## 3 Results and Discussion
### Antibacterial Test  
The incorporation of antibacterial agents into toilet seat cover sheets can provide significant hygiene benefits, particularly in public or high-traffic restrooms where the risk of bacterial contamination is higher [47]. Figure 7 highlights the antibacterial properties of toilet seat cover sheets containing 0.2% AKD (alkyl ketene dimer) and an organic antibacterial agent. The organic antibacterial agent (Zinc Omadine(tm), zinc pyrithione, Ahsung Fine Chemical Co., Ltd., Pyeongtaek, Korea) easily blends with cellulose fibers. Pyrithione-based agents exert antibacterial activity in the cover sheets by destroying cell membranes.  
Figure 6: Tensile strength and surface roughness of toilet seat cover sheets made from pulp stocks with different freeness.  
A powder-type organic antibacterial agent was chosen to enhance the retention and efficacy of the antibacterial properties within the fiber network. To attach organic antibacterial agents to cellulose fibers, cationic retention aids were used. The cationic retention aid acts as a bridging agent to attach organic antibacterial agents to cellulose fibers. It works by neutralizing the negative charges on both the fibers and the antibacterial agents, forming stable complexes that ensure the antibacterial agents are effectively retained in the paper. The toilet seat cover sheets were prepared with varying concentrations of the antibacterial agent to determine the minimum effective concentration.  
The findings indicate that toilet seat cover sheets made solely from pulp fibers or with antibacterial agents added at concentrations below 1% showed no noticeable antibacterial effect. The antibacterial activity was significant only when the added antibacterial agent constituted at least 1.0% of the total dry weight of the pulp fibers. This threshold concentration is crucial for ensuring the effectiveness of the antibacterial properties in practical applications.  
The results underscore the importance of the concentration of antibacterial agents in achieving significant antibacterial activity. At concentrations below 1%, the antibacterial agents are insufficient to provide any noticeable effect, likely due to inadequate coverage and interaction with bacteria. However, when the concentration reaches or exceeds 1%, the antibacterial agents are more effectively retained within the fiber network, providing a robust antibacterial effect. The use of powder-type organic antibacterial agents is particularly advantageous for this application. The powder form enhances the retention of the agent within the fiber network, ensuring sustained antibacterial efficacy [48]. This is essential for maintaining the hygiene benefits of the toilet seat cover sheets over time.  
The incorporation of antibacterial agents in toilet seat cover sheets offers additional hygiene benefits in environments with high bacterial contamination risks. Public and high-traffic restrooms, in particular, can benefit from this added layer of protection. The antibacterial properties help reduce the spread of germs, promoting a cleaner environment and providing peace of mind for users with health concerns or heightened awareness of hygiene. However, it is also true that strict restrictions on usage are necessary, as there are reports indicating that even low concentrations of antimicrobial agents can cause disruptions in aquatic systems [49; 50].