JPS6253222B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to oxygen scavenging compositions.
More specifically, the present invention relates to a composition that has the effect of absorbing oxygen when it comes into contact with oxygen. According to the present invention, a composition having an action as an oxygen absorber or a heating element is provided. The oxygen scavenging composition according to the present invention is made to coexist in a sealed container with food or other materials that would rot, deteriorate, or deteriorate due to contact or reaction with oxygen, thereby effectively removing oxygen in the container. It has the effect of preventing spoilage, alteration, and deterioration of foods, etc. by absorbing them. Further, the oxygen scavenging composition according to the present invention generates heat by absorbing oxygen, and by utilizing this action, it can be used as a heat generating body. Conventionally, methods for preserving food products to prevent spoilage, deterioration, and deterioration include (1) refrigeration, (2) inert gas substitution using an inert gas such as carbon dioxide, ethylene, or nitrogen, and (3) preservation. There are methods such as the vacuum packing method, in which the raw material is reduced to a vacuum, and there is also a method of adding food additives such as antioxidants and anti-corrosion agents to the food. However, in recent years, the use of food additives for food preservation has become subject to strict legal restrictions and regulations due to the adverse effects they have on animals, especially on the human body. On the other hand, among the above preservation methods, the refrigeration method requires very large refrigeration equipment and complicated operations, and is also economically expensive. In addition, the inert gas substitution method and the vacuum packing method not only require complicated operations, but also have insufficient storage stability. Therefore, if a simple and inexpensive method for preserving food could be provided, its industrial value would be extremely large. When preserving food, mold, bacteria, insects, and double bonds in the food are considered to be the causes of spoilage, deterioration, and deterioration, but most of these survive, reproduce, or undergo oxidation reactions in the presence of oxygen. This results in rot, deterioration, and deterioration. Therefore, if oxygen in airtight containers can be selectively removed during food storage, the survival and reproduction of mold, bacteria, insects, etc. can be prevented, and oxidation reactions of double bonds in foods can be suppressed. It becomes possible. Conventional methods for preserving food by removing oxygen in packaging containers include (1) a method using hydrosulfite as the main agent, calcium hydroxide or sodium bicarbonate, activated carbon, and water (Japanese Patent Publication No. 47 (2) method using sulfite and activated carbon (see Japanese Patent Publication No. 51-12471). However, the former method causes a rapid reaction and is therefore difficult to handle.
It also has the disadvantage of requiring water.
Furthermore, the latter method has the disadvantage that generation of sulfur dioxide gas cannot be avoided. On the other hand, by combining iron carbide and alkali sulfide, a composition having an exothermic effect can be obtained (see Japanese Patent Application Laid-Open No. 108382/1982), and by combining activated carbon and alkali sulfide. It is possible to obtain a composition that has an exothermic effect even when
108383) is known. All of these exothermic compositions are intended to draw in oxygen and utilize the heat of reaction, but it is difficult to broadly control the amount of heat generated and the rate of heat generated by these compositions. The present inventors have overcome the shortcomings of the conventional proposed methods and selectively removes oxygen in the packaging of foods, medicines, equipment, etc., and allows the survival and proliferation of mold, bacteria, insects, etc. in the contents of the packaging. It also prevents spoilage caused by oxidation reactions,
The present invention was achieved as a result of research into an oxygen scavenging composition that can be applied to the safe and simple preservation of food products by suppressing deterioration or deterioration, and can also be used as a heating element with a wide range of applications. According to the invention, it comprises (a) an alkali metal sulfide and (b) silica-magnesia, or (a) an alkali metal sulfide, (b) a silica-magnesia and (c) a filler. An oxygen scavenging composition is provided comprising: The oxygen scavenging composition according to the present invention uses inexpensive raw materials, can freely control the rate and amount of heat generation, smoothly absorbs oxygen, and does not generate dangerous gases such as sulfur dioxide gas. Furthermore, there is no need to add free (liquid) water, making it extremely clean. Moreover, most of the oxygen scavenging compositions of the present invention change color due to absorption of oxygen.
It is possible to observe whether oxygen absorption has taken place by observing a change in color, and this can also be used to determine the freshness of the packaged contents. On the other hand, the oxygen scavenging composition of the present invention can also be used as a detection substance that detects the presence of oxygen in a certain atmosphere by utilizing the color change. Furthermore, by utilizing its exothermic action, the oxygen scavenging composition of the present invention can be used as a heating element, for example, as a heating or heat-retaining material. The oxygen scavenging composition of the present invention described above can be used in an extremely wide range of fields by utilizing its excellent effects. Examples are listed below. (i) Preventing the oxidation of oils and fats and oil-containing substances; For example, instant noodles, karinto, peanuts, butter peanuts, fried beans, popcorn, potato chips, chiyocolate, eel feed, fried rice crackers, shaved bonito flakes, rice bran, powdered milk,
Preventing oxygen deterioration of oils and fats and oil-containing products such as refined rice, dairy products, wheat germ, confectionery, and medical foods; (ii) Preventing deterioration of aroma and taste of foods; For example, bread crumbs, dried vegetables, dried seafood, dried seaweed, Dried shiitake mushrooms, dried mushrooms, dried fruits,
Preventing quality deterioration of foods such as seaweed, coffee beans, black tea, green tea, etc. whose color, flavor, and flavor deteriorate due to oxygen; (iii) Preservative, insect repellent, tooth repellent, and mold repellent; For example, bread, rice cakes, fresh sweets, and vegetables. (iv) Prevention of deterioration and spoilage of various fresh foods such as fruits, fish, beef, pork, and poultry due to mold, bacteria, and insects; (iv) Prevention of deterioration of various organic materials; For example, prevention of deterioration of various organic materials; Prevention of deterioration due to alteration and discoloration caused by oxygen; (v) Rust prevention of metals; For example, metal products such as iron, zinc, copper, and aluminum, electrical products using these, parts, household equipment, musical instruments, precision instruments, etc. Rust prevention; (vi) Use as a heating element; For example, for medical purposes such as heating pumps and insulation materials;
Food heating materials, cold protection materials, anti-freezing materials, oxygen leak detection substrates; The above examples are merely illustrative, and the oxygen scavenger of the present invention can be used in other fields as well due to its oxygen absorption and heat generation properties. It can be widely used in any field where its action can be utilized. It can also be used to store books and prevent dust pollution. Furthermore, as mentioned above, the oxygen scavenging compositions of the present invention are often white, very pale pink, yellow, or very pale green, but these often change color when absorbing oxygen.
For example, a white color becomes gray, and a light green color becomes dark green, green, or black-green. Utilizing these color changes, it is possible to test the presence or absence of oxygen and to observe whether oxygen has been absorbed or not.Using this, it is also possible to determine the freshness of the packaged contents. Can be distinguished. The alkali metal sulfides of component (a) in the composition of the present invention include lithium, sodium, potassium,
Refers to sulfides such as rubidium and cesium and their hydrates. Examples include Li ₂ S, Na ₂ S,
K ₂ S, Rb ₂ S, Cs ₂ S and an alkali polysulfide compound [for example, represented by the formula MSX (where M is an alkali metal and X is a positive number of 1 to 10, preferably 1 to 5)] Can be mentioned. Examples of such alkali polysulfides include Na ₂ S ₂ , K ₂ S ₂ , Rb ₂ S ₂ ,
Cs ₂ S ₂ , Na ₂ S ₃ , Rb ₂ S ₃ , Na ₂ S ₄ , CsS ₂ , Na ₂ S ₅ ,
Examples include K ₂ S ₅ , K ₂ S ₆ , Rb ₂ S ₆ and Cs ₂ S ₆ . Furthermore, alkali metal sulfides are hydrated, e.g.
Na ₂ S・9H ₂ O, Na ₂ S.6H ₂ O, Na ₂ S・5.5H ₂ O,
Na ₂ S・5H ₂ O, Na ₂ S・4.5H ₂ O, K ₂ S・2H ₂ O,
K ₂ S・5H ₂ O, K ₂ S ₄・1/2H ₂ O, Rb ₂ S・4H ₂ O,
May be CsS・4H ₂ O and CsS ₂・H ₂ O,
That may be preferable in some cases. Among these, sodium sulfide, potassium and their hydrates are preferred, and sodium sulfide nonahydrate (Na ₂ S.
9H ₂ O) is the most preferred because it is effective, inexpensive and easily available. The alkali metal sulfide is a relatively stable compound that easily absorbs oxygen and is not oxidized even when exposed to an oxygen atmosphere at room temperature.
(b) When combined with silica and magnesia, it can easily absorb oxygen even at room temperature. The silica/magnesia component (b) corresponds to ores containing silica and magnesia as main components and synthetic silica/magnesia. Particularly suitable are those containing silica/magnesia in an amount of 50% by weight or more, preferably 60% by weight or more, particularly preferably 65% by weight or more. Examples of such ores include talc, whose main component is hydrated magnesium silicate, olivine (holsterite), indica, asbestos, and diamonite. Furthermore, magnesium metasilicate salts and the like are also included. Furthermore, as for synthetic silica/magnesia, if silica and magnesia are included, the ratio of silica and magnesia can vary widely, for example, 1:99 to 99:99 by weight.
1, preferably a ratio of 95:5 to 5:95. Silica and magnesia as component (b) in the present invention may be commercially available products as they are, or may be calcined. However, there is no particular need for firing. especially
When the alkali metal sulfide as component (c) is an anhydrous salt, good results can be obtained if silica/magnesia is used in a hydrated form without being calcined. The ratio of (a) alkali metal sulfide and (b) silica/magnesia in the oxygen scavenging composition of the present invention can be varied depending on the intended properties and use of the composition. For example, if you wish to increase the oxygen absorption rate and heat generation rate, you can generally increase the ratio of component (b) to component (a), but do not increase the ratio of component (b) to component (a). The amount becomes smaller. On the other hand, in order to slow down the oxygen absorption rate, the proportion of component (b) may be reduced. Generally, silica/magnesia is suitably used in an amount of 0.01 part by weight or more, preferably 0.05 part by weight or more, per 1 part by weight of the alkali metal sulfide, and preferably 0.1 part by weight or more for good oxygen absorption. On the other hand, the upper limit of silica and magnesia is
100 parts by weight or less, preferably 50 parts by weight or less, particularly preferably 20 parts by weight, per 1 part by weight of alkali metal sulfide.
Parts by weight or less are advantageous. In the present invention, (c) a filler can be further added to (a) an alkali metal sulfide and (b) silica/magnesia. By adding a filler, it is possible to improve the rate of oxygen absorption, control of the amount absorbed, air permeability, etc. Such fillers may be either inorganic or organic as long as they are chemically inert to (a) alkali metal sulfides and (a) silica/magnesia. Particularly preferred are those that are insoluble or poorly soluble in water. Examples of such fillers include carbon products such as activated carbon and graphite; metal carbides such as silicon carbide, silicon nitrogen, and iron carbide; metal oxides such as iron oxide, nickel oxide, magnesium oxide, and calcium oxide; glass. Examples include inorganic fillers such as powder, organic fillers such as cellulose, and synthetic resin powder (eg, polyethylene, polyaramid, powder). In the present invention, the filler (c) is advantageously used in an amount of 0.001 part by weight or more, preferably 0.01 part by weight or more, based on 1 part by weight of the total of (a) alkali metal sulfide and (b) silica/magnesia. It is. The upper limit of the amount of filler used is limited by the fact that if it is used in too large a quantity, the amount of oxygen absorbed per unit weight of the oxygen scavenging composition decreases and becomes economically undesirable, but in general, (a) sulfidation of alkali metal and (b) silica.
Total magnesia (per part by weight, 50 parts by weight or less,
It is sufficient that the amount is preferably 20 parts by weight or less, particularly preferably 10 parts by weight or less. In the present invention, (d) in a water-containing or hydrated state, such as a composition containing (a) an alkali metal sulfide and (b) silica/magnesia (or these and (c) a filler). By containing water, the oxygen absorption rate and amount of oxygen absorption are further increased.
Moreover, the amount of heat generated can be increased. Such "hydrous or hydrated water" refers to water that is adsorbed or impregnated with any one or more of the components (a), (b), and (c). and refers to water as a hydrate, and does not refer to liquid water that is in a fluid state in appearance. For example, (a) water of crystallization in hydrates of alkali metal sulfides (e.g. Na ₂ S・9H ₂ O,
Na ₂ S・6H ₂ O, K ₂ S・2H ₂ O, K ₂ S・5H ₂ O, etc.),
Examples of water in component (d) include (b) water and crystal water impregnated or adsorbed in silica/magnesia, and (c) water and crystal water impregnated or adsorbed in a filler. Further, as the component (d), water, it is possible to use, for example, a compound having water of crystallization. Such compounds include, for example, Na ₂ SO ₄ .10H ₂ O, Al ₂ O(OCH ₃ ) ₄ .
4H ₂ O, Al ₂ (SO ₄ ) ₃・Na ₂ SO ₄・24H ₂ O, Al ₂
( _SO4 ) ₃・16~ _18H2O , _CaSO4・_2H2O , Co
( _OOCH3 ) ₂・_4H2O , _FeSO4・_7H2O , Mg
(OOCH ₃ ) ₂・4H ₂ O, MgSO ₄・7H ₂ O, KOOCCH
(OH)CH(OH)COONa・_4H2O 、 _SiO2・
nH ₂ O, Na (OOCH ₃ ) ₂・3H ₂ O, Na ₃ PO ₄・12H ₂ O
Among these, Na ₂ SO ₄・
10H ₂ O is preferred because it is easily available and inexpensive. In particular, water in component (d) is preferably used as crystal water of component (a), crystal water of component (b), or crystal water of component (c). The amount of water as component (d) is suitably in the range of 0.01 to 50 parts by weight, preferably 0.04 to 30 parts by weight, per 1 part by weight of component (a) in the entire composition. In the present invention, the oxygen scavenging composition may be in any form. For example, each of the components (a) to (c) may be finely powdered, and the mixture may be simply mixed using a mortar, agate bowl, sieve machine, ball mill, gearcon powder, internal mixer, etc. It can be used as a powder, such as one that has been crushed and mixed, or the mixed powder can be made into pellets, pieces, rods, blocks, and sheets using a tablet machine, extrusion molding machine, roll molding machine, etc. It may also be a molded product. At that time, binders and lubricants that are normally used for powder molding can also be used. Examples of such binders include starch, carboxymethylcellulose, high molecular weight polymers such as polyvinyl acetate, polyolefin, and polyvinyl alcohol, and examples of lubricants include various stearic acid derivatives. The oxygen-scavenging composition of the present invention can be used as it is in powder form or molded as described above, or it can be placed in a bag made of air-permeable packaging material, such as cellophane, various synthetic resin films, paper, etc. It can also be used. As long as it is breathable, the material and structure of the packaging material can be varied. The oxygen scavenging composition of the present invention can be used for purposes such as removing oxygen, reducing oxygen content, and detecting the presence of oxygen, and the amount used can be determined as appropriate depending on the purpose and use. can be selected, in particular,
It can be advantageously applied to holding various foods, medicines, metals, and precision equipment that deteriorates or changes in quality due to oxygen. Furthermore, it can be used as a heating element or a heat insulating material. Hereinafter, the present invention will be explained in detail with reference to Examples. Examples 1 to 12 0.4 g of various alkali sulfides, silica/magnesia as component (b), and filler (c) were mixed and ground in an agate pot under a nitrogen atmosphere, and the mixture was heated at 20°C under one atmosphere of oxygen. When exposed, changes in oxygen absorption and color as shown in Table 1 were observed.

[Table] Comparative Example 1 When 0.4 g of commercially available sodium sulfide (Na ₂ S, 9H ₂ O) was crushed into small pieces under a nitrogen atmosphere and left in an oxygen atmosphere of 1 atm at 20°C for 20 hours, substantial amounts of oxygen were removed. No significant absorption was observed. Comparative Example 2 The same procedure as in Example 4 was repeated except that 1.0 g of calcium oxide (CaO) was added instead of silica-magnesia, and 5 c.c. of oxygen was absorbed.

Claims (1)

[Scope of Claims] 1. An oxygen scavenging composition comprising (a) an alkali metal sulfide and (b) silica/magnesia. 2. An oxygen scavenging composition comprising (a) an alkali metal sulfide, (b) silica/magnesia, and (c) a filler. 3. An oxygen scavenging composition comprising (a) an alkali metal sulfide, (b) silica-magnesia, and (d) water in a hydrous or hydrated state. 4. An oxygen scavenging composition comprising (a) a sulfide of an alkali metal, (b) silica-magnesia, (c) a filler, and (d) water in a hydrous or hydrated state.