Patent GB-997096-A (GB)
Title: Polyblends of polytetrafluoroethylene and fluorocarbon elastomer latices
Inventor: ROBB LESTER EUGENE
IPC: C09D127/16
Filed: 1961-09-07
Abstract: A coating composition comprises a mixture of an aqueous latex of a tetrafluoroethylene thermoplastic polymer and an aqueous latex of an elastomeric copolymer of vinylidene fluoride and either perfluoropropene or trifluorochloroethylene, the weight ratio of said thermoplastic polymer to said elastomeric copolymer being from 1 : 1 to 1 : 200.  The tetrafluoroethylene thermoplastic polymer includes tetrafluoroethylene homopolymer as well as tetrafluoroethylene polymerized with up to 5 mol. per cent of other fluorinated olefines, e.g. vinylidene fluoride. Elastomeric copolymers of trifluorochloroethylene and vinylidene fluoride contain trifluorochlorethylene in an amount between 20 and 69 mol. per cent. Elastomeric copolymers of perfluoropropene and vinylidene fluoride contain from 15 to 60 mol. per cent of perfluoropropene and can be formed by polymerizing 20 to 80 mol. per cent of perfluoropropene with vinylidene fluoride at 0 DEG  to 100 DEG  C. and at a pH between 2 and 10.  Free radical forming promoters or ionic type promoters may be added.  Also emulsifiers, e.g. halogenated aliphatic carboxylic acids and salts, activators, e.g. water-soluble reducing agents and accelerators, e.g. water-soluble variable valence metal salts, may be added to the aqueous polymerization mixture.  The coating composition may be used directly to coat various substrates or it may be kept for some time before it is to be used and preferably in this case a latex stabilizing agent, e.g. a fluorinated carboxylic acid or salt, is added.  Other suitable stabilizers include the sodium salt of sulphonated methyl taurine, aryl alkyl polyethers, amine acetates. Inert fillers, e.g. silica, carbon black, and heat stabilizers, e.g. metal oxides and sulphides, may be added.  The coating composition may be compounded, moulded and vulcanized and the elastomer molecules may be cross-linked by the addition of a vulcanizing agent, e.g. polyamines or an inorganic peroxide.ALSO:A composition comprising an aqueous latex of a tetrafluoroethylene thermoplastic polymer and an aqueous latex of an elastomeric copolymer of vinylidene fluoride and either perfluoropropene or trifluorochloroethylene, the weight ratio of said thermoplastic polymer to said elastomeric copolymer being from 1 : 1 to 1 : 200, may be used to coat substrates of metal such as steel, brass and copper, wood, rubber, plastics such as polyethylene and fabrics such as cotton, nylon, wool, fibre glass and "Dacron" (Registered Trade Mark), by spraying, knife coating or dipping and then drying.  The tetrafluoroethylene polymer may be the homopolymer or it may be copolymerized with up to 5 mol per cent of other fluorinated olefines, e.g. vinylidene fluoride. Latex stabilizing agents and inert fillers may be added to the composition. The composition may be coagulated and dried and/or crosslinked by adding vulcanizing agents.  In the examples: (1) fibre glass mat is coated by dipping into a mixture of a tetrafluoroethylene homopolymer latex, a trifluorochloroethylene-vinylidene fluoride latex, a zinc oxide dispersion and hexamethylenediamine, drying at 250  DEG F. and then curing in an air oven at 300  DEG F. for 2 hours; (2) fibre glass cloth is similarly coated by dipping into a mixture of a tetrafluoroethylene homopolymer latex and a perfluoropropene vinylidene fluoride latex stabilized with the potassium salt of 3,5,7,8-tetrachloro, unadecafluoro caprylic acid.