Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2002-11-04
2004-01-20
Cameron, Erma (Department: 1762)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S306000, C524S315000, C524S591000, C528S049000, C528S084000
Reexamination Certificate
active
06680352
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a process for producing a textile material that, when transfer or film coated, is preferable for use as an artificial leather substrate. The inventive procedure involves (a) producing an elastomer composition of at least four ingredients (a waterborne anionically-stabilized polymer dispersion, an acid-generating chemical, a cloud-point surfactant, and a foam-stabilizing surfactant); (b) incorporating sufficient gas into the liquid mixture to generate a foam; (c) applying the foamed elastomer composition onto a porous textile substrate; (d) heating the treated textile until the elastomer coagulates over the textile substrate; and (e) drying the resultant composite without destroying the coagulated structure. The resultant composite, herein disclosed, exhibits a suppleness that is similar to that of leather and a surface that is suitable for transfer or film-coating to produce artificial leather. The four-ingredient pre-mixture is a long-lasting, shelf-stable composition which will not react until it is exposed to sufficient amounts of heat, thus providing an improvement over the prior art. The particular compositions produced are also contemplated within this invention.
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 textile fabric;
(b) producing a liquid 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) applying the foamed elastomer composition of (b) to the textile fabric of (a);
(d) 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
(e) 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.
Also, the invention concerns the elastomer composition of step (b) of the inventive method itself.
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 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. A further object of the invention is to provide a relatively inexpensive method of making such a composite, by providing an elastomer latex with a shelf-life of at least two weeks and by providing an application method that allows greater manufacturing control. 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.
Nowhere within the prior art has such a specific heat-activated coagulating method utilizing a foamed elastomer composition comprising a waterborne, anionically-stabilized latex, an acid-generating compound, a cloud-point surfactant, and a foam-stabilizing surfactant been disclosed, practiced, or fairly suggested. Such an elastomer composition provides a significant advantage over the two-component (latex and acid-generator) and different three component (latex, cloud-point surfactant, and blowing agent) compositions of the prior art. For instance, the inventive composition has a shelf-life measured in weeks (at least two weeks of stability and non-coagulation after initial admixing) instead of hours at a temperature as high as about 38° C. (100° F.). The coagulation occurs only after exposure to a heat source of sufficient temperature to effectuate such reactivity (such as temperatures greater than about 80° C. or 176° F.).
Additio
Eleazer Howell B.
Vogt Kirkland W.
Cameron Erma
Milliken & Company
Moyer Terry T.
Wilson Charlotte C.
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