Thermoplastic polyurethane blends with improved properties - are prepd. by compounding thermoplastic polyurethane with a polyester and small amts. of organic di;isocyanate

摘要

Thermoplastic moulding materials (I) with increased strength and elastic modulus and improved thermal dimensional stability are claimed, contg. (A) 99.5-60 wt.% thermoplastic polyurethane elastomer (TPU) and (B) 0.5-40 wt.% other polymer, the novelty is that (B) is a polyester, and (I) also contains (C) 0.05-5 wt.% organic isocyanate esp. a diisocyanate. Also claimed is a process for the prodn. of (I) by blending (A) with amts. of (B) and (C) as above. Amt. of (C) is 0.1-3 wt.%, (A) is a polyester- and/or polyether-urethane based on long-chain OH cpds. with mol. wt. 500-3000, short-chain aliphatic and/or aromatic diols with mol. wt. below 600, aliphatic and/or aromatic diisocyanates and opt. stabilisers, etc., (B) is a homo- and/or copolymer and/or a blend based on linear thermoplastic polyester, pref. polyalkylene terephthalate, polycarbonate or polyethylene terephthalate/p-hydroxybenzoic acid copolymer, (c) is an aliphatic and/or aromatic diisocyanate and/or diiisocyanate- releasing cpd. and/or NCO-terminated prepolymer with mol. wt. below 500 contg. 0-60 wt.% higher-functional isocyanate, (C) is introduced into the compounding process together with (A) and/or (B) as a premix or separately via the same inlet, pref. (C) is added as a liq. or solid, in the direction of processing after adding (A), compounding temp. is 180-250 (pref. 210-240) deg.C. USE/ADVANTAGE - The invention provides TPU-based moulding materials with the above combination of improved properties, this is achieved by chemical reaction between terminal OH and COOH gps. in (B) and the diisocyanate (C) dissolved in (A), component (B) softens even at the low compounding temps. used, thus minimising thermal degradation of (A)