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Verfahren zur Herstellung von Pfropfcopolymeren aus Staerke, tert-Alkylazocyanocarbonsaeureester sowie Pfropfcopolymere und deren Verwendung

Production of starch-based graft copolymers for used as flocculating agents involves reacting amylose derivatives with tertiary alkyl azocyanocarboxylic acid derivatives and polymerizing with vinyl comonomers.
: Bruzzano, S.; Sieverling, N.; Jaeger, W.

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DE 2001-10134560 A: 20010716
DE 2001-10134560 A: 20010716
WO 2002-EP7829 A: 20020715
DE 10134560 A1: 20030206
Patent, Electronic Publication
Fraunhofer IAP ()

Die Erfindung betrifft ein Verfahren zur Herstellung von Pfropfcopolymeren mit einem aus Staerke und/oder deren Derivaten gebildeten Rueckgrat. Die Herstellung erfolgt dabei ueber tert-Alkylazocyanocarbonsaeureester von Staerke die durch radikalische Reaktion mit Vinylmonomeren gekoppelt werden. Ebenso betrifft die Erfindung Pfropfcopolymere von Staerke, deren Dispersionen sowie die Verwendung der Pfropfcopolymere.


WO2003008473 A UPAB: 20030410 NOVELTY - Starch-based graft copolymers are obtained by reacting amylose derivatives with tertiary alkylazocyanocarboxylic acid derivatives in presence of an acid acceptor, adding vinyl monomers and polymerizing by thermal activation with cleavage of nitrogen and formation of starch radicals. DETAILED DESCRIPTION - A method for the production of graft copolymers with a starch-based backbone from amylose of formula (I) and/or amylopectin derived therefrom: R1-R5 = H, SO3Na, PO(ONa)2, NO2, C(S)SNa, 1-20C alkyl or acyl, or aryl (optionally with cationic, anionic, hydrophobic and/or amphiphilic substituents), where R3 can also be selected in such a way as to provide a linkage to other glucose units with formation of amylopectin; n = 300-60000 The method involves; (a) reaction in presence of an acid acceptor with a tertiary alkylazo-cyanocarboxylic acid derivative of formula (II): R6 = 1-20C alkyl or carboxyalkyl; R7-R9 = 1-5C alkyl or phenyl; X = halogen or ROO-; R = alkyl, aryl or aralkyl (b) addition of vinyl monomer(s); and (c) initiation of polymerisation by thermal activation at 25-120 deg. C, with cleavage of N2 and formation of starch radicals. INDEPENDENT CLAIMS are also included for (1) tertiary alkylazocyano-carboxylate esters derived from amylose of formula (III); (2) graft copolymers of starch etc. derived from amylose of formula (III); and (3) dispersions of these graft copolymers. In esters (1), formula (III) is as shown for formula (I) with R1-R5 = as above, but with at least one of the groups having the formula -CO-R6-C(CN)(CH3)-N=N-CR7R8R9 (IV); R6 = 1-20C alkyl or carboxyalkyl (optionally substituted or containing in-chain hetero-atoms) In graft copolymers (3), formula (III) is as formula (I) with R1-R5 = H, etc. as above, or a group of formula -CO-R6-C(CN)(CH3)- (R10)m (V); R10 = a vinyl monomer unit; m = 10-10000 USE - Graft copolymers obtained by this method are used as flocculating agents (claimed). Applications include the removal of suspended solids from aqueous systems. ADVANTAGE - Enables the production of starch-based graft copolymers which are free from homopolymers, using a wide range of vinyl comonomers. Graft copolymers of this type with cationic vinyl monomers show excellent flocculating properties in aqueous suspensions, giving considerably better separation in a shorter time compared with conventional cationic starch.