Bicomponent and Microfibre Synthetic Fibre Technology

Bicomponent fibre technology combines two polymer components within a single filament through specially designed spinneret geometry — enabling functionalities impossible in single-component fibres including self-crimping, microfibre splitting, wicking channels, flame resistance, and controlled biodegradation. Bicomponent configurations: side-by-side (S/S — two polymers side by side, differential shrinkage creates 3D helical crimp); eccentric core-sheath (E/C/S — off-centre core creates asymmetric shrinkage and self-crimping); concentric core-sheath (C/C/S — inner core and outer sheath with different properties — e.g., PA6 core for strength + PP sheath for moisture wicking); segmented pie (S/P — pie-wedge segments 8–16, PET/PA6 alternating segments, split by hydroentanglement or solvent treatment to 0.01–0.10 dtex microfibres); islands-in-the-sea (I/S or sea-island, 16–37 islands of target polymer in dissolvable sea polymer matrix, sea dissolved by NaOH → ultra-fine island microfibres 0.001–0.01 dtex). Microfibre definition: filament linear density <1 dtex per filament (some definitions <0.5 dtex, ultra-microfibre <0.1 dtex) — commercially produced as conventional fine single-component (PET FDY 0.5–0.8 dtex, limits below 0.3 dtex by single-component melt spinning) or bicomponent segmented pie / sea-island for ultra-microfibre. Microfibre properties: increased surface area per unit mass (0.1 dtex fibre has 10× surface area of 1.0 dtex fibre of same polymer) → superior softness (bending stiffness ∝ d⁴, 0.1 dtex fibre 10,000× softer than 1.0 dtex equivalent), improved moisture wicking (capillary suction in microfibre bundles), higher absorbency in nonwovens, finer filtration. Market: bicomponent fibre 6 million tonnes (2023, estimated — included in PET/PA6 totals), microfibre suede (Alcantara, Toray Ultrasuede) $2 billion market, microfibre cleaning cloth $1.5 billion, microfibre sportswear $8 billion segment.