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- Last UpdatedDecember 27, 2025
1. The Basic Waterproof Mechanism: Impermeable Molecular Structure
PE molecules are tightly packed in a non-porous, hydrophobic (water-repelling) matrix. Liquid molecules (e.g., urine, menstrual flow) are too large to pass through the gaps between PE chains, creating an impermeable barrier that traps liquid inside the product.
Unlike porous materials (e.g., nonwoven fabric), PE does not absorb moisture—so even when saturated, it won’t "bleed" liquid through to clothing.
2. Integration with Absorbent Components: Trapping Liquid and Locking It In
The absorbent core (made of fluff pulp + superabsorbent polymers, SAP) first draws liquid away from the user’s skin via capillary action.
Once the core absorbs and locks liquid (SAP swells to trap moisture), the PE film acts as a secondary barrier: it blocks any liquid that might seep through the core (e.g., during heavy use or movement) from escaping the product.
3. Design Enhancements: Targeting High-Leak Zones
Elasticized PE wings (in pads/diapers): PE film is combined with elastic fibers to create snug-fitting wings that wrap around underwear/diaper edges. This seals gaps where liquid might leak during movement (e.g., leg openings in diapers).
Contoured PE backsheets: For diapers, PE film is shaped into an arc (matching the body’s curve) to concentrate liquid toward the absorbent core, reducing the chance of side leaks.
Multi-layer PE laminates: Some high-end products use 2–3 layers of PE (or PE + nonwoven) to add extra durability—critical for overnight-use products that hold more liquid.
4. Why PE Film Outperforms Alternatives for Leak Protection
It’s consistently waterproof (unlike some biodegradable films, which may degrade when exposed to liquid over time).
It’s flexible enough to maintain a seal during movement (stiffer materials can crack or shift, creating leak gaps).
It’s cost-effective for mass production—critical for making hygiene products accessible globally.