Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Reexamination Certificate
1999-01-04
2002-08-27
Kelly, Cynthia H. (Department: 1774)
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
C428S294700, C428S296400, C427S209000, C427S407300, C427S412000
Reexamination Certificate
active
06440543
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a flexible floorcovering tile. More precisely, the present invention relates to a floorcovering tile having a carrier and layers and/or service layers arranged upon this, in particular a linoleum-based floorcovering
BACKGROUND OF THE INVENTION
Flexible floorcovering tiles are known. They may have a service or wear layer based on a synthetic polymer and the service layer may be applied on a carrier, e.g. a carrier made from a natural or synthetic fabric. Glass-fiber fabrics are likewise suitable as carriers. Textile tiles of needlefelt made from e.g. polypropylene, polyamide, polyester, polyacrylonitrile and mixtures of these are known, for example. Tufted textile tiles made from natural and/or synthetic fibers with a carrier (which may be woven and/or nonwoven) made from natural and/or synthetic fibers, where the reverse side of the tile is coated with, for example, latex, polyvinyl chloride or bitumen are also known. There are also tiles with a service layer made from natural cork on a stabilizing carrier made from a woven or nonwoven, combined with a pressure-sensitive adhesive if desired.
Flexible floorcovering tiles are usually produced by stamping out the tile in the desired size from a continuous web of the floorcovering material. The tiles are mostly square with an edge length of from about 30 to about 60 cm, but may also have other shapes and/or sizes.
Tiles having a carrier have the problem that the carrier and the service layer have different coefficients of expansion. This gives a type of “bimetal effect”, i.e. change of temperature, change of humidity or other environmental influences cause the edges of the tile to curve upward (“bow”) or downward. In both cases, even if the tile is adhesively bonded to the floor, the distortion causes it to lift, at least partially, from the floor. The extent to which the tile bends depends on the material of the service layer and of the carrier. When linoleum is the service layer, the distortion of the tile is particularly pronounced, since linoleum shrinks markedly following. production of the floorcovering, on cooling after the curing process in the curing room or curing hall. Since the carrier fabric does not contract, or at least not to the same extent as the service layer, this shrinkage leads to the “bowing” of the tile. In linoleum floorcovering tiles, for example, this effect can be strengthened or weakened by swelling or con-traction, caused by humidity variations in the surroundings, of the organic filler based on ground wood and/or cork which is usually present in the linoleum. Generally, however, the distorting forces do not cancel each other out, so that the tile distorts. This distortion caused by the environment is one of the most important reasons for the inability of floorcovering tiles having a service layer on a carrier, and in particular linoleum floorcovering tiles, to become established in the market.
SUMMARY OF THE INVENTION
An object of the present invention is therefore to provide a floorcovering tile in which the service layer is applied to a carrier and/or a carrier fabric and whose flat shape does not change, or at least changes significantly less than that of conventional floorcovering tiles of this type, under the influence of variations in temperature and/or atmospheric humidity and of changes in other factors in the internal environment.
This object is achieved with the articles characterized in the patent claims. The object is achieved here by the discovery that the distortion of the floorcovering tile caused by the environment can be prevented or considerably reduced by opposing the distorting force exerted by the service layer on the upper side of the carrier with a corresponding force on the underside of the carrier. According to the invention, a floorcovering tile construction is therefore proposed in which a carrier does not only have a service layer on one side, as in conventional tiles, but in which the other side of the carrier and/or carrier fabric is also coated. In the novel floorcovering tile, therefore, the carrier is not situated on one side of the service layer (sometimes called asymmetric tile construction) but is arranged between two layers, at least one of which is a service layer (sometimes called symmetrical tile construction).
The invention and its further advantages are explained in more detail in the following description, with reference to the working examples described under the headings of Examples and Comparative Examples.
DETAILED DESCRIPTION OF THE INVENTION
The novel flexible floorcovering tile has a carrier which is coated on both of its sides. At least one of the two coated layers is a service layer of the floorcovering. The other coated layer may consist of a material which is different from that of the service layer and essentially serves only to counteract the distortion force exerted by the service layer; this layer adheres, on the one hand, to a sufficient extent to the carrier and/or carrier fabric and, if desired, to the material which comes from the service layer on the other side and has penetrated into the carrier fabric, and, on the other hand, it should be capable of being adhesively bonded to the floor. Both layers of the novel floorcovering tile are preferably service layers, the binders and other components of which may be different. For reasons which are explained below, both service layers contain essentially the same coating material, e.g. linoleum, the components, such as binders, fillers, pigments, processing aids and the like being different or essentially the same and being present in the same or different amounts.
The layer thicknesses of the two layers applied to the carrier can be the same or different. In the case of layers which have formulations differing in their components, the distortion of the tile can be counteracted by varying the materials used and their quantity, and by appropriate choice of the layer thickness of the relevant layer. For example, differing expansion of the two layers because of different coefficients of expansion or reaction to humidity change can be compensated by different layer thicknesses. The type and amount of fillers, such as wood flour or ground cork, which swell or shrink when the relative humidity changes, may likewise be changed in the appropriate manner.
Each of the two layers preferably consists of essentially the same type of components in as far as possible the same amounts. In this case, both of the layers and/or service layers applied to the carrier can be produced with essentially the same layer thickness, giving the best balance of the opposing distorting forces.
The novel floorcovering tile has a total thickness of from about 2 to about 6 mm, preferably from about 2 to about 4 mm.
The carrier may be any material which has hitherto been used in floorcoverings or in floorcovering tiles and which is based on natural and/or synthetic woven or knitted fabrics or on textile materials. Examples are jute fabrics, fabrics made from a mixture of natural fibers, such as cotton and staple viscose, glass-fiber fabrics, glass-fiber fabrics coated with coupling agent, fabrics made from a mixture of synthetic fibers and fabrics made from core/sheath fibers with, for example, a core of polyester and a sheath of polyamide. As coupling agent for glass-fiber fabrics, a coating of a styrene-butadiene latex on the glass fibers may be used.
To produce the layers and/or service layers which are arranged on the carrier, any binder used in conventional floorcovering tiles may be employed.
The layers of the novel floorcovering tiles may moreover contain conventional fillers, colorants, such as organic and inorganic dyes and pigments, processing aids, antioxidants, stabilizers and other conventional additives, the choice of which depends on the binder.
For example, floorcoverings based on linoleum comprise a Bedford cement (abbreviated to B cement) made from a partially oxidized linseed oil, at least one resin as tackifier and at least one filler, such as softwood f
DLW Aktiengesellschaft
Kelly Cynthia H.
Shewareged B.
Womble Carlyle Sandridge & Rice, PLLC.
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