Promising to, “Take you on journey of how to foam without release agent,” Frimo’s Dr-Ing Florian Meyer described a joint project with Kunststofftechnik Wiesmayer GmbH to develop a thermoplastic mould liner, called PURe Liner.
The aim is to eliminate the need to apply mould-release agents with reactive materials such as polyurethane and epoxy.
Release agents are a great bugbear in moulding PU but, as Meyer explained, “We need release agents because reactive plastics have a strong adhesion to steel.”
Release agents can be a semi-permanent layer, but many are waxes which must be applied before every shot and, “you get residues which have to be cleaned.” Recently, permanent treatments have been developed: “We have heard of miracle layers, and some are good solutions,” said Meyer, noting that plasma polymer layers work well, but can be costly.
Release-agent residue can also be difficult to remove completely from the components, causing problems for parts which have to be glued.
“While I think some release agents are able to offer solutions to these problems, costs, both one-time and recurrent costs, are high,” Meyer stressed.
Costs include that of the wax, of maintenance/ cleaning of the mould, of mould-spraying equipment, and also of ventilating the spraying area to protect workers, and remove any solvent.
PURe Liner is an injection-moulded plastic, which is a self-separating compound, which Frimo has evaluated in front-foaming, to…