JPH05247276A - Oxygen barrier resin composition - Google Patents

Abstract

(57) [Summary] [Purpose] An oxygen-barrier resin composition that gives excellent sanso-barrier properties and suppresses the odor associated with the oxidation of polyolefins without the use of other more expensive oxygen-barrier resins in combination. To provide. [Composition] An oxygen-barrier resin composition comprising a polyolefin, an oxidation catalyst, and an adsorbent.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an oxygen-barrier resin composition containing a polyolefin.

[0002]

BACKGROUND OF THE INVENTION Polyolefins are thermoplastic and therefore
Since it can be molded by various methods such as melt extrusion molding, injection molding, and hollow molding, and is inexpensive, it is widely used, for example, for packaging films, sheets, bottles, containers, and the like.

However, since such a polyolefin has a high oxygen permeability, another resin which has an oxygen barrier property and is more expensive, such as ethylene-vinyl acetate copolymer, is particularly used for packaging contents such as foods that are sensitive to oxygen. The present situation is that they are used in combination, laminated with polyvinylidene chloride, etc.

In order to improve this, it is conceivable to improve the oxygen barrier property of the polyolefin by adding an oxidation catalyst to the polyolefin containing a radical inhibitor of 500 ppm or less. Although excellent, there is a problem that odor is gradually generated after the processing due to the oxidation of the polyolefin.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and its object is to provide an excellent oxygen barrier property without using a more expensive other oxygen barrier resin in combination. Another object of the present invention is to provide an oxygen barrier resin composition that suppresses the odor associated with the oxidation of polyolefin.

[0006]

In order to solve such problems, the present invention provides an oxygen barrier resin composition containing a polyolefin, an oxidation catalyst and an adsorbent.

The present invention will be described in detail below. Examples of the polyolefin used in the present invention include low density polyethylene, medium density polyethylene, polyethylene such as high density polyethylene, polypropylene, polybutene, polypentene, copolymers of ethylene and propylene, copolymers of ethylene and butene, ethylene. And a pentene copolymer, and a homopolymer or a copolymer of a propylene monomer is preferably used from the viewpoint of oxygen barrier properties.

As the oxidation catalyst used in the present invention, a metal catalyst composed of a transition metal compound or the like is preferably used.

As such a transition metal, metals such as Co, Mn, Fe, Cu, Ni, Ti, V and Cr are preferably used, and Co is preferably used. As the compounds of these metals, salts of organic acids are preferably used. Examples of such organic acids include stearic acid, acetylacetonic acid, dimethyldithiocarbamic acid, linoleic acid, and naphthenic acid.

Further, as the oxidation catalyst used in the present invention, Al, Mg, Ca and Zn compounds are appropriately used because they are hygienic, colorless and inexpensive.

Further, porphyrin, phthalocyanine,
Organometallic complexes with quinoline as a ligand, iron chloride,
Inorganic salts such as cobalt blue can also be used.

The above-mentioned oxidation catalyst is used alone or as a mixture of two or more kinds. The higher the concentration of such an oxidation catalyst, the more excellent the effect of oxygen barrier property is. However, if the content is too large, slippage of the resin during molding becomes large and molding becomes difficult. Therefore,
The concentration of metal atoms in the oxygen barrier resin composition is 100.
It is preferable to contain it in an amount of from ppm to 2000 ppm.

Examples of the adsorbent used in the present invention include natural zeolite, synthetic zeolite, silica gel, activated carbon, activated clay, activated aluminum oxide, magnesium silicate, and aluminum silicate. Further, a synthetic hydrotalcite compound can also be used.

From the viewpoint of dispersibility of the adsorbent in the resin, the particle size of the adsorbent is preferably 100 μm or less, and particularly preferably 50 μm or less. Further, if the adsorbent is added at a high concentration, molding becomes difficult, so the amount added is preferably 10% by weight or less based on the resin.

When the radical inhibitor is contained in the polyolefin, its amount is preferably 500 ppm or less.

The oxygen barrier resin composition of the present invention and the method for producing the sheet and the container related thereto will be described in detail below.

The oxygen oxidation reaction of the resin according to the present invention is carried out by ultraviolet irradiation during processing or after processing of a film, sheet or container.
It can be accelerated by irradiation with light including infrared rays and far infrared rays, electron beam irradiation, irradiation with radiation such as α rays, β rays, γ rays, corona discharge, or external action such as heating.

Further, the oxygen barrier resin composition of the present invention may contain other thermoplastic resin.

The oxygen barrier resin composition of the present invention can be molded into a sheet, a container or other packaging material by using various molding methods using heat. For example, a film, a sheet, a pipe or the like can be formed by melt extrusion molding into a container shape by injection molding, or a hollow container such as a bottle shape by hollow molding. Hollow molding includes extrusion hollow molding in which a parison is molded by extrusion and then blown to perform molding, and injection hollow molding in which a preform is molded by injection molding and then blown to perform molding. Further, a method in which a metal catalyst is mixed with polyolefin, and the composition is left to oxidize the polyolefin and then mixed with the polyolefin and then extrusion-molded to produce a sheet is also preferably performed.

A method in which a masterbatch of the adsorbent is preliminarily molded and then added to the resin is also preferably carried out in order to further improve the dispersibility.

The molding temperature can be 200 to 320 ° C., which is a temperature generally used for thermoforming of polyolefins, but in the present invention, heating up to about 350 ° C. is possible.

In the present invention, the sheet, packaging material, container, etc. obtained by the above-mentioned molding may be a single layer, but may be used as a laminate with various layers. That is, for example, the polyolefin layer containing an oxidation catalyst absorbs oxygen over time and decomposes, so that the strength deteriorates, or deterioration such as whitening occurs due to generation of microcrystals, so that the strength of the entire container is maintained. Therefore, it is laminated with a shape-retaining resin layer made of a material that does not deteriorate in strength over time.

As such a laminate, preferably,
The one in which another thermoplastic resin layer, for example, a thermoplastic resin layer not containing an oxidation catalyst is formed on one side or both sides of the polyolefin layer containing the oxidation catalyst is used.

Other thermoplastic resin layers used include:
Polyester, polyolefin, polyamide, polyvinyl chloride, polyvinylidene chloride, polyacrylonitrile,
Examples thereof include layers such as polycarbonate and modified resins thereof.

As a method for laminating these layers, lamination using an adhesive, coextrusion molding, coinjection molding,
Each method such as co-extrusion blow molding or co-injection blow molding is used.

The oxygen barrier resin composition of the present invention can be used for various purposes. For example, it can be used as a material for a long-term storage container such as a food, that is, a substance that is easily modified by oxygen. When it is formed into a sheet or film, it can be used as a bag material, a blister pack material, a container lid, and the like. When molded into a pipe shape, the container can be made by sealing the openings at both ends with a metal lid or the like. Further, in the case of an injection molded container or bottle, it can be used as it is as a container.

[0027]

As described above, the oxidation catalyst used in the present invention promotes the oxygen oxidation of the polyolefin, thereby reacting the oxygen that permeates and permeates the polyolefin with the polyolefin to reduce the oxygen permeability, As a result, the oxygen barrier property of the polyolefin can be improved.

A metal catalyst composed of a transition metal compound or the like is preferably used as such an oxidation catalyst in the process of transition of a metal ion from an oxidized state to a reduced state or from a reduced state to an oxidized state in the case of a transition metal. It is considered that oxygen reacts with polyolefin to act as an oxidation catalyst.

In the oxygen barrier resin composition of the present invention, the polyolefin easily forms radicals by light or heat during processing or storage in the presence of an oxidation catalyst,
Polymer radicals are generated. This reacts with oxygen in the air to form peroxy radicals. Furthermore, this peroxy radical abstracts the hydrogen of the polyolefin,
It forms polymer radicals with hydroperoxide. It is considered that this hydroperoxide is decomposed into an alkoxy radical and a hydroxy radical and further reacts with the polyolefin to generate a radical.

The adsorbent used in the present invention adsorbs and removes odorous components on the surface of the porous substance.

[0031]

【Example】

<Example 1> Polypropylene (“Hipol B240” manufactured by Mitsui Petrochemical Co., Ltd. (melt index 0.5, no radical inhibitor)) was used as a polyolefin, and a natural zeolite (Japan Activated Shirado Co., Ltd.) was used as an adsorbent.
2% by weight based on the polypropylene, and cobalt stearate as an oxidation catalyst in an amount of 200 ppm at a cobalt atom concentration, to obtain a single layer sheet (8).
00 μm) was extruded at an extrusion temperature of 200 ° C. to prepare a sheet sample 1.

Comparative Example 1 A comparative sheet sample 1 was prepared in the same manner as in the preparation of the sheet sample 1 except that the natural zeolite was not included.

Comparative Example 2 Further, as another thermoplastic resin layer, a single-layer sheet (800 μm) of polypropylene (“Hipol B240” (melt index 0.5, no radical inhibitor) manufactured by Mitsui Petrochemical Co., Ltd.) Extrusion temperature 2
Comparative sheet sample 2 was prepared by extrusion molding at 00 ° C.

Obtained sheet sample 1, comparative sheet sample 1
After extrusion molding, each of Nos. 2 to 2 was left at 25 ° C., and the oxygen permeability was measured with time immediately after molding. The measurement is "Ox
-TRAN10 / 50A "(manufactured by Modern Control Co., USA) at 25 ° C. The results are shown in Table 1.

[0035]

[Table 1]

The sheet sample 1 and the comparative sheet sample 1 have an oxygen barrier property.

Sheet sample 1 and comparative sheet sample 1
Immediately after molding, the sample of No. 3 was cut into a circle of 30 cm ² and stored at 25 ° C. as with the sample for measuring oxygen permeability, and was subjected to gas chromatography over time (“GC-14 manufactured by Shimadzu Corporation”).
A ”) was used to measure the odor. However, in order to agglomerate the odor, the sample was sandwiched in the mouth of a 480 ml vial from 24 hours before the measurement, the container was tightly stoppered, aged at 55 ° C., and the odor emitted from one side of the sample was measured by the headspace method.

Table 2 shows the gas odor component removal rate of the sheet sample 1. As for the gas odor component removal rate, assuming that the total amount of the gas odor component detected in the sheet sample 1 is X and the total amount of the gas odor component of the comparative sheet sample 1 is Y, the gas odor component removal rate =
It is calculated by (Y−X) / Y × 100.

[0039]

[Table 2]

As is clear from Table 2, sheet sample 1
Is an oxygen-barrier composite resin composition that has less odor than Comparative Sheet Sample 1, has oxygen barrier properties, and has suppressed odor.

<Example 2> Polypropylene as a polyolefin ("Hipol B24" manufactured by Mitsui Petrochemical Co., Ltd.)
0 ”(melt index 0.5, no radical inhibitor)), and silica gel (Kanto Chemical Co., Inc.) powder as an adsorbent was added to the polypropylene 2
% By weight, cobalt stearate as an oxidation catalyst was added in an amount of 200 ppm at a cobalt atom concentration, and a single layer sheet (800 μm) was extrusion-molded at an extrusion temperature of 200 ° C. to prepare a sheet sample 2.

Comparative Example 3 A comparative sheet sample 3 was prepared in the same manner as in the preparation of the sheet sample 2 except that the silica gel was not included.

Further, as another thermoplastic resin layer, polypropylene (manufactured by Mitsui Petrochemical Co., Ltd., "Hipol B24") is used.
0 "(melt index 0.5, no radical inhibitor) single layer sheet (800 μm) extrusion temperature 200 ° C
Comparative sheet sample 4 was prepared by extrusion molding.

The oxygen permeability of the obtained sheet sample 2 was evaluated in the same manner as in Example 1 and the results are shown in Table 3.

[0045]

[Table 3]

As is clear from Table 3, oxygen barrier properties are obtained in the sheet sample 2 and the comparative sheet sample 1.

Table 4 shows the results of evaluating the odor removal rate of the sheet sample 2 with respect to the comparative sheet sample 1 in the same manner as in Example 1.

[0048]

[Table 4]

As is clear from Table 4, sheet sample 2
Is an oxygen-barrier resin composition having less odor than Comparative Sheet Sample 1 and having oxygen barrier properties and suppressing odor.

[0050]

As described in detail above, the oxygen-barrier resin composition of the present invention is excellent in moldability because it uses a polyolefin, and has an oxidation catalyst, so that other expensive oxygen can be used. It has an excellent oxygen barrier property without being laminated with the barrier resin composition, and has an adsorbent to suppress the odor associated with oxidation. Therefore, it has become possible to manufacture sheets and containers having these excellent properties.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Umeyama 1-5-1 Taito, Taito-ku, Tokyo Toppan Printing Co., Ltd. (72) Naoki Masuda 1-5-1 Taito, Taito-ku, Tokyo Toppan Imprint Co., Ltd.

Claims (1)

[Claims] 1. An oxygen barrier resin composition comprising a polyolefin, an oxidation catalyst and an adsorbent.