JP2001162725A - Heat-shrinkable polyolefinic film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-shrinkable polyolefinic film advantageous in productivity because of its capability of being formed into a cylindrical label by using a solvent seal, capable of being separated from PET based on a difference in specific gravity because of its specific gravity of below 1 and advantageous to recycle. SOLUTION: In a heat-shrinkable polyolefinic film consisting of at least three layers, both surface layers are constituted of a cyclic olefinic copolymer resin with a glass transition temperature of 50-75 deg.C and an intermediate layer is constituted of a resin composition based on a polypropylene type copolymer resin and the total thickness of both surface layers is 10-40% with respect to the total thickness of the film and the thickness of the intermediate layer is 60-90%. The heat shrinkage factor of the film measured when the film is immersed in a glycerine bath at 100 deg.C for 30 sec is 40% or more in a main shrink direction and 15% or less in the direction crossing the main shrink direction at a right angle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-shrinkable polyolefin film in which a tubular label can be easily produced by joining with a solvent seal, and a P-type film provided with the tubular label.
Regarding ET bottles.

[0002]

2. Description of the Related Art PE having a heat-shrinkable cylindrical label attached thereto.
In recent years, T bottles have been actively recycled. As a recycling method, generally, a method of pulverizing a collected PET bottle to obtain a recycled PET flake or a recycled PET pellet is employed.

[0003] The recovered PET bottle is usually several mm in size.
The crushed product of the label is removed by wind power from the crushed product having a size of 〜１０10 mm square. Furthermore, by removing the aluminum cap pulverized body from the PET bottle pulverized body,
Recycled PET flakes or pellets are obtained.

[0004] Since the above-mentioned method of sorting by wind power is not perfect, if the label has a specific gravity of less than 1, water is used, and the sorting method by the difference in specific gravity is extremely simple and the processing capacity is large. As a tubular label made of a heat-shrinkable film, a label having a specific gravity of less than 1 is demanded.

As heat shrinkable films having a specific gravity of less than 1, various films made of heat shrinkable olefin resin films have been developed.

[0006]

Conventionally, various heat-shrinkable films such as polyvinyl chloride, polystyrene, polyester, and polyolefin have been developed as heat-shrinkable films to be processed into cylindrical labels. ing.
Among the above, the non-polyolefin film is processed by applying a solvent to the end of one of the films in a tubular shape so that the width direction of the printed film is the circumferential direction, and then processed in a predetermined manner. Cut into lengths to obtain labels to be attached to bottles.

On the other hand, a polyolefin-based heat-shrinkable film has good solvent resistance and cannot be bonded in a cylindrical shape by the above-mentioned solvent seal. For this reason, usually, after corona treatment, a method of processing by sticking in a cylindrical shape using an adhesive such as urethane is used, so that the processing speed is slow, and the curing is not performed for one to several days. There is a problem that can not be used.

An object of the present invention is to provide a heat-shrinkable polyolefin film, which is advantageous in terms of productivity because it can be formed into a cylindrical label by laminating the film with a solvent seal, and has a specific gravity of the film. Is less than 1, it is possible to provide a heat-shrinkable film that can be separated from PET at a specific gravity and is advantageous for recycling.

[0009]

SUMMARY OF THE INVENTION The present invention provides at least 3
In the heat-shrinkable polyolefin film composed of layers, both surface layers are composed of a cyclic olefin copolymer resin having a glass transition temperature of 50 ° C to 75 ° C, and the intermediate layer is composed of a fat composition mainly composed of a polypropylene copolymer resin. Has been
The total thickness of both surface layers is 10 to 40%, and the thickness of the intermediate layer is 60 to 90% of the total thickness of the film, and the film is immersed in a glycerin bath at 100 ° C. for 30 seconds. The heat shrinkage in the main shrinkage direction is 40% or more, and the heat shrinkage in the direction orthogonal to the main shrinkage direction is 15% or less.

In the present invention, the specific gravity of the heat-shrinkable polyolefin film is preferably 0.97 or less. When the specific gravity is equal to or less than the specific gravity, the specific gravity of the printed tubular label can be set to 1 or less, and a specific gravity of 0.95 or less is more preferable.

Further, in the present invention, the polypropylene copolymer resin of the intermediate layer contains ethylene in an amount of 0.2 to 10 mol%.
Characterized in that the ethylene-propylene random copolymer and / or butene is 0.2 to 30 mol% butene-propylene random copolymer.

In the present invention, the resin composition mainly composed of a polypropylene copolymer resin in the intermediate layer comprises a cyclic olefin copolymer tree having a glass transition temperature of 50 ° C. to 75 ° C.
It is characterized by containing an amount of 0% by weight or less.

Further, according to the present invention, a resin composition containing a polypropylene copolymer resin as a main component of the intermediate layer is mixed with a glass transition temperature by mixing a recycled product of the above-mentioned heat-shrinkable polyolefin film into the intermediate layer. Is 50 ℃ ～ 7
It is characterized by containing a cyclic olefin copolymer tree at 5 ° C.

Further, according to the present invention, the cyclic olefin copolymer having a glass transition temperature of 50 ° C. to 75 ° C., which forms both surface layers, is a random copolymer of α-olefin and cyclic olefin. Other cyclic olefin-based copolymers and other olefin-based resins can be blended as long as the properties and the heat shrinkage properties of the film are not impaired.

Further, the present invention is a PET bottle provided with a tubular label comprising the above-mentioned heat-shrinkable polyolefin film.

[0016]

Embodiments of the present invention will be described in detail below.

The resin composition mainly comprising a polypropylene copolymer resin constituting the intermediate layer according to the present invention comprises an ethylene-propylene random copolymer containing 0.2 to 10 mol% of ethylene and / or butene containing 0 to 10 mol%. .2 to 30 mol% of a butene-propylene random copolymer as a main component, and other olefin resin or petroleum resin.
In addition, if necessary, a cyclic olefin copolymer tree having a glass transition temperature of 75 ° C. or lower may be contained by blending the intermediate layer in order to recycle a defective product of a heat-shrinkable polyolefin film at a factory. It can be used, but its amount is not more than 30% by weight. If the amount exceeds this amount, the transparency is greatly reduced, which is not preferable.

The petroleum resin blended in the intermediate layer comprises an aliphatic hydrocarbon, an alicyclic hydrocarbon, a hydrogenated hydrocarbon and the like, and is blended in a range of 1 to 40% by weight. If this amount is less than 1% by weight, the shrinkage properties deteriorate, and
If it exceeds 40% by weight, the film strength is undesirably reduced.

Other olefin resins to be blended in the intermediate layer include ethylene-butene-propylene copolymer resin, polybutene resin, ionomer resin, LL
DPE resin, LDPE resin, EVA resin and the like. These resins can be blended in an amount of 10% by weight or less. Exceeding this amount is not preferred because the strength and rigidity are greatly reduced.

The cyclic olefin copolymer resin constituting both surface layers of the present invention has a glass transition temperature of 50 ° C. to 75 ° C.
Preferably, it is in the range of 55 ° C to 73 ° C. Examples of the cyclic olefin copolymer resin include a random copolymer resin of an α-olefin having 2 to 20 carbon atoms and a cyclic olefin, or a graft modified product thereof. If the above glass transition temperature exceeds 75 ° C., the stretching temperature becomes too high, and the heat shrinkage of the heat-shrinkable polyolefin film is lowered. Not preferred. This cyclic olefin-based copolymer resin is, specifically, "Zeonor" manufactured by Zeon Corporation.
(Trade name), “APEL” (trade name) manufactured by Mitsui Chemicals, Inc., and “Topas” (trade name) manufactured by Hoechst Co., Ltd., and those having the above glass transition temperature can be used.

Solvents used for processing the heat-shrinkable polyolefin-based film of the present invention into a tubular shape by sealing with a solvent include aliphatic hydrocarbon-based solvents such as n-hexane and n-pentane, and oils such as cyclohexane. Examples thereof include a cyclic hydrocarbon solvent, an aromatic hydrocarbon solvent such as toluene, xylene, and benzene.
An n-hexane-based mixed solvent is preferably used.

Next, a method for producing a heat-shrinkable polyolefin film will be described. The film is manufactured by a known co-extrusion technique or stretching technique. For example, a flat sheet is co-extruded from a T-die so that both surface layers are a cyclic olefin copolymer resin and the intermediate layer is a three-layer composed of a resin composition containing a polypropylene copolymer resin as a main component, Cool, take off, stretch by 1.0 to 2.0 times in the machine direction, stretch by 10 to 10 times in the transverse direction, anneal while relaxing in the width direction by 0 to 12%, and then heat by winding. A shrinkable polyolefin film is obtained. Stretching may be performed by a known simultaneous biaxial stretching method.
Alternatively, a tubular sheet may be co-extruded from a round die and stretched in a tubular shape, or the sheet may be cut open to form a flat shape and stretched as described above.

[0023]

EXAMPLES Next, typical examples of the present invention will be described.

The method of measuring physical properties used in the present invention is as follows.

[Measurement of Heat Shrinkage Ratio of Heat Shrinkable Olefin Film] The length × width of the manufactured film is 100 mm ×
Cut a sample into 100 mm square. Then, this sample was
After being immersed in a glycerin bath at 00 ° C. for 30 seconds and immediately cooled with cold water, the length L (mm) in the vertical and horizontal directions is measured. Then, (100−L) / 100 is calculated, and is set as the heat shrinkage in the vertical and horizontal directions.

[Measurement of Solvent Seal Strength of Heat Shrinkable Olefin Film] At a position 10 mm from both ends in the horizontal direction of the produced film, cyclohexane 10% by weight, n-
A cylindrical label was manufactured by solvent sealing using a mixed solvent consisting of 90% by weight of hexane. The seal part of the cylindrical label was cut out to a width of 5 mm in a direction perpendicular to the circumference and set on an “Autograph type tensile tester” manufactured by Shimadzu Corporation.
The seal strength was measured at a tensile speed of 200 mm / min in a peel test. The evaluation criteria are as follows. : 50 g / 5 mm or more △: 20 g / 5 mm or more, less than 50 g / 5 mm ×: less than 20 g / 5 mm

Example 1 As a resin composition mainly composed of a polypropylene copolymer resin constituting an intermediate layer, 30% by weight of an ethylene-propylene random copolymer containing 4.6 mol% of ethylene and 22.7% of butene were used. Mol% butene-propylene random copolymer 30% by weight, polybutene resin (Takuma M-248)
1, 4% by weight of Mitsui Chemicals, Inc., petroleum resin (Alcon P-
140, manufactured by Arakawa Chemical Co., Ltd.), and 20% by weight of a cyclic olefin copolymer resin (Zeonor L-7, Tg: 70 ° C., manufactured by Nippon Zeon). L-7), and put into separate extruders, extruded from a T-die at 230 ° C. to form three layers, cooled and solidified by a cooling roll at 40 ° C. The film was stretched twice and then annealed at 75 ° C. for 5 seconds while relaxing 8% in the width direction in the tenter to obtain a heat-shrinkable olefin film having a thickness of 50 μm (the thickness of each layer was 5 μm / 40 μm). / 5μ
m). Table 1 shows the physical properties of the film.

Example 2 As a resin composition mainly composed of a polypropylene copolymer resin constituting an intermediate layer, 70% by weight of an ethylene-propylene random copolymer containing 4.6 mol% of ethylene, a petroleum resin (Alcon P -140, Arakawa Chemical Co., Ltd.) 20% by weight, cyclic olefin copolymer resin (Zeonor L-7, T
g: 70 ° C, manufactured by Zeon Corporation) and 10% by weight of the above-mentioned cyclic olefin copolymer resin (ZEONOR L-
7), and put into separate extruders, extruded from a T-die at 230 ° C. to form three layers, solidified by cooling with a cooling roll at 0 ° C., and then ten-fold tenter stretching in the transverse direction at 80 ° C. Subsequently, the film was annealed at 75 ° C. for 5 seconds while relaxing 8% in the width direction in the tenter to obtain a heat-shrinkable olefin film having a thickness of 50 μm (the thickness of each layer was 5 μm).
/ 40 μm / 5 μm). Table 1 shows the physical properties of the film.

Example 3 As a resin composition mainly composed of a polypropylene-based copolymer resin constituting the intermediate layer, 24% by weight of an ethylene-propylene random copolymer containing 4.6 mol% of ethylene and 22.7% of butene were used. Mol% butene-propylene random copolymer 24% by weight, polybutene resin (Tuffmer M-248)
1, 2% by weight of Mitsui Chemicals, petroleum resin (Alcon P-
140, manufactured by Arakawa Chemical Co., Ltd.) and 10% by weight of the heat-shrinkable olefin film produced in Example 1 and 40% by weight, and a cyclic olefin copolymer resin (Zeonor L-7) was used as both surface layers. , Each extruded into different extruders and extruded from a T-die at 230 ° C. so as to form three layers.
After being cooled and solidified by a cooling roll at 0 ° C., the tenter is stretched 7 times in the transverse direction at 80 ° C., and subsequently annealed at 75 ° C. × 5 seconds in the same tenter while relaxing 8% in the width direction, and has a thickness of 50 μm. Was obtained (the thickness of each layer was 5 μm / 40 μm / 5 μm). Table 1 shows the physical properties of the film.

COMPARATIVE EXAMPLE 1 In the heat-shrinkable olefin film produced in Example 1, both surface layers were made of ethylene-propylene random copolymer having 4.6 mol% of ethylene.
A heat-shrinkable olefin-based film having a thickness of 50 μm was obtained in the same manner as in Example 1 except that the film was stretched by tenter and annealed at 55 ° C. × 5 seconds (the thickness of each layer was 5 μm / 40 μm).
/ 5 μm). Table 1 shows the physical properties of the film.

[0031]

[Table 1]

[0032]

The heat-shrinkable olefin film of the present invention can be processed into a cylindrical label by solvent sealing.
Processing is easy and processing speed can be increased. In addition, since the whole is made of olefin resin, defective products can be recycled to the intermediate layer at the film manufacturing site, and the specific gravity of the printed cylindrical label can be made smaller than 1, so that the specific gravity separation with PET can be performed with water. Since it is possible, it is extremely useful as a heat-shrinkable cylindrical label for PET bottles.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F100 AK02 AK03A AK03B AK03C AK03J AK07C AK07J AK62C AK67C AL01A AL01B AL01C BA03 BA06 BA10A BA10B BA15 DA01 GB90 JA03 JA05A JA05B JA05C JA20A JA20B JA20Y00Y

Claims (7)

[Claims] 1. A heat-shrinkable polyolefin film comprising at least three layers, wherein both surface layers are mainly composed of a cyclic olefin copolymer resin having a glass transition temperature of 50 ° C. to 75 ° C., and the intermediate layer is mainly composed of a polypropylene copolymer resin. And the total thickness of both surface layers is 10 to 40%, and the thickness of the intermediate layer is 60 to 90% of the total thickness of the film. ° C
Wherein the heat shrinkage in the main shrinkage direction when immersed in the glycerin bath for 30 seconds is 40% or more, and the heat shrinkage in the direction orthogonal to the main shrinkage direction is 15% or less. . 2. The heat-shrinkable polyolefin film according to claim 1, wherein the specific gravity of the heat-shrinkable polyolefin film is 0.97 or less. 3. The polypropylene copolymer resin of the intermediate layer contains an ethylene-propylene random copolymer containing 0.2 to 10 mol% of ethylene and / or a butene containing 0.2 to 0.2 mol% of butene.
The heat-shrinkable polyolefin film according to claim 1, which is a butene-propylene random copolymer of up to 30 mol%. 4. The resin composition mainly comprising a polypropylene copolymer resin of the intermediate layer has a glass transition temperature of 50 ° C. or more.
The heat-shrinkable polyolefin-based film according to claim 1, wherein the content of the cyclic olefin-based copolymer tree at 75 ° C is 30% by weight or less. 5. A polypropylene-based olefin resin composition for the intermediate layer having a glass transition temperature of 50 ° C. to 75 ° C. by blending a recycled product of the heat-shrinkable polyolefin film in the intermediate layer. The heat-shrinkable polyolefin film according to claim 4, further comprising a polymerized tree. 6. The cyclic olefin-based copolymer tree having a glass transition temperature of 50 ° C. to 75 ° C. is a random copolymer of α-olefin and cyclic olefin. 2. The heat-shrinkable polyolefin film according to item 1. 7. A PET bottle equipped with a tubular label comprising the heat-shrinkable polyolefin film according to claim 1.