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Through studying on the filler basic characteristics or modification to satisfy thepapermaking requirement, it’s important for the sustainable development of papermaking,therefore, the filler modification or functionalization has become a popular area of research.The ground calcium carbonate (GCC) was modified by coating with starch-sodium stearatecomplex, the paper strength performances and filler retention were both improved; theresearch provided useful references to the GCC modification and the industrial application.Firstly, the filler basic characteristics such as, particle size distribution, Zeta potential andstarch coating weight were studied. The experimental results indicated that, the bigger sizeand the more starch coated layer of the modified GCC particles, the less their negative effecton the paper strengths and whiteness, the starch modified GCC had a higher retention ratecompared to the unmodified GCC. The Zeta potential is the main factor of filler retention, theZeta potential was-14.5mV, the filler retention was the best, and the paper had the best paperstrengths when the Zeta potential was-5.91mV. For a given ash content, the strengths ofmodified GCC were much higher than those of paper with unmodified GCC, in other words,at the same paper strength, the modified GCC filled paper had more ash content, therefore, thebrightness will not be negatively affected and the cost will be reduced by using more fillersbut less fibers.Secondly, the preparation technology of the modified GCC was investigated. Theinfluencing factors including the starch concentration, gelatinization stirring rate, complexstirring time, complex stirring time, GCC concentration, coating time etc were studied byone-factor method. The orthogonal experimental results showed that when the dosage ofstarch is100%weight of GCC, the dosage of sodium stearate is3%weight of GCC, thecoating temperature is85the coating stirring time is40min, the modified GCC filled paperhas good strength and brightness, the opacity reduced. Through the analysis of particle size, itshowed that the size of modified GCC increased obviously compared with unmodified GCC,and the particle size distribution was evenly and narrow. Through the analysis of SEM, it showed that the size and surface morphology of modified GCC changed greatly, the surface ofmodified GCC was well-coated and turned softly and smoothly, and the coating layer coatedseveral GCC particles together. All these proved that it has made the surface of GCC generatea starch layer successfully. Meanwhile, the modified GCC had good anti-sheer force.At last, the influence of modified GCC filled paper on paper sizing performance andfiller retention were studied, and compared with the traditional GCC filling process. Theexperimental results showed that at the same condition, the modified GCC filled papercompared with unmodified GCC filled paper had higher sizing degree and filler retention. Atthe same CPAM addition, the filler retention of modified GCC filled paper was higher thanthe unmodified GCC. At the same AKD dosage, modified GCC filled paper had a lower Cobbvalue and lower filler retention compared with unmodified GCC filled paper. It shows thatmodified GCC can reduce the addition of AKD and CPAM, and reduced the cost.
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