Method of preparing a cellulose carbamate solution
AssigneeZimmer, Inc.
InventorsHarry Schleicher, Bodo Borrmeister, Hermann Lang
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Abstract
The present invention concerns a method of preparing a cellulose carbamate solution by dissolving cellulose carbamate in sodium hydroxide solution at temperatures of <10° C., wherein an 8% to 15% cellulose carbamate solution with a sodium hydroxide concentration of 7% to 12% is prepared in a first step, and then the solution is adjusted to a sodium hydroxide concentration of <9% by diluting with dilute sodium hydroxide solution and/or water in a second step, with the provision that the weight ratio of cellulose carbamate to sodium hydroxide in both steps is >1.
Claims7
A process for preparing a cellulose carbamate solution, the process comprising
- a) preparing an 8% to 15% cellulose carbamate solution with a sodium hydroxide concentration of 7% to 12% by dissolving cellulose carbamate in a sodium hydroxide solution at a temperature of less than 10° C., and
- b) adjusting the sodium hydroxide concentration of the cellulose carbamate solution to a concentration that is less than the concentration in a) and less than 9% by adding to the cellulose carbamate solution either
- i) a single diluent comprising a dilute sodium hydroxide solution or water, or
- ii) a first diluent followed by a second diluent, wherein one of said diluents is water and the other is a dilute sodium hydroxide solution,
- provided that the weight ratio of cellulose carbamate to sodium hydroxide in both (a) and (b) is greater than 1.
The process according to 1, wherein in (a) the cellulose carbamate solution contains 9% to 12% cellulose carbamate with a sodium hydroxide concentration of 8% to 10%, which in (b) is adjusted to at most 8% sodium hydroxide.
Dependencies are inferred from the claim text.