Zipper tape and packaging bag with zipper tape

Abstract

Since a rib having a thickness substantially equal to a thickness of each of first and second thick portions is provided in a cutting portion of a zipper tape, the first and second thick portions and the rib can be bonded to an inner surface when the zipper tape is bonded to a bag body. Accordingly, when tearing a packaging bag for opening, stress concentrates on a thin portion having a small tensile strength, so that the packaging bag can be cut at a single cutting position in the thin portion. Consequently, no cutting fragment is generated. Moreover, since a cutting line is positioned by the rib when tearing the packaging bag, the cutting line is not waved, so that the packaging bag can easily be torn with a linear cutting performance.

1 . A zipper tape comprising a pair of belt-like bases respectively having a male member and a female member, the male member and the female member being engageable to each other, wherein
 at least one of the pair of belt-like bases is provided with a cutting portion at an end thereof, the cutting portion comprising:   a pair of thick portions that are thicker than a thickness of the at least one of the pair of belt-like bases;   a thin portion that is provided between the pair of thick portions and is thinner than a thickness of each of the thick portions; and   a rib that projects from the thin portion and has substantially the same thickness as the thickness of each of the thick portions.   
     
     
         2 . The zipper tape according to  claim 1 , wherein
 the thickness of the rib is defined as a sum of a height of the rib projecting from the thin portion and the thickness of the thin portion, and   a ratio of the thickness of the rib to the thickness of each of the thick portions is from 0.8 to 1.2.   
     
     
         3 . The zipper tape according to  claim 1 , wherein
 a ratio of the thickness of each of the thick portions to the thickness (D1) of the thin portion is from 3 to 12.   
     
     
         4 . The zipper tape according to  claim 1 , wherein
 a bonding layer is provided on a surface of each of the belt-like bases, the pair of thick portions and the rib.   
     
     
         5 . The zipper tape according to  claim 4 , wherein
 the bonding layer is formed of a polyolefin resin having a melting point lower than that of a resin for the belt-like bases and the cutting portion.   
     
     
         6 . A packaging bag provided with a zipper tape comprising: a bag body having an opening through which contents are capable of being inserted; and the zipper tape according to  claim 1 , wherein
 the surface of each of the belt-like bases, the thick portions and the rib of the zipper tape are bonded to an inner surface of the opening.