Filtering polymer with metal powder
The Challenge – Ensuring optimum cleaning during filtration
Hot polymer filtration is the process used to clean liquid polymer before it is spun into fine synthetic fibres, such as nylon and polyester. The filtration takes place in a spin pack and several filter mediums – including glass beads, mineral sand and metallic fibres – can be used. But all of these materials have their disadvantages – glass and sand tend to crack under high pressure, forming fine particles that clog the holes during filtration, and metal fibres offer a low porosity level, making them less effective at removing impurities.
The Solution – Combating clogging and cracking to improve fibre quality
As specialists in this complex field, Höganäs is today one of the world's largest suppliers of filtration material for the textile industry. This is because the particles of our metal powder have a large active area and a highly irregular shape, ensuring optimum cleaning during filtration. The production method for our special metal powder is based on tried-and-tested high-pressure water atomization. A liquid metal stream is shattered by water jets into small particles, and that’s what gives them their unusual structure.
The chemical composition is also important for the particles’ strength. Iron is used as the base metal, but we also add alloying elements such as chromium, nickel, silicon and carbon to further improve durability and maintain high porosity throughout filtration. This minimizes the pressure increase – and – as the particles are not brittle, they do not crack during filtration.
The Result - Quality synthetic fibre that’s more cost-efficient
The risk of the nozzles clogging is eliminated. As the polymer passes through the spin pack, impurities and contaminants are removed thanks to the metal powder particles. High porosity and a large active surface area are also maintained throughout the filtration cycle. Using metal powder is therefore very cost effective. And – ultimately - the clothes you are wearing are better quality for it.