JPH0470879A - Electrophotographic developing method - Google Patents

Abstract

PURPOSE:To completely stir developer even by a screw type mixing and stirring member by using resin coated carrier having many pores on its surface. CONSTITUTION:The two-component developer used in a developing device 1A is constituted of the resin coated magnetic carrier 21 and toner 25. The carrier 21 is constituted of a carrier core material 22 and a resin coating layer 23, and the pores 24 are formed on the surface of the layer 23. Then, the two- component developer in the device 1A circulates in a direction shown by an arrow without getting over a partitioning wall 4, while the carrier 21 and the toner 25 are mixed and stirred, the lump of the toner is crushed and the toner 25 is stuck to the carrier 21 because it is triboelectrified with the carrier 21. Meanwhile, a developing sleeve 51 carries the carrier 21 to which the toner 25 is stuck by the action of a magnet body 52 on an inner side to a developing area while holding it in a napping state.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is an electrostatic latent image formed on an image bearing member of an electrophotographic copying machine, printer, etc. by two-component development consisting of a magnetic carrier and toner. The present invention relates to an electrophotographic developing method for producing a visible image using an agent.

[Conventional technology]

This type of development method is widely known, in which the toner is charged by mixing and stirring the carrier and toner in the developer, and the carrier is transported together with the charged toner to the development area by a developing sleeve with a built-in magnet. Therefore, the charged toner is attached to the electrostatic latent image on the image carrier.

The mixing and agitation of the carrier and toner is generally performed using a bucket type agitation member.

However, today, there is a desire to make copying machines, printers, etc. smaller and more compact, and along with this, there is a demand for smaller and more compact developing devices. There is a demand for devices to be smaller and more compact.

What governs the miniaturization and compactness of the developing device is its mixing and agitating mechanism, and if the bucket type is used, there is a limit to the miniaturization and compactness.

As a way to solve this problem,
It is conceivable to use a developing device that employs a screw type mixing and stirring member as disclosed in Publication No. 3 and the like.

[Problems to be Solved by the Invention] However, the screw type mixing and stirring member has inferior mixing and stirring ability compared to the bucket type one, and when a commonly used two-component developer is used, the mixing and stirring performance is poor. , toner charging rises insufficiently, resulting in problems such as fogging and toner scattering, especially in the final image.

Therefore, the present invention provides an electrophotographic developing method for developing an electrostatic latent image on an image bearing member using a two-component developer consisting of a magnetic carrier and a toner, which can achieve miniaturization and compactness of the developing device. Moreover, it is an object of the present invention to provide a method in which the carrier and toner are mixed well, the toner charge rises well, and problems such as toner fog and toner scattering are less likely to occur.

[Means for Solving the Problems] The method of the present invention for achieving the above object is an electrophotographic developing method in which an electrostatic latent image on an image carrier is developed using a two-component developer consisting of a magnetic carrier and a toner. The carrier and toner are mixed and stirred using a screw-type mixing and stirring member, and the carrier is a resin-coated carrier having a large number of pores on the surface.

(Function) According to the method of the present invention, since the magnetic carrier in the two-component developer has the above-mentioned large number of pores on its surface, the magnetic carrier and toner are sufficiently stirred even by a screw type mixing stirring member, and the toner rises. It is well charged and desired development is performed with little or no toner fog or toner scattering.

[Example〕 Hereinafter, an example of the method of the present invention will be explained with reference to the drawings.

FIGS. 1 and 2 show an example of a developing device used to carry out the method of the present invention. FIG. 1 shows a horizontal cross section of the developing device, and FIG. 2 shows a cross section perpendicular to the width direction of the developing device.

This developing device IA has a casing 1 with an opening on the negative side, and a developing sleeve 51 is disposed in the opening and rotatably supported by the casing 1.

A magnet body 52 is fixedly arranged inside the developing sleeve 51 . A partition wall 4 is erected behind the developing sleeve 51, and both ends of the wall are spaced apart from the casing side walls 11,11.

Screw-type mixing and stirring members 2.3 are disposed in front and behind the partition wall 4, the conveying directions of mixing and stirring blades of these members are opposite to each other, and these members are rotatably supported by the casing 1. Various shapes of stirring blades for the member 2.3 can be considered, such as those with a full circumference, half circumference, and 2/3 circumference of the shaft.

A toner powder smoke prevention plate 8 is disposed above the developing sleeve 51 and is supported by the upper part 12 of the casing 1 so as to partially close the casing opening.

Behind the plate 8 is a height regulating Fi, 7 is a developing sleeve 51.
It is supported by the upper part 12 of the casing 1 so as to face the upper part 12 of the casing 1. Casing side wall 11 facing one end of the mixing and stirring member 2
A toner replenishing port 6 is provided in the toner replenishing port 6, and toner is supplied from a toner replenishing means (not shown).

This developing device IA is installed in the main body of the image forming apparatus (not shown) with the left side at the back and the right side at the front in FIG. Up, rotationally driven clockwise CW.

A two-component developer, which will be described later, stored in the casing circulates in the direction of the arrow in FIG. is charged by friction with the carrier and adheres to the carrier. On the other hand, the developing sleeve 51 holds the carrier to which the toner is attached in the form of a spike by the action of an internal magnet 520 and transports it to the developing area. In the developing area, the toner on the carrier adheres to the electrostatic latent image on the image bearing member (photoreceptor drum PC in this case) of the image forming apparatus under the application of a developing bias voltage to the developing sleeve 51. is developed to form a visible image.

The obtained visible image (toner image) is transferred to transfer paper and fixed.

FIG. 3 shows another example of a developing device used to carry out the method of the present invention.

This developing device IB includes a partition wall 40.40 in place of the partition wall 4 of the developing device IA shown in FIGS. 1 and 2, and a mixing and stirring member 20.30 in place of the mixing and stirring member 2.3.
and a toner supply port 9.10 in place of the toner supply port 6.
In other respects, it has the same configuration as the apparatus shown in FIGS. 1 and 2.

The partition walls 40.40 are arranged at a distance from the casing side walls 11.11, and there is also a distance between the partition walls.

The mixing and stirring member 20 includes screw-type blades 201 and 202 whose developer transport directions are opposite to each other, and the member 30
The screw type blades 301 and 302 are also provided with developer conveying directions opposite to each other. Feathers 201 and 30
1. The developer transport directions of the blades 202 and 302 are also opposite to each other. Various shapes of the stirring blades of the members 20 and 30 are conceivable, such as those with a full circumference, half circumference, and 2/3 circumference of the shaft.

The toner supply ports 9 and 10 are provided in the casing 1 at positions facing both ends of the mixing and stirring member 20.

Other possible toner replenishment modes include, for example, line replenishment.

According to this developing device, the two-component developer in the casing 1 is circulated in the direction of the arrow in FIG. The toner mass is crushed, and the toner is charged by friction with the carrier and adheres to the carrier. On the other hand, the developing sleeve 51 holds the carrier to which the toner is attached in the form of a spike by the action of the internal magnet 52 and transports it to the developing area. In the development area, toner on the carrier adheres to the electrostatic latent image on the image carrier PC under application of a development bias voltage to the development sleeve 51, and this is developed to form a visible image. The resulting visible image (toner image) is transferred to transfer paper and fixed.

Note that the developing device for carrying out the method of the present invention is not limited to the one described above.

(This page, hereafter in the margin) Next, the two-component developer used in the developing devices IA and IB will be explained. This developer consists of a resin-coated magnetic carrier and toner.

First, the resin-coated carrier will be explained.

For ease of understanding, a schematic cross-sectional view of a resin-coated carrier used in the method of the present invention is shown in FIGS. 4 and 5, and a schematic cross-sectional view of a conventional resin-coated carrier is shown in FIG. Ta.

The resin-coated carrier 21 used in the method of the present invention consists of a carrier core material 22 and a resin coating layer 23 covering the core material, and pores 24 are formed on the surface of the resin coating layer. Compared to the conventional carrier 26 shown in FIG. 6 which has a resin coating layer 28 on a core material 27, the presence of pores 24 is a major feature.

In developing the electrostatic latent image, since the pores 24 are present on the surface of the resin-coated carrier 21, sufficient mixing contact between the toner particles 25 and the carrier particles 21 can be ensured. , the charge rise of the toner is quick, and each toner particle can be charged sufficiently uniformly, and toner scattering due to charging failure can be prevented. When the toner passes through a magnetic permeability sensor (not shown), it is charged to a predetermined charging state, and the sensor can always measure the carrier magnetic permeability under a substantially constant toner charge amount. done accurately.

Further, the pores 24 on the surface of the carrier 21 are formed by the toner particles 2.
5 has excellent capture properties, and from this point of view as well, it is effective in preventing toner scattering.

Furthermore, due to the presence of the pores 24, frequent contact between the toner 25 and the carrier 21 occurs, which is effective in preventing toner aggregation and also in breaking up the agglomerated toner. The problem of toner aggregation is solved.

The pores on the surface of the resin-coated carrier 21 are specifically defined by its pore size distribution, average pore diameter, and total pore volume.

Each pore size present on the carrier surface is 0.001~3μ
m, preferably 0.001 to 2 μm, more preferably 0
．． It is desirable that the thickness be distributed in the range of 0.005 to 2 μm. If the pore diameter is smaller than 0.001 μm, it is thought that the effect of the pores will be difficult to manifest from the viewpoint of the crushability of the toner. If it is larger than 3 μm, the toner trapping property is too strong,
This causes a decrease in fluidity and developability.

The average pore diameter is approximately 0.1 to 0.5 μm, corresponding to the pore diameter distribution range described above. Therefore, within this range,
It is thought that the toner exhibits good disintegration properties and good charging characteristics for the toner.

In the present invention, the total pore volume is defined as the total pore volume per carrier Ig (ml!/g) and the coating resin layer 1 m! Expressed in two ways: total pore volume per unit (ml/ml).

The total pore volume per gram of carrier (W11/g) can be determined by mercury porosimetry.

In the carrier used in the method of the present invention, the value is
0.001-0.1 ml/g, preferably 0.0
1～0゜05mj! /g is desirable. If the value is less than 0.001 ttdl/g, there are insufficient pores on the carrier surface and the effect of the pores may not be obtained, and if it is larger than 0.1 dlg, there are too many pores. The coating layer becomes brittle.

The total pore volume (ml) per 1 ml of the coating resin layer can be determined by converting the total pore volume (m27 g) per 1 g of the carrier described above from the true specific gravity of the coating layer and the carrier core material filling rate. can.

In the carrier used in the method of the present invention, the value is 0.1 to 2 m! / 0.5-1.5-
/ Preferably a relative. If the value is smaller than 0.1 mρ/-, there are insufficient pores on the carrier surface, and the effect of the pores may not be obtained.
If it is larger than a goose, there will be too many pores and the coating layer will become brittle.

Next, the constituent materials of the carrier 2I will be explained.

As the carrier core material 22 which is a component of the carrier 21, from the viewpoint of preventing carrier adhesion (scattering) to the photoreceptor 1,
A particle size of at least 20 μm (average particle size) is used, and a particle size of at most 100 μm is used to prevent deterioration of image quality such as generation of carrier streaks. Specific materials include those known as two-component carriers for electrophotography, such as metals such as ferrite, magnetite, iron, nickel, and cobalt, and these metals and zinc, antimony, aluminum, lead, tin, bismuth, beryllium, and manganese. , alloys or mixtures with metals such as selenium, tungsten, zirconium, and vanadium; metal oxides such as iron oxide, titanium oxide, and magnesium oxide; nitrides such as chromium nitride and vanadium nitride; and carbides such as silicon carbide and tungsten carbide. and ferromagnetic ferrite, and mixtures thereof.

Examples of carrier coating resins include polystyrene resins, poly(meth)acrylic resins, polyolefin resins, polyamide resins, polycarbonate resins, polyether resins, polysulfinic acid resins, polyester resins, epoxy resins, and polybutyral resins. resin, urea resin,
Various thermoplastic resins and thermosetting resins such as urethane/urea resins, silicone resins, polyethylene resins, and Teflon resins, and mixtures thereof, as well as copolymers, block polymers, graft polymers, and Polymer blends and the like are used. Furthermore, in order to improve charging properties, resins having various polar groups may be used.

In particular, if the toner used in combination with the carrier is a toner with a small particle size, the smaller the particle size of the toner, the smaller the heat capacity of the toner and the more likely it is to become spent.
In such a case, from the viewpoint of preventing spent, a coating resin with good mold releasability, such as a silicone resin or a polyolefin resin, is preferable.

It is preferable that the surface of the carrier 21 is covered with the carrier coating resin by 70% or more, preferably 90% or more, more preferably 95% or more. When the coverage rate is less than 70%,
The characteristics of the carrier core material itself (unstable environmental resistance, decreased electrical resistance, unstable charging) are clearly visible through the skin.
The advantages of resin coating cannot be taken advantage of.

The filling rate of the carrier core material is set to about 90 wt% or more, preferably 95 wt% or more. The filling rate can be interpreted as indirectly regulating the thickness of the resin coating layer of the carrier, and if the carrier filling rate is less than 9 Qwt%, the coating layer becomes too thick and it is difficult to actually apply it to the developer. However, it does not satisfy the durability and charge stability required of the developer, such as peeling off of the coating layer and increase in the amount of charge.In addition, in terms of image quality, the reproducibility of fine lines is poor, the image density decreases, etc. A problem arises.

It is also possible to express the resin coating layer thickness indirectly by specific gravity. The specific gravity of the carrier 21 is greatly influenced by the type of carrier core material, but as long as the carrier core material is used, 3.
It shows a value within the range of about 5 to 7.5, preferably 4.0 to 6.0, more preferably about 4.0 to 5.5. If the value is outside this range, the same disadvantages as those caused by a carrier that is not coated with an appropriate filling rate as described above will occur.

The electrical resistance of the resin-coated carrier 21 is 1×10 6 to 1×
1014Ω・0, preferably 10s to 1013Ω-cm
, more preferably set to about 10 9 to 10 I 2 Ω-cm. When the electrical resistance is less than 1×10 6 Ω·cm, carrier development occurs and image quality deteriorates.

On the other hand, if it is larger than 1×10'4 Ω·cm, the toner is excessively charged, making it impossible to obtain an appropriate image density. The electrical resistance can also be viewed as an indirect expression of the resin coverage and carrier filling rate described above.

It is preferable that the carrier 21 further provides unevenness to the resin coating layer. FIG. 3 shows a configuration in which the resin coating layer 23 has irregularities, and the pores 24 are present on the surface of the resin coating layer 23 having the irregularities.

By adding such unevenness to the carrier surface,
A carrier with improved toner charge rise characteristics, toner scattering, toner agglomeration and disintegration properties, etc. can be obtained.

Surface unevenness will be explained in more detail.

The surface unevenness structure of the surface coating layer is expressed by the following formula [1];
The outer periphery represents the outer periphery of the projected image of the carrier particles, and the area represents the average value of the projected area of the carrier particles. ] Shape factor S
The value is preferably within the range of 130 to 200. The S value represents the degree of unevenness on the particle surface, and the greater the degree of unevenness of the surface state, the further the value becomes from 100. The shape factor S can be measured, for example, using an image analyzer (Luzex 5000; manufactured by Nippon Regulator Co., Ltd.); however, in general, when measuring the shape factor S, there is not a large difference depending on the model. It doesn't mean you have to.

Further, additives such as fine particles having a charge imparting function or conductive fine particles may be added to the carrier coating resin layer 23.

Fine particles with a charge imparting function include CrCh, Fez
O:l, Feff Oa, Iro□, Mn0z
, MoO2, NbO□, PtO2, TiO2, TiO3
, Ti3O5, WO2, Vz03, Al2O2, MgO
Specific examples include metal oxides such as 1S ioz , Zr0z , and BeO, dyes such as nigrosine base, and spiron black TRH.

Examples of conductive fine particles include carbon blank, carbon blank such as acetylene black, Sic, TiC,
Carbide such as MoC, ZrC, BN, NbN, TiN,
Examples include nitrides such as ZrN, magnetic powders such as ferrite, and magnetite.

Addition of metal oxides, metal fluorides, and metal nitrides is effective in further increasing chargeability. It is believed that this effect is produced by the synergistic charging effects of each component and the toner due to the contact between the toner and the complex interface composed of these compounds, the coating resin, and the core material.

Addition of carbon black is effective in improving developability and obtaining images with high image density and clear contrast. This is believed to be because the addition of conductive fine particles such as carbon black moderately lowers the electrical resistance of the carrier, allowing charge leakage and accumulation to occur in a well-balanced manner.

One of the characteristics of conventional binder-type carriers is that they have excellent halftone reproducibility and gradation reproducibility, but in the case of resin-coated carriers, gradation can be improved by adding magnetic powder to the resin coating layer. A carrier with excellent reproducibility can be obtained. This is thought to be because the addition of magnetic powder to the resin coating layer results in a surface composition similar to that of the no-ingu type carrier, and the chargeability and specific gravity approach those of the binder type carrier.

Addition of borides and metal carbides has an effect on the rise of charging.

The size, amount, etc. of the additives are not particularly limited as long as they satisfy the various characteristics of the carrier 21, such as pore morphology, coverage, and electrical resistance, which are described in this specification. Regarding the size of the carrier 21, which will be described later, in relation to the preferred manufacturing method of the carrier 21, it is sufficient that the particles have a particle size that can be uniformly dispersed to form a slurry without agglomerating in a resin solution or dehydrated hexane. Specifically, the volume average particle diameter is 2 to 0.001 μm, preferably 1 to 0.
．． The thickness may be about 0.01 μm.

Further, as for the amount of the internal particles added, although the amount cannot be specified in part as described above, it is preferably 0.1 wt% to 60 wt% with respect to the coating resin, preferably O, L.
A suitable range is wt% to 40wt%.

In particular, when the resin coating layer 23 is used with a filling rate set in the range of 90 to 97 wt%, it is preferable to add additives such as fine particles having a charge imparting function or conductive fine particles to the resin coating layer 23. When the filling rate of the carrier is as low as about 90 wt% and the thickness of the coating layer is relatively thick, when continuous copying of fine lines is performed using such a carrier, a gap occurs in which the reproducibility decreases. Such problems are solved by the addition of the above additives.

Next, a method for manufacturing the resin-coated carrier 21 having the pores will be explained. As for the manufacturing method of the carrier 21, if the carrier having the above-mentioned pores can be obtained,
Although not particularly limited, the following two methods are preferably used.

One of the preferred manufacturing methods is to disperse fine particle components soluble in a suitable solvent in advance in a coating resin solution, and after forming the coating layer, the fine particles are immersed in a soluble solvent to elute the soluble fine particle components. A method of forming pores on the surface of the coating layer can be mentioned.

In this method, the pore size is determined by the particle size of the solvent-soluble fine particle component, the degree of dispersion, etc. Further, the coating layer can be formed by a powder capsule method, a spray 1ζ lie method, or the like.

As fine particle components that can be used in this method, there may be mentioned fine particles of metal oxides such as ferrite, halides or hydroxides of alkali metals or alkaline earth metals, transition metal complexes, and the like. It goes without saying that it is necessary to use a solvent that does not dissolve the resin at the same time.

More specifically, for example, a method of eluting ferrite by immersing a carrier having a resin coating layer containing ferrite in an acidic aqueous solution such as hydrochloric acid,
By doing so, pores can be formed on the carrier surface.

Furthermore, when adding the above-mentioned fine particles having a charge imparting function or conductive fine particles, these additives may be added and present in the coating resin solution, or pore-forming particles such as ferrite can be added. The use of particles that function both as electrically conductive fine particles and as conductive fine particles is advantageous from the viewpoint of the manufacturing method and properties.

Another preferable manufacturing method for the carrier 21 is a surface polymerization coating method.

The surface polymerization coating method uses: ■ a highly active catalyst component containing titanium and/or zirconium and soluble in a hydrocarbon solvent; ■ a product obtained by contacting a carrier core material in advance; and ■ an organoaluminum compound It can be formed by polymerizing an olefin monomer, such as ethylene, on the surface of the carrier core material. Furthermore, when fine particles having a charge imparting function or conductive fine particles are added, these additives may be added and present at the time of forming the coating layer. Specifically, JP-A-60-1068
The method described in Publication No. 08 is suitable. This publication is hereby incorporated by reference as part of this specification.

When a carrier coating layer is formed by this surface polymerization coating method, in addition to being able to form a coating layer having pores on the surface of the carrier as described above, film strength and
A durable carrier with excellent adhesion between the core particles and the resin coating layer can be obtained.

The toner used in combination with the carrier is:
There are no particular limitations, and the colorant and/or charge-imparting agent can be dispersed in a pulverization method toner or monomer obtained by mixing and kneading a thermoplastic resin, a colorant, and/or a charge-imparting agent, etc., and then crushing and classifying the mixture. , a suspension polymerized toner obtained by polymerizing this, or a liquid containing a low softening point substance such as a colorant and wax, or a fixing resin, etc., is surrounded by a wall material (capsule shell) with a higher softening point than these. Capsule toner wrapped in silica, or photoconductive toner whose surface is coated with a photoconductive substance, and has an average particle size of 3 to 20 μm.
It is possible to use some degree.

Next, manufacturing examples 1 to 3 for manufacturing the uneven carrier 21 shown in FIG. 5, manufacturing examples 4 and 5 for the carrier 21 of the type shown in FIG. 4, and conventional carriers of the type shown in FIG. The production of No. 26 will be explained as Production Example 6.

+1 notice for carrier 1 (1) Adjustment of titanium-containing catalyst component In a flask with an internal volume of 500 m purged with argon, 200 d of n-heptane dehydrated at room temperature and 15 g of magnesium stearate dehydrated in advance at 120°C under reduced pressure (2 mm Hg). (25 mmol) to form a slurry.

Titanium tetrachloride 0.44g (2°3 mmol) with stirring
was added dropwise, and the temperature was gradually raised, and the reaction was carried out for one hour under reflux to obtain a viscous and transparent solution of the titanium-containing catalyst component.

(2) Activity evaluation of titanium-containing catalyst component Internal volume replaced with argon 1! Into an autoclave, 400 d of dehydrated hexane, 0.8 mmol of triethylaluminum, 0.8 mmol of diethylaluminum chloride, and 0.004 mmol of the titanium-containing catalyst component obtained in (1) above were collected and charged as titanium atoms.
The temperature was raised to 90°C. At this time, the system internal pressure is 1.5 kg
/allG. Then, hydrogen is supplied and 5.5
After increasing the pressure to kg/ctjG, the total pressure is 9゜5kg/c
Continuously supply ethylene to maintain 111G,
Polymerization was carried out for 1 hour to obtain 70 g of polymer. The polymerization activity was 365 kg/g-Ti-Hr, and the MFR (melt flowability at 190°C and 2.16 kg of load; JIS K7210) of the obtained polymer was 40.

(3) Reaction of titanium-containing catalyst component and filler and polymerization of ethylene Sintered ferrite powder F- dried in 500 m of dehydrated hexane at room temperature and under reduced pressure (2 anHg) at 200°C for 3 hours in an argon-substituted autoclave with an internal volume of 11. 200(
Manufactured by Powder Chick, volume average particle size 70μm) 450g
was added, 0.02 mmol of titanium atoms of the titanium-containing polymerization catalyst component (1) was added, and the reaction was carried out for about 1 hour. 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 of the system at this time is 1.
5 kg/a! It was G. Next, hydrogen is supplied and 2k
g/c After increasing the pressure to 4 G, the total pressure is increased to 6 kg/c.
Try to keep it on cd G.

Polymerization was carried out for 40 minutes while continuously supplying tyrene, and a total amount of 473 g of a ferrite-containing polyethylene composition was obtained. The dried powder had a uniform gray-white color, and when observed under an electron microscope, the ferrite surface was thinly covered with polyethylene, and no aggregation of ferrite particles was observed in the polyethylene.

In addition, when this composition was measured by TGA (thermal balance), the core material filling rate was 95.2 wt%.

After that, it was placed in a hot air stream set at 120°C and heated to 2°0
Heat treatment was performed for a period of time. The obtained carrier is 106μm
It was classified using a sieve to remove aggregates.

+1 notice of carrier 2 In an autoclave with an internal volume of 11 and replaced with argon, the titanium-containing catalyst component prepared in (1) of Production Example 1 was added to 450 g of ferrite in the same manner as in (3) of Production Example 1. 02 mmol was added and the reaction was carried out for 1 hour. After that, carbon black (Ketchenblack D J-60
47 g of 0.0° (manufactured by Lion Akzo Co., Ltd.) was added. Naori-Bon black was dried under reduced pressure at 200° C. for 1 hour and slurried with dehydrated hexane.

Thereafter, 2.0 mmol of triethylaluminum and 2.0 mmol of diethylaluminum chloride were added,
The temperature was raised to 90°C. The internal pressure of the system at this time is 1°5 kg.
/C111G. Next, hydrogen was supplied, and 2 kg/
Polymerization was carried out for 45 minutes while continuously supplying ethylene so as to maintain ci G, and a total amount of 469.3 g of a polyethylene composition containing ferrite and carbon black was obtained. The dried powder has a uniform black color, and according to an electron microscope, the ferrite surface is covered with a thin layer of polyethylene.
The carbon black was observed to be uniformly dispersed in the polyethylene.

In addition, when this composition was measured by TGA (thermal balance), the core material filling rate was 95.9wt%, and when calculated from the charged amount, the ratio of ferrite, polyethylene, and carbon blank was 24:1:0.025. It was a weight ratio. After that, it was placed in a hot air stream set at 120°C, and
．． Heat treatment was performed for 0 hours. The obtained career is 106
It was classified using a μm sieve to remove aggregates.

Production Example 1 was applied to 450 g of ferrite in the same manner as in Production Example 1 in an autoclave with an internal volume of 11 that had been replaced with argon.
The titanium-containing catalyst component prepared in (1) was added in an amount of 0.01 mmol as titanium atoms, and the reaction was carried out for 1 hour. Then, add carbon black (Ketchen black) from the upper nozzle of the autoclave.
EC, manufactured by Lion Akzo Co., Ltd.) 0.50 g was added. Naori-Bombrasov used a product that had been dried under reduced pressure at 200°C for 1 hour and made into a slurry with dehydrated hexane. Then 1.0 mmol of triethylaluminum, 1.0 mmol of diethylaluminum chloride.
0 mmol was added and the temperature was raised to 90°C. The system internal pressure at this time was 1.5 kg/cG. Next 1-
37.5 mmol (2.1 g) of butene was introduced, then hydrogen was supplied, the temperature was raised to 2 kg/cdG, and the total pressure was reduced to 5.
Polymerization was carried out for 28 minutes while continuously supplying ethylene to maintain kg/ctA G, and a total amount of 467 g of a polyethylene composition containing ferrite and carbon blank was obtained.

The dried powder had a uniform black color, and electron microscopy showed that the ferrite surface was thinly covered with polymer, and the carbon black was uniformly dispersed in the polymer. When this composition was measured by TGA (thermal balance), the weight ratio of ferrite, polymer, and carbon black was 27:1:0°03. Furthermore, when the polymer from which ferrite and carbon black were removed by Soxhlet extraction (solvent: xylene) was analyzed by IR, it was confirmed that it was a polyethylene copolymer containing 8 wt % of butene.

After that, it was placed in a hot air stream set at 120°C, and 2.5
Heat treatment was performed for a period of time. The obtained carrier is 106μm
It was classified using a sieve to remove aggregates.

K ■ A.1 Notice 4 200 parts by weight of ferrite fine powder with an average particle size of 0.2 μm and bisphenol type polyester resin (softening point = 12
3°C, glass transition point: 65°C, AV=21, OHV
: 43, Mn: 7600. Mw: 18840
0) 30 parts by weight were thoroughly mixed in a Henschel mixer (1,01) and kneaded in a twin-screw extrusion kneader. The resulting mixture was cooled, coarsely pulverized, finely pulverized with a hammer mill, and then coarse powder and fine powder were removed using an air classifier to obtain particles for forming a coating layer with a volume average particle diameter of 3.5 μm. .

A Henschel mixer (1
0ffi) and mixed for 2 minutes at 200 rpm.
The mixture was stirred to uniformly adhere the child particles around the carrier core material. Next, each particle was dispersed and supplied into a heated air stream (320°C), and instantaneous heating was performed for about 1 to 3 seconds to form a coating layer. To 100 parts by weight of the carrier having this coating layer, 2 parts by weight of a positive charge control agent (Gloson Hose EX (manufactured by Orient Kagaku Kogyo Co., Ltd.)) was fixed to the coating layer in the same manner. This carrier was immersed in 6N HCf for 2 hours, thoroughly washed with water, and vacuum dried at 60°C for 5 hours to obtain a resin-coated carrier having pores on the surface. The core material filling rate of the obtained carrier was 95.4 wt%.

Kiya! A'b Notice 5 Add 250 parts by weight of ferrite fine powder with an average particle size of 0.2 μm to a thermosetting silicone resin solution (KR-255: manufactured by Shin-Etsu Silicone Co., Ltd.) based on 100 parts by weight of the resin solid content, A coating liquid was prepared by thoroughly dispersing the mixture using ultrasonic waves. Sintered ferrite powder (F-200: manufactured by Powder Chick Co., Ltd., volume average particle diameter 70 μm) was used as the core material, and 25 wt% was applied to the core material using a spira coater (manufactured by Kaida Seiko Co., Ltd.).
Repeated applications were made to cover the area. Thereafter, the temperature in the system was raised to 150° C. to cure the resin, thereby obtaining a thermosetting silicone resin-coated carrier in which fine ferrite powder was dispersed. This carrier was immersed in 6N HCl for 2 hours, thoroughly washed with water, and vacuum dried at 60°C for 5 hours to obtain a resin-coated carrier having pores on the surface. The core material filling rate of the obtained carrier was 91.5 Wt%.

6 An acrylic resin solution with a solid ratio of 2% (Acridesk A405: manufactured by Dainippon Ink Co., Ltd.) was used as the coating liquid, and a sintered ferrite powder (F-200: manufactured by Powdertic Co., Ltd., volume The core material was coated with a spiracoater (manufactured by Kaida Seiko Co., Ltd.) using particles with an average particle size of 70 μm to provide a coating of 1.0 wt%.Then, the temperature in the system was raised to 150°C to coat the resin. was cured to obtain a thermosetting acrylic resin-coated carrier.

The core material filling rate of the obtained carrier was 99. It was Owt%.

1 g of each carrier obtained in Production Examples 1 to 5 and Production Example 6
Table 1 shows the total pore volume (ld/g) per coating layer, the total pore volume (mf/N1) per coating layer 11d, and the average pore diameter.

(This page, hereafter in the margin) Table 1 Figures 8 to 12 are diagrams showing the relationship between pore diameter and volume fraction. The volume fraction is the ratio of the pore volume within a certain pore diameter range to the total pore volume, expressed as a percentage.

In addition, the core material filling rate (wt%), true specific gravity (g/c&), and bulk specific gravity (g/c&) of the carriers obtained in Carrier Production Examples 1 to 6 are also shown.
crA), electrical resistance and specific surface area (H/g) are shown in Table 2 below.

Table 2 Note that the total pore volume and average pore diameter of the carrier are values calculated from the measurement results of the carrier pore distribution. The pore distribution of the carrier was determined by mercury porosimetry. The measurement was carried out using Poresizer 9310 (manufactured by Takasugi Seisakusho Co., Ltd.) at a mercury contact angle of 130° and a surface tension of 484 dyn/cm. The results are shown in FIGS. 7 to 12.

FIG. 7 is a diagram showing the relationship between pore diameter and infiltration volume. The infiltration volume represents the pore volume into which mercury was injected up to the maximum pressure at the time of measurement.

*6N Value after Hcl immersion In addition, specific gravity measurement is ・Electronic balance: Sensitivity 0.1 mg.

・Pycnometer: A pycnometer with a Gerussac thermometer specified in JIS R3501 (glassware for analytical chemistry), internal volume 50-0 ・Thermostatic water tank: A device that can maintain the water temperature at 23:=0.5°C.

The measurement was carried out using a measuring device equipped with the following procedure.

■ Accurately weigh the mass of the pre-dried vicinometer to the nearest 0.1 mg.

■ Fill the pycnometer with sufficiently degassed n-hebutane and keep it in a constant temperature water bath at 23±0.5°C for 1 hour.
Align the liquid surface accurately with the marked line. Take it out from the constant temperature water bath, completely wipe off the water from the outside, and then weigh its mass accurately to the digit of 0.1 square meters.

■ Next, after emptying the pycnometer, sample 10~
Collect 15g, weigh it again accurately to the digit of 0.1■,
Determine the mass of the sample by subtracting the results.

(2) Gently add 20 to 30 mfl of degassed N-heptane to the pycnometer containing the sample to completely cover the sample, and then gently remove air from the liquid in a vacuum desiccator.

■Next, the N
- Filled with hebutane and placed in a constant temperature water bath at 23 ± 0.5 °C.
Hold time. After accurately aligning the liquid surface with the marked line, take it out, wipe off the water on the outside, and reduce the mass to 0.1.
Weigh accurately to the digit marked ■.

■ The specific gravity is calculated using the following formula.

S=a-d/(b-c+a) Here, S: specific gravity a: Mass of sample (g) b: Fill the immersion liquid up to the marked line of the pycnometer. Mass when inserted (g) C: Marked line of the vicinometer containing the sample Mass when filled with immersion liquid up to (g) d: Specific gravity of immersion liquid at 23°C The bulk specific gravity was based on JIS 22504.

The electrical resistance is measured by using a metal circular electrode with a thickness of 1 inch and a diameter of 50 mm.
Place the sample so that the mass is 895゜4g and the diameter is 2.
A guard electrode of 0III11 with an inner diameter of 38 mm and an outer diameter of 42 mm was mounted, and the current value after 1 minute when a DC voltage of 500 V was applied was read and converted to the volume resistivity ρ of the sample. The measurement environment was a temperature of 25±1° C. and a relative humidity of 55±5%. Measurements were repeated five times and the average was taken.

The specific surface area was measured by the BET method using nitrogen gas adsorption. The device used was Flowsorb 2300 (manufactured by Takasugi Seisakusho Co., Ltd.).

Next, an example of the toner 25 used in the method of the present invention will be described along with an example of its production.

Ingredients Parts by weight: Polyester resin 100 (softening point: 130°C;
Glass transition point: 60"C, AV25.0HV38) ・Carbon blank 5 (manufactured by Mitsubishi Kasei Co., Ltd., MA #8) ・Dye 3 (manufactured by Odogaya Chemical Co., Ltd., Spiron Black TRH) Thoroughly mix the above materials in a whole mill. After that, the mixture was kneaded on three rolls heated to 140° C. After cooling, the kneaded product was coarsely ground using a feather mill, and then finely ground using a jet mill.

After that, air classification was performed to obtain a volume average particle size of 8.1 μm, and 0.3 wt% of hydrophobic silica (manufactured by Nippon Anilosil Co., Ltd., R974) was added to the toner, and the toner was mixed using a Henschel mixer. Obtained.

2 consisting of the above toner and the carrier 21 of Production Example 2.
Component developer, the toner and carrier 26 of Production Example 6
(Comparative Conventional Example) When the toner charge rise property was evaluated, as shown in FIG. 13, when the carrier 21 of Production Example 2 was used (O mark)
In this case, the toner charge rise property was superior to that in the case where carrier 26 of Production Example 6 was used (Δ mark). Manufacturing example 1
．． When carriers Nos. 3 to 5 were used, similar to the carrier of Production Example 2, excellent charge rise properties were exhibited.

Note that the toner charge rise property was evaluated as follows.

(Evaluation method) Literature (Journal of Electrophotography Society, Vol. 27, No. 3 (1988)
Using a developer prepared at a toner mixing ratio of 2 wt % by the method described in "Determination of Developer Charging Speed"), the toner charge amount q at developer mixing time t was measured.

(Results) The relationship between log (qm-q) and mixing time t is shown in FIG. Here, 91 indicates the saturation (or maximum) charge amount.

l og (qm-q) exhibits linearity with respect to time, and its slope indicates the magnitude of the charging rise rate.

The developing device IA was installed in an electrophotographic printer having a 400 dpi digital image forming system equipped with an organic photoreceptor as an image carrier, and 20,000 sheets were printed using the following two-component developer under the following conditions. I did a running test.

(Conditions) Photoreceptor peripheral speed: 140 flrm/se
c Developing sleeve 5 Developing sleeve 5 rules Charging potential of photoreceptor surface: -630 V developing bias voltage knee 480 V DC voltage and 1500 VF-P, 2
000Hg O) Rotation speed of bias voltage mixing members 2 and 3 with superimposed AC voltage 7 1 3 0r. p. m.

(Developer) Carrier: Carrier of Production Example 2 and Production Example 6 (Comparative Example) Toner: Toner of the above Production Example These carriers and toners were combined to prepare two types of developers with an initial toner mixing ratio of 6 wt%.

Further, even during running, the toner mixing ratio is controlled to be approximately 6 wt%.

The results obtained are shown in the table below.

As can be seen from this result, according to the method example of the present invention described above, the developing device IA can be made smaller and more compact by using the screw-type mixing and stirring members 2 and 3, and toner fogging and toner scattering of images do not occur. Furthermore, good results were obtained with no change in solid image density or 4 dot 1ine line width.

Next, the developing device IB shown in FIG.
A running test of 10,000 sheets was conducted.

The conditions and toner used were the same as in the test using apparatus IA.

Similar to the results of the above test using the device IA, there was no toner fog or toner scattering in the machine even in the running test of 20,000 sheets, and solid image density and 4 dot
Good results were obtained with no change in line width for 1 ine.

As described above, by using a screw type member for mixing and stirring the carrier and toner, the developing device can be made smaller and more compact, and by using a resin-coated carrier having pores on its surface, It has excellent mixing properties of carrier and toner, toner disintegration properties, and toner charging properties, and as a result, there is no toner scattering.
It has become possible to stably obtain good images with less.

〔Effect of the invention〕

As explained above, according to the present invention, there is provided an electrophotographic developing method for developing an electrostatic latent image on an image carrier using a two-component developer consisting of a magnetic carrier and a toner. In addition, it is possible to provide a developing method that has good mixing properties between the carrier and toner, has a good toner charging start-up, and is less likely to cause problems such as toner fog and toner scattering.

[Brief explanation of drawings]

1 and 2 are a plan sectional view and a sectional view perpendicular to the width direction of the developing device for carrying out the method of the present invention;
FIG. 3 is a cross-sectional view of another example of a developing device for carrying out the method of the present invention, FIGS. 4 and 5 are schematic cross-sectional views of a resin-coated carrier used in the method of the present invention, and FIG. 6 is a conventional resin-coated carrier. A schematic cross-sectional view of the coated carrier, FIG. 7 is a graph showing the relationship between the pore diameter of the carrier surface pores and the infiltration volume, and FIGS. 8 to 12 C...Photosensitive drum...Magnetic carrier 3... Resin coating layer 5...Toner 22...Core material 24...Pore 26...Conventional carrier

Claims (1)

[Claims] (1) In an electrophotographic development method in which an electrostatic latent image on an image bearing member is developed using a two-component developer consisting of a magnetic carrier and a toner, the carrier and toner are mixed and stirred using a screw-type mixing and stirring member. An electrophotographic developing method characterized in that the carrier is a resin-coated carrier having a large number of pores on its surface.