عنوان مقاله [English]
The study is carried out to survey the effect of using cationic polymers for cationization of precipitated calcium carbonate (PCC) synthesis’s suspension on paper properties.
Paper is made by lignocellulosic material and inorganic compounds. Inorganic compounds are including functional additives and process aids which mineral fillers belong to functional additives. Todays, due to shortage and high price of lignocellulosic raw material, papermakers raised the consumption of mineral fillers. However, mineral fillers though have numerous advantageous like improvement in optical properties, printability, reduce production costs, also induces disadvantageous like weak distribution in paper structure, loss of mechanical properties, less retention, instability of production line and increasing effluent pollution loading.
Singh et al (2011) optimized the application of chemicals for high yield papers using PCC thereby starch and silica. They claimed that cationic starch with medium cationic charge induces highest retention value, while cationic starch with high charge density results in most drainage.
Studies by Shen et al (2010) showed that modified-PCC with carboxyl methyl cellulose (CMC) / alum improved filler retention and also optical properties like brightness and opacity in comparison with control sample significantly. They also found that paper without mineral filler have higher strength than those have fillers, but mechanical strength of paper contained unmodified filler and paper contained modified filler hadn’t significant difference.
Eventually, considering issues like production cost, effluent and its pollution loading, enhancement of paper machine speed, and also necessity of production paper with appropriate formation and quality, it’s necessary to study the interactions of various additives in paper, depending on their application.
Material and Methods
Synthesis of PCC carried out by injecting the carbon dioxide (CO2) to lime solution, or releasing the CO2 thereby hydrolysis of di-methyl carbonate in alkaline media. Cationic polymers including cationic starch, polyacrylamide, poly amino polyamide-epichlorohydrin and polydadmac in 15% level were used in synthesis suspension of calcium carbonate. Finally, paper properties filled with modified-PCC were examined.
It’s found that cationic suspension of different polymers lead to variation on synthesized calcium carbonate as papermaking filler. Generally, papers filled with modified-PCC compared with papers contained industrial calcium carbonate and those had synthesized calcium carbonate, improved optical and mechanical properties in neutral media except tear strength.
In this study, values of ash in papers contained modified calcium carbonate increased compared with papers with industrial calcium carbonate and those with synthesized calcium carbonate in neutral media. Bulk of papers with modified fillers reduced, but the air resistance, tensile and burst strengths and also optical properties increased. Normally, since mineral fillers have no bounding ability with cellulose fibers, so due to restricted and weaker bonds between fibers and also lack of appropriate formation and lack of stress distribution as a result, tensile and burst indices of paper decreased respectively. However, by synthesizing calcium carbonate in cationic suspension, because of improved bounding area induced by presence of cationic polymers in surface of precipitated calcium carbonate and uniform distribution of mineral filler in paper different response found.