Development of cobalt-free accelerator

NPSP is helping Nouryon (formerly AkzoNobel) test cobalt-free accelerators. Under the European REACH legislation (Registration, Evaluation, Authorisation and Restriction of Chemicals), cobalt carboxylates such as cobalt octoate are evaluated by the European Chemicals Agency (ECHA). They have been classified by the Cobalt REACH Consortium as CMR2 Reprotoxic under CLP since August 2012 and may be reclassified as carcinogenic class 1B, which would restrict their use.

Cobalt octates are used as accelerators in the curing at ambient temperature of ¬unsaturated polyester and vinyl ester resins, where they activate the organic peroxide curing agents used. The free radicals formed help initiate the actual curing reaction. Today, the replacement of cobalt is one of the biggest challenges for the unsaturated polyester resin industry due to its extensive use. Most resins and applications are geared towards the use of this versatile metal.

Anticipating the increasing environmental pressure on cobalt, Nouryon is leading the way with a range of cobalt-free accelerators. The new Nouryact cobalt-free accelerators are based on copper, manganese and iron and can be used as an alternative to conventional cobalt-based accelerators. They are easy to use and can be mixed into a standard base resin at room temperature, making them suitable for all composite component manufacturers, end users and resin manufacturers.

NPSP was the first to test and evaluate Nouryact CF12 in its Resin Transfer Moulding (RTM) production process. Its evaluation shows that the cobalt-free curing system is a direct replacement for cobalt and that the process flexibility and mechanical properties of the final product are maintained.

NPSP manufactured the Pastoe Low LC03 composite chair with Nouryact CF12. The chair is manufactured under NPSP's Nabasco® label ('nature-based composites'), which guarantees that the production methods used are both environmentally friendly and technically and economically feasible. Moreover, the material is awaiting 'cradle to cradle' certification. The thickness of the component ranges from 4 mm to 8 mm and the reinforcements used are flax and hemp. The resin is a standard DCPD resin. The gel time is set to the desired 60 minutes. Curing is performed with Butanox M-50 at ambient temperature (20-23°C).

By using Nouryact, the composite world can take a step towards a material without the use of Critical Raw Materials.

Cobalt-free curing taking off - Materials Today