JP2020175556A - Thermosensitive-recording linerless label - Google Patents

Abstract

To provide a thermosensitive-recording linerless label excellent in color developing sensitivity, image preservability after a long term storage and background fogging resistance.SOLUTION: There is provided a thermosensitive-recording linerless label which has a thermosensitive recording layer containing at least a dye precursor and a developer on one surface of a support, a release layer without a protective layer on the thermosensitive recording layer and an adhesive layer on the other surface of the support, wherein the thermosensitive recording layer contains a specific developer and the adhesive layer contains a hot melt adhesive.SELECTED DRAWING: None

Description

The present invention relates to a heat-sensitive recording linerless label having excellent color development sensitivity, image storage stability after long-term storage, and skin fog resistance.

The heat-sensitive recording material generally contains an electron-donating dye precursor (hereinafter referred to as a dye precursor) and an electron-accepting color developer (hereinafter referred to as a color developer) on a support as main components. By having a heat-sensitive recording layer and heating with a heat head, a heat pen, a laser beam, or the like, the dye precursor and the color developer react instantly to obtain a recorded image. In recent years, heat-sensitive recording materials have been subjected to adhesive processing and are increasingly used for label applications.

Conventionally, a heat-sensitive recording label has a structure in which an adhesive layer and a release paper (liner) are laminated on a support on the side opposite to the heat-sensitive recording layer (on the support on the side opposite to the heat-sensitive recording layer described above). , A general adhesive sheet is attached), and when the thermal recording label is attached to an object, the release paper is peeled off to expose the adhesive layer, and then only pressure is applied. Since it can be easily bonded, it is widely used in the fields of food and distribution, for example. However, the release paper that was peeled off was almost always disposed of.

On the other hand, in the thermal recording linerless label, a release paper having a release property is formed on the surface of the thermal recording layer and wound up, so that a release paper is not provided on the adhesive layer on the side opposite to the thermal recording layer. However, in recent years, it has been preferably used because it is possible to impart the same handleability as a conventional heat-sensitive recording label and the amount of waste is significantly reduced.

However, in the heat-sensitive recording linerless label, the surface of the surface having the heat-sensitive recording layer is coated with a releasable silicone resin or the like to form a release layer, so that the silicone resin or the like penetrates into the heat-sensitive recording layer. As a result, problems such as deterioration of color development sensitivity and image storage stability after long-term storage, or background fog may occur. Therefore, there has been a demand for a heat-sensitive recording linerless label having excellent color development sensitivity, image storage stability after long-term storage, and skin fog resistance.

Japanese Unexamined Patent Publication No. 2008-23171 (Patent Document 1) describes an adhesive label for thermal recording in which an adhesive layer and a release paper are sequentially laminated on the surface opposite to the side having the thermal recording layer. As the release agent layer of the release paper, a thermal recording label having a release agent layer obtained by heat-curing a solvent-free silicone resin is described. However, when a release layer obtained by thermosetting a solvent-free silicone resin is provided on the heat-sensitive recording layer of the heat-sensitive recording linerless label, the color development sensitivity and the image storage stability after long-term storage may be deteriorated as described above. There was also a problem that it was easy to cause skin fog.

Japanese Unexamined Patent Publication No. 2013-121718 (Patent Document 2) describes a heat-sensitive recording label having a barrier layer provided on the heat-sensitive recording layer and a release layer obtained by thermosetting a solvent-free silicone resin on the barrier layer. Has been done. When a barrier layer is provided between the heat-sensitive recording layer and the release layer, the penetration of the silicone resin into the heat-sensitive recording layer is reduced, but the barrier layer may cause a problem that the color development sensitivity is lowered.

Japanese Unexamined Patent Publication No. 2014-32241 (Patent Document 3) describes a linerless label having a release layer obtained by UV-curing a compound containing a cation-curable UV-curable silicone resin on a paper substrate. .. Since the UV-curable silicone resin cures quickly, when a release layer containing the UV-curable silicone resin is formed on the heat-sensitive recording layer, the silicone resin does not easily penetrate into the heat-sensitive recording layer, resulting in color development sensitivity and long-term storage. Deterioration of image storage stability is unlikely to occur. However, even when a release layer containing an ultraviolet curable silicone resin is formed on the heat-sensitive recording layer, it is difficult to completely suppress the penetration of the silicone resin into the heat-sensitive recording layer, and the color development sensitivity and image storage stability after long-term storage are difficult. The problem of lowering the resin has not been solved.

On the other hand, Japanese Patent Application Laid-Open No. 2017-177627 (Patent Document 4) describes 4,4'-dihydroxydiphenylsulfone or 4-hydroxy-4'-as a color developer in the heat-sensitive recording layer for the purpose of improving color development sensitivity. A thermal recording linerless label containing allyloxydiphenyl sulfone is described. However, the heat-sensitive recording linerless label has low image storage stability after long-term storage, and the color development sensitivity is not sufficiently satisfactory.

Japanese Unexamined Patent Publication No. 2008-23171 Japanese Unexamined Patent Publication No. 2013-121718 JP-A-2014-32241 JP-A-2017-177627

An object of the present invention is to provide a heat-sensitive recording linerless label having excellent color development sensitivity, image storage property after long-term storage, and skin fog resistance.

The above-mentioned problems are solved by the following inventions.
(1) One surface of the support has a heat-sensitive recording layer containing at least a dye precursor and a color developer, and a release layer on the heat-sensitive recording layer containing an ultraviolet curable silicone resin without a protective layer. A heat-sensitive recording linerless label having an adhesive layer on the other surface of the support, wherein the heat-sensitive recording layer is a bis (3-allyl-4-hydroxyphenyl) sulfone or 3 as a color developer. A thermal recording linerless label comprising − (3-tosyl ureido) phenyl-p-toluenesulfonate, the pressure-sensitive adhesive layer containing a hot-melt pressure-sensitive adhesive.
(2) The heat-sensitive material according to (1) above, wherein the release layer contains an organopolysiloxane compound having an acrylic group and / or a methacrylic group as a functional group in the molecule as an ultraviolet curable silicone resin. Recording linerless label.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a heat-sensitive recording linerless label having excellent color development sensitivity, image storage stability after long-term storage, and skin fog resistance.

Hereinafter, the contents of the present invention will be specifically described.

In the present invention, the support of the heat-sensitive recording linerless label may be transparent, translucent, or opaque, and the support includes paper, various non-woven fabrics, woven fabrics, synthetic resin films, and synthetic resins. Laminated paper, synthetic paper, metal foil, ceramic paper, etc., or a composite sheet in which these are combined are exemplified. Among them, the paper support is preferable because a so-called heat-sensitive recording linerless label having good hand-cutting property can be obtained, which can be easily cut, and since the water content can be easily controlled, paper such as acid-free paper and acid paper can be obtained. A support is particularly preferably used. Examples of the paper machine for making paper on the paper support include a long net type paper machine, a gap former type paper machine, a circular net type paper machine, a short net type paper machine, and the like, which can be appropriately selected and used. it can. In addition, surface size treatment is performed on a paper support such as acid-free paper or acid paper using natural adhesives such as starch known by various size press machines and roll coaters, synthetic adhesives such as polyvinyl alcohol, and various sizing agents. It is also possible to do.

Pulps used in the production of paper supports include coniferous bleached kraft pulp (NBKP), broadleaf bleached kraft pulp (LBKP), coniferous bleached sulfite pulp (NBSP), broadleaf bleached sulfite pulp (LBSP), TMP, CTMP. , BCTMP, GP, RGP, CGP, various pulps such as cotton pulp, various waste paper pulps such as DIP, and non-wood fibers such as Kenaf, but are not limited to these, and one kind as needed. , Or two or more types can be used.

As the filler contained in the paper support, a known filler can be appropriately selected and used. Examples of such fillers include inorganic fillers such as calcium carbonate, talc, kaolin, calcined kaolin, amorphous silica, illite, clay, calcined clay, and titanium dioxide, and organic fillers such as plastic pigments. However, the present invention is not limited to these, and one type or two or more types can be used as required.

The paper support may contain a sizing agent for internal addition (internal sizing agent), and in the case of acidic paper making, the reinforced rosin sizing agent, emulsion sizing agent, synthetic sizing agent, etc. are used in the case of neutral paper making. , Alkylketen dimer type, alkenyl anhydride succinic acid type, higher fatty acid type, neutral rosin sizing agent and the like can also be contained. Further, as the sizing agent for internal addition, one kind or two or more kinds can be used as needed. On the other hand, as the sizing agent for external addition (external sizing agent), cationic polymers such as styrene maleic acid-based copolymer resin and styrene acrylic acid-based copolymer resin, anionic polymers, styrene-based polymers, and isocyanates are used. Cationic polymers such as based polymers, alkyd resin saponified products such as rosin, tall oil and phthalic acid, anionic low molecular weight compounds such as petroleum resin and saponified products of rosin, α-olefin-maleic acid based copolymer resin, acrylic Examples thereof include acid ester-acrylic acid-based copolymer resins and alkyl keten dimers, but the present invention is not limited to these, and one or more external sizing agents may be used as necessary. Can be done.

Further, in addition to the above-mentioned sizing agents, the paper support includes various papermaking aids exemplified by nonionic, cationic, anionic or amphoteric yield improvers, drainage improvers, paper strength enhancers and the like. The agent can be contained as needed. Specific examples of the yield improver, drainage improver, and paper strength enhancer include polyvalent metal compounds such as aluminum (specifically, aluminum sulfate, aluminum chloride, sodium aluminate, basic aluminum compounds, etc.). , Amorphous silica, various starches, urea resin, polyamide / polyamine resin, polyethyleneimine, polyacrylamide, polyamine, polyvinyl alcohol, polyethylene oxide and the like can be exemplified.

In the present invention, the heat-sensitive recording layer of the heat-sensitive recording linerless label contains bis (3-allyl-4-hydroxyphenyl) sulfone or 3- (3-tosylureide) phenyl-p-toluenesulfonate as a color developer. .. By containing bis (3-allyl-4-hydroxyphenyl) sulfone or 3- (3-tosylureide) phenyl-p-toluenesulfonate in the heat-sensitive recording layer, the color development sensitivity and image storage stability after long-term storage can be improved. An excellent heat-sensitive recording linerless label can be obtained. Among them, bis (3-allyl-4-hydroxyphenyl) sulfone is preferable because it can obtain a heat-sensitive recording material having particularly excellent color development sensitivity.

In the present invention, in order to obtain sufficient color development, bis (3-allyl-4-hydroxyphenyl) sulfone or 3- (3-tosylureide) phenyl-p-toluenesulfone is contained in the total solid content of the thermal recording layer. The content of nat is preferably 15 to 50% by mass. The ratio of bis (3-allyl-4-hydroxyphenyl) sulfone or 3- (3-tosylureide) phenyl-p-toluenesulfonate to the total amount of the developer is preferably 50% by mass or more.

In the present invention, the thermal recording layer contains a dye precursor together with the above-mentioned color developer. The dye precursor contained in the heat-sensitive recording layer is generally represented by a pressure-sensitive recording material or a dye precursor used for a heat-sensitive recording material, but one or more of them are used in an appropriate combination. Specific examples include those listed below, but the present invention is not limited thereto.

As black dye precursors, 3-di-n-butylamino-6-methyl-7-anilinofluorane, 3-di-n-pentylamino-6-methyl-7-anilinofluorane, 3 -Diethylamino-6-methyl-7-anilinofluorane, 3-di-n-butylamino-7- (2-chloroanilino) fluorane, 3-diethylamino-7- (2-chloroanilino) fluorane, 3-diethylamino-6 -Methyl-7-xylidinofluorane, 3-diethylamino-7- (2-carbomethoxyphenylamino) fluorane, 3- (N-cyclohexyl-N-methyl) amino-6-methyl-7-anilinofluorane, 3- (N-cyclopentyl-N-ethyl) amino-6-methyl-7-anilinofluorane, 3- (N-isoamyl-N-ethyl) amino-6-methyl-7-anilinofluorane, 3- (N-ethyl-4-toluidino) -6-methyl-7-anilinofluorane, 3- (N-ethyl-4-toluidino) -6-methyl-7- (4-toluidino) fluorane, 3- (N) -Methyl-N-tetrahydrofurfuryl) Amino-6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7- (4-) n-butylphenylamino) fluorane, 3-piperidino-6-methyl-7-anilinofluorane, 3- (N-ethyl-N-isopentyl) amino-6-methyl-7-anilinofluorane,

As red dye precursors, 3,3-bis (1-n-butyl-2-methylindol-3-yl) phthalide and 3,3-bis (1-n-butyl-2-methylindol-3) -Il) tetrachlorophthalide, 3,3-bis (1-n-butylindol-3-yl) phthalide, 3,3-bis (1-n-pentyl-2-methylindol-3-yl) phthalide, 3,3-bis (1-n-hexyl-2-methylindol-3-yl) phthalide, 3,3-bis (1-n-octyl-2-methylindole-3-yl) phthalide, 3,3-bis Bis (1-methyl-2-methylindol-3-yl) phthalide, 3,3-bis (1-ethyl-2-methylindol-3-yl) phthalide, 3,3-bis (1-propyl-2-yl) Methylindole-3-yl) phthalide, 3,3-bis (2-methylindole-3-yl) phthalide, Rhodamine B-anilinolactam, Rhodamine B- (o-chloroanilino) lactam, Rhodamine B- (p-nitroanilino) ) Lactam, 3-diethylamino-5-methyl-7-dibenzylaminofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-6-methoxyfluorane, 3-diethylamino-6-methyl Fluolan, 3-diethylamino-6-methyl-7-chloro-8-benzylfluolane, 3-diethylamino-6,7-dimethylfluorane, 3-diethylamino-6,8-dimethylfluorane, 3-diethylamino-7 -Chlorofluorane, 3-diethylamino-7-methoxyfluorane, 3-diethylamino-7- (N-acetyl-N-methyl) aminofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7- n-propoxyfluorane, 3-diethylamino-7-p-methylphenylfluorane, 3-diethylamino-7,8-benzofluorane, 3-diethylaminobenzo [a] fluorane, 3-diethylaminobenzo [c] fluorane, 3 -Dimethylamino-7-Methylfluorane, 3-dimethylamino-6-methyl-7-chlorofluorine, 3-dimethylamino-7-methylfluorane, 3-dimethylamino-7-chlorofluorine, 3-( N-ethyl-p-toluidino) -7-methylfluorane, 3- (N-ethyl-N-isoamyl) amino-6-methyl-7-chlorofluorane, 3- (N-ethyl-N-isoamyl) Amino-7,8-benzofluorane, 3- (N-ethyl-N-isoamyl) amino-7-methylfluorane, 3- (N-ethyl-Nn-octyl) amino-6-methyl-7- Chlorofluorane, 3- (N-ethyl-Nn-octyl) amino-7,8-benzofluorane, 3- (N-ethyl-Nn-octyl) amino-7-methylfluorane, 3- (N-Ethyl-Nn-Octyl) Amino-7-Chlorofluorane, 3- (N-Ethyl-N-4-Methylphenyl) Amino-7,8-Benzofluorane, 3- (N-ethoxyethyl) -N-Ethyl) Amino-7,8-Benzofluorane, 3- (N-Ethyl-N-Ethyl) Amino-7-Chlorofluorane, 3-n-dibutylamino-6-Methyl-7-Chloroflu Olan, 3-n-dibutylamino-7,8-benzofluorine, 3-n-dibutylamino-7-chlorofluorane, 3-n-dibutylamino-7-methylfluorane, 3-diallylamino-7, 8-Benzofluorane, 3-diallylamino-7-chlorofluorine, 3-di-n-butylamino-6-methyl-7-bromofluorine, 3-cyclohexylamino-6-chlorofluorine, 3-pyrroli Dylamino-7-methylfluorane, 3-ethylamino-7-methylfluorane, 3- (N-ethyl-N-isoamyl) amino-benzo [a] fluorane, 3-n-dibutylamino-6-methyl- 7-Bromofluorane, 3,6-bis (diethylaminofluorane) -γ- (4'-nitro) anilinolactam,

Green dye precursors include 3- (N-ethyl-Nn-hexyl) amino-7-anilinofluorane and 3- (N-ethyl-N-p-tolyl) amino-7- (N). -Phenyl-N-methyl) aminofluorane, 3- (N-ethyl-N-n-propyl) amino-7-dibenzylaminofluorane, 3- (N-ethyl-N-n-propyl) amino-6 -Chloro-7-dibenzylaminofluorane, 3- (N-ethyl-N-4-methylphenyl) amino-7- (N-methyl-N-phenyl) aminofluorane, 3- (N-ethyl-4) -Methylphenyl) amino-7-dibenzylaminofluorane, 3- (N-ethyl-4-methylphenyl) amino-6-methyl-7-dibenzylaminofluorane, 3- (N-ethyl-4-methyl) Phenyl) amino-6-methyl-7- (N-methyl-N-benzyl) aminofluorane, 3- (N-methyl-Nn-hexyl) amino-7-anilinofluorane, 3- (N-) Propyl-Nn-hexyl) amino-7-anilinofluorane, 3- (N-ethoxy-Nn-hexyl) amino-7-anilinofluorane, 3- (Nn-pentyl-N-) Allyl) Amino-6-methyl-7-anilinofluorane, 3- (Nn-pentyl-N-allyl) amino-7-anilinofluorane, 3-di-n-butylamino-6-chloro- 7- (2-chloroanilino) fluorane, 3-di-n-butylamino-6-methyl-7- (2-chloroanilino) fluorane, 3-di-n-butylamino-6-methyl-7- (2-fluoro) Anilino) fluorane, 3-n-dibutylamino-7- (2-chloroanilino) fluorane, 3-di-n-butylamino-7- (2-chlorobenzylanilino) fluorane, 3,3-bis (4-) Diethylamino-2-ethoxyphenyl) -4-azaphthalide, 3,6-bis (dimethylamino) fluorene-9-spiro-3'-(6'-dimethylamino) phthalide, 3-diethylamino-6-methyl-7-benzyl Aminofluorane, 3-diethylamino-6-methyl-7-dibenzylaminofluorane, 3-diethylamino-6-methyl-7-n-octylaminofluorane, 3-diethylamino-6-methyl-7- (N-) Cyclohexyl-N-benzyl) aminofluorane, 3-diethylamino-6-methyl-7- (2-chloroanilino) fluorane, 3-diethylamino-6-methyl- 7- (2-Trifluoromethylanilino) fluorane, 3-diethylamino-6-methyl-7- (3-trifluoromethylanilino) fluorane, 3-diethylamino-6-methyl-7- (2-ethoxyanilino) ) Fluorane, 3-diethylamino-6-methyl-7- (4-ethoxyanilino) fluorane, 3-diethylamino-6-chloro-7- (2-chloroanilino) fluorane, 3-diethylamino-6-chloro-7-di Benzylaminofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3-diethylamino-6-ethylethoxy-7-anilinofluorane, 3-diethylamino-7-anilinofluorane, 3-diethylamino -7-Methylanilinofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3-diethylamino-7-n-octylaminofluorane, 3-diethylamino-7-p-chloroanilinofluorane, 3- Diethylamino-7-p-methylphenylanilinofluorane, 3-diethylamino-7- (N-cyclohexyl-N-benzyl) aminofluorane, 3-diethylamino-7- (2-chloroanilino) fluorane, 3-diethylamino-7 -(3-Trifluoromethylanilino) fluorane, 3-diethylamino-7- (2-trifluoromethylanilino) fluorane, 3-diethylamino-7- (2-ethoxyanilino) fluorane, 3-diethylamino-7- (4-ethoxyanilino) fluorane, 3-diethylamino-7- (2-chlorobenzylanilino) fluorane, 3-dimethylamino-6-chloro-7-dibenzylaminofluorane, 3-dimethylamino-6-methyl -7-n-octylaminofluorane, 3-dimethylamino-7-dibenzylaminofluorane, 3-dimethylamino-7-n-octylaminofluorane, 3-di-n-butylamino-7- (2) -Fluoroanilino) Fluoran, 3-anilino-7-dibenzylaminofluorane, 3-anilino-6-methyl-7-dibenzylaminofluorane, 3-pyrrolidino-7-dibenzylaminofluorane, 3-pyrrolidino -7- (4-Cyclohexylanilino) fluorane, 3-dibenzylamino-6-methyl-7-dibenzylaminofluorane, 3,7-bis (dibenzylamino) fluorane, 3-dibenzylamino-7- (2-Chloroanilino) Fluoran,

Blue dye precursors include 3- (1-ethyl-2-methylindole-3-yl) -3- (4-diethylaminophenyl) phthalide and 3- (1-ethyl-2-methylindole-3-). Il) -3- (2-Methyl-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3- (2-ethoxy-4-aminophenyl)- 4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3- (2-ethoxy-4-methylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole) -3-yl) -3- (2-ethoxy-4-ethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3- (2-ethoxy-4-yl) Dimethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-) 2-Methylindole-3-yl) -3- (2-ethoxy-4-di-n-propylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3 -(2-ethoxy-4-di-n-butylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3- (2-ethoxy-4-di-n) -Pentylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3- (2-ethoxy-4-di-n-hexylaminophenyl) -4-azaphthalide, 3 -(1-Ethyl-2-methylindole-3-yl) -3- (2-ethoxy-4-dihydroxyaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3- (2-ethoxy-4-dichloroaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3- (2-ethoxy-4-dibromoaminophenyl)- 4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3- (2-ethoxy-4-dialylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole) -3-Il) -3- (2-ethoxy-4-dimethoxyaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3-Il (2-ethoxy-4-diethoxyaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3- (2-ethoxy-4-dicyclohexylaminophenyl) -4- Azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3- (2-ethoxy-4-di-n-propoxyaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-) Methylindole-3-yl) -3- (2-ethoxy-4-di-n-butoxyaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3-( 2-ethoxy-4-di-n-hexyloxyaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3- (2-ethoxy-4-di-methylcyclohexyl) Aminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3- (2-ethoxy-4-di-methoxycyclohexylaminophenyl) -4-azaphthalide, 3- (1) -Ethyl-2-methylindole-3-yl) -3- (2-ethoxy-4-pyrrolidylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3 -(3-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3- (2,3-diethoxy-4-diethylaminophenyl) -4- Azaphthalide, 3- (1-ethyl-2-methylindole-3-yl)
-3- (4-Diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3- (2-chloro-4-diethylaminophenyl) -4-azaphthalide, 3- (1-Ethyl-2-methylindol-3-yl) -3- (3-Chloro-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3 -(2-Bromo-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3- (3-bromo-4-diethylaminophenyl) -4-azaphthalide, 3- (1-Ethyl-2-methylindol-3-yl) -3- (2-ethyl-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-n-propyl-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3- (3-methyl-4-diethylaminophenyl)- 4-Azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-nitro-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-) 3-Il) -3- (2-allyl-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3- (2-hydroxy-4-diethylaminophenyl) ) -4-Azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-cyano-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methyl) Indol-3-yl) -3- (2-cyclohexylethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3- (2-methylethoxy-) 4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-yl) -3- (2-cyclohexylethyl-4-diethylaminophenyl) -4-azaphthalide, 3- (2-) Ethylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-chloroindole-3-yl) -3- (2-ethoxy-4) -Diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl -2-Bromoindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-ethylindol-3-yl) -3- (2-) Ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-propylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1) -Ethyl-2-methoxyindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-ethoxyindole-3-yl) -3- ( 2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-phenylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-Ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3 -(2-Ethyl-4-diethylaminophenyl) -4,7-diazaphthalide, 3- (1-ethyl-4,5,6,7-tetrachloro-2-methylindol-3-yl) -3- (2) −ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-4-nitro-2-methylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide , 3- (1-Ethyl-4-methoxy-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-4-methylamino) -2-Methylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-4-methyl-2-methylindole-3-yl) -3 -(2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (2-methylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1) −Chloro-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-bromo-2-methylindol-3-yl) -3- ( 2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1) -Methyl-2-methylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-methyl-2-methylindole-3-yl) -3- ( 2-ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3- (1-n-propyl-2-methylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-n-butyl-2-methylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-n-butyl-2-indole-3) -Il) -3- (2-ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3- (1-n-pentyl-2-methylindole-3-yl) -3- (2-ethoxy-4-diethylamino) Phenyl) -4-azaphthalide, 3- (1-n-hexyl-2-methylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-n-) Hexyl-2-methylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3- (1-n-octyl-2-methylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-n-octyl-2-methylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -7-azaphthalide , 3- (1-n-octyl-2-methylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4,7-diazaphthalide, 3- (1-n-nonyl-2-) Methylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-methoxy-2-methylindole-3-yl) -3- (2-ethoxy-4) -Diethylaminophenyl) -4-azaphthalide, 3- (1-ethoxy-2-methylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-phenyl- 2-Methylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-n-pentyl-2-methylindole-3-yl) -3- (2) −ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3- (1-n-heptyl) -2-Methylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3- (1-n-nonyl-2-methylindole-3-yl) -3-( 2-ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3,3-bis (4-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-dimethylamino-2-methylphenyl) -3- (4-Dimethylaminophenyl) -6-dimethylaminophthalide, 3- (1-ethyl-2-methylindole-3-yl) -3- (4-diethylamino-2-n-hexyloxyphenyl) -4- Examples include azaphthalide. These can be used alone or in combination of two or more.

Some functional dye precursors have absorption in the near infrared region. When this dye precursor is used alone or in combination with other dye precursors as a dye precursor for high temperature color development, the high temperature color development image is automatically read in near infrared light with absorption in the near infrared region. Can be an image that can be used. When this dye precursor is used in the present invention, an image having absorption only in the visible region, an image having absorption in the near infrared region, and the like can be used in combination, and a highly secure recording material can be obtained.

Examples of such dye precursors having absorption in the near infrared region include 3,3-bis [1- (4-methoxyphenyl) -1- (4-dimethylaminophenyl) ethylene-2-yl] -4. , 5,6,7-Tetrachlorophthalide, 3,3-bis [1- (4-methoxyphenyl) -1- (4-pyrrolidinophenyl) ethylene-2-yl] -4,5,6,7 -Tetrachlorophthalide, 3,3-bis [1,1-bis (4-pyrrolidinophenyl) ethylene-2-yl] -4,5,6,7-tetrabromophthalide, 3- [1,1 -Bis (p-diethylaminophenyl) ethylene-2-yl] -6-dimethylaminophthalide, 3,6-bis (dimethylamino) fluorene-9-spiro-3'-(6'-dimethylamino) phthalide, 3 -[P- (p-dimethylaminoanilino) anilino] -6-methylfluorane, 3- [p- (p-dimethylaminoanilino) anilino] -6-methyl-7-chlorofluorine, 3-( pn-butylaminoanilino) -6-methyl-7-chlorofluorine, 3-[p-(p-anilinoanilino) anilino] -6-methyl-7-chlorofluorine, 3-[p-(p-) -Chloroanilino) Anilino] -6-methyl-7-chlorofluorane, 3- (Np-tolyl-N-ethylamino) -6,8,8-trimethyl-9-ethyl-8,9-dihydro- ( 3,2,e) pyridofluorane, 3-di (n-butyl) amino-6,8,8-trimethyl-8,9-dihydro- (3,2, e) pyridofluorane, 3'-phenyl-7-N- Examples thereof include diethylamino-2,2'-spirology (2H-1-benzopyran), bis (p-dimethylaminostyryl) -p-trisulfonylmethane, 3,7-bis (dimethylamino) -10-benzoylphenothiazine. These dye precursors may be used alone or in combination of two or more, if necessary.

In order to obtain sufficient thermal responsiveness, it is preferable that the total amount of the dye precursor accounts for 1 to 30% by mass in the total solid content of the thermal recording layer.

Examples of the color developer contained in the heat-sensitive recording layer in the present invention include the above-mentioned bis (3-allyl-4-hydroxyphenyl) sulfone and 3- (3-tosylureide) phenyl-p-toluenesulfonate, as well as the present invention. As long as the effect of the above is not impaired, a known pressure-sensitive recording material listed below or a color developer used in the heat-sensitive recording material can be contained, but the present invention is not particularly limited.

4,4'-Dihydroxydiphenylsulfone, 2,4′-dihydroxydiphenylsulfone, 4-hydroxy-4′-propoxydiphenylsulfone, 4-hydroxy-4′-isopropoxydiphenylsulfone, 4-hydroxy-4′-allyloxy Diphenylsulfone, 4-hydroxy-4'-octyloxydiphenylsulfone, 4-hydroxy-4′-dodecyloxydiphenylsulfone, 4-hydroxy-4′-benzyloxydiphenylsulfone, 3,4-dihydroxy-4′-methyldiphenyl Phenyl, 4-hydroxy-4'-benzenesulfonyloxydiphenylsulfone, 2,4-bis (phenylsulfonyl) phenol, p-phenylphenol, p-hydroxyacetophenone, 1,1-bis (p-hydroxyphenyl) propane, 1, , 1-bis (p-hydroxyphenyl) pentane, 1,1-bis (p-hydroxyphenyl) hexane, 1,1-bis (p-hydroxyphenyl) cyclohexane, 2,2-bis (p-hydroxyphenyl) propane , 2,2-bis (p-hydroxyphenyl) hexane, 1,1-bis (p-hydroxyphenyl) -2-ethylhexane, 2,2-bis (3-chloro-4-hydroxyphenyl) propane, 1, 1-bis (p-hydroxyphenyl) -1-phenylethane, 1,3-bis [2- (p-hydroxyphenyl) -2-propyl] benzene, 1,3-bis [2- (3,4-dihydroxy) Phenyl) -2-propyl] benzene, 1,4-bis [2- (p-hydroxyphenyl) -2-propyl] benzene, 4,4'-dihydroxydiphenyl ether, 3,3'-dichloro-4,4'- Dihydroxydiphenyl sulfide, methyl 2,2-bis (4-hydroxyphenyl) acetate, butyl 2,2-bis (4-hydroxyphenyl) acetate, 4- [4- (4- {4- [4- (isopropoxy)) Phenylsulfonyl] phenoxy} butoxy) phenylsulfonyl] phenol, 4,4'-[oxybis (ethyleneoxy-p-phenylenesulfonyl)] diphenol, 4,4'-thiobis (2-tert-butyl-5-methylphenol) , Dimethyl 4-hydroxyphthalate, benzyl 4-hydroxybenzoate, methyl 4-hydroxybenzoate, benzyl gallate, stearyl gallate, salicylanilide, 5-chlorosalitylanilide, salicylic acid, 3,5-di- tert-butyl salicylic acid, 3,5-bis (α-methylbenzyl) salicylic acid, 4- [2'-(4-methoxyphenoxy) ethyloxy] salicylic acid, 3- (octyloxycarbonylamino) salicylic acid or metal salts of these salicylic acid derivatives , N- (4-hydroxyphenyl) -p-toluenesulfonamide, N- (4-hydroxyphenyl) benzenesulfonamide, N- (4-hydroxyphenyl) -1-naphthalenesulfonamide, N- (4-hydroxyphenyl) ) -2-Naphthalene Sulfonamide, N- (4-Hydroxynaphthyl) -p-Toluene Sulfonamide, N- (4-Hydroxynaphthyl) benzene Sulfonamide, N- (4-Hydroxynaphthyl) -1-naphthalene Sulfonamide, N- (4-Hydroxynaphthyl) -2-naphthalenesulfonamide, N- (3-hydroxyphenyl) -p-toluenesulfonamide, N- (3-hydroxyphenyl) benzenesulfonamide, N- (3-hydroxyphenyl) -1-naphthalene sulfonamide, N- (3-hydroxyphenyl) -2-naphthalene sulfonamide, 4,4'-bis [(4-methyl-3-phenoxycarbonylaminophenyl) ureido] diphenylsulfonamide, N- [2 -(3-Phenylureid) phenyl] benzenesulfonamide, N-(2-{[(4-methylphenyl) carbamoyl] amino} phenyl) benzenesulfonamide, 4-methyl-N- {2-[(phenylcarbamoyl)) Amino] phenyl} benzenesulfonamide, 4-methyl-N- (2-{[(4-methylphenyl) carbamoyl] amino} phenyl) benzenesulfonamide, N-butylbutyl-4- [3- (p-toluenesulfonyl)) Ureido] benzoate, 3,3'-(4,4'-methylenediphenyl) bis (ureido p-trissulfonamide), bis {3- [3'-(p-toluenesulfonyl) ureido] benzoate}, 1,5- Examples thereof include (3-oxopentylene) bis {3'-[3'-(p-toluenesulfonyl) ureido] benzoate}, derivatives of N-phenylsulfonyl-N'-phenylurea, and the like, but are limited thereto. In addition, these color-developing agents may be used in combination of two or more as required.

In order to obtain sufficient thermal responsiveness, the total amount of the color developer in the total solid content of the thermal recording layer is preferably 10 to 500% by mass with respect to the dye precursor.

In the present invention, the heat-sensitive recording layer preferably contains various water-soluble polymer compounds or water-dispersible polymer compounds used in ordinary coating as binders for the dye precursor and the color developer described above. Specifically, cellulose derivatives such as starches, hydroxymethyl cellulose, hydroxypropyl cellulose, methyl cellulose, ethyl cellulose, and carboxymethyl cellulose, proteins such as gelatin and casein, fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, modified polyvinyl alcohol, and alginic acid. Soda, polyvinylpyrrolidone, polyacrylamide, acrylamide / acrylic acid ester copolymer, acrylamide / acrylic acid ester / methacrylic acid ternary copolymer, alkali salt of polyacrylic acid, alkali salt of polymaleic acid, styrene / maleic anhydride Water-soluble polymer compounds such as alkali salts of polymers, alkali salts of ethylene / maleic anhydride copolymers, alkali salts of isobutylene / maleic anhydride copolymers, and alkali salts of styrene / isobutylene / maleic anhydride copolymers. , And styrene / butadiene copolymer, acrylonitrile / butadiene copolymer, methyl acrylate / butadiene copolymer, acrylonitrile / butadiene / styrene ternary copolymer, polyvinyl acetate, vinyl acetate / acrylic acid ester copolymer, Ethylene / vinyl acetate copolymer, polyacrylic acid ester, polymethacrylic acid ester, styrene / acrylic acid ester copolymer, water-dispersible polymer compound such as polyurethane, acrylonitrile (core) / methacrylic acid (shell), acrylonitrile ( Examples thereof include water-dispersible polymer compounds having a core-shell structure such as core) / methacrylicamide / styrene copolymer (shell), but the present invention is not limited to these, and one or two may be used as necessary. It can contain more than a seed. The binder is preferably in the range of 5 to 45% by mass in the total solid content of the thermal recording layer. In particular, when the total amount of the binder is in the range of 20 to 30% by mass in the total solid content of the heat-sensitive recording layer, a heat-sensitive recording linerless label having excellent color development sensitivity and image storage stability after long-term storage can be obtained, which is preferable. When the heat-sensitive recording layer contains a water-dispersible acrylic resin typified by acrylonitrile (core) / methacrylamide (shell), polyacrylic acid ester, and polymethacrylic acid ester, and silanol-modified polyvinyl alcohol, the heat-sensitive recording layer is used. It is preferable because it improves the adhesion to the release layer containing the silicone resin.

In the present invention, the heat-sensitive recording layer can contain a low melting point heat-soluble component (hereinafter, referred to as a sensitizer) that promotes a color development reaction in order to further improve its heat responsiveness. In this case, the sensitizer is preferably a compound having a melting point of 60 to 180 ° C.

Specific examples of the sensitizer include fatty acid monoamides such as palmitic acid monoamide and stearic acid monoamide, diphenylsulfone, N-hydroxymethylstearic acid amide, N-stearylstearic acid amide, ethylenebisstearic acid amide, and methylenebissteer acid. Amide, methylol stearate amide, N-stearyl urea, benzyl-2-naphthyl ether, p-toluenesulfonamide, m-terphenyl, 4-benzylbiphenyl, 2,2'-bis (4-methoxyphenoxy) diethyl ether, α, α'-diphenoxy-o-xylene, bis (4-methoxyphenyl) ether, diphenyl adipate, dibenzyl oxalate, bis (4-methylbenzyl) oxalate ester, bis (4-chlorobenzyl) ester, dimethyl terephthalate , Dibenzyl terephthalate, benzenesulfonic acid phenyl ester, bis (4-allyloxyphenyl) sulfone, 1,2-bis (3-methylphenoxy) ethane, 1,2-diphenoxyethane, 4-acetylacetophenone, acetoacetate anilide Classes, fatty acid anilides, and other known sensitizers are listed, but the present invention is not limited thereto.

As a sensitizer, two or more of these compounds can be used in combination. Further, in order to obtain sufficient thermal responsiveness, it is preferable that the total amount of the sensitizer accounts for 3 to 50% by mass in the total solid content of the heat-sensitive recording layer.

In the present invention, the heat-sensitive recording layer can further contain a hindered phenol-based compound, a hindered amine-based compound, a phosphoric acid ester derivative, or a benzotriazole derivative, if necessary.

Specific examples of the hindered phenol-based compound contained in the heat-sensitive recording layer include 1,1,2,2-tetrakis (5-cyclohexyl-4-hydroxy-2-methylphenyl) ethane, 1,1,2, 2-Tetrax (3-phenyl-4-hydroxyphenyl) ethane, 1,1,2,2-tetrakis (3-tert-butyl-4-hydroxyphenyl) ethane, 1,1,3-Tris (3-cyclohexyl-) 4-Hydroxyphenyl) butane, 1,1,3-tris (5-cyclohexyl-4-hydroxy-2-methylphenyl) butane, 1,1,3-tris (3-cyclohexyl-4-hydroxy-5-methylphenyl) ) Butane, 1,1,3-tris (3-phenyl-4-hydroxyphenyl) butane, 1,1,3-tris (5-phenyl-4-hydroxy-2-methylphenyl) butane, 1,1,3 -Tris (3-tert-butyl-4-hydroxyphenyl) butane, 1,1,3-tris (5-tert-butyl-4-hydroxy-2-methylphenyl) butane, 1,1,3,3-tetrakis (5-Cyclohexyl-4-hydroxy-2-methylphenyl) propane, 1,1,3,3-tetrakis (3-cyclohexyl-4-hydroxyphenyl) propane, 1,1,5,5-tetrakis (5-cyclohexyl) -4-Hydroxy-2-methylphenyl) pentane, 1,1,3,3-tetrakis (3-cyclohexyl-4-hydroxyphenyl) pentane, 1,1,3,3-tetrakis (3-phenyl-4-hydroxy) Phenyl) propane, 1,1,3,3-tetrakis (5-phenyl-4-hydroxy-2-methylphenyl) propane, 1,1,3,3-tetrakis (3-tert-butyl-4-hydroxyphenyl) Propane, 1,1,3,3-tetrakis (5-tert-butyl-4-hydroxy-2-methylphenyl) propane, 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 2,2 ′ -Methylenebis (4-ethyl-6-tert-butylphenol), 2,2′-ethylidenebis (4,6-di-tert-butylphenol), 4,4′-thiobis (3-methyl-6-tert-butylphenol) ), 4,4'-thiobis (2-methyl-6-tert-butylphenol), 4,4'-thiobis (2-methylphenol), 4,4'-thiobis (2,6-dimethylphenol), 4, 4' -Thiobis (2,6-di-tert-butylphenol), 2,2'-thiobis (4-tert-octylphenol), 2,2'-thiobis (3-tert-octylphenol), 4,4'-butylidenebis (6) -Tert-Butyl-m-cresol), 1- [α-methyl-α- (4'-hydroxyphenyl) ethyl] -4- [α', α'-bis (4 "-hydroxyphenyl) ethyl] benzene, Examples include, but are limited to, 2,2-bis (4-hydroxy-3,5-dibromophenyl) propane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, and the like. In addition, these compounds may be used alone or in combination of two or more, if necessary.

Specific examples of the hindered amine compound contained in the heat-sensitive recording layer include bis (2,2,6,6, -tetramethyl-4-piperidyl) sebacate and succinate-bis (2,2,6,6). -Tetramethyl-4-piperidyl) ester, butane-1,2,3,4-tetracarboxylic acid-tetrakis [1,2,2,6,6-pentamethyl (4-piperidyl)] ester, butane-1,2 , 3,4-Tetracarboxylic acid-tetrakis [2,2,6,6-tetramethyl (4-piperidyl)] ester and the like, but are not limited to these, and compounds thereof. Can be used alone or in combination of two or more as needed.

Specific examples of the phosphate ester derivative contained in the heat-sensitive recording layer include triphenyl phosphate, diphenyl phosphate, bis (4-tert-butylphenyl) phosphate, and bis (4,6-di-tert-butylphenyl) phosphate. , Bis (4-chlorophenyl) phosphate, bis (benzyloxyphenyl) phosphate, 2,2'-methylenebis (4,6-di-tert-butylphenyl) phosphate, dimethyloxyphosphate, diethyloxyphosphate, bis (3,5) -Di-tert-butyl-4-hydroxyphenyl) phosphate, 3,5-di-tert-butyldiphenyl phosphate, diethyl (3,5-di-tert-butyl-4-hydroxyphenyl) phosphate, and 2,2'. Sodium salt of −methylenebis (4,6-di-tert-butylphenyl) phosphate, calcium salt of 2,2′-methylenebis (4,6-di-tert-butylphenyl) phosphate, 2,2′-methylenebis (4) , 6-Di-tert-butylphenyl) phosphate zinc salt, 2,2′-methylenebis (4,6-di-tert-butylphenyl) phosphate ammonium salt, potassium salt and the like. In addition, these compounds may be used alone or in combination of two or more, if necessary.

Specific examples of the benzotriazole derivative contained in the heat-sensitive recording layer include 2- (2-hydroxyphenyl) benzotriazole, 2- (2-hydroxy-5-methylphenyl) benzotriazole, 2- (2-hydroxy-). 5-tert-butylphenyl) benzotriazole, 2- (2-hydroxy-3,5-di-tert-butylphenyl) benzotriazole, 2- (2-hydroxy-3-tert-butyl-5-methylphenyl)- 5-Chlorobenzotriazole, 2- (2-hydroxy-3,5-di-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2-hydroxy-3,5-di-tert-aminophenyl) benzo Triazole, 2- (2-hydroxy-3,5-di-tert-butylphenyl) -5-tert-butylbenzotriazole, 2- (2-hydroxy-3-dodecyl-5-methylphenyl) benzotriazole, 2- [2-Hydroxy-4- (2-ethylhexyl) oxyphenyl] Benzotriazole, methyl-3- (3-tert-butyl-5-benzotriazolyl-4-hydroxyphenyl) propionate-polyethylene glycol (molecular weight: about 300) Condensate with, 5-tert-butyl-3- (5-chloro-benzotriazolyl) -4-hydroxybenzene-octyl propionate, 2- (2-hydroxy-3-sec-butyl-5-tert- Butylphenyl) -5-tert-butylbenzotriazole, 2- (2-hydroxy-4-methoxy-5-sulfophenyl) benzotriazole sodium salt, 2- (2-hydroxy-4-butoxy-5-sulfophenyl) benzo Triazole sodium salt, 2,2'-methylenebis (4-methyl-6-benzotriazolylphenol), 2,2'-methylenebis [4-methyl-6- (5-methylbenzotriazolyl) phenol], 2 , 2'-Methylenebis [4-methyl-6- (5-chlorobenzotriazolyl) phenol], 2,2'-Methylenebis [4- (1,1,3,3-tetramethylbutyl) -6-benzo Triazolylphenol], 2,2'-methylenebis (4-tert-butyl-6-benzotriazolylphenol), 2,2'-propyridenebis (4-methyl-6-benzotriazolylphenol), 2, 2'-isopropyridenebis (4-methyl-6-benzotriazolylphenol), 2, 2'-isopropylidenebis [4- (1,1,3,3-tetramethylbutyl) -6-benzotriazolylphenol], 2,2'-octylidenebis [4-methyl-6- (5-methylbenzo) (Triazolyl) phenol] and the like, but the present invention is not limited to this, and one or more of these compounds may be used as required.

In the present invention, the total content of the hindered phenolic compound or hindered amine compound, the phosphate ester derivative, or the benzotriazole derivative used in the heat-sensitive recording layer described above is 5 with respect to the dye precursor. ~ 100% by mass is a preferable range, and a more preferable range is 10 to 80% by mass.

In the present invention, the heat-sensitive recording layer can contain various pigments for the purpose of improving sticking resistance, improving whiteness, and the like. For example, siliceous soil, talc, kaolin, calcined kaolin, calcium carbonate, magnesium carbonate, aluminum hydroxide, magnesium hydroxide, titanium dioxide, zinc oxide, silicon oxide, amorphous silica, amorphous calcium silicate, colloidal silica, colloidal. Known pigments such as white inorganic pigments such as alumina, calcium sulfate, barium sulfate, zinc sulfide, zinc carbonate, satin white, aluminum silicate, calcium silicate, magnesium silicate, alumina, lithopon, zeolite, and hydrohaloicite can be mentioned.

In addition, the heat-sensitive recording layer uses waxes such as fatty acid metal salts, paraffin, paraffin oxide, polyethylene, polyethylene oxide, and caster wax to improve sticking resistance, and various hardeners and cross-linking agents to provide water resistance. Can contain a dispersant such as sodium dioctyl sulfosuccinate, a surfactant, a fluorescent dye, a coloring dye, a brewing agent, an antifoaming agent and the like.

In the present invention, various color-developing components contained in the heat-sensitive recording layer are applied and dried on a support or an undercoat layer as a dispersion liquid dispersed in a dispersion medium. The dispersion can be obtained by a method of dry pulverizing a compound constituting a color-developing component and dispersing it in a dispersion medium, or a method of mixing a compound constituting a color-developing component with a dispersion medium and wet-pulverizing the compound. In the present invention, the color developer and the sensitizer are used alone or together with water as a dispersion medium, and the volume average particle diameter is adjusted together with the dispersant by various wet grinders such as a sand grinder, a ball mill, an attritor, and a bead mill. It is preferable that the particles are pulverized to 0.1 to 5.0 μm and then used for preparing a heat-sensitive recording layer coating liquid. As the dye precursor, water is used as a dispersion medium separately from the color developer, and the volume average particle size is preferably 0.1 to 1 together with the dispersant by various wet grinders such as a sand grinder, a ball mill, an attritor, and a bead mill. It is preferable that it is used for preparing a heat-sensitive recording layer coating liquid after being pulverized to 5.0 μm into fine particles.

In the present invention, the dispersant used when dispersing the compound constituting the color-developing component contained in the heat-sensitive recording layer includes fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, sulfonic acid-modified polyvinyl alcohol, silanol-modified polyvinyl alcohol, and carboxyl. Polyvinyl alcohols such as modified polyvinyl alcohol, diacetone-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, phosphate-modified polyvinyl alcohol, butyral-modified polyvinyl alcohol, epoxy-modified polyvinyl alcohol, starch or derivatives thereof, hydroxyethyl cellulose, methyl cellulose, hydroxypropyl cellulose, Cellulous derivatives such as ethyl cellulose and carboxymethyl cellulose, proteins such as gelatin and casein, acid neutralized products of chitosan, sodium alginate, polyvinylpyrrolidone, diisobutylene / maleic anhydride copolymer salt, styrene / isobutylene / maleic anhydride copolymer Water-soluble polymer compounds such as salt, styrene / maleic anhydride copolymer salt, ethylene / acrylic acid copolymer salt, styrene / acrylic acid copolymer salt, polyacrylic acid salt, polyacrylic sulfonate, dodecylbenzene Examples thereof include anionic low molecular weight surfactants such as sulfonates, dialkyl sulfosuccinates, alkylnaphthalene sulfonates, alkyldiphenyl ether disulfonates and fatty acid metal salts, and nonionic surfactants such as acetylene glycol. It is not limited to, and one kind or two or more kinds can be used as needed. The dispersant is preferably 0.5 to 30% by mass with respect to various color-developing components.

When crushing the color-developing component contained in the above-mentioned heat-sensitive recording layer, magnesium silicate, calcium silicate, magnesium carbonate, calcium carbonate, calcium sulfate, magnesium phosphate, magnesium oxide, aluminum oxide, titanium oxide, magnesium hydroxide, aluminum hydroxide , Kaolin, talcite, hydrotalcite and other inorganic pigments may be pulverized. Further, the dispersion liquid after pulverizing various color-developing components may be heated in the range of 40 to 80 ° C., or a coating layer formed of an organic polymer compound may be provided on the surface of the pulverized particles. good.

In the present invention, the forming method for forming the heat-sensitive recording layer on one surface of the support is not particularly limited, and can be formed by using a well-known technique. For example, a coating device such as an air knife coater, various blade coaters, various bar coaters, various curtain coaters, and various roll coaters, and various printing methods such as planographic, letterpress, intaglio, flexo, gravure, and screen can be used. Further, in order to improve the surface smoothness, various known techniques in the production of thermal recording materials can be used, such as the use of devices such as a machine calendar, a super calendar, a gloss calendar, and brushing. Further, curl correction can be performed by injecting water vapor with a humidifier such as Fludex to the other surface of the support having the heat-sensitive recording layer, or by applying and drying water.

Further, in the present invention, it is preferable to have an undercoat layer between the support and the heat-sensitive recording layer for the purpose of improving the color development sensitivity. The undercoat layer can contain a binder, various inorganic and organic pigments, hollow particles, foamed particles and the like. Examples of other components contained in the undercoat layer include known surfactants, coloring dyes, fluorescent dyes, lubricants, ultraviolet absorbers, defoamers and the like.

Examples of the pigment contained in the undercoat layer in the present invention include talc, kaolin, calcined kaolin, heavy calcium carbonate, light calcium carbonate, magnesium carbonate, zinc oxide, aluminum oxide, aluminum hydroxide, magnesium hydroxide, and titanium dioxide. , Inorganic pigments such as barium sulfate, zinc sulfate, amorphous silica, calcium silicate, colloidal silica, organic pigments such as melamine resin, urea-formaldehyde resin, polyethylene, polystyrene, ethylene-vinyl acetate, etc. It can be contained in combination of two or more. In order to obtain sufficient color development, the content of the pigment in the undercoat layer is preferably 20% by mass or more with respect to the total solid amount of the undercoat layer.

In the present invention, the hollow particles contained in the undercoat layer are microspherical hollow particles having a thermoplastic resin as a shell and containing air and other gases inside, and preferably have an average particle diameter of 0.1 to 10 μm. .. If the average particle size (outer particle size) is smaller than 0.1 μm, production problems such as difficulty in controlling the hollow ratio may occur. Conversely, if the average particle size is larger than 10 μm, the surface after coating and drying may occur. Since the smoothness of the particles is lowered, the adhesion to the thermal head is lowered and the effect of improving the color development sensitivity may be lowered. Such hollow particles preferably have a hollow ratio of 40% or more. For example, Dow Chemical Japan Co., Ltd. sells Low Pake (registered trademark) SN-1055, Nippon Zeon Corporation sells Nipol (registered trademark) MH8055, and the like. It is available and can be obtained. The hollow ratio referred to here is a value obtained by dividing the volume of the hollow portion of the hollow resin by the volume of the hollow particles. In the present invention, the content of hollow particles in the undercoat layer is preferably 20% by mass or more with respect to the total solid amount of the undercoat layer.

As the binder contained in the undercoat layer, various water-soluble polymer compounds or water-dispersible polymer compounds used in ordinary coating can be contained. Specific examples thereof include starches, hydroxymethyl cellulose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, gelatin, casein, fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, modified polyvinyl alcohol, sodium alginate, polyvinylpyrrolidone, polyacrylamide, and the like. Acrylamide / acrylic acid ester copolymer, acrylamide / acrylic acid ester / methacrylic acid ternary copolymer, alkali salt of polyacrylic acid, alkali salt of polymaleic acid, alkali salt of styrene / maleic anhydride copolymer, ethylene / Water-soluble polymer compounds such as alkali salts of maleic anhydride copolymers, alkali salts of isobutylene / maleic anhydride copolymers, alkali salts of styrene / isobutylene / maleic anhydride copolymers, urethane resins, styrene / butadiene Copolymer, Acrylonitrile / butadiene copolymer, Methyl acrylate / butadiene copolymer, Acrylonitrile / butadiene / styrene ternary copolymer, Polyvinyl acetate, Vinyl acetate / Acrylic acid ester copolymer, Ethylene / Vinyl acetate Examples thereof include, but are not limited to, water-dispersible polymer compounds such as polymers, polyacrylic acid esters, and styrene / acrylic acid ester copolymers. The binder may contain one kind or two or more kinds. The binder is preferably contained in the range of 10 to 30% by mass in the total solid content of the undercoat layer.

In the present invention, the undercoat layer is coated on a support with a coating liquid for the undercoat layer prepared by mixing and stirring a pigment and, if necessary, a binder and an auxiliary agent using water or the like as a medium, and drying the undercoat layer. It is preferably formed.

In the present invention, when various components contained in the undercoat layer are mixed and stirred using water or the like as a medium, a dispersant can be used to improve the dispersibility. Dispersants used include polyvinyl alcohols such as fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, and modified polyvinyl alcohol, starch or derivatives thereof, and cellulose derivatives such as hydroxyethyl cellulose, methyl cellulose, hydroxypropyl cellulose, ethyl cellulose, and carboxymethyl cellulose. , Gelatin, proteins such as casein, acid neutralized products of chitosan, sodium alginate, polyvinylpyrrolidone, diisobutylene / maleic anhydride copolymer salt, styrene / isobutylene / maleic anhydride copolymer salt, styrene / maleic anhydride Water-soluble polymer compounds such as polymer salt, ethylene / acrylic acid copolymer salt, styrene / acrylic acid copolymer salt, polyacrylic acid salt, polyacrylic sulfonate, dodecylbenzene sulfonate, dialkyl sulfosuccinate , Alkylnaphthalene sulfonate, alkyldiphenyl ether disulfonate, anionic low molecular weight surfactants such as fatty acid metal salts, nonionic surfactants typified by acetylene glycol, sodium hexametaphosphate and the like, but are limited thereto. However, one type or two or more types can be used as required. The dispersant is preferably 0.1 to 30% by mass with respect to various components.

The above-mentioned undercoat layer can be used, for example, by a coating device such as an air knife coater, various blade coaters, various bar coaters, various curtain coaters, various roll coaters, and various printing methods such as planographic, letterpress, intaglio, flexo, gravure, and screen. Etc. can be formed. Further, in order to improve the surface smoothness, devices such as a machine calendar, a super calendar, a gloss calendar, and a brushing can be used.

In the present invention, the release layer laminated on the above-mentioned heat-sensitive recording layer without a protective layer contains an ultraviolet curable silicone resin. By containing the ultraviolet curable silicone resin, it is possible to obtain a heat-sensitive recording linerless label having excellent color development sensitivity and image storage stability after long-term storage.

Silicone resins that form the release layer include solvent-based (thermosetting addition method, thermosetting condensation method), emulsion-based (thermosetting addition method, thermosetting condensation method), and solvent-free (thermosetting addition). (Method, UV curable type, electron beam curable type) are known, but as described above, in the present invention, a UV curable (solvent-free) silicone resin is used. Compared with thermosetting addition type silicone resin and thermosetting type condensation type silicone resin, the ultraviolet curable silicone resin has a smaller temperature rise of the base material (heat sensitive recording material), so that the heat sensitive recording linerless label has less background fog. Is preferable because Further, the ultraviolet curable silicone resin is preferable because a heat-sensitive recording linerless label having a smaller peeling force between the peeling layer and the pressure-sensitive adhesive layer can be obtained as compared with the electron beam-curable silicone resin. Further, the ultraviolet curable silicone resin includes a radical addition method, a radical polymerization method, and a cationic polymerization method. However, the ultraviolet curable silicone resin cured by the radical addition method or the radical polymerization method is different from the cationic polymerization method in that it is a base material. Since it is not easily affected by the curing inhibitory component contained in (heat-sensitive recording material), curing is likely to occur in a short time, and a heat-sensitive recording linerless label having excellent color development sensitivity and long-term storage stability can be obtained, which is preferable. The radical polymerization method is particularly preferable because it does not have a pungent odor derived from the mercapto group-containing compound.

The ultraviolet curable silicone resin cured by the above-mentioned radical addition method, radical polymerization method, or cationic polymerization method is not particularly limited, and various ones can be used. Specifically, it has the following functional groups. Organopolysiloxane compound (polydimethylsiloxane, partial or all of the methyl group of polydimethylsiloxane is replaced with an aliphatic functional group other than the methyl group, an aliphatic functional group such as an alkenyl group or an alkynyl group, or an aromatic functional group such as a phenyl group. Can be preferably used. Examples of the ultraviolet curable silicone resin cured by the radical addition method include compounds having an organopolysiloxane structure containing an organopolysiloxane having a vinyl group as a functional group in the molecule as a base polymer and containing a mercapto group, and radical polymerization. Examples of the ultraviolet curable silicone resin cured by the method include an organopolysiloxane compound containing an acrylic group and / or a methacryl group as a functional group in the molecule, and examples of the ultraviolet curable silicone resin cured by the cationic polymerization method include an organopolysiloxane compound. Examples thereof include an organopolysiloxane compound containing an epoxy group as a functional group in the molecule. Commercially available products such as these can be used as ultraviolet curable silicone resins. For example, UV curable silicone resins that are cured by a radical addition method include BY24-551A and BY24-551B from Toray Dow Corning Co., Ltd. As an ultraviolet curable silicone resin that can be cured by a radical polymerization method, TEGO (registered trademark) RC902, TEGO RC715, etc. from Ebonic Japan Co., Ltd., and Arakawa Chemical Industry (Arakawa Chemical Industry Co., Ltd.) It is also possible to obtain and use commercially available products such as Siliconice (registered trademark) UV POLY201 and Siliconice UV POLY200 from Co., Ltd.

The release layer coating liquid may contain silicone resins other than ultraviolet curable (solvent-free) silicone resins, photopolymerization initiators, cross-linking agents, dyes, pigments, wetting agents, defoaming agents, dispersants, as necessary. Various auxiliaries such as antistatic agents, leveling agents, and lubricants can be contained. The Beck smoothness on the surface of the release layer is preferably 300 to 15,000 seconds. As a result, a heat-sensitive recording linerless label having excellent print quality (less white spots on the printed portion) can be obtained.

As a coating method of the release layer coating liquid, coating is performed by a normal coating machine, for example, a bar coater, a multi-stage roll coater, an air knife coater, a direct gravure coater, an offset gravure coater, a roll applicator, a curtain coater, or the like. Can be done. The amount of the release layer coating liquid applied is preferably 0.2 to 3.0 g / m ^{2 in} terms of the amount of solid content applied. If the solid content coating amount is less than 0.2 g / m ² , the effect as a peeling layer may be poor, and if it exceeds 3.0 g / m ² , the color development sensitivity may be lowered. Further, as an ultraviolet irradiation device for curing the release layer coating liquid, a plurality of lamps having an output of 30 W / cm or more are generally used in parallel. When irradiating with ultraviolet rays, if the oxygen concentration is high, the curing of the ultraviolet curable resin may be hindered. Therefore, the oxygen concentration was suppressed to 500 ppm or less by substituting with an inert gas such as nitrogen or helium or carbon dioxide. It is preferable to irradiate in an atmosphere. Furthermore, in order to suppress the penetration of substances that inhibit the color development of the heat-sensitive recording layer, such as silicone resin, into the heat-sensitive recording layer, after applying the release layer coating liquid, it is cured by irradiating with ultraviolet rays within 1 second. It is preferable to let it.

The pressure-sensitive adhesive layer on the other side of the support in the present invention contains a hot-melt pressure-sensitive adhesive.

In the present invention, when the pressure-sensitive adhesive layer contains a hot-melt pressure-sensitive adhesive, a heat-sensitive recording linerless label having excellent image storage stability after long-term storage can be obtained. The reason is presumed as follows.

In the prior art, for example, in Patent Document 1, for example, an acrylic emulsion adhesive is applied and dried (heat is applied) to form an adhesive layer, but in such a method, after long-term storage. The image sometimes faded. It is presumed that this is because it takes time for the acrylic emulsion pressure-sensitive adhesive to solidify and form the pressure-sensitive adhesive layer, so that some of the components of the coating liquid containing the acrylic emulsion pressure-sensitive adhesive are transferred to the heat-sensitive recording layer. However, when the pressure-sensitive adhesive layer is formed by using the pressure-sensitive adhesive layer coating liquid containing a hot-melt pressure-sensitive adhesive, the pressure-sensitive adhesive layer after coating is rapidly cooled to form a layer in a short time. The transfer of the components contained in is rapidly restricted, and as a result, it is presumed that the image preservation property after long-term storage is excellent.

As the hot melt adhesive used in the present invention, a rubber-based hot melt adhesive is preferable from the viewpoint of peelability to a silicone resin, stability of adhesive force, and bleeding, but the present invention is not limited to this, and ethylene-. A vinyl acetate copolymer, an ethylene-acrylic acid copolymer and the like may be used.

Examples of the rubber-based hot melt pressure-sensitive adhesive include styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-butadiene-styrene block copolymer (SBS), and styrene-isoprene-styrene block copolymer (Styrene-isoprene-styrene block copolymer). SIS), styrene-ethylene-propylene-styrene block copolymer (SEPS) and other styrene-based copolymer-containing pressure-sensitive adhesives can be mentioned, but the present invention is not limited thereto, and if necessary. One type or two or more types can be used. Commercially available hot melt adhesives such as these can be used. For example, commercially available products under product names such as JM-6197 and JM-6189ZP can be obtained and used from Sekisui Fuller Co., Ltd. Is.

The pressure-sensitive adhesive layer coating liquid containing the hot-melt pressure-sensitive adhesive in the present invention contains, in addition to the above-mentioned components, various pressure-sensitive adhesives, softeners, waxes, etc. for the purpose of improving adhesiveness and coating suitability. Can be done. Examples of the tackifier include aliphatic (C5) -based petroleum resin, aromatic (C9) -based petroleum resin, copolymer (C5 / C9) -based petroleum resin, dicyclopentadiene (DCPD) -based petroleum resin, and kumaron inden. Examples thereof include resins, acrylic resins, styrene resins, rosins, rosin ester resins, terpene resins, aromatic-modified terpene resins, terpene phenol resins, and hydrogenated resins thereof. Examples of softeners include various softeners. Examples thereof include plasticizers, polybutenes, liquid tackifier resins, polyisobutylene low polymers, polyvinylisobutyl ether low polymers, rosin, lump polymer rubber, process oils, naphthenic oils, paraffin oils, vulture oils, mineral oils, etc. Examples of waxes include vegetable waxes, animal waxes, mineral waxes, petroleum waxes, mineral waxes, synthetic waxes, and processed / modified waxes thereof.

The viscosity of the pressure-sensitive adhesive layer coating liquid containing the hot-melt pressure-sensitive adhesive in the present invention is preferably 1000 to 10000 mPa · s from the viewpoint of coatability. If the viscosity value is less than 1000 mPa · s or more than 10000 mPa · s, the coating film surface becomes non-uniform, which may affect the adhesive properties. The softening point measured by JIS K-6863 (1994) of the hot melt adhesive is preferably 80 to 150 ° C., and the melting temperature of the pressure-sensitive adhesive layer coating liquid containing the hot melt adhesive is 200 ° C. The following is preferable. If the melting temperature exceeds 200 ° C., the heat-sensitive recording material may cause a background fog when the pressure-sensitive adhesive layer coating liquid containing the hot-melt adhesive is applied. The lower limit is preferably 80 ° C. or higher. Further, after applying the adhesive layer coating liquid, cooling by a cooling roll or blowing air may be performed.

In the present invention, the pressure-sensitive adhesive layer coating liquid containing a hot-melt adhesive can be applied by a bar coater method, a roll coater method, a comma coater method, a gravure coater method, a slot die method, a curtain coater method, or the like. .. Further, if the coating amount (solid content) of the pressure-sensitive adhesive layer coating liquid containing the hot-melt adhesive is 10 to 25 g / m ² , stable adhesion is achieved regardless of the surface shape of the adherend to which the label is attached. It is preferable because it can obtain force. If the coating amount is less than 10 g / m ² , the surface of the corrugated cardboard cannot be covered with the adhesive on a rough surface such as corrugated cardboard, so that the adhesive strength may decrease. Further, if the coating amount exceeds 25 g / m ² , problems such as squeeze out of glue may occur when the roll shape is formed as the final form.

The present invention will be described below with reference to examples, but the present invention is not limited to these examples. In the examples, unless otherwise specified,% and parts are all based on mass. The coating amount is the absolute dry coating amount.

Example 1
(1) Preparation of Undercoat Layer Coating Solution The following formulations were mixed and sufficiently stirred to obtain an undercoat layer coating solution.
200 parts of 20% plastic hollow particle dispersion (manufactured by Dow Chemical Japan Co., Ltd., low pake SN-1055 (particle diameter 1 μm, hollow ratio 55%) diluted with water)
Calcined kaolin (BASF, Ansilex (registered trademark)) 60 parts 10% sodium hexametaphosphate aqueous solution 3 parts 10% ammonia water 1 part 20% urea-modified phosphoric acid esterified starch aqueous solution 25 parts (manufactured by Nippon Shokuhin Kako Co., Ltd.) , MS4600 dissolved in water)
37.5 parts of an aqueous dispersion of 40% styrene / butadiene copolymer (manufactured by Asahi Kasei Chemicals Co., Ltd., E1585 diluted with water)
13.5 parts of water

(2) Formation of Undercoat Layer The undercoat layer coating liquid prepared in (1) above is prepared from a neutral woodfree paper (support) having a width of 400 mm, a length of 10,000 m, and a basis weight of 60 g / m ² . An undercoat layer was formed on one surface by applying a rod coating method so that the solid content coating amount was 10 g / m ² and drying.

(3) Preparation of Dye Precursor Dispersion Solution The following formulations are mixed, wet-ground with a bead mill until the volume average particle size becomes 0.7 μm, and then heated at 70 ° C. for 30 minutes to perform a dye precursor. A dispersion was obtained.
3-Di-n-pentylamino-6-methyl-7-anilinofluorane 30 parts 10% sulfonic acid-modified polyvinyl alcohol aqueous solution 30 parts (Nippon Synthetic Chem Industry Co., Ltd., Gosenex (registered trademark) L-3266 Dissolved in water)
0.15 parts of acetylene dialcohol composition (manufactured by Air Products Japan Co., Ltd., Surfinol (registered trademark) 104E)
39.85 parts of water

(4) Preparation of color developer / sensitizer dispersion The following formulations are mixed and wet-ground with a bead mill until the volume average particle size becomes 0.7 μm to obtain a color developer / sensitizer dispersion. It was.
Bis (3-allyl-4-hydroxyphenyl) sulfone 60 parts 1,2-bis (3-methylphenoxy) ethane 40 parts 10% sulfonic acid-modified polyvinyl alcohol aqueous solution 100 parts (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., Gosenex L) -3266 dissolved in water)
0.5 parts of acetylene dialcohol composition (manufactured by Air Products Japan Co., Ltd., Surfinol 104E)
164.5 parts of water

(5) Preparation of Pigment Dispersion Solution for Thermal Recording Layer The following formulation was mixed and stirred to obtain a pigment dispersion solution for the thermal recording layer.
65 parts of light calcium carbonate (manufactured by Okutama Kogyo Co., Ltd., Tamapearl (registered trademark) TP-123)
7 parts of 10% aqueous ammonium polyacrylate solution (manufactured by GOO CHEMICAL CO., LTD., Microsol KE-511 diluted with water)
148 parts of water

(6) Preparation of Thermal Recording Layer Coating Liquid The following formulations were mixed and sufficiently stirred to obtain a thermal recording layer coating liquid.
Dye precursor dispersion 100 parts Color developer / sensitizer dispersion 365 parts Pigment dispersion for heat-sensitive recording layer 220 parts 10% silanol-modified polyvinyl alcohol aqueous solution 350 parts Kuraray Co., Ltd., 25-98R (R-1130) ) Dissolved in water)
350 parts of 10% core-shell acrylic resin (manufactured by Mitsui Chemicals, Inc., BM-1000 diluted with water)
150 parts of 20% zinc stearate aqueous dispersion (manufactured by Chukyo Yushi Co., Ltd., hydrin (registered trademark) L-536 diluted with water)

(7) Preparation of heat-sensitive recording material On the undercoat layer prepared in (2) above, the heat-sensitive recording layer coating liquid prepared in (6) above is applied so that the solid content coating amount is 5.0 g / m ^2. Then, it was coated and dried by the air knife coating method, and further subjected to calendar processing using a super calendar to prepare a heat-sensitive recording material. The Beck smoothness on the surface of the heat-sensitive recording layer after the calendering process was 300 seconds.

(8) Preparation of release layer coating solution 1 The following formulations were mixed to obtain a release layer coating solution (radical polymerization method).
30 parts of silicone resin containing acrylic group and / or methacrylic group (manufactured by Evonik Japan Co., Ltd., TEGO RC902)
30 parts of acrylate (TEGO RC1717 manufactured by Evonik Japan Co., Ltd.)
20 parts of silicon acrylate (TEGO RC1772, manufactured by Evonik Japan Co., Ltd.)
Photopolymerization initiator 2 parts (manufactured by Evonik Japan Co., Ltd., TEGO A-18)

(9) Preparation of a heat-sensitive recording material having a release layer On the heat-sensitive recording layer of the heat-sensitive recording material prepared in (7) above, the release layer coating liquid 1 prepared in (8) above is applied with a solid content coating amount of 1. It was coated by the gravure coating method so as to be .5 g / m ² . Within 1 second after coating the release layer coating solution, the release layer coating solution is cured by irradiating with ultraviolet rays using a UV lamp (120 W / cm × 2) in a nitrogen gas atmosphere (oxygen concentration 50 ppm or less). , A release layer was formed to prepare a heat-sensitive recording material having the release layer. The Beck smoothness on the surface of the release layer was 1000 seconds.

(10) Preparation of Thermal Recording Linerless Label A hot melt adhesive (manufactured by Sekisui Fuller Co., Ltd., manufactured by Sekisui Fuller Co., Ltd., is used on the surface of the thermal recording material having the release layer prepared in (9) above, which is opposite to the surface having the thermal recording layer. JM-6197, softening point 106 ° C) is heated and melted at 160 ° C (viscosity value 9500 mPa · s), then coated by the slot die method so that the solid content coating amount is 20 g / m ^2, and cooled to make an adhesive. The heat-sensitive recording linerless label of Example 1 was obtained by forming a layer, laminating the release layer and the pressure-sensitive adhesive layer, and winding them in a roll shape.

Example 2
In the preparation of the (4) color developer / sensitizer dispersion liquid of Example 1, bis (3-allyl-4-hydroxyphenyl) sulfone and 3- (3-tosylureide) phenyl-p-toluenesulfonate (BASF) were used. A heat-sensitive recording linerless label of Example 2 was produced in the same manner as in Example 1 except that the label was changed to PERGAFAST (registered trademark) 201) manufactured by the same company.

Example 3
In the production of the (10) thermal recording linerless label of Example 1, a hot melt adhesive (manufactured by Sekisui Fuller Co., Ltd., JM-6197) was used as a hot melt adhesive (manufactured by Sekisui Fuller Co., Ltd., JM-6189ZP, The heat-sensitive recording linerless label of Example 3 was produced in the same manner as in Example 1 except that the softening point was changed to 100 ° C.). The viscosity value of the hot melt adhesive at the time of heating and melting was 6000 mPa · s.

Example 4
In the preparation of (8) release layer coating solution 1 of Example 1, the same procedure as in Example 1 was carried out except that the release layer coating solution 1 was changed to the following release layer coating solution 2 (cationic polymerization method). The heat-sensitive recording linerless label of Example 4 was prepared. The Beck smoothness on the surface of the release layer was 1000 seconds.

(8) Preparation of release layer coating liquid 2 100 parts of epoxy group-containing silicone resin (Silicoleus UV POLY201 manufactured by Arakawa Chemical Industry Co., Ltd.)
Curing catalyst 5 parts (Silicollies CATA211 manufactured by Arakawa Chemical Industry Co., Ltd.)

Example 5
In the preparation of (8) release layer coating solution 1 of Example 1, the same procedure as in Example 1 was carried out except that the release layer coating solution 1 was changed to the following release layer coating solution 3 (radical addition method). The heat-sensitive recording linerless label of Example 5 was prepared. The Beck smoothness on the surface of the release layer was 1000 seconds. The completed heat-sensitive recording linerless label of Example 5 had a slightly pungent odor.

(8) Preparation of release layer coating liquid 3 100 parts of mercapto group-containing silicone resin (BY24-551A manufactured by Toray Dow Corning Co., Ltd.)
30 parts of vinyl group-containing silicone resin (BY24-551B manufactured by Toray Dow Corning Co., Ltd.)

Comparative Example 1
Example 1 except that the bis (3-allyl-4-hydroxyphenyl) sulfone was changed to 4,4'-dihydroxydiphenyl sulfone in the preparation of the (4) color developer / sensitizer dispersion liquid of Example 1. In the same manner as above, the heat-sensitive recording linerless label of Comparative Example 1 was produced.

Comparative Example 2
Except for changing the bis (3-allyl-4-hydroxyphenyl) sulfone to 4-hydroxy-4'-allyloxydiphenyl sulfone in the preparation of the color developer / sensitizer dispersion in Example 1 (4). The heat-sensitive recording linerless label of Comparative Example 2 was produced in the same manner as in Example 1.

Comparative Example 3
In the preparation of (8) release layer coating solution 1 of Example 1, the release layer coating solution 1 was changed to the following release layer coating solution 4 (thermosetting type), and the release layer coating solution 4 was changed to the solid content. Example 1 except that a gravure coating method was applied so that the coating amount was 1.5 g / m ^2, and then thermosetting was performed using a dryer box (heating temperature 120 ° C.) to form a release layer. In the same manner as above, the heat-sensitive recording linerless label of Comparative Example 3 was produced. The Beck smoothness on the surface of the release layer was 1000 seconds.

(8) Preparation of release layer coating liquid 4 100 parts of vinyl group-containing solvent-free silicone resin (manufactured by Toray Dow Corning Co., Ltd., BY24-468C)
Curing catalyst 3 parts (Platinum catalyst SRX212 manufactured by Toray Dow Corning Co., Ltd.)

Comparative Example 4
In the production of the (10) thermal recording linerless label of Example 1, a hot melt adhesive (manufactured by Sekisui Fuller Co., Ltd., JM-6197) was used as an acrylic emulsion adhesive (manufactured by Saiden Chemical Co., Ltd., AT-1202). After coating with a roll coater coating method so that the solid content coating amount is 20 g / m ² , the same as in Example 1 except that the solid content is dried using a dryer box (heating temperature 70 ° C.). The heat-sensitive recording linerless label of Comparative Example 4 was prepared.

Comparative Example 5
In the preparation of the heat-sensitive recording material (7) of Example 1, the following protective layer coating liquid was applied onto the heat-sensitive recording layer by an air knife coating method so that the solid content coating amount was 2.0 g / m ² . After drying, a protective layer was formed by further performing a calendar treatment using a super calendar. The Beck smoothness on the surface of the protective layer after the calendar treatment was 2000 seconds. Then, the heat-sensitive recording linerless label of Comparative Example 5 was produced in the same manner as in Example 1 except that the release layer was formed on the protective layer. The Beck smoothness on the surface of the release layer was 3000 seconds.

(11) Preparation of protective layer coating solution 800 parts of 5% amorphous silica aqueous dispersion (manufactured by Mizusawa Industrial Chemicals, Inc., Mizukasil (registered trademark) P-527 dispersed in water)
1000 parts of 10% silanol-modified polyvinyl alcohol aqueous solution (manufactured by Kuraray Co., Ltd., 25-98R (R-1130) dissolved in water)
25 parts of 20% zinc stearate aqueous dispersion (manufactured by Chukyo Yushi Co., Ltd., hydrin L-536 diluted with water)
100 parts of 20% glyoxal aqueous solution

The heat-sensitive recording linerless labels of Examples 1 to 5 and Comparative Examples 1 to 5 obtained as described above were obtained using a paper tube having an inner diameter of 1.5 inches and a wall thickness of 2 mm, and having a width of 60 mm. A roll having a length of 60 m (the adhesive layer is on the core side (inside)) was cut and wound, and subjected to the following evaluation. The results of each are shown in Table 1.

<Color development sensitivity>
For each of the produced heat-sensitive recording linerless labels, a label printer (Shinsei Industries Co., Ltd .: HALLO (registered trademark) neo-7 H23T-CL) was used in an environment of 23 ° C. and 50% RH to print a density of 8, Solid black printing was performed under the conditions that the printing speed was 130 mm / sec and the linerless setting was ON. After affixing the printed thermal recording linerless label on neutral woodfree paper with a basis weight of 60 g / m ² , the optical density of the printed part is measured in an environment of 23 ° C. and 50% RH (Made by GretagMacbeth, RD19). It was measured in (black mode) and evaluated according to the following criteria.

⊚: Optical density of black solid printing part is 1.4 or more ○: Optical density of black solid printing part is 1.2 or more and less than 1.4 ×: Optical density of black solid printing part is less than 1.2 or printing is missing Stands out

<Image storage after long-term storage>
For each of the produced heat-sensitive recording linerless labels, a label printer (Shinsei Industries Co., Ltd .: HALLO neo-7 H23T-CL) was used in an environment of 23 ° C. and 50% RH, and the printing density was 8 and the printing speed was 130 mm /. Solid black printing was performed under the condition that the linerless setting was ON for seconds. After attaching the printed thermal recording linerless label to a neutral woodfree paper with a basis weight of 60 g / m ² , store it in an environment of 23 ° C. and 50% RH for 90 days, and then store it in an environment of 23 ° C. and 50% RH. Below, the optical density of the printed portion was measured with a densitometer (manufactured by GretagMacbeth, RD19) (black mode), and evaluated according to the following criteria.

⊚: Optical density of black solid printing part is 1.2 or more ○: Optical density of black solid printing part is 1.0 or more and less than 1.2 ×: Optical density of black solid printing part is less than 1.0

<Skin fog resistance>
After each of the produced heat-sensitive recording linerless labels is attached to neutral woodfree paper with a basis weight of 60 g / m ² , the optical density of the blank paper is measured in an environment of 23 ° C. and 50% RH (manufactured by Gretag Macbeth). , RD19) (black mode) and evaluated according to the following criteria.

⊚: Optical density of blank paper part is less than 0.1 ○: Optical density of blank paper part is 0.1 or more and less than 0.2 ×: Optical density of blank paper part is 0.2 or more

As is clear from the description in Table 1, it can be seen that the present invention provides a heat-sensitive recording linerless label having excellent color development sensitivity, image storage stability after long-term storage, and skin fog resistance.

Claims (2)

One surface of the support has a heat-sensitive recording layer containing at least a dye precursor and a color developer, and a release layer on the heat-sensitive recording layer containing an ultraviolet curable silicone resin without a protective layer. A heat-sensitive recording linerless label having an adhesive layer on the other side of the support, wherein the heat-sensitive recording layer is a bis (3-allyl-4-hydroxyphenyl) sulfone or 3- (3) as a color developer. -Tosyl ureido) A thermal recording linerless label containing phenyl-p-toluenesulfonate, wherein the pressure-sensitive adhesive layer contains a hot-melt pressure-sensitive adhesive. The heat-sensitive recording linerless label according to claim 1, wherein the release layer contains an organopolysiloxane compound having an acrylic group and / or a methacrylic group as a functional group in the molecule as an ultraviolet curable silicone resin.