JPH04217267A - Electrostatic charge image developing toner - Google Patents

Abstract

PURPOSE:To obtain an electrostatic charge image developing toner possible to obtain many sheets of copies by eliminating problems of picture density decrease, ground fogging increase and improper gradient with no influence by environmental characteristic. CONSTITUTION:A fluidity improver of -10 to +10mV ZETA potential in hydrogen ion concentration pH of 5 adheres by 0.1 to 0.6 weight to a surface of a toner grain. A surface of metal oxide of SiO2, TiO2, SnO, ZnO, Al2O3, etc., which is concretely a normal fluidizer, is processed and coated by using a coupling processor so that the fluidity improver of predetermined ZETA potential is obtained. As the coupling processor, methyl trimethoxysilane, (3-aminopropyl) trimethoxysilane, etc., are used.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chargeable toner for developing electrical latent images in electrophotography, electrostatic recording, and the like.

0002

[Prior Art] Conventionally, toner for developing electrostatic images used in electrophotography needs to have fluidity due to its nature, and for this purpose, one or more fluidizing agents are added to the surface of the toner. The toner is developed in combination with iron powder or ferrite carrier to maintain the optimum amount of charge required for the phenomenon.

0003

[Problem to be solved by the invention] So far, silica, titanium oxide, etc. have been used as the fluidizing agent used here, but these fluidizing agents themselves have no charge Due to this, the amount of charge that the toner originally has is inhibited, causing fogging, decreased density, and poor gradation during development. This results in defects such as shortened agent life.

[0004] Furthermore, when a fluidizing agent is used, the environmental characteristics of the toner are such that in high temperature and high humidity, the toner scatters as the amount of charge decreases due to moisture absorption, causing problems such as increased fog. At low temperatures and low humidity, there are problems such as a decrease in image density (ID) and filming due to an increase in the amount of charge.

[0005] The present invention solves the above-mentioned problems, and is capable of producing a large number of copies without being affected by environmental characteristics, without problems such as a decrease in image density, an increase in background fog, or poor gradation. The purpose of the present invention is to provide a toner for image development.

[0006]

[Means for Solving the Problems] The present invention has been made as a result of extensive research in view of the above-mentioned circumstances, and it aims to change the zeta potential of a fluidity improver at a hydrogen ion concentration pH of 5.
The present invention relates to a toner for developing an electrostatic image in which 0.1 to 0.6% by weight of -10 to +10 mV is attached to the surface of toner particles.

Specifically, SiO2, which is a common flow agent,
, TiO2, SnO, ZnO, Al2O
A fluidity improver having a predetermined zeta potential can be obtained by treating and coating the surface of a metal oxide such as No. 3 with the following coupling treatment agent.

Coupling agent: methyltrimethoxysilane, (3-aminopropyl)trimethoxysilane,
(3-aminopropyl)triethoxysilane, {3-(
2-aminoethoxyamino)propyl}triethoxysilane, {3-(2-aminoethoxyamino)propyl}
trimethoxysilane etc.

[0009] Generally, the coupling agent has an amino group so that the zeta potential of the fluidity improver can be adjusted to the positive side. In this way, the zeta potential can be easily controlled by introducing various functional groups. The coupling treatment method is a general gas phase method. The electrostatic charge image developing toner in which the fluidity improver of the present invention is attached to the particle surface has no significant difference in the amount of charge under a low-temperature, low-humidity environment or a high-temperature, high-humidity environment from that under a normal temperature and normal humidity environment. Therefore, a stable image with no difference in image density, BG fog (background fog in non-image areas), gradation, toner scattering, etc. can be obtained.

0010

[Function] When a fluidity improver with a zeta potential of less than -10 mV is used in a negatively charged toner, the amount of triboelectric charge increases during copying under normal temperature and normal humidity environments, and low temperature and low humidity environments, resulting in a decrease in image density. bring about. Furthermore, in a high temperature and high humidity environment, the amount of frictional charge decreases and background fog increases. On the other hand, when used in a positively chargeable toner, the triboelectric charge amount decreases in a high temperature and high humidity environment, resulting in a decrease in image density and poor gradation.

On the other hand, when a fluidity improver with a zeta potential of more than +10 mV is used in a negatively chargeable toner, the amount of triboelectric charge decreases in a high temperature and high humidity environment, resulting in a decrease in image density and poor gradation. bring. On the other hand, when used in a positively chargeable toner, the amount of triboelectric charge increases during copying under normal temperature and normal humidity environments and low temperature and low humidity environments, resulting in a decrease in image density. Furthermore, in a high temperature and high humidity environment, the amount of frictional charge decreases and background fog increases. Therefore, in the present invention, the zeta potential is selected to be -10 to +10 mV.

The toner particles of the present invention are prepared by mixing a binder resin, a charge control agent, a colorant, and other additives as necessary in a desired range, melting and kneading the mixture, cooling it, solidifying it, and then crushing and classifying it. can be obtained.

As the above-mentioned binder resin, those generally used as binder resins for toners can be used, such as styrene resin, polyacrylate resin, styrene-acrylate copolymer resin, and vinyl chloride. resin, vinyl acetate resin, vinylidene chloride resin, phenol resin, epoxy resin, polyester resin, etc. Furthermore, as the colorant, those commonly used as colorants for toners can be used, such as carbon black, monoazo red pigments, disazo yellow pigments, quinacridin magenta pigments, anthraquinone dyes, etc. It will be done.

Furthermore, as charge control agents, nigrosine dyes, alkoxy amines, quaternary ammonium salts, metal complex salts of monoazo dyes that provide negative chargeability, and electron-accepting organic complexes that provide negative chargeability are used. , polyester with excess acid groups, and the like.

Other additives that may be added as necessary include, for example, polystyrene or polyacrylic resin powder,
Examples include powders of titanium dioxide, conductive titanium, and zinc, and lubricants such as metal salts of higher fatty acids.

In the present invention, as a means for attaching the fluidity improver to the surface of the toner particles, general stirring machines such as a paddle-type stirrer, a turbine-type stirrer, and a Henschel mixer can be used.

Other surface modifying machines such as Ong Mill manufactured by Hosokawa Micron Co., Ltd. and Hybridizer manufactured by Nara Kikai Seisakusho Co., Ltd. may also be used.

In the present invention, the amount of the fluidity improver attached to the surface of the toner particles is 0.1 to 0.0% relative to the toner.
It is 6% by weight. If it is less than 0.1% by weight, no improvement in fluidity will be observed, and if it is more than 0.6% by weight, it will affect the triboelectric charging properties with toner particles and cause problems.

When developing using the toner for an electrostatic image developer of the present invention, magnetic powder may be added to the toner particles to form a one-component developer, or it may be mixed with an iron powder carrier, a ferrite carrier, etc. A two-component developer may also be used. In this case, silicone-coated ferrite carrier is preferable in order to maintain the life of the developer for a long time, and in order to obtain high image quality,
The carrier current value of the silicone coated ferrite carrier is preferably 0.2 to 0.8 μA.

[0020]

EXAMPLES Examples of toner formulations according to examples of the present invention and evaluation of toner characteristics based on the formulations will be described below.

The method for producing the toner is as follows. A toner was prepared by kneading and pulverizing the above formulation.

The particle size distribution in this case is as follows. The fluidity improver is fixed on the toner by stirring for a certain period of time using a 10 liter or 20 liter Henschel mixer.

The toner characteristic evaluation test was carried out as follows. I did it. (2) Life test was conducted on Toshiba Co., Ltd. copy machine RheoDry BD-3
810 was used. The characteristic values shown in the examples are ID,
These are BG, charge amount, and gradation. For gradation, we used a Kodak gray scale chart (manufactured by Kodak).
The number of stages that allows visual judgment of the 0-stage halftone is shown. The amount of charge was measured using a blow-off charge amount measuring device manufactured by Toshiba Chemical Corporation.

[0024]

[Example 1] After mixing 3 g (0.3%) of silica with a zeta potential of -4 mV at pH = 5.0 to 1 kg of the above toner,
It was deposited using a Henschel mixer with a capacity of 10 liters under conditions of rotation speed of 3000 rpm and stirring for 2 minutes.
A developer was prepared by combining this toner with a silicon-coated ferrite carrier having a carrier current value of 0.5 μA, and a life test was conducted.

[0025]

[Example 2] After mixing 3 g of silica with a zeta potential of -6 mV at pH = 5.0 to 1 kg of the above toner, the mixture was mixed with a 10 liter Henschel mixer at a rotational speed of 3000 r.
pm and stirring for 2 minutes. A developer was prepared by combining this toner with a silicon-coated ferrite carrier having a carrier current value of 0.5 μA, and a life test was conducted.

[0026]

[Example 3] After mixing 3 g of silica with a zeta potential of -9 mV at pH = 5.0 to 1 kg of the above toner, the mixture was mixed with a 10 liter Henschel mixer at a rotational speed of 3000 r.
pm and stirring for 2 minutes. A developer was prepared by combining this toner with a silicon-coated ferrite carrier having a carrier current value of 0.5 μA, and a life test was conducted.

[0027]

[Example 4] After mixing 3 g of silica with a zeta potential of +2 mV at pH = 5.0 to 1 kg of the above toner, the mixture was mixed with a 10-liter Henschel mixer at a rotational speed of 3000 r.
pm and stirring for 2 minutes. A developer was prepared by combining this toner with a silicon-coated ferrite carrier having a carrier current value of 0.3 μA, and a life test was conducted.

[0028]

[Example 5] After mixing 3 g of silica with a zeta potential of +6 mV at pH = 5.0 to 1 kg of the above toner, the mixture was mixed with a 10-liter Henschel mixer at a rotational speed of 3000 r.
pm and stirring for 2 minutes. A developer was prepared by combining this toner with a silicon-coated ferrite carrier having a carrier current value of 0.3 μA, and a life test was conducted.

[0029]

[Example 6] After mixing 3 g of silica with a zeta potential of +8 mV at pH = 5.0 to 1 kg of the above toner, the mixture was mixed with a 10-liter Henschel mixer at a rotational speed of 3000 r.
pm and stirring for 2 minutes. A developer was prepared by combining this toner with a silicon-coated ferrite carrier having a carrier current value of 0.3 μA, and a life test was conducted.

[0030]

[Example 7] After premixing 1 kg of the above toner with 2 g of silica having a zeta potential of -5 mV at pH = 5.0, the mixture was mixed with 1 kg of the above toner and then mixed with a 10 liter Henschel mixer at a rotation speed of 3000.
It was deposited under the conditions of stirring at rpm for 2 minutes. A developer was prepared by combining this toner with a silicon-coated ferrite carrier having a carrier current value of 0.5 μA, and a life test was conducted.

[0031]

[Example 8] After mixing 4 g of silica with a zeta potential of -5 mV at pH = 5.0 to 1 kg of the above toner, the mixture was mixed with a 10 liter Henschel mixer at a rotational speed of 3000 r.
pm and stirring for 2 minutes. A developer was prepared by combining this toner with a silicon-coated ferrite carrier having a carrier current value of 0.5 μA, and a life test was conducted.

[0032]

[Example 9] After mixing 6 g of silica with a zeta potential of -5 mV at pH = 5.0 to 1 kg of the above toner, the mixture was mixed with a 10-liter Henschel mixer at a rotation speed of 3000 r.
pm and stirring for 2 minutes. A developer was prepared by combining this toner with a silicon-coated ferrite carrier having a carrier current value of 0.5 μA, and a life test was conducted.

[0033]

[Example 10] After mixing 2 g of silica with a zeta potential of +5 mV at pH = 5.0 to 1 kg of the above toner, the mixture was mixed with a 10 liter Henschel mixer at a rotation speed of 3000.
It was deposited under the conditions of stirring at rpm for 2 minutes. A developer was prepared by combining this toner with a silicon-coated ferrite carrier having a carrier current value of 0.5 μA, and a life test was conducted.

[0034]

[Example 11] After mixing 4 g of silica with a zeta potential of +5 mV at pH = 5.0 to 1 kg of the above toner, the mixture was mixed with a 10 liter Henschel mixer at a rotation speed of 3000.
It was deposited under the conditions of stirring at rpm for 2 minutes. A developer was prepared by combining this toner with a silicon-coated ferrite carrier having a carrier current value of 0.5 μA, and a life test was conducted.

[0035]

[Example 12] After mixing 6 g of silica with a zeta potential of +5 mV at pH = 5.0 to 1 kg of the above toner, the mixture was mixed with a 10 liter Henschel mixer at a rotation speed of 3000.
It was deposited under the conditions of stirring at rpm for 2 minutes. A developer was prepared by combining this toner with a silicon-coated ferrite carrier having a carrier current value of 0.5 μA, and a life test was conducted.

The results are shown in Table 1, Table 3, Table 5 (Examples 1 to 6), Table 2, Table 4, and Table 6 (Examples 7 to 12).

Further, as a comparative example, comparative samples were prepared corresponding to each of the above examples. Life tests were conducted on N/N, L/L, and H/H.

[0038]

[Comparative Example 1] After mixing 3 g of silica having a zeta potential of -15 mV at pH = 5.0 with 1 kg of the above toner, it was mixed with
The deposition was carried out under conditions of stirring at 00 rpm for 2 minutes. A developer was prepared by combining this toner with a silicon-coated ferrite carrier having a carrier current value of 0.5 μA, and a life test was conducted.

[0039]

[Comparative Example 2] After mixing 3 g of silica with a zeta potential of +15 mV at pH = 5.0 to 1 kg of the above toner, it was mixed with
The deposition was carried out under conditions of stirring at 00 rpm for 2 minutes. A developer was prepared by combining this toner with a silicon-coated ferrite carrier having a carrier current value of 0.3 μA, and a life test was conducted.

[0040]

[Comparative Example 3] After mixing 10 g of silica having a zeta potential of -5 mV at pH=5.0 with 1 kg of the above toner, the mixture was mixed with 10 g of silica having a zeta potential of -5 mV at pH = 5.0, and then mixed with
The deposition was carried out under conditions of stirring at 00 rpm for 2 minutes. A developer was prepared by combining this toner with a silicon-coated ferrite carrier having a carrier current value of 0.5 μA, and a life test was conducted.

[0041]

[Comparative Example 4] After mixing 10 g of silica having a zeta potential of +5 mV at pH = 5.0 with 1 kg of the above toner, the mixture was mixed with
The deposition was carried out under conditions of stirring at 00 rpm for 2 minutes. A developer was prepared by combining this toner with a silicon-coated ferrite carrier having a carrier current value of 0.5 μA, and a life test was conducted.

N/N, L/L, H/ of Comparative Examples 1 to 4 above
The life test results under the conditions of H are shown in Tables 7 and 8, respectively.
Shown in Table 9. The products according to these comparative examples showed an increase in the amount of charge, a decrease in ID, and a marked drop in gradation in a 50,000 copy test, but the products according to the examples of the present invention had excellent characteristics in all respects. there were. In the table, INI indicates the initial state, and K indicates 1000 copies.

[0043]

[Table 1]

[0044]

[Table 2]

[0045]

[Table 3]

[0046]

[Table 4]

[0047]

[Table 5]

[0048]

[Table 6]

[0049]

[Table 7]

[0050]

[Table 8]

[0051]

[Table 9]

[0052]

Effects of the Invention According to the present invention, by controlling the zeta potential of the fluidity improver, which has not been done in the past, the amount of triboelectric charge does not change much under conditions ranging from low temperature and low humidity to high temperature and high humidity, resulting in a clear This has the effect that high image density and good gradation can be obtained.

Claims (1)

[Claims] Claim 1: A fluidity improver having a zeta potential of -10 to +10 mV at a hydrogen ion concentration of pH 5 is attached to the surface of toner particles in an amount of 0.1 to 0.6% by weight based on the particles. Characteristic toner for developing electrostatic images