JPH06227172A - Heat transfer dye accepting sheet - Google Patents

Abstract

PURPOSE:To provide a heat transfer dye accepting sheet having clear printed image by a method wherein favorable printability is realized when the sheet concerned is used on a heat transfer dye printer and uneven density developing under the condition that base material laminated with thermoplastic resin is employed is settled. CONSTITUTION:The sheet concerned has resin covering layer, which is formed on one side of support mainly made of cellulose pulp and having the basis weight of 100g/m<2> and mainly made of thermoplastic resin such as polyethylene mixed with 13% of titanium dioxide by the covering weight of 20g/m<2> by lamination, and accepting layer, which is formed on the resin covering layer and accepts heat transfer image forming dye for dyeing such as polyester resin or the like. In the case, the support of the heat transfer dye accepting sheet concerned is base paper, which (1) is made of cellulose pulp having the freeness of 450cc or more, (2) has the density of 0.7-0.9g/m<3> and (3) has the smoothness of 20-120sec.

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 receiving sheet (hereinafter simply referred to as a receiving sheet).
More specifically, the present invention, in a thermal (thermal recording) printer, particularly a dye thermal transfer printer, dyes and receives an image forming dye such as a sublimable dye that has been thermally transferred to form a clear image without density unevenness. The present invention relates to a receiving sheet that can be used.

[0002]

2. Description of the Related Art In recent years, a thermal transfer type high-quality color hard copy, especially a dye thermal transfer type printer has been rapidly developed. In the dye thermal transfer printer, the sublimable dye layers of three colors (yellow, magenta, and cyan) are heated by continuously controlling the heating energy of the thermal head, and the transfer amount of the dye of each color is changed to change the density. It enables full-color images with gradation.

With such a dye thermal transfer printer,
In order to form high-quality prints on a receiving sheet at high speed, use a biaxially stretched film containing thermoplastic resin such as polyolefin as a main component and having a large number of micropores as a base material of the receiving sheet. It has been known. In a dye thermal transfer receiving sheet (hereinafter referred to as a receiving sheet), an image receiving layer containing a thermoplastic resin as a main component is provided on this base material. The receiving sheet using such a base material has advantages that it has a uniform thickness, is flexible, and has a lower thermal conductivity than paper made of cellulose fiber, and therefore has a uniform and high density print. It has the advantage that

However, such a biaxially stretched film is
When used as the base material of a receiving sheet that requires high image reproducibility, the residual stress during stretching is returned by the heat during printing,
Heat contraction occurs in the stretching direction, resulting in curling or wrinkling of the receiving sheet, which causes troubles such as paper jams in the receiving sheet traveling in the printer.

In order to improve the above-mentioned defects such as curling or wrinkling, a laminated sheet obtained by laminating stretched films on both sides of a core material having a relatively small heat shrinkability or a core material having a large elastic modulus is used as a base material. Known to be used. However, since such a base material is formed by laminating sheets having different heat shrinkage rates, curling is likely to occur due to the difference in the shrinkage rate due to heat or the like. In addition, even if the difference in shrinkage ratio of the stretched films laminated on the front and back is the same, heat is applied only to the front side during printing, so there is a difference in temperature between the front and back sides of the receiving sheet, and therefore shrinkage occurs on the front and back sides. Curling occurs due to the difference in the rate. Further, since the stretched films are laminated on the front and back sides, there is a problem that the cost is significantly increased.

In order to eliminate unevenness in image density without using the above-mentioned stretched film having heat deformability as a substrate, JP-A-2-106397 and JP-A-2-106397 have been used.
No. 307786 has a thickness of 5 on the surface of highly smooth paper.
It has been proposed to use a base material laminated with a polyolefin resin having a coating amount of ˜35 μm and a coating amount of 5 to 25 g / m ² . In these cases, the image quality can be improved to some extent by appropriately laminating, but the uneven density is not sufficiently improved.

[0007]

DISCLOSURE OF THE INVENTION The present invention eliminates uneven density of an image which occurs when a base material provided with a thermoplastic resin coating layer on a base paper is used as a dye thermal transfer receiving sheet, and is inexpensive. An object of the present invention is to provide a dye thermal transfer receiving sheet having excellent image quality and high transferred image density.

[0008]

A dye thermal transfer receiving sheet according to the present invention comprises a support containing cellulose pulp as a main component, and a thermoplastic resin as a main component formed on one surface of the support. A resin coating layer containing the same, and an image receiving layer formed on the resin coating layer and dyeing and receiving a thermal transfer image forming dye, wherein the support is composed mainly of (1) cellulose pulp having a freeness of 450 cc or more. It is characterized in that it is composed of a base paper which is formed as a component, (2) has a density of 0.7 to 0.9 g / cm ³ , and (3) has a smoothness of 20 to 120 seconds. The above problem can be solved by satisfying these conditions.

[0009]

The base paper used as the support of the present invention and containing cellulose pulp as the main component has a freeness of 45.
It is formed from 0 cc or more of cellulose pulp. Various known refiners can be used to adjust the freeness. Alternatively, pulp that has not been beaten by a refiner or the like may be used. The type of pulp used is not particularly limited, but for example, wood pulp such as chemical and mechanical pulp of hardwood and conifer, waste paper pulp, non-wood natural pulp such as hemp and cotton, polyethylene and polypropylene as raw materials. Examples thereof include synthetic pulp and the like, and these may be used in combination. In particular, it is preferable to use a hardwood chemical pulp.

In addition to the above-mentioned cellulose pulp, the base paper forming the support of the present invention includes organic fibers such as acrylic fiber, rayon fiber, phenol fiber, polyamide fiber, polyester fiber, glass fiber, carbon fiber, alumina fiber and the like. Various kinds of fibers such as the inorganic fibers may be mixed and made. From the viewpoint of paper-making property, it is preferable to add 50% by weight or more of cellulose pulp.

In the process of making pulp, various anionic, nonionic, cationic or amphoteric retention aids, paper strength enhancers, sizing agents and fillers can be appropriately selected and used. A paper making additive such as a pH adjusting agent, a slime controlling agent, an antifoaming agent, etc. can also be used according to the application. It is also possible to apply starch, polyvinyl alcohol, a surface sizing agent, a pigment or the like to the surface of the raw paper by using a coating method such as a size press, a gate roll, a blade coater or an air knife coater.

Freeness of 450cc in base paper making
The above pulp is used as a main raw material and formed into a sheet by a normal paper machine. First, it is formed into a sheet by the wire part in the papermaking process, and then dehydrated by the press part. Then, it is dehydrated in a dryer part.

The base paper mainly composed of cellulose pulp of the present invention has a density of 0.7 to 0.9 and a smoothness of 20 to 1.
It should be in the range of 20 seconds. When the density is less than 0.7 and / or the smoothness is less than 20 seconds, the unevenness of the paper surface appears on the surface of the receiving layer, the print image is not transferred to the recesses on the surface of the receiving layer, and the transfer is not transferred to the printed surface. It remains as a section.
If the density is higher than 0.9 and / or the smoothness is higher than 120 seconds, no untransferred portion remains on the printed surface, but density unevenness due to the cellulose fibers occurs.

The resin coating layer in the present invention is preferably formed by extrusion-coatable polyolefin resin. For example, a homopolymer of low density polyethylene, high density polyethylene, polypropylene, polybutene, polypentene, or the like, or a copolymer of two or more olefins such as an ethylene-polypropylene copolymer, or a copolymer of ethylene and an α-olefin. The linear low-density polyethylene which is a polymer, and a mixture of two or more kinds thereof can be used, and those having various densities and melt indexes can be used alone or by mixing them.

A white pigment is preferably added to the resin coating layer of the present invention in order to improve the whiteness of the receiving sheet. Titanium oxide, zinc oxide, talc, calcium carbonate and the like can be used as the white pigment. Further, in the present invention, a resin metal salt such as stearic acid amide or zinc stearate, an antioxidant such as hindered phenol, or a pigment or dye such as cobalt blue or ultramarine may be added to the resin coating layer.

In the present invention, the coating amount of the resin coating layer is 1
It is preferably from 0 to 25 g / m ² . This is 10g /
When it is less than m ^2, uneven density occurs in the image on the obtained receiving sheet, and when it is more than 25 g / m ² , the density of the printed image decreases.

The image-receiving layer resin which can be used in the image-receiving layer of the present invention includes thermoplastic saturated polyester resin, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl propionate copolymer and the like. A vinyl chloride resin is preferable, but other polycarbonate resins, polyvinyl acetals, polyamides, polyacrylic acid esters, active energy ray curable resins and the like may be used.

The image-receiving layer of the present invention may be blended with a low molecular weight organic compound such as a substituted phenol or terpene for the purpose of preventing oxidation, absorbing ultraviolet rays, sensitizing or the like. White pigments commonly used to improve the whiteness and opacity of paints,
Fluorescent dyes for adjusting the color tone of the image receiving layer, as well as blue or violet dyes can be added as required.

It is convenient to mix the above-mentioned additives such as a white pigment, an ultraviolet absorber and a cross-linking agent with the image-receiving layer resin which constitutes the main component of the image-receiving layer and to apply the mixture. May be coated on or under the image receiving layer.

Further, a releasing agent may be used in the image receiving layer in order to enhance heat resistant fusion between the ink sheet and the image receiving layer due to heat when printing. As such a release agent, waxes such as paraffin and polyethylene wax, metal soap, silicone oil, silicone resin,
It is possible to add a fluorinated surfactant, a fluorinated resin, and the like, and the added amount is preferably 15% by weight or less of the image receiving weight.

An intermediate layer may be provided between the resin coating layer and the image receiving layer in order to improve the adhesion between them. Various hydrophilic resins and / or hydrophobic resins can be used for forming the intermediate layer. For example, vinyl polymers such as polyvinyl alcohol and polyvinylpyrrolidone and their derivatives, polyacrylamide, polydimethylacrylamide, polyacrylic acid or Salts thereof, polymers containing acrylic groups such as polyacrylic acid esters, polymers containing methacrylic groups such as polymethacrylic acid, polymethacrylic acid esters, starch, sodium alginate, gum arabic,
Natural polymers or derivatives such as casein and carboxymethyl cellulose can be appropriately used.

An antistatic agent may be applied to at least one surface of the receiving sheet in order to prevent running troubles due to static electricity generated when the receiving sheet is run in the printer, or an image is formed. It may be added in the receiving layer or applied as a back coat.
A cationic hydrophilic polymer is effectively used as the antistatic agent.

[0023]

The present invention will be described in more detail with reference to the following examples. Of course, the scope of the present invention is not limited to these. All "parts" in the examples mean "parts by weight".

Example 1 A raw paper having a basis weight of 100 g / m ² , a density of 0.7 g / cm ³ and a smoothness of 20 seconds was made from a wood pipe having a freeness of 450 cc using a test paper machine. Next, a polyethylene resin containing 13% titanium dioxide was laminated on the front side of the base paper at a coating amount of 20 g / m ² , and a polyethylene resin without titanium dioxide was coated on the back side of the base paper at a coating amount of 20 g. It was laminated so that it would be / m ² . Finally, the surface of the resin coating layer is subjected to corona treatment, and then a receiving layer coating composition having the following composition is applied thereto by using a wire bar and dried to obtain an image receiving layer having a solid content of 6 g / m ^2. To form a receiving sheet.

The image-receiving layer coating composition Ingredient weight polyester resin 100 parts (trade Byron 200, Toyobo Co., Ltd.) silicone oil 3 parts (Trademark: KF393, produced by Shin-Etsu Silicon) isocyanate 5 parts (Trademark: Takenate D-110N, Takeda Pharmaceutical Co., Ltd.) Toluene 300 parts

Example 2 A receiving sheet was prepared in the same manner as in Example 1. However,
A base paper having a density of 0.9 g / cm ³ and a smoothness of 120 seconds was used as a support.

Example 3 A receiving sheet was prepared in the same manner as in Example 2. However,
A base paper obtained from wood pulp having a freeness of 560 cc was used as a support.

Comparative Example 1 A receiving sheet was prepared in the same manner as in Example 1. However, a base paper obtained from wood pulp having a freeness of 400 cc, a density of 0.8 g / cm ³ , and a smoothness of 60 seconds was used as a support.

Comparative Example 2 A receiving sheet was prepared in the same manner as in Example 1. However, a base paper having a density of 0.5 g / cm ³ and a smoothness of 60 seconds was used as a support.

Comparative Example 3 A receiving sheet was prepared in the same manner as in Example 1. However, a base paper having a density of 0.8 g / cm ³ and a smoothness of 140 seconds was used as a support.

Performance Evaluation A step pattern by a color bar signal generator (trademark: C13A2, manufactured by Shibazoku Co., Ltd.) was applied to the receiving sheets obtained in Examples 1 to 3 and Comparative Examples 1 to 3, and a dye thermal transfer printer (trademark: AG). -EP60, manufactured by Matsushita Electric Industrial Co., Ltd.). Table 1 shows the results of the sensory observation evaluation conducted for the print density unevenness and the presence or absence of the untransferred portion.

The sensory evaluation was carried out as follows. 3-level evaluation 3: Density unevenness, no untransferred area (excellent) 2: No density unevenness, untransferred area 1: No untransferred area, but uneven density

[0033]

[Table 1]

[0034]

EFFECTS OF THE INVENTION According to the present invention, it is possible to improve the density unevenness of a transferred image and obtain a dye thermal transfer receiving sheet excellent in print image quality at a low cost, which greatly contributes to the industrial world.

Claims (1)

[Claims] 1. A support containing cellulose pulp as a main component, a resin coating layer formed on one surface of the support and containing a thermoplastic resin as a main component, and formed on the resin coating layer. , And an image receiving layer that dyes and receives a thermal transfer image forming dye, and the support is formed of (1) cellulose pulp having a freeness of 450 cc or more as a main component, and (2) 0.7 to 0. A dye thermal transfer receiving sheet comprising a base paper having a density of 9 g / cm ³ and (3) a smoothness of 20 to 120 seconds.