JP2014198467A - Thermosensitive transfer recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal transfer recording medium capable of inhibiting migrations of dyes, additives, etc. included within a thermal transfer layer to the surface of the thermal transfer layer during a long-term storage and of forming a homogeneous image unaccompanied by image deletion due to the dropout of particles.SOLUTION: The provided thermosensitive transfer recording medium 1 is a thermosensitive transfer recording medium 1 obtained by configuring, on one surface of a substrate 2, a thermal transfer layer 3 including a dye, a binder resin, and particles and, on the other surface of the same, a heat-resistant lubricant layer 4 where the binder resin consists of a polyvinyl acetal resin having a glass transition point of 100°C or above and a polyvinyl butyral resin having a glass transition point of 75°C or below in a state where the former-to-latter mixing ratio of both is being confined to a range of 97/3-50/50.

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 method, a thermal transfer layer surface of a thermal transfer recording medium provided with a thermal transfer layer containing a dye or a binder on a support and a receiving layer for receiving the dye on another support are provided. The dye in the thermal transfer layer is heated by a thermal head whose temperature is controlled by text or image information from the surface of the thermal transfer recording medium that is not provided with the thermal transfer layer. By sublimating and transferring to the receiving layer, a desired character or image is formed.

  On the other hand, in the case of the melt-type thermal transfer method, the surface of the thermal transfer recording medium provided with a heat-fusible thermal transfer layer containing a pigment, wax or the like on the support, and the coating provided with a receiving layer on the other support. By superimposing the receiving layer surface of the thermal transfer body on each other and heating with a thermal head or the like, 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.

  Currently, among the thermal transfer systems, the sublimation transfer system can easily form full-color images with various functions of the printer, so digital camera self-prints, cards such as identification cards, amusement output, etc. Widely used. Along with the diversification of such applications, there is a growing demand for smaller size, higher speed, lower cost, and durability for the printed material obtained. In recent years, durability has been given to the printed material on the same side of the base sheet. 2. Description of the Related Art Thermal transfer recording media having a plurality of thermal transfer layers provided so as not to overlap protective layers and the like that have been widely used have become quite popular.

  In the case of the sublimation type thermal transfer method, when the surface of the thermal transfer layer faces the surface of the thermal transfer body during printing, the releasability due to fusion to the surface of the thermal transfer body due to heat, and the accompanying disturbance of the image, etc. becomes a problem. There are many cases. Further, the thermal transfer member is installed in the printer in the form of a roll wound around a winding shaft, and is held in a state where the surface of the thermal transfer layer and the back surface of the support (generally provided with a heat-resistant slip layer) are in contact. When the retained time is long or the winding pressure is large, the dye or additive contained in the thermal transfer layer migrates to the heat-resistant slipping layer on the back (setback), and the migrated dye In addition, there is a problem that the additive stains the thermal head during thermal transfer.

  Many methods have been proposed to solve the above problems. For example, in Patent Document 1, a method for preventing fusion of a thermal transfer layer to a receiving layer by containing fine particles having a particle size of 1.0 μm or less and heat-meltable fine particles having a particle size of 5 μm or more in the thermal transfer layer. Has proposed. Patent Document 2 proposes a method of preventing set-off by forming an uneven shape by particles.

  However, in patent document 1, since the particle | grains with a particle size of 5 micrometers or more are used, particle | grains fall out easily and wear of a thermal head is accelerated | stimulated by dropout. In Patent Document 2, although a certain effect is confirmed in the set-off, the amount of particles added is small and the effect is not sufficient.

JP 7-47774 A Japanese Patent Laid-Open No. 9-30133

  The present invention is a thermal transfer recording in which a dye or an additive contained in a thermal transfer layer suppresses migration to the surface of the thermal transfer layer during long-term storage, and can form a uniform image without image omission due to dropout of particles. The purpose is to provide a medium.

  The invention of claim 1 according to the present invention is a thermal transfer recording medium comprising a thermal transfer layer comprising a dye, a binder resin and particles on one side of a support and a heat-resistant slipping layer on the other side. The binder resin is composed of a polyvinyl acetal resin having a glass transition temperature of 100 ° C. or higher and a polyvinyl butyral resin having a glass transition temperature of 75 ° C. or lower, and the blending ratio is in the range of 97/3 to 50/50. The mass ratio m / M is 0.1 or more and 0.5 or less, the particle size of the particles is r, and the film thickness of the thermal transfer layer is h. In this case, the thermal transfer recording medium is characterized in that the ratio r / h is 1.0 to 2.5.

  The invention of claim 2 is the thermal transfer recording medium according to claim 1, wherein the thermal transfer layer has a surface roughness Ra of 0.25 to 0.45 μm.

  According to the first aspect of the present invention, the binder resin comprises a polyvinyl acetal resin having a glass transition temperature of 100 ° C. or higher and a polyvinyl butyral resin having a glass transition temperature of 75 ° C. or lower, and the blending ratio is 97/3. By being in the range of ˜50 / 50, migration of dye (migration to the support surface) can be suppressed during storage before use, and stable storability can be obtained. Also, during thermal transfer, the dye can be easily transferred from the thermal transfer layer, and a uniform image without omission can be obtained. That is, the effect of suppressing migration of dyes during storage can be obtained by the action of the polyvinyl acetal resin having a glass transition temperature of 100 ° C. or higher. In addition, due to the action of polyvinyl butyral resin having a glass transition temperature of 75 ° C. or less, the dye can be easily transferred from the thermal transfer layer during thermal transfer, and the effect of suppressing omission due to falling off can be obtained by gripping the particles strongly. A uniform transfer image without omission is obtained.

  Further, when the mass of the binder resin is M and the mass of the particles is m, by setting the mass ratio m / M to 0.1 or more, the content of the particles in the thermal transfer layer is increased, and the thermal transfer layer The surface shape can be roughened. As a result, the contact area with the heat-resistant slipping layer can be reduced during storage in the winding form, and the migration of the dye to the heat-resistant slipping layer can be suppressed. In this range, it is possible to prevent the particles from falling off the thermal transfer layer, and transfer without image omission is possible. On the other hand, when the mass ratio m / M is larger than 0.5, image omission and decrease in adhesion between the support and the thermal transfer layer occur. Therefore, m / M is preferably in the range of 0.1 to 0.5. .

  Further, when the particle diameter of the particles is r and the film thickness of the thermal transfer layer is h, the ratio r / h is set to 1.0 to 2.5 so that the particles can protrude from the surface of the thermal transfer layer. As a result, the contact area between the thermal transfer layer and the heat resistant slipping layer can be reduced, and the migration of the dye to the heat resistant slipping layer during storage can be suppressed.

  According to a second aspect of the present invention, the surface roughness Ra of the thermal transfer layer is set to 0.25 to 0.45 μm, so that the contact area with the heat-resistant slipping layer is reduced during storage in the winding form. And the migration of the dye to the heat-resistant slip layer can be suppressed. In addition, when the surface roughness is within this range, a good transfer image can be obtained without affecting the adhesion to the transfer medium during thermal transfer.

  As described above, by using the thermal transfer recording medium of the present invention, even if the thermal transfer body is held in a roll shape for a long time, the dye or additive contained in the thermal transfer layer is provided on the back surface of the support. Therefore, it is possible to form a uniform image without shifting to the heat-resistant slipping layer and without image omission due to dropout of particles.

It is a cross-sectional schematic diagram of one embodiment of the thermal transfer recording medium of the present invention.

  Hereinafter, the present invention will be described in more detail. FIG. 1 is a sectional view of a thermal transfer recording medium 1. As shown in FIG. 1, the thermal transfer recording medium 1 of the present invention comprises a support 2 having a thermal transfer layer 3 on one side and a heat-resistant slip layer 4 on the other side.

  The support 2 is not particularly limited as long as it has mechanical strength, flexibility, heat resistance, etc., which are generally used as a support for thermal transfer recording media. Specific examples include polyethylene terephthalate, polyethylene naphthalate, polypropylene, cellophane, polycarbonate, polyvinyl chloride, polystyrene, polyimide, nylon, polyvinylidene chloride and other plastic films, condenser paper, and paraffin paper. However, polyethylene terephthalate is particularly preferable. Moreover, the thickness of the support body 2 is 2-25 micrometers, More preferably, it is 2-12 micrometers.

  The support 2 may be provided with an easy-adhesion layer in order to improve the adhesion between the heat-resistant slip layer 4 or the thermal transfer layer 3. As the material used for the easy-adhesion layer, those having an affinity for both the support 2 and the heat-resistant slipping layer 4 or the thermal transfer layer 3 are suitable. Specifically, acrylic acid, methacrylic acid, maleic acid, etc. Unsaturated carboxylic acid resin, polyurethane resin, polyester resin and the like.

  The easy-adhesion layer has a thickness that does not hinder the transfer of heat from the thermal head to the thermal transfer layer, and is 0.01 to 1 μm, more preferably 0.05 to 0.5 μm. The easy-adhesion layer can be formed by applying a coating solution on a support by a known coating method. Moreover, in the case of a plastic film, you may form simultaneously in the process of forming a plastic film. Moreover, you may improve adhesiveness by adjusting the surface roughness of the one or both surfaces of the support body 2 without providing an easily bonding layer.

  The thermal transfer layer 3 contains at least a dye, a binder resin, and particles, and the dye is particularly preferably a sublimable dye.

  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.

  Here, the blending ratio (solid content ratio) of the dye and the binder resin in the thermal transfer layer (30) is preferably dye / resin = 10/100 to 300/100. This is because when the dye / resin ratio is less than 10/100, the amount of dye is too small and the color development sensitivity is insufficient and a good thermal transfer image cannot be obtained, and when this ratio exceeds 300/100, the resin This is because the solubility of the dye with respect to is extremely lowered, so that when the thermal transfer recording medium 1 is obtained, the storage stability is deteriorated and the dye is likely to be precipitated. The dye layer may contain known additives such as a dispersant, a viscosity modifier, and a stabilizer as long as the performance is not impaired.

  The binder resin according to the present invention is characterized by using a mixture of a polyvinyl acetal resin having a glass transition temperature of 100 ° C. or higher and a polyvinyl butyral resin having a glass transition temperature of 75 ° C. or lower. The polyvinyl acetal resin acts on the storage stability of the thermal transfer recording medium 1 and has an effect of suppressing migration (migration) of the dye contained in the thermal transfer layer 3 to the surface layer. Thereby, contamination by the dye of the heat-resistant slip layer 4 formed on the other surface of the support can be prevented. In addition, the polyvinyl butyral resin functions to facilitate the transfer of the dye during heat transfer (transfer to the transfer target) and the grip property of the particles due to the low glass transition temperature (suppresses dropping), A transfer image without image omission can be formed.

  Moreover, it is preferable that the compounding ratio is the range of 97 / 3-50 / 50. When the amount of the polyvinyl acetal resin is larger than this range, the migration of the dye during storage can be further suppressed, but the migration of the dye during transfer to the transferred material becomes worse. Further, when the polyvinyl butyral resin is less than this range, it is difficult to hold the particles in the thermal transfer layer and dropout occurs.

  As the particles contained in the thermal transfer layer 3, known particles can be used. In addition, an average particle diameter is the value measured by light intensity distribution, and can be measured with a well-known particle size measuring apparatus. For example, “RALD-7100” manufactured by Shimadzu Corporation may be used.

  Further, when the mass of the binder resin constituting the thermal transfer layer 3 is M and the mass of the particles is m, the mass ratio m / M is preferably 0.1 or more and 0.5 or less. When the mass ratio m / M is less than 0.1, the effect of roughening the surface of the thermal transfer layer 3 is insufficient, and when the thermal transfer layer 3 is stored in a wound shape (roll shape), the back surface of the support 2 The contact area with the heat resistant slipping layer 4 increases, and as a result, there arises a problem that the dye easily migrates. When the mass ratio m / M is larger than 0.5, the adhesiveness of the thermal transfer layer 3 is lowered, and there is a problem that abnormal transfer is likely to occur in a high temperature and high humidity environment. In addition, image omission occurs due to the large number of particles.

  Further, when the particle diameter of the particles is r and the film thickness of the thermal transfer layer is h, the ratio r / h is preferably 1.0 to 2.5. Within this range, there is a high possibility that particles protrude from the surface of the thermal transfer layer. As a result, the contact area between the thermal transfer layer and the heat-resistant slip layer can be reduced, and the heat-resistant slip of the dye during storage can be reduced. Transition to the sex layer can be suppressed. On the other hand, if r / h is less than 1.0, the contact area with the heat resistant slipping layer becomes too large, and it becomes difficult to suppress dye migration. On the other hand, if it exceeds 2.5, the contact area with the heat resistant slipping layer becomes too small to form a uniform image.

  Furthermore, the surface roughness Ra of the thermal transfer layer 3 is preferably 0.25 to 0.45 [μm]. When the surface roughness Ra is within this range, even if the surface roughness Ra is stored in a wound form, the transfer of the dye to the heat-resistant slip layer is suppressed, and a uniform image can be formed. On the other hand, when the surface roughness Ra is less than 0.25, the unevenness of the surface of the thermal transfer layer 3 is too small, the contact area between the thermal transfer layer and the heat-resistant slip layer is increased, and the back-off (dye transfer) is caused. It cannot be prevented sufficiently. On the other hand, when Ra exceeds 0.45, the contact area with the heat-resistant slipping layer becomes too small to form a uniform image. Furthermore, there is a problem that the dropped particles adhere to the heat resistant slipping layer and damage the thermal head.

  The film thickness of the thermal transfer layer 3 is 0.2 to 5.0 μm, preferably about 0.4 to 3.0 μm. If the thickness is less than 0.2 μm, sufficient color development sensitivity cannot be obtained, and if it exceeds 5.0 μm, the color development sensitivity is deteriorated.

  In the thermal transfer layer 3 according to the present invention, a crosslinking agent may be used in combination for the purpose of improving heat resistance. By containing a cross-linking agent, heat resistance is improved and deformation of the thermal transfer recording medium can be prevented. A conventionally well-known thing can be used as said crosslinking agent. 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 polyisocyanate preferably has a blending ratio of 0.05 to 0.20 with respect to the binder resin, and if it is less than 0.05, it lacks heat resistance. Occur. On the other hand, if it is larger than 0.20, there arises a problem that the print density is lowered.

  The thermal transfer layer 3 may contain a release agent. By including a release agent, sticking between the thermal transfer layer and the receiving layer during printing can be prevented. Examples of the release agent include various oils and surfactants such as silicone-based, fluorine-based and phosphate ester-based, and silicone-based or fluorine-based oils and surfactants are particularly preferable.

  Specifically, straight silicone oils such as dimethyl silicone and methylphenyl silicone, amino modification, epoxy modification, carbinol modification, mercapto modification, carboxyl modification, methacryl modification, polyether modification, phenol modification, one-end reaction as silicone series And non-reactive modified silicone oils such as polyether modified, aralkyl modified, fluoroalkyl modified, long chain alkyl modified, higher fatty acid ester modified, phenyl modified and the like. Examples of the fluorine-based agent include surfactants containing a fluoroalkyl group or a perfluoroalkyl group.

  The release agent is preferably in a weight ratio of 0.004 to 0.065 with respect to the dye layer. When the weight ratio is less than 0.004, sticking between the dye layer and the receiving layer during printing is likely to occur, and heat wrinkles become severe due to sticking, resulting in transfer unevenness. On the other hand, if it is larger than 0.065, the slipperiness with the receiving layer is improved, but the dye sublimation is inhibited, and transfer unevenness or a printed matter with a desired density cannot be obtained.

  Moreover, an antiblocking agent, an antioxidant, an ultraviolet absorber, an antistatic agent, etc. may be added to the thermal transfer layer 3 as necessary, and layers having these functions may be laminated. .

  The thermal transfer layer 3 is formed by applying a coating liquid for forming the thermal transfer layer on the support 2 by a wet coating method such as bar coating, blade coating, air knife coating, gravure coating, roll coating, and the like, followed by drying.

  The heat-resistant slip layer 4 according to the present invention is provided on the other surface of the support 2 (the surface opposite to the thermal transfer layer 3), and the thermal contraction of the support 2 due to the heat of the thermal head, Breakage of the support 2 due to friction is prevented. Examples of materials used for the heat resistant slipping layer 4 include cellulose resins, polyester resins, acrylic resins, vinyl resins, and polyurethane resins. 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.

  Further, the thermal transfer member according to the present invention comprises a support and a receiving layer. This support can be the same as that used as the support 2 of the thermal transfer recording medium 1 and preferably has mechanical strength, flexibility, heat resistance and the like. 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. The thickness of the support is not particularly limited, but is generally 25 to 250 μm, more preferably 75 to 200 μm.

  Further, as the receiving layer, 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-vinyl acetate. Uses thermoplastic resins such as copolymers, ethylene-vinyl acetate copolymers, polyamides, polyesters, polycaprolactones, polyvinyl acetals, epoxies, ketones, modified resins and blends thereof, and cross-linked products thereof. can do. These may be used alone or in combination of two or more.

  If the film thickness of the image receiving layer 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. In this case, the image receiving layer preferably contains various release agents for the purpose of preventing thermal fusion to the thermal transfer recording body 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, various particles such as surfactants, metal oxides, silica, and the like can be used. Among these, silicone oil is preferably used. The amount added varies depending on the constituent conditions of the image-receiving layer, but generally it is preferably 1 to 30% by weight.

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

<Example 1>
Using a polyethylene terephthalate film with a thickness of 4.5 μm as a support, applying and drying the thermal transfer layer forming ink composition having the following composition on one side so that the thickness of the thermal transfer layer after drying is 1.0 μm Then, a heat-resistant slip layer was formed on the other surface to obtain a thermal transfer recording medium. The ratio of the particle diameter r of the particles to the film thickness h of the thermal transfer layer was r / h = 2.0.

<Ink composition for forming a thermal transfer layer>
-Dye: C.I. I. Solvent Blue 63 (anthraquinone dye) 6.0 parts by mass / binder resin:
Polyvinyl acetal resin (Tg = 110 ° C.) 3.6 parts by mass Polyvinyl butyral resin (Tg = 68 ° C.) 0.4 parts by mass (Polyvinyl acetal resin / polyvinyl butyral resin = 90/10)
Particles: 0.6 parts by weight of silicone filler (manufactured by Shin-Etsu Silicone, KM-590, particle size r = 2.0 μm)
Solvent: 45.0 parts by mass of toluene 45.0 parts by mass of methyl ethyl ketone

Next, a laminate formed by sequentially laminating a foamed polypropylene film (thickness 50 μm), an adhesive resin layer, coated paper (coating amount: 108 g / m ² ), an adhesive resin layer, and a foamed polypropylene film (thickness 50 μm) is heat-transferred. The receiving layer forming ink having the following composition was applied to one surface of the substrate sheet, dried so that the film thickness after drying was 4 μm, and then aged at 45 ° C. for 1 week, and then the thermal transfer member Got.

<Ink composition for forming receiving layer>
-Vinyl chloride-vinyl acetate copolymer: 50.0 parts by mass (manufactured by Nissin Chemical Industry Co., Ltd., Solvein A)
-Silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., KF393): 2.0 parts by mass- Methyl ethyl ketone: 25.0 parts by mass- Toluene: 25.0 parts by mass

<Example 2>
A thermal transfer recording medium was obtained in the same manner as in Example 1 except that the thermal filler layer forming ink composition was changed to 0.4 parts by mass of the silicone filler.

<Example 3>
A thermal transfer recording medium was obtained in the same manner as in Example 1 except that the silicone filler was changed to 1.2 parts by mass among the thermal transfer layer forming ink composition.

<Example 4>
A thermal transfer recording medium was obtained in the same manner as in Example 2 except that the thickness of the thermal transfer layer was 0.8 μm and r / h was 2.5.

<Example 5>
A thermal transfer recording medium was obtained in the same manner as in Example 2 except that the thickness of the thermal transfer layer was 2.0 μm and r / h was 1.0.

<Example 6>
A thermal transfer recording medium was obtained in the same manner as in Example 5, except that the thermal filler layer forming ink composition was changed to 2.0 parts by mass of the silicone filler.

<Example 7>
Of the thermal transfer layer forming ink composition, except that the polyvinyl acetal resin (Tg = 110 ° C.) of the binder resin was 2.0 parts by mass and the polyvinyl butyral resin (Tg = 68 ° C.) was 2.0 parts by mass. A thermal transfer recording medium was obtained in the same manner as in Example 1.

<Example 8>
Of the thermal transfer layer forming ink composition, except that the binder resin polyvinyl acetal resin (Tg = 110 ° C.) was 3.88 parts by mass and the polyvinyl butyral resin (Tg = 68 ° C.) was 0.12 parts by mass. A thermal transfer recording medium was obtained in the same manner as in Example 1.

<Example 9>
Of the ink composition for the thermal transfer layer, the silicone filler (Momentive Performance Materials Japan GK, XC99-A8808, particle size 0.7 μm) is 2.0 parts, the film thickness is 0.7 μm, r A thermal transfer recording medium was obtained in the same manner as in Example 1 except that / h was set to 1.0.

<Comparative Example 1>
A thermal transfer recording medium was obtained in the same manner as in Example 1 except that 0.2 parts by mass of the silicone filler in the thermal transfer layer forming ink composition was used.

<Comparative example 2>
A thermal transfer recording medium was obtained in the same manner as in Example 1 except that the silicone filler was changed to 2.0 parts by mass in the thermal transfer layer forming ink composition.

<Comparative Example 3>
A thermal transfer recording medium was obtained in the same manner as in Example 4 except that 0.2 part by mass of the silicone filler in the thermal transfer layer forming ink composition was used.

<Comparative example 4>
A thermal transfer recording medium was obtained in the same manner as in Example 4 except that 1.2 parts by mass of the silicone filler in the thermal transfer layer forming ink composition was used.

<Comparative Example 5>
A thermal transfer recording medium was obtained in the same manner as in Example 5 except that 0.2 part by mass of the silicone filler in the thermal transfer layer forming ink composition was used.

<Comparative Example 6>
A thermal transfer recording medium was obtained in the same manner as in Example 5, except that the thermal transfer layer forming ink composition was changed to 2.8 parts by mass of the silicone filler.

<Comparative Example 7>
A thermal transfer recording medium was obtained in the same manner as in Example 2 except that the thickness of the thermal transfer layer was 4.0 μm and r / h was 0.5.

<Comparative Example 8>
A thermal transfer recording medium was obtained in the same manner as in Example 2 except that the film thickness of the thermal transfer layer was 0.5 μm and r / h was 4.0.

<Comparative Example 9>
A thermal transfer recording medium was obtained in the same manner as in Example 1 except that no silicone filler was added in the thermal transfer layer forming ink composition.
<Comparative Example 10>
Thermal transfer recording was carried out in the same manner as in Example 1 except that the polyvinyl acetal resin (Tg = 110 ° C.) as the binder resin was 4.0 parts by mass and the polyvinyl butyral resin was not used in the ink composition for forming the thermal transfer layer. A medium was obtained.

<Comparative Example 11>
Thermal transfer recording was conducted in the same manner as in Example 1 except that the binder resin polyvinyl butyral resin (Tg = 68 ° C.) was 4.0 parts by mass and the polyvinyl acetal resin was not used in the thermal transfer layer forming ink composition. A medium was obtained.

<Comparative Example 12>
A thermal transfer recording medium was obtained in the same manner as in Example 9 except that 2.8 parts of the silicone filler in the thermal transfer layer ink composition was used.

<Example 13>
A thermal transfer recording medium was obtained in the same manner as in Example 9 except that 4.0 parts of the silicone filler in the thermal transfer layer ink composition was used.

<Evaluation>
The thermal transfer recording media obtained in Examples 1 to 9 and Comparative Examples 1 to 13 are reversed, and the image quality, wrinkles, and dropout of particles when thermally transferred to the transfer medium described in Example 1 are used. The abnormal transfer was evaluated by the following method. The results are shown in Table 1 below.

-Set-back 100mm x 100mm cut out the thermal transfer recording medium surface of the thermal transfer recording medium facing the heat-resistant slipping layer on the back, and left for 100 hours in a 30% 50% environment while applying a load of 2kg, The presence or absence of setback of the dye to the heat-resistant slip layer was visually observed. The case where no set-off was confirmed was evaluated as ◯, the case where it was slightly confirmed was evaluated as Δ, and the case where it was clearly confirmed was evaluated as ×.

-Image quality It was visually confirmed whether defects such as omission occurred in the obtained image. The case where omission did not occur was evaluated as ◯, the case where it occurred was evaluated as x, and the case where it occurred slightly but there was no practical problem was evaluated as Δ.

-Print wrinkles It was visually confirmed whether or not print wrinkles occurred in the obtained image. A case where no print wrinkle was produced was evaluated as ◯, a case where a print wrinkle was produced was evaluated as x, and a case where print wrinkle was not generated but a deformation and elongation of the thermal transfer recording medium was large was evaluated as Δ.

-Dropping The obtained thermal transfer recording medium was observed with an optical microscope. The case where the filler did not fall off was evaluated as ◯, the case where the filler had dropped out was evaluated as ×, and the case where the filler was removed slightly was evaluated as Δ.

・ Abnormal transfer Printing was performed under the following conditions, and abnormal transfer was evaluated under a high temperature and high humidity environment.
Printing environment: 40 ° C / 60% RH
Applied voltage: 29V
Line cycle: 0.7msec
Print density: main scanning 300 dpi sub-scanning 300 dpi
As for abnormal transfer, ○ is indicated when abnormal transfer to the transfer object is not observed, Δ is indicated when abnormal transfer to the transfer object is very slight, and abnormal transfer to the transfer object is observed slightly. The case was evaluated as x, and the case where abnormal transfer to the transfer object was observed on the entire surface was evaluated as xx. Δ or more is a level where there is no practical problem.

<Comparison result>
As described above, from Examples 1 to 9, when the weight-based blending amount of the binder resin is M and the weight-based blending amount of the particles is m, the mass ratio m / M is 0.1 or more and 0. 0.5 or less, the ratio r / h of the particle diameter r of the particle to the film thickness h of the thermal transfer layer is 1 to 2.5, and the surface roughness Ra of the thermal transfer layer is 0.25 to 0.45 μm. Thus, it was confirmed that the set-off could be prevented and the omission of the image was prevented. In addition, it was confirmed that there are no problems in terms of particle dropout, wrinkles, and abnormal transfer.

  In Examples 3, 6, and 9, since the amount of particles added was large and the surface roughness was large, a slight drop occurred. In Examples 6 and 9, abnormal transfer occurred only slightly in a range where there was no practical problem under a high temperature and high humidity environment. In Example 5, when m / M = 0.1 and r / h = 1.0, the amount of particles was small, and the unevenness due to the particles was small. On the other hand, in Example 9, the compounding amount of the particles was sufficient, but since the particle size was small, the unevenness due to the particles became small, and slight settling occurred. From Example 7, since the ratio of the polyvinyl butyral resin was large, deformation and elongation of the thermal transfer recording medium occurred within a range that had no practical problem.

  In Comparative Examples 1, 3, and 5, the ratio r / h of the particle to the film thickness satisfies 1 to 2.5, but the mass ratio of the particles to the binder resin is less than 0.1, and the amount of particles added is small. For this reason, the contact area between the dye layer and the heat-resistant slipping layer is large, and the set-off cannot be sufficiently prevented.

On the other hand, in Comparative Examples 2, 4, and 6, since the surface roughness was larger than 0.45 μm and the surface irregularities were large, image omission occurred, and a slight drop of particles was confirmed. In Comparative Examples 2 and 4, the thermal transfer recording medium was greatly deformed and elongated.
In Comparative Examples 12 and 13, although the surface roughness satisfies 0.25 to 0.45 μm, image loss occurred because m / M was greater than 0.5. Furthermore, in Comparative Examples 6, 12, and 13, abnormal transfer slightly occurs in a high-temperature and high-humidity environment, which may cause a practical problem.

  In Comparative Example 7, r / h was 0.5, and there was no effect of reducing the contact area between the dye layer and the heat-resistant slip layer due to the particles, and set-off occurred. In Comparative Example 8, although r / h was 4.0, there were many dropouts of the particles, so that the effect of reducing the contact area between the dye layer and the heat-resistant slip layer due to the particles was small, and setback occurred. In addition, omission of images considered to be caused by particles also occurred. In Comparative Example 9, since no particles were present, the dye layer and the heat-resistant slipping layer were brought into close contact with each other and the set-off occurred. In Comparative Example 10, since a polyvinyl butyral resin having a temperature of 75 ° C. or lower was not added, it was difficult for the dye to migrate from the thermal transfer layer, and particles were lost. In Comparative Example 11, since only a polyvinyl butyral resin having a temperature of 75 ° C. or lower was used, heat resistance was insufficient and wrinkles were generated.

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

DESCRIPTION OF SYMBOLS 1 ... Thermal transfer recording medium 2 ... Support body 3 ... Thermal transfer layer 4 ... Heat-resistant slipping layer

Claims (2)

A thermal transfer recording medium comprising a dye, a binder resin and particles on one side of a support, and a heat-sensitive transfer recording medium provided with a heat-resistant slipping layer on the other side,
The binder resin consists of a polyvinyl acetal resin having a glass transition temperature of 100 ° C. or higher and a polyvinyl butyral resin having a glass transition temperature of 75 ° C. or lower, and the blending ratio is in the range of 97/3 to 50/50,
When the mass of the binder resin is M and the mass of the particles is m, the mass ratio m / M is 0.1 or more and 0.5 or less,
A thermal transfer recording medium, wherein the ratio r / h is 1.0 to 2.5, where r is the particle size of the particles and h is the film thickness of the thermal transfer layer.   2. The thermal transfer recording medium according to claim 1, wherein the arithmetic average roughness Ra of the surface of the thermal transfer layer is 0.25 to 0.45 [mu] m.