Preparation And Application Of Ca/Zn Based Long-acting Thermal Stabilizer For Transparent PVC Sheet

PVC is the world’s second largest general plastic production,its consumption amount accounts for about 30%of the world’s synthetic resin.However,due to the PVC molecular chain containing allyl chloride,double bond and other unstable structures,its thermal stability is poor,when the temperature is higher than 100℃,it will be dechlorination decomposition,the color of PVC production will gradually turn yellow and black,the mechanical properties also rapidly decline.Therefore,thermal stabilizer is an indispensable additive in PVC processing.At present,the thermal stabilizers which widely used in industry are lead salts,metallic soaps and organotin,epoxy compounds,phosphite esters,polyols and diketones However,the efficiency of the existing thermal stabilizers is still not enough,resulting in a short service life of PVC products.Therefore,it is of great application value to develop a new and efficient thermal stabilizer.(1)firstly,by condensation of lauryl alcohol and citric acid,and by controlling the proportion of both,lauryl citrate ester with flexible chain segment and carboxyl group was synthesized.Ca/Zn-based thermal stabilizer was prepared.The molecular structure and composition of Ca/Zn-based thermal stabilizer were determined by mass spectrometry and ICP-mass(2)It was found that Compared with the traditional stearic acid thermal stabilizer,the new calcium based thermal stabilizer can significantly improve the thermal stability of PVC sheet.After Congo red test,the initial stability time was increased by 17.8min,and after long-term thermal resistance test,the long-term thermal resistance time was increased by more than 40min.Synchronized thermal analysis and RPA test showed that the molecular compatibility of the new Ca-based thermal stabilizer with PVC was stronger than that of stearic acid stabilizers.(3)New Ca/Zn based thermal stabilizer blends with use,the effect of thermal stability isn’t better than using traditional stearic acid stabilizers,the long-term stable time is almost the same,but the new Ca/Zn based thermal stabilizer,mix with epoxy soybean oil will have good synergy,further improve the thermal stability of PVC sheet,and mechanical properties are not affected.(4)Design the synthesis process flow of the new Ca/Zn based thermal stabilizer and PVC processing process flow,complete the design of thermal stabilizer production line with an annual output of 3000 tons of alkylated calcium citrate and zinc,and the design of processing line with an annual output of 5000 tons of PVC sheet material,and analyze the pollution in the process of PVC processing.The treatment method of "three wastes" and safety production standard are put forward preliminarily.(5)Compared with the traditional thermal stabilizer,the new type of thermal stabilizer has advantages in performance,environmental protection and cost performance,and has a development prospect.