Surface Modification Of Natural Barite Powder And Technological Design

Barite powder is an important chemical raw material. It was widely used as filler in paints, rubber, paper and other industries, and it was also the most important filler used in powder coating in most countries. However, barite powder filler and matrix, that is, the organic polymer surface or interface are different in nature, compatibility is poor. When barite powder used as direct filler, it is difficult to disperse with organic matrix and has poor compatibility with the resin in the powder coating, and which can impact the gloss of powder coatings. Therefore, it should be modified to improve its physical and chemical characteristics of the surface before filled to the powder coating, which can enhance its compatibility with the resin and the dispersion with the organic matrix, and then it could improve the gloss and integrated performance of powder coating.Natural barite powder was modified with the method of surface chemical coating, the proess of dry modified, and the modifier of stearic acid salt series and L-4 coupling agent. In order to study the modified effects of stearic acid salt series, the way of sedimentation volume was used. The results showed that the barite powder modified with sodium stearate had the slowest settling velocity and the best dispersion in benzene. By measureing the surface contact angle of barite powder modified with different amount of L-4, it showed that when the the amount of L-4 was 1.0%, the surface contact angle of water drop on the tablet of barite powder was 137.5°. IR and thermal analysis were used to analysis the modified mechanism of the modified barite powder, which was modied with sodium stearate and modified L-4 coupling respectively. And the results showed that the modified mechanism of sodium stearate was physical adsorption, and which of L-4 coupling agent was chemical bonding. The modified barite powder was used in powder coating as filler, and it made that the coating properties became better, the gloss of coating got improved, and the surface of coating became smooth.The main factors affecting the modification of L-4 coupling to modify barite powder have been studied with orthogonal test, and the results showed that the optimum modified conditions were as follows: amount of L-4 coupling was 1.0%, modification time was 30 min and modification temperature was 80℃. The sizes of the factors affecting the effects of modification were: modified dosage> modified temperature> modification time.Based on research results, desiging a continuous surface modification process of barite powder, which was annual output of 3,600 tons. And the contents of this design included the calclaution of material balance and heat balance, the selection and design of major equipments, and the economic evaluation of the process. The economic evaluation results showed that the design had advantages of low investment and fast cost-recovery, which could bring great economic benefits to the enterprise.