JP2003011519A - Heat-sensitive recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-sensitive recording material which is highly sensitive and almost free from a texture fog and further, shows superiority in terms of the shelf stability of an image part, chemical resistance, thermal head matching properties and resistance to an ink jet ink. SOLUTION: This heat-sensitive recording material has a heat-sensitive color developing layer containing an electron-donative colorless dye and an electron- receptive compound formed on a support. The heat-sensitive color developing layer contains a 4-hydroxybenzene sulfonanilide as the electron-receptive compound and contains at least one kind selected from the group consisting of a calcite soft calcium carbonate, amorphous silica and aluminum hydroxide, as an inorganic pigment.

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 in particular, it has high sensitivity, background fog, image storability, and chemical resistance. Thermal head matching characteristics (adhesion of debris to the thermal head, abrasion resistance of the thermal head). ), And a thermal recording material excellent in ink jet ink resistance.

[0002]

2. Description of the Related Art Generally, a heat-sensitive recording material is relatively inexpensive, and its recording equipment is compact and maintenance-free, and thus is widely used. Under such circumstances, recently, the sales competition of thermal paper has intensified, and it has been required to further enhance the functionality of the thermal recording material that is differentiated from the conventional functions, and research on the color density and image storability of the thermal recording material. Is earnestly done.

Conventionally, 2,2-bis (4-hydroxyphenyl) propane (so-called "bisphenol A") has been widely used as an electron-accepting compound for an electron-donating colorless dye used in such a heat-sensitive recording material. However, satisfactory results have not been obtained in terms of sensitivity, background fog, and image storability.

[0004]

The object of the present invention is to have high sensitivity, little background fog, and storability in the image area.
It is an object of the present invention to provide a thermal recording material having excellent chemical resistance, thermal head matching characteristics (such as adhesion of dust to the thermal head, abrasion resistance of the thermal head), and ink jet ink resistance.

[0005]

DISCLOSURE OF THE INVENTION The inventors of the present invention have made extensive studies on each of the electron-accepting compound, the sensitizer and the like, pursued the development of a good recording material, and completed the present invention. That is, the present invention is

<1> A heat-sensitive recording material having a thermosensitive coloring layer containing an electron-donating colorless dye and an electron-accepting compound on a support, wherein the thermosensitive coloring layer is the electron-accepting compound. A heat-sensitive recording material containing 4-hydroxybenzenesulfonanilide and at least one of calcite-based calcium carbonate, amorphous silica, and aluminum hydroxide as an inorganic pigment. <2> The content of the inorganic pigment is 50 to 250 parts by mass with respect to 100 parts by mass of the electron accepting compound <1.
The heat-sensitive recording material described in <>. <3> The volume average particle diameter of the inorganic pigment is 0.6 to 3.
The heat-sensitive recording material according to <1> or <2>, which has a thickness of 0 μm. <4> The support has an undercoat layer containing calcined kaolin having an oil absorption of 70 to 80 ml / 100 g as defined by JIS-K5101, and the undercoat layer is provided by blade coating <1> to The thermosensitive recording material according to any one of <3>.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION << Thermosensitive recording material >> The thermosensitive recording material of the present invention is a thermosensitive recording material having a thermosensitive coloring layer containing an electron-donating colorless dye and an electron-accepting compound on a support. The thermosensitive coloring layer contains 4-hydroxybenzenesulfonanilide as the electron-accepting compound, and further contains at least one of calcite-based calcium carbonate, amorphous silica, and aluminum hydroxide as an inorganic pigment. It is characterized by doing. The thermal recording material of the present invention will be described below.

<Support> As the support used in the present invention, a conventionally known support can be used. Specific examples thereof include a paper support such as high-quality paper, a coated paper obtained by coating a paper with a resin or a pigment, a resin-laminated paper, an undercoat base paper having an undercoat layer, a synthetic paper, or a support such as a plastic film. From the viewpoint of thermal head matching characteristics, an undercoat base paper having an undercoat layer is preferable, and an undercoat base paper provided with an undercoat layer containing an oil absorbing pigment using a blade coater is particularly preferable.

As the above support, JIS-P8119 is used.
From the viewpoint of dot reproducibility, a smooth support having a smoothness of 300 seconds or more defined by is preferable.

As described above, the support used in the present invention preferably has an undercoat layer. The undercoat layer is preferably provided on a support having a Steckigt size of 5 seconds or more, and preferably contains a pigment and a binder as main components. As the above-mentioned pigment, all the general inorganic and organic pigments can be used, but especially JIS-
Oil absorption specified by K5101 is 40 ml / 100 g (c
c / 100 g) or more oil-absorptive pigments are preferred. Examples of the oil absorbing pigment include calcined kaolin, aluminum oxide,
Examples thereof include magnesium carbonate, calcium carbonate, amorphous silica, calcined diatomaceous earth, aluminum silicate, magnesium aluminosilicate, and aluminum hydroxide. Among them, the oil absorption specified by JIS-K5101 is 70-80.
Especially preferred is ml / 100 g of calcined kaolin.

Examples of the binder used in the undercoat layer include water-soluble polymers and soluble binders. These may be used alone or in combination of two or more. As the water-soluble polymer,
Starch, polyvinyl alcohol, polyacrylamide, carboxymethyl alcohol, methyl cellulose,
Casein etc. are mentioned. As the soluble binder, synthetic rubber latex or synthetic resin emulsion is generally used, and styrene-butadiene rubber latex (SBR), acrylonitrile-butadiene rubber latex, methyl acrylate-butadiene rubber latex,
Examples thereof include vinyl acetate emulsion.

The amount of these binders used is determined in consideration of the film strength of the coating layer and the thermal sensitivity of the thermosensitive color developing layer, but it is 3 to 3 with respect to the pigment added to the undercoat layer.
It is 100% by mass, preferably 5 to 50% by mass, particularly preferably 8 to 15% by mass. Further, wax, a decoloring inhibitor, a surfactant and the like may be added to the undercoat layer.

A known coating method can be used for coating the undercoat layer. Specifically, a method using an air knife coater, a roll coater, a blade coater, a gravure coater, a curtain coater or the like can be used, and among them, blade coating using a blade coater is preferable. Further, if necessary, a smoothing process such as a calendar may be applied before use. The method using the blade coater is not limited to a coating method using a bevel type or bent type blade, and includes a rod blade coating method and a bill blade coating method, etc., and is not limited to an off-machine coater, and can be applied to a paper machine. You may coat with the installed on-machine coater. The degree of etherification of the coating liquid for the undercoat layer is 0.6 to 0.8 in order to impart fluidity during blade coating to obtain excellent smoothness and surface state.
Carboxymethyl cellulose having a weight average molecular weight of 20,000 to 200,000 is 1 to 5 mass% with respect to the above pigment,
Preferably, 1 to 3% by mass may be added.

The coating amount of the undercoat layer is not particularly limited, but is 2 g / m ² or more, preferably 4 g / m ² or more, and 7 g / m ^{2 to} 12 depending on the characteristics of the heat-sensitive recording material.
g / m ² is particularly preferred.

<Thermosensitive Coloring Layer> The thermosensitive coloring layer formed on the support contains at least an electron-donating colorless dye, an electron-accepting compound, and an inorganic pigment, and further contains a sensitizer and an image. A stabilizer may be contained.

(Electron-donating colorless dye) The above-mentioned electron-donating colorless dyes include 2-anilino-3-methyl-6-diethylaminofluorane and 2-anilino-3-methyl-6- (N
-Ethyl-N-isoamylamino) fluorane and 2
It is preferably at least one selected from -anilino-3-methyl-6- (N-ethyl-N-propylamino) fluorane and the like. These may be used alone or in combination of two or more. 2-anilino
3-Methyl-6-diethylaminofluorane, 2-anilino-3-methyl-6- (N-ethyl-N-isoamylamino) fluorane and 2-anilino-3-methyl-
By using at least one selected from 6- (N-ethyl-N-propylamino) fluorane and the like as the electron-donating colorless dye, the storage stability and chemical resistance of the image area can be improved.

The electron-donating colorless dye according to the present invention may be, for example, 3-di (n-butylamino) -6-methyl-7-anilinofluorane or 2-anilino-3 in addition to the above-mentioned ones. -Methyl-6-N-ethyl-N-sec-butylaminofluorane, 3-di (n-pentylamino)
-6-methyl-7-anilinofluorane, 3- (N-n
-Hexyl-N-ethylamino) -6-methyl-7-anilinofluorane, 3- [N- (3-ethoxypropyl) -N-ethylamino) -6-methyl-7-anilinofluorane, 3 -Di (n-butylamino) -7- (2-
Chloroanilino) fluorane, 3-diethylamino-7
-(2-Chloroanilino) fluorane, 3- (N-cyclohexyl-N-methylamino) -6-methyl-7-anilinofluorane and the like may be used. Further, these may be used alone or in combination of two or more kinds.

[0018] Examples of the coating amount of the electron-donating colorless dye, 0.1 to 1.0 g / m ² are preferred, color density and 0.2~0.5g terms of background fog density / m ² Gayori preferable.

(Electron-Accepting Compound) The heat-sensitive recording material of the present invention is characterized by containing 4-hydroxybenzenesulfonanilide as an electron-accepting compound. The heat-sensitive recording material of the present invention contains the above-mentioned 4-hydroxybenzenesulfonanilide as an electron-accepting compound,
It is possible to increase the density of color development, reduce background fog, and improve the storability of the image area. The amount of the electron-accepting compound added is 50 with respect to the electron-donating colorless dye.
To 400% by mass, preferably 100 to 300
Mass% is particularly preferred.

The electron-accepting compound of the present invention includes 4-
In addition to hydroxybenzenesulfonanilide, other known electron-accepting compounds may be used in combination as long as the effects of the present invention are not impaired.

The above-mentioned known electron-accepting compound can be appropriately selected and used, but a phenolic compound or a salicylic acid derivative and a polyvalent metal salt thereof are particularly preferable from the viewpoint of suppressing background fog. Examples of the phenolic compound include 2,2'-bis (4-hydroxyphenol) propane (bisphenol A), 4-t-butylphenol, 4-phenylphenol, 4-hydroxydiphenoxide, 1,1'-bis. (4-hydroxyphenyl) cyclohexane, 1,1′-bis (3-chloro-4-hydroxyphenyl) cyclohexane, 1,
1'-bis (3-chloro-4-hydroxyphenyl)-
2-ethylbutane, 4,4'-sec-isooctylidenediphenol, 4,4'-sec-butylylenediphenol, 4-tert-octylphenol, 4-p-
Methylphenylphenol, 4,4'-methylcyclohexylidenephenol, 4,4'-isopentylidenephenol, 4-hydroxy-4-isopropyloxydiphenylsulfone, 4,4'-dihydroxydiphenylsulfone, 2-4'- Dihydroxydiphenyl sulfone, 2,4-bis (phenylsulfonyl) phenol, N
Examples thereof include-(4-hydroxyphenyl) -p-toluenesulfonamide and benzyl p-hydroxybenzoate.

As the salicylic acid derivative, 4
-Pentadecylsalicylic acid, 3-5-di (α-methylbenzyl) salicylic acid, 3,5-di (tert-octyl) salicylic acid, 5-octadecylsalicylic acid, 5-α
-(P-α-methylbenzylphenyl) ethylsalicylic acid, 3-α-methylbenzyl-5-tert-octylsalicylic acid, 5-tetradecylsalicylic acid, 4-hexyloxysalicylic acid, 4-cyclohexyloxysalicylic acid, 4-decyloxysalicylic acid, 4-dodecyloxysalicylic acid, 4-pentadecyloxysalicylic acid, 4
-Octadecyloxysalicylic acid and the like and zinc thereof,
Aluminum, calcium, copper, lead salts and the like are also included.

When the above-mentioned known electron-accepting compound is used in combination in the present invention, the content of 4-hydroxybenzenesulfonanilide according to the present invention is 50% by mass or more, particularly 70 It is preferably at least mass%.

In the present invention, when the coating liquid for the heat-sensitive color forming layer is prepared, the particle size of the electron-accepting compound is preferably 1.0 μm or less in terms of volume average particle size, and is 0.5 to 0.5.
0.7 μm is more preferable. The volume average particle size is
If it exceeds 1.0 μm, the thermal sensitivity may decrease.
The volume average particle diameter can be easily measured by a laser diffraction type particle size distribution measuring device (for example, LA500 (manufactured by Horiba Ltd.) or the like.

(Inorganic Pigment) The thermosensitive coloring layer according to the present invention comprises
It is characterized in that it contains at least one or more of calcite-based calcium carbonate, amorphous silica, and aluminum hydroxide as the inorganic pigment.

The content of the above-mentioned inorganic pigment is preferably 50 to 250 parts by mass, and 70 to 170 parts by mass with respect to 100 parts by mass of the electron-accepting compound, from the viewpoint of color density and adhesion of dust to the thermal head. More preferably, 9
Particularly preferred is 0 to 140 parts by mass. Further, the particle size of the inorganic pigment is preferably 0.6 to 2.5 μm, more preferably 0.8 to 2.0 μm in terms of color density and dust adhesion to the thermal head. 1.0 to 1.6 μm is particularly preferable.

Light calcium carbonate generally has a crystal form of calcite, aragonite, vaterite, etc., but as the inorganic pigment according to the present invention, calcite-based light calcium carbonate is used in terms of absorbability, hardness and the like. Further, it is preferable that the particles have a spindle shape or an oblate triangular surface state.
As a method for producing the calcite-based light calcium carbonate, a known production method can be used.

Further, within a range not impairing the effects of the present invention,
Other inorganic pigments may be used in combination with the above inorganic pigments. Examples of the other inorganic pigments include calcium carbonate other than calcite-based light calcium carbonate, barium sulfate, lithopone, wax, kaolin, calcined kaolin, and amorphous silica. When the inorganic pigment according to the present invention is used in combination with the other inorganic pigment, the ratio (v / w) of the total mass (v) of the inorganic pigment according to the present invention and the total mass (w) of the other inorganic pigment. )But,
It is preferably 100/0 to 60/40, and 100
More preferably, it is / 0 to 80/20.

(Sensitizer) The heat-sensitive recording material of the present invention comprises 2-benzyloxynaphthalene, dimethylbenzyl oxalate, m-terphenyl, as a sensitizer in the heat-sensitive color forming layer.
It is preferable to include ethylene glycol tolyl ether and p-benzyl biphenyl. By containing these sensitizers, the sensitivity can be further improved.

The content of the above-mentioned sensitizer is 4-hydroxybenzenesulfonanilide 100 which is an electron-accepting compound.
The amount is preferably 75 to 200 parts by mass, more preferably 100 to 150 parts by mass with respect to parts by mass. When the content of the sensitizer is within the range of 75 to 200 parts by mass,
The effect of improving the sensitivity is great and the image storability is also good.

The thermosensitive coloring layer according to the present invention includes the above-mentioned 2-benzyloxynaphthalene, dimethylbenzyl oxalate, m
-Terphenyl, ethylene glycol tolyl ether,
In addition to p-benzylbiphenyl, other sensitizers may be used in combination as long as the effects of the present invention are not impaired. Examples of the other sensitizer include aliphatic monoamide, stearyl urea, p-benzyl biphenyl, di (2-methylphenoxy) ethane, di (2-methoxyphenoxy) ethane, β-naphthol- (p-methylbenzyl) ether. , Α-naphthylbenzyl ether, 1,4-butanediol-p-methylphenyl ether, 1,4-butanediol-p-isopropylphenyl ether, 1,4
-Butanediol-p-tert-octylphenyl ether, 1-phenoxy-2- (4-ethylphenoxy) ethane, 1-phenoxy-2- (chlorophenoxy) ethane, 1,4-butanediol phenyl ether, diethylene glycol bis ( 4-methoxyphenyl) ether, m-terphenyl, oxalic acid methylbenzyl ether, 1,2-diphenoxymethylbenzene,
1,2-bis (3-methylphenoxy) ethane, 1,4
-Bis (phenoxymethyl) benzene and the like.

<Image Stabilizer> Further, the heat-sensitive color forming layer can further improve the storability of the image area by containing an image stabilizer. The image stabilizer is preferably used in an amount of 10 to 100 parts by mass, based on 100 parts by mass of the electron-donating colorless dye, from the viewpoint of efficiently exhibiting the desired effect of background fog and image storability. ~ 6
It is more preferably 0 part by mass.

As the image stabilizer, a phenol compound,
Hindered phenol compounds are particularly effective, for example, 1,1,3-tris (2-ethyl-4-hydroxy-5).
-Cyclohexylphenyl) butane, 1,1,3-tris (3,5-di-tert-butyl-4-hydroxyphenyl) butane, 1,1,3-tris (2-methyl-4)
-Hydroxy-5-tert-butylphenyl) propane, 2,2'-methylene-bis (6-tert-butyl-4-methylphenol), 2,2'-methylene-bis (6-tert-butyl-4-) Ethylphenol) 4,
4'-butylidene-bis (6-tert-butyl-3-
Methylphenol), 4,4′-thio-bis- (3-methyl-6-tert-butylphenol) and the like.

In the present invention, an electron-donating colorless dye,
The electron-accepting compound and the sensitizer can be dispersed in a water-soluble binder. The water-soluble binder used in this case is preferably a compound that dissolves in 5% by mass or more of water at 25 ° C.

Specific examples of the water-soluble binder include:
Polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, starches (including modified starch), gelatin, gum arabic, casein, styrene-
Examples thereof include saponified maleic anhydride copolymers.

These binders are not only used at the time of dispersion,
It is also used for the purpose of improving the coating strength of the thermosensitive coloring layer, but for this purpose, a styrene-butadiene copolymer, a vinyl acetate copolymer, an acrylonitrile-butadiene copolymer, a methyl acrylate-butadiene copolymer is used. Polymer,
A binder of a synthetic polymer latex such as polyvinylidene chloride may be used together.

The above-mentioned electron-donating colorless dye, electron-accepting compound, sensitizer and the like are simultaneously or separately dispersed by a stirrer / pulverizer such as a ball mill, attritor or sand mill to prepare a coating liquid. In the coating liquid, if necessary, metal soap, wax, surfactant, antistatic agent,
An ultraviolet absorber, an antifoaming agent and a fluorescent dye may be added.

As the metal soap, higher fatty acid metal salts are used, such as zinc stearate, calcium stearate and aluminum stearate. As the wax, paraffin wax, microcrystalline wax, carnauba wax, methylol stearamide, polyethylene wax, polystyrene wax, fatty acid amide wax and the like are used alone or in combination. As the surfactant, a sulfosuccinic acid-based alkali metal salt, a fluorine-containing surfactant or the like is used.

It is effective to use a cationic polymer in the heat-sensitive recording material of the present invention in order to impart suitability for ink jet recording. The cationic polymer may be added to either the heat-sensitive recording layer or the protective layer. Examples of the cationic polymer include polyethyleneimine, polydiallylamine, polyallylamine, polydiallyldimethylammonium chloride, polymethacryloyloxyethyl-β-hydroxyethyldimethylammonium chloride, polyallylamine hydrochloride, polyamide-polyamine resin, cationized starch. , Dicyandiamide formalin condensate, dimethyl-2-hydroxypropylammonium salt polymer, polyamidine, polyvinylamine and the like.

These materials are mixed and then applied to the support. The coating method is not particularly limited, and for example, it is applied using an air knife coater, roll coater, blade coater, curtain coater or the like, dried, and then smoothed with a calender to be used. In particular, a method using a curtain coater is preferable for the present invention. Further, the coating amount of the heat-sensitive color forming layer is not limited, and usually a dry mass of about ² to 7 g / m ² is preferable.

Further, the heat-sensitive recording material of the present invention preferably has an image storage ratio of 65% or more. The image retention rate is measured immediately after printing by a Macbeth reflection densitometer (for example, RD
It is represented by the ratio of the image density after printing under the same conditions for 24 hours in an atmosphere of 60 ° C. and 20% relative humidity to the image density measured in −918). Image preservation rate = [(image density after leaving under the above conditions) / (image density immediately after printing)] x 100

A protective layer may be provided on the thermosensitive coloring layer, if desired. The protective layer may contain organic or inorganic fine powder, a binder, a surfactant, a heat fusible substance and the like. Examples of the fine powder include calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, inorganic fine powder such as surface-treated calcium and silica, and urea. -Formalin resin, styrene / methacrylic acid copolymer, organic fine powder such as polystyrene and the like can be used.

As the binder in the protective layer, polyvinyl alcohol, carboxy-modified polyvinyl alcohol, vinyl acetate-acrylamide copolymer, silicon-modified polyvinyl alcohol, starch, modified starch, methyl cellulose, carboxymethyl cellulose, hydroxymethyl cellulose, gelatins, arabic gum, casein. , Styrene-maleic acid copolymer hydrolyzate, polyacrylamide derivative, polyvinylpyrrolidone, and styrene-
Latexes such as butadiene rubber latex, acrylonitrile-butadiene rubber latex, methyl acrylate-butadiene rubber latex, and vinyl acetate emulsion can be used.

It is also possible to add a waterproofing agent for further improving the storage stability of the heat-sensitive recording material by crosslinking the binder component in the protective layer. Water-resistant agents include water-soluble initial condensates such as N-methylol urea, N-methylol melamine and urea-formalin, dialdehyde compounds such as glyoxal and glutaraldehyde, and inorganic crosslinking agents such as boric acid, borax and colloidal silica. , Polyamide epichlorohydrin and the like.

[0045]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples. Unless otherwise specified, "parts" and "%" in the examples mean "parts by mass" and "% by mass", respectively. Furthermore, unless otherwise specified, in the examples, "average particle size" is
"Volume average particle diameter" is shown.

[Example 1] << Formation of thermosensitive recording material >><Preparation of coating liquid for thermosensitive coloring layer> (Preparation of dispersion liquid A) The following components were mixed while being dispersed by a sand mill to give an average particle diameter of 0. A dispersion A of 0.6 μm was obtained. [Composition of dispersion A] 2-anilino-3-methyl-6-diethylaminofluorane 10 parts (electron-donating colorless dye) 50% polyvinyl alcohol solution 50 parts (PVA-105, manufactured by Kuraray Co., Ltd.)

(Preparation of Dispersion Liquid B) The following components were mixed while being dispersed by a sand mill to obtain a dispersion liquid B having an average particle diameter of 0.6 μm. [Composition of Dispersion B] -Hydroxybenzenesulfonanilide 25 parts (electron-accepting compound) -Polyvinyl alcohol 2.5% solution 100 parts (PVA-105, manufactured by Kuraray Co., Ltd.)

(Preparation of Dispersion C) The following components were dispersed in a sand mill and mixed to obtain Dispersion C having an average particle size of 0.6 μm. [Dispersion C composition] 25 parts of 2-benzyloxynaphthalene (sensitizer) 100 parts of polyvinyl alcohol 2.5% solution (PVA-105, manufactured by Kuraray Co., Ltd.)

(Preparation of Pigment Dispersion Liquid D) The following components were dispersed in a sand mill and mixed to give an average particle diameter of 1.2 μm.
A pigment dispersion D of m was obtained. [Pigment dispersion D composition] 30 parts calcite-based light calcium carbonate (Uniber 70, manufactured by Shiroishi Industry Co., Ltd.) 0.3 parts sodium hexametaphosphate 40 parts distilled water

A compound having the following composition was mixed to obtain a coating solution for a thermosensitive color developing layer. [Coating liquid composition for thermosensitive coloring layer] -Dispersion A 60 parts-Dispersion B 125 parts-Dispersion C 125 parts-Pigment dispersion D 70 parts-Zinc stearate 30% dispersion 15 parts-Paraffin wax (30% ) 15 parts ・ Sodium dodecylbenzene sulfonate (25%) 4 parts

(Preparation of coating liquid for support undercoat layer) The following components were stirred and mixed with a dissolver to prepare SBR.
20 parts of (styrene-butadiene latex) and 25 parts of oxidized starch (25%) were added to obtain a coating solution for a support undercoat layer. [Coating liquid composition for support undercoat layer] 100 parts of calcined kaolin (oil absorption 75 ml / 100 g) 100 parts of sodium hexametaphosphate 110 parts of distilled water

<Formation of heat-sensitive recording material> A substrate undercoat layer was formed on a high quality base paper weighing 50 g / m ² with a Steckigt sizing degree of 10 seconds so that the coating amount after drying was 8 g / m ² by a blade coater. The coating liquid was applied, and after the layer was dried, a calendering treatment was performed to produce an undercoat paper. Next, the coating solution for heat-sensitive recording material was applied onto the undercoat layer by a curtain coater so that the coating amount after drying was 4 g / m ^2, and then dried. The surface of the formed thermosensitive coloring layer was subjected to a calendering treatment to obtain a thermosensitive recording material according to Example 1.

Example 2 A calcite-based light calcium carbonate (Uniber) of the pigment dispersion D in Example 1 was used.
Example 1 except that 70) was changed to calcite-based light calcium carbonate (Tamapearl 121, manufactured by Okutama Kogyo).
A heat-sensitive recording material according to Example 2 was obtained in the same manner as in.

[Example 3] The calcite-based light calcium carbonate (Uniber) of the pigment dispersion D in Example 1 was used.
70) to aluminum hydroxide (Hidilite H42,
A heat-sensitive recording material according to Example 3 was obtained in the same manner as in Example 1 except that it was changed to Showa Denko.

Example 4 Example 1 is the same as Example 1, except that the amount of the pigment dispersion D is changed from 70 parts to 35 parts.
A heat-sensitive recording material according to Example 4 was obtained in the same manner as in.

Example 5 A heat-sensitive recording material according to Example 5 was obtained in the same manner as in Example 1 except that the amount of the pigment dispersion D in Example 1 was changed from 70 parts to 140 parts.

Example 6 A thermosensitive recording material according to Example 6 was obtained in the same manner as in Example 1 except that the amount of the pigment dispersion D in Example 1 was changed from 70 parts to 17.5 parts. .

Example 7 A heat-sensitive recording material according to Example 7 was obtained in the same manner as in Example 1 except that the amount of the pigment dispersion D in Example 1 was changed from 70 parts to 210 parts.

Example 8 Dispersion D in Example 1
A heat-sensitive recording material according to Example 8 was obtained in the same manner as in Example 1 except that the average particle size of was changed from 1.2 μm to 2.2 μm.

Example 9 Dispersion D in Example 1
A heat-sensitive recording material according to Example 9 was obtained in the same manner as in Example 1 except that the average particle size of was changed from 1.2 μm to 0.8 μm.

[Example 10] A thermosensitive recording material according to Example 10 in the same manner as in Example 1 except that the average particle diameter of the dispersion D in Example 1 was changed from 1.2 µm to 0.5 µm. Got

[Example 11] A heat-sensitive recording material according to Example 11 was prepared in the same manner as in Example 1 except that the average particle diameter of the dispersion D was changed from 1.2 µm to 3.0 µm. Got

[Example 12] In Example 1, instead of the blade coater, an air knife coater was used, and a coating amount after drying was 8 g / m ² on a fine base paper weighing 50 g / m ² with a Steckigt sizing degree of 10 seconds. In order to obtain the following undercoat layer coating solution, the thermosensitive recording material according to Example 12 was prepared in the same manner as in Example 1 except that an undercoat base paper was prepared by drying and calendering. Got (Preparation of coating liquid for support undercoat layer) 20 parts of SBR (styrene-butadiene latex) and oxidized starch (25%) were mixed by stirring the following components with a dissolver.
And 25 parts were added to obtain a coating solution for a support undercoat layer. [Coating liquid composition for support undercoat layer] 100 parts of calcined kaolin (oil absorption 75 ml / 100 g) 100 parts of sodium hexametaphosphate 1 part of distilled water 314 parts

Example 13 Example 13 was repeated in the same manner as in Example 1 except that the coating liquid for heat-sensitive recording material was applied on the undercoat layer by using an air knife coater instead of the curtain coater. The heat-sensitive recording material was obtained.

[Example 14] The calcite-based light calcium carbonate (Unibe) of the pigment dispersion D in Example 1 was used.
Example 1 was repeated in the same manner as in Example 1 except that r70) was changed to kaolin (kao gloss, manufactured by Shiraishi Calcium).
A heat-sensitive recording material according to No. 4 was obtained.

[Example 15] In Example 1, before carrying out the calendering treatment on the formed thermosensitive coloring layer, the following protective layer coating solution was further applied onto the thermosensitive coloring layer at a dry coating amount of 2 g / Apply with a curtain coater to obtain m ² .
A thermosensitive recording material according to Example 15 was obtained in the same manner as in Example 1 except that the protective layer was formed by drying and the surface of the protective layer was subjected to calendering.

<Preparation of Coating Liquid for Protective Layer> First, a compound having the following composition was dispersed by a sand mill to prepare a pigment dispersion having an average particle diameter of 2 μm. Subsequently, 200 parts of urea phosphate esterified starch 15% aqueous solution (MS4600, manufactured by Nippon Shokuhin Kako Co., Ltd.) and polyvinyl alcohol 15%
Water (60 parts) was added to 200 parts of an aqueous solution (PVA-105, manufactured by Kuraray Co., Ltd.), and the pigment dispersion was further mixed. Further, an average particle diameter of 0.15 μm zinc stearate emulsion dispersion (Hydrin F115, Chukyo Yushi ( (Manufactured by Co., Ltd.) and 125 parts of a 2% aqueous solution of sulfosuccinic acid 2-ethylhexyl ester sodium salt were mixed to obtain a coating liquid for protective layer. [Composition of coating liquid for protective layer] -Aluminum hydroxide (average particle size 1 µm) 40 parts (Hidilite H42, Showa Denko KK) -Sodium polyacrylate 1 part-Water 60 parts

[Example 16] The calcite-based light calcium carbonate (Uniber) of the pigment dispersion D in Example 1 was used.
A heat-sensitive recording material according to Example 16 was obtained in the same manner as in Example 1 except that 70) was changed to amorphous silica (Mizukasil P78A, manufactured by Mizusawa Chemical Co., Ltd.).

Example 17 In Example 16, polyamine polyamide epichlorohydrin (Arafic 2300,
Example 1 except that 30 parts of Arakawa Chemical Co., Ltd.) was added.
A heat-sensitive recording material according to Example 17 was obtained in the same manner as in 6.

Comparative Example 1 The calcite-based light calcium carbonate (Uniber) of the pigment dispersion D in Example 1 was used.
A heat-sensitive recording material according to Comparative Example 1 was obtained in the same manner as in Example 1 except that 70) was changed to aragonite-based calcium carbonate (Callite SA, manufactured by Shiraishi Kogyo).

Comparative Example 2 Dispersion B in Example 1
4-hydroxybenzenesulfonanilide of 2,2-
A heat-sensitive recording material according to Comparative Example 2 was obtained in the same manner as in Example 1 except that bis (4-hydroxyphenyl) propane [bisphenol A] was used.

[Comparative Example 3] 4-hydroxybenzenesulfonanilide of Dispersion B in Example 1 was replaced with N-benzyl-4-hydroxybenzenesulfonamide (= p-N).
-Benzylsulfamoylphenol) was obtained in the same manner as in Example 1 to obtain a heat-sensitive recording material according to Comparative Example 3.

<< Evaluation >> (1) Sensitivity Kyocera Corp. thermal head (KJT-216-8M)
PD1) and a thermal printing device having a pressure roll of 100 kg / cm ² immediately before the head, and
No. 7 and Comparative Examples 1 to 3 were used to print. The print has a head voltage of 24 V and a pulse cycle of 10 m.
Printing was performed with a pulse width of 1.5 ms under the condition of s, and the printing density was measured with a Macbeth reflection densitometer (RD-918). The results are shown in Table 1.

(2) Background fogging For the heat-sensitive recording materials obtained in Examples 1 to 17 and Comparative Examples 1 to 3, the background was left for 24 hours in an environment of 60 ° C. and relative humidity of 20%. Reflection densitometer (R
D-918). The results are shown in Table 1. The lower the value, the better the result.

(3) Image storability Images were recorded on the thermosensitive recording materials obtained in Examples 1 to 17 and Comparative Examples 1 to 3 under the same apparatus and conditions as in (1) above, and the relative temperature was kept at 60 ° C. It was left for 24 hours in an environment of 20% humidity. After that, the image density was measured by Macbeth reflection densitometer (R
D-918), and the residual ratio with respect to the image density of the unprocessed product on which an image was recorded under the same apparatus and conditions as in (1) above was calculated from the following formula. The results are shown in Table 1. In addition,
The higher the value, the better the image storability. Image storability (%) = (image density after leaving / image density of unprocessed product) × 100

(4) Chemical resistance On the surface of the heat-sensitive recording materials obtained in Examples 1 to 17 and Comparative Examples 1 to 3, a highlighter pen (Zebra highlighter 2-pink,
Writing was carried out with Zebra Co., Ltd., and the occurrence of background fog and the stability of the image area of each heat-sensitive recording material after 1 day were visually observed and evaluated according to the following criteria. The results are shown in Table 1. [Criteria] ◯: No fogging was observed, and no change was observed in the image area. B: Occurrence of some fog was recognized, and decolorization of the image area was slightly recognized. X: Fogging was remarkably observed. In addition, the image area was erased.

(5) Dust adhesion FAX (SFX85, manufactured by Sanyo Electric Co., Ltd.) of the thermal head, and No. 3 charts, the thermal recording materials obtained in Examples 1 to 17 and Comparative Examples 1 to 3 were each printed for about 100 m. Then, the degree of residue adhered to the thermal head was observed and evaluated according to the following criteria. The results are shown in Table 1. [Standard] ⊚: No adhesion of dust was observed, and no white spots were observed in the print. ◯: The amount of adhered dust was very small, and white spots and the like were not found in the prints. B: The amount of adhered dust was moderate, but white spots and the like were not observed on the print. X: A large amount of dust adhered, and defects such as white spots were observed in the print.

(6) Wearability of thermal head For the thermal recording materials obtained in Examples 1 to 17 and Comparative Examples 1 to 3, Word Processor (Lupo JV, Lupo JV,
1000 sheets of A4 sheet size were printed using a test chart with a printing rate of 20% (manufactured by Toshiba Corporation).
After that, observe the wear level of the serial thermal head,
It evaluated according to the following criteria. The results are shown in Table 1. [Criteria] A: No wear of the thermal head was observed, and no white spots were observed in the prints. ◯: The thermal head was hardly worn, and no white spots were found in the prints. Δ: The thermal head was slightly worn, but white spots and the like were not found in the print. X: The degree of wear of the thermal head was large, and defects such as white spots were found in the prints.

(7) Inkjet recording suitability "Lupo JW-95" word processor manufactured by Toshiba Corp.
Inkjet printing on a sheet with characters printed on "JU"
Print with a printer, blur the ink jet recording and erase the characters recorded with the word processor,
The visual evaluation was made according to the following criteria. ◎ ……… No bleeding or erasing was observed, and there was no problem in reading. ○ ……… It became slightly thin, but there was no problem in reading. △ ……… Although the letters were faint, they were readable. × ……… The characters were completely lost and it was impossible to read them.

(8) Inkjet ink resistant inkjet printer (“M” manufactured by Epson Corporation)
(J930C)) and the heat-sensitive recording surface of the heat-sensitive recording material printed in the same manner as in the case of (1) Sensitivity were contacted, and the image density after standing at 25 ° C for 48 hours was measured with Macbeth RD918. did. Also,
The image density of the untreated product was also measured, and the ratio of the image density of the treated product to this (residual rate) was calculated. The higher the value, the better the ink jet ink resistance.

[0081]

[Table 1]

From Table 1, the heat-sensitive recording materials according to Examples 1 to 17 were good in sensitivity, background fog, image storability, chemical resistance, head residue adhesion, and head wear. In particular, it has been found that the above-mentioned performance is further excellent in the heat-sensitive recording material in which the amount of the inorganic pigment used is 50 to 250% of the electron-accepting compound. In addition, comparison between Example 1 and Example 12 revealed that the image stability was excellent when the undercoat layer was applied using a blade coater. On the other hand, the thermal recording materials according to Comparative Examples 1 to 3 were inferior in any of the above performances. In particular,
When bisphenol A is used as the electron-accepting compound,
Image storability was extremely low.

[0083]

As described above, according to the present invention, the thermosensitive coloring layer contains 4-hydroxybenzenesulfonanilide as an electron accepting compound, and further, as an inorganic pigment, a calcite-based light calcium carbonate, Crystalline silica,
By containing at least one of aluminum hydroxide and aluminum hydroxide, as compared with the conventional thermal recording material, the sensitivity, the background fog, the storage stability of the image area, and the chemical resistance are excellent, and the thermal head matching property ( It is possible to provide a heat-sensitive recording material having excellent adhesion of dust to the thermal head and abrasion resistance of the thermal head.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hirofumi Mitsuo             200, Onakazato, Fujinomiya City, Shizuoka Prefecture Fuji Photo             Within Film Co., Ltd. F term (reference) 2H026 AA07 BB01 BB25 DD32 DD53                       DD57 FF15 HH05

Claims (4)

[Claims] 1. A heat-sensitive recording material having a thermosensitive coloring layer containing an electron-donating colorless dye and an electron-accepting compound on a support, wherein the thermosensitive coloring layer contains 4 as the electron-accepting compound. A heat-sensitive recording material containing hydroxybenzenesulfonanilide and at least one of calcite-based calcium carbonate, amorphous silica, and aluminum hydroxide as an inorganic pigment. 2. The heat-sensitive recording material according to claim 1, wherein the content of the inorganic pigment is 50 to 250 parts by mass with respect to 100 parts by mass of the electron-accepting compound. 3. The volume average particle diameter of the inorganic pigment is 0.6.
The heat-sensitive recording material according to claim 1 or 2, wherein the heat-sensitive recording material has a thickness of ˜3.0 μm. 4. The support has an undercoat layer containing calcined kaolin having an oil absorption of 70 to 80 ml / 100 g as defined by JIS-K5101, and the undercoat layer is provided by blade coating. The thermal recording material according to any one of claims 1 to 3.