JPH1180555A - Oxygen-absorbing resin composition and packaging container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition capable of considerably suppressing the oxygen concentration in the containers made thereof to low levels not only at the initial stage but also after the lapse of days, and useful for packaging containers or the like, by including a thermoplastic resin and a specific iron- based oxygen scavenger in specified proportions. SOLUTION: This composition is obtained by including (A) 100 pts.wt. of a thermoplastic resin (pref. olefin-based resin) and (B) 1-100 pts.wt. of an iron- based oxygen scavenger >=0.5 m<2> /g in specific surface area, <=3 g/cc in apparent density and 1-50 μm in average particle size, composed of (1) iron powder and (2) 0.1-30 pts.wt., based on 100 pts.wt. of the component (1), of such a metal salt as to be <=pH 1.0 (20 deg.C) in the form of a saturated aqueous solution (pref. group IIIB IVB or VIII metal halide, esp. iron chloride, tin chloride).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oxygen-absorbing resin composition and a packaging container using the same, and more particularly, to an oxygen-absorbing resin composition having a remarkably improved oxygen absorption rate in a resin. Articles and packaging containers.

[0002]

2. Description of the Related Art Conventionally, metal cans, glass bottles, various plastic containers, and the like have been used as packaging containers. However, plastic containers have been used for various purposes in terms of lightness, impact resistance, and cost. I have. However, while oxygen permeation through the container wall is zero in metal cans and glass bottles, oxygen permeation through the container wall occurs in a non-negligible order in the case of plastic containers, and the preservability of the contents is low. Is a problem.

[0003] Conventionally, it has been known for a long time to incorporate an oxygen absorber or a deoxidizer into a resin in order to capture oxygen remaining in the container or to capture oxygen permeating the container wall. JP-A-57-194959 discloses a container lid comprising a container lid shell and a sealing gasket provided in a sealing portion of the shell, wherein the sealing gasket contains a solid oxygen absorbent. A container lid is described. In addition, Japanese Patent Application Laid-Open No.
No. 4 discloses that the oxygen permeation coefficient at 20 ° C. and 0% RH is 10 ⁻¹² cc · cm / cm ² · sec · cmHg or less, and the water adsorption at 20 ° C. and 100% RH is 0.5% by weight or more. A plastic multilayer container comprising a layer of a resin composition in which a gas barrier resin is mixed with a deoxidizer and a water absorbing agent is described.

[0004] It is already known to use iron powder coated on its surface with an oxidation accelerator or the like as an oxygen absorber.
JP-A-53-14185 discloses that a metal powder is coated with a metal halide, the coating amount of the metal halide is 0.001 to 5 parts with respect to 100 parts of the metal powder, and the water content is Oxygen absorbents which are less than 1% by weight of the total are described.

[0005] It is also known to blend an oxygen absorber in which an oxidation promoter is preliminarily coated on iron powder into a resin. Japanese Patent Application Laid-Open No. 57-194959 mentioned above discloses a metal halide as an oxygen absorber. It is described that iron powder or the like coated with, can be used. JP-A-2-72851 describes a microporous film containing an oxygen-absorbing composition obtained by stretching a thermoplastic resin film in which the oxygen-absorbing composition is dispersed in a film. It describes that an iron powder having a surface coated with a metal halide salt is used as an agent composition. Further, JP-A-6-170
No. 940 discloses an iron powder 30 to 8 having a primary particle size of 0.01 to 20 μm and an aggregated particle size of 5 to 200 μm.
After kneading a mixture of 5 parts by weight and an aqueous electrolyte solution and 15 to 70 parts by weight of a thermoplastic resin, and processing the sheet,
There is described a method for producing an oxygen-absorbing sheet, wherein the sheet is stretched at least in a uniaxial direction at a magnification of 1.5 to 9 times.

[0006]

In a known resin composition containing an oxygen absorbent, an oxidation promoter such as a metal halide adsorbs water, and the oxygen absorbent such as iron powder is oxidized in the presence of the water. As a result, oxygen in the container or oxygen passing through the vessel wall is absorbed.

However, in the known oxygen-absorbing agent-containing resin composition, even if the oxygen absorbing agent used is outside the resin, the oxygen absorbing speed is excellent, but in the state of a molded product mixed with the resin, the oxygen absorbing speed is low. Slow, as a result, it takes a long time to absorb oxygen in the container,
The oxygen absorption rate was not yet sufficiently high, and the content preservability was not yet sufficiently satisfactory.

Accordingly, an object of the present invention is to provide an oxygen-absorbing agent-containing resin composition which is blended with a resin and has a significantly improved oxygen absorption rate even in a molded state, and a packaging container formed from the resin composition. To offer. Another object of the present invention is to provide a sealed packaging container capable of suppressing the oxygen concentration in the container not only after a lapse of days but also in the initial stage.

[0009]

According to the present invention, (A)
Thermoplastic resin, and (B) (B-1) iron powder and (B-
2) An iron-based oxygen scavenger composed of a metal salt having a pH (25 ° C.) of 1.0 or less as a saturated aqueous solution, and an iron-based oxygen scavenger (B) per 100 parts by weight of the thermoplastic resin (A). ) Is 1 to 100 parts by weight and iron powder (B-1) 100
An oxygen-absorbing resin composition is provided, wherein the metal salt (B-2) is present in an amount of 0.1 to 30 parts by weight per part by weight. In the oxygen-absorbing resin composition of the present invention, 1. the thermoplastic resin is an olefin resin; It is preferable that the metal salt is a halide of a metal of Group 3B, 4B or 8 of the periodic table, particularly iron chloride or tin chloride. According to the present invention, in a packaging container provided with a layer of an oxygen-absorbing resin composition, the oxygen-absorbing resin composition is (A) a thermoplastic resin, and (B) (B)
-1) pH as iron powder and (B-2) saturated aqueous solution
(25 ° C.) is an iron-based oxygen scavenger comprising a metal salt having a value of 1.0 or less, and 1 to 100 parts by weight of the iron-based oxygen scavenger (B) per 100 parts by weight of the thermoplastic resin (A) and iron The metal salt (B-2) is contained in an amount of 0.1 to 100 parts by weight of the powder (B-1).
A packaging container is provided which is a resin composition present in an amount of 1 to 30 parts by weight.

[0010]

DETAILED DESCRIPTION OF THE INVENTION

[Action] In the present invention, among various metal salts, a metal salt having a pH (25 ° C.) of 1.0 or less as a saturated aqueous solution, preferably a Group 3B, Group 4B or Group 8B of the periodic table.
A feature is that halides of group metals, most preferably iron chloride and tin chloride, are selected and combined with iron powder in a thermoplastic resin. According to the present invention, by selecting the above-mentioned metal salt, it becomes possible to remarkably increase the oxygen absorption rate in a state of being mixed with the resin and molded.

The most commonly used water-soluble metal salt for activating the iron-based oxygen scavenger is sodium chloride (sodium chloride).
Of course, it is neutral or near neutral, and even if this salt is blended in a thermoplastic resin together with iron powder, its oxygen absorption rate is 4 times lower than the oxygen absorption rate in a state where it is not blended with the resin. 1 /
It is as low as the following (see Table 1 described later). On the other hand, when a saturated aqueous solution is used as the metal salt,
When a metal salt having a temperature (25 ° C.) of 1.0 or less, in particular, a halide of a metal of Groups 3B, 4B or 8 of the periodic table is selected and blended in a resin, the oxygen absorption rate is reduced It is possible to improve it more than twice as compared with the case of the above, which is an unexpected effect according to the present invention.

Further, referring to Table 1, it can be understood that it is critical that the pH of the saturated aqueous solution is 1.0 or less in order to increase the oxygen absorption rate in the state of being mixed with the resin.

[0013] As shown in Fig. 1, the residual oxygen concentration in the container when actually used as a container is, as shown in Fig. 1, when the metal salt specified in the present invention is used, when the common salt is used. In comparison, it is clear that the initial oxygen absorption rate can be extremely high and the final oxygen residual concentration can be maintained at an extremely low level.

In the present invention, the fact that a metal salt having a pH (25 ° C.) of not more than 1.0 as a saturated aqueous solution significantly increases the oxygen absorption rate in a state of being mixed in a resin has been confirmed by many experiments. As a result, it was found as a phenomenon, the reason for which is not always clear enough,
It is considered as follows. That is, the metal salt used in the present invention has a very high ability to activate the iron powder buried in the resin, which includes hydrogen ions generated when the metal salt comes into contact with moisture, in the resin. This is probably because the mobility is relatively high, which has helped to activate the iron powder.

In the present invention, the thermoplastic resin (A) 1
1 to 100 parts by weight of the iron-based oxygen scavenger (B)
Parts by weight, especially 2 to 40 parts by weight, and metal salt (B-2) per 100 parts by weight of iron powder (B-1)
It is also important that is present in an amount of 0.1 to 30 parts by weight, especially 0.5 to 10 parts by weight. When the amount of the iron-based oxygen scavenger (B) is below the above range, the oxygen absorbing ability is insufficient. On the other hand, when the amount exceeds the above range, the moldability of the resin composition is reduced, The mechanical strength of the composition tends to decrease. On the other hand, when the amount of the metal salt (B-2) is below the above range, the oxygen absorption rate tends to decrease as compared with the case where it is in the range of the present invention. It is not preferable because the water resistance and other physical properties of the whole product are deteriorated.

[Iron powder] As iron powder for iron-based oxygen scavenger,
What is generally called reduced iron powder is used. Reduced iron powder
Is generally obtained in the production process of iron compounds such as iron ore
Using a furnace with a mill scale with a reducing agent (for example, coke)
Finish reduction in hydrogen gas or decomposed ammonia gas
Is obtained by performing a finishing heat treatment. Iron compound
For example, FeOOH, Fe (OH)_Three, FeC
l_Three, FeSO_FourAnd iron oxide. As iron oxide
For example, pyrite, magnetite, limonite, siderite, pyrite, α-
Fe_TwoO _Three, Γ-Fe_TwoO_Three, Fe_ThreeO_FourIs mentioned
You. Other than coke, reducing ammonia
Any reducing gas may be used. As a furnace, for example,
Furnace, rotary kiln, tunnel kiln
You. Finish reduction or finishing process is 400 ~ 900 ℃
Perform at about the temperature. The reduction firing of iron compounds is generally carried out at 40
This is performed at a temperature of about 0 to 1300 ° C.

The production of iron powder is not limited to the above-mentioned reduction method.
It can also be produced by electrolytic deposition of iron from an aqueous solution containing iron ions, spraying of molten iron into a non-oxidizing atmosphere, grinding of pure metallic iron, or steam pyrolysis of carbonyl iron.

From the viewpoint of reactivity with oxygen, the iron powder preferably has high activity and the amount of metallic iron is preferably 70% or more. Further, from the viewpoint of preventing the deterioration of the resin and improving the flavor retention, the content of copper relative to iron is 1%.
It is preferable that the content of sulfur is 50 ppm or less and the content of sulfur is 500 ppm or less.

The iron-based oxygen scavenger particles used in the present invention have a particle size of 0.1.
It preferably has a specific surface area of 5 m ² / g or more and an apparent density of 3 g / cc or less. Specific surface area is 0.5m ² /
g, or when the apparent density exceeds ³ g / cm ³ , the oxygen absorption rate tends to decrease and the residual oxygen amount in the container tends to increase as compared with the case where the apparent density is within the above range. This means that the absorption of oxygen in the oxygen-absorbing agent-containing resin composition is, after all, performed through the surface of the iron-based oxygen-absorbing particles. It is presumed that it is difficult to effectively absorb oxygen from the surface.

The iron-based oxygen scavenger particles used in the present invention preferably have an average particle diameter of 1 to 50 μm as measured by a laser scattering method. The iron-based oxygen scavenger particles having an average particle diameter within the above range have excellent dispersibility in a thermoplastic resin and also have excellent oxygen absorbability.

[Metal Salt] As described above, the metal salt used in the present invention has a pH (25
C) is 1.0 or less. Examples of the metal include metals of Groups 3B, 4B, and 8 of the periodic table, and more specifically, aluminum, tin, iron, and the like. Preferably, the metal salt is a halide, especially a chloride, such as iron chloride (FeCl ₃ ), tin chloride (SnC).
l ₂ ) is most preferred.

Although not necessary, other water-soluble or water-absorbing substances can be used in combination. Specific examples include sodium chloride, calcium chloride, zinc chloride, ammonium chloride, ammonium sulfate, sodium sulfate, magnesium sulfate, disodium hydrogen phosphate, sodium diphosphate, potassium carbonate, sodium nitrate, calcium oxide, calcium sulfate, hydrogen carbonate sodium,
Examples include sodium carbonate, molecular sieve, alumina, silica gel and the like.

If desired, an inorganic compound, an organic compound, or a polymer can be used in combination as an oxidation promoter. Examples of the compound include glucose, fructose, sucrose, gelatin, modified casein, modified starch, tragacanth gum, and the like.
Polyvinyl alcohol, CMC, sodium polyacrylate, sodium alginate, ascorbic acid, sodium ascorbate, polyethylene oxide, polyacrylamide, polyoxyethylene, EDTA, ED
TA-2Na, EDTA-4Na and the like. These oxidation promoters may be incorporated into the thermoplastic resin in the form of oxygen scavenger particles, or may be incorporated into the resin separately from the oxygen scavenger particles. Needless to say, in the present invention, a plurality of oxidation promoters or catalysts can be used in combination.

[Composite oxygen scavenger] In the present invention, the iron powder and the metal salt are blended in the thermoplastic resin in the above-described ratio.
Iron powder and metal salt can be separately compounded in a thermoplastic resin, but in general, iron powder and metal salt are previously compounded,
It is preferable to blend this blended composition with a thermoplastic resin.

In this deoxidizer, the iron powder (B-1) and the metal salt (B-2) are in a ratio of 100: 0.1 to 100: 3.
It is preferable to blend at a weight ratio of 0, particularly 100: 0.5 to 100: 10. When the amount ratio of the metal salt falls below this range, the oxygen absorption rate tends to decrease as compared with the case where the ratio is within the above range. Water resistance and mechanical properties tend to be lower than those of

In the present invention, the blending of the iron powder and the metal salt can be performed by dry blending using a V-type blender, a conical blender, a spar mixer, a Henschel mixer, or the like. Further, a metal salt can be fixedly coated on the surface of the iron powder, and the fixed coating is performed by dry milling the iron powder and the metal salt powder. The end point of the dry milling can be known by the fact that free solid particles of the metal salt cannot be confirmed by an electron microscope. For dry milling, a vibration mill,
A ball mill, a tube mill, a super mixer, or the like can be used. In addition, a metal salt can be wet-coated on the surface of the iron powder, and the wet coating is performed by spraying an aqueous solution of a metal salt or an organic solvent (for example, ethanol, acetone, ether) solution onto the iron powder, or impregnating the iron powder, This is done by removing the solvent. The oxygen scavenger particles obtained after dry milling or wet coating are:
Although not generally necessary, sieving, air classification, etc.
The fine powder of the free metal salt may be separated and removed.

[Oxygen-Absorbing Resin Composition] According to the present invention, 1 to 100 parts by weight of the iron-based deoxidizer (b) is added to 100 parts by weight of the thermoplastic resin (A). The metal salt is added in an amount of 0.1 to 30 parts by weight.

Examples of the thermoplastic resin include low density polyethylene, linear low density polyethylene (LLDPE), high density polyethylene, polypropylene, poly 1-butene,
Α such as poly 4-methyl-1-pentene or ethylene, propylene, 1-butene, 4-methyl-1-pentene, etc.
Polyolefins such as random or block copolymers of olefins, ethylene / vinyl acetate copolymers,
Ethylene-vinyl alcohol copolymer, ethylene-vinyl compound copolymer such as ethylene-vinyl chloride copolymer,
Polystyrene, acrylonitrile-styrene copolymer,
ABS, styrene resins such as α-methylstyrene / styrene copolymer, polyvinyl chloride, polyvinylidene chloride,
Polyvinyl chloride / vinylidene chloride copolymer, polyvinyl compounds such as polymethyl acrylate, polymethyl methacrylate, nylon 6, nylon 6-6, nylon 6-10,
The resin may be any of polyamide such as nylon 11 and nylon 12, thermoplastic polyester such as polyethylene terephthalate and polybutylene terephthalate, polycarbonate, polyphenylene oxide and the like, or a mixture thereof.

The thermoplastic resin containing the oxygen scavenger preferably has oxygen permeability from the viewpoint of rapidly consuming oxygen, and from this viewpoint, olefin resins are particularly suitable. On the other hand, olefin-based resins have low moisture retention and cause swelling of the resin layer. However, by using the above-described oxygen absorber, it is possible to smoothly supply water necessary for oxygen absorption. Can be. In addition, the thermoplastic resin containing the oxygen scavenger preferably has low oxygen permeability in order to maintain the barrier properties over a long period of time, and from this viewpoint, it is preferable to use a copolymer of ethylene / vinyl alcohol or polyethylene. Terephthalate resins are suitable.

In the present invention, a blend of a plurality of substantially incompatible thermoplastic resins or elastomers may be used as a resin matrix containing the oxygen scavenger.
It is particularly preferable from the viewpoint of improving appearance characteristics.

Here, as the thermoplastic elastomer, for example, ethylene-propylene rubber (EPR), ethylene-propylene-diene rubber (EPDM), thermoplastic elastomer such as styrene-butadiene-styrene block copolymer, styrene-isoprene- Styrene block copolymer, hydrogenated styrene-butadiene-styrene block copolymer, hydrogenated styrene-isoprene-styrene block copolymer, hydrogenated butadiene-isoprene block copolymer, nitrile-butadiene rubber (N
(BR), styrene-butadiene rubber (SBR), chloroprene rubber (CR), polybutadiene (BR), polyisoprene (IIB), butyl rubber, natural rubber, thermoplastic polyurethane, silicone rubber, acrylic rubber, and the like. Among these, hydrocarbon elastomers, particularly EPR and EPDM, are preferred.

In the present invention, the combination of thermoplastic resins and elastomers which are incompatible with each other is not limited to these, but is, for example, propylene-based polymer / ethylene-based polymer, polyamide / olefin-based resin, polyamide / styrene-based resin. Resin, polyamide / ABS resin, polyethylene terephthalate / polybutylene terephthalate, polycarbonate / polystyrene resin, polyester resin / olefin resin, polycarbonate / polyester resin and the like.

Easy dispersing of the oxygen scavenger and thermoforming;
A particularly preferred resin combination is a combination of a crystalline propylene polymer and an ethylene polymer. As the crystalline propylene polymer, a random or block copolymer containing 1 to 20% by weight, especially 2 to 15% by weight of ethylene, in addition to homopolypropylene, is used. These polypropylenes may have an isotactic structure or a syndiotactic structure.

As the ethylene polymer, high density polyethylene (HDPE), medium density polyethylene (MDP)
E), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), ethylene and other olefins such as propylene, butene-1, pentene-1, hexene-1, 4-methylpentene-1, octene- 1,
At least one copolymer such as decene-1; ethylene-
Examples include a vinyl acetate copolymer, an ethylene-acrylate copolymer, and an ionomer.

The ratio between one resin and the other resin in the composite resin matrix can be varied in a wide range, but the weight ratio is 100: 1 to 1: 1, especially 5: 1.
It is preferably in the range of 0: 1 to 3: 2.

In the composite resin matrix, a compatibilizer can be blended in order to adjust the degree of dispersion between the resin and the elastomer. What is a compatibilizer?
A block copolymer or a graft copolymer having the same components as the polymers A and B to be blended; and a molecular mixture with one of the polymers A and B to be blended. A block copolymer or a graft copolymer having three components; a graft copolymer of two polymers compatible only with one of the polymers A and B to be blended;

Focusing on the function of the compatibilizer, there are two types: a non-reactive compatibilizer and a reactive compatibilizer.
Examples of the former include styrene-ethylene-butadiene block copolymer, polyethylene-polymethyl methacrylate block copolymer, polyethylene-polystyrene block copolymer, and the like.Examples of the latter include a maleic anhydride-modified olefin-based resin, Particularly, there are maleic anhydride-grafted polypropylene and polyethylene, styrene-maleic anhydride copolymer, ethylene-glycidyl methacrylate copolymer, ethylene-acrylate ester-maleic anhydride copolymer, styrene-glycidyl methacrylate copolymer and the like.

These compatibilizers can be present in the resin matrix in an amount of 1 to 20% by weight, especially 2 to 10% by weight.

The mixing of the oxygen scavenger and the resin matrix is as follows:
So-called dry blending or melt blending may be used. In order to disperse the oxygen scavenger well, a resin composition (masterbatch) containing a high concentration of oxygen scavenger is manufactured, and this masterbatch is blended with the resin matrix. You can also.

[Packaging Container] The oxygen-absorbing packaging container of the present invention may have any layer constitution as long as the oxygen-containing thermoplastic resin layer is provided on the vessel wall. Generally, it is desirable to laminate a thermoplastic resin layer containing no oxygen absorber on both sides of the resin composition containing the oxygen absorber from the viewpoint of the appearance characteristics of the container and the sanitary characteristics of the contents.

In FIG. 2, which shows an example of the multilayer structure of the packaging container of the present invention, the container wall 1 has a first intermediate layer made of an outer layer 2 of a moisture-resistant thermoplastic resin, an adhesive resin layer 3a, and a gas barrier resin. It comprises a layer 4, an adhesive resin layer 3b, a second intermediate layer 5 made of a resin composition containing a deoxidizer, and an inner layer 6 of a moisture-resistant thermoplastic resin. The second intermediate layer 5 is composed of a thermoplastic resin layer containing a deoxidizing agent. Even if the thermoplastic resin is made of a resin having a single composition, a plurality of substantially incompatible thermoplastic resins or It may be made of an elastomer. This second intermediate layer is a gas barrier resin layer 4
It should be noted that it is provided more inside.

In FIG. 3, which shows another example of the multilayer structure of the packaging container of the present invention, the container wall 1 has an outer layer 2 of a moisture-resistant thermoplastic resin, an adhesive resin layer 3a, and a first layer made of a gas barrier resin. Intermediate layer 4, adhesive resin layer 3b, second intermediate layer 5 made of a resin composition containing an oxygen scavenger, third intermediate layer 7 made of a resin composition containing an adsorbent deodorant, and It consists of an inner layer 6 of a moisture resistant thermoplastic resin. The oxygen absorber and the adsorptive deodorant are separately compounded in the second intermediate layer 5 and the third intermediate layer 7, respectively, and from the outside, the gas barrier resin layer 4, the oxygen absorber layer 5, and the adsorbent deodorant. It will be understood that the layer has a sex deodorant layer 7.

As the thermoplastic resin layers provided on both sides of the oxygen-absorbing agent-containing resin layer, moisture-resistant resins (low water-absorbing resins), particularly
The water absorption measured by ASTM D 570 is 0.5% or less, especially 0.1%.
Less than 1% thermoplastic resin is suitable. Typical examples are low-, medium- or high-density polyethylene, isotactic polypropylene, ethylene-propylene copolymer, polybutene-1, 4-methyl-1-pentene, ethylene-butene-1 copolymer, propylene. -Butene-1
Olefinic resins such as copolymers, ethylene-propylene-butene-1 copolymers, ethylene-vinyl acetate copolymers, ionically crosslinked olefin copolymers (ionomers) and blends thereof, and further polystyrene , Styrene-butadiene copolymer, styrene-
Styrene resins such as isoprene copolymers and ABS resins, and thermoplastic polyesters and polycarbonates such as polyethylene phthalate and polytetramethylene terephthalate can also be used. Among these, from the viewpoint of hygiene, olefin resins are preferred, and from the viewpoint of heat resistance,
Propylene resins are preferred.

In the packaging container of the present invention, as the gas barrier resin optionally used, a thermoplastic resin having a low oxygen permeability coefficient and capable of being thermoformed is used. The most suitable example of the gas barrier resin can include an ethylene-vinyl alcohol copolymer, for example,
Ethylene content of 20 to 60 mol%, especially 25 to 5
A saponified copolymer obtained by saponifying an ethylene-vinyl acetate copolymer of 0 mol% so as to have a saponification degree of 96 mol% or more, particularly 99 mol% or more is used.
This saponified ethylene-vinyl alcohol copolymer is
It should have a molecular weight sufficient to form a film and is generally greater than or equal to 0.01 dL / g, especially 0.05 dL, as measured at 30 ° C. in a 85:15 phenol: water mixture by weight.
It is desirable to have a viscosity of at least / g.

Other examples of the gas barrier resin having the above-mentioned properties include polyamides having an amide group number of 5 to 50, particularly 6 to 20, per 100 carbon atoms; 6, nylon 6,6, nylon 6 / 6,6 copolymer, metaxylylene adipamide, nylon 6,10, nylon 11, nylon 12, nylon 13, and the like. These polyamides should also have a molecular weight sufficient to form a film, and
It is desirable that the relative viscosity (ηrel) measured at a concentration of 1.0 g / dL and a temperature of 30 ° C. is 1.1 or more, particularly 1.5 or more. In addition, as shown in FIG. 2, these gas barrier resins can be provided so as to be adjacent to the oxygen-absorbing agent-containing resin layer.

As in the case of the ethylene-vinyl alcohol copolymer, there is a case where sufficient adhesiveness cannot be obtained when laminating between the gas barrier resin and the moisture-resistant thermoplastic resin to be used. Interpose an adhesive resin layer between them.

Examples of such an adhesive resin include carboxylic acid, carboxylic anhydride, and carboxylic acid. In the main chain or side chain, from 1 to 700 milliequivalent (meq) / 100 g resin, especially from 10 to 500 meq
/ 100 g of thermoplastic resin. Suitable 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, copolymer One or a combination of two or more such as a polymerized polyester and a copolymerized polyamide.
These resins are useful for lamination by coextrusion or sandwich lamination. In addition, a thermosetting adhesive resin such as an isocyanate-based or epoxy-based resin is used for bonding and laminating the gas barrier resin film and the moisture-resistant resin film formed in advance. Further, a metal foil such as an aluminum foil or a steel foil can be used instead of the gas barrier resin.

The oxygen-absorbing agent-containing resin layer varies depending on the amount of oxygen allowed in the container and the shape of the container, but preferably has a thickness of 5 to 200 μm, especially 10 to 150 μm.

On the other hand, the moisture-resistant resin layer provided on both sides of the above-mentioned oxygen-absorbing agent-containing resin layer is generally 10 to 500 μm, particularly 20 to 200 μm, and 0.05 to 100 times the thickness of the intermediate layer, especially 0.5 to 100 times. It is preferable to have ten times the thickness. In addition, the thickness of the inner layer and the outer layer may be equal, and one of the inner layer and the outer layer may be configured to be thicker than the other layer. Further, the thickness of the gas barrier resin layer is generally 5 to 100 μm, particularly 10 to 50 μm.
It is preferable to have a thickness of m.

The packaging container of the present invention can be manufactured by a method known per se. For example, this container can be manufactured by multi-layer coextrusion, and after melting and kneading a resin or a resin composition with an extruder corresponding to each resin layer, a predetermined shape is passed through a multi-layered die such as a T-die or a circular die. Extrude into Further, after the resin or the resin composition is melt-kneaded by an injection machine corresponding to each resin layer, the resin or the resin composition is co-injected or sequentially injected into an injection mold to produce a multilayer container or a preform for the container. Further, a lamination method such as dry lamination, sandwich lamination, and extrusion coating may be employed.

The molded article can take the form of a film, a sheet, a parison or pipe for forming a bottle or tube, a preform for forming a bottle or tube, and the like. Parison,
The formation of a bottle from a pipe or a preform is easily performed by pinching off the extrudate with a pair of split molds and blowing a fluid into the extrudate. Further, after cooling the pipe or the preform, the pipe or the preform is heated to a stretching temperature, stretched in an axial direction, and blow-stretched in a circumferential direction by a fluid pressure to obtain a stretch blow bottle or the like.

Further, the film or sheet is vacuum formed,
By applying means such as pressure forming, overhang forming, plug assist forming, etc., a cup-shaped or tray-shaped packaging container can be obtained. Furthermore, in the case of a multilayer film, it can be stacked or folded in a bag shape and the periphery thereof can be heat-sealed to form a bag-like container.

[Packaging Body] The packaging container of the present invention is useful as a sealed packaging container for heating the contents by hot water sterilization, hot filling, retort sterilization, and the like, and is sealed when a gas barrier resin is used. It is useful as a packaging container in which the contents are opened, microwave-heated in a microwave oven or the like, and cooked.
The contents to be filled are not particularly limited, but contents having a water content of 5% or more are particularly suitable from the viewpoint of oxygen absorption.

When a gas barrier resin is used as a barrier material without using a metal foil, it is the gas barrier resin layer that is useful for preventing oxygen permeation, that is, for blocking oxygen in a normal state. Under the condition where moisture and heat act simultaneously as described above, the oxygen scavenger present in the intermediate resin layer effectively serves to block oxygen, and the function is effectively shared depending on the state where the container is placed. . That is, under the condition where moisture and heat act simultaneously, the permeation of moisture occurs significantly through the moisture-resistant resin layer, and the gas barrier resin lowers the original oxygen barrier performance due to its moisture absorption and further rise in temperature. However, the moisture absorbed and the heat given activate the oxygen scavenger, and the oxygen scavenging by the oxygen scavenger is effectively performed, and as a result,
The transmission of oxygen during heat sterilization is also suppressed.

[0055]

The present invention will be further described with reference to the following examples.

Example 1 Iron powder and an additive were mixed in a V-type mixer, and the amount of the additive was 3.5.
A deoxygenating agent having a wt% was prepared. Next, using a pelletizer consisting of a twin-screw extruder / strand die / cooling unit / cutter, pellets were prepared by mixing 25 wt% of polypropylene with an MI of 1. The pellets were sliced using a hot press to obtain a sample for measuring oxygen absorption.
The oxygen absorption of the oxygen absorber and the resin containing the oxygen absorber is as follows: 1 ml of the sample and water are placed in an oxygen-impermeable aluminum foil laminate cup so that the two do not mix with each other, and the aluminum foil laminate lid is oxygen-impermeable in the atmosphere. And then stored at 50 ° C. for 1 day, and the oxygen concentration in the container was measured by gas chromatography and determined from the change in oxygen concentration (initial inner volume: 73 ml (STP), initial oxygen concentration: 20.9)
%). The pH of the additive used was measured using a pH meter (HM-30S, manufactured by Toa Denpa Kogyo KK) using a distilled water saturated solution of the additive.
Glass electrode used: 25 according to GST-5311C)
Measured in ° C. Table 1 shows the obtained results. The absorption amount is a value converted per 1 g of the oxygen scavenger.

Although no remarkable difference was observed in the oxygen absorption amount between the product of the present invention (FeCl ₃ , SnCl ₂ ) and the oxygen scavenger containing the comparative product as an additive, a remarkable difference was observed when blended into a resin. As shown in the figure, the product of the present invention in which the additive having a pH of the saturated solution of 1 or less was a deoxidizer was excellent.

[0058]

[Table 1] Oxygen absorption amount of oxygen absorber and resin product containing oxygen absorber Additive type Oxygen consumption / ml (STP) / oxygen absorber-g pH Oxygen absorber resin formulation Inventive product SnCl ₂ 0 255 149 FeCl ₃₀ 255 185 Comparison NaCl 6 253 73 Target product MgCl ₂ 6 260 47 CoCl ₂ 2 259 109

Example 2 A deoxidizer prepared in the same manner as in Example 1 was added to a linear low-density polyethylene (LLDPE) having an MI of 25% by weight.
They were blended to produce pellets. Next, a film comprising an oxygen scavenger-containing resin layer, a urethane-based adhesive layer, and an LLDPE layer was produced. The thickness of the film was a 50 micron oxygen-containing compound-containing resin layer, a 5 micron adhesive layer, and a 15 micron polyethylene layer. It was cut into a square of 30 mm square, and the oxygen absorption was measured at a storage temperature of 22 ° C. in the same manner as in Example 1. Table 2 shows the obtained results.

[0060]

Table 2 Oxygen consumption of film Oxygen consumption / ml (STP) / cm ² Additive 1 day 1 week 2 weeks Inventive product FeCl ₃ 0.09 0.26 0.30 SnCl ₂ 0.06 0.19 0.23 Comparative NaCl 0.01 0.03 0.04 Target product MgCl ₂ 0.04 0.14 0.16

Example 3 An oxygen scavenger was produced in the same manner as in Example 1, and then pellets were produced with the same composition as in Example 2. Using these pellets, a film comprising an LLDPE layer and a resin layer containing an oxygen scavenger was blown. Further, PET and aluminum foil were laminated using a urethane-based adhesive. The layer structure of the film was 12 micron PET, 7 micron aluminum foil, adhesive layer, 50 micron oxygen-containing resin layer, and 15 micron LLDPE layer. This laminate film is used as a cover material for an oxygen-impermeable cup (area: 3).
2 cm ² ), water was added to the container and the mixture was stored at 22 ° C., and the change in oxygen concentration in the container was measured (initial head space: 20 ml (STP), initial oxygen concentration: 20.
9%). The results obtained are shown in FIG.

[0062]

According to the present invention, among the water-soluble salts, a metal salt having a pH (25 ° C.) of 1.0 or less as a saturated aqueous solution is selected, and this is combined with iron powder. By being blended with a thermoplastic resin, blended with the resin, a markedly improved oxygen absorption rate is achieved even in the molded state, and the oxygen concentration in the container, of course, after a lapse of days, even in the initial stage It has become possible to provide a hermetically sealed packaging container that can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between oxygen concentration in a container and aging.

FIG. 2 is a sectional view showing an example of a multilayer structure of the container of the present invention.

FIG. 3 is a sectional view showing another example of the multilayer structure of the container of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Container wall 2 Outer layer of moisture resistant thermoplastic resin 3a, 3b Adhesive resin layer 4 First intermediate layer composed of gas barrier resin 5 Second intermediate layer composed of resin composition containing an oxygen scavenger 6 Moisture resistance Inner layer of plastic resin 7 Third intermediate layer composed of resin composition containing adsorbent deodorant

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08K 3/08 C08K 3/08 3/16 3/16 C08L 23/00 C08L 23/00 C09K 15/04 C09K 15/04 // A23L 3/00 101 A23L 3/00 101A

Claims (6)

[Claims] (A) a thermoplastic resin, and (B) (B-
1) pH as iron powder and (B-2) saturated aqueous solution
(25 ° C.) is an iron-based oxygen scavenger comprising a metal salt having a value of 1.0 or less, and 1 to 100 parts by weight of the iron-based oxygen scavenger (B) per 100 parts by weight of the thermoplastic resin (A) and iron The metal salt (B-2) is contained in an amount of 0.1 to 100 parts by weight of the powder (B-1).
An oxygen-absorbing resin composition which is present in an amount of 1 to 30 parts by weight. 2. The oxygen-absorbing resin composition according to claim 1, wherein the thermoplastic resin (A) is an olefin resin. 3. The oxygen-absorbing resin composition according to claim 1, wherein the metal salt is a halide of a metal of Group 3B, 4B or 8 of the periodic table. 4. The oxygen-absorbing resin composition according to claim 1, wherein the metal salt is iron chloride. 5. The method according to claim 1, wherein the metal salt is tin chloride.
The oxygen-absorbing resin composition according to any one of the above. 6. In a packaging container provided with a layer of an oxygen-absorbing resin composition, the oxygen-absorbing resin composition comprises (A) a thermoplastic resin, (B) (B-1) iron powder and (B- 2) An iron-based oxygen scavenger composed of a metal salt having a pH (25 ° C.) of 1.0 or less as a saturated aqueous solution, and an iron-based oxygen scavenger (B) per 100 parts by weight of the thermoplastic resin (A). ) Is 1
A resin composition containing the metal salt (B-2) in an amount of 0.1 to 30 parts by weight per 100 to 100 parts by weight of the iron powder (B-1) and 100 parts by weight of the iron powder (B-1).