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. 21, 1996
Filed:
Feb. 23, 1995
Hans U Huth, Egelsbach, DE;
Walter Kamutzki, Dieburg, DE;
Hoechst Aktiengesellschaft, , DE;
Abstract
Neutral sizing of base paper pulp in a conventional aqueous suspension at a neutral pH for the production of sized, acid-free base paper by internal sizing with the use of aqueous cationic copolymer dispersions having a minimum cation activity of 20 .mu.mol/g of solids, more than half of the cationic charge being located on the surface of the dispersion copolymer particles, in combination with polymeric retention aids, the weight ratio of the polymeric retention aid to the cationic dispersion copolymer preferably being 0.3:1 to 0.005:1, in a quantity of up to 2% by weight of cationic dispersion copolymer, relative to the dry weight of the raw cellulose fibers. The internal sizing is effected by intensive mixing of the neutral sizing agent components with the raw cellulose fiber suspension, with the proviso that either the polymeric retention aid is added first and the cationic plastics dispersion is metered in afterwards or the two agents are metered separately at the same time into the cellulose fiber suspension, if desired with the additional use of inert fillers, pigments, dyes and conventional auxiliaries, and by subsequent isolation of the acid-free base paper in the conventional manner, if appropriate as base paper webs or base paper boards, and drying of the internally sized neutral base paper. In the combination according to the invention with the polymeric retention aid, the cationic plastics dispersion surprisingly shows a synergistic increase of its internal sizing effect in the neutral pH range.