Process for the treatment of cellulose
First Claim
1. A process for treatment and activation of cellulose for subsequent chemical reactions which comprises the steps of:
- a) contacting cellulose pulp of an alpha-cellulose content of at least 92 mass % with liquid ammonia at a pressure higher than atmospheric pressure in a pressure vessel at room temperature or at a temperature higher than room temperature, to obtain said cellulose pulp in the activated state;
b) allowing the ammonia to expand and escape by suddenly reducing the pressure in said pressure vessel to atmospheric pressure, removing the ammonia still remaining in the pressure vessel, except for an amount of residual ammonia necessary to maintain said cellulose pulp in the activated state which is maintained in contact with said cellulose pulp;
c) maintaining said state of activation by replacing said residual ammonia by addition of a swelling or an inclusion agent other than ammonia.
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Accused Products
Abstract
The process for the treatment of cellulose for activation for subsequent chemical reactions by bringing the cellulose in contact with liquid ammonia at a pressure higher than atmospheric pressure in a pressure vessel and subsequent expansion by rapid reduction of the pressure to atmospheric pressure, is carried out by using a cellulose pulp of an alpha-cellulose content of at least 92 mass %, letting the ammonia act on the pulp at room temperature or at a temperature higher than room temperature, after the expansion, removing the ammonia then still remaining in the pressure vessel except for a minimum content at which the state of activation reached by the action of the ammonia is still maintained and finally replacing the residual ammonia still needed to maintain the state of activation by another swelling or inclusion agent. The process is suitable, also on a large industrial scale, especially for the activation of pulp subsequently to be acetylated and makes possible to achieve a homogenous and high-grade activation. Further, no costly cooling apparatus is needed.
63 Citations
12 Claims
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1. A process for treatment and activation of cellulose for subsequent chemical reactions which comprises the steps of:
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a) contacting cellulose pulp of an alpha-cellulose content of at least 92 mass % with liquid ammonia at a pressure higher than atmospheric pressure in a pressure vessel at room temperature or at a temperature higher than room temperature, to obtain said cellulose pulp in the activated state; b) allowing the ammonia to expand and escape by suddenly reducing the pressure in said pressure vessel to atmospheric pressure, removing the ammonia still remaining in the pressure vessel, except for an amount of residual ammonia necessary to maintain said cellulose pulp in the activated state which is maintained in contact with said cellulose pulp; c) maintaining said state of activation by replacing said residual ammonia by addition of a swelling or an inclusion agent other than ammonia. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification