JPWO2019230417A1 - Laminated film and food packaging bag - Google Patents

Abstract

The laminated film of the present invention is a laminated film in which a surface layer (A), an intermediate layer (B) and a seal layer (C) are laminated, and the surface layer (A), the intermediate layer (B) and the seal layer (C). ) Each contain 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. Thus, it is possible to obtain an environment-friendly film in which the transparency is small even if the content thereof is changed while maintaining the high transparency.

Description

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

In recent years, for the purpose of reducing the environmental load, it has been considered to replace a part of the material constituting the resin film used for the packaging material with a resin derived from fossil fuel such as petroleum, to a resin derived from a plant (for example, patents References 1 and 2).
Although plant-derived resins are highly environmentally friendly, they often exhibit properties different from fossil fuel-derived resins. Therefore, if a part of the material forming the resin film is simply replaced with a plant-derived resin, the desired characteristics of the resin film may not be obtained.

JP 2012-167172 A JP, 2013-151623, A

In particular, in a heat-sealable resin film (laminated film) mainly composed of propylene-based resin, when plant-derived polyethylene was used, heat-sealability, impact resistance and transparency were sometimes lowered. ..

The problem to be solved by the present invention is to use a laminated film having high transparency while having suitable heat-sealing properties and impact resistance in a film structure mainly composed of a propylene-based resin, and such a laminated film ( The purpose is to provide food packaging bags that have been made into bags.

The present invention is a laminated film in which a surface layer (A), an intermediate layer (B) and a seal layer (C) are laminated, wherein the surface layer (A), the intermediate layer (B) and the seal layer (C). ) Each contain 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 above problem is solved by a certain laminated film.

The laminated film of the present invention, in a film structure mainly composed of propylene resin, by using polyethylene of plant origin having a predetermined melt flow rate in combination, while maintaining high transparency, the content can be changed. Can be an environment-friendly film with a small change in transparency. Moreover, the laminated film of the present invention can be suitably used for packaging food such as bread.

Hereinafter, the laminated film and the food packaging bag of the present invention will be described in detail based on preferred embodiments.
The laminated film of the present invention has at least the surface layer (A), the intermediate layer (B) and the seal layer (C), one surface layer being the surface layer (A) and the other surface layer being the seal layer (C). ing.
In the present invention, the surface layer (A), the intermediate layer (B) and the seal layer (C) each contain a propylene-based resin, and the intermediate layer (B) further comprises a plant-derived polyethylene (b1) (hereinafter, "Biopolyethylene (b1)").

The configurations of the layers (A) to (C) will be sequentially described below.
[Surface layer (A)]
The surface layer (A) is a layer that constitutes a surface layer when the laminated film is formed into a food packaging bag, and functions as a printing layer on which printing is performed.
The surface layer (A) contains a propylene resin.

The content of the propylene-based resin in the resin component contained in the surface layer (A) is preferably 50% by mass or more because it is easy to impart suitable fusing sealability and bag-making suitability to the laminated film. It is preferably 70% by mass or more, more preferably 80% by mass or more, and particularly preferably 85% by mass or more. Further, the resin component contained in the surface layer (A) may substantially contain only a propylene resin.

As the propylene-based resin, for example, propylene homopolymer, propylene-α-olefin copolymer (propylene-α-olefin random copolymer, propylene-α-olefin block copolymer) and 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 further preferably 6% by mass. In addition, the α-olefin content is preferably 2% by mass or more, more preferably 3% by mass or more, and further preferably 4% by mass, because suitable impact resistance is easily imparted to the laminated film. It is more preferable that the above is satisfied.

Since the laminated film of the present invention is a film having high transparency (transparent film), a propylene-α-olefin random copolymer can be preferably used as the propylene-based resin.
Examples of the propylene-α-olefin random copolymer include a propylene-ethylene random copolymer, a propylene-1-butene random copolymer, a propylene-ethylene-1-butene random copolymer, and the like. These may be used alone or in combination of two or more. Above all, it is preferable to use a propylene-ethylene random copolymer as the propylene-α-olefin random copolymer, since suitable transparency can be easily imparted 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, and preferably 3 g/10 minutes or more. It is more preferable that the amount is 5 g/10 minutes or more. Further, 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 12 g/10 minutes or less. More preferable.
In addition, in this specification, unless otherwise specified, the MFR is measured under the measurement conditions of a temperature of 230° C. and a load of 21.18 N, in accordance with JIS K 7210:1999.

Propylene - ethylene random copolymer density of the polymer is preferably about 0.88~0.905g / cm ^3, more preferably 0.89~0.9g / cm ³ order.
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 fusing seal blade during bag making. Further, at the time of fusing and sealing at the time of bag making, it is necessary to form a sufficient fusing ball in order to develop a fusing and sealing property in the laminated film. Therefore, the melting point is preferably 150° C. or lower, and 145° C. or lower. Is more preferable.

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

In addition, since it is easy to form a sufficient fusing ball at the time of fusing and sealing, a propylene-1-butene random copolymer having a lower melting point or a propylene-ethylene-1-butene random copolymer having a lower melting point is used as a propylene-ethylene random copolymer. It is also preferable to use it in combination. Among them, a propylene-ethylene-1-butene random copolymer (propylene-ethylene-1-butene terpolymer) can be particularly preferably used.

The ethylene content and the 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 more preferably 10% by mass. Is more preferable. In addition, the ethylene content and the 1-butene content are each preferably 0.5% by mass or more, and more preferably 1.5% by mass or more, because suitable low-temperature sealing properties are easily imparted to the laminated film. It is more preferable that the content is 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, and 3.0 g/10 minutes or more. Is more preferable, and 5.0 g/10 minutes or more is further preferable. Further, 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 further preferably 12 g/10 minutes or less. ..

Propylene - ethylene-1 is the density of butene random copolymer, is preferably about 0.88~0.905g / cm ^3, more preferably 0.89~0.9g / cm ³ order.
The melting point of the propylene-ethylene-1-butene random copolymer is preferably 105° C. or higher, more preferably 110° C. or higher, from the viewpoint of preventing adhesion to the fusing seal blade during bag making. Further, at the time of fusing and sealing at the time of bag making, it is necessary to form a sufficient fusing ball in order to develop a fusing and sealing property in the laminated film, so the melting point is preferably 145° C. or lower, and 140° C. or lower. Is more preferable.

The content of the propylene-ethylene-1-butene random copolymer in the resin component contained in the surface layer (A) is 15% by mass or more because it is easy to impart suitable fusion-cutting sealability to the laminated film. Is preferable, 25% by mass or more is more preferable, and 30% by mass or more is further preferable. The content thereof is preferably 55% by mass or less, more preferably 45% by mass or less, and further preferably 40% by mass or less.

For the surface layer (A), various olefin-based resins used in packaging films other than the above-mentioned propylene-based resin may be used. Examples of such an olefin resin include an ethylene homopolymer, an ethylene copolymer, and an ionomer of an ethylene-(meth)acrylic acid copolymer. These may be used alone or in combination of two or more.
Examples of the ethylene-based homopolymer include ultra-low density polyethylene (VLDPE), linear low-density polyethylene (LLDPE), and low-density polyethylene (LDPE).

Examples of the ethylene copolymer include ethylene-1-butene copolymer, ethylene-vinyl acetate copolymer (EVA), ethylene-methyl methacrylate 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) and the like.
The content of these olefinic resins in the resin component contained in the surface layer (A) is preferably 20% by mass or less.

Among them, as an olefin resin other than the propylene resin, an ethylene-1-butene copolymer ( A crystalline ethylene-1-butene copolymer) can be preferably used. The ethylene-1-butene copolymer can be used particularly preferably when the laminated film is used as a transparent film.
Since it is easy to impart suitable low temperature sealing properties to the laminated film, the content of the ethylene-1-butene copolymer in the resin component contained in the surface layer (A) is about 1 to 20% by mass. It is preferably present, and more preferably about 5 to 15% by 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 minutes or more, and more preferably 2 g/10 minutes or more. It is more preferably 3 g/10 minutes or more. Further, 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 further preferably 10 g/10 minutes or less. ..
The density of the ethylene-1-butene copolymer is preferably about 0.87~0.9g / cm ^3, more preferably 0.875~0.895g / cm ³ order.

In addition, a plant-derived resin may be used in combination in the surface layer (A). When the usage ratio of the plant-derived resin contained in the laminated film (hereinafter, also referred to as “bio-degree”) is increased, the content of the plant-derived resin in the resin component contained in the surface layer (A) is adjusted. It is preferably 10% by mass or more, and more preferably 20 to 50% by mass.
On the other hand, when importance is attached to various properties such as heat-sealing property, fusion-sealing property, and impact resistance of the laminated film, the content of the plant-derived resin in the resin component contained in the surface layer (A) is 10 mass. %, preferably less than 5% by mass, and 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 additive include an antioxidant, a weather resistance stabilizer, an antistatic agent, an antifogging agent, an antiblocking agent, a lubricant, a nucleating agent, a pigment and the like.

The surface roughness (Ra) defined by JIS B 0601:2001 on the surface of the surface layer (A) is preferably about 0.2 to 1, and more preferably about 0.3 to 0.7. preferable. By adjusting the surface roughness (Ra) within the above range, the additive amount of other additives (for example, a slip agent, an anti-blocking agent, etc.) is reduced, or even if they are not used in combination, the surface slipperiness is excellent. A laminated film is obtained. For this reason, in addition to improving bag making speed, improve the workability when packing the contents with an automatic wrapping machine, etc. by associating after bag making, improving and improving packing efficiency. Can also

The friction coefficient of the surface of the surface layer (A) specified in ASTM D 1894-95 is preferably about 0.05 to 0.7, more preferably about 0.07 to 0.6, More preferably, it is about 0.1 to 0.5. By setting the friction coefficient within the above range, it becomes easy to improve the film feeding property during packaging, the aligning property after bag making, the packaging workability, and the like. Further, it becomes easy to suitably prevent the film from breaking when bound by the closure. The friction coefficient can be adjusted by appropriately adding additives such as a lubricant and an anti-blocking agent according to the resin component used in the surface layer (A).

[Intermediate layer (B)]
The intermediate layer (B) is a layer having a function of imparting to the laminated film the characteristics required when making a food packaging bag and the characteristics required as a food packaging bag.
The intermediate layer (B) contains a propylene resin and further contains biopolyethylene (b1). The present invention is characterized in that the biopolyethylene (b1) has an MFR of 2.5 g/10 minutes or less.
By containing a propylene-based resin, it is possible to impart favorable heat resistance and fusing sealability in a wide temperature range to the laminated film, as well as suitable impact resistance and bag breaking resistance. ..

Further, by containing the biopolyethylene (b1) having an MFR of 2.5 g/10 minutes or less, high transparency of the laminated film can be maintained. Further, even if the content of the biopolyethylene (b1) is changed, the change in transparency of the laminated film can be suppressed.
Here, the transparency of the laminated film can be represented by the value (unit: %) of haze (haze).
The degree of change in the transparency of the laminated film due to the change in the content of the biopolyethylene (b1) is preferably as follows. Generally, when the content of the biopolyethylene (b1) in the resin component contained in the intermediate layer (B) is increased, the transparency of the laminated film tends to decrease (the haze 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 haze of the laminated film is A (%), and the content is 35% by mass. When the value of haze at that time is B (%), the rate of change represented by (BA)/(35-10) is preferably 0.1 or less, and 0.08 or less. It is more preferable, and it is further preferable that it is 0.06 or less. If the rate of change is in this range, it can be said that the variation in transparency of the laminated film is sufficiently small.
Further, by using the bio-polyethylene (b1), it is possible to increase the bio degree of the laminated film, which contributes to the reduction of carbon dioxide emission and the environmental friendliness.

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

The bio-polyethylene (b1) can be produced in the same manner as in the production method of polyethylene using a petroleum-derived monomer that produces a monomer (ethylene) from plants such as sugar cane, corn and beet as a raw material.
The production method is not particularly limited, but a known method can be used, and examples thereof include a method using a Ziegler-Natta catalyst or a metallocene catalyst.

Specifically, a titanium-containing compound itself or a catalyst system using a carrier-supported catalyst in which a titanium-containing compound is supported on a carrier such as a magnesium compound as a main catalyst and an organoaluminum compound as a co-catalyst, propylene alone or propylene A method of adding a desired α-olefin (for example, ethylene or the like) to carry out polymerization can be preferably used.
For this polymerization, any process such as a slurry polymerization method, a solution polymerization method and a gas phase polymerization method may be used.

A homogeneous catalyst may be used for the polymerization. As the homogeneous catalyst, a catalyst composed of a vanadium compound and an organoaluminum compound which have been conventionally used, or one or two of a cyclopentadienyl group, a substituted cyclopentadienyl group, an indenyl group, a substituted indenyl group and the like are used. Zirconium, titanium, hafnium and other transition metal compounds having a ligand, and metallocene catalysts comprising a transition metal compound in which the ligand is geometrically controlled and a cocatalyst such as aluminoxane or ionic compound. To be
The metallocene catalyst may be used in combination with an organoaluminum compound, if necessary, in a homogeneous polymerization in the presence of a solvent, a slurry polymerization method, a gas phase polymerization method, or the like.

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

The linear low-density polyethylene has a density of preferably 0.925 g/cm ³ or less, more preferably 0.92 g/cm ³ or less. By setting the density of the linear low-density polyethylene within the above range, it becomes easy for the laminated film to have suitable fusing sealability, high impact resistance and bag breaking resistance.
Examples of commercially available products of such biopolyethylene (b1) include SLL218, SLL318, SLH218, SBC818, SPB208, SEB853 manufactured by Braschem.

The content of the bio-polyethylene (b1) in the resin component contained in the intermediate layer (B) has a high environmental load reducing effect, and has high transparency, suitable rigidity and impact resistance for the laminated film. Since it is easy to add the following, it is preferably 35% by mass or less, more preferably 25% by mass or less, and further preferably about 5 to 20% by mass.

The intermediate layer (B) may further contain fossil fuel-derived polyethylene (b2). Since the propylene-based resin used in the intermediate layer (B) is also a resin derived from fossil fuel, the polyethylene (b2) has a high affinity (compatibility) with the propylene-based resin. Therefore, when the bio low density polyethylene (b1) is used in combination, the presence of the polyethylene (b2) facilitates the uniform mixing of the bio low density polyethylene (b1) with the propylene resin. As a result, the characteristics of the intermediate layer (B) can be made uniform.

Examples of polyethylene (b2) include ethylene-based homopolymers, ethylene-based copolymers, and ionomers of ethylene-(meth)acrylic acid copolymers. These may be used alone or in combination of two or more.
Examples of the ethylene homopolymer include linear low-density polyethylene (LLDPE), linear medium-density polyethylene (LMDPE), linear high-density polyethylene (LHDPE), low-density polyethylene (LDPE), and medium-density polyethylene. (MDPE) and high density polyethylene (HDPE).

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

Especially, as the polyethylene (b2), linear low-density polyethylene is preferable. 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 the polyethylene (b2) having such an MFR, it is easy to improve the film-forming property of the laminated film and the dispersibility of the polyethylene (b2) in the intermediate layer (B) is good. It becomes easy to give uniform characteristics.

Density polyethylene (b2) is preferably at 0.915 g / cm ³ or less, more preferably 0.91 g / cm ³ or less, and more preferably 0.906 g / cm ³ or less. By using the polyethylene (b2) having such a density, it becomes easy to impart suitable fusing sealing property, high impact resistance and bag breaking resistance to the laminated film.
The content of polyethylene (b2) in the resin component contained in the intermediate layer (B) is suitable for the laminated film while maintaining good film-forming property and moldability of the laminated film. , And is appropriately set in consideration of appropriately imparting bag-making processing suitability and the like. Specifically, the content of polyethylene (b2) is preferably about 5 to 20% by mass, and more preferably about 5 to 15% by mass.

The content of the propylene-based resin in the resin component contained in the intermediate layer (B) is about 50 to 90% by mass because it is easy to impart suitable fusion-cutting sealability and bag-making suitability to the laminated film. It is preferably about 60 to 85% by mass, more preferably about 70 to 80% by mass.

The propylene-based resin of the intermediate layer (B) includes the same propylene-based resin as the surface layer (A), for example, propylene homopolymer, propylene-α-olefin copolymer (propylene-α-olefin random copolymer, Propylene-α-olefin block copolymer) and the like can be used.
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 3 g/ More preferably, it is 10 minutes or longer. Further, 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 10 g/10 minutes or less. More preferable.

The density of the propylene homopolymer is preferably about 0.88~0.92g / cm ^3, more preferably 0.885~0.915g / cm ³ order.
The melting point of the propylene homopolymer is preferably 145° C. or higher, and more preferably 150° C. or higher, from the viewpoint of sufficiently maintaining the processability of the laminated film for bag making and the like.

The content of the propylene homopolymer in the resin component contained in the intermediate layer (B) is preferably about 35% by mass, because suitable rigidity and transparency are easily imparted to the laminated film, It is more preferably 45% by mass or more, and further preferably 55% by mass or more. Further, since it is easy to impart suitable impact resistance to the laminated film, it is preferably 90% by mass or less, more preferably 85% by mass or less, and further preferably 80% by mass or less. preferable.

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 minutes or more, and preferably 3 g/10 minutes or more. More preferably, it is more preferably 5 g/10 minutes or more. Further, 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 further preferably 12 g/10 minutes or less. ..

The density of the propylene -α- olefin random copolymer is preferably about 0.88~0.905g / cm ^3, more preferably 0.89~0.9g / cm ³ order.
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 fusing seal blade during bag making. Further, at the time of fusing and sealing during bag making, it is necessary to form a sufficient fusing and fusing ball in order to develop a suitable fusing and sealing property for the laminated film. Therefore, the melting point is preferably 150° C. or lower, 145 It is more preferable that the temperature is not higher than °C.

The α-olefin content in the propylene-α-olefin random copolymer is not particularly limited, but is preferably about 1 to 20% by mass, more preferably about 1.5 to 15% by mass.
Examples of the propylene-α-olefin random copolymer include a propylene-ethylene random copolymer, a propylene-1-butene random copolymer, a propylene-ethylene-1-butene random copolymer, and the like. These may be used alone or in combination of two or more. Above all, it is preferable to use a propylene-ethylene random copolymer as the propylene-α-olefin random copolymer, since suitable transparency can be easily imparted to the laminated film.

By including the propylene-ethylene random copolymer in the propylene-based resin, the affinity (compatibility) between the propylene-based resin and the biopolyethylene (b1) and/or the polyethylene (b2) can be increased.
Since the content of the propylene-α-olefin random copolymer in the resin component contained in the intermediate layer (B) easily imparts suitable bag-making suitability and bag-breaking resistance to the laminated film, The amount 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 a propylene-based resin and biopolyethylene (b1), and may contain various additives as long as the effects of the present invention are not impaired. Examples of the additive include an antioxidant, a weather resistance stabilizer, an antistatic agent, an antifogging agent, an antiblocking agent, a lubricant, a nucleating agent, a pigment and the like.

[Seal layer (C)]
The seal layer (C) is a layer used for adhering the seal layers (C) of the laminated film to each other or adhering the laminated film to another container or film.
The seal layer (C) contains a propylene resin. By containing the propylene resin, high adhesion between the seal layer (C) and the intermediate layer (B) can be obtained.

The content of the propylene-based resin in the resin component contained in the seal layer (C) is preferably 50% by mass or more, and 70% by mass or more, since it is easy to give suitable sealing properties to the laminated film. More preferably, it is more preferably 90% by mass or more, and substantially 100% by mass.

In addition, the sealing layer (C) may be configured by appropriately selecting a resin type capable of obtaining a suitable sealing strength in accordance with a use mode and an object to be sealed.
For example, when the sealing layers (C) are sealed and used as a packaging bag, a propylene-based resin is a propylene-ethylene random copolymer or a propylene-1-butene random, from the viewpoint of obtaining an appropriate sealing strength. It is preferable to include a propylene-α-olefin random copolymer such as a copolymer and an α-olefin-propylene random copolymer such as a 1-butene-propylene random copolymer.

Among them, the propylene-based resin preferably contains a butene-based random copolymer such as a propylene-1-butene random copolymer and a 1-butene-propylene random copolymer. If a propylene-based resin containing such a butene-based random copolymer is used, it is easy to adjust the heat-sealing temperature and strength at the time of easy-opening sealing at low temperature, the heat-sealing temperature range is wide, and as an easy-opening seal. This is because it is easy to obtain an appropriate heat seal strength.

The 1-butene content in the butene-based random copolymer is preferably about 60 to 95 mol %, from the viewpoint of easily providing suitable sealing properties and blocking resistance to the laminated film, and 65 to 95. It is more preferably about mol%, further preferably about 70 to 90 mol%. In addition, the propylene content is preferably about 2 to 10 mol%, more preferably about 3 to 9 mol%, and more preferably 4 because the suitable low temperature sealing property is easily imparted to the laminated film. It is more preferably about 8 mol%.

The content of the butene-based random copolymer in the resin component contained in the seal layer (C) is preferably 50% by mass or less, more preferably 40% by mass or less, and 30% by mass or less. Is more preferable. The content thereof is preferably 10% by mass or more, more preferably 15% by mass or more. When the content of the butene-based random copolymer is set within the above range, suitable low temperature sealability, fusing sealability and tear resistance are easily imparted to the laminated film, and it is also advantageous for cost reduction. ..

It is preferable to use another propylene-α-olefin random copolymer in combination with the butene random copolymer.
The α-olefin content in the propylene-α-olefin random copolymer is not particularly limited, but is preferably about 1 to 20% by mass, more preferably about 1.5 to 15% by mass. Examples of the α-olefin include ethylene, 1-hexene, 4-methyl-1-pentene, 1-octene and the like.

Among them, as the propylene-α-olefin random copolymer, the same propylene-α-olefin random copolymer as in the intermediate layer (B) can be used.
In addition, the MFR of the propylene-α-olefin random copolymer is preferably about 0.5 to 20 g/10 minutes, and preferably about 2 to 10 g/10 minutes, because good moldability of the laminated film is easily obtained. Is more preferable.

The content of the other propylene-α-olefin random copolymer in the resin component contained in the sealing layer (C) is 90% by mass or less, since suitable low-temperature sealing property is easily imparted to the laminated film. Is preferable, and it is more preferable that it is 85 mass% or less. The content thereof is preferably 50% by mass or more, more preferably 60% by mass or more.

In particular, in the case of forming a packaging bag using a laminated film, in the case of providing an easily openable seal portion in which the seal layers (C) are heat-sealed, a butene-based random copolymer and a propylene-α-olefin random are used. It is preferable to use the copolymer together with the copolymer at a ratio such that the mass ratio represented by the butene-based random copolymer/propylene-α-olefin random copolymer is about 20/80 to 50/50.

The seal layer (C) may also contain a plant-derived polyolefin (for example, the plant-derived polyethylene (b1) as described above). From the viewpoint of improving the degree of biotechnology, the content of the plant-derived polyolefin in the resin component contained in the seal layer (C) is preferably 10% by mass or more, and more preferably about 20 to 50% by mass. preferable.
On the other hand, when importance is attached to properties such as fusing sealing property 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 more preferable that the content be substantially 0% by mass.

The seal layer (C) may be composed only of a resin containing a propylene-based resin, and may contain various additives as long as the effects of the present invention are not impaired. Examples of the additive include an antioxidant, a weather resistance stabilizer, an antistatic agent, an antifogging agent, an antiblocking agent, a lubricant, a nucleating agent, a pigment and the like.

The friction coefficient of the surface of the seal layer (C) specified by ASTM D 1894-95 is preferably about 0.01 to 0.4, more preferably about 0.02 to 0.35, More preferably, it is about 0.05 to 0.3. By setting the friction coefficient within the above range, it becomes easy to improve the film feeding property at the time of packaging and the workability of the packaging work by suppressing wrinkles and rise after bag making.

Further, when filling the contents such as bread with the contents rubbed against the inner surface of the laminated film (the surface of the seal layer (C)), the occurrence of scratches can be suppressed. Furthermore, abrasion resistance and tear resistance can be easily imparted to the laminated film, and film breakage can be suitably suppressed. The friction coefficient can be adjusted by appropriately adding additives such as a lubricant and an anti-blocking agent according to the resin component used in the seal layer (C).

[Laminated film]
The laminated film of the present invention is a laminated film in which the above surface layer (A), intermediate layer (B) and seal layer (C) are laminated, and the intermediate layer (B) has a melt flow rate of 2.5 g. /10 minutes or less of plant-derived polyethylene (b1) is contained. With this configuration, the laminated film of the present invention can achieve suitable heat sealability and impact resistance as well as suitable transparency even when biopolyethylene is contained in the film structure mainly composed of propylene resin.

The average thickness of the laminated film may be appropriately adjusted depending on the use and aspect of the packaging bag to be produced, but is 25 to 25 because it is easy to achieve both volume reduction and bag breakage during distribution. The thickness is preferably about 50 μm, more preferably 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 ratio 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 seal 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, more preferably about 1 to 10 μm.
The specific average thickness of the intermediate layer (B) is preferably about 5 to 35 μm, more preferably about 10 to 25 μm.
The specific average thickness of the seal layer (C) is preferably about 1 to 20 μm, more preferably about 5 to 10 μm.

Further, 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, from the viewpoint of improving environmental compatibility. More preferably, it is at least mass %.

The haze of the laminated film is preferably 6% or less, more preferably 5.5% or less, and 5.0% or less, because the contents to be packaged can be easily visually recognized. Is more preferable and 4.5% or less is particularly preferable. Even when the laminated film has such high transparency, the laminated film has suitable packaging suitability and is less likely to cause bag breakage such as tearing due to friction or rubbing between the content and the film.

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 a high haze in each layer, or to reduce the amount of the resin used 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 the laminated film of the present invention can easily obtain suitable scratch resistance and bag rupture resistance, its rigidity (MD) is preferably 450 MPa or more, more preferably 550 MPa or more, and 600 MPa or more. Is more preferable. In addition, the said rigidity measures the 1% tangent modulus at 23 degreeC of the obtained laminated film based on ASTM D882-12, using a Tensilon tensile tester (made by A&D Co., Ltd.).

The laminated film of the present invention is preferable to have an impact strength of 0.10 J or more, and preferably 0.15 J or more, since it is easy to suppress bag breakage and leakage of contents when used as a packaging material. Is more preferable. The impact strength is measured by a film impact method using a spherical metallic impact head having a diameter of 1.5 inches after holding the laminated film in a thermostatic chamber set at 0° C. for 6 hours.

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

As an example of a specific layer structure, a surface layer (A) in which an intermediate layer (B) is provided between the surface layer (A) and the seal layer (C)/intermediate layer (B)/seal layer (C) Or a four-layer structure of surface layer (A)/intermediate layer (B1)/intermediate layer (B2)/seal layer (C) in which the intermediate layer (B) is a laminate. Among them, a three-layer structure composed of the surface layer (A)/intermediate layer (B)/seal layer (C) is preferable because the characteristics of the laminated film can be easily adjusted and the laminated film can be easily manufactured.

The method for producing the laminated film is not particularly limited, but for example, a coextrusion method can be used. In the co-extrusion method, the resin or resin mixture used for each layer is melted by heating in separate extruders, laminated in a molten state by a method such as a co-extrusion multilayer die method or a feed block method, and then blown or T-die. -A laminated film is obtained by forming into a film by the chill roll method or the like.
According to the coextrusion method, it is possible to adjust the thickness ratio of each layer relatively freely, and it is possible to obtain a laminated film having excellent hygiene and cost performance.
Since the laminated film obtained by the above production method is obtained as a substantially non-stretched multilayer film, secondary forming such as deep drawing by vacuum forming is also possible.

It is also preferable to apply a surface treatment to the surface of the surface layer (A) in order to improve the adhesion (adhesion) of the printing ink. Examples of such surface treatment include corona discharge treatment, plasma treatment, chromic acid treatment, flame treatment, hot air treatment, surface oxidation treatment such as ozone/ultraviolet treatment, and surface unevenness treatment such as sandblast treatment. You can These treatments may be used alone or in combination of two or more. Among them, corona discharge treatment is suitable as the surface treatment.
Examples of the packaging material comprising the laminated film of the present invention include packaging bags, containers, lid materials for containers used for foods, chemicals, industrial parts, sundries, magazines and the like.

In the packaging bag, the sealing layers (C) of the laminated film are laminated and heat-sealed, or the surface layer (A) and the sealing layer (C) are superposed and heat-sealed to form the sealing layer (C). It is preferable that the inner side is formed in a bag shape.
For example, two laminated films are cut into a desired packaging bag size, they are stacked and heat-sealed on three sides to form a bag, and then the contents are opened from one side that is not heat-sealed. Can be used as a packaging bag by filling and heat-sealing the opening.
Furthermore, it is also possible to form a packaging bag by pulling out a roll-shaped laminated film with an automatic packaging machine, heat-sealing the overlapping ends by making it a cylindrical shape, and then heat-sealing the upper end and the lower end respectively. Is.

Further, in the case of a packaging bag for bread, a bag having a gusset portion (bottom gusset bag) can be obtained by folding and sealing the printing surface. Specifically, with the sealing layer (C) of the laminated film of the present invention inside the bag, a bottom gusset bag is formed by a bag making machine (eg, "HK-40V" manufactured by Totani Giken Co., Ltd.). To process.
The laminated film of the present invention exhibits suitable fusing and sealing properties and suitability for bag making, and thus can be particularly preferably used for making a bottom gusset bag.

The fusing seal strength of the side portion and bottom gusset portion (bottom portion of the bottom) of the bottom gusset bag is preferably 13 N/15 mm or more, more preferably 14 N/15 mm or more, and 14.5 N/15 mm or more. It is more preferable that the amount is 16 N/15 mm or more. The upper limit is not particularly limited, but is preferably 30 N/15 mm or less. The fusing seal strength can be set by adjusting the fusing seal temperature and the bag making speed during bag making.

The bottom gusset bag thus obtained is supplied to an automatic bread filling machine, and after filling bread, it is heat-sealed so as to be easily opened. The heat seal strength at this time is preferably less than 5 N/15 mm, more preferably 0.1 N/15 mm or more and less than 5 N/15 mm, and further preferably 0.2 N/15 mm or more and less than 4 N/15 mm. preferable.
Then, if necessary, the upper portion of the bag may be bound using a binding tool such as a plastic plate, tape, or string.

In the case of integrated packaging of various breads such as butter rolls, a horizontal pillow type automatic packaging machine (for example, "FW-3400αV type" manufactured by Fujikikai Co., Ltd.) has a seal layer (C) inside the bag. Then, the laminated film is supplied in the form of a roll. Since the laminated film of the present invention is excellent in heat sealing property and easy opening property in pillow packaging, it can be particularly preferably used for pillow packaging bags.

In the horizontal pillow type automatic wrapping machine, the sealing surfaces of the sealing layers (C) of the laminated film are superposed and heat-sealed to form a bag, and the bread is contained therein. The heat-sealing strength of the bottom portion and the back-applied portion of the pillow packaging bag by this packaging machine is preferably about 7.5 to 30 N/15 mm, and more preferably about 10 to 30 N/15 mm. The heat seal strength can be set by adjusting the heat seal temperature and the packaging speed.
Next, the upper part of the pillow packaging bag may be heat-sealed to form an easily-openable seal portion, and the vicinity thereof may be bound using a binding tool such as a plastic plate, tape, or string. When forming the easy-open seal portion, the heat seal strength thereof is preferably less than 5 N/15 mm, more preferably 0.1 N/15 mm or more and less than 5 N/15 mm, and 0.2 N/15 mm or more 4 N. More preferably, it is less than /15 mm.

It is also possible to form a packaging bag, a container, or a lid of the container by stacking and heat-sealing the seal layer (C) and another heat-sealable film.
In this case, a film having a relatively low mechanical strength made of LDPE, EVA, polypropylene or the like can be used as another film. Further, as another film, a film composed of LDPE, EVA, polypropylene or the like, a stretched film having relatively good tearability (for example, a biaxially oriented polyethylene terephthalate film (OPET), a biaxially oriented polypropylene film (OPP). It is also possible to use a laminated film obtained by laminating the above) and the like).

As described above, since the laminated film of the present invention exhibits suitable impact resistance and bag breaking 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 for food packaging applications that are often packaged and distributed at low temperatures.

Among them, the laminated film of the present invention, when applied to bread packaging such as loaf bread and confectionery bread in which a binding tool (closure) having a sharp tip portion or a hook portion is used, a bag breakage at the time of binding is unlikely to occur, and Also, pinholes and tears are unlikely to occur even if they come into contact with the binder or the transport container during transfer. Also, pinholes and tears due to friction between the food as the content and the inner surface of the film (sealing surface), friction with the mixed plastic tray, piercing, etc. are unlikely to occur. Furthermore, since the laminated film of the present invention can secure a suitable fusing 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 the food packaging bag of the present invention have been described above, but the present invention is not limited to the above-described embodiments.
For example, in the laminated film and the food packaging bag of the present invention, a part of the configuration thereof may be replaced with another configuration exhibiting the same function, or any configuration may be added.

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. Hereinafter, "parts" and "%" are based on mass unless otherwise specified.
1. Preparation of laminated film (Example 1)
First, the materials for forming the surface layer, the intermediate layer and the seal layer were prepared using the following resins.

Next, these resin mixtures were supplied to each of three extruders and coextruded to form a laminated film having a three-layer structure of surface layer/intermediate layer/seal layer. 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 seal layer was 5 μm. Therefore, the average thickness of the entire laminated film is 30 μm.
Then, the surface of the obtained transparent laminated film (surface layer) was subjected to corona discharge treatment so that the surface energy was 33 mN/m.

[Material for forming surface layer]
-Propylene-ethylene random copolymer (COPP(1)): 55 parts Ethylene content: 2.0%
Density: 0.90 g/cm ³
Melt flow rate (MFR): 6.0 g/10 minutes Melting point: 140°C
Propylene - Ethylene-1-butene terpolymer: 35 parts Density: 0.90 g / cm ³
MFR: 5.4g/10 minutes (190°C, 21.18N)
Crystalline ethylene-1-butene copolymer: 10 parts Density: 0.88 g / cm ³
MFR: 4.0 g/10 minutes

[Material for forming the intermediate layer]
Propylene homopolymers (HOPP): 58 parts Density: 0.90 g / cm ³
MFR: 7.5 g/10 minutes-Propylene-ethylene random copolymer (COPP(2)): 15 parts Ethylene content: 5.2%
Density: 0.90 g/cm ³
MFR: 5.4 g / 10 min, linear low density polyethylene (LLDPE): 10 parts Density: 0.905 g / cm ³
MFR: 4.0 g/10 minutes-Sugar cane-derived linear low-density polyethylene (Bio-LLDPE(2)): 17 parts Brand name: Braskem's "SLH218"
Density: 0.916 g/cm ³
MFR: 2.3g/10 minutes

[Seal layer forming material]
· COPP (2): 70 parts Propylene-1-butene random copolymer (COPP (3)): 30 parts Density: 0.90 g / cm ³
MFR: 4.0 g/10 minutes

(Example 2)
A laminated film was obtained in the same manner as in Example 1 except that the composition of the material for forming the intermediate layer was changed to the following.
・HOPP: 58 parts ・COPP(2): 15 parts ・LLDPE: 10 parts ・Sugar cane-derived linear low-density polyethylene (Bio-LLDPE(1)): 17 parts Brand name: "SLL118" manufactured by Braskem Co.
Density: 0.918 g/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 material for forming the intermediate layer was changed to the following.
・HOPP: 65 parts ・COPP(2): 15 parts ・LLDPE: 10 parts ・Bio-LLDPE(2): 10 parts

(Example 4)
A laminated film was obtained in the same manner as in Example 1 except that the composition of the material for forming the intermediate layer was changed to the following.
HOPP: 60 parts, COPP(2): 15 parts, LLDPE: 10 parts, Bio-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 material for forming the intermediate layer was changed to the following.
HOPP: 50 parts, COPP(2): 15 parts, LLDPE: 10 parts, Bio-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 material for forming the intermediate layer was changed to the following.
HOPP: 40 parts, COPP(2): 15 parts, LLDPE: 10 parts, Bio-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 material for forming the intermediate layer was changed to the following.
・HOPP: 58 parts ・COPP(2): 15 parts ・LLDPE: 10 parts ・Sugar cane-derived linear low-density polyethylene (Bio LLDPE(3)): 17 parts Brand name: "SLL318" manufactured by Braskem Co.
Density: 0.918 g/cm ³
MFR: 2.7 g/10 minutes

(Comparative example 2)
A laminated film was obtained in the same manner as in Example 1 except that the composition of the material for forming the intermediate layer was changed to the following.
HOPP: 50 parts, COPP(2): 15 parts, LLDPE: 10 parts, Bio-LLDPE(3): 25 parts

2. Measurement and Evaluation Using the laminated films obtained in Examples and Comparative Examples, the following measurements and evaluations were performed.

[Measurement of rigidity]
The 1% tangent modulus at 23° C. of the laminated films obtained in Examples and Comparative Examples was measured using a Tensilon tensile tester (manufactured by A&D Co., Ltd.) based on ASTM D882-12.
The measurement was carried out in the extrusion direction (hereinafter referred to as “MD direction”) during the film production.

[Measurement of transparency]
The haze of the laminated films obtained in Examples and Comparative Examples was measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd.) based on JIS K 7105:1987.
The transparency was evaluated according to the following criteria.

<Evaluation criteria>
⊚: The haze is 4.5% or less.
◯: Haze is more than 4.5% and 5.0% or less.
◯ to Δ: The haze is more than 5.0% and 5.5% or less.
Δ: Haze is more than 5.5% and 6.0% or less.
X: Haze is more than 6.0%.

[Evaluation of suitability for bag making]
With the sealing layer of the laminated film obtained in the examples and comparative examples inside, after half-folding the laminated film, a gusset was placed at the bottom, and fusion-sealing was performed at a sealing portion temperature (bag making temperature) of 300° C. Bags (bag making machine: "HK-40V" manufactured by Totani Giken Factory, bag making speed: 120 sheets/min) were used. Thereby, a bottom gusset bag (length: 345 mm (side portion: 245 mm, gusset portion: 60 mm), width 235 mm) was produced, and bag making suitability was evaluated. In addition, 300 sheets as one set were aligned and bundled to evaluate the alignment.

<Evaluation criteria>
◯: The laminated film follows up even at a bag-making speed of 120 shots, and there is no problem in alignment.
(Triangle|delta): Even if the bag-making speed of 120 shots is followed, a laminated|multilayer film will follow, but a part alignment property becomes a problem.
X: There is a laminated film that cannot follow the bag-making speed of 120 shots, and the alignment is poor.

[Measurement of fusing seal strength]
Using the laminated films obtained in Examples and Comparative Examples, a bottom gusset bag was produced in the same manner as the bag making suitability evaluation.
From the center of the gusset portion of the obtained bottom gusset bag 5 sheets, and the center of the side portion other than the gusset, one test piece each having a length of 70 mm and a width of 15 mm (2 pieces per bag), fusion-cut seal A total of 10 sheets were cut out so that the part was the central part in the length direction. Then, each test piece was peeled off with a Tensilon tensile tester (manufactured by A&D Co., Ltd.) under conditions of 23° C. and a pulling speed of 300 mm/min. The maximum load measured at this time was defined as the fusing seal strength.

<Evaluation criteria>
A: The fusing seal strengths of the gusset portion and the side portion are both 16 N/15 mm or more.
◯: The fusing seal strengths of the gusset portion and the side portion are both 13 N/15 mm or more and less than 16 N/15 mm.
X: The fusing seal strength of at least one of the gusset portion and the side portion is less than 13 N/15 mm.

[Measurement of heat seal strength]
Using the laminated films obtained in Examples and Comparative Examples, a bottom gusset bag was produced in the same manner as in the above evaluation of bag making suitability. A heat sealer (manufactured by Tester Sangyo Co., Ltd., pressure: 0.2 MPa, time: 1 second, sealing temperature: upper seal bar 95, 50 mm below the upper end of the opening of the obtained bottom gusset bag and parallel to the opening. C., lower seal bar 50.degree. C., seal bar shape: 300 m.times.10 mm flat surface).
From each of the five heat-sealed parts of the obtained bottom gusset bag, two test pieces each having a length of 70 mm and a width of 15 mm (two per one bag) were arranged so that the heat-sealed part became the center part in the width direction. , A total of 10 sheets were cut out. Then, each test piece was peeled off with a Tensilon tensile tester (manufactured by A&D Co., Ltd.) under conditions of 23° C. and a pulling speed of 300 mm/min. The maximum load measured at this time was taken as the heat seal strength.

<Evaluation criteria>
◯: The heat seal strengths were all less than 5 N/15 mm, and the film did not break when peeled off.
X: The heat seal strength was 5 N/15 mm or more, or the film was broken when peeled off.

[Measurement of impact strength]
The laminated films obtained in Examples and Comparative Examples were held in a thermostatic chamber set at 0° C. for 6 hours, and then impact strength was measured by a film impact method using a spherical metallic impact head having a diameter of 1.5 inches. Was measured.

<Evaluation criteria>
◯: Impact strength is 0.15 J or more.
B: Impact strength is 0.10 J or more and less than 0.15 J.
X: Impact strength is less than 0.10J.
The measurement results and evaluation results are shown in Table 1 below.

As is clear from Table 1, the laminated film of the present invention obtained in the examples had high transparency while having suitable heat sealability and impact resistance.

Claims (15)

A laminated film in which a surface layer (A), an intermediate layer (B) and a seal layer (C) are laminated,
The surface layer (A), the intermediate layer (B) and the seal layer (C) each contain a propylene-based resin,
The intermediate layer (B) further contains a plant-derived polyethylene (b1),
The melt flow rate of the polyethylene (b1) is 2.5 g/10 minutes or less, a laminated film. The laminated film according to claim 1, wherein the polyethylene (b1) is linear low-density polyethylene. Content of the said polyethylene (b1) in the resin component contained in the said intermediate|middle layer (B) is 35 mass% or less, The laminated|multilayer film of Claim 1 or 2. The said intermediate|middle layer (B) further contains 5-20 mass% of polyethylene (b2) derived from fossil fuel in the resin component contained in the said intermediate|middle layer (B). Laminated film. The laminated film according to claim 4, wherein the polyethylene (b2) is a linear low-density polyethylene. The laminated film according to claim 4 or 5, wherein the polyethylene (b2) has a melt flow rate of 2 to 10 g/10 minutes. Content of the said propylene resin in the resin component contained in the said intermediate|middle layer (B) is 50-90 mass %, The laminated|multilayer film in any one of Claims 1-6. The laminated film according to claim 1, 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. Content of the said propylene-type resin in the resin component contained in each of the said surface layer (A) and the said seal layer (C) is 50 mass% or more, The laminated|multilayer film in any one of Claims 1-8. .. The laminated film according to claim 1, wherein the propylene-based resin of each of the surface layer (A) and the seal layer (C) contains a propylene-α-olefin random copolymer. In the thickness of the laminated film, the surface layer (A) accounts for 10 to 35%, the intermediate layer (B) accounts for 45 to 85%, and the seal layer (C) accounts for 5%. It is 20%, The laminated film in any one of Claims 1-10. The laminated film according to claim 1, wherein the laminated film has an average thickness of 25 to 50 μm. A food packaging bag, comprising the laminated film according to claim 1. The food packaging bag according to claim 13, which has a gusset portion. The food packaging bag according to claim 13 or 14, which is used for bread packaging.