The all acrylate emulsion was prepared with hydrophilic monomer methyl methacrylate (MMA) and hydrophobic monomer butyl acrylate (BA), and the influence of the reaction temperature(T),the concentration of initiator([I])，emulsifier([E]) and the monomer ratio(fMMMA) on the particle size and its’ distribution(PSD) was investigated for semi-continuous seeded emulsion polymerization. The experimental results show that the evolvement rule of PSD is changed from narrow to wide and then returned to narrow in the whole process of polymerization. The influence of [E], [I], fMMA and T on PSD is various, PSD tends toward narrow at the same reaction time when [E] increases, [I] decreases and fMMA increases; but the influence of T on PSD is not unidirectional, PSD tends toward narrow when T is raised from 70℃ to 85℃, but when T is up to 90℃, PSD tends toward wide rapidly in nucleation stage, particle dispersion index Fmax is more than the value at 85℃, and Fmax returns to narrow slightly in later continuous polymerization stage. The particle size analysis shows that for semi-continuous seeded emulsion polymerization, the particle size increases at all time, but the PSD is narrow to wide during the nucleation stage, then becomes narrow after nucleation stage, finnally keeps a narrow dispersion.
