JPH0221249Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The present invention relates to a heat-sensitive recording release paper. Conventionally, heat-sensitive recording paper containing a leuco dye and an acidic substance that causes the leuco dye to develop color when heated on the surface of a sheet-like support as a main component is known.
It has been proposed to use this heat-sensitive recording paper as a heat-sensitive recording type packaging label. In the case of such heat-sensitive recording type labels, since the printing method is based on a thermal head, it has the advantage of being easier and more beautiful than conventional printing methods using ink or ink ribbon. There is.
However, in the case of thermosensitive recording paper, when the plasticizer applied to the plastic film, such as dioctyl phthalate (DOP) or dioctyl adipate (DOA), penetrates into the thermosensitive coloring layer,
There is a problem that the printed part (coloring part) fades,
It cannot be applied as a label for plastic film packaging products. For example, in mass retailers such as supermarkets, in order to sell fresh foods, fish, vegetables, meat, etc. are placed in plastic trays such as Styrofoam, and the entire tray is overlapped with plastic film such as polyvinyl chloride. A label with the weight value printed on it is pasted onto the wrap.In this case, if conventional thermal paper is used as the label, the label and wrap film may be separated by stacking the packaged items. When the label is placed in close contact with the label, the plasticizer in the wrap film penetrates into the heat-sensitive color forming layer on the label surface, and after a certain period of time, the printing on the label surface disappears, causing a major hindrance to product sales. As a heat-sensitive recording material for such release paper,
A thermosensitive coloring layer containing a coloring agent made of a leuco dye and a coloring agent made of an acidic substance such as an organic acid or a phenolic compound that causes the leuco dye to develop color when heated is provided on a support; It is known that a protective layer (a water-soluble polymer layer) is provided on the top and back surfaces of the glass. However, if a label is attached to plastic film for a long time,
The plasticizer penetrated from the back side of the label, causing a discoloration phenomenon, making it unsatisfactory as a thermal label. The inventors of the present invention have conducted intensive research to overcome these drawbacks, and have found that the above drawbacks can be overcome by providing an undercoat layer made of a water-soluble polymer on the back surface of the heat-sensitive recording layer. That is, according to the present invention, a heat-sensitive color forming layer containing a leuco dye and a color developer therefor is provided on the surface of a support, and an adhesive layer and a release mount are laminated on the back surface of the support. A water-soluble polymer layer is provided between the surface of the support and the heat-sensitive coloring layer and between the back surface of the support and the adhesive, and the surface of the heat-sensitive coloring layer is further coated with a water-soluble polymer layer. A heat-sensitive recording type release paper is provided. As shown in the drawings, the release paper of the present invention has a water-soluble polymer layer 1-1, a thermosensitive coloring layer 2 containing a leuco dye and a color developer, and a water-soluble polymer layer 1-1 on the surface of a support 3. -2 are laminated in that order, and further support 3
It has a structure in which a water-soluble polymer layer 1-3 is provided on the back surface, and a release mount 5 is laminated thereon via an adhesive layer 4. The heat-sensitive recording type release paper in this invention is capable of printing or recording images on the surface of the paper using a heating method, and by peeling off the release liner attached to the back side, it can be applied to a solid surface. It refers to sheets that can be glued together, and can be used for various types of labels such as number tags, price tags, medicine bottle tags, labels, etc.
Includes name plates, stickers, etc. In the present invention, water-soluble polymer layers are provided on the front and back surfaces of the heat-sensitive coloring layer and on the back surface of the support, and there are various types of water-soluble polymers as shown below. The thickness of the polymer layer is usually 1
~10μ, preferably 2-5μ. Examples of water-soluble polymers: polyvinyl alcohol, hydroxyethylcellulose, methylcellulose, carboxymethylcellulose, starch and its derivatives, casein,
Sodium alginate, polyvinylpyrrolidone, polyacrylamide, styrene-maleic acid copolymer, etc. This water-soluble polymer can be used together with a conventional water-resistant agent that can make it water-resistant, such as formalin, glyoxazole, chromium alum melamine, melamine-formalin, polyamide resin, polyamide-epichlorohydrin resin. etc. are punched. In the present invention, wax, other wax-like substances, organic fillers, etc. can be added to the water-soluble polymer layer on the surface of the thermosensitive coloring layer in order to improve the matching property with the thermal head. In the present invention, the undercoat layer provided between the heat-sensitive coloring layer and the surface of the support can contain inorganic and organic fillers, but it is particularly advantageous to contain organic fillers. There was found. In the present invention, since the surface of the heat-sensitive coloring layer is covered with an overcoat layer, there is a problem in that the heat-sensitive coloring property is poor, but this problem can be solved by particularly including an organic filler in the undercoat layer. In this undercoat layer, the organic or inorganic filler content is 1 to 20% by weight.
is appropriate. Further, the amount of the undercoat layer to be deposited is suitably about 0.3 to 5 g/m ² . Specific examples of organic fillers include phenolic resin,
Various organic fine particles such as urea-formalin resin, polycarbonate, melamine resin, polystyrene, and polypropylene are crushed. Examples of inorganic fillers include calcium carbonate, magnesium carbonate, alumina, silica, talc, magnesium hydroxide, aluminum hydroxide, and the like. As the leuco dye used in the present invention, commonly used triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based, and spiropyran-based leuco dyes are preferably used. For example, 3-{N-(p-tolylamino)}-7-aniline Linofluorane, 3-{N-
(p-tolyl)-N-methylamino}-7-anilinofluorane, 3-{N-(p-tolyl)-N-ethylamino}-7-anilinofluorane, 3-{N
-(p-tolyl)-N-propylamino}-7-anilinofluorane, 3-{N-(p-tolyl)-N
-butylamino}-7-anilinofluorane, 3
-dimethylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7
-anilinofluorane, 3-dipropylamino-
6-Methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 3-piperidino-6-methyl- 7-
Anilinofluorane, 3-piperazino-6-methyl-7-anilinofluorane, 3-N-(N'-methylpiperazino)-6-methyl-7-anilinofluorane, 3-morpholino-6-methyl- 7-anilinofluorane, 3-dibenzylamino-6-
Methyl-7-anilinofluorane, 3-(N-methyl-N-cyclohexyl)-6-methyl-7-
Anilinofluorane, 3-(N-cyclohexylamino)-6-methyl-7-anilinofluorane,
3-diethylamino-7-(o-chloroanilino)
Examples include fluoran, 3-dibutylamino-7-(o-chloroanilino)fluoran, and 3-diisopropyl-7-(o-chloroanilino)fluoran. In addition, as the color developer used in the present invention, various electron-accepting substances that react with the leuco dye and develop color when heated are used, and specific examples thereof include the following phenolic dyes. Substances, inorganic acidic substances, organic acidic substances, or their salts are included. Phenolic substances; 3,5-xylenol, thymol, p-tert-
Butylphenol, 4-hydroxyphenoxide, methyl-4-hydroxybenzoate, 4-
Hydroxyacetophenone, α-naphthol, β
- Naphthol, catechol, resorcinol, hydroquinone, 4-tert-octylcatechol, 4,4
-sec-butylidenephenol, 2,2'-dihydroxydiphenyl, 2,2-methylenebis(4-
methyl-6-tert-butylphenol), 2,2
-bis(4-hydroxyphenyl)propane,
4,4-isopropylidene-bis(2-tert-butylphenol), 4,4-sec-butylidene diphenol, pyrogallol, phloroglucin, phloroglucin carboxylic acid, 4-tert-octylphenol, 4-phenylphenol, 2,2-bis(p-hydroxyphenyl)butane, 4,4'-cyclohexylidene diphenol, 2,2-bis(2,5-dibromo-4-hydroxyphenyl)
Propane, 4,4'-isopropylidene bis(2-
tert-butylphenol), 2,2'-methylenebis(4-chlorophenol), etc. Acidic substances or salts thereof; benzoic acid, gallic acid, salicylic acid, zinc salicylate, 1-hydroxy-2-naphthoic acid, o-hydroxybenzoic acid, m-hydroxybenzoic acid, p
-benzyl hydroxybenzoate, 2-hydroxy-
p-toluic acid, tartaric acid, oxalic acid, maleic acid, citric acid, succinic acid, stearic acid, 4-oxydiphthalic acid, boric acid, etc. These leuco dyes are used to form a thermosensitive coloring layer.
A binder is used in addition to the color developer. A wide variety of known binders can be used, and specific examples include polyvinyl alcohol, methoxycellulose, hydroxycellulose, carboxymethylcellulose, carboxyethylcellulose, polyvinylpyrrolidone, polyacrylamide, starch, and gelatin. In addition, in combination with these water-soluble binders, for example, styrene-butadiene copolymer, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyacrylic acid ester, polymethacrylic acid ester such as polybutyl methacrylate, etc. latexes can also be used. The heat-sensitive coloring layer also contains silica, magnesia,
Talc, calcium carbonate, barium sulfate, urea
It is desirable to improve the clarity of colored images by adding fine powder such as formalin resin or styrene resin. In addition, when coating and forming a heat-sensitive coloring layer on a support or a lower heat-sensitive coloring layer, antifoaming agents, wetting agents (surfactants), waxes, softening point regulators, etc. may be added to the heat-sensitive coloring layer forming liquid. It can be added to improve coatability and thermal response. To obtain the product of the present invention, a layer of water-soluble polymer is provided on both sides of the support, then a heat-sensitive recording layer is provided on top of that, and an overcoat layer of water-soluble polymer is further provided on top of that, and the support is An adhesive layer is provided on the back side of the body by a conventional method so that it can be applied to a solid surface such as a wrap film, wrapping paper, etc., and a release paper is applied to the surface of the adhesive layer to obtain a heat-sensitive recording type release paper. Next, the present invention will be explained with reference to examples. Example 1 Solution A was coated on the front and back sides of a support having a basis weight of 52 g/m ² and dried so that the amount of adhesion upon drying was 3 g/m ² . (Liquid A) Polyvinyl alcohol 5.0 parts Water 50 parts Next, each of the mixtures having the following formulations was pulverized and dispersed in a magnetic ball mill for 24 hours to prepare Liquids B and C. (Liquid B) 3-(N-ethyl-N-p-tolyl)-6-methyl-7-anilinofluorane 150 parts 5% polyvinyl alcohol aqueous solution 150 parts Water 200 parts (Liquid C) Bisphenol A 120 parts Stearin Acid amide 120 parts 5% polyvinyl alcohol aqueous solution 120 parts Water 200 parts 10 parts of this B solution, 20 parts of C solution and 20% as a binder
A heat-sensitive coating solution was prepared by mixing 20 parts of polyvinyl alcohol. This liquid was applied and dried on the undercoat layer of the support so that the dry weight was 5 g/m ² ,
Next, an overcoat coating liquid consisting of the D liquid formulation was applied and dried to a dry weight of 5 g/m ² . (Liquid D) Carboxy group-modified polyvinyl alcohol
5.0 parts Thermosetting organic filler 1.0 parts Waterproofing agent 0.5 parts Water 50 parts Example 2 In Example 1, liquid A was applied to the back side of the support and dried, and then liquid A' shown below was applied to the surface of the support. A product was obtained in the same manner, except that the coating was applied and dried so that the dry weight was 2 g/m ² . (Liquid A') Polystyrene organic filler 1.0 parts PVA 5.0 parts Water 50 parts Example 3 A product was obtained in the same manner as in Example 2 except that inorganic calcium carbonate was used instead of the organic filler in the undercoat layer. Comparative Example 1 A product was obtained in the same manner as in Example 1 except that the undercoat layer on the lower surface of the heat-sensitive coloring layer was removed. Comparative Example 2 In Example 1, in the undercoat layer forming liquid on the lower surface of the thermosensitive coloring layer, instead of the water-soluble polymer,
A product was obtained in the same manner except that SBR (styrene/butadiene rubber) emulsion was used. Next, after surface-treating the above product with Super Calender, a release paper coated with silicone resin with an adhesive layer on the silicone resin side is pasted onto the back side via the adhesive layer. Combined,
Then, it was punched out to an appropriate size to obtain a heat-sensitive recording type release paper. The obtained product was subjected to a color development test by being colored using a label printer equipped with a built-in thermal head, and the color erasing property of the printed area using a plasticizer was also tested. Furthermore, the background color development of the sample of the printed area was also tested. The results are shown in Table-1.

[Table] From the results in Table 1, it can be seen that the product of the present invention has excellent color development, does not stain the background, and is of high quality that is not discolored by plasticizers. In addition, it was found that color development was significantly improved by using an organic filler in the undercoat layer. It shows the same color density as when used.

[Brief explanation of the drawing]

The drawing is an explanatory cross-sectional view of the heat-sensitive recording type release paper of the present invention. Symbols in the figure: 1-1, 1-2, 1-3...water-soluble polymer layer, 2...thermosensitive coloring layer, 3...support, 4...adhesive layer, 5...peelable mount.

Claims (1)

[Claims for Utility Model Registration] (1) A heat-sensitive coloring layer containing a leuco dye and a color developer therefor is provided on the surface of the support, and an adhesive layer and a release mount are laminated on the back of the support. A water-soluble polymer layer is provided between the surface of the support and the thermosensitive coloring layer and between the back surface of the support and the adhesive, and the surface of the thermosensitive coloring layer is further covered with a water-soluble polymer layer. A heat-sensitive recording release paper characterized by: (2) The release paper according to claim 1 of the utility model registration, wherein the water-soluble polymer layer between the surface of the support and the thermosensitive coloring layer contains an organic filler.