Patent ID: 7246415

Claim:
An interlocking device comprising a pair of male and female profiles, wherein: (a) each of said male and female profiles comprises a non-heat-sealing part to a bag body and a heat-sealing part to a bag body, (b) said non-heat sealing part comprises a polypropylene type resin composition (A) having a main melting peak temperature observed by differential scanning calorimetry (DSC), of not less than 150° C. and a melt flow rate at 230° C. of 0.5 g/10 min. to 20 g/10 min.; (c) said heat sealing part comprises a polypropylene type resin composition (B) having a main melting peak temperature observed by DSC, of not less than 140° C. and a melt flow rate at 230° C. of 0.1 g/ 10 min. to 20 g/10 min.; (d) the main melting peak temperature of composition (B) is at least 10° C. lower than that of composition (A); and (e) the interlocking device does not change more than 3% from its original dimension after being immersed in a 135° C. glycerin bath for 15 minutes and removed from the bath and allowed to cool for 30 minutes.