンジルエステルに対してシュウ酸ジ−ｐ−クロルベンジルエステルを１〜５０質量％含有し、更に、下記一般式（２）で示される化合物及び／または１，５−（３−オキサペンタメチレン）ビス（３−（３−（ｐ−トルエンスルホニル）ウレイド）ベンゾエート）を含有させたことを特徴とする感熱記録体。

(In the formula, R represents an n-butyl group, an iso-butyl group, a sec-butyl group, or a tert-butyl group.)
Further, the thermosensitive recording layer contains 1 to 50% by mass of oxalic acid di-p-methylbenzyl ester as a sensitizer and oxalic acid di-p-chlorobenzyl ester to oxalic acid di-p-methylbenzyl ester. In addition, a compound represented by the following general formula (2) and / or 1,5- (3-oxapentamethylene) bis (3- (3- (p-toluenesulfonyl) ureido) benzoate) was included. A heat-sensitive recording material characterized by

（但し、ｎは１〜７の整数を表わす）
項２：前記一般式（２）で示される化合物及び／または１，５−（３−オキサペンタメチレン）ビス（３−（３−（ｐ−トルエンスルホニル）ウレイド）ベンゾエート）を呈色剤に対して３〜１００質量％含有する、項１に記載の感熱記録体。
項３：支持体と感熱記録層との間に、下塗り層を設け、前記下塗り層が２層であり、第一下塗り層と第二下塗り層とが同一の下塗り層用塗液からなり、前記第一下塗り層と第二下塗り層との乾燥後の塗工量の割合が２：８〜８：２である、項１または２に記載の感熱記録体。

(Where n represents an integer of 1 to 7)
Item 2: The compound represented by the general formula (2) and / or 1,5- (3-oxapentamethylene) bis (3- (3- (p-toluenesulfonyl) ureido) benzoate) with respect to the colorant Item 2. The heat-sensitive recording material according to Item 1, which is contained in an amount of 3 to 100% by mass.
Item 3: An undercoat layer is provided between the support and the thermosensitive recording layer, the undercoat layer is two layers, and the first undercoat layer and the second undercoat layer are composed of the same undercoat layer coating solution, Item 3. The thermal recording material according to Item 1 or 2, wherein the ratio of the coating amount after drying of the first undercoat layer and the second undercoat layer is from 2: 8 to 8: 2.

  The heat-sensitive recording material of the present invention has an effect excellent in recording sensitivity, heat resistance of the background portion, oil resistance of the recording portion, and reprintability after being immersed in water.

  Hereinafter, the present invention will be described in more detail.

  As a colorant in the heat-sensitive recording layer,

（式中、Ｒはｎ−ブチル基、ｉｓｏ−ブチル基、ｓｅｃ−ブチル基またはｔｅｒｔ−ブチル基を表す。）
を使用することで、記録感度に優れた感熱記録体は得られるが、一方で、記録部の耐油性が劣っていた。

(In the formula, R represents an n-butyl group, an iso-butyl group, a sec-butyl group, or a tert-butyl group.)
Is used, a thermosensitive recording material excellent in recording sensitivity can be obtained, but on the other hand, the oil resistance of the recording portion is inferior.

  In the present invention, in the heat-sensitive recording layer, oxalic acid di-p-methylbenzyl ester is further added as a sensitizer, and oxalic acid di-p-methylbenzyl ester is mixed with 1 to 1 oxalic acid di-p-chlorobenzyl ester. The compound represented by the following general formula (2) and / or 1,5- (3-oxapentamethylene) bis (3- (3- (p-toluenesulfonyl) ureido) benzoate) It has been found that a heat-sensitive recording material excellent in recording sensitivity, heat resistance of the background portion, oil resistance of the recording portion and reprintability after being immersed in water can be obtained.

（但し、ｎは１〜７の整数を表わす）

(Where n represents an integer of 1 to 7)

The color former represented by the general formula (1) can be obtained by the synthesis method described in WO 2005/000597.
For example, it is preferable to condense a p-substituted phenol derivative represented by the following general formula (3) and at least one of the phenolic compounds represented by the following general formula (4).

The p-substituted phenol derivative represented by the general formula (3) is obtained by dihydroxymethylating a corresponding p-substituted phenol, wherein R _d is an n-butyl group, an iso-butyl group, or a sec-butyl group. , Tert-butyl group, preferably sec-butyl group, tert-butyl group. R _e is a group selected from the group consisting of hydrogen, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and a halogen atom, and R _e may be the same as or different from each other. Of these, hydrogen or a methyl group is preferable.

Such as, for example, 2,6-dihydroxymethyl-4-butylphenol,
Examples include 2,6-dihydroxymethyl-4-isobutylphenol, 2,6-dihydroxymethyl-4-tert-butylphenol, 2,6-dihydroxymethyl-4-sec-butylphenol.

  Dihydroxymethylation of these p-substituted phenols can be carried out by a conventional method. For example, p-substituted phenol and formaldehyde are reacted in the presence of water and a basic catalyst, and the reactive organism is reacted with an acid. It can be obtained by neutralization or acidification.

On the other hand, the phenolic compound to be condensed with the p-substituted phenol derivative is represented by the general formula (4), and an unsubstituted phenol in which R _f is a hydrogen atom is preferable.

  Using the p-substituted phenol derivative and the phenolic compound, a colorant used in the present invention can be prepared according to a conventionally known method. For example, when a predetermined amount of the above p-substituted phenol derivative and a phenolic compound are heated and reacted in the presence of an appropriate acid catalyst, condensation of both occurs, and a phenol trinuclear compound represented by the general formula (1) is obtained. It is done. This is because, in this condensation reaction, generally, the phenolic compound has a high reaction activity at the para-position and the ortho-position with respect to the OH group represented by the formula (4).

  The condensation product thus obtained can be used as a colorant as it is, but in particular, when the purity of the colorant is required, a general purification method, if necessary, For example, the condensation product is once dissolved in a good solvent, then added to a poor solvent and reprecipitated. Alternatively, the product may be washed with a solvent in which other condensate is dissolved, and further purified by heating and dissolving the product in a solvent, followed by cooling and recrystallization, and then used as a colorant.

Examples of the colorant represented by the general formula (1) used in the present invention include 2,6-bis [(4-hydroxyphenyl) methyl] -4- (sec-butyl) phenol, 2,6. -Bis [(4-hydroxyphenyl) methyl] -4- (tert-butyl) phenol, 2,6-bis [(4-hydroxyphenyl) methyl] -4- (n-butyl) phenol, 2,6-bis [(4-Hydroxyphenyl) methyl] -4- (iso-butyl) phenol, 2,-[(4-hydroxyphenyl) methyl] -6- (2-hydroxyphenyl) methyl] -4- (sec-butyl) Phenol, 2,-[(4-hydroxyphenyl) methyl] -6- (2-hydroxyphenyl) methyl] -4- (tert-butyl) phenol, 2,-[(4-hydroxyphenyl) methyl] -6 (2-hydroxy Phenyl) methyl] -4- (n-butyl) phenol and 2,-[(4-hydroxyphenyl) methyl] -6- (2-hydroxyphenyl) methyl] -4- (iso-butyl) phenol.

  The ratio of the compound represented by the general formula (1) used in the present invention in the heat-sensitive recording layer is appropriately selected according to the basic dye to be used, and is not particularly limited. Generally, it is about 50 to 500 parts by mass, preferably about 100 to 350 parts by mass with respect to 100 parts by mass of the basic dye. If it is the range of 50-500 mass parts, the heat-sensitive recording material excellent in recording sensitivity will be obtained.

  Examples of the sensitizer used in the heat-sensitive recording layer of the present invention include oxalic acid di-p-methylbenzyl ester and oxalic acid di-p-chlorobenzyl ester, and oxalic acid di-p-methylbenzyl ester. By blending 1 to 50 parts by mass of oxalic acid di-p-chlorobenzyl ester with 100 parts by mass of ester, the heat sensitivity of the background part, which is an effect, is excellent in reprintability after being immersed in water. A recording medium is obtained. As a compounding quantity, 3-40 mass parts is preferable, and 3-35 mass parts is more preferable.

  Furthermore, the following sensitizers may be added to the heat-sensitive recording layer of the present invention to such an extent that the effects are not impaired. For example, stearic acid amide, methoxycarbonyl-N-stearic acid benzamyl, N-benzoyl stearic acid amide, N-eicosanoic acid amide, ethylene bis stearic acid amide, behenic acid amide, methylene bis stearic acid amide, N-methylol stearic acid amide, Dibenzyl terephthalate, dimethyl terephthalate, dioctyl terephthalate, benzyl p-benzyloxybenzoate, phenyl 1-hydroxy-2-naphthoate, 2-naphthylbenzyl ether, m-terphenyl, p-benzylbiphenyl, p-tolylbiphenyl Ether, di (p-methoxyphenoxyethyl) ether, 1,2-di (3-methylphenoxy) ethane, 1,2-di (4-methylphenoxy) ethane, 1,2-di (4-methoxyphenoxy) ethane 1,2-di (4-chlorophenoxy) ethane, 1,2-diphenoxyethane, 1- (4-methoxyphenoxy) -2- (3-methylphenoxy) ethane, p-methylthiophenylbenzyl ether, 1, 4-di (phenylthio) butane, p-acetotoluizide, p-acetophenetide, N-acetoacetyl-p-toluidine, di (β-biphenylethoxy) benzene, p-di (vinyloxyethoxy) benzene, 1-isopropyl Examples thereof include phenyl-2-phenylethane.

  The use ratio of the sensitizer in the heat-sensitive recording layer is appropriately selected according to the basic dye to be used and is not particularly limited, but is generally 5 to 500 with respect to 100 parts by mass of the basic dye. The amount is about 10 parts by mass, preferably about 10 to 350 parts by mass. If it is in the range of 5 to 500 parts by mass, both the heat resistance of the recording part and the recording sensitivity can be achieved.

  Further, a compound represented by the following general formula (2) and / or 1,5- (3-oxapentamethylene) bis (3- (3- (p-toluenesulfonyl) ureido) benzoate) contained in the heat-sensitive recording layer The use ratio is about 3 to 100 parts by mass, and more preferably about 20 to 80 parts by mass with respect to 100 parts by mass of the compound represented by the general formula (1). If it is less than 3 masses, it is inferior to oil resistance, and when it exceeds 100 mass parts, there exists a possibility that a sensitivity may fall.

（但し、ｎは１〜７の整数を表わす）

(Where n represents an integer of 1 to 7)

  1,5- (3-Oxapentamethylene) bis (3- (3- (p-toluenesulfonyl) ureido) benzoate) is synthesized, for example, by the method described in the Examples of Japanese Patent Application No. 2004-242569. be able to.

(1) Synthesis of raw material 1,5- (3-oxapentamethylene) bis (3-aminobenzoate) In a three-necked flask equipped with a thermometer, a reflux tube and a dropping funnel, 9.84 g of 3-aminobenzoic acid and 120 ml Of N, N-dimethylformamide (dehydrated) and 9.96 g of potassium carbonate (anhydrous) are added to the solution. While stirring this mixture with a magnetic stirrer, 5.16 g of bis (2-chloroethyl) ether was added at room temperature. The reaction suspension was stirred at room temperature, heated to reflux at 130 ° C. for 4 hours, cooled to room temperature, added to 300 ml of water, and vigorously stirred to precipitate a white solid. By filtering the aqueous suspension, 10.5 g of 1,5- (3-oxapentamethylene) bis (3-aminobenzoate) white solid was obtained.
The obtained white solid was confirmed to be the target product by various instrumental analyses.

(2) Synthesis of 1,5- (3-oxapentamethylene) bis (3- (3- (p-toluenesulfonyl) ureido) benzoate) In a three-necked flask equipped with a dropping funnel, a thermometer and a reflux condenser, 5 g of 1,5- (3-oxapentamethylene) bis (3-aminobenzoate) was added, and 200 ml of acetonitrile was added thereto and stirred to dissolve. While stirring this mixed solution with a magnetic stirrer, 13.8 g of p-toluenesulfonyl isocyanate was added dropwise at room temperature from a dropping funnel. As the reaction mixture continued to stir, a large amount of white solid precipitated. The reaction mixture was heated at 80 ° C. for 4 hours, cooled and filtered to give 19.5 g of white crystals.

The analysis value of this white crystal is as follows.
Melting point (from DSC): 139.8 ° C
Results of NMR measurement (in DMSO) (numbers are in ppm)
δ = 2.36 (s, 6H), 3.77 (t, 4H), 4.36 (t, 4H), 7.32 (t, 2H), 7.41 (d, 4H), 7.52 -7.54 (m, 4H), 7.83 (d, 4H), 7.98 (t, 2H)
In addition, a peak that may be attributed to NH appeared near δ = 9.07, 10.85.

As the colorless or light-colored basic dye used for the heat-sensitive recording layer, various known dyes can be used. Specifically, for example, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide Blue coloring dyes such as 3- (4-diethylamino-2-methylphenyl) -3- (4-dimethylaminophenyl) -6-dimethylaminophthalide and fluorane, 3- (N-ethyl-Np- Tolyl) amino-7-N-methylanilinofluorane, 3-diethylamino-7-anilinofluorane, 3-diethylamino-7-dibenzylaminofluorane, etc., green coloring dye, 3,6-bis (diethylamino) ) Fluorane-γ-anilinolactam, 3-cyclohexylamino-6-chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluora Red coloring dyes such as 3-diethylamino-7-chlorofluorane, 3- (N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluorane, 3- (N-methyl-N- (Cyclohexyl) amino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-di (n-butyl) amino-6-methyl-7-anilinofluorane 3-di (n-pentyl) amino-6-methyl-7-anilinofluorane, 3-diethylamino-7- (o-chlorophenylamino) fluorane, 3- (N-ethyl-p-toluidino) -6 Methyl-7-anilinofluorane, 3- (N-ethyl-p-toluidino) -6-methyl-7- (p-toluidino) fluorane, 3- (N-ethyl-N-tetrahydrofluorine) Ruamino) -6-methyl-7-anilinofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3-dimethylamino-6-methyl-7-anilinofluorane, 3-pyrrolidino-6 -Methyl-7-anilinofluorane, 3-piperidino-6-methyl-7-anilinofluorane, 2,2-bis {4- [6 '-(N-cyclohexyl-N-methylamino) -3' Black coloring dyes such as methyl spiro [phthalide-3,9′-xanthen-2′-ylamino] phenyl] propane, 3-diethylamino-7- (3′-trifluoromethylphenyl) aminofluorane, 3,3- Bis [1- (4-methoxyphenyl) -1- (4-dimethylaminophenyl) ethylene-2-yl] -4,5,6,7-tetrachlorophthalide, 3,3-bis [1- 4-methoxyphenyl) -1- (4-pyrrolidinophenyl) ethylene-2-yl] -4,5,6,7-tetrachlorophthalide, 3-p- (p-dimethylaminoanilino) anilino-6 -Methyl-7-chlorofluorane, 3-p- (p-chloroanilino) anilino-6-methyl-7-chlorofluorane, 3,6-bis (dimethylamino) fluorene-9-spiro-3 '-(6 Dye etc. having an absorption wavelength in the near infrared region such as' -dimethylamino) phthalide. Of course, it is not limited to these, Moreover, 2 or more types can also be used together as needed.
In particular, a compound having a melting point of 200 ° C. or more is preferable from the viewpoint of heat resistance, and in particular, 3- (N-ethyl-p-toluidino) -6-methyl-7-arininofluorane, 3- (N-ethyl-p-toluidino). ) -6-methyl-7- (p-toluidino) fluorane and 3-diethylamino-7- (o-chloroanilino) fluorane are preferred.

The colorant used in combination with the basic dye as described above is a specific colorant of the invention of the present application, but various known materials such as activated clay, attapulgite, colloidal silica, and the like within a range that does not hinder. Inorganic acidic substances such as aluminum silicate, 4,4′-isopropylidenediphenol, 1,1-bis (4-hydroxyphenyl) cyclohexane, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 2, 4′-dihydroxydiphenylsulfone, 4,4′-bis [(4-methyl-3-phenoxycarbonylaminophenyl) ureido] diphenylsulfone, Np-toluenesulfonyl-N′-3- (p-toluenesulfonyloxy) Phenylurea, 4,4′-dihydroxydiphenyl sulfide, hydroquinone monobenzyl ether, 4 -Benzyl hydroxybenzoate, 4,4'-dihydroxydiphenylsulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, 4-hydroxy-4'-methyldiphenylsulfone Phenolic compounds such as 4-hydroxyphenyl-4′-benzyloxyphenylsulfone, 3,4-dihydroxyphenyl-4′-methylphenylsulfone, thiourea compounds such as N, N′-di-m-chlorophenylthiourea, N- (p-toluenesulfonyl) carbamoyl acid p-cumylphenyl ester, N- (p-toluenesulfonyl) carbamoyl acid p-benzyloxyphenyl ester, N- (o-toluoyl) -p-toluenesulfoamide, N- (P-Toluenesulfonyl) -N ′-( p-Tolyl) Urea and other molecules having —SO ₂ NH— bond, p-chlorobenzoic acid, 4- [2- (p-methoxyphenoxy) ethyloxy] salicylic acid, 4- [3- (p-tolyl) Sulfonyl) propyloxy] salicylic acid, 5- [p- (2-p-methoxyphenoxyethoxy) cumyl] salicylic acid and the like, and zinc, magnesium, aluminum, calcium, titanium, manganese of these aromatic carboxylic acids, A salt with a polyvalent metal such as tin or nickel, an organic acid substance such as an antipyrine complex of zinc thiocyanate, or a complex zinc salt of terephthalaldehyde acid and other aromatic carboxylic acid can be used in combination.

  In the heat-sensitive recording layer of the present invention, a storability improving agent may be further added. For example, 2,2′-methylenebis (4-methyl-6-tert-butylphenol), 2,2′-methylenebis (4 -Ethyl-6-tert-butylphenol), 2,2'-ethylidenebis (4,6-di-tert-butylphenol), 4,4'-thiobis (2-methyl-6-tert-butylphenol), 4,4 '-Butylidenebis (6-tert-butyl-m-cresol), 1- [α-methyl-α- (4'-hydroxyphenyl) ethyl] -4- [α', α'-bis (4'-hydroxyphenyl) ) Ethyl] benzene, 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, 1,1,3-tris (2-methyl-4-hydroxy-) -Tert-butylphenyl) butane, 4,4'-thiobis (3-methylphenol), 4,4'-dihydroxy-3,3 ', 5,5'-tetrabromodiphenylsulfone, 4,4'-dihydroxy- 3,3 ′, 5,5′-tetramethyldiphenylsulfone, 2,2-bis (4-hydroxy-3,5-dibromophenyl) propane, 2,2-bis (4-hydroxy-3,5-dichlorophenyl) Hindered phenol compounds such as propane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, 1,4-diglycidyloxybenzene, 4,4′-diglycidyloxydiphenylsulfone, 4-benzyl Oxy-4 '-(2-methylglycidyloxy) diphenylsulfone, diglycidyl terephthalate, cresol novolak Type epoxy resin, phenol novolac type epoxy resin, epoxy compound such as bisphenol A type epoxy resin, N, N′-di-2-naphthyl-p-phenylenediamine, 2,2′-methylenebis (4,6-di-tert) -Butylphenyl) phosphate sodium or polyvalent metal salt, bis (4-ethyleneiminocarbonylaminophenyl) methane and the like.

  The coating solution for the heat-sensitive recording layer containing these substances generally uses water as a dispersion medium, and dyes, colorants, specific compounds used in the present invention, and sensitizers by agitating and pulverizing machines such as a ball mill, an attritor, and a sand mill. Etc. are prepared by blending materials obtained by dispersing them together or separately.

  In the heat-sensitive recording layer coating liquid, starch, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, carboxy-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol , Diisobutylene / maleic anhydride copolymer salt, styrene / maleic anhydride copolymer salt, ethylene / acrylic acid copolymer salt, styrene / acrylic acid copolymer salt, styrene / butadiene copolymer emulsion, urea resin At least one of melamine resin, amide resin, polyurethane resin and the like is blended in the range of about 5 to 50% by mass with respect to the total solid content of the heat-sensitive recording layer.

  In addition, various auxiliary agents can be added to the heat-sensitive recording layer coating liquid as necessary. For example, sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate, fatty acid metal salt, etc. Agents, zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, ester wax, and other waxes, antifoaming agents, coloring dyes, pigments, and the like are appropriately added. Examples of the pigment include inorganic pigments such as kaolin, clay, calcium carbonate, calcined clay, calcined kaolin, titanium oxide, aluminum hydroxide, diatomaceous earth, particulate anhydrous silica, activated clay, styrene microballs, nylon powder, polyethylene powder, urea. -Organic pigments such as formalin resin filler and raw starch particles.

According to the present invention, if necessary, an undercoat layer can be provided between the support and the thermosensitive recording layer in order to further improve the recording sensitivity and the recording runnability.
The undercoat layer has an oil absorption amount of 70 ml / 100 g or more, particularly at least one selected from the group consisting of oil-absorbing pigments, organic hollow particles, and thermally expandable particles having a viscosity of about 80 to 150 ml / 100 g, and an adhesive as a main component. The undercoat layer coating solution is formed by applying and drying on a support. Here, the oil absorption is a value determined according to the method of JIS K 5101-1991.

  Various types of oil-absorbing pigments can be used. Specific examples include inorganic pigments such as calcined clay, calcined kaolin, amorphous silica, and talc. The average particle diameter of these oil-absorbing pigments (50% value by laser diffraction type particle size distribution measuring device (trade name: SALD2000, manufactured by Shimadzu Corporation)) is about 0.01 to 5 μm, particularly about 0.02 to 3 μm. Is preferred.

  The amount of the oil-absorbing pigment used can be selected from a wide range, but generally it is preferably from 2 to 95% by mass, particularly from about 5 to 90% by mass, based on the total solid content of the undercoat layer.

  Moreover, as an organic hollow particle, a conventionally well-known thing, for example, the particle | grains whose hollow rate consists of an acrylic resin, a styrene resin, a vinylidene chloride resin etc. about 50-99% can be illustrated. Here, the hollowness is a value obtained by (d / D) × 100. In the formula, d represents the inner diameter of the organic hollow particles, and D represents the outer diameter of the organic hollow particles. The average particle diameter of the organic hollow particles (50% value by a laser diffraction particle size distribution measuring device (trade name: SALD2000, manufactured by Shimadzu Corporation)) is preferably about 0.5 to 10 μm, particularly preferably about 1 to 3 μm.

  The amount of the organic hollow particles used can be selected from a wide range, but generally it is preferably from 2 to 90% by mass, particularly from about 5 to 70% by mass, based on the total solid content of the undercoat layer.

  When the oil-absorbing inorganic pigment is used in combination with the organic hollow particles, the oil-absorbing inorganic pigment and the organic hollow particles are used within the above-mentioned usage amount range, and the total amount of the oil-absorbing inorganic pigment and the organic hollow particles is the entire undercoat layer. It is preferable that it is 5-90 mass% with respect to solid content, especially about 10-80 mass%.

  Various types of thermally expandable particles can be used. Specific examples include thermally expandable fine particles obtained by microencapsulating low-boiling hydrocarbons with a copolymer such as vinylidene chloride and acrylonitrile by an in situ polymerization method. Can be given. Examples of the low boiling point hydrocarbon include ethane and propane.

  The amount of the thermally expandable particles can be selected from a wide range, but is generally about 1 to 80% by mass, particularly preferably about 10 to 70% by mass, based on the total solid content of the undercoat layer.

  As the adhesive, an adhesive used for the heat-sensitive recording layer can be appropriately used, and starch-vinyl acetate graft copolymer, various polyvinyl alcohols, and styrene / butadiene copolymer latex are particularly preferable.

  Examples of the various polyvinyl alcohols include fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, diacetone-modified polyvinyl alcohol, and silicon-modified polyvinyl alcohol.

  Although the usage-amount of the said adhesive agent can be selected in a wide range, generally it is about 5-30 mass% with respect to the undercoat layer total solid, and it is especially preferable that it is about 10-25 mass%.

  In addition, as auxiliary agents, known agents such as lubricants, antifoaming agents, wetting agents, preservatives, fluorescent brighteners, dispersants, thickeners, colorants, antistatic agents, and crosslinking agents can be used.

  The method for applying the coating solution for the undercoat layer is not particularly limited. For example, conventionally known methods such as air knife coating, varibar blade coating, pure blade coating, gravure coating, rod blade coating, short dwell coating, curtain coating, and die coating are known. Any of these coating methods can be employed.

  In the heat-sensitive recording material of the present invention, a protective layer is provided on the recording layer for the purpose of improving the storage stability of the recorded image with respect to chemicals such as plasticizers and oils, or the recording suitability. There is no particular limitation, and water is generally used as a dispersion medium, and starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, carboxy-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, silicon-modified polyvinyl It is prepared by mixing and stirring a binder such as alcohol and a pigment such as kaolin, light calcium carbonate, and fine particle silica.

  Furthermore, in the coating liquid for the protective layer, surfactants such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, ester wax, and surfactants such as sodium dioctylsulfosuccinate (dispersant, wetting) Agent), an antifoaming agent, and various auxiliary agents such as water-soluble polyvalent metal salts such as potassium alum and aluminum acetate can be appropriately added. In order to further improve the water resistance, a curing agent such as glyoxal, boric acid, dialdehyde starch, and epoxy compound can be used in combination.

  In particular, microcapsules encapsulating a UV absorber that is liquid at room temperature, such as 2- (2′-hydroxy-3′-dodecyl-5′-methylphenyl) benzotriazole, in the protective layer are adjusted to the total solid content of the protective layer. On the other hand, when the ultraviolet absorber is added so as to be 10 to 40% by mass, yellowing of the background portion and fading of the recorded image are remarkably improved with respect to light exposure.

  The method for forming the undercoat layer, the heat-sensitive recording layer and the protective layer is not particularly limited. For example, an appropriate method such as air knife coating, varibar blade coating, pure blade coating, rod blade coating, short dwell coating, curtain coating, die coating, etc. The undercoat layer coating solution is applied and dried on the support by the coating method, and then the thermal recording layer coating solution and the protective layer coating solution are applied and dried on the undercoat layer. In addition, as a support body, it selects suitably from paper, a plastic film, a synthetic paper, a nonwoven fabric, a metal vapor deposition, etc., and is used.

The coating amount of the undercoat layer is not particularly limited. In the case of two undercoat layers, the thickness of the undercoat layer is 3 to 12 μm (preferably 5 to 10 μm), and the total thickness of the undercoat layer is 6 to 30 μm (preferably May be appropriately adjusted so as to be 10 to 20 μm). The coating amount after drying per layer is about 1 to 15 g / m ² (preferably 2.5 to 10 g / m ² , and the total coating amount of the undercoat layer is about ² to 35 g / m ² . Yes, more preferably 7 to 20 g / m ²

  By making the undercoat layer into a multilayer of two layers, the effect of improving the heat resistance can be obtained in the heat-sensitive recording material. By providing two or more undercoat layers, the sensitivity and image quality can be greatly improved, but there is also an effect of suppressing the penetration of the thermal paint at the time of coating, which can be expected to further improve the strength of the thermal recording medium. .

The coating amount of the heat-sensitive recording layer coating composition is 2~12g / ^{m 2} in dry weight, preferably 3 to 10 g / ^{m 2} approximately, the coating amount of the protective layer coating liquid for a dry weight 0.5 to 15 g / ^{m 2} Preferably, it is adjusted in the range of about 1.0 to 8 g / m ² .

  If necessary, a protective layer can also be provided on the back side of the heat-sensitive recording material to further improve the storage stability or give it a high gloss. Applying a smoothing process such as supercalendering after smearing each layer, or applying adhesive treatment to the back of the recording material to process an adhesive label, providing a magnetic recording layer, a coating layer for printing, and a thermal transfer recording layer, etc. Various known techniques in the heat-sensitive recording material manufacturing field can be added as necessary.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples. In the examples, “parts” and “%” represent “parts by mass” and “mass%”, respectively, unless otherwise specified.

Example 1
Preparation of coating solution for undercoat layer 40 parts of calcined clay (trade name: Ansilex, oil absorption 110 ml / 100 g, manufactured by EC), organic hollow particles having an average particle size of 1.0 μm (inner diameter / outer diameter: 0.7 , Film material: 100 parts of 40% dispersion of polystyrene, 1 part of 40% aqueous solution of sodium polyacrylate, 14 parts of styrene / butadiene latex having a solid concentration of 48%, polyvinyl alcohol (saponification degree 88%, polymerization degree 1000) A composition comprising 50 parts of a 10% aqueous solution and 40 parts of water was mixed and stirred to obtain a coating solution for an undercoat layer.

-Solution A preparation 3- (N-ethyl-p-toluidino) -6-methyl-7-arininofluorane 10 parts, 5 parts of a 5% aqueous solution of methylcellulose, and a composition comprising 40 parts of water with a sand mill average particle size Was crushed until the thickness became 0.5 μm.

-Preparation of solution B 2,6-bis [(4-hydroxyphenyl) methyl] -4- (tert-butyl) phenol, 20 parts, polyvinyl alcohol (trade name: Go-Selan L-3266, Nippon Synthetic Chemical Co., Ltd.) A composition comprising 20 parts of a 10% aqueous solution and 10 parts of water was dispersed with a vertical sand mill (manufactured by Imex Co., Ltd.) until the particle size became 1 μm.

C liquid preparation Composition consisting of 20 parts of di-p-methylbenzyl ester oxalate, 20 parts of 10% aqueous solution of polyvinyl alcohol (trade name: Go-Selan L-3266, manufactured by Nippon Synthetic Chemical Co., Ltd.) and 30 parts of water. The product was dispersed with a vertical sand mill (manufactured by Imex) until the particle size became 1 μm.

Preparation of solution D: 20 parts of di-p-chlorobenzyl oxalate ester, 20 parts of 10% aqueous solution of polyvinyl alcohol (trade name: Go-Selan L-3266, manufactured by Nippon Synthetic Chemical Co., Ltd.) and 30 parts of water The product was dispersed with a vertical sand mill (manufactured by Imex) until the particle size became 1 μm.

-Solution E preparation 1,5- (3-oxopentylene) bis (3- (3 '-(p-toluenesulfonyl) ureido) benzoate) 20 parts, polyvinyl alcohol (trade name: Go-Selan L-3266 , Nippon Synthetic Chemical Co., Ltd.) was dispersed in a vertical sand mill (manufactured by Imex) until the particle size became 1 μm.

Preparation of solution F 20 parts of 1,2-di (3-methylphenoxy) ethane, 20 parts of 10% aqueous solution of polyvinyl alcohol (trade name: Go-Selan L-3266, manufactured by Nippon Synthetic Chemical Co., Ltd.) and 30 parts of water The composition consisting of was dispersed with a vertical sand mill (manufactured by Imex) until the particle size became 1 μm.

-Preparation of coating solution for heat-sensitive recording layer 55 parts of A liquid, 90 parts of B liquid, 35 parts of C liquid, 10 parts of D liquid, 20 parts of E liquid, 170 parts of 10% aqueous solution of polyvinyl alcohol, 36% dispersion of zinc stearate 12 parts of a body (trade name: Hydrin Z-8, manufactured by Chukyo Yushi Co., Ltd.) and 50 parts of a calcium carbonate (trade name: Brilliant 15, manufactured by Shiraishi Kogyo Co., Ltd.) 50 parts were prepared by mixing and stirring.

-Preparation of heat-sensitive recording material After applying and drying the coating solution for the undercoat layer on one surface of 44 g / m ² of high-quality paper so that the coating amount after drying is 8 g / m ² , the coating solution for the heat-sensitive recording layer is added to the above. After coating and drying on the undercoat layer so that the coating amount after drying was 5 g / m ² , supercalendering was performed to obtain a heat-sensitive recording material.

Example 2
In the preparation of the liquid B of Example 1, 2,6-bis [(4-hydroxyphenyl) methyl] instead of 2,6-bis [(4-hydroxyphenyl) methyl] -4- (tert-butyl) phenol A heat-sensitive recording material was obtained in the same manner as in Example 1 except that -4- (sec-butyl) phenol was used.

Example 3
In the preparation of solution B of Example 1, 2,-[(4-hydroxyphenyl) methyl] -6 was used instead of 2,6-bis [(4-hydroxyphenyl) methyl] -4- (tert-butyl) phenol. A heat-sensitive recording material was obtained in the same manner as in Example 1 except that-(2-hydroxyphenyl) methyl] -4- (tert-butyl) phenol was used.

Example 4
In the preparation of solution B of Example 1, 2,-[(4-hydroxyphenyl) methyl] -6 was used instead of 2,6-bis [(4-hydroxyphenyl) methyl] -4- (tert-butyl) phenol. A heat-sensitive recording material was obtained in the same manner as in Example 1 except that-(2-hydroxyphenyl) methyl] -4- (sec-butyl) phenol was used.

Example 5
In the preparation of solution B of Example 1, 2,-[(4-hydroxyphenyl) methyl] -6 was used instead of 2,6-bis [(4-hydroxyphenyl) methyl] -4- (tert-butyl) phenol. Except for using 10 parts of-(2-hydroxyphenyl) methyl] -4- (sec-butyl) phenol and 10 parts of 2,6-bis [(4-hydroxyphenyl) methyl] -4- (sec-butyl) phenol Obtained a heat-sensitive recording material in the same manner as in Example 1.

Example 6
In Example 1, a thermosensitive recording material was obtained in the same manner as in Example 1 except that 10 parts of the D solution was changed to 5 parts.

Example 7
In Example 1, a thermosensitive recording material was obtained in the same manner as in Example 1 except that 10 parts of the D solution was changed to 17 parts.

Example 8
In Example 1, Example 1 was used except that Compound 2 was used instead of 1,5- (3-oxopentylene) bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate) in Liquid E. In the same manner, a heat-sensitive recording material was obtained.

Example 9
The first undercoat layer is coated on one side of a 44 g / m ² base paper by a blade coating method so that the coating amount after drying is 7.0 g / m ² and dried. The coating solution for the undercoat layer is applied and dried on the first undercoat layer by the rod coating method so that the applied amount after drying is 8.0 g / m ² without further winding. A heat-sensitive recording material was obtained in the same manner as in Example 1 except that the two undercoat layers were formed.

Example 10
In the preparation of solution A of Example 1, 3-di (n-butyl) amino-6-methyl-7 was used instead of 3- (N-ethyl-p-toluidino) -6-methyl-7-arininofluorane. A thermosensitive recording material was obtained in the same manner as in Example 1 except that anilinofluorane was used.

Example 11
In Example 1, a heat-sensitive recording material was obtained in the same manner as in Example 1 except that 20 parts of the liquid E was changed to 140 parts.

Comparative Example 1
A heat-sensitive recording material was obtained in the same manner as in Example 1 except that the E solution of Example 1 was not used.

Comparative Example 2
A thermosensitive recording material was obtained in the same manner as in Example 1 except that 22.5 parts of both the C and D solutions were used in the preparation of the thermosensitive recording layer coating solution of Example 1.

Comparative Example 3
A heat-sensitive recording material was obtained in the same manner as in Example 1 except that in the preparation of the heat-sensitive recording layer coating liquid of Example 1, the C and D liquids were not used and 45 parts of the F liquid was used.

Comparative Example 4
In the preparation of the liquid B of Example 1, 4-hydroxy, 4′-isopropoxydiphenyl sulfone (trade name: trade name) instead of 2,6-bis [(4-hydroxyphenyl) methyl] -4- (tert-butyl) phenol A thermal recording material was obtained in the same manner as in Example 1 except that D-8, Nippon Soda Co., Ltd.) was used.

Comparative Example 5
In the preparation of the liquid B of Example 1, 2,2′-bis (4-hydroxydiphenyl) propane (commercial product) instead of 2,6-bis [(4-hydroxyphenyl) methyl] -4- (tert-butyl) phenol A heat-sensitive recording material was obtained in the same manner as in Example 1 except that Name: Bisphenol A, manufactured by Mitsui Chemicals, Inc. was used.
Got

  The following evaluation test was performed on the heat-sensitive recording material thus obtained, and the results are shown in Table 1.

[Color development]
The obtained thermal recording material was developed using a thermal evaluation machine (trade name: TH-PMD, manufactured by Okura Electric Co., Ltd.) at an applied energy of 0.34 mJ / dot, and the color density of the resulting recorded image was measured using a Macbeth densitometer. It was measured in the visual mode (RD-914 type, manufactured by Macbeth).

〔Heat-resistant〕
The color density and background density of the recorded image after leaving the heat-sensitive recording material after recording obtained in the above [color development] evaluation test at 80 ° C. for 24 hours are measured with a Macbeth densitometer (RD-914 type, Macbeth Co., Ltd.). ) And the high temperature resistance was evaluated.

〔Oil resistance〕
Edible oil was applied to the recorded image with a cotton swab, wiped immediately and left at 20 ° C. for 24 hours, and then the color density of the recorded image was measured with a Macbeth densitometer (RD-914 type, manufactured by Macbeth Co.) in the visual mode. The plasticizer resistance was evaluated.

(Reprintability)
The thermosensitive recording medium is immersed in water at 20 ° C. for 24 hours, air-dried, and color-developed at an applied energy of 0.34 mJ / dot using a thermal evaluation machine (trade name: TH-PMD, manufactured by Okura Electric Co., Ltd.). The color density of the recorded image was measured in a visual mode of a Macbeth densitometer (RD-914 type, manufactured by Macbeth).

Claims (3)

On a support, a colorless or light-colored basic dye, a heat-sensitive recording layer provided with a heat-sensitive recording layer containing a colorant, the compound represented by the following general formula (1) is contained as the colorant,

(In the formula, R represents an n-butyl group, an iso-butyl group, a sec-butyl group, or a tert-butyl group.)
Further, the thermosensitive recording layer contains 1 to 50% by mass of oxalic acid di-p-methylbenzyl ester as a sensitizer and oxalic acid di-p-chlorobenzyl ester to oxalic acid di-p-methylbenzyl ester. In addition, a compound represented by the following general formula (2) and / or 1,5- (3-oxapentamethylene) bis (3- (3- (p-toluenesulfonyl) ureido) benzoate) was included. A heat-sensitive recording material characterized by

(Where n represents an integer of 1 to 7)   The compound represented by the general formula (2) and / or 1,5- (3-oxapentamethylene) bis (3- (3- (p-toluenesulfonyl) ureido) benzoate) is 3 to 3 with respect to the colorant. The heat-sensitive recording material according to claim 1, comprising 100% by mass.   An undercoat layer is provided between the support and the heat-sensitive recording layer, the undercoat layer is composed of two layers, the first undercoat layer and the second undercoat layer are composed of the same undercoat layer coating solution, The thermal recording material according to claim 1 or 2, wherein the ratio of the coating amount after drying of the undercoat layer and the second undercoat layer is from 2: 8 to 8: 2.