JPH10157306A - Thermal transfer recording medium and thermal transfer recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain excellent repeatability of dot shape regardless of size of dot and form images of high definition by adding a coloring agent, a paraffin wax and a polyethylene wax which respectively have a number average molecular weight of a specified range in a heat fusion ink layer to be arranged on a substrate. SOLUTION: By using a thermal transfer record medium having a heat fusion ink layer arranged on a base material, the heat fusion ink layer is selectively heated and transferred to an image receiving body by a thermal transfer recording device so as to form images. A coloring agent, a paraffin wax having a number average molecular weight of 350-600 and a polyethylene wax having a number average molecular weight of 500-3000 are added in the heat fusion ink layer for forming images of high definition also on an image receiving body having high surface smoothness. At this time, the content of the paraffin wax in the heat fusion ink layer is set to 30-60wt.%, the content of the polyethylene wax is set to 2-20wt.%, and the coating quantity of the heat fusion ink layer is set within a range of 0.2-2.0g/m<2> .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a thermal transfer recording medium and a thermal transfer recording method using the same.

[0002]

2. Description of the Related Art Conventionally, using a thermal transfer recording medium having a thermal fusible ink layer provided on a substrate, the thermal fusible ink layer is selectively applied to an image receiving body such as paper by a thermal transfer recording apparatus equipped with a thermal head. A thermal transfer recording method of forming a printed image by heat transfer to a recording medium is widely used.

When a conventional thermal transfer recording medium having a heat-meltable ink layer mainly composed of wax on a base material is used to form an image on an image receiving body, the image receiving body is made of paper having a low surface smoothness. In such a case, there is a problem that the image is chipped or voided, and a high quality image cannot be obtained.

[0004]

The present inventors have studied and found that an image was formed on an image receiver having a high surface smoothness such as a coated paper or an OHP (overhead projector) film using the above-mentioned conventional thermal transfer recording medium. In such a case, there is a problem that when transferring a large dot, the connection of dots is generated and a good dot shape is not obtained, and when transferring a small dot, a non-transferred portion is generated, and there is a problem that image quality is deteriorated. There was found.

SUMMARY OF THE INVENTION In view of the foregoing, the present invention provides a thermal transfer method capable of forming a high-definition printed image with good dot shape reproducibility regardless of the size of the dot even on an image receiving body having a high surface smoothness. It is to provide a recording medium and a thermal transfer recording method.

[0006]

The present invention provides (1) a thermal transfer recording medium having a heat-meltable ink layer on a substrate,
The present invention relates to a thermal transfer recording medium, wherein the heat-fusible ink layer contains at least a colorant, a paraffin wax having a number average molecular weight of 350 to 600, and a polyethylene wax having a number average molecular weight of 500 to 3000.

Further, the present invention provides (2) a method wherein the content of the paraffin wax in the hot-melt ink layer is 30 to
60% by weight, the content of the polyethylene wax is 2
To 20% by weight of the thermal transfer recording medium according to the above (1).

In the present invention, (3) the coating amount of the hot-melt ink layer (in terms of solid content) is 0.2 to 2.0 g / m 2.
^2. The thermal transfer recording medium according to the above (1) or (2), wherein

The present invention further provides (4) the above (1) to
The present invention relates to a thermal transfer recording method using the thermal transfer recording medium described in any one of the above items (3) and forming a printed image on an image receiving body having a smooth surface by a thermal transfer recording apparatus equipped with a thermal head.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Paraffin wax and polyethylene wax have been conventionally used as a vehicle component of a hot-melt ink. In the present invention, the paraffin wax has a number average molecular weight of 350 to 60.
0, especially 350 to 550, and a polyethylene wax having a number average molecular weight of 500 to 3,000, especially 800 to 2,000, in combination with the heat-fusible ink. It has been found that, regardless of the size of the dot, the reproducibility of the dot shape is good and a high-definition printed image with excellent gloss can be formed.

However, when the number average molecular weight of the paraffin wax is less than the above range, the melting point of the heat-fusible ink becomes too low, and the dots are crushed during thermal transfer. On the other hand, when the number average molecular weight exceeds the above range, Insufficient sensitivity during thermal transfer. If the number average molecular weight of the polyethylene wax is less than the above range, good dot shape reproducibility cannot be obtained during thermal transfer. On the other hand, if the number average molecular weight exceeds the above range, the sensitivity during thermal transfer will be insufficient.

In the present invention, the content of the paraffin wax in the hot-melt ink layer is preferably 30 to 60% by weight, more preferably 40 to 40, in order to achieve the above-mentioned combined effect of paraffin wax and polyethylene wax.
50% by weight, the content of the polyethylene wax is 2 to
It is preferably 20% by weight, especially 5 to 10% by weight.

When the content of the paraffin wax is less than the above range, the transferability of the ink is inferior, and good dot shape reproducibility cannot be obtained. On the other hand, when the content exceeds the above range, the dots tend to be crushed during thermal transfer. . When the content of the polyethylene wax is less than the above range, good reproducibility of the dot shape is not achieved. On the other hand, when the content exceeds the above range, poor transfer tends to occur.

Further, in order to achieve the above-mentioned combined effect of paraffin wax and polyethylene wax well,
Coating amount of hot-melt ink layer (solid content converted value, the same applies hereinafter)
Is preferably set to 0.2 to 2.0 g / m ² .

If the amount of the hot-melt ink layer is less than the above range, good dot shape reproducibility cannot be obtained at the time of thermal transfer, while if less than the above range, the optical reflection density of a printed image tends to be insufficient.

As the vehicle component in the heat-fusible ink layer of the present invention, other waxes and / or thermoplastic resins can be used in addition to the paraffin wax and the polyethylene wax.

Examples of the waxes include natural waxes such as lanolin, carnauba wax, candelilla wax, montan wax and ceresin wax; petroleum waxes such as paraffin wax (other than the above-mentioned specific paraffin wax) and microcrystalline wax. Synthetic waxes such as oxidized wax, ester wax, polyethylene wax (other than the above specific polyethylene wax), Fischer-Tropsch wax, α-olefin-maleic anhydride copolymerized wax, and synthetic petroleum wax. Or two or more of them may be used in combination.

The above-mentioned thermoplastic resin (including elastomer)
Examples thereof include ethylene-vinyl acetate copolymer, ethylene-vinyl butyrate copolymer, ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid alkyl ester copolymer (the alkyl group is methyl, Examples thereof include those having about 1 to 16 carbon atoms such as ethyl, propyl, butyl, hexyl, heptyl, octyl, 2-ethylhexyl, nonyl, dodecyl, and hexadecyl), ethylene-acrylonitrile copolymer, ethylene-acrylamide copolymer, ethylene Ethylene copolymers such as -N-methylolacrylamide copolymer and ethylene-styrene copolymer; poly (meth) acrylates such as polylauryl methacrylate and polyhexyl acrylate; polyvinyl chloride, vinyl chloride-vinyl acetate Copolymer, vinyl chloride Vinyl chloride such as vinyl alcohol copolymer-based (co) polymers; other polyester resins,
Polyamide resin, epoxy resin, cellulosic resin, natural rubber, styrene-butadiene copolymer, isoprene polymer, chloroprene polymer and the like, and petroleum resin, rosin resin, terpene resin, cumarone-indene resin and the like or Two or more can be used.

Colorants used in the heat-meltable ink layer of the present invention include carbon black, azo pigments (insoluble azo, azo lake, condensed azo pigments), phthalocyanine pigments, nitro pigments, nitroso pigments, and anthraquinone pigments. Pigments, nigrosine pigments, quinacridone pigments,
Various organic and inorganic pigments such as perylene pigments, isoindolinone pigments, dioxazine pigments, and titanium white can be used. These pigments and dyes may be used in combination.

When a multi-color or full-color image is formed using subtractive color mixture, yellow, magenta, cyan and, if necessary, black pigments are used. Transparent organic pigments are preferably used as the yellow, magenta and cyan pigments. The opaque black pigment is usually used.

The content of the colorant in the hot-melt ink layer is suitably from 10 to 70% by weight.

The heat-fusible ink layer of the present invention may contain a dispersant, an antistatic agent, and the like, if necessary, in addition to the above components.

In the hot-melt ink layer of the present invention, the vehicle component is dissolved or dispersed in an appropriate solvent (including water),
Further, a coating liquid prepared by adding a colorant and, if necessary, other additives, and mixing well, is applied on a substrate, and dried to form a coating solution. Further, it can be formed by a hot melt coating method.

The substrate in the present invention includes polyester films such as polyethylene terephthalate film, polybutylene terephthalate film, polyethylene naphthalate film, polybutylene naphthalate film, polyarylate film, polycarbonate film, polyamide film, aramid film, and polyether film. Sulfone film, polysulfone film, polyphenylene sulfide film, polyetheretherketone film, polyetherimide film, modified polyphenyleneether film, polyacetal film, and various other plastic films generally used as base films for this type of ink ribbon Can be used. Also, high-density thin paper such as condenser paper can be used. The thickness of the substrate is usually 1 to 10 μm
And from the viewpoint of reducing the thermal diffusion and increasing the resolution, the range of 1 to 6 μm is preferable.

On the back surface of the substrate (the surface that is in sliding contact with the thermal head), a silicone resin, a fluororesin, a nitrocellulose resin, or various heat-resistant materials such as a silicone-modified urethane resin and a silicone-modified acrylic resin modified with these. It is preferable to provide a conventionally known stick prevention layer made of a resin, or a mixture of these heat-resistant resins with a lubricant.

In the thermal transfer recording medium of the present invention, if necessary, a release layer containing wax as a main component may be provided between the base material and the heat-meltable ink layer. An adhesive layer mainly composed of waxes may be provided on the layer, and a release layer and an adhesive layer may be provided together.

The present invention can be suitably applied not only to a thermal transfer recording medium for forming a monochromatic image but also to a color thermal transfer recording medium for forming a multi-color or full-color image utilizing subtractive color mixture. Things.

A thermal transfer recording medium for forming a single-color image has a single-color heat-meltable colored ink layer provided on a base material. The color of the hot-melt colored ink layer is black,
Red, blue, green, yellow, magenta, cyan, and the like.

As a color thermal transfer recording medium for forming a multicolor or full-color image, a yellow heat-meltable ink layer, a magenta heat-meltable ink layer and a cyan A heat-meltable ink layer and, if necessary, a black heat-meltable ink layer may be used.

In the thermal transfer recording method of the present invention, a printed image is formed on an image receiving body having a smooth surface by using a thermal transfer recording apparatus provided with a thermal head using the thermal transfer recording medium.

The image receiving body having a smooth surface is preferably one having a Beck smoothness of 1000 seconds or more. For example, a smooth surface of a base material such as coated papers, resin films, papers and the like is used. What laminated the resin layer etc. can be used. In an image receiving body having a surface smoothness lower than the above range, not only the reproducibility of the dot shape is poor, but also good gloss cannot be obtained.

In the thermal transfer recording method of the present invention, a conventional method can be employed without any particular limitation except for using the specific thermal transfer recording medium and the image receiving member. Even when a multi-color or full-color image is formed, the shape of the ink dot of the color transferred first on the image receiving body is good, and
Since the adhesiveness of the ink dots of the third and third transferred colors is good, good subtractive color mixing occurs and a good multi-color or full-color image is obtained.

[0033]

Next, the present invention will be described with reference to examples and comparative examples.

Examples 1 to 3 and Comparative Examples 1 to 6 A 3.5 μm-thick polyethylene terephthalate film having a stick-preventing layer made of a silicone-modified acrylic resin formed on the back surface was blended with the formulation shown in Table 1 The hot-melt ink prepared by melt-kneading the product was hot-melt coated on a letterpress coater to form a hot-melt ink layer having a coating amount of 1.5 g / m ² to obtain a thermal transfer recording medium.

The obtained thermal transfer recording medium was used in a thermal transfer printer (Color Point 2 PSFJ Model 14 manufactured by Seiko Denshi Kogyo KK) capable of changing the dot size, and an OHP film (polyethylene having a thickness of 75 μm) was used under the following conditions. An image was formed on a terephthalate film).

Printing energy: 0.38 W / dot Printing speed: 0.5 inch / second Printing pattern: gradation pattern (printing ratio changed from 5% to 100% (solid printing) by changing the size of one dot) (Printed Pattern) The printed image obtained on the OHP film was evaluated based on the following criteria.

4: The reproducibility of the dot shape is good regardless of the size of the dot, and the image is also good. 3: The reproducibility of the dot shape is somewhat poor, but there is no particular problem in the image in visual observation. 2: The reproducibility of the dot shape is poor, and the image has a grainy feeling. 1: The reproducibility of the dot shape is extremely poor, and the image has a jagged feeling.

[0038]

[Table 1]

[0039]

When the thermal transfer recording medium of the present invention is used, the reproducibility of the dot shape is excellent, regardless of the size of the dot, and the gloss is high and the definition is high even for an image receiving body having a high surface smoothness. An image can be formed.

Claims (4)

[Claims] 1. A thermal transfer recording medium having a heat-fusible ink layer on a substrate, wherein the heat-fusible ink layer has at least a colorant, a paraffin wax having a number average molecular weight of 350 to 600, and a number average molecular weight of 500. A thermal transfer recording medium, comprising: up to 3000 polyethylene wax. 2. The content of the paraffin wax in the hot-melt ink layer is 30 to 60% by weight, and the content of the polyethylene wax is 2 to 20% by weight. Thermal transfer recording medium. 3. The thermal transfer recording medium according to claim 1, wherein the amount of the heat-fusible ink layer applied (in terms of solid content) is 0.2 to 2.0 g / m ² . 4. A thermal transfer method using the thermal transfer recording medium according to claim 1, wherein a thermal transfer recording apparatus having a thermal head forms a printed image on an image receiving body having a smooth surface. Recording method.