The underside of a carpet is also called the backing. It binds the tufts and gives the carpet additional strength and dimensional stability. Most carpets have a double backing:
- the primary backing – to hold the yarns
- the secondary backing which is often a heavy thick layer
Typically most carpet backings used to be made with Styrene Butadien as a binder, This cost effective and durable solution has been used for decades. Allthough there are differences over the world. In Europe Styrene Butadien is in favour, and in the US the share of Vinyl Acetate Ethylene is much larger.
Styrene butadien Latex
Styrene butadien has crosslinking properties that make the binder better resistant against chemicals, but it also tends to age and downgrade like plastics are yellowing. This is because the croslinking nevery really stops.
Vinyl Acetate Ethylene (VAE) binder
VAE is a non crosslinking binder, being thermoplastic, it offers several advantages
- Lower VOC
- Better mechanical recyclability, because it’s thermoplastic
- It supports being materials seperated by the Creasolv process. Therefore the raw materials for a carpet (Yarns, Backing, Filler, Binder) can be seperated cleanly, supporting more efficient recycling
- Lower flammability; to make carpet non-flammable, often flame retardants are used. With VAE typically no, or much less, FR additives are needed