As described in JP-A-U-61-94536 (the term "JP-A-U" as used herein means an "unexamined published Japanese utility model application") and as shown in FIG. 10, the fastener tape 20 in a conventional diaper 1 comprises a tape substrate 21, a first pressure-sensitive adhesive area 22 provided on one side of the substrate 21 in a substrate part 21a which is close to one end of the substrate 21, and a second pressure-sensitive adhesive area 24 provided on the other side of the substrate 21 in a substrate part 21b which is close to the other end of the substrate 21. The first pressure-sensitive adhesive area 22 is formed by coating the part 21a with a pressure-sensitive adhesive at a uniform thickness over the whole surface and serves to fix the tape substrate 21 to a top sheet 2a in a back part 2 of the diaper 1, while the second pressure-sensitive adhesive area 24 is formed by coating the part 21b with a pressure-sensitive adhesive at a uniform thickness over the whole surface and serves to bond the tape substrate 21 to a center tape 23 provided in a front part 3 of the diaper 1.
The fastener tape 20 receives external peeling forces when an infant or person who is wearing the diaper 1 walks or fingers the back part 2. There are cases where due to such external forces, the fastener tape 20 peels off the back part 2 or other part during use of the diaper 1. Further, there is another problem that when the tape substrate part 21a close to one end of the tape substrate 21 is pulled away from the front part 3 in order to refasten the diaper, the first pressure-sensitive adhesive area 22 peels off the back part 2 by the pulling force.
The above-described undesirable peeling has occurred frequently particularly in diapers in which the fastener tape 20 is bonded to a top sheet 2a in the back part 2, because the top sheet 2a is generally formed by a nonwoven fabric and, hence, the fastener tape 20 shows poor adhesion to this top sheet 2a.
Although the poor adhesion may be improved by increasing the thickness of the pressure-sensitive adhesive layer in the first pressure-sensitive adhesive area 22 or second pressure-sensitive adhesive area 24 in the fastener tape 20 to thereby increase the peel strength from the diaper 1, this expedient is disadvantageous in that the pressure-sensitive adhesive should be used in an increased amount and this raises the cost of diaper production.
USPTO Backgrounds
USPTO Backgrounds