Water-absorbent sheet composite
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Solution Overview
Problem
There is a demand for a water-absorbent sheet structure that is thin, provides excellent liquid permeability, has a small amount of liquid re-wet, and minimizes liquid leakage, while also offering improved body fitability and eco-friendliness for use in absorbent articles like light incontinence pads.
Innovation Solution
A water-absorbent sheet structure comprising a water-absorbent resin and adhesive sandwiched between a water-permeable nonwoven fabric and a water-retaining nonwoven fabric, where the upper nonwoven fabric has a water-permeation rate of 10 seconds or less and the lower nonwoven fabric has a water absorption of 250 g/m² or more, ensuring fast liquid permeability and reduced liquid leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a water-absorbent sheet structure uses conventional materials and design, then it achieves sufficient absorbent capacity, but it results in increased thickness and weight
Solution Approach 1:
The patent changes the physical and chemical parameters of the nonwoven fabrics, specifically controlling the water permeation rate to 10 seconds or less and the water absorption to 250 g/m² or more. These parameter optimizations enable the achieve excellent liquid permeability and minimal re-wet without increasing thickness
Solution Approach 2:
The patent uses composite nonwoven fabric structures with specific compositions - the upper nonwoven fabric comprises hydrophilic synthetic fibers (5-50 mass%) and hydrophobic synthetic fibers (50-95 mass%), while the lower nonwoven fabric uses different fiber compositions. This composite structure achieves both thin profile and high absorbent capacity
2Speed
If the upper nonwoven fabric has high water permeability, then fast liquid permeation is achieved, but liquid re-wet increases
Solution Approach 1:
The patent precisely controls the water permeation rate parameter to 10 seconds or less while simultaneously controlling the water absorption parameter to 250 g/m² or more. This dual parameter optimization resolves the contradiction by enabling fast permeation while minimizing re-wet through optimized capillary action and absorption kinetics
Solution Approach 2:
The patent applies different local qualities to the upper and lower nonwoven fabrics. The upper fabric has specific hydrophilic/hydrophobic fiber ratios optimized for fast permeation, while the lower fabric has different composition optimized for absorption. This local differentiation allows each layer to perform its specific function optimally without compromising the other
3Quantity of substance
If natural materials like crushed pulp fibers are used to improve absorbency, then liquid absorption capacity increases, but environmental sustainability decreases due to long growth time
Solution Approach 1:
The patent changes the material composition parameters by using predominantly synthetic fibers (95-99 mass% in preferred embodiments) instead of natural fibers, while achieving equal or superior absorption capacity through optimized water permeation rate and water absorption parameters. This eliminates the need for resource-intensive natural materials
Solution Approach 2:
The patent employs synthetic fibers that can be produced rapidly and sustainably without the long growth cycles required for natural fibers like wood pulp. These synthetic materials provide the necessary absorbent functionality without the environmental cost of deforestation and long cultivation times
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
The structure achieves fast liquid permeability, minimal liquid re-wet, and low leakage, making it suitable for thin, hygienic absorbent materials with improved body fitability and environmental sustainability.
Implementation Method 1
an upper nonwoven fabric of the water-absorbent sheet structure is a water-permeable nonwoven fabric having a water permeation rate of 10 s or 25 less
Implementation Method 2
a lower nonwoven fabric of the water-absorbent sheet structure is a water-retaining nonwoven fabric having an amount of water absorption of 250 g/m 2
Data Source
Figure 1~2
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Figure 5~6
AI summary
A water-absorbent sheet structure (10) including a structure in which an absorbent layer (13) containing a water-absorbent resin (12) and an adhesive (11) is sandwiched with nonwoven fabrics from an upper side and a lower side of the absorbent layer, the water-absorbent sheet structure (10) comprising (1) an upper nonwoven fabric (14) which is a water-permeable nonwoven fabric having a water permeation rate of 10 s or less; and (2) a lower nonwoven fabric (15) which is a water-retaining nonwoven fabric having an amount of water absorbed of 250 g/m2 or more. The water-absorbent sheet structure (10) of the present invention is thin and is capable of sufficiently exhibiting water-absorbent capacities such as fast liquid permeability, a small amount of liquid re-wet, and a small amount of liquid leakage. Therefore, the water-absorbent sheet structure (10) according to the present invention is used for an absorbent material, whereby hygienic materials which are thin and have excellent body fittability can be provided.