1. Strictly control the bleaching process to avoid excessive bleaching and reduce strength
The hardness of the kraft paper bag slurry directly determines the amount of bleaching liquid. In determining the amount of bleaching liquid, the hardness of each pot will always be different, and the pulp temperature will be different in different seasons, especially in the north, and the temperature difference between winter and summer can reach above 15 °C. Therefore, the bleaching time of each pulp material is also different, up to 0.5 h or more, so the bleaching time must be strictly controlled. Otherwise, due to the extension of the bleaching time, although the whiteness of the pulp can be increased to a certain extent, the paper is reduced. The mechanical strength, and the timing of the yellowing of the paper is increased, and the quality is not stable.
2. Strictly control the cleanliness of the pulp to avoid calcium accumulation in pipelines and equipment
The production requirements of refined kraft paper bags are sizing, and the bleaching liquid remaining in the pulp generally does not affect the sizing. However, in the practice of production operations, in order to ensure the whiteness requirements of the semi-bleaching slurry, some factories add a small amount of bleaching liquid to the pulp pool after bleaching to ensure the whiteness of the slurry, perhaps because the bleaching slurry is not completely washed, resulting in drifting. The post-mortem still contains a large amount of calcium base, which is subjected to the sizing station, and the free rosin acid anion causes the accumulation of calcium rosinate, and the sulfate ion in the alum causes CaSO4 accumulation. This kind of deposit combines with rubber and resin and has a certain viscosity. It is very simple to deposit on the transportation pipelines and equipment.
3. Correct understanding of the difference between pulp whiteness and paper whiteness, suitable for reducing the whiteness of the slurry
Strictly control the whiteness of the semi-bleached pulp of refined kraft paper bags. On the one hand, it is the requirement of paper color, on the other hand, the requirement of paper strength, the whiteness is improved, the mechanical strength of paper forming is reduced, so it should be reasonable in production. The semi-bleeding whiteness is controlled, and the whiteness reaches the required together to obtain the maximum paper strength.
4. Moderate calendering to improve paper gloss and whiteness
In order to improve the gloss of the paper, the groove is pressed and pressed, and finally can be calendered by a 4~6 roller calender to improve the gloss of the paper, reduce the double-sided difference of the paper, and properly improve the whiteness of the paper together. degree.
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