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:
Dec. 07, 1993
Filed:
Feb. 01, 1991
Applicant:
Inventors:
Hou-min Chang, Raleigh, NC (US);
Hasan Jameel, Raleigh, NC (US);
Geoffrey E Seger, Raleigh, NC (US);
Assignee:
North Carolina State University, Raleigh, NC (US);
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
D21C / ;
U.S. Cl.
CPC ...
162 89 ; 162 65 ;
Abstract
A high-efficiency wood pulp bleaching process to produce wood pulps with higher brightness at equal chlorine dioxide usage or of equal brightness at significantly reduced chlorine dioxide usage. The process comprises reacting the chlorine dioxide with wood pulp at a pH of about 5-10 for about 5-40 minutes and then acidifying the mixture to a pH of about 1.9-4.2. The mixture is then allowed to react for about 2 or more hours to complete the two-step high/low pH bleaching process.