Overcoat Photoreceptor Technology

In the printing market, there has been growing demand for xerographic digital printing with excellent print-on-demand capability. At the same time, customers also require stable image quality equivalent to that of offset printing. In xerography, a photoreceptor is essential in the printing process, and uneven wear and degradation of its surface adversely affect stable image quality. Therefore, Fuji Xerox has designed strong and chemically stable materials for the overcoat layer (OCL) at the molecular level. This OCL technology is incorporated in photoreceptors available for the production market, thereby achieving fine wear resistance, stable electrical characteristics, and sustainable chemical stability for long-term use.

The following describes our OCL technology used for the overcoat photoreceptor.

  1. Controls the crosslink density of materials in the OCL by mixing tetrafunctional (having four reactive sites) and bifunctional reactive charge transport materials in the OCL to improve its wear resistance.
  2. Ensures the transportability of electron holes (positively charged) by increasing the ratio of said reactive charge transport materials included in the OCL as much as possible.
  3. Prevents oxidation of the materials included in the OCL by optimizing the amount of reactive charge transport materials with different ionization potential, in order to strengthen chemical stability in the OCL.

As a result, we have successfully reduced the depth of wear to about one-fifth of that in our conventional products and minimized uneven wear to provide stable image quality approaching that of offset printing.

Fig. 1: Sectional View of the Overcoat Layer