| 摘要 |
1,226,333. Plaster compositions. BPB INDUSTRIES Ltd. 22 March, 1968 [22 March, 1967], No. 13546/67. Headings C1A and C1H. Cast gypsum sheets, slabs or blocks, e.g. plasterboard with a gypsum core, contain tartaric acid as an additive to reduce " plastic flow". The acid is added in forming the water/ plaster mix, either by adding it as solution or suspension in the water or as a solid mixed with the plaster. The amount of tartaric acid used is preferably in the range 0À005-0À2% by weight, based on the dry plaster used in the mix, and the mix may be formed, cast and set under non-alkaline conditions. Setting accelerators and other conventional additives may also be used in the mix. Foaming agents may be added to the water/plaster mix, e.g. resin soap based on pine resin or " Teepol " (Registered Trade Mark) foaming agents based on sodium secondary alkyl sulphates and sodium benzene sulphonates. |
