JP2009172802A - Heat transfer type image protecting film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent transfer failure of an image protecting layer to a medium to be recorded by enhancing peeling of the image protecting layer from a peeling layer. <P>SOLUTION: In the image protecting film wherein at least the thermal transferable image protecting layer 4 is arranged on a substrate 2 via the nontransferable peeling layer 3, the image protecting layer 4 peels from the peeling layer 3, and the image protecting layer 4 is affixed onto an image during thermally transferring, the softening temperature of the peeling layer 3 and the image protecting layer 4 is 40°C or more. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a thermal transfer type image protection film having a transparent image protection layer that is thermally transferred and bonded onto an image for protecting the surface of an image formed on a recording medium such as photographic paper. .

  In recent years, various printing methods such as an ink jet recording method and a sublimation type thermal transfer method using a sublimation or heat diffusible dye have been able to obtain a printed material having an image quality equivalent to that of a silver salt photograph. In particular, in the case of the sublimation type thermal transfer method, it is expected to be an alternative to silver salt photography because it can provide higher resolution than other methods, and the storage stability of images obtained by this method can be changed to silver salt photography. In order to make it closer, a transparent film for protecting an image is laminated on the image as an image protective layer.

  As a method of laminating a transparent film, various methods are performed. Recently, a thermal transfer type image protection film in which an image protection layer (transparent film) made of a thermoplastic resin is laminated on a base sheet is used, and the image protection layer of this transfer type image protection film is protected on a recording medium. A method of thermally transferring and laminating an image on an image is employed (see, for example, Patent Document 1 to Patent Document 3). In order to improve the light fastness of the image, an ultraviolet absorber, a light stabilizer and the like are usually added to the image protective layer thermally transferred onto the image.

  In addition, the image protective layer is not limited to being provided on the base sheet, but is incorporated in the ink ribbon, and by providing the image protective layer subsequent to the dye layer of the ink ribbon, the inside of the printer device using the thermal head, After the dye is thermally transferred to form an image, it is possible to continuously self-laminate an image protective layer on the formed image. In addition, an image on which the image protective layer is laminated has good storage stability due to the ultraviolet absorber and the light stabilizer blended in the image protective layer.

  By the way, the thermal transfer type image protection film is provided with a non-transferable release layer in advance on the base sheet in order to smoothly and reliably transfer onto the image protecting the image protection layer, and the thermal transferable image is formed on the release layer. A protective layer is provided. Also, when the image protection layer is incorporated into the ink ribbon, the image protection layer is provided on the base sheet of the ink ribbon via a non-transferable release layer. In such a thermal transfer type image protection film or ink ribbon, the image protection layer is peeled off at the interface with the non-transferable release layer by heating the image protection layer from the substrate sheet side with a thermal head or a heat roller. Then, it peels off from the base sheet and is smoothly transferred onto the image.

  However, in such a heat transfer type image protection film or the like, when peeling off from the non-transferable release layer and thermally transferring the image protection layer, if the temperature of the use environment becomes 30 ° C. or higher, the thermal head or heat roller In addition to heat, the temperature of the thermal transfer type image protection film and ink ribbon becomes too high depending on the temperature of the environment in use, the image protection layer and the release layer soften, and the image protection layer becomes difficult to peel from the release layer. . As a result, in a thermal transfer type image protection film or the like, the image protection layer is not thermally transferred onto the photographic paper on which the image is completely formed, causing the transfer failure such as the image protection layer floating or the image protection layer not being transferred. End up.

JP-A-60-204397 JP 59-85793 A JP 59-76298

  Therefore, the present invention provides a thermal transfer type capable of improving the peeling of the image protective layer from the non-transferable release layer and preventing the transfer failure of the image protective layer to the recording medium even when the use environment temperature becomes high. An object is to provide an image protection film.

  The thermal transfer type image protective film according to the present invention that achieves the above-mentioned object is provided with at least a thermal transferable image protective layer on a substrate via a non-transferable release layer, and the image protective layer is a release layer during thermal transfer. The image protective layer is further peeled off and bonded onto the image, and the release layer and the image protective layer have a softening point of 40 ° C. or higher.

  In the present invention, by setting the softening point of the release layer and the image protective layer to 40 ° C. or higher, even when the specified environmental temperature is 30 ° C. or higher, the release of the image protective layer from the release layer is good. It is possible to prevent occurrence of poor transfer of the layer.

  Hereinafter, a thermal transfer type image protection film to which the present invention is applied will be described in detail with reference to the drawings. The thermal transfer type image protection film 1 has a thermal transfer ink ribbon (hereinafter simply referred to as an ink ribbon) heated by a thermal head provided in the thermal transfer type printer device, and the dye of the ink ribbon is thermally transferred to a recording medium such as photographic paper. To protect the image formed. Specifically, as shown in FIG. 1, the thermal transfer type image protection film 1 is formed separately from the ink ribbon, and a non-transferable release layer 3 for improving the peelability is formed on the base sheet 2. An image protection layer 4 that is provided and thermally transferred onto the photographic paper on which an image is formed on the release layer 3 is provided. On the image protection layer 4, the photographic paper on which the image is formed and the image protection layer 4 are provided. An adhesive layer 5 for improving adhesiveness is provided. Similarly to the ink ribbon, the thermal transfer type image protection film 1 is also heated by the thermal head on the back side of the base sheet 2 where the image protection layer 4 or the like is not formed, so that the image protection layer 4 is interfaced with the release layer 3. And peeled off from the release layer 3, and the image protective layer 4 and the adhesive layer 5 are thermally transferred onto the photographic paper on which the image is formed. In the thermal transfer type image protection film 1, a heat resistant slipping layer 6 is provided on the back surface of the base sheet 2 for the purpose of preventing fusion with a thermal head during thermal transfer and improving running performance. The heat-resistant slip layer 6 may be provided as necessary.

  In the case of protecting an image with the thermal transfer type image protection film 1, the dye of the ink ribbon is diffused or melted and thermally transferred onto photographic paper to form an image, and then the adhesive layer 5 of the base sheet 2 is provided. The surface to be printed is placed on the photographic paper side, superimposed on the photographic paper, and heated and pressed by the thermal head from the back surface side of the base sheet 2 toward the photographic paper side in the superimposed state. The thermal transfer type image protection film 1 is heated and pressed from the back surface of the base sheet 2, so that the image protection layer 4 is peeled from the release layer 3 at the interface between the image protection layer 4 and the release layer 3. The adhesive layer 5 provided in the upper layer is in direct contact with the photographic paper, the adhesive layer 5 is adhered to the photographic paper, and the adhesive layer 5 is interposed between the image protective layer 4 and the image protective layer 4 is thermally transferred onto the photographic paper. Is done. Thereby, the thermal transfer type image protection film 1 bonds the image protection layer 4 on the photographic paper on which the image is formed via the adhesive layer 5, and the image protection layer 4 protects the image from light or the like.

  Specifically, various conventionally known sheet-like substrates can be used as the substrate sheet 2 of the thermal transfer type image protection film 1. For example, as the base material sheet 2, a polyester film, a polystyrene film, a polypropylene film, a polystyrene film, a polycarbonate film, a polyimide film, an aramid film, etc. are mentioned. The thickness of the base sheet 2 is not particularly limited and is usually 2 to 10 μm.

  The release layer 3 and the image protection layer 4 provided on the base sheet 2 have a softening point of 40 ° C. Thus, even when the temperature (use environment temperature) of the place where the thermal transfer type image protection film 1 is used is 30 ° C. or higher, the image protection layer 4 and the adhesive layer 5 are thermally transferred onto the photographic paper. The release from the release layer 3 of 4 is good.

  Specifically, the non-transfer release layer 3 is provided so that the image protection layer 4 is easily peeled from the base sheet 2 when the image protection layer 4 is thermally transferred onto the image. The release layer 3 can be formed of a resin having a softening point of 40 ° C. or higher, and can also have a configuration in which an ultraviolet absorber or a light stabilizer is blended in the resin. Examples of the resin having a softening point of 40 ° C. or higher include thermoplastic resins such as polyvinyl acetoacetal, polyvinyl butyral, polyurethane, and cellulose acetate butyrate. The release layer 3 may be formed of only these resins, and either or both of an ultraviolet absorber and a light stabilizer are blended in these resins, and further, a release filler or a silicone resin as necessary. It may be formed by adding various release agents such as.

  Examples of the UV absorber to be contained in the release layer 3 include triazine UV absorbers, benzotriazole UV absorbers, benzophenone UV absorbers, salicylate UV absorbers, and cyanoacrylate UV absorbers. Preferably, it is a triazine ultraviolet absorber. Since the triazine-based ultraviolet absorber has higher ultraviolet-absorbing ability than the benzotriazole-based ultraviolet absorber and the benzophenone-based ultraviolet absorber, the effect of the ultraviolet absorber can be obtained even if the content is small. Examples of the light stabilizer include hindered amine light stabilizers.

  In order to increase the softening point of the release layer 3 to 40 ° C. or higher, in addition to the method of forming the release layer 3 using only a resin having a softening point of 40 ° C. or higher, the softening point of the release layer 3 should not be lower than 40 ° C. In addition, there is a method of forming a resin having a softening point of 40 ° C. or more by containing an ultraviolet absorber or a light stabilizer. If the content of the UV absorber is too small, the effect of the UV absorber and the light stabilizer cannot be obtained. If it is too large, the UV absorber and the light stabilizer are precipitated and crystallized. The plasticization of the thermoplastic resin constituting the release layer 3 lowers the peelability of the image protection layer 4 during thermal transfer, causing transfer defects. In the case of containing an ultraviolet absorber, a triazine-based ultraviolet absorber that has a higher ultraviolet absorption capacity than a benzotriazole-based ultraviolet absorber or a benzophenone-based ultraviolet absorber and is effective in a small amount can be used to reduce the content. Since it can reduce and it can suppress more that the softening point of the peeling layer 3 falls, it is preferable to use a triazine type ultraviolet absorber.

  Such a release layer 3 can be formed by applying a coating liquid obtained by dissolving or dispersing a resin, an ultraviolet absorber, a light stabilizer or the like in a solvent on the base sheet 2 and drying it. it can. The release layer 3 is preferably about 0.1 μm to 1 μm in thickness.

  The image protection layer 4 formed on the release layer 3 is mainly composed of a thermoplastic resin. As the thermoplastic resin, a resin that can be easily peeled off from the non-transferable peeling layer 3 and can be prevented from being soiled by atmospheric gas, water, etc., and has a softening point of 40 ° C. or higher is used. Examples of the resin having a softening point of 40 ° C. or higher forming the image protective layer 4 include styrene resin, cellulose acetate butyrate resin, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral resin, polyester resin, and the like. .

  In order to improve the light resistance of the image, the image protective layer 4 is preferably blended with an ultraviolet absorber or a light stabilizer. As the ultraviolet absorber and the light stabilizer, those similar to those used for the release layer 3 can be used. In addition, you may make it mix | blend well-known additives, such as an antistatic agent.

  In order to set the softening point of the image protective layer 4 to 40 ° C. or higher, in addition to the method of forming the image protective layer 4 only with a thermoplastic resin having a softening point of 40 ° C. or higher, the softening point of the image protective layer 4 is higher than 40 ° C. However, there is a method of forming a resin having a softening point of 40 ° C. or higher by containing an ultraviolet absorber or a light stabilizer. If the content of the UV absorber is too small, the effect of the UV absorber and the light stabilizer cannot be obtained. If it is too large, the UV absorber and the light stabilizer are precipitated and crystallized. Further, due to the plasticization of the thermoplastic resin constituting the image protection layer 4, the releasability is lowered during thermal transfer, which causes a transfer failure. In the case of containing an ultraviolet absorber, a triazine-based ultraviolet absorber that has a higher ultraviolet absorption capacity than a benzotriazole-based ultraviolet absorber or a benzophenone-based ultraviolet absorber and is effective in a small amount can be used to reduce the content. It is preferable to use a triazine-based ultraviolet absorber because it can be reduced and the softening point of the image protective layer 4 can be further suppressed from decreasing.

  Such an image protection layer 4 is formed by applying a coating liquid obtained by dissolving or dispersing a thermoplastic resin, an ultraviolet absorber, a light stabilizer, or the like in a solvent on the release layer 3 and drying it. be able to. The thickness of the image protective layer 4 is appropriately determined so as not to cause the type of thermoplastic resin, edge breakage (tailing), etc. during thermal transfer, and is usually about 0.5 from the viewpoint of transferability to photographic paper. It is preferable to be about 10 μm.

  The adhesive layer 5 formed on the image protection layer 4 is mainly composed of a thermoplastic resin. As the thermoplastic resin, it is preferable to use a resin that adheres well to the photographic paper on which an image is formed by heating and pressing, for example, cellulose acetate butyrate resin, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral resin. And polyester resins.

  Since the adhesive layer 5 is thermally transferred onto the image together with the image protective layer 4, it is preferable to blend an ultraviolet absorber or a light stabilizer for the purpose of improving the light resistance of the image. In addition, you may make it mix | blend well-known additives, such as an antistatic agent. The ultraviolet absorber and the light stabilizer are preferably 40 parts or less in consideration of block king property.

  The thickness of the adhesive layer 5 is appropriately determined so as not to cause the kind of thermoplastic resin, the desired degree of adhesive strength, edge breakage (tailing), etc. during thermal transfer, and usually from the viewpoint of transferability to photographic paper. The thickness is preferably about 0.5 to 10 μm.

  The heat-resistant slip layer 6 is formed of a heat-resistant resin such as polyvinyl acetal resin, or a resin having a high softening point such as cellulose acetate or epoxy resin. In addition, a lubricant such as silicone oil, wax, fatty acid amide, and phosphate ester may be applied to or added to the heat-resistant slip layer 6, or a filler may be added. Various lubricants and antistatic agents may be added to the heat resistant slipping layer 6 in order to prevent running and sticking in the thermal transfer type printer apparatus.

  The thermal transfer type image protection film 1 having the above-described configuration is formed by applying a release layer coating liquid on a base sheet 2 by a known application method and drying to form the release layer 3, and then forming the release layer. The image protective layer coating solution is applied onto the layer 3 by a known coating method and dried to form the image protective layer 4. Then, the adhesive layer coating solution is applied onto the formed image protective layer 4. It can produce by apply | coating to the apply | coating method and drying.

  In this thermal transfer type image protection film 1, since the softening point of the release layer 3 and the image protection layer 4 is 40 ° C. or higher, the temperature of the use environment becomes 30 ° C. or higher, in addition to the heat from the thermal head. Even if the temperature of the thermal transfer type image protection film 1 itself becomes high depending on the temperature of the use environment, the release layer 3 and the image protection layer 4 are not softened, and the peeling force between the release layer 3 and the image protection layer 4 is reduced. Thus, when the image protective layer 4 is thermally transferred to the photographic paper, the image protective layer 4 peels off from the interface of the release layer 3. As a result, in this thermal transfer type image protective film 1, the image protective layer 4 is appropriately thermally transferred to the photographic paper, and the image protective layer 4 thermally transferred onto the photographic paper floats or is not thermally transferred. Can be prevented from occurring, and the image can be appropriately protected.

  Further, another thermal transfer type image protection film 10 to which the present invention is applied will be described. As shown in FIGS. 2 and 3, the thermal transfer type image protection film 10 includes a yellow dye layer 12Y, a magenta dye layer 12M, a cyan dye layer 12C, and a release layer that form an image on the same base sheet 11. An image protective layer 14 and an adhesive layer 15 are arranged side by side through the layer 13. This thermal transfer type image protection film 10 has a dye layer 12Y, 12M, 12C (hereinafter also referred to as a dye layer 12) and an image protection layer 14 formed on a base sheet 11, and the thermal transfer type image protection described above. Unlike the film 1, the dye layer 12 is not formed on the base sheet 2, and only the release layer 3, the image protection layer 4, and the adhesive layer 5 are formed.

  The thermal transfer image protection film 10 will not be described in detail with respect to the base material sheet 11, the release layer 13, the image protection layer 14, and the adhesive layer 15 having the same configuration as the thermal transfer image protection film 10 described above. Also in this thermal transfer type image protection film 10, as in the thermal transfer type image protection film 1 described above, the softening points of the release layer 13 and the image protection layer 14 are 40 ° C. or higher, so that the image protection layer 14 is printed. When the image is thermally transferred to the paper, the image protective layer 14 is peeled off at the interface with the release layer 13, and the thermal transfer of the image protective layer 14 is improved.

  The thermal transfer image protective film 10 has a yellow dye layer 12Y, a magenta dye layer 12M, a cyan dye layer 12C, the same surface as the surface on which the dye layer 12 of the base sheet 11 is formed. The image protection layer 14 is made into one unit, and a detection mark 16 for detecting this one unit is arranged next to the yellow dye layer 12Y and the image protection layer 14 side by side.

  In addition, in the thermal transfer type image protection film 10, the heat resistant slipping layer is formed on the back surface of the base sheet 11 opposite to the surface on which the dye layer 12 is provided, like the thermal transfer type image protection film 1 described above. You may have. The configuration of the heat-resistant slipping layer is the same as that of the heat-resistant slipping layer 6 of the thermal transfer type image protection film 1 described above.

  In the thermal transfer type image protection film 10, the dye layer 12 is not limited to yellow, magenta, and cyan, and may further include a black dye layer, or only an arbitrary single color dye layer. Also good.

  The dye layer 12 may be either an ink layer for sublimation type thermal transfer recording or an ink layer for thermal melting type thermal transfer recording, and may be configured in the same manner as an ink layer of a known ink ribbon. For example, in the case of an ink layer for sublimation type thermal transfer recording, for example, in the case of an ink layer for sublimation type thermal transfer recording, a cellulose resin such as methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, cellulose acetate, etc. , Polyvinyl alcohol, polyvinyl butyral, polyvinyl acetoacetal, polyvinyl acetate, polyvinyl resins such as polystyrene, and other urethane resins, etc., and those obtained by dispersing sublimable or heat diffusible dyes.

  As dyes to be included in yellow and magenta ink layers, conventionally known dyes can be used. Examples of yellow dyes include azo dyes, disazo dyes, methine dyes, styryl dyes, and pyridone / azo dyes. be able to. Examples of magenta dyes include azo dyes, anthraquinone dyes, styryl dyes, and heterocyclic azo dyes. As the cyan dye, an indoaniline dye, an anthraquinone dye, a naphthoquinone dye, a heterocyclic azo dye, or the like can be used.

  Further, in this thermal transfer type image protective film 10, even if a dye receiving layer is not formed on a recording medium such as photographic paper, the dye is thermally transferred to the recording medium so that an image can be formed satisfactorily. Prior to the transfer, the dye receiving layer is formed on the same side of the base material sheet 11 as the dye layer 12 so that the dye receiving layer can be transferred to the recording medium. You may do it.

  As the dye-receiving layer, a known dye-receiving layer having a thermal transfer property can be used, and the dye-receiving layer can be formed of a thermoplastic resin, a thermosetting resin, a UV curable resin or the like having a good dyeing property. Specifically, as the resin, polyester resin, cellulose ester resin, polycarbonate resin, polyvinyl chloride resin, polyvinyl acetate resin, polyamide resin, polyvinyl chloride resin, polystyrene resin, styrene acrylate resin, polyurethane resin, Examples include polyamide resins, urea resins, and other copolymers described above.

  The thermal transfer type image protection film 10 as described above is formed by forming a dye layer 12, a dye receiving layer, and a heat-resistant slipping layer on a base sheet 11 by a known technique, and juxtaposing with the dye layer 12 to form a release layer. The forming coating solution is applied by a known coating method, dried to form a non-transferable release layer 13, and then the image protective layer coating solution is applied onto the release layer 13 by a known coating method. The image protective layer 14 can be formed by drying, and the adhesive layer 15 can be formed by applying the adhesive layer coating solution onto the image protective layer 14 by a known coating method and drying.

  In the thermal transfer type image protection film 10 having the above-described configuration, the dye layers 12Y, 12M, and 12C of the respective colors are arranged in parallel, that is, the dye layers in the order of yellow (Y), magenta (M), and cyan (C). After the 12Y, 12M, and 12C dyes are thermally transferred onto the photographic paper to form an image, the image protective layer 14 can be subsequently thermally transferred onto the photographic paper on which the image is formed to protect the image. In this thermal transfer type image protection film 10, since the image protection layer 14 can be subsequently thermally transferred onto the image after the image is formed, the image can be easily protected.

  Moreover, since the thermal transfer type image protective film 10 has a softening point of 40 ° C. or higher as in the case of the thermal transfer type image protective film 1 described above, the temperature of the use environment is 30. Even if the temperature of the thermal transfer type image protection film 10 itself becomes high due to the temperature of the use environment in addition to the heat from the thermal head, the release layer 3 and the image protection layer 4 are not softened and the image is protected. The image protective layer 4 is peeled off from the interface of the release layer 3 when the image protection layer 4 is thermally transferred to photographic paper by making the layer 4 easy to peel off and reducing the peel force between the release layer 3 and the image protective layer 4. In addition, it is possible to prevent transfer defects of the image protection layer 4 such as the image protection layer 4 being appropriately thermally transferred to the photographic paper and being thermally transferred onto the photographic paper floating or not being thermally transferred.

  Below, the thermal transfer type image protection film to which the present invention is applied will be described with reference to examples and comparative examples.

  Examples 1 to 4 were produced as examples. In Examples 1 to 4, the non-transferable release layer forming coating liquids A and B and the image protective layer forming coating liquids A and B shown in Tables 1 to 4 below are used. As shown, a thermal transfer image protection film was prepared by combining these coating solutions.

  The softening points of the coating liquids A and B for forming a non-transferring release layer and the coating liquids A and B for forming an image protective layer in each table are those using a viscoelasticity measuring instrument (RD-1100AD) manufactured by Reska Co., Ltd. Then, glass fiber impregnated with each coating solution and dried at 120 ° C. for 1 minute were measured by the TBA method.

  Moreover, in the coating liquid B for non-transferring peeling layer formation, the ratio of the ultraviolet absorber with respect to the polyvinyl acetocetal resin is 10% by weight. In the image-protecting layer-forming coating liquids A and B, the ratio of the ultraviolet absorber to the styrene resin is 10% by weight and 20% by weight.

  Specifically, Example 1 was produced as follows. In addition, since Example 2-Example 4 were produced similarly to Example 1 except having used the coating liquid shown in Table 11, detailed description is abbreviate | omitted.

<Example 1>
In Example 1, a thermal transfer type image protection film was produced as follows. Specifically, first, as a base sheet, a polyethylene terephthalate film (trade name: Lumirror, manufactured by Toray Industries, Inc.) having a thickness of 4.5 μm is prepared, and the composition shown in Table 5 below is provided on one side of the base sheet. A heat resistant active layer was formed by applying a coating solution for a heat resistant slipping layer comprising a gravure coating method and curing it in an oven at 55 ° C. for 5 days.

  Next, on the other side of the base sheet on which the heat resistant slipping layer is formed, the coating solution A for forming the release layer having the composition shown in Table 1 is bar-coated so that the thickness when dried becomes about 1.0 μm. And dried in an oven at 120 ° C. for 1 minute to form a non-transferable release layer.

  Next, the image protective layer forming coating solution A having the composition shown in Table 3 was applied onto the release layer by bar coating so that the thickness when dried was about 1.0 μm, and dried in an oven at 120 ° C. Thus, a heat transferable image protective layer was formed.

  Next, the coating solution A for the adhesive layer having the composition shown in Table 6 below was applied onto the image protective layer by bar coating so that the thickness when dried was about 1.0 μm, and was then heated in an oven at 120 ° C. A thermal transfer image protection film was prepared by drying to form a thermal transfer adhesive layer.

  Next, for Comparative Examples, Comparative Examples 1 to 12 were prepared. In Comparative Examples 1 to 12, in addition to the non-transferable release layer forming coating liquids A and B and the image protective layer forming coating liquids A and B shown in Tables 1 to 4, the following Tables 7 to 7 are used. Using the coating liquids C and D for forming a non-transferable release layer and the coating liquids C and D for forming an image protective layer shown in Table 10, as shown in Table 11, a combination of these coating liquids is used as a thermal transfer type. An image protective film was prepared. In addition, since these Comparative Examples 1 to 12 were produced in the same manner as in Example 1 except that the coating liquid shown in Table 11 was used, detailed description thereof was omitted. Further, the softening point of the coating liquids C and D for forming the non-transferable release layer and the coating liquids C and D for forming the image protective layer is measured by the softening point of the coating liquid A for forming the non-transferring release layer. The method was the same as the method.

  Moreover, in the coating liquid D for non-transferable peeling layer formation, the ratio of the ultraviolet absorber with respect to polyvinyl acetocetal resin is 10 weight%. In the image-protecting layer-forming coating liquids C and D, the ratio of the ultraviolet absorber to the styrene resin is 40% by weight and 20% by weight.

  The transferability of the image protective layer was evaluated for the thermal transfer type image protective films of Examples and Comparative Examples produced as described above.

  The evaluation method uses an ink ribbon (UP-DR150) manufactured by Sony Corporation, the thermal transfer image protection film portion of this ink ribbon is cut out, and the thermal transfer image protection produced in the example and the comparative example is used in that portion. The film was bonded to prepare an ink ribbon provided with an ink layer (dye layer) and an image protective layer.

  The recording medium used in the test was UP-DR150 photographic paper.

  The ink ribbon was mounted on a thermal transfer type printer device (UP-DR150, manufactured by Sony Corporation) having a thermal head, and the following printing operation and image protective layer transfer were performed.

  In the printing operation, first, a black solid pattern is created using a photoshop made by Adobe on a personal computer, the data is transferred to a thermal transfer printer (UP-DR150), and a black solid is printed. Then, the image protective layer was transferred to obtain a test print sample. The printing environment at that time is 30 ° C. * 60 RH%.

  The transfer state of the image protective layer of the test print sample was as shown in Table 11 and Table 12.

  From the results shown in Table 11, in Comparative Examples 1 to 12, floating or untransferred portions were generated in the transferred image protective layer. Therefore, as in Comparative Examples 1 to 12, the softening points of the release layer and the image protective layer are both lower than 40 ° C, or the softening point of either the release layer or the image protective layer is higher than 40 ° C. If the ambient temperature is 30 ° C, in addition to the heat from the thermal head, the temperature of the image protection layer and the release layer is increased by the usage environment temperature, and the release layer and the image protection layer are softened. Thus, it was confirmed that the image protective layer was hardly peeled from the interface of the release layer, and the transferability of the image protective layer was deteriorated.

  In contrast to such a comparative example, in Example 1, the gloss of the transferred image protective layer and the adhesion to photographic paper were good. Therefore, in Example 1, the ultraviolet absorber was not contained, the release layer was formed using the release layer-forming coating liquid A having a softening point of 73 ° C., and the triazine-based ultraviolet absorber was added to the styrene resin. When the image protective layer is formed using the image protective layer forming coating solution A having a softening point of 75 ° C., both the release layer and the image protective layer have a softening point of 40 ° C. or higher. In addition to the heat from the thermal head, even when the printing environment temperature is 30 ° C. and the temperature of the release layer and the image protection layer is increased, the image protection layer and the release layer are not softened. It was confirmed that the peeling of the film was good and the transferability of the image protective layer was good.

  In Examples 2 to 4, the gloss was slightly lowered, but the adhesiveness was good and there was no problem in use. Therefore, also in Examples 2 to 4, when the softening points of the release layer and the image protective layer are both 40 ° C. or higher, the transferability of the image protective layer is maintained even when the use environment temperature is 30 ° C. Was found to be good.

  From the above, the transferability of the image protection layer is improved by setting the softening points of the release layer and the image protection layer to 40 ° C. or higher as in Examples 1 to 4.

It is sectional drawing of the image protection film to which this invention is applied. It is a top view of the other image protection film to which this invention is applied. It is sectional drawing of the image protection film.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Thermal transfer type image protective film, 2 base material, 3 peeling layer, 4 image protective layer, 5 contact bonding layer, 6 heat resistant slipping layer

Claims (7)

At least a heat transferable image protection layer is provided on a substrate via a non-transferable release layer, and the image protection layer is peeled off from the release layer during thermal transfer, and the image protection layer is bonded onto the image. In thermal transfer type image protection film
The release layer and the image protective layer have a softening point of 40 ° C. or higher.   The thermal transfer type image protection film according to claim 1, wherein the release layer contains a polyvinyl acetoacetal resin.   The thermal transfer image protection film according to claim 2, wherein the release layer further contains an ultraviolet absorber.   4. The thermal transfer type image protective film according to claim 3, wherein the ultraviolet absorber is a triazine ultraviolet absorber.   The thermal transfer image protection film according to claim 1, wherein the image protection layer contains a styrene resin.   6. The thermal transfer type image protective film according to claim 5, wherein the image protective layer further contains an ultraviolet absorber.   7. The thermal transfer type image protective film according to claim 6, wherein the ultraviolet absorber is a triazine ultraviolet absorber.

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