Fiber composite component and a process for the production thereof

1. A sheet-form fibre composite component prepared by the vacuum-assisted resin transfer moulding process, for use in the production of rotor blades of wind turbines, comprising a fibre layer impregnated with polyurethane, wherein the polyurethane is obtainable from a reaction mixture comprising

A) one or more polyisocyanates;

B) one or more polyether polyols comprising an addition product of propylene oxide on a di-functional or poly-functional starter molecule, the polyether polyol(s) comprising at least 80% secondary OH groups;

C) one or more polyepoxides; and

D) optionally additives,

wherein the reaction mixture has a viscosity at 35° C. of from 50 to 250 mPa and a ratio of the number of NCO groups to the number of OH groups of component B) of from 1.3:1 to 10:1 and a ratio of the number of NCO groups to the number of epoxide groups of component C) of from 1.1:1 to 10:1, and

wherein the one or more polyisocyanates consists of mixtures of diphenylmethane diisocyanate and polyphenylenepolymethylene polyisocyanate with a monomer content of from 70 to 95 wt. % in the polyisocyanate component of A) based on the total weight of the polyisocyanate components.

2. The sheet-form fibre composite component of claim 1 , wherein one or more gelcoat layers are present on one side of the polyurethane-containing fibre layer.

3. The sheet-form fibre composite component of claim 2 , wherein a spacer layer is present on the side of the polyurethane-containing fibre layer that is remote from the gelcoat layer, which spacer layer is followed by a further polyurethane-containing fibre layer.

4. The sheet-form fibre composite component of claim 1 , wherein a spacer layer is present on one side of the polyurethane-containing fibre layer, which spacer layer is followed by a further polyurethane-containing fibre layer.

5. A process for producing the sheet-form fibre composite component of claim 1 by the vacuum-assisted resin transfer moulding process, comprising

a) preparing a mixture of

A) one or more polyisocyanate;

B) one or more polyether polyols comprising an addition product of propylene oxide on a di-functional or poly-functional starter molecule, the polyether polyol(s) comprising at least 80% secondary OH groups;

C) one or more polyepoxides; and

D) optionally additives,

wherein the mixture has a viscosity at 35° C. of from 50 to 250 mPa and a ratio of the number of NCO groups to the number of OH groups of component B) of from 1.3:1 to 10:1 and a ratio of the number of NCO groups to the number of epoxide groups of component C) of from 1.1:1 to 10:1, and wherein the one or more polyisocyanates consists of mixtures of diphenylmethane diisocyanate and polyphenylenepolymethylene polyisocyanate with a monomer content of from 70 to 95 wt. % in the polyisocyanate component of A) based on the total weight of the polyisocyanate components;

b) laying a fibre material in a mould half;

c) introducing the mixture prepared in step a) into the fibre material of step b) to produce an impregnated fibre material; and

d) curing the impregnated fibre material at a temperature of from 20 to 120° C.

6. The process of claim 5 , wherein step d) is performed at a temperature of from 70 to 90° C.

7. The process of claim 5 , wherein before step b), b′) one or more gelcoat layers are introduced into the mould half.

8. The process of claim 5 , wherein after step b) and before step c) a spacer material layer and then a fibre material layer are introduced into the mould half.

9. A rotor blade for wind turbines, a bodywork component for motor vehicles, an aircraft, a building, a road, or a structure which is subjected to high stress comprising the sheet-form fibre composite component of claim 1 .