heat transfer onto rolldown sunshade??

You don't want to use plastisol transfers for that, maybe sublimation if it's polyester but most likely you'll need to sub it to a sign shop and they'll need the shade disassembled or they may be able to print on a vinyl that can be adhered to the shade assembled.

you cannot use sublimation as that will not last in sunlight...even with a filter...

i need to buy some rolldown sun shades. what materials would work for vinyl transfers?

I am only guessing but I would think that those shades wouldn't hold up to the heat and would shrink or distort when pressed

Sublimation if it was a polyester cloth shade would last a long time. I have sublimated outdoor signs that are over 5 years and 0 fade.

Have you thought of trying to use sign vinyl, maybe Oracal 951 or similar. It's not quite as thin as transfer vinyl, but still not too bad. Premium sign vinyl claims 5 - 7 years for most colors. I don't think rolling and unrolling would adversely affect the vinyl. You might need to be a little creative depending on the shade being slatted or solid. Just a thought! If you do decide to try sign vinyl make sure to use a cast vinyl, not a calendered vinyl. The cast vinyl does not develop cracks or splits in the corners like the calendered does.

Solar 210 from Imprintables.......