Hydrophobic Cellulosic Backsheet for Absorbent Articles
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Solution Overview
Problem
Current disposable absorbent products lack a breathable backsheet material that balances air permeability with sufficient liquid barrier performance, leading to discomfort and inefficiency in maintaining skin transpiration and preventing leakage.
Innovation Solution
Development of a multi-layered laminate comprising a hydrophobically treated cellulosic fiber layer and a synthetic nonwoven support layer, which provides high air permeability and effective liquid barrier performance by optimizing pore size distribution and mechanical integrity, allowing for reduced basis weight while maintaining structural support and leakage protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a nonwoven backsheet with small pores is used to improve liquid barrier performance, then liquid barrier performance is improved, but air permeability decreases
Solution Approach 1:
The patent applies parameter changes by treating cellulosic fibers with hydrophobic sizing agents, which fundamentally alters the surface energy and wetting properties of the fibers. This chemical modification allows the same pore structure to simultaneously provide liquid barrier performance (by preventing capillary wicking) and maintain air permeability (by allowing vapor diffusion through hydrophobic pathways). The contact angle parameter is specifically modified to be greater than 90 degrees, creating a hydrophobic surface that repels liquid while permitting breathable vapor transmission.
Solution Approach 2:
The patent creates a composite material system by combining hydrophobically treated cellulosic fibers with synthetic hydrophobic fibers (such as polypropylene or polyester). This composite structure leverages the complementary properties of each fiber type: the treated cellulosic fibers provide a natural pore structure with improved liquid resistance, while the synthetic fibers reinforce the hydrophobic effect and structural integrity. The synergistic combination achieves both high liquid barrier performance and maintained air permeability that neither material could achieve alone.
2Ease of operation
If the basis weight of the nonwoven is reduced to improve comfort and breathability, then air permeability is improved, but mechanical strength and structural integrity deteriorate
Solution Approach 1:
The patent applies parameter changes by modifying the surface energy characteristics of cellulosic fibers through hydrophobic sizing treatment. This chemical modification fundamentally changes the interaction between liquid and fiber surfaces, allowing the material to achieve liquid barrier performance without requiring increased basis weight. The treated lighter-weight nonwoven maintains mechanical adequacy while providing both breathability and liquid resistance that would otherwise require a heavier construction.
Solution Approach 2:
The patent employs disposable cellulosic fibers (such as wood pulp) that are inherently biodegradable and cost-effective. By treating these short-lived, inexpensive fibers with hydrophobic sizing, the patent creates a single-use backsheet that provides adequate mechanical strength for its intended lifecycle while maintaining light weight for comfort. The disposable nature allows optimization for breathability without compromising on mechanical strength requirements.
3Reliability
If hydrophobic sizing is applied to cellulosic fibers to improve liquid barrier performance, then liquid barrier performance is improved, but hydrophilic properties are lost
Solution Approach 1:
The patent applies parameter changes by systematically modifying the surface energy of cellulosic fibers through controlled hydrophobic sizing treatment. This chemical modification transforms the surface characteristics from hydrophilic to hydrophobic, achieving liquid barrier performance through increased contact angle. The treatment parameters (sizing agent concentration, application method, drying conditions) are optimized to achieve the desired hydrophobic effect while preserving the bulk material's ability to provide structural support and breathability.
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 laminate achieves enhanced breathability and liquid barrier performance, comparable to polyester/cotton fabrics, with improved tensile strength and reduced pinhole formation, making it suitable for use in absorbent products like diapers and surgical gowns.
Implementation Method 1
a cellulosic fiber barrier layer having a hydrophobic sizing, the barrier layer having an air permeability of more than 0.5 ft3/min-ft2
Data Source
Figure 1A~1B
Figure 1C~2
Figure 3
AI summary
The present disclosure includes cellulosic fiber barrier layer having a hydrophobic sizing to cause the barrier layer to exhibit hydrophobic properties. For example, the present cellulosic fiber barrier layers can be configured to have a high hydrostatic head (e.g., more than 200 mm H20) while retaining a high air permeability (e.g., 0.5 ft3/min-ft2). The present disclosure also includes laminates (e.g., a breathable backsheet assembly) including one of the present cellulosic fiber barrier layers and a nonwoven support layer positioned beneath and coupled (e.g., bonded) to the barrier layer, such that the laminate is configured to exhibit desirable liquid-barrier performance (e.g., pinhole-free performance at 400 mm H20 for 10 minutes, and/or the like). The present disclosure also includes disposable absorbent garments including at least one of the present cellulosic fiber layers and laminates (e.g., including one of the present laminates as a backsheet for the disposable absorbent garment).