## 3 Results and Discussion
### Physical Properties  
The surface roughness and tensile strength of toilet seat cover sheets containing 0.2% AKD, which exhibited a disintegration rate comparable to toilet paper and water-repellent properties, were compared under different freeness conditions. Figure 4: Comparison of sizing degrees and contact angles of the disposable toilet seat cover sheets according to varying freeness and AKD addition levels: (**a**) sizing degree; (**b**) contact angle. Surface roughness is a critical attribute of toilet seat cover sheets that directly affects user comfort. This study investigates the impact of pulp freeness on the surface roughness of toilet seat cover sheets containing 0.2% AKD (alkyl ketene dimer). Figure 5 illustrates the surface roughness of these sheets prepared under different freeness conditions. Toilet seat cover sheets were prepared by incorporating 0.2% AKD into pulp stocks with varying levels of freeness. The surface roughness of the sheets was measured to assess the tactile smoothness perceived by users. Freeness, a measure of the drainage rate of a pulp slurry, was adjusted through refining processes, which fibrillate the fibers and potentially alter the surface characteristics of the final product. The results indicate that refining slightly improved the surface roughness of the toilet seat cover sheets, making them marginally smoother. However, no significant difference in surface roughness was observed based on changes in freeness levels. This suggests that the tactile smoothness of the cover sheets, as perceived by users, remains almost identical regardless of the freeness of the pulp used. The slight improvement in surface roughness with refining can be attributed to the mechanical processing of fibers, which creates a more uniform and less coarse fiber network. Refining causes fibers to undergo compression and shear forces, leading to fibrillation and the creation of finer fiber elements that contribute to a smoother surface. Despite this, the study found that variations in freeness did not significantly impact the surface roughness. The consistent tactile smoothness across different freeness levels suggests that users will have a similar sensory experience with the toilet seat cover sheets, irrespective of the processing variations in pulp freeness. This uniformity in surface roughness is beneficial from a manufacturing perspective, as it allows for flexibility in the refining process without compromising user comfort. It is necessary to note that rough surfaces provide more area for bacteria to attach than smooth surfaces [39]. Moreover, disposable cover sheets are manufactured from biodegradable cellulose fibers and have many voids, making them more susceptible to bacterial contamination. Therefore, considering the rough surface structure, the presence of many voids, and the characteristics of cellulose fibers, it is essential to recognize that disposable cover sheets require antimicrobial treatment to prevent bacterial contamination. These findings have practical implications for the production of toilet seat cover sheets. Manufacters can achieve the desired surface smoothness without heavily focusing on adjusting freeness levels. This can streamline the production process, reduce costs associated with extensive refining, and ensure consistent product quality. The slight improvements in surface roughness due to refining are beneficial but not critical, allowing for greater flexibility in manufacturing parameters. Tensile strength is a key mechanical property that determines the durability and performance of toilet seat cover sheets. This study investigates the impact of pulp freeness on the tensile strength of these sheets [40; 41]. Toilet seat cover sheets were prepared from pulp stocks with different levels of freeness, which were adjusted through refining processes. Freeness, measured as the drainage rate of a pulp slurry, influences the extent of fiber bonding and network cohesion [42].