Toner external additive for controlling charge amount, and toner using same

Abstract

The present invention relates to a toner external additive having SnO2 attached to the surface of SiO2 particles, or a toner external additive obtained by coating a SiO2 core with SnO2 as a shell, and then surface-treating same. Since the charge amount of silica is high, SnO2 is added to reduce the charge amount and prevent aggregation between particles such that the toner can be uniformly coated, and thus fluidity and heat retention can be improved.

Description

Toner additive for controlling charge and toner using the same

[0001] The present invention relates to a toner external additive for controlling charge and a toner using the same.

[0002] With the recent advancements in personal computers and the proliferation of networks, digital color copiers and printers, which serve as output devices for information network systems, are increasingly demanding higher image quality, increased productivity, and higher reliability. Consequently, the market for on-demand printing is growing rapidly. Furthermore, we face challenges such as global warming and the depletion of energy and resources, and companies are increasingly required to demonstrate a sense of responsibility and contribute to society in the pursuit of a sustainable society. Therefore, it is necessary to reduce the environmental impact of wasteful resources and energy, regardless of whether it is during manufacturing or use.

[0003] In this situation, toners are also required to have small particle sizes and narrow particle size distributions for high image quality, vivid color development, reduced energy consumption, and the ability to fix at lower temperatures for improved productivity. The present invention relates to a toner external additive for controlling charge and a toner using the same.

[0004] As toner particles become smaller, the size of external additives, such as silicon dioxide, titanium dioxide, aluminum oxide, and zinc oxide, is also decreasing, and their use is steadily increasing. Consequently, the use of nano-sized titanium dioxide, which has been controversial for its toxicity, could negatively impact workers in related industries as well as general consumers.

[0005] In particular, in order to respond to the recent trend toward full color, high speed, and high image quality of printers, as well as the trend toward miniaturization (light weight) and eco-friendliness, the shape and surface control technology of toner is becoming increasingly important in order to satisfy the physical properties of toner required for the electrophotographic process.

[0006] For example, because the number of times the toner receives shear force from external materials increases due to high speed, a toner design with high durability is required, and to reduce the amount of residual toner after transfer in order to miniaturize and become environmentally friendly, a toner surface treatment technology is required to increase the uniformity of toner charge and improve transfer efficiency.

[0007] To enhance charge stability, transfer efficiency, and cleanability, the selection of an external additive that applies appropriate inorganic particles to the surface is crucial. External additives impart fluidity to the resin particles, improving toner supply and adhering to the toner surface, providing stable charge performance. They also significantly impact cleanability by reducing the surface adhesion of the electrostatic latent image carrier, facilitating the easy removal of residual toner.

[0008] However, inorganic fine particles used as conventional surface treatment agents have difficulty ensuring such uniformity of charge. For example, the commonly used fumed silica-based inorganic fine particles have a strong negative polarity, making them prone to charge-up. To prevent this excessive triboelectric charging, titanium oxide inorganic fine particles are often added. However, titanium oxide has low electrical resistance and good charge exchange properties, making it relatively easy to produce negatively or weakly charged toners, which hinders uniformity of charge. In particular, when silica inorganic fine particles are added, the more porous the silica structure and the more hydrophilic the surface, the more excessively high the chargeability of the negatively charged toner at low temperature and low humidity. On the other hand, at high temperature and high humidity, moisture acts as a kind of conductor, so the more moisture is absorbed, the less chargeability there is, resulting in poor concentration reproducibility, such as a rapid increase in concentration at high temperature and high humidity, and background contamination. In addition, this can cause image stains due to electrostatic effects at low temperature and low humidity.

[0009] Therefore, to solve this environmental charge stability problem, silica or titanium dioxide whose surface has been treated with hydrophobic silicone oil or silica coupling agent is generally used. However, the surface treatment causes the fine particles to coagulate strongly, which reduces the dispersibility of the toner or causes fluidity or blocking. In particular, in the case of the fumed type silica used in the past, silica aggregation often occurs during the manufacturing process, which reduces the performance of the inorganic fine particles. When the dispersibility of these inorganic fine particles is poor, fluidity, caking resistance, and fixation are poor, which often leads to poor toner supply or reduced fixation. In addition, when the silica fine particles aggregate, the cleanability is also reduced, which causes problems such as filming in which the fine particles adhere to the electrostatic latent image carrier or contaminating the charge roller, causing uneven charging of the electrostatic latent image carrier and reduced fixation.

[0010] The purpose of the present invention is to manufacture a toner external additive capable of improving fluidity and heat preservation by reducing the charge and preventing agglomeration between particles through the content of SnO2, thereby enabling uniform coating on the toner.

[0011] The present invention is characterized by a toner additive characterized by attaching SnO2 to the surface of SiO2 particles or a toner additive characterized by coating SnO2 as a shell on a SiO2 core and then performing surface treatment. Accordingly, it has the effect of improving coagulation by minimizing particle coagulation, improving fluidity, and enhancing heat preservation.

[0012] The above silica particles are a toner external additive that are monodisperse spherical particles with a diameter of 30 nm to 200 nm, and preferably, the silica particles are characterized by being monodisperse spherical particles with a diameter of 50 nm to 150 nm.

[0013] In addition, the SnO2 particles are characterized as fine particles of 3 to 20 nm.

[0014] The SnO2 coating amount on the SiO2 particles is characterized by being 0.1 to 50 wt% of the total particles, and preferably, the SnO2 coating amount is characterized by being 5 to 20 wt% of the total particles.

[0015] Since silica has a high charge, the content of SnO2 reduces the charge and prevents agglomeration between particles, enabling uniform coating on the toner, thereby improving fluidity and heat preservation.

[0016] Figure 1 is a cross-section of a particle in which SnO2 is attached to the surface of a SiO2 particle.

[0017] Figure 2 is a cross-section of a particle using SiO2 as a core and coating SnO2 as a shell.

[0018] Figure 3 is a photograph showing the shape of the particles of the present invention.

[0019] The present invention is characterized by a toner additive characterized by attaching SnO2 to the surface of SiO2 particles or a toner additive characterized by coating SnO2 as a shell on a SiO2 core and then performing surface treatment. Accordingly, it has the effect of improving coagulation by minimizing particle coagulation, improving fluidity, and enhancing heat preservation.

[0020] The above silica particles are a toner external additive that are monodisperse spherical particles with a diameter of 30 nm to 200 nm, and preferably, the silica particles are characterized by being monodisperse spherical particles with a diameter of 50 nm to 150 nm.

[0021] In addition, the SnO2 particles are characterized as fine particles of 3 to 20 nm.

[0022] The amount of SnO2 coating on the SiO2 particles is characterized by being 0.1 to 50 wt% of the total particles, and preferably, the amount of SnO2 coating is characterized by being 5 to 20 wt% of the total particles. To help understand the invention, preferred examples are presented. However, the following examples are provided only to more easily understand the invention, and the content of the present invention is not limited by the examples.

[0023]

[0024] Example

[0025] 1. Preparation of nano silica particles by sol-gel method

[0026] The sol-gel method using the Stober method is widely used for the production of monodisperse silica. The Stober method involves a condensation reaction between alkyl silicate and silicic acid in the presence of alcohol, using an ammonia catalyst. The particle diameter of silica is determined through the nucleation and growth processes, and the final particle diameter and particle size distribution of the hydrolysis and condensation reactions are determined by the type of precursor, alcohol, ammonia, reaction temperature, and reaction time.

[0027] During the hydrolysis process, the ethoxy group of TEOS (tetraethoxysilane) reacts with water molecules to form an intermediate of Si(OC2H5)4-X(OH)X. Ammonia acts as a basic catalyst and attacks the OH anion of the TEOS molecule, causing hydrolysis to proceed. The chemical reaction can be expressed as follows.

[0028] Si(OC2H5)4+xH20 --> Si(OC2H5)4-X(OH)X+XC2H5OH

[0029] After this reaction, the condensation reaction proceeds immediately and is expressed by the following chemical equation.

[0030] Si(OC2H5)4+ 2H2O --> SiO2+ 4C2H5OH

[0031] TEOS (98% purity) used in the experiment was purchased from Fisher Company, and 31.5% of ammonium hydroxide was purchased from Aldrich Company.

[0032] For the above experiment, TEOS was prepared at 0.2 M, NH3 at 0.2 M, and H2O at 1 M to produce spherical silica particles of approximately 100 nm. After the particles were produced, the silica colloid solution was centrifuged to remove the supernatant, and the remaining silica slurry was washed with ethanol to remove impurities and then dried at 100°C for 2 hours.

[0033]

[0034] 2. Synthesis of composite tin oxide particles and hydrophobic coating

[0035] (1) Weigh sodium tartrate (Na2SnO3) to 1 mol / L and sodium aluminate (NaAlO2) to 0.01 mol / L, then slowly add sodium tartrate (Na2SnO3) powder and sodium aluminate to pure water and use a stirrer to dissolve well. At this time, the temperature of the pure water was adjusted to approximately 60℃.

[0036] (2) Slowly add 1 mol / L nitric acid (HNO3) prepared in advance to the mixed solution of sodium tartrate and sodium aluminate obtained in (1) to finally adjust the pH of the entire solution to 3 to 3.5.

[0037] (3) Afterwards, the obtained aluminum hydroxide (Al(OH)3)-tin hydroxide (Sn(OH)4) composite hydroxide is obtained, and all unnecessary ionic species are removed using pure water and ethyl alcohol.

[0038] (4) The resulting composite material is placed in a convection dryer and dried at 60°C for 24 hours.

[0039] (5) Fine particles of aluminum(III) hydroxide-tin(IV) hydroxide composite oxide having a specific surface area of ​​110 m2 / g were synthesized by heat-treating the dried aluminum(III) hydroxide-tin(IV) hydroxide composite oxide at 300°C for 2 hours.

[0040] (6) (5) Hydrophobic aluminum(III) oxide-tin(IV) oxide composite oxide nano-sized particles obtained in the process were coated with dimethyldimethoxysilane, hexamethyldisilazane, decyltrimethoxysilane, etc. to obtain hydrophobic aluminum(III) oxide-tin(IV) oxide composite oxide nano-sized particles.

[0041]

[0042] 3. Manufacturing of toner additives

[0043] In the present invention, SnO2 was attached to the surface of SiO2 particles. (Fig. 1)

[0044] The silica particles are monodisperse spherical particles with a diameter of 30 nm to 200 nm, and preferably, the silica particles are monodisperse spherical particles with a diameter of 50 nm to 150 nm. The SnO2 particles are fine particles with a diameter of 3 nm to 20 nm.

[0045] The SnO2 coating amount on the SiO2 particles is characterized by being 0.1 to 50 wt% of the total particles, and preferably, the SnO2 coating amount is characterized by being 5 to 20 wt% of the total particles.

[0046] Meanwhile, SnO2 was coated as a shell on the SiO2Core and then surface treated. (Fig. 2)

[0047] The silica particles are monodisperse spherical particles with a diameter of 30 nm to 200 nm, and preferably, the silica particles are monodisperse spherical particles with a diameter of 50 nm to 150 nm. The SnO2 particles are fine particles with a diameter of 3 nm to 20 nm. In addition, the SnO2 particles are fine particles with a diameter of 3 nm to 20 nm.

[0048] The SnO2 coating amount on the SiO2 particles is characterized by being 0.1 to 50 wt% of the total particles, and preferably, the SnO2 coating amount is characterized by being 5 to 20 wt% of the total particles.

[0049] In this way, by positioning SnO2 on the surface of SiO2 particles, agglomeration of the entire particles is minimized, which improves agglomeration and has the effect of improving fluidity and heat preservation.

Claims

1. A toner external additive characterized by attaching SnO2 to the surface of SiO2 particles.

2. A toner external additive characterized by coating SnO2 as a shell on SiO2 Core and then performing surface treatment.

3. In paragraph 1 or 2, The above SiO2 particles are toner external additives that are monodisperse spherical particles with a diameter of 30 nm to 200 nm.

4. In paragraph 3, The above SiO2 particles are toner external additives that are monodisperse spherical particles with a diameter of 50 to 150 nm.

5. In paragraph 1 or 2, The above SnO2 particles are toner additives that are fine particles of 3 to 20 nm.

6. In paragraph 1 or 2, A toner external additive characterized in that the SnO2 coating amount on the SiO2 particles is 0.1 to 50 wt% of the total particles.

7. In paragraph 6, A toner external additive characterized in that the SnO2 coating amount is 5 to 20 wt% of the total particles.

8. Toner containing the toner additive of paragraph 1 or 2.

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