Manville Service Corporation

John L Sznopek

Charles Lostak

Robert W Heisler

Joseph P Ferraro

Henry J Kazienko

Manfred Klepetar

A method is described for achieving full cure of a peroxide cured polyester resin in the presence of rubber, which method is based on the discovery that there is competition between the uncured resin and the rubber surface for the peroxide curing agent present adjacent to the rubber/resin interface. The method has several embodiments, including: (1) utilizing a low surface activity rubber, (2) deactivating the surface of a high surface activity rubber, (3) utilizing a peroxide material at the interface, (4) utilizing a material with which the rubber surface reacts preferentially, and (5) utilizing a 'rapid cure' for the polyester. Also described is a laminate of rubber and polyester resin formed by this method.

Method of curing polyester resin in the presence of rubber

A coupling comprises a body of fiber glass reinforced plastic which has a rubber sleeve embedded therein. The rubber sleeve is a one piece unit which includes specially shaped sealing gaskets on either end and has a rubber liner spanning the area between these sealing gaskets. This rubber sleeve is stretched onto a steel and plastic molding mandrel. This stretching places the rubber liner under tension which reduces the cross-sectional area of the liner and compensates for thermal expansion of the liner during curing. The mandrel/sleeve combination is rotated in order to wind a thermosetting resin impregnated fiber glass roving around the outer circumference of the mandrel/sleeve combination, thus embedding the sleeve in the fiber glass reinforced resin matrix. The thermosetting resin is cured at elevated temperatures, hardening into a rigid coupling with the embedded rubber sleeve integral therewith. Thereafter the hardened coupling is stripped from the steel and plastic mandrel and subjected to a further curing and finishing operation.

Method of making a coupling for rigid pressure pipe

Mandrel for making a coupling which coupling comprises a body of fiber glass reinforced plastic which has a rubber sleeve embedded therein. The rubber sleeve is a one piece unit which includes specially shaped sealing gaskets on either end and has a rubber liner spanning the area between these sealing gaskets. This rubber sleeve is stretched onto a steel and plastic molding mandrel. This stretching places the rubber liner under tension which reduces the cross-sectional area of the liner and compensates for thermal expansion of the liner during curing. The mandrel/sleeve combination is rotated in order to wind a thermosetting resin impregnated fiber glass roving around the outer circumference of the mandrel/sleeve combination, thus embedding the sleeve in the fiber glass reinforced resin matrix. The thermosetting resin is cured at elevated temperatures, hardening into a rigid coupling with the embedded rubber sleeve integral therewith. Thereafter the hardened coupling is stripped from the steel and plastic mandrel and subjected to a further curing and finishing operation.

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Littleton, CO, United States of America

John L Sznopek