JP2003025733A - Thermal transfer recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal transfer recording medium capable of forming an image having a high resolution and a durability. SOLUTION: The thermal transfer recording medium comprises a thermal transfer recording layer obtained by melting or softening at least a base by a heat and transferring the base. In this medium, the thermal transfer recording layer 3 containing colorless or pale fine particles, a coloring pigment and a resin as main components is the thermal transfer recording medium 1 in which at least three colors of cyan, magenta and yellow and a white concealing layer 4 are sequentially repeatedly individually coated along a longitudinal direction of a support, compositions for forming the thermal transfer recording layers of the respective colors contain the coloring pigment of 19 to 30 pts.wt. the resin of 40 to 80 pts.wt. and the colorless or pale fine particles of 1 to 30 pts.wt. in a blending composition with respect to its total solid content of 100 pts.wt., a film thickness is 0.1 to 1.0 μm, and further resins of the thermal transfer recording layers of the respective colors and the white concealing layer are amorphous organic polymers of the same type.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to thermal transfer of a thermal transfer recording layer containing a coloring pigment with a thermal head printer onto an intermediate transfer foil having an image receiving layer capable of transferring, and more specifically, at least two or more colors are superposed. Is a thermal transfer recording medium for thermal transfer recording in which a gradation color image by area gradation is formed, and the image-receiving layer of the printed intermediate transfer medium is transferred to a target transfer object, particularly metal and glass. The present invention relates to a thermal transfer recording medium which can be satisfactorily transferred to an article.

[0002]

2. Description of the Related Art Conventionally, a sublimation transfer method and a melt transfer method are known as a thermal transfer recording method for forming a gradation image using a thermal head printer.

In the sublimation transfer method, a thermal transfer recording medium having a thermal transfer recording layer composed of a sublimable (heat transferable) dye and a binder resin is provided on a support, and a thermal transfer recording medium is superposed on an image receiving sheet, and thermal transfer recording is performed according to the amount of heat of the thermal head. The sublimation dye in the layer is transferred onto the image-receiving sheet to form a gradation image. However, when an image is formed using such a sublimable (heat transferable) dye, the formed image has poor durability, and its use in fields requiring heat resistance and light resistance is limited. In addition, since the thermal recording sensitivity is lower than that of the melt transfer method, it is not suitable as a high-speed recording material using a high resolution thermal head that is expected to be put to practical use in the future because it is smaller and lighter in the printer driven by batteries such as dry batteries. have.

On the other hand, in the melt transfer system, a thermal transfer recording medium having a thermally fusible ink transfer layer composed of a coloring material such as a pigment or a dye and a binder such as a wax on a support is used to heat a thermal head or the like. This is a system in which energy is applied to the device according to image information and the ink transfer layer is fused on the image receiving sheet to form an image. The image formed by the melt transfer method has high density and excellent sharpness, and is suitable for recording binary images such as characters and line drawings. Further, a thermal transfer recording medium composed of yellow, magenta, cyan and black is used to form an image on the image receiving sheet so that a color image can be formed. Such a thermal transfer recording medium for forming a color image is disclosed in Japanese Examined Patent Publication No. 63-6502.
There is No. 9 publication. On the other hand, in the thermal transfer recording method,
In addition to the above-mentioned direct transfer to the image receiving sheet to be the transferred material to form the final transferred material, an image receiving layer which can be peeled off without directly transferring the image from the thermal transfer recording medium to the intended transferred material is provided. There is known a method in which an image composed of a thermal transfer recording layer is transferred onto an image receiving layer of an intermediate medium, and thereafter, the image (thermal transfer recording layer) is retransferred together with the image receiving layer to a target transfer target. Hereinafter, this will be referred to as a retransfer method.

Using this method, various cards such as cash cards, credit cards, various ID cards, plastic cards such as prepaid cards, paper such as government postcards and passports, or cloth such as T-shirts and handkerchiefs can be imaged. Can be transferred. In the case of this method, it is possible to obtain a high-resolution image irrespective of the material and surface condition of the transfer target compared to the method of directly printing on the transfer target, and to print on a non-smooth transfer target. There are merits such as being possible. However, depending on the material to be transferred, when the intermediate transfer medium to which the image is finally transferred is transferred to the target material to be transferred, the adhesion to the image receiving layer of the intermediate transfer medium and the printed thermal transfer ink layer is improved. As described above, it is necessary to apply the primer layer ink to the surface of the transfer target in advance to form the primer layer. In many cases, such pretreatment for the transferred material is very troublesome, and depending on the transferred material, the pretreatment may not be possible.

In addition to conventional plastic plates such as prepaid cards, cash cards, credit cards, various ID cards, etc., thermal transfer recording media capable of accommodating transfer materials made of various materials such as metal plates and glass plates and capable of excellent printing. Was never before.

[0007]

[Problems to be Solved by the Invention] Japanese Patent Publication No. 63-65
In the case of the thermal transfer recording medium described in Japanese Patent No. 029, since a crystalline wax having a low melting point is used as a binder for the ink layer, the bleeding of the ink easily causes a reduction in the resolution. In addition, the adhesive strength and film strength of the transferred image are weak, and if the image portion is rubbed hard by hand, the image portion will be removed. Various proposals have been made as methods for solving such a phenomenon. For example, Japanese Patent Laid-Open No. 61-244592 discloses 65
A thermal transfer recording medium has been proposed which has a thermal ink layer comprising an amorphous polymer in an amount of at least 100%, a release material and a colorant. However, since the thermal transfer recording medium described in JP-A-61-244592 also contains the crystalline wax, the adhesive strength of the portion where the overprinting of each color is performed is insufficient.

In the retransfer method, the weak adhesive strength is re-transferred together with the image receiving layer, so that the transferred image receiving layer serves as a protective layer and is covered to some extent. The image comes off.
Further, no matter how strong the adhesive strength and film strength of the ink layer and the image receiving layer, which are the transferred images, are, if the adhesive strength with the transferred material is not strong, they will peel off from the transferred material. Therefore, it is necessary to preliminarily apply a primer layer or the like to the transferred material as a pretreatment to strengthen the adhesive strength between the transferred material and the transferred image and the image receiving layer.

[0009] In addition, a transfer target colored other than white, a transfer target having a luster such as metal or metal vapor deposition, or a transparent transfer target such as glass or transparent plastic can be used in any full color. When transferring the image, it is very difficult to apply a white layer only to the part where the image is transferred as a pretreatment, but it is very difficult to provide a full-color image at any position other than the white part, or it is transparent. Or, a metallic image could not be provided at an arbitrary position.

The present invention has been made in view of the above-mentioned problems of the prior art, and reduces the resolution due to ink bleeding due to the use of a crystalline wax having a low melting point as a binder for an ink layer. To prevent this, and when using a wax, the durability is insufficient when the transferred image is rubbed by hand, improving the point that the image is easy to be lost and increasing the durability. For the purpose of providing a thermal transfer recording medium that can be sufficiently achieved, in particular, in addition to paper and plastic cards, pretreatment such as primer coating is applied to a transparent or metallic glossy transfer target made of glass or metal. It is an object of the present invention to provide a thermal transfer recording medium that can form an arbitrary image without using it.

[0011]

As a result of intensive studies, the present inventors have made it possible to solve the above-mentioned problems by using a melt transfer method. That is, the invention according to the first aspect is a thermal transfer recording medium having a thermal transfer recording layer that is melted or softened by heat and transferred to at least one of the substrates, and preprinted on an intermediate transfer medium having at least a transferable image receiving layer, In the thermal transfer recording medium used in the thermal transfer recording method for transferring the image-receiving layer of the printed intermediate transfer medium to a target transfer object, a thermal transfer recording layer mainly composed of a color pigment, a resin, and colorless or light-colored fine particles is used. A composition for forming a thermal transfer recording layer of each color, which is a thermal transfer recording medium in which at least three colors of cyan, magenta, and yellow and a white hiding layer are separately and sequentially coated in the longitudinal direction of a support. However, with respect to the total solid content of 100 parts by weight, the coloring pigment is 19 to 30 parts by weight and the resin is 40 to 80 parts by weight.
By weight, colorless or light-colored fine particles are contained in an amount of 1 to 30 parts by weight, and the film thickness is 0.2 to 1.0 μm. Furthermore, the resins of the thermal transfer recording layer and the white hiding layer of each color are the same type of amorphous organic. It is a thermal transfer recording medium characterized by being a polymer.

According to a second aspect of the present invention, the thermal transfer recording layer is coated along the longitudinal direction of the support with at least three colors of cyan, magenta, and yellow, and a white hiding layer and a transparent adhesive layer are sequentially and repeatedly coated. The thermal transfer recording medium according to claim 1, wherein the thermal transfer recording medium is provided separately.

According to a third aspect of the invention, the resin in the thermal transfer recording layer and the white hiding layer has a sphere method softening point of 70.
3. The thermal transfer recording medium according to claim 1, wherein the thermal transfer recording medium is an epoxy resin in the range of 150 ° C. to 150 ° C.

In the invention according to claim 4, the resin in the thermal transfer recording layer and the white hiding layer has a glass transition point of 40.
The thermal transfer recording medium according to claim 1 or 2, which is an acrylic resin in the range of -100 ° C.

In the invention according to claim 5, the resin in the thermal transfer recording layer and the white hiding layer has an average molecular weight of 1
The thermal transfer recording medium according to claim 1 or 2, which is a vinyl chloride vinyl acetate copolymer resin in the range of 20,000 to 20,000.

The invention according to claim 6 is the thermal transfer recording medium according to claims 1 and 2, wherein the colorless or light-colored fine particles in the thermal transfer recording layer are silica.

The invention according to claim 7 is the thermal transfer recording medium according to claim 1 or 2, wherein the transparent adhesive layer contains a resin of the same kind as the resin in the thermal transfer recording layer and the white hiding layer. .

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The principle of transfer of a thermal transfer recording medium of the present invention is that heat is applied to a thermal transfer recording material by a thermal medium such as a thermal head, and the heat causes an epoxy resin which is a heat-melting substance in a thermal transfer recording layer. Becomes a dissolved state, the tackiness is developed, and an image is recorded by thermally adhering onto the intermediate transfer foil. Therefore, when printing is performed by overlapping at least two colors, a clear print without ink bleeding can be obtained. Also, the transferred recorded image has excellent mechanical strength. Further, the thermal transfer recording layer is formed by repeatedly coating at least three colors of cyan, magenta, and yellow in a frame-sequential manner along the longitudinal direction of the support, and by transferring the thermal transfer recording layer of each color sequentially, a full-color image can be obtained. An image can be formed, and by providing a white concealing layer on the image portion, a transfer target colored other than white, a transfer target having gloss such as metal or metal vapor deposition, or glass or transparent plastic It is possible to arbitrarily transfer a full-color image onto such a transparent transfer body.

Further, by selecting the resin in the thermal transfer recording layer and the white hiding layer, retransfer is possible without pretreatment such as primer application even if the surface of the transferred material is metal or glass.

The thermal transfer recording medium of the present invention will be described in detail below. 1 and 2, a thermal transfer recording layer (3), a white hiding layer (4), and a transparent adhesive layer (5) on a support (2).
1 shows a thermal transfer recording medium (1) according to the present invention provided with.

Support (2) that can be used in the present invention
As the material, those generally used for sublimation transfer type and melt transfer type can be used. Specifically, plastic films such as polyethylene terephthalate, polyethylene naphthalate, polypropylene, cellophane, polycarbonate, polyvinyl chloride, polystyrene, polyimide, nylon, polyvinylidene chloride,
Papers such as condenser paper and paraffin paper can be mentioned, but polyester film is particularly preferable. The thickness of the support (2) is 2 to 50 μm, more preferably 2 to 16 μm. The thermal transfer recording layer (3) is
The coloring pigment and the resin are composed of colorless or light-colored fine particles, and the white hiding layer (4) is composed of the white pigment and the resin.

The composition of the composition for forming the thermal transfer recording layer (3) is such that the total solid content is 100 parts by weight.
The coloring pigment is 19 to 30 parts by weight, the resin is 40 to 80 parts by weight, and the colorless or light-colored fine particles are 1 to 30 parts by weight. When the amount of the coloring pigment is less than the above range, the desired printing density cannot be obtained, and when the amount is more than the above range, the film strength is lowered, which is not preferable. When the amount of the resin is less than the above range, it is not preferable because the film strength is lowered, and when the amount of the resin is more than the above range, the transferability, more specifically, the dot shape on which a transferred image is formed, the gradation reproducibility and the like are deteriorated. When the amount of colorless fine particles is less than the above range, it is not preferable because the transferability, more specifically, the dot shape on which a transferred image is formed and gradation reproducibility are deteriorated. When the amount is large, good ink fluidity is obtained. Absent.
In addition, various additives can be added to this, if necessary. The addition amount is preferably 10 parts by weight or less with respect to 100 parts by weight of the composition for forming the thermal transfer recording layer.

The thickness of the thermal transfer recording layer (3) is 0.2.
˜1.0 μm is desirable. If the film thickness is less than 0.2 μm, it is difficult to obtain a sufficient density, and if it exceeds 1.0 μm, it becomes difficult to perform transfer according to the heat generation portion of the thermal head. The gradation reproducibility and the like are inferior.

Regarding the film thickness of each color of cyan, magenta, and yellow, since the dot shape and the gradation reproducibility are generally large depending on the thickness, it is general that the film thicknesses of the three colors are the same. In this case, the optical densities of the respective color components are often different, and a sufficient density may not be obtained for a particular color. In this case, since the dot shape and gradation reproducibility are less affected within the range of the above-mentioned film thickness, the thermal transfer recording layer of a specific color for which sufficient density cannot be obtained does not correspond to another specific thermal transfer recording. It is possible to make the film thickness thicker than the layer, and by doing so, a sufficient optical density can be obtained. This makes it possible to form a well-balanced high-density image of three colors without impairing the dot shape and gradation expression.

In contrast to the thermal transfer recording layer (3) as described above, the white hiding layer (4) does not need to reproduce gradation and only solid transfer to an arbitrary shape, and concealment and foil breakage are prioritized. It Therefore, the composition for forming the white hiding layer (4) is basically a white pigment and a resin, and the total solid content is 10
The white pigment is preferably 20 to 70 parts by weight and the resin is 30 to 80 parts by weight with respect to 0 part by weight. When the amount of the white pigment is less than the above range, the desired hiding property cannot be obtained, and when it is more than the above range, the film strength and the transfer sensitivity are deteriorated, which is not preferable. In addition, various additives can be added to this, if necessary. The addition amount is preferably 10 parts by weight or less with respect to 100 parts by weight of the composition for forming the thermal transfer recording layer.

The thickness of the white hiding layer (4) is preferably 0.5 to 2.0 μm. If the film thickness is less than 0.5 μm, it is difficult to provide sufficient concealing property, and 2.0
If it exceeds μm, it becomes difficult to perform transfer in accordance with the heat generation portion of the thermal head, and specifically, transfer sensitivity and foil breakage are deteriorated.

The resin used for the thermal transfer recording layer (3) and the white hiding layer (4) of the present invention includes the adhesive strength between the layers,
The same type of amorphous organic polymer is used in consideration of transfer sensitivity and the like. Among these amorphous organic polymers, in the present invention, by selecting the resin as shown below, dot reproducibility, good foil breakage, excellent gradation expression, and high color development image can be obtained. It is possible to obtain the thermal transfer recording layer (3) and the white hiding layer (4) which also have adhesiveness to glass or the like.

First, the resin has a softening point of 70 to 150 ° C. in the spherical method.
It is an epoxy resin in the range of. The thermal condition for thermal transfer using a thermal head is usually 300 to 40.
It is several milliseconds at 0 ° C., and when this is converted into a static condition, it becomes 5 seconds at 100 to 150 ° C. Further, as described above, in order to carry out thermal transfer recording, it is necessary to heat the resin until it softens or melts and becomes tacky. Therefore, considering the amount of heat supplied from the thermal head and the melting state of the epoxy resin, the upper limit of the spherical method softening point is 150 ° C. If a resin having an amount higher than this upper limit is used, more energy is required for transfer, and the life of the thermal head becomes extremely short. Further, if an epoxy resin having a softening point of 70 ° C. or less is used, image peeling is likely to occur due to rubbing or cellophane tape peeling after retransfer, and also when the thermal transfer recording medium is stored, it is not rolled up. Blocking is likely to occur during storage.

As a characteristic of the epoxy resin used as a main material in the thermal transfer recording layer of the present invention, particularly preferably, the epoxy equivalent (the number of grams of resin containing 1 gram of epoxy group) is 600 to 5,000, and the molecular weight is Is 800
~ 5000. If the epoxy equivalent of this epoxy resin is lower than the lower limit value (less than 600), the durability of the image against rubbing is not sufficient and peeling of the image part occurs due to rubbing or cellophane tape peeling even after retransfer. It is not preferable because it is easy to do. On the contrary, if the epoxy equivalent is higher than the upper limit value (5,000
Since the thermal energy required for thermal transfer is too large, the life of the thermal head is shortened, and the sensitivity of thermal transfer is low. It is unsuitable for use as it is not preferable.

Then, the molecular weight of this epoxy resin is
If it is lower than the lower limit value (less than 800), the durability of the image against rubbing is not sufficient, and peeling is likely to occur in the transferred image due to rubbing after retransfer, which is not preferable. On the other hand, if the molecular weight is higher than the upper limit (greater than 5,000), the thermal energy required for thermal transfer is too large, which shortens the life of the thermal head. However, the sensitivity of the heat-sensitive transfer is low, and it is not suitable for the purpose of the heat-sensitive transfer recording of an image at a high speed, which is not preferable.

The most preferable epoxy resin in the present invention is a case where all the characteristics of the spheroidal softening point, the epoxy equivalent and the molecular weight are simultaneously within the respective ranges. In this case, a high effect can be obtained particularly in terms of image transferability and durability, which is preferable.

For the above reason, the softening point by the spherical method is 70-15.
An epoxy resin having an epoxy equivalent of 600 to 5000 and a molecular weight of 800 to 5000 is selected at 0 ° C., and examples of such an epoxy resin include bisphenol A diglycidyl ether and bisphenol F diglycidyl ether. Ether, resorcinol diglycidyl ether, cresol novolac polyglycidyl ether, tetrabromobisphenol A diglycidyl ether, glycidyl ether type epoxy resin such as bisphenol hexafluoroacetone glycidyl ether, phthalic acid diglycidyl ester, dimer acid diglycidyl ester and other glycidyl ester Type epoxy resin,
Glycidyl amine type epoxy resins such as triglycidyl isocyanurate, tetraglycidyl aminodiphenylmethane, and tetraglycidyl metaximendiamine, and hexahydrobisphenol A diglycidyl ether,
Examples thereof include aliphatic epoxy resins such as polypropylene glycol diglycidyl ether and neopentyl glycol diglycidyl ether.

Next, the glass transition point (Tg) is 40 to 10
It is an acrylic resin in the range of 0 ° C. The acrylic resin contained in the thermal transfer recording layer (3) and the white hiding layer (4) of the present invention also has a Tg in consideration of printability on a thermal medium such as a thermal head and durability of an image after transfer recording.
Is in the range of 40 ° C to 100 ° C. When the Tg of the acrylic resin is 100 ° C. or higher when performing thermal transfer using a thermal head, the energy applied to the thermal head for thermal transfer becomes too large, which shortens the life of the thermal head and also uses a sublimation transfer method. The energy advantage is lost compared to. Further, when Tg is 40 ° C. or less, peeling of an image easily occurs due to rubbing or peeling of cellophane tape after retransfer.
In addition, when the thermal transfer recording medium is stored, blocking or the like is likely to occur when the wound state is stored.

The acrylic resin used as a main material in the thermal transfer recording layer of the present invention preferably has a weight average molecular weight of 2,000 to 50,000. If the weight average molecular weight of the acrylic resin is lower than the lower limit value (less than 2000), the durability of the image against rubbing is not sufficient, and the transferred image after retransfer is peeled off by rubbing or cellophane tape peeling. Is likely to occur, which is not preferable. On the other hand, if the weight average molecular weight is higher than the upper limit (greater than 50,000), the transferability is deteriorated and the resolution of the obtained image is deteriorated because the foil transfer of the thermal transfer recording layer is deteriorated. turn into.

As the acrylic resin used in the present invention, for example, those contained in the above Tg and molecular weight ranges can be appropriately selected and used from the following acrylic resins. For example, acrylic acid, methacrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate,
Propyl (meth) acrylate, isopropyl (meth) acrylate, amyl (meth) acrylate, butyl (meth) acrylate, octyl (meth) acrylate, stearyl (meth) acrylate, decyl (meth) acrylate, ( Homopolymers of acrylic monomers such as (meth) acrylonitrile, copolymers thereof, and other monomers copolymerizable with one or more of the above acrylic monomers,
Examples thereof include copolymers with styrene, butadiene and the like.

Another is that the average molecular weight is 10,000 to 20.
It is a vinyl chloride vinyl acetate copolymer resin in the range of 000. The vinyl chloride vinyl acetate copolymer resin contained in the thermal transfer recording layer (3) and the white hiding layer (4) of the present invention similarly improves the printability on a heat medium such as a thermal head and the durability of the image after transfer recording. Considering this, those having an average molecular weight in the range of 10,000 to 20,000 are used.
When thermal transfer is performed using a thermal head, the vinyl chloride / vinyl acetate copolymer resin has an average molecular weight of 20,000.
When it is above, the film strength is strong and the cutting is poor, and the dot reproducibility and gradation are deteriorated. Further, the transfer sensitivity also deteriorates, and the energy applied to the thermal head for thermal transfer becomes too large, which shortens the life of the thermal head and loses the energy superiority as compared with the sublimation transfer method. When the average molecular weight is 10,000 or less, peeling of the transferred image is likely to occur due to rubbing after retransfer or peeling of cellophane tape.

The vinyl chloride-vinyl acetate copolymer resin used as a main material in the thermal transfer recording layer of the present invention preferably has a Tg of 60 to 80 ° C. Tg is 80 ° C
With the above vinyl chloride / vinyl acetate copolymer resin, the transfer sensitivity also deteriorates and the applied energy to the thermal head for thermal transfer becomes too large, which shortens the life of the thermal head and has an energy advantage compared to the sublimation transfer method. The nature disappears. Further, if the Tg is 60 ° C. or less, peeling of an image is likely to occur due to rubbing or cellophane tape peeling after retransfer, and blocking also occurs during storage of the thermal transfer recording medium during storage of the wound state. It will be easier.

As the vinyl chloride vinyl acetate copolymer resin used in the present invention, for example, among the vinyl chloride vinyl acetate copolymer resins exemplified below, those which fall within the molecular weight and Tg range can be appropriately selected and used. Can be done. For example, in addition to the usual vinyl chloride vinyl acetate copolymer resin, vinyl chloride vinyl acetate vinyl alcohol copolymer resin, vinyl chloride vinyl acetate maleic acid copolymer resin, vinyl chloride vinyl acetate acrylic acid copolymer resin, vinyl chloride vinyl acetate hydroxy acrylate. Examples thereof include copolymer resins, vinyl chloride vinyl acetate vinyl alcohol maleic acid copolymer resins, and the like.

The colorless or light-colored fine particles contained in the thermal transfer recording layer (3) are used in order to improve transferability at the time of thermal transfer, more specifically, dot shape on which a transferred image is formed, and gradation reproducibility. The colorless or light-colored components that are necessary components are used so as not to impair the coloring of the colored image formed by thermal transfer. Examples of such colorless or light-colored fine particles include silica, calcium carbonate, kaolin, clay, starch, zinc oxide, Teflon (registered trademark).
Examples thereof include powder, polyethylene powder, polymethylmethacrylate resin beads, polyurethane resin beads, benzoguanamine and melamine resin beads. Among the above, silica fine particles are particularly preferable, and silica having an average particle diameter of 0.1 μm or less is particularly preferable.

As the color pigment contained in the thermal transfer recording layer (3), various known pigments can be used. As an example, carbon black is preferable for black single color printing, and for multicolor printing, pigments forming yellow, magenta, and cyan and four color pigments obtained by adding black to these three color pigments are used. These pigments can be used alone or in combination of two or more.

As the white pigment contained in the white hiding layer, various known pigments can be used. As an example,
Examples thereof include calcium carbonate, titanium oxide, talc, kaolin, clay, titanium oxide, aluminum hydroxide, satin white, polyethylene powder, polymethylmethacrylate resin beads, polyurethane resin beads, benzoguanamine and melamine resin beads.
It is also possible to use one kind or a combination of two or more kinds. Among these white pigments, a pigment having a good hiding property is preferably used, and more preferably a white pigment having an average particle size of 0.1 μm to 1 μm is preferably used.

In the thermal transfer recording medium (1) of the present invention, a transparent adhesive layer (5) can be provided on the support (2) in addition to the thermal transfer recording layer (3) and the white hiding layer (4). By providing the adhesive layer (5), the thermal transfer recording layer (3) of each color is sequentially transferred onto the image receiving layer on the intermediate transfer foil to form an image, and then the white hiding layer (4) is transferred to further form the adhesive layer ( 5) is transferred and then retransferred to the transfer target. Since the adhesive layer (5) is transferred to the entire surface in an area to be retransferred or a larger area, dot reproduction and gradation are not necessary, and the image receiving layer, the thermal transfer recording layer (3) and the white hiding layer (4) are not necessary. It is possible to use a resin that has better adhesiveness to the transferred material. As a result, a stronger transfer image can be obtained with respect to the transferred material which is weakly adhered to the image receiving layer, the thermal transfer recording layer (3) and the white hiding layer (4).

As the resin used in the adhesive layer of the present invention, an amorphous organic polymer of the same type as the resin used in the thermal transfer recording layer or the white hiding layer is selected, and a resin having good adhesiveness to the transferred material is selected. Can be added. For example, epoxy resins, acrylic resins, vinyl chloride-vinyl acetate copolymer resins, as well as thermoplastic resins nitrocellulose, ethyl cellulose, cellulose derivatives such as cellulose acetate propionate, polystyrene, styrene resins such as poly α-methylstyrene, Vinyl resins such as polyvinyl chloride, polyvinyl acetate, polyvinyl butyral, polyvinyl acetal, polyester resins, polyamide resins, polyurethane resins, petroleum resins, ionomers, ethylene acrylic acid copolymers,
Synthetic resin such as ethylene-acrylic acid ester copolymer,
One or more heats of natural resin such as rosin, rosin-modified maleic acid resin, ester gum, polyisobutylene rubber, butyl rubber, styrene butadiene rubber, butadiene acrylonitrile rubber, polyamide resin, polychlorinated olefins or derivatives of synthetic rubber. For example, a plastic resin. The thickness of the adhesive layer is preferably 0.1 to 5 μm. Further, in addition to the resin, various fillers such as silicone oil, silicone powder and silica may be added without any problem.

In the thermal transfer recording medium of the present invention, by transferring the white hiding layer to any position, a normal full-color image can be transferred to the part to which the white hiding layer is transferred, and to the part where the white hiding layer is not transferred. It is possible to obtain a metallic image for a transfer target having a metallic luster and a transparent image for a transparent transfer target.

In the method for producing a thermal transfer recording medium of the present invention, a composition obtained by dispersing or dissolving the material of each layer on a substrate such as plastic in water or an organic solvent is subjected to surface coating by a solvent coating method such as gravure coating. The thermal transfer recording layer is formed by sequentially coating and drying.

Further, the thermal transfer recording layer (3) of the support (2)
When the heat transfer recording layer (3) is transferred onto the intermediate transfer foil by applying heat from the side not provided with the heat transfer head, the thermal head adheres to the support (2) and the heat transfer recording medium (1) In order to prevent the smooth running property of (1) from being disturbed, it is desirable to provide a back coat layer (6) on the side of the support (2) where the thermal transfer recording layer (3) is not provided.

Examples of the material used for the back coat layer (6) include nitrocellulose, polyester resin, acrylic resin, vinyl resin and the like containing silicone oil, or silicone modified resin. it can. Further, a crosslinking agent may be used in combination for the purpose of improving heat resistance. The coating thickness when the back coat layer (6) is provided is preferably about 0.1 to 2 μm.

The intermediate transfer foil used to form an image using the thermal transfer recording medium (1) as described above is
Papers such as high-quality papers and coated papers, plastic films such as polyester films, polyvinyl chloride films and polypropylene films, or papers and plastic films coated with an image receiving layer may be mentioned.

The image-receiving layer used here is preferably an amorphous organic polymer of the same kind as that commonly used for the thermal transfer recording layer, the white hiding layer and the adhesive layer of the thermal transfer recording medium. That is, by using the same kind of resin as the image receiving layer, even if the thermal transfer recording layer of the thermal transfer recording medium is not sufficiently melted during thermal transfer, the thermal transfer recording layer and the image receiving layer are well adhered by the heat during thermal transfer, Since printing is performed with sufficient foil breakage, transferability, more specifically, dot shape on which a transferred image is formed, gradation reproducibility, and the like are improved. Further, the formed image has excellent image resistance such as abrasion resistance and scratch resistance. Further, a peeling layer for controlling the peeling force, a protective layer for improving the resistance after retransfer, a hologram layer for providing security, etc. may be optionally provided between the support and the image receiving layer. Good.

As the means for applying thermal energy used when obtaining a gradation image expression by area gradation using the thermal transfer recording medium of the present invention as described above and the intermediate transfer foil as described above, conventionally known applying means can be used. Any of these can be used, and a gradation image can be obtained by controlling the thermal energy.

[0051]

EXAMPLES Next, the present invention will be described more specifically with reference to examples. In addition, unless otherwise specified, “parts” and “%” in the text are based on weight. (Example 1) First, an ink composition for a thermal transfer recording layer having the following composition was prepared. (Cyan ink) Phthalocyanine blue: 9 parts Epoxy resin (Okaka Shell Epoxy Co., Ltd .: Epicoat 1007): 20 parts * Softening point 128 ° C. Epoxy equivalent 1750 to 2200 Molecular weight 2900 Colorless fine particles (silica: Aerosil of Nippon Aerosil Co., Ltd.) R972) 4 parts Methyl ethyl ketone 67 parts (magenta ink) Carmine 6B 9 parts Epoxy resin (Okaka Shell Epoxy Co., Ltd .: Epicoat 1007) 20 parts * Softening point 128 ° C. Epoxy equivalent 1750-2200 Molecular weight 2900 colorless particles ( Silica: Aerosil R972 manufactured by Nippon Aerosil Co., Ltd. 4 parts Methyl ethyl ketone 67 parts (Yellow ink) Disazo yellow 9 parts Epoxy resin (Yukaka Shell Epoxy Co., Ltd .: Epicoat 1007) 20 parts * Softening point 128 ° C Epoxy equivalent 1750 to 2200 Molecular weight 2900 Colorless fine particles (silica: Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) 4 parts Methyl ethyl ketone 67 parts (white hiding layer ink) Titanium oxide 10 parts Epoxy resin (Oilized Shell Epoxy Co., Ltd.): Epicoat 1007) 20 parts * Softening point 128 ° C Epoxy equivalent 1750 to 2200 Molecular weight 2900 Methyl ethyl ketone 70 parts

A thermal transfer recording layer ink of the above formulation was applied to a polyethylene terephthalate film having a thickness of 5.4 μm, which was heat-treated on the back surface, and a dry film thickness of cyan, magenta and yellow was 0.6 μm using a gravure printing machine. The white concealing layer was repeatedly coated in a face-sequential manner in the longitudinal direction so as to have a thickness of 1.5 μm, coated and dried to obtain a thermal transfer recording medium of the present invention.

Then, the following image-receiving layer ink was applied to the easily adhesive surface of the 100 μm easily adhesive polyester film so as to have a dry film thickness of 5 μm and dried to obtain an intermediate transfer foil. (Image-receiving layer ink) Epoxy resin (Okaka Shell Epoxy Co., Ltd .: Epicoat 1007) 30 parts * Softening point 128 ° C Epoxy equivalent 1750 to 2200 Molecular weight 2900 Methyl ethyl ketone 70 parts

The surface of the thermal transfer recording layer of the obtained thermal transfer recording medium and the intermediate transfer foil are overlapped, and an image with area gradation corresponding to the heat generating portion of the thermal head is sequentially formed in the order of cyan, magenta and yellow by using a thermal head. It was possible to form a full-color image consisting only of area gradation on the intermediate transfer foil. Further, a white hiding layer is transferred onto the image, and is superposed on the transfer target (aluminum plate).
The image was transferred by pressing with a hot roll of 80 ° C.

Example 2 Using the thermal transfer recording layer of Example 1, the white hiding layer and the following adhesive layer, the same procedure as in Example 1 was carried out.
Using a gravure printing machine, a dry film thickness of cyan, magenta, and yellow is 0.6 for polyethylene terephthalate film with a thickness of 5.4 μm that is heat-treated on the back side of each ink.
.mu.m, the white hiding layer was 1.5 .mu.m, and the adhesive layer was 1.0 .mu.m. This was repeatedly applied separately in the surface direction along the longitudinal direction, coated and dried to obtain the thermal transfer recording medium of the present invention.

[0056] (Adhesive layer ink)   Epoxy resin (Okaka Shell Epoxy Co., Ltd .: Epicoat 1007) ... 20 parts       * Softening point 128 ° C Epoxy equivalent 1750-2200 Molecular weight 2900   Polyester resin (Toyobo Co., Ltd .: Byron 200)… 10 parts   Methyl ethyl ketone ... 70 parts

The obtained thermal transfer recording medium was subjected to the same procedure as in Example 1 to form a full-color image consisting of only area gradations on the intermediate transfer foil, and the white hiding layer was transferred onto the image to further transfer the adhesive layer. The image was transferred from the back surface of the intermediate transfer foil by applying pressure with a heat roll of 180 ° C. on the transfer body (aluminum plate).

The thermal transfer recording medium and the intermediate transfer foil were prepared in the same manner as in Examples 1 and 2 by changing the type and ratio of the resin as shown in the table below, and the image was transferred to the intermediate transfer foil to transfer the material (aluminum plate). Was retransferred to.

[0059]

[Table 1]

In this table, the composition is expressed in parts by weight and the coating amount is expressed in μm as the layer thickness.

The softening point, glass transition point and molecular weight of the resin used are shown in the following table.

[0062]

[Table 2]

With respect to the transferred material having the above-described structure, the image quality and resistance were evaluated. The evaluation results are as follows.

[0064]

[Table 3]

As shown in the above table, in the thermal transfer recording media (Examples 1 to 6) according to the present invention, the full color image produced with gradation reproducibility was faithfully reproduced from the highlight part to the shadow part and further at high density. It was possible to obtain an excellent thermal transfer recording medium having the durability of the image after recording, and the object of the present invention was achieved.

[0066]

INDUSTRIAL APPLICABILITY According to the present invention, a thermal transfer recording layer contains a color pigment, a binder resin and colorless fine particles, and the thermal transfer recording layer is thermally transferred onto an intermediate transfer foil from which the image receiving layer can be peeled by a thermal head printer. An image with excellent gradation reproducibility due to area gradation can be formed, a white hiding layer can be arbitrarily transferred onto the image, and a transparent adhesive layer can be further transferred. The image receiving layer on which this image was formed can be transferred. Provided is a thermal transfer recording medium that can be retransferred to the body by heat, and can transfer an arbitrary full-color image, particularly to metal or glass, and is excellent in image storability and mechanical strength after transfer. be able to.

[Brief description of drawings]

1A and 1B illustrate an embodiment of a thermal transfer sheet (thermal transfer recording medium) of the present invention, in which (A) is a plan view and (B) is a plan view.
FIG. 3 is a sectional view of the configuration.

FIG. 2 is a view for explaining another embodiment of the thermal transfer sheet (thermal transfer recording medium) of the present invention, (A) is a plan view,
(B) is a configuration cross-sectional view.

[Explanation of symbols]

1 ... Thermal transfer recording medium 2 ... Support 3 ... Thermal transfer recording layer 4 ... White hiding layer 5 ... Adhesive layer 6 ... Back coat layer

Continued front page    F term (reference) 2C068 AA06 BC13 BC34 BD15 BD23                 2H111 AA05 AA26 AA33 AB05 BA03                       BA08 BA14 BA32 BA35 BA38                       BA47 BA48 BA49 BA53 BA71                       BA78 BB06

Claims (7)

[Claims] 1. A thermal transfer recording medium having a thermal transfer recording layer which is melted or softened by heat and transferred to at least one of the substrates, and is preliminarily printed on an intermediate transfer medium having at least a transferable image receiving layer, and the image is printed. In a thermal transfer recording medium used in a thermal transfer recording method for transferring an image receiving layer of an intermediate transfer medium to a target transfer body, a thermal transfer recording layer mainly composed of colorless or light-colored fine particles, a coloring pigment, and a resin is used as a support. A thermal transfer recording medium in which at least three colors of cyan, magenta, and yellow and a white concealing layer are separately coated along the longitudinal direction in a frame-sequential manner, and the composition forming the thermal transfer recording layer of each color is The coloring pigment is 19 to 30 parts by weight, the resin is 40 to 80 parts by weight, and the colorless or light-colored fine particles are 1 to 30 parts by weight based on 100 parts by weight of the total solid content. A thermal transfer recording medium having a composite composition and a film thickness of 0.2 to 1.0 μm, wherein the resins of the thermal transfer recording layer of each color and the white hiding layer are amorphous organic polymers of the same kind. 2. A thermal transfer recording layer comprising at least three colors of cyan, magenta, and yellow, a white hiding layer, and a transparent adhesive layer, which are separately coated in a frame-sequential manner along the longitudinal direction of the support. The thermal transfer recording medium according to claim 1. 3. The thermal transfer according to claim 1, wherein the resin in the thermal transfer recording layer and the white hiding layer is an epoxy resin having a spherical softening point in the range of 70 to 150 ° C. recoding media. 4. The thermal transfer recording according to claim 1, wherein the resin in the thermal transfer recording layer and the white hiding layer is an acrylic resin having a glass transition point in the range of 40 to 100 ° C. Medium. 5. The resin in the thermal transfer recording layer and the white hiding layer is a vinyl chloride / vinyl acetate copolymer resin having an average molecular weight in the range of 10,000 to 20,000. A thermal transfer recording medium according to any one of 1. 6. The thermal transfer recording medium according to claim 1, wherein the colorless or light-colored fine particles in the thermal transfer recording layer are silica. 7. The thermal transfer recording medium according to claim 1, wherein the transparent adhesive layer contains the same resin as the resin in the thermal transfer recording layer and the white hiding layer.