Fabric (woven – knitted – or nonwoven textile or cloth – etc.) – Coated or impregnated woven – knit – or nonwoven fabric which... – Coating or impregnation improves elasticity – bendability,...
Reexamination Certificate
2000-06-23
2003-07-29
Juska, Cheryl A. (Department: 1771)
Fabric (woven, knitted, or nonwoven textile or cloth, etc.)
Coated or impregnated woven, knit, or nonwoven fabric which...
Coating or impregnation improves elasticity, bendability,...
C521S065000, C521S072000
Reexamination Certificate
active
06599849
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a knitted textile that is foamed with an elastomeric latex composition to create a textile-elastomer composite, the composite being particularly preferable for transfer or film-coating to create an artificial leather substrate. In particular, the knitted textile-elastomer composite exhibits improved compressibility, pliability, and drape, characteristics that are commonly associated with high quality leather.
DISCUSSION OF THE PRIOR ART
Polymer latexes (e.g., polyurethane and acrylate) have been utilized in a variety of ways, most notably as coatings or finishes on fabric surfaces. Such latexes may provide, for example, a barrier to potentially adverse environmental conditions. Furthermore, leather substitutes have also been produced through the use of waterborne polymer latexes. Such substitutes provide an alternative to more expensive, genuine leather articles. Such artificial leather substrates must exhibit the suppleness and appearance that are characteristic of genuine leather, and must withstand heavy and repeated use within automobile and furniture upholstery, for example.
Previous polyurethane-based leather substitute products include composites produced through the reaction of a polyurethane latex and an acid-generating chemical (specifically, hydrofluorosilicic salts). Such a composition is disclosed in U.S. Pat. No. 4,332,710, to McCartney, entirely incorporated herein by reference. McCartney teaches heat-activated coagulation of a polyurethane latex in conjunction with only an acid-generating chemical, such as salts of hydrofluorosilicic acid. Such a composition and method present some difficulties, primarily in the use of an acid-generating chemical alone to provide ionic coagulation. This two-component system often results in a non-uniform distribution in the textile substrate and can form stringy structures, which are unattractive as suede leather substitutes. Of particular concern are the environmental and safety issues associated with the use of hydrofluorosilicic acid salts, which are highly discouraged within the industry but which are patentee's preferred acid-generating chemicals.
Other prior teachings involving polymer latex heat-activated coagulation include U.S. Pat. No. 4,886,702 to Spek et al. The '702 patent discloses a method utilizing a composition comprising a waterborne polymer latex (including polyurethane and acrylate), a cloud-point surfactant coagulant, and a blowing agent, which evolves gas during heating. However, such a composition does not produce preferable leather-like textile products due to the stiff hand that results from the effect of the blowing agent. Second, the preferred blowing agent is freon, which is being phased out of production due to its deleterious environmental impact. Third, the coagulation process requires the addition of acid and/or salt compounds, which have the potential to coagulate the latex mixture prior to contact with a textile substrate, thus resulting in a non-uniform dispersion on the substrate surface. Last, the shelf-life of patentees' composition is, at a maximum, only eight hours in duration, thereby placing certain limitations on manufacturing flexibility.
Furthermore, U.S. Pat. No. 4,171,391, to Parker, teaches polyurethane latex coagulation within an aqueous ionic or acid bath. Because the determining factors are the type and amount of ionic material (or acid) and the rate of diffusion of such a constituent from the bath to the substrate material, such a procedure is difficult to control. As a result, there is a lack of consistent uniform dispersion and coagulation from one textile substrate to another. Particularly with heavier fabric substrates, the necessary contact times may be as long as 30 minutes, translating into high costs for the manufacturer and, ultimately, the consumer.
These shortcomings indicate a need, then, within the industry, for improved leather-like textile-elastomer composites, which are relatively inexpensive to make, which have a more realistic appearance and improved aesthetic qualities when transfer or film-coated, and which have an overall better performance over the prior art.
SUMMARY
This invention concerns a leather-like textile-elastomer composite, and a method of producing this composite, the method comprising the sequential steps of:
(a) providing a knitted textile fabric;
(b) foam-coating the knitted fabric with a liquid elastomer composition, the elastomer composition comprising:
(i) a waterborne, anionically-stabilized polymer latex;
(ii) an acid-generating chemical;
(iii) a cloud-point surfactant; and
(iv) a foam-stabilizing surfactant,
wherein sufficient gas is incorporated into the liquid elastomer composition to produce a foamed elastomer composition;
(c) heating the coated textile to an initial temperature to effectuate a uniform dispersion and cause coagulation of said elastomer composition over the textile fabric; and
(d) subsequently heating the coagulated fabric to a temperature higher than the temperature utilized in step (d) in order to dry, but not destroy, the coagulated elastomer over the fabric.
The addition of step (e), in which the textile-elastomer composite is subsequently transfer or film-coated, results in a high quality artificial leather substrate that exhibits the compressibility, pliability, and drape that are characteristic of genuine leather articles.
It is thus an object of the invention to provide an improved, more aesthetically pleasing leather-like fabric-elastomer composite. The term fabric-elastomer composite refers to an article comprised of a knitted textile fabric, which has been coated on at least one side with an elastomer composition. An object of the invention is to provide a composite that has a more realistic, leather-like appearance and is more aesthetically pleasing when transfer or film-coated. Another object of the invention is to provide a method of producing a leather-like article which includes environmentally safe, nontoxic, low odor, noncombustible chemicals. Yet another object of this invention is to provide leather-like composites, which when transfer or film-coated, are suitable for all intended uses in which a user requires or desires a faux-leather substrate.
Perhaps most importantly, the inventive method and composition impart a soft, fine-structured coagulum leather-like finish to fabrics which is comparable to, if not better than, leather-like finishes produced with organic solvent-borne systems (such as those described in U.S. Pat. No. 4,886,702, noted above). Thus, the inventive method and composition provide the means to produce, in a very safe manner, a fabric-elastomer composite having a desirable suppleness and appearance, which, when transfer or film-coated, effectively simulates a genuine leather article.
The term fabric-elastomer composite refers to an article comprised of two layers, wherein one layer is a knitted textile fabric, and the second layer is an elastomeric coating that has been applied to at least one side of the knitted fabric. The second, elastomeric layer is partially incorporated into the knitted textile, creating a seamless transition between the two layers. As noted above, the inventive foamed elastomer composition comprises five materials: a waterborne polyurethane latex, an acid-generating chemical, a cloud-point surfactant, a foam-stabilizing surfactant, and sufficient gas to produce the foamed product.
An anionically stabilized polymer latex is an emulsion or dispersion formed from a polymer, an anionic surfactant, and water. Polyurethane, acrylic, or polyurethane-acrylic latex is preferable, but any waterborne anionically stabilized polymer latex may be used. The preferred latexes are those having at least a 30% solids content. One preferred example of a polyurethane latex is EX-62-655 (40% solids), available from Stahl. A suitable polyurethane-acrylic latex is Paranol T-6330 (50% solids), available from Parachem. Examples of suitable anionic surfactants for use in the polymer dispersion include, but are not li
Eleazer Howell B.
Vogt Kirkland W.
Befumo Jenna-Leigh
Juska Cheryl A.
Milliken & Company
Moyer Terry T.
Wilson Charlotte C.
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