JPH06286330A - Heat-sensitive recording medium - Google Patents

Abstract

PURPOSE:To form a picture having the excellent shelf life by avoiding the occurrence of corrosion in a thin metal film layer even if a black-colored layer is formed in a destruction-type heat sensitive recording medium, which is formed by sequentially laminating a base material, a colored layer, a heat sensitive sensitization layer, the thin metal film layer and a protecting layer. CONSTITUTION:In a heat-sensitive recording meium, which is formed by sequentially laminating a base material 1, a colored layer 2, a heat sensitive sensitization layer 3, a thin metal film layer 4 and a protecting layer 5, the colored layer is formed of black paint containing a black coloring agent, wherein yellow, Mazenta and cyanogen coloring agents are mixed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording medium capable of forming a clear image on itself by being selectively heated according to image information by a heating means such as a thermal head.

[0002]

2. Description of the Related Art A thermal energy from a heating means such as a thermal head or a laser beam causes a chemical change or a physical change in a thermal recording medium to produce a prepaid card,
A thermal recording method for forming an image on an image-formed body such as a pass ticket, an admission ticket, a boarding ticket, a facsimile sheet, a computer output sheet, and a tape-like or sheet-like form is widely used. In the case of image recording, it can be roughly divided into two methods from the viewpoint of whether or not an auxiliary material is required in addition to the image-transferred body.

First, the first method requiring auxiliary materials is
In this method, a heat-sensitive transfer ribbon having a wax-based ink layer as an auxiliary material is used, and the ink layer of the ribbon is transferred to the image-receiving layer of the image-receiving member by heating. This method has good storability of the obtained image, can use general papers and the like as an image-formed body, and has advantages such as easy colorization of the image. It is used when outputting data and when recording color images with a color printer.

However, the first method requires the use of an auxiliary material called a heat-sensitive transfer ribbon, so that there is a problem that the image forming cost cannot be sufficiently reduced.

On the other hand, the second method, which does not require auxiliary materials, is one in which a heat-sensitive recording layer containing a leuco dye such as a fluoran dye as a color former is provided as an image-receiving member. In this method, an image is directly formed on the image forming body by heating the image forming body. This method can form an image at a relatively low temperature because the leuco dye has good thermal sensitivity, does not use auxiliary materials such as a thermal transfer ribbon, and does not require a transfer system for the thermal transfer ribbon in the printer. Therefore, there is an advantage that an image can be formed at low cost. Therefore, this second method is widely used for data output of facsimiles and word processors where it is desired to form an image at low cost.

However, in the second method in which a leuco dye is used as a color former without using auxiliary materials, image fogging occurs due to too good thermal sensitivity, and color development is relatively easy due to unintended pressure. However, there is a problem that the quality of the image deteriorates. Further, there is also a problem that the color is easily changed when contacted with a polar organic solvent such as alcohol. In this way, the second method using the leuco dye as a color former is to improve the chemical resistance of the obtained image,
Since the environment resistance such as light resistance, water resistance, and heat resistance is not sufficient, it has been used only for the purpose of temporarily forming an image.

Therefore, as a method of forming an image having good storage stability without using auxiliary materials, a heat-sensitive recording medium having a metal thin film layer having a hiding property and a colored layer containing carbon black as an underlying layer is used. , This metal thin film layer is heated so that the heated portion of the metal thin film layer contracts and breaks to lose the concealing property, and an image is formed by making the colored layer underneath visible. A third method has been proposed.

The structure of the heat-sensitive recording medium used in the third method includes a substrate such as a polyester film, a coloring layer containing carbon black, a heat-sensitizing layer made of a thermoplastic resin, and vacuum deposition of tin or aluminum. It is proposed that the metal thin film layer and the protective layer such as a transparent polyester film are sequentially laminated.

[0009]

However, in the heat-sensitive recording medium utilizing the contraction destruction phenomenon due to the heating of the metal thin film layer, the carbon thin film is corroded because carbon black is used as the black pigment. There was a problem. The cause of this is not clear, but it is considered that, since carbon black has high conductivity, electricity from the outside is conducted to the metal thin film layer, which causes corrosion to the metal thin film layer.

The present invention is intended to solve the above problems of the prior art, and is a heat-sensitive recording in which a substrate, a coloring layer, a heat-sensitizing layer, a metal thin film layer and a protective layer are sequentially laminated. An object of the present invention is to make it possible to form an image with good storability without causing corrosion in the metal thin film layer even when a black colored layer is formed in the medium.

[0011]

The inventor of the present invention uses, as a black colorant to be contained in a colored layer, a mixture of yellow, magenta and cyan colorants having significantly lower conductivity than carbon black. As a result, they have found that the above object can be achieved, and have completed the present invention.

That is, according to the present invention, in a heat-sensitive recording medium in which a base material, a coloring layer, a heat-sensitizing layer, a metal thin film layer and a protective layer are sequentially laminated, the coloring layer mixes yellow, magenta and cyan colorants. There is provided a heat-sensitive recording medium containing the above black colorant.

The present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view of a heat-sensitive recording medium according to a preferred embodiment of the present invention. As shown in the figure, this thermal recording medium has a structure in which a substrate 1, a coloring layer 2, a thermal sensitizing layer 3, a metal thin film layer 4 and a protective layer 5 are sequentially laminated.

The base material 1 used in the present invention may be the same as the base material conventionally used as a base material of a thermal recording medium, and has mechanical toughness, flexibility, heat resistance and the like. Can be selected as appropriate. Specific examples of such a base material include plastic films such as polyethylene terephthalate, polycarbonate and polyvinyl chloride, papers such as art paper and coated paper, metal plates and glass plates.

The thickness of the substrate 1 is not particularly limited, but is generally 50 to 1000 μm, preferably 50 to 400 μm.
m.

In the present invention, the colored layer 2 is visually observed when the metal thin film layer 4 is destroyed and thereby forms an image pattern in contrast with the remaining metal thin film layer 4. The coloring layer 2 is formed of a black paint in which a black coloring material mixed with coloring agents of yellow, magenta and cyan pigments or dyes is dispersed in a resin binder.

In the present invention, the colorants for yellow, magenta and cyan are not particularly limited and can be appropriately selected from various colorants according to the desired degree of black. Further, the resin binder for forming the above black paint is not particularly limited, and known ones can be appropriately used as necessary.

Although the thickness of the colored layer 2 is not particularly limited, it is generally preferably 0.5 to 10 μm.

The colored layer 2 can be formed by various coating methods such as gravure coating, reverse roll coating, knife coating and blade coating, and printing methods such as gravure printing and screen printing.

The heat-sensitive sensitizing layer 3 comprises a coloring layer 2 and a metal thin film layer 4.
It is provided in order to improve the adhesiveness with and to facilitate the thermal destruction of the metal thin film layer 4. Such a heat sensitizing layer 3
As such, polyester resin, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral resin, acrylic resin, polyurethane resin, epoxy resin and the like can be used.

The thickness of the heat-sensitized layer 3 is not particularly limited, but generally 0.5 to 5 μm is preferable.

A plasticizer and a cross-linking agent may be appropriately added to the heat-sensitive sensitizing layer 3.

When the metal thin film layer 4 is selectively heated according to image information, the heated portion shrinks and breaks, the hiding property of the broken portion is lost, and the colored layer 2 as the lower layer can be visually observed. It is a layer to do. As a result, the lower colored layer 2
And the remaining metal thin film layer 4 form an image pattern.
As such a metal thin film layer, tin, tellurium, indium, aluminum, bismuth, zinc, lead, gold, or any alloy thereof can be used, but tin having a low melting point or an alloy thereof is preferably used. You can

The thickness of the metal thin film layer 4 is not particularly limited, but if it is too thin, it will lack the concealing property, and if it is too thick, it will be less likely to be destroyed by heat. Therefore, the thickness is generally 500 to 5000 angstroms, preferably 500 to 5000 angstroms. 1500 Angstroms is preferred.

The metal thin film layer 4 can be formed by a known method such as a vacuum vapor deposition method, a sputtering method, a plating method, a transfer method and a laminating method.

The protective layer 5 is a layer for preventing the metal thin film layer 4 from being directly contacted with other objects and damaged.
A light transmissive resin as conventionally used can be used. Examples of such resins include thermoplastic resins such as acrylic resins and epoxy resins, and those having a glass transition point of 70 ° C. or higher such as heat or ultraviolet curable resins.

Although the thickness of the protective layer 5 is not particularly limited, it is generally preferably 1 to 10 μm.

The protective layer 5 can be formed by various coating methods such as gravure coating, reverse roll coating, knife coating and blade coating, and printing methods such as gravure printing and screen printing.

A general pressure-sensitive adhesive layer may be provided on the surface of the base material 1 opposite to the colored layer 2, and in this case, it is preferable to cover the pressure-sensitive adhesive layer with release paper.

[0031]

In the heat-sensitive recording medium of the present invention, the black color in the colored layer is formed from the black paint in which the black colorant mixed with the colorant of the pigments or dyes of yellow, magenta and cyan is dispersed in the resin binder. It is possible to prevent the thin film layer from being corroded, and it is possible to improve the storability of the image.

[0032]

EXAMPLES The present invention will be specifically described below with reference to examples.

Example 1 A milk-white polyethylene terephthalate film (manufactured by Diafoil Co., Ltd.) having a thickness of 188 μm was coated with a colored coating composition having the following composition by a gravure method so that the dry thickness would be 3 μm, and then at 110 ° C. It was dried to form a colored layer.

Colored paint Component name Amount (parts by weight) Polymethylmethacrylate resin-based anthraquinone dye Yellow ink (manufactured by Toyo Ink Mfg. Co., Ltd.) 30 Magenta ink (manufactured by Toyo Ink Mfg. Co., Ltd.) 30 Cyan ink (Toyo Ink Mfg. Co., Ltd.) 30 vinyl chloride-vinyl acetate copolymer (20% lacquer) 30 (manufactured by Union Carbide Co., Ltd.) fine silica powder (manufactured by Nippon Aerosil Co., Ltd.) 2 isocyanate curing agent (manufactured by Nippon Polyurethane Co., Ltd.) 5 toluene / MEK / IPA (15/10/5) 30 The following composition for thermal sensitizer was further coated on the colored layer in a thickness of 1.5 μm by a gravure method, and heat-sensitive by aging at 60 ° C. for 48 hours. A sensitizing layer was formed.

Composition for thermal sensitizer Component name Amount used (parts by weight) Acrylic-cellulose resin (30% lacquer) 100 (manufactured by Dainichiseika Co., Ltd.) Vinyl chloride-vinyl acetate copolymer (20% lacquer) 30 Fine particle silica powder (manufactured by Nippon Aerosil Co., Ltd.) 2 Isocyanate curing agent (manufactured by Nippon Polyurethane Co., Ltd.) 5 Toluene / MEK / Butanol (30/30/10) 70 Next, on the heat-sensitized layer, a vacuum deposition method is used. 1000 for tin
A metal thin film layer was formed by vapor deposition to a thickness of angstrom. At this time, tin was vapor-deposited so that the surface resistivity of tin was 1 Ω / □.

On the metal thin film layer, the following composition for forming a protective layer was applied in a thickness of 1.5 μm and dried at 110 ° C. to form a protective layer, whereby the thermal recording medium of the present invention was produced.

Protective Layer Forming Composition Component Name Amount Used (parts by Weight) Silicon Acrylic Resin (44% Solid Content) 100 (Dainippon Ink and Chemicals, Inc.) Epoxy Curing Agent (80% Solid Content) 20 (Dainippon) Ink Chemical Co., Ltd.) Low molecular weight polyethylene wax dispersion (15% solid content) 20 (BASF Co., Ltd.) Talc (Fuji Talc Co., Ltd.) 10 Alumina (Sumitomo Chemical Co., Ltd.) 5 Toluene / MEK / IPA ( 40/40/20) 100 The resulting thermosensitive recording medium was immersed in 5% saline for 24 hours,
The degree of corrosion of the metal thin film layer was visually evaluated. as a result,
No change was observed in the metal thin film layer, indicating that the metal thin film layer had excellent storage stability.

Comparative Example 1 A thermosensitive recording medium was produced in the same manner as in Example 1 except that the coloring paint having the following composition was used.

Coloring paint Component name Amount used (parts by weight) Black ink containing urethane resin carbon black 100 (Toyo Ink Mfg. Co., Ltd.) Vinyl chloride-vinyl acetate copolymer (20% lacquer) 30 (Union Carbide Co., Ltd.) ) Fine particle silica powder (manufactured by Nippon Aerosil Co., Ltd.) 2 Isocyanate-based curing agent (manufactured by Nippon Polyurethane Co., Ltd.) 5 Toluene / MEK / IPA (15/10/5) 30 About the obtained thermosensitive recording medium, the same as in Example 1 When a corrosion resistance test was performed, it was observed that the metal thin film layer was corroded in black.

[0040]

The heat-sensitive recording medium of the present invention can form a highly storable image without corroding the metal thin film layer even when the black colored layer is formed.

[Brief description of drawings]

FIG. 1 is a sectional view of a preferred embodiment of a thermal recording medium of the present invention.

[Explanation of symbols]

 1 Base Material 2 Colored Layer 3 Thermal Sensitization Layer 4 Metal Thin Film Layer 5 Protective Layer

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Masao Kuroiwa 1-5-1 Taito, Taito-ku, Tokyo Toppan Printing Co., Ltd.

Claims (1)

[Claims] 1. A thermal recording medium comprising a base material, a coloring layer, a heat-sensitizing layer, a metal thin film layer and a protective layer, which are laminated in this order, and the coloring layer is a black colorant containing a mixture of yellow, magenta and cyan colorants. A heat-sensitive recording medium containing: