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The production principle of medical non-woven dressings is mainly based on non-woven technology, which directly bonds fibers into fabric through physical or chemical methods, eliminating the spinning and weaving steps required in traditional textile processes. Its core principles and process flow are as follows:

I. Fiber Raw Materials and Pretreatment

Raw Material Selection

Commonly used fibers for medical non-woven dressings include:

Synthetic fibers: Polypropylene (PP), polyester (PET), polyamide (PA), etc., which feature good chemical stability and high strength.

Natural/regenerated fibers: Viscose fibers (rayon), chitin fibers, etc., used to improve skin-friendliness or antibacterial properties.

Functional additives: Such as alginate, carbon fibers, etc., used to enhance liquid absorption, antibacterial, or adsorption performance.

Fiber Processing

Raw materials go through processes like opening and carding to form a fluffy fiber web. In some processes, different fibers need to be mixed to optimize performance (e.g., combining hydrophilicity and hydrophobicity).

II. Web Formation Technology

Based on the formation method of fiber webs, the main technologies are divided into the following types:

Dry Web Formation

Air-laid web formation: Fibers are blown onto a web-forming curtain by airflow to form a uniform fiber web, suitable for short fibers (e.g., wood pulp fibers).

Carded web formation: Fibers are mechanically carded to arrange them in a directional or random manner, applicable to synthetic fibers.

Wet Web Formation

Fibers are suspended in water, and a fiber web is formed through papermaking technology, suitable for ultra-short fibers (e.g., length < 20mm).

Direct Polymer Web Formation

Spunbond method: Molten polymer is extruded through spinnerets, stretched to form continuous filaments, and then directly laid into a web.

Melt-blown method: High-velocity hot air blows molten polymer into ultra-fine short fibers, which are randomly deposited to form a web with finer fiber diameters (on the micron scale).

III. Fiber Web Reinforcement Technology

Mechanical Reinforcement

Spunlace method: High-pressure micro-water jets are sprayed onto the fiber web to entangle the fibers (flexible reinforcement without damaging fibers), suitable for highly absorbent dressings.

Needle-punching method: Barbed needles pierce the fiber web to entangle the fibers, suitable for thick products (e.g., wound filling dressings).

Thermal Bonding Reinforcement

Hot-melt fibers or powders are added to the fiber web; after heating, they melt and cool to form point-bonded or surface-bonded structures (e.g., surgical dressings).

Chemical Bonding

Adhesives (e.g., acrylic resin) are sprayed to reinforce the fiber web, requiring subsequent drying treatment.

Self-Bonding

Filaments produced by the spunbond or melt-blown method bond to each other using residual heat (e.g., SMS composite structure: spunbond - melt-blown - spunbond).

IV. Post-Finishing and Sterilization

Functional Treatment

Hydrophilic/hydrophobic coating: Surface properties are adjusted through dipping or spraying.

Antibacterial treatment: Antibacterial agents such as silver ions and chitin are added.

Cutting and Packaging

The material is cut into dressing sizes as required; some products need independent sterile packaging (ethylene oxide sterilization with a residual amount ≤ 10μg/g).

Environmental Characteristics

PP-based (polypropylene-based) non-woven fabrics are biodegradable (90 days outdoors, 8 years indoors), meeting medical environmental protection requirements.

V. Examples of Special Processes for Medical Dressings

SMS Composite Process

It combines the strength of the spunbond layer and the filtration performance of the melt-blown layer, and is used for high-protection dressings (e.g., surgical isolation layers).

Spunlace-Chitin Composite Process

Chitin fibers are added to the spunlace-entangled fiber web, providing both softness and antibacterial properties.

VI. Summary

The core of the production principle of medical non-woven dressings lies in directional/random fiber web formation and multi-method bonding technology. Through the combination of different processes, medical requirements such as breathability, liquid absorption, and bacteria resistance are achieved. Future trends include the application of biodegradable materials (e.g., PLA) and intelligent dressings (nanoscale antibacterial).