Controllable preparation method of ultrathin anhydrous calcium sulfate crystal whisker with high length-diameter ratio

Abstract

The invention relates to a controllable preparation method of ultrathin anhydrous calcium sulfate crystal whisker with high length-diameter ratio. The method comprises the steps of firstly, preparing active calcium sulfate hemihydrate by taking calcium sulphate dihydrate as raw materials; then conducting acid treatment at normal temperature under a particle size control agent condition to prepare ultrathin and ultrahigh calcium sulfate hemihydrate; then adding contained water solution, conducting hydrothermal reaction to obtain an intermediate product, namely calcium sulfate hemihydrate crystal whisker; and finally mixing the intermediate product and an inorganic fluxing agent, roasting at 200-800 DEG C, washing and drying to prepare the ultrathin anhydrous calcium sulfate crystal whisker with the high length-diameter ratio, for which, the diameter is 0.005-10mum, the length is 10-5000mum, the length-diameter ratio is 100-10000, and the main content is more than 95wt%. According to the controllable preparation method, the raw materials are easily available, the process is simple, the additional value is high, the prepared ultrathin anhydrous calcium sulfate crystal whisker has the characteristics of thin and small diameter, high length-diameter ratio, uniform morphology and stable performance, and can be used as reinforcing materials to be used in industries such as plastics, rubber, paper making and ceramics.

Description

technical field [0001] The invention relates to a controllable preparation method of anhydrous calcium sulfate whiskers, belonging to the technical field of preparation of inorganic chemical materials. Background technique [0002] my country has abundant natural gypsum and industrial by-product gypsum resources, which provide good conditions for the development of calcium sulfate whisker materials. Compared with other whisker materials, calcium sulfate whiskers have the characteristics of good mechanical strength, non-toxicity, stability, and low price. Therefore, its controllable preparation has attracted increasing attention in recent years. [0003] The research on calcium sulfate whiskers was first carried out in the United States and Germany. In 1976, U.S. patents (US3961105 and US patent3961105) and German patent (DE2613651) introduced the method of using calcium sulfate dihydrate as raw material for the first time and adopting hydrothermal reaction-roasting method ...

AI Technical Summary

Problems solved by technology

[0004] In terms of aspect ratio control, Li Xiangqing etc. have prepared calcium sulfate whiskers with a length of several hundreds of microns by adding ethanol and cetyltrimethylammonium bromide. Chen Qiang, Zhang Lin'e, Mu Jin, Preparation of micron-sized calcium sulfate whiskers, Applied Chemistry, 2007, 24(8), 945-948); Ye Ying et al (Ye Ying, Chen Xuegang, Lu Shuangshuang, Xia Meisheng, a kind of dolomite The method for preparing calcium sulfate whiskers, CN 101323974A) uses dolomite as raw material to prepare calcium sulfate hemihydrate whiskers with an aspect ratio of 10-1000 by using microwave radiation heating, aging and drying methods, but the product morphology is not sensitive to microwave radiation heating. The method is relatively sensitive, and it is difficult to enlarge the project

[0005] In terms of diameter control, Gareth, Kuang, and Chen et al. used the microemulsion method to prepare diameters of 0.01 to 0.1 in the presence of surfactants such as lauryl polyether, polyethylene glycol octylphenyl ether, and polyether alcohol. μm, calcium sulfate nanowires with a length of 10-100 μm and an aspect ratio of 50-1000 (Gareth D R, Richard E G, Stephen J H, et al.Formation and Morphology of Calcium Sulfate Nanoparticles and Nanowires in Water-in Oil Microemulsions, Langmuir, 1999 , 15(6), 1993-2002; Kuang D B, Xu A W, Fang Y P, et al., Preparation of Inorganic Salts (CaCO 3 , BaCO 3 ,CaSO 4 ) Nanowires in the Triton X-100 / Cyclohexane / Water Reverse Micelles, Journal of Crystal Growth, 2002, 244, 379-383; Chen Y, Wu Q S, Facile Synthesis and Properties Research of Single Crystal Calcium Sulfate Nanotube Through Reverse Micelle Method, Colloid and Surfaces A: Physicochemical and Engineering Aspects, 2008, 325, 33-37), but the microemulsion preparation process is complicated, and most of the organic raw materials used are high in price and large in quantity, so it is still in the laboratory research stage so far, and has not realized industrialization; Li Wu et al. ( Li Wu, Li Shengli, Zhang Zhihong, et al. Preparation process of calcium sulfate whiskers, CN 1317430A) using dihydrate gypsum as raw material, controlling the ratio of gypsum and water to 1:5-20, and reacting at 70-250°C for 0.75-10 hours, Calcium sulfate dihydrate whiskers with a diameter of 0.1-4 μm and a length of 10-200 μm were obtained, but the thermal stability of the calcium sulfate dihydrate whiskers was poor, and the morphology of the whiskers would be destroyed when the temperature exceeded 120°C; Yuan Zhitao et al. (Yuan Zhitao, Wang Xiaoli, Han Yuexin, et al. Preparation of ultrafine calcium sulfate whiskers by hydrothermal method, Journal of Northeastern University (Natural Science Edition), 2008, 29(12), 475-675) using finely ground raw gypsum (18.1μm) as raw material, Calcium sulfate hemihydrate whiskers with an average diameter of 0.19 μm and an aspect ratio of 98 were prepared under hydrothermal conditions with a slurry solid content of 5%, pH=9.8-10.1, and 120°C. The disadvantage is that the grinding cost is relatively high. And the whisker length needs to be increased

[0006] In a word, although the predecessors have carried out some work on the diameter and length control of calcium sulfate whiskers, there are still problems such as harsh process conditions or poor product morphology (thicker diameter, shorter length, uneven shape), etc. Limits further industrial applications of related technologies

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