Abstract: The aim of this study was to use enzyme-modified corn starch as an adhesive for surface sizing of boxboard and corrugated board, and to investigate its effects on the physical properties of the paperboard. Enzyme-modified corn starch was prepared using medium-temperature α-amylase, and its viscosity changes were tested. Then, the enzyme-modified starch was applied to the surface of boxboard and corrugated board, and various physical properties were tested. The optimal amount of enzyme-modified corn starch for surface sizing of boxboard and corrugated board was explored.
Keywords: Starch enzyme; Corn starch; Boxboard; Corrugated board; Surface sizing; Paperboard properties
Introduction: Corrugated board, characterized by its wide availability, low cost, ease of cutting and forming, and recyclability, is widely used in product packaging. With the popularity of e-commerce, the demand for corrugated board is increasing. However, due to the reuse of recycled paperboard in China’s papermaking industry, the strength of paperboard is generally low. During logistics, paper boxes often face problems such as easy compression and tearing, causing certain difficulties for paper box manufacturers. Starch is a natural polymer with certain viscosity and film-forming properties. However, when directly used to improve paper strength, starch has certain limitations. In order to improve the performance of starch and expand its application in the papermaking field, physical and chemical methods are usually used to treat starch to obtain paperboard with high physical properties. Enzyme-modified starch is a biological catalytic reaction that can significantly reduce the molecular weight of starch. It has the advantages of low enzyme dosage, fast reaction rate, and environmental friendliness. In this study, medium-temperature α-amylase was used to modify corn starch, and its viscosity changes were tested. Then, the enzyme-modified starch was applied to the surface of boxboard and corrugated board, and their physical properties were tested to provide a basis for preparing high-performance paperboard.
Experimental Section:
Materials and Reagents: Corn starch (grain size: 60 mesh), liquid medium-temperature α-amylase, E-type corrugated board, boxboard (basis weight: 130 g/m2).
Instruments and Equipment: Viscometer (DV2T), constant temperature magnetic stirrer, folding endurance tester, paper and paperboard thickness tester, computer-controlled paperboard stiffness tester, computer-controlled bursting strength tester, electronic universal testing machine.
Results and Analysis:
Effects of Different Enzyme Dosages on the Viscosity of Gelatinized Corn Starch: The viscosity of modified corn starch decreased with increasing enzyme dosage, indicating efficient enzymatic reaction.
Effects of Enzyme-Modified Corn Starch Surface Sizing on the Physical Properties of Boxboard:
Stiffness: Surface sizing with enzyme-modified corn starch significantly increased the stiffness of boxboard.
Ring Crush Strength: Surface sizing increased the ring crush strength of boxboard, reaching a maximum with a certain enzyme dosage.
Bursting Strength: Surface sizing had little effect on the bursting strength of boxboard.
Tensile Strength: Surface sizing increased the tensile strength of boxboard, reaching a maximum with a certain enzyme dosage.
Folding Endurance: Surface sizing slightly decreased the folding endurance of boxboard.
Conclusion: Enzyme-modified corn starch exhibited a significant decrease in viscosity, making it suitable for surface sizing of paperboard. Surface sizing with enzyme-modified corn starch improved the physical properties of both boxboard and corrugated board. Optimal results were achieved with specific enzyme dosages, providing a reference for preparing high-performance paperboard.
