JPS6328693A - Receiving sheet for thermal transfer printer - Google Patents

Abstract

PURPOSE:To improve the clearness and the gradation of coloring, by applying a lipophilic coating layer mainly composed of ethylene-vinyl chloride series copolymer by 2-50g/m<2> onto at least one face of sheet base material composed of a thermoplastic macromolecular material. CONSTITUTION:A lipophilic coating layer mainly composed of ethylene-vinyl chloride copolymer is applied by 2-50g/m<2> onto at least one face of a sheet base material composed of a thermoplastic macromolecular material so as to form a receiving sheet for a thermal transfer printer. Preferably, the lipophilic coating layer contains a plastic pigment mainly composed of styrene as a pigment component, and a acrylic acid ester series copolymer as an adhesive component. Preferably, the sheet base material is mainly composed of poly olefin containing inorganic micro pigment and biaxially stretched into a film of double layer structure.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a synthetic paper or plastic sheet with improved suitability for printing and printers, and when used in thermal transfer printers, inkjet printers, printing machines, etc. Synthetic paper and sheets that retain sharpness, have good midtone reproducibility (clearly accept monochrome or multicolor ink, and can print characters and images with high resolution) It is something.

[Conventional technology]

Recently, the need for color printing and color printers has increased, and in particular, heat-melting transfer printers using thermal heads and dye sublimation transfer printers are attracting attention because of their ability to produce clear color images. There is.

Among these, printers using the melt transfer method use an ink notebook consisting of a base material such as a film or thin paper, and a heat bath/ink layer. For example, is this ink notebook made of normal high-quality paper? By adjusting γ according to the image signal,
The heat from the thermal head transfers the hot bath melting ink onto the receiving paper only in the necessary areas, forming an image. In the case of a color printer, images of different colors such as yellow, magenta, cyan, and black are transferred and superimposed to create a color image.

Pigment 2 can be used as the main component of the layer colorant in the ink, making it possible to permanently preserve printed images.

However, in such thermal melt transfer printers, the sharpness of the transferred image depends on the smoothness of the receiving paper, etc., and it is not possible to print images of the same high quality on all types of paper. Various techniques have been published for imparting gamma grains to receptive papers, depending on the printer's suitability for image receptivity.

In such a thermal transfer method, it is possible to print halftone full-color images based on the area gradation method.

In order to obtain a good transferred image, the receiving paper for this area gradation type thermal transfer printer has a Bekk smoothness of 10 to 5.
It is known that if the smoothing ratio is processed for about 0 seconds using ordinary high-quality paper, super calender, etc., and the time is longer than 100 seconds, the sharpness of the transferred image will change.

However, 16 dots/tomo~32 dots 71111
High-resolution thermal transfer printers have been developed, and a method for controlling the size of transfer dots with an accuracy of 10 μm or less has been announced, making the requirements for N image resolution even more severe. The limitations of uncoated paper, in which cellulose memory fibers are exposed on the surface, are obvious. Furthermore, what is the uniformity of the hue and density of the single colors yellow, cyan, and magenta that are printed in multiple colors, namely red, blue, and green? It is difficult to obtain an image with good reproducibility based on overlapping dots even when using high-quality paper or coated paper with a Bekk smoothness of 100 seconds or more. For example, in order to improve the transfer quality of thermal transfer printers, a proposal was made to obtain transferred images with even shading by providing oil-absorbing pigments on the paper base material (Japanese Patent Laid-Open No. 57-182487
) has been done. Most of the pigments used in coated printing papers are listed below, and some improvement in thermal transfer receptivity has been obtained.

However, in area gradation type printers that control the transfer area of the bath-melting interface from the thermal head, the uniformity of the ink-receiving ability of the receiving sheet has a significant impact on the reproducibility of overlapping color images2. Even when using conventional coated and uncoated thermal transfer receptor paper, uneven density in solid areas, unstable transfer of halftone dots, etc. are observed, and uniform and good halftone images cannot be obtained. 1 child.

[Problem that the invention seeks to solve]

It is an object of the present inventor to provide a new coated sheet useful as a thermal transfer receiving sheet for use in thermal transfer printers for obtaining full-color images. The aim is also to provide a coated sheet that can be used in image forming methods.Furthermore, the halftone density due to the area gradation of the peta area and halftone dots is unevenly reproduced (reproduced stably and clearly from low density to high density). The purpose of the present invention is to provide a coating sheet that can be used in a thermal transfer receiving channel for a full-color printer, and which can obtain a recorded image.

[First Means to Solve the Problems] As a result of extensive research, the present inventors have found that the sheet base material of a thermoplastic polymer film, preferably a biaxially oriented polyolefin film containing an inorganic pigment, can be reduced in size. (Ethylene-vinyl chloride copolymer, which does not necessarily have good adhesion.) Image formation that reproduces halftone images with area gradation by providing a lipophilic coating layer on one side to improve receptivity. We have devised a method that can achieve reliable transfer of halftone dots and uniform density reproducibility in this method.

The present invention relates to such a receiving sheet for thermal transfer printers.

The ethylene-salt 1-hibinyl copolymer used in the present invention has neither the function of a pigment used in ordinary coated paper nor the function of adhesion to pigments. It is thought that it mainly works as an adhesion improving agent for transfer inks.

For this reason, it is essential to supply a supplement. It is also desirable to include some kind of pigment 2 in order to improve the uniformity of transfer and the gradation of images. The reason why this ethylene-salt vinyl copolymer significantly improves the transfer receptivity of thermoplastic polymer base sheets is not completely clear, but wax and petroleum resin, which are the main components of transfer ink, are not completely clear. ,ethylene·
It is estimated that it is a gamma paste that has stable adhesion to vinyl acetate resin, etc. without blocking. The ethylene-salted vinyl copolymer is preferably one containing ethylene, vinyl acetate, vinyl acetate, etc. as a comonomer. For example, 0 to 40% by weight of vinyl acetate, 10 to 50% by weight of ethylene, and 60 to 85% by weight of vinyl salt are examples of copolymers that can be expected to be effective.

The ethylene-salted vinyl copolymer (preferably vinyl acetate-ethylene-41tS vinyl copolymer) used in the present invention is usually produced by emulsion polymerization and blended and used as a single emulsion.

The lipophilic pigment used in the present invention is preferably a plastic pigment containing styrene as a main component, and if necessary, other pigments such as inorganic pigments may be added. If only the focal range pigment is used alone, it will lack uniform oil absorption on the μm order, or it will become non-uniform and the desired clear recorded image will not be obtained.

Inorganic pigments include silica, various clays such as fired clay, calcium carbonate, and diacid titanium.

Aluminum hydroxide, satin white, Merck, calcium sulfite, and other combinations can be used.

The adhesive used as a coating layer component is acrylic.
Those whose main component is an ester polymer or copolymer emulsion are the best in terms of uniform image reproducibility.

However, styrene-butadiene-based, methyl methacrylate-styrene-butadiene-based, vinyl acetate-based polymers,
It is possible to use water-soluble polymer adhesives such as copolymers, polyvinyl alcohol, starch, and casein alone or in combination.

The lipophilic coating layer is preferably provided at a ratio of 2 to 50 g/m'. If it is less than 2 fi/m, the desired effect cannot be obtained, and if it is more than 50.9/m', the strength of the coating layer is insufficient and problems such as bending cracks and cracks may occur, which is not appropriate.

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

The present invention provides a coating layer on the surface of a thermoplastic polymer film sheet substrate, preferably synthetic paper having a multilayer structure. The support having a multilayer structure is preferably composed of a paper-like layer and a base material layer of a thermoplastic film containing 78 to 65% by weight of fine inorganic powder, and 0 to 6% by weight of fine inorganic powder. It can also have a surface layer consisting of a thermoplastic film.

Biaxially oriented polyolefin sheets containing these inorganic pigments are known as synthetic papers, and depending on the amount of the two pigments added, opaque papers and translucent trace papers are produced.

As the thermoplastic resin constituting each layer, polyolefin resins such as polypropylene and polyethylene are preferred, but polystyrene, polyethylene terephthalate, etc., and mixtures thereof may also be used. I can give an example.

As a spacer for thermoplastic film paper,
In addition, as the inorganic fine powder that is added to the film to give the surface printing and writing properties, for the second paper-like base layer, calcium carbonate with an average particle size of 20 μm or less, calcined clay, silica gravel, Merck.

Examples include acid-based titanium, silica, etc., and calcium carbonate, carbon-based titanium, etc. for the surface layer.

The thermal transfer method is expected to be increasingly used in color printers as the mainstream of small non-impact printers, and there is a demand for systems and paper that can produce clear images with halftone reproduction. The present invention has realized a high-resolution, full-color reproducibility receiving sheet, which enables Victorian color I[! li
It is expected that hard copying of images will become possible with a compact device, opening up a wide variety of applications.

〔Example〕

Next, the present invention will be explained in detail with reference to examples.

In the following, parts indicate parts by weight of solid content.

Example 1 A biaxially oriented polyone film containing an inorganic pigment χ (manufactured by Yupo FPG60 Oji Yuka Synthetic Paper) was used as a base material, and the following paint-1 was applied at a rate of 60 g/m2, followed by super calendering. The surface was smoothed to obtain a receiving sheet.

Paint-1 Sodium polyacrylate dispersant 2 parts The produced sheet has a violet surface Bekk smoothness (Oken type) of 4
The smoothness of the opposite surface was 550 seconds.

Example 2 A polyester film (thickness: 60 μm) was used as a base material, and the following paint was coated at a ratio of 209/m', and the surface was smoothed by supercalendering to obtain a receiving sheet.

Paint-2 Sodium polyacrylate dispersant 2 parts The produced sheet has a Bekk smoothness (Oken type) of the coated surface of 1.
The smoothness of the opposite surface was 550 seconds.

Example 6 Using the same sheet 'Y as in Example-1 as the base material, paint-
6 was coated at a rate of 1 U/m2, and the narrow surface was smoothed by supercalendering to obtain a receiving sheet.

Falling fee-6 The generated gamma sheet has a Bekk smoothness of the coated surface (Ouken type) 1
5000 seconds, and the smoothness of the opposite side was 550 seconds.

Comparative Example 1 The biaxially oriented polyolefin film used in Example-1 was used as a base material, and the following coating was applied to A-4 at 559/m, and the surface was smoothed by supercalendering. I got 7.

Fallen-4 The generated sheet has a Bekk smoothness (Oken type) of the coated surface of 40
00 seconds, and the smoothness of the back surface was 250 seconds.

Comparative Example 2 The polyolefin film χ used in Example 1 as a base material was evaluated as a sheet without being coated. The Bekk smoothness (Ouken method) of the surface was 620 seconds, and the smoothness of the back was 550 seconds.

Comparative Example A high-quality paper (64 g/m) Y was used as a filter substrate, and the following paint 5 was coated at ysg/m, and the surface was smoothed by supercalender treatment to obtain 2 receiving sheets and 1 receiving sheet.

Paint-5 Sodium polyacrylate dispersant 2 parts The produced sheet has a coated surface Bekk smoothness (Oken type) of 40
00 seconds, and the smoothness of the back surface was 250 seconds.

Evaluation The receptor sheets obtained in each of the above Examples and Comparative Examples were evaluated in the following manner.

1) Thermal transfer printer Yellow, with a 6 μm thick polyester base material and a wax-pigment ink layer on top.

Ink sheets for each of the 6 colors of magenta and cyan? The images were heated in stages using a commercially available thermal head and thermally transferred to the sheet, thereby printing monochromatic and overlapping images of each color. The image on this receiving sheet was visually evaluated for image clarity, dot uniformity, transfer certainty, and color overlapping uniformity.

The results are shown in the table below. Those with particularly excellent evaluation results are indicated as ◎, good quality, and those with some defects are indicated as Δ, and those with significant defects are indicated as ×.

Table [Effects of the Invention] The receiving sheet for thermal transfer printers of the present invention has excellent color clarity, gradation, low color density, and density uniformity, and has no drawbacks to the method of using rice. Y:N6 is a compact, full-color thermal transfer printer that enables hard copy printing.

Claims (1)

[Claims] 1. A lipophilic coating layer containing an ethylene-vinyl chloride copolymer as a main component is applied on at least one side of a sheet base material made of a thermoplastic polymer material at a rate of 2 to 50 g/m^2. A receiving sheet for a thermal transfer printer, characterized in that it is provided in a proportion. 2. The receiving sheet according to claim 1, wherein the lipophilic coating layer contains a plastic pigment made of a polymer mainly composed of styrene as a pigment component. 3. The receiving sheet according to claim 1, wherein the lipophilic coating layer contains an acrylic-ester copolymer as an adhesive component. 4. The receiving sheet according to claim 1, wherein the sheet base material made of a thermoplastic polymeric material is a biaxially stretched film having a biaxially stretched polyolefin containing a fine inorganic pigment.