NCO-modified polyoxymethylene block copolymers
View Patent ↗The invention relates to a method for producing NCO-modified polyoxymethylene block copolymers comprising the step of polymerizing formaldehyde in a reaction vessel in the presence of a catalyst, the polymerization of formaldehyde in addition taking place in the presence of a starter compound comprising at least 2 Zerewitinoff active H atoms to obtain an intermediate product. The intermediate product obtained is reacted further with an isocyanate to obtain an NCO-modified polyoxymethylene block copolymer. The invention also relates to NCO-modified polyoxymethylene block copolymers obtained by a method of this type and to the use of said copolymers for producing polyurethane polymers.
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.
2. The process as claimed in claim 1 , wherein the starter compound has a number-average molecular weight of ≧100 g/mol to ≦3000 g/mol.
3. The process as claimed in claim 1 , wherein the starter compound is an oligomeric compound.
4. The process as claimed in claim 1 , wherein the starter compound is selected from the group consisting of polyether polyols, polyester polyols, polyether ester polyols, polycarbonate polyols, polyacrylate polyols, and combinations thereof.
5. The process as claimed in claim 1 , wherein the isocyanate is an aliphatic or aromatic di- or polyisocyanate.
6. The process as claimed in claim 1 , wherein the polymerization is additionally effected in the presence of a comonomer.