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...
Reexamination Certificate
1999-12-14
2003-02-11
Seidleck, James J. (Department: 1711)
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...
C524S555000, C524S828000, C428S304400, C428S308400
Reexamination Certificate
active
06518348
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to carpet backings. More particularly, it relates to aqueous dispersed polymeric compositions containing a hydrophobically-modified ethylene-oxide-based urethane block copolymer as a thickener and a method for preparing a carpet backing therefrom.
DESCRIPTION OF THE PRIOR ART
Carpet processing depends on the rheological properties of the carpet's various layers. Thickeners are added to affect those Theological properties. Unfortunately, the industry standard thickener is a sodium polyacrylate that adversely affects finished carpet tuftbind and water barrier properties. Accordingly, there is a need for a thickener that imparts excellent carpet processing properties without adversely affecting finished carpet tuftbind and water barrier properties. This need particularly applies to tufted carpets.
Generally, tufted carpets minimally consist of tufted fibers through a primary backing and a precoat. Tufted carpets 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 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. However, better anchoring is achieved when a precoat is also applied than when a laminate layer is applied alone.
Precoat, laminate, and foam layers may be prepared from a butadiene-acrylonitrile latex, an ethylene-vinyl acetate latex, a styrene-butadiene-butyl acrylate latex, a polychloroprene 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. However, they are usually prepared from a polyurethane material or a styrene-butadiene latex.
With regard to polyurethane layers, conventional practice in the carpet manufacturing industry requires that a polyurethane layer 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 layer by A+B chemistry requires a substantial investment in specialized equipment to achieve the exceptional performance characteristics of this method.
Alternatively, the polyurethane layer 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. In this instance, the aqueous polyurethane dispersion will preferably have water as a continuous phase. 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.
As a polyurethane dispersion, the polyurethane layer may be applied as a blown formulation. The blown formulation is generally prepared by mixing the A-side components with the B-side components in the presence of a gas, which is either mechanically introduced or chemically produced, to form bubbles that yield a cell-like structure in the cured polyurethane. Mechanical whipping of gas into a polyurethane formulation is also termed “frothing.”
The industry standard sodium polyacrylate thickener improves the rheological properties of carpets prepared with aqueous dispersed polymeric compositions. Unfortunately, it also adversely affects the carpet's tuftbind and water barrier properties. Accordingly, it is desirable to use a thickener that imparts similar Theological properties without adversely affecting the finished carpet's tuftbind and water barrier properties.
SUMMARY OF THE INVENTION
According to the present invention, an aqueous dispersed polymeric composition for preparing a carpet backing is provided. In the preferred embodiment, the aqueous dispersed polymeric composition comprises an aqueous dispersed polymeric material and a hydrophobically-modified ethylene-oxide-based urethane block copolymer. In the more preferred embodiment, the aqueous dispersed polymeric material is an aqueous polyurethane dispersion composition. Moreover, a method for preparing a carpet backing using the aqueous dispersed polymeric composition is provided.
DESCRIPTION OF THE INVENTION
In the preferred embodiment, the aqueous dispersed polymeric composition for preparing a carpet backing comprises an aqueous dispersed polymeric material and a hydrophobically-modified ethylene-oxide-based urethane block copolymer as a thickener. The aqueous dispersed polymeric material is selected from the group consisting of an aqueous polyurethane dispersion composition, a styrene-butadiene latex, a butadiene-acrylonitrile latex, an ethylene-vinyl acetate latex, a styrene-butadiene-butyl acrylate latex, a polychloroprene latex, a polyethylene copolymer latex, an ethylene-styrene latex, a styrene-butadiene-vinylidene chloride latex, a styrene-alkyl acrylate latex, a vinyl latex, an acrylic latex, and mixtures thereof. In the more preferred embodiment, the aqueous dispersed polymeric material is an aqueous polyurethane dispersion composition.
In the present invention, polyurethane can refer to a polyurethane compound, a polyurea compound, or mixtures thereof. A polyurethane compound can be obtained by the reaction of a polyol with a polyisocyanate. A polyurea compound can be obtained by the reaction of an amine with a polyisocyanate. A polyurethane compound or polyurea compound can contain both urea and urethane functionality, depending on what compounds are included in the A and/or B-side formulations. For the purposes of the present application, no further distinction will be made herein between the polyurethane compounds and polyurea compounds. The term “polyurethane” will be used generically to describe a polyurethane compound, a polyurea compound, and mixtures thereof.
An aqueous polyurethane dispersion composition useful in the practice of the present invention includes water, and a polymeric compound selected from the group consisting of a polyurethane compound, a mixture of polyurethane-forming compounds, and mixtures thereof. Preferably, the aqueous polyurethane dispersion composition will have water as a continuous phase. Polyurethane-forming compounds as used in the present invention are compounds that are capable of forming polyurethane polymers. Polyurethane-forming compounds include, for example, polyurethane prepolymers. Prepolymers useful in the practice of the present invention are prepared by the reaction of active hydrogen compounds with any amount of isocyanate in excess material relative to active hydrogen material. The isocyanate functionality can be present in an amount of from about 0.2 wt % to about 40 wt %. A suitable prepolymer can have a molecular weight in the range of from about 100 to about 10,000. Prepolymers useful in the practice of the present invention should be substantially liquid under the conditions of dispersion.
Active hydrogen compounds can be described as compounds having functional groups that contain at least one hydrogen atom bonded directly to an electronegative atom such as nitrogen, oxygen or sulfur. Suitable active hydrogen compounds can b
Jenkines Randall C.
Lee Si-Ho
Suarez Rhonda R.
Tabor Rick L.
Asinovsky Olga
Dow Global Technologies Inc.
Seidleck James J.
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