Introduction
In the process of paper production and quality control, pulping is a key process parameter to measure the degree of fiber processing. It directly affects the fiber's morphological changes, binding ability, and ultimately, the physical structure of the paper. The purpose of this paper is to systematically analyze the influence of pulp degree changes on a number of physical strength indexes of paper, and to provide technical reference for laboratory testing and production process optimization.
Detection principle
Pulp degree, usually expressed in °SR (Schober degree), is an indicator that characterizes the water filtration performance of pulp suspensions. Its physical significance reflects the comprehensive effect of the increase of specific surface area, fine fiber and hydration degree of fiber after pulping treatment. The test is usually performed according to the Schober sizing meter, which is determined by measuring the filtration time or amount of water filtration for a specific volume of slurry. The degree of beating is positively correlated with the degree of fiber treatment, and its change is directly related to the bonding force between the fibers and the forming structure of the paper.
Effect of beating degree on fiber morphology and bonding strength
With the increase of pulping, the fibers undergo external fine fibrosis, internal fine fibrosis and longitudinal filament brooming. This results in a significant increase in the specific surface area of the fibers and increased hydroxyl group exposure, resulting in a denser network structure through hydrogen bonding during drying. The increased bonding between fibers is the root cause of most physical strength improvements in paper. However, excessive beating can also lead to a decrease in the average length of the fibers, which can negatively affect certain strength indicators.
Analysis of the response of different physical strength indicators to pulping degree
The sensitivity and response trend of various physical strength indicators to the change of pulp degree are different, which mainly depends on the structural properties of the paper on which they depend.
| Tensile strength | With the increase of beating degree, it usually shows an upward trend, due to the increase of the bonding area and bond strength between fibers. |
| Bursting strength | It is similar to the trend of tensile strength and is highly sensitive to fiber bonding. |
| Tear degree | It may rise at the initial stage, but decrease due to the decrease in fiber length at too high a pulping degree. |
| Folding resistance | Benefiting from increased bonding and improved fiber flexibility, it usually increases with increased beating. |
| Rigidity | The changes are complex, which are affected by the combination of the strengthening of the bonding force and the change of the stiffness of the fiber itself. |
Analysis and discussion
For quantitative analysis, slurry samples with different beating degrees can be prepared by laboratory handprints, and the physical strength can be tested according to relevant standards. Typical data trends indicate that the relationship between most strength indicators and beating degree is not linear. In the lower pulping range, the strength increase rate is faster. After reaching a certain range, the improvement tends to flatten or even an inflection point. For example, tearing often begins to decline after a certain degree of beating. This inflection point can be seen as the equilibrium point at which the negative effect of fiber length begins to exceed the positive effect of binding. The goal of optimizing the beating process is to find a range of excellent overall performance in key strength indicators for a specific grade.
Conclusion
Pulping degree is the core process variable that regulates the physical strength of paper. It has a systematic impact on various strength indicators by changing the fiber morphology and bonding force. In actual production and laboratory quality control, it is recommended to adopt the following strategies: first, clarify the core strength requirements of the target grade; Secondly, the relationship between pulp degree and strength of the pulp raw material is established through systematic experiments. Finally, under the premise of ensuring the feasibility of the process such as water filtration performance, the beating degree is controlled within the range of the best comprehensive performance of the target strength. Continuous monitoring of pulp degree and correlation with physical strength testing is an effective way to achieve stable and optimized paper performance.