JP2011157406A - Method for suppressing generation of odor component from oxygen-absorbing resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for suppressing generation of an odor component from an oxygen-absorbing resin composition (A). <P>SOLUTION: The method for suppressing generation of the odor component from the oxygen-absorbing resin composition (A) is provided, and the method includes a step for dispersing a compound (a) having a carbon-carbon double bond in a resin containing an ethylene-vinyl alcohol copolymer (b) to obtain the oxygen-absorbing resin composition (A). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for suppressing the generation of odor components from an oxygen-absorbing resin composition.

  In recent years, a container using an oxygen-absorbing resin layer made of an oxygen-absorbing resin composition that absorbs oxygen in the container in order to enhance the storage stability of the contents of the packaging container, particularly food, beverages, pharmaceuticals, cosmetics, A container using a multilayer structure composed of an oxygen-absorbing resin layer and a gas barrier layer has been proposed.

  The compound used in the oxygen-absorbing resin composition has a carbon-carbon double bond, and this double bond is considered to consume oxygen by reacting with oxygen (oxidation reaction). However, there is a problem in that an unpleasant odor component is generated by this oxidation reaction and is transferred to the contents of the container.

  In order to solve the problem of such an odor component, Patent Documents 1 to 3 disclose a multilayer structure having an oxygen absorbing layer and a deodorizing layer. These deodorizing layers contain a deodorizing agent.

  However, the deodorizing agent may color the deodorizing layer, and such a colored (opaque) deodorizing layer cannot be used in applications requiring transparency. Moreover, the deodorizer contained in a deodorizing layer may be unable to be used from viewpoints, such as safety and health.

JP 2006-334784 A JP 2004-25664 A JP 2002-144501 A

  The objective of this invention is providing the method of suppressing generation | occurrence | production of the odor component from an oxygen absorptive resin composition.

  The present inventors have clarified that the odor component generated by oxygen absorption in the oxygen-absorbing resin composition is a fatty acid having 1 to 7 carbon atoms mainly composed of formic acid, and the oxygen-absorbing resin composition It has been found that by using an ethylene-vinyl alcohol copolymer as the matrix resin, the generation of odorous components from the oxygen-absorbing resin composition can be suppressed without using a deodorant. Furthermore, it discovered that generation | occurrence | production of the odor component from the multilayer structure which has a layer which consists of an oxygen absorptive resin composition can be suppressed more effectively by using a deodorizing agent together. Based on these findings, further studies have been made and the present invention has been completed.

  The present invention relates to a method for suppressing the generation of odorous components from the oxygen-absorbing resin composition (A), wherein the method comprises the step of adding a compound (a) having a carbon-carbon double bond to an ethylene-vinyl alcohol copolymer. It includes a step of obtaining an oxygen-absorbing resin composition (A) by dispersing in a resin containing the polymer (b).

  In one embodiment, the said odor component is a C1-C7 fatty acid.

  In one embodiment, the fatty acid having 1 to 7 carbon atoms is formic acid.

  In another embodiment, the ethylene-vinyl alcohol copolymer (b) is an ethylene-vinyl alcohol copolymer having an ethylene content of 5 to 60 mol% and a saponification degree of 90% or more.

  In still another embodiment, the compound (a) having a carbon-carbon double bond is a thermoplastic resin having a carbon-carbon double bond substantially only in the main chain.

  In another embodiment, the method further includes the step of forming the layer (X) composed of the oxygen-absorbing resin composition (A).

  Furthermore, the present invention is a method for suppressing the generation of odor components from a multilayer structure having a layer (X) comprising the oxygen-absorbing resin composition (A), the method comprising a carbon-carbon double bond A step of obtaining an oxygen-absorbing resin composition (A) by dispersing a compound (a) having an ethylene-vinyl alcohol copolymer (b), and an oxygen-absorbing resin composition (A) And a layer (X) other than the layer (X) is laminated to obtain a multilayer structure.

  In one embodiment, layers (Y) other than the layer (X) are layers containing an adhesive resin (c).

  In a certain embodiment, layers (Y) other than the said layer (X) are layers containing a deodorizing agent (d).

  In another embodiment, the layers (Y) other than the layer (X) contain only one type of deodorant (d).

  Moreover, this invention is a multilayer structure by which generation | occurrence | production of the odor component was suppressed by the said method.

  In one embodiment, the said odor component is a C1-C7 fatty acid.

  In one embodiment, the fatty acid having 1 to 7 carbon atoms is formic acid.

  In another embodiment, the amount of formic acid generated is substantially zero.

  According to this invention, generation | occurrence | production of the odor component from an oxygen absorptive resin composition can be suppressed.

  The method for suppressing the generation of odorous components from the oxygen-absorbing resin composition (A) of the present invention is carried out by converting a compound (a) having a carbon-carbon double bond into an ethylene-vinyl alcohol copolymer (b) (hereinafter referred to as “a”). , EVOH (b) may be described) and a step of obtaining an oxygen-absorbing resin composition (A).

[Compound (a) having a carbon-carbon double bond]
The compound (a) having a carbon-carbon double bond used in the method of the present invention is not particularly limited, but in the present specification, the “carbon-carbon double bond” includes carbon-carbon contained in an aromatic ring. Double bonds are not included.

  Examples of the compound (a) having a carbon-carbon double bond include polydienes such as polybutadiene, polyisoprene, polychloroprene, poly (2-ethylbutadiene), poly (2-butylbutadiene), Examples include those polymerized at the 4-position (for example, 1,4-polybutadiene); cycloolefin ring-opening metathesis polymers (polyoctenylene, polypentenylene, polynorbornene, etc.).

  Among these, as the compound (a) having a carbon-carbon double bond, a thermoplastic resin having a carbon-carbon double bond substantially only in the main chain is preferable from the viewpoint of reducing odor. By using such a thermoplastic resin, the amount of odor components generated from the compound (a) having a carbon-carbon double bond can be reduced. Furthermore, the trace amount of odor components generated from the compound (a) having a carbon-carbon double bond is also effectively suppressed from being generated from the oxygen-absorbing resin composition (A) by using the method of the present invention. Can be done.

  Here, “substantially only having a carbon-carbon double bond in the main chain” means that the carbon-carbon double bonds existing in the main chain of the thermoplastic resin are all carbon-carbon double bonds in the molecule. The carbon-carbon double bond existing in the side chain is less than 10% of the total carbon-carbon double bond in the molecule. The proportion of carbon-carbon double bonds present in the side chain is preferably less than 7%, more preferably less than 5%.

  The compound (a) having a carbon-carbon double bond is preferably polyoctenylene from the viewpoint of oxygen absorption.

  When such a compound (a) having a carbon-carbon double bond is used as a material of the oxygen-absorbing resin composition (A), it consumes oxygen by reacting with oxygen (oxidation reaction). Generates unpleasant odor components.

  Such unpleasant odor components are low molecular weight fatty acids (fatty acids having 1 to 7 carbon atoms) such as formic acid and acetic acid, aldehydes, and the like. The method of this invention suppresses generation | occurrence | production of the C1-C7 fatty acid which has formic acid as a main component among these odor components, and suppresses especially generation | occurrence | production of the main component formic acid effectively.

[Ethylene-vinyl alcohol copolymer (EVOH) (b)]
The ethylene content and saponification degree of EVOH (b) used in the method of the present invention are not particularly limited. The ethylene content of EVOH (b) used in the method of the present invention is preferably 5 to 60 mol%, more preferably 10 to 55 mol%, still more preferably 20 to 50 mol%.

  When the ethylene content of EVOH (b) is less than 5 mol%, the resulting oxygen-absorbing resin composition (A) tends to have insufficient thermal stability, and gels and blisters are likely to occur during molding. There is a tendency. On the other hand, when the ethylene content exceeds 60 mol%, the gas barrier property tends to decrease, and at the same time, the effect of suppressing the generation of odorous components tends to decrease.

  The saponification degree of EVOH (b) used in the method of the present invention is preferably 90% or more, more preferably 95% or more, and further preferably 98% or more.

  When the saponification degree of EVOH (b) is less than 90%, the resulting oxygen-absorbing resin composition (A) tends to have insufficient thermal stability, and tends to easily generate gels and blisters during molding. It is in.

  Only one type of EVOH (b) may be used. For example, two or more types of EVOH (b) having different ethylene contents may be used in combination. When EVOH (b) is used in combination, the average value calculated from the mixing mass ratio is the ethylene content. In this case, it is preferable that the difference in ethylene content between EVOH (b) having the most distant ethylene contents is 30 mol% or less and the difference in the degree of saponification is 10% or less. 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.

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

  The oxygen-absorbing resin composition (A) may contain a resin other than EVOH (for example, polyethylene, polypropylene, polystyrene, etc.), a transition metal salt, or the like within a range that does not impair the effects of the present invention. .

[Transition metal salts]
In particular, since the oxygen-absorbing resin composition (A) contains a transition metal salt, the transition metal salt works as an oxygen absorption promoter, so that the oxygen absorption performance of the compound (a) having a carbon-carbon double bond is improved. Can do. According to the method of the present invention, the oxygen absorption performance is improved and the generation of a fatty acid having 1 to 7 carbon atoms mainly composed of formic acid which is an odor component is promoted from the compound (a) having a carbon-carbon double bond. Even if it does, since EVOH (b) is used, generation | occurrence | production of the odor component from an oxygen absorptive resin composition (A) is suppressed. Among these odor components, generation of formic acid is particularly effectively suppressed by using EVOH (b).

  Examples of transition metal salts include, but are not limited to, iron salts, nickel salts, copper salts, manganese salts, cobalt salts, rhodium salts, titanium salts, chromium salts, vanadium salts, ruthenium salts, and the like. Among these, iron salt, nickel salt, copper salt, manganese salt, and cobalt salt are preferable, manganese salt and cobalt salt are more preferable, and cobalt salt is more preferable.

  In the transition metal salt, the transition metal counter ion includes 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, capric acid, and naphthenic acid. Particularly preferred salts include cobalt 2-ethylhexanoate, cobalt neodecanoate, and cobalt stearate.

  A transition metal salt is mix | blended in the range of 0.001 mass part-0.5 mass part (10 ppm-5000 ppm) by metal conversion amount with respect to 100 mass parts of oxygen-absorbing resin compositions (A). Preferably, the transition metal salt is a metal equivalent, and ranges from 0.01 parts by weight to 0.1 parts by weight (100 to 1000 ppm), more preferably from 0.02 parts by weight to 0.08 parts by weight (200 ppm to 800 ppm). Blend in. When the blending amount of the transition metal salt is less than 0.001 part by mass (10 ppm), the resulting multilayer structure tends to have insufficient oxygen absorption performance and oxygen absorption rate. On the other hand, when the blending amount of the transition metal salt exceeds 0.5 parts by mass (5000 ppm), for example, when the oxygen-absorbing resin composition (A) and the transition metal salt are melt-kneaded, generation of decomposition gas accompanied by heat generation is generated. The formation of gels and blisters in the molded article becomes remarkable, and the processability tends to deteriorate. Furthermore, the thermal stability of the oxygen-absorbing resin composition (A) obtained by melt-kneading tends to decrease. There is also a concern that the original oxygen absorption performance of the compound (a) having a carbon-carbon double bond may be deactivated by oxidation during processing.

[Oxygen-absorbing resin composition (A)]
The oxygen-absorbing resin composition (A) is obtained by dispersing the compound (a) having a carbon-carbon double bond in a resin containing EVOH (b). The form in which the compound (a) having a carbon-carbon double bond is dispersed in a resin containing EVOH (b) is not particularly limited. For example, particles containing a compound (a) having a carbon-carbon double bond and a resin containing EVOH (b), and if necessary, compounds other than the compound (a) having a carbon-carbon double bond and EVOH (b) Examples include a form in which the components are melt-kneaded and the particles of the compound (a) having a carbon-carbon double bond are dispersed in a resin matrix containing EVOH (b).

  The compounding ratio (mass ratio) of the compound (a) having a carbon-carbon double bond and EVOH (b) is not particularly limited, and is preferably 1:99 to 30:70, more preferably 1.5: 98. It is 5-20: 80, More preferably, it is 2: 98-15: 85. When the compounding amount of the compound (a) having a carbon-carbon double bond is less than the above range, the resulting multilayer structure tends to have insufficient oxygen absorption performance and oxygen absorption rate. On the other hand, when more than the said range, it becomes the tendency for the odor component which generate | occur | produces from an oxygen absorptive resin composition (A) to increase, and an odor component may not fully be suppressed.

  The method for suppressing the generation of odorous components from the oxygen-absorbing resin composition (A) of the present invention further includes the step of forming the layer (X) comprising the oxygen-absorbing resin composition (A). May be.

  Furthermore, the method of suppressing generation | occurrence | production of the odor component from the multilayer structure which has layer (X) which consists of oxygen-absorbing-resin composition (A) of this invention is the compound (a) which has a carbon-carbon double bond. A step of obtaining an oxygen-absorbing resin composition (A) by dispersing in an ethylene-vinyl alcohol copolymer (b) -containing resin, and a layer (X) comprising the oxygen-absorbing resin composition (A) and the layer (X) A step of laminating a layer (Y) other than the layer (X) to obtain a multilayer structure.

  The layer (Y) other than the layer (X) made of the oxygen-absorbing resin composition (A) may be a layer containing a deodorant (d) described later, a layer containing an adhesive resin (c), or the like. .

[Deodorizer]
The method of the present invention can suppress the generation of the odor component without using the deodorant (d), but in order to more effectively suppress the generation of the odor component, the step of adding the deodorant (d) It may be included.

  Although it does not specifically limit as a deodorizer (d), For example, a porous inorganic particle, a surface modification metal, a hydrotalcite, etc. are mentioned.

  Examples of the porous inorganic particles include zeolite, silica gel, activated aluminum oxide, clay, diatomaceous earth, talc and the like. Among the porous inorganic particles, zeolite is preferable from the viewpoint of ease of molding and good appearance because it efficiently removes odorous components in a small amount. These porous inorganic particles may be used alone or in combination of two or more.

  Examples of the surface modified metal include a metal whose surface is modified with a hydroxyl group, and a metal whose surface is modified with an amino group. The surface-modifying metal has different components that can be effectively removed depending on the functional group modified on the surface. For example, a metal modified with a hydroxyl group is mainly effective for removing fatty acids, and a metal modified with an amino group is mainly effective for removing aldehydes. The inclusion of a metal modified with an amino group as the deodorizer (d) is preferable because not only the acid component but also the aldehyde can be efficiently removed. These surface-modifying metals may be used alone or in combination of two or more.

  Only one type of deodorizer (d) may be used, or two or more types may be used in combination. When combining two types of deodorizers (d), a combination of zeolite and a surface-modified metal is particularly preferable.

  The inventors of the present invention have described that the odor component generated by oxygen absorption by the compound (a) having a carbon-carbon double bond is a fatty acid having 1 to 7 carbon atoms mainly composed of formic acid. It has been found that odor components may not be sufficiently removed with one type of deodorant. By using the method of the present invention, it is possible to sufficiently suppress the generation of odor components, particularly formic acid, from the oxygen-absorbing resin composition (A) without using a deodorant. Furthermore, when a deodorizer is used to effectively suppress the generation of odor components, the generation of formic acid is sufficiently suppressed, so even if only one type of deodorizer is used, it is an odor component. Generation | occurrence | production of a C1-C7 fatty acid can fully be suppressed. When only one type of deodorant is used, it is particularly preferable to use zeolite or a surface-modified metal that effectively suppresses the generation of fatty acids having 2 to 7 carbon atoms.

  In the method of the present invention, the deodorizer (d) is added to a layer (Y) other than the layer (X) made of the oxygen-absorbing resin composition (A) and contains a deodorizer (d) (deodorant layer). ) Is preferably used. In the deodorizing layer, the deodorizing agent (d) is dispersed in the base resin. The base resin is not particularly limited. For example, polyolefin resins such as polyethylene (very low density, low density, linear low density, medium density, high density, etc.) and polypropylene (homopolypropylene, random polypropylene, block polypropylene, etc.) Polystyrene resins such as general-purpose polystyrene (GPPS) and high-impact polystyrene (HIPS); other α-olefin copolymers; polyamide resins, polyester resins, polyvinyl chloride resins, polyacrylonitrile resins, polyvinyl alcohol Examples thereof include gas barrier resins such as resin-based resins; and adhesive resins (c) such as modified polyolefin-based resins. Among these base resins, it is preferable to use the adhesive resin (c) from the viewpoint of reducing the lamination process.

  The mixing ratio (mass ratio) of the deodorizing agent (d) and the base resin in the deodorizing layer is not particularly limited, and preferably 0.1: 99.9 to 50:50, more preferably 0.5: 99.5. 30:70, more preferably 1:99 to 15:85. When the blending amount of the deodorizing agent (d) is less than the above range, the effect of removing the odor component by the deodorizing layer tends to be small. On the other hand, when more than the said range, there exists a tendency for the transparency of the multilayer structure obtained to fall.

[Multilayer structure]
The multilayer structure of the present invention is used as a packaging body for containers, films, pouches, and the like. When used as a package having a deodorizing layer, the deodorizing layer is located on the inner side of the layer (X) made of the oxygen-absorbing resin composition (A) in order to remove the odor generated when oxygen remaining inside is absorbed. It is preferable to arrange | position.

  The multilayer structure of the present invention preferably has other layers from the viewpoint of imparting properties such as mechanical properties, water vapor barrier properties, and further oxygen barrier properties.

  As the layer structure of the multilayer structure, the layer (X) made of the oxygen-absorbing resin composition (A) is a layer, the deodorizing layer is b layer, the gas barrier layer is c layer, and the other resin layer is d layer. Then, from the inside, a / d, d / a / d, d / d / a / d / d, d / c / a / c / d, d / d (b) / a / d (b) / d However, the present invention is not limited to these examples. In this case, d (b) indicates that both the deodorizing layer (b layer) and the other resin layer (d layer) have properties. When a plurality of d layers are provided, the type 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. The thickness structure of each layer of the multilayer structure is not particularly limited.

  As resin used for c layer which is said gas barrier layer, a polyamide-type resin, a polyester-type resin, a polyvinyl chloride-type resin, a polyacrylonitrile-type resin, a polyvinyl alcohol-type resin etc. are mentioned, for example.

  The resin used for the d layer is preferably a thermoplastic resin from the viewpoint of processability, for example, polyethylene (ultra low density, low density, linear low density, medium density, high density, etc.), polypropylene Polyolefin resins such as homopolypropylene, random polypropylene, block polypropylene, etc .; polystyrene resins such as general-purpose polystyrene (GPPS) and impact-resistant polystyrene (HIPS); other α-olefin copolymers; modified polyolefin resins, etc. And an adhesive resin (c).

  Moreover, you may add various additives to an oxygen absorptive resin composition (A) in the range which does not inhibit the effect of this invention. Examples of such additives include plasticizers, heat stabilizers (melt stabilizers), photoinitiators, UV absorbers, antistatic agents, lubricants, colorants, fillers, desiccants, fillers, pigments, dyes , Processing aids, flame retardants, anti-fogging agents, and other polymer compounds.

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

(Preparation example: Preparation of polyoctenylene)
The inside of the three-necked flask equipped with a stirrer and a thermometer was replaced with dry nitrogen. 110 parts by mass of cis-cyclooctene and 624 parts by mass of heptane in which 0.187 parts by mass of cis-4-octene were dissolved were added to a three-necked flask. Next, 0.0424 parts by mass of [1,3-bis (2,4,6-trimethylphenyl) -2-imidazolidinylidene] dichloro (phenylmethylene) (tricyclohexylphosphine) ruthenium was dissolved in 3 parts by mass of toluene. A catalyst solution was prepared. This catalyst solution was quickly added to a three-necked flask and stirred at 55 ° C. to perform ring-opening metathesis polymerization. After 1 hour, the reaction solution was analyzed by gas chromatography (manufactured by Shimadzu Corporation, GC-14B; column: manufactured by Chemicals Inspection Association, G-100) to confirm the disappearance of cis-cyclooctene. Next, 1.08 parts by mass of ethyl vinyl ether was added to the three-necked flask, and the mixture was further stirred for 10 minutes.

  200 parts by mass of water was added to the obtained reaction solution, and the mixture was stirred at 40 ° C. for 30 minutes. Subsequently, it left still at 40 degreeC for 1 hour, and after liquid separation, the water layer was removed. 100 parts by mass of water was again added to the remaining liquid, and the mixed liquid was stirred at 45 ° C. for 30 minutes. Subsequently, it left still at 40 degreeC for 1 hour, and after liquid separation, the water layer was removed. Subsequently, heptane was distilled off from the remaining liquid under reduced pressure, and the resulting solid was dried at 1 Pa and 100 ° C. for 6 hours using a vacuum dryer, and the weight average molecular weight (Mw) was 142,000 and the molecular weight was 1000 or less. Thus, 102.1 parts by mass (yield 92%) of a polymer having an oligomer ratio of 9.2% by mass 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%.

  The obtained polymer was crushed to about 1 mm square and added to a separable flask equipped with a stirrer, a reflux tube and a thermometer. Next, 300 parts by mass of acetone was added to the separable flask, and the mixture was stirred at 40 ° C. for 3 hours. Acetone was removed by decantation. Again, 300 parts by mass of acetone was added to the separable flask, and the mixture was stirred at 40 ° C. for 3 hours. Acetone was removed by decantation. The remaining acetone was distilled off under reduced pressure, and the resulting solid was dried at 1 Pa and 100 ° C. for 6 hours using a vacuum dryer. The weight average molecular weight (Mw) was 150,000, the number average molecular weight was 37000, 99 parts by mass of polyoctenylene having a ratio of oligomers having a molecular weight of 1000 or less of 3.1% by mass was obtained.

Example 1
Preparation of 92 parts by mass of EVOH (b-1) having an ethylene content of 32 mol%, a saponification degree of 99.8%, and a melt flow rate (MFR) of 1.6 g / 10 min (under 190 ° C. and 2160 g load) 8 parts by mass of polyoctenylene obtained in the example and 0.4242 parts by mass of cobalt stearate (II) (400 ppm in terms of metal) were added to a 25 mmφ twin-screw extruder (manufactured by Toyo Seiki Co., Ltd .: LABO PLATOTOM MODEL 15C300). I put it in. Extrusion was performed at 210 ° C. under the conditions of a screw rotational speed of 100 rpm and an extruded resin amount of 4 kg / hour to obtain oxygen-absorbing resin composition pellets.

  Next, the obtained oxygen-absorbing resin composition pellets, polypropylene (PP) (Novatech EA7A manufactured by Nippon Polypropylene Co., Ltd.), and adhesive resin (AD) (AdmerQF500 manufactured by Mitsui Chemicals, Inc.) are melt-kneaded with separate extruders. did. Subsequently, a multilayer film of 3 types and 5 layers (PP layer / AD layer / oxygen absorption layer / AD layer / PP layer = 200 μm / 15 μm / 25 μm / 15 μm / 200 μm) was formed using a coextrusion apparatus.

  The obtained multilayer film was cut so that the oxygen absorption layer was 50 mg, and sealed in a 20 mL vial. The vial containing the multilayer film was allowed to stand at 35 ° C. under 100% RH for 7 days, and then the oxygen absorption amount and odor component generation amount were measured, and odor sensory evaluation was performed. The results are shown in Table 1.

<Oxygen absorption amount>
Using an oxygen concentration meter (Iijima Electronics Co., Ltd. Food Micro-Oxygen Analyzer IS-300), the oxygen concentration in the vial before and after standing was measured, and the amount of oxygen absorbed per unit mass of the oxygen absorbing layer was determined. It was.

<Odor component generation amount>
Using GC-MS (POLALISQ Trace GC manufactured by Thermo Electron Corporation), the concentration of odor components in the vial after standing was measured, and the amount of odor components generated per unit mass of the oxygen absorbing layer was determined. In addition, the C3 fatty acid was not detected.

<Sensory evaluation of odor>
Five subjects were allowed to smell the odor in the vial after standing, and judged according to the following evaluation criteria to obtain an average value.
0: Odorless 1: Slight odor that cannot be distinguished from what odor (detection threshold)
2: A weak odor that can be used to determine what kind of odor (recognition threshold)
3: Medium odor that can be felt normally 4: Strong odor 5: Unusable odor

(Example 2)
96 parts by mass of EVOH (b-2) having an ethylene content of 27 mol%, a saponification degree of 99.8%, and an MFR of 4.0 g / 10 min (210 ° C., 2160 g under load) was obtained in the preparation example. A multilayer film was formed in the same procedure as in Example 1, except that 4 parts by weight of polyoctenylene and 0.2121 parts by weight of cobalt stearate (II) (200 ppm in terms of metal) were used. The oxygen absorption amount and odor component generation amount were measured and the odor sensory evaluation was performed in the same procedure as described above. The results are shown in Table 1.

(Example 3)
EVOH (Kuraray Co., Ltd. Eval SP521) (EVOH (b-3)) 98 parts by mass, polyoctenylene 2 parts by mass obtained in Preparation Example, cobalt stearate (II) 0.2121 parts by mass (in metal equivalent) 200 ppm), a multilayer film was formed in the same procedure as in Example 1, and the oxygen absorption amount and odor component generation amount were measured in the same procedure as in Example 1, and the sensory evaluation of odor was performed. went. The results are shown in Table 1.

Example 4
99 parts by mass of an adhesive resin (AdmerQF500) and 1 part by mass of zeolite (ABSENTS3000 manufactured by Union Showa Co., Ltd.) as a deodorizer were charged into the 25 mmφ twin screw extruder. Extrusion was performed at 200 ° C. under the conditions of a screw speed of 100 rpm and an extruded resin amount of 4 kg / hour to prepare resin composition pellets containing a deodorant.

  A multilayer film was formed in the same procedure as in Example 3 except that the resin composition pellets containing this deodorant were used as the adhesive resin, and the oxygen absorption amount and odor were determined in the same manner as in Example 3. Measurement of component generation amount and sensory evaluation of odor were performed. The results are shown in Table 1.

(Example 5)
A multilayer film was formed in the same procedure as in Example 4 except that 96 parts by mass of an adhesive resin (AdmerQF500) in the deodorizer layer and 4 parts by mass of zeolite (ABSENTS3000) were used as the deodorizer. In the same procedure as in No. 4, the oxygen absorption amount and odor component generation amount were measured, and the sensory evaluation of odor was performed. The results are shown in Table 1.

(Comparative Example 1)
A multilayer film was formed in the same procedure as in Example 2 except that polyoctenylene was not used, and the oxygen absorption amount and odor component generation amount were measured and the sensory evaluation of odor was performed in the same procedure as in Example 2. It was. The results are shown in Table 1.

(Comparative Example 2)
A multilayer film was formed in the same procedure as in Example 1 except that 92 parts by mass of polyethylene (PE) (Novatec NF325N manufactured by Nippon Polyethylene Co., Ltd.) was used instead of 92 parts by mass of EVOH (b-1). The oxygen absorption amount and odor component generation amount were measured in the same procedure as in Example 1, and the sensory evaluation of odor was performed. The results are shown in Table 1.

  As shown in Table 1, the multilayer films of Examples 1 to 3 containing EVOH and polyoctenylene sufficiently suppressed (substantially 0) the generation of formic acid, which is an odor component, without using a deodorizing layer. Recognize. Further, it can be seen that Examples 4 and 5 including the deodorizing layer sufficiently suppressed the generation of fatty acids (valeric acid, hexanoic acid, heptanoic acid), which are odor components other than formic acid.

  ADVANTAGE OF THE INVENTION According to this invention, the method of suppressing generation | occurrence | production of the odor component from an oxygen absorptive resin composition can be provided. Therefore, the method of the present invention is useful in the field of packaging foods, beverages, pharmaceuticals, cosmetics and the like.

Claims (14)

A method for suppressing the generation of odorous components from the oxygen-absorbing resin composition (A),
A method comprising a step of obtaining an oxygen-absorbing resin composition (A) by dispersing a compound (a) having a carbon-carbon double bond in a resin containing an ethylene-vinyl alcohol copolymer (b).   The method according to claim 1, wherein the odor component is a fatty acid having 1 to 7 carbon atoms.   The method according to claim 2, wherein the fatty acid having 1 to 7 carbon atoms is formic acid.   The ethylene-vinyl alcohol copolymer (b) according to any one of claims 1 to 3, wherein the ethylene-vinyl alcohol copolymer (b) is an ethylene-vinyl alcohol copolymer having an ethylene content of 5 to 60 mol% and a saponification degree of 90% or more. The method described.   The method according to any one of claims 1 to 4, wherein the compound (a) having a carbon-carbon double bond is a thermoplastic resin having a carbon-carbon double bond substantially only in the main chain. .   The method according to any one of claims 1 to 5, further comprising the step of forming a layer (X) comprising the oxygen-absorbing resin composition (A). A method for suppressing the generation of odorous components from a multilayer structure having a layer (X) comprising an oxygen-absorbing resin composition (A),
A step of obtaining an oxygen-absorbing resin composition (A) by dispersing a compound (a) having a carbon-carbon double bond in a resin containing an ethylene-vinyl alcohol copolymer (b), and an oxygen-absorbing resin A method comprising a step of laminating a layer (X) comprising the composition (A) and a layer (Y) other than the layer (X) to obtain a multilayer structure.   The method according to claim 7, wherein the layer (Y) other than the layer (X) is a layer containing an adhesive resin (c).   The method according to claim 7 or 8, wherein the layer (Y) other than the layer (X) is a layer containing a deodorizing agent (d).   The method of Claim 9 that layers (Y) other than the said layer (X) contain only one type of deodorizing agent (d).   The multilayer structure by which generation | occurrence | production of the odor component was suppressed by the method of any one of Claims 7-10.   The multilayer structure according to claim 11, wherein the odor component is a fatty acid having 1 to 7 carbon atoms.   The multilayer structure according to claim 12, wherein the fatty acid having 1 to 7 carbon atoms is formic acid.   The multilayer structure according to claim 13, wherein the amount of formic acid generated is substantially zero.