熱(re)封(feng)次數(shu)(shu)越多，熱(re)封(feng)強度越高(gao)，縱(zong)向(xiang)熱(re)封(feng)次數(shu)(shu)取決于縱(zong)向(xiang)焊棒的有效(xiao)長(chang)度和袋(dai)長(chang)之比。
橫(heng)向熱(re)(re)封(feng)(feng)次數(shu)由機臺橫(heng)向熱(re)(re)封(feng)(feng)裝(zhuang)置(zhi)的(de)組數(shu)決(jue)定(ding)。良好(hao)的(de)熱(re)(re)封(feng)(feng)，要求熱(re)(re)封(feng)(feng)次數(shu)至少達到(dao)兩次以上。相同結構和厚度(du)(du)(du)的(de)復(fu)合膜，復(fu)合層(ceng)間(jian)剝(bo)(bo)離度(du)(du)(du)越(yue)高，熱(re)(re)封(feng)(feng)強(qiang)度(du)(du)(du)越(yue)大；對于復(fu)合剝(bo)(bo)離強(qiang)度(du)(du)(du)低的(de)產(chan)品(pin)，焊(han)縫(feng)破壞往往是焊(han)縫(feng)處(chu)的(de)復(fu)合膜先層(ceng)間(jian)剝(bo)(bo)離，致使由內面熱(re)(re)封(feng)(feng)層(ceng)獨立承(cheng)受破壞拉力(li)，而面層(ceng)材料失去補強(qiang)作(zuo)用(yong)，致使焊(han)縫(feng)的(de)熱(re)(re)封(feng)(feng)強(qiang)度(du)(du)(du)由此大為降低；若復(fu)合層(ceng)間(jian)剝(bo)(bo)離度(du)(du)(du)強(qiang)，則不(bu)致發(fa)生(sheng)焊(han)邊處(chu)層(ceng)問的(de)剝(bo)(bo)離，所測得(de)(de)的(de)實(shi)際熱(re)(re)封(feng)(feng)強(qiang)度(du)(du)(du)就人得(de)(de)多；在(zai)熱(re)(re)封(feng)(feng)內層(ceng)為PE或(huo)OPP時(shi)，熱(re)(re)封(feng)(feng)強(qiang)度(du)(du)(du)就比同樣厚度(du)(du)(du)的(de)BOPP好(hao)得(de)(de)多。