JP2003011524A - Heat-sensitive recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-sensitive recording material which shows high color development density and sensitivity and also superiority in terms of image shelf stability, suitability for printing, suitability for ink jet printing and ink jet ink resistance and further, is almost free from a texture fog. 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 at least one kind of modified polyvinyl alcohol selected from the group of a sulfo modified polyvinyl alcohol, a diacetone modified polyvinyl alcohol and an acetoacetyl modified polyvinyl alcohol as an adhesive.

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 high color density and sensitivity and excellent background fog, image storability, printability, ink jet printability and ink jet ink resistance. Regarding

[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.

On the other hand, Japanese Patent Publication No. 4-20792 discloses that
A recording material using N-substituted sulfamoylphenol or N-substituted sulfamoylnaphthol as an electron-accepting compound is described. This recording material (pressure-sensitive, heat-sensitive) has improved image density, image stability, cost and the like. However, there is room for further improvement in image density and image storability.

In general, thermal recording materials have a weak surface strength and are inferior in printability due to problems such as paper peeling during offset printing. In order to avoid such troubles, it is conceivable to increase the content of the adhesive contained in the thermosensitive coloring layer. However, when the content of the adhesive is increased, there is a problem that the coloring density of the heat-sensitive recording material is lowered as a harmful effect. In order to solve these problems, there has been a strong demand for a heat-sensitive recording material having a high color density and excellent printability.

Further, when full-color information is recorded on a heat-sensitive recording material, ink-jet ink may be used for recording. However, when ink-jet recording is performed on a normal heat-sensitive recording material, ink color is reproduced faithfully. The color may not be vivid and may be dull.

In recent years, ink jet printers have become widespread as an output application from personal computers, and in offices and the like, recording surfaces of an ink jet recording material and a heat sensitive recording material are overlapped with each other. However, since the conventional thermal recording material has insufficient resistance to ink-jet ink, when the recording surface of the thermal recording material comes into contact with the recording surface of the inkjet recording material, fogging of the background portion of the thermal recording material or image area There was a problem of causing a decrease in density.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and its purpose is to have high color density and high sensitivity, and excellent background fog, image storability and printability. Furthermore, it is to provide a heat-sensitive recording material excellent in inkjet printability and inkjet ink resistance.

[0009]

The above-mentioned problems can be solved by providing the following heat-sensitive recording material.

<1> A thermosensitive 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 serves as the electron-accepting compound. A heat-sensitive material containing 4-hydroxybenzenesulfonanilide and further containing, as an adhesive, at least one modified polyvinyl alcohol selected from sulfo-modified polyvinyl alcohol, diacetone-modified polyvinyl alcohol and acetoacetyl-modified polyvinyl alcohol. Recording material.

<2> The content of the modified polyvinyl alcohol is 70 to 200% by mass based on 100 parts by mass of the electron-donating colorless dye <1>
The heat-sensitive recording material described in.

<3> The modified polyvinyl alcohol has a saponification degree of 85 to 99 mol% and a polymerization degree of 200 to
The heat-sensitive recording material as described in <1> or <2>, which is 2000.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION <Heat-sensitive recording material> The heat-sensitive recording material of the present invention is a heat-sensitive recording material having a heat-sensitive 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 at least one selected from sulfo-modified polyvinyl alcohol, diacetone-modified polyvinyl alcohol and acetoacetyl-modified polyvinyl alcohol as an adhesive. Characterized in that it contains a modified polyvinyl alcohol of the species. The thermosensitive recording material of the present invention will be described below in the order of the support and the thermosensitive coloring layer.

<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, a high-quality paper having an undercoat layer, a synthetic paper, or a plastic film.

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

Further, the support used in the present invention may have an undercoat layer. When an undercoat layer is provided on the support, it is preferable to provide an undercoat layer containing a pigment as a main component. As the pigment, all of general inorganic and organic pigments can be used, but those having an oil absorption of 40 ml / 100 g (cc / 100 g) or more specified by JIS-K5101 are particularly preferable. Specifically, calcium carbonate,
Examples thereof include barium sulfate, aluminum hydroxide, kaolin, calcined kaolin, amorphous silica, urea formalin resin powder and the like. Among them, the oil absorption is 70 ml / 100
Particularly preferred is g to 80 ml / 100 g of calcined kaolin. When these pigments are applied to the support, the amount of pigment is 2 g / m ² or more, preferably 4 g / m ² or more, and 7 g / m ^{2 to} 12 g / m ² is particularly preferable.

Examples of the binder used in the undercoat layer include water-soluble polymers and aqueous binders. These may be used alone or in combination of two or more. As the water-soluble polymer, starch,
Examples thereof include polyvinyl alcohol, polyacrylamide, carboxymethyl alcohol, methyl cellulose, casein and the like. As the aqueous binder, a synthetic rubber latex or a synthetic resin emulsion is generally used,
Examples thereof include styrene-butadiene rubber latex, acrylonitrile-butadiene rubber latex, methyl acrylate-butadiene rubber latex, vinyl acetate emulsion and the like. The amount of these binders used is 3 to 100% by mass, preferably 5 to 50% by mass, and particularly preferably 8 to 15% by mass, based on the pigment added to the undercoat layer. 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,
Of these, the method using a blade coater is preferable. Further, if necessary, a smoothing process such as a calendar may be applied before use.

<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 adhesive, and further contains a sensitizer and an image stabilizer. The agent 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-6-
By using at least one selected from (N-ethyl-N-propylamino) fluorane and the like as the electron-donating colorless dye, the color density, the storage stability of the image area, and the chemical resistance 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.

[0022] Examples of the coating amount of the electron-donating colorless dye, 0.1 to 1.0 g / m ² are preferred, coloring density and 0.2-0.5 g / m ² Gayori terms of background fog density 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,
A heat-sensitive recording material excellent in color density, image storability and background fog can be obtained. The amount of the electron-accepting compound added is preferably 50 to 400% by mass, and particularly preferably 100 to 300% by mass, based on the electron-donating colorless dye.

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, a salicylic acid derivative and a polyvalent metal salt thereof are particularly preferable from the viewpoint of suppressing background fogging. 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, benzyl p-hydroxybenzoate,
4,4'-dihydroxydiphenyl sulfone, 2,4 '
-Dihydroxydiphenyl sulfone and the like.

Further, 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, especially 70% of the total electron-accepting compound. It is preferably at least mass%.

In the present invention, when the coating liquid for the thermosensitive color developing layer is prepared, the particle diameter of the electron-accepting compound is preferably 1.0 μm or less in terms of volume average particle diameter, 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 also be easily measured by a laser diffraction type particle size distribution measuring device (for example, LA500 (manufactured by Horiba Ltd.) or the like.

(Adhesive) The thermosensitive coloring layer according to the present invention uses, as an adhesive, at least one modified polyvinyl alcohol selected from sulfo-modified polyvinyl alcohol, diacetone-modified polyvinyl alcohol and acetoacetyl-modified polyvinyl alcohol (hereinafter, appropriately, Specific modified PVA
Sometimes called. ) Is contained.
The present invention uses the above-mentioned specific modified PV as an adhesive for the thermosensitive coloring layer.
By including A, the interlayer adhesion between the thermosensitive color developing layer and the support is increased, and problems such as paper peeling that occur during offset printing and the like are prevented, so that printability can be improved. Further, the thermosensitive coloring layer according to the present invention comprises a specific modified PV.
By containing A, it is possible to improve the color density in recording with a thermal head.

The above specific modified PVA may be used alone or in combination, and other modified PVA or polyvinyl alcohol (PVA) may be used in combination. When the other modified PVA or PVA is used in combination, the above specific modified PVA
Is preferably contained in an amount of 10% by mass or more, and more preferably 20% by mass or more, based on the total mass of the adhesive component.

The specific modified PVA preferably has a saponification degree of 85 to 99 mol%. The specific modified P
When the degree of saponification of VA is less than 85 mol%, the water resistance to the fountain solution used for offset printing is insufficient, and so-called paper peeling easily occurs. On the other hand, the specific modification P
If the amount of VA added is increased to prevent the peeling of the paper, the color density decreases. In addition, the saponification degree is 99 mol%
If it exceeds the range, undissolved substances are liable to be generated during the preparation of the coating solution, which causes defective portions, which is not preferable. In addition, in order not to impair the effects of the present invention, other modified PVA
When used together with or PVA, the saponification degree of the other modified PVA or PVA is preferably within the above range.

Furthermore, it is preferable that the specific modified PVA has a degree of polymerization of 200 to 2000. If the degree of polymerization of the specific modified PVA is less than 200, paper peeling is likely to occur during offset printing, and if the addition amount is increased to improve the paper peeling, the color density will decrease. Further, when the degree of polymerization exceeds 2000, the specific modified PVA is difficult to dissolve in the solvent and the viscosity of the coating solution becomes high, so that preparation and coating of the coating solution become difficult. The degree of polymerization referred to in the present invention means the average degree of polymerization obtained by the method described in JIS-K6726 (1994). In addition, in order not to impair the effects of the present invention, other modified PVA or PV
When A is used in combination, the degree of polymerization of the other modified PVA or PVA is preferably within the above range.

The content of the above-mentioned specific modified PVA in the thermosensitive coloring layer is 100 parts by mass of the above electron-donating colorless dye.
From the standpoint of color density and offset printability (paper peeling, etc.),
It is preferably 30 to 300% by mass. The content of the specific modified PVA is 70 to 200% by mass.
Is more preferable, and 100 to 170 mass% is particularly preferable. The specific modified PVA according to the present invention contained in the heat-sensitive color forming layer can serve not only as an adhesive that enhances interlayer adhesion but also as a dispersant and a binder.

The sulfo-modified polyvinyl alcohol, diacetone-modified polyvinyl alcohol and acetoacetyl-modified polyvinyl alcohol preferably used as the specific modified PVA will be described in detail below.

The above-mentioned sulfo-modified polyvinyl alcohol is
Saponification of a polymer obtained by polymerizing an olefin sulfonic acid such as ethylene sulfonic acid, allyl sulfonic acid or methallyl sulfonic acid or a salt thereof and a vinyl ester such as vinyl acetate in an alcohol or an alcohol / water mixed solvent. Method, a method of copolymerizing amide sodium salt with a vinyl ester such as vinyl acetate, and saponifying the obtained copolymer, or treating PVA with bromine, iodine, etc., and then heating in an acidic sodium sulfite aqueous solution. It can be produced by a method of heating, a method of heating PVA in a concentrated aqueous solution of sulfuric acid, a method of acetalizing PVA with an aldehyde compound containing a sulfonic acid group, or the like.

The above-mentioned diacetone-modified polyvinyl alcohol is a partially or completely saponified product of a copolymer of a monomer having a diacetone group and a vinyl ester, and is obtained by copolymerizing a monomer having a diacetone group and a vinyl ester. It is produced by saponifying the obtained resin. In the diacetone-modified polyvinyl alcohol, the content of the monomer having a diacetone group (repeating unit structure) is not particularly limited.

The above-mentioned acetoacetyl-modified polyvinyl alcohol is generally a solution of polyvinyl alcohol resin,
It can be produced by adding and reacting liquid or gaseous diketene to the dispersion or powder. The degree of acetylation of the acetoacetyl-modified polyvinyl alcohol can be appropriately selected depending on the quality of the intended heat-sensitive recording material.

(Sensitizer) The heat-sensitive recording material of the present invention contains 2-benzyloxynaphthalene, dimethylbenzyl oxalate, m-terphenyl, as a sensitizer in the heat-sensitive color forming layer.
1 of ethylene glycol tolyl ether, p-benzyl biphenyl and 1,2-diphenoxymethylbenzene
It is preferable to include one or more species. 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.

In addition to the above-mentioned sensitizers, other sensitizers may be used in combination in the thermosensitive coloring layer according to the present invention as long as the effects of the present invention are not impaired. When other sensitizers are included, it is preferable that the sensitizers account for 50% by mass or more, and preferably 70% by mass or more of the total sensitizers.

Other sensitizers mentioned above include aliphatic monoamides, stearyl urea, p-benzyl biphenyl, di (2-methylphenoxy) ethane, di (2-methoxyphenoxy) ethane, β-naphthol- (p-methyl). Benzyl) ether, α-naphthyl benzyl 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- (chloro Phenoxy) 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 can be mentioned.

(Image Stabilizer) Furthermore, 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,
A hindered phenol compound is particularly effective, for example, 1,1,3-tris (2-methyl-4-hydroxy-t).
ert-butylphenyl) butane, 1,1,3-tris (2-ethyl-4-hydroxy-5-cyclohexylphenyl) butane, 1,1,3-tris (3,5-di-t)
ert-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-te)
(rt-butylphenol) and the like.

(Crosslinking Agent) Further, the thermosensitive color developing layer may contain a crosslinking agent which acts on the specific modified PVA used for the adhesive or the like. By containing the crosslinking agent in the thermosensitive coloring layer, the water resistance of the thermosensitive recording material of the present invention can be improved. As the cross-linking agent, any one capable of cross-linking the specific modified PVA can be appropriately used, but an aldehyde compound such as glyoxal and a dihydrazide compound such as adipic acid dihydrazide are particularly preferable. The content of the cross-linking agent is preferably 1 to 50 parts by mass, and more preferably 3 to 20 parts by mass with respect to 100 parts by mass of polyvinyl alcohol contained in the thermosensitive color developing layer and to be cross-linked. The content of the crosslinking agent is the above-mentioned specific modified PVA.
With respect to 1 to 50 parts by mass, the water resistance is preferable.

In the present invention, an electron-donating colorless dye,
Dispersion of the electron-accepting compound, the sensitizer and the like can be carried out in the above-mentioned adhesive and further 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 during 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 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, various pigments, metal soaps, waxes, surfactants,
An antistatic agent, an ultraviolet absorber, an antifoaming agent, a fluorescent dye, etc. may be added.

The above-mentioned pigments include calcium carbonate, barium sulfate, lithopone, wax stone, kaolin, calcined kaolin,
Amorphous silica and aluminum hydroxide are used.
As the metal soap, higher fatty acid metal salts are used, such as zinc stearate, calcium stearate, and aluminum stearate.

As the above wax, paraffin wax, microcrystalline wax, carnauba wax, methylol stearamide, polyethylene wax, polystyrene wax and fatty acid amide wax may be used alone or in combination. As the surfactant, a sulfosuccinic acid-based alkali metal salt, a fluorine-containing surfactant or the like is used.

(Mordant) Further, the thermosensitive coloring layer may contain a mordant. By containing the mordant in the thermosensitive coloring layer, bleeding of the thermosensitive recording material of the present invention due to inkjet recording can be prevented.

The mordant is selected from an amide group, an imide group, a primary amino group, a secondary amino group, a tertiary amino group, a primary ammonium salt group, a secondary ammonium salt group, a tertiary ammonium salt group and a quaternary ammonium salt group. Which is a compound containing at least one kind of cation group, and specific examples thereof include polyamide epichlorohydrin, polyvinylbenzyltrimethylammonium chloride, polydiallyldimethylammonium chloride, polymethacryloyloxyethyl-β-hydroxyethyldimethylammonium chloride, polydimethylamino. Ethylmethacrylate hydrochloride, polyethyleneimine, polyallylamine, polyallylamine hydrochloride, polyamide-polyamine resin, chaotic starch, dicyandiamide formalin condensate, dimethy And the like-2-hydroxypropyl ammonium salt polymers. The molecular weight of these compounds is preferably about 1,000 to 200,000. If the molecular weight is less than 1000, the water resistance tends to be insufficient, and if it is 200,000 or more, the viscosity becomes high, and the handling suitability may be poor.

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, etc., 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 thermosensitive coloring layer is not limited,
Usually, the dry weight is preferably about ² to 7 g / m ² .

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 latexes such as styrene-butadiene rubber latex, acrylonitrile-butadiene rubber latex, methyl acrylate-butadiene rubber latex, and vinyl acetate emulsion are used. be able to.

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, dihydrazide compounds such as adipic acid dihydrazide, and the like.

[0057]

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.
Moreover, the average particle diameter was measured using LA-500 (manufactured by Oliver).

[Example 1] << Formation of thermosensitive recording material >><Preparation of coating liquid for thermosensitive color developing layer> (Preparation of dispersion liquid A) The following components were mixed while being dispersed by a ball mill to give an average particle diameter of 0. A dispersion A of 0.6 μm was obtained. [Dispersion A composition] 2-anilino-3-methyl-6-diethylaminofluorane 10 parts (electron-donating colorless dye) 50% sulfo-modified polyvinyl alcohol solution 50 parts (Gauceran L-3266, saponification degree) 88 mol%, degree of polymerization 300, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.

(Preparation of Dispersion Liquid B) The following components were mixed while being dispersed by a ball mill to obtain a dispersion liquid B having an average particle diameter of 0.6 μm. [Dispersion B composition] 4-hydroxybenzenesulfonanilide 20 parts (electron-accepting compound) -sulfo-modified polyvinyl alcohol 2.5% solution 100 parts (Gocelan L-3266, saponification degree 88 mol%, polymerization degree 300, Made by Nippon Synthetic Chemical Industry Co., Ltd.

(Preparation of Dispersion C) The following components were mixed while being dispersed by a ball mill to obtain Dispersion C having an average particle size of 0.6 μm. [Dispersion C composition] -20 parts of 2-benzyloxynaphthalene (sensitizer) 100% solution of sulfo-modified polyvinyl alcohol100 parts (Gauceran L-3266, saponification degree 88 mol%, polymerization degree 300, sulfo modification Polyvinyl alcohol, manufactured by Nippon Synthetic Chemical Industry 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 2.0 μm.
A pigment dispersion D of m was obtained. [Pigment dispersion D composition] -Light calcium carbonate 40 parts-Sodium polyacrylate 1 part-Water 60 parts

A compound having the following composition was mixed to obtain a coating solution for a thermosensitive color developing layer. [Coating liquid composition for thermosensitive color developing layer] -Dispersion A 60 parts-Dispersion B 120 parts-Dispersion C 120 parts-Pigment dispersion D 101 parts-Zinc stearate 30% dispersion 15 parts-Paraffin wax (30% ) 15 parts ・ Sodium dodecylbenzene sulfonate (25%) 4 parts

<Preparation of Coating Liquid for Undercoat Layer> 20 parts of SBR (styrene-butadiene latex) and oxidized starch (25%) were mixed by stirring with a dissolver using the following composition.
And 25 parts were added to obtain a coating liquid for undercoat layer. -Calcined kaolin (oil absorption 75ml / 100g) 100 parts-Sodium hexametaphosphate 1 part-Distilled water 110 parts

<Formation of Thermosensitive Recording Material> JIS-P811
The smoothness specified in 9 is 150 seconds, and the basis weight is 50 g / m ^2.
On the base paper of No. 1, a coating solution for undercoat layer was applied by a blade coater so that the applied amount after drying was 8 g / m ² .
After the layer was dried, a calendering treatment was performed to produce an undercoat base paper. By forming the undercoat layer,
The smoothness of the undercoat base paper specified by JIS-P8119 was 350 seconds. 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 The sulfo-modified polyvinyl alcohol used in dispersions A, B and C in Example 1 was replaced with diacetone-modified polyvinyl alcohol (D-50).
A thermosensitive recording material according to Example 2 was obtained in the same manner as in Example 1 except that 0, saponification degree 98.5 mol%, polymerization degree 500, Unitika Ltd. was used.

Example 3 The sulfo-modified polyvinyl alcohol used in the dispersions A, B and C in Example 1 was converted to an acetoacetyl-modified polyvinyl alcohol (Gosephimmer Z200, saponification degree 98.5 mol%, polymerization degree). A heat-sensitive recording material according to Example 3 was obtained in the same manner as in Example 1, except that the temperature was changed to 1000, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.

[Example 4] A thermosensitive recording material according to Example 4 was obtained in the same manner as in Example 1 except that the coating liquid for the thermosensitive coloring layer was applied by the air knife coater.

Example 5 The sulfo-modified polyvinyl alcohol used in the dispersions A, B and C in Example 1 was converted to an acetoacetyl-modified polyvinyl alcohol (Gosephimmer Z200, saponification degree 98.5 mol%, polymerization degree). 1000, changed to Nippon Synthetic Chemical Industry Co., Ltd.
The hard calcium carbonate used in Pigment Dispersion D is amorphous silica (Mizukasil P-78A, manufactured by Mizusawa Chemical Industry Co., Ltd.).
A thermosensitive recording material according to Example 5 was obtained in the same manner as in Example 1 except for the above.

[Example 6] A thermosensitive recording material according to Example 6 was obtained in the same manner as in Example 5 except that the composition of the coating liquid for the thermosensitive coloring layer in Example 5 was changed as shown below. [Coating liquid composition for thermosensitive color developing layer] -Dispersion A 60 parts-Dispersion B 120 parts-Dispersion C 120 parts-Pigment dispersion D 101 parts-Zinc stearate 30% dispersion 15 parts-Paraffin wax (30% ) 15 parts sodium dodecylbenzenesulfonate (25%) 4 parts polyamide epichlorohydrin 40 parts (Arafix 300, manufactured by Arakawa Chemical Industry Co., Ltd.)

[Comparative Example 1] The sulfo-modified polyvinyl alcohol used in the dispersions A, B and C in Example 1 was converted to polyvinyl alcohol (PVA-110, saponification degree 98.5 mol%, polymerization degree 1000, (stock). ) A thermal recording material according to Comparative Example 1 was obtained in the same manner as in Example 1 except that the material was changed to Kuraray.

Comparative Example 2 Polyvinyl alcohol (PVA-405, saponification degree 80 mol%, polymerization degree 500, Kuraray Co., Ltd.) was used as the sulfo-modified polyvinyl alcohol used in dispersion liquids A, B and C in Example 1. A heat-sensitive recording material according to Comparative Example 2 was obtained in the same manner as in Example 1 except that it was changed to (Production).

[Comparative Example 3] The sulfo-modified polyvinyl alcohol used in the dispersions A, B and C in Example 1 was replaced with polyvinyl alcohol (PVA-417, saponification degree 80 mol%, degree of polymerization 1750, Kuraray Co., Ltd.). A heat-sensitive recording material according to Comparative Example 3 was obtained in the same manner as in Example 1 except that the heat-sensitive recording material was manufactured.

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

Comparative Example 5 Dispersion C in Example 1
4-hydroxybenzenesulfonanilide is added
Example 1 except that p-N-benzylsulfamoylphenol (N-benzyl-4-hydroxybenzenesulfonamide) of Example 2 of JP-A-207922 was changed.
A thermal recording material according to Comparative Example 5 was obtained in the same manner as in.

<Evaluation> Table 1 shows the evaluation results of the thermal recording materials obtained in Examples 1 to 6 and Comparative Examples 1 to 5. The sensitivity, background fog, image storability, printability, inkjet printability, and inkjet ink resistance in the table were evaluated as follows.

(1) Sensitivity Kyocera Corp. thermal head (KJT-216-8M)
PD1) and a thermal printer having a pressure roll of 100 kg / cm ² immediately before the head were used to print on the thermal recording materials obtained in Examples 1 to 6 and Comparative Examples 1 to 5. The printing was performed with a pulse width of 1.5 ms under the conditions of a head voltage of 24 V and a pulse period of 10 ms, and the printing density was measured with a Macbeth reflection densitometer (RD-918).

(2) Background Fogging The heat-sensitive recording materials obtained in Examples 1 to 6 and Comparative Examples 1 to 5 were used in an environment of 60 ° C. and 30% relative humidity for 24 hours.
After leaving the surface for a while, the Macbeth reflection densitometer (RD-
918). The lower the value, the better the result.

(3) Image storability Images were recorded on the thermosensitive recording materials obtained in Examples 1 to 6 and Comparative Examples 1 to 5 by 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 30% humidity. After that, the image density was measured by a Macbeth reflection densitometer (RD-9
18), and the residual ratio with respect to the image density of the untreated product on which an image was recorded under the same apparatus and conditions as in (1) above was calculated from the following formula. The higher the value, the better the image storability. Image storability (%) = (image density after leaving / image density of unprocessed product) × 100

(4) Printability (printing strength) The thermal recording materials obtained in Examples 1 to 6 and Comparative Examples 1 to 5 using an RI tester (RI-3 type, manufactured by Akira Seisakusho Co., Ltd.) 1 g of the ink (SMX Tuck Great Ink 15, manufactured by Toka Co., Ltd.) was transferred to. Then, the peeled state of the surface of the recording surface of each heat-sensitive recording material was visually observed and evaluated according to the following criteria. [Standard] A: The recording surface is not peeled at all. ◯: Recording surface is slightly peeled off, but good. X: The recording surface was peeled off and there was a problem in practical use.

(5) Inkjet printing suitability The thermal recording materials obtained in Examples 1 to 6 and Comparative Examples 1 to 5 were red-colored in super fine mode using an inkjet printer (MJ930 manufactured by Seiko Epson Corp.). Was printed and the degree of bleeding was evaluated.・ Bleed ◎: Characters can be read clearly. ◯: Characters are blurred, but there is no problem in reading. Δ: Characters are blurred and difficult to read, but legible. X: Characters are blurred and cannot be read.

(6) Inkjet ink resistance An image obtained by printing a high quality image on the thermal recording materials obtained in Examples 1 to 6 and Comparative Examples 1 to 5 with an inkjet printer (MJ930C manufactured by Seiko Epson Corp.),
A thermal recording surface printed in the same manner as in the case of the above (1) sensitivity was brought into contact (contact), and the image density after standing treatment at 25 ° C. for 48 hours was Macbeth reflection densitometer (RD-918).
It was measured at. 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.

[0082]

[Table 1]

As is clear from Table 1, a heat-sensitive recording material containing 4-hydroxybenzenesulfonanilide as an electron-accepting compound and containing a specific modified polyvinyl alcohol as an adhesive was found to have sensitivity, background fogging and image preservation. It was found that both the printability and printability were excellent.
In particular, it was found that the thermal recording materials according to Examples 1 to 6 were excellent in image storability and printability as compared with the thermal recording materials according to Comparative Example 1 containing PVA which was not the specific modified PVA. On the other hand, Comparative Examples 2 and 3 using PVA having a saponification degree of less than 85 mol% were inferior in sensitivity, background fog, image storability and printability. Further, the heat-sensitive recording material according to Comparative Example 3 using bisphenol A as the electron-accepting compound was significantly inferior in image storability. Furthermore, in Comparative Example 4 using a sulfonamide compound different from the sulfonamide compound of the present invention, the sensitivity, background fog and image storability were poor.

Further, the heat-sensitive recording materials according to Examples 5 and 6 were excellent in ink jet recording suitability because amorphous silica was used as an inorganic pigment in the exothermic coloring layer or a mordant was contained. Further, it was found that the thermal recording materials according to Examples 1 to 6 have excellent ink jet ink resistance.

[0085]

As described above, according to the present invention, the thermosensitive coloring layer contains 4-hydroxybenzenesulfonanilide as an electron-accepting compound, and further, as an adhesive,
By containing a specific modified polyvinyl alcohol, it is possible to provide a heat-sensitive recording material having high sensitivity and less background fog as compared with a conventional heat-sensitive recording material, and having excellent image preservability and printability such as offset printing. be able to.
Further, the present invention can provide a thermal recording material having excellent inkjet printability and inkjet ink resistance.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hirofumi Mitsuo             200, Onakazato, Fujinomiya City, Shizuoka Prefecture Fuji Photo             Within Film Co., Ltd. F term (reference) 2H026 BB24 DD43 DD53 FF01

Claims (3)

[Claims] 1. A thermosensitive 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 serves as the electron-accepting compound. -Heat-sensitive recording characterized by containing hydroxybenzenesulfonanilide and at least one modified polyvinyl alcohol selected from sulfo-modified polyvinyl alcohol, diacetone-modified polyvinyl alcohol and acetoacetyl-modified polyvinyl alcohol as an adhesive. material. 2. The content of the modified polyvinyl alcohol is 7 parts by weight based on 100 parts by mass of the electron-donating colorless dye.
The heat-sensitive recording material according to claim 1, wherein the content is 0 to 200% by mass. 3. The modified polyvinyl alcohol has a saponification degree of 85 to 99 mol% and a polymerization degree of 200 to 2000.
The heat-sensitive recording material according to claim 1 or 2, wherein