| abstract |
A method of producing gypsum building board, in which there is added to an aqueous gypsum slurry a water swellable clay and a water-soluble basic polymer having preferential affinity for clay, the slurry being allowed to set so as to form a board, the water-soluble basic polymer consisting essentially of carbon, nitrogen and hydrogen and having a mine groups (which may be primary, secondary, tertiary or quaternary) in the polymer backbone and/or in side chains thereof. |