Sodium silicate coating process and products incorporating same

Details Sodium silicate coating process and products incorporating same Sodium silicate coating process and products incorporating same

2002-01-30

2004-03-16

Juska, Cheryl A. (Department: 1771)

Stock material or miscellaneous articles

Pile or nap type surface or component

Particular backing structure or composition

C428S096000, C428S448000, C427S397700, C427S397800, C427S402000

Reexamination Certificate

active

06706362

ABSTRACT:

FIELD OF INVENTION
The present invention relates generally to textile products, and, more specifically, to carpet products having an attached layer of polyurethane.
BACKGROUND OF THE INVENTION
The majority of all tufted carpet is manufactured today by tufting a carpet yarn into a synthetic primary backing material. Typically, the primary backing material is a woven flat strand polypropylene material and is passed through a tufting machine where yarn elements are stitched through this primary backing material. Following this tufting operation, a coating of latex material is applied to the back of the yarn loops to anchor the yarn elements in place in the backing, add dimensional stability to the carpet, and provide a smooth undersurface for the carpet. Examples of carpet back coating processes are disclosed in U.S. Pat. Nos. 4,217,383 and 4,632,850.
Polyurethane compositions are well known in the art. Cellular polyurethane, such as foamed or frothed polyurethane, is used for items such as integrally attached cushions for carpet. A method of attaching a cellular polyurethane cushion to a carpet backing is shown in U.S. Pat. No. 4,512,831. Non-cellular polyurethane or polyurethane elastomers can be used for items, such as carpet tiles. A carpet tile using polyurethane elastomers is disclosed in U.S. Pat. No. 5,159,012.
Sometimes there are problems associated with adhering a polyurethane cushion, either cellular or non-cellular, to a carpet backing with a back coating of a polymer, such as styrene-butadiene. Therefore, a need exists for a system for reliably adhering a polyurethane coating to a back-coated carpet product.
SUMMARY OF THE INVENTION
The present invention satisfies the above-described needs by providing a sodium silicate layer intermediate a polymer-coated carpet backing and an attached polyurethane layer. The carpet product of the present invention comprises a primary backing tufted with yarn to form a face pile on one side of the backing and loop backs on the other side of the backing. A polymer coating on the other side of the backing secures the loop backs thereto. A layer of silicate is formed on the polymer coating and a layer of polyurethane is disposed on the layer of silicate.
In an alternate embodiment, the present invention comprises a method of making a carpet product. The method comprises applying a layer of silicate to a polymer-coated carpet backing, curing the layer of silicate, applying a layer of polyurethane to the cured layer of silicate, and curing the layer of polyurethane.
Accordingly, it is an object of the present invention to provide an improved carpet product and an improved method of making a carpet product.
Another object of the present invention is to provide an improved bond between a polymer-coated carpet back and a polyurethane layer.
A further object of the present invention is to provide a reliable method of attaching a polyurethane layer to a carpet product.
These and other objects, features and advantages of the present invention will become apparent after a review of the following detailed description of the disclosed embodiments and the appended claims.
DETAILED DESCRIPTION OF THE DISCLOSED EMBODIMENTS
The present invention relates to carpet products and the method of their manufacture. Typically, a tufted pile carpet is made from a primary backing material, such as a woven flat strand polypropylene material, that is passed through a tufting machine where yarn elements are stitched through the primary backing material. Following this tufting operation, a coating of a polymer, usually a latex polymer, is applied to the back of the yarn loops to anchor the yarn elements in place in the primary backing material. Examples of primary carpet backing material coating processes are disclosed in U.S. Pat. Nos. 4,217,383 and 4,632,850, the disclosures of which are incorporated herein by reference.
Polymers that are used to coat the primary carpet backing material and that are the subject of the present invention are those polymers that tend to be neutral, acidic or have acidic moieties attached thereto. Such polymers have a pH of 8.1 or lower. Examples of such polymers include, but are not limited to, styrene-butadiene rubber, ethyl vinyl acetate, and acrylics.
It is also typical in making carpet products to attach a layer of polyurethane to the polymer-coated primary carpet backing material. Polyurethane compositions in accordance with the present invention may be solid or cellular, i.e., foamed or frothed, rigid or flexible. The particular composition of the polyurethane-forming components is not a critical aspect of the present invention. A method of attaching a cellular polyurethane cushion to a carpet backing is shown in U.S. Pat. No. 4,512,831, the disclosure of which is incorporated herein by reference. A carpet tile using polyurethane elastomers is disclosed in U.S. Pat. No. 5,159,012, the disclosure of which is incorporated herein by reference.
Polyurethane is a polymerization product of a polyol component, an isocyanate component, water (optional) and a catalyst system that promotes a polymerization reaction between the isocyanate component and the polyol component to form the polyurethane. Conventional practice in the art is to form an isocyanate mixture, referred to as SIDE A; and to form a mixture of polyols, chain extenders, cross-linking agents, fillers, blowing agents, surfactants, catalysts etc., commonly referred to as SIDE B. The SIDE A component and the SIDE B component are mixed together at a desired ratio to form the polyurethane polymer. See U.S. Pat. No. 5,159,012 the disclosure of which is incorporated herein by reference.
The polyol component may contain either a single polyol or a mixture of two or more polyols. The specific polyols useful in the manufacture of polyurethane elastomers are well known in the art and include aliphatic, alicyclic and aromatic polyols. More specifically, the polyol component useful in this invention has an average functionality within the range of 1.7-8, preferably within the range of 2-3, and an average molecular weight of from about 900 to about 9000, preferably from about 1000 to about 6000. The polyol component may contain isomeric and polymeric polyols. Additionally, the polyol component has a hydroxyl number of less than about 150, preferably less than about 115.
The preferred polyols suitable for use in this process are ethylene glycol; diethylene glycol; propylene glycol; dipropylene glycol; glycerin; sucrose; butylene glycol; polyether polyols derived from ethylene oxide, propylene oxide, and mixtures of such oxides; polyether polyols derived from propylene oxide and capped with ethylene oxide; polyethylene glycol; polypropylene glycol; polybutylene glycol; 1,2-polydimethylene glycol; polydecamethylene glycol and mixtures of the above polyols.
The polyurethane composition can be either foamed or unfoamed. In those instances where foaming is desired, such can be accomplished by using an inert gas frothing technique, a volatile liquid blowing agent technique, a chemically blown (water) technique or combinations thereof, in conjunction with a surface active agent, such as the commercially available block polysiloxane-polyoxyalkylene copolymers.
Chemical blowing of the polyurethane composition, if desired, is effected by controlling the catalyst system, the water concentration and the isocyanate level. Generally, water is present in the reaction mixture from between approximately 0.01 to 5.0 parts per hundred parts of polyol, preferably between 0.1 parts and 2 parts, over and above the water normally present in the reaction mixture. The catalyst system not only must effect rapid curing but also must control formation of carbon dioxide resulting from the reaction of water and isocyanate. Blowing should be controlled to effect expansion between about 5% and 200%, preferably between approximately 7% and 100%, so that a carpet yarn loop back stitch is saturated with reactants and the reactants expand sufficiently prior to curing. Suitable catalysts are those which promote polyuretha

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