JPH06210968A - Thermal transfer image receiving sheet and production thereof - Google Patents

Abstract

PURPOSE:To provide a thermal transfer image receiving sheet having sufficient surface smoothness and forming a sharp image free from a defect such as missing dots and having density in thermal transfer using a sublimable dye. CONSTITUTION:In a thermal transfer image receiving sheet produced by forming a resin layer containing at least an air bubble layer and a dye receiving layer on at least one surface of a base material sheet, smoothing treatment is applied to the air bubble layer and/or the dye receiving layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a thermal transfer image receiving sheet, and more specifically, to provide a thermal transfer image receiving sheet capable of forming a recorded image excellent in surface smoothness, color density and sharpness. And

[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 a sublimable dye is used as a thermal transfer sheet by supporting it on a base material sheet such as polyester film. Transferable material that can be dyed, for example,
There has been proposed a method of forming various full-color images on a thermal transfer image-receiving sheet having a dye-receptive layer formed on paper or plastic film. In this case, the thermal head of the printer is used as the heating means, and a large number of three-color or four-color dots are transferred to the thermal transfer image-receiving sheet by heating for an extremely short time, and the full-color image of the original is formed by the multicolor dots. Is to be reproduced. The image formed in this way is very clear because the coloring material used is a dye and has excellent transparency, so the resulting image has excellent reproducibility of intermediate colors and gradation, and It is possible to form a high quality image which is similar to the image by offset printing or gravure printing and which is comparable to a full color photographic image.

[0003]

In order to effectively carry out the above-mentioned thermal transfer method, not only the structure of the thermal transfer sheet but also the structure of the thermal transfer image-receiving sheet for forming an image are important. The above-mentioned thermal transfer image-receiving sheet is conventionally provided with a primer layer (adhesive layer) and an intermediate layer (for example, a bubble-containing cushion layer, a barrier layer, etc.) on the surface of a base material sheet as an essential layer thereon. Manufactured by forming a dye-receiving layer, or alternatively,
A dye-receptive layer is formed on the surface of the base film so that it can be peeled off.
A dye-receptive layer transfer film having an intermediate layer (which may also serve as an adhesive layer) or an adhesive layer, etc. formed thereon as necessary is prepared, and the adhesive layer of this film is used as a base sheet for a thermal transfer image-receiving sheet. It can also be manufactured by a so-called transfer method in which it is attached to the surface of the substrate and then the base film is peeled off.

In any of the above methods, when a resin layer containing at least a cell layer and a dye receiving layer is formed on a substrate sheet or a substrate film, the formed cell layer is formed by foaming a foaming agent or the like. It is unavoidable that irregularities occur on the surface, and therefore, even if a dye receiving layer is formed on the surface, the irregularities cannot be sufficiently eliminated. The presence of irregularities on the dye-receiving layer makes it unsuitable for applications where surface smoothness is required for the image, and during image formation, a large number of fine particles are present between the dye-receiving layer and the dye layer of the thermal transfer sheet. There is a problem that such voids occur and defects such as white spots occur in the formed image. Therefore, the object of the present invention is to
An object of the present invention is to provide a thermal transfer image-receiving sheet which is sufficiently smooth on the surface in a thermal transfer method using a sublimable dye, has no defects such as white spots, and gives a clear image with a high density.

[0005]

The above object can be achieved by the present invention described below. That is, the present invention is a thermal transfer image-receiving sheet formed by forming a resin layer containing at least a bubble layer and a dye receiving layer on at least one surface of a substrate sheet,
The thermal transfer image-receiving sheet and the method for producing the same are characterized in that the bubble layer and / or the dye-receiving layer are subjected to a smoothing treatment.

[0006]

By forming the bubble layer on the substrate sheet or forming the entire layer and then smoothing the surface, a recorded image having excellent surface smoothness, color density and sharpness can be formed. It is possible to provide a thermal transfer image-receiving sheet.

[0007]

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 has a resin layer containing at least a cell layer and a dye receiving layer formed on at least one surface of a substrate sheet, and the cell layer and / or
Alternatively, it can be obtained by subjecting the dye receiving layer to a smoothing treatment. Examples of the base sheet used in the present invention include synthetic paper (polyolefin-based, polystyrene-based, etc.), high-quality paper, art paper, coated paper, cast-coated paper, wallpaper, backing paper, synthetic resin or emulsion-impregnated paper, synthetic rubber latex. Films or sheets of various plastics such as impregnated paper, synthetic resin internal paper, paperboard, cellulose fiber paper, polyolefin, polyvinyl chloride, polyethylene terephthalate, polystyrene, polymethacrylate, polycarbonate, etc. can be used, and their synthesis is also possible. A white opaque film formed by adding a white pigment or a filler to a resin, a foamed foamed sheet, or the like can also be used and is not particularly limited.

Further, a laminated body made of any combination of the above-mentioned substrate sheets can also be used. As an example of a typical laminated body,
Examples include synthetic paper made of cellulose fiber paper and synthetic paper or cellulose fiber paper and plastic film or sheet. The thickness of these substrate sheets may be arbitrary, for example,
The thickness is generally about 10 to 300 μm. The substrate sheet as described above is preferably subjected to a primer treatment or a corona discharge treatment on the surface when the adhesion with the dye receiving layer formed on the surface is poor. The bubble layer formed on at least one surface of the above-mentioned substrate sheet is preferably formed from a coating liquid comprising a resin having good cushioning properties and a foaming agent, and in a preferred embodiment an aqueous coating liquid is used as the coating liquid. use. Further, an organic solvent may be added to and mixed with the aqueous coating liquid used in order to accelerate the drying after coating. As a resin with good cushioning and adhesiveness to the base material,
For example, polyurethane resin, acrylic resin, polyethylene resin, butadiene rubber, epoxy resin, a two-component curing type polyurethane adhesive such as used for laminating films, a dry laminating material such as an epoxy adhesive, etc. Adhesives, vinyl acetate resins for wet laminating, ethylene-vinyl acetate copolymer-based, polyamide-based, polyester-based, polyolefin-based hot-melt adhesives and the like can be advantageously used.

As the foaming agent or bubbles to be contained in the above-mentioned liquid for coating the bubble layer, dinitropentamethylenetetramine, diazoaminobenzene, azobisisobutyl which decomposes by heating to generate gases such as oxygen, carbon dioxide and nitrogen. Any known foaming agent such as decomposition type foaming agent such as ronitrile or azodicarbamide, or microspheres in which low boiling point liquid such as butane or pentane is microencapsulated with resin such as polyvinylidene chloride or polyacrylonitrile can be used. Further, a foam in which these microspheres are preliminarily foamed, a foam covered with a white pigment, or the like can be effectively used.

The foaming agent may be foamed during or after the formation of the cell layer or after the desired layer is formed thereon.
In addition, bubbles such as microspheres that have been foamed to some extent may be dispersed in the coating liquid in advance. The amount of the above-mentioned foaming agent or foam used is preferably such that, when heated to 90 ° C. to 140 ° C., the bubble layer has a thickness of about 1.1 to 4 times. The formation of the bubble layer may include a coating liquid or an organic solvent having, as a medium, the binder resin and the foaming agent, or an organic solvent in which bubbles are dissolved or dispersed, on at least one surface of the substrate sheet. Using a water-based coating solution, other necessary additives such as white pigment,
Fillers, adhesives, cross-linking agents, curing agents, catalysts, ultraviolet absorbers, antioxidants, those added with light stabilizers, for example,
It is carried out by applying and drying by a forming means such as a gravure printing method, a screen printing method and a reverse roll coating method using a gravure plate. The thickness of the bubble layer formed is preferably about 2 to 30 μm.

As an example of the organic solvent which may be used as a drying accelerator when an aqueous coating liquid is used, it has a relatively low boiling point and latent heat of vaporization, has an azeotropic property with water, and is vaporized. Sometimes organic solvents that have less problems with odor or toxicity are preferable, for example, methyl alcohol, ethyl alcohol,
Propyl alcohol, butyl alcohol, methyl ethyl ketone, acetone, ethyl acetate, butyl acetate, ethyl lactate, toluene, xylene and the like can be mentioned, but when the coating liquid contains bubbles such as microspheres, Those that tend to dissolve the resin that is the wall material of the bubbles, such as acetone, ethyl acetate, butyl acetate,
Ethyl lactate, toluene, xylene etc. should not be used. The content of these organic solvents is about 100 parts by weight of water. It is preferable to use it in a proportion of 10 to 200 parts by weight. If the amount of the organic solvent used is too small, the drying acceleration effect is not sufficient, while if it is too large, the advantage of using the aqueous coating liquid is lost.

In the present invention, the above-mentioned coating liquid is applied on a substrate sheet in a desired coating amount and then dried by heating to foam the foaming agent or expandable bubbles contained in the foam layer. A bubble layer can be formed, and after the bubble layer is formed, surface smoothing treatment can be performed. As the surface smoothing treatment method, calender treatment for smoothing the surface of the bubble layer through a base sheet having a bubble layer formed between a pair of rolls provided with a certain clearance is suitable, and at this time, suitable for the pair of rolls. You can apply heat and pressure. The smoothing treatment differs depending on the thickness of the base material, the thickness of the cell layer, the degree of unevenness of the cell layer, the expansion ratio of the cell layer, etc., so it cannot be specified unconditionally. It is preferably in the range of about 5 to 20%. Incidentally, the smoothing treatment is not limited after the formation of the bubble layer as described later.

The dye receiving layer formed on the surface of the bubble layer is for receiving the sublimable dye transferred from the thermal transfer sheet and maintaining the formed image. Examples of the thermoplastic resin for forming the dye receiving layer include polyolefin resins such as polypropylene, halogenated polymers such as polyvinyl chloride and polyvinylidene chloride, polyvinyl acetate, ethylene / vinyl acetate copolymer, vinyl chloride.・ Vinyl acetate copolymers, vinyl resins such as polyacrylic ester, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polystyrene resins, polyamide resins, olefins such as ethylene and propylene, and other vinyl monomers. Examples thereof include polymer-based resins, ionomers, cellulose-based resins such as cellulose diacetate, polycarbonate-based resins, polybutynyl acetal-based resins, and the like.

The dye-receptive layer contains other necessary additives such as a releasing agent, a cross-linking agent and a curing agent in addition to the above thermoplastic resin.
A catalyst, a heat release agent, an ultraviolet absorber, an antioxidant, a light stabilizer, and the like are added or dissolved in a suitable organic solvent, for example, a general-purpose organic solvent such as toluene, methyl ethyl ketone, or a mixture thereof. The dispersed coating liquid can be applied and dried by a forming means such as a gravure printing method, a screen printing method, a reverse roll coating method using a gravure plate, and the like.

In the formation of the dye receiving layer, titanium oxide, zinc oxide, kaolin clay, calcium carbonate, fine powder silica, etc. are used for the purpose of improving the whiteness of the dye receiving layer and further improving the sharpness of the transferred image. Pigments and fillers can be added. 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 forming the dye receiving layer, a barrier layer or the like may be provided in advance on the surface of the bubble layer in order to prevent migration of the release agent to the bubble layer. The same smoothing process may be performed. The smoothing treatment may be performed in the same manner as above after forming the dye receiving layer, or both the smoothing treatment of the bubble receiving layer and the smoothing treatment of the dye receiving layer may be performed. The surface roughness Ra after the smoothing treatment is 2.8.
μm or less, Pt is 27.0 μm or less, Rz is 18.0 μm
m or less is preferable. In this way, a surface smoothness comparable to or better than normal copy paper is achieved.

In the present invention, a thermal transfer image-receiving sheet similar to the above can be manufactured by a transfer method. That is, for example, when using pulp paper or the like as the substrate sheet, the substrate sheet may lack surface smoothness,
In this case, the coating method may cause irregularities or pinholes or the like in the bubble layer or dye receiving layer formed,
According to the transfer method, such a problem does not occur. The transfer method is, for example, by forming the dye receiving layer on the film surface of polyester film or the like having a good releasability, and further forming the above-mentioned bubble layer on the surface thereof, and further, if necessary, a suitable pressure-sensitive adhesive layer. Alternatively, an adhesive layer is formed in advance, the pressure-sensitive adhesive layer is made to face the surface of the base material sheet such as the pulp paper and bonded by a laminator or the like, and then the polyester film is peeled off. In this method, the smoothing treatment may be performed after the formation of the bubble layer, or may be performed from the surface of the dye receiving layer after the transferable resin layer is transferred to the surface of the substrate sheet.

Further, the thermal transfer image-receiving sheet of the present invention can be selected from various materials such as sheet-like or roll-shaped thermal transfer image-receiving sheet, cards, transmissive original preparation sheet, etc., which can be subjected to thermal transfer recording, by appropriately selecting a substrate sheet. It can also be applied to applications.
Further, the thermal transfer image-receiving sheet of the present invention may be provided with other layers such as a barrier layer between the bubble layer and the dye receiving layer for preventing migration of the release agent in the dye receiving layer, if necessary. . The thermal transfer sheet used when performing thermal transfer using the thermal transfer image-receiving sheet of the present invention as described above is a paper or polyester film provided with a dye layer containing a sublimable dye, and a conventionally known thermal transfer sheet is Both can be used as they are in the present invention.

As the means for applying the heat energy during the thermal transfer, any conventionally known applying means can be used, for example, a recording device such as a thermal printer (for example, a video printer VY-100 manufactured by Hitachi, Ltd.). By controlling the recording time,
By applying thermal energy of about 00 mJ / mm ² , the intended purpose can be sufficiently achieved.

EXAMPLES Next, the present invention will be described more specifically with reference to examples. In the text, parts and% are based on weight unless otherwise specified. Example 1 As a base material sheet, synthetic paper (manufactured by Oji Yuka, thickness 110 μm)
m) is applied to one surface of the coating solution for a bubble layer having the following composition by a wire bar at a rate of 10.0 g / m ² when dried, and then dried, and the following coating for a dye receiving layer is performed. The working solution was applied and dried at a rate of 5.0 g / m ² when dried with a wire bar to obtain a thermal transfer image-receiving sheet of the present invention. In addition, the foaming treatment of the bubble layer is 10 m in length and 15 in temperature.
0 ° C., wind speed 10 m / min. Transport speed of 50 m / min. It went on condition of. During this manufacturing process, the pressure was 10 kg / cm ² , and the calender roll temperature was 10
0 ° C. and speed 50 m / min. The results shown in Table 1 below were obtained by carrying out a calendering treatment under the above conditions.

Composition of coating liquid for bubble layer: resin emulsion (AE932, made by Japan Synthetic Rubber, solid content 52.5%) 500 parts Microcapsule type foaming agent (Expansel 551DE80, made by Nippon Ferrite Co., Ltd.) 100 parts water 100 parts Dye-receiving layer coating liquid composition: Polyester ester resin (Vylon 200, manufactured by Toyobo) 100 parts Amino-modified silicone (KF-393, manufactured by Shin-Etsu Chemical Co., Ltd.) 3 parts Epoxy-modified silicone (X-22-343, Shin-Etsu Chemical) Industrial) 3 parts Methyl ethyl ketone / toluene (1: 1) 900 parts

Example 2 A thermal transfer image-receiving sheet of the present invention was obtained in the same manner as in Example 1, except that the following coating liquid was used in place of the bubble layer coating liquid. After forming the dye receiving layer in this manufacturing process, the pressure was 10 kg / cm ² , the calender roll temperature was 100 ° C., and the speed was 50 m / min. The results shown in Table 1 below were obtained by carrying out a calendering treatment under the above conditions. Coating composition for cell layer; resin emulsion (AE932, made by Japan Synthetic Rubber, solid content 52.5%) 500 parts Foaming agent (Microsphere F50, made by Matsumoto Yushi-Seiyaku Co., Ltd.) 50 parts Water 100 parts

Example 3 The surface of a 12 μm-thick polyester film (trade name “Lumirror”, manufactured by Toray) was coated with the dye-receptive layer coating solution of Example 1 at 3.0 g / m ² when dried with a bar coater. The coating solution for the bubble layer of Example 1 is coated on the dye receiving layer in the same manner as above, after being dried with a drier temporarily and then dried in an oven at 100 ° C. for 30 minutes. Then, it was coated and dried in the same manner as in Example 1 at a rate of 10 g / m ² when dried to form an air bubble layer to obtain a dye-receiving layer transfer film used in the present invention. After stacking the above dye-receiving layer transfer film on the surface of a copy paper (Xerox M paper, thickness 90 μm) and passing both through a laminator,
The base film was peeled off and the dye receiving layer was transferred to obtain the thermal transfer image-receiving sheet of the present invention. During this manufacturing process, the pressure was 10 kg / cm ² , the calender roll temperature was 100 ° C., and the speed was 50 m / min. The results shown in Table 1 below were obtained by carrying out a calendering treatment under the above conditions.

[0022]

[Table 1]

Measuring method of smoothness : JIS B 601
According to (1982), a surface roughness measuring device (manufactured by Tokyo Seimitsu Co., Ltd.
Center line average roughness (Ra), maximum height (Rt), and 10-point average roughness (R) using Surfcom 570A-3DF).
z) was measured. The unit of Ra, Rt, and Rz is μm.
Is. When I measured copy paper as the reference paper,
Ra = 2.40-2.80 μm, Rt = 24.0-2
7.0 and Rz = 16.0 to 18.0 μm, and in the case of Examples and Comparative Examples, the results are shown in Table 2 below.

[0024]

[Table 2]

The evaluation was carried out by comparing the measured values in Table 2 with the measured values in the case of copy paper. That is, if the measured value is generally larger than that of the copy paper, x, if the measured value is similar, Δ,
The one with a small numerical value was evaluated as ○. Image quality evaluation method : CP-1 manufactured by Mitsubishi Electric as a printer
CG-931 manufactured by Kenwood was used as an image supply source, a standard color print CR10S print cartridge for CP-10 was used as the dye transfer film, and each example, comparative example and CD-10S print paper were used as the image receiving paper. . Color pattern generator CG-
All the built-in image patterns of 931 are input to the CP-10 by using the NTSC composite video signal terminal, and the image is printed, and the image quality is visually judged for color unevenness, density, white spots, and dot sharpness. . The ones equivalent to the standard were evaluated as ◯, those slightly inferior to the standard were evaluated as Δ, and the ones that were severely uneven and were significantly inferior to the standard were evaluated as x.

Example 4 An ethylene-vinyl acetate copolymer emulsion (XB-408) was used instead of the resin of the coating liquid for the bubble layer in Example 1.
No. 5, manufactured by Toa Paint Co., Ltd.) was used, and otherwise the same as in Example 1 to obtain a thermal transfer image-receiving sheet of the present invention. At this time, the smoothness and image quality of the dye receiving layer were the same as in Example 1. Example 5 An emulsion-based adhesive (E-1054, manufactured by Soken Chemical Co., Ltd.) was used in place of the resin of the coating liquid for the bubble layer in Example 2, and the same as in Example 2 except that the thermal transfer image-receiving of the present invention was performed. Got the sheet. At this time, the smoothness and image quality of the dye receiving layer were the same as in Example 2.

[0027]

[Effects] According to the present invention as described above, the surface smoothness, the color density and the sharpness can be improved by performing a smoothing treatment on the surface after forming the bubble layer on the substrate sheet or after forming all layers. A thermal transfer image-receiving sheet capable of forming an excellent recorded image can be provided.

Claims (7)

[Claims] 1. A thermal transfer image-receiving sheet comprising a substrate sheet and a resin layer containing at least a bubble layer and a dye receiving layer formed on at least one surface of the substrate sheet, wherein the bubble layer and / or the dye receiving layer is subjected to a smoothing treatment. A thermal transfer image-receiving sheet characterized by being provided. 2. A method of manufacturing a thermal transfer image-receiving sheet comprising a base sheet and a resin layer containing at least a bubble layer and a dye receiving layer formed on at least one surface of the base sheet, and a smoothing treatment step in the step of forming the resin layer. A method for producing a thermal transfer image-receiving sheet, which comprises: 3. After the formation of the bubble layer, the bubble layer is smoothed,
Next, the method for producing a thermal transfer image-receiving sheet according to claim 2, wherein another layer is formed. 4. The method for producing a thermal transfer image-receiving sheet according to claim 2, wherein the smoothing treatment is performed after forming all the resin layers. 5. A dye-receptive layer transfer film having a transferable resin layer containing at least an air bubble layer and a dye-receptive layer formed on the surface of a base film, is attached to a base sheet of a thermal transfer image-receiving sheet, and then the base film is attached. A method for producing a thermal transfer image receiving sheet, which comprises peeling a material film, comprising a step of forming the resin layer or a smoothing treatment step after transferring the resin layer. 6. The method for producing a thermal transfer image-receiving sheet according to claim 5, wherein after the formation of the bubble layer, the bubble layer is smoothed. 7. The method of manufacturing a thermal transfer image-receiving sheet according to claim 5, wherein the smoothing treatment is performed after the transfer of the resin layer.