JP2002099117A - Electrostatic charge developer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic charge developer which satisfactorily retains solid state properties of a carrier giving high image quality and high resolution and maintains a long life. SOLUTION: In the two-component developer comprising a carrier obtained by coating the surface of an iron-base powder as a core material with silicon and a toner, the relation of an electric current [Ib] (μA) in the carrier to an electric current [Ia] (μA) in the core material at 200 V applied voltage is represented by 0.18<=[Ib]/[Ia]<=0.5, the electric current [Ib] (μA) in the carrier is in the range of 10-50 μA and the average particle diameter of the carrier is in the range of 50-100 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic charge developer used in copying machines, printers and the like,
In particular, the present invention relates to a two-component developer including a carrier and a toner, each of which has an iron-based powder as a core material and whose surface is coated with silicon.

[0002]

2. Description of the Related Art Conventionally, a two-component developer has been used in a digital image forming apparatus. The image forming apparatus comprises, for example, a carrier coated with a silicone resin, at least a binder resin and a colorant. In some cases, a developer composed of other additives is used.
A fixing device such as a copying machine using such a two-component developer is provided with an upper heat roller and a lower roller, and the upper heat roller is made of a silicon-coated aluminum tube, and the aluminum tube has a built-in heater lamp. Have been. The lower roller has an outer layer made of silicon rubber and a core material made of iron, and the toner on the paper passed by heat and pressure is fused and fixed to the paper by these two rollers.

The resin used for the toner is mainly an acrylic styrene resin, the charge control agent is an alloy azo compound, the colorant is carbon black, and the WAX is PEW.
AX and PPWAX are used. These materials are mixed, kneaded by a twin-screw kneading extruder, crushed into flakes by a cooling roller, classified by a jet mill,
A raw toner is produced. Silica is added to the raw toner as a fluidizing agent, and magnetite is mixed as a resistance adjusting agent to produce a toner. This toner and the carrier whose core material is silicon-coated with iron powder are stirred and mixed, and used as a two-component developer.

Japanese Patent No. 2701962 proposes a two-component developer comprising a carrier in which the surface of a carrier core material is covered with a polymer coating layer, and a toner. This two-component developer has a carrier characteristic represented by [(resistance value of carrier core material) / (carrier resistance value)] in the range of 0.020 to 0.20, and the toner (a) has a conductivity of (a). 3.0 × 10 ⁻¹⁰ s / cm or more, (b) 1.5% or less in terms of the number ratio of particles having a particle size of 16 μm or more, and (c) compression degree of 40% or less. The use of such a two-component developer prevents the carrier jump (carrier up) phenomenon in which the carrier together with the toner adheres to the surface of the electrostatic latent image, and the white spot caused by the carrier jump causes a problem in actual use. It is said that it will be suppressed to an extent that it will not be. When the carrier characteristic is 0.02 or more, carrier skipping is prevented and image whitening hardly occurs, whereas [(resistance value of carrier core material) / (carrier resistance value)] is 0.02. In the example below, it is said that many carrier jumps occur and the initial image density also becomes low.
Further, even when the carrier characteristics are 0.02 or more, when the toner conductivity is as low as 8.5 × 10 ⁻¹⁰ s / cm, carrier skipping cannot be prevented and image white spots often occur. . It is stated that if the carrier characteristics and the toner characteristics satisfy the above ranges, there is almost no white spotting and the initial image density shows a good value.

[0005] However, in the conventional two-component developer, [(resistance value of carrier core material) / (carrier resistance value)] is 0.02 for the carrier that determines the life.
Since it is limited to only 0 to 0.20, there is still room for improvement in providing high image quality, high resolution, and sufficient life for the carrier. That is, as [(resistance value of carrier core material) / (carrier resistance value)] increases,
Although the image density increases, a satisfactory image density cannot be obtained yet, and the phenomenon becomes more remarkable as a high-resolution image is formed. On the other hand, as [(resistance value of carrier core material) / (carrier resistance value)] becomes smaller, the image density further decreases, the amount of silicon coat coated on the carrier core material decreases, and the coating peels off after long life aging.
The amount of spent increases. Under these circumstances, high image quality is required to maintain the carrier physical properties of the developer design.
There is a demand for the development of an electrostatic charge developer having high resolution and long life.

Therefore, in recent years, the carrier has been reduced in particle size in order to achieve high image quality, high resolution, and long life. In order to maintain the long life of the developer and maintain high image quality, the silicon film of the carrier must be thickened.If it is thickened, it becomes a high resistance and low current carrier, and the image density is low. There are many problems that the concentration is particularly low. Further, when the silicon film is thin, the carrier is deteriorated by the stress of the developer, which is not suitable for a long life, and high image quality cannot be maintained.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in order to meet the above-mentioned problems and demands of the prior art, and has a high image quality, a high resolution and sufficient carrier physical properties, and a long life. It is an object to provide an electrostatic charge developer that is maintained.

[0008]

Means for Solving the Problems The present inventors have made intensive studies in view of the above-mentioned problems and demands of the prior art, and as a result, have found that a carrier having iron powder or the like as a core material and having a surface coated with silicon is provided. In a two-component developer for digital images using a two-component developer composed of a toner and a toner, in order to increase the carrier current, the amount of the silicon film is usually reduced, and the image density is secured as the performance. While the life property is inferior, in order to reduce the current value of the carrier, the amount of the silicon film is usually increased to ensure long life as the performance, but the image density is lowered and the image quality is impaired. Based on these relationships, high image quality, high resolution,
In order to ensure long life, the current value of the carrier core material is increased, the amount of silicon coating is increased, and the carrier current is also increased in total, resulting in high image quality, high resolution,
It has been found that long life can be improved. That is, the current value [Ib] of the carrier at a predetermined applied voltage is set in a predetermined range, and the relationship between the current value [Ia] μA of the carrier core material and the current value [Ib] μA of the carrier ([I
When b] / [Ia]) is selected to satisfy a limited range, the resistance can be suppressed even if the film thickness is large, and satisfactory image density, high image quality and high resolution can be obtained, and carrier Have been found to achieve extremely high long life, and have led to the present invention.

Accordingly, the present invention has the following configuration to achieve the above object. (1) The electrostatic charge developer according to the present invention is a two-component developer having a core of iron-based powder and having a surface coated with silicon and a toner.
The relationship between the current value [Ia] μA of the core material and the current value [Ib] μA of the carrier is 0.18 ≦ [I
b] / [Ia] ≦ 0.50, the carrier current value [Ib] μA is in the range of 10 μA to 50 μA, and the carrier average particle size is in the range of 50 to 100 μm.

(2) In the electrostatic charge developer described in (1), the carbon content (Csi)% of silicon is 0.15 (%).
≤ Csi ≤ 0.30 (%). (3) In the electrostatic charge developer according to (1) or (2), the toner has a dielectric loss value (tan δ) and a resistance value (R) of 2.0 × 10 ⁻³ ≦ tan δ ≦ 3.5 ×. It is characterized by being within the range of 10 ⁻³ and 200 × 10 ⁹ (Ω) ≦ R ≦ 290 × 10 ⁹ (Ω). (4) In the electrostatic charge developer according to any one of (1) to (3), a deviation value (σ) and a center value (Mean) in a charge amount distribution of a start developer in which the carrier and the toner are mixed. , And the reverse charge amount ratio (Qn: [positive charge amount number] ×
100 / [number of negative charges + number of positive charges]) is 0.8
≦ σ ≦ 2.0, −2.0 ≦ Mean ≦ −0.7, and Qn ≦
It is characterized in that it is in the range of 15.0 and shows one peak in the output charge amount distribution diagram. Here, the start developer means an unused developer used when setting up the machine.

(5) A digital image forming method using the electrostatic charge developer according to any one of (1) to (4),
The toner has a resolution of 600 dpi or more, and the volume average particle diameter of the toner is in the range of 6.0 to 10.0 μm. The developing method is a counter method, the drum diameter is 35φ or less, and the process speed is 61 mm /. sec ~ 122m
The process speed is selected within the range of m / sec, and the resolution is changed to output the process speed. (6) A digital image forming apparatus using the electrostatic charge developer according to any one of (1) to (4), wherein the resolution is 600 dpi or more, and the volume average particle diameter of the toner is 6.0.
The developing method is a counter method, the drum diameter is 35φ or less, and the process speed is 6 μm.
It is selected within the range of 1 mm / sec to 122 mm / sec.

[0012]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a characteristic diagram showing the charge amount distribution of the developer when the deviation (σ) is 0.6 and 3. FIG. 2 is a characteristic diagram showing the charge amount distribution of the developer when the deviation (σ) of the present embodiment is 1.5. FIG. 3 is a characteristic diagram showing the charge amount distribution of the developer when the center value (Mean) is -2.3 and -0.3. FIG.
FIG. 6 is a characteristic diagram illustrating a charge amount distribution of a developer when a central value (Mean) of the present embodiment is −1.2. FIG. 5 is a characteristic diagram showing the charge amount distribution of the developer when the reverse charge amount ratio (Qn) is 17%. FIG. 6 shows the reverse charge amount ratio (Q
FIG. 9 is a characteristic diagram showing a charge amount distribution of the developer when n) is 8%. FIG. 7 is a characteristic diagram showing a charge amount distribution of the developer having two peaks. FIG. 8 is a characteristic line diagram showing the charge amount distribution of the developer showing one peak (peak) in this embodiment.

The electrostatic charge developer of the present invention is a two-component developer having an iron-based powder as a core material and comprising a carrier coated with silicon and a toner. The core material is not limited to reduced iron, iron oxide, ferrite, iron-aluminum alloy,
Further, it is an iron-based powder in which current characteristics are adjusted by appropriately oxidizing other alloys or the like in an oxidation furnace or the like. In particular, the iron-based powder is desirably an iron powder whose surface is made of an ordinary inexpensive reduced iron and / or iron oxide and oxidized. The surface of the core material of the carrier is desirably oxidized in an oxidation furnace so that the current value can be selected within a predetermined range described later when the core material is subjected to the silicon film treatment.

In the electrostatic developer of the present invention, an applied voltage of 20
The relation between the current value [Ia] μA of the core material at 0 V and the current value [Ib] μA of the carrier is 0.18 ≦
[Ib] / [Ia] ≦ 0.50, especially 0.25 ≦ [Ib]
/[Ia]≦0.35 is preferred. If the current relation ratio [Ib] / [Ia] exceeds the above range, the amount of silicon film is small, so that long-life spent increases and the coating peels off. On the other hand, the current relation ratio [Ib] /
When [Ia] is below the above range, the silicon coating amount is increased and the long life of the carrier is improved. However, since the carrier becomes a high resistance carrier, the line width of one line is 7 as an edge effect.
5 μm or less, reproducibility of one dot diameter becomes 60 μm or more,
Image density tends to decrease.

Not only the current relation ratio in the carrier but also the current value [Ib] of the carrier is 10 μA to 10 μA.
It is preferably in the range of 50 μA, especially in the range of 15 μA to 30 μA. When the current value [Ib] falls below the above range,
If the image density is low and exceeds the above range, the carrier resistance is too low and high image quality such as fine lines cannot be obtained. The average particle size of the carrier is in the range of 50 to 100 μm, particularly preferably in the range of 58 to 75 μm. If the average particle size of the carrier exceeds the above range, the charge amount of the developer becomes low, the fine lines are hardly reproduced, and a high quality image cannot be obtained sufficiently. Conversely, if the average particle size of the carrier is less than the above range, the charge amount increases, and the image density may decrease.

Examples of the silicon resin of the silicon film include methyl silicon, dimethyl silicon, and acrylic silicone resins, and a silane coupling agent such as an aminosilane coupling agent is added as an additive or an auxiliary agent. And need not be limited to these. In the electrostatic developer of the present invention, the silicon has a carbon content (Csi)% of 0.15 (%) ≦ C
It is preferably in the range of si ≦ 0.30 (%), and particularly preferably in the range of 0.15 (%) ≦ Csi ≦ 0.25 (%).

Even if the relationship between the carrier current value of the core material and the carrier current value, the current value of the carrier, and the carrier particle size are specified, the shape is irregular because the core material is iron powder. It is difficult to coat the carrier uniformly with a silicon film. In order to confirm that silicon is uniformly coated on the carrier, it is desirable to measure the amount of carbon of silicon coated on the carrier. When the relation ratio of the current value in the carrier is small, the amount of the silicon film increases, but it is necessary to check whether the carrier is indefinitely formed with respect to the amount of silicon input during the production and whether the carrier is uniformly attached. For example, even if the apparent current value and the relationship ratio of the carrier are within the specified range, the silicon coating state of the uneven portion on the carrier surface is different, and it is ideal that the unevenness is uniformly coated. At the present time, it is easy to be coated on the portion and hardly coated on the concave portion. The carrier current is easy to dynamically measure the current between the carrier surfaces, but the carbon amount of silicon can be measured by firing the carrier at high temperature and measuring the carbon amount in the silicon resin. Can be measured. In short, the carrier surface convexity is effective to obtain high image quality and high resolution at the beginning, and the convexity of the carrier surface is easily contaminated and peeled off gradually with long life, and the effect of the silicon film of the concave part is obtained according to the life. It is desirable to define the amount of carbon in silicon within the above requirements.

In the electrostatic charge developer of the present invention, the toner comprises:
At least a binder resin, and a colorant, a charge control agent,
A resistance adjusting agent, a release agent, a fluidizing agent and the like are added. As the binder, styrene, α-methylstyrene, halogenated styrene, styrenesulfonic acid, sulfonamidestyrene, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, acrylic styrene copolymer And the like, but not limited thereto. The binder resin is used not only in one kind but also in a combination of two or more kinds. Examples of the charge control agent include a base dye, a metal complex salt dye, and a fatty acid soap. Specific examples include a metal-containing azo compound and a bischromate, but are not limited thereto. As the colorant, black pigments such as carbon black, acetylene black, and aniline black can be preferably mentioned. Examples of the wax as the release agent include, but are not limited to, polypropylene, polyethylene, and carnauba wax. Examples of the resistance adjuster include magnetite and titanium oxide. Examples of the fluidizing agent include those commonly used such as silica.

The toner in the electrostatic charge developer of the present invention comprises:
The dielectric loss value (tan δ) and the resistance value (R) are 2.0
× 10 ⁻³ ≦ tanδ ≦ 3.5 × 10 ⁻³ and 200 × 10
⁹ (Ω) ≦ R ≦ 290 × 10 ⁹ (Ω). Even if the relation ratio of the current value in the carrier, the current value of the carrier, the average particle size of the carrier, and the amount of carbon in silicon are selected, in order to further ensure high image quality and high resolution, it is necessary to use a dielectric material of the toner. It is desirable to limit the loss value and the resistance value. Even if the same material is used in manufacturing the toner, the dielectric loss value and the resistance value of the toner change under kneading conditions and cooling conditions in the manufacturing process. This is because the dispersion condition of each material changes. To produce the developer, the toner / carrier is used by uniformly mixing in a range of 5% to 11% by weight, but outside the above range of the toner, 2.0 × 10 ⁻³ > tan
When δ, R> 290 × 10 ⁹ , the toner resistance is too high,
In addition, the charge amount increases, and the image density tends to decrease. On the other hand, tan
When δ <3.5 × 10 ⁻³ , 200 × 10 ⁹ > R, the resistance of the toner is too low, the charge amount becomes low, and the BG tends to rise easily.

The electrostatic charge developer of the present invention has a deviation value (σ), a center value (Mean), and a reverse charge amount ratio (Qn: [n]) in the charge amount distribution of the start developer in which the carrier and the toner are mixed. Positive charge quantity] x 100 / [negative charge quantity +
Positive charge number]) is 0.8 ≦ σ ≦ 2.0, −2.0 ≦ Me
It is desirable that they are in the ranges of an ≦ −0.7 and Qn ≦ 15.0, and show one peak (one peak) in the output charge amount distribution diagram. Here, the start developer refers to a state of an unused developer used when setting up the machine.

If the condition is not satisfied, the deviation (σ) in the charge amount distribution is difficult to adjust if it is less than 0.8. If it is extremely small, the friction between the drum and the cleaning blade increases. Torque may be abnormal. Conversely, if the deviation value (σ) exceeds the above range, the transfer efficiency becomes worse and the toner consumption increases (see FIGS. 1 and 2). Next, when the central value (Mean) exceeds -2.0, the phenomenon that the image density is inferior occurs due to an increase in charge due to a large number of charge amounts. On the other hand, when the central value (Mean) exceeds -0.7, the charge amount is low, and BG rise (background value rise) and the like occur (see FIGS. 3 and 4).

Next, when the reverse charge amount ratio exceeds 15.0%, PC fogging (toner adhesion phenomenon on a non-image portion of the drum) easily occurs on the drum, and the amount of discharged toner increases.
A problem occurs in which the toner consumption becomes severe (see FIGS. 5 and 6). Finally, in the charge amount distribution diagram, when a developer was prepared in which 65 μA and toner were uniformly mixed as a core material carrier to be used, the charge amount distribution had two peaks, and 6 parts of silicon were coated on this. As a result, the two peaks held by the core material overcome the chargeability of the resin by the silicon film, and the carrier comes to show one peak (see FIGS. 7 and 8 described later). When the charge amount distribution diagram of the carrier has a plurality of peaks, the charge amount σ value is large, the transfer efficiency is poor, and BG and PC fogging tend to occur.

In the image forming method of the present invention, the above-mentioned electrostatic charge developer is used, and the resolution is 600 dpi or more and the volume average particle diameter of the toner is in the range of 6.0 to 10.0 μm. Using a counter method as the developing method, the drum diameter is 35φ or less, and the process speed is selected within the range of 61 mm / sec to 122 mm / sec, and the resolution is changed to output the process speed. is there.

Even if development is performed at two or more process speeds in which the resolution is changed by the copy and printer functions and the output is performed, these developers can sufficiently withstand the stress. Even if the electrostatic charge developer satisfies the conditions as a developer, it is desirable to control the development conditions and process conditions of the output device in order to optimize high image quality, high resolution, and long life. . In particular, since the above-mentioned developer works effectively against deterioration and fatigue of the carrier over a long life, it can be sufficiently adapted to such a developing method. Further, the image forming apparatus of the present invention is one to which the above-described image forming method is applied, and the selectivity as the apparatus is sufficiently widened.

[0025]

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. Prior to the description of the implementation of the electrostatic charge developer according to the present invention, various measurement methods to be performed, that is, a carrier current measurement method, a carrier particle size measurement method, a toner particle size measurement method, and a line width are described. The following (a), (b), (c), and (d) are used for a dot diameter measurement analyzer, an image density measurement device, a carbon amount measurement device, a dielectric loss measurement device, and a charge distribution measurement device.
This will be described in detail in (e), (f), (g), (h), and (i).

(A) Carrier current measurement About 1,000 g of a carrier sample was collected, and the room temperature was 20 to
Exposure to the environment at 26 ° C. and a humidity of 50 to 60% RH for 15 minutes or more. The height of the spikes in the developing tank with the built-in magnet roll is controlled (the height from the magnet roll surface to the top of the developer when the developer is rotated by the magnet roll and comes out on the surface in contact with the photosensitive drum). A counter electrode is provided at a fixed distance in opposition to the conductive sleeve provided with the doctor blade (spike height control plate). During this time, the carrier is magnetically attracted, and the magnet roll in the sleeve is rotated to set a gap between the counter electrodes. 200V DC voltage applied to
Detect by current value with a resistor in between. The unit of the current value is
(ΜA). (B) Carrier particle size measurement About 100 g of a sample was weighed to the order of 0.1 g, and the sieve was 14 g.
Using a 9 μm to 44 μm sieve, 149, 105,
The trays are stacked in the order of 74, 63, and 44 μm and a tray is placed on the bottom. This is rotated by a vibrator at a horizontal rotation speed of 285.
Shake at 150 rpm for 15 minutes at 150 rpm. After sieving,
Weigh each pan. Calculated by weight percentage, JIS-H
2601.

(C) Measurement of Particle Size of Toner A particle size distribution is measured with a Coulter Multisizer measuring device. Take the volume average particle size D50 value. (D) Measurement of line width and dot diameter Measurement of line width and dot diameter using microscope image data. Measurement analysis in the process of image input, calibration, processing range setting, extraction, measurement, and data display. I do. As an example, as a device for image input and calibration, a digital Hi-Vision microscope BS-
Using a 7800 (CSK Corporation) 200 × lens, an image sample is taken into data and calibration is performed. Next, this data was analyzed using the analysis software WinR.
A processing range is set with OOF (MITANNI, CORPATION), extracted, the area of a target line or dot is determined, and the distance between each vertical direction and horizontal direction is calculated by denominator.

(E) Image density measurement Macbeth densitometer manufactured by Macbeth Co., Ltd. (f) Measurement of charge amount Approximately 0.2 g of a developer in which a carrier and a toner are mixed is weighed and weighed (weighing g: α), and immediately a blow-off machine ( Toshiba Chemical TB-200). Assuming that the blow-off pressure is 1.0 kg / cm ² , the blow-off value after 30 seconds is A, and the toner concentration of the developer at this time is B%,
It is calculated from the following equation. Charge amount μC / g = A × 100 / (B × α) (g) Carbon amount measuring machine HORIBA, Ltd. Carbon ion analyzer in metal (model EMIA-
1200). As a component contained in the silicon resin coated on the carrier, a carbon component such as a methyl group or a methoxy group is detected by the amount of CO ₂ gas when fired in a firing furnace in the analyzer. Before this measurement, as a blank test, the carbon material of impurities contained in the core material alone was removed by a measuring machine using a core material alone as a blank test, and the silicon coating of the measurement carrier was determined from the calibration curve of the carrier whose known silicon carbon amount was known. The amount of carbon is detected. The unit of measurement is expressed in%.

(H) Dielectric loss measuring device Dielectric loss measuring device (TR-10C) manufactured by Ando Electric Co., Ltd.
Type), oscillator (WBG-9 type), equilibrium point detector (BDA
-9), constant temperature bath (TO-19), electrode for solid (SE)
(-70 type). As a measurement principle, there is a bridge method as a basic method for measuring a dielectric constant. This is a method of comparing the capacitance Cx when the flat capacitor is filled with the dielectric and the capacitance Co when empty. At this time, the dielectric constant is obtained by f = Cx / co. Co = electrode area / (11.3 × sample thickness), tan δ
= 1 / (ωCx · ΔR), ω = 2πf, ΔR = R′-Ro 1 g of toner is set in a tablet molding machine, tablets are produced by the molding machine, the frequency of the oscillator is set to 1 kHz, and the solid electrode is A tablet is placed in the center, and a guard electrode is placed on the tablet, and the measurement is performed. (CONDUCTANCE) is adjusted as a zero equilibrium operation. The value at this time is defined as Ro. Next, apply voltage and
5 minutes later, (CONDUCTANCE) and (CAPACI)
TANCE). These values are R ′ and Cx. After the measurement is completed, the thickness of the tablet is measured at one point at the center and at four points around the center, and this is defined as tx. Calculation formula tanδ = Gx / ωCx ε ′ = Cx / co = 1.13 · txcCx / A R = 10A / (Gx · tx) where Gx = RATIO × (R′−Ro) ω = 2πf (f = 1 kHz) A is the effective electrode area ‥ 0.952π ≒ 2.83 (cm ² )

(I) Charge amount distribution measuring device A particle charge distribution measuring device manufactured by Hosokawa Micron (E-SPART Analyzer model E)
ST-1) Method: Moving speed of particles in a sonic vibration field in a DC electric field Simultaneous measurement of particle diameter and charge amount based on measurement by laser Doppler method Measurement unit 1) Laser light source: 12 mW He-Ne laser (wavelength 632.8 nm) 2) Sound wave transmitter: frequency 1 kHz 3) High voltage generator: 5000 V max. 4) Flow control system: Flow meter 1000 CC / min pump max. 5) Operation circuit: RS232C, 4800/1200 port rate switching Measurement feeder Start developer is set on the table, and magnet voltage is applied to rotate the table.
_The toner jumps with _two gases and is sucked into the measurement. As setting conditions, pulse duration .... 3-5, interval .... 4
~ 6sec, rotation speed ・ ・ ・ 150 ~ 250 / 1500rp
m, N ₂ gas: 0.3 to 0.4 kg / cm ₂ G, up to 3000 counts. This is calculated and counted for negative and positive polarities for each d (μm) particle size of each channel, totaled, and the difference, central value, and reverse charge amount are calculated. In the output diagram, Q / d is plotted on the horizontal axis, and the number of N (au) is plotted on the vertical axis.

Next, Examples and Comparative Examples of the electrostatic charge developer according to the present invention will be described. However, the present invention is not limited by the materials used in the embodiments described below. By way of example, some examples will be dealt with in order to determine what is appropriate. First, a carrier having an iron-based powder as a core material and having a surface coated with silicon has an arbitrary carrier current value and particle size,
The toner is pre-mixed with acrylic styrene as the main resin, an alloy azo compound as a charge control agent, and carbon black as a colorant and polyethylene WAX as a WAX according to the toner component mixing ratio with a mixer, and kneaded with a twin-screw extruder. After cooling with a cooling roller, the mixture was crushed into flakes by a crusher and then classified by a jet mill to obtain a raw toner having a volume average particle size of 7.5 μm. To this, silica as a fluidizing agent and magnetite as a resistance adjusting agent could be externally added by a mixer. The toner and the carrier were stirred and mixed at 7.5% by weight, and stirred until a predetermined charge amount was secured to obtain a developer. As Examples and Comparative Examples,
Table 1 shows the manufacturing conditions (components) to be changed.

[0032]

[Table 1]

(Example 1) An iron powder having an average particle diameter of 60 µm was flowed into an oxidizing furnace under high-temperature conditions, and the surface of the carrier core material was oxidized to a current value of 95 µA, which was coated with silicon ( The amount of silicon was 9 parts), the coating was dried and cured to adjust the carrier current value to 19 μA. The relationship ratio in the carrier was 0.20. At this time, the amount of carbon (Csi) in silicon is 0.2.
5 (Example 2) Iron powder having an average particle diameter of 60 µm was flowed into an oxidizing furnace under high-temperature conditions to oxidize the surface of the carrier core material to adjust the current value to 95 µA, and then coated with silicon (amount of silicon: 6 parts), dried and cured to prepare a film having a carrier current value of 29 μA. The relationship ratio in the carrier was 0.31. At this time, the amount of carbon (Csi) in silicon is 0.17.

(Comparative Example 1) An iron powder having an average particle diameter of 60 µm was flowed into an oxidizing furnace under high-temperature conditions to oxidize the surface of the carrier core material to adjust the current value to 35 µA. The surface of the core material (amount of silicon: 3 parts), the coating is dried and cured, and the carrier current value is 23μ.
It was created by adjusting A's. The relationship ratio in the carrier was 0.66. (Comparative Example 2) Iron powder having an average particle diameter of 60 µm was flowed into a high-temperature oxidation furnace to oxidize the surface of the carrier core material to adjust the current value to 35 µA, and this was coated with silicon (silicon amount: 9). ), And the coating was dried and cured to prepare a coating having a carrier current value of 6 μA. The relationship ratio in the carrier was 0.17. (Comparative Example 3) An iron powder having an average particle diameter of 60 µm was flowed into an oxidizing furnace with slightly lowered high-temperature conditions, the surface of the carrier core material was oxidized, and the current value was adjusted to 65 µA, and this was coated with silicon. (Silicon amount: 3 parts), and the coating was dried and cured to adjust the carrier current value to 40 μA. The relationship ratio in the carrier was 0.62.

(Comparative Example 4) An iron powder having an average particle diameter of 60 µm was flowed into an oxidizing furnace under a high temperature condition to oxidize the surface of the carrier core material to adjust the current value to 65 µA, and this was coated with silicon ( The amount of silicon was 9 parts), the film was dried and cured to adjust the carrier current value to 10.5 μA. The relationship ratio in the carrier was 0.16. (Comparative Example 5) An iron powder having an average particle diameter of 60 µm was further passed through an oxidizing furnace with the high temperature condition lowered, the surface of the carrier core material was oxidized to adjust the current value to 95 µA, and this was coated with silicon. (Amount of silicon: 3 parts) The coating was dried and cured to adjust the carrier current value to 51 μA to prepare a film. The relationship ratio in the carrier was 0.54.

(Example 3) Air was passed through an iron furnace having an average particle diameter of 60 µm into an oxidizing furnace under a high temperature condition, and the surface of the carrier core material was oxidized to adjust the current value to 65 µA, and this was coated with silicon ( The amount of silicon was 6 parts), and the film was dried and cured to adjust the carrier current value to 23 μA. The relationship ratio in the carrier was 0.35. At this time, the amount of carbon (Csi) in silicon is 0.1.
7 (Example 4) Iron powder having an average particle diameter of 60 µm was flowed into an oxidizing furnace under high-temperature conditions to oxidize the surface of the carrier core material to adjust the current value to 95 µA, and then coated with silicon (amount of silicon: 10 parts), dried and cured to prepare a film having a carrier current value of 19 μA. The relationship ratio in the carrier was 0.20. At this time, the carbon amount (Csi) in the silicon is 0.31.

(Example 5) An iron powder having an average particle diameter of 60 µm was flowed into an oxidizing furnace under a high temperature condition to oxidize the surface of the carrier core material to adjust the current value to 65 µA, and this was coated with silicon ( The amount of silicon was 4 parts), the film was dried and cured to adjust the carrier current value to 23 μA. The relationship ratio in the carrier was 0.35. At this time, the amount of carbon (Csi) in silicon is 0.1.
4. (Example 6) Air was passed through an oxidizing furnace under high temperature conditions for iron powder having an average particle diameter of 60 µm, and the surface of the carrier core material was oxidized to adjust the current value to 95 µA, and this was coated with silicon (silicon amount: 9 parts), dried and cured to prepare a film having a carrier current value of 19 μA. The relationship ratio in the carrier was 0.31. At this time, the amount of carbon (Csi) in silicon is 0.17. The toner in the developer has a cylinder temperature of 8 as a kneading condition.
At 0 ° C., 200 rpm, tan δ = 2.9 × 10 ⁻³ , R = 238 × 1 of the toner added, cooled, crushed, classified, and externally added.
It was ⁹ Ω.

(Example 7) Iron powder having an average particle diameter of 60 µm was flowed into an oxidizing furnace under high temperature conditions to oxidize the surface of the carrier core material to adjust the current value to 95 µA, and this was coated with silicon ( The amount of silicon was 9 parts), the coating was dried and cured to adjust the carrier current value to 19 μA. The relationship ratio in the carrier was 0.31. At this time, the amount of carbon (Csi) in silicon is 0.1.
7 The toner in the developer was kneaded at a cylinder temperature of 70 ° C. and 200 rpm, and cooled, crushed, classified, and tan δ = 1.9 × 10 ^{-3 of} the externally added toner.
R = 300 × 10 ⁹ Ω.

(Embodiment 8) Iron powder having an average particle diameter of 60 μm was flowed into an oxidizing furnace under a high temperature condition to oxidize the surface of the carrier core material to adjust the current value to 95 μA, and this was coated with silicon ( The amount of silicon was 9 parts), the coating was dried and cured to adjust the carrier current value to 19 μA. The relationship ratio in the carrier was 0.31. At this time, the amount of carbon (Csi) in silicon is 0.1.
7 The toner in the developer was kneaded at a cylinder temperature of 100 ° C. and 200 rpm, and cooled, crushed, classified and tan δ of the externally added toner = 4.0 × 10 ⁻³ ,
R = 190 × 10 ⁹ Ω.

(Example 9) An iron powder having an average particle diameter of 60 µm was flowed into an oxidizing furnace under high-temperature conditions to oxidize the surface of the carrier core material to adjust the current value to 95 µA, and this was coated with silicon ( The amount of silicon was 9 parts), and the film was dried and cured to adjust the carrier current value to 19 μm. The relationship ratio in the carrier was 0.31. At this time, the amount of carbon (Csi) in silicon is 0.1.
7 As for the toner in the developer, the kneading conditions are as follows.
Classification, tan δ of externally added toner = 1.9 × 10 ⁻³ , R =
It was 300 × 10 ⁹ Ω. Using the carrier and the toner, the toner weight ratio in the developer is adjusted to 7.5%, and the mixture is uniformly mixed with a Nauta mixer. Set time is 30
When the charge amount distribution of the developer when mixed for
= 1.0, Mean = -0.9, reverse charge amount is 8%, and the charge amount distribution diagram shows one peak (peak).

Example 10 Air was passed through an iron furnace having an average particle diameter of 60 μm through an oxidizing furnace at a high temperature to oxidize the surface of the carrier core material to adjust the current value to 95 μA, which was coated with silicon ( The amount of silicon was 9 parts), the film was dried and cured to adjust the carrier current value to 19 μA. The relationship ratio in the carrier was 0.31.
At this time, the amount of carbon (Csi) in the silicon is 0.1.
Seventeen. The toner in the developer was kneaded at a cylinder temperature of 80 ° C. and 200 rpm, and cooled, crushed, classified, and tan δ of the externally added toner = 1.9 × 10 ⁻³ ,
R = 300 × 10 ⁹ Ω. Using the carrier and the toner, the toner weight ratio in the developer is adjusted to 7.5%, and the mixture is uniformly mixed with a Nauta mixer. When the charge amount distribution of the developer when mixed for 15 minutes as the set time was measured, σ = 1.5, Mean = −0.3, the reverse charge amount was 20%,
The charge amount distribution diagram shows two peaks.

(Example 11) An iron powder having an average particle diameter of 60 µm was flowed into an oxidizing furnace under a high temperature condition to oxidize the surface of the carrier core material to adjust the current to 95 µA, and then coated with silicon (silicon). Amount: 9 parts), dried and cured to adjust the carrier current value to 19 μA. The relationship ratio in the carrier was 0.31. At this time, the amount of carbon (Csi) in silicon is 0.1.
7 The toner in the developer was kneaded at a cylinder temperature of 80 ° C. and 200 rpm, and cooled, crushed, classified, and tan δ of the externally added toner = 1.9 × 10 ⁻³ ,
R = 300 × 10 ⁹ Ω. Using the carrier and the toner, the toner weight ratio in the developer is adjusted to 7.5%, and the mixture is uniformly mixed with a Nauta mixer. When the charge amount distribution of the developer after mixing for 60 minutes as the set time was measured, σ = 0.9, Mean = −2.5, the reverse charge amount was 3%, and the charge amount distribution diagram shows one peak. Indicated.

Using the various developers described above, the image density, image quality, and other physical properties were confirmed in a printer mode using a SHARP digital copier AR machine (600 dpi) with a process speed set to 122 mm / sec. . Table 2 shows the results. The evaluation criteria in Table 2 are as follows. (A) High quality solid image density ○: 1.35 or more, Δ: 1.28 to 1.30 μm, ×:
1.28 μm or less. (B) High image quality γ characteristics (gradation: photographic image is judged by daylight) ○: good, Δ: normal, × bad (c) High image quality fog (whiteness meter) ○: 0.8 or less , Δ: 0.8 to 1.2, ×: 1.2 or more (d) High image quality PC fog (Mafbes densitometer) ○: 0.1 or less, Δ: 0.1 to 0.12 ×: 1.2 (E) High resolution 1 line line width reproducibility ○: 83 μm or more Δ: 75 to 83 μm X: 75 μm or less (f) High resolution 1 dot diameter reproducibility ○: 60 μm or more, Δ: 50 to 60 μm, ×: 50 μm
(G) Long life High image quality (80,000 sheets copy performance) ○: Good, △: Normal ×: Poor (h) Long life High resolution function (80,000 sheets printer performance) ○: Good, △: Normal , ×: bad (i) Comprehensive evaluation 良好: extremely good, ○: good, Δ: normal, ×: bad

[0044]

[Table 2]

In Examples 1 and 2 and Comparative Examples 1 to 6,
When the relation ratio of the current value of the carrier to the current value of the core material changes. When the current relation ratio is 0.50 or more, the initial high image quality may be more satisfactory depending on the carrier current value, but the silicon amount is small. Insufficient long life, coat peeling and spent on the carrier surface increase, high image quality and high resolution are poor,
Fog, PC fog, increase in toner consumption, etc. occur.
On the other hand, when the current relation ratio is 0.18 or less, high resolution is obtained due to the edge effect, but image density is low. Current relation ratio is 0.3
At 1, there was almost no problem. That is, the applied voltage 20
The current value [Ia] of the carrier core material at 0 V is 60 to 1
The core material was coated with silicon to prepare a current value [Ib] of 10 to 50 μA, and the current value of the carrier and the current value of the core material were 0.1 μA.
If the relation ratio of 8 ≦ [Ib] / [Ia] ≦ 0.50 is satisfied,
Satisfactory image density, high image quality, and high resolution can be obtained, and a long-life developer can be obtained.

Those out of the above range, for example, the current value of the carrier core material in Comparative Example 1 was 35 μA,
And the carrier current value was 23 μA, and [Ib] /
If a carrier having [Ia] = 0.65 is used, it is good at the beginning, but as the number of copies increases, the carrier resistance decreases.
When it was 5 μm or less, BG increased and toner consumption increased. Therefore, the current value of the core material of the carrier in Comparative Example 2 was 35 μm.
A. When a carrier having 9 parts of silicon and a carrier current value of 6 μA and [Ib] / [Ia] = 0.17 was used, the image density was initially low, but the long life was good. Yes, as a result, they were incompatible. From the comparative tests of Comparative Examples 1 and 2, in order to increase the current value of the core material of the carrier, the degree of oxidation of the surface of the core material was reduced by oxidation treatment to obtain a low-resistance, high-current core material carrier, and a silicon film was formed. The amount was adjusted and considered. In Comparative Example 3, the current value of the carrier core material was 65 μA, the silicon was coated in three parts, the carrier current was 40 μA, and the carrier of [Ib] / [Ia] = 0.62 was used. Was satisfied,
The edge effect was small, the reproducibility of fine lines was poor, the line width of one line was 75 μm or less, and a high-quality image could not be obtained.

Next, the current value of the carrier core material in Comparative Example 4 was 65 μA, the carrier current was 10.5 μA by coating 9 parts of silicon, and the carrier of [Ib] / [Ia] = 0.16 was used. Then, the image quality was initially high with an edge effect, but the image density was low. Next, as a further study, the current value of the core material of the carrier in Comparative Example 5 was 95 μm.
A, when three parts of silicon are coated and the carrier current is 51 μA, and the carrier of [Ib] / [Ia] = 0.54 is used, the image density is initially satisfactory.
G is high, edge effect is small, and line width of one line is 75μ.
Below m, high quality images cannot be obtained. On the other hand, in the embodiment, the current value of the core material of the carrier in the second embodiment is 95 μA, the carrier current value is 29 μA by coating 6 parts of silicon, and [Ib] / [Ia] = 0.31. When a carrier is used, an edge effect is initially generated, and 1
The line width was 75 μm or less, high image quality, good image density, and long life. In Example 3, the current value of the core material of the carrier was 65 μA, 6 parts of silicon were coated, and the carrier current value was 23 μA. [Ib] / [Ia]
Using a carrier with = 0.34, initially,
It has an edge effect, a line width of one line of 75 μm or less, high image quality, good image density, and long life.

In Examples 2 to 5, when the amount of carbon in the silicon of the carrier changes, in Example 4, 10 parts of the amount of silicon was charged, and the current value [Ib] and the current relation ratio [Ib] /
[Ia] satisfied the conditions, but the porosity of the concave portions of the carrier (the void inside the carrier core material) remained uncured due to the accumulation of silicon, and there was no problem at first in the initial stage. Etc. tended to increase. In Example 5, four parts of silicon were charged, and the current value [Ib] and the current relationship ratio [Ib] / [Ia] satisfied the conditions. However, there was little silicon resin in the carrier concave portion, and there was no problem at first. However, the long life, the recession with less silicon made it easier to league, and this also showed a tendency for BG etc. to rise. In Examples 2 and 3, silicon was hardened with an appropriate amount of silicone resin in the carrier concave portion, and there was almost no problem.

In Examples 6 to 8, when the dielectric loss value and the resistance of the toner change, in Example 7, the toner resistance is high, and as the toner is replenished, the toner performance becomes dominant and the charge amount increases. And the image density was slightly inferior (high-quality solid density). In Example 8, the toner resistance was low, and as the toner was replenished, the toner performance became dominant, the charge amount tended to decrease, and the BG was slightly inferior (high-quality PC fog). In Example 6, the toner resistance was suitable, and the toner performance became dominant as the toner was replenished, and there was almost no problem. In Examples 9 to 11, when the charge amount distribution of the start developer was changed, in Example 10, the reverse charge amount% was 20%, and BG and PC fog increased due to toner supply during life. In the eleventh embodiment, Mean
Was -2.5, the image was slightly negatively charged due to strong negative charge as a whole, and toner replenishment during life. In Example 9, the charge amount distribution was suitable, and the developer was balanced without any problem even when the toner was supplied during life.

(Examples 12 and 13) In Example 12, the same developer as in Example 9 was used, the toner particle size at that time was 7.5 μm, and a digital image having two or more process speeds was used. This is applied to a forming apparatus. In Example 13, iron powder having an average particle size of 60 μm was flowed into an oxidizing furnace at a high temperature to oxidize the surface of the carrier core material to adjust the current value to 95 μA, and then coated with silicon (amount of silicon: 9 parts), dried and cured to prepare a film having a carrier current value of 19 μm. The relationship ratio in the carrier was 0.31. At this time, the amount of carbon (Csi) in silicon is 0.17. The toner in the developer has a cylinder temperature of 80 as a kneading condition.
° C, 200 rpm, tan δ = 1.9 × 10 ^-3 , R = 300 × 10 ⁹ for the toner which was cooled, crushed, classified and externally added.
Ω. Using the carrier and the toner, the toner weight ratio in the developer is adjusted to 7.5%, and the mixture is uniformly mixed with a Nauta mixer. After mixing, when the charge amount distribution of the developer was measured, σ = 1.9, Mean = −0.7, and the reverse charge amount was 14
%, The distribution diagram of the charge amount shows one peak (peak). In Example 13, the toner particle size at that time was set to 10.5 μm,
This is applied to a digital image forming apparatus having two or more types of process speeds.

High image quality, high resolution and long life durability at each process speed, and comprehensive evaluation were performed. The evaluation methods in Table 3 are based on the total evaluation of solid image quality, γ characteristics, and high image quality in fog.
×: Judgment is made in three stages of bad. Also, the total evaluation of the high resolution based on the lines and dots is determined in three stages of ：: good, Δ: normal, and ×: bad. The long life durability and overall evaluation were evaluated in four stages: ◎: extremely good, ：: good, Δ: normal, and ×: bad.

[0052]

[Table 3]

In Example 13, the toner particle diameter was 10.5 μm.
m, high image quality and high resolution are satisfactory when the process speed is 120 mm / sec, but the process speed is 61 mm / sec.
At / sec, some fog occurs as image quality. In addition, BG and PC fog slightly increased due to toner supply during long life. In Example 12, the toner particle size was 7.5 μm.
Therefore, the developer was stable, and the developer was very well-balanced even when the toner was supplied over a long life.
As a supplement to this, if the process speed changes throughout the life, the stress is extremely generated in the developer, the spent of the carrier, the coating is peeled off, the torque of the stirring roller in the developing tank is abnormal, and the life cannot be guaranteed. For this reason, it is understood that it is necessary to coat the carrier thickly with silicon and to make appropriate current, carbon amount, toner resistance, and developer charge amount distribution appropriate.

[0054]

As described above, according to the electrostatic charge developer according to the present invention, the current value [Ia] μA of the carrier relative to the current value [Ia] μA of the core material at an applied voltage of 200 V is used.
b] The relationship with μA is 0.18 ≦ [Ib] / [Ia] ≦ 0.
50 and the carrier current [Ib] μA is 10 μA to 5
0 μA and the carrier average particle size is 50 to
Since the thickness is in the range of 100 μm, high image quality, high resolution carrier physical properties are sufficiently maintained, and long life is maintained.

[Brief description of the drawings]

FIG. 1 is a characteristic diagram illustrating a charge amount distribution of a developer when deviations (σ) are 0.6 and 3. FIG.

FIG. 2 is a characteristic diagram illustrating a charge amount distribution of a developer when a deviation (σ) of the present embodiment is 1.5.

FIG. 3 shows that the center value (Mean) is -2.3 and -0.0.
FIG. 3 is a characteristic diagram illustrating a charge amount distribution of a developer in FIG.

FIG. 4 is a graph showing that the central value (Mean) of the present embodiment is -1.2.
FIG. 4 is a characteristic diagram showing a developer charge amount distribution in FIG.

FIG. 5 is a characteristic diagram showing a charge amount distribution of a developer when a reverse charge amount rate (Qn) is 17%.

FIG. 6 is a graph showing that the reverse charge amount rate (Qn) of the present embodiment is 8%.
FIG. 4 is a characteristic diagram showing a developer charge amount distribution in FIG.

FIG. 7 is a characteristic diagram illustrating a charge amount distribution of a developer having two peaks.

FIG. 8 is a characteristic diagram showing a charge amount distribution of the developer in which one peak (peak) of the present embodiment is shown.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takahiro Bito 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (72) Inventor Toshihisa Ishida 22-22, Nagaike-cho, Abeno-ku, Osaka-shi, Osaka (72) Inventor Yoshiaki Akazawa 22-22 Nagaikecho, Abeno-ku, Osaka City, Osaka Prefecture F-term (reference) 2H005 AA00 BA02 BA06 CA12 CB02 EA01 EA05 EA10 FA01 2H031 AC15 AD09 BA08 BA09 BB01 BB05 2H068 AA54 2H077 AA39 AD02 AD06 AE08 BA03 EA03 GA17

Claims (6)

[Claims] 1. A two-component developer comprising an iron-based powder as a core material and a carrier coated with silicon on its surface and a toner, the current value [Ia] μA of the core material at an applied voltage of 200 V Current value of the carrier [Ib] μA
Is 0.18 ≦ [Ib] / [Ia] ≦ 0.50
And the carrier current value [Ib] μA is 10 μA to 5 μA.
0 μA and the carrier average particle size is 50 to
An electrostatic charge developer having a range of 100 μm. 2. The electrostatic charge developer according to claim 1, wherein
Silicon carbon content (Csi)% is 0.15 (%) ≦ Csi
An electrostatic charge developer characterized by being in the range of ≦ 0.30 (%). 3. The electrostatic charge developer according to claim 1, wherein the toner has a dielectric loss value (tan δ) and a resistance value (R) of 2.0 × 10 ⁻³ ≦ tan δ ≦ 3.5 ×. An electrostatic developer characterized by being in the range of 10 ^-3 and 200 × 10 ⁹ (Ω) ≦ R ≦ 290 × 10 ⁹ (Ω). 4. The electrostatic charge developer according to claim 1, wherein a deviation value (σ) and a center value (Mean) in a charge amount distribution of a start developer in which the carrier and the toner are mixed. , And the reverse charge amount ratio (Qn: [positive charge amount number] × 100 / [negative charge amount number + positive charge amount number])
0.8 ≦ σ ≦ 2.0, −2.0 ≦ Mean ≦ −0.7, and Qn ≦ 15.0, and shows one peak in the output charge amount distribution diagram. An electrostatic charge developer comprising: 5. A digital image forming method using the electrostatic charge developer according to claim 1, wherein the resolution is 600 dpi or more, and the volume average particle diameter of the toner is 6.0 to 10.0 μm. Using the toner within the range described above, using a counter method as a developing method, and setting the drum diameter to 35.
φ or less, process speed 61mm / sec-122mm / s
An image forming method, wherein the process speed is selected within the range of ec, and the process speed is output by changing the resolution. 6. A digital image forming apparatus using the electrostatic charge developer according to claim 1, wherein the resolution is 600 dpi or more, and the volume average particle diameter of the toner is 6.0 to 10.0 μm. Wherein the developing system is a counter system, the drum diameter is 35 mm or less, and the process speed is selected within the range of 61 mm / sec to 122 mm / sec.