发布时间 : 星期二 文章河北科技大学高分子材料专业外语翻译更新完毕开始阅读
的苯乙烯的本体聚合取代了悬浮聚合，ABS本体聚合代替了乳液聚合。然而，现代气相法聚乙烯似乎走相反的趋势。看来，相比于使用本体聚合，聚合技术更多倾向于消除溶剂和悬浮液。当单体是聚合物的溶剂时，人们选择本文中所描述的本体聚合。当单体不是溶剂时，如聚乙烯和聚丙烯，人们使用悬浮和淤浆过程。这样，可避免高粘性的连续相，又不需引入外来物质。
UNIT 13 General Description of the VC Suspension
Polymerization Process
第十三单元 氯乙烯悬浮聚合过程概述
By far majority of PVC is produced via the suspension route.In this process the vinyl chloride monomer is suspended, as liquid droplets, in a continuous water phase by a combination of vigorous agitation and the presence of a protective colloid (dispersant or suspending agent). A monomer soluble free radical initiator is used such that has been shown to be equivalent to that found in bulk polymerization.
绝大多数聚氯乙烯是采用悬浮聚合工艺生产的。这个工艺中，在强力搅拌和保护单体存在的联合作用下，氯乙烯单体以液滴形式悬浮在水连续相中。溶解自由基引发剂的单体（液滴）表现出与在本体聚合等同的行为。
Commercial plants are based on batch reactors, the size of which have increased progressively over the years. the original plants built during the 1940s usually consisted of 1000 gallon reactors. During the 1950s and 1960s this increased to 3000-5000 gallon and subsequently, during the early 1970s, 29000gallon reactor systems were developed by Shin Estu② and up to 44000 gallon (200m) by the German company Huls. At the present time few new plants being built consist of reactor of less than 15000 gallon capacity, having a batch size of about 25 tones of
monomer. Smaller reactors were often glass lined to give a smooth that would resist the laydown of deposits on the walls.③ Larger reactors are usually of polished stainless steel.
1950-1960期间尺寸增大到3000-5000加仑，后来在19世纪70年代初期，由信月公司开发了29000加仑反应器系统，后来德国的Huls公司又增加到44000（200m2）加仑的反应器体积。商用设备是基于间歇式反应器，与19世纪40年代建造的1000加仑反应器相比，反应器的尺寸逐年增加。目前正建造的新反应器很少有小于15000加仑的，约25吨单体所需要的釜尺寸。小型的（氯乙烯悬浮聚合）反应器内壁搪拨玻璃使壁面光滑，以防止聚合物粘壁。而大的反应器通常是抛光的不锈钢（内壁）。
The polymerization of vinyl chloride is a very exothermic reaction and so the ability to remove heat is usually the limiting factor in attempting to minimize reaction times. As the size of reactors has increased the surface area to volume ratio has decreased thus aggravating the problem. Internal cooling coils are not usually used as they would attract deposits and be difficult to clean and thus have an adverse effect on product properties. The problem is often overcome by the use of chilled water or the fitting of a reflux condenser which, via the continued refluxing of vinyl chloride monomer, utilises its latent heat of vapourisation for cooling purposes.
氯乙烯的聚合反应是放热反应，所以移走热量的能力常常是使反应时间最小化的限制因素。随着反映其尺寸的增加，比表面积减小，从而使（散热）问题更严重。通常不采用内部的冷却旋管（进行冷却），因为这些管路很容易沉积而且很难清洗，对产品质量的影响是负面的。解决问题的方法是采用冷冻水或安装回流冷凝器，回流冷凝器连续回流氯乙烯单体，利用单体的蒸发潜热冷却反应物料。
Cold water is usually charged to the reactor first although it is sometimes preheated. The pH regulator is then added followed by the dispersant (s) are sprinkled onto the surface of the aqueous phase immediately before sealing the reactor which is then evacuated to remove oxygen as this can increase polymerization time and affect product properties. When evacuation is complete the vinyl chloride is charged and heat-up of the reactor contents commenced. Reactor temperature, which is the main controlling factor for product molecular weight, is commonly in the range 50-70℃ resulting in reactor pressures of 100-165 psig. The trend is towards the operation of large closed reactors which are only opened for maintenance or, possibly, occasional cleaning operations. In this case all ingredients are charged as solutions or dispersions and there would generally be no need for the evacuation step.
冷却水通常先被加入反应器中，尽管这样有时可能被预热。然后安装pH计，接着立即将分散剂喷洒到液相表面，在密封反应器之前，将氧气排除，因为氧气会增加聚合时间而且影响产物的性质。当氧气排除结束后，填充氯乙烯，开始反应物料的加热。反应器温度，是控制产物分子量的因素，通常在50-70℃，导致反应器压力为100-165 psig。反应器的大型化封闭式操作是发展方向，仅仅在维护或偶然的清理时才打开聚合釜。在这种场合下，所有的物料以溶液或分散体系的方式被填充，因此不需要排除空气的步骤。
When the desired conversion has been reached, usually 75%-95%, the reaction can be chemically short-stopped if required and the bulk of the remaining monomer recovered. The product slurry is then stripped down to very low residual vinyl chloride levels by treatment at elevated temperatures, either in the reactor or similar vessel, or by contact with steam in a countercurrent mutilate stripping tower. The slurry is then dewatered by centrifuging and the resulting wet cake dried, commonly on
a multi-stage flash drier, although a wide variety of different drier types is used by various manufactures. After drying, the product is passed through some kind of scalping screen to remove extraneous large particles before bagging or loading to bulk road tankers.
当达到理想的转换率，通常为75-95%，如果需要的话，反应可以被停下来，而且剩余单体的大部分被补充。通过在提高温度情况下处理，不是在反应器中，就是在逆流气提塔与水蒸气接触，淤浆产物被脱出单体到非常低的氯乙烯残留水平。然后采用离心过滤将淤浆脱水，将产生的湿滤饼用多步急骤干燥机进行干燥，尽管不同的企业采用不同的干燥器类型。干燥以后，产物通过筛份设备移开无关的大颗粒，然后包装，装填到大的油罐汽车。
14 Styrene-Butadiene Copolymer 第十四单元 丁二烯-苯乙烯共聚物
The synthetic rubber industry, based on the free-radical emulsion process, was created almost overnight during World War II. Styrene-butadiene (GR-S) rubber crated at that time gives such good tire treads that natural rubber has never regained this market.
合成橡胶工业，以自由基乳液过程为基础，在第二次世界大战期间几乎很快地形成。那时，丁苯橡胶制造的轮胎性能相当优越，使天然橡胶在市场黯然失色。
This mixture is heated with stirring and at 50℃ gives conversions of 5%~6% per hour. Polymerization is terminated at 70%~75% conversion by addition of a “short-stop”, such as hydroquinone (approximately 0.1 part), to quench radicals and prevent excessive branching and microgel formation. Unreacted butadiene is removed by flash distillation, and syrene by steam-stripping in a column. After addition of an antioxidant, such as N-phenyl-β-naphthylamine (PBNA)