JPH11157227A - Thermal transfer recording sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the dislocation of an image receiving layer part during the image forming period of time, and also prevent the gloss of a transferred image receiving part from becoming extraordinarily high by forming an intermediate layer containing at least a binder resin and a filler between a base material and an image receiving layer. SOLUTION: The base material can include a laminated base material of foam film or synthetic paper and cellulose paper. The intermediate layer is formed of binder resin and a filler to form an excellent adhesiveness between the base and the image receiving layer. Since the binder resin is needed to give an appropriate adhesiveness in an interface between the image receiving layer and the intermediate layer, it is preferable to be polyurethane resin. The filler is preferable to be particles of silicone resin as inorganic particles. For the image receiving layer, conventional one can be employed s a dye transfer method. By the use of the intermediate layer, an adhesiveness is controlled between the base material and the image receiving layer for preventing the shift of the image receiving layer part, or regulating the degree of luster.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate capable of forming an arbitrary image with a heat transferable dye or a sublimable dye and transferring the formed image onto an arbitrary paper or sheet-like molded product. A heat transfer sheet is provided.

[0002]

2. Description of the Related Art In recent years, as a method for obtaining a color hard copy, a thermal transfer recording method has rapidly spread due to its simplicity, low cost of an apparatus, and ease of maintenance. Because hard copies can be obtained, a dye transfer method using a heat transferable dye or a heat sublimable dye has attracted attention. In this method, a heat transfer recording sheet having a coloring material layer mainly composed of a dye such as a heat transfer dye or a sublimable dye and a binder resin on one surface of a base film is heated from the back side by a heating means such as a thermal head. Then, the dye is transferred onto an image receiving body having an image receiving layer containing a dye-dyeing resin as a main component on the surface of a substrate, and recording is performed. This method is used for television,
It is used as a video image output device and a computer graphic image output device.
It has been attracting attention as an image output device for print proof using a computer.

[0003]

As described above, the dye transfer method can easily obtain a high-definition color hard copy.
Due to the restriction that the transfer receiving material for dyes is limited to dye-dyeable materials such as polyester resin, it is necessary to coat the surface with dye-dyeable resin even on transfer paper for print proof. There is. However, a variety of papers are usually used as the printing paper for printing proof, and it is extremely troublesome to provide a dye-dyeable resin on the surface of each paper each time, and it is also necessary to prepare in advance. However, it is not practical because many types of transfer paper coated with a dye-dyeing resin must be prepared.

Therefore, as a method for solving the problem,
For example, a method is conceivable in which an image is formed in advance on a heat transfer sheet dedicated for dye transfer, and the image is retransferred to paper actually used for printing (Japanese Patent Application Laid-Open No. 62-2387).
No. 91, JP-A-63-78795). The heat transfer sheet for dye transfer used in the re-transfer method, a heat transfer sheet provided with a peelable image receiving layer on one surface of a sheet-shaped substrate is used, but usually the image receiving layer To facilitate transfer or peeling, a release layer is provided between the peelable image-receiving layer and the sheet-like substrate. However, if such a release layer is provided to facilitate peeling, when an image is formed on the dedicated paper, the image receiving layer floats up from the sheet-like substrate, or shifts from the sheet-like substrate, and furthermore, Or peel off. Conversely, it has been proposed to provide an adhesive layer instead of a release layer so that the image receiving layer does not shift during image printing (Japanese Patent Application Laid-Open No. 62-23 / 1987).
No. 8791). However, if the adhesive layer is provided in such a manner, the image receiving layer does not slip when the image is printed, but when the printed image is re-transferred onto the receiving paper, the transfer is not smoothly performed, and the image receiving layer is completely transferred. Or the dedicated receiving paper may be torn when the dedicated receiving paper is peeled off.

In the case where a release layer formed only of a normal resin binder is used, an image is formed on an image receiving layer formed on the release layer, and then the image is transferred onto a transfer paper such as plain paper. The surface of the transferred image receiving layer has a very high gloss. Therefore, if the surface of the transfer receiving paper to which the image receiving layer is transferred is a high gloss film or super art paper, the gloss of the image portion is similarly high, so that there is no difference in gloss there, and there is no particular feeling of foreignness. However, if the transfer paper is made of art paper, coated paper, or plain paper that is not too glossy, only the image part will have a high gloss, and it will feel like a separate photo has been pasted, and you will feel uncomfortable Is generated. In particular, in the case of a color proof, which has recently been used for a dye transfer system in which images are very photographic and beautiful, such a tendency is remarkably observed. As printing paper, polyethylene terephthalate film, polypropylene film, vinyl chloride film, various plastic films such as cellophane, and various papers, such as high-gloss super art paper, art paper with low gloss, coated paper, Various types of paper are used, including plain paper with low gloss, and even very low gloss such as newsprint. There is a problem that the difference in gloss of the non-image area becomes noticeable. Therefore, there has been a demand for the development of a transfer-receiving material in which the image receiving layer portion does not shift during image formation, and the gloss of the transferred image receiving layer portion is not abnormally high.

[0006]

Means for Solving the Problems As a result of intensive studies on the above problems, the present inventors have found that a heat transfer sheet having a peelable image receiving layer provided on one side of a substrate has a structure between the substrate and the image receiving layer. By providing an intermediate layer containing a filler, the image receiving layer is not displaced during image formation, and the surface gloss of the retransferred image receiving layer is not so high. It has been found that the difference in gloss between the image and the image-receiving portion is not noticeable and an image with a natural feeling can be obtained.

That is, according to the present invention, an intermediate layer containing at least a binder resin and a filler is provided between a base material and an image receiving layer in a heat transfer sheet having a peelable image receiving layer provided on one surface of a base material. The heat transfer sheet is characterized in that: Hereinafter, the present invention will be described in detail.
The basic configuration of the heat transfer sheet of the present invention is that an intermediate layer containing at least a binder resin and a filler is provided on one surface of an arbitrary sheet-like base material, and a peelable image receiving layer is provided thereon. Features. By forming the heat transfer sheet of the present invention in such a configuration, an arbitrary image is formed on the image receiving layer by the heat transfer sheet having a heat transferable dye, and then the image to be transferred, such as paper or a sheet-like molded product, is formed. The above-mentioned drawbacks of the prior art are basically solved by superimposing the images so as to overlap and thermally transferring the images by means such as a laminator. At this time, the image is reversed left and right, which means that when the image is first formed on the heat transfer sheet, the image is formed on the final transfer object by turning the image left and right in advance. Can be a normal image.

Next, the present invention will be described in detail with respect to the material and the method of forming the heat transfer sheet of the present invention. Examples of the sheet-like base material include a plastic film such as polypropylene, polyethylene terephthalate, or polycarbonate, or a foamed film or synthetic paper such as a polypropylene-based or polyethylene terephthalate-based material, or a base material laminated with the plastic film or foamed film and cellulose paper. Can be used. Above all, a substrate obtained by laminating a foamed film or synthetic paper with a cellulose paper is preferable because the occurrence of curl due to thermal shrinkage of the substrate during printing is small and the image density is high during printing.

The intermediate layer comprises at least a binder resin having good adhesion to the substrate and the image receiving layer, and a filler. Polyurethane resin, polyacrylate resin, polyester resin,
Polyamide resins, ethylene / vinyl acetate copolymer resins, etc. can be used, but polyurethane resins are preferred because they can stably disperse the filler and provide appropriate adhesiveness at the interface between the image receiving layer and the intermediate layer. As the filler, inorganic or organic particles can be used. Examples of the inorganic particles include titanium oxide, calcium carbonate, and clay, and titanium oxide is particularly preferable. Examples of the organic particles include particles of a silicone resin, an acrylic resin, a fluororesin, and the like, and particles of a silicone resin are particularly preferable. Examples of the shape of the particles include crushed particles and spherical particles, and spherical particles are particularly preferable. The particle size is 0.0
It is preferably from 5 to 1 μm, and more preferably from 0.1 to 0.5 μm.

The weight ratio between the binder resin and the filler is 6
0:40 to 80:20 is preferred. When the ratio of the binder resin is less than 60, the adhesiveness between the intermediate layer and the image receiving layer is too high, and when the image receiving layer is transferred to paper or the like, peeling between the image receiving layer and the intermediate layer hardly occurs, and the forcible peeling is attempted. Then, the receiving paper and the receiving paper are easily broken. Conversely, when the ratio of the binder resin is more than 80, the glossiness of the transferred image receiving layer surface is increased, and the gloss difference between the surrounding transfer paper and the transferred image receiving layer surface is more conspicuous. The adhesiveness to the image receiving layer is low, and the image receiving layer is easily shifted from the intermediate layer or peeled off when printing an image on the image receiving layer.

The purpose of the intermediate layer is to control the adhesiveness between the substrate and the image receiving layer, but it may also have a cushioning function and a heat insulating function. Thereby, the image density becomes uniform when the image is formed on the image receiving layer, and the image density can be increased. The thickness of the intermediate layer is usually 0.
It is 2 to 10 μm, preferably 0.3 to 6 μm, and more preferably 0.5 to 3 μm.

As the image receiving layer, those generally used as a dye transfer system are used. Usually, a resin for dyeing the dye to fix the dye and a transfer sheet for forming an image are formed by thermal transfer. A release agent is used as an essential component to prevent heat fusion when printing with the head. As the dye-dyeing resin, various resins such as polyester resin, vinyl chloride-vinyl acetate copolymer, polycarbonate resin, cellulose resin, and polyvinyl acetal resin can be used. Polyvinyl acetal-based resin is preferred because of its moderate adhesiveness. These dye-dyeable resins can be mixed with other resins within a range that does not impair the performance,
The mixing ratio of the other resin may be 50% or less, preferably 40% or less of the resin component.

As the releasing agent, silicone oil, various fluorine compounds, higher fatty acid compounds, waxes and the like are used, and silicone oil is particularly preferable. Further, in the image receiving layer, various sensitizers such as a silicone varnish for denaturation to increase the density of the image, the adhesiveness with the substrate, the purpose of improving the heat resistance of the image receiving layer, or the surface of the release agent. A hardening agent or the like for assisting bleed-out of the ink may be added. As the curing agent, isocyanate, epoxy resin, melamine resin and the like can be used, and polyfunctional isocyanate is particularly preferable.

As a particularly preferred formulation of the image receiving layer, a polyvinyl acetal resin, a modified silicone oil and a polyfunctional isocyanate are contained at least, and 0.2 to 5 parts of the modified silicone oil is added to 100 parts by weight of the polyvinyl acetal resin. A composition containing 1 to 10 parts of a polyfunctional isocyanate is exemplified. In addition, an ultraviolet absorber, a light stabilizer, an antioxidant, a fluorescent brightener, an antistatic agent, a crosslinking accelerator, and the like may be added to the image receiving layer. The thickness of the image receiving layer is usually 0.5 to 20 μm, preferably 1 to 10 μm, more preferably 2 to 6 μm as a dry coating film.

As a method for forming the intermediate layer and the image receiving layer, the above-mentioned components are dissolved in an appropriate solvent, and if particles are contained, they are dispersed by an appropriate dispersing method if necessary, and each coating solution is prepared. Prepare. Next, an intermediate layer coating liquid is first applied to the substrate and dried, and then an image receiving layer coating liquid is applied thereon and dried, and then, if necessary, heated to perform aging. The purpose of aging is to promote bleed-out of the release agent in the image receiving layer to the surface and to promote a crosslinking reaction when a curing agent is used in the image receiving layer or the intermediate layer.

As the solvent for preparing the coating solution, various organic solvents having good solubility in the resin and various additives used in the present invention can be used. For example, alcohol solvents such as methanol, ethanol, and isopropanol; aromatic solvents such as toluene and xylene; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; ester solvents such as ethyl acetate and butyl acetate; tetrahydrofuran and dioxane Or a mixed solvent thereof.

The coating method can be arbitrarily selected from commonly used methods. For example, a method using a reverse roll coater, a gravure coater, a microgravure coater, a rod coater, an air doctor coater, or the like is used. The sublimable dye used in the color sheet for thermal transfer recording used together with the transfer paper of the present invention includes azo, anthraquinone, nitro, styryl, naphthoquinone, quinophthalone, azomethine,
Various nonionic sublimable dyes such as coumarins and condensed polycyclics are used.

[0018]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples unless it exceeds the gist thereof. In the examples, “parts” indicates “parts by weight”.

Example 1 (a) Preparation of Transferred Paper Coating Liquid for Intermediate Layer Polyurethane Varnish (manufactured by Mitsubishi Chemical Corporation, 65 parts, trade name: HE-6021, solid content concentration: 25 wt%) Titanium oxide (Ishihara Sangyo Co., Ltd.) 35 parts Toluene 5 parts Methyl ethyl ketone 10 parts Isopropyl alcohol 5 parts Image receiving layer coating liquid polyvinyl phenyl acetal resin 100 parts Denaturing silicone varnish 50 parts (Toshiba Silicone) (Trade name: TSR-160, solid content concentration: 60 wt%) Amino-modified silicone oil 2.5 parts (trade name: KF-393, manufactured by Shin-Etsu Chemical Co., Ltd.) Polyfunctional isocyanate compound (produced by Mitsubishi Chemical Corporation) 5 parts Trade name Mytec NY-710A, solid content concentration 75 wt%) Toluene 300 parts Methyl ethyl keto 300 parts

The intermediate layer coating solution having the above composition was applied to a synthetic paper made of polypropylene having a thickness of 150 μm with a wire bar and dried to obtain a coating film having a dry thickness of about 2 μm. On the intermediate layer, the coating solution for the image receiving layer was further applied by a wire bar and dried to obtain a coating having a dry thickness of about 4 μm. Then 1
Heat treatment was performed in an oven at 00 ° C. for 12 hours to prepare a heat transfer sheet of the present invention. The polyvinyl phenyl acetal resin is polyvinyl alcohol (with a saponification degree of 99).
(Mol%, degree of polymerization: 1700) by acetalization with phenylacetaldehyde, and had the following structural formula.

[0021]

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(B) Preparation of color sheet A biaxially stretched polyethylene terephthalate film (6 μm thick) having a heat-resistant lubricated back surface on the ink-coated surface is provided with 5 parts of a magenta sublimation dye represented by the following structural formula (A): Acrylonitrile-styrene (AS) resin (manufactured by Denki Kagaku Kogyo KK, trade name Denka AS-S), 10 parts, toluene 8
An ink composed of 5 parts and 10 parts of cyclohexanone was applied and dried to form a color material layer having a dry film thickness of about 1 μm, thereby producing a color sheet.

[0023]

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(C) Transfer Recording Test The ink-coated surface of the above color sheet is superimposed on the heat transfer sheet prepared in (a) above, using a thin film type line thermal head having a heating resistor density of 8 dots / mm. ,
Recording was performed under the following conditions. At that time, the image receiving layer had no abnormality at the time of printing, and a recorded matter having a color density of 1.82 was obtained. Recording line density 8 lines / mm Applied power of thermal head 0.4 W / dot Applied pulse width of thermal head 5 ms (d) Transfer test of paper to be transferred onto paper (Art paper), laminated under the following conditions under the following conditions: Laminator (manufactured by MC Corporation, device name: Halder Laminator MRK)
-650Y). Roll temperature 120 ° C. Pressing pressure 2 kg / m ² Feed rate 70 cm / min. When the image receiving paper was peeled off from the receiving paper, the inverted image was clearly transferred on the receiving paper. In addition, the surface of the image had low gloss and was an image having a natural feeling.

Comparative Example 1 A heat transfer sheet and a color sheet were prepared and tested in the same manner as in Example 1 except that no intermediate layer was provided. As a result, the image receiving layer was not displaced or peeled off during printing, and a beautiful printed matter having a color density of 1.80 was obtained. Next, the printed matter was overlapped on the transfer paper (art paper) so that the image portion was in contact with it, and subjected to heat lamination in the same manner as in Example 1. As a result, the transfer transfer sheet was stuck to the transfer paper. When the paper could not be peeled off and was forcibly peeled off, the transferred paper was torn.

Comparative Example 2 A heat transfer sheet and a color sheet were prepared and tested in the same manner as in Example 1 except that no titanium oxide was added to the coating liquid for the intermediate layer. As a result, the image receiving layer was slightly displaced between the intermediate layer and the image receiving layer during printing, but a beautiful print having a color density of 1.80 was obtained. Next, the printed matter in which the shifted image was returned to the original state was overlaid so that the image portion was in contact with the transfer paper (art paper), and was subjected to thermal lamination processing in the same manner as in Example 1. The image was clearly transferred. However, the surface of the image was very glossy, had a different gloss from the surrounding transfer paper, and was not natural.

Example 2 A heat-receiving sheet and a color sheet were produced in the same manner as in Example 1, except that the amount of the polyurethane resin in the coating solution for the intermediate layer was 40 parts and the amount of titanium oxide was 60 parts. Was prepared and tested. As a result, the image receiving layer was not displaced or peeled off during printing, and a beautiful printed matter having a color density of 1.80 was obtained. Next, the printed matter was overlapped on the transfer paper (art paper) so that the image portion was in contact with it, and subjected to heat lamination in the same manner as in Example 1. As a result, the transfer transfer sheet was stuck to the transfer paper. Peeling was very heavy. When peeled off slowly and slowly, it came off, but the transferred paper was partially torn.

[0028]

According to the thermal transfer sheet of the present invention, the image receiving layer does not shift or peel off during printing with the thermal transfer sheet. An image with a small difference in gloss and a natural feeling can be obtained. Therefore, when using the dye transfer method for printing proof, even when using various papers,
There is almost no difference in gloss between the image portion and the non-image portion, and an excellent effect of obtaining a proof with a natural feeling is obtained.

Claims (5)

[Claims] 1. A heat transfer sheet having a peelable image receiving layer provided on one surface of a substrate, wherein an intermediate layer containing at least a binder resin and a filler is provided between the substrate and the image receiving layer. To be transferred. 2. The heat transfer sheet according to claim 1, wherein the weight ratio between the binder resin and the filler contained in the intermediate layer is from 60:40 to 80:20. 3. An image receiving layer according to claim 1, wherein said image receiving layer comprises a composition containing a polyvinyl acetal resin as a main component.
Or a heat transfer sheet according to item 2. 4. The image receiving layer contains at least a polyvinyl acetal resin, a modified silicone oil and a polyfunctional isocyanate, and 0.2 to 10 parts of the modified silicone oil per 100 parts by weight of the polyvinyl acetal resin. The heat transfer sheet according to claim 3, wherein the composition contains 1 to 10 parts of 5. The intermediate layer according to claim 1, wherein the binder resin is mainly composed of a polyurethane resin.
The heat transfer sheet according to any one of the above.