A chemical reinforcing agent introduced three years ago by Milliken (Spartanburg, SC) is about to debut on production cars, Adam Watson, global product line manager for Hyperform HPR reinforcing agents, told The Molding Blog in an interview.
Hyperform HPR-803i is being used to replace talc fillers in polypropylene and thermoplastic olefin (TPO) compounds as a way to reduce weight and improve surface quality, scratch performance and color. Stiffness and heat deflection temperature are also improved, Watson said.
Typical loadings are in the 3-10% range and the additive is often used with talc, but at reduced amounts. “It is a crystalline whisker that we grow in a chemical reaction that has an aspect ratio of 20 or 30 to one,” Watson said in the interview. “You introduce it like talc or chopped glass or one of the natural fillers that are being looked at.”
Milliken is working on polypropylene and TPO applications now.
“We’re very focused on automotive and polypropylene is a growth plastic in the automotive area,” Watson said. “Hyperform HPR-803i also works well in polyethylene, but there aren’t as many applications (for PE in automotive) where you need the stiffness.” The focus on PP also fits well with Milliken’s work on clarifying and nucleating agents.
Milliken also plans to test the material in variety of other thermoplastic and thermoset materials that use fillers and could be light weighted.
Milliken thinks that at least for the short-term, Hyperform HPR-803i will be blended with talc, which is the primary filler used in automotive. Talc has excellent physical properties, but has a high density, boosting part weight. As a blend, Hyperform HPR-803i can leverage the benefits of talc, while reducing weight of large parts such as bumpers, fascia, door trim, grilles, and instrument panels.
“You can get the advantages of talc, Hyperform HPR-803i and still get a lower density,” Watson. “In my mind, in the longer term Hyperform HPR-803i will be used in higher percentages to offer more weight reduction.”
Hyperform HPR-803i costs more than talc, but can reduce total system costs, according to Milliken.
Like any filler, Hyperform HPR-803i has some effect on processing conditions. “I’d like to say it’s a drop-in, but with all fillers you have to be aware of shrinkage and orientation. The processors have figured out how to make this work. That’s what these companies are really good at.”
Watson said that Hyperform HPR-803i is in the early stages of qualification by several major global companies. One is close to mass production. Specifics were not available.
One company that has gone public concerning its use of Milliken’s novel reinforcing agent is French automotive component producer Mecaplast.
It has produced a TPO compound containing a mix of talc and Hyperform HPR-803i (total additive content around 10% by weight) to mold prototype B-pillar covers that it normally supplies in a conventional 20% talc-filled TPO (elastomer-modified polypropylene). The prototype parts weighed 7% less than the commercial parts. The compound has a density of 0.98 g/cm3, which compares with 1.04 g/cm3 for a 20% talc-filled TPO with similar mechanical properties.
The compound is produced by Inno-Comp in Hungary.