JPH02265787A - Thermal recording material - Google Patents

Abstract

PURPOSE:To obtain a thermal recording material excellent in the reproducibility of a printing pixel even in any region from low density to high density and capable of obtaining a recording image of high image quality by providing an intermediate layer composed of a specific composition between a support and a recording layer. CONSTITUTION:An intermediate layer based on pigment having oil absorbancy of 80ml/100g or more and silicon modified polyvinyl alcohol is provided between a support and a recording layer. This silicon modified polyvinyl alcohol forms a reaction product along with various inorg. pigments to markedly enhance strength. The silicon modified polyvinyl alcohol to be used has a polymerization degree of 400-2800 and a saponification degree of 70-99% and is pref. within a range of 0.1-5mol.% as a silicon-containing monomer unit. A thermal recording layer is applied to the intermediate layer thus formed and dried to prepare a thermal recording material.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a heat-sensitive recording medium, and particularly to a heat-sensitive recording medium that has excellent print pixel reproducibility, high recording density, and excellent surface strength.

[Prior Art] Conventionally, heat-sensitive recording utilizes a coloring reaction between a coloring agent and a coloring agent that develops color when it comes into contact with the coloring agent, and a colored image is obtained by bringing both coloring materials into contact with each other using heat. The body is well known. Such heat-sensitive recording media are relatively inexpensive, and the recording equipment is compact and relatively easy to maintain.
It is used not only as a recording medium for facsimiles and various computers, but also in a wide range of fields.

As the applications have become more diverse, thermal recording materials have excellent reproducibility of printed pixels in all areas from low density to high density, and can produce recorded images of high quality comparable to silver halide photography. The demand for this is increasing. Furthermore, as recording equipment becomes faster, there is an increasing demand for heat-sensitive recording materials with excellent dynamic recording sensitivity.

In order to obtain such a high-sensitivity, high-quality thermal recording medium,
An intermediate layer made of an oil-absorbing pigment is provided (Japanese Patent Laid-Open No. 59-1
55097, 61-44683), and a method of combining these layers into multiple layers to improve smoothness and heat insulation (JP-A-61-11286, JP-A-61-19388).
No. 0) etc. have been proposed.

However, when inorganic pigments with high oil absorption properties such as amorphous silica or calcined clay are used as oil absorption pigments,
Since the surface area becomes large, the strength of the paper surface decreases. Furthermore, when the content of the binder is increased to increase the strength, the recording density is significantly reduced.

[Problem that the invention seeks to solve]

The object of the present invention is to provide a thermal recording medium which does not have the above-mentioned drawbacks (and which has excellent reproducibility of printed pixels in any range from low density to high density, and which can obtain recorded images of high quality). [Means for Solving the Problems] The above objects of the present invention are achieved by providing an intermediate layer having a specific composition between the support and the recording layer.

Accordingly, the present invention provides a heat-sensitive recording material in which a heat-sensitive recording layer is provided on a support, and a pigment having an oil absorption of 80 ml/100 g or more and silicon-modified polyvinyl are disposed between the support and the recording layer. This heat-sensitive recording material is characterized by having an intermediate layer containing alcohol as a main component.

[Effect]

As described above, the heat-sensitive recording material of the present invention is characterized in that an intermediate layer mainly composed of a pigment with an oil absorption of 80 ml/100 g or more and silicon-modified polyvinyl alcohol is provided between the support and the recording layer. However, this silicon-modified polyvinyl alcohol forms a reactant with various inorganic pigments, and its strength is significantly improved. Among them, amorphous silica, aluminum silicate, calcined clay, and the like are preferably used because of their excellent reaction with Si and AI. However, when the amount of silicon-modified polyvinyl alcohol is increased, the oil absorption and heat retention of the undercoat decrease, resulting in head scum and a decrease in recording density. Therefore, the content is 1 to 50 parts per 100 parts of pigment.
The amount is preferably about 1 part, and more preferably 2 to 30 parts.

Further, the silicon-modified polyvinyl alcohol preferably used in the present invention has a degree of polymerization of 400 to 2,800 and a degree of saponification of 70.
0.1 to 5 as a monomer unit containing ~99% silicon
The preferred range is mole %.

As mentioned above, silicon-modified polyvinyl alcohol exhibits specific effects, but in addition to the above-mentioned inorganic pigments, other pigments such as talc, light calcium carbonate, and amine resins, phenolic resins, and polystyrene resins are also used as pigments. It is also possible to use various inorganic and organic pigments.

Examples of binders that can be used in combination with silicon-modified polyvinyl alcohol include starch, casein, polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, water-soluble polymers such as polyacrylic acid, styrene-butadiene copolymers, and styrene.・Acrylic acid copolymer, acrylonitrile-butadiene copolymer, colloidal silica particle composite styrene・
Examples include various synthetic resin emulsions such as acrylic acid ester copolymers and acrylic acid copolymers.

It is also possible to provide two or more intermediate layers.

The coating amount of the intermediate layer is preferably such that the thickness of the intermediate layer is approximately 5 to 40 μm.

The heat-sensitive recording layer of the present invention is produced by coating and drying the heat-sensitive recording layer on the intermediate layer thus formed. However, regarding the combination of the coloring agent and the coloring agent contained in the recording layer, are not particularly limited, and any combination can be used as long as the two come into contact with each other due to heat and cause a coloring reaction.For example, a colorless or light-colored basic dye and an inorganic or organic acidic substance can be used. Examples include a combination with a higher fatty acid metal salt such as ferric stearate and a phenol such as gallic acid. Furthermore, it is also possible to apply the present invention to various heat-sensitive recording bodies in which a recorded image is obtained by heat, such as a heat-sensitive recording body in which a diazonium compound, a coupler, and a basic substance are combined.

However, the specific intermediate layer of the present invention provided on the support exhibits an excellent effect particularly in combinations of basic dyes and acidic substances, and is therefore particularly preferably applied to such combinations.

In the heat-sensitive recording material of the present invention, various colorless or light-colored basic dyes are known as the colorless or light-colored basic dyes that constitute the recording layer together with a specific coloring agent and a thermofusible substance. Ru.

3.3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide, 3.3-bis(p-dimethylaminophenyl)phthalide, 3-(p-dimethylaminophenyl)-3-(1,2 -dimethylindol-3-yl)phthalide, 3-(P-dimethylaminophenyl)-
3-(2-methylindol-3-yl)phthalide, 3
．． 3-bis(1,2-dimethylindol-3-yl)
-5-dimethylaminophthalide, 3,3-bis(12-
dimethylindol-3-yl)-6-dimethylaminophthalide, 3,3-bis(9-ethylcarbazole-3
-yl)-6-dimethylaminophthalide, 3.3-bis(2-phenylindol-3-yl)-6-dimethylaminophthalide, 3-p-dimethylaminophenyl-3
-(1-methylpyrrol-3-yl)-6-dimethylaminophthalide and other triallylmethane dyes, 4,4'-
Bis-dimethylaminobenzhydrylbenzyl ether, N-herophenyl leukoolamine N-2,4,5
-) Diphenylmethane dyes such as dichlorophenyl leuco auramine, benzoyl leucomethylene blue, P-
Thiazine dyes such as nitrobenzoylleucomethylene blue, 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3-phenyl-spiro-
Spiro dyes such as dinaphthopyran, 3-benzyl-spiro-dinaphthopyran, 3-methyl-naphtho(6'-methoxybenzo)spiropyran, 3-propyl-spiro-dibenzopyran, rhodamine-B-anilinolactam, rhodamine (p- Lactam dyes such as nitroanilino)lactam, rhodamine (0-chloroanilino)lactam,
3-Dimethylamino-7-methoxyfluorane, 3-diethylamino-6-methoxyfluorane, 3-diethylamino-7-methoxyfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-6-methyl-7 -Chlorofluorane, 3-diethylamino-6
, 7-dimethylfluorane, 3-(N-ethyl-p-)
Luidino)-7-methylfluorane, 3-diethylamino-7-N-acetyl-N-methylaminofluorane,
3-diethylamino-7-N-methylaminofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3-diethylamino-7-(N-methyl-N-benzylamino)fluorane, 3-diethylamino-7-(
N-chloroethyl-N-methylamino)fluorane, 3
-diethylamino-7-N-diethylaminofluorane, 3-(N-ethyl-p-)luidino)-6-methyl-7-phenylaminofluorane, 3-(N-ethyl-
p-Toluidino)-6-methyl-7-(p-toluidino)fluoran, 3-diethylamino-6-methyl-7-
Phenylaminofluorane, 3-dibutylamino-6-
Methyl-7-phenylaminofluorane, 3-diethylamino-7-(2-carbomethoxy-phenylamino)
Fluoran, 3-(N-ethyl-N-isoamyl)amino-6-methyl-7-phenylaminofluoran, 3-
(N-cyclohexyl-N-methylamino)-6-methyl-7-phenylaminofluorane, 3-pyrrolidino-
6-methyl-7-phenylaminofluorane, 3-piperidino-6-methyl-7-phenylaminofluorane,
3-diethylamino-6-methyl-7-xylidinofluorane, 3-diethylamino-7-(o-chlorophenylamino)fluoran, 3-dibutylamino-7-(o
-chlorophenylamino)fluorane, 3-(N-ethyl-N-tetrahydrofurfuryl)amino-6-methyl-7-phenylaminofluorane, 3-(N-methyl-
N-n-propyl)amino-6-methyl-7-phenylaminofluorane, 3-pyrrolidino-6-methyl-7-
P-butylphenylaminofluorane, 3-(N-ethyl-N-n-brobyl)amino-6-methyl-7-phenylaminofluorane, 3-(N-ethyl-N-isobutyl)amino-6-methyl -7-phenylaminofluorane, 3-(N-methyl-Nn-hexylamino-6
-Methyl-7-phenylaminofluorane, 3-(N-
Ethyl-Nn-hexyl)amino-6-methyl-7-
Fluoran dyes such as phenylaminofluoran, 3-(N-ethyl-N-cyclopentyl)amino-6-methyl-7-phenylaminofluoran, etc., are of course not limited to these dyes, and two types can be used. It is also possible to use the above dyes in combination.

In the present invention, the coloring agent constituting the recording layer of the heat-sensitive recording medium is not particularly limited, and the coloring agent has the property of liquefying, vaporizing, or dissolving with an increase in temperature, and the above-mentioned basic coloring agent Various substances are used that have the property of causing coloration when they come into contact with dyes. Typical specific examples include activated clay, acid clay, acupulgite, bentonite, colloidal silica, inorganic acidic substances such as aluminum silicate, 4-tert-butylphenol, 4-hydroxyphenoxide, alpha-naphthol, beta
-naphthol, 4-hydroxyacetophenol, 4-
tert-octylcatechol, 2.2'-dihydroxydiphenol, 2.2'-methylenebis(4-methyl-6-tert-isobutylphenol), 4.4'-isopropylidenebis(2-tert-butylphenol), 4 .4'-5ec-butylidenediphenol, 4-phenylphenol, 4.4'-isopropylidenediphenol, 2.2'-methylenebis(4-chlorophenol), hydroquinone, 4.4°-cyclohexylidenediphenol , benzyl 4-hydroxybenzoate, dimethyl 4-hydroxyphthalate, hydroxymonobenzyl ether, 4-hydroxy-4'-isopropyloxydiphenyl sulfone, 3'4"tetramethylene-4-hydroxydiphenyl sulfone, 4.
4'-(1,3-dimethylbutylidene)bisphenol, 4.4'-(1-phenylethylidene)bisphenol, 4.4''-(p-phenylenediisopropylidene)diphenol, 4.4'-(m Phenolic compounds such as -phenylene diisopropylidene) diphenol, novolak type phenolic resin, phenol polymer, benzoic acid, p-Lert-butylbenzoic acid, trichlorobenzoic acid, terephthalic acid, 3-sec-butyl-4 -Hydroxybenzoic acid, 3-cyclohexyl-4-hydroxybenzoic acid, 3.5-dimethyl-4-hydroxybenzoic acid,
salicylic acid, 3-isopropylsalicylic acid, 3-tar
t-butylsalicylic acid, 3-benzylsalicylic acid, 3-
(alfa-methylbenzyl)salicylic acid, 3-chloro-5-(alfa-methylbenzylsalicylic acid, 3.
Aromatic carboxylic acids such as 5-di-tert-7'tylsalicylic acid, 3-phenyl-5-(alfa, alfa-dimethylbenzyl)salicylic acid, 3,5-di-alfa-methylbenzylsalicylic acid, and these phenolic compounds, aromatic Group carboxylic acids such as zinc, magnesium, aluminum, calcium, titanium, manganese,
Salts with polyvalent metals such as tin and nickel, and even zinc,
Examples include organic acidic substances such as complex compounds of salts of polyvalent metals such as magnesium, aluminum, calcium, titanium, manganese, tin, and nickel and organic compounds such as antipyrine, pyridine, and demethylaminoantipyrine. The proportion of the coloring agent and basic dye in combination is not necessarily limited, but is 100 to 700 parts by weight, more preferably 15 parts by weight, based on 100 parts by weight of the basic dye.
0 to 400 parts by weight of coloring agent is blended. Note that, of course, two or more coloring agents may be used in combination as necessary.

Coating liquids containing these materials are generally prepared by using water as a dispersion medium.
It is prepared by dispersing the dye, the coloring agent, and the thermofusible substance represented by the general formula (1) together or separately using a stirring/pulverizing machine such as a ball mill, attritor, or sand mill.

Such coating liquids usually contain starches and binders as binders.
Hydroxyethylcellulose, methylcellulose, carboxymethylcellulose, gelatin, casein, gum arabic, polyvinyl alcohol, styrene/maleic anhydride copolymer salt, styrene/acrylic acid copolymer salt, styrene/butadiene copolymer emulbutane, etc. are all solids. 10 to 40% by weight, preferably 15 to 30% by weight.

Furthermore, various auxiliary agents can be added to the coating solution, such as dispersants such as sodium dioctyl sulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate, fatty acid metal salts, and triazoles. Examples include ultraviolet absorbers such as UV absorbers, antifoaming agents, fluorescent dyes, and colored dyes. In addition, dispersions of stearic acid, polyethylene carnauba wax, paraffin wax, zinc stearate, calcium stearate, ester wax, etc., emulzidine, etc. should be added to prevent sticking of the heat-sensitive recording material due to contact with recording equipment or recording heads. You can also do it.

Further, fatty acid amides such as stearic acid amide, stearic acid methylene bisamide, oleic acid amide, valmitic acid amide, coconut fatty acid amide, 2,2'-methylene bis(4
-methyl-6-tert-butylphenol), 1,1
．． 3-tris(2-methyl-4-hydroxy-5ter
Hindered phenols such as t-butylphenyl)butane, 12-bis(phenoxy)ethane, 1,2-bis(
Ethers such as 4-methylphenoxy)ethane, 1,2-bis(3-methylphenoxy)ethane, 2-naphtholbenzyl ether, dibenzyl terephthalate, 1-
It is also possible to use various known thermofusible substances such as esters such as hydroxy-2-naphthoic acid phenyl ester.

In addition, inorganic pigments such as kaolin, clay, talc, calcined calcium carbonate clay, titanium oxide, diatomaceous earth, fine particulate anhydrous silica, and activated clay may be added to improve the adhesion of residue to the recording head.

In the present invention, there are no particular limitations on the method of forming the recording layer.
It is formed by applying a coating liquid onto the intermediate layer and drying it. Further, the amount of the coating liquid to be applied is not particularly limited, and is usually 2 to 12 g/rrl in terms of dry weight, preferably 3 to 10 g/rrl.
It is in the range of about 0.

In addition, the support is not particularly limited, and papers such as high-quality paper, base paper made with a Yankee machine, single-sided glossy base paper, double-sided glossy base paper, cast coated paper, art paper, coated paper, medium-quality coated paper, etc. Synthetic fiber paper, synthetic resin film, etc. are used as appropriate.

Incidentally, after coating and drying the intermediate layer and the recording layer, smoothing treatment such as super calendering may be performed as necessary. Furthermore, it is possible to provide an overcoat layer on the recording layer for the purpose of protecting the recording layer, etc., and various known techniques in the field of heat-sensitive recording materials can be added, such as providing a backing layer on the support. .

The thus obtained heat-sensitive recording material of the present invention has an intermediate layer mainly composed of a pigment with a specific oil absorption amount and silicon-modified polyvinyl alcohol between the support and the heat-sensitive recording layer. It is a heat-sensitive recording material that has excellent pixel reproducibility in all areas including density, high recording density, and excellent surface strength.

"Example" The present invention will be described in more detail with reference to Examples below, but the present invention is of course not limited to these.

Further, unless otherwise specified, parts and percentages in the examples indicate parts by weight and percentages by weight, respectively.

Amorphous silica of Example 1-1 (oil absorption 150ml/100g)
100 parts silicon-modified polyvinyl alcohol 10% aqueous solution (
Degree of polymerization 2000, degree of saponification 98% 30 parts Silicon content 0.3 mol%) 10 parts SBR latex (solid content: 50%) The above formulation was mixed to have a solid content of 30%.

'' Green mold 1 ■ Plate The obtained intermediate layer coating liquid-1 was applied to high-quality paper with a basis weight of 50 g/board using an air knife coater so that the coating amount after drying was 8 g/m (thickness 213 μm). Dry.

・゛■ Preparation of liquid A 3-(N-cyclohexyl-N-methylamino)-6-
Methyl-7-phenylaminofluorane
10 parts 1,2 Bis(4-methylphenoxy)ethane 20 parts Methylcellulose 5% aqueous solution 15 parts Water
80 parts of this composition was ground in a sand mill until the average particle size was 2 μm.

■ Preparation of Solution B 4. 30 parts of 4'-isopropylidenediphenol 5% aqueous solution of methylcellulose 30 parts of water
70 parts of this composition was ground in a sand mill until the average particle size was 2 μm.

125 parts of liquid A, 81130 parts, silicon oxide pigment (oil absorption 1
8hl/100g) 30 parts, 20% oxidized starch aqueous solution 1
A recording layer coating liquid was prepared by stirring and mixing 50 parts and 55 parts of water.

The obtained recording layer coating liquid was applied onto the intermediate layer using an air knife coater so that the coated amount after drying was 5 g/rrf, and dried to obtain a heat-sensitive recording paper.

Example 2 Example 1 except that calcined clay (85 ml/100 g) was used instead of the amorphous silica used in the composition of the intermediate layer coating liquid.
A thermosensitive recording paper was obtained in the same manner as above.

Example 3 A thermosensitive recording paper was obtained in the same manner as in Example 1 except that silicon-modified polyvinyl alcohol having a silicon content of 2.8 mol % was used.

Example 4 A thermosensitive recording paper was obtained in the same manner as in Example 1 except that 200 parts of silicon-modified polyvinyl alcohol was contained. Comparative Example 1 Clay (20 ml/10 Og) was used instead of amorphous silica.
A thermosensitive recording paper was obtained in the same manner as in Example 1 except that .

Comparative Example 2 A thermosensitive recording paper was obtained in the same manner as in Example 1 except that polyvinyl alcohol (degree of polymerization 1000, degree of saponification 98%) was used instead of silicon-modified polyvinyl alcohol.

The six types of thermal recording paper thus obtained were used in a thermal printer (SONY tlP-701 model, video printer).
was used to record the print pulse times of 3ms and 8ms,
The recorded density was measured with a Macbeth density needle (model RD-100R, using an amber filter), and the results are shown in the separate table. Also, the reproducibility of printing pixels (simply called reproducibility)
, cutting suitability, and head debris were evaluated, and the results are also listed in a separate table.

Attached Table Note that the reproducibility was evaluated by the ratio of the area of a printed dot to the area of one dot of the thermal head (dot reproduction rate), and the evaluation criteria were as follows.

O... 86% or more O... 76-85% Δ... 70-75% The evaluation was based on the generation of paper dust when cutting, and the evaluation criteria were as follows.

O: There was no generation of paper dust and no peeling of the recording layer.

O: No paper dust was generated, but there was slight peeling of the recording layer.

×: Significant generation of paper dust, and frequent peeling of the recording layer.

In addition, regarding head scraps, NEFAX-27 (NEFAX-27
(manufactured by Company C) was used to make an evaluation by looking at the head residue after 10 copies were made at a printing rate of 100%, and the evaluation criteria were as follows.

◎・・・No head dregs can be seen.

O... Head dregs are slightly visible.

×: Significant occurrence of head debris.

【effect〕

As is clear from the results in the attached table, the thermal recording medium of the present invention has excellent reproducibility of printed pixels in both low to high density regions, has a high recording density, and has excellent cutting suitability of the recording medium. It was a recording medium with excellent head residue.

Claims (3)

[Claims] (1) In a heat-sensitive recording material in which a heat-sensitive recording layer is provided on a support, an oil absorption amount of 80 ml/1 is provided between the support and the recording layer.
1. A heat-sensitive recording material comprising an intermediate layer mainly composed of a pigment of 0.00 g or more and silicon-modified polyvinyl alcohol. (2) Claim (1) characterized in that the pigment having an oil absorption of 80 ml/100 g or more is amorphous silica, aluminum silicate, or calcined clay.
The heat-sensitive recording medium described above. (3) The heat-sensitive recording material according to claim 1, wherein the silicon-modified polyvinyl alcohol is contained in an amount of 2 to 30 parts based on 100 parts of the pigment.