Title: Polyurethane prepared by reaction of an organic polyisocyanate, a chain extender and an isocyanate-reactive material of m.w. 500-20,000 characterized by the use of only 2-25 percent by weight of the latter material

 Number/Link: US4376834

Applicant/Assignee: Upjohn

Publication date: 15-03-1983

“Gist”: Very high hardblock TPU from MDI and chain extenders.

Why it is interesting: “Isoplast” is a so-called engineering thermoplastic useful in niche applications where high impact strength and high chemical resistance are required. The material can be clear or reinforced and can also be used in fiber-reinforced composites.  Currently the trademark is owned by Lubrizol who acquired it from Dow who in turn bought it from Upjohn in the 1980s.  Isoplast is made from 4,4′ MDI and a mixture of chain extenders selected from MEG,DEG, neopentyl glycol, 1,4-cyclohexanedimethanol etc. The choice of chain extenders controls the crystallinity/glassiness of the polymer.  A few percent of high mole weight polyol may be added to improve impact resistance. A very interesting material with interesting melt-flow characteristics because of its depolymerization and repolymerization behaviour during processing.

Screw from reinforced Isoplast