3A Composites, a material supplier based in Cham, Switzerland, has over 50 years of experience manufacturing structural core materials like closed cell foams, and balsa products. The company recently launched a new surface sealant for polyethylene terephthalate (PET or polyester) foam cores called AIREX SealX at the 2012 JEC Show in Paris. SealX reduces the amount of resin absorbed by the foam, thus significantly lowering the weight and cost of manufacturing composite sandwich parts in resin infusion processes.

According to Philipp Angst, director of product management at 3A Composites Core Materials, PET foams are well received in major core material markets like marine, wind energy and industrial because the material is easy to use and can produce composite parts at a high level of consistency. “Currently, the major problem with PET is that the resin uptake is higher than comparable polyvinyl chloride (PVC) foam, which limits its cost advantage in infusion applications,” says Angst.

Motivated to ease the problems associated with resin uptake, 3A Composites began developing technology to give its PET foam, AIREX T92, an advantage over competitive core materials like styrene acrylonitrile (SAN) or PVC. Compared to rival PET foam products, the resin saving of SealX can be even larger since these other PET foams have less optimized cell structure and exhibit higher resin uptake.

“We can now reduce the resin taken up by the core’s surfaces during infusion processes by about 50 percent, relative to our uncoated AIREX T92,” says Marc Anderson, director of sales and marketing at Baltek Inc., a subsidiary of 3A Composites. “The reduction in resin will reduce overall weight and fabrication costs of the end product, two targets that are very high priorities for our customers.”

There were several obstacles the company had to overcome in order to pioneer the surface sealant market. For example, there weren’t many technology demonstrators to help develop the initial product. “We had to build new equipment since the expertise to produce SealX simply didn’t exist. Basically, we had to start from scratch,” says Angst.

Another obstacle for the company was to find the optimum balance between minimum resin uptake and good core-skin adhesion. Using patented technology, researchers at 3A Composites ensured SealX will maintain the skin adhesion and fatigue properties of PET and prevent resin uptake, resulting in the same chemical bond between core and skin using less resin.

In addition to the new PET products, 3A Composites will launch a similar SealX surface sealant for its BALTEK balsa product line into the marketplace by the end of 2012. Research conducted by 3A Composites suggests SealX reduces resin uptake in balsa core by approximately 80 percent and composite weight by 35 percent. The company predicts that the new balsa surface sealant could significantly curb the weight and cost of balsa sandwich panels.