The effects of some boron compounds on kraft pulp and paper properties produced from scot pine chips

In this study, kraft, kraft-KBH4, kraft-NaBH4, kraft-Etibor 48, kraft- Etidot 67, and kraft-colemanite cookings were made using chips of Pinus sylvestris L. Kraft cooks were done under the constant cooking conditions. NaBH4, KBH4, Etibor-48, Etidot-67 and colemanite were used as digester additives in different ratios (2% and 4%). Also, 0.75% cationic starch (CS) was added to all pulp samples as dry strength agent. Thus, the effect of CS addition on paper properties was observed. The strength and optic properties of resulting pulp were compared. Kappa number of boron compounds added pulps were higher than control pulps except of 2% KBH4, 2% NaBH4, 2% and 4% Etibor-48 added cookings. Viscosity of boron compounds added pulps were lower than control pulps. Also, the addition of boron compounds to cooking liquor caused to increases in screened and total yield of pulp. The addition of 0.75 % CS to control and boron compound added pulps caused to decreasing in tear index and brightness of paper and increasing in tensile index, burst index, TEA, and stretch of papers. On the other hand, the effect of CS addition on opacity of paper was statistically insignificant. In both CS added and CS-free papers, strength properties and brightness of paper was decreased with the increasing amount of some boron compound adding to cooking liquor. In some boron compounds, this difference was not statistically significant (P>0.05). On the other hand, differences in opacity of papers were statistically significant (P<0.05). But, these differences were not significant in paper industry. Consequently, the best results in terms of screened and total pulp yield and pulp brightness were determined in NaBH4 and KBH4 added pulps compared to addition of other boron compounds. In addition, the best results in terms of strength and optical properties of papers were determined in NaBH4, KBH4, Etibor-48 and Etidot-67 added pulps, respectively.