HK1179215B - Method for making polyurethane foam floor covering products with postconsumer carpet fibers - Google Patents

Description

Method for making polyurethane foam floor covering products with post consumer carpet fibers

The present invention relates to a process for preparing polyurethane foam floor covering products.

Used and discarded carpet products present significant disposal problems due to the large volume of these products removed from office buildings, public institutions, and residences each year. These discarded products are mainly sent to landfills, where they occupy a large amount of landfill capacity. The fibers that make up the majority of the weight of the carpet are very difficult to biodegrade, so it is expected that discarded carpets will remain more or less intact in landfills for centuries.

Thus, there is an incentive to recycle some or all of the fiber values that remain in the discarded carpet product. To this end, various methods have been developed to mechanically shred discarded carpet products and recover some or all of the fiber values they contain. An example of this process is described in us patent 5,897,066.

Once the fiber values are recovered, the problem of how to handle them remains. Recycled fibers are not suitable for use in making new carpet face for a variety of reasons. The recycled fibers tend to be severely damaged due to the recycling process itself and the abrasion. They are often contaminated with other components of the carpet product, such as small particles of latex binder, inorganic filler particles, etc., which are difficult to completely separate from the fibers. In addition, the fibers are often already dyed and are often contaminated or contain other absorbed contaminants.

Therefore, additional uses are required for these recycled fibers.

One potential use for these fibers is in carpet underlay mats. Carpet backings are widely installed under carpet materials to provide cushioning. Because the carpet backing is hidden beneath the upper carpet, its appearance is generally unimportant. Consumers do not pay a lot for materials that they cannot see, so low cost is a major concern. As a result, carpet backings are often made from inexpensive raw materials, including waste foam pieces, which are bonded together to form a "re-bonded" material. Carpet backing applications are thus a potential application for fibers recovered from post-consumer carpet products.

For example, U.S. published patent application 2008/0075915 describes a carpet backing using post consumer carpet fibers. The fibers are mixed with foam pieces and a thermal adhesive, formed into a batt, and heated to melt the adhesive, thereby bonding the different components to one another. 2008/0075915 is a sheath/core bicomponent fiber.

Other fibrous carpet backing products are formed by impregnating the fibers with different types of binders. For example, USP4,014,826 describes a process similar to that described at 2008/0075915, wherein a special type of fiber (which is not post consumer fiber) is used. A non-foamed latex or urethane is used as the binder in US4,014,826. In GB599682, GB1,145,932, USP3480456 and us published patent application 2006-0144012 needled fibre batts are impregnated with different thermosetting and/or thermoplastic binder materials. In USP3,952,126, a mixture of polyurethane crumbs and staple fibers are needled to form a batt. In USP4,683,246, filaments and foam crumbs are mixed with a polyurethane prepolymer and steam cured into a dough (buns). USP6,596,387 and U.S. published patent application 2005-0126681 describe forming a mat-like product by forming a double layer of polyurethane or latex foam and a fibrous batt.

USP4,269,889 and USP4,296,054 describe molded polyurethane foams reinforced with polymer fibers to prepare molded foam products for use in, for example, automotive seats. The polyurethane foam formulation is introduced into a mold and then a mass of a particular type of entangled fiber is added. The polyurethane is partially cured in the mold, then demolded and post-cured. This molding process can produce a composite of polyurethane foam and fibers, but is not suitable for producing products with large surface areas, such as carpet backings, because molds of the required size are not available at any reasonable price and cure times are too long to be practical in floor covering production methods. Furthermore, a special type of fiber is necessary in the processes described in USP4,269,889 and USP4,296,054.

To date, none of the above methods have been satisfactory. Floor cushion products must not only be inexpensive to manufacture, but also meet certain performance criteria. These performance criteria are acceptable tear strength, low compression set, adequate load bearing and ability to maintain its cushioning properties during walking, etc.

The present invention is a method of making a foamed polyurethane floor covering product. The method comprises the following steps:

a) forming a mesh layer comprising at least 30 wt% fibers such that the mesh layer has a weight of 150 to 600g/m²And the fibers in the mesh layer have an average length of 0.75 to 40 cm;

b) continuously applying a cooled polyurethane foam formulation to the reticulated layer, the polyurethane foam formulation comprising at least one polyisocyanate, water, and at least one polyol having an equivalent weight of at least 500, and pressing the reticulated layer and the applied polyurethane foam formulation together to mechanically wet out the fibers in the reticulated layer; then the

c) The thickness of the wetted reticulated layer is gauged to 0.25 to 1.0 inches and the gage is maintained and the polyurethane foam formulation is heated to a temperature of 80 to 160 ℃ to cure the polyurethane foam formulation to produce a cured and gauged polyurethane foam cushion comprising 5 to 50 weight percent fibers.

This approach provides a number of advantages. Post consumer fibers, such as those obtained from discarded carpets, are well suited for use in this process. The polyurethane foam and fibers become intimately and highly uniformly distributed in the process, which results in a product with high uniformity and consistency. The product can be prepared at low cost; in particular, the foam formulation often fully cures in 5 minutes or less to produce a foam that exhibits minimal roll set (as described in more detail below). This rapid cure makes the process economically feasible on an industrial scale, where large volumes of product must be prepared continuously and at commercially reasonable line speeds. The rapid cure also makes the process suitable for preparing products having a broad width of 6 feet or more in width. Furthermore, a dense polyurethane skin is often formed on one surface or on both surfaces of the product. The skin may eliminate the need to attach a separate film layer to the surface of the product, which is often attached to prior art carpet backing products to prevent them from absorbing liquids, or for other reasons. The method is also versatile and suitable for preparing a variety of carpet products, including conventional carpet backings as well as attached carpet products.

The method of the present invention begins with the formation of a web-like layer comprising fibers. The fibers may be formed into a web-like layer using any convenient method, such as various foaming and deposition (laydown) methods, or by carding. "carding" is used herein in its general sense to mean the passage of fibers through a process such that they loosen slightly and align the individual fibers so that they become generally parallel to each other. The result is a lightweight "fluffy" material that behaves like a cotton ball, but which still typically has a low weight per unit volume. The fibers themselves are staple fibers having a weight average length of 0.3 inch to 15 inches (0.75cm to about 40cm), preferably 0.75 to 10 inches (1.9 to 25 cm). Preferably at least 80 wt.%, more preferably at least 90 wt.% of the fibers have a length of 0.75 to 10 inches (1.9 to 25 cm).

The fibers are formed into a mesh-like layer such that the weight of the layer per unit area is 150 to 600g/m². The height of the mesh layer will of course depend on the density of the mesh layer, which thus mainly depends on how close the individual fibres are bundled together. Typically, the thickness of the netting layer is about equal to or slightly greater than the thickness of the final product, or about 0.25 to 1.0 inches thick, but the thickness may vary slightly and may vary slightly across the layer.

The mesh layer may be formed by depositing fibers on a suitable surface having a sufficient width. The fibers may be so deposited in a continuous manner immediately followed by application of the polyurethane foam formulation to the layer, in effect combining the step of forming the reticulated layer with the remaining steps of the overall process into a single operation. Alternatively, the mesh layer may be prepared in a preliminary step, in which case the pre-formed mesh layer is stored until needed.

The mesh layer may be needled, heat set, or otherwise treated to entangle the fibers, thereby increasing its mechanical integrity. Similarly, various types of adhesives may be applied to the mesh layer for the same reason. Suitable types of binders include different types of binder fibers as well as liquid, thermoplastic and/or thermosetting binders. However, one advantage of the present invention is that handling such as winding and/or applying adhesive is not necessary to produce a good quality product, and these steps can be, and preferably are, omitted from the process.

The fibers used to make the mesh layer can be of any type that can withstand the temperatures encountered in the curing step. Polymeric fibers such as nylon or other polyamides, polypropylene, polyethylene, polyester, and the like can be used, as can natural fibers such as cotton, hemp, or wool fibers. Carbon fibers may also be used. Waste fibers from industrial processes may also be used, including, for example, selvage trim (selvedge trimming), yarn ends, and the like. However, the use of fibers obtained from post-consumer carpet products is highly preferred, primarily for cost and ecological reasons. These fibers preferably consist of or consist essentially of: fibers of cut or continuous loop pile obtained from pile carpets. These pile fibers can be contaminated with particles of binder materials used in the original carpet to bind the fibers to the backing or backing material, as well as with particles of inorganic materials, such as clays, which are often used as fillers in binder compositions used in constructing pile carpets. The fibers may also comprise a portion of the backing or primary backing material of the original carpet. The fiber denier is suitably from 5 to 50, and more preferably from 10 to 25.

In addition to fibers, the mesh layer may also comprise other materials. The material is preferably soft and flexible so as not to interfere with the cushioning properties of the product, and preferably has a low density. The other materials, if present, should be in granular form having a largest dimension no greater than about 1 inch (2.5cm) and preferably no greater than 1/2 inches (1.25 cm). Polymer foam is a useful additional material if ground or otherwise formed into small pieces. Foamed natural or synthetic rubbers are a preferred type, including polyurethane foams. These polymer foams may be virgin materials, but it is preferred to use waste or post-consumer materials for cost and ecological reasons. If these additional materials are present in the mesh layer, the fibers should constitute at least 30% and preferably at least 50% by weight of the mesh layer.

The polyurethane foam formulation is applied to the mesh layer, and the wetted mesh layer is then compressed to mechanically wet the fibers with the polyurethane foam formulation. The manner in which this process is carried out is not considered critical to the present invention, provided that the polyurethane foam formulation becomes well distributed in the web layer. One convenient way in which these steps are carried out industrially is to place the web-like layer on a moving platform, such as a conveyor belt, tenter frame or similar device that moves the web-like layer in a lengthwise direction relative to the point of application of the polyurethane foam formulation and applies the polyurethane foam formulation to the moving web-like layer. A transverse dispensing head that moves back and forth across the width of the fibrous web layer can be used to distribute the polyurethane foam formulation over the web layer. The layer is easily mechanically pressed by passing it under rollers, between rollers, or under a doctor blade. The reticulated layer may be compressed to between 5% and 35% of its original thickness to force the individual fibers into contact with the polyurethane foam formulation. It is often useful to apply a protective film layer on top of the wetted web layer and then press it, or to apply a protective film layer on top of the wetted web layer while it is being pressed, so that the equipment used to press the film is not contaminated by the polyurethane foam formulation. Similarly, another protective film layer may be interposed between the mesh layer and the moving platform.

From about 1 to about 19 parts by weight, preferably from 1 to 9 parts by weight, and more preferably still from 2 to 5 parts by weight of the polyurethane foam formulation may be applied in this step, per part by weight of the reticulated layer.

The polyurethane foam formulation comprises at least one polyisocyanate, water, and at least one polyol having an equivalent weight of at least 500, and may also comprise other components, as described in more detail below. Polyurethane foam formulations of this type are highly reactive. Thus, the polyurethane foam formulation is at most only partially pre-formulated, wherein the polyisocyanate remains separated from water, polyol and other isocyanate-reactive compounds until immediately prior to dispensing. Once the polyisocyanate is mixed with water and polyol, the gelling and foaming reactions that form the foam begin to occur within a few seconds. The steps of applying the polyurethane foam formulation to the fibrous web layer and mechanically pressing the wetted fibrous web layer should be performed before the foaming and gelling reactions proceed to a significant extent. In most cases, these steps should be performed within 15 seconds of the time the polyisocyanate is in contact with the water and polyol in the polyurethane foam formulation. More preferably, these steps are performed within 10 seconds or 7 seconds of this time.

The components of the polyurethane foam formulation are cooled, then mixed together and the foam formulation is applied to the mesh layer. The components preferably each have a temperature of less than 15 ℃, more preferably 10 ℃ or less, when they are mixed. Any lower temperature is suitable provided that the components remain liquid and are not so viscous as to be difficult to process. It is generally not necessary to cool the components to below 0 ℃. This cooling slows the initial progress of the foaming and gelling reactions, thus prolonging the processing window for carrying out the application and wetting steps. Once the components are mixed and the foam formulation begins to react, an exothermic reaction occurs which will increase the temperature of the formulation. The temperature of the foam formulation when it first contacts the mesh layer should be no greater than 20 ℃, preferably no greater than 15 ℃ and still more preferably no greater than 12 ℃.

The wetted web layer is then gauged to a thickness of 0.25 to 1.0 inches. The exact thickness will depend on the particular product being made, as well as the desired product density. The regulation is conveniently carried out as follows: the wetted web layer is passed under a roller or blade, or between a pair of nip rollers, or more preferably, in a two-belt laminator preset to the desired thickness.

Once calibrated, the wetted web layer is heated to a temperature of 80 to 160 ℃ to cure the polyurethane foam formulation, thereby producing a cured and calibrated polyurethane foam cushion comprising 5 to 50 weight percent carded web. The gauge is maintained throughout the curing process at least until the foam formulation has cured completely such that the mat can maintain its gauge without the application of pressure and exhibits a closest curl set (measured below) of less than 10%. By "hold" gauge, it is meant that the wetted web layer is held under mechanical pressure so that its thickness is maintained at the desired value. This can be done, for example, by holding the wetted web layer between two heated platens for a desired time or, more preferably, by passing it through a dual belt laminator or similar equipment that allows for continuous production. The dual-belt laminator may have heated platens that provide the desired curing temperatures, or may be installed in an oven or other heating device.

Preferred curing temperatures are from 100 to 130 ℃. It may be necessary to ramp the temperature up over a period of time to balance the foaming and gelling reactions and in such a way that a good foam cell structure can be maintained.

The curing time should be as short as practical, since a shorter curing time means a faster operating speed and lower production costs. It is generally preferred that the components of the polyurethane foam formulation and the curing temperature are selected together such that the polyurethane foam formulation cures to a point where the product mat can retain its gauge without additional applied pressure and exhibits a closest curl set of less than 10% (measured as described below) within 10 minutes, and preferably within 5 minutes or less, from when the polyurethane foam formulation first comes into contact with the web. In a preferred process, wherein the wetted web layer is cured by passing it continuously through the gauge and heating apparatus, the line speed and length of the heating zone will be selected in conjunction with each other to provide sufficient time for curing to occur.

If desired, a decorative or functional pattern may be imprinted into the mat during the curing step.

The cured product is then suitable for winding (rolup), or can be transferred to other downstream operations. A variety of downstream operations are possible depending on the particular type of buffer product being made. For example, the separator that may be used in the manufacturing method may be removed for disposal or reuse. One or more additional layers may be attached to the mat using methods such as flame lamination, or gluing, or by some mechanical method. These additional layers may be, for example, enhancement layers; an isolation layer that allows the mat to be easily removed from the floor in a glue-down device; a carpet pile layer, synthetic grass layer or other type of display surface; water-proof layers, adhesive layers, etc. These additional layers may also be attached simultaneously during the preparation of the foam mattress by laying the mesh layer on top of the additional layer and performing the subsequent method steps of wetting, gauging and dispensing on top of the additional layer. Alternatively or in addition, a wet fiber mesh layer may be formed, and additional layers may be laid on top of the wet fiber mesh layer, either before or after the gauging step, but before the polyurethane foam formulation cures. It should be noted that because a good integral skin is typically formed over the product, there is typically no need to apply a water barrier material or other skin material, and because the embedded fibers provide good tear strength, the reinforcing layer can often be omitted from the product.

Other possible downstream operations include trimming, sizing (cutting) cutting into desired shapes (e.g., to prepare floor tile products), applying various topical treatments, etc.

In addition to these optional additional layers, the product mat typically has a bulk density of about 2.5 to 15 pounds per cubic foot (40-240 kg/m)³) Preferably 3 to 10 pounds per cubic foot (48-160 kg/m)³) And more preferably from 4 to 8 pounds per cubic foot (64-128 kg/m)³). The fiber content may be 5 to 50 weight percent%, more preferably 10 to 50% by weight, and still more preferably 16 to 33% by weight.

The mat products made according to the present invention and having the bulk density and fiber content as described above often have other desirable properties that make them suitable for a variety of floor covering applications. They often have a 50% compression set of less than 15%, measured at 70 ℃ according to the method described below. They often show an Indentation Load Deflection (ILD) of 25% of at least 14kPa, preferably at least 20kPa, at most 41pKa, measured according to the method described below. When subjected to simulated walk tests as described below, they often retain greater than 30% of their 25% ILD value and more typically greater than 50% of that value.

The polyurethane-forming mixture includes at least one organic polyisocyanate, which may be an aromatic, cycloaliphatic, or aliphatic isocyanate. Aromatic polyisocyanates are preferred, especially diphenylmethane diisocyanate (MDI) and/or polymethylene polyphenyl isocyanates (PMDI) are preferred, based on generally greater reactivity, availability and lower cost. MDI may be the 2,4 '-isomer, the 4, 4' -isomer, or some mixture thereof. PMDI is typically a mixture of one or more polymethylene polyphenyl isocyanates and some MDI; the MDI portion of the mixture may be either or both of the 2, 4-isomer and the 4, 4' -isomer. The prepolymer may be formed from any of the above polyisocyanates by reacting an excess of the polyisocyanate with a polyol, aminoalcohol or polyamine. A preferred type of prepolymer is described in EP485,953B. The polyisocyanate is generally used in an amount sufficient to provide an isocyanate index of about 0.85 to 1.5, preferably 0.9 to 1.25.

The polyurethane foam formulation also includes at least one polyol having an equivalent weight (per hydroxyl group) of at least 500. Two or more such polyols may be present. The equivalent weight of the polyol is preferably from about 750 to 3000, and more preferably from 1000 to 2000. The polyol should have an average of about 1.8 to 4 hydroxyl groups per molecule, preferably about 2 to about 3 hydroxyl groups. The polyol can have secondary or primary hydroxyl groups, or some combination thereof; however, it is preferred that at least 50% of the hydroxyl groups, and more preferably at least 80% of the hydroxyl groups, are primary hydroxyl groups, since these groups are more reactive towards isocyanate groups, thus allowing the formulation to cure faster. These polyols may be polyester polyols, polyether polyols, polyols prepared from vegetable oils and/or fatty acids, or other types. Polyether polyols are preferred, in particular polymers of propylene oxide containing 5 to 25% by weight of terminal poly (ethylene oxide) blocks.

One particularly preferred type of polyol is an amine-initiated polyol, which contains primarily primary hydroxyl groups, as described in USP6,762,274.

The polyurethane foam formulation also includes water, which reacts with the polyisocyanate to simultaneously generate blowing gas (carbon dioxide) and build molecular weight through the formation of urea linkages. Water is typically present in an amount of about 2 to about 7 parts by weight per 100 parts by weight of polyol having an equivalent weight of 500 or more. Preferred amounts are 3 to 6 parts, again based on 100 parts by weight of polyol equivalent of 500 or more.

In addition to the aforementioned polyisocyanates, polyols, and water, the polyurethane foam formulation may contain a variety of other components.

Preferably a catalyst is present. A variety of amine and organotin catalysts are suitable, including di-N-butyltin bis (isooctyl thioglycolate), dimethyltin dilaurate, dibutyltin diacetate, dibutyltin sulfide, stannous octoate, lead octoate, nickel acetylacetonate, iron acetylacetonate, bismuth carboxylate, triethylenediamine, N-methylmorpholine, similar compounds, and mixtures thereof. Amine-blocked (blocked) tin (IV) catalysts may be used, as described in U.S. patent No.5,491,174. The use of delayed action catalysts is generally undesirable in view of the need for rapid curing once the wetting step is complete. If an organometallic catalyst is used, it is generally present in an amount of from about 0.01 to about 0.5 parts by weight per 100 parts of the polyurethane foam formulation. If a tertiary amine catalyst is used, the catalyst is preferably present in an amount of from about 0.01 to about 3 parts of tertiary amine catalyst per 100 parts of polyurethane foam formulation, on a weight basis.

The polyurethane foam formulation may include at least one surfactant for stabilizing the foam expansion until the composition is cured. Silicone surfactants are preferred, such as those disclosed in U.S. patent No.4,483,894. If present, the surfactant typically comprises up to about 3 parts surfactant per 100 parts by weight polyol. However, one unexpected advantage of the present invention is that the surfactant can often be omitted, but still produce good quality foam with a reasonably uniform cell structure.

One or more crosslinkers (which refers to compounds having at least three isocyanate-reactive groups and an equivalent weight per isocyanate-reactive group of up to 499, preferably up to 250) may be present in the polyurethane foam formulation. A chain extender (which refers to a compound having exactly two isocyanate-reactive groups and an equivalent weight per isocyanate-reactive group of up to 499, preferably up to 250) may also be present. The crosslinking agent and the chain extender are generally used in a small amount, such as at most 20 parts by weight, preferably at most 5 parts by weight and more preferably at most 2 parts by weight, per 100 parts by weight of the polyol having an equivalent weight of 500 or more. Examples of suitable crosslinkers and chain extenders include triethanolamine, diethanolamine, monoethanolamine, glycerol, trimethylolpropane, pentaerythritol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1, 4-dimethylolcyclohexane, 1, 4-butanediol, 1, 6-hexanediol, 1, 3-propanediol, diethyltoluenediamine, amine-terminated polyethers such as Jeffamine D-400 available from huntsman chemical company, aminoethylpiperazine, 2-methylpiperazine, 1, 5-diamino-3-methyl-pentane, isophoronediamine, ethylenediamine, hexamethylenediamine, hydrazine, piperazine, mixtures thereof, and the like. The amine crosslinker and chain extender may be blocked, encapsulated, or otherwise made less reactive to reduce the initial reactivity of the formulation and provide more working time to apply and gauge the foam layer.

Polyurethane-foam formulations may include fillers, which reduce overall cost and may improve the flame retardancy, hardness, and other physical properties of the product. The filler may comprise up to about 50% of the total weight of the polyurethane foam formulation. Suitable fillers include talc, mica, montmorillonite, marble, barium sulfate (barite), milled glass granite, milled glass, calcium carbonate, aluminum trihydrate, carbon, aramid, silica-alumina, zirconia, talc, bentonite, antimony trioxide, kaolin, fly ash and boron nitride.

Other additives may be used, including flame retardants, pigments, antistatic agents, reinforcing fibers, antioxidants, preservatives, acid scavengers, and the like.

The cushioning product may be used as a carpet backing in a home, office, industrial, institutional or other environment. In this regard, it can be installed and used in the same manner as a conventional carpet cushion product. As noted above, the cushioning product may take the form of an additional cushion on the underside of the woven or tufted carpet product. The cushioning products are also useful in other cushioning and cushioning applications, including, for example, furniture cushions and various packaging applications.

Example 1

The formulated polyol mixture was prepared by: 1200 parts by weight of 1700 equivalents of a nominal trifunctional, amine-initiated polyol prepared according to the general method of U.S. Pat. No. 6,762,274, 12 parts of 85% diethanolamine in water, 43.7 parts water, and 18 parts of 33% triethylenediamine in dipropylene glycol are mixed. These were mixed thoroughly and cooled to 7 ℃.

Shredded post consumer carpet fibers (comprising predominantly nylon fibers having a length of about 8.5+/-4.8 cm) were carded and formed into 30.5X30.5 layers weighing 20.9 grams. The reticulated layer was sandwiched between two polyethylene barrier films and placed in a 30.5cm x1.11cm open mold preheated to 121 ℃. The mesh layer was heated in the mold for 30 minutes to remove residual water from the layer and cooled back to ambient temperature. The top barrier film layer was pulled back and a roller 4.5cm, 3500g, 30.4-cm in diameter was placed at one end of the open mold. 104.64g of the cooled polyol mixture were mixed with 66.08g of a cooled polyol mixture having a (7 ℃) isocyanate content of 29.4%PMDI product (SPECFLEX)^TMNE134 isocyanate, available from the dow chemical company) and 65g of the resulting polyurethane foam formulation was immediately poured onto a carded web in a mold. The release film was replaced and the drum was pulled down through a die on top of the release film, compressing the web and allowing the individual fibers to be wetted with the polyurethane foam formulation. The top was then placed on the mold, the mold was placed in a 121 ℃ oven, and the polyurethane foam formulation was cured for 5 minutes at 121 ℃. The mold was removed from the oven and the sample was removed. The samples were aged for 7 days under the conditions specified in ASTM3675-78 for performance testing. Density, compression set and sample thickness were measured according to ASTM 3675-78. ILD is determined according to ASTM 3574-78.

Compression set was measured as follows. The 2 "x 2" (5cmX5cm) foam samples were formed into 2 stacked samples, each about 1 inch (2.5cm) thick. The stack was placed in an Instron tensile testing apparatus equipped with a circular presser foot (pressofot) having an area of 1 square inch (6.45 cm)²) And the thickness of the sample is measured at 100 grams per square inch (100g/6.45 cm)²) Applied load measurement of (2).

The sample was then compressed between two parallel plates to 50% of its original thickness, each plate having an area greater than the area of the sample. The sample was then held at this compressed thickness and heated in a circulating air oven at 70 ℃ for 22 hours.

The sample was then removed from the oven and allowed to re-expand. It was returned to the oven for 0.5 hours and then allowed to cool for 5 to 10 minutes. The thickness was then re-measured as above. Compression set is calculated as follows

C_f=100(t_o-t_f)/t_o

Wherein C is_fFor compression set, t_oIs an initial thickness, t_fIs the final sample thickness.

Ball rebound was determined according to astm d3574-86 test method H, with the exception that the sample size was modified to 2X6 inches (2.5X15cm) and the sample height was superimposed to about 1 inch (2.5cm) by stacking multiple layers of the composite.

The 25% ILD was measured as follows. Enough samples of 2 "X6" (2.5X15cm) cut composite were stacked to form a stack of stacked samples, each about 1 inch (2.5cm) thick. The stack was placed in an Instron tensile testing apparatus equipped with a circular press foot having an area of 1 square inch (6.45 cm)²) And the thickness of the sample is measured at 100 grams per square inch (100g/6.45 cm)²) Applied load measurement of (2). The sample was compressed to 75% of its original thickness using a 1 square inch press foot and the load required to so compress the sample was determined. This reading is the pressure resistance of the foam. This step was repeated on the same stack and the results averaged.

The retention of 25% ILD was determined as follows. The 25% ILD was measured on the samples as described above. The samples were then subjected to 12,000 compression cycles on a Hexapod testing machine, which simulates repeated walking on the samples, and the 25% ILD was re-measured as above. The retention of 25% ILD was calculated as the percentage of the second 25% ILD measurement as the initial 25% ILD measurement.

The results of the above tests are shown in table 1. A comparison is given of the properties of commercially available rebind carpet backing products.

TABLE 1

Properties of	Example 1	Commercially available recombined carpet backings
			Curing time, min.	5	NA

Sample weight, g/m2	1016	1098
			The fiber content after consumption%	22	0
Density of mat in kg/m3	80.4	96.4
			Thickness, mm	12.6	11.3
25%ILD，kPa	25.5	22
			50% compression set%	15	14
Rebound of the ball%	41	30
			25% ILD retention%	60	54

The data in table 1 shows that example 1 has ILD, compression set, and ball rebound values very close to the commercial recombined material even though the density and mat weight of example 1 are low, and even though example 1 contains a significant amount of post-consumer fiber content. The ILD retention of example 1 was also better than the commercial recombined material.

The mat has a good uniform pore structure and good properties despite the absence of surfactant.

Example 2

Example 1 was repeated, using the polyol mixture formulated below instead of the mixture described in example 1:

the conditions were the same as in example 1, except that the mold temperature was only 100 ℃.

The properties were measured as in the examples and the results are shown in table 2:

TABLE 2

Properties of

Example 1

Curing time, min.	5
		Sample weight, g/m2	997
The fiber content after consumption%	28
		Density of mat in kg/m3	72.4
Thickness, mm	12.7
		25%ILD，kPa	15.1
50% compression set%	15
		Rebound of the ball%	35.7
25% ILD retention%	77.5

Claims (8)

1. A method of making a foamed polyurethane floor covering product comprising a cured and gauged polyurethane foam cushion comprising from 5 to 50 weight percent fibers, the method comprising:

a) forming a mesh layer comprising at least 30 wt% fibers such that the mesh layer has a weight of 150 to 660g/m²And has a thickness of 0.25 to 1.0 inch, and the fibers in the mesh layer have an average length of 0.75 to 40 cm;

b) continuously applying to the web-layer a cooled polyurethane foam formulation comprising at least one polyisocyanate, water and at least one polyol having an equivalent weight of at least 500, the temperature of the cooled polyurethane foam formulation when applied to the web-layer being no more than 15 ℃, and pressing the web-layer and applied polyurethane foam formulation together to between 5% and 35% of the original thickness of the web-layer to mechanically wet out the fibers in the web-layer; then the

c) Gauging the thickness of the wetted reticulated layer to 6.35 to 25.4mm (0.25 to 1.0 inch) while maintaining the gauge, heating the polyurethane foam formulation to a temperature of 80 to 160 ℃ to cure the polyurethane foam formulation, thereby producing a cured and gauged polyurethane foam cushion comprising 5 to 50 wt.% fibers.

2. The method of claim 1, wherein the temperature of the cooled polyurethane foam formulation when applied to the reticulated layer does not exceed 10 ℃.

3. The method of any of the preceding claims, wherein the mesh layer comprises at least 50 wt% fibers.

4. The method of any of the preceding claims, wherein the mesh layer comprises carded fibers.

5. The method of any of the preceding claims, wherein the fiber is obtained from a post-consumer carpet product.

6. The method of any of the above claims, wherein the foamed polyurethane floor covering product has a density of 3 to 10 pounds per cubic foot (48-160 kg/m)³)。

7. A foamed polyurethane floor covering product prepared by the process of any of claims 1-6.

8. The product of claim 7 comprising 5 to 30 weight percent fiber.