Disposable Diaper Side Seal with Variable Density Dot Welding
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Solution Overview
Problem
Conventional underpants-type disposable diapers face challenges in achieving sufficient strength during use while ensuring ease of tearing, and the dot pattern design often results in fiber waste sticking in sealing devices, making cleanup difficult.
Innovation Solution
The diaper features a side seal section with a dot pattern where non-welded parts are placed on both sides of welded parts in the vertical direction, with varying densities of welding to balance strength and ease of tearing, and uses ultrasonic sealing to prevent fiber waste accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a dot pattern with increased welded parts is employed to achieve sufficient seal strength, then the seal strength is improved, but fiber waste of the non-woven fabric tends to stick in gaps between protrusions in the sealing device, making cleanup difficult
Solution Approach 1:
The side seal section is divided into multiple regions with different welding densities: a first region with a first dot pattern (lower welding density) and a second region with a second dot pattern (higher welding density). This segmentation allows different portions to serve different functions - the first region prioritizes ease of tearing while the second region provides enhanced seal strength where needed.
Solution Approach 2:
Different welding patterns are applied to different regions of the side seal section based on local requirements. The first region uses a sparser dot pattern suitable for areas requiring ease of tearing, while the second region uses a denser dot pattern for areas requiring higher seal strength, optimizing both performance characteristics in their respective locations.
2Ease of operation
If only non-woven fabrics of polypropylene are laminated in the side seal section to achieve ease of tearing, then the ease of tearing is improved, but the seal strength becomes insufficient compared to other areas
Solution Approach 1:
The side seal section incorporates regions with different material compositions and welding densities. The first region uses polypropylene non-woven fabric with lower welding density for ease of tearing, while the second region uses the same material but with higher welding density to provide sufficient seal strength where the fastening force is applied.
Solution Approach 2:
The side seal section is segmented into functional zones: a first region optimized for tearing initiation and a second region optimized for maintaining seal integrity during use. This segmentation allows each region to be optimized for its specific function without compromising the other.
3Strength
If a horizontal stripe pattern is used for welding in the side seal section, then the seal strength is maintained, but the tearing is more difficult compared to a dot pattern
Solution Approach 1:
The invention replaces the conventional horizontal stripe (linear) welding pattern with a dot (circular/curved) welding pattern. The dot pattern creates curved stress distribution and stress concentration points that facilitate easier tearing initiation while maintaining adequate seal strength through proper dot density and size control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design achieves both sufficient strength during use and ease of tearing while preventing fiber waste from sticking in the sealing device, maintaining cleanliness and efficiency in manufacturing.
Implementation Method 1
a front body part and a back body part are each weld-jointed together on both sides to form side seal sections
Data Source
AI summary
In a dot pattern, both sufficient strength during the use of a diaper and the ease of tearing can be achieved, while inhibiting sticking of fiber waste of a non-woven fabric in the sealing device. The problems can be solved by the underpants-type disposable diaper characterized by a side seal section 13 is formed in a dot pattern in which a plurality of rows of dot-shaped welded parts 13s, 13b, disposed with intervals in a vertical direction, are disposed in a transverse direction, and non-welded parts 13n, disposed all over in the transverse direction, are disposed on both sides of each welded part 13s, 13b, in the vertical direction; the side seal section 13 has at least partly in the vertical direction a non-densely welded region LD and a densely welded region HD; and each welded part 13b in the densely welded region HD is larger in area than each welded part 13s in the non-densely welded region LD.