JPH10258477A - Heat sensitive tacky adhesive label - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide strong adhesive force to material to be adhered or particularly strong adhesive force to a vinyl chloride lap or polyethylene lap and excellent blocking resistance in winding state. SOLUTION: In the heat sensitive tacky adhesive label comprising a heat sensitive tacky adhesive layer obtained by sequentially laminating a first heat sensitive tacky adhesive layer containing at least any of thermoplastic resin, tackifier and solid plasticizer and a second heat sensitive tacky adhesive layer on a support, solid plasticizer content in the second layer is higher than that in the first layer. And, in the heat sensitive tacky adhesive layer, styrene-acrylic copolymer as the thermoplastic resin and/or acryl-butadiene copolymer may be contained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a delayed tack adhesive which is non-tacky at normal temperature but is activated by heating to exhibit tackiness, and then maintains tackiness for a long time even after the heating source is removed. It relates to the heat-sensitive adhesive label used.

[0002]

2. Description of the Related Art In recent years, recording labels, especially thermosensitive recording labels, have been used in a wide range of fields such as the POS field. However, in thermal labels, release paper is usually provided with a pressure-sensitive adhesive layer on the surface. The fact is that you can stick it. However, such a thermal recording label is effective but has many disadvantages. That is, the release paper has a larger area than the label itself, which is a product, and these release papers must be handled during use as well as during storage of the label for thermal recording. Post-processing must be performed after removal from the label. Therefore, from the viewpoint of recent ecology, there is a problem that a large amount of garbage is generated. In addition, since the productivity in the operation of attaching a label on a line is inferior, the production cost associated with the use of release paper, and It has problems such as high cost due to cost.

In order to solve these problems, a thermal recording label to which no release paper is attached has been proposed, for example, in Japanese Utility Model Application Laid-open No.
No. 43797, Japanese Utility Model Application Laid-open No. Sho 59-46265,
JP-A-54842 and the like have proposed a linerless thermosensitive recording label such as a microcapsule of an adhesive, a protective layer provided with a release agent layer for the adhesive, and the like. However, they have problems such as low adhesive strength and inability to print on the thermal surface, and have not been put to practical use.

A method using a heat-sensitive adhesive as a functional adhesive is disclosed in Japanese Patent Application Laid-Open No.
-11573, which are inferior to current thermal labels. In addition, the heat-sensitive adhesive obtained by these methods has relatively good adhesive strength to paper, PET film and the like, but is not suitable for adherends such as PVC wrap and polyethylene wrap used in the field of food POS. Has a low level of adhesion and has not yet reached a practical level. Furthermore,
In the layer constitution not including the heat-sensitive coloring layer, see JP-A-63-1988.
152686, JP-A-6-57226, JP-A-6-57
233, JP-A-7-268292 and the like propose resins in an adhesive in order to achieve both adhesive strength and blocking. However, these also have a high adhesive strength to each adherend and a high blocking ability. It was not satisfactory.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a linerless label having a heat-sensitive adhesive layer provided on a support in view of the above-mentioned current state of heat-sensitive adhesive labels. An object of the present invention is to provide a heat-sensitive pressure-sensitive adhesive label having a high pressure-sensitive adhesive strength and a good blocking resistance.

[0006]

That is, according to the present invention, there is provided (1) a first heat-sensitive adhesive layer containing at least one of a thermoplastic resin, a tackifier and a solid plasticizer on a support; A heat-sensitive adhesive label having a heat-sensitive adhesive layer obtained by sequentially laminating a second heat-sensitive adhesive layer with a second heat-sensitive adhesive layer.
A heat-sensitive adhesive label, wherein the solid plasticizer content in the heat-sensitive adhesive layer is higher than the solid plasticizer content in the first heat-sensitive adhesive layer; (2) the heat-sensitive adhesive layer; A heat-sensitive adhesive label characterized by containing a styrene / acrylic copolymer and / or an acrylic / butadiene copolymer as the thermoplastic resin; and (3) other than the heat-sensitive adhesive layer of the heat-sensitive adhesive label. , A heat-sensitive adhesive label comprising a leuco dye and a developer, and (4) the activation temperature of the heat-sensitive adhesive layer of the heat-sensitive adhesive label is as described above. (5) In the heat-sensitive adhesive label provided with the heat-sensitive color-forming layer, wherein the temperature is 10 ° C. or lower than the color-forming start temperature of the heat-sensitive color-forming layer, (5) between the support and the heat-sensitive color-forming layer; Between the support and the heat-sensitive adhesive layer A heat-sensitive adhesive label provided with a heat-insulating layer, and (6) the heat-insulating layer is a heat-insulating layer mainly composed of fine hollow particles having a hollowness of 30% or more and having a shell of a thermoplastic resin. Heat-sensitive adhesive label,
Is provided.

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that a first heat-sensitive adhesive layer containing at least one of a thermoplastic resin, a tackifier and a solid plasticizer, In the heat-sensitive adhesive layer formed by sequentially laminating the second heat-sensitive adhesive layer, the content of the solid plasticizer in the second heat-sensitive adhesive layer is made higher than that of the first heat-sensitive adhesive layer. As a result, the inventors have found that the above-mentioned object is achieved, and have accomplished the present invention. According to the study of the present inventors, by including a styrene / acrylic copolymer and / or an acrylic / butadiene copolymer as the thermoplastic resin,
Further, it has been found that it is possible to achieve both an improvement in adhesive strength and an improvement in blocking resistance.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As the thermoplastic resin of the heat-sensitive adhesive used in the present invention, the following resins can be used.
Polyvinyl acetate, polybutyl methacrylate, vinyl chloride / vinylidene chloride copolymer, synthetic rubber, vinyl acetate / 2-ethylhexyl acrylate copolymer, ethylene vinyl acetate copolymer, vinyl pyrrolidone / styrene copolymer,
Thermoplastic resins such as styrene / butadiene copolymer and vinylpyrrolidone / ethyl acrylate copolymer; When a styrene / acrylic copolymer and / or an acryl / butadiene copolymer is used as the thermoplastic resin, the adhesive strength to vinyl chloride wrap or polyethylene wrap is improved. The following acrylic monomers that can be copolymerized with styrene of the styrene / acrylic copolymer can be used. (MMA) methacrylate represented by methyl methacrylate, methacrylic acid, acrylate, acrylic acid, acrylonitrile, acrylamide, N-methylolamide and the like. In addition, acrylic monomers that can be copolymerized with butadiene of the acrylic / butadiene copolymer include:
The following can be used: Methyl methacrylate (MM
A) Methacrylic acid ester, methacrylic acid, acrylic acid ester, acrylic acid, acrylonitrile, acrylamide, N-methylolamide, etc. represented by A). Of these acrylic / butadiene copolymers, methyl methacrylate (MMA) / butadiene copolymer is particularly preferred,
By using this, the adhesive strength to each adherend, especially to vinyl chloride wrap (PV wrap) or polyethylene wrap (PE wrap) is strong, and the blocking resistance is also good. In particular, by using a styrene / acryl copolymer in combination with a methyl methacrylate (MMA) / butadiene copolymer, it is possible to achieve both better adhesive strength and better blocking resistance. The ratio of the acrylic / butadiene copolymer to the styrene / acrylic copolymer is preferably from 1: 0.2 to 5 by weight, and more preferably from 1: 0.3 to 3. If the ratio is less than 1: 0.2, the blocking resistance tends to decrease, and if it exceeds 1: 5, the adhesion to vinyl chloride wrap or polyethylene wrap decreases.

As the solid plasticizer used in the present invention, those exemplified below can be used, but are not necessarily limited thereto. Diphenyl phthalate, Dihexyl phthalate, Dicyclohexyl phthalate, Dihydroabiethyl phthalate, Dimethyl isophthalate, Sucrose benzoate, Ethylene glycol dibenzoate, Trimethylolethane tribenzoate, Glyceride tribenzoate, Pentaery tetrabenzoate Trit, sucrose octaacetate, tricyclohexyl citrate, N-cyclohexyl-p-toluenesulfonamide and the like. The content of the solid plasticizer in the heat-sensitive adhesive is increased by making the content in the second heat-sensitive adhesive layer larger than the content in the first heat-sensitive adhesive layer, thereby maintaining the adhesive strength and blocking. Performance can be improved. The content is preferably 30 to 70% by weight in the first heat-sensitive adhesive layer, and preferably 50 to 90% in the second heat-sensitive adhesive layer.
% By weight. When the content of the solid plasticizer in the second heat-sensitive adhesive layer is less than 50% by weight, the blocking property is reduced, and when it exceeds 90% by weight, the adhesiveness of the layer is reduced.

As the tackifier used in the present invention, those exemplified below can be used, but the present invention is not necessarily limited thereto. Rosin derivatives (rosin, polymerized rosin, hydrogenated rosin or their esters such as glycerin and pentaerythritol, resin acid dimer, etc.) terpene resin, petroleum resin, phenol resin, xylene resin and the like.

The melting point or softening point of the tackifier in the heat-sensitive adhesive is preferably 100 ° C. or higher, more preferably 1 ° C.
00 to 200 ° C. When the temperature is lower than 100 ° C., the blocking resistance decreases. The content of the tackifier in the heat-sensitive adhesive is preferably 3 to 30% by weight, and more preferably 5 to 25% by weight. If it is less than 3% by weight, the adhesive strength will be reduced, and if it exceeds 30% by weight, the blocking property will be reduced. The two-layered heat-sensitive adhesive layer used in the present invention contains a thermoplastic resin, a tackifier, and a solid plasticizer. It is not always necessary for all of these to be included in the heat-sensitive adhesive layer.

In the present invention, in order to improve the activation of the heat-sensitive adhesive layer, a substance having a heat-absorbing effect such as graphite is added to the heat-sensitive adhesive layer or between the support and the heat-sensitive adhesive layer. And halogen light and X
Activation with e-light is possible.

In the present invention, it is possible to provide a thermosensitive coloring layer containing a leuco dye and a developer on the other side of the thermosensitive adhesive layer. In the case of this thermal recording label,
The activation temperature of the heat-sensitive adhesive layer is preferably higher by 10 ° C. or more than the color-forming start temperature of the heat-sensitive coloring layer, but is not necessarily limited.

The term "coloring onset temperature of the thermosensitive coloring layer" as used in the present invention means that the thermosensitive coloring layer is colored under a condition of 2 kg / cm and 21 seconds using a thermal gradient tester (manufactured by Toyo Seiki Co., Ltd.) commonly used by those skilled in the art. Color density at the time of exposure (Macbeth densitometer RD-914)
Means the temperature at which reaches 0.2. Further, the activation temperature of the heat-sensitive adhesive layer means a temperature at which tackiness starts to develop when the heat-sensitive adhesive layer is heated under the same conditions as described above.

Further, by providing a heat insulating layer between the support and the heat-sensitive coloring layer and / or between the support and the heat-sensitive adhesive layer, the color sensitivity can be improved by efficiently utilizing the heat energy of the thermal head. The improvement and the improvement of the activation efficiency of the heat-sensitive adhesive layer on the back surface make it possible to increase the temperature difference between the activation temperature of the heat-sensitive adhesive and the color development start temperature of the heat-sensitive coloring layer. Examples of the heat insulating layer in the present invention include a heat insulating layer using a thermoplastic resin as a shell and using fine hollow particles having a hollowness of 30% or more and a foaming heat insulating layer using a foamable filler.

The fine hollow particles having a shell made of a thermoplastic resin used in the present invention contain air or other gas therein, and are already in a foamed state. Although those having a diameter of 0.4 to 20 μm can be used, those having a diameter of 0.5 to 10 μm are more preferable. If the average particle diameter (particle outer diameter) is smaller than 0.4 μm, there is a problem in production such as difficulty in obtaining an arbitrary hollowness, and there is a problem in cost. Larger particles have lower surface smoothness after coating and drying, and thus lower adhesion to the thermal head, resulting in poor dot reproducibility and a reduced sensitivity improving effect. Therefore,
Such a particle distribution desirably has a particle diameter within the above range and a uniform distribution spectrum with little variation.

The fine hollow particles having a shell of a thermoplastic resin used in the present invention may have a hollowness of 30% or more, and more preferably 50% or more. When the hollowness is less than 30%, the heat insulating property is insufficient.
Thermal energy from the thermal head is released to the outside of the thermosensitive recording material through the support, and the color sensitivity is not improved.
Further, the heat-insulating effect of heat energy of heat conversion by light irradiation is small, the effect of activating the heat-sensitive adhesive is inferior, and the expression of adhesiveness is weakened. Here, the hollowness is a ratio of the outer diameter to the inner diameter of the hollow particles, and is represented by the following equation.

(Equation 1) The fine hollow particles used in the present invention have a shell made of a thermoplastic resin as described above, and the resin is preferably a copolymer resin mainly containing vinylidene chloride and acrylonitrile.

In order to provide a non-foamable heat-insulating layer of a support, the above-mentioned fine hollow particles are dispersed in water together with a binder such as a known water-soluble polymer or aqueous polymer emulsion, and this is coated on the surface of the support. , Dried.
In this case, the coating amount of the fine hollow particles is at least 1 g, preferably about ^{2 to} 15 g per 1 m ² of the support,
The amount of the binder resin applied may be such that the intermediate layer is strongly bonded to the support, and is usually 2 to 50% by weight based on the total amount of the hollow microparticles and the binder resin.

In the present invention, the binder used for forming the non-foamable heat insulating layer is appropriately selected from conventionally known water-soluble polymers and / or aqueous polymer emulsions. Specific examples thereof include, as water-soluble polymers, for example, polyvinyl alcohol, starch and derivatives thereof, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose,
Cellulose derivatives such as ethyl cellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide / acrylate copolymer, acrylamide / acrylate / methacrylic acid terpolymer, styrene / maleic anhydride copolymer alkali salt, isobutylene / Maleic anhydride copolymer alkali salt, polyacrylamide,
Examples include sodium alginate, gelatin, casein and the like. Further, as an aqueous polymer emulsion, for example, latex such as styrene / butadiene copolymer, styrene / butadiene / acrylic copolymer, vinyl acetate resin,
Emulsions such as vinyl acetate / acrylic acid copolymer, styrene / acrylic ester copolymer, acrylate resin, polyurethane resin and the like can be mentioned. In the non-foamable heat-insulating layer of the present invention, the fine hollow particles,
If necessary, auxiliary additives commonly used in this type of heat-sensitive recording material, such as a heat-fusible substance and a surfactant, can be used together with the (optionally pigment) and the binder. In this case, specific examples of the heat-fusible substance include various substances described later in relation to the components of the thermosensitive coloring layer.

The foamable filler used in the present invention is a hollow plastic filler containing a thermoplastic resin as a shell and a foaming agent of a low boiling point solvent therein, and foams by heating. Such foamed plastic fillers are conventionally known, and various types are applied. Regarding the particle diameter, in the case of an unfoamed state, 2 to 50 μm is used.
m, preferably 5 to 20 μm.
It is 0 to 100 μm, preferably 10 to 50 μm. Examples of the thermoplastic resin serving as a shell of the plastic filler include polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyacrylate, polyacrylonitrile, polybutadiene, and a copolymer thereof. Further, as the foaming agent contained in the shell, propane, butane and the like are generally used.

In order to form a foamed layer on the support, the foamable plastic filler described above is coated and dried on the support together with the binder, and then a hot plate is brought into close contact with the coated surface and the plastic filler is heated. What is necessary is just to foam. The coating amount of the plastic filler is at least 1 g, preferably ² to 5 g, as an unfoamed filler per 1 m ² of the support.
It is about. The amount of the binder used may be such that the foamed layer is strongly bonded to the support, and usually 5 to 50% by weight based on the total amount of the unfoamed filler and the binder.
It is. The heating foaming temperature is a temperature at which the thermoplastic resin constituting the shell of the filler is softened. The expansion ratio is
Usually, it is about 2 to 4 times, preferably about 2 to 3 times, and is appropriately selected so as to achieve the desired foaming.

As described above, since the surface of the foam layer formed on the support is considerably uneven, it is necessary to smooth the surface by calendering after forming the foam layer (after heating and foaming). Preferably, if necessary, one or more undercoat layers may be provided on the surface or lower surface of the foam layer. In the heat-insulating layer of the present invention, if necessary, an auxiliary additive component commonly used in this type of heat-sensitive recording material, for example, a thermosetting material, together with the fine hollow particles or the porous pigment or the foamable filler and the binder. A fusible substance, a surfactant and the like can be used in combination. In this case, specific examples of the heat-fusible substance include various substances described later in relation to the heat-sensitive recording layer components.

Next, a leuco dye as a color former used in the thermosensitive coloring layer of the thermosensitive recording label of the present invention may be used alone or as a mixture of two or more kinds. What is applied to the material is arbitrarily applied, and for example, a leuco compound of a dye such as a triphenylmethane type, a fluoran type, a phenothiazine type, an auramine type, a spirovirane type, or an indolinophthalide type is preferably used. Specific examples of such leuco dyes include, for example, those shown below.
3,3-bis (p-dimethylaminophenyl) -phthalide, 3,3-bis (p-dimethylaminophenyl) -6
-Dimethylaminophthalide (also known as crystal violet lactone), 3,3-bis (p-dimethylaminophenyl) -6-diethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) -6-chlorophthalide, 3, 3-bis (p-dibutylaminophenyl) phthalide, 3-cyclohexylamino-6-chlorofluoran, 3-dimethylamino-5,7-dimethylfluoran, 3-diethylamino-7-chlorofluoran, 3-
Diethylamino-7-methylfluorane, 3-diethylamino-7,8-benzfluoran, 3-diethylamino-6-methyl-7-chlorofluoran, 3- (N-p
-Tolyl-N-ethylamino) -6-methyl-7-anilinofluoran, 3-pyrrolidino-6-methyl-7-anilinofluoran, 2- [N- (3'-trifluoromethylphenyl) amino ] -6-diethylaminofluoran, 2- [3,6-bis (diethylamino) -9- (o
-Chloroanilino) lactam xanthylbenzoate], 3
-Diethylamino-6-methyl-7- (m-trichloromethylanilino) fluoran, 3-diethylamino-7
-(O-chloroanilino) fluoran, 3-di-n-butylamino-7- (o-chloroanilino) fluoran,
3-N-methyl-N, n-amylamino-6-methyl-
7-anilinofluoran, 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3- (N, N -Diethylamino) -5-methyl-7- (N, N-dibenzylamino) fluoran, benzoylleucomethylene blue, 6'-chloro-8'-
Methoxy-benzoindolinose pyropyran, 6'-promo-3'-methoxy-benzoindolinose pyropyran, 3- (2'-hydroxy-4'-dimethylaminophenyl) -3- (2'-methoxy-5'-chloro Phenyl) phthalide, 3- (2'-hydroxy-4'-dimethylaminophenyl) -3- (2'-methoxy-5'-nitrophenyl) phthalide, 3- (2'-hydroxy-
4'-diethylaminophenyl) -3- (2'-methoxy-5'-methylphenyl) phthalide, 3- (2'-methoxy-4'-dimethylaminophenyl) -3- (2 '
-Hydroxy-4'-chloro-5'-methylphenyl)
Phthalide, 3- (N-ethyl-N-tetrahydrofurfuryl) amino-6-methyl-7-anilinofluoran,
3-N-ethyl-N- (2-ethoxypropyl) amino-6-methyl-7-anilinofluoran, 3-N-methyl-N-isobutyl-6-methyl-7-anilinofluoran, 3- Morpholino-7- (N-propyl-trifluoromethylanilino) fluoran, 3-pyrrolidino-7
-M-trifluoromethylanilinofluoran, 3-diethylamino-5-chloro-7- (N-benzyl-trifluoromethylanilino) fluoran, 3-pyrrolidino-7- (di-p-chlorophenyl) methylamino Fluoran, 3-diethylamino-5-chloro-7- (α-phenylethylamino) fluoran, 3- (N-ethyl-
p-Toluidino) -7- (α-phenylethylamino)
Fluoran, 3-diethylamino-7- (o-methoxycarbonylphenylamino) fluoran, 3-diethylamino-5-methyl-7- (α-phenylethylamino) fluoran, 3-diethylamino-7-piperidinofluoran, 2 -Chloro-3- (N-methyltoluidino) -7- (pn-butylanilino) fluoran, 3
-(N-methyl-N-isopropylamino) -6-methyl-7-anilinofluoran, 3-di-n-butylamino-6-methyl-7-anilinofluoran, 3,6-bis (dimethyl Amino) fluorenespiro (9,3 ')-
6'-dimethylaminophthalide, 3- (N-benzyl-
N-cyclohexylamino) -5,6-benzo-7-α
-Naphthylamino-4'-bromofluorane, 3-diethylamino-6-chloro-7-anilinofluoran, 3
-Diethylamino-6-methyl-7-mesitidino-
4 ', 5'-benzofluoran, 3-N-methyl-N-
Isopropyl-6-methyl-7-anilinofluoran,
3-N-ethyl-N-isoamyl-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-
7- (2 ', 4'-dimethylanilino) fluoran and the like.

As the color developer used in the heat-sensitive coloring layer of the label for heat-sensitive recording of the present invention, various compounds having an electron-accepting property or a oxidizing agent for forming a color when the leuco dye is contacted are applied. Such materials are conventionally known, and specific examples thereof include the following. 4,
4'-isopropylidene diphenyl, 4,4'-isopropylidenebis (o-methylphenol), 4,4 '
-Sec-butylidenebisdenol, 4,4'-isopropylidenebis (2-tert-butylphenol),
Zinc p-nitrobenzoate, 1,3,5-tris (4-t
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, monobenzyl phthalate monocalcium salt, 4,4'-cyclohexylidenediphenol, 4,4'-isopropylidenebis (2-
Chlorophenol), 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 4,4'-
Butylidenebis (6-tert-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-pendyloxy-4'-hydroxydiphenylsulfone, 4,4 '
-Diphenol sulfoxide, isopropyl P-hydroxybenzoate, benzyl P-hydroxybenzoate, benzyl protocatechulate, 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, bis- (4-hydroxyphenyl)
Benzyl 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, zinc 1-acetyloxy-2-naphthoate, zinc 2-acetyloxy-1-naphthoate, zinc 2-acetyloxy-3-naphthoate, α, α-bis (4-hydroxyphenyl)- α-methyltoluene, an antipyrine complex of zinc thiocyanate, tetrabromobisphenol A,
Tetrapromobisphenol S, 4,4'-thiobis (2-methylphenol), 4,4'-thiobis (2-
Chlorophenol) and the like.

In the present invention, a protective layer can be provided on the thermosensitive coloring layer. The protective layer used in the present invention is important as a component of the present invention for improving the transparency, chemical resistance, water resistance, rub resistance, light resistance, and head matching of the thermal recording label with respect to the thermal head. . The protective layer of the present invention includes a film formed mainly 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.

As such a resin, besides a water-soluble resin,
Aqueous emulsion, hydrophobic resin and ultraviolet curable resin,
Further, an electron beam curable resin is included. Specific examples of the water-soluble resin include, for example, polyvinyl alcohol, modified polyvinyl alcohol, cellulose derivatives (methyl cellulose, methoxy cellulose, hydroxy cellulose, 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 / Examples include a polyacrylamide block copolymer, a melamine-formaldehyde resin, and a urea-formaldehyde resin.

The resin or hydrophobic resin for the aqueous emulsion includes, for example, polyvinyl acetate, polyurethane, styrene / butadiene copolymer, styrene / butadiene / acrylic copolymer, polyacrylic acid, polyacrylate, Examples thereof include vinyl chloride / vinyl acetate copolymer, polybutyl methacrylate, polyvinyl butyral, polyvinyl acetal, ethyl cellulose, and ethylene / vinyl acetate copolymer. Also, copolymers of these resins and silicon segments are preferably used. These may be used alone or as a mixture, 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 is a monomer, oligomer or prepolymer which undergoes a polymerization reaction upon irradiation with ultraviolet light and cures to become a resin, and various known resins can be used. Although the type of the electron beam-curable resin is not particularly limited, particularly preferred electron beam-curable resins are 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 a component.

In order to improve head matching, inorganic and organic fillers and lubricants can be added to these protective layers as long as the surface smoothness is not reduced. The particle size of the filler in the present invention is preferably 0.3 μm or less. As the pigment in this case, the oil absorption is 30 ml / 100 g.
As described above, a product having a weight of preferably 80 ml / 100 g or more is selected. As these inorganic and / or organic pigments, one or more of pigments commonly used in this type of heat-sensitive recording medium can be selected. Specific examples thereof 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, Organic pigments such as styrene / methacrylic acid copolymer and polystyrene resin can be mentioned.

The coating method of the protective layer is not particularly limited, and it can be applied by a conventionally known method.

The preferred 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 function of the protective layer such as the preservability and head matching of the label for thermal recording is insufficient, and if it is too thick, the thermal sensitivity of the label for thermal recording decreases and the cost is reduced. Disadvantageous.

When a heat-sensitive recording material is obtained according to the present invention, if necessary, together with a leuco dye and a developer, additional components commonly used in this type of heat-sensitive recording material, such as fillers, surfactants, lubricants, A pressure coloring inhibitor or the like can be used in combination as long as the coloring property of the recording medium is not impaired. in this case,
Fillers such as calcium carbonate, silica, zinc oxide,
Inorganic fine powders such as titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, kaolin, talc, surface-treated calcium and silica, urea-formalin resin, styrene / methacrylic acid copolymer, polystyrene Resin, organic fine powders such as vinyldene chloride resin, and examples of the lubricant include higher fatty acids and metal salts thereof, higher fatty acid amides, higher fatty acid esters, animal, vegetable, mineral or petroleum-based lubricants. Various waxes are included.

As the heat-sensitive adhesive label of the present invention, in addition to the above-mentioned heat-sensitive recording label having a heat-sensitive color-developing layer, a heat-sensitive transfer (melt transfer) ribbon receiving label, an ink jet receiving label, and a sublimation transfer ribbon receiving label. And the like.

Hereinafter, representative heat-sensitive adhesive labels used in the present invention will be described. (A) Label for Thermal Recording The label for thermal recording of the present invention is generally paper, synthetic paper,
A thermosensitive layer having a leuco dye and a developer, an undercoat layer provided as necessary, a thermosensitive coloring layer comprising a protective layer, and a delayed tack on the other surface of the base material such as a film such as PET. It has a configuration composed of a heat-sensitive adhesive layer having an adhesive, and the details thereof have been described in the present specification, and thus are omitted here.

(B) Thermal transfer (melt transfer) receiving label for ribbon The principle of the thermal transfer (melt transfer) method is that a heat-meltable ink (monochrome, color) solid at room temperature on a substrate having a thickness of several μm. Is softened and melted by the heat of the thermal head and transferred to the receiving paper, with the thermal transfer ribbon coated with a thickness of several μm.
An image is formed. Generally, the receiving label for the thermal transfer (melt transfer) ribbon has a configuration in which a plain paper or a coated paper is used as a base material and a heat-sensitive adhesive layer is provided on the back surface. The transfer surface of the back surface, that is, the hot-melt receiving surface is generally a surface having relatively high smoothness in which inorganic fillers such as clay and calcium carbonate are internally added or coated. If it has a function, it is not necessarily limited to these.

(C) Receiving label for ink-jet The principle of the ink-jet method is that, in a printer having a head in which a large number of nozzles are arranged at high density, ink (monochrome, color) containing a dye is ejected from the nozzles onto a receiving paper. To form an image. This ink-jet receiving label generally has a configuration in which plain paper or coated paper is used as a base material, and an ink-absorbing layer provided as needed on the front surface, and a heat-sensitive adhesive layer on the back surface, respectively. I have. Ink jet inks generally use a wetting agent to prevent nozzle clogging. However, since the drying of the ink is deteriorated by the influence of the wetting agent, as the receiving paper, non-size paper, special paper such as coated paper having fine silica or a water-soluble binder or the like coated on the paper surface is generally used. Although it is used, it is not necessarily limited to this, and plain paper such as acidic paper and neutral paper, and a film for an OHP sheet can be used.

(D) Receiving Label for Sublimation Transfer Ribbon The principle of the sublimation transfer method is that of a sublimation dye (monochrome, color).
The transfer film coated with the dye layer containing the dye is transferred, absorbed and fixed to the image receiving layer of the receiving paper on which the special image receiving layer is coated with the sublimation dye by the heat of the thermal head. This sublimation transfer ribbon receiving label generally has a structure in which a special image receiving layer having a highly smooth and high gloss surface, that is, a sublimation dye image receiving layer is provided on an image receiving paper substrate. As the image receiving paper substrate, the entire substrate must have appropriate heat resistance and homogeneity, and the surface must be imparted with smoothness and flexibility. In general, synthetic paper having a thickness of 100 to 200 μm or A PET film provided with a flexible white hiding layer is used. In addition, the image receiving layer requires dyeing properties, color reproducibility, dye fixability, releasability from the dye layer, and the like. Generally, a thermoplastic polyester resin is used. Further, for the purpose of preserving the image and preventing fusion with the dye layer, other resins, inorganic particles, metal complexes, releasable materials and the like are added, and the layer is cured.

Accordingly, the support used in the present invention is not particularly limited, and other than paper, polyester films such as polyethylene terephthalate and polybutylene terephthalate, cellulose derivative films such as cellulose triacetate, and polyolefin films such as polypropylene and polyethylene. , A polystyrene film or a film obtained by laminating them.

[0039]

Next, the present invention will be described in more detail by way of examples. In addition, all the parts and% shown below are based on weight.

Example 1 [Solution A] 3-butylamino-6-methyl-7-anilinofluoran 20 parts Polyvinyl alcohol 10% aqueous solution 20 parts Water 60 parts [Solution B] developer dispersion 4-hydroxy- 4'-isopropoxydiphenyl sulfone 10 parts Polyvinyl alcohol 10% aqueous solution 25 parts Calcium carbonate 15 parts Water 50 parts Each of the mixtures having the above composition has an average particle size of 2.0.
μm or less using a sand mill.
Liquid] and [Liquid B]. Next, [Solution A] and [Solution B]
Was mixed and stirred so that the weight ratio of [A solution]: [B solution] = 1: 8 to obtain a coating solution [C solution] for forming a thermosensitive coloring layer. [D liquid] Micro hollow particle dispersion (solid content 32%, average particle diameter 5 μm, hollowness 92%) 30 parts (copolymer resin mainly composed of vinylidene chloride-acrylonitrile) Styrene / butadiene copolymer latex (solid 5 parts Water 60 parts (D liquid) having the above composition was stirred and dispersed to prepare a non-foamable heat-insulating layer liquid, which was dried on the surface of high quality paper and weighed 5%.
g / m ² and dried to obtain paper coated with a non-foamable heat-insulating layer. (C solution) is applied and dried on the non-foamable heat-insulating layer coated paper so that the weight becomes 5 g / m ^2, and the Beck smoothness is 600 to 70.
Super calender treatment was performed so that the time became 0 second, to obtain a paper coated with a thermosensitive coloring layer. [E Solution] MMA / butadiene copolymer 15 parts by weight (manufactured by Takeda Pharmaceutical Co., Ltd .: 2M-36, solid content: 47.5%) Styrene / acrylic copolymer 15 parts by weight (manufactured by Showa Polymer: Polysol AT-2040, Rosin S <sp = 125 ° C.> 10 parts by weight (Arakawa Kagaku: Superester E-730-55, solids content: 55%) Dicyclohexyl phthalate 20 parts by weight Amine dispersant 2 parts by weight Water 38 parts by weight 30 parts by weight, 3 parts by weight, 2 parts by weight of dicyclohexyl phthalate, [A liquid E]
Same as [Solution E] except that the mixture was 7 parts by weight. A heat-sensitive adhesive dispersion [Solution E] obtained by dispersing a mixture having the above composition using a ball mill so that the average particle size becomes 3.0 μm or less. ] And [Liquid F] on the back of the paper coated with the thermosensitive coloring layer, [Liquid E] after drying and weighing 15 g / m ² ,
[F liquid] was dried and then sequentially laminated and dried so as to have a weight of 10 g / m ² to obtain a heat-sensitive adhesive label.

Example 2 A heat-sensitive adhesive label of Example 2 was obtained in the same manner as in Example 1 except that the non-foamed heat insulating layer was removed from the heat-sensitive adhesive label of Example 1.

Example 3 [Solution G] 4-hydroxy-4-isopropoxydiphenyl sulfone 10 parts Di (p-methylbenzyl) oxalate 3 parts Polyvinyl alcohol 10% aqueous solution 25 parts Calcium carbonate 15 parts Water 47 parts From the above composition Mixtures having an average particle size of 2.0
It was dispersed using a sand mill so as to have a particle size of not more than μm to prepare a developer [Solution G]. A heat-sensitive adhesive label of Example 3 was obtained in the same manner as in Example 1 except that [G solution] was used instead of [B solution] of Example 1.

Example 4 The heat sensitivity of Example 4 was changed in the same manner as in Example 3 except that p-benzylbiphenyl was used instead of di (p-methylbenzyl) oxalate in [Solution G] of Example 3. An adhesive label was obtained.

Example 5 MMA / butadiene copolymer of [Solution E] and [Solution F] of Example 1 (manufactured by Takeda Pharmaceutical: 2M-36, solid content: 47.5)
%) Was used in the same manner as in Example 1 except that a styrene / acrylic copolymer (manufactured by Showa Polymer: Polysol AT-2040, solid content: 40%) was used in place of%.

Example 6 Example 6 was repeated except that styrene / acrylic copolymer (manufactured by Showa Polymer: Polysol AT-2040, solid content: 40%) was used instead of dicyclohexyl phthalate in [Solution E] of Example 1. A sample of Example 6 was obtained in the same manner as in Example 1.

Example 7 MMA / butadiene copolymer of [Solution E] and [Solution F] of Example 1 (manufactured by Takeda Pharmaceutical: 2M-36, solid content: 47.5)
%) And a styrene / acrylic copolymer (manufactured by Showa Polymer:
The same procedure as in Example 1 was carried out except that ethylene / vinyl acetate copolymer (manufactured by Mitsui Petrochemical: Chemipearl V-100, solid content: 40%) was used instead of Polysol AT-2040, solid content: 40%. Thus, a sample of Example 7 was obtained.

Example 8 The parts by weight of dicyclohexyl phthalate, amine dispersant and water of [Solution F] of Example 1 were 80 parts by weight, 8 parts by weight and 7 parts by weight, respectively.
A sample of Example 8 was obtained in the same manner as in Example 1 except that the amount was 2 parts by weight.

Comparative Example 1 10 parts by weight, 1 part by weight, 4 parts by weight of dicyclohexyl phthalate, amine dispersant and water of [Solution F] of Example 1
A sample of Comparative Example 1 was obtained in the same manner as in Example 1 except that the amount was 9 parts by weight.

COMPARATIVE EXAMPLE 2 Without coating [Solution F] of Example 1, [Solution E] was dried and then applied and dried to a weight of 25 g / m ² after drying. A sample of Comparative Example 2 was obtained in the same manner as in Example 1 except that was formed.

COMPARATIVE EXAMPLE 3 Without applying [Solution E] of Example 1, [Solution F] was dried and then coated and dried to a weight of 25 g / m ² after drying. A sample of Comparative Example 3 was obtained in the same manner as in Example 1 except that the sample was formed.

Regarding the linerless thermosensitive recording label obtained as described above, the dynamic color density of the heat-sensitive coloring layer, the adhesive force of the heat-sensitive adhesive layer on the back surface due to light irradiation, and the heat-sensitive coloring layer surface and the heat-sensitive layer The following test was conducted on the blocking resistance when the layer was brought into contact with the adhesive layer. <Dynamic color density> Using a thermal printing tester having a thin film head manufactured by Matsushita Electronic Components Co., Ltd., a head power of 0.60 W /
dot, one line recording time 10 msec / 1 line,
Printing was performed at a scanning line density of 8 × 7: 7 dots / mm with a pulse width of 0.4 and 0.5 msec, and the printing density was measured with a Macbeth densitometer RD-914. <Tackiness and background density due to light irradiation> The label for thermal recording obtained as described above was subjected to 3M Transparency.
-A sample activated by irradiation with light is adhered to the adherend (vinyl chloride wrap, polyethylene wrap) so that light from a Maker (1350 W, halogen lamp) is irradiated to the heat-sensitive adhesive layer on the back surface. ), And the adhesive strength was evaluated according to the following rank. <Evaluation Criteria> 強 く: Strongly adhered ○: Adhered △: Slightly adhered ×: Not adhered <Blocking resistance> The heat-sensitive coloring layer and the heat-sensitive adhesive layer of the same sample were brought into contact with each other to obtain 2 kg / cm ² . 40 by pressure
After testing at 24 ° C. and 90% RH for 24 hours, the sample was peeled off after standing at room temperature, and the blocking resistance at that time was evaluated according to the following ranks. <Evaluation Criteria> ブ ロ ッ キ ン グ: No blocking occurred (no peeling sound) ：: No blocking occurred (no peeling sound) Δ: Slight blocking occurred ×: Overall blocking occurred The measurement results are shown in Table 1 below.

[0052]

[Table 1]

[0053]

According to the heat-sensitive adhesive label of the present invention, the heat-sensitive adhesive layer has a two-layer structure, and a thermoplastic resin,
By containing at least one of a tackifier and a solid plasticizer, and making the solid plasticizer content of the second adhesive layer higher than that of the first adhesive layer, the adhesive force to each adherend And has excellent blocking resistance in a wound state. In addition, a heat-sensitive adhesive label using a styrene / acrylic copolymer and / or an acrylic / butadiene copolymer as the thermoplastic resin further has an increased adhesive strength to vinyl chloride wrap and polyethylene wrap,
In addition, the blocking resistance can be improved.

Claims (6)

[Claims] 1. A first heat-sensitive adhesive layer containing at least one of a thermoplastic resin, a tackifier and a solid plasticizer, and a second heat-sensitive adhesive layer sequentially laminated on a support. In a heat-sensitive adhesive label having a heat-sensitive adhesive layer,
A heat-sensitive adhesive label, wherein the content of the solid plasticizer in the second heat-sensitive adhesive layer is higher than the content of the solid plasticizer in the first heat-sensitive adhesive layer. 2. The heat-sensitive adhesive label according to claim 1, wherein the heat-sensitive adhesive layer contains a styrene / acrylic copolymer and / or an acrylic / butadiene copolymer as the thermoplastic resin. . 3. The heat-sensitive adhesive label according to claim 1, wherein a heat-sensitive coloring layer containing a leuco dye and a color developer is provided on the other side of the heat-sensitive adhesive layer of the heat-sensitive adhesive label. Heat-sensitive adhesive label. 4. The method according to claim 1, wherein the activation temperature of the heat-sensitive adhesive layer of the heat-sensitive adhesive label is lower by at least 10 ° C. than the color-forming start temperature of the heat-sensitive coloring layer. Item 6. The heat-sensitive adhesive label according to Item 3. 5. The heat-sensitive adhesive label provided with the heat-sensitive coloring layer, wherein a heat insulating layer is provided between the support and the heat-sensitive coloring layer and / or between the support and the heat-sensitive adhesive layer. 4. The heat-sensitive adhesive label according to claim 1, 2 or 3. 6. The heat insulating layer according to claim 1, wherein the heat insulating layer is a heat insulating layer mainly composed of fine hollow particles having a hollowness of 30% or more and having a shell of a thermoplastic resin. Or the heat-sensitive adhesive label according to claim 4.