# Is corovin Polypropylene or flat polyester?

I'm wanting to know what material 'corovin' is as described on some duvet covers. Googling it, some places say it is just another name for 'Polypropylene' while other places say it is 'flat polyester' whatever that means.

Which is correct? As far as I'm aware Polypropylene and polyester are different types of synthetic fibers.

Thanks

Companies such as Du Pont, Freudenberg and Corovin began their research and development work on generating spunbonded webs. In Europe, Freudenberg, Terram, and Corovin started production of polypropylene (PP) spunbonded webs at the beginning of the 1970s. Within these technologies, filaments are spun directly out of the polymer melt through small die heads arranged side by side, stretched down to a diameter of $$\pu{10-30 \mu m}$$ and laid down on a porous lay down and transport belt.
The present invention concerns a nonwoven fabric the fibers of which have polyethylene on at least part of their surface, where the fibers are thermally bonded and the non-woven fabric exhibits an abrasion of less than $$\pu{0.5 mg/cm2}$$, in particular of less than $$\pu{0.4 mg/cm2}$$, and an embossed area fraction of less than 35%, in particular of less than 28%. Furthermore a device is made available for the manufacture of a non-woven fabric, using a polyethylene-containing polymer, with a take-down system underneath a spinning plate that causes the take-down of the polyethylene, where the spinning plate has an L/D ratio of between 4 and 9.