JP2006205711A - Laminated biaxial stretched polyamide-based film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated biaxial stretched polyamide-based film which is excellent in impact resistance and flexion-fatigue resistance, especially in flexion-fatigue resistance under low-temperature environment, which is effective to prevent packs from breaking during transportation and storage of goods when it is used as a packaging material such as food packaging or the like, furthermore effectiveness to prevent a large-sized heavy weight bags such as a professional-use way or the like from breaking by falling, and which is suitable for various packaging applications. <P>SOLUTION: The laminated biaxial stretched polyamide based film comprises laminating the layer B consisting of a mixed polyamide polymer comprising 99.5-0.5 wt.% of an aliphatic polyamide polymer and 0.5-99.5 wt.% of a semi-aromatic polyamide polymer to at least one surface of a layer A consisting of a mixed polymer comprising 97-80 wt.% of an aliphatic polyamide polymer and 3-20 wt.% of a thermoplastic elastomer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is excellent in impact resistance and bending fatigue resistance, in particular, bending fatigue resistance in a low-temperature environment, and when used as a packaging material for food packaging etc., prevents bag breakage during transportation and storage of goods, etc. In addition, the present invention relates to a laminated biaxially stretched polyamide film suitable for various packaging applications, which is effective in preventing the falling bag breakage of large heavy bags for business use.

  Conventionally, unstretched films and stretched films made of aliphatic polyamides typified by nylon 6 and nylon 66 are excellent in impact resistance and bending fatigue resistance, and various packaging material films have been used.

  In addition, for liquid-filled packaging such as soups and seasonings, various elastomers (rubber components) are mixed with aliphatic polyamide in a single layer configuration to further improve flex fatigue resistance and impact resistance. Widely used stretched polyamide films for pinholes are used.

  In the above conventional pinhole-resistant film, a film obtained by mixing an aliphatic polyamide with a polyolefin-based elastomer has good bending fatigue resistance and impact resistance at room temperature, but when subjected to a low-temperature environment, bending fatigue resistance, There is a problem that impact resistance is deteriorated and pinholes are likely to occur due to bending fatigue during transportation of goods. If a pinhole occurs in the packaging material of a product, it may cause contamination due to leakage of the content, decay of the content, generation of mold, etc., leading to a decrease in product value.

On the other hand, a film in which a polyamide-based elastomer is mixed with an aliphatic polyamide is known (for example, see Patent Document 1).
The film has good bending fatigue resistance and impact resistance under a low temperature environment, and pinholes are hardly generated due to bending fatigue even under a low temperature environment.
JP-A-11-254615

  However, since the dispersion diameter of the polyamide-based elastomer in the aliphatic polyamide is large, the impact when the bag-making product is dropped propagates to the polyamide-based elastomer particles dispersed with a large particle size in the polyamide-based film one after another. There is a tendency to tear easily in the thickness direction. For this reason, falling bag breakage is likely to occur in a large weight bag using a pinhole polyamide film mixed with a polyamide-based elastomer.

  Furthermore, the thickness of the polyethylene resin layer for heat sealing was increased for the purpose of imparting the waist of the bag-made product for improving the handleability at the time of bag making processing and improving the workability at the time of filling the contents into the bag. Alternatively, in a bag-made product having a polyamide-based film / polyethylene resin configuration in which a harder polyethylene resin is selected, pinholes are likely to be vacant because the bag-made product becomes stiff. Therefore, the polyamide-type film used for these requires further pinhole resistance.

  There is also an increasing demand for bag-in-box, which is a packaging form for storing, storing, and transporting large plastic bags in commercial heavy-duty bags or cardboard boxes having a volume of 1 liter or more. In addition to the above-mentioned bending fatigue resistance and impact resistance, the polyamide-based film used in these is packaged with a large volume of liquid material, so it has strong drop bag resistance and strong cohesive failure strength in the film thickness direction. Is needed.

  Thus, as the degree of correspondence to the expanded required properties in the current pinhole polyamide film, the polyolefin elastomer mixed polyamide film is inferior in bending fatigue resistance and impact strength in a low temperature environment, Polyamide-based elastomer-mixed polyamide-based films tend to have good bending fatigue resistance and impact strength even in low-temperature environments, but there is a problem that satisfactory levels cannot be achieved with drop bag resistance and strong cohesive fracture strength in the film thickness direction. there were.

  In view of the problems of the above-mentioned current pinhole-resistant polyamide-based film, the present invention is excellent in impact resistance and bending fatigue resistance, in particular, bending fatigue resistance in a low temperature environment, and as a packaging material for food packaging, etc. Stacked biaxial suitable for various packaging applications that are effective in preventing bag breakage during transportation and storage of products, and also effective in preventing falling bags of large heavy bags for business use. An object is to provide a stretched polyamide film.

  In order to achieve the above object, the laminated biaxially stretched polyamide film of the present invention is at least one of layer A comprising a mixed polymer of 97 to 80% by weight of an aliphatic polyamide polymer and 3 to 20% by weight of a thermoplastic elastomer. Layer B comprising a mixed polyamide polymer of 99.5 to 0.5% by weight of an aliphatic polyamide polymer and 0.5 to 99.5% by weight of a semi-aromatic polyamide polymer, The impact strength is 0.95 J or more, the number of pinholes is 5 or less, and the laminate strength is 5.5 N / 15 mm or less.

  In this case, the thickness of the A layer is preferably 20 to 93% of the total thickness of the A layer and the B layer, and the thickness of the B layer is preferably at least 1 μm or more.

  Moreover, it is preferable that the thermoplastic elastomer which comprises A layer is 1 type, or 2 or more types of elastomers chosen from the polyamide-type elastomer, the polyolefin-type elastomer, or the ionomer polymer.

  The B layer is preferably composed of a mixed polyamide polymer of 99.5 to 50.0% by weight of an aliphatic polyamide polymer and 0.5 to 50.0% by weight of a semi-aromatic polyamide polymer.

  The B layer is preferably composed of a mixed polyamide polymer of 99.5 to 50.0% by weight of a semi-aromatic polyamide polymer and 0.5 to 50.0% by weight of an aliphatic polyamide polymer.

  Moreover, it is preferable that the polyamide polymer which comprises A layer and / or B layer contains 0.01 to 0.40 weight% of aliphatic amide and / or aliphatic bisamide.

  Moreover, it is preferable that the mixed polymer which comprises A layer contains antioxidant 0.1 to 0.1weight%.

  Moreover, it is preferable that the antioxidant which the mixed polymer which comprises A layer contains is a phenolic antioxidant.

  Furthermore, the phenolic antioxidant contained in the mixed polymer constituting the layer A is one or more phenolic compounds selected from a completely hindered phenolic compound or a partially hindered phenolic compound. It is preferable.

  In the laminated biaxially stretched polyamide film of the present invention, the A layer having a structure in which a thermoplastic elastomer as a pinhole resistant material is dispersed in an aliphatic polyamide polymer is mainly composed of impact resistance and flex fatigue resistance. This contributes to the development of the fatigue resistance, particularly in a low temperature environment. In addition, layer B made of a mixed polyamide polymer of an aliphatic polyamide polymer and a semi-aromatic polyamide polymer has an excellent cohesive strength in the thickness direction of the film, and breaks the impact that is applied to the bag-making product when dropped. It contributes to the expression of bag prevention, and achieves both high bending fatigue resistance and bag breakage prevention by the synergistic effect of each characteristic. And, it has excellent impact resistance and bending fatigue resistance, in particular, it has good bending fatigue resistance under low temperature environment, and has excellent cohesive fracture strength in the film thickness direction, and has a resistance to falling bag Good strength.

Due to the above characteristics, when used as packaging materials for food packaging, liquid packaging, etc., it is effective in preventing bag breakage due to bending fatigue due to impact and vibration during transportation, especially during low temperature transportation and storage In addition, it is effective in preventing bag breakage even when the bag-made product is dropped during transportation or storage.
Furthermore, it is also effective for preventing falling bags and preventing pinholes when used as a large heavy duty bag for business purposes. Furthermore, blocking and slipping failure at the time of bag making and filling of the product into the bag-made product can be prevented, stable workability can be given, and it can be effectively used as various packaging materials.
In particular, for use as a large-sized heavy bag for business use, it is desirable that the impact strength is 0.95 J or more, the number of pinholes is 5 or less, and the laminate strength is 5.5 N / 15 mm or less.

  The laminated biaxially stretched polyamide film of the present invention is excellent in impact resistance and bending fatigue resistance, in particular, bending fatigue resistance in a low temperature environment, and when used as a packaging material for food packaging, etc. It can be effectively used as various packaging materials that are effective in preventing bag breakage during storage and the like, and also effective in preventing fallen bag breakage of large heavy bags for business use.

Hereinafter, embodiments of the laminated biaxially stretched polyamide film in the present invention will be described in detail.
In the present invention, the layer A is composed of a mixed polymer of 97 to 80% by weight of an aliphatic polyamide polymer and 3 to 20% by weight of a thermoplastic elastomer. Such layer A has a structure in which a thermoplastic elastomer as a pinhole-resistant material is dispersed in an aliphatic polyamide polymer excellent in impact resistance and bending fatigue resistance. In particular, it contributes to improvement of bending fatigue resistance in a low temperature environment. Here, if the mixing amount of the thermoplastic elastomer constituting the A layer is less than 3%, the highly required bending fatigue resistance exceeding the current pinhole resistant polyamide stretched film cannot be obtained. On the other hand, if the mixing amount exceeds 20%, the transparency is poor and the bending fatigue resistance is saturated. Next, the B layer composed of a mixed polyamide polymer with an aliphatic polyamide polymer and a semi-aromatic polyamide polymer reduces adhesion by mixing the semi-aromatic polyamide polymer, and the intermolecular force between the polyamide polymers. By reducing the influence of moisture leading to a decrease, the layer B has a strong cohesive strength in the film thickness direction, and the B layer has a structure laminated on at least one side of the A layer.

  When the laminated biaxially stretched polyamide film of the present invention is processed into a bag product, the heat seal material is laminated on the outer surface of the B layer, and when the bag product falls, the impact is sealed from the contents of the bag. Propagate to the department. In the configuration of the present invention, the B layer having a high cohesive strength receives the impact, and the impact is not propagated to the external A layer, thereby exhibiting a high bag breaking prevention property.

In this case, when the thickness of the layer B is large and occupies the total thickness of the film, high anti-bag breaking property is secured, but the bending fatigue resistance is greatly lowered. On the other hand, when the thickness of the layer A almost occupies the total thickness of the film, the anti-bag breaking property cannot be ensured although the bending fatigue resistance is excellent.
Therefore, in the present invention, the thickness of the A layer is 20 to 93% of the total thickness of the A layer and the B layer,
60 to 90% is particularly preferable. Moreover, by making the thickness of the B layer at least 1 μm or more, it is possible to effectively express both the bending fatigue resistance and the bag breaking prevention property.

  The aliphatic polyamide polymer constituting the layer A of the laminated biaxially stretched polyamide film of the present invention can be used as a film molding material and is not particularly limited as long as it is suitable for forming the above structure. Is included. For example, aliphatic polyamide homopolymers such as nylon 6, nylon 6,6, nylon 11, nylon 12, nylon 6,10, etc., or monomers copolymerizable therewith are 10 wt% or less, preferably 1-10 wt% Copolymers, for example, aliphatic polyamides such as nylon 6/6/6 copolymer, nylon 6/12, nylon 6/6/10 copolymer, nylon 6/6/6/10 copolymer, etc. A small amount in which aliphatic polyamide represented by copolymer or ε-caprolactam is the main component and this is copolymerized with nylon salt of hexamethylenedimine and isophthalic acid or nylon salt of metaxylylenediamine and adipic acid. A polyamide copolymer containing any of the above aromatics can be used.

  The thermoplastic elastomer mixed in the A layer is a material having thermoplasticity as a substance having rubber-like elasticity, and is not particularly limited as long as it is suitable for forming the above structure. More specifically, examples include polyamide elastomers, polyolefin elastomers, polystyrene elastomers, polyurethane elastomers, polyester elastomers, polyvinyl chloride elastomers, ionomer polymers, and the like, and mixtures of these elastomers. A thermoplastic elastomer can be used individually or in combination of 2 or more types.

  In the present invention, the thermoplastic elastomer may be modified within a range that does not impair the gist of the present invention. For example, the modified body of the thermoplastic elastomer illustrated above may be used. Examples of the modification in the thermoplastic elastomer include modification by copolymerization or graft modification, modification by imparting a polar group, and the like. The application of the polar group may be performed by graft modification. Examples of such a polar group include an epoxy group, a carboxyl group, an acid anhydride group, a hydroxyl group, an amino group, and an oxo group. A polar group can be provided by one kind or a combination of plural kinds. Accordingly, the modified products to which polar groups have been added include, for example, epoxy-modified products, carboxy-modified products, acid anhydride-modified products, hydroxy-modified products, and amino-modified products of thermoplastic elastomers.

  As the thermoplastic elastomer, a polyamide-based elastomer, a polyolefin-based elastomer, and an ionomer polymer can be suitably used.

  Examples of the polyamide-based elastomer include polyamide-based block copolymers composed of a hard segment composed of a polyamide component and a soft segment composed of a polyoxyalkylene glycol component. The polyamide component of the hard segment is selected from the group consisting of (1) lactam, (2) ω-amino aliphatic carboxylic acid, (3) aliphatic diamine and aliphatic dicarboxylic acid, or (4) aliphatic diamine and aromatic dicarboxylic acid. Specific examples include lactams such as ε-caprolactam, aliphatic diamines such as aminoheptanoic acid, aliphatic dicarboxylic acids such as adipic acid, and aromatic dicarboxylic acids such as terephthalic acid. Examples of the polyoxyalkylene glycol constituting the soft segment of the polyamide-based block copolymer include polyoxytetramethylene glycol, polyoxyethylene glycol, polyoxy-1,2-propylene glycol and the like.

  The melting point of the polyamide-based block copolymer is determined by the type and ratio of the hard segment composed of the polyamide component and the soft segment composed of the polyoxyalkylene glycol component, but usually in the range of 120 ° C to 180 ° C. Is used.

  By using a polyamide block copolymer as a component of a laminated biaxially stretched polyamide film, it is effective in improving the bending fatigue resistance of the laminated biaxially stretched polyamide film, particularly in a low temperature environment. is there.

  The polyolefin elastomer is not particularly limited, and examples thereof include a block copolymer having a polyolefin as a hard segment and various rubber components as a soft segment. Examples of the polyolefin constituting the hard segment include ethylene, propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-octene, 1-decene and 1-dodecene. , 1-tetradecene, 1-hexadecene, 1-octadecene, and the like, homopolymers or copolymers such as α-olefins having about 2 to 20 carbon atoms. Polyolefin can be used alone or in combination of two or more. Preferred olefins include ethylene and propylene. Examples of the rubber component constituting the soft segment include ethylene-propylene rubber (EPR), ethylene-propylene-diene rubber (EPDM), polybutadiene, polyisoprene, natural rubber (NR), nitrile rubber (NBR; acrylonitrile). Butadiene rubber), styrene-butadiene rubber (SBR), chloroprene rubber (CR), butyl rubber (IIR), hydrogenated NBR (H-NBR), acrylonitrile-isoprene rubber (NIR), acrylonitrile-isoprene-butadiene rubber (NBIR), etc. Is mentioned. These rubber components include, for example, acid-modified rubbers such as carboxylated rubber containing unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, and maleic anhydride as comonomers, other modified rubbers, and hydrogenated products. Etc. are also included. These rubber components can be used alone or in combination of two or more.

In addition, the ionomer polymer is not particularly limited, and a block copolymer obtained by making various rubber components obtained by acid modification with an unsaturated carboxylic acid using a polyolefin as a hard segment and further neutralizing with a metal ion. Is mentioned. As a preferable ionomer polymer, a copolymer resin composed of ethylene and methacrylic acid or ethylene, methacrylic acid and acrylic ester is neutralized with a metal ion containing Na ⁺ , K ⁺ and Zn ^2+. And an ionomer polymer.

  The mixed polymer constituting the A layer is a mixture of the aliphatic polyamide polymer and the thermoplastic elastomer. This mixed polymer may be a mixture of the above-mentioned aliphatic polyamide polymer and thermoplastic elastomer of the virgin raw material, and a standard generated when the laminated biaxially stretched polyamide film of the present invention is produced. It may be prepared by adding waste material generated as an outer film or cut end material (ear trim), and its recycled resin and virgin raw material.

  The mixed polymer constituting the layer A of the laminated biaxially stretched polyamide film of the present invention may contain 0.01 to 0.1% by weight of a phenolic antioxidant. When using recovered and recycled raw materials such as scrap materials and recycled resin as the mixed polymer of layer A, it is possible to reduce the poor film forming operability due to thermal deterioration of the recovered recycled raw materials and realize stable film forming operability. Preferably contains 0.01 to 0.1% by weight of an antioxidant.

  If the ratio of the antioxidant mixed in the mixed polymer of layer A exceeds the upper limit of the above range, whitening due to precipitation on the surface of the laminated biaxially oriented polyamide film, adhesion during lamination with polyethylene or polypropylene sealant When the lower limit of the above range is exceeded, the film-forming operability due to thermal degradation of the recovered recycled material when using the recovered recycled material such as scrap material and recycled resin as the mixed polymer of the A layer Defects may occur.

  In the present invention, the antioxidant that can be contained in the mixed polymer of the layer A is preferably a phenolic antioxidant. In the present invention, the phenol-based antioxidant contained in the mixed polymer of the layer A is preferably a completely hindered phenol compound or a partially hindered phenol compound. Examples include tetrakis- [methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane, stearyl-β- (3,5-di-t-butyl-4 -Hydroxyphenyl) propionate, 3,9-bis [1,1-dimethyl-2- [β- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy] ethyl] 2,4,8, And 10-tetraoxaspiro [5,5] undecane.

  By including the phenolic antioxidant in the mixed polymer of the layer A of the laminated biaxially stretched polyamide film, the film forming operability of the laminated biaxially stretched polyamide film is improved. In particular, in a recovered / recycled raw material mixing system using scrap film, recycled resin, etc., thermal degradation is likely to occur due to recovery and regeneration of the thermoplastic elastomer, and film formation operation failure due to this occurs. There is a tendency to increase production costs due to an increase in production costs and an increase in raw material costs for maintaining operability due to a decrease in the amount of recovered recycled materials used. On the other hand, by adding the above-mentioned phenolic antioxidant to the mixed polymer of the A layer of the polyamide biaxially stretched film containing the recovered and recycled raw materials, the heat of various polymers including thermoplastic elastomers can be obtained. Deterioration is suppressed and stable film forming operability is realized. From this, it is possible to reduce the production cost by improving the operability and reducing the raw material cost by increasing the use amount of the recovered and recycled raw material.

  In the present invention, the polyamide polymer constituting the B layer is a mixed polyamide polymer of 99.5 to 0.5% by weight of an aliphatic polyamide polymer and 0.5 to 99.5% by weight of a semi-aromatic polyamide polymer. By setting it as a composition, it is possible to prevent cohesive failure inside the film due to an impact at the time of dropping the bag-made product, and to bring a bag-breaking preventing effect at the time of dropping the bag-made product after filling the contents.

  Further, the polyamide polymer constituting the B layer is composed of a mixed polyamide polymer composed of 99.5 to 0.5% by weight of an aliphatic polyamide polymer and 0.5 to 99.5% by weight of a semi-aromatic polyamide polymer; By doing so, unevenness is formed on the surface of the B layer, and slipperiness to prevent blocking or the like during bag making is given.

  Among them, the polyamide polymer constituting the B layer is a mixed polyamide polymer of an aliphatic polyamide polymer and a semi-aromatic polyamide polymer, and 99.5 to 50.0% by weight of the aliphatic polyamide polymer and a semi-aromatic polyamide. In the case of a mixed polyamide polymer composition of 0.5 to 50.0% by weight of the polymer, the mixed polyamide polymer constituting the B layer is relatively flexible, so that the laminated biaxial stretching of the present invention The polyamide film as a whole is more effective in expressing bending fatigue resistance. However, since the mixed polyamide polymer constituting the B layer is flexible, when the thickness of the B layer is thin, the propagation of the impact generated at the time of dropping may not be sufficiently prevented. A bag may be generated. Therefore, as described above, when the mixed amount of the semi-aromatic polyamide polymer is small in the mixed polyamide polymer of the aliphatic polyamide polymer and the semi-aromatic polyamide polymer, the B layer on the side to be bonded to the sealant material The thickness is more preferably 2 μm or more.

  As described above, in the configuration in which the bending fatigue resistance of the laminated biaxially stretched polyamide film of the present invention is emphasized, the blend ratio of the aliphatic polyamide polymer and the semi-aromatic polyamide polymer of the polyamide polymer constituting the B layer Is a mixed polyamide polymer of 99.5 to 0.5% by weight of an aliphatic polyamide polymer and 0.5 to 99.5% by weight of a semi-aromatic polyamide polymer, in particular, an aliphatic polyamide polymer 99 A mixed polyamide polymer of ~ 90% by weight and 1-10% by weight of semi-aromatic polyamide polymer is preferred.

  On the other hand, when the mixed polyamide polymer constituting the B layer is a mixed polyamide polymer of an aliphatic polyamide polymer and a semi-aromatic polyamide polymer and the amount of the mixed semi-aromatic polyamide polymer is large, that is, In the case of a mixed polyamide polymer composition of 0.5 to 50.0% by weight of the polymer and 99.5 to 50.0% by weight of the semi-aromatic polyamide polymer, the mixed polyamide polymer constituting the B layer Since it becomes hard, the laminated biaxially stretched polyamide-based film of the present invention as a whole is effective in preventing the propagation of impacts that occur when dropped, and effective in the expression of bag-breaking prevention. Compared to the layer configuration with a high content of the aliphatic polyamide polymer, the effect of developing the bending fatigue resistance is reduced when the layer B is thick with a resin configuration with a high content of semi-aromatic polyamide polymer. . Therefore, in the case of the B layer structure having a large semi-aromatic polyamide polymer content, the B layer thickness is reduced, the occupation ratio of the A layer thickness to the total film thickness is increased, and the bag breakage prevention property and the good bending fatigue resistance are achieved. compatible. In this case, the thickness of the A layer is 20 to 96% of the total thickness of the A layer and the B layer, and the bag breakage preventing property and good bending fatigue resistance are within the range of the layer configuration in which the thickness of the B layer is at least 1 μm or more. A configuration that achieves compatibility can be selected.

  Further, when the mixed polyamide polymer constituting the B layer is a mixed polyamide polymer of an aliphatic polyamide polymer and a semi-aromatic polyamide polymer and the amount of the semi-aromatic polyamide polymer is large, that is, the aliphatic polyamide polymer is mixed. In the case of a composition of a mixed polyamide polymer of 0.5 to 50.0% by weight of the blend and 99.5 to 50.0% by weight of the semi-aromatic polyamide polymer, the layer B contains a metaxylylene group constituting Due to the low hygroscopicity of the polyamide polymer, surface slipperiness caused by absorbing moisture in the atmosphere is prevented, generation of wrinkles due to moisture absorption, etc. is prevented, and a laminated biaxially stretched polyamide film having the above structure is produced. When used for bag processing, the above-described excellent bag-breaking prevention property and bending fatigue resistance can be achieved at the same time, and good handling properties can be provided.

  The aliphatic polyamide polymer constituting the B layer of the laminated biaxially stretched polyamide film of the present invention can be used as a film molding material and is not particularly limited as long as it is suitable for forming the above structure. Is included. For example, aliphatic polyamide homopolymers such as nylon 6, nylon 6,6, nylon 12, nylon 6,10, or the like, or a copolymer of 10% by weight or less, preferably 1-10% by weight of monomers copolymerizable therewith For example, an aliphatic polyamide copolymer such as nylon 6/6 · 6 copolymer, nylon 6/12, nylon 6/6 · 10 copolymer, nylon 6/6/6 · 10 copolymer, etc. A small amount of aromatics, which is composed mainly of a representative aliphatic polyamide or ε-caprolactam and copolymerized with a nylon salt of hexamethylenedimine and isophthalic acid or a nylon salt of metaxylylenediamine and adipic acid. Polyamide copolymers containing can be used.

  The semi-aromatic polyamide polymer constituting the B layer is not particularly limited and includes a wide range. More specifically, a metaxylylene group-containing polyamide polymer, a phthalic acid group-containing polyamide polymer, and the like can be given. Semi-aromatic polyamide polymers can be used alone or in combination of two or more. The above-mentioned metaxylylene group-containing polyamide polymer includes metaxylylenediamine or mixed xylylenediamine composed of metaxylylenediamine and paraxylylenediamine as a main diamine component, and an α, ω-fat having 6 to 12 carbon atoms. In the metaxylylene group-containing polyamide polymer having an aromatic dicarboxylic acid as the main dicarboxylic acid component, paraxylylenediamine is preferably 30% or less of the total xylylenediamine, and is composed of xylylenediamine and an aliphatic dicarboxylic acid. It is preferable that the structural unit is at least 70 mol% or more in the molecular chain.

  Moreover, as said phthalic acid group containing polyamide polymer which comprises B layer, it has a C6-C12 alpha, omega-aliphatic diamine as the main diamine component, and consists of terephthalic acid or terephthalic acid and isophthalic acid. A phthalic acid group-containing polyamide polymer containing mixed phthalic acid as a main dicarboxylic acid component. Alternatively, a phthalic acid group-containing polyamide polymer or a polyamide copolymer obtained by copolymerizing an aliphatic polyamide or ε-caprolactam with a nylon salt composed of phthalic acid and an aliphatic diamine as described above can be used. In this case, the aliphatic polyamide component is preferably 30% or less in the copolymer polyamide polymer.

  In the polyamide polymer constituting the layer A and / or the layer B of the laminated biaxially stretched polyamide film of the present invention, an aliphatic amide and / or a fatty acid bisamide can be contained for the purpose of imparting slipperiness. Examples of the aliphatic amide and / or fatty acid bisamide contained in the polyamide polymer constituting the A layer and / or the B layer of the laminated biaxially stretched polyamide film of the present invention include erucic acid amide, stearic acid amide, ethylene bis stearin. Acid amide, ethylene bis oleic acid amide, etc. are mentioned.

  In this case, the content of the fatty acid amide and / or the fatty acid bisamide contained in the polyamide polymer constituting the A layer and / or the B layer is preferably 0.01 to 0.40% by weight, more preferably. 0.05 to 0.2% by weight. When the content of the fatty acid amide and / or the fatty acid bisamide is less than 0.01% by weight, the slipperiness is poor, and the processing suitability in printing or laminating becomes poor. Bleeding may cause spots on the surface, which is undesirable in terms of quality.

The laminated biaxially stretched polyamide film of the present invention has excellent bending fatigue resistance under normal temperature and low temperature environments, and excellent impact resistance, and also has good workability such as printing, laminating and bag making. It is. Furthermore, when used as a packaging material for food packaging, etc., it is effective in preventing bag breakage during transportation and storage of products, and also effective in preventing large bags from falling for business use. A laminated biaxially oriented polyamide film suitable for packaging materials.
In particular, it was found that for use as a large weight bag for business use etc., it is desirable that the impact strength is 0.95 J or more, the number of pinholes is 5 or less, and the laminate strength is 5.5 N / 15 mm or less. .
At this time, if the impact strength is 1.2 J, the number of pinholes is 0, and the laminate strength is 7 N / 15 mm, it is sufficient for use as a large-sized heavy bag for business use.

  The thickness of the laminated biaxially stretched polyamide film of the present invention is not particularly limited, but when used as a packaging material, it is usually 100 μm or less, and generally has a thickness of 5 to 50 μm.

  There are no particular restrictions on the method of mixing the various polyamide polymers constituting the A layer and the B layer, the thermoplastic elastomer, etc. Usually, a chip-shaped polymer is mixed using a V-type blender and then melted. A molding method is used.

  The polyamide polymer constituting the A layer and the B layer of the laminated biaxially stretched polyamide film of the present invention may include other thermoplastic resins as necessary, for example, polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate. A polyester polymer such as polyethylene and a polyolefin polymer such as polyethylene and polypropylene may be contained within a range that does not impair the properties thereof.

  Further, various additives such as an antistatic agent, an antifogging agent, an ultraviolet absorber, a dye, and a pigment are contained in one or both of the A layer and / or the B layer made of a polyamide polymer as necessary. be able to.

  The laminated biaxially stretched polyamide film of the present invention can be produced by a known production method. For example, the polymer constituting each layer is melted by using a separate extruder and manufactured by coextrusion from one die, and the polymer constituting each layer is separately melt-extruded into a film and then laminated. Arbitrary known methods such as a method of laminating and a combination thereof can be adopted, and as a stretching method, a known method such as a flat sequential biaxial stretching method, a flat simultaneous axial stretching method, a tubular method, etc. Is stretched 2 to 5 times in the longitudinal direction and 3 to 6 times in the transverse direction, and heat-fixed if necessary. Thus, the transparency, oxygen gas barrier properties and processability of the laminated film can be improved.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited to the following examples. The film was evaluated by the following measurement method.

(1) Impact strength A film impact tester manufactured by Toyo Seiki Seisakusho was used, and the measurement was performed in an environment of a temperature of 23 ° C. and a relative humidity of 65%.

(2) Bending fatigue resistance (number of pinholes)
Using a gelbo flex tester manufactured by Rigaku Corporation, the bending fatigue resistance was measured by the following method.
After applying a polyester adhesive to the film produced in the examples, 40 μm of a linear low density polyethylene film (L-LDPE film: L4102, manufactured by Toyobo Co., Ltd.) is dry-laminated and aged for 3 days in a 40 ° C. environment. A laminated film was obtained. The obtained laminate film is cut into 12 inches × 8 inches to form a cylindrical shape with a diameter of 3.5 inches, and one end of the cylindrical film is fixed to the fixed head side of the gelboflex tester and the other end is fixed to the movable head side. The initial gripping interval was 7 inches.
At the first 3.5 inches of the stroke, a twist of 440 degrees was given, and then 2.5 inches, a bending fatigue was performed 500 times at a speed of 40 times / min. The number of pinholes that occurred was counted. The measurement was performed in an environment of 5 ° C.

(3) Laminate strength The laminate strength was measured in order to grasp the cohesive fracture resistance in the film thickness direction.
After applying a polyester-based adhesive to the film produced in the example, a linear low density polyethylene film (L-LDPE: manufactured by Toyobo Co., Ltd., L4102: thickness 40 μm) is dry-laminated and aged in an environment at 40 ° C. for 3 days. To make a laminate film. The laminate film was cut into strips for measuring the laminate strength, one end was peeled off at the interface between the polyamide-based laminated biaxially stretched film and the linear low density polyethylene film, and the laminate strength was measured.

Example 1
An unstretched sheet having the following constitution was obtained using a two-type, three-layer coextrusion T-die facility. In the configuration of B layer / A layer / B layer, the total thickness of the unstretched sheet is 190 μm, and the thickness ratio of the A layer to the total thickness is 70%.
Composition composing layer A: Nylon 6 (Toyobo Co., Ltd., T814) is 95.9% by weight and Ny-12 is a polyamide-based block copolymer (Arkema, PEBAX4033SN01) containing 4% by weight. A mixed polymer composition comprising 0.1% by weight of a phenolic antioxidant (manufactured by Ciba Specialty Chemicals, Irganox 1010).
Composition constituting layer B: Nylon 6 is 96.85% by weight, polymetaxylene adipamide (Toyobo Co., Ltd., T600) is 3.0% by weight, and high fatty acid amide is 0.15% by weight Polymer composition.

  The obtained unstretched sheet was stretched 3.15 times in the longitudinal direction and then stretched 3.8 times in the transverse direction to produce a 15 μm biaxially stretched film. Further, a linear low density polyethylene film (L -LDPE film: Toyobo Co., Ltd., L4102) Corona discharge treatment was performed on the surface of the B layer on the side to be dry laminated with 40 μm. The impact strength, the number of pinholes, and the laminate strength of the obtained biaxially stretched film were measured. The results are shown in Table 1.

(Example 2)
A biaxially stretched film was obtained in the same manner as in Example 1 except that it was changed as follows in the description of Example 1.
Composition constituting layer A: Nylon 6 (manufactured by Toyobo Co., Ltd., T814) is 89.9% by weight, and polyamide-based block copolymer having Ny-12 as a polyamide component (Arkema, PEBAX4033SN01) is 10% by weight. And a mixed polymer composition containing 0.1% by weight of a phenolic antioxidant.

  The impact strength, the number of pinholes, and the laminate strength of the obtained biaxially stretched film were measured. The results are shown in Table 1.

(Example 3)
A biaxially stretched film was obtained in the same manner as in Example 1 except that it was changed as follows in the description of Example 1.
Composition constituting layer A: Nylon 6 (manufactured by Toyobo Co., Ltd., T814) is 83.9% by weight, and polyamide-based block copolymer having Ny-6 as a polyamide component (Arkema, PEBAX MH1657) is 16% by weight. %, And a mixed polymer composition containing 0.1% by weight of a phenolic antioxidant (manufactured by Ciba Specialty Chemicals, Irganox 1010).

  The impact strength, the number of pinholes, and the laminate strength of the obtained biaxially stretched film were measured. The results are shown in Table 1.

Example 4
A biaxially stretched film was obtained in the same manner as in Example 1 except that it was changed as follows in the description of Example 1.
Composition constituting layer A: Nylon 6 (manufactured by Toyobo Co., Ltd., T814) 89.9% by weight and ethylene-methacrylic acid copolymer (manufactured by Mitsui Deyupon Polychemical Co., Ltd., Nucrel N0903HC), 10% by weight, Furthermore, a mixed polymer composition containing 0.1% by weight of a phenolic antioxidant (manufactured by Ciba Specialty Chemicals, Irganox 1010).

  The impact strength, the number of pinholes, and the laminate strength of the obtained biaxially stretched film were measured. The results are shown in Table 1.

(Example 5)
A biaxially stretched film was obtained in the same manner as in Example 1 except that it was changed as follows in the description of Example 1.
Composition constituting layer A: Nylon 6 (Toyobo Co., Ltd., T814) was 89.9% by weight and ethylene-ethyl acrylate copolymer (Mitsui / Dyupon Polychemical Co., Ltd., EVAFLEX-EEA A-703) A mixed polymer composition containing 10% by weight and 0.1% by weight of a phenolic antioxidant (Irganox 1010, manufactured by Ciba Specialty Chemicals).

  The impact strength, the number of pinholes, and the laminate strength of the obtained biaxially stretched film were measured. The results are shown in Table 1.

(Example 6)
A biaxially stretched film was obtained in the same manner as in Example 1 except that it was changed as follows in the description of Example 1.
Composition constituting layer A: Nylon 6 (Toyobo Co., Ltd., T814) is 89.9% by weight and metal ion-containing ethylene-methacrylic acid copolymer (Mitsui / Dyupon Polychemical Co., Ltd., High Milan 1605) is 10 A mixed polymer composition containing 0.1% by weight of a phenolic antioxidant (manufactured by Ciba Specialty Chemicals, Irganox 1010).

  The impact strength, the number of pinholes, and the laminate strength of the obtained biaxially stretched film were measured. The results are shown in Table 1.

(Example 7)
A biaxially stretched film was obtained in the same manner as in Example 1 except that it was changed as follows in the description of Example 1.
Thickness ratio of layer A to total thickness: 81%
Composition constituting layer A: Nylon 6 (manufactured by Toyobo Co., Ltd., T814) is 95.9% by weight, and polyamide-based block copolymer having Ny-12 as a polyamide component (Arkema, PEBAX2533SN01) is 4% by weight. And 0.1% by weight of a phenolic antioxidant (Irganox 1010, manufactured by Ciba Specialty Chemicals).
Composition constituting layer B: Nylon 6 (Toyobo Co., Ltd., T814) is 49.85% by weight, polymetaxylene adipamide (Mitsubishi Gas Chemical Co., Ltd., S6007) is 50% by weight, and high fatty acid amide is A polymer composition comprising 0.15% by weight.

  The impact strength, the number of pinholes, and the laminate strength of the obtained biaxially stretched film were measured. The results are shown in Table 1.

(Example 8)
A biaxially stretched film was obtained in the same manner as in Example 1 except that it was changed as follows in the description of Example 1.
Ratio of thickness of layer A to total thickness: 86%
Composition constituting layer A: Nylon 6 (Toyobo Co., Ltd., T814) is 94.9% by weight and Ny-12 is a polyamide-based block copolymer having a polyamide component (Arkema, PEBAX2533SN01) 5% by weight And 0.1% by weight of a phenolic antioxidant (Irganox 1010, manufactured by Ciba Specialty Chemicals).
Composition constituting layer B: Nylon 6 (Toyobo Co., Ltd., T814) is 9.85% by weight, polymetaxylene adipamide (Mitsubishi Gas Chemical Co., Ltd., S6007) is 90% by weight, and high fatty acid amide is A polymer composition comprising 0.15% by weight.

  The impact strength, the number of pinholes, and the laminate strength of the obtained biaxially stretched film were measured. The results are shown in Table 1.

(Comparative Example 1)
A biaxially stretched film was obtained in the same manner as in Example 1 except that it was changed as follows in the description of Example 1. A single-layer extrusion T-die facility was used to obtain an unstretched sheet having the following configuration. With a single layer configuration, the total thickness of the unstretched sheet is 190 μm.
Composition comprising: Nylon 6 (Toyobo Co., Ltd., T814) 96.85 wt%, Polymetaxylylene Adipamide (Toyobo Co., Ltd., T600) 3.0 wt%, and High Fatty Acid Amide 0 A polymer composition comprising 15% by weight.

  The impact strength, the number of pinholes, and the laminate strength of the obtained biaxially stretched film were measured. The results are shown in Table 1.

(Comparative Example 2)
A biaxially stretched film was obtained in the same manner as in Example 1 except that it was changed as follows in the description of Example 1. A single-layer extrusion T-die facility was used to obtain an unstretched sheet having the following configuration. With a single layer configuration, the total thickness of the unstretched sheet is 190 μm.
Composition: Nylon 6 (Toyobo Co., Ltd., T814) is 96.85% by weight and Ny-12 is a polyamide-based block copolymer (Arkema, PEBAX4033SN01) is 3.0% by weight, And a polymer composition comprising 0.15% by weight of a high fatty acid amide.

  The impact strength, the number of pinholes, and the laminate strength of the obtained biaxially stretched film were measured. The results are shown in Table 1.

(Comparative Example 3)
A biaxially stretched film was obtained in the same manner as in Example 1 except that it was changed as follows in the description of Example 1.
Ratio of thickness of layer A to total thickness: 86%
Composition constituting layer A: Nylon 6 (manufactured by Toyobo Co., Ltd., T814) is 95.9% by weight and Ny-12 is a polyamide block copolymer (manufactured by Arkema, PEBAX4033SN01) having a polyamide component of 4.0. A mixed polymer composition comprising 0.1% by weight of a phenolic antioxidant (manufactured by Ciba Specialty Chemicals, Irganox 1010).

  The impact strength, the number of pinholes, and the laminate strength of the obtained biaxially stretched film were measured. The results are shown in Table 1.

(Comparative Example 4)
A biaxially stretched film was obtained in the same manner as in Example 1 except that it was changed as follows in the description of Example 1.
Thickness ratio of layer A to total thickness: 73%
Composition constituting layer A: Nylon 6 (Toyobo Co., Ltd., T814) is 89.9% by weight and Ny-12 is a polyamide-based block copolymer (manufactured by Arkema, PEBAX4033SN01) is 10.0. A mixed polymer composition containing 0.1% by weight of a phenolic antioxidant (Irganox 1010, manufactured by Ciba Specialty Chemicals).
Composition constituting layer B: 49.85% by weight of nylon 6 (manufactured by Toyobo Co., Ltd., T814), 50% by weight of polymetaxylene adipamide (manufactured by Mitsubishi Gas Chemical Company, S6007), and 0 in high fatty acid amide A polymer composition comprising 15% by weight.

  The impact strength, the number of pinholes, and the laminate strength of the obtained biaxially stretched film were measured. The results are shown in Table 1.

(Comparative Example 5)
A biaxially stretched film was obtained in the same manner as in Example 1 except that it was changed as follows in the description of Example 1.
Ratio of thickness of layer A to total thickness: 86%
Composition constituting layer A: Nylon 6 (Toyobo Co., Ltd., T814) is 89.9% by weight and Ny-12 is a polyamide-based block copolymer (manufactured by Arkema, PEBAX4033SN01) is 10.0. A mixed polymer composition comprising 0.1% by weight of a phenolic antioxidant (manufactured by Ciba Specialty Chemicals, Irganox 1010).
Composition constituting layer B: Nylon 6 (Toyobo Co., Ltd., T814) is 49.85% by weight, polymetaxylene adipamide (Mitsubishi Gas Chemical Co., Ltd., S6007) is 50% by weight, and high fatty acid amide is A polymer composition comprising 0.15% by weight.

  The impact strength, the number of pinholes, and the laminate strength of the obtained biaxially stretched film were measured. The results are shown in Table 1.

  The laminated biaxially stretched polyamide film of the present invention has been described based on a plurality of examples. However, the present invention is not limited to the configurations described in the above examples, and the configurations described in the respective examples. The configuration can be changed as appropriate without departing from the spirit of the invention, for example, by appropriately combining them.

  The laminated biaxially stretched polyamide film of the present invention has characteristics such as excellent impact resistance and bending fatigue resistance, particularly bending fatigue resistance in a low temperature environment. In addition to being suitable for use in materials, for example, it can also be used in large weight bags for business use.

Claims (9)

  On at least one surface of the layer A composed of a mixed polymer of 97 to 80% by weight of an aliphatic polyamide polymer and 3 to 20% by weight of a thermoplastic elastomer, 99.5 to 0.5% by weight of an aliphatic polyamide polymer and B layer composed of mixed polyamide polymer with 0.5-99.5% by weight of semi-aromatic polyamide polymer is laminated, impact strength is 1.5J or more, pinhole number is 5 or less, laminate strength Is a laminated biaxially stretched polyamide-based film, characterized by being 5.5 N / 15 mm or less.   The laminated biaxially oriented polyamide film according to claim 1, wherein the thickness of the A layer is 20 to 93% of the total thickness of the A layer and the B layer, and the thickness of the B layer is at least 1 µm or more.   The laminate 2 according to claim 1 or 2, wherein the thermoplastic elastomer constituting the A layer is one or more elastomers selected from polyamide elastomers, polyolefin elastomers, and ionomer polymers. Axial stretched polyamide film.   The layer B is composed of a mixed polyamide polymer of 99.5 to 50.0% by weight of an aliphatic polyamide polymer and 0.5 to 50.0% by weight of a semi-aromatic polyamide polymer, The laminated biaxially stretched polyamide film according to 2 or 3.   The B layer is composed of a mixed polyamide polymer of 99.5 to 50.0% by weight of a semi-aromatic polyamide polymer and 0.5 to 50.0% by weight of an aliphatic polyamide polymer, The laminated biaxially stretched polyamide film according to 2 or 3.   The polyamide polymer constituting the A layer and / or the B layer contains 0.01 to 0.40% by weight of aliphatic amide and / or aliphatic bisamide. Or a laminated biaxially stretched polyamide-based film according to 5;   7. The laminated biaxial stretching according to claim 1, 2, 3, 4, 5 or 6, wherein the mixed polymer constituting the A layer contains 0.01 to 0.1% by weight of an antioxidant. Polyamide film.   The laminated biaxially stretched polyamide film according to claim 7, wherein the antioxidant is a phenolic antioxidant.   The laminated biaxially stretched polyamide according to claim 8, wherein the phenolic antioxidant is one or more phenolic compounds selected from a completely hindered phenolic compound or a partially hindered phenolic compound. Film.