JP2832179B2 - Thermal transfer sheet - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a part requiring gradation, such as a photograph or a picture, and a floor, such as a character, a line, or an area to be painted in a single color. The present invention relates to a thermal transfer sheet that can be formed by transferring, by using the same thermal transfer sheet, a portion that does not require a tone but is required to be clear and high in density by a thermal transfer method. 2. Description of the Related Art A thermal transfer sheet in which a sublimable disperse dye is dispersed or dissolved in a binder is overlaid on paper or the like coated with a polyester resin, and is heated in a dot-like manner by a thermal head from the thermal transfer sheet side. (Hereinafter referred to as a sublimation transfer system) has been attempted. According to such a sublimation transfer system, the amount of dye transferred can be controlled in accordance with the density of the image. It is possible to form a toned image. However, according to the sublimation transfer system, although images with gradations such as photographs and paintings can be formed sufficiently, there is a drawback that characters and lines can be reproduced only insufficiently. This is because, in the sublimation transfer method, the amount of the dye to be transferred differs according to the density of the image, so that heat is also applied to the area around the area heated at the time of transfer, and fringes occur, and clear characters and lines are formed. This is because it is difficult to perform high-density transfer, and the amount of dye to be transferred is also limited. Further, in the sublimation transfer method, when a color that can be multiplied (for example, green can be multiplied by yellow and blue) is applied to a relatively large area, unevenness occurs in the amount of dye transferred. If it is, unevenness of the formed color is likely to occur. On the other hand, in the field of office equipment, a heat melting transfer system using a heat transfer sheet having a transfer layer in which a heat fusible binder such as wax is colored with carbon or the like is used. In the hot melt transfer method, the amount of the substance to be transferred is larger and higher uniform than when only the dye is transferred in the sublimation transfer method because the heat transfer layer of the portion that has been heated to the melting point or more is transferred together with the binder. Although there is an advantage that clear transfer can be performed with the density, it is not suitable for forming an image with gradation because it is basically a binary value of whether or not transfer is performed. Although various ideas have been devised for expressing the gradation by the hot-melt transfer method, at most, only a few steps of the gradation are reproduced in a stepwise manner. It is inherently difficult. Therefore, when it is necessary to simultaneously form an image with gradation and to form clear characters and lines with a high uniform density, such a conventional technique cannot cope with such a problem. For example, if you want to print a photographic image and text synthesized on a television screen on the same paper, print a magnetically recorded image and description of the image on the same paper, or print a proof print Such as when you want to print photos, characters, and line drawings that exist simultaneously on one page on the same paper, as in
In these cases, when either the sublimation transfer method or the hot melt transfer method was used, only an insufficient print was obtained, and the desired quality was not obtained. [0004] One of the problems to be solved in the present invention is that portions requiring gradation, such as photographs and paintings, and clarity and high density such as characters and lines are required. The required part is to eliminate the point that it was difficult to form simultaneously by either the sublimation transfer method or the hot melt transfer method, and 2 of the problems to be solved in the present invention are: An object of the present invention is to eliminate color unevenness that tends to occur due to unevenness in the amount of dye to be transferred when a color obtained by multiplication is applied to a relatively large area. [0005] In the present invention, a non-heat-transferable resin binder contains a dye which is transferred or melted or sublimated by heating to form a thermal transfer sheet.
In order to obtain a color gradation image, a first thermal transfer layer containing yellow, magenta, cyan, and black in a mixed range of 0.3 to 2.3 by weight of a dye / binder, A second transfer layer, which is colored with a binder that is melted and transferred by heating to obtain a toned image, on the same surface of the sheet substrate, and a polyvinyl butyral resin is formed on the other surface of the sheet substrate. The above problem can be solved by using a structure having a heat-resistant slip layer made of a reaction product of isocyanate and isocyanate. The present invention will be described below in detail with reference to the drawings. FIG. 1 shows a preferred embodiment of the thermal transfer sheet of the present invention. The thermal transfer sheet 1 has a yellow color (which means a color after being transferred to one side of a sheet-like base material 2). A sublimation transfer layer 3 of three colors, red (M) and blue (C), and a heat-meltable transfer layer 4 of black (Bk) are sequentially repeated. FIG.
By using the thermal transfer sheet 1 of the sublimation transfer layer 3
With the portion, a screen having a color gradation by a combination of three colors of yellow, red, and blue is obtained, and uniform black characters and lines with high density are obtained by the fusible transfer layer 4.
FIG. 2 shows an example of a thermal transfer sheet having a black (Bk) sublimation transfer layer in addition to the one shown in FIG. 1. By using this, a shadow image is appropriately emphasized and an image with gradation is obtained, and the fusible transfer layer 4 provides high density and uniformity as in the case of using the thermal transfer sheet of FIG. Black letters and lines are obtained. The reason why the heat-fusible transfer layer is a black (Bk) heat-fusible transfer layer in the examples of FIGS. 1 and 2 is that characters and lines are usually expressed in black in many cases. If you want to express in a color other than black,
Of course, other colors may be used. FIG. 3 shows a thermal transfer sheet having a sublimable transfer layer of four colors and a heat-meltable transfer layer of black (Bk) and green (Gr) as a special color repeatedly. By using this thermal transfer sheet, FIG.
As shown in (1), first, an image 11 having a gradation is formed by a portion of the sublimation transfer layer 3 so that the periphery thereof has a square shape, and a green (Gr) heat-meltable transfer layer is formed around the image 11. The frame 13 is formed by using the heat-fusible transfer layer of black (Bk), and characters and lines can be printed 12 outside the frame. In the thermal transfer sheet of the present invention, the sublimation transfer layer usually has three colors of yellow (Y), red (M), and blue (C) or, if necessary, black (Bk). It is recommended to have a sublimation transfer layer of four additional colors, but the number of colors is not limited to three or four, and may be five or more with special colors, or one or more. 2
It may be a color. In the thermal transfer sheet of the present invention, the heat-fusible transfer layer is usually black (B
k) Only one color is sufficient for expressing characters and lines,
Although only one color of black (Bk) is sufficient for expressing characters and lines, black (Bk) may be provided in place of a special color.
Both black and special colors may be provided. The number of spot colors can be increased if desired. Alternatively, the heat-fusible transfer layer may be a three-color heat-fusible transfer layer obtained by adding three colors of yellow (Y), red (M), and blue (C) or further added with black (Bk). Alternatively, a special color may be added to the four colors. In the thermal transfer sheet of the present invention, the order in which the sublimable transfer layer and the heat-meltable transfer layer are provided in each type may be determined mainly in accordance with the order of transfer, and the sublimable transfer layer may be composed of a plurality of colors. In this case, the heat-fusible transfer layers may be arranged between the sublimable transfer layers. In order to avoid trouble when successively transferring each color in a superimposed manner, it is preferable to arrange them in order from the one having the largest heat energy required for the transfer. As a result, the thermal transfer sheet of the present invention is shown in FIGS.
Without being limited to the example, by providing both types of thermal transfer layers, a sublimable transfer layer and a heat-fusible transfer layer, on the same thermal transfer sheet, the characteristics of each type of thermal transfer layer can be improved. This makes it possible to make effective use of the transfer, and it is possible to arbitrarily determine the color of the thermal transfer layer of each type. The materials for forming each part of the thermal transfer sheet and the method of manufacturing the thermal transfer sheet according to the present invention are described below. (Sheet-like base material) As the sheet-like base material 2 in the present invention, as a plastic film, polyester, polypropylene, cellophane, polycarbonate, cellulose acetate, polyethylene, polyvinyl chloride,
Polystyrene, nylon (polyamide), aromatic polyamide (aramid), polyimide, polysulfone, polyvinylidene chloride, polyvinyl alcohol, fluororesin,
Hydrochloric acid rubber, ionomers, etc., and papers such as condenser paper, paraffin paper, and other nonwoven fabrics can be used. Among these, a plastic film is preferable because it has a smooth surface and high mechanical strength. Among them, a polyester film and an aramid film are preferably used. The thickness of the sheet-like substrate is 2 to
It is 50 μm, preferably 2 to 12 μm. (Sublimation Transfer Layer) The sublimation transfer layer 3 contains a dye which transfers by melting or sublimation by heating in a non-thermal transferable binder. The dye is preferably a sublimable disperse dye, a sublimable oil-soluble dye, or a sublimable basic dye, and has a molecular weight of 150 to 80.
0, preferably 350-700. As a dye,
In addition to those that undergo transition by sublimation, those that undergo melting and transition by heating can also be used. These dyes are selected in consideration of the sublimation temperature, hue, weather resistance, solubility in the ink or the binder resin, and the like. C. I. (Abbreviation of Chemical Index, the same applies hereinafter) Disperse Yellow 51, 3, 5
4, 79, 60, 23, 7, 141, C.I.
I. Disperse Blue 24, 56, 14, 14
1, 334, 165, 19, 72, 87, 287, 154, 26, C.I. I. Disperse thread 135, 146, 59, 1, 73, 60
167, C.I. I. Disperse Violet 4, 1
3, 36, 56, 31, C.I. I. Solvent Violet 13, C.I. I. Solvent Black 3, C.I.
I. Solvent Green 3, C.I. I. Solvent Yellow 56, 14, 14, 16, 29, C.I. I. Solvent Blue 70, 35, 63, 36, 50, 4
9, 111, 105, 97, 11, C.I. I. Solvent Red 135, 81, 18, 25, 1
9, 23, 24, 143, 146, 182.
As the binder of the thermal transfer layer, a binder which does not transfer itself even when the amount of heat necessary for transferring the dye is given. For example, ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxy cellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate, cellulose resins such as cellulose acetate butyrate, polyvinyl alcohol, polyvinyl butyral, polyvinyl pyrrolidone,
Vinyl resins such as polyester, polyvinyl acetate and polyacrylamide can be used. As an example of a more preferable binder, instead of the usual polyvinyl butyral resin described above, the molecular weight is 60,000 to 200,000, and the weight% of the vinyl alcohol portion is 10 to 40%, preferably 15 to 30% in the polyvinyl butyral resin. Glass transition point of 60 ° C to 110 ° C, preferably 70 ° C to 110 ° C
Special polyvinyl butyral resin. If the molecular weight is less than 60,000, the binding power as a binder is insufficient, and if it exceeds 200,000, the viscosity at the time of application becomes too high, which hinders application. If the vinyl alcohol content is less than 10%, the stability over time of the thermal transfer layer is insufficient, so that aggregation, precipitation and bleeding of the surface of the dye cannot be avoided. Conversely, if it exceeds 40%, the sublimation of the dye is hindered due to the affinity of the polyvinyl alcohol portion for the dye, and the print density is reduced. The weight ratio of the dye to the binder in the thermal transfer layer was such that the dye / binder was 0.1.
Desirably, it is 3 or more, and if it is less than 0.3, the print density and the thermal sensitivity are insufficient. Further, the retention of the dye having a dye / binder ratio exceeding 2.3 in the binder is insufficient, and the storage stability of the thermal transfer sheet is reduced. Therefore, the dye / binder content is preferably 0.3 to 2.3, more preferably 0.55 to 1.5. It is desirable that the dye is dissolved in the binder of the thermal transfer layer.
In the conventional sublimation transfer paper for fabric, since the dye is dispersed in the binder, it is necessary to strike and give energy to the interaction between the dye molecules, and as a result, a high energy is required. The sensitivity decreases. In this regard, the fact that the dye is dissolved in the binder is advantageous in terms of heat sensitivity. The dye and the binder are kneaded with a solvent so as to have a predetermined ratio, desirably dissolved in the solvent to form an ink composition, and printed or coated on a sheet-like substrate by a known printing method or coating method. It is formed. (Heat-fusible transfer layer) The heat-fusible transfer layer 4
It consists of a binder and a colorant that melt when heated. As the binder, wax, drying oil, resin, mineral oil, derivatives of cellulose and rubber, and a mixture thereof are used. As the wax for the binder, microcrystalline wax, carnauba wax, and paraffin wax are preferably used. In addition, Fischer-Tropsch wax, various low molecular weight polyethylenes and some modified waxes, fatty acid esters, amides, wood wax, beeswax. Various waxes can be used, such as whale wax, wart wax, wool wax, shellac wax, candelilla wax and petrolatum.
Examples of the binder resin include EVA, EEA,
Polyethylene, polypropylene, polybutene, petroleum resin, vinyl chloride resin, polyvinyl alcohol, vinylidene chloride resin, methacrylic resin, polyamide, polycarbonate, fluororesin, polyvinyl formal, polyvinyl butyral, acetylcellulose, nitrocellulose, vinyl acetate resin, polyisobutylene, Alternatively, polyacetal or the like can be used. As a coloring agent,
Of the organic or inorganic pigments or dyes, those having good properties as a recording material, for example, those having a sufficient coloring density and not discoloring by light, heat and temperature are preferable. Since the colorant is used for coloring the binder of the heat-fusible transfer layer, those which melt or sublime by heating are not preferred. The hot-melt transfer layer is made into a hot-melt ink by a method such as melting and mixing the above-mentioned binder and colorant, and in addition to hot-melt coating on a sheet-like substrate, a normal printing or coating method, specifically Can be applied by a method such as hot lacquer coating, gravure coating, gravure reverse coating, roll coating, gravure printing, or bar coating, and the thickness is usually 0.1 to 30 μm, preferably 1 to 20 μm.
μ. (Other Configurations) To prevent sticking due to the heat of the thermal head when printing from the back side and to improve the slip, the thermal transfer sheet is treated on the side of the sheet-shaped substrate on which the thermal transfer layer is not provided. It is better to apply. For example, it is preferable to provide a heat-resistant slip layer mainly composed of a reaction product of a polyvinyl butyral resin and an isocyanate, an alkali metal salt or an alkaline earth metal salt of a phosphoric acid ester, and a filler. Polyvinyl butyral resin has a molecular weight of 60,000 to 200,000.
Having a glass transition point of 60 to 110 ° C.,
Further, from the viewpoint that there are many reaction sites with the isocyanate, those having a vinyl alcohol portion of 15 to 40% by weight are preferred. As an alkali metal salt or an alkaline earth metal salt of a phosphoric acid ester, Gafa RD720 manufactured by Toho Chemical Co., Ltd. is used.
0% by weight, preferably about 10 to 40% by weight is used. The heat-resistant slip layer is desirably accompanied by a heat-resistant layer as a lower layer, and a combination of a synthetic resin and a curing agent that can be cured by heating, for example, polyvinyl butyral and polyvalent isocyanate, acrylic polyol and polyvalent isocyanate, cellulose acetate and titanium chelate. An agent or a combination of a polyester and an organic titanium compound may be provided by coating. The thermal transfer sheet also allows the thermal printer to detect the boundary between the sublimable transfer layer and the heat-fusible transfer layer, the boundary between each color in the same type of thermal transfer layer, or each color. For the purpose, it is preferable to provide a mark that can be detected by an optical, magnetic, or electrical method using light such as visible light, ultraviolet light, or infrared light at an end of the sheet-like substrate or between the transfer layers. . (Usage of Thermal Transfer Sheet) The thermal transfer sheet of the present invention is superimposed on an image receiving sheet in which a polyester resin or the like is applied to synthetic paper or the like, as in the case of using a thermal transfer sheet having only a sublimable transfer layer. By using a thermal head from the back side of the thermal transfer sheet and applying thermal energy according to image information such as images or characters or lines, an image on the resin-coated surface of the image receiving paper and characters and / or lines are formed. be able to. For example, for an image or a line, an output signal of a color scanner (color separation machine) used in printing plate making is used. For text, a color scanner may be used, but preferably the output signal of a phototypesetter is used. Signals relating to two or more types of information of these different types may be output individually to the thermal printer, or may be output after combining both as necessary. In addition, by using a layout scanner, it is possible to use an output signal related to aggregate information in which information such as images, lines, and characters are aggregated. As a thermal head of the printer, only a thermal head for a sublimation transfer sheet is used.However, when transferring a heat-fusible transfer layer, printing may be performed with a constant applied energy, or for sublimation transfer. A thermal head and a thermal head for hot-melt transfer may be prepared, and heat may be applied to the sublimable transfer layer and the hot-melt transfer layer from separate heads.
When using separate thermal heads, use a higher resolution head than the sublimation transfer sheet thermal head for the hot-melt transfer sheet, compared to using only the sublimation transfer thermal head. You can also improve the quality of letters and lines. The thermal transfer sheet of the present invention has different types of transfer layers, such as a sublimable transfer layer and a hot-melt transfer layer, so that the transfer of a dye image according to the amount of heat applied. A gradation image can be formed using a sublimable transfer layer that can change the amount, and a high-density and clear character can be formed by a heat-fusible transfer layer that can transfer a colored binder only after obtaining a certain amount of heat. And lines can be formed. Further, in some cases, a solid portion of a special color having a constant hue and concealment properties can be formed, so that an image and a recorded matter (hard copy) having both characters and / or lines exhibited good quality, respectively. Can be obtained in a state. Further, when the dye / binder of the sublimable transfer layer is in the mixed range of 0.3 to 2.3, a transfer sheet having a high print density of a dye image, high thermal sensitivity in printing, and good storage stability can be obtained. Obtainable. In addition, yellow,
By using black in addition to magenta and cyan
The shadow part is emphasized moderately, and the gradation reproducibility is higher.
And a higher quality color gradation image can be obtained. Therefore, when you want to form a photo or text on the same sheet of paper, such as when creating a postcard, the gradation of the photo or text can be sufficiently reproduced and the text can be clearly formed. When the sublimation transfer method is used, there is an advantage that a print very similar to actual printing can be obtained.

[Brief description of the drawings] FIG. 1 is a cross-sectional view of a thermal transfer sheet of the present invention. FIG. 2 is a cross-sectional view of the thermal transfer sheet of the present invention. FIG. 3 is a cross-sectional view of the thermal transfer sheet of the present invention. FIG. 4 is a plan view showing an example of transfer. [Explanation of symbols] 1 Thermal transfer sheet 2 Sheet-shaped substrate 3 Sublimation transfer layer 4 Heat-meltable transfer layer

Claims (1)

(57) [Claims] A non-heat-transferable resin binder contains a dye which is transferred by melting or sublimation by heating, and a dye / binder is used in a weight ratio of 0.3 to 3 to obtain a color gradation image.
In the mixing range of 2.3, yellow, magenta, cyan,
A first thermal transfer layer containing black and a second transfer layer in which a binder that is melted and transferred by heating to obtain a monochrome non-tone image is colored on the same surface of the sheet substrate. And the other side of the sheet substrate
From the reaction product of rubutyral resin and isocyanate
A thermal transfer sheet having a heat-resistant slip layer .