JP7537235B2 - Polypropylene multi-layer film, packaging material and package using same - Google Patents

Description

The present invention relates to a multilayer film, a packaging material, and a package. More specifically, the present invention relates to a polypropylene-based multilayer film that has excellent heat resistance, transparency, and cold impact resistance, and can be suitably used as a sealant film for packaging bags, even in harsh treatments such as boiling water treatment and retort treatment, and to a packaging material and a package obtained using the polypropylene-based multilayer film.

Polypropylene films are sometimes used as sealant films in various packaging materials, such as food packaging, because they have excellent rigidity and heat resistance and are inexpensive.

Generally, propylene-ethylene block copolymers used in retort packaging bags contain and disperse elastomer components to improve the impact resistance of propylene resin at low temperatures. However, the shape of the dispersed elastomer components creates unevenness on the film surface, which causes diffuse reflection of light and increases external haze, resulting in an essentially opaque film.

In recent years, in addition to the above-mentioned properties, retort packaging bags have also come to be required to be transparent so that the packaged contents can be seen. For example, the following patent document describes a film with improved transparency.

Patent Document 1 proposes a three-layer polypropylene composite film, characterized in that the middle layer is made of a propylene-ethylene block copolymer and both surface layers are made of a propylene random copolymer. However, the propylene random copolymer of the surface layer has insufficient heat resistance, and high retort processing, which involves pressure processing at high temperatures of 135°C or higher, causes problems such as deformation of the film and fusion on the inner surface of the packaging bag.

Patent Document 2 proposes a multilayer film consisting of two surface layers made of a propylene homopolymer or a propylene-based random copolymer and an ethylene-α-olefin copolymer, and an intermediate layer made of a propylene-ethylene block copolymer and an ethylene-α-olefin copolymer. However, the addition of an ethylene-α-olefin copolymer to both surface layers causes problems with the heat resistance and heat sealability.

Patent Document 3 proposes a multilayer film consisting of two surface layers made of a propylene homopolymer or a propylene-based random copolymer, and an inner layer made of an ethylene-propylene block copolymer and a polyolefin-based polymer that has good compatibility with the rubber component in the block copolymer. However, using only a propylene homopolymer or only a propylene-based random copolymer in the surface layer results in insufficient cold impact resistance, and there is a problem that the bag breaks after storage at low temperatures.

In recent years, increasingly higher levels of cold impact resistance and heat resistance have been required for polypropylene sealant films used in retort packaging bags, and there is also a growing demand for transparency so that the packaged contents can be seen. However, no configurations disclosed to date have been found that satisfy high levels of heat resistance, cold impact resistance, and transparency.

JP 2017-132186 A JP 2017-105174 A Japanese Unexamined Patent Publication No. 62-3950

Polypropylene-based multilayer films are now required to have heat resistance that can withstand retort processing, in which pressure treatment is performed at high temperatures of, for example, 120 to 135°C to perform sterilization and sterilization, excellent cold impact resistance so that the bag will not break even if it is dropped during low-temperature storage, and transparency that allows the contents to be maintained in a visible state. However, with conventional polypropylene-based films, it is currently difficult to satisfy all of the requirements for excellent heat resistance, cold impact resistance, and transparency.

The present invention has been made in consideration of the above circumstances, and aims to provide a polypropylene-based multilayer film that is capable of achieving both excellent heat resistance, cold impact resistance, and transparency. Another aim of the present invention is to provide a packaging material and a package obtained using the multilayer film.

The multilayer film according to one aspect of the present invention comprises, in this order, a first outer layer containing 75 to 90% by mass of a propylene homopolymer (A) and 10 to 25% by mass of a non-crosslinked olefin-based thermoplastic elastomer (B), an inner layer made of a propylene-ethylene block copolymer (C), and a second outer layer containing 75 to 90% by mass of a propylene homopolymer (A) and 10 to 25% by mass of a non-crosslinked olefin-based thermoplastic elastomer (B).

In the multilayer film, the outer layer contains a propylene homopolymer (A) and a non-crosslinked olefin-based thermoplastic elastomer (B) in a specific ratio. This makes it possible to maintain excellent heat resistance and cold impact resistance while suppressing surface irregularities, which are a factor in reducing the transparency of the film. This effect cannot be obtained when a propylene-based random copolymer is used in the outer layer (for example, Patent Document 1 above), when an ethylene-α-olefin copolymer and a propylene-based polymer are used (for example, Patent Document 2 above), or when a propylene homopolymer or a propylene-based random copolymer is used in the outer layer (for example, Patent Document 3 above), and is an effect that is particularly suitable for retort treatment applications.

In one embodiment, the inner layer may contain 50 to 90% by mass of a propylene-ethylene block copolymer (C) and 10 to 50% by mass of an ethylene-propylene copolymer elastomer (D). This provides the film with low-temperature impact resistance, resulting in excellent cold impact resistance.

In one embodiment, the total thickness of the first outer layer and the second outer layer may be 16 to 42% of the thickness of the multilayer film. This makes it easier to achieve both transparency and cold impact resistance.

In one embodiment, the thickness of the inner layer may be 20 μm or more. This makes it easier to maintain the cold impact resistance of the film.

A packaging material according to one aspect of the present invention comprises the above-mentioned multilayer film and a substrate.

The packaging body according to one aspect of the present invention is made from the above-mentioned packaging material.

According to the present invention, it is possible to provide a polypropylene-based multilayer film that is capable of satisfying all of the requirements of excellent heat resistance, cold impact resistance, and transparency. In addition, according to the present invention, it is possible to provide a packaging material and a package obtained by using the multilayer film.

FIG. 1 is a cross-sectional view of a multilayer film according to one embodiment of the present invention.

<Multilayer film>
Fig. 1 is a cross-sectional view of a multilayer film according to one embodiment of the present invention. The multilayer film 10 includes a first outer layer 1a, an inner layer 2, and a second outer layer 1b in this order. The multilayer film can be used as a polypropylene-based non-stretch sealant film.

[First outer layer and second outer layer]
The first outer layer 1a and the second outer layer 1b contain a propylene homopolymer (A) and a non-crosslinked olefin-based thermoplastic elastomer (B). The first outer layer 1a and the second outer layer 1b may be collectively referred to simply as "outer layers". The first outer layer 1a and the second outer layer 1b may have the same composition or different compositions.

(Propylene homopolymer (A))
The propylene homopolymer (A) can be obtained by homopolymerizing propylene using, for example, a Ziegler-Natta catalyst, a metallocene catalyst, or a half-metallocene catalyst. By including the propylene homopolymer (A) in the outer layer, excellent heat resistance can be imparted to the outer layer.

The propylene homopolymer (A) may be one that has a melting onset temperature of 150°C or higher and a melting peak temperature of 155°C or higher when measured by differential scanning calorimetry (JIS K 7121). A polymer having both a melting onset temperature and a melting peak temperature within this range has excellent heat resistance, and is less likely to fuse on the inner surface of a packaging bag after, for example, a retort treatment at high temperature.

As the propylene homopolymer (A), one having a melt flow rate (MFR: ISO 1133) (temperature 230°C, load 2.16 kg) in the range of 2.0 to 7.0 g/10 min can be used. When the melt flow rate is equal to or higher than the lower limit, the load on the extruder during molding is small, the processing speed is less likely to decrease, and excellent productivity can be easily maintained. In addition, when the melt flow rate is equal to or lower than the upper limit, the outer layer is likely to have excellent impact resistance.

(Non-crosslinked olefin-based thermoplastic elastomer (B))
The non-crosslinked olefin-based thermoplastic elastomer (B) can be obtained by introducing a crystalline polymer, which is a hard segment, and a large amount of a rubber component, which is a soft segment, at the polymerization stage in a gas phase polymerization process using a metallocene catalyst. By containing the non-crosslinked olefin-based thermoplastic elastomer (B) in the outer layer, it is possible to maintain excellent cold impact resistance while imparting excellent transparency.

As the non-crosslinked olefin-based thermoplastic elastomer (B), an ethylene-propylene random copolymer elastomer in which the crystalline polymer, which is the hard segment, is made of propylene and the rubber component, which is the soft segment, is formed by randomly polymerizing ethylene and propylene, can be used.

As the non-crosslinked olefin-based thermoplastic elastomer (B), one having a ratio of propylene content to ethylene content (propylene content/ethylene content) in the range of 2 to 4 can be used. When the above ratio is equal to or greater than the lower limit, the impact resistance of the film is maintained, and excellent cold impact resistance is easily obtained even after retort treatment. When the above ratio is equal to or less than the upper limit, excellent heat resistance is obtained, and, for example, fusion is unlikely to occur on the inner surface of a packaging bag after retort treatment at high temperature.

As the non-crosslinked olefin-based thermoplastic elastomer (B), one having a Vicat softening temperature (500 g load) (JIS K 7206) of 100°C or higher can be used. With a softening temperature of 100°C or higher, the elastomer has excellent heat resistance, and for example, after retort treatment at high temperatures, fusion is unlikely to occur on the inner surface of a packaging bag.

The outer layer contains 75 to 90% by mass of propylene homopolymer (A) and 10 to 25% by mass of non-crosslinked olefin-based thermoplastic elastomer (B). By having a propylene homopolymer (A) content of 75% by mass or more, excellent heat resistance can be maintained. Furthermore, by having a propylene homopolymer (A) content of 90% by mass or less, that is, by having a non-crosslinked olefin-based thermoplastic elastomer (B) content of at least 10% by mass or more, excellent transparency and cold impact resistance can be achieved.

[Inner layer]
The inner layer 2 contains a propylene-ethylene block copolymer (C) and an ethylene-propylene copolymer elastomer (D).

(Propylene-Ethylene Block Copolymer (C))
The propylene-ethylene block copolymer (C) is a copolymer that can be obtained by producing a propylene polymer (C1) in a first step, and then producing an ethylene-propylene copolymer (C2) by gas phase polymerization in a second step. The propylene-ethylene block copolymer (C) is not a block copolymer in which a propylene polymer end and an ethylene-propylene copolymer end are bonded, but is a type of blend copolymer. By containing the propylene-ethylene block copolymer (C) in the inner layer, the flexibility of the film is maintained, and excellent cold impact resistance is easily obtained.

As the propylene-ethylene block copolymer (C), one having a melt flow rate (MFR: ISO 1133) (temperature 230°C, load 2.16 kg) in the range of 0.5 to 2.5 g/10 min can be used. When the melt flow rate is equal to or higher than the lower limit, the load on the extruder during molding is small, the processing speed is less likely to decrease, and excellent productivity can be easily maintained. When the melt flow rate is equal to or lower than the upper limit, the inner layer is likely to have excellent cold impact resistance.

The propylene-ethylene block copolymer (C) may contain 60 to 90% by mass of the above propylene polymer (C1) and 10 to 40% by mass of the ethylene-propylene copolymer (C2). By having each component in this range, it is easy to obtain excellent cold impact resistance.

The ethylene content of the ethylene-propylene copolymer (C2) contained in the propylene-ethylene block copolymer (C) is not particularly limited, but can be in the range of 20 to 40% by mass. By having the ethylene content be equal to or less than the upper limit, the tackiness of the product can be suppressed, and contamination due to the tackiness of the product during production is less likely to occur, making it easier to maintain excellent productivity. By having the ethylene content be equal to or more than the lower limit, the flexibility of the film is maintained, making it easier to obtain excellent cold impact resistance even after retort processing.

(Ethylene-propylene copolymer elastomer (D))
The ethylene-propylene copolymer elastomer (D) can be obtained by, for example, a slurry polymerization method carried out in the presence of an inert hydrocarbon such as hexane, heptane, kerosene, or a liquefied α-olefin solvent such as propylene, or a gas phase polymerization method in the absence of a solvent. Specifically, the ethylene-propylene copolymer elastomer (D) can be obtained by a known multi-stage polymerization method. That is, it is a polymerized type high-rubber-containing polypropylene-based resin obtained by polymerizing propylene and/or propylene-α-olefin polymer in a first-stage reactor and then copolymerizing propylene with an α-olefin in a second-stage reaction. By containing the ethylene-propylene copolymer elastomer (D) in the inner layer, it is easy to impart impact resistance to the film and easy to obtain excellent cold impact resistance.

The ethylene-propylene copolymer elastomer (D) may have a melt flow rate (MFR: ISO 1133) (temperature 230°C, load 2.16 kg) in the range of 0.5 to 3.5 g/10 min. When the melt flow rate is equal to or higher than the lower limit, the load on the extruder during molding is small, the processing speed is unlikely to decrease, and excellent productivity can be easily maintained. When the melt flow rate is equal to or lower than the upper limit, the compatibility between the propylene-ethylene block copolymer (C) and the ethylene-propylene copolymer elastomer (D) is good, and transparency is unlikely to decrease.

As the ethylene-propylene copolymer elastomer (D), one having a ratio of propylene content to ethylene content (propylene content/ethylene content) in the range of 1.5 to 4 can be used. When the above ratio is equal to or greater than the lower limit, the impact resistance of the film is maintained, and excellent cold impact resistance is easily obtained even after retort treatment. When the above ratio is equal to or less than the upper limit, the compatibility between the propylene-ethylene block copolymer (C) and the ethylene-propylene copolymer elastomer (D) is good, and transparency is less likely to decrease.

The inner layer may contain 50 to 90% by mass of propylene-ethylene block copolymer (C) and 10 to 50% by mass of ethylene-propylene copolymer elastomer (D). When the content of propylene-ethylene block copolymer (C) is 50% by mass or more, it is easy to maintain excellent cold impact resistance. Furthermore, when the content of propylene-ethylene block copolymer (C) is 90% by mass or less, that is, when the content of ethylene-propylene copolymer elastomer (D) is at least 10% by mass or more, even more excellent cold impact resistance can be achieved.

There are no particular limitations on the thickness of the multilayer film, so long as it is within a range that allows it to be used as a film for packaging materials, for example, but if the film is too thick, it will have a cost disadvantage. For this reason, the thickness of the multilayer film can be 100 μm or less, and may be 50 to 70 μm.

The thickness of the outer layer (i.e., the total thickness of the first outer layer and the second outer layer) may be 16 to 42% of the thickness of the multilayer film. When the ratio of the thickness of the outer layer is equal to or greater than the lower limit, excellent transparency is easily obtained, and when the ratio is equal to or less than the upper limit, excellent cold impact resistance is easily obtained.

The thickness of the inner layer may be 20 μm or more. This maintains the flexibility of the film, and cold impact resistance is easily achieved even after retort processing. From this perspective, the thickness of the inner layer may be 25 μm or more, or 30 μm or more. There is no particular upper limit to the thickness of the inner layer, but it can be set to 50 μm because of the cost disadvantage.

<Method of manufacturing multi-layer film>
The method for producing the multilayer film is not particularly limited, and known methods can be used. For example, examples of the thermoforming process include a melt-kneading method using a general mixer such as a single-screw extruder, a twin-screw extruder, or a multi-screw extruder, and a method in which the components are dissolved or dispersed and mixed, and then the solvent is removed by heating. In consideration of workability, a single-screw extruder or a twin-screw extruder can be used. When a single-screw extruder is used, the screw can be a full-flight screw, a screw with a mixing element, a barrier flight screw, a fluted screw, or the like, which can be used without any particular restrictions. As the twin-screw kneading device, a co-rotating twin-screw extruder, a counter-rotating twin-screw extruder, or the like can be used, and the screw shape can be a full-flight screw, a kneading disk type, or the like, which can be used without any particular restrictions.

In the above method, it is possible to use a method in which the multilayer film is melted using a single-screw extruder or twin-screw extruder, etc., and then formed into a film using a T-die via a feed block or multi-manifold.

If necessary, the obtained multilayer film may be subjected to a surface modification treatment to improve suitability for subsequent processes. For example, to improve printability when used as a single film or lamination suitability when used in layers, a surface modification treatment may be performed on the printing surface or the surface that comes into contact with the substrate. Examples of surface modification treatments include treatments that generate functional groups by oxidizing the film surface, such as corona discharge treatment, plasma treatment, and frame treatment, and modification treatments using a wet process that forms an easy-adhesion layer by coating.

<Packaging materials>
The multilayer film may be used as a single film or may be laminated with a substrate, and the method of use as a packaging material is not particularly limited.

When the multilayer film is laminated with a substrate, the packaging material can include the multilayer film and the substrate. Specifically, such packaging material can be obtained by laminating at least one layer of a substrate such as a biaxially oriented polyamide film (ONy), a biaxially oriented polyester film (PET), a printed paper, a metal foil (AL foil), or a transparent vapor deposition film to the multilayer film to form a laminate. The laminate can be preferably manufactured by a normal dry lamination method in which the films constituting the laminate are bonded together using an adhesive, but if necessary, a method in which the multilayer film is directly extrusion laminated onto the substrate can also be employed.

The laminate structure of the laminate can be adjusted as appropriate according to the required properties of the packaging material, such as barrier properties that meet the shelf life of the packaged food, size and impact resistance that can accommodate the weight of the contents, visibility of the contents, etc.

<Packaging>
The packaging body may be made from the above packaging material, and there is no particular restriction on the form of the bag. For example, the above packaging material (laminate) can be used for a flat bag, a three-sided bag, a palm-shaped bag, a gusseted bag, a standing pouch, a pouch with a spout, a pouch with a beak, etc., using a multilayer film as a sealing material.

The present invention will be described in detail below using examples, but the present invention is not limited to the following examples.

<Preparation of Laminated Film>
Example 1
The following propylene homopolymer (A), non-crosslinked olefin-based thermoplastic elastomer (B), propylene-ethylene block copolymer (C), and ethylene-propylene copolymer elastomer (D) were prepared.

(Propylene homopolymer (A))
A propylene homopolymer having a melting onset temperature of 153°C, a melting peak temperature of 159°C, and a melt flow rate (MFR: ISO 1133) (temperature 230°C, load 2.16 kg) of 3.0 g/10 min when measured by differential scanning calorimetry (JIS K 7121).

(Non-crosslinked olefin-based thermoplastic elastomer (B))
WELNEX ^™ RFX4V (MFR: ISO 1133 (temperature 230° C., load 2.16 kg) 6.0 g/10 min) manufactured by a gas phase polymerization process using a metallocene catalyst, manufactured by Japan Polypropylene Corporation.

(Propylene-Ethylene Block Copolymer (C))
A propylene-ethylene block copolymer having a melt flow rate (MFR: ISO 1133) (temperature 230°C, load 2.16 kg) of 2.0 g/10 min, containing 77.1 mass% propylene polymer, 22.9 mass% ethylene-propylene copolymer, and the ethylene content of the ethylene-propylene copolymer is 28.7 wt%.

(Ethylene-propylene copolymer elastomer (D))
An ethylene-propylene copolymer elastomer having a melt flow rate (MFR: ISO 1133) (temperature 230° C., load 2.16 kg) of 0.6 g/10 min and a propylene content/ethylene content ratio of 2.7.

For the outer layer, a resin mixture in which 90% by mass of propylene homopolymer (A) and 10% by mass of non-crosslinked olefin-based thermoplastic elastomer (B) were mixed in pellet form was used, and for the inner layer, a resin mixture in which 83% by mass of propylene-ethylene block copolymer (C) and 17% by mass of ethylene-propylene copolymer elastomer (D) were mixed in pellet form was used. Each raw material was fed to an extruder whose temperature was adjusted to 250°C, kneaded in a molten state, and laminated in a T-die extruder with a feed block so that the first and second outer layers were each 10 μm thick, and the inner layer was 40 μm thick, to produce the film of Example 1.

Example 2
A film of Example 2 was produced in the same manner as in Example 1, except that the mixing ratio of the propylene homopolymer (A) and the non-crosslinked olefin-based thermoplastic elastomer (B) was changed as shown in Table 1.

Example 3
The film of Example 3 was produced in the same manner as in Example 1, except that the mixing ratio of the propylene homopolymer (A) and the non-crosslinked olefin-based thermoplastic elastomer (B) was changed as shown in Table 1.

(Comparative Example 1)
A film of Comparative Example 1 was produced in the same manner as in Example 1, except that the mixing ratio of the propylene homopolymer (A) and the non-crosslinked olefin-based thermoplastic elastomer (B) was changed as shown in Table 1.

(Comparative Example 2)
A film of Comparative Example 2 was produced in the same manner as in Example 1, except that the outer layer was formed using only the propylene homopolymer (A).

(Comparative Example 3)
A film of Comparative Example 3 was produced in the same manner as in Example 1, except that the outer layer was formed using only the following propylene-ethylene random copolymer (E).
(Propylene-Ethylene Random Copolymer (E))
A propylene-ethylene random copolymer having a melting onset temperature of 142° C., a melting peak temperature of 147° C., and an ethylene content of 3.4% by mass, as measured by differential scanning calorimetry (JIS K 7121).

(Comparative Example 4)
The film of Comparative Example 4 was produced in the same manner as in Example 1, except that the outer layer was formed using a resin mixture obtained by mixing 70% by mass of a propylene homopolymer (A) and 30% by mass of a propylene-ethylene random copolymer (E) in a pellet state.

(Comparative Example 5)
The film of Comparative Example 5 was produced in the same manner as in Example 1, except that the outer layer was formed using a resin mixture obtained by mixing 50 mass% of the propylene homopolymer (A) and 50 mass% of the propylene-ethylene random copolymer (E) in a pellet state.

(Comparative Example 6)
A film of Comparative Example 6 was formed in the same manner as in Example 1, except that the outer layer was formed using a resin mixture obtained by mixing 85% by mass of a propylene homopolymer (A) and 15% by mass of the following elastomer resin in a pellet state.
(Elastomer resin)
An olefin-based elastomer resin using a metallocene catalyst, with ethylene as the main monomer and butene-1 as the comonomer, and having a melt flow rate (MFR: ISO 1133) (temperature 190°C, load 2.16 kg) of 3.6 g/10 min.

(Comparative Example 7)
A resin mixture obtained by mixing 83% by mass of the propylene-ethylene block copolymer (C) and 17% by mass of the ethylene-propylene copolymer elastomer (D) in a pellet state was used to produce a film of Comparative Example 7 having a thickness of 60 μm.

<Various evaluations>
The films obtained in each example were subjected to the following evaluations, and the results are shown in Table 1.

[Haze measurement after retort]
The evaluation was performed using a haze meter (model number HM-150) manufactured by Murakami Color Research Laboratory in accordance with the haze measurement method described in JIS K 7136. A post-retort haze of 10% or less was judged to be good.

[Cold impact resistance evaluation]
Using a heat sealer manufactured by Tester Sangyo Co., Ltd., the films obtained in each example were heat-sealed together under the conditions of a sealing pressure of 0.2 MPa, a sealing time of 1 second, a sealing width of 5 mm, and a sealing temperature of 200°C, to create a three-sided bag with a bag size (inner dimensions) of 90 mm x 160 mm. After filling this bag with 100 ml of 0.1% saline solution, it is retorted at 135°C for 40 minutes. The bag after the retort treatment is stored in a refrigerator at 0°C for 3 days, and the sample is taken out from 0°C to room temperature and immediately dropped vertically from a height of 0.7 m. The number of samples was n = 10, and the ratio of bags that did not break when the bag was dropped 10 times (survival rate) was evaluated. Regarding cold impact resistance, a survival rate of 30% or more was judged to be good.

[Heat resistance evaluation]
Using a heat sealer manufactured by Tester Sangyo Co., Ltd., the films obtained in each example were heat-sealed together under the conditions of a sealing pressure of 0.03 MPa, a sealing time of 30 seconds, a sealing width of 10 mm, and a sealing temperature of 135° C. The heat-sealed film was then cut into a 15 mm wide x 80 mm piece, and a tensile tester manufactured by Shimadzu Corporation was used to perform T-peel at a tensile speed of 300 mm/min to measure the fusion strength of the heat-sealed portion. For the heat resistance evaluation, a fusion strength of 2 N/15 mm or less was judged to be good.

The films according to Examples 1 to 3 contained 75 to 90% by mass of propylene homopolymer (A) and 10 to 25% by mass of non-crosslinked olefin-based thermoplastic elastomer (B), and therefore were excellent in all of transparency, cold impact resistance, and heat resistance. In contrast, the film according to Comparative Example 1, in which the blending ratio of propylene homopolymer (A) and non-crosslinked olefin-based thermoplastic elastomer (B) is outside the range of the present invention, and the film according to Comparative Example 2, which does not contain non-crosslinked olefin-based thermoplastic elastomer (B), were inferior in at least cold impact resistance compared to the respective Examples. In addition, the film according to Comparative Example 7 had low transparency because the surface unevenness of the film could not be suppressed due to the absence of an outer layer.

The polypropylene-based multilayer film of the present invention combines high levels of heat resistance, cold impact resistance, and transparency, making it suitable for use as a sealant film for retort packaging.

10: Polypropylene-based multilayer film, 1a: First outer layer, 1b: Second outer layer, 2: Inner layer

Claims (6)

A first outer layer containing 75 to 90% by mass of a propylene homopolymer (A) and 10 to 25% by mass of a non-crosslinked olefin-based thermoplastic elastomer (B);
an inner layer made of a material containing a propylene-ethylene block copolymer (C);
a second outer layer containing, in this order, 75 to 90% by mass of a propylene homopolymer (A) and 10 to 25% by mass of a non-crosslinked olefin-based thermoplastic elastomer (B). The multilayer film according to claim 1, wherein the inner layer contains 50 to 90% by mass of the propylene-ethylene block copolymer (C) and 10 to 50% by mass of the ethylene-propylene copolymer elastomer (D). The multilayer film according to claim 1 or 2, wherein the total thickness of the first outer layer and the second outer layer is 16 to 42% based on the thickness of the multilayer film. The multilayer film according to any one of claims 1 to 3, wherein the thickness of the inner layer is 20 μm or more. A packaging material comprising the multilayer film according to any one of claims 1 to 4 and a substrate. A package made from the packaging material according to claim 5.

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