Polyurethane prepolymers, rebonded polyurethane foam and methods of forming the same

A polyurethane prepolymer that is a homogeneous solution consisting of the reaction product of (a) an isocyanate selected from the group consisting of tolylene diisocyanate, tolylene diisocyanate residue, polymethylene poly(phenlyeneisocyanates), and blends thereof and (b) a polyoxyalkylene polyol having an oxyethylene content of from about 30 to 100 percent by weight, the oxyalkylene groups in the polyol being oxyethylene groups or oxyethylene groups and oxypropylene groups and said prepolymer having a free NCO content of from about 2 to 20 percent by weight, with the proviso that, when the oxyethylene content of the polyol is 100 percent by weight, the isocyanate is other than tolylene diisocyanate.

A polyurethane prepolymer that is a homogeneous solution consisting of the reaction product of (a) an isocyanate selected from the group consisting of tolylene diisocyanate residue, polymethylene poly(phenyleneisocyanates), and blends thereof and (b) a polyoxyalkylene polyol having an oxyethylene content of from about 30 to 100 percent by weight, the oxyalkylene groups in the polyol being oxyethylene groups or oxyethylene groups and oxypropylene groups and said prepolymer having a free NCO content of from about 2 to 20 percent by weight.

A polyurethane prepolymer that is a homogeneous solution consisting of the reaction product of (a) an isocyanate selected from the group consisting of tolylene diisocyanate, tolylene diisocyanate residue, polymethylene poly(phenlyeneisocyanates), and blends thereof and (b) a polyoxyalkylene polyol having an oxyethylene content of from about 30 to 70 percent by weight, the oxyalkylene groups in the polyol being oxyethylene groups and oxypropylene groups and said prepolymer having a free NCO content of from about 2 to 20 percent by weight.

A rebonded polyurethane foam comprising a block of foam particles having dimensional stability and said particles being bonded together by a cured polyurethane prepolymer, said prepolymer consisting of the reaction product of (a) an isocyanate selected from the group consisting of tolylene diisocyanate, tolylene diisocyanate residue, diphenylmethane diisocyanate, polymethylene poly(phenyleneisocyanates), and blends thereof and (b) a polyoxyalkylene polyol having an oxyethylene content of from about 30 to 100 percent by weight, the oxyalkylene groups in the polyol being oxyethylene groups or oxyethylene groups and oxypropylene groups and said prepolymer having a free NCO content, prior to curing, of from about 2 to 20 percent by weight and being present in an amount of no more than about 6 percent based on the total weight of the block constituent including the prepolymer.

A method of forming a rebonded polyurethane foam having dimensional stability from foam particles which comprises blending the foam particles, introducing, during the blending, a polyurethane prepolymer consisting of the reaction product of (a) an isocyanate selected from the group consisting of tolylene diisocyanate, tolylene diisocyanate residue, diphenylmethane diisocyanate, polymethylene poly(phenyleneisocyanates), and blends thereof and (b) a polyoxyalkylene polyol having an oxyethylene content of from about 30 to 100 percent by weight, the oxyalkylene groups in the polyol being oxyethylene groups or oxyethylene groups and oxypropylene groups and said prepolymer having a free NCO content of from about 2 to 20 percent by weight and being present in an amount of no more than about 6 percent based on the total weight of the block constituent including the prepolymer, compressing the foam particles and prepolymer blend to form a block of the desired dimensions, curing the foam particles and prepolymer to the extent that said block has dimensional stability and removing the resulting block from compression.