Stock material or miscellaneous articles – Pile or nap type surface or component – Composition of pile or adhesive
Reexamination Certificate
2000-02-22
2003-01-07
Juska, Cheryl A. (Department: 1771)
Stock material or miscellaneous articles
Pile or nap type surface or component
Composition of pile or adhesive
C428S095000, C428S096000, C428S523000, C427S374400, C427S389900
Reexamination Certificate
active
06503595
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to carpet backing compositions. More particularly, the present invention relates to extruded carpet backing materials used to provide a durable, highly flexible carpet backing capable of being thermoformed. Still more particularly, the present invention relates to carpet constructions, preferably including a tuft, means, such as a scrim, for retaining the tuft, and an extruded thermoplastic barrier coating as the carpet backing therefor.
While carpets are generally manufactured by a number of methods, processes such as tufting and needle punching have become quite popular in the last few years. In particular, the majority of carpeting manufactured today is produced by the tufting process. Tufted carpets are composite structures in which the face fiber forming the pile, i.e., the surface of the carpet, is needled through a primary backing and the base of each tuft extends through the primary backing and is exposed on the bottom surface of the primary backing.
The basic manufacturing approach to the commercial production of tufted carpeting is to start with a woven scrim or primary carpet backing and to feed this into a tufting machine or a loom. The carpet face fiber is needled through and embedded in the primary carpet backing thus forming a tufted base or griege goods. Griege goods are typically backed with an adhesive coating in order to secure the face fiber to the primary backing. In order to reduce costs, some carpet often receives only a latex adhesive coating as the backing. Higher cost carpet often receives both a secondary backing and a latex adhesive coating.
The application of the latex adhesive coating involves preparing griege goods by stitching a primary carpet backing material with face fiber in a manner so as to form on the top surface of the material a pile composed of numerous closely spaced, up-standing loops of yarn. Thereafter, the bottom surface of the thus formed griege goods is coated with a latex polymer binder such as a styrene-butadiene copolymer. The coated griege goods are then passed through an oven to dry the latex adhesive coating to bond the face fibers to the primary backing which causes the bonding of and which is the principal reason for adding the latex binder.
In another method, such tufted carpets have been manufactured by processes which generally comprise composite structures in which tufts, or bundles of carpet fibers are introduced (such as by stitching) into a primary backing or scrim, such as a woven or non-woven fabric. A secondary backing or coating of thermoplastic material is then applied to the underside of the carpet construction in order to securely retain the tufted material in the primary backing. This secondary backing not only dimensionally stabilizes this construction but also provides greater abrasion and wear resistance, and serves as the adhesive for the barrier coating.
The face fiber or yarn used in forming the pile of a tufted carpet is typically made of any one of a number of types of fiber, such as nylon, acrylics, polypropylene, polyethylene, polyamides, polyesters, wool, cotton, rayon and the like.
Primary backings for tufted pile carpets are typically woven or non-woven fabrics made of one or more natural or synthetic fibers or yarns, such as jute, wool, polypropylene, polyethylene, polyamides, polyesters, and rayon. Films of synthetic materials, such as polypropylene, polyethylene and ethylene-propylene copolymers may also be used to form the primary backing.
Likewise, secondary backings for tufted pile carpets are typically woven or non-woven fabrics made of one or more natural or synthetic fibers or yarns. Preferably, secondary backings for tufted pile carpets are open weave or leno weave, i.e., tape yarn in the warp direction and spun staple fiber in the fill direction. The spun staple fiber is more costly but desirable to increase adhesion between the backing and the latex adhesive.
Another commercially important carpet manufacturing process is needle punching. In this process the carpet fibers are punched by a series of barbed needles, which causes them to mechanically interlock and form a non-woven loose fabric structure. In the known processes, the problem of fiber loss is always present. In most cases, a back coating is employed to reduce fiber loss and to also provide dimensional stability and body. The problem of such fiber loss is particularly acute in connection with automotive carpeting where wear is generally concentrated into limited areas. Automotive carpet is subjected to sliding and other forces, which have resulted in excessive fiber loss therein.
The method utilizing a latex polymer binder for making carpet is used in 80 to 90% of all carpet made in the United States. This carpet-making method has disadvantages in that it requires a drying step and thus an oven to dry the latex polymer binder. The drying step increases the cost of the carpet and limits production speed. Furthermore, it has recently been reported that latex adhesive compositions may generate gases that may be the cause of headaches, watery eyes, breathing difficulties and nausea, especially when used in tightly sealed buildings. See Herligy, The Carpet & Rug Industry, October 1990. In addition, overheating of the carpet may occur during drying of the latex, which in turn may affect the shade, or color of the carpet.
Consequently, carpet manufacturers have been attempting to develop a new approach for the preparation of tufted carpets. One new approach is the preparation of tufted carpets with a hot-melt adhesive composition instead of a latex composition.
Hot-melt adhesives are amorphous polymers that soften and flow sufficiently to wet and penetrate the backing surfaces and tuft stitches of carpets upon application of sufficient heat. Furthermore, hot-melt adhesives tend to adhere to the backing surfaces and/or tuft stitches. That is, hot-melt adhesives stick to backing surfaces and tuft stitches.
By the use of hot-melt adhesive, the necessity of drying the composition after application is eliminated and further, when a secondary backing material is desired, it can be applied directly after the hot-melt composition is applied with no necessity for a drying step.
Application of a hot-melt composition is generally accomplished by passing the bottom surface of the griege goods over an applicator roll positioned in a reservoir containing the hot-melt composition in a molten state. A blade is ordinarily employed to control the amount of adhesive which is transferred from the application roll to the bottom surface of the structure. After application of the hot-melt composition to the bottom surface of the griege goods, and prior to cooling, the secondary backing, if desired, is brought into contact with the bottom surface, and the resulting structure is then passed through nip rolls and heated.
The activation temperature of a hot-melt adhesive, i.e., the temperature at which the adhesive softens and flows sufficiently to wet and penetrate the backing surfaces and tuft stitches, is below the temperature at which the backing and face yarns melt or otherwise distort. Otherwise, the backing and face yarns may suffer other damage due to heating.
Hot-melt adhesives also must have low enough viscosities at temperatures employed in finishing to achieve good wetting of the backings and sufficient encapsulation of tuft stitches to make the tuft yarns resistant to pull-out, pilling and fuzzing. In addition, for commercial practice, economics of a carpet manufacturing process utilizing hot-melt adhesive must be at least as good as those of conventional latex lamination techniques which remain the dominant lamination process in commercial carpet manufacture.
A number of hot-melt adhesives and processes using the hot-melt adhesive have been proposed for use in carpet lamination. For example, U.S. Pat. No. 3,551,231, issued Dec. 29, 1970 to Smedberg, discloses a hot-melt adhesive carpet lamination process in which molten adhesive consisting of an ethylene-vinyl acetate copolymer and, o
Elliott Sharon Jones
Kim Se-hyun
Aristech Chemical Company
Juska Cheryl A.
Roberts Abokhair & Mardula LLC
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