Sythesis Of Amino Polyether Modified Silicones And Their Application As Defoaming Reagents

Amino polyether-containing silicones, which combine the remarkable properties ofpolyether-silicones and amino-silicones, are a new kind of particular silicone surfactants thatare attracting broad interest across the world. They are non-toxic and environmentallybenign. Despite these advantages, there are scarece examples describing their applications asdefoaming agents. In this paper, the synthesis and defoaming properties of aminopolyether-containing silicones are presented.The synthetic route for amino polyether-containing silicones empolys the introduction ofamino polyether chain into silicone backbone by utilizing polyether amine as the source. Thesynthetic route starts with hydrogen silicone and consists of two majorsteps,hydrosilylation and ring-opening nucleophilic addition. Firstly, hydrosilylation reactionbetween methyl end or side-chain hydrogen silicone and allyl glycidyl ether would get anintermediate epoxy-modified silicone. This reaction was conducted in toluene in thepresence of a platinum catalyst H2PtCl6and isopropanol. The optimal technology wasobtained as follow: reaction temperature is80oC for200min,dosage of catalyst is30~45ppm, the mole ratio of n(C=C)/n(Si-H) was1.2:1.The epoxy-modified silicone werecharacterized by IR,1H-NMR; Secondly, the epoxy-modified silicones generated fromhydrosilylation undergo further ring-opening nucleophilic addition reaction of the epoxygroup with polyether amine (M、 D、 ED series) to deliver the desired aminopolyether-containing silicone products. The optimal technology was obtained asfollow:reaction temperature is60oC for150min,the mole ratio of the epoxy group withamino-group was1:1. The products were were characterized by IR,GPC,TGA,surfacetension and cloud point determination.Subsequently, the defoaming applicability of the resultant amino polyether-containingsilicones is studied and compared with commercially available defoaming reagents. Fourkinds of amino polyether silicone were compared with commercially available defoamingagent by defoaming performance comparison. These amino polyether-containing siliconesshow good defoaming ability and are comparable to commercial ones without any treatmentin some cases. Furthermore, it was shown that after the composition of our aminopolyether-containing silicones with some co-surfactants, the defoaming ability of ourproducts increases substantially. Taking E-M-600as an example, the best composition of thedefoamer compounds was optimized as followings:(1) The dosage of fumed silica was8%~9%;(2) The mass ratio between SS and SSE-20was2to1for compound emulsifier andits dosage was2.7~3%;(3) The thickener hydroxyethyl cellulose (HEC) was selected and itsdosage was0.5%;(4) The mass ratio between E-M-600and silicone cream was6to4;(5)The methods of phase inversion was chosen as the emulsification method.Finally,the amino polyether-containing silicone defoamer were under severe conditionsof defoaming performance test and commercial antifoam performance comparison. The aminopolyether-containing silicone defoamer were resistant to high temperature,acid,alkali.thedefoaming performance was close to the commercially available defoamers.