| Our country is a big tanning country,and has become the center of world leather industry. In tanning process, only about 30% of raw hides can be turn into leather and generate a lot of solid waste. As one of the largest leather producing countries, China generates annually around 1.4 million tons of chrome-contaminated waste shavings. These solid waste due to lack of effective use of means, will have great harm to the environment, at the same time is also a kind of waste of resources. Paper sizing agent has the characteristics of large dosage, wide range, especially the annual output of 20 million tons of paper box board, dosage of sizing agent demand is very big. In this work, collagen was modified by emulsion polymerization using butyl acrylate and styrene as monomers, and ammonium persulfate as the initiator. The modified collagen emulsion(MCE) obtained in this manner was used for surface sizing of corrugating medium, and the sizing process was optimized.The collagen used in experiments was taken from factory, and there are eight different molecular weight of collagen. Their functional properties were investigated in the earlier studies to choose what kind of molecular weight of collagen is better for modification, including the solution p H value, conductivity, solubility and emulsification. Results show that the collagen which molecular weight is 7000 Da has good performance. Its solubility, emulsification, emulsifying activity is better than other molecular weight of collagen.The molecular weight distribution of collagen is wide, and has impact on the synthetic sizing agent emulsion. In this paper, the ultrasonication was used to optimize the particle size of collagen, the propriate conditions to get a collagen in normal trend size will be found. And the structure of collagen protein before and after ultrasonic treatment was characterized by FTIR, TG, XRD and other means. The results show that the ultrasonic power in a certain time and can change the particle size distribution of hydrolyzed collagen, and continue to increase the ultrasonic time and power is little effect on the particle size; when the ultrasonic time is 10 min, the ultrasonic power is 360 W, the in this case the particle size of collagen has normal distribution, and the particle size is small. Hydrolyzed collagen through before and after ultrasonic treatment, the molecular structure does not change.The collagen extracted from leather wastes were then modified with styrene and butyl acrylate to get emulsion products, and the emulsion was applied to surface sizing on corrugated paper separately, by investigating the mechanical properties and water resistance of paper after sizing, and optimization of synthesis process. Experimental results show that when the collagen and monomer mass ratio of 1:1. 5, the dosage of initiator is 3.5% of the monomer, the proportion of the monomers styrene and butyl acrylate is 1: 1, the reaction time was 2 hours.And when the synthesis conditions were further optimized,we can know in the synthesis process, the smaller of the collagen solution used, the particle size of sizing agent emulsion was also smaller;And after sizing, the mechanical properties and water resistance of paper were better. Comprehensive considerations, in the process of synthesis we don’t have to adjust the p H value of collagen solution.FTIR spectra of specific absorption peak intensity increases and ester groups of C=O bonds occurs; XRD analysis shows that the crystallinity of modified collagen increased; and the pattern appears in the modified collagen STA second platform, and collagen are described modified collagen graft reaction did occur.The collagen emulsion sizing performances were researched, and the sizing process was optimized. Modified Collagen emulsion has good sizing property, can significantly improve the mechanical properties of the paper, but due to its having a hydrophilic group, water resistance is poor. paper sized by styrene acrylic emulsion compound with modified collagen emulsion, when the ratio is 1:1, the performance of paper is best, the ring crush index and tensile index of paper increased 79.2% and 63.4%, respectively, the water absorption weight in 60s(Cobb60) of sized paper reduced to 40 g/m2. When paper sized by modified collagen emulsion compound with AKD emulsion, the best ratio is 3: 1, the sizing effect shows that the ring crush index and tensile index of paper increased 54.2% and 47.7%, respectively, the water absorption weight in 60s(Cobb60) of sized paper reduced to 34.7 g/m2.Modified Collagen emulsion, styrene-acrylic emulsion, and the starch compound with sizing, when the ratio of 4%:6%:90%, paper after sizing has good mechanical properties and water resistance.The SEM morphology of paper surface after sizing suggests that the paper properties of water resistance of the has certain relevance with its surface structure.The hydrolyzed collagen, polyvinyl alcohol, styrene, and butyl acrylate were used to synthetic sizing agent, the optimum synthesis condition is: the amount of the initiator was 4%, most preferably butyl acrylate and styrene ratio was 1: 3, PVA /(ST + BA) is 1: 5, and collagen and the total mass of monomer ratio is 4: 5, when the reaction time was 3.5h.Paper sized by Quaternary copolymer alone, sized by quaternary copolymer and styrene-acrylic emulsion, quaternary copolymer and starch, and sizing performance were compared. And the results show that, paper sized by quaternary copolymer alone, quaternary copolymer sizing complex with starch, have good mechanical properties. But when paper sized by quaternary copolymer couple styrene-acrylic emulsion, the water-resistant of paper is better. This is the same conclusion as modified collagen emulsion sizing effect. |
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