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. 11, 1999
Filed:
Dec. 13, 1996
Applicant:
Inventor:
Randall B Nelson, Seattle, WA (US);
Assignee:
Ciba Specialty Chemicals Corporation, Tarrytown, NY (US);
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
D21H / ;
U.S. Cl.
CPC ...
162158 ; 162160 ; 162183 ; 8648 ; 8919 ;
Abstract
A process to increase the whiteness of paper made from a lignin-containing pulp is disclosed which comprises adding to an aqueous slurry comprising a lignin-containing pulp, in the paper making step, an effective amount of a chelating agent to decrease the content of salts of iron and other heavy metals to 100 ppm or less by weight, based on the dry weight of the pulp, or adding to said aqueous slurry an effective amount of a fluorescent whitening agent, or both a) and b).