Synthesis And Characterization Of Acrylate Modified Waterborne Polyurethane

In recent years, as people's awareness of environmental protection, water-based coatings research and development has attracted wide attention, and has very broad prospects for development. Water-based polyurethane emulsion (WPU) and water-based acrylic copolymer (PA) are water-based coatings which are widely used as the base material in the market. WPU and PA compared with other solvent-based coatings have many advantages:cheap, non-toxic, nonpolluting the environment, these two materials are widely used in leather, adhesives, coatings, etc. Polyurethane has excellent resistance to organic solvents, cold, temperature adaptability and flexibility, but in light of security, self-thickening, water and other aspects of defects, while acrylic latex has high mechanical strength, anti-aging, good water resistance, but a free radical polymerization in such polymer which is wear resistance, chemical resistance, organic solvent resistance, toughness and poor still sticky temperature, low temperature crisp and other shortcomings because that monomer was random at the molecular chain structure. PU and PA in the nature of complementarity between the two, so that synthesis of this new emulsion in good combination of both polyurethane and polyacrylate has become a hotspot at home and abroad.This article started from the idea of particle design. The core-shell structure with a clear acrylic modified waterborne polyurethane (PU-AC) emulsion was synthesized by using semi-continuous method including isophorone diisocyanate (IPDI), N210, dimethylol propionic acid (DMPA) as polyurethane raw materials, methyl methacrylate (MA), butyl acrylate (BA), acrylic acid ester monomer, hydroxypropyl methacrylate (HPMA) as a coupling agent, potassium persulfate (K2S2O8) as initiator and trimethylolpropane (TMP) as crosslinker. The emulsion and film property such as a-NCO/-OH ratio, the polymer PU/PA mass ratio, the amount of crosslinker, the amount of emulsifier, initiator amount, the amount of buffer,-COOH content as well as polymerization temperature was systematic on the research. First of all fixing-HPMA, initiator (KPS), buffer (NaHCO3), emulsifier (SDS) and the amount of polyurethane and acrylic ester mass ratio (PU/PA) were discussed the composition of emulsion structure and properties in the different ratio of propylene-NCO/-OH ester/polyurethane (PUA). Firstly, the results showed that emulsion stability is good and no significant changes were in appearance with the increase of the ratio-NCO/-OH. Film water absorption efficient decrease, thermal stability increases, the maximum weight loss temperature increased and the glass transition temperature are improved. Secondly, fixing the ratio of the quantity of HPMA, initiator (KPS), buffer (NaHCO3), emulsifier (SDS) and-NCO/-OH, The influence of different PU/PA ratio of PUA composition emulsion structure and properties was investigated. We draw the conclusion that the draw ratio PU/PA=1/1 timekeeping PUA hybrid emulsion obtained better overall performance. In addition, with fixing the amount of HPMA, initiator (KPS), buffer (NaHco3), emulsifier (SDS), the mass ratio constant o of-NCO/-OH and PU/PA, the amount of crosslinker on the PUA film properties was discussed. It can be draw the conclusion that the film water resistance, thermal stability and the mechanical properties are increased within a certain range with the crosslinker increases when the crosslinker 0.8% in the increase of cross linking dosage of the film have little effect overall performance. Finally, the amount of emulsifier, initiator, buffer,-COOH content as well as polymerization temperature was discussed on the emulsion and film properties. It was founded that the polymerization temperature was 80-85℃, initiator dosage was 0.4-0.6%, the amount of emulsifier was 2-4% and the amount of buffer was 0.6-1.0%, relatively which was stable emulsion. Furthermore, the gel a small amount of stability, film heat resistance, water resistance and mechanical properties were superior.By transmission electron microscopy (TEM), the particle shape and structure of PUA was characterized. The results showed that the size of core-shell particles has uniform particle size and the particle size greater than the nuclear layer which thus proves the existence of core-shell structure.