Antistat layers

Examples of known phosphazene polymer blends are those in which phosphazenes with methylamino, trifluoroethoxy, phenoxy, or oligo-ethyleneoxy side groups form blends with poly(vinyl chloride), polystyrene, poly(methyl methacrylate), or polyethylene oxide).97 100 IPNs have been produced from [NP(OCH2CH2OCH2CH2OCH3)2] (MEEP) and poly(methyl methacrylate).101-103 In addition, a special type of IPN has been reported in which a water-soluble polyphosphazene such as MEEP forms an IPN with a silicate or titanate network generated by hydrolysis of tetraethoxysilane or tetraalkoxytitanane.104 These materials are polyphosphazene/ceramic composites, which have been described as suitable materials for the preparation of antistatic layers in the manufacture of photographic film. 

By adding an antistatic agent (complex non-ionic or cationic materials), the surface resistivity is reduced, along with a reduction in static charge accumulation. The agent functions by the formation of an antistatic layer on the surface, which by attraction of moisture and in combination with the antistatic agent itself, conducts away charges. 

Various copolymers with the basic backbone of —Ar—NH—Ar—S—, i.e., aromatic amino sulfide copolymers have been synthesized. This type of copolymer is semiconducting and can be used in many electronic and electro-optical applications. Examples of such applications are antistatic layers, electromagnetic-shielding layers, anticorrosion layers, batteries, electroluminescent devices, and in electronic circuits, such as conductor tracks of transistors. 

Figure 5.1. Generic multilayer photographic film element shown in cross-section, illustrating the key morphological components overcoats, emulsion layers, subbing layer, support and antistat layer. The layer thicknesses are not drawn proportionately to scale. A typical emulsion layer may be 3-6 pm thick, a typical overcoat or interlayer may be 1-2 pm thick, and the support is typically of the order of 100 pm in thickness...

Finally we address the emulsion layers that contain light-sensitive silver halide. Some of these other layers, as discussed above, contain particulates such as matte beads in overcoats, nanoparticulate semiconductors in antistat layers, copolymeric latexes in subbing layers, etc. Such layers are intrinsically composite multiphase layers, and this is also the case for the light-sensitive emulsion layers. In addition to microcrystals or nanocrystals of silver halide, present to capture light and to form developable... 

In a second commercial antistatic application, PEDTPSS was used as the conductive ingredient in an outer surface antistatic layer on CRTs to avoid dust contamination during manufacture and use (Figure 10.7). In addition to the advantages described above, the PEDT PSS layer was found to enhance optical contrast in the displays. PEDT PSS antistatic layers for optical applications such as this require a low content of large particles, sufficient hardness, high adhesion on glass, and a surface resistance about 10 fl/sq. 

The other uses of PEDT PSS for antistatic layers are numerous [43,44] and include antistatic gloves [49], carrier tapes, displays and video display panels [50-52], textiles [53], antistatic release films [54,55], protective films [56], recording tapes [57], and polarizers [58]. 

PEDOTiPSS was first introduced in an industrial product as a roll-to-roll deposited antistatic layer on biaxially oriented poly(ethylene terephthalate) (PET) during photographic film production in order to avoid unwanted, stray electrostatic discharges within the photoactive layers during film processing. The use of PEDOTiPSS as the conductive ingredient in the antistatic layer proved particularly advantageous because... 

Antistatic layers in computer disks by Hitachi-Maxwell [243]... 

Unsubstituted polypyrrole is also insoluble and infusible and hence cannot be processed into coatings and films. Plastic films coated with an antistatic layer of polypyrrole have been prepared by polymerizing pyrrole on the surface of the film or by use of polypyrrole grafted onto latex particles [50]. Nonetheless, polypyrroles are less attractive than polyanilines because of their high absorption at practically all wavelengths in the visible spectrum. 

Polyisothianaphthenes are interesting because of their low absorption in the visible region. Antistatic layers suitable for photographic materials have been prepared by dispersion of polyisothianaphthene in aqueous A-carrageenan [51]. Nonetheless, they have not been extensively studied owing to difficulty in synthesis of the polymer. 

Therefore the polycondensates workgroup within the Bayer Central Research Department started several projects regarding polyheterocycles in the second half of the 1980s. First, work was focused on polypyrrole, particularly for antistatic layers on thermoplastics like polycarbonate (molded parts or sheets). " After less than two years, the Bayer workgroup was forced to terminate these activities by the intrinsic drawbacks of polypyrrole, like toxicity and high vapor pressure of the monomer, and the intense color and poor transparency of polypyrrole layers itself. 

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