熱封(feng)(feng)次數(shu)(shu)越(yue)多，熱封(feng)(feng)強度越(yue)高，縱(zong)(zong)向(xiang)(xiang)熱封(feng)(feng)次數(shu)(shu)取決于縱(zong)(zong)向(xiang)(xiang)焊棒的有效(xiao)長度和袋長之比。
橫向熱(re)(re)封(feng)(feng)(feng)(feng)次(ci)數由機(ji)臺(tai)橫向熱(re)(re)封(feng)(feng)(feng)(feng)裝置(zhi)的組(zu)數決定。良好(hao)的熱(re)(re)封(feng)(feng)(feng)(feng)，要求熱(re)(re)封(feng)(feng)(feng)(feng)次(ci)數至少(shao)達到兩次(ci)以上(shang)。相同結構(gou)和(he)厚度(du)的復(fu)合膜，復(fu)合層(ceng)間剝(bo)(bo)離(li)(li)度(du)越高，熱(re)(re)封(feng)(feng)(feng)(feng)強(qiang)(qiang)度(du)越大；對于復(fu)合剝(bo)(bo)離(li)(li)強(qiang)(qiang)度(du)低(di)的產品，焊(han)(han)縫破壞往(wang)(wang)往(wang)(wang)是焊(han)(han)縫處的復(fu)合膜先層(ceng)間剝(bo)(bo)離(li)(li)，致(zhi)使由內面熱(re)(re)封(feng)(feng)(feng)(feng)層(ceng)獨立(li)承受破壞拉力，而(er)面層(ceng)材料失去(qu)補強(qiang)(qiang)作用(yong)，致(zhi)使焊(han)(han)縫的熱(re)(re)封(feng)(feng)(feng)(feng)強(qiang)(qiang)度(du)由此大為降低(di)；若復(fu)合層(ceng)間剝(bo)(bo)離(li)(li)度(du)強(qiang)(qiang)，則不致(zhi)發(fa)生焊(han)(han)邊處層(ceng)問(wen)的剝(bo)(bo)離(li)(li)，所測(ce)得(de)的實(shi)際熱(re)(re)封(feng)(feng)(feng)(feng)強(qiang)(qiang)度(du)就(jiu)人得(de)多；在熱(re)(re)封(feng)(feng)(feng)(feng)內層(ceng)為PE或OPP時，熱(re)(re)封(feng)(feng)(feng)(feng)強(qiang)(qiang)度(du)就(jiu)比同樣厚度(du)的BOPP好(hao)得(de)多。