高透明热收缩薄膜专用LDPE 2320D的性能改进

摘要

In order to improve the properties of low density polyethylene(LDPE)2320D for heat shrinkage films,the polymerization process parameters for producing 2320D were optimized as follows:the reaction pressure ranged from 265 MPa to 270 MPa,the temperatures of the four reaction zones were 285-290,290-295, 290-295,285-290 ℃,and propionaldehyde and propylene complex acted as relative molecular mass regulator. The results show that 2320D produced with the optimal process has the degree of long chain branching of 1.189-1.218/1 000 C,degree of branching of 14.5-15.0/1 000 C and haze of its film of 12.3%. The degree of branching and long chain branching of the product is improved. The transverse heat shrinkage rate of the blown film made of 2320D produced with optimal process is 35.7% at a constant temperature of 120 ℃ in 60 seconds,which is increased by 6.0 percent compared to that of the blown film made of 2320D produced before optimization,solving the problem of low transverse heat shrinkage rate of the films made of 2320D.%为改进热收缩薄膜专用低密度聚乙烯（LDPE）2320D的性能，优化了聚合工艺参数：反应压力为265～270MPa，4个反应区的峰温依次为285～290，290～295，290～295，285～290℃，丙醛与丙烯复配作相对分子质量调节剂。结果表明：优化聚合工艺后，所产2320D的长链支化度为1.189～1.218个/1000C、支化度为14.5～15.0个/1000C，薄膜雾度为12.3%，其支化度及长链支化度有所提高。优化聚合工艺后，用2320D吹塑的薄膜在120℃的恒温条件下，60s的横向热收缩率为35.7%，较用优化前所产2320D吹塑的薄膜提高6.0%，解决了薄膜横向热收缩率低的问题。