| abstract |
A reaction mixture is prepared by mixing a) an isocyanate, b) a compound having a group reactive to isocyanate, c) a blowing agent containing water, d) a catalyst, and e) further additives as necessary. , A rigid polyurethane foam obtained by applying a reaction mixture to a reinforcing material and curing the compound, wherein the isocyanate (a) has a viscosity of 500 mPas or less at 25 ° C. and has a group reactive to isocyanate (B) is a polyetherol (b1) having a functional group number of 4 or more and a viscosity at 25 ° C. of 10,000 mPas or less, and a polyetherol (b2) having a functional group number of 3.5 or less and a viscosity at 25 ° C. of 600 mPas or less. Polyesterol (b3) having a viscosity at 25 ° C. of 2000 mPas or less, chain extension containing at least 30% secondary OH groups (B4) and rigid polyurethane foam which comprises a crosslinking agent (b5) if necessary. [Selection figure] None |