JP2008213840A - Oxygen-absorbing packaging material and package - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an excellent oxygen-absorbing packaging material and a package which has a capacity of absorbing oxygen in the packaging material, and is capable of maintaining the quality of a food putting a high priority on the flavor or a pet food for animals having sensible taste because any odor material or the like is not shifted to a content. <P>SOLUTION: The packaging material has at least an oxygen absorbing resin composition layer, and the oxygen absorption rate of the oxygen absorbing resin composition layer at 23°C and 50%RH is ≥2.0 cc/(m<SP>2</SP>day). The oxygen absorbing resin composition of the packaging material has the composition consisting of EVOH, a thermoplastic resin having a carbon-carbon double bond substantially only in a main chain, and a transition metal salt. The package packed food and pet food with the packaging material. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an oxygen-absorbing packaging material and a package packaged with the packaging material.

  As materials for packaging materials such as foods, pharmaceuticals, and pet foods, materials that block oxygen, such as glass and metal, have been used in the past because of the reason that the packaged items may lose their flavor due to oxygen. Furthermore, recently, plastic containers having a gas barrier property have come to be used for the reasons that there are few concerns about breakage and deformation during transportation and the appearance is good.

  Furthermore, among these items to be packaged, those that are sensitive to oxygen and in which mixing of oxygen is difficult to avoid at the time of packaging often take a method of enclosing an oxygen absorbent in the packaging material. However, especially when packaging foods and pharmaceuticals, there is a concern that such an oxygen absorbent is swallowed by mistake.

  On the other hand, providing oxygen absorption property to packaging material itself has also been performed. For example, Patent Document 1 discloses a composition having an oxygen-absorbing ability containing a polymer containing a carbon-carbon double bond and a transition metal salt. It is described that oxygen can be absorbed.

  It is also known to impart an oxygen scavenging function to the gas barrier layer. For example, Patent Document 2 discloses a resin composition containing a resin having a carbon-carbon double bond substantially only in the main chain, a transition metal salt, and an ethylene-vinyl alcohol copolymer, and has a high gas barrier. It is described that the property can be obtained, and that this is used as a multilayer body for a container or the like.

  On the other hand, Patent Document 3 describes a multilayer body including an EVOH layer containing an oxidizable polydiene and a metal salt catalyst and a polyamide layer. Patent Document 3 discloses a multilayer structure in which a resin composition layer containing EVOH, a functionalized polybutadiene, and a cobalt salt is used as an inner core layer, and even if the multilayer structure is retorted, it is zero over several days. It is described that a close oxygen permeability coefficient (hereinafter, oxygen permeability coefficient may be abbreviated as OTR) can be maintained.

JP-A-8-502306 JP 2006-335809 A JP-T-2004-527395 JP 2002-146217 A International Publication No. WO03 / 072653

  However, as in Patent Documents 1 and 3, when the oxygen scavenging function is imparted to a resin having poor gas barrier properties, the oxygen absorption rate is easy to obtain, but as the oxygen is absorbed, the thermoplastic resin is oxidized. Oxidized molecular fragments are generated and transferred to foods, thereby generating odors that are problematic in applications where the flavor is particularly important.

  Moreover, in the resin composition disclosed in Patent Document 2, the generation of odor is suppressed, but the purpose of Patent Document 2 is a high degree of oxygen blocking, and oxygen mixed in the packaging material in food packaging or the like is used. In terms of absorption, the oxygen absorption rate may not be practically sufficient.

  Accordingly, an object of the present invention is to provide a packaging material that has a practically sufficient oxygen absorption capacity and does not impair the flavor of the contents.

  By adopting a packaging material having an ethylene-vinyl alcohol copolymer composition layer having an oxygen absorption capacity of a certain level or more, the present inventors can prevent the flavor of the contents from being impaired in practice, and further specify By adopting a resin composition layer containing a specific composition of an ethylene-vinyl alcohol copolymer, a resin having a carbon-carbon double bond substantially only in the main chain, and a transition metal salt, the oxygen The present inventors have found that absorption capacity and low odor can be realized at the same time, and have reached the present invention.

That is, the present invention comprises an oxygen-absorbing resin composition (P) comprising an ethylene-vinyl alcohol copolymer (B) and a resin (A1) containing a carbon-carbon double bond substantially only in the main chain. A packaging material including an oxygen absorption layer, wherein the oxygen absorption rate of the oxygen absorption layer at 23 ° C. and 50% RH is 2.0 cc / (m ² · day) or more.

  The packaging material of the present invention has a practically sufficient oxygen absorption capacity and can be preserved without losing the flavor of the content even when the content that emphasizes the flavor is packaged under normal air. .

Hereinafter, embodiments of the present invention will be described. The present invention relates to oxygen absorption comprising an oxygen-absorbing resin composition (P) comprising an ethylene-vinyl alcohol copolymer (B) and a resin (A1) containing a carbon-carbon double bond substantially only in the main chain. A packaging material including a layer, wherein the oxygen absorption rate of the oxygen absorption layer at 23 ° C. and 50% RH is 2.0 cc / (m ² · day) or more.

In the packaging material of this invention, it has an oxygen absorption layer whose oxygen absorption rate in 23 degreeC and 50% RH (relative humidity) of this oxygen absorption layer is 2.0 cc / (m < ² > * day) or more. By having such an oxygen absorption rate, when normal food or pet food is filled in the packaging material under air at normal room temperature conditions, the oxygen inside the packaging material is changed to the flavor of the package. Can be absorbed before oxygen degradation. The oxygen absorption rate is an oxygen absorption rate measured by the method described in the examples described later.

The oxygen absorption rate, packaging it is better of course greater from the viewpoint of absorbing oxygen within, preferably 4.0cc ^/ (m 2 · day) or more, more preferably 10cc ^/ (m 2 · day) or more is there. However, if the oxygen absorption rate is increased too much, it is necessary to increase the oxygen penetration rate into the oxygen absorption layer. At the same time, the low molecular weight component of the oxygen absorption layer and the oxygen absorption in the oxygen absorption layer This is not preferable because the possibility that low-molecular substances generated as a result of oxidation of the substance to be oxidized will diffuse toward the packaged object will increase. For these reasons, the oxygen absorption rate is preferably 100 cc / (m ² · day) or less, and more preferably 50 cc / (m ² · day) or less.

  Hereinafter, the oxygen-absorbing resin composition (P) constituting the oxygen-absorbing layer in the packaging material of the present invention will be described.

  The oxygen-absorbing resin composition (P) contains an ethylene-vinyl alcohol copolymer as a matrix resin. Hereinafter, the oxygen-absorbing resin composition (P) may be simply abbreviated as the resin composition (P), and the ethylene-vinyl alcohol copolymer may be abbreviated as EVOH. By using EVOH as the matrix resin, it is possible to remarkably prevent the odorous substance generated particularly when the oxidizable substance in the resin composition (P) is oxidized into the package. The reason why EVOH has an effect superior to that of other gas barrier resins is not clear, but substances that are generated by oxidation of oxidizable substances and have strong odor are aldehydes, ketones, carboxylic acids, etc., all of which are EVOH Therefore, it is presumed that it has an excellent odor preventing effect when adsorbed in the resin composition (P).

  Since EVOH has gas barrier properties, it blocks oxygen from outside the packaging material and maintains the oxygen absorption function of the packaging material for a long period of time. From the viewpoint of gas barrier properties, the ethylene content of EVOH is preferably 5 to 60 mol%. When the ethylene content is less than 5 mol%, the gas barrier property under high humidity may be lowered and the melt moldability may be deteriorated. The ethylene content of EVOH is preferably 10 mol% or more, more preferably 15 mol% or more, and most preferably 20 mol% or more. On the other hand, if the ethylene content exceeds 60 mol%, sufficient gas barrier properties may not be obtained. The ethylene content is preferably 55 mol% or less, and more preferably 50 mol% or less.

  On the other hand, for the purpose of the present invention, when the barrier property of EVOH is extremely high, it may be difficult to make the oxygen absorption rate above a certain level. From the viewpoint of increasing the EVOH amount in the resin composition (P) to an appropriate level and obtaining an appropriate oxygen absorption rate, the ethylene content of EVOH is preferably 33 mol% or more. Further, from the viewpoint of preventing the diffusion of the odorous substance, the ethylene content is preferably small to some extent. In this aspect, the ethylene content is preferably 46 mol% or less.

  EVOH has a high gas barrier property at low humidity, but has a property that gas is more easily transmitted as the humidity increases. In view of this, the resin composition (P) almost absorbs oxygen if the molding conditions and storage conditions are kept at a low humidity even though the gas permeates to some extent at normal humidity and therefore the oxygen absorption rate is high. Not shown and rarely deteriorates.

  Similarly, from the viewpoint of gas barrier properties, the saponification degree of EVOH is preferably 90% or more, more preferably 95% or more, and further preferably 99% or more.

  EVOH suitably used has an ethylene content of 5 to 60 mol% and a saponification degree of 90% or more as described above. When a multilayer container containing the resin composition of the present invention is desired to have excellent impact peel resistance, the ethylene content is 25 mol% or more and 55 mol% or less, and the saponification degree is 90% or more and 99% or less. It is preferred to use less than EVOH.

  When EVOH consists of a mixture of two or more types of EVOH having different ethylene contents, the average value calculated from the mixture mass ratio is taken as the ethylene content. In this case, it is preferable that the difference in ethylene content between EVOHs having the most distant ethylene contents is 30 mol% or less and the difference in the degree of saponification is 10% or less. When these conditions are not met, the transparency of the resin composition may be impaired. The difference in ethylene content is more preferably 20 mol% or less, and even more preferably 15 mol% or less. Further, the difference in the degree of saponification is more preferably 7% or less, and further preferably 5% or less. In the multilayer container containing the resin composition of the present invention, when it is desired to have a balance at a higher level of impact resistance and gas barrier properties, the ethylene content is 25 mol% or more and 55 mol% or less, EVOH (b′1) having a saponification degree of 90% or more and less than 99%, and EVOH (b′2) having an ethylene content of 25 mol% or more and 55 mol% or less and a saponification degree of 99% or more. It is preferable to use the mixture so that the blending mass ratio b′1 / b′2 is 5/95 to 95/5.

  The ethylene content and saponification degree of EVOH can be determined by a nuclear magnetic resonance (NMR) method.

  The EVOH can also contain a small amount of monomer units other than ethylene units and vinyl alcohol units as copolymerized units, as long as the object of the present invention is not impaired. Examples of such monomers include the following compounds: α-olefins such as propylene, 1-butene, isobutene, 4-methyl-1-pentene, 1-hexene, 1-octene; itaconic acid, Unsaturated carboxylic acids such as methacrylic acid, acrylic acid, maleic anhydride, salts thereof, partial or complete esters thereof, nitriles, amides thereof, anhydrides thereof; vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri (β-methoxy) -Ethoxy) silanes, vinylsilane compounds such as γ-methacryloxypropyltrimethoxysilane; unsaturated sulfonic acids or salts thereof; alkylthiols; vinylpyrrolidones.

  Among them, when EVOH contains 0.0002 to 0.2 mol% of a vinylsilane compound as a copolymerization component, the composition of the present invention containing the EVOH is used as a resin (for example, polyester; In the present specification, polyester may be abbreviated as PES), and when co-extrusion molding or co-injection molding is used to obtain a multilayer structure, the consistency of the melt viscosity with the base resin is improved, and homogeneous Can be manufactured. As the vinylsilane compound, vinyltrimethoxysilane, vinyltriethoxysilane, or the like is preferably used.

  It is also preferable to modify EVOH by a conventionally known method in order to impart flexibility to EVOH. In this case, even if the gas barrier property is somewhat sacrificed by the modification for imparting flexibility, the oxygen absorption rate is improved by adjusting the composition and manufacturing method of the oxygen-absorbing resin composition (P). It is also possible. As such a modified EVOH or a resin composition containing the same, a modified EVOH described in Patent Document 5 and a resin composition containing the same can be used.

  Furthermore, when a boron compound is added to EVOH, it is effective in that the melt viscosity of EVOH is improved and a homogeneous co-extruded or co-injected molded article can be obtained. Examples of the boron compound include boric acids, boric acid esters, borates, and borohydrides. Specifically, boric acids include orthoboric acid (hereinafter sometimes abbreviated as boric acid), metaboric acid, tetraboric acid and the like, and boric acid esters include triethyl borate, trimethyl borate and the like. Examples of the borate include alkali metal salts, alkaline earth metal salts, and borax of the various boric acids described above. Of these compounds, orthoboric acid is preferred.

  When a boron compound is added, the content thereof is preferably 20 to 2000 ppm, more preferably 50 to 1000 ppm in terms of boron element. By being in this range, EVOH in which torque fluctuation during heating and melting is suppressed can be obtained. If it is less than 20 ppm, such an effect is small. On the other hand, if it exceeds 2000 ppm, gelation tends to occur and moldability may be deteriorated.

  Adding an alkali metal salt to EVOH, preferably 5 to 5000 ppm in terms of alkali metal element, is also effective for improving interlayer adhesion and compatibility. The addition amount of the alkali metal salt is more preferably 20 to 1000 ppm, further preferably 30 to 500 ppm in terms of alkali metal element. Examples of the alkali metal include lithium, sodium, and potassium, and examples of the alkali metal salt include an aliphatic metal carboxylate, an aromatic carboxylate, a phosphate, and a metal complex. For example, sodium acetate, potassium acetate, sodium phosphate, lithium phosphate, sodium stearate, potassium stearate, sodium salt of ethylenediaminetetraacetic acid, etc. Among these, sodium acetate, potassium acetate, sodium phosphate are preferred. is there.

  It is also preferable to add the phosphoric acid compound to EVOH in a proportion of preferably 20 to 500 ppm, more preferably 30 to 300 ppm, and most preferably 50 to 200 ppm in terms of phosphate radical. By blending the phosphoric acid compound within the above range, the thermal stability of EVOH can be improved. In particular, it is possible to suppress the occurrence of gelled spots and coloring when performing melt molding for a long time.

  The kind of phosphoric acid compound added to EVOH is not particularly limited, and various acids such as phosphoric acid and phosphorous acid and salts thereof can be used. The phosphate may be in any form of primary phosphate, secondary phosphate, and tertiary phosphate. The cationic species of the phosphate is not particularly limited, but the cationic species is preferably an alkali metal or alkaline earth metal. Among these, it is preferable to add the phosphorus compound in the form of sodium dihydrogen phosphate, potassium dihydrogen phosphate, disodium hydrogen phosphate, or dipotassium hydrogen phosphate.

  EVOH has a suitable melt flow rate (MFR) (at 210 ° C. under 2160 g load, based on JIS K7210) of 0.1 to 100 g / 10 min, more preferably 0.5 to 50 g / 10 min, more preferably 1-30 g / 10 min.

  Next, the thermoplastic resin (A1) constituting the resin composition (P) and having a carbon-carbon double bond substantially only in the main chain will be described. Hereinafter, the thermoplastic resin (A1) having a carbon-carbon double bond substantially only in the main chain may be referred to as a thermoplastic resin (A1).

  The thermoplastic resin (A1) has a carbon-carbon double bond substantially only in the main chain. Here, the thermoplastic resin “substantially having a carbon-carbon double bond only in the main chain” means that the ratio of the carbon-carbon double bonds of the thermoplastic resin (A1) existing in the side chain is It means 10 mol% or less. The proportion of carbon-carbon double bonds present in the side chain is preferably 7 mol% or less, more preferably 5% or less.

  Examples of such thermoplastic resin (A1) are polydienes such as polybutadiene, polyisoprene, polychloroprene, poly (2-ethylbutadiene), poly (2-butylbutadiene), and are mainly polymerized at the 1,4-positions. Furthermore, ring-opening metathesis polymers of cycloolefins such as polyoctenylene, polypentenylene and polynorbornene can be exemplified. Among these, 1,4-polybutadiene and polyoctenylene are preferable.

  Here, generally, when the carbon-carbon double bond is present in the main chain, the oxygen absorption amount and the absorption rate as much as those present in the side chain are often not obtained. However, in a thermoplastic resin having a carbon-carbon double bond in the main chain and a repeating unit in which three or more methylene chains exist between adjacent carbon-carbon double bonds, The amount of oxygen absorbed per heavy bond was larger than expected. Therefore, in the packaging material of the present invention, it is difficult to generate odor, and from the viewpoint that a high oxygen absorption rate can be obtained with a small addition amount, the thermoplastic resin (A1) is between adjacent carbon-carbon double bonds. A thermoplastic resin having a repeating unit in which three or more methylene chains are present is preferred. Examples of such a suitable thermoplastic resin include polyoctenylene and polypentenylene, and polyoctenylene is particularly preferable.

  The amount of carbon-carbon double bonds contained in the thermoplastic resin (A1) is preferably 0.001 eq / g (equivalent / g) or more, more preferably 0.005 eq / g or more, and 0.01 eq / g. g or more is more preferable. When the content of the carbon-carbon double bond is less than 0.001 eq / g, there is a possibility that sufficient oxygen absorption ability cannot be obtained.

  From the above viewpoint, the number average molecular weight of the thermoplastic resin (A1) is preferably 1,000 to 500,000, more preferably 5,000 to 300,000, still more preferably 10,000 to 250,000, and particularly preferably 40000. It is in the range of ~ 200000. When the molecular weight is less than 1000 or more than 50000, the resulting resin composition is inferior in molding processability and handling property, or mechanical properties such as strength and elongation when formed into a molded body may be reduced. There is. Further, when used in combination with EVOH, the dispersibility is lowered, and as a result, the oxygen scavenging function may be lowered.

  When the thermoplastic resin (A1) is a ring-opening metathesis polymer of a cyclic olefin, it is unavoidable that a certain amount of oligomers are inevitably mixed due to the mechanism of the ring-opening metathesis polymerization. Under normal conditions of use, if the monomer is removed, problems such as odor are unlikely to occur. However, when performing retort treatment, hot water treatment, etc., the presence of these oligomers may cause odor to be felt in the package. Accordingly, when performing retorting or the like, the amount of oligomer having a molecular weight of 1000 or less in the ring-opening metathesis polymer is preferably 6% by weight or less, more preferably 4% by weight or more preferably 2% by weight or less. By making the oligomer having a molecular weight of 1000 or less 6% by weight or less, when it is dispersed in another polymer used in the application of the present invention, the elution amount is remarkably reduced, and the packaging material has a high temperature together with water after molding. It was confirmed that the odor of water when the treatment was performed was reduced. On the other hand, the amount of oligomer should be low from the viewpoint of odor and the like, but if it is attempted to be lower than necessary, the difficulty in the process increases, so it may be 0.5% by weight or more in practical use, and it is more practical. If weight is important, it may be 1% by weight or more.

  Examples of a method for removing the oligomer from the ring-opening metathesis polymer include a method of washing and removing with an organic solvent such as acetone.

  The thermoplastic resin (A1) may contain an antioxidant. Examples of the antioxidant include the following compounds. 2,5-di-tert-butylhydroquinone, 2,6-di-tert-butyl-p-cresol, 4,4′-thiobis- (6-tert-butylphenol), 2,2′-methylene-bis- ( 4-methyl-6-tert-butylphenol), octadecyl-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate, 4,4′-thiobis- (6-tert-butylphenol) 2-tert-butyl-6- (3-tert-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, pentaerythritol tetrakis (3-laurylthiopropionate), 2,6-di -(Tert-butyl) -4-methylphenol (BHT), 2,2-methylenebis- (6-tert-butyl) -p- cresol), triphenyl phosphite, phosphorous acid tris - (nonylphenyl), such as dilauryl thiodipropionate can be exemplified.

  The amount of the antioxidant contained in the thermoplastic resin (A1) is appropriately determined in consideration of the type and content of each component in the resin composition, the purpose of use of the resin composition, storage conditions, and the like. Usually, the amount of the antioxidant is preferably 0.01 to 1% by mass, and 0.02 to 0.5% by mass based on the total mass of the thermoplastic resin (A1) and the antioxidant. It is more preferable. When the amount of the antioxidant is too large, the reaction between the thermoplastic resin (A1) and oxygen is hindered, so that the oxygen scavenging function of the resin composition of the present invention may be insufficient. On the other hand, if the amount of the antioxidant is too small, the reaction with oxygen proceeds during storage or melt-kneading of the thermoplastic resin (A1), and the oxygen scavenging function decreases before actual use of the resin composition. May end up.

  The ratio of the thermoplastic resin (A1) and EVOH in the oxygen-absorbing resin composition (P) is appropriately determined according to the required performance. However, if the amount of the thermoplastic resin (A1) is too small, oxygen is absorbed. In some cases, the speed and the amount of absorption cannot be sufficiently obtained. If the amount is too large, the gas permeability of the oxygen-absorbing resin composition (P) becomes too high, and the physical properties associated with the oxidation of the thermoplastic resin (A1). There is a concern that a decrease in color and a change in hue are likely to occur.

  In view of such points, the ratio of the amount of the thermoplastic resin (A1) and EVOH in the oxygen-absorbing resin composition (P) is 100% by mass of the total mass of the thermoplastic resin (A1) and EVOH. When it does, it is preferable to contain 1-30 mass% of thermoplastic resins (A1), More preferably, it is 2-20 mass%, More preferably, it is 3-15 mass%.

  The oxygen-absorbing resin composition (P) may contain an oxidation accelerator in addition to EVOH and the thermoplastic resin (A1). The oxidation accelerator (C) is not particularly limited as long as it promotes the reaction between the thermoplastic resin (A1) and molecular oxygen. Examples of such oxidation promoters include radical generators, photooxidation catalysts, transition metal salts, and the like. Among these, the transition metal salt (C1) is preferably used because it is effective in a small amount. The presence of the oxidation accelerator promotes the oxidation of the thermoplastic resin (A1) and improves the oxygen absorption function of the oxygen-absorbing resin composition (P).

  Examples of the transition metal contained in the transition metal salt (C1) include, but are not limited to, iron, nickel, copper, manganese, cobalt, rhodium, titanium, chromium, vanadium, and ruthenium. Among these, iron, nickel, copper, manganese, and cobalt are preferable, manganese and cobalt are more preferable, and cobalt is still more preferable.

  Examples of the counter ion of the metal contained in the transition metal salt (C1) include an anion derived from an organic acid or chloride. Examples of the organic acid include acetic acid, stearic acid, acetylacetone, dimethyldithiocarbamic acid, palmitic acid, 2-ethylhexanoic acid, neodecanoic acid, linoleic acid, toluic acid, oleic acid, resin acid, capric acid, naphthenic acid and the like. However, it is not limited to these. Particularly preferred salts include cobalt 2-ethylhexanoate, cobalt neodecanoate and cobalt stearate. The metal salt may be a so-called ionomer having a polymeric counter ion.

  The transition metal salt (C1) is preferably contained at a ratio of 1 to 50000 ppm in terms of a mass ratio in terms of metal element, based on the total mass of EVOH and the thermoplastic resin (A1). Further, when the resin composition (P) contains the compatibilizer (D) in addition to EVOH and the thermoplastic resin (A1), the transition metal salt (C1) is preferably EVOH, heat Based on the total amount of the plastic resin (A1) and the compatibilizer (D), it is contained in a ratio of 1 to 50000 ppm in terms of metal element. More preferably, the transition metal salt (C1) is contained in the range of 5 to 10,000 ppm, more preferably 10 to 5000 ppm. When the content of the transition metal salt (C1) is less than 1 ppm, the oxygen absorption effect of the resin composition (P) may be insufficient. On the other hand, when the content of the transition metal salt (C1) exceeds 50000 ppm, the thermal stability of the resin composition is lowered, and the generation of decomposition gas and the generation of gels and blisters may become remarkable.

  The oxygen-absorbing resin composition (P) may contain a compatibilizer (D) in addition to EVOH and the thermoplastic resin (A1).

  The compatibilizer (D) includes EVOH and the thermoplastic resin (A1) in the resin composition (P), or, if necessary, other resins, and other resins. In order to improve the compatibility of the resin and to give a stable morphology to the resulting resin composition, it is contained as necessary. The type of the compatibilizer (D) is not particularly limited, and is appropriately selected depending on the combination of the type of EVOH to be used, the thermoplastic resin (A1), and the like.

  The compatibilizer (D) is preferably a hydrocarbon polymer or an ethylene-vinyl alcohol copolymer containing a polar group. For example, when the compatibilizer (D) is a hydrocarbon-based polymer containing a polar group, the compatibilizer (D) and the thermoplastic resin (by the hydrocarbon polymer portion serving as the base of the polymer) Affinity with A1) is improved. Furthermore, the affinity between the compatibilizer (D) and EVOH is improved by the polar group of the compatibilizer (D). As a result, a stable morphology can be formed in the obtained resin composition.

  Examples of the monomer capable of forming the hydrocarbon polymer portion serving as the base of the hydrocarbon polymer containing the polar group include the following compounds: ethylene, propylene, 1-butene, isobutene, 3- Α-olefins such as methylpentene, 1-hexene, 1-octene; styrene, α-methylstyrene, 2-methylstyrene, 4-methylstyrene, 4-propylstyrene, 4-tert-butylstyrene, 4-cyclohexylstyrene 4-dodecylstyrene, 2-ethyl-4-benzylstyrene, 4- (phenylbutyl) styrene, 2,4,6-trimethylstyrene, monofluorostyrene, difluorostyrene, monochlorostyrene, dichlorostyrene, methoxystyrene, tert- Styrenes such as butoxystyrene; 1-vinylnaphthalene Vinyl naphthalenes such as 2-vinylnaphthalene; vinylene group-containing aromatic compounds such as indene and acenaphthylene; conjugated diene compounds such as butadiene, isoprene, 2,3-dimethylbutadiene, pentadiene and hexadiene. The hydrocarbon polymer may mainly contain one of these monomers, or may mainly contain two or more.

  Using the monomer, a hydrocarbon polymer containing a polar group is prepared, and the monomer forms a hydrocarbon polymer portion composed of the following polymer: polyethylene (ultra-low Density, low density, linear low density, medium density, high density), ethylene- (meth) acrylic acid ester (methyl ester, ethyl ester, etc.) copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol Olefin polymers such as copolymer, polypropylene, ethylene-propylene copolymer; polystyrene, styrene-acrylonitrile copolymer, styrene-acrylonitrile-butadiene copolymer, styrene-diene block copolymer (styrene-isoprene block) Copolymer, styrene-butadiene copolymer, styrene-isoprene-styrene block copolymer Etc.), styrene polymers such as hydrogenated products thereof; (meth) acrylic acid ester polymers such as polymethyl acrylate, polyethyl acrylate and polymethyl methacrylate; vinyl halides such as polyvinyl chloride and vinylidene fluoride Polymers: Semi-aromatic polyesters such as polyethylene terephthalate and polybutylene terephthalate; Aliphatic polyesters such as polyvalerolactone, polycaprolactone, polyethylene succinate, and polybutylene succinate. Among these, styrene polymers such as styrene-diene block copolymers (styrene-isoprene block copolymers, styrene-butadiene copolymers, styrene-isoprene-styrene block copolymers, etc.) and hydrogenated products thereof. Is preferred.

The polar group contained in the compatibilizer (D) is not particularly limited, but a functional group containing an oxygen atom is preferable. Specifically, polar groups that contain active hydrogen-containing polar groups (such as —SO ₃ H, —SO ₂ H, —SOH, —CONH ₂ , —CONHR, —CONH—, —OH, etc.) and no active hydrogen. Group (—NCO, —OCN, —NO, —NO ₂ , —CONR ₂ , —CONR—, etc.), epoxy group, carbonyl group-containing polar group (—CHO, —COOH, —COOR, —COR,> C═O , -CSOR, -CSOH, etc.), phosphorus-containing polar groups (-P (OR) ₂ , -PO (OR) ₂ , -PO (SR) ₂ , -PS (OR) ₂ , -PO (SR) (OR) , -PS (SR) (OR), etc.), boron-containing polar groups, and the like. Here, in said general formula, R represents an alkyl group, a phenyl group, or an alkoxy group.

  Such a compatibilizer having a polar group is disclosed in detail in, for example, Patent Document 4. Among the compatibilizers disclosed, styrene-hydrogenated diene block copolymers having a boronic ester group are preferred.

  The oxygen-absorbing resin composition (P) is preferably mainly composed of EVOH (B) and a thermoplastic resin (A1) substantially having a carbon-carbon double bond in the main chain. Based on the total mass of the oxygen-absorbing resin composition (P), the total amount of EVOH (B) and the thermoplastic resin (A1) is preferably 90% by mass or more, more preferably 95% by mass or more. preferable. In the case of containing the compatibilizer (D), EVOH (B), the thermoplastic resin (A1), and the compatibilizer (D) are based on the total mass of the oxygen-absorbing resin composition (P). The total amount is preferably 90% by mass or more, and more preferably 95% by mass or more.

  The oxygen-absorbing resin composition (P) may contain various additives as long as the effects of the present invention are not inhibited. Examples of such additives include antioxidants, plasticizers, heat stabilizers (melt stabilizers), photoinitiators, deodorants, UV absorbers, antistatic agents, lubricants, colorants, fillers, desiccants. , Fillers, pigments, dyes, processing aids, flame retardants, antifogging agents, and other polymer compounds. Such an additive is disclosed in detail in, for example, Patent Document 4.

  In the oxygen-absorbing resin composition (P), an embodiment in which particles made of the thermoplastic resin (A1) are dispersed in EVOH is recommended. The packaging material of the present invention comprising the composition in such a state is preferable in that the oxygen scavenging property and the oxygen barrier property are easily maintained, and the function possessed by EVOH can be imparted. Transparency is also good. At this time, it is preferable that the average particle diameter of the particles made of the thermoplastic resin (A1) is 10 μm or less. When the average particle diameter exceeds 10 μm, the area of the interface between the thermoplastic resin (A1) and EVOH becomes small, and the oxygen gas barrier property and the oxygen scavenging function may be lowered. The average particle size of the thermoplastic resin (A1) particles is more preferably 5 μm or less, and even more preferably 2 μm or less.

  In order to realize the above-described embodiment and to exhibit excellent oxygen barrier properties and low odor, the number average molecular weight of the thermoplastic resin (A1) having a carbon-carbon double bond in the main chain is 1000 to 500,000. More preferably, it is in the range of 5,000 to 300,000, more preferably 10,000 to 250,000, and particularly preferably 40,000 to 200,000. Moreover, it is preferable that the thermoplastic resin (A1) is not substantially crosslinked.

  Further, in order to improve the affinity with EVOH, the thermoplastic resin (A1) may be a hydrophilic functional group (hydroxyl group, alkoxy group having 1 to 10 carbon atoms, amino group, aldehyde group, carboxyl group, epoxy group, It preferably has an ester group, a carboxylic acid anhydride group, or a boron-containing polar group (for example, a boronic acid group, a boronic acid ester group, a boronic acid anhydride group, a boronic acid group), and particularly a hydroxyl group, an epoxy group, an acid It preferably has an anhydride group.

  Furthermore, when the oxygen-absorbing resin composition (P) contains an appropriate amount of the compatibilizer (D), the above effects are easily obtained stably.

Suitable melt flow rate (MFR) (210 ° C., 2 ° C.) of the oxygen-absorbing resin composition of the present invention
Under a load of 160 g, based on JIS K7210) is 0.1 to 100 g / 10 minutes, more preferably 0.5 to 50 g / 10 minutes, and further preferably 1 to 30 g / 10 minutes. When the melt flow rate of the resin composition of the present invention is out of the above range, the workability during melt molding often deteriorates.

  Each said component is mixed and processed into the packaging material of this invention. The method and order of mixing the components of the oxygen-absorbing resin composition (P) are not particularly limited.

  As a specific method of mixing, a melt-kneading method is preferable from the viewpoints of process simplicity and cost. At this time, using an apparatus capable of achieving a high degree of kneading and dispersing each component finely and uniformly can improve oxygen absorption performance and transparency, and can prevent the occurrence of gels and blisters. This is preferable.

  Equipment that can achieve a high degree of kneading includes continuous intensive mixers, kneading type twin-screw extruders (in the same direction or in different directions), mixing rolls, and kneaders, etc .; high-speed mixers, Banbury mixers, intensive mixers , Batch type kneaders such as pressure kneaders; equipment using a rotating disk having a grinding mechanism such as a stone mill such as KCK kneading extruder made by KCK Co., Ltd., kneading part (Dalmage, CTM Etc.); simple kneaders such as a ribbon blender and a Brabender mixer. Among these, a continuous kneader is preferable. Examples of commercially available continuous intensive mixers include FCM manufactured by Farrel, CIM manufactured by Nippon Steel Works, Ltd., KCM, LCM, and ACM manufactured by Kobe Steel Corporation. It is preferable to employ a device in which a single screw extruder is installed under these kneaders, and kneading and extrusion pelletization are simultaneously performed. Examples of the twin-screw kneading extruder having a kneading disk or a kneading rotor include, for example, TEX manufactured by Nippon Steel, ZSK manufactured by Werner & Pfleiderer, TEM manufactured by Toshiba Machine Co., Ltd., PCM manufactured by Ikekai Tekko Co., Ltd. Is mentioned. One kneader may be used, or two or more kneaders may be connected and used.

  The kneading temperature is usually in the range of 50 to 300 ° C. In order to prevent oxidation of the thermoplastic resin (A1), it is preferable that the hopper port is sealed with nitrogen and extruded at a low temperature. The longer the kneading time, the better results can be obtained, but from the viewpoint of the antioxidant and production efficiency of the thermoplastic resin (A1), it is usually 10 to 600 seconds, preferably 15 to 200 seconds, more preferably. 15 to 150 seconds.

  In molding the packaging material of the present invention, the oxygen-absorbing resin composition (P) is molded into various molded products such as films, sheets, containers, and other packaging materials by appropriately adopting a molding method. can do. At this time, the resin composition (P) may be once formed into pellets and then subjected to molding, or each component of the resin composition (P) may be dry blended and directly subjected to molding.

  As a molding method and a molded product, for example, it can be formed into a film, sheet, pipe or the like by melt extrusion molding, into a container shape by injection molding, or into a hollow container such as a bottle shape by hollow molding. Examples of hollow molding include extrusion hollow molding in which a parison is molded by extrusion molding and blown to perform molding, and injection hollow molding in which a preform is molded by injection molding and blown to perform molding. it can. Among these, for the retort packaging material, a method of forming a packaging material such as a multilayer film by melt extrusion molding, or a method of thermoforming a multilayer sheet formed by melt extrusion molding into a container-like packaging material is preferably used. . In addition, depending on the application, a method of forming a parison by extrusion molding and blow-molding the parison to form a relatively flexible multilayer container-like packaging material is also preferably used.

  In the packaging material of the present invention, the molded product obtained by the above molding is laminated with other layers and used as a multilayer structure.

  As a layer structure of the multilayer structure, a layer made of a resin other than the oxygen absorbing resin composition (P) is an x layer, an oxygen absorbing resin composition layer (P) is a y layer, and an adhesive resin layer is a z layer. Then, x / y, x / y / x, x / z / y, x / z / y / z / x, x / y / x / y / x, x / z / y / z / x / z / Although y / z / x etc. are illustrated, it is not limited to these. When a plurality of x layers are provided, the types may be the same or different. Further, a layer using a recovered resin made of scrap such as trim generated during molding may be separately provided, or the recovered resin may be blended with a layer made of another resin. Although the thickness structure of each layer of the multilayer structure is not particularly limited, the thickness ratio of the y layer to the total layer thickness is preferably 2 to 20% from the viewpoint of moldability and cost.

  The resin used for the x layer is preferably a thermoplastic resin from the viewpoint of processability. Such thermoplastic resins include, but are not limited to, the following resins: polyethylene, polypropylene, ethylene-propylene copolymer, ethylene or propylene copolymer (at least one of the following monomers with ethylene or propylene): Copolymer with one kind: α-olefin such as 1-butene, isobutene, 4-methyl-1-pentene, 1-hexene, 1-octene; non-condensation such as itaconic acid, methacrylic acid, acrylic acid, maleic anhydride Saturated carboxylic acid, salt, partial or complete ester thereof, nitrile, amide, anhydride thereof; vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl octanoate, vinyl dodecanoate, vinyl stearate Carboxylic acid vinyl esters such as vinyl arachidonate; Vinyl silane compounds such as nyltrimethoxysilane; unsaturated sulfonic acids or salts thereof; alkyl thiols; vinyl pyrrolidones, etc.), polyolefins such as poly-4-methyl-1-pentene, poly-1-butene; polyethylene terephthalate, polybutylene Polyesters such as terephthalate and polyethylene naphthalate; Polyamides such as poly ε-caprolactam, polyhexamethylene adipamide, and polymethaxylylene adipamide; polyvinylidene chloride, polyvinyl chloride, polystyrene, polyacrylonitrile, polycarbonate, polyacrylate, and the like. Such a thermoplastic resin layer may be unstretched, or may be stretched or rolled uniaxially or biaxially.

  Among these resins, as a packaging material for foods and the like, from the viewpoint of absorbing oxygen inside the packaging material, the resin forming the inner layer of the packaging material is preferably a hydrophobic resin having a relatively high gas permeability, Depending on the case, heat sealing is preferable. From such a viewpoint, as the resin on the inner layer side, polyolefin such as polyethylene and polypropylene, ethylene-vinyl acetate copolymer, and the like are preferably used. On the other hand, as the resin constituting the outer layer, those having excellent moldability and mechanical properties are preferable. For example, polyolefins such as polyethylene and polypropylene, polyamides, and polyesters are preferably used.

  Among these resins, the resin suitably used when the packaging material of the present invention is used as a packaging material for retort is polyamide, polyester, or polypropylene on the outer layer side when packaging food or the like into a package. Polypropylene is particularly preferred. Polypropylene is preferably used on the inner layer side.

  Of these thermoplastic resins, polyolefin is preferable in terms of moisture resistance, mechanical properties, economy, heat sealability, and the like, and polyester is preferable in terms of mechanical properties, heat resistance, and the like.

  On the other hand, the adhesive resin used for the z layer is not particularly limited as long as it can bond the respective layers, and a polyurethane-based or polyester-based one-component or two-component curable adhesive, carboxylic acid-modified polyolefin Resins are preferably used. The carboxylic acid-modified polyolefin resin is an olefin polymer or copolymer containing an unsaturated carboxylic acid or its anhydride (such as maleic anhydride) as a copolymerization component; or an unsaturated carboxylic acid or its anhydride as an olefin polymer. Or it is a graft copolymer obtained by grafting to a copolymer.

  Among these, carboxylic acid-modified polyolefin resin is more preferable. In particular, when the x layer is a polyolefin resin, the adhesion with the y layer is good. Examples of such carboxylic acid-modified polyolefin resins include polyethylene {low density polyethylene (LDPE), linear low density polyethylene (LLDPE), very low density polyethylene (VLDPE)}, polypropylene, copolymer polypropylene, ethylene-vinyl acetate. Examples include copolymers and ethylene- (meth) acrylic acid ester (methyl ester or ethyl ester) copolymers that have been modified with a carboxylic acid.

  Examples of the method for obtaining the multilayer structure include an extrusion laminating method, a dry laminating method, a co-injection molding method, and a co-extrusion molding method, but are not particularly limited. Examples of the coextrusion molding method include a coextrusion lamination method, a coextrusion sheet molding method, a coextrusion inflation molding method, and a coextrusion blow molding method.

  The sheet, film, parison, etc. of the multilayer structure thus obtained are reheated at a temperature below the melting point of the contained resin, thermoforming methods such as drawing, roll stretching methods, pantograph type stretching methods, A stretched molded product can be obtained by uniaxial or biaxial stretching by an inflation stretching method, a blow molding method, or the like.

  A molded product using the multilayer structure is used as the packaging material of the present invention. Furthermore, in this invention, the multilayer structure which has arrange | positioned the layer with high water vapor | steam barrier property on the both sides of the layer which consists of oxygen-absorbing resin composition (P), or the side which becomes high humidity when using this packaging material Is preferred from the standpoint that the duration of the oxygen scavenging function is particularly prolonged and, as a result, very high gas barrier properties are continued for a longer time. On the other hand, a multilayer container having an oxygen-absorbing resin composition (P) layer as the innermost layer is suitable from the viewpoint that the oxygen scavenging function in the container is rapidly exhibited.

  Furthermore, the transparency of the oxygen-absorbing resin composition (P) is improved by selecting an appropriate resin. Therefore, such a composition is most suitable for the use as a packaging container in which the contents are easily visually recognized among the packaging materials of the present invention. Among such packaging containers, the required performance with respect to transparency is strict, and the following two types of modes can be cited as modes in which the usefulness of using the resin composition of the present invention is great. That is, one is a container made of a multilayer film including a layer made of the resin composition of the present invention and having a total layer thickness of 300 μm or less, and the other is a layer made of the resin composition of the present invention and thermoplasticity. A multilayer container including at least one polyester (PES) layer. Hereinafter, these embodiments will be sequentially described.

  Among the packaging materials of the present invention, a container made of a multilayer film including a layer made of the oxygen-absorbing resin composition (P) and having a total layer thickness of 300 μm or less consists of a multilayer structure having a relatively thin total layer thickness. It is a flexible container and is usually processed into a form such as a pouch. This container has excellent gas barrier properties, has a continuous oxygen scavenging function, and is easy to manufacture. Therefore, it is extremely useful for packaging products that are highly sensitive to oxygen and easily deteriorated.

  In a thin multilayer film having a total layer thickness of 300 μm or less, even if the transparency decreases with time, the degree is small, and as a result, the transparency of the multilayer film container is maintained. From the viewpoint of maintaining transparency and flexibility, the thickness of such a multilayer film is usually 300 μm or less, more preferably 250 μm or less, and even more preferably 200 μm or less, as described above. On the other hand, considering the mechanical properties of the container, the total layer thickness is preferably 10 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more.

  When a container composed of a multilayer film having a total layer thickness of 300 μm or less is produced from the multilayer film, there is no particular limitation on the production method of the multilayer film, for example, a thermoplastic resin layer with the resin composition layer of the present invention. A multilayer film can be obtained by laminating by a method such as dry lamination or coextrusion lamination.

  In the case of dry lamination, an unstretched film, a uniaxially stretched film, a biaxially stretched film, a rolled film, etc. can be used. Among these, a biaxially stretched polypropylene film, a biaxially stretched polyethylene terephthalate film, and a biaxially stretched polyε-caprolactam film are preferable from the viewpoint of mechanical strength, and a biaxially stretched polypropylene film is particularly preferable in consideration of moisture resistance. When using an unstretched film or a uniaxially stretched film, the multilayer film is reheated after being laminated, and uniaxially or biaxially stretched by a thermoforming method such as drawing, a roll stretching method, a pantograph stretching method, an inflation stretching method, or the like. Thus, a stretched multilayer film can be obtained.

  In order to seal the resulting multilayer container, it is also preferable to provide a layer made of a heat-sealable resin on at least one outermost surface in the production stage of the multilayer film. Examples of such resins include polyolefins such as polyethylene and polypropylene.

  The multilayer film obtained in this way is processed into a bag shape, for example, and can be used as a packaging container for filling the contents. Since it is flexible and simple, and is excellent in transparency and oxygen scavenging properties, it is extremely useful for packaging of contents that are easily deteriorated by the presence of oxygen, particularly foods and pet foods.

  Among the packaging materials of the present invention, a multilayer container including at least one layer composed of an oxygen-absorbing resin composition (P) and a PES layer is excellent in gas barrier properties and oxygen scavenging function, and further selects an appropriate resin. Therefore, transparency is improved. Therefore, it is used in various forms such as a bag-shaped container, a cup-shaped container, and a hollow molded container.

  The PES used in the multilayer container which is the packaging material of the present invention comprising the layer comprising the oxygen-absorbing resin composition (P) and the PES layer is composed mainly of aromatic dicarboxylic acids or their alkyl esters and diol. A condensation polymer is used. In particular, in order to achieve the object of the present invention, PES mainly composed of an ethylene terephthalate component is preferable. Specifically, the total ratio (mol%) of the terephthalic acid unit and the ethylene glycol unit is preferably 70 mol% or more, and 90 mol% or more with respect to the total number of moles of all units constituting the PES. Is more preferable. When the total proportion of the terephthalic acid unit and the ethylene glycol unit is less than 70 mol%, the resulting PES becomes amorphous, the mechanical strength is insufficient, and the contents are heated and filled after being drawn into a container ( When hot filling is performed, there is a risk that the heat shrinkage is large and it cannot be used. In addition, if solid phase polymerization is performed to reduce the oligomers contained in the resin, the resin is likely to become stuck due to softening of the resin, which may make production difficult. The PES may be a bifunctional compound unit other than a terephthalic acid unit and an ethylene glycol unit, specifically, a neopentyl glycol unit, a cyclohexane dimethanol unit, a cyclohexane dicarboxylic acid unit, an isophthalic acid unit, or a naphthalene dicarboxylic acid. An acid unit etc. can be contained in the range which does not generate | occur | produce said problem. There is no restriction | limiting in particular as a manufacturing method of such PES, A well-known method can be selected suitably.

  Although the manufacturing method of the multilayer container which is a packaging material of the present invention including at least one layer composed of the oxygen-absorbing resin composition (P) and the PES layer is not particularly limited, co-injection blow molding is performed. It is preferable to use from the viewpoint of productivity and the like. In co-injection blow molding, a container is manufactured by stretch-blow molding a container precursor (parison) obtained by co-injection molding.

  In the co-injection molding, usually, the resin that constitutes each layer of the multilayer structure is led into two concentric nozzles from two or more injection cylinders, and at the same time or alternately at different timings, Molding is performed by injection into the mold and performing a single clamping operation. For example, (1) First, a PES layer for inner and outer layers is injected, and then a resin composition as an intermediate layer is injected to obtain a molded container having a three-layer structure of PES / resin composition / PES, (2 ) First, the PES layer for the inner and outer layers is injected, then the resin composition is injected, and at the same time or after that, the PES layer is injected again, and five layers of PES / resin composition / PES / resin composition / PES are injected. Although the parison is manufactured by a method for obtaining a molded container having a configuration, the parison is not limited to these manufacturing methods. Moreover, in the said layer structure, you may arrange | position an adhesive resin layer between a resin composition layer and a PES layer as needed.

  As conditions for injection molding, PES is preferably injected in a temperature range of 250 to 330 ° C, more preferably 270 to 320 ° C, and still more preferably 280 to 310 ° C. When the injection temperature of PES is less than 250 ° C., PES is not sufficiently melted, and an unmelted product (fish eye) is mixed into the molded product, resulting in poor appearance, and at the same time, the mechanical strength of the molded product is reduced. There is a risk of becoming. In extreme cases, the screw torque increases, which may cause a failure of the molding machine. On the other hand, when the injection temperature of PES exceeds 330 ° C., the decomposition of PES becomes remarkable, which may cause a decrease in mechanical strength of the molded product due to a decrease in molecular weight. Further, not only the property of the substance filled in the molded product is deteriorated by a gas such as acetaldehyde generated at the time of decomposition, but also the oligomer generated at the time of decomposition may cause the mold to become heavily soiled and deteriorate the appearance of the molded product.

  The resin composition is preferably injected in a temperature range of 170 to 250 ° C, more preferably 180 to 240 ° C, and still more preferably 190 to 230 ° C. When the injection temperature of the resin composition is less than 170 ° C., the resin composition does not melt sufficiently, and an unmelted product (fish eye) may be mixed into the molded product, resulting in poor appearance. In extreme cases, the screw torque increases, which may cause a failure of the molding machine. On the other hand, when the injection temperature of the resin composition exceeds 250 ° C., the oxidation of the thermoplastic resin (A) proceeds, and the gas barrier property and oxygen scavenging function of the resin composition may be deteriorated. At the same time, the appearance of the molded product may be poor due to coloring or gelation, or the fluidity may be non-uniform or hindered by the decomposition gas or gelation, resulting in a missing portion of the resin composition layer. In an extreme case, injection molding becomes impossible due to the generation of a gelled product. In order to suppress the progress of oxidation during melting, it is also preferable to seal the raw material supply hopper with nitrogen.

  The resin composition may be supplied to the molding machine in the form of pellets in which raw material components are melt-blended in advance, or each dry-blended raw material component may be supplied to the molding machine.

  In the parison thus obtained, the total thickness is preferably 2 to 5 mm, and the total thickness of the resin composition layer is preferably 10 to 500 μm.

  The parison is reheated directly at a high temperature or using a heating element such as a block heater or an infrared heater, and then sent to a stretch blow process. After the heated parison is stretched 1 to 5 times in the longitudinal direction in the stretch blow step, the multilayer injection blow molded container of the present invention is manufactured by stretch blow molding 1 to 4 times with compressed air or the like. Can do. The temperature of the parison is preferably 75 to 150 ° C, more preferably 85 to 140 ° C, still more preferably 90 to 130 ° C, and most preferably 95 to 120 ° C. When the temperature of the parison exceeds 150 ° C., PES tends to be crystallized, and the resulting container may be whitened to deteriorate the appearance or increase the delamination of the container. On the other hand, when the temperature of the parison is less than 75 ° C., crazing occurs in the PES, and the transparency may be impaired due to a pearly tone.

  The total thickness of the trunk portion of the multilayer container thus obtained is generally 100 to 2000 μm, preferably 150 to 1000 μm, and can be properly used depending on the application. The total thickness of the resin composition layer at this time is preferably in the range of 2 to 200 μm, and more preferably 5 to 100 μm.

  Thus, the multilayer container which consists of the layer which consists of a resin composition (P) and the PES layer which is a packaging material of this invention is obtained. This container can obtain high transparency, is extremely excellent in gas barrier properties and oxygen scavenging function, and does not generate odor components due to oxygen absorption. Therefore, it is useful as a container for contents that easily deteriorate due to the presence of oxygen, such as foods and pharmaceuticals. In particular, it is extremely useful as a container for beverages such as food and beer that emphasize flavor.

  The packaging material of the present invention has excellent oxygen absorbability, and generation and movement of odorous substances accompanying oxidation are extremely small, so it is suitable for contents that are easily deteriorated by the influence of oxygen, such as foods and pharmaceuticals. Can be used. In particular, it is suitable as a packaging material for foods, beverages and pet foods that are particularly sensitive to quality changes.

  In the present invention, a package in which these contents are packaged with the packaging material of the present invention is provided.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated concretely, this invention is not limited to the following Example.

  Analysis and evaluation in Examples and Comparative Examples were performed as follows.

(1) Molecular structure of thermoplastic resin (A1) The structure was determined from the spectrum obtained by ¹ H-NMR (nuclear magnetic resonance) measurement using deuterated chloroform as a solvent. For the nuclear magnetic resonance measurement, a JNM-GX-500 type nuclear magnetic resonance measuring apparatus manufactured by JEOL Ltd. was used.

(2) Number average molecular weight of thermoplastic resin (A1) Measured by gel permeation chromatography (GPC) and expressed as a polystyrene equivalent value. Detailed measurement conditions are as follows.
<Analysis conditions>
Apparatus: Shodex gel permeation chromatography (GPC) SYSTEM-11
Column: KF-806L manufactured by Shodex
Column temperature: 40 ° C
Mobile phase: Tetrahydrofuran (THF) Flow rate 1.0 mL (milliliter, the same applies hereinafter) / min Run: 15 min Detector: RI
Filtration: 0.45 μm filter Concentration: 0.1%
Injection volume: 100 μL (microliter, the same applies hereinafter)
Sample: Polystyrene Analysis: Empower

[Synthesis Example 1] Synthesis of polyoctenylene (a-1) [Polymerization]
A glass three-necked flask equipped with a stirrer and a thermometer and having a volume of 5 L (liter, hereinafter the same) was replaced with dry nitrogen, and then replaced with 110 g (1 mol) of cis-cyclooctene and 187 mg of cis-4-octene (1 .67 mmol) was dissolved in 624 g of heptane.

  Next, 42.4 mg (49.9 μmol) of [1,3-bis- (2,4,6-trimethylphenyl) -2-imidazolidinylidene] dichloro (phenylmethylene) (tricyclohexylphosphine) ruthenium was added to toluene 3. A catalyst solution dissolved in 00 g was prepared, and this was quickly added to the above heptane solution, and ring-opening metathesis polymerization (ROMP) was performed at 55 ° C. After 1 hour, analysis by gas chromatography (manufactured by Shimadzu Corporation, GC-14B; column: G-100, manufactured by Chemicals Inspection Association) confirmed the disappearance of cis-cyclooctene. Thereafter, 1.08 g (15.0 mmol) of ethyl vinyl ether was added, and the mixture was further stirred for 10 minutes.

  200 g of water was added to the obtained reaction solution, and the mixture was stirred at 40 ° C. for 30 minutes, and then allowed to stand at 40 ° C. for 1 hour for liquid separation, and then the aqueous layer was removed. To this was added 100 g of water again, and the mixture was stirred at 45 ° C. for 30 minutes, and then allowed to stand at 40 ° C. for 1 hour for liquid separation. Heptane is distilled off from the heptane layer under reduced pressure, and further dried in a vacuum dryer at 1 Pa and 100 ° C. for 6 hours, and the content of oligomer having a weight average molecular weight (Mw) of 142,000 and a molecular weight of 1000 or less is 9. 102.1 g (92% yield) of 2% polymer was obtained. The ratio of the carbon-carbon double bond in the side chain of this polymer (polyoctenylene) to the total carbon-carbon double bond was 0%.

[Acetone cleaning]
The obtained polymer was crushed to about 1 mm square, taken into a 500 ml separable flask equipped with a stirring base, a reflux tube and a thermometer, added with 300 g of acetone, and stirred at 40 ° C. for 3 hours. Acetone was removed by decantation, 300 g of acetone was added again, and the mixture was stirred at 40 ° C. for 3 hours. Acetone was removed by decantation, acetone was distilled off under reduced pressure, dried in a vacuum dryer at 1 Pa and 100 ° C. for 6 hours, weight average molecular weight (Mw) was 150,000, number average molecular weight was 37000, 99.0 g of a polymer (polyoctenylene (a-1)) having a molecular weight of 1000 or less and an oligomer content of 3.1% was obtained.

[Synthesis Example 2] Synthesis of compatibilizer (d-1):
The styrene-hydrogenated butadiene-styrene triblock copolymer was supplied to a unidirectional twin-screw extruder TEM-35B (manufactured by Toshiba Machine) at a rate of 7 kg / hour while the inlet was replaced with 1 L / min of nitrogen. The physical properties of the styrene-hydrogenated butadiene-styrene triblock copolymer are as follows: weight average molecular weight 100400, styrene / hydrogenated butadiene = 18/82 (mass ratio), 1,2-bond of butadiene units / 1,4-bond molar ratio = 47/53, hydrogenation rate of butadiene unit 97%, double bond amount 430 μeq / g, melt index 5 g / 10 min (230 ° C., 2160 g load), density 0.89 g / cm ³ . Next, a liquid mixture (TEAB / BBD = 29/71, mass ratio) of borane-triethylamine complex (TEAB) and boric acid 1,3-butanediol ester (BBD) is supplied from the liquid feeder 1 at a rate of 0.6 kg / hour. Then, 1,3-butanediol was supplied from the liquid feeder 2 at a rate of 0.4 kg / hr and continuously kneaded. During kneading, the pressure was adjusted so that the gauges of Vent 1 and Vent 2 showed about 20 mmHg. As a result, a triblock copolymer (d-1) containing a boronic acid 1,3-butanediol ester group (BBDE) was obtained from the discharge port at a rate of 7 kg / hour. The amount of boronic acid 1,3-butanediol ester groups in this copolymer was 210 μeq / g.

In addition, the structure and operating conditions of the twin screw extruder used for the reaction are as follows.
Screw diameter: 37mmφ
L / D: 52 (15 blocks)
Liquid feeder: C3 (liquid feeder 1), C11 (liquid feeder 2)
Vent position: C6 (vent 1), C14 (vent 2)
Screw configuration: Use temperature of seal ring between C5-C6, C10-C11, and C12. Temperature setting: C1 Water cooling
C2-C3 200 ° C
C4 to C15 250 ° C
Die 250 ℃
Screw rotation speed: 400rpm

[Preparation of oxygen-absorbing resin composition]
EVOH has an ethylene content of 38 mol%, a saponification degree of 99.5 mol%, an MFR of 3.4 g / min (210 ° C., 2160 g load), a melting point of 172 ° C., an oxygen transmission rate of 0.7 cc · 20 μm at 20 ° C. and 65% RH. / (M ² · day · atm) EVOH (hereinafter referred to as EVOH (b-1)) 91 parts by mass, the thermoplastic resin (A1) as the above polyoctenylene (a-1) 8 parts by mass, as a compatibilizing agent One part by weight of the above triblock copolymer (d-1) and 0.4242 parts by weight of cobalt stearate (II) (0.0400 parts by weight as cobalt atoms) were dry blended, and a 30 mmφ twin screw extruder (( Nippon Steel Works Co., Ltd. TEX-30SS-30CRW-2V), the inside of the cylinder was melt-kneaded while purging with nitrogen, pelletized, and EVOH (b- 1) an oxygen-absorbing resin composition (P) comprising polyoctenylene (a-1), a compatibilizing agent (d-1) and cobalt stearate (hereinafter referred to as oxygen-absorbing resin composition (p-1)) Pellets were obtained.

[Preparation and evaluation of film]
The above oxygen-absorbing resin composition (p-1) pellets were melt-extruded from a coat hanger die at 20 ° C. and 210 ° C. to obtain a film having a thickness of 20 μm.

The film obtained above was placed in a standard bottle with an internal volume of 260 ml filled with air at 23 ° C. and 50% RH (relative humidity). The air in the standard bottle contained 21:79 oxygen and nitrogen in a volume ratio. The mouth of the standard bottle was sealed with an epoxy resin using a multilayer sheet containing an aluminum layer, and then left at 20 ° C. After 14 days, the internal air was sampled with a syringe, and the oxygen concentration of the air was measured using gas chromatography. The amount of oxygen decrease was calculated from the volume ratio of oxygen and nitrogen obtained by measurement, and the oxygen absorption rate of the film at 23 ° C. and 50% RH was determined by using the following formula (II). 4.0 (cc / (m ² · day)).
E = F / (G × H × 2) (II)
here,
E: Oxygen absorption rate (cc / (m ² · day))
F: reduction amount of oxygen (cc),
G: Number of storage days (days) = 14 (days)
H: Surface area of the film sample (m ² )
Moreover, the surface area of the film sample was calculated | required from the following formula | equation (III).
H = I / (J × K) (III)
here,
I: Weight of film sample (g)
J: Sample thickness (μm) = 20
K: density of the film sample (g / cm ³ )

Further, when the time-dependent change in the OTR of the film was traced immediately after film formation, the zero OTR period (period in which the OTR value is zero (the detection limit is 0.1 or less)) in air is 63 days, which is excellent. Showed oxygen barrier properties. In addition, the measurement of OTR was carried out according to the method described in JIS K7126 (isobaric method) using MOCON OX-TRAN 2/20 type manufactured by Modern Control Co., Ltd. at 30 ° C. and 80% RH.
Here, the normal OTR is measured with respect to 1 atmosphere of oxygen partial pressure, but the above period is a zero OTR period converted to 1 atmosphere of air. That is, the value of the zero OTR period under air is a value obtained by dividing the zero OTR period measured by a normal method by 0.21 which is an oxygen partial pressure.

  Table 1 shows the evaluation results of the composition of the oxygen-absorbing resin composition, the oxygen absorption rate, and the like.

[Packaging preparation and storage test]
The oxygen-absorbing resin composition (p-1) pellets obtained above, the polypropylene resin (PP) and the adhesive resin (AD) are melt-kneaded with separate extruders, and three types are used using a co-extrusion device. A multilayer film consisting of 5 layers was formed. The thickness of each layer of the obtained film was PP / AD / oxygen-absorbing resin composition / AD / PP = 20/10/20/10/20 μm.

  A bag in which three sides were heat-sealed was prepared from the obtained multilayer film, and after food was put, the remaining one side was heat-sealed and sealed to package the food. Here, sausage, sheep gourd, and cut rice cake were used as food. In addition, air was slightly mixed in the package in which each food was packaged.

  The packaged body in which the obtained food was packaged was stored in air at 23 ° C. and 50% RH, and the flavor of the food after 5 days was confirmed. It was.

  Moreover, when the packaged body in which the obtained food was packaged was stored in air at 30 ° C. and 80% RH and the degree of discoloration and mold generation after 15 days was observed, all the foods were discolored and moldy. There was no outbreak.

  In addition, when the odor of the food after being stored in air at 30 ° C. and 80% RH for 15 days was confirmed, there was no odor transfer from the packaging material to the food, and the food was excellent as a packaging material. Was confirmed. Table 2 shows the composition of the packaging material and the results of the storage test.

[Preparation of oxygen-absorbing resin composition (P)]
EVOH has an ethylene content of 44 mol%, a saponification degree of 99.5 mol%, an MFR of 3.3 g / min (210 ° C., 2160 g load), a melting point of 165 ° C., an oxygen transmission rate of 1.9 cc · 20 μm at 20 ° C. and 65% RH. A resin composition (P) was prepared in the same manner as in Example 1 except that 91 parts by mass of EVOH (hereinafter referred to as EVOH (b-2)) of / (m ² · day · atm) was used ( Hereinafter, it is described as an oxygen-absorbing resin composition (p-2)).

[Preparation and evaluation of film]
A film was formed in the same manner as in Example 1 except that the oxygen-absorbing resin composition (p-2) was used instead of the oxygen-absorbing resin composition (p-1), and evaluation was performed in the same manner. The results are shown in Table 1.

[Packaging preparation and storage test]
A multilayer film was prepared in the same manner as in Example 1 except that the oxygen-absorbing resin composition (p-2) pellet was used instead of the oxygen-absorbing resin composition (p-1) pellet. went. The results are shown in Table 2.

[Preparation of oxygen-absorbing resin composition (P)]
EVOH has an ethylene content of 47 mol%, a saponification degree of 99.5 mol%, an MFR of 15 g / min (210 ° C., 2160 g load), a melting point of 159 ° C., an oxygen transmission rate of 3.8 cc · 20 μm / (20 ° C. and 65% RH). m ² · day · atm) EVOH (hereinafter referred to as EVOH (b-3)) 91 parts by mass was used in the same manner as in Example 1 except that the oxygen-absorbing resin composition (p-3) was used. Prepared.

[Preparation and evaluation of film]
A film was formed in the same manner as in Example 1 except that the oxygen-absorbing resin composition (p-3) was used in place of the oxygen-absorbing resin composition (p-1), and evaluation was performed in the same manner. . The results are shown in Table 1.

[Packaging preparation and storage test]
A multilayer film was prepared in the same manner as in Example 1 except that the oxygen-absorbing resin composition (p-3) pellets were used instead of the oxygen-absorbing resin composition (p-1) pellets, and evaluation was similarly performed. went. The results are shown in Table 2.

[Comparative Example 1]
[Preparation of oxygen-absorbing resin composition (P)]
EVOH has an ethylene content of 27 mol%, a saponification degree of 99.5 mol%, an MFR of 3.8 g / min (210 ° C., 2160 g load), a melting point of 190 ° C., an oxygen transmission rate of 0.1 cc · 20 μm at 20 ° C. and 65% RH. / (M ² · day · atm) EVOH (hereinafter referred to as EVOH (b-4)) 91 parts by weight, except that oxygen absorbing resin composition (p-4 ) Was prepared.

[Preparation and evaluation of film]
A film was formed in the same manner as in Example 1 except that the oxygen-absorbing resin composition (p-4) was used instead of the oxygen-absorbing resin composition (p-1), and evaluation was performed in the same manner. . The results are shown in Table 1.

[Packaging preparation and storage test]
A multilayer film was prepared in the same manner as in Example 1 except that the oxygen-absorbing resin composition (p-3) pellets were used instead of the oxygen-absorbing resin composition (p-1) pellets, and evaluation was similarly performed. went. The results are shown in Table 2.

[Comparative Example 2]
[Preparation of oxygen-absorbing resin composition (P)]
EVOH has an ethylene content of 32 mol%, a saponification degree of 99.5 mol%, an MFR of 3.7 g / min (210 ° C., 2160 g load), a melting point of 190 ° C., 20 ° C., and an oxygen transmission rate of 0.4 cc · 20 μm at 65% RH. / (M ² · day · atm) EVOH (hereinafter referred to as EVOH (b-5)) 91 parts by weight, except that oxygen absorbing resin composition (p-5 )

[Preparation and evaluation of film]
A film was formed in the same manner as in Example 1 except that the oxygen-absorbing resin composition (p-5) was used in place of the oxygen-absorbing resin composition (p-1), and evaluation was performed in the same manner. . The results are shown in Table 1.

[Packaging preparation and storage test]
A multilayer film was prepared in the same manner as in Example 1 except that the oxygen-absorbing resin composition (p-1) pellet was used instead of the oxygen-absorbing resin composition (p-1) pellet, and evaluation was similarly performed. went. The results are shown in Table 2.

[Comparative Example 3]
[Preparation and Evaluation of Film]
EVOH (b-2) was melt-extruded from a coat hanger die at 210 ° C. in a 20φ single-screw extruder to form a film having a thickness of 20 μm. Evaluation was performed in the same manner as in Example 1 except that the film thus obtained was used. The results are shown in Table 1.

[Packaging preparation and storage test]
EVOH (b-2), polypropylene resin (PP), and adhesive resin (AD) were melt-kneaded with separate extruders, and a multilayer film composed of three types and five layers was formed using a co-extrusion apparatus. The thickness of each layer of the obtained film was PP / AD / EVOH (b-2) / AD / PP = 20/10/20/10/20 μm. Evaluation was performed in the same manner as in Example 1 using the obtained multilayer film. The results are shown in Table 2.

[Comparative Example 4]
[Preparation of oxygen-absorbing resin composition (P)]
92 parts by mass of a polypropylene resin (PP) having an oxygen transmission rate of 2000 cc · 20 μm / (m ² · day · atm) at 20 ° C. and 65% RH, and 8 masses of the above polyoctenylene (a-1) as the thermoplastic resin (A1). Parts, and 0.4242 parts by mass of cobalt stearate (II) (0.0400 parts by mass as cobalt atoms) were melt-kneaded and pelletized in the same manner as in Example 1 to obtain an oxygen-absorbing resin composition ( P) (hereinafter referred to as oxygen-absorbing resin composition (p-6)) was obtained.

[Preparation and evaluation of film]
A film was formed in the same manner as in Example 1 except that the oxygen-absorbing resin composition (p-6) was used in place of the oxygen-absorbing resin composition (p-1), and evaluation was performed in the same manner. . The results are shown in Table 1.

[Packaging preparation and storage test]
The oxygen-absorbing resin composition (p-6) pellets and polypropylene resin (PP) were melt-kneaded with separate extruders, and a multilayer film composed of two types and three layers was formed using a co-extrusion apparatus. The thickness of each layer of the obtained film was PP / oxygen-absorbing resin composition / PP = 20/20/20 μm. Evaluation was performed in the same manner as in Example 1 using the obtained multilayer film. The results are shown in Table 2.

[Comparative Example 5]
[Packaging preparation and storage test]
The oxygen-absorbing resin composition (p-6), EVOH (b-2), polypropylene resin (PP), and adhesive resin (AD) are melt-kneaded with separate extruders, and 4 using a co-extrusion device. A multilayer film composed of 6 seed layers was formed. The thickness of each layer of the obtained film was PP / AD / EVOH (b-2) / AD / oxygen-absorbing resin composition / PP = 20/10/20/10/20/20 μm. Evaluation was performed in the same manner as in Example 1 using the obtained multilayer film. The results are shown in Table 2.

[Comparative Example 6]
[Preparation of oxygen-absorbing resin composition (P)]
Comparative Example 4 except that a low density polyethylene resin (LDPE) having an oxygen transmission rate of 10000 cc · 20 μm / (m ² · day · atm) at 20 ° C. and 65% RH was used instead of the polypropylene resin (PP). Similarly, an oxygen-absorbing resin composition (p-7) was obtained.

[Preparation and evaluation of film]
A film was formed in the same manner as in Example 1 except that the oxygen-absorbing resin composition (p-7) was used in place of the oxygen-absorbing resin composition (p-1), and evaluation was performed in the same manner. . The results are shown in Table 1.

[Packaging preparation and storage test]
The oxygen-absorbing resin composition (p-7) pellets, EVOH (b-2), polypropylene resin (PP) and adhesive resin (AD) are melt-kneaded with separate extruders, using a co-extrusion device, A multilayer film composed of 4 types and 6 layers was formed. The thickness of each layer of the obtained film was PP / AD / EVOH (b-2) / AD / oxygen-absorbing resin composition / PP = 20/10/20/10/20/20 μm. Evaluation was performed in the same manner as in Example 1 using the obtained multilayer film. The results are shown in Table 2.

  In Table 1, the resin composition of Comparative Example 3 does not show oxygen absorbability, but for convenience, it is described in the same row as other oxygen-absorbing resins (P). Moreover, when other resin was used instead of EVOH (B), this other resin was described in the EVOH (B) column.

Abbreviations such as resins and resin compositions in Table 2 are the same as those used in the above examples.

  Since the packaging material of the present invention has a high oxygen absorption and the generation and movement of odorous substances accompanying oxidation is at a very low level, food with particular emphasis on flavor and pet food for animals with sensitive taste It is suitably used as a packaging material.

Claims (12)

A package comprising an oxygen-absorbing layer comprising an oxygen-absorbing resin composition (P) comprising an ethylene-vinyl alcohol copolymer (B) and a resin (A1) containing a carbon-carbon double bond substantially only in the main chain. A packaging material, wherein the oxygen absorption rate of the oxygen absorption layer at 23 ° C. and 50% RH is 2.0 cc / (m ² · day) or more. The packaging material according to claim 1, wherein the thermoplastic resin (A1) having a carbon-carbon double bond substantially only in the main chain is polyoctenylene. The packaging material according to claim 1 or 2, wherein the oxygen-absorbing resin composition (P) further contains a transition metal salt (C1). The packaging material according to claim 3, wherein the transition metal salt (C1) is at least one metal salt selected from the group consisting of iron salt, nickel salt, copper salt, manganese salt and cobalt salt. The ethylene-vinyl alcohol copolymer (B) is an ethylene-vinyl alcohol copolymer having an ethylene content of 33 to 46 mol% and a saponification degree of 90% or more. Packaging material. The packaging material according to any one of claims 1 to 5, wherein the oxygen-absorbing resin composition (P) further contains a compatibilizer (D). The packaging material according to any one of claims 1 to 6, wherein the packaging material is a multilayer structure. The packaging material according to any one of claims 1 to 6, wherein the packaging material is a multilayer container. The packaging material according to any one of claims 1 to 6, wherein the packaging material is a multilayer pouch. The packaging material according to any one of claims 1 to 6, wherein the packaging material is a lid material. The package body which packaged the foodstuff with the packaging material for any one of Claims 1-10. The package body which packaged pet food with the packaging material in any one of Claims 1-10.