JPH0548199B2 - - Google Patents

Description

[Detailed description of the invention]

Purpose of invention

[Industrial application field]

The present invention relates to a heat-sensitive recording sheet used for heat-sensitive recording using a thermal head. The heat-sensitive recording sheet of the present invention is useful for printing, for example, train tickets, especially commuter passes.

[Conventional technology]

The thermal recording method is widely used because it is noiseless, odorless, has a simple recording device, consumes little energy, and is maintenance-free. Conventionally, many of the heat-sensitive recording papers used are of the leuco type, in which a heat-sensitive layer is formed using a thermoplastic resin binder made of a leuco dye and a color developer. However, this type of recording paper has the disadvantage that recorded images cannot be fixed and storage stability is poor. Various fixable thermal recording papers using diazonium salts and coupling agents have been developed, but these thermal papers are limited to special papers as supports and are expensive. Another disadvantage is that it is difficult to print or process. Another thermal recording method that solves these drawbacks is a thermal transfer method. The advantage of this method is that the material of the support does not need to be selected. However, the recording apparatus requires a paper feeding mechanism and a transfer ribbon feeding mechanism, making it large-scale. In addition, since the recording part of a thermal transfer device generally consists of a thermal head and one roller for pressing and feeding, slips may occur between the paper and the ribbon.
There are problems such as background stains and misalignment of recorded images.

[Problems to be solved by the invention]

An object of the present invention is to provide a heat-sensitive recording sheet which can theoretically solve the problem of slippage in the heat-sensitive recording area, which is a problem with such heat-sensitive transfer methods, and which does not cause image misalignment or scumming. . Composition of the invention

[Means to solve the problem]

As shown in FIG. 1, the heat-sensitive recording sheet of the present invention is provided with an ink adhesion adjusting layer on the surface of the support, which increases or decreases the adhesion of ink by heating, and an ink layer and a protective layer on the ink adhesion adjusting layer. If the ink adhesion adjusting layer increases the ink adhesion by heating, the adhesion of the ink layer to the support after heating is different from that of the ink layer. If the ink adhesion adjusting layer is one that reduces the ink adhesion by heating, the adhesion of the ink layer to the support after heating is greater than the adhesion of the ink layer to the support layer. The adhesion force between each layer is selected so that the adhesion force between the ink layer and the protective layer is smaller than the adhesion force between the ink layer and the protective layer. Either the non-printing part of the ink layer remains on the support and the non-printing area is removed together with the protective layer, resulting in positive printing, or the non-printing area of the ink layer remains on the support and the printing area is removed together with the protective layer, resulting in negative printing. It is characterized by being configured so that it can be carried out. In the embodiment shown in FIG. 2, the adhesion of the ink layer to the support and the adhesion to the protective layer are balanced so that the latter is greater when no heating is performed. When heated with a thermal head, the adhesive force of the printed part 4A of the ink layer 4 to the support 2 increases and exceeds the adhesive force to the protective layer, so by peeling off the protective layer, the printed part 4A increases. Only a small amount of ink remains, and positive printing is performed. In the embodiment of FIG. 3, the balance of the adhesion of the ink layer is reversed to the above, so that the adhesion to the support is greater than the adhesion to the protective layer. When heated by the thermal head, the printed portion 4 of the ink layer 4
The adhesion force of A to the support decreases and becomes lower than the adhesion force to the protective layer, so by peeling off the protective layer, only the ink is removed from the printed area and negative printing is performed. That's why.

[Embodiment]

Supports include medium quality paper, high quality paper, art paper,
Common papers such as coated paper, Kent paper, paperboard, and imitation art paper, and plastic films such as polyethylene, polystyrene, polyvinyl chloride, polypropylene, acrylic, polyester, and polycarbonate are used. Their thickness, basis weight, etc. may be determined as appropriate depending on the application. When using paper or a porous or matte-finished plastic film, it is preferable to coat it with a filler such as a resin to smooth the surface when providing the ink adhesion adjusting layer. The material forming the ink adhesion adjustment layer is selected from different groups depending on whether the printing to be performed is positive or negative. When producing thermal recording paper that performs positive printing, heating increases the adhesion with the ink layer.
Use natural or synthetic waxes. When performing negative printing, choose a water- or alcohol-soluble resin whose adhesive strength with the ink layer decreases when heated. To give you an example of these,
Natural resins such as gelatin, casein, and shellac, polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl butyral, polyvinyl acetal, polyacrylates such as sodium polyacrylate, cellulose acetate butyrate, cellulose acetate propionate, hydroxypropyl cellulose, etc. These are alcohol-soluble cellulose, styrene-maleic acid copolymer, and isobutylene-maleic acid copolymer. Of course, two or more of these may be used in combination. To form the ink layer, a material that melts when heated is used. Those having a melting point of 50 to 150°C and having no adhesive properties are preferable. As such materials, synthetic or natural waxes and polymers such as low melting point paraffin wax, microcrystalline wax, and carnauba wax are used.
These materials are used as a binder, and colorants such as carbon black, various dyes, and pigments are blended to make ink. The resin forming the protective layer can be selected from a wide variety of resins, as described below. The vinyl resin group includes polyvinyl chloride, vinyl chloride-vinyl acetate copolymers, acid-modified vinyl acetate, partially saponified polyvinyl acetate, and the like. Representatives of the acrylic resin group are polymethyl methacrylate and polybutyl acrylate.
Including copolymers, acid-modified products, and thermally crosslinked products. Furthermore, polyamide resins, polyester resins, acid-modified products thereof, rubber resins, and photocurable resins into which photosensitive groups are introduced can also be used. Natural resins are also useful, and cellulosic resins such as cellulose acetate, casein, shellac, gelatin, and the like can be used. Other materials that can be used include polyurethane,
There are many types, including thermosetting urethane resins, thermosetting or alkyd-modified melamine resins, epoxy resins, polyimides, vinylidene resins, and polyether resins. A lubricant or a thermal release agent may be used in the protective layer to improve the slippage of the print head. The first group of lubricants or heat release agents include waxes such as polyethylene wax and paraffin wax, higher fatty acid amides, higher fatty acid esters, higher fatty acid salts, higher alcohols, and phosphoric acid esters such as lecithin. The second group includes powders such as fluorine resin, vinyl fluoride resin, and guanamine resin, boron titanide, silica, wood powder, and talc. The above-mentioned lubricant or thermal release agent may be used by being mixed into the protective layer material, or may be applied to the surface.

[Example 1] The following composition for a protective layer was prepared. (“Parts” are parts by weight. The same applies hereinafter) Vinylidene fluoride/ethylene tetrafluoride copolymer “Kynar 7201” (manufactured by Pennwalt)
...8 parts polyester polyol "Takeratsuku Melee"
534TV” (Takeda Pharmaceutical, 40% MEK solution)
…40 parts fluorocarbon “F-57” (manufactured by Axel)
...5 parts benzoguanamine resin powder "Epostor S"
(Nippon Shokubai Chemical) ...3 parts Lecithin (manufactured by Ajinomoto) ...1 part MEK ...35 parts Toluene ...45 parts Total 137 parts For the above composition, isocyanate "Coronate L" (manufactured by Nippon Polyurethane, 75% ethyl acetate solution) ), ink: isocyanate = 14:3
(weight ratio). Thicken this mixture
A protective layer was formed on one side of a 3μ polyethylene terephthalate film by gravure coating so that the film thickness after drying was 1μ. Separately, prepare a thermal transfer ink with the following composition, heat it to 100°C to melt it, and apply it to the other side of the film using the gravure reverse method to form a thick film.
Hot melt coated to a thickness of 3μ,
A heat-sensitive transfer ink layer was provided. Parafine wax…10 parts Carnauba wax…10 parts polybutene “VH-100” (manufactured by Nippon Oil Co., Ltd.)
…1 part carbon black “Seest S” (Tokai Electrode Co., Ltd.)
) ... 2 copies total 23 copies Imitation art paper "Tokukobishi N" (37 kg/46 manufactured by Mitsubishi Paper Mills) is hot-melt coated with beeswax heated to 120℃ and melted using the rod coating method. Then, an ink adhesion adjustment layer having a film thickness of 5 μm after cooling was provided. A film having a heat-sensitive transfer ink layer and art paper were laminated so that these layers were in contact with each other, and the layers were bonded under pressure by calendering to obtain a heat-sensitive transfer recording sheet. After thermal recording was performed on this thermal transfer recording sheet using a line dot type thermal head, the polyethylene terephthalate film was peeled off.
The recorded portion heated by the thermal head was transferred onto the imitation art paper, while the non-recorded portion was peeled off together with the film to obtain a positive image on the imitation art paper. The polyethylene terephthalate film could be easily peeled off, and no wrinkles were generated during recording with a thermal head.

Comparative Example 1 The film having the heat-sensitive transfer ink layer prepared in Example 1 was laminated on imitation art paper without a beeswax layer, and printed with a thermal head without calendering. During printing, misalignment occurred between the paper and film, and wrinkles also occurred.

[Example 2] On the surface of the imitation art paper used in Example 1, a sealing layer as described below was first applied, and then an ink adhesion adjustment layer was provided. (Filling layer) Film thickness after drying: 10 μm, roll coating method cyclized rubber Resin “Thermolite P”…3 parts Toluene…7 parts (Ink adhesion adjustment layer) Film thickness after drying: 0.5 μm, gravure coating method Cellulose acetate “ LAC70''...5 parts Cyclohexanone...30 parts Methyl cellosorgo...65 parts Subsequently, a heat-sensitive transfer ink layer was provided in the same manner as in Example 1, and a protective layer having the following composition was further laminated.
(Protective layer) Film thickness after drying: 2μ, roll coating polyurethane resin “Sample IB114B”
…10 parts PVC resin “Vinilite VAGH” (manufactured by UCC)
...5 parts vinyl acetate resin "S-Nil C-2" ...5 parts toluene ...20 parts MEK ...40 parts IPA ...20 parts xylene diisocyanate "Takenate D-
110N'' (manufactured by Takeda Pharmaceutical Co., Ltd.) ...1 part Lecithin (manufactured by Ajinomoto) ...0.4 parts Total 101.4 parts The heat-sensitive sheet thus obtained was subjected to thermal recording in the same manner as in Example 1, and the protective layer was peeled off. , a negative image was obtained. The protective layer was easily peeled off. Effects of the Invention When the thermal recording of the present invention is used, unlike recording methods using conventional thermal transfer ribbons, slip development does not occur in the thermal recording area in principle, which causes problems such as misregistration and scumming. Never. Furthermore, conventional thermal transfer requires two types of feeding mechanisms, paper feeding and ribbon feeding, but according to the present invention, only paper feeding is required, and the apparatus can be simplified.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing the structure of the heat-sensitive sheet of the present invention. Figures 2 and 3 are the first diagram explaining the mechanism for performing thermal recording using this.
FIG. 2 is a cross-sectional view similar to the figure, and FIG. 2 shows a positive printing mode, and FIG. 3 shows a negative printing mode. DESCRIPTION OF SYMBOLS 1... Thermal transfer sheet, 2... Support, 3... Ink adhesion adjustment layer, 4... Ink layer, 4A... Printing part, 4
B...non-printing area, 5...protective layer.

Claims (1)

[Scope of Claims] 1. A heat-sensitive recording sheet comprising an ink adhesion adjusting layer that increases or decreases ink adhesion by heating on the surface of a support, and an ink layer and a protective layer overlaid in this order. If the ink adhesion force adjusting layer increases the ink adhesion force by heating, the adhesion force of the ink layer to the support after heating is greater than the adhesion force between the ink layer and the protective layer. or, if the ink adhesion force adjusting layer reduces the ink adhesion force by heating, the adhesion force of the ink layer to the support after heating is smaller than the adhesion force between the ink layer and the protective layer. The adhesion force between each layer is selected so that when the protective layer is peeled off after heating with a thermal head, the printed part of the ink layer remains on the support and the non-printed part remains on the protective layer. The ink layer is removed together with the protective layer to produce positive printing, or the non-printing part of the ink layer remains on the support and the printed part is removed together with the protective layer to produce negative printing. A heat-sensitive recording sheet. 2. The thermal sensitive material according to claim 1 for positive printing, using a wax that melts when heated as the binder of the ink layer and using a natural or synthetic wax as the ink adhesion adjustment layer. Record sheet. 3. The heat-sensitive recording according to claim 1 for negative printing, using a wax that melts when heated as a binder for the ink layer and using a water or alcohol-soluble resin for the ink adhesion adjustment layer. sheet. 4. The heat-sensitive recording sheet according to claim 1, wherein a plastic film kneaded or coated with a lubricant and/or a heat release agent is used as the protective layer.