Paper manufacturing process, and papers obtainable by means of that process
US5262006A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 12, 1991 |
| Grant date | Nov 16, 1993 |
| Priority date | — |
| Expiry date | Aug 12, 2011 |
Classification
- Technology area (CPC D)Textiles; Paper
- CPC primaryD21H17/675
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
Process in manufacturing paper wherein stock is prepared using cellulose fiber material which contains calcium sulfate (gypsum). said material being disintegrated in an aqueous medium in order to form part of the stock for the paper to be produced. The characterizing feature of the process is that PA1 (a) carbonate ions and/or hydrogen carbonate ions (CO.sub.3.sup.2- or resp. HCO.sub.e.sup.- ) are supplied to the aqueous medium, and PA1 (b) the pH in the aqueous medium is adjusted to an alkaline value so that calcium carbonate precipitates and forms part of the suspension. There are overall major advantages provided by the process in the context of applying gypsum coatings on paper, inasmuch as broke can be reused in the process without any troublesome gypsum precipitation. Moreover a new grade of coated paper is described, the characterizing feature of this paper being that the filler of the base paper consists entirely or partly of precipitated calcium carbonate (PCC) and that the pigment of the coating layer consists entirely or partly of calcium sulfate.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.