spunlaid

Spunlaid describes a nonwoven fabric process where filament fibres are extruded from spinnerets, cooled, and immediately directed onto a moving conveyor belt or collection surface by air streams or mechanical deflectors, without first being wound into yarn. The fibres land randomly and bond together through heat, pressure, or chemical adhesive to form a cohesive sheet. This differs from traditional textile manufacture, where yarn spinning and fabric weaving or knitting are separate stages.

The process captures filament in its nascent state. Typical spunlaid equipment runs at 200 to 600 metres per minute depending on fibre denier and web weight targets. Common fibre materials include polypropylene, polyester, and polyethylene; fibre diameters range from 1 to 10 microns. The random orientation of asplaid webs gives them different properties in machine and cross-machine directions, unlike woven cloth.

Where the name comes from

The term combines "spun" (the extrusion and attenuation of filament) and "laid" (the placement onto a web forming surface). It emerged in the 1950s as equipment manufacturers refined methods to bypass intermediate yarn stages. The distinction matters: a spunbond web has fibres bonded at intersection points; a spunlaid web may refer more broadly to any direct fibre-to-web process, sometimes including meltblown layers.

Spunlaid nonwovens cost less per unit mass than spun yarn fabrics because they eliminate yarn winding and twisting machinery, reducing handling and energy use. Typical end uses include geotextiles, filtration media, medical apparel, and wipe substrates. Tensile strength depends on fibre crimp, basis weight (grams per square metre), and bond density. A spunlaid geotextile at 200 gsm might show 60 to 100 kN/m tensile strength in machine direction.

The chief limitation is consistency. Deflector positioning, air velocity, and conveyor speed fluctuations create thick and thin spots in the web. Uneven bonding during heat treatment causes stiff patches or delamination. Quality control requires continuous basis weight monitoring and pore size testing. Spunlaid stock also has lower abrasion resistance than needle-punched nonwovens because fibres are not mechanically interlocked.