US 5,811,487 AGranted

Thickening silicones with elastomeric silicone polyethers

AssigneeDow Corning Corporation

InventorsWilliam James Schulz, Jr., Shizhong Zhang

Life of this patent

Estimating the term…

Loading patent…

Abstract

Low molecular weight siloxane fluids are thickened by silicone elastomers. The silicone elastomers are made by crosslinking reactions of .tbd.Si--H containing siloxanes and an unsaturated hydrocarbon such as an alpha, omega-diene, in the presence of a low molecular weight siloxane fluid. The .tbd.SiH siloxane is first partially reacted with a mono-alkenyl functionalized polyether. It is then crosslinked by the alpha, omega-diene, in the presence of the low molecular weight siloxane fluid. An elastomer, i.e. gel, with polyether groups is produced. The elastomer can be swollen with the low molecular weight siloxane fluid under shear force, to provide a uniform silicone paste. The silicone paste has excellent spreadability upon rubbing, and possesses unique rheological properties in being thixotropic and shear thinning. The silicone paste can be easily emulsified with water to form a stable uniform emulsion, without using a surfactant to allow normally immiscible materials to become intimately mixed.

A method of making a silicone elastomer comprising reacting:

(A) an .tbd.Si--H containing polysiloxane of the formula R.sub.3 SiO(R'.sub.2 SiO).sub.a (R"HSiO).sub.b SiR.sub.3 or the formula (R'.sub.2 SiO).sub.a (R"HSiO).sub.b, and optionally an .tbd.Si--H containing polysiloxane of the formula HR.sub.2 SiO(R'.sub.2 SiO).sub.c SiR.sub.2 H or an .tbd.Si--H containing polysiloxane of the formula HR.sub.2 SiO(R'.sub.2 SiO).sub.a (R"HSiO).sub.b SiR.sub.2 H, where R, R', and R" are alkyl groups with 1-6 carbon atoms, a is 0-250, b is 1-250, and c is 0-250;
and
(B) a mono-alkenyl polyether of the formula CH.sub.2 .dbd.CH(CH.sub.2).sub.x O(CH.sub.2 CH.sub.2 O).sub.y (CH.sub.2 CH.sub.3 CHO).sub.z T, or the formula CH.sub.2 .dbd.CH-Q-O(CH.sub.2 CH.sub.2 O).sub.y (CH.sub.2 CH.sub.3 CHO).sub.z T, where T is hydrogen, a C.sub.1 -C.sub.10 alkyl group, an aryl group, or a C.sub.1 -C.sub.20 acyl group;
Q is a divalent linking group containing unsaturation;
x is 1-6, y is zero or 1-100;
and z is zero or 1-100;
provided y and z are both not zero;
in the presence of a platinum catalyst, until an .tbd.Si--H containing polysiloxane with polyether groups is formed;
and reacting:
(C) the .tbd.Si--H containing polysiloxane with polyether groups;
(D) an unsaturated hydrocarbon selected from the group consisting of alpha, omega-dienes of the formula CH.sub.2 .dbd.CH(CH.sub.2).sub.x CH.dbd.CH.sub.2, alpha, omega-diynes of the formula CH.tbd.C(CH.sub.2).sub.x C.tbd.CH, and alpha, omega-ene-ynes of the formula CH.sub.2 .dbd.CH(CH.sub.2).sub.x C.tbd.CH, where x is 1-20;
in the presence of
(E) a solvent selected from the group consisting of (i) organic compounds, (ii) compounds containing a silicon atom, (iii) mixtures of organic compounds, (iv) mixtures of compounds containing a silicon atom, and (v) mixtures of organic compounds and compounds containing a silicon atom;
and in the presence of a platinum catalyst, until a silicone elastomer is formed by crosslinking and addition of .tbd.SiH across double or triple bonds in the unsaturated hydrocarbon.

11 more elements

Abstract

Claims18