JP3341089B2 - Thermal recording material - Google Patents

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 particularly, to a heat-sensitive recording material having remarkably improved image stability against an oil or a plasticizer.

[0002]

2. Description of the Related Art Generally, a thermosensitive recording material mainly comprises a colorless system comprising a colorless or pale-colored dye as a color former on a support such as paper, synthetic paper, plastic film and the like, and a color developer which develops the color when heated. And a colored image can be obtained by heating with a hot pen, a thermal head, a laser beam, a strobe lamp or the like. Compared to other recording materials, this recording material enables recording to be performed in a short time with a relatively simple device without performing complicated processing such as development and fixing, has less noise and environmental pollution, and has a lower cost. Due to its advantages such as cheapness, it is used for copying books, documents, etc., electronic calculators, facsimile ticket vending machines,
It is useful as various recording materials such as labels and recorders.

As a color-forming dye used for a heat-sensitive recording material, for example, a colorless or light-colored leuco dye having a lactone, lactam or spiropyran ring has been used, and a phenolic compound has been conventionally used as a developer. Recording materials using this color former and developer are widely used because of their high image density and high whiteness of the background.

However, an image formed by such a leuco dye and a phenolic color developer has poor storage stability because the color development is a reversible process. Will fade.
Further, there is a disadvantage that an image is easily discolored even when it comes into contact with water, oil, a plasticizer, or the like. In order to enhance the storage stability of such leuco dye-based color images, various studies have been made on color developers. For example, Japanese Patent Application Laid-Open No. 57-199686 proposes to improve the plasticizer resistance by using a benzophenone derivative having a sulfonyl group. However, such a sulfonic acid type developer is used in a non-image area. It is hard to say that it is practically poor in storage stability.

JP-A-59-185693 proposes a method of improving the plasticizer resistance by using a metal salt of an aromatic carboxylic acid and an aliphatic carboxylic acid. Its coloring properties are not sufficient and it is hard to say that it is practical. In JP-A-63-45087, a sulfonium compound is used, and in JP-A-1-294,884, a sulfonium compound of a type having a benzyl group as one of the substituents and an aromatic ammonium organic acid salt are used as a developer. There has been proposed a heat-sensitive recording material in which image stability with respect to a plasticizer is improved and coloration of a non-image portion is prevented by an organic solvent. It is considered that such a type of developer generates a cation species such as a benzyl cation due to thermal decomposition upon heating to form an electron-donating leuco dye.

However, such a thermal decomposition process requires a considerable amount of thermal energy, so that the heat source used for ordinary thermal recording has poor color developability and cannot be said to be practical. Also, JP-A-59-109388 and JP-A-Hei.
Japanese Patent Publication No. 178489 proposes to use a sulfonic acid ester derivative as a color developer, but its coloring property and image strength are hardly sufficient and cannot be said to be practical. Further, Japanese Patent Application Laid-Open No. 1-178489 proposes that by using a developer in which a hydrogen bond molecular complex is formed between bisphenol A and another phenolic compound or an amine compound, a plasticizer is improved as well as color development. However, in such a system, since a phenolic compound such as bisphenol A acts as a color developer, the plasticizer in the image is not fundamentally improved and is not practical. It is.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-sensitive recording material in which the storability of a color image and a non-image area, particularly the image stability with respect to oils and plasticizers, is remarkably improved. .

[0008]

According to the present invention, there is provided a thermosensitive recording material comprising a support and a thermosensitive coloring layer comprising, as a main component, a leuco dye and a developer which causes the leuco dye to develop a color when heated. As a developer, at least the following general formula (I)
There is provided a heat-sensitive recording material characterized by using an organic sulfonate compound of a benzimidazole derivative represented by the following formula (1).

Embedded image (Wherein, R ₁ represents a hydrogen atom, an alkyl group, a substituted alkyl group, an aryl group, a halogen atom, a nitro group or a carboxyl group, and R ₂ represents a hydrogen atom, an alkyl group, a substituted alkyl group, an aryl group, an alkoxy group, Thioether group,
A hydroxy group, a mercapto group, a guanidyl group, a pyridyl group, a halogen atom or an amino group, X represents a hydrogen atom or an alkyl group, and n is an integer of 1-4. According to the present invention, there is provided a thermosensitive recording material comprising a support having thereon a thermosensitive coloring layer mainly composed of a leuco dye and a developer capable of developing the leuco dye upon heating. A heat-sensitive recording material characterized by using an organic sulfonate compound of a benztriazole derivative represented by the formula (II) is provided.

Embedded image (Wherein, R ₃ represents a hydrogen atom, an alkyl group, a substituted alkyl group, an aryl group, a halogen atom, a nitro group or a carboxyl group, Y represents a hydrogen atom or a hydroxy group ,
m is an integer of 1 to 4. )

In the present invention, the organic sulfonate compounds of the benzimidazole derivative [general formula (I)] and the benztriazole derivative [general formula (II)] used as the color developing agent are those wherein the benzimidazole derivative or the benztriazole derivative is an organic compound. Rather than some complexes or mere mixtures that have intermolecular interactions with sulfonic acids, the protons of the organic sulfonic acids are bound to the lone pair of the heterocyclic nitrogen atom of the benzimidazole or benztriazole derivative. And a salt in which an organic sulfonate ion exists as a counter ion. This means that in the infrared absorption spectra of these compounds, the absorption specific to N—H of the tertiary amine salt was 2700 cm.
^It can be deduced from the fact that it is observed near ^-1 .

In the present invention, the organic sulfonate compound of a benzimidazole derivative and a benztriazole derivative used as a color developer is obtained by mixing an organic solvent solution of a benzimidazole derivative and a benztriazole derivative with an organic solvent solution of an organic sulfonic acid. The crude product obtained by the reaction can be purified by recrystallization from an appropriate solvent. As an example, a method for synthesizing an α-naphthalenesulfonic acid salt of benzimidazole will be described below. Benzimidazole (10 g, 0.0
8 mol) of acetone solution of α-naphthalenesulfonic acid (17 g, 0.08 mol) is added dropwise.
After the addition, the α-naphthalenesulfonate of benzimidazole is obtained as a milky white precipitate (25 g, 0.076 mol, 90% yield). By recrystallizing this precipitate from nitromethane, white crystals having a melting point of 168 to 170 ° C are obtained.

In the present invention, the organic sulfonate compound of the benzimidazole derivative and the benztriazole derivative used as a color developer can release a proton to a leuco dye upon heating to form a color. Therefore, when the compound of the present invention is used as a developer, an image which is hardly faded by an oil or a plasticizer can be obtained unlike the case where a general phenol-based developer is used.

In the present invention, specific examples of benzimidazole derivatives and benztriazole derivatives capable of forming a color developer (salt) with an organic sulfonic acid include the following, and the present invention relates to these. It is not limited.

<Benzimidazole derivatives> Benzimidazole, 5-benzimidazole carboxylic acid, 2-benzimidazole acetonitrile, 2-chloromethylbenzimidazole, 5-chloro-2-trichloromethylbenzimidazole, 5,6-dimethylbenzimidazole, 2-guadininobenzimidazole, 2-hydroxybenzimidazole, 2-mercaptobenzimidazole, 2-mercapto-5-methylbenzimidazole, 2-mercapto-5-nitrobenzimidazole,
2-methylbenzimidazole, 5-methylbenzimidazole, 2-methylmercaptobenzimidazole,
2-methyl-5-nitrobenzimidazole, 1-methyl-2-phenylbenzimidazole, 5-nitrobenzimidazole, 2-phenylbenzimidazole,
-(2-pyridyl) benzimidazole, 2-aminobenzimidazole, 2-amino-5,6-dimethylbenzimidazole,

<Benztriazole derivatives> Benztriazole, benzotriazole-5-carboxylic acid, 5,
6-dimethyl-1H-benztriazole, 1-hydroxybenztriazole, 5-methyl-1H-benztriazole, 5-nitrobenztriazole, allyl-
1-benztriazole carbonate.

Further, the above-mentioned benzimidazole derivative and
Benztriazole derivatives and color developers(salt)To form
Specific examples of the sulfonic acid include the following.
IsYou.  <Organic sulfonic acid> α-naphthalenesulfonic acid, β-naphthalenesulfonic acid, benzenesulfonic acid, and paratoluenesulfonic acid.

The leuco dyes used in the present invention may be used alone or as a mixture of two or more. As such leuco dyes, those applied to this type of recording material may be arbitrarily applied. Leuco compounds such as phenylmethane phthalide, triallyl methane, fluoran, phenothidian, thioferoral, methine, rhodamine anilinolactam, rhodamine lactam, quinazoline, diazaxanthene, and bislactone are preferably used. Can be Examples of such compounds include, for example, those shown below.

3,3-bis (p-dimethylaminophenyl)-
Phthalide, 3,3-bis (p-dimethylaminophenyl) -6
-Dimethylaminophthalide (also known as crystal violet lactone), 3,3-bis (p-dimethylaminophenyl)
-6-diethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) -6-chlorophthalide, 3,3-bis (p-
Dibutylaminophenyl) phthalide, 3-cyclohexylamino-6-chlorofluoran, 3-dimethylamino-5,
7-dimethylfluoran, 3-N-methyl-N-isobutyl-6-
Methyl-7-anilinofluoran, 3-N-ethyl-N-isoamyl-6-methyl-7-anilinofluoran, 3-diethylamino-7-chlorofluoran, 3-diethylamino-7-methylfluoran, 3-diethylamino-7,8-benzfluoran, 3-diethylamino-6-methyl-7-chlorofluoran, 3- (N-p-tolyl-N-ethylamino) -6-
Methyl-7-anilinofluoran, 3-pyrrolidino-6-
Methyl-7-anilinofluoran, 2- {N- (3'-trifluoromethylphenyl) amino} -6-diethylaminofluoran, 2- {3,6-bis (diethylamino) -9- (o-
(Chloranilino) xanthyl lactam lactam｝, 3-diethylamino-6-methyl-7- (m-trichloromethylanilino) fluoran, 3-diethylamino-7- (o-chloroanilino) fluoran, 3-dibutylamino-7- (o -Chloroanilino) fluoran, 3-N-methyl-N-amylamino-6-methyl-7-anilinofluoran, 3-N-methyl-N
-Cyclohexylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7- (2 ', 4'-dimethylanilino ) Fluoran, 3- (N, N-diethylamino) -5
-Methyl-7- (N, N-dibenzylamino) fluoran, benzoylleucomethylene blue, 6'-chloro-8'-methoxy-benzoindolino-spiropyran, 6'-bromo-
3'-methoxy-benzoindolino-spiropyran, 3-
(2′-hydroxy-4′-dimethylaminophenyl) -3-
(2′-methoxy-5′-chlorophenyl) phthalide, 3- (2 ′
-Hydroxy-4'-dimethylaminophenyl) -3- (2 '
-Methoxy-5'-nitrophenyl) phthalide, 3- (2'-
(Hydroxy-4'-diethylaminophenyl) -3- (2'-
Methoxy-5'-methylphenyl) phthalide, 3- (2'-methoxy-4'-dimethylaminophenyl) -3- (2'-hydroxy-4'-chloro-5'-methylphenyl) phthalide, 3
-Morpholino-7- (N-propyl-trifluoromethylanilino) fluoran, 3-pyrrolidino-7-trifluoromethylanilinofluoran, 3-diethylamino-5-chloro-7- (N-benzyl-trifluoromethyl (Anilino) fluoran, 3-pyrrolidino-7- (di-p-chlorophenyl)
Methylaminofluoran, 3-diethylamino-5-chloro-
7- (α-phenylethylamino) fluoran, 3- (N-ethyl
-p-Toluidino) -7- (α-phenylethylamino) fluoran, 3-diethylamino-7- (o-methoxycarbonylphenylamino) fluoran, 3-diethylamino-5-methyl-7-
(α-phenylethylamino) fluoran, 3-diethylamino-7-piperidinofluoran, 2-chloro-3- (N-methyltoluidino) -7- (pn-butylanilino) fluoran, 3-
(N-methyl-N-isopropylamino) -6-methyl-7-anilinofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 3,6-bis (dimethylamino) fluorenespiro ( 9,3 ′)-6′-dimethylaminophthalide, 3- (N-benzyl-N-cyclohexylamino) -5,6-benzo-7-α
-Naphthylamino-4'-bromofluoran, 3-diethylamino-6-chloro-7-anilinofluoran, 3-N-ethyl-N
-(2-ethoxypropyl) amino-6-methyl-7-anilinofluoran, 3-N-ethyl-N-tetrahydrofurfurylamino-6-methyl-7-anilinofluoran, 3-diethylamino
-6-methyl-7-mesitidino-4 ', 5'-benzofluoran, 3-
(p-dimethylaminophenyl) -3- {1,1-bis (p-dimethylaminophenyl) ethylene-2-yl} phthalide, 3- (p-dimethylaminophenyl) -3- {1,1-bis ( p-dimethylaminophenyl) ethylene-2-yl} -6-dimethylaminophthalide,
3- (p-dimethylaminophenyl) -3- (1-p-dimethylaminophenyl-1-phenylethylene-2-yl) phthalide, 3- (p-
Dimethylaminophenyl) -3- (1-p-dimethylaminophenyl-1-p-chlorophenylethylene-2-yl) -6-dimethylaminophthalide, 3- (4'-dimethylamino-2'-methoxy)-
3- (1 ''-p-dimethylaminophenyl-1 ''-p-chlorophenyl-1 '', 3 ''-butadiene-4 ''-yl) benzophthalide, 3-
(4'-Dimethylamino-2'-benzyloxy) -3- (1 ''-p-dimethylaminophenyl-1 ''-phenyl-1 '', 3 ''-butadiene-4 ''-yl) benzophthalide , 3-dimethylamino-6-dimethylamino-fluorene-9-spiro 3 ′ (6′-dimethylamino) phthalide, 3,3-bis {2- (p-dimethylaminophenyl) -2- (p-methoxyphenyl) ) Ethenyl} -4,5,6,7-tetrachlorophthalide, 3-bis {1,1-bis (4-pyrrolidinophenyl) ethylene-2-yl} -5,6-dichloro-4,7- Dibromophthalide, bis (p-dimethylaminostyryl) -1-naphthalenesulfonylmethane, bis (p-dimethylaminostyryl) -1
-p-tolylsulfonylmethane and the like.

In the present invention, the above-mentioned organic sulfonate compounds of the benzimidazole derivative and the benztriazole derivative are used as a color developer, but if necessary, another color developer can be used in combination. As the developer used in combination in this case, various compounds having electron accepting properties, for example, phenolic compounds, thiophenolic compounds, thiourea derivatives, organic acids and metal salts thereof can be used. Examples include, but are not limited to:

4,4'-isopropylidenebisphenol,
4,4′-isopropylidenebis (o-methylphenol),
4,4′-secondary butylidenebisphenol 4,4′-isopropylidenebis (2-tert-butylphenol), 4,4′-cyclohexylidenediphenol,
4,4′-isopropylidenebis (2-chlorophenol),
2,2'-methylenebis (4-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 4,4'-butylidenebis
(6-tert-butyl-2-methylphenol), 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'-thiobis ( 6-tert-butyl-2-methylphenol),
4,4′-diphenolsulfone, 4-isopropoxy-4′-hydroxydiphenylsulfone, 4-benzyloxy-4′-hydroxydiphenylsulfone, 4,4′-diphenolsulfoxide, isopropyl P-hydroxybenzoate, P -Benzyl hydroxybenzoate, benzyl protocatechuate, stearyl gallate, lauryl gallate, octyl gallate, 1,7-bis (4-hydroxyphenylthio) -3,
5-dioxaheptane, 1,5-bis (4-hydroxyphenylthio) -3-oxapentane, 1,3-bis (4-hydroxyphenylthio) -propane, 1,3-bis (4-hydroxyphenylthio ) -2-Hydroxypropane, N, N′-diphenylthiourea, N, N′-di (m-chlorophenyl) thiourea, salicylanilide, 5-chloro-salicylanilide, 2-hydroxy-3-naphthoic acid, 2 -Hydroxy-1
-Naphthoic acid, 1-hydroxy-2-naphthoic acid, metal salts of hydroxynaphthoic acid such as zinc, aluminum and calcium, bis- (4-hydroxyphenyl) acetic acid methyl ester, bis- (4-hydroxyphenyl) acetic acid benzyl ester , 1,3-bis (4-hydroxycumyl) benzene, 1,4
-Bis (4-hydroxycumyl) benzene, 2,4'-diphenolsulfone, 3,3'-diallyl-4,4'-diphenolsulfone, α, α-bis (4-hydroxyphenyl) -α- Methyltoluene, antipyrine complex of zinc thiocyanate,
Tetrabromobisphenol A, tetrabromobisphenol S, 4,4'-thiobis (2-methylphenol), 4,4'-
Thiobis (2-chlorophenol) and the like.

In order to produce the heat-sensitive recording material of the present invention,
When the leuco dye and the developer are bound and supported on the support, various conventional binders can be appropriately used, and specific examples thereof include the following.

Polyvinyl alcohol, starch and derivatives thereof, hydroxymethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, cellulose derivatives such as methyl cellulose, ethyl cellulose, etc .; -Da, polyvinylpyrrolidone, acrylamide / acrylate copolymer, acrylamide / acrylate / methacrylic acid terpolymer, styrene /
Maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, casein and other water-soluble polymers, polyvinyl acetate, polyurethane, polyacrylic acid, Polyacrylate, vinyl chloride / vinyl acetate copolymer, polybutyl methacrylate, ethylene /
Emulsions such as vinyl acetate copolymers and latexes such as styrene / butadiene copolymers and styrene / butadiene / acrylic copolymers.

In the present invention, various heat-fusible substances can be used as a sensitivity improver, and specific examples thereof include the following, but are not limited thereto. . Fatty acids such as stearic acid and behenic acid, fatty acid amides such as stearic acid amide and palmitic acid amide, fatty acid metal salts such as zinc stearate, aluminum stearate, calcium stearate, zinc palmitate and zinc behenate, p-benzyl Biphenyl, terphenyl, triphenylmethane, benzyl p-benzyloxybenzoate, β-benzyloxynaphthalene, phenyl β-naphthoate, phenyl 1-hydroxy-2-naphthoate, methyl 1-hydroxy-2-naphthoate, diphenyl Carbonate, gliacol carbonate, dibensil terephthalate, dimethyl terephthalate, 1,4-dimethoxynaphthalene, 1,4-diethoxynaphthalene, 1,4-dibenzyloxynaphthalene, 1,2-diphenoxyethane, 1,2 -
Bis (3-methylphenoxy) ethane, 1,2-bis (4-methylphenoxy) ethane, 1,4-diphenoxy-2-butene, 1,2-
Bis (4-methoxyphenylthio) ethane, dibenzoylmethane, 1,4-diphenylthiobutane, 1,4-diphenylthio
2-butene, 1,3-bis (2-vinyloxyethoxy) benzene, 1,4-bis (2-vinyloxyethoxy) benzene, p- (2
-Vinyloxyethoxy) bifer, p-aryloxyphenyl, p-propargyloxybiphenyl, dibenzoyloxymethane, dibenzoyloxypropane, dibenzyldisulfide, 1,1-diphenylethanol, 1,1-diphenylpropanol, p -Benzyloxybenzyl alcohol, 1,3-phenoxy-2-propanol, N-octadecylcarbamoyl-p-methoxycarbonylbenzene, N-
Octadecylcarbamoylbenzene, 1,2-bis (4-methoxyphenoxy) propane, 1,5-bis (4-methoxyphenoxy) -3-oxapentane, dibenzyl oxalate, bis (4-methylbenzyl) oxalate, oxalic acid Bis (4-chlorobenzyl) and the like.

When a heat-sensitive recording material is obtained according to the present invention, if necessary, together with a leuco dye, a developer and the compound of the present invention, additional components commonly used in this type of heat-sensitive recording material, such as fillers and surfactants Agents and the like can be used in combination. In this case, as a filler, for example, calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide,
Inorganic fine powders such as barium sulfate, clay, kaolin, talc, surface-treated calcium and silica, and urea
Examples include organic fine powders such as formalin resin, styrene-methacrylic acid copolymer, polystyrene resin, and vinylidene chloride resin. Further, regarding the layer structure, a single layer or a multilayer may be used, and if necessary, an over layer,
An under layer and a back layer can be provided.

[0024]

Next, the present invention will be described in more detail with reference to examples. The parts and percentages shown below are based on weight.

Example 1 The following mixtures were pulverized with a magnetic ball mill for 2 days to prepare [Solution A], [Solution B] and [Solution C]. [Solution A] 3- (N-methyl-N-cyclohexamino) -6-methyl-7-anilinofluoran 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts Water 60 parts [Solution B] Developer: benzimidazole α-Naphthalene sulfonate 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts Water 60 parts [Solution C] Silica 20 parts 5% aqueous solution of methylcellulose 20 parts Water 60 parts Next, [Solution A] 10 parts, [Solution B] 30 parts, [C solution] 30
Parts and 20% of isobutylene / maleic anhydride copolymer
10 parts of an aqueous alkali solution is mixed to form a thermosensitive coloring layer forming solution, which is coated on high-quality paper having a basis weight of 50 g / m ² and dried so that the dye adhesion amount after drying is 0.5 / m ² , followed by drying and thermosensitive coloring. After the layer was provided, the surface was further calendered to prepare the heat-sensitive recording material of Example 1.

Example 2 The procedure of Example 1 was repeated, except that the α-naphthalenesulfonate of benzimidazole, which was the developer of [Solution B], was replaced with p-toluenesulfonate of 5-methylbenzimidazole. A heat-sensitive recording material of Example 2 was prepared in the same manner as in Example 1.

Example 3 Example 1 was the same as Example 1 except that the α-naphthalenesulfonate of benzimidazole, which is the developer of [Solution B], was replaced with α-naphthalenesulfonate of benztriazole. In the same manner, a heat-sensitive recording material of Example 3 was prepared.

Example 4 In Example 1, α-naphthalenesulfonate of benzimidazole, which is a developer of [Solution B], was replaced with p-toluenesulfonate of 5-methyl-1H-benztriazole. A heat-sensitive recording material of Example 4 was prepared in the same manner as in Example 1 except for the above.

Comparative Example 1 In Example 1, the α-naphthalenesulfonic acid salt of benzimidazole which is a developer of [Solution B] was added to 4,4′-
Example 1 except that isopropylidene diphenol was used.
In the same manner as in Example 1, a heat-sensitive recording material of Example 1 was prepared.

Comparative Example 2 The procedure of Example 1 was repeated, except that the α-naphthalenesulfonate of benzimidazole, which was the developer of [Solution B], was replaced with benzyl p-hydroxybenzoate.
In the same manner as in the above, a heat-sensitive recording material of Comparative Example 2 was prepared.

Comparative Example 3 The procedure of Example 1 was repeated, except that the α-naphthalenesulfonate of benzimidazole, which was a developer of [Solution B], was replaced with a compound of the following structural formula (a) (formula 3). In the same manner as in Example 1, a heat-sensitive recording material of Comparative Example 3 was prepared.

Embedded image

The heat-sensitive recording materials of Examples 1 to 4 and Comparative Examples 1 to 3 obtained as described above were subjected to a temperature of 150 ° C. and a pressure of 2 kg / c using a thermal gradient tester (manufactured by Toyo Seiki Seisaku-sho, Ltd.).
m ² , printing was performed under the conditions of 2 seconds, and the image density and background density were measured using a Macbeth densitometer RD-914 (filter: W-10).
Measured in 6). Next, the samples after printing were tested for oil resistance and plasticizer resistance as follows. Table 1 shows the results. In addition, the density measurement after each of the above-mentioned storage tests was also performed using a Macbeth densitometer RD-914 (filter: W-106). Oil resistance: The density of the image area was measured after applying cottonseed oil to the printed area and storing it for 16 hours under a drying condition at a temperature of 40 ° C. Plasticizer resistance: Plasticizer (dioctyl adipate,
DOA) was applied to the printed area, and the density of the image area was measured after storage for 16 hours under a drying condition of 40 ° C.

[0033]

[Table 1] From Table 1, it can be seen that the heat-sensitive recording material of the present invention is extremely excellent in that the image area is not faded by an oil or a plasticizer.

[0034]

According to the present invention, in a thermosensitive recording material having a thermosensitive coloring layer mainly composed of a leuco dye and a developer capable of developing the leuco dye upon heating, the coloring material is used as a developer. By using at least one organic sulfonate compound of a benzimidazole derivative or a triazole derivative having a specific structure, the thermal stability of the color image and the non-image area, particularly the image stability to oil and plasticizer, is significantly improved. The material is obtained.

──────────────────────────────────────────────────の Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B41M 5/30

Claims (2)

(57) [Claims] 1. A thermosensitive recording material comprising a support having thereon a thermosensitive coloring layer mainly comprising a leuco dye and a developer capable of developing the leuco dye upon heating, wherein at least the following general formula (I) A) a thermosensitive recording material, which comprises using an organic sulfonate compound of a benzimidazole derivative represented by the following chemical formula (1). Embedded image (Wherein, R ₁ represents a hydrogen atom, an alkyl group, a substituted alkyl group, an aryl group, a halogen atom, a nitro group or a carboxyl group, and R ₂ represents a hydrogen atom, an alkyl group, a substituted alkyl group, an aryl group, an alkoxy group, Thioether group,
A hydroxy group, a mercapto group, a guanidyl group, a pyridyl group, a halogen atom or an amino group, X represents a hydrogen atom or an alkyl group, and n is an integer of 1-4. ) 2. A thermosensitive recording material comprising a support having thereon a thermosensitive coloring layer mainly composed of a leuco dye and a developer capable of developing the leuco dye upon heating, wherein at least the following general formula (II) A) a heat-sensitive recording material using an organic sulfonate compound of a benzotriazole derivative represented by the following chemical formula (2). Embedded image (Wherein, R ₃ represents a hydrogen atom, an alkyl group, a substituted alkyl group, an aryl group, a halogen atom, a nitro group or a carboxyl group, Y represents a hydrogen atom or a hydroxy group ,
m is an integer of 1 to 4. )