JP2013052638A - Thermal transfer recording medium - Google Patents

Abstract

The present invention provides a thermal transfer recording medium capable of preventing image omission and unevenness during thermal transfer even on an image receiving sheet lacking in smoothness of a receiving layer.
A thermal transfer recording medium for forming an image through heat on a thermal transfer member having at least one linear cross-sectional concave shape having a length L in width, the thermal transfer comprising at least a dye, a binder resin and particles. A thermal transfer recording medium comprising a layer and having a ratio [L / r] of the average particle diameter r of the particles to the length L of the width of 0.5 to 1.5. .
[Selection] Figure 2

Description

  The present invention relates to a thermal transfer recording medium having a thermal transfer layer for forming characters or images on a thermal transfer member.

  Conventionally, a sublimation thermal transfer system, a melt thermal transfer system, or the like has been adopted as a system for forming characters or images on a transfer target. For example, in the case of the sublimation type thermal transfer system, the surface of the thermal transfer recording medium provided with a thermal transfer layer containing a dye or a binder on the support, and a coated layer provided with a receiving layer for receiving the dye on another support. Dye in the thermal transfer layer is sublimated by superimposing the receiving layer surface of the thermal transfer body on each other and heating from the surface of the thermal transfer recording medium where the thermal transfer layer is not provided with a thermal head or the like that is temperature controlled by text or image information. The desired character or image is formed by shifting to the receiving layer.

  On the other hand, in the case of the melt-type thermal transfer system, the thermal transfer layer surface of the thermal transfer recording medium provided with a heat-fusible thermal transfer layer containing a pigment or wax on the support, and the thermal transfer provided with a receiving layer on another support. The receiving layer surface of the body is superposed on each other and heated by a thermal head or the like, so that the thermal transfer layer is fused and transferred to the receiving layer to form a desired character or image. Among the above methods, the sublimation thermal transfer method is widely used for monochrome printing such as characters and charts and color printing such as digital camera images or computer graphics images.

  By the way, in the case of the sublimation type thermal transfer system, when the receiving layer surface is not flat, that is, when the receiving layer surface has irregularities, the thermal transfer recording medium has poor followability to the thermal transfer medium when heated by a thermal head or the like. As a result, the image becomes uneven, causing a problem that the image is missing or uneven.

  In order to solve the above problems, for example, as an improvement measure for a thermal transfer recording medium (thermal transfer ribbon), bubbles are formed in a layer selected from one or more of a dye layer and an intermediate layer constituting the thermal transfer recording medium. It contains cushioning properties, and as a result, even when the surface of the image receiving sheet as a transfer material is inferior in smoothness, it is excellent in dye transfer at the time of thermal transfer and excellent in no white spots etc. A method capable of obtaining an image has been proposed (see Patent Document 1).

  Further, for example, as a measure for improvement in the thermal transfer image receiving sheet, in the thermal transfer image receiving sheet comprising a heat insulating layer containing hollow particles and a binder in the base sheet, and a receiving layer, the base sheet is at least the intermediate paper A method of obtaining a printed matter with less white spots and roughness by setting the bending elastic modulus of the two resin coating layers formed of resins having different bending elastic moduli on the side surface of the heat insulating layer laminated is proposed. (See Patent Document 2). Further, in the thermal transfer image receiving sheet having a porous intermediate layer and an image receiving layer on a substrate, the porous intermediate layer has a porosity of 30% or more and contains at least one inorganic fine particle. In addition, by forming with a coating method, the occurrence of curling at the time of manufacture is suppressed, an image excellent in whiteout resistance is obtained without impairing sensitivity as a printing characteristic, and excellent in sticking resistance even in a high-speed printing printer. A method for obtaining a thermal transfer image-receiving sheet has been proposed (see Patent Document 3).

Japanese Patent Laid-Open No. 4-133792 JP 2010-234762 A JP 2010-89516 A

  However, in Patent Document 1, which is an improvement measure for a thermal transfer recording medium, a cushioning property can be obtained when a layer selected from one or more of a dye layer and an intermediate layer contains bubbles, but on the other hand, from a thermal head or the like. Therefore, there is a problem in that the heat transfer is hindered and a sufficient print density cannot be obtained.

  Further, in Patent Documents 2 and 3 that are measures for improving the thermal transfer image receiving sheet, since hollow particles and porous inorganic particles are used, these tend to cause unevenness on the surface of the receiving layer of the thermal transfer image receiving sheet. Still, there are problems of missing images and unevenness.

  SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a thermal transfer recording medium that can prevent image omission and unevenness during thermal transfer even in a receiving layer lacking in surface smoothness.

  The present inventors have found that the above problem can be achieved by changing the particle size of the particles added to the thermal transfer layer and the film thickness of the thermal transfer layer depending on the length of the concave portion on the surface of the receptor layer in the width direction. The invention has been completed.

  The invention according to claim 1 of the present invention is a thermal transfer recording medium for forming an image through heat on a thermal transfer member having at least one linear cross-sectional concave shape having a width L, and comprising at least a dye, It has a thermal transfer layer composed of a binder resin and particles, and the ratio [L / r] of the average particle diameter r of the particles to the length L of the width is 0.5 to 1.5. Is a thermal transfer recording medium. That is, the ratio between the average particle diameter r of the particles and the length L of the width is also applied to a thermal transfer member having at least one linear cross-sectional concave shape having a width L and inferior smoothness [ L / r] is maintained at 0.5 to 1.5, so that the particles contained in the thermal transfer layer can compensate the concave surface of the thermal transfer member, thereby forming an image free from image omission and density unevenness. it can.

  In the invention according to claim 2 of the present invention, the ratio [h / r] of the film thickness h of the thermal transfer layer and the average particle diameter r of the particles is 0.1 to 1.5. The thermal transfer recording medium according to claim 1. That is, when the ratio [h / r] of the film thickness h of the thermal transfer layer to the average particle diameter r of the particles is 0.1 to 1.5, the smoothness of the concave shape of the linear cross section is inferior. Also for the heat-transferred body, the particles do not fall off from the heat-transfer layer, and the concave surface of the heat-transferred body having poor smoothness can be compensated for and a good image can be formed.

  According to the present invention, it is possible to provide a thermal transfer recording medium capable of forming an image without image omission or unevenness during thermal transfer even with a thermal transfer body with poor smoothness.

It is a cross-sectional schematic diagram of one embodiment of the thermal transfer member of the present invention. It is a cross-sectional schematic diagram of one Embodiment of the thermal transfer layer of this invention. It is an expansion plane schematic diagram of one embodiment of the receiving layer surface of the present invention.

  Hereinafter, the present invention will be described in more detail with reference to the drawings. FIG. 1 is a cross-sectional view of the thermal transfer member 1. The thermal transfer body 1 includes a support 2 for the thermal transfer body and a receiving layer 3. The support 2 can be the same as the support 5 for a thermal transfer recording medium described later, and a substrate having mechanical strength, flexibility, heat resistance and the like is preferable. Specific examples include polyesters such as polyethylene terephthalate and polyethylene naphthalate, plastic films such as polyethylene, polyvinyl chloride, polycarbonate, polyester, polysulfane, polyimide, polyvinyl alcohol, aromatic polyamide, and aramid film, fine paper, and coats. Examples thereof include paper base materials such as paper and synthetic paper. Although there is no limitation in particular in the thickness of the said support body 2, Generally 25-250 micrometers, Furthermore, 75-200 micrometers is preferable.

  Further, as the receiving layer 3, when a sublimation dye is used for the thermal transfer layer, for example, butyral resin having a dyeing property, polyethylene, polyurethane, polypropylene, polyvinyl chloride, polybutadiene, polyvinyl acetate, vinyl chloride-acetic acid Thermoplastic resins such as vinyl copolymers, vinyl chloride / acrylic compound copolymers, ethylene-vinyl acetate copolymers, polyamides, polyesters, polycaprolactones, polyvinyl acetals, epoxies, ketones, or modified resins and blends thereof. And these cross-linked products. These may be used alone or in combination of two or more. If the film thickness of the receiving layer 3 is too thin, the reflection density of the image is lowered and it becomes difficult to form a sufficient image. On the other hand, if the thickness is too large, image quality such as color bleeding is deteriorated. Therefore, it is generally 1 to 30 μm, preferably 3 to 10 μm.

  The receiving layer 3 preferably contains various release agents for the purpose of preventing thermal fusion with the thermal transfer recording material during image formation. As such a release agent, a known release agent can be appropriately selected and used. For example, various oils such as silicone-based, fluorine-based, and phosphate-based oils, surfactants, various particles such as metal oxide, silica, and wax can be used, and among these, silicone oil is preferably used. Moreover, although the addition amount changes with structural conditions of a receiving layer, generally it is preferable to mix | blend by 1 to 30 weight%.

  A heat insulating layer may be provided between the receiving layer 3 and the support 2 for the thermal transfer member in order to prevent heat from being diffused from a thermal head or the like and efficiently transfer the dye from the thermal transfer layer to the receiving layer. good.

  The heat insulation layer preferably contains hollow particles. As the material for forming the walls of the hollow particles, conventionally known materials can be used, and examples thereof include acrylonitrile, vinylidene chloride, and a polymer of styrene acrylate. The hollow particles preferably have a particle size of 0.1 to 10.0 μm, and more preferably 0.5 to 5.0 μm. When the particle diameter of the hollow particles is smaller than 0.1 μm, the porosity becomes small, so that a sufficient heat insulating effect cannot be obtained. On the other hand, if it is larger than 10.0 μm, the hollow particles are liable to be crushed during production, and a sufficient heat insulating effect cannot be obtained.

  In the case of the above-described thermal transfer body 1, when hollow particles are used for the underlying heat insulating layer, the receiving layer is also affected by the unevenness, and thus the unevenness is formed on the surface of the receiving layer. Further, when the receiving layer is prepared from an emulsion, irregularities may be formed on the surface due to the influence of drying or the like. Various particles added to the receiving layer to prevent heat fusion also cause irregularities on the surface of the receiving layer. The thermal transfer body of the present invention can be applied to the above-described thermal transfer body having concave and convex portions on the receiving layer surface.

  FIG. 2 is a schematic cross-sectional view of the thermal transfer recording medium 4 of the present invention. The thermal transfer recording medium 4 of the present invention comprises a thermal transfer layer 6 comprising at least a dye, a binder resin and particles on one side of a support 5 for thermal transfer recording medium, and a binder resin on the other side of the support 5. It is comprised with the heat-resistant slipping layer 7 which becomes.

  The support 5 preferably has mechanical strength, flexibility, heat resistance, and the like. Specifically, polyethylene terephthalate, polyethylene naphthalate, polypropylene, cellophane, polycarbonate, polyvinyl chloride, polystyrene, polyimide, nylon, Plastic films such as polyvinylidene chloride, paper such as condenser paper and paraffin paper can be used. Polyethylene terephthalate is particularly preferable in terms of excellent smoothness, dimensional stability against heat, and handling properties during processing. Further, the thickness is preferably 2 to 25 μm, and more preferably 2 to 12 μm in consideration of cost.

  The thermal transfer layer 6 has a function of transferring the dye contained in the thermal transfer layer onto the thermal transfer body by heating from the heat-resistant slipping layer 7 side of the thermal transfer recording medium 4 with a thermal head. The thermal transfer layer of the present invention particularly refers to a sublimable thermal transfer layer.

  The thermal transfer layer 6 contains at least a sublimable dye, a binder resin, and particles. As the sublimable dye, conventionally known dyes can be used. Specifically, examples of yellow include Kayaset Yellow AG, Kayaset Yellow TDN, PYT52, Plast Yellow 8040, Holon Brilliant Yellow S6GLPI, and the like. Examples of magenta include Kaya Set Red B, Kaya Set Red 130, Sele Red 7B, Macrolex Red Violet R, C.I. I. Disperse thread 60 and the like can be mentioned. Examples of cyan include Kayaset Blue 714, Ceres Blue GN, MS Blue 50, TSD-44, C.I. I. Solvent Blue 63, C.I. I. Solvent blue 36 etc. are mentioned, However, It is not limited to these.

  As a binder resin used for the thermal transfer layer 6 in combination with a sublimation dye, conventionally known binder resins can be used. Polyvinyl acetal resin, polyvinyl butyral resin, polyester resin, phenoxy resin, styrene-acrylonitrile copolymer resin, ethyl cellulose, hydroxy Although resin excellent in heat resistance, dye transferability, etc., such as ethyl cellulose and polycarbonate, can be used, polyvinyl acetal resin is preferable as a resin more excellent in heat resistance and dye transferability.

  The glass transition temperature of the binder resin used for the thermal transfer layer 6 in combination with the sublimation dye is preferably 50 ° C. or higher. When the glass transition temperature is 50 ° C. or lower, the thermal transfer layer 6 is fused to the thermal transfer body during thermal transfer. This is not preferable because it tends to be easy to perform and a problem occurs in the storage stability of the thermal transfer recording medium. Furthermore, the ratio of the sublimable dye and binder resin contained in the thermal transfer layer 6 is preferably 100: 50 to 100: 300.

  The thermal transfer layer 6 may contain a crosslinking agent. As a crosslinking agent used for the thermal transfer layer 6 in combination with a sublimable dye and a binder resin, conventionally known crosslinking agents can be used. By containing a cross-linking agent, heat resistance is improved and deformation of the thermal transfer recording medium can be prevented. Examples of the crosslinking agent having more excellent heat resistance include polyisocyanates, which are used in combination with acrylic, urethane, and polyester polyol resins, cellulose resins, and acetal resins.

  The thermal transfer layer 6 may contain a release agent. When a release agent is contained, the releasability due to the shape of the surface of the thermal transfer layer is further improved. For example, various oils such as silicones, fluorines, and phosphates, surfactants, various fillers such as metal oxides and silicas, and the like can be used. Among these, it is preferable to use silicone oil.

  The film thickness of the thermal transfer layer 6 is 0.1 to 5.0 μm, preferably about 0.4 to 3.0 μm. If the thickness is less than 0.1 μm, sufficient color development sensitivity cannot be obtained, and if it exceeds 5.0 μm, the color development sensitivity is deteriorated.

The thermal transfer layer 6 described above contains at least particles 8. Examples of the particles include inorganic particles such as talc, clay, kaolin, magnesium oxide, magnesium hydroxide, and calcium carbonate, and organic particles such as polyethylene particles, polypropylene particles, polystyrene particles, and silicone particles.

  In the thermal transfer member having a concave shape on the surface of the receiving layer, the ratio [L / r] is 0.5 when the width of the recess on the surface of the receiving layer is L and the particle size of the particles 8 is r. By being in the range of -1.5, the particles 8 can fill the recesses on the surface of the receiving layer, and a uniform image can be obtained. That is, when the ratio is smaller than 0.5, the particle size of the particles is too small with respect to the width of the recess, so that the recess cannot be sufficiently filled and a uniform image cannot be obtained. On the other hand, when the ratio is larger than 1.5, the particle size of the particle is too large with respect to the width of the recess, so that the recess cannot be compensated for and a uniform image cannot be obtained. The concave shape of the linear cross section is not limited to the horizontal direction or the vertical direction of the thermal transfer member.

  Further, when the film thickness of the thermal transfer layer 6 is h, the ratio [h / r] to the particle size r is 0.1 to 1.5, so that the smoothness of the concave shape of the linear cross section is inferior. Also for the heat-transferred body, the particles do not fall off from the heat-transfer layer, and the concave surface of the heat-transferred body having poor smoothness can be compensated for and a good image can be formed. When the ratio is less than 0.1, particles often fall out of the thermal transfer layer, and a uniform image cannot be obtained. On the other hand, when the ratio is larger than 1.5, the particles are often buried in the thermal transfer layer, and a uniform image cannot be obtained.

  In order to improve the adhesion between the thermal transfer recording medium support 5 and the thermal transfer layer 6, an easy adhesion layer may be provided as an intermediate layer. In addition, a surfactant, an antiblocking agent, an antioxidant, an ultraviolet absorber, an antistatic agent, etc. may be added to the thermal transfer layer 6 as necessary, and a layer having these functions is laminated. May be.

  The heat resistant slipping layer 7 is provided on the opposite side of the support 5 to the thermal transfer layer 6 in order to prevent thermal contraction of the support 5 due to the heat of the thermal head and breakage of the support 5 due to friction with the thermal head. Is provided on the surface. Examples of the binder resin used for the heat resistant slipping layer 7 include acrylic resin, polyester resin, polyurethane resin, polyacetal resin, polyamide resin, and polyimide resin. For the purpose of improving the heat resistance, a crosslinking agent may be used in combination. Further, for the purpose of improving lubricity, a lubricant such as silicone oil may be used in combination, or the above-mentioned resin modified with silicone may be used.

  Moreover, in order to improve the adhesiveness between the said support body 5 and the heat resistant slipping layer 7, an easily bonding layer may be provided on the said support body 5, and a heat resistant slipping layer may be provided on it. On the contrary, when the heat resistant slipping layer is not provided, the heat resistance and the slipperiness may be improved by adjusting the surface roughness of the surface of the support 5 in contact with the thermal head by various methods.

  Various auxiliary agents such as wetting agents, dispersants, thickeners, antifoaming agents, colorants, antistatic agents, preservatives and the like used in general coated paper production are appropriately added to each coating layer. . Each coating layer is coated with a predetermined coating solution for each layer or two or more layers simultaneously by a known wet coating method such as bar coating, blade coating, air knife coating, gravure coating, roll coating, die coating, and drying. Can be obtained.

  Hereinafter, although an Example is described in detail, this invention is not limited to an Example.

<Example 1>
The ink composition for a heat-resistant slipping layer having the following composition was prepared, and the film thickness of the heat-resistant slipping layer after drying was 1 on one surface of a 4.5 μm-thick polyethylene terephthalate film as a support for a thermal transfer recording medium. Application and drying were carried out to a thickness of 0.0 μm. In the following, parts represent parts by weight. [Ink for heat-resistant slipping layer]
・ Acrylic polyol resin 15 parts ・ 2-6, Tolylene diisocyanate 5 parts ・ Amino-modified silicone oil 1 part ・ Methyl ethyl ketone 40 parts ・ Toluene 40 parts

Next, an ink for a thermal transfer layer having the following composition is prepared, and applied to the other surface of the substrate so that the thickness of the dried thermal transfer layer is 1.0 μm and dried, and then the thermal transfer recording medium of the present invention. Got.
[Ink for thermal transfer layer]
・ C. I. Solvent Blue 63 2.5 parts C.I. I. Solvent Blue 36 2.5 parts, polyvinyl acetal resin 5 parts, silicone filler (average particle size: 1.0 μm) 1 part, methyl ethyl ketone 60 parts, toluene 30 parts

Next, art paper having a thickness of 180 g / m 2 was used as a support for the thermal transfer member, and a receiving layer ink having the following composition was applied to one side of the paper so that the film thickness after drying was 4 μm and dried (100 And a thermal transfer member having an image receiving layer was obtained. When the obtained receiving layer surface was confirmed with an optical microscope, a linear concave shape was formed on the receiving layer surface, and the width of the concave portion was 1.0 μm.
(Receptive layer ink)
・ 97 parts urethane resin ・ 1 part associative urethane thickener ・ 2 parts sulfonic acid surfactant ・ 200 parts water

<Example 2>
In the thermal transfer layer ink composition, a thermal transfer recording medium was obtained in the same manner as in Example 1 except that the average particle size of the silicone filler was 2.0 μm and the thickness of the dried thermal transfer layer was 0.2 μm. It was.

<Example 3>
A thermal transfer recording medium was obtained in the same manner as in Example 1 except that the average particle size of the silicone filler in the thermal transfer layer ink composition was 0.7 μm.

<Example 4>
In the thermal transfer layer ink composition, a thermal transfer recording medium was obtained in the same manner as in Example 1 except that the average particle size of the silicone filler was 1.4 μm and the thickness of the dried thermal transfer layer was 0.2 μm. It was. In addition, a thermal transfer member was obtained in the same manner as in Example 1 except that the receiving layer ink was applied and then dried at 95 ° C., and the width of the recess was adjusted to 2.0 μm.

<Example 5>
In the thermal transfer layer ink composition, a thermal transfer recording medium was obtained in the same manner as in Example 1 except that the average particle size of the silicone filler was 2.0 μm and the thickness of the dried thermal transfer layer was 3.0 μm. It was.

<Example 6>
A thermal transfer recording medium was obtained in the same manner as in Example 1 except that the thickness of the thermal transfer layer after drying of the ink composition for the thermal transfer layer was 2.0 μm.

<Example 7>
The receiving layer ink was applied onto the base material sheet and dried at 95 ° C. to adjust the width of the recesses to 2.0 μm. Further, in the thermal transfer layer ink composition, the thermal transfer recording medium was prepared in the same manner as in Example 1 except that the average particle size of the silicone filler was 2.0 μm and the thickness of the dried thermal transfer layer was 0.1 μm. Obtained.

<Comparative Example 1>
A thermal transfer recording medium was obtained in the same manner as in Example 1 except that the thickness of the thermal transfer layer after drying of the ink composition for the thermal transfer layer was 2.0 μm. In addition, a thermal transfer member was obtained in the same manner as in Example 1 except that the receiving layer ink was applied and then dried at 95 ° C., and the width of the recess was adjusted to 2.0 μm.

<Comparative example 2>
After applying the ink for the receiving layer, drying was carried out at 95 ° C., and a thermal transfer medium and a thermal transfer recording medium were obtained in the same manner as in Example 1 except that the width of the recess was adjusted to 2.0 μm.

<Comparative Example 3>
In the thermal transfer layer ink composition, a thermal transfer recording medium was obtained in the same manner as in Example 1 except that the average particle size of the silicone filler was 2.0 μm and the thickness of the dried thermal transfer layer was 0.1 μm. It was. In addition, a thermal transfer member was obtained in the same manner as in Example 1 except that after applying the ink for the receiving layer, drying was performed at 90 ° C. and the width of the recess was adjusted to 4.0 μm.

<Comparative example 4>
In the thermal transfer layer ink composition, a thermal transfer recording medium was obtained in the same manner as in Example 1 except that the average particle size of the silicone filler was 2.0 μm and the thickness of the dried thermal transfer layer was 4.0 μm. It was. In addition, a thermal transfer member was obtained in the same manner as in Example 1 except that the receiving layer ink was applied and dried at 105 ° C. to adjust the width of the recess to 0.5 μm.

<Comparative Example 5>
In the thermal transfer layer ink composition, a thermal transfer recording medium was obtained in the same manner as in Example 1 except that the average particle size of the silicone filler was 2.0 μm and the thickness of the dried thermal transfer layer was 2.0 μm. It was. In addition, a thermal transfer member was obtained in the same manner as in Example 1 except that the receiving layer ink was applied and dried at 105 ° C. to adjust the width of the recess to 0.5 μm.

<Comparative Example 6>
In the thermal transfer layer ink composition, a thermal transfer recording medium was obtained in the same manner as in Example 1 except that the average particle size of the silicone filler was 2.0 μm and the thickness of the dried thermal transfer layer was 0.1 μm. It was. In addition, a thermal transfer member was obtained in the same manner as in Example 1 except that the receiving layer ink was applied and dried at 105 ° C. to adjust the width of the recess to 0.5 μm.

<Evaluation items and evaluation methods>
The thermal transfer layer surface of each thermal transfer recording medium obtained in Examples 1 to 7 and Comparative Examples 1 to 6 and the receiving layer surface of the transfer target are overlapped, and the thermal transfer recording medium side of the thermal transfer recording medium is passed through a thermal head. Heating and pressurization were performed to perform printing (image formation). The following image uniformity was evaluated for each obtained image. The results are shown in Table 1.
-Image uniformity The image uniformity of the obtained image was visually evaluated. ◎ if the image is uniform, there are some omissions or unevenness in the image, ○ if there are no omissions or unevenness in practical use, ○ if there are a lot of omissions or unevenness in the image, a level that is problematic in practice It evaluated by x.

<Comparison result>
The thermal transfer recording media according to the products of the present invention obtained in Examples 1 to 5 were able to obtain good image quality free from image omission and density unevenness even on a thermal transfer medium lacking in smoothness of the receiving layer. Further, from Example 6, when [h / r] is larger than 1.5, particles that are buried in the dye layer have come out. It was confirmed that unevenness occurred. Also, from Example 7, when [h / r] is smaller than 0.1, particles in the dye layer may fall off from the dye layer, and there is a practical problem in the image. None, but missing or unevenness was confirmed.

  On the other hand, all of the comparative example products obtained in Comparative Examples 1 to 6 were defective in quality and could not obtain a practical image quality. Specifically, from Comparative Examples 1 to 3, since the [L / r] is larger than 1.5, the average particle diameter r is too small with respect to the width L of the concave portion. As a result, it was confirmed that a large number of omissions and unevenness which are practically problematic occurred. Further, from Comparative Examples 4 to 6, since the [L / r] is smaller than 0.5, the average particle diameter r is too large with respect to the width L of the concave portion. It was confirmed that a number of problem level omissions and unevenness occurred.

  The thermal transfer recording medium of the present invention is widely used for monochrome printing such as characters and diagrams, and color printing such as digital camera images or computer graphics images.

DESCRIPTION OF SYMBOLS 1 ... The thermal transfer body 2 ... The support body 3 for a thermal transfer body ... Receptive layer 4 ... The thermal transfer recording medium 5 ... The support body 6 for a thermal transfer recording medium ... The thermal transfer layer 7 ... The heat resistant slipping layers 8a-8f ... Particles

Claims (2)

  A thermal transfer recording medium for forming an image through heat on a thermal transfer member having at least one linear cross-sectional concave shape having a width L, and having a thermal transfer layer comprising at least a dye, a binder resin and particles The thermal transfer recording medium is characterized in that the ratio [L / r] of the average particle diameter r of the particles to the length L of the width is 0.5 to 1.5.   2. The thermal transfer recording medium according to claim 1, wherein a ratio [h / r] of a film thickness h of the thermal transfer layer and an average particle diameter r of the particles is 0.1 to 1.5.

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