JP2012066530A - Thermal transfer sheet and image forming method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal transfer sheet having a function of excellent print quality and high adhesiveness to a transfer medium and having a heat-fusible colored layer on a base sheet, and an image forming method using the thermal transfer sheet. For the purpose.
SOLUTION: In a thermal transfer sheet in which a heat-fusible colored layer 4 that can be transferred by heat is provided on at least a part of one surface of a base sheet 2 via a release layer 3, the release layer 3 is provided. It has a silicone-modified resin having an epoxy group, a curing catalyst, and a polyester resin, and the heat-meltable colored layer 4 is composed of a resin binder containing at least a vinyl chloride-vinyl acetate copolymer and a colorant.
[Selection] Figure 1

Description

  The present invention relates to a thermal transfer sheet provided with a heat-fusible colored layer on a base sheet having excellent printing quality and high adhesion to a transfer medium, and an image forming method using the thermal transfer sheet It is.

  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.

  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 release layer is particularly required. In other words, it is possible to transfer to the receiving layer of the intermediate transfer recording medium without blurring or blurring of the print, and to adhere to the receiving layer of the printed portion, and to adhere to the transferred receiving layer and the transfer target. It is required to be sufficient. However, there is a problem that there is nothing that sufficiently satisfies the performance of the release layer.
JP-A-62-238791 Japanese Unexamined Patent Publication No. 7-52522

  Accordingly, the present invention solves the above-described problems, has a function of excellent print quality and high adhesion to a transfer target, and has a function of providing a heat-meltable colored layer on a substrate 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 release layer has a silicone-modified resin having an epoxy group, a curing catalyst, and a polyester resin, and the heat-meltable colored layer is at least vinyl chloride-vinyl acetate. It is characterized by comprising a resin binder containing a copolymer and a colorant.

According to a second aspect of the present invention, the heat-meltable colored layer according to the first aspect comprises a first component comprising a vinyl chloride-vinyl acetate copolymer as a resin binder, and a second component comprising an amine-modified acrylic resin. Including the component, the amine-modified acrylic resin is contained in a ratio of 5 to 15% by mass with respect to the whole resin of the first component. In addition, as the third aspect of the present invention, the release layer described in the first or second aspect includes the polyester resin in a proportion of 5 to 20% by mass with respect to the solid content constituting the release layer. It is characterized by being. As a fourth aspect of the present invention, the heat-meltable colored layer according to any one of the first to third aspects is characterized in that the coating amount is 0.6 to 1.2 g / m ² in a dry state. To do.

  The image forming method according to claim 5 of the present invention uses the thermal transfer sheet according to any one of the above, and an 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.

  In 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 blurred, has excellent print quality, and has high adhesion between the transfer target and the print portion. In addition, using the above-described thermal transfer sheet, after an image is formed by transferring a heat-fusible colored layer to an intermediate transfer recording medium having a releasable receptive layer 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.

(Base material 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. The release layer is composed of a silicone-modified resin having an epoxy group, a curing catalyst, and a polyester resin. That is. As resin used for a mold release layer, what hardened silicone modification resin which has an epoxy group, and polyester resin are used. 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. Celltop 226 (manufactured by Daicel Chemical Co., Ltd.), celltop 227 (manufactured by Daicel Chemical Industries, Ltd.), etc. are available as commercially available epoxy-modified silicone-modified resins suitably used for the release layer of the present invention. It is.

  A curing catalyst is used to cure the silicone-modified resin having the epoxy group. The curing catalyst is not particularly limited, and examples thereof include aluminum compounds such as aluminum alkoxide and aluminum chelate, N-β-aminoethyl-γ-aminopropyltrimethoxysilane, N-β-aminoethyl-γ-aminopropyl. Examples thereof include amine-based silane coupling agents such as methyldimethoxysilane.

  The polyester resin contained in the release layer preferably has a glass transition point of 50 ° C to 70 ° C and a number average molecular weight of 2000 to 4000. Byron 220 (manufactured by Toyobo Co., Ltd.) or the like is available as a commercially available polyester resin suitably used for the release layer of the present invention. The polyester resin is a grade having a low glass transition point, and as described below, the content of the polyester resin in the release layer is set in a specific range, in other words, it is added in a relatively small amount. The release layer is mainly composed of a cured product of a silicone-modified resin having an epoxy group and a polyester resin, but both of these have low compatibility, that is, incompatibility. Each can be demonstrated, and the heat-fusible colored layer is smooth from the release layer while maintaining the adhesion between the base sheet and the release layer (due to the cured silicone-modified resin having an epoxy group) at the heating temperature in printing. And transferred to the mold (by polyester resin).

  The release layer preferably contains the polyester resin in a proportion of 5 to 20% by mass with respect to the solid content constituting the release layer. That is, it is preferable to contain said polyester resin in the ratio of 5-20 mass% with respect to the solid content which the silicone modified resin which has an epoxy group in a mold release layer hardened | cured with the curing catalyst. When the content of the polyester resin is less than 5% by mass, the transferability of the heat-meltable colored layer is inferior and printing blurring or blurring occurs. Further, if the content of the polyester resin exceeds 20% by mass, the characteristics of the cured silicone-modified resin cannot be sufficiently exhibited, so that the adhesion between the release layer and the base sheet is lowered, and the heat in the thermal transfer sheet The foil-holding property of the meltable colored layer is lowered, and there arises a problem that the heat-meltable colored layer is easily peeled off from the substrate sheet during storage.

The release layer is prepared by dissolving or dispersing the silicone-modified resin having the epoxy group, the curing catalyst, and the polyester resin in a solvent to prepare a coating solution, and applying and drying the coating solution to form a release layer. It is formed. The coating amount of the release layer is about 0.1 to 5.0 g / m ² when dried.

(Hot-melting colored layer)
The heat-meltable colored layer has a first binder resin, a second binder resin, and a colorant.
As the first binder resin, a vinyl chloride-vinyl acetate copolymer can be used.

The vinyl chloride-vinyl acetate copolymer preferably has a glass transition point of 70 ° C. to 90 ° C. and a weight average molecular weight of 15,000 to 30,000.
As the first binder resin in the heat-meltable colored layer, an acrylic resin can be added in addition to the vinyl chloride-vinyl acetate copolymer. Thereby, it is possible to obtain a thermal transfer sheet that is less affected by print blurring and blurring due to fluctuations in the coating amount of the heat-meltable colored layer. The acrylic resin used as the first component is an acrylic resin that does not have an amino group. For example, polyacrylic acid, polymethacrylic acid, polyacrylic acid alkyl ester, polymethacrylic acid, and a heat composed of a copolymer thereof. A plastic resin can be preferably used. The weight average molecular weight (Mw) is 10,000 to 50,000, preferably 25,000 to 40,000. 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.

  The acrylic resin preferably has a glass transition point of 90 to 110 ° C. When the glass transition point is low, a problem occurs in storage stability, and when the glass transition point is too high, printing sensitivity is insufficient.

An amine-modified acrylic resin can be used as the second binder resin.
Since the amine-modified acrylic resin is contained in a ratio of 5 to 15% by mass with respect to the entire resin of the first component of the heat-meltable colored layer, the amino group reacts with the epoxy group in the release layer. And it can couple | bond and can stabilize the peeling force in a thermal transfer sheet. The peeling force is the adhesive strength between the release layer and the heat-meltable colored layer. As a result, the heat-meltable colored layer is not peeled off from the substrate sheet during handling of the thermal transfer sheet other than during thermal printing, and there is no “scratch” in thermal transfer printing, and sharp printing is obtained. Further, the amine-modified acrylic resin has a high molecular weight having a weight average molecular weight of about 45,000, and increases the film strength of the heat-meltable colored layer. When the content ratio of the amine-modified acrylic resin is less than the above range, the peeling force between the release layer and the heat-meltable colored layer becomes unstable, and slippage in printing tends to occur. On the other hand, when the content of the amine-modified acrylic resin is larger than the above range, the peeling force between the release layer and the heat-meltable colored layer is increased, and “scratch” is likely to occur in printing. The “scratch” is a printing defect in which the heat-meltable colored layer cannot be transferred to all or a part of the area to which the heat-meltable colored layer is originally 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.

The amine-modified acrylic resin contained in the hot-melt colored layer has the following functions.
When forming the release layer in the production of the thermal transfer sheet, if the drying temperature after application changes, the peeling force between the release layer and the heat-melting colored layer will change, causing the printing to become uneven or smudged. Is likely to occur. That is, when the drying temperature of the release layer is high, the reaction of the epoxy group in the release layer proceeds, the peeling force from the heat-meltable colored layer becomes low, and the printing is liable to occur. On the other hand, the amine-modified acrylic resin is contained in the heat-meltable colored layer, the unreacted epoxy group of the release layer reacts with the amine-modified acrylic resin, and the heat-meltable colored layer is released from the release layer. The peeling force of the paper was increased to prevent printing slipping. In the present invention, the release layer has not only a silicone-modified resin having an epoxy group and a curing catalyst, but also a low molecular weight polyester resin. I was able to prevent it.

  In addition, if the drying temperature at the time of forming the release layer is low, unreacted epoxy groups increase in the release layer, and the unreacted epoxy groups react with the heat-fusible colored layer to release the release layer. And the heat-fusible colored layer are easily peeled off, and the printing is liable to be blurred. On the other hand, the amine-modified acrylic resin is contained in the heat-meltable colored layer in a proportion of 0.2 to 15% by mass with respect to the entire first component resin of the heat-meltable colored layer. The unreacted epoxy group reacts with the amino group of the amine-modified acrylic resin of the heat-fusible colored layer, and the peeling force between the release layer and the heat-fusible colored layer can be adjusted appropriately. We were able to prevent blur. However, in this case as well, the release layer has not only a silicone-modified resin having an epoxy group and a curing catalyst, but also a low molecular weight polyester resin. The function of the heat-meltable colored layer is demonstrated with an assist.

By adding a small amount of amine-modified acrylic resin to the vinyl chloride-vinyl acetate copolymer in the heat-meltable colored layer as described above, a reaction occurs with the epoxy group of the silicone-modified resin contained in the release layer, and thermal transfer The peeling force at the time becomes a little heavy, and it becomes difficult for printing to occur. Further, since the amine-modified acrylic resin contained in the heat-meltable colored layer reacts with the epoxy group remaining in the release layer to eliminate the epoxy group, a stable peeling force in thermal transfer can be ensured. The vinyl chloride-vinyl acetate copolymer enhances the adhesiveness with the intermediate transfer recording medium in the heat-meltable colored layer and further the adhesiveness with the transfer target.

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, film formability cannot be obtained, and this causes a reduction in scratching 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. Further, when the coating amount exceeds 1.2 g / m ² , printing slippage tends to occur during printing transfer.

(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, and the intermediate transfer recording medium provided with a releasable receptive layer on one surface of the base sheet is provided with the receptive layer. After the heat-meltable colored layer is transferred to form an image, the image-formed receiving layer is transferred from an intermediate transfer recording medium to a transfer medium 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.
(Base material 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. Each of the seven levels was coated and dried to form a heat-fusible colored layer, and the thermal transfer sheet of Example 1 was produced with seven different coating amounts of the heat-fusible colored layer.

  In the release layer in Example 1, the polyester resin is added at a ratio of 5% by mass with respect to the solid content constituting the release layer. In the heat-meltable colored layer in Example 1, the amine-modified acrylic resin is contained in a proportion of 11.1% by mass with respect to the vinyl chloride-vinyl acetate copolymer.

(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 for release layer 1)
Silicone-modified acrylic resin (silicone-modified acrylic resin having an epoxy group, Cell Top 226, manufactured by Daicel Chemical Industries, Ltd., solid content 50%) 40 parts Aluminum catalyst (Cell Top CAT-A, manufactured by Daicel Chemical Industries, Ltd., 10% solids)
10 parts Polyester resin (Byron 220, glass transition point 67 ° C., number average molecular weight 3000, manufactured by Toyobo Co., Ltd.) 1.05 parts Methyl ethyl ketone 24 parts Toluene 24 parts

(Coating liquid 1 for meltable colored layer)
Colorant (carbon black dispersant, solid content 46%, blended carbon black 40%, dispersant 6%, toluene / ethyl acetate = 1/1) 17.4 parts vinyl chloride-vinyl acetate copolymer 33. 3 parts (Brand name Solvain CL, solid content 30%, glass transition point 75 ° C., weight average molecular weight 20000, manufactured by Nissin Chemical Industry Co., Ltd.)
2.47 parts of amine-modified acrylic resin (solid content 45%, glass transition point 90 ° C., weight average molecular weight 45000, manufactured by DIC)
Toluene / methyl ethyl ketone = 50/50 (mass ratio) 46.83 parts

(Example 2)
The thermal transfer sheet of Example 2 was heat-meltable in the same manner as in Example 1 except that the release layer coating liquid 1 was changed to the following composition under the production conditions of the thermal transfer sheet produced in Example 1. It produced with seven types from which the application quantity of a colored layer differs.
(Release layer coating solution 2)
Silicone-modified acrylic resin (silicone-modified acrylic resin having an epoxy group, Cell Top 226, manufactured by Daicel Chemical Industries, Ltd., solid content 50%) 40 parts Aluminum catalyst (Cell Top CAT-A, manufactured by Daicel Chemical Industries, Ltd., 10% solids)
10 parts Polyester resin (Byron 220, glass transition point 67 ° C., number average molecular weight 3000, manufactured by Toyobo Co., Ltd.) 4.2 parts Methyl ethyl ketone 23 parts Toluene 23 parts

  In addition, as for the release layer in Example 2, the polyester resin is added in the ratio of 20 mass% with respect to solid content which comprises a release layer.

(Example 3)
The thermal transfer sheet of Example 3 was heat-meltable in the same manner as in Example 1 except that the release layer coating liquid 1 was changed to the following composition under the production conditions of the thermal transfer sheet produced in Example 1. It produced with seven types from which the application quantity of a colored layer differs.
(Coating liquid 3 for release layer)
Silicone-modified acrylic resin (silicone-modified acrylic resin having an epoxy group, Cell Top 226, manufactured by Daicel Chemical Industries, Ltd., solid content 50%) 40 parts Vinyl chloride-vinyl acetate copolymer resin 4 parts (Solvine A, solid content 100%, glass transition point 76 ° C., number average molecular weight 30000, manufactured by Nissin Chemical Industry Co., Ltd.)
Aluminum catalyst (Cell Top CAT-A, Daicel Chemical Industries, solid content 10%)
10 parts Polyester resin (Byron 220, glass transition point 67 ° C., number average molecular weight 3000, manufactured by Toyobo Co., Ltd.) 1.25 parts Methyl ethyl ketone 24 parts Toluene 24 parts

  In addition, as for the release layer in Example 3, the polyester resin is added in the ratio of 5 mass% with respect to solid content which comprises a release layer.

Example 4
The thermal transfer sheet of Example 3 was heat-meltable in the same manner as in Example 1 except that the release layer coating liquid 1 was changed to the following composition under the production conditions of the thermal transfer sheet produced in Example 1. It produced with seven types from which the application quantity of a colored layer differs.
(Release layer coating solution 4)
Silicone-modified acrylic resin (silicone-modified acrylic resin having an epoxy group, Cell Top 226, manufactured by Daicel Chemical Industries, Ltd., solid content 50%) 40 parts Vinyl chloride-vinyl acetate copolymer resin 4 parts (Solvine A, solid content 100%, glass transition point 76 ° C., number average molecular weight 30000, manufactured by Nissin Chemical Industry Co., Ltd.)
Aluminum catalyst (Cell Top CAT-A, Daicel Chemical Industries, solid content 10%)
10 parts Polyester resin (Byron 220, glass transition point 67 ° C., number average molecular weight 3000, manufactured by Toyobo Co., Ltd.) 5 parts Methyl ethyl ketone 24 parts Toluene 24 parts

  In addition, as for the release layer in Example 4, the polyester resin is added in the ratio of 20 mass% with respect to solid content which comprises a release layer.

(Comparative Example 1)
The thermal transfer sheet of Comparative Example 1 was heat-meltable in the same manner as in Example 1 except that the release layer coating liquid 1 was changed to the following composition under the production conditions of the thermal transfer sheet produced in Example 1. It produced with seven types from which the application quantity of a colored layer differs.
(Coating solution 5 for release layer)
Silicone-modified acrylic resin (silicone-modified acrylic resin having an epoxy group, Cell Top 226, manufactured by Daicel Chemical Industries, Ltd., solid content 50%) 40 parts Vinyl chloride-vinyl acetate copolymer resin 4 parts (Solvine A, solid content 20%, glass transition point 76 ° C., number average molecular weight 30000, manufactured by Nissin Chemical Industry Co., Ltd.)
Aluminum catalyst (Cell Top CAT-A, Daicel Chemical Industries, solid content 10%)
10 parts Methyl ethyl ketone 24 parts Toluene 24 parts

(Comparative Example 2)
The heat transfer sheet of Comparative Example 2 was heated in the same manner as in Comparative 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 Comparative Example 1. It produced with seven types from which the application quantity of a meltable colored layer differs.
(Coating liquid 2 for meltable colored layer)
Colorant (carbon black dispersant, solid content 46%, blended with carbon black 40%, dispersant 6%, toluene / ethyl acetate = 1/1) 17.4 parts vinyl chloride-vinyl acetate copolymer 30. 0 parts (Brand name Solvein CL, solid content 30%, glass transition point 70 ° C., number average molecular weight 25000, manufactured by Nissin Chemical Industry Co., Ltd.)
Toluene / methyl ethyl ketone = 50/50 (mass ratio) 52.6 parts

Using the thermal transfer sheets obtained in the above examples and comparative examples, the following methods were used to evaluate the slippage and blurring in printing, as well as the intermediate transfer recording medium provided with a release layer and a receiving layer on the base sheet. Using the thermal transfer sheets obtained in the above Examples and Comparative Examples as the receptor layer, a thermal transfer image is formed, the adhesion between the heat-meltable colored layer and the receptor layer is examined, and the receptor having the thermal transfer image formed thereon The layer was transferred to a card substrate (material is vinyl chloride) which is a transfer target, and the adhesion between the card substrate and the receiving layer was examined. In addition, the heat transferable coloring layer of each of the above examples has a coating amount of 1.0 g / m ² and is different in drying temperature in the formation of the release layer, and whether or not there are blurring and blurring in printing. The peelability was evaluated.

(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 seven types of thermal transfer sheets having different coating amounts of the heat-meltable colored layers prepared 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.

(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 the meltable colored layer of the thermal transfer sheet of each example being 1.0 g / m ² .
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.
○: Nothing peels off visually, which 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.

(Peelability)
In the same manner as the printing conditions during the above-described printing, printing is performed in two patterns using each thermal transfer sheet on the receiving layer of the intermediate transfer recording medium. The presence or absence of the image and the presence or absence of blurring in the image area were visually observed and evaluated. However, in the examples and comparative examples, the thermal transfer sheet used was limited to one type having a coating amount of the heat-fusible colored layer of the thermal transfer sheet of each example of 1.0 g / m ² and the thermal transfer sheet of each example. The drying conditions for forming the release layer were prepared by drying at a drying temperature of 90 ° C., 110 ° C. (normal conditions), and 130 ° C. for 1 minute, respectively. Using these thermal transfer sheets, the presence or absence of blurring of the image line portion in the printed matter and the presence or absence of blurring of the image line portion were evaluated according to the following criteria to examine the peelability.
◯: There is no blurring or blurring in the image area of the printed matter, which is good.
Δ: Slight blurring or blurring of the image area is recognized on the printed matter.
X: The image line portion of the printed matter is blurred or blurred, which is defective.

Each evaluation result is shown in Table 1.

  In the evaluation of peelability, in Examples 1 to 4, when the drying temperature of the release layer is changed from the normal condition (110 ° C.), slight printing blurring and blurring occur, but there is no practical problem. is there. On the other hand, in Comparative Examples 1 and 2, when the drying temperature is lower than usual (at 90 ° C.), the peeling force between the release layer and the heat-meltable colored layer increases, resulting in print blurring. In Comparative Example 2, when the drying temperature is lower than usual (at 90 ° C.), the peeling force between the release layer and the heat-meltable colored layer becomes too large, and the thermal transfer sheet is adhered to the intermediate transfer recording medium. End up.

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 (5)

  In a thermal transfer sheet provided on at least a part of one surface of the base sheet with a heat-meltable colored layer that can be transferred by heat via a release layer, the release layer has a silicone-modified resin having an epoxy group; A thermal transfer sheet comprising a curing catalyst and a polyester resin, wherein the heat-fusible colored layer is composed of a resin binder containing at least a vinyl chloride-vinyl acetate copolymer and a colorant.   The heat-fusible colored layer includes, as a resin binder, a first component composed of a vinyl chloride-vinyl acetate copolymer, and a second component composed of an amine-modified acrylic resin. 2. The thermal transfer sheet according to claim 1, wherein the thermal transfer sheet is contained at a ratio of 5 to 15% by mass with respect to the whole resin of one component.   The thermal transfer sheet according to claim 1 or 2, wherein the release layer contains a polyester resin in a proportion of 5 to 20% by mass with respect to the solid content constituting the release layer. . Thermal transfer sheet heat-meltable colored layer of the can, the amount of coating in the dry state is described in any one of claims 1 to 3, characterized in that it is 0.6 to 1.2 g / m ^2. Using the thermal transfer sheet according to any one of claims 1 to 4, for the intermediate transfer recording medium having a receptive layer having releasability on one surface of the substrate 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.

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