【摘要】：氯化聚氯乙烯是聚氯乙烯經(jīng)氯化得到的一種新型樹脂,是一種重要的聚氯乙烯改性產(chǎn)品。氯化聚氯乙烯除了擁有一些聚氯乙烯的優(yōu)良性能以外,還具有很多優(yōu)良性能如耐腐蝕、耐熱寒、阻燃以及較高的機(jī)械強(qiáng)度等。其在塑料、建材、醫(yī)學(xué)、電氣、農(nóng)業(yè)、涂料、造紙、船舶、包裝等方面有著較為廣泛的應(yīng)用。 國內(nèi)外大都采用水相懸浮法工藝生產(chǎn)氯化聚氯乙烯。通過高溫、加壓、加氧化劑等手段提高產(chǎn)品氯含量,但同時(shí)也會導(dǎo)致分子鏈斷裂,使產(chǎn)品分子量嚴(yán)重減小,導(dǎo)致產(chǎn)品的一些機(jī)械性能下降,制約了氯化聚氯乙烯的使用。采用氣固相法可以使氯化反應(yīng)在較低的溫度進(jìn)行,同時(shí)可以保證產(chǎn)品的氯含量,更重要的是,氣固相法反應(yīng)條件較為溫和,且不添加氧化劑幫助氯化,因此反應(yīng)中產(chǎn)品分子鏈的斷裂得到了有效的控制,產(chǎn)品分子量指標(biāo)可以保持在較高的水平,滿足實(shí)際應(yīng)用中對其機(jī)械性能的要求。另外,氣固相法工藝不需要處理大量廢水,經(jīng)濟(jì)環(huán)保,屬于綠色反應(yīng)工藝。 本文的研究內(nèi)容即為采用氣固相法制備氯化聚氯乙烯,考察了反應(yīng)時(shí)間、反應(yīng)溫度、通氯量及攪拌速率等對產(chǎn)品氯含量及產(chǎn)物分子量的影響,并給出了優(yōu)化后的反應(yīng)工藝。結(jié)果表明：升高溫度、延長反應(yīng)時(shí)間均有利于產(chǎn)品的氯含量增加；溫度升高會使數(shù)均分子量略有所下降,重均分子量有所增加；延長反應(yīng)時(shí)間可以使數(shù)均和重均分子量都有所增加；產(chǎn)品的氯含量會隨著通氯量的增加而增加,并且在某一值下達(dá)到飽和；攪拌速率對產(chǎn)品的影響相對較小。在氯化反應(yīng)中,增加了預(yù)氯化過程,可以提高聚氯乙烯的耐熱性能,使其可在較高溫度下進(jìn)行氯化,氯化效果優(yōu)于一步氯化。優(yōu)化后的工藝條件為：預(yù)氯化時(shí)間1h,預(yù)氯化溫度55℃,氯化溫度100℃,氯化時(shí)間6h,氯氣流量500mL/min,攪拌速率80r/min. 本文還對較為優(yōu)化的工藝條件下所制得的產(chǎn)品的各項(xiàng)指標(biāo)進(jìn)行了測定,如氯含量,表觀密度,揮發(fā)組分和分子量等。測試結(jié)果表明,該方法所得產(chǎn)品的一些性能指標(biāo)已經(jīng)滿足某些國內(nèi)企業(yè)的水相法的產(chǎn)品指標(biāo),部分性能大大超過了相關(guān)指標(biāo),并十分接近國外的相關(guān)工藝指標(biāo)。 實(shí)驗(yàn)中采用了自旋式反應(yīng)設(shè)備應(yīng)用于氣固相法制備氯化聚氯乙烯,代替?zhèn)鹘y(tǒng)的機(jī)械攪拌,可以使產(chǎn)品氯化均勻,性能良好。 本文還進(jìn)一步考察了常壓低溫下聚氯乙烯顆粒內(nèi)部的氯化反應(yīng)動力學(xué),推導(dǎo)得出該條件下的氣固相反應(yīng)動力學(xué)方程。并計(jì)算出不同溫度下的表觀反應(yīng)速率常數(shù)。最后通過阿倫尼烏斯方程計(jì)算出反應(yīng)的表觀活化能和指前因子,反應(yīng)表觀活化能為Ea=22.118kJ/mol,指前因子A=0.001355 (mol-m-3)-1·s-1,
[Abstract]:Chlorinated polyvinyl chloride (PVC) is a new type of resin obtained by chlorination of PVC, which is an important modified product of PVC. In addition to some excellent properties of PVC, chlorinated PVC also has many excellent properties such as corrosion resistance, heat resistance and cold resistance, flame retardancy and high mechanical strength. It is widely used in plastics, building materials, medicine, electricity, agriculture, paint, paper making, ship, packaging and so on. Chlorinated polyvinyl chloride (PVC) is produced by aqueous suspension process at home and abroad. By means of high temperature, pressure and oxidant, the chlorine content of the product is increased, but at the same time, the molecular chain breakage will be caused, the molecular weight of the product will be reduced seriously, and some mechanical properties of the product will be decreased, which will restrict the use of chlorinated polyvinyl chloride. The reaction of chlorination can be carried out at a lower temperature by gas-solid method, at the same time, the chlorine content of the product can be guaranteed. More importantly, the reaction conditions of the gas-solid method are mild and the oxidant is not added to help chlorination. Therefore, the molecular chain breakage of the product can be effectively controlled, and the molecular weight index of the product can be kept at a higher level, which can meet the requirements of its mechanical properties in practical application. In addition, the gas-solid process does not need to treat a large number of wastewater, economic and environmental protection, is a green reaction process. In this paper, chlorinated polyvinyl chloride was prepared by gas-solid method. The effects of reaction time, reaction temperature, chlorine flux and stirring rate on the chlorine content and molecular weight of the product were investigated, and the optimized reaction process was given. The results showed that increasing the temperature and prolonging the reaction time were beneficial to the increase of chlorine content, and the molecular weight of the product decreased slightly and the weight average molecular weight increased with the increase of temperature. When the reaction time is prolonged, the number average and weight average molecular weight can be increased, the chlorine content of the product will increase with the increase of chlorine flux, and reach saturation at a certain value, and the effect of stirring rate on the product is relatively small. In the chlorination reaction, the thermal resistance of PVC can be improved by adding prechlorination process, and the chlorination effect is better than that of one-step chlorination. The optimized conditions were as follows: prechlorination time 1 h, prechlorination temperature 55 鈩，

本文編號：2303407