JPH08295083A - Thermal transfer sheet - Google Patents

Abstract

PURPOSE: To provide a thermal transfer sheet that achieves high print density of dye image and has high thermal sensitivity in printing and good storability by setting specifically a range of dye-binder mixing ratio in a sublimation transfer layer. CONSTITUTION: A base sheet 2 supports on the same face a first thermal transfer layer 3 in which a dye that transfers when melted or sublimated by heating is contained in a non-thermal transferable resin binder and the dye/binder mixing ratio ranges from 0.3 to 2.3, and a second thermal transfer layer 4 containing a colored binder that transfers when melted by heating.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention does not require gradation such as a portion such as a photograph or painting that requires gradation, and a region such as a character, a line, or a solid color, but has clear and high density. The present invention relates to a thermal transfer sheet that can be formed by transferring the required part and the same thermal transfer sheet by a thermal transfer method.

[0002]

2. Description of the Related Art A thermal transfer sheet, in which a sublimable disperse dye is dispersed or dissolved in a binder, is placed on a polyester resin-coated paper, etc. A method (hereinafter, referred to as a sublimation transfer method) for forming an image has been attempted. According to such a sublimation transfer method, since the amount of the dye to be transferred can be controlled according to the density of the image, there is a gradation. It becomes possible to form an image. However, according to the sublimation transfer method, an image with gradation such as a photograph or a painting can be sufficiently formed, but there is a drawback that characters, lines and the like can be reproduced only insufficiently. This is because in the sublimation transfer method, the amount of dye transferred varies depending on the density of the image, so heat is also affected around the area that was heated during transfer, and fringes occur, forming clear characters and lines. This is because it is difficult to reproduce, and because the amount of dye transferred is limited, it is difficult to reproduce high density. Further, in the sublimation transfer method, when an attempt is made to apply a color produced by multiplication (for example, green is produced by multiplication of yellow and blue) to a relatively large area, the amount of dye transferred is uneven. If present, unevenness in the formed color is likely to occur.

On the other hand, a hot-melt transfer method using a heat-transfer sheet having a transfer layer in which a heat-meltable binder such as wax is colored with carbon has been used in the field of office equipment. In the thermal fusion transfer method, the portion of the thermal transfer layer that has been heated to a temperature higher than the melting point is transferred together with the binder. Although there is an advantage that clear transfer can be performed at a density, it is not suitable for forming an image with gradation because it is a binary value that is transferred or not transferred in principle. Although various measures have been taken to express gradation with the heat fusion transfer method, at most, gradations of several steps are reproduced step by step. It's inherently difficult. Therefore, in the case where it is necessary to simultaneously form an image having gradation and formation of clear characters and lines with high uniform density, such a conventional technique cannot deal with it. For example, if you want to print composited photo-tone images and characters on the same paper on a television screen, if you want to print magnetically recorded images and image descriptions on the same paper, or proof print This is the case when you want to print photographs, characters, and line drawings that exist on one page at the same time, such as
In these cases, when either the sublimation transfer method or the thermal fusion transfer method was used, insufficient print was obtained, and the desired quality could not be obtained.

[0004]

One of the problems to be solved in the present invention is that a part such as a photograph or a painting that requires gradation and a character or line that requires clarity and high density. It is to solve the problem that it was difficult to simultaneously form the part and the part by either the sublimation transfer method or the thermal fusion transfer method, and the second problem to be solved in the present invention is When trying to apply a possible color to a relatively large area, it is necessary to eliminate the color unevenness that is likely to occur due to the uneven amount of the dye to be transferred.

[0005]

In the present invention, the constitution of the thermal transfer sheet comprises a dye which is melted or sublimated by heating to be transferred in a non-heat transferable resin binder,
The first thermal transfer layer in which the dye / binder is in the mixed range of 0.3 to 2.3 and the second thermal transfer layer in which the binder that is melted and transferred by heating is colored are the same as the sheet-shaped substrate. The above-mentioned problems can be solved by adopting the structure provided on the surface.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings. FIG. 1 shows a preferred embodiment of the thermal transfer sheet of the present invention, in which the thermal transfer sheet 1 has a yellow color (meaning the color after being transferred, on one side of the sheet-shaped substrate 2; The same applies to the following in middle Y), red (M), blue (C) three-color sublimable transfer layer 3 and black (Bk) heat-meltable transfer layer 4 are sequentially repeated. Figure 1
By using the thermal transfer sheet 1 of
By the portion, a screen having a color gradation by crossing three colors of yellow, red and blue is obtained, and by the fusible transfer layer 4, high density and uniform black characters and lines are obtained.
FIG. 2 shows an example of a thermal transfer sheet having a black (Bk) sublimable transfer layer in addition to the one shown in FIG. When used, a shadow portion is appropriately emphasized and an image with gradation is obtained, and the fusible transfer layer 4 provides a high density and uniform image as in the case of using the thermal transfer sheet of FIG. Black letters and lines are obtained. The reason why the heat-melting transfer layer is black (Bk) in the examples of FIGS. 1 and 2 is that the characters and lines are usually expressed in black, and the characters and lines are 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 which has a sublimable transfer layer of four colors and a black (Bk) and a green (Gr) heat-meltable transfer layer as a special color which are repeatedly formed. By using this thermal transfer sheet, as shown in FIG.
As shown in FIG. 1, first, an image 11 having gradation is formed by the sublimable transfer layer 3 so that the periphery has a quadrangular shape, and a green (Gr) heat-melting transfer layer is formed around the image 11. It is possible to form the frame 13 by using it, and separately use a black (Bk) heat-meltable transfer layer to print characters or lines 12 on the outside of the frame.

In the thermal transfer sheet of the present invention, the sublimable transfer layer is usually composed of three colors of yellow (Y), red (M) and blue (C), or black (Bk) if necessary. Although it is recommended to have an additional sublimable transfer layer of 4 colors, the number of colors is not limited to 3 or 4 and may be 5 or more with special colors, or 1 or Two
It may be color. In the thermal transfer sheet of the present invention, the heat-meltable transfer layer is usually black (B
Only one color of k) is enough for expressing letters and lines,
Only one color of black (Bk) is sufficient for expressing characters and lines, but black (Bk) may be replaced by a special color.
Both black and special colors may be provided. The number of spot colors can be increased if desired. Alternatively, as the heat-melting transfer layer, three colors of yellow (Y), red (M), and blue (C) or black color (Bk) is added to obtain a four-color heat-melting transfer layer, or these three colors are used. Alternatively, special colors may be added to the four colors. In the thermal transfer sheet of the present invention, the order of providing each type of thermal transfer layer of the sublimable transfer layer and the heat-meltable transfer layer may be determined mainly according to the order of transfer, and the sublimable transfer layer is composed of a plurality of colors. In this case, the heat-meltable transfer layer may be arranged between the sublimable transfer layers. In order to avoid troubles when the respective colors are overlaid and sequentially transferred, it is preferable to arrange the colors in descending order of heat energy required for transfer. After all, the thermal transfer sheet of the present invention has the structure shown in FIGS.
However, the characteristics of each type of thermal transfer layer can be improved by providing both types of thermal transfer layers, a sublimable transfer layer and a heat-meltable transfer layer, on the same thermal transfer sheet. It is possible to make good use of the transfer, and the color of the thermal transfer layer of each mold can be arbitrarily determined.

Materials for forming each part of the thermal transfer sheet and a method for manufacturing the thermal transfer sheet according to the present invention will be described below.

(Sheet-like substrate) The sheet-like substrate 2 in the present invention is a plastic film such as 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 as papers, condenser paper, paraffin paper, or non-woven fabric can be used. Of these, a plastic film is preferable because it has a smooth surface and high mechanical strength, and among them, it is desirable to use a polyester film or an aramid film. The thickness of the sheet-shaped substrate is 2 to
The thickness is 50 μm, preferably 2 to 12 μm.

(Sublimable Transfer Layer) The sublimable transfer layer 3 contains a dye which is melted or sublimated by heating to be transferred, in a non-heat 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.
It is 0, preferably 350 to 700. As a dye,
In addition to sublimation and transformation, those that are melted and transformed by heating can be used. These dyes are selected in consideration of sublimation temperature, hue, weather resistance, solubility in ink or binder resin, and are, for example, as follows. C. I. (Abbreviation of chemical index, the same applies below) Disperse Yellow 51, 3 and 5
4, ibid 79, ibid 60, ibid 23, ibid 7, ibid 141, C.I.
I. Disperse Blue 24, 56, 14 and 30
1, 334, 165, 19, 19, 72, 87, 287, 154, 26, C.I. I. Disperse Thread 135, 146, 59, 1, 1, 73, 60,
167, C.I. I. Disperse Violet 4 and 1
3, the same 36, the same 56, the same 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, the same 14, the same 16, the same 29, C.I. I. Solvent Blue 70, 35, 63, 36, 50, 4
9, the same 111, the same 105, the same 97, the same 11, C.I. I. Solvent Red 135, 81, 18, 18, 25, 1
9, 23, 24, 143, 146, 182.
As the binder of the thermal transfer layer, a binder that does not transfer itself even if the heat amount necessary for transferring the dye is given. For example, ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxycellulose, 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 a more preferable example of the binder, not the usual polyvinyl butyral resin described above, but 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 is 60 ° C to 110 ° C, preferably 70 ° C to 110 ° C
The special polyvinyl butyral resin of When the molecular weight is less than 60,000, the binding strength as a binder is insufficient, and when it exceeds 200,000, the viscosity at the time of coating becomes too high, which hinders coating. If the vinyl alcohol portion is less than 10%, the thermal transfer layer will have insufficient stability over time, and therefore aggregation and precipitation of the dye and bleeding on the surface cannot be avoided. On the other hand, when it exceeds 40%, the sublimation of the dye is hindered due to the affinity of the polyvinyl alcohol portion for the dye, and the printing density is lowered. The weight ratio of the dye to the binder in the thermal transfer layer is such that the dye / binder is 0.
It is preferably 3 or more, and if it is less than 0.3, the print density and thermal sensitivity are insufficient. In addition, the retention of the dye / binder exceeding 2.3 in the binder is insufficient and the storage stability of the thermal transfer sheet is deteriorated. Therefore, the dye / binder is preferably 0.3 to 2.3, and more preferably 0.55 to 1.5. The dye is preferably 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 of the high energy inevitably, the heat The sensitivity decreases. In this respect, it is advantageous in terms of thermal sensitivity that the dye is dissolved in the binder. The dye and the binder are kneaded with a solvent so as to have a predetermined ratio, and are preferably dissolved in the solvent to form an ink composition, which is printed or coated on a sheet-shaped substrate by a known printing method or coating method. It is formed.

(Heat Melting Transfer Layer) The heat melting transfer layer 4 is
It consists of a binder and a colorant that melt when heated. As the binder, wax, drying oil, resin, mineral oil, cellulose and rubber derivatives, and the like, and mixtures thereof are used. As the wax of the binder, microcrystalline wax, carnauba wax and paraffin wax are preferably used. In addition to these, Fischer-Tropsch wax, various low molecular weight polyethylene and some modified waxes, fatty acid ester, amide, wood wax, beeswax Various waxes such as, whale wax, wart wax, wool wax, shellac wax, candelilla wax and petrolatum can be used.
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, acetyl cellulose, nitrocellulose, vinyl acetate resin, polyisobutylene, Alternatively, polyacetal or the like can be used. As a colorant,
Among organic or inorganic pigments or dyes, those having good characteristics as a recording material, for example, those having a sufficient coloring density and not discolored by light, heat or temperature are preferable. Since the colorant is used for the purpose of coloring the binder of the heat-meltable transfer layer, it is not preferable that the colorant melts or sublimes when heated. The heat-melt transfer layer is made into a heat-melt ink by a method such as melting and mixing the above binder and colorant, and hot-melt coating on a sheet-shaped substrate, as well as ordinary printing or coating method, Can be applied by a method such as hot lacquer coating, gravure coating, gravure reverse coating, roll coating, gravure printing and bar coating, and the thickness is usually 0.1 to 30 μm, preferably 1 to 20 μm.
is μ.

(Other Structures) The thermal transfer sheet is treated on the side of the sheet-shaped substrate on which the thermal transfer layer is not provided in order to prevent sticking due to the heat of the thermal head when printing from the back side and to improve sliding. Good to give. For example, it is preferable to provide a heat resistant slip layer mainly containing a reaction product of polyvinyl butyral resin and isocyanate, an alkali metal salt or alkaline earth metal salt of phosphoric acid ester, and a filler. The polyvinyl butyral resin has a molecular weight of 60,000 to 200,000.
A glass transition point of 60 to 110 ° C.,
From the viewpoint of many reaction sites with isocyanate, it is preferable that the weight% of the vinyl alcohol portion is 15 to 40%. As the alkali metal salt or alkaline earth metal salt of phosphoric acid ester, Gafac RD720 manufactured by Toho Kagaku Co., Ltd. is used, and is 1 to 5 with respect to polyvinyl butyral resin.
0% by weight, preferably about 10 to 40% by weight may be used. The heat-resistant slip layer is preferably accompanied by a heat-resistant layer as a lower layer, and a combination of a synthetic resin that can be cured by heating and a curing agent thereof, such as polyvinyl butyral and polyvalent isocyanate, acrylic polyol and polyvalent isocyanate, cellulose acetate and titanium chelate. An agent or a combination of polyester and an organic titanium compound may be provided by coating.

In the thermal transfer sheet, the thermal printer can detect the boundary between the sublimable transfer layer and the thermal melting transfer layer, the boundary of each color in the thermal transfer layer of the same type, 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 visible light, ultraviolet light, infrared light, or the like on the edge of the sheet-shaped substrate or between the transfer layers. .

(Method of Utilizing Thermal Transfer Sheet) The thermal transfer sheet of the present invention is overlaid on an image receiving sheet in which a polyester resin or the like is coated on a synthetic paper or the like, as in the case of using a thermal transfer sheet having only a sublimable transfer layer. From the back side of the thermal transfer sheet, a thermal head is used to apply heat energy according to image information such as an image or characters or lines to form an image on the resin-coated surface of the image receiving paper and characters and / or lines. be able to. For example, for images and lines, output signals of a color scanner (color separation machine) used in printing plate making are used. A color scanner may be used for the characters, but the output signal of the phototypesetting machine is preferably used. The signals relating to two or more types of information of different types may be individually output to the thermal printer, or may be combined before being output as necessary. Further, by using the layout scanner, it is also possible to use an output signal relating to aggregate information in which information such as images, lines and characters is aggregated. As the thermal head of the printer, only the thermal head for the sublimation transfer sheet is used, however, when transferring the heat-meltable transfer layer, the applied energy may be kept constant for printing, or the sublimation transfer sheet may be printed. A thermal head and a thermal head for thermal melting transfer may be prepared, and heat may be applied to the sublimable transfer layer and the thermal melting transfer layer from separate heads.
When using separate thermal heads, use a finer head than the thermal head for the sublimation transfer sheet as the head for the heat-melt transfer sheet, and use only the thermal head for the sublimation transfer. You can also improve the quality of letters and lines.

[0015]

Since the thermal transfer sheet of the present invention has different types of transfer layers such as a sublimable transfer layer and a heat-meltable transfer layer, the transfer amount of the dye changes depending on the amount of heat applied. Since a sublimable transfer layer is used, a gradational image can be formed, and the heat-meltable transfer layer can transfer the colored binder only after obtaining a certain amount of heat. Can be formed. In some cases, it is also possible to form a solid portion of a special color having a constant hue and hiding, so that each of the printed matter (hard copy) having an image and characters and / or lines exhibits good quality. Can be obtained in the further,
When the dye / binder in the sublimable transfer layer is in the mixed range of 0.3 to 2.3, the print density of the dye image is high,
It is possible to obtain a transfer sheet having high heat sensitivity in printing and good storage stability. Therefore, when you want to form a photo or picture and text on the same sheet of paper as when creating a postcard, the gradation of the photo or picture can be reproduced sufficiently and the text can be clearly formed. When the sublimation transfer method is used as an alternative to, a print extremely close to the actual print can be obtained. There are advantages.

[Brief description of drawings]

FIG. 1 is a sectional view of a thermal transfer sheet of the present invention.

FIG. 2 is a sectional view of the thermal transfer sheet of the present invention.

FIG. 3 is a 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]

 DESCRIPTION OF SYMBOLS 1 Thermal transfer sheet 2 Sheet-shaped base material 3 Sublimable transfer layer 4 Thermal melting transfer layer

Claims (1)

[Claims] 1. A first thermal transfer layer containing a dye which is melted or sublimated by heating to be transferred in a non-heat transfer resin binder, and the dye / binder is in a mixed range of 0.3 to 2.3. A heat transfer sheet, comprising: a second heat transfer layer, which is colored with a binder that is melted and transferred by heating, on the same surface of a sheet-shaped substrate.