Rotary selector gasket mfr. with stiff outer and flexible inner part - by vulcanising inner from synthetic rubber part in mould contg. moulded plastics outer part

摘要

Mfr. of rotary selector gaskets, with a stiff outer pt. and a flexible inner part, is carried out in 2 consecutive stages. The first involves compression moulding the outer part from synthetic resin and the second vulcanisation of the inner part of synthetic rubber in a mould contg. the outer part so that the 2 parts are bonded together stably in a middle zone, forming a differentiated, seamless construction. Steel reinforcement is unnecessary and the use of the plastics insert reduces the cost and improves the reliability ofbthe gasket. The inner pt. has sealing lip(s) and the bonding region of the 2 parts is at the start of the lip. Pref the outer pt. is produced from a mixt. of 100 pts. polyamide resin 50 pts. Al-, Ca-, Mg- silicate and 0-10 pts. C black as fillers, 2-5 pts. paraffin and 2-5 pts. polyethylene and the inner pt. from a mixt. of 100 pts. acrylonitrile, vinyl or fluoride resin, 0-100 pts. A-l, Ca-, Mg-silicates, 5-10 pts. polymer plasticiser, 5-10 pts. Zn salt, 5 pts. rosin, 2-5 pts. paraffin, 0-4 pts. hydroquinoline and 2-5 pts. polyethylene.