METHOD AND PRODUCTS FOR SIZING PAPER AND SIMILAR MATERIALS

摘要

Method of sizing paper and, in particular, paper made under neutral to alkaline conditions at least as high as 10.5. The papermaking stock is first treated with a polycationic material to provide sizing receptive sites uniformly distributed over the fiber surface. The presence of the anchoring points is critical to the later redistribution of the sizing material in the dryer section of the paper machine. The sizing material is then added to the slurry. This is then brought down onto the fibers by addition of a small amount of a size precipitant such as alum. The sizing molecule should have a hydrophilic portion with two hetero atoms forming a bidentate analog structure. This must have a pK in water of 6.0 or higher and a vapor pressure preferably at least 0.0006 mm Hg at 60 DEG C. The polycationic material provides anchoring/orienting sites on the fiber to which the small globules of sizing attach when the emulsion is broken by the precipitant. Sizing will develop in the dryer section of the paper machine, presumably by vapor phase redistribution of sizing from the attached globules to unfilled sites where an anchoring point is present. Alkyl and alkenyl substituted catechols, beta-diones, hydrozamic acids and imides are among the new classes of sizing materials disclosed.