Abstract
The sulfate ester of ethylcellulose is prepared by reacting sodium acetyl sulfate with a partially ethylated cellulose. After a reaction time of less than 1 hr at room tempera ture, the product is isolated as the sodium salt and washed in isopropanol. The dried material is dense, granular, and free-flowing and has good dry-heat and water-solution stability. The water-soluble sodium ethylcellulose sulfate is also soluble in a variety of organic solvents and solvent mixtures. Solubility characteristics can be altered by proper selection of the starting cellulose ether and the degree of sulfation.
This sulfate ester has many possible end uses, because of the unique dual solubility that allows, for coating from volatile solvents. Solvent-cast sheeting is heat-sealable, clear, and water-soluble; it is flexible at low temperature and humidity, when plasti cized with an aliphatic dibasic acid ester. The product is an excellent resin binder for pigments and other solids in both water and water-alcohol. Low-viscosity solutions in organic solvents can be coated and rapidly cured on medicament tablets.
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