Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1999-07-14
2000-12-12
Boykin, Terressa
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525 5424, C08F11606
Patent
active
061600504
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to starches in undigested or digested form which are modified with polymers which contain cationic groups and/or groups which can be converted into cationic groups, a process for their preparation and their use as assistants in the production of paper, board and cardboard, in particular as dry strength agents for paper.
Ullmanns Encyklopadie der Technischen Chemie, 4th Edition, Verlag Chemie, Weinheim, 1979, Vol. 17, 581 et seq., describes generally the use of digested, water-soluble starches and of water-soluble starch derivatives as assistants for papermaking, in particular for increasing the strength of the paper. However, the retention of the dissolved starches in the paper is low, leading to considerable pollution of the waste waters.
U.S. Pat. No. 3,734,820 describes the use of cationic dextran graft copolymers as additives for improving the dry strength of paper. The graft copolymers are added to an aqueous cellulose dispersion. This mixture is then used for the production of paper sheets. The graft copolymers are prepared by grafting dextran, a naturally occurring polymer having an average molecular weight of from about 20,000 to about 50,000,000, with cationic monomers, for example diallylic, quaternary ammonium compounds, such as diallyldimethylammonium chloride, or acrylic, quaternary ammonium compounds, such as dimethylaminoethyl methacrylate and mixtures thereof with acrylamide or methacrylamide. The graft copolymerization is preferably carried out in the presence of a redox catalyst, for example one based on cerium.
U.S. Pat. No. 3,467,608 describes a process for the preparation of a cationic starch by heating an aqueous starch suspension with the addition of a polyalkyleneimine, eg. polyethyleneimine, or of a polyalkylenepolyamine, such as polyethylenepolyamine, the molecular weight of the polymer used for the modification being at least 50,000. The reaction mixture contains from 0.5 to 40% by weight of the polymer and from 60 to 99.5% by weight of starch, the percentages being based on the solids content. The resulting cationic starch derivatives are used as flocculents.
U.S. Pat. No. 4,097,427 describes a process for converting starch into cationic form, and aqueous starch suspension being reacted under alkaline reaction conditions with a water-soluble polymer which contains quaternary ammonium groups in the presence of an oxidizing agent. Quaternized polyethyleneimines, quaternized diallyldialkylamine polymers, etc. are suitable. For example, ammonium persulfate, hydrogen peroxide, sodium hypochlorite, ozone or tert-butyl hydroperoxide is used as the oxidizing agent. The pH of the starch suspension is brought to about 8 with water-soluble bases. The modified cationic starches thus prepared are added to the paper stock as dry strength agents in papermaking. In this process, however, the waste water has a very high COD value.
U.S. Pat. No. 4,146,515 describes a process for the preparation of a gelatinous, cationic starch for the surface sizing and coating of cellulosic materials. An aqueous suspension of a partly oxidized starch, together with a cationic polymer, is digested in a continuous digester. The cationic polymers used are condensates of epichlorohydrin and dimethylamine, polymers of diallyldimethylammonium chloride, quaternized reaction products of vinylidene chloride and ammonia, quaternized polyethyleneimine and quaternized polyepichlorohydrin.
DE-A-37 19 480 and EP-A-0 282 761 describe a process for the production of paper, board and cardboard having high dry strength by adding a dry strength agent comprising a mixture of cationic polymers and starch to the paper stock. The cationic polymers contain polymerized units of diallyldimethylammonium chloride, N-vinylamine or N-vinylimidazoline as characteristic monomers. It is also possible to use polyethyleneimine as the cationic polymer. For the preparation of the dry strength agents, either an aqueous suspension or a natural potato starch is digested in the presence of the polymers by heating to above
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Ettl Roland
Lorencak Primoz
Niessner Manfred
Nilz Claudia
Rubenacker Martin
BASF - Aktiengesellschaft
Boykin Terressa
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