GYPSUM PRODUCT AND PROCESS FOR ITS PREPARATION

摘要

The invention relates to a gypsum product which consists of essentially i ntact crystals having a size of between 0.1 and below 2.0 .mu.m. The product is especially suitable as a coating pigment or filler in paper manufacture. The invention also relates to a process for the preparation of a gypsum pro duct, wherein calcium sulphate hemihydrate and/or calcium sulphate anhydrite , water and a crystallization habit modifier are contacted so that the calci um sulphate hemihydrate and/or calcium sulphate anhydrite and the water are reacted with each other and form a crystalline gypsum product. The calcium s ulphate hemihydrate and/or calcium sulphate anhydrite is/are used in such an amount that the reaction mixture formed from the calcium sulphate hemihydra te and/or calcium sulphate anhydrite, the water and the crystallization habi t modifier has a dry matter content of between 50 and 84 % by weight. Then, said gypsum product can be formed which consists of essentially intact cryst als having a size of between 0.1 and below 2.0 .mu.m.