Abstract: Hybrid emulsion of castor oil polyurethane-acrylate(CPUA) was prepared by co-polymerization of castor oil polyurethane with methylacrylate(MMA).The effects of castor oil content,initiator type and MMA content on the properties of CPUA emulsion and its film were investigated.The structure of CPUA was characterized by FT-IR.It was found that mechanical properties and water resistance of CPUA coating film and average particle size of CPUA (emulsion) increased,and viscosity of CPUA emulsions and glossiness of CPUA film decreased with increasing of MMA and castor oil contents,the optimal MMA and castor oil contents were determined to be 20%-33% and 20%-25%,respectively.Using azo-bis-isobutyronitrile(AIBN) and potassium persulfate(KPS) as composite initiator (increased) the monomer conversion.The property-tests show that CPUA exhibits the films of excellent mechanical (properties) and good water-resistance.

Key words: polyurethane-acrylate, waterborne polyurethane, castor oil, hybrid emulsion