Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Reexamination Certificate
1994-03-22
2001-05-29
Dixon, Merrick (Department: 1774)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
C428S364000
Reexamination Certificate
active
06238789
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to breathable wallcoverings which permit moisture vapor to freely pass therethrough to aid in the control or prevention of mold or mildew growth between the wallcovering and a supporting substrate. More particularly, the invention pertains to decorative, breathable wallcoverings which have a smooth aesthetic appearance.
BACKGROUND OF THE INVENTION
Conventional vinyl wallcoverings are often relatively impervious to moisture and can actually serve as an effective moisture barrier. While moisture impermeability can be desirable in many wallcovering applications, such as in bathrooms and kitchens, moisture impermeable wallcoverings can cause problems in extremely humid climates. Under conditions of high humidity, moist air can permeate the building walls from the exterior inwardly and condense between the wall and the wallcovering on account of the difference between the inside and outside temperature. The low moisture permeability of conventional vinyl wallcoverings prevents moisture and condensate from passing through into the room at a rate equal to the rate at which moisture permeates inwardly through the building walls, thereby causing accumulation of moisture at the side of the wallcovering facing the wall. The trapped water between the wallcovering and the wall provides an excellent medium for growth of molds and mildew on account of the presence of the wallcovering paste which generally contains organic materials which serve as nutrients for sustaining the growth of molds and mildew. Because of the ubiquitous nature of mold and mildew spores, it is almost inevitable that any accumulation of moisture at the interface between a wall and wallcovering will lead to the growth of molds or mildew. Such growth is generally accompanied by staining or discoloration of the wallcovering and by the presence of offensive odors. Conventional vinyl wallcoverings generally have a moisture permeability of about 1 or 2 Perms.
U.S. Pat. No. 5,262,444 to Rusincovitch et al. discloses a breathable, plastic film, useful as a wallcovering material, which is prepared by combining a plastisol with a low boiling point additive, extruding the plastisol mixture containing the low boiling point additive to form a film, and curing the film under conditions whereby the additive volatilizes through the cured film to form a multiplicity of holes in the film. The reference reports Perm values generally ranging from about 1.0 to about 20.0. While the Rusincovitch et al. patent generally reports Perm values which are considerably higher than those of conventional vinyl wallcoverings, still higher moisture permeabilities would be advantageous and desirable.
Pending U.S. patent application Ser. No. 08/013,911, filed Feb. 5, 1993, discloses a moisture-permeable acoustic lamina, suitable for use as a wallcovering, which comprises a woven fabric adhered to a fabric backing by a discontinuous thermoplastic polymer layer. The acoustic lamina is reported to achieve very high Perm values, such as about 72 Perms. The disclosed wallcoverings are particularly well suited for those situations where sound damping and moisture permeability are both important, but where a smooth aesthetic appearance is not desired or can be sacrificed in favor of the excellent moisture permeability and sound damping properties. Specifically, the outer layer of the acoustic lamina is a relatively coarse woven fabric which provides a rough textured surface needed for good sound damping properties. Because of the rough textured surface it is not possible, or at least impracticable, to provide the acoustic lamina of the referenced application with a distinct, sharply-defined printed design or pattern because the printing would tend to deposit more ink on the higher areas and completely miss the recessed areas of the exposed surface.
Accordingly, there exist a need for a breathable wallcovering having a relatively higher permeability, yet which has a smooth outer exposed surface which can be printed with a design or pattern having sharply defined edges.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided a breathable or moisture permeable wallcovering having a porous polymeric ply which is fused to and supported by a nonwoven substrate ply. The porous polymeric ply has a smooth, continuous, aesthetically pleasing appearance, while simultaneously achieving a moisture vapor permeability which prevents moisture from being trapped on or within a wall to which the wallcovering is applied. More specifically, the porous polymeric ply has a substantially macroscopic-continuity or pseudocontinuous character wherein a plurality or multiplicity of miniature or microscopic discontinuities or holes are randomly distributed. To the unaided eye the pseudocontinuous character of the polymeric ply appears to be a continuous, smooth film, the outer or exposed surface of which can be decorated such as by printing a decorative design or pattern using a suitable polymer-receptive ink.
The nonwoven substrate ply or backing is comprised of an array of hydroentangled synthetic polymeric fibers and cellulosic fibers which are physically entangled or mechanically interlocked. The hydroentangled nonwoven substrate is a strong, soft fabric wherein the fibers are more tightly or closely arranged together to provide a smoother, more aesthetically pleasing appearance relative to other nonwoven fabrics. The hydroentangled nonwoven ply has a relatively open and porous or reticular structure which allows for the free passage of air and moisture, such that the moisture permeability of the wallcovering of the present invention is generally controlled by the rate at which moisture is able to permeate the porous polymeric ply.
Because of the relative smoothness of the hydroentangled nonwoven substrate ply and the macroscopic-continuity or pseudocontinuous character of the polymeric ply, the outer or exposed surface of the polymeric ply can be provided with a printed decorative design or pattern having relatively smooth, sharply defined edges having an aesthetic appeal which is comparable to conventional smooth wallcoverings having a low moisture permeability.
On account of its relatively high permeability, the wallcovering of the invention aids in controlling or diminishing mildew growth between the wallcovering and the wall to which it is applied, even when significantly reduced amounts of fungicide are utilized in the porous polymeric ply.
Preparation of the breathable wallcoverings of the invention generally involves applying a thin plastisol coating onto a hydroentangled nonwoven substrate ply or backing. An important aspect of the invention is that the plastisol coating should be applied at a thickness which is sufficiently low to permit localized variations in fiber orientation and small variations in the thickness of the nonwoven substrate ply to cause highly localized flow which results in the formation of a multiplicity of miniature or microscopic discontinuities which are substantially invisible to the unaided eye and which are randomly distributed throughout the coating. The coating, however, should also be thick enough to allow the formation of a macroscopically continuous, smooth coating which can be thermally fused to form a porous polymeric ply having a smooth, continuous appearance onto which a sharply defined pattern or design can be printed. The plastisol coating is fused into a porous polymeric ply by heating the coating to a temperature in excess of the melting or fusion temperature of the polymeric resin or resins contained in the plastisol.
The two-ply breathable wallcovering of the invention can generally be printed with any desired design or pattern using conventional printing techniques, and can be embossed to provide an aesthetic texture as desired using conventional embossing or texturing techniques.
The breathable wallcovering of the invention can be applied to a wall or other substrate using conventional wallcovering paste, to provide a smooth, aesthetically pleasing, decorati
Dixon Merrick
Hudak Daniel J.
OMNOVA Solutions Inc.
Rywalski Robert F.
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