JP2001215880A - Polyolefin-base shrink label - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a shrink label which has excellent strength of stiffness, gloss, natural shrinkage and fittability to an adherend in thermal shrinkage, allows solvent sealing and is free of curling in printing, the blocking occurring in a residual solvent and the problem of an organic solvent smell. SOLUTION: A base film of the polyolefin-based shrink label provided with a printing layer on at least one surface of the base film comprises a uniaxially or biaxially oriented polyolefin-based film composed of a central layer consisting of a propylene-based polymer and surface layers consisting of an amorphous cyclic olefinic polymer laminated on both surfaces of this central layer. The printing layer is formed of water-based ink. The printing layer may be formed by the water-based ink containing, for example, an alkaline-soluble acrylic resin and water as the essential components of a vehicle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shrink label to be attached to a container such as a plastic container or a glass container by heat shrinkage.

[0002]

2. Description of the Related Art Conventionally, as a shrink label to be attached to a plastic container such as a container for soft drinks or a container for cup noodles (instant noodles in cups), a non-halogenated oriented polypropylene (OPP) film is used as a base film. Labels are used. However, conventional shrink labels made of a heat-shrinkable OPP film have advantages such as low specific gravity and relatively low cost, but they are not always satisfactory in terms of stiffness and gloss, and they are not natural. There are problems such as large shrinkage, poor fit during heat shrinkage, and the inability to perform solvent sealing.

The inventors of the present invention have studied methods for solving these problems, and as a result, have found that a base film of a shrink label is made of a central layer made of a propylene polymer and an amorphous layer laminated on both sides of the central layer. When it is composed of a surface layer made of a functional cyclic olefin polymer, it has been found that the strength of stiffness, gloss, natural shrinkage, fit during heat shrinkage are improved, and sealing with a solvent is possible. . However, when printing on such a base film using a normal organic solvent-based gravure ink, the label curls or the amount of solvent remaining on the label increases,
Problems tend to occur after printing, such as blocking or strong organic solvent odor.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide excellent seal strength, luster, natural shrinkage, and good fit to an adherend during heat shrinkage, and to provide a solvent seal. Moreover, it is an object of the present invention to provide a shrink label free from the problems of curling during printing and the problem of organic solvent odor due to curl and residual solvent.

[0005]

Means for Solving the Problems The inventors of the present invention have made intensive studies to achieve the above object, and as a result, have formed a base film from a polyolefin-based laminated film having a specific layer structure, and formed a base film on the base film. When a printing layer is formed using an aqueous ink, not only is it possible to obtain excellent gloss and fit, but also it is possible to seal the center with a solvent, etc., and to prevent curling and blocking caused by a residual solvent during printing. Heading, the present invention has been completed.

That is, the present invention relates to a shrink label having a printing layer provided on at least one surface of a base film, wherein the base film has a center layer made of a propylene-based polymer and both surfaces of the center layer. Provided is a polyolefin-based shrink label comprising a monoaxial or biaxially oriented polyolefin-based film composed of a laminated surface layer made of an amorphous cyclic olefin-based polymer, and wherein the printing layer is formed of an aqueous ink. .

As the base film, for example, 8
A film having a heat shrinkage of 20% or more in the main orientation direction X when immersed in warm water of 0 ° C. for 10 seconds can be used. The printing layer can be formed of, for example, an aqueous ink containing an alkali-soluble acrylic resin and water as main components of the vehicle. The polyolefin-based shrink label may be formed in a cylindrical shape such that the main orientation direction X is the circumferential direction.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings as necessary. FIG. 1 is a schematic cross-sectional view showing an example of the polyolefin-based shrink label of the present invention, and FIG. 2 is a perspective view showing a state when the shrink label of FIG. 1 is mounted on an object to be mounted (cup-shaped container).

The polyolefin shrink label 1 shown in FIG. 1 comprises a base film 2 and a printing layer 3 provided on one surface of the base film 2. And
The base film 2 comprises a central layer 4 made of a propylene-based polymer, and surface layers 5 and 5 made of an amorphous cyclic olefin-based polymer laminated on both sides of the central layer 4. It consists of an axially oriented polyolefin-based film.

As the propylene polymer constituting the central layer 4 of the base film 2, various polymers containing propylene as a constituent monomer can be used, and a typical example thereof is an ethylene-propylene random copolymer. Can be The ethylene content in the ethylene-propylene random copolymer is, for example, 3 to 5% by weight, preferably 3.5.
It is about 4.5% by weight. The ethylene-propylene random copolymer can be obtained by a conventional polymerization method, but a commercially available product can also be used. Another typical example of the propylene-based polymer is a terpolymer of ethylene, propylene and butene.

The center layer 4 may contain, in addition to the propylene polymer, at least one resin selected from a hydrogenated petroleum resin and a hydrogenated terpene resin, if necessary. By including such a resin in the center layer 4, transparency, stiffness, heat shrinkability at low temperatures, and the like can be improved. The hydrogenated petroleum resin is a resin obtained by hydrogenating an aromatic petroleum resin, and the hydrogenated terpene resin is a resin obtained by hydrogenating a terpene resin such as a terpene resin or an aromatic modified terpene resin. And commercial products can be used.

The amount of the resin to be used can be appropriately selected within a range not to impair the film-forming property and the like. ), Preferably about 10 to 25 parts by weight. The center layer 4 may further contain a small amount of another polymer, if necessary. The thickness of the center layer 4 is, for example, about 10 to 100 μm, and preferably about 15 to 50 μm.

The surface layers 5, 5 are formed of an amorphous cyclic olefin polymer. Amorphous cyclic olefin polymers include (A) ethylene, propylene, 1-butene, 1-
A copolymer of an α-olefin such as hexene and 4-methyl-1-pentene and at least one cyclic olefin (hereinafter may be referred to as “cyclic olefin copolymer”), and (B) a cyclic olefin Ring-opening polymers or hydrogenated products thereof are included.

Cyclic in the polymers (A) and (B)
Examples of the olefin include bicyclo [2.2.1].
Hept-2-ene (norbornene), tetracyclo
[4.4.0.1^2,5. 1^7,10] -3-dodecene, hex
Sacyclo [6.6.1.1^3,6. 1 ^10,13. 0^2,7. 0
^9,14] -4-heptadecene, octacyclo [8.8.
0.1^{2, 9}. 1^4,7. 1^11,18. 1^13,16. 0^3,8.
0^12,17] -5-docosene, pentacyclo [6.6.
1.1^3,6. 0^2,7. 0^9,14] -4-Hexadecene, hep
Tacyclo-5-icosene, heptacyclo-5-hemico
Sen, tricyclo [4.3.0.1^{2, Five}] -3-Dece
, Tricyclo [4.3.0.1^2,5] -3-Undesse
Pentacyclo [6.5.1.1^3,6. 0^2,7.
0^9,14] -4-pentadecene, pentacyclopentadeca
Diene, pentacyclo [4.7.0.1^2,5. 0^8,13.
1^9,12] -3-pentadecene, nonacyclo [9.10.
1.1^4,7. 1^13,20. 1^15,18. 0^{Two ,Ten}. 0^12,21. 0
^14,19Polycyclic cyclic olefins such as -5-pentacocene
And the like. These cyclic olefins have
S such as methoxycarbonyl and ethoxycarbonyl groups
Alkyl group such as ter group, methyl group, haloalkyl group,
It may have a substituent such as a cyano group or a halogen atom.
No.

The cyclic olefin copolymer (A) is prepared by, for example, reacting the α-olefin and the cyclic olefin in a hydrocarbon solvent such as hexane, heptane, octane, cyclohexane, benzene, toluene, xylene, etc. with a so-called Ziegler catalyst. It can be obtained by polymerization using a catalyst such as a metallocene catalyst. Such a cyclic olefin copolymer (A) is commercially available, and for example, trade name “Apel” (manufactured by Mitsui Chemicals, Inc.) can be used.

The ring-opened polymer of cyclic olefin or its hydrogenated product (B) is, for example, subjected to metathesis polymerization (ring-opening polymerization) using a molybdenum compound or a tungsten compound as a catalyst. The polymer can be produced by further hydrogenating the obtained polymer. Such a polymer (B) is commercially available, and for example, trade name “ARTON” (manufactured by Nippon Synthetic Rubber Co., Ltd.), trade name “ZEONEX” (manufactured by Nippon Zeon Co., Ltd.) and the like can be used.

A preferred amorphous cyclic olefin polymer is the above-mentioned cyclic olefin copolymer (A). Among them, ethylene and bicyclo [2.2.1] hept-2-ene (norbornene) or tetracyclo [4.4.0.1
^2,5 . Copolymers with [ ^1,7,10 ] -3-dodecene are preferred, and those having an ethylene content in the range of 60 to 85 mol% (particularly 70 to 80 mol%) are particularly preferred.

The surface layers 5 and 5 may be formed of one or more of the above-mentioned amorphous cyclic olefin polymers.
Further, other polymers may be contained in a small amount as required.

The thickness of each of the surface layers 5 and 5 is, for example, about 0.5 to 10.0 μm, preferably 1.0 to 10.0 μm.
It is about 5.0 μm. The ratio of the total thickness of both surface layers 5 and 5 to the thickness of base film 2 is, for example, 3 to
It is 50%, preferably about 5 to 30%. If this ratio is less than 3%, the state is likely to be relaxed after heat shrinkage. In addition, since the amorphous cyclic olefin polymer is relatively expensive, the ratio is preferably set to 30% or less.

The surface of the surface layer 5 on the side of the printing layer 3 may be subjected to a conventional surface treatment such as corona discharge treatment, plasma treatment or flame treatment, or an anchor coat treatment in order to improve printability. . Known or commonly used anchor coating agents for aqueous printing inks can be used as the anchor coating agent used in the anchor coating treatment. Further, as the anchor coating agent, an anchor coating agent containing an acrylic copolymer resin and a nitrogen atom-containing polymer compound can be used.

The acrylic copolymer resin may be any resin having an adhesive force to an olefin resin.
For example, homo- or copolymers of acrylic monomers such as (meth) acrylic acid and (meth) acrylic acid ester, or the acrylic monomers, styrene monomers, carboxyl group-containing monomers, acid anhydride group-containing monomers, and chlorides Examples thereof include copolymers with other monomers such as vinyl, olefin, and vinyl esters.

As the above-mentioned nitrogen-containing polymer compound,
For example, (i) a high molecular weight amine compound having an amino group (including a hydrazino group) in the main chain or side chain of the polymer;
(Ii) a polymer compound having a cationic quaternary ammonium base in the side chain of the polymer, (iii) a polymer amide compound having an amide group in the side chain, and (iv) a polyamide having a main chain formed by an amide bond. Resins.

In the shrink label of the present invention, a lubricant, a filler, a heat stabilizer, an antioxidant, an ultraviolet absorber, an antistatic agent, a flame retardant may be added to the center layer 4 and the surface layers 5 and 5 as necessary. And various additives such as a coloring agent.

The center layer 4 and the surface layers 5 and 5 may be composed of a plurality of layers. In addition, another resin layer may be provided between the center layer 4 and the surface layers 5 and 5 as long as the rigidity and the like are not impaired. May be provided.

The base film 2 can be manufactured by a conventional method used for manufacturing a laminated film, for example, a coextrusion method. For example, the base film 2 shown in FIG. 1 includes a resin composition containing the resin forming the center layer 4 and a resin composition containing the resin forming the surface layers 5 and 5 provided with a T die, Can be obtained by melt-extrusion using a two-type three-layer extruder of a feed block type, cooling by a cooling roll, and then performing a stretching treatment (uniaxial stretching or biaxial stretching). Note that an annular die can be used instead of the T die. In the present invention, since both the center layer 4 and the surface layers 5 and 5 are formed of an olefin-based polymer, they can be laminated without using an adhesive. A mold extruder may be used.

The stretching can be performed by any of a tenter method and a tube method. The stretching process is usually performed at 70
At a temperature of about 110 ° C, in the width direction (lateral direction; TD direction)
The stretching is performed by 2.0 to 8.0 times, preferably 3.0 to 7.0 times. In addition, if necessary, the stretching treatment can be performed at a low stretching ratio (for example, about 1.5 times or less) also in the length direction (longitudinal direction; MD direction).
The base film in the present invention thus includes a uniaxially oriented film stretched in only one direction, and a biaxially oriented film stretched mainly in one direction and slightly stretched in a direction perpendicular to the direction. It is. The base film 2 obtained in this manner is in the width direction (mainly the direction in which the stretching process is performed).
Has an orientation and shows heat shrinkage in the direction.

The base film 2 is placed in warm water of 80 ° C. for 10 minutes.
The heat shrinkage in the direction X (for example, the width direction) corresponding to the circumferential direction of the container when immersed for 2 seconds is, for example, 20 to 40.
%, Preferably about 25 to 40%. The heat shrinkage is obtained by the following equation. Heat shrinkage (%) = [｛(original length in direction X) − (direction X
浸漬 / (original length in direction X)] × 100 The heat shrinkage ratio is determined by the type of the resin constituting the central layer 4 and the surface layers 5 and 5 and the stretching conditions such as the stretching ratio. Can be adjusted by appropriately selecting.

The polyolefin-based shrink label 1 of the present invention can be formed on at least one surface of the base film 2 obtained as described above by a desired printing method such as a gravure printing method or a flexographic printing method. To form a printing layer 3.

In the present invention, an aqueous ink is used as a printing ink when forming the printing layer 3. The resin used as the binder of the aqueous ink may be any of a water-soluble resin (solution type), a water-soluble resin [hydrosol type (colloidal dispersion type)] and a water-dispersible resin (emulsion type). Acrylic resin, polyacrylamide resin, polyethylene oxide resin, poly N-vinylpyrrolidone resin, polyurethane resin,
Polyester resin, polyamide resin, amino resin,
Phenolic resins, polyvinyl acetate resins, cellulose resins, synthetic rubbers and other synthetic resins; polynucleotides, polypeptides, polysaccharides, natural polymers such as natural rubber, and the like can be used. These resins can be used alone or in combination of two or more.

Of the above binder resins, a water-soluble resin or a water-dispersible resin is often used, and among the water-soluble resins, an alkali-soluble resin is preferable. This alkali-soluble resin has a carboxyl group in the molecule and is insoluble in water as it is, but is a water-solubilizing agent such as ammonia, an organic amine (eg, diethylamine, triethylamine, ethylenediamine, etc.), an amino alcohol (eg, Addition of alkaline substances such as dimethylaminoethanol) and alkali metal hydroxides (such as sodium hydroxide and potassium hydroxide) can lead to ammonium salts,
It becomes a salt such as an organic amine salt and solubilized to give a colloid solution. In the case where a volatile component such as ammonia is used as the alkaline substance, after printing using an aqueous ink composed of the colloidal solution, when dried, ammonium salts and the like are decomposed to return to the original water-insoluble resin. ,
A film with high water resistance is formed.

Examples of the alkali-soluble resin include one or more unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, and itaconic acid, and an alkyl acrylate ( For example, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and the like, alkyl methacrylate (for example, methyl methacrylate, ethyl methacrylate,
Propyl methacrylate, butyl methacrylate, etc.), hydroxyl group-containing polymerizable unsaturated compound (e.g., hydroxyethyl acrylate, hydroxyethyl methacrylate, etc.), cyano group-containing polymerizable unsaturated compound (e.g., acrylonitrile, methacrylonitrile, etc.), Amide group-containing polymerizable unsaturated compounds (for example, acrylamide, methacrylamide, N-alkoxyacrylamide, N-alkoxymethacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, etc.), styrene compounds (for example, styrene, vinyltoluene) , Α-methylstyrene, divinylbenzene, etc.), olefins (eg, ethylene), allyl group-containing compounds (eg, diallyl phthalate, allyl glycidyl ether, triallyl) Such as isocyanurate),
Examples include vinyl esters (for example, vinyl acetate) and copolymers with a compound having a polymerizable unsaturated group such as N-vinylpyrrolidone. Among these, (meta)
Alkali-soluble acrylic resins containing acrylic acid or methacrylic acid as an unsaturated carboxylic acid component, such as acrylic acid- (meth) acrylic acid alkyl ester copolymer and ethylene- (meth) acrylic acid copolymer, are preferred.

As another preferable resin for an aqueous ink, an aqueous polyurethane resin can be mentioned. Representative examples of the aqueous polyurethane resin include, for example, a compound having an ionic functional group such as a carboxyl group and at least two groups reactive with an isocyanate group, an organic polyisocyanate, and And a polyisocyanate-containing prepolymer obtained by reacting a polyol compound with an organic polyisocyanate in excess of the above conditions, a chain extender, and if necessary, a polyurethane resin obtained by reacting a polymerization terminator. Is done.

Examples of the compound having the ionic functional group and at least two groups reactive with an isocyanate group include 3,5-dihydroxybenzoic acid,
Carboxyls such as 2,2-bis (hydroxymethyl) propionic acid, bis (hydroxymethyl) acetic acid, bis (4-hydroxyphenyl) acetic acid, tartaric acid, N, N-bis (2-hydroxyethyl) -3-carboxypropionamide And a polyol compound having a group.

Examples of the polyol compound used as required include low molecular weight glycols such as ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol and cyclohexanedimethanol. Low molecular weight polyols such as trimethylolpropane, glycerin and pentaerythritol; high molecular weight diols such as polyether diols, polyester diols, polycarbonate polyols, and silicone polyols; bisphenols such as bisphenol A and bisphenol F; Is mentioned.

Examples of the organic polyisocyanate include aromatic diisocyanates such as tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, and 1,5-naphthalene diisocyanate; aliphatic diisocyanates such as hexamethylene diisocyanate; isophorone diisocyanate And alicyclic diisocyanates such as hydrogenated 4,4'-diphenylmethane diisocyanate.

The chain extender includes compounds having two or more active hydrogens capable of reacting with isocyanate groups, for example, diamine compounds, dihydrazide compounds, glycols and the like. Examples of the polymerization terminator include dialkylamines, amino alcohols, and monoamine-type amino acids.

As described above, these polyurethane resins neutralize carboxyl groups in the molecule and are often used as aqueous solutions or aqueous dispersions. For the neutralization, the above-mentioned water-soluble agent can be used.

The water-based ink comprises the above-mentioned water-based ink resin (for example, an alkali-soluble acrylic resin) and water as main components of a vehicle, and a pigment such as a pigment, and, if necessary, a wax and a dispersant. , A defoaming agent, a lubricant, a lubricant, and other additives, and kneading with a mixer or the like. Note that the term “aqueous ink resin and water as the main components of the vehicle” means not only the case where the vehicle is composed of only the aqueous ink resin and water as a solvent, but also, for example, water and a water-miscible organic solvent as a solvent. The meaning includes a case where a mixed solvent with a solvent (for example, an alcohol or the like) is used.

As the water-miscible organic solvent, for example,
Methanol, ethanol, isopropyl alcohol, n
Alcohols such as -butyl alcohol.
Preferred aqueous ink solvents include water-ethanol, water-
A mixed solvent of water and alcohol such as isopropyl alcohol and water-ethanol-isopropyl alcohol is included. When a mixed solvent of water and alcohol is used as the solvent, the ratio between the two can be appropriately selected within a range that does not impair the solubility and dispersibility of the resin. For example, the ratio at the time of printing is water / alcohol (weight ratio) = 50. / 50-98 / 2
Degree, preferably about 65/35 to 95/5. The vehicle may contain a small amount (eg, less than 2% by weight) of a ketone or ester organic solvent.

The pH of the aqueous ink varies depending on the type of resin and the like. For example, when an alkali-soluble acrylic resin is used, the pH is about 7.5 to 9.0 when printing.
It is preferably about 7.8 to 8.2.

The content of the binder resin in the aqueous ink can be appropriately selected within a range that does not impair the printability and the like, and varies depending on the kind of the resin and the like.
About 30% by weight, preferably about 10 to 20% by weight.

The shrink label 1 obtained by forming the printing layer 3 on the surface of the base film 2 in this manner is usually cut into a long strip shape having a desired width, and the printing surface is turned inside. After rounding in a cylindrical shape so that the direction X is the circumferential direction, and bonding both ends by an organic solvent or heat fusion, etc.,
It is cut into a desired length as needed and used as a cylindrical shrink label. The shrink label thus formed in a tubular shape can be easily mounted on a container having a tubular body. In addition, since the surface layers 5 and 5 can be welded with an organic solvent, the bonding with the organic solvent is more preferable than the thermal fusion in which the contraction property of the bonding portion is deteriorated. In addition, the shrink label center-sealed with the organic solvent does not have wrinkles at the joints and exhibits an excellent appearance.

Examples of the organic solvent include hydrocarbons such as hexane, cyclohexane and toluene; halogenated hydrocarbons such as methylene chloride; diethyl ether;
One or several mixtures of linear or cyclic ethers such as ethylene glycol dimethyl ether and tetrahydrofuran; ketones such as acetone, methyl ethyl ketone and cyclohexanone; and esters such as ethyl acetate and butyl acetate. Among them, the boiling point is 20 to 70
An organic solvent of about ° C is preferred in terms of workability and the like.

The object 6 to which the shrink label 1 of the present invention is attached includes, for example, containers such as plastic containers and glass containers. Examples of the resin constituting the plastic container include vinyl polymers such as olefin polymers such as polypropylene and styrene polymers such as polystyrene, polyester, and vinyl chloride resin. The resin may be a foamed resin (for example, a styrene foam resin).

When the object 6 is made of a propylene-based polymer such as polypropylene, the main component of the shrink label 1 is a propylene-based polymer. In this case, there is a great merit that a complicated step of separating the mounted object 6 and the label 1 can be omitted.

The shrink label 1 is placed in a container (object to be mounted) 6.
As a method of attaching the device to the device, a known or commonly used method can be applied. For example, the shrink label 1 formed in a cylindrical shape is supplied to an automatic label mounting device, and cut into a required length.
The shrink label 1 can be attached to the container 6 by fitting the container into a container 6 filled with ordinary contents and heating the container with hot air at a predetermined temperature (for example, about 80 to 200 ° C.) or radiant heat such as infrared rays.

In the present invention, the base film 2 constituting the shrink label 1 has a multilayer structure in which surface layers 5 and 5 made of an amorphous cyclic olefin polymer are laminated on both sides of a central layer 4 made of a propylene polymer. As a result, compared to the case where a conventional base film is formed of a propylene-based polymer, the base film has excellent gloss and good transparency, so that printing is beautiful. In addition, curling during printing can be prevented, and the amount of organic solvent remaining on the label after printing can be significantly reduced, so that blocking and organic solvent odor caused by the remaining solvent can be prevented. Furthermore, since it can be easily sealed with an organic solvent as described above, wrinkles and the like hardly occur, and the appearance is good. In addition, since the rigidity is high, the production line speed can be increased, the productivity can be improved, and the cost can be reduced because the thickness can be reduced. Furthermore, upon heat shrinkage, the shrinkage speed is high, and after the heat source is separated, it does not loosen even after a long time, so that it has excellent fit (adhesion, tightening) to an object to be mounted.

[0048]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 Ethylene-propylene random copolymer (trade name "Grand Polypro", ethylene content 4.5% by weight, Co., Ltd.)
A mixture (a1) of 100 parts by weight of Grand Polymer) and 25 parts by weight of hydrogenated petroleum resin (trade name “Alcon”, manufactured by Arakawa Chemical Co., Ltd.) and an amorphous cyclic olefin polymer (trade name “Apel APL6509”) ”, Density 1.02 g / cm
^3, Mitsui Chemicals Co., Ltd.) (b1) and a merging scheme the width direction (TD direction in coextrusion, then 100 ° C. from a T-die using a two-kind three-layer extruder of a feed block method)
(B1) / (a
1) / (b1) 30 μm thick (central layer (a
1) thickness: 22 μm, surface layer (b1) thickness: 4 μ each
m) was obtained. A test piece of 10 cm × 10 cm (length in the width direction (TD direction) × length in the length direction (MD direction)) was cut out from the base film, and the test piece was immersed in warm water at 80 ° C. for 10 seconds. Then, the length in the width direction (TD direction) of the base film was measured, and the heat shrinkage was determined by the above equation to be 30%. On the other hand, an acrylic acid-butyl acrylate-methyl methacrylate copolymer was added to an aqueous ammonia solution and mixed with 50 parts by weight of a varnish (solid content: 30% by weight), 15 parts by weight of a pigment,
An aqueous ink was prepared by kneading 0.001 part by weight of silicone oil, 2 parts by weight of isopropyl alcohol, and 33 parts by weight of water. One surface of the base film obtained above is subjected to a corona discharge treatment to reduce the surface wetting tension to 500 μm.
After setting to N / cm, gravure printing of a design consisting of eight colors was performed using the aqueous ink to form a printing layer, and the layer was wound into a roll. After slitting the obtained printing roll into a predetermined width to form a plurality of rolls, each roll is rewound, the printing layer is turned inside, and the width direction (TD direction) of the base film is the circumferential direction. The resulting product was rolled into a tubular shape, and both ends were adhered with an organic solvent (tetrahydrofuran) to obtain a continuous tubular shrink label. The continuous shrink label body is supplied to an automatic label mounting apparatus, cut into each label, and then externally fitted into an inverted frustoconical polypropylene vertical cup noodle container (with an internal volume of about 400 ml), and heated with a hot-air heating tunnel (temperature: (80-150 ° C.) and heat shrinked to attach the label to the container. as a result,
Both the mounting property and the finish of the label were good. Further, there was no problem such as curling at the time of printing and blocking due to the residual solvent.

[0050]

According to the shrink label of the present invention, since the base film has a multilayer structure composed of a specific polymer and the printing layer is formed of an aqueous ink, strength, gloss, natural shrinkage, heat resistance, With excellent fit to the adherend during shrinkage, solvent sealing is possible, and blocking due to curl and residual solvent during printing,
Generation of organic solvent odor can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a polyolefin-based shrink label of the present invention.

FIG. 2 is a perspective view showing a state when the shrink label of FIG. 1 is mounted on an object.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Polyolefin shrink label 2 Base film 3 Printing layer 4 Center layer 5 Surface layer 6 Attached object

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09F 3/02 G09F 3/02 F // C08L 23:10 C08L 23:10 F term (Reference) 4F071 AA14 AA20 AF61 AH04 AH06 BA01 BB06 BB08 BC01 BC17 4F100 AK02 AK02B AK02C AK07A AK25 AK25J AK64 AL01 AL03 BA04 BA07 BA10C BA10D BA13 EH20 EJ37 EJ38 EJ55 GB90 HB31D JA03 JA12B JA12C JK01 JN21 Y

Claims (4)

[Claims] 1. A shrink label having a printing layer provided on at least one surface of a base film, wherein the base film has a central layer made of a propylene-based polymer, and a non-laminate laminated on both surfaces of the central layer. A polyolefin-based shrink label comprising a monoaxial or biaxially oriented polyolefin-based film composed of a surface layer composed of a crystalline cyclic olefin-based polymer, and wherein the printing layer is formed of an aqueous ink. 2. The polyolefin-based shrink label according to claim 1, comprising a base film having a heat shrinkage in the main orientation direction X of 20% or more when immersed in warm water at 80 ° C. for 10 seconds. 3. The polyolefin shrink label according to claim 1, wherein the printing layer is formed of an aqueous ink containing an alkali-soluble acrylic resin and water as main components of the vehicle. 4. The polyolefin-based shrink label according to claim 1, wherein the polyolefin-based shrink label is formed in a cylindrical shape such that the main orientation direction X is the circumferential direction.