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US 4,358,499 AGranted
Dimensionally stable PVC roof membrane
AssigneeThe General Tire & Rubber Company
InventorLawrence I. Hill
Life of this patent
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Abstract
A PVC roofing membrane cast from a plastisol has less than 1.5% shrinkage when held at 176.degree. F. (80.degree. C.) for six hours and remains flexible at -60.degree. F. (-51.degree. C.). The low shrinkage reduces tensions in the roofing membrane, simplifying the application of the membrane to a roof, and reducing stresses caused by dimensional changes at high service temperatures.
Claims1
In a PVC roofing membrane having a thickness of from 20 to 80 mils, the membrane consisting essentially of:
- (a) 100 parts of PVC
- (b) 55 to 75 parts of plasticizer
- (c) 0.1 to 10 parts of emulsifier
- (d) 1 to 30 parts of filler
- (e) 1 to 30 parts of heat and processing stabilizer;
- and
- (f) 1 to 30 parts of UV stabilizer,
- the improvement comprising the membrane being formed by casting and gelling a first layer of plastisol, then casting and gelling a second layer of plastisol on top of the first layer, then fusing both layers to produce a membrane which is elastic and flexible at minus 60.degree. F. and has less than 1.5% shrinkage at 175.degree. F. for six hours.
5 more elements
Dependencies are inferred from the claim text.