JP2001312097A - Toner and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner having stable chargeability without being affected by environment, free from fogging, and capable of obtaining an image high in density and excellent in reproducibility even for long-term use. SOLUTION: The toner contains toner particles containing at least a binder resin and iron oxide and has the following characteristics. (i) The ratio (B/A) of the iron element content (B) to the carbon element content (A) present on the toner surface measured by X-ray photoelectron spectroscopy is <0.01. (ii) Toner particles satisfying the relation of D/C<=0.02, wherein C is the projected area diameter of the toner and D is the minimum distance between iron oxide and the toner surface in the cross section of the toner observed by using a transmission electron microscope(TEM), are included by >=50% by number. (iii) The toner has 0.970 mean circularity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner used in a recording method utilizing an electrophotographic method, an electrostatic recording method, a magnetic recording method, a toner jet recording method, and the like, and an image forming method. More specifically, the present invention relates to a toner used in a copying machine, a printer, and a facsimile, which forms a toner image on an electrostatic latent image carrier in advance and then transfers the image on a transfer material to form an image, and an image forming method.

[0002]

2. Description of the Related Art Conventionally, many methods have been known as electrophotography. Generally, a photoconductive substance is used, and an electrostatic image carrier (hereinafter referred to as "photoconductor") is used by various means.
An electric latent image is formed thereon, and then the latent image is developed with toner to form a visible image. If necessary, the toner image is transferred to a transfer material such as paper. A copy is obtained by fixing a toner image thereon.

As a method for visualizing an electric latent image, a cascade developing method, a magnetic brush developing method, a pressure developing method and the like are known.

US Pat. No. 3,909,258 proposes a method of developing using a magnetic toner having electrical conductivity. This supports the conductive magnetic toner on a cylindrical conductive sleeve with magnetism inside,
This is brought into contact with the electrostatic image and developed. At this time, in the developing unit, a conductive path is formed by the toner particles between the surface of the recording medium and the surface of the sleeve, and electric charges are guided to the toner particles from the sleeve via the conductive path. The toner particles adhere to the image area by the Coulomb force and are developed. The developing method using the conductive magnetic toner is an excellent method that avoids the problems associated with the conventional two-component developing method, but because the toner is conductive,
There is a problem that it is difficult to electrostatically transfer the developed image from the recording medium to a final supporting member such as plain paper.

As a developing method using a high-resistance magnetic toner capable of electrostatic transfer, there is a developing method utilizing dielectric polarization of toner particles. However, such a method has a problem that the developing speed is essentially low and the density of a developed image is not sufficiently obtained, and is practically difficult.

As another developing method using a high-resistance insulating magnetic toner, toner particles are frictionally charged by friction between the toner particles, friction between the toner particles and a sleeve, and the like, and this is charged to an electrostatic image holding member. A method of developing by contact is known. However, in this method, the number of times of contact between the toner particles and the friction member is small, and the magnetic toner used has a large amount of magnetic material exposed on the surface of the toner particles. There was such a problem.

For example, in JP-A-54-43027 and JP-A-55-18656, a thin layer of a magnetic developer is applied on a developer carrier, and this is triboelectrically charged. A method of developing an image by bringing it in close proximity to an electrostatic latent image under the action of, and making contact with, without contact, a so-called jumping development method is disclosed. According to this method, it is possible to sufficiently frictionally charge the developer by applying the magnetic developer thinly on the developer carrier,
In addition, since development is performed without contacting the electrostatic latent image while supporting the developer by magnetic force, transfer of the developer to a non-image portion, that is, fogging is suppressed, and a high-definition image can be obtained. .

[0008] Such a one-component developing system does not require carrier particles such as glass beads and iron powder as in the two-component developing system, and thus the developing apparatus itself can be reduced in size and weight. Moreover,
In the two-component developing method, since it is necessary to keep the toner concentration in the developer constant, a device for detecting the toner concentration and supplying a necessary amount of toner is required. Therefore, the developing device also becomes large and heavy here. In the one-component developing system, such an apparatus is not required, so that it is preferable because it can be made small and light.

However, the developing method using the insulating magnetic toner has an unstable factor relating to the insulating magnetic toner to be used. The reason for this is that a considerable amount of fine powdered magnetic material is mixed and dispersed in the insulating magnetic toner, and a part of the magnetic material is exposed on the surface of the toner particles. The characteristics of the magnetic toner are changed, and as a result, various characteristics required for the magnetic toner, such as development characteristics and durability of the magnetic toner, are changed or deteriorated.

When the conventional magnetic toner containing a magnetic material is used, the above-mentioned problem is considered to be largely caused by the magnetic material being exposed on the surface of the magnetic toner. That is, by exposing the magnetic fine particles having relatively lower resistance than the resin constituting the toner on the surface of the magnetic toner, the toner charging performance is reduced, the toner fluidity is reduced, and further, the In use, the deterioration of the developer such as a decrease in image density due to the peeling of the magnetic material due to the rubbing between the toner or the regulating member and the occurrence of uneven density called a sleeve ghost are caused.

Conventionally, proposals have been made regarding magnetic iron oxide contained in magnetic toners, but they still have points to be improved.

For example, JP-A-62-279352 proposes a magnetic toner containing a magnetic iron oxide containing a silicon element. Such magnetic iron oxide is
Although silicon element is intentionally present inside the magnetic iron oxide, there is still a point to be improved in the fluidity of the magnetic toner containing the magnetic iron oxide.

Further, Japanese Patent Publication No. 3-9045 proposes that the shape of magnetic iron oxide is controlled to be spherical by adding a silicate. In the magnetic iron oxide obtained by this method, a large amount of silicon element is distributed inside the magnetic iron oxide because silicate is used for controlling the particle shape, and the amount of the silicon element on the surface of the magnetic iron oxide is small, The fluidity of the magnetic toner is improved to some extent due to the high smoothness of the magnetic iron oxide, but the adhesion between the binder resin and the magnetic iron oxide constituting the magnetic toner is insufficient.

JP-A-61-34070 proposes a method for producing ferric oxide by adding a hydrosilosilicate solution during the oxidation reaction to ferric oxide. Although triiron tetroxide according to this method has a Si element near the surface, the Si element exists in a layer near the surface of the triiron tetroxide, and the surface is vulnerable to mechanical shock such as friction. Have a point.

On the other hand, the toner is prepared by melting and mixing a binder resin, a colorant, and the like, uniformly dispersing the mixture, pulverizing the mixture with a fine pulverizer, and classifying with a classifier to obtain a toner having a desired particle size. Pulverization method), but there is a limit to the selection range of materials for reducing the toner particle size. For example, the resin colorant dispersion must be sufficiently brittle and capable of being pulverized with economically available manufacturing equipment. From this request,
In order to make the resin colorant dispersion brittle, when the resin colorant dispersion is actually finely pulverized at a high speed, particles having a wide particle size range are easily formed. Particles) are included in this. Further, such a highly brittle material often undergoes further pulverization or pulverization when used as a developing toner in a copying machine or the like.

In the pulverization method, it is difficult to completely and uniformly disperse solid fine particles such as a magnetic powder or a colorant in a resin, and depending on the degree of dispersion, fog increases and image density decreases. Cause. In addition, the grinding method
In essence, the magnetic iron oxide particles are exposed on the surface of the toner, so that there remains a problem in the fluidity of the toner and the charging stability in a severe environment.

That is, in the pulverization method, there is a limit to the fineness of the toner required for high definition and high image quality, and the powder characteristics, particularly, the uniform charging property and fluidity of the toner are significantly attenuated.

In order to overcome the problems of the toner by the pulverization method as described above and to satisfy the above-mentioned requirements, a method of producing a toner by a suspension polymerization method has been proposed.

The toner obtained by suspension polymerization (hereinafter referred to as “polymerized toner”) can be easily made into fine particles. Further, since the obtained toner has a spherical shape, it has excellent fluidity and high image quality. It is advantageous for conversion.

However, when a magnetic material is contained in the polymerized toner, its fluidity and charging characteristics are significantly reduced. This is because the magnetic particles are generally hydrophilic and thus easily exist on the toner surface. To solve this problem, it is important to modify the surface characteristics of the magnetic material.

Many proposals have been made regarding surface modification for improving the dispersibility of a magnetic substance in a polymerized toner. For example, JP-A-59-200254 and JP-A-59-20025
JP-A Nos. 0002526, 59-200257 and 59-224102 propose various techniques for treating a magnetic substance with a silane coupling agent. A technique for treating element-containing magnetic particles with a silane coupling agent is disclosed, and Japanese Patent Application Laid-Open No. 7-72654 discloses a technique for treating magnetic iron oxide with an alkyl trialkoxysilane.

However, although the dispersibility in the toner is improved to some extent by these treatments, there is a problem that it is difficult to uniformly render the surface of the magnetic material hydrophobic.
Therefore, it is impossible to avoid coalescence of the magnetic substances and generation of magnetic particles that are not hydrophobized, which is insufficient to improve the dispersibility in the toner to a satisfactory level.

Japanese Patent Application Laid-Open No. 7-209904 has already disclosed a special toner in which magnetic particles are contained only in a specific portion inside the particles.

However, Japanese Patent Application Laid-Open No. 7-209904 does not mention the circularity of the disclosed toner.

Further, the toner constitution disclosed in JP-A-7-209904 can be summarized as follows. From the structure in which a resin layer having no magnetic particles near the surface of the toner particles is formed with a certain thickness or more. Consisting of
This means that the toner surface layer portion where no magnetic particles exist is present in a considerable proportion. However, in other words, if the average particle diameter of such a developer is as small as 10 μm, for example, the volume in which the magnetic particles can exist is small, and thus it is difficult to include a sufficient amount of the magnetic particles. Moreover, with such a developer,
In the particle size distribution of the developer, the ratio of the surface resin layer where no magnetic particles are present differs between the developer particles having a large particle size and the developer particles having a small particle size. In contrast, the developability and transferability also differ depending on the particle size of the developer, that is, the selective developability depending on the particle size is easily observed. Therefore, when printing is performed for a long time using a magnetic developer having a non-uniform particle size, particles containing a large amount of magnetic material and difficult to develop, that is, developer particles having a large particle size are likely to remain, and the image density and image quality are reduced, and the fixing property is further reduced. Also leads to worsening.

As for printer devices, LED and LBP printers have become the mainstream in the recent market, and the direction of technology has been changed to higher resolution, that is, from 240,300 dpi to 400,600,800 dpi. ing. Accordingly, the development system is required to have higher definition. In addition, the functions of the copying machine have been advanced, and the digital copying machine is moving toward digitalization. In this direction, since the method of forming an electrostatic latent image with a laser is mainly used, the direction is also moving toward a high resolution direction.
Here, as in the case of a printer, a high-resolution and high-definition developing method is required. For this reason, the particle size of toner has been reduced, and Japanese Patent Application Laid-Open Nos.
JP-A-191156, JP-A-2-214156,
JP-A-2-284158, JP-A-3-18195
No. 2, Japanese Patent Application Laid-Open No. 4-162048 and the like propose a toner having a specific particle size distribution and a small particle size.

In recent years, from the viewpoint of environmental protection, the primary charging and transfer process using a photoreceptor contact member has been becoming the mainstream from the primary charging and transfer process using corona discharge.

In the primary charging and transfer process using corona discharge, a large amount of ozone is generated when corona discharge, particularly negative corona, is generated. Therefore, it is necessary to provide an electrophotographic apparatus with a filter for capturing ozone. There are problems such as an increase in the size of the device or an increase in running cost. Further, image problems caused by such a corona charging method include, for example, a so-called image flow caused by a decrease in the surface resistance of the photoreceptor due to the attachment of nitrogen oxide or the like, or a problem that the electrophotographic apparatus is stopped. A memory phenomenon of the photoreceptor caused by ions remaining in the charger is exemplified.

As a technique for solving such a problem, a charging member such as a roller or a blade or a transfer member is brought into contact with the surface of a photoreceptor to form a narrow space in the vicinity of the contact portion, so-called Paschen's law. A contact charging method or a contact transfer method in which the generation of ozone is suppressed as much as possible by forming a discharge which can be interpreted as described in, for example, JP-A-57-178257 and JP-A-56-1043.
No. 51, Japanese Patent Application Laid-Open No. 58-40566, and Japanese Patent Application Laid-Open
This technique is known in Japanese Patent Application Laid-Open Nos. 8-139156 and 58-150975. Among these, in particular, JP-A-63-149669 and JP-A-2-12338.
The charging method and the transfer method using a conductive elastic roller as described in Japanese Patent Publication No. 5 are preferably used from the viewpoint of stability.

However, it has been found that when the contact charging method or the contact transfer method is used, there is a problem to be concerned, unlike the case where corona discharge is used.

More specifically, in the case of the contact transfer method, the transfer member is brought into contact with the photosensitive member via the transfer member at the time of transfer, so that the toner image formed on the photosensitive member is transferred to the transfer material. Is pressed against the toner image, causing a problem of a partial transfer failure called a so-called "missing transfer". Furthermore, in recent years, there has been a demand for a higher resolution and higher definition developing method as a direction of the technology, and in order to meet such a demand, the particle diameter of the toner has been reduced. As described above, as the toner particle size becomes smaller, the adhesion force (mirror image force, van der Waals force, etc.) of the toner particles to the photoconductor becomes larger than the Coulomb force applied to the toner particles in the transfer process,
As a result, the transfer residual toner increases, and the transfer failure tends to worsen.

On the other hand, in the contact charging method, the charging member is pressed against the surface of the photosensitive member with a pressing pressure. Therefore, when the untransferred residual toner, that is, the transfer residual toner, is pressed against the surface of the photoreceptor, toner abrasion due to abrasion of the surface of the photoreceptor or toner fusing, which is a nucleus generated by the abrasion, easily occurs. It becomes more noticeable as the amount of residual toner increases.

Such scraping of the photoreceptor and fusion of the toner cause a serious defect in the formation of an electrostatic latent image on the electrostatic image carrier. Specifically, since the primary charge cannot be performed when the photosensitive member is scraped, the scraped portion appears black on the halftone image. Further, since toner fusion makes it impossible to form a latent image by exposure, a fused portion appears white on a halftone image. Further, the transferability of the toner is also deteriorated. Therefore, in combination with the above-described transfer failure, a remarkable image defect appears, and in some cases, the image quality deteriorates synergistically.

Such a problem of abrasion of the photoreceptor and poor transfer is likely to occur when a developer composed of irregular toner particles is used. This is presumably because, in addition to the low transferability of the irregular toner, the edge portion of the toner particles easily scratches the surface of the photoreceptor. Furthermore, the problem of shaving becomes particularly remarkable when a magnetic developer having a magnetic material exposed on the surface of toner particles is used. This is easily understood considering that the exposed magnetic body is directly pressed against the photoconductor.

Further, when the amount of the transfer residual toner increases, it becomes difficult to maintain a sufficient contact between the contact charging member and the photosensitive member, and the chargeability is deteriorated. That is, fogging is likely to occur. This phenomenon is often seen under low humidity where the resistance of the member tends to increase.

As described above, in an image forming method using a contact charging method and a contact transfer method, which are very preferable in consideration of the environment, a magnetic developer which has high transferability and hardly causes abrasion of a photoreceptor and toner fusing. The development of is desired.

On the other hand, when a toner image formed on the photoconductor in the developing process is transferred to a transfer material in the transfer process, if the transfer residual toner remains on the photoconductor as described above, it is cleaned in the cleaning process. Need to be stored in a waste toner container. For this cleaning step, conventionally, blade cleaning, fur brush cleaning, roller cleaning and the like have been used. In either method, the toner remaining after transfer is mechanically scraped off or dammed and collected in a waste toner container. However, pressing such a member against the surface of the photoconductor wears the photoconductor, which causes a problem of shortening the life. Further, from the viewpoint of the apparatus, the provision of such a cleaning apparatus inevitably increases the size of the apparatus, which has been a bottleneck when aiming for a more compact apparatus. Furthermore, from an ecological point of view,
A system that does not generate waste toner in the sense of effective use of toner is desired.

Here, Japanese Patent Application Laid-Open Nos. Sho 59-133573, Sho 62-203182, and Sho 63-1 disclose cleaner related technologies.
No. 33179, JP-A-64-20587, JP-A-2-302772, JP-A-5-2289, JP-A-5-53482, JP-A-5-6138
There is a publication No. 3 which does not mention a desirable toner configuration.

Further, Japanese Patent Application Laid-Open No. 61-279864 proposes a toner in which the shape factors SF-1 and SF-2 are specified. However, this publication has no description about transfer, and as a result of additional testing of the examples, the transfer efficiency is low, and further improvement is required.

Furthermore, Japanese Patent Application Laid-Open No. 63-235953 proposes a spherical magnetic toner by a mechanical impact force. However, the transfer efficiency is still inadequate and further improvements are needed.

In the developing / cleaning configuration essentially having no cleaning device, the surface of the photoreceptor is rubbed with toner and a toner carrier, the toner in the non-image area is collected by the toner carrier, and the image area is In such a case, it is necessary to provide a configuration for developing. At the time of this rubbing, if the oppositely charged toner such as the transfer residual toner or the fogging toner can be easily inverted to the positively charged state, the potential recovery becomes easy.

Conventionally, when a toner containing a magnetic material is used in a developing and cleaning configuration, since the magnetic material is exposed on the toner surface, a gap between the photoreceptor and the toner carrying member via the toner is required during development. Partial conduction occurs, and the electrostatic charge image on the photoreceptor is disturbed, making it difficult to obtain a high-definition image. Further, in the case of a magnetic toner in which a magnetic material is exposed on the surface of the toner, the transfer residual toner is insufficiently charged, which hinders smooth recovery of the toner on the photoconductor in the developing process. Further, when the photoconductor is rubbed between the toner and the toner carrier, the magnetic body exposed on the toner surface wears the photoconductor intensely, thereby shortening the life of the photoconductor. As a result, a print image that is originally an image-free area stained with a toner in an image form, that is, a so-called ghost image is obtained.

As described above, it is desired that the magnetic material-containing toner used in the developing / cleaning structure has no magnetic material exposed on the toner surface.

When the pressing force of the cleaning member is weakened to extend the life of the photosensitive member, the amount of transfer residual toner that passes through the cleaning member increases accordingly. It can be said that this is very important in the recovery system in the above.

When the conventional magnetic toner containing a magnetic material is used, the above-described problem occurs because the conventional magnetic toner has a problem that the magnetic material is exposed on the toner surface. It is a big cause. In the case of a magnetic toner in which a magnetic material is exposed on the surface of the toner, the resistance of the magnetic material is lower than the resistance of the resin of the toner, so that the charging characteristics under high humidity tend to be poor, fog suppression is deteriorated, and transfer is performed. This leads to undesirable effects such as ghosting due to a reduction in transferability, a reduction in recoverability of transfer residual toner, and a deterioration in photoreceptor performance due to friction with the photoreceptor.

That is, a magnetic toner having good initial characteristics and stability in the developing and cleaning configuration has not been found so far.

[0047]

SUMMARY OF THE INVENTION An object of the present invention is to provide a toner and an image forming method which solve the above-mentioned problems of the prior art.

The object of the present invention is to be less affected by the environment,
An object of the present invention is to provide a toner which has stable charging performance, has a high image density even when used for a long time, suppresses fogging, and has excellent image reproducibility.

An object of the present invention is to solve the above-mentioned various problems in a contact developing type image forming process which can also cope with a cleaner-less configuration, without being affected by the environment.
The occurrence of fog and ghost is suppressed, and the resolution,
An object of the present invention is to provide an image forming method having excellent transferability and durability.

An object of the present invention is to provide an image forming method which combines a contact charging step with less ozone generation and a non-contact developing step with less fogging using a one-component developer because it has high transferability. It is an object of the present invention to provide an image forming method in which an image defect is less likely to occur even when used for a long period of time by using a magnetic developer which has a small amount of residual toner such as omission during transfer and hardly scrapes the surface of a photoreceptor.

An object of the present invention is to provide an image forming method capable of stably forming an electrostatic latent image even in a low-humidity environment and having few image defects such as fog due to a decrease in charging property during durability. It is in.

[0052]

According to the present invention, there is provided toner particles containing at least a binder resin and iron oxide, and i) carbon present on the toner surface as measured by X-ray photoelectron spectroscopy. The ratio (B / A) of the iron element content (B) to the element content (A) is less than 0.001,
ii) When the projected area equivalent diameter of the toner is C, and the minimum value of the distance between the iron oxide and the toner surface in cross-sectional observation of the toner using a transmission electron microscope (TEM) is D / C,
50% by number or more of toner satisfying the relationship of ≦ 0.02, and iii) the toner has an average circularity of 0.970 or more.

Further, the present invention provides a charging step of charging an electrostatic image carrier by a charging member to which an external voltage is applied; an exposure step of forming an electrostatic latent image on the electrostatic image carrier by exposure; A developing step of developing the electrostatic latent image with toner carried on a toner carrier to form a toner image;
And a transfer step of transferring a toner image to a transfer material, wherein the toner has toner particles containing at least a binder resin and iron oxide,
i) the ratio (B / A) of the content (B) of the iron element to the content (A) of the carbon element present on the toner surface measured by X-ray photoelectron spectroscopy is less than 0.001, and ii)
When the projected area equivalent diameter of the toner is C and the minimum value of the distance between the iron oxide and the toner surface in cross-sectional observation of the toner using a transmission electron microscope (TEM) is D, D / C ≦
The present invention relates to an image forming method, wherein 50% by number of toners satisfy the relationship of 0.02 and iii) the average circularity of the toner is 0.970 or more.

[0054]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have conducted intensive studies on the uniformity and stabilization of the charging of a magnetic toner so far, and as a result, the carbon element existing on the surface of the magnetic toner as measured by X-ray photoelectron spectroscopy analysis. Ratio (B / A) of the iron element content (B) to the iron content (A) is less than 0.001, and the following formula

[0055]

[Outside 1] (Where L ₀ represents the circumference of a circle having the same projected area as the particle image, and L represents the circumference of the projection image of the particle.) The average of the toner calculated from the circularity obtained by The inventors have found that setting the circularity to 0.970 or more is extremely effective in making the chargeability of the toner uniform and stabilizing, and have reached the present invention.

Also, by using the toner as described above, an image forming method combining a cleaner-less structure and contact charging in which a ghost image is likely to be generated due to poor toner collection, a contact charging step and a one-component non-contact developing step Also, in the image forming method including the contact transfer step, the shaving of the photoreceptor, charging failure and transfer failure are remarkably suppressed, and a high-definition image free of fog and other image defects can be stably obtained over a long period of use. The present invention has been found, and the present invention has been achieved.

This has been difficult to achieve with a magnetic toner using magnetic iron oxide which has been generally used conventionally.

The reason is that the magnetic iron oxide to be used was not sufficiently and uniformly hydrophobicized.

When a magnetic toner is produced, the dispersibility of the magnetic iron oxide particles in the toner binder resin can be improved by using magnetic iron oxide whose surface has been hydrophobized. Even when a large amount of magnetic iron oxide is exposed on the surface, if the surface of the magnetic iron oxide is uniformly subjected to the hydrophobic treatment, it becomes difficult to impair the charging performance of the toner under any environment.

Therefore, various methods have been proposed for hydrophobizing the surface of magnetic iron oxide particles. However, it has been difficult for conventional methods to obtain magnetic iron oxide that has been sufficiently and uniformly hydrophobized. In addition, when using a large amount of a processing agent or the like, or using a highly viscous processing agent or the like,
Although the degree of hydrophobicity is certainly increased, coalescence of particles occurs, and both hydrophobicity and dispersibility have not always been achieved.

In general, the surface of an untreated iron oxide has a hydrophilic property. Therefore, in order to obtain a hydrophobic iron oxide, it is necessary to hydrophilize the hydrophilic iron oxide. According to the method, the uniformity of hydrophobization is insufficient, and the conventional toner using such iron oxide varies in chargeability depending on humidity and the like, and lacks stability.

On the other hand, iron oxide used as a magnetic material in the toner of the present invention has a very high level of uniformity of hydrophobicity. Iron oxide obtained by performing a surface treatment while hydrolyzing a coupling agent while dispersing iron oxide in a medium to have a primary particle size. In the hydrophobic treatment method in an aqueous medium, the coalescence of iron oxide particles is less likely to occur than in a gas phase treatment, and the charge repulsion between the iron oxide particles due to the hydrophobic treatment acts. Since the surface treatment is performed in a substantially primary particle state, high uniformity of hydrophobicity is achieved.

The method of treating the iron oxide surface while hydrolyzing the coupling agent in an aqueous medium does not require the use of a coupling agent that generates a gas such as chlorosilanes or silazanes, and furthermore, In the gas phase, iron oxide particles are easily united with each other, and a high-viscosity coupling agent, which has been difficult to treat well, can be used, and the effect of hydrophobization is enormous.

Examples of the coupling agent that can be used in the present invention include a silane coupling agent and a titanium coupling agent. More preferably used are silane coupling agents of the general formula R _m SiY _n [wherein, R represents an alkoxy group, m represents an integer of 1 to 3, Y is an alkyl group, vinyl group, glycidoxy group And a hydrocarbon group such as a methacryl group, and n represents an integer of 1 to 3. ]. For example, vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, methyltrimethoxysilane, methyltriethoxysilane, isobutyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, trimethyl Examples include methoxysilane, hydroxypropyltrimethoxysilane, phenyltrimethoxysilane, n-hexadecyltrimethoxysilane, and n-octadecyltrimethoxysilane.

[0065] In particular, the formula _{C p H 2p + 1 -Si- (} OC q H 2q + 1) 3 [ wherein, p represents an integer of 2 to 20, q is an integer of 1 to 3 represented by The iron oxide is preferably subjected to a hydrophobic treatment in an aqueous medium by using an alkyltrialkoxysilane coupling agent.

When p in the above formula is smaller than 2, the hydrophobic treatment becomes easy, but it is difficult to impart sufficient hydrophobicity. When p is larger than 20, the hydrophobicity is sufficient. In addition, coalescence between the iron oxide particles increases, and it becomes difficult to sufficiently disperse the iron oxide particles in the toner.

When q is larger than 3, the reactivity of the silane coupling agent is reduced, and it is difficult to make the silane coupling agent sufficiently hydrophobic.

In particular, alkyl in which p represents an integer of 2 to 20 (more preferably an integer of 3 to 15) and q represents an integer of 1 to 3 (more preferably an integer of 1 or 2). It is preferable to use a trialkoxysilane coupling agent.

The amount of treatment is preferably 0.05 to 20 parts by mass, and more preferably 0.1 to 10 parts by mass, per 100 parts by mass of iron oxide.

In the present invention, the aqueous medium is a medium containing water as a main component. Specifically, water itself as an aqueous medium, one obtained by adding a small amount of a surfactant to water,
Examples thereof include those obtained by adding a pH adjuster to water and those obtained by adding an organic solvent to water. As the surfactant, a nonionic surfactant such as polyvinyl alcohol is preferable.
The surfactant is preferably added in an amount of 0.1 to 5% by mass relative to water. Examples of the pH adjuster include an inorganic acid such as hydrochloric acid.

The stirring is performed by, for example, a mixer having a stirring blade (specifically, a high shear mixing device such as an attritor or a TK homomixer).
It is better to carry out sufficiently so as to become primary particles.

Since the surface of the iron oxide particles thus obtained is uniformly subjected to hydrophobic treatment, when used as a toner material, the dispersibility in the toner is very good, and there is no exposure from the toner surface. . Therefore, by using such iron oxide, the content (A) of the carbon element present on the surface of the toner measured by X-ray photoelectron spectroscopy
Ratio (B / A) of the iron element content (B) to
It is possible to obtain the toner of the present invention of less than 01, uniformity and stabilization of charge of the toner can be achieved, and by using this toner, high image quality and high durability stability can be achieved. Further, when (B / A) is less than 0.0005, the chargeability and the stability are further improved.

The iron oxide used in the toner of the present invention is produced, for example, by the following method.

An aqueous solution containing ferrous hydroxide is prepared by adding an equivalent such as sodium hydroxide to the aqueous solution of ferrous sulfate in an amount equivalent to or more than the equivalent of the iron component. Air is blown in while maintaining the pH of the prepared aqueous solution at pH 7 or more (preferably pH 8 to 10), and while the aqueous solution is heated to 70 ° C. or more, the oxidation reaction of ferrous hydroxide is carried out. First, a seed crystal is produced.

Next, an aqueous solution containing about 1 equivalent of ferrous sulfate based on the amount of the alkali added previously is added to the slurry-like liquid containing the seed crystals. The reaction of ferrous hydroxide is promoted while blowing air while maintaining the pH of the solution at 6 to 10 to grow magnetic iron oxide particles with the seed crystal as a core. The pH of the solution shifts to the acidic side as the oxidation reaction proceeds, but it is preferable that the pH of the solution is not less than 6. At the end of the oxidation reaction, adjust the pH of the solution, stir well so that the magnetic iron oxide becomes primary particles, add the coupling agent, mix and stir well, filter, dry, and lightly disintegrate after stirring. By doing so, hydrophobically treated magnetic iron oxide particles are obtained. Or,
After completion of the oxidation reaction, the iron oxide particles obtained by washing and filtration are redispersed in another aqueous medium without drying, and the pH of the redispersed liquid is adjusted. A coupling treatment may be performed by adding a ring agent.

In any case, it is important to hydrophobize the untreated iron oxide particles formed in the aqueous solution in a state of a water-containing slurry before passing through a drying step. This is because if untreated iron oxide particles are dried as they are, coalescence due to agglomeration of the particles is inevitable. Even if wet agglomerated treatment is applied to such agglomerated powder, a uniform hydrophobizing treatment is performed. In the toner using such a surface-treated iron oxide, B / A <0.0 as in the toner according to the present invention.
It is difficult to achieve 01.

As the ferrous salt, generally, iron sulfate produced as a by-product in the production of titanium sulfate and iron sulfate produced as a by-product of cleaning the surface of a steel sheet can be used. Further, iron chloride and the like can be used. is there.

The method for producing magnetic iron oxide by the aqueous solution method generally uses an iron concentration of 0.5 to 2 mol / liter from the viewpoint of preventing the viscosity from increasing during the reaction and the solubility of iron sulfate. Generally, the lower the concentration of iron sulfate, the smaller the particle size of the product tends to be. In addition, in the reaction, as the amount of air is larger and the reaction temperature is lower, the particles are easily atomized.

By using the thus-prepared hydrophobic iron oxide particles for a toner, a toner of the present invention having excellent image characteristics and stability can be obtained.

JP-B-60-3181 also discloses a method for producing a magnetic polymerized toner containing magnetic fine particles whose surface is wet-treated with a silane coupling agent.

However, Japanese Patent Publication No. Sho 60-3181 describes a wet surface treatment of an untreated magnetic material in the form of a dry powder with a silane coupling agent.

In such an untreated dry magnetic powder, coalescence of particles due to primary agglomeration during drying is inevitable. Therefore, even if a wet surface treatment is performed, uniform hydrophobicization of individual magnetic particles is not achieved. Have difficulty. Therefore, even if a polymerized toner is manufactured using such a surface-treated magnetic material, it is difficult to achieve B / A <0.001, which is a feature of the toner according to the present invention.

When the projected area equivalent diameter of the toner is C and the minimum value of the distance between the iron oxide and the toner surface in cross-sectional observation of the toner using a transmission electron microscope (TEM) is D, D / C ≦ 0 .02 is 5
0% or more is also one of the embodiments required for the toner of the present invention.

In the present invention, the number of toners satisfying the relationship of D / C ≦ 0.02 needs to be 50% or more, preferably 65% or more, and more preferably 75% or more.

When the number of toners that satisfies the relationship of D / C ≦ 0.02 is less than 50%, no magnetic particles exist at least outside the boundary of D / C = 0.02 in the majority of toners. Will be. Assuming that such particles are spherical, at least 11.5% of the space where iron oxide does not exist on the surface of the toner when one toner is used as the whole space. In fact, it is clear that the iron oxide is 12% or more because the iron oxide is not uniformly arranged at the closest position so as to form an inner wall inside the toner. In the toner composed of such particles, various adverse effects are likely to occur as described above.

In the present invention, specific D by TEM
As a method of measuring / C, a cured product obtained by sufficiently dispersing particles to be observed in a room temperature curable epoxy resin and then curing the same in an atmosphere at a temperature of 40 ° C. for 2 days is used as it is or frozen. A method of observing a flaky sample with a microtome provided with diamond teeth is preferred.

The specific method of determining the ratio of the number of particles is as follows. For the particles for determining D / C by TEM, the equivalent circle diameter was determined from the cross-sectional area in a micrograph, and the value was ± 10% of the number average particle diameter determined by the method described below using a Coulter counter. And the minimum value (D) of the distance from the magnetic particle surface to 100 corresponding particles is measured.
/ C is calculated, and the ratio of particles having a D / C value of 0.02 or less is calculated. The micrograph at this time is preferably at a magnification of 10,000 to 20,000 times in order to perform highly accurate measurement. In the present invention, a transmission electron microscope (H-600 manufactured by Hitachi) is used as an apparatus, and observation is performed at an acceleration voltage of 100 kV.
Observation and measurement were performed using a microphotograph at a magnification of 10,000.

B / A <0.001 is satisfied, and D / C ≦
A toner in which the number of toners satisfying the relationship of 0.02 is 50% or more means that the magnetic material is localized on the toner surface, or conversely, is extremely encapsulated and unevenly distributed in the toner. The toner is not a toner like the one described above, but the magnetic substance is substantially uniformly dispersed in the toner and the exposure of the magnetic substance to the toner surface is suppressed. If the dispersion state of the magnetic material is not uniform, it is difficult to satisfy the requirements of the present invention.

When a magnetic developer in which iron oxide is hardly exposed on the surface of the toner particles is used, an image forming method in which the toner is pressed against the surface of the electrostatic image carrier by a charging member, a transfer member or the like is also used. In addition, the surface of the electrostatic image carrier is hardly shaved, and the shaving of the electrostatic image carrier and the fusion of the toner can be significantly reduced over a long period of time.

The iron oxide used in the toner of the present invention is preferably used in an amount of 10 to 200 parts by mass, more preferably 20 to 180 parts by mass, based on 100 parts by mass of the binder resin. When the amount of iron oxide is less than 10 parts by mass, the coloring power of the developer is poor, and it is difficult to suppress fog.
If the amount exceeds 200 parts by mass, the coercive force due to the magnetic force applied to the developer carrier is increased and the developability is reduced, and not only is it difficult to uniformly disperse the iron oxide in the individual toner particles, but also the fixability is reduced. Would.

Next, the circularity of the toner, which is another feature of the present invention, will be described. In order to reduce the amount of toner attached to the non-image portion on the electrostatic image carrier and the amount of toner remaining after transfer, it is necessary that the chargeability of the toner particles is sufficient and uniform. Further, when a toner having a small particle diameter is used from the viewpoint of improving image quality, the adhesive force of the toner particles increases, so that the shape of the toner particles has a great effect on the toner adhesion to the non-image portion on the electrostatic image carrier. Effect. In other words, the closer the toner particles are spherical and the shape is uniform, the smaller the adhesion area of the particles, the smaller the amount of toner attached to the non-image area on the electrostatic image carrier and the amount of residual toner on the transfer, and high image quality and durability Stability is achieved.

In addition, the toner particles according to the present invention have sufficient chargeability and, as described above, the adhesion of the toner particles is reduced, so that the toner particles can be transferred from the electrostatic image bearing member to a transfer material such as paper. Is also greatly improved. This can be said to be an important toner performance for achieving high resolution as well as reproducibility of a minute dot image.

Therefore, in the toner of the present invention, the average circularity of the toner needs to be 0.970 or more, thereby achieving high image quality and high stability.

Therefore, if such a developer is used, the amount of toner remaining after transfer is greatly reduced, so that the amount of toner present in the pressure contact portion between the charging member and the photosensitive member is very small, and the image forming process having the contact charging step is performed. Also in the method, it is considered that abrasion of the photoreceptor and fusion of the toner are prevented, and image defects are remarkably suppressed. Furthermore, the average circularity is 0.97
Since the toner of 0 or more has almost no edge on the surface,
Since the surface of the photoconductor is not scratched at the pressure contact portion between the charging member and the photoconductor, it is also possible to prevent the surface of the photoconductor from being scraped.

These effects are remarkable also in an image forming method including a contact transfer step in which omission is likely to occur during transfer.

The toner of the present invention preferably has a weight average particle size of 2 to 10 μm.

When the weight average particle diameter of the toner exceeds 10 μm, the reproducibility of a minute dot image is reduced.
The charging stability of the toner under the severe environment obtained by the present invention cannot be sufficiently exhibited. On the other hand, when the weight average particle diameter of the toner is smaller than 2 μm, even if the special iron oxide of the present invention is used, the fluidity of the toner is remarkably lowered, and problems such as fogging and light density due to poor charging are likely to occur. Become.

That is, in the toner of the present invention, remarkable effects such as improvement of charging stability and fluidity appear on an image as compared with the conventional example because the weight average particle diameter is 2 to 10 μm (more preferably, 3 to 10 μm), and further preferably 3.5 to 8.0 μm from the viewpoint of further improving the image quality.

Next, a method for producing a toner according to the present invention will be described.

The toner of the present invention can be produced by a pulverization method. In the pulverization method, mechanical, thermal or some special treatment is carried out in order to make the average circularity of the toner 0.970 or more. Therefore, it is preferable to produce by a suspension polymerization method. Even when a toner is manufactured by suspension polymerization using a normal magnetic material, the magnetic material is unevenly distributed on the toner surface due to poor dispersibility, or the magnetic material is disordered during granulation in an aqueous medium. And the particle shape is distorted by being dragged by it, it has been difficult to obtain a toner having an average circularity of 0.970 or more, but the iron oxide used in the present invention has a high level. Due to the uniform hydrophobicity, a toner having an average circularity of 0.970 or more can be easily obtained.

The polymerizable monomers constituting the polymerizable monomer system used in the present invention include the following.

Examples of the polymerizable monomer include styrene-based monomers such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, and p-ethylstyrene; methyl acrylate, acrylic Such as ethyl acrylate, n-butyl acrylate, isobutyl acrylate, n-propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, and phenyl acrylate Acrylic esters: methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, methacrylic acid Le acid phenyl, dimethylaminoethyl methacrylate, such as methacrylic acid esters of diethylaminoethyl methacrylate; acrylonitrile, methacrylonitrile, acrylamide.

These monomers can be used alone or as a mixture. Among the above-mentioned monomers, it is preferable to use styrene or a styrene derivative alone or in combination with another monomer from the viewpoint of the developing characteristics and durability of the toner.

It is also one of the preferable usage forms that the toner of the present invention contains a release agent in an amount of 0.5 to 50% by mass based on the binder resin. Normally, a toner image is transferred onto a transfer material in a transfer step, and then this toner image is fixed on the transfer material by energy such as heat and pressure to obtain a semi-permanent image. As a fixing method at this time, a hot roll fixing method is generally used, and as described above, if a toner having a weight average particle diameter of 10 μm or less can be used, a very high-definition image can be obtained. When a transfer material such as paper is used, the toner particles having a small diameter enter gaps between fibers of the paper, insufficiently receive heat from the heat fixing roller, and a low-temperature offset is likely to occur. However, by including an appropriate amount of wax as a release agent in the toner of the present invention, it is possible to prevent shaving of the photoreceptor while achieving both high resolution and offset resistance.

Examples of the wax usable in the toner of the present invention include petroleum waxes such as paraffin wax, microcrystalline wax and petrolactam and derivatives thereof, montan wax and derivatives thereof, hydrocarbon waxes and derivatives thereof by the Fischer-Tropsch method, and polyethylene. And natural waxes and derivatives thereof such as polyolefin waxes and their derivatives, carnauba wax and candelilla wax. The derivatives here include oxides, block copolymers with vinyl monomers, and graft-modified products. Furthermore, fatty acids such as higher aliphatic alcohols, stearic acid, and palmitic acid or compounds thereof, acid amide waxes, ester waxes, ketones, hydrogenated castor oil and derivatives thereof, vegetable waxes, and animal waxes can also be used.

Among these wax components, those having a maximum endothermic peak in the range of 40 to 110 ° C. when the temperature is raised, and those having a maximum endothermic peak in the range of 45 to 90 ° C. in the DSC curve measured by the differential scanning calorimeter are preferable. Those having an endothermic peak are more preferred. By having a maximum endothermic peak in the above temperature range, while greatly contributing to low temperature fixing,
The releasability can also be effectively exhibited. If the maximum endothermic peak is less than 40 ° C., the self-cohesive force of the wax component becomes weak, and as a result, the high-temperature offset resistance deteriorates. On the other hand, if the maximum endothermic peak exceeds 110 ° C., the fixing temperature becomes high, and low-temperature offset tends to occur, which is not preferable. Further, when the toner is directly obtained by a polymerization method by performing granulation / polymerization in an aqueous medium, if the maximum endothermic peak temperature is high, problems such as precipitation of a wax component mainly during granulation are not preferred.

The maximum endothermic peak temperature of the wax component is measured according to “ASTM D3418-8”. For the measurement, for example, DSC-7 manufactured by PerkinElmer is used. The temperature correction of the device detection unit uses the melting points of indium and zinc, and the heat quantity correction uses the heat of fusion of indium. An aluminum pan is used as a measurement sample, an empty pan is set as a control, and the measurement is performed at a heating rate of 10 ° C./min.

In the toner of the present invention, the content of the wax component is 0.5 to 50% by mass based on the binder resin.
Is preferably within the range. If the content of the wax component is less than 0.5% by mass, the effect of suppressing low-temperature offset is poor, and if it exceeds 50% by mass, the long-term storability is reduced, and the dispersibility of other toner materials is deteriorated. This leads to deterioration of fluidity of the image and deterioration of image characteristics.

In the present invention, polymerization may be carried out by adding a resin to the monomer system. For example, hydrophilic functional groups such as amino group, carboxylic acid group, hydroxyl group, sulfonic acid group, glycidyl group, and nitrile group which cannot be used because the monomer dissolves in an aqueous suspension to cause emulsion polymerization due to water solubility. When it is desired to introduce the contained monomer components into the toner, the copolymer may be in the form of a random copolymer, a block copolymer, or a graft copolymer of these and a vinyl compound such as styrene or ethylene, or It can be used in the form of polycondensates such as polyesters and polyamides, and polyaddition polymers such as polyethers and polyimines. When such a high molecular polymer containing a polar functional group is coexisted in the toner, the above-mentioned wax component is phase-separated, the encapsulation becomes stronger, and a toner having good offset resistance, blocking resistance, and low-temperature fixability can be obtained. Obtainable. The amount is preferably 1 to 20 parts by mass with respect to 100 parts by mass of the polymerizable monomer. If the amount is less than 1 part by mass, the effect of addition is small, while if it exceeds 20 parts by mass, it becomes difficult to design various physical properties of the polymerized toner. The average molecular weight of the high molecular polymer containing these polar functional groups is 30.
00 or more is preferably used. Molecular weight less than 3000,
In particular, when the molecular weight is 2000 or less, the present polymer tends to concentrate near the surface, so that adverse effects on developability, blocking resistance, and the like are likely to occur, which is not preferable. Further, if a polymer having a molecular weight different from the molecular weight range of the toner obtained by polymerizing the monomer is dissolved and polymerized in the monomer, the molecular weight distribution is wide,
A toner having high offset resistance can be obtained.

The toner of the present invention may contain a charge control agent for stabilizing the charge characteristics. As the charge control agent, a known charge control agent can be used, but a charge control agent having a high charging speed and capable of stably maintaining a constant charge amount is particularly preferable.

Further, when the toner is produced by a direct polymerization method, a charge control agent having a low polymerization inhibitory property and having substantially no solubilized substance in an aqueous dispersion medium is particularly preferable. Specific compounds include salicylic acid, alkyl salicylic acid, dialkyl salicylic acid, naphthoic acid, metal compounds of aromatic carboxylic acids such as dicarboxylic acids, metal salts or metal complexes of azo dyes or azo pigments, and sulfones as negative charge control agents. Polymer type compound having an acid or carboxylic acid group in the side chain, boron compound, urea compound, silicon compound,
Calix arene. Examples of the positive charge control agent include a quaternary ammonium salt, a polymer compound having the quaternary ammonium salt in the side chain, a guanidine compound, a nigrosine compound, and an imidazole compound. These charge control agents are preferably used in an amount of 0.5 to 10 parts by mass based on 100 parts by mass of the polymerizable monomer. However, in the developer related to the image forming method of the present invention, the addition of a charge control agent is not essential, and the toner in the toner is positively utilized by frictionally charging the layer pressure regulating member of the developer and the developer carrier. Need not necessarily include a charge control agent.

The iron oxide used as a magnetic material in the toner of the present invention includes phosphorus, cobalt, nickel,
It may contain an element such as copper, magnesium, manganese, aluminum, or silicon, and contains iron tetroxide or γ-iron oxide as a main component, and may be used alone or in combination of two or more. These iron oxide, BET specific surface area preferably by nitrogen adsorption method is 2~30m ² / g, especially 3~28m ² / g, further Mohs hardness preferably from 5 to 7.

The shape of the iron oxide is octahedral, 6
There are various shapes such as a face, a sphere, a needle, a scale, and the like, and an octahedron, a hexahedron, a sphere, and an amorphous material having a small anisotropy are preferable for increasing the image density. Such a shape can be confirmed by SEM or the like. As the particle size of the iron oxide, in the measurement of the particle size of particles having a particle size of 0.03 μm or more, the volume average particle size is 0.1 to 0.3.
It is preferable that the number of particles having a particle size of 0.03 to 0.1 μm is 40% by number or less.

When an image is obtained from a magnetic toner using iron oxide having an average particle size of less than 0.1 μm, the color of the image shifts to reddish, and the blackness of the image becomes insufficient. It is generally not preferable, for example, the tendency that reddish taste is strongly felt. In addition, since the surface area of the iron oxide increases, the dispersibility decreases, and the energy required during production increases, which is not efficient. Further, the effect of iron oxide as a coloring agent is weakened, and the density of an image may be insufficient, which is not preferable.

On the other hand, if the average particle size of the iron oxide exceeds 0.3 μm, the mass per particle increases, so that the probability of exposure to the toner surface due to the difference in specific gravity with the binder during production increases, It is not preferable because the possibility that the abrasion of the apparatus becomes remarkable increases or the sedimentation stability of the dispersion decreases.

In the toner, 0.1% of the iron oxide was used.
If the number of particles having a particle size of 1 μm or less exceeds 40% by number, the surface area of the iron oxide increases and the dispersibility decreases. It is preferable that the content be 40% by number or less, since the possibility of the occurrence will increase. Furthermore, if it is 30% by number or less,
Since the tendency becomes smaller, it is more preferable.

It should be noted that iron oxide having a particle diameter of less than 0.03 μm receives a small stress during toner production due to a small particle diameter, and thus has a low probability of being exposed to the surface of the toner particles. Furthermore, even if it is exposed on the particle surface, it hardly acts as a leak site, so that there is substantially no problem. Therefore, in the present invention, attention is paid to particles of 0.03 to 0.1 μm, and the number% thereof is defined.

If the number of particles of 0.3 μm or more in the iron oxide exceeds 10% by number, the coloring power is reduced and the image density tends to be reduced. Therefore, it is unfavorably probabilistically difficult to cause the toner particles to be present in the vicinity of the surface of the toner particles and to make each toner particle contain a uniform number. More preferably 5
It is better to be less than the number%.

In the present invention, it is preferable to use one prepared by setting iron oxide production conditions or adjusting the particle size distribution such as pulverization and classification in advance so as to satisfy the above-mentioned particle size distribution conditions. As a classification method, for example, a method using sedimentation separation such as centrifugal separation or a thickener, or a means such as a wet classification device using a cyclone is preferable.

The volume average particle size and the particle size distribution of the iron oxide are determined by the following measuring methods. With the particles sufficiently dispersed, the projected area of each of the 100 iron oxide particles in the field of view was measured with a transmission electron microscope (TEM) at a magnification of 30,000 times, and the measured area of each particle was measured. The equivalent diameter of a circle equal to the projected area was determined as each particle diameter. Further, based on the results, calculation of the volume average particle size and 0.0
The number% of particles of 3 to 0.1 μm and particles of 0.3 μm or more were calculated. The particle size was measured for particles having a particle size of 0.03 μm or more. Further, the particle size can be measured by an image analyzer.

In determining the volume average particle size and the particle size distribution of the iron oxide in the toner particles, the following measurement methods are used.

After sufficiently dispersing the toner particles to be observed in the epoxy resin, the cured product obtained by curing in an atmosphere at a temperature of 40 ° C. for 2 days is used as a flaky sample by a microtome to obtain a transmission electron microscope. In (TEM), the projected area of each of the particle diameters of 100 iron oxides in the field of view was measured with a photograph at a magnification of 10,000 to 40,000 times, and the equivalent diameter of a circle equal to the measured projected area of each particle was determined. It was determined as the particle size of iron oxide. Further, based on the result, 0.03 to
The number% of particles of 0.1 μm and particles of 0.3 μm or more was calculated. Further, the particle size can be measured by an image analyzer.

Further, other coloring agents may be used in addition to iron oxide. Coloring materials that can be used in combination include magnetic or non-magnetic inorganic compounds, known dyes and pigments. Specifically, for example, cobalt, ferromagnetic metal particles such as nickel, or chromium, manganese, copper,
Zinc, aluminum, alloys with rare earth elements, hematite, titanium black, nigrosine dye / pigment, carbon black, phthalocyanine. These may also be used after treating the surface.

The polymerization initiator used in the present invention, which has a half-life of 0.5 to 30 hours during the polymerization reaction, is subjected to the polymerization reaction in an amount of 0.5 to 20% by mass of the polymerizable monomer. In addition, a polymer having a maximum molecular weight of 10,000 to 100,000 can be obtained, and the toner can have desired strength and suitable melting characteristics. Examples of the polymerization initiator include 2,2′-azobis- (2,4-dimethylvaleronitrile) and 2,2 ′
-Azobisisobutyronitrile, 1,1'-azobis (cyclohexane-1-carbonitrile), 2,2'-
Azo or diazo polymerization initiators such as azobis-4-methoxy-2,4-dimethylvaleronitrile and azobisisobutyronitrile; benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxy carbonate, cumene hydroperoxide, ,
Examples include peroxide-based polymerization initiators such as 4-dichlorobenzoyl peroxide and lauroyl peroxide.

In the present invention, a cross-linking agent may be added.
5% by mass.

In the production of a toner by the suspension polymerization method, generally, an iron oxide, a colorant, a release agent, a plasticizer, a binder, a charge control agent,
Components necessary for toner such as a crosslinking agent and other additives,
For example, an organic solvent to reduce the viscosity of the polymer formed in the polymerization reaction, an appropriate dispersing agent, etc., are added as appropriate, and a homogenizer, a ball mill, a colloid mill, and a uniform dissolution or dispersion are performed by a disperser such as an ultrasonic disperser. The used monomer system is suspended in an aqueous medium containing a dispersion stabilizer. At this time, the particle size of the obtained toner particles becomes sharper by using a high-speed disperser such as a high-speed stirrer or an ultrasonic disperser to make the desired toner particle size at once. As for the timing of the addition of the polymerization initiator, it may be added at the same time as the other additives are added to the polymerizable monomer, or may be mixed immediately before being suspended in the aqueous medium. Immediately after granulation and before the initiation of the polymerization reaction, a polymerization initiator dissolved in a polymerizable monomer or a solvent can be added.

After the granulation, stirring may be performed using an ordinary stirrer to such an extent that the particle state is maintained and the floating and settling of the particles are prevented.

In the suspension polymerization method of the present invention, known surfactants and organic / inorganic dispersants can be used as dispersion stabilizers. Among them, inorganic dispersants are unlikely to produce harmful ultrafine powder, and due to their steric hindrance, Since dispersion stability is obtained, even if the reaction temperature is changed, the stability is hardly lost, the washing is easy, and the toner is hardly adversely affected. Examples of such inorganic dispersants include polyvalent metal phosphates such as calcium phosphate, magnesium phosphate, aluminum phosphate and zinc phosphate; carbonates such as calcium carbonate and magnesium carbonate; calcium metasilicate, calcium sulfate and barium sulfate. Inorganic salts; inorganic oxides such as calcium hydroxide, magnesium hydroxide, aluminum hydroxide, silica, bentonite, and alumina.

These inorganic dispersants include the polymerizable monomer 10
It is preferable to use 0.2 to 20 parts by mass alone or in combination of two or more with respect to 0 parts by mass. When a finer toner having an average particle diameter of 5 μm or less is intended, a surfactant of 0.001 to 0.1 parts by mass may be used in combination.

As the surfactant, for example, sodium dodecylbenzene sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate,
Examples include sodium oleate, sodium laurate, sodium stearate, and potassium stearate.

When these inorganic dispersants are used, they may be used as they are, but in order to obtain finer particles, the inorganic dispersant particles can be formed in an aqueous medium. For example, in the case of calcium phosphate, a water-insoluble calcium phosphate can be produced by mixing an aqueous solution of sodium phosphate and an aqueous solution of calcium chloride under high-speed stirring, whereby more uniform and fine dispersion can be achieved. At this time, a water-soluble sodium chloride salt is simultaneously produced as a by-product, but if the water-soluble salt is present in the aqueous medium, the dissolution of the polymerizable monomer in water is suppressed, and the ultrafine toner due to emulsion polymerization is formed. This is more convenient because it hardly occurs. Since it becomes an obstacle when removing the residual polymerizable monomer at the end of the polymerization reaction, it is better to replace the aqueous medium or to desalinate with an ion exchange resin. The inorganic dispersant can be almost completely removed by dissolving with an acid or alkali after completion of the polymerization.

In the polymerization step, the polymerization temperature is 40
The polymerization is carried out at a temperature of at least 50 ° C., generally from 50 to 90 ° C. When the polymerization is carried out in this temperature range, the release agent and waxes to be sealed inside are precipitated by phase separation, and the encapsulation becomes more complete. In order to consume the remaining polymerizable monomer, the reaction temperature is 90 to 90 at the end of the polymerization reaction.
It is possible to increase to 150 ° C.

It is preferable that an inorganic fine powder or a hydrophobic inorganic fine powder is mixed with the toner of the present invention as a fluidity improver. For example, it is preferable to add and use titanium oxide fine powder, silica fine powder, and alumina fine powder, and it is particularly preferable to use silica fine powder.

The inorganic fine powder used for the developer is BET.
Specific surface area according to the measured nitrogen adsorption by law is more than 30 m ² / g, preferably possible especially in the range of 50 to 400 m ² / g give good results.

The fine silica powder used in the present invention may be either a dry method produced by vapor phase oxidation of a silicon halide compound or a dry method called fumed silica and a so-called wet method produced from water glass or the like. Although usable, dry silica having few silanol groups on the surface and inside and having no production residue is preferably used.

Further, the silica fine powder used in the present invention is preferably subjected to a hydrophobic treatment. The hydrophobizing treatment is applied by chemically treating with an organic silicon compound or the like which reacts or physically adsorbs with the silica fine powder. A preferred method is to treat the dry silica fine powder produced by the vapor phase oxidation of the silicon halide compound with a silane coupling agent or simultaneously with the silane coupling agent and an organic silicon compound such as silicone oil. Is mentioned.

Examples of the silane coupling agent used in the hydrophobizing treatment include hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allylphenyl Dichlorosilane, benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane,
Chloromethyldimethylchlorosilane, triorganosilane mercaptan, trimethylsilyl mercaptan, triorganosilyl acrylate, vinyldimethylacetoxysilane, dimethylethoxysilane, dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyldi Siloxane and 1,3-diphenyltetramethyldisiloxane.

Examples of the organosilicon compound include silicone oil. Preferred silicone oils have a viscosity of about 30 to 1,000 mm at 25 ° C.
² / s (cSt), for example, dimethyl silicone oil, methylphenyl silicone oil, α
-Preferred are methylstyrene-modified silicone oil, chlorophenyl silicone oil and fluorine-modified silicone oil.

The silicone oil treatment may be carried out, for example, by mixing silica fine powder treated with a silane coupling agent and silicone oil directly using a mixer such as a Henschel mixer, or adding silicone oil to a base silica. A method of injecting oil may be used. Alternatively, it may be prepared by dissolving or dispersing a silicone oil in an appropriate solvent, mixing with a base silica fine powder, and removing the solvent.

An external additive other than the fluidity improver may be added to the toner of the present invention, if necessary.

For example, fine particles having a primary particle size of more than 30 nm (preferably having a specific surface area of less than 50 m ² / g), more preferably a primary particle size of 50 nm or more (preferably a specific surface area) for the purpose of improving the cleaning property. Is 30m ² /
It is also a preferred embodiment to further add inorganic or organic fine particles having a spherical shape (less than g). For example, it is preferable to use spherical silica particles, spherical polymethylsilsesquioxane particles, and spherical resin particles.

Still other additives, for example lubricant powders such as Teflon® powder, zinc stearate powder, polyvinylidene fluoride powder; or abrasives such as cerium oxide powder, silicon carbide powder, strontium titanate powder;
A caking inhibitor; or a conductivity-imparting agent such as, for example, carbon black powder, zinc oxide powder, tin oxide powder;
Further, organic fine particles and inorganic fine particles of opposite polarity can be added in small amounts as a developing property improver. These additives can also be used after their surfaces are subjected to a hydrophobic treatment.

As described above, the external additive is preferably used in an amount of 0.1 to 5 parts by mass (preferably 0.1 to 3 parts by mass) based on 100 parts by mass of the toner.

In the case of producing the toner of the present invention by a pulverization method, a known method can be used. Known methods include, for example, a binder resin, a magnetic material, a release agent, a charge control agent, and, in some cases, components necessary as a toner such as a colorant and other additives, etc., in a mixer such as a Henschel mixer or a ball mill. After sufficient mixing in a heating roll, kneader, melt kneading using a hot kneader such as an extruder, and disperse other toner materials such as a magnetic material while compatibilizing the resins with each other. After dissolving, solidifying by cooling, and pulverizing, classification and, if necessary, surface treatment are performed to obtain toner particles, and if necessary, fine powder or the like is added and mixed to obtain a developer. Either the classification or the surface treatment may be performed first. In the classification step, it is preferable to use a multi-segment classifier from the viewpoint of production efficiency.

The pulverizing step can be performed using a known pulverizing apparatus such as a mechanical impact type or a jet type. In order to obtain a developer having a specific degree of circularity according to the present invention, it is preferable to further apply heat to pulverize or to perform a supplementary mechanical impact treatment. Further, a hot water bath method in which finely pulverized (classified as necessary) toner particles are dispersed in hot water, a method in which the toner particles pass through a hot air flow, or the like may be used.

As a method for applying a mechanical impact force, there is a method using a mechanical impact type pulverizer such as a Kryptron system manufactured by Kawasaki Heavy Industries and a turbo mill manufactured by Turbo Industries. Also, as in devices such as Hosokawa Micron's Mechano-Fusion System and Nara Machinery's Hybridization System, the toner is pressed against the inside of the casing by centrifugal force with the blades rotating at high speed, and the force such as compressive force and frictional force is applied. A method of applying a mechanical impact force to the toner may be used.

When performing a process of applying a mechanical shock,
It is preferable from the viewpoint of prevention of agglomeration and productivity that the ambient temperature at the time of the treatment is set to a temperature near the glass transition point Tg of the toner (that is, a temperature in the range of ± 30 ° C. of the glass transition point Tg). More preferably, processing at a temperature in the range of ± 20 ° C. of the glass transition point Tg of the toner is particularly effective for improving transfer efficiency.

Further, the toner of the present invention is disclosed in
No. 6,139,945 or the like, a method in which a molten mixture is atomized into air using a disk or a multi-fluid nozzle to obtain a spherical toner, or an aqueous organic solvent which is soluble in a monomer and insoluble in a polymer obtained. A toner is produced using an emulsion polymerization method typified by a dispersion polymerization method in which a toner is directly produced by using a toner, or a soap-free polymerization method in which a toner is produced by directly polymerizing in the presence of a water-soluble polar polymerization initiator. It is also possible to manufacture by the method described above.

When the toner of the present invention is produced by a pulverization method, the binder resin may be, for example, a homopolymer of styrene or a substituted product thereof such as polystyrene and polyvinyl toluene; a styrene-propylene copolymer and a styrene-vinyl toluene copolymer. Copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-acrylic acid Dimethylaminoethyl copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-dimethylaminoethyl methacrylate copolymer, styrene- Vinyl methyl ether copolymer, styrene-vinyl Styrene copolymers such as ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-maleic acid copolymer, and styrene-maleic acid ester copolymer Polymers: polymethyl methacrylate, polybutyl methacrylate, polyvinyl acetate, polyethylene, polypropylene, polyvinyl butyral, silicone resin, polyester resin, polyamide resin, epoxy resin, polyacrylic resin, rosin, modified rosin, tempel resin, phenol resin, Aliphatic or alicyclic hydrocarbon resins, aromatic petroleum resins, paraffin wax, carnauba wax can be used alone or in combination. In particular, styrene-based copolymers and polyester resins are preferred in terms of development characteristics, fixability, and the like.

Next, a developing method using the toner of the present invention will be described.

First, a system in which the toner carrier and the electrostatic image carrier are not in contact will be described.

In the non-contact developing method, the magnetic toner is applied on the toner carrier with a layer thickness smaller than the closest distance (between SD) between the toner carrier and the photoconductor (electrostatic image carrier). Then, development is performed by applying an alternating electric field. That is, the layer is regulated so that the closest gap between the photoconductor and the toner carrier is larger than the toner layer thickness on the toner carrier by the layer thickness regulating member that regulates the magnetic toner on the toner carrier.
At this time, it is particularly preferable that the layer thickness regulating member that regulates the magnetic toner on the toner carrier is an elastic member and is in contact with the toner carrier via the toner from the viewpoint of uniformly charging the magnetic toner. .

Further, the toner carrier is set at 10
It is preferable that the devices are installed facing each other with a separation distance of 0 to 500 μm, and it is more preferable that the devices are installed facing each other with a separation distance of 120 to 500 μm. If the separation distance of the toner carrier from the photoconductor is smaller than 100 μm, the change in the developing characteristic of the toner with respect to the fluctuation of the separation distance becomes large, so that it is difficult to mass-produce an image forming apparatus satisfying stable image quality. . If the separation distance of the toner carrier from the photoconductor is larger than 500 μm, the recoverability of the transfer residual toner to the developing device is reduced, and fog due to poor recovery is likely to occur. In addition, the ability of the toner to follow the latent image on the photoreceptor is reduced, resulting in a reduction in image quality such as a reduction in resolution and a reduction in image density.

In the present invention, 5 to 5
It is preferable that the layers are laminated so as to form a toner layer of 30 g / m ² . If the amount of toner on the toner carrier is less than 5 g / m ^2, it is difficult to obtain a sufficient image density, and the toner layer becomes uneven due to excessive charging of the toner. If the amount of toner on the toner carrier is more than 30 g / m ² , toner scattering is likely to occur.

The surface roughness Ra (JIS center line average roughness) of the toner carrier used in the present invention is 0.2 to 0.2.
It is preferably in the range of 3.5 μm. Ra is 0.2
If it is less than μm, the charge amount on the toner carrier increases, and the developability becomes insufficient. On the other hand, when Ra exceeds 3.5 μm, unevenness occurs in the lamination of the toner on the toner carrier, resulting in uneven density on the image. The surface roughness Ra is 0.5-3.
More preferably, it is in the range of 0 μm.

In the present invention, the surface roughness Ra of the toner carrier is determined by using a surface roughness measuring device (Surfcoder SE-30H, manufactured by Kosaka Laboratory Co., Ltd.) based on JIS surface roughness "JISB 0601". Corresponds to the center line average roughness measured. Specifically, a 2.5 mm portion is extracted from the roughness curve in the direction of the center line as the measurement length a,
The center line of the extracted portion is the X axis, and the direction of the vertical magnification is Y.
When the axis and the roughness curve are represented by y = f (x), the value obtained by the following equation is represented by micrometer (μm).

[0157]

[Outside 2]

Further, since the magnetic toner according to the present invention has a high charging ability, it is preferable to control the total charge amount of the toner during development. The surface of the toner carrier according to the present invention is preferably coated with a resin layer in which conductive fine particles and / or a lubricant are dispersed.

As the conductive fine particles contained in the resin layer covering the surface of the toner carrier, conductive metal oxides such as carbon black, graphite and conductive zinc oxide and metal double oxides may be used alone or in combination of two or more. It is preferable to use them in combination. Examples of the resin in which the conductive fine particles and / or the lubricant are dispersed include a phenol resin, an epoxy resin, a polyamide resin, a polyester resin, a polycarbonate resin, a polyolefin resin, a silicone resin, a fluorine resin, and a styrene resin. Known resins such as resins and acrylic resins are used. Particularly, a thermosetting resin or a photocurable resin is preferable.

In the non-contact developing method, it is preferable that the moving speed of the toner carrier for carrying the toner in the developing step and transporting the toner to the developing section is different from the moving speed of the photosensitive member. By providing such a speed difference, the toner particles and the conductive fine powder can be sufficiently supplied from the toner carrier side to the photoconductor side, and a good image can be obtained.

The surface of the toner carrier for carrying the toner may move in the same direction as the direction of movement of the surface of the photoconductor,
It may be moving in the opposite direction. The speed at that time,
It is preferable that one moves at a speed of 1.02 to 3.0 times that of the other, rather than the moving speed between the surface of the toner carrier and the surface of the photoconductor is constant.

In the developing section, the magnetic toner is applied to the electrostatic latent
AC bias is applied to transfer to image and develop
However, the AC bias at this time is at least a peak.
Electric field strength of two peaks is 3 × 10 ⁶~ 1 × 10⁷V / m
And a frequency of 100 to 5000 Hz is preferable.
New It is also preferable to add a DC bias.
It is a form.

On the other hand, a description will be given of a system in which a toner carrier and an electrostatic image carrier are brought into contact to perform development.

In the contact development method, it is preferable to use reversal development.

Further, it is also a preferable embodiment to use a cleanerless process together, so that the apparatus can be significantly reduced in size. At this time, at the time of development or at the time of blank before and after the development, a bias of a DC or AC component is applied to control the potential so that the development and the remaining toner on the photoreceptor can be collected. And the dark portion potential.

As the toner carrier, it is preferable to use an elastic roller, the surface of which is coated with toner, and which is brought into contact with the surface of the photoreceptor. In this case, the toner is developed by an electric field acting between the photoconductor and the elastic roller facing the photoconductor surface via the toner.
It is necessary to have a potential near the surface and to have an electric field in a narrow gap between the surface of the photoconductor and the surface of the toner carrier. For this reason, it is also possible to use a method in which the elastic rubber of the elastic roller is resistance-controlled in the medium resistance region to keep the electric field while preventing conduction with the photoreceptor surface, or to provide a thin insulating layer on the surface layer of the conductive roller. . Further, it is also possible to adopt a configuration in which a conductive layer is provided on a conductive roller on a conductive roller on which the side facing the photoreceptor surface is covered with an insulating material, or on a side not facing the photoreceptor with an insulating sleeve. It is also possible to use a configuration in which a rigid roller is used as the toner carrier and the photosensitive member is a flexible member such as a belt. The resistance of the elastic roller as a toner carrying member is preferably in the range of 10 ² ~10 ⁹ Ω · cm.

When the surface shape of the toner carrier is set so that its surface roughness Ra (μm) is 0.2 to 3.0, both high image quality and high durability can be achieved. The surface roughness Ra correlates with the toner carrying ability and the toner charging ability.
When the surface roughness Ra of the toner carrier exceeds 3.0, it is not only difficult to reduce the thickness of the toner layer on the toner carrier, but also the chargeability of the toner is not improved, so that an improvement in image quality cannot be expected. . By setting the ratio to 3.0 or less, the toner carrying capacity on the surface of the toner carrier is suppressed, the toner layer on the toner carrier is made thinner, and the number of times of contact between the toner carrier and the toner increases. Since the chargeability of the toner is also improved, the image quality is synergistically improved. On the other hand, when the surface roughness Ra is 0.2
If it is smaller, it becomes difficult to control the amount of toner coating.

In the contact developing method, the peripheral speed of the photosensitive member may be rotated in the same direction as the photosensitive member, or may be rotated in the opposite direction. When the rotation is in the same direction, the peripheral speed of the toner carrier is set to 1.05 to 3.
It is preferable to set so as to be 0 times.

If the peripheral speed of the toner carrier is less than 1.05 times the peripheral speed of the photoconductor, the effect of stirring the toner on the photoconductor becomes insufficient, and good image quality cannot be expected.
Also, when developing an image that requires a large amount of toner over a large area, such as a solid black image, the amount of toner supplied to the electrostatic latent image is insufficient and the image density is reduced. The higher the peripheral speed ratio, the greater the amount of toner supplied to the developing site, the more frequently the toner is attached to and detached from the latent image, and unnecessary portions are collected and added to necessary portions. Thus, an image faithful to the latent image can be obtained. However, if the peripheral speed ratio exceeds 3.0, on the other hand, in addition to the various problems caused by the excessive charging of the toner as described above (image density reduction due to excessive toner charge-up, etc.), mechanical Deterioration of the toner due to stress and sticking of the toner to the toner carrier occur and accelerate, which is not preferable.

Next, the charging step will be described.

In the present invention, a non-contact charging step such as a charging step using a charging device using corona discharge may be used, but a contact charging method in which a charging member is brought into contact with a photosensitive member is a preferable charging method. . In this case, it is preferable to use a charging roller as the contact charging member.

[0172] As a preferable process condition when the charging roller is used, the contact pressure of the roller is 4.9 to 490.
At N / m (5 to 500 g / cm), a DC voltage or a DC voltage with an AC voltage superimposed thereon is used. When using a DC voltage with an AC voltage superimposed, the AC voltage =
Preferably, 0.5-5 kVpp, AC frequency = 50-5 kHz, DC voltage = ± 0.2-5 kV.

Other charging means include a method using a charging blade and a method using a conductive brush. Also when these contact charging means are used, there is an effect that a high voltage becomes unnecessary and generation of ozone is reduced.

As the material of the charging roller and the charging blade as the contact charging means, conductive rubber is preferable, and a release coating may be provided on the surface thereof. As the release coating, a nylon resin, PVdF (polyvinylidene fluoride), PVdC (polyvinylidene chloride), or a fluoroacrylic resin can be used.

Next, the transfer step will be described.

In the present invention, a non-contact transfer step such as a transfer step using a transfer device using corona discharge may be used, but preferably, the transfer means is brought into contact with the photoreceptor via a transfer material to perform the transfer. Is a contact transfer method.

The contact pressure of the transfer means is a linear pressure of 2.9N.
/ M (3 g / cm) or more, more preferably 19.6 N / m (20 g / cm) or more.
If the linear pressure as the contact pressure is less than 2.9 N / m (3 g / cm), it is not preferable because the transfer of the transfer material and the occurrence of transfer failure tend to occur.

As the transfer means in the contact transfer step, an apparatus having a transfer roller or a transfer belt is used. FIG. 5 shows an example of the configuration of the transfer roller. The transfer roller 34 includes at least the core metal 34 a and the conductive elastic layer 34.
b, and the conductive elastic layer has a volume resistance of 10 ⁶ to 10 such as urethane or EPDM in which a conductive material such as carbon is dispersed.
It is made of an elastic body of about ¹⁰ Ωcm, and a transfer bias is applied by a transfer bias power supply 35.

Next, the photosensitive member used in the present invention will be described below.

As the photosensitive member, a-Se, CdS, Zn
A photosensitive drum or a photosensitive belt having a photoconductive insulating material layer such as O ₂ , OPC (organic photoreceptor) and a-Si is preferably used.

In particular, in the present invention, it is preferable to use a photoreceptor whose surface is mainly composed of a polymer binder. For example, when a protective film (protective layer) mainly composed of a resin is provided on an inorganic photoreceptor such as selenium or amorphous silicon, or a charge transport layer of a function-separated organic photoreceptor is composed of a charge transport material and a resin. There is a case where a surface layer is provided, and a case where a protective layer mainly composed of a resin is provided on the surface layer. It is preferable that these surface layers (or protective layers) have releasability. As means for actually providing releasability, a resin having a low surface energy is used for the resin itself constituting the film, Add additives that impart water and lipophilicity, disperse materials with high release properties into powder,
Means and the like. Examples include introducing a functional group such as a fluorine-containing group and a silicone-containing group into the structure of the structural unit of the resin. Examples of additives that impart water repellency and lipophilicity include surfactants. Examples of the material having a high releasability include compounds containing a fluorine atom, that is, polytetrafluoroethylene, polyvinylidene fluoride, and carbon fluoride.

By these means, the contact angle of the surface of the photoreceptor with water can be 85 degrees or more, and the transferability of the toner and the durability of the photoreceptor can be further improved. The contact angle of the photoreceptor surface with water is preferably 90 degrees or more. In the present invention, among the above means (1) to (4), it is preferable to disperse the fluororesin in the outermost surface layer of the releasable powder as described above, and the releasable powder may be polytetrafluoroethylene. It is particularly preferred to use

In order to incorporate these powders on the surface, a layer in which a releasable powder is dispersed in a binder resin is provided on the outermost surface of the photoreceptor, or the photoreceptor itself is mainly composed of resin. If the organic photoreceptor is used, a release powder may be dispersed in the uppermost layer without providing a new surface layer. The amount of release powder added is based on the total amount of the surface layer.
It is preferably from 1 to 60% by mass, more preferably from 2 to 50% by mass. If the amount of the releasable powder is less than 1% by mass, the effect of improving the transferability of the toner and the durability of the photoreceptor is insufficient. If the amount exceeds 60% by mass, the strength of the protective film is reduced,
This is not preferable because the amount of light incident on the photosensitive member is significantly reduced.

In the present invention, the contact charging method in which the charging means is brought into contact with the photoreceptor by the charging means is a preferable charging method. However, the photosensitive means is more sensitive than the method by corona discharge or the like in which the charging means does not come into contact with the photoreceptor. Since the load on the body surface is large, providing a protective layer (protective film) on the surface of the photoreceptor has a remarkable effect of improving the durability, and is one of preferred application forms.

In the present invention, a contact charging method,
Since it is preferable to apply the contact transfer method, the diameter is 5
It is particularly effectively used for an image forming apparatus having a photosensitive member having a small diameter of 0 mm or less. That is, when the diameter of the photoreceptor used for image formation is small, the curvature for the same linear pressure is large, and the pressure is likely to be concentrated at the contact portion. Although it is considered that the same phenomenon occurs in the belt photoreceptor, the present invention has a curvature radius of 25 mm at the transfer portion.
The present invention is also effective for the following image forming apparatuses.

One preferred embodiment of the photosensitive member used in the present invention will be described below.

Examples of the conductive substrate include metals such as aluminum and stainless steel, aluminum alloys, plastics having a coating layer of indium oxide-tin oxide alloy, paper impregnated with conductive particles, plastics, and plastics having a conductive polymer. Are used.

On these conductive substrates, improvement of adhesiveness of the photosensitive layer, improvement of coating property, protection of the substrate, coating of defects on the substrate, improvement of charge injection from the substrate, and improvement of electrical properties of the photosensitive layer are described. An undercoat layer may be provided for the purpose of protection against breakage and the like.
The undercoat layer is made of polyvinyl alcohol, poly-N-vinylimidazole, polyethylene oxide, ethyl cellulose, methyl cellulose, nitrocellulose, ethylene-
It is formed of a material such as acrylic acid copolymer, polyvinyl butyral, phenol resin, casein, polyamide, copolymerized nylon, glue, gelatin, polyurethane, and aluminum oxide. The thickness of the undercoat layer is usually
It is 0.1 to 10 μm, preferably about 0.1 to 3 μm.

The charge generation layer is made of an azo pigment, a phthalocyanine pigment, an indigo pigment, a perylene pigment, a polycyclic quinone pigment, a squarylium dye, a pyrylium salt, a thiopyrylium salt, a triphenylmethane dye, selenium,
A charge generation material such as an inorganic material such as amorphous silicon is dispersed in a suitable binder and coated or formed by vapor deposition. As the binder, for example, a polycarbonate resin, a polyester resin, a polyvinyl butyral resin, a polystyrene resin, an acrylic resin, a methacrylic resin, a phenol resin, a silicone resin, an epoxy resin, and a vinyl acetate resin are exemplified. Any binder can be selected. The amount of the binder contained in the charge generation layer is preferably 80% by mass or less, more preferably 0 to 60% by mass, based on the whole charge generation layer. Further, the thickness of the charge generation layer is preferably 5 μm or less, particularly 0.05 to 2 μm.
m is preferred.

The charge transport layer has a function of receiving charge carriers from the charge generation layer in the presence of an electric field and transporting them. The charge transporting layer is formed by dissolving a charge transporting substance in a solvent together with a binder resin if necessary, and applying the solution. The thickness of the charge generation layer is generally 5 to 40 μm.
m. As the charge transport substance, biphenylene, anthracene, pyrene, a polycyclic aromatic compound having a structure such as phenanthrene, a nitrogen-containing cyclic compound such as indole, carbazole, oxadiazole, and pyrazoline, a hydrazone compound, Examples include styryl compounds, selenium, selenium-tellurium, amorphous silicon, and cadmium sulfide.

As the binder resin for dispersing these charge transporting substances, polycarbonate resin, polyester resin, polymethacrylate, polystyrene resin,
Acrylic resin, resin such as polyamide resin, poly-N-
Organic photoconductive polymers such as vinyl carbazole and polyvinyl anthracene are exemplified.

Further, a protective layer may be further provided as a surface layer. As the resin of the protective layer, polyester, polycarbonate, acrylic resin, epoxy resin, phenol resin, or a curing agent of these resins alone or
It can be used in combination of more than one kind.

In addition, conductive fine particles may be dispersed in the resin of the protective layer. Examples of the conductive fine particles include metals and metal oxides, preferably, zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, tin oxide-coated titanium oxide, tin-coated indium oxide, and antimony. Ultrafine particles of coated tin oxide and zirconium oxide may be mentioned. These conductive fine particles may be used alone or in combination of two or more. Generally, when particles are dispersed in the protective layer, it is necessary that the particle diameter of the particles is smaller than the wavelength of the incident light in order to prevent scattering of the incident light by the dispersed particles, and the particles are dispersed in the protective layer in the present invention. The conductive fine particles preferably have a particle size of 0.3 μm or less. The content of the conductive fine particles in the protective layer is preferably from 2 to 90% by mass, more preferably from 5 to 80% by mass, based on the total weight of the protective layer. The thickness of the protective layer is preferably from 0.1 to 10 μm, more preferably from 1 to 7 μm.

The application of the surface layer can be carried out by spray coating, beam coating or permeation (dipping) coating of the resin dispersion.

Next, the image forming method of the present invention will be specifically described with reference to the drawings.

In the image forming apparatus shown in FIG. 1, reference numeral 100 denotes a photosensitive drum around which a primary charging roller 117, a developing device 140, a transfer charging roller 114, a cleaner 116,
A register roller 124 and the like are provided. Then, the photoconductor 100 is charged to, for example, −700 V by the primary charging roller 117. (The applied voltage is AC voltage-2.
0 k Vpp, DC voltage -700 Vdc) and
The photoconductor 100 is exposed by irradiating the photoconductor 100 with a laser beam 123 by a laser generator 121. Photoconductor 1
The electrostatic latent image on 00 is developed with a one-component magnetic developer by a developing device 140, and is transferred onto a transfer material by a transfer roller 114 that is in contact with the photoconductor via the transfer material. The transfer material bearing the toner image is carried to a fixing device 126 by a conveyor belt 125 or the like, and is fixed on the transfer material. Further, the toner left partially on the photoconductor is cleaned by the cleaning unit 116. As shown in FIG. 2, the developing device 140 is a cylindrical toner carrier 102 made of a non-magnetic metal such as aluminum or stainless steel.
(Hereinafter referred to as a developing sleeve), and the photosensitive member 100
The gap between the photoconductor and the developing sleeve 102 is maintained at about 300 μm by a sleeve / photosensitive member gap holding member (not shown) or the like. A magnet roller 104 is provided in the developing sleeve.
Are fixed and disposed concentrically with the developing sleeve 102. However, the developing sleeve 102 is rotatable. The magnet roller 104 is provided with a plurality of magnetic poles as shown in the drawing, where S1 is development, N1 is toner toner amount regulation,
S2 affects the taking-in / conveyance of the toner, and N2 affects the prevention of the blowing of the toner. The toner is applied to the toner application roller 1
By 41, it is applied to the developing sleeve 102, adhered and transported. An elastic blade 103 is provided as a member for regulating the amount of toner conveyed.
The amount of toner conveyed to the developing area is controlled by the contact pressure of the developing sleeve 102 with respect to the developing sleeve 102. In the developing area, a DC and AC developing bias is applied between the photoconductor 100 and the developing sleeve 102, and the developer on the developing sleeve flies on the photoconductor 100 according to the electrostatic latent image to become a visible image. .

Next, the image forming method of the present invention will be described with reference to FIGS.
This will be described below with reference to FIG.

FIG. 3 schematically shows an image forming apparatus using a cleanerless process, in which 40 is a developing device, 1 is a photoreceptor, 27 is a transfer target (transfer material) such as paper, and 14 is a transfer member. Reference numeral 26 denotes a pressure roller for fixing, reference numeral 28 denotes a heating roller for fixing, and reference numeral 17 denotes a primary charging member for directly charging the photosensitive member 1 by contacting the same. A bias power source 31 is connected to the primary charging member 17 so as to uniformly charge the surface of the photoconductor 1.

The developing device 40 contains the toner 42, and includes the toner carrier 4 that rotates in the direction of the arrow when in contact with the photosensitive member 1. Further, the developing blade 43 and the toner 42 for regulating the amount of toner and applying the charge are transferred to the toner carrier 4.
And an application roller 41 that rotates in the direction of the arrow to apply charge to the toner by friction with the toner carrier 4.
It also has. The toner carrier 4 has a developing bias power source 3
3 are connected. A bias power supply 32 is also connected to the application roller 41, and the voltage is set to a negative side of the developing bias when using a negatively charged toner, and to a positive side than the developing bias when using a positively charged toner. Is done.

The transfer member 14 is connected to a transfer bias power supply 34 having a polarity opposite to that of the photosensitive member 1.

Here, the length of the contact portion between the photosensitive member 1 and the toner carrier 4 in the rotational direction, that is, the so-called development nip width is preferably 0.2 to 8.0 mm. If the thickness is less than 0.2 mm, a sufficient image density cannot be obtained due to an insufficient development amount, and the transfer residual toner cannot be sufficiently recovered. If the thickness exceeds 8.0 mm, the supply amount of the toner becomes excessive, fog suppression is likely to be deteriorated, and abrasion of the photoconductor 1 is adversely affected.

As the toner carrier 4, a so-called elastic roller having an elastic layer on its surface is preferably used.

The hardness of the material of the elastic layer used is as follows.
Those having a temperature of 20 to 65 degrees (JIS A) are preferably used.

The resistance of the toner carrier 4 is preferably in the range of about 10 ² to 10 ⁹ Ω · cm in terms of volume resistance. If it is lower than 10 ² Ω · cm, for example, if there is a pinhole on the surface of the photoreceptor 1, an overcurrent may flow. On the other hand, when it is higher than 10 ⁹ Ω · cm, the toner is liable to be charged up due to frictional charging, and the image density is liable to be reduced.

The toner coat amount on the toner carrier 4 is
0. 12.0 mg / cm ² is preferred. 0. lmg / c
If less than m ^2, it is difficult to obtain a sufficient image density,
When the amount is more than mg / cm ^2, it becomes difficult to uniformly triboelectrically charge all the individual toner particles, which causes deterioration of fog suppression. Furthermore, 0.2 to 1.2 mg / cm ²
Is more preferred.

The toner coating amount is controlled by the developing blade 143. The developing blade 143 is in contact with the toner carrier 104 via the toner layer. The contact pressure at this time is preferably in the range of 5 to 50 g / cm. 5g
If it is less than / cm, it is difficult to control the amount of toner coating and also to make uniform triboelectric charging difficult, which causes deterioration of fog suppression and the like. On the other hand, if it is more than 50 g / cm, the toner particles receive an excessive load, so that deformation of the particles, fusion of the toner to the developing blade 143 or the toner carrier 104 and the like are apt to occur, which is not preferable.

As the toner coating amount regulating member, a metal blade or a roller may be used in addition to the elastic blade for press-applying the toner.

For the elastic regulating member, it is preferable to select a material of a triboelectric series suitable for charging the toner to a desired polarity. Silicone rubber, urethane rubber, NB
Rubber elastic materials such as R, synthetic resin elastic materials such as polyethylene terephthalate, and metal elastic materials such as stainless steel, copper, and phosphor bronze can be used. Further, a composite thereof may be used.

When durability is required for the elastic regulating member and the toner carrier, it is preferable that a metal elastic body is bonded or coated with resin or rubber so as to contact the sleeve contact portion.

Further, an organic substance or an inorganic substance may be added to the elastic regulating member, may be melt-mixed, or may be dispersed. For example, metal oxides, metal powders, ceramics, carbon allotropes, whiskers, inorganic fibers, dyes, pigments,
By adding a surfactant, the chargeability of the toner can be controlled. In particular, when the elastic body is a molded body such as rubber or resin, silica, alumina, titania, tin oxide,
It is also preferable to include a metal oxide fine powder such as zirconia and zinc oxide, carbon black, and a charge control agent generally used for toner.

Further, by applying a DC electric field and / or an AC electric field to the regulating member, the uniform thin layer coating property and the uniform charging property are further improved due to the loosening action to the toner, and a sufficient image density is achieved. And high quality images can be obtained.

In FIG. 3, the primary charging member 17 uniformly charges the photosensitive member 1 rotating in the direction of the arrow.

[0213] The primary charging member used here is a charging roller basically composed of a central metal core 17b and a conductive elastic layer 17a formed on the outer periphery thereof. Charging roller 17
Is pressed against the entire surface of the electrostatic latent image carrier with a pressing force, and is driven to rotate as the photoconductor 1 rotates.

When the charging roller 117 is used, preferable process conditions include a contact pressure of the roller of 5 to 500 g.
/ Cm, and the applied voltage may be a DC voltage or a DC voltage with an AC voltage superimposed thereon, and is not particularly limited. In the present invention, an applied voltage of only a DC voltage is preferably used. ± 0.2 as voltage value
Used in the range of ± 5 kV.

Other charging means include a method using a charging blade and a method using a conductive brush. These contact charging means, compared to non-contact corona charging,
There are effects that a high voltage becomes unnecessary and generation of ozone is reduced. The material of the charging roller and the charging blade as the contact charging means is preferably a conductive rubber, and a release coating may be provided on the surface thereof. As the release coating, a nylon resin, PVDF (polyvinylidene fluoride), or PVDC (polyvinylidene chloride) can be used.

Following the primary charging step, an electrostatic latent image corresponding to the information signal is formed on the photosensitive member 1 by exposure 23 from the light emitting element 21, and the electrostatic latent image is Is developed into a visible image. further,
In the image forming method of the present invention, in particular, by combining with a developing system that has formed a digital latent image on the photoreceptor,
Since the latent image is not disturbed, the dot latent image can be developed faithfully. Next, the visible image is transferred onto the transfer member 27 by the transfer member 14 having the core member 14a and the conductive elastic layer 14b having the outer periphery formed thereon, and the transfer toner 29 is further transferred to the transfer member 27. At the same time, the pressure roller for fixing 26 and the pressure roller for fixing 2
8 and is fixed by being conveyed to a fixing device having a fixed image forming unit 8 and a permanent image. In addition, as the heating and pressing fixing means, a heating roller having a built-in heating element such as a halogen heater described here and a heating roller method having a basic configuration of an elastic pressing roller pressed against the heating roller with a pressing force are used. A method of fixing by heating with a heater via a film is also used.

On the other hand, the untransferred toner remaining on the photoreceptor 1 without being transferred passes between the photoreceptor 1 and the primary charging member 17, reaches the developing nip again, and is developed by the toner carrier 4. Collected in the vessel 40.

The method for measuring various physical property data in the present invention will be described in detail below.

(1) The ratio of the iron element content (B) to the carbon element content (A) present on the toner surface (B /
A) The ratio (B / A) of the iron element content (B) to the carbon element content (A) present on the toner surface in the present invention.
Was calculated by performing surface composition analysis by ESCA (X-ray photoelectron spectroscopy).

In the present invention, the ESCA apparatus and measurement conditions are as follows. Equipment used: PHI (Physical Electr)
onics Industries, Inc. 1)
600S type X-ray photoelectron spectrometer Measurement conditions: X-ray source MgKα (400 W) Spectral area 800 μmφ

In the present invention, the surface atomic concentration (atomic%) was calculated from the measured peak intensities of the respective elements using a relative sensitivity factor provided by PHI.

A toner was used as a measurement sample. When an external additive was added to the toner, the toner was washed with a solvent that does not dissolve the toner such as isopropanol, and the external additive was removed. The measurement will be performed later.

(2) Average Circularity of Toner The circularity in the present invention is used as a simple method for quantitatively expressing the shape of a particle. In the present invention, flow type particle image analysis manufactured by Toa Medical Electronics Co., Ltd. Device FPIA-100
The particle shape is measured using 0, and the circularity is determined by the following equation. Further, as shown by the following equation, the value obtained by dividing the total sum of the measured circularities of all the particles by the total number of particles is defined as the average circularity.

[0224]

[Outside 3]

[0225] The measuring device "FPIA-1000" used in the present invention calculates the circularity of each particle, and then calculates the circularity.
In calculating the average circularity, the circularity obtained is 0.400 or more and less than 0.410, and 0.410 or more and less than 0.420 in the circularity of 0.400 to 1.000 at 0.010 intervals depending on the circularity obtained. A calculation method is used in which the range is divided into 61 divided ranges such as 0.990 or more and less than 1.000 and 1.000, and the average circularity is calculated using the center value and frequency of the division points.

The error between each value of the average circularity calculated by this calculation method and each value of the average circularity calculated by the above-described calculation formula directly using the circularity of each particle is extremely small, and Therefore, in the present invention, the above-described calculation formula that directly uses the circularity of each particle is used in the present invention for data handling reasons such as shortening of calculation time and simplification of calculation formula. Utilizing the concept, a partially modified such calculation method is used.

The degree of circularity in the present invention is an index indicating the degree of unevenness of particles, and is 1. if the particles are perfectly spherical.
000, and the degree of circularity becomes smaller as the surface shape becomes more complicated.

As a specific method of measuring the circularity, 10 m of water containing about 0.1 mg of a nonionic surfactant was dissolved.
Approximately 5 mg of the toner is dispersed in 1 l to prepare a dispersion, and the dispersion is irradiated with ultrasonic waves (20 kHz, 50 W) for 5 minutes to make the concentration of the dispersion 5000 to 20000 particles / μl. The circularity distribution of particles having an equivalent circle diameter of 3 μm or more is measured.

The outline of the measurement is described in the catalog of FPIA-1000 (June 1995 edition) issued by Toa Medical Electronics Co., Ltd., the operation manual of the measuring apparatus, and Japanese Patent Application Laid-Open No. 8-136.
No. 439, which is as follows.

The sample dispersion liquid is passed through a flow path (spread along the flow direction) of a flat and flat transparent flow cell (about 200 μm thick). The strobe and the CCD camera are mounted on the flow cell so as to be positioned on opposite sides of the flow cell so as to form an optical path that intersects with the thickness of the flow cell. While the sample dispersion is flowing, strobe light is applied at 1/30 second intervals to obtain an image of the particles flowing through the flow cell, so that each particle has a certain range parallel to the flow cell. Photographed as a two-dimensional image. The diameter of a circle having the same area is calculated as the equivalent circle diameter from the area of the two-dimensional image of each particle. The circularity of each particle is calculated from the projected area of the two-dimensional image of each particle and the perimeter of the projected image using the above-described circularity calculation formula.

(3) Particle Size Distribution of Toner A Coulter Counter TA-II type (manufactured by Coulter Inc.) was used as a measuring device, and an interface (manufactured by Nikkaki) for outputting the number distribution and volume distribution and a CX-1 personal computer (Canon) Made), and the electrolyte is 1
A 1% NaCl aqueous solution is prepared using graded sodium chloride. For example, ISOTON R-II (manufactured by Coulter Scientific Japan) can be used. As a measuring method, 0.1 to 5 ml of a surfactant (preferably an alkylbenzene sulfonate) is added as a dispersing agent to 100 to 150 ml of the aqueous electrolytic solution, and the measurement sample is added to
Add 20 mg. The electrolytic solution in which the sample was suspended was subjected to a dispersion treatment for about 1 to 3 minutes with an ultrasonic disperser, and the above-mentioned Coulter Counter TA-II type was used as an aperture of 100 μm.
Using an aperture to measure the volume and number of toner
Calculate the volume distribution and number distribution of 〜40 μm particles.
Then, a weight average weight D4 (the median value of each channel is a representative value for each channel) obtained from the number average particle diameter (D1) volume distribution, and a weight of 12.7 μm or more obtained from the volume distribution. Find the distribution.

[0232]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Production Examples and Examples, but this does not limit the present invention in any way. Parts or% described in Examples are parts by mass or% by mass.

(Production Example 1 of Hydrophobic Iron Oxide) A 1.0 to 1.1 equivalent of caustic soda solution with respect to iron ions is mixed with an aqueous ferrous sulfate solution, and an aqueous solution containing ferrous hydroxide is added. Prepared.

While maintaining the aqueous solution at pH 9, air was blown therein to perform an oxidation reaction at 80 to 90 ° C. to prepare a slurry liquid for generating seed crystals.

Next, the slurry was added to the initial alkali content (sodium component of caustic soda) of 0.9 to 1.
After adding an aqueous solution of ferrous sulfate so as to be 2 equivalents, the slurry liquid is maintained at pH 8, and the oxidation reaction is promoted while blowing air. At the end of the oxidation reaction, the pH is adjusted to about 6, and the silane coupling is performed. agent _{[n-C 4 H 9 Si} (OCH 3) 3] was added 0.5 parts per 100 parts of magnetic iron oxide, were thoroughly stirred. The produced hydrophobic iron oxide particles were washed, filtered and dried by a conventional method, and then the aggregated particles were crushed to obtain hydrophobic iron oxide 1. Table 1 shows the physical properties of hydrophobic iron oxide 1.

(Production Example 2 of Hydrophobic Iron Oxide) The oxidation reaction was carried out in the same manner as in Production Example 1, and the magnetic iron oxide particles formed after the oxidation reaction were washed, filtered, taken out, and dried in another water without drying. After the re-dispersion, the pH of the re-dispersed liquid is adjusted, and the silane coupling agent [n-C ₆ H ₁₃ Si
(OCH ₃ ) ₃ ] was added to perform a coupling treatment. The generated hydrophobic iron oxide particles are washed by an ordinary method,
After filtration and drying, the aggregated particles were slightly crushed to obtain hydrophobic iron oxide 2.

(Production Example 3 of Hydrophobic Iron Oxide) Hydrophobic iron oxide ₃ was prepared in the same manner as in Production Example 2 except that nC ₁₀ H ₂₁ Si (OCH ₃ ) ₃ was used as a silane coupling agent.
I got

(Production Example 4 of Hydrophobic Iron Oxide) A hydrophobic iron oxide 4 was obtained in the same manner as in Production Example 2 except that γ-glycidyltrimethoxysilane was used as a silane coupling agent.

(Production Example 5 of Hydrophobic Iron Oxide) A caustic soda solution in an amount of 1.0 to 1.1 equivalents to iron ions was mixed with an aqueous ferrous sulfate solution, and an aqueous solution containing ferrous hydroxide was added. Prepared.

While maintaining the pH of the aqueous solution at 9, the air was blown therein to carry out an oxidation reaction at 80 to 90 ° C. to prepare a slurry for producing seed crystals.

Next, the slurry was added to the initial amount of alkali (sodium component of caustic soda) in a range of 0.9 to 1.0.
After adding an aqueous solution of ferrous sulfate so as to be 2 equivalents, the slurry liquid was maintained at pH 8, the oxidation reaction was promoted while blowing air, and the pH was adjusted at the end of the oxidation reaction to terminate the oxidation reaction. The generated particles are washed, filtered, and dried by a conventional method, and then the aggregated particles are crushed to obtain iron oxide particles a.
I got A silane coupling agent [n-C ₆ H _13] obtained by diluting the obtained iron oxide particles a with methanol in the gas phase by a factor of 10
Si (OCH ₃ ) ₃ ] (adjusted so that the coupling agent becomes 0.5 part with respect to 100 parts of iron oxide) to obtain hydrophobic iron oxide 5.

(Production Example 6 of Hydrophobic Iron Oxide) The iron oxide particles a obtained in Production Example 5 of hydrophobic iron oxide were dispersed in water,
The pH of the aqueous iron oxide dispersion was adjusted, 0.5 part of a silane coupling agent [nC ₆ H ₁₃ Si (OCH ₃ ) ₃ ] was added, and the mixture was thoroughly mixed and stirred. The formed hydrophobic iron oxide particles were washed, filtered and dried by a conventional method, and then the aggregated particles were crushed to obtain hydrophobic iron oxide 6.

Table 1 shows the physical properties of the above-mentioned hydrophobic iron oxides 2 to 6.

[0244]

[Table 1]

Next, the following Examples 1 to 6 and Comparative Examples 1 to
The image forming apparatus used in No. 4 will be described.

A commercially available laser beam printer LBP-SX (manufactured by Canon Inc.) which performs development by a non-contact development method was used as modified below. That is, the toner layer thickness regulating member in the process cartridge portion was changed to a urethane rubber elastic blade, a toner application roller and a cleaning magnet roller were installed, and the magnet contained in the toner carrier (developing sleeve) 15 was removed. An LBP printer was used.

The image forming conditions are shown below.

FIG. 6 illustrates the alternating voltage used. V _dc represents the dc supply voltage, V _d the dark portion potential on the electrostatic latent image bearing member, the V _L respectively represent the light portion potential.
f is the frequency of the alternating voltage, the V _pp shows the voltage between the alternating voltage peak.

[0249] to form an electrostatic latent image V _d as -600 V, to set the gap (300 [mu] m) in a non-contact a developer layer on the developing sleeve 15 and the photosensitive drum 3, the developing sleeve 15
To the AC bias (f =
3200 Hz V _pp = 1800 V) and a DC bias (V _dc = −400 V) were applied, and _VL was set at −150 V to perform image display.

The peripheral speed ratio of the developing sleeve to the photosensitive drum was set to 200%.

Example 1 451 parts by mass of a 0.1 mol / l aqueous solution of Na ₃ PO ₄ were added to 709 parts by mass of ion-exchanged water and heated to 60 ° C., and then a 1.0 mol / l aqueous solution of CaCl ₂ 67 was added. 0.7 parts by mass was gradually added to obtain an aqueous medium containing Ca ₃ (PO ₄ ) ₂ .

On the other hand, 82 parts of styrene 18 parts of n-butyl acrylate 5 parts of polyester resin 2 parts of negative charge control agent (Fe compound of monoazo dye system) 2 parts of hydrophobic iron oxide 1 100 parts (Mitsui Miike Kakoki Co., Ltd.) to uniformly disperse and mix.

This monomer composition was heated to 60 ° C., and 20 parts of an ester wax (mp. 70 ° C.) was mixed and dissolved therein, and the polymerization initiator 2,2′-azobis (2,4- 8 parts by mass of dimethylvaleronitrile [t _1/2 = 140 minutes, at 60 ° C.] and dimethyl-2,2′-azobisisobutyrate [t _1/2 = 270 minutes, 60 ° C .; t _{1 / 2} = 8
0 minutes, at 80 ° C.].

The above-mentioned polymerizable monomer system was charged into the above aqueous medium, and the mixture was heated at 10,000 rpm with a TK homomixer (Tokusai Kika Kogyo Co., Ltd.) at 60 ° C. in an N ₂ atmosphere.
The mixture was stirred for 5 minutes and granulated. Thereafter, the mixture was reacted at 60 ° C. for 1 hour while stirring with a paddle stirring blade. After that, the liquid temperature was 80 ° C.
The stirring was continued for another 10 hours. After the completion of the reaction, the suspension was cooled, and hydrochloric acid was added to dissolve Ca ₃ (PO ₄ ) ₂ , followed by filtration, washing with water and drying to obtain toner particles.

100 parts of the toner particles and 1.4 parts of a hydrophobic silica fine powder having a BET specific surface area of 120 m ² / g after the hexamethyldisilazane treatment and the silicone oil treatment were mixed with a Henschel mixer (Mitsui The mixture was mixed with Miike Kakoki Co., Ltd., and toner A (weight average particle size 6.2 μm) was mixed.
m) was prepared.

Here, the dispersion state of the hydrophobic iron oxide inside the toner A particles was evaluated by observing the tomographic plane of the toner particles using a transmission electron microscope (TEM).

As a specific evaluation method by TEM,
The determination was performed in the same manner as in the case of determining the volume average particle size and the particle size distribution of iron oxide in the toner particles described above.

The specific evaluation of the state of dispersion of the hydrophobic iron oxide inside the toner particles was performed as follows. A tomographic plane having a diameter of ± 10% of the number average particle diameter of the toner is extracted, and a similar figure having a half diameter is written by making the center of the tomographic plane the same (the area of the similar figure is 1% of the area of the particle tomographic plane). / 4).

Next, in the particle tomographic plane (including in similar figures)
The number of the hydrophobic iron oxide powder having a particle size of 0.03 μm or more is counted, and the number is defined as a. Similarly, the number of hydrophobic iron oxide powder having a size of 0.03 μm or more existing in the similar figure is counted, and the number is set as b. The ratio b / a is calculated for a and b thus obtained.

As the value of the ratio b / a approaches 面積, which is the area ratio of each surface, the hydrophobic iron oxide powder has the same amount from the center of the toner particles to the vicinity of the surface layer.
It means that the dispersion state of the hydrophobic iron oxide in the toner particles is uniform, and if the value of b / a is in the range of 3/8 to 1/5, it can be said that almost satisfactory dispersion is achieved. .

When b / a was calculated for toner A,
It was about 1/4, and it was found that the dispersion state of the hydrophobic iron oxide in the toner particles was very uniform.

Using the toner A under normal temperature and normal humidity environment (23
(° C., 65% RH) 5000 images were printed.
As a result, a good image without scattering was obtained even after continuous printing of 5000 sheets. After the toner on the sleeve was removed with air, visual observation revealed that no developer was fixed on the sleeve. Table 3 shows the evaluation results of the image density, fog amount and dot reproducibility according to the evaluation method described later.
Shown in

Similarly, under a high temperature and high humidity environment (32.5
85% RH) and low temperature and low humidity environment (10 ° C, 15%
RH). Table 2 shows the results.

Example 2 Magnetic toner particles were obtained in the same manner as in Example 1 except that the hydrophobic iron oxide 1 was changed to 100 parts of the hydrophobic iron oxide 2 and the stirring speed during granulation was changed. To 100 parts of the obtained toner particles, 1.7 parts of hydrophobic colloidal silica was externally added in the same manner as in Example 1 to prepare a toner B (weight average particle size: 4.9 μm).

Using the obtained toner B, an image forming test was performed in the same manner as in Example 1.

Example 3 Toner particles were obtained in the same manner as in Example 1 except that the hydrophobic iron oxide 1 was changed to 150 parts of the hydrophobic iron oxide 3. To 100 parts of the obtained toner particles, 0.7 parts of hydrophobic colloidal silica was externally added in the same manner as in Example 1 to prepare a toner C (weight average particle size: 9.7 μm).

Using the obtained toner C, an image forming test was performed in the same manner as in Example 1.

<Example 4> Toner particles were obtained in the same manner as in Example 1 except that the hydrophobic iron oxide 1 was changed to 190 parts of the hydrophobic iron oxide 4. To 100 parts of the obtained toner particles, 2.0 parts of hydrophobic colloidal silica was externally added in the same manner as in Example 1 to prepare a toner D (weight average particle size: 3.5 μm).

Using the obtained toner D, an image forming test was performed in the same manner as in Example 1.

<Examples 5 and 6> The amount of the hydrophobic iron oxide 3 was changed to 40 parts or 200 parts, and an aqueous solution of Na ₃ PO ₄ and C
Toner particles were obtained in the same manner as in Example 3 except that the amount of the aCl ₂ aqueous solution was changed. To 100 parts of each of the obtained toner particles, 1.0 part of hydrophobic colloidal silica and 3.0 parts of toner were externally added in the same manner as in Example 1, and toners E (weight average particle diameter: 10.5 μm), F (weight average) Particle size 1.9μ
m) was prepared.

Using the toners E and F obtained, Example 1
An image output test was performed in the same manner as described above.

[0272] <Comparative Example 1> After warming to 0.1 mol / liter -Na ₃ PO ₄ aqueous solution 451 parts by mass were charged 60 ° C. in deionized water 709 parts by mass, 1.0 mol / liter-CaCl ₂ aqueous solution 67 0.7 parts by mass was gradually added to obtain an aqueous medium containing Ca ₃ (PO ₄ ) ₂ .

On the other hand, 82 parts of styrene 18 parts of n-butyl acrylate 5 parts of polyester resin 100 parts of hydrophobic iron oxide 1 The above formulation was uniformly dispersed and mixed using an attritor (Mitsui Miike Kakoki Co., Ltd.). did.

The monomer composition was heated to 60 ° C., and the polymerization initiator 2,2′-azobis (2,4-dimethylvaleronitrile [t _1/2 = 140 minutes, under 60 ° C.] 8 Parts by mass and dimethyl-2,2'-azobisisobutyrate [t
_1/2 = 270 minutes at 60 ° C; t _1/2 = 80 minutes at 80 ° C]
2 parts by weight were dissolved.

The above-mentioned polymerizable monomer system was charged into the above-mentioned aqueous medium, and a TK-type homomixer (Special Kika Kogyo Co., Ltd.) was used at 60 ° C. and 10,000 rpm at 10,000 rpm under an N ₂ atmosphere.
The mixture was stirred for 5 minutes and granulated. Thereafter, the mixture was reacted at 60 ° C. for 1 hour while stirring with a paddle stirring blade. After that, the liquid temperature was 80 ° C.
The stirring was continued for another 10 hours. After the completion of the reaction, the suspension was cooled, hydrochloric acid was added to dissolve Ca ₃ (PO ₄ ) ₂ , filtered, washed with water and dried to obtain an iron oxide-containing resin powder having a weight average particle diameter of 10.0 μm.

Next, 205 parts of the above-mentioned iron oxide-containing resin powder, 0.8 parts of a negative charge control agent (monoazo dye-based Fe compound), and 3 parts of an ethylene-propylene copolymer (Mw = 6000) were mixed. The mixture was melted and kneaded with a twin-screw extruder heated to 140 ° C., and after cooling the kneaded material, coarsely pulverized by a hammer mill, the coarsely pulverized material was finely pulverized by a jet mill, and the obtained finely pulverized product was subjected to air classification. Toner particles a were obtained. A mixture obtained by adding 1.2 parts of the hydrophobic colloidal silica used in Example 1 to 100 parts of the toner particles a was mixed with a Henschel mixer to prepare a toner G (weight average particle diameter: 7.4 μm).

Using the obtained toner G, an image forming test was performed in the same manner as in Example 1.

<Comparative Example 2> The toner particles a obtained in Comparative Example 1 were subjected to a surface treatment by mechanical impact to obtain toner particles b. A mixture obtained by adding 1.2 parts of the hydrophobic colloidal silica used in Example 1 to 100 parts of the toner particles b was mixed with a Henschel mixer to prepare a toner H.

Using the obtained toner H, an image forming test was performed in the same manner as in Example 1.

Comparative Example 3 Toner particles were obtained in the same manner as in Example 1, except that the hydrophobic iron oxide 1 was changed to 100 parts of the hydrophobic iron oxide 5. To 100 parts of the obtained toner particles, 1.2 parts of hydrophobic colloidal silica was externally added in the same manner as in Example 1 to prepare a toner I (weight average particle size: 6.9 μm).

The toner I was evaluated for the dispersion state of iron oxide inside the particles by TEM observation in the same manner as in the case of the toner A. As a result, b / a was about 1/6, and the b / a was about 1/6. It was found that the dispersion state was uneven and that a large amount was present especially on the surface of the toner particles. This is probably because iron oxide having non-uniform hydrophobicity caused a large amount of iron oxide powder having low hydrophobicity to collect on the surface of toner particles during suspension polymerization.

Using the obtained toner I, an image forming test was performed in the same manner as in Example 1.

<Comparative Example 4> Toner particles were obtained in the same manner as in Example 1, except that the hydrophobic iron oxide 1 was changed to 150 parts of the hydrophobic iron oxide 6. To 100 parts of the obtained toner particles, 1.7 parts of hydrophobic colloidal silica was externally added in the same manner as in Example 1 to prepare a toner J (weight average particle size: 4.8 μm).

Using the obtained toner J, an image forming test was performed in the same manner as in Example 1.

Table 2 shows the physical properties of each of the obtained toners.
Table 3 shows the image forming test results of the respective toners. The evaluation method is as follows.

A) Image density was measured using a Macbeth densitometer RD
918 (manufactured by Macbeth).

B) The measurement of fog was performed using a RE manufactured by Tokyo Denshoku Co., Ltd.
Measured using FLECTMETER MODELTC-6DS. The filter was calculated using the following formula using a green filter.

Fog (reflectance) (%) = reflectance on standard paper (%) − reflectivity of sample non-image portion (%)

If fog is 2.0% or less, a good image is obtained.

C) The dot reproducibility was 80 μm shown in FIG.
An image-drawing test was performed using a checker pattern of × 50 μm, and the presence or absence of a defect in a black portion was observed and evaluated using a microscope. A: 2 or less defects in 100 B: 3 to 5 defects in 100 C: 6 to 10 defects in 100 D: 11 or more defects in 100

D) The transfer efficiency in the initial stage of the endurance (at the time of 100 sheets) is as follows: The transfer residual toner on the photoreceptor after the transfer of the solid black image is taped off with a Mylar tape, peeled off, and the value of Macbeth density of the tape pasted on paper is expressed as C When the Macbeth density of the Mylar tape pasted on the paper on which the toner was transferred and before fixing was fixed and the Macbeth density of the Mylar tape pasted on the unused paper was D, it was approximately calculated by the following equation. .

[0292]

[Outside 4]

If the transfer efficiency is 90% or more, there is no problem in the image.

[0294]

[Table 2]

[0295]

[Table 3]

(Production Example 1 of Toner) Ion-exchanged water 709
0.1 mol / liter-Na ₃ PO ₄ aqueous solution 4
After charging 51 parts by mass and heating to 60 ° C., 1.0 mol
An aqueous medium containing Ca ₃ (PO ₄ ) ₂ was obtained by gradually adding 67.7 parts by mass of a 1 / liter-CaCl ₂ aqueous solution.

On the other hand, 82 parts of styrene 18 parts of n-butyl acrylate 5 parts of polyester resin 2 parts of negative charge control agent (monoazo dye-based Fe compound) 2 parts 100 parts of hydrophobic iron oxide 1 (Mitsui Miike Kakoki Co., Ltd.) to uniformly disperse and mix.

The monomer composition was heated to 60 ° C., and 20 parts of an ester wax (mp. 70 ° C.) was mixed and dissolved therein, and the polymerization initiator 2,2′-azobis (2,4- 8 parts by mass of dimethylvaleronitrile [t _1/2 = 140 minutes, at 60 ° C.] and dimethyl-2,2′-azobisisobutyrate [t _1/2 = 270 minutes, 60 ° C .; t _{1 / 2} = 8
0 minutes, at 80 ° C.].

The above-mentioned polymerizable monomer system was charged into the above-mentioned aqueous medium, and a TK homomixer (Tokusai Kika Kogyo Co., Ltd.) was used at 60 ° C. and 10,000 rpm under N ₂ atmosphere at 10,000 rpm.
The mixture was stirred for 5 minutes and granulated. Thereafter, the mixture was reacted at 60 ° C. for 1 hour while stirring with a paddle stirring blade. After that, the liquid temperature was 80 ° C.
The stirring was continued for another 10 hours. After the completion of the reaction, the suspension was cooled, and hydrochloric acid was added to dissolve Ca ₃ (PO ₄ ) ₂ , followed by filtration, washing with water and drying to obtain toner particles.

The toner particles (100 parts) were treated with hexamethyldisilazane, treated with silicone oil, and treated with 1.4 parts of hydrophobic silica fine powder having a BET value of 120 m ² / g. A Henschel mixer (Mitsui Miike) The toner K (weight average particle diameter: 6.1 μm) was mixed by Kakokiki Co., Ltd.
m) was prepared.

(Production Example 2 of Toner) Magnetic toner particles were obtained in the same manner as in Production Example 1 except that the hydrophobic iron oxide 1 was changed to 100 parts of the hydrophobic iron oxide 2. The obtained toner particles 10
To 0 part, 1.7 parts of hydrophobic colloidal silica was externally added in the same manner as in Production Example 1, and toner L (weight average particle size: 5.0 μm)
Was prepared.

(Production Example 3 of Toner) Toner particles were obtained in the same manner as in Production Example 1, except that hydrophobic iron oxide 1 was changed to 150 parts of hydrophobic iron oxide 3. In 100 parts of the obtained toner particles, hydrophobic colloidal silica 0.7 was prepared in the same manner as in Production Example 1.
The toner M (weight average particle size: 9.8 μm) was prepared by externally adding the above components.

(Toner Production Example 4) Toner particles were obtained in the same manner as in Production Example 1, except that the hydrophobic iron oxide 1 was changed to 190 parts of the hydrophobic iron oxide 4. The hydrophobic colloidal silica 2.0 was added to 100 parts of the obtained toner particles in the same manner as in Production Example 1.
The toner N (weight average particle size: 3.6 μm) was prepared by externally adding the above components.

(Toner Production Examples 5 and 6) Hydrophobic iron oxide 3
Was changed to 10 parts or 200 parts, and the toner particles were obtained in the same manner as in Production Example 3 except that the amounts of the aqueous Na ₃ PO ₄ solution and the aqueous CaCl ₂ solution were changed. To 100 parts of each of the obtained toner particles, 1.0 part of hydrophobic colloidal silica and 3.0 parts of hydrophobic colloidal silica were externally added in the same manner as in Production Example 1 to prepare toners O (weight average particle diameter of 10.9 μm) and P (weight average). (Particle size 2.4 μm) was prepared.

(Comparative Production Example 1 of Toner) Ion-exchanged water 7
After adding 451 parts by mass of a 0.1 mol / l-Na ₃ PO ₄ aqueous solution to 09 parts by mass and heating to 60 ° C., 1.0 m
Then, 67.7 parts by mass of an ol / liter-CaCl ₂ aqueous solution was gradually added to obtain an aqueous medium containing Ca ₃ (PO ₄ ) ₂ .

On the other hand, 82 parts of styrene 18 parts of n-butyl acrylate 5 parts of polyester resin 100 parts of hydrophobic iron oxide 1 The above formulation was uniformly dispersed and mixed using an attritor (Mitsui Miike Kakoki Co., Ltd.). did.

The monomer composition was heated to 60 ° C., and added with a polymerization initiator 2,2′-azobis (2,4-dimethylvaleronitrile [t _1/2 = 140 minutes, at 60 ° C.] 8 Parts by mass and dimethyl-2,2'-azobisisobutyrate [t
_1/2 = 270 minutes at 60 ° C; t _1/2 = 80 minutes at 80 ° C]
2 parts by weight were dissolved.

The above-mentioned polymerizable monomer system was charged into the above-mentioned aqueous medium, and a TK homomixer (Tokusai Kika Kogyo Co., Ltd.) was used at 10,000 rpm at 60 ° C. in an N ₂ atmosphere.
The mixture was stirred for 5 minutes and granulated. Thereafter, the mixture was reacted at 60 ° C. for 1 hour while stirring with a paddle stirring blade. After that, the liquid temperature was 80 ° C.
The stirring was continued for another 10 hours. After the completion of the reaction, the suspension was cooled, hydrochloric acid was added to dissolve Ca ₃ (PO ₄ ) ₂ , filtered, washed with water and dried to obtain an iron oxide-containing resin powder having a weight average particle diameter of 10.0 μm.

Next, 205 parts of the above-described iron oxide-containing resin powder, 0.8 parts of a negative charge control agent (monoazo dye-based Fe compound), and 3 parts of an ethylene-propylene copolymer (Mw = 6000) were mixed. The mixture was melted and kneaded with a twin-screw extruder heated to 140 ° C., and after cooling the kneaded material, coarsely pulverized by a hammer mill, the coarsely pulverized material was finely pulverized by a jet mill, and the obtained finely pulverized product was subjected to air classification. Thus, toner particles c were obtained. A mixture of 100 parts of the toner particles c and 1.2 parts of the hydrophobic colloidal silica used in Production Example 1 was mixed with a Henschel mixer to prepare a toner Q (weight average particle diameter 7.2 μm).

(Comparative Production Example 2 of Toner) The toner particles c obtained in Comparative Production Example 1 were subjected to surface treatment by mechanical impact to obtain toner particles d. The hydrophobic colloidal silica 1.2 used in Production Example 1 was used for 100 parts of the toner particles d.
The resulting mixture was mixed with a Henschel mixer to prepare toner R.

(Comparative Production Example 3 of Toner) Toner particles were obtained in the same manner as in Production Example 1, except that hydrophobic iron oxide 1 was changed to 100 parts of hydrophobic iron oxide 5. The obtained toner particles 10
To 0 part, 1.2 parts of hydrophobic colloidal silica was externally added in the same manner as in Production Example 1, and toner S (weight average particle size: 7.0 μm)
Was prepared.

(Comparative Production Example 4 of Toner) Toner particles were obtained in the same manner as in Production Example 1, except that hydrophobic iron oxide 1 was changed to 150 parts of hydrophobic iron oxide 6. The obtained toner particles 10
To 0 parts, 1.7 parts of hydrophobic colloidal silica was externally added in the same manner as in Production Example 1, and toner T (weight average particle size: 4.6 μm)
Was prepared.

Table 4 shows the physical properties of the obtained toners.

[0314]

[Table 4]

[Examples 7 to 12 and Comparative Examples 5 to 8] FIG.
And 60 as an electrophotographic apparatus having a configuration such as
0 dpi laser beam printer (Canon: LB
P-860). Process speed is 60m
m / s.

The cleaning blade of the process cartridge was removed, the charging method of the apparatus was set to direct charging performed by contacting a rubber roller, and the applied voltage was set to only the DC component (−1200 V).

Next, the developing portion of the process cartridge was modified. A medium-resistance rubber roller (diameter 16 mm, hardness A) made of silicone rubber in which carbon black is dispersed instead of the stainless steel sleeve as the toner carrier
SKER C45 degree, resistance 10 ⁵ Ω · cm)
The photosensitive member was brought into contact with the photosensitive member. The developing contact width at this time was set to about 3 mm. The rotation speed of the toner carrier is the same in the contact portion with the photoconductor, and the toner carrier is driven to be 140% of the rotation speed of the photoconductor.

The photosensitive member used here has a diameter of 30 m.
A photoreceptor was manufactured by sequentially laminating layers having the following configurations by dip coating on an Al cylinder having a length of 254 mm and a length of 254 mm. (1) Conductive coating layer: Mainly composed of tin oxide and titanium oxide powder dispersed in a phenol resin. 15μ thickness
m. (2) Undercoat layer: mainly composed of modified nylon and copolymerized nylon. The film thickness is 0.6 μm. (3) Charge generation layer: mainly composed of a butyral resin in which a titanyl phthalocyanine pigment having absorption in a long wavelength region is dispersed. The film thickness is 0.6 μm. (4) Charge transporting layer: mainly composed of a hole transporting triphenylamine compound dissolved in a polycarbonate resin (molecular weight 20,000 according to Ostwald viscosity method) at a mass ratio of 8:10. Film thickness 20 μm.

As means for applying toner to the toner carrier, an application roller made of urethane foam rubber was provided in the developing device, and was brought into contact with the toner carrier. For the application roller,
A voltage of about -550 V is applied. Further, a stainless steel blade coated with a resin for controlling the coat layer of the toner on the toner carrier was attached so that the contact pressure with the toner carrier was about 20 g / cm. An outline is shown in FIG. Further, the applied voltage at the time of development is changed to a DC component (-450 V).
Only.

The electrophotographic apparatus was modified and the process conditions were set as follows so as to be adapted to the modification of these process cartridges.

The modified device uniformly charges the photoreceptor using a roller charger (only DC is applied). After charging, an image is exposed to a laser beam to form an electrostatic latent image by exposing the image to a visible image by developing with a toner, and then a toner image is transferred to a transfer material by a roller to which a voltage of +700 V is applied. Have.

Further, the charging potential of the photoreceptor is set to -5
80 V, and the bright portion potential was -150 V. 75 g / m ² paper was used as the transfer material.

Using the toners K to T, an image forming test was performed by the above-described image forming apparatus under a normal temperature and normal humidity environment (23 ° C., 65% RH). The durability was evaluated as follows.

A) The contamination of the charging member of the developer was judged by the number of durable sheets on which the charging unevenness occurred due to the charging member contamination on the halftone image and the solid white image where the image defect due to the charging defect was apt to appear. The greater the number of generated sheets, the better the durability of the developer.

B) The method of measuring the transfer efficiency in the early stage of durability is the same as that shown in Table 3 above.

C) The recoverability of the toner in the developing step was determined based on whether or not an image (a so-called ghost image) in a non-printed portion occurred on the obtained image sample. That is, if the toner remaining on the photoreceptor without being transferred is recovered in the developing process, no image is generated in the non-printed portion. However, if the recoverability of the toner is not good, the uncollected toner is subjected to the transferring process again. Ghost image is generated.

A: No ghost is generated B: Good (a level that cannot be confirmed without staring at the image) C: Ghost is generated, but is at a practical level

If no ghost or uneven charging occurs, 5
Printout was continued up to 000 sheets (5K).

D) The resolving power in the early stage of durability (at the time of 100 sheets) is
The electric field is easily closed by the latent image electric field, making it difficult to reproduce 60
The evaluation was made based on the reproducibility of a small-diameter isolated dot (diameter: 60 μm) at 0 dpi.

A: 5 or less defects in 100 B: 6 to 10 defects in 100 C: 11 to 20 defects in 100 D: 21 or more defects in 100

E) The measurement of fog is the same as that shown in Table 3 above.

Similarly, in a high temperature and high humidity environment (32.5
85% RH) and low temperature and low humidity environment (10 ° C, 15%
RH). Table 5 shows the results.

[0333]

[Table 5]

(Production Example 7 of Hydrophobic Iron Oxide) In a ferrous sulfate aqueous solution, an amount of l. An aqueous solution containing ferrous hydroxide was prepared by mixing 0 to 1.1 equivalents of a sodium hydroxide solution.

While maintaining the pH of the aqueous solution at about 9, air was blown therein to carry out an oxidation reaction at 80 to 90 ° C. to prepare a slurry liquid for generating seed crystals.

Next, the slurry was added in an amount of 0.9 to 1.0 based on the initial alkali amount (sodium component of caustic soda).
After adding an aqueous solution of ferrous sulfate so as to be 2 equivalents, the slurry liquid is maintained at pH 8, and the oxidation reaction is promoted while blowing air thereinto. The magnetic iron oxide particles generated after the oxidation reaction are washed, filtered, and once filtered. I took it out. At this time, a small amount of a water-containing sample was collected, and the water content was measured. Next, after re-dispersing this water-containing sample in another aqueous medium without drying, the pH of the re-dispersed liquid was adjusted to about 6, and the silane coupling agent (n-C ₁₀ H ₂₁₎ was mixed with sufficient stirring. Si (OCH ₃ ) ₃ ) was added to 0.5 part of magnetic iron oxide to 100 parts of magnetic iron oxide (the amount of magnetic iron oxide was calculated as a value obtained by subtracting the water content from a water-containing sample) to perform a coupling treatment. The resulting hydrophobic iron oxide particles were washed, filtered, and dried by a conventional method, and then the particles slightly aggregated were crushed to obtain hydrophobic iron oxide 7.

(Production Example 1 of Magnetic Material) The oxidation reaction was advanced in the same manner as in Production Example 7 of magnetic iron oxide, and the magnetic iron oxide particles formed after the oxidation reaction were washed, filtered, and dried to dissolve aggregated particles. Crushing treatment was performed to obtain a magnetic body 1.

(Production Example 8 of Hydrophobic Iron Oxide) The magnetic substance 1 obtained in Production Example 1 of the magnetic substance was redispersed in another aqueous medium, and the pH of the redispersed liquid was adjusted to about 6. Silane coupling agent (n-C ₁₀ H ₂₁ Si (OCH
₃ ) ₃ ) was added to magnetic iron oxide in an amount of 0.5 part to perform a coupling treatment. The produced hydrophobic iron oxide particles were washed, filtered, and dried by a conventional method, and then the aggregated particles were crushed to obtain hydrophobic iron oxide 8.

(Production Example 9 of Hydrophobic Iron Oxide) In Production Example 7 of hydrophobic iron oxide, the aqueous ferrous sulfate solution during the synthesis of magnetic iron oxide particles was reduced, and the air blowing amount was increased.
Thus, hydrophobic iron oxide 9 was obtained.

(Production Example 10 of Hydrophobic Iron Oxide) The same procedure as in Production Example 7 of hydrophobic iron oxide was carried out except that the aqueous ferrous sulfate solution was increased during the synthesis of the magnetic iron oxide particles and the amount of air blown was reduced. Thus, hydrophobic iron oxide 10 was obtained.

(Production Example 11 of Hydrophobic Iron Oxide) In Production Example 1 of hydrophobic iron oxide 7, the amount of air blown during the synthesis of magnetic iron oxide particles was increased to obtain hydrophobic iron oxide 11.

The hydrophobic iron oxide 7-
Table 6 shows the physical properties of 11 and the magnetic body 1.

[0343]

[Table 6]

<Production Example 7 of Toner> Ion-exchanged water 709
0.1 mol / liter-Na ₃ PO ₄ aqueous solution 4
After charging 51 parts by mass and heating to 60 ° C., 1.0 mol
An aqueous medium containing Ca ₃ (PO ₄ ) ₂ was obtained by gradually adding 67.7 parts by mass of a 1 / liter-CaCl ₂ aqueous solution.

80 parts of styrene 20 parts of n-butyl acrylate 20 parts of an unsaturated polyester resin obtained by the condensation reaction of bisphenol A with propylene oxide adduct and ethylene oxide adduct with fumaric acid 2 parts Negative charge control agent (shown in the following formula) Monoazo dye-based Fe compound) 4 parts Hydrophobic iron oxide 180 parts The above formulation was uniformly dispersed and mixed using an attritor (Mitsui Miike Kakoki Co., Ltd.).

[0346]

[Outside 5]

The monomer composition was heated to 60 ° C., and 10 parts of an ester wax having an endothermic peak temperature of 75 ° C. in DSC was added thereto and mixed, and the polymerization initiator 2, 2 ′ was added thereto.
-Azobis (2,4-dimethylvaleronitrile) [t
_1/2 = 140 minutes, at 60 ° C.] 8 parts by mass and dimethyl-2,2′-azobisisobutyrate [t _1/2 = 270
Min, at 60 ° C .; t _1/2 = 80 min, at 80 ° C.] 2
Parts by weight were dissolved.

The above-mentioned polymerizable monomer system was charged into the above-mentioned aqueous medium, and a TK-type homomixer (Tokusai Kika Kogyo Co., Ltd.) was used at 60 ° C. and 10,000 rpm under N ₂ atmosphere.
The mixture was stirred for 5 minutes and granulated. Thereafter, the mixture was reacted at 60 ° C. for 1 hour while stirring with a paddle stirring blade. After that, the liquid temperature was 80 ° C.
The stirring was continued for another 10 hours. After completion of the reaction, the suspension was cooled, hydrochloric acid was added to dissolve Ca ₃ (PO ₄ ) ₂ , filtered, washed with water and dried to obtain magnetic toner particles having a weight average particle diameter of 7.0 μm.

100 parts of the magnetic toner particles and 1.2 parts of a hydrophobic silica fine powder having a BET specific surface area of 200 m ² / g after treating the surface with hexamethyldisilazane were mixed with a Henschel mixer (Mitsui Miike Koki Co., Ltd.). To prepare toner U. Table 7 shows the physical properties of Toner U.

The toner U was evaluated for the state of dispersion of iron oxide inside the particles by TEM observation in the same manner as in the case of the toner A. As a result, b / a was almost 1/4, and Was found to be very uniform.

<Production Example 8 of Toner> Magnetic toner particles having a weight average particle size of 6.9 μm were obtained in the same manner as in Production Example 7 of the toner.

The magnetic toner particles (100 parts) were treated with hexamethyldisilazane, and then treated with silicone oil.
Toner V was prepared by mixing 1.2 parts of the hydrophobic silica fine powder having a BET specific surface area of 180 m ² / g after the treatment with a Henschel mixer (Mitsui Miike Kakoki Co., Ltd.). Table 7 shows the physical properties of Toner V.

<Production Example 9 of Toner> In Production Example 7 of toner, the amounts of the aqueous Na ₃ PO ₄ solution and CaCl ₂ solution were changed, and the weight average particle diameter was 3.8 μm using sodium dodecylbenzenesulfonate. Was obtained. Toner W was prepared by mixing 100 parts of the magnetic toner particles and 2.5 parts of the hydrophobic silica fine powder used in Toner Production Example 8 with a Henschel mixer (Mitsui Miike Kakoki Co., Ltd.). Table 7 shows the physical properties of Toner W.

<Production Example 10 of Toner> Production Example 7 of Toner
, The amounts of the aqueous Na ₃ PO ₄ solution and the aqueous CaCl ₂ solution were changed to obtain magnetic toner particles having a weight average particle diameter of 10.4 μm. 100 parts of the magnetic toner particles and 0.8 part of the hydrophobic silica fine powder used in Toner Production Example 8 were mixed with a Henschel mixer (Mitsui Miike Kakoki Co., Ltd.),
Toner X was prepared. Table 7 shows the physical properties of Toner X.

<Production Example 11 of Toner> Production Example 7 of Toner
, Magnetic toner particles having a weight average particle size of 8.2 μm were obtained in the same manner except that the amount of the ester wax used was changed to 51 parts. A toner Y was prepared by mixing 100 parts of the magnetic toner particles and 1.1 parts of the hydrophobic silica fine powder used in Production Example 8 of the toner with a Henschel mixer (Mitsui Miike Kakoki Co., Ltd.). Table 7 shows the physical properties of Toner Y.

<Toner Production Example 12> Toner Production Example 7
, Magnetic toner particles having a weight average particle size of 6.8 μm were obtained in the same manner except that the amount of the ester wax used was changed to 0.4 part. 100 parts of the magnetic toner particles,
Hydrophobic silica fine powder used in Toner Production Example 8 1.2
Were mixed with a Henschel mixer (Mitsui Miike Kakoki Co., Ltd.) to prepare toner Z. Table 7 shows the physical properties of Toner Z.
Shown in

<Production Example 13 of Toner> Production Example 7 of Toner
In this example, magnetic toner particles having a weight average particle diameter of 8.4 μm were obtained in the same manner except that 10 parts of a low molecular weight polyethylene wax having an endothermic peak temperature in DSC of 115 ° C. was used instead of the ester wax. 100 parts of the magnetic toner particles and 1.1 parts of the hydrophobic silica fine powder used in Toner Production Example 8 were mixed with a Henschel mixer (Mitsui Miike Kakoki Co., Ltd.) to prepare toner AA. Table 7 shows the physical properties of Toner AA.

<Production Example 14 of Toner> Production Example 7 of Toner
, Magnetic toner particles having a weight average particle size of 6.9 μm were obtained in the same manner except that the amount of the hydrophobic iron oxide 7 was changed to 30 parts. Toner BB was prepared by mixing 100 parts of the magnetic toner particles and 1.2 parts of the hydrophobic silica fine powder used in Production Example 8 of the toner with a Henschel mixer (Mitsui Miike Kakoki Co., Ltd.). Table 7 shows the physical properties of Toner BB.
Shown in

<Production Example 15 of Toner> Production Example 7 of Toner
, Magnetic toner particles having a weight average particle size of 7.9 μm were obtained in the same manner except that 205 parts of hydrophobic iron oxide 7 was used. 100 parts of the magnetic toner particles and 1.1 parts of the hydrophobic silica fine powder used in Toner Production Example 8 were mixed with a Henschel mixer (Mitsui Miike Kakoki Co., Ltd.) to prepare a toner CC. Table 7 shows the physical properties of Toner CC.

<Toner Production Examples 16 to 18> Magnetic toners were obtained in the same manner as in Toner Production Example 7, except that hydrophobic iron oxides 9 to 11 were used instead of hydrophobic iron oxide 7. 100 parts of these magnetic toner particles and 1.2 parts of the hydrophobic silica fine powder used in Toner Production Example 8 were mixed with a Henschel mixer (Mitsui Miike Kakoki Co., Ltd.) to prepare toners DD to FF. Prepared. Table 7 shows the physical properties of Toners DD to FF.

<Comparative Production Example 5 of Toner> A weight-average particle diameter of 8.8 was obtained in the same manner as in Production Example 7 of the toner except that 80 parts of the magnetic material 1 was used instead of the hydrophobic iron oxide 7.
μm of magnetic toner particles were obtained. The magnetic toner particles 10
Toner GG prepared by mixing 0 parts with 1.0 part of the hydrophobic silica fine powder used in Production Example 8 of the toner with a Henschel mixer (Mitsui Miike Kakoki Co., Ltd.).
Table 7 shows the physical properties of the product.

When the dispersion state of iron oxide inside the particles was evaluated by TEM observation of this toner GG in the same manner as in the case of toner A, b / a was about ８, and the iron oxide Was found to be non-uniform, and it was found that the dispersion was extremely large especially on the surface of the toner particles.

<Comparative Production Example 6 of Toner> A weight-average particle size of 8.1 μm was obtained in the same manner as in Production Example 7 of the toner except that 80 parts of hydrophobic iron oxide 8 was used in place of the hydrophobic iron oxide 7. Was obtained. 100 parts of the magnetic toner particles and 1.1 parts of the hydrophobic silica fine powder used in Production Example 8 of the toner were mixed with a Henschel mixer (Mitsui Miike Kakoki Co., Ltd.) to prepare a toner HH. Table 7 shows the physical properties of Toner HH.

When the dispersion state of iron oxide in the toner HH was evaluated by TEM observation in the same manner as in the case of the toner A, b / a was about 1/6 and the iron oxide in the toner particles was about Was found to be non-uniform, and it was found that the dispersion was extremely large especially on the surface of the toner particles.

<Comparative Production Example 7 of Toner> Styrene / n-butyl acrylate copolymer (80/20 by weight) 20 parts Obtained by the condensation reaction of propylene oxide adduct of bisphenol A and ethylene oxide adduct with fumaric acid. Unsaturated polyester resin 2 parts Negative charge control agent (monoazo dye-based Fe compound used in toner production example 7) 4 parts Hydrophobic iron oxide 780 parts Ester wax used in toner production example 7 5 parts Are mixed in a blender, melt-kneaded in a twin-screw extruder heated to 110 ° C., the cooled kneaded material is coarsely pulverized in a hammer mill, the coarsely pulverized material is finely pulverized in a jet mill, and the obtained finely pulverized material is obtained. Was subjected to air classification to obtain magnetic toner particles having a weight average particle diameter of 10.4 μm. A mixture of 100 parts of the magnetic toner particles and 0.8 part of the hydrophobic silica fine powder used in Toner Production Example 8 was mixed with a Henschel mixer to prepare Toner II. Table 7 shows the physical properties of Toner II.

<Comparative Production Example 8 of Toner> Magnetic toner particles were obtained in the same manner as in Comparative Production Example 7 of the toner, except that the coarsely pulverized product was finely pulverized with a turbo mill (manufactured by Turbo Industries, Ltd.). Then, an impact type surface treatment device (processing temperature 50
° C, peripheral speed of the rotary processing blade 90 m / sec. ) To obtain a spherical toner having a weight average particle diameter of 10.3 μm.

Next, a mixture obtained by adding 0.8 parts of the hydrophobic silica fine powder used in Toner Production Example 8 to 100 parts of the obtained spherical toner was mixed with a Henschel mixer to prepare toner JJ. Table 7 shows the physical properties of Toner JJ.

<Comparative Production Example 9 of Toner> Ion-exchanged water 7
After adding 451 parts by mass of a 0.1 mol / l-Na ₃ PO ₄ aqueous solution to 09 parts by mass and heating to 60 ° C., 1.0 m
Then, 67.7 parts by mass of an ol / liter-CaCl ₂ aqueous solution was gradually added to obtain an aqueous medium containing Ca ₃ (PO ₄ ) ₂ .

80 parts of styrene 20 parts of n-butyl acrylate 20 parts of an unsaturated polyester resin obtained by a condensation reaction of a propylene oxide adduct of bisphenol A and an ethylene oxide adduct with fumaric acid 2 parts Load control agent (Toner Production Example 7) 4 parts Hydrophobic iron oxide 796 parts The above formulation was uniformly dispersed and mixed using an attritor (Mitsui Miike Kakoki Co., Ltd.).

This monomer composition was heated to 60 ° C., and 12 parts of the ester wax used in Toner Production Example 7 was added thereto and mixed, and the polymerization initiator 2,2′-azobis (2,2) was added thereto. 4-dimethylvaleronitrile) [t _1/2 = 140
Min, at 60 ° C.] 8 parts by mass and dimethyl-2,2′-
2 parts by mass of azobisisobutyrate [t _1/2 = 270 minutes, at 60 ° C .; t _1/2 = 80 minutes, 80 ° C.] were dissolved.

The above-mentioned polymerizable monomer system was charged into the above-mentioned aqueous medium, and a TK homomixer (Tokusai Kika Kogyo Co., Ltd.) was used at 10,000 rpm at 60 ° C. in an N ₂ atmosphere.
The mixture was stirred for 5 minutes and granulated. Thereafter, the mixture was reacted at 60 ° C. for 1 hour while stirring with a paddle stirring blade. After that, the liquid temperature was 80 ° C.
The stirring was continued for another 10 hours.

Next, styrene 16 parts n-butyl acrylate 4 parts 2,2′-azobis (2,4-dimethylvaleronitrile) 0.4 part sodium behenate 0.1 part water 20 in this aqueous suspension Then, the mixture was again heated to 80 ° C. and stirring was continued for 10 hours. After the completion of the reaction, the suspension was cooled, hydrochloric acid was added to dissolve Ca ₃ (PO ₄ ) _2, and the mixture was filtered, washed with water and dried to obtain toner particles having a weight average particle size of 8.5 μm.

Toner KK was prepared by mixing 100 parts of the toner particles and 1.0 part of the hydrophobic silica fine powder used in Production Example 8 of the toner with a Henschel mixer (Mitsui Miike Kakoki Co., Ltd.). . Table 7 shows the physical properties of Toner KK.

<Comparative Production Example 10 of Toner> In Production Example 9 of the toner, the magnetic material 1 was replaced with the hydrophobic iron oxide 7 by 96.
7. A weight average particle size of 8.
3 μm magnetic toner particles were obtained. The magnetic toner particles 1
Toner LL prepared by mixing 00 parts with 1.0 part of the hydrophobic silica fine powder used in Toner Production Example 8 using a Henschel mixer (Mitsui Miike Kakoki Co., Ltd.).
Table 7 shows the physical properties of the product.

[0375]

[Table 7]

(Production Example 1 of Photoconductor) A photoconductor having a diameter of 3
0 was used as a substrate. Then, layers having the structure shown in FIG. 8 were sequentially laminated by dip coating to prepare a photoreceptor. (1) Conductive coating layer: mainly composed of tin oxide and titanium oxide powder dispersed in a phenol resin. 15μ thickness
m. (2) Undercoat layer: mainly composed of modified nylon and copolymerized nylon. The film thickness is 0.6 μm. (3) Charge generation layer: mainly composed of an azo pigment having absorption in a long wavelength region dispersed in butyral resin. Thickness 0.6
μm. (4) charge transporting layer: mainly composed of a hole-transporting triphenylamine compound dissolved in a polycarbonate resin (molecular weight 20,000 according to Ostwald viscosity method) at a mass ratio of 8:10, and a polytetrafluoroethylene powder ( Particle size 0.2
μm) was added at 10% by mass based on the total solid content, and the mixture was uniformly dispersed. The film thickness is 25 μm and the contact angle with water is 9
5 degrees.

The contact angle was measured using pure water and a contact angle meter CA-X manufactured by Kyowa Interface Science Co., Ltd.

(Example 1) As an image forming apparatus, the one generally shown in Fig. 1 was used.

The organic photoconductor (OPC) drum of (Photoconductor Production Example 1) was used as the electrostatic image carrier. A rubber roller charger coated with nylon resin and dispersed with conductive carbon as a primary charging member is brought into contact with the photoreceptor (contact pressure: 60 g / cm), and an AC voltage of 2.0 kVpp is superimposed on a DC voltage of -700 Vdc. The applied bias is applied to uniformly charge the photosensitive member. Following the primary charging, an electrostatic latent image is formed by exposing the image portion with a laser beam. At this time, the dark part potential Vd = −700 V and the light part potential VL
= -200V.

The gap between the photosensitive drum and the developing sleeve is 28
0 μm, and a layer thickness of about 7
using a developing sleeve in which a resin layer having a JIS center line average roughness (Ra) of 1.3 μm is formed on an aluminum cylinder having a mirror surface with a diameter of 20 and a developing magnetic pole of 95 mT
(950 gauss), 1.0 m thick as toner regulating member
m, a urethane rubber blade having a free length of 10 mm.
The contact was performed at a linear pressure of 7 N / m (15 kg / m).

Phenol resin 100 parts Graphite (particle size: about 7 μm) 90 parts Carbon black 10 parts

Next, a DC bias component Vdc = −400 V as a developing bias and a superimposed AC bias component V
_pp = 1600 V and f = 2000 Hz were used. Further, the peripheral speed of the developing sleeve is 110% faster (88 mm / sec) with respect to the peripheral speed of the photoconductor (80 mm / sec).
c).

Also, as shown in FIG. 5, a transfer roller (made of ethylene-propylene rubber in which conductive carbon is dispersed, the volume resistance value of the conductive elastic layer is 10 ⁸ Ωcm, and the surface rubber hardness is 24
゜, diameter 20 mm, contact pressure 59 N / m (6 kg /
m)) is changed to the peripheral speed of the photoconductor in the direction A in FIG. 5 (80 mm / sec).
c) at a constant speed, and the transfer bias is DC 1.5 kV
And

As a fixing method, a heat roller fixing device was used.

First, using toner U as toner,
An image-drawing test was performed in a 5 ° C., 10% RH environment. 90 g / m ² paper was used as the transfer material. as a result,
A good image was obtained in the early stage, showing high transferability, no missing characters or lines during transfer, no back stain due to fixing offset, and no fog on non-image areas.

Next, durability was evaluated with an image pattern consisting of only vertical lines having a print area ratio of 5%.

Image evaluation was performed as follows.

Evaluation of scraping of the photoreceptor and fusing of the toner was made on the basis of the number of durable sheets on which a defective image due to abrasion or fusing of the toner, that is, black spots or white spots occurred, on a halftone image in which image defects were apt to appear. The larger the number of durable sheets before occurrence, the better the durability of the image forming method. In addition, image defects due to primary charging failure due to transfer residual toner, that is, charging unevenness were also evaluated on the halftone image. When these image defects did not occur, the durability test was continued up to 5000 printed sheets. a) The method of measuring the transfer efficiency is the same as that shown in Table 3 above. b) The method of evaluating the resolving power in the early stage of durability is the same as that shown in Table 5 above. c) The method of measuring the image density is the same as that shown in Table 3 above. d) Evaluation of fog is the same as the case shown in Table 3 above. e) The fixing offset property was determined by observing the stains generated on the back side of the image sample from the initial stage to the endurance of 100 sheets, and counting the number of sheets generated.

Table 8 shows the obtained results.

(Example 14) An image forming test was performed by using the toner V as the toner and by the same image forming method as in Example 13. As shown in Table 8, up to 5000 prints were obtained. Good results were obtained.

(Examples 15 to 24) Using the toners W to FF as the toner, an image forming test was performed by the same image forming method as in Example 13. As a result, as shown in Table 8, a practically satisfactory result was obtained.

(Comparative Example 9) An image forming test was performed by using the toner GG as the toner and by the same image forming method as in Example 13. As a result, black spots due to scraping of the photoreceptor are generated on the halftone image from the 2500th printing sheet, and 3
From the 000th sheet, white spots due to toner fusion began to occur. It is considered that iron oxide was largely exposed from the surface of the toner due to the use of the untreated magnetic material, and the transfer residual toner scraped the photoconductor during the rubbing by the charging roller.

(Comparative Example 10) An image forming test was performed in the same manner as in Example 13, except that the toner HH was used as the toner. As a result, black spots are generated on the halftone image from the 3500th printed sheet due to shaving of the photoconductor,
From the 4000th sheet, white spots due to toner fusion began to occur. Since the hydrophobic treatment of the used hydrophobic iron oxide is not uniform, the exposure of the iron oxide from the toner surface cannot be completely prevented.
This is probably because the transfer residual toner has scraped the photoreceptor during the rubbing by the charging roller.

(Comparative Example 11) An image forming test was performed by using the toner II as the toner and by the same image forming method as in Example 13. As a result, black spots are generated on the halftone image from the 1000th printed sheet due to shaving of the photoconductor,
From the 1500th sheet, white spots occurred due to fusion of toner, and from the 2,000th sheet, uneven charging due to transfer residual toner also started to occur. Even when iron oxide whose surface is uniformly hydrophobicized is used, if the toner is manufactured by a general pulverization method, the exposure of the iron oxide from the toner surface cannot be completely prevented, and the transfer residual toner is rubbed by the charging roller. This is probably because the photoreceptor has been scraped. Further, since the circularity is low, the toner particles are also scraped off by the edge portions, and the deterioration of the photoreceptor is considered to be accelerated.

(Comparative Example 12) An image forming test was performed by using the same image forming method as in Example 13 except that the toner JJ was used as the toner. As a result, black spots are generated on the halftone image from the 2500th printed sheet due to shaving of the photoconductor,
From the 3000th sheet, white spots occurred due to fusion of the toner, and from the 3500th sheet, uneven charging due to the transfer residual toner also started to occur. During the sphering treatment of the toner surface, the exposure of iron oxide from the toner surface was improved, but the degree of circularity was not yet sufficient, and the improvement of the abrasion of the photoconductor by the edge of the toner particles was insufficient. Conceivable.

(Comparative Example 13) An image forming test was performed in the same manner as in Example 13, except that the toner KK was used as the toner. As a result, as shown in Table 8, a result having no problem was obtained with respect to an image defect caused by scraping of the photoreceptor. However, as the number of prints increased, the image density decreased, and after 5,000 prints, the image density decreased to 0.71. Furthermore, back stains began to occur after 4000 sheets of durability. This is because the number of particles with D / C ≦ 0.02 is 4
It is considered that the reason is that only the toner having a large particle size, containing a large amount of iron oxide, and having low developability and low fixability was left because of a low 4%, that is, poor dispersibility of iron oxide in the developer. It is.

(Comparative Example 14) An image forming test was performed in the same manner as in Example 13, except that the toner LL was used as the toner. As a result, a result having no particular problem was obtained with respect to an image defect caused by scraping of the photoconductor. However, as the number of prints increased, the image density decreased, and after 5,000 prints, the image density decreased to 0.67. Also, back stains began to occur after 3,500 sheets of durability. This is presumably because, similarly to the case of Comparative Example 13 using the toner KK, only the toner having low developability and low fixability remained. Further, from the 4000th sheet of durability, charging unevenness due to transfer residual toner occurred. This is presumably because the amount of toner remaining after transfer was large due to insufficient circularity of the toner. Both phenomena are considered to be due to the fact that the toner was manufactured using iron oxide whose surface was not subjected to a hydrophobic treatment.

[0398]

[Table 8]

[0399]

According to the present invention, in an image forming method using a one-component developer, the iron element content on the surface /
When the ratio of the carbon element content is less than 0.001, the diameter equivalent to the projected area of the toner is C, and the minimum value of the distance between the iron oxide and the toner surface is D, the relationship of D / C ≦ 0.02 By using a developer having 50% by number or more of toner satisfying the following condition and having an average circularity of 0.970 or more,
No scraping of the photoconductor or fusion of the toner occurs, and a high-quality image with excellent resolution can be stably obtained for a long time even under low humidity.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of an image forming apparatus using a non-contact developing method.

FIG. 2 is an enlarged view of a developing unit of the image forming apparatus shown in FIG.

FIG. 3 is a diagram illustrating an example of an image forming apparatus using a contact developing method.

FIG. 4 is an enlarged view of a developing unit of the image forming apparatus shown in FIG.

FIG. 5 is a diagram illustrating an example of a contact transfer member.

FIG. 6 is a diagram illustrating a pattern of a developing bias of the image forming apparatus.

FIG. 7 is an explanatory diagram of a checker pattern for testing development characteristics of a toner.

FIG. 8 is a diagram illustrating an example of a configuration of a photoconductor.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 15/08 501 G03G 15/08 506A 504 9/08 301 506 302 507 381 384 15/08 507L 507B (72 ) Inventor Motoki Hisagi 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Keiji Kawamoto 3-30-2 Shimomaruko 3-chome, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Michihisa Magome 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Tatehiko Chiba 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Akira Hashimoto Tokyo 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 2H005 AA02 AA03 AA06 AA08 AA15 AB02 AB06 CA14 CA26 CB03 EA05 EA07 EA10 FA06 2H073 AA03 BA03 BA13 BA43 CA02 2H077 AA37 AC16 AD02 AD06 AD11 AD17 AD23 AD35 BA03 BA07 EA13 FA01 FA21

Claims (36)

[Claims] Claims 1. A toner having toner particles containing at least a binder resin and iron oxide, and i) a content of a carbon element (A) existing on the toner surface measured by X-ray photoelectron spectroscopy. The ratio (B / A) of the content (B) of the iron element is less than 0.001, and ii) the projected area equivalent diameter of the toner is C, and the cross section of the toner is observed with a transmission electron microscope (TEM). When the minimum value of the distance between the iron oxide and the toner surface is D, D / C
50% by number or more of toners satisfying the relationship of ≦ 0.02; and iii) toner having an average circularity of 0.970 or more. 2. The toner according to claim 1, wherein the ratio (B / A) is less than 0.0005. 3. The toner according to claim 1, wherein the number of toners satisfying the relationship of D / C ≦ 0.02 is at least 65% by number. 4. The toner according to claim 1, wherein the number of toners satisfying the relationship of D / C ≦ 0.02 is 75% by number or more. 5. The toner according to claim 1, wherein the iron oxide is contained in an amount of 10 to 200 parts by mass based on 100 parts by mass of the binder resin. 6. The toner according to claim 1, wherein the iron oxide is contained in an amount of 20 to 180 parts by mass based on 100 parts by mass of the binder resin. 7. The toner has a weight average particle diameter of 2 to 10 μm.
7. The toner according to claim 1, wherein m is m. 8. The toner according to claim 1, wherein said toner has a weight average particle size of 3.5 to 8.
The toner according to any one of claims 1 to 6, wherein the particle diameter is μm. 9. The toner according to claim 1, wherein the toner contains hydrophobic silica treated with silicone oil. 10. The toner according to claim 1, wherein the iron oxide has been surface-treated with a coupling agent in an aqueous medium. 11. The toner according to claim 10, wherein the coupling agent is an alkyl trialkoxy silane coupling agent. 12. A ferromagnetic iron oxide prepared by adding an alkali to an aqueous ferrous salt solution, performing an oxidation reaction of ferrous hydroxide while heating, and adding an aqueous ferrous sulfate solution thereto. The toner according to claim 1, wherein the toner is iron oxide. 13. The iron oxide has a volume average particle size of 0.1 to 0.1.
The toner according to any one of claims 1 to 12, wherein particles having a particle diameter of 0.3 µm and 0.03 to 0.1 µm are 40% by number or less. 14. The iron oxide contains 30% by number or less of particles of 0.03 to 0.1 μm and 10% by number or less of particles of 0.3 μm or more. Item 14. The toner according to Item 13. 15. The iron oxide contains 30% by number or less of particles of 0.03 to 0.1 μm and 5% by number or less of particles of 0.3 μm or more. Item 14. The toner according to Item 13. 16. The toner according to claim 1, wherein the amount of the toner is 0.5 to the binder resin.
The toner according to any one of claims 1 to 15, wherein the toner contains about 50% by mass of wax. 17. The wax has a DSC curve measured by a differential scanning calorimeter at a temperature of 40 to 110 when heated.
17. The toner according to claim 16, having a maximum endothermic peak in a region of ° C. 18. The toner according to claim 1, wherein the toner is a toner produced by a suspension polymerization method.
The toner according to any one of the above. 19. A charging step of charging the electrostatic image carrier by a charging member to which a voltage is externally applied; an exposure step of forming an electrostatic latent image on the electrostatic image carrier by exposure;
A developing step of developing the electrostatic latent image with toner carried on a toner carrier to form a toner image; and a transfer step of transferring the toner image to a transfer material, wherein the toner is And i) the content of the iron element with respect to the content (A) of the carbon element present on the toner surface measured by X-ray photoelectron spectroscopy (A). The ratio (B / A) of the amount (B) is less than 0.001, ii) the projected area equivalent diameter of the toner is C, and the iron oxide and the toner are observed in a cross-sectional observation of the toner using a transmission electron microscope (TEM). When the minimum value of the distance from the surface is D, D / C
50% by number or more of toners satisfying a relationship of ≦ 0.02, and iii) an average circularity of the toner is 0.970 or more. 20. The method according to claim 19, wherein the developing step is a contact developing step of performing development while bringing an electrostatic image on the electrostatic image carrier into contact with the toner carried on the toner carrier. 2. The image forming method according to 1., 21. An image forming method according to claim 20, wherein said toner carrier is an elastic roller. 22. In the developing step, the moving speed of the surface of the toner carrier in the developing area is 1.05 to 3.0 times the moving speed of the surface of the electrostatic image carrier. 22. The image forming method according to claim 20, wherein 23. The surface roughness Ra of the toner carrier is:
21. The thickness is 0.2 to 3.0 [mu] m.
23. The image forming method according to any one of the above items. 24. The method according to claim 20, wherein in the developing step, the transfer residual toner remaining on the electrostatic image carrier after the transfer step is collected by the toner carrier. Image forming method. 25. The developing step, wherein an electrostatic image carrier and a toner carrier are arranged at a predetermined interval, and a toner layer is formed on the surface of the toner carrier with a thickness smaller than the interval.
20. The image forming method according to claim 19, further comprising a step of performing development by transferring the toner to an electrostatic latent image in a developing unit to which an AC bias is applied. 26. The image forming method according to claim 25, wherein a separation distance between the electrostatic image carrier and the toner carrier is 100 to 500 μm. 27. In the developing step, the speed difference between the surface of the electrostatic image carrier and the surface of the toner carrier in the developing area is:
26. The ratio is 1.02 to 3.0 times.
Or the image forming method according to 26. 28. The toner carrier according to claim 25, wherein the surface roughness Ra of the toner carrier is 0.2 to 3.5 μm.
28. The image forming method according to any one of the above items. 29. An AC bias having a peak-to-peak electric field strength of 3 × 10 ⁶ to 1 × 10 ⁷ V / m and a frequency of 10
The image forming method according to any one of claims 25 to 28, wherein the frequency is 0 to 5000 Hz. 30. The image forming method according to claim 19, wherein said charging step is a step of charging by bringing a charging member into contact with an electrostatic image carrier. 31. The transfer method according to claim 19, wherein the transfer step is a step of transferring the toner image to the transfer material by a transfer member that contacts the electrostatic image carrier via the transfer material. An image forming method according to any one of the above. 32. The charging step is a step of charging by bringing a charging member into contact with an electrostatic image carrier, and the developing step includes:
The electrostatic image carrier and the toner carrier are arranged at a fixed interval, a toner layer is formed on the surface of the toner carrier with a thickness smaller than the interval, and the toner layer is formed in a developing section to which an AC bias is applied. 20. The image forming method according to claim 19, wherein the developing is performed by transferring the toner to an electrostatic latent image. 33. A layer thickness of the toner carried on the toner carrier is regulated by a toner layer thickness regulating member, and the toner layer thickness regulating member is brought into contact with the toner carrier via the toner. 33. The image forming method according to claim 32, wherein: 34. The image forming method according to claim 33, wherein said toner layer thickness regulating member is an elastic member. 35. The image forming method according to claim 19, further comprising a fixing step of fixing the toner image transferred to the transfer material to the transfer material. 36. A charging step of charging the electrostatic image carrier by a charging member to which a voltage is externally applied; an exposure step of forming an electrostatic latent image on the electrostatic image carrier by exposure;
A developing step of developing the electrostatic latent image with toner carried on a toner carrier to form a toner image; and a transfer step of transferring the toner image to a transfer material, wherein the toner is , Any one of claims 2 to 19
An image forming method, wherein the toner is the toner described in (1).