Document Type : Research Paper
Author
Associate Prof., Dept. of Wood and Paper Science and Technology, Cha. C., Islamic Azad University, Chalous, Iran
Abstract
Background and aim: Fluting paper and Kraft liner paper are among the most important grades of paper produced in the pulp and paper industry, particularly for the manufacture of corrugated board. Fluting paper is typically made from a mixture of hardwood fibers using the Neutral Sulfite Semi-Chemical (NSSC) pulping process adding some softwood pulp, while kraft liner paper is produced from similar raw materials through the Kraft pulping process also adding some softwood pulp. However, due to limitations in wood supply and competition for primary raw materials, a significant portion pulp for these papers in Iran is recycled fibers, such as OCC and converting mill rejects. This study employs Gas Chromatography-Mass Spectrometry (GC-MS) to precisely identify and compare the organic compounds present in corrugated paper and kraft liner paper. The primary aim of this research is to evaluate the impact of various chemical constituents on the structural and functional properties of these two types of papers. Additionally, the study attempt to find these chemical roles in optimizing production processes and improving the overall quality of the final product within the paper manufacturing industry.
Materials and Methods: In this study, fluting paper samples were collected from the production line of machine No. 2 at Mazandaran Wood and Paper Mill, and kraft liner paper samples were obtained from Chooka paper mill in Gilan. Initially, the ash content and extractable substances in the samples were quantified according to TAPPI standards. The extractable substances were then separated from the paper pulp using acetone as a solvent. The remaining extracts were transferred to glass vials, to which BSTFA (N, O-Bis(trimethylsilyl)trifluoroacetamide) reagent was added. The samples were heated in a water bath at 70°C for one hour before being injected into the GC-MS system for analysis. Compound identification was performed using retention time chromatograms, the Quats index and Adams table.
Results: GC-MS analysis of the fluting paper identified a total of 76 compounds, with the most abundant being benzaldehyde (20.44%), benzene methanol (5.32%), 9-octadecenoic acid (5.16%), bis(2-ethylhexyl) phthalate (4.33%), gamma-sitosterol (1.34%), and beta-sitosterol (1.01%). These compounds primarily consisted of aromatic hydrocarbons and natural fatty acids. In contrast, GC-MS analysis of kraft liner paper identified 28 compounds, with the major components being bis(2-ethylhexyl) phthalate (28.21%), hexadecanoic acid (24.25%), 9-octadecenoic acid (11.67%), octadecanoic acid (10.45%), hexadecane (7.12%), pimaric acid (2.06%), 1,2-benzenedicarboxylic acid (1.17%), squalene (1.40%), and syringyl aldehyde (0.31%). These substances were predominantly industrial plasticizers and fatty acids, which play an important role in the composition and functional properties of Kraft liner paper. The GC-MS analysis of fluting paper also revealed the presence of compounds such as p-xylene, benzaldehyde, dibenzyl, formylmorpholine, and benzyl alcohol, which were not detected in kraft liner paper. Additionally, light alkanes (such as decane, dodecane, and nonadecane) and phytosterols, specifically beta- and gamma-sitosterol, were uniquely present in fluting paper, supporting the hypothesis of differences in fiber sources or the use of specific additives in fluting paper production. In contrast, phenolic and aromatic compounds detected in fluting paper may be derived from adhesives, inks, or residual chemicals in the manufacturing process. For kraft liner paper, compounds such as abietic acid, pimeric acid, and isocunabic acid were identified, which were absent in fluting paper. Additionally, long-chain hydrocarbons such as tetracosane and squalene were found specifically in this sample, indicating the potential use of softwood fibers or non-fibrous additives like rosin.
Conclusion: The comparison of GC-MS profiles between fluting paper and kraft liner paper revealed that both grades of paper share common chemical constituents, including long-chain alkanes and natural fatty acids. Furthermore, bis(2-ethylhexyl) phthalate, an industrial plasticizer, plays a significant role in improving the mechanical properties of both paper types. The observed differences in specific compounds, such as the presence of aromatic compounds and light alkanes in fluting paper and long-chain hydrocarbons and resins in kraft liner paper, suggest variations in fiber sources, pulping processes, and the use of additives. These differences could provide valuable insights for optimizing paper formulations and enhancing the quality of paper products.
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