Waterproof vs. Breathable Backsheet: Which Is the Right Choice for Different Products?

The backsheet is the outer layer of a diaper or sanitary napkin. Its primary function is to act as a liquid barrier, preventing absorbed fluid from leaking out and soiling clothing or bedding. Beyond this fundamental requirement, backsheets are divided into two main categories: waterproof (non-breathable) and breathable (microporous). Each type involves a trade-off between liquid barrier performance and vapor permeability, and the choice between them depends on the product's intended use, wear duration, and target consumer expectations.

Waterproof Backsheet: Absolute Barrier

A waterproof backsheet is typically a solid polyethylene (PE) or polypropylene (PP) film with no intentional pores. It provides an impermeable barrier against liquids, ensuring zero leakage under all conditions. However, this same impermeability also blocks water vapor, trapping heat and moisture inside the product. In extended wear, this trapped moisture increases the risk of skin irritation and diaper rash.

• Advantages: Absolute liquid barrier; no leakage risk; lower cost; simpler manufacturing.

• Disadvantages: No vapor permeability; increased heat and moisture buildup; higher risk of skin issues in extended wear.