JPH0235686B2 - - Google Patents

Description

[Detailed description of the invention]

It is well known that trace amounts of chlorine dioxide are effective as deodorizers, preservatives, antifungal agents, disinfectants, and disinfectants. Granular compositions are commercially available as household or commercial products. The performance required of these chlorine dioxide-containing products is that the contents remain stable during distribution or storage, that they can be used easily and stably, and that they are compatible with the purpose of use. and that an effective amount of chlorine dioxide is effectively generated. Taking the use of such products in refrigerators as an example, the concentration of chlorine dioxide gas that is effective for deodorizing or preventing odors in refrigerators is approximately 0.01 to 1.5PPm.
It is. If the concentration of chlorine dioxide gas is less than about 0.01PPm, it will not be possible to sufficiently deodorize the refrigerator.
If it significantly exceeds 1.5PPm, for example 5 to 10PPm, the desired deodorizing function will be fully achieved, but you will actually notice the odor of excess chlorine dioxide gas when you open the refrigerator door. . However, when the concentration of chlorine dioxide gas is 5PPm or higher, in addition to its deodorizing function, chlorine dioxide also has a disinfecting and sterilizing effect. For sterilization purposes, it is desirable to maintain the concentration of chlorine dioxide at about 5 to 15 PPm. In addition to maintaining chlorine dioxide gas at an appropriate concentration according to the intended function as described above, it is also important that this concentration remains stable for a certain period of time. For example, if chlorine dioxide is consumed within a short period of time, such as one week, gas generating powder must be replenished frequently. The above means that chlorine dioxide gas deodorizes and prevents odors not only in refrigerators, but also in the packaging of fresh foods such as vegetables, fruits, fish and shellfish, food display cases, the inside of cars, living rooms, kitchens, and washrooms. This applies to any place used for environmental purification purposes such as preservatives and sterilization. It is well known that an aqueous solution containing chlorine dioxide is stable in an alkaline region, and commercially available stabilized chlorine dioxide aqueous solutions for sterilization and disinfection are adjusted to a pH of 9 to 10. This solution, for example, involves absorbing gaseous chlorine dioxide in an aqueous solution of hydrogen peroxide and sodium carbonate;
It is adjusted so that the concentration of chlorine dioxide in the total aqueous solution is about 5% and the pH of the aqueous solution is about 9.0. This chlorine dioxide aqueous solution is activated in an acidic region,
Freed chlorine dioxide acts as an appropriate oxidizing agent,
Exhibits sterilizing and disinfecting effects. The principle that chlorine dioxide-containing substances are stable in alkaline regions and activated in acidic regions to generate chlorine dioxide gas is also utilized in powdered or granular chlorine dioxide-containing compositions. The composition described in Japanese Patent No. 72808 is based on this principle, in which a powdery solid composition is prepared by adsorbing an alkaline aqueous solution containing chlorine dioxide prepared as described above onto an alkaline adsorbent having a pH of 8.5-9.0. This is the gist of the invention. This composition is
Because it is alkaline, it does not generate chlorine dioxide gas as it is. Therefore, in this patent, when used, by mixing such a powder composition with an acidic powder substance, the overall pH is reduced to 6. The following method of generating chlorine dioxide gas has been proposed. According to this method, it is possible to produce a chlorine dioxide-containing composition that can be stored in a stable state for a long period of time. On the other hand, chlorine dioxide gas is generated only when mixed with acidic powder during use, and the intended function of the product can be utilized. It is inconvenient for people. Moreover, with this method, it is difficult to obtain a composition that stably generates a small amount of chlorine dioxide gas over a long period of time. Immediately after mixing the composition of this patent with acidic powder, a large amount of chlorine dioxide gas is generated, and stable gas generation is not observed over a long period of time, which limits its use. The present invention solves the above-mentioned difficulties in known chlorine dioxide gas generating compositions and provides a composition that can generate trace amounts of chlorine dioxide gas slowly and over a long period of time. In the present invention, a salt containing chlorine dioxide is oxidized to generate chlorine dioxide gas even in an alkaline region in the presence of an alkaline substance with oxidizing ability supported on a chlorinated solid powder, and the rate of generation is This is based on the knowledge that this is slow and persistent. That is, the gist of the present invention is to slowly generate chlorine dioxide gas, which is characterized by consisting of an alkaline solid substance with a pH of 8 or higher, a chlorite or stabilized chlorine dioxide supported or contained therein, and an alkaline oxidizing agent. In the composition. Salts containing chlorine dioxide are chlorites of alkali or alkaline earth metals, e.g.
NaClO ₂ , KClO ₂ , LiClO ₂ , Ca(ClO ₂ ) ₂ , Ba
(ClO ₂ ) ₂ , Mg(ClO ₂ ) _{2 ,} etc., but a particularly economical and practical substance is sodium chlorite.
Known stabilized chlorine dioxide can also be used in place of chlorite. These substances produce chlorite (HClO ₂ ) in an acidic system with a pH of 6 or less in the presence of water, and this substance produces chlorine dioxide through a self-oxidation reaction, so chlorite is Lowering the pH of the composition containing chlorine to below 6 will temporarily generate a large amount of chlorine dioxide gas. This is a drawback of known chlorine dioxide-containing compositions. However, in the composition of the present invention, the oxidation of chlorite is slow and sustained in the presence of an alkaline substance with oxidizing ability in the alkaline range of pH 8 to 12, where chlorite is originally stable. can be made to do so. In the present invention, various aminosilicates, magnesium silicate, calcium silicate, powdered silica gel, etc. are used as the alkaline solid substance. These are preferably in powder form.
These may be either naturally occurring or synthetic, and a mixture of natural and synthetic may also be used. These solid powders have a PH
It is preferable that the pH is within the range of 8-12, but if the pH is below 8, sodium carbonate, sodium bicarbonate,
It can be used by adding an alkaline substance such as calcium carbonate to adjust the pH to the above alkaline range. Other properties required for alkaline solid powders include having appropriate hygroscopicity;
It has excellent processability such as granulation and solidification. Examples of alkaline substances that can oxidize chlorite ions in alkaline regions include oxides or hydroxides of iron, chromium, manganese, lead, copper, silver, mercury, bismuth, selenium, and alkali or alkaline earth metals. Examples include solid or powdered substances such as oxyhalogen salts, permanganates, and dichromates. These substances must be alkaline with a pH of 7 or higher. These alkaline substances may originally be contained in alkaline solid powders, but for solid powders that contain a small amount of these substances or do not contain these substances at all, an appropriate amount of oxidation may be necessary. It is necessary to add an alkaline substance with the ability. In the composition of the present invention, the required amount of these alkaline substances varies depending on the rate of chlorine dioxide gas generation required for the composition, but as a general guide, it is Approximately 0.1% to 20%,
In particular, 1% to 10% is preferred. Further, an amount of alkaline oxidizing agent exceeding the theoretical oxidation equivalent required to oxidize the chlorite contained in the composition to generate chlorine dioxide gas is unnecessary. In producing the composition of the present invention, chlorite is adsorbed onto an alkaline solid powder containing an alkaline substance capable of oxidizing chlorite ions as described above. As the chlorite, an alkali or alkaline earth metal salt of chlorite is used.
Generally, sodium chlorite is used because it is the cheapest and most easily available. A powder or an aqueous solution containing the chlorite can be used, but an aqueous solution of the chlorite is preferable in order to uniformly mix it with the alkaline solid powder. An alkali substance such as NaCO ₃ or NaHCO ₃ may be added as a stabilizer to this aqueous solution. As the aqueous solution of chlorite, an industrially produced solution can be used as it is or one diluted with water as appropriate. It is of course possible to use a known stabilized chlorine dioxide aqueous solution in place of the chlorite aqueous solution. A stabilized aqueous chlorine dioxide solution can be produced by absorbing chlorine-free chlorine dioxide gas into an aqueous solution of an alkaline peroxygen compound, such as sodium percarbonate, magnesium peroxide, calcium peroxide, sodium peroxide, and the like. The above chlorite aqueous solution or stabilized chlorine dioxide aqueous solution is uniformly mixed with the above alkaline solid powder by a known method. This operation can be carried out, for example, by gradually adsorbing or spraying the aqueous solution while stirring the solid powder in a powder mixer. This mixture is then preferably dried to obtain a chlorine dioxide-containing composition of the invention that is substantially water-free. This drying can be carried out by any known suitable method, but it is preferably carried out at a temperature of 80° C. or lower under normal pressure or reduced pressure. If a large amount of water remains, the stability of the composition will be poor. Although the specific manufacturing process of the composition of the present invention is described below, the manufacturing process of the composition of the present invention is not limited thereto. For example, chlorite or stabilized chlorine dioxide is adsorbed onto an alkaline solid substance The alkaline oxidizing agent may be supported or adsorbed on the alkaline solid material, or the alkaline solid material may be combined with a composition in which chlorite or stabilized chlorine dioxide is supported or adsorbed on the alkaline solid material, and an alkaline solid material may be supported or adsorbed with the alkaline oxidizing agent. The composition of the invention can also be obtained by mixing with solid substances. The composition of the present invention, unlike known compositions, generates chlorine dioxide gas slowly and continuously, and therefore can be used as a deodorizing or deodorizing agent, a preservative, a disinfectant, a fungicide, a disinfectant, etc. It can be suitably used. During use, moderate moisture in the air helps generate chlorine dioxide. Next, specific implementation methods and effects of the present invention will be explained with reference to Examples. All percentages or proportions used in the examples represent weight percentages or parts by weight. Example 1 Natural magnesium silicate with the following composition was used as solid powder raw material. As SiO ₂ 41.0% As Al ₂ O ₃ 15.2 As MgO 18.8 As Fe ₂ O ₃ 12.1 As CaO 6.9 As Na ₂ O 0.3 As K ₂ O 0.7 Ignition loss 5.0 Particle size Passage below 200 mesh PH 10-10.8 100g of this material Inside, iron peroxide (Fe ₃ O ₄ )7.3
Contains g. While stirring this substance, the pH
24 parts of a 25% aqueous solution of sodium chlorite (No. 11.5) was sprayed on 100 parts of the above substance, mixed uniformly, and adsorbed. Next, this mixture is heated to 600mm below 80℃.
It was dried under reduced pressure of Hg for 6 hours to obtain a powdery anhydride. This dried product contained 32,000 PPm of chlorine dioxide and had a pH of 9.8. Pack 10 g of this substance in breathable paper, place it in an Erlenmeyer flask with a capacity of 300 c.c., and measure the state of chlorine dioxide gas generation and PH under conditions of a temperature of 6 ° C. and a humidity of 20%. I got the following results.

[Table] Example 2 Synthetic calcium silicate with pH 9.0 and 300 mesh or less was used as the alkaline solid powder. This substance is purified by metathesizing calcium metasilicate with calcium chloride. To 100 parts of this material, homogeneous mixtures A, B, C and D were prepared by adding the following metal oxide powders.

[Table] 100 parts of each of the above mixtures and 40 parts of a stabilized chlorine dioxide aqueous solution containing 5% ClO ₂ were kneaded uniformly, and the temperature was 60°C.
It was dried for 3 hours at a temperature of 720 mmHg. The dried material was ground in a mortar to obtain a powder of less than 300 mesh.
The ClO ₂ content and PH of these powders were as follows.

[Table] The state of ClO ₂ generation was observed for each of the above powders under the same conditions as in Example 1, and the following results were obtained.

[Table] Comparative Example 1 To 100 parts of the synthetic calcium silicate used in Example 2, 20 parts of a sodium chlorite aqueous solution having a pH of 11.5 and a concentration of 25% was sprayed and mixed uniformly. mixture
It was dried for 6 hours at a temperature of 80° C. or lower and under a reduced pressure of 600 mmHg, and the dried material was ground into 300 mesh or less. of this powder
The ClO ₂ content was 31,300PPm and the pH was 9.2. When 10 g of this powder was placed in an Erlenmeyer flask and placed in a refrigerator at a temperature of 8° C. and a humidity of 20% to observe the generation of chlorine dioxide, no generation of chlorine dioxide was observed even after 20 days had elapsed. After 20 days, the ClO ₂ content and
PH did not change. Example 3 For 1 part of the powder prepared in Comparative Example 1,
Two parts of natural zeolite having the following composition were mixed uniformly. As SiO ₂ 69.0 As Al ₂ O ₃ 10.0 As MgO 10.5 As Fe ₂ O ₃ 6.1 As CaO 2.0 As PbO 1.1 As K ₂ O 1.0 Ignition loss 0.7 100.0 PH 8.3, particle size 150 mesh or less Add 10 g of this substance to an Erlenmeyer flask When the sample was placed in a refrigerator at a temperature of 8°C and a humidity of 20%, the state of chlorine dioxide generation was observed, and the following results were obtained.

[Table] Example 4 Same synthetic calcium silicate used in Example 2
Homogeneous mixtures E, F, and G were prepared by adding the following oxidizing agents to 100 parts.

[Table] Composition prepared in Comparative Example 1 (ClO ₂ content
31300PPm, PH9.2 powder) and 1 part of each of the above mixtures E, F, and G were uniformly mixed. 6 g of the three types of compositions obtained were packaged in air-permeable paper, and the volume was It was placed in a 300 c.c. Erlenmeyer flask, and the state of chlorine dioxide gas generation was measured in an atmosphere with a temperature of 15°C and a humidity of about 60%, and the following results were obtained.

[Table] Comparative Example 2 For 10 parts of the powder prepared in Comparative Example 1,
Eight parts of a powder product made by uniformly mixing synthetic calcium silicate powder and ferric chloride powder with a purity of 99.9% at a ratio of 1:1 was mixed. The chlorine dioxide content of this mixture was 12,000 PPm and the pH was 5.5. Regarding this powder mixture, the state of generation of chlorine dioxide was observed under the same conditions as in Example 3.

[Table] As is clear from the above examples, the composition of the present invention in which chlorite or stabilized chlorine dioxide and an alkaline oxidizing agent are supported or adsorbed on an alkaline solid substance slowly and over a relatively long period of time. Generates chlorine dioxide stably over time. On the other hand, as seen in Comparative Example 1, no generation of chlorine dioxide was detected in the composition in which no alkaline oxidizing agent was present.
Furthermore, as shown in Comparative Example 2, in the composition containing an acidic substance, a large amount of chlorine dioxide gas is generated in a very short period of time, and it is difficult to maintain the slow generation of chlorine dioxide for a long period of time. Can not.

Claims (1)

[Claims] 1. A composition that slowly generates chlorine dioxide gas, comprising an alkaline solid substance with a pH of 8 or higher, a chlorite supported or contained therein, or stabilized chlorine dioxide, and an alkaline oxidizing agent.