SU876645A1 - Method of purifying oligoethoxyloxanes - Google Patents

Description

(54) METHOD FOR CLEANING OLIGOETOXISYLOXANES

The invention relates to the chemistry of organosilicon compounds, namely to the purification method of oligoethoxysylsans of the general formula OC, H5 -Si-O- / fi, where n 2-7, which are used as a binding agent in precise casting processes. .-. A known method of purification of tetraetics sysilane by treating it with activated carbon fl. The closest to the proposed technical essence and the achieved result is the method of oAigoethoxysiloxanes purification from fine mechanical impurities by treating oligostoxysiloxanes with an aqueous solution of ammonium sulfide followed by separation of the resulting precipitate 2}. A disadvantage of the known method is that aqueous solutions cause the hydrolytic decomposition of oligoethoxysiloxanes, and the impurities of sulphides and fids in it are contaminated during the process of pouring methlischee products with sulfur, which is an undesirable admixture of metals in metals, and oligostoxysiloxes | receive with insufficient purity. Indicators of the purity of rygoztoxysiloxanes are chromaticity, determined by iodometric scale, and optical density, which by this method have high values, i.e. 8 and 2.5. Accordingly. The purpose of the invention is to increase the purity of the target product. This goal is achieved by the fact that in the method of purification of oligostoxysiloxanes of the formula I from finely dispersed, mechanical impurities, an organofactory surfactant of the general formula is used as a chemical reagent

caij-CH j-CH j-0 - cHj-M

where rc-x (c); X is hydrogen or

fluorine,

K 2 or 3, tons 6-9 and 6-11,.

in the amount of 0.001-0.01% by weight of oligoethoxysiloxane in an environment of absolute ethyl alcohol, followed by separation of the obtained precipitate.

The mechanism of action of surfactants of the formula consists in aggregating finely dispersed mechanical impurities into large conglomerates, the sedimentation and separation of which is faster and easier than in the known methods.

The use of surfactants of formula 1 as a processing chemical reagent allows to reduce color by 4 times and density by 2 times, thereby increasing the purity of the target product from fine mechanical impurities.

Example 1. A solution is prepared by dissolving 1 g of poly-5-vinyl-3-methyl-N- (perfluorovaleroyl-amide-M-ethoxymethyl) -pyridinium chloride () in 20 ml of absolutized ethanol. 100 ml of crude ethyl silicate-40, (p. 7), color 7 according to the color iodometric scale, are placed into the measuring cylinder, 0.03 ml of the prepared surfactant solution is added to it, which yields 0.001% surfactant ) with respect to ethyl silicate -40 (ETS-40), mix the contents of the cylinder for 5-10 minutes with a glass bottle, then transfer the resulting solution to centrifugation tubes. The solution is centrifuged in a laboratory centrifuge with a separation spindle of 2000 for 1 minute, then the liquid is separated from the residue by decantation. As a result of the purification, a pro ethyl ethylsilshsat-40 is obtained, having a color of 2 in terms of chromaticity (the color of the product depends on the number of mechanical materials). .

Example 2. The initial ETS-40 was cleaned with a color on a color scale equal to 7, similarly to Example 2, but for cleaning use solution A in an amount of 0.2 ml, corresponding to the surfactant content in ETS-40

(CH-CHi) "- (c H-CHi) ii

iB-m

SKZ

SNS

0.01% wt.%. Received after cleaning ETS-40 has a color of 2 on a scale of color.

Example 3. Purification of initial ethyl silicate-40 with a color on a color scale equal to 7, as indicated in example 1. For cleaning use solution A in an amount of 0.1 ml, corresponding to the content of surfactant in ETS-40 0.005 wt.%. ETS-40 obtained after purification has a color of less than 2 on a color scale.

EXAMPLE 4 Solution B is prepared by dissolving 1 g of poly-5-vinyl3 methyl-N- (N-ethoxymethyl) -pyridinium-chloride perfluoroheptanoyl amide () in 20 ml of ethanol. Purification of the initial ETS-40, possessing a color on a color scale equal to 7, is carried out in analogy to example 1 by adding 0.02 ml of solution B, which corresponds to 0.001 wt.% Surfactant in ETS-40. After cleaning, the color of ETS-40 on a color scale corresponds to 2. Example 5. The source ETS-40 is cleaned with a color on a color scale of 7, similarly to 1, but solution B is used in cleaning in an amount of 0.2 ml corresponding to Surfactant in ETS-40 0.01 wt.%. Received after cleaning ETS40 has a color of 2 on a color scale.

Example 6. The initial ETS-40 was cleaned with a color on a color scale equal to 7, as indicated in example 1, but for cleaning use solution B in an amount of 0.1 ml, corresponding to the content of surfactant in ETS-40 0.005 wt.%. The ETS-40 obtained after cleaning has a color of less than 2 in the color scale.

Example 7. Purification of the initial ETS-32 (n-2) with the initial optical density of solution 1.8 is carried out in the same way as in Example 1, but for cleaning use solution A in an amount of 0.1 ml, corresponding to the surfactant content in ETS-32 0.005 weight. % Received after cleaning ETS-32 has an optical density of 0.9.

The table presents the comparative data on the purity of products purified by the known and proposed method.

Claims (1)

Claim The method of purification of oligoethoxysiloxanes of the formula / OS ₂ n ₅ \ And ¹ '° \ ^OS aH ₅ / _{and t} Ry ~ C ** 0 ύκ where R _f - x (CFj, CF _a ) _k ', x is hydrogen or fluorine, k = 2 or 3, w = 6 to 9 and η = 6 - 11, in an amount of 0.001- 0.01% of the weight of oligoethoxysiloxane and absolute ethyl alcohol is taken as a solvent.