The Synthesis Of Ester-tin And The Studies On Their Thermal Stability For Poly(Vinyl Chloride)

Studies on synthesis method and composite of ester-tin are in progress actively, since the first ester-tin compound was produced by Akso company Holland in 1976. In recent years, new (ester-tin) products are manufactured ceaselessly and applied to produce environment friendly and transparent PVC products, and the intensive study was concentrated on developing new synthesis routes and new compounds. Studies on this field started in the early 1990s in china, and the patterned manufactures were in progressed on small scales. However, the products were not industrialized massively because of immature process routes, accidents and unstable quality that precipitation, colouration and strong smell may occur within several days after being synthesized. In this paper, in order to solve this problem a new ester-tin synthesis route was proposed so that novel composite ester-tins with low tin content and low toxicity were prepared.Studies in this paper are comprised of three sections:studies on the synthesis of bis(β-butyloxycarbonylethyl) tin dichlorides intermediate by mixing solvents, which was focused on the effects of synthesis conditions to the components and quality of products; Studies on the synthesis methods of ester-tin thermal stabilizers synthesized by Na2CO3 mixing solvents, in which the static thermal stability, the dynamic stability and rheological behavior were tested; Studies on ester-tin, which composited with methyltin mercaptide, metal soap, antioxidant bisphenol a and HLDs were carried out. Two kinds of composite thermal stabilizers of ester-tin(methyl acralate)/methyltin mercaptide(1:1)and ester-tin(methyl acralate)/ antioxidant bisphenol a/HLDs (2:0.7:2.5)were prepared and the mechanisms to PVC were investigated by means of thermal analysis method.In this paper, bis(β-butyloxycarbonylethyl) tin dichlorides intermediate was synthesized by Sn powder, butyl acrylate reacted with HCl, HCl/hydrochloric acid and hydrochloric acid separately, and the effects of the reaction conditions such as the ratio of raw materials, temperature and reaction time to the component ratio of intermediate were studied. Results showed that the reaction temperature and the way to pump in HCl were the key factors, and the yield was over 90%. The intermediate was the mixture of (C4H9OCOCH2CH2)2SnCl2 and (C4H9OCOCH2CH2)SnCl3, and (C4H9OCOCH2CH2)2SnCl2 which accounted for 88.97% was the main component.Ester-tin(methyl acrylate) and ester-tin(butyl acrylate) were synthesized with Na2CO3 mixing solvents and transfer catalyst. The effects of synthesis methods, reaction temperature, reaction time, catalyst dosages and concentration of Na2CO3 aq. to the yield, Sn content and thermal stability were investgated. The components and structures of two products that produced by means of Na2CO3 aq. and NaHCO3 analyzed by HPLC, IR, and 1-NMR, and the reason of appearing precipitation was proposed. Static and dynamic thermal stability, transparency, rheologic properties of two products were investigated, and the mechanism to suppress PVC degredation was also analyzed by comparing with methyltin mercaptide.Results showed that the precipitation in ester-tin (methyl acrylate) synthesized by NaHCO3 was ester-tin hydroxide which was formed by the byproducts from the hydrolysis of bis(β-butyloxycarbonylethyl) tin dichlorides. Ester-tin (methyl acrylate) synthesized by Na2CO3 aq. was clear over 3 months, because in this reaction system, bis(β-butyloxycarbonylethyl) tin dichlorides reacted fully with mercaptoester catalyzed under transfer catalysist without ester-tin hydroxide was not formed in products. Thermal stability of the products made by Na2CO3 mixing solvents was better than that of making by NaHCO3. Ester-tin(butyl acrylate) synthesized by Na2CO3 mixing solvents was clear over 1 year, the concentration of Na2CO3 aq. was the most important of all the factors. The processing stability, transparency and flowing properties of two kinds of ester-tin were similar with methyltin mercaptide under PVC processing conditions.The synergism between ester-tin(methyl acrylate) with methyltin mercaptide, metal soaps, antioxidant bisphenol a and HLDs were investigated. How ester-tin (methyl acrylate)/methyltin mercaptide, ester-tin(methyl acrylate)/antioxidant bisphenol a/HLDs compound stabilizers to suppress the degradation process of PVC were analyzed. The dynamic thermal stability, transparency, and dynamic properties of compound ester-tin/PVC were also tested.Experimental results indicated that there was little synergism between ester-tin(methyl acrylate) and methyltin mercaptide, but the first stage pigmentation processing safety and transparency were improved; There were synergisms among barium stearate, calcium stearate and ester-tin(methyl acrylate), but zinc stearate not only had no synergistic effect but also could accelerate the degradation of PVC; Ester-tin(methyl acrylate)/bisphenol a/ HLDs modified by titanate (2:1:2.5) environmental compound stabilizers exhibited a better thermal stability, HLDs modified by titanate had not only a famous synergistic effect but also a better dispersity and consistency in PVC as well, so the thermal stability and mechanical properties of PVC composites were improved.