Organic compounds -- part of the class 532-570 series – Organic compounds – Carbohydrates or derivatives
Reexamination Certificate
2001-08-31
2004-03-23
Griffin, Steven P. (Department: 1731)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carbohydrates or derivatives
C536S104000, C536S105000, C162S175000, C162S164600, C162S168200, C106S208100, C106S208400, C527S309000
Reexamination Certificate
active
06710175
ABSTRACT:
FIELD OF INVENTION
The present invention relates to: (a) compositions suitable as additives in the paper industry; (b) to preferred modified starches as components of such compositions; (c) to processes for providing such compositions; (d) to paper or paper products comprising such compositions; and (e) to processes for manufacturing paper or paper-like products which include such compositions.
BACKGROUND
Starches are widely used in the paper industry as wet end additives, as size-press additives, as binders in coatings and as adhesives. Advantages of the use of starch in paper can, for example, be the increased strength of the resulting paper, improved runnability, enhanced drainage, reduced amount of pollutants released, increased hydrophobicity or increased optical properties such as brightness and color.
An important property in practically all grades of paper is the above referred to paper strength. Not only do most papers require a minimum strength for the ultimate purpose, the paper must also be strong enough to permit efficient handling in manufacture. Many measures for the strength of paper are known. For example, the tensile strength is the greatest longitudinal stress the paper can bear without tearing apart. Since some paper products are subjected to wetting by water in their normal use, the wet tensile strength becomes important. Other well-known tests used to test strength parameters in paper are, for example, the bursting test, or Mullen test.
Natural starches can be used in the manufacture of paper and can be chemically or enzymatically modified. Modified starches often used are, for example, cationic, anionic, oxidized and phosphated starches. Cationic starches are often used to provide retention at the wet end and reduce the amount of pollutants released. Oxidized starch is known to have good film-forming properties and is, therefore, a favored material for coating and surface sizing.
Several problems are attached to the use of starches in the paper industry. For example, unsatisfactory strength increases may occur due to the limited amount of neutral or negatively charged starch that can be added since the starch has little or no attraction to the negative charge of the pulp.
Conventionally used, cationic starch has an attraction to the pulp to provide good retention. However, when cationic starch is added in an amount of more than several percent, the retention of starch in the paper layer is reduced and the starch is released from the paper and enters into the waste water.
It is of continuing interest to find compositions conventionally and cost effectively usable for high starch inclusion in paper or paper like products.
U.S. Pat. No. 4,097,427 relates to a process of cationization of starch in an aqueous medium in the presence of alkali metal hydroxide, cationic water-soluble polymers containing quaternary ammonium groups and an agent. The agents used are, for example, ammonium persulfate, hydrogen peroxide, hypochlorites, ozone, and certain organic peroxides and hydroperoxides. The modified starches thus prepared are used as wet end additives in papermaking to improve the dry strength of the paper.
U.S. Pat. No. 4,146,515 (Nalco Chemical Corp) discloses paper and other cellulosic material sized with a cationic starch prepared by forming an aqueous slurry of an oxidized starch, adding cationizing agent to the slurry and heating the slurry in a continuous cooker. More specifically, U.S. Pat. No. 4,146,515 relates to a process for the preparation of a cationic starch by forming an aqueous slurry of a lightly oxidized starch by starch with hypochlorite, adding a cationizing agent to the slurry and then heating the slurry in a continuous cooker. Suitable cationizing agents are, quaternized ethylene dichloride ammonia reaction products, dially/dimethyl ammonium chloride polymers and quaternized polyethyleneimines.
U.S. Pat. No. 4,818,341 describes a process for producing paper and paperboard of high dry strength by adding a mixture of a polymer modified potato starch to the paper stock and dewatering the paper stock with sheet formation. The potato starch is modified by heating an aqueous slurry of 100 parts by weight of potato starch with 1 to 20 parts by weight of cationic polymer which contains units of diallyldimethylammonium chloride, vinylamine or N-vinylimidazoline, at a temperature above the gelatinization temperature of potato starch in the absence of any agent, polymerization initiator of alkali.
A similar process for the production of paper, paperboard and cardboard is described in U.S. Pat. No. 4,940,514. In this process an enzymatically digested starch having a viscosity of from 20 to 2,000 mPa.s (measured in 7.5% strength aqueous solution at 45° C.) is modified by treating with at least one of the cationic polymers specified above. The modified starch thus obtained is used as a wet end additive in the paper industry.
WO-A-98/31711 relates to a process for the production of starch which is modified with at least one cationic polymer. The polymer modified with starch is obtained by reacting an anionically modified starch with a cationic polymer or by reacting a natural starch or a non-anionically modified starch with a cationic polymer in the presence of an anionic modifier. Suitable anionic modifiers described include alpha-halogencarboxylic acids, inorganic or organic acids. The polymer modified starches are used as wet end additives in the production of paper and paper products.
U.S. Pat. No. 4,263,094 (BASF Wyandotte) discloses a cellulosic material such as paper or paperboard surface-sized with an aqueous dispersion of a combination of degraded starch derivative and a branched-chain, water dispersible polyester condensation product. The starch according to the invention is an alkaline-hypochlorite degraded starch having a decreased viscosity in comparison with the untreated starch.
EP776397 (Chemisolv Limited) describes a process of applying a high molecular weight polymer having a polyhydroxy backbone (e.g., starch) to a substrate, comprising adding to a solution of such material in anionic form a flocculent of oppositely charged form in order to insolubilise such material, and thereafter applying such insolubilised material to said substrate. The subject matter is disclosed as having particular application in respect of production of paper by adding to the slurry supplied in paper production an anionic starch and a cationic flocculent. Preferred flocculants disclosed are polyacrylamide cationic polymer, a copolymerised acrylamide/diallyldimethyl ammonium chloride or mannich acrylamide, or any other high molecular weight cationic (co) polymer carrying a permanently quaternized nitrogen.
JP54059416 describes the joint use of cationic polyamide-epichlorohydrin resin and anionic dialdehyde starch as dry and wet strength enhancer.
U.S. Pat. No. 4,925,530 (The Wiggins Teape Group Limited) discloses a process in which aqueous suspensions of papermaking fibers and filler are each separately treated with an anionic or a cationic polymer, after which the filler or the papermaking fiber is treated with a polymer of opposite charge to that used in the initial treatment. The initial treating polymer is characterized as preferably a papermaking retention aid or flocculent, e.g., a cationic polyacrylamide or an amine/amide/epichlorohydrin copolymer, in the case of cationic materials, or an anionic polyacrylamide, in the case of anionic materials. The further treating polymer is characterized as preferably an anionic or cationic starch, depending on the charge of the initial polymer.
WO9831740 (BASF AG) discloses starches with improved retention on cellulose fibers, useful as dry paper strength agents and as draining and retention acids, which are prepared by treating dry, flowable starch with an aqueous solution of cationic polymers and drying.
DE19701523 (BASF AG) describes a starch, which has been modified with at least one cationic polymer and a method for producing the same. The method for producing the modified starch includes the reaction of an ani
Anderson Kevin Ray
Esser Anton
Fosdick Lawrence Edward
Hwang Ki-Oh
Mahr Norbert
Griffin Steven P.
Hug Eric
Merchant & Gould P.C.
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