JPH0655863A - Image receiving sheet for thermal transfer - Google Patents

Abstract

PURPOSE:To provide an image receiving sheet for thermal transfer which is difficult to cause thermal deformation without using the heat resistant base material. CONSTITUTION:An intermediate layer and an acceptance layer of dye are successively laminated on a base material sheet. The thermal conductivity of the base material sheet is regulated to <=0.13Kcal/m.h. deg.C. The intermediate layer is formed of resin having a thermal conductivity of 0.25Kcal/m.h. deg.C or below as a main body.

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 particularly to a thermal transfer image-receiving sheet which is excellent in the smoothness, strength, cushioning property and anti-curl property of a dye receiving layer and which forms an image of high density and high resolution. The purpose is to provide a seat.

[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]

Problems to be Solved by the Invention As a specific printing method in the sublimation type thermal transfer system as described above, a plastic sheet, a laminated sheet of a plastic sheet and paper, synthetic paper, natural paper or the like is used as a base sheet. , A thermal transfer image-receiving sheet formed by forming a dye receiving layer on these substrate sheets, and a thermal transfer film between the thermal head and the platen, while applying the amount of heat necessary for transferring the dye, while running under pressure contact. Form an image. Recently, with the downsizing of printers, the platen roll diameter has become smaller,
Therefore, the wrapping angle of the thermal transfer image-receiving sheet also tends to become acute, and with the increase in image sensitivity and density,
The amount of heat applied from the thermal head also tends to increase.

In accordance with these tendencies, the thermal transfer image receiving sheet in such a printing mechanism receives a large amount of heat when it is in a deformed state such as extreme bending, so that the thermal transfer image receiving sheet is transferred to the dye receiving layer and the base sheet which is the lower layer thereof. There is a problem such as curling of the thermal transfer image-receiving sheet due to the thermal damage of. As a method for solving such a problem, when a heat-resistant film such as a polyimide film, a polyarylate film, or a polyetherimide film is used as a base material sheet of a thermal transfer image-receiving sheet, thermal deformation or the like occurs due to a difference in heat storage property or the like. Although difficult, it is not practical as a base sheet for a thermal transfer image-receiving sheet due to problems such as difficult workability and high cost of the base sheet. Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art and to provide a thermal transfer image-receiving sheet in which thermal deformation does not easily occur without using a heat-resistant substrate sheet.

[0006]

The above object can be achieved by the present invention described below. That is, in the present invention, an intermediate layer and a dye receiving layer are sequentially laminated on a substrate sheet, and the thermal conductivity of the substrate sheet is 0.13 Kcal / m · h · ° C or less, and The layer has a thermal conductivity of 0.25 Kcal
A thermal transfer image-receiving sheet characterized by being formed mainly of a resin having a temperature of / m · h · ° C. or less.

[0007]

[Function] A base material sheet having a thermal conductivity of 0.13 Kcal / m · h · ° C or less is used, and an intermediate layer is mainly composed of a resin having a thermal conductivity of 0.25 Kcal / m · h · ° C or less. By forming as described above, curling at the time of printing can be prevented, and a flat printed matter having high density and high resolution after printing and having no curl can be easily provided.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described in more detail with reference to preferred embodiments. The substrate sheet used in the present invention has a thermal conductivity of 0.13 Kcal / m · h · ° C. or less, a general-purpose film generally used, for example,
Examples of the sheet include polyethylene terephthalate resin, polypropylene resin, polycarbonate resin, polyethylene resin, and the like, but foams of these films may also be used. The thermal conductivity of the base material sheet is 0.13 Kcal / m
If the temperature exceeds h · ° C, the image receiving sheet is likely to curl during printing.

The intermediate layer formed on at least one surface of the above-mentioned substrate sheet has a thermal conductivity of 0.25 Kcal / m.
It is formed mainly of a resin having a temperature of h · ° C. or less. Examples of such resin include, for example, polycarbonate resin, polypropylene resin, polyurethane resin, acrylic polyol resin, vinyl acetate resin, polyamide resin, polyolefin resin, polyester resin, phenoxy resin, nylon resin, polyvinylibutyral resin, polyvinyl acetoacetal. Resin etc. are mentioned. When the thermal conductivity of the resin for forming the intermediate layer exceeds 0.25 Kcal / m · h · ° C, the curl of the image-receiving sheet is likely to occur during printing.

Bubbles or a foaming agent such as microballoons may be contained in the intermediate layer to give the intermediate layer excellent heat insulating properties and cushioning properties. Further, the intermediate layer may contain a filler. Examples of the filler include inorganic fillers such as silica, alumina, clay, talc, calcium carbonate and barium sulfate, white pigments such as titanium oxide and zinc oxide, acrylic resins, epoxy resins, polyurethane resins, phenolic resins and melamine resins. Resin particles (plastic pigment) such as benzoguanamine resin, fluorine resin, and silicone resin. By adding these fillers to the intermediate layer,
Sufficient heat insulation and hardness can be given to the intermediate layer without increasing the thickness of the intermediate layer. The amount of the filler added is preferably in the range of 0 to 50% by weight of the weight of the intermediate layer.

The above resins and additives are mixed with acetone, ethyl acetate, methyl ethyl ketone, toluene, xylene,
A coating material or an ink is prepared by dissolving and dispersing in a suitable organic solvent such as cyclohexanone, and the coating material or the ink is prepared by forming means such as a gravure printing method, a screen printing method, a reverse roll coating method using a gravure plate, or the like. It is applied on a sheet, dried, and optionally crosslinked and cured to form an intermediate layer. The thickness of the intermediate layer thus formed is preferably 10% or less of the thickness of the substrate sheet, for example, about 0.5 to 20 μm.

The dye receiving layer formed on the surface of the intermediate layer is for receiving the sublimable dye transferred from the thermal transfer film and maintaining the formed image. Examples of the resin for forming the dye receiving layer include polyolefin resins such as polypropylene, polyvinyl chloride, vinyl chloride / vinyl acetate copolymers, ethylene / vinyl acetate copolymers, halogenated polymers such as polyvinylidene chloride. ,
Polyvinyl acetate, vinyl polymers such as polyacrylic esters, polyethylene terephthalate, polyester resins such as polybutylene terephthalate, polystyrene resins, polyamide resins, copolymer resins of olefins such as ethylene and propylene and other vinyl monomers, Examples thereof include ionomers, cellulosic resins such as cellulose diacetate, polycarbonates, and the like, and particularly preferable are vinyl resins and polyester resins.

Preferred releasing agents to be mixed with the above resins include silicone oils, phosphate ester type surfactants and fluorine type surfactants, with silicone oils being preferable. As the silicone oil, modified silicone oil such as epoxy modified, alkyl modified, amino modified, carboxyl modified, alcohol modified, fluorine modified, alkylaralkyl polyether modified, epoxy / polyether modified or polyether modified is desirable.

As the release agent, one type or two or more types are used. The amount of the release agent added is preferably 0.5 to 30 parts by weight with respect to 100 parts by weight of the dye-receiving layer forming resin. If the addition amount range is not satisfied, problems such as fusion of the dye layer and the dye receiving layer of the thermal transfer film or deterioration of printing sensitivity may occur. By adding such a releasing agent to the dye receiving layer, the releasing agent bleeds out on the surface of the receiving layer after transfer to form a releasing layer. The receptive layer is a dispersion prepared by dissolving, on the surface of the above-mentioned intermediate layer, a resin obtained by adding necessary additives such as a release agent to a suitable organic solvent or dispersing it in an organic solvent or water. Is 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, for the purpose of improving the whiteness of the dye receiving layer to further improve the sharpness of the transferred image, a fluorescent whitening agent, titanium oxide, zinc oxide, kaolin clay, calcium carbonate, A pigment such as fine powder silica or a filler can be added. The dye-receptive layer formed as described above may have any thickness, but is generally 1 to 50 μm.
The thickness is m. 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. As described above, the thermal transfer image-receiving sheet of the present invention can be formed by coating each layer on the base material sheet as described above.

[0016]

EXAMPLES The present invention will be further described with reference to Examples and Comparative Examples.
This will be specifically described. In addition, especially in the sentence, part or%
Unless stated otherwise, it is based on weight. First, thermal transfer image receiving sheet
Various coating liquids used for the constitution were prepared with the following formulations. Coating liquid for intermediate layer 1 Polycarbonate resin (Z-200, manufactured by Mitsubishi Gas Chemical Co., Ltd., thermal conductivity 0.16 Kcal / m · h · ° C.) 50 parts Toluene / methyl ethyl ketone (weight ratio 1/1) 50 partsCoating liquid for intermediate layer 2 Polyurethane resin (Takelac E-360, Takeda Pharmaceutical Co., Ltd., thermal conductivity 0.18 to 0.21 Kcal / m · h · ° C) 100 parts Effervescent microcapsules (F-80, Matsumoto Yushi-Seiyaku Co., Ltd.) 10 parts Acetic acid Ethyl / isopropyl alcohol (weight ratio 1/1) 400 partsIntermediate layer coating liquid 3 Polyvinyl acetoacetal resin (S-REC KS-5, manufactured by Sekisui Chemical Co., Ltd., thermal conductivity: 0.20 to 0.23 Kcal / m · h · ° C) 20 parts Polyisocyanate curing agent (Takenate D218, manufactured by Takeda Chemical Industries) 60 parts Toluene / Methyl ethyl ketone (weight ratio 1/1) 130 partsIntermediate layer coating liquid 4 Epoxy resin (Epicoat 1007, made by Yuka Shell, thermal conductivity 0.58 Kcal / m · h · ° C.) 30 parts Toluene / methyl ethyl ketone (weight ratio 1/1) 70 parts

Substrate sheet 1 ; polyethylene terephthalate film (S type 125 μm, made of dia foil,
Thermal conductivity 0.07 Kcal / m · h · ° C) Base material sheet 2 ; Foamed polypropylene film (Toyopearl SS-P4255, 80 μm, manufactured by Toyobo, thermal conductivity 0.03 Kcal / m · h · ° C) Coating for dye receiving layer Working solution : Vinyl chloride / vinyl acetate copolymer (# 1000D, manufactured by Denki Kagaku Kogyo) 100 parts Amino-modified silicone (X-22-343, manufactured by Shin-Etsu Chemical Co., Ltd.) 3 parts Epoxy-modified silicone (KF-393, Shin-Etsu Chemical Co., Ltd.) 3 parts) Methyl ethyl ketone / toluene (weight ratio 1/1) 500 parts

Examples 1 to 6 and Comparative Examples 1 to 2 The coating solution for the intermediate layer, the base sheet and the coating solution for the dye receiving layer were used in combination as shown in Table 1 below. After coating and drying the intermediate layer coating liquid on the surface at a ratio of a dry thickness of 3 μm, the dye receiving layer coating liquid is coated and dried on the intermediate layer to a dry thickness of 3 μm. Thermal transfer image-receiving sheets of the present invention and comparative examples were obtained. Using these thermal transfer image-receiving sheets, a printer (UP-500
No. 0 (manufactured by Sony) was used for full-screen dark solid printing, and the curl prevention properties of the obtained thermal transfer image-receiving sheet were examined. The results are shown in Table 1 below.

[0019]

[Table 1]

[0022]

According to the present invention as described above, the thermal conductivity is 0.1.
Adopting a base sheet having a temperature of 3 Kcal / m · h · ° C. or less and an intermediate layer having a thermal conductivity of 0.25 Kcal / m · h ·
By mainly forming a resin whose temperature is ℃ or less,
A curl at the time of printing is prevented, a high density and high resolution after printing, and a curl-free flat printed matter is easily provided.

Claims (2)

[Claims] 1. A base sheet comprising an intermediate layer and a dye receiving layer which are sequentially laminated on the base sheet, and the base sheet has a thermal conductivity of 0.1.
A thermal transfer image-receiving sheet, characterized in that the intermediate layer has a temperature of 3 Kcal / m · h · ° C or less and the intermediate layer is formed mainly of a resin having a thermal conductivity of 0.25 Kcal / m · h · ° C or less. 2. The thickness of the intermediate layer is 10 times the thickness of the substrate sheet.
The thermal transfer image-receiving sheet according to claim 1, which is not more than%.