JP6694245B2 - Polyamide-based multilayer film - Google Patents

Description

  The present invention belongs to the technical field of polyamide-based multilayer films. TECHNICAL FIELD The present invention relates to a polyamide-based multilayer film including an ethylene-vinyl alcohol copolymer (hereinafter referred to as “EVOH”) resin layer having gas barrier properties and a polyamide-based resin layer. The present invention also relates to a bag for packaging foods and the like, which is manufactured from the polyamide-based multilayer film.

  Examples of materials having excellent gas (oxygen) barrier properties include aluminum foil, vinylidene chloride, and EVOH. Aluminum foil does not allow gas to pass through at all, but it is not transparent, so it cannot be used as a packaging material to show the contents. Since vinylidene chloride has a slight yellowish tint and contains chlorine, it is applied to a film as a coating material and partially used for food.

On the other hand, EVOH is a colorless and transparent thermoplastic resin that is melt-moldable and has excellent gas barrier properties and oil resistance. Such a polyamide-based multilayer film having EVOH as a gas barrier layer has excellent mechanical strength, pinhole resistance, and gas barrier properties, and is widely used as a film for packaging foods, medicines, and the like.
However, EVOH has a good gas barrier property under low humidity, but has a low gas barrier property under high humidity, and may be bleached when exposed to hot water. Therefore, when a polyamide-based multilayer film having an EVOH layer is used as a packaging material for foods that is subjected to high-temperature boil treatment or retort treatment, it is necessary to devise a method that does not cause a defective appearance due to whitening.

Many polyamide-based multilayer films that can be boiled or retorted have been reported (for example, Patent Documents 1 to 4).
Patent Document 1 discloses a multilayer package in which a composition comprising EVOH and a polyamide-based resin or a polyester-based resin is used as an intermediate layer, a highly moisture-permeable resin (eg, polyamide) is an outer layer, and a low moisture-permeable resin (eg, polypropylene) is an inner layer. (Multilayer film) is described and shown to improve the whitening of EVOH by retort treatment. Patent Document 2 describes a multilayer package (multilayer film) in which the intermediate layer described in Patent Document 1 is treated with a zirconium compound, thereby improving EVOH whitening due to retort treatment even when the content is water or oil. It shows that you do.

  Further, Patent Document 3 describes a polyamide-based multilayer film composed of a specific EVOH (specific saponified ethylene-vinyl acetate copolymer) layer and a specific polyamide layer, whereby the boil resistance and resistance of the film are improved. Improves retort performance. Patent Document 4 describes a polyamide-based multi-layer film in which both sides of an ethylene-vinyl acetate copolymer saponified layer are laminated with a plurality of polyamide layers, respectively, whereby the elongation of the film due to tension or heat during printing or lamination is reduced. However, the pinhole resistance due to bending and the pinhole resistance due to repeated contact are improved.

JP-A-1-253442 JP, 7-329254, A International Publication No. 2004/113071 JP, 2008-188774, A

  As described above, although many polyamide-based multilayer films having an EVOH layer have been reported, the problem that EVOH is whitened when subjected to high temperature boil treatment or retort treatment has not been sufficiently solved. In the polyamide-based multilayer film described in Patent Document 2, gel may be generated by the reaction between polyamide and EVOH, which may be unfavorable in appearance.

  An object of the present invention is mainly to provide a novel polyamide-based multilayer film suitable for producing a packaging film capable of preventing whitening of EVOH due to boil treatment at high temperature or retort treatment without impairing appearance and gas barrier property. To provide. Another object is to provide a packaging bag manufactured from such a polyamide-based multilayer film.

  As a result of intensive studies, the present inventors have found that the above problem can be solved by forming a multilayer film in which a certain additional resin layer is further added in addition to the EVOH resin layer and the polyamide resin layer, The present invention has been completed.

  Examples of the present invention include the following.

[1] If the sealant layer has an EVOH resin layer (A layer) and a polyamide resin layer (B layer) and is laminated with a sealant layer, at least the A layer is sandwiched between the sealant layers. An additional resin layer (C layer) mainly formed of at least one resin selected from the group consisting of polyester resin, polypropylene resin, polyethylene resin, cyclic olefin resin, and modified polyolefin resin on the surface opposite to And a C-layer is not laminated on the sealant layer, the C-layer is provided on both sides of the A-layer.
[2] The polyamide-based multilayer film according to the above [1], further having an adhesive resin layer (D layer).
[3] The polyamide-based multilayer film according to the above [1] or [2], wherein the thickness of the A layer is in the range of 0.5 to 12 μm.
[4] The polyamide-based multilayer film according to any one of the above [1] to [3], further having a sealant layer on a surface facing the C layer with the A layer interposed therebetween.

[5] A packaging bag, which is manufactured from the polyamide-based multilayer film according to any one of [1] to [4].

According to the present invention, it is possible to obtain a packaging film which is excellent in preventing EVOH whitening even under high temperature and high humidity, and therefore, to manufacture a packaging bag suitable for foods which are subjected particularly to boil treatment or retort treatment at high temperature. be able to.

Hereinafter, the present invention will be described in detail.
1 Regarding the Film of the Present Invention The polyamide-based multilayer film of the present invention (hereinafter referred to as the “film of the present invention”) has an EVOH resin layer (A layer) and a polyamide-based resin layer (B layer), and in addition, a sealant layer. In the case of being laminated, a polyester resin, a polypropylene resin, a polyethylene resin, a cyclic olefin resin, and a modified polyolefin resin are provided on at least the surface facing the sealant layer with the A layer sandwiched therebetween. In the case where an additional resin layer (C layer) mainly composed of at least one resin selected from the group consisting of resins is used and a sealant layer is not laminated, the C layer is sandwiched on both sides of the A layer. It is characterized by having a layer.

  Here, "mainly" means being substantially composed of only the resin, but excludes the inclusion of other resins, additives, etc. within a range not impairing the effects of the present invention. is not. The film of the present invention may or may not include a sealant layer.

1.1 EVOH resin layer (A layer)
The EVOH resin layer (A layer) is a resin layer mainly composed of EVOH. The EVOH resin layer can be said to be an intermediate layer of the film of the present invention, and usually has only one layer, but it does not prevent having a plurality of layers.

  EVOH is usually a saponified ethylene-vinyl ester copolymer. The ethylene content of EVOH is appropriately 60 mol% or less, preferably in the range of 20 to 55 mol%, more preferably in the range of 25 to 45 mol%. If the ethylene content is too low, the water resistance, hot water resistance, and moisture resistance will decrease, as well as the gas barrier properties under high humidity will be impaired, stress cracking resistance will decrease, and it will be difficult to maintain good melt processing characteristics. .. On the other hand, when it is more than 60 mol%, water resistance, hot water resistance and moisture resistance are improved, but the originally excellent gas barrier property may be deteriorated. The degree of saponification of the vinyl ester component is usually 90 mol% or more, preferably 95 mol% or more, and more preferably 98 mol%. If the degree of saponification is less than 90 mol%, the thermal stability will be poor and gel will be likely to be generated during melt processing. In addition, gas barrier properties and oil resistance are also lowered, and there is a possibility that the original characteristics of EVOH may not be maintained.

  The “vinyl ester” relating to EVOH is not particularly limited, but examples thereof include lower or higher fatty acid vinyl ester (vinyl acetate, vinyl propionate, vinyl pipariate, etc.) and vinyl aromatic carboxylate. Of these, vinyl acetate is particularly preferable. Thus, the preferred EVOH is a saponified ethylene-vinyl acetate copolymer. The vinyl ester may be used alone or in combination of two or more.

  In addition, EVOH contains an α-olefin such as propylene, isobutene, α-octene, α-dodecene, α-octadecene, etc., an unsaturated carboxylic acid or a salt or partial alkyl thereof in a range that does not impair the effects of the present invention. It may contain a comonomer such as ester, completely alkyl ester, nitrile, amide, anhydride, unsaturated sulfonic acid or a salt thereof.

  Further, when measured according to Japanese Industrial Standard (JIS) K-7210 (condition: 210 ° C., 21.18 N load), the melt flow rate (MFR) value is within a range of 0.5 to 20 g / 10 minutes. Certain EVOHs are preferred, and EVOHs within the range of 1-12 g / 10 min are more preferred. If the MFR is less than 0.5 g / 10 min, melt extrusion may be hindered, and conversely, if it is more than 20 g / 10 min, the film formability may be deteriorated.

  EVOH is commercially available and can be used in the present invention. Examples of such commercially available products include Soarnol (registered trademark) (DC3203, DT2904, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) and EVAL (registered trademark) (F171B, manufactured by Kuraray Co., Ltd.).

1.2 Polyamide resin layer (B layer)
The polyamide resin layer (B layer) is a resin layer mainly made of polyamide resin. Examples of the polyamide-based resin include aliphatic polyamide, aromatic polyamide, amorphous polyamide, and polyamide elastomer. The polyamide-based resin layer (B layer) according to the present invention is usually an aliphatic polyamide. Is an essential component, and if necessary, aromatic polyamide, amorphous polyamide, polyamide elastomer, etc. may be contained.

  One or a plurality of polyamide-based resin layers can be present on one surface side or both surface sides of the EVOH resin layer as the intermediate layer. Further, the polyamide resin layer and the EVOH resin layer may be adjacent to each other, and an additional resin layer (C layer) or an adhesive resin layer (D layer) described later may be provided between the polyamide resin layer and the EVOH resin layer. You may have.

  Examples of the aliphatic polyamide include aliphatic nylon and copolymers thereof. Specifically, for example, polycapramide (nylon-6), poly-ω-aminoheptanoic acid (nylon-7), poly-ω-aminononanoic acid (nylon-9), polyundecane amide (nylon-11), polylauryl Lactam (nylon-12), polyethylenediamineadipamide (nylon-2,6), polytetramethyleneadipamide (nylon-4,6), polyhexamethyleneadipamide (nylon-6,6), polyhexa Methylene sebacamide (nylon-6,10), polyhexamethylene dodecamide (nylon-6,12), polyoctamethylene adipamide (nylon-8,6), polydecamethylene adipamide (nylon-10, 8), caprolactam / lauryllactam copolymer (nylon-6 / 12), caprolactam / ω-aminonona Acid copolymer (nylon-6 / 9), caprolactam / hexamethylene diammonium adipate copolymer (nylon-6 / 6,6), lauryl lactam / hexamethylene diammonium adipate copolymer (nylon-12 / 6,6) 6), ethylenediamine adipamide / hexamethylene diammonium adipate copolymer (nylon-2,6 / 6,6), caprolactam / hexamethylene diammonium adipate / hexamethylene diammonium sebacate copolymer (nylon-6, 6 / 6,10), ethylene ammonium adipate / hexamethylene diammonium adipate / hexamethylene diammonium sebacate copolymer (nylon-6 / 6,6 / 6,10), 6T-6I nylon, MXD-6 nylon. Can be mentioned. These may be used alone or in combination of two or more.

  As the aromatic polyamide, for example, a xylylenediamine-based polyamide, specifically, a polymer synthesized from meta and / or para-xylylenediamine and a dicarboxylic acid such as adipic acid can be mentioned.

Examples of the amorphous polyamide include isophthalic acid-terephthalic acid-hexamethylenediamine polycondensate.
Examples of polyamide elastomers include polyether ester amides.

  In addition, in the polyamide-based resin, the relative viscosity when measured according to Japanese Industrial Standard (JIS) K-6920 (2009) (conditions: 96% by mass sulfuric acid, 25 ° C.) is from 2.0 to A polyamide resin within the range of 4.2 is preferable, and a polyamide resin within the range of 2.6 to 4.0 is more preferable. If the relative viscosity is less than 2.0, the film formability may be deteriorated, and if it is greater than 4.2, melt extrusion may be hindered.

  The content of the aliphatic polyamide in the polyamide resin layer is usually in the range of about 30 to 99% by mass, preferably in the range of about 50 to 99% by mass, more preferably in the range of about 80 to 96% by mass. Within.

  The content of the aromatic polyamide, the amorphous polyamide, the polyamide elastomer, etc. in the polyamide resin layer is usually in the range of about 0 to 40% by mass, preferably about 2 to 30% by mass. It is within the range.

1.3 Additional resin layer (C layer)
The additional resin layer (C layer) is a resin layer mainly composed of at least one resin selected from the group consisting of polyester resins, polypropylene resins, polyethylene resins, cyclic olefin resins, and modified polyolefin resins. These may be a single resin layer or a mixed resin layer.

  One or a plurality of additional resin layers may be present on one surface side or both surface sides of the EVOH resin layer as the intermediate layer. Further, the additional resin layer and the EVOH resin layer may be adjacent to each other, and between the additional resin layer and the EVOH resin layer, the polyamide resin layer (B layer) or an adhesive resin layer (D layer) described later. May have.

1.3.1 Polyester Resin Examples of the polyester resin according to the present invention include polyethylene terephthalate (PET), polyethylene terephthalate / isophthalate, polybutylene terephthalate (PBT), and polyethylene naphthalate. These may be used alone or in combination of two or more. If necessary, other resin compatible with the polyester resin may be contained, but the polyester resin is preferably 50% by mass or more with respect to the mass of the C layer.

  As a preferable polyester-based resin, polyester having a melting point of 200 ° C. or higher can be mentioned, but from the viewpoint of heat resistance, polyethylene terephthalate (PET) is more preferable.

  In addition, among the polyester resins, the intrinsic viscosity (IV value) when measured according to Japanese Industrial Standard (JIS) K-7367-5 (condition: 25 ° C.) is 0.5 to 1.4 dl / A polyester resin in the range of g is preferable, and a polyester resin in the range of 0.6 to 1.0 is more preferable. If the intrinsic viscosity is less than 0.5 dl / g, the film-forming property may be deteriorated, and if it is greater than 1.4 dl / g, melt extrusion may be hindered.

1.3.2 Polypropylene Resin The polypropylene resin according to the present invention is a homopolymer of propylene or a copolymer of propylene and other α-olefin. Examples of the α-olefin other than propylene include α-olefins other than propylene having 2 to 20 carbon atoms, and specific examples thereof include ethylene, 1-butene, 1-pentene, and 1-hexene. , 4-methyl-1-pentene, 3-methyl-1-pentene, 1-octene, 3-methyl-1-butene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1 -Eicosene, cyclopentene, cycloheptene, norbornene, 5-ethyl-2-norbornene, tetracyclododecene, 2-ethyl-1,4,5,8-dimethano-1,2,3,4,4a, 5,8, 8a-octahydronaphthalene. Among them, those having 2 to 4 carbon atoms, such as ethylene and butene, are preferable, and ethylene is more preferable. These α-olefins other than propylene may be used alone or in combination of two or more.

  The content ratio of the α-olefin other than propylene in the propylene-based copolymer is appropriately in the range of 0.5 to 15 mol%, preferably in the range of 1 to 12 mol%, and preferably 3 to 10 mol%. The range of is more preferable.

  The propylene-based copolymer is not particularly limited as long as it is a copolymer of propylene and other α-olefin, and specifically, for example, propylene-ethylene random copolymer, propylene-butene random copolymer. Examples thereof include polymers and propylene-ethylene-butene random copolymers. Among these, a propylene-ethylene random copolymer and a propylene-ethylene-butene random copolymer are preferable, and a propylene-ethylene random copolymer is more preferable. Also, a mixture of these may be used.

  Among the polypropylene resins, the melt flow rate (MFR) value when measured according to Japanese Industrial Standard (JIS) K-7210 (1990) (condition: 230 ° C., 21.18 N load) is 0.5 to A polypropylene resin in the range of 50 g / 10 minutes is preferable, and a polypropylene resin in the range of 1 to 20 g / 10 minutes is more preferable. If the MFR is less than 0.5 g / 10 min, melt extrusion may be hindered, and conversely, if it is more than 50 g / 10 min, the film formability may be deteriorated.

Further, among the polypropylene-based resins, a polypropylene-based resin having a density in the range of 850 to 950 kg / m ³ when measured according to Japanese Industrial Standard (JIS) K-7112 (1999) is preferable, and 860 More preferably, the polypropylene resin is in the range of up to 920 kg / m ³ .

1.3.3 Polyethylene-based resin The polyethylene-based resin according to the present invention is an ethylene homopolymer or a copolymer containing ethylene as a main component. Specific examples include branched low-density polyethylene, linear low-density polyethylene, and high-density polyethylene.

  Examples of the linear low-density polyethylene include ethylene as a main component, and examples thereof include copolymers with α-olefins such as butene, pentene, hexene, heptene, and octene.

  Other polyethylene resins include copolymers or multi-polymers of ethylene and (meth) acrylic acid, itaconic acid, maleic anhydride, vinyl acetate, vinyl propionate, etc., which are random copolymers. Alternatively, it may be a block copolymer.

  Among the polyethylene resins, the melt flow rate (MFR) value when measured according to Japanese Industrial Standard (JIS) K-7210 (condition: 190 ° C., 21.18 N load) is 0.5 to 20 g / A polyethylene resin in the range of 10 minutes is preferable, and a polypropylene resin in the range of 1 to 10 g / 10 minutes is more preferable. If the MFR is less than 0.5 g / 10 min, melt extrusion may be hindered, and conversely, if it is more than 20 g / 10 min, the film formability may be deteriorated.

Further, among the polyethylene-based resins, a polypropylene-based resin having a density in the range of 900 to 940 kg / m ³ when measured according to Japanese Industrial Standard (JIS) K-7112 is preferable, and 905 to 935 kg / A polyethylene resin having a range of m ³ is more preferable.

1.3.4 Cyclic Olefin Resin As the cyclic olefin resin according to the present invention, specifically, (a) ethylene or propylene and a cyclic olefin (for example, norbornene and its derivative, tetracyclododecene and its derivative, etc.) A random copolymer of (b) a ring-opening polymer of the cyclic olefin or a copolymer thereof, (c) a hydrogenated polymer of the polymer of (b) above, (d) an unsaturated carboxylic acid and its The graft modified products of the above (a) to (c) with a derivative or the like can be mentioned.

  Among the cyclic olefin resins, the melt flow rate (MFR) value when measured in accordance with American Society for Testing and Materials Standards (ASTM) D1238 (conditions: 260 ° C., 21.18 N load) is 4 to 50 g / 10. The cyclic olefin-based resin in the range of 6 to 38 g / 10 minutes is more preferable, and the cyclic olefin-based resin in the range of 6 to 38 g / 10 minutes is more preferable. If the MFR is less than 4 g / 10 min, melt extrusion may be hindered, and if it is more than 50 g / 10 min, the film-forming property may be deteriorated.

Further, among the cyclic olefin-based resins, a cyclic olefin-based resin having a density of 970 to 1100 kg / m ³ when measured according to American Society for Testing and Materials (ASTM) D792 is preferable, and 980 to 980 is preferable. Cyclic olefin-based resins having a weight ratio of 1050 kg / m ³ are more preferable.

1.3.5 Modified polyolefin-based resin The modified olefin-based resin according to the present invention is a polyolefin-based resin in which unsaturated carboxylic acid, its anhydride or derivative is graft-copolymerized. Examples of polyolefins include polypropylene and polyethylene.

  The unsaturated carboxylic acid, its anhydride or their derivatives is a compound having an ethylenically unsaturated bond and a carboxyl group, an acid anhydride group or a derivative group in one molecule. Specific examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, α-ethylacrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, endocis -Unsaturated carboxylic acids such as bicyclo [2.2.1] hept-2,3-dicarboxylic acid and methyl-endocis-bicyclo [2.2.1] hept-5-ene-2,3-dicarboxylic acid; Unsaturated carboxylic acid anhydrides; unsaturated carboxylic acid halides, unsaturated carboxylic acid amides, and unsaturated carboxylic acid imide derivatives. More specific examples include maleenyl chloride, maleimide, N-phenylmaleimide, maleic anhydride, itaconic anhydride, citraconic anhydride, monomethyl maleate, dimethyl maleate and glycidyl maleate. Among these, acrylic acid, methacrylic acid, maleic acid, nadic acid, maleic anhydride, itaconic anhydride and nadic acid anhydride are preferable, and maleic anhydride is more preferable. Such unsaturated carboxylic acids and their derivatives may be used alone or in combination of two or more.

  Among the modified polyolefin resins, the melt flow rate (MFR) value when measured according to American Society for Testing and Materials Standards (ASTM) D792 (condition: 190 ° C., 21.18 N load) is 0.5 to 20 g. The modified polyolefin-based resin is preferably within the range of / 10 minutes, more preferably the modified polyolefin-based resin is within the range of 1 to 10 g / 10 minutes. If the MFR is less than 0.5 g / 10 min, melt extrusion may be hindered, and conversely, if it is more than 20 g / 10 min, the film formability may be deteriorated.

Further, the inside of the modified polyolefin resin, density when measured in accordance with ASTM D1505 is preferably modified polyolefin resin is in the range of 870~940kg / ^{m 3,} within the scope of 880~935kg / ^{m 3} The modified polyolefin resin is

1.4 Other resin layers The film of the present invention may have other polymer resin layers, for example, an adhesive resin layer (D layer), if necessary, in addition to the A layer to the C layer.

  The adhesive resin layer (D layer) can be provided to improve the adhesion between the layers. Examples of the resin that can be used for the adhesive resin layer (D layer) include a modified polyolefin resin, a modified polyester elastomer, and a modified styrene elastomer.

1.4.1 Modified polyolefin resin The same resins as those mentioned in the above section "1.3.5" can be mentioned.

1.4.2 Modified polyester-based elastomer The modified polyester-based elastomer according to the present invention is a saturated polyester-based thermoplastic elastomer containing a polyalkylene ether glycol segment modified with an unsaturated carboxylic acid or a derivative thereof. Specifically, it is obtained by modifying a saturated polyester thermoplastic elastomer having a polyalkylene ether glycol segment content of 58 to 73% by mass with an unsaturated carboxylic acid or a derivative thereof in the presence of a radical generator. It is a modified polyester elastomer. Since the reactive group is introduced by the grafting reaction and terminal addition reaction of the unsaturated carboxylic acid or its derivative, the chemical bondability and hydrogen bondability with various resins are improved.

  The saturated polyester thermoplastic elastomer is a block copolymer composed 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 is the polyester series. It is within the range of about 58 to 73 mass% in the elastomer.

  Examples of the polyalkylene ether glycol forming the soft segment include polyethylene glycol, poly (1,2 and 1,3-propylene ether) glycol, poly (tetramethylene ether) glycol, and poly (hexamethylene ether) glycol. You can The number average molecular weight of the polyalkylene ether glycol is usually in the range of 400 to 6000.

  Examples of the unsaturated carboxylic acid or its derivative include unsaturated carboxylic acids such as acrylic acid, maleic acid and fumaric acid, their acid anhydrides, their esters and their metal salts.

1.4.3 Modified styrene-based elastomer The modified styrene-based elastomer according to the present invention is a carboxyl group-containing styrene-based elastomer, and includes a styrene-butadiene block copolymer, a styrene-isoprene-styrene block copolymer, and a styrene-ethylene propylene. At least one styrene elastomer selected from the group consisting of block copolymers, styrene-ethylene propylene-styrene block copolymers, styrene-butadiene-styrene block copolymers, styrene-ethylene butylene-styrene block copolymers , Unsaturated carboxylic acid or unsaturated carboxylic acid anhydride. Specific examples thereof include Tuftec M series manufactured by Asahi Kasei Corporation and Clayton FG series manufactured by Kraton Polymers.

1.5 Others 1.5.1 Thickness of the Film of the Present Invention The total thickness of the film of the present invention is usually in the range of about 9 to 50 μm and about 12 to 40 μm, although it depends on the constitution of each layer and the components of each layer. The range of is preferable.

  Regarding the thickness of each layer, the thickness of the EVOH resin layer (A layer) is usually within a range of about 0.5 to 12 μm, preferably within a range of about 1 to 10 μm, and within a range of about 1.5 to 6 μm. Is more preferable. The thickness of the polyamide resin layer (B layer) is usually in the range of about 3 to 35 μm, preferably about 5 to 25 μm. The thickness of the C layer is at least 1 μm, preferably in the range of about 1 to 10 μm, and more preferably in the range of about 1 to 6 μm. The thickness of the adhesive resin layer (D layer) is usually in the range of about 0.5 to 5 μm, preferably in the range of about 1 to 3 μm.

1.5.2 Laminated Structure of the Film of the Present Invention The film of the present invention can have the following laminated structure, for example.
C layer / (D layer /) A layer / B layer C layer / (D layer /) B layer / A layer / B layer / (D layer /) C layer C layer / (D layer /) B layer / A layer / B layer / B layer / C layer / (D layer /) A layer / B layer / B layer / C layer / (D layer /) A layer / C layer / (D layer /) B layer / B Layer / C layer / (D layer /) B layer / A layer / B layer / C layer / (D layer /) B layer / A layer / B layer

  It is preferable to provide an adhesive resin layer (D layer) between the C layer and other layers, if necessary. When the C layer is mainly composed of the modified polyolefin resin, it is not always necessary to provide the adhesive resin layer (D layer).

1.5.3 Additives In the film of the present invention, various additives can be blended in appropriate amounts within a range that does not impair the effects of the present invention. As such additives, it is possible to add antioxidants, lubricants, ultraviolet absorbers, flame retardants, colorants, antiblocking agents, antistatic agents, fillers, antibacterial agents and the like. Specific examples of some additives are as follows.

  Examples of the antioxidants include phenolic antioxidants, phosphorus antioxidants, thioether antioxidants and the like. Examples of the phenolic antioxidant include 3,9-bis [2- {3- (3-t-butyl 4-hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethylethyl] -2, 4,8,10-Tetraoxaspiro [5,5] undecane, 6- [3- (3-t-butyl 4-hydroxy-5-methylphenyl) propoxy] -2,4,8,10-tetra-t -Butylbenz [d, f] [1,3,2] dioxaphosphepine, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,5 -Di-t-butylhydroquinone, 2,6-di-t-butyl-p-cresol, 4,4-thiobis (6-t-butylphenol), 2,2'-methylene-bis- (4-methyl-6) -T-bu Le phenol), octadecyl-3- (3 ', 5'-di -t- butyl-4'-hydroxyphenyl) propionate, 4,4'-thiobis - (6-t-butylphenol) and the like. Examples of phosphorus-based antioxidants include tris (2,4-di-t-butylphenyl) phosphite, di (2,4-di-t-butylphenyl) -pentaerythritol-diphosphite, 9,10-dihydro-9. Mention may be made of -oxa-10-phosphaphenanthrene. Examples of thioether-based antioxidants include dilauryl-3,3'-thio-di-propinate.

  Examples of the colorant include carbon black, phthalocyanine, quinacridone, indoline, azo pigments, titanium oxide, and red iron oxide.

  Examples of the antistatic agent include pentaerythritol monostearate, sorbin monopalmitate, sulfated oleic acid, polyethylene oxide, and carbon wax.

  As the filler, for example, glass fiber, asbestos, mica, sericite, talc, glass flakes, ballastonite, calcium silicate, aluminum silicate, montmorillonite, hectorite, beidellite, nontronite, saponite, sauconite, stevensite. Can be mentioned.

  Further, a metal (alkali metal, alkaline earth metal, transition metal, etc.) salt may be contained, and further, boron, silica or the like may be contained.

1.6 Method for Manufacturing Film of the Present Invention The film of the present invention can be manufactured by a known method without particular limitation. Specifically, for example, the resin forming each layer is coextruded from a T-die onto a chill roll in which cooling water circulates in a desired order to obtain a flat multilayer film. The obtained film is, for example, longitudinally stretched 2 to 4 times by a roll stretching machine at 50 to 100 ° C., and further laterally stretched 2 to 5 times by a tenter stretching machine in an atmosphere at 90 to 150 ° C., and subsequently the same tenter. Thus, the film of the present invention can be obtained by heat treatment in an atmosphere of 100 to 240 ° C. The film of the present invention may be uniaxially stretched or biaxially stretched (simultaneous biaxially stretched, sequential biaxially stretched), and the obtained multilayer film may be subjected to corona discharge treatment on both surfaces or one surface thereof if necessary. it can.

2 Regarding the Packaging Bag of the Present Invention Next, the packaging bag manufactured from the film of the present invention (hereinafter referred to as "the packaging bag of the present invention") will be described in detail. The film of the present invention can be suitably used for producing a packaging film.

  When manufacturing the packaging bag of the present invention for foods, it is preferable to laminate a sealant layer on the surface of the film of the present invention facing the C layer with the A layer (intermediate layer) interposed therebetween by a conventional method. Using the film (packaging film) on which this sealant layer is laminated, the sealant layer is treated so as to be the innermost layer, and then the sealant layer surfaces are heat-sealed to form a bag-like product for the present invention packaging. Bags can be manufactured. Specifically, the packaging film produced from the film of the present invention can be used to produce the packaging bag of the present invention by molding with an automatic packaging machine or the like. Examples of such an automatic packaging machine include a vertical pillow packaging machine, a horizontal pillow packaging machine, and other packaging machines and bag-making machines.

  The sealant layer can be produced from a resin having a heat-sealing property, and examples of such a resin include low density, medium density, high density, linear low density polyethylene; propylene homopolymer, Examples thereof include polypropylene such as propylene copolymer such as propylene-ethylene copolymer; polyvinyl acetate resin.

  As a method for applying the sealant layer to the polyamide-based multilayer film, a known method can be used. Further, a known method can be adopted as the method of heat sealing. The thickness of the sealant layer is usually 20 μm or more, preferably in the range of about 25 to 100 μm, and more preferably in the range of about 30 to 80 μm.

  The contents that can be packaged in the packaging bag of the present invention are not particularly limited, and examples thereof include water-based foods such as soup, konjac, pickles, and foods such as rice cakes, wieners, seasonings, shampoos, rinses, and body soaps. , Daily products such as detergents, pharmaceuticals, pesticides, and organic chemicals. Among them, the packaging bag of the present invention is useful for foods such as boiled foods and retort foods that are sterilized at high temperature and high humidity.

Examples of the form of the packaging bag of the present invention include bag-like forms such as three-way seal type, envelope type, casette type, flat bottom type, spout pouch, and refilling pouch.

  Hereinafter, the present invention will be described with reference to examples and the like, but the present invention is not limited to these examples.

The main raw materials are as follows.
-Polyester: polyethylene terephthalate (intrinsic viscosity 0.71 dl / g)
EVOH: saponified ethylene-vinyl acetate copolymer (DC3203, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.)
・ Nylon: Nylon 6 (Relative viscosity in 96% by mass sulfuric acid is 3.5)
-Adhesion 1: Modified polyester elastomer (Primalloy IF203, manufactured by Mitsubishi Chemical Corporation)
Adhesion 2: Maleic anhydride modified polyolefin resin (Admer QF580, manufactured by Mitsui Chemicals, Inc.)
Modified PO: Maleic anhydride modified polyolefin resin (Admer NF556, manufactured by Mitsui Chemicals, Inc.)
PP: Propylene homopolymer (specific gravity 900 kg / m ³ , MFR = 3 g / 10 minutes)
・ PE: Linear low-density polyethylene (specific gravity 925 kg / m ³ , MFR = 2 g / 10 min)
-Cyclic PO: cyclic olefin copolymer (specific gravity 1010 kg / m ³ , MFR = 32 g / 10 min)
CPP40: unstretched polypropylene film (pyrene film CT-P1128, thickness 40 μm, manufactured by Toyobo Co., Ltd.)

[Example 1]
Each of the polyester resin (C layer), EVOH resin (A layer), nylon resin (B layer), and adhesive resin (D layer) constituting each layer is melt-extruded to obtain C layer / D layer / A layer / B layer. Co-extrusion was carried out on a chill roll in which cooling water circulated through a T-die in order to obtain a flat four-layer film. Next, this 4-layer film was longitudinally stretched 2.7 times by a roll stretching machine at 65 ° C., then laterally stretched 4 times by a tenter stretching machine in an atmosphere at 110 ° C., and further in the atmosphere at 210 ° C. by the same tenter. Heat treatment was performed to obtain a four-layer stretched film (film of the present invention) having a thickness of 15 μm.

A laminated packaging material (packaging film) was obtained by laminating CPP40 (sealant layer) on the obtained 4-layer stretched film on the layer B side by dry lamination (dry coating amount 4.0 g / m ² ). As an adhesive for dry lamination, A-626 (manufactured by Mitsui Chemicals, Inc.) / A-50 (manufactured by Mitsui Chemicals, Inc.) (weight mixing ratio 8/1) was used.

[Examples 2 to 11, Comparative Example 1, Comparative Example 2]
In the same manner as in Example 1, a laminated packaging material (packaging film) having each laminated structure according to Examples 2 to 11 shown in Table 1, Comparative Example 1 and Comparative Example 2 was obtained.

[Test Example 1] Evaluation of boil whitening (measurement of haze value)
After aging each laminated wrapping material at 40 ° C. for 48 hours, a bag of 8 cm × 10 cm was made using each laminated wrapping material, and 50 mL of water was put into the bag for evaluation. This sample was evaluated for whitening based on the change in haze value before and after boiling treatment for 60 minutes with boiling water. Regarding the haze measurement after the boil treatment, the haze was measured after drying overnight at room temperature.

  The haze value was measured using a haze meter NDH-5000 manufactured by Nippon Denshoku Industries Co., Ltd. according to Japanese Industrial Standard (JIS) K-7136 (2000). The results are shown in Table 2.

  From the results in Table 2, it is clear that the haze value of the laminated packaging materials produced from the films of the present invention according to Examples 1 to 11 is extremely low at 0.5% or less, and whitening during boil treatment is suppressed. .. On the other hand, the haze value of the laminate packaging materials according to Comparative Examples 1 and 2 was as high as 15% or more, and whitening occurred due to boil treatment.

Since a packaging film excellent in preventing EVOH whitening even under high temperature and high humidity can be obtained from the film of the present invention, the film of the present invention can be used as a packaging bag suitable for foods which are subjected to boil treatment or retort treatment at a high temperature. Useful for manufacturing.

Claims (3)

An ethylene-vinyl alcohol copolymer resin layer (A layer), a polyamide resin layer (B layer), and an adhesive resin layer (D layer) mainly composed of a modified polyester elastomer, and in addition, an unstretched polypropylene film Is laminated as an innermost layer, and an additional resin layer (C layer) mainly made of polyester resin is provided on the surface of the side facing the sealant layer with the A layer interposed therebetween. A polyamide-based multilayer film for packaging (excluding those having a cyclic polyolefin resin layer). The polyamide multilayer film for packaging according to claim 1, wherein the thickness of the A layer is in the range of 0.5 to 12 μm. A bag for packaging, which is manufactured from the polyamide-based multilayer film for packaging according to claim 1 or 2.