Modification of polyurethane finishing agent using collagen hydrolysate from chrome shavings

Finishing with traditional polyurethane finishing agents often dramatically decreases the permeability of finished leathers. Continuing attempts have been made in recent years to develop aqueous polyurethanes (PU) finishing agents with better overall balance of properties while retaining characteristic high durability. Research in our industry has also included many studies to optimize use of the collagen available from chrome shavings. Collagen hydrolysate may contain a number of hydrophilic groups such as carboxylic, hydroxylic, amino, imino, and amide. The reactions between these collagen hydrolysate active groups and the urethane reactive groups (-NCO) resulted in the synthesis of new polyurethane finishing agents which offered increased permeability. The optimum collagen hydrolysate modifying condition for this polyurethane finishing agent was found to be: DMPA, 5% of the monomers by weight, reaction temperature of 80°C and reaction time of 2.5 hours. When the collagen hydrolysate is in the range of 0.6-0.8% of IPDI by weight, a range of good properties is achievable. For exampje, when collagen hydrolysate is 0.6% of IPDI by weight, the modified polyurethane finishing agent has high strength appropriate for use in basecoat or topcoat finishes. When the collagen hydrolysate is 0.8% of IPDI by weight, the modified polyurethane finishing agent has good elongation at break and extensibility, indicating a potential application in leather sealing finishes.