JP2002356066A - Thermal transfer receiving sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-cost thermal transfer receiving sheet having excellent printing suitability for various thermal printers. SOLUTION: Between a support and a thermal transfer dye receiving layer,
An intermediate layer containing a resin having a glass transition point of −50 ° C. to 25 ° C. is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer receiving sheet. More specifically, the present invention is suitable for a thermal printer, especially a thermal transfer printer for sublimation dyes, has a good image quality, can obtain an image similar to a silver halide photograph, and is advantageous in terms of cost. Sheet).

[0002]

2. Description of the Related Art In recent years, a thermal printer, particularly a dye thermal transfer printer capable of printing a clear full-color image, has attracted attention. Dye thermal transfer printers superimpose a receiving layer containing a dye-dyeable resin of a receiving sheet on a dye ink sheet, and apply heat at a predetermined concentration of the dye layer on the receiving layer by heat supplied from a thermal head or the like. To form an image. The ink sheet used for this printer is a dye sheet of three colors of yellow, magenta and cyan, or a dye sheet of four colors obtained by adding black to the three colors. A full-color image is obtained by repeatedly transferring the dyes of each color of the ink sheet to the receiving sheet in order.

[0003] In such a printer with a thermal head, a dye-dyeable resin is mainly used on a sheet such as a uniaxially or biaxially stretched film or a multilayer structure film (for example, synthetic paper) in order to obtain good printed images. In many cases, a receiving sheet having an image receiving layer formed therein is used. The receiving sheet as described above has a uniform thickness, is flexible, and in many cases, has an advantage such as a higher heat insulating property as compared with paper made of cellulose fiber because of having a heat insulating void layer. Therefore, there is an advantage that a uniform and high-density transfer image can be obtained. However, when thermal transfer recording is performed on a receiving sheet using a stretched film or a multilayer structure film as a sheet-like substrate as described above, the stress generated by the stretching of the film is released by heat, and the film contracts due to heat. There are drawbacks such as curling and wrinkling of the sheet, making traveling in the printer difficult, and significantly reducing the commercial value of the resulting print.

[0004] In order to improve the problems derived from the sheet-like base material, the uniaxially or biaxially stretched film or the multilayer structure film is coated on both sides of a core material having a small heat shrinkage such as paper. Attempts have been made to control the occurrence of curl of the substrate by laminating and balancing the tension of the films on the front and back of the substrate. However, in such a receiving sheet having a multilayer structure, for example, the heat of the drying process at the time of coating the receiving layer causes the substrate constituting film to undergo thermal contraction, resulting in curling of the receiving sheet and significantly lowering the commercial value. There were drawbacks, such as causing

Further, paper is used as a core material, and on both sides thereof,
When a substrate is formed by laminating the uniaxially or biaxially stretched film or the multilayer structure film, irregularities based on the fiber shape of the paper surface are also transferred onto the film surface, and this irregularity prevents the transfer of heat of the recording head. Since the image was uniform, white spots and the like occurred in the image portion, and a sufficiently clear image quality could not be obtained. Furthermore, since a step of laminating a paper substrate and a film layer is required, the cost is high. A receiving sheet (Japanese Patent Publication No. 4-48120) has been proposed in which an intermediate layer containing a resin having a specific modulus as a main component is interposed between a paper or plastic film support and a receiving layer.
This defines the physical properties of the intermediate layer at room temperature, and does not necessarily correlate with the printing suitability of the receiving layer when heated by the thermal head.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a low-cost thermal transfer receiving sheet having excellent printability for various thermal printers.

[0007]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventor has found that the glass transition point between the paper substrate substantially consisting of cellulose fibers and the dye receiving layer is-. It has been found that the above problem can be solved by providing an intermediate layer containing a resin at 50 ° C. to 25 ° C., and the present invention has been completed.

[0008] The thermal transfer receiving sheet of the present invention comprises a support,
At least one surface thereof has a dye receiving layer provided with an intermediate layer interposed therebetween, and the intermediate layer contains a resin having a glass transition point of -50 ° C to 25 ° C. The intermediate layer preferably contains an acrylic resin, a vinyl acetate-ethylene copolymer resin or an ethylene-vinyl chloride copolymer resin as a main component. Further, it is preferable in terms of cost that the support contains paper.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the receiving sheet of the present invention, various papers, films, synthetic papers and the like can be used as a support, but commercially available coated papers, art papers, cast papers, uncoated papers and the like are preferable. Various papers using cellulose pulp are used as a support. Particularly, in the case of uncoated paper such as high quality paper, there is an advantage that the effects of the present invention are remarkably exhibited and the cost is low.

In the receiving sheet of the present invention, the glass transition point of the resin used for forming the intermediate layer is from -50.degree.
It is in the range of 5 ° C, preferably in the range of -50 ° C or more and less than 0 ° C. A resin having an acrylic resin, a vinyl acetate-ethylene copolymer resin or an ethylene-vinyl chloride copolymer resin as a main component is preferably selected within the range of the glass transition point.

The acrylic resin includes a poly (meth) acrylic acid alkyl ester, and the alkyl generally includes a linear alkyl, a branched alkyl, a cyclic alkyl and the like. For example, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, methacrylates such as n-amyl methacrylate, and methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate,
An acrylic resin having a desired glass transition point (Tg) can be obtained by including a homopolymer and a copolymer of an acrylate such as n-amyl acrylate and appropriately adjusting the monomer composition.

By setting the Tg of the intermediate layer to such a low value, it is possible to improve the image quality of printing mainly with a thermal transfer printer. This is because the heat from the printing head of the thermal transfer printer softens the receiving sheet and makes the contact with the head uniform.

However, when the Tg of the intermediate layer is lower than -50 ° C., the resin of the intermediate layer exudes from the edge of the receiving sheet and becomes sticky, which is not preferable.

If necessary, resins selected from polyester resins, polyurethane resins and the like may be added to the intermediate layer. It is preferable that no inorganic pigments and organic pigments are contained. Inorganic pigments such as heavy calcium carbonate, light calcium carbonate, talc, clay, natural or synthetic silicates, plastic pigments and the like can be added as long as the effects of the present invention are not impaired. The thickness of the intermediate layer is preferably adjusted to 1 μm or more, more preferably in the range of about 3 to 70 μm.

The composition of the receptor layer provided on the intermediate layer is not particularly limited, but generally a thermoplastic resin having an effective dyeing ability for a sublimable dye is preferably used.

Examples of the thermoplastic resin include polymers and copolymers of vinyl monomers such as styrene, vinyltoluene, acrylate, methacrylate, acrylonitrile, vinyl chloride, and vinyl acetate; polyesters, polyamides, polycarbonates, and the like. Condensed polymers such as polysulfone, epoxy resin and polyurethane;
Alternatively, a cellulose-based resin such as cellulose acetate butyrate may be used.

These thermoplastic resins may be used alone, or two or more resins having different properties may be used in combination. Further, if necessary, methyl cellulose, ethyl cellulose, as long as the desired effect of the present invention is not impaired,
Hydroxypropyl cellulose, starch, polyvinyl alcohol, polyamide resin, phenol resin, melamine resin, urea resin, urethane resin, epoxy resin, may contain other resin materials such as silicone resin, polyvalent isocyanate compound, epoxy compound, It is also possible to modify the receiving layer by adding a reactive compound such as an organometallic compound.

Further, the receiving layer is provided with a purpose of improving writability and the like.
For example, inorganic or organic pigments such as heavy calcium carbonate, light calcium carbonate, talc, clay, natural or synthetic silicic acid, titanium oxide, aluminum hydroxide, zinc oxide, and urea-formaldehyde resin powder, ultraviolet absorbers, and antioxidants ,
Various auxiliaries such as an antistatic agent, a release agent, and a lubricant can be appropriately added.

The coating amount of the receiving layer is appropriately selected according to the purpose of use of the receiving sheet and the like, but is generally preferably about ² to 15 g / m ² in terms of dry weight. On the receiving layer, for example, as disclosed in JP-A-59-165696 and JP-A-61-27290,
A thin heat-resistant release layer mainly composed of a silicone resin or the like having a property of transmitting a sublimation dye can be formed to prevent direct transfer of the dye or the dye layer from the color material transfer sheet.

The thermal transfer receiving sheet of the present invention thus obtained exhibits extremely excellent performance as a receiving sheet particularly when a sheet containing a heat sublimable dye is used as a color material transfer sheet. The heat sublimable dye referred to in the present invention does not cause a color material transition even when it comes into contact with a receiving sheet under normal handling conditions. However, for example, melting, evaporation, sublimation, dispersion, and the like only after heating at 60 ° C. or higher. Means a dye that causes color material transition, such as azo, nitro, anthraquinone, quinoline-based disperse dyes, triphenylmethane-based, fluoran-based basic dyes, oil-soluble It is used by appropriately selecting from various dyes such as dyes.

Further, the receiving sheet for thermal transfer of the present invention is not limited to a thermal recording system in which a heating plate such as a thermal printing unit or the like and a thermal head are used for contact heating, but also an energy radiation such as an infrared lamp, a solid laser or a gas laser. It is also useful for thermal recording by a non-contact heating method.

Each coating layer in the present invention comprises a blade coater, an air knife coater, a gate roll coater,
It can be formed by coating and drying using a known coater such as a gravure coater.

[0023]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which, of course, do not limit the technical scope of the present invention. Unless otherwise specified, “parts” and “%” in the examples represent “parts by weight” and “% by weight”, respectively.

Example 1 A water-based acrylic emulsion (trade name: Nicazole RX-87) was coated on the surface of a support (high-quality paper of 180 g / m ^{2 in} rice tsubo).
8A, manufactured by Nippon Carbide Industrial Co., Ltd., Tg = −46 ° C.) using an applicator bar to obtain a coating amount of 15 g / m 2 after drying.
^The composition was coated so as to be ^2, and dried to form an intermediate layer. A methyl ethyl ketone solution of a vinyl chloride-vinyl acetate copolymer resin (trade name: Solvain CN, manufactured by Nissin Chemical Co., Ltd.) was further applied thereon by using an applicator bar, and the coating amount after drying was 5%.
g / m ² and dried to form a receptor layer to produce a receptor sheet.

Example 2 An intermediate layer was formed of an aqueous acrylic emulsion (trade name: Nicazole RX-78B, manufactured by Nippon Carbide Industrial Co., Ltd., Tg = -14).
C)), except that the receiving sheet was formed in the same manner as in Example 1 except that the receiving sheet was formed.

COMPARATIVE EXAMPLE 1 An intermediate layer was prepared by using an aqueous acrylic emulsion (trade name: Nicazole RX-210, manufactured by Nippon Carbide Industries, Tg = -54)
C)), except that the receiving sheet was formed in the same manner as in Example 1 except that the receiving sheet was formed.

COMPARATIVE EXAMPLE 2 The intermediate layer was made of an aqueous acrylic emulsion (trade name: Nicazole RX-962B, manufactured by Nippon Carbide Industries, Tg = + 3).
0 ° C.), except that it was formed using Example 1.
A receiving sheet was produced in the same manner as described above.

Example 3 The intermediate layer was formed of an aqueous vinyl acetate-ethylene emulsion (trade name: Sumikaflex-751, manufactured by Sumitomo Chemical Co., Ltd., Tg).
= −15 ° C.), except that the receiving sheet was formed in the same manner as in Example 1.

Example 4 As an intermediate layer, an aqueous vinyl acetate-ethylene emulsion (trade name: Sumikaflex-500, manufactured by Sumitomo Chemical Co., Ltd.)
A receiving sheet was prepared in the same manner as in Example 1 except that the receiving sheet was formed using (Tg = 0 ° C.).

Example 5 An intermediate layer was formed from an ethylene-vinyl chloride emulsion (trade name:
Sumilite-1010, manufactured by Sumitomo Chemical Co., Ltd., Tg = 0
C)), except that the receiving sheet was formed in the same manner as in Example 1 except that the receiving sheet was formed.

[0031] Example 6 intermediate layer, ethylene - vinyl chloride emulsion (trademark:
Sumilite-1210, manufactured by Sumitomo Chemical Co., Ltd., Tg = + 2
0 ° C.), except that it was formed using Example 1.
A receiving sheet was produced in the same manner as described above.

COMPARATIVE EXAMPLE 3 An intermediate layer was prepared by using an aqueous vinyl acetate-ethylene emulsion (trade name: Sumilite-1320, manufactured by Sumitomo Chemical Co., Ltd., Tg =
(+ 30 ° C.), except that the receiving sheet was manufactured in the same manner as in Example 1.

Example 7 As a support, a biaxially stretched 150 μm-thick multilayer structure film containing a polyolefin as a main component and about 30% of calcium carbonate as an inorganic pigment (trade name: New Yupo FGS150, manufactured by YUPO Corporation) A receiving sheet was produced in the same manner as in Example 2 except that was used.

Comparative Example 4 A high-quality paper of 180 g / m ² was used as a support and no intermediate layer was provided on the surface thereof, and a vinyl chloride-vinyl acetate copolymer resin (trade name: Solvain CN, trade name) was directly used as a receiving layer. A methyl ethyl ketone solution (manufactured by Nissin Chemical Co., Ltd.) was applied using an applicator bar so that the coating amount after drying was 5 g / m ^2, and dried to prepare a receiving sheet.

[0035] on the surface of high-quality paper of Comparative Example 5 basis weight 75g / m ^2, polyurethane adhesive: (TM AD-593, manufactured by Toyo Morton Co., Ltd.),
A polymer resin layer having a thickness of 5 μm was provided. Next, a biaxially stretched 60 μm thick multilayer structure film (trade name: YUPO FGS60, manufactured by YUPO Corporation) containing a polyolefin as a main component and about 30% of calcium carbonate as an inorganic pigment was coated with the polymer resin layer. Lamination was performed on the upper surface by dry lamination with controlled tension so as to eliminate curling, to produce a laminated sheet having this surface as a surface. A methyl ethyl ketone solution of a vinyl chloride-vinyl acetate copolymer resin (trade name: Solvain CN, manufactured by Nissin Chemical Co., Ltd.) was applied on the surface of the laminated sheet using an applicator bar so that the coating amount after drying was 5 g / m ^2. , And dried to form a receptor layer, thereby producing a receptor sheet.

[Evaluation] The receiving sheets obtained in the above Examples and Comparative Examples were measured and evaluated by the following methods. Table 1 shows the obtained results.

[Image Uniformity] Each of three yellow, magenta, and cyan ink sheets provided with an ink layer containing a sublimable dye together with a binder on a 6 μm-thick polyester film was brought into contact with a receptor sheet to obtain a commercially available image. Using a thermal transfer video printer (trade name: UP-50, manufactured by Sony Corporation), a predetermined image is thermally transferred to a receiving sheet by stepwise heating with a thermal head, and a halftone single color and color superimposed image of each color is transferred. Printed. With respect to the recorded image transferred on the receiving sheet, the reflection density was measured for each applied energy using a Macbeth reflection densitometer RD-914 (trademark), and the optical density (black) was 0.15.
Regarding the uniformity of the recorded image of the gradation part corresponding to
Visual observation was made for (1) the presence or absence of shading, and (2) the presence or absence of white spots. The above-mentioned evaluation results are indicated by "O", the ordinary ones are indicated by "△", and those having defects are indicated by "X".

[Costs] The costs required to make the samples of the examples and comparative examples were estimated. Low-cost ones are indicated by ○, ordinary ones are indicated by Δ, and high-cost ones are indicated by X.

[Adhesive Resistance of Edge Surface] The sample of each Example and Comparative Example was cut from the surface (receptive layer surface) with a cutter knife, and the sticky resistance of the cross section was determined by touching with a hand. . Good without stickiness ○,
The normal ones were marked with △, and those with stickiness were marked with x.

[0040]

[Table 1]

[0041]

According to the present invention, a thermal transfer receiving sheet having good image quality, obtaining an image similar to a silver halide photograph, and having an advantage in cost can be put to practical use, greatly contributing to the industry. .

Claims (4)

[Claims] 1. A thermal transfer receiving sheet comprising a support and a dye receiving layer provided on at least one side of the support via an intermediate layer, wherein the intermediate layer has a glass transition point of −50 ° C. or more and 25 ° C. or less. A heat transfer receiving sheet comprising a resin having 2. The intermediate layer forming resin is an acrylic resin,
The thermal transfer receiving sheet according to claim 1, comprising at least one selected from an ethylene-vinyl acetate copolymer resin and an ethylene-vinyl chloride copolymer resin as a main component. 3. The method according to claim 1, wherein the resin for forming the intermediate layer is at -50 ° C. or higher.
The thermal transfer receiving sheet according to claim 1, having a glass transition point of less than about ° C. 4. The method according to claim 1, wherein said support comprises paper.
The thermal transfer receiving sheet as described in the above.