Hard paper

Hard paper is a thermosetting fibre composite material made from several layers of technical paper impregnated with phenolic resin (PF). It has a brownish colour and is formed into semi-finished products, which are then machined. Pertinax is a well-known trade name for hard paper. Nowadays these composite materials are increasingly being replaced by modern thermoplastics, so mainly circuit boards and transformer parts are made from hard paper.