JPH07237361A - Composite thermal transfer sheet - Google Patents

Abstract

PURPOSE:To provide a composite thermal transfer sheet excellent in the releasability of a receiving layer and a dye layer at the time of dye printing and imparting sufficiently high printing density. CONSTITUTION:In a composite thermal transfer sheet wherein a receiving layer and at least one color dye layer are successively provided on one surface of a base material sheet, the ratio of the wt. D of the dye layer and the dye binder B in the dye layer is set to 0.5<D/B-<2.5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite thermal transfer sheet, and more particularly to a composite thermal transfer sheet which has excellent releasability between a receiving layer and a dye layer during dye transfer and can provide a high-density printed image.

[0002]

2. Description of the Related Art Conventionally, various thermal transfer methods are known,
Sublimation-type thermal transfer recording in which a transfer sheet having a dye layer containing a sublimable dye and a binder provided on a substrate film is used, and recording is performed according to image information by using a heating means such as a thermal head. The scheme is known. In the above method, even when directly transferred to a paper such as natural paper, a high-concentration image cannot be obtained because the sublimable dye is not dyed, and a plastic sheet excellent in dye receiving property or a dye receiving layer It was necessary to form an image using an image receiving sheet which was previously provided on the base material. In this recording method, it is of course possible to form an image by forming a receiving layer on the surface of ordinary plain paper, but the cost is generally high. For example, postcards, memos, stationery, report papers, etc. It is difficult to use the one in which a receiving layer is previously formed. As a method for solving such a problem, for example, JP-A-62-2
Japanese Patent No. 64994 discloses that when an image is to be formed on a ready-made recording sheet such as plain paper, prior to image formation,
A receiving layer transfer sheet capable of forming a dye receiving layer on a required portion is disclosed. Further, as a further simplified method, in JP-A-62-297184, etc., yellow, magenta, cyan,
And, using a composite thermal transfer sheet provided with a black dye layer if necessary, and further provided with a transferable receiving layer adjacent to the dye layer, first, the dye receiving layer is transferred to a transfer target, and then, A recording method is described in which an image is formed by superimposing each color dye layer on the transfer receiving layer.

[0003]

An image-receiving sheet provided with a dye-receiving layer as described above is superposed on a thermal transfer sheet and heat-recorded from the side opposite to the dye layer using a heating means such as a thermal head. However, at that time, there is a problem that the dye layer and the receiving layer are fused by heat. Therefore, by incorporating a release agent such as silicone oil into the image-receiving layer forming ink and allowing the release agent to bleed out by drying after coating, it is devised so that the release layer is given releasability. Has been done.

However, in a composite thermal transfer sheet in which a receiving layer and a dye layer are provided on the same base material sheet in a frame-sequential manner,
Since the receiving layer is provided on the transfer target by the transfer, the surface of the peeling interface with the substrate, that is, the side opposite to the surface where the release agent bleeds, is the dye-printed screen, which makes it difficult to exhibit releasability. . Therefore, the release agent bleeds out to reduce the releasing component on the transfer sheet substrate side, and prevents the releasability of the receiving layer surface from being insufficient when transferred onto the transfer target. Therefore, in the transfer sheet of the type in which the receiving layer is provided by the transfer as described above, a dispersion-type releasing agent that does not easily bleed out is selected and used. However, just by selecting the release agent in this way, the releasability of the surface of the receiving layer is insufficient, and good releasability cannot be obtained.

On the other hand, in the dye layer, the sublimable dye is retained in the binder. However, if the weight ratio (D / B ratio) of the dye and the binder is increased in order to obtain a high image density, the heat resistance of the dye layer becomes high. However, there is a problem in that the dyeability is deteriorated and the dye is melted by the heat energy during recording, and the dye layer is fused to the receiving layer.

[0006]

In order to solve the above problems, an examination was made to find that the D / B ratio in the dye layer was set within a specific range while maintaining a high printing density and the dye layer to the receiving layer. It was found to be effective in preventing abnormal transfer due to fusion between layers. That is, the composite thermal transfer sheet of the present invention is a composite thermal transfer sheet in which a releasable receiving layer region and a dye layer of at least one color are provided face-sequentially on one surface of a base sheet, The ratio of the dye weight D and the dye binder weight B in each of the dye layers is 0.5 <D / B <2.5. Further, in the composite thermal transfer sheet, D / B in the final color of the dye layer is 0.5 <D / B <2.0.

[0007]

By the proper ratio of the binder having excellent heat resistance and the dye having poor heat resistance in the dye layer, it is possible to obtain a composite thermal transfer sheet with a high image density and less abnormal transfer. In particular, by setting the D / B ratio in the final color within a specific range, it is possible to more efficiently achieve both image density and heat resistance. Further, by reducing the D / B ratio of the final color, it is possible to compensate for the insufficient releasability as the printing process progresses.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to the preferred embodiments. The substrate sheet used in the composite 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, and is, for example, 0.5 to 50 μm, preferably 3 to 10 μm.
m-thick paper, various processed papers, polyethylene terephthalate film and other polyester films,
Polystyrene film, polypropylene film, polysulfone film, polyphenylene sulfide film, polyethylene naphthalate film, 1,4-polycyclohexylenedimethyl terephthalate film, aramid film, polycarbonate film, polyvinyl alcohol film, cellophane, etc., and particularly preferred are polyester films. Is. These substrate sheets may be single-wafer type or continuous film and are not particularly limited. Among these, polyethylene terephthalate film is particularly preferable,
It is also preferable to provide an adhesive layer (primer layer) on one or both surfaces of the film, if necessary.

On the surface of the above-mentioned substrate on which the dye layer is not provided (rear side), in addition to preventing fusion of the thermal head and improving running property, the composite thermal transfer sheet of the present invention is wound into a roll. In order to prevent the back surface and the receiving layer surface from adhering to each other at the same time, it is desirable that the back surface side of the base film is provided with heat resistant slip resistance and releasability. Examples of such a releasable heat resistant slipping layer include curable silicone oil,
It is formed from a release agent such as curable silicone wax, silicone resin, fluorine resin, acrylic resin, or the like. Further, the releasable heat resistant slipping layer uses a thermoplastic resin having an -OH group or a -COOH group, a compound having two or more amino groups, or a compound obtained by reacting diisocyanate or triisocyanate and crosslinking and curing. You can also

As the resin forming the dye receiving layer of the present invention, a receiving layer resin conventionally used in a sublimation transfer recording system can be used. For example, a polyolefin resin such as polypropylene, polyvinyl chloride, vinyl chloride / vinyl acetate. Copolymers, halogenated polymers such as polyvinylidene chloride, vinyl polymers such as polyvinyl acetate and polyacrylic ester, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polystyrene resins, polyamide resins, ethylene, propylene, etc. The copolymer resin of olefin and other vinyl monomer, ionomer, cellulose resin such as cellulose diacetate, polycarbonate and the like can be used alone or in a mixture. In particular, vinyl resins and polyester resins are preferable in terms of color developability, releasability and image storability.

Further, in the above-mentioned receiving layer, a known release agent may be mixed in order to more effectively prevent fusion with the dye layer. Preferred releasing agents used include silicone oils, phosphate ester type surfactants, fluorine type surfactants and the like, but silicone oils are preferable from the viewpoint of releasing effect. As the silicone oil, epoxy modified, alkyl modified, amino modified, carboxyl modified,
Modified silicone oils such as alcohol-modified, fluorine-modified, alkylaralkylpolyether-modified, epoxy-polyether-modified and the like are desirable. These release agents may be used alone or in combination, and the dye receiving layer forming resin 100 may be used.
A ratio of 0.5 to 30 parts by weight is suitable with respect to parts by weight.

Further, the receptive layer as described above is charged with an electrostatic charge in order to prevent tail fins due to defective film breakage, which occur when the receptive layer is transferred to the transferred material, from being reversed by static electricity and attached to the sublimation dye layer. You may mix | blend an inhibitor. As the antistatic agent used, known nonionic surfactants, anionic surfactants, amphoteric surfactants and the like can be used,
It is preferable to add the solid content (weight ratio) of the receiving layer in a proportion of 0.001 to 5%.

The receiving layer is provided on one surface of the base film,
A resin obtained by adding an arbitrary additive to the resin as described above is dissolved in an appropriate organic solvent, or a dispersion prepared by dispersing it in an organic solvent or water is used, for example, a gravure printing method, a screen printing method, or a gravure plate. It is formed by applying and drying by a forming means such as the reverse roll coating method. The dye receiving layer formed as described above may have any thickness, but is generally 0.5 to 15 μm. 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 liquid.

In the present invention, a peeling layer may be provided between the base material and the receiving layer in order to improve the peeling of the receiving layer from the base material. As the release layer, waxes, silicone waxes, silicone resins, fluororesins, acrylic resins, urethane resins, cellulose resins, polyvinyl butyral resins, polyvinyl acetal resins, etc. can be used. The forming method may be the same as the forming method of the dye receiving layer, and the thickness thereof is about 0.5 to 5 μm. When a matte receiving layer is desired after transfer, the surface is matted by including various particles in the release layer or by using a base film having the surface on which the release layer is formed matted. be able to. This release layer is
If the base film has releasability, it can of course be omitted.

Further, in the present invention, the surface of the above-mentioned receiving layer is
An adhesive layer may be provided in order to improve the transferability of these layers. The adhesive layer is formed by using a heat-sensitive adhesive that does not have adhesiveness at room temperature and exhibits adhesiveness when heated, or an adhesive type adhesive that has adhesiveness at room temperature, for example, a known heat-sensitive adhesive or pressure-sensitive adhesive. Agents or adhesives can be used. Above all, a heat-sensitive adhesive is preferable because it does not have a sticky feeling at room temperature. Even when a composite thermal transfer sheet using this heat-sensitive adhesive is wound in a roll, the release-resistant heat-slip layer provided on the back side and the non-sticky heat-sensitive adhesive synergistically bond the base sheet. Blocking of the agent layer and the back surface can be prevented.

As the above-mentioned heat-sensitive adhesive, it is desirable to use a thermoplastic resin that softens when heated and pressed and exhibits tackiness. Examples of the thermoplastic resin include polyamide resin, acrylic resin, vinyl resin, vinyl chloride / vinyl acetate copolymer resin, synthetic rubber resin, EVA resin,
Examples include ethylene resins. The adhesive layer is preferably formed of a thermoplastic resin having a glass transition temperature of 50 ° C to 80 ° C. The reason for this is that in the case of a resin having a glass transition temperature of less than 50 ° C, blocking and various problems associated with it occur when it is wound into a roll and stored, and the image-receiving sheet has a rough paper like a postcard. In the case of the above, the fluidity of the heat-melted adhesive may be too high, so that the paper may be soaked into the paper and the cushioning effect may be deteriorated. on the other hand,
The glass transition temperature of the thermoplastic resin forming the adhesive layer is 8
When the temperature exceeds 0 ° C., when the dye receiving layer is transferred by the thermal head, when the environmental temperature is low (for example, in cold regions or winter), the fluidity of the melted adhesive is too low and the adhesiveness is poor. This is because it may be sufficient. The adhesive layer preferably has a melt viscosity at 160 ° C. of 1 to 100 poise. If it is lower than 1 poise, the fluidity of the melted adhesive is too high, so that the amount of the adhesive soaked in is large and the cushioning effect cannot be obtained. On the other hand, if it is larger than 100 poise, the fluidity of the melted adhesive is too low to obtain a sufficient adhesive force. Examples of such an adhesive resin include a resin having good adhesiveness at the time of heating, such as a polyamide resin, an acrylic resin, a vinyl chloride resin, a vinyl chloride / vinyl acetate copolymer resin, and a polyester resin, and an appropriate glass transition temperature. Select those that have. Then, the solution is applied and dried to form an adhesive layer.

Further, in the present invention, an intermediate layer may be provided between the receiving layer and the adhesive layer in order to provide cushioning properties and / or hiding properties. The intermediate layer is formed by containing bubbles, a white pigment, or a fluorescent whitening agent. Such an intermediate layer may be divided into a layer containing bubbles and a layer containing a white pigment or the like and formed as separate layers. By providing the base sheet with cushioning properties in this manner, the adhesion between the dye layer and the receiving layer is maintained, and not only the rough portion of the image is prevented from the highlight portion to the halftone of the image,
A high density and clear image can be obtained. The intermediate layer that provides the above-mentioned concealing property is provided in a thickness of 2 to 10 μm by a method such as gravure printing, screen printing, or flexographic printing using a white pigment or a fluorescent whitening agent with a normal ink.

The intermediate layer containing bubbles is a polyurethane resin,
Acrylic resin, butadiene rubber, polyamide resin, epoxy resin, and the like can be used as the main components and can be formed by the following method. An ink mixed with a foaming agent is applied onto a base material sheet, and the dye receiving layer is foamed by heat when transferring. An ink mixed with a foaming agent is coated on a base material sheet, and heated and foamed. The foaming agent in this case is dinitropentane methylenetetramine, which decomposes with heat to generate gases such as carbon dioxide and nitrogen,
Diazoaminobenzene, azobisisobutyronitrile,
Decomposition type foaming agent such as azocarbonamide, or butane,
Any known foaming agent such as microspheres in which a low boiling point liquid such as pentane is made into a microcapsule with a resin such as polyvinylidene chloride or polyacrylonitrile can be used.
This microsphere is preferable in that it does not cause defects such as pinholes in the printed image because the bubbles have outer walls even after foaming.

The dye layer provided in the composite thermal transfer sheet of the present application is a layer in which a dye is carried by an arbitrary binder.
The dye to be used is a dye that melts, diffuses, or sublimes by heat, and the dyes used in conventionally known thermal transfer sheets can be effectively used in the present invention. Properties and solubility in binder are selected. Preferred dyes include, for example, diarylmethane type, triarylmethane type, thiazole type,
Methocyanines such as merocyanine, indoaniline, acetophenone azomethine, pyrazoloazomethine, imidazole azomethine, imidazoazomethine, azomethine typified by pyridone azomethine, xanthene, oxazine, dicyanostyrene, cyanomethylene typified by tricyanostyrene System, thiazine system, azine system, acridine system, benzeneazo system, pyridone azo, thiophene azo, isothiazole azo, pyrrole azo, pyral azo, imidazole azo, thiadiazole azo, triazole azo, azo group such as diazo group, spiropyran system, indolinospiropyran system, Fluoran series, rhodamine lactam series, naphthoquinone series, anthraquinone series, and quinophthalone series. Specifically, the following dyes are used, for example. CI (Color Index) Disperse Yellow 51,3,54,79,6
0,23,7,141 CI Disperse Blue 24,56,14,301,334,165,19,72,8
7,287,154,26,354, CI Disperse Red 135,146,59,1,73,60,167 CI Disperse Orange 149 CI Disperse Violet 4,13,26,36,56,31 CI Disperse Yellow 56,14,16,29,201 CI Solvent Blue 70,35,63,36,50,49,111,105,97,1
1 CI Solvent Red 135,81,18,25,19,23,24,143,146,
182 CI Solvent Violet 13 CI Solvent Red 135,81,18,25,19,23,24,143,146,
182 CI Solvent Violet 13 CI Solvent Black 3 CI Solvent Green 3 For example, as a cyan dye, Kayaset Blue 714 (Nippon Kayaku, Solvent Blue 63) Foron Brilliant Blue-SR (Sand, Disperse Blue 354) ,
Waxolin AP-FW (ICI, Solvent Blue 3
6), as a magenta dye, MS-REDG (Mitsui isobaric, Disperse Red 60), Macrolex Violet R (Bayer, Disperse Violet 26),
Foron Brilliant Yellow S- as a yellow dye
6GL (manufactured by Sand, Disperse Yellow 231), Macrolex Yellow 6G (manufactured by Bayer, Disperse Yellow 201) and dyes represented by the following structural formulas can be used.

[0020]

[Chemical 1]

[0021]

[Chemical 2]

[0022]

[Chemical 3]

[0023]

[Chemical 4]

[0024]

[Chemical 5]

[0025]

[Chemical 6]

[0026]

[Chemical 7]

As the binder resin for supporting the dye as described above, known binder resins can be used. Examples thereof include cellulose resins such as ethyl cellulose, ethyl hydroxycellulose, hydroxypropyl cellulose, methyl cellulose and cellulose acetate, polyvinyl alcohol, Examples include vinyl resins such as polyvinyl acetate, polyvinyl butyral, polyvinyl acetal, and polyvinylpyrrolidone, acrylic resins such as poly (meth) acrylate, poly (meth) acrylamide, polyurethane resins, polyamide resins, polyester resins, etc. Alternatively, they can be optionally used by mixing. Of these, polyvinyl butyral and polyvinyl acetal are preferable from the viewpoint of releasability from the receiving layer during printing.

In the present invention, the ratio of the dye contained in the dye layer is such that the ratio of the dye weight D and the dye binder weight B (D / B ratio) is in the range of 0.5 <D / B <2.5. It is desirable to prepare so that When the amount is smaller than the above range, the amount of the dye contained is reduced, and an appropriate color density cannot be obtained. Further, when it is larger than the above range, the heat resistance of the dye layer is lowered, so that the receiving layer and the dye layer are heat-sealed at the time of heat recording, the halftone reproducibility is deteriorated, or in an extreme case, the image There is a problem that the base material is destroyed in the high-concentration portion. When the dye layer of the present invention contains two or more kinds of dyes and a binder, the total amount of the dyes may be considered as D, and the total amount of the binders may be considered as B. The dye layer is yellow,
The dye layer is formed from one or more dye layers of magenta, cyan and, if necessary, black. When the dye layers of two or more colors are formed in the frame order, the D / B ratio of the dye layer of the final color is 0.
It is desirable that 5 <D / B <2.0. Final color D
By setting the / B ratio within the above range, abnormal transfer can be prevented. Further, by making the D / B ratio of the final color smaller than that of the other dye layers, it is possible to prevent heat fusion more effectively. For example, when the dye layers are formed in the order of yellow, magenta, and cyan, it is desirable that the cyan dye layer has a smaller D / B ratio than the other colors. In this case, if the thermal sensitivities of the yellow, magenta, and cyan dyes are the same, the density of the cyan dye will be low, so the density balance will be good, and the D / B ratio will be low. For the dye layer, it is preferable to use a dye having excellent thermal sensitivity. As described above, it is particularly necessary to set the D / B ratio of the dye layer of the final color within a certain range because the releasable components such as silicone on the surface of the receiving layer decrease as the printing process progresses. This is because abnormal transfer most often occurs when printing a color dye layer. That is, each time one-color printing is performed, the releasable component on the surface of the receiving layer is taken by the dye layer side,
At the time of final color printing, it is important to keep the D / B ratio of the final color within a certain range, since the surface has the least releasing component and the releasing property between the receiving layer and the dye layer is insufficient. Because there is.

In addition to the dye and binder resin as described above,
Further, various additives are added as required, and the dispersion prepared by dissolving in an appropriate organic solvent or dispersing in an organic solvent or water is formed by a gravure printing method, a screen printing method, a reverse roll coating method using a gravure plate, etc. A dye layer can be formed by applying the composition onto the base sheet and drying it by a means. The thickness of the dye layer formed as described above is 0.2.
A thickness of ˜5.0 μm, preferably 0.4 to 2.0 μm is suitable. An anti-adhesion layer, that is, a releasing layer may be provided on the surface of the dye layer in order to prevent abnormal transfer. The release layer is made of a resin having an excellent release property such as an anti-adhesive inorganic powder, a silicone polymer, an acrylic polymer, or a fluorinated polymer and has a thickness of 0.01 to 5
A layer of μm, preferably 0.05 to 2 μm can be provided. Further, a releasable binder obtained by grafting a releasable segment such as a silicone segment, a fluorocarbon segment, or a long chain alkyl segment on the binder resin forming the dye layer may be used.

[0030]

【Example】

Examples 1 to 6 A polyethylene terephthalate long film having a thickness of 6 μm (Lumirror: manufactured by Toray Industries, Inc., width 10 cm) was provided with a releasable heat resistant slipping layer on one surface and widths 10 cm and 14 cm on the opposite surface. A receiving layer and a dye layer were formed over the entire width of the film at intervals of. First, the receptive layer forming region of the substrate was coated with the following peeling layer forming ink with a gravure coater at a rate of 0.1 g / m ² when dried, and after temporary drying with a dryer. Formed at 100 ° C. for 2 minutes. Next, the following ink for forming a receiving layer is applied by gravure printing at a ratio of a thickness of 2.0 g / m ² when dried, and temporarily dried with a dryer, and then 100 ° C.
Formed in an oven for 2 minutes. Ink for forming release layer : Polyvinyl acetal resin (KS-1 manufactured by Sekisui Chemical Co., Ltd.) 10 parts Methyl ethyl ketone / toluene (1/1) 100 parts Receptor layer forming ink : Vinyl chloride / vinyl acetate copolymer (Union Carbide, VYHH) 100 parts Epoxy-modified silicone (Shin-Etsu Chemical Co., Ltd., KF-393) 3 parts Amino-modified silicone (Shin-Etsu Chemical Co., Ltd., KS-343) 3 parts Methyl ethyl ketone / toluene (1/1) 400 parts Subsequently, the ink having the following composition was applied to the surface of the receiving layer by a gravure coater at a rate of 3.0 g / m ² when dried, and tentatively dried with a dryer, then in an oven at 100 ° C. Formed by drying for 2 minutes. Ink for forming adhesive layer : Ethylene-vinyl acetate resin heat sealant 100 parts (Toyo Morton Co., Ltd., AD-37P295) Pure water 300 parts Next, a dye layer forming ink having the following composition was prepared and used as a base material. Adjacent to the area of the film where the receiving layer was formed, the dye layers were 10 cm each in the order of yellow, magenta, and cyan.
And a dry coating amount of 1.0 g / m ^{2 with} a gravure coater and dried to obtain a composite thermal transfer sheet of the present invention. Ink for forming dye layer : Polyvinyl acetoacetal resin (KS-5, manufactured by Sekisui Chemical Co., Ltd.) 1 part Dye XY part Methyl ethyl ketone / toluene (1/1) 20 parts * The following dye X was used . Yellow dye layer: C.I. I. Disperse Yellow 231 magenta dye layer: C.I. I. Disperse Violet 2
6 Cyan dye layer: C.I. I. Solvent Blue 63 Table 1 shows the D / B ratio (corresponding to Y part) of each dye layer in each example.

[0031]

[Table 1]

Comparative Examples 1 to 4 The transfer sheet of the present invention was obtained in the same manner as in Example 1 except that the conditions shown in Table 2 were used.

[0033]

[Table 2]

Using the above composite thermal transfer sheet, under the environment of 30 ° C. and 40 ° C., transfer of the receiving layer and overprinting of yellow, magenta and cyan dyes were carried out on a postcard manufactured by a public sector.
Black solid printing was performed. (Using Mitsubishi Electric Co., Ltd. video printer CP-11) The evaluation method was as follows. Density: Black solid printing was performed, and the density was measured with a Macbeth densitometer. Printing status: ○ ・ ・ ・ No defect △ ・ ・ ・ Sticking occurred (fine vertical stripes were generated on the printing screen surface due to defective peeling) × ・ ・ ・ Film did not peel off (printer stopped during cyan dye printing) The results are shown in Table 3.

[0035]

[Table 3]

[0036]

[Effect] By keeping the D / B ratio in the dye layer within a certain range as in the present invention, the releasability between the receiving layer and the dye layer at the time of dye printing is good, and the printing density is sufficient. A high composite thermal transfer sheet can be obtained. Furthermore, by setting the D / B ratio of the final color dye layer within a certain range, it is possible to sufficiently maintain the releasability even during printing in a high temperature environment.

Claims (3)

[Claims] 1. A composite thermal transfer sheet comprising a releasable receptive layer and a dye layer of at least one color provided in a surface-sequential manner on one surface of a substrate sheet, wherein a dye weight D in each of the dye layers is provided. And the ratio of the weight B of the dye binder is 0.5 <D / B <2.5. 2. The composite thermal transfer sheet according to claim 1, wherein D / B in the final color of the dye layer is 0.5 <D / B <2.0. 3. The D / B of the final color dye layer is smaller than the D / B of the dye layer before the final color dye layer.
The composite thermal transfer sheet according to claim 2.