Study On Waterborne Polyurethanes For Fabric Coating

In the textile industry, polyurethane has shown good performance in printing, dyeing auxiliaries and finishing agent such as anti-wrinkle, waterproof and oilproof, antiflaming and breathability. It’s the coated fabric finishing that the textile is coated with thin film to make the fabric has a particular function or style. Waterborne polyurethane has already became a development direction in fabric dyeing processing as a formaldehyde-free textile finishing agent. It has a wide application as leather finishing agent and fabric coating adhisives.Epoxy soybean oil has good stability and thermal stability of light, oil resistance and excellent water resistance. It offers good weather resistance and mechanical strength and electrical property to the products. Furthermore, as a harmless and enviromental friendly material, epoxy soybean oil has got international recognition in food packing. Products modified by epoxy soybean oil shows good aboundance ratio, together with its own many good performance, so we synthesized epoxy soybean oil modified waterborne polyurethane to combine the advantage of them. The compound we synthesized can be widely used in indoor and outdoor even severe weather conditions.In order to expand the application of waterborne polyurethane and reduce the cost, we adopted two kind of aliphatic isocyanate as hard segments.1. Preparation, characterization and performance testing of epoxy soybean oil modified waterborne polyurethane.Using diethanol amine to open loops in epoxy soybean oil, and then introduce them into polyurethane to synthesize a series of epoxy soybean oil modified waterborne polyurethane. FT-IR showed that epoxy soybean oil was brought in polyurethane with chemical bond. The results as follows:First, by modified with epoxy soybean oil, the emulsion particle size increase, storage stability decrease. Second, water asoption decreased, tensile strength increased and elongation at break down decreased. Third, the heat resistance of the modified resein increased. As a result, the introduction of grease and system of crosslinking degree is of great importance to increase the performance of the polymer.2. Preparation, characterization and performance testing of hybrid isocyanate waterborne polyurethane.A series of waterborne polyurethane were synthesized using polyether glycol, different types of isocyanate, through changing hybrid isocyanate types as well as the mixing ratio of isocyanate.The results show that:First, the average particle size of hybrid isocyanate water-borne polyurethane emulsion was less then20nm, and slightly increase with the increasing of hard segment. Second, the film is soft and has a larger elongation at break, all were above600%, and decreased with the increasing of molecular weight and volume of hard segment. But the corresponding tensile strength were improved. Third, when HMDI increased in the proportion, the film thermal decomposition temperature increased because of the rigid structure increased.3. Preparation, characterization and performance testing of waterborne polyurethane coating adhesive.This part adopts the waterborne polyurethane emulsion synthesized in the second chapter and the third chapter, and joined several right amount of additives to make water polyurethane adhesive, and coated it on fabric. Test results show that:First, coating amount increased, moisture permeability evidently decreased; baking temperature and time have less influence on moisture permeability, no destroy the film as a condition. Second, hydrostatic pressure resistance value increased obviously along with the increasing of coating amount, baking temperature and time. When they reach a certain temperature, extend the baking time, fabric of hydrostatic pressure change little.Third, Contact Angle displays that isocyanate type and mixed ratio have littile infuence on the hydrophobic property. The hydrophobic property of epoxy soybean oil modified waterborne polyurethane coating adhesive changed obviously. Contact angle and hydrophobic property enhanced with the increasing of epoxy soybean oil and its open loops proportion.In conclusion, the synthesized epoxy soybean oil modified polyurethane resin and hybrid isocyanate waterborne polyurethane both have excellent performance and the simple processing. It provides a better choice in coating adhesives while seeking for base resin.