Cotton Fiber Nonwoven Surface Sheet for Absorbent Articles
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Solution Overview
Problem
Absorbent articles with front-surface sheets made of cotton fibers face issues with water retention and sideward urine leakage when absorbing medium to high volumes of urine, leading to discomfort and skin problems during long-hour wear.
Innovation Solution
A spunlace nonwoven fabric front-surface sheet composed entirely of cotton fibers, coated with a water repellent agent and featuring longitudinal and lateral streaks with specific fiber density and opening configurations, combined with a synthetic fibers-free pulp fiber and superabsorbent polymer absorber, to minimize water retention and promote urine diffusion in the longitudinal direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the front-surface sheet is made of cotton fibers to provide soft texture and skin comfort, then the texture felt to be as soft as underwear is achieved, but the liquid retainability increases causing stickiness and skin problems during long-hour wear
Solution Approach 1:
The front-surface sheet is designed with numerous front-face/back-face penetrating openings that allow liquid to pass through quickly. These openings create a porous structure that reduces liquid retention on the surface while maintaining the cotton fiber composition for skin comfort.
Solution Approach 2:
The water absorbing capacity of the skin-contacting face is controlled to be within a specific range (0 mm to 5 mm by Byreck method). This parameter optimization ensures the sheet feels dry to the touch while allowing sufficient liquid passage to prevent stickiness.
2Speed
If the front-surface sheet has high liquid-permeability to allow quick liquid passage, then liquid can reach the absorber quickly, but cotton fibers retain liquid causing stickiness on the front-surface
Solution Approach 1:
Numerous front-face/back-face penetrating openings are provided in the front-surface sheet to create direct liquid passage channels. These openings enable liquid to pass through quickly while the porous structure prevents liquid from being retained by the cotton fibers on the surface.
Solution Approach 2:
The front-surface sheet has different properties at different locations: the skin-contacting face has controlled water absorbing capacity (0-5 mm) to feel dry, while the internal structure provides high liquid permeability for quick passage to the absorber.
3Object-affected harmful factors
If cotton fibers are used in the front-surface sheet to prevent itch and rash, then skin comfort is improved, but water repellent treatment is needed to prevent stickiness
Solution Approach 1:
The water absorbing capacity of the skin-contacting face is precisely controlled within the range of 0 mm to 5 mm by the Byreck method. This parameter optimization allows the cotton fiber sheet to maintain skin comfort while naturally limiting water absorption that would cause stickiness, reducing the need for additional water repellent treatments.
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 solution reduces water retention on the front-surface sheet, inhibits sideward urine leakage, and minimizes skin irritation by allowing easy liquid diffusion and quick absorption of urine, maintaining a dry feel and preventing stickiness.
Implementation Method 1
the front-surface sheet is formed of a spunlace nonwoven fabric 100 wt% of which is composed of cotton fibers and which is coated with a water repellent agent
Implementation Method 2
the front-surface sheet... has, at least at a portion corresponding to an excreting hole, numerous front-face/back-face penetrating openings that are longer shaped in the longitudinal direction of the absorbent article
Implementation Method 3
the absorber is composed of synthetic fibers-free pulp fibers and superabsorbent polymers
Implementation Method 4
the cotton fibers form numerous longitudinal streaks and numerous lateral streaks... the openings are formed within portions surrounded by the longitudinal streaks and the lateral streaks
Data Source
Figure 1
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Figure 4
AI summary
[Problem] To prevent backflow and, in an absorbent article that uses cotton fibers in a surface sheet, to reduce retention of water in the surface sheet to the greatest extent possible. [Solution] A medium or higher volume incontinence pad (1) that absorbs at least 20 cc of urine. A surface sheet (3), which is formed by coating a spun-lace non-woven cloth that is 100 weight% cotton fibers with a water repellent, has a plurality of openings (10) that pass from top to bottom and that are formed to be vertically long in the long direction of the incontinence pad (1) formed in at least an excretion-orifice-facing section thereof. The cotton fibers form a plurality of vertical strips (11) that extend along the long direction of the incontinence pad (1) and are formed at intervals in the width direction and a plurality of horizontal strips (12) that extend along the width direction of the incontinence pad (1), are formed at intervals in the long direction, and connect the vertical strips (11). The openings (10) are formed at sections that are surrounded by the vertical strips (11) and the horizontal strips (12). The vertical strips (11) contain a greater quantity of fiber than the horizontal strips (12) and are also formed to have a higher density.