JP2009215400A - Oxygen absorbing resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oxygen absorbing resin composition having excellent oxygen absorbency, in particular, producing no unpleasant odor by oxygen absorption, and having a high initial oxygen absorption rate. <P>SOLUTION: The oxygen absorbing resin composition contains a thermoplastic resin (A) consisting of an allyl ether structural unit expressed by general formula (I). The oxygen absorbing resin composition contains a transition metal salt (B) and a matrix resin (C) if necessary. In formula, R<SP>1</SP>and R<SP>2</SP>each represent hydrogen atom, alkyl group which may have a substituent, aryl group which may have a substituent, or alkyl aryl group which may have a substituent, or R<SP>1</SP>and R<SP>2</SP>may together form a single bond, an alkylene group which may have a substituent, or an oxyalkylene group. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an oxygen-absorbing resin composition that is used for products that are highly sensitive to oxygen and easily deteriorated in quality, particularly packaging materials such as foods, beverages, pharmaceuticals, and cosmetics, and containers.

  It is important from the viewpoint of improving the shelf life of products to prevent products that are sensitive to oxygen and easily deteriorate in quality, especially foods, beverages, pharmaceuticals, and cosmetics from deterioration due to oxygen present in the atmosphere. . As such a method, a method of coexisting an inorganic oxygen absorbent in a package for packaging products such as foods, beverages, pharmaceuticals, and cosmetics, and a method of using a multilayer structure having a layer made of a gas barrier resin as a packaging material It has been known.

  As an inorganic oxygen absorbent that coexists in a package, for example, an oxygen absorbent mainly composed of iron powder is widely used. A method of absorbing oxygen invading from inside and outside the package by filling an oxygen absorbent mainly composed of iron powder into a small sachet and coexisting in the package is inexpensive, and the oxygen absorption rate Also has the feature of being fast. However, if a metal detector is used to detect foreign objects in the packaged product, or if the contents, especially food, are heated with a microwave oven while being packaged, iron powder is present. Is inconvenient. In addition, when such an oxygen absorbent coexists with food, particularly as a sachet, there is a risk of accidental eating. As a technique to prevent accidental eating, packaging materials are prepared by pre-kneading inorganic oxygen absorbers such as iron powder and organic oxygen absorbers typified by ascorbic acid compounds into various resins that make up packaging materials. In this method, there is a problem that the appearance of the package is deteriorated and the oxygen absorption rate of the obtained packaging material is greatly reduced.

  On the other hand, a gas barrier resin such as an ethylene-vinyl alcohol copolymer (hereinafter sometimes abbreviated as EVOH) is a material having excellent oxygen gas barrier properties and carbon dioxide gas barrier properties. Since such a resin can be melt-molded, it is laminated with a layer of thermoplastic resin (polyolefin, polyester, etc.) excellent in moisture resistance, mechanical properties, etc., and is suitably used as a multilayer packaging material. However, the gas permeability of these gas barrier resins is not completely zero and permeates a non-negligible amount of gas. In order to reduce such gas permeation, in particular oxygen permeation, which has a great influence on the contents of the package, in particular the quality of the food, and oxygen already present in the package at the time of packaging of the contents In order to absorb and remove oxygen, it is known to use an oxygen absorbent mixed with the packaging material.

  For example, as a composition suitable for oxygen absorption, a composition containing a transition metal catalyst and an ethylenically unsaturated hydrocarbon (see Patent Document 1) has been proposed. Moreover, the resin composition containing EVOH and an oxygen absorber is proposed (refer patent document 2, patent document 3, and patent document 4). In particular, since a resin composition containing EVOH can be melt-molded in the same manner as EVOH, it can be suitably used for various packaging materials.

  However, when a packaging material or a resin composition in which the above oxygen absorbent is mixed is used as a packaging material, the oxygen absorbent is decomposed as oxygen absorption proceeds, and an unpleasant odor may be generated. Therefore, there is still room for improvement in applications where odorlessness is required or in applications where fragrance is important.

  As a result of repeated researches to solve the above-mentioned problems, some of the present inventors have developed a thermoplastic resin and a transition metal salt that do not generate an unpleasant odor and have a carbon-carbon double bond substantially only in the main chain. The present invention has led to the invention of an oxygen-absorbing resin composition containing benzene (see Patent Document 5). However, especially when food is stably stored for a long period of time, it is desirable that the packaging material has an oxygen barrier property, that is, an oxygen absorption capacity as high as possible. As a technique for this, increasing the oxidizable sites in the oxygen-absorbing resin composition, that is, increasing the content of carbon-carbon double bonds, it is considered to be an oxidizable site having relatively high reactivity in the main chain. The density | concentration of the allyl site | part (carbon atom site | part adjacent to a carbon-carbon double bond) obtained is improved, and the reaction point for making oxygen absorb is mentioned. In addition, the oxygen absorption is improved by increasing the allyl moiety, while suppressing the occurrence of a substance having an unpleasant odor due to the breakage of the carbon-carbon bond, substantially only the main chain. It is conceivable that the allyl moiety is retained in to suppress the generation of odorous substances. However, when many carbon-carbon double bonds are present in the main chain in order to have many allyl sites in the main chain, such a material is generally inferior in stability and workability during melt molding. There is a problem in that coloring and unevenness are likely to occur. Therefore, in order to improve the oxygen absorption capacity, it is not necessary to increase the carbon-carbon double bonds in the material used as the oxygen-absorbing resin composition.

  An oxygen-absorbing resin composition containing a polymer having a polyether unit and an oxidation catalyst which is a transition metal compound, and further containing a radical scavenger in a specific blending ratio is also disclosed (Patent Documents 6 and 7). reference). However, when a polymer having a polyalkylene ether unit, which is actually disclosed, is used as a component of an oxygen-absorbing resin composition, the amount of oxygen absorption is secured, but the generation of odor during oxygen absorption is practical. This is an uncontrollable result. In addition, according to the disclosure, irradiation with active energy rays such as UV is suitable for use in developing oxygen absorption performance, and in view of industrial practicality, operation is complicated in actual use. Have the problem of becoming.

  Moreover, in the field of food packaging, there are cases where it is required to quickly remove residual oxygen inside the package for further improvement of storage stability. The oxygen absorption rate for a short period of time is required to be large.

Japanese Patent Laid-Open No. 5-115776 JP 2001-106866 A JP 2001-106920 A JP 2002-146217 A Japanese Patent Laying-Open No. 2005-187808 JP 2003-064250 A JP 2003-113111 A

  An object of the present invention is to solve the above-described problems, and has excellent oxygen absorbability, does not generate unpleasant odor due to oxygen absorption, and has sufficient dispersibility to improve the initial oxygen absorption rate. The object is to provide an oxygen-absorbing resin composition.

  According to the present invention, the above object is achieved by the following general formula (I):

(Wherein R ¹ and R ² are each a hydrogen atom, an alkyl group which may have a substituent, an aryl group which may have a substituent, or an alkylaryl which may have a substituent) R ¹ and R ² may be combined together to form a single bond or an alkylene or oxyalkylene group which may have a substituent.
An oxygen-absorbing resin composition containing a thermoplastic resin (A) (hereinafter referred to as a thermoplastic resin (A)) consisting of an allyl ether structural unit represented by the formula (hereinafter simply referred to as a structural unit (I)) is provided. Is achieved. In a preferred embodiment, the plastic resin (A) is poly (2-butene-1,4-diol).

  According to the present invention, the above object can also be achieved by providing an oxygen-absorbing resin composition comprising a thermoplastic resin (A) and a transition metal salt (B). In a preferred embodiment, the transition metal salt (B) is at least one metal salt selected from the group consisting of iron salt, nickel salt, copper salt, manganese salt and cobalt salt.

  The oxygen-absorbing resin composition may further contain a matrix resin (C). In a preferred embodiment, the matrix resin (C) is an ethylene-vinyl alcohol copolymer having an ethylene content of 5 to 60 mol% and a saponification degree of 90% or more. In a preferred embodiment, particles made of the thermoplastic resin (A) are dispersed in the matrix of the matrix resin (C).

  According to the present invention, an oxygen-absorbing resin composition having excellent oxygen absorption, no unpleasant odor due to oxygen absorption, excellent initial oxygen absorption rate and transparency, and the resin composition For example, a multilayer film including a layer made of the resin composition, a multilayer container, and the like can be obtained. In particular, the container containing the resin composition is useful for storing products such as foods and cosmetics that are easily deteriorated by oxygen and in which fragrance is important. According to the present invention, an oxygen-absorbing resin composition that is also useful as an oxygen scavenger that is easy to handle can be obtained.

Hereinafter, specific embodiments of the present invention will be described in detail.
(1) Thermoplastic resin (A)
The oxygen-absorbing resin composition of the present invention contains a thermoplastic resin (A) composed of the structural unit (I). In the formula, the number of carbon atoms of the alkyl group represented by each of R ¹ and R ² is preferably 1 to 5, the number of carbon atoms of the aryl group is preferably 6 to 10, and the number of carbon atoms of the alkylaryl group is Is 7-11. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, and a butyl group, examples of the aryl group include a phenyl group, and examples of the alkylaryl group include a benzyl group. The number of carbon atoms of the alkylene group or oxyalkylene group represented by R ¹ and R ^{2 taken} together is preferably 1 to 10, more preferably 2 to 5. These alkyl groups, aryl groups, alkylaryl groups, and alkylene groups include halogen atoms such as chlorine atoms and bromine atoms, alkoxy groups such as methoxy groups and ethoxy groups, alkoxycarbonyl groups such as methoxycarbonyl groups and ethoxycarbonyl groups. It may have a substituent.

  Specific examples of the thermoplastic resin (A) include poly (2-butene-1,4-diol) and poly (2-methyl-2-butene-1,4-diol) from the viewpoint of easy industrial production. ), Poly (1,4-dimethyl-2-butene-1,4-diol), and the like. Among these, poly (2-butene-1,4-diol) is particularly suitable because it is easy to obtain and manufacture and has excellent oxygen absorption performance.

  The thermoplastic resin (A) has a carbon-carbon double bond in the structural unit (I) and has an allyl moiety, so that it can efficiently react with oxygen. As a result, excellent oxygen Absorption function is obtained. In the present specification, the “carbon-carbon double bond” does not include a carbon-carbon double bond in an aromatic ring.

  In the structural unit (I) of the thermoplastic resin (A), since the carbon-carbon double bond is present in the main chain of the polymer, the carbon-carbon double bond and its allyl moiety are partially oxidized by oxygen absorption. Even if it is cleaved, a low molecular weight fragment is hardly generated as in the case where the carbon-carbon double bond in the side chain is cleaved, and an odor substance is hardly generated.

  The weight average molecular weight (Mw) of the thermoplastic resin (A) is preferably 1000 to 100,000, more preferably 5000 to 80000, and further preferably 10000 to 60000. When the weight average molecular weight (Mw) of the thermoplastic resin (A) is less than 1000 or more than 100,000, the moldability of the resulting oxygen-absorbing resin composition, handling properties, The mechanical properties such as elongation tend to decrease.

  As a method for producing the thermoplastic resin (A), for example, in the case of poly (2-butene-1,4-diol), (i) 2,5-dihydrofuran is used as a raw material, a molybdenum complex or a ruthenium complex is used. Examples include a method of performing ring-opening metathesis polymerization as a catalyst, and (ii) a method of performing acyclic diene metathesis polymerization using diallyl ether as a raw material and using a molybdenum complex or a ruthenium complex as a catalyst. Among these, the method (i) is preferable.

As a catalyst for ring-opening metathesis polymerization in the method (i), and as molybdenum complex used as the acyclic diene metathesis polymerization catalyst in the process of (ii) is, for example, _{^{Mo (N-2,6-Pr i}} 2 C ^{_{6 H 3) (CHBu t)}} (OBu t) 2, Mo (N-2,6-Pr i 2 C 6 H 3) (CHBu t) [OCMe (CF 3) 2], Mo (N-2,6 ^{_{-Pr i 2 C 6 H 3)}} (CHBu t) [OCMe (CF 3) 2] 2, Mo (N-2,6-Pr i 2 C 6 H 3) (CHCMe 2 Ph) (OBu t) 2, ^{_{Mo (N-2,6-Pr i}} 2 C 6 H 3) (CHCMe 2 Ph) [OCMe (CF 3) 2], Mo (N-2,6-Pr i 2 C 6 H 3) (CHCMe 2 Ph ) [OCMe (CF ₃ ) ₂ ] ₂ , ^{_{Mo (N-2,6-Pr i}} 2 C 6 H 3) (CHCMe 2 Ph) (BIPHEN), Mo (N-2,6-Pr i 2 C 6 H 3) (CHCMe 2 Ph) (BINO) ( And molybdenum alkylidene complexes such as THF). Examples of the ruthenium complex include benzylidene (1,3-dimesityrylimidazolidin-2-ylidene) (tricyclohexylphosphine) ruthenium dichloride, (1,3-dimesitylimidazolidin-2-ylidene) (3-methyl- 2-butene-1-ylidene) (tricyclopentylphosphine) ruthenium dichloride, benzylidene (1,3-dimesityloctahydrobenzimidazol-2-ylidene) (tricyclohexylphosphine) ruthenium dichloride, benzylidene [1,3-di ( 1-phenylethyl) -4-imidazoline-2-ylidene] (tricyclohexylphosphine) ruthenium dichloride, benzylidene (1,3-dimesityl-2,3-dihydrobenzimidazol-2-ylidene) (tricyclohexylphosphine) ) Ruthenium dichloride, benzylidene (tricyclohexylphosphine) (1,3,4-triphenyl-2,3,4,5-tetrahydro-1H-1,2,4-triazol-5-ylidene) ruthenium dichloride, (1 , 3-Diisopropylhexahydropyrimidin-2-ylidene) (ethoxymethylene) (tricyclohexylphosphine) ruthenium dichloride, benzylidene (1,3-dimesitylimidazolidine-2-ylidene) pyridine ruthenium dichloride, etc. Ruthenium carbene complex in which one carbene and one neutral electron donor other than nitrogen-containing heterocyclic carbene are bonded; benzylidenebis (1,3-dicyclohexylimidazolidine-2-ylidene) ruthenium dichloride, benzylidenebis (1,3-diiso Ruthenium carbene complexes in which two nitrogen-containing heterocyclic carbenes are bonded, such as ropyl-4-imidazoline-2-ylidene) ruthenium dichloride; (1,3-dimesitylimidazolidin-2-ylidene) (2-isopropoxyphenyl) Methylene) ruthenium dichloride, (1,3-dimesitylimidazolidine-2-ylidene) (2-ethoxyphenylmethylene) ruthenium dichloride, and the like, having one nitrogen-containing heterocyclic carbene and having a coordinating ether bond And a ruthenium carbene complex contained in the carbene.

Among these, the stability of the catalyst solution, from the viewpoint of ^{_{activity, Mo (N-2,6-Pr}} i 2 C 6 H 3) (CHBu t) [OCMe (CF 3) 2], benzylidene (1 , 3-Dimesitylimidazolidin-2-ylidene) (tricyclohexylphosphine) ruthenium dichloride and (1,3-Dimesitylimidazolidin-2-ylidene) (2-isopropoxyphenylvinylidene) ruthenium dichloride Is preferred.

  Both the ring-opening metathesis polymerization in the method (i) and the acyclic diene metathesis polymerization in the method (ii) can be carried out in the absence or presence of a solvent. Solvents that can be used are not particularly limited as long as they are inert to ring-opening metathesis polymerization and acyclic diene metathesis polymerization reactions. For example, aliphatic hydrocarbons such as hexane, heptane, octane, nonane, decane, undecane, and dodecane. Aromatic hydrocarbons such as toluene, benzene and xylene; ethers such as tetrahydrofuran; halogenated hydrocarbons such as methylene chloride, chloroform and carbon tetrachloride. When using a solvent, there is no restriction | limiting in particular in the usage-amount, Usually, it is the range of 0.1-20 mass times with respect to a raw material. The temperature at which ring-opening metathesis polymerization and acyclic diene metathesis polymerization are carried out varies depending on whether or not a solvent is used and the boiling point of the solvent to be used, but usually in a temperature range of −78 to 200 ° C. Usually, it is performed within 20 hours. In carrying out, it is preferable to carry out in an inert gas atmosphere.

  In the present invention, an antioxidant may be added to the thermoplastic resin (A). Examples of the antioxidant include 2,5-di-t-butylhydroquinone, 2,6-di-t-butyl-p-cresol, 4,4′-thiobis (6-t-butylphenol), 2,2 ′. -Methylenebis (4-methyl-6-t-butylphenol), octadecyl-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate, 4,4'-thiobis (6-t- Butylphenol), 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, pentaerythritol tetrakis (3-laurylthiopropionate), 2,6 -Di-t-butyl-4-methylphenol, 2,2-methylenebis- (6-t-butyl-p-cresol), triphenyl phosphite, tris- Nonylphenyl) phosphite, and the like dilauryl thiodipropionate.

  When an antioxidant is added to the thermoplastic resin (A), the amount thereof is the type and amount of each component constituting the oxygen-absorbing resin composition of the present invention, and the use of the oxygen-absorbing resin composition of the present invention. It can be determined as appropriate in consideration of the purpose and storage conditions. For example, when the thermoplastic resin (A) is stored at a relatively low temperature or in an inert gas atmosphere, or when the oxygen-absorbing resin composition of the present invention is produced by melt-kneading in a nitrogen-sealed state, etc. The amount of antioxidant may be small. Further, when a relatively large amount of the transition metal salt (B) described later is added, even if a relatively large amount of an antioxidant is added to the thermoplastic resin (A), an oxygen-absorbing resin having a good oxygen-absorbing function A composition can be obtained. The addition amount of the antioxidant is usually preferably 0.01 to 1% by mass, and preferably 0.02 to 0.5% by mass based on the total mass of the thermoplastic resin (A) and the antioxidant. Is more preferable, and it is further more preferable that it is 0.03-0.3 mass%. When the addition amount of the antioxidant exceeds 1% by mass, the reaction between the thermoplastic resin (A) and oxygen is hindered, and the oxygen-absorbing function of the oxygen-absorbing resin composition of the present invention may be insufficient. . On the other hand, when the addition amount of the antioxidant is less than 0.01% by mass, the absorption of oxygen proceeds during storage or melt-kneading of the thermoplastic resin (A), and oxygen is absorbed before actual use of the resin composition. Absorption function may deteriorate.

(2) Transition metal salt (B)
The oxygen-absorbing resin composition of the present invention contains a transition metal salt (B) as necessary. Examples of the transition metal contained in the transition metal salt (B) include iron, nickel, copper, manganese, cobalt, rhodium, titanium, chromium, vanadium, and ruthenium. Among these, iron, nickel, copper, manganese, and cobalt are preferable, manganese or cobalt is more preferable, and cobalt is more preferable.

  As a counter ion of the transition metal contained in the transition metal salt (B), an anion derived from an organic acid is preferable. Examples of the organic acid include acetic acid, stearic acid, dimethyldithiocarbamic acid, palmitic acid, and 2-ethylhexanoic acid. , Neodecanoic acid, linoleic acid, toluic acid, oleic acid, capric acid, naphthenic acid and the like. As the transition metal salt (B), cobalt 2-ethylhexanoate, cobalt neodecanoate and cobalt stearate are particularly preferable.

  The transition metal salt (B) is preferably in the range of 1 to 50000 ppm, more preferably 5 to 10000 ppm, and even more preferably 10 to 5000 ppm in terms of transition metal, based on the mass of the thermoplastic resin (A). Blend. As described later, when the oxygen-absorbing resin composition of the present invention contains a matrix resin (C) in addition to the thermoplastic resin (A), the transition metal salt (B) contains the thermoplastic resin (A) and Based on the total mass of the matrix resin (C), it is blended in the range of 1 to 50000 ppm in terms of transition metal, more preferably 5 to 10000 ppm, and further preferably 10 to 5000 ppm. If the blending amount of the transition metal salt (B) is less than 1 ppm in terms of transition metal, the oxygen-absorbing function of the obtained oxygen-absorbing resin composition may be insufficient, while if it exceeds 50000 ppm, the obtained oxygen absorption In some cases, the thermal stability of the conductive resin composition decreases, and the generation of gels and blisters becomes significant.

(3) Matrix resin (C)
The oxygen-absorbing resin composition of the present invention contains a matrix resin (C) as necessary. The matrix resin (C) functions as a support for diluting or dispersing the thermoplastic resin (A) and imparts the characteristics of the matrix resin (C) to the oxygen-absorbing resin composition of the present invention. . The matrix resin (C) to be contained can be appropriately selected according to the purpose of use of the oxygen-absorbing resin composition of the present invention. For example, when it is desired to impart gas barrier properties to the oxygen-absorbing resin composition of the present invention, a gas barrier resin is used as the matrix resin (C). When other functions are desired, a resin is selected according to the purpose. For example, when the oxygen-absorbing resin composition of the present invention containing a gas barrier resin is used as a molded body such as a container, the gas barrier resin has a function of controlling the movement of oxygen from the outside through the molded body.

Among the matrix resins (C), as the gas barrier resin (hereinafter referred to as gas barrier resin (C-1)), the oxygen transmission rate is 500 ml · 20 μm / m ² · day · atm (20 ° C., 65% RH). It is preferable to use a resin having the following gas barrier properties. This oxygen permeation rate was measured in an environment of 20 ° C. and a relative humidity of 65%. The oxygen permeation rate of oxygen permeating through a film having an area of 1 m ² and a thickness of 20 μm in a day with an oxygen differential pressure of 1 atm. It means that the volume is 500 ml or less. When a resin having an oxygen permeation rate exceeding 500 ml · 20 μm / m ² · day · atm is used, the resulting gas barrier property of the oxygen-absorbing resin composition tends to be insufficient. The oxygen permeation rate of the gas barrier resin (C-1) is more preferably 100 ml · 20 μm / m ² · day · atm or less, still more preferably 20 ml · 20 μm / m ² · day · atm or less, and most preferably. Is 5 ml · 20 μm / m ² · day · atm or less. By containing such a gas barrier resin (C-1) in the thermoplastic resin (A), an oxygen absorbing function is exhibited in addition to the gas barrier property, and an oxygen absorbing resin composition having a high gas barrier property is obtained. be able to.

  Examples of the gas barrier resin (C-1) as described above include a polyvinyl alcohol resin (C-1-1), a polyamide resin (C-1-2), and a polyvinyl chloride resin (C-1-3). And polyacrylonitrile resin (C-1-4). As gas barrier resin (C-1), 1 type may be used among these resins, and 2 or more types may be mixed and used for it. Among the above, as the gas barrier resin (C-1), the polyvinyl alcohol resin (C-1-1) is preferable, and ethylene-vinyl alcohol copolymer having an ethylene content of 5 to 60 mol% and a saponification degree of 90% or more is preferable. The coalescence (hereinafter referred to as EVOH) is more preferable.

  Among the gas barrier resins (C-1), polyvinyl alcohol resins (C-1-1) are vinyl ester homopolymers or copolymers of vinyl esters and other monomers (particularly vinyl esters). And a copolymer of ethylene and saponification using an alkali catalyst or the like. Examples of vinyl esters include vinyl acetate, but other fatty acid vinyl esters such as vinyl propionate and vinyl pivalate can also be used.

  The saponification degree of the vinyl ester component of the polyvinyl alcohol-based resin (C-1-1) is preferably 90% or more, more preferably 95% or more, and further preferably 96% or more. If the degree of saponification is less than 90 mol%, the gas barrier properties under high humidity are reduced. In particular, when the polyvinyl alcohol-based resin (C-1-1) is EVOH, if the degree of saponification is less than 90 mol%, the thermal stability becomes insufficient, and the molded product is likely to contain gels and blisters.

  Among the polyvinyl alcohol resins (C-1-1), EVOH is preferably used because it can be melt-molded and has good gas barrier properties under high humidity.

  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 even more 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, more preferably 50 mol% or less.

  As described above, preferred EVOH has an ethylene content of 5 to 60 mol% and a saponification degree of 90% or more. When a multilayer container including a layer made of the oxygen-absorbing 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 degree of saponification Is preferably 90% or more and less than 99% EVOH.

  In addition, when a material having a higher level of impact resistance and gas barrier properties is desired, the ethylene content is 25 mol% or more and 55 mol% or less, and the saponification degree is 90% or more and less than 99%. EVOH (C-1-1a) of the above and EVOH (C-1-1b) having an ethylene content of 25 mol% or more and 55 mol% or less and a saponification degree of 99% or more are represented by (C-1- It is preferable to use the mixture so that the blending mass ratio of 1a) / (C-1-1b) is 5/95 to 95/5. In addition, when EVOH consists of a mixture of 2 or more types of EVOH from which ethylene content differs in this way, let the average value calculated from mixing mass ratio be ethylene content.

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

  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 propylene, 1-butene, isobutene, 4-methyl-1-pentene, 1-hexene, 1-octene and other α-olefins; itaconic acid, methacrylic acid, acrylic acid, maleic anhydride Unsaturated carboxylic acids such as acids, salts thereof, partial or complete esters thereof, nitriles thereof, amides thereof, anhydrides thereof; vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri (β-methoxyethoxy) silane, γ-methacryloxy Examples thereof include vinyl silane compounds such as propyltrimethoxysilane; unsaturated sulfonic acids or salts thereof; alkyl thiols; vinyl pyrrolidones.

  Among them, when EVOH contains 0.0002 to 0.2 mol% of a vinylsilane compound as a copolymerization component, the oxygen-absorbing resin composition of the present invention containing EVOH is used as a base resin (for example, polyester). At the same time, when co-extrusion molding or co-injection molding is performed to obtain a multilayer structure, the consistency of the melt viscosity with the base resin is improved, and a homogeneous molded product can be produced. As the vinylsilane compound, vinyltrimethoxysilane, vinyltriethoxysilane and the like are preferable.

  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-extrusion molded product or co-injected molded product is obtained. Here, as the boron compound, boric acids such as orthoboric acid, metaboric acid and tetraboric acid, boric acid esters such as triethyl borate and trimethyl borate, alkali metal salts and alkaline earth metal salts of the above various boric acids, Examples thereof include borates such as borax and borohydrides such as sodium borohydride. Of these compounds, orthoboric acid is preferred.

  When a boron compound is added to EVOH, the addition amount is preferably 20 to 2,000 ppm, more preferably 50 to 1,000 ppm in terms of boron. 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 2,000 ppm, gelation tends to occur, which may result in poor moldability.

  Adding an alkali metal salt to EVOH is also effective for improving interlayer adhesion and compatibility. The addition amount of the alkali metal salt is preferably 5 to 5,000 ppm, more preferably 20 to 1,000 ppm in terms of alkali metal, and still more preferably 30 to 500 ppm. Examples of the alkali metal salt include aliphatic metal carboxylates, aromatic carboxylates, phosphates, metal complexes, and the like such as lithium, sodium, and potassium. Examples thereof include sodium acetate, potassium acetate, sodium phosphate, lithium phosphate, sodium stearate, potassium stearate, sodium salt of ethylenediaminetetraacetic acid, and among these, sodium acetate, potassium acetate, and sodium phosphate are preferable.

  The addition amount of the phosphoric acid compound to EVOH is preferably in the range of 20 to 500 ppm, more preferably 30 to 300 ppm, and still more 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 melt flow rate (MFR) (at 210 ° C. under 2160 g load, based on JIS K 7210) is preferably 0.1 to 100 g / 10 min, more preferably 0.5 to 50 g / 10 min, still more preferably 1-30 g / 10 min.

  Of the gas barrier resin (C-1), the type of the polyamide resin (C-1-2) is not particularly limited. For example, polycaprolactam (nylon-6), polyundecanamide (nylon-11), polylaurolactam (nylon-12), polyhexamethylene adipamide (nylon-6,6), polyhexamethylene sebacamide (nylon) Aliphatic polyamide homopolymers such as -6,10); caprolactam / laurolactam copolymer (nylon-6 / 12), caprolactam / aminoundecanoic acid copolymer (nylon-6 / 11), caprolactam / ω-aminononane Acid copolymer (nylon-6 / 9), caprolactam / hexamethylene adipamide copolymer (nylon-6 / 6,6), caprolactam / hexamethylene adipamide / hexamethylene sebacamide copolymer (nylon Aliphatic polyamide copolymers such as -6/6, 6/6, 10); poly Taki silylene adipamide (MX- nylon), aromatic polyamides such as hexamethylene terephthalamide / hexamethylene isophthalamide copolymer (Nylon-6T / 6I), and the like. These polyamide resins (C-1-2) can be used alone or in combination of two or more. Among these, polycaprolactam (nylon-6) and polyhexamethylene adipamide (nylon-6, 6) are preferable from the viewpoint of gas barrier properties.

  Examples of the polyvinyl chloride resin (C-1-3) include vinyl chloride or vinylidene chloride homopolymers, and copolymers of vinyl chloride or vinylidene chloride with vinyl acetate, maleic acid derivatives, higher alkyl vinyl ethers, and the like. It is done.

  Examples of the polyacrylonitrile resin (C-1-4) include acrylonitrile homopolymers and copolymers of acrylonitrile and acrylic acid esters.

  When the oxygen-absorbing resin composition of the present invention contains a matrix resin (C) in addition to the thermoplastic resin (A) as a resin component, the total mass of the thermoplastic resin (A) and the matrix resin (C) Is 100% by mass, the thermoplastic resin (A) is preferably 30 to 1% by mass, and the matrix resin (C) is preferably 70 to 99% by mass. For example, when the matrix resin (C) is a gas barrier resin (C-1) and the ratio is less than 70% by mass, the gas barrier property of the resin composition against oxygen gas, carbon dioxide gas, etc. On the other hand, when it exceeds 99% by mass, the oxygen absorption function tends to decrease. The ratio of the thermoplastic resin (A) is more preferably 20 to 2% by mass, still more preferably 15 to 3% by mass, and the ratio of the matrix resin (C) is more preferably 80 to 98% by mass, and still more preferably. Is 85 to 97% by mass.

(4) Oxygen-absorbing resin composition and molded article using the same As described above, the oxygen-absorbing resin composition of the present invention contains the thermoplastic resin (A), and, if necessary, a transition metal. Contains salt (B), matrix resin (C), various additives, and the like.

  In the composition in which the oxygen-absorbing resin composition of the present invention contains a resin other than the thermoplastic resin (A) such as the matrix resin (C), the particles made of the thermoplastic resin (A) are the thermoplastic resin (A). It is recommended that the resin is dispersed in a matrix containing a resin (matrix resin (C)), transition metal salt (B), and various additives. For example, when the oxygen-absorbing resin composition of the present invention is composed of a thermoplastic resin (A), a transition metal salt (B), and a matrix resin (C), the particles composed of the thermoplastic resin (A) are transition metal salts (B ) And a matrix containing the matrix resin (C) are recommended. Various molded articles made of the oxygen-absorbing resin composition of the present invention in such a state are particularly excellent in oxygen absorption function and excellent in transparency. Furthermore, the function of the matrix resin (C) can be sufficiently obtained. For example, when the matrix resin (C) is a gas barrier resin (C-1), the gas barrier property is good.

  About the average particle diameter of the particle | grains which consist of the said thermoplastic resin (A), Preferably the long diameter is 4 micrometers or less, More preferably, it is 2 micrometers or less, More preferably, it is 1 micrometer or less. The average particle diameter of such thermoplastic resin (A) particles is a particle diameter obtained when measured by observation with a scanning electron microscope (SEM).

  The melt flow rate (MFR) (210 ° C., 2160 g load, based on JIS K 7210) of the oxygen-absorbing resin composition of the present invention is preferably 0.1 to 100 g / 10 min, more preferably 0.5 to 50 g / 10 min, more preferably 1-30 g / 10 min. When the melt flow rate of the resin composition is out of the above range, the workability during melt molding tends to deteriorate.

  The oxygen-absorbing resin composition of the present invention can exhibit a high oxygen absorption rate particularly in the initial stage of about 1 to 3 days after production.

  The components of the oxygen-absorbing resin composition of the present invention are mixed and then processed into a desired shape. The method for mixing the components of the oxygen-absorbing resin composition of the present invention is not particularly limited. The order of mixing the components is not particularly limited. For example, when the thermoplastic resin (A), the transition metal salt (B) and the matrix resin (C) are mixed, these may be mixed simultaneously, or the thermoplastic resin (A) and the transition metal salt (B) may be mixed. After mixing, you may mix with matrix resin (C).

  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.

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

  Hereinafter, the present invention will be specifically described with reference to examples and the like, but the present invention is not limited thereto. Analysis and evaluation in the following Examples and Reference Examples were performed as follows.

(1) Molecular structure of the thermoplastic resin (A):
It was determined by ¹ H-NMR (nuclear magnetic resonance) measurement (using “JNM-GX-500 type” manufactured by JEOL Ltd.) using CDCl ₃ as a solvent.

(2) Number average molecular weight and weight average molecular weight of the thermoplastic resin (A):
The measurement was performed by gel permeation chromatography (GPC) and expressed as a polystyrene conversion value. Detailed measurement conditions are as follows.
<Analysis conditions>
Apparatus: Shodex gel permeation chromatography (GPC) SYSTEM-11
Column: KF-806L (Shodex) Column temperature: 40 ° C
Mobile phase: Tetrahydrofuran Flow rate: 1.0 mL / min Detector: RI Filtration: 0.45 μm filter Concentration: 0.1%

(3) Ethylene content and saponification degree of EVOH:
It was calculated by ¹ H-NMR (nuclear magnetic resonance) measurement (using “JNM-GX-500 type” manufactured by JEOL Ltd.) using DMSO-d ₆ as a solvent.

(4) Measurement of dispersed particle size of thermoplastic resin (A) in oxygen-absorbing resin composition:
The pellets of the oxygen-absorbing resin composition obtained in each Example and Reference Example described later were cut with a microtome according to a conventional method, and platinum was deposited on the cross section under reduced pressure. The cross section on which platinum is deposited is photographed with a scanning electron microscope (SEM) at a magnification of 10,000 times from the direction perpendicular to the cut surface, and the particles 20 made of the thermoplastic resin (A) in the photograph. A region including about one was selected, the particle size of each particle image existing in the region was measured, the average value was calculated, and this was taken as the dispersed particle size. In addition, about the particle size of each particle | grain, the long diameter (longest part) of the particle | grains observed in a photograph was measured, and this was made into the particle size.

Synthesis Example 1 Synthesis of poly (2-butene-1,4-diol) (A-1) After substituting the inside of a 3000 mL three-necked flask equipped with a stirrer and a thermometer with dry nitrogen, 2,5-dihydro 700 g (1 mol) of furan was charged. Then ^Mo to ^{_{(N-2,6-Pr i 2}} C 6 H 3) (CHBu t) [OCMe (CF 3) 2] 17.4g (0.03mol) was added to the above solution, ring-opening metathesis at 27 ° C. Polymerization was performed. After 24 hours, analysis was performed by gas chromatography (manufactured by Shimadzu Corporation, GC-14B; column: manufactured by Chemicals Inspection Association, G-100). Thereafter, 11 g (150 mmol) of ethyl vinyl ether was added to stop the reaction.
To the obtained reaction solution, 1000 g of toluene was added and stirred at 30 ° C. for 30 minutes, and then 300 g of water was added. The lower layer was removed and this operation was repeated 3 times. The organic phase is concentrated under reduced pressure, and then dried at 1 Pa and 60 ° C. for 24 hours using a vacuum dryer, so that a poly ((weight average molecular weight (Mw) 20,000) and number average molecular weight (Mn) 18,000 poly ( 2-butene-1,4-diol) (hereinafter referred to as (A-1)) 206 g (yield based on 2,5-dihydrofuran: 30%) was obtained.

Example 1
Dry blend of EVOH 90g, ethylene content: 32 mol%, saponification degree: 99.6%, (A-1) 10 g and cobalt stearate (II) 0.08484 g (800 ppm as cobalt; vs. (A-1)) Then, using a roller mixer (LABO PLASTOMIL MODEL R100 manufactured by Toyo Seiki Co., Ltd.), the inside of the chamber was melt-kneaded while purging with nitrogen, and was taken out in a lump after 5 minutes. The obtained lump was cut into pellets to obtain oxygen-absorbing resin composition pellets composed of EVOH, (A-1) and cobalt stearate. When the cut surface of the pellet was observed by SEM, (A-1) having a particle diameter of 1 μm or less was dispersed in the matrix made of EVOH.

  The obtained pellets were crushed and a fine powder of the oxygen-absorbing resin composition was obtained through a 150-micron mesh. 0.1 g of the fine powder obtained was precisely weighed and placed in a standard bottle with a capacity of 260 ml filled with air containing 21:79 oxygen and nitrogen in a volume ratio. In order to set the relative humidity inside to 100% RH, the wall surface of this standard bottle is covered with filter paper containing water (impregnated with 6 g of water), and the mouth of the standard bottle is sealed with an epoxy resin using a multilayer sheet containing an aluminum layer And left in a thermostatic chamber at 23 ° C. After sealing, the internal air was sampled with a syringe over time, and the oxygen concentration was measured using gas chromatography. The holes vacated in the multilayer sheet at the time of sampling were sealed with epoxy resin each time. By calculating the amount of decrease in oxygen from the volume ratio of oxygen and nitrogen obtained by measurement, the oxygen absorption amount of the oxygen-absorbing resin composition in a 23 ° C., 100% RH atmosphere was determined. Table 1 and FIG. 1 show the oxygen absorption amount (integrated amount) per gram of the oxygen-absorbing resin composition after 2 days, 8 days, and 16 days from the time of encapsulation. Furthermore, when five panelists conducted sensory evaluation of the odor of the air in the standard bottle after 16 days, it was confirmed that there was almost no odor.

Example 2
In Example 1, an oxygen-absorbing resin composition was prepared in the same manner as in Example 1 except that cobalt stearate was not added. When the cut surface of the pellet was observed by SEM, (A-1) having a particle diameter of 1 μm or less was dispersed in the matrix made of EVOH. The obtained pellets were crushed and the oxygen absorption amount was evaluated in the same manner as in Example 1. The results are shown in Table 1 and FIG. Further, when the odor in the standard bottle after 16 days was evaluated in the same manner as in Example 1, it was confirmed that there was almost no odor.

Reference example 1
In Example 1, an oxygen-absorbing resin composition was prepared in the same manner as in Example 1 except that 10 g of polyoctenylene (manufactured by Degussa) having a number average molecular weight of 60,000 was used instead of 10 g of (A-1). When the cut surface of the pellet was observed with an SEM, polyoctenylene having a particle diameter of 1 μm or less was dispersed in a matrix made of EVOH. The obtained pellets were crushed and the oxygen absorption amount was evaluated in the same manner as in Example 1. The results are shown in Table 1 and FIG. Further, when the odor in the standard bottle after 16 days was evaluated in the same manner as in Example 1, it was confirmed that there was almost no odor.

  From Table 1 and FIG. 1, the oxygen-absorbing resin composition containing the thermoplastic resin (A) composed of the structural unit (I) of the present invention exhibits excellent oxygen-absorbing ability and hardly generates odor. Recognize.

It is the graph which plotted oxygen absorption amount in 23 degreeC and 100-% RH atmosphere of the oxygen absorption composition of Example 1, 2 and Reference Example 1 with respect to time (days).

Claims (7)

The following general formula (I)

(Wherein R ¹ and R ² are each a hydrogen atom, an alkyl group which may have a substituent, an aryl group which may have a substituent, or an alkylaryl which may have a substituent) R ¹ and R ² may be combined together to form a single bond or an alkylene or oxyalkylene group which may have a substituent.
An oxygen-absorbing resin composition containing a thermoplastic resin (A) comprising an allyl ether structural unit represented by The oxygen-absorbing resin composition according to claim 1, wherein the thermoplastic resin (A) is poly (2-butene-1,4-diol). An oxygen-absorbing resin composition comprising the thermoplastic resin (A) and a transition metal salt (B). The oxygen-absorbing resin composition according to claim 3, wherein the transition metal salt (B) is at least one metal salt selected from the group consisting of iron salt, nickel salt, copper salt, manganese salt and cobalt salt. object. The oxygen-absorbing resin composition according to any one of claims 1 to 4, further comprising a matrix resin (C). The oxygen-absorbing resin composition according to claim 5, wherein the matrix resin (C) is an ethylene-vinyl alcohol copolymer having an ethylene content of 5 to 60 mol% and a saponification degree of 90% or more. The oxygen-absorbing resin composition according to claim 5 or 6, wherein particles made of the thermoplastic resin (A) are dispersed in a matrix of the matrix resin (C).

Images