Cellulose derivatives having gel-like rheological properties...

Organic compounds -- part of the class 532-570 series – Organic compounds – Carbohydrates or derivatives

Reexamination Certificate

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C536S084000, C536S090000, C536S091000, C536S095000, C536S096000

Reexamination Certificate

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06958393

ABSTRACT:
A description is given of cellulose derivatives having gel-like rheological properties in aqueous solution characterized in that:a) cellulose is alkalized with aqueous alkali metal hydroxide solution in the presence of a suspension medium,b) the alkalized cellulose is reacted with one or more alkylene oxides,c) then reacted with an alkyl halide present in the suspension mediumd) subsequently or simultaneously the alkalized cellulose is reacted with a crosslinking agent in an amount of 0.0001 to 0.05 eq, where the unit “eq” represents the molar ratio of crosslinking agent relative to the anhydroglucose unit (AGU) of the cellulose used, ande) after, if appropriate, further addition of alkali metal hydroxide and/or alkylating agent, the resultant irreversibly crosslinked cellulose derivative is separated off from the reaction mixture, if appropriate purified and dried.

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patent: 2002/0038018 (2002-03-01), Dannhorn et al.
Dannhorn et al. (EP 1180526 A1) (Process for the preparation of alkyl hydroxyalkyl cellulose) (Abstract Sent).
C.L. Sieglaf: “Proposed Nomenclature for Steady Shear Flow and Linear Viscoelastic Behavior”, Transactions of the Society of Rheology 20:2 month unavailable (1976) 311-317.
N. Sarkar: “Kinetics of thermal gelation of methylcellulose and hydroxypropylmethylcellulose in aqueous solutions”, Carbohydrate Polymers 25 month unavailable (1995) 195-203.
F. Chambon, H.H., Winter: “Linear Viscoelasticity at the Gel Point of a Crosslinking PDMS with Imbalanced Stoichometry”, Journal of Rheology 31 (8) month unavailable (1987) 683-697.
G. Barteimus and R. Ketterer, Z. Anal. Chem. 286 (month unavailable) (1977) 161-190 “Analytik von Celluloseaethergruppen”.

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