JPH06100042A - Oxygen barrier laminate - Google Patents

Abstract

PURPOSE:To improve the workability and oxygen barrier property by laminating a thermoplastic resin layer containing a metallic oxide and a thermoplastic resin layer containing an absorbent, for the title laminate for packaging material. CONSTITUTION:The title oxygen barrier laminated body is constituted by laminating a thermoplastic resin layer for which, a metallic oxide consisting of an organic acid chloride of a stearaic acid, etc., and a metal ion such as Co, etc., is added to, e.g. high density polyethylene, etc., on a thermoplastic resin layer for which an absorbent with physical absorbing capability such as natural zeolite, etc., is added to the same thermoplastic resin. The metallic oxide may be contained approximately 10-1000ppm by the atomic concentration. Also, the particle diameter of the absorbent is preferably approx. 100mum or less, and the adding quantity shall be approx. 10wt.% or less. Also, the thickness of the metallic oxide-containing layer shall be approx. 10-100mum, and the thickness of the absorbent-containing layer shall be one fifth or more of the thickness of the metallic oxide-containing layer. Then, a packaging is done with the metallic oxide-containing layer to be outside.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an oxygen barrier laminate provided as a packaging material.

[0002]

2. Description of the Related Art Currently, packaging materials are mainly polymer materials that can be easily processed into various shapes such as films, sheets, bottles and containers, and are lightweight and inexpensive to transport. What has been used is being used.

A high oxygen barrier property is required especially when the contents to be packaged are those that are easily deteriorated and deteriorated by oxidation such as foods. In order to meet such demands, conventional materials such as saponified ethylene-vinyl acetate copolymer (hereinafter referred to as EVOH) and polyvinylidene chloride are used as polymer materials or films on which aluminum or silicon oxide is vapor-deposited. Was offered to.

However, since the above-mentioned polymer material having an oxygen barrier property is expensive, its practical use is limited in terms of cost. Further, EVOH has a drawback that the oxygen barrier property is deteriorated by moisture absorption.

On the other hand, there is a drawback that the workability is poor because a vacuum device is used for vapor deposition of aluminum or silicon oxide. Further, these vapor-deposited thin films have a drawback that the oxygen barrier property becomes unstable due to generation of pinholes and cracks.

The present inventors have already improved the oxygen barrier property of a thermoplastic resin by providing a composition comprising a thermoplastic resin containing a radical inhibitor of 500 ppm or less and a metal compound, and have an excellent gas barrier property. It was found that a sexual composition could be obtained, and a patent application was filed. (Japanese Patent Application No. 3-5
(0581)

However, although these compositions have excellent oxygen barrier properties, there is a problem that after processing, odor is gradually generated due to the oxidation of the thermoplastic resin.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention that the cost is low, the processability is high, the oxygen barrier property is high, and the odor is suppressed. It is to provide a laminated body.

[0009]

In order to solve this problem, the present invention is characterized in that a thermoplastic resin layer containing at least a metal compound and a thermoplastic resin layer containing an adsorbent are laminated. A barrier laminate is provided.

The present invention will be described in detail below. When the oxygen barrier laminate of the present invention is used as a package, a thermoplastic resin layer containing an adsorbent is located on the inner surface side and a thermoplastic resin layer containing a metal compound is located on the outer surface side.

The thermoplastic resin for the thermoplastic resin layer in the present invention is preferably a polyolefin, for example, high density polyethylene, medium density polyethylene, low density polyethylene, linear low density polyethylene, polypropylene, polybutene, polymethylpentene, etc. And a copolymer of two or more monomers selected from olefins such as ethylene, propylene, butene, and methylpentene. Further, as the other thermoplastic resin, polyvinyl chloride, nylon, EVOH, polyester or the like can be used.

As the metal compound added to the thermoplastic resin, stearic acid, naphthenic acid, linoleic acid, dimethyldithiocarbamic acid, etc., and Co, Ni, Fe, A
Organic acid salts with metal ions such as 1, Mg, Mn, Cu, V and Cr are used, and in particular, organic metal complex salts having porphyrin, phthalocyanine, quinoline and the like as ligands are also preferably used. Inorganic salts such as iron chloride, aluminum chloride and cobalt blue can also be used. Further, these metal compounds can be used alone or as a mixture of two or more kinds.

These metal compounds may be contained in the thermoplastic resin in an atomic concentration of metal of 10 to 1000 ppm, and more preferably 50 to 500 ppm.

The thermoplastic resins of the present invention, especially polyolefins, are generally susceptible to oxidation and are commonly used with radical inhibitors. However, it is sufficient if the radical inhibitor is not added to the thermoplastic resin containing the metal compound in the present invention, or if it is 500 ppm or less. If the amount added is in this range, the radical inhibitor cannot prevent the progress of oxidation of the polyolefin at all and takes in oxygen, so it does not hinder the present invention. On the contrary, the ability of the oxygen barrier property can be controlled by adjusting the addition amount of the radical inhibitor.

The adsorbent used in the present invention mainly has a physical adsorption ability and adsorbs an odorous component on the surface of a porous substance to remove it. Such adsorbents include natural zeolite, synthetic zeolite, silica gel, activated carbon,
Examples include activated clay, activated aluminum oxide, and magnesium silicate. Further, a synthetic hydrotalcite-based adsorbent 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. Therefore, it is desirable that the addition amount be 10% by weight or less based on the resin. Further, a method in which a masterbatch of the adsorbent is preliminarily molded and then added to the resin is also preferably performed in order to further improve the dispersibility of the adsorbent.

The oxygen barrier laminate according to the present invention can be formed into a film, a sheet, a container, other packaging materials and the like by using various forming methods by heat. The thermoplastic resin layer containing the metal compound and the thermoplastic resin layer containing the adsorbent are preferably formed by coextrusion molding, but they may be adhered by an adhesive.

The thickness of the thermoplastic resin layer containing the metal compound according to the present invention may be adjusted according to the content of the metal compound, and is not particularly limited, but is 10 to 10
A thickness of 00 μm is preferable. The thickness of the layer containing the adsorbent is preferably ⅕ or more of the thickness of the thermoplastic resin layer containing the metal compound.

In the present invention, the laminate obtained by the molding may have two layers, but it can be used as a laminate with various layers. For example, it is also preferable to laminate a thermoplastic resin layer containing an adsorbent or a thermoplastic resin layer containing nothing on the outside of the thermoplastic resin layer containing a metal compound of the laminate. It is also preferable to laminate a thermoplastic resin layer containing nothing inside the thermoplastic resin layer containing the adsorbent of the laminate to further reduce the influence on the contents.

In the case of a package, it is also preferable to sequentially laminate the oxygen barrier material layer and the base material in this order on the outside of the thermoplastic resin layer containing the metal compound of the laminate with an adhesive. .

The laminate can be manufactured by a known processing method. For example, by a melt extrusion molding method, a thermoplastic resin containing an adsorbent and a thermoplastic resin containing a metal compound are processed as a laminated film, while a polyvinylidene chloride-coated film is bonded by an adhesive. Can be configured.

As the base material for the package, various films such as polypropylene, polyester and nylon can be used.

Polyvinylidene chloride or EVOH can be used as the oxygen barrier material for the oxygen barrier material layer in the package. The former may be coated on a substrate, for example. Further, as another material, a material such as aluminum or silicon oxide deposited on a film-shaped substrate can be used.

An adhesive is used for adhering the laminated film of the thermoplastic resin containing the oxygen barrier material and the adsorbent and the thermoplastic resin containing the metal compound. As the adhesive, two kinds of films can be bonded together with sufficient strength, and examples thereof include a urethane dry laminate adhesive.

[0025]

In the thermoplastic resin layer containing the metal compound, the function of physically suppressing the permeation of oxygen due to so-called dissolution and diffusion, and the fact that the thermoplastic resin is oxidized by the catalytic action of the metal compound, oxygen is contained in the layer. Oxygen barrier property is expressed by the function of trapping. Especially the latter works
It shows the action of trapping oxygen remaining in the sealed package when dissolved in the wall.

As the thermoplastic resin according to the present invention, polyolefin easily forms radicals due to light or heat during processing or storage in the presence of an oxidation catalyst, whereby polymer radicals are generated. This reacts with oxygen dissolved in the resin to form peroxy radicals. Further, this peroxy radical abstracts hydrogen from the polyolefin to form a polymer radical 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 thermoplastic resin layer containing an adsorbent according to the present invention absorbs and reduces the odor associated with the oxidation of the thermoplastic resin layer containing a metal compound. Also,
A metal compound in a thermoplastic resin containing a metal compound,
It has a function of preventing elution of the oxide of the above-mentioned thermoplastic resin into the contents during use, and improving the heat-sealing strength when it is processed as a package.

[0028]

EXAMPLES The present invention will be specifically described below based on examples, but the present invention is not limited to the following examples.

Example 1 A thermoplastic resin containing a metal compound-containing thermoplastic resin layer containing cobalt (II) stearate at a concentration of 200 ppm of cobalt (II) stearate and no radical inhibitor-containing propylene, and an adsorbent. The polypropylene containing 2% by weight of silica gel as a layer was coextruded at 210 ° C. to obtain a sheet sample 1 having a layer thickness of 500 μm and 300 μm, respectively.

A comparative sheet sample 1 was prepared in the same manner as in the preparation of the sheet sample 1 except that the silica gel was not included. In addition, a comparative sheet sample 2 was prepared in the same manner as in the preparation of the sheet sample 1, except that the silica gel and the cobalt stearate were not included.

Each of the obtained sheet sample 1 and comparative sheet samples 1 and 2 was extrusion-molded and left at 25 ° C., and the oxygen permeability was measured with time immediately after the molding. Measurement is Ox
-TRAN100 (made by Modern Control) 25 ℃
I went there. The results are shown in Table 1. A high oxygen barrier property was confirmed in Sample 1 and Comparative Sample 1.

[0032]

[Table 1]

Immediately after molding, the samples of Sample 1 and Comparative Sample 1 were cut into a circle of 30 cm ² and stored at 25 ° C. similarly to the sample for measuring oxygen permeability, and a gas chromatograph (manufactured by Shimadzu Corporation: “GC- 14A ") was used to measure the odor.

However, in order to aggregate the odor, the
From 4 hours before, the sample was sandwiched in the mouth of a 480 ml vial bottle and tightly stoppered, aged at 55 ° C., and the odor emitted from the adsorbent-added layer side was measured.

Table 2 shows the gas odor component removal rate of Sample 1. As for the gas odor component removal rate, the total amount of gas odor components detected in Sample 1 is X, and the total amount of gas odor components in Comparative Sample 1 is Y, and the gas odor component removal rate = (Y−X) / Y × 1
It is calculated by 00.

[0036]

[Table 2]

As is apparent from Table 2, Sample 1 is a laminate having less odor than Comparative Sample 1, having an oxygen barrier property and suppressing odor.

<Example 2> From the outside, polypropylene containing no radical inhibitor to which nothing was added, and cobalt (II) stearate as a thermoplastic resin layer containing a metal compound were added in an amount of 200 ppm at a cobalt atom concentration. Polypropylene and the polypropylene containing 2% by weight of silica gel as a thermoplastic resin layer containing an adsorbent were co-extruded at an extrusion temperature of 210 ° C. to form layer thicknesses of 10 μm, 25 μm, and 10 μm, respectively. A laminated film of was prepared.

A K-coated surface of a non-stretched polypropylene film having a thickness of 25 μm and a stretched polyethylene terephthalate film having a thickness of 12 μm as a base material coated with K as an oxygen barrier material layer was dry laminated with a urethane adhesive.

A film sample 2 having a total thickness of 82 μm was obtained by thermally laminating the dry laminated film and the laminated film.
Got

A film sample 3 was obtained in the same manner as the film sample 2 except that the silica gel was changed to activated carbon. A comparative film sample 3 was obtained in the same manner except that the silica gel was not included in the preparation of the film sample 1. Comparative film sample 4 was obtained in the same manner except that the silica gel and the cobalt stearate were not included in the preparation of the film sample 1.

Table 3 shows the results of evaluating the oxygen transmission rates of the obtained film samples 2 and 3 and comparative film samples 3 and 4 in the same manner as in Example 1. In Samples 2 and 3 and Comparative Sample 3,
A high oxygen barrier property was confirmed.

[0043]

[Table 3]

The prepared samples 2 and 3 and comparative samples 3 and 4 were
The stretched polyethylene terephthalate film was placed on the outer surface, and heat sealed to form a four-way pouch. This pouch is filled with 400 cc of air, and the temperature is 25 ° C.
Was stored in and the oxygen concentration was measured over time. The results are shown in Table 4.

[0045]

[Table 4]

In Samples 2 and 3 and Comparative Sample 1, it was confirmed that the residual oxygen concentration in the pouch was lowered.

The sample pouch was stored at 25 ° C., and the gas in the pouch was measured for odor with time using a gas chromatograph (“GC-14A” manufactured by Shimadzu Corporation).

The odor removal rate of Samples 1 and 2 relative to Comparative Sample 1 was determined in the same manner as in Example 1, and the results are shown in Table 5.

[0049]

[Table 5]

As is clear from Table 5, Samples 2 and 3
Is a laminate having less odor than Comparative Sample 3, having oxygen barrier properties, and suppressing odor.

[0051]

As described in detail above, according to the present invention, it is possible to provide a laminate having a low odor and a high oxygen barrier property by using an inexpensive thermoplastic resin. As a result, the food inside the package does not deteriorate and deteriorate,
It has become possible to store it for a long time.

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

Claims (1)

[Claims] 1. An oxygen barrier laminate comprising a thermoplastic resin layer containing at least a metal compound and a thermoplastic resin layer containing an adsorbent.