JP3089824B2 - Dye thermal transfer image receiving sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dye thermal transfer image receiving sheet (hereinafter, "receiving sheet").
More specifically, the present invention relates to a thermal dye transfer image receiving sheet which receives a thermally transferred image forming dye such as a sublimable dye and prints it with high sensitivity in a thermal (thermal recording) printer, particularly a dye thermal transfer printer. Hereinafter, simply referred to as a receiving sheet).

[0002]

2. Description of the Related Art Recently, a thermal printer, particularly a dye thermal transfer printer capable of printing a clear full-color image, has attracted attention. The dye thermal transfer printer overlaps a sublimation dye ink sheet with a receptor layer containing a dye-dyeable resin of a receptor sheet, and receives a predetermined concentration of dye at a required portion of the sublimation dye layer by heat supplied from a thermal head or the like. The image is transferred onto the layer to form an image.

In order to form a high-quality printed image on a receiving sheet at a high speed by such a thermal printer, an image receiving layer mainly composed of a dye-dyeable resin is provided on a sheet-like substrate. However, as a sheet-like base material for the receiving sheet, when using paper such as coated paper, art paper,
There is a disadvantage that the sensitivity for receiving the dye for image formation is low.

[0004] 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-like substrate. The receiving sheet using the biaxially stretched film as the sheet-shaped substrate has advantages such as relatively uniform thickness and flexibility, and further, as compared with paper made of cellulose fiber, etc.
Due to the low thermal conductivity, there is an advantage that a print with high density can be obtained.

[0005] However, when such a biaxially stretched film is used as a sheet-like substrate, there is a problem of unevenness in density of a printed image due to a void structure existing on the surface. Therefore, in order to improve the density unevenness occurring on the image surface, it has been attempted to use a laminate made by laminating a polyolefin resin on a highly smooth paper used for a photographic printing paper base as a sheet base. ing. However, when such a laminate is used as a sheet-like base material, print density unevenness occurs due to unevenness of fibers in a paper layer, and thus has not been put to practical use.

[0006]

SUMMARY OF THE INVENTION The present invention has the disadvantages of the prior art, namely, when coated paper, art paper, etc. are used as a sheet-like base material, the resulting receptor sheet suffers from reduced sensitivity and void-containing biaxial fibers. An object of the present invention is to provide a dye heat transfer image receiving sheet which has high print density and excellent image quality by eliminating unevenness in density of a printed image generated when a stretched film is used as a sheet-like substrate.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies on a receiving sheet capable of obtaining a printed image of high image density without high density unevenness and having a high image density. By using an original paper as a base material and providing an image-receiving layer mainly composed of a resin cured by irradiating active energy rays on the surface thereof (hereinafter referred to as an active energy ray-curable resin), the above-mentioned problem is solved. The inventors have found that the present invention can be solved and completed the present invention.

That is, the dye thermal transfer image receiving sheet of the present invention is obtained by forming a paper from a pulp slurry containing pulp as a main component and further containing heat expandable particles, and expanding the expandable particles by heating; 0.2 ~
A base paper having a density of 0.5 g / cm ³ and an image receiving layer formed on at least one surface thereof and mainly containing a resin cured by irradiation with active energy rays. Things.

[0009]

The receiving sheet of the present invention forms a coating layer by applying, for example, a coating composition mainly composed of an acrylic compound which is cured by irradiation with active energy rays to one surface of the base paper, and forms a coating layer on the base paper. While being pressed against a glossy (highly smooth) molding surface, the coating layer is irradiated with activation energy rays through the base paper to cure it, and then the image receiving layer made of the cured resin obtained by the above operation is placed on the coating layer. It is obtained by peeling off from the gloss molding surface, whereby a receiving sheet including an image receiving layer having a smooth cast surface can be produced.

[0010] 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 unevenness of the base paper is eliminated. It is possible to obtain a print image of excellent image quality with high print density and no image density unevenness.

The base paper used in the present invention contains pulp as a main component and has a density of 0.2 to 0.5 g / cm ³ , and such base paper is used in pulp slurry. It is obtained by blending heat expandable particles to form a paper, and then expanding the expandable particles by heating.

The type of pulp used for the production of such base paper containing expandable particles is not particularly limited. For example, wood pulp obtained by subjecting hardwood or softwood to chemical or mechanical treatment, Waste paper pulp, non-wood natural pulp such as hemp and cotton, synthetic pulp using polyethylene or polypropylene as a raw material, and the like can be used. These pulp may be used alone or in combination of several kinds.

Further, in addition to the above pulp, organic fibers such as acrylic fiber, rayon fiber, phenol fiber, polyamide fiber, polyester fiber, glass fiber and carbon fiber,
Various fibers such as inorganic fibers such as alumina fibers may be mixed. However, from the viewpoint of papermaking properties, 5
It is preferable to mix 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 organic solvent as an expanding agent.
Isobutane, pentane, petroleum ether, hexane, low-boiling halogenated hydrocarbons, methylsilane, etc. are used as low-boiling organic solvents that are included in the expandable particles and act as swelling agents. ,
Two or more copolymers such as vinylidene chloride, acrylonitrile, acrylates, and methacrylates are used. As such expandable particles, for example, trademarks: Matsumoto Microsphere F-30D and F-3
0GS, F-20D, F-50D, F-80D
(Matsumoto Yushi Seiyaku Co., Ltd.) and trademark: Expancel W
U and the same DU (manufactured by Expancel) are known,
All 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 contained expanding agent. The capsule expands. The expandable particles are particles having an average particle diameter of 10 to 30 µm, and expand by 50 to 100 times to form closed cells by short-time heating at a temperature of 80 to 200 ° C. Therefore, a base paper produced by mixing pulp and expandable particles and expanding the mixture has low density and excellent heat insulating properties.

The base paper used in the present invention is 0.2 to 0.1.
It has a density of 5 g / cm ³ . This density is 0.
If it is less than 2 g / cm ³ , the strength of the obtained base paper will decrease, and if it exceeds 0.5 g / cm ³ , the heat insulating properties of the obtained sheet-like substrate will be insufficient.

In order to obtain a base paper having a density of 0.2 to 0.5 g / cm ³ , the blending amount of the expandable particles is adjusted to 10
1 to 40 parts by weight, preferably 3 to 20 parts by weight with respect to 0 parts by weight
The heating temperature for foaming is preferably in the range of 110 to 140 ° C. If the amount of the expandable particles is less than 1 part by weight, sufficient closed cells cannot be obtained and the density of the base paper becomes excessively high. On the other hand, if it exceeds 40 parts by weight, uniform foaming cannot be obtained, and the strength of the obtained base paper decreases. On the other hand, if the heating temperature is lower than 110 ° C., sufficient foaming cannot be obtained, and if the heating temperature is higher than 140 ° C., the shell film of the microcapsule is melted and closed cells cannot be obtained.

In the step of mixing the pulp and the expandable particles, various retention improvers, paper strength enhancers, sizing agents, fillers and the like 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 necessary.

It is also possible to apply starch, polyvinyl alcohol, a surface sizing agent, a pigment, etc. to the base paper surface by a size press, a gate roll, a blade coater, an air knife coater or the like.

Using the above-mentioned constituents as a main raw material, a base paper is formed by an ordinary paper machine. First, a wet sheet is formed in a wire part in a paper making process, and then dehydrated in a press part. Next, the dewatered wet sheet is dried by a dryer part. According to the temperature of the surface of the multi-cylinder or Yankee type dryer of the dryer part, the foamable particles mixed into the base paper are foamed simultaneously with the drying, and the base paper is dried. In addition, numerous closed cells are formed, thereby forming a base paper having low density and excellent heat insulation.

The basis weight of the base paper used in the present invention is 10 to 100.
g / m ² , more preferably 20 to
70 g / m ² . When the basis weight is less than 10 g / m ² , the obtained base paper cannot have a sufficient heat insulating effect and the base paper strength becomes insufficient. On the other hand, if it exceeds 100 g / m ² , the load on the dryer of the paper machine increases, and the economic efficiency deteriorates.

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

The active energy ray-curable resins used in the present invention include: (1) aliphatic, alicyclic and araliphatic mono- to hexavalent alcohols and (meth) acrylates of polyalkylene glycols (2) (Meth) acrylates obtained by adding an alkylene oxide to aliphatic, alicyclic and araliphatic mono- to hexavalent alcohols (3) Poly (meth) acryloylalkyl phosphates (4) Carboxylic acid , Polyol, reactant of (meth) acrylic acid (5) isocyanate, polyol, reactant of (meth) acrylic acid (6) reactant of epoxy compound and (meth) acrylic acid (7) epoxy compound, polyol And (meth) acrylic acid reactants (8) Melamine and (meth) acrylic acid reactants.

The active energy rays used in the present invention include ionizing radiations such as electron beams, ultraviolet rays, and γ rays. Among them, it is preferable to use an electron beam obtained from a curtain beam type electron beam accelerator, which is relatively inexpensive and provides a large output, as an active energy beam. 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 an image receiving layer on the base paper surface from an active energy ray-curable resin,
The method described in Japanese Patent Application No. 3-341050 can be advantageously used.

In the present invention, the cured thickness of the image receiving layer is preferably 5 to 50 μm. If the thickness is less than 5 μm, density unevenness caused by unevenness on the surface of the base paper will not be sufficiently eliminated, and further, the tone reproducibility of the superimposed color portion of the printed image will be deteriorated. The thickness is 50 μm
When the ratio 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 irradiation with an electron beam in order to prevent the receiving sheet and the ink sheet from fusing during printing. . The amount is
2 to 100 parts by weight of the active energy ray-curable resin
Suitably it is 15 parts by weight. If the amount is less than 2 parts by weight, the effect of preventing fusion is insufficient, and if the amount exceeds 15 parts by weight, the effect is saturated, so that it is economically disadvantageous.

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

Further, 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 running trouble. As the antistatic agent, a cationic hydrophilic high molecular compound is advantageously used.

[0029]

The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. In the examples, "parts" and "%" all indicate "parts by weight" and "% by weight".

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

The obtained inlet raw material is used to make paper using a slant net paper machine, and is dried by heating with a Yankee dryer at 130 ° C. to expand the expandable particles, and then dried using a multi-cylinder dryer. Machine calendering at 30 kg / cm, basis weight 60 g / m ² , thickness 120 μm, density 0.
A 5 g / cm ³ base paper was prepared.

Next, a rosin urethane acrylate oligomer (Arakawa Chemical, trade name: B
S102) 100 parts, electron beam-curable silicone (manufactured by Daicel UCB, trademark: EBACRYL1360) 1
The active energy ray-curable resin composition consisting of 0 parts is applied by a coating bar so that the coating amount becomes 10 g / m ² , and the coated surface of the coated layer is pressed against a cast drum, and from the back of the base paper. The coating layer was cured by irradiating an electron beam so as to have an absorption dose of 3 Mrad to form an image receiving layer, thereby producing a receiving sheet.

Example 2 A receiving sheet was produced in the same manner as in Example 1. However, the added amount of the expandable particles was 10 parts (vs. absolutely 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 produced in the same manner as in Example 1. However, the added amount of the expandable particles was 2 parts (vs. absolutely 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 a 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 as to have an application amount of 20 g / m ^2. It was used.

Performance Test A step pattern of a color bar signal generator (manufactured by Shivazoku Co., Ltd., trade name: C13A2) was provided on each of the receiving sheets obtained in Examples 1 and 2 and Comparative Examples 1 and 2 with a thermal transfer printer (Sony). (Trade name: UP5000), and the obtained print image was evaluated for print density and density unevenness. Table 1 shows the results.

The print density and the density unevenness were evaluated as follows. 1. Print density: The maximum density of a printed image was measured with a Macbeth densitometer (RD-914, manufactured by Kollmorgen Corp.). 2. Density unevenness: The density unevenness of the printed image was 3 for good, 2 for general quality, and inferior for the print image, based on the receiving sheet using synthetic paper / coated paper / synthetic paper bonding base material. The sensory evaluation was carried out in three steps, where

[0038]

[Table 1]

[0039]

According to the dye thermal transfer image receiving sheet of the present invention, it is possible to obtain a print image having a high print density, no density unevenness and excellent image quality, which greatly contributes to the industry.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tsunehisa Shigetani 1-10-6 Shinonome, Koto-ku, Tokyo Oji Paper Co., Ltd. Product Research Institute (56) References JP-A-3-10890 (JP, A) JP-A-2-206590 (JP, A) JP-A-4-45902 (JP, A) JP-A-5-286260 (JP, A) JP-A-6-106866 (JP, A) JP-A-4-128917 ( JP, A) JP-A-5-318951 (JP, A) JP-A-5-185759 (JP, A) JP-A-61-6649 (JP, A) JP-A-62-44495 (JP, A) Sho 62-204988 (JP, A) JP-A-5-318949 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41M 5/38-5/40

Claims (1)

(57) [Claims] 1. A paper is made from a pulp slurry containing pulp as a main component and further containing heat-expandable particles, obtained by expanding the expandable particles by heating, and 0.2 to 0.5 g / cm. A dye thermal transfer image receiving sheet comprising: a base paper having a density of 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.