Curable elastomer compositions with low temperature sealing capability

Abstract

Curable sealant compositions having low temperature sealing ability improved over convention curable sealing compositions. The composition is flowable and can be cured to a cross linked form to provide cured reaction products that exhibit elastomeric properties. The curable elastomeric sealant composition can include a cross linkable elastomeric oligomer; an initiator or cross-linking agent; a glassy monomer and/or a rubbery monomer; and optionally one or more additives. Cured reaction products of the composition have a single Tg and retain a higher sealing force at low temperatures (but above the cured product Tg) as compared to a curable composition made from the same cross linkable elastomeric oligomer but without the glassy and/or rubbery monomer.

What is claimed: 
     
         1 . A cross linkable sealant composition, prepared from:
 a cross linkable elastomeric oligomer having a Tg;   a monomer having a Tg higher than the elastomeric oligomer Tg or a combination of monomers having an average Tg for the combination higher than the elastomeric oligomer Tg;   an initiator or cross-linking agent; and   optionally at least one of catalyst; filler; antioxidant; reaction modifier; adhesion promoter; diluent and coloring agent;   wherein a cured reaction product of the composition has a single Tg and retains a higher sealing force at temperatures above the cured product Tg as compared to a similar composition made as above without the monomer.   
     
     
         2 . The composition of  claim 1  wherein the cross linkable elastomeric oligomer comprises reactive moieties adjacent each end and the oligomer backbone comprises polyisobutylene. 
     
     
         3 . The composition of  claim 1  wherein the cross linkable elastomeric oligomer backbone comprises about 1% to about 100% polyisobutylene. 
     
     
         4 . The composition of  claim 1  wherein the cross linkable elastomeric oligomer has spacing between reactive moieties to provide the oligomer with elastomeric properties. 
     
     
         5 . The composition of  claim 1  wherein the cross linkable elastomeric oligomer is a telechelic, (meth)acrylate terminated polyisobutylene. 
     
     
         6 . The composition of  claim 1  wherein the monomer is reacted to the cross linkable elastomeric oligomer. 
     
     
         7 . The composition of  claim 1  wherein cured reaction products are free of first and second order thermodynamic transitions as shown by DSC. 
     
     
         8 . A method of increasing the low temperature sealing force of a cured elastomeric sealant comprising:
 providing a cross linkable sealant composition, prepared from a cross linkable elastomeric oligomer, an initiator or cross-linking agent, and optionally at least one of catalyst, filler, antioxidant, reaction modifier, and coloring agent; wherein cured reaction products of the sealant composition have a Tg; and   adding about 10 to about 30% by weight of sealant composition of a monomer having a Tg higher than the elastomeric oligomer Tg or a combination of monomers having an average Tg for the combination higher than the elastomeric oligomer Tg to form an improved sealant composition;   wherein cured reaction products of the improved sealant composition have a single Tg and have a higher sealing force at temperatures between their Tg and 0° C. than cured reaction products of the sealant composition.   
     
     
         9 . A component defining an internal chamber, comprising:
 a first predetermined sealing surface in fluid communication with the chamber;   a second predetermined sealing surface aligned with the first sealing surface and in fluid communication with the chamber; and   a cured reaction product of the composition of  claim 1  disposed between the first and second predetermined sealing surfaces and sealing the chamber.   
     
     
         10 . The component of  claim 9  wherein the first sealing surface and the second sealing surface do not move in relationship to each other. 
     
     
         11 . The component of  claim 9  wherein the reaction product is adhesively bonded to only one of the first and second sealing surfaces. 
     
     
         12 . The component of  claim 9  wherein the reaction product is adhesively bonded to both the first and second sealing surfaces. 
     
     
         13 . The component of  claim 9  wherein the reaction product is liquid injection molded or molded on the sealing surface. 
     
     
         14 . A method of using the curable composition of  claim 1  as a liquid gasketing composition, comprising:
 providing the composition of  claim 1 ; 
 dispensing the composition onto a first predetermined sealing surface, 
 aligning the first predetermined sealing surface and dispensed composition with a second predetermined sealing surface; and 
 exposing the dispensed the composition to conditions appropriate to effect cure thereof, wherein cured reaction products of the composition have a single Tg and retain a positive sealing force at temperatures above the cured product Tg. 
 
     
     
         15 . The method of  claim 14  wherein the composition is cured while in contact with the first and second sealing surfaces.