Methods of preparing polysaccharide sheets for esterification
View Patent ↗Processing of cellulose, and more particularly, fiber opening and downstream processing and chemistry are provided. A process includes moistening a cellulose sheet stock to a water content in a range from about 20% to about 50%, attriting the moistened cellulose sheet to a wet pulp, flash drying the wet pulp to a floccule of cellulose having a moisture content from about 4% to about 8%, and esterifying the floccule of cellulose to provide a cellulose ester product.
1. A process comprising:
moistening a cellulose sheet stock to a water content in a range from about 20% to about 50%;
attriting the moistened cellulose sheet to a wet pulp;
flash drying said wet pulp to a floccule of cellulose having a moisture content from about 4% to about 8%, wherein flash drying is conducted in a flash dryer having an inlet temperature of about 105° C. to about 200° C. and an outlet temperature of about 60° C. to about 130° C.; and
esterifying said floccule of cellulose to provide a cellulose ester product.
2. The process of claim 1 , wherein moistening said cellulose sheet comprises treatment with demineralized water.
3. The process of claim 1 , wherein attriting comprises the steps of:
shredding said cellulose sheet stock into small fragments; and
attriting said small fragments into said wet pulp.
4. The process of claim 1 , wherein flash drying is conducted with a low pressure hot gas, wherein said low pressure is in a range from between about 2 to about 4 psig.
5. The process of claim 1 , wherein the flash drying step is conducted with air that is heated indirectly.
6. The process of claim 1 , further comprising separating said floccule of cellulose in a cyclone separator.
7. The process of claim 1 , wherein the esterification step comprises treatment with acetic anhydride, propionic anhydride, butyric anhydride, a mixed anhydride, and combinations thereof.
8. The process of claim 1 , wherein said process is used to produce a cellulose acetate having a degree of substitution from about 0.1 to about 3 acetate groups per monomer unit.
9. The process of claim 1 , wherein said process is used to produce cellulose diacetate, cellulose triacetate, fiber grade cellulose acetate, water-soluble cellulose acetate, or combinations thereof.
10. The process of claim 1 , further comprising forming a fiber tow from said cellulose ester product.
11. The process of claim 1 , further comprising incorporating said cellulose ester product in a composite matrix comprising one selected from the group consisting of a thermoplastic and a thermoset.
12. The process of claim 10 , further comprising incorporating said cellulose ester tow in a composite matrix comprising one selected from the group consisting of a thermoplastic and a thermoset.
13. A process comprising:
(a) moistening a cellulose sheet stock to a water content in a range from about 20% to about 50%;
(b) attriting the moistened cellulose sheet to a wet pulp;
(c) flash drying said wet pulp to a floccule of cellulose having a moisture content from about 5% to about 8%, wherein flash drying is conducted in a flash dryer having an inlet temperature of about 105° C. to about 200° C. and an outlet temperature of about 60° C. to about 130° C.;
(d) esterifying said floccule of cellulose to provide a cellulose ester product; and
(e) forming a fiber tow from said cellulose ester product.
14. The process of claim 13 , wherein moistening said cellulose sheet comprises treatment with demineralized water.
15. The process of claim 13 , wherein attriting comprises the steps of:
shredding said cellulose sheet stock into small fragments; and
attriting said small fragments into said wet pulp.
16. The process of claim 13 , wherein flash drying is conducted with a low pressure hot gas, wherein said low pressure is in a range from between about 2 to about 4 psig.
17. The process of claim 13 , wherein the flash drying step is conducted with air that is heated indirectly.
18. The process of claim 13 , further comprising separating said floccule of cellulose in a cyclone separator.
19. The process of claim 13 , wherein the esterification step comprises treatment with acetic anhydride, propionic anhydride, butyric anhydride, a mixed anhydride, and combinations thereof.
20. The process of claim 13 , wherein said process is used to produce a cellulose acetate having a degree of substitution from about 0.1 to about 3 acetate groups per monomer unit.
21. The process of claim 13 , wherein said process is used to produce cellulose diacetate, cellulose triacetate, fiber grade cellulose acetate, produce water-soluble cellulose acetate and combinations thereof.
22. The process of claim 13 , further comprising incorporating said cellulose ester tow thereof in a composite matrix comprising one selected from the group consisting of a thermoplastic and a thermoset.
23. A process comprising:
moistening a cellulose sheet stock to a water content of the cellulose sheet stock is about 20% to about 50%;
attriting the moistened cellulose sheet to a wet pulp, wherein a water content of the wet pulp is about 20% to about 50%;
delivering the wet pulp to a flash dryer;
flash drying said wet pulp to a floccule of cellulose, wherein a water content of the flocculate of cellulose is about 4% to about 8%, and wherein the flash dryer has an inlet temperature of about 105° C. to about 200° C. and an outlet temperature of about 60° C. to about 130° C.; and
esterifying said floccule of cellulose to provide a cellulose ester product.