Gas-permeable material with excellent compatibility with blood

A gas-permeable material compatible with blood produced by steps comprising:

• preparing polyurethane or polyurethaneurea from reactants comprising diisocyanate, polysiloxane containing terminal hydroxyl groups or polysiloxane containing terminal amino groups, and polyesterpolyol containing an aminediol of formula IIb with dicarboxylic acid as a main component thereof, polyetherpolyol obtained by the condensation of aminediol of formula IIc or polyamide polyamine containing aminodiamine of formula Vb with dicarboxylic acid as a main component thereof:
• ##STR9## wherein R.sub.4 is a hydrogen atom or an alkyl group containing 1-5 carbon atoms, R.sub.5 is an alkyl group containing 1-20 carbon atoms, and R.sub.13 and R.sub.14 each independently is an alkyl group containing 1-10 carbon atoms;
• converting tertiary amino groups contained in the polyurethane or the polyurethaneurea to quaternary ammonium groups;
• and
• treating the polyurethane or the polyurethaneurea having quaternary ammonium groups with heparin;
• wherein the proportion by weight of the polysiloxane in the resulting polyurethane or polyurethaneurea is 30-85%, the amount of tertiary amino groups in molecules included in the resulting polyurethane or polyurethaneurea is at a proportion of 0.05-2.00 mmol/g, and the molecular weights of the polyesterpolyol, polyetherpolyol and polyamide polyamine are 500-8000.