JPH01258991A - Thermal transfer sheet - Google Patents

Abstract

PURPOSE:To improve reproducibility and saturation, by forming a thermally fusing ink layer area containing a fluorescent dye in addition to general dyes on one surface of a substrate film. CONSTITUTION:A thermally fusing ink layer area is formed by adding a suitable fluorescent dye to three primary colors, i.e. Yellow, Magenta, and Cyan, on one surface of a substrate film. Using this thermal transfer sheet the saturation of the aforesaid three primary colors of Yellow, Magenta, and Cyan is improved. In this manner, an image further superior in reproducibility and saturation is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to improvements in thermal transfer sheets, and more particularly to thermal transfer sheets suitable for forming color images.

(Prior art and its problems) Conventionally, when printing output prints from computers or word processors using a thermal transfer method, a thermal transfer sheet with a heat-melting ink layer provided on one side of a base film has been used. .

This conventional thermal transfer sheet uses a paper such as capacitor paper or paraffin paper with a thickness of 10 to 20 μm, or a plastic film such as polyester or cellophane with a thickness of 3 to 20 μm as a base film, and pigments or dyes are added to the wax. It is manufactured by coating a layer of hot-melt ink containing a colorant such as .

These thermal transfer sheets include 1.1.1. In addition, thermal transfer sheets of yellow, magenta, and cyan are known, and furthermore, as thermal transfer sheets for forming full-color images from these thermal transfer sheets, three primary colors of yellow, magenta, and cyan are applied to a continuous or sheet base film. Alternatively, a full-color thermal transfer sheet is known in which ink layer regions of four primary colors including black are sequentially formed.

When forming a color image using these thermal transfer sheets, three or four color separated images are superimposed and transferred onto the same side of the same transfer material, and the colors are mixed by subtractive color mixing on the transfer material 42. Because it involves the synthesis of three primary colors, the three primary colors are required to be as transparent as possible and as highly saturated as possible. The higher the transparency and saturation of each color, the more faithful the image will be to the original.
The conventionally used yellow, magenta and cyan pigments have a certain limit in their saturation, and therefore there is also a certain limit in the level of chroma and saturation of the 11F image.

Accordingly, an object of the present invention is to provide a thermal transfer sheet that can produce color images with better printability and saturation than ever before.

(Means for solving problems) The above objective 1] is achieved by the following present invention.

That is, in the present invention, on one side of the L-material film,
This is a thermal transfer sheet characterized by forming a heat-fusible ink layer region in which a fluorescent dye is added to a general dye.

(Function) By adding appropriate fluorescent dyes to the three primary colors of yellow, magenta and cyan to improve their saturation,
Furthermore, a thermal transfer sheet is provided that provides color images with excellent color reproducibility and saturation.

(Preferred Embodiments) Next, the present invention will be explained in more detail with reference to preferred embodiments.

The thermal transfer sheet of the present invention has three colors of yellow, magenta and/or cyan on one side of a continuous or sheet base film.
It is created by adding a fluorescent dye to the primary color to form a hot-melt ink layer.

The base film used in the present invention may be a continuous or sheet film similar to that used in conventional thermal transfer sheets.
The material film can be used as it is, and other materials can also be used, and the material is not particularly limited to 1t11.

Specific examples of preferred base films include polynisder, polypropylene, cellophane, polycarbonate, cellulose butyrate, polyethylene, polyvinyl chloride,
Polystyrene, nylon, polyimide, polyvinylidene chloride, polyvinyl alcohol, fluororesin, chlorinated rubber,
Examples include plastics such as ionomers, papers such as condenser paper and paraffin paper, nonwoven IH+, and base films made of composites of these materials.

The thickness of the material film can be changed depending on the material so that its strength and thermal conductivity are appropriate, but the thickness is preferably, for example, 2 to 25
It is μm.

When the base film is a continuous film, the yellow, magenta, and cyan hot-melt ink layers containing fluorescent dyes have an area corresponding to the A4 size, for example, when forming a color image on an A4 size. Areas of these tones may be formed in a plane-sequential manner according to a conventional method.

As the yellow, magenta and cyan dyes, conventionally known dyes can be used as they are, and as the fluorescent dye, fluorescent dye ff1I is prepared by dissolving a known fluorescent dye in a thermosetting resin and curing it, and pulverizing this into an appropriate particle size. Fluorescent dye materials and their original fluorescent dye sleeves are known, such as Evocolor FP3000 (fluorescent yellow), Epocolor FP20 (fluorescent pink), Epocolor FP115 (fluorescent orange), and Evocolor FP1007 (fluorescent green).
, Shinroihi Color FA4B (fluorescent blue), Fire Orange AX-14-5, Glow Red Powder, etc. are commercially available and can be used in the present invention. Furthermore, the fluorescent dyes used in the above-mentioned fluorescent pigments can also be used manually and manually.

Use of these fluorescent dyes (it is conventionally known yellow,
Approximately 0.0% per 111 parts by weight of magenta and cyan pigments.
It is preferable to use the amount of 1il part to 50 parts by weight.If the amount used is less than the above range, the effect of adding the fluorescent dye will be insufficient.On the other hand, if the amount used exceeds the above range, the fluorescent dye This is not preferable because the color becomes too strong and the color rendering properties of the original dye deteriorate. Further, it is preferable to use a yellow fluorescent dye for the yellow pigment, a red to pink fluorescent dye for the magenta pigment, and a blue to green fluorescent dye or fluorescent whitening dye for the cyan pigment. It is generally preferred that the total amount of these pigments be used in the ink in a proportion of about 2 to 90 +rC@%.

As in the case of conventional yellow, magenta and cyan, the main component of the vehicle is wax, and mixtures of wax with drying oil, resin, mineral oil, cellulose, rubber derivatives, etc. are used as typical examples of wax. teeth,
Microcrystalline wax, carnauba wax, paraffin wax, etc. In addition, Fischer-Tropsch wax, various low-molecular-weight polyethylenes, wood wax, beeswax, spermaceti wax, privet wax, wool wax, shellac wax, candelilla wax, petrolactam, polyester wax, polyester wax, fatty acid ester, fatty acid amide, etc. Various waxes are used.

The present invention further provides heat Ii having a relatively low melting point in the wax.
By mixing T plastic resin, it is possible to improve the adhesion of the formed ink layer to the transfer material. Such thermal IiT plastic resins include, for example, ethylene-vinyl acetate (EV^), ethylene-acrylic acid ester copolymer ([EEA), polyethylene, polystyrene, polypropylene, polybutene, petroleum resin, chloride Vinyl resin, vinyl chloride-vinyl acetate copolymer, polyvinyl alcohol, vinylidene chloride resin, methacrylic resin, polyamide, polycarbonate, fluororesin, polyvinyl formal, polyvinyl butyral, acetylcellulose, nitrocellulose, polyvinyl acetate, polyisobutylene, ethylcellulose , polyurethane or polyacetal, and in particular those having a relatively low softening point, such as 20 to 80°C, preferably 50 to 80°C, which are conventionally used as heat-sensitive adhesives, are preferred.

The ratio of the wax to the thermoplastic resin is preferably in the range of 5 to 300% of the thermoplastic resin to 100% of the wax.

To form the ink layer, a method can be used in which a mixture containing the above components is melted and liquefied and then applied, or a method in which the above components are dissolved and dispersed in a suitable solvent to form an ink, which is then applied and dried. Coating methods include hot melt coating, hot lacquer coating, gravure coating, gravure reverse coating, roll coating, and many other methods. Note that hot melt coating may cause thermal deterioration of the fluorescent pigment due to insufficient heat resistance, etc., so it is preferable to form the ink layer using a solvent type ink.

In the present invention, a surface layer can also be formed on the ink layer. This surface layer forms a part of the transfer film during thermal transfer, and is formed mainly of wax as described above.

The surface layer may be formed by hot-melt coating or the like in the same way as the ink layer, but a preferred method is to use an aqueous dispersion containing wax. A particularly preferred method is to apply an aqueous dispersion of wax onto the hot-melt ink layer and dry it at a temperature equal to or higher than the melting point of the wax.

By doing this, the wax forms a surface layer while maintaining its particle shape.

The aqueous medium containing the wax is water or a mixture of water and a water-soluble organic solvent, such as methanol, ethanol, isopropanol, and the water-soluble organic solvent is mixed
By using 1 part of 5 to 200ffiq per 00 parts by weight, the wettability of the wax aqueous dispersion to hot-melt ink is improved.Furthermore, the wax aqueous dispersion may contain a low kt emulsifier (surfactant), a leveling agent, etc. Known additives can be included. The solid content of this dispersion is approximately 10
The amount is about 501% to 501%.

In the present invention, the above-mentioned dispersion further includes a thermoplastic having a relatively low melting point as described above! It is possible to improve the adhesion of the formed surface layer to the rolled 7f material by mixing the iv resin. The ratio of wax to thermoplastic resin is 100% wax.
Thermoplastic resin has a value of 5 to 300
A range of ratios is preferred.

The surface layer formed from the above-mentioned wax is formed by applying an ink composition containing wax by a conventionally known coating method and drying. , a smooth surface layer is formed,
On the other hand, if the wax is dried at a temperature lower than the melting point of the wax, a surface layer having a finely uneven surface in which the particle shape of the dispersion remains is formed.

In the present invention, the thickness of the surface layer formed as described above is preferably 0.1 μm or more and 5 μm so that sensitivity will not be insufficient even when the printing energy is low as in a high-speed printer. less than If the thickness is less than 0.1 μm, there is a risk that the transfer paper and the ink layer will rub against each other, resulting in scumming. The surface layer 1 is substantially uncolored after thermal transfer, and may be colored white by adding an appropriate amount of extender pigment or white pigment.

When a heat-sensitive material is used for the base film, it is preferable to provide a layer on the surface in contact with the thermal head to prevent sticking of the thermal head. The basic components of the anti-sticking layer are a heat-resistant resin and a substance that acts as a heat-resistant molding agent or lubricant. Heat-resistant resins include synthetic resins with a glass transition point of 60°C or higher, or thermoplastic resins having OH groups or COOH groups, which are slightly cross-linked by adding a compound having two or more amino groups, or diisocyanate or triisocyanate. Those that have been cured are preferred. Heat release agents or lubricants include those that melt when heated, such as waxes and higher fatty acid amidonisdel and salts, and those that remain solid, such as fluororesin and inorganic substance powders. be.

By providing such an anti-sticking layer, thermal printing can be performed on 11 pages without causing sticking even on thermal transfer sheets based on heat-sensitive plastic films, and the resistance to cutting and processing of plastic films can be improved. Benefits such as ease of use can be taken advantage of.

Heat-transferred images generally have glossy prints and are beautiful, but on the other hand, the text (-) may be difficult to read, so matte prints are recommended! Something bad happened. In such a case, for example, as proposed by the applicant (Japanese Patent Application No. 58-2011306), an inorganic pigment such as silica or calcium carbonate may be dispersed in a suitable solvent on a base film. It is preferable to form a thermal transfer sheet by coating a matte layer by coating and then coating the layer with a heat-melting ink layer.

Alternatively, the base film itself may be matted and used (see also Patent Application Sho! 18-208 proposed by the applicant).
: No. 107 technology).

The thermal transfer sheet of the present invention as described below can be applied to any type of thermal transfer printer, such as a commercial line or serial type printer.

(Effects) According to the present invention as described above, by adding an appropriate fluorescent dye to the three primary colors of yellow, magenta and cyan to improve their saturation, color II [appearance and saturation] can be further improved. A thermal transfer sheet is provided that provides excellent color images.

(Example) Hereinafter, the present invention will be explained in more detail with reference to Examples.

In addition, unless otherwise specified, the words "part" or "%" in the text refer to weights.
It is quasi-ltM.

Example 1 A continuous film of polyethylene terephthalate with a thickness of 3.5 μm was used as a base film, and one side of the film was coated with three colors of hot-melt ink having the following composition and dried, and then a surface layer material was coated. and dried to obtain a thermal transfer sheet of the present invention.

X-part ethylene /
24 parts paraffin wax (paraffin IINF-10, 21 pieces made from rust wax)
42 parts carnauba wax 1
4 parts Kijirol 153.8 parts Isopropyl alcohol 31 parts Yellow color Yellow pigment 8 parts Fluorescent yellow (Epocolor FP
3000) 16 parts ヱ Y Noshi Red pigment 8 parts Fluorescent pink pigment (Evocolor-1・1) 20) 16 parts 2ヱ2 RF color pigment 8 parts Fluorescent green pigment (Evocolor FPI007) 16 parts Using an attritor, add enough Using the gravure roll coating method, the material was coated in yellow, magenta, and cyan in the order of yellow, magenta, and cyan, one after the other, on an A4 plate and dried. I let it happen.

K-face Moon 155F Parafine Wax Emulsion (IIE-7
5. Manufactured by Bond Wax Co., Ltd., solid content 40% aqueous emulsion B
) 20 parts ionomer resin (Chemivar S-100, Nil Petrochemical, solid content 27%)
10 parts 60% isopropanol aqueous solution
It was applied to the surface of the ink layer at a rate of 0.8 g/m'' (dry state) using a 15-part Clavia coating method and dried at 60° C. to form a matte surface layer.

When a full-color image was reproduced using the above thermal transfer sheet, F-grade paper as the transfer paper, and a thermal head, the saturation of the entire image was lower than in the comparative example below. and excellent color reproducibility.

Comparative Example 1 A thermal transfer sheet of the present invention was prepared in the same manner as in Example 1 except that no fluorescent dye was used in Example 1 (1+).

Using the above thermal transfer sheet, transfer 'I3: as paper] -
A full-color image was reproduced using a commercially available thermal head using synthetic paper.

Patent applicant: [Ippon Printing Co., Ltd.

Claims (1)

[Claims] (1) A thermal transfer sheet characterized in that a heat-fusible ink layer containing a fluorescent dye added to a general dye is formed on one side of a base film.