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(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(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.

Abstract: In a process for making paper from an aqueous paper pulp, especially a pulp containing bleached/unbleached mechanical pulps or unbleached chemical pulps, a combination of chemicals is added for improving drainage and retention. As drainage-and retention-improving aids are added a cationic polyacrylamide and a sol of colloidal inorganic particles having at least one surface layer of aluminium silicate or aluminum-modified silicic acid.

Abstract: In the production of paper or pulp sheets from a paper stock, a binder is added which comprises cationic and anionic components to improve the paper characteristics and the stock characteristics, such that increased retention and a more readily dewatered stock are obtained.The anionic component consists of colloidal anionic particles having at least one surface layer of aluminum silicate or aluminum-modified silicic acid, such that the surface groups of the particles contain silicium and aluminum atoms in a ratio of from 9.5:0.5 to 7.5:2.5.The cationic component consists of cationic carbohydrate having a degree of substitution of 0.01-1.0.

Abstract: The invention relates to a method for the production of needle-punch carpets with improved properties, in which method use is made, in the chemical bonding of the needle-felt, of alkali-stabilized silicic acid sol in combination with a latex of an organic binder which is conventional in this context. The amount of silicic acid is of the order of magnitude of from 1 to 30 weight % calculated as dry SiO.sub.2 on dry polymer and the particle size may vary between 1 and 100 nm.