JPH0825812A - Manufacture of heat transfer image receiving sheet - Google Patents

Abstract

PURPOSE:To provide a heat transfer image receiving sheet having excellent conveying properties, curl preventive properties after printing and excellent smoothness of a dye receiving layer with high productivity. CONSTITUTION:The one surface of a sheet base material is extrusion coated with polyethylene resin to manufacture a base material sheet. On the other hand, a dye receiving layer is formed on the one side surface of a foamed resin film via a primer layer to manufacture a surface layer sheet, an adhesive layer is formed on the surface no formed with the receiving layer of the front layer sheet, and the sheet surface of the base material sheet is opposed to the adhesive layer to be laminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer image-receiving sheet, and more specifically, it has excellent transportability and curl prevention after printing, and is capable of forming a high-density and high-resolution image without uneven density or missing dots in the image. An object is to provide a possible thermal transfer image receiving sheet.

[0002]

2. Description of the Related Art Conventionally, various thermal transfer methods are known. Among them, a sublimable dye is used as a recording agent, and this is carried on a base material sheet such as paper or a plastic sheet to form a thermal transfer sheet. There has been proposed a method of forming various full-color images on a thermal transfer image-receiving sheet that can be dyed with a dye, for example, a thermal transfer image-receiving sheet having a dye-receiving layer on the surface of paper or a plastic film.

In this case, a thermal head of a printer is used as a heating means, and a large number of three-color or four-color dots are transferred to a thermal transfer image-receiving sheet by heating for an extremely short time, and the original is formed by the multi-color dots. It reproduces a full-color image. The image formed in this way is
It is very vivid because the coloring material used is a dye,
And because it is excellent in transparency, the obtained image has excellent reproducibility and gradation of intermediate colors, is similar to the image by conventional offset printing or gravure printing, and has a high quality image comparable to a full color photographic image. It can be formed.

[0004]

The thermal transfer image-receiving sheet used in the sublimation type thermal transfer system as described above is excellent in transportability in the printer and in curl prevention after printing, and has no uneven density or missing dots in the image. In order to obtain high-density and high-resolution images, color development and density that accurately correspond to the thermal dot printing energy are required.
When the image receiving sheet is hard and lacks cushioning properties, the total thickness of the thermal head-thermal transfer sheet-image receiving sheet is not uniform, and the printing pressure of the thermal head becomes uneven, resulting in missing dots or uneven density in printing. The problem occurs.

As a method for solving such a problem, a method of laminating a cushion layer on one or both surfaces of a base sheet such as paper is known, and a method of using a foamed resin film as a cushion material has been proposed. There is. In the image receiving sheet as described above, a foamed resin film is laminated on one side or both sides of the base material with an adhesive. When these adhesives are used, an image receiving sheet obtained by a solvent of the adhesive or heating at the time of adhesion is obtained. Curling, waviness, etc. occur on the sheet, problems such as smoothness of the dye receiving layer and blisters occur when the dye receiving layer is provided on the surface, and solvent problems, heating process, aging time, etc. There is also a big problem. Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, to provide a heat transfer image-receiving sheet excellent in transportability and curl prevention property after printing, and also excellent in smoothness of a dye receiving layer with high productivity. That is.

[0006]

The above object can be achieved by the present invention described below. That is, according to the present invention, one surface of a paper base material is extrusion-coated with a polyethylene resin to prepare a base material sheet, and on the other hand, a dye receiving layer is formed on one surface of a foamed resin film via a primer layer. A thermal transfer image-receiving method characterized in that a surface layer sheet is produced, an adhesive layer is formed on a surface of the surface layer sheet on which a receiving layer is not formed, and the paper surface of the base material sheet is laminated on the adhesive layer so as to face it. It is a method of manufacturing a sheet.

[0007]

[Function] A polyethylene resin is extrusion-coated on one surface of a paper base material to form a curl prevention layer to form a base material sheet, while a dye receiving layer is formed on one surface of a foamed resin film via a primer layer. To produce a surface layer sheet, form an adhesive layer on the surface of the surface layer sheet on which the receiving layer is not formed, and laminate by facing the paper surface of the base material sheet to the adhesive layer, thereby curling, It is possible to provide a thermal transfer image-receiving sheet having no waviness and excellent smoothness of the receiving layer with high productivity.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described in more detail with reference to preferred embodiments. The thermal transfer image-receiving sheet of the present invention is produced by laminating a base sheet and a surface layer sheet by a dry lamination method. The base sheet is obtained by extrusion coating a polyethylene resin on one side of a paper base.

As the paper base material, various papers such as high quality paper, art paper, coated paper, cast coated paper, wallpaper, backing paper, synthetic resin or emulsion impregnated paper, synthetic rubber latex impregnated paper, synthetic resin internal addition Paper such as paper and paperboard is suitable, and the thickness of these paper base materials is arbitrary, but it is generally about 10 to 300 μm.

The polyethylene resin to be extrusion coated on one surface of the paper base material has a density of 0.935 g /
A polyethylene resin of m ³ or more is preferable, and by using such a polyethylene resin, thinning of the polyethylene resin layer is achieved, which is advantageous in terms of cost. Further, the higher the density of the polyethylene resin, the better the slipperiness (transportability) of the thermal transfer image-receiving sheet. The thickness of the polyethylene resin layer is preferably about 25 to 45 μm, and if it is thinner than this, the curl preventive property of the resulting thermal transfer image-receiving sheet is insufficient, while if it exceeds the above range, it is uneconomical.

Extrusion coating of the polyethylene resin may be carried out by a conventional method, but fine irregularities can be formed on the surface of the polyethylene resin layer formed by using a mat roll as a cooling roll immediately after coating. . By doing so, transportability such as blocking resistance and double-feeding prevention property of the resulting thermal transfer image-receiving sheet is improved. Such fine irregularities have a center line average roughness Ra of 0.
When the average number of protrusions per unit area (mm ² ) is 5 to 2.5 and the average number of protrusions is about 2,000 to 4,500, the above effect is further improved.

Ra is less than 0.5 or the number of protrusions is 4,500.
When it exceeds the above, when the thermal transfer image receiving sheets are piled up, the adhesion is improved with the dye receiving layer surface of the thermal transfer image receiving sheet below, and the friction coefficient is increased, and the transportability such as blocking prevention property and double feed prevention property is insufficient. Becomes Further, when Ra exceeds 2.5 or the number of protrusions is less than 2,000, the thermal transfer image-receiving sheet has good slipperiness (transportability), but it is not preferable because it causes a rough feel to the touch. Further, when the above-mentioned base material sheet is produced, the adhesiveness of the polyethylene resin layer can be improved by treating the paper base material with a corona discharge treatment, and the polyethylene resin coating layer is further subjected to a corona discharge treatment. By applying the mark, post-processing such as marking, antistatic treatment, gluing, and writing becomes easy to perform.

The surface layer sheet used in the present invention is obtained by forming a dye receiving layer on one surface of a foamed resin film via a primer layer. As the foamed resin film, a film such as foamed polypropylene, foamed polyethylene resin, or foamed polystyrene is used.
Foamed polypropylene is preferable in consideration of cushioning properties and the like. The density of these films is preferably 0.6 to 1.2. If the density is too high, the cushioning property will be insufficient, while if the density is too low, the strength will be insufficient.

The thickness of the foamed resin film is also important, and the preferable thickness is 30 μm to 80 μm, and 30 μm.
If the thickness is less than 3 μm, the foam layer is crushed severely after printing 3 to 4 times, causing problems of sensitivity such as uneven density, missing dots, and curling. On the other hand, if it exceeds 80 μm, cost, weight and transportability are increased. It is not preferable because

In the present invention, a primer layer is formed on one surface of the foamed resin film. This primer layer is used to improve the adhesion between the foamed resin film and the dye receiving layer formed thereon, and examples thereof include polyester resin, chlorinated polypropylene resin, modified polyolefin resin, urethane resin and polycarbonate resin. An acrylic resin, an ethylene-acrylate copolymer resin, an ethylene-methacrylic acid copolymer resin, an ionomer resin, a polyvinyl alcohol resin, a polyvinyl butyral resin, or the like is used alone or as a mixture. Further, a crosslinking agent such as polyisocyanate may be added to urethane resin or the like to be cured. Further, by adding a white pigment such as titanium oxide to the solution, it can also function as a masking layer for the dye receiving layer and give the dye receiving layer excellent whiteness. Such a primer layer is preferably formed in a solid content of about 0.5 to 10 g / m ² .

The dye receiving layer formed on the surface of the primer layer is for receiving the sublimable dye transferred from the thermal transfer sheet and maintaining the formed image. As the binder resin for forming the dye receiving layer, for example, polyolefin resin such as polypropylene, polyvinyl chloride, vinyl halide resin such as polyvinylidene chloride, polyvinyl acetate, vinyl resin such as polyacrylic ester, Polyethylene resin terephthalate, polyester resin such as polybutylene terephthalate, polystyrene resin, polyamide resin, copolymer resin of olefin such as ethylene and propylene and other vinyl monomers, ionomer, cellulose resin such as cellulose diacetate, Examples thereof include polycarbonate and the like, and particularly preferable ones are vinyl resins and polyester resins.

The above-mentioned dye receiving layer may be coated on the surface of the above-mentioned primer layer with the above-mentioned binder resin, for example, a release agent,
A dispersion obtained by adding necessary additives such as an antioxidant and an ultraviolet absorber to a suitable organic solvent or dispersing the dispersion in an organic solvent or water is used, for example, a gravure printing method, a screen printing method, a gravure printing method. It is formed by applying and drying by a forming means such as a reverse roll coating method using a plate.

The dye receiving layer preferably contains a releasing agent in order to impart a good releasing property to the thermal transfer sheet. Preferred releasing agents include silicone oils, phosphate ester type surfactants, fluorine type surfactants and the like, but silicone oils are preferable. Examples of the silicone oil include epoxy-modified, alkyl-modified, amino-modified, carboxyl-modified, alcohol-modified, fluorine-modified,
Modified silicone oils such as alkyl aralkyl polyether modified, epoxy / polyether modified, and polyether modified are desirable.

As the release agent, one type or two or more types are used. The amount of this release agent added is the amount of binder resin 1
1 to 20 parts by weight is preferable with respect to 00 parts by weight. If the addition amount range is not satisfied, problems such as fusion of the thermal transfer sheet and the dye receiving layer or reduction of printing sensitivity may occur. The dye receiving layer formed as described above may have any thickness, but it is generally 1 to 50 μm thick.
Further, such a dye receiving layer is preferably a continuous coating, but it may be formed as a discontinuous coating by using a resin emulsion or a resin dispersion.

In the present invention, heat drying is performed in forming the primer layer and the dye receiving layer. The drying temperature at this time is also important. If the drying conditions are severe, the foamed resin film as the base material shrinks. However, local unevenness occurs and the smoothness of the dye receiving layer is lost. Also, if the drying conditions are gentle, the shrinkage of the foamed resin film is small, but if the shrinkage is too small, when the final thermal transfer image-receiving sheet is printed, the heat supplied from the thermal head causes print curl. There is a problem of doing. In the present invention, by appropriately controlling the drying conditions at the time of forming the primer layer, the dye receiving layer, and further the adhesive layer,
By setting the shrinkage ratio in the range of 1.0 to 3.5%, it is possible to avoid the problems as described above at the time of bonding with the base material sheet and at the time of printing.

For laminating the surface layer sheet and the base material sheet as described above, an adhesive layer is formed on the surface of the surface layer sheet on which the dye receiving layer is not provided, and the paper surface of the base material sheet is opposed to the adhesive layer surface. Or a dry lamination method in which an adhesive layer is provided on the paper surface of the base sheet. As the adhesive, for example, an adhesive resin solution such as urethane-based, polyester-based, or polyether-based adhesive is applied to a desired surface, and the solvent is dried if necessary to form an adhesive layer. Such an adhesive layer is preferably formed as a solid content at a rate of about 0.5 to 10 g / m ² .

Dry lamination may be carried out by a conventionally known method. After coating the adhesive solution on the surface of the base sheet which is the first base paper by various coating methods, the adhesive solvent is evaporated in a drying tunnel, After forming a uniform adhesive layer containing no solvent on the surface of the base paper (depending on the surface properties and unevenness of the substrate, 1.5 to 5 g / m ² is preferable), it is the second base paper at the bonding part. It may be pressure-bonded to the surface layer sheet.

The total thickness of the thermal transfer image-receiving sheet obtained as described above is also important, and the total thickness is 100 to 3
The range of 00 μm is preferable, and even if it is thinner or thicker, it is not preferable in terms of waist, curl, weight, cost, transportability and the like. The thickness of the surface layer sheet is 5 to 40 of the total thickness.
% Is preferred. The thermal transfer image-receiving sheet obtained as described above is preferably subjected to antistatic treatment on one side or both sides.

The thermal transfer sheet used in the thermal transfer using the thermal transfer image-receiving sheet of the present invention as described above is a sheet in which a dye layer containing a sublimable dye is provided on a paper or a polyester film, and is conventionally known. Any thermal transfer sheet can be used as it is in the present invention. Further, as the means for applying the thermal energy at the time of thermal transfer, any conventionally known applying means can be used, for example, a thermal printer (for example,
By controlling the recording time with a recording device such as a video printer VY-100 manufactured by Hitachi, Ltd., it is possible to sufficiently achieve the intended purpose by applying thermal energy of about 5 to 100 mJ / mm ^2. I can.

[0025]

EXAMPLES Next, the present invention will be described more specifically with reference to Examples and Comparative Examples. In the text, parts and% are based on weight unless otherwise specified. Example 1 Coated paper (basis weight 127.9 g / m ² , NK high coat,
Corona treatment is applied to Nippon Paper Co., Ltd.), and polyethylene resin (density 0.938 g / cm ³ ) is applied at a processing temperature of 320.
A substrate sheet was prepared by extrusion coating at 37 ° C and a thickness of 37 ° C. At this time, the mat roll 1 was used as the cooling roll, and the center line average surface roughness Ra of the surface of the polyethylene resin layer was Ra.
Is 0.8 μm, and the average number of protrusions per unit area is 2955.
Pieces / mm ² (three-dimensional surface roughness meter, manufactured by Tokyo Seimitsu, SURF
It was measured by COM).

After a primer layer and a dye receiving layer having the following composition were dried on a foamed polypropylene film (40 MW647 manufactured by Mobil) having a thickness of 40 μm, 2 g / m ² and 4 g, respectively.
/ M ² was sequentially applied with a gravure coater, dried and laminated. Then, an adhesive having the following composition was applied to the surface opposite to the surface coated with the receptor layer so that the surface of the sheet was 5 g / m ² and dried to prepare a surface layer sheet). At this time, the shrinkage rate of the foamed resin film layer was 2.6%. The surface of the substrate sheet on which the polyethylene resin layer is not formed faces the adhesive layer of the surface layer sheet and is bonded by a dry laminator, and then the both sides of the obtained laminate are subjected to an antistatic treatment. Was used as the thermal transfer image-receiving sheet.

Composition for dye receiving layer : Polyester (Vylon 600, manufactured by Toyobo) 4.0 parts Vinyl chloride / vinyl acetate copolymer (# 1000A, manufactured by Denki Kagaku Kogyo) 6.0 parts Silicone (X-62- 1212, Shin-Etsu Chemical Co., Ltd.) 1.0 part Catalyst (PL50T, Shin-Etsu Chemical Co., Ltd.) 0.5 part Methyl ethyl ketone / toluene (weight ratio 1/1) 88.5 parts

Composition for primer layer : Urethane resin (Nipporan 5199, manufactured by Nippon Polyurethane Industry Co., Ltd.) 4.0 parts Titanium oxide 8.0 parts IPA / MEK / toluene (weight ratio 1/1/1) 60.0 parts Adhesion Composition for agent layer : Hydroxyl group-containing oligomer (Takelac A-969V, Takeda Pharmaceutical Co., Ltd.) 10.0 parts Isocyanate-containing oligomer (Takenate A-5, Takeda Pharmaceutical Co., Ltd.) 30.0 parts Ethyl acetate 60.0 parts

Example 2 The density of polyethylene resin in Example 1 was 0.952.
(DSC method) and the thickness of the polyethylene resin layer to 3
The thermal transfer image-receiving sheet of the present invention was obtained in the same manner as in Example 1 except that the thickness was changed to 2 μm. At this time, the center line average surface roughness Ra of the polyethylene resin layer surface was 0.8 μm, the average number of protrusions per unit area was 2789 pieces / mm ² , and the shrinkage rate of the foamed resin film layer was 2.6%. It was Example 3 The foamed resin film in Example 1 was replaced with a polypropylene foamed resin film of 35 μm (Toyopearl SS, manufactured by Toyobo), and the thickness of the polyethylene resin layer was 34 μm.
In the same manner as in Example 1 except that the thermal transfer image-receiving sheet of the present invention was obtained. At this time, the shrinkage rate of the foamed resin film layer was 2.5%.

Comparative Example 1 A foamed polypropylene film having a thickness of 60 μm (manufactured by Oji Oka Kasei Synthetic Paper, YUPO) was coated on both sides of a coated paper (manufactured by Kanzaki Paper Co., Ltd., New Top 72.3 g / m ² ) with an adhesive coating composition of Was applied, laminated and heat-cured by a three-roll reverse roll coating method to prepare a base material sheet. Incidentally, the adhesive was applied so that it would be 5 g / m ² after drying. Further, the same primer layer and dye receiving layer as in Example 1 were applied (drying conditions: 130 ° C. and 1 minute).

Adhesive layer composition : Hydroxyl group-containing oligomer (Takelac A-969V, Takeda Pharmaceutical Co., Ltd.) 10.0 parts Isocyanate-containing oligomer (Takenate A-5, Takeda Chemical Co., Ltd.) 30.0 parts Ethyl acetate 60. the primer layer and the slipping layer of 0 parts then following composition was respectively dry 0.2 g / m ² and was applied as a 0.8 g / m ² and the thermal transfer image-receiving sheet of Comparative example on the back side.

Lubricant layer composition : Acrylic resin (BR85, made by Mitsubishi Rayon) 10.0 parts Nylon 12 filler (MW330, made by Shinto Paint Co., Ltd.) 2.0 parts Methyl ethyl ketone / toluene (weight ratio 1/1) 88. Copy 0

Comparative Examples 2 to 5 A thermal transfer image-receiving sheet was prepared in the same manner as in Example 1 except that the drying temperature after coating the primer layer, the receiving layer and the adhesive layer in Example 1 was changed to the temperatures shown in Table 1 below. Got Evaluation method : Using the thermal transfer image-receiving sheets of the above Examples and Comparative Examples,
A gradation image is printed on a Sony color video printer UP5100, and the sensitivity and curl after printing are evaluated.
The results shown in Table 1 below were obtained.

Sensitivity : Color density of the same energy part is 105 as compared with Comparative Example 1.
% Or more is ◎, 95% to less than 105% is ◯,
Less than 95% to 90% △, less than 90% ×
Evaluated as. Color density was measured using a Macbeth color densitometer. Curl after printing : The thermal transfer image receiving sheet after 30 minutes of solid black printing was placed on a flat plate, and the heights of the four corners were measured to calculate an average value. The curl direction was based on the case where the receiving layer surface was facing up.

Table 1

[0036]

According to the present invention as described above, it is possible to provide with high productivity a thermal transfer image-receiving sheet which is free from curling and waviness and which is excellent in the smoothness of the receiving layer, the printing sensitivity, the curl prevention property after printing and the like.

Claims (4)

[Claims] 1. A substrate sheet is prepared by extrusion-coating a polyethylene resin on one surface of a paper substrate, while a dye receiving layer is formed on one surface of a foamed resin film via a primer layer to form a surface layer. A sheet is prepared, an adhesive layer is formed on a surface of the surface layer sheet on which the receiving layer is not formed, and the paper surface of the base material sheet is opposed to the adhesive layer and laminated by a dry lamination method. A method for manufacturing a thermal transfer image-receiving sheet. 2. The method for producing a thermal transfer image-receiving sheet according to claim 1, wherein the foamed resin film is laminated on the base material sheet in a state of being contracted by 1.0 to 3.5%. 3. The method for producing a thermal transfer image-receiving sheet according to claim 1, wherein the foamed resin film is a foamed polypropylene film. 4. The polyethylene resin has a density of 0.935 g /
The method for producing a thermal transfer image-receiving sheet according to claim 1, which is a polyethylene resin having a cm ³ or more.