JP4415514B2 - Thermal transfer recording medium and thermal transfer recording method using the same - Google Patents

Description

【００６０】
この表において、組成は重量部を、塗布量は層厚をμｍで表している。
【００６１】
また、使用した樹脂の球状法軟化点、ガラス転移点、分子量を次表に示す。
【００６２】
【表２】

【００６３】
以上のよう構成で得られた被転写物について画質および耐性等の評価を行った。評価結果は次の通りである。
【００６４】
【表３】

【００６５】
上記の表に示した通り本発明による熱転写記録媒体（実施例１〜６）は、階調再現性において作製したフルカラー画像がハイライト部からシャドウ部まで忠実に再現され高濃度で更に、記録後の画像の耐久性を具備した優れた熱転写記録媒体を得ることができ、本発明の目的が達成された。
【００６６】
【発明の効果】
本発明は、熱転写記録層中に着色顔料とバインダー樹脂と無色の微粒子とを含有させ、サーマルヘッドプリンタで熱転写記録層を受像層が剥離可能な中間転写箔上に熱転写し、面積階調による階調再現性の優れた画像を形成し、その画像上に白色隠蔽層を任意に転写し、更に透明接着層を転写することができ、この画像を形成した受像層を被転写体へ熱による再転写ができる熱転写記録媒体であって、特に金属やガラス等に任意のフルカラー画像が転写でき、転写後の画像の保存性、機械的強度に優れている熱転写記録媒体を提供することができる。
【図面の簡単な説明】
【図１】本発明の熱転写シート（熱転写記録媒体）の一実施例を説明するものであり、（Ａ）は平面図、（Ｂ）は構成断面図である。
【図２】本発明の熱転写シート（熱転写記録媒体）の別の一実施例を説明するものであり、（Ａ）は平面図、（Ｂ）は構成断面図である。
【符号の説明】
１…熱転写記録媒体
２…支持体
３…熱転写記録層
４…白色隠蔽層
５…接着層
６…バックコート層[0001]
BACKGROUND OF THE INVENTION
The present invention thermally transfers a thermal transfer recording layer containing a color pigment with a thermal head printer onto an intermediate transfer foil having a transferable image receiving layer. It is a thermal transfer recording medium for forming a color image and transferring the image receiving layer of the printed intermediate transfer medium to a target transfer target, and can be transferred particularly well to articles such as metal and glass. The present invention relates to a thermal transfer recording medium.
[0002]
[Prior art]
Conventionally, a sublimation transfer method and a melt transfer method are known as thermal transfer recording methods for forming a gradation image using a thermal head printer.
[0003]
In the sublimation transfer method, a thermal transfer recording layer provided on a support with a thermal transfer recording layer comprising a sublimation (heat transferable) dye and a binder resin is overlapped with an image receiving sheet, and the thermal transfer recording layer in the thermal transfer recording layer depends on the amount of heat of the thermal head. A gradation image is formed by transferring a sublimation dye onto an image receiving sheet.
However, when an image is formed using such a sublimation (heat transferable) dye, the formed image is inferior in durability, and 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 system, it is not suitable as a high-speed recording material that uses a high-resolution thermal head that is expected to be used in the future. have.
[0004]
On the other hand, the melt transfer method uses a thermal transfer recording medium in which a heat-meltable ink transfer layer comprising a colorant such as pigment or dye and a binder such as wax is provided on a support, and an image is applied to a heating device such as a thermal head. In this method, energy is applied according to information, and an ink transfer layer is fused on an image receiving sheet to form an image. An 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. In addition, it is possible to form a color image by using a thermal transfer recording medium made of yellow, magenta, cyan, and black to form an image superimposed on an image receiving sheet. Japanese Patent Publication No. 63-65029 discloses such a thermal transfer recording medium for color image formation.
On the other hand, in the thermal transfer recording method, the image is not directly transferred to the image receiving sheet to be transferred as described above to obtain a final transfer product, but also peeled off without directly transferring the image from the thermal transfer recording medium to the target transfer target. There is a method in which an image composed of a thermal transfer recording layer is transferred onto an image receiving layer of an intermediate medium provided with a possible image receiving layer, and then the image (thermal transfer recording layer) is retransferred together with the image receiving layer to a target transfer target. Are known. Hereinafter, this is referred to as a retransfer method.
[0005]
Using this method, images can be transferred to various objects such as cash cards, credit cards, various ID cards, prepaid cards, plastic cards such as government postcards and passports, cloths such as T-shirts and handkerchiefs. It becomes possible.
In this method, it is possible to obtain a high-resolution image regardless of the material and surface state of the transferred material compared to the method for directly printing on the intended transferred material, and printing on a non-smooth transferred material is possible. There are advantages such as being possible.
However, depending on the transfer target, when the intermediate transfer medium to which the image is finally transferred is transferred to the target transfer target, the adhesion with the image receiving layer of the intermediate transfer medium and the printed thermal transfer ink layer is improved. It is necessary to provide a primer layer by applying primer layer ink to the surface of the transfer medium in advance. In many cases, such a pretreatment for a transfer medium is very time-consuming, and depending on the transfer medium, the pretreatment may not be possible.
[0006]
In addition to conventional plastic plates such as prepaid cards, cash cards, credit cards, and various ID cards, thermal transfer recording media that can be used for transfer materials of various materials such as metal plates and glass plates have been developed so far. There was no.
[0007]
[Problems to be solved by the invention]
In the case of the thermal transfer recording medium described in the above Japanese Patent Publication No. 63-65029, the low melting point crystalline wax is used as a binder for the ink layer, so that the resolution tends to decrease due to ink bleeding. Further, the adhesive strength and film strength of the transferred image are weak, and if the image portion is rubbed with hand, the image portion is removed. Various proposals have been made as methods for solving such a phenomenon. For example, JP-A-61-244592 proposes a thermal transfer recording medium having a thermal ink layer composed of 65% or more of an amorphous polymer, a releasable substance and a colorant.
However, since the thermal transfer recording medium described in JP-A-61-244592 also contains a crystalline wax, the adhesive strength of the portion where each color is overprinted is insufficient.
[0008]
These low adhesive strengths are covered to some extent because the transferred image receiving layer serves as a protective layer in the retransfer method, and the transferred image receiving layer is covered to some extent. It will come off. Further, no matter how strong the adhesive strength and the film strength of the ink layer and the image receiving layer as a transfer image are, the adhesive layer is peeled off from the transferred material unless the adhesive strength with the transferred material is strong. For this reason, it has been necessary to preliminarily apply a primer layer as a pretreatment to the transfer object, thereby strengthening the adhesive strength between the transfer object, the transferred image, and the image receiving layer.
[0009]
In addition, any full-color image can be printed on a transfer object colored other than white, a glossy transfer object such as a metal or a metal deposit, or a transparent transfer object such as glass or transparent plastic. When transferring, it is necessary to apply a white layer only to the part to which the image is transferred as pre-processing, but it is very difficult, and a full color image is provided at any position other than the white part, or it is transparent or metallic. A tone image could not be provided at an arbitrary position.
[0010]
The present invention has been made in view of the above-mentioned problems of the prior art, and prevents a decrease in resolving power due to ink bleeding caused by using a low-melting crystalline wax as a binder for the ink layer. In addition, if wax is used, the transferred image will not be durable enough to be rubbed by hand, improving the point that the image is likely to be lost and increasing the durability, and at the same time sufficiently achieving these The purpose is to provide a thermal transfer recording medium capable of printing, and in particular, there is no pretreatment such as primer application on a transparent or metallic glossy transfer material made of glass or metal in addition to paper or plastic card. It is an object of the present invention to provide a thermal transfer recording medium capable of forming an arbitrary image.
[0011]
[Means for Solving the Problems]
  As a result of intensive studies, the present inventors have made it possible to solve the above problems by using a melt transfer method.
  That is, the invention according to item 1 is a thermal transfer recording medium having a thermal transfer recording layer that is transferred by melting or softening by heat to at least one of the substrates.Because
  A thermal transfer recording layer mainly composed of colorless or light-colored fine particles, a color pigment, and a resin, and at least three colors of cyan, magenta, and yellow and a white hiding layer along the longitudinal direction of the supportAnd transparent adhesive layerAre repeatedly applied in the surface order.RThe composition forming the thermal transfer recording layer of each color is 19 to 30 parts by weight of the color pigment, 40 to 80 parts by weight of the resin, and 1 to 30 of colorless or light-colored fine particles with respect to 100 parts by weight of the total solid content. The blending composition of parts by weight has a film thickness of 0.2 to 1.0 μm, and the thermal transfer recording layer and the white hiding layer of each color are the same kind of amorphous organic polymer.The composition forming the white hiding layer is 20 to 70 parts by weight of white pigment and 30 to 80 parts by weight of resin with respect to 100 parts by weight of the total solid content.This is a thermal transfer recording medium.
[0012]
  The invention according to claim 22. The thermal transfer recording medium 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. 3.It is.
[0013]
  The invention according to claim 3 is:2. The thermal transfer recording medium 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 of 40 to 100 ° C. 3.It is.
[0014]
  The invention according to claim 4 is:2. The thermal transfer recording medium according to claim 1, wherein 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.It is.
[0015]
  The invention according to claim 5 is:5. 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.It is.
[0016]
  The invention according to claim 6 is:6. The thermal transfer recording medium according to claim 1, wherein the transparent adhesive layer contains the same type of resin as that in the thermal transfer recording layer and the white hiding layer..
[0017]
  The invention according to claim 7 is:Using the thermal transfer recording medium according to claim 1, printing is performed in advance on an intermediate transfer medium having at least a transferable image receiving layer, and the image receiving layer of the printed intermediate transfer medium is transferred to a target transfer medium. Thermal transfer recording method characterized in thatIt is.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
The transfer principle of the thermal transfer recording medium of the present invention is that heat is applied to the thermal transfer recording material by a thermal medium such as a thermal head, and the epoxy resin, which is a heat-meltable substance in the thermal transfer recording layer, is dissolved by the heat and becomes sticky. The image is recorded by thermally adhering onto the intermediate transfer foil.
For this reason, when printing is performed with at least two or more colors superimposed, a clear print without ink bleeding is obtained. In addition, the transferred recorded image can obtain characteristics excellent in mechanical strength. Further, the thermal transfer recording layer is formed by repeatedly coating at least three colors of cyan, magenta, and yellow in the surface order along the longitudinal direction of the support. An image can be formed, and a transfer object colored other than white by providing a white concealing layer in the image part, a glossy transfer object such as metal or metal deposit, or glass or transparent plastic It is possible to arbitrarily transfer a full-color image onto a transparent transfer material as described above.
[0019]
Further, by selecting the resin in the thermal transfer recording layer and the white hiding layer, retransfer without pretreatment such as primer application is possible even if the surface of the transfer object is metal or glass.
[0020]
Hereinafter, the thermal transfer recording medium of the present invention will be described in detail.
1 and 2 show a thermal transfer recording medium (1) according to the present invention in which a thermal transfer recording layer (3), a white hiding layer (4), and a transparent adhesive layer (5) are provided on a support (2).
[0021]
As the support (2) that can be used in the present invention, those conventionally used for sublimation transfer molds and melt transfer molds can be used. Specific examples include polyethylene terephthalate, polyethylene naphthalate, polypropylene, cellophane, polycarbonate, polyvinyl chloride, polystyrene, polyimide, nylon, polyvinylidene chloride and other plastic films, condenser paper, paraffin paper and the like. However, a 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 made of a colored pigment, a resin, and colorless or light-colored fine particles, and the white hiding layer (4) is made of a white pigment and a resin.
[0022]
The composition of the composition for forming the thermal transfer recording layer (3) is 19 to 30 parts by weight of the color pigment, 40 to 80 parts by weight of the resin, colorless or light colored with respect to 100 parts by weight of the total solid content. The fine particles are 1 to 30 parts by weight.
When the color pigment is less than the above range, a desired printing density cannot be obtained, and when it is more, the film strength is not preferable.
When the amount of resin is less than the above range, it is not preferable because the film strength is lowered, and when it is large, the transfer property, specifically the dot shape on which the transferred image is formed, and the tone reproducibility are not preferable.
When the number of colorless fine particles is less than the above range, transferability, specifically, the dot shape on which a transferred image is formed, and gradation reproducibility are unfavorable, and when it is large, good ink fluidity is obtained. Absent.
Moreover, various additives can also be mix | blended with this as needed. 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.
[0023]
The film thickness of the thermal transfer recording layer (3) is preferably 0.2 to 1.0 μm.
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, transfer according to the heat generation part of the thermal head becomes difficult. The gradation reproducibility and the like are inferior.
[0024]
Regarding the film thickness of each color of cyan, magenta, and yellow, the dot shape and gradation reproducibility usually increase depending on the thickness, so that the film thicknesses of the three colors are generally the same. In this case, the optical density of each color component is often different, and a sufficient density may not be obtained for a specific color. In this case, the dot shape and gradation reproducibility are less affected as long as the film thickness is within the above-mentioned range. Therefore, for a specific color thermal transfer recording layer where a sufficient density cannot be obtained, other specific thermal transfer recording is performed. It is possible to make the film thickness thicker than the layer, and in this way, a sufficient optical density can be obtained. Thereby, it is possible to form a high-density image in which the three colors are balanced without impairing the dot shape and gradation expression.
[0025]
The white concealment layer (4) does not need to reproduce gradation and only performs solid transfer to an arbitrary shape with respect to the thermal transfer recording layer (3) as described above, but rather concealment and foil breakage are given priority. Therefore, the composition for forming the white hiding layer (4) is basically a white pigment and a resin, preferably 20 to 70 parts by weight of the white pigment and 30 to 30 parts by weight of the total solid content of 100 parts by weight. 80 parts by weight. When the white pigment is less than the above range, the desired hiding property cannot be obtained, and when it is more, the film strength and the transfer sensitivity are not preferable. Moreover, various additives can also be mix | blended with this as needed. 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.
[0026]
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 obtain sufficient concealment, and if it exceeds 2.0 μm, transfer according to the heat generation part of the thermal head becomes difficult, and in particular, transfer sensitivity and foil breakage are inferior. become.
[0027]
As the resin used for the thermal transfer recording layer (3) and the white hiding layer (4) of the present invention, the same kind of amorphous organic polymer is used in consideration of the adhesive strength between the layers, transfer sensitivity, and the like. Among these amorphous organic polymers, in the present invention, by selecting a resin as listed below, dot reproducibility, foil breakage is excellent, gradation expression is excellent, and a high color image is obtained. A thermal transfer recording layer (3) and a white hiding layer (4) having adhesion to glass and the like can also be obtained.
[0028]
First, the resin is an epoxy resin having a spherical softening point in the range of 70 to 150 ° C. The thermal conditions for thermal transfer using a thermal head are usually 300 to 400 ° C. for several milliseconds, and when converted to static conditions, the thermal condition is 100 to 150 ° C. for 5 seconds. Further, as described above, in order to perform thermal transfer recording, it is necessary to heat until the resin is softened or dissolved and has adhesiveness.
Therefore, the upper limit of the spherical method softening point is 150 ° C. in consideration of the amount of heat supplied from the thermal head and the dissolved state of the epoxy resin. If a resin exceeding this upper limit is used, more energy is required during transfer, and the life of the thermal head becomes extremely short. In addition, when an epoxy resin having a spherical softening point of 70 ° C. or less is used, the image is liable to be peeled off due to rubbing or cellophane tape peeling after re-transfer, and in the storage state of the thermal transfer recording medium. Blocking is likely to occur during storage.
[0029]
The epoxy resin used as the main material for the thermal transfer recording layer of the present invention is particularly preferably characterized by an epoxy equivalent (grams of resin containing 1 gram of epoxy groups) of 600 to 5000 and a molecular weight of 800 to 5000.
If the epoxy equivalent of this epoxy resin is lower than the above lower limit (less than 600), the image is not sufficiently durable against rubbing, and even after retransfer, peeling of the image area occurs due to rubbing or cellophane tape peeling. Since it is easy to do, it is not preferable. On the contrary, if this epoxy equivalent is higher than the upper limit (exceeding 5,000), the thermal energy required for thermal transfer is too much, and the life of the thermal head is shortened. In addition, since the sensitivity of thermal transfer is low, it is not suitable for applications in which an image is to be thermally transferred and recorded at high speed.
[0030]
Then, if the molecular weight of the epoxy resin is lower than the lower limit (less than 800), the durability of the image against rubbing is not sufficient, and the transferred image is easily peeled off by rubbing after retransfer. It is not preferable. Conversely, if this molecular weight is higher than the above upper limit (exceeding 5,000), the thermal energy required for thermal transfer will be too great, reducing the life of the thermal head. In addition, since the sensitivity of thermal transfer is low, it is not suitable for applications in which an image is to be thermally transferred and recorded at high speed.
[0031]
The most preferred epoxy resin in the present invention is the case where all the characteristics of the spherical method softening point, epoxy equivalent, and molecular weight are simultaneously within the respective ranges. In this case, a high effect can be obtained particularly with respect to the transferability and durability of the image.
[0032]
For these reasons, an epoxy resin having a spherical method softening point of 70 to 150 ° C., preferably an epoxy equivalent of 600 to 5000, and a molecular weight of 800 to 5000 is selected. Glycidyl ether type epoxy resins such as bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, resorcinol diglycidyl ether, cresol novolac polyglycidyl ether, tetrabromobisphenol A diglycidyl ether, bisphenol hexafluoroacetone glycidyl ether and diglycidyl phthalate Glycidyl ester type epoxy resin such as ester, dimer acid diglycidyl ester, triglycidyl isocyanurate, tetraglycidylaminodiphenylmethane, tetra Can be exemplified glycidyl meth alkoxy such as Men diamine glycidyl amine type epoxy resins, and hexa hydro bisphenol A diglycidyl ether, polypropylene glycol diglycidyl ether, aliphatic epoxy resins such as neopentyl glycol diglycidyl ether.
[0033]
Next, it is an acrylic resin whose glass transition point (Tg) exists in the range of 40-100 degreeC. Similarly, the acrylic resin contained in the thermal transfer recording layer (3) and the white concealing layer (4) of the present invention has a Tg of 40 in consideration of printing suitability to a thermal medium such as a thermal head and durability of an image after transfer recording. The thing of the range of 100 to 100 degreeC is used.
When thermal transfer is performed using a thermal head, if the Tg of the acrylic resin is 100 ° C. or higher, the energy applied to the thermal head for thermal transfer becomes too large, and the life of the thermal head is shortened. The energy advantage is lost. Also, if the Tg is 40 ° C. or lower, the image is liable to be peeled off due to rubbing or peeling of the cellophane tape after re-transfer, and blocking or the like occurs due to preservation of the winding state even when the thermal transfer recording medium is preserved. It becomes easy to do.
[0034]
The acrylic resin used as the main material for the thermal transfer recording layer of the present invention preferably has a weight average molecular weight of 2000 to 50000. If the weight average molecular weight of the acrylic resin is lower than the lower limit (less than 2000), the durability of the image against rubbing is not sufficient, and the transferred image after re-transfer is rubbed or peeled off by cellophane tape. Is not preferred because it is likely to occur. On the contrary, if the weight average molecular weight is higher than the upper limit (more than 50000), the transferability is deteriorated in order to deteriorate the foil breakage of the thermal transfer recording layer, and the resolution of the obtained image is deteriorated. turn into.
[0035]
As the acrylic resin used in the present invention, for example, those contained in the Tg and molecular weight ranges can be appropriately selected from the acrylic resins exemplified below. For example, acrylic acid, methacrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, amyl (meth) acrylate, butyl (meth) acrylate , Homopolymers of acrylic monomers such as octyl (meth) acrylate, stearyl (meth) acrylate, decyl (meth) acrylate, (meth) acrylonitrile, copolymers thereof, and the above acrylic Examples thereof include copolymers with other monomers that can be copolymerized with one or more monomers, such as styrene and butadiene.
[0036]
The other is a vinyl chloride vinyl acetate copolymer resin having an average molecular weight in the range of 10,000 to 20,000. The vinyl chloride vinyl acetate copolymer resin contained in the thermal transfer recording layer (3) and the white concealing layer (4) of the present invention similarly has the ability to print on a thermal medium such as a thermal head and the durability of the image after transfer recording. In consideration, the average molecular weight is in the range of 10,000 to 20,000.
When the thermal transfer is performed using a thermal head, if the average molecular weight of the vinyl chloride / vinyl acetate copolymer resin is 20,000 or more, the film strength is strong and the cut is poor and the dot reproducibility and gradation are deteriorated. In addition, the transfer sensitivity is deteriorated and the energy applied to the thermal head for thermal transfer becomes too large, shortening the life of the thermal head and losing the energy advantage compared with the sublimation transfer method. Further, if the average molecular weight is 10,000 or less, the transferred image is liable to be peeled off by rubbing after retransfer or cellophane tape peeling.
[0037]
The vinyl chloride vinyl acetate copolymer resin used as the main material for the thermal transfer recording layer of the present invention preferably has a Tg of 60 to 80 ° C. With vinyl chloride vinyl acetate copolymer resin with a Tg of 80 ° C or higher, the transfer sensitivity becomes poor and the energy applied to the thermal head for thermal transfer becomes too large, shortening the life of the thermal head and comparing with the sublimation transfer method. The energy advantage is lost. Also, if the Tg is 60 ° C. or lower, the image is likely to be peeled off due to rubbing or peeling of the cellophane tape after retransfer, and blocking or the like occurs when the wound state is stored even when the thermal transfer recording medium is stored. It becomes easy.
[0038]
As the vinyl chloride vinyl acetate copolymer resin used in the present invention, for example, among vinyl chloride vinyl acetate copolymer resins exemplified below, those included in the molecular weight and Tg ranges can be appropriately selected and used. 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 maleate copolymer resin, vinyl chloride vinyl acetate acrylic acid copolymer resin, vinyl chloride vinyl acetate hydroxyacrylate Examples thereof include copolymer resins and vinyl chloride vinyl acetate vinyl vinyl alcohol maleic acid copolymer resins.
[0039]
The colorless or light-colored fine particles contained in the thermal transfer recording layer (3) are components necessary for improving the transferability during thermal transfer, specifically the dot shape on which the transferred image is formed, and the gradation reproducibility. The reason why the colorless or light-colored one is used is so as not to impair the color development 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 powder, polyethylene powder, polymethyl methacrylate resin beads, polyurethane resin beads, benzoguanamine and melamine resin beads. Can be mentioned. Among the above, silica fine particles are particularly preferable, and silica having an average particle diameter of 0.1 μm or less is more preferable.
[0040]
Various known pigments can be used as the color pigment contained in the thermal transfer recording layer (3). As an example, carbon black is preferable for black monochromatic printing, and for multicolor printing, pigments that form 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.
[0041]
Various known pigments can be used as the white pigment contained in the white hiding layer. Examples include calcium carbonate, titanium oxide, talc, kaolin, clay, titanium oxide, aluminum hydroxide, satin white, polyethylene powder, polymethyl methacrylate resin beads, polyurethane resin beads, benzoguanamine, and melamine resin beads. . It is also possible to use one type or a combination of two or more types. Among these white pigments, pigments with good concealability are preferably used, and white pigments having an average particle diameter of 0.1 μm to 1 μm are more preferably used.
[0042]
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 this 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 and further the adhesive layer ( 5) is transferred, and then retransferred to the transfer target.
Since the adhesive layer (5) is transferred over the entire surface in a retransfer portion or larger area, dot reproduction and gradation are unnecessary, and an image receiving layer, a thermal transfer recording layer (3), a white hiding layer (4), Resins having better adhesion to the transfer target can be used. As a result, a stronger transfer image can be obtained with respect to the image receiving layer, the thermal transfer recording layer (3), the white hiding layer (4) and the transfer target having weak adhesion.
[0043]
As the resin used in the adhesive layer of the present invention, a resin having good adhesion to the transfer medium can be selected and added to the same type of amorphous organic polymer as that used in the thermal transfer recording layer and the white hiding layer.
For example, in addition to epoxy resins, acrylic resins, vinyl chloride vinyl acetate copolymer resins, thermoplastic resins such as nitrocellulose, ethyl cellulose, cellulose derivatives such as cellulose acetate propionate, polystyrene, styrene resins such as poly α-methylstyrene, Polyvinyl chloride, polyvinyl acetate, polyvinyl butyral, polyvinyl acetal and other vinyl resins, polyester resins, polyamide resins, polyurethane resins, petroleum resins, ionomers, ethylene acrylic acid copolymers, ethylene-acrylic acid ester copolymers, etc. Natural resins such as synthetic resins, rosin, rosin-modified maleic resin, ester gum, polyisobutylene rubber, butyl rubber, styrene butadiene rubber, butadiene acrylonitrile rubber, polyamide resin, polychlorinated olefin One or more thermoplastic resins of synthetic rubber derivatives, and the like.
The thickness of the adhesive layer is preferably 0.1 to 5 μm. In addition to the resin, various fillers such as silicone oil, silicone powder and silica may be added as appropriate.
[0044]
In the thermal transfer recording medium of the present invention, by transferring the white hiding layer to an arbitrary position, the portion where the white hiding layer is transferred can transfer a normal full color image, and the portion where the white hiding layer is not transferred has a metallic luster. A metallic-tone image can be obtained for the transferred object, and a transparent image can be obtained for the transparent object.
[0045]
The method for producing a thermal transfer recording medium of the present invention is a method in which a composition in which a material of each layer is dispersed or dissolved in water or an organic solvent on a substrate such as plastic is sequentially applied by a solvent coating method such as gravure coating. And drying to form a thermal transfer recording layer.
[0046]
Further, the thermal head is supported when transferring the thermal transfer recording layer (3) onto the intermediate transfer foil by applying heat using the thermal head from the side of the support (2) where the thermal transfer recording layer (3) is not provided. A back coat layer is provided on the side of the support (2) where the thermal transfer recording layer (3) is not provided in order to prevent it from adhering to the body (2) and hindering smooth running of the thermal transfer recording medium (1). It is desirable to provide (6).
[0047]
Examples of the material used for the back coat layer (6) include nitrocellulose, a polyester resin, an acrylic resin, a vinyl resin and the like containing silicon oil, or a silicon-modified resin. Moreover, you may use a crosslinking agent together in order to improve heat resistance.
The coating thickness when the back coat layer (6) is provided is preferably about 0.1 to 2 μm.
[0048]
As the intermediate transfer foil used to form an image using the thermal transfer recording medium (1) as described above, paper such as high-quality paper and coated paper, plastic such as polyester film, polyvinyl chloride film, and polypropylene film Examples thereof include a film, paper, or a plastic film coated with an image receiving layer.
[0049]
The image receiving layer used here is preferably an amorphous organic polymer of the same type as that used in common 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 type of resin as the image receiving layer, even if the thermal transfer recording layer of the thermal transfer recording medium is not sufficiently melted at the time of thermal transfer, the thermal transfer recording layer and the image receiving layer are well bonded by the heat at the time of thermal transfer, Since the image is printed with sufficient foil cutting, the transferability, specifically the dot shape on which the transfer image is formed, the gradation reproducibility, and the like are improved. Furthermore, the formed image has excellent image resistance such as abrasion resistance and scratch resistance. Further, a separation layer for controlling the separation force between the support and the image receiving layer, a protective layer for improving the resistance after retransfer, a hologram layer for providing security, etc. may be provided arbitrarily. Good.
[0050]
Conventionally known applying means are used as the means for applying thermal energy used for 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. The gradation image can be obtained by controlling the thermal energy.
[0051]
【Example】
Next, the present invention will be described more specifically with reference to examples. In the text, “%” or “%” is based on weight unless otherwise specified.
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 (Oilized Shell Epoxy Co., Ltd .: Epicoat 1007) ... 20 parts
* Softening point 128 ° C Epoxy equivalent 1750-2200 Molecular weight 2900
Colorless fine particles (silica: Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) 4 parts
Methyl ethyl ketone… 67 parts
(Magenta ink)
Carmin 6B ... 9 copies
Epoxy resin (Oilized Shell Epoxy Co., Ltd .: Epicoat 1007) ... 20 parts
* Softening point 128 ° C Epoxy equivalent 1750-2200 Molecular weight 2900
Colorless fine 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 (Oilized Shell Epoxy Co., Ltd .: Epicoat 1007) ... 20 parts
* Softening point 128 ° C Epoxy equivalent 1750-2200 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 1750-2200 Molecular weight 2900
Methyl ethyl ketone: 70 parts
[0052]
The thermal transfer recording layer ink of the above formulation is 5.4 μm thick polyethylene terephthalate film with heat-resistant treatment on the back surface, and a dry film thickness is 0.6 μm for cyan, magenta and yellow using a gravure printing machine, a white concealing layer Was repeatedly coated in the surface order along the longitudinal direction so as to be 1.5 μm, and coated and dried to obtain the thermal transfer recording medium of the present invention.
[0053]
Next, the intermediate transfer foil was obtained by applying and drying the easy-adhesion surface of the 100 μm easy-adhesive polyester film using the following image-receiving layer ink so that the dry film thickness was 5 μm.
(Image-receiving layer ink)
Epoxy resin (Oilized Shell Epoxy Co., Ltd .: Epicoat 1007) ... 30 parts
* Softening point 128 ° C Epoxy equivalent 1750-2200 Molecular weight 2900
Methyl ethyl ketone: 70 parts
[0054]
The thermal transfer recording layer surface of the obtained thermal transfer recording medium and the intermediate transfer foil are overlapped, and an image with an area gradation corresponding to the heat generating portion of the thermal head is sequentially formed in the order of cyan, magenta, and yellow using the thermal head, and intermediate transfer is performed. A full-color image consisting only of area gradations could be formed on the foil. Further, a white hiding layer was transferred onto the image, overlaid with the transfer target (aluminum plate), and pressed with a hot roll at 180 ° C. from the back surface of the intermediate transfer foil to transfer the image.
[0055]
(Example 2)
Using the thermal transfer recording layer, the white hiding layer and the following adhesive layer of Example 1, gravure printing was performed on a polyethylene terephthalate film having a thickness of 5.4 μm and heat-treated on the back surface of each ink as in Example 1. Using a coating machine, the dry film thickness is 0.6 μm for cyan, magenta, yellow, 1.5 μm for the white hiding layer, and 1.0 μm for the adhesive layer. Thus, the thermal transfer recording medium of the present invention was obtained.
[0056]
(Adhesive layer ink)
Epoxy resin (Oilized 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
[0057]
In the same manner as in Example 1, the obtained thermal transfer recording medium was formed on the intermediate transfer foil with a full-color image consisting of only area gradations, and the white concealment layer was transferred onto the image, and the adhesive layer was further transferred to transfer the object ( The image was transferred by pressing with a hot roll at 180 ° C. from the back surface of the intermediate transfer foil in a superimposed manner.
[0058]
Then, change the resin type and ratio as shown in the table below, create a thermal transfer recording medium and an intermediate transfer foil in the same way as in Examples 1 and 2, transfer the image to the intermediate transfer foil, and re-transfer to the transfer object (aluminum plate). Transcription was performed.
[0059]
[Table 1]

[0060]
In this table, the composition represents parts by weight, and the coating amount represents the layer thickness in μm.
[0061]
The spherical softening point, glass transition point, and molecular weight of the resin used are shown in the following table.
[0062]
[Table 2]

[0063]
The transferred material obtained with the above configuration was evaluated for image quality and durability. The evaluation results are as follows.
[0064]
[Table 3]

[0065]
As shown in the above table, the thermal transfer recording media according to the present invention (Examples 1 to 6) are such that full-color images produced in gradation reproducibility are faithfully reproduced from the highlight portion to the shadow portion at a high density and further after recording. Thus, an excellent thermal transfer recording medium having the durability of the image can be obtained, and the object of the present invention has been achieved.
[0066]
【The invention's effect】
According to the present invention, a color pigment, a binder resin, and colorless fine particles are contained in a thermal transfer recording layer, and the thermal transfer recording layer is thermally transferred onto an intermediate transfer foil from which an image receiving layer can be peeled by a thermal head printer, and the gradation based on area gradation is used. An image with excellent tonal reproducibility can be formed, a white hiding layer can be arbitrarily transferred onto the image, and a transparent adhesive layer can be further transferred to the image receiving layer. It is possible to provide a thermal transfer recording medium that can be transferred, and particularly a thermal transfer recording medium that can transfer an arbitrary full-color image onto a metal, glass, or the like, and is excellent in storability and mechanical strength of the image after transfer.
[Brief description of the drawings]
FIGS. 1A and 1B illustrate an embodiment of a thermal transfer sheet (thermal transfer recording medium) according to the present invention, in which FIG. 1A is a plan view and FIG.
FIGS. 2A and 2B illustrate another embodiment of the thermal transfer sheet (thermal transfer recording medium) of the present invention, in which FIG. 2A is a plan view and FIG.
[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

Claims (7)

A thermal transfer recording medium having a thermal transfer recording layer that is transferred by melting or softening by heat to at least one of the substrates ,
A thermal transfer recording layer mainly composed of colorless or light-colored fine particles, a colored pigment, and a resin has at least three colors of cyan, magenta, and yellow, and a white hiding layer and a transparent adhesive layer along the longitudinal direction of the support. Ri Ah provided by sequentially repeating colored separately, the composition for forming a thermal transfer recording layer of each color, that the solid content per 100 parts by weight, the coloring pigment is 19 to 30 parts by weight, the resin is 40 to 80 parts by weight Amorphous organic polymer having a composition of 1 to 30 parts by weight of colorless or light-colored fine particles, a film thickness of 0.2 to 1.0 μm, and a thermal transfer recording layer and a white concealing layer resin of the same color. der is, the composition for forming the white concealing layer, relative to the total solid amount 100 parts by weight, the thermal transfer recording white pigment is characterized in that 20 to 70 parts by weight, the resin is 30 to 80 parts by weight Medium. The thermal transfer recording medium 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. 2. The thermal transfer recording medium 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 of 40 to 100 ° C. 3. 2. The thermal transfer recording medium according to claim 1, wherein 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. 5. 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. 6. The thermal transfer recording medium according to claim 1, wherein the transparent adhesive layer contains a resin of the same type as the resin in the thermal transfer recording layer and the white hiding layer. Using the thermal transfer recording medium according to claim 1, printing is performed in advance on an intermediate transfer medium having at least a transferable image receiving layer, and the image receiving layer of the printed intermediate transfer medium is transferred to a target transfer target. And a thermal transfer recording method.

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