Preparation,Application And Stabilizing Mechanism Of Efficient Organics As Novel Thermal Stabilizers Por Poly (Vinyl Chloride)

Polyvinyl chloride?PVC?is a kind of widely used engineering plastics,however,because of its poor thermal stability,it is necessary to add the thermal stabilizer in the processing formula of PVC.At present,the thermal stability commonly used include lead salts,organic tin,metal soap,etc.,which contain metal ions.With the increasing awareness of environmental protection,the stabilizers containing heavy metal are gradually being eliminated,so the development of environmentally friendly thermal stabilizer to replace the traditional non-environmental protection thermal stabilizer has become a hot spot in the field of thermal stabilizer.The new types of zinc salt stabilizer and organic stabilizer have attracted more and more attention because of their environmentally friendly properties.In this paper,in order to develop the environmentally friendly compound PVC thermal stabilizer,which focus on eliminating the ?zinc burning? in zinc salt stabilizer and enhancing the stability and transparency of nitrogen compound stabilizer,the following works have been done:1?A new type of zinc salt thermal stabilizer was prepared by changing the anion group,and its stability was enhanced by compounding method and the stability mechanism of it was characterized.Dehydroacetic acid zinc?ZnL₂?was synthesized from zinc acetate and dehydroacetic acid by one step method and its structure was characterized.The stability distinction of ZnL₂ and Zinc stearate?ZnSt2?and the stable effect of two systems after combining with Calcium stearate?CaSt2?were investigated by Congo red test,solution acidity test and thermal aging test.The result indicated that the absorption capacity of ZnL₂ on HCl was greatly enhanced due to the introduction of dehydroacetic acid radical,and after mixed with CaSt2,the ?zinc burning? of ZnL₂ was relieved.2?On the basis of researching the ability of nitrogen containing organic stabilizer to delay the ?zinc burning?,nitrogen containing stabilizer was introduced into the soft transparent PVC by introducing long chain groups in the molecule.Amitrole,an organic compound with high nitrogen content,was used as thermal stabilizer for PVC,its stability and the effect of delaying the ?zinc burning? after combining with ZnSt2 were researched.Amitrole performed very well in inhibition initial coloration of PVC and long-term stability by discoloration test.Furthermore,when the ratio of Amitrole and ZnSt2 is 0.4:1.6,the PVC product not only had good long-term stability without ?zinc burning?,but also owned great initial whiteness.In flexible PVC,although N1,N8-di?1H-1,2,4-triazol-3-yl?octanediamide?TOD?improved the transparency of PVC,due to the decrease and change of the stable group,the thermal stability of TOD decreased compared with amitrole.3?The defects were solved targetedly by compounding,so that the nitrogen containing compounds?represented by bis-uracil derivatives?were prepared which had the characteristics of good transparency,high efficiency and good processing performance.Auxiliary stabilizer,epoxy soybean oil?ESBO?and phosphite ester,was added in the stable system of bis-uracil compounds,which improved the initial whiteness and long-term stability of PVC products.The result indicated that when 3 phr ESBO and 6 phr phosphite ester were added into the stable system of 6,6?-Diamino-1,1?,3,3?-tetramethyl-5,5?-?octylidene?bis[pyrimidine-2,4?1H,3H?-dione]?OSU?,the transparency,stability and processability of PVC products were the best.In addition,6,6?-Diamino-1,1?,3,3?-tetramethyl-5,5?-?undecyl?bis[pyrimidine-2,4?1H,3H?-dione]?USU?could also be further improved the transparency of PVC by increasing the carbon chain in the molecule of bis-uracil compounds.Despite the decline in thermal stability of USU stable system,the drawback was solved well by adding 3 phr ESBO.