Welcome to the search.
Some of what you are looking for I found in large sizes of Sea-To-Summit Escapist tarps, with a coated fabric weight of 1.08 oz/yd (tested by Richard Nisley on BPL)
Similar weights were found for a Terra Nova Tarp fabric and a 20 D fabric from Extrem Textil, but these were all silicone coated, which is not what you are asking for.
But if you want to go lower on the denier, there is the 7D mini-ripstop nylon from Rockywoods, which is spec’d to have a sil/pu coat.
Note that some of the 15D can be as heavy as some 20D (or someone is just guessing on the denier), so knowing the actual finished, or coated weight can be as important as knowing the denier.
Also, some of the materials, like the membrane polyesters from RBTR have silicone on one side, and polyurethane on the other. But other materials have the same coating, using both silicone and polyurethane components, on both sides. The latter is what you may be looking for in terms of using either side for bonding.
You might have to buy samples or small tarps, and test them with adhesives such as SeamGrip, one of the few polyurethane adhesives that does not foam, as it is formulated to be a sealant. I found that a compound that was thought on BPL to be a good thinner for SeamGrip actually weakened the bond considerably. So a technique is required that applies a very thin coat of SeamGrip.
Speaking of which, Roger Caffin has posted on BPL about silicone transfer tapes that place a thin coating of silicone adhesive on a material for bonding. Found one 3M product, 3M 91022 clear Silicone Adhesive Transfer Tape, 1″ by 60 yd, 2 mil, 48 rolls per case for under $45 from pack-n-tape.com. But haven’t tried it, so cannot vouch for it. It could be anything. Transfer tapes that people have been using for Cuben might work on the sil/pu compound coatings – I don’t know.
Will be interested to see what others come up with. The market is always changing.
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