# 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 combination of the following materials:

– **Wood Pulp**: This is the most common material used in the absorbent core. It is highly absorbent and helps in retaining fluid.
– **Superabsorbent Polymers (SAP)**: These are synthetic materials that can absorb and retain large amounts of liquid relative to their own mass. SAPs enhance the absorbency of the napkin.

## 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. Common materials used for the top sheet include:

– **Nonwoven Fabrics**: These are made from synthetic fibers like polypropylene or polyester. They are soft, breathable, and allow for quick fluid transfer to the absorbent core.
– **Perforated Films**: These are thin plastic films with tiny holes that allow fluid to pass through while keeping the surface dry.

## 3. Back Sheet

The back sheet is the outermost layer of the sanitary napkin, designed to prevent leakage. It is usually made from:

– **Polyethylene Film**: This is a waterproof material that prevents fluid from leaking through the back of the napkin.
– **Breathable Films**: These are microporous films that allow air to pass through while still providing a barrier against liquid.

## 4. Adhesive

Adhesives are used to keep the sanitary napkin in place. They are applied to the back sheet and are designed to be strong enough to hold the napkin securely but gentle enough to be removed without causing discomfort. Common types of adhesives include:

– **Hot Melt Adhesives**: These are thermoplastic adhesives that are applied in a molten state and solidify upon cooling.
– **Pressure-Sensitive Adhesives**: These adhesives form a bond when pressure is applied, making them easy to use.

## 5. Release Paper

Release paper is used to cover the adhesive before the napkin is used. It is typically made from:

– **Silicone-Coated Paper**: This type of paper is treated with silicone to prevent the adhesive from sticking to it, allowing for easy removal.

## Properties of Sanitary Napkin Materials

The materials used in sanitary napkins are chosen for their specific properties, which include:

– **Absorbency**: The ability to absorb and retain fluid is crucial for the effectiveness of a sanitary napkin.
– **Softness**: The top sheet must be soft to ensure comfort during use.
– **Breathability**: Materials should allow air to circulate to prevent irritation and discomfort.
– **Leakage Protection**: The back sheet must be impermeable to prevent leaks.
– **Adhesion**: The adhesive must be strong enough to keep the napkin in place but easy to remove.

In conclusion, the composition and properties of the raw materials used in sanitary napkins are carefully selected to ensure comfort, hygiene, and effectiveness. Understanding these materials can help consumers make informed choices and manufacturers improve their products.