The Application of PolyDADMAC in Papermaking

As a kind of water-soluble cationic polymer, PolyDADMAC has the advantages of the high density of positive charges, good water solubility, controllable molecular weight, high efficiency, no toxic, and low cost, therefore it is widely used in oil drilling, paper making, mining, textile printing and dyeing, daily-use chemical industry, sterilization, metal anti-corrosion, water treatment, and other fields. 

PolyDADMAC is mainly used as the standard titrant, anionic capture, and flocculant in the papermaking industry, and it can also be used in the production of conductive paper. 

1. Used as a standard titrant 

With medium molecular weight and charge density, PolyDADMAC has become the standard cationic polymer in general use. However, it can only be applied when the ionic strength of the solution is low and the charge density of the measured polyelectrolyte is not too low. When the existing metal ion concentration exceeds a certain range, it is advisable to use a cationic polymer labeled with a chromogenic group for titration.

2. Used as an anionic capture

The closed circulation of the whitewater system and the use of bleached wheat straw pulp with high positive charge demand in paper mill increase the amount of dissolved and suspended interferents in paper materials, which usually reduces the effectiveness of additives. Thus, adding PolyDADMAC, a chemical auxiliary (anion extractor) that neutralizes charges, before other chemical additives can neutralize the dissolved and suspended interferers. 

3. Used as a flocculant 

PolyDADMAC is a kind of non-toxic cationic polymer flocculant with good performance, which plays a very great role in papermaking sewage treatment. Bridging adsorption is produced between PolyDADMAC and suspended colloidal particles to achieve the flocculation effect.

4. Used in the conductive paper 

Usually, the most suitable surface resistance of conductive paper is 1060 Ω·cm. Either too high or too low surface resistance will cause a phantom latent image, video overlap, and other problems, resulting in poor quality copies. The commonly used conductive substance is PolyDADMAC, and the diallyl monomer plays the cyclization role during polymerization to form a pyrrole ring. The polymer solution can be applied to the paper web by coating, dip coating, brush coating, or wet-end addition.