JPWO2019131168A1 - Laminated film and food packaging bag - Google Patents

Abstract

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) are propylene resin. And the intermediate layer (B) contains a plant-derived biomass polyethylene (b1), and the melt flow rate of the biomass polyethylene (b1) is 1.5 g/10 min or more. While applying the above, it is possible to realize not only suitable seal strength and impact resistance but also good fusing seal strength in a wide temperature range.

Description

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

In recent years, for the purpose of reducing the environmental load, a study to replace a part of the raw material of the resin film used for the packaging material from the resin containing the fossil fuel-derived component such as petroleum as the main component to the resin containing the plant-derived component as the main component Has been done.

As a resin film using a plant-derived resin, for example, a sealant film using a plant-derived linear low-density polyethylene as a sealant film laminated on a substrate and used for a laminated tube or a standing pouch (Patent Document 1). 2)), a lid material including a sealant layer using a plant-derived low-density biomass polyethylene, and a base material (Patent Document 3), and the like.

JP, 2016-145086, A JP 2012-167172 A JP, 2005-231870, A

Although plant-derived resins are highly environmentally friendly, they often show properties different from those derived from fossil fuels, and if simply replaced, heat-sealability, impact resistance, bag breakage resistance, etc. may have deteriorated. .. However, the resin film disclosed in the above document uses a resin derived from a plant, but when applied to applications such as standing pouches and lids, it is laminated with a laminate base material. No consideration is given to impact resistance, bag breakage resistance, etc. in a film structure having no laminated base material.

Further, in order to realize a suitable sealing property under manufacturing conditions according to various uses, it is necessary to have a fusing sealing property in order to apply it to various packaging forms such as when making a packaging bag with a fusing seal. Is desired to have good fusing seal strength over a wide temperature range.

Although the resin film disclosed in the above document is mainly composed of an ethylene-based resin, even in a film structure mainly composed of a propylene-based resin, it is desired to replace the fossil fuel-derived resin with a plant-derived resin. It is rare.

The problem to be solved by the present invention is to apply a plant-derived component in a film structure mainly composed of a propylene-based resin, have suitable seal strength and impact resistance, and have a good fusing seal in a wide temperature range. It is to provide a laminated film having strength.

In particular, to provide a laminated film having suitable seal strength and impact resistance even when it contains a large amount of plant-derived components, and further, in a film configuration mainly composed of a propylene-based resin, the resin plant-derived components are applied. At the same time, it is an object of the present invention to provide a laminated film that can realize suitable seal strength and impact resistance without using a laminated base material.

The present invention relates to 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). Contains a propylene-based resin, the intermediate layer (B) contains a plant-derived biomass polyethylene (b1), and the melt flow rate of the biomass polyethylene (b1) is 1.5 [g/10 min] or more. The film solves the above problems.

The laminated film of the present invention is suitable for use as various packaging materials because it has suitable seal strength and impact resistance while using a plant-derived resin, and has good fusing seal strength in a wide temperature range. it can. In particular, even if the laminated base material is not laminated, it has excellent impact resistance, and thus it can be suitably used as a packaging bag for pillow packaging or gusset packaging. In particular, since the laminated film of the present invention is excellent in fusing strength, it is suitable for use as a gusset packaging bag used for packaging food such as bread.

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 is the surface layer (A), and the other surface layer is the seal layer (C). A laminated film, wherein the surface layer (A), the intermediate layer (B) and the seal layer (C) contain a propylene-based resin, the intermediate layer (B) contains a plant-derived biomass polyethylene (b1), and the biomass It is a laminated film having a melt flow rate of polyethylene (b1) of 1.5 [g/10 min] or more.

[Surface layer (A)]
The surface layer (A) used for the laminated film of the present invention is a layer constituting a surface layer such as a layer on which printing of the packaging film is provided. The surface layer contains a propylene-based resin as a main resin component, and as the propylene-based resin, for example, a propylene homopolymer, a propylene-α-olefin copolymer (propylene-α-olefin random copolymer, propylene -Α-olefin block copolymer) and the like can be used.

The content of the propylene-based resin in the resin component contained in the surface layer (A) is preferably 50% by mass or more, and 70% by mass or more, because suitable fusing strength and suitability for bag making are easily obtained. It is more preferably 80% by mass or more, further preferably 85% by mass or more. Further, the resin component contained in the surface layer (A) may be a surface layer consisting essentially of a propylene resin.

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. Further, the α-olefin content is preferably 2% by mass or more, more preferably 3% by mass or more, and further preferably 4% by mass or more, since suitable impact resistance is easily obtained. ..

When the laminated film of the present invention is used as a transparent film, a propylene-α-olefin random copolymer can be preferably used as the propylene-based resin used in the surface layer (A). 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. They may be used or used together. Among them, a propylene-ethylene random copolymer can be preferably used because suitable transparency can be easily obtained.

The melt flow rate (MFR) of the propylene-ethylene random copolymer is not particularly limited as long as it can form a laminated film, but is preferably 0.5 g/10 minutes or more, and 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, 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 - density of the ethylene random copolymer, more it is preferably at most 0.880 g / cm ³ or more 0.905 g / cm ^3, is 0.890 g / cm ³ or more 0.900 g / cm ³ or less preferable.

The melting point of the propylene-ethylene random copolymer is preferably 110° C. or higher, 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 sealing during bag making, it is necessary to form a sufficient fusing ball in order to develop the fusing sealing strength. Therefore, the temperature is preferably 150° C. or lower, and more preferably 145° C. or lower.

When a propylene-ethylene random copolymer is used, the content of the propylene-ethylene random copolymer in the resin component contained in the surface layer (A) is such that suitable transparency and packaging suitability are easily obtained. , 35 mass% or more, more preferably 45 mass% or more, still more preferably 50 mass% or more. The content is preferably 75% by mass or less, more preferably 65% by mass or less, and further preferably 60% by mass or less.

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

As the propylene-ethylene-1-butene copolymer, the ethylene content and the butene content of the propylene-ethylene-1-butene copolymer are each preferably 25% by mass or less, and 15% by mass or less. Is more preferable and 10% by mass is further preferable. In addition, the ethylene content and the butene content are each preferably 0.5% by mass or more, more preferably 1.5% by mass or more, and more preferably 3% by mass, since suitable low-temperature sealing properties are easily obtained. It is more preferable that the above is satisfied.

The melt flow rate (MFR) of the propylene-ethylene-1-butene copolymer is not particularly limited as long as it can form a laminated film, but is preferably 0.5 g/10 minutes or more, and 3.0 g/ It is more preferably 10 minutes or more, and more preferably 5.0 g/10 minutes or more. Further, in order to obtain good moldability, 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-density butene copolymer is preferably not more than 0.880 g / cm ³ or more 0.905 g / cm ^3, is 0.890 g / cm ³ or more 0.900 g / cm ³ or less Is more preferable.

The melting point of the propylene-ethylene-1-butene 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 sealing during bag making, it is necessary to form a sufficient fusing ball in order to develop the fusing sealing strength, so that the temperature is preferably 145° C. or lower, and more preferably 140° C. or lower.

When using a propylene-ethylene-1-butene copolymer, the content of the propylene-ethylene-1-butene copolymer in the resin component contained in the surface layer is such that a suitable fusing seal strength can be easily obtained. Therefore, it is preferably 15% by mass or more, more preferably 25% by mass or more, and further preferably 30% by mass or more. The content is preferably 55% by mass or less, more preferably 45% by mass or less, and further preferably 40% by mass or less.

On the other hand, when the laminated film of the present invention is used as a matte film, a propylene-based block copolymer resin, particularly a propylene-α-olefin block copolymer, is used as the propylene-based resin used in the surface layer (A). It can be preferably used. Examples of the α-olefin include ethylene, 1-butene, 1-hexene, 4-methyl/1-pentene, and 1-octene. Among them, ethylene is preferable because it has a good matte feel and a good balance between cold resistance and rigidity.

The melt flow rate (MFR) of the propylene-based block copolymer resin is preferably 0.5 g/10 minutes or more because molding is easy and suitable impact resistance and a matt feeling are easily obtained. It is more preferably 1 g/10 minutes or more. Further, it is preferably 20 g/10 minutes or less, and more preferably 10 g/10 minutes or less.

The melting point of the propylene block copolymer resin is preferably 155° C. or higher, and more preferably 165° C. or lower, because suitable bag-making properties are easily obtained.

The propylene-based block copolymer resin used for the surface layer (A) may be a single copolymer or a plurality of copolymers. When a plurality of propylene block copolymer resins are used, it is preferable that the total content of the propylene block copolymer resins used is within the following range.

Examples of the propylene block copolymer resin used in the surface layer (A) and having an excellent balance between matt feeling, fusing strength and bag-making suitability include BC8, BC7 (manufactured by Nippon Polypro), E150GK, F704V (prime). Polymer company), PC480A, PC684S, PC380A, VB370A (manufactured by Sun Allomer Co.) and the like.

When a propylene-based block copolymer resin is used as the propylene-based resin, the content of the propylene-based block copolymer in the resin component contained in the surface layer (A) depends on the matt feeling, the melt-cutting strength and the bag-making suitability. The amount of the resin component used in the surface layer (A) is preferably 50% by mass or more, and more preferably 70% by mass or more. By setting it in the range, it becomes easy to obtain a uniform matte feeling excellent in design. Above all, it is preferably 80 to 100% by mass when the impact resistance is increased, and 70 to 90% by mass when the matte feeling is improved.

Further, in the surface layer (A), various olefin-based resins used for packaging films other than the propylene-based resin may be used. Examples of the olefin-based resin other than the propylene-based resin include polyethylene resins such as ultra-low density polyethylene (VLDPE), linear low-density polyethylene (LLDPE), and low-density polyethylene (LDPE), and ethylene-1-butene copolymerization. , Ethylene-vinyl acetate copolymer (EVA), ethylene-methyl methacrylate copolymer (EMMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate (EMA) copolymer, ethylene-ethyl acrylate -Ethylene-based copolymers such as maleic anhydride copolymer (E-EA-MAH), ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA); and further ethylene-acrylic acid A copolymer ionomer, an ethylene-methacrylic acid copolymer ionomer, or the like can be used. When using an olefin resin other than these propylene resins, the content of the olefin resin in the resin component contained in the surface layer (A) is preferably 20% by mass or less.

In the present invention, among these olefin resins, there is flexibility in a wide temperature range effective during bag making, and good dispersibility with the propylene resin can be obtained. It can be preferably used. The copolymer can be particularly preferably used when forming a transparent film. When the ethylene-1-butene copolymer is used, since it is easy to obtain a suitable low-temperature seal, the content of the ethylene-1-butene copolymer in the resin component contained in the surface layer is 1 to 1. It is preferably 20% by mass, and more preferably 5 to 15% by mass.

The MFR (230° C., 21.18 N) of the ethylene-1-butene copolymer is not particularly limited as long as it can form a laminated film, but is preferably 0.5 g/10 minutes or more, and 2.0 g. /10 minutes or more is more preferable, and 3.0 g/10 minutes or more is more preferable. Further, in order to obtain good moldability, 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, it is preferably at most 0.870 g / cm ³ or more 0.900 g / cm ^3, is 0.875 g / cm ³ or more 0.895 g / cm ³ or less More preferable.

As the various resins used in the surface layer (A), resins using plant-derived raw materials may be used. When it is desired to increase the plant-derived biomass material ratio in the laminated film, the content of the biomass polyolefin in the resin component contained in the surface layer (A) is preferably 10% by mass or more, and 20 to 50% by mass. Is more preferable. On the other hand, when importance is attached to the above various properties such as heat sealability, fusing sealability, and impact resistance, the content of the biomass polyolefin in the resin component contained in the surface layer (A) should be less than 10% by mass. Is preferable, and it is preferable that it is less than 5% by mass, and it is also preferable that substantially no biomass material is contained.

Various additives may be added to the surface layer (A) 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 and a pigment.

The surface roughness (Ra) based on JIS B-0601 of the surface layer (A) is preferably 0.2 to 1.0, and more preferably 0.3 to 0.7. By setting the surface roughness within the above range, the amount of additional components (additives such as slip agents and anti-blocking agents) added is reduced, or in some cases, even if they are not used together, a film having excellent surface slipperiness can be obtained. Thus, the bag-making speed can be improved, the assembling after bag-making and the packing work can be improved and made more efficient, and the workability in filling the contents with an automatic packing machine or the like can be improved.

The coefficient of friction (ASTM D-1894) of the surface layer (A) surface is preferably 0.05 to 0.7, more preferably 0.07 to 0.6, and even more preferably 0.1 to 0.5. Within the range, it is easy to improve the film feeding property during packaging, the aligning property after bag making, the packing workability, and the like, and it is easy to suitably suppress the film breakage when binding 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.

[Intermediate layer (B)]
The intermediate layer (B) of the laminated film of the present invention is a layer containing a propylene resin and further containing a plant-derived biomass polyethylene (b1) having a melt flow rate of 1.5 g/10 min or more. By using the intermediate layer, it is possible to obtain a laminated film having good heat-sealing properties and suitable fusing and sealing properties in a wide temperature range, as well as suitable impact resistance and bag breaking resistance.

The plant-derived biomass polyethylene (b1) used in the intermediate layer (B) is a polyethylene-based resin produced from plant-derived ethylene using sugar cane, corn, beet, etc. as a starting material. Examples of the biomass polyethylene (b1) 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). ), high density polyethylene (HDPE), etc., and these may be used alone or in combination of two or more. Of these, linear low-density polyethylene is particularly preferable. The linear low density Porieren, preferably density of 0.925 g / cm ³ or less, more preferably 0.920 g / cm ³ or less. By setting the density of the linear low-density polyethylene to be used within the above range, it becomes easy to combine suitable fusing strength with high impact resistance and bag breaking resistance.

The MFR of the biomass polyethylene (b1) used for the intermediate layer (B) is 1.5 g/10 min or more. By using the biomass polyethylene of the MFR, even if the content of the biomass polyethylene is increased, excellent fusing strength can be realized in a wide temperature range. The MFR is preferably 1.8 g/10 min or more, more preferably 2 g/10 min or more. Although the upper limit is not particularly limited, it is preferably 25 g/10 min or less, more preferably 20 g/10 min or less. Within the range, suitable film forming properties and moldability can be easily obtained.

The content of the plant-derived biomass polyethylene (b1) in the resin component contained in the intermediate layer (B) has a high effect of reducing environmental load, while having suitable rigidity, impact resistance, and bag-making processing as a packaging bag. From the viewpoint of easily obtaining suitability and the like, it is preferably 5% by mass or more, more preferably 8% by mass or more, and further preferably 10% by mass or more. The upper limit is not particularly limited, but in order to obtain particularly excellent impact resistance and processability, it is preferably 60% by mass or less, more preferably 50% by mass or less, and 40% by mass or less. Is particularly preferable.

The biomass polyethylene (b1) used for the intermediate layer (B) can be produced in the same manner as in the petroleum-derived production method by producing a monomer from a plant such as sugar cane as a raw material. The manufacturing method is not particularly limited and may be a known method. For example, a production method using a Ziegler-Natta catalyst or a metallocene catalyst can be mentioned.

Specifically, a titanium-containing compound itself or a titanium-containing compound supported on a carrier such as a magnesium compound is used as a main catalyst, and an organoaluminum compound is used as a cocatalyst. -A method in which olefin is added to carry out polymerization can be mentioned. This polymerization may be any process such as a slurry polymerization method, a solution polymerization method and a gas phase polymerization method.

Further, a homogeneous catalyst may be used, such as a catalyst composed of a vanadium compound and an organoaluminum compound which have been conventionally used, or a cyclopentadienyl group, a substituted cyclopentadienyl group, an indenyl group, a substituted indenyl group or the like. Transition metal compounds such as zirconium, titanium and hafnium having one or two ligands, and metallocene compounds comprising a transition metal compound in which the ligand is geometrically controlled and a cocatalyst such as aluminoxane or ionic compound. Mention may also be made of homogeneous catalyst systems such as catalysts. The metallocene catalyst may be used in any process such as a slurry polymerization method or a gas phase polymerization method in addition to homogeneous polymerization in the presence of a solvent, using an organic aluminum compound as necessary.

Examples of commercially available products of such biomass polyethylene (b1) include SLL218, SLL318, SLH218, SBC818, SPB208, SEB853 manufactured by Braschem.

In the intermediate layer (B), the above-mentioned biomass polyethylene (b1) may be used in combination with polyethylene (b2) derived from fossil fuel, which is a polyethylene resin made from fossil fuel such as petroleum. As the fossil fuel-derived polyethylene (b2), linear low-density polyethylene (LLDPE), linear medium-density polyethylene (LMDPE), linear high-density polyethylene (LHDPE), low-density polyethylene (LDPE), medium Polyethylene resin such as density polyethylene (MDPE) and high density polyethylene (HDPE), 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-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA), and other ethylene-based copolymers; further, ethylene-acrylic acid copolymer ionomers, ethylene- Examples thereof include ionomers of methacrylic acid copolymers, which may be used alone or in combination of two or more. Among these, LLDPE, LDPE, and EBR are preferable, and linear low-density polyethylene is particularly preferable. The linear low density Porieren, preferably density of 0.915 g / cm ³ or less, more preferably 0.910 g / cm ³ or less, still be at 0.906 g / cm ³ or less preferable. By setting the density of the linear low-density polyethylene to be used within the above range, it becomes easy to combine suitable fusing strength with high impact resistance and bag breaking resistance. The linear low-density polyethylene may be used alone or in combination of two or more kinds.

The MFR (190° C., 21.18 N) of linear low-density polyethylene derived from fossil fuel is preferably 10 g/10 minutes or less, and more preferably 1 to 5 g/10 minutes. By setting the MFR within the above range, the film forming property of the film is easily improved, the dispersibility is good, and a uniform film is easily obtained.

When the fossil fuel-derived polyethylene (b2) is used, the content of the fossil fuel-derived polyethylene (b2) in the resin component contained in the intermediate layer (B) depends on suitable bag making suitability and fusing seal strength. Since it is easy to obtain bag breaking resistance, it is preferably 3% by mass or more, more preferably 5% by mass or more, further preferably 8% by mass or more, and 10% by mass or more. Is particularly preferable. Further, it is preferably 30% by mass or less, more preferably 20% by mass or less, and further preferably 15% by mass or less.

As the propylene-based resin used for the intermediate layer (B), the same propylene-based resin used for the surface layer (A) can be preferably used, and a propylene homopolymer, a propylene-α-olefin copolymer (propylene -Α-olefin random copolymer, propylene-α-olefin block copolymer) and the like.

The content of the propylene-based resin in the resin component contained in the intermediate layer (B) is preferably 10% by mass or more, and 20% by mass or more, because suitable fusing strength and suitability for bag making are easily obtained. It is more preferable that the content is 30% by mass or more. Further, it is preferably 80% by mass or less, more preferably 70% by mass or less, and further preferably 60% by mass or less.

When the laminated film of the present invention is used as a transparent film, a propylene homopolymer or a propylene-α-olefin random copolymer can be preferably used as the propylene resin. Examples of the propylene-α-olefin random copolymer include a propylene-ethylene copolymer, a propylene-1-butene copolymer, a propylene-ethylene-1-butene copolymer and the like. These may be used alone or in combination.

The MFR (230° C., 21.18 N) of the propylene homopolymer is not particularly limited as long as it can form a laminated film, but is preferably 0.5 g/10 minutes or more, and 2.0 g/10 minutes or more. Is more preferable and 3.0 g/10 minutes or more is more preferable. Further, in order to obtain good moldability, 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 propylene homopolymer is preferably from 0.880 g / cm ³ or more 0.920 g / cm ^3, more preferably at most 0.885 g / cm ³ or more 0.915 g / cm ^3.

The melting point of the propylene homopolymer is preferably 145° C. or higher, and more preferably 150° C. or higher, from the viewpoint of maintaining the processability of bag making and the like.

Further, it is also preferable to use a propylene homopolymer and a propylene-α-olefin random copolymer in combination as the propylene resin. As the propylene-α-olefin random copolymer, the same one as in the above surface layer (A) can be preferably used, and particularly a propylene-ethylene copolymer can be preferably used. As the propylene-ethylene copolymer, the same one as the above-mentioned surface layer (A) when forming a transparent film can be preferably used, and the preferable range of ethylene content, MFR, density, melting point and the like is also the above-mentioned surface layer (A). The same as the propylene-ethylene copolymer that can be used in.

When a propylene homopolymer is used as the propylene-based resin, the content of the propylene homopolymer in the resin component contained in the intermediate layer (B) is 35% by mass because suitable rigidity and transparency are easily obtained. It is preferably at least 50% by mass, more preferably at least 45% by mass, further preferably at least 50% by mass. In addition, it is preferably 85% by mass or less, more preferably 80% by mass or less, and further preferably 75% by mass or less, since suitable impact strength can be easily obtained.

When a propylene-ethylene copolymer is used, the content of the propylene-ethylene copolymer in the resinous component contained in the intermediate layer (B) may be suitable bag making suitability and bag breaking resistance. Since it is easy to obtain, 5 mass% or more is preferable, and 10 mass% or more is more preferable. Further, it is preferably 30% by mass or less, and more preferably 25% by mass or less.

As the resin component contained in the intermediate layer (B), the above-mentioned various resins may be used in an appropriate content, but it is easy to suppress deterioration of rigidity and impact strength when the total thickness of the laminated film is designed to be thin. Therefore, it is preferable that the content of the propylene-based resin in the resin component contained in the intermediate layer (B) is 55% by mass or more, and the content of the ethylene-based resin is 5 to 45% by mass. Among them, the content of the propylene homopolymer in the resin component contained in the intermediate layer (B) is 50 to 80% by mass, the propylene-ethylene random copolymer is 5 to 25% by mass, and the plant-derived biomass polyethylene ( It is particularly preferable that the total amount of b1) and the polyethylene (b2) derived from fossil fuel is 5 to 45% by mass.

When the laminated film of the present invention is used as a matte film, a propylene-based block copolymer resin can be preferably used as the propylene-based resin. As the propylene-based block copolymer resin, the same propylene-based block copolymer resin as that used in the surface layer (A) for forming a matte film can be preferably used. The propylene-based block copolymer resin may be a single copolymer or a plurality of copolymers.

The content of the propylene-based block copolymer in the resin component contained in the intermediate layer (B) when forming a matte film is 95% by mass or less because suitable impact resistance and matt feeling are easily obtained. Is preferable, 85% by mass or less is more preferable, 80% by mass or less is further preferable, and 75% by mass or less is particularly preferable. Further, since it is easy to obtain suitable stability during bag making, it is preferably 15% by mass or more, more preferably 20% by mass or more, more preferably 25% by mass or more, 30% by mass. % Or more is particularly preferable.

When only three components of biomass polyethylene (b1), fossil fuel-derived polyethylene (b2) and propylene block copolymer (b3) are used as resin components contained in the intermediate layer (B), The content ratio of (biomass polyethylene (b1)/fossil fuel-derived polyethylene (b2)/propylene block copolymer (b3)) is 2/3/95 to 30/25/45 by mass ratio. Is preferable, and it is more preferable to set it as 10/5/85 to 25/20/55. With such a ratio, it is possible to obtain a laminated film having a suitable matte tone and excellent bag-breaking resistance, particularly excellent bag-breaking resistance and abrasion resistance at low temperatures.

Further, the olefin resin as described above may be used in combination with the block copolymer resin, and among them, a propylene-α-olefin random copolymer can be preferably used. As the propylene-α-olefin random copolymer, the same one as in the above surface layer (A) can be preferably used, and particularly a propylene-ethylene copolymer can be preferably used. As the propylene-ethylene copolymer, the same one as the above-mentioned surface layer (A) when forming a transparent film can be preferably used, and the preferable range of ethylene content, MFR, density, melting point and the like is also the above-mentioned surface layer (A). The same as the propylene-ethylene copolymer that can be used in.

When a propylene-α-olefin random copolymer is used in combination with the block copolymer resin, inclusion of the propylene-α-olefin random copolymer in the resin component contained in the intermediate layer (B). The amount is preferably 5% by mass or more, more preferably 15% by mass or more, and further preferably 25% by mass or more. Further, it is preferably 50% by mass or less, more preferably 45% by mass or less, and further preferably 40% by mass or less. By using a propylene-α-olefin random copolymer in the intermediate layer, it is possible to obtain more excellent fusing seal strength during bag making while maintaining bag breaking resistance.

As the resin component contained in the intermediate layer (B), the above-mentioned various resins may be used in an appropriate content, but it is easy to suppress deterioration of rigidity and impact strength when the total thickness of the laminated film is designed to be thin. Therefore, it is preferable that the content of the propylene-based resin in the resin component contained in the intermediate layer (B) is 55% by mass or more, and the content of the ethylene-based resin is 7 to 45% by mass. Among them, as the propylene-based resin, a propylene-based block copolymer (b3) and a propylene-ethylene random copolymer are used, and their total amount is 55% by mass or more. As the ethylene-based resin, plant-derived biomass is used. It is particularly preferable to use polyethylene (b1) and fossil fuel-derived polyethylene (b2) so that their total amount is 7 to 45% by mass.

Furthermore, as the resin component contained in the intermediate layer (B), only biomass polyethylene (b1), fossil fuel-derived polyethylene (b2), propylene block copolymer (b3) and propylene-ethylene random copolymer are used. The ratio of these contents (biomass polyethylene (b1)/fossil fuel-derived polyethylene (b2)/propylene block copolymer (b3)/propylene-ethylene random copolymer) is 2/3/in mass ratio. The ratio is preferably 65/30 to 25/20/15/40, more preferably 10/5/50/35 to 15/15/30/40. With such a ratio, it is possible to obtain a laminated film having a suitable matte tone and excellent bag-breaking resistance, particularly excellent bag-breaking resistance and abrasion resistance at low temperatures.

In addition, the intermediate layer (B) may also appropriately use the additives as exemplified in the surface layer.

[Seal layer (C)]
The seal layer (C) used in the present invention is a layer used for adhering the seal layers of the laminated film to each other or adhering the laminated film to another container or film. For the seal layer, a resin type that provides a suitable seal strength may be appropriately selected depending on the usage mode and the object to be sealed. For example, when the sealing layers are sealed to each other and used as a packaging bag, propylene-α-, such as propylene-ethylene random copolymer and propylene-1-butene copolymer, is obtained from the viewpoint of obtaining an appropriate sealing strength. A seal layer containing an α-olefin-propylene copolymer such as an olefin copolymer or a 1-butene-propylene copolymer can be preferably used. Among them, propylene-1-butene can be easily used because it is easy to adjust the heat-sealing temperature and strength during easy-open sealing at low temperature, has a wide heat-sealing temperature range, and is easy to obtain an appropriate heat-sealing strength as an easy-open seal. Butene resins such as polymers or 1-butene-propylene copolymers are preferred.

When a propylene-1-butene copolymer or a 1-butene-propylene copolymer is used, it is easy to obtain suitable sealing properties and blocking resistance, and therefore the 1-butene content in the copolymer is 60. The content is preferably ˜95 mol %, more preferably 65-95%, even more preferably 70-90 mol %. In addition, the propylene content is preferably 2 to 10 mol%, more preferably 3 to 9 mol%, and further preferably 4 to 8 mol% because it is easy to obtain suitable low-temperature sealability. preferable.

When a butene-based resin such as a propylene-1-butene copolymer or a 1-butene-propylene copolymer is used, the content of the butene-based resin is 50% by mass or less in the resin component contained in the seal layer. Is preferable, and it is more preferable that it is 40% by mass or less, and further preferable that it is 30% by mass or less. Further, it is preferably 10% by mass or more, and more preferably 15% by mass or more. When the content of the butene-based resin is within the range, it is easy to obtain suitable low-temperature sealing property, fusing strength and tear resistance of the bag-making product, and it is also advantageous for cost reduction.

As the resin to be used in combination with the butene-based resin, other polyolefin-based resins can be appropriately used, but since it is easy to adjust the seal strength suitably, a propylene-α-olefin copolymer or an ethylene-α-olefin copolymer is used. Polymers can be preferably used, and propylene-α-olefin copolymers can be particularly preferably used.

The content of the α-olefin in the propylene-α-olefin copolymer is not particularly limited, but is preferably 1 to 20% by mass, more preferably 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, the propylene-ethylene random copolymer as exemplified in the above intermediate layer can be preferably used. The MFR is preferably 0.5 to 20 g/10 minutes, more preferably 2 to 10 g/10 minutes, since good moldability is easily obtained.

The content of the other olefin-based resin is preferably 90% by mass or less and more preferably 85% by mass or less in the resin component contained in the seal layer, since suitable low-temperature sealing property is easily obtained. .. Further, it is preferably 50% by mass or more, and more preferably 60% by mass or more.

In particular, when forming a packaging bag using the laminated film of the present invention, in the case of providing an easy-opening portion heat-sealing the sealing layers, butene resin and propylene-α-olefin copolymer, It is preferable to use the butene resin/propylene-α-olefin copolymer in a mass ratio of 20/80 to 50/50.

Further, as the various resins used in the seal layer (C), resins using plant-derived raw materials may be used. When it is desired to increase the plant-derived biomass material ratio in the laminated film, the content of the biomass polyolefin in the resin component contained in the seal layer (C) is preferably 10% by mass or more, and 20 to 50% by mass. Is more preferable. On the other hand, when importance is attached to the above various properties such as heat sealability, fusing sealability, and impact resistance, the content of the biomass polyolefin in the resin component contained in the seal layer (C) is less than 10% by mass. Is preferable, and it is preferable that it is less than 5% by mass, and it is also preferable that substantially no biomass material is contained.

Various additives may be added to the seal layer (C) 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 and a pigment.

The friction coefficient (ASTM D1894) of the surface of the seal layer (C) is preferably 0.01 to 0.4, more preferably 0.02 to 0.35, and further preferably 0.05 to 0.30. By setting it in the range, it becomes easy to improve the film feeding property at the time of packaging and the packaging work by suppressing wrinkles and swelling after bag making. In addition, it is easy to suppress scratches caused by rubbing between the contents and the inner surface of the film when filling the contents such as bread, and to improve abrasion resistance and tear resistance, and to easily prevent film breakage. 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.

[Laminated film]
The laminated film of the present invention is a laminated film having at least the surface layer (A), the intermediate layer (B) and the seal layer (C) described above, and one surface layer of the laminated film is a surface layer and the other surface layer is It is a laminated film composed of a seal layer. The laminated film having such a structure has suitable fusing seal strength even in a wide temperature range, and is excellent in impact resistance and bag breaking resistance, and thus can be suitably used as a film for various packaging.

The thickness of the laminated film of the present invention may be appropriately adjusted depending on the use and mode of use, but the total thickness thereof is 20 because it is easy to achieve both volume reduction in packaging and bag breakage during distribution. The thickness is preferably -60 μm, more preferably 25-50 μm.

Further, the thickness and thickness ratio of each layer are not particularly limited, but for example, the thickness of the surface layer is preferably 2 to 20 μm, and more preferably 3 to 15 μm. The thickness of the intermediate layer is preferably 3 to 30 μm, more preferably 5 to 20 μm. The thickness of the seal layer is preferably 1 to 10 μm, more preferably 2 to 8 μm.

The thickness ratio of the surface layer is preferably 15% or more, and more preferably 20% or more, of the total thickness of the laminated film, since suitable fusing strength and bag making suitability are easily obtained. Further, it is preferably 35% or less, and more preferably 30% or less. The thickness ratio of the intermediate layer is preferably 30% or more, and more preferably 40% or more of the total thickness of the laminated film, since suitable rigidity, fusing strength, and bag-making suitability are easily obtained. Further, it is preferably 70% or less, and more preferably 65% or less. The thickness ratio of the seal layer is preferably 5% to 30%, and more preferably 10 to 25%, of the total thickness of the laminated film, since suitable easy-opening property, fusing strength, and suitability for bag making are easily obtained.

In the laminated film of the present invention, the content of plant-derived biomass polyethylene in the resin component contained in the entire laminated film is preferably 2% by mass or more, and more preferably 3% by mass or more, from the viewpoint of reducing the environmental load. Is more preferable and 5% by mass or more is more preferable.

The haze of the laminated film of the present invention is preferably 10% or less, more preferably 5.5% or less, and 4.5% or less because the contents to be packaged can be easily visually recognized. Is more preferable. Even when the laminated film of the present invention has such high transparency, it has suitable packaging suitability, and is unlikely to cause bag breakage such as tearing due to friction between the content and the film and rubbing. When increasing the transparency of the laminated film of the present invention, a resin component for increasing the haze such as a block copolymer is not used in each layer, or the content is preferably 10% when used. The transparency can be improved by setting the ratio to 5% or less, more preferably 5% or less.

The laminated film of the present invention may be laminated with any other resin layer other than the above surface layer, intermediate layer and seal layer, but the thickness of the other resin layer is 20% or less of the total thickness. Is preferable, and a structure including the surface layer, the intermediate layer, and the seal layer is particularly preferable. In addition, in the said structure, the intermediate|middle layer which laminated|stacked several intermediate|middle layers may be sufficient.

Specific examples of the layer structure include a three-layer structure of a surface layer/intermediate layer/seal layer in which an intermediate layer is provided between the surface layer and the seal layer, or a surface layer composed of a plurality of intermediate layers. Preferred examples include a four-layer structure of /intermediate layer 1/intermediate layer 2/seal layer. Among them, a three-layer structure composed of a surface layer/intermediate layer/seal layer can be preferably used because the characteristics of the film can be easily adjusted and the film can be easily produced.

The method for producing the laminated film of the present invention is not particularly limited, but for example, a resin or a resin mixture used for each layer is heated and melted in a separate extruder, and a method such as a coextrusion multilayer die method or a feed block method is used. A coextrusion method in which films are formed into a film by inflation, T-die/chill roll method, or the like after laminating in a molten state. This coextrusion method is preferable because the thickness ratio of each layer can be adjusted relatively freely, and a multilayer film having excellent hygiene and cost performance can be obtained. Since the laminated film obtained by the manufacturing 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 that the surface layer is subjected to a surface treatment in order to improve the adhesion with the printing ink. Examples of such surface treatment include corona 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 sandblasting. Corona treatment is preferred.

Examples of the packaging material made of the laminated film of the present invention include packaging bags, containers, lid materials for containers used for applications such as foods, chemicals, industrial parts, sundries, magazines and the like. In particular, since it has a matt feeling that is unprecedented and excellent, a packaging material similar to Japanese paper can be provided, and it can be suitably used for foods and the like used to bring out a high-grade feeling.

The packaging bag, the sealing layer of the laminated film of the present invention as a heat-sealing layer, heat-sealing by stacking the sealing layers, or by heat-sealing the surface layer and the sealing layer, the sealing layer as the inside It is preferably a formed packaging bag. For example, two pieces of the laminated film are cut out into a desired size of a packaging bag, they are stacked and heat-sealed on three sides to form a bag, and then the content is filled from one side which is not heat-sealed. It can be used as a packaging bag by heat sealing and sealing. Further, it is also possible to form a packaging bag by sealing the roll-shaped film into a cylindrical shape at the ends and then sealing the top and bottom with an automatic packaging machine.

In the case of a packaging bag for bread, the packaging surface can be formed by folding the printed surface and sealing the packaging bag. Specifically, the laminated film of the present invention is processed into a bottom gusset bag with a bag-making machine, for example, HK-40 manufactured by Totani Giken Co., Ltd. so that the sealing layer of the laminated film is inside the bag. Since the laminated film of the present invention can realize suitable fusing strength and suitability for bag making, it can be particularly suitably used for bottom gusset bag applications. Adjust the fusing seal temperature and bag making speed so that the fusing seal strength of the side part of the bottom gusset bag and the bottom gusset part (folding part of the bottom) is 7.5 N to 30 N/15 mm, preferably 10 to 30 N/15 mm. Is preferred.

The obtained bottom gusset bag is supplied to a bread automatic filling machine, and after filling bread, it is easy to open and has a heat seal strength of 0.1 to 5 N/15 mm, preferably 0.2 to 4 N/15 mm. Heat-seal to form an easily openable bread packaging bag, and if necessary, form an easily openable seal part on the upper part of the bag, preferably the upper part of the bread, or the upper part of the bag with a plastic plate, tape, string, etc. You may seal by binding using the binding tool of.

In addition, 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., is used so that the sealing layer is inside the bag. Supplied in roll form. 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 packaging machine, the heat-sealing surfaces of the films are overlapped and heat-sealed to form a bag, and the bread is contained therein. At this time, it is preferable to adjust the heat-sealing temperature and the packaging speed so that the sealing strength between the bottom portion and the back-applied portion of the pillow packaging bag by the packaging machine is 7.5 N to 30 N/15 mm, preferably 8 to 20 N/15 mm. .. Next, heat-sealing may be performed under the conditions of easy opening and heat sealing strength of 0.1 to 5 N/15 mm, preferably 0.2 to 4 N/15 mm to form an easily openable sealing portion, and its vicinity. May be bound using a binding tool such as a plastic plate, tape, or string.

It is also possible to form a packaging bag/container/lid of a container by stacking another heat-sealable film on the seal layer and heat-sealing the film. At this time, as another film to be used, a film of LDPE, EVA, polypropylene or the like having a relatively low mechanical strength can be used. Also, a laminated film obtained by laminating a film such as LDPE, EVA, or polypropylene with a stretched film having relatively good tearability, such as a biaxially oriented polyethylene terephthalate film (OPET) or a biaxially oriented polypropylene film (OPP). Can be used.

As described above, since the laminated film of the present invention can realize suitable impact resistance and bag breakage resistance, it can be suitably applied to various packaging applications. In particular, since excellent impact resistance can be achieved even at low temperatures, it is suitable 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. In addition, pinholes and tears are less likely to occur even when contact with the binding tool or the transport container occurs during transfer. Also, pinholes and tears due to friction between the food as the contents and the inner surface of the film (sealing surface), friction with the mixed plastic tray, and piercing are less likely 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 can be particularly suitably applied to bread packaging applications.

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.

(Example 1)
The following resins were used as the resin components forming each of the surface layer, the intermediate layer and the seal layer, and a resin mixture forming each layer was prepared. These mixtures were respectively fed to three extruders and coextruded so that the average thickness of each layer of the laminated film formed by the surface layer/intermediate layer/seal layer was 7/18/5 μm, A 30 μm laminated film was formed. Next, the surface layer of the obtained laminated film was subjected to corona discharge treatment so that the surface energy was 33 mN/m to obtain a laminated film.

Surface layer: propylene-ethylene copolymer (ethylene content: 2%, density: 0.90 g/cm ³ , melt index (hereinafter referred to as MI): 6 g/10 minutes, melting point 140° C.) (hereinafter COPP (1 55 parts by mass and propylene-ethylene-1-butene terpolymer (density: 0.90 g/cm ³ , MFR: 5.4 g/10 minutes (190° C., 21.18 N)). A mixture of 35 parts by mass and 10 parts by mass of a crystalline ethylene-1-butene copolymer (density: 0.88 g/cm ³ , MI: 4 g/10 min). Intermediate layer: propylene homopolymer (density: 0 .90 g/cm ³ , MFR: 7.5 g/10 minutes) (hereinafter referred to as HOPP (1)) 65 parts by mass, and a propylene-ethylene copolymer (ethylene content: 5.2%, density: 0.1). 90 g/cm ³ , MFR: 5.4 g/10 minutes) (hereinafter referred to as COPP(2)) 10 parts by mass and linear low-density polyethylene (density: 0.905 g/cm ³ , MFRI: 4.0 g). /10 minutes) (hereinafter, referred to as LLDPE (1)) 15 parts by mass, and a linear low-density polyethylene-based resin derived from sugarcane, which is biopolyethylene, SLL318 manufactured by Braskem (density: 0.918 g/cm ³ , MFR). = 2.7 g/10 min) (hereinafter referred to as bio-PE (1)) 10 parts by mass of resin mixture Seal layer: COPP (2) 70 parts by mass, 1-butene-propylene copolymer (density: 0. 90 g/cm ³ , MFR (measurement temperature 230° C.): 4 g/10 minutes) 30 parts by mass

(Example 2)
A laminated film was obtained in the same manner as in Example 1 except that the resin component of the resin mixture used for the intermediate layer was changed to the following.
Intermediate layer: 65 parts by mass of HOPP (1), 10 parts by mass of COPP (2), 15 parts by mass of LLDPE (1), SLH218 (straight density low density polyethylene-based resin derived from sugar cane, which is biopolyethylene) (density: 0. 916 g/cm ³ , MFR=2.3 g/10 min) (hereinafter referred to as Bio-PE(2)) 10 parts by mass

(Example 3)
A laminated film was obtained in the same manner as in Example 1 except that the resin component of the resin mixture used for the intermediate layer was changed to the following.
Intermediate layer: 60 parts by mass of HOPP(1), 15 parts by mass of COPP(2), 10 parts by mass of LLDPE(1), 15 parts by mass of bio-PE(1)

(Example 4)
A laminated film was obtained in the same manner as in Example 1 except that the resin component of the resin mixture used for the intermediate layer was changed to the following.
Intermediate layer: 55 parts by mass of HOPP(1), 20 parts by mass of COPP(2), 10 parts by mass of LLDPE(1), 15 parts by mass of bio-PE(2).

(Example 5)
The resin components of the resin mixture used for the surface layer and the intermediate layer are as follows, and they are co-extruded so that the average thickness of each layer of the laminated film formed by the surface layer/intermediate layer/seal layer is 7/18/5 μm. A laminated film was formed in the same manner as in Example 1 except for the above.
Surface layer: Propylene-ethylene block copolymer (density: 0.90 g/cm ³ , MI: 8 g/10 minutes, melting point 160° C.) (hereinafter referred to as propylene-based block copolymer (1)) 100 parts by mass Intermediate Layer: 35 parts by mass of COPP (2), propylene-ethylene block copolymer (density: 0.90 g/cm ³ , MI: 6 g/10 minutes, melting point 160° C.) (hereinafter, propylene block copolymer (2) 40 parts by mass, LLDPE (1) 10 parts by mass, Bio PE (1) 15 parts by mass

(Example 6)
A laminated film was obtained in the same manner as in Example 5 except that the resin component of the resin mixture used for the intermediate layer was changed to the following.
Intermediate layer: 35 parts by mass of COPP (2), 40 parts by mass of propylene-based block copolymer (2), 10 parts by mass of LLDPE (1), 15 parts by mass of bio-PE (2)

(Example 7)
A laminated film was obtained in the same manner as in Example 5 except that the resin component of the resin mixture used for the intermediate layer was changed to the following.
Intermediate layer: 35 parts by mass of COPP (2), 35 parts by mass of propylene-based block copolymer (2), 10 parts by mass of LLDPE (1), 20 parts by mass of bio-PE (1)

(Example 8)
A laminated film was obtained in the same manner as in Example 5 except that the resin component of the resin mixture used for the intermediate layer was changed to the following.
Intermediate layer: 35 parts by mass of COPP (2), 40 parts by mass of propylene block copolymer (2), 5 parts by mass of LLDPE (1), 20 parts by mass of bio-PE (2)

(Comparative Example 1)
A laminated film was obtained in the same manner as in Example 1 except that the resin component of the resin mixture used for the intermediate layer was changed to the following.
Middle layer: 65 parts by mass of HOPP (1), 10 parts by mass of COPP (2), 15 parts by mass of LLDPE (1), a linear low-density polyethylene-based resin derived from sugar cane, which is a biopolyethylene, SLM118 of Braskem (density: 0. 918 g/cm ³ , MFR=1.0 g/10 min) (hereinafter, referred to as Bio PE (3)) 10 parts by mass

(Comparative example 2)
A laminated film was obtained in the same manner as in Example 1 except that the resin component of the resin mixture used for the intermediate layer was changed to the following.
Intermediate layer: 60 parts by mass of HOPP(1), 15 parts by mass of COPP(2), 10 parts by mass of LLDPE(1), 15 parts by mass of bio-PE(3)

(Comparative example 3)
A laminated film was obtained in the same manner as in Example 5 except that the resin component of the resin mixture used for the intermediate layer was changed to the following.
Intermediate layer: 35 parts by mass of COPP (2), 40 parts by mass of propylene block copolymer (2), 10 parts by mass of LLDPE (1), 15 parts by mass of bio-PE (3)

(Comparative Example 4)
A laminated film was obtained in the same manner as in Example 5 except that the resin component of the resin mixture used for the intermediate layer was changed to the following.
Intermediate layer: 35 parts by mass of COPP (2), 35 parts by mass of propylene block copolymer (2), 10 parts by mass of LLDPE (1), 20 parts by mass of bio-PE (3)

(Reference example 1)
A laminated film was obtained in the same manner as in Example 1 except that the resin component of the resin mixture used for the intermediate layer was changed to the following.
Intermediate layer: 75 parts by mass of HOPP(1), 15 parts by mass of COPP(2), 10 parts by mass of LLDPE(1)

The following tests and evaluations were performed using the laminated films obtained in the above Examples and Comparative Examples. The results obtained are shown in the table below.

[Measurement of stiffness]
The 1% tangent modulus (unit: MPa) of the films obtained in Examples and Comparative Examples at 23° C. was measured according to ASTM D-882 using a Tensilon tensile tester [manufactured by A&D Co., Ltd.]. It was measured. The measurement was performed in the extrusion direction (hereinafter referred to as "MD") and the film width direction (hereinafter referred to as "CD") during film production.
⊚: rigidity is 600 MPa or more ◯: rigidity is 550 MPa or more and less than 600 MPa Δ: rigidity is 450 or more and less than 550 MPa x: rigidity is less than 450 MPa

[Evaluation of suitability for bag making]
The film obtained in Examples and Comparative Examples was folded in half with the sealing layer on the inside, and then a gusset was placed at the bottom, and a fusing seal was made at a sealing temperature (bag making temperature) of 300° C. (bag making). Machine: HK-40 manufactured by Totani Giken Co., Ltd., bag making speed: 120 sheets/minute to make a bottom gusset bag (length: 345 mm (side part: 245 mm, gusset part: 60 mm), width 235 mm), The bag making suitability was evaluated. In addition, 300 sheets as one set were aligned and bundled to evaluate the alignment.
◯: The film follows the bag making speed of 120 shots, and there is no problem with the aligning property. Δ: The film follows the bag making speed of 120 shots, but there is a problem with the aligning property. Some bags cannot keep up with the bag speed, and the alignment is poor.

[Fusing strength]
Using the films obtained in Examples and Comparative Examples, a bottom gusset bag was produced in the same manner as the bag making suitability evaluation. Test pieces having a length of 70 mm and a width of 15 mm were respectively formed from the center of the gusset portion on both sides of the obtained bottom gusset bag and the center of the side portion other than the gusset so that the fusing seal portion would be the center portion in the length direction. Ten sheets were cut out, and the maximum load when pulled by a Tensilon tensile tester (manufactured by A&D Co., Ltd.) at 23° C. and a pulling speed of 300 mm/min was measured as the fusing strength. The same measurement was carried out by changing the sealing temperature (bag making temperature) of the fusing seal in the range of 260°C to 360°C at every 20°C.
⊚: The fusing strength of both the gusset portion and the side portion is 16 N/15 mm or more ◯: The fusing strength of both the gusset portion and the side portion is 15 N/15 mm or more and less than 16 N/15 mm ○ △: The fusing strength of the gusset portion and the side portion All are 14.5 N/15 mm or more and less than 15 N/15 mm Δ: The fusing strength of the gusset portion and the side portion is 13 N/15 mm or more and less than 14.5 N/15 mm ×: The fusing strength of at least one of the gusset portion and the side portion is 13 N / Less than 15 mm

[Heat seal strength]
Using the films obtained in Examples and Comparative Examples, a bottom gusset bag was produced in the same manner as the bag making suitability evaluation. A heat sealer (manufactured by Tester Sangyo Co., Ltd.: pressure 0.2 MPa, time 1 second, sealing temperature: upper seal bar 95° C., 50 mm below the upper end of the opening of the obtained bottom gusset bag and parallel to the opening. Heat sealing was performed with a lower seal bar at 50° C. and a seal bar shape: a plane of 300 m×10 mm). Test pieces each having a length of 70 mm and a width of 15 mm were cut out from each of the obtained five heat-seal parts of the bottom gusset bag, 10 pieces each at a temperature of 23° C. The maximum load when peeled off with a Tensilon tensile tester (manufactured by A&D Co., Ltd.) at a pulling speed of 300 mm/min was measured as the heat seal strength.
◯: Heat seal strength is less than 5 N/15 mm, no film tear when peeled off ×: Heat seal strength is 5 N/15 mm or more, or film tear when peeled off

[Measurement of impact strength]
The films obtained in Examples and Comparative Examples were held in a thermostatic chamber adjusted to 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.
⊚: Impact strength of 0.20 or more ◯: Impact strength of 0.15 (J) or more and less than 0.20 Δ: Impact strength of 0.1 (J) or more and less than 0.15 ×: Impact strength of 0.1( Less than J)

As is clear from the above table, the laminated films of the present invention of Examples 1 to 8 had suitable seal strength and impact resistance, and had good fusing seal strength in a wide temperature range. .. On the other hand, in the laminated films of Comparative Examples 1 to 4, it was difficult to obtain good fusing seal strength in a wide temperature range.

Claims (14)

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) contain a propylene resin,
The intermediate layer (B) contains a plant-derived biomass polyethylene (b1),
A laminated film, wherein the melt flow rate of the biomass polyethylene (b1) is 1.5 g/10 min or more. The laminated film according to claim 1, wherein the biomass polyethylene (b1) is linear low-density polyethylene. Content of the biomass polyethylene (b1) in the resin component contained in the said intermediate|middle layer (B) is 15 mass% or more, The laminated|multilayer film of Claim 1 or 2. The intermediate layer (B) contains, as a propylene-based resin, a propylene-ethylene copolymer resin in an amount of 5% by mass or more based on a resin component contained in the intermediate layer (B). Laminated film. The laminated film according to any one of claims 1 to 4, wherein the surface layer (A) contains a propylene-ethylene random copolymer resin in an amount of 50% by mass or more based on a resin component contained in the surface layer (A). The laminated film according to claim 5, wherein the intermediate layer (B) contains 30% by mass or more of a propylene homopolymer in a resin component contained in the intermediate layer (B). The laminated film according to any one of claims 1 to 4, wherein the surface layer (A) contains a propylene-based block copolymer resin in an amount of 50% by mass or more based on a resin component contained in the surface layer (A). The laminated film according to claim 7, wherein the intermediate layer (B) contains a propylene-based block copolymer resin in an amount of 15% by mass or more based on the resin components contained in the intermediate layer (B). The laminated film according to claim 1, wherein the seal layer (C) contains a propylene-ethylene copolymer resin and a butene resin. The laminated film according to claim 1, wherein the intermediate layer (B) contains 3% by mass or more of the fossil fuel-derived polyethylene (b2) in the resin component contained in the intermediate layer (B). The laminated film according to claim 10, wherein the fossil fuel-derived polyethylene (b2) has a melt flow rate of 3 to 10 g/10 min. A food packaging bag using the laminated film according to claim 1. The food packaging bag according to claim 12, which has a gusset portion. The food packaging bag according to claim 12 or 13, which is used for bread packaging.