Patent ID: 9534090
Date: 2017-01-03
CPC Classifications: C08G

Claim:
1. A process for preparing NCO-modified polyoxymethylene block copolymers, comprising the step of polymerizing gaseous formaldehyde in the presence of a catalyst selected from the group consisting of basic catalysts, Lewis-acidic catalysts, and combinations thereof, to form a polyoxymethylene block copolymer intermediate, wherein the polymerization of formaldehyde is effected in the presence of a starter compound having at least two Zerewitinoff-active hydrogen atoms, giving an intermediate having a number-average molecular weight of <4500 g/mol, and reacting the intermediate with an isocyanate in the presence of a catalyst which is the same catalyst as in the preceding polymerization of formaldehyde, to give an NCO-modified polyoxymethylene block copolymer.