Abstract: Synthesis of rosin polyether ester defoamer was studied in terms of approaching the optimum experimental condition of synthesize and tests of properties. The results for rosin polyether ester show that: dosage of p-toluenesulfonic acid 0.12%, reaction temperature 160-200℃, reaction time 6-7 h.Increase of relative molecular weight (M_w) of PO-EO polyether is favorable to defoaming and antifoaming abilities of fatty alcohol polyether,at n_PO:n_EO 64-78:10-12, or ratio value 7.25, defoaming and antifoaming abilities of the optimum; For rosin ester of two functional groups, M_w of polyether greater than 4 000,is favourable to defoaming and antifoaming abilities. Howerer, when M_w is greater than 7 000, dispersibility in water declines,which is unfavorable to defoaming ability.Mass ratio of EO in polyether influences defoaming ability. When EO accounts for 10% of rosin polyether ester, defoaming ability is the optimum.

Key words: defoamer, rosin polyether ester, fatty alcohol polyether