JP2005199650A - Heat shrinkable polyolefin-based laminated film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat shrinkable olefinic film which does not cause mutual sticking of bottles with each other even when storing in a warmer for hot drinks, has good quality balance, particularly as a label, is lightweight and can be separated when recycling by a specific gravity separation method in the case of the label having a specific gravity of <1. <P>SOLUTION: In this heat shrinkable olefinic film, the both faces thereof are formed of a resin composition mainly comprising a cyclic olefin-based copolymer resin having a glass transition point of 60-90°C, and an intermediate layer is an oriented film of a resin composition mainly comprising an olefinic resin. Further, at least one surface of the above film has a transparent coating layer containing, as a vehicle, an acrylic resin having the glass transition point of 50-90°C. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a heat-shrinkable olefin-based laminated film that has excellent heat resistance, scratch resistance, and slipperiness, particularly has a good quality balance for labels, and can be easily separated from a PET bottle by a liquid specific gravity separation method.

  In recent years, when selling PET bottles used as containers for beverages, a heat-shrinkable label whose inner surface is printed is attached to the outside of the container in order to differentiate it from other products and improve the visibility of the product. There are many cases. Examples of the label material include polystyrene, polyester, polyvinyl chloride, and polyolefin. PET bottles collected after use are recycled into flakes and pellets. At that time, the crushed material is put in water and floats in water (heat-shrinkable labels and caps with a specific gravity of less than 1) and sinks in water (specific gravity) Is subjected to a process of separating one or more heat-shrinkable labels and PET bottle crushed bodies). Therefore, a heat-shrinkable label having a high specific gravity separation efficiency, that is, a specific gravity of less than 1, has been desired. In addition, since the development of plastic bottles for hot beverages such as tea and coffee in recent years, it has been increasing that products are kept warm in hot beverage warmers at convenience stores and the like. The temperature of the hot beverage warmer is controlled between about 60 to 85 ° C., and the heat-shrinkable label of the PET bottle for hot beverage needs a certain degree of heat resistance. Accordingly, there has been a demand for a heat-shrinkable label for a hot beverage plastic bottle that does not cause the problem that the bottles stick to each other under the above temperature control and the problem that the label crystallizes and becomes cloudy.

  Among the label materials, polystyrene, polyester, and polyvinyl chloride labels have a specific gravity greater than 1, so that there is a problem that separation by the specific gravity separation method is difficult in the recycling process. On the other hand, the polyolefin label has a specific gravity of less than 1, but has a problem that its waist and gloss are insufficient and cannot be produced by center seal processing with an organic solvent.

When these problems were examined, a shrink film having a specific gravity of 1 or less in which a layer made of an amorphous resin such as a cyclic olefin resin and a layer made of a polyolefin resin was laminated was found. The heat-shrinkable film made of this cyclic olefin resin is excellent in transparency and gloss, and has an appropriate waist, so that it has been studied as a variety of packaging materials. For example, in Patent Document 1, a layer composed mainly of an olefin resin having a specific gravity of less than 0.94 g / cm ³ is used as an intermediate layer, and layers having a cyclic polyolefin resin as a main component are provided on the front and back surfaces to form a laminate. A heat-shrinkable film having a specific gravity of less than 0.96 obtained by stretching the laminate 3 to 6 times is disclosed. Moreover, in patent document 2, the lamination | stacking heat | fever which consists of the intermediate | middle layer which mainly consists of the front and back layer which blended 60-150 weight part of linear low density polyethylene with respect to 100 weight part of cyclic olefins, and a propylene-alpha-olefin random copolymer. A shrink film is disclosed. Further, Patent Document 3 discloses an olefinic heat-shrink label having excellent scratch resistance by applying a transparent coating to a base film made of an amorphous olefin polymer.
However, these films have insufficient heat resistance, and there is a problem that bottles tend to stick to each other in a hot beverage warmer.
JP 2000-20951 A JP 2000-159946 A JP 2002-132159 A

  The problem to be solved by the present invention is that heat resistance, even when stored in a warm beverage warmer, the films do not stick to each other, the quality balance is particularly good for labels, and the PET bottles by liquid density separation method And providing a heat-shrinkable olefin film that can be easily separated.

  In the present invention, the front and back layers are a resin composition mainly composed of a cyclic olefin copolymer resin having a glass transition temperature of 60 ° C. to 90 ° C., and the intermediate layer is a laminate comprising a resin composition mainly composed of an olefin resin. The film has a thermal shrinkage rate of 30% or more in at least one direction when immersed in warm water at 80 ° C. for 10 seconds, and has a glass transition point of 50 to 90 ° C. on at least one side of the film. The heat-shrinkable olefin film is provided with a transparent coating layer using an acrylic resin as a vehicle.

According to the present invention, it is possible to obtain a heat-shrinkable olefin film having a good quality balance especially for labels without causing sticking between bottles even when stored in a hot drink warmer. Further, when the label is light and the specific gravity is less than 1, it has an advantage that it can be separated by a specific gravity separation method at the time of recycling.

DETAILED DESCRIPTION OF THE INVENTION The cyclic olefin-based resin as the main component of the front and back layers of the present invention is a general generic name, and specifically, (a) a ring-opening (co) polymer of cyclic olefin is required. (B) Addition (co) polymer of cyclic olefin, (c) Random copolymer of cyclic olefin and α-olefin such as ethylene, propylene, (d) (a) to ( Examples include graft-modified products obtained by modifying c) with unsaturated carboxylic acids or derivatives thereof. The cyclic olefin is not particularly limited, and examples thereof include norbornene and tetracyclododecene. Specifically, this cyclic olefin copolymer resin may be exemplified by the trade name “ZEONOR” manufactured by Zeon Corporation, the product name “Apel” manufactured by Mitsui Chemicals, Inc., and the product name “Topas” manufactured by Ticona. it can. The specific gravity of the cyclic olefin resin is generally 1.00 to 90.

  The glass transition temperature of the cyclic olefin resin is desirably 50 to 90 ° C, more desirably 60 to 80 ° C. If it is less than 50 ° C., the natural shrinkage tends to be high, and if it exceeds 90 ° C., the thermal shrinkage rate in the main stretching direction at a steam shrinker temperature of about 70 to 90 ° C. tends to be too small.

The storage elastic modulus (E ′) at 90 ° C. obtained by dynamic viscoelasticity measurement (frequency 1 Hz, strain 0.1%) of the cyclic olefin resin is desirably 1.0 × 10 ^{7 to} 1.0 × 10 ^9. Pa, more preferably 7.0 × 10 ^{7 to} 7.0 × 10 ⁸ Pa. When the storage elastic modulus E ′ at 70 ° C. is lower than 1.0 × 10 ⁷ Pa, since the difference in hardness between the film surface and the transparent coating layer is large in the hot beverage warmer, the transparent coating layer is likely to crack. The resulting film is undesirably practically used because its natural shrinkage (slightly higher than normal temperature, for example, shrinkage of the film in summer) increases dimensional stability. On the other hand, if it is higher than 1.0 × 10 ⁹ , low-temperature stretching becomes difficult and it becomes difficult to obtain good shrinkage characteristics.

  Further, hydrocarbon resins may be added to the front and back layers. By adding hydrocarbon resins, the effect of improving the glossiness of the film surface can be obtained. The addition amount of the hydrocarbon resins is desirably 1 to 25 parts by weight, more desirably 5 to 20 parts by weight with respect to 100 parts by weight of the cyclic olefin resin. When the addition amount is less than 1% by weight, the effect of addition is small, and when it exceeds 25 parts by weight, the film tends to be easily formed. As used herein, the hydrocarbon resins are aliphatic hydrocarbon resins, aromatic hydrocarbon resins, alicyclic hydrocarbon resins, or hydrogenated products thereof generally called petroleum resins, or rosin, Examples include rosin esters and terpene resins.

  Furthermore, the above-mentioned front and back layers are provided with a weather resistance stabilizer, heat resistance stabilizer, antistatic agent, antiblocking agent, lubricant, nucleating agent, plasticizer, antiaging agent, hydrochloric acid absorbent as long as the object of the present invention is not impaired. In addition, additives such as antioxidants may be appropriately mixed.

  The olefin resin used for the intermediate layer of the present invention is preferably a low-density polyolefin resin from the viewpoints of shrinkage characteristics, stretching characteristics and economy. Examples of the resin include low density polyethylene (hereinafter abbreviated as “LDPE”), linear low density polyethylene (hereinafter abbreviated as “LLDPE”), ethylene-vinyl acetate copolymer and saponified product thereof, An ionomer resin, a propylene-ethylene copolymer, a propylene-ethylene-butene-1 copolymer, a propylene-hexene copolymer, an ethylene-α-olefin copolymer, and a reactor type polypropylene elastomer, or two or more of these A mixture is mentioned.

The density of the olefin resin is less than 0.940 g / cm ³ is good, less than 0.86~0.93g / cm ³ is more preferable. When the density is 0.94 g / cm ³ or more, the specific gravity of the laminated film with the transparent coating layer tends to be 0.99 or more, and when the printed film is used for coating PET bottles, It may be difficult to efficiently separate by the specific gravity separation method. Moreover, if it is less than 0.86 g / cm ³ , the resulting laminated film tends to be low.

  Furthermore, the melting temperature of the olefin resin measured by a differential scanning calorimeter (DSC) is desirably 90 to 170 ° C, more desirably 130 to 160 ° C. When the melting temperature is 90 ° C. or lower, the heat resistance of the film becomes insufficient, and for example, when blocking occurs when a bottle is mounted or in a bottle warmer, the film tends to break. On the other hand, when the temperature exceeds 170 ° C., it is difficult to stretch at low temperature, and good low temperature shrinkability cannot be obtained.

  Hydrocarbon resins may be added to the intermediate layer composition mainly composed of the olefin resin for the purpose of improving the shrinkage characteristics. The ratio of the hydrocarbon resin is preferably 1 to 40 parts by weight, more preferably 10 to 30 parts by weight, based on 100 parts by weight of the olefin resin. When the addition of hydrocarbon resin is less than 10 parts by weight, there is no effect. When the addition is more than 40 parts by weight, the hydrocarbon resin aggregates at the lamination interface, resulting in extremely low interlayer adhesion and a film with poor impact resistance. Easy to be.

  Furthermore, the olefin-based resin has an antioxidant, an ultraviolet absorber, a light stabilizer, a compatibilizing agent, in order to improve the molding processability and physical properties of the heat-shrinkable film, as long as the object of the present invention is not impaired. It is also possible to add additives such as nucleating agents, plasticizers, flame retardants, lubricants, and modifiers.

In the present invention, the thickness ratio of the front and back layers and the intermediate layer may be set so as not to impair each of the above actions, but in order to express more effectively, the front and back layers mainly composed of the above cyclic olefin resin and The olefin resin is preferably 1/6/1 to 1/2/1. When the ratio of the intermediate layer is larger than 1/6/1, the natural shrinkage tends to be large and the dimensional stability is deteriorated, and the film tends to have a low waist. On the other hand, when the ratio of the intermediate layer is smaller than 1/2/1, the specific gravity of the film provided with the transparent coating layer may be higher than 0.99 g / cm ³ .

  In the present invention, the main component of the vehicle contained in the transparent coating layer is an acrylic resin such as methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate or the like. Copolymers or copolymers of these acrylic monomers as the main component, vinyl acetate that can be copolymerized with these, styrene, etc., and the above-mentioned polymers or copolymers as the main components, ethylene-vinyl acetate copolymers, etc. A blended composition may be mentioned.

  Further, the acrylic resin component contained in the transparent coating layer may be used by appropriately dissolving in a solvent, or may be used in an emulsion type. Examples of the acrylic resin solvent include ethyl acetate, toluene, methyl ethyl ketone, and the like. To the acrylic resin composition used for the transparent coating layer, additives such as a heat stabilizer, an antioxidant, an ultraviolet absorber, a light stabilizer, and inorganic particles are added as long as the object of the present invention is not impaired. May be.

  The glass transition point of the acrylic resin component is desirably 60 to 100 ° C, and more desirably 70 to 90 ° C. When the glass transition point is 60 ° C. or lower, the film is inferior in heat resistance, so that the film is likely to block when kept warm in the bottle warmer. On the other hand, when the temperature is 100 ° C. or higher, the hardness at the shrinkage temperature of the transparent coating layer is often high, and when the film is attached to the bottle by heat shrinkage and kept warm in the bottle warmer, the transparent coating layer is cracked. Value may be significantly impaired.

  In the present invention, the thickness ratio between the laminated film and the transparent coating layer is preferably 100/1 to 10/1, and more preferably 80/1 to 20/1. When the ratio of the transparent coating layer is lower than 100/1, the effect on heat resistance is thin, and there is a possibility that the films stick to each other in the bottle warmer. On the other hand, when the ratio of the transparent coating layer is larger than 20/1, the transparent coating layer hinders the heat shrink property of the film and it is difficult to obtain sufficient shrink property, and the transparent coating layer is cracked when the bottle is attached. There is a problem of detracting from commercial value.

  The film of the present invention can be produced by a known method. The shape of the film may be either flat or tube-like, but it is more flat from the viewpoint of productivity (a few products can be taken in the width direction of the original film) and printing on the inner surface. desirable. As a production method in the case of a flat shape, for example, a resin is melted using a plurality of extruders, co-extruded from a T die, cooled and solidified with a chilled roll, roll-stretched in the vertical direction, and tenter-stretched in the horizontal direction. An example is a method of obtaining a film by winding, annealing, cooling, and winding with a winder (when printing is performed, the surface may be subjected to corona discharge treatment). Moreover, the method of cutting open the film manufactured by the tubular method and making it flat is also applicable.

  The stretching ratio is 2-10 times in the longitudinal direction, 2-10 times in the transverse direction, preferably 3-6 times in the longitudinal direction, and about 3-6 times in the transverse direction in applications that shrink in two directions, such as for overlap. Is desirable. On the other hand, in applications that shrink in one direction, such as for shrink labels, the direction corresponding to the main shrinkage direction is 2 to 10 times, preferably 4 to 8 times, and the direction perpendicular to it is 1 to 2 times (1x is In the sense that the film is not stretched), it is desirable to select a magnification ratio of 1.1 to 1.5 times, which is substantially in the category of uniaxial stretching. Since the film obtained at a normal biaxial stretching ratio also has a large thermal shrinkage rate in the direction perpendicular to the main shrinkage direction, for example, when used as a shrinkage label, the film also extends in the height direction of the container when it is attached to the container. A so-called vertical shrinkage phenomenon that shrinks by heat occurs, which is not desirable.

  The present invention will be described below with reference to examples. In addition, the measured value and evaluation which are shown to an Example were performed as follows. Here, the take-up (flow) direction of the laminated film is referred to as a “longitudinal” direction, and a direction perpendicular thereto is referred to as a “lateral” direction.

[Heat shrinkage]
The film was cut into a size of 100 mm in length and 100 mm in width, and immersed in a hot water bath at 80 ° C. for 10 seconds, and the amount of shrinkage was measured. The thermal shrinkage rate was expressed as a ratio (%) of the shrinkage amount to the original size before shrinkage in the lateral direction.

[Lamination ratio] (Film / Transparent coating layer)
The cross section of the film provided with the transparent coating layer was observed with an optical microscope, and the ratio of the transparent coating layer was set to 1 to calculate the layer ratio of the film.

[Heat resistance evaluation]
Two bottles equipped with this heat shrink label in YOSHIKIN's “PET BOTTLE WARMER” are kept horizontally stacked and left in contact for 24 hours. The state was observed visually.

[Surface appearance evaluation]
As in the above heat resistance evaluation, two bottles equipped with this heat shrink label in a “PET bottle warmer” manufactured by YOSHIKIN Co., Ltd. are kept in a horizontal state and left in contact for 24 hours, and then a transparent coating layer Cracks and sticking marks were visually observed. The case where there was no problem in practical use was evaluated as ○, and the case where there was a problem in practical use was evaluated as ×.

[specific gravity]
Based on JIS K7112, specific gravity was computed by ratio of the density of the film which gave the coating measured by the density gradient tube method, and the density of the water in the temperature of 23 degreeC.

(Example 1)
10 parts by weight of hydrogenated terpene resin (Clearon P150 from Yashara Chemical Co., Ltd.) with respect to 100 parts by weight of a random copolymer of ethylene and cyclic olefin (Mitsui Chemical Co., Ltd., APEL8008T, Tg: 75 ° C.) serving as the front and back layers. 60 parts by weight of an ethylene-propylene rubber (Idemitsu Petrochemical Co., Ltd. PER T310E: Tm: 160 ° C.) and low density polyethylene (Nippon Polychem Co., Ltd. LF440HB, Tm: 113 ° C.) ) A polymer composition obtained by blending 10 parts by weight of an aliphatic saturated hydrocarbon resin (Arcon P140, manufactured by Arakawa Chemical Co., Ltd.) with 40 parts by weight, respectively, and melt-kneading each using a same-direction twin screw extruder, and pellets of the composition Got. This composition was put into separate extruders, then co-extruded from a three-layer die so that the thickness of each layer would be front / back layer / intermediate layer / front / back layer = 1/4/1, and taken and solidified by a 50 ° C. cast roll. Thus, an unstretched laminated sheet having a width of 200 mm and a thickness of 200 μm was obtained. In a tenter stretching facility, the film was stretched 4 times in a uniaxial direction at a temperature of 90 ° C. to prepare a heat-shrinkable film having a thickness of 50 μm. A transparent coating layer [trade name “LR469, Tg: 77 ° C.”, manufactured by Mitsubishi Rayon Co., Ltd.] is applied to one surface of the obtained base film with an acrylic resin as a vehicle by a Mayer bar coater. Formed. When the thickness of the transparent coating layer was measured, it was 1 μm, and the thickness ratio of the film to the transparent coating layer was 50/1. The transparent coating layer was on the outside and the base film was rolled into a cylindrical shape so that the width direction was the circumferential direction, and both ends were bonded with an organic solvent (tetrahydrofuran) to obtain a cylindrical shrinkable label. The obtained label was placed on the bottle, and then attached with a shrinker at a temperature of 70 to 90 ° C. to obtain a bottle attachment film. As a result of heat resistance and surface appearance evaluation, the surface appearance was good without sticking.

(Example 2)
10 parts by weight of hydrogenated terpene resin (Clearon P150 from Yashara Chemical Co., Ltd.) with respect to 100 parts by weight of a random copolymer of ethylene and cyclic olefin (Mitsui Chemical Co., Ltd., APEL8008T, Tg: 75 ° C.) serving as the front and back layers. 60 parts by weight of an ethylene-propylene rubber (Idemitsu Petrochemical Co., Ltd. PER T310E: Tm: 160 ° C.) and low density polyethylene (Nippon Polychem Corp. LF440HB, Tm: 113 ° C.) ) A polymer composition obtained by blending 10 parts by weight of an aliphatic saturated hydrocarbon resin (Arakawa Chemical Co., Ltd. Alcon P140) with 40 parts by weight, an ethylene-propylene-brene terpolymer (Sun Allomer Co., Ltd.) as an intermediate layer ) Made Adsy5C30F, Tm: 146 ° C.) 50 parts by weight and low density polyethylene (Japan A polymer composition obtained by blending 10 parts by weight of an aliphatic saturated hydrocarbon resin (Arcon P140, manufactured by Arakawa Chemical Co., Ltd.) with 50 parts by weight of LF440HB manufactured by Polychem Co., Ltd., respectively, using a same-direction twin screw extruder. The mixture was melt-kneaded to obtain composition pellets. This composition was put into separate extruders, then co-extruded from a three-layer die so that the thickness of each layer would be front / back layer / intermediate layer / front / back layer = 1/4/1, and taken and solidified by a 50 ° C. cast roll. Thus, an unstretched laminated sheet having a width of 200 mm and a thickness of 200 μm was obtained. This was stretched 4 times in a uniaxial direction at a temperature of 90 ° C. in a tenter stretching facility to prepare a heat-shrinkable film having a thickness of 50 μm. A transparent coating layer [Mitsubishi Rayon Co., Ltd., trade name “LR90, Tg: 85 ° C.” applied on one surface of the obtained base film with an acrylic resin vehicle as a transparent coating layer] Formed. When the thickness of the transparent coating layer was measured, it was 2 μm, and the thickness ratio of the film to the transparent coating layer was 25/1. The transparent coating layer was on the outside, and the base film was rolled into a cylindrical shape so that the width direction was the circumferential direction, and both ends were bonded with an organic solvent (tetrahydrofuran) to obtain a cylindrical shrinkable label. The obtained label was placed on the bottle, and then attached with a shrinker at a temperature of 70 to 90 ° C. to obtain a bottle attachment film. As a result of heat resistance evaluation, the surface appearance was good without sticking.

(Comparative Example 1)
10 parts by weight of hydrogenated terpene resin (Clearon P150 from Yashara Chemical Co., Ltd.) with respect to 100 parts by weight of a random copolymer of ethylene and cyclic olefin (Mitsui Chemical Co., Ltd., APEL8008T, Tg: 75 ° C.) serving as the front and back layers. 60 parts by weight of an ethylene-propylene rubber (Idemitsu Petrochemical Co., Ltd. PER T310E: Tm: 160 ° C.) and low density polyethylene (Nippon Polychem Corp. LF440HB, Tm: 113 ° C.) ) A polymer composition obtained by blending 10 parts by weight of an aliphatic saturated hydrocarbon resin (Arcon P140, manufactured by Arakawa Chemical Co., Ltd.) with 40 parts by weight, respectively, and melt-kneading each using a same-direction twin screw extruder, and pellets of the composition Got. This composition was put into separate extruders, then co-extruded from a three-layer die so that the thickness of each layer would be front / back layer / intermediate layer / front / back layer = 1/4/1, and taken and solidified by a 50 ° C. cast roll. Thus, an unstretched laminated sheet having a width of 200 mm and a thickness of 200 μm was obtained. In a tenter stretching facility, the film was stretched 4 times in a uniaxial direction at a temperature of 90 ° C. to prepare a heat-shrinkable film having a thickness of 50 μm. A transparent coating layer [Mitsubishi Rayon Co., Ltd., trade name “LR1065, Tg: 105 ° C.] applied on one surface of the obtained base film with an acrylic resin as a vehicle is coated with a transparent coating layer. Formed. When the thickness of the transparent coating layer was measured, it was 1 μm, and the thickness ratio of the film to the transparent coating layer was 50/1. The transparent coating layer was on the outside, and the base film was rolled into a cylindrical shape so that the width direction was the circumferential direction, and both ends were bonded with an organic solvent (tetrahydrofuran) to obtain a cylindrical shrinkable label. The obtained label was placed on the bottle, and then attached with a shrinker at a temperature of 70 to 90 ° C. to obtain a bottle attachment film. When the heat resistance was evaluated, it was not after sticking, but the surface transparent coating agent was cracked and the appearance was remarkably impaired.

(Comparative Example 2)
10 parts by weight of hydrogenated terpene resin (Clearon P150, Yashara Chemical Co., Ltd.) with respect to 100 parts by weight of a random copolymer of ethylene and cyclic olefin (Mitsui Chemicals, Inc., APEL8008T, Tg: 75 ° C.) serving as the front and back layers. 60 parts by weight of an ethylene-propylene rubber (Idemitsu Petrochemical Co., Ltd. PER T310E: Tm: 160 ° C.) and low density polyethylene (Nippon Polychem Co., Ltd. LF440HB, Tm: 113 ° C.) ) A polymer composition obtained by blending 10 parts by weight of an aliphatic saturated hydrocarbon resin (Arcon P140, manufactured by Arakawa Chemical Co., Ltd.) with 40 parts by weight, respectively, and melt-kneading each using a same-direction twin screw extruder, and pellets of the composition Got. This composition was put into separate extruders, then co-extruded from a three-layer die so that the thickness of each layer would be front / back layer / intermediate layer / front / back layer = 1/4/1, and taken and solidified by a 50 ° C. cast roll. Thus, an unstretched laminated sheet having a width of 200 mm and a thickness of 200 μm was obtained. In a tenter stretching facility, the film was stretched 4 times in a uniaxial direction at a temperature of 90 ° C. to prepare a heat-shrinkable film having a thickness of 50 μm. A transparent coating layer [Mitsubishi Rayon Co., Ltd., trade name “LR675, Tg: 45 ° C.” applied on one surface of the obtained base film with an acrylic resin vehicle is applied with a Mayer bar coater. Formed. When the thickness of the transparent coating layer was measured, it was 1 μm, and the thickness ratio of the film to the transparent coating layer was 50/1. The transparent coating layer was on the outside, and the base film was rolled into a cylindrical shape so that the width direction was the circumferential direction, and both ends were bonded with an organic solvent (tetrahydrofuran) to obtain a cylindrical shrinkable label. The obtained label was placed on the bottle, and then attached with a shrinker at a temperature of 70 to 90 ° C. to obtain a bottle attachment film. When heat resistance evaluation and surface observation were performed, cracks did not occur in the surface transparent coating agent, but sticking between the films occurred, and when the films were peeled off, sticking marks remained and the appearance was remarkably impaired.

(Comparative Example 3)
10 parts by weight of hydrogenated terpene resin (Clearon P150, Yashara Chemical Co., Ltd.) with respect to 100 parts by weight of a random copolymer of ethylene and cyclic olefin (Mitsui Chemicals, Inc., APEL8008T, Tg: 75 ° C.) serving as the front and back layers. 60 parts by weight of an ethylene-propylene rubber (Idemitsu Petrochemical Co., Ltd. PER T310E: Tm: 160 ° C.) and low density polyethylene (Nippon Polychem Co., Ltd. LF440HB, Tm: 113 ° C.) ) A polymer composition obtained by blending 10 parts by weight of an aliphatic saturated hydrocarbon resin (Arcon P140, manufactured by Arakawa Chemical Co., Ltd.) with 40 parts by weight, respectively, and melt-kneading each using a same-direction twin screw extruder, and pellets of the composition Got. This composition was put into separate extruders, then co-extruded from a three-layer die so that the thickness of each layer would be front / back layer / intermediate layer / front / back layer = 1/4/1, and taken and solidified by a 50 ° C. cast roll. Thus, an unstretched laminated sheet having a width of 200 mm and a thickness of 200 μm was obtained. In a tenter stretching facility, the film was stretched 4 times in a uniaxial direction at a temperature of 90 ° C. to prepare a heat-shrinkable film having a thickness of 50 μm. A transparent coating layer [Mitsubishi Rayon Co., Ltd., trade name “LR637, Tg: 42 ° C.” applied on one surface of the obtained base film with an acrylic resin as a vehicle is coated with a Mayer bar coater. Formed. When the thickness of the transparent coating layer was measured, it was 0.25 μm, and the thickness ratio of the film to the transparent coating layer was 200/1. The transparent coating layer was on the outside, and the base film was rolled into a cylindrical shape so that the width direction was the circumferential direction, and both ends were bonded with an organic solvent (tetrahydrofuran) to obtain a cylindrical shrinkable label. The obtained label was placed on the bottle, and then attached with a shrinker at a temperature of 70 to 90 ° C. to obtain a bottle attachment film. When heat resistance evaluation and surface observation were performed, cracks were observed in the surface transparent coating agent, and sticking between films occurred. When the films were peeled off, sticking marks remained and the appearance was remarkably impaired.

  From Table 1, it can be seen that the heat-shrinkable films in Examples 1 and 2 having the components specified in the present invention and within the specified range are excellent in heat resistance, surface appearance and shrinkage rate. On the other hand, it can be seen that Comparative Examples 1 and 2, which are outside the range defined in the present invention, are inferior in one or more characteristics among heat resistance, surface appearance and shrinkage.

Claims (4)

The front and back layers consist of a resin composition whose main component is a cyclic olefin copolymer resin having a glass transition temperature of 60 ° C. to 90 ° C., and the intermediate layer is a laminate composed of a resin composition whose main component is an olefin resin. A heat-shrinkable olefin-based laminated film, which is a laminated film obtained by coating a transparent coating layer having an acrylic resin having a glass transition point of 50 to 90 ° C. as a vehicle on at least one side of the laminated film. 2. The heat-shrinkable olefin-based laminated film according to claim 1, wherein a thickness ratio of the laminated film and the transparent coating layer is 100/1 to 10/1. 2. The heat-shrinkable olefin-based laminated film according to claim 1, wherein a thickness ratio of each layer of the laminated film is front / back layer / intermediate layer / front / back layer = 1/6/1 to 1/2/1. 2. The heat-shrinkable polyolefin-based laminated film according to claim 1, wherein the specific gravity of all the films provided with the transparent coating layer is 0.99 or less.