POLYSILOXANE FOAM COMPOSITIONS AND METHODS RELATED THERETO
Described is a curable organopolysiloxane foam-forming composition that can be used to produce an organopolysiloxane foam. The curable organopolysiloxane foam-forming composition contains a particle containing a platinum group catalyst and a thermoplastic polymer. The thermoplastic polymer shields the other components in the curable organopolysiloxane foam-forming composition from the platinum group catalyst. As such, when sufficient heat is applied the thermoplastic polymer softens and/or melts, which exposes the platinum group catalyst to the other components to start the foam making process.
1 . A curable organopolysiloxane foam-forming composition comprising:
(A) 100 parts by weight of an organopolysiloxane represented by the average unit formula:
wherein, R is a substituted or unsubstituted monovalent hydrocarbon group, and “a” is a number from 1.0 to 2.4, and having at least an average of 1.5 alkenyl groups in a molecule;
(B) from 1 to 70 parts by weight an organopolysiloxane having at least an average of 1.5 silicon-bonded hydrogen atoms in a molecule;
(C) from 0.1 to 50 parts by weight of a blowing agent; and
(D) from 0.00001 to 20 parts by weight of a particle comprising:
i. a platinum-group catalyst; and
ii. a molecular weight controlled thermoplastic polymer having a T g or softening temperature of at least 20° C. selected from the group consisting of:
1. polystyrene or a co-polymer thereof having a M w from about 500 g/mol to about 30,000 g/mol, and a polydispersity index (PDI) of less than 2;
2. polymethylmethacrylate or a co-polymer thereof having a M w from about 500 g/mol to about 30,000 g/mol, and a PDI of less than 2; and
3. polyacrylonitrile or a co-polymer thereof having a M w from about 500 g/mol to about 30,000 g/mol, and a PDI of less than 2:
wherein the platinum-group catalyst is fully encapsulated within the thermoplastic polymer.
2 . The curable organopolysiloxane foam-forming composition of claim 1 , wherein the organopolysiloxane in (A) is an alkenyl-terminated organopolysiloxane, an alkenyl-pendant organopolysiloxane, or an alkenyl-terminated and alkenyl-pendant organopolysiloxane.
3 . The curable organopolysiloxane foam-forming composition of claim 1 , wherein the organopolysiloxane in (B) is a hydride-terminated organopolysiloxane, a hydride-pendant organopolysiloxane, or a hydride-terminated and hydride-pendant organopolysiloxane.
4 . The curable organopolysiloxane foam-forming composition of claim 1 , wherein the curable organopolysiloxane foam-forming composition further comprises from more than 0 parts to 5 parts by weight of a reaction inhibitor.
5 . The curable organopolysiloxane foam-forming composition of claim 1 , wherein the curable organopolysiloxane foam-forming composition further comprises from more than 0 parts to 150 parts by weight of a filler, a treating agent, or a surfactant, or a combination thereof.
6 . The curable organopolysiloxane foam-forming composition of claim 5 , wherein the filler is an inorganic filler.
7 . The curable organopolysiloxane foam-forming composition of claim 1 , wherein the organopolysiloxane in part (B) is present from 5 to 40 parts by weight.
8 . The curable organopolysiloxane foam-forming composition of claim 1 , wherein the blowing agent is present from 5 to 40 parts by weight.
9 . The curable organopolysiloxane foam-forming composition of claim 1 , wherein the particle is present from 0.01 to 10 parts by weight.
10 . The curable organopolysiloxane foam-forming composition of claim 1 , wherein the thermoplastic polymer is polystyrene or a co-polymer thereof having a M w from about 500 g/mol to about 30,000 g/mol, and a polydispersity index (PDI) of less than 2.
11 . The curable organopolysiloxane foam-forming composition of claim 10 , wherein the polystyrene or a co-polymer thereof has a M w from about 500 g/mol to about 15,000 g/mol and a PDI of less than 1.2.
12 . The curable organopolysiloxane foam-forming composition of claim 1 , wherein the thermoplastic polymer is polymethylmethacrylate or a co-polymer thereof having a M w from about 500 g/mol to about 30,000 g/mol, and a polydispersity index (PDI) of less than 2.
13 . The curable organopolysiloxane foam-forming composition of claim 12 , wherein the polymethylmethacrylate or a co-polymer thereof has a M w from about 500 g/mol to about 15,000 g/mol and a PDI of less than 1.2.
14 . The curable organopolysiloxane foam-forming composition of claim 1 , wherein the thermoplastic polymer is polyacrylonitrile or a co-polymer thereof having a M w from about 500 g/mol to about 30,000 g/mol, and a polydispersity index (PDI) of less than 2.
15 . The curable organopolysiloxane foam-forming composition of claim 14 , wherein the polyacrylonitrile or a co-polymer thereof has a M w from about 500 g/mol to about 15,000 g/mol and a PDI of less than 1.2.
16 . The curable organopolysiloxane foam-forming composition of claim 1 , wherein the particle has an average particle diameter from about 0.01 μm to about 100 μm.
17 . The curable organopolysiloxane foam-forming composition of claim 1 , wherein the particle comprises from about 0.01 wt % to about 20 wt % of the platinum-group catalyst.
18 . The curable organopolysiloxane foam-forming composition of claim 1 , wherein the curable organopolysiloxane foam-forming composition is a one-part curable organopolysiloxane foam-forming composition.
19 . The curable organopolysiloxane foam-forming composition of claim 1 , wherein the curable organopolysiloxane foam-forming composition is a two-part curable organopolysiloxane foam-forming composition.
20 . The curable organopolysiloxane foam-forming composition of claim 1 , wherein the curable organopolysiloxane foam-forming composition is a homogenous composition.
21 . The curable organopolysiloxane foam-forming composition of claim 1 , wherein the molecular weight controlled thermoplastic polymer having a T g or softening temperature from 30° C. to 120° C.
22 . A method or producing an organopolysiloxane foam comprising the steps of:
a) providing the curable organopolysiloxane foam-forming composition of claim 1 ; and
b) heating the curable organopolysiloxane foam-forming composition to a temperature effective to soften or melt the thermoplastic polymer to release the platinum-group catalyst, thereby promoting the reaction that produces the organopolysiloxane foam.
23 . (canceled)
24 . (canceled)