A novel technique for coating polypropylene yarns with polytetrafluorоethylene

Abstract

The article is devoted to an easy and effective method of giving polypropylene yarns the same extremely high chemical resistance as fluoropolymers yarns has. The method is based on the formation of an ultrathin, continuous and even coating of polytetrafluoroethylene on a surface of each filament forming yarn. The adhesion of a polytetrafluoroethylene coating to polypropylene is provided by applying of a diluted suspension of high-disperse polytetrafluoroethylene on a surface of a semi-hardened polypropylene yarn at the oiling stage. Later, the yarn is subjected to orientational stretching. In the process of stretching the coating becomes uniform and oriented thanks to an ability of polytetrafluoroethylene to pseudo-fluidity and a high coefficient of thermal expansion. The polypropylene yarn with a polytetrafluoroethylene coating gets an extremely high resistance to the influence of nitric acid and sodium hydroxide. Its frictional coefficient is close to the frictional coefficient of polytetrafluoroethylene and the strength is much higher than the strength of a common polypropylene yarn. The applied coating has a high resistance to the intensive abrasive action.