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:
Mar. 06, 2012
Filed:
Mar. 27, 2007
Applicants:
Aki Vilpponen, Varkaus, FI;
Panu Tikka, Espoo, FI;
Inventors:
Aki Vilpponen, Varkaus, FI;
Panu Tikka, Espoo, FI;
Assignee:
Oy Lannen Tutkimus—Western Research Inc., Espoo, FI;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
D21C 9/16 (2006.01);
U.S. Cl.
CPC ...
Abstract
A process for the bleaching of chemical pulp, comprising a first chlorine dioxide treatment (D) of the initial bleaching and chelation (Q) to be carried out in connection therewith, forming together a DQ treatment. The process is characterized in that the chelation is carried out at the pH of from 2 to 7, and it is followed by an alkalizing stage (N) of the pulp, without intermediate washing for raising the pH of the pulp to above 7 and at most to 12 prior to a following stage which is a washing step.