Elastomeric shaft seal formed without oven post curing

Abstract

An elastomeric seal ( 20 ), such as a shaft seal for automotive vehicle applications, includes an elastomeric compound ( 22 ) chemically coupled to a metal sealing ring ( 24 ) and is formed without an oven post curing step. The elastomeric seal ( 20 ) provides exceptional physical properties, similar to those of elastomeric seals of the prior art formed with an oven post curing step. The elastomeric seal ( 20 ) has an elastic modulus of 6.0 MPa to 13.0 MPa and a tensile strength of 11.1 MPa to 14.8 MPa. The elastomeric compound ( 22 ) includes 52.0 to 68.0 wt. % fluoroelastomer, 20.0 to 35.0 wt. % calcium silicate, and 5.0 to 15.0 wt. % diatomite. The elastomeric compound ( 22 ) is fully cured and chemically coupled to the metal sealing ring ( 24 ) during the compression or injection molding step, and thus an oven post curing step is not required.

What is claimed is: 
     
         1 . An elastomeric seal ( 20 ), comprising:
 a sealing ring ( 24 ) including a metal material and presenting a plurality of surfaces extending around a center axis (A);   an elastomeric compound ( 22 ) chemically coupled to at least one of said surfaces of said sealing ring ( 24 );   said elastomeric compound ( 22 ) including, in wt. % of said elastomeric compound ( 22 ) 52.0 to 68.0 wt. % FKM; and   wherein said elastomeric seal ( 20 ) is produced by a process comprising the steps of: molding said elastomeric compound ( 22 ) to said sealing ring ( 24 ); chemically coupling said elastomeric compound ( 22 ) to said sealing ring ( 24 ); and the chemically coupling step being during the molding step and without an oven post curing step after the molding step.   
     
     
         2 . The elastomeric seal ( 20 ) of  claim 1 , wherein said elastomeric compound ( 22 ) has a cohesive failure after bond peel test. 
     
     
         3 . The elastomeric seal ( 20 ) of  claim 1 , wherein said elastomeric compound ( 22 ) has an elastic modulus of at least 6.0 MPa. 
     
     
         4 . The elastomeric seal ( 20 ) of  claim 1 , wherein said elastomeric compound ( 22 ) has a tensile strength of at least 6.0 MPa. 
     
     
         5 . The elastomeric seal ( 20 ) of  claim 1  wherein the molding step includes: disposing said elastomeric compound ( 22 ) and said sealing ring ( 24 ) a molding apparatus; heating said elastomeric compound ( 22 ) to a temperature of at least 175° C. for at least 3 minutes; and applying a pressure to said elastomeric compound ( 22 ) for at least 3 minutes. 
     
     
         6 . The elastomeric seal ( 20 ) of  claim 5 , wherein the process of forming said elastomeric seal ( 20 ) further comprises removing said elastomeric seal ( 20 ) from the molding apparatus after the molding step and maintaining said elastomeric compound ( 22 ) at a temperature less than 100° C. after the molding step. 
     
     
         7 . The elastomeric seal ( 20 ) of  claim 1  wherein the oven post curing step would include heating said elastomeric compound ( 22 ) to a temperature of at least 170° C. for at least one hour. 
     
     
         8 . The elastomeric seal ( 20 ) of  claim 1 , wherein said elastomeric compound ( 22 ) further comprises 20.0 to 35.0 wt. % calcium silicate and 5.0 to 15.0 wt. % diatomite. 
     
     
         9 . The elastomeric seal ( 20 ) of  claim 1 , wherein said elastomeric compound ( 22 ) further comprises 20.0 to 35.0 wt. % calcium silicate, 5.0 to 15.0 wt. % diatomite, 1.0 to 5.0 wt. % carbon black, 4.0 to 10.0 wt. % metal oxides, 0.5 to 3.0 wt. % bisphenol AF, 0.1 to 0.5 wt. % accelerator, and 0.2 to 2.0 wt. % processing aids. 
     
     
         10 . The elastomeric seal ( 20 ) of  claim 9  wherein said metal oxides include, in wt. % of said elastomeric compound ( 22 ), 3.0 to 5.0 wt. % magnesium oxide, 0.5 to 2.0 wt. % calcium oxide, and 0.3 to 3.0 wt. % calcium hydroxide. 
     
     
         11 . An elastomeric seal ( 20 ) for contacting a metal shaft of an automotive vehicle application, comprising:
 a sealing ring ( 24 ) presenting a top surface and an oppositely facing bottom surface extending circumferentially around a center axis (A);   said sealing ring ( 24 ) presenting an inner diameter surface facing toward said center axis (A) for contacting the metal shaft and an oppositely facing outer diameter surface;   said outer diameter surface and said inner diameter surface extending circumferentially around said center axis (A);   said sealing ring ( 24 ) being formed of a metal material;   said metal material being steel;   an elastomeric compound ( 22 ) disposed on and chemically coupled to said sealing ring ( 24 );   said elastomeric compound ( 22 ) extending along at least one of said surfaces of said sealing ring ( 24 );   said elastomeric compound ( 22 ) comprising, in wt. % of said elastomeric compound ( 22 ), 52.0 to 68.0 wt. % FKM; 20.0 to 35.0 wt. % calcium silicate; 5.0 to 15.0 wt. % diatomite; 1.0 to 5.0 wt. % carbon black; 4.0 to 10.0 wt. % metal oxides; said metal oxides including, in wt. % of said elastomeric compound, 3.0 to 5.0 wt. % magnesium oxide, 0.5 to 2.0 wt. % calcium oxide, and 0.3 to 3.0 wt. % calcium hydroxide; 0.5 to 3.0 wt. % bisphenol AF, 0.1 to 0.5 wt. % accelerator; and  0 . 2  to  2 . 0  wt. % processing aids; said processing aides including at least one of wax, fatty acid derivatives, organosilicones, fluoropolyether derivatives, and octadecylamine;   said elastomeric seal ( 20 ) produced by a process including no oven post cure step;   the process of forming said elastomeric seal ( 20 ) comprising the steps of:   providing said elastomeric compound ( 22 );   the step of providing said elastomeric compound ( 22 ) including mixing components, wherein the components include, in wt. % of the total mixture of components, 52.0 to 68.0 wt. % FKM, 20.0 to 35.0 wt. % calcium silicate, 5.0 to 15.0 wt. % diatomite, 1.0 to 5.0 wt. % carbon black, 4.0 to 10.0 wt. % metal oxides, 0.5 to 3.0 wt. % bisphenol AF, 0.1 to 0.5 wt. % accelerator, and 0.2 to 2.0 wt. % processing aids;   providing said sealing ring ( 24 ) including said plurality of surfaces extending circumferentially around said center axis (A);   cleaning said surfaces of said sealing ring ( 24 );   disposing said elastomeric compound ( 22 ) on said sealing ring ( 24 );   disposing said elastomeric compound ( 22 ) and said sealing ring ( 24 ) in a molding apparatus, wherein the molding apparatus is an injection mold or a compression mold;   molding said elastomeric compound ( 22 ) to said sealing ring ( 24 ) in the molding apparatus;   the molding step including chemically coupling said elastomeric compound ( 22 ) to at least one surface of said sealing ring ( 24 );   the molding step including applying a pressure to said elastomeric compound ( 22 ) for at least 3 minutes while said elastomeric compound ( 22 ) is disposed in the molding apparatus;   the molding step including heating said elastomeric compound ( 22 ) to a temperature of 175° C. for at least 3 minutes while said elastomeric compound ( 22 ) is disposed in the molding apparatus;   chemically coupling said elastomeric compound ( 22 ) to said sealing ring ( 24 ) during the molding step;   the chemically coupling step including providing said elastomeric compound ( 22 ) with an elastic modulus of 6.0 MPa to 13.0 MPa when tested according to ASTM D412;   the chemically coupling step including providing said elastomeric compound ( 22 ) with a tensile strength of 11.1 MPa to 14.8 MPa;   removing said elastomeric seal ( 20 ) from the molding apparatus after the molding step;   maintaining said elastomeric seal ( 20 ) at ambient temperature after removing said elastomeric seal ( 20 ) from the molding apparatus; and   the chemically coupling step being performed without an oven post curing step after removing said elastomeric seal ( 20 ) from the molding apparatus, wherein the oven post curing step would include heating said elastomeric seal ( 20 ) to a temperature of at least 170° C. for at least one hour in an oven after removing said elastomeric seal ( 20 ) from the molding apparatus.