Preparation Of Cationic Polyethylene (PE) Wax Emulsion And Effects On Properties Of Leather Coatings In Finishing

To study the application of polyethylene wax (PE) on leather finishing, the polyethylene wax was oxidized with O2and groups like-COOH,-CO-were added into its structure to buildup the properties of hydrophility and emulsifiability. And the modified wax was prepared by esterifiying oxidized polyethylene (OPE) wax with triethanolamine(TEA). Then the modified wax was emulsified with a kind of compound cationic surface-active agents to prepare a homogeneous and steady cationic polyethylene wax emulsion. And then some films were made by mix the cationic polyethylene wax emulsion with cationic resin film-forming agents like polyacrylate acid resin and polyurethane emulsion, and the properties of the films were analyzed and tested. At last, the cationic modified polyethylene wax emulsion was used in the leather finishing to study its application property, and the application experiments show that cationic PE emulsion is a kind of leather finishing additive with good performances.In the process of oxidizing the PE wax, the acid value was determined to reflect the degree of oxidation. And the factors that affect the degree of oxidation, such as temperature, air flux, amount of catalyst, and the oxidation time were analyzed using the method of single factor analysis. And the conclusions show that oxidizing PE for 6 hours at 160～170℃,800-1000L L/h of air flux and 1.0%～1.5% of catalyst amount based on mass of polyethylene wax, the preparation with 20.00～25.00 mg KOH/g acid value can be prepared, and IR was used to analyze the molecule structure of the preparation.Then the OPE wax was esterified with triethanolamine, and the amount of water that generated in the reaction and the amount of residual triethanolamine were determined to reflect the degree of esterification. The results indicate that esterification rate can reach to 89%.The oxidized polyethylene wax (OPE) modified with TEA was emulsified to steady cationic emulsion with the methods of phase conversion and compounding emulsifiers. Experiment results show that both the emulsibility and emulsion stability of modified OPE were improved obviously. And factors affected the properties of wax emulsion were sorts of emulsifiers, amount of emulsifiers, emulsifying temperature and shearing speed. The optimal results are: combination emulsifiers of OS-15 and 1631, which amount respectively are 15% and 5% based on the mass of OPE wax; emulsifying temperature at 90～95℃, stirring rate at 800～1000r/min, continuously stirring for 40-60min.And a pale yellow and partially transparent emulsion was prepared, with pH at 4.0-5.0, and the average diameter of particles at 0.187μm.And then the film of the cationic modified polyethylene wax emulsion mixed with common cationic film forming agents was made, and the properties as mechanical properties, resistance to solvent were tested. The results show that the cationic modified polyethylene wax emulsion can improve the mechanical properties of the film formed with polyacrylate acid resin and polyurethane emulsion as strengthen the tensile strength and tear strength, and reinforce the resistance to water, sweat and acetone as well, when used together at a prorate 20% based on the film forming agents. But the amount of the cationic modified polyethylene wax emulsion should not be in excess, to prevent the film from being too hard and brittle and producing bad impact on the feel and the subsequent process.And lastly the cationic modified polyethylene wax emulsion was used in the leather finishing, using the cationic finishing system, compared with 252-FL wax emulsion. The experiment results point that that the finishing effects of home-made wax emulsions overall are satisfying, and the property of mixture with other finishing agents was fine, and the self-made wax emulsion coating have stronger acerbity sense and feels pump, and it was suitable for Nappa style finishing. Furthermore, the cationic modified polyethylene wax emulsion has good properties on filling and preventing coatings from stuck when ironing. In addition, its coating has high gloss, which can be used for polishing.