Utilization of Calcium Carbonate-Coated Wood Flour in Printing Paper and Their Conservational Properties

Yung Seo,Dong Kang,Jung Han

doi:10.3390/su11071867

Abstract

Wood flours (WFs) are bulky lignocellulosic materials that can increase the bulk and stiffness of paper. To be used in printing paper for replacing chemical pulp, WFs were first fractionated by a 200-mesh screen to improve smoothness; second, they were coated with calcium carbonate by an in-situ CaCO3 formation method (coated wood flours, CWFs) to improve brightness. The performance of CWFs for printing paper was compared to those of bleached wood flours (BWFs) and bleached chemical pulp. Equivalent brightness and much higher smoothness were obtained for the CWFs compared to the BWFs. Furthermore, BWFs caused a significant loss of yield and required wastewater treatment in the bleaching process, while the CWFs increased the yield greatly by attaching CaCO3 to the wood flours, and caused no wastewater burden. An accelerated aging test showed that the CWFs caused lesser brightness and strength loss than the bleached chemical pulp and BWFs. CWFs still had room for improvement to replace chemical pulp, but showed slower aging in optical and close strength properties.

Highlights

Wood flours (WFs) are used in the filler layer of multiple paperboards and papers to achieve high bulk [1,2,3,4,5]
Hydrogen peroxide bleaching was applied to the WFs (5 wt% H2O2 based on dried wood flour weight, sodium silicate, pH13 initially controlled by NaOH, liquid ratio 1:10, 80 ◦C, 90 min. duration)
The wood flours (WFs) that passed through a 200-mesh screen, were added to the bleached chemical pulp in 5% and 10% by weight after H2O2 bleaching (BWFs) or after CaCO3 coating (CWFs) to replace the bleached chemical pulp, but turned out to be slightly inferior in brightness and strength properties other than stiffness

Summary

Introduction

Wood flours (WFs) are used in the filler layer of multiple paperboards and papers to achieve high bulk [1,2,3,4,5]. If WFs can be used in printing paper without causing optical and physical problems, the bulk and stiffness will be greatly improved, and again, basis weight reduction may be possible while essential properties are kept at acceptable levels. To improve the brightness of WFs, Shin et al [7] applied an alkaline pulping process. Kim et al [8] applied a bleaching process They prepared WFs that passed 200mesh screen, and applied two-step bleaching process by using chlorine dioxide and peroxide. Their results showed that the addition of bleached wood flours still gave low brightness and high roughness, but high bulk in printing paper. Kim et al [9] tried to add an optical brightener in addition to wood flour bleaching, and obtained more improved brightness by addition of optical brightener

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