JPH0470859A - Electrostatic latent image developing method - Google Patents

Abstract

PURPOSE:To enhance rising performance in the case of electrostatically charging toner and to prevent toner scattering, toner spill and toner fog by using developer in which carrier having many pores on its surface is combined. CONSTITUTION:The developer is supplied to a supply part A by a bucket roller 13 and carried on a developer carrying guiding member 12 in a direction (c) based on the rotation of a magnet body 11 in a direction (b) while the bristle height is regulated by a bristle height regulating plate 14. Next, the developer comes in contact with the surface of a photosensitive body 16 at the edge of the member 12 so as to develop an electrostatic latent image. At the same time, the developer comes in contact with the outer peripheral surface of a developer carrier 10 and is carried in the direction (b) between the carrier 10 and the member 12 by following the rotation of the carrier 10, then it is scraped off by a scraper 15 and returned to a developing tank. Then, the resin coated carrier constituted 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 is used.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for developing an electrostatic latent image using a magnetic brush used in electrophotographic copying processes and the like.

Conventional technology Conventionally, as a method for developing an electrostatic latent image using a magnetic brush, a developing material is transferred to a photoconductor by rotating a developing electrode (for example, a developer carrier that functions as a developing electrode) and one or both of a magnet body built therein. On the other hand, a method of transporting in one direction and developing is well known and commonly used.

For this type of development method, in order to avoid scraping of the toner image by the magnetic brush, prevent cast of the toner image, and improve image quality such as fine line reproducibility, there is a method in which the developing electrode is attached to the electrostatic latent image carrier. A developing method has been proposed in which the developer terminates contact with the surface of the electrostatic latent image carrier at a position approaching or closest to the surface (
For example, Japanese Patent Laid-Open No. 62-113162, etc.).

However, in such a developing method, the flow direction of the developer is forcibly changed at the position where the developer ends contact with the surface of the electrostatic latent image carrier.
The developer is subjected to a strong force and a stirring action. Therefore,
If the amount of charge of the toner supplied to the development area is poor or uneven, the toner with a low amount of charge will scatter at the above-described contact end position of the developer, resulting in toner fog and contamination within the apparatus. Therefore, it is necessary to uniformly charge the toner to an appropriate level and supply it to the development area.
If the carrier used has insufficient charging build-up characteristics due to frictional charging, the toner will not be charged to an appropriate level within the time it takes to reach the development area, resulting in toner scattering,
This causes problems such as toner fog and deterioration of image quality.

Additionally, the developer may cause agglomeration of toner particles, but the agglomerated toner is not sufficiently charged and, even when it reaches the development area, is not properly developed into an electrostatic latent image, resulting in a reduction in the quality of the copied image. Further, there is a problem in that the aggregated toner is not transported normally in the developer/direction changing area and falls out of the normal flow of the developer. The smaller the toner particle size, the more
Toner aggregation is likely to occur, and the above-mentioned problems are likely to occur.

Furthermore, when copying an image with a high black-and-white ratio (CB/W), or when copying is carried out under harsh conditions such as high temperature and high humidity, the toner's charge build-up becomes even worse. As a result, problems such as toner scattering and fogging become more noticeable.

Problems to be Solved by the Invention The present invention has been made in view of the above circumstances. A developing electrode for developing an electrostatic latent image is configured to terminate contact between the developer and the surface of the electrostatic latent image carrier at a position where the developing electrode is approaching or closest to the surface of the electrostatic latent image carrier. The developed electrostatic latent image developing method does not cause problems such as toner scattering, toner spillage, and toner fog, and is equally good when copying images with a high B/W ratio or under high temperature and high humidity conditions. A developing method capable of forming an image is provided.

Means for Solving the Problems #ta A development electrode is disposed opposite to the image carrier and is used to convey a developer and develop an electrostatic latent image formed on the surface of the electrostatic latent image carrier. In an electrostatic latent image developing method in which the developer terminates contact with the surface of the electrostatic latent image carrier at a position approaching or closest to the surface of the latent image carrier, #I formation of the developer is performed. The present invention relates to an electrostatic latent image developing method characterized in that a resin-coated carrier having a large number of pores on the surface is used as the carrier.

First, a case will be described in which the electrostatic latent image developing method according to the present invention is carried out by rotating the developer carrier and the magnet in the same direction.

In the electrostatic latent image developing method according to the present invention, a developing electrode (for example, a developer carrier that also functions as a developing electrode) is connected to an electrostatic latent image carrier (for example, a photoreceptor having a photosensitive layer on the surface). The developer terminates contact with the photoreceptor at the approaching or closest position (this contact area is referred to as the development area).

In the above-mentioned method, this type of development method is based on the developer conveyance speed (Vsl) by the developer carrier in the development area.
Specifically, if the developer conveyance speed (Vmg) by the magnet is made larger than the developer conveyance speed (Vmg), and the developer is not present on the outer circumferential surface of the developer carrier downstream of the development area, it is possible to Conveyance speed based on rotation [VmgCmm, '5ec) J is V B = hp ・(Wag/60)
--■ However, it is expressed by the following formula: h: height of head (mm) p: number of magnetic poles Wmg: number of rotations of the magnet body (rpm).

Conveyance speed based on rotation of developer carrier [Vsl (mm/
5ee)] is f, Vsl= D ・yr ・(WSI/'60)
--■ However, it is expressed by the following formula: D: developer carrier diameter (to) Wsl developer carrier rotation speed (rpm).

Therefore, the overall developer transport speed rVdev (mm
/5ee)] is expressed by the following formula: Vdev=Vmg-Vsl=(hp-Wmg-D-r-Wsl)/60-■.

By the way, the position closest to the developer carrier and the photoreceptor is
Therefore, the height of the head (h) is necessarily the distance between the nearest positions (dl
). Therefore, in order to prevent the developer from being present on the outer circumferential surface of the developer carrier downstream of the development area, D ・y ・Wsl>d+ ・p−Wmg −
It is sufficient to satisfy the expression −■. That is, the diameter of the developer carrier, the number of magnetic poles of the magnet, their rotational speed, the distance between the developer carrier and the photoreceptor, etc. may be set to satisfy Equation 0.

The developer used in the above development method consists of at least a resin-coated carrier and a toner.

First, the resin-coated carrier will be explained.

For ease of understanding, a cross-sectional view of the resin-coated carrier of the present invention is schematically shown in FIG. 1, and a schematic cross-sectional view of a conventional resin-coated carrier is shown in FIG.

That is, the resin-coated carrier of the present invention includes a carrier core material (1) and a resin coating layer (2) covering the carrier core material (1).
), consisting of 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 with I-toner (even if the toner has a small particle size). The toner can be charged quickly, each toner particle can be sufficiently uniformly charged, and toner scattering due to poor charging 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, the presence of pores causes frequent contact between toner and carrier, which is effective in preventing toner aggregation and further breaking up agglomerated toner, thereby solving the problem of toner aggregation.

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.

The diameter of each pore existing on the surface of the resin coating layer is 0.001-3
/711. Preferably 0.001-2 μm1. More preferably, the distribution is in the range of 0.005 to 2 μm. If the pore diameter is smaller than 0.001 μm, sufficient effect cannot be expected from the viewpoint of toner crushability, etc., and if the pore size is larger than 3 μm, the toner trapping property will be too strong, which may impair fluidity and developability. There is.

The average pore diameter corresponds to the pore diameter distribution range mentioned above.
The thickness is preferably in the range of 0.1 to 0.5 μm. 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 gram of carrier (CmQ/g) and total pore volume per coating resin layer II+IQ (IIIQ/+1Q).

The total pore volume (m12/g) per gram of carrier can be determined by mercury poronmetry. In the carrier of the present invention, the values are o, oot~0, I
mQ/g, preferably 0.01-0.051112/I
? It is desirable to have a value of . The value is 0.0011
1112/l? If it is smaller, there are insufficient pores present on the carrier surface, and there is a possibility that the effect of the pores may not be obtained. If it is larger than 0.1 mQ/i, there will be too many pores and the coating layer will become brittle. Coating resin 1
The total pore volume per mQ (+I++2/m(1)) can be determined by converting from the true specific gravity of the gear 1 coating layer and the carrier core material filling rate. In the carrier of the present invention, The value is 0.1 to 2+1112/II (1.

Preferably, it has a value of 0.5 to 1.5 mQ/mQ. Its value is 0, 1 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
If it is larger than m(1/mQ), there will be too many pores and the coating layer will become 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., use a material with a diameter of at most 100 μm. Specific materials include those known as two-component carriers for electrophotography, such as metals such as ferrite, magnetite, iron, nickel, and cobalt, and combinations of these metals with zinc, antimony, aluminum, lead, tin, bismuth, beryllium, and manganese. , alloys or mixtures with metals such as selenium, tungsten, zirconium, vanadium, metal oxides such as iron oxide, titanium oxide, magnonium 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, Epoquine resins, and polybutyral resins. resin, urea resin,
Various thermoplastic resins and thermosetting resins such as urethane/urea resins, rincon resins, polyethylene resins, and Teflon resins, and mixtures thereof, as well as copolymers, block polymers, graft polymers, and Polymer blends etc. are used. Furthermore, in order to improve charging properties, resins having various polar groups may be used.

In particular, when the toner used in combination with the carrier is a toner that easily becomes spent, a coating resin with good mold releasability, such as a silicone resin or a polyolefin resin, is preferred from the viewpoint of preventing spent.

The surface of the carrier of the present invention is preferably covered with carrier coating resin by 70% or more, preferably 90% or more, more preferably 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 9Qwt% or more, preferably 95wt% or more. The filling rate may be interpreted as indirectly regulating the resin coating layer thickness of the carrier, and if the carrier core material filling rate is less than 901%, the coating layer becomes too thick and is not applicable to the actual developer. However, the developer does not satisfy the required durability and charge stability 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 weight of the carrier core material, but as long as the carrier core material is applied, the specific gravity is 3.5 to 7.5, preferably 4.0 to 6.0, more preferably 4.0 to 6.0. 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 the carrier not being coated with an appropriate filling rate as described above will occur.

The electrical resistance of the resin-coated carrier of the present invention is l×lO″~
lXl0"Ω・C shoulder, preferably 108~1011Ω・
cm, more preferably about lO'' to 1012Ω·cwl. If the electrical resistance is less than 1×lO@Ω·clm, carrier development will occur and the image quality will deteriorate.
If it is larger than Xl0''Ω・cm, the toner will be charged excessively, making it impossible to obtain an appropriate image density.The electrical resistance can also be seen as an indirect expression of the resin coverage rate and carrier filling rate mentioned above. .

Preferably, the carrier used in the present invention further provides unevenness to the resin coating layer. Figure 2 shows the resin coating layer (2
) has an uneven surface, 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 coating layer uneven structure of the surface coating layer is expressed by the following formula [11;
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. ] 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 +00. The shape factor S can be measured, for example, using an image analyzer (Lucenox 5000; manufactured by Nippon Regulator Co., Ltd.); however, in general, when measuring the shape factor S, there is no significant difference depending on the model. It does not mean that it has to be measured.

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.

Examples of fine particles with a charge imparting function include Cry, Fe2
01, Fe, O,, IrO2, MnO2, MoC2, N
bO2, PtO2, TlO2, Ti2O3, Ti, O,
, WO2, V2O, , A Q 203, MgO, Sin
Specific examples include metal oxides such as , ZrO, and BeO, and dyes such as Nigron Base and Subiron Blank TRH.

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

Carbide such as TiC, MoC, ZrC, BN, NbN.

Examples include nitrides such as TiN and ZrN, and magnetic powders such as ferrite and magnetite.

Addition of metal oxides, metal heptadides, 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. This is believed to be because the addition of conductive fine particles such as carbon blank reduces the electrical resistance of the carrier to an appropriate degree, 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 the resin-coated carrier of the present invention, Bi magnetic powder is added to the resin coating layer. A carrier with better gradation reproducibility than the 1 carrier 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 an effect on the rise of charging.

The size, amount, etc. of the above-mentioned additives are determined by the pore morphology, coverage rate,
Although there is no particular limitation as long as the characteristics such as electrical resistance are satisfied, the size of the fine particles may be such that, in relation to the preferable manufacturing method of the carrier of the present invention described later, for example, particles that aggregate in a resin solution or in dehydrated hexane can be used. Any particle size is sufficient as long as it can be uniformly dispersed on the slurry without any particles, and specifically, the volume average particle size is 2 to 0. O1μ shoulder, preferably 1-0. It is sufficient if the OII is about 1m.

Further, as for the amount of the internal particles added, although the amount cannot be specified in part as described above, it is Q, lvt% to 5Qvt%, preferably 1Qvt% to the coating resin.
．． Qwt% to 4Qwt% is appropriate.

In particular, when the present invention 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. When the filling rate of the carrier is as small as 90 W [%] and the thickness of the coating layer is relatively thick, if such a carrier is used to make continuous copies of fine lines, a problem arises in that the reproducibility decreases. Such problems are solved by adding 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.

The fine particle components that can be used in this method include 7-Elai I
Examples include fine particles of metal oxides, halides or hydroxides of alkali metals or alkaline earth metals, transition metal complexes, etc.

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 carrying 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, it is good to add these additives and make them exist in the coating resin solution, or to form pores like ferrite etc. 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 coating 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, Japanese Patent Publication No. 60106808
The method described in the publication 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, it also improves the film strength.
A durable carrier with excellent adhesion between the core particles and the resin coating layer can be obtained.

The toner to be used in combination with the above is not particularly limited, and may include a pulverization method toner obtained by mixing and kneading a thermoplastic resin, a colorant, and/or a charge imparting agent, and then pulverizing and classifying the toner, or - a suspension-polymerized toner obtained by dispersing a colorant and/or a charge-imparting agent and polymerizing the same, or a liquid containing a colorant and a low softening point substance such as Wanx, or a fixing resin, etc., Capsule toner wrapped in a wall material (capsule shell) with a higher softening point than these, or photoconductive toner whose surface is covered with a photoconductive substance, with an average particle size of about 3 to 20 pm. do.

The developer thus obtained has excellent toner charge build-up, toner scattering prevention, and toner aggregation disintegration properties.

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 inside of the copying machine will be contaminated due to toner scattering, and the image will be Toner fog may occur.

FIGS. 4 and 5 show an example of a developing device used in the electrostatic latent image developing method according to the present invention. This developing device has a developer transport guide member (12) installed close to the upper half of the outer circumferential surface of the developer carrier (lO).
12) has an arc shape that is concentric with the developer carrier (10), and the developer supply section (A
) to the development area (B), the developer carrier (10) is placed at a substantially constant distance from the developer carrier (10). Note that this member (12) is made of an insulating material in this example, but
Even if it is a conductive material, it is sufficient if it is insulatively supported.

The height regulating plate (14) is disposed at a distance (d2) from the developer transport guide member (12) with a tip force j. Further, the tip of a scraper (15) is lightly pressed against the outer peripheral surface of the developer carrier (10).

In this developing device, the magnet (II) is rotationally driven in the direction of the arrow (b), and the developer carrier (lO) is also rotated in the direction of the arrow (b).
rotationally driven in the direction.

Next, the movement of the developer in the above-mentioned developing device will be explained.

The developer is supplied to the supply section (A) by a bucket roller (13), and is moved along the developer transport guide member (12) in the direction of arrow (c) based on the rotation of the magnet (11) in the direction of arrow (b). Then, the head height is regulated by a head height regulating plate (14) and conveyed.

The developer conveyed in the direction of arrow (c) on the developer conveyance guide member (I2) reaches the photoreceptor (1) at the tip of the member (12).
to develop the electrostatic latent image previously formed on the surface of the photoreceptor (1). At the same time, the developer is transferred to the developer carrier (
The developer carrying member (10) and the developer transport guide member (
12) in the direction of arrow (b), is scraped off by a scraper (15), and returned to the developer tank.

In this case, the position (X2) at which the developer ends contact with the surface of the photoreceptor (1) is a position that is approaching the surface of the developer carrier (10) or the photoreceptor (1), and both It is slightly above the nearest position (Xl) of . As a result, the current number is 11! ! The agent moves in the direction of movement of the photoreceptor (1) (arrow a)
There is no upper plate on the outer circumferential surface of the developer carrier (IO) on the downstream side of the closest position (Xl). Then, at the second position (X-) where the flow direction of the developer is changed,
Toner scattering, toner spillage, etc. are likely to occur, and by using the above-mentioned developer, toner charging has excellent build-up properties, and sufficient and appropriate charging is effectively imparted to the toner, and, Since toner aggregation does not occur, toner scattering, toner spillage, toner fog, etc. are suppressed.

Hereinafter, the present invention will be explained using specific examples (71).

(-) Toner production example Sue length Part by weight/Polyester resin +00 (softening point, 130
°C; Glass transition point, 5Q'C, AV25.0HV38
) ・Carbon bra/liquid 5 (manufactured by Mitsubishi Kasei Co., Ltd., MA#8) ・Dye 3 (manufactured by Toko Tsuchigaya Chemical Co., Ltd., Spiron Brasoku TRH) After thoroughly mixing the above materials in a ball mill, 14 o'ci
The mixture was kneaded on three heated rolls. After the kneaded material was left to cool, it was coarsely ground using a feather mill, and then finely ground using an etching mill.

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

Example of manufacturing carrier] (1) Preparation of titanium-containing catalyst component In a flask with an internal volume of 500 mQ purged with argon, add 200 mff8 of Ω-heptane dehydrated with a trowel at room temperature and 120 Ω-heptane in advance.
Magnetostearate and Rum 15y (25 mmol) dehydrated under reduced pressure (2 mmHg) at °C are added to form a slurry.

After 0.449 (2.3 mmol) of titanium tetrachloride was added dropwise with stirring, the temperature was started to rise, and the mixture was reacted under reflux for 1 hour to obtain a viscous and transparent solution of the titanium-containing catalyst component.

(2) Activity evaluation of titanium-containing catalyst component O1 to crepe dehydrated hexane 4QQm+1. 08 mmol of triethylaluminum, 08 mmol of diethylaluminum chloride, and 0.004 mmol as titanium atoms of the titanium-containing catalyst component obtained in the above (1) were collected and added.
Do not raise the temperature to 0°C. At this time, the system internal pressure is 1.5 kg
/cm2G. Next, hydrogen is supplied, 5,
After increasing the pressure to 5 ki/cm”G, the total pressure is 9,
5 kg/cm”G.
Polymerization was carried out for 1 hour to obtain 709 poly-7-. The polymerization activity was 365 #g/g-Ti・Hr, and the obtained t: ~IF R of the polymer (melt flowability at 190°C and 1 load of 2.16 kg: JIs K7
210) was 40.

(3) Reaction of titanium-containing catalyst component and filler and polymerization of ethylene. Sintered ferrite powder dried in an argon-substituted autoclave with an internal volume of IQ and dehydrated with 500 mL of hexane at room temperature and under reduced pressure (2 mmHg) at 200°C for 3 hours. F-20
0 (manufactured by Powder Chick, average particle size 70μl11) 45
09 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 0°C. The internal pressure of the system at this time is 1.5 kg
/ crn2G. Next, hydrogen is supplied and 2J1
After increasing the pressure to g/cm2G, the total pressure is increased to 6 to 9/crn”
Polymerization was carried out for 40 minutes while continuously supplying ethylene so as to maintain the temperature at G, 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 95.2vt%.

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 106μ
The mixture was classified using a No. m sieve to remove aggregates.

Carrier Production Example 2 In an argon-substituted autoclave with an internal volume of 1Q, in the same manner as in Production Example 1 (3), the titanium-containing catalyst component prepared in Production Example 1 (1) was added to 450 g of ferrite as titanium atoms. , 02 mmol was added and the reaction was carried out for 1 hour. After that, carbon black (Ketchen black D J
-600, manufactured by Lion Akzo Co., Ltd.) 0.47 g was added. The carbon blank 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, 2.0 mmol of triethylaluminum and 2.0 mmol of diethylaluminum chloride were added, and the temperature was raised to 90°C. The system internal pressure at this time was 1.5 kg/cra2G. Next, hydrogen was supplied to raise the pressure to 2 kg/cm"G, and then polymerization was carried out for 45 minutes while continuously supplying ethylene to maintain the total pressure at 6 kg/cm"G.
．． 3)? A polyethylene composition containing ferrite and carbon black was obtained. The dried powder had a uniform black color, and according to an electron microscope, it was observed that the surface of the 7-elite was thinly covered with polyethylene, and the carbon blank was uniformly dispersed in the polyethylene. In addition, when this composition was measured by TGA (thermal balance), the core filling rate was 95.9 wt%, and when calculated from the charged amount, 7elite, polyethylene, and carbon black were 24:
The weight ratio was 1:0.025. Thereafter, it was placed in a hot air stream set at 120°C and heat-treated for 2.0 hours.

The obtained carrier was classified using a 106 μm 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 1Q. Millimole of Ol was added and the reaction was carried out for 1 hour. After that, carbon black (1 knot) was added from the upper nozzle of the autoclave.
black) EC, manufactured by Lion Akzo) 0.
I threw in 50y. Naoriichi Ponburanoku is 200°
The product was dried under reduced pressure for 1 hour at C 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. The system internal pressure at this time was 1.5 hg/cm2G. Next, 37.5 mmol (21 g) of 1-butene was introduced, and then hydrogen was supplied to raise the pressure to 2 kg/cm2G, and then ethylene was continuously supplied to maintain the total pressure at 6 kg/cm2G. Polymerization was carried out for 1 minute to obtain a total amount of 467 g of a polyethylene composition containing ferrite and carbon blank.The dried powder had a uniform black color, and according to an electron microscope, the ferrite surface was thinly covered with a polymer, and the carbon black was It was observed that the composition was uniformly dispersed in the composition.When this composition was measured by TGA (thermal balance), the weight ratio of ferrite, polymer, and carbon black was 27+1:0.03. When the polymer from which the ferrite and carbon blank were removed by extraction (solvent, quinolene) was analyzed by [H], it was confirmed that it was a polyethylene copolymer containing 3W[%] 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 106μ
Classify with a sieve of m and remove aggregates.

Carrier production example 4 200 parts by weight of ferrite fine powder with an average particle size of 02 μm and a bisphenol type polyester resin (softening point, 123
°C, glass transition point = 65 °C, AV: 21, OHV: 43
, Mn Nia 600, Mw: 188400) were thoroughly mixed in a Hen/El mixer (10 fl) 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 an average particle size of 3.5 μm.

100 parts by weight of carrier core material (sintered ferrite powder F-200, manufactured by Powtertenoch, average particle size 70 μm) and 20 parts by weight of the child particles were mixed in a Hen/El mixer (10ff).
, mixed and stirred at 200 Orpm for 2 minutes,
The child particles were uniformly attached to 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 the positively chargeable control material Glo/Nbase EX (manufactured by Orient Kagaku Kogyo 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. The core material filling rate of the obtained carrier was 95.4 wt%.

Carrier Production Example 5 250 parts by weight of ferrite fine powder with an average particle size of 0.2 μm was added to a thermosetting/recone resin solution (KR-255: manufactured by Shin-Etsu Ricone 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 Tenok Co., Ltd., average particle size 70 μm) was used as the core material, and it was repeatedly applied to the core material using a spira coater (manufactured by Kaida Seiko Co., Ltd.) so that the core material was coated at 25 wt%. . Thereafter, the temperature in the system was raised to 150° C. to harden the resin, thereby obtaining a thermosetting resin-coated carrier in which fine ferrite powder was dispersed. This carrier was immersed in 6N H (l) for 2 hours, thoroughly washed with water, and dried under vacuum at 60°C for 5 hours to obtain a resin-coated carrier with pores on the surface.The resulting carrier was filled with a core material. The rate was 91°5vt%.

Carrier Production Example 6 An acrylic resin solution with a solid ratio of 2% (Acrydec A405: manufactured by Dainippon Ink Co., Ltd.) was used as the coating liquid, and sintered ferrite powder (F-200: manufactured by Powder Chick Co., Ltd., average particle size: 70 μm) was used as the core material. ) to the core material using a spira coater (manufactured by Kaida Seiko Co., Ltd.). The coating was applied to obtain a coating of Ovt%. Thereafter, the temperature in the system was raised to 150° C. to cure the resin, thereby obtaining a thermosetting acrylic resin-coated carrier. The core material filling rate of the obtained carrier was 99.0w1%.

Total pore volume per ly of carriers obtained in carrier production examples 1 to 6 (m (+/h), total pore volume per 1 mQ of coating layer (mQ/mQ), average pore diameter (μm), Ferrite content (wt%), true specific gravity (g/c), bulk specific gravity (ri7
cm3), electrical resistance and specific surface area (m'/g) in Table 1.
Shown in t2.

Note that the total pore volume and average pore diameter of Gearia are values calculated from the measurement results of carrier pore distribution.

The pore distribution of the carrier was determined by Mercury Polo/Me;
The measurement was carried out using Poresizer 9310 (manufactured by Takasugi Seisakusho Co., Ltd.).
Contact angle of mercury: 130°Surface tension: 484 dyn/'c
It was set as m. The results are shown in FIGS. 6 to 11.

FIG. 6 is a diagram showing the relationship between pore diameter and intrusion volume. The intrusion volume represents the pore volume into which mercury was injected up to the maximum pressure at the time of measurement.

FIG. 7 to FIG. 1I 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, 1 mg.

- Pycnometer pycnometer with Gelysanok thermometer specified in JLS R3501 (glassware for analytical chemistry), internal volume 50mQ.

・Constant-temperature water tank: One that can maintain the water temperature at 23°C to 05°C.

@7. Measurement was carried out using a measuring device according to the following procedure.

■Accurately weigh the mass of the pre-dried vicinometer to the nearest O, l 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 of the constant temperature water tank, wipe off the water from the outside, and reduce its mass to 0, 1.
Weigh accurately to the milligram.

■Next, after emptying the vicinometer, sample 10 to 1
Sample the sample for 5 hours, weigh it again accurately to the digits of 0, ] mg, and subtract the result from (■) to determine the mass of the sample.

■ Gently add 20 to 30 mQ of butane to the vicinometer containing the sample to completely cover the sample, and then gently remove the air in the liquid in a vacuum defucter.

0 Next, the pycnometer was degassed to the vicinity of the marked line.
Fill with heptane and keep in a constant temperature water bath at 05°C for 1 hour. After aligning it accurately with the marked line on the liquid surface, take it out, completely wipe off the water on the outside, and weigh it as 0.1 mg.
Weigh accurately to the nearest digit.

■Specific gravity is calculated using the following formula.

S -a-b,,'(b-c+a) Here, S: specific gravity a: Mass of sample (g) b. Pour the immersion liquid up to the marked line on the pycnometer. Mass when inserted (g) Pycnometer marking line containing C0 sample Mass when filled with immersion liquid up to (J) d, specific gravity of the immersion liquid at 23°C The bulk specific gravity was based on JIS Z2504.

The electrical resistance is measured using a circular metal electrode with a thickness of l north and a diameter of 50 mm.
Place the sample so that it is connected to the
A card electrode with an inner diameter of 38 mm and an outer diameter of 42 mm was placed on the sample, and the current value after 1 minute when a DC voltage of 500 V was applied was read and converted into the volume resistivity p of the sample. The measurement environment was a temperature of 25 degrees and a relative humidity of 55 ± 5%.
It was repeated twice 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 Takasu Seisakusho Co., Ltd.).

Evaluation of charging rise property A toner mixing ratio of 2 wt% was obtained from the carriers of Production Examples 2 and 6 (=comparative example) and the toner obtained in the above Production Examples.
Using a developer adjusted to
The amount of charge (q) during developer mixing time was measured by the method described in "Determination of developer charging speed", No. 3 (1988).

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

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

It can be seen that Keylia of Production Example 2 has a charging rise characteristic that is lower than that of Carrier I of Production Example 6 (-Comparative Example).

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

Evaluation using a developing device Using a developing device configured as shown in Figure 4, B was obtained under the following conditions.
2000 sheets of originals with a /W ratio of 35% were copied, and toner fog was visually evaluated.

Developer carrier: Diameter +31mrn Rotation speed: 70 rprh Development bias ++50V (DC) Magnet: Number of poles 28 Magnetic force 100OG (on the surface of developer carrier) Rotation speed
:130Orpm Closest position interval (d+): 0,5 mm Brush height regulation interval (d2): 15+nm Distance between developer transport guide member and photoreceptor (+L): 10 mm Between developer transport guide member and developer carrier interval (d,)
:1.2 Fighting photoconductor.

Peripheral speed: 130 mm/see Maximum potential of electrostatic latent image: +500V Carrier used: Production Example 2 and Production Example 6 (Comparative Example) Toner mixing ratio: 5 wt% At the initial stage of copying, a developer using the carrier of Production Example 6 was used. (hereinafter referred to as the "comparative developer") had a level of fog that would pose no practical problem, but still, the developer using the carrier of Production Example 2 (hereinafter referred to as the "developer of the present invention")! = It was a little inferior in comparison.

As the number of copies increased, the toner fog of the comparative developer worsened compared to the initial stage, and after Iooo copies had been made, the toner fog became more significant than that of the developer of the present invention. In addition, image quality deteriorated and toner scattering became more severe.

After copying 2000 sheets, toner fog occurred in the comparative developer to such an extent that it became a practical problem. On the other hand, with the developer of the present invention, even after 2,000 copies were made, the level of toner fog was the same as in the initial stage.

Effects of the Invention A developing method in which contact between the developer and the surface of the electrostatic latent image carrier is terminated at a position where the developing electrode is approaching the surface of the electrostatic latent image carrier or at a position where it is closest to the surface of the electrostatic latent image carrier. By using a developer combined with a carrier having pores, toner charging performance is excellent, toner scattering, toner spillage, and toner fog are improved, and B
It has become possible to stably obtain good images even when copying originals with a high /W ratio or when using under various environments.

[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. FIG. 4 is a sectional view showing an example of a developing device for carrying out the present invention. FIG. 5 is a sectional view of the main part. FIG. 6 is a diagram showing the relationship between the pore diameter of the carrier surface pores and the intrusion volume. FIGS. 7 to 11 are diagrams showing the relationship between the pore diameter and volume fraction of carrier surface pores obtained in each carrier production example. FIG. 12 is a diagram showing the relationship between the developer mixing time and the rise in toner charge amount. Patent Applicant Minolta Camera Co., Ltd. Representative Patent Attorney Aoyama Ao Haka 1 name drawing 2 drawings 4 drawings Fig. 11 @ Hole Iso / [Pml Existing tank Imashin / [%ko Fig. 12 +g /r This time / second

Claims (1)

[Claims] 1. Arranged to face the electrostatic latent image carrier and transport the developer;
At a position where a developing electrode for developing an electrostatic latent image formed on the surface of the electrostatic latent image carrier is approaching or closest to the surface of the electrostatic latent image carrier, the developer is electrostatically An electrostatic latent image developing method in which contact with the surface of a latent image carrier is terminated, characterized in that a resin-coated carrier having a large number of pores on the surface is used as a carrier that is a component of the developer. Electrostatic latent image development method.