working principle of paper retention and drainage aid

- Jan 18, 2019-

l Retention

In papermaking, fillers are the auxiliary materials with the largest dosage, and the particle size is generally 0.2-10 mesh, while the copper net mesh used  in paper machine is relatively large, ranging from 40 to 100 mesh, which is equivalent to 150-250 µm.Generally in the process of forming, only about 50% of the packing retention rate, the remaining half will be lost with the white water.Retention aids can coagulate and flocculate, so they can be used to improve the retention rate of fine fibers and fillers in paper and reduce the solid content of fine materials in water.

A wide variety of retention agent, according to the structure and property of the retention agent can be divided into inorganic and organic polymer, surfactant, including organic polymer retention agent with a total of 23 kinds, mainly organic amine (ammonium salt derivatives is given priority to, with polyoxyethylene (PEO), starch, etc., among them with polyacrylamide the most representative.


Ø Bridging adsorption

CPAM products are based on charge adsorption and bridge interaction to realize retention.Different from the traditional product with few bridging adsorption points (top and bottom two points), the branched chain of quansen paper making agent can provide a large number of different adsorption points, so that the number and size range of particles selected for bridging adsorption by single molecules is greatly expanded!

Ø Charge of adsorption

CPAM products of another adsorption, retention and principle is charge by gather into cationic monomer in the polymerization process to realize, but simply add and aggregation, and can't make the cationic monomer and molecular chain good integration, a lot of product ion monomer dissociation outside the chain, or with the adhesion strength of the chain is very small, easy to spread.

Quansen papermaking retention and drainage aids by not saturated adsorption technology, the ion monomer solid adsorption on the belt of branched chain, the ion monomer is really effective ion monomer, if a product has no adsorption technology, so this kind of product can't compare with quansen paper retention and drainage aids, especially in low speed, unit retention and papermaking, adding more even if the product ion monomer, nominal ion degree is high, vain, also easy to discharge directly with water.

By introducing other copolymer, quansen paper making agent can make the positive molecule become strong positive, thus greatly increasing the charge adsorption capacity.

l Drainage

Retention and drainage aids is a chemical added to improve the water drainage and dehydration rate of wet paper from the net.The drainage aid can flocculate the fine fiber on the surface of the fiber, reduce the blockage of the wet paper hole and increase the permeability. Drainage and retention are linked in promoting the flocculation of dispersions.So there are a lot of similarities in terms of performance.The main types of retention and drainage aids are polyethylenimine, polyacrylamide, polyamine amide, cationic ethylene series of polymers.The primary filter aid is polyethylenimine.Later, due to the reduction of polyacrylamide price and the development of various modified polyacrylamide, PAM gradually became the main application.

The uniform molecular weight and molecular structure of quansen additive bring about the uniform flocculation. The distribution of these flocculations on the paper network is obviously different from that of non-use of macromolecular flocculant or other products with uneven molecular weight.

When no macromolecular flocculant is used, the size of the slurry fibers and fillers is different, and automatic spatial distribution is carried out on the paper network due to the effect of gravity. Small substances are filled between the particles through large material gaps, forming dense barrier layer, and seriously reducing the indrainage rate of water.

The flocculation can prevent the particles from being compactly arranged by the size of the material, and the small substances used to fill the gap can be flocculated, which can effectively free up the indrainage space of water and accelerate the drainage rate.However, the non-uniform flocculation, especially the flocculation caused by the products with seriously different molecular weight, has a significant difference in grain size. The small flocculation can also enter the gap between the large flocculation and reduce the water indrainage rate.