The Study Of Unsaturated Paper Strength Agent

With the development of world’s paper industry, strength agent has become increasinglywidespread and more important. In order to meet environmental protection requirements, it isurgent to find a new, environmentally friendly and energy-saving strength agent. This studyadopted a new cross-linking mechanism which could form hydrophobic network between fibersby radical polymerization of unsaturated double bonds to enhance the wet strength of paper.This paper attempted to prepare an unsaturated epoxy resin.This paper systematic study of the preparation and application of unsaturated epoxy resinwith raw materials of Bleached Hardwood Kraft Pulp(BHKP), Bleached Softwood KraftPulp(BSKP) and wastepaper pulp.First, the synthesis conditions of unsaturated paper strength agent was studied. Thesuitable synthesis conditions showed as follows: the each monomer molar ratio of1:1:1isadded into the reaction system at40℃for5hours. Compared with other conditions, the yield ofthis polymer under above-mentioned conditions was higher, and the application effect was moreideal. The raman spectrum of polymers, epoxy value and unsaturation degree were detected, theresults showed that the synthetic polymer contains epoxy groups, carbon-carbon double bondand so on. The result of TGA showed that the polymer had good thermal stability. The storageconditions and other characteristics were analysed, the results showed that the storagetemperature has a greater effect on epoxy value and application effect. The epoxy value contentand wet-strength reduced by more than half at room temperature for storage, while at lowtemperature for storage, epoxy value only lost9.10%, and wet strong index reduced by19.7%.Second, it was studied the influence of beating degree, raw material, dosage of polymer forapplication effect of unsaturated epoxy resin. At the same time, the micro-structure ofhandsheets was analyzed. The results showed that unsaturated epoxy resin used in the papersheet, the strength properties of the sheet improved significantly, especially the wet strengthproperties. Using SEM techniques, the fracture of handsheet without polymer and the fractureof handsheet with polymer were observed. The results showed that handsheets with polymer,which fracture mainly results from the fracture of fibers, significantly improved inter-fiber bonding. Contact angle measurements showed that the handsheets with polymer couldeffectively improved the water resistance, and with the increase of the dosage, the sheet ofwater resistance was also improved.Third, it was studied the influence of different kinds of retention and drainage aid for Zetapotential and application of polymer. The results showed that the guar gum which had a similarstructure of cellulose was a fitting retention aid. Not only could quickly adsorbed on the fibersurface, but also provided hydroxyl for the formation of hydrogen bonds between the fibers.When the dosage of retention aid was0.3%, the Zeta potential of pulp tend to isoelectric point,at this time, the wet strength of handsheets with guar gum was improved by41%and15%compared to CPAM and PEI.Finally, the effects of different curing technique on the application of unsaturated paperstrength agent were studied, hoping to use more environmentally UV curing technology toreplace traditional high-temperature curing technology. The results showed that compared withnatural light curing, UV curing and high temperature curing technology could significantlyimprove wet strength properties of the sheets, and the high temperature curing could keep thewet strength of sheets more significant. After high temperature curing, the wet strength of paperwas up to11.5N m/g, and slightly higher than the effect of UV curing. But compared with thenatural light curing, wet strength of paper improved200%by using UV curing.