JPH09117660A - Oxygen absorbing material and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve an oxygen absorbing capability and at the same time, produce an oxygen absorbing material at a low cost by preparing a mixture of aluminum and at least, one selected from an alkali metal oxide and an alkaline earth metal oxide. SOLUTION: This oxygen absorbing material used for inhibiting the oxidation and degradation of food is prepared using aluminum and at least, one selected from an alkali metal oxide and an alkaline earth metal oxide. The alkali metal oxide to be preferably used is lithium oxide, sodium oxide or potassium oxide. The alkaline earth metal oxide to be used is magnesium oxide or calcium oxide. In addition, the aluminum particle content is set in the range of 70wt.% or more and 95wt.% or less of the total mixture. The oxygen absorbing material of this type is manufactured by crushing and mixing the mixture using a ball mill.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an oxygen absorbing material and a method for producing the same.

[0002]

2. Description of the Related Art As a packaging technology for preventing oxidative deterioration of foods and the like, an oxygen barrier packaging material such as aluminum foil or polyvinylidene chloride is used to prevent oxygen from entering from the outside, and the oxygen inside the packaging bag is replaced with nitrogen. There is a method of replacing with an inert gas such as carbon dioxide. Furthermore, in the case of gas replacement, in order to remove a small amount of oxygen remaining without being replaced, an oxygen absorbing material is optionally sealed inside the packaging bag. As an oxygen absorbing material for that purpose, an inorganic material such as iron powder or an organic material mainly containing ascorbic acid is known. In order to prevent the oxidative deterioration of the contents, it is necessary to quickly remove the internal oxygen after packaging, but ascorbic acid-based products have a slow reaction, so their use is limited. On the other hand, the iron-based oxygen absorbing material has a stable ability because it is an inorganic material, is excellent in hygiene, and is widely used for packaging contents. However, the oxygen-absorbing material is a part of the packaging bag for protecting the contents, and it has been demanded that the oxygen-absorbing material has an effective oxygen-absorbing ability in a smaller amount and is inexpensive.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to provide an inexpensive oxygen absorbing material having a high oxygen absorbing ability.

[0004]

[Detailed description of the invention]

Aluminum used for the oxygen absorbent of the present invention is known as a metal that is easily oxidized, and it is considered that this effect is used as an oxygen absorbent. However, a dense oxide film is likely to be formed on the surface of aluminum, and this oxide film prevents the invasion of oxygen into the inside of aluminum, so that the oxidation inside aluminum does not proceed.
Therefore, metallic aluminum could not be used as it is as an oxygen absorbent.

As a result of intensive studies on the removal of the oxide film on the surface of aluminum, the present inventors have found that by mixing an alkali metal oxide and / or an alkaline earth metal oxide with metal aluminum, Since the oxide film is modified and the oxidation of aluminum proceeds to the inside, it has been found that it becomes an oxygen absorbent having a high oxygen absorption capacity, and the present invention has been completed.

By mixing aluminum with alkali metal oxides and / or alkaline earth metal oxides in this way, the alkali metal oxides and / or alkaline earth metal oxides react with the oxide film of metal aluminum. It is considered that oxygen can enter the inside of aluminum metal by forming an aluminate or a double oxide. Furthermore, it is considered that the alkali metal oxide and the alkaline earth metal oxide react with aluminum and oxygen inside the package to form an aluminate.

Examples of the alkali metal oxide used in the present invention include lithium oxide, sodium oxide and potassium oxide. Examples of the alkaline earth metal oxide used in the present invention include magnesium oxide, calcium oxide, strontium oxide and the like. These oxides may be used alone or as a mixture, if necessary. Of the above metal oxides, magnesium oxide and calcium oxide are particularly preferable because they are easy to handle as a simple substance. The alkali metal oxide or the alkaline earth metal oxide may be in any state such as granular, powdery or lumpy state, and is not particularly limited, and can be selected according to the pulverization and mixing method.

The aluminum that can be used in the present invention does not have to be particularly highly purified, and may be in the form of powder, granules or lumps, like the metal oxide, and is suitable for pulverization and mixing. A shape can be used.

A mixture of aluminum and an alkali metal oxide or an alkaline earth metal oxide is preferably used as a particulate or powdery mixture. Regarding the mixing ratio of aluminum and metal oxide, the higher the aluminum content, the higher the oxygen absorption amount, but when the aluminum content is 95% by weight or more, the effect of the alkali metal oxide or the alkaline earth metal oxide is It becomes insufficient and the oxygen absorption capacity decreases. On the other hand, when the mixing ratio of aluminum decreases, the initial reactivity improves, but the final oxygen absorption amount itself decreases, which is not preferable. From these points, the content of aluminum varies depending on the molecular weight of the mixed alkali metal oxide or alkaline earth metal oxide,
The amount is preferably 70% by weight or more and 95% by weight or less, and more preferably 80% by weight or more and 90% by weight or less.

The above aluminum and the alkali metal oxide and / or the alkaline earth metal oxide may be mixed as they are when powdery ones are used, but they are ground by a ball mill including a grinding process at the time of mixing. Mixing is desirable. By this operation, a part of the oxide film on the surface of aluminum can be mechanically destroyed, whereby the contact between aluminum and the alkali metal oxide or the alkaline earth metal oxide is improved and the reactivity is increased. Further, the granular aluminum is preferably used after the oxide film already formed on the surface of the aluminum is removed by washing the aluminum with an acid or alkali aqueous solution before pulverizing and mixing.

When the aluminum of the present invention is pulverized into fine particles, it becomes highly reactive and can act as a more effective oxygen absorber. The crushed aluminum particles are preferably 500 μm or less, more preferably 100 μm or less. Further, it is preferable that the pulverization and mixing of aluminum and the alkali metal oxide or the alkaline earth metal oxide be carried out in an atmosphere of an inert gas such as nitrogen gas or argon gas.

The oxygen-absorbing material of the present invention can be used by enclosing it in an air-permeable packaging material obtained by perforating paper / polyethylene, polyester / paper / polyethylene or the like.

[0014]

[Function] Alkali metal oxides and alkaline earth metal oxides are considered to form double oxides by reacting with the dense aluminum oxide on the aluminum surface either directly or as hydroxides that have reacted with water in the package. To be This allows oxygen to diffuse into the metal aluminum, where oxygen reacts with aluminum and functions as an oxygen absorbing material.

Further, it is considered that the alkali metal oxide and the alkaline earth metal oxide absorb oxygen when they directly contact with aluminum to form a double oxide.

[0016]

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

<Example> 85 parts of powdered aluminum (manufactured by Kanto Chemical Co., Inc.) and 15 parts of calcium oxide (manufactured by Kanto Chemical Co., Ltd.) as an alkaline earth metal oxide were placed in a ball mill in which nitrogen gas was substituted, The oxygen absorbing material of the present invention was obtained by pulverizing and mixing for 6 hours. The particle size of the mixture after grinding is 3
It was 0 μm. 1 g of this oxygen-absorbing material was placed in a perforated paper / polyethylene wrapping material which was enclosed in an aluminum pouch with 600 cc of air. In addition, absorbent cotton was impregnated with 1 g of water to fill the aluminum pouch with water and enclosed. The air in the aluminum pouch was sampled at predetermined time intervals, and the oxygen concentration was measured with an oxygen concentration meter. The results are shown in Table 1. From these results,
It can be seen that the oxygen concentration inside the pouch has decreased and oxygen is being absorbed.

Comparative Example An oxygen absorbing material for comparison was produced in the same manner as in Example except that 100 parts of powdered aluminum (manufactured by Kanto Chemical Co., Inc.) was used in Example, and the oxygen concentration was the same as in Example. Was measured. The results are shown in Table 1.

[0019]

[0020]

According to the present invention, it is possible to provide an inexpensive oxygen absorbing material having a high oxygen absorbing ability.

Claims (5)

[Claims] 1. Aluminum and at least one selected from alkali metal oxides and alkaline earth metal oxides.
An oxygen-absorbing material comprising a mixture with two metal oxides. 2. The oxygen absorbent according to claim 1, wherein the alkali metal oxide is lithium oxide, sodium oxide, or potassium oxide. 3. The oxygen absorbing material according to claim 1, wherein the alkaline earth metal oxide is magnesium oxide or calcium oxide. 4. The aluminum content of the mixture is 70%.
The oxygen absorbing material according to claim 1, wherein the oxygen absorbing material is in the range of not less than 95% by weight and not more than 95% by weight. 5. Aluminum and at least one selected from alkali metal oxides and alkaline earth metal oxides.
A method for producing an oxygen absorbing material, which comprises pulverizing and mixing two metal oxides with a ball mill.