| 摘要 |
An alkali-soluble hydroxyethyl cellulose pellet is made from fibrous hydroxyethyl cellulose crumb having from 2 to 8% of ethylene oxide substitution, the pellet having a bulk density which varies from the high range of 30 to 35 lbs. per cu. ft. when the moisture content of the crumb is 40%, to the low range of 20 to 25 lbs. per cu. ft. when the moisture content of the crumb is 58%, the pellets being free of surplus glazing and readily dispersible in water. The hydroxyethyl cellulose, suitably derived from cotton linters or wood pulp (see U.S.A. Specification 2,847,411), is preferably shredded or fluffed before extrusion in a pellet mill. Preferably, 0,05 to 0,20% by weight of a surfactant is added to the hydroxyethyl cellulose crumb before shredding or fluffing. Such a surfactant, e.g. polyethylene glycols and polyethylene-polypropylene glycols, acts p both as a fibre lubricant and dispersant, allowing easy fluffing and improved re-dispersion of the formed pellets. Addition of such a surfactant allows the bulk density of the pellet at each moisture level to be raised by 10 to 20%, without loss of dispersibility. In an example, a hydroxyethyl cellulose feed stock (4% ethylene oxide substitution), of moisture content 45% and containing 0,1% of surfactant, is shredded and extruded into pellets. The pellets are dried to 7% moisture content, and have a bulk density of 30 lbs. per cu. ft. |
