| 摘要 |
PCT No. PCT/SE90/00037 Sec. 371 Date Aug. 12, 1991 Sec. 102(e) Date Aug. 12, 1991 PCT Filed Jan. 16, 1990 PCT Pub. No. WO90/09483 PCT Pub. Date Aug. 23, 1990.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 (a) carbonate ions and/or hydrogen carbonate ions (CO32- or resp. HCOe- ) are supplied to the aqueous medium, and (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. |
