Spill resistant carpet backing

Details Spill resistant carpet backing Spill resistant carpet backing

2001-02-08

2004-06-01

Niland, Patrick D. (Department: 1714)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

At least one aryl ring which is part of a fused or bridged...

C428S032000, C428S085000, C428S094000, C428S095000, C428S096000, C428S097000, C523S200000, C523S210000, C524S276000, C524S284000, C524S394000, C524S499000, C524S591000, C524S839000, C524S840000

Reexamination Certificate

active

06743844

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a spill resistant carpet backing. More particularly, it relates to using a hydrophobic acid-treated inorganic filler or salts thereof as part of an aqueous dispersed polymeric composition to increase the spill resistance of a carpet backing.
DESCRIPTION OF THE PRIOR ART
Generally, tufted carpets minimally consist of tufted fibers through a primary backing and a precoat. Tufted carpets have a precoat and may also have additional layers such as a laminate layer, a secondary layer, and a foam layer. Moreover, the tufted carpet may have more than one secondary layer. The tufted carpet may be applied to a variety of subfloors, including wood, concrete, and tile.
The precoat is required to anchor the carpet tufts to the primary backing. It may also contain an adhesive to adhere the tufted carpet to additional layers or the subfloor. The precoat can affect the carpet's tuft bind, hand, delaminating properties, wet strength properties, wear resistance, and barrier performance. Alternatively, a laminate layer may be applied without a precoat and anchor the carpet tufts to the primary backing. But, better anchoring is achieved when a precoat is applied than with a laminate layer is applied alone.
The precoat may be prepared from several materials. However, it is usually prepared from a polyurethane material or a styrene-butadiene latex. It may be prepared from a butadiene-acrylonitrile latex, an ethylene-vinyl acetate latex, a styrene-butadiene-butyl acrylate latex, a chloroprene latex, a polyethylene copolymer latex, an ethylene-styrene latex, a styrene-butadiene-vinylidene chloride latex, a styrene-alkyl acrylate latex, a vinyl latex, or an acrylic latex.
With regard to a polyurethane precoat, conventional practice in the carpet manufacturing industry requires that the precoat be prepared from an isocyanate formulation (A-side formulation) and a polyol formulation (B-side formulation) at the carpet manufacturing site. This is sometimes referred to as “A+B chemistry”. Preparing a polyurethane precoat by A+B chemistry can result in unpredictable loss of production and inefficiency due to problems that can occur in carrying out the reaction at the manufacturing site, such as premature gellation.
Alternatively, the polyurethane precoat may be applied as an aqueous polyurethane (PU) dispersion. Aqueous PU dispersions can be prepared by polymerizing the polyurethane reactants in an organic solvent followed by dispersion of the resulting solution in water, and optionally followed by removal of organic solvent. See U.S. Pat. Nos. 3,437,624; 4,092,286; 4,237,264; 4,742,095; 4,857,565; 4,879,322; 5,037,864; and 5,221,710, which are incorporated herein by reference. Also, an aqueous polyurethane dispersion may be prepared by first forming a prepolymer, next dispersing the prepolymer in water, and finally conducting a chain extension in the water as disclosed in WO 98/41552, published Sep. 24, 1998, which is incorporated herein by reference. Preparations of aqueous dispersions of polyurethane are also described in U.S. patent application Ser. Nos. 09/039,978 and 09/039,976. U.S. Pat. No. 4,296,159 to Jenkines, et al., discloses preparing a tufted or woven article having a unitary backing prepared by applying a polyurethane forming composition to the underside of the tufted or woven article.
The precoat may consist of an aqueous styrene butadiene latex. Styrene-butadiene (SB) latexes for use in carpet are described, for example, in P. L. Fitzgerald, “Integral Latex Foam Carpet Cushioning”, J. Coat Fab. 1977, Vol. 7 (pp.107-120); and in R. P. Brentin, “Latex Coating Systems for Carpet Backing”, J. Coat. Fab. 1982, Vol. 12 (pp. 82-91). SB latexes provide flexibility in production costs owing to the ability to include low to high concentrations of filler component in a low viscosity latex. However, SB latexes with filer may not, meet the rigorous standards set for intermediate grade carpets. In addition, current technology may require that a latex material remain stable for a period of up to one year. High solids content affects the stability of SB latexes. Accordingly, commercially available SB latexes typically do not have a solids content of greater than 55%.
Without regard to the type of material used to make the precoat, a liquid spill can detrimentally affect the carpet's performance and appearance. The liquid can flow through the precoat and then onto, or be absorbed by, the underside of the carpet. In particular, spilled liquids such as beverage drinks, food, blood, urine, and feces can penetrate to the underside of the carpet or into the subfloor so that the liquids can be inaccessible by various cleaning methods.
When the precoat is an aqueous polymeric dispersion, various conventional methods are used to provide a moisture or spill resistant barrier between the primary backing and other layers or the subfloor. The conventional methods include (1) modifying the precoat formulation, (2) adding an essentially impermeable membrane between the precoat and the other layers or the subfloor, and (3) applying a spill resistant coating onto the precoat or another layer.
An example of an attempt to improve spill resistance by modifying the precoat formulation is increasing the coating weight of the dispersion. This method is undesirable because it requires more material, which is expensive. It can also yield a final carpet having undesirable hand or stiffness properties. Moreover, the precoat has an increased probability of blistering in the drying ovens.
Another example of an attempt to improve spill resistance by modifying the precoat formulation is adding a wax filler to the dispersion. While the addition of waxes to aqueous styrene-butadiene latexes is known to improve the water barrier properties of the precoat, it is also known that wax additives are generally detrimental to other carpet properties.
Another example of a formulation modification is the reduction of filler levels. But, this formulation change increases the carpet cost and may increase the tendency of the precoat to blister in the drying ovens.
Examples of an attempt to improve spill resistance by adding an essentially impermeable membrane between the precoat and the other layers or the subfloor are described in U.S. Pat. Nos. 4,336,089 and 5,763,040. In U.S. Pat. No. 4,336,089; the patentees describe a water-impervious film that collects the spilled liquid below the carpet surface. In U.S. Pat. No. 5,763,040, the patentees describe applying a non-permeable fabric or film to a carpet backing. This secondary backing prevents liquid flow to subsequent layer or to the subfloor. Unfortunately, both described membranes may permit the spilled liquid to collect at a depth between the carpet and the underlay barrier such that the spilled liquid cannot be removed through traditional cleaning methods.
An example of an attempt to improve spill resistance by applying a spill resistant coating is applying a fluorochemical or another material onto the precoat or another layer. U.S. Pat. No. 5,348,785 describes applying a fluorochemical on the underside of a secondary backing. The use of fluorochemicals to impart water impermeability is also described in U.S. Pat. Nos. 4,619,853 and 4,643,930. Unfortunately, the use of fluorochemicals can increase the cost of the carpet. Additionally, steam or extraction cleaning of a carpet can leach the fluorochemicals out of the carpet.
Other materials that are applied as a spill resistant coating include silicone-based compositions, wax emulsions, naturally occurring oils, and hydrophobic acrylate resins. Applying these various hydrophobic compositions to a secondary backing is described in U.S. Pat. No. 5,558,916, but these compositions do not prevent absorption of spilled liquids by underlying layers.
It would be desirable to prepare a carpet backing that resists penetration by spilled liquids. It would also be desirable to prepare the carpet backing by a process that would not significantly increase the cost of manufacturing the carpet.

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