JP6268925B2 - Thermal transfer sheet with protective layer - Google Patents

Description

  The present invention relates to a thermal transfer sheet, and more particularly, to a thermal transfer sheet with a protective layer, which includes a thermal transferable protective layer that is transferred so as to cover a transferred image on a transfer medium to protect the transferred image. .

  In general, a thermal transfer sheet, also called a thermal ribbon, is an ink ribbon used in a thermal transfer type printer. A thermal transfer layer is provided on one side of a substrate, and a heat resistant sliding layer is provided on the other side of the substrate. A protective layer (back coat layer) is provided. Here, the thermal transfer layer is an ink layer for sublimation (sublimation transfer method) or melting (melt transfer method) of the ink by heat generated in the thermal head of the printer, and transferring the ink to the transfer target side. It is.

  Currently, the sublimation transfer method, among thermal transfer methods, can easily form full-color images, so as printers become more sophisticated, they can be used in digital camera self-prints, cards such as identification cards, and amusement output. Widely used. Along with such diversification of applications, there is a demand for printers that are smaller and faster, that thermal transfer sheets are less expensive, and that the printed matter obtained is durable. In recent years, a thermal transfer sheet with a protective layer in which a plurality of intermediate thermal transfer layers and a protective layer for improving the durability of the printed material are provided on the same surface of the substrate has also been used.

  The protective layer can impart wear resistance, solvent resistance, chemical resistance, plasticizer resistance, and weather resistance. However, at the time of thermal transfer, the peelability of the protective layer from the substrate is required to be high. When the peelability of the protective layer from the substrate is not sufficient, the protective layer is not transferred to the transfer target, and the effect as the protective layer cannot be sufficiently exhibited. On the other hand, at the time of non-transfer, high adhesion between the protective layer and the substrate is required. If the adhesion between the protective layer and the substrate is not sufficient, the protective layer is lifted from the substrate to the non-heated area that is not thermally transferred during thermal transfer, and a part of the protective layer is peeled off on the transferred material The defect of foil dropping occurs.

  If an attempt is made to improve the peelability during thermal transfer, the adhesion during non-transfer may be reduced. On the contrary, when trying to improve the adhesion at the time of non-transfer, in the case of hot peeling to peel the protective layer from the substrate immediately after thermal transfer, or cold peeling to peel from the substrate in a state where the protective layer is cooled, The protective layer may not peel from the substrate. Thus, it is very difficult to control both peelability and adhesion.

  In order to solve such a problem, several methods have been proposed. For example, Patent Document 1 proposes a thermal transfer sheet with a protective layer in which a release layer is provided between a substrate and a release layer.

  Patent Document 2 proposes a protective layer transfer sheet comprising a laminate in which a layer mainly composed of an acrylic resin and a layer mainly composed of a polyester resin are provided in this order on a substrate.

JP 11-277899 A JP 2002-240404 A

  However, in the thermal transfer sheet with a protective layer described in Patent Document 1, since a release layer is added, the types of raw materials increase, and a process for forming the release layer is required in the manufacturing process. As a result, the manufacturing cost increases, and the thermal transfer sheet with a protective layer cannot be manufactured at a low cost. Further, in the case of the protective layer proposed in Patent Document 2, the adhesion between the layer mainly composed of acrylic resin and the layer mainly composed of polyester resin is weak, and between the acrylic resin layer and the polyester resin layer during thermal transfer. This causes the problem of easy peeling.

  In view of the above problems, an object of the present invention is to provide a thermal transfer sheet with a protective layer, which has a strong adhesion between a protective layer and a substrate during non-transfer and has a high peelability during transfer.

The thermal transfer sheet with a protective layer according to the present invention is provided with a heat-resistant slipping layer on one side of the substrate and a thermal transferable protective layer on the other side, and the thermal transferable protective layer is The release layer and the adhesive layer are laminated in this order from the substrate side. The release layer is made of a material containing at least an acrylic resin and a polyester resin, and the glass transition temperature of the polyester resin is 40 ° C. or higher and 70 ° C. or lower. , the ratio of the polyester resin Ri 0.3-2.0% by mass of the total resin weight, the adhesive layer, the number-average molecular weight and wherein Rukoto a 40000 following acrylic resin.

The coating amount after drying of the release layer is preferably 0.5 g / ^{m 2} or more 1.5 g / ^{m 2} or less.

  According to the present invention, it is possible to provide a thermal transfer sheet with a protective layer having strong adhesion between the protective layer and the substrate during non-transfer and having high transfer layer peelability during thermal transfer.

Sectional drawing of the thermal transfer sheet with a protective layer which concerns on embodiment

  FIG. 1 is a cross-sectional view of a thermal transfer sheet with a protective layer according to an embodiment. The thermal transfer sheet with a protective layer shown in FIG. 1 has a three-color dye layer (6) of a yellow layer (3), a magenta layer (4), and a cyan layer (5) on one side of the substrate (1), and is peeled off. A protective layer (9) composed of a layer (7) and an adhesive layer (8) is repeatedly provided in the longitudinal direction, and a heat resistant slipping layer (2) is provided on the other surface of the substrate (1).

  The base material (1) is required to have heat resistance and strength not to be softened and deformed by the heat pressure at the time of thermal transfer. For the base material (1), for example, synthesis of polyester, polypropylene, cellophane, polycarbonate, cellulose acetate, polyethylene, polyvinyl chloride, polystyrene, nylon, polyimide, polyvinylidene chloride, polyvinyl alcohol, fluororesin, chlorinated rubber, ionomer, etc. Resin film, condenser paper, paper such as paraffin paper and the like can be used alone or in combination. Among these, a polyethylene terephthalate film is preferable in view of physical properties, workability, cost, and the like. In addition, the thickness of the substrate (1) can be in the range of 2 μm or more and 50 μm or less in consideration of operability and workability, but in consideration of handling properties such as transfer suitability and workability, it is 2 μm. A thickness of about 9 μm or less is preferable.

  Moreover, in the base material (1), it is also possible to perform adhesion treatment on one side or / and both sides. As the adhesion treatment, known techniques such as corona treatment, flame treatment, ozone treatment, ultraviolet treatment, radiation treatment, roughening treatment, plasma treatment, primer treatment, etc. can be applied, and these treatments are used in combination. You can also

Next, as the heat-resistant slip layer (2), a conventionally known layer can be used. For example, a resin serving as a binder, a functional additive imparting releasability and slipperiness, a filler, a curing agent, a solvent, and the like. It can be formed by blending to prepare a coating solution for forming a heat resistant slipping layer, coating the prepared coating solution and drying. The coating amount after drying of the heat resistant slipping layer (2) is suitably about 0.1 g / m ² or more and 2.0 g / m ² or less. Here, the coating amount after drying of the heat resistant slipping layer (2) refers to the amount of solid content remaining after the coating liquid for forming the heat resistant slipping layer is applied and dried. Similarly, the coating amount after drying of 6) and the coating amount after drying of the release layer (7) and the adhesive layer (8) also refer to the solid content remaining after the coating solution is applied and dried.

  Next, the heat-resistant slip layer (2) is used for the thermal transfer recording on the side in contact with the thermal head for the purpose of preventing seizure of the thermal transfer recording medium to the thermal head and imparting slipperiness between the thermal head and the ink sheet. Provided on the medium. Examples of the material for the heat resistant slipping layer (2) include polyvinyl butyral resin, polyvinyl acetoacetal resin, polyester resin, vinyl chloride-vinyl acetate copolymer, polyether resin, polybutadiene resin, acrylic polyol, polyurethane acrylate, and polyester acrylate. , Polyether acrylate, epoxy acrylate, nitrocellulose resin, cellulose acetate resin, polyamide resin, polyimide resin, polyamideimide resin, polycarbonate resin, polyacrylic resin, and modified products thereof. Further, a curing agent may be used to increase heat resistance. Examples of the curing agent include isocyanates such as tolylene diisocyanate, triphenylmethane triisocyanate, tetramethylxylene diisocyanate, and derivatives thereof, but are not particularly limited.

  Next, as the dye layer (6), conventionally known ones can be used. For example, a dye layer forming coating solution is prepared by blending a heat-transferable dye, a binder, a solvent, and the like, and the prepared coating solution is applied. Then, it can be formed by drying. The dye layer (6) can be composed of a single layer of one color, or a plurality of dye layers containing dyes having different hues can be repeatedly formed on the same surface of the same substrate. The heat transferable dye is a dye that melts, diffuses, or sublimates and transfers due to heat. For example, examples of yellow components include Solvent Yellow 56, 16, 30, 93, 33, Disperse Yellow 201, 231, 33, and the like. Examples of the magenta component include C.I. I. Disperse violet 31, C.I. I. Disperse thread 60, C.I. I. Disperse violet 26, C.I. I. Solvent Red 27, or C.I. I. Solvent Red 19 etc. can be mentioned. As the cyan component, C.I. I. Disperse Blue 354, C.I. I. Solvent Blue 63, C.I. I. Solvent Blue 36, C.I. I. Solvent Blue 266, C.I. I. Disperse Blue 257 or C.I. I. Disperse Blue 24 and the like.

  As the binder contained in the dye layer (6), conventionally known binders can be used, and are not particularly limited. Cellulose resins such as ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxy cellulose, hydroxypropyl cellulose, and cellulose acetate, and polyvinyl Examples thereof include vinyl resins such as alcohol, polyvinyl acetate, polyvinyl acetal, polyvinyl pyrrolidone, and polyacrylamide, polyester resins, styrene-acrylonitrile copolymer resins, and phenoxy resins.

  Here, the blending ratio of the dye constituting the dye layer (6) and the binder is preferably a mass ratio of (dye) / (binder) = 10/100 to 300/100. If the value of (dye) / (binder) is less than 10/100, the amount of dye is too small and the color development sensitivity becomes insufficient, and a good thermal transfer image cannot be obtained. If this value exceeds 300/100, Since the solubility of the dye is extremely lowered, when it becomes a thermal transfer recording medium, the storage stability is deteriorated and the dye is likely to precipitate. The dye layer may contain known additives such as an isocyanate compound, a silane coupling agent, a dispersant, a viscosity modifier, and a stabilizer as long as the performance is not impaired.

  The protective layer (9) is required to impart durability such as plasticizer resistance to the image formed on the transfer material by the dye layer (6), and at the same time, the transfer material is processed by a process called a thermal transfer method. Need to be formed on top. Therefore, the protective layer (9) is provided between the adhesive layer (8) having adhesiveness to the transfer target, and between the adhesive layer (8) and the base material (1), and the base material (1) during thermal transfer. It is formed as a laminated body of a plurality of layers including a release layer (7) for enabling easy peeling.

  The release layer (7) is a layer formed of a material containing at least an acrylic resin and a polyester resin. As the main binder constituting the release layer (7), acrylic resins such as polymethyl methacrylate and polyethyl acrylate are suitable from the viewpoint of durability such as wear resistance and transparency, but the performance is impaired. Styrenic resins such as polystyrene and poly-α-methylstyrene, polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral, polyvinyl acetal and other vinyl resins, polyamide resins, and epoxy resins , Polyurethane resins, petroleum resins, ionomers, synthetic resins such as ethylene-acrylic acid copolymers, ethylene-acrylic acid ester copolymers, cellulose derivatives such as nitrocellulose, ethyl cellulose, cellulose acetate propionate, rosin, rosin-modified malein Acid resin, ester gum, polyi Butylene rubber, butyl rubber, styrene - butadiene rubbers, butadiene - it acrylonitrile rubber, derivatives of natural resins and synthetic rubber polychlorinated olefins such as carnauba wax, also possible to use waxes such as paraffin wax.

  When the release layer (7) is formed of a single acrylic resin, the release layer (7) is peeled off from the substrate (1) during non-transfer due to poor adhesion to the polyethylene terephthalate film as the substrate (1). There is a possibility that. Therefore, by adding a polyester resin, the adhesion of the release layer (7) during non-transfer can be enhanced. Examples of the polyester resin include crystalline polyester resins (for example, Byron (registered trademark) 200, Byron (registered trademark) 240) manufactured by Toyobo Co., Ltd., and thermoplastic saturated copolymerized polyester resins (for example, Elitel (registered trademark) manufactured by Unitika Ltd.). 3200, Eritel (registered trademark) 3203).

  In the thermal transfer sheet with a protective layer according to this embodiment, the glass transition temperature of the polyester resin used as one of the constituent materials of the release layer (7) is 40 ° C or higher and 70 ° C or lower. When the glass transition temperature is less than 40 ° C., even if a polyester resin is added, the adhesion of the release layer to the substrate during non-transfer cannot be improved. On the other hand, if the glass transition temperature is higher than 70 ° C., the release layer does not peel from the base material during the peeling at the cold, even if the peeling at the time of heating is possible.

  Furthermore, the ratio of the polyester resin is 0.3 to 2.0% by mass of the total mass of the resin. When the ratio of the polyester resin is less than 0.3% by mass, the release layer (7) does not adhere to the substrate (1) because the addition amount of the polyester resin is small. On the other hand, when the ratio of the polyester resin is more than 2.0% by mass, it is difficult to peel off in the cold, and the ratio of the polyester resin is increased, so that the plasticizer resistance which is one of durability is inferior.

The coating amount after drying of the release layer (7) is not generally limited, but is preferably 0.5 g / m ² or more and 1.5 g / m ² or less. When the thickness is less than 0.5 μm, the unevenness of the surface of the image receiving layer caused by heat at the time of image formation is noticeable in the printed matter, and there is a concern that the appearance is impaired. On the other hand, when the coating amount after drying of the release layer (7) is thicker than 1.5 μm, high energy is required for printing, and printing may be possible only with a special printer.

  In the release layer (7), silicone oil, a release agent typified by phosphate ester, a slipping agent typified by wax, an ultraviolet absorber, a light stabilizer, an antioxidant, as long as the performance is not impaired. Known additives such as fluorescent brighteners and antistatic agents can be used.

  The binder constituting the adhesive layer (8) is not particularly limited as long as it is a heat-meltable resin. As an example, polystyrene, polystyrene-polystyrene, such as poly-α-methylstyrene, polymethyl methacrylate, Acrylic resins such as polyethyl acrylate, polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymers, vinyl resins such as polyvinyl butyral, polyvinyl acetal, polyester resins, polyamide resins, epoxy resins, polyurethane resins, Synthetic resins such as petroleum resins, ionomers, ethylene-acrylic acid copolymers, ethylene-acrylic acid ester copolymers, cellulose derivatives such as nitrocellulose, ethyl cellulose, cellulose acetate propionate, rosin, rosin-modified maleic acid resin, esters Gum, polyi Butylene rubber, butyl rubber, styrene - butadiene rubber, butadiene - acrylonitrile rubbers, natural resins and synthetic rubber derivatives such as polychlorinated olefins, carnauba wax, waxes such as paraffin wax. Of these, acrylic resins are preferred from the viewpoint of adhesion to the release layer and transparency.

  The number average molecular weight of the acrylic resin is preferably 40000 or less. When the number average molecular weight exceeds 40,000, the transfer sensitivity is lowered, and the molecular weight is increased and the viscosity is increased, so that the coating suitability is deteriorated.

  The adhesive layer (8) has a release agent typified by phosphate ester, a slipping agent typified by wax, an ultraviolet absorber, a light stabilizer, an antioxidant, fluorescent whitening as long as the performance is not impaired. An agent, an antistatic agent or the like can be added.

  The heat-resistant slip layer (2), the dye layer (6), and the protective layer (9) can be formed by applying and drying by a conventionally known application method. Examples of the application method include a gravure coating method, a screen printing method, a spray coating method, and a reverse roll coating method.

  In the thermal transfer sheet with a protective layer according to this embodiment, the protective layer (9) is composed of a laminate of an adhesive layer (8) and a release layer (7). The release layer (7) is formed of a material containing at least an acrylic resin and a polyester resin, and one having a glass transition temperature of 40 ° C. or higher and 70 ° C. or lower is used as a polyester resin as one of the constituent materials. When the ratio of the resin is 0.3 to 2.0% by mass of the total mass of the resin, the adhesion between the protective layer (7) and the substrate (1) at the time of non-transfer is strong, and the heat immediately after thermal transfer A thermal transfer sheet with a protective layer having good peelability from the substrate of the protective layer can be realized in both peeling and cold peeling. Further, according to the thermal transfer sheet with a protective layer according to the present embodiment, the adhesion between the protective layer (7) and the base material (1) at the time of non-transfer, and the base material of the protective layer (7) at the time of transfer ( 1) Since it is excellent in releasability from 1), it is possible to suppress foil dropping that the protective layer (7) is peeled off from the substrate (1) to the non-heated area where heat transfer is not performed, and is peeled off on the transferred body. it can.

  Below, the material used for each Example and each comparative example of this invention is shown. In the text, “part” is based on mass unless otherwise specified.

[Preparation of substrate with heat-resistant slip layer]
As a base material, a polyethylene terephthalate film with a single-sided easy-adhesion treatment of 4.5 μm is used. It apply | coated so that an application quantity might be set to 0.5 g / m < ² >, and the base material with a heat resistant slipping layer was obtained by making it dry at 100 degreeC for 1 minute.
<Heat resistant slipping layer coating solution 1>
Silicon acrylate (Toa Gosei Co., Ltd. US-350) 50.0 parts MEK 50.0 parts

Example 1
Applying 0.7g of dry transfer yellow ink, thermal transfer magenta ink, and thermal transfer cyan ink having the following composition to the surface of the easy-adhesive surface of the substrate with a heat-resistant slip layer by gravure coating. The dye layer was formed by applying each of the coating layers to 80 / m ² and drying at 80 ° C. for 1 minute. Furthermore, the peeling layer coating solution 1 having the following composition was applied by a gravure coating method so that the coating amount after drying was 0.6 g / m ² and dried at 100 ° C. for 1 minute to form a peeling layer. did. Subsequently, an adhesive layer coating solution 1 having the following composition was applied on the formed release layer by a gravure coating method so that the coating amount after drying was 0.9 g / m ² and dried at 100 ° C. for 1 minute. Thus, an adhesive layer was formed, and a thermal transfer sheet with a protective layer according to Example 1 was produced.
<Yellow ink for thermal transfer formation>
C. I. Solvent Yellow 93 7.5 parts C.I. I. Solvent Yellow 16 2.5 parts Polyvinyl acetal resin 10.0 parts Silicone modified resin 0.2 parts Methyl ethyl ketone 53.2 parts Toluene 26.6 parts <Magenta ink for thermal transfer formation>
C. I. Disperse thread 60 5.0 parts C.I. I. Disperse Violet 26 5.0 parts Polyvinyl acetal resin 10.0 parts Silicone modified resin 0.2 part Methyl ethyl ketone 53.2 parts Toluene 26.6 parts <Cyan ink for thermal transfer formation>
C. I. Solvent Blue 63 5.0 parts C.I. I. Solvent Blue 36 5.0 parts Polyvinyl acetal resin 10.0 parts Silicone-modified resin 0.2 part Methyl ethyl ketone 53.2 parts Toluene 26.6 parts <Release layer coating solution 1>
Acrylic resin (Mitsubishi Rayon Co., Ltd. BR85) 19.9 parts Polyester resin (Toyobo Co., Ltd. Byron (registered trademark) 240 glass transition temperature_60 ° C.)
0.1 part Toluene 40.0 parts Methyl ethyl ketone 40.0 parts <Adhesive layer coating solution 1>
Acrylic resin (Mitsubishi Rayon Co., Ltd. MB2389 number average molecular weight_30000)
19.0 parts Silicone powder 1.0 part Toluene 40.0 parts Methyl ethyl ketone 40.0 parts

(Example 2)
Except that the release layer coating solution 1 was applied and dried so that the coating amount after drying of the release layer was 0.4 g / m ² , the same material and method as in Example 1 were used to obtain Example 2. A thermal transfer sheet with such a protective layer was obtained.

(Example 3)
Except that the release layer coating solution 1 was applied and dried so that the coating amount after drying of the release layer was 1.7 g / m ² , the same material and method as in Example 1 were used. A thermal transfer sheet with such a protective layer was obtained.

Example 4
A thermal transfer sheet with a protective layer according to Example 4 was obtained by the same material and method as in Example 1 except that the adhesive layer was formed using the adhesive layer coating solution 2 having the following composition.
<Adhesive layer coating solution 2>
Acrylic resin (Mitsubishi Rayon Co., Ltd. BR75 number average molecular weight_50000)
19.0 parts Silicone powder 1.0 part Toluene 40.0 parts Methyl ethyl ketone 40.0 parts

(Comparative Example 1)
A thermal transfer sheet with a protective layer according to Comparative Example 1 was obtained by the same material and method as in Example 1 except that the release layer was formed using the release layer coating solution 2 having the following composition.
<Peeling layer coating solution 2>
Acrylic resin (Mitsubishi Rayon Co., Ltd. BR85) 19.96 parts Polyester resin (Toyobo Co., Ltd. Byron (registered trademark) 240 Glass transition temperature_60 ° C.)
0.04 parts Toluene 40.0 parts Methyl ethyl ketone 40.0 parts

(Comparative Example 2)
A thermal transfer sheet with a protective layer according to Comparative Example 2 was obtained by the same material and method as in Example 1 except that the release layer was formed using the release layer coating solution 3 having the following composition.
<Release layer coating solution 3>
Acrylic resin (Mitsubishi Rayon Co., Ltd. BR85) 19.0 parts Polyester resin (Toyobo Co., Ltd. Byron (registered trademark) 240 glass transition temperature_60 ° C.)
1.0 part Toluene 40.0 parts Methyl ethyl ketone 40.0 parts

(Comparative Example 3)
A thermal transfer sheet with a protective layer according to Comparative Example 3 was obtained by the same material and method as in Example 1 except that the release layer was formed using the release layer coating solution 4 having the following composition.
<Peeling layer coating solution 4>
Acrylic resin (Mitsubishi Rayon Co., Ltd. BR85) 19.9 parts Polyester resin (Toyobo Co., Ltd. Byron (registered trademark) 300 Glass transition temperature_7 ° C)
0.1 part Toluene 40.0 parts Methyl ethyl ketone 40.0 parts

(Comparative Example 4)
A thermal transfer sheet with a protective layer according to Comparative Example 4 was obtained by the same material and method as in Example 1 except that the release layer was formed using the release layer coating solution 5 having the following composition.
<Release layer coating solution 5>
Acrylic resin (Mitsubishi Rayon Co., Ltd. BR85) 19.9 parts Polyester resin (Unitika Co., Ltd. Elitel (registered trademark) UE3690
Glass transition temperature_90 ° C.) 0.1 part Toluene 40.0 parts Methyl ethyl ketone 40.0 parts

[Preparation of transfer object]
As a base material, a foamed polyester film of 188 μm is used, and on one surface, a thermal transfer image-receiving layer coating solution having the following composition is applied by a gravure coating method so that the coating amount after drying is 5.0 g / m ^2. After applying and drying, a transfer object for thermal transfer was produced by aging in a 40 ° C. environment for 1 week.
<Image-receiving layer coating solution for thermal transfer>
Vinyl chloride-vinyl acetate-vinyl alcohol copolymer 19.5 parts Amino-modified silicone oil 0.5 part Toluene 40.0 parts Methyl ethyl ketone 40.0 parts

[Evaluation of adhesion of protective layer at room temperature]
Cellophane when the cellophane tape having a width of 18 mm and a length of 150 mm was applied to the protective layer of each of the thermal transfer sheets with protective layers of Examples 1 to 4 and Comparative Examples 1 to 4 stored at room temperature, and immediately removed. The presence or absence of adhesion of the protective layer to the tape side was visually evaluated. The evaluation was performed according to the following criteria. ○ The above is a level where there is no practical problem.
◎: Adherence of the protective layer is not recognized at all ○: Adherence of the protective layer is recognized very slightly ×: Adhesion of the protective layer is observed on the entire surface

[Evaluation of peelability of protective layer during thermal transfer]
Using the thermal transfer sheets with protective layers of Examples 1 to 4 and Comparative Examples 1 to 4 stored at room temperature, the protective layer was solid-printed on the transfer target with a thermal simulator. The printing conditions are as follows.
Printing environment: 23 ° C, 50% RH
Applied voltage: 15V
Line cycle: 0.7msec
Print density: main scanning 300 dpi sub-scanning 300 dpi

Immediately after printing under the above conditions and after 1 minute, the thermal transfer sheet with a protective layer was peeled off from the transfer target by hand, and the weight of the peeling at that time was subjected to sensory evaluation. The evaluation was performed according to the following criteria.
◎: Can be easily peeled off ○: Can be removed ×: Difficult to peel off

[Plasticizer resistance evaluation]
Using the thermal transfer sheets with protective layers of Examples 1 to 4 and Comparative Examples 1 to 4 stored at room temperature, using a thermal simulator, Y (yellow), M (magenta), C (cyan), protection The layers were sequentially solid printed to obtain a black solid print. The printing conditions were the same as the evaluation of the peelability of the protective layer during the above-described thermal transfer. Next, a plastic eraser is placed on top of the obtained black solid print, and a load of 200 g / m ² is applied to the plastic eraser and stored in an environment of 50 ° C. for 48 hours. Was observed. The evaluation was performed according to the following criteria.
○: Dye transfer is almost impossible ×: Dye transfer is almost over the entire surface

The evaluation results are shown in Table 1.

  From the results shown in Table 1, the protective layers in the thermal transfer sheets with protective layers of Examples 1 to 4 have high adhesion to the base material at room temperature, and from the base material immediately after printing at the time of thermal transfer and after 1 minute has passed. It was found that the peelability was high. Moreover, it confirmed that it was favorable also about the plasticizer resistance which is one of durability. On the other hand, since the ratio of the polyester resin is low in Comparative Example 1 and the glass transition temperature of the polyester resin is low in Comparative Example 3, the adhesiveness of the protective layer to the base material is weak, and thus the evaluation of the printing is performed. Also confirmed foil drop. In Comparative Example 2, since the ratio of the polyester resin is high, and in Comparative Example 4, the glass transition temperature of the polyester resin is high, so that the releasability during cold transfer is deteriorated, and the base material is broken at the time of peeling. did. In Comparative Example 2, it was confirmed that the plasticizer resistance also deteriorated.

  The thermal transfer sheet with a protective layer obtained by the present invention can be used in a sublimation transfer type printer, and in addition to the high speed and high functionality of the printer, various images can be easily formed in full color. Can be widely used for cards such as ID cards, amusement output, etc.

DESCRIPTION OF SYMBOLS 1 Base material 2 Heat resistant slipping layer 3 Yellow layer 4 Magenta layer 5 Cyan layer 6 Dye layer 7 Release layer 8 Adhesive layer 9 Protective layer

Claims (2)

In the thermal transfer sheet with a protective layer provided with a heat-resistant slipping layer on one side of the substrate and a thermal transferable protective layer on the other side,
The thermal transferable protective layer is formed by laminating a release layer and an adhesive layer in this order from the substrate side,
The release layer is made of a material containing at least an acrylic resin and a polyester resin,
The glass transition temperature of the polyester resin is 40 ° C. or higher and 70 ° C. or lower,
The ratio of the polyester resin Ri 0.3-2.0% by mass of the total resin weight,
The adhesive layer has a number average molecular weight and wherein Rukoto a 40000 following acrylic resin, the thermal transfer sheet with a protective layer. ^{2. The} thermal transfer sheet with a protective layer according to claim 1, wherein a coating amount of the release layer after drying is 0.5 g / m ² or more and 1.5 g / m ² or less.

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