JP4118261B2 - Protective layer thermal transfer film - Google Patents

Description

  The present invention relates to a protective layer thermal transfer film.

  Conventionally, an image such as a gradation image, a monotonous image such as a character, a symbol, or the like is formed on a base material 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 film in which a dye layer in which a sublimable dye used as a coloring material is melted or dispersed in a binder resin is supported on a base material, and this thermal transfer film is stacked on an image receiving sheet to form a thermal head. By applying energy according to image information to a heating device such as a sublimation dye contained in the dye layer on the thermal transfer film, 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 film, and is therefore excellent in the formation of gradation images and has the advantage of easy formation of characters, symbols, etc. Have.

  However, in the gradation image and the monotone image formed by the heat-sensitive sublimation transfer method, the transferred dye is present on the surface of the transfer target, and the dye is not a pigment but a relatively low molecular weight substance. Light resistance, particularly light resistance to ultraviolet rays is inferior. For this reason, attempts have been made to improve the light resistance of images. For example, a technique has been proposed in which a protective layer containing an ultraviolet absorber is transferred to a transfer target (image receiving sheet) on which an image is formed to improve the light resistance of the image (for example, Patent Document 1).

By using the protective layer transfer sheet described in Patent Document 1, it is possible to improve the light resistance of the image, but further impart superior durability to the image (protective image) on which the protective layer is formed. It is requested. For example, when a protective image is brought into contact with a plasticizer-containing soft vinyl chloride film for a long period of time, it is desired that the image does not shift to the film and the image does not deteriorate.
JP 2000-71626 A

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a protective layer thermal transfer film excellent in light resistance and plasticizer resistance of an image formed on a transfer target.

That is, the present invention has an acrylate copolymer resin having a protective layer capable of thermal transfer on at least a part of one side of a base sheet, and the protective layer includes at least the following first to third monomers as constituent units. A protective layer thermal transfer film, characterized by comprising:
The first monomer is phenoxyethyl acrylate;
The second monomer is 2- (2′-hydroxy-5′-methacryloxyethylphenyl) -2H-benzotriazole;
The third monomer is methyl methacrylate and vinyl pyrrolidone.

  FIG. 1 shows a schematic cross-sectional view of an example of the protective layer thermal transfer film of the present invention. In the figure, the protective layer thermal transfer film 1 has a protective layer 2 formed on one surface of a substrate sheet 1.

  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 protective layer 2 provided on the base sheet is made of an acrylate copolymer resin containing the following first to third monomers as constituent units. Even if any component is missing, it is difficult to satisfy both the plasticizer resistance and the light resistance.
First monomer: phenoxyethyl acrylate;
Second monomer: 2- (2′-hydroxy-5′-methacryloxyethylphenyl) -2H-benzotriazole;
Third monomer: methyl methacrylate and vinyl pyrrolidone.

The second monomer 2- (2′-hydroxy-5′-methacryloxyethylphenyl) -2H-benzotriazole is represented by the following chemical structural formula.

  Preferred among the third monomers are methyl methacrylate, vinyl pyrrolidone, and acrylic acid.

  Moreover, it is also possible to use a 3rd monomer component in combination of 2 or more types, and the combination is a combination of methyl methacrylate and vinylpyrrolidone, acrylic acid, or acrylonitrile.

  The composition ratio of the first to third monomers constituting the acrylate copolymer resin is such that the first monomer is 5 to 50 mol%, the second monomer is 30 to 70 mol%, and the third monomer is 5 to 50 mol%. The total is 100 mol%.

  The acrylate copolymer resin constituting the protective layer is a random copolymer obtained by radical polymerization of the first to third monomer components, and has a weight average molecular weight of 10,000 to 200,000, preferably 20,000 to 120,000. Use one that has If the weight average molecular weight is too small, the film property becomes weak and a problem occurs in the plasticizer resistance. When the weight average molecular weight is too large, problems such as defective foil cutting (tailing) and a decrease in transfer sensitivity occur when used as a transfer foil. More preferably, an acrylate copolymer resin having a glass transition temperature of 40 to 80 ° C, preferably 40 to 55 ° C is used. If the glass transition temperature is too low, there will be problems such as blocking during film storage and bleeding in the storage of printed materials. If the glass transition temperature is too high, there will be problems with transfer sensitivity and plasticizer resistance due to lack of flexibility. is there. In the present invention, the weight molecular weight is a value obtained by measurement by the GPC method, and the glass transition point is a value obtained by measurement by the DSC method.

  In the protective layer of the present invention, inorganic fine particles such as silica filler, alumina filler and titanium oxide, organic fine particles such as polyethylene wax and acrylic filler, phenol-based, phosphorus-based, sulfur-based antioxidants, hindered amines, etc., as desired. You may contain additives, such as a light stabilizer, a fluorescent image whitening agent, and an ultraviolet absorber. When it contains, it is about 0.1 to 20 weight% with respect to an acrylate-type copolymer resin. If the amount is too large, the plasticizer resistance deteriorates.

  Protective layer is a reverse roll coating using gravure printing method, screen printing method, gravure plate, ink prepared by dissolving or decomposing acrylate copolymer resin and optionally other additives in solvent such as water or organic solvent. It is formed by applying and drying in accordance with a normal coating method such as a method. The thickness of the protective layer is usually about 0.1 to 5 μm, preferably about 0.5 to 3 μm.

  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 1 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, acrylonitrile-styrene copolymer; Polyamide resin; Polyvinyl toluene resin; Coumarone indene resin; Polyester resin; Polyurethane resin 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 film of the present invention is not limited to the above-described embodiment, and is a composite type protective layer thermal transfer film of a thermal transferable protective layer and a heat sublimable color material layer, a thermal transferable protective layer, and a thermal melt. It can be arbitrarily set according to the purpose of use, such as a protective layer thermal transfer film of a composite type with a colorant material layer. In the case of a composite type protective layer thermal transfer film, if a transfer material has a dye receiving layer, image formation by the thermal transfer method and transfer of the protective layer to the transfer material can be performed simultaneously.
As another example of the protective layer heat transfer film, at least one color material layer selected from the group consisting of a heat transferable protective layer, a heat sublimable color material layer, and a heat meltable color material layer is provided on one surface of the base material sheet. And a protective layer thermal transfer film in which are sequentially provided.

FIG. 2 is a schematic cross-sectional view showing another example of the protective layer thermal transfer film of the present invention. In FIG. 2, the protective layer thermal transfer film 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 base 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 the protective layer 2 described above.
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 film.
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, entrance 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, a thermal transfer recording method, or the like.

  In using the protective layer thermal transfer film of the present invention, conventionally known methods for using the protective layer thermal transfer film can be employed as they are. For example, the heat-adhesive resin layer surface of the protective layer thermal transfer film 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.

  If the protective layer thermal transfer film of the present invention is used, it is possible to impart much more excellent durability to the image formed on the transfer target. Therefore, even when the transferred body having this image is brought into contact with a film such as a soft vinyl chloride film containing a plasticizer for a long time, there is no possibility that a part of the image is transferred to the film. In addition, light resistance can be imparted to the transfer object on which the protective layer is formed.

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

Preparation of protective layer thermal transfer film (formation of protective layer constituent resin)
A protective layer constituting resin having a weight molecular weight (Mw) and a glass transition point (Tg (° C.)) shown in Table 1 is obtained by radical polymerization of the monomer composition (mol%) shown in Table 1 below in accordance with a conventional method. Prepared.

A protective layer coating solution prepared by dissolving 20 parts of the protective layer-constituting resin shown in Table 1 in 40 parts of methyl ethyl ketone and 40 parts of toluene on one surface of a 6 μm thick polyethylene terephthalate film (manufactured by Toray Industries, Inc.). Was coated by a gravi coat method (coating amount 1.5 g / m ² (during drying)) and dried to obtain protective layer thermal transfer films (Examples 1 and 2 and Comparative Examples 1 to 7).

(Manufacture of prints)
A thermal transfer film (Olympus P-400 ink ribbon) provided with yellow, magenta and cyan color material layers was used. The protective layer portion prepared above was used for the protective layer portion. Using this ink ribbon, a solid black image was formed on the image receiving paper using a sublimation transfer printer (P-400 manufactured by Olympus Corporation).

(Evaluation)
(Evaluation of plasticizer resistance)
The protective layer side of the printed matter produced above is overlaid on a plasticized soft vinyl chloride sheet (Mitsubishi Chemical Corporation, Altron # 480, thickness 400 μm), and a load of 40 g / m ² is applied at 50 ° C. The sample was stored for 24 hours in the environment of the sample, and the transfer of the dye to the vinyl chloride sheet was observed and ranked as follows. The results are summarized in Table 1.
A: No image transfer to the vinyl chloride sheet was observed;
○: Partial transfer of the image to the vinyl chloride sheet was observed;
X: Transfer of the image to the vinyl chloride sheet was observed throughout the image.

Light resistance Create a half gray solid image as described above and conduct a light resistance preservation test (Xenon Weather Meter Ci4000, 400kJ, manufactured by Atlas). Temperature and humidity in the tub (30 ° C, 20%), black panel temperature (irradiation status) Sensor panel temperature) (45 ° C.), light with a wavelength of 420 nm is irradiated at 1.2 W / m ² to an integrated energy of 400 kJ (required time: 93 hours), and the hue change before and after irradiation is visually observed. Observed and evaluated as follows.

Evaluation criteria ○: No change ×: Image degradation is understood

The typical sectional view of one embodiment of the protective layer thermal transfer film of the present invention. The typical sectional view of one embodiment of the protective layer thermal transfer film of the present invention.

Explanation of symbols

11, 21 Protective layer thermal transfer film 1, 22 Base sheet 2 Thermal transfer protective layer 27 Back layer

Claims (1)

It has a protective layer capable of thermal transfer on at least a part of one side of the substrate sheet, and the protective layer is made of an acrylate copolymer resin containing at least the following first to third monomers as constituent units. Protective layer thermal transfer film:
The first monomer is phenoxyethyl acrylate;
The second monomer is 2- (2′-hydroxy-5′-methacryloxyethylphenyl) -2H-benzotriazole;
The third monomer is methyl methacrylate and vinyl pyrrolidone.

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