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Visual Coupler for Neutral Diazotype Formulations

IP.com Disclosure Number: IPCOM000075992D
Original Publication Date: 1971-Dec-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Dowden, BF: AUTHOR [+2]

Abstract

Excessive fading of the image due to exposure to high-light intensity is a serious problem with diazotype microfilms. Loss of visual density is accompanied by a drastic color shift from neutral/black to sepia. The so-called black diazotype microfilms usually contain at least two couplers. Examination of the spectra of such films, has shown that it is the dye resulting from the blue coupler which contributes to most of the lack of stability of the film. It was, therefore, decided to screen a number of blue couplers to see if some relationship between light-fade resistance and structure could be determined.

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Visual Coupler for Neutral Diazotype Formulations

Excessive fading of the image due to exposure to high-light intensity is a serious problem with diazotype microfilms.

Loss of visual density is accompanied by a drastic color shift from neutral/black to sepia. The so-called black diazotype microfilms usually contain at least two couplers. Examination of the spectra of such films, has shown that it is the dye resulting from the blue coupler which contributes to most of the lack of stability of the film. It was, therefore, decided to screen a number of blue couplers to see if some relationship between light-fade resistance and structure could be determined.

This study led to the discovery of a coupler, namely, 2,3- dihydroxynaphthalene-6-sulfonic acid which, when coupled with a diazonium salt, gives a dye which is extremely resistant to light fade.

/*/In Table I below there is shown the results of comparative testings of 2,3- dihydroxynaphthalene-6-sulfonic acid and two standard couplers used in commercial films, namely, 2,3-dihydroxynaphthalene and 2-hydroxy-3-naphthoyl- o-aniside. Films were coated by imbibition into triacetate from solutions containing the coupler to be tested, either HD-30 (p-morpholino-2, 5- diethoxybenzenediazonium fluoborate)or DE(BF(4)) (p-diethylamino- benzenediazonium fluoborate) and acid stabilizers. In each coating solution, the amount of diazonium salt was the same and the coupler was added on a molar basis. Normalization is not possibl...