Ciba Specialty Chemicals Corporation

Raisio Chemicals Oy

Olof Malmstrom

Claes Zetter

Markku Nurminen

Kenneth Sundberg

Mari Niinikoski

A modified filler used in the making of paper or the like, preparation of the filler and its use. The modified filler comprises a filler known as such, e.g. Calcium carbonate, kaolin, talc, titanium dioxide, sodium silicate and aluminum trihydrate or their mixture, and a hydrophobic polymer made of polymerisable monomers, which is added to the filler as a polymer dispersion or a polymer solution.

Method for pretreatment of filler, modified filler with a hydrophobic polymer and use of the hydrophobic polymer

The present invention relates to a size composition of improving the water repellency of paper in papermaking by virtue of adding prior to web formation to the pulp slurry such a sizing dispersion that contains at least a ketene dimer compound as a hydrophobic sizing agent, and further contains colloidal starch in an amount which is at least 150% by weight of the hydrophobic sizing agent. The invention is particularly applicable for improving the water repellency of paper containing calcium carbonate as the filler.

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Abo, Finland

Olof Malmstrom