| 摘要 |
1,128,513. Capsules. KEUFFEL & ESSER CO. 4 March, 1966 [5 March, 1965], No. 9699/66. Heading B8C. Radiation-sensitive material is included in either the core or the shell of a capsule so that the shell may be disintegrated by means of electromagnetic radiation when the core material is required for use, e.g. for photographic processes such as sensitizing, developing, fixing or stabilizing photographic materials. On absorption of suitable radiation the radiationsensitive material may generate either a gas which produces -sufficient pressure to burst the shell, or heat which melts the shell. If the radiation-sensitive material is included within the core, the walls of the shell must be transparent to the disintegrating radiation. Examples of materials which generate gas on absorption of electromagnetic radiation are aromatic diazonium compounds, aromatic azido compounds and quinone-diazides, all of which produce nitrogen, and ferric salts of an organic dicarboxylic acid such as ferric oxalate and ferric ammonium oxalate, which produce carbon dioxide. Infra-red absorbers which generate heat capable of destroying the capsule shell include carbon black and synthetic absorbers such as manganese complexes of azo compounds. Examples are given in which capsules are formed by deposition of the shell material around dispersed entities of the core material, from a coacervate solution of the former. Coacervation may be induced by the addition of suitable agents, such as petroleum ether. |
