The car seat is generally composed of a seat skeleton, an adjustment mechanism, a skin, a foamed plastic filling, and a plastic attachment part 5.
The steel in the seat frame and adjustment structure is generally 08 aluminum. Note that this is a steel, not aluminum.
Foamed plastic fillers are polyurethane foams and are usually made from a mixture of TDI (tolyl diisocyanate) and MDI (diphenylmethane-diisocyanate).