JP2587709B2 - Thermal recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is used for output records, facsimile, tickets, labels, cards, etc. of electronic computers, and is recorded by utilizing physical changes due to heating. It relates to a recording medium.

[Prior art] [Problems to be solved by the invention] A thermal recording method in which an image is obtained by using a physical or chemical change of a substance due to thermal energy does not generate noise at the time of recording and requires development and fixing. It is expected to be used not only for copying documents and the like, but also for output records of electronic computers, facsimile reception records, and print records on tickets, labels, cards, etc., based on the advantages such as not being used. Many types of recording materials have been proposed as recording materials for the thermal recording method, but recording materials using a leuco body such as a fluoran dye as a coloring agent have excellent thermal sensitivity. Used in many directions. However, heat-sensitive recording paper using leuco as a coloring agent has many drawbacks, such as being easily colored by pressure or an organic solvent such as alcohol, and having poor light resistance, heat resistance, and water resistance. It is.

As a solution to such a drawback, a heat-sensitive recording medium using a metal thin film layer as a heat-sensitive layer has been developed. In this method, an image is formed by breaking a metal thin film layer into an image by a heat source such as a thermal head, laser light, or flash light, so that a colored layer provided below the metal thin film layer is raised. . Therefore, unlike the leuco method, this method uses a metal thin film layer, so it is essentially heat resistant,
Excellent light fastness.

However, a thermal recording medium having this metal thin film layer requires considerably more heat energy for recording than a normal leuco-based recording medium. Therefore, when a thermal head is used, head matching becomes a problem. That is, the surface of the thermal recording medium cannot withstand the high heat of the thermal head,
Sticking or scum sticking occurs, making practical continuous recording impossible.

[Means for Solving the Problems] [Action] The object of the present invention is to provide a heat-sensitive recording medium having a metal thin-film layer that has solved the above-mentioned disadvantages, heat resistance, light resistance, chemical resistance,
It is an object of the present invention to provide a material excellent in wear resistance and matching property with a thermal head.

That is, a support, a coloring layer sequentially provided on one side in an outward direction, a metal thin film layer, and a protective layer are essential components, and an under layer between the support and the coloring layer, a coloring layer and a metal. Adhesion between the thin film layers (I) and adhesion layer between the metal thin film layer and the protective layer (II) are optional components, and the protective layer contains at least an acrylic resin, a wax and a heat-resistant pigment. This is a thermosensitive recording medium that is characterized.

 Hereinafter, the present invention will be described with reference to the drawings.

The thermosensitive recording medium of the present invention comprises a support 1, a colored layer 2, a metal thin film layer 3, a protective layer 4, an under layer 5, an adhesive layer (I) 6,
It is composed of a combination of adhesive layers (II) 7, and examples of the layer structure are shown in FIGS.

That is, FIG. 1 shows a basic structure consisting of only essential components constituting the thermosensitive recording medium of the present invention, in which a colored layer 2, a metal thin film layer 3 and a protective layer 4 are sequentially laminated on one side of a support 1. is there. FIG. 2 shows a structure in which an adhesive layer (I) 6, which is an optional component, is provided between the colored layer 2 and the metal thin film layer 3 in addition to the basic components shown in FIG. FIG. 3 shows a configuration in which an adhesive layer (II) 7, which is an optional component, is provided between the metal thin film layer 3 and the protective layer 4 in addition to the basic configuration of FIG. FIG. 4 shows a configuration in which an adhesive layer (I) and an adhesive layer (II), which are optional components, are provided in addition to the basic configuration of FIG. FIG. 5 shows a configuration in which an under layer 5 as an optional component is provided between the support 1 and the colored layer 2 in addition to the configuration of FIG.

 Each of the above layers will be specifically described.

Examples of the support 1 include a mechanically tough and flexible polyethylene terephthalate film and its resistant plastic, coated paper, art paper, laminated paper, glass, metal, and the like.

The coloring layer 2 is a layer which appears as an image by imagewise heating, and includes cellulose derivatives such as ethyl cellulose, hydroxyethyl cellulose, cellulose acetate propionate, and cellulose acetate, polystyrene, and poly-α-.
Styrene resin such as methyl styrene or styrene copolymer resin, acrylic or methacrylic resin such as polymethyl methacrylate, polyethyl methacrylate, polyethyl acrylate, polybutyl acrylate or copolymer resin, rosin, rosin-modified phenol Resin, rosin modified maleic resin, rosin ester resin such as polymerized rosin, polyvinyl acetate resin, coumarone resin, vinyl toluene resin, vinyl chloride resin, polyester resin, polyurethane resin, butyral resin, etc. After adding various pigments or dyes as needed, further adding a plasticizer, a stabilizer, a wax, a curing agent, and a dispersant, and then kneading the mixture with a solvent or a diluent. Using the usual gravure method, roll method, Ifueddji method, a coating method or a printing method such as offset method, can be formed in a desired portion.

The metal thin film layer 3 is made of a support such as a metal such as Te, Sn, Al, Bi, Pb, and Zn, or an alloy of these metals or a compound of the above-mentioned metal such as Te / carbide, by a vacuum deposition method, a sputtering method, a plating method, or the like. 1 can be formed on the colored layer 2 provided on the substrate 1. This layer preferably has a low melting point because it functions as a heat-sensitive recording layer. The thickness of this layer is 100 to 1 μm, preferably about 300 to 600 °.

In addition to physically and chemically protecting the metal thin film layer, the protective layer 4 is required to be free of sticking and residue when recording with a thermal head.

The main feature of the present invention is that the constituent material of the protective layer 4 contains at least three components of an acrylic resin, a wax and a heat-resistant pigment.

The acrylic resin used for the protective layer 4 is methacrylic acid, allylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, styrene These are obtained by homo- or copolymerization of such monomers. In consideration of abrasion resistance here, the acrylic resin preferably has a Tg of 30 degrees or more.

Examples of the wax include polyethylene wax, paraffin wax, and microcrystalline wax. The heat-resistant pigment is mainly selected from inorganic pigments such as silica, calcium carbonate, aluminum hydroxide, magnesium hydroxide, zeolite, clay, and talc.

The preferred content of the above-mentioned acrylic resin, wax and heat-resistant pigment in the protective layer is 60 to 95% by weight, 2 to 25% by weight, and 2 to 40% by weight, respectively.

Next, the under layer 5 is provided between the support 1 and the colored layer 2 to improve the adhesion between them, and does not require any special restriction, and can be selected from many conventionally known polymers. It is. For example, polyester, polyurethane, and acrylic resin are used as the solvent-soluble polymer, and polyvinyl alcohol, starch, and various emulsion resins are used as the water-soluble polymer.

The adhesive layer (I) 6 is provided between the colored layer 2 and the metal thin film layer 3 to improve the adhesive strength between them. Further, at the time of thermal recording, a polymer having an appropriate thermoplasticity is used in order to promote the destruction of the metal thin film layer 3 and also to enhance the thermal recording sensitivity. Specific examples include acrylic resins such as polystyrene and polymethyl methacrylate, cellulose resins such as cellulose acetate propionate, vinyl chloride-vinyl acetate copolymer, polyester resins, polyurethane resins, and epoxy resins.
In order to control thermoplasticity, it is also possible to add a heat-fusible substance such as a plasticizer or wax. Adhesive layer (I)
A curing agent can also be used for No. 6 in order to have a certain solvent resistance and to facilitate lamination of the next layer.

The adhesive layer (II) 7 is provided between the metal thin film layer 3 and the protective layer 4 to improve the adhesive strength between them, and the protective layer 4
At the same time, it is also required to have a function of physically and chemically protecting the metal thin film layer 3. In consideration of chemical resistance, suitable resins include polyester resin, polyurethane resin, acrylic resin, vinyl chloride-vinyl acetate copolymer, epoxy resin, and cellulose resin.

Further, in the heat-sensitive recording medium of the present invention, various pigments and additives can be used for each layer except the above-mentioned metal thin film layer as needed. In particular, at least one of the under layer 5, the colored layer 2, and the adhesive layer (I) 6 includes silica,
Inorganic white pigments such as calcium carbonate, aluminum hydroxide, clay, and talc; organic transparent or white pigments such as cross-linked polystyrene, polyethylene beads, and silicone beads; lead red, ultramarine, titanium yellow, and reddish graphite;
A coloring pigment such as a plastic type fluorescent pigment can be blended.

In the practice of the present invention, a label may be provided by providing a magnetic recording layer on the back surface of the support or by providing an adhesive layer and a separator. It is also possible to print on the protective layer.

(Example) An example is described below.

Example 1 The following layers were successively laminated on a milky white polyethylene terephthalate film having a thickness of 188 μm by coating or the like to obtain a thermosensitive recording medium of the present invention.

(1) Colored layer: The following composition having a drying temperature of 110 ° C.
The coating amount was 3.2 g / m ² .

(2) Metal thin film layer: Tin was vapor-deposited by a vacuum vapor deposition method so as to have a thickness of 600 ° when measured by a film thickness measurement method using a quartz oscillator method.

(3) Protective layer: A protective layer having the following composition was applied at a drying temperature of 110 ° C. and a coating amount of 2.3 s / m ² .

Example 2 The following layers were sequentially laminated on a milky white polyethylene terephthalate film having a thickness of 188 μm by coating or the like to obtain a thermosensitive recording medium of the present invention.

(1) Colored layer: A colored layer was provided in the same manner as in Example 1.

(2) Adhesive part (I): The following composition having a drying temperature of 110
The coating was performed at a temperature of 180 ° C. and a coating amount of 1.8 g / m ² .

(3) Metal thin film layer: Indium was vapor-deposited by a vacuum vapor deposition method so as to have a thickness of 500 ° when measured by a film thickness measurement method by a quartz oscillator method.

(4) Adhesive layer (II): The following composition having a drying temperature of 110
The coating was performed at 1.3 ° C. and a coating amount of 1.3 g / m ² .

(5) Protective layer: The protective layer having the following composition was applied at a drying temperature of 110 ° C. and a coating amount of 2.1 g / m ² .

Example 3 The following layers were sequentially laminated on a milky white polyethylene terephthalate film having a thickness of 188 μm by coating or the like to obtain a thermosensitive recording medium of the present invention.

(1) Colored layer: A colored layer was provided in the same manner as in Example 1.

(2) Adhesive layer (I): The following composition having a drying temperature of 110
The coating was performed at a temperature of 180 ° C. and a coating amount of 1.8 g / m ² .

(3) Metal thin film layer: A tin vapor deposition layer was provided in the same manner as in Example 1.

(4) Adhesive layer (II): The adhesive layer (I
I).

(5) Protective layer: A protective layer having the following composition was applied at a drying temperature of 110 ° C. and an application amount of 1.8 g / m ² .

Comparative Example 1 A comparative thermosensitive recording medium was produced in the same manner as in Example 3 except that aluminum hydroxide in the protective layer was omitted.

Comparative Example 2 A comparative thermosensitive recording medium was prepared in the same manner as in Example 3 except that the oxidized microwax in the protective layer was omitted.

Comparative Example 3 A comparative thermosensitive recording medium was prepared in the same manner as in Example 3 except that the acrylic resin in the protective layer was changed to a linear saturated polyester resin (manufactured by Toyobo Co., Ltd .: Byron 200).

The following characteristics were evaluated for the thermosensitive recording medium manufactured as described above.

(1) Recording characteristics Pulse width 2.5ms, applied energy 0.6 by thermal head
Image recording was performed with W. The recording density and the background density were measured using a Macbeth densitometer RD-914 (visual filter).

(2) Head Matching Property Continuous printing of 10,000 pulses was performed under the above recording conditions, and the state of sticking and residue was examined.

(3) Lightfastness After exposure for 6 hours with a fade meter, the density of the recorded portion and the background was measured in the same manner using a Macbeth densitometer.

(4) Water resistance Water resistance was examined by immersing in water at 20 ° C. for 3 days.

(5) Alcohol resistance A 50% aqueous solution of ethanol was dropped and wiped off 2 minutes later to examine the alcohol resistance.

(6) Oil resistance Cottonseed oil was applied and left at 20 ° C. for 24 hours to examine oil resistance.

(7) Plasticizer resistance A plastic eraser (dragonfly) was applied with a load of 100 g and left at 20 ° C for 24 hours to examine the plasticizer resistance.

(8) Heat resistance The sample was placed in a dryer at 100 ° C. for 10 minutes, and the heat resistance was examined.

(9) Abrasion resistance Abrasion resistance was examined by passing the gate of an automatic ticket gate 2000 times in the same direction.

 The above evaluation results are shown in Table 1 in three stages of △ ××.

As is clear from Table 1, the thermosensitive recording medium of the present invention maintains all the practical characteristics required for the thermosensitive recording medium, such as head matching property and light resistance, which are guidelines for sticking and sticking, while maintaining good recording properties. Was satisfied.

〔The invention's effect〕

Since the present invention is composed of the above configuration and material, it is possible to provide a heat-sensitive recording medium having excellent heat resistance, light resistance, water resistance, chemical resistance, abrasion resistance, etc., and excellent head matching properties. .

[Brief description of the drawings]

1 to 5 are cross-sectional views showing the layer structure of the thermosensitive recording medium obtained by the present invention. 1: support, 2: colored layer, 3: metal thin film layer, 4: protective layer, 5: underlayer, 6: adhesive layer (I), 7: adhesive layer (II)

Continuation of the front page (72) Inventor Kensaku Higashi 3-1 Yosoba Town, Shizuoka City, Shizuoka Pref. 63-144086 (JP, A) JP-A-1-128873 (JP, A)

Claims (1)

(57) [Claims] 1. An under layer between a support and a colored layer, comprising a support, a coloring layer sequentially provided outward on one side thereof, a metal thin film layer, and a protective layer as essential components. The adhesive layer (I) between the coloring layer and the metal thin film layer and the adhesive layer (II) between the metal thin film layer and the protective layer are optional components, and the protective layer is made of an acrylic resin, wax and heat-resistant material. A heat-sensitive recording medium containing at least a pigment.