Study On The Preparation Mechanism Of Sae Surface Sizing Agent By Chitosan Emulsification

With the steady growth of national economy,people are paying more and more attention to environmental protection day by day,which also puts forward new environmental protection requirements for additives in paper products.As a product that people come into contact with in their daily life,paper products take up a higher and higher proportion in the economic life.But the paper products due to structure and porous composition,is easier to absorb water,affecting the subsequent use.Therefore,the green and non-polluting emulsifier used to improve the paper surface properties and water resistance of sizing agent has become the main research direction.Chitosan were used as non-reactive and reactive emulsifier to study the effect of the prepared SAE emulsion,and furthermore the effect of combination and comparison of chitosan and SDS on the properties of SAE emulsion was also studied.The detailed study included the following parts.1.In this paper,styrene and butyl acrylate were used as hard monomer and soft monomer respectively in emulsion polymerization,N-hydroxymethy lacrylamide was used as functional monomer,and ammonium persulfate was initiator.Styrene-acrylic emulsion with narrow particle size distribution,good stability and excellent water resistance were prepared by seed emulsion polymerization process.The products were characterized by FT-IR,SEM,laser particle size analyzer,Cobb,viscometer and optical microscope.Through the research of chitosan(CS)dosage,pH of CS aqueous,rotating speed,chitosan molecular weight,DD and the effect on the properties of emulsion was studied,the results showed that the desirable situation for chitosan is:with the dosage of chitosan of 2%(according to the usage of monomer),pH of CS aqueous equals to 6 and emulsifying speed is 22000 r/min.Under this condition,the styrene acrylic emulsion had good water resistance,and had good stability at the same time.2.Biodegradable chitosan,as a reactive emulsifier,made the full use of the hydrophilic group and hydrophobic groups.Its active hydrophilic and amino groups were involved in the preparation process of SAE surface sizing agent as functional monomer in the emulsion polymerization,making full use of the self-emulsification function of the chitosan and replacing synthetic organic emulsifier,reducing conventional emulsifier pollution to the environment.Chitosan can be used as the reactive emulsifier in the synthesis of styrene-acrylic emulsion.Compared with traditional emulsifier,the emulsion synthesized by chitosan acting as emulsifier can form a dense film on the surface of the paper and enhance the water resistance of the paper.The particle size of SAE emulsion prepared with chitosan as reactive emulsifier is mainly distributed between 111nm-250nm,and about 75%of the emulsion particle is distributed between 114nm-177nm,with narrow distribution and small particle size.And the Cobb value under the chitosan emulsion is about18.47g/m~2 while the Cobb value with SDS is about 105g/m~2,both of which are lower than the original paper(207g/m~2).SAE emulsions prepared by SDS as emulsifiers were mainly distributed between 50-88.9nm.The particle size distribution of SAE emulsion synthesized by OP-10 was wider and larger and the Cobb value is around 40g/m~2.3.The effects of different molecular weight chitosan on the properties of SAE styrene-acrylic emulsion were studied.The particle size distribution,water resistance after sizing,storage stability,SEM and infrared spectroscopy of styrene-acrylic emulsion were studied.The results showed that the particle size of styrene-acrylic emulsion decreased with the increase of the molecular weight of chitosan,and the PDI also decreased,indicating that chitosan had better emulsifying performance.Among the three kinds of emulsion prepared by various molecular weight chitosan,the molecular weight of 150000 improved the stability of styrene-acrylic emulsion obviously.When the molecular weight of chitosan was 100,000 and 150,000,styrene-acrylic emulsion prepared by chitosan had a better emulsifying performance and improved the water-resistance of the paper after sizing.When the molecular weight of chitosan was 150,000,the prepared styrene-acrylic emulsion had a better water resistance and stability.4.The possibility of SDS emulsifying SAE styrene-acrylic emulsion with chitosan was studied.The results showed that the color of SAE emulsion changed from blue to white with the increase of chitosan content,the overall size of latex colloidal particles increased,the size distribution gradually widened,and the overall distribution of uneven trend was obvious;Cobb value test results showed that when the proportion of CS:SDS equaled to 1:2,the paper had a better water resistance.