Chemistry: molecular biology and microbiology – Process of utilizing an enzyme or micro-organism to destroy... – Textile treating
Reexamination Certificate
1994-02-03
2001-10-09
Lankford, Jr., Leon B. (Department: 1651)
Chemistry: molecular biology and microbiology
Process of utilizing an enzyme or micro-organism to destroy...
Textile treating
C435S209000, C008S116100, C026S001000, C028S100000
Reexamination Certificate
active
06300122
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to methods for improving the feel and appearance characteristics of cellulosic-containing fabrics. In particular, the methods of the present invention are directed to applying a cellulase solution under pressure to cellulosic-containing fabric during the manufacturing process under conditions wherein the solution cascades over the fabric. When so conducted, the treated cellulosic-containing fabric has improved feel and appearance characteristics as compared to the fabric prior to treatment, which improvement is achieved in an efficient manner. Additionally, this process removes a portion of the immature cellulosic-containing fibers from the fabric which provides for further improvements in the quality of the so-treated fabric.
2. State of the Art
During or shortly after its manufacture, cellulosic-containing fabrics are generally treated in a manner which improves their appearance and accordingly their quality. One means of improving the appearance and luster of such fabrics is to treat the fabric with a caustic alkaline reagent, for example, sodium hydroxide, and the like. This process of treating fabric with a caustic is termed “mercerization” and provides beneficial results to the so-treated fabric including increased dye yield, and increased tensile strength, increased luster, and appearance. However, use of such caustic reagents raises handling problems and safety concerns.
The art, in general, also teaches the application of cellulase enzymes to cellulosic-containing fabric to enhance the feel and/or appearance of the fabric. Such applications are described, for example, by Cox et al., U.S. Pat. No. 5,232,851, which discloses methods for treating non-dyed and non-finished cotton woven fabrics with a cellulase solution with agitations and under conditions so as to produce a cascading effect of the solution over the fabric. When so treated, improvements in feel and appearance are achieved under more efficient conditions as compared to treatment of the fabric with agitation only. Other fabrics heretofore treated with cellulase solutions under agitation and cascading conditions include cotton knits and cotton denims.
Notwithstanding the advantages and improvements achieved by treating cellulosic-containing fabrics with a cellulase solution with agitation and under conditions so as to produce a cascading effect of the solution over the fabric, the processes described by Cox, et al., U.S. Pat. No. 5,232, 851, and others nevertheless have reaction times which are undesirably long for an efficient manufacturing process. Moreover, while such processes reduce fabric strength loss as compared to processes which do not agitate and cascade the cellulase solution over the cotton-containing fabric, additional reductions in strength loss are desirable.
In any event, the above described methods of contacting cellulosic-containing fabrics during manufacture with a cellulase solution are contrasted with methods of cleaning fabrics with a laundry detergent composition containing cellulase because the cellulosic-containing fabrics employed in the methods described herein are treated during the manufacturing process, e.g., prior to application of a finish to the fabric.
In spite of the above described methods, there is a continuing need for methods to upgrade the quality of cellulosic-containing fabrics by treatment with a cellulase solution while reducing/minimizing the treatment reaction time, particularly during the manufacture of cotton woven fabric. Likewise, there is a need for methods to upgrade the quality of cellulosic-containing fabrics by treatment with a cellulase solution during the manufacturing process that are more efficient than the methods of merely cascading and/or agitation. It would be particularly desirable if such methods also resulted in fabrics having improved appearance and feel with minimal strength loss as compared to fabrics prior to treatment.
SUMMARY OF THE INVENTION
The present invention relates, in part, to the discovery of new methods for more efficiently improving the feel and appearance of cellulosic-containing fabrics during the manufacturing process. Substantial and unexpected improvements in the treatment time and in the reduction of strength loss of cellulosic-containing fabrics have been discovered by contacting the fabric with a cellulase solution under pressure wherein the cellulase solution cascades over the fabric.
When treated in the manner of the present invention, the cellulase exposure time required to achieve improved feel and appearance of the treated cellulosic-containing fabric is significantly reduced as compared to prior art cellulase treatment processes including methods using agitation/cascading but without pressure application as described by Cox, et al., U.S. Pat. No. 5,232,851. Because the fabric is exposed to the cellulase solution for significantly shorter periods than those previously used, strength loss in the fabric as a result of the cellulose treatment is reduced as compared to known cellulase exposure procedures previously used.
Accordingly, in one of its method aspects, the present invention is directed to a method for improving the feel and appearance of cellulosic-containing fabric prior to finishing of the fabric which method comprises contacting the fabric with a cellulase solution under pressure, and under conditions wherein the solution cascades across the fabric, and under conditions effective in improving the feel and appearance of the cellulosic-containing fabric.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
As noted above, the methods of this invention provide for cellulosic-containing fabric having the desired properties of improved feel and appearance with a significant reduction in the amount of treatment time with the cellulase solution. The reduction in treatment time results in reduced strength loss in the fabric and provides for a more efficient process. Prior to our discussing this invention in detail, the following terms will first be defined.
1. Definitions
The term “cellulosic-containing fabric” means fabrics made of pure cotton or cotton blends; when cotton blends are employed, the amount of cotton in the fabric should be at least about 40% by weight cotton; preferably, more than about 60% by weight cotton; and most preferably, more than about 75% by weight cotton. When employed as blends, the companion material employed in the fabric can include one or more non-cotton fibers including synthetic fibers such as polyamide fibers (for example, nylon
6
and nylon
66
), acrylic fibers (for example, polyacrylonitrile fibers), and polyester fibers (for example, polyethylene terephthalate), polyvinyl alcohol fibers (for example, Vinylon), polyvinyl chloride fibers, polyvinylidene chloride fibers, polyurethane fibers, polyurea fibers and aramid fibers. It is contemplated that regenerated cellulose, such as rayon, could be used as a substitute for cotton in the methods of this invention.
The term “finishing” as employed herein means the application of a sufficient amount of finish to the fabric so as to substantially prevent cellulolytic activity of the cellulase on the fabric. Finishes are generally applied at or near the end of the manufacturing process of the fabric for the purpose of enhancing the properties of the fabric, for example, softness, drapability, etc. Finishes useful for finishing a cellulosic-containing fabric are well known in the art and include resinous materials, such as melamine, glyoxalol, or ureaformaldehyde, as well as waxes, silicones, fluorochemicals and quaternaries. When so finished, the cellulosic-containing fabric is also substantially less reactive to cellulase.
The term “cellulase” as employed herein refers to a multi-enzyme system derived from a microorganism which acts on cellulose, especially crystalline forms of cellulose, and its derivatives to hydrolyze cellulose and give as primary products, glucose and cellobiose. Such cellulases are synthesized by a large number of microorganis
Burns Doane , Swecker, Mathis LLP
Genencor International
Lankford , Jr. Leon B.
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