JP2003005507A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device that prevents an image density from decreasing even in repeated copying or long time use, and steadily supplies a high quality image free from fog, carrier attachment, blotch, etc. SOLUTION: In the image forming device of a cleaner-less system, developer has negatively-chargeable non-magnetic toner and magnetic carrier particle having a resin constituent on its surface. A developer carrier has at least a substrate and a conductive covering layer provided on the substrate. A frictional charge quantity of the magnetic carrier after the non-magnetic toner is removed from the surface of the developer carrier is equal to or less than 0.01 mC/kg.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for developing an electrostatic latent image formed on a latent image holding member such as an electrophotographic photosensitive member or an electrostatic recording dielectric member in electrophotography to visualize the latent image. The present invention relates to an image forming apparatus used.

[0002]

2. Description of the Related Art Conventionally, image forming apparatuses such as copying machines, printers, and facsimiles using a transfer type electrophotographic system are
In general, a rotating drum type photoconductor using a photoconductive substance is used as an image carrier, and a charging step of uniformly charging the rotating photoconductor to a predetermined polarity and potential by a charging means, the rotation photoconductor is made uniform. An image exposure process for forming an electrostatic latent image corresponding to the exposure image information by performing image exposure on the charged surface by image exposure means (laser light scanning exposure means, original image projection and image formation exposure means, etc.), formed static image. A developing step of developing the latent image as a toner image by the developing means, a transferring step of transferring the toner image from the photoconductor side to a transfer material such as paper by the transferring means, and a toner image of the transfer material separated from the photoconductor is fixing means. Fixing process to fix the surface of the transfer material with heat or pressure, and a cleaning process for cleaning the surface of the photosensitive material by removing the toner not transferred to the surface of the photosensitive material after transferring the toner image to the transfer material. By executing the image formed by those obtained image forming material (copies, prints). The cleaned photoreceptor is repeatedly used for image formation.

As the above-mentioned process means, various methods and configurations are specifically known. In recent years, such image forming apparatuses have been downsized,
There is a limit to downsizing only by downsizing the image bearing member and each process means device constituting the apparatus. Further, the toner remaining on the surface of the photoconductor after the transfer of the toner image to the transfer material is removed by the cleaning means (cleaning device) to become waste toner, but in view of environmental protection and effective use of resources, It is desirable not to produce waste toner.

Therefore, the developing means also serves as a cleaning means for cleaning the toner remaining on the surface of the photoconductor after the transfer of the toner image onto the transfer material, thereby eliminating the need for a cleaning means as a dedicated device. Or "cleanerless" image forming apparatus has appeared (JP-A-59-133573, JP-A-6-133573).
No. 2-203182, No. 63-133179, No. 64-20587, JP-A-2-511168.
No. 2, No. 2-302772, No. 5-2287, No. 5-2289, No. 5-53482, No. 5-61383).

Simultaneous development cleaning transfers transfer residual toner on the photosensitive member from the transfer portion to the developing portion, and transfers it to the toner carrier (toner supply member, developing member) of the developing means at the time of development after the next step. Fogging removal potential difference V, which is the potential difference between the DC voltage applied to the carrier and the photoreceptor surface potential.
It is something that is collected by back. According to this, even if there is no cleaning device as a dedicated device, the transfer residual toner is collected by the developing means and used for the development in the subsequent steps, so that the waste toner can be eliminated. Further, since no cleaning device is provided as a dedicated device, there is a great advantage in terms of space, and the device can be significantly downsized.

Further, in the developing process in which the electrostatic latent image formed in the image forming process in the image forming apparatus is developed as a toner image by the developing means, generally, the toner particles charged to the opposite polarity to the latent image are statically charged. Although it is attracted by electric attraction and attached to an electrostatic latent image (in the case of reversal development, toner having a triboelectric charge having the same polarity as the charge of the latent image is used), but such a development method is large. Separately, there are a method of using a two-component developer in which a small amount of toner and a carrier are mixed, and a method of using a so-called one-component developer containing toner alone without using a carrier.

By the way, although the electrophotographic method has reached a satisfactory level for document copying, due to the development of computers and the development of high-definition, output images of full-color images are processed at the time of digital image processing and development. High image quality and high quality have been sought by using various methods such as application of an alternating electric field, and further high image quality and high quality are desired in the future.

Conventionally, a two-component developer has been mainly used to output a full-color image. Carriers that constitute such two-component developers are generally classified into conductive carriers represented by iron powder and so-called insulating carriers in which magnetic particles such as iron powder, nickel and ferrite are coated with an insulating resin. To be done. When an alternating electric field is applied to measure high image quality, if the resistance of the carrier is low, the latent image potential leaks to the carrier, and a good developed image cannot be obtained. Therefore, the carrier needs to have a certain resistance or more. . When the carrier core is conductive, it is preferable to coat the carrier core with a resin or the like before use. Further, ferrite having a high resistance to some extent, magnetic substance-dispersed resin particles and the like are preferably used as the core material.

In general, iron powder has a high magnetic force, so that in the developing area where the toner in the developer develops a latent image, the magnetic brush of the developer becomes hard, resulting in blemishes and scratches. Therefore, it is difficult to obtain a high quality developed image. Therefore, in order to reduce the magnetic force of the carrier and achieve high image quality, ferrite or a magnetic material-dispersed resin carrier is preferably used.

Further, in the case of the magnetic substance dispersion type resin carrier, since the specific gravity is smaller than that of iron powder or ferrite, the strength of magnetization per unit volume becomes smaller and the share for toner is small, so that the high image quality is obtained. In addition to high performance, high developer durability can be achieved. Therefore, magnetic substance-dispersed resin fine particles having high resistance to some extent are preferably used as carriers.

The developer carrying member used in the conventional developing method as described above is, for example, formed by molding a metal, an alloy or a metal compound into a cylindrical shape, and the surface thereof is subjected to electrolysis, blasting, sanding, etc. to have a predetermined surface roughness. What was processed to become is used. Among these metals and alloys, aluminum and alloys mainly containing aluminum are preferably used from the viewpoint of workability.

However, with the above-mentioned materials, the sleeve is likely to be deformed during blasting, and as a result, image unevenness is likely to occur.
Further, these materials have a problem in terms of durability such that the surface is abraded by friction with the carrier and the carrier carrying force is reduced. For example, a material such as stainless steel is a material having good strength, but it is difficult to process, and the material cost is
It is disadvantageous in terms of processing cost.

Further, as the two-component developer carrying member, one obtained by molding the above-mentioned metal, alloy or metal compound into a cylindrical shape and treating the surface thereof by electrolysis, blasting, sanding, etc. so as to have a predetermined surface roughness is used. In this case, in the two-component developer layer formed on the surface of the developer carrier by the developer layer thickness regulating member, the magnetic substance-dispersed resin fine particle carrier and the non-magnetic carrier in the developer layer existing near the surface of the developer carrier are Since the magnetic toner has an extremely high electric charge, the toner is strongly attracted to the surfaces of the carrier and the developer carrier, and it becomes impossible to rub the toner with the carrier and the toner with the developer carrier. Further, so-called blotch occurs in which the developer coating on the developer carrier becomes uneven. When an image is formed under such a condition, the image is not sufficiently developed, resulting in an image with reduced image density, scattered characters, and fog.

Further, when the transfer residual toner on the photosensitive member after the transfer process is removed / collected / reused by cleaning at the same time as development, the toner collected by the magnetic brush portion is stored in the developing device as the developing sleeve rotates. Although it is conveyed and frictionally charged to a predetermined value by rubbing against the carrier, the amount of frictional charge of the collected toner is not always the same as that of the toner replenished in the developing device. This causes non-uniformity of the triboelectric charge amount of the toner in the developing device. The collected toner is likely to exist in the vicinity of the developing sleeve, and may be conveyed to the developing area before being agitated well and frictionally charged, or when the toner as described above is charged up and the carrier surface and the sleeve. When the toner adheres to the surface, or the toner does not have an opportunity to rub against the carrier, the toner may not have a suitable electric charge.

Further, when it adheres to the surface of the sleeve, the developer coat becomes non-uniform, and it becomes impossible to have sufficient transportability. In particular, in recent years, it has been desired to make the toner spherical so as to improve the transferability of the developer and realize cleanerlessness of the photoreceptor, and such a spherical toner is used as the above magnetic substance-dispersed resin fine particle carrier. Even when used together, the toner tends to be charged up and adheres to the surface of the carrier and the sleeve, and the charge amount of the toner tends to decrease accordingly. For this reason, when an image is formed under such a condition as described above, sufficient development is not performed, resulting in an image with many blotches, reduced image density, and scattered characters. In addition, in particular, when the toner has a small particle size, the variation in charge of each toner becomes large, and it becomes more difficult to control the developing property thereof.

Further, in a developer containing a magnetic substance-dispersed resin fine particle carrier as a component, the triboelectrification property to the toner is unstable as compared with the ferrite type carrier, and the developer as described above can be formed. There is a problem that fogging occurs in the visual image. That is, when such a developer is used, the toner particles adhere to the surface of the magnetic substance-dispersed resin fine particle carrier with the use thereof, so that the electric resistance of the carrier particles increases and the bias current decreases. Moreover, the triboelectric charging property becomes unstable, and as a result, the image density of the formed visible image is lowered and the fog is increased.

On the other hand, as a developer carrying member, in order to prevent the generation of a developer having an excessive electric charge and the firm adhesion of the developer, a conductive material such as carbon black or graphite is contained in a triboelectrically chargeable resin. A method for forming a film in which a solid lubricant is dispersed on the above-mentioned developer carrier base is disclosed in JP-A-01-277265. These techniques are also effective for adhesion of a two-component developer to a developer carrier and blotch. Further, as an additional effect, it is possible to use an aluminum base material and reduce the cost by selecting a material for the resin coating layer having abrasion resistance.

Further, the resin coating layer of the developer carrying member also has a function of imparting an appropriate electric charge to the toner. Even in the two-component developer, the toner is charged not only by friction with the carrier but also by friction with the developer carrier. In addition, electrification due to friction occurs between the developer carrying member and the carrier particles. In particular, when a magnetic substance dispersed resin fine particle carrier having a relatively high resistance is used, the triboelectrification property between the developer carrying member and the carrier has a great influence on the developability. For example, if the carrier and the developer carrying member have an inadequate frictional electrification property, the charge of the toner causes the toner to strongly adhere to the carrier, which lowers the developability and accelerates the spent of the carrier. Further, since the toner is not appropriately charged, there is a possibility that toner having a charging polarity opposite to the normal polarity may be generated. This opposite polarity charged toner is
It tends to adhere to the white portion of the image to be framed and cause the problem of reverse fog.

Further, when the magnetic substance-dispersed carrier is strongly charged to the opposite polarity to the toner, so-called carrier fog (adhesion) that adheres to the non-image portion of the photosensitive member occurs. Simultaneous development cleaning removes transfer residual toner
In the cleanerless type image forming apparatus for collecting,
When the fogging removal bias (Vback) is adjusted to an appropriate value in order to prevent reversal fogging and carrier adhesion, reverse transfer toner recovery may be deteriorated. Therefore, it is important to control the triboelectric charging property of the developer carrying member and the carrier particles. Further, a coating layer forming material for that purpose is required.

[0020]

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a material for forming a suitable triboelectric relationship between a developer carrier and a carrier, and between a developer carrier and a toner. By doing so, it is to provide an image forming apparatus suitable for a cleanerless system. It is also an object of the present invention to prevent the charge-up and the toner sticking on the carrier sleeve from being associated with the developer, even when a highly transferable spherical toner useful for a cleanerless system is used. An object of the present invention is to provide an image forming apparatus capable of suitably controlling charging properties and transportability and effectively preventing fog, blotch, image density reduction, carrier adhesion, and character scattering. Further, an object of the present invention is to form an image with which a stable image can be obtained even when using a developer carrier having good processability and low cost, which has excellent abrasion resistance and long-term durability in any environment. It is to provide a device.

[0021]

The above object can be achieved by the present invention described below. That is, the present invention is an image carrier,
Charging means for charging the surface of the image carrier, information writing means for forming an electrostatic latent image on the charged image carrier, a developer carrier for carrying the developer contained in the developing container, A developer layer thickness regulating member for regulating the layer thickness of the developer carried on the developer carrying body, the developer carried on the developer carrying body, and the developer carrying body and the electrostatic latent image holding body. To a developing area opposed to each other, a means for developing the electrostatic latent image formed on the latent image carrier, a transfer means for transferring the visualized developer image onto a transfer material, and a transfer means on the transfer material. At least a fixing unit for heating and fixing the transferred transfer image, and a unit for developing the electrostatic latent image transfers the developed image to a transfer material, and then collects the developer remaining on the latent image holding member. In the image forming apparatus that also serves as a cleaning unit, A two-component developer comprising an electrically conductive non-magnetic toner and carrier particles having magnetism, wherein the carrier particles of the two-component developer have a resin component on at least the surface thereof, and the developer carrying member comprises at least a substrate and An image formation having a conductive coating layer provided on the substrate, wherein the triboelectric charge amount of the carrier when the non-magnetic toner on the developer carrying member is removed is 0.01 mC / kg or less. Provide a device.

In the present invention, the carrier is more preferably a magnetic substance-dispersed carrier in which a magnetic substance is dispersed in a binder resin, and the conductive coating layer on the developer carrying member is at least More preferably, it is formed of a resin composition containing a binder resin and conductive fine particles dispersed in the binder resin, and in the resin composition of the coating layer provided on the developer carrier. It is more preferable that the image forming apparatus contains a copolymer containing a vinyl polymerizable monomer and a nitrogen-containing vinyl monomer.

Alternatively, in the image forming apparatus, the nitrogen-containing heterocyclic compound dispersed in the binder resin, particularly the imidazole compound, is contained in the resin composition of the coating layer provided on the developer carrying member. It is preferable. Further, in the coating layer on the developer carrying member, the number average particle diameter is 0.3 to
It is preferable that the image forming apparatus contains spherical particles of 30 μm, and particularly conductive spherical particles having a true density of 3 g / cm ³ or less.

Further, a developer charge amount control unit located upstream of the charging unit for charging the developer on the surface of the image carrier, and an upstream of the developer charge amount control unit and a downstream of the transfer unit. And a means for uniformizing the residual developer image remaining on the surface of the image carrier after the developer image is transferred to the transfer material, and remaining on the image carrier after the developer transfer. The residual developer image to be made uniform by the residual developer image uniformizing means, and the uniformed residual developer on the image carrier is charged to a normal polarity by the developer charge amount controlling means, and the charging means It is preferable that the image forming apparatus charges the surface of the image bearing member at the same time with an appropriate charge amount.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to the preferred embodiments. In the image forming apparatus of the present invention, the carrier particles have a resin component on at least the surface thereof, and the developer carrying member has at least a base and a conductive coating layer provided on the base. ,
The amount of triboelectricity of the carrier on the developer carrier is 0.0
1 mC / kg or less, more preferably 0.005 mC / k
It is preferably in the range of g to -0.01 mC / kg.

Generally, when a negatively chargeable toner is used, the carrier is likely to be positively charged. This tendency becomes particularly strong when a carrier coating agent that is easily positively charged is used. As a result, when the chargeability of the carrier is increased to the positive charge side (the chargeability of the developer carrying member is negative with respect to the carrier), the contact area of the carrier is wider than that of the developer carrying member. In this case, the negative charging is increased, the toner charge-up phenomenon is likely to occur, and the blotch, the image density decrease, and the fog are likely to occur. Further, the carrier is likely to be attached to the non-image portion of the drum (image bearing member) because the positive charging property of the carrier is enhanced.

In the present invention, the chargeability of the carrier is set to a weak positive to
By configuring the surface of the developer carrier so as to be negative, the carrier and the developer carrier can appropriately impart triboelectric charging to the toner, and suppress the generation of toner charged to the opposite polarity. You can As a result, the latitude of reversal fog is widened, and in particular, in the cleanerless type image forming apparatus that removes and collects the transfer residual toner by simultaneous cleaning at the time of development as in this configuration, a wide fog removal bias (Vback) is set and the transfer residual toner is removed. Even when the toner recoverability is improved, it is possible to suppress the reversal fog. In addition, the above-mentioned blotch, decrease in image density,
It is possible to prevent the carrier from adhering and to be generated, and to provide a good image. In particular, it has been found that it is possible to suitably set the triboelectric charge of the carrier and the toner by using a positively chargeable material as the constituent material of the developer carrier coating layer.

The frictional charge of the carrier in the present invention with respect to the developer carrying member is measured by the following method. The developing device in the image forming apparatus to be used is filled with only the carrier actually used in the developing process. And 23.
The carrier carried on the developer carrying body was rotated by idling for 1 minute in a room temperature and normal humidity (N / N) environment of 5 ° C. and 60% RH, and then the carrier carried on the developer carrying body was subjected to a metal cylindrical tube and a cylindrical filter as shown in FIG. The amount of electric charge Q, which is collected by suction and stored in the condenser through the metal cylindrical tube, and the mass of carrier M, which is collected
From the above, the charge amount Q / M (mC / kg) per unit mass was calculated and used as the triboelectric charge amount of the carrier.

In the present invention, in order to prevent the developer from being fixed on the developer carrying member due to charge-up and the charge imparting failure from the surface of the developer carrying member to the developer due to the charge-up of the developer. The developer carrying member is composed of a conductive coating layer. Then, it is desirable that the coating layer is made conductive by forming the coating layer from a resin composition containing at least a binder resin and conductive fine particles dispersed in the binder resin.

As the binder resin used for forming the conductive coating layer of the developer carrying member, generally known resins can be used. For example, phenolic resin, epoxy resin,
Polyamide resin, polyester resin, polycarbonate resin, polyolefin resin, silicone resin, fluorine resin, styrene resin, vinyl resin, cellulose resin, melamine resin, urea resin, polyurethane resin, polyimide resin Examples thereof include resins and acrylic resins. Considering the mechanical strength required for the developing sleeve, a thermosetting resin is more preferable, but a thermoplastic resin is also applicable as long as it has sufficient mechanical strength.

In the present invention, the volume resistance value of the conductive coating layer is preferably 10 ⁶ Ω · cm or less, more preferably 10 ³ Ω · cm or less. That is, when the volume resistance value of the coating layer exceeds 10 ⁶ Ω · cm, a defect in imparting charge to the developer is likely to occur, and as a result, blotches are likely to occur.

In the present invention, in order to adjust the resistance value of the coating layer to the above value, it is preferable to include the following conductive substances in the coating layer. Examples of the conductive material used in this case include metal powders such as aluminum, copper, nickel and silver, metal oxides such as antimony oxide, indium oxide and tin oxide, carbon fiber, carbon black and graphite. Examples include carbonaceous materials.

In the present invention, of these, carbon black, particularly conductive amorphous carbon, is particularly excellent in electrical conductivity and is filled in a polymer material to impart electrical conductivity, or the amount added is controlled. It is preferably used because it can obtain an arbitrary conductivity to some extent. Further, the preferable addition amount of these conductive substances in the present invention is in the range of 1 to 100 parts by mass with respect to 100 parts by mass of the binder resin.

Further, in the present invention, in order to further reduce the adhesion of the developer to the surface of the developer carrier, a solid lubricant can be mixed in the coating layer. Examples of solid lubricants that can be used in this case include molybdenum disulfide, boron nitride, graphite, graphite fluoride, silver-selenniobium, calcium chloride-graphite, and talc. The addition amount of these solid lubricants that can be used in the present invention is preferably in the range of 1 to 100 parts by mass with respect to 100 parts by mass of the binder resin.

In the developer carrier of the present invention, it is preferable that the coating layer contains a positively chargeable material, and it is particularly preferable that a nitrogen-containing compound is contained. Examples of such a material include a resin composition containing a copolymer containing a vinyl polymerizable monomer and a nitrogen-containing vinyl monomer. Since the binder resin contained in the resin coating layer has a copolymer of a vinyl polymerizable monomer having high mechanical strength and a nitrogen-containing vinyl monomer having high negative triboelectrification property to a developer, The agent carrier has high abrasion resistance of the resin coating layer and high toner adhesion / fusion resistance, and has good triboelectrification characteristics until it is used for many sheets. Further, it is also effective in suppressing carrier adhesion onto the drum due to positive charge of the carrier. In particular, when the carrier has a positive coat layer, it is more effective.

Further, since this copolymer has the nitrogen-containing vinyl monomer, the dispersibility of the conductive fine powder such as carbon black and graphite in the resin coating layer is improved. Therefore, the electrical resistance of the resin coating layer is favorably reduced, the uniformity of the triboelectric charging property on the surface of the resin coating layer is improved, the triboelectric charging property for the developer is higher, and the charge amount of the developer is higher. Since the distribution becomes sharper and the film strength of the resin coating layer itself is improved, the durability of a large number of sheets is further improved.

The reason why the dispersibility of the conductive fine powder such as carbon black and graphite in the resin coating layer is improved by having the nitrogen-containing vinyl monomer in the copolymer is not clearly understood. By containing a polar group based on the nitrogen atom in the nitrogen-containing vinyl monomer,
Since the solubility in a solvent, particularly a solvent having polarity, is improved, the wettability of the solution in which the resin is dissolved to the conductive fine particles is improved, and the resin is formed by coating the conductive fine particles in the solution. It is considered that the dispersibility of the conductive fine particles in the resin coating layer is improved when the coating layer is formed. In particular, when the conductive fine particles are a substance such as carbon black having a polar group on the surface, the affinity is further increased by the polar group based on the nitrogen atom, which is more effective.

In the present invention, the copolymerization molar ratio of the copolymer having the vinyl polymerizable monomer (M) and the nitrogen-containing vinyl monomer (N) preferably satisfies M: N = 4 to 999: 1. When M exceeds 999, there is almost no effect of adding the nitrogen-containing vinyl monomer, that is,
The effect of improving the triboelectrification property is extremely small, and the effect of copolymerization is hardly seen. When M is less than 4, or when a specific nitrogen-containing vinyl monomer is used, for example, the resin layer is not stable due to a decrease in Tg, and the charge of the resin layer is imparted by the temperature rise of the electrophotographic apparatus main body. There is a possibility that the characteristics of abrasion resistance will be impaired and that the toner will be easily fixed. Further, even if the ratio of the nitrogen-containing vinyl monomer is further increased, the effect of imparting charge is saturated, so that it is not particularly required.

In the present invention, examples of the vinyl polymerizable monomer which can be the main component of the above-mentioned copolymer include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate and n-butyl (meth) acrylate. , Iso-butyl methacrylate, cyclohexyl (meth) acrylate, dimethyl (amino) ethyl methacrylate, diethyl (amino) methacrylate, hydroxyethyl (meth) acrylate, styrene, α-methylstyrene, acrylic acid, methyl acrylate, ethyl acrylate, Butyl acrylate, dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, methacrylic acid, methyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, metha A monocarboxylic acid having a double bond such as lilonitrile or acrylamide, or an ester compound thereof; for example, a dicarboxylic acid having a double bond such as maleic acid, butyl maleate, methyl maleate or dimethyl maleate, and an ester compound thereof; And the like, and these can be used alone or as a mixture of two or more kinds. In particular, the inclusion of an acid monomer or acid ester monomer having a vinyl group is effective for the charge stability of the developer on the developer carrier. In that case, as the effect of stabilizing the triboelectric charge amount, it is slightly better to use the acid monomer than the acid ester monomer.

In the present invention, it is preferable to use methyl methacrylate as the vinyl polymerizable monomer. When used as a polymer, methyl methacrylate has excellent mechanical strength. Further, when it is used as a binder resin for the sleeve surface layer, the triboelectric charging property to the developer is good. However, when used as a homopolymer, the triboelectric charge imparting property is often insufficient, and the dispersibility of pigments such as carbon black and graphite is not so good. By using as a copolymer containing a nitrogen-containing vinyl monomer as in the present invention,
The triboelectric charging property can be improved. In addition, in the present invention, since the methyl methacrylate component is preferably contained in a ratio of 80% by mass or more, even if compared with the homopolymer of methyl methacrylate, mechanical strength,
For example, it does not impair wear resistance. Further, since the nitrogen-containing vinyl monomer component is contained, the dispersibility is improved when the pigment component such as the conductive fine powder is dispersed in the resin layer. Is preferred.

Further, in the present invention, the above-mentioned copolymer may contain other vinyl-based monomer units, but the vinyl-polymerizable monomer (M) is based on all the monomers constituting the copolymer. , Preferably 70-99.
It is preferable that the content of the nitrogen-containing monomer (N) is less than 9 mol%, and the nitrogen-containing monomer (N) is preferably contained in an amount of less than 0.1 to 20 mol% based on all the monomers constituting the copolymer. It is good in terms of the abrasion resistance of the coating layer and the property of imparting triboelectric charge to the developer.

70 mol% of vinyl polymerizable monomer (M)
If it is less than 9, the mechanical strength of the resin coating layer is likely to decrease, and the abrasion resistance may be impaired.
In the above cases, the triboelectric charge imparting property to the developer cannot be sufficiently obtained. Nitrogen-containing monomer (N) is 0.1 mol%
If it is less than 20 mol%, the triboelectric charge imparting property to the developer cannot be sufficiently obtained, and if it is 20 mol% or more, for example, T
There is a possibility that the resin layer will not be stable due to the decrease of g, and that the temperature rise of the main body of the electrophotographic apparatus will impair the charge imparting property and abrasion resistance of the resin layer and that the toner will be easily fixed. Also,
Even if the ratio of the nitrogen-containing vinyl monomer is increased more than this, the effect of imparting charge is saturated and is not particularly required.

The resin binder used in the present invention has a weight average molecular weight Mw of 3,000 to 5,000.
It is preferably in the range of 50,000. Molecular weight Mw
When the value is 3,000 or less, the amount of the low molecular weight component is too large, so that the toner easily adheres to or sticks to the sleeve, and the charge imparting property of the resin deteriorates. Also 50,000
If it exceeds the above range, the molecular weight is too high, and since the resin viscosity in the solvent is high, it causes poor coating and dispersion when pigments are added, and the composition of the resin layer becomes uneven. This may cause unstable toner charging, unstable surface roughness, and reduced abrasion resistance.

The Mw / Mn, which represents the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the resin binder used in the present invention, is preferably 3.5 or less.
When Mw / Mn exceeds 3.5, the low molecular weight component increases, so that the adhesion of the toner and the fusion are increased, and the property of imparting triboelectrification to the toner is likely to decrease.

In the present invention, GPC as a resin binder
The molecular weight distribution of the chromatogram according to is measured as follows. That is, the column is stabilized in a heat chamber at 40 ° C., THF as a solvent is allowed to flow at a flow rate of 1 ml per minute, and about 100 μl of a THF sample solution is injected into the column at this temperature for measurement. In measuring the molecular weight of the sample, the molecular weight distribution of the sample was calculated from the relationship between the logarithmic value and the count number of a calibration curve prepared from several kinds of monodisperse polystyrene standard samples.

As the standard polystyrene sample for preparing the calibration curve, for example, a standard polystyrene sample having a molecular weight of about 10 ² to 10 ⁷ manufactured by Tosoh or Showa Denko is used, and a standard polystyrene sample having at least about 10 points is used. Appropriate.
An RI (refractive index) detector is used as the detector. As the column, it is preferable to combine a plurality of commercially available polystyrene gel columns, for example, Shodex GPCKF-801, 802, 80 manufactured by Showa Denko KK
Combination of 3, 804, 805, 806, 807, 800P, etc. and TSKgel G1000H manufactured by Tosoh Corporation
(HXL), G2000H (HXL), G3000H
(HXL), G4000H (HXL), G5000H
(HXL), G6000H (HXL), G7000H
(HXL), TSKguardcolumn, and the like can be mentioned as a combination.

As a typical example of the nitrogen-containing vinyl monomer,
For example, p-dimethylaminostyrene, dimethylaminomethyl acrylate, dimethylaminoethyl acrylate, dimethylaminopropyl acrylate, diethylaminomethyl acrylate, diethylaminoethyl acrylate, dimethylaminomethyl methacrylate, dimethylaminomethyl methacrylate, dimethylaminopropyl methacrylate, diethylaminomethyl methacrylate, Such as diethylaminoethylmethacrylate,
Further, nitrogen-containing heterocyclic N-vinyl compounds such as N-vinylimidazole, N-vinylbenzimidazole, N-vinylcarbazole, N-vinylpyrrole, N-vinylpiperidine, N-vinylmorpholine and N-vinylindole. Is mentioned.

Particularly, a nitrogen-containing vinyl monomer represented by the following general formula (1) such as dimethylaminoethyl methacrylate or diethylaminoethyl methacrylate, or 4
It is preferable to use a vinyl monomer containing a quaternary ammonium salt group. [However, R _{1 to} R ₄ represent a hydrogen atom or a saturated hydrocarbon group having 1 to 4 carbon atoms, and n represents an integer of 1 to 4. ]

The structure of the quaternary ammonium salt group-containing vinyl monomer used in the present invention is not particularly limited as long as it is copolymerizable with methyl methacrylate, but a more preferable quaternary ammonium salt group-containing vinyl monomer. Is a vinyl monomer containing a quaternary ammonium salt group represented by the following general formula (2). [In the formula, R ₅ represents a hydrogen atom or a methyl group, and R _5
6 represents an alkylene group having 1 to 4 carbon atoms, R _{7 to} R
₉ represents a methyl group, an ethyl group or a propyl group, and X ₁
Represents -COO- or -CONH-, and A ^- is C
Anions such as 1 ⁻ and (1/2) SO ₄ ²⁻ are shown. ]

In the present invention, the copolymer containing the vinyl polymerizable monomer and the nitrogen-containing vinyl monomer may be used alone or may be added to another binder resin. When used by being added to other binder resins, generally known resins as described above can be used. A thermosetting resin is more preferable in consideration of the mechanical strength required for the developer carrying member, but a thermoplastic resin can also be applied as long as it has sufficient mechanical strength.

Further, such a resin can be used as a charge control agent,
It may be used by blending it with a thermosetting resin having a higher strength than this. Even in such a case, the positive chargeability of the sleeve is improved due to the effect caused by the nitrogen-containing vinyl monomer.

Next, a nitrogen-containing heterocyclic compound will be described as another nitrogen-containing compound used in the conductive coating layer coated on the surface of the substrate constituting the developer carrier of the present invention.
The nitrogen-containing heterocyclic compound also improves the positive charging property of the coating layer and makes the carrier and the toner triboelectrically charged in the same manner as the above-mentioned copolymer.

The above nitrogen-containing heterocyclic compound has a number average particle size of preferably 20 μm or less, more preferably 0.1 to 0.5 μm.
It is preferable to use the one having a thickness of 15 μm. When the number average particle diameter of the nitrogen-containing heterocyclic compound exceeds 20 μm, it is difficult to obtain a sufficient effect of improving charging performance due to poor dispersibility of the nitrogen-containing heterocyclic compound in the resin coating layer, which is not preferable. Of course, when the nitrogen-containing heterocyclic compound is soluble in the coating composition, it is more preferable that it can be uniformly dispersed in the coating layer.

Examples of the nitrogen-containing heterocyclic compound used in the present invention include imidazole, imidazoline, imidazolone, pyrazoline, pyrazole, pyrazolone, oxazoline, oxazole, oxazolone, thiazoline, thiazole,
Thiazolone, selenazoline, selenazole, selenazolone, oxadiazole, thiadiazole, tetrazole, benzimidazole, benzotriazole, benzoxazole, benzothiazole, benzoselenazole, pyrazine, pyrimidine, pyridazine, triazine,
Nitrogen-containing heterocycles such as oxazine, thiazine, tetrazine, polyazine, pyridazine, pyrimidine, pyrazine, indole, isoindole, indazole, carbazole, quinoline, pyridine, isoquinoline, cinnoline, quinazoline, quinaxaline, phthalazine, purine, pyrrole, triazole, phenazine. The compound which has a group is mentioned. In the present invention, an imidazole compound is particularly preferred because of its high charging effect.

Particularly, among the imidazole compounds, the imidazole compound represented by the following general formula (3) or (4) is more preferable in terms of rapid and uniform charging property of the toner and strength of the coating layer. [In the formula, R ₁₀ and R ₁₁ represent a hydrogen atom, an alkyl group, an aralkyl group or an aryl group, and R ₁₀ and R ₁₁ may be the same or different. R ₁₂ and R ₁₃ represent a linear alkyl group having 3 to 30 carbon atoms, and R ₁₂ and R ₁₃ may be the same. ]

[0056] [In the formula, R ₁₄ and R ₁₅ represent a hydrogen atom, an alkyl group, an aralkyl group or an aryl group, and R ₁₄ and R ₁₅ may be the same. R ₁₆ represents a linear alkyl group having 3 to 30 carbon atoms. ] The imidazole compound represented by the following is more preferable from the viewpoints of rapid and uniform chargeability of the toner and strength of the coating layer.

The reason is that the imidazole compound having the structure represented by the general formula (3) or (4) has a linear alkyl group having 3 to 30 carbon atoms as a substituent.
It is considered that this is because the dispersibility of the coating layer with respect to the resin is good, and the triboelectrification property with the toner having a special dispersion state on the surface used in the present invention is good.

The nitrogen-containing heterocyclic group constituting the above-mentioned nitrogen-containing heterocyclic compound may be a monocyclic ring, may be condensed with another group, and may be substituted.

When the nitrogen-containing heterocyclic group is substituted, examples of the substituent include an alkyl group, an aralkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an aryl group, a substituted amino group, a ureido group and urethane. Group, aryloxy group, sulfamoyl group, carbamoyl group, alkyl or arylthio group, alkyl or arylsulfonyl group, alkyl or arylsulfinyl group, hydroxy group, halogen atom, cyano group, sulfo group, aryloxycarbonyl group, acyl group, alkoxy Carbonyl group, acyloxy group, carbonamido group,
Examples thereof include sulfonamide group, carbosyl group, phosphoric acid amide group, diacylamino group, and imide group.
The above substituents may further have a substituent. As examples of the substituent, the substituents described above as the substituent of the nitrogen-containing heterocycle can be used.

The content of the nitrogen-containing heterocyclic compound dispersed in the conductive coating layer is preferably 0.5 to 60 parts by mass, more preferably 1 to 50 parts by mass with respect to 100 parts by mass of the binder resin. A range of parts gives particularly favorable results. When the content of the nitrogen-containing heterocyclic compound is less than 0.5 parts by mass, the effect of imparting charge by the addition of the nitrogen-containing heterocyclic compound is small, and when it exceeds 60 parts by mass, the volume resistance of the conductive coating layer is reduced. It becomes difficult to control to a low level, and the effect of imparting charge is saturated, so the amount is excessive.

In the present invention, solid particles are added in order to suitably convey the developer to the developing area and to impart appropriate roughness to the developer carrier without mechanical treatment such as blasting. Good. Particularly, spherical particles are effective because they can form a suitable surface roughness with a small addition amount.

As the spherical particles used in the present invention, known spherical particles can be used. For example, there are spherical resin particles, spherical metal oxide particles, spherical carbonized particles, and the like.
As the spherical particles, for example, spherical resin particles produced by suspension polymerization, dispersion polymerization, or the like are used. Spherical resin particles, suitable surface roughness can be obtained with a smaller amount added,
Further, it is easy to obtain a uniform surface shape. Examples of such spherical particles include acrylic resin particles such as polyacrylate and polymethacrylate, polyamide resin particles such as nylon, polyolefin resin particles such as polyethylene and polypropylene, silicone resin particles, phenol resin particles, polyurethane particles. Examples thereof include resin particles, styrene resin particles, and benzoguanamine particles. The resin particles obtained by the pulverization method may be thermally or physically spheroidized before use.

Inorganic substances may be attached or fixed to the surface of the spherical particles. Such inorganic fine powders include SiO ₂ , SrTiO ₃ , CeO ₂ ,
Oxides such as CrO, Ai ₂ O ₃ , ZnO and MgO, Si
Nitride such as ₃ N ₄ , carbide such as SiC, CaSO ₄ ,
Examples thereof include carbides such as BaSO ₄ and CaCO ₃ , carbonates and the like. Such inorganic fine powder may be treated with a coupling agent before use.

Particularly, a coupling agent can be preferably used for the purpose of improving the adhesion with the binder resin or for the purpose of imparting hydrophobicity to the particles. Examples of such a coupling agent include a silane coupling agent, a titanium coupling agent, and a zircoaluminate coupling agent. More specifically, for example, as the silane coupling agent, hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane. , Benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilylmercaptan, trimethylsilylmercaptan, triorganosilylacrylate, vinyldimethylacetoxysilane, Dimethyldiethoxysilane, dimethyldimethoxysilane, diphenyldiethoxysilane,
Hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane and silicon having 2 to 12 siloxane units per molecule, one for each terminally located unit Examples thereof include dimethylpolysiloxane containing a hydroxyl group bonded to an atom.

By treating the surface of the spherical resin particles with the inorganic fine powder as described above, the dispersibility in the coating layer, the uniformity of the coating layer surface, the stain resistance of the coating layer, and the charge imparting property to the toner. The wear resistance of the coating layer can be improved.

Further, conductive spherical particles are more preferable because they give less improper triboelectric charge to the developer and do not hinder the charge imparting property of the resin. In addition, the conductive spherical particles further enhance the effect of the charge control agent by interaction with the charge control agent contained in the coating layer, further improve quick and uniform charging, and further stabilize the charging performance. There is also an effect.

The electrically conductive spherical particles used in the present invention have a number average particle size of 0.3 to 30 μm, preferably 2 to
It is preferable that the thickness is 20 μm and the true density is 3 g / cm ³ or less. When the number average particle diameter of the conductive spherical particles is less than 0.3 μm, the effect of imparting uniform roughness to the surface and the effect of enhancing the charging performance are small, and rapid and uniform charging of the developer becomes insufficient. However, it is not preferable because charge-up of the developer due to abrasion of the coating layer, developer contamination and fusion of the developer are likely to occur, and sharpness of character lines of the obtained image and reduction in image density are likely to occur. If the number average particle diameter exceeds 30 μm, the roughness of the surface of the coating layer becomes too large, which makes it difficult to sufficiently charge the developer and reduces the mechanical strength of the coating layer. Not preferable.

The true density of the conductive spherical particles used in the present invention is 3 g / cm ³ or less, preferably 2.7 g / c.
m ³ or less, more preferably 0.9 to 2.3 g / cm ³ . That is, the true density of the conductive spherical particles is 3
If it exceeds g / cm ³ , the dispersibility of the spherical particles in the coating layer will be insufficient, and it will be difficult to impart uniform roughness to the surface of the coating layer, and the charge control agent will also be dispersed uniformly. This is not preferable, because the developer is not rapidly charged and the developer is rapidly and uniformly charged and the strength of the coating layer becomes insufficient.

In the present invention, the electrically conductive spherical particles have a volume resistivity of 10 ⁶ Ω · cm or less, preferably particles having a volume resistance of 10 ³ to 10 ⁻⁶ Ω · cm. To do. Volume resistance of conductive spherical particles is 10 ⁶ Ω
If it exceeds cm, the spherical particles exposed on the surface of the conductive coating layer due to abrasion are likely to cause contamination or fusion of the developer, and it is difficult to perform rapid and uniform charging, which is not preferable.

The term "spherical" in the conductive spherical particles means that the ratio of major axis / minor axis of the particles is about 1.0 to 1.5, and in the present invention, the ratio of major axis / minor axis is preferably. It is preferable to use particles of 1.0 to 1.2. When the ratio of the major axis / minor axis of the conductive spherical particles exceeds 1.5, the dispersibility of the conductive spherical particles in the coating layer decreases and the dispersibility of the charge control agent in the coating layer also decreases. Also, the surface roughness of the coating layer becomes non-uniform, which is not preferable in terms of rapid and uniform charging of the developer and strength of the conductive coating layer.

As a method for obtaining the conductive spherical particles used in the present invention, the following methods are preferable, but not limited to these methods.

As a method for obtaining the particularly preferred conductive spherical particles used in the present invention, for example, resin-based spherical particles or mesocarbon microbeads are calcined and / or carbonized.
Another example is a method of obtaining low-density and highly conductive spherical carbon particles obtained by graphitization. And as the resin used for the resin-based spherical particles, for example, phenol resin, naphthalene resin, furan resin, xylene resin, divinylbenzene polymer, styrene-divinylbenzene copolymer,
Examples include polyacrylonitrile.

The mesocarbon microbeads can be usually produced by washing spherical crystals produced in the process of heating and firing the medium pitch with a large amount of a solvent such as tar, medium oil and quinoline.

As a more preferable method for obtaining conductive spherical particles, a spherical resin particle surface such as phenol resin, naphthalene resin, furan resin, xylene resin, divinylbenzene polymer, styrene-divinylbenzene copolymer, polyacrylonitrile, Bulk mesophase pitch is coated by a mechanochemical method, and the coated particles are heat treated in an oxidizing atmosphere and then fired in an inert atmosphere or in a vacuum to carbonize and / or graphitize to obtain conductive spherical carbon particles. There is a method. The spherical carbon particles obtained by this method are more preferable because the graphitization makes the coated portion of the spherical carbon particles obtained have advanced crystallization, thereby improving the conductivity.

In any of the conductive spherical carbon particles obtained by the above-mentioned method, the conductivity of the obtained spherical carbon particles can be controlled to some extent by changing the firing conditions. Is preferably used in. Further, the spherical carbon particles obtained by the above method,
In some cases, conductive metal and / or metal oxide may be plated within the range in which the true density of the conductive spherical particles does not exceed ³ g / cm ³ in order to further increase the conductivity.

As another method for obtaining the conductive spherical particles used in the present invention, the conductive fine particles smaller than the particle diameter of the core particles are mechanically mixed with the core particles composed of the spherical resin particles at an appropriate mixing ratio. When the conductive fine particles are uniformly attached to the periphery of the core particles by the action of Van der Waals force and electrostatic force, the core is heated by a local temperature rise caused by applying mechanical impact force. Examples include a method of softening the particle surface and forming conductive fine particles on the surface of the core particle to obtain conductive resin-treated spherical resin particles.

For the core particles, it is preferable to use spherical resin particles of an organic compound having a small true density. Examples of the resin include PMMA, acrylic resin,
Examples thereof include polybutadiene resin, polystyrene resin, polyethylene, polypropylene, polybutadiene, or copolymers thereof, benzoguanamine resin, phenol resin, polyamide resin, nylon, fluorine resin, silicone resin, epoxy resin, polyester resin and the like. As the conductive fine particles (small particles) used when forming a film on the surface of the core particles (mother particles), in order to uniformly provide the conductive fine particle coating, the particle size of the small particles is smaller than that of the mother particles. 1
It is preferable to use / 8 or less.

As still another method for obtaining the conductive spherical particles used in the present invention, the conductive spherical particles in which the conductive fine particles are dispersed by uniformly dispersing the conductive fine particles in the spherical resin particles are provided. The method of obtaining. As a method for uniformly dispersing the conductive fine particles in the spherical resin particles, for example, the binder resin and the conductive fine particles are kneaded to disperse the conductive fine particles, followed by cooling and solidification, and pulverization to a predetermined particle size. And to obtain conductive spherical particles by spheroidizing by mechanical and thermal treatments; or adding a polymerization initiator, conductive fine particles and other additives to the polymerizable monomer,
The monomer composition uniformly dispersed by a disperser is suspended in an aqueous phase containing a dispersion stabilizer so as to have a predetermined particle diameter by a stirrer or the like, and polymerization is performed to disperse the conductive fine particles. The method of obtaining the spherical particles thus obtained can be mentioned.

The conductive spherical particles in which the conductive fine particles obtained by these methods are dispersed are mechanically mixed with the conductive fine particles having a particle size smaller than the core particles described above at an appropriate mixing ratio to obtain a van der After the conductive fine particles are uniformly attached to the periphery of the conductive spherical particles by the action of the Warls force and the electrostatic force, for example, the surface of the conductive spherical particles is caused by a local temperature rise caused by applying a mechanical impact force. May be softened, conductive fine particles may be formed into a film on the surface, and the conductivity may be further increased before use.

The surface roughness of the coating layer on the surface of the developer carrying member having the above-mentioned constitution which is preferably used in the present invention is J
The IS center line average roughness (Ra) is preferably in the range of 0.1 to 5.0 μm. More preferably 0.3-
It is 3.0 μm. That is, when Ra is less than 0.1 μm, the transportability of the developer on the developer carrying member to the developing area is poor, and it becomes difficult to obtain a sufficient image density. On the other hand, when Ra exceeds 5.0 μm, unevenness occurs in the developer layer formed on the developer carrying member, which causes density unevenness on the image.

Next, the methods for measuring the physical properties of the developer carrying member of the present invention will be described. (1) Measurement of center line average roughness (Ra) Based on the surface roughness of JIS B0601, a surf coder SE-3300 manufactured by Kosaka Laboratory was used to measure 3 points in the axial direction × 2 points in the circumferential direction = 6 points, respectively. , And took the average value.

(2) Measurement of volume resistance of particles A granular sample was placed in an aluminum ring of 40 mmφ and 2500
Pressure molding is performed with N, and the volume resistance value is measured with a four-terminal probe using a resistivity meter Lorester AP or Hiresta IP (both manufactured by Mitsubishi Yuka). The measurement environment is 20
-25 ° C and 50-60% RH.

(3) Measurement of Volume Resistance of Coating Layer A coating layer having a thickness of 7 to 20 μm was formed on a PET sheet having a thickness of 100 μm, and the standard ASTM (D-991-8) was used.
2) and Japan Rubber Association standard SRIS (2301-
1969), using a voltage drop type digital ohmmeter (manufactured by Kawaguchi Denki Seisakusho) provided with electrodes having a four-terminal structure for measuring the volume resistance of conductive rubber and plastic. The measurement environment is 20 to 25 ° C and 50 to 60R.
H%.

(4) Measurement of True Density of Spherical Particles The true density of the conductive spherical particles used in the present invention was measured using a dry densitometer Accupic 1330 (manufactured by Shimadzu Corporation).

(5) Particle Size Measurement of Spherical Particles The particle size is measured using a Coulter LS-230 type particle size distribution meter (manufactured by Coulter), which is a laser diffraction type particle size distribution meter. An aqueous module is used as the measuring method, and pure water is used as the measuring solvent. The measurement system of the particle size distribution meter is washed with pure water for about 5 minutes, 10 to 25 mg of sodium sulfite is added to the measurement system as an antifoaming agent, and the background function is executed. Next, the surfactant 3 was added to 10 ml of pure water.
Add ~ 4 drops and add 5-25 mg of measurement sample.
The aqueous solution in which the sample is suspended is dispersed by an ultrasonic disperser for about 1 to 3 minutes to obtain a sample solution, and the sample solution is gradually added into the measurement system of the above-mentioned measuring device. Four
The concentration of the sample in the measurement system is adjusted so as to be 5 to 55%, the measurement is performed, and the number average particle diameter calculated from the number distribution is obtained.

(6) Measurement of Triboelectric Charge Amount of Developer on Developer Carrier FIG. 3 is a schematic view of the charge amount measuring device. Using this device, the suction port 31 is pressed against the recording material to suck the developer,
Collect in the filter 32 of the inner cylinder. At this time, the inner cylinder is electrostatically shielded from the outside, the charge amount of the developer accumulated therein is increased by the Faraday gauge 33 connected thereto, and the mass of the sucked developer is increased by the mass of the filter. The charge amount of the developer on the developer carrying member (charge amount per unit mass) is calculated from this.

The developer used in the present invention will be described below. The carrier particles used in the present invention are those having a resin component on at least the surface thereof. For example, iron, copper, nickel, magnetic metals such as cobalt, magnetite, resin coating on the core material of magnetic oxide such as ferrite. A layered product or a magnetic material-dispersed carrier in which the above-described magnetic material fine particles are dispersed in a resin can be used.

The binder resin used for the core material in the constitution of the magnetic substance dispersion type carrier used in the present invention is as follows.
All resins obtained by polymerizing vinyl monomers are mentioned. Examples of the vinyl-based monomer here include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-phenylstyrene, p-
Ethylstyrene, 2,4-dimethylstyrene, pn-
Butyl styrene, p-tert-butyl styrene, p-
n-hexyl styrene, pn-octyl styrene, p
-N-nonylstyrene, pn-decylstyrene, p-
Styrene derivatives such as n-dodecylstyrene, p-methoxystyrene, p-chlorostyrene, 3,4-dichlorostyrene, m-nitrostyrene, o-nitrostyrene, p-nitrostyrene, and ethylene, propylene, butylene, isobutylene Ethylene and unsaturated monoolefins such as; unsaturated diolefins such as butadiene and isoprene; vinyl chloride, vinylidene chloride, vinyl bromide,
Vinyl halides such as vinyl fluoride; vinyl acetate,
Vinyl esters such as vinyl propionate and vinyl benzoate; methacrylic acid and methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, methacrylic acid. −
Α-Methylene aliphatic monocarboxylic acid esters such as 2-ethylhexyl, stearyl methacrylate, phenyl methacrylate; acrylic acid and methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, acrylic Acrylic esters such as n-octyl acid, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate;
Maleic acid, maleic acid half ester; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether; vinyl methyl ketone,
Vinyl ketones such as vinyl hexyl ketone and methyl isopropenyl ketone; N-vinyl compounds such as N-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole and N-vinyl pyrrolidone; vinyl naphthalenes;
Examples thereof include acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide; acrolein, and the like. One of these or two or more of them is used for polymerization.

In addition to resins obtained by polymerizing vinyl monomers, non-vinyl condensation resins such as polyester resins, epoxy resins, phenol resins, urea resins, polyurethane resins, polyimide resins, cellulose resins and polyether resins, or these resins. And a mixture of the above vinyl-based resin can be used.

As the magnetic fine particles constituting the magnetic substance dispersion type carrier used in the present invention, for example, ferromagnetic metals such as iron, cobalt and nickel, ferrite, magnetite and hematite, and ferromagnetism such as iron, cobalt and nickel are shown. Examples include alloys or compounds containing elements.

The magnetic fine particles preferably have a primary average particle diameter of 2.0 μm or less. When it is larger than 2.0 μm, the surface of the core material is not dense and uniform coating cannot be performed. Furthermore, it is necessary that the magnetic fine particles according to the present invention have a specific resistance of 10 ⁹ Ω · cm or less and a content of 30% by mass or more, preferably 50% by mass or more based on the total amount of carriers. If it is less than 30% by mass, adhesion to the photoconductor (image bearing member) occurs, and it becomes difficult to control the resistance of the carrier.

Of course, even in the magnetic substance-dispersed carrier itself used in the present invention, it is one of the important characteristics that it is possible to control the charge amount of the toner, which does not cause the toner to adhere to the photosensitive member. It is preferable to appropriately control the specific resistance of the carrier so as not to cause a so-called charge-up phenomenon, which is the excessive charging of the toner below. Therefore, in the carrier of the present invention, it is preferable that the particle diameter, the specific resistance and the content of the magnetic fine particles as described above are set.

The average particle size of the magnetic substance-dispersed carrier used in the present invention is preferably in the range of 10 to 60 μm. If it is smaller than 10 μm, the carrier easily adheres to the photoconductor, causing scratches on the photoconductor, which causes image deterioration. On the other hand, when it exceeds 60 μm, the share of the developer in the developing device becomes large, and the deterioration of the developer,
In particular, the external additive of the toner particles may be peeled off or the shape of the toner particles may be changed to cause image deterioration. Furthermore, if the particle size is large, the specific surface area becomes small, so that the amount of toner that can be held in constituting the developer becomes small, and the image lacks fineness.

The true specific gravity of the magnetic substance-dispersed carrier used in the present invention is preferably in the range of 1.5 to 5.0.
It is more preferably 1.5 to 4.5. When the true specific gravity exceeds 5.0, the share of the developer in the developing device becomes large, which is not preferable from the viewpoint of deterioration of the developer. If the true specific gravity is less than 1.5, it is practically impossible to obtain a magnetic force sufficient to suppress carrier adhesion to the photoconductor.

The specific resistance of the carrier used in the present invention is 1
The range of 0 ⁷ to 10 ¹⁵ Ω · cm is suitable. 10 ⁷ Ω · c
If it is less than m, in the developing method in which a bias voltage is applied, a current leaks from the sleeve to the surface of the photoconductor in the developing area, and a good image cannot be obtained. On the other hand, if it exceeds 10 ¹⁵ Ω · cm, a charge-up phenomenon is caused under a condition such as low humidity, which causes image deterioration such as density distortion, transfer failure, and fog.

The sphericity (major axis / minor axis) of the magnetic material-dispersed carrier of the present invention is preferably 2 or less. If the sphericity exceeds 2, the effect of reducing the share of the developer and the effect of improving the fluidity of the developer tend to be reduced. Therefore, the sphericity is preferably 2 or less in order to prevent the effects of preventing the deterioration of the developer and improving the developing characteristics that can be achieved by the carrier in the present invention.

As means for achieving the above-mentioned sphericity of 2 or less in the magnetic substance dispersion type carrier in the present invention, there is a method of heating the core material to heat-melt the surface to make it spherical, or a method of making it mechanically spherical. is there. Alternatively, the core material can be produced by adding magnetic fine particles, a polymerization initiator, a suspension stabilizer, etc. to a monomer solution of a binder resin used for the core material and dispersing them, and then granulating and polymerizing the core material. If a usual suspension polymerization method for obtaining the above is used, the sphericity of 2 or less of the carrier can be achieved without treating the core material.

The toner used in the present invention may be either toner particles produced by a pulverizing method or a polymerization method, but toner particles produced by a polymerization method, particularly a suspension polymerization method are preferably used. To be Also,
A seed polymerization method in which a monomer is further adsorbed to the polymer particles once obtained and then polymerized by using a polymerization initiator can also be suitably used in the present invention.

In the production of toner particles by the pulverization method, constituent materials such as a binder resin, a colorant and a charge control agent are thoroughly mixed by a ball mill or other mixer, and then a heat kneader such as a heat roll kneader or an extruder is used. Well kneaded, and solidified by cooling, and then mechanically pulverized and classified to obtain toner particles. Further, it is more preferable to use toner particles that have been subjected to spheroidizing treatment by applying hot air treatment or mechanical impact after classification.

Next, an example of the image forming apparatus of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of an example of an image forming apparatus according to the present invention. Reference numeral 1 denotes a rotary drum type electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) as an image bearing member. This photosensitive drum 1 has an aluminum cylinder (conductive drum base) 1a as shown in the layer structure schematic diagram of FIG.
On the surface of the undercoat layer 1b, which suppresses light interference and improves the adhesiveness of the upper layer, the photocharge generation layer 1c, and the charge transport layer 1d.
The above three layers are applied in order from the bottom.

Reference numeral 2 is a contact charging device (contact charging device) as a charging means for uniformly charging the peripheral surface of the photosensitive drum 1, and this example is a charging roller (roller charging device). The charging roller 2 rotatably holds both ends of a cored bar 2a by bearing members (not shown), and biases the cored bar 2a toward the photosensitive drum by a pressing spring 2e so that the charging roller 2 has a predetermined surface relative to the surface of the photosensitive drum 1. They are pressed against each other with a pressing force, and are rotated by the rotation of the photosensitive drum 1. The pressure contact portion between the photosensitive drum 1 and the charging roller 2 is a charging portion (charging nib portion) a.

By applying a charging bias voltage of a predetermined condition from the power source S1 to the core metal 2a of the charging roller 2, the peripheral surface of the rotary photosensitive drum 1 is contact-charged to a predetermined polarity and potential. In this example, the charging bias voltage for the charging roller 2 is a DC voltage (Vdc) and an AC voltage (V
ac) is an oscillating voltage that is superimposed.

The longitudinal length of the charging roller 2 is 320 mm, and the core metal (support member) 2 is provided as shown in the layer structure schematic diagram of FIG.
It has a three-layer structure in which a lower layer 2b, an intermediate layer 2c and a surface layer 2d are sequentially laminated from the bottom around the outer periphery of a. The lower layer 2b is a foam sponge layer for reducing charging noise, and the intermediate layer 2c
Is a conductive layer for obtaining uniform resistance as a whole of the charging roller, and the surface layer 2d is a protective layer provided to prevent leakage even if there is a defect such as a pinhole on the photosensitive drum 1. is there.

In FIG. 2, 2f is a charging roller cleaning member, which is a flexible cleaning film in this example. The cleaning film 2f is arranged parallel to the longitudinal direction of the charging roller 2 and has one end fixed to a supporting member 2g which reciprocates a certain amount in the longitudinal direction, and the charging roller 2 is provided on the surface near the free end side. And is arranged to form a contact nip with. Support member 2g
Is driven by a drive motor of the printer through a gear train in a reciprocating motion in the longitudinal direction by a constant amount, and the charging roller surface layer 2
d is rubbed with the cleaning film 2f. As a result, contaminants (fine powder toner, external additives, etc.) attached to the surface layer 2d of the charging roller are removed.

Reference numeral 3 denotes an exposure device as an information writing means for forming an electrostatic latent image on the surface of the photosensitive drum 1 which has been subjected to the charging process, and this example is a laser beam scanner. A laser beam L modulated in accordance with an image signal sent from a host device such as an image reading device (not shown) to the printer side is output to perform laser scanning on the uniformly charged surface of the rotating photosensitive drum 1 at the exposure position b. Expose. Due to this laser scanning exposure, the potential of the surface of the photosensitive drum 1 irradiated with the laser beam L is lowered, so that electrostatic latent images corresponding to the image information subjected to the scanning exposure are sequentially formed on the surface of the rotating photosensitive drum 1. Go.

Reference numeral 4 denotes a developing device (developing device) as a developing means for supplying a developer (toner) to the electrostatic latent image on the photosensitive drum 1 to visualize the electrostatic latent image. In this example, a two-component magnetic brush is used. It is a developing type reversal developing device.

Reference numeral 4a is a developing container, and 4b is a developing sleeve, which is usually made of a metal cylinder such as aluminum and its alloys and stainless steel. However, the metal may be any as long as it can be easily formed into a cylinder. It is not particularly limited. The developing sleeve 4b is rotatably disposed in the developing container 4a by exposing a part of the outer peripheral surface thereof to the outside. Reference numeral 4c designates a magnet roller fixed in a non-rotating manner and inserted in the developing sleeve 4b, 4d designates a developer coating blade, 4e.
Is a two-component developer housed in the developing container 4a, 4f is a developer stirring member disposed on the bottom side in the developing container 4a, 4g is a toner hopper, and contains replenishment toner.

The two-component developer 4e in the developing container 4a is a mixture of toner and magnetic carrier and is stirred by the developer stirring member 4f. The toner is basically the developer stirring material 4
By the stirring of f, the negative charge is triboelectrically charged by the rubbing against the magnetic carrier. Further, the toner existing in the vicinity of the developing sleeve 4b is also triboelectrically charged by sliding friction with the developing sleeve 4b. The above-described coating layer is formed on the surface of the developing sleeve 4b, and the toner is triboelectrically charged to have a normal polarity, in this example, a negative polarity.

The developing sleeve 4b is arranged facing the photosensitive drum 1 so that the closest distance (referred to as S-Dgap) to the photosensitive drum 1 is kept at 350 μm and is close to the photosensitive drum 1. The facing portion between the photosensitive drum 1 and the developing sleeve 4b is the developing portion c. The developing sleeve 4b is connected to the photosensitive drum 1 in the developing section c.
Is rotationally driven in the direction opposite to the traveling direction. On the outer peripheral surface of the developing sleeve 4b, the magnet roller 4 in the sleeve is formed.
A part of the two-component developer 4e in the developing container 4a is adsorbed and held as a magnetic brush layer by the magnetic force of c, and is rotatably conveyed as the sleeve rotates, and the developer coating blade 4d.
By this, a predetermined thin layer is formed, and the surface of the photosensitive drum 1 is brought into contact with the developing portion c and the surface of the photosensitive drum is appropriately rubbed.

A predetermined developing bias is applied to the developing sleeve 4b from the power source S2. In this example, the developing bias voltage for the developing sleeve 4b is a direct current voltage (Vdc).
And an alternating voltage (Vac) are superposed on each other. Thus, the toner in the developer, which is coated as a thin layer on the surface of the rotating developing sleeve 4b and is conveyed to the developing section c, corresponds to the electrostatic latent image on the surface of the photosensitive drum 1 by the electric field due to the developing bias. By selectively adhering, the electrostatic latent image is developed as a toner image. In the case of this example, toner adheres to the exposed bright portion of the surface of the photosensitive drum 1 and the electrostatic latent image is reversely developed.

The thin developer layer on the developing sleeve 4b which has passed through the developing portion c is returned to the developer reservoir portion in the developing container 4a as the developing sleeve continues to rotate. In order to maintain the toner concentration of the two-component developer 4e in the developing container 4a within a predetermined substantially constant range, the two-component developer 4e in the developing container 4a is
Is detected by, for example, an optical toner concentration sensor (not shown), and the toner hopper 4g is drive-controlled in accordance with the detection information so that the toner in the toner hopper 4g becomes the two-component developer 4e in the developing container 4a. Will be replenished. The toner supplied to the two-component developer 4e is agitating member 4
Stirred by f.

A transfer device 5 is a transfer roller in this example. The transfer roller 5 is brought into pressure contact with the photosensitive drum 1 with a predetermined pressing force, and the pressure contact nib portion is the transfer portion d.
Is. A transfer material (transferred member, recording material) P is fed to the transfer section d from a paper feed mechanism section (not shown) at a predetermined control timing.

The transfer material P fed to the transfer portion d is nipped and conveyed between the rotating photosensitive drum 1 and the transfer roller 5, and during that time, the transfer roller 5 is supplied from the power source S3 to the negative electrode having the normal charging polarity of the toner. By applying a transfer bias of positive polarity having a polarity opposite to that of the transfer property, the toner images on the surface of the photosensitive drum 1 are sequentially electrostatically transferred to the surface of the transfer material P which is nipped and conveyed at the transfer portion d. To go.

The transfer material P which has received the transfer of the toner image through the transfer portion d is sequentially separated from the surface of the rotary photosensitive drum 1 and conveyed to the fixing device 6 (for example, a heat roller fixing device) to fix the toner image. Image formation (print,
Output as a copy).

Reference numeral 7 denotes a toner charging control means, which is a brush-shaped member having an appropriate conductivity, and is arranged with the brush portion in contact with the surface of the photosensitive drum 1. The power source S4 has a negative voltage. Is being applied more. Reference numeral e is a contact portion between the brush portion and the surface of the photosensitive drum 1. By aligning the charge polarity of the transfer residual toner to the negative polarity that is the normal polarity, when the surface of the photosensitive drum 1 is charged from above the transfer residual toner by the charging portion a located further downstream, By increasing the mirroring power to 1, the transfer residual toner is prevented from adhering to the charging roller 2. Adhesion of toner to the charging roller 2 causes a defective charging image. The toner that has passed through the charging roller 2 and has been discharged is weakened in the mirroring force on the photosensitive drum 1, is adsorbed and held by the above-mentioned magnetic brush layer in the developing section c, and is rotatively conveyed and collected as the developing sleeve rotates. It

[0116]

EXAMPLES Next, the present invention will be specifically described with reference to practical examples and comparative examples. <Example 1>

As the spherical particles, the number average particle diameter is 7.8 μm.
A number average particle diameter of 2 μm is applied to 100 parts by mass of the spherical phenol resin particles of No. 3 by using a Laikai machine (automatic mortar, manufactured by Ishikawa Factory)
14 parts by mass of the following coal-based bulk mesophase pitch powder are uniformly coated, heat-stabilized in air at 280 ° C., and then graphitized by firing at 2,000 ° C. in a nitrogen atmosphere, and further classified. Number average particle size 11.7
The spherical conductive carbon particles (spherical particles C-1) having a size of μm were used. Table 1 shows the physical properties of the spherical particles C-1.

The above material (spherical particles C-1) was subjected to sand mill dispersion with 2 mmφ zirconia particles for 3 hours, then the zirconia particles were separated by sieving and the solid content was adjusted to 40% by mass with MEK to prepare a coating solution ( c (carbon) / Gf (graphite) / B (phenolic resin) / D (copolymer A)
-1) / Z (charge control agent) / R (spherical particles) = 0.2 /
0.8 / 3 / 0.6 / 0 / 0.7) was obtained. This coating liquid is coated on an insulating sheet with a bar coater and dried,
This was cut into a standard shape and measured with a low resistivity meter, Lorester (manufactured by Mitsubishi Chemical Co., Ltd.), and the volume resistivity was 40.2Ω.
・ It was cm.

This paint was sprayed to give an A of 20 mmφ.
A film having a thickness of 15 μm was formed on a cylindrical body, and then heated and cured at 150 ° C./30 minutes with a hot air drier to prepare a developer carrying body D-1. Ra on the surface of the conductive coating layer on the developer carrying member was measured at 6 points with a surf coder SE-3300 (manufactured by Kosaka Laboratory) at an evaluation length of 4 mm, and the average value was calculated. Ra = 1. It was 93 μm.

(Production of Magnetic Material Dispersed Carrier) Phenol / formaldehyde monomer (50: 5) in an aqueous medium.
0) were mixed and dispersed, and then 600 parts by mass of 0.25 μm magnetite particles and 0.6 μm hematite particles 4 surface-treated with a titanium coupling agent with respect to the mass of the monomer.
00 parts by mass are uniformly dispersed, the monomer is polymerized while appropriately adding ammonia, and a magnetic particle-encapsulated spherical magnetic resin carrier core material (average particle size 33 μm, saturation magnetization 38 Am ² /
kg) was obtained.

On the other hand, 20 parts by mass of toluene and 2 parts of butanol
Four-mass frass with 0 parts by mass, 20 parts by mass of water and 40 parts by mass of ice
CH, CH while stirring₃SiCl₃Is 15 mol,
(CH ₃)₂SiCl₂40 parts by mass of a mixture with 10 mol
, Stir for another 30 minutes, and then shrink at 60 ° C for 1 hour.
A combined reaction was performed. Then wash the siloxane thoroughly with water
Mixed with toluene-methyl ethyl ketone-butanol
Dissolve in a medium and prepare a silicone varnish with a solid content of 10% by mass.
Made

Into this silicone varnish, 2.0 parts by mass of ion-exchanged water, 2.0 parts by mass of the following curing agent, 1.0 part by mass of the following aminosilane coupling agent) and 100 parts by mass of siloxane solid content), 5.0 parts by mass of the following silane coupling agent was simultaneously added to prepare a carrier coating solution (i). This solution (i) was applied to the above-mentioned carrier core material 10 with a coating machine (Okada Seiko Co., Ltd .: Spiracoater).
It was applied to 0 parts by weight so that the resin coating amount was 1 part by weight to obtain a coated carrier (i). This carrier (i)
Has a 50% particle size of 33 μm and a volume resistance value of 4 × 1.
0 ¹³ Ω · cm and impedance of 2 × 10 ¹⁰ Ω ·
It was cm.

The triboelectric charge amount of the obtained coated carrier (i) with respect to the developer carrying member D-1 was measured as follows. Commercially available copying machine CP2100 (made by Canon)
The developing device of No. 1 was used to replace the developer carrying member with the above D-1, and the closest distance to the developer coating blade (S
-Bgap) was set to 300 μm. Then, 200 g of the carrier is filled in the developing device, and 23.5 ° C. and 60% R
After spinning for 1 minute under normal temperature and normal humidity (N / N) environment of H, the carrier on the developer carrier is sucked and collected by the metal cylindrical tube and the cylindrical filter, and at that time, it is collected in the condenser through the metal cylindrical tube. From the stored charge amount Q and the collected carrier mass M, the charge amount per unit mass Q / M (m
C / kg) was calculated and used as the triboelectric charge amount of the carrier. As a result of measurement by the above method, the triboelectric charge amount of the coated carrier (i) with respect to the developer carrying member D-1 was 0.000032 m.
It was C / kg.

(Production of Polymerized Toner) Ion-exchanged water 709
451 parts by mass of 0.1 M Na ₃ PO ₄ aqueous solution was added to the parts by mass, and the mixture was heated to 60 ° C. and then stirred at 6,000 rpm using a TK homomixer (manufactured by Tokushu Kika Kogyo).
67.7 parts by mass of 1.0 M-CaCl ₂ aqueous solution was gradually added to this to obtain a dispersion medium containing Ca ₃ (PO ₄ ) ₂ .

Of the above formulations, C.I. I. Pigment Blue 15: 3, di-tert-butylsalicylic acid metal compound and styrene only Ebara Milder (Ebara Corporation)
Was used for premixing. Next, add all of the above prescriptions to 60
The mixture was heated to ℃, dissolved and dispersed to obtain a monomer mixture. Further, while maintaining the temperature at 60 ° C., 10 parts by mass of an initiator dimethyl 2,2′-azobisisobutyrate was added and dissolved to prepare a monomer composition.

The above monomer composition was added to the dispersion medium prepared in the 10 liter flask of the homomixer.
The monomer composition was granulated by stirring at 60 ° C. for 20 minutes at 5,000 rpm using a TK homomixer in a nitrogen atmosphere. Then, the mixture was reacted at 60 ° C. for 3 hours while stirring with a paddle stirring blade, and then polymerized at 80 ° C. for 10 hours. After the completion of the polymerization reaction, the reaction product was cooled, hydrochloric acid was added, and Ca ₃
By dissolving (PO ₄ ) ₂ and filtering, washing with water and drying,
A polymerized toner was obtained.

The particle size of the obtained toner was measured with a Coulter counter to find that the weight average particle size was 8.2 μm and the particle size distribution was sharp. Furthermore, when the cross section of the particles was observed by a transmission electron microscope by a dyeing ultrathin section method, it was divided into a surface layer part mainly composed of styrene-acrylic resin and a central part mainly composed of wax, and a capsule structure could be confirmed. . To 100 parts by mass of the obtained toner,
0.7 parts by mass of hydrophobic silica having a specific surface area according to the BET method of 200 m ² / g was externally added. The magnetic material-dispersed carrier thus prepared and a cyan toner were mixed at a toner concentration of 8% by mass to prepare a cyan two-component developer.

Next, an image forming apparatus of a commercial copying machine CP2100 (manufactured by Canon Inc.) was modified as shown in FIG. 1, the developing sleeve was used, and the charging roller shown in FIG. 2 was used as a charging member. / AC electric field (-500V, 1kH
z / 1.4 kVpp) is applied in a superimposed manner, the photoconductor is charged, the cleaning unit is removed, the development contrast is set to 350 V, the reverse contrast to fogging is set to −150 V, and the development bias having a discontinuous AC electric field in FIG. 2 is set. Apply the cyan two-component developer described above
3.5 ℃, 10% RH, room temperature and low humidity (N / L), and 3
It was performed up to 30,000 sheets under a high temperature and high humidity (H / H) environment of 0.0 ° C. and 80% RH.

<Evaluation> (1) Image Density The image density of a φ5 black circle on a test chart with an image ratio of 5.5% was measured with a reflection densitometer RD918 (manufactured by Macbeth Co.) to examine the durability of the image density. .

(2) The reflectance of the fogged solid white image is measured, and the reflectance of the unused transfer paper is further measured. From the worst value of the reflectance of the solid white image to the maximum value of the reflectance of the unused transfer paper. The subtracted value was defined as the fog density. The reflectance was measured by TC-6DS (manufactured by Tokyo Denshoku Co., Ltd.). However, when visually observing the measured value, 1.5% or less is a level that can hardly be visually confirmed, 2.0 to 3.0.
% Is a level that can be confirmed by looking closely, and is a level where fogging can be confirmed at a glance if it exceeds 4.0%.

(3) Toner charge amount on sleeve (Q / M)
And toner transport amount (M / S) The toner carried on the developing sleeve was sucked and collected by the metal cylindrical tube and the cylindrical filter, and at that time, the amount of charge Q accumulated in the condenser was collected through the metal cylindrical tube. The charge amount Q / M (mC / kg) per unit mass and the toner mass M / S (dg / m ² ) per unit area are calculated from the toner mass M and the toner suction area S, and the toner charging The amount (Q / M) and the toner conveyance amount (M / S) were used.

(4) Blotches (spot images) Solid black images and halftone (HT) images are developed,
In each image, a blotch (spot image) that is likely to occur due to excessive charging of the toner was visually observed, and the evaluation results are shown by the following indexes. ⊚: No blotches are seen. ◯: A slight blotch is seen in the HT image. B: Blotches are slightly seen in the HT image, but at the lower limit of the practical level. △ ×: Blotches are also seen in solid black images, which is not practical. X: A noticeable blotch is also seen in a solid black image.

(5) Carrier-adhered solid white image is imaged, and a portion on the photosensitive drum between the developing section and the cleaner section is adhered with a transparent adhesive tape for sampling, and the sample is placed on the photosensitive drum within 5 cm × 5 cm. The number of magnetic carrier particles adhered to is counted and the number of adhered carrier particles per cm ² is calculated. A: Less than 5 ◯: 5 to less than 10 Δ: 10 to less than 20 pieces. X: 20 or more. The evaluation results are shown in Table 4 or 5. It was a good result.

<Example 2> Copolymer A used in Example 1
A developer carrying member D-2 was prepared in the same manner as in Example 1 except that the addition amount of -1 was 10 parts by mass, and the same evaluation as in Example 1 was performed.

Example 3 Copolymer A used in Example 1
A developer carrying member D-3 was prepared in the same manner as in Example 1 except that the addition amount of -1 was 300 parts by mass, and the same evaluation as in Example 1 was performed.

<Examples 4 to 7> Instead of the copolymer A-1 used in Example 1, a copolymer A was prepared in which the molecular weight of the copolymer and the molar ratio of methyl methacrylate and dimethylaminoethyl methacrylate were changed. The developer carrying members D-4 to 7 were prepared in the same manner as in Example 1 by using −2 to 5 and the same evaluation as in Example 1 was performed.

Copolymer used for developer carrier D-4 Methyl methacrylate-dimethylaminoethyl methacrylate copolymer (A-2) (solid content 40% by mass) (molar ratio 90:10, Mw = 40, 000, Mn = 19: 00
0, Mw / Mn = 2.1)

Copolymer used for developer carrier D-5 Methyl methacrylate-dimethylaminoethyl methacrylate copolymer (A-3) (solid content 40% by mass) (molar ratio 90:10, Mw = 3) 700, Mn = 2,300,
(Mw / Mn = 1.9)

Copolymer used for developer carrier D-6 Methyl methacrylate-dimethylaminoethyl methacrylate copolymer (A-4) (solid content 40% by mass) (molar ratio 70:30, Mw = 8, 500, Mn = 2,900,
(Mw / Mn = 2.9)

Copolymer used for developer carrier D-7 Methyl methacrylate-dimethylaminoethyl methacrylate copolymer (A-5) (solid content 40% by mass) (molar ratio 997: 3, Mw = 19, 000, Mn = 9,90
0, Mw / Mn = 1.9)

<Examples 8 to 10> In place of the dimethylaminoethyl methacrylate of the copolymer A-1 used in Example 1, diethylaminoethyl methacrylate, dibutylaminoethyl methacrylate and dimethylaminostyrene were used respectively, and methyl methacrylate was used. Example 1 except that copolymerized copolymers A-6 to 8 were used.
Developer carrying members D-8 to 10 were prepared in the same manner as described above and evaluated in the same manner as in Example 1.

Example 11 Instead of the dimethylaminoethyl methacrylate of the copolymer A-1 used in Example 1, the following quaternary ammonium salt group-containing vinyl monomer (5) was used and copolymerized with methyl methacrylate. Using the copolymer A-9, a developer carrying member D-11 was prepared in the same manner as in Example 1 and evaluated in the same manner as in Example 1.

<Example 12>

The above materials were dispersed in the same manner as in Example 1 to obtain a coating liquid (c (carbon) / Gf (graphite) / B (binder resin) / D (copolymer) / Z (charge control). Agent) / R (spherical particles) = 0.2 / 0.8 / 0/4/0 /
1) was obtained. Using this coating material, a developer carrying member D-12 was prepared in the same manner as in Example 1, and the same evaluation as in Example 1 was performed.

<Examples 13 to 15> Acrylic acid, methacrylic acid, and butyl maleate were used in place of the methyl methacrylate of the copolymer A-1 used in Example 12, and copolymerized with dimethylaminoethyl methacrylate. Developer carrying bodies D-13 to 15 were prepared in the same manner as in Example 1 except that the copolymers A-10 to 12 were used, and the same evaluation as in Example 1 was carried out.

<Examples 16 to 18> In place of the copolymer A-1 used in Example 1, the following copolymers A-13 to 15 which are terpolymers were used. Developer carrying members D-16 to 18 were prepared in the same manner and evaluated in the same manner as in Example 1.

Copolymer used for developer carrier 16 Methyl methacrylate-dimethylaminoethyl methacrylate-acrylic acid copolymer (A-13) (50% by mass)
MEK solution) (molar ratio 90: 5: 5, Mw = 1,50
0, Mn = 4,800, Mw / Mn = 2.4)

Copolymer used for developer carrier 17 Methyl methacrylate-dimethylaminoethyl methacrylate-methacrylic acid copolymer (A-14) (50% by mass MEK solution) (molar ratio 90: 5: 5, Mw = 12,5
00, Mn = 5,700, Mw / Mn = 2.2)

Copolymer used for developer carrier 18 Methyl methacrylate-dimethylaminoethyl methacrylate-butyl maleate copolymer (A-15) (50
Mass% MEK solution) (molar ratio 90: 5: 5, Mw = 1
1,900, Mn = 4,900, Mw / Mn = 2.4)

<Example 19>

As the nitrogen-containing heterocyclic compound, imidazole compound particles represented by the following general formula B-1 and having a number average particle diameter of 3 μm were used.

The above materials were dispersed in the same manner as in Example 1 to obtain a coating liquid (c (carbon) / Gf (graphite) / B (binder resin) / D (copolymer) / Z (charge control). Agent) / R (spherical particles) = 0.2 / 0.8 / 3/0/0.
5 / 0.6) was obtained. This coating material was used in the same manner as in Example 1 to prepare a developer carrier D-19, and the same evaluation as in Example 1 was performed.

Example 20 As the nitrogen-containing heterocyclic compound, imidazole compound particles represented by the following general formula B-2 and having a number average particle size of 5 μm were used. Nitrogen-containing heterocyclic compound B-1 used in the coating liquid of Example 19
A developer carrying member D-20 was prepared in the same manner as in Example 19 except that B-2 was added instead of, and the phenol resin was replaced with a polyester resin, and the same evaluation as in Example 1 was performed. went.

Example 21 As a nitrogen-containing heterocyclic compound, a number average particle size represented by the following general formula B-3 is 1.5 μm.
m imidazole compound particles were used. Nitrogen-containing heterocyclic compound B-1 used in the coating liquid of Example 19
A developer carrying member D-21 was prepared in the same manner as in Example 19 except that B-3 was added instead of, and the phenol resin was replaced with an acrylic-modified silicone resin. An evaluation was made.

Example 22 As a nitrogen-containing heterocyclic compound, a number average particle size represented by the following general formula B-4: 1.5 μm
m imidazole compound particles were used. Nitrogen-containing heterocyclic compound B-1 used in the coating liquid of Example 19
Example 19 except that B-4 was added instead of, and the phenol resin was replaced with a polycarbonate resin.
A developer carrying member D-22 was prepared in the same manner as in
The same evaluation as was done.

<Example 23> A developer carrying member D-23 was prepared in the same manner as in Example 1 except that the copolymer A-1 was not added, and the same evaluation as in Example 1 was carried out. I went.

<Example 24> As a spherical particle, 100 parts by mass of a spherical phenol resin particle having a number average particle diameter of 5.1 μm was used, and a Reika machine (automatic mortar, manufactured by Ishikawa Factory) was used to obtain the number average particle diameter of 1.4 μm or less. The number obtained by uniformly coating 14 parts by mass of coal-based bulk mesophase pitch powder, heat-stabilizing in air at 280 ° C., then graphitizing by firing at 2,000 ° C. in a nitrogen atmosphere, and further classifying Spherical conductive carbon particles having an average particle diameter of 3.8 μm (spherical particles C
-2) was used. Table 1 shows the physical properties of the spherical particles C-2.
The developer carrying member D- in the same manner as in Example 1 except that 120 parts by mass of the spherical particles C-2 was added instead of adding 70 parts by mass of the spherical particles C-1 used in the coating liquid of Example 1. 24
Was prepared and evaluated in the same manner as in Example 1.

Example 25 As a spherical particle, 100 parts by mass of a spherical phenol resin particle having a number average particle size of 19.5 μm was used, and a number of particles having a number average particle size of 1.4 μm or less was measured by using a Reika machine (automatic mortar, manufactured by Ishikawa Factory). Uniformly coat 14 parts by mass of coal-based bulk mesophase pitch powder in air at 280 ° C.
Spherical conductive carbon particles having a number average particle size of 19.8 μm (spherical particles C-3) obtained by graphitizing by firing at 2,000 ° C. in a nitrogen atmosphere after heat stabilization treatment with, and further classification. Using. Table 1 shows the physical properties of the spherical particles C-3. Developer carrying member D- in the same manner as in Example 1 except that 40 parts by mass of spherical particles C-3 were added instead of 70 parts by mass of spherical particles C-1 used in the coating liquid of Example 1. Two
5 was produced and evaluated in the same manner as in Example 1.

Comparative Example 1 A developer carrying member E-1 was prepared in the same manner as in Example 23 except that the phenol resin used in the coating liquid of Example 23 was replaced with a fluororesin. The same evaluation as was done.

<Comparative Example 2> A developer carrying member E-2 was prepared in the same manner as in Example 23 except that the phenol resin used in the coating liquid of Example 23 was replaced with a polyester resin. The same evaluation as was done.

<Comparative Example 3> A developer carrying member E- was prepared in the same manner as in Example 23 except that the phenol resin used in the coating liquid of Example 23 was replaced with an acrylic modified silicone resin.
3 was produced and evaluated in the same manner as in Example 1.

<Comparative Example 4> A developer carrying member E-4 was prepared in the same manner as in Example 23 except that the phenol resin used in the coating liquid of Example 23 was replaced with a polycarbonate resin. The same evaluation as was done.

[0163]

[0164] MMA: methyl methacrylate, AA: acrylic acid, M
A: Methacrylic acid, MB: Butyl maleate, DM: Dimethylaminoethyl methacrylate, DE: Diethylaminoethyl methacrylate, DB: Dibutylaminoethyl methacrylate, DS: Dimethylaminostyrene

[0165]

[0166] * 1 c: carbon black, Gf: crystalline graphite, B: binder resin, D: copolymer, Z: charge control agent,
R: Spherical particle

[0167]

[0168]

[0169]

[0170]

[0171]

As described above, according to the present invention,
The triboelectric charge of the carrier on the developer carrying member is 0.01
By providing a developer carrying member having a mC / kg or less, it is possible to form a suitable frictional charging relationship between the developer carrying member and the carrier, and between the developer carrying member and the toner. It is possible to suppress the generation of reverse toner and improve the collectability of transfer residual toner, and it is possible to provide an image forming apparatus suitable for a cleanerless system.

Further, according to the present invention, even when the spherical toner having a high transferability, which is useful for the cleanerless system, is used, the toner is not fixed on the carrier sleeve due to the charge-up, and the development is performed. It is possible to provide an image forming apparatus capable of appropriately controlling the chargeability and transportability of the agent and effectively preventing fog, blotch, image density reduction, carrier adhesion, and character scattering.

Further, according to the present invention, even when the developer carrying substrate which is excellent in workability and low in cost is used, it is excellent in abrasion resistance and is durable for a long time in any environment.
An image forming apparatus that can obtain a stable image can be provided.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of an image forming apparatus of the present invention.

FIG. 2 is a schematic diagram of a layer configuration of a photosensitive drum and a charging roller.

FIG. 3 is a schematic diagram of a triboelectric charge amount measuring device for a developer.

[Explanation of symbols]

1: Photosensitive drum (image carrier) 1a: Aluminum cylinder 1b: Undercoat layer 1c: Photoelectric charge generation layer 1d: charge transport layer 2: charging roller 2a: Core bar (support member) 2b: Lower layer of charging roller 2c: Charging roller intermediate layer 2d: Surface layer of charging roller 2e: Pressing spring 2f: Cleaning film 2g: Support member 3: Laser beam scanner 4: Developing device 4a: developing container 4b: developing sleeve 4c: Magnet roller 4d: developer coating blade 4e: Two-component developer 4f: developer stirring member 4g: Toner hopper 5: Transfer roller 6: Fixing device 7: toner charge amount control means (developer charge amount control means) 31: Suction port 32: Filter 33: Faraday gauge S1 to S4: Bias voltage application power source a: Charged part b: exposure position c: Development section d: transfer part e: Contact part L: Laser light P: Transfer material

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08F 226/06 C08K 5/34 C08K 5/34 7/16 7/16 C08L 33/12 C08L 33/12 33/14 33 / 14 33/26 33/26 39/04 39/04 101/00 101/00 G03G 9/10 G03G 9/10 21/00 9/107 15/08 507B 9/113 9/10 351 21/00 331 ( 72) Inventor Kazuki Saiki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Kenji Fujishima 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Masayoshi Shimamura 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Naoki Okamoto 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. F-term (reference) 2H005 BA03 BA06 EA01 2H077 AA37 AC01 AC16 AD02 AD06 AD13 AD17 EA01 FA13 FA25 2H134 GA01 GB02 HF13 JA05 JA11 JA14 JB01 JB07 KA15 KA20 KA24 KB12 KB14 KG01 KG03 KG07 KG08 KH01 MA02 MA11 MA14 4J002 AB011 AC033 B B001 BB023 BB113 BC013 BC021 BC023 BC042 BC092 BD121 BD123 BG001 BG012 BG042 BG043 BG052 BG053 BG062 BG072 DA03 DA030 DD008 DE096 DE126 DG028 DJ048 DK008 EU007 EU027 EU047 EU057 EU107 EU117 EU137 EU147 EU167 EU177 EU187 EU217 EU227 EU237 EV087 EV197 EV237 EV267 EV287 EV317 EV327 EV357 EW157 FA046 FA083 FA089 FB073 FB093 FB103 FB113 FB143 FB153 FB263 FD116 FD178 GF00 GH00 GQ02 GS00 4J100 AB02P AB03P AB07Q AJ02P AJ09P AL03P AL04P AL08P AL08Q AL34P AL36P AM02P AM15P AM21Q AQ06Q AQ15Q AQ19Q AQ26Q BA29Q BA30Q BA31P BA31Q BA32Q BC04P CA04 DA01 DA04 JA45

Claims (21)

[Claims] 1. An image carrier, a charging unit for charging the surface of the image carrier, an information writing unit for forming an electrostatic latent image on the charged image carrier, and a developing unit housed in a developing container. A developer carrying body carrying the developer, a developer layer thickness regulating member for regulating the layer thickness of the developer carried on the developer carrying body, and a developer carrying the developer carried on the developer carrying body A means for conveying to the developing area where the carrier and the electrostatic latent image carrier face each other, a means for developing the electrostatic latent image formed on the latent image carrier, and a visualized developer image as a transfer material. After the transfer means for transferring and the fixing means for heating and fixing the transferred image transferred onto the transfer material, and the means for developing the electrostatic latent image, after transferring the developed image to the transfer material, Image forming apparatus also serving as a cleaning unit for collecting the developer remaining on the latent image holding member In the above, the developer is a two-component developer consisting of a negatively chargeable non-magnetic toner and carrier particles having magnetism, and the carrier particles of the two-component developer have a resin component on at least the surface thereof, The agent carrier has at least a substrate and a conductive coating layer provided on the substrate, and the triboelectric charge amount of the carrier when the non-magnetic toner on the developer carrier is removed is 0.01 mC / kg.
An image forming apparatus comprising: 2. The image forming apparatus according to claim 1, wherein the carrier is a magnetic substance dispersion type carrier in which a magnetic substance is dispersed in a binder resin. 3. The conductive coating layer on the developer carrier is formed of a resin composition containing at least a binder resin and conductive fine particles dispersed in the binder resin. The image forming apparatus described. 4. The image forming according to claim 3, wherein the resin coating layer provided on the developer carrying member has a positive charging property, and the resin coating layer contains a charge-controllable nitrogen-containing compound. apparatus. 5. The resin coating layer provided on the developer carrier has a positive charging property, and the resin coating layer contains a copolymer containing a vinyl polymerizable monomer and a nitrogen-containing vinyl monomer. The image forming apparatus according to claim 3. 6. The image forming apparatus according to claim 5, wherein the vinyl polymerizable monomer contains methyl methacrylate. 7. The copolymer is 3,000 to 50,000.
7. The image forming apparatus according to claim 5, having a weight average molecular weight (Mw) of. 8. The copolymer according to claim 5, wherein the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) is 3.5 or less. The image forming apparatus according to item. 9. The nitrogen-containing vinyl monomer has at least one monomer selected from the group consisting of (meth) acrylic monomers and nitrogen-containing heterocyclic N-vinyl compounds. The image forming apparatus according to item. 10. The image forming apparatus according to claim 5, wherein the nitrogen-containing vinyl monomer is represented by the following general formula (1). Wherein, R ₁ to R ₄ denotes a saturated hydrocarbon group having a hydrogen atom or 1 to 4 carbon atoms, n is an integer of 1-4. ] 11. The nitrogen-containing vinyl monomer comprises a quaternary ammonium salt group-containing vinyl monomer.
The image forming apparatus according to any one of 0. 12. The image forming apparatus according to claim 11, wherein the quaternary ammonium salt group-containing vinyl monomer is represented by the following general formula (2). [In the formula, R ₅ represents a hydrogen atom or a methyl group, and R _5
6 represents an alkylene group having 1 to 4 carbon atoms, R _{7 to} R
₉ represents a methyl group, an ethyl group or a propyl group, and X ₁
Represents -COO- or -CONH-, and A ^- is C
Anions such as l ⁻ and (1/2) SO ₄ ²⁻ are shown. ] 13. A resin coating layer provided on a developer carrying member has a positive charging property, and the resin coating layer contains at least a nitrogen-containing heterocyclic compound dispersed in a binder resin. The image forming apparatus according to claim 3, wherein 14. The image forming apparatus according to claim 13, wherein the nitrogen-containing heterocyclic compound is an imidazole compound. 15. The imidazole compound has the following formula (3):
The image forming apparatus according to claim 14, which is a compound represented by (4). [In the formula, R ₁₀ and R ₁₁ represent a hydrogen atom, an alkyl group, an aralkyl group or an aryl group, and R ₁₀ and R ₁₁ may be the same or different. R ₁₂ and R ₁₃ represent a linear alkyl group having 3 to 30 carbon atoms, and R ₁₂ and R ₁₃ may be the same. ] [In the formula, R ₁₄ and R ₁₅ represent a hydrogen atom, an alkyl group, an aralkyl group or an aryl group, and R ₁₄ and R ₁₅ may be the same. R ₁₆ represents a linear alkyl group having 3 to 30 carbon atoms. ] 16. The image forming apparatus according to claim 3, wherein the coating layer on the developer carrying member further contains spherical particles having a number average particle diameter of 0.3 to 30 μm. 17. The image forming apparatus according to claim 16, wherein the spherical particles are spherical particles made of resin. 18. The image forming apparatus according to claim 16, wherein the spherical particles are conductive spherical particles having a true density of 3 g / cm ³ or less. 19. The image forming apparatus according to claim 3, wherein the coating layer further contains lubricating particles. 20. A developer charge amount control unit located upstream of the charging unit for charging the developer on the surface of the image carrier, upstream of the developer charge amount control unit and downstream of the transfer unit. And a means for uniformizing the residual developer image remaining on the surface of the image carrier after the developer image is transferred to the transfer material, and remains on the image carrier after the developer transfer. The residual developer image is homogenized by the residual developer image homogenizing means, and the homogenized residual developer on the image carrier is charged to a normal polarity by the developer charge amount controlling means, and by the charging means. 20. The image forming apparatus according to claim 1, wherein the surface of the image carrier is charged, and at the same time, an appropriate amount of charge is set. 21. The image forming apparatus according to claim 20, wherein the residual developer image uniformizing means is composed of an electrode portion having a potential difference with respect to the image carrier.