熱(re)封(feng)次數(shu)越(yue)(yue)多，熱(re)封(feng)強度(du)越(yue)(yue)高，縱向熱(re)封(feng)次數(shu)取決于(yu)縱向焊棒的(de)有效長度(du)和袋(dai)長之比(bi)。
橫(heng)向熱(re)(re)封(feng)(feng)(feng)(feng)次數由機臺橫(heng)向熱(re)(re)封(feng)(feng)(feng)(feng)裝置(zhi)的組數決定。良好的熱(re)(re)封(feng)(feng)(feng)(feng)，要求熱(re)(re)封(feng)(feng)(feng)(feng)次數至少(shao)達到兩次以上(shang)。相同結構和厚(hou)度(du)(du)的復(fu)合(he)膜，復(fu)合(he)層(ceng)(ceng)間剝(bo)(bo)(bo)離(li)度(du)(du)越高，熱(re)(re)封(feng)(feng)(feng)(feng)強(qiang)度(du)(du)越大(da)；對于復(fu)合(he)剝(bo)(bo)(bo)離(li)強(qiang)度(du)(du)低的產品，焊(han)(han)縫(feng)(feng)破(po)壞往往是焊(han)(han)縫(feng)(feng)處的復(fu)合(he)膜先(xian)層(ceng)(ceng)間剝(bo)(bo)(bo)離(li)，致使由內面熱(re)(re)封(feng)(feng)(feng)(feng)層(ceng)(ceng)獨立承受破(po)壞拉力，而面層(ceng)(ceng)材料失(shi)去補強(qiang)作用，致使焊(han)(han)縫(feng)(feng)的熱(re)(re)封(feng)(feng)(feng)(feng)強(qiang)度(du)(du)由此(ci)大(da)為(wei)降低；若(ruo)復(fu)合(he)層(ceng)(ceng)間剝(bo)(bo)(bo)離(li)度(du)(du)強(qiang)，則不致發生(sheng)焊(han)(han)邊處層(ceng)(ceng)問的剝(bo)(bo)(bo)離(li)，所測得的實際熱(re)(re)封(feng)(feng)(feng)(feng)強(qiang)度(du)(du)就人得多；在熱(re)(re)封(feng)(feng)(feng)(feng)內層(ceng)(ceng)為(wei)PE或OPP時，熱(re)(re)封(feng)(feng)(feng)(feng)強(qiang)度(du)(du)就比(bi)同樣厚(hou)度(du)(du)的BOPP好得多。