Reactive sizing agents

AKD sizing has been available for almost 50 years and was the first commercially available Synthetic, reactive sizing agent. AKD is a wax normally derived from a mixture of stearic (CIS) and palmitic (C16) fatty acids with a melting range between 42 C and 55°C, dependent on the fatty acid blend. However, there are... 

A useful side effect of the radiation and especially the plasma treatments is the cleaning of the fibre surface. Fibre lubricants, sizing agents, soil and other residuals are burned off This provides, combined with the creation of reactive radicals on the fibre surface, better wetting properties and a higher adhesion of coatings and laminations. Anti-felting finishes for wool are also achievable with plasma treatments. 

Rosin is a non-reaclive prodnct and is retained on the anionic fibre by either attaching itself to a cationic source in the case of rosin soap, or anionic rosin emulsion or by having a cationic surface charge. The main requirement is that it requires a source of aluminium species to form the actual sizing agent, aluminium rosinate. Rosin is normally modified with maleic anhydride or fumaric acid to increase its reactivity with aluminium species and improve its efficiency at higher pH. The method by which this aluminium species is formed and retained in the wet-end of the paper/ board machine differs between anionic and cationic rosin sizes. 

Cationic starch also has a major role in the emulsification and retention of highly reactive internal sizing agents. These emulsions have no charge other than the... 

Pormaldehycle is employed by the paper industry for impro -ing the wet" strength, water-resistance, shrirLk-resistance, gpease-resistance, etc., of paper, coated papers, and paper products. For these purposes formaldehyde is used both directly and in the form of reactive fonnaldeh Tie derivatives. In addition, formaldeh ide senes as a disinfectant and preservative in connection with some phases of paper manufacture. Less direct applications are found in the preparation of finishes sizing agents, etc. 

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