US 12,233,582 B2
Foaming of blowing agent containing polymers through the use of microwaves
Thomas Richter, Darmstadt (DE); Christoph Seipel, Babenhausen (DE); Christian Traßl, Warmensteinach (DE); Andreas Liebe, Darmstadt (DE); Florian Becker, Darmstadt (DE); and Vincent Ma Junyong, Darmstadt (DE)
Assigned to Evonik Operations GmbH, Essen (DE)
Appl. No. 17/423,152
Filed by Evonik Operations GmbH, Essen (DE)
PCT Filed Dec. 19, 2019, PCT No. PCT/EP2019/086245
§ 371(c)(1), (2) Date Jul. 15, 2021,
PCT Pub. No. WO2020/148066, PCT Pub. Date Jul. 23, 2020.
Claims priority of application No. 19152184 (EP), filed on Jan. 16, 2019.
Prior Publication US 2022/0126490 A1, Apr. 28, 2022
Int. Cl. B29C 44/34 (2006.01); B29C 35/08 (2006.01)
CPC B29C 44/3415 (2013.01) [B29C 35/0805 (2013.01); B29C 2035/0855 (2013.01)] 11 Claims
 
1. A process for producing foams, the process comprising:
foaming a polymer composition comprising a blowing agent in an apparatus consisting of a thermal heating means and a microwave, which in combination heat the polymer composition above a glass transition temperature of the polymer composition TgC to produce a foam,
wherein during foaming the polymer composition is moved relative to a microwave field,
the polymer composition is heated at least 10° C. above the glass transition temperature of the polymer composition Tgc with microwave irradiation and thermal energy,
the polymer composition comprises polymethacrylimide or polymethyl methacrylate; and
a temperature of the thermal heating means is not more than 30° C. below a glass transition temperature of the polymer Top before foaming.