JPH03268998A - Thermal transfer image receiving sheet - Google Patents

Abstract

PURPOSE:To form an image generating no density irregularity or missing dots in the formation of a color image and having high density and high resolving power without generating curl by constituting a base sheet by laminating a foamed polyolefin layer to both surfaces of a core material. CONSTITUTION:Paper of every kind is used as a core material and a foamed polyolefin layer having a thickness of 30-80mum is laminated to both surfaces of the core material. The foamed polyolefin layers composed of the same mate rial are pref. laminated to both surfaces of the core material in the same thick ness but a different kind of the foamed polyolefin layers may be laminated to both surfaces of the core material in different thcknesses. The total thickness of the three-layer laminate (base sheet) is set to 100-300mum.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a thermal transfer image-receiving sheet that is free from curls, uneven density, dots, etc. (a thermal transfer image-receiving sheet capable of forming high density and high resolution images). The purpose is to provide sheets.

(Prior art and its problems) Conventionally, various thermal transfer methods are known, but among them, a thermal transfer sheet is produced by using a sublimable dye as a recording agent and supporting it on a base sheet such as paper or a plastic sheet. There have been proposed methods for forming various full-color images on a thermal transfer image-receiving sheet that can be dyed with a sublimable dye, such as a thermal transfer image-receiving sheet in which a dye-receiving layer is provided on the surface of paper or plastic film.

In this case, the printer's thermal head is used as a heating means, and by heating in an extremely short time, three or four colors can be printed.
A large number of colored dots are transferred to a thermal transfer image-receiving sheet, and a full-color image of an original is reproduced using the multicolored colored dots.

The images formed in this way are very clear because the coloring material used is dye, and they have excellent transparency, so the images obtained have excellent intermediate color reproducibility and gradation, and are It is possible to form high-quality images that are similar to images produced by offset printing or gravure printing, and comparable to full-color photographic images.

Thermal transfer image-receiving sheets used in the dye-sublimation thermal transfer method described above are required to have color development and density that accurately corresponds to thermal dot printing, so that images with high density and resolution can be obtained without uneven density or missing dots. However, if the image receiving sheet is hard and lacks cushioning, the thermal head
The total thickness of the thermal transfer sheet and the image-receiving sheet is no longer uniform, and the printing pressure of the thermal head becomes non-uniform, resulting in problems such as missing dots and uneven density in the print.

As a method for solving such problems, a method is known in which a cushion layer is formed on either side of a base sheet such as a piece of paper, and a method has been proposed in which a foamed resin sheet is used as the cushion material.

In the case of an image-receiving sheet having a cushion layer as described above, there is not much of a problem when printing in a single color, but when printing three or four colors such as yellow, magenta, cyan, and even black to form a full-color image. In this case, missing dots occur especially in the highlighted areas (light colored areas).
In the shadow part (dark color part), surface irregularities of the paper that is the base sheet appear, causing density unevenness, and at the same time, there is a problem that severe curling of the image receiving sheet occurs during printing.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, and to form a thermal transfer image-receiving sheet that is capable of forming high-density and high-resolution images without curling and without density unevenness or missing dots even in full-color image formation. The goal is to provide the following.

(Means for solving problems) The above objects are achieved by the present invention as described below.

That is, the present invention provides a thermal transfer image-receiving sheet comprising a base sheet and a dye-receiving layer formed on the surface thereof, wherein the base sheet has a structure in which foamed polyolefin layers are laminated on both sides of a core material. be.

(Function) When a full-color image is formed on a conventional thermal transfer image-receiving sheet, thermal printing is performed three to four times in the same area, and as a result, the cushion layer is soaked by the printing pressure, and in dark-colored areas, the paper is Surface irregularities of the core material appear, resulting in uneven density, and in light-colored areas, missing dots occur due to uneven printing pressure. After printing three or four more times, only one side of the image-receiving sheet was heated with a large amount of heat, resulting in severe curling.

In the present invention, by laminating foam layers on both sides of a core material such as paper, the cushioning properties of the cushion layer are improved, preventing curling during printing, and eliminating density unevenness and missing dots even in full-color image formation. It becomes possible to form images with high density and high resolution.

(Preferred Embodiments) Next, the present invention will be described in more detail by citing preferred embodiments.

In the thermal transfer image-receiving sheet of the present invention, as its cross section is schematically shown in FIG.
A dye receiving layer 3 is formed on both sides.

The core material used in the present invention may be various plastic films or sheets, but in consideration of cost and stiffness, various types of paper such as high-quality paper, art paper, coated paper, cast coated paper, etc. Papers such as wallpaper, lined paper, paper impregnated with synthetic resin or emulsion, paper impregnated with synthetic rubber latex, paper with internal addition of synthetic resin, paperboard, etc. are suitable, and the thickness of these core materials is arbitrary, but - for boat fishing. The thickness is approximately 30 to 200 μm.

As the foamed polyolefin to be laminated on both sides of the core material, foamed polypropylene, foamed polyethylene, foamed polystyrene, etc. are used, and foamed polypropylene is particularly preferred in consideration of various strengths, cushioning properties, etc.

The thickness of the foamed polyolefin is also important, and the preferred thickness is 30 μm to 80 μm. If the thickness is 30 μm without drops, the foam layer will be severely soaked after printing 3 to 4 times.
Problems such as density unevenness, spotting and curling occur, and on the other hand, if it exceeds 80 um, it is unfavorable in terms of cost, weight, transportability, etc. It is preferable that polyolefin foams made of the same material and having the same thickness be laminated on both sides of the core material, but polyolefins of different types and thicknesses may be laminated on both sides.

The total thickness of the three-layer laminate is also important, and the preferred total thickness is in the range of 100 to 300 μm. Even if it is thinner or thicker than this, it will not affect stiffness, curl, weight, cost, transportability, etc. So it's not desirable.

When the base sheet as described above has poor adhesion to the dye-receiving layer formed on the surface thereof, it is preferable to subject the surface thereof to a primer treatment or a corona discharge treatment.

The dye-receiving layer formed on the surface of the base sheet is for receiving the sublimable dye transferred from the thermal transfer sheet and maintaining the formed image.

Examples of the binder resin for forming the dye-receiving layer include polyolefin resins such as polypropylene, halogenated vinyl resins such as polyvinyl chloride and polyvinylidene chloride, vinyl resins such as polyvinyl acetate and polyacrylic ester, Polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polystyrene resins, polyamide resins, copolymer resins of olefins such as ethylene and propylene and other vinyl monomers, ionomers, cellulose resins such as cellulose diacetate, polycarbonates Among them, vinyl resins and polyester resins are particularly preferred.

The dye-receiving layer in the thermal transfer image-receiving sheet of the present invention is prepared by adding necessary additives such as an antioxidant and an ultraviolet absorber to the binder resin as described above on at least one side of the base sheet. A dispersion obtained by dissolving in a suitable organic solvent or dispersing in a Ti solvent or water is coated and dried by a forming method such as a gravure printing method, a screen printing method, or a reverse roll coating method using a gravure plate. and form it.

The dye-receiving layer preferably contains a release agent in order to provide good release properties from the thermal transfer sheet. Preferred mold release agents include silicone oil, phosphate ester surfactants, fluorine surfactants, and silicone oil is preferred. As the silicone oil mentioned above, modified silicone oils such as epoxy-modified, alkyl-modified, amino-modified, carboxyl-modified, alcohol-modified, fluorine-modified, alkylaralkyl polyether-modified, epoxy-polyether-modified, and polyether-modified silicone oils are desirable.

One or more types of mold release agents may be used. The amount of the release agent added is preferably 1 to 20 parts by weight per 100 parts by weight of the binder resin. If the amount added does not fall within this range, problems such as compatibility between the thermal transfer sheet and the dye-receiving layer or a decrease in printing sensitivity may occur.

The dye-receiving layer formed as described above may have any thickness, but the thickness for boat fishing is 1 to 50 μm. Although such a dye-receiving layer is preferably a continuous coating, it may also be formed as a discontinuous coating using a resin emulsion or resin dispersion.

In addition, in order to improve the transportability of the image-receiving sheet in the printer, a resin with excellent lubricity such as acrylic resin or acrylic silicone resin, or lubricious particles suitable for this resin, may be applied to the opposite side of the dye-receiving layer. In addition, e.g. 1-5 g
/rr? It is also preferable to form a slip layer with a certain thickness.

The thermal transfer sheet used when performing thermal transfer using the thermal transfer image-receiving sheet of the present invention as described above is one in which a dye layer containing a sublimable dye is provided on paper or polyester film, and conventionally known thermal transfer sheets are All can be used as they are in the present invention.

In addition, any conventionally known means for applying thermal energy during thermal transfer can be used, such as thermal printers (for example,
By controlling the recording time using a recording device such as 100-100), it is possible to sufficiently achieve the intended purpose by applying thermal energy of about 5 to 100 mJ/mrrf.

(Examples) Next, Examples and Comparative Examples will be given to explain the present invention in more detail. Note that parts and percentages in the text are based on weight unless otherwise specified.

Example 1 Foamed polypropylene (manufactured by Toyobo ■, Toyobar SS) with a thickness of 60 μm was bonded to both sides of coated paper (manufactured by Kanzaki Paper ■, New Top, basis weight 72.3 g/g, thickness 60 ttm) with adhesive. - Apply a coating solution with the following composition on the side with a bar coater at a drying rate of 5.0 g/r/, dry with a hair dryer, then heat in an oven at 80°C for 1 hour.
The dye-receiving layer was formed by drying for 0 minutes.

Pillar making! tile! Satoshi Katsu: Polyester (Byron 600, manufactured by Toyobo ■) 4,0
Part vinyl chloride/vinyl acetate copolymer (#1000A, manufactured by Denki Kagaku Kogyo ■) 6.0 parts Amino modified silicone (X-22-3050C1 Shin-Etsu Chemical ■
0.2 parts epoxy-modified silicone (X-22-3000E, Shin-Etsu Chemical Co., Ltd.)
Co., Ltd.) 0.2 parts methyl ethyl ketone/toluene (weight ratio 1/1) 89.6 parts Next, on the opposite side of the receptor layer, a coating solution having the following composition was applied with a bar coater to 1.0 g/rr when dry. A slip layer was formed by coating and drying at the following ratio to obtain a thermal transfer image-receiving sheet of the present invention.6 Acrylic resin 10 parts Teflon filler (particle size 2 μm) 5 parts Toluene 50 parts Methyl ethyl ketone 50 parts Example 2 Example 2 In place of the foamed polypropylene in 1, a thickness of 5
A thermal transfer image-receiving sheet of the present invention was obtained in the same manner as in Example 1 except that 0 μm foamed polypropylene (manufactured by Toyobo ■, Toyovar SS) was used.

Example 3 Instead of foamed polypropylene in Example 1, a thickness of 3
A thermal transfer image-receiving sheet of the present invention was obtained in the same manner as in Example 1 except that 5 μm foamed polypropylene (manufactured by Toyobo ■, Toyovar SS) was used.

Example 4 Coated paper (manufactured by Jujo Paper Co., Ltd., Diacoat, basis weight 127.9 g/g, thickness 120 μm) was used as the paper in Example 2.
A thermal transfer image-receiving sheet of the present invention was obtained in the same manner as in Example 2 except that

Example 5 Instead of foamed polypropylene in Example 1, a thickness of 2
A thermal transfer image-receiving sheet of the present invention was obtained in the same manner as in Example 1 except that 0 μm foamed polypropylene (manufactured by Toyobo ■, Toyovar SS) was used.

Example 6 Instead of foamed polypropylene in Example 1, a thickness of 5
A thermal transfer image-receiving sheet of the present invention was obtained in the same manner as in Example 1, except that 0 μm foamed polyethylene (Princil E, manufactured by Tanesui Kagaku ■) was used.

Example 7 Instead of foamed polypropylene in Example 1, a thickness of 5
A thermal transfer image-receiving sheet of the present invention was obtained in the same manner as in Example 1 except that 0 μm foamed polyethylene terephthalate (W-900 manufactured by Diafoil) was used.

Comparative Example I Foamed polypropylene (manufactured by Toyobo ■, Toyovar SS) with a thickness of 60 μm was attached with adhesive to only one side of coated paper (manufactured by Jujo Paper ■, Diacoat, basis weight 127.9 g/proof, thickness 120 μm). A thermal transfer image-receiving sheet of a comparative example was obtained in the same manner as in Example 1.

Comparative Example 2 Foamed polypropylene (manufactured by Toyobo ■, Toyovar SS) with a thickness of 20 μm was attached with adhesive to only one side of coated paper (manufactured by Jujo Paper ■, Diacoat, basis weight 127.9 g/board, thickness 120 μm). A thermal transfer image-receiving sheet of a comparative example was obtained in the same manner as in Example 1.

Example of use: A yellow dye sublimation thermal transfer sheet (manufactured by Dainippon Printing Co., Ltd.) and the thermal transfer image-receiving sheets of the present invention and the comparative example described above were superimposed with their respective dye layers and dye-receiving surfaces facing each other, and a heat-sensitive sublimation transfer printer was prepared. (vy-50, Hitachi manufactured rupture), a yellow image was formed by printing from the back side of the thermal transfer sheet with a thermal head at a printing energy of 90 mJ/mar, and magenta, cyan, and black images were sequentially superimposed. A full color image was formed by printing, and the results shown in Table 1 below were obtained.

(The following is a blank space) LU dark on j 0: Good ○: No practical problem △: Slightly poor ×: Poor (effect) According to the present invention as described above, foam layers are laminated on both sides of a core material such as paper. By increasing the cushioning properties of the cushion layer and forming cushion layers on both sides, it is possible to prevent curling during printing, and it is possible to form high-density and high-resolution images without uneven density or missing dots even in full-color image formation. became possible.

[Brief explanation of drawings]

FIG. 1 is a diagram schematically showing a cross section of an image receiving sheet of the present invention. Figure 1

Claims (3)

[Claims] (1) A thermal transfer image-receiving sheet comprising a base sheet and a dye-receiving layer formed on the surface thereof, wherein the base sheet has a structure in which foamed polyolefin layers are laminated on both sides of a core material. (2) The thermal transfer image-receiving sheet according to claim 1, wherein the core material is paper and the foamed polyolefin is foamed polypropylene. (3) The thickness of one foamed polyolefin layer is 30 to 80
The thermal transfer image-receiving sheet according to claim 1, having a total thickness of 100 to 300 μm.