Method for forming a layer of blown cellular urethane on a carpet backing

Claim 1

Method for producing a layer of flexible chemically blown urethane foam cushion having a density of between one and ten pounds per cubic foot on the back of a carpet product, in which a mixture of reactive urethane forming components, including isocyanate and polyol, is prepared, the mixture is depositioned on a carrier belt, the back of a preheated carpet product is brought into contact with the mixture, and the mixture which is in contact with the carpet back is chemically blown in a heated urethane foaming station into an enlarged layer of cellular urethane and cured under the effect of heat, comprising the steps of: (1) mixing the reactive components together in a traversing mixer at a temperature of between 60° and 100° F. and dispensing the mixed components onto an endless carrier belt which has been cooled to a temperature of between 50° and 100° F., said reactive components including water at a concentration of 0.01 to 5.0 parts per hundred parts of polyol over and above the water normally present in the reaction mixture and a catalyst which will promote a polyurethane formation reaction and concurrently promote a chemical blowing reaction so that an expansion of between 500 percent and 6400 percent is obtained for the polyurethane material; (2) partially reacting the mixed components on the carrier belt by heating the mixed components to a temperature of between 90° and 150° F.; (3) preheating the lower surface of an uncoated carpet material to a temperature of between 100° and 300° F.; (4) bring the lower surface of the preheated carpet material into flush contact with the partially reacted urethane component mixture; (5) passing the carrier belt, with its urethane mixture, and the carpet material through a urethane forming station at the same speed; (6) heating the urethane mixture to a temperature of between 120° and 200° F. in the urethane forming station for a period of 15 seconds to 120 seconds and permitting upward movement of the carpet material as the reactive urethane mixture chemically blows during urethane formation; and (7) curing the blown urethane foam by heating the foam to a temperature of between 150° and 350° F.