JP4542458B2 - Protective layer thermal transfer sheet - Google Patents

Description

  The present invention relates to a protective layer thermal transfer sheet and a printed material in which the protective layer of the sheet is transferred onto an image.

  Conventionally, an image such as a gradation image, a monotonous image such as a character, a symbol, or the like is formed using a thermal transfer method. As the thermal transfer system, a thermal sublimation transfer system and a thermal melt transfer system are widely used.

  Among these, the thermal sublimation transfer method uses a thermal transfer sheet in which a dye layer in which a sublimable dye used as a coloring material is dissolved or dispersed in a binder resin is supported on a base material, and the thermal transfer sheet is superimposed on an image receiving film to form a thermal head. By applying energy corresponding to image information to a heating device such as a sublimation dye contained in the dye layer on the thermal transfer sheet, the image is formed by transferring the dye to the image receiving sheet.

  This heat-sensitive sublimation transfer method can control the amount of dye transfer in dot units according to the amount of energy applied to the thermal transfer sheet, and is therefore excellent in forming gradation images, and has the advantage of easy formation of characters, symbols, etc. Have.

  Images formed by the above heat-sensitive sublimation transfer method protect the images because the transferred dye is present on the surface of the transfer target, and also from the viewpoint of image protection such as light resistance and abrasion resistance. Many techniques for forming a protective layer are known (for example, Patent Document 1 and Patent Document 2).

Such a protective layer is required to improve “rainbow rainbow” from the viewpoint of further performance improvement in addition to the conventional required performance. Rainbow unevenness is a phenomenon that stands out when observing a printed material with a dark background color, and is a phenomenon in which rainbow-colored stripes are seen in the flow direction of printing. From the viewpoint of print quality of printed matter, it is required that such rainbow unevenness is not observed.
JP 2000-80844 A JP 2000-71626 A

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a protective layer thermal transfer sheet that can form a protective layer that does not cause rainbow unevenness without impairing the properties as a protective layer.

The present invention has a protective layer capable of thermal transfer on at least a part of one side of a base film, and the protective layer comprises three layers of a release layer, a primer layer, and a heat seal layer, and the outermost surface layer after transfer The primer layer is a primer layer, and the primer layer consists only of alumina fine particles or silica fine particles having an average primary particle size in the range of 8 to 100 nm, and the thickness of the primer layer is 0.03 to 0.5 g / characterized in that m ^2, and on the protection layer thermal transfer sheet.

  FIG. 1 shows a schematic cross-sectional view of an example of the protective layer thermal transfer sheet of the present invention. In the figure, the protective layer thermal transfer sheet 1 has a release layer 3, a primer layer 4, and a heat seal layer sequentially formed on one surface of a substrate sheet 2. In the case of the configuration of FIG. 1, the protective layer has a three-layer configuration of a release layer, a primer layer, and a heat seal layer.

  The base material sheet 1 can be the same base material sheet widely used in this field, and is not particularly limited. Specific examples of the base sheet include polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polyphenylene sulfide, polyether ketone, polyether sulfone, and other highly heat-resistant polyesters; polypropylene, polycarbonate, cellulose acetate, polyethylene derivatives, Examples thereof include plastic films such as polyvinyl chloride, polyvinylidene chloride, polystyrene, polyamide, polyimide, polymethylpentene, and ionomer, and laminates thereof. The plastic film may be stretched or unstretched. Although the thickness of a base material sheet can be suitably selected in consideration of strength, heat resistance and the like, it is usually about 1 to 100 μm.

  The release layer 3 is made of a binder resin. As the binder resin, known thermoplastic resins and thermosetting resins used in this field can be widely used.

  Examples of the thermoplastic resin include acrylic resins such as polymethacrylic acid, polymethacrylamide, polymethyl methacrylate, polyethyl methacrylate, polybutyl acrylate; polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, polyvinyl Examples thereof include vinyl resins such as alcohol and polyvinyl butyral; cellulose derivatives such as ethyl cellulose, nitrocellulose, and cellulose acetate.

Examples of the thermosetting resin include unsaturated polyester resins, polyester resins, polyurethane resins, amino alkyd resins, and the like. These binder resins may be used alone or in combination of two or more.
Among these binder resins, acrylic resins are preferable.

The release layer may contain a wax together with the binder resin. When the wax is contained, the scratch resistance and foil breakability of the release layer are improved.
Examples of the wax include polyethylene wax, polyester wax, polystyrene powder, olefin powder, microcrystalline wax, carnauba wax, paraffin wax, Fischer-Tropsch wax, various low molecular weight polyethylene, wood wax, beeswax, whale wax, wool wax, Examples include shellac wax, candelilla wax, petrolactam, partially modified wax, fatty acid ester, and fatty acid amide.

  Wax is usually contained in the release layer in an amount of about 0.1 to 30% by weight, preferably about 0.1 to 10% by weight.

  In the present invention, the release layer may contain an ultraviolet absorber. By blending the ultraviolet absorber, it is possible to improve the light resistance and weather resistance of the image of the transferred material covered with the protective layer after being transferred.

  As the ultraviolet absorber, conventionally known organic ultraviolet absorbers such as salicylate, benzophenone, benzotriazole, substituted acrylonitrile, nickel chelate, hindered amine and the like can be widely used. Also, for example, addition polymerizable double bonds such as vinyl groups, acryloyl groups, and methacryloyl groups, or functional groups such as alcoholic hydroxyl groups, amino groups, carboxyl groups, epoxy groups, and isocyanate groups are introduced into these ultraviolet absorbers. An ultraviolet absorbing resin may be contained in the release layer.

Furthermore, you may contain various additives, such as antioxidant and a fluorescent whitening agent, in the said peeling layer. The release layer is a gravure printing method, a screen printing method, which is obtained by adding a necessary additive such as wax to the binder resin and dissolving or dispersing in water, an organic solvent or the like on the binder resin. It is formed by applying and drying according to a normal coating method such as a reverse roll coating method using a gravure plate.
The thickness of the release layer is usually about 0.1 to 10 μm, preferably about 0.5 to 5 μm.

  In this invention, you may provide a release layer further between the peeling layer 3 and the base material sheet 2 as needed.

  When the peelability between the base sheet and the protective layer is not appropriate, the release layer is provided in order to adjust the adhesiveness between the base sheet and the protective layer and to satisfactorily peel the protective layer.

  The release layer is, for example, various waxes such as silicone wax, silicone resin, fluororesin, acrylic resin, water-soluble resin, cellulose derivative resin, urethane resin, acetic acid vinyl resin, acrylic vinyl ether resin, maleic anhydride resin. It is comprised from various resins etc., such as these, and these mixtures.

The release layer can be formed by applying a coating liquid containing at least one selected from the group consisting of the above waxes and the above resin onto a base sheet according to a conventionally known coating method and drying. . The thickness of the release layer is usually about 0.5 to 5.0 μm.
When the release layer is provided, it is desirable that the thermal transfer resin layer is peeled off from the release layer by transfer, and the release layer itself is formed so as to remain on the substrate sheet side.

  In the case of the thermal transfer sheet having the configuration shown in FIG. 1 provided with a primer layer, the primer layer is a layer adjacent to the outermost surface layer after transfer of the protective layer. In the thermal transfer sheet having such a configuration, the primer layer is formed of fine particles having an average primary particle size in the range of 10 to 100 nm. The primer layer contributes to the function as a protective layer in which rainbow unevenness does not occur. )

  The fine particles may be either inorganic fine particles or organic fine particles as long as they are colorless or white. From the viewpoint of particle hardness and heat resistance, inorganic fine particles are preferred. In the present invention, the term “colorless or white” means that transparency is not impaired when provided as a coating film. Use of fine particles that are not colorless or white is not preferable because the coating film is colored and the image is colored like a background fog.

  Silica, alumina, titania, calcium carbonate, etc. can be used as the inorganic fine particles. Silica and alumina are preferably used.

  As the organic fine particles, styrene fine particles, acrylic fine particles, melamine resin fine particles and the like having a heat resistant temperature of 80 ° C. or higher, preferably 120 ° C. or higher are used. When organic fine particles having a heat-resistant temperature lower than 80 ° C. are used, the particles are deformed by heat and pressure during printing, and there is a problem that irregularities at the original interface cannot be maintained. The heat-resistant temperature of the particle is the maximum temperature that the particle can withstand without being broken or crushed by heat. In the present invention, the heat-resistant temperature is measured by a thermal stress strain measuring device (TMA) (manufactured by Seiko Electronics Co., Ltd.). ing. However, as long as it can be measured by the same principle and method, it can be measured without being limited to the left device.

  Fine particles having an average primary particle size of 8 to 100 nm, preferably 8 to 80 nm, more preferably 10 to 70 nm are used. If the average primary particle size is too small, the effect of preventing rainbow unevenness cannot be seen. On the other hand, if it is too large, the transparency of the protective layer is impaired. In the present invention, the “average primary particle size” is a value measured by the BET method.

  In addition to the primer layer, additives such as leveling agents, antifoaming agents, fluorescent whitening agents, UV absorbers, etc. are added in an amount of about 0.01 to 5% by weight based on the total weight of the primer layer. May be.

The primer layer is formed by applying a coating solution prepared by dissolving or dispersing fine particles and, if necessary, other additives in a solvent such as an organic solvent or water, on the release layer by a known coating method such as a wire coating method. It is formed by drying. The thickness of the primer layer is about 0.03 to 1 g / m ² , preferably about 0.03 to 0.5 g / m ² . If the primer layer is too thick, transparency will be impaired, and if it is too thin, the effect of preventing rainbow unevenness will not be seen.

  When the primer layer comprising fine particles is observed after production, it is observed as being contained in the resin constituting the heat seal layer described below, and is not observed independently as a fine particle layer. In the present invention, for the sake of convenience, a group of fine particles formed by applying and drying fine particles on the layer previously formed in the production process, in the structure of FIG. 1, on the release layer is called a primer layer.

  The heat seal layer plays a role of adhesion of the protective layer to the image surface. As the resin constituting the heat seal layer, any resin containing a conventionally known pressure-sensitive adhesive, heat-sensitive adhesive and the like can be used, but a glass transition temperature (Tg) of 50 to 80 ° C. is thermoplastic. A resin is preferred. Specific examples of such thermoplastic resins include polyester resins, vinyl chloride-vinyl acetate copolymer resins, acrylic resins, butyral resins, epoxy resins, polyamide resins, vinyl chloride resins, and the like. The heat seal layer may contain additives such as an ultraviolet absorber, an antioxidant, and a fluorescent brightening agent.

  The heat seal layer is formed by applying a coating solution obtained by dissolving or dispersing the above resin and other additives in a solvent such as an organic solvent on the primer layer by a known coating method such as a wire coating method, curing, and drying. Is formed. The thickness of the heat seal layer is usually about 0.1 to 10 μm, preferably about 0.5 to 5 μm.

  The protective layer in the protective layer thermal transfer sheet of the present invention is formed to have a transmittance of 95% or more, preferably 98% or more. When the transmittance is lower than 95%, there arises a problem that the concentration of the dye printed on the base of the protective layer appears to be thin. In this invention, the transmittance | permeability uses the transmittance | permeability in the wavelength range of 500-600 nm with a spectrophotometer.

  In the present invention, an interlayer adhesive layer different from the durable layer, the ultraviolet absorbing layer, and the fine particle layer may be further provided as necessary before forming the heat seal layer.

  In the present invention, a back layer may be formed on the other surface of the base sheet. The back layer is provided for the purpose of preventing thermal fusion between a heating device such as a thermal head and the base sheet 2 and smooth running. Examples of the resin used for the back layer include cellulose resins such as ethyl cellulose, hydroxy cellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate, cellulose butyrate, and nitrocellulose; polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl acetal, polyvinyl Vinyl resins such as pyrrolidone; Acrylic resins such as polymethyl methacrylate, polyethyl acrylate, polyacrylamide, and acrylonitrile-styrene copolymers; polyamide resins; polyvinyl toluene resins; coumarone indene resins; polyester resins; A simple substance or a mixture of natural or synthetic resins such as silicone-modified or fluorine-modified urethane is used. Of the above resins, a resin having a hydroxyl group reactive group (for example, butyral resin, acetal resin, etc.) is used in order to further increase the heat resistance of the back layer, and polyisocyanate is used in combination as a crosslinking agent. Thus, a crosslinked resin layer is preferable.

  Further, in order to impart slidability with the thermal head, a solid or liquid release agent or lubricant may be added to the back layer to provide heat-resistant lubricity. Examples of release agents or lubricants include various waxes such as polyethylene wax and paraffin wax; higher aliphatic alcohols, organopolysiloxanes, anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants Various surfactants such as an activator and a fluorine-based surfactant; fine particles of inorganic compounds such as organic carboxylic acids and derivatives thereof, fluorine-based resins, silicone-based resins, talc, and silica can be used. The amount of lubricant contained in the back layer is about 5 to 50% by weight, preferably about 10 to 30% by weight in the back surface.

  The back layer is a gravure printing method, a screen printing method, a reverse coating method using a gravure plate, or the like obtained by dissolving or dispersing the above resin and other additives in a solvent such as water or an organic solvent on a base sheet. It is formed by applying and drying according to the usual coating method. The thickness of the back layer is usually about 0.1 to 10 μm, preferably about 0.5 to 5 μm.

The protective layer thermal transfer sheet of the present invention is not limited to the above-mentioned embodiment, and is a composite type protective layer thermal transfer sheet of a thermal transferable protective layer and a heat sublimable colorant layer, a thermal transferable protective layer and a thermal melt. It can be arbitrarily set according to the purpose of use, such as a composite type protective layer thermal transfer sheet with a colorant material layer. In the case of the former composite type protective layer thermal transfer sheet, as long as it has a dye receiving layer as a transfer target, image formation by the thermal transfer method and transfer of the protective layer to the transfer target can be performed simultaneously. .
As an example of the protective layer heat transfer sheet, at least one color material layer selected from the group consisting of a heat transferable protective layer, a heat sublimation color material layer, and a heat meltable color material layer is provided on one surface of the base sheet. A protective layer thermal transfer sheet and the like that are sequentially provided can be exemplified.

FIG. 2 is a schematic cross-sectional view showing another example of the protective layer thermal transfer sheet of the present invention. In FIG. 2, the protective layer thermal transfer sheet 21 of the present invention has a heat sublimable color material layer Y, a heat sublimation color material layer M, a heat sublimation color material layer C, a heat sublimation property on one surface of a substrate sheet 22. The color material layer B and the heat transferable protective layer 26 are formed in the surface order, and the back layer 27 is formed on the other surface of the base sheet 22. The heat transferable protective layer 26 includes, for example, a release layer 23, a primer layer 24, and a heat seal layer 25.
The heat-sublimable color material layers Y, M, C, and B in FIG. 2 may be heat-meltable color material layers Y, M, C, and B, and are configured by mixing these layers. Also good.

There is no restriction | limiting in particular as a to-be-transferred body which transfers a protective layer using this invention protective layer thermal transfer sheet.
The transfer target may be, for example, a sheet made of any base material such as plain paper, high-quality paper, tracing paper, and plastic film. Further, the transfer object may have any shape such as a card, a postcard, a passport, a notepaper, a report sheet, a notebook, a catalog, and the like.

  Specific examples of the transfer object of the present invention include, for example, stock certificates, securities, certificates, passbooks, boarding tickets, car horse tickets, stamps, stamps, appreciation tickets, admission tickets, tickets, etc .; cash cards, credit cards , Prepaid cards, members cards, greeting cards, postcards, business cards, driver's licenses, IC cards, optical cards, etc .; cartons, cases such as containers; bags: forms, envelopes, tags, OHP sheets, slide films , Bookmarks, calendars, posters, brochures, menus, passports, POP supplies, coasters, tisplays, nameplates, keyboards, cosmetics, watches, lighters and other accessories; stationery, report paper and other stationery; building materials, panels, emblems, Keys, cloth, clothing, footwear, radio, TV, calculator, OA equipment, etc., each Sample book, mention may be made of the album, the output of computer graphics, the medical image output, and the like.

  The image on the transfer medium may be formed by any method such as an electrophotographic method, an ink jet recording method, or a thermal transfer recording method.

  The heat sublimable color material layer is formed by, for example, supporting a binder resin with a dye that transfers heat mainly by sublimation.

  As the dye, any of the conventionally used dyes used in thermal transfer sheets can be used effectively, and is not particularly limited. Preferable dyes include magenta dyes such as MS Red G, Macrolex Red Violet R, Ceres Red 7B, Samaron Red HBSL, Resolin Red F3BS, and the like. Examples of yellow dyes include Holon Brilliant Yellow 6GL, PTY-52, Macrolex Yellow 6G, and the like. Examples of the cyan dye include Kayaset Blue 714, Waxoline Blue AP-FW, Holon Brilliant Blue S-R, MS Blue 100, and the like.

  Any conventionally known binder resin for supporting the dye can be used. Examples of preferred binder resins include cellulose resins such as ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxy cellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate, cellulose butyrate; polyvinyl alcohol, polyvinyl acetate, polyvinyl petital, polyvinyl acetal, polyvinyl pyrrolidone. And vinyl resins such as polyacrylamide; polyester resins and the like. Of these, cellulose resins, polyvinyl resins such as polyvinyl butyral and polyvinyl acetal, and polyester resins are preferred from the viewpoints of heat resistance, dye transferability, and the like.

  Furthermore, conventionally well-known various additives may be mix | blended in the heat sublimable color material layer as needed.

  The content of the dye is usually about 5 to 90% by weight, preferably about 10 to 70% by weight, based on the total amount of the heat sublimable color material layer.

  The heat sublimable color material layer is preferably formed by adding the sublimation dye, binder resin and other optional components in an appropriate solvent, and dissolving or dispersing each component to form a heat sublimable color material layer forming paint. Alternatively, it is carried out by preparing an ink, applying it surface-sequentially on the substrate sheet and drying it.

  The thickness of the heat sublimable color material layer is usually about 0.2 to 5 μm, preferably about 0.4 to 2 μm.

The heat-meltable color material layer is obtained by loading a colorant on a binder.
As the colorant, among organic or inorganic pigments and dyes, those having good characteristics as a recording material, for example, those having a sufficient color density and not browned by light, heat, temperature or the like are preferable. As such a colorant, for example, those having a hue such as black, cyan, magenta, and yellow are used.

  As the binder, for example, a mixture in which drying oil, resin, mineral oil, cellulose derivatives, rubber derivatives and the like are blended as a main component of the wax is used.

  Examples of the wax include microcrystalline wax, carnauba wax, paraffin wax, Fischer-Tropsch wax, various low molecular weight polyethylene, wood wax, beeswax, whale wax, ibota wax, wool wax, shellac wax, candelilla wax, petrolactam, polyester wax. Various waxes such as partially modified waxes, fatty acid esters, and fatty acid amides are used.

  Further, vinyl chloride / vinyl acetate copolymer resin, acrylic resin, chlorinated rubber, vinyl chloride / vinyl acetate copolymer resin, cellulosic resin, and the like can be used as a bander.

The formation of the heat-meltable color material layer is carried out by preparing a composition for forming a heat-meltable color material layer to which the colorant, binder resin, and other additives as necessary are added, and applying this to the above base sheet. Further, it is carried out by applying a hot melt coat, a hot lacquer coat, a gravure coat, a gravure reverse coat, a knife coat, an air coat, a roll coat method, and the like, followed by drying.
The thickness of the heat-meltable color material layer is usually about 0.1 to 8 μm, preferably about 0.4 to 2 μm.
The hot-melt colorant layer formed on the base sheet may consist of one layer, or may consist of two or more layers.

  In the present invention, a primer layer may be provided between the base sheet and the heat sublimable color material layer. Moreover, in this invention, the peeling layer may be provided between the base material sheet and the heat-meltable color material layer. This release layer may be the same as the release layer described above.

  In using the protective layer thermal transfer sheet of the present invention, conventionally known methods of using the protective layer thermal transfer sheet can be employed as they are. For example, the heat seal layer surface of the protective layer thermal transfer sheet of the present invention may be superposed on the transfer target, and the thermal transfer resin layer may be thermally transferred onto the transfer target.

(The invention's effect)
The protective layer thermal transfer sheet of the present invention can give a printed material a protective layer that does not cause rainbow unevenness without impairing the properties of the protective layer.

  The following examples illustrate the invention. In the examples, “parts” or “%” are based on mass unless otherwise specified.

The products used in this example are briefly summarized below.
Dianal BR-87: Polymethylmethacrylic acid (PMMA), manufactured by Mitsubishi Rayon Co., Ltd., Mw: 25000
AL200: Alumina sol (Alumina average particle size 20 nm, manufactured by Nissan Chemical Industries, Ltd.) (solid content 10% by weight)
Aluminum sol 10: Alumina sol (Alumina average particle size 10 nm, manufactured by Nissan Chemical Industries, Ltd.) (solid content 10% by weight)
Snowtex OS: Colloidal silica (silica average particle size 10 nm, manufactured by Nissan Chemical Industries, Ltd.) (solid content 20% by weight)
Snowtex 2OL: colloidal silica (silica average particle diameter 20 nm, manufactured by Nissan Chemical Industries, Ltd.) (solid content 20% by weight)
Snowtex OYL: colloidal silica (silica average particle size 70 nm, manufactured by Nissan Chemical Industries, Ltd.) (solid content 20% by weight)
Snowtex OXS: colloidal silica (silica average particle size 5 nm, manufactured by Nissan Chemical Industries, Ltd.) (solid content 20% by weight)
Snowtex MP4540: colloidal silica (silica average particle diameter 450 nm, manufactured by Nissan Chemical Industries, Ltd.) (solid content 20% by weight)
Byron 700: Polyester, manufactured by Toyobo Co., Ltd., Mn: 9000
Tinuvin 900: UVA compound, manufactured by Ciba Specialty Chemicals
UVA stands for “ULTRA-VIOLET LIGHT ABSORBER”.
Silicia 310P: Silica filler, manufactured by Fuji Silysia Co., Ltd., average particle size of 3 μm

Preparation of protective layer thermal transfer sheet (ribbon) (Examples 1-7, Comparative Examples 1-5)
First layer (peeling layer)
20 parts of Dianal BR-87, 40 parts of toluene and 40 parts of methyl ethyl ketone were mixed to prepare a release layer ink. The first layer of the obtained ink was applied to a PET film having a thickness of 4.5 μm with a wire coater bar (# 3) so that the application amount was 1.0 g / m ² . The obtained coated film was dried in an oven at 110 ° C. for 1 minute.

Second layer (primer layer)
The material shown in Table 1 was diluted with the primer dilution solvent shown in Table 1 so that the solid content would be 3% to prepare a primer layer ink. The obtained ink was apply | coated to PET film which apply | coated the 1st layer so that it might become the application quantity (0.2g / m < ² >) described in Table 1 with the wire coater bar (# 3). The obtained coated film was dried in an oven at 110 ° C. for 1 minute. In addition, the denatured ethanol described in Table 1 is industrial ethanol to which a certain amount of methanol is added.

Third layer (heat seal layer (HS) layer)
Byron 700: 23.5 parts, Tinuvin 900: 6 parts, Silicia 310P: 0.5 parts, Toluene: 35 parts, Methyl ethyl ketone: 35 parts were mixed to prepare an ink for heat seal layer. The obtained ink was apply | coated to PET film which apply | coated the 2nd layer so that it might become a coating amount of 1.0 g / m < ² > with a wire coater bar (# 4). The obtained coated film was dried in an oven at 110 ° C. for 1 minute.

Rainbow irregularities were evaluated for the protective layer thermal transfer sheets obtained in Examples 1 to 7 and Comparative Examples 1 to 5, and the results are summarized in Table 1.
In Comparative Example 3, the protective layer thermal transfer sheet could not be produced because repelling occurred when the primer layer was formed.

Evaluation Rainbow rainbow rainbow unevenness was evaluated by printing a black solid on the protective layer ribbon created as described above with Megapixel III (Altec's sublimation transfer printer) and visually checking the printed matter. Ranked. The results are summarized in Table 1.
○: No rainbow unevenness when observed under fluorescent light ×: Rainbow unevenness is observed when observed under fluorescent light

Light resistance Light resistance is obtained by printing an actual image with the above printer and covering a portion corresponding to half the area of the image with aluminum foil. The sample was irradiated with light with a light resistance tester (Waters Meter Ci4000 manufactured by Atlas Co., Ltd.) until the light in the wavelength range of 420 nm reached an integrated value of 200 kJ.

  After storage, the aluminum foil of the sample was removed, the degree of photobleaching was visually confirmed, compared with the sample without the primer (sample of Comparative Example 1), and ranked as follows. The results are summarized in Table 1.

○: Difference in fading is less than or equal to ×: Difference is large

Plasticizer resistance The sample printed by the printer is overlapped with a soft vinyl chloride sheet, and stored under a 50 ° C. environment for 48 hours under a load of 40 g / cm ² . The degree of migration of the dye to the vinyl chloride sheet side was visually confirmed, compared with a sample without a primer (sample of Comparative Example 1), and ranked as follows. The results are summarized in Table 1.

○: PVC sheet is not contaminated ×: PVC sheet is contaminated with dye

The typical sectional view of one embodiment of the protection layer thermal transfer sheet of the present invention. The typical sectional view of one embodiment of the protection layer thermal transfer sheet of the present invention.

Explanation of symbols

1,21 Protective layer thermal transfer sheet 2,22 Base sheet 3,23 Release layer 4,24 Primer layer 5,25 Heat seal layer 26 Thermal transfer protective layer 27 Back layer

Claims (4)

Having a protective layer capable of thermal transfer on at least a part of one side of the base film,
The protective layer is composed of three layers, a release layer, a primer layer, and a heat seal layer, the layer adjacent to the outermost surface layer after transfer is a primer layer, and the primer layer has an average primary particle size in the range of 8 to 100 nm. A protective layer thermal transfer sheet comprising only the alumina fine particles or silica fine particles and the primer layer having a thickness of 0.03 to 0.5 g / m ² .   The protective layer thermal transfer sheet according to claim 1, wherein the fine particles are white.   The protective layer thermal transfer sheet according to claim 1, wherein the transmittance of the protective layer is 95% or more.   A printed matter to which the protective layer of the protective layer thermal transfer sheet according to claim 1 is transferred.

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