# Sanitary Napkins Raw Material Composition and Properties

Sanitary napkins, commonly known as sanitary pads, are essential feminine hygiene products designed to absorb menstrual flow. The effectiveness and comfort of these products largely depend on the raw materials used in their composition. Understanding the materials and their properties can help in making informed choices and appreciating the technology behind these everyday items.

## Core Absorbent Material

The core of a sanitary napkin is primarily made from absorbent materials that can quickly soak up and retain menstrual fluid. The most commonly used materials include:

– Wood Pulp: This is a natural fiber derived from wood. It is highly absorbent and forms the bulk of the core in many sanitary napkins.
– Super Absorbent Polymer (SAP): SAP is a synthetic material that can absorb and retain large amounts of liquid relative to its own mass. It is often used in conjunction with wood pulp to enhance the absorbency of the napkin.
– Cotton: Some premium sanitary napkins use cotton as the core material. Cotton is soft, breathable, and hypoallergenic, making it suitable for sensitive skin.

## Top Sheet Material

The top sheet is the layer that comes in direct contact with the skin. It needs to be soft, comfortable, and quick-drying. Common materials used for the top sheet include:

– Non-Woven Fabric: This is a synthetic fabric made from fibers bonded together by chemical, mechanical, or thermal processes. It is soft, breathable, and allows for quick absorption of menstrual fluid.
– Perforated Film: Some sanitary napkins use a perforated plastic film as the top sheet. This material is less breathable but provides a smooth surface that prevents leakage.

## Back Sheet Material

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 Film: This is a thin, flexible plastic film that is waterproof and prevents leakage. It is commonly used in disposable sanitary napkins.
– Breathable Microporous Film: Some high-end sanitary napkins use a breathable microporous film that allows air to pass through while still preventing liquid leakage.

## Adhesive and Release Paper

To keep the sanitary napkin in place, an adhesive is applied to the back sheet. The adhesive is usually a pressure-sensitive adhesive that sticks to the underwear without leaving residue. The adhesive is covered with a release paper that is removed before use.

## Additional Components

Some sanitary napkins may include additional components for enhanced comfort and functionality:

– Fragrance: Some products add a light fragrance to mask menstrual odor. However, fragrances can cause irritation for some users.
– Wings: Wings are flaps on the sides of the napkin that fold over the edges of the underwear to provide extra protection against leakage.
– Embossing: Embossing on the top sheet can help distribute menstrual fluid more evenly and prevent bunching.

## Properties of Sanitary Napkin Materials

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

– Absorbency: The ability to quickly absorb and retain menstrual fluid is crucial. SAP and wood pulp are highly absorbent materials.
– Softness: The top sheet needs to be soft to prevent irritation and provide comfort. Non-woven fabrics and cotton are preferred for their softness.
– Breathability: Breathable materials like non-woven fabrics and microporous films allow air circulation, reducing the risk of skin irritation and discomfort.
– Leakage Protection: The back sheet must be impermeable to liquids to prevent leakage. Polyethylene and microporous films are effective in this regard.
– Hypoallergenic: Materials like cotton are hypoallergenic and suitable for sensitive skin, reducing the risk of allergic reactions.

In conclusion, the composition of sanitary napkins involves a combination of materials each selected for their specific properties to ensure comfort, absorbency, and leakage protection. Understanding these materials