Developers toners

Different papers, even different paper grades of the same paper, react differently to toners. Paper developers also affect a toner s color. Test each paper/developer/toner combination before committing valuable work to the process. Keep a book of the results. 

However, it was also reported that the direct condensation of4-(l,l-dimethylethyl)phenol with methanal yields more than the eyelie produets deseribed inequation 11. Linear products are also formed as byproducts [60]. The cyclic products possess other properties in comparison to the linear one and to commercial novolacs, respectively [61], For example, the cyclic calixarenes can form chelates with metal ions. Furthermore, calixarenes are used in eleetrophotographic development toners as negative charge regulators [62]. 

Otaki, K. Suguro, Y. Electrostatographic developer toners containing polymer particles coated with charge-controlling agent. Jpn. Kokai Tokkyo Koho JP 04039673, 1992 Chem. Abstr. 1992,117, 80023. 

Soluble Fluorescent Polymers. Several pigment manufacturers have developed fluorescent polymers iatended to be used as a solution for apphcation to various substrates. These toners come ia both solvent soluble and alkaline water-soluble forms. 

Phenylenediamines are used in a variety of other appHcations, such as corrosion inhibitors, cross-linking agents for epoxy resins, toners for electrostatic image development (35), and to improve wrinkle resistance of cellulose acetate fibers (36). 

The electrophotographic system (102,103) involves two key physicochemical elements a photoreceptor and a toner. The minimum requirements of the process are (/) to charge a photoconductive photoreceptor uniformly (2) to illuminate selectively the photoreceptor to form a latent electrostatic image and (J) to develop the image by applying charged toner. These steps are illustrated in Figure 17. 

Liquid toners are suspensions of toner particles in a fluid carrier. The carrier is typically a hydrocarbon. Dielectric, chemical, and mechanical properties of the Hquid must be compatible with the photoreceptor, the suspended toner particles, and the materials of the development equipment. Liquid toners are capable of producing higher resolution than dry toners because of the smaller (3—5 -lm) particle size achievable. Development of the latent image occurs as it passes through a bath of toner and the charged particles are attracted to the oppositely charged surface. 

Fig. 9. (a) Schematic of charged area development (CAD), using toner charged oppositely to that of the photoreceptor and resulting in a positive document (b) discharged area development (DAD), where the toner and photoreceptor polarity are the same, resulting in a negative document. 

Triboelectricity. For development to occur, the toner particles must be reproducibly charged to the correct level and polarity for the specific photoreceptor. The phenomena of triboelectricity, which involves the transfer of charge from one soHd to another, are exceedingly complex, involving the surfaces of soHds and interaction of the surfaces with each other and with the ambient (52). Consequentiy, the specific experimental observations are highly sensitive to the nature and purity of the materials, the physical and chemical state of both surfaces, and the precise details of the experiments performed. 

Fig. 13. Two-component development involving competition between electrostatic and adhesive forces, where + outside and beneath the large circles represents the positively charged toner and the large circles containing negative signs represent carrier beads.

Development therefore depends on whether the development force exceeds the forces F + Fg which keep the toner attached to the carrier. 

Fig. 14. Two-component magnetic bmsh development showing (a) the magnetic carrier particles (large circles) carrying toner (—), which within the magnetic field of the rotating permanent magnets, behave as individual bar magnets and (b) the production of a developed image. See text.

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