| 摘要 |
<p>1441329 Gypsum plaster composition DOW CHEMICAL CO 20 Sept 1973 [21 Sept 1972] 44146/73 Heading C1H A gypsum plaster composition suitable for mixing with water to produce a paste or dispersion for plastering comprises gypsum and as additive nitrilotriacetic acid, an alkali metal salt thereof or a mixture thereof and an alkaline agent to control the pH of an aqueous paste or dispersion of the composition in a range of from 6À5 to 14 and to increase the finishing time of the composition. A water retention agent, e.g. non-ionic alkyl cellulose ethers and hydroxyalkyl cellulose ethers may be included in the composition. Examples 2-6 illustrate compositions containing gypsum, lime, nitrilotriacetic acid and methylcellulose. Examples 7-12 illustrate compositions containing gypsum, nitrilotriacetic acid and NaOH, NH 4 OH or lime.</p> |
