LEARN MORE

Related Suppliers

Dow Automotive

Zones



A Revolutionary Material

This is a technology that can change the industry.

  That’s Jean Palmieri, new business development manager for Dow Automotive (Auburn Hills, MI), talking about the cyclic form of polybutylene terephthalate (CBT) resins. Cyclics Corp. (Schenectady, NY), the company that has developed the material (actually, it bought the patents on various cyclic compositions from GE in 1999, and has been subsequently working on developments), and Dow Automotive have entered into a marketing agreement wherein Dow Automotive is going to be handling the auto, bus, truck, and rail markets for the plastics.

And when she’s talking about this change, she just doesn’t mean the plastics industry. She’s talking about automotive. While there are, at present, no commercial applications of this new material in any industry, as she describes it, it becomes quite likely that, as she puts it, “the floodgates will open” once there is a wide spread understanding of what it can mean.

Like Water vs. Molasses. OK. “Change the industry” is a bit much. Until you comprehend just what the CBT resins actually mean with regard to process and product. Especially process. When this material melts (it comes in powder, pellet, and flake forms), it has a low viscosity. Palmieri describes this as being “like water.” By way of contrast, she points out that other thermoplastic materials, when melted, for, say, creating a glass-filled composite material, have a viscosity “like molasses.” The CBT flows. It is consequently capable of moving through molds at comparatively low pressure. She points out that, for example, if one is trying to make a glass-mat-based composite with the typical resin, the viscous nature of the material will cause it to get bound up in the mat and to even push it to places that are not necessarily desirable. That is not a problem with the CBT. There is said to be excellent wet-out and the ability to have high filler content. (Polymerization of the material is based on the use of a catalyst.)

Essentially, the CBT has a low viscosity like a thermoset material, but it is a thermoplastic. Because of this dual nature, the material can be used in processes including (but not limited to): compression molding, injection molding, extrusion, resin transfer molding, and reactive injection molding. Apparently, there’s no need for substantial equipment or tooling changes to occur when the CBT is used. In fact, Palmieri notes that because of the reduced pressure involved in molding because of the low viscosity, smaller machines can be used to make parts. After parts are produced, they can be welded, bonded and painted. And they’re recyclable (e.g., back to base chemicals or reground for use as molding compound or as a filler for one). There’s no styrene, so it is environmentally friendly from that point of view, as well.

Panel Production. There’s another aspect to the processing with CBT that Palmieri notes: it has a comparatively quick cycle time. Which leads her to where she thinks the material will really matter in automotive applications: body panels. She acknowledges that for the most part, there are longer cycle times associated with making large plastic panels. That has had the effect of keeping volumes low, perhaps (typically) no more than 75,000 units and as few as 5,000. But she says that CBT will make it possible to economically compete with volumes in excess of 150,000 units. She describes injection molding fenders and quarter panels “with 3D geometries that aren’t limited by compression molding constraints.” She talks about how CBT can be loaded with material so that it has the toughness, stiffness, and high heat resistance necessary to be used to produce hoods, deck lids, and roofs. Surface finish? “We’ve demonstrated Class A,” she replies. Because of the compatibility with so many filler materials, she points out that the initial application will be Class B (e.g., truck box components) or non-Class A (e.g., load floors and bumper beams). “We think this will expand the thermoplastic market,” she says.

Plastics producers have long talked about the advantage of comparatively lower tooling costs for plastic parts as compared with the costs required for steel or aluminum parts. Palmieri makes the same argument, but is able to point out that the advantages provided by the lower viscosity makes a tremendous difference especially as it relates to the equipment required to make larger parts. Then, she goes on to explain, there are advantages that are based on part characteristics, such as the modulus stiffness, formability, processability, and weight (i.e., you can form shapes with plastics that are difficult—perhaps impossible—to attain with metal, so add to the mix the ability to make these shapes that are strong and light and to do so quickly, and the plastics vs. metal argument takes on a whole new aspect).

As there are no commercial parts yet, and as the plant that will be producing the CBT materials won’t come on line until mid-2004, chances are this potential revolution won’t occur in automotive for a few years. But once started, it could make tremendous changes: think of niche vehicles with their own subniches.