| 摘要 |
An aqueous coating fluid is described comprising gelatin at a concentration of at least 1 wt % and gelatin hardener at a level from 1-200 effective mumole hardener per gram of coating fluid, wherein at least 20% of the gelatin comprises a gelatin prepared from hydrolysis of ossein using sodium or potassium hydroxide. Relative improvements are obtained in reducing the rate of chemical gelation of a coating fluid containing gelatin and a hardener, without the need for chemically modifying functional groups of the gelatin. The invention further enables an increase in coating fluid concentration, increase in the fluid viscosity, reduction in the ratio of added anionic polymer to gelatin, and/or increase in the pH of a coating fluid containing gelatin and a hardener, without detrimentally increasing the rate of chemical gelation of the coating fluid. The invention also enables the inclusion of relatively more reactive hardeners in a coating fluid containing gelatin, and/or the inclusion of relatively higher molecular weight gelatin in a coating fluid containing hardener, without detrimentally increasing the rate of chemical gelation of the coating fluid. Each such advantage may be achieved either individually, or in combinations to varying extents.
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