Pulping Temperature
During the pulping process, due to the friction between fibers and fibers, as well as between fibers and the grinding discs, frictional heat is generated, causing the temperature of the pulp to rise. The extent of temperature increase varies depending on the pulping conditions. Free-form pulping, with a shorter pulping time, results in a relatively small temperature increase. In viscous pulping, with a longer pulping time, the pulp temperature is more likely to experience a significant increase. For example, in the pulping of capacitor paper, due to the longer pulping time, the temperature may rise above 60°C, and this temperature will indirectly affect the stability of the use of Polyester Forming Fabric in the subsequent papermaking process, so appropriate adaptation considerations should be made in advance.
If the paper material temperature is too high, the following several side effects may occur:
1.It affects the paper sizing effect, resulting in a decline in the sizing performance.
2. Release the resin from the sulfite wood pulp to create a barrier for the resin.
3. This may cause the fibers to undergo dehydration, significantly reducing the fiber's ability to absorb water and expand. As a result, the pulping time must be extended to achieve the required degree of pulping. However, the extension of the pulping time will cause changes in the properties of the pulp, thereby affecting the compatibility with Polyester Forming Fabric and potentially leading to a decrease in the uniformity of formation during papermaking.
4. Affecting the physical strength of the paper. Taking sulfite wood pulp as an example, the paper material was treated at 20℃ and 60℃ respectively to achieve a final pulp consistency of 50SR. The paper was then made and its physical strength was measured. It was found that at a pulp temperature of 60℃, the tear length was 22.7% lower than that at 20℃, the tear resistance was 74.3% lower, and the burst strength was 43.2% lower. However, only the water absorption performance and air permeability were improved. This is mainly because higher temperatures tend to cause the dehydration of the paper material, significantly reducing the swelling degree of the paper material. During the pulping process, the mechanical cutting effect increases, ultimately leading to a decrease in the fiber bonding force in the paper. This change in fiber bonding force will further affect the supporting and shaping effect of Polyester Forming Fabric on the paper sheet, and indirectly influence the final quality of the paper.
During the production process in the factory, the effect of pulping is influenced by the season and region. It is usually found that the high temperature in summer causes some troubles for the pulping process. In severe cases, cooling measures need to be taken to avoid excessive loss of the heat resistance of Polyester Forming Fabric due to the high-temperature pulp, thereby extending its service life. In winter, when the temperature is lower, there is no problem of excessive pulp temperature. Polyester Forming Fabric can achieve the best forming performance under an appropriate temperature environment.
