Sugar – starch – and carbohydrates – Products – Modified starches
Patent
1997-04-29
1998-12-22
Griffin, Walter D.
Sugar, starch, and carbohydrates
Products
Modified starches
127 67, 127 71, 1621646, 1621682, 162175, C08B 3012, C08B 3000, D21H 1100
Patent
active
058513000
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for cationically modifying starch by reacting starch with polymers which contain amino and/or ammonium groups in an aqueous medium at above the glutinization temperature of the starch in the absence of oxidizing agents, polymerization initiators and alkali.
2. Description of the Background Art
For increasing the dry strength of paper, for example, Ullmanns Encyklopadie der technischen Chemie, 4th edition, Verlag Chemie, Weinheim-N.Y. 1979, Volume 17, page 581, discloses the use of aqueous suspensions of natural starches, which are converted into a water-soluble form by heating, as a pulp additive in papermaking. However, the retention of the starches dissolved in water on the paper fibers in the paper stock is low. An improvement in the retention of natural products on cellulose fibers in papermaking is disclosed, for example, in U.S. Pat. No. 3,734,820. Said publication describes graft copolymers which are prepared by grafting dextran, a naturally occurring polymer having a molecular weight of from 20,000 to 50 million, with cationic monomers, e.g. diallyldimethylammonium chloride, mixtures of diallyldimethylammonium chloride and acrylamide or mixtures of acrylamide and basic methacrylates, such as dimethylaminoethyl methacrylate. The graft polymerization is preferably carried out in the presence of a redox catalyst.
U.S. Pat. No. 4,097,427 discloses a process for cationically modifying starch, in which the cooking of the starch is carried out in an alkaline medium in the presence of water-soluble quaternary ammonium polymers and of an oxidizing agent. Suitable quaternary ammonium polymers include quaternized diallyldialkylamino polymers or quaternized polyethyleneimines. Examples of oxidizing agents used are ammonium persulfate, hydrogen peroxide, sodium hypochlorite, ozone and tert-butyl hydroperoxide. The modified cationic starches which can be prepared in this manner are added to the paper stock as dry strength agents in papermaking. However, waste water has a very high COD (chemical oxygen demand).
U.S. Pat. No. 4,146,515 discloses a process for the preparation of cationic starch which is used for surface sizing and coating of paper products and oxidized starch is digested together with a cationic polymer in a continuous digester. Suitable cationic polymers are condensates of epichlorohydrin and dimethylamine, polymers of diallyldimethylammonium chloride, quaternized reaction products of ethylene chloride and ammonia, quaternized polyethyleneimine and quaternized polyepichlorohydrin.
U.S. Pat. No. 3,467,608 discloses a process for the preparation of a cationic starch, in which a suspension of starch in water is heated together with a polyalkyleneimine or polyalkylenepolyamine having a molecular weight of at least 50,000 for from about 0.5 to 5 hours at from about 70.degree. to 110.degree. C. The mixture contains from 0.5 to 40% by weight of polyalkyleneimine or polyalkylenepolyamine and from 99.5 to 60% by weight of starch. According to Example 1, a polyethyleneimine having an average molecular weight of about 200,000 is heated in dilute aqueous solution with potato starch for 2 hours at 90.degree. C. The modified potato starch can be precipitated in a mixture of methanol and diethyl ether. The reaction products of starch and polyethyleneimine or polyalkylenepolyamines are described in U.S. Pat. No. 3,467,608 and are used as flocculants.
EP-A-0 282 761 and DE-A-3 719 480 disclose production processes for paper, dry strength agents used are reaction products which are obtainable by heating natural potato starch with cationic polymers, such as polymers or polyethyleneimines containing vinylamine, N-vinylimidazoline or diallyldimethylammonium units in an aqueous medium to above the glutinization temperature of the starch in the absence of oxidizing agents, polymerization initiators and alkali.
EP-B-0 301 372 discloses a similar process in which appropriately modified, enzymatically degraded starches are use
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Ullmanns Encyklopadie der technischen Chemie vol. 17, p. 581 month not available.
Denzinger Walter
Hartmann Heinrich
Linhart Friedrich
Meixner Hubert
Niessner Manfred
BASF - Aktiengesellschaft
Griffin Walter D.
Hailey Patricia L.
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