JP2011201180A - Thermal transfer sheet and image forming method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal transfer sheet and an image forming method using the thermal transfer sheet excelling in printing quality and blocking resistance in winding the thermal transfer sheet under high temperature preservation, having a function with high adhesiveness to a transfer object, and comprising a heat-fusible colored layer on a base material sheet.SOLUTION: The thermal transfer sheet 1 includes the heat-fusible colored layer 4 transferrable with heat, at least in part of one surface of the base material sheet 2 through a mold release layer 3. The heat-fusible colored layer 4 contains at least acrylic resin, polyester resin and a coloring agent. The acrylic resin has a KOH value of 2 (mgKOH/g) or more, and the polyester resin has an acid value less than 2 (mgKOH/g).

Description

  The present invention provides a heat-meltable colored layer on a base sheet having excellent printing quality, excellent anti-blocking property for winding a thermal transfer sheet under high-temperature storage, and high adhesion to a transfer target. The present invention relates to a provided thermal transfer sheet and an image forming method using the thermal transfer sheet.

  Conventionally, a thermal transfer method has been widely used as a simple printing method. In this thermal transfer method, a thermal transfer sheet provided with a color material layer on one side of a base sheet is superposed on a thermal transfer image-receiving sheet provided with an image receiving layer as necessary, and the thermal transfer is performed by a heating means such as a thermal head. In this method, an image is formed on a thermal transfer image receiving sheet by heating the back surface of the sheet into an image and selectively transferring the color material contained in the color material layer. The thermal transfer method is divided into a melt transfer method and a sublimation transfer method. The melt transfer system uses a thermal transfer sheet in which a heat-fusible colored layer in which a color material such as a pigment is dispersed in a binder such as a hot-melt wax or resin is supported on a base sheet such as a PET film, In this image forming method, energy corresponding to image information is applied to a heating means, and a color material is transferred together with a binder onto a thermal transfer image receiving sheet such as paper or a plastic sheet. An image obtained by the melt transfer method has a high density and excellent sharpness and is suitable for recording binary images such as characters.

  On the other hand, the sublimation transfer method uses a thermal transfer sheet in which a dye layer in which a dye that transfers heat by sublimation is dissolved or dispersed in a resin binder is supported on a base sheet such as a PET film, and is used as a heating means such as a thermal head. In this image forming method, energy is applied in accordance with image information, and only the dye is transferred onto a thermal transfer image receiving sheet in which a dye receiving layer is provided on a base sheet such as paper or plastic as necessary. In the sublimation transfer method, the amount of dye transfer can be controlled in accordance with the amount of energy applied, so that it is possible to form a gradation image in which the image density is controlled for each dot of the thermal head. Further, since the color material to be used is a dye, the formed image is transparent, and the reproducibility of intermediate colors when dyes of different colors are superimposed is excellent. Therefore, when using a thermal transfer sheet with dye layers of different hues such as yellow, magenta, cyan, and black, and transferring each color dye on the thermal transfer image-receiving sheet, the high-quality photo has excellent reproducibility of intermediate colors. A toned full-color image can be formed.

  The specific application of such a thermal transfer system is diverse. Typical examples include printing proofs, image output, CAD / CAM design and design output, various medical analytical instruments such as CT scans and endoscopic cameras, measuring instrument output applications and instant As an alternative to photos, output of ID cards, ID cards, credit cards, other face photos on cards, etc., as well as composite photos and amusement photos at amusement facilities such as amusement parks, game centers, museums, and aquariums Etc. With the diversification of applications as described above, there is an increasing demand for forming a thermal transfer image on an arbitrary object, and as one of the countermeasures, an intermediate transfer recording medium in which a receiving layer is detachably provided on a substrate is used. Using a thermal transfer sheet having a dye layer or a heat-meltable ink layer as the receiving layer, a colorant such as a dye or pigment is transferred to form an image, and then the intermediate transfer recording medium is heated to form a receiving layer. There has been proposed a method of transferring the image onto the transfer medium. (See Patent Document 1)

  In addition, the use of the above intermediate transfer recording medium can transfer the receiving layer to the transfer target, so that the color material is difficult to move and a high-quality image cannot be directly formed. It is preferably used for an object to be transferred which is easily fused with the material layer. For this reason, the intermediate transfer recording medium is preferably used for creating an identification card such as a passport or a printed matter such as a credit card / ID card. In addition, when transferring the image receiving layer to the transfer target, the image receiving layer formed by thermally transferring the coloring material such as sublimation dye or hot melt ink in the portion to be transferred is surely transferred onto the transfer target. In addition, after forming the image by transferring the color material from the thermal transfer sheet to the image receiving layer surface of the intermediate transfer recording medium provided with the image receiving layer on one side of the base sheet so as to be peelable, the above image There is known an image forming method in which an image receiving layer on which is formed is transferred to a transfer medium via an adhesive layer. (See Patent Document 2)

  In an image forming method in which a sublimation dye or hot melt ink is thermally transferred to a transfer medium using an intermediate transfer recording medium as described above, and the receiving layer on which an image is formed is transferred, the sublimation dye or hot melt ink is transferred to the receiving layer. Is transferred directly to form an image, and a release agent is added to the receiving layer so that the image is formed without fusing the receiving layer and the dye layer. However, when the hot-melt ink is transferred to the receiving layer, transferability of the hot-melt ink to the receiving layer is inferior, and there is a problem that the printing portion is liable to be blurred or blurred and the printing quality is not good. In addition, the adhesion between the receiving layer of the intermediate transfer recording medium and the hot-melt ink is not sufficient, and when the receiving layer formed with an image is transferred to a transfer member such as a card, the transfer member and the receiving layer There is a problem of insufficient adhesion.

  As a thermal transfer sheet having a heat-meltable ink layer on a substrate, for example, in Patent Document 3, a resin is mainly used as a binder for a heat-meltable ink layer, and a thermoplastic resin having a softening point of 50 to 80 ° C. is an acrylic resin. And the use of a mixture of polyester resin. However, even if it is possible to increase the transfer sensitivity of the heat-meltable ink layer by using the above-mentioned softening point, winding of the heat transfer sheet under high-temperature storage etc. causes blockage in the overlapping part of the heat transfer sheet. There is an easy problem.

  In addition, in order to eliminate printing blurring and slippage in the thermal transfer sheet of the hot melt transfer method, a hot melt ink layer is provided on the base material sheet via a release layer. Although transferability is controlled, there is a problem that the performance of the release layer tends to vary. For example, in a release layer containing a silicone-based resin, it is difficult to form a uniform coating film, the thickness of the film varies, and when the release layer is formed with an aqueous coating solution, The release performance varies due to a slight change in temperature in drying the release layer after coating.

A heat-meltable ink layer is transferred from a thermal transfer sheet to a receptive layer having a releasability of an intermediate transfer recording medium, and the receptive layer to which the heat-meltable ink layer is transferred is transferred to a transfer medium for use. In particular, the performance of the above hot-melt ink layer is required. In other words, printing can be transferred to the receiving layer of the intermediate transfer recording medium without blurring or blurring, and blocking in winding of the thermal transfer sheet under high temperature storage can be prevented, and adhesion with the receiving layer of the printed part can be prevented. And sufficient adhesion between the transferred receiving layer and the transfer target. However, there is a problem that there is nothing that sufficiently satisfies the performance of the above hot-melt ink layer.
JP-A-62-238791 Japanese Unexamined Patent Publication No. 7-52522 JP-A-9-272265

  Therefore, the present invention solves the problems as described above, has excellent printing quality, excellent anti-blocking property for winding the thermal transfer sheet under high temperature storage, and has a function of high adhesion to the transfer target. Another object of the present invention is to provide a thermal transfer sheet in which a heat-meltable colored layer is provided on a base sheet and an image forming method using the thermal transfer sheet.

  In view of the above situation, earnest research and development has been progressed, and the present invention can be transferred by heat through at least a part of one surface of the base sheet through a release layer. In the thermal transfer sheet provided with a heat-meltable colored layer, the heat-meltable colored layer contains at least an acrylic resin, a polyester resin, and a colorant, and the acrylic resin has a KOH value of 2 (mgKOH / g) or more. The polyester resin has an acid value of less than 2 (mgKOH / g).

  According to a second aspect of the present invention, the KOH value of the acrylic resin contained in the heat-meltable colored layer according to the first aspect is 15 (mgKOH / g) or more. According to a third aspect of the present invention, the acrylic resin contained in the hot-melt colored layer according to the first or second aspect is an amine-modified acrylic resin.

As Claim 4 of this invention, the acrylic resin and polyester resin which are contained in the hot-melt colored layer as described in any one of Claims 1-3 are mixed by the mass ratio of 85: 15-60: 40. It is characterized by. In addition, as a fifth aspect of the present invention, the heat-meltable colored layer according to any one of the first to fourth aspects has a coating amount of 0.6 to 1.2 g / m ² in a dry state. Features.

  The image forming method according to claim 6 of the present invention uses the thermal transfer sheet according to any one of the above, and the intermediate transfer recording medium having a releasable receiving layer on one surface of the base sheet. An image is formed by transferring the image-forming receiving layer of the intermediate transfer recording medium to a transfer medium after transferring the heat-meltable colored layer to the receiving layer and forming an image.

  According to the present invention, due to the thermal transfer sheet having the above-described configuration, the transferred print portion is less likely to be blurred or slipped, has excellent print quality, and can be prevented from being blocked by winding the thermal transfer sheet under high temperature storage. Further, the adhesiveness between the printing portion and the receiving layer is high, and further, the adhesiveness between the transfer target and the printing portion is high. In addition, using the above-described thermal transfer sheet, after an image is formed by transferring a heat-meltable colored layer to the receiving layer on an intermediate transfer recording medium having a receiving layer having releasability on one side of the base sheet. The image-formed receiving layer of the intermediate transfer recording medium can be transferred to a transfer medium to form an image. At that time, the adhesiveness between the receiving layer of the intermediate transfer recording medium and the transferred heat-meltable colored layer is high, and the adhesiveness between the receiving layer on which an image has been formed and the transfer target is also high.

It is the schematic which shows one embodiment of the thermal transfer sheet of this invention. It is the schematic explaining the image forming method of this invention.

Next, an embodiment of the invention will be described in detail.
FIG. 1 is a schematic view showing one embodiment of a thermal transfer sheet 1 of the present invention, in which a release layer 3 and a heat-meltable colored layer 4 are provided on a base sheet 2 and the other side of the base sheet 2 is provided. The back layer 5 is provided on this surface. Not only the illustrated one but also an antistatic layer may be provided on one or both of the front and back surfaces of the thermal transfer sheet, or other layers may be added as appropriate. Below, each layer which comprises the thermal transfer sheet of this invention is demonstrated in detail.

(Substrate sheet)
As the base material sheet 2 used in the thermal transfer sheet of the present invention, the same base material sheet as that used in the conventional thermal transfer sheet can be used as it is, and other materials can be used. Not. Specific examples of preferred substrates include, for example, polyester, polypropylene, cellophane, polycarbonate, cellulose acetate, polyethylene, polyvinyl chloride, polystyrene, nylon, polyimide, polyvinylidene chloride, polyvinyl alcohol, fluororesin, chlorinated rubber, ionomer and the like. There are papers such as plastic film, condenser paper, paraffin paper, etc., and any of these may be combined. The thickness of the base sheet can be appropriately changed depending on the material so that its strength and thermal conductivity are appropriate, but is preferably about 2 to 12 μm in view of printing (recording) sensitivity. That is, if the thickness is less than 2 μm, the strength as a substrate sheet tends to be insufficient, and if the thickness exceeds 12 μm, heat at the time of printing (recording) becomes difficult to be transmitted to the transfer layer.

(Release layer)
On the base material sheet, a release layer 3 for facilitating peeling of the hot-melt coloring layer from the base material sheet is provided. As the resin constituting the release layer, thermoplastic resins such as polymethyl methacrylate, polyethyl methacrylate, polybutyl acrylate and other acrylic resins, polyvinyl acetate, vinyl chloride vinyl acetate copolymer, polyvinyl alcohol, Vinyl resins such as polyvinyl butyral, cellulose derivatives such as ethyl cellulose, nitrocellulose, and cellulose acetate, or unsaturated polyester resins that are thermosetting resins, polyester resins, polyurethane resins, aminoalkyd resins, epoxy groups, amino groups, etc. A silicone-modified resin having a reactive group can be used. If necessary, wax, silicone wax, silicone resin, melamine resin, fluorine resin, talc, silica fine powder, lubricant such as surfactant and metal soap, etc. Added.

  In the thermal transfer sheet of the present invention, the binder resin constituting the heat-meltable colored layer mainly comprises an acrylic resin and a polyester resin. However, in the case of an acrylic resin having a reactive group such as an amine-modified acrylic resin, the binder resin has a release layer. It reacts with a silicone-modified resin having an epoxy group, that is, the amino group of the acrylic resin and the epoxy group of the silicone-modified resin react and bond to each other, and the release force on the thermal transfer sheet (release layer and hot-melt colored layer) It is preferable because the adhesive strength can be stabilized.

  When the silicone-modified resin having an epoxy group is used in a release layer, a curing catalyst is used to cure the silicone-modified resin. Examples of the silicone-modified resin having an epoxy group include a silicone-modified acrylic resin and a silicone-modified urethane resin. By curing this silicone-modified resin having an epoxy group, when the heat transfer sheet is heated, the silicone component of the release layer is not transferred to the heat-fusible colored layer so that the heat-fusible colored layer is transferred during printing. Increases sex.

  The curing catalyst for curing the silicone-modified resin having an epoxy group is not particularly limited, but examples thereof include aluminum compounds such as aluminum alkoxide and aluminum chelate, N-β-aminoethyl-γ-aminopropyltrimethoxy, and the like. Examples thereof include amine-based silane coupling agents such as silane and N-β-aminoethyl-γ-aminopropylmethyldimethoxysilane.

The release layer is prepared by dissolving or dispersing the components described above in a solvent to prepare a coating solution, and applying and drying the coating solution to form a release layer. The coating amount of the release layer is about 0.1 to 5.0 g / m ² when dried.

(Hot-melting colored layer)
The binder used for the heat-meltable colored layer is mainly composed of a resin and is composed of at least an acrylic resin and a polyester resin. The acrylic resin has a KOH value of 2 (mgKOH / g) or more, and the polyester resin has an acid value of less than 2 (mgKOH / g). In the acrylic resin, the KOH value is specified by the KOH value, but the KOH value specified by the present invention is the acid value which is the number of mg of potassium hydroxide required to neutralize 1 g of resin solids, and the resin solids. It means both the hydrochloric acid required to neutralize 1 g of a minute and the amine value which is the number of mg of potassium hydroxide equivalent. However, the acid value and amine value are determined by potentiometric titration according to JIS K 0070.

  An acrylic resin having a KOH value of 2 (mgKOH / g) or more and a polyester resin having an acid value of less than 2 (mgKOH / g) are not compatible with each other, that is, are incompatible resins. It is phase-separated and takes a sea-island structure. By adopting this sea-island structure, the heat-meltable colored layer forms fine irregularities at the interface with the release layer, provides appropriate transferability during printing, and prevents print blur and blurring print quality. It will be excellent. In addition, since the heat-fusible colored layer has a sea-island structure, the surface of the heat-fusible colored layer has a fine uneven shape, and blocking can be prevented even when the winding of the heat transfer sheet is stored at high temperature. It was. The “scratch” in the present invention refers to a printing defect in which the heat-meltable colored layer cannot be transferred to all or part of the region to which the heat-meltable colored layer should be transferred. The “slip” refers to a printing defect that is transferred from the heat-meltable colored layer to all or a part of the region that should not be transferred by the heat-meltable colored layer.

  Examples of the acrylic resin having a KOH value of 2 (mgKOH / g) or more include, for example, polyacrylic acid, polymethacrylic acid, polyacrylic acid alkyl ester, polymethacrylic acid, and a thermoplastic resin comprising these copolymers. Can be preferably used. In the case of this acrylic resin, the acid value is 2 (mgKOH / g) or more, and the upper limit is 25 (mgKOH / g). As the acrylic resin used in the heat-meltable colored layer of the present invention, those having an acid value of 15 (mgKOH / g) or more and 22 (mgKOH / g) are anti-blocking for winding a thermal transfer sheet under high temperature storage. Excellent in properties and preferable. When the acid value of the acrylic resin is less than 2 (mg KOH / g), the compatibility with the polyester resin to be mixed becomes high, and the sea-island structure cannot be formed. On the other hand, when the acid value of the acrylic resin is too high, there are too many acidic functional groups, the storage stability in the coating solution is lowered, and it becomes impossible to form a heat-sealed colored layer having a stable sea-island structure.

  By using an amine-modified acrylic resin as the acrylic resin of the heat-meltable colored layer, the amino group of the acrylic resin and the epoxy group of the silicone-modified resin in the release layer react and bond to each other in the thermal transfer sheet. The peeling force (adhesive strength between the release layer and the heat-meltable colored layer) can be stabilized, which is preferable. Since the epoxy group remains even after the silicone-modified resin having an epoxy group contained in the release layer is cured, an acrylic resin having an amino group in its side chain, which is a functional group highly reactive with the epoxy group Is preferably used.

  In the case of the amine-modified acrylic resin, the KOH value is an amine value, and the amine value is 2 (mgKOH / g) or more. The upper limit of the amine value is 25 (mgKOH / g). The amine-modified acrylic resin used in the heat-meltable colored layer of the present invention has a KOH value of 15 (mgKOH / g) or more and 22 (mgKOH / g) or less. It is excellent in blocking resistance and is preferable. When the amine value of the amine-modified acrylic resin is less than 2 (mgKOH / g), the compatibility with the polyester resin to be mixed becomes high, and the sea-island structure cannot be formed. On the other hand, if the acid value of the amine acrylic resin is too high, there are too many amino groups, the storage stability in the coating solution is lowered, and it becomes impossible to form a heat-sealed colored layer having a stable sea-island structure.

  By containing the amine-modified acrylic resin and the polyester resin having an acid value of less than 2 (mgKOH / g) in the heat-melting colored layer, the heat-melting colored layer is handled during handling other than the heat printing of the thermal transfer sheet. Is not peeled off from the substrate sheet, and there is no “scratch” in thermal transfer printing, and a sharp print can be obtained.

  As the acrylic resin of the heat-meltable colored layer, a resin having a weight average molecular weight (Mw) of 30000 to 70000, preferably 45000 to 65000 is used even in the case of an amine-modified acrylic resin. The molecular weight is represented by a value measured by the GPC method. If the weight average molecular weight of the acrylic resin is lower than the above range, printing blur tends to occur, and if it is higher than the above range, printing blur tends to occur. In addition, as the acrylic resin of the heat-meltable colored layer, those having a glass transition point of 50 ° C. to 90 ° C. are used.

  As the polyester resin of the heat-meltable colored layer, one having an acid value of less than 2 (mgKOH / g) is used. The polyester resin is an esterified product of a polybasic acid component and a polyhydric alcohol component. Examples of the polybasic acid component include phthalic anhydride, isophthalic acid, terephthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, succinic acid, fumaric acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, maleic anhydride , One or more dibasic acids selected from itaconic acid and the like and lower alkyl esterified products of these acids are mainly used, and monobasic acids such as benzoic acid, crotonic acid, and pt-butylbenzoic acid as necessary , Tribasic or higher polybasic acids such as trimellitic anhydride, methylcyclohexeric tricarboxylic acid and pyromellitic anhydride are used in combination.

  Examples of the polyhydric alcohol component include ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 3-methylpentanediol, 1,4-hexanediol, 1,6-hexanediol, and cyclohexanedimethanol. Dihydric alcohols such as hydrogenated bisphenol A, ethylene oxide adducts of bisphenol A, propylene oxide adducts of bisphenol A, etc. These trihydric or higher polyhydric alcohols can be used in combination. These polyhydric alcohols can be used alone or in admixture of two or more. The esterification or transesterification reaction of both components can be performed by a method known per se, for example, obtained by polycondensation of the polybasic acid component and the polyhydric alcohol component at a temperature of about 180 to 250 ° C. be able to.

  When the polyester resin has an acid value of less than 2 (mgKOH / g), when mixed with the above acrylic resin, they are not compatible with each other, that is, become incompatible resins, and microphase separation occurs. Necessary to take the structure. It can be considered that the difference in acid value (KOH value) between the acrylic resin and the polyester resin can be increased to increase the difference between the polarities of the two, resulting in incompatible resins. When the acid value of the polyester resin is 2 (mgKOH / g) or more, the compatibility with the acrylic resin to be mixed becomes high, and the sea-island structure cannot be formed. As a polyester resin of a heat-meltable colored layer, a weight average molecular weight (Mw) of 5000 to 10000, preferably 5000 to 8000 is used. If the weight average molecular weight of the polyester resin is lower than the above range, printing blur tends to occur, and if it is higher than the above range, printing blur tends to occur. In addition, as the polyester resin of the heat-meltable colored layer, those having a glass transition point of 50 ° C. to 90 ° C. are used.

  The acrylic resin and the polyester resin contained in the heat-meltable colored layer are preferably mixed at a mass ratio of 85:15 to 60:40, and mixed at a mass ratio of 85:15 to 70:30. It is more preferable. When the content ratio of the polyester resin is reduced at this mixing ratio, printing blur tends to occur. On the other hand, when the polyester resin content ratio is too high, printing slipping easily occurs. In the heat-meltable colored layer in the thermal transfer sheet of the present invention, an acrylic resin having a different chemical structure and a KOH value of 2 (mgKOH / g) or more and a polyester resin having an acid value of less than 2 (mgKOH / g) They are incompatible, and these polymers can form a stable microphase separation state, so that the properties of the sea and island polymers can be expressed without being offset. That is, from the above mixing ratio, the acrylic resin and polyester resin contained in the hot-melt colored layer. The acrylic resin has a higher ratio and becomes a sea region, and the polyester resin forms a dispersed island region with respect to the sea region.

  As described above, the acrylic resin contained in the heat-meltable colored layer has a weight average molecular weight (Mw) in the range of about 30,000 to 70,000, has a high molecular weight, and has a sea-island structure. In addition, the film strength of the heat-meltable colored layer is mainly increased, and the adhesiveness of the heat-meltable colored layer to the intermediate transfer recording medium can be increased. The polyester resin contained in the heat-meltable colored layer has a weight average molecular weight (Mw) in the range of about 5,000 to 10,000, is a low molecular weight resin, is an island region of a sea-island structure, and has a transfer sensitivity in printing. It can be increased, and printing blurring can be prevented.

  The resin that constitutes the heat-meltable colored layer has various performances that cannot be met with a single polymer. By mixing a specific acrylic resin and a specific polyester resin, both take a sea-island structure. The characteristics of the resin can be demonstrated individually. As a result, there is little blurring or slippage in the transferred printed part, that is, excellent print quality, excellent blocking resistance of winding of the thermal transfer sheet under high temperature storage, and high adhesion to the transfer target A thermal transfer sheet having

  As the colorant contained in the heat-meltable colored layer, each colorant such as yellow, magenta, cyan, black, and white can be appropriately selected from conventionally known dyes and pigments. In the image forming method using the thermal transfer sheet in the present invention, it is preferable to use a black pigment typified by carbon black for the heat-meltable colored layer in heat-melt transfer suitable for recording binary images such as characters.

  In the heat-meltable colored layer of the present invention, it is preferable to use an ink composition mixed in a proportion of 30 to 60% by weight of a colorant and 40 to 70% by weight of a binder resin. If the colorant is less than the above range, the coating amount must be increased in order to obtain the density, resulting in insufficient printing sensitivity. On the other hand, when the amount of the colorant is larger than the above range, the film formability cannot be obtained, which causes a reduction in scratching property after printing. By including the colorant in the above range, high-density and sharp printing can be performed.

The heat-meltable colored layer is formed by coating the colorant component and the binder resin component as described above, and, if necessary, a solvent component such as water or an organic solvent as necessary. The coating amount is 0.6 to 1.2 g / m in a dry state by a conventionally known method such as hot melt coating, hot lacquer coating, gravure direct coating, gravure reverse coating, knife coating, air coating, roll coating, etc. ² is preferable, and 0.8 to 1.0 g / m ² is more preferable. When the coating amount of the dried coating film is less than 0.6 g / m ² , a uniform colored layer cannot be obtained due to film formation problems, and printing blur tends to occur. On the other hand, when the coating amount exceeds 1.2 g / m ² , high energy is required at the time of printing transfer, and printing can be performed only by a special thermal transfer printer, and the printing is liable to occur.

(Back layer)
In the thermal transfer sheet of the present invention, if necessary, adverse effects such as sticking or wrinkles due to heat from a thermal head or the like as a thermal transfer unit on the back surface of the base sheet, that is, the surface opposite to the surface where the heat-meltable colored layer is provided. In order to prevent this, the back layer 5 can be provided. The resin for forming the back layer may be any conventionally known resin such as polyvinyl butyral resin, polyvinyl acetoacetal resin, polyester resin, vinyl chloride-vinyl acetate copolymer, polyether resin, polybutadiene resin, styrene- Butadiene copolymer, acrylic polyol, polyurethane acrylate, polyester acrylate, polyether acrylate, epoxy acrylate, urethane or epoxy prepolymer, nitrocellulose resin, cellulose nitrate resin, cellulose acetopropionate resin, cellulose acetate butyrate resin, Cellulose acetate hydrodiene phthalate resin, cellulose acetate resin, polyamide resin, polyimide resin, polyamideimide resin, polycarbonate resin, salt Polyolefin resins, and chlorinated polyolefin resins.

Examples of the slipperiness-imparting agent added to or overcoated on the back layer made of these resins include phosphate ester, silicone oil, graphite powder, silicone-based graft polymer, fluorine-based graft polymer, acrylic silicone graft polymer, acrylic siloxane, aryl siloxane, etc. The silicone polymer is preferably a layer comprising a polyol, for example, a polyalcohol polymer compound, a polyisocyanate compound and a phosphate ester compound, and it is more preferable to add a filler. The back layer is prepared by dissolving or dispersing the above-described resin, slipperiness-imparting agent, and filler with an appropriate solvent to prepare a back layer forming ink. Further, for example, it can be formed by applying and drying by a forming means such as a gravure printing method, a screen printing method, a reverse coating method using a gravure plate. The coating amount of the back layer is sufficient as long as it can achieve prevention of fusion, lubricity, and the like, and is usually about 0.1 to 3 g / m ² at the time of drying.

(Image forming method)
The image forming method of the present invention uses the thermal transfer sheet according to any one of the above, the intermediate transfer recording medium provided with a releasable receiving layer on one side of the base sheet, the receiving layer After the heat-meltable colored layer is transferred to form an image, the image-formed receiving layer of the intermediate transfer recording medium is transferred to a transfer target to form an image. FIG. 2 is a schematic diagram illustrating the image forming method of the present invention.
(1) An intermediate transfer recording medium 10 having a receiving layer 13 via a release layer 12 is prepared on one side of a base sheet 11, and the intermediate transfer recording medium 10 is a back layer on the other side of the base sheet 11. 14 is provided, and the heat-meltable colored layer is transferred to the receiving layer 13 by using a thermal transfer sheet as shown in FIG. Although not shown, the sublimation transfer image 7 is formed on the receiving layer 13 by a dye layer provided on a base sheet of a separately prepared thermal transfer sheet. Since the receiving layer 13 is formed with the release layer 12, it is easy to release from the base material sheet 11 at the time of thermal transfer, and the back surface layer 14 is provided on the other surface of the base material sheet 11. Prevents adverse effects such as sticking and wrinkles due to heat from the head and heat roll.

(2) Next, the receiving layer 13 and the release layer 12 on which the image 6 and the sublimation transfer image 7 are formed are transferred from the intermediate transfer recording medium 10 to the transfer target 8, and the transfer target 8 having the image formed thereon. That is, an image formed product 9 is obtained.

Below, each element which comprises the intermediate transfer recording medium applied with said image forming method is demonstrated.
(Substrate sheet)
As the base material sheet 11 constituting the intermediate transfer recording medium, the same base material sheet as that used in the conventional intermediate transfer recording medium can be used as it is, and is not particularly limited. Specifically, the same material and thickness as the base material sheet described in the thermal transfer sheet can be used.

(Peeling layer)
In the intermediate transfer recording medium, a receiving layer can be formed on the base sheet via the release layer 12. By having this release layer, the receiving layer can be reliably and easily transferred from the intermediate transfer recording medium to the transfer medium.

The release layer can be formed from, for example, a binder resin and a release material. Examples of the binder resin include thermoplastic resins such as polymethyl methacrylate, polyethyl methacrylate, and polybutyl acrylate, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, polyvinyl alcohol, polyvinyl butyral, and the like. Vinyl-based resins, cellulose derivatives such as ethyl cellulose, nitrocellulose, and cellulose acetate, unsaturated polyester resins that are thermosetting resins, polyester resins, polyurethane resins, amino alkyd resins, and the like can be used. As the releasable material, waxes, silicone waxes, silicone resins, melamine resins, fluorine resins, fine powders of talc and silica, lubricants such as surfactants and metal soaps, and the like can be used. The release layer was prepared by dissolving or dispersing the above-mentioned necessary materials with an appropriate solvent to prepare a release layer coating solution, and using a gravure printing method, screen printing method or gravure plate on the base sheet. It can be formed by applying and drying by means such as reverse coating. The coating amount is about 0.05 to 1 g / m ² when dried.

(Receptive layer)
The receiving layer 13 is provided so as to be positioned on the surface of the intermediate transfer recording medium. On the receiving layer, an image is formed by thermal transfer from the thermal transfer sheet of the present invention by thermal transfer. In addition, a sublimation transfer image can be formed on the receiving layer by a thermal transfer method from a thermal transfer sheet having a dye layer. Then, the receiving layer of the intermediate transfer recording medium on which the image is formed is transferred to the transfer target, and as a result, a printed matter is formed. As a material for forming the receiving layer, a conventionally known resin material that can easily receive the heat transferable coloring material of the sublimation dye can be used. For example, polyolefin resin such as polypropylene, halogenated resin such as polyvinyl chloride or polyvinylidene chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, ethylene-vinyl acetate copolymer or polyacrylate Vinyl resins, polyester resins such as polyethylene terephthalate or polybutylene terephthalate, polystyrene resins, polyamide resins, copolymers of olefins such as ethylene or propylene and other vinyl polymers, cellulose resins such as ionomers or cellulose diastases Polycarbonate, etc., and vinyl chloride resin, acrylic-styrene resin or polyester resin is particularly preferable.

The receiving layer preferably contains a release agent in the above resin in order to prevent thermal fusion with the dye layer of the thermal transfer sheet. As the mold release agent, silicone oil, phosphate ester surfactants, fluorine compounds and the like can be used, and among these, silicone oil is particularly preferably used. The amount of the release agent added is preferably 0.2 to 30 parts by mass with respect to 100 parts by mass of the binder resin that forms the receiving layer. The receptive layer is a gravure printing method, screen printing, or the like obtained by adding a necessary additive such as a release agent to the above resin on the base sheet, and dissolving or dispersing it in a solvent such as water or an organic solvent. It can be formed by applying a usual method such as a reverse roll coating method using a gravure plate or a gravure plate. The coating amount is about 0.1 to 10 g / m ² after coating and drying.

(Transfer material)
The transferred object onto which the image-formed receiving layer is transferred can be composed of the following substrate. For example, natural pulp paper, coated paper, tracing paper, plastic film that is not deformed by heat during transfer, glass, metal, ceramics, wood, cloth, etc. may be used. Natural pulp paper is not particularly limited, for example, fine paper, art paper, lightweight coated paper, fine coated paper, coated paper, cast coated paper, synthetic resin or emulsion impregnated paper, synthetic rubber latex impregnated paper, synthetic resin internal additive Examples thereof include paper and thermal transfer paper. Regarding the shape and application of the transferred object, stock certificates, securities, certificates, passbooks, boarding tickets, car horse tickets, stamps, stamps, appreciation tickets, admission tickets, tickets, etc., cash cards, credit cards, prepaid cards, Cards such as members cards, greeting cards, postcards, business cards, driver's licenses, IC cards, optical cards, cases such as cartons, containers, bags, forms, envelopes, tags, OHP sheets, slide films, bookmarks, Calendars, posters, brochures, menus, passports, POP supplies, coasters, displays, nameplates, keyboards, cosmetics, wristwatches, lighters and other accessories, stationery, report paper and other stationery, building materials, panels, emblems, keys, cloth, clothing , Footwear, radio, TV, calculator, OA equipment, etc., various samples , Album, In addition, computer graphics output, medical image output, etc., do not ask the kind.

Next, the present invention will be described more specifically with reference to examples. In the text, “part” or “%” is based on mass unless otherwise specified.
Example 1
When a base sheet is dried, a coating solution for the back layer having the following composition is applied to one side of a 4.5 μm thick biaxially stretched polyethylene terephthalate film (Lumirror, manufactured by Toray Industries, Inc.) by a wire bar coating method. The coating amount was 1.0 g / m ² and dried (100 ° C. for 60 seconds) to form a back layer. Next, on the surface opposite to the surface on which the back surface layer of the base material sheet is formed, a release layer coating liquid having the following composition is applied by gravure coating so that the coating amount when dried is 1.0 g / m ^2. And dried (80 ° C. for 60 seconds) to form a release layer, and on the release layer, a coating solution 1 for heat-meltable colored layer having the following composition is applied by gravure coating at the time of drying. The amount is 0.2 g / m ² , 0.4 g / m ² , 0.6 g / m ² , 0.8 g / m ² , 1.0 g / m ² , 1.2 g / m ² , 1.4 g / m ^2. , 1.6 g / m ² , each of which was applied and dried to form a heat-meltable colored layer, and the heat transfer sheet of Example 1 was applied in eight different amounts of the heat-meltable colored layer. It was made with.

(Coating solution composition for back layer)
Acrylic nitrile-styrene copolymer 11 parts Linear saturated polyester resin 0.3 part Zinc stearyl phosphate 6 parts Melamine resin powder 3 parts Toluene / ethanol = 50/50 (mass ratio) 80 parts

(Coating liquid composition for release layer)
Silicone modified acrylic resin (silicone modified acrylic resin having epoxy group, Cell Top 226, manufactured by Daicel Chemical Industries, Ltd.) 16 parts Aluminum catalyst (Cell Top CAT-A, manufactured by Daicel Chemical Industries, Ltd.) 3 parts Methyl ethyl ketone 8 parts Toluene 8 parts

(Coating liquid 1 for heat-meltable colored layer)
Colorant (carbon black dispersant, solid content 46%, blended carbon black 40%, dispersant 6%, toluene / ethyl acetate = 1/1) 23.9 parts amine-modified acrylic resin 21.6 parts (amine 20.5 (mg KOH / g), solid content 45%, glass transition point 90 ° C., weight average molecular weight 45000, manufactured by DIC)
4.18 parts of polyester resin (trade name Byron 220, acid value less than 2 (mgKOH / g), solid content 100%, glass transition point 53 ° C., weight average molecular weight 5000, manufactured by Toyobo Co., Ltd.)
Toluene / methyl ethyl ketone = 50/50 (mass ratio) 50.32 parts

(Example 2)
The heat transfer sheet of Example 2 was heated in the same manner as in Example 1 except that the heat-fusible colored layer coating solution 1 was changed to one having the following composition under the preparation conditions of the heat transfer sheet prepared in Example 1. It produced with eight types from which the application quantity of a meltable colored layer differs.
(Coating liquid 2 for heat-meltable colored layer)
Colorant (carbon black dispersant, solid content 46%, blended carbon black 40%, dispersant 6%, toluene / ethyl acetate = 1/1) 23.9 parts Amine-modified acrylic resin 18.5 parts (amine 10 (mgKOH / g), solid content 45%, glass transition point 60 ° C., weight average molecular weight 45000, manufactured by DIC)
5.56 parts of polyester resin (trade name Byron 220, acid value of less than 2 (mgKOH / g), solid content 100%, glass transition point 53 ° C., weight average molecular weight 5000, manufactured by Toyobo Co., Ltd.)
Toluene / methyl ethyl ketone = 50/50 (mass ratio) 52.04 parts

(Example 3)
The heat transfer sheet of Example 3 was heated in the same manner as in Example 1 except that the heat-fusible colored layer coating solution 1 was changed to one having the following composition under the preparation conditions of the heat transfer sheet prepared in Example 1. It produced with eight types from which the application quantity of a meltable colored layer differs.
(Coating liquid 3 for hot-melt coloring layer)
Colorant (carbon black dispersant, solid content 46%, blended carbon black 40%, dispersant 6%, toluene / ethyl acetate = 1/1) 27.2 parts amine-modified acrylic resin 20.8 parts (amine 10 (mgKOH / g), solid content 45%, glass transition point 60 ° C., weight average molecular weight 45000, manufactured by DIC)
3.13 parts of polyester resin (trade name Byron 885, acid value of less than 2 (mgKOH / g), solid content 100%, glass transition point 79 ° C., weight average molecular weight 8000, manufactured by Toyobo Co., Ltd.)
Toluene / methyl ethyl ketone = 50/50 (mass ratio) 48.87 parts

Example 4
The heat transfer sheet of Example 4 was heated in the same manner as in Example 1 except that the heat-fusible colored layer coating solution 1 was changed to one having the following composition under the preparation conditions of the heat transfer sheet prepared in Example 1. It produced with eight types from which the application quantity of a meltable colored layer differs.
(Coating liquid 4 for heat-meltable colored layer)
Colorant (carbon black dispersant, solid content 46%, blended carbon black 40%, dispersant 6%, toluene / ethyl acetate = 1/1) 21.7 parts acrylic resin 31.25 parts (trade name BR -64, acid value 2 (mgKOH / g), solid content 40%, glass transition point 55 ° C., weight average molecular weight 65000, manufactured by Mitsubishi Rayon Co., Ltd.)
2.5 parts of polyester resin (trade name Byron 885, acid value less than 2 (mgKOH / g), solid content 100%, glass transition point 79 ° C., weight average molecular weight 8000, manufactured by Toyobo Co., Ltd.)
Toluene / methyl ethyl ketone = 50/50 (mass ratio) 44.55 parts

(Example 5)
The thermal transfer sheet of Example 5 was heated in the same manner as in Example 1 except that the heat-fusible colored layer coating solution 1 was changed to one having the following composition under the production conditions of the thermal transfer sheet produced in Example 1. It produced with eight types from which the application quantity of a meltable colored layer differs.
(Coating liquid 5 for heat-meltable colored layer)
Colorant (carbon black dispersant, solid content 46%, blended carbon black 40%, dispersant 6%, toluene / ethyl acetate = 1/1) 21.7 parts acrylic resin 41.7 parts (trade name BR -77, acid value 18.5 (mgKOH / g), solid content 30%, glass transition point 80 ° C., weight average molecular weight 65000, manufactured by Mitsubishi Rayon Co., Ltd.)
2.5 parts of polyester resin (trade name Byron 885, acid value less than 2 (mgKOH / g), solid content 100%, glass transition point 79 ° C., weight average molecular weight 8000, manufactured by Toyobo Co., Ltd.)
Toluene / methyl ethyl ketone = 50/50 (mass ratio) 34.1 parts

(Comparative Example 1)
The heat transfer sheet of Comparative Example 1 was heated in the same manner as in Example 1 except that the heat-fusible colored layer coating solution 1 was changed to one having the following composition under the preparation conditions of the heat transfer sheet prepared in Example 1. It produced with eight types from which the application quantity of a meltable colored layer differs.
(Coating liquid 6 for heat-meltable colored layer)
Colorant (carbon black dispersant, solid content 46%, blended carbon black 40%, dispersant 6%, toluene / ethyl acetate = 1/1) 24.1 parts Vinyl chloride-vinyl acetate copolymer 46. 3 parts (Brand name Solvein CL, solid content 30%, glass transition point 75 ° C., weight average molecular weight 20000, manufactured by Nissin Chemical Industry Co., Ltd.)
Toluene / methyl ethyl ketone = 50/50 (mass ratio) 29.6 parts

(Comparative Example 2)
The heat transfer sheet of Comparative Example 2 was heated in the same manner as in Example 1 except that the heat-fusible colored layer coating solution 1 was changed to one having the following composition under the preparation conditions of the heat transfer sheet prepared in Example 1. It produced with eight types from which the application quantity of a meltable colored layer differs.
(Coating solution 7 for heat-meltable colored layer)
Colorant (carbon black dispersant, solid content 46%, blended carbon black 40%, dispersant 6%, toluene / ethyl acetate = 1/1) 24.1 parts Amine-modified acrylic resin 30.9 parts (amine 20.5 (mg KOH / g), solid content 45%, glass transition point 90 ° C., weight average molecular weight 45000, manufactured by DIC)
Toluene / methyl ethyl ketone = 50/50 (mass ratio) 45.0 parts

(Comparative Example 3)
The heat transfer sheet of Comparative Example 3 was heated in the same manner as in Example 1 except that the heat-fusible colored layer coating solution 1 was changed to one having the following composition under the production conditions of the heat transfer sheet produced in Example 1. It produced with eight types from which the application quantity of a meltable colored layer differs.
(Coating liquid 8 for heat-meltable colored layer)
Colorant (carbon black dispersant, solid content 46%, blended carbon black 40%, dispersant 6%, toluene / ethyl acetate = 1/1) 24.1 parts Amine-modified acrylic resin 30.9 parts (amine 10 (mgKOH / g), solid content 45%, glass transition point 60 ° C., weight average molecular weight 45000, manufactured by DIC)
Toluene / methyl ethyl ketone = 50/50 (mass ratio) 45.0 parts

(Comparative Example 4)
The heat transfer sheet of Comparative Example 4 was heated in the same manner as in Example 1 except that the heat-fusible colored layer coating solution 1 was changed to one having the following composition under the production conditions of the heat transfer sheet produced in Example 1. It produced with eight types from which the application quantity of a meltable colored layer differs.
(Coating liquid 9 for heat-meltable colored layer)
Colorant (carbon black dispersant, solid content 46%, blended carbon black 40%, dispersant 6%, toluene / ethyl acetate = 1/1) 24.1 parts Acrylic resin 34.8 parts (trade name BR -113, acid value 3.5 (mgKOH / g), solid content 40%, glass transition point 75 ° C., weight average molecular weight 30000, manufactured by Mitsubishi Rayon Co., Ltd.)
Toluene / methyl ethyl ketone = 50/50 (mass ratio) 41.1 parts

(Comparative Example 5)
The heat transfer sheet of Comparative Example 5 was heated in the same manner as in Example 1 except that the heat-fusible colored layer coating solution 1 was changed to one having the following composition under the production conditions of the heat transfer sheet produced in Example 1. It produced with eight types from which the application quantity of a meltable colored layer differs.
(Coating solution 10 for hot-melt coloring layer)
Colorant (carbon black dispersant, solid content 46%, blended carbon black 40%, dispersant 6%, toluene / ethyl acetate = 1/1) 24.1 parts Acrylic resin 34.8 parts (trade name BR -64, acid value 2 (mgKOH / g), solid content 40%, glass transition point 55 ° C., weight average molecular weight 65000, manufactured by Mitsubishi Rayon Co., Ltd.)
Toluene / methyl ethyl ketone = 50/50 (mass ratio) 41.1 parts

(Comparative Example 6)
The heat transfer sheet of Comparative Example 6 was heated in the same manner as in Example 1 except that the heat-fusible colored layer coating solution 1 was changed to one having the following composition under the preparation conditions of the heat transfer sheet prepared in Example 1. It produced with eight types from which the application quantity of a meltable colored layer differs.
(Coating liquid 11 for heat-meltable colored layer)
Colorant (carbon black dispersant, solid content 46%, blended with carbon black 40%, dispersant 6%, toluene / ethyl acetate = 1/1) 24.1 parts acrylic resin 46.3 parts (trade name BR -77, acid value 18.5 (mgKOH / g), solid content 30%, glass transition point 80 ° C., weight average molecular weight 65000, manufactured by Mitsubishi Rayon Co., Ltd.)
Toluene / methyl ethyl ketone = 50/50 (mass ratio) 29.6 parts

(Comparative Example 7)
The heat transfer sheet of Comparative Example 7 was heated in the same manner as in Example 1 except that the heat-fusible colored layer coating solution 1 was changed to one having the following composition under the preparation conditions of the heat transfer sheet prepared in Example 1. It produced with eight types from which the application quantity of a meltable colored layer differs.
(Coating liquid 12 for heat-meltable colored layer)
Colorant (carbon black dispersant, solid content 46%, blended carbon black 40%, dispersant 6%, toluene / ethyl acetate = 1/1) 24.1 parts Acrylic resin 34.8 parts (trade name BR -116, acid value 7 (mgKOH / g), solid content 40%, glass transition point 50 ° C., weight average molecular weight 45000, manufactured by Mitsubishi Rayon Co., Ltd.)
Toluene / methyl ethyl ketone = 50/50 (mass ratio) 41.1 parts

(Comparative Example 8)
The heat transfer sheet of Comparative Example 8 was heated in the same manner as in Example 1 except that the heat-fusible colored layer coating solution 1 was changed to one having the following composition under the preparation conditions of the heat transfer sheet prepared in Example 1. It produced with eight types from which the application quantity of a meltable colored layer differs.
(Coating liquid 13 for hot-melt coloring layer)
Colorant (carbon black dispersant, solid content 46%, blended carbon black 40%, dispersant 6%, toluene / ethyl acetate = 1/1) 24.1 parts Polyester resin 13.9 parts (trade name Byron 220, acid value less than 2 (mgKOH / g), solid content 100%, glass transition point 53 ° C., weight average molecular weight 5000, manufactured by Toyobo Co., Ltd.)
Toluene / methyl ethyl ketone = 50/50 (mass ratio) 62.0 parts

(Comparative Example 9)
The heat transfer sheet of Comparative Example 9 was heated in the same manner as in Example 1 except that the heat-fusible colored layer coating solution 1 was changed to one having the following composition under the preparation conditions of the heat transfer sheet prepared in Example 1. It produced with eight types from which the application quantity of a meltable colored layer differs.
(Coating liquid 14 for heat-meltable colored layer)
Colorant (carbon black dispersant, solid content 46%, blended carbon black 40%, dispersant 6%, toluene / ethyl acetate = 1/1) 24.1 parts Polyester resin 13.9 parts (trade name Byron 885, acid value less than 2 (mgKOH / g), solid content 100%, glass transition point 79 ° C., weight average molecular weight 8000, manufactured by Toyobo Co., Ltd.)
Toluene / methyl ethyl ketone = 50/50 (mass ratio) 62.0 parts

(Comparative Example 10)
The thermal transfer sheet of Comparative Example 10 was heated in the same manner as in Example 1 except that the thermal melt colored layer coating solution 1 was changed to one having the following composition under the production conditions of the thermal transfer sheet produced in Example 1. It produced with eight types from which the application quantity of a meltable colored layer differs.
(Coating solution 15 for heat-meltable colored layer)
Colorant (carbon black dispersant, solid content 46%, blended carbon black 40%, dispersant 6%, toluene / ethyl acetate = 1/1) 24.1 parts Polyester resin 13.9 parts (trade name Byron 240, acid value less than 2 (mgKOH / g), solid content 100%, glass transition point 60 ° C., weight average molecular weight 15000, manufactured by Toyobo Co., Ltd.)
Toluene / methyl ethyl ketone = 50/50 (mass ratio) 62.0 parts

(Comparative Example 11)
The heat transfer sheet of Comparative Example 11 was heated in the same manner as in Example 1 except that the heat-fusible colored layer coating solution 1 was changed to one having the following composition under the preparation conditions of the heat transfer sheet prepared in Example 1. It produced with eight types from which the application quantity of a meltable colored layer differs.
(Coating liquid 16 for heat-meltable colored layer)
Colorant (carbon black dispersant, solid content 46%, blended carbon black 40%, dispersant 6%, toluene / ethyl acetate = 1/1) 24.1 parts Polyester resin 13.9 parts (trade name Byron GK640, acid value less than 4 (mgKOH / g), solid content 100%, glass transition point 79 ° C., weight average molecular weight 18000, manufactured by Toyobo Co., Ltd.)
Toluene / methyl ethyl ketone = 50/50 (mass ratio) 62.0 parts

  Using the thermal transfer sheets obtained in the above-mentioned examples and comparative examples, the following methods were used to evaluate the blurring and blurring in printing, and the heat-melting colored layer and the back layer of the thermal transfer sheet were overlapped to face each other. The evaluation of the blocking situation (blocking resistance) between the heat-fusible colored layer and the back layer of the thermal transfer sheet after storage at a high temperature (60 ° C.) under a constant load, the release layer on the base sheet, A thermal transfer image is formed on the receiving layer of the intermediate transfer recording medium provided with the receiving layer by using the thermal transfer sheets obtained in the above examples and comparative examples, and the adhesiveness between the heat-fusible colored layer and the receiving layer is improved. Further, the receiving layer on which the thermal transfer image was formed was transferred to a card substrate (material is vinyl chloride) as a transfer target, and the adhesion between the card substrate and the receiving layer was examined.

(Shaping in printing)
A thin line pattern with a line width of about 0.17 mm {(1 inch / 300) × 2} and an interval of 1 mm is used for the receiving layer of the intermediate transfer recording medium under the following printing conditions using each thermal transfer sheet. Printing was performed in two patterns, one in the flow direction and the other in the direction perpendicular to the flow direction. Further, this pattern was used as a positive pattern, and a negative pattern corresponding to the positive pattern was also printed. The printed matter was evaluated by visually observing whether or not the image area was blurred.
(Printing conditions)
Thermal head: KGT-217-12MPL20 (manufactured by Kyocera Corporation)
-Heating element average resistance: 3195 (Ω)
・ Print density in the main scanning direction: 300 dpi
-Sub-scanning direction printing density: 300 dpi
-Applied power: 0.13 (w / dot)
・ One line cycle: 5 (msec.)
-Printing start temperature: 40 (° C)

<Preparation of intermediate transfer recording medium>
A transparent polyethylene terephthalate having a thickness of 12 μm is used as a base sheet, and the coating solution for the release layer shown below is applied to the surface with a gravure coater and dried, and the entire thickness of the base sheet is dried. A 0.8 μm release layer was formed.
(Peeling layer composition)
Acrylic resin (manufactured by Mitsubishi Rayon Co., Ltd., BR-83) 88 parts Polyester resin 1 part Polyethylene wax 11 parts Methyl ethyl ketone 50 parts Toluene 50 parts

On the release layer, a receiving layer coating solution shown below was applied and dried with a gravure coater, and a receiving layer having a thickness of 1.5 μm was formed at the time of drying to prepare an intermediate transfer recording medium.
(Receptive layer coating solution)
40 parts of vinyl chloride-vinyl acetate copolymer (VY-LFX manufactured by Union Carbide)
Acrylic silicone 2.0 parts Methyl ethyl ketone 50 parts Toluene 50 parts

  The evaluation of blurring and blurring in printing was evaluated for all of the eight types of thermal transfer sheets having different coating amounts of the heat-meltable colored layer produced in each example.

The standard for evaluation of the blur in the above printing is as follows.
○: Good with no slippage.
Δ: Partially blurred, but readable.
X: There is an overall slip and it is defective.

(Scratch in printing)
Printing was performed in the same manner as the printing conditions for the above-described printing. The printed matter was visually evaluated for the presence or absence of blurring in the image area.
The criteria for evaluation of blur in the above printing are as follows.
○: No blurring and good.
Δ: Partially blurred but readable.
X: Scratch is observed as a whole and it is defective.

(Blocking resistance)
The heat-fusible colored layer and the back layer of each heat transfer sheet are overlapped with each other on the heat transfer sheets of Examples and Comparative Examples prepared above, and a load of 20 g / cm ² is applied and stored at 60 ° C. for 100 hours. did. The state of blocking between the heat-meltable colored layer and the back layer of the thermal transfer sheet after storage was visually observed and evaluated according to the following criteria. However, the thermal transfer sheet used in this case was limited to one with a coating amount of 1.0 g / m ² of the heat-meltable colored layer of the thermal transfer sheet of each example.
(Double-circle): The heat-meltable colored layer does not transfer to the back layer side at all, and there is no blocking between the heat-meltable colored layer and the back layer, which is very good.
◯: There was some resistance when peeling the overlapping thermal transfer sheets, but the hot-melt colored layer hardly transferred to the back layer side, which is a good level.
Δ: There is resistance when the overlapping thermal transfer sheets are peeled off, and the heat-meltable colored layer is slightly transferred to the back layer side, but it is at a practical level.
X: When peeling the overlapping thermal transfer sheet, the resistance is large, and the hot-melt colored layer is transferred in a considerable amount to the back layer side, which is defective.
XX: When peeling the overlapped thermal transfer sheet, the resistance is too high, and if it is tried to peel off forcibly, the thermal transfer sheet is destroyed and the level of defect is high.

(Adhesiveness between heat-meltable colored layer and receptor layer (intermediate medium adhesiveness))
In the same way as the conditions printed during the above-mentioned blurring in printing, each thermal transfer sheet is used for the receiving layer of the intermediate transfer recording medium, a test pattern is printed, and the adhesiveness between the hot-melt colored layer and the receiving layer The cellophane tape was affixed to the print part by rubbing once with a thumb and immediately peeled off at a 180 ° peeling angle to examine the adhesion. However, the thermal transfer sheet used in this case was limited to one with a coating amount of 1.0 g / m ² of the heat-meltable colored layer of the thermal transfer sheet of each example.
The evaluation criteria are as follows.
(Double-circle): There is no thing peeled off visually and it is very favorable.
○: The material that peels off visually is hardly recognized and is good.

(Adhesion between card substrate and receiving layer (card adhesion))
A test pattern is printed on each receptor layer of the intermediate transfer recording medium, using the thermal transfer sheet, in the same manner as the conditions printed during the above-described slipping in the printing, and the receptor layer printed is a card substrate. Transfer to the transfer target, and adhere the transferred receiving layer and the card substrate with the cellophane tape on the receiving layer surface by rubbing one reciprocating with a thumb, immediately peel off at 180 degree peeling angle, The adhesion was examined. Transfer of the receptor layer to the transfer medium was performed by heating and pressing with a heat roll. However, the thermal transfer sheet used in this case was limited to one with a coating amount of 1.0 g / m ² of the heat-meltable colored layer of the thermal transfer sheet of each example.
The evaluation criteria are as follows.
(Double-circle): There is no thing peeled off visually and it is very favorable.
○: The material that peels off visually is hardly recognized and is good.
X: The receptor layer formed with an image is visually observed on the cellophane tape side, and the adhesion between the receptor layer and the card substrate is poor.

Each evaluation result is shown in Table 1.

In evaluation of blurring and blurring in printing, in Examples 2 to 4, the coating amount when the hot-melt colored layer was dried was 0.2 g / m ² , 0.4 g / m ² , 0.6 g / m ² , 0 .8 g / m ² , 1.0 g / m ² , 1.2 g / m ² , 1.4 g / m ² , 1.6 g / m ² , when viewed at 8 levels, 0.6 g / m ² to The coating amount was 1.2 g / m ² and there was no practical problem. Also with respect to the first embodiment, the coating amount of the dry heat-meltable colored layer in the range of ^{0.4g / m 2 ~1.4g / m 2} , blur in printing, collapse was intended no practical problem . On the other hand, all of Comparative Examples 1 to 11 are defective because printing slippage occurs at an application amount of 1.2 g / m ² .

  In the evaluation of blocking resistance, Examples 2 to 4 are practically problematic levels. Regarding Examples 1 and 5, the KOH value of the acrylic resin used in the hot-melt colored layer is 15 (mgKOH / g) As described above, the heat-meltable colored layer hardly transferred to the back layer side, which was a good level.

DESCRIPTION OF SYMBOLS 1 Thermal transfer sheet 2 Base material sheet 3 Release layer 4 Heat-meltable colored layer 5 Back surface layer 6 Image 7 Sublimation transfer image 8 Transfer object 9 Image formation 10 Intermediate transfer recording medium 11 Base material sheet 12 Peeling layer 13 Receiving layer 14 Back layer

Claims (6)

  A thermal transfer sheet in which a heat-fusible colored layer capable of being transferred by heat is provided on at least a part of one surface of a base sheet via a release layer, wherein the heat-fusible colored layer includes at least an acrylic resin and a polyester. A thermal transfer sheet comprising a resin and a colorant, wherein the acrylic resin has a KOH value of 2 (mgKOH / g) or more, and the polyester resin has an acid value of less than 2 (mgKOH / g).   2. The thermal transfer sheet according to claim 1, wherein the acrylic resin contained in the heat-meltable colored layer has a KOH value of 15 (mgKOH / g) or more.   The thermal transfer sheet according to claim 1 or 2, wherein the acrylic resin contained in the heat-meltable colored layer is an amine-modified acrylic resin.   The acrylic resin and the polyester resin contained in the heat-fusible colored layer are mixed at a mass ratio of 85:15 to 60:40, according to any one of claims 1 to 3. Thermal transfer sheet. The thermal transfer sheet according to any one of claims 1 to 4 heat-meltable colored layer of the can, the amount of coating in the dry state is characterized by a 0.6 to 1.2 g / m ^2. Using the thermal transfer sheet according to any one of claims 1 to 5, for the intermediate transfer recording medium having a receptive layer having releasability on one surface of the base sheet, the receptive layer is thermally meltable. An image forming method comprising: forming an image by transferring an image-formed receiving layer of the intermediate transfer recording medium to a transfer target after transferring a colored layer and forming an image.

Images