Surface treated silicas
View Patent ↗Disclosed is a silica substrate treated with a polysiloxane, and an organosilane, wherein the organosilane is described by the formula: RSi(R′) x (OR″) 3-x ; wherein R is a long-chain hydrocarbon group having between about 8 to about 30 carbon atoms, which may also contain organofunctional groups such as vinyl, methacryl, amino, sulfur, and epoxy groups; R′ and R″ are independently selected from a methyl and ethyl group; and X is either 0 or 1. The optimal use for the treated silica substrate is as a rheology modifier in epoxy polymer materials, however, the silica substrate could also be used in other chemical compositions such as polyurethanes, polyesters, silicones, and hydrocarbon oils.
1. A precipitated silica substrate treated with a polysiloxane, and an organosilane, wherein the organosilane is described by the formula:
RSi(R′) x (OR″) 3-x (II)
wherein R is a long-chain hydrocarbon group having between about 8 to about 30 carbon atoms, and optionally contains organofunctional groups selected from the group consisting of vinyl, methacryl, amino, sulfur, and epoxy groups;
R′ and R″ are independently selected from the group consisting of a methyl and an ethyl; and
X is either 0 or 1;
wherein said precipitated silica substrate is treated first with said polysiloxane and subsequently with said organosilane;
wherein said precipitated silica substrate imparts a shear thinning index measured as STI=V 20 Pa /V 200 Pa from about 1.2 to 100 to a polymer composition.
2. The precipitated silica substrate of claim 1 , wherein the silica has a BET specific surface area of from about 50 to about 150 m 2 /g.
3. The precipitated silica substrate of claim 1 , wherein the silica has an average particle size of from about 2 to about 10 microns.
4. The precipitated silica substrate of claim 1 , wherein the organosilane is a hexadecyltrimethoxysilane.
5. The precipitated silica substrate of claim 1 , wherein the polysiloxane has the formula:
wherein n is an integer greater than 1, preferably between about 30 to about 100; X is selected from the group consisting of a hydrogen atom and an R′ group; R and R′ are independently selected organic groups, with from abut 1 to about 20 carbon atoms; and Y and Z are silicon-containing terminating end groups.
6. The precipitated silica substrate of claim 1 , wherein Y is —OSi(CH 3 ) 3 and Z is —Si(CH 3 ) 3 .
7. The precipitated silica substrate of claim 1 , wherein the polysiloxane is polydimethylsiloxane.
8. A polymer composition comprising the precipitated silica substrate of claim 1 .
9. The polymer composition according to claim 8 , further comprising a polymer selected from the group consisting of epoxy resin, polyurethanes, polyesters, silicones, hydrocarbon oils, and any mixtures thereof.
10. The precipitated silica substrate of claim 1 , wherein the silica substrate imparts a shear thinning index from about 1.4 to about 5 to said polymer composition.
11. The precipitated silica substrate of claim 10 , wherein the silica has a BET specific surface area of from about 50 to about 150 m 2 /g.
12. The precipitated silica substrate of claim 10 , wherein the silica has an average particle size of from about 2 to about 10 microns.
13. The precipitated silica substrate of claim 10 , wherein the organosilane is a hexadecyltrimethoxysilane.
14. The precipitated silica substrate of claim 10 , wherein the polysiloxane has the formula:
wherein n is an integer greater than 1, preferably between about 30 to about 100; X is selected from the group consisting of a hydrogen atom and an R′ group; R and R′ are independently selected organic groups, with from abut 1 to about 20 carbon atoms; and Y and Z are silicon-containing terminating end groups.
15. The precipitated silica substrate of claim 10 , wherein Y is —OSi(CH 3 ) 3 and Z is —Si(CH 3 ) 3 .
16. The precipitated silica substrate of claim 10 , wherein the polysiloxane is polydimethylsiloxane.
17. A polymer composition comprising the precipitated silica substrate of claim 10 .
18. The polymer composition according to claim 17 , further comprising a polymer selected from the group consisting of epoxy resin, polyurethanes, polyesters, silicones, hydrocarbon oils, and any mixtures thereof.