JPH01271289A - Melting type thermal transfer ink image receiving sheet - Google Patents

Abstract

PURPOSE:To reproduce a clear record image stably, by providing a thermally transferred ink image-receiving layer comprising a pigment and a binder resin on an intermediate layer of a polyolefin resin provided on one side of a paper base, and providing a backing layer on the other side. CONSTITUTION:A surface intermediate layer 3 comprising a polyolefin resin as a main constituent is provided on one side 2 of a base 1 comprising a paper made by using a wood pulp as a main constituent, and a thermally transferred ink image-receiving layer 5 comprising a mixture of a pigment with a binder resin material as a main constituent is provided on the intermediate layer. A backing layer 4 comprising a polyolefin resin as a main constituent is provided on the other side of the base, thereby obtaining a receiving sheet 1 for thermally transferred ink images. The intermediate layer 3 preferably comprises a white pigment such as titanium dioxide dispersed therein. The pigment used in the image-receiving layer 5 is preferably calcined clay, particulate silica or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal transfer ink image receiving sheet. More specifically, the present invention provides an ink image receiving sheet for thermal transfer printers capable of reproducing density gradation images, which sharply receives melted transfer ink images, has good midtone reproducibility, and has excellent transferability. Thermal transfer can clearly accept monochrome or multicolor ink images, can print text and images with high resolution, has minimal curling and dimensional changes, and can be used in full-color printer systems. The present invention relates to an ink image receiving sheet.

[Conventional technology]

Thermal transfer of ink images is the mainstream for small non-impact printers, and is often used not only for document and kanji printers, but also for small color printers, and as a result, images with clear halftone reproduction can be obtained. A system and paper were requested. If paper with high resolution and high color reproducibility and compact equipment are realized, it will be possible to make hard copies of full-color images such as videos and computer graphics, and a wide variety of applications are expected.

BACKGROUND ART In a printer using a melt-type ink image thermal transfer method, an ink sheet is used that is composed of a base material such as a film or thin paper and a heat-melt ink layer. A receiving sheet is superimposed on this ink sheet, and according to an image signal, heat transmitted from a thermal head transfers heat-melting ink onto the receiving sheet only in a necessary portion to form an image. In the case of a color printer, images of different colors such as yellow, magenta, cyan, and black are transferred and overlaid to create the desired color.

In such a thermal transfer method, a so-called density gradation method has been proposed in place of the conventional binary density area gradation method image. This method includes, for example, a method that uses sublimable dye and controls the amount of sublimation by the amount of heating of a thermal head.
Recently, heat-melting density gradation transfer using melt ink has been developed, such as controlling the transfer rate of the melt ink by containing a filler in the ink layer, or controlling the transfer amount by multiple coatings of inks with different melting points. A method has been proposed, and its development is attracting attention.

Even if thermal melt ink transfer printers use the area gradation method, the sharpness of the transferred image depends on the smoothness and other characteristics of the receiving sheet, so it is important to ensure that the same high-quality printing and images are produced on any type of paper. It's not possible. Therefore, various techniques have been published for imparting image-receiving suitability to a receiving sheet that is compatible with each printer. In receiving sheets for thermal transfer printers using area gradation methods, in order to obtain good transferred images, regular high-quality paper with a Beck smoothness of about 10 to 50 seconds is smoothed using a super calender, etc. It is known that when the Bekk smoothness is set to 100 seconds or more, the clarity of the transferred image is improved. Furthermore, in order to improve the transfer characteristics of thermal transfer printers, a proposal was made (Japanese Patent Laid-Open No. 57-182487) to provide a coating layer containing an oil-absorbing pigment as a main component on paper to obtain a transferred image with even shading. ing. In this case, most of the pigments used in coated printing papers are listed as usable, and a certain improvement in thermal transfer receptivity has been obtained.

In the thermal transfer method as described above, a special ink sheet is used, and a predetermined amount of ink is transferred from the ink layer on the ink sheet to the thermal layer pressing it in response to the gradual heating of the rad. It is now possible to print a half-tone full-color image with density gradation on the receiving sheet by transferring the image to the receiving sheet.

[Problem to be solved by the invention]

In the density gradation thermal transfer printing method, it is necessary to control the color density of dozens of dots with high precision and good reproducibility in accordance with the continuously changing transfer density, and high resolution is required. is much stricter than the area gradation method.

It is clear that uncoated high-quality paper, in which cellulose fibers are exposed on the surface, cannot satisfactorily meet such demands. Furthermore, by overprinting multiple colors of single colors such as yellow, cyan, and magenta, a myriad of intermediate colors such as red, blue, and green are synthesized, and the uniformity of hue and density can be reproduced as an image by overlapping each dot. It is difficult to obtain a good smoothness even when using high-quality paper or coated paper with a Bekk smoothness of 100 seconds or more.

However, in printers that control the amount of molten ink transferred in response to heating of the thermal head,
The uniformity of the ink receiving ability of the ink receiving layer of the receiving sheet is
This has a serious impact on image reproducibility, and when conventional coated or uncoated thermal transfer receptor sheets are used, uneven density in solid areas and unstable transfer of halftone dots are observed, resulting in poor intermediate quality. No toned image was obtained.

The object of the present invention is to provide a thermal transfer ink image-receiving sheet for full-color printers that can stably reproduce dotted and solid images made of transfer ink from low temperature to high density, and halftone density evenly. It is to provide.

[Means and effects for solving the problems] The thermal transfer ink image-receiving sheet of the present invention comprises a support made of paper whose main component is wood pulp, and a polyolefin-based paper formed on one surface of the support. a surface-side intermediate layer containing a resin as a main component; a thermal transfer ink image-receiving layer formed on the surface-side intermediate layer and containing a mixture of a pigment and a binder resin material as a main component; and the support. A back layer formed on the opposite side of the body and containing a polyolefin resin as a main component.

The thermal transfer ink image-receiving sheet of the present invention solves the conventional problems by using a pigment-containing front side image-receiving layer that absorbs and adhesively receives thermal transfer ink in combination with a support that has both heat resistance and uniformity. It was very successful.

In the thermal transfer receiving sheet 1 of the form shown in FIG.
Formed and bonded to one side of the support 2 made of paper, and a front side intermediate layer 3 mainly composed of a polyolefin resin, and formed and bonded to the other side of the support 2, and A back layer 4 whose main component is preferably a matte polyolefin resin is formed.

It is preferable that a white pigment is dispersed in the surface-side intermediate layer 3, and a thermal transfer ink image-receiving layer 5 is formed and bonded on the surface of this intermediate layer 3.

There are no particular limitations on the type, shape, size, etc. of the base paper used as the support, but high-quality paper and paperboard are generally preferred. A surface-side intermediate layer consisting mainly of polyolefin resin is laminated on paper, but the flatness of the receiving sheet depends on the formation, surface properties, and flatness of the base paper. Good adhesion and surface properties are required. Polyolefin resins used for the surface-side intermediate layer include polyethylene, polypropylene,
Examples include polybutene, polypentene, copolymers thereof, and mixtures thereof, and a white pigment may be mixed with this polyolefin resin.

The white pigment used in the surface-side intermediate layer is titanium dioxide,
It is known to be used for compounding and kneading into conventional polyolefin resins such as zinc sulfide, zinc oxide, calcium sulfate, calcium sulfite, barium sulfate, clay, fired clay, talc, kaolin, calcium carbonate, silica, calcium silicate, etc. You can freely choose from what is available. The white pigment preferably satisfies requirements such as having high whiteness, being usable in a melt-extrusion laminator, and not impairing the flatness of the resulting resin layer or adhesion to the base paper. Generally, when a white pigment is included, the pigment content in the resin layer is preferably in a range of 20% (weight N) or less. When the white pigment content is 20% or more, the strength of the surface-side intermediate layer made of the white pigment-containing polyolefin resin is insufficient, and film cracking is likely to occur.

The intermediate layer-forming polyolefin resin containing or not containing a white pigment is preferably extruded onto a film using a melt extrusion laminator and laminated onto a support. The surface of the resulting intermediate layer has high flatness and, if it contains white pigment, high whiteness. Such an intermediate layer naturally makes the surface of the receptor layer highly flat and has a high degree of whiteness, thus making it possible to form an image with excellent high definition, high sensitivity, and high gradation.

In the thermal transfer receiving sheet of the present invention, the back layer of the support is also formed by extruding a polyolefin resin, preferably by an extrusion lamination method.

If necessary, for example, when extruding and laminating the resin onto a support, a cooling roll whose surface has been matted in a desired pattern is pressed onto the surface of the resin layer, and the cloaked surface of the cooling roll is embossed onto the surface of the resin layer. The back layer can then be matted. The back layer can prevent the receiving sheet from curling, and also makes printing and writing possible on the back surface by matting the back surface of the receiving sheet.

In the receiving sheet of the present invention, a thermal transfer ink image-receiving layer containing a mixture of a pigment and a binder resin material as a main component is formed on the surface-side intermediate layer.

The pigment used in this image-receiving layer is preferably a pigment with high oil absorption, such as fired clay or finely powdered silica. Various clays such as kaolin, calcium carbonate, titanium dioxide, aluminum hydroxide, satin white, talc, calcium sulfite, and others used in conventionally known coated printing papers can be used alone or in combination of two or more. It can be used as

The amount of pigment contained in the image-receiving layer can be determined as appropriate depending on the intended use, but is generally preferably from 10 to 90% by weight, and more preferably from 50 to 85% by weight.

The binder resin material used in the image-receiving layer is, for example, styrene-butadiene, methyl methacrylate-styrene, etc.
It is preferable to use butadiene-based, vinyl acetate-based, or acrylic-based polymers and copolymer emulsions, each singly or in a mixture of two or more. Additionally, water-soluble polymer adhesives such as polyvinyl alcohol, starch, and casein may be used alone or in combination of two or more, and polymer adhesives soluble in organic solvents such as toluene may also be used. It is also possible to form an image-receiving layer using it as a binder resin material.

Further, an antifoaming agent, a dispersant, a conductive agent, a wetting agent, etc. may be included in the image-receiving layer forming coating material as required during coating and printing. After forming the image-receiving layer, if the surface is smoothed using a super calender, etc.
The uniformity of the transferred image is often improved.

The thickness, stiffness, etc. of the thermal transfer ink image-receiving sheet of the present invention are appropriately selected depending on its use, that is, whether it is used for color printing, computer graphics, graphics, cards, etc. is preferably in the range of 60 to 200.

〔Example〕 The invention will be further illustrated by the following examples.

As a support, 30 g of polyethylene resin containing 10% by weight of titanium dioxide was applied to the surface of 170 g/m high-quality paper.
/rd weight to form a surface-side intermediate layer by melt extrusion lamination, and the surface thereof was subjected to corona discharge treatment.

On the other hand, a polyethylene resin having a weight of 25 g/rrf was melt-extruded and laminated on the back side of the support, and the surface thereof was matted to produce an intermediate sheet having a weight of 225 g/rd.

Paint-1 having the following composition was prepared.

Sodium polyacrylate (dispersant) 2 parts Add 30 g of paint-1 onto the corona discharge-treated surface intermediate layer.
rd, and the surface was smoothed by supercalender treatment to obtain a receiving sheet. The Bekk smoothness (Oken method) of the surface of the image-receiving layer was 20,000 seconds, and the smoothness of the back surface was 250 seconds.

The obtained image-receiving sheet was subjected to the following printing process and its performance was evaluated.

■Using ink sheets for each of the three colors of yellow, magenta, and cyan, on which a wax-dye ink layer containing 50 parts of carbon blank as a filler was provided on a 6-layer polyester film as a base material. Then, heat it step by step with the thermal head of a commercially available thermal transfer printer.
The image was thermally transferred to a receiving sheet to print halftone single color and color overlapping images of each color. The image on this receiving sheet was visually evaluated for image clarity, dot uniformity, pig area uniformity, and curling due to heat.

The evaluation results are shown in Table 1 on a 5-grade scale. In the five-level evaluation, 5 indicates excellent performance, 4 indicates good performance, 3 indicates normal performance, 2 indicates poor performance, and ■ indicates extremely poor performance.

Backyard ■1 A 64 g/m high-quality paper was used as a support, and polyethylene resin was laminated on both sides of the paper in an amount of 15 g/d. Apply 2 coats of the following paint-2 on the surface side intermediate layer.
An image receiving layer was formed by coating at a rate of 0 g/rd, and the surface was smoothed by supercalender treatment in the same manner as in Example 1 to obtain a receiving sheet.

The Bekk smoothness (Ouken method) of the image-receiving layer surface of the produced sheet was 18,000 seconds, and the smoothness of the back surface was 250 seconds.

Table 1 shows the printing suitability evaluation of this receiving sheet.

The same high-quality paper as described in Example 2 was used as the support for comparison without polyethylene lamination, and paint-1
was coated at a rate of 35 g/m, and the surface was smoothed by supercalender treatment to obtain a comparative receiving sheet.

The Bekk smoothness (Ouken method) of the image-receiving layer surface of the comparative receiving sheet obtained was 8500 seconds, and the smoothness of the back surface was 400 seconds.
It was seconds.

Table 1 shows the evaluation of the print characteristics of this comparative sheet.

Comparison spot 1 Multi-layered synthetic paper Yubo FP containing inorganic pigment as a support
G 110 (thickness 110 pm, egg oil synthetic paper) was used. Paint-2 was coated on one side of this support at a rate of 20 glrd, and the surface was smoothed by supercalendering to obtain a comparative receiving sheet.

The Bekk smoothness (Oken method) of the image-receiving layer surface of the obtained comparison receiving sheet was 15,000 seconds, and the smoothness of the back surface was 40 seconds.
It was 0 seconds.

Table 1 shows the evaluation of the print characteristics of this comparative sheet.

Margin table below 1 [Effects of the invention] The ink image receiving sheet of the present invention has excellent image gradation, low density uniformity, and high density uniformity, has high color density, and is heat resistant after printing. It has less curling and has excellent image brightness and natural feel, eliminating the drawbacks of conventional methods and making high-resolution melt transfer printing possible.

[Brief explanation of the drawing]

FIG. 1 is an explanatory cross-sectional view of one embodiment of the thermal transfer ink image-receiving sheet of the present invention. 1... Receiving sheet, 2... Support, 3...
- Front side intermediate layer, 4... Back layer, 5... Image receiving layer.

Claims (1)

[Scope of Claims] 1. A support made of paper containing wood pulp as a main component; a surface-side intermediate layer formed on one surface of the support and containing a polyolefin resin as a main component; a thermal transfer ink image-receiving layer formed on the surface-side intermediate layer and containing a mixture of a pigment and a binder resin material as a main component; and a thermal transfer ink image-receiving layer formed on the opposite side of the support and containing a polyolefin resin. A thermal transfer ink image-receiving sheet comprising: a back layer containing as a main component;