Process for radiation curing of EPDM roof sheeting utilizing crosslinking promoters
AssigneeThe Firestone Tire & Rubber Company
InventorsJoseph K. Valaitis, James A. Davis
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Abstract
EPDM roof sheeting is prepared by ionizing radiation curing of a sheet calendered from 100 parts uncured EPDM elastomer, 40-150 parts carbon black, 30-100 parts process oil and an ionizing radiation crosslinking promoter. Preferably, the promoter is dicumyl peroxide, .alpha.,.alpha.'bis (t-butylperoxy) diisopropylbenzene, liquid high vinyl 1,2-polybutadiene resin or ethylene glycol dimethacrylate and an average dose of ionizing radiation of about 15 to about 35 megarads is used to produce sheeting meeting RMA (Rubber Manufacturers Association) Roofing Council tensile strength and elongation requirements for non-reinforced black EPDM rubber sheeting used in roofing applications.
Claims10
A process for preparing EPDM sheeting suitable for roofing purposes, said process comprising the steps of
- (a) preparing a sheet having a thickness ranging from 10 to 150 mils composed of composition comprising (i) 100 parts uncured ethylene-propylene-diene (EPDM) elastomer containing an ethylene to propylene ratio ranging from about 3:1 to about 1:3, from about 2 to about 15 double bonds per 1000 carbon atoms and a number average molecular weight ranging from about 20,000 to about 200,000, (ii) from about 40 parts to about 150 parts carbon black, (iii) from about 30 parts to about 100 parts process oil and (iv) an amount of compatible radiation crosslinking promoter effective to promote curing in step (b), said radiation crosslinking promoter being selected from the group consisting of organic peroxides and liquid high vinyl 1,2-polybutadiene resin,
- (b) treating said sheet with ionizing radiation to provide cured EPDM sheeting, said ionizing radiation being directed at both sides of the sheet.
Dependencies are inferred from the claim text.