Sound Absorbing PU-PA Foams

Title: THERMOFORMABLE RIGID POLYURETHANE-POLYAMIDE FOAM

 Number/Link: US2014/058005

Applicant/Assignee: BASF

Publication date: 27-2-2014

Gist”: Rigid, open-celled and thermoformable polyurethane-polyamide foams are produced using short chain di-acids as both chain extender and blowing agent.

Why it is interesting: The reaction of a carboxylic acid group with an isocyanate group results in a mixed anhydride, which after releasing carbon dioxide forms an amide. Because the reaction is relatively sluggish a  Lewis base catalyst is used, e.g. N-methylimidazole. In this case a rigid foam-forming formulation based on MDI and (pref.) polyether polyols is further reacted with short chain diacids like azelaic- or glutaric acid.  The examples show foam densities of less than 30 kg/m³ without the use of water.  The foams are open celled with high air flow and with a Tg of around 90°C, making them thermoformable.  This type of foams is used as acoustic bonnet- en roofliners in the automotive industry.

Azelaic Acid

Azelaic Acid

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