Method of producing cellulose dope
AssigneeWeyerhaueser Company
InventorE. Peter Lancaster
Life of this patent
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Abstract
A cellulose dope prepared by subjecting a slurry of cellulose to cavitation either before, during or after treatment with a solvent. The cavitation results in the efficient fibrillization or delamination of the pulp fibers by peeling back the layers of fiber. The cavitation makes the fibers highly accessible to solvents for dissolution. One preferred cellulose solvent is sodium hydroxide at soda cellulose Q condition.
Claims19
A method for the preparation of a cellulose dope for use in regeneration of cellulose comprising:
- subjecting a cellulose slurry that includes underivatized cellulose I to cavitation to expose the cellulose, including the underivatized cellulose I, to dissolution;
- and,
- combining the cellulose slurry with a cellulose solvent.
A method for the preparation of a cellulose dope for use in regeneration of cellulose comprising:
- cavitating a cellulose slurry that includes underivatized cellulose I and having at least 1.5 percent by weight cellulose a plurality of times to expose cellulose in the slurry to dissolution, including the underivatized cellulose I, and to yield a treatment rate of at least about 8 minutes per gram, with a cooling means to maintain a vapor pressure for effective cavitation;
- bringing the cellulose slurry to soda cellulose Q condition, either prior to or subsequent to cavitation, by maintaining the slurry at a temperature of -7.degree. C. to 4.degree. C., and adding NaOH to a concentration of 6 percent to 10 percent by weight.
A method for preparing a cellulose dope, comprising:
- forming an aqueous cellulosic slurry that includes underivatized cellulose I, the cellulose I having a degree of polymerization of at least 400;
- pressurizing the slurry to a pressure of greater than about 1 atmosphere to about 5 atmospheres;
- cavitating the cellulose slurry using an electronic sonicator operating at a frequency of from about 500 Hz to about 1 MHz to expose the cellulose, including the underivatized cellulose I, to dissolution;
- adding to the cellulose slurry a cellulose solvent selected from the group consisting of sodium hydroxide, potassium hydroxide, lithium hydroxide, beryllium hydroxide, cesium hydroxide, and combinations thereof, the solvent having a concentration of from about 6 percent to abut 10 percent by weight of the slurry;
- and
- cooling the slurry to a temperature of from about -7.degree. C. to about 4.degree. C.
Dependencies are inferred from the claim text.