需要干燥的德国巴斯夫PA66树脂湿切片被连续地送到干燥塔内, 在干燥塔底部, 湿切片与逆流的温度为125～185 ℃的氮气相互接触而被进一步脱去其表面水分, 生成需要的PA66树脂干切片。华韵塑料公司出售PA66树脂表面发黄原因通过降低PA66树脂在包装时的温度及包装袋内的氧含量, 在包装时和包装储存72 h 后分别取样对德国巴斯夫PA66 树脂的黄点进行分析, 判断PA66树脂在包装后储存时表面发黄产生的原因。通过试验分析发现, 包装时PA66树脂表面温度和氧含量越高, 在储存72 h 后取样分析其黄点越高。包装时PA66树脂表面温度降至60 ℃以下或包装袋内的氧含量降至100×10-6 以下时, 在储存72 h 以后取样分析其黄点变化不大或无变化。The wet slices of German BASF PA66 resin that need to be dried are continuously sent to the drying tower. At the bottom of the drying tower, the wet slices come into contact with nitrogen gas at a countercurrent temperature of 125-185 ℃ to further remove its surface moisture and generate the required PA66 resin dry slices. The reason for the surface yellowing of PA66 resin sold by Huayun Plastic Company was determined by reducing the temperature of PA66 resin during packaging and the oxygen content in the packaging bag. Samples were taken during packaging and stored for 72 hours to analyze the yellow spots of BASF PA66 resin in Germany. The reason for the surface yellowing of PA66 resin during storage after packaging was determined. Through experimental analysis, it was found that the higher the surface temperature and oxygen content of PA66 resin during packaging, the higher the yellow dot of the sample after 72 hours of storage. When packaging, the surface temperature of PA66 resin drops below 60 ℃ or the oxygen content in the packaging bag drops to 100 × When the temperature is below 10-6, after 72 hours of storage, the yellow dot changes little or no changes.