| 摘要 |
<p>A relatively inexpensive injection molding-grade thermoplastic polyurethane elastomer is based on a modified polyether diol--a modified polypropylene glycol (PPG) ether. This elastomer has improved toughness, abrasion resistance and general good mechanical properties. Its temperature insensitivity and low temperature flexibility are exceptional. It is flexible to impact at -50.degree.F and stiff enough at 250.degree.F to allow painting without distortion. Of special interest is the fact that this polymer is injection moldable and possesses properties adequate for exterior automobile trim components and the like. The polyether polyol is a poly (oxyalkylene) diol reacted with a 50/50 styrene/acrylonitrile monomer mixture in the presence of a free radical catalyst. While a one shot method of preparation can be used, the capped polyol is preferably reacted with an aromatic diisocyanate to form a prepolymer in a known manner. The prepolymer is thereafter reacted with a C2 to C6 alkane diol, pan cast, cured and aged, followed by grinding to give the molding composition. It is preferred to blend the polyol with a minor amount of a poly alkane ether diol prior to forming the prepolymer as this enhances the moldability and properties of the thermoplastic polyurethane.</p> |
