A family of patent-pending p polyu olyurethane d rethane dispersions (PUD) with high m ispersions moisture v oisture vapor t apor transmission r ransmission rates (MVTR) has been developed by Noveon, Inc. (formerly BFGoodrich Co.). These dispersions allow one to produce coatings with MVT rates ranging from 500 (ASTM E-96 upright water cup method) to as high as 1,000+ gram/sq. meter/day. These polymers rely on the diffusion of moisture through a monolithic film, rather than a microporous membrane, and thus provide better protection against hazards such as chemical vapors, biological agents, etc. Other benefits include: ? virtually zero VOC (v ates volatile o olatile organic c rganic compound) ? wide formulating latitude for tailoring both soft (quiet) and hard products ? exceptional tolerance to compounding ingredients of any nature ? crosslinkability ? color retention after UV exposure. ? Several commercially available products have been developed which give high MVT properties, and optionally a hydrophobic film which beads up water. Permax? polymers are offered in the form of water dispersions and can be processed on existing production lines without any major adjustments.
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