Patent GB-966814-A (GB)
Title: Perfluorocarbon polymer coating compositions
IPC: C08L27/18
Filed: 1962-08-16
Abstract: Water-dilutable aqueous dispersion coating compositions comprise (A) colloidal particles of polytetrafluoroethylene or a copolymer of tetrafluoroethylene and hexafluoropropylene dispersed in a continuous aqueous phase, (B) a solution of a heat-convertible organopolysiloxane resin containing structural units of formula: <FORM:0966814/C3/1> where R and R1 are hydrocarbon radicals, in a water-immiscible organic solvent as dispersed phase, (C) sufficient anionic surfactants to maintain the stability of the dispersion of polymer and solution of polysiloxane resin, and (D) chromic acid. The compositions may also include non-ionic surfactants and polybasic oxyacids of phosphorus and sulphur.  The preferred polysiloxane resins are methyl phenyl polysiloxanes containing 1 to 2 methyl and phenyl groups per silicon atom and 0.5 to 2 methyl groups per phenyl group.  Specified solvents are toluene, xylene, benzene, petroleum naphtha, mineral spirits, hexane, cyclohexane, esters, ketones and ethers.  Specified anionic surfactants are sodium alkyl sulphates, sodium alkyl sulphonates, sodium alkylaryl sulphonates and sodium naphthalene sulphonates condensed with formaldehyde. Specified non-ionic surfactants are condensates of alkylene oxides with alkylphenols, alcohols and mercaptans.  Specified oxyacids of phosphorus and sulphur are orthophosphoric, pyrophosphoric, sulphuric and sulphurous acids.  The compositions may also comprise pigments, e.g. metal oxides, hydroxides, carbonates, chromates, silicates, sulphates, phosphates, carbon black, silica, montmorillonite clays; bodying agents, e.g. methyl cellulose, dimethyl dioctyl ammonium bentonite clay and carboxylic vinyl polymers; and flow control agents.  Examples describe compositions comprising methyl phenyl polysiloxane resin, xylene, octylphenoxypolyethoxyethanol, chromic acid and orthophosphoric acid together with (1) sodium lauryl sulphate, polytetrafluoroethylene chromic oxide, titanium dioxide and toluene; (2) sodium lauryl sulphate, polytetrafluoroethylene, titanium dioxide and toluene; (3) sodium lauryl sulphate, polytetrafluoroethylene, tetrafluoroethylene/hexafluoropropylene copolymer and titanium dioxide; (4) sodium lauryl sulphate, tetrafluoroethylene/hexafluoropropylene copolymer, titanium dioxide and toluene; (5) sodium lauryl sulphate, polytetrafluoroethylene, titanium dioxide and toluene; and (6) polytetrafluoroethylene, tetrafluoroethylene/hexafluoropropylene copolymer, formaldehydenaphthalene sodium sulphonate, carbon black and aluminium silicate.  The compositions may be used for coating metals, glass, ceramics, wood, paper, textiles, rubber and synthetic elastomers. Specifications 631,504, 631,570 and 829,600 are referred to.ALSO:Substrates, e.g. of metal, glass and ceramic, may be coated with compositions comprising (A) colloidal particles of polytetrafluoroethylene or a tetrafluoroethylene/hexafluoropropylene copolymer dispersed in a continuous aqueous phase, (B) a solution of a heat-convertible organo-polysiloxane resin containing structural units of formula <FORM:0966814/B1-B2/1> where R and R1 are hydrocarbon radicals, in a water-immiscible organic solvent or dispersed phase, (C) sufficient anionic surfactant to maintain the stability of the dispersion of polymer and solution of polysiloxane resin, and (D) chromic acid.  The compositions may also comprise non-ionic surfactants, polybasic oxyacids of sulphur and phosphorus, pigments, extenders and bodying agents.  The compositions may be applied by spraying, brushing, dipping or roller coating to iron, steel, copper, bronze, brass, nickel, aluminium, titanium, tungsten, alloys, glass and ceramics, and the coatings cured by heating.  The compositions of the invention may be applied in conjunction with polytetrafluoroethylene suspension primers and top coats.  Examples describe the coating of (1) aluminium ice cube trays and electric grills with compositions comprising polytetrafluoroethylene, methyl phenyl polysiloxane, xylene, toluene, sodium lauryl sulphate, octylphenoxypolyethoxyethanol, chromic acid, orthophosphoric acid, chromic oxide and titanium dioxide; (2) aluminium griddles and aluminium and steel panels with compositions comprising polytetrafluoroethylene, methyl phenyl polysiloxane, xylene, toluene, sodium lauryl sulphate, octylphenoxypolyethoxyethanol, chromic acid, orthophosphoric acid and titanium dioxide; aluminium and steel panels with compositions comprising (3) polytetrafluoroethylene, tetrafluoroethylene/hexafluoropropylene copolymer, methyl phenyl polysiloxane, xylene, toluene, sodium lauryl sulphate, octylphenoxypolyethoxyethanol, chromic acid, orthophosphoric acid and titanium dioxide, and (4) tetrafluoroethylene/hexafluoropropylene copolymer, methyl phenyl polysiloxane, xylene, toluene, sodium lauryl sulphate, octylphenoxypolyethoxyethanol, chromic acid, orthophosphoric acid and titanium dioxide; and steel panels with compositions comprising (6) polytetrafluoroethylene, tetrafluoroethylene/hexafluoropropylene copolymer, methyl phenyl polysiloxane, xylene, toluene, sodium sulphonate of naphthaleneformaldehyde condensate, octylphenoxypolyethoxyethanol, chromic acid, orthophosphoric acid, carbon black and aluminium silicate.  Specifications 631,504, 631,570 and 829,600 are referred to.