JP2000296678A - Heat sensitive recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance preserving characteristics of an image portion and particularly oil resistance and to further improve heat resistance of a base portion by laminating a heat sensitive color developing layer containing a leuco dye and a developer made of a specific aromatic carboxylic acid compound for color developing the dyed when heated as main components on a support. SOLUTION: The heat sensitive recording material is formed by providing a heat sensitive color developing layer containing a leuco dye and a developer for color developing the dye when heated as main components on a support. In this case, as the developer, an aromatic carboxylic acid compound represented by the formula (wherein X is a bivalent group derived from a carbonyl group, a sulfonyl group or a an aliphatic hydrocarbon, a bivalent group derived from an aliphatic hydrocarbon containing one or above heteroatom, carbonyl group, sulfonyl group or aromatic ring in a main chain, or a bivalent group derived from one or above heteroatom, a carbonyl group or two aromatic hydrocarbons bonded by an aliphatic hydrocarbon containing a hetero compound in a main chain.) is used.

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 having excellent image storability.

[0002]

2. Description of the Related Art A thermosensitive recording material generally comprises a support provided with a thermosensitive coloring layer mainly comprising an electron-donating colorless or light-colored dye precursor and an electron-accepting developer. By heating with a head, hot pen, laser light, etc.,
The dye precursor and the developer react instantaneously, and a recorded image is obtained.
It is disclosed in, for example, Japanese Patent Publication No. 14039. Such a heat-sensitive recording material has advantages such that recording can be obtained with a relatively simple device, maintenance is easy, and noise is less generated.In recent years, computers, facsimile machines, ticket vending machines, label printers, It is used in a wide range of fields as recording materials for recorders and the like. However, a heat-sensitive recording material using such an electron-donating dye precursor and an electron-accepting color developer has excellent properties such as good appearance, good touch, and high color density, The recorded image area comes into contact with plastics such as polyvinyl chloride, etc., and is easily discolored by plasticizers and additives contained in plastics, or comes into contact with chemicals contained in foods and cosmetics, etc. In addition, there was a disadvantage that the storage stability as a recording material was inferior, for example, the recorded image portion was erased or the background portion was colored.

As a means for achieving high storage stability of a recorded image, use of a highly reliable color developer has been conventionally proposed. For example, JP-A-58-82788, JP-A-60-82
A phenol sulfone compound is proposed in JP-A-13852, and a substituted salicylic acid compound is proposed in JP-A-62-169681. However, when these compounds are used as a color developer, the image portion has fastness to a plasticizer. It is not enough in terms of sex.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a heat-sensitive recording material having high preservability in an image area, particularly excellent oil resistance of an image and heat resistance of a background.

[0005]

According to the present invention, first, there is provided a thermosensitive recording layer having, on a support, a thermosensitive coloring layer mainly composed of a leuco dye and a developer for developing the leuco dye upon heating. The present invention provides a heat-sensitive recording material characterized by using a compound represented by the following general formula (I) as the color developer.

Embedded image (Wherein X is a carbonyl group, a sulfonyl group, a divalent group derived from an aliphatic hydrocarbon, one or more heteroatoms in the main chain, a carbonyl group, a sulfonyl group, an ester bond,
A divalent group derived from an aliphatic hydrocarbon containing an aromatic ring, one or more heteroatoms, a carbonyl group, a sulfonyl group, an ester bond, an alkylene, or an aliphatic hydrocarbon containing a heteroatom in the main chain; It shows any of the divalent groups derived from two linked aromatic hydrocarbons. )

Secondly, in the above-mentioned first thermal recording, the functional group X in the general formula (I) is any of groups derived from a divalent aliphatic hydrocarbon. Materials are provided.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The reason why the heat-sensitive recording material using the compound represented by the general formula (I) has high oil resistance and high heat resistance is not clear, but it is considered that the following factors generally contribute. Aromatic carboxylic acids, which are strong acids substituted with electron-withdrawing groups, have the ability to develop color. When two or more aromatic carboxylic acids are contained in one molecule, the molecular weight increases, and the solubility in nonvolatile solvents such as oils and plasticizers decreases.

The aromatic carboxylic acid compound represented by the general formula (I) is a completely novel compound. These compounds are
For example, it is possible to synthesize by the following route. In this case, usually, a mixture of compounds (isomers) having different carboxyl group substitution positions can be obtained. When these compounds are used as a developer for a thermosensitive recording material, they are used as a mixture of isomers. be able to. Further, if necessary, the isomers can be separated and purified and used as a single product.

Embedded image (The above route shows an outline of the esterification and etherification, and the protection, hydrolysis, etc. necessary in the actual synthesis are omitted. Y is a leaving group such as a halogen atom. Is shown.)

In the present invention, as described above, the compound represented by the general formula (I) is used as a color developer. Here, specific examples of X in the general formula (I) include alkylene having 1 to 16 carbon atoms, oxyalkylene, bisoxyalkylene, trisoxyalkylene, oxoalkylene, bisoxoalkylene, trisoxoalkylene,
Thioalkylene, bisthioalkylene, tristhioalkylene, sulfinylalkylene, bissulfinylalkylene, trissulfinylalkylene, sulfonylalkylene, bissulfonylalkylene, trissulfonylalkylene, hydroxyalkylene, bishydroxyalkylene, trishydroxyalkylene, sulfonyldioxyalkylene, bis Sulfonyldioxyalkylene, trissulfonyldioxyalkylene, carbonyldioxyalkylene, biscarbonyldioxyalkylene, triscarbonyldioxyalkylene, carbamoylalkylene, biscarbamoylalkylene, triscarbamoylalkylene, and divalent represented by the following formula Functional groups.

Embedded image

Embedded image

In the above formula, R may be of different types;
A hydrogen atom, a halogen atom, an alkyl group having 1 to 8 carbon atoms, an aralkyl group, or an aryl group;
Indicates an integer of 4.

Specific examples of A in the above formula include the following. C1-C16 alkylene, oxyalkylene, bisoxyalkylene, trisoxyalkylene, oxoalkylene, bisoxoalkylene, trisoxoalkylene, thioalkylene, bisthioalkylene, tristhioalkylene, sulfinylalkylene, bissulfinylalkylene, trissulfinyl Alkylene, sulfonylalkylene, bissulfonylalkylene, trissulfonylalkylene, hydroxyalkylene, bishydroxyalkylene, trishydroxyalkylene, sulfonyldioxyalkylene, bissulfonyldioxyalkylene, trissulfonyldioxyalkylene, carbonyldioxyalkylene, biscarbonyldioxy Alkylene, triscarbonyldioxyalkylene, carbamoylal Ren, bis carbamoyl alkylene, tris carbamoyl alkylene.

Specific examples of B in the above formula include the following. Direct bond (when there is no functional group), oxygen atom, carbonyl group, sulfur atom, sulfinyl group, sulfonyl group, sulfonyloxy group, carbonyloxy group, carbonylamino group, urea group, hydrazinocarbonyl group, hydrazinosulfonyl group , Phenylene, biphenylene, xylylene,

Embedded image

Embedded image C1-C16 alkylene, oxyalkylene, bisoxyalkylene, trisoxyalkylene, oxoalkylene, bisoxoalkylene, trisoxoalkylene, thioalkylene, bisthioalkylene, tristhioalkylene, sulfinylalkylene, bissulfinylalkylene, trissulfinyl Alkylene, sulfonylalkylene, bissulfonylalkylene, trissulfonylalkylene, hydroxyalkylene, bishydroxyalkylene, trishydroxyalkylene,
Sulfonyldioxyalkylene, bissulfonyldioxyalkylene, trissulfonyldioxyalkylene,
Carbonyldioxyalkylene, biscarbonyldioxyalkylene, triscarbonyldioxyalkylene,
Carbamoylalkylene, biscarbamoylalkylene, triscarbamoylalkylene.

Specific examples of the compound represented by the general formula (I) of the present invention include the following.
The present invention is not limited to these.

[0014]

[Table 1]

[0015]

[Table 2]

The basic dye precursor (leuco dye) used in the present invention can be used alone or as a mixture of two or more kinds. As such a leuco dye, those applied to a heat-sensitive material can be used. It can be used arbitrarily, and examples thereof include the following. 3,3-
Bis (p-dimethylaminophenyl) phthalide, 3,3
-Bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3-diethylamino-6-methyl-7
-Anilinofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 3-N-methyl-N-butylamino-6-methyl-7-anilinofluoran,
-N-methyl-N-propylamino-6-methyl-7-
Anilinofluoran, 3-N-ethyl-N-propylamino-6-methyl-7-anilinofluoran, 3-N-
Methyl-N-amylamino-6-methyl-7-anilinofluoran, 3-N-ethyl-N-amylamino-6-
Methyl-7-anilinofluoran, 3-N-ethyl-N
-Isoamylamino-6-methyl-7-anilinofluoran, 3-N-hexyl-N-isoamylamino-6-
Methyl-7-anilinofluoran, 3-N-methyl-N
-Cyclohexylamino-6-methyl-7-anilinofluoran, 3-N-ethyl-N-furanylmethylamino-6-methyl-7-anilinofluoran, 3-diethyl-N-butylamino-7- (2'-fluoroanilino)
Fluoran, 3-pyrrodilyl-7-dibenzylaminofluoran, 3-bis (diphenylamino) fluoran,
3-diethylamino-7- (2'-chloroanilino) fluoran, 3-diethylamino-6-chloro-7-anilinofluoran, 3-dibutylamino-7- (2'-chloroanilino) fluoran, 3-diethylamino-7-
Chlorofluorane, 3-diethylamino-6-methyl-
7-chlorofluorane, 3-N-methyl-N-cyclohexylamino-6-chlorofluoran, 3-diethylamino-6-methyl-7- (2 ', 4'-dimethylanilino) fluoran, 3-diethylamino- 7-dibenzylaminofluoran, 3-butylamino-7- (2'-chloroanilino) fluoran, 3-diethylamino-6
Ethoxyethyl-7-anilinofluoran and the like.

In the present invention, in addition to being used alone as a color developer, it can be used in combination with a conventionally known color developer and used for other purposes such as a sensitizer.
Specific examples of conventionally known color developers used at that time include the following. 4,4'-isopropylidenebisphenol, 4,4'-isopropylidenebis (o
-Methylphenol), 4,4'-sec-butylidenebisphenol, 4,4'-isopropylidenebis (2
-Tert-butylphenol), zinc p-nitrobenzoate, 1,3,5-tris (4-tert-butyl-3)
-Hydroxy-2,6-dimethylbenzyl) isocyanuric acid, 2,2- (3,4-dihydroxyphenylpropane), bis (4-hydroxy-3-methylphenylsulfide), 4- (β- (p- Methoxyphenoxy) ethoxy) salicylic acid, 1,7-bis (4-hydroxyphenylthio) -3,5-dioxaheptane, monobenzyl phthalate monocarboxylic acid, 4,4′-cyclohexylidenebisphenol, 4,4′-isopropylidenebis (2-chlorophenol), 2,2′-methylenebis (4-methyl-6-tert-butylphenol)
4,4'-butylidenebis (6-tert-butyl-2-methyl) phenol, 1,1,3-tris (2
-Methyl-4-hydroxy-5-cyclohexyl) butane, 4,4'-thiobis (6-tert-butyl 2-methylphenol) 4,4'-diphenolsulfone,
-Benzyloxy-4'-hydroxydiphenylsulfone, 4-isopropyloxy-4'-hydroxydiphenylsulfone, 4,4'-diphenolsulfoxide,
Isopropyl p-hydroxybenzoate, benzyl p-hydroxybenzoate, benzyl protocatechuate, stearyl gallate, 1,3-bis (4-hydroxyphenylthio) propane, 1,3-bis (4-hydroxyphenylthio) -2 -Hydroxypropane, N, N-diphenylthiourea, N, N-di (m-chlorophenylthiourea), salicylanilide, 5-chlorosalicylanilide, bis (4-hydroxyphenyl) acetic acid methyl ester, bis (4-hydroxy Phenyl) acetic acid benzyl ester, 1,3-bis (4-hydroxycumyl) benzene, 1,4-bis (4-hydroxycumyl) benzene,
2,4'-diphenol sulfone, 2,2'-diallyl-4,4'-diphenol sulfone, 3,4-dihydroxy-4'-methyldiphenyl sulfone, α, α-bis (4-hydroxyphenyl)- α-methyltoluene,
4,4′-thiobis (2-methylphenol), 4,
4'-thiobis (2-chlorophenol) and the like.

In the present invention, various heat-fusible substances can be used alone or as a mixture of two or more kinds as a sensitivity improver and a lubricant. Specific examples include the following. 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; Benzylbiphenyl, terphenyl, triphenylmethane, benzyl p-benzyloxybenzoate, β-benzyloxynaphthalene, phenyl β-naphthoate, phenyl 1-hydroxy-2-naphthoate, methyl 1-hydroxy-2-naphthoate, Diphenyl carbonate, benzyl terephthalate, 1,4-dimethoxynaphthalene, 1,4-diethoxynaphthalene, 1,4-dibenzyloxynaphthalene,
1,2-diphenoxyethane, 1,2-bis (4-methylphenoxyethane), 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) biphenyl, p-aryloxybiphenyl, dibenzoyloxymethane, dibenzoyloxypropane, dibenzyldisulphide, 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, bis (4-chlorobenzyl) oxalate and the like.

In preparing the heat-sensitive recording material of the present invention, in addition to the above-described color developer, leuco dye, and heat-fusible substance, various materials commonly used for forming the heat-sensitive recording material are used. It can be used as appropriate. Examples thereof include binders for binding various materials on a support or the like in the heat-sensitive recording layer, and these can be used alone or in combination of two or more. Are as follows. Polyvinyl alcohol, modified polyvinyl alcohol, starch and derivatives thereof, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, cellulose derivatives such as ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide / acrylate copolymer, acrylamide / acrylic acid Ester / methacrylic acid terpolymer, styrene / maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, polyacrylamide, modified polyacrylamide, methyl vinyl ether / maleic anhydride copolymer, Carboxy-modified polyethylene, polyvinyl alcohol / acrylamide block copolymer, melamine-formaldehyde resin, urea-formaldehyde De resins, sodium alginate, gelatin, water-soluble polymer such as casein,
Polyvinyl acetate, polyurethane, styrene / butadiene copolymer, styrene / butadiene / acrylic copolymer, polyacrylic acid, polyacrylate, polymethacrylate, vinyl chloride / vinyl acetate copolymer, polybutyl methacrylate, Emulsions such as polyvinyl butyral, polyvinyl acetal, and ethylene / vinyl acetate copolymer are exemplified. These may be used alone or as a mixture, and may be further cured by adding a crosslinking agent (curing agent) as needed. The crosslinking agent (curing agent) in this case reacts with the binder, and examples thereof include a glyoxal derivative, a methylol derivative, an epichlorohydrin derivative, an epoxy compound, and an aziridine compound.

Specific examples of the pigment used alone or in combination of two or more in the heat-sensitive recording material include the following. Inorganic fine powders such as silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, kaolin, calcined kaolin, talc, and surface-treated silica. Organic fine powders such as urea-formalin resin, styrene / methacrylic acid copolymer, polystyrene resin, vinylidene chloride resin, styrene / acrylic copolymer, and plastic hollow hollow fine particles.

Further, the heat-sensitive recording material of the present invention may optionally contain a pigment, a binder, a crosslinking agent, a lubricant, etc. on the heat-sensitive coloring layer for the purpose of improving the head matching property and the writing property on the recording material. It is possible to provide a protective layer as a component,
In this case, as the pigment, binder, crosslinking agent, and lubricant, the above-described pigment, binder, crosslinking agent, and lubricant (a heat-fusible substance) can be used alone or in combination of two or more.

In the present invention, the above-mentioned general formula (I)
When the compound represented by the formula (1) is used in the thermosensitive coloring layer, the content thereof is 1 to 10 g / m ² by dry weight, preferably 1 to 10 g / m ² .
５5 g / m ² is appropriate.

In the present invention, an undercoat layer containing a pigment, a binder and the like as main components can be provided between the support and the thermosensitive coloring layer. The undercoat layer functions as a heat insulating layer, and improves sensitivity by efficiently utilizing thermal energy from a thermal head or the like. As the pigment and the binder constituting the undercoat layer, the above-mentioned pigments and binders can be used alone or in combination of two or more. In this case, it is desirable to use plastic spherical hollow fine particles as the pigment.

The above-mentioned "plastic spherical hollow fine particles" are fine hollow particles which have a thermoplastic resin as a shell, contain air or other gas therein, and are already in a foamed state, and have an average particle diameter of 0. 0.2 to 20 μm. If the average particle diameter (particle diameter) is smaller than 0.2 μm, there is a problem in production such as difficulty in obtaining an arbitrary hollow ratio, and there is a problem in cost.
When the particle size is larger than m, the surface smoothness after coating and drying is reduced, so that the adhesion to the thermal head is reduced and the effect of improving the thermal sensitivity is reduced. Therefore, it is preferable that the particles have a particle diameter in the above-mentioned range and a small variation in the particle diameter.

Further, in consideration of the heat insulating effect, the plastic spherical hollow particles preferably have a hollow ratio of 40% or more, more preferably 90% or more. When the hollow ratio is low, the heat energy from the thermal head is released to the outside of the heat-sensitive recording material through the support because the heat insulating effect is insufficient, and the effect of improving the thermal sensitivity is poor. Here, the "hollow ratio" is a ratio of the outer diameter to the inner diameter of the hollow fine particles, and is represented by the following formula. Hollow ratio (%) = (inner diameter of hollow fine particles) / (outer diameter of hollow fine particles) × 100

As described above, the plastic hollow spherical fine particles have a shell made of a thermoplastic resin. Examples of the resin include polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyacrylate, and polyacrylate. Examples thereof include acrylonitrile, polybutadiene, and copolymer resins thereof. Among these, a copolymer resin mainly containing vinylidene chloride and acrylonitrile is particularly preferable.

In the present invention, the binder resin used for forming the undercoat layer is appropriately selected from conventionally known water-soluble polymers and / or aqueous polymer emulsions. Specific examples thereof include, as water-soluble polymers, for example, polyvinyl alcohol, starch and derivatives thereof, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose,
Cellulose derivatives such as ethyl cellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide / acrylate copolymer, acrylamide / acrylate / methacrylic acid terpolymer, styrene / maleic anhydride copolymer alkali salt, isobutylene / Maleic anhydride copolymer alkali salt, polyacrylamide,
Examples include sodium alginate, gelatin, casein and the like. Examples of the aqueous polymer emulsion include latexes such as styrene / butadiene copolymer and styrene / butadiene / acrylic copolymer, vinyl acetate resin, vinyl acetate / acrylic acid copolymer, and styrene / acrylic ester copolymer. And emulsions of acrylate resin, polyurethane resin and the like.

In the undercoat layer, together with the hollow fine particles and the binder resin, if necessary, auxiliary additives commonly used in this type of heat-sensitive recording material, for example, fillers, heat-fusible substances, A surfactant, a pressure coloring inhibitor and the like can be used in combination. In this case, specific examples of the filler and the heat-fusible substance include those described above in relation to the heat-sensitive coloring layer component.
When plastic spherical hollow fine particles are used for the undercoat layer, other inorganic pigments can be added for the purpose of improving the matching property with the thermal head.

Incidentally, a layer containing a pigment, a binder, a heat-fusible substance and the like can be provided as an intermediate layer between the undercoat layer and the thermosensitive coloring layer, if necessary. Furthermore,
The heat-sensitive recording material of the present invention improves the head matching property at the time of printing, improves the storage stability of the recorded image, and improves the writing property on the recording material and the printing property.
It is also possible to provide a protective layer on the thermosensitive coloring layer. In this case, as the components constituting the protective layer, the above-mentioned filler, binder resin, heat-fusible substance and the like can be used.

In the heat-sensitive recording material of the present invention, a back layer mainly composed of a pigment, a binder, a crosslinking agent and the like can be provided on the back surface of the support. Also in this case, the above-mentioned pigments, binders, and lubricants (thermally fusible substances) are used as pigments, binders, and lubricants.

As a support of the heat-sensitive recording material of the present invention,
In addition to ordinary paper (acidic paper, neutral paper), it is possible to arbitrarily use one that can be applied and processed, for example, synthetic paper,
Polymer films and the like can be mentioned.

The heat-sensitive recording material of the present invention can be used in any field where a heat-sensitive recording material is conventionally used. Specific examples include facsimile paper, food POS labels, industrial barcode labels, linerless labels, ticket paper, magnetically attached paper, CAD paper, and transparent sensitivity films.

[0033]

Next, the heat-sensitive recording material of the present invention will be described in more detail with reference to examples. The following parts and percentages are all based on weight.

Synthesis Example 1 (Synthesis of Compound of Specific Example No. 1) 4- (2-hydroxyethoxy) benzoic acid 4 was placed in a reaction vessel.
5.5 g (0.25 mol), trimellitic anhydride 5
7.1 g (0.30 mol), triethylamine
9 g (0.90 mol) of tetrahydrofuran (TH
F) The mixture was suspended and charged in a mixture of 150 g and 50 g of dimethylformamide, and reacted at about 83 ° C. for 3 hours under reflux of the solvent. After cooling, 100 ml of water was added dropwise to the reaction mixture,
The mixture was stirred for about 30 minutes, and dilute hydrochloric acid was added dropwise until the pH became 2 or less. The two layers were separated by standing, and the organic layer was washed with water until crystallization occurred to obtain 91.5 g of white crystals (yield 98).
%). The product was a mixture of two structural isomers, the combined purity of which was 97.7% (HPLC) and the melting point was 258.
° C and ¹ H-NMR analysis indicated that it was the desired compound. The NMR spectrum is shown below. δ (ppm) = 13.20 (broad s), 8.25 (1
H, d), 8.16 (1H, d), 7.87 (3H,
d), 7.05 (2H, d), 4.48 (4H, broad
s).

Example 1 A mixture having the following composition was dispersed in a magnetic ball mill [A
Solution] to [Solution E]. [Solution A] 3-N, N-dibutylamino-6-methyl-7-anilinofluoran 10 parts 10% aqueous solution of polyvinyl alcohol 10 parts Water 30 parts [Solution B] Compound 1 1 part 10% aqueous solution of polyvinyl alcohol 10 parts Water 30 parts [Solution C] P527 (silica gel manufactured by Mizusawa Chemical) 10 parts 10% aqueous solution of polyvinyl alcohol 10 parts Water 30 parts [Solution D] Zinc stearate 10 parts 10% polyvinyl Aqueous alcohol solution 10 parts Water 30 parts Next, a mixture of the following composition was stirred and dispersed with a disper to prepare solution E. [E Solution] Non-foamable plastic micro hollow particles (solid content: 24%, average particle size: 3 μm, hollowness: 90%) 40 parts Styrene / butadiene copolymer latex 10 parts Water 50 parts Next, [A liquid]-[ E solution] to prepare a thermosensitive coloring layer coating solution and an undercoat coating solution at the following mixing ratio. (Thermosensitive coloring layer coating solution) [Solution A]: [Solution B]: [Solution C]: [Solution D] = 1: 4:
4: 0.5 (undercoat coating solution) [Solution E]: [Solution C] = 2: 1 <Coating of each layer> The undercoat coating solution was applied to the surface of commercially available high quality paper (basis weight 60 g / m ² ). ) Having a dry weight of 3 g / m ²
And dried to obtain an intermediate coated paper (paper coated with an undercoat layer). On the undercoat layer, the coating weight of the thermosensitive coloring layer was adjusted to a dry weight of 0.5 g / m ² of leuco dye.
Was applied and dried to provide a thermosensitive coloring layer. Thereafter, calendering was performed at a pressure of 10 kg / cm ² to obtain a heat-sensitive recording material of the present invention.

Comparative Example 1 In the case of the specific example No. In place of the compound of 1, 2,2-bis (4-hydroxyphenyl)
Example 1 except that propane (bisphenol A) was used
And a thermosensitive recording material was obtained.

The following test was performed on the heat-sensitive recording material prepared as described above. Table 3 shows the results. <Color development test> Head power of 0.68 W / d by a simulator printing experiment apparatus having a thin film head manufactured by Matsushita Parts Corporation.
ot, pulse width 0.9 ms under conditions of 1 line recording time 10 ms / line, scanning line density 8 × 3.85 dots / mm
After printing with cottonseed oil on the obtained printed image portion, the image density after standing at 40 ° C. for 15 hours was measured with a Macbeth densitometer to evaluate oil resistance. In addition, 8 similar test pieces
The surface density after standing for 15 hours in an environment of 0 ° C. and 100 ° C. was measured with a Macbeth densitometer to evaluate heat resistance.

[0038]

[Table 3] From the results in Table 3, it is clear that the heat-sensitive recording material of the present invention is excellent in oil resistance of an image and heat resistance of a background.

[0039]

Since the heat-sensitive recording material of the present invention has a heat-sensitive coloring layer using the compound represented by the formula (I) as a color developer, it has excellent heat resistance of images and heat resistance of the background. It is a thing.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Kunio Hayakawa, 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Ikuo Kameoka 4-231-1, Bunkyo, Fukui-shi, Fukui Nichika (72) Inventor Yang Konan 4-23-1, Bunkyo, Fukui-shi, Fukui Prefecture F-term in Nichika Chemical Co., Ltd. 2H026 AA07 BB01 BB37

Claims (2)

[Claims] 1. A thermosensitive recording material having a thermosensitive coloring layer comprising, as a main component, a leuco dye and a developer for developing the leuco dye upon heating on a support, wherein the developer is represented by the following general formula (I) A heat-sensitive recording material characterized by using the compound represented by the formula (1). Embedded image (Wherein X is a carbonyl group, a sulfonyl group, a divalent group derived from an aliphatic hydrocarbon, one or more heteroatoms in the main chain, a carbonyl group, a sulfonyl group, an ester bond,
A divalent group derived from an aliphatic hydrocarbon containing an aromatic ring, one or more heteroatoms, a carbonyl group, a sulfonyl group, an ester bond, an alkylene, or an aliphatic hydrocarbon containing a heteroatom in the main chain; It shows any of the divalent groups derived from two linked aromatic hydrocarbons. ) 2. In the general formula (I), a functional group X
Is a group derived from a divalent aliphatic hydrocarbon.