Fiber composite component and a process for the production thereof

Abstract

The present invention relates to sheet-form fiber composite components which are obtainable by impregnating fibers with a reactive resin mixture comprising polyisocyanates, polyepoxides, polyols and optionally additives, and to a process for the production thereof.

Claims

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.

Description

EXAMPLES

(1) Fibre-reinforced moulded articles were produced from the polyurethane systems according to the invention comprising polyisocyanates, polyols and polyepoxides and were compared with a polyurethane system comprising polyisocyanate and polyol. For the production of the fibre-reinforced moulded article by vacuum infusion, a Teflon tube having a diameter of 6 mm was filled with glass fibre rovings (Vetrotex® EC2400 P207) so that a glass fibre content of about 65 wt. %, based on the later component, was achieved. One side of the Teflon tube was immersed in the reaction mixture, and vacuum was generated on the other side with an oil pump and the reaction mixture was thereby drawn in. After the tubes were filled, they were tempered overnight at 80° C. The Teflon tube was removed. Mechanical measurements were carried out on the fibre-reinforced test specimens. The glass fibre content was determined by calcination of the test specimens according to DIN EN ISO 1172. The bending strength and bending elongation were determined by means of a 3-point bending test according to ISO 3597-2.

(2) The viscosity was determined immediately after mixing and 60 minutes after mixing of the components using a rotary viscometer at 35° C. with a shear rate of 60 l/s.

(3) The NCO/OH equivalent ratio gives the ratio of the number of NCO groups in the polyisocyanate component A) to the number of OH groups in the polyol component B).

(4) The NCO/EP equivalent ratio gives the ratio of the number of NCO groups in the polyisocyanate component A) to the number of epoxide groups in the polyepoxide component C).

Example 1

(5) 48 g of a polyether polyol having an OH number of 380 mg KOH/g and a functionality of 3 (viscosity at 25° C.: 600±50 mPas; trimethylolpropane as starter; propylene oxide-based) were mixed with 12 g of Eurepox® 710 (bisphenol A epichlorohydrin resin having an average molecular weight ≦700 g/mol; epoxide equivalent 183-189 g/eq; viscosity at 25° C.: 10,000-12,000 mPas) and degassed for 60 minutes at a pressure of 1 mbar. 55.76 g of Desmodur® VP.PU 60RE11 (polyisocyanate from Bayer MaterialScience AG; mixture of diphenylmethane diisocyanate and polyphenylenepolymethylene polyisocyanate; NCO content 32.6 wt. %; viscosity at 25° C.: 20 mPas) were then added, and degassing was carried out for 5 minutes at 1 mbar, with stirring. A fibre-reinforced moulded article was then produced by vacuum infusion using the reaction mixture.

Example 2

(6) 30 g of a polyether polyol having an OH number of 380 mg KOH/g and a functionality of 3 (viscosity at 25° C.: 600±50 mPas; trimethylolpropane as starter; propylene oxide-based) were mixed with 30 g of Eurepox® 710 (bisphenol A epichlorohydrin resin having an average molecular weight ≦700 g/mol; epoxide equivalent 183-189 g/eq; viscosity at 25° C.: 10,000-12,000 mPas) and degassed for 60 minutes at a pressure of 1 mbar. 53.03 g of Desmodur® VP.PU 60RE11 (polyisocyanate from Bayer MaterialScience AG; mixture of diphenylmethane diisocyanate and polyphenylenepolymethylene polyisocyanate; NCO content 32.6 wt. %; viscosity at 25° C.: 20 mPas) were then added, and degassing was carried out for 5 minutes at 1 mbar, with stirring. A fibre-reinforced moulded article was then produced by vacuum infusion using the reaction mixture.

Comparison Example 3

(7) 60.7 g of a polyether polyol having an OH number of 380 mg KOH/g and a functionality of 3 (viscosity at 25° C.: 600±50 mPas; trimethylolpropane as starter; propylene oxide-based) were degassed for 60 minutes at a pressure of 1 mbar. 58.25 g of Desmodur® VP.PU 60RE11 (polyisocyanate from Bayer MaterialScience AG; mixture of diphenylmethane diisocyanate and polyphenylenepolymethylene polyisocyanate; NCO content 32.6 wt. %; viscosity at 25° C.: 20 mPas) were then added, and degassing was carried out for 5 minutes at 1 mbar, with stirring. A fibre-reinforced moulded article was then produced by vacuum infusion using the reaction mixture.

(8) TABLE-US-00001 Examples 1 2 3* NCO/OH equivalent 1.33 2.03 1.1 ratio NCO/epoxide equivalent 3.22 1.22 0 ratio Viscosity (immediately 84 95 74 after mixing) [mPas] Viscosity (60 min after 4980 2070 7190 mixing) [mPas] Mixing time at 40° C. 20 20 45 [sec.] Glass fibre content 64.3 63.0 65.1 [wt. %] Bending strength [MPa] 837.7 862.1 823.9 according to ISO 3597-2 Bending elongation [%] 2.80 3.04 2.69 according to ISO 3597-2 Interlaminar shear 43.66 44.13 42.22 strength (ShortBeam) [MPa] according to ISO 3597-4 *comparison