Electrophotographic plates

In other areas, POD has been used to improve the wear resistance of a mbber latex binder by incorporation of 25% of Oksalon fibers. Heat-resistant laminate films, made by coating a polyester film with POD, have been used as electrical insulators and show good resistance to abrasion and are capable of 126% elongation. In some instances, thin sheets of PODs have been used as mold release agents. For this appHcation a resin is placed between the two sheets of POD, which is then pressed in a mold, and the sheets simply peel off from the object and mold after the resin has cured. POD-based membranes exhibit salt rejection properties and hence find potential as reverse osmosis membranes in the purification of seawater. PODs have also been used in the manufacturing of electrophotographic plates as binders between the toner and plate. These improved binders produce sharper images than were possible before. 

The photoconductivity of organic dyes, especially phthalocyanine pigments, could be utilized to provide reusable or non-reusable electrophotographic plates having sensitivities that extend over the entire visible spectrum and produce high-contrast images 167,168) Microcrystalline dispersions of metal-free phthalocyanine in suitable binders have a white-light sensitivity equal to that of selenium 169> and can be incorporated into coated papers and drums. 

Count An electrophotographic plate for producing an electrostatic latent image on the... 

The electrophotographic process may also be effected without any carrier here the developer particles may be charged by spraying [433] or superimposing an electric field [434]. In the first case the electrophotographic plate is placed in a jet of gas containing suspended developer particles [435]. 

The flow behaviour of polymeric electrophotographic toner systems containing carbon black varying in surface area and concentration were determined using a cone and plate rheometer [51]. As the concentration of carbon black was increased, the viscosity at low shear rates become unbounded below a critical shear stress. The magnitude of this yield stress depended primarily on the concentration and surface area of the carbon black flller and was independent of the polymer (polystyrene and polybutyl methacrylate) and temperature. It was postulated that at low shear rates the carbon black formed an independent network within the polymer which prevented flow. 

Electrophotography. The main stages of the electrophotographic process consist of charging the photoconductive layer on the conducting plate, formation of the latent potential image under illumination, and visualization of the image. 

Imada, E. Sugimura, H. Katayama, S. Tsuchimoto, S. Hijikigawa, M. Electrophotographic organic plates with optical filters for red color images. Jpn. Kokai Tokkyo Koho JP 63077063, 1988 Chem. Abstr. 1988,109, 119634. 

Katayama, K. Nishigori, Y. Nakano, S. Electrophotographic hthographic plate for laser beam. Jpn. Kokai Tokkyo Koho JP 09138514,1997 Chem. Abstr. 1997,127. 58019. 

Organic electrophotographic photoreceptors are also widely used in laser printers [13,14]. The principal of these printers is almost the same as in a photocopier except the direct generation of the image by a laser instead of the optical system in a copier. Photoreceptors of the laser printers have to absorb in the near infrared range of spectrum. The third area in which photoconductive polymers or polymer composites are applied are electrophotographic printing plates. 

In the electrophotographic imaging process with cholesteric liquid crystals, a standard selenium plate 50 thick on a metal substrate is coated with the liquid crystal film. The sandwich structure thus obtained is shown in Fig. 6a. This sandwich structure is now charged as illustrated in Fig. 6b. Since the liquid crystal film is not a perfect insulator, the charges migrate through the liquid crystal to selenium interface (Fig. 6c). The sandwich is now exposed as shown in Fig. 6d and positive charges on the selenium surface only remain in unexposed (dark) areas. 

Besides the application of photoconductive polymers in photocopiers these materials are also widely used in laser printers in the last years. The third area in which photoconductors are applied is the manufacturing of electrophotographic printing plates. 

Thermosetting aqueous resins Electrophotographic printing plate resins... 

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