JPS62278082A - Coated sheet - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention The present invention relates to a coated sheet. This coated sheet is useful in various fields, and is particularly useful as a synthetic paper or plastic sheet with improved suitability for printing and printers. For example, when used in thermal transfer printers, inkjet printers, printing machines, etc., it retains ink sharply, has good halftone reproduction, clearly accepts monochrome or multicolor ink, and prints and prints characters and images with high resolution. Used on synthetic paper or plastic sheets that can be printed.

[Conventional technology] Recently, the need for color printing and color printers has increased, and heat-fusing transfer printers using thermal heads and sublimation printers are attracting attention because they can produce clear color images. .

These melt-type thermal transfer printers can print film,
An ink sheet consisting of a base material such as thin paper and a heat-melting ink layer is used. A receiving paper such as plain paper, such as normal high-quality paper, is superimposed on this ink sheet, and heat from a thermal head corresponding to an image signal transfers the heat-melting ink to the receiving paper only in the necessary portions, thereby forming an image. In the case of a color printer, images of different colors such as yellow, magenta, cyan, and black are transferred and layered to create a color image. Since a pigment can be used as the main component of the colorant in the ink, it is possible to preserve the print permanently.

However, with such thermal transfer printers, the sharpness of the transferred image is affected by the smoothness of the receiving paper, so even though it is a plain paper recording method, it is not possible to print images of the same high quality on any type of paper. Do not mean. Various techniques have been published for imparting image-receiving suitability to receiving paper depending on the use of each printer.

In such a thermal transfer method, it has become possible to print halftone full color images using an area gradation method. Even with such area gradation method thermal transfer printer paper, in order to obtain good printing, the high-quality paper is smoothed using a super calendar, etc., and the Beck smoothness of normal high-quality paper is about 10 to 50 seconds. , 100 seconds or more, it is known that the clarity of the transferred image is improved.

However, in addition, it is necessary to obtain uniform hues and densities of monochromatic yellow, cyan, and magenta, that is, red, blue, and green, and to obtain high-resolution characters and images with good reproducibility. Even if the time is 100 seconds or more, it is difficult to do so with high-quality paper. 16 more dots/
(2) A high resolution of 32 dots/11 m has begun to be required for thermal transfer printers, and the limits of uncoated paper with exposed cellulose fibers on the surface have become apparent. For example, in order to improve the transfer characteristics of a thermal transfer printer, a proposal has been made (Japanese Patent Application Laid-Open No. 182487/1987) to provide an oil-absorbing pigment on a paper base material to obtain a transferred image with uniform shading. Most of the pigments used in coated printing papers are listed, and some improvement in thermal transfer receptivity has been obtained.

However, in printers that control the amount of molten ink transferred from a thermal head, the uniformity of the ink receiving ability of the receiving paper has a significant impact on image reproducibility, and conventional coating Even when uncoated thermal transfer receiving paper was used, uneven density in solid areas and unstable transfer of halftone dots were observed, and good halftone images could not be obtained.

[Problems to be Solved by the Invention] A particular object of the present invention is to provide a new coated sheet useful as a thermal transfer receiving sheet used in a thermal transfer printer whose purpose is to obtain full-color images. Another object of the present invention is to provide a coated sheet that can be used in image forming systems that require higher resolution and higher fidelity. Furthermore, to provide a coated sheet suitable for a thermal transfer receiving sheet for a full-color printer, in which the halftone density of halftone dots and solid areas is evenly reproduced, and a clear recorded image can be stably obtained from low density to high density. The purpose is to

[Means for Solving the Problem] As a result of intensive research to improve the above-mentioned drawbacks, the present inventors have developed a biaxially stretched thermoplastic polymer film with a multi-layered structure mainly composed of polyolefin containing an inorganic pigment. Oil absorption amount on at least one side of the sheet base material is 60ml/100t
We have developed a sheet with a lipophilic coating layer at a ratio of 5 to 50 fI/j2 to improve receptivity, which is mainly composed of a pigment of i or higher and an adhesive, and this sheet absorbs and adheres thermal transfer ink. By allowing the image to be accepted by the image forming method, it is possible to improve the reliability and density reproducibility of halftone dots and the reproducibility of hue and density of overlapping colors in solid areas in image forming methods that reproduce halftone images using the area gradation method. It has been found that it is possible to realize uniform reproducibility of hue and density of full-color recorded images.

That is, in the present invention, a coating layer is provided on the surface of a support made of synthetic paper having a multilayer structure.

The support has a paper-like layer made of a thermoplastic resin film containing 8 to 65% by weight of inorganic fine powder, and in addition to the paper-like layer, a base material layer or preferably a thermoplastic resin film containing 0 to 3% by weight of inorganic fine powder. It can include a surface made of a resin film.

Examples of thermoplastic resins constituting each layer of the support include polyolefin resins such as polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, poly(4-methylpentene-1), polystyrene, polyamide, and polyethylene terephthalate. , partial hydrolyzate of ethylene-vinyl acetate copolymer, ethylene-
Among these, polyolefin resins such as polyethylene and polypropylene are preferred, including acrylic acid copolymers and their salts, vinylidene chloride copolymers such as vinyl chloride-vinylidene chloride copolymers, and mixtures thereof.

The inorganic fine powder that should be blended into the thermoplastic drilling resin is as follows:
Calcium carbonate, calcined clay, diatomaceous earth, talc, titanium oxide, barium sulfate, aluminum sulfate, silica, etc. with an average particle size of 20 μm or less are used for the base layer and paper-like shoes, and for the back layer. , calcium carbonate, titanium oxide, barium sulfate, etc.

In the past, attempts have been made to use pigments as part of paints to improve oil absorption and general printability, but
It has not been previously known that multilayer structured films can be used to improve uniform and gradation image reproducibility of thermally transferred images.

In the present invention, a lipophilic pigment with an oil absorption of 60R1/100g or more is used. Oil absorption amount 60zl/], OOy
The reason for using the above pigments is to improve the adsorption of transfer ink in a molten state. Oil absorption amount 60zl/1
If less than 0.00 g of pigment is used, adsorption is insufficient and a desired clear recorded image cannot be obtained.

Lipophilic oil absorption used in the present invention: 60yil/100g
As the pigment, calcined clay, finely powdered silica, etc. are particularly preferred. However, if necessary, the oil absorption capacity is usually 40a.
+1/100g or less of kaolin and various clays, calcium carbonate, titanium dioxide, aluminum hydroxide, satin white, talc, calcium sulfite, etc. can be mixed up to about 50% by weight.

As for the adhesive used as the surface layer component, those whose main component is an acrylic polymer or copolymer emulsion are best in terms of image reproducibility. However, styrene-butadiene, methyl methacrylate-styrene
Butadiene type and vinyl acetate type can be used.

Furthermore, water-soluble polymer adhesives such as polyvianyl alcohol, starch, and casein can also be used. The coating layer may also be formed by solvent coating using an adhesive soluble in a non-aqueous solvent such as toluene.

The lipophilic coating layer must be provided at a ratio of 5 to 30 fI/x2.* If it is less than 5 g/z2, the desired effect cannot be obtained, and if it is more than 50 g/i+2, the strength of the coating layer is insufficient. Phenomena such as bending and cracking easily occur, so it is not suitable.

By forming the surface layer in this manner, the sheet of the present invention exhibited a high degree of image reproducibility never seen before.

As the sheet base material, general high-quality paper or a sheet made of thermoplastic polymer material can be used.

In particular, a biaxially stretched polyolefin sheet containing an inorganic pigment is known as synthetic paper and is preferred.

This synthetic paper is produced from opaque paper to translucent trace paper depending on the amount and type of pigment added, and can also be used as a spacer for converting thermoplastic film into paper, or as a surface printing paper. Although suitable inorganic pigments are selected and used in order to impart writing suitability, any of them can be used.

The thickness of the sheet may be appropriately selected depending on the use as a thermal transfer receiving sheet. The size is usually 60 to 200 μm.

The thermal transfer method is the mainstream of small non-impact printers, and is often used for kanji printers and small color printers, and there is a need for a system and paper that can produce clear images with halftone reproduction using the thermal transfer method. has been done. By realizing paper with high resolution and color reproducibility according to the present invention, it becomes possible to make hard copies of full-color images such as video screens with a compact device, and a variety of applications become possible.

This sheet is also useful for various image forming methods other than thermal transfer receiving sheets because of its surface lipophilicity and uniform receptivity.

[Example] Next, the present invention will be explained by examples.

Example 1 A biaxially oriented polyolefin film containing an inorganic pigment (YUBO FPG60 manufactured by Tamago Yuka Synthetic Paper) was used as a base material, and the following paint-1 was applied at a rate of 30 g/w2, and the coating was treated with a super calender. The surface was smoothed to obtain a coated sheet.

Paint-1 Baked Sea (Ansilex, Engelhall, USA) - Oil absorption 11
0wl/100g clay) 100 parts Carboxyl-modified styrene-butadiene copolymer latex (JSR-0668 Japan Synthetic Rubber) 20 parts Sodium polyacrylate dispersant 2 parts The obtained sheet was coated with Bekk smoothness (Oken type) The smoothness of the opposite surface was 550 seconds.

Example 2 Using a polyester film (thickness: 60 parts) as a base material, the following paint-2 was applied at a rate of 20 g/x'',
The surface was smoothed by supercalender treatment in the same manner as in Example-1 to obtain a coated sheet.

Paint-2 Particulate silica (Tokuyama Soda Tokusil GUN oil absorption 2
00wl/100y silica) 100 parts Carboxyl-modified styrene-butadiene copolymer latex (JSR-0668 Japan Synthetic Rubber) 20 parts Sodium polyacrylate dispersant 2 parts The resulting sheet has a coated surface smoothness (Oken type) of 12,000 seconds. , the smoothness of the opposite surface was 550 seconds.

Example 3 Using high-quality paper (OK F 55 kg>) as a base material, the following paint 3 was applied at a rate of 35 g/m'', and the surface was smoothed by supercalender treatment to obtain a coated sheet.

Paint-3 Calcined kaolin (same as Example-1) 100 parts = 1
1- Vinyl acetate copolymer emulsion (Kanebo N.C. 225-5099) 20
1 part Sodium polyacrylate dispersant 2 parts The produced sheet had a Bekk smoothness (Oken type) of 8500 seconds on the coated surface and a smoothness of 400 seconds on the opposite surface.

Comparative Example 1 Using the biaxially stretched polyolefin film used in Example-1 as a base material, the following paint-4 was applied at 35g/i+2
The coated sheet was coated and the surface was smoothed by super calender treatment to obtain a coated sheet.

Paint-4 Clay (U.S. Engelhardt Co., Ltd. HT Crecy oil amount 3
9wl/100g) 100 parts vinyl acetate copolymer emulsion (Kanebo N.N.C. 225-5099>20
Part Sodium Polyacrylate Dispersant Part 2 The produced sheet had a Bekk smoothness (Oken type) of the coated surface of 4000 seconds and a back surface smoothness of 250 seconds.

Comparative Example 2 The polyolefin film used in Example-1 as a base material was evaluated as a sheet. The Bekk smoothness of the surface (Ouken method) was 260 seconds, and the smoothness of the back was 250 seconds.

Evaluation 1) Thermal transfer printer Yellow, magenta, cyan 3 with a 6μ-thick polyester base material and a Waraku pigment ink layer on top of it.
The ink sheets of each color were heated in stages using a commercially available thermal head to thermally transfer the images onto the sheets, thereby printing single-color and overlapping color images of each color. The image on this receiving sheet was visually evaluated for image clarity, dot uniformity, and solid area uniformity.

The results are shown in the table below. Particularly excellent evaluation results were marked as ◎, good as 0, those with some defects as △, and those with significant defects as ×.

Table [Effects of the Invention-1 The present invention provides a coated sheet that is excellent in terms of color clarity, gradation, low density, and uniformity of common density, and solves the drawbacks of conventional methods. This enables compact full-color thermal transfer printers and hard copies.

Procedural amendment August lq day, 1986

Claims (1)

[Scope of Claims] 1. Consisting of an axially stretched multilayered thermoplastic polymer material film mainly composed of polyolefin containing an inorganic pigment, the film has an oil absorption of 60 ml/10 on at least one side of the sheet base material.
A sheet comprising a lipophilic coating layer containing 0 g or more of pigment and an adhesive at a ratio of 5 to 50 g/m^2. 2. The sheet according to claim 1, wherein the main pigment component of the lipophilic coating layer is calcined clay. 3. The sheet according to claim 1, wherein the main component of the adhesive in the lipophilic coating layer is an acrylic copolymer.