hmmmm..... JW's link proves this stuff exists!

Here's another link (perhaps even less reliable:
http://www.jeelysports.com/e_productshow...-Cloth-987.html

JW's link mentions it is used to manufacture high end snowboards and kayaks. My link mentions defense applications.... all possible leads... I'm still looking for a US source.

edit: These guys may be able to help you: https://www.skarrarmor.com/uhmwpe-fabric

edit2: https://www.ebay.com/itm/1500-Denier-50-...m4383.l4275.c10

edit3: I think Spectra is the same material you are looking for. You could contact Ursack and see if they would be willing to sell you some, or get you in contact with a source for the material.