Paper making and fiber liberation – Processes and products – Non-fiber additive
Reexamination Certificate
1997-12-31
2001-01-30
Fiorilla, Christopher A. (Department: 1731)
Paper making and fiber liberation
Processes and products
Non-fiber additive
C162S164300, C162S164400, C162S164600, C162S164700, C162S166000, C162S178000, C428S409000
Reexamination Certificate
active
06179962
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a new process for improving paper strength and more particularly it relates to the use of combinations of oxidized galactose containing polymer and cationic polymers in the papermaking process.
2. Description of the Prior Art
The product of the oxidation of aqueous solutions of guar gum and other galactose bearing polysaccharides using galactose oxidase enzyme was disclosed by F. J. Germino in U.S. Pat. No. 3,297,604. The aldehyde bearing oxidized products are separated by precipitation from the aqueous solutions used for the enzyme reactions. Germino disclosed the use of the oxidized products in the manufacture of paper. The aldehyde bearing oxidized products were disclosed to be also suitable for use to crosslink polyamino polymers, polyhdroxy polymers, and proteins.
C. W. Chiu, et. al., U.S. Pat. No. 5,554,745, discloses (1) the preparation of cationic galactose containing polysaccharides and (2) the enzymatic oxidation in aqueous solution of the cationic galactose containing polysaccharides with galactose oxidase. The oxidized cationic polysaccharides are disclosed to improve the strength characteristics of paper.
SUMMARY OF THE INVENTION
According to the present invention, there is provided a process for making paper having improved strength characteristics by providing pulp and adding thereto (1) cationic polymer and (2) oxidized galactose type of alcohol configuration containing polymer wherein the alcohol has been oxidized to aldehyde, and sheeting and drying the paper, provided that when the oxidized galactose type of alcohol configuration containing polymer is oxidized guar it is selected from the group consisting of oxidized neutral guar, oxidized anionic guar and oxidized amphoteric guar.
Further according to the present invention there are provided paper products having improved strength characteristics prepared by using the combination of cationic polymers and oxidized galactose type of alcohol configuration containing polymers.
DETAILED DESCRIPTION OF THE INVENTION
It has surprisingly been discovered that oxidized galactose type of alcohol configuration containing polymers such as neutral, anionic and/or amphoteric oxidized guar, in combination with water-soluble or water-dispersible cationic polymers give significant strength improvement over the unoxidized or oxidized guars alone.
The treatment of oxidizable galactose type of alcohol configuration containing polymer with galactose oxidase and catalase is the subject of companion application Ser. No. 09/001,789, filed Dec. 31, 1997, entitled “Oxidation in Solid State of Oxidizable Galactose Type Alcohol Configuration Containing Polymers” by R. L. Brady, R. T. Leiffried and T. T. Nguyen, the disclosure of which is hereby incorporated by reference.
The oxidizable galactose alcohol type of configuration can be described by the following chemical structures:
where;
R1=an alkyl group of the formula C(n)H(2n+1) where n=0-20;
z=0,1;
R2=a linking group composed of an alkylene, or an aromatic alkylene, or an alkylene ether, or an alkylene ester, or an alkylene amide, or an alkylene urethane diradical. Such linking groups have a total number of carbon from 2 to 20;
R3=—H, —OH, —OCH3, —OC2H5, —OC3H7, —OC4H9, —OOCR5 (where R5=alkyl radical of 1 to 5 carbons), —NH2, —NH—CO—R5;
and y=0,1.
The oxidizable galactose type of alcohol configuration containing polymers can be galactomannan gums or their ether derivatives, arabinogalactan gums or their ether derivatives, other gums or their ether derivatives, galactoglucomannan hemicelluloses or their ether derivatives and synthetically or enzymatically modified polymers. Preferred galactomannan gums are guar, locust bean, tara and fenugreek. Preferred arabinogalactan gums are arabic, larch and tragacanth gums. Preferred synthetically or enzymatically modified polymers are galactose deficient polysaccharides, polyacrylamides, polyacrylates, polyamides, polyvinyl alcohol, and polyvinyl acetate. Most preferred such polymers are starch and polyacrylates. The phrase “galactose deficient” as used in the present application means that the oxidizable galactose type of alcohol configuration containing polymer it refers to contains less than 20% of oxidizable galactose alcohol configuration based on the weight of the oxidizable galactose type of alcohol configuration containing polymer. Preferred other gums are carubin, lichenan, tamarind and potato galactan. Most preferred oxidizable galactose type of alcohol configuration containing polymers are guar gum and its ether derivatives such as anionic, amphoteric, hydroxypropyl, dihydroxypropyl and hydroxyethyl guar.
Synthetically or enzymatically modified polymers can be obtained by transferring an oxidizable galactose alcohol type of configuration to polymers. Glycosyl transferases or hydrolases can be used to transfer galactose from lactose unto e.g., polysaccharides to provide useful polymers for oxidation. Synthetic methods can also be used to attach the oxidizable galactose alcohol type of configuration. By these methods, other oxidizable saccharides such as gulose, fructose, sorbose, mannose, talose, xylose and ribose may be attached to polymers providing candidates for oxidation.
The oxidized galactose type of alcohol configuration containing polymer component of the present invention has at least about 5 mole % of its oxidizable galactose type of alcohol configuration oxidized to aldehyde. Preferably, at least about 25 mole % and most preferably at least about 50 mole % of such alcohol has been oxidized to aldehyde. The oxidizable galactose type of alcohol configuration containing polymer used for oxidation can range over a wide molecular weight range. It can be high molecular weight, or alternatively it can be a depolymerized (reduced viscosity) polymer. Generally, the lower limit of the weight average molecular weight of the oxidizable galactose type of alcohol configuration containing polymer can be about 5,000. The upper limit of the weight average molecular weight of the oxidizable galactose type of alcohol configuration containing polymer can be about 5,000,000. Preferably, the molecular weight range as indicated by room temperature Brookfield viscosity is at least about 15 cps at 2 weight percent solution in water, most preferably, at least about 100 cps at 1 weight percent solution in water. Preferably, the room temperature Brookfield viscosity can be up to about 10,000 cps, and most preferably up to about 6,000 cps. at 1 weight percent solution in water (Measured in Brookfield LVT viscometer with small sample adapter, 25° C., spindle 31, speed 3 rpm).
Oxidized guar is preferred as the oxidized galactose type of alcohol configuration containing polymer for use in the present invention. The present application refers to oxidized guar specifically in certain instances, however, the person of ordinary skill in art will recognize that these teachings apply to the oxidized galactose type of alcohol configuration containing polymer in general.
The oxidizable galactose type of alcohol configuration containing polymer can be oxidized in solid form, in slurry form or in solution. The oxidation can be carried out chemically or enzymatically by galactose oxidase. Preferably neutral or anionic or amphoeteric guar that has been oxidized by galactose oxidase and catalase is used in the present invention. Galactose oxidase can be applied to solid, slurry, or solution forms of guar products: e.g., shredded, powder, flake, and pellet forms of neutral, anionic or amphoteric guar. Guar derivatives, such as those containing hydroxypropyl groups can also be used.
Galactose oxidase (EC 1.1.3.9) is a copper oxidase which converts the oxidizable galactose type of alcohol configuration to the corresponding aldehyde group (thus producing oxidized galactose) by reducing oxygen to hydrogen peroxide. The copper must be in the correct oxidation state (Cu
2+
) to perform this oxidation and the copper ion must be r
Brady Richard Lee
Leibfried, Sr. Raymond Thomas
Nguyen Tuyen Thanh
Fiorilla Christopher A.
Greenblum & Bernstein P.L.C.
Hercules Incorporated
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