| 摘要 |
<p>An aqueous coating composition comprises (a) a hydrophilic binder; (b) an ester of cellulose having at least 8 acyl groups per C24 cellulose unit wherein at least a majority of the acyl groups are derived from an aliphatic polycarboxylic acid having from 3 to 6 carbon atoms; or a salt of the ester; and optionally (c) a hardening agent in an amount sufficient to render the composition water-insoluble after coating and drying of the composition. The cellulose used in preparing the ester is preferably a deacetylated cellulose acetate prepared by reacting cellulose acetate with an alkali metal alkoxide dissolved in the corresponding alcohol, e.g. sodium methoxide in methanol. The coating composition is useful for forming water-insoluble, conductive and highly-adherent layers in composite bases or elements, and particularly in photographic elements having hydrophobic supports. The conductive layers can be used, for example, as conductive subbing layers or conductive pelloid layers. Salts of cellulose esters that are derived from cellulose prepared as described above, have a lower solution viscosity, and therefore have improved coatability. They are also more conductive than similar salts prepared from cellulose made by deacetylating cellulose acetate with aqueous ammonia.</p> |
