JPS62227691A - Thermal transfer recording medium - Google Patents

Abstract

PURPOSE:To prevent a reduction in density of a dyestuff transferring image and a shortage of a printing image even after application of a large number of printing, by providing a resin layer, consisting of a rubber ingredient and a tackifier, between a substrate and a coloring material layer. CONSTITUTION:In a recording medium, a coloring material layer containing a hot-melt substance is provided on a substrate, and a resin layer consisting of a tackifier and at least one from among isoprene rubber, polyisobutylene, natural rubber, and styrene-butadiene rubber, is provided between the coloring material layer and the substrate. In this manner, in the medium, all the three forces, i.e. the adhesion between the resin layer and the coloring material layer, the cohesion in the resin layer, and the adhesion between the resin layer and the substrate, are respectively made larger than the cohesion in the coloring material layer, and this characteristics are kept after a large number of heat histories. Therefore, a low-energy printing can be conducted with high sensitivity and a dyestuff transferring image of high density can be obtained many times.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a thermal transfer recording medium that can be used many times, and an object of the present invention is to reduce the decrease in density with the number of times of use.
It is an object of the present invention to provide a thermal transfer recording medium that can be printed with low energy, has high sensitivity, and has high density and excellent resolution.

[Prior art]

As a thermal transfer recording medium intended for multiple uses, there is, for example, the invention described in Japanese Patent Application Laid-Open No. 54-68253. This invention is a technology in which a microporous layer is formed using a resin and the pores are impregnated with heat-sensitive 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 Energy is required, and even if a high-density dye transfer image is obtained by applying high energy,
There is a disadvantage that the edges of the printed image lack sharpness, and a technique similar to the above is disclosed in Japanese Patent Application Laid-open No. 55-105579, but the same disadvantage is observed.

Eliminate these shortcomings! 3 As a thermal transfer recording medium, JP-A-57-36698 discloses an ink layer (coloring material layer).
A technique is disclosed in which a resin layer made of polyvinyl butyral is interposed between the substrate and the support. Also, JP-A-6
0-127191 also discloses a technique using an ethylene-vinyl acetate copolymer instead of the polyvinyl butyral.

However, with these two technologies, although the adhesive strength between the color material layer and the support layer is slightly improved, the adhesive strength decreases significantly after thermal history, and is not suitable for the intended multiple printing. Problems such as a decrease in the density of the dye transfer image and defects in the printed image occur.

[Problem that the invention seeks to solve]

The problem to be solved by the present invention is to solve the above-mentioned difficulties of the conventional thermal transfer recording medium, especially a recording medium in which a specific resin layer is interposed between the coloring material layer and the support layer. be.

The present inventor has been conducting research based on the above-mentioned purpose, and in this research, it was discovered that the cause of the above-mentioned conventional difficulties lies in the resin layer, and it was found that the resin layer should be used between the coloring material layer and the support. It has been found that the following properties are necessary for the layer. That is, (i) the adhesive force between the resin layer and the coloring material layer, the cohesive force within the resin layer, and the adhesive force between the resin layer and the support.
According to the research of the present inventors, it is necessary that all of the above forces be larger than the cohesive force within the coloring material layer, and (ii) that the characteristics are maintained even after multiple thermal cycles. The technology was unable to maintain such characteristics, which resulted in defects in the intended multiple printing operations.

Therefore, to express the problem to be solved by the present invention using another expression, it is possible to improve the adhesion between the color material layer and the support, and to maintain the adhesion even after heat history. The goal of development is to develop a recording medium with this resin layer interposed therein.

[Means for solving problems]

The problem is that the support has a coloring material layer containing a heat-fusible substance, and a resin layer is interposed between the coloring material layer and the support! f
3. In the thermal transfer recording medium, this is achieved by the resin layer being a layer consisting of at least one fit of isoprene rubber, polyisobutylene, natural rubber, and styrene-butadiene rubber and a tackifier.

[Structure and operation of the invention]

In the present invention, the resin layer used between the coloring material layer and the support includes (a) isoprene rubber, polyisobutylene,
One or two of styrene-butadiene rubber and natural rubber
and (b) a tackifier. The resin layer having such a specific composition, that is, the above (a) and (b)
Preferably, the resin layer consisting of a specific blend of both of these is suitable for meeting (+) and (ii) of the above requirements.
Therefore, it is possible to perform low-energy printing, has high sensitivity, and has little loss of density with respect to the number of times it is used, making it possible to obtain high-density dye transfer images many times. This makes it possible to provide a heat-sensitive transfer recording medium that can be used.

The isoprene rubber used in the present invention includes 1
．． 4-polyisoprene can be used, and the molecular weight is usually preferably about 100,000 to 1,000,000.

A specific example is Cariflex Isoprene (Cari
flex l5opren: 5hell Chemi
cal), Ameriball SN (^meripol)
SN: Goodrich-Oulf), Philip P.
I (Philips PI: Ph1lips P
etroleum), etc.

Furthermore, the polyisobutylene used in the present invention generally has rubber elasticity and has a molecular weight of 6,000 or more. If it is less than 6,000, the adhesion between the colorant layer and the support tends to be poor. . Preferred specific examples include Vistanex MML-80, Vistanex MML-140, Oppanol B-10.
An example is 0.0ppanol B-200.

The natural rubber used in the present invention includes both natural rubber itself and slightly modified natural rubber. For the former, veil crepe is preferably used when transparency is required, and when color tone is not required, smoked sheet is preferably used, and for the latter, chlorinated rubber, cyclized rubber, M(, rubber, sp rubber, etc.) are used.

As the styrene-butadiene rubber used in the present invention, any conventionally known styrene-butadiene rubber can be used in a wide range, but from the viewpoint of adhesive strength, one with a low styrene content is preferable, and in particular, one with a styrene content of 5 to 40% is preferable. % is preferable. This rubber usually has a molecular weight of 10,000 to 1
About 1,000,000 is used, and a proso copolymer of styrene and butadiene is also effectively used.

The tackifier used in the present invention may generally be any resin that can be added to rubber to impart viscosity, such as raw rosin, hydrogenated rosin, hydrogenated rosin ester, β-
There are pinene resins, α-pinene resins, and terpene-phenol resins.

Further, various petroleum-based resins can be exemplified. More specifically, C9 petroleum resins include copolymer resins of indene, styrene, methylindene, and α-methylstin; C5 petroleum resins include copolymer resins of isoprene, cyclopentadiene, 1,3-pentadiene, and l-pentene; Examples of the dicyclopentadiene resin include dicyclopentadiene resin and copolymer resins of isoprene and 1,3-pentadiene.

In addition, commercially available tackifiers include gum rosin, ester gum H (Arakawa Chemical), P
olypale Ester 10 (Hercule
s).

As a polyterpene resin, YS resin A (cheap crude oil)
, Sumilight Resin PR12603 (Sumitomo Durez), and the like.

Examples of C2-based petroleum resins include Escoreso 1000 (Esso Chemical), Finton (Nippon Zeon), Tackirol (Sumitomo Chemical), and Tacace (Mitsui Petrochemical).

Examples of C9 petroleum resins include Betolite (Mikuni Resin Chemical) and Alcon (Arakawa Chemical).

Examples of dicyclopentadiene resins include Plccodience (Picco) and Escore.
z 8000 (Exxon) and the like.

The blending ratio of the rubber component (i) and the tackifier (ii) used in the present invention is not particularly limited, but preferably the tackifier is 30 to 90% by weight in the total resin layer weight%, and the rubber component (i) is 30 to 90% by weight. ) is preferably 70 to 10% by weight from the viewpoint of strong adhesion of the resin to the coloring material layer.

The technique of coating a resin layer on a support is known, and the resin layer of the present invention! ! For installation, these known techniques such as solvent coating can be used.

The thickness of the resin layer of the present invention is usually about 0.1 to 4 μm.

In the present invention, the coloring material layer is a layer containing a heat-melting substance.

The heat-melting substance used here may be any conventionally known heat-melting substance, but it is a solid or semi-solid substance with a melting point (measured by Yanagimoto MPJ-2 type) of 40 to 120°C. Preferred examples include plant waxes such as carnauba wax, wood wax, auriculie wax, and nispar wax; animal waxes such as silkworm wax, insect wax, cera owl and whale wax; paraffin wax, microcrystalline wax, and esters. In addition to waxes such as petroleum waxes such as wax and oxidized wax, and mineral waxes such as montan wax, osichelite, and ceresin, higher fatty acids such as 5-palmitic acid, stearic acid, margaric acid, and behenic acid;
Higher alcohols such as palmityl alcohol, stearyl alcohol, behenyl alcohol, marganyl alcohol, myricyl alcohol, eicosanol; higher fatty acid esters such as cetyl palmitate, myricyl palmitate, cetyl stearate, myricyl stearate; acetamide, propionic acid amide, palmitic acid amide,
Amides such as stearic acid amide and amide wax; ester gum, rosin maleic acid resin, rosin phenol resin, hydrogenated rosin and other rosin derivatives; phenolic resin,
Polymer compounds with a softening point of 50 to 120°C such as terpene resins, cyclopentadiene resins, and aromatic resins; Higher amines such as stearylamine, behenylamine, and palmitinamine; polyethylene oxides such as polyethylene glycol 4000 and polyethylene glycol 6000. These may be used alone or in combination, and among these, higher amides such as palmitic acid amide, stearic acid amide, oleic acid amide, and amide wax are particularly preferred.

The dye to be contained in the color material layer of the present invention may be appropriately selected from conventionally known dyes, such as direct dyes, acid dyes, basic dyes, disperse dyes, and oil-soluble dyes.

The pigment used in the present invention may be any pigment as long as it can be transferred (migrated) together with the heat-melting substance, so it may be a pigment in addition to the above. Specifically, the following can be mentioned.

That is, as yellow pigments, Kayalon Polyester Light Yellow 5G-3 (Northeast Japan), Oil Yellow S-7
(white clay), Eisenspiron GRH Special (Hodogaya), Sumiplast Yellow FG (Sumitomo), Eisenspiron Yellow GRH (Hodogaya), etc. are preferably used.

As a red pigment, Diaceritone Fast Red R (
Mitsubishi Kasei), Dianex Brilliant Red BS-
E (Mitsubishi Kasei), Sumiplus Trend FB (Sumitomo),
Sumiplast Tread HFG (Sumitomo), Kayalon Polyester Pink RCL-E (Northeast Japan), Eisens Viron Red GEH Special (Hodogaya), etc. are preferably used. Blue pigments include Diaceritone Fast Brilliant Blue R (Mitsubishi Kasei), Dianic Sprue EB-E (Mitsubishi Kasei), Kayalon Polyester Fil-B-3F Conc (Northeast Japan), Sumiplast Blue 3R (Sumitomo), Sumiplast Blue G (Sumitomo) and the like are preferably used.

In addition, as yellow pigments, Hansa Yellow 3G, Taldrazine Lake, etc. are used, as red pigments, brilliant carmine FB-Pure (deuterochrome), brilliant carmine 6B (deuterochrome), alizarin lake, etc. are used, and blue pigments are used. As the pigment, Cerulean Blue, Sumikablintocyanine Blue, N-0 (Sumitomo), Phthalocyanine Blue, etc. are used, and as the black pigment, carbon black, oil black, etc. are used. In addition,
Metal particles or gold-N oxide may also be used.

It is preferable that the coloring material layer of the present invention contains a resin for the purpose of increasing the adhesive strength between the coloring material layer and the resin layer.The resin used in the present invention has a softening point (measured by the ring and ball method) of 4.
It is preferably 0 to 200°C, and both hydrophilic and hydrophobic polymers can be used. Examples of hydrophilic polymers include gelatin, gelatin derivatives, cellulose derivatives, proteins such as casein, natural products and natural product derivatives such as polysaccharides such as starch, water-soluble polyvinyl compounds such as polyvinyl alcohol, polyvinylpyrrolidone, and acrylamide polymers. Examples include synthetic water-soluble polymers such as, vinyl-based and polyurethane-based polymer latexes. Examples of hydrophobic polymers include U.S. Pat. No. 3.142.586, U.S. Pat.
Examples include the synthetic polymers described in No. 287,289 and No. 3,411.911. Preferred polymers include polyvinyl butyral, polyvinyl formal, polyethylene, polypropylene, polyamide, ethyl cellulose, cellulose acetate, polystyrene, polyvinyl acetate, polyvinyl chloride, polyvinylidene chloride, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-malein. Examples include acid terpolymers, acrylic resins such as polymethyl methacrylate, polyisobutylene, rosin derivatives such as ester gums, and the like. In the present invention, one kind or a combination of two kinds of these resins are used.

Although the composition ratio of the coloring material layer of the present invention is not limited, the heat-melting substance is 50 to 90 parts and the coloring agent is 5 to 20 parts to the coloring material layer edge [1100 parts (parts by weight, same hereinafter)]. parts, and the resin is 30 parts or less (preferably 5 to 30 parts).

The color material layer of the present invention may contain known additives. For example, examples of the thermally conductive substance include metals with good thermal conductivity such as aluminum, copper, and zinc.

Such a thermally conductive substance promotes the heat conduction effect of melting, softening, or sublimating the coloring material layer by heat. Also, softeners such as oleic acid, castor oil, and dioctyl phthalate may be added.

In the thermal transfer recording medium of the present invention, the means for forming the coloring material layer on a support such as a polymer film via a resin layer is not particularly limited, and all conventionally known techniques can be used in the present invention. For example, the coloring material layer is a layer formed by true-melt coating of the composition, or by solvent coating a coating solution obtained by melting or dispersing the composition in an appropriate solvent. The coating method of the color material layer of the present invention includes reverse roll coater method,
Any known technique can be employed, such as an extrusion coater method, a gravure coater method, or a wire bar coating method.

The thermal transfer recording medium of the present invention may have other constituent layers such as an overcoat layer (for example, a layer made of a heat-fusible material).

Note that the support used as a base material for 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.

Heat resistance strength requires strength and dimensional stability to maintain the toughness of the support without becoming softened or plasticized by the heating temperature of a heat source such as a thermal head, and surface smoothness requires heat melting on the support. It is desired that the layer containing a sexual substance has sufficient smoothness to exhibit a good transfer rate. The smoothness is preferably 100 seconds or more in a smoothness test using a Beck tester (JIS P 8119), and when it is 300 seconds or more, images with better transfer rate and reproducibility can be obtained. Materials include, for example, papers such as plain paper, condenser paper, laminated paper, coated paper, resin films such as polyester, polycarbonate, polyethylene, polystyrene, polypropylene, polyimide, paper-resin film composites, aluminum foil, etc. metal sheets etc. are used. The thickness of the support is usually about 60 μm or less, particularly preferably 2 to 15 μm, in order to obtain good thermal conductivity. Furthermore, the thermal transfer recording medium of the present invention has a structure on the back side of the support. Optional.

〔Effect of the invention〕

The product of the present invention is characterized in that a resin layer consisting of (i) a rubber component and (ii) a tackifier is provided between the support and the coloring material layer, and this resin layer has adhesive strength with the coloring material layer. The three characteristics of the cohesive force within the resin layer and the adhesive force between the resin layer and the support are greater than the cohesive force within the coloring material layer, and do not change even after multiple thermal cycles. Compared to double printing ink sheets, there is no decrease in the density of the dye transfer image, and no scratches or the like occur in the printed image.

〔Example〕

Next, examples will be shown to explain the present invention in more detail.
The embodiments of the present invention are not limited thereto. Note that "parts" used below indicate "parts by weight."

Example 1 Styrene-butadiene rubber (Califlex TR-11
02; ShellChem) and 100 parts of a tackifier (Takki Roll 201; manufactured by Sumitomo Chemical) were dissolved in 1000 parts of toluene, and this solution was applied onto a 6 μm thick polyethylene terephthalate film support using a wire bar. After drying at 105° C. for 3 minutes, a resin layer with a thickness of 1 μm was formed. Next, 90 parts of paraffin wax,
A coloring material layer consisting of 10 parts of carnauba wax, 10 parts of ethylene-ethyl acrylate resin, and 25 parts of carbon black was coated on the resin layer at a thickness of 3 μm.

The heat-sensitive transfer recording medium sample of the present invention thus produced was layered on plain paper (white paper with a Bekk smoothness of 200 sec), and a thermal printer (with a heating element density of 8 dots/
Using a testing machine equipped with a+s+ thin film line thermal head, the energy applied to the sample was 0.5 mJ/do.
t was given and thermal transfer was performed. This was repeated 1 to 6 times.

Example 2 Styrene-butadiene rubber (Tsurprene 1205 HP
Phillips Petroleum) and 100 parts of a tackifier (Ester Gum H; Arayo Kagaku) were dissolved in 1000 parts of toluene, and then a sample was prepared in the same manner as in Example 1 and evaluated in the same manner.

Example 3 100 parts of isoprene rubber (Califlex TR-305, manufactured by Shell Chemical Co., Ltd.) and 120 parts of a tackifier (YS Resin A, manufactured by Yasushi Oil Co., Ltd.) were used, and the process was otherwise performed in the same manner as in Example 1. .

Example 4 Isoprene rubber (Natsyn2200, Tire &
Rubler Co., Ltd.) and 90 parts of a tackifier (Sumilight Resin PR12603, Sumitomo Duress Co., Ltd.) were used, and the other conditions were the same as in Example 1.

Example 5 100 parts of polyisobutylene (Vistanex MML-120, manufactured by Exxon) and a tackifier (Niscolec 10)
00 (manufactured by Exxon) and 120 parts, and the rest was treated in the same manner as in Example 1.

Example 6 The same treatment as in Example 1 was carried out except that 100 parts of polyisobutylene (Vistanex MML-80, manufactured by Exxon) and 100 parts of a tackifier (YS Resin A1, manufactured by Yasushi Oil Co., Ltd.) were used.

Example 7 100 parts of natural rubber (Bale crepe) and tackifier (Y
100 parts of S Resin A (manufactured by Kyuyu Yushi Co., Ltd.) was used, and the other conditions were the same as in Example 1.

Example 8 100 parts of chlorinated rubber and tackifier (Sumilight Resin PR)
12603, manufactured by Sumitomo Deeres Co., Ltd.) 100 copies,
The rest was treated in the same manner as in Example 1.

Comparative Example 1 A thermal transfer recording medium sample was prepared from Example 1 except that the resin layer was replaced with polyvinyl butyral (S-LEC BL-1, manufactured by Block Chemical Co., Ltd.), and tested in the same manner as in Example 1.

Comparative Example 2 A heat-sensitive recording medium was prepared by replacing the resin layer with ethylene-vinyl acetate (Evaflex P-2807, manufactured by Mitsui Polychemical Co., Ltd.) in Example 1, and tested in the same manner as in Example 1. did.

The results of thermal transfer of each of the above samples are shown in FIG.

As can be seen from the test results, the present invention causes a very small decrease in density compared to the conventional multi-print ink sheet.

However, the solid line (1) in FIG. 1 corresponds to Example 1.3.5.7.
Further, the solid line (2) shows the results of Example 2.4.6.8, the dotted line (3) shows Comparative Example 1, and the dotted line (4) shows Comparative Example 2.

[Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between reflection density and number of transfers.

Claims (1)

[Claims] (1) A thermal transfer recording medium having a coloring material layer containing a heat-melting substance on a support, and a resin layer interposed between the coloring material layer and the support, in which the resin layer is made of isoprene rubber, polyester, etc. A heat-sensitive transfer recording medium characterized by having a layer comprising at least one of isobutylene, natural rubber, and styrene-butadiene rubber and a tackifier.