DE2013763A1 - Powders contng hydrogen peroxide andsilica - Google Patents

Abstract

Powders contain >=9 wt. %, pref. 10-35 wt. % of finely-divided, pure, hydrophobic silicic acid. Powders are used e.g. as bleaches.

Description

Powdered H2O2 and SiO2 persistent products "Subject matter of the invention are powdery products containing H202 and SiO2 that have a variable, in particular also have a high content of H202 as well as the manufacture of these products.

It is known that hydrogen peroxide is associated with numerous inorganic and organic compounds form addition products. The stability of these connections is quite different and only a few perhydrates are used technically. Well-known and relatively stable compounds are, for example, melamine perhydrate, Carbamide peroxide and sodium perborate (NaBO2 H202). The active oxygen content of this However, connections is less than 18% in all cases.

In addition, there are already addition compounds of H 2 O 2 on silica has been manufactured. These compounds are not very stable or have only a low degree of stability Active oxygen content. Products containing silica with a high The proportion of H202 was previously only known in paste form.

It has now been found that pulverulent viO2-containing products can be used can produce with a variable, especially a high content of H202, using the procedure described below.

This is characterized in that finely divided pure water-repellent ones are used Silicic acid treated with an H202-L8sullg at temperatures below 500, whereby the Percentage of hydrophobized silica, based on the total product, at least 9, preferably 10-35% by weight.

The production of finely divided KieselsMure takes place according to known methods Methods such as precipitation from alkali silicate solutions by acidic substances or by Decomposition of silicon tetrachloride with water at high temperatures (pyrogenic Silica). It is essential that substances that cause a decomposition of hydrogen peroxide cause are largely removed. It is therefore expedient to distribute them Silicas used, their proportions of metal oxides, especially iron oxide, less than 0.003 fi, preferably pyrogenic silica is used as a starting product because it is particularly pure and has a low bulk weight having. The diameter of the particles is preferably in the range of "10-4 ° The surface-coated silica is hydrophobicized according to a method known per se Methods that are not the subject of the present invention. kls water repellant In particular, chlorosilanes such as (CH3) 2SiCl2 or fatty alcohols are used with 8-26 carbon atoms. In detail, there are such water repellant processes in US patent step 2,657,149 and in Austrian patent 239 194 described.

The concentration of the aqueous H 2 O 2 solution can depending on the desired End product fluctuate within wide limits.

Preferably, H202 solutions are used whose concentration is at least 20% by weight, in particular 50 to 70% by weight, was. However, there are also higher concentrations up to practically 100% H202 possible.-Treatment of the finely divided hydrophobized Silicic acid with H202 solution can be done in different ways. It is essential that that a very intensive mixing of the components, their specific weight differs significantly from each other, is guaranteed. The components can be mixed in any order. However, the aim is to have one Kind of droplet formation takes place so that the liquid phase separates from the solid phase can be wrapped. Good mixing is achieved, for example, by means of vibration devices. Furthermore, the powdery products containing H2O2 and SiO2 can be made from the Components are produced in the fluidized bed process.

The treatment is expediently carried out at temperatures below 500e, preferably at 0 to 300C. If higher temperatures are used, noticeable results occur Losses of H202. In order to obtain a solid product it is necessary that the proportion of hydrophobized silica, based on the total product, is at least 9% by weight. The proportion of hydrophobized silica is preferably in the final product 10-35% by weight. It is of course possible to get an even bigger one Amount of hydrophobized silica to be used. However, then the proportion of In202 or active oxygen in the end product is always lower.

The powdery ones that can be produced by the process described above Products have good stability. If desired, the stability can still can be further improved if stabilizers known per se for H202, such as sodium stannate, monosodium phosphate, phenacetin, o "-oxyquinoline in small amounts from about 0.1 to 6%> preferably 1 to 5%, can be added. It is there Useful if the H2O2 solutions contain such additives from the outset.

The new powdery products containing H202 and SiO2 can find application for many technical purposes. You can use bleaching, in particular of oils, fats and products containing cellulose. Farther They can be used as an additive to cleaning agents and in cosmetic products Find.

The advantage of these products is in particular that you can use the Content of H? .02 can vary within wide limits and in any case solid products receives. In particular, however, it is possible to produce dry powders, their Active oxygen content is significantly above 18%. The products own about it in addition, good stability.

Example 1 700 parts by weight of hydrogen peroxide were added 1,000 parts by weight of finely divided hydrophobized silica, the particle size of which averaged about 25 mp, mixed intensively with the help of a vibrator. The silica was produced by a pyrogenic route and by treatment with (CH3) 2 SiCl2 has been hydrophobized. A powdery end product was obtained5-which Contained 3.8% active oxygen.

Example 2 Using the same procedure as in Example 1, 100 Weight of 70% strength hydrogen peroxide with 10 parts by weight by pyrogenic route Silica produced and hydrophobized with dimethylchlorosilane, the particle size of which averaged about -25 mµ, mixed intensively with the aid of a vibrator. The resulting powdery product contained 29% active oxygen and had a Bulk weight of about 365 g / l.

A plastic bottle was filled to 90 degrees with the powder thus obtained and stored for one month at room temperature (20 to 250C). The easily deformable one Plastic bottle showed no bloating. The original active oxygen content of the product was practically unchanged.

The same result was obtained when this was in a plastic bottle bottled product was stored at 450C for 30 days. On the other hand, one was closed 90% of the plastic bottle filled with carbamide peroxide inflated after a short time.

Example 3 A pyrogenic silica, the mean particle size was about 20 e, was in a known manner by treatment hydrophobized with eicosanol at 2000 in the vapor phase. 10 parts by weight of each hydrophobic silica were mixed with 100 parts of 30% hydrogen peroxide or 50 parts of 70% hydrogen peroxide mixed intensively. The resulting powdery Products contained 12.5% and 27% active oxygen, respectively.

Example 4 By acid precipitation, finely divided silica, which contained less than 0.003% metal cations, prepared and then - how described in example 3 - hydrophobized. Then the hydrophobized silica using a vibrator mixed with 70% hydrogen peroxide, taking 3 parts H202 per part by weight of silica were used. The hydrogen peroxide solution was stabilized by adding 5% MaH2PG4 H20. It became a solid powdery Behave product, the active oxygen content of which was about 27%.

Claims (6)

Claims 1) Products containing powdery H202 and 3102, labeled due to a content of at least 9% by weight of finely divided pure water-repellent Silica based on total weight. 2) Powdered products according to claim 1, characterized in that that the content of hydrophobized silica is 10-35% by weight, based on the total weight, amounts to. 3) Fulver-like products according to claim 1 and 2, characterized by a content of pyrogenically produced and then hydrophobized silica. 4) Process for the preparation of powdered H202 and S102 containing Products, characterized in that one finely divided pure hydrophobized silica treated with an H202 solution at temperatures below 50 ° C, whereby. the proportion of hydrophobized silica, based on the total product, is at least 9% by weight. 5) Method according to claim 4, characterized in that finely divided hydrophobized silica treated with an H202 solution, the proportion of hydrophobized silica is 10-35% by weight. 6) Method according to claim 4 and 5, characterized in that one pyrogenic and then hydrophobized silica with H202 solution treated.