Study On Improving Hydrophobicity And Ring Crush Strength Of Corrugated Base Paper By Surface Sizing

Hydrophobic property and ring crush strength are two indicators that corrugated base paper manufacturers are most concerned about.Practice has shown that surface sizing of paper and adding appropriate additives to the starch gelatinizing solution are effective methods to improve both the hydrophobic properties and the ring crush strength of paper.Due to the continuous rise in the price of basic chemical raw materials and the continuous growth in logistics and transportation costs,some solid surface sizing agents that can impart hydrophobicity to paper have begun to be used and are favored by papermaking enterprises in recent years.However,it is not very clear how effective the use of this type of solid sizing is,and how to properly evaluate and explain its sizing application effect and mechanism,leading to a general lack of correct understanding of this new type of surface sizing agent by papermaking workers.In this study,a solid surface sizing agent based on ferrous sulfate and aluminum sulfate was developed to achieve a better cost performance ratio and solve the problems of insufficient hydrophobic properties and ring crush strength of corrugated base paper after surface sizing.On the basis of small scale trials,through pilot production applications,problems arising from the large-scale use of solid adhesives for surface sizing were identified and solutions were provided,with a view to providing guidance for actual production and application.The main research contents and results are as follows:Firstly,sulfate and chloride salts of sodium,magnesium,zinc,iron,ferrous,and aluminum were selected to investigate the effect of their combination with starch and surface sizing on the sizing effect of corrugated base paper.From these,ferrous sulfate and aluminum sulfate with better effects were selected for the subsequent preparation of solid surface sizing agents.Then,ferrous sulfate and aluminum sulfate are prepared into a solid surface sizing agent in a certain proportion,and starch is replaced with 10%,20%,30%,and40%of the proportion.Combined with the appropriate use of high-temperature amylase,the mixture is gelatinized to prepare a corresponding surface sizing solution.The surface sizing of corrugated base paper is carried out,and the hydrophobic properties and structural properties of the paper are investigated by various means,The results showed that as the amount of solid sizing increased from 0 to 40%,the water droplet penetration time increased to 3 hours,the Cobb₆₀value decreased to 32g/m²,and the contact angle increased to 120°,the penetration rate of liquid water into the interior of the paper significantly slowed down,and the hydrophobic property of the paper sample significantly improved.The composite sizing solution helps to form a denser and smoother sizing layer,reducing the roughness,average pore size,and porosity of the paper,thereby also reducing the permeability of water to the paper.Finally,the problems encountered in the pilot scale application of solid surface sizing agents were studied.These include the problem of excessive amylase usage after the use of solid adhesive,the problem of excessively dark sizing liquid color after the use of solid adhesive for surface sizing,the problem of poor moisture resistance of corrugated base paper,and the problem of increasing the ring crush strength of corrugated base paper.Studies have shown that acidity itself has a significant inhibitory effect on the activity of high-temperature amylase,and the stronger the acidity,the more significant the inhibitory effect.Al³⁺ions and the acidity generated by their hydrolysis also have a significant inhibitory effect on the activity of high-temperature amylase,while Fe²⁺ions have a more significant inhibitory effect on the activity of high-temperature amylase;By adding color suppressor A and color suppressor B with a dosage of 5%of the total amount of solid sizing to the reciprocating mixing system,the color of the sizing solution is effectively suppressed,and the color stability of the sizing paper sample can be better controlled;As for the moisture resistance of paper,research shows that in a high humidity environment with a humidity of 90%,the performance of solid surface sizing agents is comparable to that of mainstream styrene-acrylic adhesives on the market;Finally,adding an appropriate amount of PVA to the starch solid adhesive composite system for surface sizing of corrugated base paper can significantly improve the ring pressure index,and the ring pressure increase effect is most significant when the mass percentage of starch/ferrous sulfate/polyvinyl alcohol/aluminum sulfate is 76/18/4/2,compared to the paper sample without PVA,the ring pressure index increases by 12.7%.