| Compared with other traditional defoamers of emulsifying silicone oil and polyether defoamers, polyether modified polysiloxane (PMP) has abundant merits with its unique molecular structure. such as better stability and defoaming properties even under some extremely formidable conditions such as high temperature, strong acid, as well as strong alkali, so PMP would have wide application prospect in liquid detergent.Firstly, a number of polyether (PE) with molecular weight (Mn) around 1000, and the proportion of n(EO) and n(PO) ranging from 1:1 to 1:4 were synthesized with alkali as the catalyst in high pressure reactor. The final product PMP was prepared by polyhydrosiloxanes (PHS) and PE, the terminal group was reacted with acetic anhydride.The optimal reacting conditions upon the reaction of Si-H were systematically studied with several factors such as the content of Si-H within PHS, feeding process, proportions of the reactants, the amount of catalysts. The appropriate conditions of hydrosilylation reaction were as follows:the quality range of Si-H 0.1 mol/100 g, n(C=C):n(Si-H)=1.2:1, the amount of catalyst at 40 ppm (calculated with the effective mass of platinum), the temperature at 80℃, the reaction time at 2 hr. In this way, the PMP product with a maximum conversion of Si-H of more than 92% was obtained.The paper also studied on the compounding of PMP prepared above with emulsifier and thickener. Therefore a kind of defoaming agent formulation with good stability and high defoaming efficiency obtained was as follow:7-8% PMP,2.0% Span/Tween,0.5-0.7% hydroxyethyl cellulose (HEC) and the rest water. It could be applied in household liqiud detergents.In addition, compared with emulsion silicone and polyether deformers, the practical effect of PMP prepared above on liquid detergents was studied. The results indicated that PMP has better defoaming effect and less impact on detergency with the addition level 0.04% into liquid detergent. |
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