JPS6132348B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an oxygen-absorbing resin composition comprising a thermoplastic resin uniformly mixed and filled with iron powder and inorganic electrolyte powder. In general, some foods and drugs deteriorate significantly when they come into contact with oxygen in the air, and when preserving them, methods are used to protect them by coexisting with oxygen scavengers to prevent harm from oxygen. It's here. As oxygen scavengers, reducing organic compounds such as dithionites and sulfoxylates, or powders or granules of transition metals such as iron have generally been used. In actual use, in order to prevent these substances from coming into direct contact with the food or medicine concerned, they should be wrapped in a breathable film, or adsorbed onto a pulp sheet, then shaped into a sheet and placed in an airtight container. They were allowed to coexist. This lowered the oxygen partial pressure within the container. However, with this method, it is necessary to prepare or replace the oxygen scavenger each time, which inevitably causes inconvenience in handling. This inconvenience would be eliminated if the container itself was equipped with a function equivalent to the effect of deoxidizing. In response to this demand, the inventors of the present invention conducted various studies and focused on a method of mixing a reducing inorganic substance with a resin. The gist of the present invention is to use a mixture of iron powder and inorganic electrolyte powder as an oxygen scavenger, and to uniformly mix and fill the thermoplastic resin with the mixture. Iron powder was selected as the oxygen scavenger considering its functionality and economy. The iron powder does not need to be of particularly high purity, as long as it has considerable activity toward oxygen. Iron powder captures oxygen in the atmosphere and becomes oxidized. At this time, the presence of some moisture is essential to promote oxidation. It is considered that the amount of water supplied from the water vapor in the atmosphere or the water adhering to the substance is sufficient. At this time, the inorganic electrolyte substance coexisting with the iron powder reacts with the moisture, ionizes it, and plays the role of promoting the oxidation reaction of the iron powder. Therefore, oxygen is captured only by iron powder, but at the same time, the presence of electrolyte substances is also considered essential. Further, as the thermoplastic resin, one should be selected that has the property of permeating oxygen gas, such as polyolefins. This is because oxygen molecules permeate and diffuse through the resin, reach the iron powder contained therein, and are captured there. The iron powder and inorganic electrolyte used in the present invention are preferably fine particles with a particle size of 50 mesh or more. Filling amount is 50 to 800 parts of iron powder per 100 parts of resin.
part, the inorganic electrolyte material is preferably 1 to 160 parts, and the ratio of the iron powder to the inorganic electrolyte material is preferably 100:2 to 100:20. These restrictions regarding the powder diameter and filling amount are given from the viewpoints of processability during subsequent molding, mechanical strength of the molded product after processing, and oxidation efficiency. Here, as inorganic electrolyte substances, periodic table a,
Halides, carbonates, sulfates, nitrates, phosphates, etc. of groups a, b, and b are effective, but halides are preferable from the viewpoint of ease of ionization.
Moreover, from the viewpoint of economic efficiency, sodium chloride is considered to be optimal. As a means for uniformly mixing the iron powder and the inorganic electrolyte powder with the thermoplastic resin, the purpose can be achieved in a heated state, for example, using a high-speed mixer. The resin according to the present invention can be processed into sheets, films, bottles, containers, laminates, etc. by making full use of the inherent properties of thermoplastic resins, such as formability and mechanical strength. Moreover, the water resistance of the resin is not impaired in any way. In order to use the resin of the present invention as a packaging material, it is conceivable to process it into a laminated structure, for example.
In this case, an oxygen-impermeable synthetic resin such as nylon, polyester, polyvinylidene chloride, or metal foil is used as the outer layer to block oxygen in the atmosphere. The resin of the present invention may also be used as the interior material. In order to prevent the contents from coming into direct contact with the resin, it is also possible to use polyolefin or silicone film with good oxygen permeability as the innermost layer, or use a microporous film with air permeability. . It is also possible to integrally mold this laminated structure, and complex molded products such as bottles and containers can also be produced. When using a secondary processing method, a method may be considered in which a film is formed using the resin of the present invention and then a film having predetermined properties is attached to both sides of the film by post-processing. When the resin is used as a packaging container, whether it is a film or a bottle, it is unlikely that the food or medicine content will be chemically altered. Hereinafter, a packaging container will be manufactured using the thermoplastic resin based on the present invention, and changes in oxygen concentration within the container will be specifically explained using examples. Example 1 Low density polyethylene 100 as thermoplastic resin
250 parts of iron powder (200 mesh or more) and 30 parts of sodium chloride (200 mesh or more) are mixed in a super mixer at a temperature of 110°C, made into pellets with an extruder pelletizer, and the pellets are made into 200 μm thick pellets with an extrusion type T-die molding machine. Make a thick sheet. Glass 200ml
A 2 cm x 3 cm sheet piece and 0.2 g of cotton cloth containing 2 g of water were placed in a sealed container. The oxygen concentration in the container was tracked over time using a gas chromatograph, and the results are shown in the attached table. Example 2 Thermoplastic resin (A) having the same composition as Example 1,
Inflation with a three-layer structure using nylon (Toray CM5012) (B) and low-density polyethylene (Ube polyethylene FC19) (C), with (A) as the middle layer, (B) as the outer layer, and (C) as the inner layer. A film was formed. The average thickness of each layer is (A) 150μm, (B) 20μm, (C) 10μm
It was set as m. Using this film, a square bottom bag was made that was 20 cm long, 10 cm wide, and 2 cm thick at the bottom. 0.2 g of cotton cloth containing 2 g of water was placed in this bag and the opening was sealed. The oxygen concentration in the bag was tracked in the same manner as in Example 1, and the results shown in the attached table were obtained. Example 3 A 20 μm aluminum foil was fused to one side of the 200 μm thick film obtained in Example 1 by hot press molding, and a 120 μm porous film (Tokuyama Soda NF sheet) was attached to the other side using vinyl acetate. It was attached with an adhesive to form a three-layer structure. Using this film, we made a square bottom bag with a length of 20 cm, a width of 10 cm, and a bottom thickness of 2 cm. There are 2 in this bag
0.2 g of cotton cloth containing 1 g of water was put in and the opening was sealed. The oxygen concentration in the bag was tracked in the same manner as in Example 1, and the results shown in the attached table were obtained. 【table】

Claims (1)

[Claims] 1 Add 50-400 parts of finely powdered iron powder of 50 mesh or more to 100 parts of thermoplastic resin, and add 2-20% of sodium chloride powder by weight to the iron powder,
An oxygen-absorbing resin composition made of a uniform mixture and filling of these materials.