Toner is a main component of electrophotographic printing and copying processes. One of the most important ingredients of toner is magnetite (Fe3O4) which provides the tribocharging property for toner particles. In this study, nano- and microparticles of Fe3O4 were synthesized using the coprecipitation method and different amounts of lauric acid as a surfactant. The synthesized nano and micro Fe3O4 was then used as the charge control agent to produce toner by emulsion aggregation. The Fe3O4 and toner were characterized by X-ray powder diffraction (XRD), atomic gradient force magnetometry (AGFM), dynamic laser scattering (DLS), particle size analysis, differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). The results show that the optimum amount of surfactant not only reduced particle size but also reduced the magnetite properties of Fe3O4. It was found that the magnetite behavior of the toner is not similar to the Fe3O4 used to produce it. Although small-sized Fe3O4 created toner with a smaller size, toners made with micro Fe3O4 showed better magnetite properties than toner made with nano Fe3O4.
Toner is a composite powder that contains polymer, pigment, magnetite, and additives which is used for electrophotography (EP) printing. In the last two decades, EP has become a legitimate alternative to analog print production technologies [
The application of electrophotography varies from manufacturer to manufacturer, but the basic principle is the same. Initially, a photoconductive belt or roller is uniformly charged. Next, the image area is selectively discharged, usually by a laser. Subsequently, toner is brought into contact with the photoreceptor. Upon contact with the photoreceptor, toner particles attach to the discharged image areas of the photoreceptor. This toner image is then transferred to the substrate, where it is bonded using heat and pressure. Finally, the photoreceptor is cleaned of residual charges and toner in preparation for the next image (see Figure S1 in the Supplementary Material available online at
As previously mentioned, toner is manufactured by combining polymer, pigment, magnetite, and additives. The resulting mass is extruded and mechanically ground to produce toner particles small enough for use in electrophotography [
One solution to this is the use of chemically prepared toner (CPT). Unlike mechanical milling, CPT toner is synthesized from nanometer-sized particles using one of several chemical processes, such as suspension polymerization [
Technically, the printing mechanism in electrophotography requires the toner to be magnetic [
Nanosized materials have many modern applications, although macrosized materials also have advantages, like ease of production [
The one-step coprecipitation process is a predominant method of producing nano- and micromagnetite because only two chemicals are needed and production costs are lower. Few researches has focused on the controlled synthesis [
The aim of this study is to control the size of the Fe3O4 particles, from nano- to microsized, using one-step coprecipitation method with different amounts of surfactant and compares the effect of size on the properties of printing toners produced via EA methods.
Ferrous chloride (FeCl2·4H2O), ferric chloride (FeCl3·6H2O), ammonia, and lauric acid were purchased from Merck and used without further purification. The polymer used in this study was a styrene-acrylic resin (NS88; Simab Resin Co., Tehran). A polyethylene emulsion wax (EE 95, Kala Kar Co., Tehran) and a carbon black pigment (Printex U, Degussa-Evonik, Germany) were also used in the experiments. Polyaluminum chloride was used as a coagulation agent.
The coprecipitation method was used to synthesize Fe3O4 nanoparticles. The process for the Fe3O4 nucleation from a salt solution occurs in the reaction [
The defined experimental sets for Fe3O4 particles synthesize with variations in lauric acid amount and defined experimental sets for toner synthesize with various types of Fe3O4 particles.
Magnetite sample | Surfactant concentration (gr/lit) | Magnetite colloidal appearance |
---|---|---|
M0 | 0 | Unstable |
M1 | 54 | Semistable |
M2 | 108 | Stable |
M3 | 218 | Stable |
M4 | 434 | Un-stable |
All toners in this study were prepared using the following procedure [
A gel was formed during this process and the viscosity of the suspension changed dramatically from an initially Newtonian, water-like fluid to a very shear thinning, paste-like gel. The temperature of the mixture was then raised to 50°C within 30 min, while the gel was mixed and was held at this temperature for another 60 min. Then, the temperature of the mixture was raised to 96°C within 30 min and held at this temperature for further 60 min. The mixture was neutralized using a sodium hydroxide solution after raising the temperature. Finally, the mixture was cooled to 25°C, after which the produced microparticles were isolated from the liquid, washed to remove divalent ions, filtered, and dried (see Figure S2). The Fe3O4 particles synthesized as described above were used to explore the effect of Fe3O4 particle size on toner properties.
The dried powder samples of magnetite nanoparticles were characterized using an X-ray powder diffractometer (XRD) with Cu-K
The size and size distribution of the toner particles were determined using a Particle Size Analyzer (PSA, Mastersizer2000, Malvern, UK). Evaluation of the particle size distribution was done using the span parameter:
A melting point meter (Buchi, Switzerland) and a differential scanning calorimeter (Pyris 6, Perkin Elmer, Germany) were employed to investigate the thermal behavior of the toner. Scanning Electron Microscopy (SEM, KYKY-EM3200, China) was utilized to investigate the shape and morphology of the toner particles. The saturation magnetization was measured using the above-mentioned AGFM at room temperature.
The XRD pattern of the precipitate is shown in Figure
The XRD pattern of the synthesize Fe3O4 particles with various amounts of surfactant.
This phase formation may be related to the aggregation oxygen adsorption and the conditions of production, such as pH and concentration surfactant [
TEM result for M3 sample can be seen in Figure
TEM images of Fe3O4 particles (M3).
Figure
The average crystal size of synthesize Fe3O4 particles with various amounts of surfactant by Sherrer’s equation.
The average particle size of synthesize Fe3O4 particles with various amounts of surfactant.
Figure
Magnetite properties of synthesize Fe3O4 particles with various amounts of surfactant.
Magnetite saturation of synthesize Fe3O4 particles with various amounts of surfactant.
The effects of magnetite size change from nano to macro on toner structural properties were tested in different sets. The particle size and particle size distribution (span) of the toner particles are shown in Table
Particle size, glass transition temperature, and softening point of synthesize toner samples.
Toner sample | Particle size ( |
Span | Glass transition temperature (°C) | Softening point (°C) |
---|---|---|---|---|
TM0 | 9 | 1.75 | 51.25 | 134 |
TM1 | 7.2 | 1.40 | 51.36 | 135 |
TM2 | 6.9 | 0.95 | 51.31 | 130 |
TM3 | 6.2 | 0.87 | 53.22 | 131 |
TM4 | 13 | 1.95 | 52.78 | 132 |
The particle shape of the toner depended on the aggregation temperature and the glass transition temperature (
SEM images of toner synthesize with various types of Fe3O4 particles.
The thermal characteristics of the toner, especially
Table
Figure
Magnetite properties of toner synthesize with various types of Fe3O4 particles.
Figure
Magnetite saturation of toner synthesize with various types of Fe3O4 particles.
This study investigated the synthesis of Fe3O4 particles by coprecipitation with a focus on the effect of surfactant on the formation of Fe3O4 nano- and macroparticles. XRD revealed that the assynthesized particles were either
The authors declare that there is no conflict of interests regarding the publication of this paper.