	US 12,343,908 B2
	Process for producing polymethyl methacrylate rigid foams as core materials in rotor blades of wind power plants and in boatbuilding
Thomas Richter, Darmstadt (DE); Christoph Seipel, Babenhausen (DE); Vincent Ma Junyong, Darmstadt (DE); Florian Becker, Darmstadt (DE); and Lisa Langel, Mannheim (DE)
Assigned to Evonik Operations GmbH, Essen (DE)
Appl. No. 17/632,961
Filed by Evonik Operations GmbH, Essen (DE)
PCT Filed Jun. 24, 2020, PCT No. PCT/EP2020/067571 § 371(c)(1), (2) Date Feb. 4, 2022, PCT Pub. No. WO2021/023432, PCT Pub. Date Feb. 11, 2021.
Claims priority of application No. 19190719 (EP), filed on Aug. 8, 2019.
Prior Publication US 2022/0339829 A1, Oct. 27, 2022
Int. Cl. B29C 44/12 (2006.01); B29C 35/08 (2006.01); B29C 44/02 (2006.01); B29C 44/06 (2006.01); B29C 44/34 (2006.01); B29K 33/00 (2006.01); B29L 31/08 (2006.01)

CPC B29C 44/12 (2013.01) [B29C 35/0805 (2013.01); B29C 44/02 (2013.01); B29C 44/06 (2013.01); B29C 44/3415 (2013.01); B29K 2033/12 (2013.01); B29K 2995/0063 (2013.01); B29L 2031/085 (2013.01); B29L 2031/087 (2013.01); Y02E 10/72 (2013.01)]

15 Claims

1. A process for producing a rotor blade for use in a wind power plant or boatbuilding, the process comprising employing a polymethyl methacrylate-based rigid foam in sandwich components to make the rotor blade

wherein the polymethyl methacrylate-based rigid foam in sandwich components is made by the process comprising:

foaming a blowing agent-laden polymer composition to afford a polymethyl methacrylate-based rigid foam having an average pore size in the range from 50 to 300 μm measured according to ASTM D3576 to form a core material for the sandwich components, and

curing a resin during production of the sandwich components at a temperature greater than 110° C. by heating or irradiating in a mould,

to form an outer layer around the core material,

wherein the polymethyl methacrylate-based rigid foam has a glass transition temperature Tg above 110° C. determined by DMTA measurement according to ISO 6721-7 standard,

wherein a resin absorption of the polymethyl methacrylate-based rigid foam is 0.01 to 0.03 g/cm²measured according to VARI, and

wherein during production of the sandwich components, the polymethyl methacrylate-based rigid foam is injected with an epoxy resin and the epoxy resin is cured at a temperature of 110° C.