Thermoplastic single ply protective covering
View Patent ↗Improved single ply, water proof roof coverings having an extruded pressure sensitive rubber-based adhesive backing for attachment to a substrate such as the roof of a building or a transport vehicle, the adhesive comprising a thermoplastic rubber containing at least 25% butyl rubber in combination with polyisobutylene and low molecular weight polybutene.
1. A single ply thermoplastic roofing membrane coated on its bottom surface with a 1-50 mil layer of a non-cured, non-curable, pressure sensitive adhesive mixture consisting essentially of
(a) a thermoplastic rubber containing at least 25 wt. % butyl rubber;
(b) a polyisobutylene having a number average molecular weight of from about 70,000 to about 400,000 and
(c) a polybutene having a number average molecular weight of from about 700 to about 2,700, wherein said mixture contains approximately equal portions of butyl rubber, (b) and (c) and optionally contains a minor amount of a thickener, thinner, and/or antioxidant.
2. The improvement of claim 1 wherein said adhesive contains between about 32 and about 34 wt. % butyl rubber based polymer, between about 32 and about 34 wt. % poly(isobutylene) and between about 30 and about 36 wt. % poly(butene).
3. The improvement of claim 1 wherein the single ply membrane is fortified with a scrim of random or woven fibers.
4. The improvement of claim 1 wherein the single ply membrane is non-fortified.
5. The improvement of claim 1 wherein the pressure sensitive adhesive mixture contains up to about 3 wt. % of a thickener or thinner.
6. The improvement of claim 1 wherein the pressure sensitive adhesive mixture contains up to about 5 wt. % of an antioxidant or rubber tackifier.
7. The improvement of claim 6 wherein the rubber based polymer is selected from the group consisting of a polymer of styrene/butadiene, styrene/butadiene/styrene, styrene/isoprene/styrene and styrene/ethylene/butadiene/styrene.
8. The improvement of one of claims 3 and 4 wherein an adhesive adsorbing layer is annealed to the undersurface of the single ply membrane between the membrane and the pressure sensitive adhesive coating.
9. The improvement of claim 1 wherein the free surface of the adhesive is covered with kraft paper or a silicone treated release sheet and packaged as a roll of ply material.
10. The improvement of claim 1 wherein a portion of the pressure sensitive adhesive (a), (b) and (c) or a portion of (a) alone is replaced with a pressure sensitive adhesive selected from the group consisting of an acrylate polymer and a polyurethane and a mixture thereof.