JP5568870B2 - Thermal transfer recording medium - Google Patents

Description

  In the present invention, a heat-sensitive transfer layer having at least a binder resin and a lubricant is laminated on one surface of a base film, and at least a heat-resistant slip layer having at least a binder resin and a lubricant is laminated on the other surface of the base film. The present invention relates to a thermal transfer recording medium.

  Conventionally, when performing thermal transfer recording by the thermal transfer method based on output information from computers, word processors, facsimiles, etc., a thermal transfer layer or thermal sublimation property made of heat-meltable ink on one side of the base film A thermal transfer recording medium in which a thermal transfer layer containing a dye and a heat-resistant slipping layer are provided on the other side is used.

  In thermal transfer recording using such a thermal transfer recording medium, the thermal transfer layer of the thermal transfer recording medium and the thermal transfer medium are stacked and heated from the heat-resistant slipping layer side of the base film of the thermal transfer recording medium by a thermal head. Is done by.

  In such thermal transfer recording, as the printing / image forming speed increases, the energy applied by the thermal head increases, resulting in the thermal transfer layer and the thermal transfer body being fused, or the thermal head and thermal transfer recording. The base film of the medium is fused, and if it is remarkable, the base film is broken to cause a problem that good image formation cannot be performed.

  In order to solve these problems, a thermal transfer recording medium (Patent Document 1) containing a polyvinyl butyral having a molecular weight of 60 to 200,000% or more in the thermal transfer layer, or a binder in the heat resistant slipping layer. A thermal transfer recording medium using a polyamide-imide resin as a resin (Patent Document 2) has been proposed.

Japanese Patent Laid-Open No. 60-101087 JP-A-7-179077

  However, in the former thermal transfer recording medium, since the thermal transfer layer contains polyvinyl butyral having poor fluidity at a ratio of 90% by weight or more, it is possible to form the thermal transfer layer with good coatability. This makes it difficult to form a thermal transfer recording medium having a uniform thickness, which makes it difficult to perform good thermal transfer recording. In the latter thermal transfer recording medium, the cost of the polyamideimide resin itself is high, and the production cost is high. Further, these thermal transfer recording media are expected to have the desired effect by specifying the component of only one binder resin in the thermal transfer layer or heat-resistant slipping layer. The point has not been fully resolved.

  The present invention has been made to solve the above-described problems, and can prevent fusion between the thermal transfer layer and the thermal transfer body during thermal transfer recording, and can reduce the so-called ribbon strength during thermal transfer recording. An object of the present invention is to provide a thermal transfer recording medium which is strengthened so that a good thermal transfer recording image without unevenness and streaks can be obtained.

In order to solve the above problems, the invention according to claim 1 is characterized in that a thermal transfer layer having at least a binder resin and a lubricant is provided on one side of the base film, and at least on the other side. In a heat-sensitive transfer recording medium comprising at least a heat-resistant slipping layer having a binder resin and a lubricant, the binder resin constituting the heat-sensitive transfer layer is polymerized with a polyvinyl acetal resin having a polymerization degree of 1100 or more and a glass transition temperature of 100 ° C. or more. It consists of a mixture of a polyvinyl acetal resin having a temperature of less than 1100 and a glass transition temperature of less than 100 ° C., and the binder resin constituting the heat resistant slipping layer is a reaction product of a thermoplastic resin having a glass transition temperature of 70 ° C. or more and a polyvalent isocyanate. the lubricant for thermal transfer layer contains 0.003 to 0.05 by weight, the heat-resistant lubricating To a thermal transfer recording medium characterized by containing a specific gravity 3.0 × ^{10 3} kg / ^m 3 or more inorganic particles.

  The invention according to claim 2 is the heat-sensitive transfer recording medium according to claim 1, wherein the heat-sensitive transfer layer contains 60% by weight or more of a polyvinyl acetal resin having a degree of polymerization of 1100 or more and a glass transition temperature of 100 ° C. or more. A polyvinyl acetal resin having a degree of polymerization of 90% by weight or less, a degree of polymerization of less than 1100, and a glass transition temperature of less than 100 ° C. is respectively contained in a proportion of 10% by weight to 40% by weight.

  Furthermore, the invention described in claim 3 is the thermal transfer recording medium described in claim 1 or 2, wherein the lubricant in the thermal transfer layer is a silicone-based lubricant.

  Furthermore, the invention according to claim 4 is the thermal transfer recording medium according to claim 1, characterized in that the thermoplastic resin in the heat-resistant slipping layer has a reactive polyol group. To do.

  Furthermore, the invention according to claim 5 is the thermal transfer recording medium according to claim 1 or 4, wherein the lubricant in the heat resistant slipping layer contains a phosphate ester surfactant and a stearate. It is characterized by.

  The heat-sensitive transfer recording medium according to the present invention has a heat-sensitive transfer layer having at least a binder resin and a lubricant on one surface of a base film, and a heat-resistant slip layer having at least a binder resin and a lubricant on the other surface. Is a heat-sensitive transfer recording medium in which at least a binder resin constituting the heat-sensitive transfer layer is a polyvinyl acetal resin having a polymerization degree of 1100 or more and a glass transition temperature of 100 ° C. or more, a polymerization degree of less than 1100 and a glass transition temperature of 100. Since the binder resin constituting the heat resistant slipping layer is made of a reaction product of a thermoplastic resin having a glass transition temperature of 70 ° C. or more and a polyvalent isocyanate, the heat-sensitive transfer layer and the thermal transfer layer Prevents the body from fusing, and the so-called ribbon strength during thermal transfer recording is strong, so recording irregularities and streaks No good thermal transfer recording can be performed.

It is explanatory drawing which shows schematic cross-sectional structure of the thermal transfer recording medium based on this invention.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to FIG.

  FIG. 1 is an explanatory view showing a schematic cross-sectional structure of a thermal transfer recording medium according to the present invention.

  As shown in FIG. 1, the thermal transfer recording medium (1) has a thermal transfer layer (3) having at least a binder resin and a lubricant on one surface of the base film (2). ) Is laminated with a heat resistant slipping layer (4) having at least a binder resin and a lubricant.

  The binder resin constituting the thermal transfer layer (3) is a mixture of a polyvinyl acetal resin having a polymerization degree of 1100 or more and a glass transition temperature of 100 ° C. or more and a polyvinyl acetal resin having a polymerization degree of less than 1100 and a glass transition temperature of less than 100 ° C. At the same time, the binder resin constituting the heat resistant slipping layer (4) consists of a reaction product of a thermoplastic resin having a glass transition temperature of 70 ° C. or higher and a polyvalent isocyanate.

  The base film (2) may be any film as long as it has conventionally known heat resistance and strength. For example, polyethylene terephthalate film, polyethylene naphthalate film, polypropylene film, polysulfone film, polyimide film, polyvinyl alcohol A film, a polycarbonate film, a polystyrene film, etc. are mentioned. The thickness of the base film (2) may be about 2.0 to 50 μm, but considering the transfer suitability and the like, about 2.0 to 9.0 μm is preferable.

  When a thermal transfer layer is to be provided on such a base film (2), as a binder resin constituting the thermal transfer layer, for example, when a polyvinyl acetal resin having a polymerization degree of 1100 or more is used alone, Since the entanglement between the molecules of the polyvinyl acetal is weakened and the retention of the dye is weakened, the dye contained in the thermal transfer layer is likely to sublime, and the transfer density of the transferred image recorded on the heat-transferred material is increased. is there. Also, during thermal transfer recording, the thermal transfer recording medium is heated to 200 ° C. or higher by a thermal head for a short time. Therefore, if the glass transition temperature of the binder resin is low, the thermal transfer layer containing it is fused to the thermal transfer medium. Although there is a risk of wearing, using a binder resin having a glass transition temperature of 100 ° C. or higher can reduce the risk.

  On the other hand, if the degree of polymerization of the binder resin is too high, the fluidity is lowered, and the coating property of the coating liquid for forming a thermal transfer recording layer containing such a binder resin is lowered. It is difficult to obtain a heat-sensitive recording layer.

On the other hand, in the thermal transfer recording medium of the present invention, as described above, the binder resin constituting the thermal transfer layer has a polymerization degree of 1100 or more and a glass transition temperature of 100 ° C. as the binder resin constituting the thermal transfer layer. A mixture of the above polyvinyl acetal resin and a polyvinyl acetal resin having a degree of polymerization of less than 1100 and a glass transition temperature of less than 100 ° C. is used.
As a result, the thermal transfer layer does not fuse to the thermal transfer body, and the coating liquid for forming the thermal transfer recording layer containing this binder resin has good coatability, so a uniform coating film can be obtained. A heat-sensitive transfer layer having a uniform thickness can be obtained, and thus good heat-sensitive transfer recording can be performed.

  The mixing ratio of the two binder resins described above is such that the polyvinyl acetal resin having a polymerization degree of 1100 or more and a glass transition temperature of 100 ° C. or more is 60% by weight or more and 90% by weight or less, the polymerization degree is less than 1100, and the glass transition temperature is 100 ° C. It is preferable that less than polyvinyl acetal resin is 10 to 40 weight%.

  On the other hand, a lubricant is contained in the thermal transfer layer (3). However, the inclusion of the lubricant can more reliably prevent sticking between the thermal transfer layer and the thermal transfer body during thermal transfer recording. Examples of the lubricant include various oils and surfactants such as silicone-based, fluorine-based, and phosphate ester-based, and silicone-based oils and surfactants are particularly preferable.

  More specifically, as a silicone type, straight silicone oil 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 Reactive modified silicone oils such as reactive and heterogeneous functional group modifications, as well as non-reactive modified silicone oils such as polyether modified, aralkyl modified, fluoroalkyl modified, long chain alkyl modified, higher fatty acid ester modified, phenyl modified, etc. Is mentioned.

  Such a lubricant is preferably contained in a weight ratio of about 0.1 or less with respect to the heat-sensitive transfer layer (3). It is more preferable to make it contain in the range of about 0.003 to 0.05. When the weight ratio is smaller than 0.003, the thermal transfer layer and the thermal transfer material are easily adhered during thermal transfer recording, and when they are adhered, thermal wrinkles are generated more. Will occur. On the other hand, when the weight ratio is larger than 0.05, the slipping property with respect to the thermal transfer medium is improved, but the dye sublimation is hindered and transfer unevenness or thermal transfer recording with a desired density may not be performed.

  In the thermal transfer layer (3) having the binder resin and the lubricant, the components contained therein are transferred onto the thermal transfer member by heating with a thermal head from the opposite side of the thermal transfer layer of the thermal transfer recording medium, It contains colorants such as heat sublimation dyes for forming letters and images.

  The heat-sensitive transfer layer containing a heat-sublimable dye as a colorant is prepared by, for example, forming a thin film of a coating solution for forming a heat-sensitive transfer layer prepared by blending a heat-sublimable dye, a binder resin, a solvent, etc. on a base film. It can be obtained by applying and then drying. The coating amount of the heat-sensitive transfer layer forming coating solution is preferably adjusted so that the dry film thickness is about 1.0 μm.

  As the sublimable dye, a sublimable disperse dye is preferably used mainly. For example, diarylmethane, triarylmethane, thiazole, methine, azomethane, xanthene, axazine, thiazine, azine, acridine, azo, spirodipyran, isorinospiropyran, fluorane, rhodamine Examples include sublimable dyes such as ductams and anthraquinones.

  More specifically, examples of yellow components include C.I. I. Solvent Yellow 14, 16, 29, 30, 33, 56, 93 etc., C.I. I. Disperse Yellow 7, 33, 60, 141, 201, 231 and the like include magenta components such as C.I. I. Solvent Red 18, 19, 27, 143, 182, C.I. I. Disperse thread 60, 73, 135, 167, C.I. I. Disperse violet 13, 26, 31, 56, etc., and cyan components include C.I. I. Solvent Blue 11, 36, 63, 105, C.I. I. Disperse blue 24, 72, 154, 354, etc. are mentioned, respectively, but it is not necessarily limited to these. These dyes may be used alone or in combination.

  Moreover, about 0.1-3.0 are preferable and the weight ratio (dye / binder resin) of an above-described dye and binder resin is more preferable if it is about 0.5-1.5. If it is less than 0.1, the dye concentration becomes low, so that the color development sensitivity becomes insufficient and it becomes difficult to obtain a good thermal transfer image. On the other hand, when the concentration of the dye is higher than 3.0, the solubility of the dye in the binder resin is extremely lowered, which is not preferable because the storage stability of the thermal transfer layer is lowered and the dye is likely to precipitate.

  Further, the thermal transfer layer (3) may contain a crosslinking agent for the purpose of improving heat resistance. By containing a crosslinking agent, heat resistance is improved, and deformation of the thermal transfer recording medium can be prevented during thermal recording. An example of the crosslinking agent is polyisocyanate, which can be used in combination with acrylic, urethane, or polyester polyol resins, cellulose resins, acetal resins, and the like.

On the other hand, as a reaction product of a thermoplastic resin having a glass transition temperature of 70 ° C. or higher and a polyvalent isocyanate constituting the heat-resistant slip layer (4), for example, a reaction product of a polyvinyl butyral resin and a diisocyanate, a polyester resin and a polyisocyanate Reaction product of cellulose acetate and polyisocyanate, reaction product of acrylic polyol and polyisocyanate, reaction product of polyester polyol and polyisocyanate, reaction product of urethane polyol and polyisocyanate, and the like.
In addition, examples of the thermoplastic resin include a resin having a reactive polyol group, particularly from the viewpoint of reactivity and compatibility with the polyvalent isocyanate.

The lubricant contained in the heat resistant slipping layer (4) has a function of imparting slipperiness to the heat resistant slipping layer (4) when heated from the thermal head, and is dissolved in a molecular form in the binder resin. Existing. Therefore, compared to the case where a solid lubricant is added, a rough feeling in the thermal transfer recording portion is less likely to occur.
As such a lubricant, stearates and phosphate ester surfactants are preferably used. Due to the presence of stearates and phosphate ester surfactants, the reactivity of thermoplastic resins with reactive polyol groups and polyisocyanates increases, resulting in the transfer of the thermal transfer layer to the heat-resistant slipping layer. It becomes difficult to happen.

  Examples of the stearate include sodium stearate, zinc stearate, calcium stearate, potassium stearate, magnesium stearate and the like. Of these, zinc stearate is particularly preferably used.

  Examples of the phosphate ester-based surfactant include phosphate esters such as long-chain alkyl phosphate esters, polyoxyalkylene alkyl aryl ethers, and polyoxyalkylene alkyl ethers, but are not necessarily limited thereto. Absent.

The heat resistant slipping layer (4) having such a structure may contain fine particles for the purpose of further improving the heat resistance. In particular, the use of inorganic particles having a specific gravity of 3.0 × 10 ³ kg / m ³ or more is preferable because the inorganic particles sink into the heat-resistant slipping layer and can be prevented from falling off.

  A thermal transfer body for performing thermal transfer recording using the thermal transfer recording medium having the above-described configuration basically has a receiving layer laminated on a support. As the support, those equivalent to those used as the base film of the thermal transfer recording medium can be used, and those having mechanical strength, flexibility, heat resistance and the like are preferably used.

  Specific examples include polyesters such as polyethylene terephthalate and polyethylene naphthalate, plastic films made of polyethylene, polyvinyl chloride, polycarbonate, polyester, polysulfane, polyimide, polyvinyl alcohol, aromatic polyamide, aramid, and high-quality paper. And paper base materials such as coated paper and synthetic paper. The thickness of the support is not particularly limited, but is generally about 25 to 250 μm, more preferably about 75 to 200 μm.

  In addition, as a constituent material of the receiving layer, when a sublimable dye is contained in the heat-sensitive transfer layer of the heat-sensitive transfer recording medium, for example, butyral resin, polyethylene, polyurethane having dyeing property to the dye , Polypropylene, polyvinyl chloride, polybutadiene, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, ethylene-vinyl acetate copolymer, polyamide, polyester, polycaprolactone, polyvinyl acetal, epoxy, ketone, or modified resins thereof, Thermoplastic resins such as blended products, cross-linked products of these, and the like can be used. These may be used alone or in admixture of two or more.

  If the layer thickness of the image receiving layer is too thin, the reflection density of the thermal transfer recorded image recorded thereon is lowered, and it is difficult to ensure a sufficient density. On the other hand, if it is too thick, it tends to cause a reduction in image quality such as color bleeding. Therefore, the layer thickness is generally about 1 to 30 μm, more preferably about 3 to 10 μm. The image receiving layer preferably contains various release agents for the purpose of preventing heat fusion to the thermal transfer recording medium 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 ester-based materials, surfactants, various fillers such as metal oxides and silica can be used. Among these, it is preferable to use silicone oil. The amount of addition varies depending on the constituent conditions of the image receiving layer, but generally it is preferably about 1 to 30% by weight.

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

<Example 1>
A coating solution-1 for forming a heat-resistant slipping layer having the following composition was prepared, and the thin film was applied to one surface of a polyethylene terephthalate film having a thickness of 4.5 μm, which was a base film. Curing treatment was performed by heating for a period of time to form a heat-resistant slipping layer having a thickness of 1.0 μm.

[Coating solution-1 for forming a heat resistant slipping layer]
Polyester resin (Tg = 70 ° C.) 15 parts by weight Phosphate ester surfactant 3.0 parts by weight Tolylene diisocyanate 5.0 parts by weight Toluene 53 parts by weight Methyl ethyl ketone 24 parts by weight

  Also, a heat-sensitive sublimation transfer layer-forming coating solution-1 having the following composition was prepared, and the thin film was applied to the surface of the polyethylene terephthalate film (base film) opposite to the surface on which the heat-resistant slip layer was formed, followed by drying. Thus, a thermal transfer layer having a thickness of 1.0 μm was formed, and the thermal transfer recording medium of Example 1 was obtained.

[Thermosensitive sublimation transfer layer forming coating solution-1]
Acetal resin (average degree of polymerization about 2100, Tg about 110 ° C.) 2.5 parts by weight Acetal resin (average degree of polymerization about 600, Tg about 75 ° C.) 2.5 parts by weight C.I. I. Solvent Blue 63 5.0 parts by weight Phosphate-based surfactant 0.04 parts by weight Toluene 45 parts by weight Methyl ethyl ketone 45 parts by weight

Next, a base sheet / adhesive resin layer / coated paper (coating amount: 108 g / m ² ) / adhesive resin layer / foamed polypropylene film (thickness: 50 μm) composed of a foamed polypropylene film (thickness: 50 μm) is used. Using a laminated sheet, applying a thin film of image receiving layer ink having the following composition on one side so that the film thickness after drying is 4 μm, then drying, and then aging at 45 ° C. for 1 week As a result, a thermal transfer member with an image receiving layer was obtained.

[Image-receiving layer ink]
・ Vinyl chloride-vinyl acetate copolymer 50 parts by weight ・ Silicone oil 2 parts by weight ・ Methyl ethyl ketone 25 parts by weight ・ Toluene 25 parts by weight

<Example 2>
The two types of acetal resins in the heat-sensitive sublimation transfer layer-forming coating solution-1 are 4.0 parts by weight of an acetal resin having an average degree of polymerization of about 2100 and a Tg of about 110 ° C., an average degree of polymerization of about 600 and a Tg of about A thermal transfer recording medium of Example 2 was obtained in the same manner as in Example 1 except that the coating liquid 2 for forming a thermal sublimation transfer layer was prepared in place of 1.0 part by weight of the 75 ° C. acetal resin.

<Example 3>
The same procedure as in Example 2 was performed except that the phosphoric ester surfactant in the heat-sensitive sublimation transfer layer forming coating solution-2 was replaced with silicone oil to prepare a heat-sensitive sublimation transfer layer-forming coating solution-3. The thermal transfer recording medium of Example 3 was obtained.

<Example 4>
Example 3 was the same as Example 3 except that an acrylic polyol resin having a Tg = 72 ° C. was used in place of the polyester resin in the heat-resistant slip layer forming coating solution-1 to prepare a heat-resistant slip layer forming coating solution-2. Thus, a thermal transfer recording medium of Example 4 was obtained.

<Example 5>
Instead of 3.0 parts by weight of the phosphate ester surfactant in the coating solution-2 for forming the heat resistant slipping layer, 2.5 parts by weight of the phosphate ester surfactant and 0.5 parts by weight of stearate Was added in the same manner as in Example 4 to obtain a heat-sensitive transfer recording medium of Example 5.

<Comparative Example 1>
The two types of acetal resins in the heat-sensitive sublimation transfer layer forming coating liquid-1 are only acetal resins having an average polymerization degree of about 2100 and Tg of about 110 ° C., and the content ratio is 5.0 parts by weight. A thermal transfer recording medium of Comparative Example 1 was obtained in the same manner as Example 5 except that the forming coating solution was prepared.

<Comparative example 2>
The two types of acetal resins in the heat-sensitive sublimation transfer layer forming coating solution-1 are only acetal resins having an average polymerization degree of 600 and Tg of about 75 ° C., and the content ratio is 5.0 parts by weight. A thermal transfer recording medium of Comparative Example 2 was obtained in the same manner as in Example 5 except that the coating liquid was prepared.

<Comparative Example 3>
A thermal transfer recording medium of Comparative Example 3 was obtained in the same manner as in Example 5 except that no silicone oil was added.

<Comparative Example 4>
The coating liquid for forming a heat resistant slipping layer was prepared using an acrylic polyol resin having a Tg of 69 ° C. instead of the acrylic polyol resin having a Tg of 72 ° C. in the coating liquid for forming the heat resistant slipping layer-3. In the same manner as in Example 5, the thermal transfer recording medium of Comparative Example 4 was obtained.

<Comparative Example 5>
A heat-sensitive transfer recording medium of Comparative Example 5 was obtained in the same manner as in Example 5 except that the coating solution for forming a heat resistant slipping layer was prepared without adding the phosphate ester surfactant and the stearate.

  The thermal transfer layer surface of the obtained thermal transfer recording medium and the receiving layer surface of the above-mentioned thermal transfer member were overlapped, the dye was transferred using a thermal head, and thermal transfer recording was performed.

  The following evaluation was performed on the obtained thermal transfer image. The results are shown in Table 1.

(Evaluation criteria)
[State of base film]
◎: No tearing or tearing ○: Tearing or tearing is less than 2% (no effect on subsequent printing)
×: 2% or more torn or tearing (affects subsequent prints)
[Fusion of thermal transfer layer and transferred material]
A: No fusion (no peeling sound during printing)
○: No fusing (with peeling sound during printing)
×: Severe fusing, printing stopped (may affect subsequent printing)
[State of printed matter]
◎: Good with no defects ×: There are unevenness and streaks

  As described above, in the thermal transfer recording medium of the present invention, since the binder resin in the thermal transfer layer and the heat resistant slipping layer is as described above, it is possible to prevent the thermal transfer layer and the thermal transfer body from being fused. At the same time, since the ribbon strength at the time of thermal transfer recording is strong, good thermal transfer recording without unevenness or streak can be performed.

  On the other hand, since the thermal transfer recording medium of Comparative Example 1 uses only a resin having a large average degree of polymerization, scumming occurred on the printed matter. In addition, since the thermal transfer recording medium of Comparative Example 2 uses only a resin having a low average polymerization degree, fusion occurred between the thermal transfer layer and the thermal transfer member. Furthermore, since the thermal transfer recording medium of Comparative Example 3 did not contain silicone oil, appearance defects such as omission occurred in the printed matter. Furthermore, since the thermal transfer recording medium of Comparative Example 4 uses a thermoplastic resin having a low Tg, the base film was torn or torn, and as a result, unevenness and streaks were confirmed in the printed material. . In the thermal transfer recording medium of Comparative Example 5, since the phosphate ester surfactant and the stearate are not added, the base film is torn or torn, and accordingly, the printed matter is uneven or streaky. Was confirmed.

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

Claims (5)

A thermal transfer recording medium in which at least one heat transfer layer having at least a binder resin and a lubricant is laminated on one surface of the base film, and at least a heat resistant slip layer having at least a binder resin and a lubricant is laminated on the other surface. And the binder resin constituting the heat-sensitive transfer layer comprises a mixture of a polyvinyl acetal resin having a polymerization degree of 1100 or more and a glass transition temperature of 100 ° C. or more and a polyvinyl acetal resin having a polymerization degree of less than 1100 and a glass transition temperature of less than 100 ° C., The binder resin constituting the heat-resistant slipping layer is a reaction product of a thermoplastic resin having a glass transition temperature of 70 ° C. or higher and a polyvalent isocyanate, and the lubricant is in a weight ratio of 0.003 to 0.00 with respect to the heat- sensitive transfer layer. contained in 05, containing specific gravity 3.0 × ^{10 3} kg / ^m 3 or more inorganic particles in the heat-resistant lubricating layer Thermal transfer recording medium characterized and.   In the thermal transfer layer, a polyvinyl acetal resin having a polymerization degree of 1100 or more and a glass transition temperature of 100 ° C. or more is 60% by weight or more and 90% by weight or less, a polymerization degree of less than 1100 and a polyvinyl acetal resin having a glass transition temperature of less than 100 ° C. is 10%. 2. The thermal transfer recording medium according to claim 1, wherein the thermal transfer recording medium is contained at a ratio of from 40% to 40% by weight.   The thermal transfer recording medium according to claim 1 or 2, wherein the lubricant in the thermal transfer layer is a silicone-based lubricant.   2. The thermal transfer recording medium according to claim 1, wherein the thermoplastic resin in the heat resistant slipping layer has a reactive polyol group. The thermal transfer recording medium according to claim 1 or 4, wherein the lubricant in the heat-resistant slipping layer contains a phosphate ester surfactant and a stearate.

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