Study On Preparation And Properties Of TDI-based Waterborne Polyurethane

Polyurethane is a class of more comprehensive performance materials. It has beenwidely used in making polyurethane coatings, adhesives and inks and other fields because ofits good mechanical properties, excellent weather resistance, flexibility and so on. In recentyears, as the increasing emphasis on environmental protection and production safety, theresearch and development of water-based polyurethane materials has become the focus ofattention.In this paper, a series of modified waterborne polyurethane WPU-M and WPU-APTESwere prepared through a acetone process using2,4-toluene diisocyanate (TDI), polytetrahydrofuran glycol (PTMG),2,2-bis (hydroxymethyl) propionic acid (DMPA), ethyleneglycol(EG), melamine(M) and (3-aminopropyl)triethoxysilane(APTES) as materials, andtriethylamine (TEA) as the neutralizing agent.The optimum conditions for waterborne polyurethane emulsion were determined bycomparing its appearance, average particle diameter and centrifugal stability. The effects ofNCO/OH mole ratio, DMPA content and modifiers content on the properties of modifiedwaterborne polyurethane emulsion and its films were studied. And the properties of modifiedwaterborne polyurethane emulsion and its films were characterized by viscositymeasurements, particle size analyzer, surface water contact angle and mechanical propertiestest.Experimental results show that the water resistance and mechanical properties ofWPU-M films were improved using melamine as a crosslinking agent. The water absorptionof the films decreased and the hardness and tensile strength increased with the increase of themelamine content. The average particle size of WPU-M emulsion increased and stabilitydecreased after modified, but it was not obvious at viscosity. Under the optimal conditions,the water absorption of WPU-M was5.23%, the hardness was82HA, tensile strength was43.05MPa and elongation at break was488.9%. Because of the low surface energy of silicone,the water resistance of WPU-APTES films was improved using APTES as a modifier. And the mechanical properties were improved when the APTES content was more than7.0%. Underthe optimal conditions, the water absorption of WPU-APTES was4.18%, the surface watercontact angle was79°, tensile strength was42.19MPa and elongation at break was166.9%.