Impurities in CPE usually refer to particles in CPE that are not plasticized or difficult to plasticize, such as hyperchlorinated CPE, yellow discolored particles, mixed with other material impurities, etc., which can usually be found by CPE spot pressure film test. This impurity particles exist in every manufacturer, but how much to say, because the reaction is not entirely possible in the chlorination reaction, the reaction time will be long, and the reaction kettle will not be clean, so this is the manufacturer's production process problem.
The impurity particles in CPE are often difficult to plasticize, and it is easy to show on the surface of its modified PVC products, especially the thin product surface is easy to identify, sometimes you will find small points on the surface of the product, and sometimes you will find concave in the opposite direction, and the color is slightly yellow than the color of the product. General impurities will be concave when exiting the die, and will be flat after cooling. These impurities not only affect the appearance of the product, but also fatal defects in PVC products, when the filling becomes high, it will break from the impurity point, seriously affecting the toughness of the product.
In addition, impurity points on the surface of PVC products also appear as white particles or pits on the surface of products. When the elemental analysis of the white particles was carried out, it was found that it was mainly the composition of the calcium mixed lubricant, which may be caused by the agglomeration of calcium carbonate if the CPE is plasticized quickly when mixing at high temperature.
Although impurity particles are difficult to eliminate, but still need to control, light industry standard QB/T5079-2017, not more than 50 /100g impurity content is still necessary.
