塑料薄膜的生產工藝(yi)

對塑料薄(bo)膜(mo)的(de)生產(chan)(chan)工藝(yi)而(er)言，共有(you)擠(ji)出吹(chui)膜(mo)法、擠(ji)出流涎(xian)(xian)法、溶(rong)(rong)劑(ji)(ji)流涎(xian)(xian)法、壓延法等多(duo)種(zhong)，而(er)這些工藝(yi)之中，擠(ji)出流涎(xian)(xian)法生產(chan)(chan)的(de)薄(bo)膜(mo)由于(yu)縱橫向(xiang)性(xing)(xing)(xing)(xing)能平(ping)衡、無(wu)內應力(li)、熱(re)封(feng)(feng)(feng)(feng)性(xing)(xing)(xing)(xing)優的(de)特點最(zui)適宜用(yong)(yong)(yong)(yong)于(yu)熱(re)封(feng)(feng)(feng)(feng)。但是擠(ji)出流涎(xian)(xian)設備(bei)(bei)投資(zi)大，限(xian)制(zhi)了實際(ji)的(de)使(shi)(shi)(shi)(shi)用(yong)(yong)(yong)(yong)率，使(shi)(shi)(shi)(shi)用(yong)(yong)(yong)(yong)面較(jiao)(jiao)廣(guang)的(de)是擠(ji)出吹(chui)膜(mo)法生產(chan)(chan)的(de)熱(re)封(feng)(feng)(feng)(feng)膜(mo)，應當注意的(de)是擠(ji)出吹(chui)膜(mo)時的(de)拉(la)伸比(bi)和(he)牽(qian)(qian)引比(bi)都應當較(jiao)(jiao)小(xiao)一點，且二(er)者應平(ping)衡，防止因拉(la)伸比(bi)或牽(qian)(qian)引比(bi)過(guo)大，引起過(guo)多(duo)的(de)塑料分(fen)子因拉(la)力(li)作用(yong)(yong)(yong)(yong)而(er)產(chan)(chan)生定(ding)向(xiang)結晶，使(shi)(shi)(shi)(shi)薄(bo)膜(mo)喪失熱(re)封(feng)(feng)(feng)(feng)性(xing)(xing)(xing)(xing)。在(zai)生產(chan)(chan)耐熱(re)性(xing)(xing)(xing)(xing)較(jiao)(jiao)好(hao)的(de)聚丙烯熱(re)封(feng)(feng)(feng)(feng)用(yong)(yong)(yong)(yong)膜(mo)時，應使(shi)(shi)(shi)(shi)用(yong)(yong)(yong)(yong)水冷卻法的(de)下吹(chui)法擠(ji)吹(chui)膜(mo)，才(cai)能使(shi)(shi)(shi)(shi)PP膜(mo)有(you)良好(hao)的(de)熱(re)封(feng)(feng)(feng)(feng)和(he)透明性(xing)(xing)(xing)(xing)。溶(rong)(rong)劑(ji)(ji)流涎(xian)(xian)法因需(xu)要(yao)使(shi)(shi)(shi)(shi)用(yong)(yong)(yong)(yong)到大量的(de)溶(rong)(rong)劑(ji)(ji)，成本貴，溶(rong)(rong)劑(ji)(ji)回收設備(bei)(bei)大、投資(zi)大、耗費大，一般極少使(shi)(shi)(shi)(shi)用(yong)(yong)(yong)(yong)，只(zhi)在(zai)生產(chan)(chan)極薄(bo)、高(gao)性(xing)(xing)(xing)(xing)能電子包(bao)裝膜(mo)時才(cai)使(shi)(shi)(shi)(shi)用(yong)(yong)(yong)(yong)。壓延法只(zhi)使(shi)(shi)(shi)(shi)用(yong)(yong)(yong)(yong)在(zai)PVC薄(bo)膜(mo)、片材(cai)上(shang)，對熔(rong)體流動性(xing)(xing)(xing)(xing)很好(hao)的(de)聚烯烴塑料而(er)言，只(zhi)適用(yong)(yong)(yong)(yong)于(yu)無(wu)機(ji)填充量較(jiao)(jiao)大時才(cai)使(shi)(shi)(shi)(shi)用(yong)(yong)(yong)(yong)。