Highly chemically resistant thermoplastic vulcanizates based on fluorocarbon polymers and seal-gasket products made with same

A process for producing a fluorine containing thermoplastic vulcanizate composition comprising the steps of:

• melt blending at least one uncured melt formable thermoplastic fluorocarbon resin with a blend of fluorine containing elastomers, where at least one of the elastomeric components is a vinylidene fluoride/tetrafluoroethylene/propylene terpolymer, and where the elastomers and thermoplastic is melt blended at a temperature higher than the melting temperature of the thermoplastic;
• and
• vulcanizing the fluorine containing elastomers while maintaining the shear mixing forces on the blend thereby forming a dual phase composition comprising a cured dispersed particle phase of the fluorine containing elastomers suspended in an uncured melt formable continuous phase of the fluorocarbon resin.

A product formed according to a process comprising the steps of:

• melt blending at least one uncured melt formable thermoplastic fluorocarbon resin and a blend of fluorine containing elastomers, where at least one of the components of the blend of elastomers is a vinylidene fluoride/tetrafluoroethylene/propylene terpolymer, and where the blend of elastomers and thermoplastic is melt blended at a temperature higher than the melting temperature of the thermoplastic;
• and
• partitioning the mixture into a dual phase composition by vulcanizing the fluorine containing elastomers while maintaining shear mixing forces, thereby forming an uncured continuous phase of the thermoplastic fluorocarbon resin and a cured dispersed phase of the fluorine containing elastomers.

A fluorine containing thermoplastic vulcanizate composition comprising a continuous phase of at least one uncured melt formable thermoplastic resin and a blend of at least two cured fluorine containing elastomers forming a dispersed elastomer phase where one of the elastomers is a vinylidene fluoride/tetrafluoroethylene/propylene terpolymer;

• wherein the vinylidene fluoride/tetrafluoroethylene/propylene terpolymer comprises between about 23 and about 75 weight percent of the total dispersed elastomer phase, and the total dispersed elastomer phase comprises from between about 56 and about 67 weight percent based on the total amount of the continuous phase and the disperse phase combined.