CS266032B1 - Antifoaming agent on base of polydimethylsiloxanes - Google Patents

Description

(57) The solution concerns an antifoam based on polydimethylsiloxanes. The essence is that the polydimethylsiloxane defoamer comprises 0.5 to 20 parts by weight of a paste consisting of a mixture of 90 to 99.5% by weight, polydimethylsiloxanes terminated with trimethylsilyl or hydroxy groups and 0.5 to 10% silica and 80 to 99.5 parts, parts of polypropylene oil. An advantage of the antifoam is that due to its chemical nature resulting from the presence of polypropylene oil (a hydrocarbon chain with protruding methyl groups) it is insoluble in water, which is desirable for the antifoam requirement.

The invention relates to a defoamer based on polydimethylsiloxanes. Defoamers are used in many sectors of the economy to solve unwanted foam problems arising from technological processes or to suppress foaming in the field of consumer chemistry, especially detergents. Of the wide range of antifoams, they differ in their composition and have a prominent position in silicone-based antifoams.

The basic component of these antifoams is a silicone paste prepared from polysiloxanes and a filler. Polysiloxanes are most often linear polydimethylsiloxanes terminated by trimethylsiloxy or hydroxy groups, but also branched siloxanes containing various silicon functional groups. Both of these groups are also used. The filler is a fine silica, usually prepared by a chemical reaction in the gas phase, i. aerogel SiO ₂ · It also contains hydroxy groups on its surface, which can be replaced by organosilicon groups.

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These antifoams are very effective. However, the disadvantage is that the silicone component is relatively expensive and does not always have suitable application properties. Therefore, it is often combined with other components that do not always have optimal parameters. They are, for example, mineral oils, organic acid esters, alcohols, polyalkylene glycols, surfactants, waxes.

The above-mentioned disadvantages do not have a polydimethylsiloxane defoamer, which consists in that it contains 0.5 to 20% by weight of a paste consisting of a mixture of 90 to 99.5% of polydimethylsiloxanes terminated with trimethylsilyl or hydroxy groups and 0.5 to 10% of silica and 80 to 10%. 99.5 wt. Parts of polypropylene oil.

Polypropylene oil is a mixture of branched olefins having a carbon number of 6 to 9, with an average content of 1.5 double bonds that is not at the end.

An advantage of the antifoam thus prepared is that due to its chemical nature resulting from the presence of polypropylene oil (a hydrocarbon chain with protruding methyl groups) it is insoluble in water, which is desirable for the antifoam requirement. Raw materials for the production of antifoams are commercially available chemicals.

The polydimethylsiloxane antifoam according to the invention can be used in powder detergents, industrial cleaners, detergents and in many other preparations, or even in industrial technological processes.

Polydimethylsiloxane defoamer is explained in more detail in the following examples:

Example 1 parts of paste prepared by heating 94.33% trimethylsiloxy terminated polydimethylsiloxanes with a viscosity of 350 mPa · s and 5.67% of SiO ₂ airgel at 160 ° C for 2 hours were mixed with 92 parts of polypropylene oil with a viscosity of 900 mPa · s and 2 parts of SiO ₂ and was mixed at 40 ° C for 0.5 h. The antifoam was obtained in the form of a liquid having a viscosity of 1,620 mPa · s, which can be incorporated into a powdered detergent composition with a predominantly nonionic surfactant by spraying with stirring. The foaming of the detergent is very effective already at a dose of 1% by weight of the detergent. The performance of antifoams was evaluated by an automatic washing machine test with foam height at the end of the selected washing cycle. The defoamer showed a foam height of 6 cm.

Example 2 parts of a paste prepared by heating a mixture of 98% polydimethylsiloxanes terminated with trimethylsiloxy viscosities of 350 mPa · s and 2% SiO ₂ airgel at 180 ° C for 4 hours were mixed with 91.5 parts of polypropylene oil of viscosity 900 mPa · s 2.5 parts of the airgel of SiO ₂ were stirred at 90 ° C for 0.5 hour. The antifoam had a viscosity of 1650 mPa · s. He showed a foam height of 8 cm in an automatic washing machine test.

EXAMPLE 3 parts paste prepared by heating a mixture of 97% hydroxy-terminated polydimethylsiloxane having a viscosity of 900 mPa.sa 3% SiO ₂ airgel ^at 180 ° C for 2 hours, was mixed with 91.5 parts polypropylene oil having a viscosity of 900 mPa.sa 2.5 aerogel parts

The SiO ₂ was stirred at 90 ° C for 0.5 h. The antifoam had a viscosity of 1750 mPa · s. He showed a foam height of 5 cm in an automatic washing machine test.

EXAMPLE 4 parts of a paste prepared by heating a mixture of 96% polydimethylsiloxane terminated with hydroxyl groups having a viscosity of 1230 mPa · s and 4% of SiO ₂ airgel to 160 ° C for 2 hours were mixed with 91.5 parts of polypropylene oil of 900 mPa · s 2. 5 parts of SiO ₂ airgel and stirred at 110 ° C for 1 hour. The antifoam had a viscosity of 1800 mPas. He showed a foam height of 1 cm in an automatic washing machine test.

Example 5 parts of a paste prepared by heating a mixture of 94.33% polydimethylsiloxane terminated with trimethylsiloxy having a viscosity of 350 mPa · s and 5.67% of SiO ₂ airgel at 160 ° C for 2 hours was mixed with 92 parts of polypropylene oil of 900 mPa · s. stirred at 20 ° C for 0.25 hours. The antifoam had a viscosity of 1040 mPa · s. He showed a foam height of 4 cm in an automatic washing machine test.

Example 6

The paste prepared by heating a mixture of 94.33% polydimethylsiloxane terminated with trimethylsilyl groups and 5.67% silica at 160 ° C for 2 hours was homogenized with water using polyvinyl alcohol as an emulsifier to an emulsion defoamer containing 30% paste. This antifoam showed a foam height of 20 cm in an automatic washing machine test.

The antifoams prepared according to the above examples had a good antifoam effect on the foaming bath in the automatic washing machine.

Claims (1)

SUBJECT OF THE INVENTION Polydimethylsiloxane defoamer, characterized in that it contains 0.5 to 20 parts by weight of a paste consisting of a mixture of 90 to 99.5% by weight, trimethylsilyl or hydroxy-terminated polydimethylsiloxane and 0.5 to 10% silica and 80 to 99, 5 parts by weight of polypropylene oil.