Toner particle size

Measuring Toner Particle Size Distributions Using Spatial Frequency Analysis... 

Experimental data relating the spatial frequency dependence of image quality parameters obtained from electrophotographic toner deposits with the toner particle size distributions are presented. 

As this work developed it became a working premise that the toner particle size distribution was a major factor determining the image quality characteristics (1,2). The particle size distribution in the following analysis is presumed to be of lognormal form,... 

Figure I. Representative toner particle size distributions used in this study. Key ---------------------------, fraction 5 and------, parent.

The correlation analyses of toner particle size and size distribution parameters and image quality characteristics of toner deposits as measured by the spectral dependence of contrast transfer function and noise show high coefficients of correlation Specifically the Wiener spectrum data appear to yield the weight geometric mean and standard deviation of the toner population in this study. Therefore the Wiener spectrum may be another analytical tool in characterizing particle populations. It must be pointed out that the analysis reported here is mainly empirical. Further work is needed to refine the models and to examine the limits of applicability of these tests. Factors such as particle clumping, non-uniform depositions and optical limitations are specific areas for examination. 

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. 

Let us first assume that we have a spherical particle with a radius of 5 p.m similar to an idealized toner particle, which is comprised of polystyrene, in contact with an electrically conducting substrate. A typical electric charge on a toner particle of that size is of the order of 10" " C. The Hamaker coefficient (Eq. 15) for such as system would be about 1.5 eV. 

Chem. Geol. 157 275-284 Meisel.W. (1989) Corrosion processes and their inhibition as studied by Mdssbauer conversion and other electron spectroscopies. Hy-perfine Interactions 45 73-90 Meisen, U. Kathrein, H. (2000) The influence of particle size, shape and particle size distribution on properties of magnetites for the production of toners. J. Imag. Sci. Techn. 44 508-513... 

Laser printers and many copiers work by the one-component process, which allows the design of particularly compact machines. The principle of the magnetic brush is retained, however, the toner itself is magnetizable. This can be done by dispersing ca. 30-50 wt.% of black, magnetizable iron oxide particles in thermoplastic resins. Apart from the iron oxide, various additives are generally also incorporated to control the electrostatic chargeability, the flow characteristics and the color. The particle size of these toners is ca. 5-15 pm. 

A particle size between 0.2 and 0.5 pm is preferred. High quality toners contain oxides with a narrow particle size distribution as demonstrated in Figures 5.6 and... 

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