Study On The Specialized Retention And Drainage Aid For Papermaking With Secondary Fiber Pulp

This paper is aiming to research the performance of retention and drainage sysem in theprocess of papermaking with secondary fiber pulp. Three kinds of different properties ofcationic polymers including M₁（medium molecular weight, medium electric charge densityN7527）,M₂（molecular weight, low electric charge density liquid N61067）and M₃（molecularweight,low electric charge density solid P₁82） were selected to be applied as singlecomponent retention and drainage system in the case of20%PCC（Precipitated CalciumCarbonate） filler dosage. Further more, the anionic microparticles CP-3and high whitenessbentonite were used to combine with M₁，M₂，and M₃to act as differents dual components andthree components system at the same PCC filler dosage.First of all, the effect of M₁，M₂，and M₃acting as single component system on retentionand drainage was studied. The results showed that among the single component systems, M₃had better ability to improve the pulp drainage performance and fines retentions rate in whichcase the ash content of paper sheet improved6.4%, fillers retention improved34.86%, anddrainage time reduced39.1%.Secondly, Three different dual components retention and drainage systems, namely N₁composed with M₁and CP-3,N2composed with M₃and CP-3and N3composed with M₁andM₃which is a kind of dual cationic system were studied.The results showed that dualretention and drainage system N2had improved the pulp drainage performance and finesretentions rate in which case the ash content of paper sheet improved7.5%, fillers retentionimproved43.2%, and drainage time reduced41.4%.At last, we studid the effect of ternary components system on the retention and drainage.The ternary components included P₁composed with M₁, CP-3and high whiteness bentonite,P₂composed with M₂, CP-3and high whiteness bentoniate and P₃composed with M₃, CP-3and high whiteness bentonite.Among ternary system, the using of M₃, CP-3and highwhiteness bentonite had better performance in which case the ash content of paper sheetincreased7.4%, fillers retention increased42.6%, and drainage time reduced35.6%.In the experiment, we measured the turbidity and cationic demand of white water in the case of different retention and drainage systems. The analysis showed that the turbidity andcationic demand of white water could be used availably to indicate and identify theperformance of retention and drainage system from another view angle.In this paper, the influence of shear rate on the performance of retention and drainagesystem was also studied. The resistance to shear influence of multi-components system washigher than single component system. For single component, it should be avoided to be usedunder too high shear rate and too low shear rate. For dual component system, the addng orderof different component was very important. In which, to obtain the optimal effect, the cationicpolymer should be added with higher shear rate and CP-3should be added with lower shearrate. For ternary component system, cationic polymer and high whiteness bentonite should beadded with high stirring rate and CP-3should be added with low shear rate.This paper also researched the impact of pH value and reaction time of differentretention and drainage systems on retention and drainage The retention and drainage systemcan be used both acidic and alkaline papermaking papermaking. With time increasing, theretention rate of filler showed increasing first and then reducing for three kinds system. ForM₃system, the effect of retention and drainage reached highest in20-40s.For the N2and P₃the effect of retention and drainage reached highest in30-50s. Then after that,with the timeincreasing more, the effect of retention and drainage would reduced relatively.Based on the comparison of production cost and effect of retention and drainage ofdifferent systems, we determined that the dual system of M₃and CP-3has optimal applicationeffect on increasing fillers and fines retention, improving drainage performance andmaintaining paper sheet strength. Furthermore this system shows higher ability to resist theeffect of fluid shear power.