Transparent, autoclavable, non-cytotoxic, essentially compact polyurethane embedding compositions, the preparation thereof and the use thereof, especially for articles used in medicine

A transparent, autoclavable, non-cytotoxic, essentially compact polyurethane embedding composition, prepared by reacting

• a) urethane group-containing diphenylmethane diisocyanates having an NCO content of from 29 to 15% by weight with
• b) compounds with at least two reactive hydrogens in the presence or absence of
• c) catalysts wherein component (b) is a mixture which contains
• b1) at least one polyether-polyol with an average functionality of from 3 to 8, a hydroxyl number of from 200 to 1000 and an alkali metal ion content of from 150 to 1200 ppm and
• b2) castor oil or at least one polyether-polyol with a functionality of from 2 to 3, a hydroxyl number of from 90 to 200 and an alkali metal ion content of less than 10 ppm or a mixture of castor oil and at least one of said polyether-polyols.

A process for preparing transparent, autoclavable, non-cytotoxic, essentially compact polyurethane embedding compositions by reacting

• a) urethane group-containing diphenylmethane diisocyanates having an NCO content of from 29 to 15% by weight with
• b) compounds with at least two reactive hydrogens in the presence or absence of
• c) catalysts wherein component (b) is a mixture which contains
• b1) at least one polyether-polyol with an average functionality of from 3 to 8, a hydroxyl number of from 200 to 1000 and an alkali metal ion content of from 150 to 1200 ppm and
• b2) castor oil or at least one polyether-polyol with a functionality of from 2 to 3, a hydroxyl number of from 90 to 200 and an alkali metal ion content of less than 10 ppm or a mixture of castor oil and at least one of said polyether-polyols