Low density flame retardant two-component composition for structural void filling

A two-component system of a

• (i) first component comprising one or more curable polymers;
• and
• (ii) a second component comprising one or more curing agents for the one or more curable polymers;
• wherein the first component and the second component each comprise low density polymeric microspheres in an amount of 3 wt % or less and at a relative weight ratio of about 2:1 (first component:
• second component) so that the each of the first and second component has a viscosity of 50 to 300 Pa·s as measured in accordance with ASTM D445 for in-use storage stability in a two-chamber cartridge;
• and
• wherein at least one of the first and second component comprise:
• an ammonium polyphosphate;
• or
• a metal hydroxide;
• wherein the first component and the second component are spatially separated from one another;
• wherein the reaction of the first component and the second component at 23° C. after mixing with one another results in a cured material;
• and
• wherein the cured material has a cured density of at most 0.550 g/cm−3 as determined according to EN ISO 1183.