The main points to pay attention to in the process of producing special paper

The multi-layer slanted mesh former distributes pulp in multiple central pulpers and sizing in layers in the headbox. It adopts unique rectification and layering technology to realize the layered forming of fibers in the forming area, which can achieve two-layer, Three or more coats of sizing. In the production of slanted nets, the on-site control of the quality of papermaking and the process parameters of normal operation should be carried out.

Internet Concentration

The Internet concentration must first ensure the quality of copying, especially long fibers. Under the premise of quantitative determination, the sizing concentration is the main parameter that determines the amount of sizing. The adjustment when the sizing concentration is low will cause a large change in the amount of sizing. If the concentration is adjusted from 0.03% to 0.02%, the amount of sizing will increase by 50% .

Slurry web speed difference ratio

The speed difference between pulp and web is an important factor affecting the forming quality and the anisotropy of sheet properties (fiber direction arrangement).

Operation should pay attention to the following:

(1) The pulp speed is not allowed to be higher than the wire speed. Fourdrinier wire forming allows the speed ratio of pulp to wire > 1, but not in slant wire forming, it will cause the pulp layer deposited on the wire in the initial forming to be destroyed by the scouring of the pulp flow, and form a wavy pulp block on the wet paper sheet, which has been produced. Practice confirmed.

(2) The pulp wire speed ratio should be adjusted according to the aspect ratio required by the paper, and the corresponding law of MD/CD and pulp wire speed ratio should be established through feedback and summary of quality data.

(3) Production practice has proved that on the premise that the forming quality meets the requirements, a larger speed difference between the pulp and the web can be adopted, which is beneficial to prolong the dehydration time.

Dehydration differential pressure

The dewatering pressure difference is the dynamic parameter to ensure the dewatering of the inclined wire. It is to complete the whole process of dewatering smoothly and evenly under the constant dewatering pressure difference, so as to ensure the good bulk and air permeability of the paper sheet.

Dehydration volume control and dehydration curve

The speed of dehydration directly affects the forming of the oblique wire. If the dehydration is too fast, it is easy to cause excessive loss of fine fibers in the initial deposit layer of the slurry, thereby aggravating the surface difference and the possibility of occurrence; while the dehydration is too slow, delaying the forming process - after the waterline position The dehydration speed depends on the selection and distribution of the dehydration amount in each zone of the dehydration box.