TW202003247A - Multilayer film and food packaging bag - Google Patents

Abstract

This multilayer film is obtained by layering a surface layer (A), an intermediate layer (B), and a seal layer (C). The surface layer (A), the intermediate layer (B), and the seal layer (C) each contain a propylene resin. The intermediate layer (B) additionally contains a plant-derived polyethylene (b1). By setting the melt flow rate of the polyethylene (b1) to 2.5 g/10 min or less, it is possible to maintain high transparency and obtain an environmentally friendly film in which transparency varies little even when the amount of said polyethylene (b1) is changed.

Description

Laminated film and food packaging bags

The present invention relates to a laminated film using a plant-derived resin and a food packaging bag.

In recent years, for the purpose of reducing the environmental load, it is being considered to replace part of the materials constituting the resin film used for packaging materials from resins derived from fossil fuels such as petroleum to resins derived from plants (see, for example, Patent Documents 1 and 2 ).

Although plant-derived resins are highly environmentally responsive, they often show properties different from fossil fuel-derived resins. Therefore, if only a part of the material constituting the resin film is replaced with a plant-derived resin, the characteristic of the purpose of the resin film may not be obtained.

[Prior Technical Literature] [Patent Literature]

Patent Document 1: Japanese Patent Laid-Open No. 2012-167172

Patent Document 2: Japanese Patent Laid-Open No. 2013-151623

In particular, if a plant-derived polyethylene is used as a heat-sealable resin film (laminated film) mainly composed of an acrylic resin, heat-sealability, impact resistance, and transparency may decrease. .

The problem to be solved by the present invention is to provide a laminated film having a suitable heat sealability and impact resistance in a film structure mainly composed of acrylic resin and having high transparency, and the use (bag making) of such Food packaging bag of laminated film.

The present invention solves the above-mentioned problems through a laminated film which is a laminated film having a surface layer (A), an intermediate layer (B) and a sealing layer (C), the surface layer (A) and the intermediate layer ( B) and the sealing layer (C) each contain a propylene-based resin, the intermediate layer (B) further contains plant-derived polyethylene (b1), and the melt flow rate of the polyethylene (b1) is 2.5 g/10 Less than minutes.

The laminated film of the present invention is composed of a propylene resin as the main film, and by using a plant-derived polyethylene with a specified melt flow rate, it can be made to maintain high transparency while changing its content. Environmentally-responsive film with little change in transparency. In addition, the laminated film of the present invention can be suitably used for packaging food such as bread.

[Form for carrying out the invention]

Hereinafter, the laminated film and the food packaging bag of the present invention will be described in detail based on suitable embodiments.

The laminated film of the present invention has at least a surface layer (A), an intermediate layer (B), and a sealing layer (C), and one of the surface layers is a surface layer (A), and the other surface layer is a sealing layer (C).

For the purpose of the present invention, the surface layer (A), the intermediate layer (B) and the sealing layer (C) each contain an acrylic resin, and the intermediate layer (B) further contains plant-derived polyethylene (b1) (hereinafter referred to as "Biopolyethylene (b1)".).

Hereinafter, the structure of each layer (A) to (C) will be described in order.

[Surface layer (A)]

The surface layer (A) is a layer that constitutes the surface layer when the laminated film bag is made into a food packaging bag, and functions as a printed layer to be printed and the like.

This surface layer (A) contains an acrylic resin.

Since it is easy to impart proper fuse sealing and bag-making suitability to the laminated film, the content of the acrylic resin in the resin component contained in the surface layer (A) is preferably 50% by mass or more, and more preferably 70% by mass or more. It is further preferably 80% by mass or more, and particularly preferably 85% by mass or more. In addition, the resin component contained in the surface layer (A) may contain substantially only the propylene-based resin.

For the propylene-based resin, for example, a propylene homopolymer, a propylene-α-olefin copolymer (propylene-α-olefin random copolymer, propylene-α-olefin block copolymer), or the like can be used.

The α-olefin content in the propylene-α-olefin copolymer is preferably 10% by mass or less, more preferably 8% by mass or less, and still more preferably 6% by mass. In addition, since it is easy to impart appropriate impact resistance to the laminated film, the α-olefin content is preferably 2% by mass or more, more preferably 3% by mass or more, and still more preferably 4% by mass or more.

In order to make the laminated film of the present invention into a film with high transparency (transparent film), as the propylene-based resin, a propylene-α-olefin random copolymer can be preferably used.

Examples of propylene-α-olefin random copolymers include propylene-ethylene random copolymers, propylene-1-butene random copolymers, propylene-ethylene-1-butene random copolymers, and the like. These may be used alone or in combination. Among them, the propylene-α-olefin random copolymer is preferably used as the propylene-α-olefin random copolymer because it is easy to impart appropriate transparency to the laminated film.

The melt flow rate (MFR) of the propylene-ethylene random copolymer is not particularly limited as long as it can form a laminated film, and is preferably 0.5 g/10 minutes or more, more preferably 3 g/10 minutes or more, and further It is preferably 5 g/10 minutes or more. In order to obtain good moldability of the laminated film, the MFR is preferably 20 g/10 minutes or less, more preferably 15 g/10 minutes or less, and still more preferably 12 g/10 minutes or less.

In addition, in this specification, unless otherwise stated, MFR is measured in accordance with the provisions of JIS K 7210:1999 under the measurement conditions of a temperature of 230° C. and a load of 21.18 N.

The density of the propylene-ethylene random copolymer is preferably about 0.88 to 0.905 g/cm ³ , and more preferably about 0.89 to 0.9 g/cm ³ .

The melting point of the propylene-ethylene random copolymer is preferably 110° C. or higher, and more preferably 115° C. or higher from the viewpoint of preventing adhesion to the fuse seal knife during bag making. In addition, in the case of fuse sealing during bag making, in order for the laminated film to exhibit fuse sealing, it is necessary to form sufficient fuse balls. Therefore, the melting point is preferably 150°C or lower, and more preferably 145°C or lower.

Since it is easy to impart proper transparency and packaging suitability to the laminated film, the content of the propylene-ethylene random copolymer in the resin component contained in the surface layer (A) is preferably 35% by mass or more, more preferably 45% by mass or more It is further preferably 50% by mass or more. In addition, the content thereof is preferably 75% by mass or less, more preferably 65% by mass or less, and still more preferably 60% by mass or less.

In addition, since it is easy to form sufficient fuse balls during fuse sealing, a lower melting point propylene-1-butene random copolymer or propylene-ethylene-1-butene random copolymer is used together with the propylene-ethylene random copolymer It is also better. Among them, a propylene-ethylene-1-butene random copolymer (propylene-ethylene-1-butene terpolymer) can be particularly preferably used.

The ethylene content and 1-butene content in the propylene-ethylene-1-butene random copolymer are preferably 25% by mass or less, more preferably 15% by mass or less, and still more preferably 10% by mass. In addition, since it is easy to impart suitable low-temperature sealing properties to the laminated film, the ethylene content and the 1-butene content are preferably 0.5% by mass or more, more preferably 1.5% by mass or more, and still more preferably 3% by mass or more.

The MFR of the propylene-ethylene-1-butene random copolymer is not particularly limited as long as it can form a laminated film, and is preferably 0.5 g/10 minutes or more, more preferably 3.0 g/10 minutes or more, and further It is preferably 5.0 g/10 minutes or more. In order to obtain good moldability of the laminated film, the MFR is preferably 20 g/10 minutes or less, more preferably 15 g/10 minutes or less, and still more preferably 12 g/10 minutes or less.

The density of the propylene-ethylene-1-butene random copolymer is preferably about 0.88 to 0.905 g/cm ³ , more preferably about 0.89 to 0.9 g/cm ³ .

The melting point of the propylene-ethylene-1-butene random copolymer is preferably 105° C. or higher, and more preferably 110° C. or higher from the viewpoint of preventing adhesion to the fuse seal knife during bag making. In addition, in the case of fuse sealing during bag making, in order for the laminated film to exhibit fuse sealing, it is necessary to form sufficient fuse balls. Therefore, the melting point is preferably 145°C or lower, and more preferably 140°C or lower.

Since it is easy to impart proper fuse sealing to the laminated film, the content of the propylene-ethylene-1-butene random copolymer in the resin component contained in the surface layer (A) is preferably 15% by mass or more, and more preferably 25% by mass % Or more, further preferably 30% by mass or more. In addition, the content thereof is preferably 55% by mass or less, more preferably 45% by mass or less, and still more preferably 40% by mass or less.

For the surface layer (A), various olefin-based resins used for packaging films other than the above-mentioned propylene-based resins can also be used. Examples of such olefin-based resins include ethylene-based single polymers, ethylene-based copolymers, and ionomers of ethylene-(meth)acrylic acid copolymers. These may be used alone or in combination.

Examples of the ethylene-based single polymer include ultra low density polyethylene (VLDPE), linear low density polyethylene (LLDPE), and low density polyethylene (LDPE).

Examples of the ethylene-based copolymer include ethylene-1-butene copolymer, ethylene-vinyl acetate copolymer (EVA), ethylene-methyl methacrylate copolymer (EMMA), and ethylene-ethyl acrylate. Copolymer (EEA), ethylene-methyl acrylate (EMA) copolymer, ethylene-ethyl acrylate-maleic anhydride copolymer (E-EA-MAH), ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid Copolymer (EMAA), etc.

Furthermore, the content of these olefin-based resins in the resin component contained in the surface layer (A) is preferably 20% by mass or less.

Among them, ethene-1-based resins other than propylene-based resins can be preferably used because of their flexibility in the wide temperature range that is effective and good dispersibility with propylene-based resins. Butene copolymer (crystalline ethylene-1-butene copolymer). Especially when the laminated film is made into a transparent film, an ethylene-1-butene copolymer can be particularly preferably used.

Since it is easy to impart a suitable low-temperature sealability to the laminated film, the content of the ethylene-1-butene copolymer in the resin component contained in the surface layer (A) is preferably about 1 to 20% by mass, more preferably 5 to 15 About mass%.

The MFR of the ethylene-1-butene copolymer is not particularly limited as long as it can form a laminated film, and is preferably 0.5 g/10 min or more, more preferably 2 g/10 min or more, and still more preferably 3 g /10 minutes or more. In order to obtain good moldability of the laminated film, the MFR is preferably 20 g/10 minutes or less, more preferably 15 g/10 minutes or less, and even more preferably 10 g/10 minutes or less.

The density of the ethylene-1-butene copolymer is preferably about 0.87 to 0.9 g/cm ³ , more preferably about 0.875 to 0.895 g/cm ³ .

In addition, as for the surface layer (A), a plant-derived resin may be used in combination. When the use ratio of the plant-derived resin contained in the laminated film (hereinafter also referred to as "biologicality") is to be increased, it is preferable to derive from the resin component contained in the surface layer (A) The content of the plant resin is set to 10% by mass or more, more preferably 20 to 50% by mass.

On the other hand, when attaching importance to various characteristics such as heat sealability, fuse sealability, and impact resistance of the laminated film, it is preferable to set the content of the plant-derived resin in the resin component contained in the surface layer (A) It is less than 10% by mass, more preferably less than 5% by mass, and still more preferably substantially 0% by mass.

The surface layer (A) may be composed only of a resin containing a propylene-based resin, and may contain various additives within a range that does not impair the effects of the present invention. Examples of the additives include antioxidants, weathering stabilizers, antistatic agents, anti-fogging agents, anti-caking agents, lubricants, nucleating agents, and pigments.

The surface of the surface layer (A) has a surface roughness (Ra) specified in JIS B 0601:2001 of preferably about 0.2 to 1, more preferably about 0.3 to 0.7. By setting the surface roughness (Ra) to the aforementioned range, even if the additional amount of other additives (such as slipping agent, anti-caking agent, etc.) is reduced, or without the combined use, excellent surface smoothness can be obtained Laminated film. Therefore, while increasing the speed of bag making, it is also possible to achieve alignment after bag making, increase/efficiency of the packaging operation, and to improve workability when packaging by filling the contents with an automatic packaging machine or the like.

The friction coefficient of the surface of the surface layer (A) specified by ASTM D 1894-95 is preferably about 0.05 to 0.7, more preferably about 0.07 to 0.6, and still more preferably about 0.1 to 0.5. By setting the friction coefficient to the aforementioned range, it becomes easy to improve the film transportability at the time of packaging, the alignment after bag making, the packing workability, and the like. In addition, it becomes easy to appropriately suppress film breakage during binding due to the binding tool. Furthermore, the friction coefficient can be adjusted by appropriately adding additives such as a slip material and an anti-caking agent according to the resin component used in the surface layer (A).

[Middle layer (B)]

The intermediate layer (B) is a layer having a function of imparting characteristics to the laminated film, which is a characteristic required when making a food packaging bag and a characteristic required as a food packaging bag.

This intermediate layer (B) contains a propylene-based resin and further contains biopolyethylene (b1). According to the present invention, the MFR of biopolyethylene (b1) is 2.5 g/10 minutes or less.

By containing the propylene-based resin, it is possible to impart good heat-sealability to the laminated film, suitable fuse-sealing performance in a wide temperature range, and at the same time to impart appropriate impact resistance and bag-break resistance.

In addition, by containing biopolyethylene (b1) having an MFR of 2.5 g/10 minutes or less, the high transparency of the laminated film can be maintained. Moreover, even if the content of the biopolyethylene (b1) is changed, the change in the transparency of the laminated film can be suppressed.

Here, the transparency of the laminated film can be expressed as a value (unit: %) of turbidity (haze).

The degree of change in the transparency of the laminated film due to the change in the content of biopolyethylene (b1) is preferably as follows. In general, when the content of biopolyethylene (b1) in the resin component contained in the intermediate layer (B) is increased, the transparency of the laminated film tends to decrease (the turbidity tends to increase).

When the content of biopolyethylene (b1) in the resin component contained in the intermediate layer (B) is 10% by mass, the value of the turbidity of the laminated film at this time is set to A (%), when the content is 35% by mass When the value of turbidity at this time is B (%), the change rate shown by (BA)/(35-10) is preferably 0.1 or less, more preferably 0.08 or less, and still more preferably 0.06 or less. If the rate of change is within such a range, it can be said that the change in the transparency of the laminated film is sufficiently small.

In addition, by using biopolyethylene (b1), the biofilm of the laminated film can be improved, which also contributes to the reduction of carbon dioxide emissions and can improve the environmental response.

The MFR of the biopolyethylene (b1) may be 2.5 g/10 minutes or less, but is preferably about 1 to 2.5 g/10 minutes, and more preferably about 1.5 to 2.5 g/10 minutes. By using such MFR biopolyethylene (b1), the laminated film can maintain higher transparency regardless of the content of biopolyethylene (b1).

Biopolyethylene (b1) uses plants such as sugarcane, corn, sugar beet as raw materials to produce monomer (ethylene), and can be produced in the same manner as the production method of polyethylene using monomers derived from petroleum.

The manufacturing method is not particularly limited, but a known method can be used, and for example, a method using a Ziegler-Natta catalyst or a metallocene catalyst can be cited.

Specifically, it is possible to suitably use a catalyst that supports a titanium-containing compound itself or a carrier that supports a titanium-containing compound on a carrier such as a magnesium compound as a main catalyst and uses an organoaluminum compound as an auxiliary catalyst Under the system, propylene is added alone, or a desired α-olefin (for example, ethylene, etc.) is added to propylene to perform polymerization.

For this polymerization, any process such as slurry polymerization, solution polymerization, and gas phase polymerization can also be used.

In addition, for polymerization, a homogeneous catalyst can also be used. For this homogeneous catalyst, a catalyst composed of a vanadium compound and an organoaluminum compound used in the past; or a compound having a cyclopentadienyl group, a substituted cyclopentadienyl group, an indenyl group, and a substituted indene group can be cited. One or two transition metal compounds such as zirconium, titanium, hafnium, etc., which are ligands, and the ligand is geometrically controlled. The transition metal compound is composed of an auxiliary catalyst such as aluminoxane or ionic compound. Metallocene catalysts, etc.

The metallocene-based catalyst may use an organoaluminum compound in combination as needed, and can be used in processes such as slurry polymerization and gas-phase polymerization in addition to homogeneous polymerization in the presence of a solvent.

Examples of biopolyethylene (b1) include linear low-density polyethylene (LLDPE), linear medium-density polyethylene (LMDPE), linear high-density polyethylene (LHDPE), and low-density polymer. Ethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), etc. These may be used alone or in combination. Among them, the biopolyethylene (b1) is preferably a linear low-density polyethylene. By using linear low-density polyethylene, it is possible to impart high transparency to the laminated film and excellent impact resistance.

The density of the linear low-density polyethylene is preferably 0.925 g/cm ³ or less, and more preferably 0.92 g/cm ³ or less. By setting the density of the linear low-density polyethylene to the aforementioned range, the laminated film can easily have appropriate fuse sealing performance, high impact resistance, and bag resistance.

Examples of such commercially available products of biopolyethylene (b1) include SLL218, SLL318, SLH218, SBC818, SPB208, and SEB853 manufactured by Braskem.

Due to the high environmental load reduction effect on one side, it is easy to impart high transparency, appropriate rigidity and impact resistance to the laminated film, and the content of biopolyethylene (b1) in the resin component contained in the intermediate layer (B) is better It is 35% by mass or less, more preferably 25% by mass or less, and more preferably about 5-20% by mass.

The intermediate layer (B) may further contain polyethylene (b2) derived from fossil fuels. The propylene-based resin used in the intermediate layer (B) is also a resin derived from fossil fuels, so the affinity (miscibility) of the polyethylene (b2) and the propylene-based resin is high. Therefore, when bio-low-density polyethylene (b1) is used in combination, the presence of polyethylene (b2) makes it easy to uniformly mix bio-low-density polyethylene (b1) with the propylene-based resin. As a result, the characteristics of the intermediate layer (B) can be made uniform.

The polyethylene (b2) includes, for example, ethylene-based single polymers, ethylene-based copolymers, and ionomers of ethylene-(meth)acrylic acid copolymers. These may be used alone or in combination.

Examples of ethylene-based single polymers include linear low-density polyethylene (LLDPE), linear medium-density polyethylene (LMDPE), linear high-density polyethylene (LHDPE), and low-density polyethylene. (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE).

Examples of the ethylene-based copolymer include ethylene-butene-rubber copolymer (EBR), ethylene-propylene-rubber copolymer (EPR), ethylene-vinyl acetate copolymer (EVA), and ethylene-methyl Methyl acrylate copolymer (EMMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate (EMA) copolymer, ethylene-ethyl acrylate-maleic anhydride copolymer (E-EA-MAH), Ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA), etc.

Among them, the polyethylene (b2) is preferably a linear low-density polyethylene. By using linear low-density polyethylene as the polyethylene (b2), the impact resistance of the laminated film can be further improved.

The MFR of polyethylene (b2) is preferably about 2 to 10 g/10 minutes, more preferably about 3 to 5 g/10 minutes. By using such MFR polyethylene (b2), it is easy to improve the film-forming properties of the laminated film, and the dispersibility of polyethylene (b2) in the intermediate layer (B) is also good, so it becomes easy to impart to the laminated film Uniform characteristics.

The density of polyethylene (b2) is preferably 0.915 g/cm ³ or less, more preferably 0.91 g/cm ³ or less, and still more preferably 0.906 g/cm ³ or less. By using polyethylene (b2) having such a density, it becomes easy to impart suitable fuse sealing properties, high impact resistance, and bag resistance to the laminated film.

The content of polyethylene (b2) in the resin component contained in the intermediate layer (B) is appropriately set in consideration of the following: while maintaining good film-forming properties and moldability of the laminated film, and appropriately imparting appropriate values to the laminated film Rigidity, impact resistance, suitability for bag making, etc. Specifically, the content of polyethylene (b2) is preferably about 5 to 20% by mass, and more preferably about 5 to 15% by mass.

Since it is easy to impart proper fuse sealing and bag making suitability to the laminated film, the content of the acrylic resin in the resin component contained in the intermediate layer (B) is preferably about 50 to 90% by mass, more preferably 60 to 85 The mass% is about 70 to 80 mass %.

For the propylene resin of the intermediate layer (B), the same propylene resin as the surface layer (A) can be used, for example, propylene homopolymer, propylene-α-olefin copolymer (propylene-α-olefin random copolymer, Propylene-α-olefin block copolymer), etc.

In the present invention, since the laminated film is a transparent film, the propylene-based resin preferably contains at least one of a propylene homopolymer and a propylene-α-olefin random copolymer.

The MFR of the propylene homopolymer is not particularly limited as long as it can form a laminated film, and is preferably 0.5 g/10 minutes or more, more preferably 2 g/10 minutes or more, and still more preferably 3 g/10 minutes or more . In order to obtain good moldability of the laminated film, the MFR is preferably 20 g/10 minutes or less, more preferably 15 g/10 minutes or less, and even more preferably 10 g/10 minutes or less.

The density of the propylene homopolymer is preferably about 0.88 to 0.92 g/cm ³ , more preferably about 0.885 to 0.915 g/cm ³ .

From the viewpoint of sufficiently maintaining the processing suitability of laminated films such as bags, the melting point of the propylene homopolymer is preferably 145°C or higher, and more preferably 150°C or higher.

Since it is easy to impart appropriate rigidity and transparency to the laminated film, the content of the propylene homopolymer in the resin component contained in the intermediate layer (B) is preferably about 35% by mass, more preferably 45% by mass or more, and still more preferably It is 55% by mass or more. In addition, since it is easy to impart appropriate impact resistance to the laminated film, it is preferably 90% by mass or less, more preferably 85% by mass or less, and still more preferably 80% by mass or less.

The MFR of the propylene-α-olefin random copolymer is not particularly limited as long as it can form a laminated film, and is preferably 0.5 g/10 min or more, more preferably 3 g/10 min or more, and still more preferably 5 g /10 minutes or more. In order to obtain good moldability of the laminated film, the MFR is preferably 20 g/10 minutes or less, more preferably 15 g/10 minutes or less, and still more preferably 12 g/10 minutes or less.

The density of the propylene-α-olefin random copolymer is preferably about 0.88 to 0.905 g/cm ³ , more preferably about 0.89 to 0.9 g/cm ³ .

The melting point of the propylene-α-olefin random copolymer is preferably 110° C. or higher, and more preferably 115° C. or higher from the viewpoint of preventing adhesion to the fuse seal knife during bag making. In addition, in the case of fuse sealing during bag making, in order for the laminated film to exhibit proper fuse sealing, it is necessary to form sufficient fuse balls. Therefore, the melting point is preferably 150°C or lower, and more preferably 145°C or lower.

The α-olefin content in the propylene-α-olefin random copolymer is not particularly limited, but it is preferably about 1 to 20% by mass, and more preferably about 1.5 to 15% by mass.

Examples of such a propylene-α-olefin random copolymer include a propylene-ethylene random copolymer, a propylene-1-butene random copolymer, and a propylene-ethylene-1-butene random copolymer. These may be used alone or in combination. Among them, the propylene-α-olefin random copolymer is preferably used as the propylene-α-olefin random copolymer because it is easy to impart appropriate transparency to the laminated film.

By containing a propylene-ethylene random copolymer, the propylene-based resin can improve the affinity (miscibility) of the propylene-based resin with biopolyethylene (b1) and/or polyethylene (b2).

Since it is easy to impart proper bag-making suitability and bag-breaking resistance to the laminated film, the content of the propylene-α-olefin random copolymer in the resin component contained in the intermediate layer (B) is preferably about 10 to 50% by mass , More preferably about 10 to 45% by mass.

The intermediate layer (B) may be composed only of a resin containing propylene-based resin and biopolyethylene (b1), and may contain various additives within a range that does not impair the effects of the present invention. Examples of the additives include antioxidants, weathering stabilizers, antistatic agents, anti-fogging agents, anti-caking agents, lubricants, nucleating agents, and pigments.

[Sealing layer (C)]

The sealing layer (C) is used for adhering the sealing layers (C) of the laminated film to each other or for adhering the laminated film to other containers or films.

The sealing layer (C) contains an acrylic resin. By containing the propylene-based resin, high adhesion between the sealing layer (C) and the intermediate layer (B) can be obtained.

Since it is easy to impart suitable sealing properties to the laminated film, the content of the propylene-based resin in the resin component contained in the sealing layer (C) is preferably 50% by mass or more, more preferably 70% by mass or more, and still more preferably 90% by mass % Or more, in fact, 100% by mass.

In addition, the sealing layer (C) may be formed in such a manner as to appropriately select a resin type that can obtain a suitable sealing strength in accordance with the aspect of use and the object to be sealed.

For example, when sealing layers (C) are sealed to each other and used as a packaging bag, from the viewpoint of obtaining a moderate seal strength, the propylene-based resin preferably contains, for example, propylene-ethylene random copolymer, propylene-1 -Propylene-α-olefin random copolymer like butene random copolymer, α-olefin-propylene random copolymer like 1-butene-propylene random copolymer.

Among them, the propylene-based resin preferably includes a butene-based random copolymer such as a propylene-1-butene random copolymer and a 1-butene-propylene random copolymer. This is because, if such a propylene resin containing a butene-based random copolymer is used, it is easy to adjust the heat sealing temperature and strength at the time of easy opening and sealing at a low temperature, and the heat sealing temperature range is large and easy A moderate heat seal strength is obtained in terms of easy-open seal.

Since it is easy to give proper sealing and blocking resistance to the laminated film, the content of 1-butene in the butene-based random copolymer is preferably about 60 to 95 mol%, more preferably about 65 to 95 mol% It is further preferably about 70 to 90 mol%. In addition, since it is easy to impart suitable low-temperature sealing properties to the laminated film, the propylene content is preferably about 2 to 10 mol%, more preferably about 3 to 9 mol%, and even more preferably about 4 to 8 mol%.

The content of the butene-based random copolymer in the resin component contained in the sealing layer (C) is preferably 50% by mass or less, more preferably 40% by mass or less, and still more preferably 30% by mass or less. In addition, the content thereof is preferably 10% by mass or more, and more preferably 15% by mass or more. If the content of the butene-based random copolymer is set to the aforementioned range, it is easy to impart a suitable low-temperature sealability, fuse sealability, and crack resistance to the laminated film, and it is also advantageous for cost reduction.

For the butene-based random copolymer, it is preferable to use another propylene-α-olefin random copolymer in combination.

The content of α-olefin in the propylene-α-olefin random copolymer is not particularly limited, but it is preferably about 1 to 20% by mass, and more preferably about 1.5 to 15% by mass. Examples of α-olefins include ethylene, 1-hexene, 4-methyl-1-pentene, and 1-octene.

Among them, as the propylene-α-olefin random copolymer, the same propylene-α-olefin random copolymer as the intermediate layer (B) can be used.

In addition, since it is easy to obtain good moldability of the laminated film, the MFR of the propylene-α-olefin random copolymer is preferably about 0.5 to 20 g/10 minutes, and more preferably about 2 to 10 g/10 minutes.

Since it is easy to impart a suitable low-temperature sealing property to the laminated film, the content of the other propylene-α-olefin random copolymer in the resin component contained in the sealing layer (C) is preferably 90% by mass or less, more preferably 85% by mass %the following. In addition, the content thereof is preferably 50% by mass or more, and more preferably 60% by mass or more.

Especially when a laminated film is used to form a packaging bag, when an easy-to-open seal portion that heat seals the sealing layers (C) with each other is provided, it is preferable to use a butene-based random copolymer/propylene-α-olefin The mass ratio of the random copolymer is about 20/80 to 50/50, and the butene-based random copolymer and the propylene-α-olefin random copolymer are used in combination.

Furthermore, the sealing layer (C) may contain a plant-derived polyolefin (for example, plant-derived polyethylene (b1) as described above). From the viewpoint of improving the biomass, the content of the plant-derived polyolefin in the resin component contained in the sealing layer (C) is preferably 10% by mass or more, and more preferably 20-50% by mass %about.

On the other hand, when emphasis is placed on characteristics such as fuse sealability and impact resistance of the laminated film, the content of the plant-derived polyolefin is preferably less than 10% by mass, more preferably less than 5% by mass, It is further preferably set to substantially 0% by mass.

The sealing layer (C) may be composed only of a resin containing a propylene-based resin, and may contain various additives within a range that does not impair the effects of the present invention. Examples of the additives include antioxidants, weathering stabilizers, antistatic agents, anti-fogging agents, anti-caking agents, lubricants, nucleating agents, and pigments.

The friction coefficient of the surface of the sealing layer (C) specified by ASTM D 1894-95 is preferably about 0.01 to 0.4, more preferably about 0.02 to 0.35, and even more preferably about 0.05 to 0.3. By setting the friction coefficient to the aforementioned range, it becomes easier to improve the workability of the packaging operation due to the film transportability during packaging, the suppression of wrinkles or protrusions after bag making.

In addition, when filling contents such as bread, even if the contents rub against the inner surface of the laminated film (the surface of the sealing layer (C)), the occurrence of scratches can be suppressed. Further, it is easy to impart abrasion resistance and crack resistance to the laminated film, and it is also possible to appropriately suppress film breakage. Furthermore, the coefficient of friction can be adjusted by appropriately adding additives such as slip materials and anti-caking agents according to the resin component used in the sealing layer (C).

[Laminated Film]

The laminated film of the present invention is a laminated film having the above surface layer (A), intermediate layer (B) and sealing layer (C), wherein the intermediate layer (B) contains a source having a melt flow rate of 2.5 g/10 minutes or less Plant-derived polyethylene (b1). With this configuration, the laminated film of the present invention can achieve suitable heat sealability and impact resistance while achieving suitable transparency even when biopolyethylene is contained in a film structure mainly composed of an acrylic resin.

The average thickness of the laminated film may be adjusted appropriately according to the application and appearance of the bag to be made. However, it is preferably about 25-50 μm because it is easy to take into account volume reduction and bag resistance during delivery. More preferably, it is about 30 to 45 μm.

The proportion of each layer in the thickness of the laminated film and the specific thickness of each layer are not particularly limited, but can be set as follows.

The proportion of the surface layer (A) is preferably about 1 to 35%, more preferably about 5 to 25%.

The proportion of the intermediate layer (B) is preferably about 45% to 85%, more preferably about 50% to 75%.

The proportion of the sealing layer (C) is preferably about 5 to 20%, more preferably about 10 to 20%.

The specific average thickness of the surface layer (A) is preferably about 0.5 to 15 μm, and more preferably about 1 to 10 μm.

The specific average thickness of the intermediate layer (B) is preferably about 5 to 35 μm, and more preferably about 10 to 25 μm.

The specific average thickness of the sealing layer (C) is preferably about 1 to 20 μm, more preferably about 5 to 10 μm.

Moreover, from the viewpoint of improving environmental response, the content of biopolyethylene in the resin component contained in the entire laminated film is preferably 2% by mass or more, more preferably 3% by mass or more, and still more preferably 5% by mass %the above.

Since the contents of the package can be easily recognized, the turbidity (haze) of the laminated film is preferably 6% or less, more preferably 5.5% or less, further preferably 5.0% or less, and particularly preferably 4.5% or less. In the case of such high transparency, even though the laminated film has proper packaging suitability, it also becomes less prone to breakage due to friction between the content and the film or cracking caused by rubbing.

In addition, in order to improve the transparency of the laminated film, it is preferable not to use a resin such as a block copolymer that causes the increase in turbidity in each layer, or to reduce the use amount as much as possible. In this case, the content of the block copolymer in the resin component contained in the entire laminated film is preferably 10% by mass or less, and more preferably 5% by mass or less.

Since it is easy to obtain suitable scratch resistance and bag resistance, the laminated film of the present invention preferably has a rigidity (MD) of 450 MPa or more, more preferably 550 MPa or more, and even more preferably 600 MPa or more. In addition, this rigidity is based on ASTM D 882-12, and the 1% tangent modulus of the obtained laminated film at 23° C. was measured using a Tensilon tensile tester (manufactured by A&D Co., Ltd.).

The impact strength of the laminated film of the present invention is preferably 0.10 J or more, and more preferably 0.15 J or more, since it is easy to suppress breakage of bags and leakage of contents when used as packaging materials. In addition, the impact strength was measured by a film impact method using a spherical metal impact head with a diameter of 1.5 inches after the laminated film was kept in a constant temperature chamber set at 0°C for 6 hours.

The laminated film of the present invention may have any other resin layer than the surface layer (A), the intermediate layer (B), and the sealing layer (C). However, the thickness of the other resin layer is preferably 20% or less of the overall thickness (total thickness) of the laminated film. The laminated film is particularly preferably composed of the surface layer (A), the intermediate layer (B), and the sealing layer (C) as described above. Furthermore, in such a structure, the intermediate layer (B) can also be composed of a laminated body in which a plurality of layers are laminated.

Specific examples of the layer configuration include a surface layer (A)/intermediate layer (B)/sealing layer (C) in which the intermediate layer (B) is provided between the surface layer (A) and the sealing layer (C) ) Of the three-layer structure, or the four-layer structure of the surface layer (A)/intermediate layer (B1)/intermediate layer (B2)/sealing layer (C) of the intermediate layer (B) using the laminate. Among them, since the adjustment of the characteristics of the laminated film and the production system of the laminated film are easy, it is preferably a three-layer structure composed of a surface layer (A)/intermediate layer (B)/sealing layer (C).

The method for manufacturing the laminated film is not particularly limited, but for example, a co-extrusion method can be used. For the co-extrusion method, the resin or resin mixture used in each layer is heated and melted by separate extruders, and the lamination is carried out in the molten state through the co-extrusion multilayer die method, feed block method, etc. Thereafter, through blow molding (inflation) or T-shaped mold. It is formed into a film shape by a cooling roll method or the like to obtain a laminated film.

According to the co-extrusion method, the ratio of the thickness of each layer can be adjusted relatively freely, and a laminated film with excellent hygiene and excellent cost performance can be obtained.

Furthermore, since the laminated film obtained by the above manufacturing method is obtained as a substantially non-stretched multilayer film, secondary forming such as deep drawing forming by vacuum forming is also possible.

In order to improve the adhesion (adhesion) of the printing ink and the like, it is also preferable to apply surface treatment to the surface of the surface layer (A). For such surface treatment, for example, corona discharge treatment, plasma treatment, chromic acid treatment, flame treatment, hot air treatment, ozone can be cited. Surface oxidation treatment like ultraviolet treatment, surface roughness treatment like sandblasting treatment, etc. These treatments can be used alone or in combination. Among them, corona discharge treatment is suitable in terms of surface treatment.

Examples of the packaging material composed of the laminated film of the present invention include packaging bags, containers, and covering materials for containers used for food, pharmaceuticals, industrial parts, groceries, magazines, and other purposes.

The packaging bag is preferably heat-sealed by superimposing the sealing layers (C) of the laminated film on each other, or by superimposing the surface layer (A) and the sealing layer (C) to perform heat sealing, thereby sealing the sealing layer (C) ) Is formed into a bag shape as the inner side.

For example, after cutting two laminated films to the size of a desired packaging bag, overlapping these and heat-sealing the three sides to form a bag shape, filling the contents from the opening that is not heat-sealed on one side, It can also be used as a packaging bag by heat sealing to seal the opening.

Furthermore, by pulling out the drum-shaped laminated film through an automatic packaging machine and heat-sealing the ends overlapped by the cylindrical shape, the upper end and the lower end are heat-sealed separately, whereby a packaging bag can also be formed.

Also, in the case of a packaging bag for long bread, the printed surface is folded inward and sealed, whereby a bag having a gusset portion (bottom gusset bag) can be made. Specifically, it is processed so that the sealing layer (C) of the laminated film of the present invention becomes the inside of the bag, and is processed by a bag-making machine (for example, "HK-40V" manufactured by Totani Technology Research Co., Ltd.) into Gusset bag at the bottom.

The laminated film of the present invention can be particularly suitably used for gusset bags at the bottom of the bag due to its proper fuse sealing and bag making suitability.

The fuse seal strength of the side edges of the bottom gusset bag and the bottom gusset (the inner fold of the bottom) is preferably 13N/15mm or more, more preferably 14N/15mm or more, and even more preferably 14.5N/15mm or more. Especially good is 16N/15mm or more. The upper limit is not particularly limited, but it is preferably 30 N/15 mm or less. By adjusting the fuse seal temperature and bag making speed during bag making, the fuse seal strength can be set.

The bottom gusset bag obtained is supplied to an automatic baguette filling machine, and after filling the baguette, it is heat-sealed so that it can be easily opened. The heat seal strength at this time is preferably less than 5N/15mm, more preferably 0.1N/15mm or more and less than 5N/15mm, and still more preferably 0.2N/15mm or more and less than 4N/15mm.

Afterwards, if necessary, the upper part of the bag can also be bound by using binding tools such as plastic plates, adhesive tapes, and ropes.

In addition, in the case of assembling packaging of various breads such as cream meal packs, the laminated film is supplied to the horizontal automatic packaging machine in the form of a roll with the sealing layer (C) as the inner side of the bag , Manufactured by FUJI MACHINERY Co., Ltd., "FW-3400αV type", etc.). Since the pillow package is also excellent in heat sealability and easy opening property, the laminated film of the present invention can also be particularly suitably used as a pillow packaging bag.

In the case of a horizontal automatic packaging machine, the sealing surfaces of the sealing layer (C) of the laminated film are stacked and heat-sealed to form a bag on one side and to wrap bread on the inside. The heat-sealing strength of the bottom and back side of the pillow-shaped packaging bag carried out by the packaging machine is preferably about 7.5 to 30 N/15 mm, more preferably about 10 to 30 N/15 mm. By adjusting the heat sealing temperature and packaging speed, the heat sealing strength can be set.

Then, the upper part of the pillow-shaped packaging bag may be heat-sealed to form an easily-openable sealable portion, or it may be bundled with a binding tool such as plastic plate, tape, rope, or the like. When an easy-to-open seal portion is formed, the heat seal strength is preferably less than 5N/15mm, more preferably 0.1N/15mm or more and less than 5N/15mm, further preferably 0.2N/15mm or more and less than 4N/15mm .

In addition, it is also possible to form a packaging bag, container or container lid by superimposing and sealing the sealing layer (C) with other films capable of heat sealing.

In this case, as for other films, films with relatively low mechanical strength composed of LDPE, EVA, polypropylene, etc. can be used. In addition, as for other films, a laminated film can also be used. The laminated film is a stretched film (for example, biaxially oriented) made of a film composed of LDPE, EVA, polypropylene, etc., and having relatively good tearability. Stretched polyethylene terephthalate film (OPET), biaxially stretched polypropylene film (OPP, etc.) are obtained by laminating.

As described above, since the laminated film of the present invention exerts suitable impact resistance and bag-break resistance, it can be suitably applied to various packaging applications. In particular, since the laminated film of the present invention exhibits excellent impact resistance even at low temperatures, it can be suitably used in food packaging applications where many are packaged and distributed at low temperatures.

Among them, when the laminated film of the present invention is applied to bread packaging such as long bread or confectionary bread using a bundling tool (bundle) with a sharp tip or hook portion, it is not likely to cause bag breakage during bundling, and Even if it comes into contact with the strapping tool or the transport container during transportation, pinholes and cracks are not likely to occur. In addition, pinholes and cracks caused by friction between the food and the inner surface (sealing surface) of the film, or friction and puncturing with the plastic disc mixed in are not likely to occur. Furthermore, since the laminated film of the present invention can ensure an appropriate fuse seal strength even when a gusset portion is formed, it is preferably applied to a packaging bag used for bread packaging.

The laminated film and food packaging bag of the present invention have been described above, but the present invention is not limited to the foregoing embodiments.

For example, in the laminated film and food packaging bag of the present invention, a part of the configuration may be replaced with another configuration that exhibits the same function, or any configuration may be added.

[Example]

Next, the present invention will be described in more detail with examples and comparative examples. Below, unless otherwise specifically stated, "parts" and "%" are quality standards.

1. Fabrication of laminated film (Example 1)

First, the following resins were used to prepare the surface layer, intermediate layer, and sealing layer forming materials.

Next, each of these resin mixtures was supplied to three extruders for co-extrusion to form a laminated film composed of three layers including a surface layer/intermediate layer/sealing layer. In addition, the average thickness of the surface layer was 7 μm, the average thickness of the intermediate layer was 18 μm, and the average thickness of the sealing layer was 5 μm. Therefore, the average thickness of the entire laminated film is 30 μm.

Thereafter, on the surface of the obtained transparent laminated film (surface layer), corona discharge treatment was performed so that the surface energy became 33 mN/m.

[Formation material of surface layer]

‧Propylene-ethylene random copolymer (COPP(1)): 55 copies

Ethylene content: 2.0%

Density: 0.90g/cm ³

Melt flow rate (MFR): 6.0g/10 minutes

Melting point: 140°C

‧Propylene-ethylene-1-butene terpolymer: 35 parts

Density: 0.90g/cm ³

MFR: 5.4g/10 minutes (190°C, 21.18N)

‧Crystalline ethylene-1-butene copolymer: 10 parts

Density: 0.88g/cm ³

MFR: 4.0g/10 minutes

[Forming material of intermediate layer]

‧Propylene Single Polymer (HOPP): 58 copies

Density: 0.90g/cm ³

MFR: 7.5g/10 minutes

‧Propylene-ethylene random copolymer (COPP(2)): 15 copies

Ethylene content: 5.2%

Density: 0.90g/cm ³

MFR: 5.4g/10 minutes

‧Straight-chain low-density polyethylene (LLDPE): 10 servings

Density: 0.905g/cm ³

MFR: 4.0g/10 minutes

‧Straight-chain low-density polyethylene derived from sugar cane (biological LLDPE (2)): 17 servings

Product name: Made by Braskem, "SLH218"

Density: 0.916g/cm ³

MFR: 2.3g/10 minutes

[Sealing layer forming material]

‧COPP(2): 70 copies

‧Propylene-1-butene random copolymer (COPP(3)): 30 copies

Density: 0.90g/cm ³

MFR: 4.0g/10 minutes

(Example 2)

A laminated film was obtained in the same manner as in Example 1 except that the composition of the intermediate layer forming material was changed to the following.

‧HOPP: 58 copies

‧COPP(2): 15 copies

‧LLDPE: 10 copies

‧Straight-chain low-density polyethylene (biological LLDPE (1)) derived from sugar cane: 17 servings

Product name: Made by Braskem, "SLL118"

Density: 0.918g/cm ³

MFR: 1.0g/10 minutes

(Example 3)

A laminated film was obtained in the same manner as in Example 1 except that the composition of the intermediate layer forming material was changed to the following.

‧HOPP: 65 copies

‧COPP(2): 15 copies

‧LLDPE: 10 copies

‧Bio LLDPE (2): 10 copies

(Example 4)

A laminated film was obtained in the same manner as in Example 1 except that the composition of the intermediate layer forming material was changed to the following.

HOPP: 60 parts, COPP(2): 15 parts, LLDPE: 10 parts, biological LLDPE(2): 15 parts

(Example 5)

A laminated film was obtained in the same manner as in Example 1 except that the composition of the intermediate layer forming material was changed to the following.

HOPP: 50 parts, COPP(2): 15 parts, LLDPE: 10 parts, biological LLDPE(2): 25 parts

(Example 6)

A laminated film was obtained in the same manner as in Example 1 except that the composition of the intermediate layer forming material was changed to the following.

HOPP: 40 parts, COPP (2): 15 parts, LLDPE: 10 parts, biological LLDPE (2): 35 parts

(Comparative example 1)

A laminated film was obtained in the same manner as in Example 1 except that the composition of the intermediate layer forming material was changed to the following.

‧HOPP: 58 copies

‧COPP(2): 15 copies

‧LLDPE: 10 copies

‧Straight-chain low-density polyethylene (biological LLDPE(3)) derived from sugar cane: 17 servings

Product name: Made by Braskem, "SLL318"

Density: 0.918g/cm ³

MFR: 2.7g/10 minutes

(Comparative example 2)

A laminated film was obtained in the same manner as in Example 1 except that the composition of the intermediate layer forming material was changed to the following.

HOPP: 50 parts, COPP (2): 15 parts, LLDPE: 10 parts, biological LLDPE (3): 25 parts

2. Measurement and evaluation

The laminated films obtained in Examples and Comparative Examples were used to perform the following measurements and evaluations.

[Measurement of rigidity]

Based on ASTM D 882-12, using a Tensilon tensile tester (manufactured by A&D Co., Ltd.), the 1% tangent modulus at 23° C. of the laminated film obtained in Examples and Comparative Examples was measured.

In addition, the measurement is performed in the extrusion direction (hereinafter referred to as "MD direction") at the time of film production.

[Measurement of Transparency]

Based on JIS K 7105: 1987, the haze of the laminated film obtained by the Example and the comparative example was measured using a haze meter (made by Nippon Denshoku Industries Co., Ltd.).

Transparency was evaluated according to the following criteria.

<evaluation criteria>

◎: The turbidity is 4.5% or less.

○: The turbidity exceeds 4.5% and is 5.0% or less.

○~△: The turbidity exceeds 5.0% and is 5.5% or less.

△: The turbidity exceeds 5.5% and is 6.0% or less.

×: The turbidity exceeds 6.0%.

[Evaluation of suitability for bag making]

The sealing layer of the laminated film obtained in Examples and Comparative Examples was set to the inner side, and the laminated film was folded in half, gusset at the bottom, and fused and sealed at a sealing portion temperature (bag making temperature) of 300°C to make a bag ( Bag making machine: "HK-40V" manufactured by Totani Technical Research Co., Ltd., bag making speed: 120 pieces/minute). By this, a bottom gusset bag (length: 345 mm (side edge portion: 245 mm, gusset portion: 60 mm), width 235 mm) was produced, and the suitability of the bag was evaluated. In addition, 300 pieces were used as a group, aligned into a bundle, and the alignment was evaluated.

<evaluation criteria>

○: Even at a bag-making speed of 120 shots (shot), the laminated film can keep up, and there is no problem with the alignment.

△: Even at a bag-making speed of 120 shots, the laminated film can keep up, but part of the alignment is problematic.

×: There is a laminated film that cannot keep up with the 120-shot (shot) bag-making speed, and the alignment is poor.

[Determination of fuse seal strength]

Using the laminated films obtained in Examples and Comparative Examples, the bottom gusset bags were produced in the same manner as the above-mentioned evaluation of the suitability of bag-making.

From the center of the gussets of the five bottom gusset bags obtained, and the center of the side edges other than the gussets, one piece each was cut to a length of 70 mm so that the fuse seal portion became the center in the longitudinal direction , Test pieces with a width of 15 mm (2 pieces per bag), a total of 10 pieces. Then, each test piece was peeled using a Tensilon tensile tester (manufactured by A&D Co., Ltd.) under the conditions of 23° C. and a tensile speed of 300 mm/min. Let the maximum load measured at this time be the fuse seal strength.

<evaluation criteria>

◎: The fuse seal strength of the gusset part and the side part is 16N/15mm or more.

○: The fuse seal strength of the gusset portion and the side portion is 13 N/15 mm or more and less than 16 N/15 mm.

×: At least one of the gusset portion and the side edge portion has a fuse seal strength of less than 13N/15mm.

[Measurement of heat seal strength]

Using the laminated films obtained in Examples and Comparative Examples, the bottom gusset bags were produced in the same manner as in the evaluation of the suitability of the above-mentioned bags. Using a heat sealer (manufactured by TESTER SANGYO Co., Ltd., pressure: 0.2 MPa, time: 1 second, sealing temperature: upper sealing rod 95°C, lower sealing rod 50°C, sealing rod shape: 300m×10mm flat surface), place The portion of the bottom gusset bag opening 50 mm down from the obtained portion was heat-sealed parallel to the opening.

From the obtained five heat-sealed portions of the bottom gusset bags so that the heat-sealed portion becomes the center portion in the width direction, two test pieces each having a length of 70 mm and a width of 15 mm were cut out (two pieces per bag ), a total of 10 tablets. Then, each test piece was peeled using a Tensilon tensile tester (manufactured by A&D Co., Ltd.) under the conditions of 23°C and a tensile speed of 300 mm/min. Let the maximum load measured at this time be the heat seal strength.

<evaluation criteria>

○: The heat seal strengths are all less than 5N/15mm, and no film breakage occurs at the time of peeling.

×: The heat seal strength was 5 N/15 mm or more, or the film was broken when peeling off.

[Measurement of impact strength]

After the laminated films obtained in Examples and Comparative Examples were kept in a constant temperature chamber set at 0°C for 6 hours, the impact strength according to the film impact method was measured using a spherical metallic impact head with a diameter of 1.5 inches.

<evaluation criteria>

○: Impact strength is 0.15J or more.

△: Impact strength is 0.10J or more and less than 0.15J.

×: The impact strength is less than 0.10J.

The measurement results and evaluation results are shown in Table 1 below.

It is clear from Table 1 that the laminated film of the present invention obtained by the examples has suitable heat sealability, impact resistance, and high transparency.

Claims (15)

A laminated film comprising a surface layer (A), an intermediate layer (B) and a sealing layer (C), characterized in that the surface layer (A), the intermediate layer (B) and the sealing layer (C) Each contains a propylene-based resin, the intermediate layer (B) further contains a plant-derived polyethylene (b1), and the melt flow rate of the polyethylene (b1) is 2.5 g/10 minutes or less. The laminated film according to claim 1, wherein the aforementioned polyethylene (b1) is a linear low-density polyethylene. The laminated film according to claim 1 or 2, wherein the content of the polyethylene (b1) in the resin component contained in the intermediate layer (B) is 35% by mass or less. The laminated film according to any one of claims 1 to 3, wherein the intermediate layer (B) further contains 5 to 20% by mass of polyethylene derived from fossil fuel in the resin component contained in the intermediate layer (B) ( b2). The laminated film according to claim 4, wherein the aforementioned polyethylene (b2) is a linear low-density polyethylene. The laminated film according to claim 4 or 5, wherein the melt flow rate of the aforementioned polyethylene (b2) is 2 to 10 g/10 minutes. The laminated film according to any one of claims 1 to 6, wherein the content of the propylene-based resin in the resin component contained in the intermediate layer (B) is 50 to 90% by mass. The laminated film according to any one of claims 1 to 7, wherein the propylene-based resin of the intermediate layer (B) contains at least one of a propylene homopolymer and a propylene-α-olefin random copolymer. The laminated film according to any one of claims 1 to 8, wherein the content of the propylene-based resin in the resin component contained in each of the surface layer (A) and the sealing layer (C) is 50% by mass or more. The laminated film according to any one of claims 1 to 9, wherein the propylene-based resin for each of the surface layer (A) and the sealing layer (C) contains a propylene-α-olefin random copolymer. The laminated film according to any one of claims 1 to 10, wherein, in the thickness of the laminated film, the proportion of the surface layer (A) is 10 to 35%, and the proportion of the intermediate layer (B) is 45 to 85%, the proportion of the aforementioned sealing layer (C) is 5-20%. The laminated film according to any one of claims 1 to 11, wherein the average thickness of the laminated film is 25 to 50 μm. A food packaging bag characterized by using the laminated film according to any one of claims 1 to 12. The food packaging bag according to claim 13 has a gusset. For food packaging bags of claim 13 or 14, it is used for bread packaging.