The Usage of The Polyacrylamide in The Paper Making
The anionic polyacrylamide is mainly used as the flocculant. For the suspended particles, the coarse, the high concentration and the particles with the positive charges, and the waste water with the PH value as neutral or alkaline, the anionic polyacrylamide can accelerate the settlement of the particles suspending in the water with the obvious effects in speeding up the solution clarification and in promoting the filtering, because the anionic polyacrylamide has a certain amount of the polar medium in its molecular chain which can absorb the suspending particles, bridge the particles and make the bridged particles to be formed as the large flocs. These kinds of products are widely used in the treatment of the waste water and the water liquid in the chemical industry, in the treatment of the municipal sewage, in the tap water industry, in the purification of the high turbidity water, and they are also widely used in the water treatment of various industries, such as the coal washing, the mineral dressing, the metallurgy, the iron and steel industry, the zinc and aluminum industry and the electronic industry etc.
In the above mentioned applications of the anionic polyacrylamide, different flocculating agents have different functions. The polyacrylamide PAM worked as the paper strengthening agent and the dispersing agent in the paper making from the recycled papers, in order to keep the strength of the paper tensile, to keep the good performance of the paper products, and also to meet the need of the modern offset printing, you can use the cationic polyacrylamide (CPAM) paper reinforcing agent, Its molecular length provides a good absorption performance and the bond position for the combination with the chlorine, which makes the fibers combination reinforced, therefore, it figures a variety of functions, such as the enhancement, the retention and the filtration etc, especially the tearing index is increased which can effectively improve the paper strength. The polyacrylamide can be used to make the heat resistant and waterproof paper as the reinforced agent. For example, use the fatty acid sizing agent 0.5, the PAM type paper strengthening agent 0.2, the aluminum sulfate 1.0 and the epoxy reinforced agent 0.7, add them into the paper making chemical pulp, make the paper product soaked in 200C for one hour, the tearing strength of the paper product can reach up to 183g, and with the good printing performance. Add the acrylamide, the acrylic acid and the copolymer of the acrylic acid hydroxyl ethylester and the cationic cassava starch graft into the Canadian standard beating pulp of 500ML, and add Al2(SO4)3, make the quantitative 74.2g/m2 paper product, the tearing strength is 8950g, the strength of the middle layer is 148g, the tear factor is 135. When the production speed 800m/min, the concentration 0.6%, the paper ash content 20%, the introduction of the PAM retention agent can reach 80% first processing retention and 50% first pass ash retention.
When the polyacrylamide is used as the paper dispersing agent, it can improve the sheet formation.
The polyacrylamide PAM could be used as the retention acid.
The unit retention agent, American company BAYER model RETAMINOL C0.1. Its composition is CPAM (the cationic polyacrylamide), the general adding is 0.05% ~ 0.3% with the appropriate concentration is 0.1% ~ 1%.
The dual retention agent: the composition is PEI + PAM, the general adding is 0.2% ~ 1.0% with the appropriate concentration is 0.5% ~ 1.5%. The adding method is to premix them up before adding.
The flocculation and retention agent series product from Sweden Akzo – Nnobel company is mainly composed of CPAM and the colloidal silicon. They are suitable for the low weight coated paper, including the recycling pulp system. In the micro particle flocculation system, firstly add the CPAM to form the large flocs, under the action of the shear stress, the large flocs are dispersed into the small flocs, then add the negative colloid silicon particles, the tiny colloid silicon particles can react with the small flocs, and combine into a more compact fine flocculation system with better dehydration. Thus, it can achieve the higher retention, the better uniformity and the better filtration performance.
To use the cationic PAM as the retention agent, the retention rate is 98%. The tiny fiber and the lignin in the pulp has better combination with the cationic polyacrylanmide than the anionic polyacrylamide, the cationic polyacrylamide has strong effect on the retention efforts. Modify the PAM with the resin gum, the gelatin and the titanium dioxide, it could be used as the wet end additives.
The polyacrylamide can be used to improve the pulp dewatering performance. In the manufacturing process, the alum, the anionic type polyacrylamide and the cationic starch is used to improve the result of the retention and the dewatering performance.
To use the polyacrylamide in the printing coating based paper as the retention agent can improve the retention of the fillers and the fine fibers, can accelerate the dehydration speed, can settle the sewage and can reduce the pollution. So, it is important for the environment protection and the economic benefit improvement.