| 摘要 |
<p>The invention is generally accomplished by utilization of a surfactant for very small particle photographic dispersions. Three types of such surfactants that have been identified are as follows: Type A: surfactant comprising 6 to 22 carbon atom hydrophobic tail with one or more attached hydrophilic chains comprising at least 8 oxyethylene and/or glycedyl ether groups that may or may not be terminated with a negative charge such as a sulfate group. Type B: block oligomeric surfactants comprising hydrophobic polyoxypropylene blocks (A) and hydrophilic polyoxyethylene blocks (B) joined in the manner of A-B-A, B-A-B, A-B, (A-B)n=G=(B-A), or (B-A)n=G=(A-B)n, where G is a connective organic moiety and n is between 1 and 3. Type C: sugar surfactants, comprising between one to three 6 to 22 carbon atom hydrophobic tail with one or more attached hydrophilic mono or oligosaccharidic chains that may or may not be terminated by a negatively charged group such as a sulfate group. The preferred colloid chemical criterion of the photographic dispersion material in this invention is that they are formed with particle diameters between about 5 nm and 100 nm that have been prepared by precipitation from solution by a solvent and/or pH shift.</p> |
