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  Process for improving dry strength and drainage of paper and paperboardUSPTO Application #: 20060162886Title: Process for improving dry strength and drainage of paper and paperboard Abstract: A process is provided of providing glyoxylated polymer additives to a paper making process which brings about improvements in drainage properties of a cellulosic pulp material along with the ability to increase the dry strength of a resulting paper product. The process uses concentrated glyoxal to generate a working solution of a glyoxylated polymer additive which can be generated on site in a paper mill and used within a 24 to 48 hour interval. The ability to glyoxylate polymers in a working solution concentration provides for a more active additive and which can be supplied in a more economical fashion than conventional glyoxylated polymers. (end of abstract) Agent: J. Bennett Mullinax, LLC - Greenville, SC, US Inventors: William E. Smith, Jeffrey J. Meier USPTO Applicaton #: 20060162886 - Class: 162166000 (USPTO) Related Patent Categories: Paper Making And Fiber Liberation, Processes And Products, Non-fiber Additive, Synthetic Resin, Amine- Or Amide-aldehyde The Patent Description & Claims data below is from USPTO Patent Application 20060162886. Brief Patent Description - Full Patent Description - Patent Application Claims
RELATED APPLICATIONS [0001] This application claims the benefit of U.S. Provisional Application Ser. No. 60/646,341, filed on Jan. 24, 2005, and which is incorporated herein by reference. FIELD OF THE INVENTION [0002] This invention is directed towards the manufacturing process of paper, paperboard, corrugated products, and other fiber-containing products such as gypsum board/drywall and fiber-based backing for vinyl flooring. This invention further relates to additives used in the wet end of a papermaking process to confer dry strength to the resulting product. An additional aspect of one aspect of the invention is a process which improves manufacturing efficiency by promoting increased drainage during fiber processing. BACKGROUND OF THE INVENTION [0003] Within the papermaking art, it is known to add cationic starches during fiber processing/manipulation so as to achieve an improved retention of cellulosic fines, filler, and/or pigment within the fiber product and to also bring about an improved dry strength in the resulting paper. [0004] Glyoxal is another additive which is frequently combined with a polyacrylamide polymer for incorporation into the wet end of a papermaking process. A glyoxylated resin additive is frequently used to obtain increased internal bond strength, greater dry tensile strength, improved modulus of elasticity, and improvements in sizing effectiveness. [0005] Further, since the glyoxylated polymer additives may have cationic charges, the amount of cationic charge can be controlled so as to provide desired drainage and retention properties to the paper. Proper pH regulation avoids problems associated with excessive cationic charges such as flocculation of the fibers. [0006] Heretofore, it has been the custom and practice within the papermaking industry to use bulk supplies of a low solids content of glyoxylated polymers having about 6% to about 11% solids. However, glyoxylated polymer solutions, even at the commonly used concentration levels, suffer a noticeable loss of efficiency following three to four weeks of storage. Further, if not used within a narrow time interval, the glyoxylated polymer will gel. Once gelling occurs, the glyoxylated polymer is no longer usable, and the equipment affected by the gelled glyoxylated polymer must be cleaned and reconditioned. In addition, the gel time of glyoxylated compositions is dependent upon ambient temperature. Accordingly, glyoxylated polymer degradation and gelling occurs more rapidly in warmer climates. [0007] Since the traditional glyoxylated polymers employed within the papermaking industry have a limited storage life, it is common for the stored glyoxylated additives to be used for paper and paperboard products which do not require the higher strength parameters normally associated with the use of the strength additives. In other words, glyoxylated additives are frequently incorporated into products merely as a way of using up stored additive inventory before unacceptable gelling occurs. [0008] Accordingly, there remains room for improvement and variation within the art. SUMMARY OF THE INVENTION [0009] It is one aspect of at least one of the present embodiments to provide for a paper manufacturing process in which a high solids content glyoxylated additive can be mixed into a cellulosic pulp material by the incorporation of glyoxal and glyoxal-polymer reaction products into the cellulose pulp prior to formation of the paper product. Accordingly, a glyoxylated product may be added to an aqueous suspension of paper stock while the paper stock is in the head box recirculation loop, in the thick stock chest, the hydropulper, or at other points in the process prior to or after formation of a sheet. An example of the latter would be the spraying of a gloxylated polymer solution between the plies of a multi-ply sheet. [0010] It is yet another aspect of at least one embodiment of the present invention to provide for a process of using stock solutions of glyoxal and polymer at about a 25% to about a 40% solids range which can be used on site to produce a diluted working solution of glyoxylated polymer at about a 4% to about a 6% solids concentration. The 4% to 6% solids solution is thereafter metered into a papermaking process as a glyoxylated polyacrylamide polymer solution, for example. [0011] It is a further aspect of at least one embodiment of the present invention to provide for a process for introducing glyoxal to various reactive polymers, starches, gums, etc., to produce a cross-linked dry strength resin having excellent drainage properties and which can be applied in situ in a paper mill operation. [0012] It is a further aspect of at least one embodiment of the present invention to employ a metering system for a glyoxal stock solution and a base polymer to produce a freshly prepared glyoxylated polymer working solution of between about 4% to about 6% solids concentration. The working solution is useful for incorporation into a thick paper stock solution having between about 2% to about 5% solids and thereby achieve an increase in dry strength of the resulting paper product. The working solution can also be used to improve drainage properties in a thin paper stock having solids of less than about 1%. [0013] It is a further aspect of at least one embodiment of the present invention to provide for a working solution of a glyoxylated additive in a papermaking process which reduces the tendency of the reaction product to form undesired gels. [0014] It is yet another aspect of at least one embodiment of the present invention to provide for a process of introducing a glyoxylated additive, the proportion of glyoxal to polymer of which is varied, depending upon monitored production goals, such as sheet strength, stock drainage and drying rates, white water quality, and process variables which may include water properties, stock pH, fiber quality, fines content, and the type and amount of additional additives used in the paper making process. [0015] It is yet a further aspect of at least one embodiment of the present invention to provide for an effective sulfide, or other sulfur compound, scavenging amount of free glyoxal in a working solution of a glyoxal additive which serves as a sulfide scavenger within a fiber furnish. [0016] These and other features, aspects, and advantages of the present invention will become better understood with reference to the following description and appended claims. BRIEF DESCRIPTION OF THE DRAWINGS [0017] A fully enabling disclosure of the present invention, including the best mode thereof to one of ordinary skill in the art, is set forth more particularly in the remainder of the specification, including reference to the accompanying drawings. [0018] The FIGURE is a schematic view of a process of incorporating a high solid content glyoxylated polymer into the wet end of a papermaking process. DESCRIPTION OF THE PREFERRED EMBODIMENT Continue reading... 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