Study On The Preparation And Application Of Cationic AKD

The neutral/alkaline sizing has been used since 1980s in China. After nearly 20 years of efforts,the neutral/alkaline sizing has been developed rapidly,especially the AKD sizing developed most rapidly in a variety of neutral/alkaline sizing papermaking technology.From the traditional cationic starch to the current cationic resin as the cationic agent,by which AKD is emulsified and cationization so that AKD can be adsorpted on the fibers.In order to enhance the retention ability and sizing effect of AKD, the positive charge of AKD emulsion should be raised.A large molecular sizing agent modified AKD was prepared through the reaction between alkyl ketene dimmer (AKD) and polyamide polyamines(PPC) then, cationization by epichlorohydrin (EPI) .The synthesis and application conditions were studied as follows.In the first part of this paper,through the single factor experiment,the optimum conditions for the synthesis were determined: m(AKD):m(PPC)=5:6, m(EPI):m(synthetic derivatives)=3:7.Under these synthesis conditions,the cationic AKD emulsion was dispersive,which also sized well in the neutral sizing.Secondly,the structure and physical properties of the cationic AKD were analyzed by using infrared spectrometer instrument and laser particle size distribution analysis.The results showed that the size of cationic AKD emulsion was small ,the distribution of size was narrow,and the Zeta potential of emulsion was high.The results also showed that the emulsion with high positive charge was self-retention strongly,easy-emulsification and dispersive,which also had better stability and mobility.Thirdly,the sizing of cationic AKD and traditional AKD in the neutral sizing were studied and the results showed that:(1)The positive charge and self-retention ability of cationic AKD sizing agent were higher than those of traditional AKD sizing agent.(2)The sizing effect of cationic AKD on bleaching hardwood kraft pulp was better than that of traditional AKD.(3)Adding filler was bad to the sizing effect in the neutral sizing,but the sizing effect of cationic AKD was better than that of traditional AKD under the same dosage of filler.(4)The sizing degree of cationic AKD was 45s to 52s from the pH 6.5 to 10,which indicated that the sizing effect of cationic AKD was very good and it could be used in a wide range of pH.