Strength loss resistant methods for improving the softening...

Chemistry: molecular biology and microbiology – Process of utilizing an enzyme or micro-organism to destroy... – Textile treating

Reexamination Certificate

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Details

C435S209000, C026S001000, C028S100000, C008S116100

Reexamination Certificate

active

06265207

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to strength loss resistant methods for treating cotton toweling and related fabrics with cellulase so as to impart permanent softening to these fabrics. In particular, the methods of the present invention involve the application of a specified amount of cellulase onto the surface fibers of cotton toweling and related fabrics so as to result in permanent softening of such fabrics. On the other hand, since a specified amount of cellulase is applied only onto the surface fibers of such fabrics, the base fibers (i.e., the interior fibers) of the fabric are not exposed to significant quantities of cellulase. In turn, the interior fibers are not significantly degraded by cellulase and accordingly, strength loss in the treated fabric is reduced as compared to the strength loss arising from treating all of the fibers of the fabric with cellulase.
The methods of the present invention are particularly suitable for use in both a continuous and batch process for treating cotton toweling and related fabrics with cellulase.
2. State of the Art
The use of cellulase to impart permanent softening properties to cotton toweling and related materials is well known in the art. For example, cotton toweling can be treated in a batch or continuous process whereby the treated fabric is washed (immersed) in a cellulase solution at specified conditions. Under such conditions, both the interior and the surface cotton fibers of the fabric are exposed to the cellulase solution. After treatment, the fabric is generally rinsed and dried. Under these conditions, such treatment with cellulase results in permanent softening for the fabric.
However, there is a problem with the treatment of cotton toweling and related fabrics in the manner of the prior art. Specifically, when treated in heretofore known methods for imparting permanent softening, such fabrics experience undesirable weight loss, reduced tensile strength and reduced absorbency. These detrimental attributes can be so severe as to render the treated fabric a poorer quality product as compared to the fabric prior to treatment.
In view of the above, methods for treating cotton toweling and related fabrics which impart permanent softening properties to such fabrics but which also result in reductions in the undesirable properties imparted by prior art processes would be particularly advantageous.
SUMMARY OF THE INVENTION
The present invention is directed to new methods for treating cotton toweling and related fabrics with cellulase so as to impart permanent softening to such fabrics. Unlike prior art processes for imparting permanent softening to such fabrics by exposing the entire fabric to the cellulase solution, the present invention is directed to the discovery that substantial and unexpected improvements are achieved when a specified amount of cellulase is applied onto the surface(s) of cotton toweling and related fabrics (“cotton toweling” as defined herein below). Specifically, the methods of the present invention impart permanent softening to the so treated cotton toweling while also providing for substantial reductions in strength loss, weight loss and loss of absorbency as compared to strength loss, weight loss and loss of absorbency achieved in cotton toweling treated with prior art processes.
Accordingly, in one of its method aspects, the present invention is directed to a method for imparting permanent softening to cotton toweling by treatment with cellulase which method comprises:
(a) applying onto the surface or surfaces of said cotton toweling an aqueous cellulase solution comprising at least about 0.2 grams per liter cellulase wherein the weight amount of said aqueous cellulase solution applied onto the surface(s) of said toweling is between about 10 to 50 percent of the weight of said toweling; and
(b) maintaining said toweling under conditions sufficient to impart softening to said toweling.
In a preferred embodiment, the application of the aqueous cellulase solution to the surface or surfaces of the toweling is by way of spraying and even more preferably by a substantially uniform spraying of the aqueous cellulase solution over the surface or surfaces of the toweling.
In another preferred embodiment, the application of the cellulase solution is to both surfaces of the cotton toweling and even more preferably, the application to both surfaces is conducted simultaneously.
After treatment in the process of this invention, the cotton toweling is then treated in a manner to remove and/or inactivate the cellulase enzyme. One method of removing the enzyme is by thoroughly rinsing the so treated toweling with a cellulase free aqueous solution (i.e., an aqueous solution containing no cellulase). In such an embodiment, the toweling is then dried at elevated temperatures to inactivate any enzyme remaining. Alternatively, the toweling is first treated to inactivate the cellulase enzyme by heating to sufficiently high temperatures for a sufficiently long period of time to inactivate the enzyme. In this embodiment, after inactivation, the toweling can subsequently be thoroughly rinsed and dried.
In one of its articles of manufacture aspects, the present invention is directed to cotton toweling which is permanently soft which toweling is prepared by the methods of this invention.


REFERENCES:
patent: 3650673 (1972-03-01), Ehner
patent: 4435307 (1984-03-01), Barbesgaard et al.
patent: 4479881 (1984-10-01), Tai
patent: 4489455 (1984-12-01), Spendel
patent: 4832864 (1989-05-01), Olson
patent: 4912056 (1990-03-01), Olson
patent: 5019292 (1991-05-01), Baeck et al.
patent: 5232851 (1993-08-01), Cox et al.
patent: 1 368 599 (1974-10-01), None
patent: 4-352881 (1992-07-01), None
patent: WO 92/07134 (1992-04-01), None

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