JPS61157343A - Oxygen absorbent - Google Patents

Abstract

PURPOSE:To obtain an oxygen absorbent excellent in an oxygen absorbing speed and oxygen absorbing capacity and generating no noxious gas, by compounding pyrogallol, an alkaline compound, activated carbon and a moisture imparting compound. CONSTITUTION:The compounding ratio of four components, that is, pyrogallol, an alkaline compound, a moisture imparting compound and activated carbon is set, on a wt., basis, to 2/0.5-5/1-5/0.2-10, most pref., 2/1/2/1. As the alkaline compound, hydroxide or carbonate of an alkali metal or an alkaline earth metal, especially, Ca(OH)2 is pref. and, as the moisture imparting compound, NaH2PO4.12H2O or NaCO3.10H2O is used. As activated carbon, a coarse one with a particle size of about 4-32 mesh is effective. Thus obtained oxygen absorbent generates no noxious gas and has a high initial oxygen absorbing speed and the excellent lasting property in oxygen absorbing capacity and can be utilized in various fields, as a preservative for foods or an oxidation inhibitor for a drug.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to an oxygen absorbent that selectively absorbs only oxygen in a mixed gas by contacting with a mixed gas containing oxygen such as air.

[Prior art and its problems]

In recent years, methods of using oxygen absorbers have been developed to preserve the quality of foods. According to this method, an oxygen absorber is placed in a food package together with the food and brought into contact with the air inside the food package, thereby absorbing the oxygen in the package and preventing food quality deterioration caused by the presence of oxygen over a long period of time. can do. The oxygen absorbent for this purpose must (1) have a fast oxygen absorption rate, (2) have a long oxygen absorption capacity, and (3) not generate harmful gases. Conventionally, as this type of oxygen absorbent, inorganic oxygen absorbers using reducing iron powder, hydrosulfide, etc., and organic oxygen absorbers using ascorbic acid, glucose oxidase, etc. are known. However, iron-based oxygen absorbents have a problem in the sustainability of their oxygen absorption capacity, and also have the disadvantage of generating hydrogen gas when absorbing oxygen. Oxygen absorbers using hydrosulfide have the disadvantage of generating harmful sulfur dioxide gas due to decomposition of the components. In addition, other oxygen absorbents have the disadvantage that the initial oxygen absorption rate is slow. [Objective of the Invention] The present invention eliminates the above-mentioned disadvantages of the oxygen absorbent, and has a high initial oxygen absorption rate. The purpose of the present invention is to provide an oxygen absorbent that has excellent sustainability of oxygen absorption capacity and does not generate harmful gases.

[Key points of the invention]

In summary, the present invention relates to an oxygen absorbent characterized by containing pyrogallol, an alkaline compound, activated carbon, and a moisture-donating compound.

The inventors of the present invention have conducted intensive studies to find an oxygen absorbent that has the above-mentioned excellent oxygen absorption ability and does not generate impurity gas components such as hydrogen. Weird shift, yoa7.
KA, 1 I ■ Tsuyo life. □We have discovered that an oxygen absorbent whose main component is a water-donating compound does not generate impure gas components and has excellent oxygen absorption ability.

Pyrogallol used in the present invention is also called 1,2,3-benzenetriol, and is a white powder at room temperature.

When this pyrogallol reacts with oxygen, it absorbs oxygen, but its oxygen absorption ability is further improved by coexisting with an alkaline compound, a moisture-donating compound, and activated carbon. The oxygen absorption rate is extremely high, approximately 2.0 times the oxygen absorption rate of conventional oxygen absorbers whose main component is iron powder, and approximately 1.5 times that of oxygen absorbers whose main component is ascorbic acid. It was also found that the sustainability of its performance was superior to that of oxygen absorbers whose main ingredient is iron powder.

Alkaline compounds used in the oxygen absorbent of the present invention include hydroxides, carbonates and bicarbonates of alkali metals and alkaline earth metals, such as Ca(OH)z.

ゞaOH・KOH・Mg(OH)2ba′. 0°・3′.

0°4d"゛1.Particularly preferred is Ca(OH)z0.Moreover, the moisture-donating compound is one that absorbs moisture or contains it in the form of a hydrate, and is an oxygen absorbent. Compounds that do not generate impure gas by reacting with pyrogallol, alkaline compounds, etc., are used.Such compounds include sodium dihydrogen phosphate, dihydrogen phosphate, dihydrogen phosphate, 7 and earthworks water salt, magnesium hydrogen phosphate tri- and superhydrate salt, sodium carbonate 117 and decahydrate salt,
Examples include tri- and trihydrate salts of magnesium carbonate, preferably NaHzPO<-12H20.

Na2CO3・1OHzO, Na2COa・7HzO
In order to maintain and exhibit the excellent oxygen absorption ability of pyrogallol for a long time, the activated carbon coexisting in the absorbent of the present invention must have a coarse particle size, that is, a crushed or pellet form of 4 to 32 mesh. It is extremely effective to use activated carbon. Powdered oxygen absorbers such as those of the present invention generally coagulate and solidify due to moisture generated from moisture-donating compounds as oxygen absorption progresses, and oxygen absorption occurs only on the surface, making it difficult to use for long periods of time. This is because the oxygen absorption capacity may decrease. However, by using coarse-grained crushed activated carbon as the activated carbon, the effective surface area of the oxygen absorbent can be increased, and furthermore, it is possible to prevent coagulation and solidification, and as a result, the oxygen absorption capacity can be maintained for a long time. It is possible. Further, by using a mixture of coarse activated carbon and fine activated carbon, it is possible to obtain an oxygen absorbent that further improves the initial oxygen absorption rate and has excellent sustainability of oxygen absorption capacity.

The effect of improving the absorption characteristics of the oxygen absorbent by adjusting the particle size of the active bed as described above can only be obtained with the pyrogallol-containing oxygen absorbent of the present invention. Therefore, if coarse-grained activated carbon is used, the initial absorption capacity will decrease, and if fine-powdered activated carbon is used, it will often have the opposite effect, such as shortening the life of the oxygen absorber. I can't stand it.

The oxygen absorbent of the present invention contains the four essential components of pyrogallol, an alkaline compound, a moisture-donating compound, and activated carbon as described above, and exhibits a strong oxygen absorption ability only when all of these components are present. The blending ratio of these four components,
That is, the blending ratio of pyrogallol/alkaline compound/moisture-donating compound/activated carbon can be arbitrarily selected, but preferably 270.5 to 5/1 to 5102 to 5102 by weight.
10. More preferably 2/1/2/1.

[Embodiments of the invention]

The present invention will be specifically described below with reference to Examples and Comparative Examples.

Compositions containing pyrogallol, an alkaline compound, a moisture-donating compound, and activated carbon as listed in Table 1 below were prepared, each was sealed in a sealed container, and the change in oxygen absorption over time was determined.

The results are shown in Table 1.

Table 1 shows that the oxygen absorbents of Examples 1 to 5 have extremely high oxygen absorption rates compared to the oxygen absorbents of Comparative Examples 1 to 5.

Comparative Examples 1 to 3 have compositions lacking any one of an alkaline compound, a moisture-donating compound, and activated carbon, but in all cases, the oxygen absorption ability is inferior to that of Example 1. This shows that the four types of components in the present invention are essential.

Next, an experiment was conducted to demonstrate the sustainability of the oxygen absorbent's ability to absorb oxygen. In this experiment, an oxygen absorbent with the composition shown in Table 2 was sealed with air in a sealed tank with an internal volume of 500 mm, and the amount of residual oxygen was measured every 5 hours, and new air was introduced into the tank. The measurement was repeated three times. The results obtained are shown in Table 2.

From Table 2, it can be seen that the oxygen absorbent of Example 6 has a formulation composition that is the basis of the present invention, but exhibits a much higher sustainability of oxygen absorption capacity than that of Comparative Example 6.
In addition, Example 7 shows that the sustainability of oxygen absorption capacity was improved by using activated carbon with a coarse particle size as the activated carbon. 3
It also showed stable oxygen absorption ability in the second measurement.

Furthermore, Example 8 is an example in which a mixture of coarse activated carbon and fine powder activated carbon is used, and the amount of oxygen absorbed increases quickly and the life as an oxygen absorbent is long. ] In the present invention, by combining pyrogallol, an alkaline compound, a moisture-donating compound, and activated carbon, an oxygen absorbent having excellent oxygen absorption ability and not generating impurity gas components such as hydrogen gas can be obtained. Can be done. The details of the oxygen absorption mechanism are still not well understood.

Due to this excellent oxygen absorption ability, the oxygen absorbent of the present invention is not only useful for food packaging, but also for preventing the harmful effects caused by the presence of oxygen, such as rust prevention of metal products, prevention of deterioration of chemical products, and prevention of oxidation of pharmaceutical products. Therefore, it can be applied to various uses.

In particular, the oxygen absorbent of the present invention does not generate hydrogen gas like an oxygen absorbent whose main component is iron powder, or generate sulfur dioxide gas like an oxygen absorbent whose main component is hydrosulfide. Since it does not generate impure gas components, it is also effective as an oxygen remover in various gas analyzers.

Furthermore, in the oxygen absorbent of the present invention, the oxygen absorbing ability can be sustained over a long period of time by using coarse-grained crushed or pellet activated carbon as the activated carbon. This coarse-grained activated carbon is used to prevent the powdered oxygen absorbent from condensing and solidifying, and for this purpose it is thought that simple fillers such as sawdust that do not participate in the oxygen absorption reaction are also effective. Addition of sawdust, etc. is not appropriate as it not only increases the volume of the oxygen absorbent but also may become a source of impurity gas.Furthermore, it is not appropriate to add substances such as coarse activated carbon and fine powdered activated carbon. When used in combination, the oxygen absorption rate rises quickly and the high oxygen absorption capacity can be maintained stably for a long time.For this reason, the oxygen absorbent of the present invention can be used in mechanical equipment that dislikes the presence of oxygen. It can be used as an oxygen scavenger for many years.

Claims (1)

[Scope of Claims] 1) An oxygen absorbent comprising pyrogallol, an alkaline compound, activated carbon, and a moisture-donating compound. 2) In the oxygen absorbent according to claim 1,
An oxygen absorbent comprising crushed or pelleted activated carbon having a particle size of 4 to 32 mesh. 3) In the oxygen absorbent according to claim 1,
An oxygen absorbent characterized by blending activated carbon in the form of crushed or pellets with a particle size of 4 to 32 mesh and activated carbon in the form of fine powder.