# Sanitary Napkins Raw Material Composition and Properties

Sanitary napkins are essential personal care products designed to provide comfort and hygiene during menstruation. Understanding the raw materials used in their production is crucial for both manufacturers and consumers. This article delves into the composition and properties of the primary materials used in sanitary napkins.

## 1. Absorbent Core

The absorbent core is the heart of a sanitary napkin, responsible for absorbing menstrual fluid. It is typically made from a blend of wood pulp and superabsorbent polymers (SAP).

### Wood Pulp

Wood pulp is a natural material derived from trees. It is highly absorbent and provides the bulk of the absorbent core. The pulp is processed to remove impurities and then fluffed to increase its absorbency.

### Superabsorbent Polymers (SAP)

SAPs are synthetic materials that can absorb and retain large amounts of liquid relative to their own mass. They are often used in conjunction with wood pulp to enhance the absorbency of the core. SAPs are typically made from polyacrylate compounds.

## 2. Top Sheet

The top sheet is the layer that comes into direct contact with the skin. It is designed to be soft, comfortable, and quick-drying.

### Nonwoven Fabric

Nonwoven fabrics are commonly used for the top sheet. These fabrics are made from synthetic fibers such as polypropylene or polyester, which are bonded together through mechanical, thermal, or chemical processes. Nonwoven fabrics are chosen for their softness, breathability, and ability to wick moisture away from the skin.

## 3. Back Sheet

The back sheet is the outermost layer of the sanitary napkin, designed to prevent leakage and provide a barrier against external moisture.

### Polyethylene Film

Polyethylene film is a common material used for the back sheet. It is a lightweight, flexible, and waterproof plastic that effectively prevents menstrual fluid from leaking through the napkin. The film is often treated to have a cloth-like texture for added comfort.

## 4. Adhesive

Adhesives are used to secure the sanitary napkin to the underwear. They must be strong enough to hold the napkin in place but gentle enough to avoid skin irritation.

### Pressure-Sensitive Adhesives

Pressure-sensitive adhesives (PSAs) are typically used for this purpose. These adhesives are designed to stick firmly to fabrics when pressure is applied, ensuring the napkin stays in place during use. PSAs are usually made from synthetic rubber or acrylic compounds.

## 5. Release Paper

Release paper is a protective layer that covers the adhesive before the napkin is used. It is peeled off to expose the adhesive when the napkin is applied to the underwear.

### Silicone-Coated Paper

Silicone-coated paper is commonly used for release paper. The silicone coating allows the paper to be easily removed from the adhesive without leaving residue or damaging the adhesive layer.

## Conclusion

The composition of sanitary napkins involves a combination of natural and synthetic materials, each chosen for its specific properties and functionality. From the absorbent core to the top sheet and back sheet, every component plays a crucial role in ensuring the effectiveness, comfort, and hygiene of the product. Understanding these materials helps consumers make informed choices and appreciate the technology behind this essential personal care item.