# Sanitary Napkins Raw Material Composition and Properties

Sanitary napkins are essential personal hygiene products used by women during menstruation. Understanding the raw materials used in their production is crucial for ensuring comfort, safety, and effectiveness. This article delves into the composition and properties of the primary materials used in sanitary napkins.

## 1. Absorbent Core

The absorbent core is the most critical component of a sanitary napkin. It is responsible for absorbing and retaining menstrual fluid. The core is typically made from a blend of the following materials:

– **Wood Pulp**: Wood pulp is a natural, biodegradable material that provides excellent absorbency. It is often used in combination with other materials to enhance its performance.
– **Superabsorbent Polymers (SAP)**: SAPs are synthetic materials that can absorb and retain large amounts of liquid relative to their own mass. They are highly effective in maintaining dryness and preventing leakage.

## 2. Top Sheet

The top sheet is the layer that comes into direct contact with the skin. It must be soft, comfortable, and allow for quick liquid transfer to the absorbent core. Common materials used for the top sheet include:

– **Nonwoven Fabrics**: These are made from synthetic fibers such as polypropylene or polyester. They are lightweight, breathable, and provide a smooth surface for comfort.
– **Perforated Films**: These are thin plastic films with tiny holes that allow liquid 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 and provide a barrier against moisture. Materials used for the back sheet include:

– **Polyethylene Films**: These are waterproof and provide an effective barrier against leaks. They are also flexible and durable.
– **Breathable Films**: These films allow air to pass through while still preventing liquid leakage, enhancing comfort by reducing moisture buildup.

## 4. Adhesive

Adhesives are used to secure the sanitary napkin in place. They must be strong enough to hold the napkin in position but gentle enough to avoid skin irritation. Common types of adhesives include:

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

## 5. Release Paper

Release paper is used to protect the adhesive before use. It is typically made from silicone-coated paper or film, which allows it to be easily peeled away without leaving residue.

## Properties of Sanitary Napkin Materials

The materials used in sanitary napkins must possess several key properties to ensure their effectiveness and safety:

– **Absorbency**: High absorbency is crucial for managing menstrual flow effectively.
– **Softness**: The materials must be soft and gentle on the skin to prevent irritation.
– **Breathability**: Good breathability helps maintain skin health by reducing moisture buildup.
– **Hypoallergenic**: Materials should be hypoallergenic to minimize the risk of allergic reactions.
– **Biodegradability**: Increasingly, there is a demand for biodegradable materials to reduce environmental impact.

In conclusion, the composition and properties of the raw materials used in sanitary napkins play a vital role in their performance and user comfort. By understanding these materials, manufacturers can continue to innovate and improve the quality of these essential hygiene products.