JP2002234115A - Multilayer heat shrinkable film and shrinkable label and container using the same - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To have a light weight, a waist, less natural shrinkage near room temperature, dimensional stability, good shrinkability from a relatively low temperature range, and moderate shrinkage stress, In addition, while maintaining the property of being easily bonded to an organic solvent and being easily processed into a cylindrical label, there is no whitening due to the grease of the hand when shrinking, and a smoothness that does not cause a practical problem even if subjected to corona discharge treatment. Provided are a heat-shrinkable film and a cylindrical heat-shrinkable label which can maintain the property. SOLUTION: Front and back film layers mainly composed of a resin composition obtained by blending 60 to 150 parts by weight of a linear low-density polyethylene with 100 parts by weight of a cyclic olefin resin, and a propylene-α-olefin random copolymer or A multilayer heat-shrinkable film comprising at least three or more layers having an intermediate film layer formed of a resin composition containing a copolymer as a main component. Further, a cylindrical shrinkable label produced from the multilayer heat shrinkable film and a label mounting container to which the cylindrical shrinkable label is mounted are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer heat-shrinkable film which has little natural shrinkage near room temperature, excellent dimensional stability and excellent heat shrinkage characteristics from a relatively low temperature range, low specific gravity, and does not cause whitening due to fingerprints during heat shrinkage. About the film. The present invention also relates to a cylindrical shrinkable label produced from the film and a container in which the multilayer heat shrinkable cylindrical label is brought into close contact with a container by heating using the heat shrinkage of the film.

[0002]

2. Description of the Related Art Soft drinks such as juice are sold in bottles or PET bottles. At this time, a heat-shrinkable label having an inner surface printed thereon is often attached to the outside of the container in order to differentiate the product from other products and improve the visibility of the product. Label material is polystyrene,
Examples include polyester, polyvinyl chloride, and polyolefin.

When the container is a PET bottle, the PET bottle collected after use for recycling is often regenerated into flakes or pellets. The outline of this step will be described below. The collected PET bottles (usually with a cap made of polyethylene or the like and a heat-shrinkable label) are hand-operated, weight-separated, X
It is sorted out from other containers such as glass bottles, cans, and PVC bottles by line inspection and the like. Next, the PET bottle is several mm to 1 mm.
The heat-shrinkable label pulverized product having a specific gravity of less than 1 or a cap having a specific gravity of less than 1 is removed by pulverizing into a 0 mm square. Further, the heat-shrinkable crushed label having a specific gravity of 1 or more is removed by the wind separator. From the pulverized PET bottle thus obtained, desired regenerated pet flakes or regenerated pet pellets are obtained.

[0004] The above-mentioned specific gravity separators include those in which a pulverized body is placed in water and floated on water (heat-shrinkable labels or caps having a specific gravity of less than 1) and those which sink in water (heat-shrinkable labels with a specific gravity of 1 or more). And crushed PET bottles)
A wind separator is a device that spreads a crushed body and blows the heat-shrinkable crushed label body against the wind from below. According to each principle, the specific gravity separator has a large processing capacity per unit time, while the wind separator has a small capacity. For this reason, a heat-shrinkable label having a specific gravity of less than 1 that can be removed by a specific gravity separator has been demanded.

However, among the above label materials, polystyrene labels have a large natural shrinkage rate, polyester labels have a high shrinkage rate upon heat shrinkage, and all of them are difficult to handle. And other harmful gases.
In addition, since the specific gravity of each label is greater than 1, there is a problem that it cannot be separated by a specific gravity separator in the recycling process. On the other hand, although the polyolefin label has a specific gravity of less than 1, there is a problem that it cannot be manufactured by center sealing with an organic solvent because of insufficient rigidity and gloss. Furthermore, since the polyolefin label does not shrink unless the heat shrink temperature is increased, there is a problem that it does not have heat resistance, for example, it cannot be used for non-heat-resistant PET bottles.

[0006] In order to overcome these disadvantages,
The applicants have previously developed and invented a heat-shrinkable label disclosed in JP-A-2000-159946. That is, the shrinkable label disclosed in this publication is 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 are laminated.

[0007]

SUMMARY OF THE INVENTION The heat-shrinkable label according to the present invention has solved many of the problems to be solved for conventional heat-shrinkable labels. However, the heat-shrinkable label according to the present invention has a serious practical disadvantage due to the fact that the amorphous resin is a cyclic olefin resin. That is, shrink films are generally very often touched by humans before they are attached to a container or the like and shrunk, but in the case of this shrink film, the cyclic olefin resin lacks grease resistance, so that the contact A phenomenon occurs in which the fingerprint part whitens after contraction (accurately, a fine crack is generated and looks white). Further, when corona discharge treatment is performed to impart adhesion to printing ink, there is a disadvantage that lubricity is deteriorated.

The problem to be solved by the present invention is that the heat shrinkable label has the required functions, that is, it is lightweight, stiff, has little natural shrinkage near room temperature, and has dimensional stability and a relatively low temperature range. It has a good shrinkage property, has an appropriate shrinkage stress, and maintains the property of being able to seal the center with an organic solvent when processed into a label, does not whiten when shrinking, and has corona discharge. An object of the present invention is to provide a heat-shrinkable film that can maintain a degree of lubricity that does not cause a practical problem even when subjected to a treatment. Another object of the present invention is to provide a heat-shrinkable label having such characteristics, and further to provide a beautifully-fitted container in which the heat-shrinkable label is tightly mounted.

[0009]

In order to solve the above-mentioned problems, the present invention relates to 1. A resin composition obtained by blending 60 to 150 parts by weight of a linear low-density polyethylene with 100 parts by weight of a cyclic olefin resin. Front and back film layers as components,
A propylene-α-olefin random copolymer or an intermediate film layer formed of a resin composition containing the copolymer as a main component and a multilayer heat-shrinkable film having at least three layers laminated,

[0010] 2. Claims 1. A cylindrical shrinkable label made from the multilayer heat shrinkable film of claim 1,
3. Furthermore, the object was successfully achieved by constituting a label mounting container on which the cylindrical shrinkable label according to claim 2 was mounted.

That is, in the present invention,
No. 59946, a multilayer laminated heat-shrinkable film obtained by laminating at least three layers of a film mainly composed of a cyclic olefin-based resin and a film mainly composed of a propylene-α-olefin random copolymer. The heat-shrinkable label produced using the multilayer laminated heat-shrinkable film, which is based on the properties of the film mainly composed of the cyclic olefin-based resin forming the front and back film layers, has improved whitening and printability at the time of mounting. Defects such as a decrease in lubricity due to corona discharge treatment performed for the purpose of the present invention can be directly applied to a cyclic olefin-based resin by forming a film mainly composed of a cyclic olefin-based resin constituting the multilayer laminated heat-shrinkable film of the prior art. Replace with a film consisting of a blended polymer whose main component is a resin composition blended with linear low density polyethylene As a result, these problems can be solved without losing the required functions and features required for the heat-shrinkable label provided by using the film containing the cyclic olefin-based resin of the preceding invention as a main component. It was done.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The cyclic olefin-based resin as one of the constituent components for forming the front and back film layers and the like of the present invention is described in JP-A-2000-159946. ) Random copolymers of ethylene or propylene with cyclic olefins (eg, norbornene and derivatives thereof and tetracyclododecene and derivatives thereof); (b) ring-opening polymers of the cyclic olefins and copolymers thereof; Examples include the hydrogenated polymer of the polymer (b) and the graft-modified products (a) to (c) of (d) unsaturated carboxylic acids and derivatives thereof. The specific gravity of the cyclic olefin resin is generally 1.00 to 1.0.
6.

The glass transition temperature of the cyclic olefin resin is preferably from 50 to 100 ° C., more preferably from 60 to 90 ° C. If it is less than 50 ° C., the natural shrinkage tends to be too large, and if it exceeds 100 ° C., the heat shrinkage in the main shrinkage direction in a low temperature region tends to be too small.

The density of the linear low-density polyethylene of the present invention, which is a component for forming a front and back film layer made of a blend polymer by blending with a cyclic olefin resin, is preferably 0.910 to 0.935 g / cm ³ , More preferably, it is 0.912 to 0.930 g / cm ³ , and still more preferably 0.915 to 0.925 g / cm ³ . When the density is less than 0,910 g / cm ³ , the heat resistance of the film surface decreases, and the surface becomes sticky when heat is applied. For example, when used as a shrinkable label, the containers are placed on a mounting line. The phenomenon of blocking tends to occur easily. On the other hand, when the density exceeds 0.935 g / cm ³ , the heat resistance is improved, but the film cannot be stretched unless the temperature is high at the time of stretching, and the whole film tends to be whitish and has a poor haze.

The linear low-density polyethylene has a melt flow rate (MFR) (190 ° C., 21.18 N).
Is preferably 0.2 to 30 g / 10 min, more preferably 0.5 to 25 g / 10 min, and still more preferably 1.0 to 20 g / 10 min. MFR 0.2g
If it is less than / 10 min, kneading and dispersion with the cyclic olefin-based resin will be poor, and a homogeneous blend polymer cannot be obtained, resulting in a film having a poor surface state. on the other hand,
If the MFR exceeds 30 g / 10 min, the melt viscosity becomes too low, so that the molten polymer film discharged from the T-die cannot be continuously cast, cannot be wound with a film having a constant thickness and a constant width, and the film cannot be formed. There is a tendency that the strength and other physical properties of the film are reduced and the specified value cannot be achieved.

In the linear low-density polyethylene, the α-olefin copolymerized with ethylene has 4 to 4 carbon atoms.
12 are preferable, and among these, a binary copolymer of ethylene and 1-butene or 1-hexene;
Or a terpolymer of ethylene, 1-butene and 1-hexene is more preferred. Among these, a binary copolymer of ethylene and 1-butene is more preferred.

The amount (blend ratio) of the linear low-density polyethylene blended with the cyclic olefin resin is 60 to 150 parts by weight, preferably 65 to 120 parts by weight, per 100 parts by weight of the cyclic olefin resin. Preferably it is 70 to 90 parts by weight. When the amount is less than 60 parts by weight, the whitening phenomenon during shrinkage cannot be completely suppressed, and when corona discharge treatment is performed, it is difficult to maintain lubricity, which is not preferable. On the other hand, if it exceeds 150 parts by weight, transparency and gloss will be inferior, and the adhesive performance will be reduced due to the improvement in solvent resistance, and the center seal will be performed under mild conditions using an organic solvent. You will not be able to do it. The resin composition of the front and back film layers, that is, the type (including the difference in MFR) of the cyclic olefin-based resin and the linear low-density polyethylene of the front and back film layers may be the same or different. Further, two or more of them may be included. Also, the resin composition ratio may be the same or different.

Further, it is more desirable to add a hydrocarbon resin to the resin composition in which the cyclic olefin resin forming the front and back film layers and the linear low-density polyethylene are blended. The effect of improving the glossiness of the film surface is obtained by adding the hydrocarbon resin. The addition amount of the hydrocarbon resin is preferably 2 to 20 parts by weight based on 100 parts by weight of the blend polymer composition of the cyclic olefin resin and the linear low-density polyethylene,
More preferably, it is 5 to 15 parts by weight. If the addition amount is less than 2 parts by weight, the effect of the addition is small, and if it exceeds 20 parts by weight, the film becomes hard, brittle, and easily tearable, and the film surface tends to be sticky and cause blocking. is there.

The hydrocarbon resins include those generally referred to as petroleum resins such as aliphatic hydrocarbon resins, aromatic hydrocarbon resins, alicyclic hydrocarbon resins, and hydrogenated products thereof, and rosins. Rosin esters, terpene resins and the like are mentioned, and hydrogenated products thereof are particularly preferable.

In the resin composition for forming the front and back film layers, an antistatic agent, an antiblocking agent, a lubricant, an ultraviolet inhibitor, a stabilizer, a coloring agent, and the like, within a range not impairing the essence of the present invention.
Alternatively, a known resin such as another resin may be appropriately added.

The propylene-α-olefin random copolymer used in the intermediate film layer of the present invention is a copolymer containing propylene as a main component, and the α-olefin has 2 to 12 carbon atoms (excluding 3). For example, those composed of ethylene, 1-butene, 1-hexene, 1-octene, 1-decene and the like are preferable, and the copolymer may contain two or more α-olefins. Also, a mixture of different types (including differences in MFR) of propylene-α-olefin random copolymers may be used. As the propylene-α-olefin random copolymer,
More preferably, it is a propylene-ethylene random copolymer. More preferably, the ethylene content is 2 to 7 mol%
Is a propylene-ethylene random copolymer.

It is more desirable to further add a hydrocarbon resin to the intermediate film layer. That is, the effect of increasing the heat shrinkage can be obtained by adding hydrocarbon resins. The addition amount of hydrocarbon resins
The amount is preferably 5 to 70 parts by weight, more preferably 35 to 55 parts by weight, based on 100 parts by weight of the propylene-α-olefin random copolymer. If the amount is less than 5 parts by weight, the effect of the addition is small, and if it exceeds 70 parts by weight, the film becomes hard and brittle, resulting in a film having low strength and poor physical properties,
In addition, the resin is wrapped around the screw of the extruder during film production, so that so-called bridging is easily caused, the discharge pressure fluctuates, and there is a tendency that stable discharge becomes difficult. The hydrocarbon resins are as described above.

It is more desirable to add a linear low-density polyethylene to the intermediate film layer. By adding the linear low-density polyethylene, the impact resistance of the film is improved.
In the film having the layer structure, an effect of improving the delamination strength is obtained in combination with the linear low-density polyethylene of the front and back film layers. The amount of linear low-density polyethylene added is 100% of the blended resin composition of the propylene-α-olefin random copolymer and the hydrocarbon resin.
The amount is preferably 2 to 30 parts by weight, more preferably 5 to 20 parts by weight with respect to parts by weight. When the addition amount is less than 2 parts by weight, the effect of the addition is small, and when it exceeds 30 parts by weight, the transparency of the film is reduced, and the rigidity of the film is reduced and the film becomes soft. In this case, the mounting performance of the automatic mounting machine is degraded, and a trouble tends to occur. The linear low-density polyethylene is as described above.

It is desirable to further add a rubber component to the intermediate film layer. By adding the rubber component,
This is because the effect of improving the impact resistance of the film can be obtained. The amount of the rubber component is preferably 2 to 30 parts by weight based on 100 parts by weight of the blend resin composition of the propylene-α-olefin random copolymer and the hydrocarbon resin.
Parts by weight, more preferably 5 to 20 parts by weight. When the addition amount is less than 2 parts by weight, the effect of the addition is small,
If it exceeds 30 parts by weight, the transparency of the film tends to decrease. The rubber component is not particularly limited. For example, ethylene-propylene rubber, ethylene-propylene rubber
Examples thereof include propylene-diene rubber and ethylene-butene rubber. Among them, ethylene-propylene rubber is more preferable.

To the intermediate film layer, a known material such as an antistatic agent, a lubricant, an ultraviolet ray inhibitor, a stabilizer, a colorant, or another resin is appropriately added within a range not to impair the essence of the present invention. May be.

The composition ratio of the thickness of the front and back film layers and the thickness of the intermediate film layer may be appropriately determined according to the purpose of use, while maintaining excellent shrinkage characteristics from a low temperature range to a high temperature range and reducing the specific gravity as much as possible. From the viewpoint, it is preferable that the front film layer / intermediate film layer / back film layer = 1
/ 3 to 20 / 0.5 to 2, more preferably front film layer / intermediate film layer / back film layer = 1/5 to 12 /
0.7 to 1.5, and more preferably, front film layer / intermediate film layer / back film layer = 1/5 to 12/1. The total film thickness may be appropriately determined according to the purpose of use. Usually, the thickness is generally 10 to 100 μm.

The film of the present invention can be produced by a known method. The form of the film is flat,
Any of a tube shape may be used, but a planar shape is more preferable in terms of productivity (a number of products can be taken in the width direction of the raw film) and printing on the inner surface. As a manufacturing method in the case of a planar shape, for example, a resin is melted using a plurality of extruders, co-extruded from a T-die, cooled and solidified by a chilled roll, roll-stretched in a longitudinal direction, and tenter-stretched in a lateral direction. , Annealed, cooled, and wound (with corona discharge treatment on the surface if printing is performed) by a winder to obtain a film. Further, a method in which a film manufactured by the tubular method is cut open to form a planar shape can also be applied.

The stretching ratio is 2 to 10 times in the vertical direction and 2 in the horizontal direction in applications for contracting in two directions, such as for overlapping.
10 to 10 times, preferably 3 to 6 times in the vertical direction, 3 to 6 times in the horizontal direction
About six times is desirable. On the other hand, in an application mainly shrinking in one direction, such as for shrink labels, the direction corresponding to the main shrinking direction is 2 to 10 times, preferably 4 to 8 times, and the direction orthogonal thereto is 1 to 2 times (1x). It is desirable to select a magnification ratio in the range of substantially uniaxial stretching, preferably 1.1 to 1.5 times, that is, not stretching. Since the film obtained at the normal biaxial stretching magnification also has a large heat shrinkage in the direction orthogonal to the main shrinkage direction, for example, when used as a shrink label, when the film is mounted on a container, the film is also in the height direction of the container. A so-called vertical shrinkage phenomenon of thermal contraction occurs, which is not preferable.

A method for producing a shrinkable label from the film thus obtained is described below. The corona discharge treated surface of the film manufactured at a magnification ratio substantially in the category of uniaxial stretching is printed by an appropriate method such as gravure printing. At this time, it is general that the end of the film serving as a seal margin is a printed pattern that becomes a non-printed portion.

[0030] In order to obtain a tubular label from the printed planar heat-shrinkable film thus obtained, center sealing with an organic solvent is performed. This center sealing process will be described with reference to FIG. FIG. 1 is a simplified diagram showing a typical center seal processing method, wherein 1 is a flat film folded at both ends in an envelope shape, 2 is a tubular film formed by center sealing, 3 is a center sealing portion, Is a seal fee, 5 is a nozzle for applying an organic solvent,
Reference numeral 6 denotes a nip roll. The film travels in the direction of the arrow in FIG. 1, an organic solvent is applied to the seal margin 4 from the nozzle 5, and is pressed by the nip roll 6 to produce a tubular film. Next, this is cut to an appropriate length to obtain a shrink label. The speed of the center seal is usually 80 to 170 m / min, preferably 120 m / min.
１５０150 m / min.

The organic solvent used is not particularly limited as long as it dissolves or swells the front and back film layers of the film. For example, C5-C10 aliphatic hydrocarbons such as tetrahydrofuran, n-pentane and n-hexane can be exemplified. For the resin composition of the present invention, from the viewpoint of stable productivity, it is more preferable to use tetrahydrofuran as the organic solvent.

If the specific gravity of the shrink label is less than 1 (specific gravity including printing in the case of a printed product), it is more preferable for PET bottles in terms of recycling. The container to which the shrinkable label of the present invention is attached is most preferably a PET bottle as described above, but is not limited thereto, and may be another plastic container or a glass container.

[0033]

Next, an embodiment will be described. The methods for measuring and evaluating the physical properties used in the present invention are as follows.

The lubricity of the corona discharge treated surface of the film is measured by the following method. That is, HEI manufactured by Shinto Kagaku Co., Ltd.
DON 14DR SURFACE PROPERTY
Ten samples were measured using TESTER in accordance with ASTM D 1894, and the average value was defined as a static friction coefficient μs and a dynamic friction coefficient μd.

The waist (hardness) of the heat-shrinkable film is measured by
LOOP STIFFNE manufactured by Toyo Seiki Seisaku-sho, Ltd.
It was measured using SS TESTER.

The measurement of the heat shrinkage in hot water and boiling water at 70 ° C. is performed by the following method. That is, 10 samples of 100 mm × 100 mm in length × width are cut out from the heat-shrinkable film. Then, one of the samples is immersed in a hot water bath at 70 ° C. (or boiling water) for 10 seconds, and immediately cooled with cold water, and then the length L (mm) in the vertical or horizontal direction is measured. Then, 100-L is calculated. The same was repeated for the remaining nine samples, and the average value of the ten samples was calculated as 7
The heat shrinkage in the vertical or horizontal direction at 0 ° C. (or boiling water) was taken.

The shrinkage stress is measured by the following method. That is, the main shrinkage direction of the film × the direction orthogonal thereto = 15
Cut out the sample to 0mm length x 10mm width, and the interval is 1
A mark is drawn in the main shrinkage direction of the film so as to be 00 mm, and a sample is taken at a distance between chucks of 100 mm by HEIDON 17 PEELING TE manufactured by Shinto Kagaku Co., Ltd.
After setting to STER, it is immersed in warm water of 80 ° C. for 30 seconds, and the maximum stress during this is measured. Similarly, the maximum stress was measured for a total of 10 samples, and the average value was defined as the shrinkage stress.

Evaluation of the whitening was performed by touching the surface film layer surface of the shrinkable label with a hand, thermally shrinking, and visually evaluating the shrinkable label.

(Example 1) 100 parts by weight of a random copolymer of ethylene and a cyclic olefin (Apel 8008T manufactured by Mitsui Chemicals, Inc.) to be the front and back film layers, and a linear low-density polyethylene (NUC manufactured by Nippon Unicar Co., Ltd.)
G5225) A propylene-ethylene random copolymer containing 80 parts by weight of a hydrogenated terpene resin (Clearon P135 manufactured by Yashara Chemical Co., Ltd.) and 20 parts by weight of a hydrocarbon resin to be an intermediate film layer Grand Polymer F237
V) A blend polymer composition of 100 parts by weight, 12 parts by weight of a linear low-density polyethylene (NUCG5225 manufactured by Nippon Unicar Co., Ltd.) and 12 parts by weight of ethylene-propylene rubber (PER T310E manufactured by Tokuyama Corporation) It is put into a separate extruder, co-extruded from a co-extrusion T-die at 230 ° C., taken up on a chilled roll through warm water at 35 ° C., solidified by cooling, and then rolled at 83 ° C. in a 1.2-fold lengthwise direction. Stretching, then 125 ° C
After preheating at 95 ° C for 8 seconds, the tenter is stretched 6 times in the horizontal direction at 95 ° C, and annealed at 80 ° C for 8 seconds while relaxing 5% in the width direction in the tenter. Min / m ² for corona discharge treatment,
A planar multilayer heat shrinkable film was obtained. The thickness of this film was 5 μm for both front and back film layers, 40 μm for the intermediate film layer, and a total of 50 μm. Table 1 shows the waist of the film, the thermal shrinkage in the lateral direction, the shrinkage stress, and the coefficient of static friction μs and the coefficient of dynamic friction μd between the back film layers of the film.

(Example 2) A five-color printing of a predetermined pattern was performed on the backside film layer surface of this film by a gravure printing machine.
The printed pattern used was a three-cutter (split into three parts) in the width direction of the film, and each end was used as a non-printed part. Next, three slits (three divisions) were made with a slitter. Then, using a center seal device having a mechanism as shown in FIG. 1, using tetrahydrofuran as an organic solvent, the center was sealed at a processing speed of 130 m / min to produce a cylindrical heat-shrinkable label (raw material). The folding diameter is 1
08.5 mm and the seal allowance was 4 mm wide. Then
This tube was cut into a length of 80 mm to form a cylindrical heat-shrinkable label, a PET bottle was inserted, and the surface film layer surface was touched by hand. Then, a wet heat shrink tunnel (length 3 m,
The label was heat-shrinked at 80 ° C. for 5 seconds using a vapor pressure of 0.3 kg / cm ² ), and the label was heat-shrinked by using the heat shrinkage to bring the label into close contact with the PET bottle. The label was tightly adhered to the bottle, was not whitened, and was beautiful without wrinkles or avatars.

Comparative Example 1 A multilayer heat-shrinkable film was obtained in the same manner as in Example 1, except that no linear low-density polyethylene was blended in the front and back film layers. Table 1 shows the stiffness, heat shrinkage, shrinkage stress, and static friction coefficient μs and kinetic friction coefficient μd of the back film layers of the film. Next, a cylindrical heat-shrinkable label was obtained from this film in the same manner as in Example 2, and when attached, shrunk, and adhered to a PET bottle, the place touched by hand was whitened, resulting in no commercial value. Also, some wrinkles were observed on the inner surface of the seal portion (the surface in contact with the PET bottle). This is considered to be because the lubrication of the film was deteriorated by the corona discharge treatment.

Comparative Example 2 A single-layer heat-shrinkable film having a thickness of 50 μm was produced in the same manner as in Example 1 except that a single-layer film was formed using the same resin composition as the front and back film layers used in Example 1. I got Table 1 shows the stiffness, heat shrinkage, shrinkage stress, and static friction coefficient μs and dynamic friction coefficient μd of the back surfaces of the film. Next, a cylindrical heat-shrinkable label was obtained from this film in the same manner as in Example 2, and when attached, shrunk, and adhered to a PET bottle, an avatar was generated on the film and the appearance was poor. This is shown in Table 1.
As can be seen from the shrinkage rate of the cylindrical heat-shrinkable label at 70 ° C. and boiling water, it is considered that the heat-shrinkage of the label occurred rapidly.

[0043]

[Table 1]

[0044]

Since the present invention has the above-described configuration, the following effects can be obtained.

Even if the surface of the shrink film is touched by hand, it does not whiten after shrinking. Further, even if a corona discharge treatment is performed to improve the adhesion to the printing ink, it is possible to maintain a degree of lubricity that causes no practical problem.

In addition, it has a stiffness, has little natural shrinkage near room temperature, has dimensional stability, has good shrinkage characteristics from a relatively low temperature range to a high temperature range, and has an appropriate shrinkage stress. Further, when processing into a label, the center can be sealed with an organic solvent, so that a simple and beautiful label can be obtained.

When the label is lightweight and has a specific gravity of less than 1, it can be separated by a specific gravity separator during recycling.

Furthermore, since it has a gentle shrinkage characteristic with respect to temperature and has an appropriate shrinkage stress, it is possible to provide a beautiful container in which a label is tightly mounted and which is free from wrinkles, avatars and the like.

[Brief description of the drawings]

FIG. 1 is a simplified diagram showing a center sealing method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flat film 2 Tubular film 3 Center seal part 4 Seal margin 5 Nozzle for applying organic solvent 6 Nip roll

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akihiro Inukai 580-32 Nagaura, Sodegaura-shi, Chiba F-term in Grand Polymer Co., Ltd. (reference) AL05B AL05C AN02 BA03 BA04 BA05 BA10A BA10C BA15 DA01 EH20 EJ55 GB16 GB23 GB90 HB31 JA03 JK16 JL03 JL04 YY00A YY00C

Claims (3)

[Claims] 1. A front and back film layer mainly comprising a resin composition obtained by blending 60 to 150 parts by weight of a linear low-density polyethylene with 100 parts by weight of a cyclic olefin resin, and a propylene-α-olefin random copolymer or A multilayer heat-shrinkable film having at least three or more layers having an intermediate film layer formed of a resin composition containing the copolymer as a main component. 2. A cylindrical shrinkable label made from the multilayer heat shrinkable film of claim 1. 3. A label mounting container on which the cylindrical shrinkable label according to claim 2 is mounted.