Silicone masterbatch for acetal, styrenic resins

Two new silicone additives in a dry masterbatch pellet form, MB40-006 and MB50-008, have been designed for use in acetal systems and styrenic resin systems respectively. MB40-006 is designed to lower the coefficient of friction and increase abrasion and wear resistance in severe-duty applications. The additive is a 40 percent dispersion of an ultra-high molecular weight silicone in an acetal copolymer.

The carrier resin used in the new masterbatch product is Celcon M270 acetal copolymer from Ticona, which has a melt flow index of 27. According to the manufacturer, the silicone masterbatch provides a variety of processing benefits, surface modification characteristics, and a broad range of performance capabilities compared with lower molecular weight silicone additives. At levels of .5 to 2.5 percent (.2 to 1.0 percent silicone) in acetal systems, the product offers faster throughput; better mold filling, internal lubrication, and mold release; and reduced molded part warpage. At higher levels of 2.5 to 12.5 percent (1 to 5 percent silicone), the silicone masterbatch can enhance the surface properties of acetal products such as plastic gears, pulleys, bushings, etc.

MB50-008 (application pictured) is designed to enhance lubricity and slip and abrasion resistance and to reduce the coefficient of friction. It is a 50 percent dispersion of an ultra-high molecular weight silicone in styrene-acrylonitrile (SAN) resin. The carrier resin used is Dow?s Tyril 100 SAN, which has a melt flow index of 8. It has the same benefits as MB40-006, but at .02 to 2.00 percent (.1 to 1.0 percent silicone). At higher levels of 2 to 10 percent (1 to 5 percent silicone), MB50-008 can provide improved surface properties in SAN and other styrenic resins.

The pelletized form of the silicone concentrates allows it to be blended with virgin or compounded acetal and styrenic resin pellets in order to attain the desired silicone level. The two silicone masterbatches come in 5-lb samples, 221-lb fiber packs, or in bulk. Cost is approximately $5/lb but varies depending on quantity.

Dow Corning Corp.
Midland, MI
Phone: (517) 496-6000