Wuhan Handern PVC Transparent Sheet
DATE：2020/10/13 9:03:51 / READ： / SOURCE：This station
Wuhan Handern PVC Transparent Sheet
1. Material selection and formula design1) Material selection
(1) Resin selection. The rigid PVC transparent board uses PVC resin as the main raw material, and the performance of the resin directly affects the processing performance and product quality. For this reason, SG-7 resin, which won the National Quality Product Award from Tianjin Chemical Plant, was selected. www.handern.com Non-woven equipment
(2) Stable system. As we all know, during the production process of PVC resin, either due to the fluctuation of the polymerization temperature control, or due to the residue of additives in the resin during polymerization, the structure and purity of the resin may be affected. Most of its molecular structure is head and tail segments. After heat gathering, the HCl must be degraded and removed, and the removed HCI will catalyze the further degradation of PVC, so that the incremental dehydrochlorination will proceed very quickly, and a polyene segment will soon be formed. For this reason, it is necessary to add a stabilizer that can inhibit or slow down the decomposition of PVC in the formula, and the stabilizer is the acceptor of HCI to avoid the catalytic degradation of HC. The type of stabilizer has a greater impact on the transparency of the product. On the one hand, the color and compatibility of the stabilizer with PVC, and the difference in refractive index affects the transparency; on the other hand, the color, compatibility, and refractive index of the stabilizer and HC and other reaction products There is also a greater impact on transparency. Based on relevant information and the experience of brother factories, we selected Beijing 8831 organotin stabilizer (i.e. di-n-octyltin) produced by Beijing No. 3 Chemical Plant. The stabilizer has good compatibility with PVC, and its reaction product has good compatibility with PNC, so it has good transparency; it can not only trap PNC degradation product HCl, but the product will not promote the decomposition of PVC. Moreover, it can react with activating groups to form a stable structure, which can inhibit the early decomposition of PVC, so it has good initial coloring properties; at the same time, the organotin stabilizer also has antioxidant properties. It is currently an ideal transparent stabilizer in China. Although it is expensive, it is still selected because of its unique properties. www.handern.com Non-woven equipment
(3) Lubrication system. In the process of extruding hard PVC, the lubricant can prevent the material from sticking and staying in the barrel wall and screw groove, thereby promoting the flow of the material, helping the product demolding, and ensuring the smooth and glossy surface of the product. A proper amount of lubricant can reduce power consumption, increase production rate, and prevent resin degradation caused by friction and improve the efficiency of stabilizers. The amount of lubricant added and the balance of internal and external lubricants are also related to product quality and processing conditions. If the amount of external lubricant added is too small, the friction between the material and the equipment and the mold will be large, and mold sticking will occur easily, and the surface quality of the product will decrease; if the external lubricant is too much, the equipment load will drop sharply, and the forced feeding performance inside the machine will decrease, which affects productivity. At the same time, the plasticization of the materials is not uniform, so that the mechanical properties of the product deteriorate, and the finished product cannot even be produced. In addition, because the external lubricant is generally poorly compatible with PC, excessive precipitation will occur and affect the transparency of the product. The amount of internal lubricant added is too small to improve the friction between the material molecules, resulting in local overheating and decomposition, and at the same time, the production capacity is affected due to the heavy load of the equipment; when the internal lubricant is excessive, it will over-plasticize. As a result, the product becomes brittle, and the heat resistance of the product also decreases with the increase of the internal lubricant. www.handern.com Non-woven equipment
Author：admin