JPH0470883A - Electrostatic latent image developing method - Google Patents

Abstract

PURPOSE:To prevent toner scattering and toner fog by using resin coated carrier having pores on its surface in the case of developing an electrostatic latent image by holding developer on the outer periphery of a sleeve which moves around a fixed magnet body and bringing it into contact with a photosensitive body. CONSTITUTION:The developer supplied to a developing sleeve 6 is held by the magnetic force of the magnet body 7 and a fixed quantity of developer is carried to a developing area by a developer regulating member 8. The developer which reaches a pole N1 on an upstream side receives repulsive magnetic field by the adjacent same poles and force by the rotation, and a cascade developing occurs, thereby improving developing efficiency. However, in this magnetic brush developing method, the developer is severely stirred on the developing sleeve 6 near the same magnetic pole and the toner is easily scattered and spilt because of the cascade developing. Then, such a trouble is eliminated by using the carrier consisting of a carrier core material 1, a resin coating layer 2 with which the core material 1 is coated and the pores 3 formed on the surface of the layer 2.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a method for developing an electrostatic latent image using a magnetic brush.

Prior Art and Problems Various methods are known for developing electrostatic latent images, such as a powder cloud method, a cascade method, and a magnetic brush method. The present invention is classified into the magnetic brush development method.

The magnetic brush/development method uses magnetic force to attract a two-component developer consisting of a mixture of carrier and toner, forms the developer in the shape of a brush at the magnetic pole, and rubs the electrostatic latent image on the photoreceptor. However, in order to meet today's demands for high-speed copying, various improvements have been made to the magnetic brush development method. As one of the improvements, a method using the same magnetic poles has been disclosed (for example, Japanese Patent Publication No. 60-30946, Japanese Patent Publication No. 58
-43739, JP-A-49-24147, etc.).

However, in the same magnetic brush type magnetic brush development method, the developer is subjected to a strong stirring action near the same magnetic poles and between the same magnetic poles, and avalanche development of the developer occurs, so that toner scattering is likely to occur. Therefore, if the amount of charge of the toner supplied to the same magnetic pole portion is insufficient or uneven, the poorly charged toner will scatter, causing problems such as contamination inside the machine.

In addition, the poorly charged toner also has an adverse effect on the image, such as toner fog, resulting in a problem of deterioration of image quality.

Problems to be Solved by the Invention The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an electrostatic latent image developing method using the same magnetic pole method, which is free from problems such as toner scattering and toner fog. do.

Means for Solving the Problems The present invention holds a developer on the outer periphery of a developing sleeve that moves around a fixed magnet, and arranges magnetic poles of the same polarity next to each other on a portion of the fixed magnet facing the photoreceptor. The present invention relates to a method of developing an electrostatic latent image by bringing an agent into contact with a photoreceptor, in which a resin-coated carrier having a large number of pores on the surface is used as the carrier.

A specific example of the structure of the electrostatic latent image developing method of the present invention will be explained with reference to FIG. In the figure, (9) is a photoreceptor (P/C), and a developing sleeve (6) is placed on the left side with a certain gap therebetween. Inside the developing sleeve (6), a magnet (
7) are fixedly arranged.

The developing sleeve (6) is a cylindrical body made of a conductive non-magnetic material, on the surface of which micro recesses are formed by blasting, and the developing sleeve (6) is attached to a photoreceptor (P/
C) with a constant developing gap, and can be rotated clockwise (in the direction of arrow (b)). Further, a DC bias power source (not shown) is usually connected between the developing sleeve (6) and ground.

The magnet body (7) fixedly housed inside the developing sleeve (6) has a plurality of magnets extending in the axial direction.
The magnetic poles (N1, N2 poles) of the same polarity are arranged next to each other on the photoreceptor (P/C) facing portion. Reference numeral (8) denotes a developer regulating member, which is arranged with a certain gap from the developing sleeve (6).

In the above configuration, the developer supplied to the developing sleeve (6) is transferred to the developing sleeve (6) by the magnetic force of the magnet (7).
) and is conveyed over the developing sleeve (6) by rotation of the developing sleeve (6). A certain amount of the developer is conveyed toward the development area by passing through the regulation gap between the developer regulation member and the development sleeve (6).

The developer that is transported on the developing sleeve (6) and reaches the upstream polarization (Nl) is subjected to a force in the A direction from a repulsive magnetic field caused by adjacent same poles, as shown in FIG. at the same time,
In order to receive the force B that is being sent downward in the figure due to the rotation of the developing sleeve (6), when a certain amount of developer is filled on the upstream polarization (N1), it is held by the magnetic force of the upstream polarization. It can no longer hold back and begins to fall towards the downstream side m (N2).

In this way, by creating a homopolar configuration, upstream polarization (Nl
), the developer is more densely packed and exists in a disturbed state, and furthermore, in region C, it drips down toward the downstream polarization (N2) direction while maintaining the above disturbed state. , resulting in a so-called cascade state.

As for the configuration of the developing device of the present invention, it is sufficient that magnetic poles of the same polarity are arranged next to each other in the portion of the fixed magnet inside the developing sleeve facing the photoreceptor, and the contact state between the magnetic brush on the developing sleeve and the photoreceptor is are N1 and N2 as shown in Figure 4.
When both of the best magnetic brushes come into contact, as shown in Figure 5, when only the magnetic plan on the magnetic pole (Nl) located upstream with respect to the rotational direction of the developing sleeve comes into contact, as shown in Figure 6. Any case in which only the magnetic plan on the magnetic pole (N2) located on the downstream side contacts is acceptable.

When the magnetic brushes on the N1 and N2 poles contact each other (Fig. 4), the upstream polarization (N1
) is in contact (Figure 5), the downstream polarization (N
2) When only the upper magnetic bra is in contact, the development efficiency is improved in either case by cascade development and development at the uppermost position on the downstream side.

As mentioned above, in the same magnetic pole type magnetic brush development method, the developer is vigorously stirred on the developing sleeve (6) near the same magnetic pole, and cascade development occurs, resulting in toner scattering and toner spillage. is likely to occur. In particular, toner scattering and toner spillage are largely caused by the presence of poorly charged toner and agglomerated toner. The problems of toner scattering and toner spillage can be improved by using a carrier having a large number of pores on its surface, as will be described later, as the carrier constituting the developer.

The carrier will be explained in detail below.

The resin-coated carrier of the present invention includes a carrier core material (1), a resin coating layer (2) covering the carrier core material (1), and pores (3) formed on the surface of the resin coating layer.

Compared to the conventional resin-coated carrier shown in Figure 3, the pores (3
) is a major feature.

In this way, the presence of pores on the surface of the resin-coated carrier ensures sufficient contact between the toner particles (4) and the carrier particles even when used together with toner (even toner with a small particle size). The toner can be charged quickly, each toner particle can be sufficiently uniformly charged, and toner scattering due to charging failure can be prevented.

Furthermore, since the pores on the surface of the carrier are excellent in capturing toner particles, this is also effective in preventing toner scattering.

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

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

Each pore size present on the surface of the resin coating layer is 0.001 to 3 μm
, preferably 0.001 to 2 μm, more preferably 0.001 to 2 μm.
It is desirable that the thickness be distributed in the range of 0.005 to 2 μm.

If the pore size is smaller than 0.001p11, sufficient effects cannot be expected from the viewpoint of toner crushability, etc.
If it is larger than m, the toner trapping property will be too strong,
Fluidity and developability may be impaired.

The average pore diameter corresponds to the pore diameter distribution range mentioned above.
It is desirable that the thickness be in the range of 0.1 to 0.5 μm1. By setting the average pore diameter within the above range, the crushability of the toner and the charging characteristics of the toner can be improved.

In the present invention, the total pore volume is expressed in two ways: total pore volume per carrier Ig (mMg) and total pore volume per 1 mQ of coated resin layer (mL'm(1)).

The total pore volume (ml/g) per carrier Ig can be determined by mercury poronmetry. In the carrier of the present invention, the value is 0.001 to 0゜l mQ/
g, preferably 0.01-0.05+nQ/g. If the value is less than 0.001 m (1/g), there are insufficient pores on the carrier surface, and there is a risk that the effect of the pores will not be obtained.O,1
If it is larger than m12/g, there will be too many pores and the coating layer will become brittle.

The total pore volume (+nQ/+++Q) per coating resin 11 is the total pore volume per 1 g of carrier (+o(2/
g) can be determined by converting from the true specific gravity of the coating layer and the carrier core material filling rate. In the carrier of the present invention, the value is 0.1 to 2 mQ/ll112
, preferably a value of 0.5 to 1.5 mQ/IIIQ. Its value is O, l mQ/m
If it is smaller than Q, there will be insufficient pores present on the carrier surface, and there is a possibility that the effect of the pores will not be obtained. 2
When it is larger than IIIQ/mQ, there are too many pores and the coating layer becomes brittle.

Next, the constituent materials of the carrier of the present invention will be explained.

The carrier core material, which is a component of the carrier of the present invention, has a size of at least 20 μm (average particle diameter) in order to prevent carrier adhesion (scattering) to the electrostatic latent image bearing member. In order to prevent deterioration of image quality such as the occurrence of streaks, etc., a thickness of at most 100 μm is used. 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, chromium nitride,
Nitrides such as vanadium nitride, mixtures with carbides such as silicon carbide and tungsten carbide, ferromagnetic ferrite, and mixtures thereof can be used.

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 and mixtures thereof, such as urethane/urea resins, resins, polyethylene resins, and thermosetting resins, as well as copolymers and block polymers of these resins. Graft polymers, polymer blends, etc. 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 a carrier is a toner with a small particle size, the smaller the particle size of the toner, the smaller the toner's heat capacity and the more likely it is to become spent. From this point of view, coating resins with good mold releasability, such as linicone resins or polyolefin resins, are preferred. The surface of the carrier of the present invention is made up of a carrier coating resin of 70% or more, preferably 90% or more,
It is more preferable to cover 95% or more. If the coverage is less than 70%, the characteristics of the carrier core material itself (unstable environmental resistance, decreased electrical resistance, unstable charging) will be strongly visible through the background, making it impossible to take advantage of the advantages of the resin coating.

The filling rate of the carrier core material is set to about 90 W[% or more, preferably 95 Vt% or more. The filling rate may be interpreted as indirectly regulating the thickness of the resin coating layer of the carrier, and as the carrier core material filling rate becomes smaller than 9Qvt%, the coating layer becomes too thick and the developer I actually becomes thinner. Even if applied, the durability and charge stability required for the developer are not satisfied due to peeling of the coating layer, increase in the amount of charge, etc., and the image quality is poor in fine line reproducibility and image density is reduced. Problems such as

It is also possible to express the resin coating layer thickness indirectly by specific gravity. The specific gravity of the carrier of the present invention is greatly influenced by the type of carrier core material, but as long as the above carrier core material is used, the specific gravity of the carrier of the present invention is preferably 3.5 to 7.5, preferably 4.0 to 6.01. It shows a value within the range of 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 of the present invention is 1×to'-
IXIO1'Ω" cm, preferably 10'-1013
It is preferably set to about 10'-10'Ω'cm rather than 0'CL. If the electrical resistance is less than 1X10'Ωcm, carrier development occurs and the image quality deteriorates.

On the other hand, if it is larger than 1 x 101' 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 used in the present invention is further provided with unevenness of the resin coating layer. Figure 2 shows the resin coating layer (2
) shows an uneven form, and the pores (3) are present on the uneven surface of the resin coating layer (2). By imparting such irregularities to the surface of the carrier, it is possible to obtain a carrier with improved toner charge rise characteristics, toner scattering, toner agglomeration and disintegration properties, and the like.

Surface unevenness will be explained in more detail.

The surface unevenness structure of the surface coating layer is expressed by the following formula [11°] where the outer circumference represents the outer circumference of the projected image of the carrier particles, and the area represents the average value of the projected area of the carrier particles. ] is expressed by the shape factor S. Preferably, the value is within the range of 130-200.

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 is. For example, it can be measured using an image analyzer (Luzex 50J) 0; 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, so it must be measured with the above model in particular. It does not mean that.

Furthermore, additives such as fine particles having a charge imparting function or conductive fine particles may be added to the carrier-coated resin layer of the present invention.

Fine particles with a charge imparting function include CrO2, Fe2
0x, Fe3O4% I ro,, M n O2, M
oO2, NbO2, PtO,, Tie! , Ti201,
Ti, O,, WO2, V2O3, Al2O3, MgO,
Specific examples include metal oxides such as 5i02, ZrO, and BaO, and dyes such as Nigron base and Spiro black TRH.

Examples of conductive fine particles include carbon black, carbon black such as acetylene blank, and SiC.

Carbide such as TiC, MoC1ZrC, BNlNbN.

Examples include nitrides such as TiN and ZrN, and 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 blank is effective in improving developability and obtaining images with high image density and clear contrast. It is thought that this is because the addition of conductive fine particles such as carbon black lowers the electrical resistance of the carrier appropriately, and the leakage and accumulation of charges are performed 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 the resin-coated carrier of the present invention, magnetic powder is added to the resin coating layer. As a result, a carrier with excellent gradation reproducibility can be obtained. This is thought to be because the addition of magnetic powder to the resin coating layer resulted in a surface composition similar to that of the binder-type carrier, and the chargeability and specific gravity approached those of the binder-type carrier.

The addition of borides and metal carbides has some effect on the rise of charging.

The size, amount, etc. of the above-mentioned additives are determined by the pore morphology, coverage rate,
There are no particular limitations on the size of the fine particles as long as they satisfy various properties such as electrical resistance, but in relation to the preferred method of manufacturing the carrier of the present invention described later, the size of the fine particles may be determined by aggregation in a resin solution or dehydrated hexane, for example. Any particle diameter is sufficient as long as it can be uniformly dispersed to form a slurry without causing any damage, and specifically, the volume average particle diameter is 2 to 0.001. c+a, preferably 1-0. It is sufficient that the thickness is about 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 0.1 vt% to 5 Qwt%, preferably 1 Qwt% based on the coating resin.
．． Ovt% to 40wt% is suitable.

In particular, when using the present invention with a filling rate set in the range of 90 to 97 wt%, it is preferable to add additives such as fine particles with a charge imparting function or conductive fine particles to the resin coating layer. When the filling rate of the carrier is as small 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 problem arises in that the reproducibility decreases. The problem is solved by the addition of the above additives.

Next, a method for producing a resin-coated carrier having pores according to the present invention will be explained. The method for producing the carrier of the present invention is not particularly limited as long as the carrier having the above-mentioned pores can be obtained, and 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 dry 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, there is a method in which ferrite is eluted by immersing a carrier having a resin coating layer containing ferrite in an acidic aqueous solution such as hydrochloric acid. can be formed.

Furthermore, when adding fine particles or conductive fine particles having a charge imparting function as described above, it is sufficient to add these additives and make them exist in the coating resin solution, or to form pores such as ferrite. 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 preferred method for producing the carrier of the present invention is a surface polymerization coating method.

The surface polymerization coating method uses: ■ a highly active catalyst component that contains titanium and/or zirconium and is soluble in a hydrocarbon solvent; 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 above-mentioned coating layer. Specifically, JP-A-60-106
The method described in Japanese Patent No. 808 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.

Toners used in combination with the above carriers include:
The colorant and/or charge-imparting agent is not particularly limited, and the colorant and/or charge-imparting agent is added to the pulverization method toner or seven toner obtained by mixing and agitating the thermoplastic resin, colorant, and/or charge-imparting agent, and then crushing and classifying the mixture. A wall material with a higher softening point ( A capsule toner wrapped in a capsule shell (capsule shell) or a photoconductive toner whose surface is coated with a photoconductive substance, and has an average particle size of about 3 to 20 μm, is used.

Further, a fluidizing agent may be added to the toner of the present invention.

As the fluidizing agent, silica, aluminum oxide, titanium oxide, silica, an aluminum oxide mixture, a silica/titanium oxide mixture, etc. are used. In particular, a mixture of silica and titanium oxide is more preferable, and the ratio of silica and titanium oxide is 0.1 to 0.3% by weight of silica/titanium oxide, 10.1 to 1% by weight, and 0.1 to 2% by weight is added to the toner. It is preferable to do so. The fluidizing agent may be subjected to hydrophobic treatment using a coupling agent or a surfactant. In the present invention, the carrier and toner obtained as described above are mixed to form a developer.

The developer obtained in this manner is excellent in toner charge build-up properties, toner scattering prevention, toner agglomeration disintegration properties, and the like.

The mixing ratio of toner and carrier is 2 to 20% by weight of toner.
, preferably 3 to 15% by weight, more preferably 4 to 12% by weight
Weight%. If the toner mixing ratio is less than 2% by weight, the amount of toner charge will increase and sufficient image density will not be obtained; if it is more than 20% by weight, the copy area will be contaminated due to toner scattering, or the image will be Toner fog occurs.

The present invention will be explained below using examples.

(+) Toner production example Ingredients Part by weight Styrene-n-butyl methacrylate resin 100 (softening point, 1
32°C; Glass transition point, 60'C1) Carbon black 5 (manufactured by Mitsubishi Chemical Corporation, MA#
8) - Dye 5 (manufactured by Orient Kagaku Kogyo Co., Ltd., Bontron P-51) The above materials were thoroughly mixed in a ball mill, and then kneaded on three rolls heated to 140°C. After the kneaded material was left to cool, it was coarsely ground using a feather mill and further finely ground using a jet mill.

After that, air classification was performed to obtain a volume average particle size of 7.8 μm,
Hydrophobic silica (manufactured by Nippon Aerosil Co., Ltd., R974) was added to the toner in an amount of 3 wt % and mixed using a Hennonel mixer to obtain a toner.

Carrier Production Example 1 (1) Preparation of titanium-containing catalyst component Into an argon-substituted flask with an internal volume of 500+nQ, 200 mQ of dehydrated dohebutane was added at room temperature and 120°C in advance.
Add 15 g (25 mmol) of stearic acid magne and rum dehydrated under reduced pressure (2 mmHg) to form a slurry. After 0.44 g (2.3 mmol) of titanium tetrachloride was added dropwise with stirring, the temperature was increased and the reaction was carried out for 1 hour under reflux to obtain a viscous and transparent solution of the titanium-containing catalyst component.

(2) Activity evaluation of titanium-containing catalyst component In an argon-substituted autoclave with an internal volume of IQ, 400 mQ of dehydrated hexane, 0.8 mmol of triethylaluminum, 0.8 mmol of diethylaluminium chloride, and the titanium-containing catalyst component obtained in (1) above. Collect 0.004 E mol as a titanium atom and add it to 90
Do not raise the temperature to °C. This height, system internal pressure l, 5 kg
/cm2G. Then, hydrogen is supplied and 5.5
After increasing the pressure to kg/cm”G, the total pressure is 9,5
Ethylene was continuously supplied so as to be maintained at kg/cm'G, and polymerization was carried out for 1 hour to obtain 70 g of polymer. Polymerization activity is 365 kg/g・T1・Hr,
MFR of the obtained polymer (190°C1 load 2.16
Melt flowability in kg, JIS K7210) is 4
0 and l=.

(3) Reaction of titanium-containing catalyst component and filler and polymerization of ethylene Sintered ferrite powder F- dried in 500 mQ of dehydrated hexane at room temperature and under reduced pressure (2 mmHg) at 200°C for 3 hours in an argon-substituted autoclave with an internal volume of 1i2 20
0 (manufactured by Powder Chick, volume average particle diameter 70 μm) 45
0g was added and stirring was started. Next, the temperature was raised to 40°C, and 0.02 mmol of the titanium-containing polymerization catalyst component (1) was added as titanium atoms, and the reaction was carried out for about 1 hour. Then, 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/
It was cI112G. Next, hydrogen was supplied, and 2 kg/
After increasing the pressure to 6 kg/cm2G, polymerization was carried out for 40 minutes while continuously supplying ethylene to maintain the total pressure at 6 kg/cm2G, to obtain a total amount of 473 g of a ferrite-containing polyethylene composition. It has a grayish-white color,
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.

Carrier Production Example 2 In an argon-substituted autoclave with an internal volume of IQ, the same procedure as in Production Example 1 (3) was carried out, and 450 g of ferrite was prepared in Production Example 1 (1)! 0.02 mmol of titanium as a catalyst component was added, and the reaction was carried out for 1 hour. After that, spray black D from the upper nozzle of the autoclave.
J-600, manufactured by Lion Akzo Co., Ltd.) 047 g was charged. The Naori-Pon flask used was one that had been dried under reduced pressure at 200°C for 1 hour and made into a slurry with dehydrated hexane. Thereafter, mol of triethylaluminum and 2.0 mmol of diethylaluminium chloride were added, and the temperature was raised to 90°C. At this time, the system internal pressure was f-1,1,5 kg/Cm''G.

Next, hydrogen was supplied and the pressure was increased to 2 kg/Cm2G, and then ethylene was continuously supplied so as to maintain the total pressure at 6 kg/cm2, and polymerization was carried out for 45 minutes until the total amount was 469.
．． 3 g of a polyethylene composition containing ferrite and carbon black was obtained. The dried powder had a uniform black color, and electron microscopy revealed that the ferrite surface was thinly covered with polyethylene, and the carbon black was uniformly dispersed in the polyethylene. In addition, when this composition was measured by TGA (thermal balance), the core material filling rate was 95.9vt%.

Calculating from the amount charged, the weight ratio of ferrite, polyethylene, and carbon brane was 24:1:0.025. After that, it was placed in a hot air stream set at 120°C, and 2.
Heat treatment was performed for 0 hours. The obtained carrier is 106μ
The mixture was classified using a No. m sieve to remove aggregates.

Carrier Production Example 3 In the same manner as in Carrier Production Example 1, the titanium-containing catalyst component prepared in (1) of Production Example 1 was added to 450 g of ferrite in an argon-substituted autoclave with an internal volume of IQ. 01 mmol was added and the reaction was carried out for 1 hour. Then, add carbon black (Ketchen black) from the upper nozzle of the autoclave.
black) E C% Manufactured by Lion Akzo Co., Ltd.)
0.50g was added. Naori-pon blank is 20
The sample was dried under reduced pressure at 0°C for 1 hour and made into a slurry with dehydrated hexane. Thereafter, 10 mmol of triethylaluminum and 1.0 mmol of diethylaluminum chloride were added, and the temperature was raised to 90°C. At this time, the system internal pressure was 1.5 kg/cm"
It was G. Next, 37.5 mmol of 1-butene (2,1
g) was introduced, then hydrogen was supplied to increase the pressure to 2 kg/cm2G, and polymerization was carried out for 28 minutes while continuously supplying ethylene to maintain the total pressure at 6 kg/cm2G, resulting in a total amount of 467 g of ferrite and A carbon black dowel polyethylene composition 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 ratio of ferrite, polymer, and carbon blank was 27:l:0.03.
The weight ratio was Furthermore, when the polymer from which ferrite and BJ-Ponne rank were removed by Soxhlet extraction (solvent, quinolene) was analyzed by IR, it was found to be 3vt%.
It was confirmed that it is a polyethylene copolymer containing butene.

After that, it was placed in a hot air stream set at +20°C, and 2.5
Heat treatment was performed for a period of time. Obtained j; carrier 106μ
Classify with a sieve and remove aggregates.

Carrier Production Example 4 250 parts by weight of ferrite fine powder with a volume average particle diameter of 0.2 μm and 30 parts by weight of styrene-acrylic resin (38M73F: manufactured by Sanyo Chemical Co., Ltd.) were mixed in a Henschel mixer (104).
Mix well and knead using a twin-screw 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 size of 2.0μ width. Ta.

Carrier core material (sintered ferrite powder F-200: manufactured by Powder Tech, volume average particle size 70 μm) to.

Parts by weight and 30 parts by weight of the child particles were supplied to a Henschel mixer (10ff) and mixed and stirred at 200 rpm for 2 minutes to uniformly adhere the child particles around the carrier core material. Next, each particle was dispersed and supplied into a heated air stream (320c), 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 negative chargeability control agent (Bontron 5-34, manufactured by Orient Chemical Industry Co., Ltd.) was fixed to the coating layer in the same manner. This carrier was immersed in 6N HCQ 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.

Carrier Production Example 5 250 parts by weight of ferrite fine powder with a volume average particle diameter of 02 μm was added to a thermosetting silicone resin solution (KR-255, manufactured by Shin-Etsu Silicone Co., Ltd.) based on 100 parts by weight of the above resin solid content, and the mixture was subjected to ultrasonic waves. The coating liquid was prepared by thoroughly dispersing the liquid. Using sintered ferrite powder (F-200, manufactured by Powder Chick Co., Ltd., volume average particle size 70 μm) as the core material, the core material was
Repeated applications were made to achieve wt% coverage. Thereafter, the temperature in the system was raised to 150° C. to cure the resin, thereby obtaining a carrier coated with a thermosetting resin-cone resin in which fine ferrite powder was dispersed. This carrier was immersed in 6N HCQ 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.

Carrier Production Example 6 A carrier was produced in the same manner as in Carrier Production Example 5, except that ferrite fine powder was not added and acid treatment was not performed.

Total pore volume per gram of carrier (mL'g), total pore volume per 1 mQ of coating layer CmQ/mQ), average pore diameter (μm), core material obtained in Kishichiria Production Examples 1 to 6 Filling rate(
wt%), true specific gravity (g/cm'), electrical ratio, t (g/cm
The electrical resistance and specific surface area (m"/g) are shown in Table 1.

(Hereinafter, blank space) 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 borosimetry. The measurement was carried out using Boasizer 9310 (manufactured by Kofu Seisakusho Co., Ltd.), and the contact angle of mercury was 130', and the surface tension was 484 dyn/am. The results are shown in FIGS. 8 to 13.

FIG. 8 is a diagram showing the relationship between pore diameter and intrusion volume. The intrusion volume represents the pore volume into which mercury is injected up to the maximum pressure at the time of measurement.

FIGS. 9 to 13 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.

Specific gravity measurement ・Electronic balance: Sensitivity 0, 1111g.

・Pycnometer: A pycnometer with a Gerusanok thermometer specified in JIS R3501 (glassware for analytical chemistry), internal volume 50 m 12° ・Thermostatic water tank: Capable of maintaining water temperature at 23 ± 0.5° CI.

Measure using a measuring device equipped with
two.

■The mass of the pre-dried vicinometer is 0, l mg.
Weigh accurately.

■Fill the pi-2 meter with sufficiently degassed n-hebutane,
After keeping it in a constant temperature water bath at 05°C for 1 hour, adjust the liquid surface exactly to the marked line. Take it out of the constant temperature water bath, wipe off the water from the outside, and reduce its mass to 0.1 mg.
Weigh accurately to the nearest digit.

■Next, try Il+lO while emptying the vicinometer.
~15g is sampled, weighed again accurately to the 0 and 1 mg digits, and the mass of the sample is determined by subtracting the result in (■).

■ Gently add 20~30IIIQ of degassed n-hebutane to the vicinometer containing the sample to completely cover the sample, and then gently evacuate the air in the liquid in a vacuum tensometer.

0 Next, the pycnometer was degassed to the vicinity of the marked line.
Fill with hebutane and keep in a constant temperature water bath at 23±0.5°C for 1 hour. After accurately aligning the surface of the liquid with the marked line, take it out, wipe off the water from the outside, and reduce its mass to 0 or 1.
Weigh accurately to the milligram.

■Specific gravity is calculated using the following formula.

S = a-d/(b-c+a) Here, S: Specific gravity a: Mass of the sample (g) b: Mass when the immersion liquid is filled up to the marked line of the vicinometer (g) C: Vicinometer containing the sample Mass (g) when filled with immersion liquid up to the marked line d: The specific gravity of the immersion liquid at 23°C is in accordance with JIS Z2504.

The electrical resistance is measured by using a metallic circular electrode with a thickness of 1 IOm.

Place the sample so that the diameter is 50 mm, and the mass is 895°4.
g, 20mm diameter electrode, inner diameter 38mm, outer diameter 42II
A guard electrode of 1 m length was placed on the sample, and the current value after 1 minute when a DC voltage of 50 QV was applied was read and converted into the volume resistivity P of the sample. The measurement environment was a temperature of 25±1'c and a relative humidity of 55±5.
%, the measurement was repeated 5 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 Kofu Seisakusho Co., Ltd.).

Evaluation of charging rise property A toner mixing ratio of 2vt% was obtained from the carriers of Production Example 2 and Production Example 6 (-Comparative Example) and the toner obtained in the above Production Example.
Using the method described in "Determination of developer charging speed", Journal of the Society of Electrophotography, Vol. 27, No. 3 (1988), using a developer prepared in Measure (q) and t;.

Based on the measurement data, the relationship between log (qm - q) and L is shown in FIG. 14. Here, qm indicates the saturation (or maximum) charge amount.

Log(qm-q) shows linearity with respect to time L1, and its slope can represent the magnitude of the charging rise speed. , the steeper the slope of the straight line, the faster the charge rises.

The carrier of Production Example 2 exhibits superior charging rise characteristics compared to the carrier of Production Example 6 (=comparative example).

The carriers of Production Examples 1, 3, 4, and 5 also showed excellent charging rise properties as in Production Example 2.

Evaluation using the developing device (device configuration and conditions) Production Example 2 and Production Example 6 using the developing device with the configuration shown in Figure 4.
Using the carrier (=comparative example), a 50,000 sheet tear resistance evaluation was conducted under the following conditions.

The toner prepared in the above-mentioned production example was used as a developer, and the toner was made into a developer so that the initial toner mixing ratio was 5vt%, and the toner mixing ratio was controlled to 61% even during the durability period.

(Conditions)・Development gear knob・0.6mm・Regulation gap: 0, 4 inches・Photoconductor circumferential speed + 35
0 mm/sec・Developing sleeve circumferential speed/photoconductor circumferential speed −2,0・Angle between magnetic poles N1 and N2: 3 Qa・Strength of magnetic poles N1 and N2: 1000 Gauss・Developing bias −130V (Note that as the photoconductor (uses a photoreceptor) mode
0 to 10,000 sheets Original B/W ratio lO% 1 to 30,000 sheets Original B/
W ratio 15% 30,000 to 50,000 sheets Original B/W ratio 35% When using the carrier of Production Example 2, almost no toner scattering occurred during the printing durability evaluation of 50,000 sheets, and the initial image quality was It was able to be maintained and was in very good condition.

On the other hand, when using the carrier of Manufacturing Example 6 (comparative example), as the number of copies increases, the B/W of the original increases.
As an image with a high ratio is copied, toner scattering increases, and after 30,000 copies are made when the copy mode is entered with an original B/W ratio of 35%, the inside of the copying machine becomes more contaminated and toner fog occurs, which deteriorates the image quality. or decreased significantly.

Effects of the Invention A developer is held on the outer periphery of a developing sleeve that moves around a fixed magnet, and magnetic poles of the same polarity are arranged next to each other in a portion of the fixed magnet facing the photoreceptor, and the developer is brought into contact with the photoreceptor. By using a resin-coated carrier having a large number of pores on the surface as the carrier in the method of producing an electrostatic latent image, it was possible to prevent toner scattering and [-ner fog].

[Brief explanation of drawings]

1 and 2 are schematic cross-sectional views of the resin-coated carrier of the present invention. FIG. 3 is a schematic cross-sectional view of a conventional resin-coated carrier. 4 to 6 are diagrams for explaining embodiments of the electrostatic latent image developing method of the present invention. FIG. 7 is a diagram illustrating the behavior of the developer on the developing sleeve in the vicinity of the same magnetic pole. FIG. 8 is a diagram showing the relationship between the pore diameter of the carrier surface pores and the intrusion volume. FIGS. 9 to 13 are diagrams showing the relationship between the pore diameter and volume fraction of carrier surface pores obtained in each carrier production example. FIG. 1.1 shows the relationship between the developer mixing time and the rise of 1.sup. measure the obi

Claims (1)

[Claims] 1. A developer is held on the outer periphery of a developing sleeve that moves around a fixed magnet, and magnetic poles of the same polarity are placed next to each other on the photoconductor facing portion of the stationary magnet, and the developer is brought into contact with the photoconductor. A method for developing an electrostatic latent image, the method comprising using a resin-coated carrier having a large number of pores on its surface as the carrier.