Weyerhaeuser Company Limited

Tiedeman, George T.

Gess, Jerome M.

Jerome M Gess

Terry N Adams

George T Tiedeman

David G Halley

Margot J Harding

Russell J Martz

Dennis E Petersen

Robert C Gaines

A drainage tester evaluates the reaction pattern of one or more reactions in a paper pulp furnish to predict behavior of the pulp on a paper line. The tester includes a mixing container in which an additive is mixed with the slurry under conditions that prolong the reactions in the container such that they take longer than the same reactions on a paper line. The mixer can also mimic the kinetic conditions (such as mixing by turbulence or passive diffusion) under which the additive is mixed with the furnish on the paper line. A test container has a screen bottom that separates furnish solid from slurry water by developing a pressure differential across the screen. An intermediate container is positioned between the mixing container and test container to provide a constant hydrostatic head on furnish transferred to the test container. A sensor above the screen in the test container monitors changes in the optical characteristics of a sheet formed on the screen to automatically determine the drainage time of the formed sheet. Sequential equal volume aliquots of furnish are withdrawn from the mixing container and sent to the test container at preselected time intervals after chemical additives are mixed with the furnish in the mixing container. Physical characteristics of the sheet, such as fines retention, drainage time and visual appearance, are recorded as a function of time from addition of additive to the mixing container. Behavior of the sheet on the paper line can be predicted in this manner to help an operator efficiently operate a paper machine system.

Evaluating furnish behavior

The invention is an apparatus and method for measuring drainage time of a papermaking stock suspension. The apparatus will automatically measure drainage times of a plurality of samples which will preferably be of differing basis weights. It consists of a sheet mold reservoir and dropleg which index against or away from a table having spaced apart sheet forming locations. Operation of the apparatus is determined by a programmable controller which causes stock to be automatically transferred to the sheet mold and the reservoir and dropleg to be automatically and appropriately positioned. After a sheet is formed the table automatically indexes to the next forming position where the cycle is repeated. The method involves plotting a series of at least three points to determine the slope of drainage time versus the basis weight of the sheets formed. This can be used as an indicator of the drainage characteristics of a stock of given basis weight on the forming section of a paper machine.

Apparatus for determining drainage time of papermaking stock

The invention is a 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.degree. 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 redistribtution of sizing from the attached globules to unfilled sites where an anchoring point is present. Alkyl and alkenyl substituted catechols, beta-diones, hydroxamic acids and imides are among the new classes of sizing materials disclosed.

Method and products for sizing paper and similar materials

The invention is a fibrous, cationic cellulose pulp product and the method for preparing it. A water suspension of cellulosic fiber is treated under alkaline conditions with a condensate of epichlorohydrin and dimethylamine. Up to 30 molar percent of the DMA may be replaced by a crosslinking agent such as ammonia or a lower aliphatic diamine. The process may be carried out at room or elevated temperatures. It is practical to add the condensate at one of the later alkaline stages of a bleaching process; e.g., an alkaline extraction or peroxide stage. This is most preferably done later than any chlorination or hypochlorite stages. The product shows greatly improved retention of acid and other anionic dyes. It also shows superior retention of some pigments and latices without the need for other cationic aids. In some cases a small amount of alum appears to have a synergistic retention effect with the cationic pulp product when used with titanium dioxide and certain anionic latices.

Cationic cellulose product and method for its preparation

The drainage quality of a pulp furnish slurry on a paper machine forming wire is predicted by the drainage tester of this invention by accounting for the effect of drainage through the paper sheet as it forms. The tester can distinguish between fast draining mechanical pulps and slower draining chemical pulps as well as predict the effects various additives will have on drainage. The apparatus includes a screen which separates furnish fibers from the slurry white water in response to a constant volume vacuum pump. Pressure differential as a function of time is recorded producing for any given furnish three distinctive points of inflection on the curve, including a first point of inflection which correlates with the wet line on a paper machine forming wire, second point of inflection which correlates with the dry line on the former and a third point of inflection which correlates with the maximum practicable removal of water from said pad by the typical former vacuum systems.

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Bellevue, WA, United States of America

Jerome M Gess