Lightweight particles and compositions containing them

Abstract

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.