Polyorganosiloxane emulsions with large particle size and process for their preparation

A process for preparing storage-stable, aqueous polyorganosiloxane emulsions comprising

• (A) at least one polyorganosiloxane of the general formula
• where
• R1 may be identical or different and is a hydrogen atom or a monovalent, substituted or unsubstituted hydrocarbon radical,
• R2 may be identical or different and is a monovalent, substituted or unsubstituted hydrocarbon radical having 1 to 30 carbon atoms or a hydrogen atom,
• a is 0, 1, 2 or 3,
• b is 0, 1, 2 or 3,
• with the proviso that the sum total of a+b is ≤3,
• (B) at least one alkyl polyglycoside of the general formula
• where
• A is a linear or branched, saturated or unsaturated alkyl radical having 8 to 24 carbon atoms,
• G is a glycoside radical and
• m is the degree of glycosidation and is an integer of on average 1 to 5,
• (C) water,
• optionally
• (D) further emulsifiers that are different from the alkyl polyglycosides (B),
• optionally
• (E) thickeners
• and optionally
• (F) further additives that are usually present in polyorganosiloxane emulsions,
• characterized in that
• (v) a total of 1.5 to 4.5 parts of alkyl polyglycoside (B) are present per 100 parts of polyorganosiloxane (A),
• (vi) a total of 0 to 3 parts of further emulsifiers (D) are present per 100 parts of polyorganosiloxane (A),
• (vii) the sum total of the parts of alkyl polyglycoside (B) and further emulsifiers (D) is ≤4.5 per 100 parts of polyorganosiloxane (A)
• and
• (viii) the process comprises the following steps
• (5) preparation of an emulsifier-water mixture comprising
• at least one alkyl polyglycoside (B) and water (C) and optionally further emulsifiers (D), optionally thickeners (E) and optionally further additives (F) preparation of a preliminary emulsion by addition of
• (6)
• at least one polyorganosiloxane (A) to the emulsifier-water mixture, with the proviso that the preliminary emulsion is prepared under the action of low shear forces using stirring devices with maximum peripheral speeds of 4.5 m/s,
• optionally
• (7) dilution of the preliminary emulsion by addition of
• further water (C)
• and optionally
• (8) addition of further additives (F),
• where the process yields polyorganosiloxane emulsions having a particle size D(50) of 1 μm to 50 μm, based on the D(50) value of the volume distribution measured in accordance with the principle of Fraunhofer diffraction (according to ISO 13320),
• and in that polydimethylsiloxanes having a viscosity of 10 000 mPa·s to 3 000 000 mPa's (determined at 25° C. in accordance with DIN 53019) are used as polyorganosiloxanes (A).

Storage-stable, aqueous polyorganosiloxane emulsions comprising

• (A) at least one polyorganosiloxane of the general formula
• where
• R1 may be identical or different and is a hydrogen atom or a monovalent, substituted or unsubstituted hydrocarbon radical,
• R2 may be identical or different and is a monovalent, substituted or unsubstituted hydrocarbon radical having 1 to 30 carbon atoms or a hydrogen atom,
• a is 0, 1, 2 or 3,
• b is 0, 1, 2 or 3,
• with the proviso that the sum total of a+b is ≤3,
• (B) at least one alkyl polyglycoside of the general formula
• where
• A is a linear or branched, saturated or unsaturated alkyl radical having 8 to 24 carbon atoms,
• G is a glycoside radical and
• m is the degree of glycosidation and is an integer of on average 1 to 5,
• (C) water,
• optionally
• (D) further emulsifiers that are different from the alkyl polyglycosides (B),
• optionally
• (E) thickeners
• and optionally
• (F) further additives that are usually present in polyorganosiloxane emulsions,
• characterized in that
• (i) a total of 1.5 to 4.5 parts of alkyl polyglycoside (B) are present per 100 parts of polyorganosiloxane (A),
• (ii) a total of 0 to 3 parts of further emulsifiers (D) are present per 100 parts of polyorganosiloxane (A),
• (iii) the sum total of the parts of alkyl polyglycoside (B) and further emulsifiers (D) is ≤4.5 per 100 parts of polyorganosiloxane (A)
• and
• (iv) the emulsions are produced by a process comprising the steps
• (1) preparation of an emulsifier-water mixture comprising at least one alkyl polyglycoside (B) and water (C) and optionally further emulsifiers (D), optionally thickeners (E) and optionally further additives (F),
• (2) preparation of a preliminary emulsion by addition of at least one polyorganosiloxane (A) to the emulsifier-water mixture, with the proviso that the preliminary emulsion is prepared under the action of low shear forces using stirring devices with maximum peripheral speeds of 4.5 m/s,
• optionally
• (3) dilution of the preliminary emulsion by addition of further water (C)
• and optionally
• (4) addition of further additives (F),
• with the proviso that the polyorganosiloxane emulsions have a particle size D(50) of 1 μm to 50 μm, based on the D(50) value of the volume distribution measured in accordance with the principle of Fraunhofer diffraction (according to ISO 13320),
• and in that polydimethylsiloxanes having a viscosity of 10 000 mPa's to 3 000 000 mPa's (determined at 25° C. in accordance with DIN 53019) are used as polyorganosiloxanes (A).