Synthesis And Application Of Water-based Dispersion Cross-linked Cationic Polyacrylamide As Retention And Drainage Aid

Water-based dispersion cross-linked cationic polyacrylamide (CPAM) is a new cationic aid of retention and drainage, which has the effect of anti high shear and high conductivity. The CPAM with high molecular weight was synthesised in the aqueous solution of ammonium sulfate using acrylamide (AM) and 2-methacryloxyethyl trimethyl ammonium chloride (DMC) as two main monomers, N,N-methylene bis-acrylamide (MBA) as crosslinker and PDMC (self made) as stabilizer; Dilatometer method was used to study the reaction kinetics of retention and drainage aid of cross-linking CPAM. The polymerization kinetics equation and the apparent activation energy of CPAM was obtained using mathematical fitting method and the result was confirmed by back calculation. The optimum conditions for the use of cross-linked CPAM compared with linear CPAM was further studied by applying it in fine paper.The results showed that, when the mass fraction of comonomers was 15%, Initiator, MBA and sodium methylallyl sulfonate (SMAS) were 0.11%,40mg/kg and 600mg/kg, and respectively, reaction temperature was 56℃, The obtained CPAM showed optimal performance. Under high shear and high conductivity conditions, the cross-linked CPAM had better retention and drainage performance than a commercial linear CPAM emulsion.The retention and drainage aid of cross-linking CPAM was synthesized with 2,2’-azobis (2-methylpropionamide) dihydrochloride(V50) as the initiator, AM and DMC as the monomers. The reaction kinetics was studied with a dilatometer, and various factors such as monomer concentration, initiator concentration, monomer ratio, the dosages of cross-linking agent and dispersant were discussed.The results show that the polymerization rate equation is Rp=K[M]199[I]0.71, the apparent activation energy is 103.59 KJ·mol-1, the reaction rate constant expression is K=4.001×1017·exp(-12.43/T), and the calculated values fit well with experimental values.The retention and drainage effect of cross-linked CPAM" water-in-water "emulsion was tested by applying it in the handsheet for fine paper, and compared with linear CPAM. It was demonstrated that better retention and drainage can be obtained when the amount of CPAM is 0.04% and the contact time is 30 seconds. Compared with linear CPAM, cross-linked CPAM has a much better retention and drainage effect in high salt and high shear conditions, The first-pass retention is 91%, the filler retention is 85%, and the Schopper-Riegler beating degree (expressing of drainage) was reduced 14°SR.Water-based dispersion cross-linked CPAM was made in a chemical plant by designing successfully the production process and equipment.The retention and drainage effect of CPAM was very well when tested it. The white water concentration was reduced to 2-5%, and the waterline removed 0.7m when the CPAM was applied to mill consisting of bentonite and Polyaluminium Chloride(PAC).