JP3384377B2 - Thermal transfer recording medium and image forming method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer recording layer containing a color pigment, which is thermally transferred onto an image-receiving sheet by a thermal head printer, and more specifically, at least two or more colors are superposed to produce a gradation by area gradation. The present invention relates to a thermal transfer recording medium for forming a color image and the like and an image forming method.

[0002]

2. Description of the Related Art Conventionally, a sublimation transfer method and a melt transfer method are known as a thermal transfer recording method for forming a gradation image using a thermal head printer. Sublimation transfer method,
A thermal transfer recording medium having a thermal transfer recording layer consisting of a sublimable (heat transferable) dye and a binder resin is placed on an image receiving sheet, and the sublimation dye in the thermal transfer recording layer is imaged according to the amount of heat of the thermal head. The image is transferred onto a sheet to form a gradation image.

However, when an image is formed using such a sublimable (heat transferable) dye, the formed image is inferior in durability and its use in fields requiring heat resistance and light resistance is limited. It In addition, since the thermal recording sensitivity is lower than that of the melt transfer method, it is not suitable as a high-speed recording material using a high resolution thermal head that is expected to be put to practical use in the future because it is smaller and lighter in the printer driven by batteries such as dry batteries. have.

On the other hand, in the melt transfer method, a transfer sheet having a heat-fusible ink transfer layer composed of a coloring material such as a pigment or a dye and a binder such as a wax on a support is used to heat a thermal head or the like. This is a system in which energy is applied to the device according to image information and the ink transfer layer is fused on the image receiving sheet to form an image. The image formed by the melt transfer method has high density and excellent sharpness, and is suitable for recording binary images such as characters and line drawings. Further, by using a thermal transfer sheet composed of yellow, magenta, cyan, and black to form an image by superimposing it on the image receiving sheet,
It is also possible to form a color image. Japanese Patent Publication No. 63-65029 discloses such a thermal transfer sheet for forming a color image.

[0005]

However, in the case of the thermal transfer sheet described in JP-B-63-65029,
Since a crystalline wax having a low melting point is used as a binder for the ink layer, the resolution of the ink is likely to decrease due to the blurring of the ink. Further, the fixing strength of the transferred image is weak, and if the image portion is rubbed hard with the hand, the image portion will be removed. Various proposals have been made as methods for solving such a phenomenon.

For example, Japanese Patent Application Laid-Open No. 61-244592 proposes a heat-sensitive transfer sheet having a heat-sensitive ink layer comprising 65% or more of an amorphous polymer, a releasing material and a colorant. However, the above-mentioned Japanese Unexamined Patent Publication No. 61-24459.
The thermal transfer sheet described in Japanese Patent Publication No. 2 also contains a crystalline wax, so that the fixing strength of the portion where the overprinting of each color is performed is insufficient.

The present invention has been made in view of the above-mentioned problems of the prior art, and reduces the resolution due to ink bleeding due to the use of a crystalline wax having a low melting point as a binder for an ink layer. Preventing it, and when using a wax, the durability is insufficient when the transferred image is rubbed by hand, improving the point that the image is easily removed and increasing the durability, and especially, An object of the present invention is to provide a thermal transfer recording medium (thermosensitive transfer ribbon) which has good foil breakability of the thermal transfer recording layer at the time of thermal transfer and has a high optical density of a transferred image, and at the same time can sufficiently achieve these. .

[0008]

As a result of intensive studies, the present inventors have made it possible to solve the above-mentioned problems by using a melt transfer method. That is, in the invention according to claim 1, the main component is a color pigment, an epoxy resin, and silica , which is colorless or light-colored fine particles , on the support, and the film thickness is 0.
A thermal transfer recording layer in the range of 5 to 1.0 μm is provided, the softening point of the epoxy resin is in the range of 70 to 150 ° C., and the color pigment is 20 to 3 in the thermal transfer recording layer.
The thermal transfer recording medium is characterized by being contained in an amount of 0 % by mass.

The invention according to claim 2 is the thermal transfer recording medium according to claim 1, wherein the color pigment has an average particle diameter in the range of 50 to 500 nm.

According to the third aspect of the invention, the composition forming the thermal transfer recording layer contains no coloring pigment and epoxy resin.
Total amount of silica, which is fine particles of color or light color, 100 % by mass
Respect, the coloring pigment is 20 to 30 wt%, epoxy resin is 40 to 70 wt%, colorless or light-colored fine particles Siri
Ca is a thermal transfer recording medium according to claim 1 or 2, characterized in that the blending composition of 1 to 30 wt%.

The invention according to claim 4 is characterized in that the fine particles of colorless or light-colored silica in the thermal transfer recording layer have an average particle diameter in the range of 100 to 300 nm. The thermal transfer recording medium according to any one of 1.

[0012]

The invention according to claim 5 relates to the heat transfer.
Three colors of cyan, magenta and yellow as the recording layer
Or, alternatively, black, cyan, claims 1 to 4 four colors magenta and yellow, characterized in that on the support is provided a surface sequentially arranged repeatedly along the longitudinal direction
The thermal transfer recording medium according to any one of 1.

[0014] In the invention according to claim 6, using a thermal head printer and a thermal transfer thermal transfer recording layer of claims 1 to 5, wherein the thermal transfer recording medium onto the image receiving sheet, an image is formed by an area gradation In the image forming method, an epoxy resin is formed by coating on the surface of the image receiving sheet.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The principle of transfer of a thermal transfer recording medium of the present invention is that heat is applied to a thermal transfer recording material by a thermal medium such as a thermal head, at which time the acrylic resin in the thermal transfer recording layer is thermally melted. Rather, it becomes a softened or semi-molten state, the adhesiveness to the image receiving layer is developed and the adhesiveness to the medium substrate is reduced at the same time, and the image is recorded by adhering the thermal transfer recording layer on the image receiving sheet. To be done. This transfer principle is considered to be related to the fact that the thickness of the film of the thermal transfer recording layer is very thin as described above, and is also called a thermal adhesive thin film peeling method rather than the traditional so-called thermal fusion transfer. It is considered to be a transcription belonging to a power type. Regarding the term of the thermal adhesive thin film peeling method, Japanese Patent Laid-Open No. 7-1
See Japanese Patent No. 17359. As a result, when printing is performed by superimposing at least two colors, clear printing can be obtained without ink bleeding. In addition, the transferred recorded image is excellent in mechanical strength, and is also excellent in halftone expression by dot area gradation.

The thermal transfer recording medium of the present invention will be described in detail below. 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).

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

The epoxy resin contained in the thermal transfer recording layer (3) has a softening point in the range of 70 ° C. to 150 ° C. in consideration of printability on a thermal medium such as a thermal head and durability of the image after transfer recording. Use one.

The thermal condition for thermal transfer using a thermal head is usually 300 to 400 ° C. for several milliseconds, and when this is converted into a static condition, it is 100 to 150 ° C. for 5 seconds. Further, as described above, in order to perform thermal transfer recording, it is necessary to heat the epoxy resin until it is dissolved. Therefore, considering the amount of heat supplied from the thermal head and the melting state of the epoxy resin, the upper limit of the melting point is 150 ° C. If a resin having an amount higher than this upper limit is used, more energy is required for transfer, and the life of the thermal head becomes extremely short. The lower limit of 70 ° C. is set in consideration of the stability of image retention after transfer recording. When an epoxy resin having a melting point of 70 ° C. or less is used, tailing may occur when rubbed by hand. The phenomenon occurs.

As a characteristic of the epoxy resin used as a main material in the thermal transfer recording layer of the present invention, it is particularly preferable that the epoxy equivalent (the number of grams of the resin containing 1 gram of epoxy group) is 600 to 5,000. It has an average molecular weight of 800 to 5,000. If the epoxy equivalent of this epoxy resin is lower than the lower limit value (less than 600), the durability of the image against rubbing is not sufficient, and rubbing with a hand tends to cause tailing of the transferred image, which is not preferable. . On the contrary, if the epoxy equivalent is higher than the upper limit value (more than 5,000), the thermal energy required for thermal transfer is too large,
Since the life of the thermal head is shortened and the sensitivity of thermal transfer is low, it is unsuitable for applications in which thermal transfer recording of images at high speed is unsuitable.

If the weight average molecular weight of this epoxy resin is lower than the lower limit value (less than 800), the durability of the image against rubbing is not sufficient, and the transferred image is tailed when rubbed by hand. It is not preferable because it easily occurs.
On the other hand, if the molecular weight is higher than the upper limit (greater than 5,000), the thermal energy required for thermal transfer is too large, which shortens the life of the thermal head. However, the sensitivity of the heat-sensitive transfer is low, and it is not suitable for the purpose of the heat-sensitive transfer recording of an image at a high speed, which is not preferable.

The most preferable epoxy resin in the present invention is a case where all the characteristics of softening point, epoxy equivalent and molecular weight are simultaneously within the respective ranges.

For the above reasons, the melting point is 70 to 150 ° C., the epoxy equivalent is 600 to 5000, and the molecular weight is 800 to
An epoxy resin in the range of 5000 is selected. Examples of such an epoxy resin include bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, resorcinol diglycidyl ether, cresol novolac polyglycidyl ether, and tetrabromobisphenol A. Glycidyl ether type epoxy resin such as diglycidyl ether, bisphenol hexafluoroacetone glycidyl ether, phthalic acid diglycidyl ester, glycidyl ester type epoxy resin such as dimer acid diglycidyl ester, triglycidyl isocyanurate, tetraglycidyl aminodiphenylmethane, tetraglycidyl Glycidylamine type epoxy resin such as metaximendiamine, and hexahydrobisphenol A diglycol Jill ether, polypropylene glycol diglycidyl ether, aliphatic epoxy resins such as neopentyl glycol diglycidyl ether.

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

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 % by mass. More preferably, the color pigment has an average particle diameter of 50 to 500.
in the nm range.

If the ratio of the color pigment contained in the thermal transfer recording layer is less than the lower limit value (20 % by mass), it is difficult to obtain a sufficient optical density of the transferred image, which is not preferable. On the other hand, if this ratio exceeds the upper limit (30 % by mass), the adhesive force to the image receiving layer side is too weak during heat-sensitive transfer, so that the fixability particularly at the overlapping portion of the color deteriorates. , The durability of the image is poor.

Further, if the average particle diameter of the color pigment contained in the thermal transfer recording layer is less than the lower limit value (50).
(less than 1 nm), the foil breakage of the thermal transfer recording layer is deteriorated, and more specifically, the dot shape on which the transferred image is formed and the gradation reproducibility are deteriorated, which is not preferable. On the other hand, if the average particle diameter exceeds the upper limit value (exceeds 500 nm), the color developability of the pigment is lowered and it is difficult to obtain a sufficient optical density of the transferred image, which is not preferable.

The average particle diameter referred to here is a measurement in a coating liquid state in which the thermal transfer recording layer is formed, and since the particle diameters after forming the thermal transfer recording layer are almost the same, the average particle diameter in the coating liquid state is Can be set as appropriate. The measurement method is AUTOSI made by MARVERUN by the light scattering method.
It can be easily measured by ZER2C.

The colorless or light-colored fine particles contained in the thermal transfer recording layer (3) are used to improve transferability during thermal transfer, more specifically, dot shape on which a transferred image is formed, and gradation reproducibility. The use of colorless or light-colored components as necessary components is to prevent the coloring of a colored image formed by thermal transfer from being impaired as much as possible. Examples of such colorless or light-colored fine particles include silica, calcium carbonate, kaolin, clay, starch, zinc oxide, Teflon powder, polyethylene powder, polymethylmethacrylate resin beads, polyurethane resin beads, benzoguanamine and melamine resin beads. Can be mentioned. Of the above, silica fine particles are particularly preferable.

Further, the size of the colorless or light-colored fine particles in the present invention is preferably such that the average particle size is in the range of 100 to 300 nm. If the average particle size of the fine particles is less than 100 nm, the foil breakage of the thermal transfer recording layer becomes worse, and more specifically, the dot shape on which the transfer image is formed and the gradation reproducibility are deteriorated, which is preferable. Absent. On the other hand, if the average particle size is more than 300 nm, it is not preferable because the coloring of the colored image formed by thermal transfer is impaired.

It is more preferable that the particle size distribution of the fine particles has a narrower spread than that of the color pigment. When there is this relationship in the particle size distribution between the fine particles and the color pigment, without impairing the color developability of the pigment,
Foil breakage of the thermal transfer recording layer is good, and more specifically, dot shape on which a transfer image is formed, gradation reproducibility, and the like are very good. The cause is still unclear, but its effect is high. As a typical example of capturing the width of the spread, there is a method of evaluation based on a half width.

The composition of the composition for forming the thermal transfer recording layer (3) is such that the total amount of the color pigment and the epoxy resin is 100.
Relative to the mass%, the coloring pigment is 20 to 30 wt%, epoxy resin 40 to 70 wt%, colorless or light-colored fine particles 1
Is about 30 % by mass. If the epoxy resin is less than the above range, it is not preferable in that the film strength is lowered,
On the contrary, when the amount is large, the transferability, more specifically, the dot shape on which the transfer image is formed, the gradation reproducibility, and the like are deteriorated, which is not preferable.

When the amount of colorless or light-colored fine particles is less than the above range, the transferability, more specifically, the dot shape on which the transferred image is formed, and the gradation reproducibility are deteriorated, which is not preferable. If the amount is large, good ink fluidity cannot be obtained, which is not preferable. It should be noted that various additives may be added to this, if necessary. The addition amount thereof is preferably 10 % by mass or less based on 100 % by mass of the composition for forming the thermal transfer recording layer.

The method for producing a thermal transfer recording medium of the present invention comprises bar coating a composition prepared by dispersing or dissolving a colorant, an epoxy resin and colorless fine particles in a solvent on a substrate such as coated paper or plastic. The thermal transfer recording layer is formed by applying by a solvent coating method such as blade coating, air knife coating, gravure coating, or roll coating, and drying.

The film thickness of the thermal transfer recording layer (3) is 0.5 to
1.0 μm is desirable. If the film thickness is less than 0.5 μm, it is difficult to obtain a sufficient density, and if it exceeds 1.0 μm, it becomes difficult to transfer in accordance with the heat generating portion of the thermal head. The gradation reproducibility and the like are inferior. Further, heat is applied from the side of the support (2) on which the thermal transfer recording layer (3) is not provided by using a thermal head, and the thermal transfer recording layer (3) is placed on the image receiving sheet.
In order to prevent the thermal head from adhering to the support (2) and hindering the smooth running property of the thermal transfer recording medium (1) during transfer, the thermal transfer recording layer (3) of the support (2)
It is desirable to provide the back coat layer (4) on the side where no is provided.

Examples of the material used for such a back coat layer (4) include nitrocellulose, polyester resin, acrylic resin, vinyl resin and the like containing silicone oil, or silicone modified resin. it can. Further, a crosslinking agent may be used in combination for the purpose of improving heat resistance. The coating thickness when the back coat layer (4) is provided is preferably about 0.1 to 4 μm.

An image receiving sheet used for forming an image using the thermal transfer recording medium (1) as described above is
Papers such as high-quality papers and coated papers, plastic films such as polyester films, polyvinyl chloride films and polypropylene films, or papers and plastic films coated with an image receiving layer may be mentioned.
The image receiving layer used here is preferably an epoxy resin. That is, by using the epoxy resin as the image receiving layer, the thermal transfer recording layer and the image receiving layer are well adhered by the heat at the time of thermal transfer even if the thermal transfer recording layer of the thermal transfer recording medium is not sufficiently melted at the time of thermal transfer. Since printing is performed by cutting a foil, transferability, more specifically, dot shape on which a transfer image is formed, gradation reproducibility, and the like are improved. Further, the formed image has excellent image resistance such as abrasion resistance and scratch resistance.

When it is difficult to form an image directly on the sheet on which an image is to be formed, the image may be formed once on the image receiving sheet and then the transferred image may be retransferred onto the final sheet. . In such an indirect transfer method, not only the selectivity of the final sheet is widened, but also by providing a protective layer on the image receiving sheet, a protective layer is provided on the final transferred image to improve the image resistance and By providing a security layer such as a hologram forming layer on the sheet, the security of the final transferred image can be improved.

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

[0040]

EXAMPLES Next, the present invention will be described more specifically with reference to examples. In the text, “part” or “%” is based on mass unless otherwise specified.

Example 1 First, an ink composition for a thermal transfer recording layer having the following composition was prepared.

[0042] (Cyan ink)   Phthalocyanine blue ... 9 parts   Epoxy resin (Okaka Shell Epoxy Co., Ltd .: Epicoat 1007) ... 20 parts     * Softening point 128 ° C Epoxy equivalent 1750-2200 Molecular weight 2900   Colorless fine particles (silica: Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) ... 4 parts   Methyl ethyl ketone ... 67 parts

[0043] (Magenta ink)   Carmine 6B ... 9 copies   Epoxy resin (Okaka 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

[0044] (Yellow ink)   Disazo Yellow ... 9 copies   Epoxy resin (Okaka 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

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

Next, the following image-receiving layer ink was applied to the easily-adhesive surface of a 100 μm easily-adhesive polyester film so as to have a dry film thickness of 5 μm and dried to obtain an image-receiving sheet.

[0047] (Image-receiving layer ink)   Epoxy resin (Okaka Shell Epoxy Co., Ltd .: Epicoat 1007) ... 30 parts     * Softening point 128 ° C Epoxy equivalent 1750-2200 Molecular weight 2900   Methyl ethyl ketone ... 70 parts

The surface of the thermal transfer recording layer of the obtained cyan thermal transfer recording medium and the image receiving sheet were superposed, and a thermal head was used to obtain a cyan image with an area gradation corresponding to the heating portion of the thermal head. Next, using a magenta thermal transfer recording medium, a magenta image by area gradation was formed on an image receiving sheet on which a cyan image was formed in the same manner as for cyan.
In the same manner, a yellow image was formed, and a color image consisting of area gradation alone could be formed on the image receiving sheet.

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

[0050] (Magenta ink)   C. I. Disperse Red 60 ... 5 copies   Butyral resin (BX-1 manufactured by Sekisui Chemical Co., Ltd.) ... 5 parts   Methyl ethyl ketone ... 60 parts   Toluene ... 30 parts

[0051] (Yellow ink)   C. I. Disperse Yellow 201 ... 5 copies   Butyral resin (BX-1 manufactured by Sekisui Chemical Co., Ltd.) ... 5 parts   Methyl ethyl ketone ... 60 parts   Toluene ... 30 parts

Comparative Example 1 was prepared by applying the ink for the thermal transfer recording layer having the above formulation to a polyethylene terephthalate film having a thickness of 5.4 μm and having a heat-treated back surface so that the dry film thickness was 1.0 μm. A thermal transfer recording medium of was obtained.

Next, the following dye-receiving layer ink was applied to the easy-adhesion surface of the 100 μm easily-adhesive polyester film so that the dry film thickness was 4 μm, and dried, and then 45
Aging was carried out at ℃ for 1 week to obtain an image receiving sheet.

[0054] (Ink for dye receiving layer)   Acetal resin: 10 parts   Vinyl chloride-vinyl acetate copolymer resin: 10 parts   Silicon 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 and the surface of the dye receiving layer of the image receiving sheet were superposed, and images were formed in order of yellow, magenta and cyan using a thermal head to obtain a color image.

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

(Comparative Example 3) Example 1 is the same as Example 1 except that the ink for the thermal transfer recording layer is changed to the following formulation.
A thermal transfer recording medium was prepared in the same manner as in 1. to form a color image.

[0058] (Cyan ink)   Phthalocyanine blue ... 9 parts   Epoxy resin (Okaka Shell Epoxy Co., Ltd .: Epicoat 1007) ... 20 parts     * Softening point 128 ° C Epoxy equivalent 1750-2200 Molecular weight 2900   Methyl ethyl ketone ... 71 parts

[0059] (Magenta ink)   Carmine 6B ... 9 copies   Epoxy resin (Okaka Shell Epoxy Co., Ltd .: Epicoat 1007) ... 20 parts     * Softening point 128 ° C Epoxy equivalent 1750-2200 Molecular weight 2900   Methyl ethyl ketone ... 71 parts

[0060] (Yellow ink)   Disazo Yellow ... 9 copies   Epoxy resin (Okaka Shell Epoxy Co., Ltd .: Epicoat 1007) ... 20 parts     * Softening point 128 ° C Epoxy equivalent 1750-2200 Molecular weight 2900   Methyl ethyl ketone ... 71 parts   Phthalocyanine blue ... 10 parts

Comparative Example 4 Example 1 was repeated except that the ink for the thermal transfer recording layer was changed to the following formulation.
A thermal transfer recording medium was prepared in the same manner as in 1. to form a color image.

[0062] (Cyan ink)   Phthalocyanine blue ... 9 parts   Epoxy resin (Okaka Shell Epoxy Co., Ltd .: Epicoat 1001) ... 20 parts     * Softening point 64 ° C Epoxy equivalent 450-500 Molecular weight 900   Colorless fine particles (silica: Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) ... 4 parts   Methyl ethyl ketone ... 67 parts

[0063] (Magenta ink)   Carmine 6B ... 9 copies   Epoxy resin (Okaka Shell Epoxy Co., Ltd .: Epicoat 1001) ... 20 parts     * Softening point 64 ° C Epoxy equivalent 450-500 Molecular weight 900   Colorless fine particles (silica: Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) ... 4 parts   Methyl ethyl ketone ... 67 parts

[0064] (Yellow ink)   Disazo Yellow ... 9 copies   Epoxy resin (Okaka Shell Epoxy Co., Ltd .: Epicoat 1001) ... 20 parts     * Softening point 64 ° C Epoxy equivalent 450-500 Molecular weight 900   Colorless fine particles (silica: Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) ... 4 parts   Methyl ethyl ketone ... 67 parts

Comparative Example 5 Example 1 was repeated except that the ink for the thermal transfer recording layer was changed to the following formulation.
A thermal transfer recording medium was prepared in the same manner as in 1. to form a color image.

[0066] (Cyan ink)   Phthalocyanine blue ... 9 parts   Epoxy resin (Okaka Shell Epoxy Co., Ltd .: Epicoat 1010) ... 20 parts     * Softening point 169 ° C Epoxy equivalent 3000-5000 Molecular weight 5500   Colorless fine particles (silica: Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) ... 4 parts   Methyl ethyl ketone ... 67 parts

[0067] (Magenta ink)   Carmine 6B ... 9 copies   Epoxy resin (Okaka Shell Epoxy Co., Ltd .: Epicoat 1010) ... 20 parts     * Softening point 169 ° C Epoxy equivalent 3000-5000 Molecular weight 5500   Colorless fine particles (silica: Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) ... 4 parts   Methyl ethyl ketone ... 67 parts

[0068] (Yellow ink)   Disazo Yellow ... 9 copies   Epoxy resin (Okaka Shell Epoxy Co., Ltd .: Epicoat 1010) ... 20 parts     * Softening point 169 ° C Epoxy equivalent 3000-5000 Molecular weight 5500   Colorless fine particles (silica: Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) ... 4 parts   Methyl ethyl ketone ... 67 parts

Comparative Example 6 Example 1 was repeated except that the ink for the thermal transfer recording layer was changed to the following formulation.
A thermal transfer recording medium was prepared in the same manner as in 1. to form a color image.

[0070] (Cyan ink)   Phthalocyanine blue ... 4 parts   Epoxy resin (Okaka 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 ... 72 parts

[0071] (Magenta ink)   Carmine 6B ... 4th   Epoxy resin (Okaka 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 ... 72 parts

[0072] (Yellow ink)   Disazo yellow ... 4 parts   Epoxy resin (Okaka 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 ... 72 parts

Comparative Example 7 Example 1 was repeated except that the ink for the thermal transfer recording layer was changed to the following formulation.
A thermal transfer recording medium was prepared in the same manner as in 1. to form a color image.

[0074] (Cyan ink)   Phthalocyanine blue ... 15 parts   Epoxy resin (Okaka 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 ... 61 parts

[0075] (Magenta ink)   Carmine 6B ... 15 copies   Epoxy resin (Okaka 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 ... 61 parts

[0076] (Yellow ink)   Disazo Yellow ... 15 copies   Epoxy resin (Okaka 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 ... 61 parts

The images obtained in Example 1 and Comparative Examples 1, 2, 3, 4, and 5 were evaluated for image gradation, light resistance, and fixability.

[0078] Image Gradation ………… ○: The produced color image is from the highlight part to the shadow part                     Faithfully reproduced                 X: Insufficient reproducibility from the highlight part to the shadow part                     It Image density ………… ○: Color reflection density is 1.4 or more                 X: Color reflection density is 1.4 or less Light resistance ……………… A xenon fade meter illuminates the color image surface for 80 hours.                 Shoot and measure the fading rate.                 ○: fading rate within 5%                 ×: fading rate of 5% or more Fixability ......... Tailing of the image area when the color image surface is rubbed with a nail with normal force                 Degree                 ○: No change                 ×: There is dirt around the image area

As shown in the table, in the thermosensitive recording medium (Example 1) according to the present invention, the color image produced with gradation reproducibility is faithfully reproduced from the highlight portion to the shadow portion,
It is possible to obtain an excellent thermal transfer recording medium having durability of an image after recording, and particularly, the foil transfer property of the thermal transfer recording layer at the time of thermal transfer is good, and the optical density of the transferred image is high. At the same time, the object of the present invention was achieved.

(Example 2) In Example 1, as the ink composition for the thermal transfer recording layer, the following black ink was added to three colors of cyan, magenta and yellow to prepare a color image consisting of four primary colors.

[0081] (Black ink)   Carbon black ... 9 parts   Epoxy resin (Okaka Shell Epoxy Co., Ltd .: Epicoat 1007) ... 20 parts     * Epoxy equivalent 1750 to 2200 Softening point 128 ° C Molecular weight 2900   Colorless fine particles (silica: Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) ... 4 parts   Methyl ethyl ketone ... 67 parts

It was confirmed that the obtained image had the same performance as in Example 1.

(Example 3) In Example 3, a color image was prepared from three colors of cyan, magenta and yellow, and a binarized image of characters and barcodes was prepared in black. It was confirmed that the obtained image has excellent resistance to characters and barcode portions in addition to the performance of Example 1.

Example 4 Using the thermal transfer recording medium obtained in Example 1, an image was formed on the following image receiving sheet.

(Structure of Image Receiving Sheet) Each of the following prescription inks was sequentially coated on a 25 μm polyester film and dried to obtain an image receiving sheet in which a release layer and an image receiving layer were sequentially laminated.

[0086]   (Ink for release layer)   Acrylic resin: 20 parts   Methyl ethyl ketone ... 40 parts   Toluene ... 40 parts

[0087]   (Ink for image receiving layer)   Epoxy resin (Okaka Shell Epoxy Co., Ltd .: Epicoat 1007) ... 30 parts     * Epoxy equivalent 1750 to 2200 Softening point 128 ° C Molecular weight 2900   Methyl ethyl ketone ... 70 parts

The image-formed image-receiving sheet was superposed on the final product sheet and heat-transferred from the back surface of the image-receiving sheet with a heat roller, and only the polyester film was peeled off to obtain a good transfer body having a protective layer on the surface. I was able to get it.

Example 5 Using the thermal transfer recording medium obtained in Example 1, an image was formed on the following image receiving sheet.

(Structure of Image Receiving Sheet) The following peeling layer ink and hologram forming layer ink were sequentially coated on a 25 μm polyester film and dried to obtain a peeling layer and a hologram forming layer, and then the hologram forming layer was formed by heat embossing. A hologram having a concave-convex shape was formed on the surface of the.

[0091]   (Ink for release layer)   Acrylic resin: 20 parts   Methyl ethyl ketone ... 40 parts   Toluene ... 40 parts

[0092]   (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 as a transparent thin film layer was provided on the surface of the hologram forming layer by vapor deposition, and then the following image receiving layer ink was applied and dried to laminate the image receiving layer to obtain an image receiving sheet.

[0094]   (Ink for image receiving layer)   Epoxy resin (Okaka Shell Epoxy Co., Ltd .: Epicoat 1007) ... 20 parts     * Epoxy equivalent 1750 to 2200 Softening point 128 ° C Molecular weight 2900   Urethane resin: 10 parts   Methyl ethyl ketone ... 70 parts

The image-formed image-receiving sheet is superposed on the final product sheet having an ultraviolet-emitting fluorescent agent printed on the surface, and heat transfer is performed from the back surface of the image-receiving sheet with a heat roller.
When only the polyester film was peeled off, a good transfer member having a protective layer on the surface could be obtained. The obtained transfer member had a hologram image as a security function, and had high security.

[0096]

[Table 1]

[0097]

According to the present invention, the thermal transfer recording layer contains a color pigment, a binder resin and colorless fine particles, and the thermal transfer recording layer is thermally transferred onto an image receiving sheet by a thermal head printer to reproduce gradation by area gradation. It is possible to provide a thermal transfer recording medium capable of forming an image having excellent properties, and moreover, to provide a thermal transfer recording medium excellent in storability of an image after transfer, particularly excellent in light resistance and mechanical strength. It is provided.

[Brief description of drawings]

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

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

3 shows the dispersity of the cyan pigment used in Example 1. FIG.
The horizontal axis represents the particle diameter (nm), and the vertical axis represents the ratio (%) of the particles of each particle size.

4 shows the dispersity of the magenta pigment used in Example 1. FIG. The horizontal axis represents the particle diameter (nm), and the vertical axis represents the ratio (%) of the particles of each particle size.

5 shows the dispersity of the yellow pigment used in Example 1. FIG. The horizontal axis represents the particle diameter (nm), and the vertical axis represents the ratio (%) of the particles of each particle size.

6 shows the dispersity of colorless or transparent fine particles used in Example 1. FIG. The horizontal axis represents the particle diameter (nm), and the vertical axis represents the ratio (%) of the particles of each particle size.

[Explanation of symbols]

1 ... Thermal transfer recording medium 2 ... Support 3 ... Thermal transfer recording layer 4 ... Back coat layer

─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-9-99644 (JP, A) JP-A-4-305492 (JP, A) JP-A-63-95988 (JP, A) JP-A-9- 24679 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) B41M 5/38-5/40

Claims (6)

(57) [Claims] 1. A support comprising, as a main component, a color pigment, an epoxy resin, and colorless or light-colored fine particles of silica .
A thermal transfer recording layer having a film thickness in the range of 0.5 to 1.0 μm is provided, the softening point of the epoxy resin is in the range of 70 to 150 ° C., and the color pigment is 20 to 20 in the thermal transfer recording layer. A thermal transfer recording medium characterized by being contained in a range of 30 mass % . 2. The color pigment has an average particle diameter of 50 to 50.
The thermal transfer recording medium according to claim 1, wherein the thermal transfer recording medium is in the range of 0 nm. 3. A composition comprising a thermal transfer recording layer, wherein the composition is a color pigment, an epoxy resin and colorless or light-colored fine particles.
With respect to the total amount of 100 % by mass, the color pigment is 20 to 30
The thermal transfer recording medium according to any one of claims 1 and 2, characterized in that the compounding composition is such that the mass % of the epoxy resin is 40 to 70 % by mass, and the colorless or light-colored fine particles of silica are 1 to 30 % by mass. . 4. The colorless or light color in the thermal transfer recording layer.
The thermal transfer recording medium according to any one of claims 1 to 3, wherein the fine particles of silica have an average particle diameter in the range of 100 to 300 nm. 5. As the thermal transfer recording layer, three colors of cyan, magenta and yellow, or four colors of black, cyan, magenta and yellow are repeatedly provided on a support in a plane-sequential manner along the longitudinal direction. The thermal transfer recording medium according to any one of claims 1 to 4 , wherein With 6. The thermal head printer, to transfer the thermal transfer recording layer of claims 1 to 5, wherein the thermal transfer recording medium onto the image receiving sheet, an image forming method for forming an image by area gradation, image receiving sheet An image forming method, characterized in that an epoxy resin is formed on the surface by coating.