JPH05318950A - Dye thermal transfer image receiving sheet - Google Patents

Abstract

PURPOSE:To provide a dye thermal transfer image receiving sheet capable of obtaining a print image having a high density, free from density irregularity and having excellent image quality. CONSTITUTION:A coating layer containing an active energy beam curable resin is formed on the surface of a base material composed of raw paper containing pulp as a main component and having a low density of 0.2-0.5g/cm<3> and cured by the irradiation with active energy beam to form an image receiving layer.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a dye thermal transfer image receiving sheet (hereinafter referred to as a receiving sheet).
More specifically, the present invention provides a dye thermal transfer image-receiving sheet for receiving an image-forming dye such as a sublimable dye that has been thermally transferred and printing with high sensitivity in a thermal (thermal recording) printer, particularly a dye thermal transfer printer ( Hereinafter, it will be simply referred to as a receiving sheet).

[0002]

2. Description of the Related Art Recently, a thermal printer, especially a dye thermal transfer printer capable of printing a clear full-color image has been receiving attention. A dye thermal transfer printer overlays a sublimation dye ink sheet with a receptive layer containing a dye-dyeing resin of a receptive sheet, and receives heat from a thermal head or the like at a predetermined concentration of a dye in a required portion of the sublimation dye layer. It is transferred onto a layer to form an image.

In order to form a high-quality printed image on a receiving sheet at a high speed with such a thermal printer, an image receiving layer containing a dye-dyeable resin as a main component is provided on a sheet-like substrate. However, if a paper such as coated paper or art paper is used as the sheet-shaped substrate for the receiving sheet,
There is a drawback that the sensitivity for receiving the image forming dye is low.

Therefore, it is known to use a biaxially stretched film containing a thermoplastic resin such as polyolefin as a main component and containing voids (voids) as a sheet-shaped substrate. A receiving sheet using a biaxially stretched film as a sheet-shaped substrate has advantages such as relatively uniform thickness and flexibility, and further, compared with paper made of cellulose fiber,
Since it has low thermal conductivity, it has an advantage that a printed image with high density can be obtained.

However, when such a biaxially stretched film is used as a sheet-like substrate, there is a problem of uneven density of a printed image due to the void structure existing on the surface. Therefore, in order to improve the density unevenness that occurs on the image side, it has been attempted to use a laminate made by laminating a polyolefin resin on a highly smooth paper used as a photographic printing paper substrate as a sheet substrate. ing. However, when such a laminate is used as a sheet-shaped substrate, unevenness in print density occurs due to the unevenness of the fibers in the paper layer, and thus it has not been sufficiently put to practical use.

[0006]

DISCLOSURE OF THE INVENTION The present invention has the drawbacks of the prior arts, namely, when coated paper, art paper, etc. are used as a sheet-shaped substrate, the sensitivity of the resulting receiving sheet is reduced, and the void-containing biaxial coating is produced. An object of the present invention is to provide a dye thermal transfer image receiving sheet having high print density and excellent image quality, by eliminating density unevenness of a print image generated when a stretched film is used as a sheet-shaped substrate.

[0007]

Means for Solving the Problems The inventors of the present invention have earnestly studied a receiving sheet capable of obtaining a printed image of good image quality without uneven density and high image density, and as a result, have a specific density. By using the base paper as a substrate and providing an image receiving layer whose main component is a resin cured by irradiating the surface with active energy rays (hereinafter, referred to as active energy ray-curable resin), the above-mentioned problems are solved. The inventors have found that it can be solved and completed the present invention.

That is, the dye thermal transfer image-receiving sheet of the present invention contains pulp as a main component, and contains 0.2 to 0.
A base paper having a density of 5 g / cm ³ and an image receiving layer formed on at least one surface of the base paper and containing as a main component a resin cured by irradiation with active energy rays. is there.

[0009]

In the receiving sheet of the present invention, a coating composition containing an acrylic compound as a main component which is cured by irradiation with active energy rays is applied to one surface of the base paper to form a coating layer, and the surface of the coating layer is highly coated. While being pressed against the glossy (highly smooth) molding surface, the coating layer is irradiated with an activation energy ray through the base paper to cure it, and then the image receiving layer made of the cured resin obtained by the above operation is applied onto the coating layer. It is obtained by peeling from the glossy molding surface, whereby a receiving sheet containing an image receiving layer having a smooth cast surface can be produced.

The receiving sheet thus obtained has an excellent heat insulating effect derived from the base paper used as the base material, and further has a uniform and highly smooth image-receiving layer in which the influence of the irregularities of the base paper is eliminated. Therefore, it is possible to obtain a print image having a high print density and no image density unevenness and having an excellent image quality.

The base paper used in the present invention is mainly composed of pulp and has a density of 0.2 to 0.5 g / cm ³ . Such a base paper can be obtained by foaming by heating a base paper prepared by blending expandable particles in a pulp slurry.

The type of pulp used for producing such expandable particle-blended base paper is not particularly limited, but for example, wood pulp obtained by subjecting hardwood or softwood to chemical treatment or mechanical treatment, It is possible to use waste paper pulp, non-wood natural pulp such as hemp and cotton, synthetic pulp made from polyethylene, polypropylene and the like. These pulps may be used alone or in combination of several kinds.

In addition to the above pulps, organic fibers such as acrylic fibers, rayon fibers, phenol fibers, polyamide fibers and polyester fibers, glass fibers and carbon fibers,
Various fibers, such as inorganic fibers such as alumina fibers, may be mixed and mixed. However, from the viewpoint of paper-making properties, 5
It is preferable to mix and use 0% by weight or more of pulp.

The expandable particles used for producing the base paper used in the present invention are heat-expandable microcapsules made of a thermoplastic resin containing a low boiling point organic solvent as an expander.
As the low-boiling point organic solvent which is included in the expandable particles and acts as a swelling agent, isobutane, pentane, petroleum ether, hexane, low-boiling point halogenated hydrocarbons, methylsilane, etc. are used, and as the thermoplastic resin to be the shell, ,
Two or more kinds of copolymers such as vinylidene chloride, acrylonitrile, acrylic acid ester and methacrylic acid ester are used. Examples of such expandable particles include trade names: Matsumoto Microsphere F-30D and F-3.
0GS, F-20D, F-50D, F-80D
(Matsumoto Yushi-Seiyaku Co., Ltd.) and trademark: EXPANCEL W
U, the same DU (made by Expancel) are known,
Any of these can be used in the present invention.

When the polymer forming the shell of such expandable particles is heated at a temperature near its softening point, the shell-forming polymer is softened and expanded by the vapor pressure of the expanding agent contained therein. And the capsule expands. The expandable particles are particles having an average particle size of 10 to 30 μm, and by heating at a temperature of 80 to 200 ° C. for a short time, the volume expands 50 to 100 times to form closed cells. Therefore, the base paper produced by mixing pulp and expandable particles and foaming the mixture has low density and excellent heat insulating properties.

The base paper used in the present invention is 0.2 to 0.
It has a density of 5 g / cm ³ . This density is 0.
When it is less than 2 g / cm ³ , the strength of the obtained base paper is lowered, and when it is more than 0.5 g / cm ³ , the heat insulation of the obtained sheet-shaped substrate becomes insufficient.

In order to obtain a base paper having a density of 0.2 to 0.5 g / cm ^3, the amount of expandable particles added is 10% pulp.
1 to 40 parts by weight, preferably 3 to 20 parts by weight relative to 0 parts by weight
It is preferable to use parts by weight, and the heating temperature for foaming is preferably in the range of 110 to 140 ° C. If the amount of the expandable particles to be blended is less than 1 part by weight, sufficient closed cells cannot be obtained and the density of the base paper becomes excessively high. Further, if it exceeds 40 parts by weight, uniform foaming cannot be obtained and the strength of the obtained base paper decreases. Further, if the heating temperature is lower than 110 ° C., sufficient foaming cannot be obtained, and if it is heated at a high temperature exceeding 140 ° C., the shell film of the microcapsule is melted and independent bubbles cannot be obtained.

In the step of mixing pulp and expandable particles, various retention improvers, paper strength enhancers, sizing agents, fillers, etc. may be appropriately selected and added to the pulp slurry,
Further, a dye, a pH adjuster, a slime control agent, an antifoaming agent and the like may be added as required.

It is also possible to apply starch, polyvinyl alcohol, surface sizing agents, pigments and the like to the surface of the raw paper by using a size press, gate roll, blade coater, air knife coater or the like.

Using the above-mentioned constituents as main raw materials, a base paper is made into paper by an ordinary paper machine. First, a wire sheet in the papermaking process is used to form a wet sheet and then a press part is used to dehydrate it. Next, the dehydrated wet sheet is dried in a dryer part. The temperature of the surface of the dryer or multi-cylinder type Yankee type of this dryer part causes the foamable particles mixed in the base paper to foam at the same time as the drying, and Innumerable closed cells are formed in the base paper, which forms a base paper with low density and excellent heat insulation.

The basis weight of the base paper used in the present invention is 10 to 100.
It is preferably g / m ² , and more preferably 20 to
It is 70 g / m ² . If the grammage is less than 10 g / m ² , the resulting base paper will not have a sufficient heat insulating effect and the strength of the base paper will be insufficient. On the other hand, if it exceeds 100 g / m ² , the load on the dryer of the paper machine becomes heavy and the economy becomes poor.

The receiving sheet of the present invention is manufactured by coating and forming an image receiving layer forming coating material containing an active energy ray-curable resin as a main component on the surface of the above-mentioned base paper by a cast coating method.

Examples of the active energy ray-curable resin used in the present invention include (1) aliphatic, alicyclic, and araliphatic 1 to 6-valent alcohols and (meth) acrylates of polyalkylene glycols (2) (Meth) acrylates obtained by adding an alkylene oxide to an aliphatic, alicyclic, or araliphatic 1 to 6-valent alcohol (3) Poly (meth) acryloylalkyl phosphates (4) Carboxylic acid , Polyols, (meth) acrylic acid reactants (5) isocyanate, polyol, (meth) acrylic acid reactants (6) epoxy compound and (meth) acrylic acid reactants (7) epoxy compound, polyol And (meth) acrylic acid reaction products (8) melamine and (meth) acrylic acid reaction products.

The active energy rays used in the present invention include ionizing radiation such as electron rays, ultraviolet rays and γ rays. Above all, it is preferable to use an electron beam obtained from a curtain beam type electron beam accelerator, which is relatively inexpensive and can obtain a large output, as the active energy ray. In this curtain beam system, the acceleration voltage is preferably 100 to 300 Kv, and the absorbed dose is preferably 0.5 to 10 Mrad. The oxygen concentration in the atmosphere during irradiation is 50
It is preferably 0 ppm or less. To form the image receiving layer from the active energy ray-curable resin on the surface of the base paper,
The method described in Japanese Patent Application No. 3-341050 can be advantageously used.

In the present invention, the thickness of the image receiving layer after curing is preferably 5 to 50 μm. If the thickness is less than 5 μm, the density unevenness due to the irregularities on the surface of the base paper is insufficiently solved, and the gradation reproducibility of the heavy color portion of the print image is deteriorated. Also, its thickness is 50 μm
When it exceeds, the heat insulating effect of the obtained base paper becomes insufficient.

The image receiving layer of the present invention preferably contains a silicone compound which is cured by being irradiated with an electron beam in order to prevent the receiving sheet and the ink sheet from being fused to each other during printing. .. The blending amount is
2 to 100 parts by weight of active energy ray curable resin
Suitably 15 parts by weight. If the blending amount is less than 2 parts by weight, the effect of preventing fusion is insufficient, and if the blending amount exceeds 15 parts by weight, the effect is saturated, which is economically disadvantageous.

The image-receiving layer of the present invention may contain a low molecular weight organic compound such as substituted phenol or terpene for the purpose of preventing oxidation, absorbing ultraviolet rays, sensitizing, etc. A white pigment may be added for the purpose of improving the opacity, and a fluorescent dye or a colored dye may be added for the purpose of adjusting the color tone of the image receiving layer, if necessary.

A layer containing an antistatic agent may be provided on at least one surface of the receiving sheet in order to prevent static electricity from being generated during running of the receiving sheet in the printer and causing troubles in running. As the antistatic agent, a cationic hydrophilic polymer compound is advantageously used.

[0029]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. In addition, "parts" and "%" in the examples all represent "parts by weight" and "% by weight".

Example 1 Hardwood bleached kraft pulp beaten to 450 ml Canadian standard freeness (C.S.F.) and conifer bleached kraft pulp beaten to 470 ml Canadian standard freeness (C.S.F.) In a mixed purp slurry consisting of 20%, expandable particles having an average particle diameter of 10 to 20 μm (Matsumoto Yushi-Seiyaku Co., Ltd., trademark: Matsumoto Microsphere F-30D, maximum foaming temperature 130 ° C.) per 100 parts of absolutely dry pulp 5 Part, dry paper strength enhancer (trade name: Polystron 117, manufactured by Arakawa Chemical Co., Ltd.)
2 parts, cationized starch (Oji National, trademark: CA
TO-15) 1 part, alkyl ketene dimer type sizing agent (manufactured by Arakawa Chemical Co., Ltd., trademark: Size Pine K903) 0.03
Parts, and 0.4 parts of a wet paper strengthening agent (trade name: Kamen 575H, manufactured by Dick Hercules Co., Ltd.) were added with good stirring, and then the pulp concentration was adjusted to 0.03% and the pH thereof was adjusted to 7.3. , The inlet raw material was produced.

The inlet raw material thus obtained is used to make a paper using an inclined net paper machine, and is heated and dried in a Yankee dryer at 130 ° C. to foam the expandable particles, which is then dried in a multi-cylinder dryer and then linear pressure is applied. Machine calendered at 30 kg / cm, basis weight 60 g / m ² , thickness 120 μm, density 0.
A base paper of 5 g / cm ³ was prepared.

Then, a rosin urethane acrylate oligomer (trade name: B, manufactured by Arakawa Chemical Co., Ltd.) is formed on one surface of the base paper.
S102) 100 parts, electron beam curable silicone (manufactured by Daicel UCB, trademark: EBACRYL1360) 1
0 part of the active energy ray-curable resin composition was applied with a coating bar so that the coating amount was 10 g / m ² , and the coating surface of the coating layer was pressed against the cast drum, from the back surface of the base paper. The coating layer was cured by irradiating it with an electron beam at an absorbed dose of 3 Mrad to form an image receiving layer, and a receiving sheet was manufactured.

Example 2 A receiving sheet was prepared in the same manner as in Example 1. However, the amount of the expandable particles added was 10 parts (vs. dry pulp). The obtained base paper had a basis weight of 30 g / m ² , a thickness of 120 μm and a density of 0.25 g / cm ³ .

Comparative Example 1 A receiving sheet was prepared in the same manner as in Example 1. However, the amount of the expandable particles added was 2 parts (versus dry pulp). The obtained base paper had a basis weight of 72 g / m ² , a thickness of 120 μm and a density of 0.6 g / cm ³ .

Comparative Example 2 The same operation as in Example 1 was performed. However, as a base material for the receiving sheet, a base material obtained by applying a resin composition comprising 85 parts of polyethylene and 15 parts of titanium dioxide to a coated paper having a thickness of 100 μm using a laminator so that the coating amount is 20 g / m ^2. It was used.

Performance Test A step pattern of a color bar signal generator (manufactured by Shibazoku, trademark: C13A2) was applied to each of the receiving sheets obtained in Examples 1 and 2 and Comparative Examples 1 and 2 by a thermal transfer printer (Sony. Manufactured by Trademark: UP5000), and the obtained print image was evaluated for print density and density unevenness. The results are shown in Table 1.

The print density and density unevenness were evaluated as follows. 1. Print density: The maximum density of the printed image was measured with a Macbeth densitometer (RD-914, Kollmorgen Corp.). 2. Density unevenness: based on a receiving sheet using a laminated base material of synthetic paper / coated paper / synthetic paper, the density unevenness of the printed image is good, good quality is 3, normal quality is 2, poor Sensory evaluation was carried out in three stages, where

[0038]

[Table 1]

[0039]

The dye thermal transfer image-receiving sheet of the present invention makes it possible to obtain a print image having high print density, no uneven density and excellent image quality, which greatly contributes to the industrial world.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Tsunehisa Shigetani 1-10-6 Shinonome, Koto-ku, Tokyo Oji Paper Co., Ltd. Product Research Laboratory

Claims (1)

[Claims] 1. A pulp containing as a main component, and 0.2.
Dye thermal transfer image having a base paper having a density of 0.5 g / cm ³ and an image receiving layer formed on at least one surface of the base paper and containing as a main component a resin cured by irradiation with active energy rays Receiving sheet.