JPH047192A - Thermal recording medium - Google Patents

Abstract

PURPOSE:To enhance heat resistance, lightfastness, chemical resistance, abrasion resistance and the matching properties with a thermal head by using a support and the color layer, metal membrane layer and protective layer successively provided to the single surface of the support toward the outside direction as essential constitutional elements and adding an acrylic resin, a lubricant and heat-resistant pigment to the protective layer. CONSTITUTION:A thermal recording medium is constituted of a combination of a support 1, a color layer 2, a metal membrane layer 3, a protective layer 4, an under layer 5 and adhesive layers 6, 7. As essential constitutional elements, the color layer 2, the metal membrane layer 3 and the protective layer 4 are successively laminated on one surface of the support 1, and the protective layer 4 contains at least three components of an acrylic resin, a lubricant and heat- resistant pigment. The acrylic resin used in the protective layer pref. has Tg of 30 deg.C or higher. As the lubricant, a material such as polyethylene wax, a metal salt of higher fatty acid or higher fatty acid amide is designated and the heat-resistant pigment is mainly selected from inorg. pigments such as silica, talc and the like.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is used for recording the output of electronic computers, facsimile machines, tickets, labels, cards, etc. It is related to recording media.

[Prior Art] [Problem to be Solved by the Invention] The thermal recording method, which obtains images by utilizing physical or chemical changes in substances caused by thermal energy, does not generate noise during recording and requires development and fixing. Because of its advantages such as not being able to copy documents, it is expected to be used not only for copying documents, but also for recording computer output, facsimile reception records, and printing on tickets, labels, and cards. Many types of recording materials for this thermal recording method have been proposed to date, but among them, recording materials that use leuco bodies such as fluoran dyes as coloring agents are widely used because of their excellent thermal sensitivity. It is used in the area. However, thermophilic recording paper that uses leuco bodies as a coloring agent has many drawbacks, such as being easily colored by pressure or organic solvents such as alcohol, and also having poor light resistance, heat resistance, and water resistance. It is something.

To solve these drawbacks, heat-sensitive recording media using a metal thin film layer as a heat-sensitive layer have been developed. This method uses a heat source such as a thermal head, laser light, or flash light to destroy the metal thin film layer in the form of an image, thereby lifting the colored layer provided under the metal thin film layer and forming an image. . Therefore, unlike the leuco type, this method uses a metal thin film layer and therefore has essentially excellent heat resistance and light resistance.

However, this heat-sensitive recording medium having a metal thin film layer requires significantly greater thermal energy during recording than a normal leuco-based recording medium, so head matching becomes a problem when a thermal head is used. In other words, the surface of the thermosensitive recording medium cannot withstand the high heat of the thermal head, causing sticking and adhesion of residue, making practical continuous recording impossible.

[Means for Solving the Problems] [Operation] The object of the present invention is to provide a thermal recording medium having a metal thin film layer that solves the above-mentioned drawbacks, which has good heat resistance, light resistance, chemical resistance, abrasion resistance, and a thermal head. The objective is to provide products with excellent matching properties.

In other words, the essential components are a support, a colored layer provided outwardly on one side of the support, a metal thin film layer, and a protective layer, and an under layer between the support and the colored layer, the colored layer and the metal. The adhesion between the thin film layers <1> and the adhesive layer (II) between the metal thin film layer and the protective layer are optional components, and the protective layer contains at least an acrylic resin, a lubricant, and a heat-resistant pigment. This is a characteristic heat-sensitive recording medium.

The present invention will be explained below with reference to the drawings.

The heat-sensitive recording medium of the present invention is composed of a combination of support #1, colored layer 2, metal thin film layer 3, protective layer 4, under layer 5, adhesive layer (I) 6, and adhesive layer (■) 7, Examples of layer configurations are shown in FIGS. 1-5.

That is, FIG. 1 shows a basic configuration consisting only of essential components constituting the heat-sensitive 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. be. Further, in FIG. 2, in addition to the basic components shown in FIG. 1, an optional component adhesive layer (I) 6 is added to the colored layer 2.
and a metal thin film layer 3. In addition to the basic configuration shown in FIG. 1, FIG.
It consists of a configuration provided between. Also, the fourth
The figure shows a configuration in which, in addition to the basic configuration of FIG. 1, optional constituent elements, an adhesive layer (1) and an adhesive layer (II), are provided. 5 shows a structure in which, in addition to the structure shown in FIG. 4, an optional underlayer 5 is provided between the support 1 and the colored layer 2.

Each of the above layers will be specifically explained.

Examples of the support 1 include mechanically strong and flexible plastics such as polyethylene terephthalate film, coated paper, art paper, laminated paper, glass, and metal.

The colored layer 2 is a layer that appears as an image by image-wise heating, and is made of cellulose derivatives such as ethyl cellulose, hydroxyethyl cellulose, cellulose acetate propionate, and cellulose acetate, styrene resins such as polystyrene, poly-α-methylstyrene, or styrene copolymer. Polymer resins, single or copolymer resins of acrylic resins or methacrylic resins such as polymethyl methacrylate, polyethyl methacrylate, polyethyl acrylate, and polybutyl acrylate, rosin, rosin-modified phenolic resin, rosin-modified maleic acid resin, polymerization Various pigments or dyes are added to binders such as rosin ester resins such as rosin, polyvinyl acetate resins, coumaron resins, vinyl toluene resins, vinyl chloride resins, polyester resins, polyurethane resins, butyral resins, etc., depending on the color to be colored. If necessary, plasticizers, stabilizers, waxes, hardeners, and dispersants are added, and then a colored paint or ink is prepared by sufficiently kneading with a solvent or diluent. It can be formed in a desired area by a coating method such as a coating method, a roll method, a knife edge method, an offset method, or a printing method.

The metal thin film layer 3 is made of Te, Sn, Aj! , old, Pb,
A metal such as Zn, an alloy thereof, or a compound of the above metals such as Te/carbide can be formed on the colored layer 2 provided on the support 1 by a vacuum evaporation method, a sputtering method, a plating method, etc. . This layer preferably has a low melting point since it plays a role as a heat-sensitive recording layer. Further, the thickness of this layer is about 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 from sticking and residue when recording with a thermal head.

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

The acrylic resin used for the protective layer 4 includes methacrylic acid, acrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, and styrene. It is obtained by monopolymerizing or copolymerizing monomers such as. In consideration of wear resistance, the acrylic resin preferably has a Tg of 30 degrees or more.

As lubricants, waxes such as polyethylene wax, paraffin wax, microcrystalline wax, etc.
Materials include higher fatty acid metal salts such as zinc stearate and calcium stearate, higher fatty acid amides such as stearic acid amide and hehenic acid amide, silicone oil, fine Teflon powder, and fine boron nitride powder. The heat-resistant pigment is mainly selected from inorganic pigments such as silica, calcium carbonate, aluminum hydroxide, magnesium hydroxide, zeolite, and clay talc.

In addition, the above acrylic resin, lubricant,
Preferable content ratios of the heat-resistant pigment are 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 adhesion between the two, and does not require any special restrictions and can be selected from many conventionally known polymers. It is. For example, examples of solvent-soluble polymers include polyester, polyurethane, and acrylic resin, and examples of water-soluble polymers include polyvinyl alcohol, starch, and various emulsion resins.

The adhesive layer (I) 6 is located between the colored layer 2 and the metal thin film layer 3 and improves the adhesion between them. Further, during thermal recording, a polymer having appropriate thermoplasticity is used in order to promote the destruction of the metal thin film layer 3 and improve the thermal recording sensitivity. Specifically, polystyrene,
Examples include acrylic resins such as polymethyl methacrylate, cellulose resins such as cellulose acetate propionate, vinyl chloride-vinyl acetate copolymers, polyester resins, polyurethane resins, and epoxy resins. It is also possible to add thermofusible substances such as plasticizers and waxes to control thermoplasticity.

Further, a curing agent may be used in the adhesive layer (I) in order to impart a certain level of solvent resistance to facilitate lamination of the next layer.

The adhesive layer (■) 7 is located between the metal thin film layer 3 and the protective layer 4 to improve the adhesion between them, and works to physically and chemically protect the metal thin film layer 3 together with the protective layer 4. is also required. In consideration of chemical resistance, suitable resins include polyester resins, polyurethane resins, acrylic resins, vinyl chloride-vinyl acetate copolymers, epoxy resins, and cellulose resins.

Furthermore, in the heat-sensitive recording medium of the present invention, various pigments and additives may be used in each layer except the above-mentioned metal thin film layer, if necessary. In particular, in at least one of the under layer 5, the colored layer 2, and the adhesive layer (I) 6, inorganic white pigments such as silica, calcium carbonate, aluminum hydroxide, clay, and talc, crosslinked polystyrene, and polyethylene beads are added. , organic transparent or white pigments such as silicone beads, coloring pigments such as red lead, ultramarine blue, titanium yellow, red yellow lead, and plastic type fluorescent pigments.

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

(Example) Examples will be described below.

Example 1 A heat-sensitive recording medium of the present invention was obtained by sequentially laminating the following layers on a milky white polyethylene terephthalate film having a thickness of 188 μm by coating or the like.

(1) The composition of the two sides of the colored layer is dried at a temperature of 110°C.
It was applied in an amount of 3.2 g/I.

The coating was carried out at a temperature of 2.3 s/m at a coating rate of 2.3 s/m.

100 g of polymethyl methacrylatene solution 1 g of calcium carbonate toluene 0 g Metal thin film layer: Tin was deposited by vacuum evaporation to a thickness of 600 when measured using a crystal oscillator method.

A heat-sensitive recording medium of the present invention was obtained by sequentially laminating the following layers on a milky white polyethylene terephthalate film having a drying temperature of 110 g μm and a drying temperature of 18 g μm on the two sides of the protective layer.

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

(2) Adhesive layer (I): The following composition was dried at a temperature of 11
Coating was carried out at 0° C. at a coating weight of 1.8 g/m 2 .

L toluene 60g (5) The composition below the two sides of the protective layer was dried at a temperature of 110°C, with a coating amount of 2.
．． It was applied at 1 g/m.

Limethyl methacrylate solution 100g (manufactured by Soken Kagaku Co., Ltd.: Thermolac M-2000 solid content 10%) Metal thin film layer: Adhesive layer (II) When indium was measured by the vacuum evaporation method using the standard film thickness side method using the quartz crystal method. The total number of people was evaporated to 500.

Dry salt with a composition of less than 2 degree 110℃, coating amount 1.3g/n? It was coated with

Example 3 The following layers were sequentially laminated by coating or the like on a milky white polyethylene terephthalate film having a thickness of 188 μm to obtain a heat-sensitive 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 (■): The following composition is dried at a temperature of 11
Coating was carried out at 0° C. at a coating weight of 1.8 g/m 2 .

Comparative Example 1 A comparative heat-sensitive recording medium was prepared in the same manner as in Example 3 except that aluminum hydroxide in the protective layer was removed.

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

(4) Adhesive layer (■): Adhesive layer (I
I) was established.

(5) Protective layer: one with the following composition, dried at 110℃,
The coating amount was 1.8 g/rrl.

[Toluene 0 g Comparative Example 2 A comparative heat-sensitive recording medium was prepared in the same manner as in Example 3 except that the fluorocarbon dispersion in the protective layer was removed.

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

The following characteristics were evaluated for the heat-sensitive recording medium produced above.

(1) Recording Characteristics Image recording was performed using a thermal head with a pulse width of 2.5 ms and applied energy of 0.6 W.

Recorded density and background density were measured using Macbeth Densitometer RD-914 (
(visual filter).

(2) Hendomanoting property 10,000 continuous pulses were printed under the above recording conditions to examine stick and debris adhesion.

(3) Light resistance After exposure for 6 hours using a fade meter, the density of the recorded area and the background was similarly measured using a Macbeth densitometer.

(4) Water resistance It was immersed in water at 20°C for 3 days to examine its water resistance.

(5) Alcohol resistance A 50% aqueous solution of ethanol was added dropwise and 2 minutes later, it was wiped off 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 100 g load of plastic eraser (Tombo Mono) was placed on it, and the plasticizer resistance was examined by leaving it at 20°C for 24 hours.

(8) Heat resistance It was placed in a dryer at 100°C for 10 minutes and tested for heat resistance 8 times.

(9) Wear resistance The wear resistance was examined by passing through an automatic ticket gate 2000 times in the same direction.

The above evaluation results are shown in Table 1 in three grades: ○△x.

Table [Effects of the Invention] Since the present invention is made of the above-described structure and materials, the thermal recording material has excellent heat resistance, light resistance, water resistance, chemical resistance, abrasion resistance, etc., and also has excellent head matching properties. media can be provided.

[Brief explanation of drawings]

1 to 5 are all cross-sectional views showing the layer structure of the heat-sensitive recording medium obtained by the present invention. 1: Support, 2: Colored layer, 3: Metal thin film layer, 4: Protective layer, 5: Under layer, 6: Adhesive layer (1), 7: Adhesive layer (I
t) As is clear from Table 1, the heat-sensitive recording medium of the present invention maintains good recording properties while meeting the practical properties necessary for heat-sensitive recording media, such as head matching properties, which are indicators of sticking and residue adhesion, and light resistance. Everything was equally satisfying.

Claims (1)

[Claims] The essential components include a support, a colored layer, a metal thin film layer, and a protective layer provided sequentially outward on one side of the support, an under layer between the support and the colored layer, a colored layer, and a metal thin film layer. An adhesive layer (I) between the metal thin film layer and the protective layer (II) is an optional component, and the protective layer contains at least an acrylic resin, a lubricant, and a heat-resistant pigment. A heat-sensitive recording medium characterized by: