GB1338695A - Methods of forming negative and positve azo dye images - Google Patents

Abstract

1338695 Diazctype processes for producing positive or negative images SCOTT GRAPHICS Inc 22 April 1971 [27 April 1970] 10840/71 Heading G2C Negative dye images are produced by (i) imagewise exposing a material comprising an aryl diazosulphonate and a coupler to light of wavelengths equal to or greater than the absorption maximum of the diazosulphonate to convert the diazosulphonate to a labile form unaffected by such wavelengths (ii) uniformly heating to above 150‹C so that the labile form couples with the coupler and (iii) uniformly exposing to light of wavelengths equal to or greater than absorption maximum of the diazosulphate and also to light of wavelengths equal to or less than the absorption maximum of the labile form so that the remaining diazosulphonate is converted to the labile form which is then decomposed. Negative dye images may also be produced by uniform exposure in step (i) followed by imagewise heating in step (iii) and exposure to wavelengths equal to or less than the absorption maximum of the labile form to decompose any remaining labile form. Positive dye images are produced by uniform exposure as in step (i) followed by imagewise exposure to light of wavelengths equal to or less than the absorption maximum of the labile form to decompose the labile form and then heating to above 150‹F to couple the remaining labile form with the coupler. Positive dye images may also be produced by imagewise exposure to wavelengths as in step (iii) so that the labile form produced is decomposed followed by uniform exposure as in step (i) above to convert the remaining diazosulphonate to the labile form and then uniformly heating to above 150‹C to form the dye image. The light-sensitive layer may be coated on a polyester support subbed with cellulose acetatebutyrate. In the examples, the material is imagewise exposed to wavelengths of 360 nm and above (the absorption maximum of the diazosulphonate developed by heating to 200‹ F. to produce negative image and fixed by exposure to light having at least one wavelength of 300 nm (absorption maximum of labile form) and are wavelength above 360 nm. A positive dye image is produced by uniform exposure to wavelengths above 360 nm, imagewise exposure to 300 nm and development by heating to 200‹F.