Siloxane Masterbatch MB25-302

Processing additive to improve surface characteristics in resin-compatable systems.

Dow Corning® Functionalized Ultra High Molecular Weight Siloxane Masterbatches are pelletized formulations containing 25 and 50 percent of a functionalized ultra-highmolecular-weight (UHMW) siloxane polymer. They are designed to be used as additives in resin-compatible systems to improve processing and modify surface characteristics.

Silicone-based plastic additives have been used in the plastics industry for several years to improve the mold release and flow of thermoplastics. They are effective in this role, although some difficulties have been experienced in the accurate incorporation of low-viscosity liquids into thermoplastic melts without use of specialized equipment. The Dow Corning Functionalized Ultra High Molecular Weight Siloxane Masterbatches address this problem by supplying an ultrahigh-molecular-weight siloxane as a dispersion in a dry pellet form in a variety of thermoplastics. The siloxane is finely dispersed in the thermoplastic matrix as the discrete or discontinuous phase at an average particle size of less than 5 microns.

BENEFITS
Dow Corning Functionalized Ultra High Molecular Weight Siloxane Masterbatches offer a patented surface segregation functionality that facilitates a higher concentration of the siloxane toward the surface of a fabricated part, thus providing improved surface benefits. Siloxane moves to the surface only when the thermoplastic is in the melt phase, remaining in discrete domains in solidified thermoplastic, unlike low molecular weight fluids that migrate. Lower levels of additive are required for surface modification because more is being utilized at the surface, rather than being trapped internally.

The functionalized siloxane has unique advantages over standard polydimethylsiloxane. The UHMW siloxane demonstrates superior slip performance in polyolefin films and, because the functional groups provide attraction to the metal surface, metal fracture is reduced during polymer processing.

Because of the coefficient of friction (COF) stability, immediate slip measurement is possible. Moreover, the COF remains consistent at high line speeds and during hot packaging applications that generate high film surface temperatures on form-fill-seal equipment.

When added to resin-compatible systems at 0.1 to 1 percent siloxane, these products offer reduced melt fracture, better mold filling, lower extruder torque, internal mold lubrication, mold release and reduced warpage of the molded part.

At higher siloxane loading levels, 1 to 5 percent siloxane, enhanced surface properties are expected, including enhanced lubricity and slip, lower coefficient of friction and improved mar resistance.

LIMITATIONS
These products are neither tested nor represented as suitable for medical or pharmaceutical uses.

HOW TO USE
Dow Corning Functionalized Ultra High Molecular Weight Siloxane Masterbatches may be processed at the same conditions as the thermoplastics on which they are based. Sufficient Dow Corning Functionalized Ultra High Molecular Weight Siloxane Masterbatch should be blended with virgin polymer pellets to give the desired siloxane level in the final product. Dow Corning Functionalized Ultra High Molecular Weight Siloxane Masterbatch can be added during compounding in an extruder or dry blended at the feed hopper during injection molding, profile/sheet extrusion or other conventional thermoplastic processes.