Molecular Simulation Technology for Toner Material

The xerographic process used in printers and multi-function devices is one of high complexity. It involves a multitude of functional materials, such as toner and photoreceptors, and takes advantage of a wide range of physical phenomena, such as electromagnetic fields, the deformations of structures, and the transmission of heat. At Fuji Xerox, we are currently undertaking research to shed light on the mechanisms behind these complex phenomena by replicating the molecular structures and physical properties of functional materials using numerical simulation.

In the xerographic process, an image is created by applying heat to toner, which then melts. This is done in the fusing process. As image quality and power consumption are heavily influenced by the melting performance in this process, it is vital that the composition and molecular structure of toner materials be engineered to exhibit optimal melting properties. It proved to be considerably difficult, however, to directly observe the structure and measure the motion of molecules at the nano level.

To address this, Fuji Xerox developed technology that made it possible to conduct molecular simulations of toner materials. Through its use of numerical simulations, this technology has allowed us to observe molecular structure at the nano level, and consequently to quantify molecular motion.

Fig. 1: Molecular structure of toner material (grey: carbon, red: oxygen)

In determining the molecular structure of toner materials, Fuji Xerox employs molecular dynamics (MD). With this approach, based on the interaction between atoms (from which molecules are composed), it is possible to calculate how individual atoms will behave, and thus analyze the structure of molecules and their state of motion. These MD calculations enabled us to determine molecules' diffusion capabilities (to what degree molecules are free to move), and upon checking these against experiment results which determined the melting temperatures of three toner samples, a strong correlation between the two data sets was revealed. Furthermore, the results showed that Sample 1 melted more easily than either of the other two samples (Fig. 2).

Fig. 2: Relation between reciprocal of diffusion coefficient and melting temperature

Next, in order to examine the mechanisms at work, the diffusion capability of each monomer making up each of the three toner samples was calculated. The results showed that Sample 1, containing BPA (Bisphenol A), exhibited higher diffusion capability across all monomers, as well as more active molecular motion overall, when compared with Sample 2 and Sample 3. Not only has this simulation technology made it possible to observe molecular structure at the nano level and to quantify molecular motion, but furthermore, the relation found between molecular structures and melting characteristics will allow for future applications in the compositional engineering of toner materials with optimal melting properties.

Fig. 3: Diffusion coefficient of monomers making up toner samples (from left: Sample 1, Sample 2, Sample 3)