Synthesis And Application In Surface Sizing Of Starch-based Styrene-acrylic Emulsion

In the production of packaging paper,the proportion of waste paper raw materials is increasing.The repeated use of waste paper leads to a serious decline in fiber quality.Poor fiber quality will cause difficulty in papermaking,and it will be difficult to meet the application requirements for paper quality.Therefore,a large amount of auxiliary agents needs to be added to make up for these problems.Surface sizing,as a means to effectively improve paper strength,water resistance,and printability,has become a necessary process for packaging paper production.Therefore,it is great practical significance to research and develop surface sizing additives with high efficiency,environmental protection,stable performance and good adaptability.In this paper,the research discusses the synthetic conditions of starch-based styrene butyl acrylate emulsion(referred to as starch-based styrene-acrylic emulsion)and the application effect on the paper surface sizing process.The purpose is to improve the regeneration performance of synthetic polymer surface sizing agents and reduce costs.In the paper,the polymerization method of starch-based styrene-acrylic emulsion is soap-free emulsion polymerization.Cationic starch(CS-8)as a dispersion system and graft,Styrene(St),butyl acrylate(BA)are monomers,and dimethylaminoethyl methacrylate(DMAEMA)is a cationic functional monomer.Ammonium persulfate acts as an oxidant for cationic starch,H2O2-FeSO4 is the initiating system.They was used to prepare the starch-based styrene butyl acrylate emulsion.The influence of polymerization conditions on the performance of the emulsion was optimized.The synthetic emulsion was characterized and its application effect was studied.Optimized polymerization conditions:the ratio of soft and hard monomers m(St):m(BA)is 1.5:1,the ratio of starch and monomers m(CS-8):m(monomer)is 1:2,the amount of functional monomer DMAEMA is 1%,and the theoretical solid content of the emulsion is 30%.Under these conditions,the stability and sizing performance of the synthesized emulsion are good.Particle size analysis showed that the particle size distribution of starch-based styrene-acrylic emulsion was concentrated.More than 90%of the particles have an average particle size distribution between 86nm and 88nm.The average particle diameter was 87.4 nm.Potential analysis showed that the Zeta potential of the emulsion particles was 17.82mV.Infrared analysis confirmed that styrene and butyl acrylate successfully participated in the graft polymerization with starch.Thermogravimetric analysis of the emulsion showed that the starch-based styrene-acrylic emulsion was a random copolymer.DSC analysis showed that the glass transition temperature of the emulsion was 47.8?.The starch-based styrene-acrylic emulsion was applied to the surface sizing of corrugated base paper.The Cobb value of the paper after sizing is 36.6 g/m2,which is 66.2%lower than that of corn starch sizing.the initial contact angle is 113.8°,and the water resistance is good.From the point of view of the physical strength of the paper after sizing,the transverse ring pressure index,longitudinal crack length,and longitudinal folding resistance times were 7.2 N·m/g,4.7 km,and 19 times.Compared with corn starch gum sizing,they increased by 44.0%,71.9%,and 171.4%,respectively.SEM analysis of the paper after sizing showed that the starch-based styrene-acrylic emulsion formed a dense sizing layer on the fiber surface.Starch-based styrene-acrylic emulsion is used in combination with biomass such as corn starch and sludge to extract protein.The research discussed the applicable properties of starch-based styrene-acrylic emulsion.The results showed that with the increase of the proportion of corn starch in the system,the water resistance and paper strength of the paper decreased after sizing.When the ratio of Cobb value is less than 75%,the decrease in water resistance is small,and when the ratio is greater than 75%,the decrease is large.From the perspective of paper strength,when the ratio of corn starch increased from 0%to 90%,the transverse ring pressure index and longitudinal crack length decreased by 28.6%and 10.2%,respectively.When the proportion of corn starch is not higher than 50%,the corrugated base paper can reach the corrugated base paper A grade quality standard after sizing.Starch-based styrene-acrylic emulsion was used in combination with sludge extracted protein for surface sizing.With the increase of the proportion of extracted protein,the water resistance and paper strength of the paper gradually decreased after sizing.The Cobb value increases less when the proportion of protein extracted from sludge is less than 50%,and increases sharply when it exceeds 50%In terms of paper strength,when the protein ratio was increased from 0%to 90%,the transverse ring pressure index,longitudinal crack length,and longitudinal folding resistance times decreased by 35.4%,33.1%,and 78.6%,respectively.When the proportion of protein extracted from sludge is less than 25%,the paper can reach the Class A quality standard of corrugated base paper after sizing.In summary,using a soap-free polymerization method,the synthetic starch-based styrene-acrylic emulsion has good emulsion stability and surface sizing performance.In addition,starch-based styrene-acrylic emulsion is used in combination with other rubber materials to have a better sizing effect.