JPH0144513B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a heat-sensitive recording release paper. Conventionally, thermal recording paper is known which contains a leuco dye on the surface of a sheet-like support as a main component and an acidic substance that causes the leuco dye to develop color when heated, and this thermal recording paper is used as a thermal recording type packaging label. It is proposed to do so. 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 heat-sensitive recording paper, when plasticizers applied to plastic films, such as dioctyl phthalate (DOP) and dioctyl adipate (DOA), penetrate into the heat-sensitive coloring layer, the printed area (coloring area) disappears. Therefore, it cannot be used 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. Labels with weight values printed on them are pasted onto wraps, but in this case, if conventional thermal paper is used as the label, the label and wrap film can be stuck together by stacking the packaged items, etc. When this happens, 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. Therefore, from these points of view, heat-sensitive recording labels have superior advantages over labels printed using ink or ink ribbon, but they have not yet been put into practical use. The present inventors have conducted extensive research to overcome the above-mentioned drawbacks found in conventional heat-sensitive recording labels, and as a result, the present inventors have discovered that the surface of the heat-sensitive coloring layer further contains a thermosetting organic filler and an organic lubricant. The present inventors have discovered that the objective can be achieved by providing a water-soluble polymer protective layer, and have completed the present invention. That is, according to the present invention, a heat-sensitive coloring layer containing a leuco dye and an acidic substance that causes the leuco dye to develop color when heated is provided as a main component on the surface of the support, and an adhesive layer and a release mount are provided on the back surface of the support. There is provided a heat-sensitive recording type release paper characterized in that the heat-sensitive coloring layer is laminated with a water-soluble polymer layer containing a thermosetting organic filler and an organic lubricant on the surface of the heat-sensitive color forming layer. The heat-sensitive recording type release paper in the present invention is capable of printing or recording images on the surface of the paper using a heating method, and can be attached to a solid surface by peeling off the release liner attached to the back side. 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. The heat-sensitive recording type release paper according to the present invention is characterized in that a water-soluble polymer layer containing a thermosetting organic filler and an organic lubricant is provided on the surface of the heat-sensitive color forming layer. In this case, the water-soluble polymer in the protective layer prevents the plasticizer in the wrap film from penetrating into the thermosensitive coloring layer, and the thermosetting organic filler prevents parents from touching the thermal printer head when printing with a thermal printer. The organic lubricant exhibits the effect of preventing sticking (staking phenomenon) and suppressing the wear of the thermal printer head caused by the inclusion of the thermosetting organic filler. The thickness of the protective layer is usually 1 to 10 microns, preferably 2 to 5 microns. In the present invention, various water-soluble polymers such as those shown below are used. Polyvinyl alcohol, hydroxyethylcellulose, methylcellulose, carboxymethylcellulose, starch and its derivatives, casein,
Sodium alginate, polyvinylpyrrolidone, polyacrylamide, styrene-maleic acid copolymer. The amount of water-soluble polymer used in the protective layer is 20 to 80% by weight, preferably 40 to 60% by weight. Moreover, this water-soluble polymer can be used together with a conventional water-resistant agent that can make it water-resistant. In the present invention, a thermosetting organic filler is defined as one that hardens by heating when thermal printing is performed using a thermal printer, and specific examples of such fillers include the following. Urea-formalin resin, phenol resin, polycarbonate resin, melamine resin, etc. The amount of this thermosetting organic filler used is 5% in the protective layer.
~40% by weight, preferably 20-30% by weight. The organic lubricant used in the present invention includes various organic solids with smooth surfaces, such as animal waxes such as beeswax and serratus wax, vegetable waxes such as carnauba wax, and paraffin waxes. Petroleum waxes such as waxes and microcrystalline waxes, polyethylene waxes, and other synthetic waxes, such as polyhydric alcohol esters of higher fatty acids, higher ketones, higher amides, condensates of higher fatty acids and amines, synthetic paraffins, and chlorine. Examples include chlorinated paraffins, condensates of aromatic carboxylic acids and higher aliphatic amines, and condensates of aromatic amines and higher fatty acids. These organic lubricants are used in the form of fine powder or emulsion, and the amount used is 20 to 60% by weight, preferably 30 to 50% by weight in the protective layer. To produce the heat-sensitive release paper of the present invention, a conventional heat-sensitive color forming layer containing a leuco dye, an acidic substance, a binder, a heat sensitivity enhancer, a filler, etc. is applied to the surface of a paper-like support such as paper or synthetic paper. After the components are coated and dried, protective layer components such as a water-soluble polymer, a thermosetting organic filler, an organic lubricant, and if necessary a water-resistant agent are further coated and dried on the top surface. On the other hand, an adhesive layer is provided on the back side of the support by a conventional method so that it can be applied to a solid surface such as a wrap film or wrapping paper, and a release mount is applied to the surface. In the present invention, a water-soluble polymer layer can be further provided as a second protective layer between the back surface of the support and the adhesive layer. The use of this second protective layer means that when the release paper of the present invention is applied to a plastic film such as a wrap film, the plastic film is transferred from the applied plastic film to the thermosensitive coloring layer through the adhesive layer and the support. Penetration of the agent can be prevented. Of course, such a plasticizer penetration prevention effect can also be obtained when a water-soluble resin adhesive layer is used. As the water-soluble polymer used for forming the second protective layer, the same ones as those described for the first protective layer can be used. The thermosensitive coloring layer used in the present invention contains a leuco dye, an acidic substance, a binder, etc., and the components for forming the thermosensitive coloring layer will be specifically described below. (A) Leuco dye As the leuco dye, the leuco forms of the various dyes shown below, which are usually colorless or light-colored, are used.
In particular, triphenylmethane type, fluoran type,
It is preferable to use leuco forms of phenothiazine-based, auramine-based, and spiropyran-based dyes. 3,3-bis(P-dimethylaminophenyl)-6-dimethylaminophthalide 3,3-bis(P-dimethylaminophenyl)phthalide 3,3-bis(P-dimethylaminophenyl)-6- Diethylaminophthalide 3,3-bis(P-dimethylaminophenyl)-6-chlorophthalide 3-(N-P-tolyl-N-ethylamino)-
6-Methyl-7-(N-phenylamino)fluoran 3-diethylamino-7-chlorofluoranbenzoylleucomethylene blue-6'-chloro-8'-methoxy-benzoindolino-pyrylospirane 6'-bromo-8'-methoxy -benzoindolino-pyrylospirane 2-[3,6-bis(diethylamino)-9-
(o-chloroanilino)xantyl]benzoic acid lactam. (B) Acidic Substances The following various acidic substances can be used as acidic substances that react with the leuco dye described above when heated to cause it to develop color. (a) Organic and inorganic acids boric acid, oxalic acid, maleic acid, tartaric acid,
Citric acid, succinic acid, benzoic acid, stearic acid, gallic acid, salicylic acid, 1-hydroxy-2-naphthoic acid, o-hydroxybenzoic acid, m-hydroxybenzoic acid, 2-hydroxy-p-toluic acid. (b) 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-
Octinol, 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. (C) Binder The following various binders can be used to bind and support the thermosensitive coloring layer on the support. Water-soluble materials such as polyvinyl alcohol, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, polyvinylpyrrolidone, polyacrylamide, polyacrylic acid, starch, gelatin, etc., or polystyrene, vinyl chloride-vinyl acetate copolymer, polybutyl methacrylate, etc. Aqueous emulsions such as . In addition, in the heat-sensitive coloring layer, if necessary, conventional auxiliary additives such as calcium carbonate, silica, alumina, magnesia, talc,
Fine powders such as titania, barium sulfate, and aluminum stearate can be added to improve the clarity of colored images. Further, a heat sensitivity increasing agent such as a higher fatty acid amide can be included. Unlike conventional thermal paper that is simply used for labels and stickers, the products of the present invention are not affected by the plasticizers contained in plastic films such as wrap films, and are also resistant to printing by label printers. This method has the advantage that deposits on the thermal head, staking, etc. are prevented, and wear on the thermal head is significantly reduced. Next, the present invention will be explained in more detail with reference to Examples. Example The following components were pulverized and dispersed for 24 hours using a ball mill to prepare dispersions A and B, and then dispersions A and B were further mixed to prepare a heat-sensitive color forming liquid. Liquid A: Crystal Violet Lactone 1.5 parts by weight polyvinyl alcohol (20% aqueous solution)
5.0 〃 Water 43.5 〃 B solution: Bisphenol A 6.0 parts by weight Calcium carbonate 3.0 〃 Stearic acid amide 1.0 〃 Polyvinyl alcohol (20% aqueous solution)
10.0 〃 Water 10.0 〃 The thermosensitive color forming liquid prepared as above,
It was applied and dried on the surface of high-quality paper (approximately 50 g/cm ² ) to form a heat-sensitive coloring layer with a coating weight of 5 g/m ² . Next, the following components were mixed to prepare liquid C for forming a protective layer. Liquid C: Polyvinyl alcohol (20%) 5.0 parts by weight Thermosetting organic filler (Mitsui Toatsu VF filler)
(25%) (Compound name: urea-formalin resin)
2.5 〃 Montan wax 2.5 〃 Apply the above C solution on the heat-sensitive coloring layer at a dry weight of 2 g/m ²
It was coated and dried, and the surface was treated with super calender to form a protective layer. Next, a pressure-sensitive adhesive layer is formed on the silicone resin surface of a release mount formed by coating silicone resin on high-quality paper (approximately 50 g/m ² ), and heat-sensitive recording paper is applied on the adhesive layer surface. The back sides of the paper were bonded together to obtain a heat-sensitive recording type release paper (sample E-1). Next, for comparison, a release paper (sample C-
1) was obtained. In addition, a protective layer formed in the same manner as described above except that the thermosetting organic filler and Montan wax were not contained (Sample C-
2), and one formed in the same manner as above except that the protective layer did not contain montan wax (sample C-3). The four types of samples obtained as described above were printed using a printer with a line head, and the matching properties and plasticizer resistance were tested. The results are shown in Table 1. The test method and evaluation are as follows. Color density...Print with a printer and use Macbase RD
The concentration was measured at -514. States King...Tests adhesion to thermal heads. Abrasion property: A length of 1 km was printed continuously, and the degree of abrasion of the thermal head was measured using a micrometer. Plasticizer resistance: Printed with a printer, covered with vinyl chloride wrap film, and measured the decrease in print density.

[Table] ◎...Very good, ○...Good, △...Slightly good,
×...Poor As described above, it can be seen that the thermal paper of this example is free from discoloration due to vinyl chloride wrap, etc., and has excellent matching properties with a thermal head.

Claims (1)

[Scope of Claims] 1. A heat-sensitive coloring layer containing a leuco dye and an acidic substance that causes the leuco dye to develop color when heated is provided as a main component on the surface of the support, and an adhesive layer and a release mount are laminated on the back surface of the support. and a water-soluble polymer layer containing a thermosetting organic filler and an organic lubricant is provided on the surface of the thermosensitive coloring layer. 2. The release paper according to claim 1, wherein a water-soluble polymer layer is interposed between the back surface of the support and the adhesive layer.