JP6965002B2 - Thermal recording material - Google Patents

Description

The present invention relates to a heat-sensitive recording material, and more particularly to a heat-sensitive recording material using an N-substituted amino acid derivative as a color developer.

In general, the heat-sensitive recording material is a heat-sensitive recording material in which color recording can be obtained by applying thermal energy (dieur heat) of a heat-sensitive head, a heat pen, etc., using a basic dye that is colorless or light-colored at room temperature and an organic color developer. Has already been widely put into practical use.

The performance required for the thermal recording material includes the whiteness of the unprinted portion, the whiteness of the unprinted portion under various environmental conditions, the color density of the printed portion, and the storage stability of the printed portion.
The storage stability of the printed part means that the printed image does not disappear even when it is placed in a high humidity environment, when water adheres, when oils adhere, or when a plasticizer adheres. do.

On the other hand, the required performance of printing formed by the heat-sensitive recording material largely depends on the dye, the color developer, and the sensitizer, which are the main components of the heat-sensitive recording material, and the influence of the color developer is particularly large. Therefore, synthetic compounds derived from petrochemicals such as phenolic compounds and sulfonylurea compounds have been proposed as color developers that satisfy the above-mentioned required performance. Among them, many phenolic compounds have been developed and put into practical use.

However, some phenolic compounds are suspected of being endocrine disruptors, and their use tends to be suppressed. For example, bisphenol A (2,2-bis (4-hydroxyphenyl) propane) was used in large quantities as a raw material for polyester and as a developer for thermal paper, but before the revision, examination and production of chemical substances, etc. In the regulation law, it is recognized as a second and third monitoring chemical substance, and in the revised law, it is recognized as a priority evaluation chemical substance, and its use is suspected to be an endocrine disturbing substance in the EU, the United States, Canada, and Japan. It has already been refrained from doing so in countries.

Bisphenol S (4,4'-dihydroxydiphenylsulfone) is registered as a designated chemical substance under the Act on Regulation of Examination and Production of Chemical Substances before the revision due to suspicion of chromosomal abnormalities, etc., and is regulated as a second monitoring chemical substance. It had been.

As a non-phenolic color developer such as a sulfonylurea compound, there is a proposal 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 using a natural amino acid as a main raw material has been proposed (Patent Document 2). Further, a heat-sensitive recording material for obtaining an image by applying a browning reaction (Maillard reaction) by heating amino acids and sugars has also been proposed (Patent Document 3).

Japanese Unexamined Patent Publication No. 05-147357 Japanese Unexamined Patent Publication No. 07-109423 Japanese Unexamined Patent Publication No. 2005-254764

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 thereof, and is also required as a color developer for a heat-sensitive recording material. It was not sufficient for performance.

The use of a color developer using an acylated amino acid made from a natural amino acid as a main raw material in Patent Document 2 is not in the category of the causative agent of endocrine disrupting described above, but the acylated product has a color development density, whiteness and not yet. In terms of various storage stability of the printed part, the printed part, etc., the quality performance does not reach the required performance as a color developer of the heat-sensitive recording material.

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

The present invention has been made in view of the above circumstances, and satisfies the required performance as a color developer such as color density, whiteness, and storage stability of the printed portion, and there is no concern about endocrine disrupting action. -Providing a heat-sensitive recording material using a substituted amino acid derivative.

The present inventors have studied from the viewpoint of whether amino acids, which are also foods, can be used as a color developer for heat-sensitive recording materials. As a result, it was found that the amino acid does not develop color even when it comes into contact with the basic dye because the basic amino group and the acidic carboxyl group coexist in the same molecule and are neutralized in the molecule. By introducing a functional group that contributes to the required performance and color-developing ability of a heat-sensitive recording material as a color developer as a protecting group for the amino group of an amino acid, the present inventors eliminate intramolecular neutralization and further amino acids. Has been strongly expressed, and in particular, the present invention using an N-substituted amino acid derivative made from a natural amino acid as a developing agent has been completed.

The present invention is a heat-sensitive recording material provided on a support with a heat-sensitive recording layer containing a basic dye that is colorless or light-colored at room temperature and a color developer that can come into contact with the dye and develop a color by heating. The color developer is a heat-sensitive recording material which is at least one of the N-substituted amino acid derivatives represented by the following general formula (1), and is used as a storage stabilizer in the heat-sensitive recording layer under the following general formula (2). A thermal recording material containing a diphenylsulfone crosslinked compound represented by.
( _{RX) m-} Y- (Z) _m ... (1)
(In the formula (1), R is an alkyl group having an aryl group of C6 to C10, an alkyl group of C1 to C8, an aralkyl group of C7 to C11, an aryl group of C6 to C10, or an alkoxy group of C1 to C8. Represents an aryl group which may have a substituent of.
X is a group attached to the N-terminus of _{Y, -OCO -, - SO 2} NHCO -, - NHCO -, - NHCS-, or -SO ₂ - represent.
Y represents an amino acid residue or a peptide residue, and the OH group of the serine residue, threonine residue, aspartic acid residue, glutamate residue, or tyrosine residue in the Y group is an OR group or an OR "group. The SH group of the cysteine residue may be substituted with an SR group or an SR "group, and the NH group of a histidine residue may be substituted with an NR group or an NR'group. _{Often, the two} NH groups of a lysine or ornithine residue may be substituted with an NHR or NHR'group, where R'represents an amino-protecting group and R'represents a carboxy-protecting group.
Z is a group attached to the C-terminus of Y and represents an OH group or an OR "group.
The plurality of R, R', R "may be the same or different, and may be combined with each other to form a ring.
However, Y is an amino acid residue other than the cystine residue or a peptide residue having no cystine residue, and m = 1. )

(In the formula, n represents an integer of 1 to 7.)

The color formers are N- (m-tolylaminocarbonyl) -phenylalanine, N- (m-tolylaminocarbonyl) -methionine, N- (p-tolylaminocarbonyl) -methionine, N- (phenylaminocarbonyl) -methionine. , N- (m-tolylaminocarbonyl) -valine, N- (m-tolylaminocarbonyl) -phenylglycine and N- (m-tolylaminocarbonyl) -tyrosine. preferable.

The color developer of the derivative derived from the N-substituted amino acid constituting the present invention satisfies the required performance of the heat sensitive recording material equivalent to that of the conventional color developer, and is safe heat sensitive without endocrine disrupting action. Recording material can be provided.

The heat-sensitive recording material of the present invention is a heat-sensitive recording layer provided on a support with a heat-sensitive recording layer containing a colorless or light-colored basic dye at room temperature and a color developer capable of developing color by contacting the dye by heating. It is a material.

The heat-sensitive recording material of the present invention is a heat-sensitive recording layer provided on a support with a heat-sensitive recording layer containing a colorless or light-colored basic dye at room temperature and a color developer that can come into contact with the dye and develop color by heating. It is a material, and the color developer is at least one kind of N-substituted amino acid derivative represented by the following general formula (1). The heat-sensitive recording layer of the heat-sensitive recording material of the present invention is obtained by adding the basic dye, the color developer represented by the general formula, a binder, a sensitizer, a filler, a lubricant, and various other additives. A coating liquid is prepared and coated on a support such as paper, plastic film, or processed paper to form the coating liquid.

In the heat-sensitive recording material of the present invention, the color developer is at least one of the N-substituted amino acid derivatives represented by the following general formula (1).
( _{RX) m-} Y- (Z) _m ... (1)

In formula (1), R is an alkyl group having an aryl group of C6 to C10, an alkyl group of C1 to C8, an aralkyl group of C7 to C11, an aryl group of C6 to C10, or an alkoxy group of C1 to C8. Represents an aryl group that may have a substituent. Examples of the alkyl group having an aryl group of C6 to C10 include a benzyl group, a phenethyl group, an o-tolylmethyl group, an m-tolylmethyl group, a p-tolylmethyl group, an o-tolylethyl group, an m-tolylethyl group and a p-tolylethyl group. Can be mentioned. Examples of the aryl group which may have a substituent of the alkyl group of C1 to C8 include an o-tolyl group, an m-tolyl group, a p-tolyl group, a 1-ethylphenyl group, a 2-ethylphenyl group and a 3-ethyl group. Phenyl group, 1-propylphenyl group, 2-propylphenyl group, 3-propylphenyl group, 1-butylphenyl group, 2-butylphenyl group, 3-butylphenyl group, 1-pentylphenyl group, 2-pentylphenyl group , 3-Pentylphenyl group and the like. Examples of the aryl group which may have a substituent of the aralkyl group of C7 to C11 include a p-benzylbiphenyl group and the like. Examples of the aryl group which may have a substituent of the aryl group of C6 to C10 include a biphenyl group and a 3,3'-dimethylbiphenyl group. Examples of the aryl group which may have a substituent of the alkoxy group of C1 to C8 include a 6-methoxyphenyl group.

X is a group attached to the N-terminus of _{Y, -OCO -, - SO 2} NHCO -, - NHCO -, - NHCS-, or -SO ₂ - represents a (sulfonyl group).

Y represents an amino acid residue or a peptide residue, and the OH group of the serine residue, threonine residue, aspartic acid residue, glutamate residue, or tyrosine residue in the Y group is an OR group or an OR "group. The SH group of the cysteine residue may be substituted with an SR group or an SR "group, and the NH group of a histidine residue may be substituted with an NR group or an NR'group. _{Often, the two} NH groups of a lysine or ornithine residue may be substituted with an NHR or NHR'group, where R'represents an amino-protecting group and R'represents a carboxy-protecting group. As an amino protective group (R'group) that protects the NH group of the histidine residue or the NH ₂ group of the lysine residue or the ornithine residue, an RX group is mentioned, and in addition, an acyl group and an alkyl group are used. Examples of the carboxy-protecting group (R "group) that protects the aspartic acid residue or the glutamate residue in the Y group include an alkoxy group, an aryloxy group, an amino group, an alkylamino group, and an arylamino group. Further, as a protective group of a serine residue, a threonine residue, or a tyrosine residue of an OH group in a Y group, or an SH group of a cysteine residue, the above-mentioned carboxy protecting group (R "group) can be mentioned.

Z is a group attached to the C-terminus of Y and represents an OH group or an OR "group.
The plurality of R, R', R "may be the same or different, and may be combined with each other to form a ring.
However, Y is an amino acid residue other than the cystine residue or a peptide residue having no cystine residue, and m = 1.

The N-substituted amino acid derivative represented by the general formula can be easily produced from an amino acid or an amino acid derivative and a sulfonated product, an isocyanate compound or the like by applying a known method such as the Schotten-Baumann reaction.

The amino acids, peptides and their esters and amides used as constituents of the compounds represented by the general formula may be L-form, D-form or DL-form. It may be a natural amino acid, an unnatural amino acid, an α-amino acid, or a β-amino acid. Esters are C1-C4 alkyl esters, aryl esters, aralkyl esters, and amides are amides, alkyl-substituted amides, aryl-substituted amides and the like.

Specifically, ester derivatives such as glycine, glycine methyl ester, glycine ethyl ester, glycine-t-butyl ester, glycine phenyl ester, glycine p-cresyl ester, glycine m-cresyl ester, and glycine benzyl ester, glycine amide, N. '-Amid derivatives such as methylglycine amide and glycylanilide, ester derivatives such as phenylglycine, phenylglycine methyl ester, phenylglycine ethyl ester and phenylglycine benzyl ester, phenylglycine amide, alanine, alanine methyl ester, alanine ethyl ester, Ester derivatives such as alanine benzyl ester, ester derivatives such as alanine amide, phenylalanine, naphthylalanine, phenylalanine methyl ester, phenylalanine ethyl ester and phenylalanine benzyl ester, amide derivatives such as phenylalanine amide, N'-methylphenylalanine amide and phenylalanylanilide , Valin, valine methyl ester, valine methyl ester, valine isopropyl ester, valine-t-butyl ester, valine benzyl ester and other ester derivatives, valine amide, leucine, leucine methyl ester, isoleucine, serine, o-methylserine, o-benzylserine Ester derivatives such as o-substituted serine, serine methyl ester, and serine benzyl ester, esters such as threonine, o-methylthreonine, o-benzylthreonine and the like, o-substituted threonine, threonine methyl ester, threonine-t-butyl ester and the like. Derivatives, tyrosine, o-methoxytyrosine, o-benzyloxytyrosine, o-substituted tyrosine such as tyrosine, ester such as 3- (3', 4'-dihydroxyphenyl) alanine (DOPA), tyrosine methyl ester, tyrosine benzyl ester Derivatives, tyrosine amide, proline, hydroxyproline, proline methyl ester, proline-t-butyl ester, prolin benzyl ester and other ester derivatives, proline amide, lysine, ornithine, lysine methyl ester, lysine ethyl ester, lysine benzyl ester, ornithine methyl Esters, ester derivatives such as ornithine ethyl ester, ornithine benzyl ester, arginine, arginine methyl ester, arginine ethyl ester, histi S-substituted cysteines such as gin, histidine methyl ester, tryptophan, tryptophan methyl ester, tryptophan benzyl ester, tryptophanamide, cysteine, cystine, S-methylcysteine, S-ethylcysteine, S-benzylcysteine, S-phenylcysteine, cysteine Ester derivatives such as methyl ester and cysteine benzyl ester, S-oxidized derivatives such as cysteine sulfoxide and sulfone, S-oxidized derivatives such as methionine, methionine sulfoxide and methionine sulfone, ester derivatives such as methionine methyl ester and methionine benzyl ester, methionine amide , Asparaginic acid, aspartic acid methyl ester, aspartic acid ethyl ester, aspartic acid benzyl ester and other ester derivatives, asparagine, glutamic acid, glutamic acid methyl ester, glutamic acid ethyl ester, glutamic acid benzyl ester and other ester derivatives, and glutamine. Further, it may be an amino acid such as homoserine, homocysteine, norleucine and a derivative thereof. In addition, C1-C8 aminocarboxylic acids such as β-alanine, 5-aminovaleric acid, and 7-aminoheptanoic acid are also selected.

Peptides are glycylglycine, glycylglycine methyl ester, glycylglycine amide, glycyl alanine, glycyl alanine methyl ester, glycyl valine, glycyl leucine, glycyl phenylalanine, glycyl phenylalanine methyl ester, glycyl phenylalanine amide, glycyl. Examples thereof include proline, alanylalanine, alanylproline, alanylmethionine, alanylmethionine methyl ester, alanylphenylalanine, and glycylglycylglycine.

The compound represented by the general formula is an amino acid or peptide having a protected amino group and a derivative thereof, and the protecting group is widely used in the fields of amino acid chemistry or peptide synthesis chemistry.

As the functional group (-XNH- group) formed by the N-substituted group of the N-substituted amino acid derivative represented by the general formula (1) in the heat-sensitive recording material of the present invention, a sulfonylamino group, a urethane group, ( Tio) urea group (ureid), sulfonylurea group, and these functional groups, for example, the sulfonylamino group is derived from arylsulfonyl chloride. The urethane group is derived from a chloroformate ester such as benzyl chloroformate or a carbonic acid ester such as diphenyl carbonate. The (thio) urea group is derived from an iso (thio) cyanate ester such as phenyl iso (thio) cyanate. Sulfonylureas are derived from sulfonylureas such as toluenesulfonylisocyanates.

Specifically, examples of the compound (X1) forming a sulfonylamino group include benzenesulfonyl chloride, p-toluenesulfonyl chloride, m-toluenesulfonyl chloride, o-toluenesulfonyl chloride, p-methoxybenzenesulfonyl chloride, and p-chloride. Examples thereof include chlorides such as xylene sulfonyl, m-xylene sulfonyl chloride, mecitylene sulfonyl chloride, 1-naphthalene sulfonyl chloride and 2-naphthalene sulfonyl chloride, bromide and iodide.

Examples of the compound (X2) forming a urethane group include halogenated formic acid esters such as benzyl chloroformate and chlorogiate phenyl ester, and carbonic acid esters such as diphenyl carbonate and dibenzyl carbonate.

Examples of the compound (X3) forming the (thio) urea group include benzyl isocyanate, phenyl isocyanate, p-tolyl isocyanate, m-tolyl isocyanate, o-tolyl isocyanate, 1-naphthyl isocyanate, 2-naphthyl isocyanate, and phenylene 1,4. -Diisocyanate, phenylene 1,3-diisocyanate, tolylen 2,4-diisocyanate, tolylen-2,6-diisocyanate, p-xylylene diisocyanate, m-xylylene diisocyanate, naphthalene 1,5-diisocyanate, 4,4' -Diisocyanate-3,3'-dimethylbiphenyl, methylenediphenyl-4,4'-diisocyanate, 4,4'-diisocyanate-3,3'-dimethyldiphenylmethane, phenylisocyanate, m-tolyliso Examples thereof include thiocyanate and p-tolylisocyanate.

Examples of the compound (X4) forming a sulfonylurea group include benzenesulfonylisocyanate and p-toluresulfonylisocyanate.

Examples of the N-substituted amino acid derivative obtained by using the compound (X1) forming a sulfonylamino group according to the general formula (1) include N-benzenesulfonyl-glycine and N-benzenesulfonyl-glycine methyl ester. N-Benzenesulfonyl-glycineamide, N-benzenesulfonyl-methionine methyl ester, N-benzenesulfonyl-cysteine-S-benzyl, N- (p-toluenesulfonyl) -glycine, N- (p-toluenesulfonyl) -alanine, N- (p-toluenesulfonyl) -β-alanine, N- (p-toluenesulfonyl) -phenylalanine, N- (p-toluenesulfonyl) -phenylalanine methyl ester, N- (p-toluenesulfonyl) -phenylalanine benzyl ester, N- (p-toluenesulfonyl) -methionine, N- (p-toluenesulfonyl) -methionine benzyl ester, N- (m-toluenesulfonyl) -isoleucine, 3-N- (o-toluenesulfonyl) aminocaproic acid, N- (2,4-Xylenesulfonyl) -alanine, N- (2,4,6-mesitylensulfonyl) -serine, N- (p-ethylbenzenesulfonyl) -threonine, N, N'-di (pt-butylbenzene) N-arylsulfonyl-amino acids such as sulfonyl) -lysine, N, N'-di (pt-butylbenzenesulfonyl) -ornithine, N- (1-naphthalenesulfonyl) -tryptophan, N-2-naphthalenesulfonyl-asparagin , Esters and amides, N-aralkylsulfonyl-amino acids such as N-benzylsulfonyl-valine, N-benzylsulfonyl-tyrosine, N-benzylsulfonyl-phenylglycine, esters and amides and the like.

Examples of the N-substituted amino acid derivative obtained by using the compound (X3) forming a urea group in the general formula (1) include N-phenylaminocarbonyl-glycine and N-phenylaminocarbonyl-glycine-methyl. Estel, N-phenylaminocarbonyl-glycine benzyl ester, N-phenylaminocarbonyl-glycinamide, N-phenylaminocarbonyl-alanine, N-phenylaminocarbonyl-alanine-methyl ester, N-phenylaminocarbonyl-β-alanine, N-phenylaminocarbonyl-methionine, N-phenylaminocarbonyl-methionine-methyl ester, N-phenylaminocarbonyl-glutamine, N, N'-di (phenylaminocarbonyl) -lysine, N, N'-di (phenylamino) Carbonyl) -ornithine, N-phenylaminocarbonyl-phenylalanine, N-phenylaminocarbonyl-norvaline, N- (p-trillaminocarbonyl) -glycine, N- (p-trillaminocarbonyl) -alanine, N- (p-) Trillaminocarbonyl) -valine, N- (p-tolylaminocarbonyl) -phenylalanine, N- (p-tolylaminocarbonyl) -cysteine-S-benzyl, N- (p-tolylaminocarbonyl) -methionine, N-( p-tolylaminocarbonyl) -glutamic acid, N- (p-tolylaminocarbonyl) -glutamine, N- (m-tolylaminocarbonyl) -glycine, N- (p-tolylaminocarbonyl) -glycylglycine, N- ( p-Tolylaminocarbonyl) -glycylglycylglycine, N- (m-tolylaminocarbonyl) -glycylalanine, N- (m-tolylaminocarbonyl) -leucylalanine, N- (m-tolylaminocarbonyl)- Methionine, N- (m-trillaminocarbonyl) -methionine-sulfone, N- (m-trillaminocarbonyl) -valine, N- (m-trillaminocarbonyl) -tyrosine, N- (m-trillaminocarbonyl)- Tyrosine-methyl ester, N- (m-tolylaminocarbonyl) -phenylalanine,
N- (m-tolylaminocarbonyl) -methionine, N- (m-tolylaminocarbonyl) -valine, N- (m-tolylaminocarbonyl) -phenylglycine, N- (m-phenylglycine, N- (3-) It is good to use at least one selected from the group consisting of isopropenyl-α, α-dimethylbenzyl) aminocarbonyl-methionine, and N- (m-tolylaminocarbonyl) -tyrosine.

N- (m-tolylaminocarbonyl) -phenylalanine-methyl ester, N- (m-tolylaminocarbonyl) -phenylalanine-ethyl ester, N- (m-tolylaminocarbonyl) -phenylalanine-benzyl ester, N- (m-) Trillaminocarbonyl) -β-phenylalaninamide, N, N'-di (m-tolylaminocarbonyl) -lysine, N, N'-di (m-tolylaminocarbonyl) -lysine-methylester, N, N'- Di (m-tolylaminocarbonyl) -ornithine, N, N'-di (m-tolylaminocarbonyl) -ornithine-methylester, N- (m-tolylaminocarbonyl) -glutamic acid, N- (o-tolylaminocarbonyl) ) -Alanine, N- (o-tolylaminocarbonyl) -homoseline, N- (o-tolylaminocarbonyl) -valine, 1,6-hexamethylenebis (N-aminocarbonyl-phenylalanine), 2,4-phenylenebis (N-aminocarbonyl-phenylalanine), 1,3-trilenbis (N-aminocarbonyl-phenylglycine) and the like can be mentioned.

Examples of the N-substituted amino acid derivative obtained by using the compound (X3) forming a thiourea group according to the general formula (1) include N-phenylaminothiocarbonyl-phenylalanine and N-phenylaminothiocarbonyl-. Phenylalanine-methyl ester, N-phenylaminothiocarbonyl-valine-isopropyl ester, N-phenylaminothiocarbonyl-tyrosine-methyl ester, N-phenylaminothiocarbonyl-methionine-methyl ester, N-phenylaminothiocarbonyl-glycyl Glycin, N-phenylaminothiocarbonyl-glycylalanine, Nm-tolylaminothiocarbonyl-phenylalanine, Nm-tolylaminothiocarbonyl-phenylalanine-benzyl ester, Nm-tolylaminothiocarbonyl-phenylalanine amide, Nm-tolylaminothiocarbonyl-valine, Nm-tolylaminothiocarbonyl-valine-isopropyl ester, N-m-tolylaminothiocarbonyl-methionine-methyl ester, N-m-tolylaminothiocarbonyl-glycyl Glycin, Np-tolylaminothiocarbonyl-phenylalanine, Np-tolylaminothiocarbonyl-phenylalanine-benzyl ester, Np-tolylaminothiocarbonyl-phenylalanine amide, Np-tolylaminothiocarbonyl-valine, Examples thereof include Np-tolylaminothiocarbonyl-valine-isopropyl ester, N-p-tolylaminothiocarbonyl-methionine-methyl ester, N-p-tolylaminothiocarbonyl-glycylglycine and the like.

Examples of the N-substituted amino acid derivative obtained by using the compound (X2) forming a urethane group in the general formula (1) include N-benzyloxycarbonyl-glycine and N-benzyloxycarbonyl-phenylglycine. N-benzyloxycarbonyl-valine, N-benzyloxycarbonyl-methionine, N-benzyloxycarbonyl-tyrosine, N-benzyloxycarbonyl-hydroxyproline, N-benzyloxycarbonyl-arginine, N-benzyloxycarbonyl-glycine, etc. Can be mentioned.

Examples of the N-substituted amino acid derivative obtained by using the compound (X4) forming a sulfonylurea group according to the general formula (1) include N- (p-toluenesulfonylaminocarbonyl) -glycine and N- ( p-Toluenesulfonylaminocarbonyl) -phenylalanine, N- (p-toluenesulfonylaminocarbonyl) -phenylalanine-methyl ester, N- (p-toluenesulfonylaminocarbonyl) -phenylalanine-ethyl ester, N- (p-toluenesulfonylamino) Carbonyl) -phenylalanine amide, N- (p-toluenesulfonylaminocarbonyl) -β-alanine, N- (p-toluenesulfonylaminocarbonyl) -β-alanine-methylester, N- (p-toluenesulfonylaminocarbonyl)- Methionine-methyl ester, N- (p-toluenesulfonylaminocarbonyl) -leucine, N, N'-di (p-toluenesulfonylaminocarbonyl) -lysine-methylester, N, N'-di (p-toluenesulfonylamino) Carbonyl) -ornithine-methyl ester and the like can be mentioned.

Hexamethylene-1,6-diisocyanate, phenylene 1,4-diisocyanate, phenylene 1,3-diisocyanate, tolylen 2,4-diisocyanate, tolylen-2,6-diisocyanate, p-xylylene diisocyanate, m-xylyl Range Isocyanate, Naphthalene 1,5-Diisocyanate, 4,4'-Diisocyanate-3,3'-Dimethylbiphenyl, Methylenediphenyl-4,4'-Diisocyanate, 4,4'-Diisocyanate- The N-substituted amino acid derivative obtained by using a diisocyanate compound such as 3,3'-dimethyldiphenylmethane may have an isocyanate group as an R group, and a serine residue and a threonine residue in the Y group, aspartic acid residue, OH groups of glutamic acid residues, or a tyrosine residue, SH groups of cysteine residues, NH group of a histidine residue, or reacts with NH ₂ groups of lysine residues or ornithine residues, ring May be formed.

Protects _{the NH group of histidine residue in the Y group or the NH 2} group of lysine residue or ornithine residue of the N-substituted amino acid derivative represented by the general formula (1) in the heat-sensitive recording material of the present invention. Examples of the amino-protecting group (R'group) to be used include an RX group, and other examples include an acyl group and an alkyl group. These amino protecting groups (R'groups) can be introduced by known methods. For example, the acyl group can be introduced using an acid anhydride. The alkyl group can be introduced, for example, by an alkyl halide such as trityl chloride in the presence of an amine or the like.
As a carboxy protecting group (R "group) that protects an aspartic acid residue or a glutamate residue in the Y group of the N-substituted amino acid derivative represented by the general formula (1) in the heat-sensitive recording material of the present invention, alkoxy Examples thereof include a group, an aryloxy group, an amino group, an alkylamino group, an arylamino group, etc. Further, an OH group of a serine residue, a threonine residue, or a tyrosine residue in a Y group, or an SH group of a cysteine residue. Examples of the protecting group of the above include the carboxy protecting group (R "group). These carboxy protecting groups (R "groups) can be introduced by known methods.

Preferred N-substituted amino acid derivatives as a color developer in the heat-sensitive recording material of the present invention include N- (p-toluenesulfonyl) -glycine, N- (p-toluenesulfonyl) -alanine, and N- (p-toluenesulfonyl). N-allylsulfonyl-amino acids such as -β-alanine, N-phenylaminocarbonyl-glycine, N-phenylaminocarbonyl-valine, N- (m-tolylaminocarbonyl) -phenylalanine, N- (m-tolylaminocarbonyl) -Cysteine-S-benzyl, N- (m-trillaminocarbonyl) -methionine, N- (m-trillaminocarbonyl) -tyrosine, N- (p-trillaminocarbonyl) -phenylalanine, N- (p-trillamino) Carbonyl) -cysteine-S-benzyl, N- (p-tolylaminocarbonyl) -methionine, N- (p-tolylaminocarbonyl) -methionine, N- (phenylaminocarbonyl) -methionine, N- (p-tolylamino) N-aminocarbonyl-amino acids such as carbonyl) -tyrosine, particularly preferably N- (m-tolylaminocarbonyl) -phenylalanine, N- (m-tolylaminocarbonyl) -methionine, N- (p-tolylamino). Carbonyl) -methionine, N- (phenylaminocarbonyl) -methionine, N- (m-tolylaminocarbonyl) -valine, N- (m-tolylaminocarbonyl) -phenylglycine and N- (m-tolylaminocarbonyl)- Tyrosine can be mentioned.
One or more of these N-substituted amino acid derivatives may be used in combination.

Further, Z is preferably an OH group, X is preferably a -NHCO- group, and specifically, the N-substituted amino acid derivative is N- (m-tolylaminocarbonyl) -phenylalanine, N- ( m-tolylaminocarbonyl) -methionine, N- (p-tolylaminocarbonyl) -methionine, N- (phenylaminocarbonyl) -methionine, N- (m-tolylaminocarbonyl) -valine, N- (m-tolylaminocarbonyl) It is good to use at least one selected from the group consisting of carbonyl) -phenylglycine and N- (m-tolylaminocarbonyl) -tyrosine.

In the present invention, it may be used in combination with an existing color developer as long as the effect of the present invention is not impaired.

In the heat-sensitive recording material of the present invention, triphenylmethane-based, fluorane-based, diphenylmethane-based, spiro-based, fluorene-based, and thiazine-based compounds are examples of basic dyes that are colorless or pale at room temperature, and are selected from conventionally known leuco dyes. Can be done.
For example, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) phthalide,
3- (4-Diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindole-3-yl) -4-azaphthalide,
3,3-bis (P-methylaminophenyl) -6-dimethylaminophthalide,
3-Diethylamino-7-dibenzylaminobenzo [α] fluorane,
3- (1-Ethyl-2-methylindol-3-yl) -3- (4-diethylamino-2-n-hexyloxyphenyl-4-azaphthalide, 3- (1-ethyl-2-methylindol-3-) Il) -3- (4-diethylamino) -2-methylphenyl-4-azaphthalide, 3- (4-diethylaminophenyl) -3- (1-ethyl-2-methylindole-3-yl) phthalide, 3-( 2-Methyl-1-n-octylindole-3-yl) -3- (4-diethylamino-2-ethoxyphenyl) -4-azaphthalide, 3- (N-ethyl-N-isopentylamino) -6-methyl -7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7- (o, p-dimethylanilino) fluorane,

3- (N-ethyl-N-p-toluidino) -6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-7 -Anilinofluorane, 3- (N-cyclohexyl-N-methylamino) -6-methyl-7-anilinofluorane, 3-diethylamino-7- (o-chloroanilino) fluorane, 3-diethylamino-7- ( m-trifluoromethylanilino) fluorane, 3-di (n-pentyl) amino-6-methyl-7-anilinofluorane, 3- [N- (3-ethoxypropyl) -N-ethylamino] 6- Methyl-7-anilinofluorane, 3- (Nn-hexyl-N-ethylamino) -7- (o-chloroanilino) fluorane, 3- (N-ethyl-N-2-tetrahydrofurfurylamino)- 6-Methyl-7-anilinofluorane, 2,2-bis {4- [6'-(N-cyclohexyl-N-methylamino) -3'-methylspiro [phthalide-3,9'-xanthene] -2 '-Ilamino] phenyl} propane and 3-dibutylamino-7- (o-chloroanilino) fluorane,

3,6-dimethoxyfluorane, 3-pyrrolidino-6-chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7,8- Dibenzofluorane, 3-diethylamino-6,7-dimethylfluorane, 3- (N-methyl-p-toluizino) -7-methylfluorane, 3- (N-methyl-N-isoamylamino) -7,8 -Benzylfluorane, 3,3'-bis (1-n-amyl-2-methylindol-3-yl) phthalide, 3- (N-methyl-N-isoamylamino) -7-phenoxyfluorane, 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-N-p-tolylamino) -7- (N-phenyl-N-methylamino) fluorane, 3-diethylamino-7-anilinofluorane, 3- Diethylamino-7-benzylaminofluorane, 3-pyrrolidino-7-dibenzylaminofluorane and the like can also be selected, and the present invention is not limited thereto, and two or more of them may be used in combination. ..

A conventionally known sensitizer can be used in combination as the sensitizer of the present invention.
For example, fatty acid amides such as stearic acid amides, bisstearic acid amides and palmitic acid amides, p-toluenesulfonamides, stearic acids, calcium such as bechenic acid and palmitic acid, fatty acid metal salts such as zinc or aluminum, p-benzylbiphenyl. , Diphenylsulfone, benzyl benzyloxybenzoate, 2-benzyloxynaphthalene, 1,2-bis (p-tolyloxy) ethane, 1,2-bis (phenoxy) ethane, 1,2-bis (3-methylphenoxy) ethane , 1,3-Bis (phenoxy) propane, dibenzyl oxalate, p-methylbenzyl oxalate, m-terphenyl, 1-hydroxy-2-naphthoic acid and the like.

The heat-sensitive recording material of the present invention uses a diphenylsulfone cross-linked compound represented by the following general formula (2) as a storage stabilizer, and the storage stabilizer contributes to the storage stability of the printed portion of the heat-sensitive recording material of the present invention. do.

(In the formula, n represents an integer of 1 to 7.)

The content of the storage stabilizer is preferably 2 to 100 parts by mass, more preferably 5 to 50 parts by mass with respect to 100 parts by mass of the color developer.

The heat-sensitive recording material of the present invention contains a diphenylsulfone cross-linked compound represented by the above general formula (2) as a storage stabilizer, and by containing the storage stabilizer, particularly the printed portion of the heat-sensitive recording material. Water resistance is improved.

Furthermore, the present invention can also be used in combination with a conventionally known storage stabilizer.
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), 1,1,3-tris ( 2-Methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, 4,4'-bis [(4-4-bis) 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- Hinders such as hydroxy-3,5-dibromophenyl) propane, 2,2-bis (4-hydroxy-3,5-dichlorophenyl) propane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, etc. Dophenol compound, 1,4-diglycidyloxybenzene, 4,4'-diglycidyloxydiphenylsulfone, 4-benzyloxy-4'-(2-methylglycyloxy) diphenylsulfone, glycidyl terephthalate, bisphenol A type Epoxy compounds such as epoxy resin type, cresol novolac type epoxy resin, phenol novolac type epoxy resin, N, N'-di-2-naphthyl-p-phenylenediamine, 2,2'-methylenebis (4,6-di-tert) -Butylphenyl) Phosphate sodium salt or polyvalent metal salt, bis (4-ethyleneiminecarbonylaminophenyl) methane, 4,4'-bis [(4-methyl-3-phenoxycarbonylaminophenyl) ureido] diphenylsulfone, etc. Can be mentioned.

Examples of the auxiliary agent include dispersants such as sodium dioctiol succinate, sodium dodecylbenzene sulfonate, sodium lauryl alcohol sulfate, and fatty acid metal salts, zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, and the like. Waxes such as ester wax, hydrazide compounds such as dihydrazide adipate, water resistant agents such as glioxal, boric acid, dialdehyde starch, methylolurea, glyoxyphosphate, epoxy compounds, defoaming agents, coloring dyes, fluorescent dyes, etc. And pigments and the like.

The binder used for the heat-sensitive recording layer in the present invention includes fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, diacetone-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, and amide-modified with a degree of polymerization of 200 to 1900. Polyvinyl alcohol, sulfonic acid-modified polyvinyl alcohol, butyral-modified polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, styrene-maleic anhydride copolymer, styrene-butadiene copolymer, cellulose derivatives such as ethyl cellulose and acetyl cellulose, polyvinyl acetate , Polyacrylamide, polyacrylic acid ester, polyvinyl butyral polystyrene and its copolymers, polyamide resin, silicone resin, petroleum resin, terpene resin, ketone resin, chroman resin and the like. These binders can be used alone or in combination of two or more, and can be used by being dissolved in a solvent, or can be used in a state of being emulsified or dispersed in a paste in water or another medium.

Pigments to be blended in the heat-sensitive recording layer include silica, calcium carbonate, kaolin, calcined kaolin, keiso soil, talc, titanium oxide, zinc oxide, aluminum hydroxide, polystyrene resin, urea-formalin resin, and styrene-methacrylic acid co-weight. Examples thereof include inorganic or organic pigments such as coalesced, styrene-butadiene copolymers and hollow plastic pigments.

The types and amounts of basic dyes, color formers, sensitizers, binders, pigments and other additives used in the heat-sensitive recording layer in the present invention are appropriately determined according to the quality performance required for the heat-sensitive recording layer. It is determined.

In the heat-sensitive recording layer of the present invention, the content of the N-substituted amino acid derivative represented by the general formula (1) as a color developer is based on 1 part by mass of the basic dye of the heat-sensitive recording layer from the viewpoint of color development concentration. Therefore, 0.3 to 5 parts by mass is preferable, and 0.4 to 3 parts by mass is more preferable.

Further, the sensitizer is suitable for 0.2 to 4 parts by mass with respect to 1 part of the leuco dye, and the binder is suitable for 5 to 50% by mass in the total solid content. As the support, paper, recycled paper, synthetic paper, plastic film, non-woven fabric, metal foil and the like can be used. In addition, a composite sheet in which these are combined can also be used.

Further, an overcoat layer made of a polymer substance containing an organic pigment may be provided for the purpose of improving storage stability. Further, an undercoat layer containing an organic pigment, an inorganic pigment, hollow fine particles, or the like may be provided for the purpose of preventing the adhesion of dust to the thermal head, improving the print image quality, and improving the sensitivity.

The basic dyes, color formers, sensitizers and, if necessary, storage stabilizers used in the heat-sensitive recording layer in the present invention are averaged by a stirring pulverizer such as a ball mill, an attritor, or a sand mill using water as a dispersion medium. It is finely dispersed and used so that the particle size is 2 μm or less.
The heat-sensitive recording layer coating material is prepared by mixing and stirring a pigment, a binder, an auxiliary agent, etc., if necessary, in the finely dispersed dispersion liquid.
The heat-sensitive recording layer coating material thus obtained is applied onto the support so that ^{the coating amount after drying is about 1.5 to 12 g / m 2} , more preferably about 3 to 7 g / m ^2. , Formed by drying.

Hereinafter, the present invention will be specifically described 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".

An example of synthesis of the N-substituted amino acid derivative used in the examples is shown below.
Synthesis Example 1: N- (m-Phenylalaninecarbonyl) -Phenylalanine After charging 16.5 g of L-phenylalanine and 50 g of water in a four-necked flask equipped with a thermometer, a dropping funnel, and a stirrer, the internal temperature is 15 ° C. L-Phenylalanine was dissolved by adding 50 g of an 8% aqueous sodium hydroxide solution. The internal temperature was maintained at 15 ° C., 13.3 g of m-tolyl isocyanate dissolved in ethyl acetate was added dropwise, and the mixture was stirred for 5 hours. Ethyl acetate was added to the reaction mixture, neutralized with dilute hydrochloric acid, and the product was extracted with ethyl acetate. Ethyl acetate of the extract was concentrated, and then toluene was added to the concentrated residue for crystallization. The crystals were separated by filtration and dried to obtain N- (m-tolylaminocarbonyl) -phenylalanine as white crystals. The melting point was 151 ° C.

Synthesis Example 2: N- (m-trylaminocarbonyl) -methionine White crystals by the same operation as in Synthesis Example 1 except that 14.9 g of L-methionine is used instead of 16.5 g of L-phenylalanine in Synthesis Example 1. N- (m-tolylaminocarbonyl) -methionine was obtained. The melting point was 142 ° C.

Synthesis Example 3: N- (m-tolylaminocarbonyl) -valine By the same operation as in Synthesis Example 1, white crystals are obtained by the same operation as in Synthesis Example 1 except that 11.7 g of L-valine is used instead of 16.5 g of L-phenylalanine in Synthesis Example 1. N- (m-tolylaminocarbonyl) -valine was obtained. The melting point was 169 ° C.

Synthesis Example 4: N- (m-tolylaminocarbonyl) -tyrosine By the same operation as in Synthesis Example 1, white crystals are obtained by the same operation as in Synthesis Example 1 except that 18.1 g of L-tyrosine is used instead of 16.5 g of L-phenylalanine in Synthesis Example 1. N- (m-tolylaminosulfonyl) -tyrosine was obtained. The melting point was 161 ° C.

A thermal recording material was prepared by the following operation.

[Creation of paint for undercoat]
100 parts of plastic hollow particles (trade name: Low Pake SN-1055: hollow ratio: 55% solid content 26.5%), 100 parts of 50% dispersion of calcined kaolin, styrene-butadiene latex (trade name: L-1571 solid) (48%) 25 parts, 50 parts of a 10% aqueous solution of oxidized starch and 20 parts of water were mixed to prepare an undercoat paint.

(Example 1)
[Creation of paint for thermal recording]
Liquid A (preparation of dye dispersion)
3- (N, N-dibutylamino) -6-methyl-7-anilinofluorane 10 parts 10% polyvinyl alcohol aqueous solution 10 parts water 16.7 parts

Liquid B (preparation of color developer dispersion)
N- (m-trillaminocarbonyl) -methionine (color developer 2) 20 parts 10% polyvinyl alcohol aqueous solution 20 parts Water 33.3 parts

Liquid C (preparation of sensitizer dispersion)
1,2-bis (m-tolyloxy) ethane 15 parts 10% polyvinyl alcohol aqueous solution 15 parts water 25 parts

Liquid D (preparation of storage stabilizer dispersion)
5 parts of diphenylsulfone crosslinked compound represented by the following general formula (2)

(In the formula, n represents an integer of 1 to 7.)
10% polyvinyl alcohol aqueous solution 5 parts water 8.33 parts

The dispersions of solutions A, B, C and D were pulverized with a sand grinder until the average particle size became 1 μm or less, and the dispersions were mixed at the following ratios to prepare a coating solution.
Liquid A (dye dispersion) 36.7 parts Liquid B (color developer dispersion) 73.3 parts Liquid C (sensitizer dispersion) 55.0 parts Liquid D (storage stabilizer liquid) 18.33 parts

Aluminum hydroxide (trade name: Heidilite H-42 20 parts, amorphous silica (trade name: Mizukasil P-605) 10 parts, 10% solution of oxidized starch 20 parts, zinc stearate dispersion: (trade name:) A composition consisting of 15 parts of hydrin Z-8-36) and 20 parts of water was mixed to prepare a heat-sensitive recording paint.

[Creation of thermal recording material]
As a support, the undercoat paint is applied to high-quality paper (acid paper) having a basis weight of 53 g ^{so that the mass per area after drying is 6 g / m 2,} and then the heat-sensitive paint is applied to the dried area. The coating was applied and dried so that the contact mass was 3.5 g / m ^2.
This sheet was processed with a super calendar so that the smoothness (JIS P8155: 2010) was 900 to 1200 s to prepare a thermal recording material.

[Various tests]
1. 1. Thermal recordability test (color development test)
The prepared thermal recording material was applied with an applied energy of 0.38 mJ / dot using a thermal recording paper printing tester (TH-PMD manufactured by Okura Electric Co., Ltd.). The print density of the recording unit was measured with a Macbeth reflection densitometer RD-914.

2. Heat resistance test After leaving the heat-sensitive recording material recorded in the heat-sensitive recording test for 24 hours in a constant temperature environment at a test temperature of 60 ° C., the density of the printed part and the density of the unprinted part of the test piece were measured with a Macbeth reflection densitometer. ..

3. 3. Moisture resistance test After leaving the heat-sensitive recording material recorded in the heat-sensitive recording test for 24 hours in an environment with a test temperature of 40 ° C and 90% RH, the density of the printed part and the density of the unprinted part of the test piece are measured with a Macbeth reflection densitometer. It was measured.

4. Oil resistance test The heat-sensitive recording material recorded in the heat-sensitive recording test was immersed in salad oil for 1 minute, and then the oil of the test piece was wiped off, and the image density was measured with a Macbeth reflection densitometer.

5. Water resistance test The thermal recording paper recorded in the thermal recording property test was immersed in water for 24 hours, then the test piece was air-dried, and the image density and the unprinted portion were measured with a Macbeth reflection densitometer.

6. Plasticizer resistance test Wrap a wrap film (trade name: High Wrap KMA Mitsui Chemicals) on a polycarbonate pipe (48 mmφ) in three layers, place the heat-sensitive recording paper recorded in the heat-sensitive recordability test on it, and then place the wrap film on it. It was wrapped in three layers and left to stand in an environment of 20 ° C. and 65% RH for 24 hours, after which the image density and the unprinted portion were measured with a Macbeth reflection densitometer.

The results of various tests of the heat-sensitive recording material according to this example are as shown in Table 1.

(Example 2)
Same as Example 1 except that N- (m-tolylaminocarbonyl) -methionine (color developer 1) in Solution B of Example 1 is replaced with N- (m-toluenesulfonyl) -phenylalanine (color developer 2). Was performed.
The results of various tests of the heat-sensitive recording material according to this example are as shown in Table 1.

(Example 3)
Same as in Example 1 except that N- (m-tolylaminocarbonyl) -phenylalanine (color developer 1) in Solution B of Example 1 is replaced with N- (phenylaminocarbonyl) -methionine (color developer 3). The operation was performed.
The results of various tests of the heat-sensitive recording material according to this example are as shown in Table 1.

(Example 4)
Example 1 and Example 1 except that N- (m-tolylaminocarbonyl) -methionine (color developer 1) in solution B is replaced with N- (p-tolylaminocarbonyl) -methionine (color developer 4). The same operation was performed.
The results of various tests of the heat-sensitive recording material according to this example are as shown in Table 1.

(Example 5)
Example 1 except that N- (m-tolylaminocarbonyl) -methionine (color developer 1) in Solution B of Example 1 is replaced with N- (m-tolylaminocarbonyl) -valine (color developer 5)). The same operation as was performed.
The results of various tests of the heat-sensitive recording material according to this example are as shown in Table 1.

(Example 6)
Example 1 except that N- (m-tolylaminocarbonyl) -methionine (color developer 1) in Solution B of Example 1 is replaced with N- (m-tolylaminocarbonyl) -phenylglycine (color developer 6). The same operation as was performed. The results of various tests of the heat-sensitive recording material according to this example are as shown in Table 1.

(Example 7)
Example 1 and Example 1 except that N- (m-tolylaminocarbonyl) -methionine (color developer 1) in solution B is replaced with N- (m-tolylaminocarbonyl) -tyrosine (color developer 7). The same operation was performed. The results of various tests of the heat-sensitive recording material according to this example are as shown in Table 1.

[Comparative Example 1]
The same operation as in Example 1 was performed except that the D solution of Example 1 was not used. The results of various tests of the thermal recording material according to this comparative example are as shown in Table 1.

[Comparative Example 2]
The same operation as in Example 2 was performed except that the D solution of Example 2 was not used. The results of various tests of the thermal recording material according to this comparative example are as shown in Table 1.

[Comparative Example 3]
The same operation as in Example 3 was performed except that the D solution of Example 3 was not used. The results of various tests of the thermal recording material according to this comparative example are as shown in Table 1.

[Comparative Example 4]
The same operation as in Example 4 was performed except that the D solution of Example 4 was not used. The results of various tests of the thermal recording material according to this comparative example are as shown in Table 1.

[Comparative Example 5]
The same operation as in Example 5 was performed except that the D solution of Example 5 was not used. The results of various tests of the thermal recording material according to this comparative example are as shown in Table 1.

[Comparative Example 6]
The same operation as in Example 6 was performed except that the D solution of Example 6 was not used. The results of various tests of the thermal recording material according to this comparative example are as shown in Table 1.

[Comparative Example 7]
The same operation as in Example 7 was performed except that the D solution of Example 7 was not used. The results of various tests of the thermal recording material according to this comparative example are as shown in Table 1.

[Comparative Example 8]
The same operation as in Comparative Example 1 was carried out except that N- (m-tolylaminocarbonyl) -methionine (color developer 1) in Liquid B of Comparative Example 1 was replaced with bisphenol A (color developer 8). The results of various tests of the thermal recording material according to this comparative example are as shown in Table 1.

[Comparative Example 9]
The same operation as in Comparative Example 1 was performed except that N- (m-tolylaminocarbonyl) -methionine (color developer 1) in Solution B of Comparative Example 1 was replaced with 4,4'bisphenol S (color developer 9). rice field. The results of various tests of the thermal recording material according to this comparative example are as shown in Table 1.

As is clear from Table 1, the heat-sensitive recording material containing an amino acid derivative as a color developer and a diphenylsulfone-based crosslinked compound represented by the following general formula (2) as a storage stabilizer is good at high whiteness. In particular, Z is an OH group, X is -NHCO-, and N-substituted amino acid derivatives are N- (m-tolylaminocarbonyl) -phenylalanine and N- (m-tolylaminocarbonyl). In the case of -methionine, N- (m-tolylaminocarbonyl) -valine, N- (m-tolylaminocarbonyl) -phenylglycine and N- (m-tolylaminocarbonyl) -tyrosine, the heat-sensitive recording material produced is: In addition to showing good color density with high whiteness, storage stability such as heat resistance, moisture resistance, and oil resistance of printed and unprinted areas is also good, and a specific storage stabilizer should be added. Therefore, it can be used as a heat-sensitive recording material having excellent water resistance of the printed portion.

(In the formula, n represents an integer of 1 to 7.)

Since the color developer used in the heat-sensitive recording material of the present invention is mainly made of natural amino acids, there is no concern about endocrine disrupting, the color density is excellent, the whiteness of the non-printed portion is high, and printing is performed. Since the storage stability of the part is also good, its industrial applicability as an alternative to the conventional heat-sensitive recording material is extremely promising.

Claims (2)

A heat-sensitive recording material provided on a support with a heat-sensitive recording layer containing a basic dye that is colorless or light-colored at room temperature and a color-developing agent that can come into contact with the dye and develop a color by heating. The agents are N- (m-tolylaminocarbonyl) -phenylalanine, N- (m-tolylaminocarbonyl) -methionine, N- (p-tolylaminocarbonyl) -methionine, N- (phenylaminocarbonyl) -methionine, N- A heat-sensitive recording material that is at least one selected from the group consisting of (m-tolylaminocarbonyl) -valine, N- (m-tolylaminocarbonyl) -phenylglycine and N- (m-tolylaminocarbonyl) -tyrosine. A heat-sensitive recording material containing a diphenylsulfone crosslinked compound represented by the following general formula (2) as a storage stabilizer in the heat-sensitive recording layer.

(In the formula, n represents an integer of 1 to 7.) The content of the storage stabilizer, heat-sensitive recording material according to claim 1, characterized in that 2 to 100 parts by weight per 100 parts by weight color developer.