Coating compositions comprising a polysulfone and fluorocarbon polymer

Abstract

A coating composition is provided which comprises (a) 10% to 90% by weight of at least one thermoplastic aromatic .[.polysulphones.]. .Iadd.polysulphone .Iaddend.preferably having a reduced viscosity of at least 0.3 (measured at 25° C. on a solution in dimethyl formamide containing 1 g of polymer in 100 cm 3 of solution) and (b) 90% to 10% by weight of at least one fluorocarbon polymer.

We claim: .[.1. A coating composition which comprises a polymer mixture of (a) 10% to 90% by weight of at least one thermoplastic aromatic polysulphone having repeat units ##STR8## alone or in conjunction with repeat units selected from at least one of ##STR9## or repeat units (ii) or (iii) in conjunction with repeat units ##STR10## and, correspondingly, 90% to 10% by weight of at least one fluorocarbon polymer selected from polytetrafluoroethylene and copolymers or tetrafluoroethylene with up to 15% by weight of another unsaturated monomer, said composition being in the form of a dispersion of said fluorocarbon polymer dispersed in a solution of said thermoplastic 
     
        aromatic polysulphone in a solvent therefor..]. .[.2.  A composition according to claim 1 in which the concentration of thermoplastic aromatic polysulphone is 15% to 85% by weight..]. .[.3. A composition according to claim 2 in which the concentration of thermoplastic aromatic polysulphone is less than 60% by weight..]. .[.4. A composition according to claim 1 in which the fluorocarbon polymer is poly(tetrafluoroethylene)..]. .[.5. A composition according to claim 1 in which the thermoplastic aromatic polysulphone has repeating units of the formula ##STR11## 
     
     
        .]. .[.6.  A method of coating an article which comprises applying to the article a composition as claimed in claim 1, drying the coated article, and sintering the coating at temperatures of 330° C. to 450° C..]. .[.7. A cooking utensil coated by the method of claim 6..]. .[.8. A composition according to claim 4 in which the fluorocarbon polymer is a polytetrafluoroethylene powder of average particle size of less than 20 μm as measured optically prepared by a process including comminution of a high molecular weight polytetrafluoroethylene..]. .[.9. An article coated by the method of claim 6..]. .Iadd. 10. A coating composition which comprises a polymer mixture of (a) 10% to 90% by weight of at least one thermoplastic aromatic polysulfone having reduced viscosity of at least 0.3 (as measured at 25° C. on a solution of the polymer in dimethyl formamide containing 1 g of polymer in 100 cm 3  of solution) and repeat units ##STR12## only, and, correspondingly, (b) 90% to 10% by weight of at least one lubricant grade polytetrafluoroethylene powder of average particle size less than 20 μm as measured optically prepared by processes including comminution of a high molecular weight polytetrafluoroethylene, said composition being in the form of a dispersion of said lubricant grade polytetrafluoroethylene dispersed in a solution of said thermoplastic 
     
     
        aromatic polysulfone in a solvent therefor. .Iaddend..Iadd. 11.  A composition according to claim 10 in which the concentration of thermoplastic aromatic polysulphone is 15% to 85% by weight. .Iaddend..Iadd. 12. A composition according to claim 11 in which the concentration of thermoplastic aromatic polysulphone is less than 60% by weight. .Iaddend..Iadd. 13. A method of coating an article which comprises applying to the article a composition as claimed in claim 10, drying the coated article, and sintering the coating at a temperature of 330° C. to 450° C. .Iaddend..Iadd. 14. An article coated by the method of claim 13. .Iaddend.