Factors influencing the treatment of paper with fluorochemicals for oil repellency

The objectives of this work were to understand why fluorochemicals, added to retard solvent or grease penetration, are more effective in wood-free papers than in mechanical pulp based papers. Newsprint required about ten times more fluorochemical than did Whatman #42 filter paper to achieve solvent resistance. Based on the result of kit tests, contact angle measurements, and X-ray photoelectron spectroscopy using both paper and regenerated cellulose films, it was concluded that about 40% of the added fluorochemical demand of newsprint - compared with filter paper - was due to the higher specific surface of newsprint. The remaining 60% was due to interference by solvent-extractable material (i.e., pitch). The negative effects of pitch could be partially circumvented by using hydrophobically modified starch in conjunction with fluorochemical. Application: The amount of fluorochemical surface application required to obtain solvent-resistant newsprint depends on the specific surface area and pitch content of the paper. Hydrophobic extractives appear to interfere with the uniform spreading of fluorochemical.