Automotive & anti-corrosion resins highlight SPI Composites Expo.

New automotive SMC resins based on recycled PET were plentiful at the SPI Composites Institute's 51st Annual Conference & Expo held recently in Cincinnati. Other new resins based on terephthalic acid - a key ingredient in PET - addressed the current shortage of isophthalic corrosion-resistant materials. Another new twist was the appearance of resins based on soybean protein as matrixes for composites.

Still other news in Part I of our report on the SPI meeting (Part II next month will cover new machinery) includes peroxide initiators, several glass reinforcements for pultrusion and RTM, and flame-retardant fillers and wetting agents for attaining higher filler loadings.

'GREEN' RESINS & ADDITIVES

Several suppliers sounded environmental themes with new products related to recycling, renewable raw materials, and reduced VOC emissions. There was growing evidence of a trend that first became apparent at last year's SPI show: Polyesters containing recycled PET - or terephthalic acid (TPA) derived from recycled and depolymerized PET - are moving into closed-mold applications after many years' use in open molding (see PT, April '95, p. 41). One particular motivation appears to be meeting automotive demands for recycled content. Resin suppliers say PET- or TPA-based polyesters have a thermoplastic-thermoset copolymer structure that can contribute higher strength, toughness, and flexibility.

One new recycled-content polyester resin for closed molding is P-460 from Alpha/Owens-Corning, Collierville, Tenn. It has a higher recyclate content and higher mechanical properties than AOC's first recycled-content resin for closed molding that was introduced a year ago. Based on TPA from reclaimed PET, P460 is aimed at SMC, BMC, cold molding, and pultrusion. According to AOC, P460 polyester also exhibits good weatherability and is being evaluated for applications that traditionally have gone to isophthalic polyester, which is in tight supply due to a worldwide shortage of isophthalic acid.

Several new recycle-content products were introduced by Ashland Chemical Co.'s Composite Polymers Div., Dublin, Ohio. One is a new class of SMC low-profile additive, described as a "polyester hybrid," that contains 25% post-consumer recycled PET. Envirez 2431 is said to be effective with a wide variety of resins and can provide Class A surfaces.