News & Information

Fiber Raw Materials and Pretreatment

Medical non-woven dressings start with fiber selection. Fibers are the basic building blocks. They can be filaments or short staples. Polypropylene is a common choice. It is hydrophobic, hypoallergenic, and cost-effective. Viscose fibers are used when higher absorbency is needed. Polyester fibers provide strength for durable applications.

Specialty fibers enable advanced functions. Alginate fibers come from seaweed. They are highly biocompatible. Silver-coated fibers offer antimicrobial protection. The fibers must be clean and pure.

Pretreatment prepares the fibers. Bales of fiber are opened and separated. Different fiber types are blended together. This creates a uniform mix. The process ensures consistent performance in the final dressing.

Web Formation Technology

Web formation creates the fiber mat. This is the core structure of the non-woven. There are several methods to form the web.

Air-laid web formation uses air streams. Fibers are carried and randomly distributed on a moving belt. This makes a high-loft, soft web. It is good for absorbent wound contact layers.

Carded web formation aligns fibers in parallel. It produces a stronger, thinner material. This is often used for support layers that need strength.

Spunbond technology is a direct method. Polymer filaments are extruded, stretched, and laid down directly into a web. This creates strong, uniform fabrics. They are common in surgical drapes.

Meltblown technology makes ultra-fine fibers. It produces very fine filter media. Often, it is combined with a spunbond layer. This creates an SMS structure for effective barrier dressings.

Consolidation and Bonding

Consolidation turns the loose web into a coherent fabric. Fibers are bonded together permanently. This gives the material its integrity.

Hydroentanglement uses high-pressure water jets. The jets make the fibers tangle. This creates a very soft cloth with no chemical residue. It is ideal for sensitive wound beds.

Through-air thermal bonding uses hot air. The web passes through a heated oven. Low-melt fibers melt and bond other fibers together. This results in a bulky, soft dressing.

Needle punching is a mechanical method. Barbed needles punch into the web. This physically entangles the fibers. It is often used for thicker padding.

The bonding method affects key properties. It changes softness, strength, fluid handling, and linting.

Finishing and Converting

Finishing gives the non-woven its final functional properties. These treatments are applied after the web is bonded.

Hydrophilic finishing makes fibers absorb liquid. Surfactants are applied to hydrophobic fibers like polypropylene. This is a key feature for wound dressings.

Antimicrobial finishing helps control infection. Silver ions or PHMB are integrated into the fiber matrix. This protects the wound from microbes.

Dressings can be coated or impregnated. Hydrocolloid or hydrogel layers are laminated onto the non-woven base. This adds advanced wound healing functions.

The final step is sterilization. Methods include Ethylene Oxide (EtO) or Gamma Radiation. This ensures the dressing is safe to use and stable in its package.

Quality Control and Testing

Strict testing ensures safety and performance. A batch is a production run with consistent properties.

Physical tests check basic specs. Basis weight measures mass per unit area. Thickness is measured. Mechanical tests assess tensile strength.

Fluid handling tests are critical. They measure absorbency rate and fluid retention capacity. Moisture Vapor Transmission Rate (MVTR) is tested. This affects the wound healing environment.

Barrier performance is tested. Hydrostatic pressure tests check resistance to liquid penetration. Tests measure filtration efficiency against particles and microbes.

Biocompatibility is mandatory. Tests follow ISO 10993 standards. They ensure no skin irritation or cytotoxic effects.

Every batch must be traceable. The full production history is recorded from raw materials to the finished product.