# 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.

## Core Absorbent Material

The core of a sanitary napkin is typically made from a blend of wood pulp and superabsorbent polymers (SAP). Wood pulp provides the necessary bulk and absorbency, while SAP enhances the napkin’s ability to retain liquid. The combination of these materials ensures that the napkin can effectively manage menstrual flow without leakage.

### Wood Pulp

Wood pulp is a natural fiber derived from trees. It is highly absorbent and biodegradable, making it an environmentally friendly choice. The pulp is processed to remove impurities and then fluffed to increase its absorbency. In sanitary napkins, wood pulp is often used in its bleached form to ensure hygiene and aesthetic appeal.

### Superabsorbent Polymers (SAP)

Superabsorbent polymers are synthetic materials that can absorb and retain large amounts of liquid relative to their own mass. SAP is typically used in the form of small granules or powder, which are evenly distributed within the core of the napkin. These polymers swell upon contact with liquid, forming a gel-like substance that locks in moisture and prevents leakage.

## Top Sheet Material

The top sheet is the layer of the sanitary napkin that comes into direct contact with the skin. It is designed to be soft, comfortable, and quick-drying. The most common materials used for the top sheet are non-woven fabrics and perforated films.

### Non-Woven Fabrics

Non-woven fabrics are made from synthetic fibers such as polypropylene or polyester. These fabrics are lightweight, breathable, and soft to the touch. They are also highly durable and resistant to tearing, making them ideal for use in sanitary napkins. Non-woven fabrics can be treated with various finishes to enhance their softness and moisture-wicking properties.

### Perforated Films

Perforated films are thin plastic sheets with tiny holes that allow liquid to pass through while keeping the surface dry. These films are often used in combination with non-woven fabrics to create a top sheet that is both comfortable and effective at managing menstrual flow. Perforated films are also easy to clean and maintain, adding to the overall convenience of the product.

## Back Sheet Material

The back sheet is the outermost layer of the sanitary napkin, designed to prevent leakage and protect clothing. It is typically made from a waterproof material such as polyethylene or polypropylene film.

### Polyethylene Film

Polyethylene film is a lightweight, flexible plastic material that is highly resistant to water and other liquids. It is commonly used as the back sheet in sanitary napkins due to its excellent barrier properties. Polyethylene film is also easy to print on, allowing manufacturers to add branding and design elements to the product.

### Polypropylene Film

Polypropylene film is another popular choice for back sheets. It is similar to polyethylene in terms of its waterproof properties but offers additional benefits such as higher tensile strength and better resistance to heat. Polypropylene film is also more environmentally friendly, as it can be recycled more easily than polyethylene.

## Adhesive and Release Paper

To ensure that the sanitary napkin stays in place during use, an adhesive is applied to the back sheet. The adhesive is typically a pressure-sensitive type that adheres to underwear without causing irritation. A release paper is used to cover the adhesive until the napkin is ready to be used.

### Pressure-Sensitive Adhesive

Pressure-sensitive adhesives are designed to stick to surfaces when pressure is applied. They are commonly used in sanitary napkins because they provide a strong yet gentle hold. These adhesives are also formulated to be hypoallergenic, reducing the risk of skin irritation.

### Release Paper

Release paper is a coated paper that