JP4941873B2 - Oxygen-absorbing resin composition - Google Patents

Description

  The present invention relates to an oxygen-absorbing resin composition with less oxidation by-products used in packaging materials such as beverages, foods, and pharmaceuticals, which are susceptible to deterioration in the presence of oxygen.

In recent years, various plastic containers have been used as packaging containers because they have advantages such as light weight, transparency and easy moldability.
A plastic container is inferior in oxygen barrier property to a metal container or a glass container, so that deterioration of the contents filled in the container or a decrease in flavor becomes a problem.
In order to prevent this, the plastic container has a multilayered structure, and at least one layer is provided with a layer of a resin excellent in oxygen barrier properties, for example, an ethylene-vinyl alcohol copolymer. In addition, there is a container provided with an oxygen absorption layer in order to remove oxygen remaining inside the container and oxygen entering from the outside of the container. Examples of the oxygen absorbent (deoxygenating agent) used in the oxygen absorbing layer include those containing a reducing substance such as iron powder as a main ingredient (for example, see Patent Document 1), and transitions with ethylenically unsaturated hydrocarbons. Some use an oxygen scavenger comprising a metal catalyst (see, for example, Patent Documents 2 to 4).

  However, the method of blending an oxygen absorbent such as iron powder into a resin and using it for the container wall of a packaging material is satisfactory in that the oxygen absorption performance is large, but the resin is colored in a unique hue. In addition, there is a limitation in application that it cannot be used in the field of packaging that requires transparency. In addition, in the method using an oxygen scavenger composed of an ethylenically unsaturated hydrocarbon and a transition metal catalyst, the ethylenically unsaturated hydrocarbon itself absorbs oxygen and achieves an oxygen barrier property. However, when the blending amount is increased, there arises a problem that moldability and transparency are lowered. For this reason, since the period in which oxygen can be effectively absorbed is limited, it cannot be said that it sufficiently corresponds to the demand for long-term storage. Furthermore, coloring and odor are caused by oxygen absorption.

  In order to solve these problems, the present inventors have made a polyolefin resin (A) obtained by polymerizing an olefin having 2 to 8 carbon atoms into a resin other than the resin (A) and the oxidation of the resin (A). In a resin composition containing a specific amount of the resin (B) serving as a trigger and the transition metal catalyst (C), the resin (B) acts as an oxidation trigger for the polyolefin resin (A) and the polyolefin resin (A) is oxygen. It was found that the amount of oxygen absorbed in the resin composition can be significantly improved (PCT / JP03 / 10657).

Japanese Examined Patent Publication No. 62-1824 JP 2001-39475 A Japanese Patent Laid-Open No. 5-115776 Japanese translation of PCT publication No. 8-502306

However, the amount of oxidation by-products generated by oxygen absorption is still large, and depending on the contents, there are those that feel a nasty taste and odor. In addition, there is a problem that embrittlement of PE proceeds due to oxidation.
An object of the present invention is to provide an oxygen-absorbing resin composition that has fewer oxidation by-products, can maintain practical mechanical strength even when oxidation proceeds, and is excellent in oxygen-absorbing performance.

  Linear low density polyethylene resin (A), which is a resin other than resin (A) and contains resin (B) that triggers oxidation of resin (A), and resin (B) is in the matrix of resin (A) In the resin composition in which the oxidation reaction of the matrix resin (A) proceeds and absorbs oxygen when it comes into contact with oxygen, the resin (A) has a side chain of 0.003 eq / g or less. Provided is an oxygen-absorbing resin composition, which is a resin comprising a linear hydrocarbon.

The oxygen-absorbing resin composition of the present invention comprises a linear low density polyethylene resin (A) comprising a linear hydrocarbon having a side chain of 0.003 eq / g or less and a resin (B) other than the resin (A). The resin (B) is triggered by the resin (B) and the oxidation of the resin (A) proceeds.
The resin (A) is particularly preferably polymerized using a single site catalyst. For example, a copolymer of ethylene and butene, a copolymer of ethylene and pentene using a metallocene catalyst as a polymerization catalyst, ethylene, Preferred are linear low-density polyethylenes such as copolymers of hexene and octene, and copolymers of ethylene and octene (see, for example, “Creation of New Generation Polymers and Metallocene Catalysts” edited by Kazuo Soga CMC, 1993). These resins may be used alone or in combination of two or more.
In the resin (A), the the low density 0.88~0.94g / cm ^3, preferably 0.90~0.93g / cm ^3. The straight chain length of the branch site of the resin (A) is preferably C _1-6 , more preferably C _1-4 , and most preferably C ₄ . The ratio of the branch site is preferably 0.001 to 0.003 eq / g.
In a conventional oxygen absorbent, for example, an oxygen scavenger comprising an ethylenically unsaturated hydrocarbon and a transition metal catalyst disclosed in JP-A-5-115777, the number of unsaturated bonds of the ethylenically unsaturated hydrocarbon Determines the amount of oxygen absorbed. In general, the oxygen scavenger is used by blending with other thermoplastic resins depending on the application. However, if the amount of the oxygen scavenger is increased, the durability and moldability are lowered, and the transparency is also lowered. Problem arises. Therefore, the blending amount is limited, and the oxygen absorption amount of the resin composition is limited.

In the oxygen-absorbing resin composition of the present invention, the resin (B) is preferably present in a dispersed state in the matrix of the resin (A). The resin (B) is preferably dispersed in the form of fine particles having an average particle diameter of 10 μm or less, and particularly preferably dispersed in the form of fine particles of 5 μm or less. The resin (A) itself functions as an oxygen absorbent by the trigger action of the resin (B) uniformly dispersed in the matrix of the resin (A). That is, the oxygen-absorbing resin composition of the present invention can absorb much more oxygen than the conventional oxygen scavenger because the matrix resin itself absorbs oxygen. Therefore, the resin composition of the present invention can absorb oxygen more effectively over a longer period than conventional oxygen scavengers. Moreover, the compounding quantity of resin (B) is a small quantity of compounding so that a trigger effect | action may express, and the fall of the moldability of matrix resin (A) does not arise. In addition, the general-purpose resin can absorb oxygen, which is advantageous in terms of cost.
The resin (A) is preferably contained in a large proportion so that a matrix can be formed and a large amount of oxygen can be absorbed by oxidation. The content of the resin (A) is 90 to The range of 99% by weight is more preferable, and the range of 92.5 to 97.5% by weight is more preferable. Further, the resin (B) can exist in a dispersed state in the matrix of the resin (A), and can sufficiently function as a trigger for oxidation of the resin (A). The content of the resin (B) is preferably in the range of 1 to 10% by weight in consideration of moldability when forming a film, sheet or cup, tray, bottle, tube or cap. The range of 2.5 to 7.5% by weight is more preferable.

Resin (B) is a resin other than resin (A), and is a resin that triggers oxidation of resin (A). The resin (B) is preferably a resin having a carbon-hydrogen bond that is more likely to withdraw hydrogen than the methylene chain. For example, a resin having a carbon-carbon double bond in the main chain or side chain, and a tertiary carbon atom in the main chain. And a resin having an active methylene group in the main chain and a resin having an aldehyde group.
These may be contained alone in the resin (A), or may be contained in a combination of two or more.
Examples of the resin (B) having a carbon-carbon double bond in the main chain or side chain include resins containing units derived from a linear or cyclic conjugated or non-conjugated polyene.
Examples of such monomers include conjugated dienes such as butadiene and isoprene; 1,4-hexadiene, 3-methyl-1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1, Chain non-conjugated dienes such as 4-hexadiene, 4,5-dimethyl-1,4-hexadiene, 7-methyl-1,6-octadiene; methyltetrahydroindene, 5-ethylidene-2-norbornene, 5-methylene-2 Cyclic non-conjugated dienes such as norbornene, 5-isopropylidene-2-norbornene, 5-vinylidene-2-norbornene, 6-chloromethyl-5-isopropenyl-2-norbornene, dicyclopentadiene; 2,3-diisopropyl Liden-5-norbornene, 2-ethylidene-3-isopropylidene-5-norbornene, 2-propene Triene such as Le-2,2-norbornadiene and the like.
Specific examples of the polymer include polybutadiene, polyisoprene, ethylene-propylene-diene copolymer, polyterpene, and dicyclopentadiene resin.

From the viewpoint of the trigger effect, a resin having a tertiary carbon at the allylic position is preferable, and among them, a resin having a cyclic alkene structure having a tertiary carbon at the allylic position in the molecule is preferable in that there are few oxidation byproducts.
The resin (B) containing a tertiary carbon atom in the main chain has a polymer or copolymer containing a unit derived from an α-olefin having 3 to 20 carbon atoms, or has a benzene ring in the side chain. A polymer or copolymer is preferably used. Specific examples of the α-olefin include propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-nonadecene, 1-eicosene, 9-methyl-1-decene, 11-methyl-1- Examples include dodecene and 12-ethyl-1-tetradecene. Specific polymers include, in particular, polypropylene, poly-1-butene, poly-1-hexene, poly-1-octene, ethylene-propylene copolymer, ethylene-butene-1 copolymer, and ethylene-propylene-1. -Butene copolymer is mentioned. Examples of the monomer having a benzene ring in the side chain include alkenylbenzene such as styrene, 3-phenylpropene, 2-phenyl-2-butene. Specific examples of the polymer include polystyrene or a styrene copolymer, a styrene-butadiene copolymer, and a styrene-isoprene copolymer.
The resin (B) having an active methylene group in the main chain is a resin having an electron-withdrawing group, particularly a carbonyl group and an adjacent methylene group in the main chain. Specifically, carbon monoxide and Examples include copolymers with olefins, particularly carbon monoxide-ethylene copolymers.
Further, the aldehyde group-containing resin is a radical polymerized monomer using acrolein or methacrolein, and a copolymer with styrene is also preferably used.

As the resin (B), a polystyrene or styrene copolymer having a benzene ring in the side chain is particularly preferable from the viewpoint of a function as a trigger for oxidation of the resin (A).
Of the styrene copolymers, those containing 10% by weight or more of styrene are preferable from the viewpoint of radical generation efficiency, those containing 10 to 70% by weight of styrene are more preferable, and those containing 10 to 67% by weight of styrene. More preferred are:
The styrene copolymer preferably has a site derived from a diene from the viewpoint of the trigger effect. The diene-derived portion preferably contains an isoprene unit or a butadiene unit, and particularly preferably a styrene-isoprene copolymer or styrene-butadiene copolymer, which is a copolymer of styrene and isoprene or butadiene. The copolymer may be a random copolymer or a block copolymer, but the block copolymer is more preferable in terms of trigger effect, and in particular, a styrene-isoprene block copolymer having a styrene block at the molecular end portion. A styrene-butadiene block copolymer is preferred. In particular, a styrene-isoprene-styrene triblock copolymer and a styrene-butadiene-styrene triblock copolymer are preferable. The triblock copolymer may be linear or radial in terms of chemical structure.
A copolymer in which a diene-derived portion of the styrene copolymer having a diene-derived portion is appropriately hydrogenated is particularly preferable because deterioration and coloring during molding can be suppressed. The diene-derived site is preferably an isoprene unit or a butadiene unit, and in particular, a hydrogenated styrene-isoprene copolymer or a hydrogenated styrene-butadiene copolymer, which is a hydrogenated product of a copolymer of styrene and isoprene or butadiene. Coalescence is preferred. The copolymer may be a random copolymer or a block copolymer, but the block copolymer is more preferable in terms of trigger effect, and in particular, a styrene-isoprene block copolymer having a styrene block at the molecular end portion. The styrene-butadiene block copolymer is preferable, and the hydrogenated styrene-isoprene-styrene triblock copolymer and the hydrogenated styrene-butadiene-styrene triblock copolymer are more preferable. The chemical structure of the triblock copolymer may be linear or radial, and the carbon-carbon double bond at the diene site before hydrogenation may be present in the main chain in the form of a vinylene group. It may be present in the side chain in the form of a vinyl group. Examples of the random copolymer include hydrogenated styrene-isoprene random copolymer or hydrogenated styrene-butadiene random copolymer.
Further, as another embodiment of the styrene copolymer in which the site derived from the diene is appropriately hydrogenated, a hydrogenated styrene-diene-olefin crystal triblock copolymer is also useful, in particular, a hydrogenated styrene-butadiene-olefin crystal. Triblock copolymers are preferred in that oxidation byproducts are suppressed.

Further, in the resin having a carbon-carbon double bond in the main chain or side chain listed as the resin (B), a resin having a tertiary carbon atom in the main chain, and a resin having an active methylene group in the main chain, From the viewpoint of thermal stability during molding and function as a trigger for oxidation of the resin (A), the resin (B) is preferably a resin that does not contain an excessive carbon-carbon double bond. Note that the carbon-carbon bond of the benzene ring is not called a carbon-carbon double bond.
If the carbon-carbon double bond is present in excess, the oxygen-absorbing resin composition of the present invention tends to inhibit the oxidation of the resin (A). Moreover, it becomes a cause of coloring of the oxygen-absorbing resin composition during molding.
The molecular weight of the resin (B) is not particularly limited, but the number average molecular weight is preferably in the range of 1,000 to 500,000, more preferably in the range of 10,000 to 250,000 from the viewpoint of dispersibility in the resin (A). It is.

Next, the transition metal catalyst (C) used in the present invention includes Group VIII metal components such as iron, cobalt and nickel, Group I metals such as copper and silver, tin, titanium, zirconium and the like. Mention may be made of Group IV metals, Group V of vanadium, Group VI such as chromium, and Group VII metals such as manganese. Preferably, it is a metal component of Group VIII of the periodic table such as iron, cobalt, nickel, etc. In particular, the cobalt component is preferable because of its high oxygen absorption rate.
The transition metal catalyst (C) is used in the form of a low-valent inorganic acid salt, organic acid salt or complex salt of the transition metal.
Examples of inorganic acid salts include halides such as chlorides, sulfur oxyacid salts such as sulfates, nitrogen oxyacid salts such as nitrates, phosphorus oxyacid salts such as phosphates, and silicates.
Examples of the organic acid salt include carboxylate, sulfonate, phosphonate, and the like, and carboxylate is preferable. Specific examples thereof include acetic acid, propionic acid, isopropionic acid, butanoic acid, isobutanoic acid, Pentanoic acid, isopentanoic acid, hexanoic acid, heptanoic acid, isoheptanoic acid, octanoic acid, 2-ethylhexanoic acid, nonanoic acid, 3,5,5-trimethylhexanoic acid, decanoic acid, neodecanoic acid, undecanoic acid, lauric acid, myristic Transition metals such as acid, palmitic acid, margaric acid, stearic acid, arachidic acid, Linderic acid, tuzuic acid, petroceric acid, oleic acid, linoleic acid, linolenic acid, arachidonic acid, formic acid, oxalic acid, sulfamic acid, naphthenic acid Salt.
As the transition metal complex, a complex with β-diketone or β-keto acid ester is used. Examples of β-diketone or β-keto acid ester include acetylacetone, ethyl acetoacetate, 1,3-cyclohexadione. , Methylenebis-1,3-cyclohexadione, 2-benzyl-1,3-cyclohexadione, acetyltetralone, palmitoyltetralone, stearoyltetralone, benzoyltetralone, 2-acetylcyclohexanone, 2-benzoylcyclohexanone, 2 -Acetyl-1,3-cyclohexanedione, benzoyl-p-chlorobenzoylmethane, bis (4-methylbenzoyl) methane, bis (2-hydroxybenzoyl) methane, benzoylacetone, tribenzoylmethane, diacetylbenzoylmethane, stearo Rubenzoylmethane, palmitoylbenzoylmethane, lauroylbenzoylmethane, dibenzoylmethane, bis (4-chlorobenzoyl) methane, bis (methylene-3,4-dioxybenzoyl) methane, benzoylacetylphenylmethane, stearoyl (4-methoxybenzoyl) ) Methane, butanoylacetone, distearoylmethane, acetylacetone, stearoylacetone, bis (cyclohexanoyl) -methane, dipivaloylmethane, and the like can be used. In the present invention, the transition metal catalyst (C) can be used alone or in combination of two or more.

The transition metal catalyst (C) is preferably present at least in the resin (A), can promote the progress of the oxidation reaction of the resin (A), and can efficiently absorb oxygen. More preferably, the transition metal catalyst (C) can be present in the resin (A) and the resin (B) to promote the trigger function of the resin (B). Moreover, the compounding quantity of a transition metal catalyst (C) should just be the quantity which can advance the oxidation reaction of resin (A) according to the characteristic of the transition metal catalyst to be used, and fully accelerates the oxidation reaction of resin (A). And from the point of prevention of the moldability fall by deterioration of a fluid characteristic, generally the range of 10-3000 ppm is preferable, and the range of 50-1000 ppm is more preferable.
Although not all of the oxygen absorption mechanism of the oxygen-absorbing resin composition of the present invention has been elucidated, it is presumed as follows by the study of the present inventors.
In the oxygen-absorbing resin composition of the present invention, hydrogen is first extracted from the trigger resin (B) by the transition metal catalyst (C) to generate radicals. Subsequently, the attack by the radicals and the transition metal catalyst ( C) caused hydrogen abstraction of the matrix resin (A), radicals were also generated in the matrix resin (A), and oxygen contacted the matrix resin (A) in the presence of the radicals thus generated. It is thought that sometimes the initial oxidation of the matrix resin (A) occurs. Thereafter, the oxidation reaction of the matrix resin (A) proceeds in a chain according to the autoxidation theory by the action of the transition metal catalyst. In the expression of the trigger effect, the presence of a benzyl group is extremely important. In a styrene-based copolymer containing a benzyl group, the benzyl carbon has a lower CH bond dissociation energy than other CH bonds. It is considered that radicals are generated first and the triggering action is effectively expressed.
About the manufacturing method of the oxygen absorptive resin composition of this invention, about mixing of the said component (A)-(C), you may mix these three components separately, Moreover, two components are mixed among the said three components. You may mix beforehand and this and the remaining component may be mixed. For example, a method in which the resin (A) and the resin (B) are mixed in advance and the transition metal catalyst (C) is mixed therewith, or the resin (A) and the transition metal catalyst (C) are mixed in advance, A method of mixing the resin (B), or a method of mixing the resin (B) and the transition metal catalyst (C) in advance and mixing the resin (A) with this may be mentioned.
In order to mix the transition metal catalyst (C) with the resin (A) and / or the resin (B), various means can be used. For example, a method in which the transition metal catalyst (C) is dry-blended with a resin, or the transition metal catalyst (C) is dissolved in an organic solvent, and this solution is mixed with a powder or granular resin. There is a method of drying in an inert atmosphere. Since the transition metal catalyst (C) is a small amount compared to the resin, the transition metal catalyst (C) is dissolved in an organic solvent, and this solution is mixed with the powdered or granular resin in order to perform blending uniformly. The method is preferred.
Solvents for dissolving the transition metal catalyst (C) include alcohol solvents such as methanol, ethanol and butanol, ether solvents such as dimethyl ether, diethyl ether, methyl ethyl ether, tetrahydrofuran and dioxane, and ketone solvents such as methyl ethyl ketone and cyclohexanone. , Hydrocarbon solvents such as n-hexane and cyclohexane can be used. The concentration of the transition metal catalyst (C) is preferably 5 to 90% by weight.
It is also possible to prepare a master batch of a resin containing a transition metal catalyst at a relatively high concentration and dry-blend it with an unblended resin.
When mixing the resin (A) and the resin (B), or when mixing the resin (A), the resin (B) and the transition metal catalyst (C), and when storing the mixed composition, use it before use. It is preferable to carry out in a non-oxidizing atmosphere so that the composition does not oxidize. That is, mixing or storage is preferably performed under reduced pressure or in a nitrogen stream.

Various additives such as a radical initiator and a photosensitizer can be blended in the oxygen-absorbing resin composition of the present invention.
Examples of the radical initiator and photosensitizer include benzoin such as benzoin, benzoin methyl ether, benzoin ethyl ether, and benzoin isopropyl ether and alkyl ethers thereof; acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2- Diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propane-1 Acetophenones such as -one; anthraquinones such as 2-methylanthraquinone and 2-amylanthraquinone; 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthate In general, thioxanthones such as 2,4-diisopropylthioxanthone, ketals such as acetophenone dimethyl ketal and benzyl dimethyl ketal; benzophenones such as benzophenone or xanthones, generally known photoinitiators are used. Such photoradical initiators can be used in combination with one or more known and commonly used photopolymerization accelerators such as benzoic acid type or tertiary amine type.
Other additives include fillers, colorants, heat stabilizers, weathering stabilizers, antioxidants, anti-aging agents, light stabilizers, UV absorbers, antistatic agents, lubricants such as metal soap and wax, An additive such as a quality resin or rubber may be mentioned, and it can be added according to a formulation known per se. For example, by incorporating a lubricant, the bite of the resin into the screw is improved. Lubricants include metal soaps such as magnesium stearate and calcium stearate, hydrocarbons such as fluid, natural or synthetic paraffin, micro wax, polyethylene wax and chlorinated polyethylene wax, and fatty acids such as stearic acid and lauric acid. , Stearic acid amide, valmitic acid amide, oleic acid amide, esylic acid amide, fatty acid monoamide type or bisamide type such as ethylene bisstearamide, butyl stearate, hydrogenated castor oil, ethylene glycol mono An ester type such as stearate and a mixture thereof are generally used, and the addition amount of the lubricant is suitably in the range of 50 to 1000 ppm per polyamide.

The oxygen-absorbing composition of the present invention can be used for oxygen absorption in a sealed package in the form of powder, granules or sheets. Moreover, it can mix | blend with resin and rubber | gum for liners, gaskets, or coating formation, and can be used for residual oxygen absorption in a package. Furthermore, it can be used for the production of a package as a packaging material in the form of a film or sheet, or as a packaging container in the form of a cup, tray, bottle, tube container or the like.
The oxygen-absorbing resin composition of the present invention is preferably used in the form of a laminate composed of at least one layer containing it and another resin layer.

The laminate of the present invention has at least one layer containing the above oxygen-absorbing resin composition (hereinafter referred to as an oxygen-absorbing layer). The layer containing the oxygen-absorbing resin composition is both a layer made of only the above-described oxygen-absorbing resin composition and a layer formed by blending the oxygen-absorbing resin composition with another resin as a base material. Including the case.
The resin layer other than the oxygen absorbing layer constituting the laminate can be appropriately selected from a thermoplastic resin or a thermosetting resin depending on its use mode or required function. For example, an olefin resin, a thermoplastic polyester resin, an oxygen barrier resin, and the like can be given.
As the olefin resin, low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), linear low density polyethylene (LLDPE), linear ultra low density polyethylene (LVLDPE), polypropylene (PP) , Ethylene-propylene copolymer, polybutene-1, ethylene-butene-1 copolymer, propylene-butene-1 copolymer, ethylene-propylene-butene-1 copolymer, ethylene-vinyl acetate copolymer, ion Cross-linked olefin copolymers (ionomers) or blends thereof may be mentioned.
Examples of the thermoplastic polyester resin include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), copolymerized polyesters thereof, and blends thereof.
Examples of the oxygen barrier resin include an ethylene-vinyl alcohol copolymer (EVOH). For example, an ethylene-vinyl acetate copolymer having an ethylene content of 20 to 60 mol%, preferably 25 to 50 mol%, has a saponification degree of 96 mol% or more, preferably 99 mol% or more. A saponified copolymer obtained by saponification is used.
This saponified ethylene vinyl alcohol copolymer has a molecular weight capable of forming a film. Generally, it has a viscosity of 0.01 dl / g or more, preferably 0.05 dl / g or more, measured at 30 ° C. in a mixed solvent of phenol: water in a weight ratio of 85:15.
As another example of the oxygen barrier resin, a polyamide resin such as polymetaxylidene adipamide (MXD6), a polyester resin such as polyglycolic acid, or the like can be used.

The structure of the laminate of the present invention can be appropriately selected depending on the use mode and the required function. For example, the oxygen absorption layer is expressed as OAR and has the following structure.
Two-layer structure: PET / OAR, PE / OAR, OPP / OAR,
Three-layer structure: PE / OAR / PET, PET / OAR / PET, PE / OAR / OPP, EVOH / OAR / PET, PE / OAR / COC,
Four-layer structure: PE / PET / OAR / PET, PE / OAR / EVOH / PET, PET / OAR / EVOH / PET, PE / OAR / EVOH / COC, PE / OAR / EVOH / PE,
Five-layer structure: PET / OAR / PET / OAR / PET, PE / PET / OAR / EVOH / PET, PET / OAR / EVOH / COC / PET, PET / OAR / PET / COC / PET, PE / OAR / EVOH / COC / PET, PE / EVOH / OAR / EVOH / PE, PP / EVOH / OAR / EVOH / PP, PE / EVOH / OAR / COC / PE
Six-layer structure: PET / OAR / PET / OAR / EVOH / PET, PE / PET / OAR / COC / EVOH / PET, PET / OAR / EVOH / PET / COC / PET, PE / EVOH / OAR / PE / EVOH / PE, PP / EVOH / OAR / PP / EVOH / PP, PE / EVOH / OAR / REG / EVOH / PE, PE / EVOH / OAR / REG / EVOH / PP, PP / EVOH / OAR / REG / EVOH / PP, PE / EVOH / OAR / EVOH / COC / PE
Seven-layer structure: PET / OAR / COC / PET / EVOH / OAR / PET, PE / REG / EVOH / OAR / EVOH / COC / PE, PE / EVOH / OAR / REG / EVOH / COC / PE, PP / EVOH / OAR / REG / EVOH / COC / PP
PE means low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), linear low density polyethylene (LLDPE), and linear ultra-low density polyethylene (LVLDPE). REG means a resin composition containing scraps and the like generated in the process of forming the laminate of the present invention.
In these structures, a structure having at least one oxygen barrier layer is preferable because the life of the oxygen absorbing layer can be improved.
If necessary, an adhesive resin can be interposed between the resin layers in the laminate. As such an adhesive resin, a carboxylic acid, a carboxylic acid anhydride, and a carboxylic acid as a main chain or a side chain, 1 to 700 milliequivalent (meq) / 100 g resin, preferably 10 to 500 meq / 100 g resin, The polymer contained at a concentration of

Examples of the adhesive resin include ethylene-acrylic acid copolymer, ion-crosslinked olefin copolymer, maleic anhydride grafted polyethylene, maleic anhydride grafted polypropylene, acrylic acid grafted polyolefin, ethylene-vinyl acetate copolymer, and copolymerization. There are polyester, copolymer polyamide, etc., and a combination of two or more of these may be used.
These adhesive resins are useful for lamination by coextrusion or sandwich lamination. In addition, an isocyanate-based or epoxy-based thermosetting adhesive resin is also used for adhesive lamination of a gas barrier resin film and a moisture-resistant resin film that are formed in advance.
In the laminate using the oxygen-absorbing resin composition of the present invention, any of the above-mentioned layers, particularly a layer located on the inner layer side from the oxygen-absorbing material layer, is used for capturing by-products generated during oxygen absorption. It is preferable to use a deodorizing agent or an adsorbent of oxidation by-products.
As these deodorizing agents or adsorbents, those known per se, such as natural zeolite, synthetic zeolite, silica gel, activated carbon, impregnated activated carbon, activated clay, activated aluminum oxide, clay, diatomaceous earth, kaolin, talc, bentonite, sepiolite, attapulgite Magnesium oxide, iron oxide, aluminum hydroxide, magnesium hydroxide, iron hydroxide, magnesium silicate, aluminum silicate, synthetic hydrotalcite, and amine-supported porous silica can be used. Among them, the amine-supporting porous silica is preferable in terms of reactivity with the aldehyde which is an oxidation by-product, and also exhibits excellent adsorptivity to various oxidation by-products and is transparent in terms of transparency. So-called high silica zeolite having a large alumina ratio is preferred.

For the production of the laminate, a coextrusion method known per se can be used. For example, a laminate can be formed by performing extrusion molding using a multilayer multiple die using the number of extruders corresponding to the type of resin.
Thereby, laminates, such as a film, a sheet, a bottle, a cup, a cap, a tube, a tube forming parison or pipe, a bottle or tube forming preform, can be formed.
Packaging materials such as films can be used as packaging bags of various forms. For example, ordinary pouches with three- or four-side seals, gusseted pouches, standing pouches, pillow packaging bags, and the like can be given. Bag making can be performed by a known bag making method.
A bottle can be easily formed by pinching off the parison with a pair of split molds and blowing a fluid such as air into the interior. Moreover, after cooling a pipe and a preform, it is heated to a stretching temperature, stretched in the axial direction, and blow stretched in the circumferential direction by fluid pressure to obtain a stretch blow bottle or the like.
Furthermore, a packaging container such as a cup shape or a tray shape can be obtained by subjecting the film or sheet to means such as vacuum forming, pressure forming, bulging forming, or plug assist forming.
For the production of a multilayer injection molded article, a multilayer injection molded article can be produced by a co-injection method or a sequential injection method using a number of injection molding machines corresponding to the type of resin.
Furthermore, for the production of a multilayer film or a multilayer sheet, an extrusion coating method or sandwich lamination can be used, and a multilayer film or sheet can also be produced by dry lamination of a film formed in advance.
Since the laminated body of this invention interrupts | blocks oxygen effectively, it can be preferably used for a packaging material or a packaging container. Since this laminated body can absorb oxygen for a long period of time, it is useful as a container that prevents a decrease in the flavor of the contents and improves the shelf life.
In particular, content that easily deteriorates in the presence of oxygen, such as beer, wine, fruit juice, carbonated soft drink, etc. for beverages, fruits, nuts, vegetables, meat products, infant foods, coffee, jam, mayonnaise, ketchup It is useful for packaging materials such as edible oils, dressings, sauces, boiled foods, dairy products, etc., and other medicines, cosmetics, hair dyes and the like.
Examples of the present invention will be described below, but the present invention is not limited thereto.

[Structural analysis of base resin]
0.2 g of low density polyethylene resin was cooled for 10 minutes with a freeze pulverizer (JFC-300: Nippon Analytical Industrial Co., Ltd.) and then pulverized for 10 minutes. Next, 0.6 ml of a mixed solvent of benzene / orthodichlorobenzene = 1/3 deuterated compound was added to 0.06 g of the obtained pellets and sealed, and ¹³ C-NMR (EX-270: JEOL ( Co.)) measurement. From this measurement result, the number of branches and the number of carbons in the side chain contained in the main chain skeleton of the low density polyethylene resin were determined. In addition, a base resin having a side chain of 0.003 eq / g or less of a straight-chain hydrocarbon was marked with ◯, and the others were marked with ×.
[Evaluation of oxygen absorption performance]
The oxygen-absorbing resin composition was cooled for 10 minutes with a freeze pulverizer (JFC-300: Nippon Analytical Industrial Co., Ltd.) and then pulverized for 10 minutes. Next, 0.1 g of the obtained sample and 1 cc of distilled water were put into a sealed container having an internal volume of 85 cc, and sealed with a lid material using an aluminum foil as a barrier layer. After aging for 2 weeks under conditions of 30 ° C., the oxygen concentration in the container was measured by gas chromatography (GC-3BT: Shimadzu Corporation). A sample having an oxygen absorption of 5 cc or more per 1 g of the sample was marked with ◯, and other samples were marked with ×.
[Evaluation of oxidation by-products]
A sealed container enclosing the oxygen-absorbing resin composition used for the evaluation of the oxygen-absorbing performance was stored at 30 ° C., and approximately 50 cc of oxygen was absorbed per 1 g of the oxygen-absorbing resin composition. At this time, 5 cc of the gas in the sealed container was collected with a syringe, and the analysis of oxidation by-products was performed by GC-MS (TEKMAR-4000: Agilent Co. column: DB-1) by the purge and trap method. The area value of the spectrum of the obtained gas chromatograph was defined as the amount of oxidation by-products, and the value of less than 2.5 × 10 ⁷ was rated as “◯” and the value of 2.5 × 10 ⁷ or more as “×”.
[Evaluation of mechanical strength]
An oxygen-absorbing resin composition pellet was sandwiched between hot plates to produce a sheet having a thickness of 0.3 mm at 200 ° C. A dumbbell-shaped test piece was cut out from this sheet. This test piece was stored in a sealed container having an internal volume of 85 cc at 30 ° C. to absorb 15 cc / g of oxygen. Using this test piece, a tensile test (tensile speed: 500 mm / min) was performed by a tensile tester (Tensilon UCT-5T: TS Engineering Co., Ltd.) in an environment of 23 ° C.-50% RH, and elongation at break Was measured. The elongation at break obtained was divided by the elongation at break before oxygen absorption, and the case where the elongation at break of 50% or more was maintained as compared with before oxygen absorption was rated as “、” and the case where it was less than 50% as “x”.

[Example 1]
Hydrogenated styrene-butadiene-styrene triblock copolymer resin (Tuftec P2000) with respect to 95 parts by weight of linear low density polyethylene resin (Evolue 0510B: Mitsui Chemicals, Inc.) using a metallocene base resin as a catalyst. Asahi Kasei Co., Ltd.) 5 parts by weight and cobalt stearate (Dainippon Ink and Chemicals Co., Ltd.) with a cobalt metal content of 9.5 wt% are blended at 150 ppm in terms of cobalt and preliminarily used in a stir dryer (Dalton Co., Ltd.). After kneading, it was put into a hopper. Next, using a twin-screw extruder (TEM35B: Toshiba Machine Co., Ltd.) equipped with a strand die at the outlet portion, it was extruded into a strand shape while pulling a high vacuum vent at a screw rotation speed of 100 rpm, and an oxygen absorbent resin composition A pellet was prepared. About this material, when the oxygen absorption performance, the amount of oxidation byproducts, and the mechanical strength were evaluated by the above-mentioned methods, the oxygen absorption performance, the oxygen absorption performance was small, the oxidation byproducts were small, and the mechanical strength was reduced. It was small.
[Example 2]
An oxygen-absorbing resin composition was prepared and evaluated in the same manner as in Example 1 except that the base resin was a metallocene-catalyzed linear low-density polyethylene resin LLDPE (ZM063: Ube Industries, Ltd.). The produced oxygen-absorbing resin composition exhibited good oxygen-absorbing performance, had few oxidation by-products, and had a small decrease in mechanical strength.

[Comparative Example 1]
The oxygen-absorbing resin composition was prepared and evaluated in the same manner as in Example 1 except that the base resin was a high-pressure method low-density polyethylene (JB221R: Nippon Polyolefin Co., Ltd.), which cannot be said to be linear low-density polyethylene. It was. The produced oxygen-absorbing resin composition had good oxygen-absorbing performance, but due to the structure containing complex long-chain branches, there were many oxidation by-products and the mechanical strength was greatly reduced.
[Comparative Example 2]
An oxygen-absorbing resin composition was prepared and evaluated in the same manner as in Example 1 except that the base resin was a multi-site catalyst linear low density polyethylene (ULTZEX 2020SB: Mitsui Chemicals). The produced oxygen-absorbing resin composition had good oxygen-absorbing performance, but it had many branched byproducts derived from 4-methylpentene-1, so that there were many oxidation by-products, particularly acetone. This oxygen-absorbing resin composition was not measured for mechanical strength.
[Comparative Example 3]
An oxygen-absorbing resin composition was prepared and evaluated in the same manner as in Example 1 except that the base resin was a random copolymer resin of ethylene propylene as a multisite catalyst (RE386: Nippon Polypro Co., Ltd.). The produced oxygen-absorbing resin composition had good oxygen-absorbing performance, but because there were many branches, there were very many oxidation by-products and the mechanical strength was greatly reduced.
Table 1 shows the results of Examples and Comparative Examples. As is clear from Table 1, depending on the branching state of the base resin, the oxygen absorption performance, the amount of oxidation by-products, and the degree of mechanical strength decrease due to oxidation are clearly shown. The difference was recognized.

Claims (8)

Linear low density polyethylene resin (A), which is a resin other than resin (A) and contains resin (B) that triggers oxidation of resin (A), and resin (B) is in the matrix of resin (A) In the resin composition in which the oxidation reaction of the matrix resin (A) proceeds and absorbs oxygen when it comes into contact with oxygen, the resin (A) has a side chain of 0.003 eq / g or less. It is a resin composed of linear hydrocarbons, the resin (A) content is 90 to 99% by weight, the resin (B) content is 1 to 10% by weight, and the resin (B) is hydrogenated. It is a styrene-diene copolymer, the oxygen-absorbing resin composition further contains 10 to 3000 ppm of a transition metal catalyst (C) in terms of metal weight , and the transition metal catalyst (C) is present at least in the resin (A). An oxygen-absorbing resin composition characterized by comprising:   The oxygen-absorbing resin composition according to claim 1, wherein the resin (A) is a resin polymerized using a single site catalyst.   The oxygen-absorbing resin composition according to claim 1 or 2, wherein the resin (A) is a resin using a metallocene catalyst as a polymerization catalyst.   The oxygen-absorbing resin composition according to claim 1, wherein the hydrogenated styrene-diene copolymer is a hydrogenated styrene-isoprene block copolymer or a hydrogenated styrene-butadiene block copolymer.   The oxygen-absorbing resin composition according to claim 4, wherein the hydrogenated styrene-diene copolymer is a hydrogenated styrene-isoprene-styrene triblock copolymer or a hydrogenated styrene-butadiene-styrene triblock copolymer. The oxygen absorber containing the oxygen absorptive resin composition of any one of Claims 1-5 . The laminated body which has at least 1 layer containing the oxygen absorptive resin composition of any one of Claims 1-5 . The laminate according to claim 7 , further comprising at least one oxygen barrier layer.