Method for making polyurethane foam floor covering products with postconsumer carpet fibers

Abstract

Polyurethane floor covering products are formed from a web layer containing at least 30% by weight fibers. A cooled polyurethane foam formulation which includes at least one polyisocyanate, water and at least one polyol having an equivalent weight of at least 500 is applied to the web layer. The wetted web layer is then compressed to mechanically wet out the fibers, gauged and heated to cure the foam formulation.

Claims

1. A process for preparing a foamed polyurethane floor covering product that includes a cured and gauged polyurethane foam cushion containing from 5 to 50% by weight of the fibers, comprising: a) forming a web layer containing at least 30% by weight fibers, such that the web layer has a weight of from 150 to 660 g/m.sup.2 and a thickness of 0.25 to 1 inch, and the fibers in the web layer have an average length of from 7 to 140 cm and a denier of 5 to 50; b) continuously applying a cooled polyurethane foam formulation which includes at least one polyisocyanate, water and at least one polyol having an equivalent weight of at least 500 to the web layer, the cooled polyurethane foam formulation having a temperature of no more than 15 C. when applied to the web layer, and compressing the web layer and applied polyurethane foam formulation together to 5 to 35% of the original thickness of the web layer to mechanically wet out the fibers in the web layer; and then c) gauging the wetted web layer to a thickness of from 0.25 to 1.0 inches and, while maintaining the gauge, heating the polyurethane foam formulation to a temperature of from 80 to 160 C. to cure the polyurethane foam formulation to produce a cured and gauged polyurethane foam cushion containing from 5 to 30% by weight of the fibers.

2. The process of claim 1, wherein the cooled polyurethane foam formulation has a temperature of not more than 10 C. when applied to the web layer.

3. The process of claim 1, wherein the web layer contains at least 50% by weight of fibers.

4. The process of claim 1, wherein the web layer comprises carded fibers.

5. The process of claim 1, wherein the fibers are obtained from postconsumer carpeting products.

6. The process of claim 1, wherein the foamed polyurethane floor covering product has a density of from 3 to 10 pounds/cubic foot (48-160 kg/m.sup.3).

7. A foamed polyurethane floor covering product produced by the process of claim 1.

Description

EXAMPLE 1

(1) A formulated polyol mixture is prepared by mixing 1200 parts by weight of a 1700 equivalent weight, nominally trifunctional, amine-initiated polyol, which is prepared according to the general process of U.S. Pat. No. 6,762,274, 12 parts of an 85% solution of diethanolamine in water, 43.7 parts water and 18 parts of a 33% solution of triethylenediamine in dipropylene glycol. These are mixed thoroughly and cooled to 7 C.

(2) Shredded post consumer carpet fibers, containing mainly nylon fibers about 8.5+/4.8 cm in length, are carded and formed into a 30.530.5 layer weighing 20.9 g. This web layer is sandwiched between two layers of polyethylene release film, and placed into a 30.5 cm30.5 cm1.11 cm open-top mold which is preheated to 121 C. The web layer is heated in the mold for 30 minutes to drive off residual water from the layer and cooled back down to ambient temperature. The top release film layer is pulled back, and a 3500 g, 30.4-cm long roller having a diameter or 4.5 cm is placed at one end of the open mold. 104.64 g of the cooled polyol mixture is mixed with 66.08 g of a cooled (7 C.) PMDI product having an isocyanate content of 29.4% (SPECFLEX NE 134 isocyanate, from The Dow Chemical Company), and 65 g of the resulting polyurethane foam formulation is immediately poured over the carded fiber web in the mold. The release film is replaced, and the roller is pulled down across the mold on top of the release film, compressing the fiber web and causing the individual fibers to become wetted with the polyurethane foam formulation. The top is then placed onto the mold, the mold is placed in a 121 C. oven, and the polyurethane foam formulation is allowed to cure for five minutes at 121 C. The mold is removed from the oven and the sample is removed. The sample is aged for 7 days under the conditions specified in ASTM 3675-78 for performance property testing. Density, compression set and sample thickness are measured according to ASTM 3675-78. ILD is measured according to ASTM 3574-78.

(3) Compression set is measured as follows. 22 (5 cm5 cm) foam specimens are formed into 2 stacks of plied specimens each approximately 1 inch (2.5 cm) thick. The stack is placed in an Instron tensile testing device equipped with a circular presser foot one square inch (6.45 cm.sup.2) in area, and the thickness of the specimen is measured at an applied load of 100 grams per square inch (100 g/6.45 cm.sup.2)

(4) The specimen is then compressed to 50% of its original thickness between two parallel plates which are each larger than the specimen area. The specimen is then held at this compressed thickness and heated in a circulating air oven at 70 C. for 22 hours.

(5) The specimen is then removed from the oven and allowed to re-expand. It is returned to the oven for 0.5 hour, and then allowed to cool for 5 to 10 minutes. The thickness is then remeasured as before. The compression set is calculated as
C.sub.f=100(t.sub.ot.sub.f)/t.sub.o
where C.sub.f is the compression set, t.sub.o is the original thickness and t.sub.f is the final specimen thickness.

(6) Ball rebound is determined according to ASTM D3574-86 Test Method H, modified in that the sample size is 26 inches (2.515 cm), and the height of the sample is built up to about 1 inch (2.5 cm) by stacking multiple layers of the composite.

(7) 25% ILD is measured as follows. Enough 26 (2.515 cm) skived composite specimens are stacked to form a stack of plied specimens each approximately 1 inch (2.5 cm) thick. The stack is placed in an Instron tensile testing device equipped with a circular presser foot one square inch (6.45 cm.sup.2) in area, and the thickness of the specimen is measured at an applied load of 100 grams per square inch (100 g/6.45 cm.sup.2). The specimen is compressed to 75% of its original thickness, using the one square inch pressure foot, and the load required to so compress the specimen is determined. This reading is the compression resistance of the foam. The procedure is repeated on a duplicate stack and the results are averaged.

(8) Retention of 25% ILD is determined as follows. 25% ILD is measured on a sample as described above. The sample is then subjected to 12,000 compression cycles on a Hexapod tester, which simulates repeated foot traffic over the sample, and 25% ILD is re-measured as before. The retention of 25% ILD is calculated as the second 25% ILD measurement as a percentage of the initial 25% ILD measurement.

(9) Results of the foregoing testing are as indicated in Table 1. The properties of a commercially available rebond carpet underlayment product are given for comparison.

(10) TABLE-US-00001 TABLE 1 Commercial Rebond Property Example 1 Underlayment Cure time, min. 5 NA Sample weight, g/m.sup.2 1016 1098 Post-consumer fiber 22 0 content, % Pad density, kg/m.sup.3 80.4 96.4 Thickness, mm 12.6 11.3 25% ILD, kPa 25.5 22 50% compression set, % 15 14 Ball rebound, % 41 30 25% ILD retention, % 60 54

(11) The data in Table 1 shows that Example 1 has an ILD, compression set and ball rebound values that closely approximate those of the commercial rebond material, even though the density and pad weight are lower for Example 1, and even though Example 1 contains a significant post-consumer fiber content. The ILD retention for Example 1 is better than that of the commercial rebond material, too.

(12) Despite the absence of a surfactant, the cushion has a good uniform cell structure and good properties.

EXAMPLE 2

(13) Example 1 is repeated, using the following formulated polyol mixture instead of that described in Example 1: 1030 equivalent weight, nominally trifunctional, random copolymer of 87% propylene oxide and 13% ethylene oxide: 19 parts 1550 equivalent weight, nominally trifunctional ethylene oxide-capped poly(propylene oxide) having 88% primary hydroxyl groups 81 parts 85% solution of diethanolamine in water: 0.6 parts Silicone surfactant: 1.5 parts Water: 3.61 parts 33% solution of triethylenediamine in dipropylene glycol: 0.17 parts 30% bis(dimethylaminoethyl)ether in dipropylene glycol: 0.12 parts

(14) Conditions otherwise are identical to those of Example 1, except the mold temperature is only 100 C.

(15) Properties are measured as for Example, with the results being as indicated in Table 2:

(16) TABLE-US-00002 TABLE 2 Property Example 1 Cure time, min. 5 Sample weight, g/m.sup.2 997 Post-consumer fiber content, % 28 Pad density, kg/m.sup.3 72.4 Thickness, mm 12.7 25% ILD, kPa 15.1 50% compression set, % 15 Ball rebound, % 35.7 25% ILD retention, % 77.5