JPH06286346A - Heat transfer sheet - Google Patents

Abstract

PURPOSE:To improve such properties as reproducibility in cyan color, coloring density, clearness and various fastnesses by using a mixture, wherein the dye expressed by another formula is mixed into a mixture of the dyes expressed by three kinds of specified formulas, for the dye contained in a dye layer. CONSTITUTION:A heat transfer sheet is constituted by forming a dye layer on one surface of a base material sheet. The dye contained in the dye layer is made to be the mixture, wherein the dye expressed by another formula is further mixed into the mixture of the dyes expressed by the three kinds of formulas shown in the figure. The mixing ratio of the dyes is set in the following relationship. Namely, when the dye of the second formula containing NHCH3 is made to be a part (x), 0<=x<=30 is set; the dye of the third formula containing NH2 is set as dye=(1-0.2x) to (15-0.5x) (0<=x<=5) and 0 to (15-0.5x) (5<=x<=30); and the dye of the first formula containing NHCOCH3 is set as dye = first formula + second formula + third formula = 100. The mixing ratio between the dyes from the first formula to the third formula and the dye of the fourth formula is set at 55:45-95:5.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a thermal transfer sheet,
More specifically, it is an object of the present invention to provide a thermal transfer sheet which can easily give a recorded image excellent in cyan color reproducibility of a document and excellent in color density, sharpness and various fastnesses to an image receiving sheet.

[0002]

2. Description of the Related Art Conventionally, various sublimation-type thermal transfer methods have been known, and in recent years, due to advances in recording methods, a thermal head or the like has been used to provide a dye receiving layer on a polyester sheet or paper at high speed. It is possible to form delicate characters and figures or full-color photographic images on these image receiving sheets by using such image receiving sheets.

[0003]

In the above-mentioned prior art, when a full-color image of an original is reproduced by using the three primary colors of yellow, cyan and magenta, the transferred dye has an excellent coloring density and clear color. Properties and fastness are required, and for example, in the case of a cyan dye, it is required to develop a cyan color having a color tone that sufficiently matches the color development of other yellow and magenta colors.

Various dyes have been proposed to meet these demands. However, in the case of a dye excellent in color density, vividness and various fastnesses, in many cases, the matching property with other colors is unsatisfactory. In many cases, the full-color image of the original cannot be accurately reproduced after all. Of this matching
The requirement does not have to be that the color developability or sharpness of the dye is good, but is an essential requirement at the time of forming a full-color image even if the color developability of the dye is sacrificed to some extent.
Another problem is that when a thermal transfer sheet is stored for a long period of time, the sublimability of the dye is lowered due to the precipitation of the dye and the transferability of the dye in the highlight portion is lowered during image formation. Therefore, an object of the present invention is to provide a thermal transfer sheet capable of easily giving a recorded image having excellent reproducibility of cyan color of an original and excellent color density, sharpness, various fastnesses and storability to an image receiving sheet. It is to be.

[0005]

The above object can be achieved by the present invention described below. That is, the present invention comprises a substrate sheet and a dye layer formed on one surface of the substrate sheet,
The dye contained in the dye layer is represented by the following formula (4) in a mixture of the dye represented by the formula (1) and the dye represented by the formula (2) and / or (3). A thermal transfer sheet characterized by being a mixture of dyes.

[Chemical 5]

[Chemical 6]

[Chemical 7]

[Chemical 8]

[0006]

The dye of the above formula (1) shows a clear cyan color tone and an excellent heat transfer property as a dye for a heat transfer sheet and forms a high density and clear image. In addition, it does not match well with magenta color and is clearer than the original, and forms a slightly bluish full-color image, but is mixed with the dye represented by the formula (2) and / or (3). As a result, although the sharpness and the like are lowered to some extent, the matching property with other colors is good, and the full-color image of the original can be accurately reproduced by using it together with the yellow color and the magenta color. Further, by mixing and using the dye of formula (4), when it is stored as a thermal transfer sheet for a long period of time, the sublimability of the dye is lowered due to the precipitation of the dye and the transferability of the dye in the highlight portion during image formation is lowered. The problem of doing is solved.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described in more detail with reference to preferred embodiments. A preferred mixing ratio of the dye of formula (1) and the dye of formula (2) and / or (3) is
When the dye of formula (2) is defined as x part, 0 ≦ x ≦ 30 dye of formula (3) = (1-0.2x) to (15-0.5)
x) (0 ≦ x ≦ 5) 0- (15−0.5x) (5 ≦ x ≦ 30) Dye of Formula (1) = Formula (1) + Formula (2) + Formula (3) = 10
0 This range is shown in FIG. If either one is too little or too much, matching with other colors becomes insufficient, which is not preferable. Further, the preferable mixing ratio of the dye represented by the formula (4) to the above dye mixture is
The weight ratio is 55:45 to 95: 5. If the amount of the dye of the formula (4) is too small, there is no effect of improving the storage stability of the thermal transfer sheet. On the other hand, if the amount of the dye of the formula (4) is too large, the coloring hue deviates from the standard color, which is not preferable. The thermal transfer sheet of the present invention is characterized by using the specific dye mixture as described above, and other configurations may be the same as those of conventionally known thermal transfer sheets.

The substrate sheet used for the thermal transfer sheet of the present invention may be any one as long as it has a conventionally known degree of heat resistance and strength, for example, 0.5.
Paper having a thickness of about 50 μm, preferably about 3 to 10 μm,
Various processed papers, polyester films, polystyrene films, polypropylene films, polysulfone films, polycarbonate films, aramid films, polyvinyl alcohol films, cellophane, etc., and particularly preferred are polyester films.

The dye layer provided on the surface of the substrate sheet as described above is a layer in which the dye mixture is supported by an arbitrary binder resin. As the binder resin for supporting the dye mixture, any conventionally known one can be used, and preferable examples include ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxycellulose, hydroxypropyl cellulose, ethyl hydroxyethyl cellulose, methyl cellulose, Cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate,
Cellulose derivatives such as cellulose nitrate, polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl acetoacetal, polyvinyl pyrrolidone, polystyrene, vinyl resins such as polyvinyl chloride, polyacrylonitrile, acrylic resins such as polyacrylic acid ester, polyamide resin, Examples thereof include polyester resins, polycarbonate resins, phenoxy resins, phenol resins, epoxy resins, and air elastomers, which may be mixed or copolymerized for use, or may be crosslinked with various crosslinking agents. In particular, polyvinyl butyral and polyvinyl acetal are preferable from the viewpoint of heat resistance and dye migration. The dye layer of the thermal transfer sheet of the present invention,
Although it is basically formed of the above-mentioned materials, other organic fillers such as polyethylene powder and various additives similar to conventionally known ones may be included, if necessary.

Such a dye layer is preferably prepared by adding the above-mentioned dye mixture, binder resin and other optional components to a suitable solvent to dissolve or disperse each component to prepare a coating liquid or ink for forming a dye layer. This is applied and dried on the above-mentioned base material sheet to be formed. The dye layer thus formed has a thickness of 0.2 to 5.0 μm, preferably 0.4 to 2.0.
The dye mixture in the dye layer has a thickness of the order of 5 μm, and the above dye mixture in the dye layer is 5 to 70% by weight, preferably 10% by weight.
It is preferably present in an amount of -60% by weight.

The thermal transfer sheet of the present invention as described above is sufficiently useful as it is for thermal transfer. However, an anti-adhesion layer, that is, a release layer may be further provided on the surface of the dye layer. By providing the layer, it is possible to prevent the thermal transfer sheet and the image receiving sheet from sticking to each other during thermal transfer, use a higher thermal transfer temperature, and form an image with a more excellent density.

As this release layer, even if only an anti-adhesive inorganic powder is attached, a considerable effect is exhibited, and further,
For example, from a resin having excellent releasability such as a silicone polymer, an acrylic polymer, or a fluorinated polymer, 0.01 to
It can be formed by providing a release layer having a thickness of 5 μm, preferably 0.05 to 2 μm. In addition, even if the above-mentioned inorganic powder or releasing polymer is included in the dye layer, a sufficient effect can be obtained. Further, a heat-resistant layer may be provided on the back surface of such a thermal transfer sheet in order to prevent adverse effects due to the heat of the thermal head.

The image-receiving sheet used for forming an image by using the above-mentioned thermal transfer sheet may be any one as long as its recording surface has dye receptivity to the above-mentioned dye, and Paper, metal, which does not have dye receptivity
In the case of glass or synthetic resin, a dye receiving layer may be formed on at least one surface thereof.

Examples of the image-receiving sheet which does not need to form a dye-receiving layer include polyolefin resins such as polypropylene, halogenated polymers such as polyvinyl chloride and polyvinylidene chloride, vinyl such as polyvinyl acetate and polyacrylic ester. Polymers, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polystyrene resins, polyamide resins, copolymer resins of olefins such as ethylene and propylene with other vinyl monomers, cellulosic resins such as ionomers and cellulose diacetate. Examples include fibers, woven fabrics, films, sheets, and molded products made of polycarbonate, etc.

Particularly preferred is a sheet or film made of polyester or processed paper provided with a polyester layer. Even for non-dyeing image-receiving sheets such as paper, metal, glass, etc., a solution or dispersion of the above-mentioned dyeing resin is applied to the recording surface and dried, or a resin film thereof is used. An image-receiving sheet can be obtained by laminating the.

Further, even in the above-mentioned dye-receptive image-receiving sheet, a dye-receptive layer may be formed on the surface of the image-receptive sheet, as in the case of the above paper, from a resin having a better dyeing property. The dye-receptive layer thus formed is
Further, it may be formed from a plurality of materials, and it is a matter of course that various additives may be included within the range not impairing the intended purpose.

Such a dye receiving layer may have any thickness, but is generally 3 to 50 .mu.m thick. Further, such a dye receiving layer is preferably a continuous coating, but it may be formed as a discontinuous coating by using a resin emulsion or a resin dispersion. Such an image-receiving sheet is basically as described above and can be used satisfactorily as it is. However, the image-receiving sheet or its dye-receiving layer should contain inorganic powder for preventing tackiness. By doing so, even if the temperature at the time of thermal transfer is raised, the adhesion between the thermal transfer sheet and the image receiving sheet can be prevented, and more excellent thermal transfer can be performed. Particularly preferred is finely divided silica.

Further, in place of or in combination with the above-mentioned inorganic powder such as silica, a resin having good releasability as described above may be added. Particularly preferable releasing polymer is a cured product of a silicone compound, for example, a cured product of an epoxy-modified silicone oil and an amino-modified silicone oil. Such a release agent is preferably contained in an amount of about 0.5 to 30% by weight based on the weight of the dye receiving layer.

Further, the image-receiving sheet to be used may have the above-mentioned inorganic powder adhered to the surface of the dye-receiving layer to enhance the tack-preventing effect, and it has excellent releasability as mentioned above. You may provide the layer which consists of a mold release agent. Such a release layer exerts a sufficient effect with a thickness of about 0.01 to 5 μm, and can prevent the adhesion of the thermal transfer sheet to the dye receiving layer and further improve the dye receiving property.

As the means for applying the thermal energy used when performing thermal transfer using the thermal transfer sheet of the present invention as described above and the recording material as described above, any conventionally known applying means can be used. By controlling the recording time with a recording device such as a printer (for example, Hitachi, video printer VY-100), 5 to 5
By applying thermal energy of about 100 mJ / mm ² , the intended purpose can be sufficiently achieved.

[0021]

EXAMPLES Next, the present invention will be described more specifically with reference to Examples and Comparative Examples. In the text, parts and% are based on weight unless otherwise specified. Example A dye layer-forming ink composition having the following composition was prepared, and applied to a 6 μm-thick polyethylene terephthalate film having a heat-treated back surface so that the dry coating amount was 1.0 g / m ² and dried. The thermal transfer sheets of the present invention shown in Table 1 below were obtained. Dye mixture of the dyes (1) to (4) (the mixing ratio is as shown in Table 1 below) 3.0 parts in total Polyvinyl butyral resin 4.5 parts Methyl ethyl ketone 46.25 parts Toluene 46.25 parts However, the above When the dye mixture was insoluble in the above composition in the composition, DMF, dioxane, chloroform or the like was appropriately used as the solvent.

Next, a synthetic paper (Yupo FPG # 150, manufactured by Oji Yuka) was used as a base sheet, and a coating solution having the following composition was applied to one surface of the synthetic paper at a rate of 10.0 g / m ² when dried. And then dried at 100 ° C. for 30 minutes to obtain an image receiving sheet. Polyester resin (Vylon200, Toyobo) 11.5 parts Vinyl chloride / vinyl acetate copolymer (VYHH, UCC) 5.0 parts Amino-modified silicone (KF-393, Shin-Etsu Chemical Co., Ltd.) 1.2 parts Epoxy-modified Silly Corn (X-22-343, manufactured by Shin-Etsu Chemical Co., Ltd.) 1.2 parts Methyl ethyl ketone / toluene / cyclohexanone (weight ratio 4: 4: 2) 102.0 parts

The above-mentioned thermal transfer sheet of the present invention and the above-mentioned image receiving sheet are superposed with their dye layers and dye receiving surfaces facing each other, and the head applied voltage 10 is applied from the back surface of the thermal transfer sheet.
V, printing time 4.0 msec. Recording was performed with a thermal head under the conditions of, and the results shown in Table 1 below were obtained.

[0024]

[Table 1]

Storability evaluation method: The thermal transfer sheet of the present invention was superposed on a substrate sheet, and the pressure was applied at 40 g weight / cm ² at 60 ° C.
Store for 24 hours. Each thermal transfer sheet before and after storage is subjected to thermal printer printing on the image receiving paper, and the difference in print density is compared with the comparative example. ⊚: Excellent, ◯: Good, Δ Inferior highlight area transfer evaluation method : The printing density at the time of printing with low thermal energy by a thermal printer is compared with the comparative example. ◎: excellent, ○: good, △ inferior

[0026]

[Effects] According to the present invention as described above, by using a specific dye mixture as the dye of the thermal transfer sheet, the matching property with other colors is good, and the full-color image of the original can be accurately reproduced. Further, when it is stored as a thermal transfer sheet for a long period of time, the problems that the sublimability of the dye is lowered due to the precipitation of the dye and the transferability of the dye in the highlight portion during image formation is also solved.

[0027]

[Brief description of drawings]

FIG. 1 CIE 19 of images of Example 1, Comparative Examples 1 and 2.
76 (L ^* a ^* b ^* ) Figure showing a uniform perceptual color space (a ^* , b ^* ) (measurement was performed with MINOLTA CR-221)

2 is a CIE19 of images of Example 1 and Comparative Examples 1 and 2; FIG.
76 (L ^* a ^* b ^* ) Figure showing uniform perceptual color space (L ^* , a ^* ) (Measurement was performed with MINOLTA CR-221)

FIG. 3 is a CIE19 of images of Example 1 and Comparative Examples 1 and 2;
76 (L ^* a ^* b ^* ) uniform perceptual color space (L ^* , b ^* ) (measurement was performed with MINOLTA CR-221)

FIG. 4 is a diagram showing a preferable mixing ratio of dyes in the present invention.

Claims (3)

[Claims] 1. A substrate sheet and a dye layer formed on one surface of the substrate sheet, wherein the dye contained in the dye layer is a dye represented by the following formula (1) or a compound represented by the following formula: A thermal transfer sheet comprising a mixture of the dye represented by (2) and / or (3) and a dye represented by the following formula (4). [Chemical 1] [Chemical 2] [Chemical 3] [Chemical 4] 2. The thermal transfer sheet according to claim 1, wherein the mixing ratio of the dye represented by formula (1) and the dye represented by formula (2) and / or (3) is a weight ratio having the following relationship. When the dye of formula (2) is defined as x part, 0 ≦ x ≦ 30 dye of formula (3) = (1-0.2x) to (15-0.5)
x) (0 ≦ x ≦ 5) 0- (15−0.5x) (5 ≦ x ≦ 30) Dye of Formula (1) = Formula (1) + Formula (2) + Formula (3) = 10
0 3. A mixture ratio of the mixture of the dye of the formula (1) and the dye of the formula (2) and / or (3) and the dye of the formula (4) is 55:45 to 95. The thermal transfer sheet according to claim 1, having a weight ratio of 5: 5.