Study On Using Shell Powder As A Filler In Papermaking

In the papermaking industry, fillers, as second only to pulp fiber in terms of their added amounts, which can occupy 20% to 40% of the paper material composition, is one of the most important components of modern paper industry. In recent years, along with the increasingly exhausting of resources and rapid development of economy, the development of novel categories of mineral filler engineering has become a popular research in the field of pulp and paper, especially for the low cost and green filler which derived from solid waste. In China, the shellfish breeding is developed, while large amounts of shells are usually disposed as garbage in coastal areas since a long period. Shells are mainly composed of calcium carbonate(~95%),while calcium carbonate is one of the most common fillers in papermaking, therefore, it is feasible to use shell powder as paper filler to substitute for calcium carbonate.In this paper, the physical properties, surface morphology and web properties of shell powder filler and the properties of filled paper were investigated, which were compared with the properties of commercial precipitated calcium carbonate(PCC) under the same condition,then the feasibility of using shell powder as papermaking filler and its advantages were discussed. The effect of particle size of shell powder on the properties of filled paper were studied on this basis. All of these could be provided as references in application of shell powder in web of papermaking.The surface morphology, particle size and distribution and physical properties of shell powder filler were characterized. Shell powder exhibited spindle-shaped scalenohedral and uniform particles, and the small particles gathered together in clusters. The average particle size of shell powder was 0.44 μm and the particle size distribution was uniform, the brightness was 91.45 %ISO, the sediment volume was 5.35 mL/g. It was feasible to use shell powder as a paper filler.15% of shell powder was respectively filled in KP reed pulp, acidic sulfite reed pulp and bleached hardwood pulp to confirm the best content of cationic polyacrylamide. The Zeta potential of pulp, the physical properties and ash content of filled paper and the retention ofshell powder were analyzed. Finally, the appropriate content of cationic polyacrylamide was decided at 0.02% based on the total mass of oven-dry pulp and filler. Then better properties of filled paper and higher filler retention could be acquired.Then the filling performances of shell powder were explored by investigating the influence of shell powder on filler retention, the strength properties and optical properties of handsheets when different dosage of shell powder were respectively filled in KP reed pulp,acidic sulfite reed pulp and bleached hardwood pulp. Shell powder was considered to be feasible as a paper filler in KP reed pulp, acidic sulfite reed pulp and bleached hardwood pulp.When the filler content was between 10% and 15%, better filling influence was considered.While the filler content was 10%, comparing with the condition without loading any filler respectively, the tensile index, tear index and burst index of KP reed pulp hand sheets filled with shell powder was decreased respectively 4.11 N·m/g, 0.73 mN·m2/g and 0.22 kPa·m2/g,while the brightness, opacity and light scattering coefficient was decreased respectively0.70 %ISO, 4.56% and 9.32 m2/kg; the tensile index, tear index and burst index of acidic sulfite reed pulp hand sheets filled with shell powder was decreased respectively 6.55 N·m/g,0.74 mN·m2/g and 0.28 kPa·m2/g, while the brightness, opacity and light scattering coefficient was decreased respectively 2.12 %ISO, 0.81% and 5.15 m2/kg;the tensile index, tear index and burst index of bleached hardwood pulp hand sheets filled with shell powder was decreased respectively 6.31 N·m/g, 0.79 mN·m2/g and 0.54 kPa·m2/g, while the brightness, opacity and light scattering coefficient was decreased respectively 1.13 %ISO, 1.84% and 8.67 m2/kg;when the content of filler was 10%, the filler retention of shell powder loading in KP reed pulp,acidic sulfite reed pulp and bleached hardwood pulp were respectively 80.77%, 59.02% and77.26%. Therefore, shell powder, as a paper filler, was more appropriate for paper making by using KP reed pulp and bleached hardwood pulp.When compared with PCC filled paper at the same condition, shell powder was showed significant advantages in improving the opacity and light scattering coefficient of paper.The effect of different particle size of shell powder on the strength properties and optical properties of the KP reed pulp hand sheets and the filler retention were analyzed. The influence of particle size on the properties of filled paper when the filler retention was the same were also discussed. When the filler content was the same, the tensile index, tear index and burst index were increased with the increasing of particle size of shell powder, while the brightness,opacity and light scattering coefficient were decreased. The filler retention of shell powder was raised when the particle size of shell powder increased. When the filler retention was 20%, the filler retention of 1# shell powder and 2# shell powder were respectively 79.97% and 79.87%,which were almost the same, while the the tensile index, tear index and burst index of hand sheets filled with 1# shell powder were lower than that of hand sheets filled with 2# shell powder, the brightness, opacity and light scattering coefficient were higher than that of hand sheets filled with 2# shell powder. As the particle size of 1# shell powder was smaller than 2#shell powder, when the filler content was 20% and the filler retention of 1# shell powder and2# shell powder was almost the same, it was observed that 1# shell powder with smaller particle size showed bigger damaging on paper strength while obvious improvement in optical properties of filled paper for the same kind of shell powder filler.