Preparation method of silicone modified waterborne polyurethane
Global Silicone Network News:


      Silicone-modified water-based polyurethane also has two methods: blending modification and copolymerization modification. Blending can be achieved by physical blending of aqueous polyurethane emulsions and polysiloxane emulsions. Polyurethane can improve the oil resistance of polysiloxane emulsion, while polysiloxane emulsion can improve the water resistance and solvent resistance of water-based polyurethane. However, due to the presence of emulsifiers, the blending modification has a negative impact on the performance of the final film. The blending modification is only a simple mechanical mixing, no chemical bond is formed, and the silicone oil is easy to migrate, resulting in a short silicon-like aging effect. Copolymerization modification is the most commonly used method for organosilicon modification of waterborne polyurethane, through polysiloxane oligomers with reactive functional groups at both ends (such as hydroxyl silicone oil, amino silicone oil, amino or alkoxy terminated silane coupling agent) etc.) and polyisocyanates are gradually added and polymerized to obtain block copolymers.


      The preparation methods of silicone copolymer modified waterborne polyurethane mainly include two different methods: synthesis and chain extension. The synthesis method is to introduce hydroxyl silicone oil or amino silicone oil into the polyurethane segment during the synthesis of the prepolymer. Hydroxy silicone oil has moderate reactivity, stable reaction in the synthesis process, and better control than amino silicone oil. The chain extension method refers to the introduction of amino silicone oil for chain extension in the process of prepolymer emulsification.