Impact Study Of Chitosan Surface Sizing Agent On Paper Properties

With the development of the printing industry and the popularity of eco-friendly production concept,the improvement of paper performance has become a hot spot in the field of paper chemicals.Chitosan is a natural macromolecule material with many good properties,such as no toxicity,good reaction performance and excellent film-forming property.However,the higher price of chitosan limits its application in the paper industry.Therefore,the decreasing of the chitosan price has become the key point for its popularization.In this work,based on the film-forming and film strength of chitosan,chitosan surface sizing agent was studied.This can reduce cost and expand its application in the paper industry.The quality of the sized paper was investigated after the treatment with different molecular weights chitosan,carboxymethyl chitosan(CMCS)and CMCS/oxidized starch mixture.The results showed that the molecular weight of chitosan had a significant effect on the application of surface sizing agent;the viscosity of CMCS/oxidized starch mixture was related to the molecular weight;the molecular weight of chitosan should be controlled in 9.1×105~4.2×105 in order to obtain a better operating performance.The synthesis of CMCS was investigated in order to obtain a product with better application performance.The CMCS was prepared at 60℃,for 4h,with the mass ratio of chitosan(M=9.1×105),sodium hydroxide and monochloroacetic acid was 1:3.5:4.Under these conditions,the degree of substitution of CMCS was 0.763 and the derivative was water soluble.When CMCS/oxidized starch mixture was blended as 10:0.06,and sizing on paper was controlled at 1.5±0.2g·m-2,the surface strength of paper was increased approximately 19% compared to oxidized starch sized paper.The printing and inkjet printing quality of sized paper were investigated after treatment with polyvinyl alcohol and CMCS/polyvinyl alcohol mixture.Results indicated that the surface sized by CMCS/polyvinyl alcohol mixture could obtain better chromaticity and the printed content had better water-resistance.The application of cationic carboxymethyl chitosan wasconducive to the increasing of ink-printing.When the amount of carboxymethyl chitosan was 2.0%,applied at 2.0±0.2g·m-2,compared to the polyvinyl alcohol sized paper,the paper surface strength raised approximately 15%,tensile strength raised approximately 17%,the discount rate raised approximately 16%.The cross-linked chitosan was prepared with carboxymethyl chitosan,PAE resin and acrylamide using the ammonium persulfate as initiator.The synthesis process of the cross-linked chitosan and the effect of the cross-linked chitosan/AKD sizing agent mixture on the water resistance were studied.The cross-linked chitosan was prepared at 65℃,for 3h,with the mass ratio of CMCS and acrylamide was 1:2.The cross-linked chitosan was conducive to the performance of AKD sizing agent.The modified AKD sizing agent was prepared by blending the cross-linked chitosan and AKD sizing agent as 1:1.Compared to AKD sizing agent,paper sized with the modified AKD sizing agent could achieve the similar Cobb60 value,and the paper surface strength could be improved approximately 14%,tensile strength could be improved approximately11%.