JPH10171167A - Electrophotographic two-component developer and electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a change in the quantity of electric charges due to an environmental change and to form a stable image without varying image density or causing fog by using a specified toner and a specified magnetic carrier. SOLUTION: This electrophotographic two-component developer consists of a toner obtd. by adding fine silica particles coated with polysiloxane contg. constituent units represented by formula II to colored particles contg. a colorant and a compd. represented by formula I in a bonding resin in a dispersed state and a carrier obtd. by coating the surfaces of magnetic particles with polyolefin resin. In the formula I, each of R1 and R2 is 8-22C long chain alkyl, etc., R3 is 1-4C alkyl, R4 is 1-4C alkyl or benzyl and [A]<-> is an Mo<-> or W-contg. anion. In the formula II, R5 is H, hydroxy, etc., R6 is a bonding group or a simple bonding radical, each of R7 -R9 is H, alkyl, etc., and X<-> is halogen.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-component developer for electrophotography (hereinafter simply referred to as a developer) and an electrophotographic apparatus using the developer.

[0002]

2. Description of the Related Art Conventionally, an image density detection method and a magnetic permeability detection method have been mainly used for controlling the toner concentration of a developer used in an electrophotographic apparatus.

In the image density detection method, an electrostatic latent image of a reference density pattern is formed outside an image forming area of a photoreceptor by an optical system, and is developed under a predetermined condition to form a toner image of the reference density pattern. In this method, the toner density is controlled based on a detection signal obtained by detecting the reflection density of the toner image so that the image density becomes constant. In the above image density detection method, in a low humidity environment, when the charge amount of the toner is likely to increase, the toner density is increased to control the toner charge amount so as not to increase. In the case where the charge amount of the toner tends to decrease, the toner density is reduced so that the charge amount of the toner is controlled not to decrease.

For this reason, even if the charging ability of the developer changes due to the environment, it is automatically corrected to some extent, the charge amount is kept almost constant, and there is an advantage that the influence of the environmental change of the charging ability on the image is small. is there.

However, in a low-humidity environment, the toner concentration may be too high. In such a case, the number of charge sites of the carrier is reduced, causing problems such as toner scattering and fogging.

In a high-humidity environment, the toner density may be too low. In this case, a necessary image density of the solid portion can be obtained, but a high-quality image with poor reproducibility of fine lines can be obtained. There is no problem.

On the other hand, the magnetic permeability detection method is a method of directly measuring the toner density by measuring the magnetic permeability of a developer in a developing device and controlling the toner density itself to be constant. If the performance changes depending on the environment, there is a drawback that the image appears as a change in the image as it is. Further, there is a disadvantage that the change in the charge amount changes the bulk density of the developer, and the magnetic permeability changes even with the same toner concentration, so that the toner concentration cannot be correctly controlled.

For example, when the charge amount tends to increase in a low-humidity environment, the bulk density of the developer decreases, and the magnetic permeability decreases, so that the toner concentration tends to be reduced. Therefore, the result is that the charge amount of the toner is further increased and the image density is reduced. or,
When the charge amount tends to decrease in a high humidity environment, the bulk density of the developer increases, and therefore the magnetic permeability increases, so that the toner concentration tends to be increased. Therefore, the charge amount of the toner is further reduced, and fogging is likely to occur.

As described above, even if the toner density is controlled by any of the image density detection method and the magnetic permeability detection method, if the environment dependency of the developer is large, the fluctuation of the image density and the fog Due to problems such as generation, a high-quality image cannot be stably obtained, and development of a developer excellent in environmental resistance has been desired.

In addition, even if the toner density is controlled by the magnetic permeability detection method, which is conventionally considered to have a large fluctuation in image quality due to a change in the charging ability of the developer, problems such as fluctuation in image density and occurrence of fogging do not occur. It has been desired to develop a developer capable of stably obtaining a high quality image.

[0011]

SUMMARY OF THE INVENTION The present invention has been proposed in view of the above circumstances, and has as its object the fact that the amount of charge does not change due to a change in the environment. An object of the present invention is to provide a developer capable of obtaining a stable image without fluctuation of image density and occurrence of fog.

Still another object is to provide a high-quality image forming apparatus which does not cause a problem such as a fluctuation in image density and generation of fogging even when an image is formed by controlling the toner density of a developer using a sensor of a magnetic permeability detection system. An object of the present invention is to provide an image forming apparatus capable of stably obtaining an image.

[0013]

The above object of the present invention is attained by the following constitutions.

1. Colored particles obtained by dispersing and containing a colorant and a compound (A) represented by the following general formula (1) in a binder resin are coated with a polysiloxane containing a structural unit represented by the following general formula (2). A two-component developer for electrophotography, comprising: a toner obtained by externally adding the silica fine particles (B) thus prepared; and a carrier whose magnetic particles are coated with a polyolefin resin.

[0015]

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(Wherein R ₁ and R ₂ each independently represent a long-chain alkyl group having 8 to 22 carbon atoms or a long-chain alkenyl group having 8 to 22 carbon atoms, and R ₃ represents an alkyl group having 1 to 4 carbon atoms) R ₄ represents an alkyl group having 1 to ₄ carbon atoms or a benzyl group, and [A] ⁻ represents an anion containing a molybdenum atom or an anion containing a tungsten atom.)

[0017]

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(Wherein R ₅ represents a hydrogen atom, a hydroxy group, an alkyl group, an aryl group, an alkoxy group, or a group having the following structure:

[0019]

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[0020] R ₆ represents a linking group or a single bond R _7,
R ₈ and R ₉ each represent a hydrogen atom, an alkyl group or an aryl group, X ⁻ represents a halogen atom, and each of the groups represented by R _{5 to} R ₉ may have a substituent. ) 2. An electrophotographic apparatus having a toner density sensor of a magnetic permeability detection type that detects a change in a mixing ratio of a toner of an electrophotographic two-component developer and a magnetic carrier in a developing device as a change in magnetic permeability. An electrophotographic apparatus using the two-component developer for electrophotography described in 1 above as a two-component developer for electrophotography.

Hereinafter, the configuration of the present invention will be described in detail.

The developer according to the present invention is characterized in that the coloring agent, the charge controlling agent represented by the general formula (1), and the releasing agent, if necessary, are dispersed and contained in the binder resin. From a silica fine particle coated with a polysiloxane containing a structural unit represented by the formula (2), a toner externally added with resin fine particles or inorganic fine particles as necessary, and a magnetic carrier coated with a polyolefin resin. Be composed.

[Construction of Toner] <Binder Resin> Examples of the binder resin used in the above toner include polyester resin, styrene-alkyl acrylate resin, styrene-alkyl methacrylate resin, styrene-butadiene resin, Styrene-acrylonitrile resin, styrene-acrylic polyester resin,
Styrene-acrylic-crystalline polyester graft resin, polyurethane resin, epoxy resin, silicone resin, polyvinyl chloride, polyamide, polyvinyl butyral, rosin, modified rosin, phenol resin, xylene resin and the like.

In order to achieve the object of the present invention, styrene-alkyl acrylate resins and styrene-alkyl methacrylate resins are particularly preferred.

<Colorant> Examples of the colorant include carbon black, chrome yellow, Dupont oil red, quinoline yellow, phthalocyanine blue, and magnetic substances. Ferromagnetic metals or alloys, such as iron, cobalt, nickel, etc., such as ferrite and magnetite, or compounds containing these elements, or ferromagnetic elements that do not contain ferromagnetic elements but are subjected to appropriate heat treatment Alloys, such as manganese-copper-aluminum and manganese-copper-tin, which are referred to as Heusler alloys containing manganese and copper. The content of the coloring agent in the colored fine particles is preferably 1 to 20% by weight, more preferably 3 to 15% by weight, based on the binder resin.

<Charge Control Agent> In the general formula (1), examples of the long-chain alkyl group corresponding to R ₁ and R ₂ include:
Octyl, decyl, dodecyl, tetradecyl,
Examples include a hexadecyl group, an octadecyl group, an eicosyl group, a docosyl group, an oleyl group, and a hexadecesyl group. Among them, a long-chain alkyl group having 12 to 18 carbon atoms is preferable. Examples corresponding to R ₃ include a methyl group, an ethyl group, a propyl group, a butyl group, a β-hydroxyethyl group, and the like. Examples corresponding to R ₄ include a methyl group, an ethyl group, a propyl group, a butyl group, a β-hydroxyethyl group, a benzyl group and the like.

[0027] [A] ^- is an anion containing an anion, or tungsten atoms containing molybdenum atoms, the anion [A] ^- Examples of the molybdate,
Examples include anions such as tungstic acid, phosphomolybdic acid, silicomolybdic acid, phosphotungstic acid, silicotungstic acid, phosphotungsten / molybdic acid, silicotungsten / molybdic acid, and chromium / molybdic acid.

Among the compounds represented by the general formula (1),
Examples of particularly suitable compounds include the following compound (A-1)
And (A-2).

[0029]

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The amount of the charge control agent represented by the general formula (1) to the binder resin is preferably 0.1 to 5.0 parts by weight, more preferably 0.1 to 5.0 parts by weight, based on 100 parts by weight of the binder resin. If the amount is less than the weight part, the charge amount may be too low,
If the amount is more than 5.0 parts by weight, the developer may be released from the binder resin and adhere to the surface of the carrier to contaminate it, and the developer may not be able to obtain a desired chargeability. Furthermore, it is preferable to add in the range of 0.2 to 2.0 parts by weight.

<Silica Fine Particles> The silica fine particles to be treated with the polysiloxane described below are fine particles having a Si—O—Si bond, and may be manufactured by either a dry method or a wet method. The silica fine particles produced by the vapor phase oxidation of a silicon halide are particularly preferred. Also,
As the silica fine particles, in addition to silicon dioxide (silica), fine particles made of silicates such as aluminum silicate, sodium silicate, calcium silicate, potassium silicate, zinc silicate and magnesium silicate may be used. ,
Those containing 85% by weight or more of SiO ₂ are preferable. In addition,
The primary particles of the above silica (particles separated into individual unit particles) preferably have a diameter of 3 to 2000 nm, more preferably 5 to 500 nm.

<Polysiloxane> The polysiloxane containing the structural unit represented by the general formula (2) used for treating the above silica fine particles has an ammonium salt as a functional group, and is treated with the polysiloxane. The fine particles can impart fluidity and environmental resistance to the toner. Among the polysiloxanes, a polysiloxane represented by the following general formula (3) is particularly preferred.

[0033]

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(Wherein R ₁₀ and R ₁₁ each represent a hydrogen atom, a hydroxy group, an alkyl group, an aryl group or an alkoxy group, and these groups may have a substituent.
_{5 to} R ₉ and X ⁻ have the same meanings as in “Formula 5”. m and n are 1
Represents the above integer. The following are specific examples of the quaternary ammonium ion containing R _{6 to} R ₉ of Chemical Formula 5 and the counter ion X ⁻ .

[0035]

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[0036]

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[0037]

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As a method for obtaining a polysiloxane having an ammonium salt as a functional group, an organohalogenated silane having an ammonium salt as a functional group and, in particular, an organohalogenated silane having no ammonium base are used in a polymerization step. It can be obtained by a method of introducing by polymerization, a method of partially modifying a polysiloxane obtained by polymerization using an organohalogenated silane with an organic group having an ammonium salt as a functional group, or the like. Here, an organoalkoxysilane may be used instead of the organohalogenated silane. In addition, some compounds can be obtained as commercial products.

As a method for treating the surface of the silica fine particles with the polysiloxane having an ammonium salt as a functional group, a known technique can be used. Specifically, for example, a solution prepared by dissolving the polysiloxane in a solvent is used. After dispersing the silica fine particles therein, the solvent is removed by filtration or spray drying, and then dried and cured by heating, or using a fluidized bed apparatus, a solution in which the polysiloxane is dissolved in the solvent is used. A method of spray-coating silica and then drying by heating to remove the solvent to form a film can be used.

The amount of the silica fine particles treated with the polysiloxane is preferably 0.1 to 5 parts by weight, more preferably 0.2 to 5 parts by weight, based on 100 parts by weight of the colored particles.
Preferably it is 2 parts by weight.

<Releasing Agent> Examples of the releasing agent include low molecular weight polyethylene, low molecular weight polypropylene, low molecular weight polypropylene having a number average molecular weight (the number average molecular weight is a polystyrene molecular weight converted value by high temperature GPC) of 1500 to 5000. Polyolefin waxes such as polyethylene-polypropylene copolymers, for example, high melting point paraffin waxes such as microwax, Fischer-Tropsch wax, ester waxes such as fatty acid lower alcohol esters, fatty acid higher alcohol esters, fatty acid polyhydric alcohol esters, and amide waxes Etc. can be used.

<Inorganic Fine Particles and Resin Fine Particles> In addition to the silica fine particles treated with the above polysiloxane, various inorganic fine particles or resin fine particles for improving the chargeability and fluidity of the toner are included in the toner of the present invention. May be added.

Examples of the inorganic fine particles include silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, cerium oxide, antimony trioxide, zirconium oxide, silicon carbide, and silicon nitride. And the like. These may be used after being made hydrophobic, and particularly, titanium oxide which has been made hydrophobic is preferable. As the hydrophobizing agent, various known silane coupling agents, titanium coupling agents, aluminum coupling agents, silicone oils and the like can be used. Particularly, in order to achieve the object of the present invention, methyltrimethoxysilane, phenyl Trimethoxysilane, hexyltrimethoxysilane, and decyltrimethoxysilane are preferred.

As the resin fine particles, generally, vinyl resin fine particles are preferable, because they can be easily produced by a production method such as an emulsion polymerization method or a suspension polymerization method. . Specifically, styrene,
o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-chlorostyrene,
3,4-dichlorostyrene, p-phenylstyrene, p
-Ethylstyrene, 2,4-dimethylstyrene, pt
-Butylstyrene, pn-hexylstyrene, pn
-Octyl styrene, pn-nonyl styrene, pn
Styrene or a styrene derivative such as -decylstyrene, pn-dodecylstyrene, methyl methacrylate,
Ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate,
Methacrylate derivatives such as lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, acrylic Acrylate derivatives such as isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, phenyl acrylate, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, and the like constitute resin fine particles. It can be mentioned as a material. These can be used alone or in combination.

Examples of the material constituting the resin fine particles include olefins such as ethylene, propylene and isobutylene; halogen-based vinyls such as vinyl chloride, vinylidene chloride, vinyl bromide and vinyl fluoride; vinyl propionate; Vinyl, vinyl esters such as vinyl benzoate, vinyl ethers such as vinyl methyl ether and vinyl ethyl ether, vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and vinyl hexyl ketone, N-vinyl carbazole, N-vinyl indole,
N-vinyl compounds such as N-vinylpyrrolidone, vinyl compounds such as vinylnaphthalene and vinylpyridine, acrylonitrile, methacrylonitrile, acrylamide, N
And acrylic acid or methacrylic acid derivatives such as -butylacrylamide, N, N-dibutylacrylamide, methacrylamide, N-butylmethacrylamide and N-octadecylacrylamide. These vinyl monomers can be used alone or in combination.

The toner of the present invention is obtained by appropriately mixing raw materials including the above colorant, binder resin, charge control agent, release agent, etc., and mixing, melting, cooling, pulverizing and classifying to obtain colored particles. Alternatively, the above-mentioned raw materials can be dissolved in a solvent, and colored particles can be obtained by a method of dispersing and polymerizing the particles.The colored particles may be treated with an external additive such as silica, resin fine particles, or inorganic fine particles treated with the polysiloxane. It is obtained by adding.

As the external additive, a lubricant such as zinc stearate and polyvinylidene fluoride or a fixing aid such as low molecular weight polypropylene can be used in addition to the silica, resin fine particles, inorganic fine particles and the like.

The average particle size of the toner of the present invention is preferably 3 to 15 μm, more preferably 5 to 10 μm.
The average particle diameter of the toner is represented by a volume average particle diameter when a 100 μm aperture is used using a Coulter counter particle size distribution analyzer TA-II.

The charge amount of the toner of the present invention is adjusted so that an appropriate image density can be obtained and the image quality is not impaired.
４０40 (μC / g).

[Construction of Carrier] Next, as a carrier constituting the developer of the present invention, a carrier in which the surface of magnetic particles is coated with a polyolefin is used.

The monomers constituting the polyolefin include ethylene, propylene, 1-butene, 2-butene,
1-pentene, 2-pentene, 2-methyl-1-butene, 1-hexene, 1-heptene, 1-octene, 1-
Aliphatic hydrocarbon monomers such as nonene are preferred. Resins obtained from other vinyl monomers or copolymer resins can also be used. Preferably, a polyethylene resin using ethylene as a monomer is preferable.

The magnetic particles serving as the core of the carrier are not particularly limited, and preferably have a volume average particle diameter of 20 to 20.
0 μm, more preferably 30 to 100 μm. The composition is ferrite, magnetite, iron powder or the like.

The coating amount of the olefin resin for coating the magnetic particles serving as the core of the carrier is preferably 1 wt% to 20 wt%, more preferably 2.5 wt%, based on the magnetic particles.
wt% to 10 wt%. If the content is less than 1 wt%, the impact may not be sufficient depending on the structure of the developing device. On the other hand, if the content is 20 wt% or more, the film thickness becomes too large and the resistance becomes high, and the image density may decrease depending on the developing conditions (potential, developing gap, etc.).

As the method for producing the carrier of the present invention, various generally known coating methods, for example, a method of dissolving an olefin resin in an appropriate solvent and spray-coating the surface of the magnetic particles are used. A method in which an olefin-based resin powder is adhered and mechanically fixed while heating to a temperature equal to or higher than the melting point of the resin material. Any of the surface polymerization coating methods described in JP-A-60-106808 and the like may be used. .

The surface polymerization coating method is a method in which a so-called Ziegler-Natta catalyst or the like is supported on the surface of magnetic particles serving as nuclei, and the above-mentioned monomer is polymerized from the surface.
This method is preferable because a carrier having excellent adhesion and adhesion to the magnetic material surface can be obtained.

[Construction of Developer] The developer of the present invention comprises a carrier and a toner such that the toner is preferably 1 to 20 parts by weight, more preferably 2 to 15 parts by weight, per 100 parts by weight of the developer. Obtained by mixing.

[Configuration of Image Forming Apparatus] The configuration of an image forming apparatus for forming an image using the developer of the present invention will be described below with reference to FIG.
This will be described with reference to FIGS.

FIG. 1 is a sectional view showing an example of the image forming apparatus of the present invention. In FIG. 1, a photosensitive layer 2 of a photosensitive drum 1 is charged by using a corona discharger 3 and then subjected to imagewise exposure 4. A part of the electric charge is removed to form an electrostatic latent image, and when the developer is brought into contact with the electrostatic latent image, the charged toner 6 develops the electrostatic latent image. Thereafter, the developed toner is transferred to a transfer paper 8 at a transfer pole 7 and further fixed by a fixing roller 9 to form a copy image 1.
It becomes 0. The photoreceptor drum 1 that has completed the transfer step travels again to the corona discharger 3 via the cleaning blade 11.

Here, the developer 5 is mixed with the stirring screw 12
When the magnetic carrier and the toner are uniformly stirred and mixed, frictional charging occurs and the toner adheres to the carrier surface. When this developer 5 is supplied to the surface of the photosensitive drum 1 by a developing roller 14 composed of a magnet via a supply screw 13, the magnetic carrier adheres to the surface of the developing roller 14 in a fluffy form by magnetic force, and the toner adheres to the surface. Thus, a so-called magnetic brush is formed. This magnetic brush is opposed to the photosensitive drum 1, and only the toner is electrostatically attracted and attached by the electrostatic latent image on the photosensitive drum 1. The developer 5 whose toner has been consumed by the development is supplied to the supply screw 13 again.
Then, the process returns to the developer mixing section having the stirring screw 12.

As described above, when the toner concentration in the developer decreases, the toner concentration sensor 15 below the supply screw 13 detects the toner concentration and sends a signal to the toner replenishing tank 16 to replenish the toner. Is kept constant. Inside the toner density sensor, a differential transformer 151 as shown in FIG. 2 is included. Supplying alternating current to the L ₁ of the primary coil of FIG 2 the secondary coil L ₂₁ and L
Induction voltages are generated at ₂₂ (electromagnetic induction). Core 15
If 2 is in the middle, the voltage generated in L ₂₁ and L ₂₂ are equal. Core towards the voltage increases occurring L ₂₁ Moving to L ₂₁ side, toward the voltage developed L ₂₂ Moving to L ₂₂ side increases. Two secondary coils are connected in series so that the polarities are opposite, and rectified to take out a difference between induced voltages.
Since this difference voltage is determined by the position of the core,
If a moving body is connected to 2, the amount of displacement can be detected and used as a position sensor.

Now, consider changing the length of the core instead of moving the core 152. That is, a magnetic material is added on the core. What replaces this magnetic material with a carrier is a toner density sensor. In this case, since the magnetic material (carrier) exists at a position distant from the core (as viewed from the core) at a low density, the toner density change 1
%, Only an output change of about 0.1 V can be obtained. When the core as a phenomenon other than the voltage change moves to L ₂₁ side → central → L ₂₂ side, the phase of the output of the L ₂₁ and L ₂₂ are reversed on the border central. In the toner density sensor, the phase difference is converted into a voltage by a phase discriminating circuit, so that the voltage of the ordinary differential transformer is reduced.
An output of 10 to 10 times is obtained.

FIG. 3 is a diagram for explaining the operation of the toner density sensor 15. The toner density in the developer 5 (comprising the magnetic carrier 20 and the toner 6) conveyed by the developer supply screw 13 is determined by the developer. 5 is measured by the toner density sensor 15 arranged in contact with the toner concentration sensor 5. Since the toner density sensor 15 is a magnetic permeability detection sensor, the conventional developer has a large environmental dependency of the charging ability, and causes an increase in fog at high humidity and a decrease in image density at low humidity, thereby obtaining a high quality image. However, the use of the developer of the present invention makes it possible to obtain a high-quality image stably because the developer has excellent environmental resistance, does not change the charge amount of the developer, and is stable.

[0063]

[Production Example 1 of Toner]

Styrene / n-butyl acrylate / methacrylic acid = 88/11/1 (weight ratio) copolymer 100 parts by weight Carbon black (Black Pearl L; manufactured by Cabot) 10 parts by weight Polypropylene (Viscol 660P; manufactured by Sanyo Chemical Industries) 4 parts by weight Compound (A-1) 1 part by weight The above components were mixed, melted, kneaded, crushed, and classified to obtain colored particles having an average particle size of 8.0 μm.

Further, based on 100 parts by weight of the colored particles, dimethyldichlorosilane was first used, and then the following compound (C)
Of silica having an average particle diameter of 12 nm,
Parts by weight, 0.4 parts by weight of titanium oxide having an average particle diameter of 100 nm surface-treated with hexyltrimethoxysilane, and 0.05 parts by weight of zinc stearate (zinc stearate-S: manufactured by NOF Corporation). . This is referred to as toner 1.

[Toner Preparation Example 2] The toner was prepared in exactly the same manner as in Preparation Example 1 above except that 1.0 part by weight of Aerosil 200 (manufactured by Degussa) was added instead of the surface-treated silica. Produced. This is referred to as toner 2.

[0066]

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[Toner Preparation Example 3] A toner was prepared in exactly the same manner as in Preparation Example 1 of the toner except that the following compound (D) was used in an amount of 1.0 part by weight instead of the compound (A-1). did. This is referred to as toner 3.

[0068]

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[Production Example 1 of Carrier] 100 ml of dehydrated n-heptane and 12 ml of
A slurry is formed by adding 10.0 g (17 mmol) of magnesium stearate which has been dried at 0 ° C. under reduced pressure (2 mmHg). 0.33 g of titanium tetrachloride (1.7
Mmol), and then the temperature is raised. The reaction was carried out under reflux for 2 hours to obtain a viscous and transparent solution of the titanium-containing catalyst component.

Thereafter, 50 ml of dehydrated n-hexane was added to an autoclave having an inner volume of 1 liter and purged with argon at room temperature.
0 ml and magnetite particles previously dried under reduced pressure at 200 ° C. for 3 hours (average particle size: 60 μm)
, And stirring was started. Next, the temperature was raised to 40 ° C., and the above-mentioned titanium-containing polymerization catalyst component was added in an amount of 0.02 mmol as a titanium atom, followed by heat treatment for about 1 hour to obtain a slurry of the mixture.

Then, 0.50 g of carbon black (Ketjen Black EC: manufactured by Lion Akzo Co., Ltd.), which had been dried under reduced pressure at 200 ° C. for 2 hours, was added thereto, and the mixture was further stirred. Thereafter, 2.0 mmol of triethylaluminum and 2.0 mmol of diethylaluminum chloride were added, and the temperature was raised to 90 ° C. The internal pressure at this time was 2.0 kg / cm ² G. Then supplying hydrogen, then boosted to 5 kg / cm ² G, the total pressure was subjected to polymerization for 30 minutes while continuously feeding ethylene to keep the 9.5 kg / cm ² G, the carbon black-containing polyethylene-coated magnetite Particles were obtained.

Thereafter, the mixture was passed through a sieve having an opening of 106 μm to remove aggregates. After that, it was charged into a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.), and the stirring blade had a peripheral speed of 10 m / s.
Stirring was performed for 30 minutes under heating at 60 ° C. to obtain a polyethylene-coated carrier 1. The carrier 1 had a polyethylene resin coating amount of 7.0% by weight.

[Production Example 2 of Carrier] Styrene / methyl methacrylate = 1/9 (molar ratio) copolymer 2.2 parts by weight Core material particles (spherical magnetite particles, average particle size 60 μm) 100 parts by weight Charge the carrier material into a horizontal rotary wing type mixer,
After mixing and stirring at 30 ° C. for 5 minutes under the condition that the peripheral speed of the horizontal rotary blade was 8 m / s, the mixture was heated to 100 ° C. and stirred for 20 minutes to produce a resin-coated carrier. This is called carrier 2.

[Preparation of Developer 1] 5 parts by weight of toner 1 and 95 parts by weight of carrier 1 were mixed to obtain developer 1 for the example.

[Preparation of Developer 2] A developer 2 for comparison was prepared by mixing 5 parts by weight of the toner 2 and 95 parts by weight of the carrier 1.
I got

[Preparation of Developer 3] 5 parts by weight of the toner 3 and 95 parts by weight of the carrier 1 were mixed to prepare a developer 3 for comparison.
I got

[Preparation of Developer 4] 5 parts by weight of the toner 1 and 95 parts by weight of the carrier 2 were mixed to prepare a developer 4 for comparison.
I got

Example 1 A commercially available electrophotographic copying machine "Konica 2120" (Konica Corporation), which controls the toner density of the developer 1 in an environment of 30 ° C. and 80% (relative humidity) by a magnetic permeability detection method. The image after 2,000 copies was evaluated using the above method, and a good image having a high maximum image density of 1.35 and a low fog density of 0.001 was obtained.

When the image of the developer 1 was similarly evaluated after 2,000 copies in an environment of 10 ° C. and 20% (relative humidity) using the above electrophotographic copying machine, the maximum image density was 1.33. A good image having a high fog density and a low fog density of 0.000 was obtained.

It should be noted that the maximum image density is 1.3%.
The reflection relative density of the solid portion, which is 0, and the fog density, the reflection relative density of a white background when the unused paper of the same type as the paper used for image evaluation is set to 0, are determined by a Macbeth densitometer (Divis).
ion of kollmorgen Instrument
ent corporation).

The maximum image density is 1.30 or more, and the fog density is 0.010 or less.

Comparative Example 1 The same evaluation as in Example 1 was carried out for the developer 2 for comparison. In an environment of 30 ° C. and 80% (relative humidity), the maximum image density was as high as 1.40, but the image density was high in the white portion. Fog occurred and the fog density was 0.015. 10 ° C2
In an environment of 0% (relative humidity), the maximum image density was as low as 1.11.

Comparative Example 2 A comparative developer 3 was prepared and evaluated in the same manner as in Example 1. Table 1 shows the evaluation results.

Comparative Example 3 A comparative developer 4 was prepared and evaluated in the same manner as in Example 1.

Table 1 shows the evaluation results.

[0086]

[Table 1]

According to Table 1, in Example 1, the required maximum image density was obtained irrespective of the change in humidity, and the fog density was extremely small and excellent. The fog density at the time of reduction and high humidity is large,
It turns out that it is not practical.

[0088]

As has been demonstrated in the examples, according to the developer and the electrophotographic apparatus of the present invention, the charge amount does not change even when the environment changes, and the image density changes when an image is formed. , And a stable image can be obtained without fogging. Further, even when the image formation is performed by controlling the toner concentration of the developer using a sensor of the magnetic permeability detection method, the fluctuation of the image density and the fog It has excellent effects such as no generation and stable images.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of an image forming apparatus of the present invention.

FIG. 2 is a diagram showing a differential transformer.

FIG. 3 is a diagram illustrating the operation of a toner density sensor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Photoconductor drum 2 Photosensitive layer 3 Corona discharger 5 Developer 6 Toner 7 Transfer pole 8 Transfer paper 9 Fixing roller 10 Copy image 11 Cleaning blade 12 Stirring screw 13 Supply screw 14 Developing roller 15 Toner density sensor 16 Toner supply tank 20 Carrier 151 differential transformer 152 core L ₁ 1 primary coil L _21, L ₂₂ 2 coil

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI G03G 9/10 351 (72) Inventor Kenji Yamane 2970 Ishikawacho, Hachioji-shi, Tokyo Konica Corporation

Claims (2)

[Claims] Claims 1. A colored particle comprising a binder resin and a colorant and a compound (A) represented by the following general formula (1) dispersed and contained therein, a structural unit represented by the following general formula (2): A two-component developer for electrophotography, comprising: a toner obtained by externally adding silica fine particles (B) coated with a polysiloxane containing the same; and a carrier having magnetic particle surfaces coated with a polyolefin resin. Embedded image (Wherein R ₁ and R ₂ each independently represent a long-chain alkyl group having 8 to 22 carbon atoms or a long-chain alkenyl group having 8 to 22 carbon atoms, and R ₃ represents an alkyl group having 1 to 4 carbon atoms. , R ₄ represents an alkyl group having 1 to ₄ carbon atoms or a benzyl group,
[A] ^- is an anion containing an anion, or tungsten atoms containing molybdenum atoms. ) (Wherein R ₅ represents a hydrogen atom, a hydroxy group, an alkyl group, an aryl group, an alkoxy group, or a group having the following structure; R ₆ represents a bonding group or a mere bond, and R ₇ , R ₈ and R ₉
Each hydrogen atom, an alkyl group or an aryl group, X ^- represents a halogen atom, each group represented by R ₅ to R ₉ may have a substituent. ) 2. An electrophotographic apparatus having a toner density sensor of a magnetic permeability detection type for detecting a change in a mixing ratio of a toner and a magnetic carrier of a two-component developer for electrophotography in a developing device as a change in magnetic permeability. 2. An electrophotographic apparatus, wherein the electrophotographic two-component developer according to claim 1 is used as the electrophotographic two-component developer in the developing device.