WO1995012490A1

WO1995012490A1 - Heat-shrinkable laminated polyethylene film

Info

Publication number: WO1995012490A1
Application number: PCT/JP1993/001588
Authority: WO
Inventors: Syuuichi Morita; Shigeyoshi Koyabu; Tamio Moriyama; Masaaki Tateiwa
Original assignee: Kohjin Co., Ltd.
Priority date: 1993-11-02
Filing date: 1993-11-02
Publication date: 1995-05-11
Also published as: CA2118002A1; CA2118002C

Abstract

A heat-shrinkable laminated polyethylene film which is excellent in the adaptability for wrapping machines. The film is composed of an intermediate layer comprising a composition based on a linear low-density polyethylene (A) having a density of 0.910-0.930 g/cm3, a melt index of 0.1-0.8 g/10 min, a total heat quantity of fusion of 135 mJ/mg or above, and the endothermic area above the melting point accounting for at least 12 % of the total endothermic area, and the innermost and outermost layers each comprising a composition based on a linear low-density polyethylene (B) having a density of 0.910-0.930 g/cm3, a melt index of 0.8-5.0 g/10 min, a total heat quantity of fusion of 135-160 mJ/mg, and the endothermic area above the melting point accounting for at least 12 % of the total endothermic area.

Description

Technical Description Polyethylene-based heat-shrinkable laminated film

The present invention relates to a polyethylene-based heat-shrinkable laminated film, and more particularly, to a heat-shrinkable laminated film made of a specific ethylene-based copolymer and having excellent suitability for a packaging machine. Regarding the film.

Background art

Conventionally, as heat shrinkable films, stretched films such as polyvinyl chloride, polypropylene, and polyethylene have been known. Among them, polyethylene-based heat-shrinkable films have been used because of their heat-sealing properties and low cost. Low-density copolymer (hereinafter simply abbreviated as linear low-density polyethylene) of polystyrene and α-olefin refrigeration. Lum is noted for its excellent impact resistance and heat seal strength, and is expected to be used in many fields.

The present inventors have previously proposed a heat-shrinkable film mainly comprising a specific ethylene-α-olefin copolymer (Japanese Patent Application Laid-Open No. 62-201). No. 229 Publication). By implementing the proposed method, the thickness of the film is small and the low-temperature shrinkage of the film is better than that of the film obtained by inflation. The use of automatic packaging machines (pillow wrapping machines, half-fold automatic wrapping machines, etc.) as packaging materials in recent years has led to the increase in packaging speed of packaging machines. Since the speed is significantly increased, there is a problem in that a heat seal defect (partially not sealed), which has not occurred in the past, may occur. When wrapping with an automatic wrapping machine, heat seals are generally heat-sealed by heat heat. When the film is separated or a large tension is applied to the film (when the packaged material is bulky, etc.), Fingers may not be beautifully pressed into a stringing shape, pinholes may be formed on the seal, and in extreme cases they may not be sealed at all. are doing.

Further, when the melted resin adheres to the blade edge of the heat knife or the heat knife tray, the same seal failure as described above occurs. Disclosure of the invention

The inventors of the present invention have conducted further detailed studies in order to eliminate the above-described seal failure, and as a result, have confirmed the following.

In other words, when the packaging speed becomes faster, the time required for shrinkage in the shrinking tunnel becomes shorter, and solidification of the melted resin does not progress within that short time. In addition, part of the blown resin is pulled apart, causing pinholes or, in extreme cases, completely separating the seal.

Also, if the film has low stiffness (small tensile elasticity), it becomes easier for the film to enter during film running, so it is necessary to use a fusing seal at the part where the film is to be sealed. The number of folded parts of the film will increase, and the occurrence of binholes will increase.

In addition, when the film is poor in slipperiness and the running property in the packaging machine is insufficient, or when the packaged material is bulky, a greater tension is applied to the fusing seal part and fusing occurs. Before the resin solidifies, part of the seal is torn off, increasing the occurrence of pinholes.

Furthermore, if the viscosity of the fusing resin is low, the fusing resin tends to adhere to the blade edge of the heat knife or the heat knife base, and pinholes are generated in the seal portion. The film must not be cut or, in extreme cases, not completely sealed.

In order to solve the above-mentioned problems and to provide a heat-shrinkable film having good suitability for a packaging machine, the present inventors have made intensive studies on the laminated structure of the film and various kinds of raw material resins. The layer has a low melt index, high total heat of fusion, and a high endothermic area ratio above the melting point to increase the cooling and solidification rate during the fusing seal. Using a In order to maintain the transparency of the inner and outer layers, a resin with a higher melt index than that of the intermediate layer and having the same characteristics as the intermediate layer is used. It has been found that a heat-shrinkable film having good suitability for a packaging machine can be obtained, and the present invention has been achieved.

That is, according to the present invention, the intermediate layer has a density of 0.910 to 0.930 g / cm ³ and a melt index of 0.1 to 0.88TZ 10. In the melting curve by DSC, after holding for 30 minutes at 190, the temperature was lowered to 20'C in 10 minutes, and then the temperature was raised. Total heat of fusion in the melting curve obtained when the temperature is increased in 10 minutes at a rate of 10 min. Is not less than 135 mJ Zmg and an endotherm not less than the main peak temperature (melting point). At least one layer composed of a composition mainly composed of linear low-density polyethylene (A) having an area of 12% or more of the total endothermic area, and at least one layer of melt-in The index is 0.8 to 5.Og / 10 min, and the total heat of fusion in the melting curve is in the range of 135 to 160 mJ / mgr; Linear low-density poles whose endothermic area above the main peak temperature is 12% or more of the total endothermic area A laminated film containing, as an innermost layer and an outermost layer, a layer composed of a composition mainly composed of styrene (B), wherein the thickness of the intermediate layer is 60% with respect to all the layers. more der is, tensile modulus 3 0 0 0 kgcm ² than on, 9 0 ° put that area shrinkage C is you characterized and this Ru der 2 0% or biaxially stretched packaging machine It relates to a polyethylene-based heat-shrinkable laminated film with excellent suitability.

At least one layer of the linear low-density polyethylene (A) used as a main component of the intermediate layer in the present invention has a density of 0.910 to 0.930 s Z cm ³ , Melt index 0 1 to 0 8 S / 10 A material with a characteristic value of 10 minutes is used, and more preferably, the density is 0.9 to 15 to 0.9. 25 g- / cm ³ ^ melt index 0.2 to 0.7 sr / 10 min. Density 0. 9 1 0 g / cm ³ non Mitsurude is rather to Do rather preferable because tensile modulus that Do rather low, the density is exceeds the 0. 9 ³ 0 gZ cm 3 low temperature shrinkability is insufficient Not good because of it.

If the melt index is less than 0.1 lgr / 10 minutes, melt extrusion It is not preferable because the motor load at the time increases and the workability deteriorates, and if it exceeds 0.8 s / 10 minutes, it is preferable because the fusing sealability deteriorates. Not good.

The linear low-density polyethylene (A) has a total heat of fusion of 135 mJ / m sr or more in the melting curve in the DSC measurement, and a main peak temperature. The above endothermic area must be at least 12% of the total endothermic area. If the condition is not satisfied, the cooling and solidification rate of the blown resin is slow, and good blown sealability cannot be obtained.

The thickness of the intermediate layer with respect to all layers must be 60% or more. When the thickness of the intermediate layer is less than 60%, excellent fusing sealability cannot be exhibited.

In addition, the linear low-density polyethylene (B) used as a main component in the innermost layer and the outermost layer has a melt index of 0.8 to 5. 0 g Z 10 minutes, the total heat of fusion in the melting curve is in the range of 135 to 160 mJ / mg, and the endothermic area above the main peak temperature is Those having 12% or more of the total endothermic area are used.

When the melt index is less than 0.8 gr 10 min, the transparency is lowered due to the roughening of the film surface, which is not preferable. If it exceeds S / 10 minutes, the heat seal strength is reduced and the drawability is adversely affected, which is not preferable. Further, if the total heat of fusion is less than 135 mJZmg, good fusing sealability is not obtained, and if it exceeds 160 mJZmg, the transparency is unfavorably reduced.

The above linear low-density polyethylene (A) and (B) are a linear copolymer of ethylene and an ethylene olefin, and are copolymerized with ethylene. The α-olefin resin to be polymerized is not particularly limited. For example, butene-11, pentene-11, hexene-11, heptene-11, octene1-1,4-methan with 4 to 12 carbon atoms Tilpentene-11, decene-11, pendecene-11, dodecene-11, etc., among which α-branched olefins having 4 to 8 carbon atoms are more preferable. Used for The linear copolymers (Α) and (Β) of these ethylenes and α-olefins are so-called cheeks. It can be easily obtained by a low-to-medium pressure method using a Lana-tuna type catalyst, and these production methods are described in Japanese Patent Publication No. 50-32270 and Japanese Patent Application Laid-Open No. 49-135. Japanese Patent Publication No. 3445, Japanese Patent Application Laid-Open No. 55-78004, Japanese Patent Application Laid-Open No. 55-8684, Japanese Patent Application Laid-Open No. 54-154488, etc. It can be based on the disclosed technology.

The resin composition used in each of the above layers may be used alone or in combination of two or more. Further, the resin composition used in the high-pressure polystyrene may be used as long as the object of the present invention is not hindered. Polyolefin resin such as ethylene-vinyl acetate copolymer, ionomer, ethylene-propylene copolymer, etc. Can be done.

In addition, the laminated film of the present invention includes the above-mentioned linear low-density polyethylene resin (A) in a range satisfying the above-described thickness conditions of each layer in addition to the intermediate layer, the innermost layer, and the outermost layer. ) And (B) may contain one or two or more intermediate layers made of a polyolefin resin. As the polyolefin resin used for such an intermediate layer, a linear low-density polyethylene resin (A) and a linear resin other than (B) are used. Polyolefin resins such as high-density polyethylene resins, high-pressure polyethylene resins, and ethylene-propylene copolymers, and the like. One type or two or more types can be appropriately selected and used as long as they do not cause a problem.

In addition, if desired, additives such as lubricants, antiblocking agents, antistatic agents, and antifogging agents can be used as appropriate for the purpose of achieving their effective effects. This is especially effective for the innermost and outermost layers.

The production and stretching of the raw film for stretching used in the present invention can be performed by a known method.Hereinafter, a case of three-layer laminated tubular film forming and stretching will be described as an example. This will be specifically described.

First, the linear low-density polyethylene (A) of the above-mentioned ethylene and α-olefin is placed in the middle layer, and the linear low-density polyethylene of the ethylene and α-yearly refine is formed. The density polyethylene (Β) is melt-kneaded by three extruders so as to become inner and outer layers, and is co-extruded into a tube from a three-layer annular die, and is not stretched once. It is quenched and solidified to produce a tube-shaped unstretched film. The obtained tube-shaped unstretched film is supplied to, for example, a tuber stretching apparatus as shown in FIG. 1 to obtain a highly oriented temperature range, for example, below the melting point of the intermediate layer resin. A gas pressure is applied to the inside of the tube at 0'C, preferably below the melting point and at a temperature lower than 15 to cause simultaneous biaxial orientation by expansion and stretching. The stretching ratio does not have to be the same in both the vertical and horizontal directions.However, in order to obtain physical properties such as excellent strength and shrinkage, it should be at least 2 times in both directions, preferably 2.5 times or more. More preferably, it is stretched three times or more.

The film removed from the stretching device can be annealed as desired, and this elimination can suppress natural shrinkage during storage. I can do it. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a cross-sectional view for explaining a tuber biaxial stretching apparatus used in Examples.

FIG. 2 is a schematic diagram for explaining a load-deformation curve for calculating a tensile modulus in the example. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited to these Examples.

In addition, various measurements shown in this example were performed by the following methods.

1) Total heat of fusion

After weighing a sample of 8 to 1 O mg, enclose the sample in aluminum pan and use a differential scanning calorimeter (Seiko Denshi Co., Ltd., model DSC—100) with a nitrogen flow of 30 ml / min. Then, the temperature is raised from room temperature to 19 O'C in the atmosphere, kept at this temperature for 30 minutes, and then cooled to room temperature in 10 minutes and Z minutes. After this, using a melting curve that obtained in NoboriAtsushisoku degree 1 0 ^e C / min, was calculated Ri heat of fusion by the area of the endothermic peak.

2) Endothermic area ratio From the above melting curve, the ratio of the area above the main peak temperature (melting point) to the total endothermic area was indicated by%.

3) Thickness of each layer

The thickness of each layer of the laminate was measured by observing the cross section of the film with a microscope.

4) Hayes

The ratio of the scattered light transmittance to the parallel light transmittance was indicated by% using an integrating sphere light transmittance measuring device conforming to JIS-K6714.

5) Area shrinkage

A film cut into a square of 10 cm in both length and width was immersed in a glycerin bath at a predetermined temperature for 10 seconds, and calculated by the following equation.

Area shrinkage = 1 0 0-A X B

However, A and B indicate the vertical and horizontal lengths after immersion (unit: cm).

6) Tensile modulus

Take a test piece with a width of 15 mm and a length of 300 mm each in the MD (vertical direction) and TD (horizontal direction) from the film sample, and measure the thickness.

Next, the test specimens were gripped on an universal tensile tester manufactured by Orientec Co., Ltd. at an interval of 5 Omm, and the tensile speed was 40 mmZ, the recording paper speed was 50 Omm / min, and the full scale. Measured under the condition of 2 kg and calculated by the following formula.

P

S

Tensile modulus (kg / cm ²⁾ =

Δ L

L

However, P: Full scale strength (kg)

S: Cross-sectional area of the film (cm ² )

Λ L: distance from L 1 to L 2 in the load-deformation curve shown in Fig. 2 (mm) L: gap between test pieces 7) Fusing sealability

A half-fold film with a width of 40 O mm was supplied to a half-fold automatic packaging machine (model AT—500) manufactured by Kyowa Electric Co., Ltd., which was 23.5 cm long, 15.5 cm wide, and high. A 5.6 cm lunch box (200 g) is packed continuously at a speed of 25 pieces / min and 100 pieces are measured, and the non-defective rate is measured. If the non-defective rate in the seal temperature range of 100% is 100%, it is O, Δ is less than 100%, 80% or more is X, and X is less than 80%. Was.

The criteria for non-defective products were non-defective products that had no stringiness in the seal after shrink wrapping and had no pinholes of 1 mm or more.

The margin of spare packaging is set to 13% both vertically and horizontally.

Example 1

Linear low-density polyethylene which is a copolymer of ethylene having the properties shown in Table 1 and 41-methylpentene-11 as a comonomer Low-density polyethylene, which is a copolymer of ethylene and octen-11, also having the properties shown in Table 1 using resin as the intermediate layer The resin was melted and kneaded at 170 ° C to 240 ° C in three extruders (for the middle layer, the innermost layer, and the outermost layer) as the inner and outer layers, respectively, as shown in Table 1. The extrusion amount from each extruder was set assuming the thickness ratio, and co-extrusion was performed downward from a three-layer annular die maintained at 24 O'C.

The formed three-layer tube is used to slide the outer surface of the cylindrical cooling mandrel through which the cooling water circulates on the inside, while passing the water tank on the outside. After further cooling, the bow I was removed to obtain an unstretched film with a diameter of about 75 mm and a thickness of 320 m. The thickness of each layer was adjusted by adjusting the screw rotation speed and the take-up speed of the extruder. This tube-shaped unstretched film is guided to the tube biaxial stretching device shown in Fig. 1 and stretched four times in each of the vertical and horizontal directions at 95 to 105 to form a laminated biaxial film. A stretched film was obtained. Next, this stretched film is put into a chip-availing machine for 75. After being treated with hot air of C for 10 seconds, it was cooled to room temperature, folded and wound.

安定 Good stability during stretching, vertical movement of stretching point and swing of stretching tube No non-uniform stretching state such as necking was observed. The obtained stretched film had a thickness configuration as shown in Table 1, was excellent in transparency and low-temperature shrinkage, and had a high tensile modulus. In addition, when the continuous actual packaging of the lunch box was evaluated using a half-fold automatic packaging machine, it was found that there was no failure in the seal part and that it had good suitability for the packaging machine in a wide temperature range. Was.

Example 2

Using the resin composition shown in Table 1, a heat-shrinkable laminated film was produced in the same manner as in Example 1. The obtained stretched film was excellent in transparency and low-temperature shrinkage, and had a high tensile modulus. Also, as in Example 1, it was excellent in suitability for a packaging machine.

Example 3

Using the resin composition shown in Table 1, a heat-shrinkable laminated film was produced in the same manner as in Example 1. 500,000 ppm of monoglyceride stearate was added to the inner and outer layers as an anti-fog agent, but it has excellent transparency, low-temperature shrinkage, high tensile modulus, and packaging. It was a film with excellent adaptability.

Comparative Example 1

As shown in Table 1, linear low-density polyethylene with a melt index of 2.0 g / 10 min was used for the intermediate layer, and the inner and outer layers of Example 1 were used. Using the same linear low-density polyethylene resin as that used for the inner and outer layers, extruded under the same conditions as in Example 1, cooled, pulled off, and had a diameter of about 75 mm A raw material of a laminated unstretched film having a thickness of 320 wm was obtained. The thickness of each layer was adjusted by adjusting the screw rotation speed and take-off speed of the extruder.

This tube-shaped unstretched film was guided to the tuber biaxial stretching device shown in Fig. 1 in the same manner as in Example 1, and it was quadrupled vertically and horizontally at 95 to 105'C. The film was stretched to obtain a laminated biaxially stretched film. Next, this stretched film was treated with 75 pieces of hot air for 10 seconds in a tube-one-ring apparatus, cooled to room temperature, folded and wound up.

«Stability during stretching is not a problem, and the film obtained is transparent and has a low temperature Although it was excellent in shrinkage, it had low tensile modulus. When this film was placed on a packaging machine and evaluated for packaging suitability, resin adhesion and stringing to the fusing sealer were slightly improved, but binholes were liable to occur. Sex was inadequate.

Comparative Examples 2 and 3

The intermediate layer of Comparative Example 2 has a total heat of fusion of 132.0 mJZ mg in the melting curve, and uses a linear low-density polyethylene that is not more than 135 mJ / msr. The intermediate layer of Comparative Example 3 has an endothermic area ratio equal to or higher than the melting point in the melting curve of 11.0%, and uses a linear low-density polyethylene which is not higher than 12%. In both Comparative Examples 2 and 3, the same linear low-density polyethylene was used as in Example 1, and a heat-shrinkable laminated film was obtained in the same manner as in Example 1.

The heat-shrinkable films obtained were both excellent in transparency and low-temperature heat shrinkage in Comparative Examples 2 and 3, but had low tensile modulus. In the actual packaging test using the packaging machine, pinholes were liable to occur in the seals of both, and the sealability was insufficient.

Comparative Example 4

The middle layer uses the same linear low-density polyethylene as in Example 1, and the inner and outer layers have a melt index of 0.68T / 10 minutes and 1.0. A heat-shrinkable laminated film was obtained in the same manner as in Example 1 by using a linear low-density polyethylene not in the range of 5.0 S / 10 minutes. The resulting film has excellent low-temperature shrinkage and a large tensile modulus, and exhibits good fusing sealability even in actual packaging tests using a packaging machine. There was, however, less transparency.

Comparative Example 5

The intermediate layer uses the same linear low-density polyethylene as in Example 2, and the inner and outer layers have a total heat of fusion of 121 mJZ mg in the melting curve, and 135 to 16 A heat-shrinkable laminated film was obtained in the same manner as in Example 1 using a linear low-density polyethylene that was not in the range of 0 mJZ mg. The resulting film was excellent in transparency and low-temperature shrinkage. In the actual packaging test using a packaging machine, the tensile elasticity was slightly inferior, and resin adhesion to the heat knife and adhesion of the film to the heat knife tray were observed, and the length of the seal was about 3 mm. There was a hole in the hole, and the sealability was very unstable.

Comparative Example 6

The intermediate layer uses the same linear low-density polyethylene as in Example 1, and the inner and outer layers have a total heat of fusion of 162.4 mJZ mg in the melting curve, and 16 OmJ / A heat-shrinkable laminated film was obtained in the same manner as in Example 1 by using a linear low-density polyethylene of msr or more. The film obtained has poor stability in the stretching process, and the obtained film is inferior in transparency and low-temperature shrinkage.In actual packaging tests using a packaging machine, the seal may be easily sealed. Some pinholes were observed.

Comparative Example 7

The same linear low-density polyethylene as in Example 1 was used for both the intermediate layer and the inner and outer layers, except that the thickness of the intermediate layer was set to 50% of the total thickness. A heat-shrinkable laminated film was obtained in the same manner as in Example 1. The resulting film was excellent in transparency and low-temperature shrinkage, but had some pinholes in the seal part and was insufficiently sealable. . Industrial applicability

The polyethylene-based heat-shrinkable laminated film of the present invention is made of a material that satisfies specific conditions as a raw material for each layer, and therefore has excellent transparency and low-temperature shrinkage. In addition, it provides a shrink film excellent in suitability for packaging machines because it uses a raw material that has a high rate of cooling and solidification of the blown resin at the time of fusing sealing and that can obtain a high tensile modulus. It is. Table 11

Table 11-2

Unit Comparative Example 1 3 Comparative Example 1 Comparative Example 1 5 Comparative Example-6 Comparative Example 1 7 Comonomer 4-me jm τΒΛ Noano 14 4-methyl ぺ Noano 14 4-meter Tono τ No 14-me TflA Noano 14 4-me ΤΛΛ Noaso-1q

Medium Les density% / cm ³ 0.915 0.920 0.9Z0 0.920 between the di / "V

M l gZIO min 0.8 0.5 0.6 0.5 0.5 est

Layer Melting point c 118.8 124.3 122.5 124.3 124.3 Special heat of fusion nJ / ng 136.8 142.7 147.4 142.7 142.7 Endothermic area ratio above melting point% 11.0 15.3 13.1 15.3 15.3 Thickness ratio setting% 75 70 80 70 50 Recorder's weight-1 (4-Nut) 1 content-1 4-methyl-1 content

Inner density Density g / cra ^d 0.920 0.920 0.910 0.930 0.920 Outer M l gZIO content 1.0 0.6 2.0 0.8 1.0 layer Special total heat of fusion fflj / fflg 155.7 147,4 120.5 162.4 loo.7 14.1 13.5 12.6 Additives

Thickness ratio (inner layer)% 12.5 15 10 15 25 Thickness ratio (outer layer) I C

/ ίά> 0 1 l κo 11 nU lo 25 Product Thickness · Middle layer m 15.2 13.8 16.2 14.0 10.2 Eyebrow Inner layer ur & 2.5 3.1 2.0 2.9 5.1 Outer layer jum 2.4 3.1 1.9 2.9 5.0 Shrinkage Haze% 2.4 5.2 2.5 6.5 2.5 F Area shrinkage % 24.8 20.3 28.1 18.9 23.8 Tensile modulus kg / cnf 2700 3600 2700 3700 3100

Fusing sealability X O X

Claims

The scope of the claims

1. In Po Li et Chi Le emissions-based heat-shrinkable laminated full I le-time, density and the intermediate layer is 0.9 1 0 one ^{0. 9 3 0 gr / cm 3} > main Le preparative Lee emissions de click Temperature is 0.1 to 0.88 TZ for 10 minutes, and in the melting curve by a differential scanning calorimeter (hereinafter abbreviated as DSC), the temperature is lowered after holding for 30 minutes at 190 ° C. The temperature was lowered to 20 at a rate of 10 / min, and then the total heat of fusion in the melting curve obtained when the temperature was raised at a rate of 1 O'CZ was 135 mJ / linear low-density polyethylene whose endothermic area is at least 12% of the total endothermic area and is not less than mgr and the main peak temperature (melting point) or higher.

At least one layer composed of a composition containing (A) as a main component, a density of 0.910 to 0.93 grZ cm ³ , and a melt index 0.8 to 5.Og ZIO, and the total heat of fusion in the melting curve is in the range of 135 to 160 mJ Zmsr, and is higher than the main beak temperature. Layers composed of a composition mainly composed of linear low-density polyethylene (B) having an endothermic area of at least 12% of the total endothermic area are included as the innermost layer and the outermost layer, respectively. Polyethylene-based heat-shrinkable laminated film characterized by this.

2. Ri Der thickness of the intermediate layer 6 0% or more against the entire thickness, tensile modulus 3 0 0 0 k sr Z cm ² or more, 9 0 put that area shrinkage hands 2 0% or more The polyethylene-based heat-shrinkable laminated film according to claim 1, wherein the film is biaxially stretched.

3. The linear low-density polyethylenes (A) and (B) are characterized by having ethylene as the main component and an α-age olefin having 4 to 8 carbon atoms. The polyethylene-based heat-shrinkable laminated film according to claim 1.