Preparation of polyurethanes

  • Inventors:
  • Assignees: Teijin Ltd
  • Publication Date: September 06, 1972
  • Publication Number: GB-1287691-A

Abstract

1287691 Coating TEIJIN Ltd 24 March 1970 [25 March 1969] 14343/70 Heading B2E [Also in Divisions B5 and C3] Substrates, particularly those of polyethylene terephthalate may be coated with a thermoplastic polyurethane prepared by reacting (A) a polyester which (a) has a crystalline m.p. of 150 to 220‹C, (b) two terminal OH groups, (c) is derived from terephthalic acid or a mixture of terephthalic acid and one or more other acids whose molar fraction in the mixture is Xa and from ethylene glycol or a mixture of ethlene glycol with one or more other glycols whose molar fraction in the mixture is Xg, the sum of Xa and Xg being at most 0.5; and (d) has a molecular weight (My) defined by the expression 2000 (Xa + Xg) + 400 # My # 6000 (Xa + Xg) + 800 and is in any case not more than 3000; with (B) an isocyanate terminated prepolymer obtained by reacting (1) a diisocyanate of formula OCN-R-NCO wherein R is an organic radical with (2) a diol of the formula HO-Z-OH wherein Z is an aliphatic polyether or aliphatic polyester residue, which compound has a m.p. at least 80‹C lower than the crystalline m.p. of the polyester (A) and has a molecular weight (M z ) which is defined by the expression 2000 (Xa + Xg) + 400 # M z # 3000 (Xa + Xg) + 1800. The polyurethane may be prepared in the melt or in a solvent. In example 5 polyester film and polyester taffeta were coated with a solution containing a thermoplastic polyurethane as defined above to produce articles which had excellent abrasion resistance and which could be high frequency welded.

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