JPH1034847A - Polyolefin resin multilayer stretched film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a film which has so-called nerve even in case of a thin thickness and no packaging trouble in a packaging machine and can heat seal by constituting both surface layers by copolymer composition containing propylene, ethylene and specific olefin. SOLUTION: The multilayer stretched film comprises at least four layers of both surface layers, an oriented auxiliary layer and a core layer in such a manner that mean 100% elongation load in lateral and longitudinal directions is 100 to 600g/cm width. Both the surface layers are formed of a copolymer composition containing propylene, ethylene and at least one type of 4-8C α-olefin. In rectangular coordinates in which a melting point of the copolymer composition is an abscissa axis and a bending elastic modulus (kg/mm<2> ) is an ordinate axis, the copolymer composition is in a range of connecting three points of coordinate points A (120, 45), B (145, 45) and C (145, 100) by straight lines.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a multilayer stretch film of a polyolefin-based resin, and more particularly to a multilayer stretch film of a polyolefin-based resin mainly used for packaging materials.

[0002]

2. Description of the Related Art Conventionally, at least four layers (for example, Z / X / Y / Z) composed of both surface layers (Z layer), a stretching auxiliary layer (X layer) and a core layer (Y layer) are used. A polyolefin-based resin multilayer stretch film for packaging having a% elongation load of 100 to 600 g / cm in average in the vertical and horizontal directions is disclosed in Japanese Patent Publication No. 2-52624 and known. According to the description in this publication, the surface layer (Z layer)
Is intended to provide a multilayer film with surface properties such as heat sealing properties, anti-fog properties, and surface glossiness. For example, EVA (ethylene-vinyl acetate copolymer) and EMAA (ethylene-
Synthetic resins such as methacrylic acid copolymer) are employed.

The core layer (Y layer) mainly provides heat resistance and mechanical strength to the entire multilayer film. For example, crystalline polypropylene (IPP) and polybutene-1 (PB)
-1) and the like. In addition, the stretching auxiliary layer (X
The layer) is a layer that plays a role of facilitating the stretching of the Y layer, which is difficult to stretch at a low temperature of, for example, 30 to 80 ° C. in a single layer, such as a mixed resin layer of EVA, PP, and a soft polymer. It is.

When the X layer is disposed close to the Y layer, the entire multilayer film is kept at 30 to 80 ° C.
Under low temperature, it is possible to stretch 5 to 30 times in area ratio (referred to as cold stretching), and as a result, the quality characteristics of a multilayer film as a stretch film for packaging, that is, for example, Moderate elongation load in elongation (100% elongation load is 100 on average in the longitudinal and lateral directions)
Elongation at break = stretchability "," transparent and glossy = display characteristics "," heat sealable over a wide temperature range = heat sealability ",
It has succeeded in having "there is a waist and has sufficient mechanical strength = operability with packaging machine".

[0005] Therefore, this multi-layer film can be used, for example, in a tray container formed of a synthetic resin or a foam of the resin, for example, meat,
It can be used in the field of stretch packaging in which fish, vegetables, prepared foods, etc. are put into use and the film has a "moderate elongation load and high breaking elongation at a specific elongation".
Here, as an example of stretch packaging, an outline of a method of wrapping an article to be packaged placed on a tray using a stretch film with a straight-type packaging machine will be described with reference to FIG.

FIG. 2 is a conceptual diagram of a process of continuously packaging a tray on which an article to be packaged is placed using a conventional film by a straight-type packaging machine. I, II, II from the left in the order of the packaging process
I, IV, V and VI are shown separately in six steps.
"I" is drawn out from the film roll (1) while pulling the film (2) from the film roll (1) with the belt (21) stretching laterally across both sides of the film, and using the fed film (3), the tray (11). Is wrapped from above.

"II" is a film (3) fed out
After both sides (5) of the tray (12) are joined by the bag making plate (22) at substantially the center of the bottom of the tray (12) and sealed with the center sealer (23), the folding plate (24)
Is a state where the portion sealed to the tray bottom is folded. "III" shows a state after the film connected to the front and back of the tray is cut by the cutter (25). At this time, the air in the end (hereinafter referred to as an ear) of the film in front of the tray (6) is trapped, and the upper surface of the tray often expands as in (7).

"IV" is the back ear (8) of the tray (13).
Is folded into the bottom of the tray (13) by the ear-folding roller (26) while being sucked by the rear ear-folding nozzle (27). "V" is a state in which the front ear (9) of the tray (13) is folded into the bottom of the tray (13) by the shutter (29) while being sucked by the front ear folding nozzle (28). At this time, the air held in the front ear (6) is sucked out by the front ear folding nozzle (28) and escapes, and the bulge of (7) disappears.

In the case of "VI", the tray (14) wrapped with film is transported by the chute conveyor (30), and the tray (1) is moved by the heater (31) on the way.
This is a state where the film folded into the bottom of 4) is heat-sealed. Through the above steps, the conventional film having both "stretching property", "heat sealing property", "operability with a packaging machine" and the like can cleanly package an object to be packaged.

On the other hand, there is an increasing demand for thinner packaging films from the viewpoint of resource saving and environmental issues. For example, stretched plasticized polyvinyl chloride films having a thickness of about 16 μm in the past have been increased to 14 μm. At present, it is becoming as thin as about 13 μm. Also, in general,
The thickness of the polyolefin resin stretch film is about 11 to 15 μm.

[0011]

However, when a conventional film is reduced in thickness to, for example, about 9 μm, it is difficult to cleanly package the film with a linear packaging machine because the mechanical strength and particularly the waist are greatly reduced. . In particular, it is known that the “hip” of a film is proportional to the cube of the thickness, and the loop stiffness (hereinafter abbreviated as LS, which is an index representing the waist; a measuring method will be described later)
For example, in a conventional film, the LS is about 4.3 mg when the thickness is 12 μm, whereas the LS is about 1.8 mg when the thickness is 9 μm. Below (approximately 1 / 2.4).

Here, the problem in the case where the stiffness of the film becomes small will be specifically described with reference to FIG. First, in step "I", both ends (5) of the film rubbed by the bag-making plate are likely to curl if the film has no stiffness, and if both ends (5) of the film are curled, the film will not join and the center sealer ( The sealing according to 23) cannot be performed.

In step "III", the front ears (6) of the cut film are moved while moving.
If the tip is easily rounded due to rubbing, and even if the front ear is slightly rounded, the front ear is not sucked even if it is sucked by the front ear folding nozzle (28) in the step "V", so that the shutter (2)
9) makes it impossible to fold into the bottom of the tray (13). Even if the front ear is not rounded, a film without a waist easily adheres (the contact area becomes large), so even if the film is sucked by the front ear folding nozzle (28), it is held in the front ear (6). The air that has been trapped does not escape and the swelling (7) tends to remain. This causes loose wrinkles when the packages (14) are stacked.

In the above-mentioned straight type packaging machine, in the case of the conventional film, if the thickness is more than 12 μm, it can be neatly packaged without any problem, but the thickness is 10 μm (LS = 2.4 mg).
In the following, the above-described problem tends to occur easily. Accordingly, the present invention relates to the conventional excellent properties such as the anti-fog property and strength of the above-mentioned multilayer film, and particularly, “a moderate elongation load at a specific elongation (100% elongation load is 1% on average in the machine direction and the transverse direction).
High elongation at break as high as 0.00 to 600 g / cm) and the optical properties are maintained, and even if the thickness is as thin as 7 μm, the value of the loop stiffness is 2.5 mg or more = waist.
Accordingly, it is an object of the present invention to provide a film which can be heat-sealed without any packaging trouble particularly in a linear packaging machine.

[0015]

The inventor of the present invention has made intensive studies to solve the above-mentioned problems of the prior art, and as a result, has reached the present invention. That is, the present invention comprises at least four layers of both surface layers (Z layer), an auxiliary stretching layer (X layer) and a core layer (Y layer), and the 100% elongation load is 100 to 100% on average in the longitudinal and transverse directions. In the multilayer stretch film having a width of 600 g / cm, the both surface layers (Z layers) are a copolymer composition comprising propylene, ethylene, and at least one α-olefin having 4 to 8 carbon atoms, When the flexural modulus (kg / mm ² ) is represented by the vertical axis y and the melting point (° C.) of the copolymer composition is represented by the rectangular coordinates (x, y) represented by the horizontal axis x, the coordinate point A (120, 45), B (145, 4
5) A polyolefin-based resin multilayer stretch film containing a copolymer composition in a range connecting three points of C (145, 100) with a straight line.

Hereinafter, the contents of the present invention will be described in detail. The present invention is different from the prior art in that both surface layers (Z layers) of the “multilayer film” include “propylene and ethylene having at least a specific range of flexural modulus and melting point and at least one carbon number of 4 or more.
(Hereinafter, abbreviated as a terpolymer composition) consisting of α to olefins of 10 to 10).

First, the most different points between the present invention and the prior art will be described with reference to Table 1. Table 1 shows the properties of the resin used for the surface layer (Z layer) of the multilayer film, and the "10
0% elongation load "," loop stiffness (LS) "as a measure of the waist of the film, and the evaluation results of the film. Table 1
Are the film of the present invention (corresponding to Experiment No. 1 in Example 1), the conventional film (corresponding to Experiment No. 2 in Comparative Example 1), and the ternary film used for the skin layer of the film of the present invention. The values of three kinds of films of the single layer film of the polymer composition (PEB1) (corresponding to Experiment No. 3 of Comparative Example 2) are shown.
The thickness of each film is 9 μm.

In Table 1, the film of the present invention is 100
% Elongation load 360g / cm width in the vertical direction, 110g in the horizontal direction
/ Cm width (235 g / cm width on average in vertical and horizontal directions)
It has a moderate elongation load and LS of 3.4 mg has enough waist, so even though it is thin, 9 μm, it can be used for packaging with a linear packaging machine without any trouble and wrinkles. It could be packed neatly without any. In addition, optical characteristics (Haze =
1.0%) and heat sealing properties (ΔT = 20 ° C.).

On the other hand, in the conventional film, the 100% elongation load is a moderate elongation load of 350 g / cm width in the vertical direction and 90 g / cm width in the horizontal direction (average width of 220 g / cm in the vertical and horizontal directions). The LS was as small as 1.8 mg and had no waist. Therefore, the front ear was rubbed with the ear-folding roller and rounded, and could not be folded into the tray bottom. Further, there is a problem that the sliding with the metal parts of the machine is poor, and the film often breaks.

Further, it is difficult to perform cold stretching with a single layer of the terpolymer composition (PEB1), which is “a rigid resin = hard resin”, and the stretching temperature is as high as 130 ° C., and thus the LS is 7.0 m.
g and waist, and there was no problem in film transportability,
100% elongation load is 980g / cm width in vertical direction, 4 in horizontal direction
20g / cm width (700g / c on average in vertical and horizontal directions)
m width), and the stretch load is large and the stretchability is inferior. Therefore, there is a problem that the tray is crushed under the same packaging conditions as the film of the present invention, and wrinkles remain if the tension conditions are weakened so that the tray is not crushed. In addition, the optical characteristics (Haze = 2.
5%) and heat sealability (ΔT ≦ 5 ° C.).

From the above, it can be seen that the film of the present invention can improve the waist while maintaining the excellent properties of the conventional film, particularly the stretchability, in combination with the above requirements. Therefore, the role of the “multilayer film” as a requirement is to maintain the stretchability and the optical characteristics, which are the characteristics of the conventional film, and to bring the heat seal characteristics to a practical level.

The layer structure of the film of the present invention is such that cold stretching can be performed, and the film is stretched (cold stretching) at an area magnification of 6 to 30 times at a low temperature of 30 to 80 ° C. Even when a hard resin such as a terpolymer composition (PEB1) is used for the surface layer (Z layer), the stretchability = 100% elongation load as in the film of the present invention is 1 in average in the longitudinal and transverse directions.
00 to 600 g / cm width ".

In order to form a multi-layer structure, “a rigid resin = a hard resin” is applied to a thin layer (Z layer) on the surface of a multi-layer film.
Since it can be used only for "waist", there is an advantage that "stretch" can be maintained even if "hip" is greatly improved. The cold-stretched film has a low-temperature shrinkage property. Specifically, the shrinkage at 80 ° C. is at least 15% on average in the vertical and horizontal directions.

Next, the requirement “propylene and ethylene having at least a specific range of flexural modulus and melting point, and at least 1
The role of the "copolymer composition comprising an α-olefin having 4 to 10 carbon atoms" will be described. FIG. 1 is an analysis diagram of the present invention. The vertical axis represents the flexural modulus of the terpolymer composition, the horizontal axis represents the melting point of the terpolymer composition,
It is a plot of the experimental results (packing suitability, heat sealability, optical properties) shown in Tables 1 and 2 in relation to the physical properties of the used terpolymer composition. The symbol “◎” indicates that the overall evaluation was “◎”, the symbol “○” indicates that the overall evaluation was “○”, and the symbol “×” indicates that the overall evaluation was “×”.
Was represented.

As is apparent from FIG. 1, it can be seen that the regions satisfying all of the suitability for packaging, heat sealing properties and optical properties can be separated by lines. Here, when FIG. 1 is compared with the evaluation results in Tables 1 and 2, the following can be understood. That is,
The area below the straight line connecting the point A (120, 45) and the point B (145, 45) is an area in which a trouble during transportation occurs and the suitability for packaging is poor. When the flexural modulus of the terpolymer composition used for the Z layer is less than 45 kg / mm ² , the LS of the film is less than 2.5 mg, and as a result, it is considered that a transport trouble has occurred.

The points B (145, 45) and C (14
The area on the right side of the straight line connecting (5, 100) is an area inferior in heat sealability. As the melting point of the terpolymer composition used in the Z layer increases, the lower limit temperature at which heat sealing is possible tends to increase. However, when the melting point of the terpolymer composition exceeds 145 ° C., the film has a melt hole. 5 ° C from the temperature at which heat occurs (= the upper limit temperature at which heat sealing is possible)
(Limit range for practical heat-sealing).

Next, point A (120, 45) and point C (14
The region above the straight line connecting (5, 100) is a region having poor optical characteristics. The terpolymer composition in this region is not a random copolymer but a block or graft copolymer, and it is considered that the composition itself is milky white. Here, in the random copolymer of ethylene and propylene, the melting point x (° C.) and the flexural modulus y (kg / mm
² ) and Y 関係 2.3X-229.

From the above, the region surrounded by the straight line connecting the coordinate points A, B, and C indicates the suitability of the film for packaging, optical characteristics,
It can be seen that a region satisfying all the heat sealing properties is shown. Further, point D (127, 60) and point E (135, 6)
0), the area surrounded by the point F (135, 78) is the area where the overall evaluation is “◎”, and is preferable because it has further enhanced film characteristics.

Next, the film of the present invention must have a 100% elongation load of 100 to 600 cm / width on average in the longitudinal and transverse directions from the viewpoint of stretchability. Since the film of the present invention is cold-stretched, when the film is stretched in one direction, stress is propagated in all directions and wrinkles can be removed even with a slight stretch ratio, and packaging can be performed tightly. However, when the above value is less than 100 g / cm width, this effect is small, and the film is easy to stretch but does not remove wrinkles. Also 60
With a film exceeding 0 g / cm width, the tray is crushed when trying to pack tightly, and when the tension of the packaging machine is reduced so that the tray is not crushed, wrinkles cannot be removed.

Here, as a specific example of the terpolymer composition having the above-mentioned flexural modulus and melting point in a specific range, at least a two-step process disclosed in JP-A-8-48837 and EP06749991A1 is disclosed. And a ternary copolymer composition polymerized in the above. The specific composition is
a) After polymerizing a random copolymer of ethylene or butene-1 and propylene, b) polymerizing a random copolymer of propylene-ethylene or propylene-ethylene-α-olefin having 4 to 8 carbon atoms, This is a terpolymer composition in which a rigid copolymer polymerized in the second stage is finely dispersed on the order of microns or less in a rigid copolymer polymerized in the first stage. Preferably, a1) 20 to 60% by weight of an ethylene-propylene random copolymer component containing 1 to 5% by weight of ethylene, and b2) 1 to 5% by weight of ethylene.
Α-olefin having 4 to 8 carbon atoms by weight and 6 to 1
The propylene-ethylene-α-olefin random terpolymer component containing 5% by weight is 40 to 80% by weight, and the proportion of ethylene in the total amount of the copolymer composition is 1 to 5% by weight.
And α-olefin having 4 to 8 carbon atoms is 2.4 to 12
A terpolymer composition comprising propylene, ethylene and at least one α-olefin having 4 to 8 carbon atoms by weight.

The terpolymer composition comprising propylene, ethylene and at least one α-olefin having 4 to 8 carbon atoms has a melt flow rate (from the viewpoint of preventing interlayer disturbance during multilayer extrusion and film strength). MFR; JIS K
7210 compliant. 230 ° C, load 2.16kg) is 1.0
MFR is preferably 3.0 to 10.0 g / 10 minutes from the balance of physical properties of the film in the vertical and horizontal directions.

The Z layer has a density of 0.910 g / cm ³ or less for the purpose of improving anti-fogging property, sliding property, heat sealing property, etc. within a range that does not impair the properties of the terpolymer composition. EVA, EMAA, etc. having a melting point of 100 ° C. or less may be blended. In addition,
When other components are blended, the flexural modulus is the value of the composition after blending.

The thickness of the Z layer (one layer) is usually selected at a composition ratio of 5 to 20% with respect to the thickness of the multilayer film. Z
The absolute thickness of the layer is usually selected in the range of 0.1 to 3 μm.
Next, the stretching auxiliary layer and the core layer constituting the multilayer film will be described. First, the X layer, which is a stretching auxiliary layer, is an essential layer when performing cold stretching. This layer is a layer mainly composed of a blend composition of the following three types of polymer (L), polymer (M), and polymer (N).

The polymer (L) is a soft elastomer or plastomer having a Vicat softening point of 60 ° C. or less,
Specific examples thereof are mainly random copolymers of ethylene or propylene and α-olefins having 2 to 20 carbon atoms. Here, in addition to the α-olefin, a cyclopentadiene-based monomer, a norbornene-based monomer (for example, ethylidene norbornene), or the like may be copolymerized. Preferably, it is a copolymer of ethylene and octene polymerized with a single-site catalyst such as metallocene from the viewpoint of extrusion characteristics and antifogging property.

The polymer (M) is, for example, firstly to have a density of 0.860 to 0.925, ethylene and carbon number 4 in order to impart elongation, transparency and antifogging property. ~
8 (preferably 6 or 8) copolymer with α-olefin, secondly, ethylene and ester monomers such as ethylene-vinyl acetate and ethylene-ethyl acrylate, aliphatic unsaturated monocarboxylic acid, Thirdly, at least a part of a copolymer obtained by saponifying at least a part of a copolymer of a monomer selected from a monocarboxylic acid alkyl ester and at least a part of a copolymer of the above monomer and ethylene with Na, Zn , Mg, and the like, and a polymer ion-bonded with ions of a metal.

The polymer (N) may be, for example, a homopolymer or a polypropylene polymer obtained by copolymerizing propylene with ethylene or butene-1 or the like in order to impart strength (rigidity) or heat resistance to the film. -1 is a polybutene-1 polymer in which ethylene, propylene or the like is copolymerized. The above composition may be blended with a petroleum resin such as 1,2-polybutadiene, hydrogenated dicyclopentadiene, hydrogenated terpene, hydrogenated styrene-butadiene copolymer (block, random) and the like.

Next, the Y layer for maintaining heat resistance and strength is made of, for example, a homopolymer and a polypropylene polymer obtained by copolymerizing propylene with ethylene and butene-1, and a copolymer of butene-1 with ethylene and propylene. Made of polybutene-1 based polymer and the like. In particular, the Y layer may be a layer containing at least 50% by weight of a polybutene-1 resin having an MI (190 ° C., 2.16 kg) of 2 or less in order to improve the lateral tearing property (cutting property of the film). preferable. As a resin to be mixed in addition to these resins,
Examples include petroleum resins such as 1,2-polybutadiene, hydrogenated polydicyclopentadiene, and hydrogenated polyterpene, and hydrogenated styrene-butadiene copolymer (block, random).

As a combination of these layers, Z / Y / X / Z for four layers, Z / X / Y / X / Z, and Z / Y for five layers
/ X / Y / Z, Z / X / Y / X / Y / X / Z for 7 layers,
Z / Y / X / Y / X / Y / Z, Z / Y / X /.../ Z, Z
/X/Y/.../Y/Z and the like. Preferably, Y
It is a combination having two or more layers. The above film is
It can be recovered, re-pelletized and blended into the X layer.

The thickness ratio of each layer is usually 10 layers for the X layer due to the strength, optical properties and heat sealing properties of the multilayer film.
85%, the Y layer is selected in the range of 5-40%, and the Z layer is selected in the range of 5-20%. In addition, the total thickness of the multilayer film is usually 5 to 15 μm from the viewpoint of wrapping properties (hand wrapping, mechanical wrapping such as push-up wrapping machines and linear wrapping machines), stretchability and handleability. Preferably it is 7 to 12 μm. In particular, the effect of the present invention is remarkable at a thickness of 10 μm or less. Note that the effect of the present invention is remarkably exhibited at 10 μm
The following is the case.

The X layer and the Z layer may contain an antifogging agent, an antibacterial agent, a defrosting agent, an ultraviolet absorber, an antioxidant, and the like. The emulsion, surfactant, powder, polymer or the like may be coated. Next, a cold stretching method as a preferred method for obtaining the film of the present invention will be described. First, the resin composition of each layer is melt-extruded by a separate extruder, and combined and laminated by a multilayer die (preferably a circular die). This laminate is quenched and solidified by a refrigerant to form a tubular raw material. Thereby, the crystallinity of each resin layer is suppressed low, and cold stretching is facilitated. At this time, it is preferable to fill the tube with a surfactant, silicone oil, or the like for the purpose of improving properties such as antifogging property and slipperiness. Next, 30-80 ° C (usually 35-6
(5 ° C.) and stretched to an area magnification of 6 to 30 times. After the stretching, the film is taken and subjected to a heat treatment if necessary. Further, a corona discharge treatment or the like may be performed after the heat treatment.
Methods for measuring and evaluating physical properties of the resin and the like in the present invention are as follows. (1) Melting point According to JIS-K7121, DSC-7 manufactured by PerkinElmer was used as a measuring device. The sample amount was 10 mg, the temperature rise rate and the temperature decrease rate were 10 ° C./min, and the measurement temperature was −
The holding time at 10 ° C to 200 ° C was 5 minutes.

The melting point was indicated by the peak temperature of the highest peak (main peak) among the melting peaks. (2) Flexural modulus The measurement was performed in accordance with JIS K-7203. The sample is 127mm long x 12.7mm wide x 5m by injection molding.
The thickness was adjusted to 24 m in a constant temperature room at 23 ° C ± 2 ° C, and the measurement was performed at a bending speed of 25 mm / min. (3) Shrinkage at 80 ° C. A film sample was 100 mm × 10 in the vertical and horizontal directions.
Cut to 0 mm, 80 with the film shrinking freely
It was left for 30 minutes in a hot air circulating thermostat at ℃. After 30 minutes, the sample was taken out, the dimensions in the vertical and horizontal directions were measured, and the shrinkage was determined.
In the table, the average values in the vertical and horizontal directions are shown. (4) Elongation load The sample film is 10 mm wide x 1 in the vertical and horizontal directions.
The sheet was cut into a length of 00 mm, and a 100% elongation load was measured by a tensile test with a load cell. The measurement conditions were as follows: the distance between the chucks was 50 mm, the tensile speed was 200 mm / min, and the measurement temperature was 23 ° C. ± 1 ° C. (5) Loop stiffness (LS) The loop stiffness is such that a film is set in a loop shape and a load (mg) when the loop is crushed is used as an index of the waist of the film. For the measurement, a loop stiffness tester manufactured by Toyo Seiki Seisaku-sho, Ltd. was used. The sample size was 25 cm in length and 2.5 cm in width in the vertical direction, and the effective loop length was 50 mm. (6) Optical properties; Haze Evaluation method Measured in accordance with ASTM-D1003.・ Evaluation Criteria Criteria Symbol Remarks Haze <1.0% ◎ Excellent transparency 1.0 ≦ Haze <2.0% ○ Level with no practical problem (the above is acceptable level) 2.0 ≦ Haze <3.0% △ Practical problem remains at a level where whiteness of the film is a concern.

Haze> 3.0% × The whiteness of the film is conspicuous. (7) Packaging suitability and evaluation method SP-3, a linear stretch packaging machine manufactured by Ibaraki Seiki Co., Ltd.
000 (improved type), 100 pieces of the following three types of FP Corporation foam (PSP) trays loaded with 200 g of clay are packed at a packing speed of 55 packs / min, and 98 or more are wrinkled or torn in the film. Those that were cleanly packaged with no occurrence were judged as acceptable.

Alpha: 196 L × 196 W × 25 H (mm) —Packaging is the most difficult. P-3: 218L x 150W x 22H (mm) ... The packaging property is between the upper and lower sides. F-6: 161L x 95W x 17H (mm) ... Easiest packaging.・ Evaluation criteria Scale Symbol Remarks All three types of trays have passed ◎ Tray with difficult shape is also possible Two types of trays have passed ○ Level that can be used in normal use (more than acceptable level) One type of tray Is acceptable △ Can be used only for easy packaging × All failed × Unsuitable for practical use (8) Heat sealing properties ・ Evaluation method 100 g of viscosity was placed on the tray of No. 6 and wrapped with a sample film using a linear packaging machine. This was placed on a hot plate whose temperature had been set in advance for 2 seconds, and the state of heat sealing was observed. The minimum temperature at which the film is completely sealed is defined as the seal lower limit temperature (T1), and the temperature at which the film begins to melt and a hole is formed is defined as the seal upper limit temperature (T2), and ΔT = T2
-T1 was set.・ Evaluation criteria Scale Symbol Remark ΔT ≧ 20 ℃ ◎ Excellent heat sealability 10 ℃ ≦ ΔT <20 ℃ ○ Heat seal has no practical problems (passing level) 5 ℃ ≦ ΔT <10 ℃ △ Temperature range is narrow and practical Difficult ΔT <5 ° C × Unusable-Those that could not be sealed (including those that could not be packaged) (9) Anti-fog property ・ Evaluation method Place 200 g of pork loin slices on PSP tray FS-B5 manufactured by Chuo Chemical Co., Ltd. They were wrapped in film and displayed in an open showcase at about 5 ° C. for one day, and then observed.・ Evaluation criteria ◎: The water film is uniform and the contents look beautiful ○: There are some large water drops but the contents look beautiful △: The contents look distorted by water drops ×: The film is pure white Those in which the contents are not visible (10) Comprehensive evaluation-Evaluation method This is a summary of four evaluation items of optical properties, packaging suitability, heat sealing properties, and anti-fog properties.・ Evaluation criteria Scale Symbol Remarks All four evaluation results are “◎” ◎ Most suitable for practical use Four evaluation results are “◎” or “○” ○ Practical use level Even if only one of the four evaluation results is “△” Includes △ Not suitable for practical use Even if one of the four evaluation results contains “x” × Impossible

[0044]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. First, the polymer used in this example is shown below. PEB1: propylene-ethylene-butene-1 terpolymer composition [flexural modulus = 70 kg / mm ² , melting point =
132 ° C. (melting peak 1 = 101 ° C., melting peak 2 = 1
32 ° C., melting peak 3 = 143 ° C., crystallization temperature = 87
° C), density = 0.89 g / cm ³ , MFR = 5.5 g / cm ³
10 minutes (equivalent to KT-221P manufactured by Montell)] PEB2: propylene-ethylene-butene-1 terpolymer composition [ethylene-propylene random copolymer component having an ethylene content of 7.5% by weight Is 70% by weight
And propylene-ethylene-butene-1 having an ethylene content of 3.2% by weight and a butene-1 content of 8.8% by weight.
A composition comprising 30% by weight of a random copolymer component. Flexural modulus = 40 kg / mm ² , melting point = 119 ° C., density =
0.89 g / cm ³ , MFR = 4.0 g / 10 min] PEB3: propylene-ethylene-butene-1 terpolymer composition [ethylene-propylene random copolymer having an ethylene content of 7.0% by weight] 90% by weight of polymer component
And propylene-ethylene-butene-1 having an ethylene content of 3.2% by weight and a butene-1 content of 8.8% by weight.
A composition comprising 10% by weight of a random copolymer component. Flexural modulus = 45 kg / mm ² , melting point = 120 ° C., crystallization temperature = 81 ° C., density = 0.90 g / cm ³ , MFR = 5.
0 g / 10 min] PEB4: Propylene-ethylene-butene-1 terpolymer composition [90% by weight of an ethylene-propylene random copolymer component having an ethylene content of 4.7% by weight]
Propylene-ethylene-butene-1 having an ethylene content of 3.0% by weight and a butene-1 content of 8.3% by weight
A composition comprising 10% by weight of a random copolymer component. Flexural modulus = 60 kg / mm ² , melting point = 127 ° C., density =
0.90 g / cm ³ , MFR = 4.5 g / 10 min] PEB5: propylene-ethylene-butene-1 terpolymer composition [ethylene-propylene random copolymer having an ethylene content of 4.0% by weight] 30% by weight of polymer component
Propylene-ethylene-butene-1 having an ethylene content of 3.0% by weight and a butene-1 content of 8.3% by weight
A composition comprising 70% by weight of a random copolymer component. Flexural modulus = 40 kg / mm ² , melting point = 133 ° C., density =
0.89 g / cm ³ , MFR = 4.5 g / 10 min] PEB6: propylene-ethylene-butene-1 terpolymer composition [butene-1 having a butene-1 content of 15.5% by weight The propylene random copolymer component is 50
A composition comprising 50% by weight of an ethylene-propylene random copolymer component having an ethylene content of 4.6% by weight and 4.6% by weight. Flexural modulus = 65 kg / mm ² , melting point = 133
° C, density = 0.89 g / cm ³ , MFR = 4.5 g / 1
0 minutes] PEB7: propylene-ethylene-butene-1 terpolymer composition [95% by weight of ethylene-propylene random copolymer component having an ethylene content of 3.3% by weight]
Propylene-ethylene-butene-1 having an ethylene content of 3.3% by weight and a butene-1 content of 8.8% by weight
A composition comprising 5% by weight of a random copolymer component. Flexural modulus = 78 kg / mm ² , melting point = 135 ° C., density = 0.
90 g / cm ³ , MFR = 5.5 g / 10 min] PEB8: Propylene-ethylene-butene-1 terpolymer composition [ethylene-propylene random copolymer having an ethylene content of 3.3% by weight 40% by weight of ingredients
Propylene-ethylene-butene-1 having an ethylene content of 3.3% by weight and a butene-1 content of 8.8% by weight
A composition comprising 60% by weight of a random copolymer component. Flexural modulus = 60 kg / mm ² , melting point = 135 ° C., density =
0.90 g / cm ³ , MFR = 3.5 g / 10 min] PEB9: propylene-ethylene-butene-1 terpolymer composition [ethylene-propylene block copolymer having ethylene content of 2.0% by weight] 95% by weight of polymer component
And propylene-ethylene-butene-1 having an ethylene content of 2.0% by weight and a butene-1 content of 7.0% by weight.
A composition comprising 5% by weight of a random copolymer component. Flexural modulus = 95 kg / mm ² , melting point = 140 ° C., crystallization temperature = 91 ° C., density = 0.90 g / cm ³ , MFR = 6.0
g / 10 min] PEB10: Propylene-ethylene-butene-1 terpolymer composition [40% by weight of ethylene-propylene random copolymer component having an ethylene content of 2.9% by weight and ethylene content Propylene-ethylene-butene having a butene-1 content of 2.8% by weight
(1) A composition containing 60% by weight of a random copolymer component. Flexural modulus = 95 kg / mm ² , melting point = 143 ° C., crystallization temperature = 91 ° C., density = 0.90 g / cm ³ , MFR =
5.8 g / 10 min] PEB11: Propylene-ethylene-butene-1 terpolymer composition [90% by weight of ethylene-propylene random copolymer component having an ethylene content of 1.7% by weight and ethylene Propylene-ethylene-butene having a content of 3.2% by weight and a butene-1 content of 8.8% by weight.
A composition in which 1 random copolymer component is 10% by weight. Flexural modulus = 100 kg / mm ² , melting point = 145 ° C., density = 0.89 g / cm ³ , MFR = 8.0 g / 10 minutes] PEB12: propylene-ethylene-butene-1 terpolymer composition [ 40% by weight of an ethylene-propylene random copolymer component having an ethylene content of 1.7% by weight, 5.8% by weight of an ethylene content, and propylene-ethylene having a butene-1 content of 8.8% by weight. −Butene−
(1) A composition containing 60% by weight of a random copolymer component. Flexural modulus = 45 kg / mm ² , melting point = 145 ° C., density =
0.88 g / cm ³ , MFR = 8.0 g / 10 min] PEB13: Ethylene-propylene copolymer composition [Ethylene-propylene random copolymer component having 1.5% by weight of ethylene is 50% by weight. And a propylene-ethylene-butene-1 random copolymer component having an ethylene content of 6.0% by weight and a butene-1 content of 8.8% by weight, and a composition comprising 50% by weight. Flexural modulus = 50kg
/ Mm ² , melting point = 146 ° C., density = 0.88 g / c
m ³ , MFR = 5.0 g / 10 min] PEB14: Ethylene-propylene copolymer composition [Ethylene-propylene random copolymer component having 1.5% by weight of ethylene is 80% by weight and ethylene content. Is 3.2% by weight and a propylene-ethylene-butene-1 random copolymer component having a butene-1 content of 8.8% by weight is 20% by weight. Flexural modulus = 90kg
/ Mm ² , melting point = 146 ° C., density = 0.90 g / c
m ^3, MFR = 5.0g / 10 min] · EVA: ethylene - vinyl acetate copolymer [vinyl acetate group content = 15 wt%, MI = 1.0 g / 10 min, melting point =
94 ° C (equivalent to NUC7358 manufactured by Nippon Unicar)] • IPP: crystalline polypropylene [density = 0.90 g /
cm ³ , MFR = 4.0 g / 10 min, melting point = 163 ° C.
(Equivalent to Y1300 manufactured by Nippon Polyolefin Co., Ltd.)] PB-1: butene-1 propylene copolymer [density =
0.90 g / cm ³ , MI = 1.0 g / 10 min, melting point =
71 ° C. (M2181 equivalent product of Mitsui Petrochemical Co., Ltd.)] TPO: ethylene-octene-1 copolymer [octene-1 content: 25% by weight, density = 0.868 g / cm ³ ,
MI = 0.5 g / 10 min, melting point = 56 ° C., Mw / Mn =
2.7, MIR = 30 (ENGAGE manufactured by Dow Chemical Company)
・ EG8150 equivalent)] ・ VL1: Ethylene-hexene-1 copolymer [density =
0.912 g / cm ³ , melting point = 118 ° C., MI = 0.8
g / 10 minutes (Sumikasen α · FZ10 manufactured by Sumitomo Chemical Co., Ltd.)
2-0 equivalent)]

[0045]

EXAMPLE 1 Diglycerin laurate and glycerin were used as antifogging agents in a composition obtained by blending 65% by weight of EVA, 5% by weight of IPP, 5% by weight of PB-1 and 25% by weight of TPO as the X layer. 1. 1: 1 mixture with oleate
The layer to which 0% by weight is added is used as a Y layer, and IPP is 50% by weight.
And a composition layer obtained by blending PB-1 with 50% by weight,
1.0% of a 1: 1 mixture of diglycerin laurate and glycerin oleate as an anti-fog agent was added to PEB1 as a Z layer.
Each layer was Z / X / Y / X / Z
(= 10% / 35% / 10% / 35% / 10%) Extruded from a circular multilayer die (lip diameter: 200 mm, lip opening: 0.8 mm) heated to 210 ° C. in a five-layer structure ( The total extruded amount was 15 kg / hour), and the extruded laminate was rapidly cooled with cold water of 15 ° C. and folded to obtain a raw material having a thickness of 40 μm. Here, an aqueous solution of fatty acid sodium was applied to the inner surface of the raw material tube (solid content: about 5 mg /
m ² ). 3. Inject air into the folded web to form a tube, heat to 50 ° C, cool with 15 ° C air, 2.5 times in the vertical direction (TUR) and 4 times in the horizontal direction (BUR).
After 5 times tubular stretching, the tube was folded by a roll type deflator having an opening of 45 °, and was taken up by a take-off roll having a speed ratio of the deflator to the main pinch roll of 0.90. Next, the temperature was 60 ° C., the relaxation rate was 10% in length and 3% in width.
After heat treatment at 0%, both ends of the film were cut off and wound as two films. The final magnification of the film was about 2.1 times the length and about 2.1 times the width. The thickness of the final film was 9 μm (Experiment No. 1).

[0046]

Comparative Example 1 The same experiment as in Example 1 was repeated except that PEB1 used for the Z layer in Example 1 was changed to EVA described above.
A film having a thickness of 9 μm was obtained (Experiment No. 2).

[0047]

Comparative Example 2 PEB1 used in Example 1 was independently extruded from a circular die and cooled in the same manner as in Example 1 to obtain a raw material having a thickness of 100 μm. It should be noted that a raw material thinner than 100 μm could not be obtained due to draw resonance. Next, the stretching operation was performed in the same manner as in Example 1, but the stretching could not be performed. Therefore, the heating temperature is raised from 50 ° C to 13 ° C.
Stretching became possible when the temperature was raised to 0 ° C, and tubular stretching was performed 3.5 times in the vertical direction (TUR) and 4.5 times in the horizontal direction (BUR) while cooling with air at 15 ° C. Next, the film was heat-treated at a temperature of 100 ° C. and a relaxation rate of 10% in length and 30% in width, and both ends of the film were cut off and wound as two films. The final magnification of the film is about 3.0 times vertically,
The width was about 3.8 times. The thickness of the final film is 9μ
m (Experiment No. 3).

In the above Experiment No. 1 to No. Table 1 shows the evaluation results of the film No. 3. In Table 1, the physical properties of the resin used for the Z layer and the physical properties of the full-layer film are shown together. Experiment No. 1 (the film of the present invention) and Experiment No. 1 In comparison with 2 (conventional film), the film of the present invention has a larger film loop stiffness and a value larger than 2.5 mg as compared with the conventional film. Even at 9 μm, it can be used in a linear packaging machine, and the improvement effect is clear.

Also, in Experiment No. 1 (the film of the present invention) and Experiment No. 1 In contrast to 3 (single-layer film), the film of the present invention has a 100% elongation load and can be used in a linear packaging machine because it has a multilayer film structure capable of cold stretching. Further, it can be seen that optical properties and heat sealing properties that cannot be obtained with a single-layer film can be imparted.

The experiment No. The film of Experiment No. 1
The strength is significantly improved as compared with the film of Example No. 2, and as an example, the tear strength in the longitudinal direction (according to JIS P8116, measurement range is 100 g) is the same as that of Experiment No. 2. 2 film is 8
g in Experiment No. 24g for one film
Met.

[0051]

Example 2 and Comparative Example 3 PE used in Example 1 for the Z layer
The same experiment as in Example 1 was repeated except that B1 was changed to PEB2 to PEB14 as shown in Table 2, and a film having a thickness of 9 μm was obtained. (Experiments No. 4 to No. 16). However,
The heat treatment conditions were changed so that the film thickness became 9 μm.

In the above Experiment No. 4-No. Table 2 shows the evaluation results of the 16 films. FIG. 1 is an analysis diagram of the present invention. The ordinate represents the flexural modulus of the terpolymer composition, and the abscissa represents the melting point of the terpolymer. The experimental results shown in Tables 1 and 2 (packing suitability, heat sealing) And optical properties) are plotted in relation to the physical properties of the terpolymer composition used. The symbol “◎” indicates that the overall evaluation was “◎”, the symbol “○” indicates that the overall evaluation was “○”, and the symbol “×” indicates that the overall evaluation was “△”
And what was "x".

As is clear from FIG.
Area that satisfies all of the properties and optical characteristics can be separated by lines.
You can see that Point A (120, 45) and point B (14
The area below the straight line that connects
This is an area where packaging is inferior and packaging suitability is poor. Experiment No.
12 and Experiment Nos. 13 is a terpolymer set used for the Z layer
The flexural modulus of the product is 45 kg / mm ^TwoFor smaller
Lm's LS is less than 2.5 mg, resulting in
Conveyance trouble occurred.

The points B (145, 45) and C (14
The area on the right side of the straight line connecting (5, 100) is an area inferior in heat sealability. Experiment No. 15 and Experiment Nos.
No. 16 has a melting point of 145 ° C. of the terpolymer composition using the Z layer.
Therefore, the difference from the upper limit temperature at which heat sealing was possible was less than 5 ° C. Next, point A (120, 45)
The region above the straight line connecting the point C and the point C (145, 100) is a region having poor optical characteristics. Experiment No. The polymer serving as the skeleton of the terpolymer composition used for the Z layer of No. 14 was a block copolymer of ethylene and propylene, and the composition itself was milky white, and thus the optical characteristics of the film were poor.

From the above, the area surrounded by the straight line connecting the coordinate points A, B, and C indicates the suitability of the film for packaging, the optical characteristics,
It can be seen that a region satisfying all the heat sealing properties is shown. Further, point D (127, 60) and point E (135, 6)
0), the area surrounded by the point F (135, 78) is the area where the overall evaluation is “◎”, and is preferable because it has further enhanced film characteristics.

[0056]

Example 3 PEB1 used in Example 1 for the Z layer
Was changed to PEB3, the raw fabric thickness was 30 μm, the heating temperature was 35 ° C., the stretching ratio was TUR = 2.5 times, and the BUR was
The film was stretched at 3.5 times and heat-treated at 70 ° C. to obtain a film having a thickness of 9 μm (Experiment No. 17).

[0057]

Comparative Example 4 Experiment No. 17 film at 100 ° C
For 30 minutes to obtain a film having a thickness of 9 μm (Experiment No. 18).

[0058]

Example 4 PEB1 used in Example 1 for the Z layer
Was replaced with PEB11, and the same experiment as in Example 1 was repeated except that the raw fabric thickness was 90 μm and the relaxation rate during the heat treatment was 0% in height and 10% in width, to obtain a film having a thickness of 9 μm (experiment). No. 19).

[0059]

Comparative Example 5 The same experiment as in Example 4 was repeated except that the heat treatment was not performed in Example 4, and a heat treatment was performed at a temperature of ° C. to obtain a film having a thickness of 9 μm (Experiment N).
o. 20). In the above Experiment No. 17-No. Table 3 shows the evaluation results of the No. 20 films.

Experiment No. 17 and Experiment No. In comparison with No. 18, it is understood that if the 100% elongation load is not 100 g / cm width or more, the suitability for packaging is inferior. Experiment No. 18
Although there is little trouble in transporting the film in the packaging machine, there is a problem that wrinkles are not removed even when the film is stretched. In addition, the optical characteristics, which are features of cold stretching, were poor.
Next, in Experiment Nos. 17 and Experiment No. In comparison with No. 18, if the 100% elongation load is not 600 g / cm width or less, the suitability for packaging is poor. Experiment No. The film of Experiment No. 20 had a large elongation load and was inferior in stretchability. Under the same packaging conditions as in No. 19 (the film of the present invention), there was a problem that the tray was crushed, and wrinkles remained if the tension conditions were weakened so that the tray would not be crushed.

[0061]

Fifth Embodiment In the first embodiment, the thickness of the raw material is set to 30 μm.
The same experiment as in Example 1 was repeated except that the film thickness was changed to a film having a thickness of 7 μm (Experiment No. 21). The physical properties of this film are as follows: LS: 2.5 g, shrinkage at 80 ° C .: 4
0%, 100 elongation load is 280 g / cm width in the vertical direction and 80 g / cm width in the horizontal direction (average of 180 in the vertical direction and the horizontal direction).
g / cm width), the evaluation results were packaging suitability “○”, optical characteristics “◎”, heat sealability “◎”, anti-fogging property “○”, and the overall evaluation was “○”.

Experiment No. Although the film No. 21 is as thin as 7 μm, it can be used in a linear wrapping machine, and the effect of the present invention is remarkable considering that a conventional film tends to cause a problem even with a linear wrapping machine at 10 μm. It is clear that When the thickness was reduced from 9 μm (Experiment No. 1) to 7 μm (Experiment No. 21), the heat sealing property was improved. In particular, the evaluation of the heat sealability of the present invention is performed with a heating time of 2 seconds.
The effect was remarkable when shortened to seconds. In particular,
In the measurement at 1 second, the experiment No. T1 (lower seal temperature) = 140 ° C., T2 (upper seal temperature) =
At 150 ° C., ΔT = 10 ° C. The film No. 21 has T1 = 130 ° C., T2 = 155 ° C. and ΔT = 2
It was recognized that the temperature was greatly improved to 5 ° C.

[0063]

EXAMPLE 6 As a layer X, a composition prepared by blending 25% by weight of EVA, 15% by weight of IPP, 5% by weight of PB-1, 5% by weight of TPO, and 50% by weight of VL1 was used as an antifog agent. A layer to which 2.0% by weight of a 1: 1 mixture of glycerin laurate and glycerin oleate was added, a Y layer, a composition layer in which 75% by weight of IPP and 25% by weight of PB-1 were blended, As a layer, a layer obtained by adding 1.0% by weight of a 1: 1 mixture of diglycerin laurate and glycerin oleate as an antifogging agent to PEB1 was used, and each layer was Z / X / Y / X / Z (= 10% /32.5%/15
% / 32.5% / 10%) in a circular multilayer die (lip diameter: 200 mm, heated to 210 ° C. in a five-layer structure)
Extrusion from lip opening: 0.8 mm (total extrusion: 15)
kg / hour), and the extruded laminate was rapidly cooled with cold water at 15 ° C. and folded to obtain a raw material having a thickness of 80 μm. here,
An aqueous solution of sodium linear alkyl (C ₁₂ ) benzenesulfonate was applied to the inner surface of the raw tube (effective component: about 5%).
mg / m ² ). Air is injected into the folded web to form a tube, heated to 60 ° C, and cooled by air at 15 ° C, 3.5 times in the vertical direction (TUR), and in the horizontal direction (BUR).
After the tube was stretched by a factor of 4.2, it was folded by a roll-type deflator having an opening of 45 °, and was taken up by a take-off roll having a speed ratio of the deflator to the main pinch roll of 0.90. Next, at a temperature of 80 ° C. and a relaxation rate of 10
%, And the film was heat-treated at 30% width, and both ends of the film were cut off and wound as two films. The final magnification of the film is
The height was about 3.1 times and the width was about 2.9 times. The thickness of the final film was 9 μm (Experiment No. 22).

The physical properties of this film were such that LS was 4.0 m.
g, the shrinkage at 80 ° C. is 25%, and the 100 elongation load is 800 g / cm width and 250 g / cm width in the vertical and horizontal directions, respectively, and all of the suitability for packaging, optical properties, heat sealing properties, and anti-fog properties Was “”, and the overall evaluation was also “」 ”.
In particular, this film has excellent impact strength and dart strength (AS
Taking the example of Experiment No. 2
(Conventional film): 12 kg · cm; 1
(Example 1) was 16 kg · cm, whereas experiment N
o. The film of No. 22 was 38 kg · cm, and a remarkable effect was observed.

[0065]

[Table 1]

[0066]

[Table 2]

[0067]

[Table 3]

[0068]

According to the present invention, the conventional polyolefin resin multilayer film obtained by the conventional cold stretching method has excellent conventional properties such as anti-fogging property and strength, particularly, "moderate elongation load at specific elongation ( (100% elongation load is 100-600 g / cm width on average in the longitudinal and transverse directions). High elongation at break = stretchability ”and optical properties are maintained. Value 2.5
mg or more = stiffness ", so that a film which can be heat-sealed without any packaging trouble especially in a linear packaging machine can be obtained.

It is needless to say that the film of the present invention is suitable not only for packaging with a linear packaging machine but also for packaging with a top-up packaging machine and hand packaging.

[Brief description of the drawings]

FIG. 1 is an analysis diagram for obtaining a range of the present invention.

FIG. 2 is a conceptual diagram of a step of continuously packing trays by a linear packing machine.

[Explanation of symbols]

 (1) Film roll (2), (3), (4) Film (5) Edge of film (6), (9) Front ear (8) Rear ear (11), (12), (13), ( 14) Tray (21) Pull-out belt (22) Bag-making plate (23) Center sealer (24) Folding plate (25) Cutter (26) Fold roller (27) Rear ear nozzle (28) Front ear nozzle (29) ) Shutter (30) Chute conveyor (31) Heater

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location B29K 23:00 B29L 9:00

Claims (1)

[Claims] 1. Both surface layers (Z layer) and a stretching auxiliary layer (X layer)
And at least four layers of a core layer (Y layer),
% Elongation load is 100-600g on average in the vertical and horizontal directions
/ Cm width, wherein the both surface layers (Z layers) are a copolymer composition comprising propylene, ethylene and at least one α-olefin having 4 to 8 carbon atoms, and The ordinate indicates the elastic modulus (kg / mm ² ), and the abscissa indicates the melting point (° C.) of the copolymer composition.
Assuming the rectangular coordinates (x, y) shown by, the coordinate point A (1
20, 45), B (145, 45), C (145, 10)
A polyolefin-based resin multilayer stretch film comprising a copolymer composition in a range connecting the three points 0) with straight lines.