Photocopying process

Diazidonaphthalene. Pale yel crysts, mp 95—100° with decompn prepd by the bis-diazotation of 1,8-diajninonaphthalene followed by treatment with Na azide (Ref 5). It has been patented as a photosens ingredient in a photocopying process (Ref 6) 2,3-Diazidonaphthalene. Needles from petr eth (bp 40—60°), mp 63—4° prepd in five steps starting with 3-amino-2-naphthoic acid. Its pyrolysis in a Pyrex tube at 400° gave... 

Taking advantage of the sensitivity to light shown by the diazoazoles allows them to be used in the photomechanical reproduction process to produce light sensitive layers or in photocopying processes as precursor of the azo dyes to be generated in situ. 

In the dye line photocopying process, paper or other base material is coated with a solution of a stable diazo compound and a coupling component and then dried. The diazoazoles used are 2-diazopyrrole, 3-diazopyrrole,4-diazopyrazole, 3-diazoindazole, and 4-diazoimidazole deriv-... 

Develop. The latent image is rendered visible by the attachment of oppositely charged toner particles to the drum or belt positive in the photocopying process and negative in laser printing... 

Organic solids have received much attention in the last 10 to 15 years especially because of possible technological applications. Typically important aspects of these solids are superconductivity (of quasi one-dimensional materials), photoconducting properties in relation to commercial photocopying processes and photochemical transformations in the solid state. In organic solids formed by nonpolar molecules, cohesion in the solid state is mainly due to van der Waals forces. Because of the relatively weak nature of the cohesive forces, organic crystals as a class are soft and low melting. Nonpolar aliphatic hydrocarbons tend to crystallize in approximately close-packed structures because of the nondirectional character of van der Waals forces. Methane above 22 K, for example, crystallizes in a cubic close-packed structure where the molecules exhibit considerable rotation. The intermolecular C—C distance is 4.1 A, similar to the van der Waals bonds present in krypton (3.82 A) and xenon (4.0 A). Such close-packed structures are not found in molecular crystals of polar molecules. 

A more recently introduced concept, described by Staniforth et al. (17), involves the use of electrophotographic principles (essentially those used in the photocopying process) as a basis for the application of dry powder coatings to pharmaceutical tablets. This concept is illustrated in Figure 19. 

The metal (M usually Al) is in fact the centre of the drum. This is coated with a thin layer of semiconductor (Sc) which is an insulator in the dark but becomes conductive when exposed to light. The whole photocopying process takes place in several stages. 

The first step in the photocopy process is for the dmm to acquire a uniform static electric charge. The method used is slightly fancier than the... 

Photoconduction forms the basis of electroreprography. In this photocopying process, or xerography as it is sometimes known, a photoconductive material is coated onto a metal drum and uniformly charged (sensitized) in darkness by a corona discharge. The drum is then exposed to the bright image of... 

About half of all zinc oxide produced is used by the rubber industry. About 10% of the zinc oxide is used by the coatings industry. Another 10% is used in the photocopying process. ZnO is also used in ceramics and as a general chemical feedstock. 

A structure containing four-membered chelate rings [7] was first proposed for these polymers 15), but was soon discarded by subsequent workers 11, 22) who favored the five-ring structure [8]. The most recent work on the structure of copper rubeanate indicates that it possesses a three-dimensional structure 16, 30). A solid-solid reaction between dithiooxamide and copper(II) bis(8-hydroxyquinolinate) yielded a product that was fractionated into several different crystalline fractions. A detailed study of the infrared, magnetic and electrical properties of these products supported structures [11] and [12], They differ in that [11] has copper atoms in both directions, whereas, the copper atoms of [12] are all in one plane. The reaction of copper with rubeanic acid has been patented as the basis of a photocopying process 13). 

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