LIGHTWEIGHT PARTICLES AND COMPOSITIONS CONTAINING THEM
Disclosed are particles that have an exterior surface coated with a thin polymeric coating, such as a coating that includes a sulfur-containing polymer. Also disclosed are compositions, such as fuel-resistant sealant and coating compositions, which include such particles. Aerospace vehicles having an aperture at least partially sealed with a sealant deposited from such a sealant composition are also disclosed.
1 . A particle comprising an exterior surface having a thin coating deposited thereon, wherein thin coating comprises a reaction product of reactants comprising:
(a) an aminoplast resin; and
(b) a compound comprising hydroxyl groups.
2 . The particle of claim 1 , wherein the particle is lightweight.
3 . The particle of claim 1 , wherein the particle comprises a thermally expandable capsule.
4 . A method of using the particle of claim 1 , comprising dispersing the particle in a composition comprising a binder.
5 . A composition comprising:
(a) a polymeric film-forming binder comprising reactive functional groups;
(b) optionally a crosslinking agent having functional groups reactive with the functional groups of the polymeric film-forming binder; and
(c) particles dispersed in the binder, wherein the particles comprise an exterior surface having a thin coating deposited thereon, wherein the thin coating comprises a polymer comprising reactive functional groups that are reactive with the functional groups of (a) and/or (b).
6 . The composition of claim 5 , wherein the thin coating comprises a thiol functional polymer.
7 . The composition of claim 6 , wherein the thiol functional polymer comprises the reaction product of reactants comprising:
(1) an aminoplast resin; and
(2) a polythiol.
8 . The composition of claim 7 , wherein the polythiol comprises a dithiol.
9 . The composition of claim 5 , wherein the binder comprises a sulfur-containing polymer.
10 . The composition of claim 9 , wherein the binder comprises a polythioether.
11 . The composition of claim 5 , wherein the particle comprises a thermally expandable capsule.