JPH07304271A - Thermal image transfer sheet and image forming method - Google Patents

Abstract

PURPOSE:To provide a simple and convenient image forming method for transferring an image to a recording medium of any desired shape by using a thermosensitive sublimation transfer process, and a thermal image transfer sheet for use in the same method. CONSTITUTION:A thermal image transfer sheet 2 comprises a base sheet 21, a dye receiving layer 22, and a dye releasing layer 23 that contains a hydrophilic material and is provided between the base sheet 21 and the dye receiving sheet 22. A dye image is formed in the dye receiving layer 22. The thermal image transfer sheet 2 is then brought into contact with a recording medium with the dye receiving layer 22 facing the medium, and then the sheet 2 is heated to transfer the dye image to the recording medium. After that, the sheet 2 is removed from the recording medium.

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming an image on a material to be transferred using a heat-sensitive sublimation transfer system and a thermal transfer image-receiving sheet used as an intermediate medium.

[0002]

2. Description of the Related Art Conventionally, various image forming methods by thermal transfer have been known. A thermal transfer sheet having a dye carrier layer in which a sublimation dye is carried in a binder resin is provided on one side of a support. This thermal transfer sheet is formed by printing or coating an ink or coating liquid, which is a mixture of a binder resin and a sublimation dye, on a heat-resistant support, followed by drying. Then, the thermal transfer sheet is selectively heated from the back side by a printer having a heating means such as a thermal head, and an image is formed on the thermal transfer image receiving sheet having a dye-dyeable dye-receiving layer provided on the base sheet. . The formed dye image is clear and excellent in transparency because the coloring material used is a dye, and thus is excellent in halftone reproducibility and gradation. For this reason, 3 colors or 4
Suitable for reproducing full-color images formed by transferring a large number of color dots onto a thermal transfer image-receiving sheet, forming high-quality images equivalent to those produced by conventional offset printing or gravure printing, as well as full-color photographic images. is possible. For this reason, the thermal sublimation transfer system is useful and has been widely used in that it can easily obtain full-color hard copies of computer images and video images in an extremely short time.

[0003] However, due to the mechanism of the printer, it is very difficult to directly form the dye image obtained by the conventional method on a material other than a sheet-like thermal transfer receiving material such as a thermal transfer image receiving sheet. Therefore, attempts have been made to form a dye image using the above-described thermal transfer sheet on a transfer-receiving material of any shape other than a sheet-like thermal transfer-receiving material. for example,
JP-A-62-66997 and JP-A-60-203
Japanese Laid-Open Patent Publication No. 494 proposes a method of adhering a base sheet of a thermal transfer image-receiving sheet on which a dye image is formed to an object to be transferred like a label. However, in this method, there is a step corresponding to the thickness of the thermal transfer image-receiving sheet around the adhered portion, and there is a problem that the sheet is easily peeled off. Therefore, regarding the problem of the step difference, Japanese Patent Laid-Open No. 4-229292 discloses that a dye-receiving layer having a dye image formed thereon is peeled off from a substrate sheet of a thermal transfer image-receiving sheet, and the dye-receiving layer is brought into contact with a transfer material. A retransfer method has been proposed in which only the dye image is transferred by heating to a high temperature to transfer only the dye image to the transfer material, and then peeling off the dye receiving layer from the transfer material.
This method solves the step problem. However, in the method of JP-A-4-229292,
In addition to requiring a troublesome process of once peeling the dye-receiving layer from the base sheet of the thermal transfer image-receiving sheet and pressing it against the transfer-receiving material, such a peeling function is necessary for the base sheet and the dye-receiving layer. Due to restrictions on material selection for both materials and the need to handle only the peeled dye-receiving layer, the dye-receiving layer requires appropriate strength and thickness. There were also restrictions on selection. Furthermore, there is no particular limitation on the material of the thermal transfer sheet to be used,
It has been found that when a dye image is retransferred onto a transfer material using the described thermal transfer sheet, the dye may be discolored due to high temperature heating during retransfer. For this reason, the reproducibility of a full-color image, which is an excellent feature of the thermal sublimation transfer system, is remarkably impaired, and the color reproducibility of the original image is substantially impossible.

[0004]

SUMMARY OF THE INVENTION Accordingly, the present invention provides an image forming method by a simple re-transfer system which can be used together with the thermal transfer image-receiving sheet without peeling off the dye-receiving layer from the thermal transfer image-receiving sheet, and thermal transfer suitable for use therein. An object of the present invention is to provide an image receiving sheet.

[0005]

[Means for solving the problem]

<Summary of the Invention> In order to achieve the above object, the thermal transfer image-receiving sheet of the present invention comprises a base sheet and at least a dye-receiving layer provided thereon, wherein a hydrophilic substance is added between the base sheet and the dye-receiving layer. It is characterized in that it is provided with a dye-releasing layer containing the dye. In the image forming method of the present invention, a dye image is formed on the dye-receiving layer of the thermal transfer image-receiving sheet, and then the dye image is formed by bringing the dye-receiving layer side of the thermal transfer image-receiving sheet into contact with an object to be transferred and heating. is transferred to the transferred material, and then the thermal transfer image-receiving sheet is peeled off.

<Detailed Description of the Invention> Hereinafter, the image forming method of the present invention, which is a method for retransferring a dye image, will be described in detail with reference to the drawings. First, formation of a dye image on a thermal transfer image-receiving sheet using a thermal transfer sheet may be performed by a conventionally known method using a known thermal transfer printing apparatus such as a thermal printer or a video printer. FIG. 1 shows that a dye image 3 is formed on the sheet 2 by transferring the dye from the thermal transfer sheet 1 to the thermal transfer image receiving sheet 2 by means of a thermal transfer printing apparatus using a thermal head 5. Thus, a thermal transfer image-receiving sheet 2a is obtained as an intermediate medium on which the dye image 3 is formed as shown in FIG. Next, the dye image 3 is retransferred from the thermal transfer image receiving sheet 2a to the transfer receiving material. In FIG. 3, the thermal transfer image-receiving sheet 2a is being brought into contact with the outer surface of a mug cup 4, which is a ceramic beverage cup having a quadratic curved outer surface, as an object to be transferred. is shown. For retransfer, the side of the dye receiving layer of the thermal transfer image receiving sheet 2a to which the dye image 3 has been transferred is brought into contact with the transfer receiving surface of the transfer receiving material. As for the contact with the surface to be transferred, if there is a gap between it and the thermal transfer image-receiving sheet, the density of the obtained dye image is lowered and blurring is likely to occur. In short, it is sufficient that they are in such close contact that they do not float or shift during retransfer, and the pressure applied to the transfer surface of the thermal transfer image receiving sheet need not be large. As a means for maintaining close contact, it is preferable to press the thermal transfer image-receiving sheet against the transfer surface by applying force via an elastic body such as rubber having low adhesion to the transfer surface. Heating may be performed from the thermal transfer image receiving sheet side, from the transferred material side, or from both sides. When the object to be transferred is a cylindrical object such as a mug and the image is to be re-transferred onto its outer surface, a thermal transfer image-receiving sheet is applied to the outer surface portion to be transferred, the thermal transfer image-receiving sheet is covered with a rubber sheet, and then from the outside. It can be heated by covering the periphery with an arcuate heater and applying pressure.

[0007] The heating temperature and heating time for retransfer should be such that the dye molecules sufficiently migrate to the transfer-receiving material, and the thermal transfer image-receiving sheet is not fused to the transfer-receiving material, or the quality of the dye is deteriorated. The degree to which heat discoloration does not occur is added, but it varies depending on the heat resistance, heat capacity, etc. of the material to be transferred. For example, for transfer-receiving objects such as mugs illustrated in FIGS. 3 and 4, 1
Heat for about 10 minutes. After heating for the required time, the material to be transferred is air-cooled or water-cooled to a temperature near room temperature, and then the thermal transfer image-receiving sheet is peeled off from the material to be transferred. As described above, a dye image is formed on the transfer material. FIG. 4 shows a mug 4a onto which the dye image 3 has been retransferred and a thermal transfer image receiving sheet 2b from which the dye image has been removed.

The thermal transfer image-receiving sheet of the present invention will now be described in detail. FIG. 5 is a vertical cross-sectional view showing an example of a thermal transfer image-receiving sheet that can be used in the image forming method of the present invention. In FIG. It has a structure in which a dye-releasing layer 23 is interposed. Further, the thermal transfer image receiving sheet of the present invention may be provided with a back layer 24 on the back of the base sheet 21 as shown in FIG. The back layer can prevent adhesion to the elastic body when pressure is applied from the back side of the thermal transfer image-receiving sheet with an elastic body such as rubber during retransfer. Examples of the base sheet 21 used for the thermal transfer image receiving sheet 2 include synthetic papers such as polyolefin-based and polystyrene-based papers, coated papers such as art paper, coated paper, and cast-coated paper, glassine paper, condenser paper,
Thin paper such as paraffin paper, paper such as fine paper, polyester resin such as polyethylene terephthalate, polyethylene naphthalate, 1,4-polycyclohexylene dimethyl terephthalate, polycarbonate resin, cellophane, cellulose resin such as cellulose acetate,
Polyethylene, polypropylene, polystyrene, polyphenylene sulfide, polyvinyl chloride, polyvinylidene chloride, nylon, polyimide, polyvinyl alcohol,
Films such as resins such as fluororesins, chlorinated rubbers, ionomers, etc., or nonwoven fabrics, or, for example, laminates of papers and resin films, or composites in which resin is coated on paper, the above synthetic paper It may also be a composite of materials, papers, and resin films. Also, a sheet obtained by adding a white pigment or a filler to a resin to form a film to make it opaque white or foam it, and then providing a layer of the above-described resin thereon by a melt extrusion method or the like can also be used. A transparent or opaque base sheet can be used as the base sheet. The thickness of the base sheet is generally 30-300 µm, preferably 15 µm.
0 to 200 μm.

The dye-receiving layer 22 receives the thermally migratable dye transferred from the thermal transfer sheet 1 and retains the dye image.
It then serves as an intermediate medium for thermally transferring or releasing the received dye image to the final receiver. Although the dye-receiving layer 22 is required to have seemingly contradictory properties such as the receptivity and the releasability of the thermally migratable dye, basically, the temperature conditions for receiving the dye and the temperature conditions for releasing the dye, and By selecting materials such as dyes to be used and resins forming the dye-carrying layer and the dye-receiving layer of the thermal transfer sheet, even conventionally known resins forming the dye-receiving layer 22 can achieve the corresponding purpose. However, it is preferable to use a material that is less likely to fuse with the surface of the transfer-receiving material when transferred to the transfer-receiving material. Conventionally known thermoplastic resins can be used as the dye-receiving layer 22. Examples include polyolefin resins such as polypropylene, halogen-containing resins such as polyvinyl chloride and polyvinylidene chloride, polyvinyl acetate, ethylene-vinyl acetate Polymers, vinyl acetate resins such as vinyl chloride-vinyl acetate copolymers, polyvinyl acetal resins, acrylic resins such as (meth)acrylic acid esters, polystyrene resins such as polystyrene, olefin monomers such as ethylene and propylene and other vinyl monomers, polyester-based resins such as polyethylene terephthalate and polybutylene terephthalate, polycarbonate-based resins, cellulose-based resins such as cellulose acetate, polyamides, and ionomers. be.

[0010] In addition, thermosetting resins obtained by adding the following organosilicon compounds to the above thermoplastic resins or adding cross-linking agents are preferable because they are less likely to fuse with the material to be transferred. is. As the organosilicon compound to be used, reactive organosilicon compounds such as silicone oils containing functional groups such as amino groups, hydroxyl groups, mercapto groups, epoxy groups, isocyanate groups, carboxyl groups and vinyl groups are used as their precursors. First, there is an organosilicon compound as a graft polymer obtained by reacting a reactive organosilicon compound as the precursor with a reactive thermoplastic resin having a reactive functional group. Here, the reactive thermoplastic resin may be selected from the thermoplastic resin group described above as long as it has a reactive functional group. or,
In addition to the above organosilicon compounds, polyfunctional reactive compounds such as polyisocyanates and polyamines are used as cross-linking agents, and the reactive organosilicon compounds and the reactive thermoplastic resins having functional groups capable of reacting with these are combined. It may be an organosilicon compound obtained by reacting to form a graft polymer. Alternatively, it may be an organosilicon compound obtained as a graft polymer by copolymerizing a reactive organosilicon compound such as silicone oil having a vinyl group with a general monomer having a vinyl group, an acryloyl group, or the like. When the organosilicon compound thus obtained is added to the resin constituting the dye-receiving layer, the branch polymer portion composed of the grafted reactive organosilicon compound is distributed on the surface of the dye-receiving layer, while The backbone polymer portion composed of a reactive thermoplastic resin is compatible with the resin forming the dye-receiving layer. It is also possible to impart an effect of preventing fusion with a transfer-receiving material during re-transfer. The amount of these organosilicon compounds added is preferably in the range of 1 to 50 parts by weight per 100 parts by weight of the resin constituting the dye-receiving layer. If the amount added is too small, oil repellency and slip properties will be insufficient, and desired anti-fingerprint, anti-plasticizer and anti-scratch properties will not be obtained. On the other hand, if the amount added is too large, the migration of the dye from the thermal transfer sheet will be insufficient, making it impossible to obtain a high-density transferred image and lowering the film strength of the dye-receiving layer.
I don't like it.

On the other hand, as a cross-linking agent for cross-linking a thermoplastic resin, a polyisocyanate compound, a polyepoxide compound having an epoxy group, a polyamine compound, and the following formula 7
and chelate compounds, alcoholates, ester gums, etc., and chelate compounds are particularly preferred. (R1 _- O) _m -M(X) _n formula 7 formula 7, M: metal atom (titanium, aluminum, zirconium) _R1 : alkyl group, aryl group, hydrogen, etc. m+n=3 or 4 X: glycol, Represents β-diketone, hydroxycarboxylic acid, ketoester, ketoalcohol. The following (1) to (5) exemplify the coordination modes to the metal atom M. In addition, R ₂ to R
₉ is an alkyl group, an aryl group, hydrogen, or the like.

[Chemical 1] The amount of the cross-linking agent used is appropriately adjusted depending on the type of reactive thermoplastic resin having reactivity with the cross-linking agent, the number of functional groups, the molecular weight of the cross-linking agent, the number of functional groups, and the like. About 20 parts by weight is preferable. The use of a cross-linking agent has the effect of preventing the thermal transfer image-receiving sheet from fusing to the transfer material.

[0012] The dye-receiving layer 22 may be provided on the substrate sheet 21 by a conventionally known method. That is, by adding the thermoplastic resin described above, an organic silicon compound and a cross-linking agent as necessary, and other optional additives,
These are dissolved or dispersed in a suitable solvent to prepare a coating solution or ink for forming a dye-receiving layer, which is applied onto a substrate sheet by a known coating method or printing method to dry the solvent component, and If a cross-linking agent is used as necessary, it may be cured by heating. The thickness of the dye-receiving layer 22 thus formed is 1 to 10 µm, preferably 2 µm.
It has a thickness of about 5 μm.

As shown in FIGS. 5 and 6, the thermal transfer image-receiving sheet of the present invention is provided with a dye release layer 23 between the substrate sheet 21 and the thermal transfer image-receiving layer 22 . The dye-releasing layer 23 promotes transfer of the dye image transferred to the thermal transfer image-receiving sheet to the transferred material. The dye-releasing layer 23 is a layer containing a hydrophilic substance and having low dye-diffusibility. Specific examples of hydrophilic substances include seaweed extracts such as agar and sodium alginate, plant viscous substances such as gum arabic and tororo mallow, animal proteins such as casein and gelatin, fermented viscous substances such as pullulan and dextran, starch and starch. quality, methyl cellulose and carboxymethyl cellulose,
Cellulosic substances such as hydroxyethyl cellulose, polyvinylpyrrolidone, polyvinyl ether, polymaleic acid copolymers, polar group-containing acrylic copolymers, synthetic polymers such as polyvinyl alcohol, and inorganic polymers such as sodium polyphosphate. Among them, particularly suitable substances are polyvinylpyrrolidone-based resins and alkyl vinyl ether/maleic anhydride copolymer resins. Excellent adhesion to the dye-receiving layer,
Furthermore, since the formed film has high strength and excellent heat resistance, the dye-receiving layer is not peeled off from the base sheet when forming an image on the thermal transfer image-receiving sheet or when re-transferring the image to a transfer-receiving material. It is possible to prevent the thermal transfer image-receiving sheet from being thermally fused to the dye transfer film or the material to be transferred. In addition, polyvinylpyrrolidone-based resins and alkyl vinyl ether/maleic anhydride copolymer resins are
While being water-soluble, it is also highly soluble in organic solvents such as alcohol solvents such as ethyl alcohol and isopropyl alcohol, and ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, which have relatively low boiling points and are easy to remove by drying. It is a substance and has high compatibility with many resins soluble in organic solvents, which is the reason why it has high adhesiveness with many organic and inorganic substances.

In the resin forming the dye-releasing layer and the resin forming the dye-receiving layer, various additives are optionally added for the purpose of improving whiteness, strength and hardness, and light resistance. may be included. If the degree of whiteness is improved, the quality of the dye image formed on the thermal transfer image-receiving sheet can be judged at the stage of the intermediate image, and it can be judged whether the image should be transferred to the final transfer material. Examples of additives include inorganic fillers such as silica, alumina, clay, talc, calcium carbonate, barium sulfate, white pigments such as titanium oxide and zinc oxide, acrylic resins, epoxy resins, polyurethane resins, phenol resins, and melamine resins. , fillers such as resin particles or fine particles such as benzoguanamine resin, fluororesin, and silicone resin, fluorescent whitening agents, ultraviolet absorbers, antioxidants, and the like. Additives are added in an amount of 10 to 30 parts by weight per 100 parts by weight of the resin forming the dye-releasing layer.
It is in the range of 0 parts by weight, and in the case of a fluorescent whitening agent, a small amount may be sufficient. In addition to the above resins forming the dye-releasing layer, other resins may be mixed and used, if necessary, for the purpose of improving the adhesion between the base sheet and the dye-receiving layer within the scope of the purpose. .

The dye release layer 23 may be provided on the base sheet 21 by a conventionally known coating film forming method.
That is, the above resins and other optional additive components are added, and these are mixed with methanol, isopropyl alcohol,
A coating liquid or ink for forming a dye-releasing layer is prepared by dissolving or dispersing it in a suitable solvent such as water, acetone, methyl ethyl ketone, ethyl acetate, toluene, xylene, cyclohexanone, and the like, and is subjected to a known coating method or printing method, for example. , gravure coating, reverse roll coating, gravure reverse roll coating, gravure printing, screen printing, or the like, and the solvent component is dried. The thickness of the dye-releasing layer 23 thus formed is 0.05-5, preferably 0.1-3.
It has a thickness of about μm. If the thickness is too thin, the density of the retransferred image may decrease, or the adhesion to the base sheet may decrease.
Problems such as peeling of the dye-receiving layer may occur, and if the thickness is too thick, it is uneconomical.

The interposition of the dye release layer between the base sheet and the dye image receiving layer of the thermal transfer image receiving sheet facilitates the transfer of the dye image transferred and formed in the dye image receiving layer in the retransfer process to the transfer receiving material. be done. Although the details of this mechanism are unknown, it is presumed as follows. First, the affinity between the dye and the dye-releasing layer is poor because the dye-releasing layer is composed of a hydrophilic substance and the dye is water-insoluble. Therefore, the dye-releasing layer acts as a barrier layer on the back side, and suppresses the diffusive movement of the dye molecules toward the back side during retransfer, thereby promoting the diffusive movement toward the transferred material. Second, the dye-releasing layer has a higher hygroscopicity than other layers. Therefore, moisture that is equilibrated in the dye-releasing layer under normal use diffuses into the dye-receiving layer during the retransfer process. At this time, since the affinity between the water-insoluble dye and water is poor, a repulsive force acts, and the water acts like a plasticizer on the resin of the dye-receiving layer, causing diffusion of the dye molecules in the dye-receiving layer. Increase speed. Due to the action of the dye release layer as described above, the density of the dye image formed on the transfer material is improved. In addition, the heat and time required for retransfer are reduced by promoting dye transfer, and as a result, the amount of diffusion movement of dye molecules in the lateral direction in both the dye-receiving layer and the layer on which the dye image is formed on the transfer material is reduced in the vertical direction. It is considered that the blurring of the image is reduced because the diffusion movement amount is decreased relative to the diffusion movement amount. Moreover, as a result of the reduction in the heat and time required for retransfer, the dye-receiving layer of the thermal transfer image-receiving sheet is less likely to fuse to the transfer-receiving material.

When the back layer 24 is provided on the thermal transfer image receiving sheet, acrylic resin, polyvinyl acetal resin such as polyvinyl acetoacetal, polyvinyl butyral,
Cellulose resins, polyimide resins, polyaramid resins, etc. can be used, but in order to prevent the thermal transfer image-receiving sheet from deteriorating due to heat when the image is re-transferred to the transfer receiving material, a back layer is formed. The glass transition temperature of the resin is desirably 160° C. or higher, particularly preferably 180° C. or higher, and cellulose-based resins such as cellulose acetate resins, polyimide resins, and the like are suitable. In addition, the back layer contains inorganic fillers such as silica and talc, fluorine resins such as Teflon, resin fine particles such as silicone and polyamide resins,
Waxes such as polyethylene wax and carnauba wax, lubricants such as modified silicone oil, and the like may be added. The thermal transfer image-receiving sheet of the present invention is used as an intermediate medium in the method of the present invention in which a dye image is once transferred from the thermal transfer sheet and the dye image is transferred again to the final receiving material. . However, the thermal transfer image-receiving sheet itself may be used not as an intermediate medium but as a final transfer material.

[0018] Next, the object to be transferred in the image forming method by retransfer of the present invention will be described. Unlike the thermal transfer image-receiving sheet described above in which a dye image is formed by a printer, the transfer-receiving material is not restricted by the mechanism of the printer. Mechanical restrictions include the thickness, size, heat capacity, external shape, etc. of the object to be transferred. As a result, all transferred objects having arbitrary shapes can be targeted. For example, pottery, porcelain, enamel, metal, as specifically shown in FIG.
A cup such as a drinking mug made of plastic or the like can be mentioned. The advantage of the retransfer method using the thermal transfer image-receiving sheet as an intermediate medium is that a dye image can be formed even on such a transfer receiving material having a curved surface. Further, as the material of the object to be transferred, any material can be used, such as ceramics, porcelain as described above, ceramics such as glass, metal, enamel, plastic, and the like. In addition, the above-mentioned cup shape is an example, and other shapes include thin and thick plates such as glass plates, plastic plates, tiles, and metal plates, columnar shapes, polygonal columnar shapes, curved shapes, and the like. good too. Alternatively, it may be in the form of a thin sheet such as a thermal transfer image receiving sheet. As described above, the material to be transferred is not limited in terms of shape and material, but materials such as glass, ceramics, or even plastic can be used to ensure or improve the receptivity of the dye image from the thermal transfer image-receiving sheet, thereby producing a high-density image. For the purpose of obtaining an image, it is preferable to form a surface layer of a specific resin having dyeability on the surface of the material to be transferred. As such a resin, a resin mainly composed of an epoxy resin, a modified epoxy resin, or the like is preferable. Examples thereof include bisphenol A-type epoxy resin, bisphenol S-type epoxy resin, phenol novolac-type epoxy resin, cresol novolac-type epoxy resin, brominated epoxy resin, and styrene-modified epoxy resin. These resins are cured using, for example, amine compounds, acid anhydride compounds, phenolic resins, amino resins, mercaptan compounds, dicyandiamide, and Lewis acid complex compounds as curing agents. The thickness of the resin surface layer formed on the surface of the material to be transferred should be sufficient to receive the dye.
Generally, it is about 0.5-20 micrometers. In addition, it is sufficient that such a resin layer is formed on at least the transfer surface of the transferred body.

Next, the dye used as the dye image to be formed on the material to be transferred will be described. As such dyes,
It is a thermally migratable dye that sublimates or diffuses by heat and migrates from a dye donor such as a thermal transfer image receiving sheet to a transfer material, and is not particularly limited as long as it has light resistance, dyeability to the transfer material, and the like. However, if the object to be transferred is a drink cup, naturally water-insoluble dyes are suitable. Disperse dyes and oil-soluble dyes are preferably used. Further, since the temperature and time conditions for retransfer can be relaxed due to the effect of the dye-releasing layer of the thermal transfer image-receiving sheet, the range of dyes that can be used is wider than before. These dyes are
For example, diarylmethanes, triarylmethanes, thiazoles, methines such as merocyanine, indoaniline, acetophenone azomethine, pyrazoloazomethine,
Azomethines represented by imidazolazomethine, imidazoazomethine, pyridoneazomethine, xanthenes,
Oxazine, dicyanostyrene, cyanomethylene represented by tricyanostyrene, thiazine, azine, acridine, benzeneazo, pyridoneazo, thiophenazo, isothiazoleazo, pyrroleazo, pyrazoleazo, imidazoleazo, thiadiazoleazo, triazole Azo compounds such as azo and disazo, spiropyran compounds, indolinospiropyran compounds, fluoran compounds, rhodamine lactam compounds, naphthoquinone compounds, anthraquinone compounds, quinophthalone compounds, and the like. Specific examples include the following dyes. C. I. (Color Index) Disperse Yellow 51,
3, 54, 79, 60, 23, 7, 141, 201, 2
31C. I. Disperse Blue 24,56,14,30
1,334,165,19,72,87,287,15
4,26,354 C.I. I. disperse threads 135, 146, 59,
1,73,60,167 C.I. I. Disperse Violet 4, 13, 26, 3
6, 56, 31 C.I. I. Disperse Orange 149 C.I. I. Solvent Yellow 56, 14, 16, 29 C.I. I. Solvent Blue 70, 35, 63, 36, 5
0, 49, 111, 105, 97, 11 C.I. I. Solvent Red 135, 81, 18, 25,
19, 23, 24, 143, 146, 182 C.I. I. solvent violet 13, C.I. I. Solvent Black 3, C.I. I. Solvent green 3

More specifically, for example, Kayaset Blue 714 (Solvent Blue 63 manufactured by Nippon Kayaku Co., Ltd.) and Foron Brilliant Blue S-R are used as cyan dyes.
(Sando, Disperse Blue 354), Waxolin AP-FW (ICI, Solvent Blue 36), MS-REDG as a magenta dye (Mitsui Toatsu, Disperse Red 60), Macrolex Red Violet R (Bayer, Disperse Blue) Perth Violet 26), Foron Brilliant Yellow S-6 as a yellow dye
GL (Disperse Yellow 231, manufactured by Sandoz), Macrolex Yellow 6G (Disperse Yellow 201, manufactured by Bayer), and those having the skeleton shown below.

[Chemical 2]

Also, JP-A-59-78895 and JP-A-60-
28451, 60-28453, 60-535
No. 64, No. 61-148096, No. 60-28929
No. 0, No. 60-31565, No. 60-30393,
No. 60-53565, No. 60-27594, No. 61
-262191, 60-152563, 61-
sublimation yellow dyes described in 244595 and 62-196186 and WO 92/05032;
No. 60-223862, No. 60-28452, No. 6
No. 0-31563, No. 59-78896, No. 60-3
1564, 60-30391, 61-2270
92, 61-227091, 60-30392
No. 60-30394, No. 60-131293,
No. 61-227093, No. 60-159091, No. 61-262190, U.S. Pat.
Sublimable magenta dyes described in JP-A-9365, JP-A-59
-78894, 59-227490, 60-1
51098, 59-227493, 61-24
4594, 59-227948, 60-131
No. 292, No. 60-172591, No. 60-1510
97, 60-131294, 60-21726
No. 6, No. 60-31559, No. 60-53563,
No. 61-255897, No. 60-239289, No. 61-22993, No. 61-19396, No. 61-
268493, 61-35994, 61-31
467, 61-148269, 61-4989
No. 3, No. 61-57651, No. 60-239291
No. 60-239292, 61-284489
No. 62-191191 and Japanese Patent Application No. 62-17
Sublimation cyan dyes described in publications and specifications such as US Pat. No. 6,625 and US Pat.
Among them, preferred dyes are exemplified by the following general formulas.

[0022]

[Chemical 3]

[Chemical 4]

[Chemical 5]

[Chemical 6]

In the general formula above, R, X and Y represent the following substituents. R ₁ and R ₂ substituted or unsubstituted alkyl group, substituted or unsubstituted cycloalkyl group, or substituted or unsubstituted aralkyl group. R ₃ substituted or unsubstituted alkyl group, substituted or unsubstituted alkoxy group, substituted or unsubstituted alkylcarbonylamino group, substituted or unsubstituted alkylsulfonylamino group, substituted or unsubstituted alkylaminocarbonyl group, substituted or unsubstituted alkylaminosulfonyl group or halogen atom; R ₄ substituted or unsubstituted alkoxycarbonyl group, substituted or unsubstituted alkylaminocarbonyl group, substituted or unsubstituted alkoxy group, substituted or unsubstituted alkyl group, substituted or unsubstituted cycloalkyl group, heterocyclic group, or a halogen atom. R ₅ substituted or unsubstituted alkyl group, substituted or unsubstituted alkoxycarbonyl group, substituted or unsubstituted alkylaminocarbonyl group, substituted or unsubstituted alkoxy group, substituted or unsubstituted alkylaminosulfonyl group, substituted or unsubstituted A substituted cycloalkyl group, cyano group, nitro group, halogen atom, or hydrogen atom. _R6 substituted or unsubstituted alkyl group, substituted or unsubstituted aryl group, substituted or unsubstituted amino group, substituted or unsubstituted cycloalkyl group, cyano group, nitro group, or halogen atom. _R7 substituted or unsubstituted alkyl group, substituted or unsubstituted amino group, substituted or unsubstituted alkoxy group, substituted or unsubstituted alkoxycarbonyl group, or halogen atom. _R8 substituted or unsubstituted aryl group, aromatic heterocyclic group, cyano group, nitro group, halogen atom, or other electron-withdrawing group. _R9CONHR10 , _SO2NHR10 , _{NHCOR11 , NHS
O2R11} , or a _halogen atom. R ₁₀ substituted or unsubstituted alkyl group, substituted or unsubstituted cycloalkyl group, substituted or unsubstituted aryl group, or substituted or unsubstituted aromatic heterocyclic group. R ₁₁ substituted or unsubstituted alkyl group, substituted or unsubstituted cycloalkyl group, substituted or unsubstituted amino group, substituted or unsubstituted aryl group, or substituted or unsubstituted aromatic heterocyclic group. R ₁₂ substituted or unsubstituted alkyl group. R ₁₃ amino group or hydroxyl group. X halogen atom. Y A substituted or unsubstituted aryl group or a substituted or unsubstituted aromatic heterocyclic group.

The dyes that can be used may be those described above, but the dyes of the following formulas 1 to 6 are particularly excellent in heat resistance.
It is suitable for a method of forming a dye image by retransfer.

[Chemical 7]

[Chemical 8] Equations 1 and 2 indicate the hue of yellow, Equations 3, 4 and 5 indicate the hue of magenta, and Equation 6 indicates the hue of cyan. These dyes may be used alone, but it is preferable to use a mixture of dyes for magenta. Formulas 4 and 5 are excellent in heat resistance, but the density may become low during retransfer, and when formula 3 is used in combination, a high density retransferred image can be obtained by suppressing the decrease in density. In addition, mainly using the dyes of formulas 1 to 6,
If necessary, there is also a method of using the dyes described above together for hue adjustment. As the thermal transfer sheet to be used in the image forming method of the present invention, if a thermal transfer sheet containing the dyes of formulas 1 to 6 is used, it is possible to obtain a transfer material exhibiting more excellent color reproducibility. , a conventionally known thermal transfer sheet can be used.

For example, such a thermal transfer sheet comprises at least a support 11 and a dye carrying layer 12, as shown in FIG. The support 11 may be any material as long as it has heat resistance and strength that can withstand the heat during thermal transfer. resin, cellophane, cellulose resin such as cellulose acetate,
Polyethylene, polypropylene, polystyrene, polyphenylene sulfide, polyvinyl chloride, polyvinylidene chloride, nylon, polyimide, polyvinyl alcohol,
Films such as resins such as fluororesins, chlorinated rubbers and ionomers can be used. Papers such as condenser paper and paraffin paper, non-woven fabrics, etc., or composites of these and the above resins may also be used. Common among these is polyethylene terephthalate film. The thickness of the support 11 may be appropriately selected according to the application and material so that its mechanical strength, thermal conductivity, etc. are appropriate.
Generally, for example, about 1.5 to 50 μm, preferably 2
˜10 μm.

The dye-carrying layer 12 is made by dissolving or dispersing the above-described heat-migration dye in an arbitrary binder resin, which sublimates or diffuses when heated and migrates to the material to be transferred. layer. As a binder resin,
A conventionally known one can be used. The properties to be possessed by such a binder resin include that it has a suitable affinity for the dye, and that the dye in the binder resin is sublimated or diffused by heating with a heating means such as a thermal head to form a material to be transferred. Also, when the dye-carrying layer is exposed, the binder resin itself does not fuse or transfer to the transfer material even if it is heated. . Examples of such binder resins include cellulose resins such as ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, cellulose nitrate, cellulose acetate, and cellulose acetate/butyrate.
Polyvinyl acetal resins such as polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, and polyvinyl acetoacetal; vinyl resins such as polyacrylamide and polyvinylpyrrolidone; and resins such as polyesters, polyamides and maleic anhydride copolymer resins. These resins are used singly or as a mixture.
Among these, it is particularly preferable to use binder resins mainly composed of polyvinyl acetal resins such as polyvinyl butyral and polyvinyl acetoacetal from the viewpoint of heat resistance and dye transferability.

As the dye contained in the dye-carrying layer 12, the various dyes described above, particularly preferably the dyes represented by the formulas 1 to 6 are used. These dyes may be used alone, or may be used in combination as necessary. Generally, a thermal transfer sheet for a full-color image uses three color dyes of yellow, magenta, and cyan, and further uses four color dyes by adding black as necessary. In the thermal transfer sheet, the dye-carrying layer 12 having a plurality of color components is generally formed on a continuous support 11 in a frame-sequential manner, and the order in which the dye-bearing layers are arranged in a frame-sequential manner is arbitrary. Alternatively, the purpose can be achieved by using a plurality of monochromatic thermal transfer sheets independent of each other. The proportion of the dye contained in the dye-carrying layer 12 is appropriately adjusted depending on the sublimation (or melting) temperature, dye transferability, etc., but usually 5% of the total weight of the dye-carrying layer.
~75% by weight, preferably 10-60% by weight. 5
If the amount is less than 75% by weight, the printing density and thermal sensitivity of the thermal transfer image-receiving sheet will be reduced.
A conventionally known method may be used to provide the dye-carrying layer 12 on the support 11 . That is, dyes, binder resins and other optional additive components are added, these are dissolved or dispersed in a suitable solvent to prepare a coating solution or ink for forming a dye-carrying layer, and this is applied by a known coating method or printing method. It may be applied onto a support by a method and the solvent component may be dried. The thickness of the dye-carrying layer 12 thus formed is
The thickness is about 0.2 to 5.0 μm, preferably about 0.4 to 2.0 μm.

The thermal transfer sheet used in the image forming method of the present invention may have a structure in which a lubricating layer 13 is provided on the rear surface of the thermal transfer sheet 1 as shown in FIG. moreover,
Dye-carrying layer 12 and support 11, slipping layer 13 and support 11
In order to improve the adhesion of the substrate 11, the support 11 may be subjected to a known easy-adhesion treatment such as corona discharge treatment or installation of an anchor layer. These easy-adhesion treatments are used singly or in any combination. Although not shown, there is also a construction in which an anti-adhesion layer is further provided on the surface of the dye-carrying layer. The lubricating layer 13 is for preventing fusion with the thermal head that contacts the back surface of the thermal transfer sheet during thermal transfer and for improving slippage. , silicone resins, or reaction products of isocyanate with active hydrogen-containing resins such as polyvinyl butyral and polyvinyl acetoacetal, and if necessary, additives such as known antistatic agents, lubricants and fillers are added. A layer having a thickness of about 0.5 to 5 μm, preferably about 1 to 2 μm is provided.

The anti-adhesion layer prevents fusion between the thermal transfer sheet and a material to be transferred such as a thermal transfer image-receiving sheet during thermal transfer. Furthermore, a layer made of a releasing resin having excellent releasing properties such as silicon resin, acrylic resin, and fluorine-containing resin has a thickness of about 0.01 to 5 µm, preferably about 0.05 to 2 µm. It is set by
Alternatively, the binder resin may be mixed with the above anti-tacky releasing resin, or fine particles thereof or inorganic fine particles may be mixed and contained in the dye-carrying layer. It is also possible to use a releasable binder resin obtained by graft-polymerizing a releasable segment such as a polysiloxane segment to the binder resin described above. The form of the thermal transfer sheet that can be used in the image forming method of the present invention may be a sheet cut to a required size, a continuous sheet, a roll, or a narrower sheet. It may be ribbon-shaped.

[0030]

EXAMPLES The present invention will now be described in more detail with reference to examples and comparative examples. In addition, "part" in the description of the examples
"Parts by weight" means parts by weight. Example 1 As a base sheet, a synthetic paper (Oji Oil ^Chemical Synthetic Paper (manufactured by FPU-60, Co., Ltd.) was laminated by a conventional dry lamination method, and a coating solution for forming a dye-releasing layer having the following composition was applied to one side of the laminated sheet as a dye-releasing layer in a dry amount of 0.7 g. /m ² , and dried. Then, as a dye-receiving layer, a coating solution for forming a dye-receiving layer having the following composition was applied in the same manner so that the dry coating amount was 1.5 g/m ² . and dried to obtain a thermal transfer image-receiving sheet of the present invention. Coating solution for forming dye release layer Polyvinyl pyrrolidone resin 10 parts (PVP K-90 manufactured by ISP) Isopropyl alcohol 90 parts Coating solution for forming dye receiving layer Vinyl chloride-vinyl acetate copolymer 20 parts (manufactured by Denki Kagaku Kogyo Co., Ltd.) #1000A) Amino-modified silicone 4 parts (Shin-Etsu Chemical Co., Ltd. KF-393) Epoxy-modified silicone 4 parts (Shin-Etsu Chemical Co., Ltd. X-22-343) Toluene 40 parts Methyl ethyl ketone 40 parts

Example 2 A thermal transfer image-receiving sheet was obtained in the same manner as in Example 1 except that the following coating solution was used as the coating solution for forming the dye release layer. Coating liquid for forming dye-releasing layer Methyl vinyl ether/maleic anhydride copolymer 10 parts (Gantrez AN-169 manufactured by ISP) Isopropyl alcohol 20 parts Water 70 parts

Example 3 A thermal transfer image-receiving sheet was obtained in the same manner as in Example 1 except that the following coating solution was used as the coating solution for forming the dye-releasing layer. Coating liquid for forming dye-releasing layer Water-soluble acrylic resin 10 parts (Julymer SP-65T manufactured by Nippon Junyaku Co., Ltd.) Isopropyl alcohol 20 parts Water 70 parts

Example 4 A thermal transfer image-receiving sheet was obtained in the same manner as in Example 1 except that the following coating solution was used as the coating solution for forming the dye-releasing layer. Coating liquid for forming dye-releasing layer Cellulose-based water-soluble resin 10 parts (HEC SP-200 manufactured by Daicel Chemical Industries, Ltd.) Isopropyl alcohol 10 parts Water 80 parts

Example 5 A thermal transfer image-receiving sheet was prepared in the same manner as in Example 1, except that the following coating solution was coated on the opposite side of the dye-receiving layer so that the dry coating amount was 1.5 g/m ² . Obtained. Coating liquid for forming heat-resistant back layer Cellulose acetate resin 5 parts (L-70 manufactured by Daicel Chemical Industries, Ltd.) Methyl ethyl ketone 70 parts Methyl isobutyl ketone 25 parts

Comparative Example 1 A thermal transfer image-receiving sheet was obtained in the same manner as in Example 1, except that a primer layer having the composition shown below was used in place of the dye-releasing layer and the dry coating amount was 0.7 g/m ² . Coating liquid for forming primer layer Urethane resin 10 parts (N-5137 manufactured by Nippon Polyurethane Industry Co., Ltd.) Methyl ethyl ketone 45 parts Toluene 45 parts

Comparative Example 2 A thermal transfer image-receiving sheet was obtained in the same manner as in Example 1 except that a primer layer having the composition shown below was used in place of the dye-releasing layer and the dry coating amount was 0.7 g/m ² . Coating liquid for primer layer formation Polyester resin 10 parts (Vylon 200 manufactured by Toyobo Co., Ltd.) Methyl ethyl ketone 45 parts Toluene 45 parts

<Thermal Transfer Sheet> Thermal transfer sheet A As a support, a polyethylene terephthalate film having a thickness of 6 μm and having a heat-resistant back surface was used. A thermal transfer sheet A was obtained by coating and drying by a gravure coating method so that the amount was 1.0 g/m ² . Note that the thermal transfer sheets coated with the respective colors were joined together in a frame-sequential manner. Coating solution for forming dye-carrying layer (A) Yellow component 3.2 parts of dye of formula 2 Dye of formula (i) below 4.8 parts Polyvinyl acetoacetal resin 3.5 parts (KS-5 manufactured by Sekisui Chemical Co., Ltd.) ) Solvent 70 parts (Toluene / methyl ethyl ketone = 1/1) (B) Magenta component Dye of the following formula (ii) 2.6 parts Dye of formula 4 3.4 parts Dye of formula 5 2.3 parts Polyvinylacetoacetal resin 3 .5 parts (KS-5 manufactured by Sekisui Chemical Co., Ltd.) Solvent 70 parts (Toluene/methyl ethyl ketone = 1/1) (C) Cyan component Dye of formula (iii) below 3.1 parts Dye of formula (iv) below 1.5 parts Dye of Formula 6 3.1 parts Polyvinylacetoacetal resin 3.5 parts (KS-5 manufactured by Sekisui Chemical Co., Ltd.) Solvent 70 parts (toluene/methyl ethyl ketone = 1/1)

[0038]

[Chemical 9] <Transfer Material> A commercially available ceramic mug was immersed in the liquid of the following resin composition and cured by heating at 150° C. for 10 minutes to form an epoxy resin layer having a thickness of 10 μm on the outer surface. Bisphenol A type epoxy resin 100 parts (Epikote YD8125 manufactured by Tohto Kasei Co., Ltd.) Polyamide curing agent 25 parts (Goodmide G700 manufactured by Tohto Kasei Co., Ltd.)

<Image formation on a mug> Using the thermal transfer sheet and the thermal transfer image-receiving sheet obtained in the above example, a video printer (VY-20 manufactured by Hitachi, Ltd.) was used.
0) transferred the dye image onto the receiving sheet. Here, a 16-step gray scale was used as the original image for transfer. Next, the thermal transfer image-receiving sheet having the dye image transferred thereon was pressed against the above mug and heated at 140° C. for 2 minutes and 17 minutes.
The dye image was retransferred by heating and pressing for 2 minutes at 0°C.

<Evaluation of Transferred Image> The density of the darkest color portion (16th row) of the grayscale image retransferred to the mug cup of the transferred object was measured using a reflection densitometer RD-918 manufactured by Macbeth Co., Ltd. measured in Table 1 shows the results.

[Table 1]

Example 6 As a base sheet, a 1:1 mixture of medium-density polyethylene and low-density polyethylene was applied to both sides of the core of coated paper (manufactured by Shin-Oji Paper Co., Ltd., Satin Kinfuji, basis weight: 84.9 g/m ² ). A resin-coated paper coated with a mixture to a thickness of 30 μm on both sides by a melt extrusion method was used.
m ² by bar coating and drying, then, as a dye-receiving layer, a coating solution for forming a dye-receiving layer having the following composition is coated in the same manner so that the dry coating amount is 3 g/m ² ,
After drying, a thermal transfer image-receiving sheet was obtained. Acrylic resin containing polar group (antistatic resin) 20 parts (Julymar SP-65T manufactured by Nippon Junyaku Co., Ltd.) Isopropyl alcohol 80 parts Coating solution for forming dye-receiving layer Vinyl chloride-vinyl acetate- Vinyl alcohol copolymer 50 parts (#1000GK manufactured by Denki Kagaku Kogyo Co., Ltd.) Polyester resin 50 parts (Vylon 600 manufactured by Toyobo Co., Ltd.) Titanate-based chelating agent 10 parts [(C ₃ H ₇ O) ₂ Ti(C ₅ H ₇ O ₂ ) ₂ ] Epoxy-modified silicone 5 parts (Shin-Etsu Chemical Co., Ltd. X-22-343) Methyl ethyl ketone/toluene (1:1) 400 parts

Example 7 Example 6 except that the coating solution for forming the dye-releasing layer was as follows.
A thermal transfer image-receiving sheet was obtained in the same manner as above. Coating liquid for forming a dye-releasing layer Polar group-containing acrylic resin (antistatic resin) 50 parts (Elekondo PQ-50B manufactured by Soken Chemical Co., Ltd.) Methanol 20 parts

Example 8 Example 6 except that the following dye-releasing layer-forming coating solution was used.
A thermal transfer image-receiving sheet was obtained in the same manner as above. Coating liquid for forming the dye-releasing layer Polar group-containing acrylic resin (antistatic resin) 10.0 parts (Julymer SP-65T manufactured by Nippon Junyaku Co., Ltd.) Polyvinyl alcohol 3.4 parts (Gosenol manufactured by Nippon Synthetic Chemical Co., Ltd.) C-500) Isopropyl alcohol 40.0 parts Water 46.6 parts

Example 9 Example 6 except that the following dye-releasing layer-forming coating solution was used.
A thermal transfer image-receiving sheet was obtained in the same manner as above. Coating liquid for forming dye-releasing layer Polyvinyl alcohol 6.8 parts (Gosenol C-500 manufactured by Nippon Synthetic Chemical Co., Ltd.) Water 93.2 parts

Example 10 Example 6 except that the dye-receiving layer-forming coating solution was as follows.
A thermal transfer image-receiving sheet was obtained in the same manner as above. Vinyl chloride-vinyl acetate copolymer 50 parts (# 1000GK manufactured by Denki Kagaku Kogyo Co., Ltd.) Polyester resin 50 parts (Vylon 200 manufactured by Toyobo Co., Ltd.) Epoxy-modified silicone 5 parts (Shin-Etsu Chemical Co., Ltd.) Kogyo Co., Ltd. X-22-343) Methyl ethyl ketone/toluene (1:1) 400 parts

Comparative Example 3 A thermal transfer image-receiving sheet was obtained in the same manner as in Example 6, except that no dye-releasing layer was provided.

Comparative Example 4 Example 6 except that the following dye-releasing layer-forming coating solution was used.
A thermal transfer image-receiving sheet was obtained in the same manner as above. Coating liquid for forming a dye release layer Polyester resin 20 parts (Vylon 200 manufactured by Toyobo Co., Ltd.) Methyl ethyl ketone/toluene (1:1) 80 parts

<Thermal transfer sheet> Thermal transfer sheet B As a support, a polyethylene terephthalate film having a thickness of 6 µm and having a heat-resistant back surface was used. A thermal transfer sheet B was obtained by coating and drying by a gravure coating method so that the amount was 1.0 g/m ² . Note that the thermal transfer sheets coated with the respective colors were joined together in a frame-sequential manner. Coating solution for forming dye-carrying layer (A) Yellow component Dye of Formula 1 3 parts Polyvinylacetoacetal resin 4.5 parts (KS-5 manufactured by Sekisui Chemical Co., Ltd.) Solvent 90 parts (toluene/methyl ethyl ketone = 1/1) (B) Magenta component Formula 3 dye 1 part Formula 4 dye 1 part Formula 5 dye 1 part Polyvinyl acetoacetal resin 4.5 parts (KS-5 manufactured by Sekisui Chemical Co., Ltd.) Solvent 90 parts (toluene / methyl ethyl ketone = 1/1) (C) Cyan component Dye of Formula 6 3 parts Polyvinylacetoacetal resin 4.5 parts (KS-5 manufactured by Sekisui Chemical Co., Ltd.) Solvent 90 parts (Toluene/methyl ethyl ketone = 1/1) Thermal transfer sheet A thermal transfer sheet C was obtained in the same manner as the thermal transfer sheet B except that the C yellow component was changed as follows. Coating liquid for forming a dye-carrying layer (A) Yellow component 1.5 parts of the dye of formula 1 1.5 parts of the dye of formula 2

<Substrate> A commercially available ceramic mug was immersed in the liquid of the following resin composition and transferred at 150°C.
Heat curing was performed for 0 minutes to form an epoxy resin layer having a thickness of 10 μm on the outer surface. Bisphenol A type epoxy resin 100 parts (Epikote YD8125 manufactured by Tohto Kasei Co., Ltd.) Polyamide curing agent 25 parts (Goodmide G700 manufactured by Tohto Kasei Co., Ltd.)

<Image formation on a mug> Using the thermal transfer sheet and the thermal transfer image-receiving sheet obtained in the above example, a video printer (VY-20 manufactured by Hitachi, Ltd.) was used.
0) transferred the dye image onto the receiving sheet. Here, a 16-step gray scale was used as the original image for transfer. Next, the thermal transfer image-receiving sheet having the dye image transferred thereon was brought into pressure contact with the above mug, and heated and pressed at 200° C. for 3 minutes to retransfer the dye image. Table 2 below shows combinations of thermal transfer sheets and thermal transfer image-receiving sheets used in the image forming test.

[Table 2]

<Evaluation of Transferred Image> Table 3 shows the results of visual evaluation of the density of the dye image retransferred onto the mug cup of the transferred material as described above.

[Table 3]

[0052]

As described above, when the thermal transfer image-receiving sheet of the present invention is used in the image forming method of the present invention, the density of the dye image obtained on the transferred material is improved due to the action of the dye-releasing layer. , image blurring, and fusion-bonding of the thermal transfer image-receiving sheet to the transfer-receiving body. Further, according to the image forming method of the present invention, it is not necessary to peel off only the dye receiving layer from the thermal transfer image receiving sheet and attach it to the transfer receiving material.

[Brief description of the drawing]

FIG. 1 is a first process diagram of an image forming method of the present invention; (Diagram showing the process during transfer from the thermal transfer sheet to the thermal transfer image receiving sheet)

FIG. 2 is a diagram showing the result of the first step of the image forming method of the present invention; (Diagram showing a thermal transfer image-receiving sheet to which a dye image has been transferred)

FIG. 3 is a second process diagram of the image forming method of the present invention; (The figure immediately before thermally transferring the dye image-transferred thermal transfer image-receiving sheet to the transfer material)

FIG. 4 is a diagram showing the result of the second step of the image forming method of the present invention; (Diagram showing the transferred material to which the dye image has been transferred and the used thermal transfer image-receiving sheet)

FIG. 5 is a vertical cross-sectional view of an example of the thermal transfer image-receiving sheet of the present invention;

FIG. 6 is a vertical cross-sectional view of another example of the thermal transfer image-receiving sheet of the present invention;

7 is a longitudinal sectional view of an example of a thermal transfer sheet that can be used in the image forming method of the invention; FIG.

FIG. 8 is a longitudinal sectional view of another example of a thermal transfer sheet that can be used in the image forming method of the invention;

[Description of symbols]

1 Thermal transfer sheet 2 Thermal transfer image receiving sheet 2a Thermal transfer image-receiving sheet with transferred dye image 2b Thermal transfer receiving sheet after retransfer of dye image 3 Dye image 4 Mug (transferred object) 4a Mug with dye image transferred (transferee) 11 support 12 Dye-carrying layer 13 Lubricant layer 21 base sheet 22 dye receiving layer 23 dye release layer 24 back layer

Claims (4)

[Claims] 1. A thermal transfer image-receiving sheet having at least a dye-receiving layer provided on a base sheet, characterized in that a dye-releasing layer containing a hydrophilic substance is provided between the base sheet and the dye-receiving layer. Thermal transfer image receiving sheet. 2. The thermal transfer image-receiving sheet according to claim 1, wherein the water-soluble substance is polyvinylpyrrolidone resin or alkyl vinyl ether/maleic anhydride copolymer resin. 3. The thermal transfer image-receiving sheet according to claim 1, further comprising a back layer mainly composed of a resin having a glass transition temperature of 160° C. or higher on the non-dye-releasing layer side of the base sheet. 4. forming a dye image on the dye-receiving layer of the thermal transfer image-receiving sheet according to any one of claims 1 to 3; An image forming method comprising the steps of transferring the dye image to a transfer receiving material by heating, and then peeling off the thermal transfer image receiving sheet from the transfer receiving material.