抗冲聚丙烯EP533N生产工艺优化

Production process optimization of anti-impact polypropylene EP 533 N

针对高熔体流动速率抗冲聚丙烯(PP,牌号为EP 533 N)存在的冲击强度偏高、弯曲应力偏低等问题,从优化助催化剂三乙基铝(TEAL)/外给电子体二环戊基二甲氧基硅烷(Donor-D)(简称T/D,质量比,下同),气相反应器中的气相组分配比和乙烯加入质量分数等工艺参数入手,对中国石油兰州石化公司30万t/a的PP装置生产工艺进行了调整。结果表明:在其他操作条件相对稳定的情况下,随着T/D的降低,均聚PP粉料等规度提高,产品弯曲应力增加,冲击强度下降;结合装置稳定运行和现有的生产条件,控制乙烯/(乙烯+丙烯)(摩尔比)不小于0.30,高压闪蒸罐温度为75~77℃,可以使产品具有良好韧性;在气相反应器料位基本相同,PP粉料停留时间相近的条件下,将乙烯设定值(质量分数)降至11.3%,可获得冲击强度约为9.0 kJ/m2,弯曲应力约为1300 MPa的刚性与韧性相对平衡的产品。

Aiming at the defects of the high melt flow rate anti-impact polypropylene(PP,EP 533 N),such as high impact strength and low bending stress,a 0.3 Mt/a PP unit of Lanzhou Petrochemical Company,PetroChina,was adjusted to the optimum process parameters on aspects of co-catalyst triethylaluminum(TEAL)/external electron donor dicycloamyl dimethoxy silane(Donor-D)(T/D,mass ratio),the distribution ratio of gas phase and the mass fraction of ethylene addition in the gas phase reactor.The results showed that under the conditions of other operating conditions were relatively stable,with the decreasing of T/D,the isotacticity of PP powder had increased,the product′s bending stress had improved and the impact strength had decreased.Combined with the stable operation of the unit and the existing production conditions,the product could reach better toughness by controlling the ethylene/(ethylene+propylene)(molar ratio)not less than 0.30 and the temperature of high-pressure flash tank at 75-77℃.Under the conditions of the PP powder level of the gas phase reactor was basically the same and the residence time of PP powder was similar,when the ethylene setting value(mass fraction)was reduced to 11.3%,the product with the impact strength of 9.0 kJ/m2 and the bending stress of 1300 MPa could be obtained,which rigidity and toughness could achieve a relative balance.