What is the back of the artificial turf made of?

There are two components for artificial grass backing: 

1. Primary backing: this is the cloth that artificial grass fibers to be tufted onto. We use polypropylene primary backings for all of our turf products. More importantly, we use two layers of such materials to enhance the stabilities and durabilities of our products. 

2. Secondary backing: Once turf being tufted onto the primary backing, all fibers are loosely attached, in order to secure them from falling out or been pulling out, we use polyurethane glue to glue the fibers onto the primary backing. Polyurethane glues are very ideal for this application, as it will not react to moistures and have great binding power to hold fibers in place for years to come.

Generally people are referring the glues on the back of turf as its backing and reality is that there are two backings for artificial grass: primary and secondary.