JP2854319B2 - Image receiving sheet for thermal transfer recording - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer recording image-receiving sheet used for recording by transferring a sublimable dye or the like of a thermal transfer sheet in thermal transfer recording such as a thermal printer. .

[Prior Art] As a conventional image transfer sheet for thermal transfer recording, a sheet provided with a coating layer of a saturated polyester resin or the like on the surface of synthetic paper is known, and this type of image transfer sheet for thermal transfer recording is made of polyethylene terephthalate or the like. Is used in combination with a thermal transfer sheet comprising a sublimable dye and a binder on the surface of the thermal transfer sheet and the receiving layer are overlapped with each other so that the thermal transfer layer and the receptor layer are in contact with each other. Attempts have been made to form a natural color photographic image or the like by heating by a point-like heat-sensitive means such as a thermal head that generates heat under control to transfer the sublimable dye in the thermal transfer layer to the receiving layer.

However, when the thermal transfer recording image-receiving sheet is made of synthetic paper using a resin having low heat resistance such as a polyolefin resin as a base material, distortion is left on the synthetic paper due to heat generated by heating at the time of image formation, and an image is formed. The formed thermal transfer recording image receiving sheet curls. Further, even when synthetic paper using a resin having high heat resistance is used as the base material, a sufficient print density could not be obtained due to poor cushioning properties and heat insulation properties of the base material.

Various efforts have been made in the past to remedy these drawbacks.

For example, Japanese Patent Application Laid-Open No. 62-198497 proposes an image-receiving sheet for thermal transfer recording in which synthetic paper is attached to at least one side of a core material. Although the curl of the thermal transfer recording image-receiving sheet after image formation is improved by this proposal, there is a problem such as image transfer omission because the smoothness of the sheet is inferior to that of a sheet of synthetic paper alone. Further, US Pat. No. 4,774,224 proposes using resin-coated paper having a small Ra for an image receiving sheet for thermal transfer recording. Although the curl of the thermal transfer recording image receiving sheet after image formation was improved by this proposal, sufficient print density was obtained because the heat insulation properties of the sheet were inferior to those of the thermal transfer recording image receiving sheet using synthetic paper. There was a problem that it was not possible.

[Problems to be Solved by the Invention] The present invention solves the above problems, namely, curl after printing,
An object of the present invention is to provide an image receiving sheet for thermal transfer recording that does not have problems such as a decrease in print density and transfer omission.

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above problems, and as a result, at least one surface of the base paper contains a layer containing polymer microspheres composed of particles having a different phase structure, a resin, It has been found that the object of the present invention is achieved by laminating a layer and a sublimable dye-receiving layer in this order.

[Function] In the present invention, as the polymer microsphere used, heterophasic structured particles meet the object of the present invention.

Heterophase particles are prepared by a seed emulsion polymerization method.
It is a composite polymer emulsion particle in which two or more kinds of polymer molecules coexist in the particle, and has a form such as gold rice sugar, a snowman, a wild strawberry, and a star. Specifically, monomer B is seed-emulsion-polymerized therein using polymer A particles prepared by emulsion polymerization as seeds, thereby finally producing A / B composite particles composed of two types of polymer molecules. is there. The heterogeneous polymers form a heterophase structure in which phases are separated. Examples of the hetero-phase structure particles include a polyethyl acrylate-polystyrene copolymer resin, a polybutyl acrylate-polystyrene copolymer resin, and a polymethyl methacrylate-polystyrene copolymer resin.

In the present invention, the particle diameter of the polymer microsphere comprising these hetero-phase structured particles is 10 μm or less in outer diameter, preferably 5 μm or less, more preferably 3 μm or less.

In the present invention, the layer containing the polymer microspheres composed of the hetero-phase structured particles may be a single layer, but a layer composed of a combination of the polymer microspheres and an appropriate binder is preferable. The mixing weight ratio of the polymer microspheres composed of the hetero-phase structured particles and the binder is 5 to 150 parts by weight, preferably 10 to 50 parts by weight, based on 100 parts by weight of the polymer microspheres.

If necessary, an inorganic pigment and an organic pigment (not hollow resin particles) may be used in the layer containing the polymer microspheres comprising the hetero-phase structured particles of the present invention. Specifically, as inorganic pigments, clay, talc, calcium carbonate, calcium sulfate, barium sulfate, titanium oxide, zinc oxide, satin white, silicon oxide, zeolite, magnesium hydroxide, alumina, synthetic silica, calcium silicate, silica Sodium earth, aluminum hydroxide, etc., and organic pigments such as polyethylene, porstyrene, polyester, urea
Formalin resin, polyamide resin and the like.

In the present invention, as the binder used in the layer containing the polymer microspheres composed of the hetero-phase structure particles, a water-soluble polymer, a synthetic resin latex, a resin soluble in an organic solvent, a resin curable by ultraviolet light or electron beam, or the like. Can be used.

Examples of the water-soluble polymer include starches such as oxidized starch, etherified starch, dextrin, phosphated starch, carboxymethylcellulose, cellulose derivatives such as hydroxymethylcellulose, casein, gelatin,
Polyvinyl alcohol and its derivatives, maleic anhydride resins, copolymers of two or more components of maleic anhydride with ethylene, styrene, isobutadiene, vinyl acetate and the like are used.

As the synthetic resin latex, styrene-butadiene copolymer, conjugated diene-based polymer latex such as methyl methacrylate-butadiene copolymer, acrylic polymer latex such as acrylate and methacrylate polymer or copolymer, A vinyl polymer latex such as an ethylene-vinyl acetate copolymer, or a functional group-modified polymer latex of a functional group-containing monomer such as a carboxyl group of these various polymers is used. As an organic solvent-soluble resin, polyacrylonitrile, polyvinyl chloride, polyvinyl acetate, melamine resin, phenol resin, polyurethane, polyamide, alkyd resin and the like are used.

Examples of the resin that is cured by ultraviolet light or electron beam include a resin having a C ＝ C unsaturated bond such as an acryloyl group or a methacryloyl group on a molecular side chain or a molecular terminal. Typical examples thereof include ester acrylate, ester methacrylate, epoxy acrylate, epoxy methacrylate, urethane acrylate, urethane methacrylate, monofunctional acrylate, monofunctional methacrylate, polyfunctional acrylate, and polyfunctional methacrylate.

The layer containing the polymer microspheres composed of the hetero-phase structure particles according to the present invention may optionally include a dispersant, a thickener, an antifoaming agent, a coloring agent, a preservative, a pH adjuster, and the like, if necessary, in addition to the binder. You may mix.

As a method for applying the polymer microspheres comprising the hetero-phase structure particles to the base paper in the present invention, a blade coater,
Any of a roll coater, a brush coater, a curtain coater, a bar coater, a gravure coater, and a size press can be applied.

After providing the layer containing the polymer microspheres comprising the hetero-phase structured particles according to the present invention, the layer may be treated with a super calender, a gloss calender or the like in order to impart surface smoothness.

The coating amount of the polymer microspheres composed in bicomponent particles present invention is preferably ^{0.5~50g / m 2, 1~20g / m} 2
Is more preferred. The required amount of coating may be provided at one time, or the required amount may be obtained by two or more coatings.

The base paper in the present invention is a pulp paper made from natural pulp, synthetic pulp, or a mixture thereof, synthetic paper made from synthetic resin such as polyolefin, polyester, or polyethylene terephthalate film, vinyl chloride film, polyethylene film. And the like. Among these, natural pulp paper containing wood pulp as a main component such as softwood pulp, hardwood pulp, and softwood mixed pulp is advantageously used. As natural pulp paper, lower quality paper, art paper, coated paper, glossy paper,
Examples include impregnated paper and paperboard.

The thickness of the base paper in the present invention is not particularly limited, but is preferably 20 to 300 μm in consideration of the feeling of touch and the like, and is preferably 30 to 2 μm.
50 μm is more preferred.

The resin in the present invention is not particularly limited as long as it has a film forming ability, but is preferably a resin that can be extrusion-coated. For example, polyolefin resin, polyethylene terephthalate resin, ethylene-vinyl acetate copolymer resin, and the like. Examples of the polyolefin resin include homopolymers such as low-density polyethylene, high-density polyethylene, polypropylene, polybutene, and polypentene; copolymers composed of two or more olefins such as ethylene-polypropylene copolymer; and copolymers of ethylene and α-olefin. It is a linear low-density polyethylene which is a coalescence and a mixture thereof. Those having various densities and melt indexes can be used alone or in combination. Particularly, in the present invention, it is most preferable to use low-density polyethylene, high-density polyethylene, medium-density polyethylene, polypropylene, ethylene-polypropylene copolymer, or the like alone or as a mixture of two or more resins.

A white pigment may be added to the resin in the present invention in order to improve the whiteness of the thermal transfer recording image-receiving sheet.
As the white pigment, titanium oxide, zinc oxide, talc, calcium carbonate and the like can be used. Further, in the resin of the present invention, resin amides such as stearamide, arachidic amide, zinc stearate, calcium stearate, aluminum stearate, magnesium stearate, zinc palmitate, zinc myristate, calcium palmitate, etc. Resin acid metal salts, hindered phenols, hindered amines, phosphorus-based, sulfur-based and other antioxidants, blue pigments and dyes such as cobalt blue, ultramarine, celian blue and phthalocyanine blue, cobalt violet, fast violet, manganese violet, etc. Various additives such as magenta pigments and dyes, fluorescent brighteners and ultraviolet absorbers may be added in appropriate combination.

The thickness of the resin layer cover in the present invention is preferably 3 to 50 μm, more preferably 5 to 30 μm.

The present invention is intended to impart the base paper with curl prevention, paper feed suitability, antistatic property and the like on the side (front side) opposite to the side on which the sublimable dye receiving layer is provided (front side) of the base paper. May be provided. The resin is not particularly limited, but the same resin as the resin on the front side is preferable. The application amount of the resin layer provided on the back side can be appropriately set within a range in which the resin layer on the front side can be balanced.

As the synthetic resin used in the sublimable dye-receiving layer in the present invention, polyester resin, polyacrylate resin, polycarbonate resin, polyvinyl acetate resin,
Resins having an ester bond such as styrene acrylate resin and vinyl toluene acrylate resin, resins having a urethane bond such as polyurethane resin, resins having an amide bond such as polyamide resin, resins having an urea bond such as urea resin, and other polycaprolacts Examples thereof include a tan resin, a styrene resin, a polyvinyl chloride resin, a vinyl chloride-vinyl acetate copolymer resin, and a polyacrylonitrile resin.
In addition to these resins, mixtures or copolymers thereof can also be used.

In the sublimable dye-receiving layer in the present invention, a releasing agent, a pigment and the like may be added in addition to the synthetic resin. Examples of the release agent include solid waxes such as polyethylene wax, amide wax, and Teflon powder, fluorine-based and phosphate-based surfactants, and silicone oils. Among these release agents, silicone oil is most preferred. As the silicone oil, an oily substance can be used, but a curable type is preferred. Examples of the curable silicone oil include a reaction curable type, a photocurable type, and a catalyst curable type, and a reaction curable type silicone oil is particularly preferable. Examples of the reaction-curable silicone oil include an amino-modified silicone oil and an epoxy-modified silicone oil. The amount of the reactive silicone oil added is preferably 0.1 to 20% by weight in the sublimable dye receiving layer. As the pigment, extenders such as silica, calcium carbonate, titanium oxide, and zinc oxide are preferable.

The thickness of the sublimable dye-receiving layer is preferably from 0.5 to 20 μm, more preferably from 1 to 10 μm.

EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but the contents of the present invention are not limited to the examples.

Example A layer containing polymer microspheres as shown in Table 1 was applied to one surface of high-quality paper (basis weight 150 g / m ² ) by a blade coater to a dry weight of 10 g / m ² and dried. Next, the low-density polyethylene containing 10% of anatase type titanium oxide (the density of polyethylene before addition of titanium oxide is 0.92 g / cm ³ , MI = 5) and the high-density polyethylene (titanium oxide) Density of polyethylene before addition 0.96 g / cm ³ , M
A resin composition consisting of 7: 3 of I = 5) was heated at a resin temperature of 330 ° C. for 20 minutes.
Melt extrusion coated to a thickness of μm. Next, a resin composition consisting of 1: 1 low-density polyethylene and high-density polyethylene similar to the polyethylene coated on the front surface was applied on the surface (rear surface) opposite to the surface provided with the coating layer at a resin temperature of 330 ° C. for 20 minutes.
Melt extrusion coated to a thickness of μm. Finally, after performing a corona treatment on the surface, a sublimable dye receiving layer having the following composition is applied using a wire bar and dried, and a receiving layer having a solid content applied amount of 5 g / m ² is provided, and an image receiving layer for thermal transfer recording is provided. I got a sheet.

Sublimation dye-receiving layer forming composition Polyester resin (Vylon 200: Toyobo) 10 parts by weight Amino-modified silicone (KF-393: Shin-Etsu Chemical) 0.5 part by weight Epoxy-modified silicone (X-22-343: Shin-Etsu Chemical) 0.5 parts by weight Solvent (toluene / methyl ethyl ketone = 1/1) 89 parts by weight Next, an ink composition for forming a heat-sensitive sublimation transfer layer having the following composition was prepared, and solidified on a 6 μm-thick polyethylene terephthalate film having a heat-treated rear surface. 1 g / m
Coated at ² to obtain a thermal transfer sheet and dried.

Disperse dye (KST-B-714: Nippon Kayaku) 4 parts by weight Polyvinyl butyral resin (BX-1: Sekisui Chemical) 4 parts by weight Solvent (toluene / methyl ethyl ketone = 1/1) 92 parts by weight Thermal transfer obtained above 0.3mJ and 2mJ with thermal head by combining sheet and image receiving sheet for thermal transfer recording
, And solid printing was performed.

The evaluation and determination methods in Table 1 are as follows.

* Transfer density Using a reflection densitometer (Macbeth RD519), applied voltage 2
The transfer density of cyan at mJ was measured.

The higher the transfer density, the higher the sensitivity.

* White spots The occurrence of dot-shaped white spots in the printed area in halftone printing at an applied voltage of 0.3 mJ was visually determined.

 ：: No white drop was observed at all.

 Δ: A slight white drop was observed.

 X: A large amount of white spots are observed.

* Curl The degree of curl of the thermal transfer recording image receiving sheet after solid printing at an applied voltage of 2 mJ was visually determined.

 ：: No curl was observed at all.

 Δ: Some curl is observed.

 X: Severe curl is observed.

[Effects of the Invention] As is clear from the results of the examples, all of the thermal transfer recording image-receiving sheets obtained according to the present invention were free of white spots and curls, had a high transfer density, and were able to obtain beautiful images. .

Claims (3)

(57) [Claims] An image-receiving sheet for thermal transfer recording, comprising: a layer containing polymer microspheres composed of hetero-phase structured particles, a resin layer, and a sublimable dye-receiving layer sequentially laminated on at least one surface of a base paper. 2. The method according to claim 1, wherein the hetero-phase structured particles are polyethyl acrylate.
2. The thermal transfer recording image-receiving sheet according to claim 1, comprising a polystyrene copolymer resin, a polybutyl acrylate-polystyrene copolymer resin, or a polymethyl methacrylate-polystyrene copolymer resin. 3. The image receiving sheet for thermal transfer recording according to claim 1, wherein said resin is polyethylene or polypropylene.