JPH0664323A - Thermal recording material - Google Patents

Abstract

(57) [Summary] [Structure] A primary amino group-containing compound selected from the group of aromatic primary amino compounds, salts of aromatic primary amino compounds, and metal complex salts of aromatic primary amino compounds, and the primary amino group-containing compounds A heat-sensitive recording material comprising a combination of a copper compound that develops a colorant, containing an amide compound represented by the following general formula (1) as a sensitivity improver. [R ¹ and R ² are each independently a hydrogen atom, an alkyl group,
It represents an aralkyl group or an aryl group which may have a substituent.] [Effect] The heat-sensitive recording material of the present invention has high color-developing sensitivity, good image storability and a wide range of absorption from the visible region to the near infrared region. It is possible to obtain an image having

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording material, and more specifically, it is selected from the group consisting of aromatic primary amino compounds, salts of aromatic primary amino compounds, and metal complex salts of aromatic primary amino compounds. A heat-sensitive recording material comprising a combination of a primary amino group-containing compound and a copper compound for coloring the primary amino group-containing compound, characterized by containing an amide compound represented by the following general formula (1) as a sensitivity improver. The present invention relates to a thermosensitive recording material.

[0002]

[Chemical 2]

[0003]

2. Description of the Related Art Thermal recording records information by utilizing a coloring phenomenon that occurs when a colorless or light-colored material is heated. Various types have been proposed to date. Has been done. Among them, the one that is currently in the mainstream is represented by the invention described in JP-B-45-14039, in which an electron-donating leuco dye is used as a color former, and this is used as an electron-accepting developer. It is a type that reacts to develop color. Many leuco dyes such as phthalides and fluoranes are known as leuco dyes used as color formers in this type of heat-sensitive recording material, and heat-sensitive recording materials using these can obtain clear recorded images with a simple device. Since it exhibits excellent recording characteristics in terms of color development sensitivity, etc., it has already gained wide demand. However, on the other hand, since these thermosensitive recording materials utilize the reversible reaction of leuco dyes, the color image gradually fades under a natural storage environment, or fades within a short period of time due to exposure or the like. Such unfavorable properties can be seen. Improvement of storability has been a long-standing issue for thermosensitive recording materials.

On the other hand, one of the usage forms of such a recording material, which has recently been in high demand, is an application to an automatic reading system of a recorded image by a machine. This is a system in which the difference in reflectance between the recorded portion and the non-recorded portion is read by mechanical means, converted into an electrical signal and directly input to a computer,
Some are called by CR (optical character reader), OMR (optical symbol reader) and the like. Although there are various types of light sources for such an automatic reading system for characters and symbols, it is advantageous to use a semiconductor laser from the viewpoint of low cost and light weight of the device. However, since the light from the conventional semiconductor laser is near infrared light,
To utilize this, a recording material having absorption in the near infrared region is required. However, the color images of many leuco dyes used from the beginning in thermal recording materials and still in use do not have near-infrared absorption, and OC using a semiconductor laser as a light source.
Not available for R system. To make a heat-sensitive recording material that can be used in such a system, for example, JP-A-59-59
It is necessary to use a special leuco dye that absorbs even in the near infrared region when it is colored, as described in JP-A-199757 and JP-A-62-243653. However, these leuco dyes for near-infrared absorption are expensive, and the color image has absorption only in the visible part, and since many of them have poor storage stability as compared with conventional leuco dyes, they are not so practical. It has not reached a big record.

Under such circumstances where a leuco dye is mainly used, a thermal recording material of a type using a metal complex compound has also been proposed. For example, U.S. Pat. No. 2,663,654 includes a type in which an organic acid iron compound and a polyhydric phenol compound as a ligand compound are reacted to form a metal complex compound for color development. Such a material has better stability of a color image as compared with the above-mentioned thermal recording material using a leuco dye. However, the extinction coefficient of a conventional color-forming substance composed of a metal complex compound is often smaller than that of an organic compound such as a leuco dye, and therefore the image often lacks sharpness. Further, compared to the above leuco dye type, the reaction at the time of heating is slow and the sensitivity is low, and the background coloring is likely to occur.

[0006]

DISCLOSURE OF THE INVENTION The present inventors have used a new type of recording material that can replace these known heat-sensitive recording materials, particularly, there is no problem of fading of a color image and use of near infrared light. As a result of various studies in order to develop a heat-sensitive recording material that can be used in an OCR system, it was found that a heat-sensitive color-developing system utilizing the reaction of an aromatic primary amino group-containing compound and a copper compound gives a highly storable recorded image and applied. (Japanese Patent Application No. 4-116633 and application dated July 8, 1992).

However, although this color-developing system has the advantage of high preservability, it has insufficient color-developing sensitivity, and as a result of continued research, in addition to these materials, the general formula (1) It was found that the addition of an amide compound represented by the formula drastically improves the color development sensitivity, and further research has led to the present invention.

Specific examples of the metal complex salt of an aromatic primary amino compound which serves as a color former in this color forming system include, for example, tri (o-phenylenediamine) zinc.bis (tetraphenylboronic acid) salt and tri (o-phenylene). Diamine) nickel bis (tetraphenyl boric acid) salt, bis (4-
Methyl-o-phenylenediamine) zinc bis (ter)
t-butylbenzoic acid) salt and the like, and examples of salts of a metal-free aromatic primary amino compound include 4-aminodiphenylamine bissalicylatoborate, 4′-methoxy-4-aminodiphenylamine bis ( 3,5-G-t
There are ert-butyl salicylatoborate and the like, and as the aromatic primary amino compounds constituting these salts and metal complex salts, there are the following as well.

4-aminodiphenylamine having no substituents or the following substituents; 2-methyl-, 2-ethyl-, 2-methoxy-, 2-ethoxy-, 2-n-propoxy-, 2 -N-butoxy-, 2-benzyloxy-, 2-chloro-, 2-carboxy-, 2-ethoxycarbonyl-, 2,3-dimethyl-, 2,5-dimethyl-, 2,5-dimethoxy-, 2 , 5-diethoxy-,
2,3,5,6-tetramethyl-, 3-methyl-, 3-
Methoxy-, 3-chloro-, 2,3-dichloro-, 4 '
-Methyl-, 4'-ethyl-, 4'-n-propyl-,
4'-n-butyl-, 4'-tert-butyl-, 4 '
-Cyclohexyl, 4'-n-octyl-, 4'-methoxy-, 4'-ethoxy-, 4'-propoxy-, 4 '
-N-butoxy-, 4'-n-octyloxy-, 4 '
-Benzyloxy-, 4'-benzoyl-, 4'-amino-, 4 '-(N-phenylamino)-, 4'-chloro-, 4'-bromo-, 4'-fluoro-, 2'-methyl -, 2,4'-dimethyl-, 3,4'-dimethyl-, 2
-Methyl-4'-methoxy-, 3-methyl-4'-methoxy-, 2'-methyl-4'-methoxy-, 3-chloro-4'-methoxy-, N-methyl-, N-ethyl-, N
-N-butyl-, N-cyclohexyl, Nn-octyl-, N-benzyl-, N-phenyl, N- (4-methoxyphenyl)-, N- (4-aminophenyl)-, N
-Methyl-4'-methyl-, N-methyl-4'-methoxy-, N- (4-aminophenyl) -4'-amino-.

1,4-Phenylenediamine having no substituents or the following substituents; 2-methyl-, 2,5-
Dimethyl-, 2,5-diethyl-, 2,5-dibutyl-, 2,3,5,6-tetramethyl-, 2,3,5,6
-Tetrafluoro-, 2-methoxy-, 2-butoxy-, 2,5-dimethoxy-, 2,5-diethoxy-,
2,5-dipropoxy-, 2,5-dicarboxy-,
2,5-di (methoxycarbonyl)-, 2-methylthio-, N-methyl-, N-ethyl-, N-benzyl-,
N, N-dimethyl-, N, N-diethyl-, N-acetyl-, N-benzoyl-.

1,2-phenylenediamine having no substituents or the following substituents; 4-methyl-, 4-ethyl-, 4-halogeno-, 4-methoxy-, 4-ethoxy-, 4-benzyl Oxy-, 4-methylthio-, 4-ethylthio-, 4-benzylthio-, 4-phenyl-, 4
-(4-methylphenyl)-, 4- (4-ethylphenyl)-, 4- (2-methylphenyl)-, 4-benzoyl-, 3-methyl-, 3-normalbutyl-, 3-halogeno-, 3-methoxy-, 3-ethoxy-, 3-benzyloxy-, 3-methylthio-, 3-phenyl-, 3-
(4-methylphenyl)-, 3- (2-methylphenyl)-, 3-benzoyl-, 3-nitro-, 3,4-dimethyl-, 4,5-dimethyl-, N-phenyl-, N-
(4-methylphenyl)-, N- (4-methoxyphenyl)-, N-methyl-, N, N-diphenyl-, N, N
-Dimethyl-.

1,3-phenylenediamine having no substituents or the following substituents; 4-methyl-, 4-ethyl-, 4-methoxy-, 2-ethoxy-, 2-propoxy-, 5-methoxy -, 5-normal butoxy-2,
5-dimethoxy-, 2,5-diethoxy-, 2-methylthio-, 2-ethylthio-, N-phenyl-, N-methyl-, N-ethyl-, N-benzyl-, N, N-diphenyl-, N , N-dimethyl-, N, N-diethyl-.

Anilines having no substituents or the following substituents; p-hydroxy-, p-methoxy-, p-ethoxy-, p-propoxy-, p-butoxy-, p-hexyloxy, p-octyl. Oxy-, p-benzyloxy-, p-methylthio-, p-benzylthio-, p-
Benzoyl-, p-phenyl-, p-nitro-, p-halogeno-, p-methyl-, p-ethyl-, p-butyl-, o-hydroxy-, o-methoxy-, o-ethoxy-, o- Mercapto-, o-methylthio-, o-ethylthio-, o-butylthio-, o-benzoyl-, o-phenyl-, o-halogeno-, o-methyl-, o-ethyl-, o-butyl-, o- Hexyl-, o-carboxy-, o-methoxycarbonyl-, m-hydroxy-, m
-Methoxy-, m-butoxy-, m-benzyloxy-, m-mercapto-, m-methylthio-, m-butylthio-, m-benzoyl-, m-phenyl-, m-halogeno-, m-butyl-, m-Butyl-, 2-chloro-4
-Methyl-, 2,3-dimethyl, 2,4-dimethyl-,
2,5-dimethyl-, 2,6-dimethyl-, 2,4-dimethoxy-, 2,5-dimethoxy-, 2,3-dichloro-, 2,4-dichloro-.

Further, 1,5-diaminonaphthalene,
There are 1,8-diaminonaphthalene, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone and the like.

Since the above-mentioned aromatic primary amino compounds are unstable in air, it is necessary to stabilize them by forming a salt or a metal complex salt. In addition to this, the aromatic primary amino compounds shown below are salts. It can be used without using metal complex salt. That is, 2,2'-diaminodiphenyl disulfide, 2,2'-diaminodiphenyl disulfide,
2,2'-diamino-4,4'-dimethyldiphenyl disulfide, 2,2'-diamino-5,5'-dimethyldiphenyl disulfide, 2,2'-diamino-5
5'-dichlorodiphenyl disulfide, 2,2'-diamino-4,4'-di (trifluoromethyl) diphenyl disulfide, 2,2'-diamino-4,4'-dicarboxydiphenyl disulfide, 2,2'- Diamino-4,4'-di (ethoxycarbonyl) diphenyl disulfide, 2,2'-diamino-4,4'-di (aminocarbonyl) diphenyl disulfide, 2,2'-diamino-5,5'-dimethoxydiphenyl disulfide ,
2,2'-diamino-5,5'-diethoxydiphenyldisulfide, 2,2'-diamino-4,4'-dibenzoyldiphenyldisulfide, 2,2'-diaminodiphenyltrisulfide, 2,2'-diamino Diphenyl tetrasulfide, 4,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl disulfide, 2,4'-diaminodiphenyl sulfide, 2,
4'-diaminodiphenyl disulfide, 2,3'-diaminodiphenyl disulfide, 3,3'-diaminodiphenyl disulfide and the like.

When the above-mentioned amino compound is used as a metal complex salt, it is preferable to use a colorless or light-colored complex compound. Therefore, the central metal is Zn, Ni, A.
Although metals such as g, Sn, Al, Ca, and Mg can be selected, Zn, Al, and Ni are often appropriate.

Further, as the anion serving as a counter ion (or ligand) when the above-mentioned amino compound is formed into a metal complex salt or a salt containing no metal, the following anions of acids can be mentioned. For example, hydrochloric acid, sulfuric acid, perchloric acid,
Tetrachloroboronic acid, tetrafluoroboric acid, tetraphenylboric acid, tetrakis (4-fluorophenyl) boric acid, tetrakis (4-chlorophenyl) boric acid, tetrakis [3,5-di (trifluoromethyl) phenyl] boric acid , Bissalicylatoboric acid, bis (3-methylsalicylato) boric acid, bis (4-methylsalicylato) boric acid, bis (5-methylsalicylato) boric acid, bis (3-phenylsalicylato) boric acid, bis (5- Chlorosalicylato) boric acid, bis (3,5-dichlorosalicylato) boric acid, bis (3,5-dihydroxysalicylato) boric acid, bis (3,5-dimethoxysalicylato) boric acid, bis (3 , 5-di-methylsalicylate) boric acid,
Bis (3,5-di-tert-butylsalicylate) boric acid, bis (3,5-di-α-methylbenzylsalicylate) boric acid, bis [3,5-di (α, α-dimethylbenzyl) salicylate ] Boric acid, bis (3-diphenylmethylsalicylate) boric acid, bis (5-diphenylmethylsalicylate) boric acid, bis (2-oxide-1-naphthato) boric acid, bis (2-oxide-3) -Naphthoato) boric acid, bis (1-oxide-2-naphthato) boric acid,
Biscatecholatoboric acid, bis (3,5-di-tert-
Butylcatecholato) boric acid, phenol, p-tert
-Butylphenol, p-phenylphenol, 2,2
-Bis (4-hydroxyphenyl) propane, 4,4 '
-Dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl sulfide, and organic acids as shown below.

Specific examples of the organic acid include stearic acid,
Palmitic acid, oleic acid, behenic acid, lauric acid, capric acid, caproic acid, valeric acid, isobutyric acid, butyric acid, propionic acid, acetic acid, formic acid, benzoic acid, o-toluic acid, m
-Toluic acid, p-toluic acid, p-tert-butylbenzoic acid, p-octylbenzoic acid, p-octyloxybenzoic acid, o-chlorobenzoic acid, m-chlorobenzoic acid,
p-chlorobenzoic acid, dichlorobenzoic acid, trichlorobenzoic acid, p-bromobenzoic acid, p-iodobenzoic acid, p
-Phenylbenzoic acid, o-benzoylbenzoic acid, p-nitrobenzoic acid, anthranilic acid, p-aminobenzoic acid,
Oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, phthalic acid monoester, terephthalic acid,
Terephthalic acid monomethyl ester, terephthalic acid monoethyl ester, terephthalic acid monobutyl ester, naphthenic acid, 1-naphthoic acid, 2-naphthoic acid, tartaric acid, diphenylamine-2-carboxylic acid, 4-cyclohexylbutyric acid, diethyldithiocarbamic acid, gluconic acid , Octylic acid, p-toluenesulfonic acid, n-dodecylbenzenesulfonic acid, dodecylsulfate, α-naphthylphosphoric acid, stearylphosphoric acid, laurylphosphoric acid, di-2-ethylhexylphosphoric acid, isodecylphosphoric acid, salicylic acid, o-cresotic acid 3,5-dimethylsalicylic acid, 3,5-di-
Mention may be made of tert-butylsalicylic acid, 3,5-di-α-methylbenzylsalicylic acid, 3,5-di (α, α-dimethylbenzyl) salicylic acid, 3-diphenylmethylsalicylic acid, 5-chlorosalicylic acid and the like.

Further, as the copper compound, there are those represented by the following general formula (2), in addition to those having the same anions as those listed above as counter ions (or ligands).

[0020]

[Chemical 3]

Examples of the compound of the general formula (2) include those having a substituent as shown in Tables 1 and 2 below.
In Tables 1 and 2, Ph means a phenyl group.

[0022]

[Table 1]

[0023]

[Table 2]

In addition to this, the copper complex compound represented by the general formula (2) includes a compound in which A ² and A ³ are linked to each other to form a ring, and examples thereof include methyl salicylate, benzyl salicylate, and 1-hydroxy-. Phenyl 2-naphthoate, salicylaldehyde, 1-hydroxy-2-naphthaldehyde, 2-hydroxy-1-naphthaldehyde, 2-hydroxy-3-naphthaldehyde, 2-hydroxyacetophenone, 2-hydroxybenzophenone, 2-hydroxy- Examples of the copper complex include 4-n-octyloxybenzophenone, dehydroacetic acid, α-acetyl-γ-butyrolactone, and the like as ligands.

The amide compounds represented by the general formula (1) which serve as a sensitivity improver in the color forming system of the present invention are as follows. That is, acetamide, propionamide, butyramide, balearinamide, capronamide, heptaneamide, caprinamide, oleic acid amide, stearic acid amide, palmitic acid amide, acetanilide, 2-methylacetanilide, 3-methylacetanilide, 4-methylacetanilide, 2-ethylacetanilide, 3-ethylacetanilide, 4-ethylacetanilide, 2-propylacetanilide, 3-propylacetanilide, 4-propylacetanilide,
2-methoxyacetanilide, 3-methoxyacetanilide, 4-methoxyacetanilide, 2-ethoxyacetanilide, 3-ethoxyacetanilide, 4-ethoxyacetanilide, 2-chloroacetanilide, 3-chloroacetanilide, 4-chloroacetanilide, 2-
Acetoxyacetanilide, 3-acetoxyacetanilide, 4-acetoxyacetanilide, 4-aminoacetanilide, 2,5-dimethoxyacetanilide, 2,
4-dimethoxyacetanilide, N-benzoyl-o-
Phenetidine, benzamide, 4-methoxybenzamide, 3-methoxybenzamide, 2-methoxybenzamide, 4-aminobenzamide, 3-aminobenzamide, 2-aminobenzamide, benzanilide, N-acetylbenzylamine, N-acetylcyclohexylamine, N, Examples thereof include N-diphenylformamide and N, N-diphenylacetamide.

In order for the above amide compound to function as a sensitivity improver, the melting point is preferably in the range of 50 ° C to 200 ° C, more preferably 70 ° C to 15 ° C.
It should be in the range of 0 ° C. When each substance alone is not within its melting point range, especially when they have a high melting point, it is possible to adjust the melting point by falling by mixing two or more kinds of substances. .

When the above-mentioned amide compound is added to the heat-sensitive recording layer, the addition amount is not particularly limited as long as it dissolves the color former component upon heating, but is preferably a primary amino group-containing compound. 10% to 3 with respect to the weight of
Used in the range of 00%.

The method for producing the heat-sensitive recording material of the present invention is not particularly limited, but usually, a homogeneous liquid obtained by dispersing or dissolving the material in the form of fine particles in water or an organic solvent is coated on a suitable support. The method of drying after that is taken. Paper is generally used as the support in that case, but synthetic paper, plastic, rubber, metal, or a composite material thereof can also be used. As the binder for adhering the recording layer and the support, a high molecular compound such as a polyvinyl compound or a cellulosic compound can be used, and various additives can be added for the purpose of improving appearance and recording characteristics. For example, wax for improving surface characteristics and thermal head matching, inorganic pigments,
Addition of a metal salt or the like, addition of an antioxidant for increasing recording stability, an ultraviolet absorber, a singlet oxygen quencher, and the like. It is also possible to add a protective layer such as a polymer substance on the coated surface.

Further, known leuco dyes as exemplified below may be added for the purpose of adjusting the hue and the coloring sensitivity. For example, crystal violet lactone, 2-chloro-6-diethylaminofluorane, 3-chloro-6
-Cyclohexylaminofluorane, 2-dibenzylamino-6-diethylaminofluorane, 2-anilino-
3-methyl-6-diethylaminofluorane, 2-anilino-3-methyl-6-dibutylaminofluorane, 2
-Anilino-3-methyl-6-dipentylaminofluorane, 2-anilino-3-methyl-6- (N-ethyl-
N-isopentylamino) fluorane, 2-anilino-
3-Methyl-6- (N-ethyl-N-p-tolylamino) fluorane, 2-o-chloroanilino-6-dibutylaminofluorane, 2-o-chloroanilino-6-
(N-ethyl-N-hexylamino) fluorane and the like.

[0030]

EXAMPLES Next, the present invention will be specifically described with reference to examples. Here, "parts" means "parts by weight". Example 1 1) Preparation of color developer dispersion (solution A) Bis (ethylacetoacetate) copper 1 part Calcium carbonate 1.5 parts 5% polyvinyl alcohol aqueous solution 7.5 parts Paint shaker (Toyo Seiki Co., Ltd.) (Manufactured by Seisakusho) for 60 minutes. 2) Preparation of color developer dispersion (solution B) 4-aminodiphenylamine bis (3,5-di-t-butylsalicylate) borate 1 part 5% aqueous solution of polyvinyl alcohol 9 parts The above mixture was ground for 60 minutes with a paint shaker. did. 3) Preparation of sensitizer dispersion liquid (C liquid) Stearic acid amide 1 part 10% polyvinyl alcohol aqueous solution 9 parts 4) Preparation and coating of heat-sensitive coating liquid A liquid 1, liquid B 1 part, liquid C 1 part After mixing and stirring, this coating liquid was uniformly applied to paper with a wire bar so that the coating amount after drying was 6 g / m ^2, and dried to obtain a thermosensitive recording paper. When this paper was pressed with a hot plate heated to 120 ° C. for 1 second, a clear black colored image was obtained. This image has not only visible absorption but also near-infrared absorption.
It was recognizable by the R device. This color image is light, heat,
It was stable against contact with water and fats and oils, and was left outdoors for 1 week and exposed to sunlight, but there was no change. Again 30
% Ethanol solution was applied for 10 hours, but there was no change.

Example 2 In the preparation of solution A of Example 1, copper p-chlorobenzoate was used in place of bis (ethylacetoacetate) copper, and in preparation of solution B, 4-aminodiphenylamine bis (3,3) was used.
5′-Methoxy-4-aminodiphenylamine bis (3,5-di-t-butylsalicylate) borate was used in place of 5-di-t-butylsalicylate) borate, and otherwise the same as in Example 1. A thermosensitive recording paper was obtained. When this was pressed with a hot plate heated to 120 ° C. for 1 second, a color image with black color and near infrared absorption was obtained. This color-developed image was stable to light, heat, contact with water, oils and fats, etc., and was left outdoors for 1 week and exposed to sunlight, but there was no change. Also, when it was immersed in a 30% aqueous ethanol solution for 10 hours, there was no change.

Examples 3 to 20 In the preparation of the liquid C of Example 1, the compounds shown in Table 3 below were used in place of stearic acid amide, and the other examples were used.
A thermosensitive recording paper was obtained in the same manner as in (1). When this was pressed with a hot plate heated to 120 ° C. for 1 second, all black and near-infrared absorption color images were obtained, and they were stable against contact with light, heat, water, oils and fats.

[0033]

[Table 3]

Example 21 In the preparation of the solution B of Example 1, 2,2'-diaminodiphenyl was used instead of 4'-methoxy-4-aminodiphenylamine bis (3,5-di-t-butylsalicylat) borate. A thermosensitive recording paper was obtained in the same manner as in Example 1 except that disulfide was used. When this was pressed with a hot plate heated to 120 ° C. for 1 second, a color image with black color and near infrared absorption was obtained. It was stable to light, heat, contact with water, oils and fats.

Comparative Examples 1 to 9 In the preparation of the liquid C of Example 1, the compounds shown in Table 4 below were used in place of stearic acid amide, and the other examples were used.
A thermosensitive recording paper was obtained in the same manner as in (1).

[0036]

[Table 4]

Comparative Example 10 A thermosensitive recording paper was obtained in the same manner as in Example 1 except that the solution C was not used in the preparation of the thermosensitive coating solution of Example 1 and only 1 part of the solution A and 1 part of the solution B were mixed. It was

Comparative Example 11 A thermosensitive recording paper was obtained in the same manner as in Example 2, except that the C solution was not used in the preparation of the heat-sensitive coating solution of Example 2 and only 1 part of the solution A and 1 part of the solution B were mixed. It was

Comparative Example 12 In the preparation of the heat-sensitive coating liquid of Example 21, the liquid C was used and the liquid A was used.
A thermosensitive recording paper was obtained in the same manner as in Example 21, except that 1 part of the liquid and 1 part of the B liquid were mixed.

Comparative Example 13 In the preparation of solution A of Example 1, bisphenol A was used in place of bis (ethylacetoacetate) copper, and in preparation of solution B, 4-aminodiphenylamine bis (3,5-
A thermosensitive recording paper was obtained in the same manner as in Example 1 except that 2-anilino-3-methyl-6-dibutylaminofluorane was used in place of (di-t-butylsalicylate) borate. When this was pressed with a hot plate heated to 160 ° C. for 1 second, a black colored image was obtained, but there was no near infrared absorption in this image. Further, when this image area was left outdoors for 1 week and exposed to sunlight, remarkable discoloration was observed, and when the image area was immersed in a 30% ethanol aqueous solution for 1 hour, the image completely disappeared.

Coloring Test The thermal papers obtained in the examples and comparative examples were applied with a thermal line printer (manufactured by Okura Electric Co., Ltd.) at an applied voltage of 18 V and pulse widths of 1.5, 2.0, 2.5, 3. Color was changed for 5 milliseconds, and the reflection density of this color image was measured with a Macbeth reflection densitometer RD-514 (filter: Ratten # 106). The results are shown in Tables 5 and 6.

[0042]

[Table 5]

[0043]

[Table 6]

[0044]

As described above, the heat-sensitive recording material of the present invention has high color-developing sensitivity, good image storability, and an image having a wide range of absorption from the visible region to the near infrared region can be obtained. It has high utility value as various recording materials including applications.

Front page continuation (72) Inventor Tomoyuki Shinden 1 1 Kamitaba Kamitochocho, Minami-ku, Kyoto City Yamada Chemical Industry Co., Ltd. (72) Inventor Toshiro Naritsuka 1 1 Kamitabacho, Minami-ku, Kyoto City 1 Yamada Chemical Industry Co., Ltd.

Claims (1)

[Claims] 1. A primary amino group-containing compound selected from the group of aromatic primary amino compounds, salts of aromatic primary amino compounds, and metal complex salts of aromatic primary amino compounds, and copper for coloring the primary amino group-containing compound. A heat-sensitive recording material comprising a combination of compounds, which comprises an amide compound represented by the following general formula (1) as a sensitivity improver. [Chemical 1]