熱封次(ci)數越多，熱封強度越高，縱向熱封次(ci)數取(qu)決于縱向焊棒(bang)的有效(xiao)長(chang)度和袋長(chang)之比(bi)。
橫(heng)向熱(re)(re)封(feng)次(ci)(ci)數由(you)機臺橫(heng)向熱(re)(re)封(feng)裝置的組數決(jue)定。良好的熱(re)(re)封(feng)，要求熱(re)(re)封(feng)次(ci)(ci)數至少達到兩(liang)次(ci)(ci)以(yi)上(shang)。相同(tong)結構和厚(hou)度(du)(du)的復合膜，復合層(ceng)間剝離度(du)(du)越高，熱(re)(re)封(feng)強(qiang)(qiang)度(du)(du)越大；對(dui)于復合剝離強(qiang)(qiang)度(du)(du)低(di)的產品，焊(han)(han)縫(feng)(feng)破壞往往是焊(han)(han)縫(feng)(feng)處(chu)的復合膜先層(ceng)間剝離，致(zhi)(zhi)使由(you)內面熱(re)(re)封(feng)層(ceng)獨立承(cheng)受(shou)破壞拉(la)力(li)，而面層(ceng)材(cai)料失去補強(qiang)(qiang)作用，致(zhi)(zhi)使焊(han)(han)縫(feng)(feng)的熱(re)(re)封(feng)強(qiang)(qiang)度(du)(du)由(you)此大為降低(di)；若復合層(ceng)間剝離度(du)(du)強(qiang)(qiang)，則(ze)不致(zhi)(zhi)發生焊(han)(han)邊處(chu)層(ceng)問(wen)的剝離，所(suo)測(ce)得的實際(ji)熱(re)(re)封(feng)強(qiang)(qiang)度(du)(du)就人得多(duo)；在(zai)熱(re)(re)封(feng)內層(ceng)為PE或OPP時，熱(re)(re)封(feng)強(qiang)(qiang)度(du)(du)就比同(tong)樣厚(hou)度(du)(du)的BOPP好得多(duo)。