The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 12, 1998
Filed:
May. 24, 1996
Vinzenz Olip, Scha chtestrasse, AT;
Norbert Steiner, Upper Saddle River, NJ (US);
Degussa Aktiengellschaft, Frankfurt am Main, DE;
Abstract
A method for chlorine-free bleaching of denim textile material composed of warp yarn which is dyed with at least one of (a) indigo dye and at least one sulfur dye, and (b) at least one derivative of indigo dye and at least one sulfur dye, and weft yarn which is undyed and substantially white and which continues to be substantially white after bleaching to provide a denim textile material having a stylish gray cast. The method includes placing denim textile material in water and heating; adding to the water a dispersing agent which is effective to retard deposition of dyestuff stripped from the warp yarn during bleaching onto the weft yarn and which is comprised of polyvinylpyrrolidone; and bleaching the denim textile material by adding to the water an aqueous alkaline bleaching agent which contains a bleaching agent which is selective for the indigo dye or the derivative of indigo dye of the warp yarn and which is selected from the group consisting of formamidine sulfinic acid, and a mixture of formamidine sulfinic acid and at least one reducing carbohydrate, wherein the least one sulfur dye includes a sulfur black dye, and wherein the method provides denim textile material having a stylish gray cast.