cuben fiber and iron on patches?

Would they stick regardless?

As with all iron-on patches, the heat activates the adhesive.

I suspect the Mylar layer would melt but that is just speculation.   It would be an expensive mistake if it didn’t work.

What about sewing a piece of Cuben to the back of the patch and taping it on?

Fabric glue?

I figured CF would not withstand the high heat of an iron and I’d have to sew the patch on, but figured I’d put it out there, just in case someone had tried it and succeeded.

I don’t think many chemical based fabrics can survive high temperatures without melting.  I know someone who pitched his cuben shelter too close to a fire and got small holes in it from the sparks.  Though it was the lighterweight stuff.

The UHMW PE fiber in the cuben fabric loses strength at 120C (250F).  Mylar melts well above the 200C (400F) you cited but it can shrink at temps as low as 80C (180F).  Many glues adhere to Mylar without the heat cure.

Why not use some of the double sided tape that is used to build DCF shelters? I’d guess whatever adhesive is on the back of the patch would stick just fine to that, activated or not.

Use one of THESE instead, or try THIS.