Polyamide multilayer oriented film

Abstract

The present invention provides a multilayer stretched polyamide-based film that has excellent resistance to pinholes caused by bending. The layer A contains a polyamide resin and contains 3% by weight or less of components other than the polyamide resin. The layer B contains 85 to 99% by weight of the polyamide resin and 1 to 15% by weight of the polyester elastomer. and a C layer containing a barrier resin.

Description

[Technical field]

[0001] The present invention relates to a multilayer stretched polyamide-based film. [Background technology]

[0002] Conventionally, films containing nylon resin have been widely used in various fields as films with gas barrier properties, toughness, etc. For example, Such films are widely used for packaging purposes.

[0003] This film is used, for example, as a packaging film for food products distributed in the market, but pinholes may occur during transportation, transport, etc. These pinholes result in the excellent gas barrier properties of the film being impaired. Therefore, the market demands further improvement in toughness, especially pinhole resistance.

[0004] Pinholes in films are caused by bending or by wear caused by repeated contact.

[0005] Generally, if the nylon resin layer is hard, pinholes due to wear caused by repeated contact are unlikely to occur, but pinholes due to bending are likely to occur. On the other hand, if the nylon resin layer is soft, pinholes due to bending are unlikely to occur, but pinholes due to wear caused by repeated contact are likely to occur.

[0006] Therefore, there is a strong demand for a film that has excellent pinhole resistance against bending or repeated contact.

[0007] In order to solve this problem, the present applicant has already developed a polyamide-based film having at least a polyamide layer containing a polyamide and a flex resistance agent (Patent Document 1).

[0008] However, there is a demand for further improvement, and there is a need for the development of a multilayer stretched polyamide-based film that is more excellent in resistance to pinholes caused by bending and repeated contact. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2017-2114 A Summary of the Invention [Problem to be solved by the invention]

[0010] An object of the present invention is to provide a multilayer stretched polyamide-based film that is excellent in resistance to pinholes caused by bending and repeated contact. [Means for solving the problem]

[0011] As a result of intensive research conducted by the present inventors to solve the above problems, it has been discovered that in a polyamide-based multilayer stretched film, the A layer contains a polyamide-based resin, and the B layer contains a polyamide-based resin and a polyester-based resin. The inventors discovered that by having at least layer B containing an elastomer and layer C containing a barrier resin, this polyamide-based multilayer stretched film has excellent pinhole resistance caused by bending and repeated contact, which led to the completion of the present invention.

[0012] That is, the present invention provides the following multilayer stretched polyamide-based film.

[0013] Section 1. A layer contains a polyamide resin and contains 3% by weight or less of components other than the polyamide resin. A multi-layer stretched polyamide-based film having at least a layer B containing 85 to 99% by weight of an amide-based resin and 1 to 15% by weight of a polyester-based elastomer, and a layer C containing a barrier resin.

[0014] Section 2. 2. The polyamide according to claim 1, wherein the layer A contains an aliphatic polyamide and an aromatic polyamide. Multi-layer oriented film.

[0015] Section 3. The barrier resin is an ethylene-vinyl alcohol copolymer or an aromatic polyamide. 3. The multilayer stretched polyamide-based film according to item 1 or 2. Effect of the Invention

[0016] The multilayer stretched polyamide-based film of the present invention has excellent resistance to pinholes caused by bending and repeated contact.

[0017] The multilayer stretched polyamide-based film of the present invention has excellent transparency. [Brief description of the drawings]

[0018] [Figure 1] 1 shows a schematic diagram of a measuring device used to evaluate pinholes caused by repeated contact. [Diagram 2] An example of a cone-shaped aluminum jig is shown below. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] (1) Multilayer oriented polyamide film The polyamide-based multilayer stretched film of the present invention has at least layer A containing a polyamide-based resin and containing 3 wt % or less of components other than polyamide-based resin, layer B containing 85 to 99 wt % of polyamide-based resin and 1 to 15 wt % of polyester-based elastomer, and layer C containing a barrier resin.

[0020] The multilayer stretched polyamide-based film of the present invention has excellent resistance to pinholes caused by bending and repeated contact.

[0021] The multilayer stretched polyamide-based film of the present invention is further excellent in transparency.

[0022] The polyamide film of the present invention will be described in detail below.

[0023] (1-1) Layer A (PA layer 1) of polyamide multilayer oriented film The layer A of the multilayer stretched polyamide-based film of the present invention contains a polyamide-based resin. The content of components other than the vinyl resin is 3% by weight or less.

[0024] Polyamide Resin The polyamide resin is not particularly limited, and aliphatic polyamides, aromatic polyamides, etc. can be preferably used.

[0025] Layer A is an aliphatic polyamide because it has excellent pinhole resistance caused by bending and repeated contact. It is preferred that it contains mido.

[0026] Aliphatic Polyamide Aliphatic polyamides include aliphatic nylons and copolymers thereof.

[0027] Polycapramide (nylon-6), poly-ω-aminoheptanoic acid (nylon-7), poly-ω-aminononanoic acid (nylon-9), polyundecaneamide (nylon-11), polylauryl It is preferable to use lactam (nylon-12) or the like.

[0028] It is preferable to use polyethylene diamine adipamide (nylon-2,6), polytetramethylene adipamide (nylon-4,6), polyhexamethylene adipamide (nylon-6,6), polyhexamethylene sebacamide (nylon-6,10), polyhexamethylene dodecamide (nylon-6,12), polyoctamethylene adipamide (nylon-8,6), polydecamethylene adipamide (nylon-10,8), etc.

[0029] Caprolactam / lauryl lactam copolymer (nylon-6 / 12), caprolactam / ω-aminononanoic acid copolymer (nylon-6 / 9), caprolactam / hexamethylenediammonium adipate copolymer (nylon-6 / 6,6), lauryl lactam / hexamethylenediammonium adipate copolymer (nylon-6 / 6,6), It is preferable to use ammonium adipate copolymer (nylon-12 / 6,6) or the like.

[0030] Ethylenediamine adipamide / hexamethylenediammonium adipate copolymer (nylon-2,6 / 6,6), caprolactam / hexamethylenediammonium adipate / hexamethylenediammonium adipate copolymer It is preferable to use samethylenediammonium sebacate copolymer (nylon-6,6 / 6,10), ethyleneammonium adipate / hexamethylenediammonium adipate / hexamethylenediammonium sebacate copolymer (nylon-6 / 6,6 / 6,10), or the like.

[0031] One of the above aliphatic polyamides may be used, or two or more of the above aliphatic polyamides may be used in combination.

[0032] Preferred aliphatic polyamides include nylon-6, nylon-6,6, nylon-6 / 6,6 ( A copolymer of nylon 6 and nylon 6,6 is preferred. Nylon-6 and nylon-6 / 6,6 are more preferred, and nylon-6 is particularly preferred.

[0033] As the two or more kinds of aliphatic polyamides, a combination of nylon-6 and nylon-6 / 6,6 is preferred. It is preferable that the nylon-6 is contained in a weight ratio of about 50 to 95, and the nylon-6 / 6,6 is contained in a weight ratio of about 50 to 5.

[0034] Aromatic Polyamide The polyamide-based resin may further include an aromatic polyamide.

[0035] Examples of aromatic polyamides include crystalline aromatic polyamides obtained by polycondensation reaction of aromatic diamines such as metaxylenediamine and paraxylenediamine with dicarboxylic acids or derivatives thereof such as adipic acid, suberic acid, sebacic acid, cyclohexanedicarboxylic acid, terephthalic acid, and isophthalic acid.

[0036] As the aromatic polyamide, preferably polymetaxylylene adipamide (MX-nylon) Specific examples of the crystalline aromatic polyamide include S-6001, S-6007, and S-6121 (all manufactured by Mitsubishi Gas Chemical Company, Inc.).

[0037] Examples of aromatic polyamides include non-crystalline aromatic polyamides (amorphous nylons) obtained by polycondensation reaction between an aliphatic diamine such as hexamethylenediamine and a dicarboxylic acid such as terephthalic acid or isophthalic acid or a derivative thereof.

[0038] The amorphous aromatic polyamide is preferably a copolymer of hexamethylenediamine-terephthalic acid-hexamethylenediamine-isophthalic acid. A specific example is Sealer PA (manufactured by DuPont-Mitsui Polychemicals Co., Ltd.).

[0039] Preferred composition of polyamide resin The content of aliphatic polyamide (such as nylon 6) in the polyamide resin is preferably poly. The amount of the amide is about 80 to 100% by weight, and more preferably about 80 to 99% by weight. By setting the content of the aliphatic polyamide in the polyamide within the above range, the pinhole resistance of the polyamide film can be improved.

[0040] When the polyamide-based resin contains an aliphatic polyamide and an aromatic polyamide, the polyamide-based film of the present invention can exhibit better stretch-formability.

[0041] Preferred combinations of aliphatic polyamides and aromatic polyamides include a combination of nylon-6 and a crystalline aromatic polyamide (e.g., MX-nylon), a combination of nylon-6 and an amorphous aromatic polyamide (e.g., MX-nylon), A combination with polyamide (amorphous nylon) is also possible.

[0042] Aromatic polyamides in polyamide resins (MX-nylon or amorphous nylon, etc.) The content is preferably about 0 to 20% by weight, and more preferably about 1 to 20% by weight, based on 100% by weight of the amount of polyamide.

[0043] Preferred relative viscosity of polyamide resin As a polyamide resin, it has a 96% H 2 SO 4 It is preferable to use a liquid having a relative viscosity of 2.0 to 4.5 measured under the conditions of 1.0 g / 100 ml and 25° C. It is more preferable to use one having a relative viscosity (JIS K6920) of 3.0 to 4.5. The relative viscosity (JIS K6920) of the polyamide resin is more preferably 3.0 to 4.2. When the relative viscosity of the polyamide satisfies this range, the multilayer stretched polyamide film has good pinhole resistance due to bending.

[0044] When two or more polyamide resins are mixed, the relative viscosity of the polyamide resins is: The relative viscosity of each of the polyamides to be mixed is measured, and the weighted average value is taken as the relative viscosity of the mixed polyamide.

[0045] Components other than polyamide resin Layer A is made of components other than polyamide resin from the viewpoint of pinhole resistance caused by repeated contact. It is preferable that the content of components other than the polyamide resin is 3% by weight or less. If the content of components other than the polyamide resin exceeds 3% by weight, the pinhole resistance deteriorates due to repeated contact, which is not preferable.

[0046] In the multilayer stretched polyamide-based film of the present invention, the above-mentioned "Layer A containing a polyamide-based resin and containing 3% by weight or less of components other than the polyamide-based resin" means that Layer A contains 97% by weight or more of a polyamide-based resin. Alternatively, it may be expressed as "Layer A containing 97% by weight or more of polyamide resin."

[0047] Layer A may contain other additives as necessary within the range that does not impair the effects of the present invention. As other additives, antiblocking agents, lubricants, nucleating agents, antioxidants, etc. may be preferably used.

[0048] (1-2) Layer B (PA layer 2) of polyamide multilayer oriented film Layer B of the multilayer stretched polyamide-based film of the present invention contains 85 to 99% by weight of a polyamide-based resin and 1 to 15% by weight of a polyester-based elastomer. The multilayer stretched polyamide-based film of the present invention has excellent pinhole resistance (flex resistance) due to bending, particularly due to Layer B.

[0049] Polyamide Resin The polyamide resin is not particularly limited, and aliphatic polyamides, aromatic polyamides, etc. can be preferably used. Aliphatic polyamides are preferred from the viewpoint of superior pinhole resistance.

[0050] Aliphatic Polyamide Aliphatic polyamides include aliphatic nylons and copolymers thereof.

[0051] Polycapramide (nylon-6), poly-ω-aminoheptanoic acid (nylon-7), poly-ω-aminononanoic acid (nylon-9), polyundecaneamide (nylon-11), polylauryl It is preferable to use lactam (nylon-12) or the like.

[0052] It is preferable to use polyethylene diamine adipamide (nylon-2,6), polytetramethylene adipamide (nylon-4,6), polyhexamethylene adipamide (nylon-6,6), polyhexamethylene sebacamide (nylon-6,10), polyhexamethylene dodecamide (nylon-6,12), polyoctamethylene adipamide (nylon-8,6), polydecamethylene adipamide (nylon-10,8), etc.

[0053] Caprolactam / lauryl lactam copolymer (nylon-6 / 12), caprolactam / ω-aminononanoic acid copolymer (nylon-6 / 9), caprolactam / hexamethylenediammonium adipate copolymer (nylon-6 / 6,6), lauryl lactam / hexamethylenediammonium adipate copolymer (nylon-6 / 6,6), It is preferable to use ammonium adipate copolymer (nylon-12 / 6,6) or the like.

[0054] Ethylenediamine adipamide / hexamethylenediammonium adipate copolymer (nylon-2,6 / 6,6), caprolactam / hexamethylenediammonium adipate / hexamethylenediammonium adipate copolymer It is preferable to use samethylenediammonium sebacate copolymer (nylon-6,6 / 6,10), ethyleneammonium adipate / hexamethylenediammonium adipate / hexamethylenediammonium sebacate copolymer (nylon-6 / 6,6 / 6,10), or the like.

[0055] One of the above aliphatic polyamides may be used, or two or more of the above aliphatic polyamides may be used in combination.

[0056] Preferred aliphatic polyamides include nylon-6, nylon-6,6, nylon-6 / 6,6 ( A copolymer of nylon 6 and nylon 6,6 is preferred. Nylon-6 and nylon-6 / 6,6 are more preferred, and nylon-6 is particularly preferred.

[0057] Layer B contains 85 to 99% by weight of a polyamide resin, and as the polyamide resin, two or more kinds of aliphatic polyamides can be used in combination.

[0058] As the two or more kinds of aliphatic polyamides in the B layer, a combination of an aliphatic polyamide resin (such as nylon-6) and a polyamide copolymer (such as nylon-6 / 6,6) is preferable. For example, the B layer contains an aliphatic polyamide resin (such as nylon-6) at a weight ratio (weight %) of about 50 to 94, and the polyamide It is preferable that the resin contains about 5 to 40% by weight of a nylon copolymer (eg, nylon-6 / 6,6).

[0059] Aromatic Polyamide The polyamide-based resin may be a mixture of the above-mentioned aliphatic polyamide and aromatic polyamide, or may contain aromatic polyamide as an optional component.

[0060] When the polyamide-based resin contains an aliphatic polyamide and an aromatic polyamide, The polyamide-based multilayer stretched film can exhibit superior stretching film-forming properties.

[0061] Examples of aromatic polyamides include crystalline aromatic polyamides obtained by polycondensation reaction of aromatic diamines such as metaxylenediamine and paraxylenediamine with dicarboxylic acids or derivatives thereof such as adipic acid, suberic acid, sebacic acid, cyclohexanedicarboxylic acid, terephthalic acid, and isophthalic acid.

[0062] The aromatic polyamide is preferably a crystalline aromatic polyamide such as polymetaxylylene adipamide, etc. Specific examples of the crystalline aromatic polyamide include S-6001, S-6007, and S-6121 (all manufactured by Mitsubishi Gas Chemical Company, Inc.).

[0063] Furthermore, examples of the aromatic polyamide include non-crystalline aromatic polyamides (amorphous nylons) obtained by polycondensation reaction between an aliphatic diamine such as hexamethylenediamine and a dicarboxylic acid or a derivative thereof such as terephthalic acid or isophthalic acid.

[0064] The aromatic polyamide is preferably a copolymer of hexamethylenediamine-terephthalic acid-hexamethylenediamine-isophthalic acid. An example of such a sealant is Sealer PA (manufactured by DuPont-Mitsui Polychemicals Co., Ltd.).

[0065] Preferred combinations of aliphatic polyamides and aromatic polyamides include a combination of nylon-6 and a crystalline aromatic polyamide, and a combination of nylon-6 and a non-crystalline aromatic polyamide (amorphous nylon).

[0066] The content of the aliphatic polyamide in the polyamide-based resin of the layer B is preferably the amount of polyamide The content is 80 to 100% by weight, more preferably 90 to 100% by weight, based on 100% by weight of the polyamide. By setting the content of the aliphatic polyamide in the above range, the pinhole resistance of the polyamide-based film can be improved.

[0067] When the polyamide resin of the layer B contains an aliphatic polyamide and an aromatic polyamide, The content of aromatic polyamide in the polyamide is 100 parts by weight of polyamide as an optional component. The amount is preferably 0 to 20% by weight, and more preferably 0 to 10% by weight.

[0068] Preferred relative viscosity of polyamide resin As a polyamide resin, it has a 96% H 2 SO 4It is preferable to use one having a relative viscosity of 2.5 to 4.5 measured under conditions of 1.0 g / 100 ml and a temperature of 25° C. The relative viscosity (JIS K6920) of the polyamide resin is more preferably 3.0 to 4.5, and further preferably 3.2 to 4.2. When the relative viscosity of the polyamide satisfies this range, the polyamide multi-layer stretching The film has good pinhole resistance when bent.

[0069] When two or more polyamide resins are mixed, the relative viscosity of the polyamide resins is: The relative viscosity of each of the polyamides to be mixed is measured, and the weighted average value is taken as the relative viscosity of the mixed polyamide.

[0070] Polyester Elastomer The layer B of the multilayer stretched polyamide-based film of the present invention contains 1 to 15% by weight of a polyester-based elastomer, which functions as a flex resistance agent and can impart pinhole resistance due to flexing. can.

[0071] The polyester-based elastomer is a thermoplastic elastomer, which is a thermoplastic material having rubber-like elasticity.

[0072] In addition to the polyester elastomer, polyamide elastomers, polyolefin elastomers, polystyrene elastomers, polyurethane elastomers, polyvinyl chloride elastomers, ionomer polymers, etc. may be used in combination.

[0073] The polyester-based elastomer is used because it can further improve the pinhole resistance caused by bending of the polyamide-based multilayer stretched film of the present invention, and optionally, preferably, a polyamide-based elastomer or a polyolefin-based elastomer can be used, more preferably, a polyamide-based elastomer is used in combination.

[0074] In addition to polyester elastomers, other thermoplastic elastomers may be used alone or in combination with two or more other types. The above can be used in combination.

[0075] The polyester-based elastomer may be modified to the extent that the pinhole resistance caused by bending of the multilayer stretched polyamide-based film of the present invention is not reduced.

[0076] Modifications of polyester-based elastomers include, for example, modification by copolymerization or graft modification, and modification by imparting polar groups.

[0077] The polar group may be added 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. The polar group may be added by one type or a combination of multiple types. Therefore, the modified products to which a polar group has been added include, for example, epoxy modified products, carboxy modified products, acid anhydride modified products, hydroxy modified products, amino modified products, etc. of polyester-based elastomers.

[0078] The polyester elastomer may be a modified polyester elastomer, which is a saturated polyester thermoplastic elastomer containing a polyalkylene ether glycol segment modified with an unsaturated carboxylic acid or a derivative thereof.

[0079] Specifically, the content of the polyalkylene ether glycol segment is 58 to 73% by weight. This is a modified polyester elastomer obtained by modifying a certain saturated polyester thermoplastic elastomer with an unsaturated carboxylic acid or its derivative in the presence of a radical generator. Reactive groups are introduced by the graft reaction and terminal addition reaction of the unsaturated carboxylic acid or its derivative, improving the chemical bonding and hydrogen bonding properties with various resins.

[0080] The saturated polyester-based thermoplastic elastomer is a block copolymer consisting of a soft segment containing a polyalkylene ether glycol segment and a hard segment containing a polyester, and the content of the polyalkylene ether glycol segment in the polyester-based elastomer is about 58 to 73% by weight.

[0081] Examples of polyalkylene ether glycols constituting the soft segment include polyethylene glycol, poly(1,2 and 1,3-propylene ether) glycol, poly(tetrafluoroethylene) glycol, and the like. Poly(alkylene ether) glycol, poly(hexamethylene ether) glycol, etc. can be preferably used. The number average molecular weight of the polyalkylene ether glycol is preferably about 400 to 6,000.

[0082] Examples of unsaturated carboxylic acids or derivatives thereof include acrylic acid, maleic acid, and fumaric acid. and the like, their acid anhydrides, their esters, or their metal salts.

[0083] Examples of the radical generator include peroxides such as t-butyl hydroperoxide and cumene hydroperoxide, and azo compounds such as 2,2'-azobisisobutyronitrile (AIBN).

[0084] For 100 parts by weight of saturated polyester thermoplastic elastomer, It is preferable that the derivative is contained in an amount of 0.01 to 30 parts by weight, and the radical generator is contained in an amount of 0.001 to 3 parts by weight.

[0085] The method for preparing the modified polyester elastomer is not particularly limited, but it can be prepared by the method described in, for example, JP-A-2002-155135.

[0086] The melt flow rate (MFR) of the resulting modified polyester elastomer is preferably The MFR is preferably 40 to 300 g / 10 min. The MFR is a value measured under conditions of 230° C. and 2.16 kg by a measurement method in accordance with JIS K7210.

[0087] As the polyester elastomer, particularly preferred is a maleic anhydride modified polyester elastomer. A specific example of a commercially available modified polyester elastomer is Tefablock-GQ131 (manufactured by Mitsubishi Chemical Corporation).

[0088] A preferred polyamide-based elastomer as the optional thermoplastic elastomer is a polyamide-based block copolymer having a hard segment constituted by a polyamide component and a soft segment constituted by a polyoxyalkylene glycol component.

[0089] The polyamide components of the hard segments are (1) lactam and (2) ω-amino aliphatic carbo The polyamide component of the hard segment is specifically selected from the group consisting of lactams such as ε-caprolactam, aliphatic diamines such as aminoheptanoic acid, adipic acid, (3) aliphatic diamines and aliphatic dicarboxylic acids, or (4) aliphatic diamines and aromatic dicarboxylic acids. Examples of suitable dicarboxylic acids include aliphatic dicarboxylic acids such as terephthalic acid, and aromatic dicarboxylic acids such as terephthalic acid.

[0090] Examples of the polyoxyalkylene glycol constituting the soft segment of the polyamide block copolymer include polyoxytetramethylene glycol, polyoxyethylene glycol, and polyoxy-1,2-propylene glycol.

[0091] The melting point of the polyamide block copolymer is determined by the types and ratios of the hard segment constituted by the polyamide component and the soft segment constituted by the polyoxyalkylene glycol component, and is usually preferably in the range of 120 to 180°C.

[0092] Polyamide block copolymers are used as components of laminated biaxially oriented polyamide films. This improves the flexural fatigue resistance of the laminated biaxially oriented polyamide film, especially in low temperature environments. This is effective in improving resistance to bending fatigue.

[0093] Examples of polyolefin-based elastomers include resins obtained by graft-modifying or copolymerizing a polyolefin resin with an unsaturated carboxylic acid or an anhydride thereof.

[0094] Polyolefin resins that can be used as the base polymer for polyolefin elastomers include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1- Homopolymers of α-olefins such as decene, 1-dodecene, and 4-methyl-1-pentene. Random copolymers of one or more of these, block copolymers of two or more of these, ethylene and vinyl acetate and copolymers of ethylene and a polar monomer, such as a copolymer of ethylene and ethyl (meth)acrylate.

[0095] More specifically, examples of polyolefin resins that can be used as the base polymer include high-density polyethylene, medium-density polyethylene, high-pressure low-density polyethylene, linear low-density polyethylene (copolymer of ethylene and α-olefin having 3 or more carbon atoms), polypropylene (homopolymer, random polymer, block copolymer, etc.), poly-1-butene, poly-4-methyl-1-propylene, Examples of the copolymer include ethylene-vinyl acetate copolymer.

[0096] These may be produced using any catalyst system, for example, the linear low density polyethylene may be produced using a metallocene catalyst or a multi-site catalyst.

[0097] Polyolefin elastomers can be obtained by grafting an unsaturated carboxylic acid onto a polyolefin resin, which is a base polymer, or by copolymerizing and modifying an olefin with a small amount of an unsaturated carboxylic acid.

[0098] Examples of the unsaturated carboxylic acid or anhydride thereof used for grafting or copolymerization modification include acrylic acid, methacrylic acid, fumaric acid, maleic anhydride, itaconic anhydride, and norbornene-2,3-dicarboxylic anhydride.

[0099] In particular, acid anhydrides are preferred, with maleic anhydride being particularly preferred.

[0100] The polyolefin elastomer is preferably a maleic anhydride-modified ethylene copolymer. Examples of the maleic anhydride-modified ethylene copolymer include maleic anhydride graft-modified ethylene copolymer and maleic anhydride-ethylene copolymer. A partially saponified maleic anhydride-modified copolymer can be suitably used.

[0101] Polyamide resin and polyester elastomer content The content of polyamide resin in layer B is 85 to 99% by weight, with the total weight of layer B being 100% by weight. By satisfying this content range for the polyamide resin in layer B, the resistance to bending is improved. The content of the polyamide resin in the layer B is preferably 90 to 98% by weight.

[0102] The content of polyester elastomer in layer B is 100% by weight of the entire layer B. The polyester elastomer in layer B satisfies this content range, and thus the pinhole resistance due to bending is good. The content is preferably 2 to 10% by weight.

[0103] Layer B may contain other additives as necessary within the range that does not impair the effects of the present invention. As other additives, antiblocking agents, lubricants, nucleating agents, antioxidants, etc. may be preferably used.

[0104] The multilayer stretched polyamide-based film of the present invention has high resistance to pinholes caused by bending, particularly due to Layer B. Excellent resistance to bending.

[0105] (1-3) Layer C (barrier layer) of polyamide multilayer oriented film Layer C of the multilayer stretched polyamide-based film of the present invention contains a barrier resin.

[0106] The barrier resin is preferably an ethylene-vinyl alcohol copolymer (EVOH) and / or or aromatic polyamide. The barrier resin is preferably EVOH and / or polymethacrylate. Xylylene adipamide (MX-nylon), more preferably EVOH.

[0107] The multilayer stretched polyamide-based film of the present invention includes layer C, The film has excellent gas barrier properties. C layer is made of EVOH and polymetaxylylene adipamide. They may be used alone or in combination.

[0108] The ethylene-vinyl alcohol copolymer (EVOH) is not particularly limited. The ethylene content is preferably 55 mol % or less, more preferably 20 to 50 mol %, and further preferably 25 to 44 mol %.

[0109] The saponification degree of the vinyl acetate component of the EVOH is preferably 90 mol % or more, and more preferably is 95 mol % or more.

[0110] EVOH may further contain small amounts of comonomers, such as α-olefins such as propylene, isobutene, α-octene, α-dodecene, and α-octadecene; unsaturated carboxylic acids or derivatives thereof (e.g., salts, partial alkyl esters, complete alkyl esters, nitriles, amides, and anhydrides); and unsaturated sulfonic acids or salts thereof, within the scope of not adversely affecting the effects of the present invention.

[0111] The melt index (MI) of the EVOH is preferably 0.5 to 50 g / 10 min (210°C, 2,160 g load). ), and more preferably 1 to 35 g / 10 min (210° C., 2,160 g load). By satisfying this condition, the viscosity becomes sufficient for melt extrusion, and film-forming properties are excellent.

[0112] Commercially available EVOH products include, for example, DC3203FB and DT2904RB (both manufactured by Nippon Synthetic Chemical Industry Co., Ltd.).

[0113] Aromatic polyamides such as polymetaxylylene adipamide (MX-nylon) are preferably used. It is possible.

[0114] Examples of aromatic polyamides include S-6001, S-6007, and S-6121 (all manufactured by Mitsubishi Gas Chemical Co., Inc.).

[0115] The layer C, as a barrier layer, further contains modified ethylene within a range that does not adversely affect the effects of the present invention. It may contain other components such as vinyl acetate copolymers and methacrylic acid copolymer ionomers. When other components are contained in the C layer, the content of these components is usually EVOH and / or MX- The amount is preferably 15 parts by weight or less, and more preferably 7.5 parts by weight or less, based on 100 parts by weight of the total nylon.

[0116] (1-4) Layer structure of polyamide multilayer stretched film The polyamide-based multilayer stretched film of the present invention comprises a layer A containing a polyamide-based resin, a layer B containing a polyamide resin, and a layer C containing a polyamide resin. The film has at least a layer B containing 85 to 99% by weight of a polyester-based resin and 1 to 15% by weight of a polyester-based elastomer, and a layer C containing a barrier resin.

[0117] The embodiment of the polyamide-based multilayer stretched film of the present invention is preferably a laminate of layers A, B and C in this order. The multilayer stretched polyamide-based film of the present invention has a layer structure in which the A layer (PA Layer 1) / Layer B (PA layer 2) / Layer C (barrier layer) / Layer B (PA layer 2) / Layer A (PA layer 1), etc., stacked in 5 layers or more A layered structure is also possible.

[0118] The total thickness of the polyamide-based multilayer stretched film of the present invention is preferably about 10 to 50 μm. , and more preferably about 10 to 30 μm.

[0119] The thickness of the A layer (PA layer 1) is preferably about 0.5 to 30 μm, more preferably about 0.5 to 20 μm. The thickness of the A layer may be considered as the total thickness of the layers on both sides.

[0120] The thickness of the B layer (PA layer 2) is preferably about 0.5 to 30 μm, more preferably about 0.5 to 20 μm. The thickness of the B layer may be considered as the total thickness of the layers on both sides.

[0121] The thickness of the C layer (barrier layer) is preferably about 0.5 to 20 μm, more preferably about 0.5 to 15 μm. degrees.

[0122] In the case of five layers (A layer / B layer / C layer / B layer / A layer), the thickness of each layer is preferably about 0.5 to 29.5 μm for A layer (PA layer 1), about 0.5 to 29.5 μm for B layer (PA layer 2), and about 0.5 to 20 μm for C layer (barrier layer). The thickness of A layer is more preferably about 0.5 to 19.5 μm, and that of B layer is more preferably about 0.5 to 20 μm. The thickness of the layer C is preferably about 0.5 to 19.5 μm, and the thickness of the layer C is more preferably about 0.5 to 15 μm. The thickness of each of the layers A and B may be considered as the total thickness of the layers on both sides.

[0123] (2) Method for producing multilayer stretched polyamide film The method for producing the multilayer stretched polyamide-based film of the present invention is not particularly limited, and any conventionally known production method for forming a laminate can be preferably used.

[0124] To produce the multilayer stretched polyamide-based film of the present invention, the resin compositions for forming the A layer (PA layer 1), B layer (PA layer 2) and C layer (barrier layer) are co-extruded from a T-die onto a chill roll through which cooling water circulates, for example, in the order of A layer / B layer / C layer / B layer / A layer. This makes it possible to produce a flat multilayer stretched polyamide-based film.

[0125] The obtained multilayer stretched polyamide-based film may be uniaxially stretched or biaxially stretched (simultaneous biaxial stretching or sequential biaxial stretching). The stretching ratio is preferably about 2.5 to 4.5 times in the longitudinal direction (MD) and about 2.5 to 5.0 times in the transverse direction (TD).

[0126] In the case of sequential biaxial stretching, a polyamide multilayer stretched film is stretched longitudinally by 2.5 to 4.5 times using a roll stretching machine at 50 to 80 ° C., and then stretched laterally by 2.5 to 5.0 times using a tenter stretching machine in an atmosphere of 80 to 140 ° C. It is advisable to stretch the film and then heat treat it in an atmosphere of 180 to 220° C. using the same tenter.

[0127] The multilayer stretched polyamide-based film of the present invention may be uniaxially or biaxially stretched (simultaneous biaxial stretching or sequential biaxial stretching), and the obtained multilayer stretched polyamide-based film may be subjected to a corona discharge treatment on both surfaces or one surface, if necessary.

[0128] (3) Performance and applications of multi-layer oriented polyamide films Pinhole resistance due to bending The "pinhole resistance due to bending" is evaluated for a film using a Gelbo flex tester as described in the Examples below. In the case of the multilayer stretched polyamide-based film of the present invention, the number of pinholes generated in the pinhole resistance evaluation after bending 1000 times under the condition of 5°C is , preferably 5 or less.

[0129] Pinhole resistance due to wear The "resistance to pinholes due to wear" is evaluated by the method described in the Examples below. The number of sliding cycles until pinholes are formed is preferably 250 or more.

[0130] Haze Value The "haze value" is a value measured for a film according to JIS K7136 (2000) as described in the Examples below. The haze value is defined as the ratio (proportion) of the diffuse transmittance to the total light transmittance. In the multilayer stretched polyamide-based film of the present invention, the haze value (%) is preferably Most are 7% or less.

[0131] The multilayer stretched polyamide-based film of the present invention is suitable for packaging heavy items, particularly food items such as rice cakes and sausages, because it has excellent resistance to pinholes caused by bending and abrasion and has excellent transparency.

[0132] The multilayer stretched polyamide-based film of the present invention can also be suitably used for packaging frozen foods that are transported at low temperatures. EXAMPLES

[0133] The present invention will be described in more detail below with reference to examples and comparative examples.

[0134] The present invention is not limited to these examples.

[0135] (1) Raw materials used in the examples Table 1 shows the raw materials used in the examples and comparative examples.

[0136] [Table 1]

[0137] (2) Examples 1 and 2 and Comparative Examples 1 to 3 Using the raw materials shown in Table 1 above, resin compositions for forming layer A (PA layer 1), layer B (PA layer 2), and layer C (barrier layer) were prepared according to the formulations shown in Table 2.

[0138] The resin composition for forming the A layer further contained 900 ppm of silica having an average particle size of 3 μm as an antiblocking agent, and 300 ppm of ethylene bisstearic acid amide as a lubricant.

[0139] The resin compositions of the examples and comparative examples were each fed into an extruder at 250° C., and the layers were mixed to form a layer A / layer B / layer C / layer B. The layers were then layered in a feed block in the order A / B and extruded into a sheet from a T-die at 250°C onto a chill roll through which cooling water was circulating, producing a five-layer film with a layer structure of A / B / C / B / A.

[0140] The obtained film was then stretched longitudinally 3.0 times using a roll stretching machine at 65°C, and then stretched transversely 4.0 times using a tenter stretching machine in an atmosphere of 110°C.

[0141] Further, the film was heat-treated in an atmosphere of 210° C. using the same tenter to produce a 15 μm-thick, three-layer polyamide-based stretched film having a layer structure of A layer / B layer / A layer with the thickness ratio shown in Table 2.

[0142] The performance of the multilayer stretched polyamide-based films of the Examples and Comparative Examples was evaluated.

[0143] (3) Pinhole resistance due to bending of the film (Bending resistance test) The pinhole resistance of the multi-layer stretched polyamide film due to bending was measured using a Gelbo Flex Tester manufactured by Rikagaku Kogyo Co., Ltd.

[0144] A polyamide multilayer stretched film bag made into a cylindrical bag with a folded diameter of 150 mm and a length of 300 mm was attached to a Gelbo flex tester. A twist of 440° was applied to this bag over the first 88.9 cm. After 63.5 cm, the test was repeated at a speed of 40 times / s at 5°C. After repeating this for 1000 times at 1 min, the number of pinholes was counted using a penetrant.

[0145] The number of pinholes was measured at 300 cm 2 I did it at the place. Three sheets of The number of pinholes in each pull was counted, and the average value was used as the measurement result.

[0146] A sample film was deemed to have passed if the number of pinholes was 5 or less.

[0147] (4) Pinhole resistance due to film abrasion (abrasion resistance test) The film is attached to a pyramidal aluminum jig using tape, etc., and the top of the pyramidal jig is attached to a piece of cardboard (KOKUYO Campus Itameme Bipu size 430g / m2) via the film. 2 ) The radius of the apex is 0.1 to 1.0 mm in the sliding direction and 0.1 to 1.0 mm in the direction perpendicular to the sliding direction. A load of 63 g was placed on the jig. Under the condition of 65% humidity, the jig was moved at a speed of 2700 mm / min and a distance of 100 mm. The test piece was slid parallel to the cardboard at a distance of 45 mm, and the number of times it was slid was measured in increments of 50. The number of times it was slid was measured when a pinhole appeared. For example, if it opened after 300 times and did not open after 250 times, it was 300 times. The number of times was 100.

[0148] The occurrence of pinholes was judged by dropping a penetrating liquid on the film where the apex of the jig had been in contact and observing whether or not the liquid penetrated onto a piece of white paper.

[0149] For the sample film, 250 or more cycles was considered to be a pass.

[0150] FIG. 1 shows a schematic diagram of the measuring device, and FIG. 2 shows an example of a cone-shaped aluminum jig.

[0151] (5) Film haze value (transparency test) The haze value of the polyamide multilayer oriented film is measured according to JIS K7136 (2000). The measurement was performed using a haze meter (NDH-5000 manufactured by Nippon Denshoku Industries Co., Ltd.).

[0152] The haze value is defined as the ratio (proportion) of the diffuse transmittance to the total light transmittance, and can be calculated according to the following formula: Each sample was measured three times, and the average value was calculated.

[0153] Haze value (%) = (diffuse transmittance) / (total light transmittance) x 100 A sample film with a haze value of 7% or less was deemed to pass.

[0154] (6) Evaluation results of polyamide multilayer oriented film The results of the bending resistance test and the transparency test are shown in Table 2.

[0155] [Table 2]

[0156] The multilayer stretched polyamide-based film of the present invention is exemplified in Examples 1 and 2. Layer A is a polyamide. Contains polyamide resins (PA-1 and MXD6), and contains no more than 3% by weight of components other than polyamide resins. The layers contain 85 to 99% by weight of polyamide resins (PA-1 and PA-2) and 1 to 15% by weight of polyester elastomer (PEE), and the C layer contains a barrier resin (EVOH).

[0157] Due to these characteristics, the multilayer stretched polyamide-based film of the present invention has excellent pinhole resistance due to bending, pinhole resistance due to repeated contact, and transparency.

[0158] On the other hand, Comparative Examples 1 and 2 are the cases where the polyamide-based resin in the B layer is less than 85% by weight, and the polyamide-based resin in the B layer is more than 99% by weight. In other words, Comparative Examples 1 and 2 are the cases where the polyester-based elastomer in the B layer is less than 1% by weight, and the polyester-based elastomer in the B layer is 15% by weight. The films of Comparative Examples 1 and 2 have poor pinhole resistance and transparency due to bending. The clarity was not good.

[0159] In addition, the film of Comparative Example 3 contains 4% by weight of polyester elastomer (PEE) in the A layer. Therefore, the pinhole resistance due to repeated contact was insufficient.

Claims

1. A layer A contains a polyamide resin and contains 3% by weight or less of components other than the polyamide resin; A layer B including 94 to 98% by weight of a polyamide resin including nylon-6 / 6,6 and 2 to 6% by weight of a polyester elastomer; and The film has at least a layer C containing a barrier resin, The A layer, the B layer, and the C layer are laminated in this order, The haze value is 7% or less, The A layer comprises an aromatic polyamide, A multilayer stretched polyamide-based film, wherein the amount of aromatic polyamide in the layer A is 1 to 20% by weight, relative to the amount of polyamide resin in the layer A being 100% by weight.

2. 2. The polyamide-based multilayer stretched film according to claim 1, wherein the layer A contains an aliphatic polyamide.

3. 3. The polyamide-based multilayer stretched film according to claim 1, wherein the aromatic polyamide in the layer A is polymetaxylylene adipamide.

4. 3. The polyamide-based multilayer stretched film according to claim 1, wherein the barrier resin is an ethylene-vinyl alcohol copolymer or an aromatic polyamide.

Images