JP2588574B2 - Receiving paper for thermal transfer printer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a receiving paper for a thermal transfer printer. More specifically, the present invention is useful for a thermal transfer printer including a sublimation dye transfer, and particularly in a thermal transfer printer using a hot-melt dye ink ribbon, a hot-melt transfer method for sharply transferring the melted ink. The present invention relates to a receiving paper suitable for a full-color printer and capable of printing characters and images with high resolution.

(Prior art)

Recently, demand for color printing and color printers has been increased, and particularly, hot-melt type transfer type printers using thermal heads and dye sublimation fragment transfer type printers have been widely noted for their vivid color images.

Among these, printers of the fusion transfer type are films,
An ink sheet comprising a base material such as thin paper and a hot-melt ink layer is used. A receiving paper such as a normal high-quality paper is superimposed on the ink sheet, and only a necessary portion of the hot-melt ink is transferred to the receiving paper by heat from a thermal head according to an image signal to form an image. In the case of a color printer, images of different colors such as yellow, magenta, cyan, and black can be transferred and superimposed to obtain a color image.

However, such a hot-melt transfer printer can form the same high-level printed image on any type of paper because the sharpness of the transferred image depends on the requirements such as the smoothness of the receiving paper. is not. Therefore, various techniques have been proposed for imparting image receiving suitability corresponding to each printer to receiving paper.

In such a thermal transfer printer, it is possible to reproduce a halftone using an area gradation method and print a full-color image. In this receiving paper for a thermal transfer printer of the image gradation method, in order to obtain a good transfer image, ordinary fine paper having a Beck smoothness of about 10 to 50 is smoothed using a super calender or the like, and the Beck smoothing is performed. It is known that when the degree is set to 100 seconds or more, the sharpness of a transfer image of the obtained receiving paper is improved.

However, the demand for resolution has further advanced,
The demand for high resolution of 16 dots / mm or more is beginning to be demanded for thermal transfer printers, and a method for controlling the size of transferred dots with an accuracy of 10 μm or less has been announced. Therefore, in this application, the limit of the uncoated paper having the cellulose fiber exposed on the surface is obvious. Furthermore, it is possible to obtain a color obtained by multicolor printing of a single color of yellow, cyan, and magenta, that is, red, blue, and a hue of green and a uniform density with good reproducibility as an image formed by overlapping dots.
For example, it is difficult even for high quality paper or coated paper having a Beck smoothness of 100 seconds or more. For example, in order to improve the transfer characteristics of a thermal transfer printer, there has been proposed a receiving paper (Japanese Patent Laid-Open No. 57-182487) which obtains a transferred image without unevenness in density by providing an oil-absorbing pigment layer on a paper substrate. This publication lists most of the pigments used in coated paper for printing, and has obtained a certain improvement in thermal transfer receptivity. Further, it is proposed to obtain a transferred image without unevenness in density by providing a coating layer comprising a pigment containing calcium carbonate as a main component and a latex of a copolymer containing an unsaturated carboxylic acid as a component of a monomer on a paper substrate. (JP-A-57-182487).

However, in high-definition printers, such as the so-called density gradation method, which controls the transfer amount of the molten ink from the thermal head, the uniformity of the ink receiving capacity of the receiving layer is important for image reproducibility. Even when using conventional pigment-coated paper and uncoated super-processed high-quality paper, uneven density in solid areas and unstable transfer of dots were observed.
It has been difficult to reproduce a good halftone and obtain a full-color image having high resolution.

[Problems to be solved by the invention]

In view of the above-mentioned current situation, the present invention has no unevenness in density of dots formed of transfer ink, and solid portions, and has a stable halftone, and is continuously reproduced from low density to high density. It is an object of the present invention to provide a thermal transfer receiving paper which can obtain a clear recorded image and has a high resolution and is used for a full-color printer. By using such receiving paper, a high-quality halftone image reproducibility that has never been seen before can be obtained, and by realizing such high-resolution, color-reproducing paper, a color video screen can be obtained. Hard copies of full-color images can be created with a compact device, and various applications can be made.

[Means for solving the problem]

The receiving paper for a thermal transfer printer of the present invention comprises a support made of neutral paper, and an image receiving layer formed on at least one surface thereof and containing a pigment and a binder resin material. Wherein the pigment comprises spindle-shaped particles of light calcium carbonate of calcite-type crystal system, and the binder resin material comprises an acrylate copolymer as a main component thereof, and The weight of the layer is 3 to 30 g / m ² . On the receiving paper for a thermal transfer printer as described above, the reliability of one halftone dot, the density reproducibility, and the hue of solid color overlap are determined by the image forming method that reproduces the halftone image by the density gradation or area gradation method. And the reproducibility of the concentration can be improved,
The reproducibility of the hue and density of a full-color recorded image can be realized, and the problems of the conventional receiving paper can be improved.

The water extraction pH of the neutral paper support used in the present invention is 6-9. The water extraction pH indicates the hydrogen ion concentration of an extract obtained by extracting a test piece with water as specified in JIS-P-8133.

The neutral paper support in the present invention may be sized by any size method as long as the resulting water extraction pH is close to neutral. Specific sizing means include alkyl ketene dimers, cellulose reactive sizing agents such as substituted cyclic dicarboxylic anhydrides, epoxidized higher fatty acid amides, cationic styrene-maleic anhydride copolymers, and cationic cationic resins such as cationized petroleum resins. Self-fixing type sizing agent and sizing by attaching to the surface of paper, such as styrene-acrylic acid copolymer, styrene-maleic acid copolymer, α-olefin-maleic anhydride copolymer, petroleum resin, etc. A so-called external sizing agent or the like which expresses the neutral paper support of the present invention,
It is preferable to use an alkyl ketene dimer to obtain These sizing agents may be used alone or as a mixture of two or more. The neutral paper support used in the present invention is preferably a water-absorbing material having a basis weight of 64 g / m ² and a Steckigt sizing degree of 5 to 30 seconds. The measurement of the degree of Stekicht size is JIS-P-8
122 methods. When the Stekigt sizing degree is 5 seconds or less, the pinholes of the pigment coating layer may increase and the quality of the image may be impaired. Absorption of the paint during coating is large, and the uniformity of the coated surface may be poor.

The amount of the sizing agent and the fixing agent is based on the basis weight of the paper support,
The sizing agent is used in an amount of about 0.1 to 1.5% by weight based on the weight of the solid pulp, and the fixing agent is used in an amount of about 0.2 to 2.0% by weight based on the weight of the solid pulp.
However, it is important to select the size conditions so that the water extraction pH of the paper support falls within the range described above.

The neutral paper used in the present invention may be filled with light calcium carbonate having calcite-type crystals at a ratio of 10 to 40% by weight.

The receiving paper for a hot-melt transfer printer of the present invention has an image receiving layer formed on at least one surface of a neutral paper support and containing a pigment and a binder resin material. The image-receiving layer has a weight of 3 to 30 g / m ^2, the pigment therein are those containing spindle-shaped particles of precipitated calcium carbonate of calcite type crystalline and crystalline resin material, the It contains an acrylate copolymer as a main component. When the image receiving layer has a weight lower than 3 g / m ^2, it becomes difficult to uniformly coat the surface of the paper support, and therefore, uneven density of a printed image occurs. Further, even if the weight of the image receiving layer is increased beyond 30 g / m ² , the effect is saturated and the strength of the coating film is lowered.

The pigment used in the image receiving layer of the present invention contains light calcium carbonate having a spindle shape and a calcite crystal type as described above, but has a hexagonal column shape and a crystal shape. It may contain calcite-type light calcium carbonate. The pigment used in the present invention may contain 50 to 90% by weight of calcite-type crystalline light calcium carbonate spindle-shaped particles and 10 to 50% by weight of calcined kaolin.

The pigment particles preferably have a particle size of 0.1 μm to 5 μm. The image-receiving layer is made of various types of clay, calcined clay, titanium dioxide, aluminum hydroxide, satin white, talc, calcium silicate, calcium sulfate, magnesium silicate, and synthetic amorphous silica used for general coating. Pigments and organic pigments such as styrene-based plastic pigments, acrylic-based plastic pigments, and urea resins may be blended.

The pigment of the image receiving layer of the present invention preferably contains at least 50% by weight of the calcite-type crystalline light calcium carbonate spindle-shaped particles.

The binder resin material used in the present invention has a Tg of 0 ° C. or less,
At least two or more copolymers selected from alkyl acrylates and alkyl methacrylates are contained as main components. Specific examples of copolymers of alkyl acrylates and alkyl methacrylates, which are usually used as an emulsion polymer dispersed in water, include ethyl acrylate, butyl acrylate, ethylhexyl acrylate, nonyl acrylate, butyri methacrylate, and dodecyl methacrylate. , A copolymer of two or more selected from 2-ethylhexyl methacrylate, nepentyl methacrylate polymer, methyl acrylate, methyl methacrylate, ethyl methacrylate, etc., or a comonomer such as vinyl acetate, acrylic acid, methacrylic acid, etc. May be included. These copolymers may be used alone or as a mixture of two or more polymers. Further, a water-soluble adhesive such as styrene-butadiene resin, starch or polyvinyl alcohol may be used in the binder resin material.

In the receiving paper for a fusion transfer printer of the present invention, the blending ratio of the pigment and the binder resin material in the image receiving layer is
The binder resin material is preferably 5 to 30 parts by weight, more preferably 10 to 20 parts by weight, per 100 parts by weight. In general, if the compounding ratio of the binder resin material is less than 5 parts by weight, the coating strength of the obtained image receiving layer may be insufficient, and if it exceeds 30 parts by weight, poor absorption of the melt-transferred ink may occur. The color reproducibility and resolution of the image may be insufficient.

〔Example〕

Next, the receiving paper for a thermal transfer printer of the present invention will be described with reference to examples. "Parts" used in the examples are parts by weight of solid content.

The cardboard used in the examples was formed as follows.

Base paper making (64 g / m ² ) 0.2% alkyl ketene dimer sizing agent (Dick Hercules, Acopel 360) in wood pulp (LBKP 80%, NBKP 20%) slurry beaten to Canadian Freeness 340CC, and cation Starch (manufactured by National Starch, CATO-F) 2%.
(2) Separately, 0.2% of Acopel 360 (manufactured by Dick Hercules, alkyl ketene dimer) is added to the slurry,
Cationic starch (National Starch, CATO-
F) 2% and light calcium carbonate (Shiraishi Kogyo, P
C) and 20% of the pulp weight. (3) Separately,
1% rosin and 2% sulfuric acid band were added to the slurry. The pH before each papermaking is (1) 7.0 (2) 7.7 (3)
It was 4.5. A paper support having a basis weight of 64 g / m ² was obtained from each of the slurries by a usual papermaking method. The Stekigt sizing degree of each paper support was (1) 25 seconds (2) 10 seconds (3) 30 seconds. The water extraction pH of cardboard (1), (2) and (3) was as follows.

(1) Neutral paper Water extraction pH = 6.7 (2) Calcium carbonate-filled neutral paper Water extraction pH = 6.7 (3) Rosin size acidic paper Water extraction pH = 4.5 Example 1 Coating layer composition Light calcium carbonate (Shiraishi Industrial, PC, calcite-type crystals, spindle-shaped particles) 70 parts Calcined clay (Ansilex U.S.A. Engelhardt) 30 parts Acrylic ester-based copolymer latex (Hoechest Gosei, Movinyl 760) 20 parts Starch oxide ( Made of Prince Corn Starch, Prince Ace A)
5 parts by weight of the above paint on the recording surface of the paper support (1)
Coating was performed at a coating amount of 7 g / m ² , which was dried and smoothed with a super calender. The Beck smoothness (Oken type) of the recording surface of the obtained receiving paper was 600 seconds, and the smoothness of the opposite surface was 30 seconds.

Example 2 A paint identical to that described in Example 1 was applied to a paper support (1).
Was coated at a solid content weight of 20 g / m ² , dried, and smoothed with a super calender. The recording surface of the obtained sheet has a Beck smoothness (Oken type) of 800 seconds,
The smoothness of the opposite side was 40 seconds.

Comparative Example 1 A paint having the same composition as that described in Example 1 was applied to the recording surface of the paper support (3) at a solid content of 7 g / m ² .
The recording surface of the obtained receiving paper has a Beck smoothness (Oken type) of 80
0 second and the smoothness of the opposite side was 40 seconds.

Example 3 Composition of Coating Solution for Forming Image-Receiving Layer Light Calcium Carbonate (Shiraishi Kogyo, PK, Calcite Crystalline, Spindle-shaped Particles) 100 parts Acrylic ester-based copolymer latex (Hoechest Gosei, Movinyl 760) 20 parts Oxidized starch (Oji Corn Chitach, Oji Ace A)
5 parts The above coating material was applied to the recording surface of the paper support (2) at a solid content of 7 g / m ² , dried, and smoothed by a super calender. The recording surface of the obtained receiving paper had a Beck smoothness (Oken type) of 800 seconds, and the smoothness of the opposite surface was 4 seconds.
It was 0 seconds.

Comparative Example 2 A coating material having the same coating layer composition as that described in Example 1 was applied to the recording surface of the paper support (3) at a solid content weight of ² g / m ² . The Beck smoothness (Oken type) of the recording surface of the obtained receiving paper was 150 seconds, and the smoothness of the opposite surface was 40 seconds.

Comparative Example 3 The paper support (2) of Example 3 was used as it was and subjected to the following thermal transfer test.

Comparative Example 4 Light calcium carbonate (PC, calcite-type crystal, spindle-type particles, manufactured by Shiraishi Kogyo Co., Ltd.) described in Example 1 was replaced with light calcium carbonate (Brilliant-15, calcite-type crystal manufactured by Shiraishi Kogyo). , Cubic particles), and the coating material prepared under the same conditions as in Example 1 was applied to the recording surface of the paper support (1) at a solid weight of 20 g / m ² , dried, and dried. Was smoothed with a super calendar. The recording surface of the obtained sheet had a Beck smoothness (Oken type) of 500 seconds, and the opposite surface had a smoothness of 40 seconds.

Comparative Example 5 A styrene-butadiene latex (JSR 0642, manufactured by Nippon Synthetic Rubber Co., Ltd.) was used in place of the acrylate-based copolymer latex for coating layer described in Example 1. Otherwise, the paint obtained in the same manner as in Example 1 was applied to the recording surface of the paper support (1) at a solid weight of 20 g / m ² , dried, and smoothed with a super calender. . The recording surface of the obtained sheet had a Beck smoothness (Oken type) of 600 seconds, and the opposite surface had a smoothness of 40 seconds.

Example of Thermal Transfer Printing The receiving paper for a thermal transfer printer obtained in each of the above Examples and Comparative Examples was coated on a 6 μm-thick polyester base material using a commercially available melt thermal transfer color printer, and a wax-pigment ink was placed on the polyester. From each of the three ink sheets of yellow, magenta, and cyan provided with a layer, thermal transfer was performed on a receiving paper, and a single-color and multi-color image of each color was printed. The image on the receiving paper was visually evaluated for image clarity, dot uniformity, and solid portion uniformity.

The results are shown in Table 1. Particularly excellent evaluation results are indicated as 4, excellent ones, three with slight defects, and ones with remarkable defects.

[Effects of the Invention] As is clear from the results of the above Examples and Comparative Examples, the receiving paper for a thermal transfer printer of the present invention has sharpness of color development, gradation, low density, and high density uniformity. This method solves the drawbacks of the conventional method and makes it possible to perform hard copy with a small-sized full-color thermal transfer printer, which greatly contributes to the industry.

Claims (1)

(57) [Claims] 1. A support comprising neutral paper, and an image receiving layer formed on at least one surface thereof and containing a pigment and a binder resin material, wherein the pigment in the image receiving layer is The binder resin material contains spindle-shaped particles of light calcium carbonate of a site type crystal system, and the binding resin material contains an acrylate copolymer as a main component thereof, and the weight of the image receiving layer is 3 to 30 g. / m ² , receiving paper for a thermal transfer printer.