Thickness and tightness
Adjust the thickness not only according to the index, but also pay attention to the tightness. The tightness is normal at 0.72-0.73, and the thickness index cannot be simply looked at. To see whether there is deviation in the quantification according to the tightness index, first determine whether it is because the quantification affects the thickness.
1. Adjust the calender pressure: the calender can be reduced to 10bar at least
2. Adjust moisture: the greater the moisture, the lower the thickness
3. Adjust the core pulp ratio: the larger the proportion of chemical mechanical pulp, the higher the thickness, the more paper loss, the lower the thickness, and the larger the proportion of L pulp, the lower the thickness. When adjusting the proportion of paper loss, pay attention to the liquid level of damaged pulp pool and pulp tower and the combination between layers.
The core layer has the greatest impact on edge water seepage. Generally, the adjustment mainly starts from the core layer. If the edge water seepage is too large, first check whether the addition of chemicals is normal, and then make adjustment. The factors affecting edge water seepage are:
1. PH value: according to practical experience, the effect is better when the pH value is between 5.2-5.6.
2. The dosage of cationic rosin size is generally 20-25kg / T absolute dry pulp, or anionic rosin sizing agent can be used.
3. Wet reinforcer, generally 5kg / T absolute dry pulp.
4. Whether the pH value of the slurry is within the normal range.
5. Whether the retention rate and the amount of retention aid are normal.
Interlayer bonding is also a very important index of cup paper, which is normally above 140. If interlayer bonding is too high, it indicates that there is room for cost reduction. Filler consumption can be increased to prevent excess quality. The factors that have a great impact on interlayer bonding are:
1. Filler dosage: the greater the filler dosage, the lower the interlayer adhesion.
2. Cationic starch and spray starch can make the fibers have a good combination, but cationic starch can only be added to 1% of the size at most.
3. Moisture entering the dryer: the greater the moisture entering the dryer, the worse the adhesion between layers.
4. Press water: the greater the press water is, the more serious the loss of starch will be with the water squeezed out by the press.
5. Ratio of damaged paper: the free degree of damaged paper is low, so the greater the amount of damaged paper is added, the better the adhesion between layers is, but pay attention to the thickness when increasing the damaged paper.
6. Freeness of slurry: the higher the freeness, the smaller the specific surface area of fiber, so the worse the adhesion between layers.
The ash content is mainly reflected in the cost. The smaller the ash content, the higher the cost. The ash index should be more than 10%. The influencing factors of ash content are retention rate and filler dosage
Dust points and garbage
When there are many dust points and garbage, first determine which layer the dust point comes from and what it is. Soak the paper sample with boiling water. After layering, determine whether it is surface, interlayer, or which layer and what it is. Only in this way can it be easy to determine a search direction. If the direction is unclear, it will get twice the result with half the effort.
1. Whether the desander is blocked and the pressure difference is abnormal: the blockage of the desander will lead to the untreated slurry entering the good slurry, and the abnormal pressure and pressure difference will lead to the poor desanding effect. The slurry inlet pressure of desander is 2.5-3.0kg and the pressure difference is 1.0-1.5kg, which belongs to the normal range.
2. For the garbage and dust on the surface, check the positions of drying cylinder, guide roller, calender, sizing machine and light pressure, as well as the places where garbage may fall onto the paper.
The above is the analysis of common problems in cup paper production by the technical service personnel of HANGHUA Halima, for the reference of relevant papermaking technicians