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Diffusion Couplers

Although the varied uses for which DIR couplers are employed call for precise control over where the inhibitor diffuses, the very complexation mechanism by which inhibitors work would seem to preclude such control. The desired ability to target the inhibitor can be attained by the use of delayed release DIR couplers, which release not the inhibitor itself, but a diffusable inhibitor precursor or "switch" (Fig. 16) (98). Substituents (X, R) and stmctural design of the precursor permit control over both diffusivity and the rate of inhibitor release. Increasing the effective diffusivity of the inhibitor, however, means that more of it can diffuse into the developer solution where it can affect film in an undesirable, nonimagewise fashion. This can be minimized by the use of self-destmcting inhibitors that are slowly destroyed by developer components and do not build up or "season" the process (99). [Pg.479]

Fig. 16. Reaction of a delayed release DIR coupler and oxidized developer (Dev ). A delayed released DIR coupler permits fine-tuning of where and when the development inhibitor (In) is generated by releasing a diffusible inhibitor precursor or "switch" as a function of image formation. This permits control... Fig. 16. Reaction of a delayed release DIR coupler and oxidized developer (Dev ). A delayed released DIR coupler permits fine-tuning of where and when the development inhibitor (In) is generated by releasing a diffusible inhibitor precursor or "switch" as a function of image formation. This permits control...
Such dyes often are called azomethines. The nature of the exact color couplers used in color film is not well publicized. It is important that the couplers not diffuse out of the layers where they belong and, for this reason, insolubilizing substituent groups are attached to strategic positions on the color couplers. [Pg.1414]

In another interesting amplification system, an image in silver or other noble metal nuclei is used for catalysis, and a cobalt(III) complex is used as an oxidant in place of a peroxy compound. The amplification permits less silver to be used. An imagewise distribution of silver nuclei is associated with a non-diffusible dye-forming coupler, and the image is amplified by (1) imbibing the system with a solution containing a color developer such as a p-phenylenediamine and (2)... [Pg.117]

Another approach to prevention of diffusion of color couplers has been the incorporation of 2-pyrazolin-5-ones into some type of polymer. [Pg.168]


See other pages where Diffusion Couplers is mentioned: [Pg.140]    [Pg.89]    [Pg.140]    [Pg.89]    [Pg.474]    [Pg.479]    [Pg.480]    [Pg.480]    [Pg.481]    [Pg.487]    [Pg.506]    [Pg.208]    [Pg.109]    [Pg.3459]    [Pg.45]    [Pg.117]    [Pg.168]    [Pg.300]    [Pg.69]    [Pg.101]    [Pg.319]    [Pg.322]    [Pg.91]    [Pg.92]    [Pg.93]    [Pg.93]    [Pg.289]    [Pg.289]    [Pg.260]    [Pg.315]    [Pg.44]    [Pg.524]    [Pg.327]   


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