| 摘要 |
PURPOSE: Multistage continuous production of thermoplastically-processable polyurethane elastomers(TPU) with EN ISO 527-3 tensile strength above 30 MPa is provided which involves catalytic reaction of an organic polyisocyanate with a first polyol, followed by reaction of the resulting prepolymer with a second polyol, the resulting prepolymer then being reacted in a high-shear high-viscosity reactor with a low molecular polyol chain-extender. CONSTITUTION: The continuous production of thermoplastically-processable polyurethane elastomers(TPU) with EN ISO 527-3 tensile strength above 30 MPa comprises the steps of (a) reacting an organic polyisocyanate with a polyol (I) with 1.8-3 Zerewitinoff hydrogens and average Mn 450-10,000; (b) reacting the resulting prepolymer with a different polyol (II) with 1.8-3 Zerewitinoff hydrogens and average Mn 60-10,000, the polyisocyanate, (I) and (II) having an NCO : reactive groups equivalent ratio of 1.2-10 : 1; and (c) completely reacting this resulting prepolymer in a high-shear high-viscosity reactor with a low molecular polyol (III) chain-extender with 1.8-3 Zerewitinoff hydrogens and average Mn 60-400, the steps (a) - (c) being in presence of a catalyst and optionally also 0-20 wt.% (based on the TPU) additives and the overall equivalent ratio NCO : reactive groups in steps (a) - (c) being 0.9-1.2 : 1.
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