JPS58215396A - Manufacture of heat-sensitive recording sheet - Google Patents

Abstract

PURPOSE:To obtain a recording sheet having a highly smoothened surface and containing a volatile dye uniformly dispersed into the texture without volatilization in the atmosphere by a method in which a gas-impervious sheet is lapped on the coated surface of a sheet coated with a volatile dye and then they are subjected to a heat treatment. CONSTITUTION:A coating material, consisting of 1-20wt% an organic dye volatilizable from solid or liquid state at 100-200 deg.C, having a comparatively small molecular weight, 2-40wt% a natural or synthetic resin binder, preferably a crosslinkable resin capable of binding with each other at the time of transfer and heating, and 40-97wt% a solvent, is coated on a 2-60-micron thick heat-resistant sheet in an amount of 0.1-2g/m<2>, and then an aluminum foil, or sheet or aluminum deposited film is lapped on the coated surface of both surfaces of the heat-resistant sheet. Then, they are subjected to a heat treatment at 100-200 deg.C for preventing the volatilization of the volatile dye, and then the aluminum foil, etc., is peeled off to obtain a recording sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-sensitive recording sheet material capable of forming clear images with high resolution on photographic paper.

Conventionally, systems have been developed that reproduce images taken with a video camera or still images from a television, VTR, video disc, computer, etc. directly on photographic paper in full color. The color-forming material used in this system is either a pigment that vaporizes when heated and coated on a sheet material such as paper, or the conventional thermal transfer printing paper for woven fabrics is inappropriate for the purpose of this system, and it is not suitable for printing. Fine coloring unevenness occurs on the paper (such coloring unevenness was not a problem with conventional large-sized thermal transfer printing), making it difficult to reproduce precise images such as people and landscapes, and the resulting images are different from conventional printing. The quality was not as good as silver halide photography. The present inventor previously proposed a method of applying pressure heat treatment to a sheet material coated with a volatile dye using a calendar roll as a method to solve these drawbacks, and most of the problems were solved. Another problem arose in that some of the volatile dye was volatilized during the pressure heat treatment.

As a result of intensive research to solve these problems, the inventor of the present invention has discovered that the vaporizable dye can be removed by overlapping a heat-resistant sheet material such as an aluminum sheet on the coated surface of the vaporizable dye-coated sheet and heat-treating the coated sheet. Almost no volatilization occurs, the volatile dye and binder can be uniformly distributed in the base material, and unevenness on the sheet surface can be eliminated, and as a result, the drawbacks of the conventional technology can be fully solved. Based on this knowledge, the present invention was completed.

That is, the present invention applies a coating composition consisting of a heat-vaporizable dye, a binder, and a solvent to a heat-resistant sheet-like base material, and then applies a gas-impermeable sheet material to the coated surface of the obtained coated sheet material. This is a method for producing a heat-sensitive recording/human material, which is characterized by superimposing the material and subjecting it to heat treatment.

Next, to explain the present invention in detail, the heat-resistant sheet-like material used in the present invention may generally be paper, and a preferred configuration has a thickness of about 20 to 60 μm, and a The amount is approximately 15-30 g/m''.

By using such a relatively dense and thin sheet material, it exhibits sufficient thermal conductivity when heated with a fine thermal head, making it possible to perform good thermal recording.

The coating composition containing the volatile dye used in the present invention is
A liquid composition consisting of a volatile dye, a binder, a solvent, and other optional ingredients, which is applied to the surface of the above-mentioned substrate by any coating method.

The vaporizable dye used in the composition is an organic dye having a relatively small molecular weight (for example, about 200 to 400), and is included in large amounts in conventionally known vaporizable dyes or dispersible dyes. The vaporizable dye used in the present invention is about 10
vaporizes from solid or liquid at temperatures between 0 and 200'C;
It dyes hydrophobic resin materials such as polyester, polypropylene, acetate, etc., and structurally, the main dyes are azo, anthraquinone, methyl, quinophthalo, and nitrodiphenylamine.

Binders used in the coating composition of the present invention include:
Any of the natural or synthetic binder resins used in conventional offset inks, gravure inks, or paints can be used; It is preferable to use a binder that forms a three-dimensional network and does not melt and stick when heated by a thermal head when the transfer sheet of the present invention is used. Any known crosslinkable resin, crosslinking agent, etc. can be used.

The coating composition used in the present invention consists of the above-mentioned pigment, binder, and solvent, and the solvents include water, alcohol, aromatic, aliphatic, naphthenic, inoparaffinic, ester, and ketone. Various solvents can be used alone or as a mixture.

The essential components of the coating composition used in the present invention are as described above, but various conventionally known additives can be used as required.

Such a coating composition is manufactured by blending the above-mentioned components and carrying out a normal dispersion treatment. It is preferred that the ratio is about 12 to 40 hereditaries and the solvent is about 40 to 97 hereditaries.

The coating composition described above is applied to the substrate by:
7- Tar, air knife coater, roll coater,
curtain coater, bar coater, gravure coater,
Any method may be used, such as a flen coater, a spray coater, a liquid screen, or a rotary screen, and the preferred coating amount is approximately 0.1 to 2 g/m'' (however,
(as the amount of dye) and, if necessary, dried to obtain a dye-coated sheet material.

The sheet material thus obtained is sufficient for other purposes, such as thermal transfer printing of woven fabrics, but as mentioned above is insufficient for forming precise photographic images. In other words, microscopically, there are minute irregularities on the coated surface, and the presence of the dye is particulate and non-uniform, and most of the dye is present on the surface of the base material and is not uniformly impregnated into the base material. Not yet.

In the present invention, the above-mentioned transfer sheet material is heat-treated to improve surface irregularities and pigment non-uniformity, but mere heating causes the vaporizable color t to volatilize into the atmosphere and disturb the surroundings. Since this may contaminate the material or reduce the dye concentration, the covered surface or both sides of the sheet material should be overlaid with aluminum foil, aluminum sheet, aluminum evaporated film, etc., and heated at about 10Q to 200'C to volatilize the dye. prevent. Any heating means may be used for such heat treatment, but it is recommended to use a heating device that can perform pressure treatment at the same time, such as a stationary flat press machine, a rotary flat press machine, a calendar roll machine, etc. Pressure treatment is preferred. When applying pressure, the pressure is preferably such that the thickness of the transfer sheet used is slightly reduced, for example, a pressure of 20 to 200 K9/cA. The most preferred embodiment is the temperature at which the dye vaporizes, e.g.
This is a method of continuously pressurizing and heating with a calender roll having a heating temperature of ~250°C. The object of the present invention can be obtained by peeling off the heat-resistant sheet material such as aluminum foil after heat treatment, but in order to facilitate this peeling, a release agent is applied in advance to the surface of the aluminum foil etc. It is preferable.

The recording sheet material of the present invention obtained as described above is
The surface is very smooth, and when the base material is paper, the binder containing the volatile pigment is sufficiently impregnated into the structure of the paper by heating (and pressure) treatment. The distribution is uniform throughout. Therefore,
By overlaying the recording sheet of the present invention on separately prepared photographic paper, the original image can be accurately reproduced using a thermal head. In addition, when a thermally crosslinkable binding material is used as a binder in a composition applied to a transfer sheet, the above heat treatment simultaneously significantly improves the heat resistance of the binder layer, so that the recording paper can be used during image formation. It is very advantageous because it does not fuse to photographic paper.

Next, the present invention will be specifically explained with reference to Examples.

In addition, the words ``part'' or ``section'' in the text refer to weight.

Example 1 Kayaset Red B (Nippon Kayaku) 15 parts, cellulose acetate propionate 15 parts, precipitated barium sulfate 5 parts
1 part, 40 parts of toluene, and 25 parts of inopropanol were dispersed in a ball mill to obtain a volatile pigment composition. The composition was diluted with an appropriate amount of solvent (a 1:1 mixture of toluene and inozolobil alcohol), and 10 g was printed on thin paper with a basis weight of 2 (Jg/d, thickness of about 35 μm) using a gravure printing machine.
After coating and drying, it was sandwiched between two sheets of 20 μm thick aluminum foil and heat-treated under pressure at a speed of about 5 m/m with a calender roll machine heated to 200'C. The aluminum foil was peeled off to obtain a heat-sensitive recording material of the present invention.

Example 2 10 parts of PTB-67 (blue pigment, Mitsubishi Kasei), 8 parts of polyvinyl alcohol, 72,671 parts of methylol, 1 part of silica, 0.1 part of ammonium nitrate and 80 parts of water were mixed, and dispersed with an attritor. A vaporizable dye composition was obtained. The composition was coated with a roll coater to a basis weight of 30
g/mo, approximately 159 on water-resistant tissue paper approximately 40μ thick
/m2 and dried, and the same procedure as in Example 1 was carried out to obtain a sheet material for heat-sensitive recording of the present invention.

Example 3 5 parts of Kayaset Yellow AG (Nippon Kayaku), 3 parts of carboxymethyl cellulose, 4 parts of polyvinyl alcohol, 0.1 part of an antifoaming agent, and 88 parts of water were blended, and this was dispersed in a ball mill. 1 part of methylolmelamine and 0.2 part of ammonium chloride were added to obtain a volatile dye composition. Using this composition, a sheet material for heat-sensitive recording of the present invention was obtained in the same manner as in Example 1.

Example 4 Kayaset Blue 906 (Nippon Kayaku) 10 parts, Evokin resin 20 parts, toluene 30 parts, soacetone alcohol 3 parts
A sheet material for heat-sensitive recording of the present invention was obtained in the same manner as in Example 1 except that 8 parts of silica, 2 parts of silica, 5 parts of methylolmelamine, and 72 parts of zoethylene triamine were used.

Comparative Examples 1 to 4 Comparative heat-sensitive recording sheet materials 1' to 4' were obtained in the same manner as in Examples 1 to 4, except that aluminum foil was not used in Examples 1 to 4. .

Usage Example 2 - Photographic paper coated with 109/- polyester resin on one side of the paper, Examples 1 to 4 and Comparative Examples 1 to 4
The heat-sensitive recording sheets obtained in step 1 were stacked, and a thermal head heated to 350°C was heated at a pressure of IK9/cm for 10 minutes.
The transfer color density of the dye was checked by pressing for milliseconds, and the results were as shown in Table 1 below.

Table 1 Heat-sensitive recording sheet Color density Example 11 1 1 1 Comparative example 1057 2 07 30.8 40.8 The color density of the example was 1, and the color density of the comparative example was visually compared.

Patent applicant Noney Co., Ltd. Same as Dainichiseika Kagyo Co., Ltd. Agent: Patent Attorney Souo Suga

Claims (3)

[Claims] (1) A coating composition consisting of a heat-vaporizable dye, a binder, and a solvent is applied to a heat-resistant sheet-like base material, and then a gas-impermeable sheet material is superimposed on the coated surface of the obtained coating sheet material. 1. A method for producing a heat-sensitive recording sheet material, the method comprising heat-treating the material. (2) Claim No. (1) in which heating is performed under pressure
The method described in section. (3) The method according to claim f11, wherein the binder is a heat-crosslinkable resin material.