Siloxane Masterbatch  MB50-008 - Multibase, A Dow Corning Company - 

Ultra-high molecular weight siloxane polymer dispersed in styrene-acrylontrile-combatible systems.

DOW CORNING MB50-008 Masterbatch is a pelletized formulation containing 50% of an ultra-high molecular weight siloxane polymer dispersed in styreneacrylonitrile (SAN) carrier. It is designed to be used as an additive in most styrenic-compatible systems to impart benefits such as processing improvements and modification of surface characteristics.

Liquid siloxane plastic additives have been used for several years to improve the lubricity and flow of thermoplastics. They are effective in this role although some difficulties have been experienced in the incorporation of liquids into thermoplastic melts without the use of specialized equipment. It has also been difficult to produce masterbatches with greater than 20% liquid siloxane because of processing difficulty and bleed problems.

The DOW CORNING® MB Series Masterbatches address these problems by supplying a high concentration of an ultra-high molecular weight siloxane as a dispersion in a dry pellet form in a variety of thermoplastics.

BENEFITS
When added to SAN or similar thermoplastics at 0.1% to 1.0%, improved processing and flow of the resin is expected, including better mold filling, less extruder torque, internal lubrication, mold release and faster throughput. At higher addition levels, 1% to 5% siloxane, improved surface properties are expected, including lubricity, slip, lower coefficient of friction, and greater mar and abrasion resistance.

The DOW CORNING MB Series Masterbatches are expected to give improved benefits compared to conventional lower molecular weight siloxane additives, e.g., less screw slippage, improved release, a lower coefficient of friction, fewer paint and printing problems, and a broader range of performance capabilities. The addition of 2% polydimethylsiloxane gives a significant reduction in wear rate. While this data was obtained with a lower molecular weight siloxane additive, similar results are expected when DOW CORNING MB50-008 Masterbatch is added to styrenics (SAN, ABS, polystyrene). Additionally, use of ultra-high molecular weight siloxane additives give very little loss in paintability with a waterborne paint system.

LIMITATIONS
This product is neither tested nor represented as suitable for medical or pharmaceutical uses.

HOW TO USE
DOW CORNING MB Series Masterbatches may be processed in the same way as the thermoplastics on which they are based. Sufficient DOW CORNING MB50-008 Masterbatch should be blended with virgin polymer pellets to give the desired siloxane level in the final product. DOW CORNING MB50-008 Masterbatch pellets can be added during compounding in a single screw extruder or added at the feed hopper during injection molding or extrusion.