Advances in fatty acid based deinking chemistry

The sodium salts of fatty acids have been used in flotation deinking for thirty years and are still the dominant products for newsprint, especially in Europe. While there have been minor improvements in product form and composition there has been little major advance during this period. A new product recently introduced by Stephenson Recycling Chemicals offers the first significant advance in fatty acid based deinking chemicals. After twelve months product evaluation at many mills there is now a body of evidence to demonstrate its use at a significantly lower application rate compared with conventional fatty acid soaps. As well as the significant economic benefits achieved with lower application rates there are several technical advantages associated this new product, such as lower carryover of soap to the paper machine and consequently less deposit related problems. Improved paper machine runnability was reported at one mill trial. This new product is essentially a modified sodium soap of fatty acids and is classified as readily biodegradable. This is an impoflant attribute as the paper industry becomes more environmentally conscious. Environmental considerations have also led the move towards neutral deinking with anticipated lower effluent costs. Conventional fatty acid soaps used at lower pH conditions result in reduced brightness of deinked pulp. Recent small scale trials have shown this modified soap does not suffer this same loss of brightness when used at reduced pH conditions.