CS272846B1 - Silicon emulsion antifoaming agent - Google Patents

Abstract

The invention concerns the composition of a silicon emulsion anti-foaming agent, suitable for suppression of foam in aqueous systems. The silicon emulsion anti-foaming agent contains dimethyl polysiloxane, silicic oxide, glycerol monostearate, alkyl phenylpolyglycol ether and water, as well as an agent against micro-organisms.

Description

The invention relates to the composition of a silicone emulsion defoamer. This defoamer is particularly suitable for suppressing foam in aqueous systems.

Silicone antifoams typically contain a heat treated mixture of polydimethylsiloxane and a fine silica, a so-called silicone paste. This paste is emulsified with emulsifiers to achieve good dispersibility in the aqueous environment,

For emulsification, a mixture of two emulsifiers is often used, the appropriate composition of which ensures good emulsification of the hydrophobic phase in water.

If any component of the emulsion serves as a nutrient substrate for microorganisms, such as bacteria, yeasts, molds, the emulsion should be protected by the addition of preservatives. These are of a very diverse chemical composition, for example benzoic acid, sorbic acid, 4-hydroxybenzoic acid esters, chlorinated phenols, formaldehyde, sulfur dioxide; their common feature is that they stop the growth of microorganisms.

In emulsifying the silicone antifoam component, a mixture of a practically water-insoluble emulsifier which is a fatty acid ester of a multifunctional alcohol, e.g. for example, stearyl alcohol, oleyl alcohol, fatty acid ester ethoxylates with multifunctional alcohols containing still free hydroxy groups, for example sorbitol monostearate.

Silicone paste emulsification is a difficult problem. When the emulsions are stored, the oil phase sometimes separates at the top, in other cases the lower aqueous phase is separated, often the emulsion gradually solidifies to a non-flowing state. Particularly harmful is the separation of the oil phase, since it can no longer be mixed into the emulsion by simple mixing. For example, a defoamer with this defect cannot be used in dyeing textiles because it causes irreparable stains.

A silicone emulsion antifoam has now been found comprising 5 to 40 wt. % of polydimethylsiloxane, 0.1 to 3 wt.%, silica, 2 to 10 wt.% glycerol monostearate, 3 to 12 wt. alkylphenylpolyethylene glycol ether wherein the alkyl contains 7 to 20 carbons and the ethylene oxide group content is 45 to 75 wt. and the remainder to 100 wt. water.

If long-term stability against microorganisms is to be achieved, a preservative must be added.

The advantage of using alkylphenylpolyethylene glycol ether is its ability to strongly increase the viscosity of the aqueous phase, the liquid form and also the availability within certain concentration limits. Alkylphenylpolyethylene glycol ether has surprisingly proved to be a suitable emulsifying partner for both solid glycerol monostearate and silicone paste. The emulsions obtained are highly stable.

The stability of the prepared emulsions was evaluated by centrifugation, i.e. the emulsion was subjected to centrifugation replacing gravity for 6 months.

In the antifoams prepared according to the invention, no separation of the upper oil phase or separation of a larger amount of the lower aqueous phase was observed, and no emulsion solidification was observed upon storage.

Example 1

The glycerol monostearate used was a trademark of Polynol A Extra, nonylphenylpolyethylene glycol ether having an ethylene oxide group content of over 50% by weight was used as the alkylphenylpolyethylene glycol ether. Trademarks Slovafol X.

Preparation of "Siloxane A": A blend containing 96% trimethylsilyl terminated polydimethylsiloxane with a viscosity of 350 mPas / 20 ° C and 4% hydrophobized silica airgel was halogenated for 2 hours at 160 ° C.

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CS 272 846 B1 2

Preparation of Siloxane B: A blend containing 94.3% polydimethylsiloxane of the same type as Siloxane A and 5.7% non-hydrophobized silica airgel was processed as for Siloxan A.

Preparation of the emulsion: At a temperature below 80 ° C, the siloxane was homogenized with emulsifiers and water or a preservative, and at a temperature below 30 ° C, emulsification was carried out on a laboratory mixer.

The amounts of the individual components (in percent by weight) of the emulsion antifoams prepared are given in the following table:

Siloxan Glycerol- monostearate Alkylphenylpoly- ethylene glycol ether Sorbic acid Water 20 A 6 6 0.05 67.95 30 A 5 5 0.05 59.95 20 A 6 5 - 69 20 A 7 5 - 68 20 A 4,5 8.5 - 67 20 A 3 6.5 - 70.5 20 B 6 6 0.05 67.95

In the evaluation of the prepared emulsions by centrifugation test, no separated upper oil phase or lower aqueous phase was found. No emulsion solidification was found during storage.

EXAMPLE 2 20% Siloxane B, 4.5% low ethoxylated oleyl polyglycol ether (Brij 92), 1.6% high ethoxylated oleyl polyglycol ether (Brij 98) were used to prepare the emulsion. The rest is water.

The oil phase is separated from the emulsion.

Example 3

20% of Siloxane B, 4.7% of sorbitol monostearate (Span 60), 2.1% of polyglycol stearate (Myrj 52) were used.

The oil phase is separated from the emulsion.

Example 4

20% Siloxane B, 6.5% sorbitol monooleate (Span 80), 3.5% polyglycol sorbitol monooleate (Tween 80) were used.

The oil phase is separated from the emulsion.

Example 5

20% Siloxane A, 7% glycerol monostearate, 1.75% alkyl polyglycol ether (Emulan OG) were used.

The next day after preparation, the emulsion was completely solidified.

Claims (2)

Silicone emulsion defoamer, characterized in that it contains 5 to 40 wt. % polydimethylsiloxane, 0.1 to 3 wt. silica, 2 to 10% glycerol monostearate, 3 to 12 wt. alkylphenylpolyethylene glycol ether wherein the alkyl contains from 7 to 20 The carbon content of the ethylene oxide groups is 45 to 75% by weight, and the remainder to 100% by weight. water. 2. Defoamer according to claim 1, characterized in that it contains a preservative against microorganisms.