Preparation And Application Of Chitosan's Derivatives As A Multifunctional Chemical In Papermaking Industry

With the rapid change of papermaking technologies, such as increased paper-machine speed, increased use of twin-wire former, further closed water circuit and increased use of recycled fibers, the wet-end of papermaking environment is becoming more and more complex. Many of the materials used in papermaking process are excellent microbiological nutrients, so the microorganisms cause various problems in the papermaking process. Slime deposits can cause defects, holes or even sheet breaks. This can have considerable impacts on the production and paper quality. Therefore, highly efficient and shear-resistant paper chemicals are needed to meet the challenge.According to our research, we get (N-(glycidyltrimethylammonium) chitosan chloride (GTCC)) after chitosan was modified by quaternary ammonium salt, this derivative has more positive charge; and it is a very good retention and drainage aids. At the same time, it improves paper strength and it has antibacterial effect.The first part of this paper deals with the factors affecting the preparation of chitosan quaternary ammonium salt. The preparation conditions of cationic chitosan are optimized. In order to obtain the optimum process conditions, the effects of some factors, such as dosage of etherifying agent, reaction time, reaction temperature on reaction ratio, degree of substitution were studied. The chitosan quaternary ammonium salt was characterized by Fourier transform infrared spectroscopy (FTIR).Secondly, a series of GTCCs were used as retention and drainage aids for bleached hard wood and softwood pulps. Their capabilities of retention and drainage increased as their charge density and dosage increased. The mechanisms of GTCC were discussed using the SEM (scanning electron microscope). The effects of shear rate, contact time, GTCC dosage, pH value on the First Pass Retention (FPR) of dynamic conditions were investigated.In the third part, we investigated the antibacterial effect of chitosan quaternary ammonium salt. Some bacterium, namely E. coli, Aspergillus's Niger, Saccharomyces cerevisiae were used as the test samples. The effect of different dosage, degree of substitution, pH, temperature, different ions and different heat treatment condition on the antibacterial performance was discussed.