| 摘要 |
1,156,239. Perphthalic acid compositions. PPG INDUSTRIES Inc. 18 Dec., 1967 [19 Dec., 1966], No. 57346/67. Heading C2C. The invention comprises compositions consisting of a perphthalic acid core encased in a protective coating of hydrated magnesium sulphate in which the content of magnesium sulphate heptahydrate is limited to less than 10% by weight of the total hydrated magnesium sulphate. The compositions may be produced by mixing magnesium sulphate and a perphthalic acid in the presence of water and heating the encapsulated product to reduce the magnesium sulphate heptahydrate to less than 10% by weight of the hydrated magnesium sulphate present. |
