Title:  INCREASING THE SOUND ABSORPTION IN FOAM INSULATING MATERIALS

 Number/Link: WO2013/007243  (German)

Applicant/Assignee: OTTO BOCK SCHAUMSYSTEME GMBH

Publication date: 17-01-2013

“Gist”: Use of  expandable graphite to improve sound absorption and sound insulation properties of  integral skin foams.

Why it is interesting: Expandable graphite is well known as an intumescent flame retardant in coatings and in e.g. low-density (semi-) rigid PU foams, including acoustic foams. This case claims the use of 5-40% (w/w on polyol) of non pre-expanded expandable graphite in a (preferably) 200-300 kg/m3 integral skin foam, resulting in improved sound absorption coefficients and sound insulation (transmission loss?).  It is contemplated that it is the layered structure of the graphite that absorbs the acoustic energy…