ASA alloys open up to auto opportunities

The alloying of amorphous styrene co-polymers and semicrystalline thermoplastics like polyamides (PA) and PBT creates materials with ideal properties for many applications in the automobile and electrical industries according to compounder Romira (Pinneberg, Germany). On account of their chemical composition and their ability to build crystalline structures, PA and PBT add the outstanding properties of enhanced stiffness, temperature and chemical resistance and excellent stress crack resistance to polymer blends with styrene polymers.

PBT/ASA alloy is already commercially employed in automotive trim

Glass fiber-reinforced semi-crystalline thermoplastics are known for their tendency to warp, a tendency which is significantly reduced by adding SAN or ASA. This combination guarantees a superior finish and enables application in various visible parts in the automobile and electrical industries. These properties are already being employed in the finishing of automotive trim using Romiloy PBT/ASA 5250 GF20. With eight to 30 per cent glass fiber or in combination with minerals, Romira offers a number of compound variations in its Romiloy 5240 series for injection molding applications.

Traditionally, most PBT/ASA applications are realized with reinforced compounds, where enhanced properties such as less warping, lower shrinkage and a higher quality finish are critical. But Romira also now offers a series of unreinforced PBT/ASA products (Romiloy 5240 and 5240/01) featuring minimal gloss and the ability to replicate various grained tool surfaces. The ASA component has also been added to these blends to realize increased UV and dimensional stability, a matt surface and increased impact resistance of the finished parts. The new series is comparable to the long-established Romiloy 3020 PA/ASA product group for unpainted parts in the automotive interior but is less sensitive to humidity, which further increases dimensional stability.-[email protected]