JP2006116874A - Polyolefinic shrinkable label - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an olefin-based shrinkable label which excels in stiffness, gloss, natural shrink and fitness to an adherend at the time of heat shrink, has high interlayer adhesive strength and in addition is economical. <P>SOLUTION: The polyolefinic shrinkable label 1 is the one in which a print layer 3 is provided on at least one surface of a base film 2. The base film 2 is composed of a central layer 4 consisting of a propylene polymer and surface layers 5, 5 which are provided on both the surfaces of the central layer and which contains 1-40 pts.wt. of a propylene polymer and 0-20 pts.wt. of polyethylene to 100 pts.wt. of an amorphous cycloolefin-based polymer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a shrink label that is attached to a container such as a plastic container or a glass container by heat shrinkage.

  Conventionally, as a shrink label (heat-shrinkable label) to be attached to a container such as a polyethylene terephthalate bottle (PET bottle), one using a base film made of a polyvinyl chloride polymer has been used. However, since the label with the base film formed of a polyvinyl chloride polymer has a problem of generating toxic gas and dioxin at the time of incineration after disposal, the use of a polyolefin-based shrink label has been studied in recent years ( Patent Literatures 1 to 3).

  As such a polyolefin-based shrink label, for example, a label having a non-halogen-based stretched polypropylene (OPP) film as a base film is used. However, conventional shrink labels made of heat-shrinkable OPP film have advantages such as low specific gravity and relatively low cost, but they are not always satisfactory in terms of waist strength and gloss, and natural There were problems such as large shrinkage, poor fit at the time of heat shrinkage, and inability to perform solvent sealing.

  As a result of studying methods for solving these problems, the present inventors have found that a base film of a shrink label is formed of a center layer made of a propylene-based polymer and an amorphous cyclic olefin-based polymer laminated on both sides of the center layer. It has been found that when composed of a combined surface layer, the strength of the waist, gloss, natural shrinkage, fit during heat shrinkage are improved, and sealing with a solvent is possible. However, such a label has a problem in that the center seal strength is not sufficient because the interlayer adhesion strength (adhesion) between the surface layer and the center layer is low.

  In JP 2004-170468 A, a base film is composed of a propylene polymer, an amorphous cyclic olefin polymer and a central layer made of polyethylene, and an amorphous cyclic olefin system laminated on both sides of the central layer. A shrink label composed of a polymer and a surface layer made of polyethylene is disclosed. According to this label, the interlayer adhesive strength can be improved, but it is economically disadvantageous because it is necessary to add an expensive amorphous cyclic olefin polymer to both the surface layer and the center layer. In addition, since this label is inferior in compatibility between polyethylene, which is a constituent component of the surface layer, and the amorphous cyclic olefin, the thickness accuracy at the time of film formation is low. There is a problem that the thickness of the label is large, and the transparency of the base film is low, so that the appearance of the entire label is poor.

Japanese Patent Laid-Open No. 2002-215044 JP 2002-234115 A JP 2000-159946 A JP 2004-170468 A

An object of the present invention is to provide an economical olefin-based shrink label that is excellent in waist strength, gloss, natural shrinkage, fit to an adherend during heat shrinkage, and has high interlayer adhesion strength. There is.
Another object of the present invention is to provide an olefin-based shrink label having an excellent appearance and improved thickness accuracy in addition to the above characteristics.

  As a result of intensive studies to achieve the above object, the inventors of the present invention have not only excellent gloss and fitting properties, but also interlayer adhesion strength when the base film is composed of a surface layer and a center layer made of specific components. As a result, it was found that a polyolefin-based shrink label excellent in thickness accuracy and appearance characteristics can be obtained at low cost, and the present invention has been completed.

  That is, the present invention is a shrink label in which a printed layer is provided on at least one surface of a base film, and the base film is provided on a central layer made of a propylene-based polymer and on both sides of the central layer. A polyolefin-based shrink label comprising 1 to 40 parts by weight of a propylene polymer and 0 to 20 parts by weight of polyethylene for 100 parts by weight of an amorphous cyclic olefin polymer. I will provide a.

  In the polyolefin-based shrink label of the present invention, the amorphous cyclic olefin polymer is preferably a cyclic olefin ring-opening polymer or a hydrogenated product thereof. The propylene-based polymer in the surface layer and / or the center layer is preferably a propylene-based random copolymer obtained by copolymerization using a metallocene catalyst. The surface layer may further contain a petroleum resin.

  According to the polyolefin-based shrink label of the present invention, since the base film is composed of a surface layer and a center layer composed of specific components, the strength and gloss of the waist, natural shrinkage, to the adherend during heat shrinkage In addition to excellent fit, interlayer adhesion strength is improved, thickness accuracy and appearance characteristics are excellent, and cost can be reduced.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic sectional view showing an example of a polyolefin-based shrink label of the present invention. A polyolefin-based shrink label 1 in FIG. 1 includes a base film 2 and a printed layer 3 provided on one surface of the base film 2. The base film 2 includes a central layer 4 made of a propylene polymer, and surface layers 5 and 5 made of an amorphous cyclic olefin polymer, a propylene polymer, and polyethylene laminated on both sides of the central layer 4. And a polyolefin-based film composed of

  As the propylene polymer constituting the center layer 4 of the base film, various polymers containing propylene as a constituent monomer can be used. As a preferable propylene-based polymer, a propylene-based random polymer obtained by copolymerization using a metallocene catalyst is preferable in that it can improve low-temperature shrinkage of about 60 to 80 ° C. and fitability to a container during heat shrinkage. A copolymer is mentioned. A propylene random copolymer can be prepared by copolymerizing propylene and a copolymerizable monomer using a metallocene catalyst. Examples of the copolymerizable monomer include propylene such as ethylene, butene-1, pentene-1, hexene-1, 4-methyl-1-pentene, octene-1, and the like, such as α-olefin having 2 or 4 to 20 carbon atoms. Other α-olefins are preferably used. Ethylene is optimal as the copolymerizable monomer component. The copolymerizable monomer components can be used alone or in admixture of two or more.

  As the metallocene catalyst, a known or commonly used metallocene catalyst for olefin polymerization can be used, and specifically, a metallocene catalyst described in JP-A No. 2002-215044 can be used. The copolymerization method is not particularly limited, and a known polymerization method such as a slurry method, a solution polymerization method, or a gas phase method can be employed. The propylene-based random copolymer preferably has an isotactic index of 90% or more from the viewpoint of low-temperature shrinkage and film stiffness.

  A typical example of the propylene random copolymer is an ethylene-propylene random copolymer. The ethylene content in the ethylene-propylene random copolymer is, for example, 2 to 5% by weight, preferably about 3 to 4.5% by weight.

  As the ethylene-propylene random copolymer, those having a melting point of 115 to 140 ° C. can be used. As the ethylene-propylene random copolymer, those having a melting point of 130 ° C. or lower (for example, 120 to 130 ° C., preferably 120 to 125 ° C.) are optimal for improving the low temperature shrinkability. Moreover, what is excellent in heat resistance is obtained as melting | fusing point is 120 degreeC or more (for example, 120-140 degreeC, Preferably 125-140 degreeC).

  Another typical example of the propylene random copolymer is a terpolymer of ethylene, propylene, and butene. These propylene polymers can be used alone or in combination of two or more.

  The center layer 4 may further contain a small amount of another polymer as necessary. Further, as will be described later, after stretching the base film, it is possible to recycle fragments generated by cutting off the film end for improving the thickness accuracy. For example, when the film fragment is added in an amount of 1 to 40% by weight, preferably 10 to 30% by weight, based on the entire center layer 4, the interlayer adhesive strength between the center layer 4 and the surface layers 5 and 5 is improved. A label having excellent transparency and excellent appearance can be obtained.

  The thickness of the center layer 4 is, for example, about 10 to 70 μm, preferably about 20 to 50 μm.

  The surface layers 5 and 5 include an amorphous cyclic olefin polymer, a propylene polymer, and polyethylene. Polyethylene is not an essential component of the surface layers 5 and 5, and the surface layers 5 and 5 can be composed of at least an amorphous cyclic olefin polymer and a propylene polymer.

  The amorphous cyclic olefin polymer includes (A) a copolymer of an α-olefin such as ethylene, propylene, 1-butene, 1-hexene, 4-methyl-1-pentene and at least one cyclic olefin. (Hereinafter, sometimes referred to as “cyclic olefin copolymer”) and (B) a ring-opened polymer of cyclic olefin or a hydrogenated product thereof.

Examples of the cyclic olefin in the polymers (A) and (B) include bicyclo [2.2.1] hept-2-ene (norbornene), tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, hexacyclo [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, heptacyclo-5-icosene, heptacyclo-5-henicosenoic, tricyclo [4.3.0.1 ^{2, 5]-3-decene,} tricyclo [4.3.0.1 ^{2 , 5} ] -3-undecene, pentacyclo [6.5.1.1 ^3,6 . 0 ^2,7 . 0 ^9,14 ] -4-pentadecene, pentacyclopentadecadiene, pentacyclo [4.7.0.1 ^2,5 . 0 ^8,13 . 1 ^9,12] -3-pentadecene, Nonashikuro [9.10.1.1 ^{4, 7.} 1 ^13,20 . 1 ^15,18 . 0 ^2,10 . 0 ^12,21 . 0 ^14,19] -5-pentacosene include polycyclic olefins such like. These cyclic olefins may have substituents such as ester groups such as methoxycarbonyl and ethoxycarbonyl groups, alkyl groups such as methyl groups, haloalkyl groups, cyano groups, and halogen atoms in the ring.

  The cyclic olefin copolymer (A) is, for example, a so-called Ziegler catalyst or metallocene catalyst obtained by combining the α-olefin and the cyclic olefin in a hydrocarbon solvent such as hexane, heptane, octane, cyclohexane, benzene, toluene, and xylene. It can obtain by superposing | polymerizing using catalysts, such as. Such a cyclic olefin copolymer (A) is commercially available, and for example, trade name “Apel” (manufactured by Mitsui Chemicals), trade name “TOPAS” (manufactured by Ticona) and the like can be used.

  The ring-opening polymer of the cyclic olefin or the hydrogenated product (B) thereof is usually obtained by subjecting the cyclic olefin to metathesis polymerization (ring-opening polymerization) using a molybdenum compound or a tungsten compound as a catalyst, for example. It can be produced by further hydrogenation of the polymer. Such a polymer (B) is commercially available. For example, the trade name “ARTON” (manufactured by JSR Corporation), the trade name “ZEONEX” (manufactured by Nippon Zeon Co., Ltd.), the trade name “ZEONOR” (Japan) Zeon Co., Ltd.) can be used. These amorphous cyclic olefin polymers can be used alone or in combination of two or more.

  The amorphous cyclic olefin-based polymer is appropriately selected and used depending on the compatibility with the other components constituting the surface layers 5 and 5. In the present invention, a cyclic olefin ring-opening polymer or a hydrogenated product thereof (B) is used in that the compatibility with the polypropylene polymer constituting the surface layers 5 and 5 is good and the film-forming property can be improved. Is preferably used.

  The glass transition temperature (Tg) of the amorphous cyclic olefin polymer is, for example, about 50 to 80 ° C., preferably about 60 to 80 ° C., and particularly preferably 65 to 75 ° C. in terms of improving the low temperature shrinkability. It is. The glass transition temperature of the amorphous cyclic olefin polymer can be adjusted by the type and blending ratio of monomer components such as cyclic olefin.

  As the propylene-based polymer in the surface layers 5 and 5, the same propylene-based polymer as the above-described center layer 4 can be used. In the present invention, by including a propylene-based polymer in the center layer 4 and the surface layers 5 and 5, the interlayer adhesive strength between the center layer 4 and the surface layers 5 and 5 can be increased, and the center seal strength can be improved. . In addition, the kind of propylene polymer which comprises the center layer 4 and the surface layers 5 and 5 may be the same, and may differ. The amount of the propylene polymer used is 1 to 40 parts by weight, preferably 10 to 30 parts by weight, based on 100 parts by weight of the amorphous cyclic olefin polymer. If the amount used is less than 1 part by weight, the effect of improving the interlayer adhesive strength cannot be obtained, and if it exceeds 40 parts by weight, the compatibility with the amorphous cyclic olefin is deteriorated and the appearance characteristics such as haze are affected. Will be affected.

  The polyethylene in the surface layers 5 and 5 is not particularly limited, and is known or commonly used polyethylene [for example, low density polyethylene (LDPE), linear low density polyethylene (LLDPE), very low density polyethylene, medium density polyethylene, high density polyethylene, Density polyethylene (HDPE) and the like] can be used. As the polyethylene, low-density polyethylene (including linear low-density polyethylene and ultra-low-density polyethylene) having a density of less than 0.930 (g / cm 3) is preferable, and linear low-density polyethylene is most preferable.

The low-density polyethylene (including linear low-density polyethylene and ultra-low-density polyethylene) preferably has a density of 0.880 (g / cm ³ ) or more and less than 0.930 (g / cm ³ ). In particular, those of 0.910 (g / cm ³ ) or more and 0.929 (g / cm ³ ) or less are preferable. The density of polyethylene can be measured according to JIS K7112.

  The amount of polyethylene used is, for example, about 0 to 20 parts by weight with respect to 100 parts by weight of the amorphous cyclic olefin polymer. If the amount used exceeds 20 parts by weight, the polyolefin-based shrink label becomes too soft, which is not preferable. In addition, when the surface layers 5 and 5 do not contain polyethylene as a constituent component, the compatibility with the amorphous cyclic olefin polymer and the propylene polymer which are other components is high, and the transparency is excellent. Thickness accuracy can be improved. On the other hand, when the surface layers 5 and 5 contain polyethylene, oil resistance can be imparted to the label surface, and whitening due to adhesion of oils and fats can be prevented and gloss can be maintained.

  The surface layers 5 and 5 may further contain other polymers as necessary. The thickness of each of the surface layers 5 and 5 is, for example, about 3 to 15 μm, preferably about 3 to 10 μm. Moreover, the ratio with respect to the thickness of the base film 2 of the total thickness of both the surface layers 5 and 5 is 3 to 50%, for example, Preferably it is about 5 to 30%. When this ratio is smaller than 3%, it tends to be in a relaxed state (a state in which tightening due to contraction is loosened) after heat contraction. Further, since the amorphous cyclic olefin polymer is relatively expensive, the ratio is preferably 30% or less.

  In order to improve printability, the surface of the surface layer 5 on the printed layer 3 side may be subjected to conventional surface treatment such as corona discharge treatment, plasma treatment, flame treatment, or anchor coating treatment. As the anchor coating agent used for the anchor coating treatment, a known or conventional anchor coating agent can be used. Moreover, when using water-based printing ink, the anchor coating agent containing acrylic copolymer resin and a nitrogen atom containing high molecular compound can also be used as this anchor coating agent.

  The acrylic copolymer resin may be any resin that exhibits adhesion to olefin resins. For example, a single or copolymer of an acrylic monomer such as (meth) acrylic acid or (meth) acrylic acid ester Or a copolymer of the acrylic monomer and other monomers such as a styrene monomer, a carboxyl group-containing monomer, an acid anhydride group-containing monomer, vinyl chloride, an olefin, and vinyl esters.

  Examples of the nitrogen atom-containing polymer compound include (i) a polymer amine compound having an amino group (including a hydrazino group) in the main chain or side chain of the polymer, and (ii) a cationic compound in the side chain of the polymer. Examples thereof include a polymer compound having a quaternary ammonium base, (iii) a polymer amide compound having an amide group in the side chain, and (iv) a polyamide resin having a main chain formed by an amide bond.

  The center layer 4 and the surface layers 5 and 5 may contain tackifiers such as petroleum resins, terpene resins, rosin resins, coumarone / indene resins, styrene resins, and hydrogenated products thereof, as necessary. . In particular, by including petroleum resin, terpene resin, especially hydrogenated petroleum resin, hydrogenated terpene resin, etc. in the central layer 4, transparency, waist strength, heat shrinkability at low temperature, etc. can be improved. It is preferable in that it can be performed. 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. Each can be a commercially available product. Moreover, it is preferable to add a tackifier to the surface layers 5 and 5 rather than the center layer 4 from the point of the improvement of thickness accuracy, for example, petroleum resin is added about 10 to 30 weight% of the whole surface layers 5 and 5. can do.

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

  The center layer 4 and the surface layers 5 and 5 can each be composed of a plurality of layers. Further, another resin layer may be provided as long as the rigidity and the like are not impaired, and an overcoat layer made of an acrylic resin or the like may be provided on the surface of the surface layers 5 and 5 for preventing damage.

  The thickness of the base film 2 is, for example, about 20 to 80 μm (preferably 30 to 60 μm).

  The base film 2 can be produced by a conventional method used when producing a laminated film, such as a coextrusion method. For example, the base film 2 shown in FIG. 1 includes a resin composition containing a resin that forms the center layer 4 and a resin composition containing a resin that forms the surface layers 5 and 5. Can be obtained by melt-extrusion using a two-type three-layer type extruder having a feed block method, cooling with a cooling roll, and then stretching. An annular die can be used instead of the T die. Further, the resin composition according to the center layer 4 is melt-extruded to produce a single-layer film, and the resin layers of the surface layers 5 and 5 are laminated thereon by a laminating method, and then subjected to a stretching treatment to form a base film. 2 can also be obtained.

  Stretching can be performed by either a tenter method or a tube method. The stretching treatment is usually carried out by stretching at a temperature of about 80 to 180 ° C. (preferably 80 to 150 ° C.) in the width direction (lateral direction; TD direction) 4 to 8 times, preferably about 5 to 7 times. Is called. In addition, if necessary, a stretching process can be performed in the length direction (longitudinal direction; MD direction) at a low stretching ratio (for example, about 1.5 times or less). Thus, the base film in the present invention includes a uniaxially oriented film stretched only in one direction, and a biaxially oriented film mainly stretched in one direction and slightly stretched in a direction perpendicular to the direction. It is. The base film 2 thus obtained has orientation in the width direction (mainly the direction subjected to the stretching treatment) and exhibits heat shrinkability in the direction.

  The thermal contraction rate in the main orientation direction X (mainly the direction in which the stretching treatment is performed; the width direction in the above case) after the base film 2 is immersed in warm water of 90 ° C. for 10 seconds is, for example, preferably 30 to 80%. Is about 40-70%. In the present invention, since such physical properties can be imparted to the base film, thermal shrinkage is possible at a low temperature and a low heat quantity. For this reason, for example, it can be easily attached to a container having a curved surface with good adhesion.

Further, the thermal contraction rate in the direction X (for example, the width direction) corresponding to the circumferential direction of the container when the base film 2 is immersed in warm water of 80 ° C. for 10 seconds is, for example, about 20 to 40%, preferably It is about 25 to 40%. In addition, the said heat shrinkage rate is calculated | required by a following formula.
Thermal contraction rate (%) = [{(original length in direction X) − (length after immersion in direction X)} / (original length in direction X)] × 100
The thermal contraction rate can be adjusted by appropriately selecting the type of resin constituting the center layer 4 and the surface layers 5 and 5, stretching conditions such as the stretching ratio, and the like.

  When the stretching process is performed by a tenter method, a step of cutting the end of the film is provided, and the cut portion (fragment) is recycled as necessary. By the cutting step, the difference in thickness between the film end after stretching and the center can be corrected, and a base film with improved thickness accuracy can be obtained. Further, by adding the film fragment to the center layer 4, the cost can be reduced, and the interlayer adhesive strength between the center layer 4 and the surface layers 5 and 5 can be improved, and a label having sufficient center seal strength can be obtained. it can.

  The polyolefin-based shrink label 1 of the present invention can be produced by printing a desired image and characters on at least one surface of the base film 2 by a conventional printing method such as gravure printing to form a printed layer 3. .

  The shrink label 1 thus obtained is processed into a desired shape and used according to the purpose. For example, with the printed layer 3 of the shrink label 1 on the inner surface side, the base film 2 is rolled into a cylindrical shape so that the main stretching direction (usually the width direction) is the circumferential direction, and both ends are overlapped in an envelope-attached shape. Further, it is possible to form a continuous cylindrical shrink label by bonding (center seal) with a solvent, heat fusion or the like, and cut into individual labels to form a cylindrical shrink label. Note that an overcoat layer made of an acrylic resin or the like can be provided on the surface (the outer surface side) of the base film 2 in order to prevent damage.

  In the labeled container of the present invention, for example, the shrink label 1 is mounted on the container 6 as shown in FIG. The material of the container 6 is not particularly limited, and may be any of a plastic container made of polyester such as polyethylene terephthalate, a glass container, and a metal container. The shape of the container 6 may be any of a polygon such as a substantially quadrangular cross section and a cylindrical shape having a circular cross section.

  The container with a label of the present invention supplies, for example, the above-described cylindrical shrink label 1 having the printed layer 3 on the inner surface side to an automatic label mounting apparatus, cuts it to a required length, and then normally fills the contents. It can be manufactured by being externally fitted to the container 6 and passing through a hot air tunnel or a steam tunnel at a predetermined temperature, or by heat shrinkage by heating with radiant heat such as infrared rays. Thus, the shrink label 1 fits closely to the shape of the shoulder portion of the container 6 and the like.

  In addition, since the olefin type shrink label of the present invention uses a polyolefin resin, it has a specific gravity different from that of polyester (polyethylene terephthalate). Separation of the polyolefin resin as the component from the polyethylene terephthalate of the bottle becomes easy.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Example 1
Amorphous cyclic olefin polymer [trade name “ZEONOR 750R”, manufactured by Nippon Zeon Co., Ltd .; Tg 70 ° C., density 1.01, ring-opened polymer of cyclic olefin] 65 parts by weight, obtained using a metallocene catalyst 15 parts by weight of ethylene-propylene random copolymer (trade name “Wintech 1987F”, manufactured by Nippon Polychem) and linear low density polyethylene (trade name “Kernel KF380”, manufactured by Nippon Polyethylene Co., Ltd .; density 0 .918 g / cm ³ ) and a hydrogenated petroleum resin (trade name “Arcon P120”, manufactured by Arakawa Chemical Co., Ltd.), a master batch (trade name “KAMB1”, Nippon Zeon (trade name) A surface layer resin composition comprising 20 parts by weight, and an ethylene-propylene random copolymer obtained using a metallocene catalyst (same as above: central layer) (B1) by co-extrusion from a T die using a two-type three-layer type extruder whose merging method is a feed block method, and then stretching ten times in the width direction (TD direction) at 100 ° C. A base film having a layer structure of / (a1) / (b1) and a thickness of 50 μm (the thickness of the central layer (a1): 40 μm, the thickness of the surface layer (b1): 5 μm each) 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 placed in warm water at 80 ° C. and 90 ° C. After soaking for 2 seconds, the length of the base film in the width direction (TD direction) was measured, and the thermal shrinkage rate was determined by the above formula. The heat shrinkage of this base film was 27% at 80 ° C. and 42% at 90 ° C.
One surface of the base film was subjected to gravure printing with a design of 8 colors using a reactive urethane-based ink to form a printed layer to obtain a shrink label.

  The obtained shrink label is wound into a roll shape, slit into a predetermined width to form a plurality of roll-shaped products, each roll-shaped product is rewound, and the width direction (TD direction) of the base film is the circumferential direction. Thus, the printed layer was turned inside and rolled into a cylindrical shape, and both ends were bonded (center seal) with an organic solvent (cyclohexane) to obtain a continuous cylindrical shrink label. This shrink label continuum is supplied to an automatic label mounting device, cut into each label, and then externally fitted into a 500 ml PET bottle container (polyethylene terephthalate container) and passed through a steam tunnel (temperature: 80 ° C.) for heat. By shrinking, the labeled container shown in FIG. 2 was produced. The adhesiveness of the label to the container was high and the tightening property was excellent.

Comparative Example 1
In Example 1, 15 parts by weight of linear low density polyethylene (trade name “Kernel KF380”, manufactured by Nippon Polyethylene Co., Ltd .; density 0.918 g / cm ³ ) was used in place of the ethylene-propylene random copolymer. A base film was obtained by performing the same operation as in Example 1 except for the above point. The heat shrinkage of this base film was 30% at 80 ° C. and 43% at 90 ° C.
By using this base film, a shrink label and a labeled container were obtained by the same operation as in Example 1.

(Evaluation test)
Interlaminar adhesive strength One side edge of each base film obtained in the examples and comparative examples was coated with a solvent (cyclohexane) with a width of 3 mm and overlapped with the other side edge to center seal, the center seal part Was cut in a circumferential direction with a width of 15 mm, the unbonded portion of this end portion was pulled with a tensile tester (based on JIS K 7127), and the tensile strength (peeling strength with a width of 15 mm) was measured. In the above tensile test, peeling occurred between the surface layer and the central layer constituting the film before the one film adhered with the solvent was peeled from the other film at the center seal portion. The tensile strength at the time of occurrence was measured and defined as interlayer adhesion strength. The tensile strength is 1.2 N for the base film of Example 1 and 0.7 N for the base film of Comparative Example 1, and the interlayer adhesion strength of the base film of Example 1 is improved as compared to Comparative Example 1. It was.

Thickness accuracy About the width direction (TD direction) where the stretching process of each base film obtained in the examples and comparative examples was performed, the thicknesses at both ends and the central portion were measured and evaluated as thickness accuracy. The difference between the maximum value and the minimum value of the obtained thickness is 2.0 μm for the base film of Example 1 and 5.0 μm for the base film of Comparative Example 1, and the base film of Example 1 has excellent thickness accuracy. It was.

Appearance characteristics About the appearance characteristics of the base films obtained in the examples and comparative examples, a haze meter (trade name “DIRECT READING HAZEMETER” manufactured by Toyo Seiki Seisakusho Co., Ltd.) was used, and the degree of haze was measured according to JIS K-7105. ) It was evaluated by measuring [%]. The obtained haze is 5.9% for the base film of Example 1 and 8.2% for the base film of Comparative Example 1. The base film of Example 1 is highly transparent and exhibits an excellent appearance. It was.

It is a schematic sectional drawing which shows an example of the polyolefin-type shrink label of this invention. It is a schematic sectional drawing which shows an example of the labeled container of this invention.

Explanation of symbols

1 Shrink Label 2 Base Film 3 Print Layer 4 Center Layer 5 Surface Layer 6 Container

Claims (4)

  A shrink label in which a printed layer is provided on at least one surface of a base film, wherein the base film is a central layer made of a propylene-based polymer, and an amorphous cyclic olefin provided on both sides of the central layer. A polyolefin-based shrink label comprising 1 to 40 parts by weight of a propylene polymer and 0 to 20 parts by weight of a polyethylene based on 100 parts by weight of a polymer.   2. The polyolefin-based shrink label according to claim 1, wherein the amorphous cyclic olefin-based polymer is a cyclic olefin ring-opening polymer or a hydrogenated product thereof.   The polyolefin shrink label according to claim 1 or 2, wherein the propylene polymer in the surface layer and / or the center layer is a propylene random copolymer obtained by copolymerization using a metallocene catalyst.   The polyolefin shrink label according to any one of claims 1 to 3, wherein the surface layer contains a petroleum resin.

Images