熱(re)(re)封(feng)(feng)次數(shu)越(yue)多，熱(re)(re)封(feng)(feng)強度越(yue)高，縱向熱(re)(re)封(feng)(feng)次數(shu)取決于縱向焊棒(bang)的有(you)效(xiao)長(chang)度和袋長(chang)之比(bi)。
橫向熱(re)封(feng)(feng)(feng)(feng)(feng)次數(shu)由機臺(tai)橫向熱(re)封(feng)(feng)(feng)(feng)(feng)裝置的(de)(de)組(zu)數(shu)決定。良(liang)好的(de)(de)熱(re)封(feng)(feng)(feng)(feng)(feng)，要求熱(re)封(feng)(feng)(feng)(feng)(feng)次數(shu)至(zhi)少達到兩次以上。相同(tong)結構(gou)和厚度(du)的(de)(de)復合(he)(he)膜(mo)，復合(he)(he)層(ceng)間(jian)剝(bo)(bo)離度(du)越高，熱(re)封(feng)(feng)(feng)(feng)(feng)強(qiang)(qiang)度(du)越大(da)；對于復合(he)(he)剝(bo)(bo)離強(qiang)(qiang)度(du)低(di)的(de)(de)產(chan)品，焊縫破壞往(wang)往(wang)是焊縫處的(de)(de)復合(he)(he)膜(mo)先層(ceng)間(jian)剝(bo)(bo)離，致使(shi)由內面(mian)熱(re)封(feng)(feng)(feng)(feng)(feng)層(ceng)獨立(li)承受破壞拉(la)力，而面(mian)層(ceng)材料失去補強(qiang)(qiang)作用，致使(shi)焊縫的(de)(de)熱(re)封(feng)(feng)(feng)(feng)(feng)強(qiang)(qiang)度(du)由此大(da)為降低(di)；若復合(he)(he)層(ceng)間(jian)剝(bo)(bo)離度(du)強(qiang)(qiang)，則不致發生焊邊(bian)處層(ceng)問的(de)(de)剝(bo)(bo)離，所測得(de)的(de)(de)實際熱(re)封(feng)(feng)(feng)(feng)(feng)強(qiang)(qiang)度(du)就人得(de)多；在(zai)熱(re)封(feng)(feng)(feng)(feng)(feng)內層(ceng)為PE或(huo)OPP時，熱(re)封(feng)(feng)(feng)(feng)(feng)強(qiang)(qiang)度(du)就比(bi)同(tong)樣(yang)厚度(du)的(de)(de)BOPP好得(de)多。