| One-side coated white manila board is a good packaging material. It has excellent printing performance, good processing performance, and lower price than white cardboard, coated paper. No doubt it occupies about 2/3 of coated paperboard consumption. Printability and strength properties are highly required for this product, and they are closely related to demensional stability, stiffness, ring crush compression resistance and burst properties which can be regarded as the most important properties to this board grade. The traditional testing of these properties are taking samples according the standards and then testing the samples in the lab. The results are passably in reflecting the paperboard quality. While the traditional testing process has some fatal disadvantages, it’s complex, time-consuming and information feedback delay, thus they are insufficient in monitoring the production and giving in-time suggestions on how to change production conditions.On the other hand, the above important traditional propertes have close relationship with elastic properties. Many researches disclosed that elastic properties could be characterized by Tensile Stiffness Orientation (TSO) which can be tested by TSO Tester. The test results can be fed back imediatelty to the mill process and used to optimize the runnability of the papermachine quickly. In China, some articles have been written giving basic introduction on the principle, testing method and the influencing factors of TSO, but TSO has remained as an unfamiliar property to most papermakers. Also, despite that many mills have TSO testers and they have been used to analyze and solve problems in papermaking, very few detailed public reports describing the procedures of process adjustment and the results could be seen, due to confidential reasons. Thus the great potential of TSO Tester in playing better roles in paper manufacturing is far from well established.To demonstrate the advantages of TSO measurement, this research used a TSO Tester to optimize the production of a one-side coated white manila board machine. With the help of the continuous multidirectional TSI data produced by the TSO Tester, and with the combination of process parameter information, the relationships between TSO properties and parts of the operation parameters were created. Both jet/wire ratio and recirulation ratio were found to have an influence on TSOAgie value and its profile; TSI value can be controlled by changing the ratio of quality pulp in the furnish and grammage variation; and drying was found to be the process that influences the TSICD profile most.Next, the advantages of TSO properties over traditional physical properties in predicting the quality of manila board were demonstrated, with the help of Principal Component Analysis. It was found that bending stiffness can be predicted easily from TSI based on the well-known Markstrom’s formula. Bursting index varies according to different basis weight, but slight increase in bursting index can be seen with the increase of TSIMD/CD ratio. This result indicates that the bursting property can be predicted by the TSIMD/CD ratio profile. Good linear relation between RCT and TSI value were also found, indicating that using TSI as an index to avaluate the RCT value and compression strength has good feasibility. Obviously, TSO measurement, with its great advantages in rapid and accurate testing, is superior in predicting the compression strength and stiffness property to the traditional test methods which are laborious, complex and time-consuming.In the final step, the runnability problems of the manila board machine and its optimization were focused. TSO tester was used to measure the tensile stiffness orientation angle (TSOangle), the machine-direction tensile stiffness index (TSIMD), the cross-direction tensile stiffness index (TSICD), and their ratio (TSIMD/CD) before and after the changing of process variables. The data were related to product qualities and process problems. Then optimization suggestions were given and their validities were tested. We proved that TSO tester can be used to predict paper quality and machine runnability problems in a quick way, especially problems involved with the headbox, such as slice lip open profile, jet/wire ratio and recirculation ratio. The analysis and optimization process proved that using this methodology can greatly shorten trial steps and save time in troubleshooting, with the results of improved paper quality and production efficiency, therefore it is a very convenient and effective optimization tool. |
