JPH09183273A - Thermal transfer receptive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the waterproofness of a rear coated layer and prevent a blocking phenomenon from occurring even at the time of preservation under high temperature conditions by adding a styrene-maleate copolymer ammonium salt to the rear coated layer. SOLUTION: This thermal transfer receptive sheet consists of a sheet-like support, an image receptive layer for receiving a dye formed on one of the surfaces of the sheet-like support, and a rear coating layer formed on the other surface of the rear coated layer. The rear coated layer is composed mainly of an adhesive which is a styrene-maleate copolymer ammonium salt. In this case, the ammonium salt of the styrene-maleate copolymer ammonium salt contained as an adhesive in broken by thermal drying process after the adhesive is applied to the sheet-like support, and thus the waterproofness of the coated layer is improved. In addition, the styrene-maleate copolymer ammonium salt has adequately high glass transition temperatures, so that the sheet is free from a blocking phenomenon due to the surface fusion of the image receptive layer and the rear coated layer even at the time of preserving the sheet under high temperature conditions.

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 (hereinafter referred to as a receiving sheet). More specifically, the present invention relates to a receiving sheet in which the back coating layer has good water resistance and which does not cause blocking even during storage at high temperature and has excellent recording image quality.

[0002]

2. Description of the Related Art In recent years, development of a color hard copy of a thermal transfer system, especially a sublimation type thermal transfer printer has been advanced.
In a sublimation thermal transfer printer, an ink ribbon containing a sublimable dye layer of three colors (yellow, magenta, cyan) or four colors (yellow, magenta, cyan, black) is used.
It is possible to transfer and form a full-color image of density gradation by sequentially controlling and heating the heating energy of the thermal head to change the transfer amount of the dye of each color. Such thermal transfer printers are rapidly becoming popular in general households for applications such as printing a television image or an image taken by a video camera on a postcard or a sticker.

In general, such a printer has a mechanism in which a plurality of cut receiving sheets are mounted in a tray and are fed from the tray into the printer. The performance required for the back coating layer of the receiving sheet is (1) prevention of running defects due to static electricity, (2) prevention of suction of dust and dust due to static electricity, (3) reduction of friction coefficient between receiving sheets, (Four)
For example, various chemicals such as antistatic agents, slip agents, and pigments are added to the back surface coating layer for imparting writability. Up to now, the receiving sheets rub against each other at the time of paper feeding, and they are charged by rubbing against mechanical parts such as rolls while running in the printer, and the receiving sheets stick to each other due to electrostatic attraction, and the receiving sheets do not collect dust. It has been reported that an antistatic treatment is applied to the back surface of the receiving sheet in order to solve the problem that the ink is sucked and partially not printed (printing omission) (Japanese Patent Publication No. 6-41231). According to this report, it is most preferable to apply a conductive coating material containing a conductive substance to the back surface of the receiving sheet to form the conductive layer as a back surface coating layer. The conductive paint is prepared by dissolving or dispersing an antistatic agent or an electronically conductive inorganic fine powder in a binder resin, and the binder resin is a polyacrylic acid ester resin or a polyurethane resin. Examples of the synthetic resin emulsion, synthetic rubber latex such as styrene-butadiene, polyvinyl alcohol resin, and water-soluble resin such as starch.

However, when a synthetic resin emulsion such as a polyacrylic acid ester resin or a polyurethane resin is used as a binder resin, since the synthetic resin emulsion generally has a low glass transition temperature, the receiving sheets are stacked in a high temperature environment. When stored, blocking may occur, causing problems such as poor running, poor image quality, and poor appearance. Similarly, when a synthetic rubber latex such as styrene-butadiene is used as a binder resin, the synthetic rubber latex also has a low glass transition temperature, so that it blocks when stored in a stacked state in a high temperature environment. It is possible that various problems will occur. on the other hand,
When a water-soluble resin such as polyvinyl alcohol resin or starch is used as the binder resin, the water resistance is poor, so if water droplets get on the backside coating layer in a high humidity environment, the backside coating layer will dissolve, resulting in poor performance or poor appearance. There is a problem of affecting. No back coating layer has completely solved the blocking and water resistance during high temperature storage.

Further, a method of improving water resistance by using a binder resin of acetoacetylated polyvinyl alcohol and a compound capable of reacting with an acetyl group has been attempted (JP-A-7-137463), This method has a problem that not only the water resistance is insufficient, but also a compound capable of reacting with an acetyl group is discolored over time, resulting in poor appearance.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a receiving sheet which has a back coating layer having good water resistance and which is free from blocking even when stored at high temperature and has excellent recording image quality.

[0007]

The thermal transfer receiving sheet of the present invention comprises a sheet-like support, an image receiving layer for receiving a dye formed on one surface of the sheet-like support, and the sheet-like support. In the thermal transfer receiving sheet having the back surface coating layer formed on the other surface of the above, the back surface coating layer contains the styrene-maleic acid copolymer ammonium salt as an adhesive.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION As a result of intensive studies to achieve the above object, in a thermal transfer receiving sheet having a back coating layer containing an adhesive as a main component, a styrene-maleic acid copolymer was used as the adhesive component. The present inventors have completed the present invention by discovering that the inclusion of the polymer ammonium salt has a remarkable effect in improving the water resistance of the backside coating layer and preventing blocking during high temperature storage.

The ammonium salt of the styrene-maleic acid copolymer in the present invention is one in which the structure of the ammonium salt is destroyed by heating and becomes insoluble in water. Therefore, when it is used for the back surface coating layer of the present invention, the ammonium salt of the styrene-maleic acid copolymer ammonium salt contained as an adhesive is included by being dried by heating after being applied to the sheet-shaped support. The structure is destroyed and the water resistance of the coating layer is improved. Further, the styrene-maleic acid copolymer ammonium salt used in the present invention has a glass transition temperature of about 100 ° C., and it is an adhesive (acrylic resin, acrylic emulsion, butadiene copolymer) conventionally used for the back coating layer. It is sufficiently higher than the glass transition temperature of (polymer latex, etc.) and does not cause blocking of the receiving sheet due to fusion of the surface of the receiving layer and the surface of the back coating layer even when stored at high temperature, resulting in poor running, deterioration of image quality, There is no appearance defect. Specific examples of the styrene-maleic acid copolymer ammonium salt include polymalon 1318 manufactured by Arakawa Chemical Industry.

The back coating layer of the present invention contains an adhesive as a main component, and uses a styrene-maleic acid copolymer ammonium salt as an adhesive component, within a range that does not impair the effects of the present invention. Then, for example, another adhesive may be used in combination for the purpose of enhancing the adhesiveness between the back surface coating layer and the sheet-shaped support. As such an adhesive, an acrylic resin,
Examples thereof include acrylic emulsion and butadiene copolymer latex. When the styrene-maleic acid copolymer ammonium salt is used in combination with other adhesives, in order to obtain the sufficient effect of the present invention, the ratio of the styrene-maleic acid copolymer ammonium salt used is such that the back coating It is preferably 20% by weight or more of the total adhesive component of the layer, and 30
-100% by weight is more preferred. Below 20% by weight,
The effects of improving the water resistance and preventing blocking of the receiving sheet during storage at high temperature are not sufficiently exhibited.

The back coating layer of the present invention contains an antistatic agent or an electronically conductive inorganic powder. As the antistatic agent, commercially available anionic and nonionic antistatic agents can be used, and as the electronically conductive inorganic fine powder, fine powder such as titanium oxide or zinc oxide is mixed with impurities and baked, It is possible to use a material having enhanced electronic conductivity. Further, if necessary, an adhesive cross-linking agent, a slip agent, a pigment, and a colored dye may be added. Commercially available wax, silicone resin or the like can be used as the slip agent, and silica pigment, clay, titanium oxide, calcium carbonate, barium sulfate or the like can be used as the pigment. The coating amount of the back surface coating layer is not particularly limited, but 0.1 to 10 g / m
A range of ² is suitable. If the amount is too small, the sufficient effect is not exhibited, and if the amount is too large, no further effect can be expected, and the cost is increased, which is not practical.

Examples of the sheet-like support used in the present invention include paper base materials such as coated paper, art paper, and fine paper, and laminated paper obtained by laminating a resin such as polyethylene on a paper base material.
Examples thereof include a film of polyester, nylon, or polyolefin (for example, polypropylene), or a biaxially stretched film having voids and a multilayer structure containing a polyolefin resin and an inorganic pigment as main components. Furthermore, not only the above-mentioned materials can be used alone, but also those in which two or more kinds of the above-mentioned materials are laminated by a dry lamination method can be used, and the combination thereof is not limited.

The thickness of the sheet-like support is 100 to 300 μm.
m is preferred. When the thickness is 100 μm or less, the mechanical strength is insufficient, and the rigidity and repulsion force of the melt-receiving sheet obtained therefrom are insufficient,
It is not possible to sufficiently prevent curling of the melt-receiving sheet during printing. On the other hand, if it exceeds 300 μm, the thickness of the melt receiving sheet obtained becomes excessive. In a printer with a predetermined volume, there is a limit to the capacity of the melt-receiving sheet, and an increase in thickness may lead to a decrease in the number of melt-receiving sheets that can be accommodated, or increase the printer volume, making it difficult to make the printer compact. .

In the receiving sheet of the present invention, the dye receiving layer provided on one surface of the sheet-like support is mainly composed of a dyeing resin capable of dyeing the sublimable dye transferred from the ink ribbon. It Examples of such dyeable resins include polyester resins, vinyl chloride-vinyl acetate copolymer resins, polycarbonate resins, acrylic resins, cellulose derivatives and the like. The coating amount of the image receiving layer is 1
It is preferably ˜12 g / m ² , and more preferably 3 to 10 g / m ² . If the image receiving layer is less than 1 g / m ² , defects such as deterioration of the image and deterioration of gloss on the printed surface may occur. In addition, the image receiving layer is 12
If it exceeds g / m ² , not only is the effect saturated and uneconomical, but the print density may decrease.

In the image-receiving layer of the receiving sheet of the present invention, a crosslinking agent, a slipping agent, a releasing agent, etc. may be added, if necessary, for the purpose of preventing fusion with the ink ribbon due to heating of the thermal head during printing. It is preferably added. Also, if necessary, a fluorescent dye, a plasticizer, an antioxidant, or
You may add a pigment, an ultraviolet absorber, etc. These additives may be mixed with the main component of the receptor layer and coated, or may be coated as a separate coating layer on and / or below the receptor layer. As the pigment, silica pigment, titanium pigment, clay, plastic pigment, or the like can be used. Among them, silica pigments are preferably used in terms of whiteness and image quality, and the average particle size thereof is 1 to 1.
About 2 μm is desirable, and about 2 to 15 parts by weight is suitable for 100 parts by weight of the dyeable resin.

When the receiving sheet runs in the printer, in order to prevent running troubles due to static electricity,
An antistatic agent layer different from the back coating layer can be coated on the receiving layer surface of the receiving sheet or between the receiving layer and the sheet-shaped support. The receiving layer and the back coating layer and other coating layers of the receiving sheet of the present invention can be formed by coating with a coater such as a bar coater, a gravure coater, a comma coater, a blade coater, an air knife coater, and drying. .

[0017]

The present invention will be described in detail with reference to the following examples, but the scope of the present invention is not limited thereto.
In the examples, "%" and "parts" all indicate "% by weight" and "parts by weight" unless otherwise specified. Example 1 Polyethylene terephthalate (PET) having a thickness of 50 μm
On the front and back of the film, a biaxially stretched multi-layered film (trade name: YUPO FPG60, manufactured by Oji Yuka Synthetic Paper), which is mainly composed of an inorganic pigment and polyolefin and has a thickness of 60 μm, is dry laminated by using a polyester adhesive. Then, the sheet-like support was laminated. On one surface thereof, a coating material 1 having the following composition and having a solid content of 8 g / m 2 was formed to form an image receiving layer.
^It was coated by the die coating method at a ratio of ² and dried.
On the other surface, a coating material 2-1 having the following composition was applied as a back surface coating layer by a bar coating method so that the solid content was 1 g / m ^2, and dried at 120 ° C. for 2 minutes to form a receiving sheet. It was made. Paint 1 Component Parts by weight saturated polyester resin (trademark: Byron 200, Toyobo Co., Ltd.) 100 parts Silicone resin (Trademark: SH3746, Toray Dow Corning Silicone Co.) 5 parts Toluene / methyl ethyl ketone = 5/1 mixed solvent 595 parts paint 2- 1 component parts by weight of styrene - maleic acid copolymer ammonium salt (glass transition temperature: 100 ° C., trademark: Polymaron 1318, Arakawa chemical Industries, Ltd.) 100 parts silicone resin (trademark: Symac US-450, manufactured by Toagosei) 10 Part Antistatic agent (trademark: Chemistat 6120, manufactured by Sanyo Kasei) 5 parts Silica pigment (trademark: P78-C, manufactured by Mizusawa Chemical Co., Ltd.) 10 parts Water 900 parts

Example 2 A receiving sheet was obtained in the same manner as in Example 1 except that the back coating layer was formed using the coating composition 2-2 having the following composition. Coating 2-2 Component Parts by weight of styrene - maleic acid copolymer ammonium salt (glass transition temperature: 100 ° C., trademark: Polymaron 1318, Arakawa Chemical Industries, Ltd.) 50 parts of acrylic emulsion (glass transition temperature: 10 ° C., trademark: A -106, manufactured by Toa Gosei Co., Ltd. 50 parts Silicone resin (trademark: Cymac US-450, manufactured by Toa Gosei Kagaku) 10 parts Antistatic agent (trademark: Chemistat 6120, manufactured by Sanyo Kasei) 5 parts Silica pigment (trademark: P78-C) , Manufactured by Mizusawa Chemical Co., Ltd. 10 parts Water 900 parts

Example 3 A receiving sheet was obtained in the same manner as in Example 1 except that the back coating layer was formed by using the coating composition 2-3 having the following composition. Coating 2-3 Component Parts by weight of styrene - maleic acid copolymer ammonium salt (glass transition temperature: 100 ° C., trademark: Polymaron 1318, Arakawa Chemical Industries, Ltd.) 35 parts Styrene - butadiene copolymer (glass transition temperature: -14 C, trademark: 0624, manufactured by Japan Synthetic Rubber) 65 parts Silicone resin (trademark: Cymac US-450, manufactured by Toagosei Kagaku) 10 parts Antistatic agent (trademark: Chemistat 6120, manufactured by Sanyo Kasei) 5 parts Silica pigment (trademark: P78-C, manufactured by Mizusawa Chemical Co., Ltd.) 10 parts Water 900 parts

Example 4 A receiving sheet was obtained in the same manner as in Example 1 except that the back coating layer was formed by using the coating composition 2-4 having the following composition. Coating 2-4 Component Parts by weight of styrene - maleic acid copolymer ammonium salt (glass transition temperature: 100 ° C., trademark: Polymaron 1318, Arakawa Chemical Industries, Ltd.) 25 parts of acrylic emulsion (glass transition temperature: 10 ° C., trademark: A -106, manufactured by Toa Gosei Co., Ltd. 75 parts Silicone resin (trademark: Cymac US-450, manufactured by Toa Gosei Co., Ltd.) 10 parts Antistatic agent (trademark: Chemistat 6120, manufactured by Sanyo Kasei) 5 parts Silica pigment (trademark: P78-C) , Manufactured by Mizusawa Chemical Co., Ltd. 10 parts Water 900 parts

Comparative Example 1 A receiving sheet was obtained in the same manner as in Example 1 except that the back coating layer was formed by using the coating composition 2-5 having the following composition. Coating 2-5 Component Parts by weight Acrylic emulsion (glass transition temperature: 10 ° C., trademark: A-106, Toagosei Co., Ltd.) 100 parts Silicone resin (Trademark: Symac US-450, manufactured by Toagosei) 10 parts Antistatic Agent (trademark: Chemistat 6120, manufactured by Sanyo Kasei) 5 parts Silica pigment (trademark: P78-C, manufactured by Mizusawa Chemical Co., Ltd.) 10 parts Water 900 parts

Comparative Example 2 A receiving sheet was obtained in the same manner as in Example 1 except that the back coating layer was formed by using the coating composition 2-6 having the following composition. Coating 2-6 Component Parts by weight styrene - butadiene copolymer (glass transition temperature: -14 ° C., trademark: 0624, by Japan Synthetic Rubber Co., Ltd.) 100 parts Silicone resin (Trademark: Symac US-450, Toagosei Co., Ltd.) 10 Part Antistatic agent (trademark: Chemistat 6120, manufactured by Sanyo Kasei) 5 parts Silica pigment (trademark: P78-C, manufactured by Mizusawa Chemical Co., Ltd.) 10 parts Water 900 parts

Comparative Example 3 A receiving sheet was obtained in the same manner as in Example 1 except that the back coating layer was formed using the coating composition 2-7 having the following composition. Paint 2-7 Component weight parts Acetoacetylated polyvinyl alcohol (trademark: Gocefimer Z-200, manufactured by Nippon Gosei) 100 parts Glyoxal 5 parts Silicone resin (trademark: Cymac US-450, manufactured by Toagosei Kagaku) 10 parts Charge Inhibitor (Trademark: Chemistat 6120, Sanyo Kasei) 5 parts Silica pigment (Trademark: P78-C, Mizusawa Chemical Co., Ltd.) 10 parts Water 900 parts

Evaluation Method The receiving sheets obtained in the above Examples and Comparative Examples were evaluated as follows, and the obtained results are shown in Table 1. (1) Evaluation of Water Resistance After dropping one drop of pure water on the back surface coating layer of the receiving sheet and leaving it for 30 minutes, the water droplets were wiped off with a dry cloth, and the back surface coating layer was visually evaluated according to the following evaluation criteria. [Water resistance evaluation criteria] A: The back coating layer is not melted at all. ◯: The back coating layer is slightly melted, but there is no problem in practical use. Δ: The back surface coating layer is melted and slightly peeled off, which is a problem in practical use. X: The back surface coating layer is melted and almost removed. (2) Discoloration test of backside coating layer The above-mentioned receiving sheet was allowed to stand at 60 ° C for 7 days, and the backside coating layer before and after the test was visually evaluated according to the following evaluation criteria. [Discoloration Test Evaluation Criteria] ○: No discoloration before and after the test. X: There is discoloration after the test.

(3) Print runnability and recording image quality 500 sheets of the above-mentioned receiving sheets are piled up so that the receiving layer surface and the back coating layer surface are overlapped, left for 48 hours in an environment of 60 ° C., and then the 25 sheets from the bottom are sublimated. Continuously print with a video printer (trademark: CVP-G7, made by Sony),
The runnability was evaluated according to the following evaluation criteria. [Runability evaluation criteria] ○: Runability is good. X: Poor running property occurred. Regarding the recording image quality, the fifth print sample from the bottom was selected, and the damage condition of the receiving layer due to blocking on the surface of the receiving layer and the surface of the back layer was visually evaluated according to the following evaluation criteria. The print images obtained in each example were clear and had sufficient recording density. [Image Quality Evaluation Criteria] ◯: No image of blocking and good image quality. ×: There is a blocking mark, and the image quality is poor. In the above evaluation criteria, a value of ◯ or higher is good and suitable for practical use, but a value of Δ or lower is insufficient and not suitable for practical use.

[0026]

[Table 1]

[0027]

INDUSTRIAL APPLICABILITY The thermal transfer receiving sheet of the present invention is a receiving sheet having good water resistance of the back coating layer and excellent recording image quality without blocking of the receiving sheet even at high temperature storage, and has high practical value. It is a thing.

Claims (1)

[Claims] 1. A sheet-shaped support, and an image-receiving layer for receiving a dye formed on one surface of the sheet-shaped support,
A thermal transfer receiving sheet having a back coating layer formed on the other surface of the sheet-like support, wherein the back coating layer contains a styrene-maleic acid copolymer ammonium salt as an adhesive. Thermal transfer receiving sheet.