JP4943967B2 - Thermal adhesive label and method for thermal activation of the thermal adhesive label - Google Patents

Description

  The present invention relates to a heat-adhesive label that does not require a release paper that exhibits adhesiveness by heat and a method for thermally activating the heat-adhesive label.

In recent years, sticky thermosensitive recording labels have been used in a wide range of fields such as the POS field, and these labels usually have a release paper affixed on an adhesive layer.
While such labels are useful, they have a number of drawbacks. That is, the release paper is a waste of resources because it is peeled off and discarded when a label is attached to an article. It is also a waste of space for the wound body, which leads to high costs. Furthermore, when a label is affixed to an article, the work of peeling the release paper is troublesome.
In order to solve these problems, several heat-sensitive recording labels having an adhesive property that do not use release paper have been proposed.
For example, Patent Document 1 proposes a hot-melt adhesive, but the hot-melt adhesive is sticky when heated, but immediately solidifies when cooled, so that the delay property is short, and the thermal head It is difficult to use it like a normal heat-sensitive label by heating in such a short time.

Further, in Patent Documents 2 to 4 and the like, a pressure-sensitive adhesive is formed on a protective layer provided on a heat-sensitive recording layer in order to isolate (block or seal) the protective layer during winding. Liner-less thermal recording labels have been proposed, such as those provided with a release layer. However, these heat-sensitive recording labels that do not use release paper have not been put into practical use due to problems such as weak adhesive strength and inability to print on the surface of the heat-sensitive recording layer.
Patent Document 5 proposes a method using a heat-sensitive adhesive (thermal adhesive) as a functional pressure-sensitive adhesive, but this is particularly inferior to the current thermal recording label. In addition, the heat-sensitive adhesive obtained by these methods has relatively good adhesion to paper, PET film, etc., but PVC wrap (PVC wrap) and polyethylene wrap (PE wrap) used in the food POS field. The adhesive strength to the adherend and the corrugated cardboard used for logistics is weak and has not reached the practical level.

Patent Documents 6 to 8 disclose mere heat-adhesive labels that do not have a heat-sensitive recording layer. However, these heat-adhesive labels, on the other hand, use materials that have strong adhesiveness when heated, so that even when stored in winding, some adhesiveness is manifested depending on the storage temperature, and the front and back surfaces stick to each other and block. Happens.
In order to prevent this blocking, it is necessary to control the adhesiveness, and in order to achieve both adhesive strength and blocking resistance, it has been proposed to use an appropriate resin for the adhesive, but it still has adhesive strength. And blocking resistance have not been achieved at the same time. If blocking is prevented, the adhesiveness will eventually be weakened, and thermal adhesion that achieves both adhesive strength and blocking resistance for adherends such as PVC wrap, polyethylene wrap and cardboard. In fact, sex labels have not yet been developed, either simple labels or thermal recording labels.
Patent Documents 9 to 10 propose a pressure-sensitive adhesive material in which a solid plasticizer layer is provided on a pressure-sensitive adhesive layer as a technique for achieving both adhesive force and blocking property. However, this label has problems such as insufficient adhesion to corrugated cardboard, solid plasticizer crystallizing with time and lowering adhesion, and insufficient sealing layer function and blocking.

Patent Document 11 discloses a thermal recording label in which a barrier layer that is activated by heat and develops adhesiveness is provided on a thermal adhesive layer for the purpose of preventing blocking during winding. In this label, the adhesiveness is sufficiently strong because of the heat-sensitive adhesive, and the barrier layer itself exhibits adhesiveness when heat is applied, so the adhesiveness is strong, but specifically, since it contains a solid plasticizer at room temperature, the barrier layer The function is not sufficient and blocking occurs. Therefore, in order to satisfy the blocking resistance, it is necessary to increase the thickness of the barrier layer. However, in that case, the adhesiveness when heat is applied becomes insufficient, and the adhesive force to PVC wrap, polyethylene wrap and cardboard becomes insufficient. It is difficult to achieve both blocking resistance and adhesive strength. Furthermore, the solid plasticizer contained in the barrier layer has a problem that crystallization occurs over time and the adhesive strength decreases. In particular, the decrease in adhesive strength to cardboard is remarkable.
Patent Document 12 discloses a heat-sensitive adhesive sheet in which a thermoplastic resin is laminated on a heat-sensitive adhesive layer from a solid plasticizer and a thermoplastic resin. However, since this product contains a solid plasticizer in the heat-sensitive adhesive layer, the adhesive to the cardboard is insufficient, the solid plasticizer crystallizes over time, and the adhesive strength decreases over time. There is a problem to do.
Patent Document 13 discloses that a heat-sensitive adhesive sheet in which a hot-melt resin is provided on a heat-sensitive adhesive layer is brought into contact with a heat medium typified by a thermal head to develop an adhesive force. However, since the thermal sensitivity is low and the active surface is not uniform, the adhesive force is uneven.

JP 2000-96015 A Japanese Utility Model Publication No.59-43979 Japanese Utility Model Publication No.59-46265 JP 60-54842 A JP-A 63-303387 Japanese Unexamined Patent Publication No. 63-152686 JP-A-6-57226 JP-A-6-57233 JP-A-8-41431 JP 2001-66991 A JP-A-9-20079 JP-A-11-279495 JP 2006-84607 A

  In the present invention, in view of the current state of the above-mentioned thermal recording label or mere heat-adhesive label, a pressure-sensitive adhesive layer and a shielding layer (seal layer) made of a metal or alloy that is melted by heating are arranged in this order on one side of the support. A linerless heat-adhesive label provided with a heat-sensitive recording layer on the other side of the support, which has a strong adhesive force to an adherend, in particular, an adhesive force to cardboard, PVC wrap, polyethylene wrap, etc. It is an object of the present invention to provide a heat-adhesive label having no tackiness and good blocking resistance and a method for thermally activating the heat-adhesive label.

The above problems are solved by the following inventions (1) to (6).
(1) A heat-adhesive label characterized in that a pressure-sensitive adhesive layer and a shielding layer made of a metal or alloy that melts by heating are provided in this order on one side of the support.
(2) The heat-adhesive label according to (1), wherein the shielding layer contains tin.
(3) The heat-adhesive label according to (1) or (2), wherein a protective layer comprising at least a heat-fusible substance and a binder resin is provided on the shielding layer.
(4) The heat-adhesive label according to any one of (1) to (3), wherein a heat-sensitive recording layer is provided on the side of the support that does not have an adhesive layer.
(5) A thermal activation method for a thermoadhesive label, comprising heating the thermoadhesive label according to any one of (1) to (4) with a thermal head.
(6) The method for thermally activating a heat-adhesive label according to (5), wherein the pressure-sensitive adhesive layer is activated after forming an image on the heat-sensitive recording layer.

Hereinafter, the present invention and its embodiments will be described in detail.
The heat-adhesive label of the present invention is formed by laminating a pressure-sensitive adhesive layer and a shielding layer made of a metal or alloy that melts by heating in this order on one side of the support. Since the expression of the adhesiveness of the agent layer can be prevented, the surface is non-adhesive at room temperature, and adhesion to other substances that come into contact does not occur. On the other hand, at the time of heating, the material of the shielding layer melts and agglomerates, so that there is a hole in the shielding layer and expresses adhesiveness, and sufficient adhesiveness to cardboard, vinyl chloride wrap, polyethylene wrap, etc. can be expressed. In addition, since the adhesive layer does not exhibit adhesiveness during storage, printing on the thermal recording layer is possible when a thermal recording layer is provided on the side of the support that does not have the adhesive layer. is there.
The pressure-sensitive adhesive layer in the present invention may be a heat-sensitive pressure-sensitive adhesive layer or a pressure-sensitive pressure-sensitive adhesive layer, and after the shielding layer is melted and aggregated by heating, a label is attached by heating or pressurization depending on the properties of the pressure-sensitive adhesive layer. Good.

  In the heat-adhesive label of the present invention, the heating means for developing the pressure-sensitive adhesive layer is not particularly limited, and hot plate, hot air, hot air, infrared ray, heating roll, thermal head, ceramic heater, laser irradiation, infrared ray A well-known thing, such as a lamp, can be used. Among them, the thermal head is small in size and consumes little power, and it can control heat generation on demand and perform thermal activation simultaneously with energization, thus reducing energy consumption and efficiently transferring heat to the adhesive layer. This is particularly effective because it has the advantage that it can be activated even if the sex label is moved at a high speed. Furthermore, among the thermal heads, the one having the heat generating portion provided on the near edge, corner edge, end face or the like is effective because components constituting the thermally activated adhesive layer are not easily transferred to the thermal head. The heat-adhesive label is used by sticking to an adherend after heating the pressure-sensitive adhesive layer with such a heating means to express the adhesiveness.

Since the heat-adhesive label of the present invention has a shielding layer, surface stickiness does not occur in a normal state, the blocking resistance can be improved, the blocking resistance is not too strong, and the heat-adhesive label for thermal recording is further provided. In this case, the surface of the heat-sensitive recording layer is excellent in printability because there is no conventional silicon processing for blocking resistance.
Further, the thermoadhesive label having the thermosensitive recording layer of the present invention does not require a release paper. Then, the thermal recording layer side is heated first to form an image of character information, etc., and the adhesive layer is subsequently heated so that continuous label issuance at high speed without causing paper jams in the printer. Can be realized.
As the pressure-sensitive adhesive of the pressure-sensitive adhesive layer of the present invention, various pressure-sensitive adhesives used in this field can be appropriately used. Specific examples include polyvinyl acetate, vinyl acetate / ethylene copolymer, vinyl acetate / acrylic acid ester copolymer, vinyl acetate / maleic acid ester copolymer, ethylene / acrylic acid copolymer, epoxy resin, phenol Examples include, but are not limited to, emulsions such as resins, starch derivatives, gelatin, casein, polyvinyl alcohol, carboxycellulose, cellulose derivatives such as methylcellulose and hydroxyethylcellulose, and water-soluble resins such as polyvinylpyrrolidone.

The heat-sensitive pressure-sensitive adhesive layer contains a thermoplastic resin, a heat-meltable substance, and a tackifier as main components, and further contains other components such as a non-meltable substance as necessary.
The thermoplastic resin is not particularly limited and may be appropriately selected depending on the intended purpose. However, when a thermoplastic resin that is adhesive at room temperature, specifically, a glass transition temperature of −30 ° C. or lower is used, the thermoplastic resin is adhesive. This is preferable because the force is improved.
Examples of the thermoplastic resin include natural rubber latex obtained by graft copolymerization with a vinyl monomer, acrylic ester copolymer, methacrylic ester copolymer, acrylic ester-methacrylic ester copolymer, acrylic ester-styrene. A copolymer, an acrylic ester-methacrylic ester-styrene copolymer, an ethylene-vinyl acetate copolymer, etc. are mentioned. These may be used alone or in combination of two or more.
The heat-meltable substance is solid at room temperature, so it does not give plasticity to the resin, but it melts by heating and swells or softens the resin to develop adhesiveness, and then slowly crystallizes, so the heat source was removed. The adhesiveness can be maintained for a long time.
Those having a melting point of 70 ° C. or higher are preferably used, and examples thereof include benzotriazole, hydroxybenzoic acid ester, and phosphine compound. These can be used by pulverizing them to a volume average particle size of 10 μm or less, preferably 3 μm or less.
The tackifier is added to improve the adhesive strength of the heat-sensitive adhesive layer, and is not particularly limited and can be appropriately selected from known ones according to the purpose. For example, a rosin derivative (for example, Rosin, polymerized rosin, hydrogenated rosin), terpene resins (for example, terpene resins, aromatic modified terpene resins, terpene phenol resins, hydrogenated terpene resins), petroleum resins, phenol resins, xylene resins and the like. .
The application amount of the pressure-sensitive adhesive is preferably 5 to 35 g / m ² , more preferably 10 to 25 g / m ² on a dry basis.

The shielding layer of the present invention is a layer in which a heated portion can be melted by heat, and is made of a thin film of a single metal or an alloy thereof. Specifically, it consists of metals, such as Al, Ni, Sn, Zn, Ti, Te, In, Bi, and Pb, or these alloys. A metal compound can be used as long as it is easily melted by heat.
The shielding layer can be formed by vacuum deposition, sputtering, plating, or the like. Alternatively, a metal foil can be attached to be provided.
The thickness of the shielding layer is 1-1000 nm, preferably 10-500 nm. If the shielding layer is too thin, voids are likely to be formed during production, so that the adhesive resin oozes out and blocking tends to occur when the heat-adhesive label is placed on top of each other or stored in a roll shape. On the other hand, if the shielding layer is too thick, there is a problem that the heat sensitivity is lowered, and the metal lump produced by the collection of molten metal inhibits the contact with the adherend, so that the adhesive property is lowered.

A protective layer made of a heat-fusible substance and a binder resin can be provided for the purpose of transport failure when using a means for applying heat by contact or protection of the shielding layer.
As the heat-fusible substance, a substance that can impart activity in a non-heated state, melts with the heat of the thermal head, and quickly melts with the binder resin or the pressure-sensitive adhesive is preferable. Specifically, low molecular organic compounds are preferable, particularly compounds having a long-chain alkyl group such as fatty acid zinc and fatty acid amide, waxes such as carnauba wax and polyolefin wax, organic phosphorus compounds such as substituted phosphine and phosphate ester, benzotriazole A compound having a bulky portion such as hindered phenol is preferably used.
Although there is no restriction | limiting in particular in binder resin, Water-soluble resin is preferable, For example, various polyvinyl alcohol, a styrene butadiene rubber (SBR) emulsion, an acrylic emulsion, etc. are used.
The protective layer can be formed by pulverizing a heat-fusible substance with a sand mill or the like, and then mixing and applying it with a binder. The coating amount of the protective layer material is preferably 0.5 to 20 g / m ² and more preferably 1 to 15 g / m ² on a dry basis.

For the heat-sensitive recording layer, a colorless or light leuco dye and a developer are used as main components.
As the leuco dye (color former), those applied to this type of heat-sensitive recording material may be used alone or in admixture of two or more. For example, leuco compounds of dyes such as triphenylmethane, fluorane, phenothiazine, auramine, spiropyran, and indinophthalide are preferably used, but are not limited thereto.
Specific examples of such leuco dyes include those shown below.
3,3-bis (p-dimethylaminophenyl) -phthalide, 3,3-bis (p-dimethylaminophenyl) -6-dimethylamine phthalide (also known as crystal violet lactone), 3,3-bis (p- Dimethylaminophenyl) -6-diethylaminophthalide, 3,3-bis (p-diethylaminophenyl) -6-chlorophthalide, 3,3-bis (p-dibutylaminophenyl) phthalide, 3-cyclohexylamino-6-chlorofur Oran, 3-dimethylamino-5,7-dimethylfluorane, 3-diethylamino-7-chlorofluorane, 3-dimethylamino-7-methylfluorane, 3-diethylamino-7,8-benzfluorane, 3- Diethylamino-6-methyl-7-chlorofluorane, 3- (Np-tolyl-N-ethyl) Mino) -6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 2- [N- (3'-trifluoromethylphenyl) amino] -6-diethylaminofluor Oran, 2- [3,6-bis (diethylamine) -9- (o-chloroanilino) xanthylbenzoate lactam], 3-diethylamino-6-methyl-7- (m-trichloromethylanilino) fluorane, 3-diethylamino -7- (o-chloroanilino) fluorane, 3-di-n-butylamino-7- (o-chloroanilino) fluorane, 3-N-methyl-Nn-amylamino-6-methyl-7-anilinofluorane 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7 Anilinofluorane, 3- (N, N-diethylamino) -5-methyl-7- (N, N-dibenzylamino) fluorane, benzoylleucomethylene blue, 6'-chloro-8'-methoxy-benzoindolino- Spiropyran, 6'-bromo-3'-methoxy-benzoindolino-spiropyran, 3- (2'-hydroxy-4'-dimethylaminophenyl) -3- (2'-methoxy-5'-chlorophenyl) phthalide, 3- (2'-hydroxy-4'-dimethylaminophenyl) -3- (2'-methoxy-5'-nitrophenyl) phthalide, 3- (2'-methoxy-4'-dimethylaminophenyl) -3- (2'-Hydroxy-4'-chloro-5'-methylphenyl) phthalide, 3- (N-ethyl-N-tetrahydrofurfuryl) amino-6 Methyl-7-anilinofluorane, 3-N-ethyl-N- (2-ethoxypropyl) amino-6-methyl-7-anilinofluorane, 3-N-methyl-N-isobutyl-6-methyl- 7-anilinofluorane, 3-morpholino-7- (N-propyl-trifluoromethylanilino) fluorane, 3-pyrrolidino-7-m-trifluoromethylanilinofluorane, 3-diethylamino-5-chloro- 7- (N-benzyl-trifluoromethylanilino) fluorane, 3-pyrrolidino-7- (di-p-chlorophenyl) methylaminofluorane, 3-diethylamino-5-chloro-7- (α-phenylethylamino) ) Fluorane, 3- (N-ethyl-p-toluidino) -7- (α-phenylethylamino) fluorane, 3-diethylamino-7- (O-methoxycarbonylphenylamino) fluorane, 3-diethylamino-5-methyl-7- (α-phenylethylamino) fluorane, 3-diethylamino-7-piperidinofluorane, 2-chloro-3- (N- Methyltoluidino) -7- (pn-butylanilino) fluorane, 3- (N-methyl-N-isopropylamino) -6-methyl-7-anilinofluorane, 3-di-n-butylamino-6-methyl -7-anilinofluorane, 3,6-bis (dimethylamino) fluorane spiro (9,3 ')-6'-dimethylaminophthalide, 3- (N-benzyl-N-cyclohexylamino) -5 6-Benzo-7-α-naphthylamino-4'-bromofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3-diethi Ruamino-6-methyl-7-mesitidino-4 ', 5'-benzofluorane, 3-N-methyl-N-isopropyl-6-methyl-7-anilinofluorane, 3-N-ethyl-N-isoamyl -6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7- (2 ', 4'-dimethylanilino) fluorane and the like.

Further, as the developer used for the heat-sensitive recording layer, various electron-accepting compounds that cause the coloration by contacting the leuco dye under heat, a solvent, or the like, or an oxidizing agent, and the like are applied. Such a thing is conventionally well-known and the following are mentioned as the specific example, However It is not limited to these.
4,4'-isopropylidenediphenol, 4,4'-isopropylidenebis (o-methylphenol), 4,4'-s-butylidenebisphenol, 4,4'-isopropylidenebis (2-t-butylphenol) ), Zinc p-nitrobenzoate, 1,3,5-tris (4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanuric acid, 2,2- (3,4'-dihydroxydiphenyl) Propane, bis (4-hydroxy-3-methylphenyl) sulfide, 4- [β- (p-methoxyphenoxy) ethoxy] salicylic acid, 1,7-bis (4-hydroxyphenylthio) -3,5-dioxaheptane 1,5-bis (4-hydroxyphenylthio) -5-oxapentane, phthalic acid monobenzyl ester monocalcic acid, 4,4 -Cyclohexylidene diphenol, 4,4'-isopropylidenebis (2-chlorophenol), 2,2'-methylenebis (4-methyl-6-t-butylphenol), 4,4'-butylidenebis (6-t- Butyl-2-methyl) phenol, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,1,3-tris (2-methyl-4-hydroxy-5) -Cyclohexylphenyl) butane, 4,4'-thiobis (6-tert-butyl-2-methyl) phenol, 4,4'-diphenolsulfone, 4-isopropoxy-4'-hydroxydiphenylsulfone, 4-benzyloxy-4 '-Hydroxydiphenyl sulfone, 4,4'-diphenol sulfoxide, isopropyl p-hydroxybenzoate, p-hydride Benzyl roxybenzoate, benzyl protocatechuate, stearyl gallate, lauryl gallate, octyl gallate, 1,3-bis (4-hydroxyphenylthio) -propane, N, N'-diphenylthiourea, N, N'- Di (m-chlorophenyl) thiourea, salicylanilide, methyl bis- (4-hydroxyphenyl) acetate, benzyl bis- (4-hydroxyphenyl) acetate, benzyl 1,3-bis (4-hydroxyphenyl) acetate, 1, 3-bis (4-hydroxycumyl) benzene, 1,4-bis (4-hydroxycumyl) benzene, 2,4'-diphenolsulfone, 2,2'-diallyl-4,4'-diphenolsulfone 3,4-dihydroxyphenyl-4'-methyldiphenylsulfone, 1-acetyloxy-2-naphthoic acid Lead, zinc 2-acetyloxy-1-naphthoate, zinc 2-acetyloxy-3-naphthoate, α, α-bis (4-hydroxyphenyl) -α-methyltoluene, antipyrine complex of zinc thiocyanate, tetrabromo Bisphenol A, tetrabromobisphenol S, 4,4'-thiobis (2-methylphenol), 4,4'-thiobis (2-chlorophenol) and the like.

In the present invention, the developer used in the heat-sensitive recording layer is preferably 1 to 20 parts by weight, more preferably 2 to 10 parts by weight with respect to 1 part by weight of the color former. These color formers and developers can be used alone or in admixture of two or more.
A binder resin used for the heat-sensitive recording layer is preferably a resin having a hydroxyl group or a carboxyl group in the molecule. Examples of such resins include polyvinyl acetals such as polyvinyl butyral and polyvinyl acetoacetal, cellulose derivatives such as ethyl cellulose, cellulose acetate, cellulose acetate propionate, and cellulose acetate butyrate, and epoxy resins. It is not limited. These binder resins are used alone or in admixture of two or more.

In the heat-sensitive recording layer, a heat-fusible substance can be used alone or in admixture of two or more as an auxiliary additive component.
Examples of the heat-fusible substance include, in addition to higher fatty acids or esters thereof, amides, metal salts, various waxes, condensates of aromatic carboxylic acids and amines, benzoic acid phenyl esters, higher linear glycols, 3, Examples thereof include, but are not limited to, those having a melting point of about 50 to 200 ° C., such as 4-epoxy-hexahydrophthalate dialkyl, higher ketone, and other heat-fusible organic compounds.
Furthermore, when obtaining the heat-sensitive recording layer in the present invention, if necessary, additives such as fillers, surfactants, lubricants, pressure color developing inhibitors and the like commonly used in this type of heat-sensitive recording layer are added to the heat-sensitive recording layer. It can be used in combination as long as the transparency is not impaired.
Examples of the filler include calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, kaolin, talc, surface-treated inorganic fine powders such as calcium and silica, and urea. -Organic fine powders such as formalin resin, styrene / methacrylic acid copolymer, polystyrene resin, and vinylidene chloride resin.
Examples of the lubricant include higher fatty acids and metal salts thereof, higher fatty acid amides, higher fatty acid esters, various animal, vegetable, mineral, and petroleum waxes.

The heat-sensitive recording layer is prepared by uniformly dispersing or dissolving the color former, developer, and binder resin in a solvent, and coating and drying this on a support made of fine paper or film. Is not particularly limited. The dispersed particle size of the thermal recording layer coating solution is preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 1 μm or less.
The film thickness of the heat-sensitive recording layer is about 1 to 50 μm, preferably about 3 to 20 μm, although it depends on the composition of the heat-sensitive recording layer and the application of the thermoadhesive label.
The recording method of the heat-sensitive recording layer of the present invention may be any of a thermal pen, a thermal head, laser heating and the like depending on the purpose of use, and is not particularly limited.
The support used in the present invention is not particularly limited. For example, in addition to paper, cloth, and film, transparent materials include polyester films such as polyethylene terephthalate and polybutylene terephthalate, cellulose derivative films such as cellulose triacetate, and polypropylene. Polyolefin films such as polyethylene, polystyrene films, transparent films obtained by laminating these, and the like are common.

In the present invention, a protective layer can be provided on the thermosensitive recording layer. This protective layer is effective for improving the so-called head matching properties such as transparency, chemical resistance, water resistance, friction resistance, light resistance, thermal head durability, corrosion resistance, and slipperiness of the thermal recording layer.
The protective layer includes a film mainly formed of a water-soluble resin or a hydrophobic resin, a film mainly formed of an ultraviolet curable resin or an electron beam curable resin, and the like. Examples of such resins include water-soluble resins, aqueous emulsions, hydrophobic resins, ultraviolet curable resins, and electron beam curable resins.
Specific examples of the water-soluble resin include, for example, polyvinyl alcohol, modified polyvinyl alcohol, cellulose derivatives (methylcellulose, methoxycellulose, hydroxycellulose, etc.), casein, gelatin, polyvinylpyrrolidone, styrene-maleic anhydride copolymer, diisobutylene- Maleic anhydride copolymer, polyacrylamide, modified polyacrylamide, methyl vinyl ether-maleic anhydride copolymer, carboxy-modified polyethylene, polyvinyl alcohol / acrylamide block copolymer, melamine-formaldehyde resin, urea-formaldehyde resin, etc. .

Examples of the resin or hydrophobic resin for aqueous emulsion include polyvinyl acetate, polyurethane, styrene / butadiene copolymer, styrene / butadiene / acrylic copolymer, polyacrylic acid, polyacrylic acid ester, and vinyl chloride / acetic acid. Examples thereof include vinyl copolymers, polybutyl methacrylate, polyvinyl butyral, polyvinyl acetal, methyl cellulose, ethyl cellulose, and ethylene / vinyl acetate copolymers.
Further, copolymers of these resins and silicon segments are also preferably used. These may be used alone or in combination, and if necessary, a curing agent may be added to cure the resin.
The type of the ultraviolet curable resin is not particularly limited as long as it uses a monomer, oligomer, or prepolymer that undergoes a polymerization reaction upon irradiation with ultraviolet rays and is cured to become a resin, and various known ones can be used.
The type of the electron beam curable resin is not particularly limited, but is preferably a material mainly composed of an electron beam curable resin having a branched molecular structure of five or more functional groups having a polyester skeleton and a silicon-modified electron beam curable resin. It is.

In order to improve the head matching property, inorganic and / or organic fillers and lubricants can be added to the protective layer of the heat-sensitive recording layer as long as the surface smoothness is not deteriorated. The particle size of the filler is preferably 0.3 μm or less. In this case, the filler is preferably selected so that the amount of oil supply is 30 ml / 100 g or more, more preferably 80 ml / 100 g or more.
As these inorganic and / or organic fillers, one or more kinds can be selected from pigments commonly used in this type of heat-sensitive recording layer. Specific examples include calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, surface-treated inorganic pigments such as calcium and silica, urea-formalin resin, styrene / Organic pigments such as methacrylic acid copolymer and polystyrene resin. As the lubricant, those mentioned in the description of the heat-sensitive recording layer can be used.
The method for applying the protective layer of the thermosensitive recording layer is not particularly limited, and a conventionally known method can be employed.
A preferable thickness of the protective layer is 0.1 to 20 μm, more preferably 0.5 to 10 μm. If the thickness of the protective layer is too thin, the functions of the protective layer such as the storage stability of the heat-adhesive label and head matching will be insufficient, and if it is too thick, the thermal sensitivity of the thermosensitive recording layer will be reduced, and the cost will be reduced. It is disadvantageous.

In the present invention, a heat insulating layer (under layer) is provided between the support and the pressure-sensitive adhesive layer and / or between the support and the thermosensitive recording layer as necessary.
By providing this heat insulating layer, the thermal energy efficiency of the thermal head can be improved and the thermal activation temperature can be lowered. Further, when a heat-sensitive recording layer is provided, color development of the heat-sensitive recording layer can be blocked when the pressure-sensitive adhesive layer is thermally activated.
As a material for the heat insulating layer, together with fine hollow particles and a binder, if necessary, a pigment, auxiliary additives commonly used in this type of heat-sensitive recording material, for example, a heat-fusible substance, a filler, a surfactant, etc. are used in combination. can do. In this case, as a specific example of the heat-fusible substance, the same material as the heat-fusible substance described in the description of the heat-sensitive recording layer is used.

Examples of the resin used for the heat insulating layer containing minute hollow particles include latex such as SBR, MBR and NBR, polyvinyl alcohol, cellulose derivatives, starch and derivatives thereof, carboxyl group-modified polyvinyl alcohol, polyacrylic acid and derivatives thereof, styrene / acrylic Acid copolymer and derivatives thereof, poly (meth) acrylamide and derivatives thereof, styrene / acrylic acid / acrylamide copolymer, amino group-modified polyvinyl alcohol, epoxy-modified polyvinyl alcohol, polyethyleneimine, isobutylene / maleic anhydride copolymer And water-soluble polymer resins such as derivatives thereof and the like, but are not necessarily limited thereto.
In addition, as the filler, for example, calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, surface-treated inorganic fine powder such as calcium and silica, Examples thereof include organic fine powders such as urea-formalin resin, styrene / methacrylic acid copolymer, and polystyrene resin.

Examples of the heat insulating layer in the present invention include a non-foaming heat insulating layer using plastic spherical hollow particles having a hollowness of 30% or more or a porous pigment having a thermoplastic resin as a shell, and a foaming heat insulating layer using a foamable filler. However, a non-foaming heat insulating layer is preferable.
The plastic spherical hollow particles contain air or other gas inside, and are fine hollow particles that are already in a foamed state, preferably having a number average particle diameter of 2.0 to 20 μm, preferably 3 to 10 μm. Are more preferred. When the number average particle diameter (particle outer diameter) is smaller than 2.0 μm, there are production problems such as it is difficult to obtain an arbitrary hollowness, and there is a problem in terms of cost. When the size is large, the smoothness of the surface after coating and drying is lowered, so that the adhesion to the thermal head is lowered, the dot reproducibility is deteriorated, and the sensitivity improvement effect is lowered. Accordingly, it is desirable that the particle diameter is in the above range and at the same time the particle distribution spectrum is uniform with little variation.
The plastic spherical hollow particles preferably have a hollowness of 30% or more, and more preferably 50% or more. When the hollowness is less than 30%, the heat insulation is insufficient, so the thermal energy from the thermal head is released to the outside of the heat-adhesive label through the support, and the color development sensitivity is not improved. The heat insulation effect of the converted thermal energy is small, the activation effect of the heat-sensitive adhesive is inferior, and the expression of adhesiveness is weakened.
In addition, the hollowness here is the ratio of the volume of the hollow portion (internal void portion) to the entire volume of the hollow fine particles.

As the thermoplastic resin used as the shell of the plastic spherical hollow particles, a copolymer resin mainly composed of vinylidene chloride and acrylonitrile is particularly preferable.
Other porous pigments used in the heat insulating layer of the present invention include organic pigments such as urea formaldehyde resin and inorganic pigments such as shirasu earth, but are not necessarily limited thereto.
In order to provide a non-foaming heat insulating layer between the support and the heat-sensitive recording layer and / or between the support and the pressure-sensitive adhesive layer, the plastic spherical hollow particles may be prepared by using a known water-soluble polymer or aqueous polymer emulsion. It is obtained by dispersing with water together with a binder, etc., applying this to the surface of the support and drying. In this case, the coating amount of the hollow particles is at least 1 g per 1 m ² of the support, preferably about ^{2 to} 15 g, and the coating amount of the binder resin is such that the non-foaming heat insulating layer is strongly bonded to the support. The amount may be sufficient, and is usually 2 to 50% by weight based on the total amount of the hollow particles and the binder resin.

In the present invention, the binder used when forming the non-foamable heat insulating layer is appropriately selected from conventionally known water-soluble polymers and / or aqueous polymer emulsions.
Specific examples include water-soluble polymers such as polyvinyl alcohol, starch and derivatives thereof, cellulose derivatives such as methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, and ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide / acrylic. Acid ester copolymer, acrylamide / acrylic ester / methacrylic acid terpolymer, styrene / maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, Casein etc. are mentioned.
Examples of the aqueous polymer emulsion include latex such as styrene / butadiene copolymer, styrene / butadiene / acrylic copolymer, vinyl acetate resin, vinyl acetate / acrylic acid copolymer, and styrene / acrylic acid ester copolymer. And emulsions such as acrylic ester resins and polyurethane resins.

According to the present invention, there are provided a heat-adhesive label having a strong adhesive force to an adherend, particularly an adhesive force to corrugated cardboard, having no tackiness and good blocking resistance, and a method for thermally activating the heat-adhesive label. Can be provided.
In addition, there are advantages that the apparatus used for thermal activation is small and consumes less power, and that the work efficiency of label manufacture is excellent.

  Hereinafter, the present invention will be described in more detail with reference to examples. The parts and% shown below are based on weight.

[Example 1]
(A liquid) and (B liquid) were prepared by dispersing a mixture having the following composition using a sand mill so that the volume average particle diameter was 2.0 μm or less.
(Liquid A) Dye dispersion liquid 3-Dibutylamino-6-methyl-7-anilinofluorane ... 20 parts Polyvinyl alcohol 10% aqueous solution (Kuraray Co., Ltd., PVA-318) 20 parts Water 60 parts ( Liquid B) Developer dispersion liquid 4-hydroxy-4'-isopropoxydiphenylsulfone 10 parts Polyvinyl alcohol 10% aqueous solution (Kuraray Co., PVA-318) 25 parts Calcium carbonate (Shiraishi Calcium Co., Ltd. Tunex E): 15 parts Water: 50 parts Next, the mixture was stirred and mixed so that the weight ratio of the above (A liquid) and (B liquid) was (A liquid) :( B liquid) = 1: 8. A layer forming liquid (C liquid) was obtained.
Next, this (Liquid C) was applied and dried on the surface of a high-quality paper having a basis weight of 80 g / m ² so that the dry adhesion amount was 5 g / m ^2, and a thermal recording layer was provided. The paper was formed with a heat-sensitive recording layer by supercalendering so that the smoothness was 600 to 700 seconds.
Next, pressure-sensitive adhesive E-1054K manufactured by Soken Chemical Co., Ltd. was applied and dried on the back surface of the heat-sensitive recording layer-formed paper so that the dry adhesion amount was 20 g / m ² to provide a pressure-sensitive adhesive layer.
Finally, a shielding layer made of a tin thin film having a thickness of 100 nm and a thickness of 1 × 10 ⁻³ Pa was provided on the pressure-sensitive adhesive layer by a vacuum deposition apparatus manufactured by Edwards Co., to obtain a heat-adhesive label of Example 1.

[Example 2]
A thermoadhesive label of Example 2 was obtained in the same manner as in Example 1 except that the tin thin film was changed to an aluminum thin film.

Example 3
A heat-adhesive label of Example 3 was obtained in the same manner as in Example 1 except that the lead-free soldering SN97C of Nippon Superior Co., Ltd. was stretched and bonded to a foil having a thickness of 500 nm instead of the tin thin film. .

Example 4
<Heat fusible substance dispersion>
A liquid having the following composition was dispersed by a vertical sand mill to obtain a heat-fusible substance dispersion having a volume average particle diameter (median diameter) of 1 μm.
Polyolefin wax (manufactured by Mitsui Chemicals) ... 30 parts Polyvinyl alcohol (manufactured by Nippon Synthetic Chemical Industry, Goceran L-3266,
10 parts aqueous solution) ... 15 parts Surfactant (Nippon Emulsifier, Newcol 290M, 10% aqueous solution) ... 2 parts Water ... 53 parts <Protective layer coating solution>
The following materials were mixed and stirred to prepare a protective layer coating solution.
・ The above-mentioned thermofusible substance dispersion liquid: 100 parts ・ Acrylate ester copolymer aqueous emulsion [manufactured by Showa Polymer, Polysol PSA SE-4040, glass transition temperature (Tg):
-65 ° C, solid content concentration: 55%] ... 10 parts Tackifier (Arakawa Chemicals, terpene phenol main component, E-100, solid content concentration:
50%, softening point: 150 ° C.) 5 parts The above protective layer adjusting solution was applied on the tin thin film of the thermoadhesive label of Example 1 using a wire bar so that the dry adhesion amount was 5 g / m ^2. It dried and the heat-adhesive label of Example 4 was obtained.

Example 5
A heat-adhesive label of Example 5 was obtained in the same manner as in Example 3 except that the polyolefin wax in the heat-fusible substance dispersion of Example 3 was changed to triphenylphosphine.

[Comparative Example 1]
What was produced like Example 1 except the point which did not provide a tin thin film was evaluated as a heat adhesive label of comparative example 1.

[Comparative Example 2]
Instead of the tin thin film, an olefin / acrylic copolymer emulsion liquid (manufactured by Chuo Rika Kogyo Co., Ltd., Rikabond ET-1000) is applied and dried on the pressure-sensitive adhesive layer so that the dry adhesion amount is 3 g / m ^2, and hot melt A thermoadhesive label of Comparative Example 2 was obtained in the same manner as in Example 1 except that the layer was provided.

[Comparative Example 3]
The protective layer coating solution prepared in Example 3 was applied and dried at 5 g / m ² instead of the tin thin film for the adhesive layer of Example 1 to obtain a thermal adhesive label of Comparative Example 3. It was.

[Comparative Example 4]
Thermal adhesiveness of Comparative Example 4 in the same manner as Comparative Example 2 except that the olefin / acrylic copolymer emulsion liquid was replaced with a delayed tack paste (Regex Corp., DT-200) using a solid plasticizer. Got a label.

The thermal adhesive labels obtained in the above examples and comparative examples were evaluated. The evaluation criteria are as follows. The results are shown in Table 1.
[Tackiness]:
The thermal adhesive label was touched with a finger, and surface stickiness was evaluated according to the following criteria.
A: No tackiness
Δ: Weak tackiness
×: Tackiness

[Blocking property]:
When the heat-sensitive recording layer side and the pressure-sensitive adhesive layer side of the same label sample are brought into contact with each other and kept at a pressure of ² kg / cm ^{2 and} a temperature of 40 ° C. for 24 hours and left at room temperature, the sample is peeled off. The blocking property was evaluated according to the following rank.
A: No blocking (no peeling noise)
○: No blocking occurred (with peeling sound)
Δ: Slight blocking
×: Completely attached

[Active surface uniformity]:
Each heat-adhesive label is cut into a 40 mm × 120 mm rectangle, and using a thermal printing apparatus (manufactured by Okura Electric Co., Ltd., TH-PMD), head conditions: energy 0.50 mJ / dot, printing speed: 4 ms / line, Platen pressure: Thermally activated under the condition of 6 kgf / line. The activation uniformity of the sheet at this time was evaluated under the following conditions. Note that Comparative Example 1 was excluded from the evaluation because it adhered to the conveyance path.
A: The active surface is uniform.
○: A horizontal step or the like partially occurs on the active surface.
Δ: Gloss difference is observed on the entire active surface.
X: Unevenness such as dragging occurs on the active surface.

[Adhesiveness]:
The heat-activated heat-adhesive label is attached to an adherend (C liner cardboard) in the longitudinal direction with a 2 kg rubber roller under the conditions of a peeling angle of 180 degrees and a peeling speed of 300 mm / min after storage for 1 day. It was made to peel. The evaluation criteria for adhesive strength are as follows.
A: 1000 gf / 40 mm or more
○: 500 gf / 40 mm or more and less than 1000 gf / 40 mm
Δ: 100 gf / 40 mm or more and less than 500 gf / 40 mm
X: Less than 100 gf / 40 mm

Example 6
Using the SATO printer KY408, the heat-sensitive adhesive label produced in Example 1 was printed in the order of printing (image formation) and activation with the heat-sensitive recording surface facing up. I was able to read.

Claims (6)

  A heat-adhesive label, wherein a pressure-sensitive adhesive layer and a shielding layer made of a metal or alloy that melts by heating are provided in this order on one side of the support.   The thermoadhesive label according to claim 1, wherein the shielding layer contains tin.   The thermoadhesive label according to claim 1 or 2, wherein a protective layer comprising at least a heat-fusible substance and a binder resin is provided on the shielding layer.   The thermoadhesive label according to any one of claims 1 to 3, wherein a thermosensitive recording layer is provided on the side of the support that does not have an adhesive layer.   A method for thermally activating a heat-adhesive label, comprising heating the heat-adhesive label according to claim 1 with a thermal head.   6. The thermal activation method for a heat-adhesive label according to claim 5, wherein the pressure-sensitive adhesive layer is activated after forming an image on the heat-sensitive recording layer.