Polyacrylamide in Papermaking
In papermaking process, fibers, fillers and some additives are not water-insoluble, so they are easy to accumulate in aqueous solution. Moreover between the different materials as far as possible from the incompatibility away, so it is difficult to get uniform performance and ideal strengthen paper. In order to solve the long fiber in the process of this problem, the using of polyacrylamide has following advantages:
1. improves the retention rate of fillers, pigments and so on. To reduce the loss of raw materials and environmental pollution.
2. improves the strength of the paper (including dry and wet strength).
3. improves the tear resistance and porosity to improve visual and printing performance.
The advantages of using polyacrylamide as a paper dispersant are also manifested in the fact that the product is soluble in water and forms a high viscosity liquid which promotes good dispersion of papermaking fibers and excellent paper forming effect at low added levels to improve pulp consistency And the softness of the paper, but also to improve the strength of the paper performance.
In the use of the paper coating, paper dispersant with high dispersion efficiency, paint viscosity and stability, less foam, non-toxic, non-corrosive, can improve the solid content of paint, and good mobility and scrub resistance, to keep paper gloss Degree, not easy to mold.
Polyacrylamide is soluble in water, but it its’ dissolved concentration of more than 10 percent, the solution will form a transparent gel in water and lose mobility. If a large amount of polyacrylamide is added instantaneously during the dissolution process, a dissolution system with a concentration greater than 10 percent is formed in a region of the water, making it difficult to continue the dissolution process. So must first add a certain amount of water, until the mixing leaves did not, start the mixer, so that the water cycle after adding polyacrylamide, stirring blades should not have edges and corners, blade, otherwise there will be hanging material and shear poly Acrylamide molecular chain of the adverse effects, so that the dissolution concentration is not allowed, and weaken its dispersion.
Polyacrylamide dissolved concentration is not too high. Polyacrylamide stirring time is not easy to dissolve too long, the general mixing time in 1-2 hours or so is appropriate, otherwise it will destroy its dispersion effect.
Polyacrylamide in the dissolved are not fully dissolved, there will be a small part of the incomplete dissolution of the gel group, so the application must be added to the filter equipment to prevent the gel into the paper machine, hanging net and sticky cloth Or produce paper disease.
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