Pages 441–443
Abstract
Research summary supplied by the authors
The leather industry produces large volumes of solid wastes, particularly fleshing and trimming residues, which are rich in collagenous proteins but often disposed of without value recovery. This study presents a sustainable approach to transforming these protein rich wastes into functional fillers for upholstery leather applications. Fleshing waste was hydrolysed under controlled thermal–alkaline conditions to extract collagen hydrolysate with a suitable molecular weight distribution for film forming and fibre binding properties. The obtained hydrolysate was refined through fat removal and pH adjustment to enhance stability and compatibility with conventional retanning systems. A protein based filler was formulated by blending the purified hydrolysate with natural polysaccharides and eco friendly crosslinkers to achieve optimal viscosity, penetration behaviour, and filling capacity. Rheological and particle size analyses confirmed the formation of a stable, uniform dispersion suitable for drum application. When applied during the retanning stage, the synthesized filler demonstrated excellent fibre plumping characteristics, improved fullness, and enhanced grain tightness, comparable to or better than commercial protein fillers used in upholstery leather manufacture. Mechanical testing of finished leathers showed improvements in softness, thickness, and tensile properties while maintaining desirable hand and flexibility. The process significantly reduces dependence on synthetic fillers and offers an environmentally responsible pathway for managing tannery solid waste. This work highlights an effective circular economy strategy that converts low value leather residues into high performance functional materials for sustainable upholstery leather production.