Improvements in or relating to fibre reinforced composites

Patent metadata

Field	Value
Publication number	US-2016376399-A1
Application number	US-201414903303-A
Country	US
Kind code	A1
Filing date	Jul 28, 2014
Priority date	Jul 26, 2013
Publication date	Dec 29, 2016
Grant date	—

Abstract

(57) Abstract: The present invention concerns a process for the production of wind turbine structures. In the process, a stack of prepregs is located inside a vacuum bag. Each of the prepregs comprises a mixture of fibrous reinforcement and from 20% to 85 wt % of an epoxy resin of EEW 150 to 1500 and containing from 0.5 to 10 wt % of a curing agent. The curing agent comprises a urea curing agent and an imidazole curing agent, and is free of dicyandiamide. The epoxy resin is cured by application of an externally applied temperature in the range 70° C. to 110° C. for a period of from 4 to 8 hours.

First claim

1 . A prepreg comprising a mixture of a fibrous reinforcement and an resin containing from 20% to 85% by weight of an epoxy resin of EEW from 150 to 1500 said resin being curable by an externally applied temperature in the range of 40° C. to 110° C., wherein the resin contains from 0.5 to 5 wt % of a curing agent, the curing agent comprising a urea curing agent and an imidazole curing agent, and the resin is cured in the absence of a dicyandiamide hardener.

2 . A stack of prepregs comprising a prepreg according to claim 1 .

3 . A prepreg according to claim 1 that can be cured in less than eight hours.

4 . A stack of prepregs according to claim 2 having a thickness of from 2 mm to 100 mm.

5 . A stack of prepregs according to claim 2 in which the curing agent is urea based or imidazole based.

6 . A prepreg according to claim 1 comprising from 20 to 85 wt % of epoxy resin and from 80 to 15 wt % of fibres.

7 . (canceled)

8 . (canceled)

9 . A laminate comprising a cured prepreg according to claim 1 which has been cured.

10 . (canceled)

11 . A process of curing the epoxy resin within a prepreg according to claim 1 , the process involving exposing the prepreg to an externally applied temperature in the range 40° C. to 110° C. for up to 8 hours at a pressure of less than 3.0 bar absolute, said resin containing from 0.5 to 10 wt % of a curing agent and being free of a latent hardener.

12 . A process according to claim 11 in which the resin is free of dicyandiamide.

13 . A process according to claim 11 to claim 12 in which the epoxy resin has an EEW of from 200 to 500.

14 . A process for the production of wind turbine structures comprising providing a prepreg or stack of prepregs within a vacuum bag, the prepregs comprising a mixture of fibrous reinforcement and from 20% to 85 wt % of an epoxy resin of EEW 150 to 1500 and containing from 0.5 to 10 wt % of a curing agent, the curing agent comprising a urea curing agent and an imidazole curing agent, and being free of dicyandiamide, placing the vacuum bag within a mould and creating a vacuum within the bag prior to or after placement in the mould and curing the epoxy resin by application of an externally applied temperature in the range of 40° C. to 110° C. for a period of from 4 to 8 hours.

15 . A resin matrix comprising an epoxy resin containing from 20% to 85% by weight of an epoxy resin of EEW from 150 to 1500 said resin being curable by an externally applied temperature in the range of 40° C. to 110° C., the resin containing from 0.5 to 5 wt % of a bis urea curing agent, and an imidazole, the resin being curable in the absence of a dicyandiamide hardener.

16 . A wind turbine blade or component produced from a resin matrix as defined in claim 15 in combination with a fibrous reinforcement.

17 . A prepreg according to claim 1 , comprising the matrix of claim 15 wherein the curing agent is isolated from the remainder of the resin matrix.

18 . A prepreg according to claim 1 , wherein the urea curing agent and/or the imidazole curing agent is isolated from the epoxy resin or the remainder of the resin matrix.

Assignees

• Hexcel Composites Ltd

Inventors

• Hadley Philip
• Whiter Mark
• Harrington Chris

Classifications

• B29L2031/085

  Wind turbine blades · CPC title

• B32B5/26

  another layer {next to it} also being fibrous or filamentary {(relative arrangement of fibres or filaments of different layers B32B5/12)} · CPC title

• F03D1/0675

  of the blades · CPC title

• B32B27/38

  comprising epoxy resins · CPC title

• F05B2280/6003

  Composites; e.g. fibre-reinforced · CPC title