Toner Particles Research Articles

Electrostatic Charging of Fumed Silica Particles: Effect of Surface Treatment with Fluoroalkylsilanes

Hydrophobically modified fumed silica particles are widely used in toner formulations to enhance toner free flow and triboelectric charging. Despite the important role that dielectric powders have in electrophotography, the triboelectric charging of such powders is still poorly understood. In this article, the authors present experimental data on the charging properties of toners formulated with fumed silica additives that were modified with different levels of fluoroalkylsilanes. The results show that at high ambient relative humidity (RH) conditions, the triboelectric charge correlates with the fluorine content of the additive, whereas at low RH, the triboelectric charge is effectively constant with respect to fluorine content. The same result was obtained with two different types of toner particles. The authors attempt to rationalize these results in terms of surface conductivity at high RH conditions and charge saturation at low RH conditions. They also present a series of zeta potential measurements that show a correlation with tribocharge at high RH and interpret the results in terms of the ion-transfer model for triboelectric charging.

Distributions and ranges of values of blood and urinary biomarker of inflammation and oxidative stress in the workers engaged in office machine manufactures: evaluation of reference values

Interleukins, interferons and oxidative DNA products are important biomarkers assessing the inflammations and tissue damages caused by toxic materials in the body. We tried to evaluate distributions, reference values and age related changes of blood levels of inflammatory cytokines, C-reactive protein (CRP), IgE and urine levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG) among workers in a cohort study evaluating the health influences of toner particles. A total of 1366 male workers under age 50 years (age 19-49 years; 718 exposed and 648 not exposed to toner particles) in a cross sectional study of 1614 (categorized as 809 exposed and 805 not exposed, age 19-59 years) workers in a photocopier company has been followed prospectively as the cohort. Blood levels of interleukin (IL)-4, IL-6, IL-8, interferon-γ (IFN-γ), CRP, IgE and urine 8-OHdG were measured annually for 5 years. Reference values of the biomarkers are; CRP: 0.01-0.63×10(-2) g/L, IgE: 6-1480 IU/mL, IL-4: 2.6-76.1 pg/mL, IL-6: 0.4-4.9 pg/mL and 8-OHdG: 1.5-8.2 ng/mgCr. We could not evaluate reference values for IL-8 and IFN- γ because most of the values were below the sensitivity limits (2.0 pg/mL and 0.1 IU/mL, respectively). There were no differences of the biomarker levels between the toner exposed and the control workers. We observed a statistically significant age related decrease of serum IL-4 levels. This is the first report assessing the distributions and reference values of inflammatory biomarker levels in a large scaled cohort. We observed age related changes of some of the biomarkers. We could not detect any differences of the studied biomarker values between the toner exposed and the control workers.

Persistent Rocking Motion of Microparticles Under Acoustic Tone-Burst Base Excitation

In this work the rocking vibrational response of individual micro-spherical toner particles under a noncontact tone-burst (gated-harmonic) excitation was studied. An unexpected ringing motion which persisted for long periods of time with minimal damping was observed and reported. It was observed that a weak bond, as a result of suspected pure intermolecular (van der Waals) interactions, led to detectable natural frequencies and persistent rocking motion (ringing) observed while the response of a particle with a stronger bond followed closely the substrate surface motion without a relative vibrating motion. For toner particles with a mean diameter of 8.9 μm, a beat phenomenon vibrational behavior was also observed and reported at the tone-burst central frequency of 500 kHz, which was very close to the most dominant observed natural frequency of the particle’s rocking motion of 501.5 kHz. Strong natural frequencies of the rocking motion were observed in three groups lying in the range of 450–525 kHz. The associated work of adhesion for these three observed natural frequency groups was calculated and found to lie in the range between 65 and 82 mJ/m2. The ringing mechanism observed and reported here could lead to the development of a very accurate adhesion characterization technique for individual micro-particles. The approach involves no particle detachment and thus allows the studying of the effects of environmental changes on the same bond without bond breakage.

Surface Functionalization of Toner Particles for the Assembly of Three‐Dimensional Objects via Click Chemistry

AbstractIn diesem Artikel wird die Entwicklung von Polyacrylat‐Partikeln als potenzielles Tonermaterial für ein elektrophotographisches Rapid‐Prototyping‐Verfahren beschrieben, mit dessen Hilfe in Zukunft dreidimensionale Objekte aus verschiedenen Tonern aufgebaut werden können. Die Polyacrylat‐Partikel wurden an der Oberfläche funktionalisiert, um einen dreidimensionalen Aufbau mittels Klick‐Chemie zu ermöglichen.

Temperature Effects on Liquid Electrophoretic Inks

In liquid electrophotograpy inks are colloidal solutions of toner particles suspended in a dielectric liquid together with typically micellar toner charging components. Toner particles and charging agents are in physicochemical equilibrium with toner acquiring charge that may be temperature dependent. Viscous dissipative forces are primarily governed by carrier liquid viscosity which is also temperature dependent. Measurements of time dependent currents at high fields indicate that viscosity effects dominate temperature behaviour of Indigo electroinks.

The Effect of Carrier Surface Morphology on the Triboelectric and Imaging Performance of Insulative Two-Component Xerographic Developers

Xerography is based on the development of latent electrostatic images by triboelectrically-charged toner particles. In a two-component (TCD) developer, the toner particles are triboelectrically charged via energetic mixing with polymer-coated magnetic carrier beads. Since the TCD xerographic development process is non-linearly related to TCD developer properties (e.g. toner charge, toner supply, powder flow mechanics, etc.), TCD aging can be a major factor for eventual imaging failure. In this review, simple parametric models of triboelectric charging and xerographic development will be combined to illustrate some of the major effects of changes in carrier bead surface chemistry on insulative TCD xerographic development.

Formation of Charged Toner Layer and Degradation of Toner Particles in Doctoring Process of Electrophotographic Non-Magnetic Single-Component Development System

In a non-magnetic single-component development system in electrophotography, formation of a thin and uniform toner layer on the development roller is important for obtaining high image quality. We conducted experimental and numerical investigations to clarify the dynamics of toner particles in this process. Two approaches were adopted for the investigation. One is experimental and the other is numerical simulation using the distinct element method. We manufactured a mock-up apparatus consisting of a supply roller, a development roller, and a doctor blade for forming a thin toner layer on the development roller. The thickness, surface roughness, and charge density of the formed toner layer were measured after the doctoring process. It was clarified that the thickness of the toner layer was increased, but the charge density was decreased, by increasing the applied voltage and rotational speed. These findings were confirmed by direct observation of the toner motion in the doctoring area with a high-speed microscope camera. Numerical calculations performed using an improved distinct element method revealed that the elastic energy applied to the toner particles, which is an index of toner degradation, was increased by increasing the stiffness and pressing force of the doctor blade, but decreased when the curvature of the blade tip was large. The present experimental and numerical results can be used to improve non-magnetic single-component development system in electrophotography.

Parametric Investigation on Dynamics of Toner and Carrier Particles in Electrophotographic Two-Component Magnetic Brush Development System Using Direct Observation Technique and Numerical Simulation

Parametric Investigation on Dynamics of Toner and Carrier Particles in Electrophotographic Two-Component Magnetic Brush Development System Using Direct Observation Technique and Numerical Simulation

Powder and Film Charging Characteristic Estimation by the Standard Carrier of Imaging Society Japan

Two-component developers which consist of toners and carriers are widely used in modern electrostatic copying machines and laser printers which utilize electrophotographic printing process. Toner charge is essential in electrophotography. The toners are triboelectrically charged by the carriers when they come in to contact. Although there are several factors which come to effect in quality in electrophotography, control of adhesion of triboelectrically charged toner particles is crucial. As such the estimation of toner electrostatic properties is very important. ISJ (The Imaging Society Japan) has proposed the standard carriers with different charging abilities for estimating toner charging property as a standard method of measurement. The electrostatic surface potentials, when the films come in to contact with standard carriers are discussed. Further, Tungsten is used for film charging to understand the charging property. The contact is carried out as carriers and Tungsten beads are rolling on the film. It is confirmed that the standard carriers proposed by the committee of ISJ show same tendency in the film charging estimation as against standard toner. It is proposed that the standard carriers are useful to estimate the charging properties of various shape material.

Application of High-performance Computing Technique to Toner Particle Simulation based on Discrete Element Method

Application of High-performance Computing Technique to Toner Particle Simulation based on Discrete Element Method

Electron holography study of electric field variations

This paper presents a review of the recent electron holography studies on electric field variation that have been carried out using multifunctional specimen holders. In addition to the standard inner potential analysis, studies on electric field variations around field emission tips have been carried out. The electric field variations caused by ballistic emission in the case of a field emitter made of a TaSi(2) nanowire have been analyzed using electron holography. The charges and electric fields in electrophotographic materials such as toner particles and organic photoconductors have been quantitatively evaluated after equipping the specimen holder with a piezodriving probe to shield the specimens from electron irradiation. The conductivity and electric field variations in the case of Ag-based conductive adhesives have been analyzed by applying an electric current through the holder. Finally, the characteristic charging effect induced by electron irradiation in biological specimens has been studied. It has also been pointed out that under certain experimental conditions, the stationary orbits of electron-induced secondary electrons can be located by electric field visualization.

Characterization of Laser Printer Nanoparticle and VOC Emissions, Formation Mechanisms, and Strategies to Reduce Airborne Exposures

To better evaluate the health effects and indoor air quality impacts of nanoparticles generated by laser printers, measurements were made to characterize the number concentration, size distribution, morphology, and chemical composition of the emitted nanoparticles as a function of printer distance, idle time, “cold start” state, cartridge states, and number of pages printed. Emitted ion concentrations, nanoparticles, volatile organic compound (VOC) emissions, and toner particles were characterized using multiple analytical techniques. Finally, particle generation mechanisms and emission control strategies are discussed. Emission measurements were conducted using a commonly used black and white office printer (HP LaserJet4100) operating in a small (12 m2) office conference room environment and a stainless steel environmental chamber of similar size. Particle concentrations and size distributions were monitored using condensation particle counter (CPC) and scanning mobility particle sizer (SMPS) directly ab...

Preparation and Characterization of Magnetic Toner Particles by Direct Polymerization Method

In this study a kind of black toner, containing polymer, magnetic iron oxide pigment, and several other additives, was prepared by a suspension polymerization method. The morphology, influence factor of particle size, and glass transition of prepared toner were discussed. SEM image showed that the produced micron-sized particles have a spherical surface and the various chemicals were mixed into monomers during manufacturing of the particles. Discussion about particle formation and stability concluded that the toner particle size related with stabilizer concentration, stirrer speed, and crosslinking agent concentration. The bigger particles, resulted from droplets coalescence during polymerization process, disappeared when enough PVA stabilizer was used in the aqueous medium. .Increasing the stirrer speed corresponded to the decrease of the particles size. But any increase in stirrer speed t did not contribute to size reduction in small particles below 2μm. It was found that particle size decrease with the addition of crosslinking agent. The DSC result indicated the glass transition of polymerized toner could be effectively adjusted according to Fox equation through change the monomer ratio.

Characteristics of Development and Bead-Carry-Out Phenomena in Two-Component Electrophotographic Development System

The dynamics of toner and carrier particles in a two-component development system used in electrophotography were studied to clarify the development characteristics and to reduce the image defects due to the bead-carry-out (BCO) phenomenon. The height of the developed toner line image and the density of carrier particles adhered to the photoreceptor surface after development were measured and the behavior of the toner and carrier particles was observed using a high-speed microscope camera. This study clarifies that development occurs not only in the contact area between the carrier brush and the photoreceptor but also in the pre- and postnip regions where the brush does not make contact with the photoreceptor and that the occurrence of BCO is reduced in the image area rather than in the nonimage area at a low dc development voltage at a high toner concentration and with the development sleeve at a high-speed ratio. The mechanisms of these phenomena are investigated using independent experimental and numerical analysis.

Preparation of Chemically Prepared Toners (CPT) by Polymerisation for Ceramic Decoration

In ceramics decoration by xerography, once the toner particles have been deposited, the substrates need to be subjected to thermal treatment at temperatures above 400 °C to eliminate the organic constituents in the toner and enable the inorganic constituents to be integrated into the ceramic surface. The inorganic component includes an active inorganic fraction in decoration that is able to modify the aesthetic appearance of the surface to be coated, and an inorganic fraction that facilitates fusibility and integration into the substrate.At present, this type of toner is made by the pulverisation method, with the presence of irregularly-shaped particles and inorganic particles that are only partly coated by the plastic organic matrix, which can lead to problems of particle flowability and electrical conductivity.This paper describes a new method of ceramic toner preparation by suspension polymerisation that avoids the above problems. The method allows a high inorganic component content in the toner composition to be reached, assuring good colour saturation in decoration.

C-2-2 電子写真の非磁性1成分現像系におけるトナー層のドクタープロセス(C-2 柔軟媒体ハンドリング/画像形成機器2,口頭発表:柔軟媒体ハンドリング/画像形成機器)

In a non-magnetic single-component development system in electrophotography, formation of a thin and uniform toner layer on the development roller is important for obtaining high image quality. We conducted experimental and numerical investigations to clarify the dynamics of toner particles in this process. Two approaches were adopted for the investigation. One is experimental and the other is numerical simulation using the distinct element method. We manufactured a mock-up apparatus consisting of a supply roller, a development roller, and a doctor blade for forming a thin toner layer on the development roller. The thickness, surface roughness, and charge density of the formed toner layer were measured after the doctoring process. It was clarified that the thickness of the toner layer was increased, but the charge density was decreased, by increasing the applied voltage and rotational speed. These findings were confirmed by direct observation of the toner motion in the doctoring area with a high-speed microscope camera. Numerical calculations performed using an improved distinct element method revealed that the elastic energy applied to the toner particles, which is an index of toner degradation, was increased by increasing the stiffness and pressing force of the doctor blade, but decreased when the curvature of the blade tip was large. The present experimental and numerical results can be used to improve non-magnetic single-component development system in electrophotography.

Model of Toner Impaction and Developer Failure

High definition digital imaging is enabled in printers by using small micron and nano toner particles. Use of small particles in a housing presents challenges in particle flow as small particles tend to aggregate, clog and impact either on the wall of the housing or on other surfaces. Solids are known to undergo brittle-ductile transition depending on the size of a particle, elastic plastic behavior and strain rates under which they are deformed.In macromolecules, polymer chain flexibility and shear flow of uniformly sized, spherical particles can be analyzed. Inter-particle attractive forces are considered to influence flow of small particles. Simulations performed for different strengths of cohesion, shear rates, particle stiffnesses, particle volume fractions and coefficients of friction show interesting results. From each simulation, the average normal and shear stresses and the average coordination number have been extracted. Generally small particles are externally mixed with nano-sized particles to improve flow. Hard nano-sized particles reduce cohesiveness of toner particles and reduce its aggregation.Particulate flow can some time result in jamming and has been analyzed using Lattice-Boltzmann (LB) or DEM (Discrete Element Methods) involving deformation from collisions resulting from hydrodynamic forces. Consequence of particle impaction on surfaces is a reduction in particle charge with wider distribution causing shortfalls in electro-photographic development and image quality. A rate equation model is developed for impaction in a cylindrical cavity that depends on the impact parameter, rate of volumetric flow, yield stress (modulus) of the elastic-plastic particle, size of the particle and dynamic coefficient of friction. The model predictions are compared with experimental data on the particle (toner) impaction

The Research of Process and Characteristic of Pulverized Rounding Surface Treated Toner

The purpose of this study is to research into the relationships between the characteristics of the pulverized rounding surface treated toner (RST Toner) and various surface treatments, BET values and quantities of surface additives. The surface additives with different surface treatments including DDS, HMDS and PDMS are used in this study as the spacer between toner particles before the rounding surface treatment process. In this study, the surface fusion system is used to prepare the RST toner with the circularity about 0.970.

Numerical Simulation on Dynamics of Toner and Carrier Particles in Two-Component Magnetic Brush Development System in Electrophotography

Numerical Simulation on Dynamics of Toner and Carrier Particles in Two-Component Magnetic Brush Development System in Electrophotography

Non-spherical Toner Behavior Simulation by Polyhedral Particle

The shape of toner particles has a significant influence on the imaging performance in the electro-photographic process. In this study, we developed a program that calculates the toner behavior as we considered every particle shape. The program uses a distinct element method using polyhedral particles. We developed algorithms that classify the contact of the particle into four patterns depending upon the tangency of the vertex, the edge and the face of polyhedron. Utilizing the developed program, we calculated how the toner scatters by creeping discharge. Furthermore, we investigated the reason why a sphere toner scatters more intensely than non-sphere toner. As a result, we found that the difference between toner's shapes and adhesive properties in terms of their motion flexibility determines the scattering performance.