JPH0597162A - Lid material - Google Patents

Abstract

PURPOSE:To provide lid material which absorbs the oxygen present in food or drink and prevents oxidization of contents such as food and drink leading to loss of its flavor or the degradation by sealing with the lid a container filled with the food or drink. CONSTITUTION:A lid material 1 comprises partly or wholly an oxygen absorbing material 3 wherein the polyolefin having tertiary hydrogen is mixed with a transition metal compound in such an amount that 0.001-20wt.% of the transition metal is contained based on the weight of the polymer.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an oxygen-absorbing lid material. More specifically, the present invention relates to a lid material which constitutes the whole or a part of the structure of an oxygen absorbent obtained by adding a transition metal compound to a polyolefin having tertiary hydrogen.

[0002]

2. Description of the Related Art Conventionally, it has been known that foods, beverages, etc. enclosed by covering a container with a lid are oxidized and discolored by oxygen permeating from the outside to the inside of the container. In order to prevent oxidative deterioration of foods and beverages, a method of using a high barrier material that is difficult for oxygen to permeate in the container and the lid material is widely used, but compared to a metal or glass container or lid, a high barrier material is used. Plastic containers and lids cannot completely prevent the permeation of oxygen, and foods and beverages with a moderate content are gradually oxidized and transformed. Also, from the beginning, the oxidative discoloration of foods and beverages is actually caused by oxygen contained in foods and beverages and oxygen contained in the head space of the container.

[0003]

DISCLOSURE OF THE INVENTION The present invention is intended to solve the above-mentioned conventional problems, and an object of the present invention is to put foods and beverages in an oxygen-absorbing container and to cover the oxygen-absorbing lid. Alternatively, by using a lid that does not allow oxygen to permeate easily, the oxygen present in foods and beverages with contents can be absorbed by the container and lid to prevent the oxidative deterioration of foods and beverages and to improve the quality of foods and beverages. It is intended to provide a lid material that can be maintained for a period of time.

[0004]

That is, according to the present invention, a transition metal compound is blended with a polyolefin or a copolymer thereof having a tertiary hydrogen in the molecule in an amount of 0.001 to 20% by weight as a transition metal with respect to the polymer. Oxygen-absorbing material is an oxygen-absorbing lid material constituting the whole or part of the structure of the lid material, the lid material, by mounting in a container containing food, beverages, pharmaceuticals, precision electronic components, It is characterized by maintaining the quality of the contents by making the oxygen concentration inside the container substantially zero.

In the present invention, the polyolefin having a tertiary hydrogen in the molecule or a copolymer thereof is atactic polypropylene, isotactic polypropylene, syndiotactic polypropylene, ethylene propylene copolymer, propylene butene copolymer, propylene. Styrene copolymer, polyisobutene, ethylene isobutene copolymer, poly-4-methylpentene-1, methylpentene ethylene copolymer, propylene methylpentene copolymer, low density polyethylene, polystyrene and the like,
Blends of these tertiary hydrogen-containing polyolefins, these tertiary hydrogen-containing polyolefins and other polymers, that is, tertiary hydrogen-free polyolefins, polyesters, polyamides, polyvinyl chloride, polyvinylidene chloride, chloride Blends with vinylidene-ethyl acrylate copolymer, ethylene vinyl alcohol copolymer, polyacrylonitrile, bisphenol A-based polycarbonate, polysiloxane, cellulose derivative, ionomer, polyurethane and the like are also included.

Here, the polyester means a polycondensate of dicarboxylic acid and glycol, and may be a homopolyester or a copolyester. Examples of polyamides include nylon 6, nylon 66, nylon 6,1
2, metaxylylenediamine / adipic acid type polyamide (MXD-6) and the like.

Preferred metals of the transition metal compound used in the present invention are transition metals having atomic numbers 23 to 29 and rhodium, and at least one kind of compounds of these metals. Examples of these transition metal compounds include organic acid salts of these transition metal ions, acetylacetonate complexes, phthalocyanine complexes, monoalkyl phosphate ester salts, dialkyl phosphate ester salts, aryl phosphate ester salts, and the like. As the compound, those having good compatibility with the above-mentioned oxidizable polymer are particularly desirable. Specifically, in the case of polypropylene, salts of organic acids having a long-chain alkyl group such as stearic acid, palmitic acid, lauric acid, decanoic acid, and octanoic acid, acetylacetonate complex, dihexadecylphosphoric acid. Ester salt, didecyl phosphate ester salt, dibutyl phosphate ester salt, monododecyl phosphate ester acid, 1
-Naphthyl phosphate ester salts and the like. Of course,
The compounds of the transition metals having atomic numbers 23 to 29 and rhodium used in the present invention are not limited to those described above. These transition metal compounds are added to the oxidizable polymer alone or as a mixture, and the addition amount thereof is 0.001 to 20% by weight based on the oxidizable polymer as a metal, It is preferably 0.005% by weight to 10% by weight. If the amount added is less than this, effective oxygen absorption performance cannot be obtained,
If it exceeds this range, improvement of oxygen absorption performance cannot be obtained, and a problem in molding occurs.

Inorganic additives such as activated carbon, titanium oxide, pigments, calcium carbonate and silicon oxide can be blended in the oxygen absorbent of the present invention. It is particularly effective to add a deodorizing agent such as activated carbon or zeolite.

In the present invention, the oxygen absorbing material constitutes the entire structure of the lid material. The lid material means a polyolefin having tertiary hydrogen in the molecule or its copolymer and a transition metal having atomic numbers 23 to 29 and rhodium. A cap, a screw cap, a heat-sealing film, which is composed only of an oxygen absorber added with at least one transition metal compound, or a blend of the oxygen absorber and another polymer of the oxygen absorber. Refers to a sheet-like lid.

The lid material in which the oxygen absorbing material of the present invention constitutes a part of the structure of the lid material means the oxygen absorbing material of the present invention alone or a blend of the oxygen absorbing material and another polymer of the oxygen absorbing material. It refers to the case where an object forms a part of a stopper, a cap, a screw cap, a heat-sealing film or a sheet-like lid.

An example of the lid is shown by a cap. (A) A cap (FIG. 1) in which the oxygen absorbing material constitutes the entire structure of the lid material, and (b) One of the structures of the oxygen absorbing material in the lid material. Examples include a cap (FIG. 2) that constitutes a part, (c) a cap (FIG. 3) in which the intermediate layer is the oxygen absorbent, and the like.

The oxygen-absorbing polypropylene film, which is the oxygen-absorbing material of the present invention, does not change its oxygen-absorbing ability even in the unstretched, uniaxially stretched, or biaxially stretched state. Can be used as

[0013]

EXAMPLES The present invention will now be described with reference to examples. Example 1 Melt index 2.5 g / 10 min (230 ° C.)
Cobalt stearate in 100 parts of polypropylene 5.
Three parts (5,000 ppm as cobalt) were mixed, and a screw cap having an inner diameter of 32 mm and a height of 20 mm was molded by an injection molding machine. PE with a capacity of 1 liter
Pure water was put into the T bottle up to 50 mm from the opening, the screw cap was closed, and the bottle was left at a temperature of 20 ° C. The oxygen concentration in the head space of the PET bottle was 21% immediately after the cap was closed, but decreased to 1.5% after being left for 6 days. The oxygen concentration in the headspace after closing with an aluminum screw cap for comparison was 21% after 6 days.

Example 2 100 parts of the above polypropylene was mixed with 5.3 parts of cobalt stearate (5,000 ppm as cobalt), and a maleic anhydride modified polypropylene (Admer; manufactured by Mitsui Petrochemical Co., Ltd.) was used by a coextrusion injection molding machine. As an adhesive layer,
Co-injection molding with 6-nylon was carried out to form a screw cap having 6-nylon as an outer layer and polypropylene + cobalt stearate as an inner layer and having an inner diameter of 32 mm and a height of 20 mm. Pure water was put into a PET bottle having an inner volume of 1 l up to 50 mm from the opening, and the bottle was closed with a screw cap and left at 20 ° C. The oxygen concentration in the headspace was 21% immediately after the plug was closed, but it was 1.0 after 6 days.
Fell to%.

Example 3 Example 2 was repeated except that 4.9 parts of copper stearate was used instead of cobalt stearate and a copolyester (Vylon made by Toyobo) was used for the adhesive layer. Similarly, when a screw cap was molded and evaluated, the oxygen concentration in the headspace was 2. after 6 days.
It fell to 0%.

Example 4 To 100 parts of the polypropylene described above, 5.3 parts of cobalt stearate (5,000 ppm as cobalt) were mixed and extruded into a sheet having a thickness of 250 μm. This sheet is cut into a diameter of 32 mm, and the inner diameter is 32 mm and the height is 20 mm.
It is used for the liner of the aluminum screw cap of, and pure water is put into the glass bottle with an internal capacity of 500 ml from the opening.
It was put up to the position of mm, closed with this screw cap, and left at a temperature of 20 ° C. The oxygen concentration in the headspace was 21% immediately after capping, but in 12 days,
It fell to 1.5%. For comparison, the capped aluminum screw cap with a normal liner is 1
The oxygen concentration in the headspace was 21% even after 2 days.

Example 5 The oxygen absorbing sheet having a thickness of 250 μm obtained in Example 4 was laminated with an aluminum foil having a thickness of 35 μm by using an adhesive. Next, an acrylic resin adhesive was applied to the surface of the oxygen-absorbing sheet, heat-sealed in the opening of a glass container having a diameter of 70 mm and a height of 100 mm, and left at 20 ° C. The oxygen concentration in the container having the seal diameter was 21%, but it decreased to 1.0% after 6 days. For comparison, an aluminum foil was coated with an acrylic adhesive and heat-sealed in a glass container, but the oxygen concentration in the container was 21% after 12 days.

[0018]

EFFECT OF THE INVENTION The lid material using the oxygen absorbing material prepared by blending a transition metal with a polyolefin having tertiary hydrogen such as polypropylene of the present invention as a whole or a part of the structure of the lid material is used as a lid material. By sealing, it is possible to prevent oxidative deterioration and deterioration of the contents such as foods and drinks.

[Brief description of drawings]

FIG. 1 is a schematic view showing a cross section of a cap of the present invention molded with an oxygen absorbent.

FIG. 2 is a schematic view showing a cross section of the cap of the present invention in which the oxygen absorbent constitutes a part of the structure of the cap.

FIG. 3 is a schematic view showing a cross section of a cap of the present invention in which an oxygen absorbing material is laminated as an intermediate layer.

[Explanation of symbols]

 1 Cap 2 Base material 3 Oxygen absorber

Claims (1)

[Claims] 1. The whole structure of a lid material of an oxygen absorbing material in which 0.001 to 20% by weight of a transition metal compound is blended into a polyolefin or a copolymer thereof having a tertiary hydrogen in the molecule as a transition metal. Or an oxygen-absorbing lid material that forms a part.