JP2776903C - - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a thermal transfer recording medium. More specifically, the present invention relates to a thermal transfer recording medium. The present invention relates to a heat-sensitive transfer recording medium which has a low glossiness, can provide a legible printed image, has excellent confidentiality, generates few voids, and has a high resolution. [Related Art and Problems to be Solved by the Invention] In recent years, by adopting a thermal transfer recording method for a facsimile, storage stability of a recorded image is improved as compared with a thermal coloring method used for a conventional facsimile. At the same time, attempts have been made to enable printing on plain paper. However, a printed image obtained from a conventional thermal transfer recording medium has a problem that the glossiness of the surface is high and it is difficult to read. Therefore, for example, by providing a mat layer containing a resin and a matting pigment between the support and the ink layer, a thermal transfer recording medium for removing gloss of a printed image, a support and an ink layer There has been proposed a thermal transfer recording medium or the like in which an anchor layer that forms fine irregularities is provided on the peeled surface of the ink layer to remove gloss of a printed image. However, in these thermal transfer recording media, the glossiness of the printed image is removed, but when used in a high-temperature environment such as a facsimile machine where the power is on all day and heat is easily stored, for example, as shown in FIG. Thermal transfer recording medium,
Since the ink layer A containing the heat-fusible substance is easily separated inside the ink layer, separation at the interface C with the mat layer (or anchor layer) B, which is the intended separation surface of the ink layer A, is prevented. As a result, there is a problem that the film thickness of the ink layer A transferred onto the transfer receiving medium becomes thin and the print density decreases. In addition, in FIG. 2, D is a support. Further, in the conventional thermal transfer recording medium, after the ink layer has been transferred to the transfer receiving body, a so-called white spot that is readable and corresponding to the shape of the printed image occurs, so that the problem of poor confidentiality is caused. is there. Further, in general, in order to improve the quality of a printed image formed by a thermal transfer recording medium and obtain a clear printed image, it is desired that the generation of voids be small and the resolving power be high. The present invention has been made based on the above circumstances. An object of the present invention is to provide a printed image in which the density does not decrease even in a high-temperature environment, and the glossiness of the surface is low and the legibility is easy to read.
In addition, it is an object of the present invention to provide a thermal transfer recording medium which is free from voids and has high resolution. [Means for Solving the Problems] In order to solve the above problems, as a result of intensive studies by the present inventors, a specific non-transfer layer containing a specific substance is provided between the support and the transfer layer. In the specific thermal transfer recording medium provided, surprisingly, even in a high-temperature environment, the transfer layer peels off due to cohesive failure near the interface with the non-transfer layer in the transfer layer, so that the density does not decrease, Further, the present inventors have found that a printed image having a low glossiness on the surface and which is easy to read can be obtained, excellent in confidentiality, little occurrence of voids, and high in resolving power. The structure of the invention according to claim 1 has a non-transfer layer containing a thermoplastic polymer and a color material between a support and a transfer layer containing a heat-fusible substance and a color material, and the non-transfer layer. Wherein the thermoplastic polymer is a mixture of at least one member selected from the following group A and at least one member selected from the following B group. [Group A] α-olefin polymer, α-olefin-maleic anhydride copolymer, α-olefin-alkyl (meth) acrylate copolymer, α-olefin-vinyl acetate copolymer, α-olefin (meth) Acrylic acid copolymer, vinyl acetate polymer, alkyl (meth) acrylate polymer, (meth) acrylic acid polymer, styrene elastomer. [Group B] Polyester resin, polyurethane resin, polyvinyl chloride. Hereinafter, the thermal transfer recording medium of the present invention will be described in detail for a support, a non-transfer layer, a transfer layer, and the like. —Support— The support in the thermal transfer recording medium of the present invention preferably has good heat resistance and high dimensional stability. Examples of the material include papers such as plain paper, condenser paper, laminated paper, and coated paper; resin films such as polyethylene, polyethylene terephthalate, polystyrene, polypropylene, and polyimide; composites of paper and resin film; and aluminum foil. Any of metal sheets and the like are suitably used. The thickness of the support is usually 30 μm or less, preferably 2 to 6 μm.
When the thickness of the support exceeds 30 μm, the thermal conductivity is deteriorated, and the print quality may be deteriorated. In the thermal transfer recording medium of the present invention, the configuration on the back side of the support is arbitrary, and for example, a backing layer such as an anti-sticking layer may be provided. —Non-Transfer Layer— One of the important points in the present invention is that at least one selected from the group A and at least one selected from the group B between the support and the transfer layer described in detail below. It is to have a non-transfer layer containing a mixture with one kind. By providing the non-transfer layer, in the thermal transfer recording medium of the present invention, when the transfer layer to be described in detail below is separated from the support side, the transfer layer is stable near the interface between the non-transfer layer and the transfer layer even in a high temperature environment. It is possible to form a clear printed image that is easy to read because it has high density and low glossiness on the surface while achieving high density. More specifically, even in a high-temperature environment, stable cohesive failure peeling is realized near the interface between the non-transfer layer and the transfer layer, so that the transfer layer moves to the medium to be transferred at a predetermined thickness and the density does not decrease, By forming fine irregularities on the transfer layer where the transfer layer is peeled off, that is, on the surface of the print image, a print image with low glossiness on the surface can be formed. In addition, the non-transfer layer remains on the support even after the transfer layer has been transferred to the medium to be transferred, and contains a coloring material, so that the occurrence of the so-called white spots described above is prevented,
The thermal transfer recording medium of the present invention has excellent confidentiality. Such an action or function of the non-transfer layer is mainly brought about by the thermoplastic polymer and the coloring material contained in the non-transfer layer. A thermoplastic polymer selected from the group A described above [hereinafter, this may be referred to as a polymer (I). ] And a thermoplastic polymer selected from the aforementioned group B [hereinafter, this may be referred to as a polymer (II). The above polymer in a mixture with
The ratio of each of I) and the polymer (II) is such that the polymer (I) is usually 3 to 80% by weight, preferably 3 to 50% by weight, and the polymer (II) is usually 3 to 50% by weight. It is 80% by weight, preferably 20-60% by weight. If the proportion of the polymer (I) in the mixture is less than 3% by weight, the adhesive strength between the non-transfer layer and the transfer layer may be reduced, which may make the mixture unsuitable for practical use. On the other hand, when the proportion of the polymer (II) in the mixture is less than 3% by weight, the adhesive force between the non-transfer layer and the support is reduced, and even after the transfer layer is transferred to the transfer medium. The non-transfer layer to be left on the support may peel off from the support. In any case, if the ratio of each of the polymer (I) and the polymer (II) is out of the above range, the effect of the present invention may not be sufficiently exerted. The polymer (I) has a melt index (MI value) of usually from 1 to 3,000.
0, preferably a compound in the range of 5 to 1,000, specifically, an α-olefin polymer, α-olefin-maleic anhydride copolymer, α
-Olefin-alkyl (meth) acrylate copolymer, α-olefin-vinyl acetate copolymer, α-olefin (meth) acrylic acid copolymer, vinyl acetate polymer, alkyl (meth) acrylate polymer, (meth) It is preferably at least one of an acrylic acid polymer and a styrene-based elastomer. More specifically, α-olefin polymers such as ethylene polymer and propylene polymer; maleic anhydride-modified ethylene-vinyl acetate copolymer (maleic anhydride-modified)
Α-olefin-maleic anhydride copolymer such as EVA); α-olefin-alkyl (meth) acrylate copolymer such as ethylene-ethyl acrylate copolymer (EEA) and ethylene-methyl methacrylate copolymer (EMMA) Α-olefin-vinyl acetate copolymer such as ethylene-vinyl acetate copolymer (EVA); vinyl acetate polymer; alkyl (meth) such as methyl methacrylate (MMA) polymer and butyl methacrylate (BMA) polymer. A) acrylate polymers; acrylic acid (AA) polymers, methacrylic acid (MAA) polymers; and polystyrene, styrene-acryl copolymers, polybutadiene-styrene copolymers, polyisoprene-styrene copolymers, polyolefin-styrene copolymers. At least one selected from styrene-based elastomers such as coalescing is preferred. Among the compounds selected from Group A, preferred are ethylene-vinyl acetate copolymer (EVA), ethylene ethyl acrylate, and styrene-based elastomer, and particularly preferred is styrene-based elastomer. The polymer (II) is a compound having a number average molecular weight in the range of usually 1,000 to 100,000, preferably 2,000 to 50,000, and specifically, a polyester resin, a polyurethane resin and a polyether selected from the group B. It is preferably one of vinyl chloride. Among these, polyester resins are preferred. Preferred examples of the combination of the polymer (I) and the polymer (II) contained in the non-transfer layer include, for example, a combination of an ethylene-vinyl acetate copolymer and a polyester resin. The content of the mixture of the polymer (I) and the polymer (II) in the non-transfer layer is 10% by weight or more, preferably 20 to 80% by weight. The non-transfer layer contains the coloring material together with the thermoplastic polymer. The coloring material has an effect of preventing the above-mentioned so-called white spots from occurring after the transfer layer is transferred to the transfer medium. Therefore, it is preferable that the color of the color material contained in the transfer layer is the same as the color of the color material in the transfer layer described in detail below. As the coloring material, those similar to the coloring material in the thermosoftening coloring material layer described in detail below can be suitably used. The content of the coloring material in the non-transfer layer is usually 80% by weight or less, preferably 10 to
60% by weight. The non-transfer layer may contain a heat-fusible substance together with the thermoplastic polymer and the coloring material. As the heat-fusible substance, the same heat-fusible substance that can be contained in the transfer layer described in detail below can be suitably used. The content of the heat-fusible substance when the non-transfer layer contains the heat-fusible substance,
Usually, it is 50% by weight or less, preferably 2 to 50% by weight. The non-transfer layer containing the above components can be coated on the support by a coating method such as an aqueous coating method, a coating method using an organic solvent, or a hot melt coating method. The layer thickness of the non-transfer layer is usually in the range of 0.3 to 5 μm, preferably 0.2 to 2 μm.
m. By setting this layer thickness within the above range, the object of the present invention can be sufficiently achieved. On this non-transfer layer, a transfer layer described below is laminated adjacent thereto. —Transfer Layer— The transfer layer contains a heat-fusible substance and a coloring material. Examples of the heat-fusible substance include vegetable waxes such as carnauba wax, wood wax, ouriculi wax and espar wax; animal waxes such as beeswax, insect wax, shellac wax and spermaceti; paraffin wax, microcrystal wax, polyethylene wax, ester Petroleum waxes such as waxes and acid waxes; and waxes such as mineral waxes such as montan wax, ozokerite and ceresin. In addition to these waxes, palmitic acid, stearic acid, margaric acid and behen Higher fatty acids such as acids; palmityl alcohol;
Higher alcohols such as stearyl alcohol, behenyl alcohol, marganyl alcohol, myricyl alcohol and eicosanol; higher fatty acid esters such as cetyl palmitate, myricyl palmitate, cetyl stearate and myricyl stearate; acetamide, propionamide, palmitamide, Amides such as stearic acid amide and amide wax; and higher amines such as stearylamine, behenylamine and palmitylamine. These may be used alone or in combination of two or more. Among these, preferred are those having a melting point of 50 to 120 measured using a Yanagimoto MJP-2 type.
Wax in the range of ° C. The content of the heat-fusible substance in the transfer layer is usually preferably in the range of 30 to 90% by weight or less. Examples of the coloring material include pigments such as inorganic pigments and organic pigments, and dyes. Examples of the inorganic pigment include titanium dioxide, carbon black, zinc oxide, Prussian blue, cadmium sulfide, iron oxide, and chromates of lead, zinc, barium, and calcium. Examples of the organic pigment include azo-based, thioindigo-based, anthraquinone-based, anthranthrone-based, and triphenedioxazine-based pigments, vat dye pigments, phthalocyanine pigments such as copper phthalocyanine and its derivatives, and quinacridone pigments. Examples of the organic dye include an acid dye, a direct dye, a disperse dye, an oil-soluble dye, and a metal-containing oil-soluble dye. Among these various coloring materials, carbon black is particularly preferred. The content of the coloring material in the transfer layer is usually in the range of 5 to 30% by weight, preferably in the range of 10 to 25% by weight. The transfer layer may further contain a thermoplastic resin together with the hot-melt substance and the coloring material. When the thermoplastic resin is contained, the cohesive force in the transfer layer can be easily adjusted. Examples of the thermoplastic resin include polyethylene and its copolymer resin, polypropylene resin, polystyrene and its copolymer resin, methyl methacrylate resin, vinyl chloride resin and its copolymer resin, vinylidene chloride resin, vinyl acetate resin, and cellulose resin. Resins, ionomer resins, polyamide resins, polyethers, polycarbonates, polyester resins, polyphenylene oxide and noryl resins, polysulfones, fluorine resins, silicone resins, and the like. These may be used alone or in combination of two or more. Among the thermoplastic resins, preferred is an ethylene copolymer. Examples of the ethylene copolymer include an ethylene-vinyl acetate copolymer, an ethylene-ethyl acrylate copolymer, an ethylene-methyl methacrylate copolymer,
Examples include ethylene-isobutyl acrylate copolymer, ethylene-acrylic acid copolymer, ethylene-vinyl alcohol copolymer, ethylene-vinyl chloride copolymer, and ethylene-acrylate metal salt copolymer. When the thermoplastic resin is used, the content of the thermoplastic resin component in the transfer layer is usually 50% by weight or less, and preferably 40% by weight or less. Further, the transfer layer may contain, in addition to the above components, a surfactant such as a compound containing a polyoxyethylene chain. The transfer layer may further contain inorganic or organic fine particles (metal powder, silica gel, etc.) and oils (linseed oil, mineral oil, etc.). The transfer layer can be coated on the non-transfer layer by using a coating method such as an aqueous coating method or a coating method using an organic solvent. The thickness of the transfer layer is usually in the range of 0.5 to 8 μm, preferably 1.5 to 6.
It is in the range of 0 μm. -Others- The heat-sensitive transfer recording medium of the present invention is usually prepared by applying the non-transfer layer and the transfer layer on the support in this order, and then optionally through a drying step, a surface smoothing step, and the like. It can be manufactured by cutting into the shape of. The thermal transfer recording medium thus obtained can be used in the form of a wide tape or a typewriter ribbon generally used for a line printer or the like, but the planar shape of the thermal transfer recording medium of the present invention can be used. Preferred is a sheet having substantially the same width as the recording paper used in the line printer. Although the thermal transfer method using the thermal transfer recording medium of the present invention is not different from the normal thermal transfer recording method, a case where a most typical thermal head is used as a heat source will be described as an example. First, the transfer layer of the thermal transfer recording medium and the medium to be transferred, such as plain paper, are brought into close contact with each other, and a heat pulse is applied by a thermal head to locally heat the heat-softening color material layer corresponding to a desired printing or transfer pattern. I do. The temperature of the heated portion of the transfer layer rises, for example, as shown in FIG. 1 (a), the transfer layer 1 softens quickly and peels off from the vicinity of the interface with the non-transfer layer 2 due to cohesive failure. Is transferred onto the transfer-receiving medium. After the transfer layer 1 is transferred, the first
As shown in FIG. 2B, the non-transfer layer 2 remains on the support 3. [Examples] Next, examples of the present invention and comparative examples are shown, and the present invention will be described more specifically. (Example 1) Solvent coating using a wire bar on a 4.5 μm-thick polyethylene terephthalate film with the following non-transfer layer composition over a length corresponding to the width of JIS A4 paper so as to have a layer thickness of 1 μm. The non-transferable layer was formed on the thermal transfer recording medium of the present invention by a coating method. Non-transfer layer composition Ethylene-vinyl acetate copolymer (vinyl acetate content 28% by weight) 20% by weight Polyester resin 60% by weight ["Vylon 200" manufactured by Toyobo Co., Ltd.] Carbon black 20 Next, the following heat-softening colorant layer composition was coated on the non-transfer layer by a hot melt coating method using gravure so as to have a thickness of 4 μm to form a transfer layer. A thermal transfer recording medium was obtained. Transfer layer composition Carbon black: 20% by weight Ethylene-vinyl acetate copolymer: 10% by weight Paraffin wax: 50% by weight Oxidized wax: 20% by weight The obtained thermal transfer recording medium is transferred to a thermal printer (260 mm width). Line head, 180D
PI (platen rubber hardness: 40 degrees) was recorded (printed) on plain paper (Beck smoothness: 20 seconds), and the gloss, resolution, voids and density of the printed image were evaluated. The results are shown in Table 1. The glossiness, resolution, void, density reduction, and confidentiality of the printed image were evaluated as follows. Glossiness: Using a glossmeter, measure the glossiness of the printed image under the condition that both the incident angle and the reflection angle are 60 °.
15 or more was evaluated as x. Resolving power: ケ イ: no blurring was observed by visually observing the blur of the 1-dot key line, ○: slight blurring was observed, and x: blurred. Void: Observed visually. Density reduction: Printing is performed under the conditions of a machine temperature of 40 ° C.
The above was evaluated as ○. Confidentiality: The prints after printing were visually observed by reflected light, and those with some missing were rated as x, and those without any missing were rated as o. (Example 2) In the same manner as in Example 1, except that the following non-transfer layer composition was used in place of the non-transfer layer composition used in Example 1, the following non-transfer layer composition was used. did. The results are shown in Table 1. Non-transfer layer composition Styrene-butadiene-styrene copolymer ["Clayton G1300" manufactured by Shell Chemical Co.] ... 10% by weight polyester resin ... 80% by weight ["UE3600"; manufactured by Unitika Ltd.] Carbon black ... ... 10% by weight (Comparative Example 1) Same as Example 1 except that the following non-transfer layer composition was used in place of the non-transfer layer composition used in Example 1 Then, a non-transfer layer and a transfer layer were laminated on the support in this order to produce a thermal transfer recording medium, and the thermal transfer recording medium was evaluated. The results are shown in Table 1. Non-transfer layer composition Ethylene-vinyl acetate copolymer 80% by weight (vinyl acetate content 28% by weight) Carbon black 20% by weight (Comparative Example 2) Used in Example 1 in Example 1 A non-transfer layer and a transfer layer were laminated in this order on a support in the same manner as in Example 1 except that the following non-transfer layer composition was used instead of the non-transfer layer composition described above. A thermal transfer recording medium was manufactured, and the thermal transfer recording medium was evaluated. The results are shown in Table 1. Non-transfer layer composition Polyester resin 80% by weight [Byron 200; manufactured by Toyobo Co., Ltd.] Carbon black 20% by weight (Comparative Example 3) In Example 1, used in Example 1 A non-transfer layer and a transfer layer were laminated in this order on a support in the same manner as in Example 1 except that the following non-transfer layer composition was used instead of the non-transfer layer composition described above. A thermal transfer recording medium was manufactured, and the thermal transfer recording medium was evaluated. The results are shown in Table 1. Non-transfer layer composition Polyester resin 60% by weight Carbon black 20% by weight Fluororesin particles (average particle diameter 0.3φ) 20% by weight (Evaluation) As is evident from Table 1, the thermal transfer recording medium of the present invention has no reduction in density even in a high-temperature environment, has excellent confidentiality, has high resolution, and has little voids. It was confirmed that a high quality printed image could be formed. [Effects of the Invention] According to the present invention, (1) Since the non-transfer layer between the support and the transfer layer contains a specific compound, it is always transferred even in a high-temperature environment such as a line printer of a facsimile machine. The transfer layer peels off due to stable cohesive destruction occurring near the interface between the layer and the non-transfer layer, so that there is no decrease in density and the printed image has low gloss on the surface of the printed image and is easy to read. (2) After the transfer layer is transferred onto the medium to be transferred, the non-transfer layer remaining on the support contains a coloring material, so that a readable so-called white spot may occur. Without
(3) It is possible to provide a high-performance thermal transfer recording medium having various advantages such as (3) high resolution and low occurrence of voids.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 (a) and 1 (b) are cross-sectional views showing the relationship between a transfer layer and a non-transfer layer in a thermal transfer recording medium of the present invention, and FIG. FIG. 2 is an explanatory cross-sectional view illustrating an example of the thermal transfer recording medium of FIG. 1 ... transfer layer, 2 ... non-transfer layer, 3 ... support

Claims (1)

Claims (1) A non-transfer layer containing a thermoplastic polymer and a color material is provided between a support and a transfer layer containing a heat-fusible substance and a color material, and the non-transfer layer is Wherein the thermoplastic polymer is a mixture of at least one selected from the following group A and at least one selected from the following group B. [Group A] α-olefin polymer, α-olefin-maleic anhydride copolymer, α-olefin-alkyl (meth) acrylate copolymer, α-olefin-vinyl acetate copolymer, α-olefin- (meth ) Acrylic acid copolymers, vinyl acetate polymers, alkyl (meth) acrylate polymers, (meth) acrylic acid polymers, styrene elastomers. [Group B] Polyester resin, polyurethane resin, polyvinyl chloride.