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TENSION FLOOR COVERING WITH
FIELD OF THE INVENTION 5
The invention relates to vinyl surface coverings. In particular, the invention is directed to tension floor coverings having a reinforcing layer.
BACKGROUND OF THE INVENTION 10
A considerable body of knowledge has developed on vinyl flooring materials and reinforcement materials for such flooring. Reinforcing layers, and more commonly, glass reinforcing layers, have received increasing attention in recent years for the construction of surface cov- 15 erings. Floor coverings, in particular, have employed glass reinforcing layers, although the majority of the products which have contained such reinforcing layers have been developed in Europe. The reason for this appears to be that European dwellings are constructed 20 primarily on concrete slabs which are dimensionally stable. These reinforced floor coverings have been loose-lay floor coverings which have been adequate for the substantially dimensionally stable European subfloors. 25
In the U.S., however, substantially different methods of construction are used whereby most structures contain suspended wooden subfloors, including particleboard and plywood. Although structures of this type are less expensive than those containing concrete floor- 30 ing, suspended wooden subfloor is less stable than concrete when subjected to humid summer/dry winter seasonal changes. Self-induced tension floorings have been developed for these less stable subfloors. However, no tension flooring has had a reinforcing layer. 35 This is because reinforcing layers of the prior art were used to obtain dimensional stability and therefore, did not permit elongation of the surface covering.
Swart U.S. Pat. No. 2,800,428 entitled "Molded Article of Stretchable Glass Cloth" provided a concept of 40 patterned cuts in a plastic sheet or glass cloth so that the sheet or cloth can be stretched and adapted for fitting compound curves without any need for cutting special patterns. There is no suggestion in Swart of placing the cloth in a pre-stressed condition or any advantage to use 45 such a glass cloth over a substantially planar surface as the subfloors of the present invention.
Siddall U.S. Pat. No. 8,297,461 entitled "Reinforced Plastic Sheeting" disclosed how segmented inextensible filaments such as glass fibers encapsulated in polyvinyl 50 chloride (PVO) can produce sheets capable of being stretched or compressed a small amount in any direction and any one portion of the sheet can be stretched or compressed without affecting any other portion so that the sheet could be used as flashing on a roof. Siddall 55 teaches use of annealed metal filaments so that when deformed they have no memory and therefor no tendency to return to their original shape.
Deichert et al. U.S. Pat. No. 3,464,178 teaches a method of installing resilient sheet flooring having a 60 porous backing and a thermoplastic resin layer which shrinks in both the machine direction and across machine direction by bonding the backing layer of the sheet flooring to the perimeter of the room and to each other. 65
Evans U.S. Pat. No. 3,990,929, which is incorporated by reference, teaches methods of manufacturing and installing self-induced tension flooring or surface cover
ing by manufacturing the structure on a thermally dimensionally stable backing. The backing not only serves as a carrier on which the flooring is manufactured but the backing also remains with the surface covering and is removed just prior to installation at the job site. The surface covering is secured at its perimeter only before the stresses therein are relieved.
Evans U.S. Pat. No. 4,159,219 teaches a method to produce an unbacked tension flooring by the specific design of two or more thermoplastic layers constructed such that when rolled, the outward facing layer elongates and the inward facing layer is compressed. Upon unrolling and placing flat, the elongated layer overcomes the compressed layer and thus a length greater than the original length before roll-up is generated. This elongation is defined herein as "roll-up growth". On securing the surface covering only at its periphery shortly after unrolling, the tendency of the surface covering to return to its original dimension, i.e. its elastic memory, creates a self-induced tension therein.
Greiner, Jr. et al. U.S. Pat. No. 4,135,675 shows a paper carrier stripping method and stripping apparatus which prevents uncontrolled tension from the necessary procedure of removing a strippable carrier from the structure before placing into a roll upon a windup stand.
Installation of these elongated tension floors by attachment at their periphery has produced one of the most reliable installation methods to accommodate fluctuating dimensional changes of unstable wood subfloors in today's environment. However, such tension floors are deficient in that the tension required to elongate the surface covering sufficiently to accommodate change of wooden subfloors may be excessive. Further, the elongation of the surface covering is typically only in one direction.
Eckert et al. U.S. Pat. No. 4,654,244 entitled "LooseLay and Adhered Surface Coverings" teaches the insitu modification of reinforcing layers to form a surface covering capable of accommodating the movement of very unstable subfloors such as particle board. One requirement of loose-lay flooring is that it must lay flat upon the subfloor and not curl or dome after installation. These loose-laid structures were balanced to provide lay-flat in-service characteristics.
SUMMARY OF THE INVENTION
In one embodiment, the invention provides a resilient floor covering comprising a reinforcing layer having regions of differential relaxed compressive/tensile stiffness, said layer being disposed within the matrix material of the surface covering product and below the neutral bending plane of the floor covering.
Another embodiment of the present reinforcing layer enables the floor covering to be elongated in both the machine direction (MD) and across machine direction (AMD). A third embodiment of the present reinforcing layer enables the amount of elongation in the floor covering prior to installation, and therefore, the amount of tension and accommodation after installation, to be increased with some increase in the AMD.
One preferred floor covering has a reinforcing layer with an expandable diagonal pattern glass mat. Due to the controlled pre-stressed tension to which the reinforcing layer is subjected, the adjacent sides of the slits pull apart when the floor covering is subjected to an external tensioning force and the slits interact to form
pivot points, which cooperate such that the reinforcing layer is capable of increasing in dimension and decreasing in dimension, respectively, in a direction generally transverse to an applied tensile or compression force.
In yet another preferred embodiment a plastisol im- 5 pregnated non-woven network or mat has perforations in a parallel sinusoidal pattern, preferably, the pattern is oriented approximately 45° from MD. When tension is applied to the mat in the MD, it expands transversely. As the mat expands laterally from the unstressed condi- 10 tion, the perforations widen.
In still another preferred embodiment, the reinforcing layer is uniformly modified in situ by the chemical modification of the reinforcing layer binder. The pre-modified reinforcing layer is strong enough to perform as a 15 carrier during manufacture yet the floor covering including the modified reinforcing layer is capable of shrinking sufficiently to accommodate the seasonal subfloor dimensional change of a wooden subfloor.
Preferably, the composition and thickness of the plastisol layers are chosen so that the reinforcing layer is disposed within the plastisol or matrix material below the neutral bending plane of the floor covering. The positioning of the reinforcing layer below the neutral 2J bending plane promotes roll-up growth of the floor covering during storage on a wind-up core. Since the reinforcing layer is below the neutral bending plane, the floor coverings are unbalanced and therefore, are not suitable for loose-lay applications. 30
Inclusion of the reinforcing layer eliminates the need for a strippable carrier and the need for a special paper carrier stripping method and apparatus of the prior art. By placing the reinforcing layer below the neutral bending plane and modifying it as described, the layer 35 will resist compression when the floor covering is rolled. However, upon unwinding, and placing flat the reinforcing layer will readily extend due to the elongated upper or outer layer of the floor covering. During roll storage, the reinforcing layer will act to keep the 40 outer elongated surface extended unlike prior art structures where the backing could compress and anneal the structure during long term roll storage. It should be apparent that placement of the reinforcing layer above the neutral bending plane will undesirably inhibit elon- 45 gation of the outer layer in the roll form and cause the matrix material below the reinforcing layer to compress
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view of a reinforcing layer perforated with a diagonal pattern.
FIG. 2 is a plan view of the reinforcing layer of FIG. 1 expanded in two directions when stretched in one direction. 55
FIG. 3 is a plan view of a second embodiment of a reinforcing layer perforated with a sinusoidal pattern.
FIG. 4 is a plan view of the reinforcing layer of FIG. 3 expanded in two directions when stretched in one direction. 60
FIG. 5 is a plan view of a third embodiment similar to the FIG. 3 embodiment but with machine direction perforations.
FIG. 6 is a plan view of the reinforcing layer of FIG. 5 being stretched in the machine direction and showing 65 some expansion in the across machine direction.
FIG. 7 is a cross-sectional view of the floor covering of the present invention.
FIG. 8 is a cross-sectional view of the floor covering of FIG. 7 wound on a wind-up core.
FIG. 9 is a cross-sectional view of the floor covering of FIG. 8 after being unrolled from the core and showing the elongation of the floor covering.
FIG. 10 is a cross-sectional view of another surface covering of the present invention.
FIG. 11 is a schematic representation of the equipment for performing the manufacturing process of the present invention.
FIG. 12 is a plan view of apparatus used to test the flooring structure of the present invention.
An improved process for preparing tension floor coverings is provided which includes disposing a reinforcing layer in a matrix material below the neutral bending plane modifying the reinforcing layer, and placing the reinforcing layer under a controlled prestressed condition whereby the surface covering product elongates and tends to return to its preelongated dimension.
DETAILED DESCRIPTION OF THE
An important concept for understanding one aspect of the invention is the transformation of a reinforcing layer such as a glass mat carrier for a fusable vinyl composition into an internal elastic reinforcement. As part of the manufacturing process, the glass mat or equivalent thereof may be impregnated with foamed plastisol, diagonally slit and cooled while under tension to convert it into "elastic glass". This "elastic glass" functions as if it were a network of miniature bedsprings which can absorb stretching and compressions applied to the surface covering.
Other terminology pertinent to the present invention is defined below to provide clarity in the description.
As used herein "floor covering" is a relatively thin element designed to be installed over a flooring substructure or subfloor.
As used herein, "reinforcing layer" is preferably a layer of non-woven fiber such as polyglass, polyester, or polyamide. However, the term is broad enough to include backing materials in general and specifically, backing felt.
As used in the specification and claims, the term "modified reinforcing layer" means a layer of a resilient floor covering comprising a nonvinyl composition component, the tensile strength and/or elongation of which is changed during or after manufacture of the floor covering in which the,reinforcing layer is disposed. The reinforcing layer may include a vinyl resin composition including plasticizers, stabilizers and fillers but the reinforcing layer is not 100% vinyl resin composition. The cut fiber of a vinyl resin/fiber composition is considered a nonvinyl component.
As used in the specification and claims, the term "elongation due to a controlled pre-stressed condition" includes roll-up growth or elongation during the time when the floor covering is in a rolled condition, on unrolling of the floor covering and before installation. The term also includes growth or elongation which results from the application of a tensile stretching force prior to unrolling of the floor covering before installation.
As used herein, "accommodation" is a built-in property for a floor covering to alter its size and shape to match an unstable subfloor or resist surface stress.