The Balsaflex UVOTEC technology can be used in hand lay-up, vacuum bag and infusion processes.
As Dr Damian Bannister, Gurit’s Chief Technology Officer, explains, balsa wood contains a number of vessels and cells, some of which go all the way through the wood. This means a balsa panel can absorb 2 kg plus of resin per side, per square metre. So Gurit looked at ways of sealing the balsa surface, while adding as little weight as possible.
Bannister reports that with the UVOTEC coating a reduction in resin absorption of roughly 1-1.3 kg/m2 is being seen.
This was proven in tests on a sandwich laminate constructed with two plies of 1200 g/m2 triaxial glass each side of a Balsaflex 150 core, with and without UVOTEC coating, infused with Gurit's PRIME 20 LV epoxy infusion resin to achieve 35% resin content laminates.
This reduction in resin absorption reduces the weight of the panel, and reduces the amount of resin used, resulting in cost savings.
Adhesion performance
"The other problem you have when you seal products is that you can reduce the mechanical bond with the laminate," notes Bannister, "so the target here was to have a product that still had very good peel strength to the laminate."
Gurit performed numerous adhesion tests which demonstrated no detriment to the adhesion strength of UVOTEC-coated balsa.
Wind energy
One application for the UVOTEC-coated balsa is wind energy.
"A lot more of the wind blades now are getting more weight critical, so obviously saving a kilo per square metre’s beneficial, but also you save however much you’re paying for your resin as well," notes Bannister.
"So there is a premium for the sealing technology, but at the same time it saves you more on the resin, so it’s more about weight reduction."
Balsaflex balsa core material is also used in marine, automotive, truck, rail and aircraft parts.
The UVOTEC coating is currently available on plain sheet.
- Gurit acquired Spanish balsa material producer Balseurop, manufacturer of Balsaflex brand balsa core material, for approximately €20 million in 2011. (See Gurit acquires balsa producer Balseurop.)
COMMENT
In 2012, 3A Composites Core Materials introduced a surface sealing technology for its polyethylene terephthalate (PET) foam core materials which considerably reduces their resin uptake. (See Redesigning the core materials landscape.)
