JPH11348435A - Thermal transfer sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain good quality in each recorded matter having images, characters and/or lines together by having a sublimation transfer layer and a transfer layer of a diverse type such as in a heat-melt transfer layer. SOLUTION: The thermal transfer sheet 1 has in turn on one surface of a sheet base material 2 repeatedly a three-color sublimation transfer layer 3 of yellow Y, magenta M, and cyan C and a heat-melt transfer layer 4 of black Bk, and by employing this heat transfer sheet 1, an image plane is obtained having partly the mixed three-color gradation of yellow, magenta, and cyan in the sublimation transfer layer 3, or by the heat-melt transfer layer 4, high density, uniform, and black characters and lines can be obtained. Herein, the sublimation transfer layer 3 is of the type that dye transferred by being melted or sublimated through heating is contained in a nonheat transfer binder, and the heat-melt transfer layer 4 consists of a heat-melt binder and coloring agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portion requiring gradation, such as a photograph or a painting, and a region which is not required to have gradation, such as a character, a line, or an area to be painted in a single color, but has a clear and high density. The present invention relates to a thermal transfer sheet that can be formed by transferring a portion required to be formed by a thermal transfer method using the same thermal transfer sheet.

[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 superimposed on paper or the like coated with a polyester resin, and heated from a thermal transfer sheet side by a thermal head to form dots. (Hereinafter, referred to as a sublimation transfer method) has been attempted. According to such a sublimation transfer method, the amount of dye to be transferred can be controlled according to the density of an image, so that there is a gradation. An image can be formed. 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, since a portion of the heat-transfer layer which has been heated to the melting point or more is transferred together with the binder, the amount of the substance to be transferred is larger than when only the dye is transferred in the sublimation transfer method. Although there is an advantage that clear transfer can be performed at a high uniform density, it is not suitable for forming an image with gradation because it is basically a binary one of transferring or not transferring. 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 are simultaneously present in one page on the same paper, such as when sublimation transfer or hot melt transfer is used. Did not produce enough prints and did not obtain the desired quality.

[0005]

One of the problems to be solved in the present invention is that a portion requiring gradation, such as a photograph or a picture, and clarity and high density such as characters and lines are required. It is to eliminate the point that it has been difficult to form a part simultaneously by either the sublimation transfer method or the hot-melt transfer method, and the second problem to be solved in the present invention is to multiply by 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 an attempt is made to apply a possible color to a relatively large area.

[0006]

According to the present invention, a heat transfer sheet is constituted by a first heat transfer layer containing a dye which transfers by melting or sublimation by heating in a non-heat transferable resin binder. A heat transfer sheet having a second heat transfer layer, which is colored with a binder that is melted and transferred by heating, on the same plane as the sheet-like base material, wherein the end of the sheet base material or between each transfer layer The above problem can be solved by providing a detection mark on each of the transfer layers and arranging the transfer layers in order from the one having a large thermal energy required for transfer, and sequentially transferring the colors when the respective colors are overlapped. .

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 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, as the heat-fusible transfer layer, although only one color of black (Bk) is normally sufficient for expressing characters and lines,
k) may be provided in place of a special color, or both black and a special color may be provided. The number of spot colors can be increased if desired. Alternatively, yellow (Y) as a heat-fusible transfer layer,
Three colors of red (M) and blue (C) or even black (B
k) may be added to a four-color heat-fusible transfer layer, or a special color may be added to these three or 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 not limited to the examples shown in FIGS. 1 to 3, and the two types of thermal transfer layers, the sublimable transfer layer and the heat-fusible transfer layer, can be formed on the same thermal transfer sheet. The provision of the heat transfer layer enables transfer utilizing the characteristics of the thermal transfer layer of each type, and the color of the thermal transfer layer of each type can be arbitrarily determined.

The material for forming each part of the thermal transfer sheet and the method for producing the thermal transfer sheet according to the present invention are described below.

(Sheet-like substrate) The sheet-like substrate 2 of the present invention may be made of plastic, polyester, polypropylene, cellophane, polycarbonate, cellulose acetate, polyethylene, polyvinyl chloride, or the like.
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-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.
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,
54, 79, 60, 23, 7, 141, C.I. I. Disperse Blue 24, 56, 14, 301, 334, 165, 19, 72, 8
7, 287, 154, 26, C.I. I. Disperse thread 135, 146, 5
9, 1, 73, 60, 167, C.I. I. Disperse Violet 4, 13 and 3
6, 56 and 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, 3
6, 50, 49, 111, 105, 97, 11, C.I. I. Solvent Red 135, 81, 18, 25, 19, 23, 24, 143, 146,
182.

As the binder for 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, cellulose resins such as ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxy cellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate, and cellulose acetate butyrate, polyvinyl alcohol, polyvinyl butyral, polyvinyl pyrrolidone, polyester, polyvinyl acetate, and vinyl acetate such as polyacrylamide Resin can be used.

As a more preferred example of the binder, instead of the above-mentioned ordinary polyvinyl butyral resin, the molecular weight is 60,000 to 200,000, and the weight percentage of the vinyl alcohol portion is 10 to 40 in the polyvinyl butyral resin.
%, Preferably 15 to 30%, and a glass transition point of 60 ° C.
A special polyvinyl butyral resin having a temperature of 110 ° C, preferably 70 ° C to 110 ° C, may be used. Molecular weight 60,00
If it is less than 0, the binding power as a binder is insufficient,
If it exceeds 200,000, the viscosity at the time of application becomes too high, which hinders application. 10% vinyl alcohol
If it is less than 1, the thermal transfer layer has insufficient stability over time, so that aggregation and precipitation of the dye and bleeding on the surface 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 is preferably such that the ratio of the dye to the binder is at least 0.3, 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 is 0.3-2.
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 binder are kneaded with a solvent so as to have a predetermined ratio, preferably dissolved in a 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 by coating.

(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 the like, 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, waxes Various waxes such as beeswax, whale wax, wart wax, wool wax, shellac wax, candelilla wax, petrolatum and the like can be used.

As the binder resin, for example, EV
A, 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, polyacetal, or the like can be used.

As the colorant, an organic or inorganic pigment or dye having good properties as a recording material, for example, having a sufficient coloring density,
Those which do not discolor by heat and temperature are preferred. 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 formed into a hot-melt ink by a method such as melting and mixing the binder and the colorant described above. Specifically, it can be applied by a method such as hot lacquer coating, gravure coating, gravure reverse coating, roll coating, gravure printing, bar coating, and the like.
~ 30μ, preferably 1-20μ.

(Other Configurations) In order to prevent sticking due to the heat of the thermal head when printing from the back side and to improve slippage, the thermal transfer sheet is treated on the side of the sheet-like substrate on which the thermal transfer layer is not provided. It is better to apply.

For example, a heat-resistant slip layer mainly composed of (1) a reaction product of a polyvinyl butyral resin and an isocyanate, (2) an alkali metal salt or an alkaline earth metal salt of a phosphate, and (3) a filler. Should be provided. The polyvinyl butyral resin has a molecular weight of about 60,000 to 200,000 and a glass transition point of 60 to 110 ° C. Further, from the viewpoint of a large number of reaction sites with isocyanate, the weight% of the vinyl alcohol moiety is 15 to 100%. 40% is better.

As the alkali metal salt or alkaline earth metal salt of phosphate ester, Gaffa RD7 manufactured by Toho Chemical Co., Ltd.
20 or the like is used, and it is preferable to use about 1 to 50% by weight, preferably about 10 to 40% by weight based on the polyvinyl butyral resin.

The heat-resistant slip layer desirably has a heat-resistant layer as a lower layer, and is a combination of a synthetic resin curable by heating and a curing agent thereof, for example, polyvinyl butyral and polyvalent isocyanate, acrylic polyol and polyvalent isocyanate, cellulose acetate. And a combination of titanium and a chelating agent or polyester and an organic titanium compound.

In the thermal transfer sheet, the thermal printer can detect the boundary between the sublimation 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 superposed 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 individually output to a thermal printer, or may be output after combining both as necessary.

Further, by using a layout scanner, it is possible to use an output signal relating to aggregate information in which information such as images, lines, and characters are aggregated.

As a thermal head of a 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 A thermal head for transfer 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, as a head for the hot-melt transfer sheet,
The quality of characters and lines can be improved as compared with the case where only a thermal head for sublimation transfer is used by using a higher definition than the thermal head for sublimation transfer sheet.

[0035]

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 amount of the dye changes according to the amount of heat applied. Uses a sublimable transfer layer to obtain a gradation image, and a high-density clear letter and line due to a heat-fusible transfer layer that can transfer a colored binder only after obtaining a certain amount of heat. Can be formed. Further, in some cases, a solid portion having a constant hue and a opaque special color can be formed, so that an image and a recorded matter (hard copy) having both characters and / or lines exhibit good quality. It can be obtained in a state where it is done. further,
When the dye / binder of the sublimation 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 thermal sensitivity in printing and excellent storage stability. Furthermore, by using black in addition to yellow, magenta, and cyan for the sublimation transfer layer, the shadow portion is appropriately emphasized, the tone reproducibility is further improved, and a higher quality color tone image is obtained. Can be

Accordingly, when it is desired to form a photograph, a picture and a character on the same sheet, such as when creating a postcard, the gradation of the photograph or the picture can be sufficiently reproduced and the character can be formed clearly.
Further, when a sublimation transfer method is used as a substitute for proof printing, 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]

DESCRIPTION OF SYMBOLS 1 ... Thermal transfer sheet, 2 ... Sheet-like base material, 3 ... Sublimation transfer layer, 4 ... Hot-melt transfer layer

Claims (1)

[Claims] 1. A first heat transfer layer containing a dye that transfers by melting or sublimation by heating in a non-heat transferable resin binder, and a first heat transfer layer in which the binder that transfers by melting and transferring by heating is colored. A thermal transfer sheet having two thermal transfer layers on the same plane of a sheet-like base material, wherein a detection mark is provided at an end of the sheet base material or between each transfer layer, and each transfer layer is necessary for transfer. A thermal transfer sheet which is arranged in order from the one having the largest thermal energy and is successively transferred when each color is overlapped.