JP2690122B2 - Method of manufacturing heat transfer sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is applicable to thermal transfer recording in which an image is formed by combining a thermal transfer sheet and a thermal transfer sheet to perform thermal printing according to image information with a thermal head or the like. The present invention relates to a method for manufacturing a heat transfer sheet used.

[Conventional technology]

In recent years, with the development and popularization of electronic image recording systems such as video cameras, it has become possible to record high-sensitivity and high-quality images as electric signals. Also, due to advances in computer graphics, it is possible to create sophisticated images. Has become. One of the image recording methods of this type is a thermal transfer recording method. In this method, a thermal transfer sheet and a thermal transfer sheet are superposed between a thermal head and a platen roll, in which a large number of fine heating elements are arranged, and the thermal transfer sheet and the thermal transfer sheet are passed while being pressed to perform recording. Two thermal transfer recording methods have been developed: a melt transfer type and a sublimation transfer type. Of these, the sublimation transfer type is one in which the dye or dye precursor sublimes from the transfer sheet to the heat-transferred sheet due to heat, vaporizes or melts and transfers, and if the size of the energy during heating is controlled, It can be varied to give continuous halftones, and by changing the hue of the dye on the thermal transfer sheet, a natural color photographic image consisting of an overlay of each color (eg cyan, magenta, yellow and black) can be obtained. Since it can be formed, demand is increasing as a material for making an image signal into a hard copy.

[Problems to be solved by the invention]

By the way, the conventional thermal transfer sheet used in the above-mentioned sublimation type thermal transfer recording system has the following problems to be solved. That is, the dye receiving layer of a conventional heat transferable sheet is generally formed by applying a solution of a dye receiving layer resin to a base sheet by using a gravure printing method.

However, when the dye receiving layer is formed by gravure printing, the gravure roll plate remains on the surface of the dye receiving layer,
Since it became matte, it lacked luster and sometimes impaired aesthetics. Further, even if the dye receiving layer is formed by using a roll coater or a bar coater, it is not possible to obtain a smoothness equal to or higher than the smoothness of the roll, and in the process of evaporating the solvent in the dye receiving layer resin, There is also a drawback that the surface of the dye receiving layer becomes rough and becomes matte. Then, the drying conditions for evaporating the solvent were adjusted and super calender treatment was conducted, but sufficient gloss and smoothness could not be obtained.

In addition, the present applicants previously applied a metal roll to the surface of the dye receiving layer and applied an elastic roll to the surface on the opposite side to apply pressure to the surface of the dye receiving layer before printing the dye image on the dye receiving layer surface. It was found that the smoothness of the can be improved and applied. However, in this method, when the temperature of the metal roll surface is appropriate, the effect of enhancing the smoothness is high, but if the temperature of the metal roll surface is too high, the resin that constitutes the dye-receiving layer will be thermally fused to the metal roll. It had the drawback of wearing it. The effect of increasing the surface smoothness of the dye image-receiving layer of the heat-transferable sheet by applying pressure is extremely high when the temperature of the resin forming the temperature dye-receiving layer at the time of pressing is Tg or more, preferably Tg + 10 ° C. or more. However, at this temperature, the dye image-receiving layer resin often heat-bonds to the pressure roll or the pressure plate.

The present invention has been proposed in order to solve the above-mentioned problems of the prior art, and an object thereof is thermal transfer capable of efficiently imparting gloss and smoothness to the surface of the thermal transfer sheet during the manufacturing process. It is to provide a method for manufacturing a sheet.

[Means for solving the problem]

In order to achieve the above object, the present inventor, in the process of manufacturing a heat transferable sheet, at least the dye receiving layer surface of the sheet, by superposing a plastic sheet or film having thermoplasticity, by heating and pressing,
It has been found that excellent gloss and smoothness can be imparted.

That is, the method for producing a heat transferable sheet of the present invention is characterized by the following points.

(1) In a method for producing a heat-transferable sheet that receives a dye or a dye precursor that can be transferred by sublimation, vaporization or dissolution by heat, in at least the dye receiving layer surface of the sheet before transfer of the dye or dye precursor, A plastic sheet or film having thermoplasticity is laminated, heated and pressed, and then the plastic sheet or film is removed from the surface of the dye receiving layer to obtain a thermal transfer sheet having gloss and smoothness on the surface of the dye receiving layer. A method for producing a heat-transferable sheet, which comprises:

(2) A heat-transferable sheet having a heating temperature in the heat and pressure treatment that is equal to or higher than Tg of the dye receiving layer resin and is lower than a temperature at which a thermoplastic plastic sheet or film is heat-sealed to a heat source. Production method.

(3) The Tg of the thermoplastic plastic sheet or film is the Tg of the dye receiving layer resin of the thermal transfer sheet.
A method for manufacturing a higher thermal transfer sheet.

The term "dye" as used in the present invention refers to a general dye used in a sublimation type thermal transfer recording system, and under normal handling conditions, the color material does not transfer even when it comes into contact with the receiving layer (for example, 100 ° C). It means a dye which causes a transition of a coloring material by sublimation, vaporization, dissolution, etc. for the first time (by the above heating). Examples of such dyes include azo type, nitro type,
It is used by appropriately selecting from various dyes such as disperse dyes typified by anthraquinone type and quinoline type, basic dyes typified by triphenylmethane type, fluorane type and oil-soluble dyes.

Further, as the dye precursor, any of those conventionally used for pressure-sensitive paper and thermal paper can be applied, and triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based, and spiropyran-based ones are preferably used. To be done. When a dye precursor is used as a colorant that can be transferred from the transfer sheet, a developer for the dye precursor is contained in the dye receiving layer of the heat transfer sheet.

Further, the dye receiving layer in the thermal transfer sheet of the present invention is a layer capable of receiving the dye transferred from the thermal transfer sheet during thermal transfer, for example, polyester,
Conventionally, a resin used for sublimation type thermal transfer recording such as polyurethane, vinyl chloride-vinyl acetate copolymer polystyrene, acrylic, polyamide, and polycarbonate is appropriately selected and formed.

Further, the substrate sheet carrying the dye receiving layer in the heat-transferable sheet of the present invention is, for example, softwood, hardwood, hemp,
Resin Coated Pap made from natural paper made from camellia, trifurcation, cotton, etc., and laminated with resin such as polyethylene
Art paper, coated paper or synthetic paper coated with white filler, synthetic film, plastic film, sheet, etc. are used, but particularly preferably polypropylene foam, polyethylene terephthalate foam, synthetic paper having a paper-like layer, etc.・ A foamable plastic sheet with heat insulation properties. The plastic sheet or film having thermoplasticity used in the method for producing a thermal transfer sheet of the present invention,
The one having a Tg (glass transition temperature) higher than that of the surface of the dye receiving layer is used. The plastic sheet or film is superposed on at least the dye receiving layer surface of the heat transferable sheet.For example, even when the heat transfer sheet is pressed at a high temperature so that the receiving layer side of the heat transferable sheet hits the metal roll, the plastic sheet or film is laid on the metal roll. It is possible to effectively impart gloss and smoothness to the surface of the dye-receiving layer by cooling the film in the atmosphere and peeling off the plastic sheet without heat-sealing the surface of the receiving layer of the heat transferable sheet. It is a thing.

Examples of the thermoplastic plastic sheet or film used in the present invention include the following.

For example, polyethylene terephthalate film, polycarbonate film, etc. polyester system; amide film, etc. polyamide system; nitrocellulose film, triacetate film, diacetate film, etc., cellulose derivative; polyethylene film, polypropylene film, etc. polyolefin system; polyvinyl chloride film, polyvinylidene chloride Examples thereof include halogenated polymers such as: polyphenylene sulfide film; polyvinyl butyral, polyvinyl acetoacetal and the like polyvinyl acetal; polyvinyl alcohol film, but not limited thereto.

The surface of the thermoplastic plastic sheet or film in the present invention may be imparted with releasability, and as a method thereof, for example, a releasing agent such as silicone oil is applied to the surface of the thermoplastic plastic sheet or film. It is also possible to polymerize a resin that imparts releasability such as polysiloxane to the resin that substantially constitutes the thermoplastic sheet or film, but is not limited to these as long as the same effect can be obtained. It is not something that will be done.

The surface of the plastic sheet or film in the present invention preferably has high smoothness. Particularly preferably, the Bekk smoothness is 2,000 sec or more.

The surface of the thermoplastic plastic sheet or film of the present invention which is in contact with a heating roll or a heating press machine may be heat-treated. As the method, for example, a metal foil may be laminated or a reaction-curable resin or the like may be applied, but the method is not limited to this as long as the same effect can be obtained.

The thermoplastic plastic sheet or film of the present invention has a cushioning property when the thermoplastic transfer sheet or film used for sublimation-type thermal transfer recording is superposed and heated and pressed. The effect of imparting gloss and smoothness to the surface of the layer is high, but if necessary, a layer having a higher cushioning property than that of the base sheet or film is provided on the surface of the thermoplastic plastic sheet or film or as an intermediate layer. May be. Examples of the layer having a high cushioning property include a urethane foam layer, but are not limited to this.

The thermoplastic sheet or film in the present invention may be one kind, or a plurality of sheets or films may be stacked or used in parallel.

When the thermoplastic plastic sheet or film used in the present invention is used for winding, it is superposed on the heat-transferable sheet by attaching a guide roller or the like so that wrinkles do not occur. It is also possible to repeatedly use an endless thermoplastic plastic sheet or film.

In the present invention, the heat-transferable sheet to which gloss and smoothness are imparted may be provided with a cushioning layer between the dye receiving layer and the base sheet or on the side of the base sheet opposite to the dye receiving layer.

When a cushioning layer is provided on the heat transferable sheet, the effect of imparting gloss and smoothness is enhanced by the method of the present invention.

The pressurizer used in the present invention is not particularly limited as long as it can perform the method of the present invention, but a method of applying pressure between at least two rolls is preferable in view of versatility of the apparatus. Further, it is preferable that one of the two rolls is a metal smooth roll whose temperature can be adjusted, and the other is a smooth elastic roll. However, even if the two rolls are both metal rolls, preferable results can be obtained by laminating a thermoplastic plastic sheet or film on the surface of the heat transferable sheet opposite to the dye receiving layer.

As the heating method in the present invention, it is preferable to use a metal smooth roll whose temperature can be adjusted as described above, but for example, heating may be performed with a hot pressing plate, far infrared rays, warm air, or the like. It does not matter as long as the purpose can be achieved.

Further, a cooling drum or a cool air fan may be provided behind the two rolls, which can be heated and pressed, in the feeding direction for the purpose of cooling the heat-transferred sheet. The heat pressurization treatment or the cooling treatment may be performed any number of times.

[Action]

According to the present invention, a thermoplastic plastic sheet or film is superposed on at least the surface of the dye receiving layer of the heat transferable sheet and heated and pressed, so that if the surface of the dye receiving layer is heated and pressed as it is, a pressure roller or The dye-receptive layer does not heat-bond to the surface of the pressure roller or the pressure plate even at a high temperature such that it heat-bonds to the pressure plate. Also, due to the cushioning properties of the plastic sheet or film having thermoplasticity, it is possible to impart extremely effective gloss and smoothness to the surface of the dye-receiving layer by peeling it off from the dye-receiving layer after cooling. Becomes

Hereinafter, specific contents of the present invention will be described in detail with reference to examples.

[Example-1] Using a synthetic paper (manufactured by Oji Yuka: Yupo FPG150) having a thickness of 150 µm as a base sheet, and using a wire bar on one side of the base sheet, the composition for forming a receiving layer having the following composition After coating and drying, a receiving layer having a coating amount of 8 g / m ² when dried was provided to obtain a heat-transferable sheet. Receptor layer forming composition Polyester resin 10 parts by weight (Toyobo: Byron 200) Amino-modified silicone 0.5 parts by weight (Shin-Etsu Chemical: KF-393) Epoxy-modified silicone 0.5 parts by weight (Shin-Etsu Chemical: X-22-343) Solvent 89 parts by weight (toluene / methyl ethyl ketone = weight ratio 1/1) 100 μm thick polyethylene terephthalate sheet (Lumira T manufactured by Panac Industrial Co., Ltd.) on the dye receiving layer surface and the back surface of the heat transferable sheet obtained by the above method. Type) are overlaid and a mini super calendar (Yuri Roll Machine Co., Ltd., MEC-3) is used. Roll temperature 60 ° C, linear pressure 2
Under the condition of 00 kg / cm, the metal roll surface was heated and pressed so that the dye receiving layer surface side was brought into contact with the surface. After air-cooling for 20 seconds, the polyethylene terephthalate sheet was peeled off, and the dye receiving surface of the heat transfer sheet having a very high gloss was obtained.

[Comparative Example-1] A desired glossiness was obtained by hot pressing under the same conditions as in Example 1 without laminating the polyethylene terephthalate sheet on the heat-transferred sheet obtained in the same manner as in Example 1. Moreover, the heat-transferred sheet was greatly curled.

[Example-2] A synthetic paper having a thickness of 60 µm (made by Oji Yuka:
YUPO FPG) is coated with polyurethane adhesive on one side (10 g / m ² dry weight), dried, and then fine-quality paper (rice basis weight 85
(g / m ² ) are superposed and pressed between hot rolls at a temperature of 90 ° C. for sticking. Further, the above polystyrene aqueous solution is applied and dried on the surface of the high quality paper on which the synthetic paper is not stuck, A sheet was used in which the same synthetic paper as the synthetic paper was attached in the same manner. Then, a polyurethane emulsion (Hodogaya Chemical Co., Ltd .: Iserax S-1040) was diluted with water to a concentration of 25% by weight on one surface of the synthetic paper as the base material, stirred with a homomixer and foamed. The emulsion thus obtained was applied by Meyer bar coating and dried to form a porous layer having a thickness of 4 μm (a solid content of 6 g / m ² ) as an intermediate layer having cushioning properties. Further, on the upper surface of the intermediate layer of the base sheet, a receptive layer-forming composition having the following composition is applied using a wire bar and dried, and a receptive layer having a dry coating amount of 8 g / m ² is provided to form a heat transferable sheet. Obtained. Receptor layer forming composition Polyester resin 40 parts by weight (Toyobo: Byron 600) Vinyl chloride vinyl acetate copolymer resin 60 parts by weight (Denka Vinyl 1000A) Amino-modified silicone 0.3 parts by weight (Shin-Etsu Chemical: X -22-3050C) Epoxy-modified silicone 0.9 parts by weight (Shin-Etsu Chemical: X-22-3000T) Methyl ethyl ketone / toluene 700 parts by weight (weight ratio 1/1) Example 1 was applied to both sides of the heat transfer sheet obtained by the above method. The same polyethylene terephthalate sheets as in 1 above were superposed and heat pressed at a roll temperature of 80 ° C. as in Example 1.

The surface of the dye receiving layer of the heat transferable sheet obtained in Example 2 was a very beautiful mirror surface, and high glossiness and smoothness were obtained.

[Comparative Example 2] The same heat-pressing as in Example 2 was applied to the heat-transferable sheet obtained in the same manner as in Example 2 without laminating the polyethylene terephthalate sheet. Has fused to the hot metal roll.

The glossinesses of the dye receiving layer surfaces of the heat transfer sheets of Example-1, Example-2, Comparative example-1, Comparative example-2, and untreated-1 and untreated-2 are shown below.

As can be seen from the table, an example in which thermoplastic plastic sheets or films were superposed and heated and pressed
In 1 and 2, very good results were obtained. On the other hand, in Comparative Examples 1 and 2 which were subjected to only heat pressure treatment without superimposing plastic sheets or films having thermoplasticity, heat fusion occurred when the temperature of the metal roll was high, and gloss was also increased. It wasn't so good. Further, in the untreated-1,2 in which the plastic sheets or films having thermoplasticity were not overlapped and the heat and pressure treatment was not performed, the glossiness obtained was very low.

[Effects of the Invention] As described above, according to the present invention, in the process of manufacturing a heat-transferable sheet, plastic sheets or films having thermoplasticity are superposed, heated and pressed, and then the dye-receiving layer of the heat-transferred sheet is received. Since the layer resin is separated from the heat and pressure source, it is possible to prevent heat fusion, and it is possible to obtain a heat transferable sheet having extremely high gloss and smoothness due to the cushioning effect of the sheet or film.

Further, since the smoothness of the heat-transferred sheet is increased, it is possible to obtain an excellent dye image in which the dye dots are not missing due to printing.

Claims (3)

(57) [Claims] 1. A method for producing a heat transferable sheet that receives a dye or a dye precursor capable of being transferred by sublimation, vaporization or dissolution by heat, wherein at least the dye receiving layer surface of the sheet before the transfer of the dye or the dye precursor. , A plastic sheet or film having thermoplasticity is superposed, heated and pressed, and then the plastic sheet or film is removed from the dye receiving layer surface, whereby gloss and smoothness are imparted to the dye receiving layer surface. A method for producing a heat-transferable sheet, which comprises obtaining a heat-transferable sheet. 2. The heating temperature in the heat and pressure treatment is in the range of Tg or higher of the dye receiving layer resin and lower than the temperature at which the plastic sheet or film having thermoplasticity is heat-sealed to the pressure source. The method for producing a heat-transferable sheet according to claim 1, wherein 3. The method for producing a thermal transfer sheet according to claim 1, wherein the Tg of the thermoplastic plastic sheet or film is higher than the Tg of the dye receiving layer resin of the thermal transfer sheet.