JP2001131302A - Film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a multilayered film having heat-sealing strength balanced with easy peelability and containing little solvent-extractables. SOLUTION: This film is a layered product having the surface layer and the reinforcing layer and comprising (A) an ethylene/vinylester, (B) a polyolefin and (C) a tackifier, The component (A) includes 3-20 wt.% vinylester and is included in the layered product at a ratio of 40-75 wt.%, the component (B) is polyethylene and/or an ethylene/α-olefin copolymer and is included in the layered product at a ratio of 15-40 wt.% and the component (C) is represented by hydrocarbon-based resins and is included in the layered product at a ratio of 5-20 wt.%. The layered film can be a two-layer film of surface layer/ reinforcing layer or a three-layer film of surface layer/reinforcing layer/surface layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ethylene / vinyl ester copolymer-based film, and more particularly to an ethylene / vinyl ester copolymer-based multilayer film for packaging applications which has a good balance between heat seal strength and easy peelability. It is about.

[0002]

2. Description of the Related Art Jelly, milk, yogurt, pudding,
As food packaging such as tofu and lactic acid beverages, blister packaging, and other daily necessities and miscellaneous goods, many forms of bottles, cups, or tray-shaped plastic containers covered with a plastic laminated film or aluminum foil laminated film are used. I have. What is required in this packaging form is mechanical strength that can withstand the distribution channel, hygiene retention, and good openability during use.

[0003] As one of the materials used for such packaging, a kind of film called an easy-peelable film is widely used as a lid material. However, the conventional films have high heat seal strength for sealing, but do not always have easy peelability at the time of opening, and a proper balance between them is required. Here, the easy peelability is not only the ease of opening, but also after the opening, there is no residue of adhesion of resin fragments due to the stringing phenomenon in the opening after opening, and the comprehensive evaluation including the good appearance of the opening, Its pass / fail has been determined.

[0004] When the film is used for food packaging, especially when it is used for oily foods,
Since there is a restriction on the use depending on the amount of solvent extraction, it is also required to minimize the amount of solvent extraction as much as possible.
If the contact area between the food and the packaging material is reduced in the design stage of the packaging shape, the amount of extraction is naturally reduced, but basically, a packaging material with a small amount of extraction is also used.

[0005] Conventional easy-peeling films mainly use an ethylene-vinyl acetate copolymer film in consideration of heat seal strength and easy-peeling property. In addition, there is a demand for a film having a small amount of solvent extraction.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a film excellent in packaging suitability, not only good packaging properties, but also a balance between heat seal strength and easy peelability, It is intended to provide a multilayer film with a small amount of extraction.

[0007]

That is, the present invention comprises an ethylene / vinyl ester copolymer (A), a polyolefin (B) and a tackifier (C), and (a) an ethylene / vinyl ester copolymer. The polymer (A) has a vinyl ester content of 3 to 20% by weight, and
(B) polyolefin (B)
Is a polyethylene and / or ethylene / α-olefin copolymer, which is contained in a total amount of 15 to 40% by weight, and (c) a tackifier (C) is a total of 5 to 20%.
% By weight.

The present invention also relates to a laminate comprising a surface layer and a reinforcing layer, wherein the laminate comprises an ethylene / vinyl ester copolymer (A), a polyolefin (B) and a tackifier (C). ) And at least
(A) The ethylene / vinyl ester copolymer (A) has a vinyl ester content of 3 to 20% by weight and is contained in the laminate at 40 to 75% by weight, and (b) a polyolefin (B). Is polyethylene and / or an ethylene / α-olefin copolymer, and 15 to
(C) a tackifier (C)
Relates to a multilayer film containing 5 to 20% by weight in a laminate.

The preferred shape of the laminate is a two-layer film comprising a surface layer and a reinforcing layer,
It may be a three-layer film having a structure of a reinforcing layer / a surface layer, or may be a film of three or more layers.

The surface layer comprises 30 to 50% by weight of an ethylene / vinyl ester copolymer (A), 30 to 50% by weight of a polyolefin (B), and a tackifier (C).
Is preferably a resin composition containing 15 to 30% by weight, and the reinforcing layer comprises 40 to 85% by weight of the ethylene / vinyl ester copolymer (A) and 1% of the polyolefin (B).
0 to 35% by weight, and 5 to 25% of the tackifier (C).
It is preferable that the composition contains about 10% by weight.

[0011]

According to DETAILED DESCRIPTION OF THE INVENTION The full I le arm present invention films, ethylene-vinyl ester copolymer (A), there polyolefin (B) and tackifier and (C) with a film containing at least . This film may be a single-layer film composed of these components or a multilayer film described later.

Each component is uniformly mixed in the film at the following ratio. (A) The ethylene / vinyl ester copolymer (A) has a vinyl ester content of 3 to 20% by weight and is contained in a total of 40 to 75% by weight. (B) Polyolefin (B) is polyethylene and / or
Alternatively, it is an ethylene / α-olefin copolymer, which is contained in a total amount of 15 to 40% by weight. (C) The tackifier (C) is contained in a total amount of 5 to 20% by weight.

The film having such a composition has high mechanical strength and heat seal strength, is excellent in transparency, and has a small amount of solvent extracted, so that it can be used as a packaging film.

[0014] The multilayer film according to the structure present invention the product layer body has a two-layer structure or multilayer structure comprising the at least the surface layer and the reinforcing layer. Specifically, a two-layer film having a structure of a surface layer / reinforcement layer, a three-layer film having a structure of a surface layer / reinforcement layer / surface layer, and a film of three or more layers obtained by adding another layer to these laminates Is mentioned.

What can be said in common to the laminated body is that at least one surface layer can be used as, for example, a heat seal surface to a plastic container, and is a layer in which a balance between heat seal strength and easy peelability is required. is there. The other surface layer of the multilayer film having three or more layers can be used, for example, as a laminated surface to another lid material. The reinforcing layer is a layer provided mainly for the purpose of increasing the mechanical strength of the film, but actually has an effect of reducing the amount of solvent extracted from the multilayer film. The reinforcing layer is not necessarily limited to one layer, and may be formed in two or more layers having different compositions, and a resin layer made of only polyolefin may be laminated outside the reinforcing layer.

The thickness of the multilayer film is 20 to 50, preferably 20 to 40, more preferably 20 to 30 μm.
If the thickness is within this range, the film can be used as a packaging film having flexibility and high mechanical strength.

In the case of a two-layer film, the thickness ratio (%) between the surface layer and the reinforcing layer is (surface layer 10 to 85) :( reinforcement). Layers 15-9
0), preferably (surface layers 20 to 85): (reinforcing layer 15)
~ 80). In the case of a three-layer film, (surface layer 1
0-70): (Reinforcing layers 10-80): (Surface layers 10-7)
0), preferably (surface layers 20 to 80): (reinforcing layer 20)
To 70): (surface layers 20 to 80). When the thickness ratio of each layer is within this range, it is possible to form a surface layer having a good balance between heat seal strength and easy peelability, and a reinforcing layer having high mechanical strength. The amount of extraction can be reduced.

Structural Materials The resin constituting the laminate includes at least an ethylene / vinyl ester copolymer (A), a polyolefin (B), and a tackifier (C). The ethylene-vinyl ester copolymer (A) occupying 4 parts of the entire laminate is
0 to 75, preferably 48 to 70% by weight; the polyolefin (B) 15 to 40, preferably 20 to 35% by weight;
The tackifier (C) is 5 to 20, preferably 8 or more and less than 20, and more preferably 10 to 17% by weight. here,
The total amount of (A), (B) and (C) is 100% by weight
It has become. When within this composition range, a well-balanced heat seal strength and easy peelability are imparted to the multilayer film, the amount of solvent extraction is reduced, and the film is formed into a stiff film, and is excellent in various packaging suitability. ing.

Ethylene / vinyl ester copolymer (A)
Is a copolymer of ethylene and a vinyl ester such as vinyl acetate or vinyl propionate, wherein the vinyl ester content in the copolymer is in the range of 3 to 20% by weight. When the vinyl ester content is within this range, the balance between heat seal strength and easy peelability is kept good, and the composition has the heat resistance required for filling foods, which is advantageous. In addition, the melt flow rate (MFR) of this copolymer is 1 to 40, preferably 1.5 to 30 (g / 10 minutes) as measured according to JIS 6730.
Is desirable for obtaining good extrudability and high mechanical strength.

The polyolefin (B) is a polyethylene and / or an ethylene / α-olefin copolymer, one of which may be used alone, or a combination of two or more thereof. You may mix and use. The polyolefin (B) has an effect of imparting heat resistance to the resin composition and making the multilayer film resistant to high temperatures during packaging.

Examples of polyethylene include high-pressure low-density polyethylene, medium-low pressure medium-high-density polyethylene, and linear low-density polyethylene (LL) produced with a Ziegler catalyst.
DPE) and linear low-density polyethylene (L-LDPE) produced with a metallocene catalyst.
Its melt flow rate (MFR) is ASTM D-
The value measured at 190 ° C. under a load of 2.16 kg is 0.5 to 20, preferably 1 to 10 (g /
10 minutes).

The ethylene / α-olefin copolymer is prepared by mixing ethylene with 5 to 50, preferably 8 to 40 mol% of α-olefin.
It is a copolymer with olefin. Examples of α-olefins include propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene,
Examples thereof include α-olefins having 3 to 20 carbon atoms such as 1-decene, and these α-olefins may be used alone or in combination of two or more.
Among them, propylene, 1-butene, 1-hexene, 1-
Octene is preferred. This copolymer is an amorphous or low-crystalline polymer having a density of 0.85 to 0.90.
(G / cm ³ ), and the melt flow rate (MFR) measured at 190 ° C. under a load of 2.16 kg according to ASTM D-1238 is 0.2 to 30 (g / 10 minutes). preferable.

As the tackifier (C), general tackifiers blended with plastics and rubbers can be used.
For example, aliphatic, alicyclic, or aromatic hydrocarbon-based resins, terpene-based resins, rosin-based resins, styrene-based resins, and the like can be given, and among them, hydrocarbon-based resins are particularly preferable. By blending these tackifiers, high heat sealing strength can be imparted to the resin composition.

If necessary, additives such as an antioxidant, a weather stabilizer and an antistatic agent can be added to the resin within a range not deviating from the object of the present invention. In particular,
By blending an anti-blocking agent and a slip agent, workability and workability during extrusion, lamination, packaging, and the like can be improved.

As the anti-blocking agent, silica,
Examples include inorganic powders such as talc, clay, and zeolite. As slip agents, fatty acid amides such as stearic acid amide, oleic acid amide, palmitic acid amide, erucic acid amide; stearic acid, oleic acid,
Fatty acid bisamides such as methylene bisamide and ethylene bisamide of fatty acids such as erucic acid; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; hydrogenated castor oil; fatty acid metal salts; These anti-blocking agents and slip agents are preferably blended in the resin in an amount of 1000 to 2000 ppm.

The resin composition of each layer The materials constituting the surface layer and the reinforcing layer are ethylene / vinyl ester copolymer (A), polyolefin (B),
The tackifier (C) and, if necessary, an antiblocking agent, a slip agent, and other additives are blended to form a resin composition, which is then subjected to film forming.

As the resin constituting the surface layer, the ethylene / vinyl ester copolymer (A) is 30 to 50, preferably 3 to 50.
5 to 45% by weight, polyolefin (B) is 30 to 50,
Preferably 35 to 45% by weight, 15 to 3 tackifiers
0, preferably 17 to 25% by weight. When each component is within this range, the balance between heat seal strength and easy peelability can be maintained, and the amount of solvent extraction can be minimized. You can control.

The resin constituting the reinforcing layer contains 40 to 85, preferably 50 to 80% by weight of the ethylene / vinyl ester copolymer (A) and 10 to 3% by weight of the polyolefin (B).
5, preferably 12 to 30% by weight, and the tackifier is 5 to 5%.
25, preferably 7 to 20% by weight. When the content is within this range, a layer having excellent mechanical strength and heat resistance can be formed. When the reinforcing layer is composed of two or more layers, it is preferable to change the composition of each layer within the range of the resin composition.

On the other hand, the content of the vinyl ester in the ethylene / vinyl ester copolymer (A) used in the laminate is in the range of 3 to 20% by weight as described above. It is also possible to prepare the above ethylene / vinyl ester copolymers and use different ethylene / vinyl ester copolymers for the surface layer and the reinforcing layer by utilizing the difference in their properties. For example, using an ethylene / vinyl ester copolymer with a low vinyl ester content for the surface layer, the balance between heat seal strength and easy peelability is further improved, and an ethylene / vinyl ester copolymer with a high vinyl ester content is used as a reinforcing layer. To give a film with a smaller amount of solvent extraction as a whole of the laminate. In addition, a layer mainly containing an ethylene / vinyl ester copolymer having a low vinyl ester content is arranged on the surface layer, and the ethylene / vinyl ester content having a high vinyl ester content increases as the distance from the surface layer increases.
It is preferable to laminate a layer mainly containing a vinyl ester copolymer, because it is easy to achieve a balance between heat sealability and easy peelability, and it is easy to achieve high mechanical strength and a small amount of solvent extraction. .

The melt flow rate (MFR) of each resin composition forming the surface layer and the reinforcing layer is JIS 673.
The value measured according to 0 is 1 to 40, preferably 1.5
It is preferable that it is in the range of from 30 to 30 (g / 10 minutes) in order to improve the extrudability and obtain high mechanical strength. In particular,
The density of the resin composition forming the surface layer is higher than the density and the MFR of the resin composition forming the reinforcing layer, and the MF
When R is small, the stiffness of the multilayer film is increased, and the film formability is improved.

The anti-blocking agent and the slip agent may be added to either or both of the surface layer and the reinforcing layer, but a higher anti-blocking effect can be obtained by adding the anti-blocking agent and the slip agent only to the surface layer. that time,
The compounding amount in the surface layer may be smaller than the compounding amount in a normal single-layer film,
5000 ppm, slip agent 1000-2000 pp
It is sufficient to mix m, which is one feature of the present invention. As a result, it is possible to reduce the amount of blemishes adhered to the molding machine die and to reduce the dirt on the cooling roll, which is preferable for molding work, and to obtain a highly transparent film by reducing the compounding amount. Can be.

Such a resin composition is uniformly mixed by using a mixer such as a Henschel mixer, an extruder, a Banbury mixer, a kneader, a pravender and the like, and if necessary, a kneading operation is added to obtain a more uniform composition. Can be obtained.

The multilayer film can be formed by preparing a film for forming the surface layer and a film for forming the reinforcing layer separately in advance, and then forming a laminate by dry lamination. A laminate can also be produced by extruding a resin composition for forming a surface layer on a film for forming a layer by extrusion lamination. Or,
A laminate can also be produced by extruding a resin composition for forming a reinforcing layer on a film for forming a surface layer formed in advance.

A more preferred method of forming a multilayer film is a method in which the surface layer and the reinforcing layer are formed at once by a co-extrusion method as a co-extruded film. That is, a resin composition for forming a surface layer and a resin composition for forming a reinforcing layer are supplied to separate extruders, respectively, and both molten resins are fed from a co-extrusion die attached to the tip of a T-die or inflation type film forming machine. This is a method in which the composition is extruded as a laminate of two or more layers, cooled and taken off.

The multilayer film thus produced can be used as various packaging films for foods, medicines, medical instruments and the like. In particular, it can be suitably used as a lid material for rigid food packaging containers such as bottles, cups and trays formed of polystyrene, polyethylene, polypropylene, polyamide, polyester resin, vinyl chloride resin and the like. At this time, the surface layer side of the multilayer film is bonded to the periphery of the opening of the container by heat sealing to seal the container. Due to packaging requirements or usage requirements, a metal layer such as aluminum foil or another resin layer may be laminated outside the reinforcing layer of the multilayer film, and in some cases, outside the other surface layer. it can.

[0036]

Next, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

The raw materials used in this example are as follows. (1) Ethylene-vinyl acetate copolymer (EVA-1): 10% by weight of vinyl acetate (2) Ethylene-vinyl acetate copolymer (EVA-2): Product (trade name) of Mitsui-DuPont Polychemical Co., Ltd. P-1
405C) vinyl acetate content 14% by weight, density 0.93 (g / c
m ³ ) MFR 3.5 (g / 10 min), melting point 90 ° C. (3) Ethylene-vinyl acetate copolymer (EVA-3): a product of Mitsui-Dupont Polychemical Co., Ltd. (trade name V-5)
714) Vinyl acetate content 16% by weight, MFR 3.0 (g / 10
Minutes)

(4) Ethylene / 1-butene copolymer (EBR): product of Mitsui Chemicals, Inc. (trade name: Tuffmer) 1-butene content 10% by weight, density 0.88 (g / c)
m ³ ) MFR 4.0 (g / 10 min) (5) Aliphatic hydrocarbon resin (C): Arakawa Chemical Co., Ltd. product (product name: Alcon) Ring and ball method softening point 115 ° C (6) Erucamide: Japan Oil & Fats Co., Ltd. product (trade name: Alflo P-10) Higher fatty acid monoamide type lubricant Melting point: 78 to 85 ° C. (7) Silica: Manville, USA (trade name: Celite; Sparfloss) Natural inorganic additive Average particle size: 2 to 4 μm

Next, four types of resin compositions (D), (E), (F) and (G) were produced using the above-mentioned raw materials.
Table 1 shows the composition and physical properties of each resin composition.

[Table 1]

(Examples 1 to 4) (Comparative Example 2) The resin compositions (D), (F) and (G) described in Table 1 were dry-blended at the ratios shown in Table 2 as the surface layer forming resin. On the other hand, the resin compositions (D) and (E) were dry-blended at the ratios shown in Table 2 and used as the reinforcing layer forming resin. Each resin was supplied to a separate extruder, and a three-layer coextruded film having a structure of surface layer / reinforcement layer / surface layer was obtained by a T-die method. The total thickness of the film is 30μ
m, and the thickness ratio was surface layer: reinforcement layer: surface layer = 2: 6: 2. The physical properties of the obtained film were measured, and the results are shown in Table 3.

(Examples 5 to 8) (Comparative Example 3) The resin compositions (D), (F) and (G) described in Table 1 were dry-blended in the proportions shown in Table 2 as the surface layer forming resin. On the other hand, the resin compositions (D) and (E) were dry-blended at the ratios shown in Table 2 and used as the reinforcing layer forming resin. Each resin was supplied to a separate extruder, and a two-layer co-extruded film having a constitution of a surface layer / a reinforcing layer was obtained by a T-die method. The total thickness of the film was 30 μm, and the thickness ratio was surface layer: reinforcing layer = 2: 6. The physical properties of the obtained film were measured, and the results are shown in Table 3.

(Comparative Example 1) The resin compositions (D), (F) and (G) were dry-blended at the ratios shown in Table 2 and then supplied to an extruder. A layer film was formed. The physical properties of the obtained film were measured, and the results are shown in Table 3.

The test method is as follows. (1) Heat sealability: A stretched polyethylene terephthalate film (PET) having a thickness of 12 μm and a film obtained in each of the examples and comparative examples were laminated to have a thickness of 20 mm.
A laminate was manufactured by extrusion lamination using a high-pressure low-density polyethylene of μm. In addition, the film surface obtained in each Example and Comparative Example was used as the surface layer side.

Using a heat sealer, the surface layer side of the laminate and a polypropylene sheet (PP) having a thickness of 300 μm
Alternatively, a polystyrene sheet (PS) having a thickness of 300 μm was heat-sealed, and the sealing strength was measured. In addition,
The sealing conditions were as follows: the temperature was changed to three points of 160, 180, and 200 ° C., and the pressure was set to 0.2 MPa and the time was set to 1 second.

As a result, the heat sealability was determined as follows. A: Sufficient sealing strength was obtained, and the peeled surface was also clean. ：: The seal strength was within the allowable range, but slightly smaller, and the peeled surface was clean. Δ: The seal strength was low, and stringing was partially caused by delamination. X: The seal strength was small and varied, and many stringings due to layer peeling occurred.

(2) Solvent extractability: Requested by an external public organization, "3rd equipment and standard for foods and additives, etc. 3 ". The working temperature was 100 ° C. or less, and the surface layer (heat-sealed surface) was subjected to a one-side extraction method. In addition, the residual amount of evaporation in the dissolution test was shown in ppm.

(3) Haze: According to JIS 7105, haze was measured using a direct-read type haze meter manufactured by Toyo Seisakusho in a state where four films were stacked. (4) Slip property: Using a tilt type slip measuring device,
The sliding property between the surface layers was measured. (5) Yield point strength:
According to JIS 7127, the longitudinal direction of the film (M
The strength of D) was measured.

(6) Processability: The amount of blemishes generated during film formation is determined by the amount of light brown to brown T-die deposits and the presence or absence of streaks on the film surface caused by the blemishes. Was evaluated. ：: No streaks were formed on the eyes. ：: Slightly found in eyes and eyes, but no streaks were found. Δ: Eyes and spots were partially scattered in light brown, and thin streaks were generated at the spots. X: The eyes and limbs were partially browned, and the occurrence of streaks could be clearly confirmed at that location. Further, the degree of contamination of the casting roll for cooling the molten resin extruded from the T-die was compared, and the roll contamination was evaluated. A: Almost no dirt. ：: Slight dirt was slightly observed. Δ: White stains of practically no problem. X: White and dirty.

[0049]

[Table 2]

[0050]

[Table 3]

[0051]

The film according to the present invention can be used as a packaging film because of its high mechanical strength and heat seal strength, excellent transparency, and low solvent extraction.

In the multilayer film according to the present invention, the ethylene / vinyl ester copolymer (A), the polyolefin (B), and the tackifier (C) constituting the laminate are mixed at a specific ratio. Since the composition has a high heat seal strength, it also satisfies mutually contradictory physical properties of maintaining high heat seal strength and also maintaining easy peelability. In addition, since this multilayer film contains polyolefin (B) in addition to ethylene-vinyl ester copolymer (A), it has heat resistance, can withstand heating during packaging, and can be filled at high temperature. Can be prevented from being damaged from the heat seal portion.

Furthermore, regarding the transfer of the oil-soluble substance from the film components assuming that the film comes into contact with oily foods, the amount of solvent extracted from the multilayer film could be reduced, so that hygiene could be maintained. . Therefore, this multilayer film can be suitably used as a container lid for oily and fatty foods.

Furthermore, by adding a small amount of an antiblocking agent and a slipping agent to the surface layer, the blocking of the film can be sufficiently prevented. And the contamination of the cooling roll can be reduced.
Also, when the multilayer film is laminated with another material, roll contamination of the processing machine can be reduced. Therefore, this multilayer film can be formed into a film having high molding workability and high transparency.

Front page of the continued F-term (reference) 4F071 AA15 AA15X AA16 AA17 AA18 AA19 AA20X AA21X AA22 AA28X AA74 AA82 AA88 AE22 AH04 AH05 BC02 BC12 4F100 AJ02H AK02H AK03A AK03B AK03C AK04A AK04B AK04C AK11H AK12H AK62A AK62B AK62C AK64A AK64B AK64C AK65A AK65B AK65C AK68A AK68B AK68C AL05A AL05B AL05C BA02 BA03 BA16 CA16A CA16B CA16C GB18 GB23 JA20A JA20B JA20C JJ03 JK06 JL12 JL14 YY00A YY00B YY00C 4J002 AA003 AF023 BA003 BB032 BB052 BB152 BC021 BF011 BF031

Claims (10)

[Claims] 1. An ethylene / vinyl ester copolymer (A), a polyolefin (B) and a tackifier (C), wherein (a) the ethylene / vinyl ester copolymer (A) The ester content is 3 to 20% by weight, and the total content is 40 to 75% by weight. (B) Polyolefin (B) is polyethylene and / or
Or an ethylene / α-olefin copolymer containing 15 to 40% by weight as a whole, and (c) the tackifier (C) being 5 to 20% by weight as a whole. Characteristic film. 2. A laminate comprising a surface layer and a reinforcing layer, wherein materials constituting the laminate include an ethylene / vinyl ester copolymer (A), a polyolefin (B) and a tackifier (C). And (a) the ethylene-vinyl ester copolymer (A) has a vinyl ester content of 3 to 20% by weight and is contained in the laminate at 40 to 75% by weight. (B) the polyolefin (B) is polyethylene and / or
Or an ethylene / α-olefin copolymer, which is contained in the laminate at 15 to 40% by weight, and (c) the tackifier (C) is contained at 5 to 20% by weight in the laminate. A multilayer film characterized by the following. 3. The multilayer film according to claim 2, wherein the laminate is a two-layer film including a surface layer and a reinforcing layer. 4. The two-layer film has a thickness of 20 to 50 μm.
m, and the thickness ratio (%) between the surface layer and the reinforcing layer is (10 to 10).
85): The multilayer film according to claim 3, wherein (15 to 90). 5. The multilayer film according to claim 2, wherein said laminate is a three-layer film comprising a surface layer / a reinforcing layer / a surface layer. 6. The thickness of the three-layer film is 20 to 50 μm.
m, and the thickness ratio (%) of each layer is (surface layers 10 to 7).
0): (reinforcing layers 10 to 80): (surface layers 10 to 70). 7. The ethylene / α-olefin copolymer is ethylene / propylene copolymer or ethylene / 1
-A butene copolymer.
The multilayer film according to any one of the above. 8. The method according to claim 1, wherein the tackifier (C) is an aliphatic compound,
The resin is at least one resin selected from the group consisting of alicyclic and aromatic hydrocarbon resins, terpene resins, rosin resins, and styrene resins. The multilayer film according to any one of the above. 9. The surface layer comprises 30 to 50% by weight of an ethylene / vinyl ester copolymer (A), 30 to 50% by weight of a polyolefin (B), and a tackifier (C).
The multilayer film according to any one of claims 2 to 8, wherein 15 to 30% by weight is contained. 10. The reinforcing layer comprises 40 to 85% by weight of the ethylene / vinyl ester copolymer (A), 10 to 35% by weight of the polyolefin (B), and 5 to 35% by weight of the tackifier (C). The multilayer film according to any one of claims 2 to 9, comprising 25% by weight.