熱(re)封(feng)(feng)次(ci)數(shu)越(yue)(yue)多，熱(re)封(feng)(feng)強度越(yue)(yue)高，縱向熱(re)封(feng)(feng)次(ci)數(shu)取決于縱向焊棒的有(you)效長度和袋長之比。
橫向(xiang)熱(re)(re)(re)(re)封(feng)(feng)(feng)次(ci)數由機臺橫向(xiang)熱(re)(re)(re)(re)封(feng)(feng)(feng)裝置的組數決定。良(liang)好(hao)的熱(re)(re)(re)(re)封(feng)(feng)(feng)，要求熱(re)(re)(re)(re)封(feng)(feng)(feng)次(ci)數至少達(da)到兩次(ci)以上(shang)。相同(tong)結構和厚度(du)的復合(he)膜，復合(he)層間剝(bo)離(li)(li)度(du)越高，熱(re)(re)(re)(re)封(feng)(feng)(feng)強(qiang)(qiang)度(du)越大；對于(yu)復合(he)剝(bo)離(li)(li)強(qiang)(qiang)度(du)低的產品，焊(han)縫(feng)破壞(huai)往往是焊(han)縫(feng)處的復合(he)膜先層間剝(bo)離(li)(li)，致使由內面熱(re)(re)(re)(re)封(feng)(feng)(feng)層獨立承(cheng)受破壞(huai)拉力，而面層材(cai)料失(shi)去補(bu)強(qiang)(qiang)作用，致使焊(han)縫(feng)的熱(re)(re)(re)(re)封(feng)(feng)(feng)強(qiang)(qiang)度(du)由此大為(wei)降低；若(ruo)復合(he)層間剝(bo)離(li)(li)度(du)強(qiang)(qiang)，則不致發生焊(han)邊處層問的剝(bo)離(li)(li)，所測(ce)得(de)的實際熱(re)(re)(re)(re)封(feng)(feng)(feng)強(qiang)(qiang)度(du)就人得(de)多；在(zai)熱(re)(re)(re)(re)封(feng)(feng)(feng)內層為(wei)PE或OPP時，熱(re)(re)(re)(re)封(feng)(feng)(feng)強(qiang)(qiang)度(du)就比同(tong)樣厚度(du)的BOPP好(hao)得(de)多。