Thermal recording material

Abstract

To provide a thermal recording material that exhibits improved print density and anti-sticking properties, while using a developer that is highly biodegradable and environmentally suitable.SOLUTION: Provided is a thermal recording material comprising N-(m-tolylaminocarbonyl)-phenylalanine as a developer, at least one of 1,2-bis(3-methylphenoxy)ethane, 1,2-bis(phenoxy)ethane, and diphenyl sulfone as a sensitizer, and further containing at least one saturated fatty acid monoamide represented by general formula (1). This composition results in improved anti-sticking properties.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a heat-sensitive recording material, which uses N-(m-tolylaminocarbonyl)-phenylalanine as a developer and at least 1,2-bis(3-methylphenoxy)ethane, 1,2-bis(phenoxy)ethane and diphenylsulfone as sensitizers, and further contains at least one type of saturated fatty acid monoamide represented by the following general formula (1), thereby improving anti-sticking properties. General formula (1) [ka] (wherein R is an alkyl group having 11 to 21 carbon atoms). [Background technology]

[0002] In general, thermal recording materials are already widely used in which a colored recording is obtained by applying thermal energy (joule heat) to a basic dye that is colorless or light-colored at room temperature and an organic developer using a thermal head, thermal pen, etc.

[0003] The performance required for a thermal recording material is sufficient color density in the printed area and good print runnability. Some color developers have color development capabilities but poor print runnability, and depending on the color developer used, a sticking phenomenon may occur due to fusion between the thermal head and the thermal recording layer. In this phenomenon, many white streaks appear in the printed area, and these areas become blank, lowering the apparent color density. This phenomenon is particularly noticeable when low applied energy is applied when the color-developing components begin to melt, and it can also cause loads (damage) on the thermal head and head residue due to the molten material.

[0004] Some phenolic compounds used as color developers are suspected of being endocrine disruptors, and there is a tendency to restrict their use. For example, bisphenol A (2,2-bis(4-hydroxyphenyl)propane) was used in large quantities as a raw material for polyester and as a color developer for thermal paper, but it was designated as a second or third monitored chemical substance under the Law Concerning the Examination and Regulation of Manufacture, etc. of Chemical Substances before the amendment, and as a priority assessment chemical substance under the same law after the amendment. Furthermore, due to suspicion of being an endocrine disruptor, its use has already been voluntarily restricted in Europe, the United States, Canada, Japan, and other countries.

[0005] Furthermore, bisphenol S (4,4'-dihydroxydiphenyl sulfone) was registered as a designated chemical substance and regulated as a second monitoring chemical substance under the pre-revision Act on the Examination and Regulation of Manufacture, etc. of Chemical Substances due to suspicions of chromosomal abnormalities, etc. Furthermore, in Europe, it was registered as a substance of very high concern in January 2023 due to suspicions of reproductive toxicity and endocrine disruption to humans and the environment. In addition, restrictions on the use of similar phenol-based color developers are about to be implemented in various countries.

[0006] As a non-phenolic color developer such as a sulfonylurea compound, it has been proposed to use a synthetic compound such as 4,4'-diaminodiphenylalkane as a raw material (Patent Document 1). The use of a non-phenolic color developer using an acylated amino acid made mainly from a natural amino acid has also been proposed (Patent Document 2). In addition, a heat-sensitive recording material has been proposed that obtains an image by applying the browning reaction (Maillard reaction) caused by heating amino acids and sugars (Patent Document 3). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 05-147357 [Patent Document 2] Japanese Patent Application Publication No. 07-109423 [Patent Document 3] JP 2005-254764 A [Patent Document 4] Patent No. 6726048 Summary of the Invention [Problem to be solved by the invention]

[0008] However, the sulfonylurea compound proposed in Patent Document 1 has problems such as using a synthetic compound having a molecular structure similar to that of bisphenol A as a raw material as a constituent component, and furthermore, it cannot be said to be sufficient in terms of the performance required as a developer for thermal recording materials.

[0009] Regarding the use of a color developer using an acylated amino acid made primarily from a natural amino acid as described in Patent Document 2, although it does not fall into the category of substances causing endocrine disruption as described above, the quality performance of the acylated product does not meet the required performance as a color developer for thermal recording materials in terms of color density, whiteness, and various storage stability of unprinted and printed areas.

[0010] The proposal in Patent Document 3 to obtain an image by applying a browning reaction (Maillard reaction) caused by heating amino acids and sugars also does not satisfy the performance requirements as a color developer.

[0011] The present inventors have further investigated whether amino acids, which are also foodstuffs, can be used as color developers in thermal recording materials, and have found that amino acids do not develop color even when they come into contact with basic dyes, because a basic amino group and an acidic carboxyl group coexist in the same molecule and are neutralized within the molecule.

[0012] The present inventors have also completed an invention relating to a thermal recording material that uses an N-substituted amino acid derivative derived from a natural amino acid as a developer, in particular, as a developer by introducing a functional group that contributes to the required performance and color-developing ability of the thermal recording material as a protecting group for the amino group of the amino acid, thereby eliminating intramolecular neutralization and further enhancing the color-developing ability of the amino acid (Patent Document 4).

[0013] Non-phenolic color developers such as N-(m-tolylaminocarbonyl)-phenylalanine proposed in Patent Document 4 are highly biodegradable and environmentally friendly. However, in order to popularize this N-(m-tolylaminocarbonyl)-phenylalanine, there remain issues to be overcome, such as improving print density and sticking resistance. [Means for solving the problem]

[0014] The main feature of the present invention is that it contains at least 1,2-bis(3-methylphenoxy)ethane, 1,2-bis(phenoxy)ethane and diphenylsulfone as sensitizers, and at least one saturated fatty acid monoamide.

[0015] [1] A basic dye that is colorless or light-colored at room temperature; N-(m-tolylaminocarbonyl)-phenylalanine as a developer capable of developing a color when contacted with the dye by heating; one or more sensitizers selected from the group consisting of 1,2-bis(3-methylphenoxy)ethane, 1,2-bis(phenoxy)ethane, and diphenylsulfone; The following general formula (1) [ka] (wherein R is an alkyl group having 11 to 21 carbon atoms), and a thermosensitive recording layer containing the same is provided on a support, and the thermosensitive recording material is characterized by excellent anti-sticking properties. [2] For every 100 parts by mass of the sensitizer, The heat-sensitive recording material according to [1], wherein the content of the saturated fatty acid monoamide is 1 to 300 parts by mass. [3] The heat-sensitive recording material according to [1], which has a print density of 0.72 or more when an applied energy of 0.24 mJ / dot is used, and a print density of 1.25 or more when an applied energy of 0.38 mJ / dot is used. Effect of the Invention

[0016] The present invention uses N-(m-tolylaminocarbonyl)-phenylalanine as the developer, at least 1,2-bis(3-methylphenoxy)ethane, 1,2-bis(phenoxy)ethane and diphenylsulfone as the sensitizer, and contains at least one type of saturated fatty acid monoamide represented by the general formula (1), thereby making it possible to obtain a thermal recording material that is less affected by the sticking phenomenon even when low energy is applied and has a high color density. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The thermal recording material of the present invention is a thermal recording material having a thermal recording layer provided on a support, the thermal recording layer containing a basic dye that is colorless or light-colored at room temperature and a developer that can develop color when contacted with the dye by heating, and is characterized in that N-(m-tolylaminocarbonyl)-phenylalanine is used as the developer, and at least 1,2-bis(3-methylphenoxy)ethane, 1,2-bis(phenoxy)ethane and diphenyl sulfone are used as sensitizers, and the material contains at least one type of saturated fatty acid monoamide represented by the general formula (1) above, thereby achieving color development that is less affected by the sticking phenomenon.

[0018] The heat-sensitive recording layer of the heat-sensitive recording material of the present invention is formed by preparing a coating liquid by adding the above-mentioned basic dye, developer, sensitizer, binder, filler, lubricant and various other additives, and coating the same on a support such as paper, plastic film, or processed paper.

[0019] The content of the saturated fatty acid monoamide represented by the general formula (1) is preferably 1 to 300 parts by mass, more preferably 3 to 200 parts by mass, and most preferably 5 to 100 parts by mass, based on 100 parts by weight of the sensitizer of 1,2-bis(3-methylphenoxy)ethane, 1,2-bis(phenoxy)ethane, and diphenylsulfone.

[0020] Examples of the saturated fatty acid monoamide used in the present invention include lauric acid monoamide, palmitic acid monoamide, stearic acid monoamide, and behenic acid monoamide. These fatty acid monoamides may be used alone or in combination of two or more.

[0021] In the heat-sensitive recording material of the present invention, examples of basic dyes which are colorless or light-colored at room temperature include triphenylmethane, fluoran, diphenylmethane, spiro, fluorene and thiazine compounds, and can be selected from conventionally known leuco dyes.

[0022] Basic dyes that are colorless or light-colored at room temperature include 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide, 3,3-bis(p-dimethylaminophenyl)phthalide, 3-(4-diethylamino-2-ethoxyphenyl)-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide, 3,3-bis(p-methylaminophenyl)-6-dimethylaminophthalide, 3-diethylamino-7-dibenzylaminobenzo[α]fluoran, 3-(1-ethyl-2-methylindol-3-yl)-3-(4-diethylamino-2-n-hexyloxyphenyl-4-azaphthalide, 3 -(1-ethyl-2-methylindol-3-yl)-3-(4-diethylamino)-2-methylphenyl-4-azaphthalide, 3-(4-diethylaminophenyl)-3-(1-ethyl-2-methylindol-3-yl)phthalide, 3-(2-methyl-1-n-octyl indol-3-yl)-3-(4-diethylamino-2-ethoxyphenyl)-4-azaphthalide, 3-(N-ethyl-N-isopentylamino)-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-(o,p-dimethylanilino)fluoran, 3-(N-ethyl-Np-toluidino)-6-methyl-7-anilinofluoran, 3-pyrrolidino-6-methyl-7-anilinofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 3-(N-cyclohexyl-N-methylamino)-6-methyl-7-anilinofluoran, 3-diethylamino-7-(o-chloroanilino)fluoran, 3-diethylamino-7-(m-trifluoromethylanilino)fluoran, 3-di(n-pentyl)amino-6-methyl-7-anilinofluoran, 3-[N-(3 -ethoxypropyl)-N-ethylamino]6-methyl-7-anilinofluoran, 3-(Nn-hexyl-N-ethylamino)-7-(o-chloroanilino)fluoran, 3-(N-ethyl-N-2-tetrahydrofurfurylamino)-6-methyl-7-anilinofluoran, 2,2-bis{4-[6'-(N-cyclohexyl-N-methylamino)-3'-methylspiro[phthalido-3,9'-xanthene]-2'-ylamino]phenyl}propane and 3-dibutylamino-7-(o-chloroanilino)fluoran. 3,6-Dimethoxyfluoran, 3-pyrrolidino-6-chlorofluoran, 3-diethylamino-6-methyl-7-chlorofluoran, 3-diethylamino-7-chlorofluoran, 3-diethylamino-7,8-dibenzofluoran, 3-diethylamino-6,7-dimethylfluoran, 3-(N-methyl-p-toluidino)-7-methylfluoran, 3-(N-methyl-N-isoamylamino)-7,8-benzofluoran, 3,3'-bis(1-n-amyl-2-methylindol-3-yl)phthalide, 3-(N-methyl- N-isoamylamino)-7-phenoxyfluoran, 3,3'-bis(1-n-butyl-2-methylindol-3-yl)phthalide, 3,3'-bis(1-ethyl-2-methylindol-3-yl)phthalide, 3,3'-bis(p-dimethylaminophenyl)phthalide, 3-(N-ethyl-Np-tolylamino)-7-(N-phenyl-N-methylamino)fluoran, 3-diethylamino-7-anilinofluoran, 3-diethylamino-7-benzylaminofluoran, 3-pyrrolidino-7-dibenzylaminofluoran The present invention is not limited to these, and two or more kinds may be used in combination.

[0023] Furthermore, in the present invention, a conventionally known storage stabilizer can be used in combination.

[0024] Examples of storage stabilizers include 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), 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,1,3-tris(2-methyl 4,4'-bis[(4-methyl-3-phenoxycarbonylaminophenyl)ureido]diphenyl sulfone, tris(2,6-dimethyl-4-tert-butyl-3-hydroxybenzyl)isocyanurate, 4,4'-thiobis(3-methylphenol), 4,4'-dihydroxy-3,3',5,5'-tetrabromodiphenyl sulfone, 4,4'-dihydroxy-3,3',5,5'-tetramethyldiphenyl sulfone, 2,2-bis(4-hydroxy-3,5- hindered phenol compounds such as 2,2-bis(4-hydroxy-3,5-dichlorophenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 1,4-diglycidyloxybenzene, 4,4'-diglycidyloxydiphenyl sulfone, 4-benzyloxy-4'-(2-methylglycyloxy)diphenyl sulfone, glycidyl terephthalate, bisphenol A type epoxy resin, cresol novolac type epoxy resin, phenol novolac type epoxy resin, etc. Examples of such compounds include epoxy compounds of the formula (I), N,N'-di-2-naphthyl-p-phenylenediamine, sodium salts or polyvalent metal salts of 2,2'-methylenebis(4,6-di-tert-butylphenyl)phosphate, bis(4-ethyleneiminecarbonylaminophenyl)methane, 4,4'-bis[(4-methyl-3-phenoxycarbonylaminophenyl)ureido]diphenylsulfone, and diphenylsulfone bridged compounds represented by the following general formula (2), but the present invention is not limited to these, and two or more of them may be used in combination.

[0025] (General formula 2) [ka] (In the formula, n represents an integer of 1 to 7.)

[0026] These storage stabilizers contribute to the storage stability of the printed portion of the heat-sensitive recording material.

[0027] The content of the storage stabilizer is preferably from 2.5 to 100 parts by mass, and more preferably from 5 to 50 parts by mass, based on 100 parts by mass of the color developer.

[0028] Examples of auxiliary agents include dispersants such as sodium dioctylsuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate, and fatty acid metal salts; waxes such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, and ester wax; hydrazide compounds such as adipate dihydrazide; water-resistant agents such as glyoxal, boric acid, dialdehyde starch, methylol urea, glyoxylates, and epoxy compounds; defoamers, coloring dyes, fluorescent dyes, and pigments.

[0029] Examples of binders used in the heat-sensitive recording layer in the present invention include fully saponified polyvinyl alcohols having a degree of polymerization of 200 to 1900, partially saponified polyvinyl alcohols, carboxy-modified polyvinyl alcohols, diacetone-modified polyvinyl alcohols, acetoacetyl-modified polyvinyl alcohols, amide-modified polyvinyl alcohols, sulfonic acid-modified polyvinyl alcohols, butyral-modified polyvinyl alcohols, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, styrene-maleic anhydride copolymers, styrene-butadiene copolymers, ethyl cellulose, acetyl cellulose and other cellulose derivatives, polyvinyl acetate, polyacrylamide, polyacrylic acid esters, polyvinyl butyral polystyrenes and their copolymers, polyamide resins, silicone resins, petroleum resins, terpene resins, ketone resins, chroman resins, etc. These binders may be used alone or in combination, and may be used dissolved in a solvent or in a state of being emulsified or dispersed in a paste form in water or other medium.

[0030] Examples of pigments that can be incorporated into the heat-sensitive recording layer include inorganic or organic pigments such as silica, calcium carbonate, kaolin, calcined kaolin, diatomaceous earth, talc, titanium oxide, zinc oxide, aluminum hydroxide, polystyrene resin, urea-formaldehyde resin, styrene-methacrylic acid copolymer, styrene-butadiene copolymer, and hollow plastic pigments.

[0031] In the present invention, the types and amounts of the basic dye, developer, sensitizer, binder, pigment and other additives used in the heat-sensitive recording layer are appropriately determined depending on the quality and performance required for the heat-sensitive recording layer.

[0032] In the thermosensitive recording layer of the present invention, the developer is preferably 0.5 to 5 parts by mass, more preferably 1 to 4 parts by mass, and most preferably 2 to 3 parts by mass, per part by mass of the basic dye in the thermosensitive recording layer from the viewpoint of color development density.

[0033] Furthermore, the amount of the sensitizer is preferably 0.2 to 4 parts by mass per part of the leuco dye, the amount of the sensitizer is preferably 0.1 to 4 parts by mass per part of the basic dye, and the amount of the binder is preferably 5 to 50% by mass of the total solid content. As the support, paper, recycled paper, synthetic paper, plastic film, nonwoven fabric, metal foil, etc. can be used. Also, a composite sheet combining these can be used.

[0034] In order to improve storage stability, an overcoat layer made of a polymeric substance containing an organic pigment may be provided, and in order to prevent adhesion of scum to the thermal head, improve print quality, and increase sensitivity, an undercoat layer containing an organic pigment, an inorganic pigment, hollow fine particles, or the like may be provided.

[0035] In the present invention, the basic dye, developer, sensitizer and, if necessary, storage stabilizer used in the heat-sensitive recording layer are finely dispersed in water as a dispersion medium by a stirring and grinding machine such as a ball mill, an attritor or a sand mill so that the average particle size becomes 2 μm or less.

[0036] If necessary, pigments, binders, auxiliaries, etc. are mixed and stirred into the finely dispersed dispersion to prepare a heat-sensitive recording layer coating material.

[0037] The thus obtained heat-sensitive recording layer coating is applied in a coating amount of 1.5 to 12 g / m2 after drying. 2 Approximately, more preferably 3 to 7 g / m 2 The coating is formed by applying the coating to a support so that the coating becomes approximately 100%.

[0038] When the print density of the prepared heat-sensitive recording material is measured with a Macbeth reflection densitometer RD-914 at an applied energy of 0.24 mJ / dot, it is preferably greater than 0.70, and more preferably 0.72 or more.

[0039] Furthermore, when the printing density is measured with a Macbeth reflection densitometer RD-914 at an applied energy of 0.24 mJ / dot, it is preferably greater than 1.24, and more preferably 1.25 or greater. EXAMPLES

[0040] The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited thereto. In the examples, "parts" and "%" represent "parts by mass" and "% by mass".

[0041] [Creating undercoat paint] An undercoat paint was prepared by mixing 100 parts of hollow plastic particles (product name: Ropeake SN-1055: hollow ratio: 55%, solid content: 26.5%), 100 parts of a 50% dispersion of calcined kaolin, 25 parts of a styrene-butadiene latex (product name: L-1571, solid content: 48%), 50 parts of a 10% aqueous solution of oxidized starch, and 20 parts of water.

[0042] Example 1 [Creating paint for thermal recording] Solution A (preparation of dye dispersion solution) 3-(N,N-dibutylamino)-6-methyl-7-anilinofluoran 10 parts 20% sulfonic acid modified polyvinyl alcohol (Product name: Gohsenex L-3266: manufactured by Mitsubishi Chemical Corporation) aqueous solution 5 parts Water 31.4 parts

[0043] Solution B (preparation of developer dispersion) N-(m-tolylaminocarbonyl)-phenylalanine 20 parts 20% sulfonic acid modified polyvinyl alcohol (Product name: Gohsenex L-3266) aqueous solution 10 parts Water 62.8 parts

[0044] Solution C (Preparation of sensitizer dispersion) 1,2-Bis(3-methylphenoxy)ethane (Sanko Co., Ltd.: KS232) 15 copies 20% sulfonic acid modified polyvinyl alcohol (Product name: Gohsenex L-3266) aqueous solution 7.5 parts Water 47.1 parts

[0045] The dispersions of the above-mentioned liquids A, B and C were ground in a sand grinder until the average particle size became 1 μm or less, and the dispersions were mixed in the following ratio to prepare a coating liquid. Solution A (dye dispersion) 46.4 parts B liquid (developer dispersion liquid) 92.8 parts Solution C (sensitizer dispersion) 69.6 parts Fatty acid monoamide (product name: Himicron L-271, manufactured by Chukyo Yushi Co., Ltd.) 20 parts of 25% dispersion

[0046] 228.8 parts by weight of the coating solution thus produced was mixed with 25 parts of aluminum hydroxide (product name: Hijilite H-42, manufactured by Showa Denko KK), 10 parts of amorphous silica (product name: Mizukasil P-605, manufactured by Mizusawa Chemical Industry Co., Ltd.), 100 parts of a 10% solution of oxidized starch, 15.3 parts of a zinc stearate dispersion (product name: Hydrin Z-8-36, manufactured by Chukyo Yushi Co., Ltd.), and 58 parts of water to produce 437.1 parts of a thermal recording coating material.

[0047] [Creating thermal recording materials] The substrate is a high-quality paper (acid paper) with a basis weight of 53 g, and the mass per area of ​​the undercoat paint after drying is 6 g / m 2 After that, the heat-sensitive paint is applied and dried so that the mass per area after drying is 3.8 g / m 2 The mixture was applied and dried. This sheet was treated with a supercalender to a smoothness (JISP8155:2010) of 900 to 1200s to prepare a thermal recording material.

[0048] [Thermal recording test] 1. Printing test The prepared thermal recording material was subjected to a thermal recording paper print tester (OHKURA ELECTRIC CO., LTD. TH-PMD) with applied energies of 0.24 mJ / dot and 0.38 mJ / dot. 2. Color development test The print density of the printed portion was measured with applied energy of 0.24 mJ / dot and 0.38 mJ / dot using a Macbeth reflection densitometer RD-914. The presence or absence of the sticking phenomenon was determined visually, and the evaluation criteria were as described below. 3. Sticking phenomenon confirmation test The sticking evaluation was performed by visual observation and judged as follows. 〇: No sticking phenomenon 〇-: There are slight traces of sticking. △: Sticking phenomenon is observed slightly. ×: Sticking phenomenon is frequently observed.

[0049] The results of various tests on the thermal recording material of this example are shown in Table 1.

[0050] Example 2 The same procedure as in Example 1 was carried out except that 40 parts of Solution C in Example 1 and 40 parts of Himicron L-271 were used. The results of various tests on the thermal recording material of this example are shown in Table 1.

[0051] Example 3 The same procedure as in Example 1 was carried out except that 70 parts of Solution C in Example 1 and 10 parts of Himicron L-271 were used. The results of various tests on the thermal recording material of this example are shown in Table 1.

[0052] Example 4 The same procedure as in Example 1 was repeated except that 76 parts of Solution C in Example 1 and 4 parts of Himicron L-271 were used. The results of various tests on the thermal recording material of this example are shown in Table 1.

[0053] Example 5 The same procedure as in Example 1 was carried out, except that the 1,2-bis(3-methylphenoxy)ethane in Solution C in Example 1 was changed to 1,2-bis(phenoxy)ethane (KS235, manufactured by Sanko Co., Ltd.). The results of various tests on the thermal recording material of this example are shown in Table 1.

[0054] Example 6 The same procedure as in Example 1 was carried out, except that the 1,2-bis(3-methylphenoxy)ethane in the C solution was changed to diphenyl sulfone (DPS). The results of various tests on the thermal recording material of this example are shown in Table 1.

[0055] [Comparative Example 1] The same procedure as in Example 1 was carried out, except that 80 parts of Solution C in Example 1 and no Hymicron L-271 were used. The test results are shown in Table 1.

[0056] [Comparative Example 2] The same procedure as in Example 1 was carried out, except that 80 parts of Solution C in Example 5 and no Hymicron L-271 were used. The test results are shown in Table 1.

[0057] [Comparative Example 3] The same procedure as in Example 1 was carried out, except that 80 parts of Solution C in Example 6 and no Hymicron L-271 were used. The test results are shown in Table 1.

[0058] [Table 1]

[0059] As is clear from the examples and Table 1, in the system using N-(m-tolylaminocarbonyl)-phenylalanine as the developer, improved color density was observed, the sticking phenomenon was reduced, and a good thermal recording material was obtained. [Industrial Applicability]

[0060] The thermal recording material of the present invention uses N-(m-tolylaminocarbonyl)-phenylalanine, a highly safe color developer, and is a thermal recording material with good color density and little sticking phenomenon.It has great industrial applicability as an alternative to conventional thermal recording materials that use phenolic color developers, the safety of which is questionable.

Claims

1. A basic dye that is colorless or light-colored at room temperature, N-(m-tolylaminocarbonyl)-phenylalanine as a developer capable of developing a color when contacted with the dye by heating; one or more sensitizers selected from the group consisting of 1,2-bis(3-methylphenoxy)ethane, 1,2-bis(phenoxy)ethane, and diphenylsulfone; The following general formula (1) 【Chemistry 1】 (wherein R is an alkyl group having 11 to 21 carbon atoms), and a heat-sensitive recording layer containing the same is provided on a support. A heat-sensitive recording material characterized by excellent anti-sticking properties.

2. 2. The heat-sensitive recording material according to claim 1, wherein the content of said saturated fatty acid monoamide is 1 to 300 parts by mass per 100 parts by mass of said sensitizer.

3. 2. The heat-sensitive recording material according to claim 1, wherein the print density is 0.72 or more when an applied energy of 0.24 mJ / dot is applied, and the print density is 1.25 or more when an applied energy of 0.38 mJ / dot is applied.

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