Modification Of Polyurethane Finishing Agents With Collagen

Aqueous polyurethane (PU) is a two-phase colloid system, in which water is the dispersible medium. Compared with the solvent type polyurethane, the aqueous polyurethane has such advantages as innocuity, not easy to be burnt, and environment friendly. Protein finishing agents includes casein, gelatin and their modified products. They are green and may be obtained easily. The development of aqueous PU and protein finishing agents has been motivated primarily by environmental considerations, in order to reduce solvent emissions into the atmosphere. In this paper, aqueous PU finishing agents are prepared with toluene 2, 4 -diisocyanate (TDI), polypropylene glycol (PPG) , 1, 4-butandiol(BDO), tartaric acid (TAC), triethanolamine (TEA) and glycerol as raw materials. Collagen hydrolysate with different relative molecular weight is employed in different stages of polymerization to gain different modified products. Chemical reactions between polyurethane and collagen hydrolysate are proved by FTIR spectroscopy. The properties of the emulsions are studied. The thermal properties of the samples are completed by differential scanning calorimetry (DSC). The results indicate that the general properties of the modified products are excellent, and they are suitable for being used as finishing agents in tanneries.Such factors that may affect the properties of the modified products as pre-polymerization temperature, -NCO/-OH mole ratio, the relative molecular weight of polypropylene glycol (PPG), the dosage of 1, 4-butanediol(BDO), tartaric acid (TAC), triethanolamine (TEA), and collagen hydrolysate are studied. The results show that, with the increase of prepolymerization temperature, the prepolymerization is speeded, and the temperature of 60°C is the appropriate prepolymerization temperature. With the the increase of the -NCO/-OH mole ratio, the viscosity of the emulsion decreases, the elongation at break of the PU films decreases, the water-absorption of the PU films decreases, while the tensile strength and hardness of the PU films increase. With the relative molecular weight of PPG increases, the tensile strength, the hardness and the water absorption of the PU films decrease, while...