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# 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 ensuring quality and safety. 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 fluff pulp and superabsorbent polymers (SAP).

### Fluff Pulp

Fluff pulp is a type of wood pulp that is highly absorbent and soft. It is derived from softwood trees and is processed to create a fluffy, fibrous material. The primary properties of fluff pulp include:

– High absorbency
– Soft texture
– Biodegradability

### Superabsorbent Polymers (SAP)

Superabsorbent polymers are synthetic materials that can absorb and retain large amounts of liquid relative to their own mass. They are often used in conjunction with fluff pulp to enhance the absorbency of the core. Key properties of SAP include:

– High liquid retention capacity
– Swelling upon absorption
– Non-toxicity

## 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

Nonwoven fabrics are made from synthetic fibers such as polypropylene or polyester. They are chosen for their softness, breathability, and ability to wick moisture away from the skin. Properties of nonwoven fabrics include:

– Soft and gentle on the skin
– Breathable
– Moisture-wicking

### Perforated Films

Perforated films are thin plastic sheets with tiny holes that allow liquid to pass through while keeping the surface dry. They are often used in combination with nonwoven fabrics. Properties of perforated films include:

– Quick-drying
– Smooth surface
– Durable

## 3. Back Sheet

The back sheet is the outermost layer of the sanitary napkin, designed to prevent leakage and provide a barrier against moisture. It is typically made from:

### Polyethylene Films

Polyethylene films are thin, flexible plastic sheets that are impermeable to liquids. They are commonly used for the back sheet due to their waterproof properties. Key properties include:

– Waterproof
– Flexible
– Lightweight

### Breathable Films

Breathable films are a type of polyethylene film that allows air to pass through while still preventing liquid leakage. They are designed to enhance comfort by reducing moisture buildup. Properties of breathable films include:

– Air-permeable
– Waterproof
– Comfortable

## 4. Adhesives

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

### Hot Melt Adhesives

Hot melt adhesives are thermoplastic materials that are applied in a molten state and solidify upon cooling. They are known for their strong bonding properties and flexibility. Properties include:

– Strong adhesion
– Flexible
– Fast-setting

### Pressure-Sensitive Adhesives

Pressure-sensitive adhesives are designed to form a bond when pressure is applied. They are commonly used in sanitary napkins for their ease of application and gentle removal. Properties include:

– Easy application
– Gentle removal
– Good adhesion

## Conclusion

The raw materials used in sanitary napkins are carefully selected to ensure comfort, absorbency, and leak protection. From the absorbent core to the back sheet, each component plays a vital role in the overall performance of the product. Understanding the composition and properties of these materials helps in appreciating the engineering behind this essential personal care item.