JP2001219655A - Thermal transfer recording medium and image forming method - Google Patents

Abstract

(57) [Summary] [Problem] To prevent a decrease in resolution due to ink bleeding. Also, if wax is used, the durability of the transferred image is insufficient when the image is rubbed by hand, and the image is obtained. To improve the durability of the thermal transfer recording layer at the time of thermal transfer, especially when the thermal transfer sheet base material is peeled off, and Provided is a thermal transfer recording medium (thermal transfer ribbon) capable of simultaneously achieving sufficient optical density of a transferred image and sufficiently achieving these. Kind Code: A1 Abstract: A thermal transfer recording medium in which a thermal transfer recording layer formed from a composition containing at least a color pigment, an organic resin binder, and colorless or light-colored fine particles on a support is provided. 0.5-layer thickness
1.0 μm, and the organic resin binder is vinyl chloride having an average molecular weight of 10,000 to 20,000.
It is a vinyl acetate copolymer resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal head printer, in which a thermal transfer recording layer containing a color pigment is thermally transferred onto an image receiving sheet. The present invention relates to a thermal transfer recording medium for forming a color image and the like and an image forming method using the same.

[0002]

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

In the sublimation transfer system, a thermal transfer recording medium having a sublimable (heat transferable) dye and a binder resin provided on a support is superimposed on an image receiving sheet, and the thermal transfer recording is performed in accordance with the amount of heat of a 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-migrating) dye, the formed image is inferior in durability and its use in fields requiring heat resistance and light resistance is limited. You. In addition, since the thermal recording sensitivity is lower than that of the melt transfer method, high printing energy is required, and the size and weight of printers driven by batteries such as dry batteries can be reduced, and high-speed recording materials using high-resolution thermal heads expected to be used in the future are expected. Have the disadvantages that they are not suitable.

On the other hand, the melt transfer method uses a transfer sheet having a heat-meltable ink transfer layer made of a coloring material such as a pigment or a dye and a binder such as a wax on a support, and uses a heating device such as a thermal head. And applying an energy corresponding to the image information to form an image by fusing the ink transfer layer on the image receiving sheet. An image formed by the fusion transfer method has high density and excellent sharpness, and is suitable for recording a binary image such as a character or a line drawing.

A color image can also be formed by forming an image on a receiving sheet using a thermal transfer sheet made of yellow, magenta, cyan, and black. As such a thermal transfer sheet for forming a color image, there is JP-B-63-65029.

[0007]

However, in the case of the thermal transfer sheet described in JP-B-63-65029,
Since the crystalline wax having a low melting point is used as a binder for the ink layer, the resolution is likely to decrease due to ink bleeding. Further, the fixing strength of the transferred image is low, and if the image portion is rubbed with hand, the image portion may come off and fall off.

Various proposals have been made as methods for solving such a phenomenon. For example, Japanese Unexamined Patent Application Publication No.
No. 92 proposes a heat-sensitive transfer sheet having a heat-sensitive ink layer comprising 65% or more of an amorphous polymer, a release material and a colorant. However, Japanese Unexamined Patent Publication No.
The thermal transfer sheet described in JP-A-244592 also contains a crystalline wax, so that the fixing strength at the portion where the superimposed printing of each color is performed is insufficient.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and is intended to reduce the reduction in resolution due to ink bleeding caused by the use of a low-melting crystalline wax as a binder for an ink layer. In addition, if the wax is used, the durability of the transferred image will be insufficient if the image is rubbed by hand, and the image will be easily removed and the durability will be improved. In particular, the thermal transfer recording layer has good foil-cutting properties during thermal transfer, has a high optical density of a transferred image, and has excellent halftone expression power by dot area gradation. It is an object of the present invention to provide a thermal transfer recording medium (thermal transfer ribbon) which can be used.

[0010]

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 fusion transfer method.

That is, according to the invention of claim 1 of the present invention, a thermal transfer recording layer formed of a composition containing at least a color pigment, an organic resin binder, and colorless or light-colored fine particles on a support is provided. In the provided thermal transfer recording medium, the thermal transfer recording layer has a thickness in the range of 0.5 to 1.0 μm, and the organic resin binder has an average molecular weight of 10,000 to 20,000. The thermal transfer recording medium is characterized in that:

According to a second aspect of the present invention, there is provided the thermal transfer recording medium of the first aspect, wherein the composition forming the thermal transfer recording layer has a total solid content of 100%.
A thermal transfer recording medium having a composition of 20 to 30 parts by weight of a coloring pigment, 40 to 70 parts by weight of polyvinyl chloride resin, and 1 to 30 parts by weight of colorless or light-colored fine particles with respect to parts by weight.

According to a third aspect of the present invention, in the thermal transfer recording medium according to the first or second aspect, the vinyl chloride-vinyl acetate copolymer resin comprises maleic acid as a copolymerization component. Is a vinyl chloride-vinyl acetate-maleic acid copolymer resin containing 1 to 5% by weight of a thermal transfer recording medium.

According to a fourth aspect of the present invention, in the thermal transfer recording medium according to any one of the first to third aspects, the coloring pigment has an average particle diameter of 50 or less.
A thermal transfer recording medium characterized by being in the range of ５００500 nm.

According to a fifth aspect of the present invention, in the thermal transfer recording medium according to any one of the first to fourth aspects, the colorless or light-colored fine particles have an average particle diameter of 10 to 10. A thermal transfer recording medium having a range of 300 nm and smaller than the average particle size of the coloring pigment.

According to a sixth aspect of the present invention, in the thermal transfer recording medium according to any one of the first to fifth aspects, the colorless or light-colored fine particles are silica. This is a characteristic thermal transfer recording medium.

According to a seventh aspect of the present invention, in the thermal transfer recording medium according to any one of the first to sixth aspects, the thermal transfer recording layer includes three of cyan, magenta, and yellow. Color or black,
A thermal transfer recording medium characterized in that four colors of cyan, magenta and yellow are repeatedly arranged on a support in a proper order along the longitudinal direction and repeatedly provided.

Next, according to an eighth aspect of the present invention, a thermal transfer recording layer of the thermal transfer recording medium according to any one of the first to seventh aspects is formed on an image receiving sheet by using a thermal head printer. An image forming method in which an image is formed by thermal transfer and area gradation, wherein the image is thermally transferred onto the image receiving layer of an image receiving sheet on which an image receiving layer mainly composed of a vinyl chloride-vinyl acetate copolymer resin is formed by coating. An image forming method characterized by the following.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The principle of transfer of a thermal transfer recording medium according to the present invention is as follows. Heat is applied to a thermal transfer recording material by a thermal medium such as a thermal head, and the acrylic resin in the thermal transfer recording layer is thermally melted. Rather, it is in a softened or semi-molten state, the adhesiveness to the image receiving layer is developed at the same time, the adhesiveness to the medium substrate is reduced, and the image is recorded by the thermal transfer recording layer adhering to the image receiving sheet. Is done. This transfer principle is also considered to be related to the very thin thickness of the thermal transfer recording layer, and rather than the traditional so-called hot-melt transfer, a thermal adhesive thin film peeling method (a term used in this method). It is considered that the transfer belongs to a type that can be referred to as a type described in JP-A-7-117359.

As a result, when printing is performed by overlapping at least two or more colors, a clear print can be obtained without ink bleeding. Also, the transferred recorded image has excellent mechanical strength,
The characteristic that the halftone expression power by the dot area gradation is excellent is obtained.

Hereinafter, the thermal transfer recording medium of the present invention will be described in detail. FIG. 1 shows a thermal transfer recording medium 1 according to the present invention in which a thermal transfer recording layer 3 is provided on a support 2.

As the support 2 that can be used in the present invention, those generally used for a sublimation transfer type or a melt transfer type can be used. In particular,
Polyethylene terephthalate, polyethylene naphthalate, polypropylene, cellophane, polycarbonate,
Examples thereof include plastic films such as polyvinyl chloride, polystyrene, polyimide, nylon, and polyvinylidene chloride, and papers such as condenser paper and paraffin paper. Particularly preferred is polyethylene terephthalate (PET; saturated polyester).

The thickness of the support 2 is 2 to 50 μm, more preferably 2 to 10 μm. The thermal transfer recording layer 3 is composed of a color pigment, vinyl chloride resin and colorless or light-colored fine particles.

The polyvinyl chloride resin contained in the thermal transfer recording layer 3 has a Tg of from 50 ° C. to 9 ° C. in consideration of printability to a heat medium such as a thermal head and durability of an image after transfer recording.
It is preferable to use one in the range of 0 ° C. Further, the polyvinyl chloride resin used as a main material in the thermal transfer recording layer of the present invention preferably has an average molecular weight of 10,000 to 20,000.
Is good. Here, the average molecular weight means a weight average molecular weight, and in the present invention, this is hereinafter simply referred to as an average molecular weight.

If the average molecular weight of the vinyl chloride resin is lower than the lower limit (less than 10,000), the stability of the vinyl chloride resin is usually too poor, and yellowing, browning, Discoloration occurs greatly in black and the like. Further, the durability of the image to rubbing is not sufficient, and if the image is rubbed by hand, tailing tends to occur in the transferred image, which is not preferable. Conversely, if the average molecular weight is higher than the upper limit, the heat transfer layer (cutting the film) is deteriorated in order to deteriorate the transferability of the heat-sensitive transfer layer (exceeding 20,000). Resolution becomes worse.

Further, when a vinyl chloride-vinyl acetate / maleic acid copolymer resin containing 1 to 5% of a maleic acid component is used as the vinyl chloride vinegar resin, the alcohol resistance of the image is high, which is particularly preferable.

The vinyl chloride vinyl acetate resin used in the present invention may be any copolymer as long as it contains at least 70% of the total of the vinyl chloride component and the vinyl acetate component. May be copolymerized.

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

The color pigment used as a main material in the thermal transfer recording layer of the present invention is particularly preferably contained in the thermal transfer recording layer in an amount of 20 to 30 parts by weight. More preferably, the average particle size of the color pigment is 50 to 500.
in the range of nm.

If the proportion of the coloring pigment in the thermal transfer recording layer is less than the lower limit (less than 20 parts by weight), it is difficult to obtain a sufficient optical density of the transferred image, which is not preferable. Conversely, if this ratio exceeds the upper limit, (3
0 parts by weight), the adhesion to the image receiving layer side during thermal transfer is too weak, and the fixability, especially at the overlapping portions of the colors, is reduced, resulting in poor image durability. Further, if the average particle size of the color pigment contained in the thermal transfer recording layer is less than the lower limit (less than 50 nm), light resistance, which is one of the advantages of the pigment, deteriorates, which is not preferable. If the average particle diameter exceeds the upper limit, the color developability of the pigment (exceeding 500 nm) decreases, and it is difficult to obtain a sufficient optical density of a transferred image, which is not preferable.

The average particle diameter mentioned here can be measured by a method such as AUTOSIZER2C manufactured by MARVERUN by a light scattering method, a Coulter counter method, image processing from SEM observation images, and the like.

The colorless or light-colored fine particles contained in the thermal transfer recording layer 3 are necessary for improving the transferability at the time of thermal transfer, more specifically, the dot shape on which a transferred image is formed, and the gradation reproducibility. The reason why the colorless or light-colored component is used is to minimize the color development of a 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,
Examples include polyethylene powder, polymethyl methacrylate resin beads, polyurethane resin beads, benzoguanamine and melamine resin beads. Among the above, silica fine particles are particularly preferred.

In the present invention, the colorless or light-colored fine particles are added for the purpose of improving transferability (cutting property of foil).
This size is preferably smaller than the average particle size of the color pigment when the average particle size is in the range of 10 to 300 nm. Since the average particle diameter of the fine particles is smaller than that of the coloring pigment, the effect of improving the cut-off property of the thermal transfer recording layer, which cannot be achieved by using the coloring pigment alone, without impairing the coloring property of the pigment, is extremely high. Is very good in dot shape formed and gradation reproducibility. Further, as compared with the case where the amount of the coloring pigment is increased, since the average particle diameter is small, the weakening of the adhesive force to the image receiving layer can be minimized. If the average particle size is more than 300 nm, the effect of improving the cut-off property of the foil is weak, and the color development of the colored image formed by the thermal transfer is not preferred.

The composition of the composition for forming the thermal transfer recording layer 3 is such that the color pigment is 20 to 30 parts by weight, the vinyl chloride resin is 40 to 70 parts by weight, and the total solid content is 100 parts by weight. The colorless or light-colored fine particles are 1 to 30 parts by weight.

When the amount of the polyvinyl chloride resin is less than the above range, it is not preferable in that the film strength is reduced.
More specifically, it is not preferable because the dot shape on which the transfer image is formed and the gradation reproducibility deteriorate. When the number of colorless or light-colored fine particles is less than the above range, it is almost equivalent to no addition, and the transferability, specifically, the dot shape in which a transferred image is formed, is not preferable because there is no effect of improving the tone reproducibility and the like. Does not provide good fluidity of the ink, and also reduces the color development of the pigment because it is greater than the pigment content, and excessively deteriorates the adhesive force to the image receiving layer side during thermal transfer. The fixability at the overlapping portion of the color is reduced, and the durability of the image is deteriorated.

Various additives such as a pigment dispersant, a coating film stabilizer, an antioxidant, an antistatic agent, and a sensitizer may be added to the thermal transfer recording layer having the above composition, if necessary. You can also. The amount of addition is preferably 10 parts by weight or less based on 100 parts by weight of the composition for forming the thermal transfer recording layer.

The method for producing a thermal transfer recording medium of the present invention comprises the steps of: dispersing or dissolving a colorant, a vinyl chloride resin and colorless fine particles in a solvent on a substrate such as coated paper or plastic; It is formed by applying a solvent coat method such as a bar coat, a blade coat, an air knife coat, a gravure coat, a roll coat and the like, and drying to form a thermal transfer recording layer.

The thickness of the thermal transfer recording layer 3 is 0.5 to 1.0.
μm is desirable. When the film thickness is less than 0.5 μm, it is difficult to obtain a sufficient density, and when the film thickness is more than 1.0 μm, it becomes difficult to perform transfer according to the heat-generating portion of the thermal head. The gradation reproducibility is inferior.

When the thermal transfer recording layer 3 is transferred onto the image receiving sheet by applying heat from a side of the support 2 where the thermal transfer recording layer 3 is not provided, using a thermal head, the thermal head adheres to the support 2. In order to prevent the smooth running of the thermal transfer recording medium 1 from being hindered, it is desirable to provide the back coat layer 4 on the side of the support 2 where the thermal transfer recording layer 3 is not provided.

Materials used for the back coat layer 4 include nitrocellulose, saturated polyester resin (PET resin; polyethylene terephthalate resin),
An acrylic resin, a vinyl resin, or the like containing silicon oil, a silicon-modified resin, or the like can be given. Further, a crosslinking agent may be used in combination for the purpose of improving heat resistance. The coating thickness when providing the back coat layer 4 is preferably about 0.1 to 4 μm.

As the image receiving sheet used to form an image using the thermal transfer recording medium 1 as described above, paper such as high quality paper, coated paper, saturated polyester film (P
(ET film; polyethylene terephthalate film), a plastic film such as a polyvinyl chloride film and a polypropylene film, or a paper or a plastic film coated with an image receiving layer.

The image receiving layer used here is preferably composed mainly of vinyl chloride vinyl chloride resin. That is, by using the image receiving layer containing vinyl chloride resin as a main component, the heat transfer recording layer and the image receiving layer are satisfactorily formed by the heat during the thermal transfer even if the thermal transfer recording layer of the thermal transfer recording medium is not sufficiently melted during the thermal transfer. Since the printing is performed by bonding and sufficient foil cutting, transferability, more specifically, dot shape on which a transferred image is formed, gradation reproducibility, and the like are improved. Furthermore, the formed image has abrasion resistance,
It is excellent in image resistance such as scratch resistance.

Here, the range containing vinyl chloride resin as a main component means that, among the components contained in the image receiving layer, the vinyl chloride resin component is contained more than any other component. is there.

When it is difficult to form an image directly on a sheet on which an image is to be formed, it is possible to form an image once on the image receiving sheet and then re-transfer the transferred image onto the final sheet. good. Such an indirect transfer method not only widens the selectivity of the final sheet, but also provides a protective layer on the final transfer image by providing a protective layer on the image receiving sheet, thereby improving the image resistance and improving image resistance. By providing a security layer such as a hologram forming layer on the sheet, it is possible to improve the security of the final transfer image.

The means for applying thermal energy for obtaining a gradation image expression by area gradation using the thermal transfer recording medium of the present invention and the image receiving sheet as described above may be any of conventionally known applying means. Can be used, and a gradation image can be obtained by controlling the heat energy.

[0046]

Next, the present invention will be described more specifically with reference to examples. In the following description, parts and% are by weight (parts by weight or% by weight) unless otherwise specified.

<Example 1> First, an ink composition having the following composition was prepared as an ink for a thermal transfer recording layer. (Cyan ink) Phthalocyanine blue 9 parts PVC resin (VROH, manufactured by Union Carbide) 20 parts Molecular weight Mn 15000 Colorless fine particles (silica) 5 parts (Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) Methyl ethyl ketone 67 parts (magenta) Ink) Carmine 6B 9 parts PVC resin (VROH manufactured by Union Carbide) 20 parts Molecular weight Mn 15000 Colorless fine particles (silica) 5 parts (Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) Methyl ethyl ketone 67 parts (yellow ink) Disazo Yellow 9 parts PVC resin (VROH, manufactured by Union Carbide Co., Ltd.) 20 parts Molecular weight Mn15000 Colorless fine particles (silica) 5 parts (Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) Methyl ethyl ketone 67 parts

The ink for a thermal transfer recording layer having the above formulation was applied to a 5.4 μm-thick polyethylene terephthalate film whose back surface was heat-treated so as to have a dry film thickness of 0.7 μm, and then dried. A thermal transfer recording medium was obtained.

Next, the following image-receiving layer ink was applied to the easy-adhesion surface of a 100-μm easily-adhesive polyester film (saturated polyester film; polyethylene terephthalate film) so as to have a dry film thickness of 5 μm and dried. An image receiving sheet was obtained. (Image-receiving layer ink) PVC resin (VMCC, manufactured by Union Carbide) 20 parts Molecular weight Mn 19000 Methyl ethyl ketone 70 parts

First, the surface of the thermal transfer recording layer of the obtained thermal transfer recording medium for cyan is superimposed on the image receiving sheet, and heated using a thermal head, and the cyan image is formed on the image receiving sheet by area gradation according to the heat generating portion of the thermal head. I got Next, using a magenta thermal transfer recording medium, a magenta image based on area gradation was formed on an image receiving sheet on which a cyan image was formed in the same manner as for cyan. Similarly, a yellow image was formed, and a color image consisting only of area gradation was formed on the image receiving sheet.

Example 2 A thermal transfer recording medium was prepared and a color image was formed in the same manner as in Example 1 except that the ink for the thermal transfer recording layer in Example 1 was changed to the following formulation. (Cyan ink) Phthalocyanine blue 9 parts PVC resin (VMCC manufactured by Union Carbide) 20 parts Molecular weight Mn19000 Colorless fine particles (silica) 5 parts (Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) Methyl ethyl ketone 67 parts (magenta) Ink) Carmine 6B 9 parts PVC resin (Union Carbide: VMCC) 20 parts Molecular weight Mn19000 Colorless fine particles (silica) 5 parts (Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) Methyl ethyl ketone 67 parts (yellow ink) Disazo Yellow 9 parts PVC resin (Union Carbide: VMCC) 20 parts Molecular weight Mn19000 Colorless fine particles (silica) 5 parts (Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) Methyl ethyl ketone 67 parts

The image obtained in the second embodiment is the same as that in the first embodiment.
In addition to having the same image performance, in the alcohol resistance test (water / ethanol = 1/1, immersion for 12 hours)
Especially excellent.

<Example 3> As an ink composition for a thermal transfer recording layer in Example 1, the following black ink was added to three colors of cyan, magenta and yellow to form a color image composed of four primary colors. (Black ink) Carbon black 9 parts PVC resin (VROH, manufactured by Union Carbide Co., Ltd.) 20 parts Molecular weight Mn15000 Colorless fine particles (silica) 4 parts (Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) Methyl ethyl ketone 67 parts

<Embodiment 4> The color image in the above-described Embodiment 3 was created with three colors of cyan, magenta and yellow, and the binary image of the character and bar code was created with black.

Example 5 Using the thermal transfer recording medium obtained in Example 1, an image was formed on the following image receiving sheet. (Construction of Image Receiving Sheet) Each of the following prescription inks was sequentially applied to a 25 μm polyester film (saturated polyester film; polyethylene terephthalate film) and dried to obtain an image receiving sheet in which a release layer and an image receiving layer were sequentially laminated. (Ink for release layer) Acrylic resin ... 20 parts Methyl ethyl ketone ... 40 parts Toluene ... 40 parts (Ink for image receiving layer) Vinyl chloride vinegar resin (manufactured by Union Carbide: VMCC) ... 20 parts Molecular weight Mn19000 Methyl ethyl ketone ... 70 parts

The image-receiving sheet on which an image was formed in Example 5 was superimposed on a sheet for a final product, and heat transfer was performed from the back of the image-receiving sheet onto the sheet for the final product by a heat roller to obtain a polyester film (polyethylene terephthalate film). ) Alone, a good transfer body having a release layer on the surface which also serves as a protective layer was obtained.

Example 6 Using the thermal transfer recording medium obtained in Example 1, an image was formed on the following image receiving sheet. (Image receiving sheet configuration) The following release layer ink and hologram formation layer ink were sequentially applied to a 25 μm polyester film (saturated polyester film; polyethylene terephthalate film) and dried to obtain a release layer and a hologram formation layer. A hologram was formed on the surface of the hologram-forming layer by heat embossing using an uneven shape. (Ink for release layer) Acrylic resin ... 20 parts Methyl ethyl ketone ... 40 parts Toluene ... 40 parts (Ink for hologram forming layer) Vinyl chloride-vinyl acetate copolymer ... 20 parts Urethane resin ... 15 parts Methyl ethyl ketone ... 70 parts Toluene ... 30 parts

Further, ZnS was provided as a transparent thin film layer on the surface of the hologram forming layer by vapor deposition, and then the following ink for an image receiving layer was applied and dried to laminate the image receiving layer to obtain an image receiving sheet. (Ink for image receiving layer) PVC vinyl chloride resin (manufactured by Union Carbide: VMCC) 20 parts Molecular weight Mn19000 Urethane resin 10 parts Methyl ethyl ketone 70 parts

The image receiving sheet on which the image was formed in Example 6 was superimposed on a sheet for a final product having an ultraviolet light-emitting fluorescent agent printed on the surface, and was placed on the sheet for the final product by a heat roller from the back of the image receiving sheet. When thermal transfer was performed and only the polyester film (polyethylene terephthalate film) was peeled off, a good transfer body having a surface provided with a release layer also serving as a protective layer could be obtained. The obtained transfer body had a hologram image as a security function and had high security.

Comparative Example 1 The following sublimation transfer type ink composition was prepared as an ink for a thermal transfer recording layer. (Cyan ink) C.I. I. Solvent Blue 63: 5 parts Butyral resin (BX-1 manufactured by Sekisui Chemical Co., Ltd.): 5 parts Methyl ethyl ketone: 60 parts Toluene: 30 parts (magenta ink) I. Disperse Red 60: 5 parts Butyral resin (BX-1 manufactured by Sekisui Chemical Co., Ltd.): 5 parts Methyl ethyl ketone: 60 parts Toluene: 30 parts (yellow ink) I. Disperse Yellow 201 5 parts Butyral resin (BX-1 manufactured by Sekisui Chemical Co., Ltd.) 5 parts Methyl ethyl ketone 60 parts Toluene 30 parts

The ink for a thermal transfer recording layer having the above formulation was applied to a 5.4 μm-thick polyethylene terephthalate film having a heat-treated back surface and dried so as to have a dry film thickness of 1.0 μm. Sublimation transfer type thermal transfer recording medium was obtained.

Next, the following ink for a dye-receiving layer was applied to the easy-adhesion surface of a 100-μm easily-adhesive polyester film (saturated polyester film; polyethylene terephthalate film) so as to have a dry film thickness of 4 μm, followed by drying. Aging was performed at 45 ° C. for one week to obtain an image receiving sheet. (Ink for dye receiving layer) Acetal resin ... 10 parts Vinyl chloride-vinyl acetate copolymer resin ... 10 parts Silicone oil ... 2 parts Isocyanate resin ... 3 parts Methyl ethyl ketone ... 50 parts Toluene ... 25 parts

The surface of the thermal transfer recording layer of the obtained thermal transfer recording medium was superimposed on the surface of the dye receiving layer of the image receiving sheet, and an image was formed in the order of yellow, magenta and cyan using a thermal head to obtain a color image by sublimation transfer. .

Comparative Example 2 A thermal transfer recording medium was produced in the same manner as in Example 1 except that the dry film thickness of the ink for the thermal transfer recording layer in Example 1 was changed to 1.2 μm for each of cyan, magenta and yellow. Thus, a color image was formed.

Comparative Example 3 A thermal transfer recording medium was prepared and a color image was formed in the same manner as in Example 1 except that the ink for the thermal transfer recording layer in Example 1 was changed to the following formulation. (Cyan ink) Phthalocyanine blue 9 parts PVC resin (Union Carbide: VROH) 20 parts Molecular weight Mn15000 Methyl ethyl ketone 71 parts (Magenta Ink) Carmine 6B 9 parts PVC resin (Union Carbide: VROH) 20 parts Molecular weight Mn 15000 Methyl ethyl ketone 71 parts (yellow ink) Disazo Yellow 9 parts Vinyl chloride vinegar resin (VROH, manufactured by Union Carbide Co., Ltd.) 20 parts Molecular weight Mn 15000 Methyl ethyl ketone 71 parts

Comparative Example 4 A thermal transfer recording medium was prepared and a color image was formed in the same manner as in Example 1 except that the ink for the thermal transfer recording layer in Example 1 was changed to the following formulation. (Cyan ink) Phthalocyanine blue 9 parts PVC resin (VAGH, manufactured by Union Carbide Co., Ltd.) 20 parts Molecular weight Mn27000 Colorless fine particles (silica) 4 parts (Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) Methyl ethyl ketone 67 parts (magenta) Ink) Carmine 6B 9 parts PVC resin (Union Carbide: VAGH) 20 parts Molecular weight Mn27000 Colorless fine particles (silica) 4 parts (Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) Methyl ethyl ketone 67 parts (yellow ink) Disazo Yellow 9 parts PVC resin (VAGH, manufactured by Union Carbide Co., Ltd.) 20 parts Molecular weight Mn27000 Colorless fine particles (silica) 4 parts (Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) Methyl ethyl ketone 67 parts

Comparative Example 5 A thermal transfer recording medium was prepared and a color image was formed in the same manner as in Example 1 except that the ink for the thermal transfer recording layer in Example 1 was changed to the following formulation. (Cyan ink) Phthalocyanine blue ... 9 parts PVC resin (VYES-4 manufactured by Union Carbide) ... 20 parts Molecular weight Mn5500 Colorless fine particles (silica) ... 4 parts (Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) Methyl ethyl ketone ... 67 parts (Magenta ink) Carmine 6B 9 parts PVC resin (VYES-4 manufactured by Union Carbide) 20 parts Molecular weight Mn5500 Colorless fine particles (silica) 4 parts (Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) Methyl ethyl ketone 67 parts (Yellow Ink) Disazo Yellow 9 parts PVC resin (VYES-4 manufactured by Union Carbide) 20 parts Molecular weight Mn5500 Colorless fine particles (silica) 4 parts (Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) Methyl ethyl ketone 67 parts

Comparative Example 6 A thermal transfer recording medium was prepared and a color image was formed in the same manner as in Example 1 except that the ink for the thermal transfer recording layer in Example 1 was changed to the following formulation. (Cyan ink) Phthalocyanine blue 4 parts PVC resin (VROH, manufactured by Union Carbide Co., Ltd.) 20 parts Molecular weight Mn 15000 Colorless fine particles (silica) 4 parts (Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) Methyl ethyl ketone 72 parts Ink) Carmine 6B 4 parts PVC resin (VROH, manufactured by Union Carbide) 20 parts Molecular weight Mn 15000 Colorless fine particles (silica) 4 parts (Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) Methyl ethyl ketone 72 parts (yellow ink) Disazo Yellow 4 parts PVC resin (VROH, manufactured by Union Carbide Co., Ltd.) 20 parts Molecular weight Mn 15000 Colorless fine particles (silica) 4 parts (Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) Methyl ethyl ketone 72 parts

Comparative Example 7 A thermal transfer recording medium was produced and a color image was formed in the same manner as in Example 1 except that the ink for the thermal transfer recording layer in Example 1 was changed to the following formulation. (Cyan ink) Phthalocyanine blue ... 15 parts PVC resin (VROH, manufactured by Union Carbide) ... 20 parts Molecular weight Mn15000 Colorless fine particles (silica) ... 4 parts (Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) Ink) Carmine 6B 15 parts PVC resin (VROH manufactured by Union Carbide) 20 parts Molecular weight Mn 15000 Colorless fine particles (silica) 4 parts (Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) Methyl ethyl ketone 61 parts (yellow ink) Disazo Yellow 15 parts PVC resin (VROH, manufactured by Union Carbide Co., Ltd.) 20 parts Molecular weight Mn 15000 Colorless fine particles (silica) 4 parts (Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) Methyl ethyl ketone 61 parts

<Comparative Results> Example 1 and Comparative Examples 1, 2,
The images obtained in 3, 4, 5, 6, and 7 were evaluated for image gradation, image density, light fastness, and fixability.

[0071]

[Table 1]

As shown in Table 1, Example 1 according to the present invention was used.
In the thermal recording medium obtained by the above, a color image produced in gradation reproducibility is faithfully reproduced from a highlight portion to a shadow portion, and an excellent thermal transfer recording medium having durability of an image after recording can be obtained. In particular, the heat transfer recording layer had good foil breakability during thermal transfer and high optical density of the transferred image, which was satisfied at the same time, thereby achieving the object of the present invention.

Further, Embodiments 2, 3, 4,
With respect to 5, 6, and 7, the following results were obtained.

That is, the image obtained in Example 2 has the same image performance as that of Example 1, and in the alcohol resistance test (water / ethanol = 1/1, immersion for 12 hours)
Especially excellent. Alcohol resistance test evaluation result In the case of Example 1 ... Acceptable: The level at which the image did not peel off In the case of Example 2 ... Excellent: The level at which there was no change in image and image quality

Further, it was confirmed that the image obtained in Example 3 of the present invention had the same performance as in Example 1.

Further, it was confirmed that the image obtained in Example 4 of the present invention had excellent performance in character and barcode portions in addition to the performance of Example 1 described above.

Further, the image obtained in Example 5 according to the present invention was able to obtain a good transfer body having on its surface a release layer also serving as a protective layer.

Further, from the image obtained in Example 6 according to the present invention, a good transfer body provided with a protective layer on the surface can be obtained, and the obtained transfer body has a hologram image as a security function. And high security.

[0079]

According to the thermal transfer recording medium and the image forming method of 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 to an image receiving sheet by a thermal head printer. It is possible to provide a thermal transfer recording medium capable of forming an image with excellent tone reproducibility by area tone, and furthermore, it has an advantage of preserving the transferred image, especially light fastness and mechanical strength. An object of the present invention is to provide an excellent thermal transfer recording medium.

[Brief description of the drawings]

FIG. 1 is a sectional view of a thermal transfer sheet of the present invention.

FIG. 2 is a cross-sectional view of the thermal transfer sheet of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Thermal transfer recording medium 2 ... Support 3 ... Thermal transfer recording layer
4… Back coat layer

 ────────────────────────────────────────────────── ─── Continued on the front page F-term (reference) 2H111 AA05 AA12 AA26 AA27 AA48 BA03 BA14 BA47 BA48 BA49 BA50 BA53 BA55 BA76 BA78 CA03 CA12 CA44

Claims (8)

[Claims] 1. A thermal transfer recording medium comprising a support having thereon a thermal transfer recording layer formed from a composition containing at least a color pigment, an organic resin binder, and colorless or pale-colored fine particles as main components. The layer has a thickness of 0.5-1.
A thermal transfer recording medium, wherein the organic resin binder is a vinyl chloride-vinyl acetate copolymer resin having an average molecular weight of 10,000 to 20,000 in a range of 0 μm. 2. A composition according to claim 1, wherein said composition for forming a thermal transfer recording layer comprises a color pigment of 20 to 30 parts by weight based on 100 parts by weight of the total solid content.
2. The thermal transfer recording medium according to claim 1, wherein the composition has a composition of 1 part by weight, 40 to 70 parts by weight of polyvinyl chloride resin, and 1 to 30 parts by weight of colorless or light-colored fine particles. 3. A vinyl chloride-vinyl acetate-maleic acid copolymer resin containing 1 to 5% by weight of maleic acid as a copolymer component of said vinyl chloride-vinyl acetate copolymer resin. The thermal transfer recording medium according to claim 1. 4. The method according to claim 1, wherein the color pigment has an average particle size of 50 to 500.
4. The thermal transfer recording medium according to claim 1, wherein the thermal transfer recording medium is in a range of nm. 5. The colorless or light-colored fine particles have an average particle size of 10 to 300 nm and are smaller than the average particle size of the color pigment. 2. The thermal transfer recording medium according to claim 1. 6. The method according to claim 1, wherein the colorless or light-colored fine particles are silica.
Item 6. The thermal transfer recording medium according to Item 1. 7. The thermal transfer recording layer is provided with three colors of cyan, magenta, and yellow, or four colors of black, cyan, magenta, and yellow, which are repeatedly arranged in a proper order along the longitudinal direction on the support. The thermal transfer recording medium according to any one of claims 1 to 6, wherein: 8. An image forming method, wherein the thermal transfer recording layer of the thermal transfer recording medium according to claim 1 is thermally transferred onto an image receiving sheet using a thermal head printer to form an image by area gradation. An image forming method, comprising thermally transferring an image-receiving layer having a vinyl chloride-vinyl acetate copolymer resin as a main component onto the image-receiving layer of an image-receiving sheet having a coating formed thereon.