In the Skeptics.SE question https://skeptics.stackexchange.com/questions/36602/do-japanese-police-roll-drunks-and-criminals-into-giant-futons , one term used for sheets that police wrap drunks and criminals in is 保護シート. (There's a photo of the sheet in that question)
However, I think most of the time that term is used for the covers on smartphone screens. I tried asking some native speakers, and they said they don't know what the correct term is.
Is there a name for these sheets, and if so, what is it?