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AssigneeNone recorded
InventorsRussell J. Kulick, Elieth W. Harris, Dan S. Honig
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A method for making paper is disclosed. The method comprising adding to a furnish comprising cellulosic, paper-making fibers (i) from about 0.05 to about 20 pounds per ton, based upon the dry weight of the furnish solids, of an ionic, organic, crosslinked polymeric microbead with a diameter of less than about 500 nm, and (ii) from about 0.05 to about 20 pounds per ton, same basis, of a polymeric material, containing vinylamine recurring units. In addition to the compositions described above, additives such as organic ionic, polysaccharides (e.g., a starch), may also be combined with the liquid system to facilitate drainage and retention.
A method for making a filled or unfilled paper which comprises adding to an aqueous paper-making furnish (i) from about 0.05 to about 20 pounds per ton, based on the dry weight of the furnish solids, of an ionic, organic, cross-linked polymeric microbead and (ii) from about 0.05 to about 20 pounds per ton, same basis, of a polymeric material, or salt or quaternary thereof, having the formula
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Additives of definite length or shape: being spherical, e.g. microcapsules, beads
Polysaccharides: starch
Obtained by reactions only involving carbon-to-carbon unsaturated bonds: containing ionic groups
Nitrogen-containing groups: comprising tertiary amine or being at least partially quaternised
Term end not estimated
The present invention relates generally to compositions and methods for providing improved liquid-solid separation performance in papermaking processes. More particularly the invention relates to the addition of vinylamine polymers and ionically charged organic polymer microbeads to papermaking systems comprising liquid dispersions of cellulosic fibers for improving drainage, retention and formation in such systems.
Papermaking processes require treatment of a system comprising a liquid dispersion of solid particles for separating the solids therefrom. Fast drainage and greater retention of fines contribute to lower costs in papermaking and thus improvements in this area are always being sought. Improvements in formation are likewise desired as-such improvements result in a better product. One method for improving these properties, which was first practiced during the 1980's, involves the use of colloidal silica and bentonite. The improved drainage offered with the use of these materials, i.e., as indicated by increasing speed and efficiency with greater retention of fines, provides significant cost savings over the prior art techniques.
U.S. Pat. Nos. 4,385,165 and 4,388,150 describe a two-component binder system comprising a cationic starch and an anionic, colloidal silicic acid sol which acts as a retention aid when combined with cellulose fibers in a paper-making stock. Finnish published specification Nos. 67,735 and 67,736 disclose cationic polymer retention agent compounds comprising cationic starch and polyacrylamide. These materials are described by the subject references as being useful when combined with an anionic silica in improving sizing.
A simulated alkaline fine paper furnish of 80/20 ratio oz pulp solids (70/30 hardwood/softwood bleached Kraft pulp) to CaCO3 filler is used in this drainage test. It also contains 250 ppm-of SO4 added as Na2SO4, 100 ppm of HCO3 added as NaHCO3, 50 ppm of Ca added as CaCl3 and 5 pounds of cationic potato starch. The furnish pH is 8.0. To this furnish are added the additives in Table 1. 1 TABLE I Additive 10 × Drainage-sec. 1) .33 lb. PVA-a 103 .66 lb. PVA-a 85 .99 lb. PVA-a 74 2) .33 lb. PVA-a 57 2.0 lb. Microbead A 3) .66 lb. PVA-a 40 2.0 lb. Microbead A 4) .99 lb. PVA-a 22 2.0 lb. Microbead A 5) .33 lb. PVA-b 102 .66 lb. PVA-b 85 .99 lb. PVA-b 82 6) .33 lb. PVA-b 42 2.0 lb. Microbead A 7) .66 lb PVA-b 27 2.0 lb Microbead A 8) .99 lb PVA-b 21 2.0 lb Microbead
This example clearly shows the enhanced drainage achieved using the process of the present invention, especially as shown in Tests 4 and 8.
The procedure of Example 1 is followed with the following results. In this case, the furnish includes 10 pouunds of a cationic potato starch. 2 10 × Drainage-sec. Additive with 2 lbs Additive-lbs. Microbead A .33 .66 .99 1.32 PEI # 1 47 42 42 — PEI # 2 51 49 42 — PAA · HCl (40% sol.) 69 62 60 59 PVA-b 47 30 21 17 PVA-a 61 38 27 21 The PEI's and PAA are tested on an active solids basis. PAA = polyallylamine