A novel polyvinylamine drainage and strength technology for packaging grades

Current end-user strength requirements for packaging and board grades are progressively becoming more demanding to meet globally. Primarily this is due to the continuous deterioration of recycled furnish quality. Furthermore, the global industrial trend towards cost savings in productivity can only be accomplished by improving drainage and retention efficiency while at the same time light weighting. These trends confront the papermaker with a growing need for lower basis weights, higher filler levels, increased stiffness, burst and SCT. Newly developed polyvinylamine (PVAm) technology by Kemira is a solution to achieve simultaneously these challenges at lower application dosage rates. This allows the board manufacturer to overcome the limitations of the deteriorating recycled furnish quality and better cost efficiency. The novel PVAm technology, with an optimized molecular weight and charge density, has demonstrated to be a superior dry strength and drainage agent compared with the current market technology. The higher drainage and retention performances were measured by using a single-pass drainage test. Furthermore, the results of a filtrate recirculating method to simulate the short loop of a paper machine proved that the polyvinylamines have an eminent improvement in drainage. This technique assists us to explore the actual drainage performances of polyvinylamines through the explanation of the drainage mechanisms. The results have shown that an optimal low charge of PVAm brings the most effective performances in drainage and retention due to the contributions of the bridging and charge neutralization-mechanisms. The results of liner and fluting sheets produced on a pilot paper machine showed that PVAm based polymers have also real benefits for the SCT and burst strength. The applicability of low charged PVAm was concluded to be a superior drainage and dry strength agent with liner and fluting OCC furnish. This paper reviews Kemira's novel PVAm based technology by introducing a tailor-made polyvinylamine polymer to fit customers' needs in respect of process conditions.