Kemira develop approach to using ASA sizing on wood-free machines with shoe presses - not possible before

Kemira has found a way to use ASA (click here to see article) on fast, modern paper machines used for producing woodfree uncoated paper equipped with one or two single or double-shoe presses. The rubber transfer belts that are an integral part of these shoe presses have given problems and machines of this type cannot use conventional ASA sizing, as large quantities of sizing residues build up on the belts, causing deposit problems. The new advances made by Kemira, allow ASA sizing to be used with these machines.

The highly hydrophobic material used on the surface of belts acts as a ‘magnet’ for ASA molecules. Creating a strongly hydrophilic surface film on the belt eliminates this attraction. The Kemira solution makes use of existing paper machine equipment, which keeps investment costs low.

The surface of the belt is 'neutralised' by spraying it with a highly cationic chemical, which dissolves in water and is sprayed onto the belt using low-pressure jets that 'lubricate' the belt.

Using this approach, the rate at which the deposits develop is slowed, allowing the belt’s mechanical cleaning system, based on high-pressure jets and doctors to clean more effectively.

Any comments from those that have experienced this new system would be more than welcomed.