The most commonly used thermoplastic resin is nylon (PA), and the high temperature resistant magnet uses polyphenylene sulfide (PPS). The former is a kind of widely used excellent engineering plastic, the highest use temperature of the magnet is about 120℃, while the latter can be used in 180~200℃; The additives include coupling agent, antioxidant, plasticizer, lubricant, etc., before mixing, these components and magnetic powder are fully mixed, and then the mixture is sent to the single spiral or double spiral rod mixing granulator for mixing, to make the particles required for injection or extrusion.
Calendered forming magnet
Rubber is used as adhesive, the most commonly used are buyanogen rubber and chlorinated polyethylene. If there is a high temperature resistance requirement, polyurethane is used. The magnetic powder, resin, vulcanizing agent and other additives are fully mixed, and then mixed in the rubber open mixing machine or closed mixing machine. In the mixing and forming process, the rubber is in the viscoelastic state, rather than in the molten state like the injection/extrusion magnet, so the mixing temperature is relatively low, and the anti-oxidation requirements of the magnetic powder can be correspondingly low. There is a class of thermoplastic elastomers in polymer materials, which exhibit good elasticity close to that of traditional rubber at room temperature, but at the same time can be processed by plastic or rubber process, and have been successfully transplanted into calended-forming permanent magnets. The most popular one is chlorinated polyethylene elastomer, which can be used to make high filling ratio bonded magnets. And the traditional vulcanization process of rubber can be omitted. The biggest disadvantage of thermoplastic elastomers is that they are inferior to rubber in terms of wear resistance and temperature resistance, but the wear resistance requirement is not very prominent for most permanent magnet applications.
