High-viscosity aqueous emulsions of functional alkoxysilanes, condensed oligomers thereof, organopolysiloxanes, their preparation and use for surface treatment of inorganic materials
View Patent ↗High-viscosity aqueous emulsions of functional alkoxysilanes, condensed oligomers thereof, organopolysiloxanes, their preparation and use for the surface treatment of inorganic materials High-viscosity aqueous oil-in-water emulsion which comprises from 50 to 90% by weight, based on the total weight of the emulsion, of functional alkoxysilanes and/or condensed oligomers thereof and/or organoalkoxysiloxanes, at least one emulsifier and water and has a pH of from 5 to 9 and a mean droplet size of the disperse phase of less than 5 μm, wherein the width of the droplet size distribution, expressed as the span (see formula (I)), is >1.5, preferably from 3 to 8. The preparation of the emulsions having the desired droplet size distribution is carried out in apparatuses having at least one pressure stage at a pressure of from 2 to 15 MPa. The emulsion can be used for hydrophobicizing porous mineral building materials. D 90 - D 10 D 50 ( I )
1. A high-viscosity aqueous oil-in-water emulsion which comprises from 50 to 90% by weight, based on the total weight of the emulsion, of functional alkoxysilanes and/or condensed oligomers thereof and/or organoalkoxysiloxanes, at least one emulsifier and water and has a pH of from 5 to 9 and a mean droplet size of the disperse phase of less than 5 μm, wherein the width of the droplet size distribution, expressed as the span
D
90
-
D
10
D
50
,
is
>
3.
2. The high-viscosity emulsion as claimed in claim 1 , wherein the span is from 3 to 8.
3. The high-viscosity emulsion as claimed in claim 1 , wherein the functional alkoxysilanes are selected from among alkoxysilanes or mixtures of the formulae
R 1 —Si(OR 2 ) 3 ,(R 1 ) 2 —Si(OR 2 ) 2 ,
where the radicals R 1 are identical or different and are each C 3 -C 18 -alkyl, halogen- or amino-substituted C 3 -C 18 -alkyl, vinyl, mercaptoalkyl, methacryloxyalkyl, acryloxyalkyl, alkylaminoalkyl, dialkylaminoalkyl, diethyleneaminoalkyl, triethyleneaminoalkyl, glycidyloxyalkyl, bisalkoxysilylalkyl, monosulfane or polysulfane and R 2 is an alkyl radical having from 1 to 6 carbon atoms.
4. The high-viscosity emulsion as claimed in claim 1 , wherein the condensed oligomers of the functional alkoxysilanes are selected from among alkoxysilanes or mixtures of the formula
where R 1 is C 3 -C 18 -alkyl, halogen- or amino-substituted C 3 -C 18 -alkyl, vinyl, mercaptoalkyl, methacryloxyalkyl, acryloxyalkyl, alkylaminoalkyl, dialkylaminoalkyl, diethyleneaminoalkyl, triethyleneaminoalkyl, glycidyloxyalkyl, bisalkoxysilylalkyl, monosulfane or polysulfane, the groups R 2 are identical or different and are each a hydrogen atom or an alkyl radical having from 1 to 6 carbon atoms, and n determines the degree of oligomerization and has a value of from 2 to 40.
5. The high-viscosity emulsion as claimed in claim 1 , wherein the organoalkoxysiloxanes are selected from among organoalkoxysiloxanes or mixtures of the formula
where m and n are identical or different and are each from 0 to 20, with the proviso that (n+m)>2, R and R 2 are identical or different and are each hydrogen, C 1 -C 18 -alkyl, halogen- or amino-substituted C 1 -C 18 -alkyl, phenyl, vinyl, mercaptoalkyl, methacryloxyalkyl, acryloxyalkyl, alkylaminoalkyl, dialkylaminoalkyl, diethyleneaminoalkyl, triethyleneaminoalkyl, glycidyloxyalkyl, bisalkoxysilylalkyl, monosulfane or polysulfane, the groups R 1 are identical or different and are each a hydrogen atom or an alkyl radical having from 1 to 6 carbon atoms.
6. The high-viscosity aqueous emulsion as claimed in claim 1 , wherein the at least one emulsifier is selected from among alkylsulfates having a C 8 -C 18 -alkyl radical, alkyl ether sulfates and alkaryl ether sulfates having a C 8 -C 18 -alkyl radical as hydrophobic radical and from 1 to 40 ethylene oxide (EO) or propylene oxide (PO) units, alkylsulfonates having a C 8 -C 18 -alkyl radical, alkarylsulfonates having a C 8 -C 18 -alkyl radical, monoesters of sulfosuccinic acid with monohydric alcohols or alkylphenols having from 5 to 15 carbon atoms, alkali metal and ammonium salts of carboxylic acids having from 8 to 20 carbon atoms in the alkyl, aryl, alkaryl or aralkyl radical, alkylphosphates and alkarylphosphates having from 8 to 20 carbon atoms in the organic radical, alkyl ether phosphates or alkaryl ether phosphates having from 8 to 20 carbon atoms in the alkyl or alkaryl radical and from 1 to 40 EO units, alkyl polyglycol ethers and alkaryl polyglycol ethers having from 8 to 40 EO units and from 8 to 20 carbon atoms in the alkyl or aryl radicals, ethylene oxide-propylene oxide (EO-PO) block copolymers having from 8 to 40 EO and PO units, addition products of alkylamines having C 8 -C 22 -alkyl radicals with ethylene oxide or propylene oxide, alkyl polyglycosides having linear or branched, saturated or unsaturated C 8 -C 24 -alkyl radicals and oligoglycoside radicals having from 1 to 10 hexose or pentose units, silicon-functional surfactants or mixtures of these emulsifiers.
7. The high-viscosity aqueous emulsion as claimed in claim 6 , wherein the at least one emulsifier is present in an amount of from 0.01 to 5% by weight, based on the total weight of the emulsion.
8. The high-viscosity aqueous emulsion as claimed in claim 1 which further comprises customary auxiliaries selected from among inorganic or organic acids, buffer substances, fungicides, bactericides, algaecides, microbicides, fragrances, corrosion inhibitors, preservatives, rheological auxiliaries, water repellents, catalysts.
9. A process for preparing high-viscosity aqueous oil-in-water emulsions comprising functional alkoxysilanes and/or condensed oligomers thereof and/or organoalkoxysiloxanes, at least one emulsifier and water comprising (i) premixing the constituents and (ii) emulsifying the mixture in a high-pressure homogenizer having at least one pressure stage and a pressure of from 2 to 15 MPa, so that the mean droplet size is less than 5 μm, wherein the width of the droplet size distribution, expressed as the span
D
90
-
D
10
D
50
,
is
>
3.
10. The process as claimed in claim 9 , wherein the pressure in at least one pressure stage is from 4 to 8 MPa.
11. The process as claimed in claim 9 , wherein a pre-emulsifying (iii) is additionally carried out in the high-pressure homogenizer having at least one pressure stage under a pressure of from 10 to 70 MPa after said premixing (i) and before said emulsifying (ii).
12. The process as claimed in claim 9 , wherein said emulsifying (ii) is carried out using 2 pressure stages having different pressures.
13. The process as claimed in claim 9 , wherein the emulsion is cooled on leaving the high-pressure homogenizer.
14. A high-viscosity aqueous oil-in-water emulsion produced by the process of claim 9 .
15. A process for hydrophobicizing a porous mineral building material comprising applying the emulsion of claim 1 to said porous mineral building material.
16. The high-viscosity emulsion as claimed in claim 2 , wherein the span is from 4 to 7.
17. The high-viscosity emulsion as claimed in claim 3 , wherein R 2 is an alkyl radical having 1 or 2 carbon atoms.
18. The high-viscosity emulsion as claimed in claim 4 , wherein the groups R 2 are identical or different and are each a hydrogen atom or an alkyl radical having 1 or 2 carbon atoms.
19. The high-viscosity emulsion as claimed in claim 5 , wherein the groups R 1 are identical or different and are each a hydrogen atom or an alkyl radical having 1 or 2 carbon atoms.
20. A process for preparing high-viscosity aqueous oil-in-water emulsions comprising functional alkoxysilanes and/or condensed oligomers thereof and/or organoalkoxy-siloxanes, at least one emulsifier and water comprising (i) premixing the constituents and (ii) emulsifying the mixture in a high-pressure homogenizer having at least one pressure stage and a pressure of from 4 to 8 MPa, so that the mean droplet size is less than 5 μm, wherein the width of the droplet size distribution, expressed as the span
D
90
-
D
10
D
50
,
is
>
1.5
.
21. The process as claimed in claim 11 , wherein the pressure is from 20 to 40 MPa.
22. The process as claimed in claim 15 , wherein said applying includes dipping, spraying, blade coating, brush coating, spatula coating, and combinations thereof.
23. The process as claimed in claim 15 , wherein said porous mineral building material includes concrete, limestone, lime-sand brick, and clay brick.
24. The process as claimed in claim 20 , wherein the pressure in at least one pressure stage is from 5 to 6 MPa.
25. A process for preparing high-viscosity aqueous oil-in-water emulsions comprising functional alkoxysilanes and/or condensed oligomers thereof and/or organoalkoxy-siloxanes, at least one emulsifier and water comprising (i) premixing the constituents and (ii) emulsifying the mixture in a high-pressure homogenizer having at least one pressure stage and a pressure of from 2 to 15 MPa, so that the mean droplet size is less than 5 μm, wherein the width of the droplet size distribution, expressed as the span
D
90
-
D
10
D
50
,
is
>
1.5
,
wherein the emulsion is cooled on leaving the high-pressure homogenizer.
26. A process for preparing high-viscosity aqueous oil-in-water emulsions comprising functional alkoxysilanes and/or condensed oligomers thereof and/or organoalkoxy-siloxanes, at least one emulsifier and water comprising (i) premixing the constituents and (ii) emulsifying the mixture in a high-pressure homogenizer having at least one pressure stage and a pressure of from 2 to 15 MPa, so that the mean droplet size is less than 5 μm, wherein the width of the droplet size distribution, expressed as the span
D
90
-
D
10
D
50
,
is
>
1.5
,
wherein a pre-emulsifying (iii) is additionally carried out in the high-pressure homogenizer having at least one pressure stage under a pressure of from 20 to 40 MPa after said premixing (i) and before said emulsifying (ii).