JPH041714B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a thermal transfer recording medium that can be used multiple times. Specifically, the present invention relates to a thermal transfer recording medium that exhibits little density loss with use, is capable of printing with low energy, is highly sensitive, and provides uniform printing with high density and excellent resolution.

[Prior Art] As a thermal transfer recording medium intended for multiple uses, there is, for example, an invention described in Japanese Patent Application Laid-Open No. 54-68253. This invention is a technology in which a microporous layer is formed using resin and the pores are impregnated with thermal ink, but the density of the dye transfer image is low, and in order to obtain a high density dye transfer image, it is necessary to , high energy is required, and even if a high density dye transfer image is obtained by applying high energy, the edges of the printed image lack sharpness. JP-A-55-105579 and JP-A-57-36698 also disclose techniques similar to the above, but they have the same drawbacks.

In addition to the above, heat-sensitive transfer recording media that can be used many times using various techniques are being considered. for example,
As shown in JP-A No. 57-185195, a method of grafting a vinyl monomer onto carbon black; as shown in JP-A No. 55-55887, a method of roughening the ink layer side of the support. , 57−
As shown in Japanese Patent Nos. 138984 and 58-116193, there are known ones in which an intermediate layer for adhesion is provided between the base material and the ink layer. These prevent all of the colorant from being transferred at once when heated with a thermal head, and although each of them is effective to some extent, it is still insufficient.

[Objective of the Invention] The object of the present invention is to enable low-energy printing, to have high sensitivity, and to have little loss of density with respect to the number of uses, so that high-density dye transfer images can be obtained many times. An object of the present invention is to provide a thermal transfer recording medium.

Another object of the present invention is to provide a thermal transfer recording medium that allows uniform printing even when printing a solid image.

Other objects of the invention will become apparent from the following description of the specification.

[Summary of the Invention] As a result of intensive research, the present invention provides a thermal transfer recording medium having a coloring material layer on a support containing a resin, a coloring agent, and a solid component that is solid at room temperature. It has been found that the above object can be achieved when the resin component is at least one of ethylene-alkyl acrylate copolymer or ethylene-alkyl methacrylate copolymer, and the solid component is paraffin wax. , led to the present invention.

[Structure of the invention] The present invention will be explained in more detail below.

The thermal transfer recording medium of the present invention has at least one coloring material layer on a support, and the coloring material layer contains at least one kind of resin, one kind of colorant, and one kind of solid component.

The resin component used in the present invention is at least one type of ethylene-alkyl acrylate copolymer or ethylene-alkyl methacrylate copolymer (hereinafter referred to as the polymer of the present invention).

The alkyl in the polymer of the present invention is a linear or branched alkyl having 1 to 18 carbon atoms, and the copolymerization ratio of ethylene and alkyl (meth)acrylate is preferably in the range of 95/5 to 20/80. , and those with a softening point (measured by the ring and ball method) of 200℃ or less,
Particularly preferred is a temperature of 50 to 200°C.

Specific examples of the polymer of the present invention include ethylene-
Ethyl acrylate copolymer, ethylene-propyl acrylate copolymer, ethylene-n-butyl acrylate copolymer, ethylene-isobutyl acrylate copolymer, ethylene-octyl acrylate copolymer, ethylene-stearyl acrylate copolymer, etc., and ethylene - Ethyl methacrylate copolymer, ethylene-propyl methacrylate copolymer, ethylene-n-butyl methacrylate copolymer, ethylene-isobutyl methacrylate copolymer, ethylene-octyl methacrylate copolymer, ethylene-stearyl methacrylate copolymer, etc. can be mentioned.

Furthermore, conventionally known resins may be used in combination, but in this case, it is preferable that the polymer of the present invention is contained in an amount of 50% or more (wt%, the same applies hereinafter) of the total resin,
In particular, the content is preferably 70% or more.

The solid component used in the present invention is a paraffin wax. The paraffin wax has a melting point (value measured by Yanagimoto MPJ-2 type) of 45 to 100°C.
This wax is mainly composed of straight-chain and branched hydrocarbons, and is generally called paraffin wax, microcrystalline wax, etc. The paraffin wax of the present invention is easily available from commercial products, such as paraffin wax 145, paraffin wax 150, paraffin wax 155, HI-MIC-1070,
HI-MIC-1080, HI-MIC-2065, HI-MIC-
2045, HI-MIC-2095, HI-MIC-1045 (manufactured by Nippon Seirosha), STAR WAX 100, BE
SQUARE 175, 185, VICTORY,
Commercially available products include ULTRAFLEX (manufactured by Toyo Petrolite Co., Ltd.), Nisseki Microwax 155, and ULTRAFLEX 180 (manufactured by Nippon Oil Co., Ltd.).

In addition, other conventionally known solid components that are solid at room temperature, such as carnauba wax, ester wax, stearic acid, stearic acid monoglyceride, pentaerythritol stearate, stearyl alcohol, fatty acid amide (such as lauric acid amide, myristic acid amide), etc. , heat-fusible fatty acid amides such as paramitic acid amide, stearic acid amide, oleic acid amide, etc.) may be used in combination.
In this case, it is preferable that the paraffin wax of the present invention is contained in an amount of 50% or more in the total solid components. In particular, the content is preferably 70% or more.

As the colorant in the present invention, conventionally known colorants can be used without any particular limitations. That is, the coloring agent of the present invention may be appropriately selected from conventionally known pigments, including direct dyes, acid dyes, basic dyes,
You may choose from disperse dyes, oil-soluble dyes, etc. The coloring matter used in the coloring material layer of the present invention may be any pigment that can be transferred (transferred) together with the heat-melting substance, and may be a pigment in addition to the above. In addition, specifically, the following can be mentioned. In other words, the yellow pigment is Kayalon Polyester Light Yellow.
5G-S (Nippon Kayaku), Oil Yellow S-7 (white clay), Eisenspiron GRH Special (Hodogaya), Sumiplast Yellow FG (Sumitomo), Eisenspiron Yellow GRH (Hodogaya), etc. are suitable. used. Red pigments include Diaceriton Fastred R (Mitsubishi Kasei), Dianics Brilliant Red BS-E (Mitsubishi Kasei), Sumiplast Stretch FB (Sumitomo), and Sumiplast Stret HFG.
(Sumitomo), Kayalon Polyester Pink RCL-E
(Nippon Kayaku), Eizenspiron Red GEH Special (Hodogaya), etc. are preferably used. As blue pigments, Diaceritone Fast Brilliant Blue R (Mitsubishi Kasei), Dianics Blue
EB-E (Mitsubishi Kasei), Kayalon Polyester Blue B-SF Conc (Nippon Kayaku), Sumiplast Blue 3R (Sumitomo), Sumiplast Blue G (Sumitomo), etc. are preferably used. In addition, Hansa Yellow 3G, Tartrazine Lake, etc. are used as yellow pigments, and brilliant carmine is used as red pigments.
FB-Piure (Sanyo Dyes), Brilliant Carmine 6B (Sanyo Dyes), Alizarin Lake, etc. are used, and as blue pigments, Cerulean Blue, Sumikaprint Cyanine Blue GN-O (Sumitomo), Phthalocyanine Blue, etc. are used, and black As the pigment, carbon black, oil black, etc. are used. In addition, metal particles or metal oxides may also be used.

Although the composition ratio of the coloring material layer of the present invention is not limited,
It is preferable that the amount of the polymer of the present invention is 1 to 60 parts (by weight, the same applies hereinafter), the paraffin wax is 10 to 80 parts, and the colorant is 5 to 40 parts.

In the thermal transfer recording medium of the present invention, techniques suitable for applying the coloring material layer to a support such as a polymer film are known in the art, and these techniques can also be used in the present invention. For example, the coloring material layer is a layer formed by hot melt coating the composition or by solvent coating a coating solution prepared by dissolving or dispersing the composition in an appropriate solvent. As a method for applying the coloring material layer of the present invention, any known technique can be employed, such as a reverse roll coater method, an extrusion coater method, a gravure coater method, and a wire bar coating method. The color material layer of the present invention may have a thickness of 20 μm or less, preferably 3 to 15 μm.

Note that the support used in the thermal transfer recording medium of the present invention is preferably a support that has heat-resistant strength, high dimensional stability, and high surface smoothness. Materials include, for example, papers such as plain paper, condenser paper, laminated paper, coated paper, resin films such as polyethylene, polyethylene terephthalate, polystyrene, polypropylene, polyimide, paper-resin film composites, aluminum foil, etc. A metal sheet or the like can also be suitably used. The thickness of the support is usually approximately
It is preferably 60 μm or less, particularly 2 to 20 μm.

Furthermore, in the thermal transfer recording medium of the present invention, the structure of the back side of the support is arbitrary.

The thermal transfer recording medium of the present invention may have other constituent layers such as an undercoat layer (for example, a layer for improving film adhesion).

[Effects of the Invention] According to the present invention, the coloring material layer of the present invention substantially Even though it is a continuous layer and has a thin film thickness, it is possible to obtain a uniform, high-density dye transfer image many times, and moreover, it exhibits the effect of obtaining a high-resolution dye transfer image.

[Example] Examples are given below, but the embodiments of the present invention are not limited thereto. Note that "parts" used below indicate "parts by weight."

Example 1 A coloring material layer composition having the following composition was deposited on a 6 μm thick polyethylene terephthalate film support in a film thickness of 5 μm.
A sample of the thermal transfer recording medium of the present invention was obtained by coating the film in an amount of m.m.

Coloring material layer composition (a) Microcrystalline wax (ULTRAFLEX, manufactured by Toyo Petrolite Co., Ltd.) (melting point
65℃) 68 parts ethylene-ethyl acrylate copolymer (NUC)
-6070, manufactured by Nippon Unicar Co., Ltd.) (polymerization ratio 75/25, softening point 95°C) 17 parts carbon black 15 parts A thermal printer (heating element density
A prototype machine equipped with an 8dot/mm thin film line thermal head. ) was used to apply an energy of 0.60 mJ/dot to record (print) a solid image and a checkered pattern on plain paper. This was repeated 1 to 5 times. In addition,
Commercially available high-quality paper (80 g/m ² ) was used as the plain paper. As a result, uniform and high-resolution recorded images were obtained each time. The gloss reflection density of the recorded image (the value measured by the light reflection density of the printed dye transfer image using a reflection densitometer (manufactured by Konishi Roku Photo Industry Co., Ltd.)) is 1.48, 1.31, 1.25, 1.08, 1.08, It was 0.90.

Comparative Example 1 A comparative thermal transfer recording medium sample was prepared in the same manner as in Example 1 except that carnauba wax was used instead of microcrystalline wax, and printing was performed in the same manner. Transcribed. The printing energy is 0.62mJ/
It was dot.

Comparative Example 2 A comparative thermal transfer recording medium prototype was prepared in exactly the same manner except that the copolymer of Example 1 was replaced with a vinyl chloride-vinyl acetate copolymer, and printing was performed in the same manner. occurred, making it impractical for practical use.

Comparative Example 3 According to Example 1 of JP-A-54-68253,
A coating solution consisting of 10 parts of vinyl chloride/vinyl acetate copolymer, 7 parts of carnauba wax, 11 parts of castor wax, 4 parts of carbon black, 51 parts of ethyl acetate, and 17 parts of toluene was applied to various coatings on the same support as the sample. Several samples of thermal transfer recording media were obtained by solvent coating with varying film thickness and processing as described in the publication. When each of these samples was printed on plain paper in the same way as the samples, the thickness of the color material layer was 5 μm.
However, in order to obtain a relatively uniform printed image, the thickness of the coloring material layer was required to be 10 μm or more. Also, the applied energy at this time is
It was 0.90 mJ/dot, and the reflection density of the recorded image when printed many times was extremely thin at 0.83 from the first printing, and was 0.75, 0.70, and 0.50 at the second printing.

Comparative Example 4 According to the example of JP-A-55-105579, 20 parts of vinyl chloride/vinyl acetate copolymer, 40 parts of common salt,
A coating solution consisting of 2 parts of p,p-oxy-bis(benzenesulfonyl hydrazide), 60 parts of methyl ethyl ketone, and 40 parts of heptane was solvent coated onto the same support as the sample and then coated as described in the example. Processing yielded a sample of a thermal transfer recording medium having a microporous ink layer.

Regarding this sample, repeated printing was attempted on plain paper in the same manner as the above sample. However, from the first print, only a dye transfer image with a density too low to be of practical use was obtained. Furthermore, using this sample, to obtain a transfer density comparable to that of the dye transfer image obtained using the sample of the present invention, approximately 2.4 times as much applied power was required. Moreover, the sharpness of the edges of the dye transfer image obtained from the sample was several orders of magnitude worse than that of the sample of the present invention.

Claims (1)

[Claims] 1. In a thermal transfer recording medium having a coloring material layer containing a resin, a coloring agent, and a solid component that is solid at room temperature on a support, the resin component in the coloring material layer is an ethylene-alkyl acrylate copolymer or an ethylene-alkyl acrylate copolymer. A multiple thermal transfer recording medium comprising at least one alkyl methacrylate copolymer and a solid component comprising a paraffin wax.