| With the improvement of printing technology and enlargement of recyling rate of the secondary fiber, the more and more serious demands for envirmental protection, companies want to increase profit. Because of above factors which push the pollution-free surface sizing chemicals to grow vigorously. But the stability and solid contents of domestic emulsion are low. Styrene butyl-acrylate microemulsion has small diameter and excellent film-forming property which can improve the properties of domestic emulsion. So one kind of styrene butyl-acrylate microemulsion as surface sizing agent was synthesized which had less dosage of emulsifier, small particle size and high solid content, excellent water repellent property. The paper studied the synthesis methods, factors and applications of styrene butyl-acrylate microemulsion as surface sizing agent. At the same time, the light scattering technology, GPC, FTIR, AFM, SEM and so on were used to analyse properties of emulsion, the Cobb value tester and other testers were used to analysis. So the excellent precipe were found out.Some factors and ascertained some conditions were analysed according to raw materials and polymerization conditions. Molecular weight regulator had key effect on molecular weight of styrene butyl-acrylate polymer so that it could affect the water resistance of the polymer emulsion. The alteration of pH can impact on the decomposition rate of initiator and have effect on the polymerization rate of polymer so that it can decrease the properties of polymerization and impact on the water resistance of surface sizing paper and other physical properties about the paper. Through comprehensive analysis, comparing, according to save raw material and energy: The dosage of regulator was controlled from 0.2～0.4%; The concertration of initiator was 0.01 mol/L, the initial pH was neutral or be on the strong acidic condition (during pH 3). The result showed that the total conversion of styrene butyl-acrylate polymer was rather high; gel was very small, the Cobb value of surface sizing papers was rather low, the strength properties of surface sizing papers were higher than waterleaf papers.Lab optimize: At first, the DOE was used to design six factors (monomer ratio, dosage of emusifier, dosage of functional monomer, dosage of initior, rection temperature and stirring rate) by two level with Minitab—a mathematics analytical software. The figures of main effect about Cobb60 value were analysed. Then the Box-Benhnken was used to design the experement with the three factors. Response surface methodology and optimal design were used to analyse the viscosity of emulsion, particle size, gel of emulsion and Cobb of papers. The relative molecular weight of optimal polymer was Mw=133401, dispersion coefficient was 1.04. Average diameter of polymer particles were 97nm, solid content was 40%,stability of emulsion was over 5 monthes when the dosage of emusifiers was 1.6%. Styrene butyl-acrylate microemulsion which was low dosage of emulsifiers and high solid contet was synthesized. At last, Comparing styrene butyl-acrylate microemulsion in lab with siliconized acrylic emulsion as surface sizing agent and water repellent agent. I used different mixed ration of polymer and starch to confect surface applicator fluid which was sized on the base reproducing paper. The result showed that the Cobb fitted the predicted value well and. The cobb could down to 23.1 g/㎡ when the oven dry weight ration of styrene butyl-acrylate polymer and starch was suited well. The whiteness of papers sized was not impacted but the strength property of sized papers by styrene butyl-acrylate was improved to different level than papers by silicone-acrylate emulsion.
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