Reduction of silicone foam density using buffers

• US 5,017,624 A
• Filed: 10/15/1990
• Issued: 05/21/1991
• Est. Priority Date: 08/20/1990
• Status: Expired due to Term

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Johnson, Donald S.
• Primary Examiner(s): Foelak, Morton
• Application Number:
  US07/597,253
• Time in Patent Office: 218 Days
• Field of Search: 521/82, 521/88, 521/117, 521/154
• US Class Current: 521/154
• CPC Class Codes: C08J 2383/04 Polysiloxanes
• CPC Class Codes: C08J 9/02 using blowing gases generated by the reacting monomers or modifying agents during the preparation or modification of macromolecules

Abstract

A method is provided for preparing a silicone foam having reduced density of about 5 to about 6 pounds per cubic foot, comprising the step of agitating a mixture of ingredients comprising (A) a silicon composition, comprising by weight: (1) 100 parts of a vinyl-terminated polydiorganosiloxane (2) about 0.5 to about 5 parts by weight of an aqueous buffer solution having a pH in the range of about 9 to about 10; and (3) about 25 to about 140 parts per million of a platinum catalyst; (8) about 2.5 to about 20 parts of a substantially linear hydride polysiloxane (C) about 0.1 to about 15 parts of a cyclic hydride polysiloxane; and (D) about 0.1 to about 5 parts of a hydroxyl source selected from the group consisting of water, organic alcohol, or a mixture of the foregoing.

Claims

1. A silicone foam having a reduced density of about 5 to about 6 pounds per cubic foot, comprising the cured product of a foamable composition comprising by weight:

(A) a silicone composition, comprising by weight;

(1) 100 parts of a vinyl-terminated polydiorganosiloxane of the formula;

##STR4## wherein R and R¹ are selected from the group consisting of substituted or unsubstituted hydrocarbon radicals of from 1 to 20 carbon atoms, such that the polymer contains from 0.0002 to 3% by weight vinyl and x varies such that the viscosity of the polymer varies from 100 to 1,000,000 centipoise at 25°

C.;

(2) about 0.5 to about 5 parts by weight of an aqueous buffer solution having a pH in the range of about 9 to about 10; and

(3) about 25 to about 140 parts per million of a platinum catalyst;

(B) about 2.5 to about 20 parts of a substantially linear hydride polysiloxane having the formula ##STR5## wherein R² is selected independently from the group consisting of hydrogen, alkyl radicals of from 1 to 8 carbon atoms, halo substituted alkyl radicals of from 1 to 8 carbon atoms, aryl radicals of from 6 to 14 carbon atoms, and halo substituted aryl radicals of from 6 to 14 carbon atoms; and

R³ is selected from the group consisting of alkyl radicals of from 1 to 8 carbon atoms, aryl radicals of from 6 to 14 carbon atoms, halo aryl radicals of from 6 to 14 carbon atoms, and haloalkyl radicals of from 3 to 8 carbon atoms;

u and v are integers which can vary sufficiently to provide a hydride polysiloxane having a viscosity of from about 5 to about 10,000 centipoise at 25°

C.;

(C) about 0.1 to about 15 parts of a cyclic hydride polysiloxane having the general formula;

##STR6## wherein R⁶ may be independently hydrogen, an alkyl radical of from 1 to 8 carbon atoms, an aryl radical from 6 to 14 carbon atoms, or a haloalkyl radical of 3 to 8 carbon atoms;

y is an integer having a value of 0 to 5 inclusive, z is an integer having a value of from 1 to 8 inclusive, and the sum of y and z has a value of 3 to 8 inclusive; and

(D) about 0.1 to about 5 parts of a hydroxyl source selected from the group consisting of water, organic alcohol, or a mixture of the foregoing.