Viscoelastic rebond polyurethane foam structure
A rebond polyurethane foam structure is formed by mixing shredded particles of polyurethane foam wherein at least 20% by weight of such particles comprise particles of viscoelastic polyurethane foam. The foam particles are wetted with a liquid prepolymer binder that is cured when the wetted admixture is compressed at a compression ratio of at least about 3. Despite the small viscoelastic foam particle size and the effects of compression and binder curing, the resulting polyurethane foam structure surprisingly has a viscoelastic (slow recovery) character.
1 . A rebond polyurethane foam structure obtained from the steps of:
(a) providing a mixture of particles of polyurethane foam wherein at least 20% by weight of such particles comprise particles of viscoelastic polyurethane foam;
(b) wetting the foam particles with a liquid prepolymer binder;
(c) compressing the wetted admixture to a compression ratio of at least about 3;
(d) curing the binder with heat or steam to form the rebond polyurethane foam structure.
2 . The rebond polyurethane foam structure of claim 1 , wherein at least 50% by weight of the foam particles are viscoelastic polyurethane foam particles.
3 . The rebond polyurethane foam structure of claim 1 , wherein at least 70% by weight of the foam particles are viscoelastic polyurethane foam particles.
4 . The rebond polyurethane foam structure of claim 1 , wherein 100% by weight of the foam particles are viscoelastic polyurethane foam particles.
5 . The rebond polyurethane foam structure of claim 1 , wherein the mixture contains scrap materials selected from the group consisting of: polyether polyurethane foam, polyester polyurethane foam, plastics and fibers.
6 . The rebond polyurethane foam structure of claim 1 , wherein the liquid prepolymer binder is added to the particles in an amount of at least from about 15% by weight, based on 100% by weight of the foam particles plus binder.
7 . The rebond polyurethane foam structure of claim 1 , wherein the resulting rebond polyurethane foam structure has a density in the range of from 5 to 25 pounds per cubic foot (80.1 to 400.5 kg/m 3 ).
8 . The rebond polyurethane foam structure of claim 1 , wherein the resulting rebond polyurethane foam structure has a density in the range of from 10 to 20 pounds per cubic foot (160.2 to 320.4 kg/m 3 ).
9 . The rebond polyurethane foam structure of claim 1 , wherein the viscoelastic foam particles have a mean particle size diameter of 3/16 inch (0.48 cm) or below.
10 . The rebond polyurethane foam structure of claim 1 , wherein the viscoelastic foam particles have a mean particle size diameter of ⅛ inch (0.16 cm) or below.
11 . The rebond polyurethane foam structure of claim 1 , wherein the binder comprises at least one reactive polyol and at least one reactive isocyanate.
12 . A method for forming a rebond polyurethane foam structure, comprising:
(a) providing a mixture of particles of polyurethane foam wherein at least 20% by weight of such particles comprise particles of viscoelastic polyurethane foam;
(b) wetting the foam particles with a liquid prepolymer binder;
(c) compressing the wetted admixture to a compression ratio of at least about 3;
(d) curing the binder with heat or steam to form the rebond polyurethane foam structure.
13 . The method of claim 12 , wherein at least 50% by weight of the foam particles are viscoelastic polyurethane foam particles.
14 . The method of claim 12 , wherein at least 70% by weight of the foam particles are viscoelastic polyurethane foam particles.
15 . The method of claim 12 , wherein 100% by weight of the foam particles are viscoelastic polyurethane foam particles.
16 . The method of claim 12 , wherein the mixture contains scrap materials selected from the group consisting of: polyether polyurethane foam, polyester polyurethane foam, plastics and fibers.
17 . The method of claim 12; wherein the resulting rebond polyurethane foam structure has a density in the range of from 5 to 25 pounds per cubic foot (80.1 to 400.5 kg/m 3 ).
18 . The method of claim 12 , wherein the resulting rebond polyurethane foam structure has a density in the range of from 10 to 20 pounds per cubic foot (160.2 to 320.4 kg/m 3 ).
19 . The method of claim 12 , wherein the foam particles have a mean particle size diameter of 3/16 inch (0.48 cm) or below.
20 . The method of claim 12 , wherein the foam particles have a mean particle size diameter of ⅛ inch (0.16 cm) or below.
21 . The method of claim 12 , wherein the liquid prepolymer binder is added in an amount of at least from about 15% by weight, based on 100% by weight of the foam particles plus binder.
22 . The method of claim 12 , wherein the binder comprises at least one reactive polyol and at least one reactive isocyanate.
23 . A carpet cushion or floor underlayment comprising a rebond polyurethane foam structure of claim 1 .
24 . A carpet cushion or floor underlayment comprising a rebond polyurethane foam structure made by the method of claim 12 .
25 . A rebond polyurethane foam structure, comprising:
a matrix of foam particles and optional other scrap material bound under compression with a cured binder, wherein at least 20% by weight, based on the weight of the foam particles, constitute viscoelastic foam particles, and wherein said matrix has a density of at least 10 pounds per cubic foot (160.2 kg/m 3 ) and a hysteresis above about 65%.
26 . The rebond polyurethane foam structure of claim 25 , wherein at least 50% by weight of the foam particles constitute viscoelastic foam particles.
27 . The rebond polyurethane foam structure of claim 25 , wherein at least 70% by weight of the foam particles constitute viscoelastic foam particles.
28 . The rebond polyurethane foam structure of claim 25 , wherein the foam particles comprise in part particles of nonviscoelastic resilient polyether or polyester polyurethane foam.
29 . The rebond polyurethane foam structure of claim 25 , wherein the scrap material is present and is one or more materials selected from the group consisting of: plastics, textiles and fibers.
30 . A carpet cushion or floor underlayment incorporating the rebond polyurethane foam structure of claim 25.