磷石膏晶须的改性及其在造纸中的应用

The Modification of Phosphor-Gypsum Whisker and Its Application in Papermaking

关键词:  磷石膏晶须  溶解度  改性  物理性能  留着率

Key Words:phosphor-gypsum whisker  solubility  modification  physical properties  retention rate

摘要:结合磷石膏晶须的结构性能和特点，对磷石膏晶须的改性及其在造纸中的应用进行初步研究。分析了磷石膏晶须经改性剂氯化镁和磷酸改性后其溶解度、留着率的变化及其对纸张物理性能的影响。研究结果表明，将磷石膏晶须用氯化镁和磷酸改性处理后，晶须的表面有一层包覆层，包覆层有效地降低了磷石膏晶须的溶解度。最佳改性条件为：氯化镁用量（相对于磷石膏晶须的绝干质量）为30%，氯化镁与磷酸的摩尔比为1∶1、改性时间20 min、改性温度60℃、磷酸溶液pH值9.0。改性后磷石膏晶须的溶解度可由0.25 g/100 g水降至0.03 g/100 g水。将改性磷石膏晶须用于纸张加填，可在一定程度上提高纸张的白度、不透明度，并改善磷石膏晶须的留着率，但纸张的强度性能有所降低。采用最佳改性条件下改性的磷石膏晶须加填，纸张的白度可提高4.2%，不透明度可提高4.5%，撕裂指数降低2.4%，抗张指数降低38.0%，耐破指数降低27.0%，改性磷石膏晶须的留着率可由原晶须的24.5%提升至77.8%。

Abstract:The dissolution-inhibiting modification of phosphor-gypsum whiskers and its application in papermaking were studied based on the structural properties and characteristics of the whiskers. Magnesium chloride and phosphors acid were used as the modifiers. The change of the solubility before and after modification， retention of whiskers and influence of whiskers on the physical properties of paper were studied. The Experimental results showed that the solubility of modified whiskers reduced because the surface of whiskers forned a coverage layer. The optimum conditions for the modification were as follows: the dosage of magnesium chloride was 30%， the ratio of magnesium chloride and phosphoric acid was 1∶1（mol/mol）， the modification time was 20 min， the modification temperature was 60℃ and the pH value of phosphate solution was 9.0. The solubility of the modified whiskers reduced from 0.25 g per 100 g water to 0.03 g per 100 g water. The handsheets using the modified phosphorus gypsum whiskers as fillers obtained higher whiteness and opacity， lower physical strength and higher retention of whisker. The whiteness and opacity of the handsheets were increased 4.2% and 4.5%， respectively， the tear index， tensile index and burst index reduced 2.4%， 38.0% and 27.0%， respectively， and the retention offiller( whisker） increased from 24.5% to 77.8% under the optimum conditions．