Method for coating containers and other articles and coated articles produced thereby

摘要

In a method for producing an article coated with polytetrafluoroethylene the active surface of the material from which the article is made is attacked with an acidic solution and then without employing pressure, polytetrafluoroethylene is deposited from an aqueous solution or dispersion on the attacked surface. Two blanks 1 of the required size each to produce an article, such as a cooking utensil, are mounted adjacent separated by a rubber ring 3 and the space between them is evacuated by applying external pressure or through a valve provided in the ring. The blanks are submerged in a tank 7 containing an acidic solution. For aluminium blanks the solution may comprise hydrofluoric acid and hydrochloric acid. A number of pairs of blanks may be treated at the same time by suspending them from a rod 13 above a tank of acid as shown in Fig. 5. A single blank may be treated by using a suspension having a suction grip 10. Each blank is then coated with a film of polytetrafluoroethylene by mounting the blank on a rotatable support 16 and depositing the polytetrafluoroethylene on the centre of the blank from a nozzle 18. Excess coating is recovered from a tank 15 surrounding the support. The coating is then baked preferably using a hot platen under pressure. The process is repeated to obtain the required thickness of film. The blank is then formed to the required shape of an article such as a frying pan 21. Specification 815,756 is referred to.ALSO:In casting aluminium and like cooking utensils with polytetrafluoroethylene to prevent adhesion during cooking, the active surface of the material from which the article is made is attacked with an acidic solution and then without employing pressure, polytetrafluoroethylene is deposited from an aqueous solution or dispersion on the attacked surface. The coating may be applied to the blanks from which the utensil, e.g. a frying-pan, is to be made only one surface of the blank being exposed to the treatment. The coating is then baked preferably using a hot platen under pressure. The process is repeated to obtain the required thickness of film. Specification 815,756, [Group III], is referred to.