JPH02310083A - Thermal recording material - Google Patents

Abstract

PURPOSE:To impart high speed printing aptitude reduced in the adhesion of refuse and generating no printing trouble due to sticking by providing an under coat layer containing zirconyl ammonium carbonate to thermal recording paper wherein a thermal color forming layer is formed on a support. CONSTITUTION:An under coat layer containing zirconyl ammonium chloride is provided between a support and a thermal color forming layer. Zirconyl ammonium carbonate is used in a ratio of 1-50 pts., pref., 3-20 pts. by wt. of the adhesive in the under cost layer. When the amount of zirconyl ammonium carbonate is below 1 pts. wt., the effect preventing the adhesion of refuse and the generation of sticking is insufficient and, when said amount exceeds 50 pts. wt., sufficient satisfactory result can not be obtained in developed color density. Pigment, an adhesive, if necessary, a surfactant, a dispersant, a thickener, a water resistance imparting agent and a defoaming agent are contained in the under coat layer other than zirconyl ammonium carbonate. The coating amount of the under coat layer is set to 3-20g/m<2>. The support material is not especially limited.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a heat-sensitive recording material, and particularly to a heat-sensitive recording material with excellent continuous recording suitability.

[Prior art] Thermal recording method allows color images to be obtained simply by heating.
Further, it is preferred because the recording device can be made relatively simple and compact, and it is widely used as various information recording papers.

Particularly in recent years, improvements have been made in the equipment of thermal facsimiles and thermal printers that use such thermal recording materials, and high-speed recording, which was difficult in the past, has become possible. Such equipment,
As the speed of the hardware field increases, the heat-sensitive recording materials used are required to have improved recording sensitivity, and many proposals have been made in this regard.

These heat-sensitive recording materials are generally prepared by providing a single or multilayer heat-sensitive coloring layer containing a binder or a heat-colorable substance as a main component on a support such as paper, plastic film, or synthetic paper.

It is known that there are several problems when such a system is put into practical use. One is color-forming substances that are in a molten state when heated (color-forming agents such as leuco dyes and phenols).
Then, a thermofusible organic compound (composed of a so-called sensitizer) is transferred and adhered to the thermal head.

This phenomenon is called "scum adhesion," and it gradually accumulates during continuous recording.As a result, it impairs the adhesion between the thermal head and the thermosensitive coloring layer, reduces heat conduction, and reduces recorded image quality and recording density. It will bring about.

Another problem is that when heat is applied, the surfaces of the thermal head and the thermosensitive coloring layer become sticky or sticky. This phenomenon is called "stay soaking," and when this occurs, the snowy feeding of the heat-sensitive recording material is prevented, resulting in skipped recordings and image disturbances, and in extreme cases, the heat-sensitive coloring layer is It may stick to the head and make continuous recording impossible. In order for recording to be carried out smoothly and continuously, one of the conditions that the heat-sensitive recording material must satisfy is the absence of the above-mentioned scum and sticks.

In order to control this scum and stickiness, it is possible to reduce the amount of molten components that cause scum and stickiness in the heat-sensitive layer and increase the pigment blending ratio, but this goes against the demand for higher sensitivity associated with high-speed printing. However, although scum and stickiness can be suppressed, there is a problem in that sufficient color density cannot be obtained with low energy during high-speed printing. In addition, proposals to incorporate highly oil-absorbing pigments were made, for example, in Japanese Patent Publication No. 61-5611.
Although this method was disclosed in Publication No. 8, it was still insufficient to meet the demands for higher sensitivity accompanying higher speeds, such as lower print density.

[Problems to be Solved by the Invention] An object of the present invention is to provide a heat-sensitive recording material that has excellent suitability for high-speed printing and has little adhesion of residue and no printing problems due to sticking.

A further object of the present invention is to provide such an excellent heat-sensitive recording material without providing any protective layer.

[Means for Solving the Problems] As a result of repeated research to achieve the above object, the present inventors have developed an undercoat containing zirconyl ammonium carbonate between the support and the heat-sensitive coloring layer in a heat-sensitive recording material. The present inventors have discovered that by providing a layer, it is possible to obtain a heat-sensitive recording material that is free from adhesion of residue and sticking to a thermal head due to a heat-sensitive coloring layer, without degrading various qualities related to recording, and has completed the present invention.

In order to avoid the occurrence of the phenomenon of sticking without providing a protective layer, the present inventors have developed a method for preparing the undercoat layer that may have negative effects such as agglomeration of the paint and a decrease in sensitivity. 3 = Research was carried out with the idea of adding additives that exhibit excellent properties of sticking, preventing sticking, and preventing scum (=J adhesion).As a result, among various substances, zirconyl ammonium carbonate ((NH) ) We have completed the present invention by discovering that Zr0(COs)2) is a substance that exhibits particularly remarkable effects.

Even if it is a zirconium compound, other than zirconyl ammonium carbonate, for example, zirconium acid chloride (Z r OC
, 17・8H20), zirconyl sulfate (ZroSO-
nH2O), zirconyl nitrate (ZrO(NO) ・n
H2O), zirconyl acetate (ZrO(C2H302)2
) and other zirconium compounds tend to cause aggregation and thickening of the paint, have a poor effect on desired scum and sticks, and may cause a decrease in sensitivity, so they are not suitable for solving the present problem.

The reason why zirconyl ammonia carbonate has a particularly remarkable effect is not necessarily clear so far, but
Since the paint is on the p++ or alkaline side, it is possible to make the paint stably, and because gases such as ammonia and carbon dioxide are generated during coating drying, the porosity of the undercoat layer is increased and the scum is removed from the undercoat layer. In addition to increasing absorption capacity, reactions with adhesives and molten components are thought to contribute in some way.

JP-A-61-0585 proposes providing a protective layer on a heat-sensitive coloring layer containing a zirconium compound. However, the object of the present invention is not to provide a protective layer on the heat-sensitive coloring layer, and this proposal cannot solve the problems of the present invention. In other words, if a protective layer is present, heat transfer from the thermal head to the thermosensitive coloring layer is inhibited by the intervening protective layer, resulting in inappropriate color density during high-speed printing. Since the anti-dust adhesion and anti-sticking effects are inhibited, the effects will not appear at all.Therefore, this proposal does not solve the problem of the present invention, and there is still no way to find a heat-sensitive recording material that has excellent functions and effects. It was desired.

= 6- In the present invention, zirconyl ammonium carbonate is mixed into a coating liquid for forming an undercoat layer.

In the same coating, zirconyl ammonium carbonate is contained in the undercoat layer in an amount of 1 to 50 parts by weight, preferably 3 to 50 parts by weight, based on the adhesive in the undercoat layer.
It is used in a proportion of 20 parts by weight. If it is less than 1 part by weight, the effect of preventing the occurrence of dregs and sticking will not be sufficient, while if it exceeds 50 parts by weight, the color density will not be satisfactory.

The undercoat layer may contain an external pigment of zirconyl ammonium carbonate, an adhesive, and, if necessary, a surfactant, a dispersant, a thickener, a waterproofing agent, an antifoaming agent, and the like.

As the pigment for the underlayer, a wide range of inorganic and organic pigments can be used without any restriction on oil absorption.

Specifically, calcined kaolin, kaolin, talc, barium sulfate, titanium oxide, light calcium carbonate, synthetic phosphoric acid, natural phosphoric acid, polystyrene resin, polystyrene resin,
These include urea-pormarine resin.

It is appropriate that the pigment has an average particle size of 1 to 10 μm;
~6 μm is preferred.

Adhesives include water-soluble polymeric substances such as starch, starch derivatives, CMC, and polyvinyl alcohol and hydrophobic emulsions such as SBR.

Examples include MBR and acrylic resins, and any water-soluble resins and hydrophobic polymer substances similar to these can be used in the undercoat layer of the present invention.

The coating amount of the undercoat layer is 3g/rrf' to 20g/rd
Is it common?

As a method for forming the undercoat layer, any known coating method such as air knife, blade, gravure, roll coater, spray, tip, bar, extrusion, etc. can be used.

In the heat-sensitive recording material of the present invention, the support material is not particularly limited. For example, paper, synthetic fiber paper, synthetic resin film, etc. can be used as appropriate. Paper is generally preferred.

A thermosensitive color forming layer is formed on the undercoat layer.

There are no particular limitations on the colorless or light-colored basic leuco dye and coloring agent used to form the thermosensitive coloring layer.

For example, you can use:

As basic dyes, triallylmethane dyes such as 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophenyl, 3-diethylamino-6-methyl-
7-phenylaminofluorane, 3-dibutylamino-
6-methyl-7-phenylaminofluorane, 3-(
N-cyclohexyl-N-medylamino)-6-methyl-7-phenylaminofluorane, 3-dibdelamino-7-(0-chlorophenylamino)fluorane, 3-
(N-ethyl-N-isoamyl)amide, no-6-methyl-7-phenylaminofluorane, and the like.

Acidic 113 coloring agent -) liquefies due to temperature rise,
Any material that has the property of being soluble or soluble, and has the property of rapidly changing color upon contact with the basic dye may be used. Typical specific examples include 4-tart-butylphenol, 4-acetylphenol, 4-tOrt-ocdylphenol, 4.4'-5ee-butylidenediphenol, 4-phenylphenol, 4.4'-dihydroxy-diphenylmethane. , 4,4'-isopropylidene diphenol, hydroquinone, 4,4'-chlorohequinylidene diphenol, 4,4'-dichlorodiphenyl sulfide, 4,4'-thiobis(6-tert-butyl- 3-methylphenol), 4,4'-dihydroxydiphenylsulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone, 4-hydroxybenzophenone, dimethyl 4-hydroxyphthalate, methyl 4-hydroxybenzoate, 4-hydroquine Ethyl benzoate, propyl 4-hydroxybenzoate, 5ec-butyl 4-hydroxybenzoate, phenyl 4-hydroxybenzoate, benzyl 4-hydroxybenzoate, l-lyl 4-hydroxybenzoate, chlorophenyl 4-hydroxybenzoate , phenolic compounds such as 4,4'-dihydroxydiphenyl ether, benzoic acid, p -tert-
Butylbenzoic acid, trichlorobenzoic acid, terephthalic acid,
Salicylic acid, 3-isoprobylsalicylic acid, 3-te
rt-butylsalicylic acid, 3-penzylsalicylic acid, 3
- aromatic carboxylic acids such as (α-methylbenzyl)salicylic acid, 3,5-di-tert-butylsalicylic acid,
and organic acidic substances such as these phenolic compounds, salts of aromatic carboxylic acids and polyvalent metals such as zinc, magnesium, aluminum, and calcium.

In forming the heat-sensitive coloring layer, auxiliary substances that can be normally added can be used in combination. For example, as a sensitizer, parabenzylphenyl, dibenzyl terephthalate, phenyl 1-hydroxy-2-naphthoate, dibenzyl oxalate, di-O-thalolbenzyl adipate, 1,2-di(3-methylphenoxy)ethane,
Di-p-thalolbenzyl oxalate and the like can be used.

In preparing a coating solution for forming a heat-sensitive coloring layer, water is used as a dispersion medium, and the dye and coloring agent are dispersed using a grinder such as a ball mill, attritor, or sand grinder to form a coating solution. Such coating liquids contain binders such as starches, hydroxyethylcellulose, methylcellulose, carboxymethylcellulose, gelatin, casein, gum arabic, polyvinyl alcohol, styrene, maleic anhydride copolymer salts, styrene-butadiene copolymer emulsion, etc. 2 to 40% by weight of total solids, preferably 5%
~25% by weight is used. Various auxiliary agents may be added to the coating liquid as necessary. For example, dispersants such as sodium dioctyl sulfosuccinate, potassium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate, and fatty acid metal salts, as well as antifoaming agents, fluorescent dyes, and coloring dyes can all be added. In addition, to further whiten the heat-sensitive coloring layer, kaolin, clay, talc, calcium carbonate, fired clay, titanium oxide,
Inorganic pigments such as diatoms, finely particulate anhydrous limestone, etc. can also be added. Waxes such as dispersions or emulsions of stearic acid, polyethylene, carnauba wax, paraffin wax, calcium stearate, zinc stearate, ester wax, etc. can also be added as necessary.

In the heat-sensitive recording material of the present invention, the method of forming the heat-sensitive coloring layer is not particularly limited. A suitable coating device such as an air knife coater or a blade coater can be used in the method of coating the heat-sensitive coloring layer forming coating liquid on the support.

The heat-sensitive coloring layer generally has a dry weight of 2=12 g/rd.

Preferably, it is formed in a range of 3 to 8 g/rrf'.

This will be explained in detail below using examples.

[Examples] Unless otherwise specified, parts and percentages in the examples indicate heavy clear parts and weight percentages, respectively.

Example 1 Water 100
100 parts 10% polyvinyl alcohol (G L 05 manufactured by Nippon Gosei) 100 parts
2 parts of zirconyl ammonium carbonate to 5 parts
After dispersing with a homogenizer for a minute, the mixture was mixed with 50 parts of 10% polyvinyl alcohol (GH17 manufactured by F1 Honsei Co., Ltd.) to prepare an undercoat layer coating solution.

This undercoat layer coating liquid was applied to a high-quality paper of 50 g/rr'I' at a coating amount of 7 g/rd and dried.

-Dispersions A and B were prepared as coating solutions for a thermosensitive coloring layer.

■ Preparation of dispersion A 3-(N-ethyl-N-iso-amyl)-6-methyl-7-phenylaminofluorane 20 parts by weight 10% polyvinyl alcohol 10 parts by weight water
This composition was ground to an average particle size of 21 parts using a sand grinder.

■ Preparation of dispersion B 4. 10 parts by weight of 4'-isopropylidenediphenol 10 mff p-benzylbiphenyl 1 part polyvinyl alcohol 10% solution 10 parts by weight Water
70 parts by weight ■ Preparation of coloring layer Above A: 40 parts of liquid, 160 parts of liquid B, 40 parts of calcium carbonate pigment, 20 parts of 30% paraffin dispersion, and 180 parts of 10% polyvinyl alcohol aqueous solution were mixed and stirred, and the coating liquid and did.

After drying, apply the obtained coating liquid to Undercoat) and paper.
It was coated and dried so that k was 4.5 g/nf to obtain heat-sensitive recording paper.

Comparative Example 1 A thermosensitive recording paper was produced in the same manner as in Example 1, except that the zirconyl ammonium carbonate aqueous solution was omitted in preparing the undercoat surface coating solution.

Comparative Example 2 A thermosensitive recording paper was obtained in the same manner as in Example 1, except that an aqueous zirconium acid chloride solution was used instead of an aqueous zirconyl ammonium carbonate solution in preparing the undercoat surface coating solution.

Comparative Example 3 A thermosensitive recording paper was obtained in the same manner as in Example 1 except that a zirconyl nitrate aqueous solution was used instead of the zirconyl ammonium carbonate aqueous solution in preparing the undercoat surface coating solution.

Comparative Example 4 A thermosensitive recording paper was obtained in the same manner as in Example 1 except that a zirconyl acetate aqueous solution was used instead of the zirconyl ammonium carbonate aqueous solution in preparing the undercoat surface coating solution.

The recording sensitivity of thermal paper was measured and the dregs and sticks were evaluated for five types of examples and comparative examples. The results are shown in Table 1.

Recording sensitivity was measured using a commercially available thermal facsimile IJ modified for testing purposes. 1 line recording time 1 抛See,
Under the conditions of a scanning line density of 8 x 8 dots/mm, the pulse width was modulated and the applied energy per dot was 0.24 mj.
, 0.39 mj, and 64 lines were printed. The color density at that time was measured using the Macbeth Densitometer RD-914.
The recording sensitivity of thermal paper was measured as a value representative of the recording sensitivity of thermal paper.

The above test machine was used to test the adhesion of waste to the thermal head.
The applied energy per dot is 0.45 mj, and 1
00m was printed.

In the table, the ○ symbol indicates that the amount of debris adhering to the head is very small and has no effect on the image, the Δ symbol indicates that the debris is clearly observed, and the × symbol indicates that the amount of debris adhering to the head is extremely large. . Furthermore, in order to investigate the occurrence of sticking, 8
00 line was printed. In the table, the ○ mark indicates that no sticking occurred, the Δ mark indicates that a sticking sound was observed, and the X mark indicates that a loud sticking sound occurred and disturbances occurred in the image and the line spacing.

118- [Effects of the Invention] The present invention makes it possible to provide a heat-sensitive recording material with excellent high-speed printing suitability without deterioration of recording sensitivity, less clouding, and no sticking, without providing a protective layer. became.

Claims (1)

[Claims] 1. A heat-sensitive recording material comprising a heat-sensitive coloring layer formed on a support, the heat-sensitive recording paper comprising an undercoat layer containing zirconyl ammonium carbonate.