Organic compounds -- part of the class 532-570 series – Organic compounds – Carbohydrates or derivatives
Reexamination Certificate
2000-08-10
2003-07-01
Wilson, James O. (Department: 1623)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carbohydrates or derivatives
C536S102000, C536S105000, C536S121000, C536S123000, C536S123100, C536S124000, C536S001110, C536S056000, C536S114000
Reexamination Certificate
active
06586588
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to the preparation of polysaccharide aldehydes using selective oxidation conditions. More particularly, this invention involves the preparation of polysaccharide aldehyde derivatives using nitroxyl radical mediated aqueous oxidation with a limited amount of oxidant and defined reaction conditions to provide derivatives with maximum effective aldehyde and minimal carboxylic acid content. This invention further involves the use of these selectively prepared polysaccharide aldehydes as strength additives in papermaking.
The term “paper” as used herein, includes sheet-like masses and molded products made from fibrous cellulosic material which may be derived from natural sources, synthetics such as polyamides, polyesters, rayon and polyacrylic resins as well as from mineral fibers such as asbestos and glass. In addition, paper made from combinations of cellulosic and synthetic materials are applicable herein. Paperboard is also included within the broad term “paper”.
The preparation of aldehyde containing polysaccharides and the use of such aldehyde derivatives as wet and dry strength additives in the paper industry is well known. Oxidative and non-oxidative methods have been used to introduce aldehyde groups into polysaccharides such as starches, gums and celluloses. Oxidative methods are well known for introducing aldehyde groups into polysaccharides such as starch. These oxidative methods have included: a) treatment of starch with alkali metal bromite or hypobromite under carefully controlled conditions as disclosed in U.S. Pat. No. 3,553,193 issued Jan. 5, 1971 to D. H. Leroy et al.; b) oxidizing a carbohydrate with an alkali metal ferrate as shown in U.S. Pat. No. 3,632,802 issued Jan. 4, 1972 to J. N. BeMiller; c) enzymatically oxidizing hydroxypropyl galactoglycoside starch ethers or ethyl galactoglycoside starch ethers with galactose oxidase as disclosed in U.S. Pat. No. 4,663,448 issued May 5, 1987 to C. W. Chiu; and d) treatment with periodic acid or periodates as disclosed in U.S. Pat. No. 3,096,969 issued to J. E. Slager on Apr. 23, 1963 which shows the preparation of dialdehyde polysaccharide using periodic acid and U.S. Pat. No. 3,062,652 issued on Nov. 6, 1962 to R. A. Jeffreys et al. which shows the preparation of dialdehyde gums using periodate or periodic acid.
Oxidative methods often cause degradation of the polysaccharide and the formation of excess carboxyl groups. Excess carboxyl groups undesirably reduces the degree of aldehyde substitution and negatively affects the cationic/anionic balance of the functional groups when using a cationic polysaccharide base in papermaking applications.
The use of nitroxyl radicals and nitrosonium salts in organic chemistry as an oxidative route to access aldehydes and carboxylic acids from primary and secondary alcohols is disclosed in an article entitled “Organic Nitrosonium Salts As Oxidants in Organic Chemistry” by J. M. Bobbitt and C. L. Flores, in
Heterocycles
, Vol. 27, No. 2, 1988, pp. 509-533. Recently, application of this chemistry was extended to the selective oxidation of primary alcohols in various carbohydrates to carboxylic acids in an article entitled “Selective Oxidation of Primary Alcohols Mediated by Nitroxyl Radical in Aqueous Solution. Kinetics and Mechanism” by A. E. J. de Nooy and A. C. Bessemer, in
Tetrahedron
, Vol. 51, No. 29, 1995, pp. 8023-8032. Patent publication WO 95/07303 dated Mar. 16, 1995 further discloses the use of this technology where carbohydrates having a primary hydroxyl group are oxidized under aqueous conditions to form products having a high content of greater than 90% carboxyl groups. This art involving the oxidation of primary alcohols generally describes the preparation of polyglucuronic acids with high carboxylic acid content. Similarly, the process of oxidation has been used to prepare various polysaccharides with high carboxyl content as described in “Oxidation of Primary Alcohol Groups of Naturally Occurring Polysaccharides with 2,2,6,6-Tetramethyl-1-piperidine Oxoammonium Ion” by P. S. Chang and J. F. Robyt in
J. Carbohydrate Chemistry
, 15(7), 1996, pp. 819-830. It should be noted that in some applications high carboxylic content is undesirable.
A recent patent publication, WO 99/23240 dated May 14, 1999 discloses a method for producing oxidized starch using an oxoammonium ion producing reagent in the presence of an enzyme oxidizing agent. Polysaccharide aldehydes may also be prepared by non-oxidative methods which typically involve the reaction of a polysaccharide with an aldehyde containing reagent. For example, U.S. Pat. No. 4,675,394 issued to D. Solarek et al. on Jun. 23, 1987 discloses a non-oxidative method wherein polysaccharide is reacted with a derivatizing acetal reagent in the presence of alkali to provide the stable acetal polysaccharide. The general disadvantage of these non-oxidative approaches is that they often require an extra conversion step to the aldehyde. For example, the polysaccharide acetals need to be cooked or pre-treated under acidic conditions to form the aldehyde just prior to its use.
What is desired is a direct and selective oxidation route to polysaccharide aldehyde derivatives wherein the aldehydes are formed at maximum effective levels and carboxylic acid levels are minimized making such aldehyde derivatives especially useful as wet, temporary wet and dry strength additives for paper.
SUMMARY OF THE INVENTION
Now it has been found that polysaccharide aldehydes can be selectively prepared under defined oxidation conditions using a nitroxyl radical mediated aqueous oxidation procedure to provide derivatives with maximum effective aldehyde and minimal carboxylic acid content.
More particularly, this invention involves the oxidation of a polysaccharide in an aqueous solution with an oxidant having an equivalent oxidizing power of up to 14.18 g active chlorine per mole of polysaccharideanhydrosugar unit (“ASU”) and a mediating amount of nitroxyl radical, the reaction being carried out at a temperature of at or below about 15° C. and a pH of from about 8.0 to 10.5 and the resulting product having up to about 15 mole % of C-6 aldehyde groups per mole of polysaccharide ASU and minimal carboxylic acid content. A polysaccharide ASU is defined to be the monosaccharide residues from which linear or branched polysaccharides can be seen to be constructed by a series of condensation reactions.
The polysaccharide aldehyde derivatives are useful in conventional applications where water-soluble or water-swellable polysaccharide derivatives are useful, for example, as coatings, adhesives and paper additives. The cationic aldehyde containing derivatives are particularly useful as wet, temporary wet and dry strength additives for all paper types including liner board.
DETAILED DESCRIPTION OF THE INVENTION
This invention involves the selective oxidation of polysaccharides in an aqueous system using a limited amount of oxidant with a nitroxyl radical mediator under defined conditions. The prepared products are highly selectively oxidized polysaccharides where there is a high level of C-6 aldehyde functionality with minimal carboxylic acid and are particularly suitable as wet, temporary wet and dry strength paper additives.
When the polysaccharide is starch, the starch base material useful in this invention may be any of several starches, native or modified. Such starches include those derived from any plant source including, corn, potato, sweet potato, wheat, rice, tapioca, waxy maize, sago, sorghum and high amylose starch such as high amylose corn, i.e., starch having at least 45% by weight of amylose content. Starch flours may also be used as a starch source. Also included are the conversion products derived from any of the former bases including, for example, dextrins prepared by the hydrolytic action of acid and/or heat; fluidity or thin-boiling starches prepared by enzyme conversion or mild acid hydrolysis; and derivatized and crosslinked starches.
The starch may be modified with cationic, anionic, amph
Cimecioglu A. Levent
Thomaides John S.
LeCroy, Esq. David P.
National Starch and Chemical Investment Holding Corporation
White Everett
Wilson James O.
LandOfFree
Polysaccharide aldehydes prepared by oxidation method and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Polysaccharide aldehydes prepared by oxidation method and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Polysaccharide aldehydes prepared by oxidation method and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3059029