JP5169487B2 - Protective layer forming apparatus, process cartridge, image forming apparatus, and image forming method - Google Patents

Description

The present invention, the protective layer forming device for forming an image-bearing member protective agent or Ranaru protective layer for protecting the surface of the image bearing member used in electrophotographic image formation surface of the image bearing member, said protecting agent The present invention also relates to a process cartridge, an image forming apparatus, and an image forming method using the protective layer forming apparatus.

  Image formation by electrophotography is possible by forming an electrostatic latent image by an electrostatic charge on an image carrier having a photosensitive layer containing a photoconductive substance and the like, and attaching a charged toner to the electrostatic latent image. A visual image is formed. This visible image is transferred to a recording medium such as paper and then fixed on the recording medium by heat, pressure, solvent gas, etc., and an output image is obtained.

  In such image formation, a two-component development method using frictional charging by stirring and mixing the toner and the carrier and a method of charging the toner without using a carrier by a method of charging the toner for visualization. It is roughly divided into a one-component development system. This one-component development method is further classified into a magnetic one-component development method and a non-magnetic one-component development method depending on whether or not a magnetic force is used to hold toner on the developing roller.

Conventionally, in a copying machine or a multi-function machine based on a copying machine that requires high speed and image reproducibility, the requirements for charging stability of the toner, start-up property, long-term stability of image quality, etc. Many component development methods are employed. On the other hand, one-component development systems are often used in small printers, facsimiles, and the like, which have great demands for space saving and cost reduction.
In recent years, in any of the development methods, the colorization of output images has progressed, and the demand for higher image quality and stabilization of image quality has become stronger than ever. In order to achieve such high image quality, the average particle size of the toner is reduced, the particle shape has no angular portion, and the toner has a more round shape.

  In addition, an electrophotographic image forming apparatus is generally charged uniformly while moving (rotating) an image carrier having a drum shape or a belt shape, regardless of the development method. A latent image pattern is formed on the image carrier, and the latent image pattern is converted into a visible image (toner image) with toner and transferred onto a recording medium. Then, the toner component that has not been transferred remains on the image carrier after the toner image is transferred to the recording medium. When these residuals are conveyed to the charging process as they are, the charging of the image carrier is prevented from being uniformly charged. Usually, after the transfer process, the toner remaining on the image carrier is removed by a cleaning blade or the like. Is removed by the cleaning means, and the surface of the image carrier is sufficiently cleaned, and then charging is performed.

  As described above, the surface of the image bearing member is subjected to various physical stresses and electrical stresses in each process such as charging, development, transfer, and cleaning, and the surface state changes with use time. Of these stresses, stress due to friction in the cleaning process wears the image carrier and causes scratches. In order to solve this problem, in order to reduce the frictional force between the image carrier and the cleaning blade, many proposals have been made on the supply, application and formation of the lubricant layer of the lubricant component. ing.

For example, in the prior art described in Patent Document 1, after applying a solid lubricant by an application roller, a leveling blade for leveling the lubricant on the image carrier is provided, and by setting the leveling blade to a specific hardness or higher, It is said that lubricant can be applied.
However, in the prior art described in Patent Document 1, since the solid solid lubricant is supplied to the surface of the scraped image carrier by a supply member such as a brush, it is illustrated in FIG. There are various sizes of lubricant particles. For this reason, in order to form a uniform lubricating layer, it is necessary to use a leveling blade having a relatively high hardness, and in order to make the lubricant scraped evenly, the pressing force is uniform. It was necessary to achieve high accuracy. That is, when the supply amount of the lubricant fluctuates, and particularly when the supply amount decreases, the leveling blade has a high hardness, so the stress applied to the image carrier increases, resulting in damage to the image carrier and damage to the image carrier. However, there is a risk of problems such as blade wear.

Further, in the prior art described in Patent Document 2, when supplying a solid solid lubricant to the surface of the image carrying member by scraping with a brush-like supply member, a flicking member is brought into contact with the brush to make the supply amount uniform. I am trying.
According to this prior art, it can be expected that the total supply amount will be uniform to some extent. However, even in this conventional technique, since a solid solid lubricant is used, the size of the scraped lubricant varies, and it is not always possible to ensure uniformity in the width direction.

  Further, in the prior art described in Patent Documents 3, 4, and 5, it has been proposed to stabilize the supply amount of the solid solid lubricant, but in order to stabilize the supply amount of the solid solid lubricant, Further, since additional members such as a lubricant swinging mechanism, a shaving member, and a temperature detector are required, the mechanism and control are complicated.

  Further, in the conventional technique described in Patent Document 6, it is proposed that the supply amount is stabilized over time by the configuration of the solid lubricant itself. However, even in this prior art, the solid lubricant is still in a solid configuration, and since it is used while scraping with a brush, the size of the scraped lubricant particles is not considered at all. The positional variation in supply amount cannot be resolved.

As described above, in order to protect the image carrier, it is necessary to form a protective layer that is as uniform as possible on the surface thereof. For this purpose, protective agent particles having the same size as possible are supplied to the surface of the image carrier. There is a need.
However, since the conventional application methods described in Patent Documents 1 and 2 and the like all supply a lubricant using a solid lubricant that is in a dense state, the solid lubricant When scraping off the surface of the surface, the size of the scraped particles tends to be uneven, and with the aging of the scraping member, the size of the scraped lubricant particles fluctuates and a stable protective layer is formed. It was difficult to form over a long period of time.
Further, in the prior art described in Patent Documents 3, 4, 5, etc., it is necessary to arrange a stabilizing member other than the lubricant supply member in order to stabilize the supply amount of the lubricant. It was a hindrance.
Furthermore, when the fatty acid metal salt powder and the solid lubricant powder are used in combination as a lubricant, the solid lubricant powder fills the filler in the solid when both are made solid by melt mixing or the like. As a result, the hardness of the lubricant solid is increased and the scraping property is hindered. Therefore, it has been very difficult to supply a stable lubricant.

On the other hand, in the prior arts described in Patent Document 7 and Patent Document 8, a method is proposed in which the lubricant is held in powder form and supplied in a fixed amount. According to this method, the size of the supplied lubricant particles can be stabilized over time by arranging the particle sizes in advance.
However, when supplying powder, the supply amount may not be stable because a positional deviation such as a left-right difference occurs in the lubricant powder depending on the inclination of the apparatus and the way of handling during conveyance. In order to make this constant, it is necessary to stir the lubricant powder with an agitator or the like and eliminate variations depending on the location, but this requires a large space and a stirring mechanism is required. The lubricant supply device tends to be large, which hinders downsizing of the image forming apparatus.

According to the prior art described in Patent Document 7, since there is no mechanism for making the powder as described above uniform in position, the supply amount in the width direction may be non-uniform.
Further, even with the configuration of the prior art described in Patent Document 8, when powder unevenness occurs in the lubricant reservoir, there is a possibility that uniform supply cannot be performed.
Furthermore, in the conventional techniques described in Patent Document 7 and Patent Document 8, when a plurality of types of lubricant powders are used in combination, only specific types of powders are consumed or retained if their specific gravity or flow performance is different. The composition ratio of the lubricant consumed during the period of use may vary, and stable lubricant performance may not be exhibited.

Moreover, in the prior art described in Patent Document 9, by using a fluororesin porous material as a lubricant, the amount of wear of the fluororesin can be moderately suppressed. It is said that the surface friction coefficient of the photosensitive drum can be reduced without damaging the surface of the photosensitive member because it is softer than that.
However, in general, a fluororesin has a high melting point and softening temperature, and it is necessary to use a large amount of energy to form a sintered body in order to produce a porous molded body. In such a porous body, the particle boundary is firmly bound, and thus the scraped particles are not loosened at the particle boundary and are likely to be uneven in size as in the case of the solid lubricant. As described above, with a porous lubricant using a fluororesin, it has been difficult to stably supply the lubricant to the surface of the image carrier.

  As described above, a protective agent (or lubricant) component containing a plurality of materials is uniformly and accurately supplied to the surface of the image carrier, and the surface of the image carrier is subjected to electrical stress in the charging process, rubbing of the cleaning member, and the like. Although protection from mechanical stress is an extremely important issue for extending the life of the image carrier, charging member, and cleaning member and stabilizing the image quality, it remains an unsolved issue. This is the current situation.

JP 2007-140391 A JP 2006-84878 A JP 2002-6679 A JP-A-9-90847 JP-A-9-138622 JP 2000-338819 A JP 2000-330443 A JP 2007-102038 A JP 2000-9838 A

An object of the present invention is to solve the above-described problems in the prior art and achieve the following objects.
That is, the present invention protects the image carrier from electrical stress due to charging or the like and mechanical stress due to sliding of the cleaning member, and the protective agent deteriorated by electrical stress affects the image quality and peripheral members. suitable for Nikuku, stable over time with a certain amount of feed is easily substantially protective layer forming device for forming a no material difference image-bearing member protective agent or Ranaru protective layer surface of the image bearing member providing news, before the process cartridge using Kiho Mamoruso forming apparatus, to provide an image forming apparatus and an image forming method, and an object.

Means for solving the above problems are as follows.
That is, the first means of the present invention is a protective layer forming apparatus for scraping the compacted image carrier protective agent to the image carrier with a protective agent supply member having a brush, the image carrier In the protective layer forming apparatus using at least a mixed powder containing a fatty acid metal salt powder and a solid lubricant powder as a protective agent for use ,
The number-based 50% particle diameter Da of zinc stearate as the fatty acid metal salt powder is 20 to 90 μm , and the number-based 50% particle diameter Db of boron nitride as the solid lubricant powder is 0.1. ～14Myuemu, the ratio of the particle diameters Da and Db, is Db / Da, 0 <Db / Da ≦ 0.4, the porosity of the image bearing member protective agent, 3 to 15% by volume, and the image bearing The weight ratio of zinc stearate and boron nitride contained in the body protecting agent is 70/30 to 95/5 .
According to a second means of the present invention, in the protective layer forming apparatus according to the first means, the protective agent for the image carrier is a 50% particle diameter Dc = 0.1 to 1.5 μm based on the number. It is characterized by containing fine particles .
According to a third means of the present invention, in the protective layer forming apparatus according to the first means or the second means, the pressing force is applied so that the protective agent for the image carrier is pressed against the protective agent supply member. and it is characterized in Rukoto to have a member.
According to a fourth means of the present invention, in the protective layer forming apparatus according to the third means, the protective layer is formed by thinning the protective agent for the image carrier supplied to the surface of the image carrier. It has a forming member .
According to a fifth aspect of the present invention, there is provided a process cartridge, comprising at least an image carrier and the protective layer forming apparatus according to the third or fourth means, wherein the image forming apparatus main body is attached to and detached from the main body. It is characterized by being possible .
According to a sixth means of the present invention, in the process cartridge according to the fifth means, the toner remaining on the surface of the image carrier is removed upstream of the protective layer forming device in the moving direction of the image carrier. It has the cleaning means to do.
According to a seventh aspect of the present invention, there is provided an image forming apparatus , wherein the image forming unit includes the process cartridge described in the fifth means or the sixth means .
According to an eighth aspect of the present invention, there is provided an image forming apparatus comprising: an image carrier; an electrostatic latent image forming unit that forms an electrostatic latent image on the image carrier; Development means for developing a visible image by using the image forming apparatus, transfer means for transferring the visible image to a recording medium directly or via an intermediate transfer member, and protection according to the third means or the fourth means a layer forming device, and a fixing unit configured to fix the transferred image on the recording medium is characterized in that it has at least.
Ninth means of the invention, Te image forming apparatus odor according to the eighth means, on the upstream side of the downstream side and the protective layer forming device from said transfer means of the movement direction of said image bearing member, said image It has a cleaning means for removing toner remaining on the surface of the carrier .
According to a tenth means of the present invention, in the image forming apparatus according to the eighth means or the ninth means, the electrostatic latent image forming means is disposed in contact with or close to the surface of the image carrier. It has a charging means .
The eleventh means of the present invention includes an electrostatic latent image forming step of forming an electrostatic latent image on an image carrier, and a developing step of developing the electrostatic latent image with toner to form a visible image. A transfer step of transferring the visible image directly to a recording medium or via an intermediate transfer member, and a first means or a second means on the surface of the image carrier after the transfer. It includes at least a protective layer forming step of forming a protective layer using a protective layer forming device and a fixing step of fixing the transferred image transferred onto the recording medium .

Hereinafter, the present invention will be described in more detail.
The protective agent for an image carrier of the present invention is “at least the protective agent for an image carrier, a protective agent supply member that supplies the protective agent for the image carrier to the surface of the image carrier, and the protective agent supply member for the image carrier. "Protection for an image carrier formed by compacting a mixed powder containing a fatty acid metal salt powder and a solid lubricant powder" used in a protective layer forming apparatus having a pressing force applying member that presses and contacts a protective agent In the “agent”, “the 50% particle diameter Da based on the number of fatty acid metal salt powders is 20 to 90 μm, and the porosity of the protective agent molded body for image carrier is 3 to 15% by volume”. Is a protective agent for an image carrier.

The protective agent for an image carrier of the present invention forms a uniform protective layer by forming a film on the surface of the image carrier at the same time or after the adhesion in the protective layer formation process in the image forming process in the image forming apparatus. . If the film formation is insufficient, the surface of the image carrier cannot be protected from electrical stress in the subsequent charging process.
In order to ensure the formation of the protective layer, it is necessary to stably supply the necessary and sufficient amount of the protective agent for the image carrier to the image carrier, but the image carrier is protected by a rubbing member such as a brush. When the agent is scraped off and supplied to the surface of the image carrier, the amount supplied and the size of the supplied powder strongly depend on the hardness and brittleness of the protective agent for the image carrier.

By the way, when the image carrier protective agent comprising the fatty acid metal salt and the solid lubricant as in the present invention is used in a solid, the solid lubricant particles are dispersed in the solid as described above, and the filler and As a result, the protective solid for the image carrier is extremely hardened. Therefore, in order to secure a sufficient supply amount, the frictional member such as a brush has to use a hard and hard material.
However, when the scraping member has a high rigidity and a hard material, when the scraped image carrier protective agent is supplied, the surface of the image carrier is scratched locally with a strong force. At the starting point, foreign matters such as toner may be attached or buried in streak-like scratches or indentations of the scratches, so-called filming may occur and appear as an abnormal image.
Conversely, if the pressing force of the rubbing member against the surface of the image carrier is weakened to the extent that local strong force is not applied to the surface of the image carrier, the contact area becomes sparse, so the surface of the image carrier is uniformly distributed. It becomes difficult to supply the protective agent for the image carrier.

  That is, the rigidity of the rubbing member cannot be increased as much as possible, and it is necessary to have a flexibility that does not damage the surface of the image carrier. Next, when such a rubbing member is used to sufficiently scrape off the above-described image carrier protective agent solid, it is necessary to strongly press the rubbing member against the surface of the image carrier protective agent. In this case, since a large force is always applied to the rubbing member, the scraping property of the rubbing member is likely to change with time, and there is a large difference in the scraping amount of the protective agent for the image carrier after the initial use and a certain period of time. It is difficult to stably protect the image carrier for a long period of time.

  Based on the above, a fatty acid metal salt and a solid lubricant are used in combination to stably and temporally supply a protective agent for an image carrier comprising a fatty acid metal salt and a solid lubricant onto the surface of the image carrier. Even so, the image carrier protective agent itself has a configuration in which the image carrier protective agent itself does not become too hard, in particular, a configuration in which the solid lubricant does not exhibit an effect of increasing the strength of the image carrier protective agent. There is a need.

According to the present invention, in a protective agent for an image carrier obtained by compacting a mixed powder containing a fatty acid metal salt powder and a solid lubricant powder, the number-based 50% particle diameter Da of the fatty acid metal salt powder is 20 ˜90 μm, and the porosity of the image bearing member protective agent molded body is 3 to 15% by volume. As a result, the fatty acid metal salt powder particles are compacted (consolidated) via particle boundaries having a scale comparable to the particle diameter. Further, the solid lubricant exists only in the vicinity of the particle boundary region of the dense fatty acid metal salt powder and is not dispersed inside the fatty acid metal salt powder particles. Therefore, the solid lubricant does not act as a filler, and the image carrier protecting agent does not become as hard as a solid.
Therefore, a sufficient amount of the protective agent for the image carrier using the fatty acid metal salt and the solid lubricant in combination without strongly pressing the rubbing member with high rigidity on the rubbing member or the protective agent for the image carrier. Can be stably supplied to the surface of the image carrier.
For this reason, the image forming apparatus including the image carrier can be maintained in a good state for a long period of time.

The smaller the particle size of the fatty acid metal salt powder is, the easier it is to loosen when it is scraped off by the rubbing member, so it is preferable to supply it to the surface of the image carrier, but the protective agent powder for the image carrier is too small. If the amount is too large, the powder may be sent to the electrostatic latent image forming step as it is without forming a protective layer of the fatty acid metal salt component on the surface of the image carrier. In order to prevent this and form a reliable protective layer, the size of the fatty acid metal salt powder may be 20 μm or more in terms of the number-based 50% particle diameter.
On the other hand, if the fatty acid metal salt powder is too large, the internal strength of the particles themselves is considered to be easily scraped off by the protective agent at the normal time, but it is more easily peeled off at the final stage when individual fatty acid metal salt particles are consumed. The particles are peeled off at the particle boundary, and larger particles than the normally supplied fatty acid metal salt particles are mixed and supplied. The presence of such particles having a large particle size may cause local excess or deficiency of the supply amount of the protective agent component, and may cause the protective layer to become non-uniform. In order to prevent this and form a reliable protective layer, the size of the fatty acid metal salt powder may be 90 μm or less in terms of the number-based 50% particle diameter.

The porosity is an index representing the ratio of gas (generally air) in the apparent volume occupied by the molded article of the image carrier protective agent. It refers to the proportion of voids in the protective agent molded product.
This ratio can be measured in accordance with, for example, the method shown in JIS K7138 “Rigid Foamed Plastic—How to Obtain Open Cell Ratio and Closed Cell Ratio”.
It is better to measure the porosity of the image carrier protective agent molded body as much as possible, but if it is up to about 3 cm in length, the bar-shaped molded body is cut and used as a measurement sample. However, the porosity can be obtained with sufficient accuracy without correcting the influence of the surface bubbles.

The protective layer forming apparatus of the present invention includes a protective agent for an image carrier, a protective agent supply member that supplies the protective agent for the image carrier to the surface of the image carrier, and presses the protective agent for the image carrier to the protective agent supply member And a pressing force applying member to be brought into contact with. Since the protective agent for an image carrier of the present invention has a porous structure having moderate voids, it has a structure that can be easily separated into protective powder of an equal size. Therefore, the image bearing member protective agent is easily and evenly scraped off by the supply member. As a result, the protective agent for the image carrier is quickly supplied to the surface of the image carrier.
Therefore, a protective layer having an appropriate film strength is quickly formed on the surface of the image carrier.

Since the process cartridge of the present invention has the protective layer forming apparatus of the present invention having the protective agent for the image carrier, the replacement interval of the process cartridge can be set to be extremely long. And the amount of waste can be greatly reduced. In particular, when the image carrier includes a thermosetting resin in the outermost surface layer, an image containing the thermosetting resin is prevented by preventing the image carrier from being deteriorated by an electrical stress with a protective agent for the image carrier. The durability of the carrier against mechanical stress can be continuously expressed over a long period of time.
In addition, since the protective agent for an image carrier of the present invention quickly forms a film on the image carrier, the charging member disposed in contact or in close proximity is not contaminated by the flying of the powder, and the aging of the charging device is continued. Change can be reduced. For this reason, it becomes easy to reuse process cartridge components such as an image carrier and a charging member, and the amount of waste can be further reduced.

Since the image forming apparatus of the present invention includes the protective layer forming apparatus of the present invention having the above-mentioned protective agent for the image carrier, the image carrier can be continuously used without being exchanged for a very long time. In particular, when the image carrier includes a thermosetting resin in the outermost surface layer, an image containing the thermosetting resin is prevented by preventing the image carrier from being deteriorated by an electrical stress with a protective agent for the image carrier. The durability of the carrier against mechanical stress can be continuously expressed over a long period of time. As a result, the durability of the image carrier can be increased to a level where it can be used without substantial replacement.
Further, in the charging device arranged in contact with or close to the surface of the image carrier, the electrical stress tends to be large because the discharge region exists in the very vicinity of the image carrier. If the image forming apparatus of the present invention in which is formed, the image carrier can be used without being exposed to electrical stress.
In addition, since the surface state of the image carrier can be made extremely small due to the effect of the protective layer formed, the average quality is such that the quality of the cleaning changes sensitively to the state change of the image carrier. Even a toner having a large degree of circularity or a toner having a small average particle diameter can be stably cleaned over a long period of time.

According to the present invention, the problems in the prior art can be solved, and since the solid molded body has high hardness, a protective agent for an image carrier that tends to vary in how it is scraped spatially and temporally, since it stably supplied to the image bearing member, it is possible to provide a protective layer forming device Ru coercive Mamorusu the image bearing member from mechanical stress by rubbing or the like of the electric stress and the cleaning member by the charging or the like, Can provide a process cartridge, an image forming apparatus, and an image forming method using the same.

  Hereinafter, the best mode for carrying out the present invention will be described in detail.

(Protective agent for image carrier)
The protective agent for an image carrier of the present invention includes a fatty acid metal salt powder and a solid lubricant powder, the 50% particle diameter Da based on the number of the fatty acid metal salt powder is 20 to 90 μm, and the image carrier The porosity of the body protective agent molded body is 3 to 15% by volume.

In order to protect the image carrier, it is necessary to supply a certain amount of the protective agent for the image carrier onto the image carrier in a sufficiently uniform size using a protective agent supply member. For this purpose, it is preferable that the supply amount and particle size distribution state do not depend on the material properties of the protective agent for the image carrier, and the protective agent for the image carrier is a powder obtained by pressure-forming a powdery protective agent raw material. A consolidated body is preferred.
As a result, the structure of the molded body is maintained at the boundary (grain boundary) between the protective agent particles by a binding force mainly composed of the cohesive force between particles while maintaining a discontinuous state. Such a compact formed by agglomeration of particles is easily loosened to a powder having the original particle diameter with a relatively gentle force, and a necessary amount of protective agent powder having a uniform particle diameter can be supplied.
Further, the image carrier protecting agent contains at least a fatty acid metal salt and a solid lubricant. By supplying this protective agent powder as particles of uniform size to the surface of the image carrier, a protective film having good lubricity can be formed quickly and uniformly.

  The fatty acid metal salt is not particularly limited, but long-chain fatty acids such as stearic acid, palmitic acid, and melicic acid, alkali metal ions such as sodium and potassium, alkaline earth metal ions such as magnesium and calcium, aluminum And compounds in which metal ions such as zinc are bonded. Among these, zinc stearate can be preferably used because it can easily obtain a raw material powder having a molecular structure with high crystallinity and a uniform particle diameter.

  The solid lubricant is not particularly limited, and examples thereof include boron nitride, graphite, molybdenum disulfide, graphite fluoride, melamine cyanurate, and calcium fluoride. Among these, boron nitride is preferably used in combination with an excellent lubricating action because it has a plate-like structure, is easily oriented on the surface of the image carrier, is white, and has high electrical resistance and stability.

Also, by making the size of the solid lubricant powder particles smaller than the size of the fatty acid metal salt powder particles, the solid lubricant is supported on the surface of the fatty acid metal salt particles by mixing the raw materials. This makes it possible for the solid lubricant to be evenly present in the vicinity of the grain boundary of the fatty acid metal salt powder, and at the same time, the fatty acid metal salt particles are difficult to come into direct contact with each other. As a result, the local pressure concentration is relaxed, and the internal density variation of the protective agent molded body for the image carrier can be suppressed.
The ratio of 50% particle diameter Da based on the number of fatty acid metal salt powders to 50% particle diameter Db based on the number of solid lubricant powders, Db / Da is 0 <Db / Da ≦ 0.4, and When Db is in the range of 0.1 to 14 μm, the density variation of the protective agent molded body for the image carrier can be sufficiently suppressed, and therefore, it can be preferably used.

Further, after the solid lubricant is supplied onto the image carrier, the self-lubricating property assists the peripheral fatty acid metal salt to be spread and thinned in the protective layer forming part, and the image carrier It is considered that the stability of the protective layer formation by the fatty acid metal salt is improved.
If the solid lubricant content is too high, the supply amount of fatty acid metal salt is relatively reduced, so that a uniform protective layer is hardly formed. Conversely, if the solid lubricant content is too low, a thin layer is formed. In some cases, the auxiliary effect for crystallization is not sufficiently developed.
If the weight ratio of the fatty acid metal salt to the solid lubricant contained in the image carrier protective agent is in the range of 70/30 to 95/5, a sufficiently uniform image carrier protective layer can be formed quickly. Can be preferably used.

(Polished fine particles)
The above-mentioned protective agent for an image bearing member is a composition having an auxiliary role in a protective layer forming process and a protective layer removing process. It is preferable to include. When the protective agent powder spreads on the image carrier to form a protective layer, these fine particles are rolled by themselves or moved while sliding, thereby extending the protective agent powder thinly and evenly. It is preferably used in combination in order to assist the rapid formation of the protective agent layer. Moreover, it is preferable that the protective agent which received the electrical stress in the protective agent layer is removed as soon as possible, and is replaced with the protective agent which has not received the stress newly. By using the fine particles together, the protective agent component deteriorated due to stress can be entangled with the fine particles and quickly removed from the system, which is combined with the stable supply of the protective agent powder. Metabolism is performed and the image carrier can be protected very stably.
The fine particles are not particularly limited as long as they do not inhibit the structure defined in the present application. For example, aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, cerium oxide, strontium titanate, metasilicate Metal oxide fine particles such as magnesium acid aluminate, metal double oxide fine particles, and hard organic fine particles represented by silicone resin particles can be used.

(Other compounds)
In addition, as other protective agent-added materials, powdered waxes can also be preferably used.
Examples of waxes include aliphatic saturated hydrocarbons, aliphatic unsaturated hydrocarbons, alicyclic saturated hydrocarbons, hydrocarbons classified as alicyclic unsaturated hydrocarbons and aromatic hydrocarbons, carnauba wax, rice bran wax, Examples include plant natural waxes such as candelilla wax and animal natural waxes such as beeswax and snow wax. These may be used individually by 1 type and may use 2 or more types together.
In particular, aliphatic saturated hydrocarbons and alicyclic saturated hydrocarbons, in which the bonds in the molecule consist only of low-reactivity and stable saturated bonds, are preferred, among which hydrocarbon waxes such as normal paraffins, isoparaffins and cycloparaffins are added. It is preferably used in terms of stability over time because the reaction hardly occurs and is chemically stable, and hardly causes an oxidation reaction in the actual air.

  In particular, by using a hydrocarbon wax containing at least one of Fischer-Tropsch wax and polyethylene wax as a relatively hard wax, the durability of the protective layer itself can be increased, so that it is formed on the surface of the image carrier. Since the protection of the image carrier can be realized without making the thickness of the protective layer excessive, it is more preferable.

Further, since the protective agent layer formed on the surface of the image carrier as described above is exposed to electrical stress and deteriorates, if the molecular weight of the wax is too small, a sufficient protective effect may not be exhibited.
On the other hand, when the molecular weight of the wax is too large, a large shearing force is required when forming the protective agent component for the image carrier on the image carrier, so that an equivalent protective film may not be formed. .
For this reason, since the protective effect can be surely expressed by setting the molecular weight of the wax in the range of 350 to 850 on the basis of the weight average molecular weight Mw, the molecular weight is preferably 400 to 800.

  In addition to this, an amphiphilic organic compound such as a surfactant is added as an additive to increase the affinity between the protective agent for the image carrier and the surface of the image carrier and assist in forming the protective agent layer. You may use together.

In order to mold the image carrier protecting agent of the present invention into a certain shape, for example, a prismatic shape or a cylindrical shape, a dry molding method, which is one of powder molding methods, is used.
As a typical example of this dry molding method, the uniaxial pressure molding method can be generally performed by the following procedure.

1. A predetermined amount of a protective agent raw material powder having a certain number average particle diameter and comprising at least a fatty acid metal salt and a solid lubricant is weighed.
2. Each raw material powder is put into a mixer such as a mixer or a blender and mixed for a certain period of time. At this time, the raw material powder may be added in multiple stages.
3. After mixing, a predetermined amount of the protective material raw material powder for the image carrier is put into a mold having a predetermined shape.
4). The powder put in by a pressing die is pressurized to create a powder compact with a specific porosity.
The powder compacted body is removed from the mold to form a porous molded body of the protective agent for the image carrier.
5. Thereafter, the shape of the protective agent for the image carrier may be adjusted by cutting or the like.
However, at this time, if the heating element is pressed to increase the surface smoothness, it is not preferable because the surface protective particles are fused and coarsened.

Further, if necessary, the powder compacted body may be cured at a predetermined temperature for a certain period of time and then cooled by standing or cooling to adjust the binding force at the raw material powder interface.
However, excessive temperature and long-term curing are not preferable because the bonding between particles is strengthened and the sintered state is shifted to an excessively sintered state.

  The mold is preferably a metal mold such as steel, stainless steel or aluminum because of its good dimensional accuracy and good thermal conductivity. The inner wall surface of the mold may be coated with a small amount of release agent such as fluorine resin or silicone resin in order to improve the releasability.

(Protective layer forming device)
The protective layer forming apparatus of the present invention includes a protective agent for an image carrier, a protective agent supply member that supplies the protective agent for the image carrier to the surface of the image carrier, and presses the protective agent for the image carrier to the protective agent supply member At least a pressing force applying member to be brought into contact with, and further having other means as required.

The protective layer forming apparatus includes: a pressing force applying member that presses the image carrier protective agent to contact the protective agent supply member; and a protective agent supply member that supplies the image carrier protective agent to the surface of the image carrier. A protective layer forming member for forming a protective layer by thinning the supplied protective agent for the image carrier, and further having other configurations as necessary.
In addition, when the protective layer forming apparatus includes the protective layer forming member, the protective layer forming member may also serve as a cleaning member. It is preferable to remove the residue mainly composed of toner on the carrier so that the residue does not enter the protective layer.

Here, FIG. 1 is a schematic configuration diagram illustrating a main part of an image forming unit including the protective layer forming apparatus 2 of the present invention.
A protective layer forming apparatus 2 disposed opposite to an image carrier (for example, a photoconductor drum) 1 is formed by forming a protective agent for protecting the image carrier 1 into a columnar shape, a rectangular column shape, a hexagonal column shape, or the like. A protective agent 21 for the image carrier, a protective agent supply member 22 that has a brush 22a in contact with the protective agent 21 and supplies the protective agent transferred from the protective agent 21 to the brush 22a to the image carrier 1, and a protective agent 21 Is pressed against the brush 22a of the protective agent supply member 22 to transfer the protective agent to the brush 22a of the protective agent supply member 22, and the protective agent supplied onto the image carrier by the protective agent supply member 22 Are mainly composed of a protective layer forming member 24 for thinning the protective layer, a protective agent support member 25 for supporting the protective agent 21 so as not to swing back and forth, and the like. Further, the image bearing member protective agent 21 used in the present invention is produced by the above-described dry molding method or the like.

The protective agent 21 for an image carrier of the present invention is in contact with, for example, a brush-like protective agent supply member 22 by a pressing force from a pressing force applying member 23 formed of a member such as a spring or a spring. The brush 22a of the protective agent supply member 22 rotates and rubs with the image carrier 1 with a linear velocity difference. At this time, the image carrier protective agent 21 held on the surface of the protective agent supply member is transferred to the surface of the image carrier. To supply.
Since the image carrier protective agent 21 supplied to the surface of the image carrier may not be a sufficient protective layer upon supply depending on the selection of the material type, in order to form a more uniform protective layer, for example, in the form of a blade And a protective layer forming member 24 having a pressing member 24b such as a spring or a spring for pressing the blade-like member 24a against the surface of the photosensitive drum 1, and the protective layer on the surface of the image carrier It becomes.

The image carrier 1 on which the protective layer is formed has, for example, a small gap by contacting or approaching a charging roller 3 to which a DC voltage or a voltage obtained by superimposing an AC voltage is applied by a high voltage power source (not shown). The image carrier is charged by the discharge. At this time, a part of the protective layer is decomposed or oxidized due to electrical stress, and air discharge products adhere to the surface of the protective layer, resulting in a deteriorated product.
The deteriorated protective agent for the image carrier is removed by the cleaning mechanism together with the components such as the toner remaining on the image carrier by an ordinary cleaning mechanism. Such a cleaning mechanism may be used also as the above-described protective layer forming member. However, the function of removing the residue on the surface of the image carrier and the function of forming the protective layer are based on an appropriate member rubbing state. The functions are separated, and as shown in FIG. 1, a cleaning member (cleaning blade) 41 is provided upstream of the image carrier protective agent supply unit in the moving direction (rotation direction) of the image carrier 1 as shown in FIG. It is preferable to provide the cleaning means 4 including the cleaning pressing mechanism 42 and the like.

  The material of the blade-like member 24a used for the protective layer forming member 24 is not particularly limited and can be appropriately selected from materials known as cleaning blade materials according to the purpose. For example, urethane rubber, hydrin rubber , Silicone rubber, fluorine rubber and the like. These may be used individually by 1 type and may use 2 or more types together. In these blades, the contact portion with the image carrier may be coated or impregnated with a low coefficient of friction material. Moreover, in order to adjust the hardness of an elastic body, you may disperse fillers, such as an organic filler and an inorganic filler.

The blade-like member 24a made of a cleaning blade material or the like is fixed to the blade support 24c by an arbitrary method such as adhesion or fusion so that the tip can be pressed against the surface of the image carrier. The thickness of the blade-like member 24a is not uniquely defined by the balance with the force applied by pressing, but is preferably 0.5 to 5 mm, and more preferably 1 to 3 mm.
Further, the length of the cleaning blade that protrudes from the support 24c and can bend, that is, the so-called free length, is not uniquely defined in consideration of the force applied by pressing in the same manner. 2-10 mm is more preferable.

  As another configuration of the blade-like member 24a for forming the protective layer, a coating layer of resin, rubber, elastomer or the like is provided on the surface of an elastic metal blade such as a spring plate via a coupling agent or a primer component as necessary. It may be formed by a method such as coating, dipping, etc., and if necessary, it may be subjected to thermosetting, and if necessary, it may be subjected to surface polishing or the like.

The coating layer contains at least a binder resin and a filler, and further contains other components as necessary.
The binder resin is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include fluorine resins such as PFA, PTFE, FEP, and PVdF; silicone elastomers such as fluorine rubber and methylphenyl silicone elastomer; Is mentioned.

  The thickness of the elastic metal blade is preferably 0.05 to 3 mm, more preferably 0.1 to 1 mm. In the elastic metal blade, in order to suppress twisting of the blade, a process such as bending may be performed in a direction substantially parallel to the support shaft after the attachment.

  The force that presses the image carrier 1 with the protective layer forming member 24 is sufficient for the image carrier protective agent 21 to spread and become a protective layer, and the linear pressure is preferably 5 to 80 gf / cm. 10-60 gf / cm is more preferable.

A brush-like member 22 a is preferably used as the protective agent supply member 22. In this case, in order to suppress mechanical stress on the surface of the image carrier, it is preferable that the brush fiber has flexibility. The material of the flexible brush fiber is not particularly limited and may be appropriately selected depending on the intended purpose. For example, polyolefin resin (for example, polyethylene, polypropylene); polyvinyl resin or polyvinylidene resin (for example, Polystyrene, acrylic resin, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether, polyvinyl ketone); vinyl chloride-vinyl acetate copolymer; styrene-acrylic acid copolymer; styrene- Butadiene resin; fluororesin (eg, polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, polychlorotrifluoroethylene); polyester; nylon; acrylic; rayon; ; Polycarbonate; phenolic resins; amino resins (e.g. urea - formaldehyde resins, melamine resins, benzoguanamine resins, urea resins, polyamide resins).
In order to adjust the degree of bending, for example, diene rubber, styrene-butadiene rubber (SBR), ethylene propylene rubber, isoprene rubber, nitrile rubber, urethane rubber, silicone rubber, hydrin rubber, norbornene rubber, etc. may be combined. .

The support 22b of the brush 22a of the protective agent supply member 22 includes a fixed type and a rotatable roll. Examples of the roll-shaped supply member include a roll brush obtained by winding a tape having brush fibers piled around a metal core bar in a spiral shape. The brush fiber has a fiber diameter of about 10 to 500 μm, the length of the brush fiber is 1 to 15 mm, and the brush density is 10,000 to 300,000 per square inch (1.5 × 10 ^{7 to} 4.5 per square meter). × 10 ⁸ ) is preferable.

  The protective agent supply member 22 is preferably made of a material having a high brush density in terms of supply uniformity and supply stability, and one fiber is made from several to several hundreds of fine fibers. It is preferable to do. For example, bundling 50 fine fibers of 6.7 decitex (6 denier), such as 333 decitex = 6.7 decitex × 50 filament (300 denier = 6 denier × 50 filament), and implanting as one fiber Is preferred.

  Moreover, you may provide a coating layer in the brush surface for the purpose of stabilizing the surface shape, environmental stability, etc. of a brush as needed. As a component constituting the coating layer, it is preferable to use a coating layer component that can be deformed according to the bending of the brush fiber. The coating layer component is not particularly limited as long as it is a material that can maintain flexibility, and can be appropriately selected according to the purpose. For example, polyethylene, polypropylene, chlorinated polyethylene, chlorosulfonated polyethylene, etc. Polyolefin resin: Polystyrene such as polystyrene, acrylic (for example, polymethyl methacrylate), polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether, polybiliketone, or polyvinylidene resin such as polyvinyl chloride-acetic acid Vinyl copolymer; silicone resin composed of organosiloxane bonds or modified products thereof (modified products such as alkyd resin, polyester resin, epoxy resin, polyurethane resin, etc.); Fluororesins such as oloalkyl ether, polyfluorovinyl, polyfluorovinylidene, polychlorotrifluoroethylene; polyamides; polyesters; polyurethanes; polycarbonates; amino resins such as urea-formaldehyde resins; epoxy resins or composite resins thereof It is done.

(Process cartridge)
Next, an embodiment of a process cartridge according to the present invention will be described.
The process cartridge of the present invention comprises at least the image carrier and the protective layer forming apparatus 2 of the present invention, and further, if necessary, charging means, exposure means, developing means, transfer means, cleaning means, static elimination. It has other means such as means.
The process cartridge of the present invention can be detachably provided in various electrophotographic apparatuses, and is preferably provided detachably in the image forming apparatus of the present invention described later.

Here, FIG. 2 is a schematic cross-sectional view for explaining an outline of a configuration example of a process cartridge using the protective layer forming apparatus of the present invention. This process cartridge is an image forming unit of the image forming apparatus according to the present invention. 10 is detachably provided.
An image forming unit 10 shown in FIG. 2 includes an image carrier (for example, a photosensitive drum) 1, a charging device (charging roller in the illustrated example) 3 that is a charging unit that charges the image carrier 1, and a charged image. An electrostatic latent image forming means (not shown) for forming an electrostatic latent image by irradiating the carrier 1 with a laser beam L or the like, and developing the electrostatic latent image on the image carrier 1 with toner to make it visible A developing device 5 which is a developing means for forming an image (toner image), a transfer means 6 for transferring a toner image on the image carrier 1 to a transfer medium (recording medium such as paper or an intermediate transfer body) 7, and after transfer The cleaning device 4 is a cleaning unit that removes toner remaining on the surface of the image carrier 1, and the protective layer forming device 2 is disposed in a portion from the cleaning device 4 to the charging device 3. The image forming unit 10 is configured using a process cartridge 11 in which a protective layer forming device 2, a charging device 3, a developing device 5, and a cleaning device 4 are integrally provided in a cartridge together with the image carrier 1. Yes. In the present embodiment, the cleaning device 4 cleans the surface of the photosensitive member before supplying the protective agent so that the protective agent is satisfactorily applied. Therefore, the moving direction of the image carrier 1 ( It is provided downstream of the transfer means 6 in the rotation direction) and upstream of the protective layer forming apparatus 2.

In the process cartridge 11, the protective layer forming device 2 disposed facing the photosensitive drum as the image carrier 1 includes an image carrier protective agent 21, a protective agent supply member 22, a pressing force applying member 23, It comprises a protective layer forming member 24, a protective agent support member 25, and the like.
Further, the image carrier 1 has a surface on which the protective agent for the image carrier and the toner component partially deteriorated after the transfer process remain, but the surface residue is cleaned by the cleaning member 41 of the cleaning device 4. To be cleaned.
In FIG. 2, the cleaning member 41 is abutted at an angle similar to a so-called counter type (leading type). In addition, although the blade 24a of the protective layer forming member 24 is not a counter type in the illustrated example, the blade 24a may be abutted at an angle similar to the counter type.

The image carrier protective agent 21 is applied from the protective agent supply member 22 of the protective layer forming device 2 to the surface of the image carrier from which the toner remaining on the surface and the deteriorated protective agent for the image carrier are removed by the cleaning device 4. The protective layer forming member 24 forms a film-like protective layer. At this time, the protective agent 21 for the image carrier used in the present invention can stably supply the necessary and sufficient amount to the surface of the image carrier with good controllability, so that the surface of the image carrier can be efficiently protected for a long period of time. The progress of the deterioration of the image carrier itself can be prevented.
The image carrier 1 having the protective layer formed in this way is charged by the charging device (charging roller) 3, and then an electrostatic latent image is formed by exposure L such as a laser, and is developed by the developing device 5 to be visible. An image is formed and transferred to a transfer medium (recording medium such as paper or an intermediate transfer member) 7 by transfer means (transfer roller or the like) 6 outside the process cartridge.

  As described above, the process cartridge 11 of the present invention has an excellent tolerance for fluctuations in the surface state of the image carrier, and has a configuration in which fluctuations in charging performance to the image carrier are highly suppressed. By using the cartridge 11 in the image forming unit of the image forming apparatus, it is possible to stably form an extremely high quality image over a long period of time.

(Image forming apparatus and image forming method)
The image forming apparatus of the present invention includes an image carrier, an electrostatic latent image forming unit, a developing unit, a transfer unit, a protective layer forming unit (the protective layer forming device 2 of the present invention described above), and a fixing unit. At least, preferably a cleaning means, and other means appropriately selected as necessary, for example, a static elimination means, a recycling means, a control means and the like.
The image forming method of the present invention includes at least an electrostatic latent image forming step, a developing step, a transfer step, a protective layer forming step, and a fixing step, preferably including a cleaning step, and further appropriately as necessary. It includes other selected processes such as a static elimination process, a recycling process, and a control process.

  The image forming method of the present invention can be preferably carried out by the image forming apparatus of the present invention, the electrostatic latent image forming step can be performed by the electrostatic latent image forming means, and the developing step is the developing The transfer step can be performed by the transfer unit, the protective layer forming step can be performed by the protective layer forming unit (the protective layer forming apparatus 2 of the present invention described above), The fixing step can be performed by the fixing unit, and the other steps can be performed by the other unit.

<Electrostatic latent image forming step and electrostatic latent image forming means>
The electrostatic latent image forming step is a step of forming an electrostatic latent image on the image carrier.
-Image carrier-
The image carrier (sometimes referred to as “electrostatic latent image carrier” or “photoreceptor”) is not particularly limited in terms of material, shape, structure, size, etc., and is appropriately selected from known ones. The shape is preferably a drum shape, and examples of the material include inorganic photoconductors such as amorphous silicon and selenium, and organic photoconductors such as polysilane and phthalopolymethine.

The image carrier (photoreceptor) used in the image forming apparatus of the present invention has a conductive support and at least a photosensitive layer on the conductive support, and further has other layers as necessary. It becomes.
As the photosensitive layer, a single layer type in which a charge generation material and a charge transport material are mixed, a forward layer type in which a charge transport layer is provided on the charge generation layer, or a charge generation layer is provided on the charge transport layer. There is a reverse layer type. In order to improve the mechanical strength, abrasion resistance, gas resistance, cleaning property, etc. of the photoreceptor, an outermost surface layer can be provided on the photosensitive layer. An undercoat layer may be provided between the photosensitive layer and the conductive support. Moreover, an appropriate amount of a plasticizer, an antioxidant, a leveling agent or the like can be added to each layer as necessary.

The conductive support is not particularly limited as long as it has a volume resistance of 1.0 × 10 ¹⁰ Ω · cm or less, and can be appropriately selected according to the purpose. For example, aluminum, Metals such as nickel, chromium, nichrome, copper, gold, silver and platinum, metal oxides such as tin oxide and indium oxide, film or cylindrical plastic, paper coated or aluminum by vapor deposition or sputtering A plate made of aluminum alloy, nickel, stainless steel or the like, and a tube processed into a drum shape by a method such as extrusion or drawing, and then subjected to surface treatment such as cutting, superfinishing, or polishing can be used.

The drum-shaped support preferably has a diameter of 20 to 150 mm, more preferably 24 to 100 mm, and still more preferably 28 to 70 mm. When the diameter of the drum-shaped support is less than 20 mm, it may be physically difficult to arrange each step of charging, exposure, development, transfer, and cleaning around the drum. When the diameter exceeds 150 mm, The image forming apparatus may become large. In particular, when the image forming apparatus is a tandem type, since it is necessary to mount a plurality of photoconductors, the diameter is preferably 70 mm or less, and more preferably 60 mm or less.
Further, an endless nickel belt or an endless stainless steel belt as disclosed in JP-A-52-36016 can also be used as the conductive support.

The undercoat layer of the photoconductor may be composed of a single layer or a plurality of layers. For example, (1) the resin is the main component, and (2) the white pigment and the resin are the main components. And (3) a metal oxide film obtained by chemically or electrochemically oxidizing the surface of a conductive substrate. Among these, those containing a white pigment and a resin as main components are preferable.
Examples of the white pigment include metal oxides such as titanium oxide, aluminum oxide, zirconium oxide, and zinc oxide. Among these, titanium oxide is particularly preferable because it is excellent in preventing injection of charges from the conductive support.
Examples of the resin include thermoplastic resins such as polyamide, polyvinyl alcohol, casein, and methyl cellulose; thermosetting resins such as acrylic, phenol, melamine, alkyd, unsaturated polyester, and epoxy. These may be used individually by 1 type and may use 2 or more types together.
There is no restriction | limiting in particular in the thickness of the said undercoat layer, According to the objective, it can select suitably, 0.1-10 micrometers is preferable and 1-5 micrometers is more preferable.

  Examples of the charge generation material in the photosensitive layer include monoazo pigments, bisazo pigments, trisazo pigments, tetrakisazo pigments and other azo pigments, triarylmethane dyes, thiazine dyes, oxazine dyes, xanthene dyes, Cyanine dyes, styryl dyes, pyrylium dyes, quinacridone pigments, indigo pigments, perylene pigments, polycyclic quinone pigments, bisbenzimidazole pigments, indanthrone pigments, squarylium pigments, phthalocyanine pigments, etc. Organic pigments or dyes; selenium, selenium-arsenic, selenium-tellurium, cadmium sulfide, zinc oxide, titanium oxide, amorphous silicon, and other inorganic materials. These may be used individually by 1 type and may use 2 or more types together.

  Examples of the charge transport material in the photosensitive layer include anthracene derivatives, pyrene derivatives, carbazole derivatives, tetrazole derivatives, metallocene derivatives, phenothiazine derivatives, pyrazoline compounds, hydrazone compounds, styryl compounds, styryl hydrazone compounds, enamine compounds, butadiene compounds, distyryl. Examples thereof include compounds, oxazole compounds, oxadiazole compounds, thiazole compounds, imidazole compounds, triphenylamine derivatives, phenylenediamine derivatives, aminostilbene derivatives, and triphenylmethane derivatives. These may be used individually by 1 type and may use 2 or more types together.

  As the binder resin used to form the photosensitive layer, it is electrically insulating and may be a known thermoplastic resin, thermosetting resin, photocurable resin, photoconductive resin, or the like. it can. Examples of the binder resin include polyvinyl chloride, polyvinylidene chloride, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, ethylene-vinyl acetate copolymer, polyvinyl butyral, Polyvinyl acetal, polyester, phenoxy resin, (meth) acrylic resin, polystyrene, polycarbonate, polyarylate, polysulfone, polyethersulfone, ABS resin and other thermoplastic resins, phenol resin, epoxy resin, urethane resin, melamine resin, isocyanate Examples thereof include thermosetting resins such as resins, alkyd resins, silicone resins, thermosetting acrylic resins, polyvinyl carbazole, polyvinyl anthracene, and polyvinyl pyrene. These may be used individually by 1 type and may use 2 or more types together.

Examples of the antioxidant include phenolic compounds, paraphenylenediamines, organic sulfur compounds, and organic phosphorus compounds.
Examples of the phenol compound include 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, stearyl-β- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate, 2,2'-methylene-bis- (4-methyl-6-t-butylphenol), 2,2'-methylene-bis- (4-ethyl- 6-t-butylphenol), 4,4′-thiobis- (3-methyl-6-tert-butylphenol), 4,4′-butylidenebis- (3-methyl-6-tert-butylphenol), 1,1,3 -Tris- (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxy Ben ) Benzene, tetrakis- [methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane, bis [3,3′-bis (4′-hydroxy-3 ′) -T-butylphenyl) butyric acid] cricol ester, tocopherols and the like.
Examples of the paraphenylenediamines include N-phenyl-N′-isopropyl-p-phenylenediamine, N, N′-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl- Examples include p-phenylenediamine, N, N′-di-isopropyl-p-phenylenediamine, N, N′-dimethyl-N, N′-di-t-butyl-p-phenylenediamine, and the like.
Examples of the hydroquinones include 2,5-di-t-octyl hydroquinone, 2,6-didodecyl hydroquinone, 2-dodecyl hydroquinone, 2-dodecyl-5-chlorohydroquinone, 2-t-octyl-5-methyl. Examples include hydroquinone and 2- (2-octadecenyl) -5-methylhydroquinone.
Examples of the organic sulfur compounds include dilauryl-3,3′-thiodipropionate, distearyl-3,3′-thiodipropionate, ditetradecyl-3,3′-thiodipropionate, and the like. .
Examples of the organic phosphorus compounds include triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, tri (2,4-dibutylphenoxy) phosphine, and the like.
These compounds are known as antioxidants such as rubbers, plastics and fats and oils, and commercially available products can be easily obtained.
The addition amount of the antioxidant is preferably 0.01 to 10% by mass with respect to the total mass of the layer to be added.

As the plasticizer, those used as plasticizers for general resins such as dibutyl phthalate and dioctyl phthalate can be used as they are, and the amount used is about 0 to 30 parts by mass with respect to 100 parts by mass of the binder resin. Is appropriate.
Further, a leveling agent may be added to the photosensitive layer. Examples of the leveling agent include silicone oils such as dimethyl silicone oil and methylphenyl silicone oil; polymers having a perfluoroalkyl group in the chain or oligomers. As for the usage-amount of the said leveling agent, 0-1 mass part is preferable with respect to 100 mass parts of said binder resins.

  Next, the formation of the electrostatic latent image can be performed, for example, by uniformly charging the surface of the image carrier and then performing imagewise exposure, and by the electrostatic latent image forming unit. Can do. The electrostatic latent image forming means includes, for example, charging means for uniformly charging the surface of the image carrier (the charging device 3), and exposure means (laser) for exposing the surface of the image carrier imagewise. Exposure means such as light).

The charging can be performed, for example, by applying a voltage to the surface of the image carrier 1 using the charging device 3.
The charging device is not particularly limited and may be appropriately selected depending on the purpose. For example, the charging device known per se provided with a conductive or semiconductive roller, brush, film, rubber blade, etc. And non-contact chargers utilizing corona discharge such as corotrons and corotrons.
The charging device preferably has voltage applying means for applying a voltage having an AC component.

The exposure can be performed, for example, by exposing the surface of the image carrier imagewise using the exposure unit.
The exposure means is not particularly limited as long as the surface of the image carrier 1 charged by the charging device 3 can be exposed like an image to be formed, and may be appropriately selected according to the purpose. Examples thereof include various exposure apparatuses such as a copying optical system, a rod lens array system, a laser optical system, a liquid crystal shutter optical system, and an LED array optical system.
In the present invention, an optical back side system in which imagewise exposure is performed from the back side of the image carrier may be adopted.

<Development process and development means>
The developing step is a step of developing the electrostatic latent image using a toner or a developer to form a visible image.
The visible image can be formed, for example, by developing the electrostatic latent image using the toner or the developer, and can be performed by the developing unit.
The developing unit is not particularly limited as long as it can be developed using, for example, the toner or the developer, and can be appropriately selected from known ones. For example, the toner or developer is accommodated. A preferable example includes at least a developing device capable of applying the toner or the developer to the electrostatic latent image in a contact or non-contact manner.

-Toner-
The toner preferably has an average circularity of 0.93 to 1.00, which is an average value of the circularity SR represented by the following formula 1, and more preferably 0.95 to 0.99. This average circularity is an index of the degree of unevenness of toner particles, and indicates 1.00 when the toner is a perfect sphere, and the average circularity becomes smaller as the surface shape becomes more complicated.
<Formula 1>
Circularity SR = (perimeter of circle having the same area as the projected area of toner particles) / (perimeter of projected image of toner particles)

  When the average circularity is in the range of 0.93 to 1.00, the surface of the toner particles is smooth, and the toner particles and the contact area between the toner particles and the photosensitive member are small, so that the transferability is excellent. Further, since the toner particles have no corners, the developer agitation torque in the developing device is small, and the agitation drive is stabilized, so that no abnormal image is generated. In addition, since there are no angular toner particles in the toner that forms the dots, the pressure is uniformly applied to the entire toner that forms the dots when pressed against the recording medium during transfer, and the transfer is not easily lost. Further, since the toner particles are not angular, the abrasive power of the toner particles themselves is small, and the surface of the image carrier is not damaged or worn.

The circularity SR can be measured using, for example, a flow particle image analyzer (manufactured by Toa Medical Electronics Co., Ltd., FPIA-1000).
First, 0.1 to 0.5 ml of a surfactant (preferably alkylbenzene sulfonate) is added as a dispersant to 100 to 150 ml of water from which impure solids have been removed in advance. Add ~ 0.5g. The suspension in which the sample is dispersed is subjected to dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and the shape and particle size of the toner are measured by the above apparatus with the dispersion concentration being 3000 to 10000 / μl.

The toner has a mass average particle diameter (D4) of preferably 3 to 10 μm, and more preferably 4 to 8 μm. In this range, since the toner particles have a sufficiently small particle size with respect to the minute latent image dots, the dot reproducibility is excellent. When the mass average particle diameter (D4) is less than 3 μm, phenomena such as a decrease in transfer efficiency and a decrease in blade cleaning properties may occur. is there.
The toner has a mass average particle diameter (D4) to number average particle diameter (D1) ratio (D4 / D1) of preferably 1.00 to 1.40, and more preferably 1.00 to 1.30. The closer the ratio (D4 / D1) is to 1, the sharper the particle size distribution of the toner. In the range of (D4 / D1) from 1.00 to 1.40, selective development depending on the toner particle size. Since image quality does not occur, the image quality is excellent. In addition, since the toner particle size distribution is sharp, the triboelectric charge amount distribution is also sharp and the occurrence of fog is suppressed. Further, when the toner particle diameter is uniform, the latent image dots are developed so as to be arranged densely and orderly, so that the dot reproducibility is excellent.

Here, the mass average particle diameter (D4) and the particle size distribution of the toner are measured by, for example, a Coulter counter method. Examples of the measuring device for the particle size distribution of toner particles by the Coulter counter method include Coulter Counter TA-II and Coulter Multisizer II (both manufactured by Coulter).
First, 0.1 to 5 ml of a surfactant (preferably alkyl benzene sulfonate) is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution. Here, the electrolytic solution is a solution prepared by preparing a 1% NaCl aqueous solution using primary sodium chloride. For example, ISOTON-II (manufactured by Coulter) can be used. Here, 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and the measurement device is used to measure the volume and number of toner particles or toner using a 100 μm aperture as the aperture. Volume distribution and number distribution are calculated. From the obtained distribution, the mass average particle diameter (D4) and the number average particle diameter (D1) of the toner can be obtained.
As channels, 2.00 to less than 2.52 μm; 2.52 to less than 3.17 μm; 3.17 to less than 4.00 μm; 4.00 to less than 5.04 μm; 5.04 to less than 6.35 μm; 6 Less than 35 to 8.00 μm; less than 8.00 to less than 10.08 μm; less than 10.08 to less than 12.70 μm; less than 12.70 to less than 16.00 μm; less than 16.00 to less than 20.20 μm; Uses 13 channels of less than 40 μm; 25.40 to less than 32.00 μm; 32.00 to less than 40.30 μm, and targets particles having a particle size of 2.00 μm to less than 40.30 μm.

  As the toner having such a substantially spherical shape, a toner composition containing a polyester prepolymer having a functional group containing a nitrogen atom, a polyester, a colorant, and a release agent is crosslinked in the presence of resin fine particles in an aqueous medium. It can be prepared by an extension reaction. The toner manufactured by this reaction can reduce the hot offset by curing the surface of the toner, and it can be suppressed that the fixing device becomes dirty and appears on the image.

Examples of the prepolymer made of the modified polyester resin include a polyester prepolymer (A) having an isocyanate group, and examples of the compound that extends or crosslinks with the prepolymer include amines (B).
Examples of the polyester prepolymer (A) having an isocyanate group include a polycondensate of a polyol (1) and a polycarboxylic acid (2) and a polyester having an active hydrogen group, which is further reacted with a polyisocyanate (3). Is mentioned. Examples of active hydrogen groups possessed by the polyester include hydroxyl groups (alcoholic hydroxyl groups and phenolic hydroxyl groups), amino groups, carboxyl groups, mercapto groups, and the like. Among these, alcoholic hydroxyl groups are particularly preferable.

Examples of the polyol (1) include diol (1-1), trivalent or higher polyol (1-2), (1-1) alone or (1-1) and a small amount of (1-2). Mixtures are preferred.
Examples of the diol (1-1) include alkylene glycol (ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, etc.); alkylene ether glycol (Diethylene glycol, triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, etc.); Alicyclic diols (1,4-cyclohexanedimethanol, hydrogenated bisphenol A, etc.); Bisphenols (bisphenol A) Bisphenol F, bisphenol S, etc.); alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, etc.) adduct of the above alicyclic diol Alkylene oxide of the bisphenols (ethylene oxide, propylene oxide, butylene oxide, etc.), etc. adducts. Among these, alkylene glycols having 2 to 12 carbon atoms and alkylene oxide adducts of bisphenols are preferable, and combined use of alkylene oxide adducts of bisphenols and alkylene glycols having 2 to 12 carbon atoms is particularly preferable.

  Examples of the trivalent or higher polyol (1-2) include 3 to 8 or higher polyhydric aliphatic alcohols (glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, sorbitol, etc.); (Trisphenol PA, phenol novolak, cresol novolak, etc.); alkylene oxide adducts of the above trivalent or higher polyphenols.

Examples of the polycarboxylic acid (2) include dicarboxylic acid (2-1) and trivalent or higher polycarboxylic acid (2-2). Among these, (2-1) alone and (2-1) ) And a small amount of (2-2).
Examples of the dicarboxylic acid (2-1) include alkylene dicarboxylic acids (succinic acid, adipic acid, sebacic acid, etc.); alkenylene dicarboxylic acids (maleic acid, fumaric acid, etc.); aromatic dicarboxylic acids (phthalic acid, isophthalic acid, Terephthalic acid, naphthalenedicarboxylic acid, etc.). Among these, alkenylene dicarboxylic acid having 4 to 20 carbon atoms and aromatic dicarboxylic acid having 8 to 20 carbon atoms are particularly preferable.
Examples of the trivalent or higher polycarboxylic acid (2-2) include aromatic polycarboxylic acids having 9 to 20 carbon atoms (such as trimellitic acid and pyromellitic acid). In addition, as polycarboxylic acid (2), you may make it react with polyol (1) using the acid anhydride or lower alkyl ester (methyl ester, ethyl ester, isopropyl ester, etc.) of the above-mentioned thing.

  As for the ratio of the polyol (1) and the polycarboxylic acid (2), the equivalent ratio [OH] / [COOH] of the hydroxyl group [OH] and the carboxyl group [COOH] is preferably 2/1 to 1/1. 5/1 to 1/1 is more preferable, and 1.3 / 1 to 1.02 / 1 is still more preferable.

  Examples of the polyisocyanate (3) include aliphatic polyisocyanates (tetramethylene diisocyanate, hexamethylene diisocyanate, 2,6-diisocyanatomethylcaproate, etc.); alicyclic polyisocyanates (isophorone diisocyanate, cyclohexylmethane diisocyanate, etc.) Aromatic diisocyanates (tolylene diisocyanate, diphenylmethane diisocyanate, etc.); araliphatic diisocyanates (α, α, α ′, α′-tetramethylxylylene diisocyanate, etc.); isocyanurates; Those blocked with caprolactam, etc. These may be used individually by 1 type and may use 2 or more types together.

  As for the ratio of the polyisocyanate (3), the equivalent ratio [NCO] / [OH] of the isocyanate group [NCO] and the hydroxyl group [OH] of the polyester having a hydroxyl group is preferably 5/1 to 1/1. 1 to 1.2 / 1 is more preferable, and 2.5 / 1 to 1.5 / 1 is still more preferable. If the [NCO] / [OH] exceeds 5, the low-temperature fixability may be deteriorated. If the molar ratio of [NCO] is less than 1, the urea content in the modified polyester becomes low, and hot offset resistance Sex worsens.

  The content of the polyisocyanate (3) component in the prepolymer (A) having an isocyanate group at the terminal is preferably 0.5 to 40% by mass, more preferably 1 to 30% by mass, and 2 to 20% by mass. Is more preferable. When the content is less than 0.5% by mass, the hot offset resistance deteriorates, and it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability. When the content exceeds 40% by mass, low-temperature fixability is obtained. May get worse.

The number of isocyanate groups contained per molecule in the prepolymer (A) having the isocyanate group is preferably 1 or more on average, more preferably 1.5 to 3 on average, and 1.8 to 2.5 on average. Further preferred. When the number is less than 1 per molecule, the molecular weight of the urea-modified polyester is lowered, and the hot offset resistance may be deteriorated.

  As the amines (B), the diamine (B1), trivalent or higher polyamine (B2), amino alcohol (B3), amino mercaptan (B4), amino acid (B5), and amino groups of B1 to B5 were blocked. (B6) etc. are mentioned. Examples of the diamine (B1) include aromatic diamines (phenylenediamine, diethyltoluenediamine, 4,4′diaminodiphenylmethane, etc.); alicyclic diamines (4,4′-diamino-3,3′dimethyldicyclohexylmethane, diaminecyclohexane, Isophorone diamine etc.); and aliphatic diamines (ethylene diamine, tetramethylene diamine, hexamethylene diamine etc.) and the like. Examples of the trivalent or higher polyamine (B2) include diethylenetriamine and triethylenetetramine. Examples of amino alcohol (B3) include ethanolamine and hydroxyethylaniline. Examples of amino mercaptan (B4) include aminoethyl mercaptan and aminopropyl mercaptan. Examples of the amino acid (B5) include aminopropionic acid and aminocaproic acid. Examples of the B1-B5 amino group blocked (B6) include ketimine compounds and oxazoline compounds obtained from the B1-B5 amines and ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.). Among these amines (B), preferred are B1 and a mixture of B1 and a small amount of B2.

  Furthermore, if necessary, the molecular weight of the urea-modified polyester can be adjusted using an elongation terminator. Examples of the elongation terminator include monoamines (diethylamine, dibutylamine, butylamine, laurylamine, etc.), or those obtained by blocking them (ketimine compounds).

The ratio of the amines (B) is the equivalent ratio [NCO] / [NHx] of the isocyanate group [NCO] in the prepolymer (A) having an isocyanate group and the amino group [NHx] in the amine (B). Is preferably 1/2 to 2/1, more preferably 1.5 / 1 to 1 / 1.5, and still more preferably 1.2 / 1 to 1 / 1.2. If the [NCO] / [NHx] exceeds 2 or less than 1/2, the molecular weight of the urea-modified polyester (i) becomes low, and the hot offset resistance deteriorates.
In the present invention, the polyester (i) modified with a urea bond may contain a urethane bond together with a urea bond. The molar ratio between the urea bond content and the urethane bond content is preferably 100/0 to 10/90, more preferably 80/20 to 20/80, and still more preferably 60/40 to 30/70. When the molar ratio of the urea bond is less than 10%, the hot offset resistance may be deteriorated.

By these reactions, the modified polyester used in the toner, especially the urea-modified polyester (i) can be produced. These urea-modified polyesters (i) are produced by a one-shot method or a prepolymer method. The mass average molecular weight of the urea-modified polyester (i) is preferably 10,000 or more, more preferably 20,000 to 10,000,000, and still more preferably 30,000 to 1,000,000. When the mass average molecular weight is less than 10,000, the hot offset resistance may be deteriorated.
The number average molecular weight of the urea-modified polyester is not particularly limited when the unmodified polyester (ii) described later is used, and may be a number average molecular weight that can be easily obtained to obtain the mass average molecular weight. (I) When used alone, the number average molecular weight is preferably 20,000 or less, more preferably 1,000 to 10,000, and still more preferably 2,000 to 8,000. When the number average molecular weight exceeds 20,000, low temperature fixability and glossiness when used in a full color image forming apparatus may be deteriorated.

In the present invention, not only the polyester (i) modified with a urea bond but also the polyester (ii) not modified can be included as a binder resin component together with the (i). By using (ii) in combination, the low-temperature fixability and the gloss when used in a full-color apparatus are improved, so that it is preferable to use alone. Examples of (ii) include the same polycondensates of polyol (1) and polycarboxylic acid (2) as in the polyester component (i), and preferred ones are also the same as (i). Further, (ii) is not limited to unmodified polyester, but may be modified with a chemical bond other than a urea bond, for example, may be modified with a urethane bond. It is preferable that (i) and (ii) are at least partially compatible with each other in terms of low-temperature fixability and hot offset resistance.
Therefore, the polyester component (i) and (ii) preferably have similar compositions. When (ii) is contained, the mass ratio of (i) and (ii) is preferably 5/95 to 80/20, more preferably 5/95 to 30/70, and further preferably 5/95 to 25/75. 7/93 to 20/80 is particularly preferable. When the mass ratio of (i) is less than 5% by mass, the hot offset resistance may be deteriorated, and it may be disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability.

  The peak molecular weight of (ii) is preferably 1,000 to 30,000, more preferably 1,500 to 10,000, and still more preferably 2,000 to 8,000. When the peak molecular weight is less than 1,000, the heat resistant storage stability may be deteriorated, and when it exceeds 10,000, the low temperature fixability may be deteriorated. The hydroxyl value of (ii) is preferably 5 or more, more preferably 10 to 120, and still more preferably 20 to 80. If the hydroxyl value is less than 5, it may be disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability. 1-30 are preferable and, as for the acid value of said (ii), 5-20 are more preferable. By having an acid value, it tends to be negatively charged.

The glass transition temperature (Tg) of the binder resin is preferably 50 to 70 ° C, and more preferably 55 to 65 ° C. When the glass transition temperature is less than 50 ° C., blocking of the toner during high temperature storage may be deteriorated, and when it exceeds 70 ° C., the low temperature fixability becomes insufficient. Due to the coexistence of the urea-modified polyester resin, the toner used in the present invention tends to have good heat storage stability even when the glass transition point is low, as compared with known polyester-based toners.
As the storage elastic modulus of the binder resin, the temperature (TG ′) at which the measurement frequency is 20 Hz is 10,000 dyne / cm 2 is preferably 100 ° C. or more, and more preferably 110 to 200 ° C. When the temperature (TG ′) is less than 100 ° C., the hot offset resistance may be deteriorated.
As the viscosity of the binder resin, the temperature (Tη) at 1000 poise at a measurement frequency of 20 Hz is preferably 180 ° C. or less, and more preferably 90 to 160 ° C. When the temperature (Tη) exceeds 180 ° C., the low-temperature fixability deteriorates. That is, TG ′ is preferably higher than Tη from the viewpoint of achieving both low temperature fixability and hot offset resistance. In other words, the difference between TG ′ and Tη (TG′−Tη) is preferably 0 ° C. or higher, more preferably 10 ° C. or higher, and still more preferably 20 ° C. or higher. The upper limit of the difference is not particularly limited. Further, from the viewpoint of achieving both heat-resistant storage stability and low-temperature fixability, the difference between Tη and Tg is preferably 0 to 100 ° C, more preferably 10 to 90 ° C, and still more preferably 20 to 80 ° C.

The binder resin can be produced by the following method.
First, the polyol (1) and the polycarboxylic acid (2) are produced at 150 to 280 ° C. in the presence of a known esterification catalyst such as tetrabutoxytitanate or dibutyltin oxide, and reduced pressure as necessary. Water is distilled off to obtain a polyester having a hydroxyl group. Subsequently, this is made to react with polyisocyanate (3) at 40-140 degreeC, and the prepolymer (A) which has an isocyanate group is obtained. Further, (A) is reacted with amines (B) at 0 to 140 ° C. to obtain a polyester modified with a urea bond. When reacting (3) and reacting (A) and (B), a solvent may be used as necessary.
Usable solvents include, for example, aromatic solvents (toluene, xylene, etc.); ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.); esters (ethyl acetate, etc.); amides (dimethylformamide, dimethylacetamide, etc.), Inactive to isocyanate (3) such as ethers (tetrahydrofuran, etc.).
When using polyester (ii) not modified with urea bond, (ii) is produced in the same manner as polyester having a hydroxyl group, and this is dissolved in the solution after completion of the reaction of (i). , Mix.

Further, the toner used in the present invention can be produced by the following method, but is not limited thereto.
The toner may be formed by reacting a dispersion made of a prepolymer (A) having an isocyanate group in an aqueous medium with (B), or using a urea-modified polyester (i) produced in advance. Good. As a method for stably forming a dispersion comprising urea-modified polyester (i) or prepolymer (A) in an aqueous medium, a toner raw material comprising urea-modified polyester (i) or prepolymer (A) in an aqueous medium is used. And a method of dispersing by shearing force.
The prepolymer (A) and other toner compositions (hereinafter sometimes referred to as toner raw materials), colorants, colorant master batches, release agents, charge control agents, unmodified polyester resins, Mixing may be performed when the dispersion is formed in the medium, but it is more preferable to mix the toner raw materials in advance and then add and disperse the mixture in the aqueous medium. In the present invention, other toner raw materials such as a colorant, a release agent, and a charge control agent do not necessarily have to be mixed when forming particles in an aqueous medium. It may be added later. For example, after forming particles not containing a colorant, the colorant can be added by a known dyeing method.
As the aqueous medium, water alone may be used, but a solvent miscible with water may be used in combination. Examples of miscible solvents include alcohols (methanol, isopropanol, ethylene glycol, etc.), dimethylformamide, tetrahydrofuran, cellosolves (methyl cellosolve, etc.), lower ketones (acetone, methyl ethyl ketone, etc.), and the like.

  The amount of the aqueous medium used relative to 100 parts by mass of the toner composition containing the urea-modified polyester (i) and the prepolymer (A) is preferably 50 to 2000 parts by mass, and more preferably 100 to 1000 parts by mass. When the amount used is less than 50 parts by mass, the toner composition is not well dispersed, and toner particles having a predetermined particle size may not be obtained. When the amount used exceeds 2000 parts by mass, it is not economical.

Moreover, a dispersing agent can also be used as needed. It is preferable to use a dispersant because the particle size distribution becomes sharp and the dispersion is stable.
The dispersion method is not particularly limited and may be appropriately selected depending on the intended purpose. For example, known equipment such as a low-speed shear method, a high-speed shear method, a friction method, a high-pressure jet method, and an ultrasonic wave can be applied. . In order to make the particle diameter of the dispersion 2 to 20 μm, a high-speed shearing method is preferable. When a high-speed shearing disperser is used, the number of rotations is not particularly limited, but is preferably 1000 to 30000 rpm, more preferably 5000 to 20000 rpm. The dispersion time is not particularly limited, but in the case of a batch method, it is usually 0.1 to 5 minutes. As temperature at the time of dispersion | distribution, 0-150 degreeC is preferable normally and 40-98 degreeC is more preferable. Higher temperatures are preferred in that the dispersion made of urea-modified polyester (i) or prepolymer (A) has a low viscosity and is easy to disperse.

  In the step of synthesizing the urea-modified polyester (i) from the prepolymer (A), the amine (B) may be added and reacted before the toner composition is dispersed in the aqueous medium, or may be dispersed in the aqueous medium. An amine (B) may be added later to cause a reaction from the particle interface. In this case, urea-modified polyester is preferentially produced on the surface of the manufactured toner, and a concentration gradient can be provided inside the particles.

In the reaction, it is preferable to use a dispersant as necessary.
There is no restriction | limiting in particular as said dispersing agent, According to the objective, it can select suitably, For example, surfactant, a slightly water-soluble inorganic compound dispersing agent, a polymeric protective colloid, etc. are mentioned. These may be used individually by 1 type and may use 2 or more types together. Among these, surfactants are preferable.

Examples of the surfactant include an anionic surfactant, a cationic surfactant, a nonionic surfactant, and an amphoteric surfactant.
Examples of the anionic surfactant include alkylbenzene sulfonates, α-olefin sulfonates, phosphate esters, and the like. Among these, those having a fluoroalkyl group are preferable. Examples of the anionic surfactant having a fluoroalkyl group include a fluoroalkylcarboxylic acid having 2 to 10 carbon atoms or a metal salt thereof, disodium perfluorooctanesulfonylglutamate, 3- [omega-fluoroalkyl (6 carbon atoms). -11) Oxy] -1-alkyl (carbon number 3-4) sodium sulfonate, 3- [omega-fluoroalkanoyl (carbon number 6-8) -N-ethylamino] -1-propanesulfonic acid sodium, fluoroalkyl (Carbon number 11-20) carboxylic acid or its metal salt, perfluoroalkyl carboxylic acid (carbon number 7-13) or its metal salt, perfluoroalkyl (carbon number 4-12) sulfonic acid or its metal salt, perfluoro Octanesulfonic acid diethanolamide, N-propyl-N- (2-hydroxy Ethyl) perfluorooctanesulfonamide, perfluoroalkyl (carbon number 6-10) sulfonamidopropyltrimethylammonium salt, perfluoroalkyl (carbon number 6-10) -N-ethylsulfonylglycine salt, monoperfluoroalkyl (carbon number) 6-16) Ethyl phosphate and the like. Examples of commercially available surfactants having a fluoroalkyl group include Surflon S-111, S-112, S-113 (Asahi Glass Co., Ltd.); Fluorard FC-93, FC-95, FC-98, FC- 129 (manufactured by Sumitomo 3M); Unidyne DS-101, DS-102 (manufactured by Daikin Industries); Megafac F-110, F-120, F-113, F-191, F-812, F-833 (large) Nippon Ink Chemical Co., Ltd.); Xtop EF-102, 103, 104, 105, 112, 123A, 123B, 306A, 501, 201, 204 (manufactured by Tochem Products); Neos) and the like.

  Examples of the cationic surfactant include amine salt type surfactants and quaternary ammonium salt type cationic surfactants. Examples of the amine salt type surfactant include alkylamine salts, aminoalcohol fatty acid derivatives, polyamine fatty acid derivatives, imidazolines, and the like. Examples of the quaternary ammonium salt type cationic surfactant include alkyltrimethylammonium salt, dialkyldimethylammonium salt, alkyldimethylbenzylammonium salt, pyridinium salt, alkylisoquinolinium salt, benzethonium chloride and the like. . Among the cationic surfactants, aliphatic quaternary ammonium such as aliphatic primary, secondary or tertiary amine acids having a fluoroalkyl group, perfluoroalkyl (6 to 10 carbon atoms) sulfonamidopropyltrimethylammonium salt, etc. Salts, benzalkonium salts, benzethonium chloride, pyridinium salts, imidazolinium salts, and the like. Commercially available products of the cationic surfactant include, for example, Surflon S-121 (manufactured by Asahi Glass Co., Ltd.); Florard FC-135 (manufactured by Sumitomo 3M Co.); Unidyne DS-202 (manufactured by Daikin Industries Ltd.), MegaFuck F-150 F-824 (manufactured by Dainippon Ink & Chemicals, Inc.); Xtop EF-132 (manufactured by Tochem Products);

Examples of the nonionic surfactant include fatty acid amide derivatives and polyhydric alcohol derivatives.
Examples of the amphoteric surfactant include alanine, dodecyldi (aminoethyl) glycine, di (octylaminoethyl) glycine, N-alkyl-N, N-dimethylammonium betaine and the like.

Examples of the poorly water-soluble inorganic compound dispersant include tricalcium phosphate, calcium carbonate, titanium oxide, colloidal silica, and hydroxyapatite.
Examples of the polymeric protective colloid include acids, (meth) acrylic monomers containing a hydroxyl group, vinyl alcohol or ethers of vinyl alcohol, esters of vinyl alcohol and a compound containing a carboxyl group, amides Examples thereof include homopolymers or copolymers such as compounds or their methylol compounds, chlorides, those having a nitrogen atom or a heterocyclic ring thereof, polyoxyethylenes, and celluloses.
Examples of the acids include acrylic acid, methacrylic acid, α-cyanoacrylic acid, α-cyanomethacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid, maleic anhydride, and the like. Examples of the (meth) acrylic monomer containing a hydroxyl group include β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, β-hydroxypropyl acrylate, β-hydroxypropyl methacrylate, and γ-acrylate. -Hydroxypropyl, γ-hydroxypropyl methacrylate, 3-chloro-2-hydroxypropyl acrylate, 3-chloro-2-hydroxypropyl methacrylate, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, glycerol monoacrylate Glycerin monomethacrylate, N-methylol acrylamide, N-methylol methacrylamide and the like. Examples of the vinyl alcohol or ethers with vinyl alcohol include vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, and the like. Examples of the esters of vinyl alcohol and a compound containing a carboxyl group include vinyl acetate, vinyl propionate, and vinyl butyrate. Examples of the amide compound or these methylol compounds include acrylamide, methacrylamide, diacetone acrylamide acid, or these methylol compounds. Examples of the chlorides include acrylic acid chloride and methacrylic acid chloride. Examples of the homopolymer or copolymer such as those having a nitrogen atom or a heterocyclic ring thereof include vinyl pyridine, vinyl pyrrolidone, vinyl imidazole, and ethylene imine. Examples of the polyoxyethylene are polyoxyethylene, polyoxypropylene, polyoxyethylene alkylamine, polyoxypropylene alkylamine, polyoxyethylene alkylamide, polyoxypropylene alkylamide, polyoxyethylene nonylphenyl ether, polyoxyethylene Examples thereof include oxyethylene lauryl phenyl ether, polyoxyethylene stearyl phenyl ester, and polyoxyethylene nonyl phenyl ester. Examples of the celluloses include methyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose.

In the preparation of the dispersion, a dispersion stabilizer can be used as necessary. Examples of the dispersion stabilizer include acids that are soluble in acids and alkalis such as calcium phosphate salts.
When the dispersion stabilizer is used, the calcium phosphate salt can be removed from the fine particles by a method of dissolving the calcium phosphate salt with an acid such as hydrochloric acid, followed by washing with water or a method of decomposing with an enzyme.

  In the preparation of the dispersion, a catalyst for the extension reaction or the crosslinking reaction can be used. Examples of the catalyst include dibutyltin laurate and dioctyltin laurate.

Furthermore, in order to lower the viscosity of the toner composition, a solvent in which the urea-modified polyester (i) or the prepolymer (A) is soluble can be used. The use of a solvent is preferable in that the particle size distribution becomes sharp. The solvent is preferably volatile from the viewpoint of easy removal.
Examples of the solvent include toluene, xylene, benzene, carbon tetrachloride, methylene chloride, 1,2-dichloroethane, 1,1,2-trichloroethane, trichloroethylene, chloroform, monochlorobenzene, dichloroethylidene, methyl acetate, ethyl acetate, Examples thereof include methyl ethyl ketone and methyl isobutyl ketone. These may be used individually by 1 type and may use 2 or more types together. Among these, aromatic solvents such as toluene and xylene; halogenated hydrocarbons such as methylene chloride, 1,2-dichloroethane, chloroform and carbon tetrachloride are preferable, and aromatic solvents such as toluene and xylene are more preferable.
0-300 mass parts is preferable, as for the usage-amount of the solvent with respect to 100 mass parts of said prepolymers (A), 0-100 mass parts is more preferable, and 25-70 mass parts is still more preferable. When a solvent is used, it is removed by heating under normal pressure or reduced pressure after the elongation and / or crosslinking reaction.

  The elongation and / or crosslinking reaction time is selected depending on the reactivity of the isocyanate group structure of the prepolymer (A) and the amines (B), but is usually preferably 10 minutes to 40 hours, and preferably 2 to 24 hours. More preferred. The reaction temperature is preferably 0 to 150 ° C, more preferably 40 to 98 ° C. Furthermore, a known catalyst can be used as necessary. Specific examples include dibutyltin laurate and dioctyltin laurate.

  In order to remove the organic solvent from the obtained emulsified dispersion, a method in which the temperature of the entire system is gradually raised to completely evaporate and remove the organic solvent in the droplets can be employed. It is also possible to spray the emulsified dispersion in a dry atmosphere to completely remove the water-insoluble organic solvent in the droplets to form toner fine particles, and also remove the aqueous dispersant by evaporating it. is there. As a dry atmosphere in which the emulsified dispersion is sprayed, a gas obtained by heating air, nitrogen, carbon dioxide gas, combustion gas, or the like, in particular, various air currents heated to a temperature equal to or higher than the boiling point of the highest boiling solvent used is generally used. Sufficient quality can be obtained with a short treatment such as spray dryer, belt dryer or rotary kiln.

When the particle size distribution at the time of emulsification dispersion is wide and washing and drying processes are performed while maintaining the particle size distribution, the particle size distribution can be adjusted by classification into a desired particle size distribution.
In the classification operation, the fine particle portion can be removed in the liquid by a cyclone, a decanter, centrifugation, or the like. Although classification operation may be performed after obtaining as powder after drying, it is preferable in terms of efficiency to be performed in a liquid. The unnecessary fine particles or coarse particles obtained can be returned to the kneading step and used for the formation of particles. At that time, unnecessary fine particles or coarse particles may be wet.
The dispersant used is preferably removed from the obtained dispersion as much as possible, but it is preferable to carry out it simultaneously with the classification operation described above.

  By mixing the resulting dried toner powder with dissimilar particles such as release agent fine particles, charge control fine particles, fluidizing agent fine particles, and colorant fine particles, or by giving mechanical impact force to the mixed powder By immobilizing and fusing on the surface, it is possible to prevent detachment of the foreign particles from the surface of the resulting composite particle.

  As specific means, (1) a method of applying an impact force to the mixture by blades rotating at high speed, (2) the mixture is injected into a high-speed air stream, accelerated, and particles or composite particles are mixed with an appropriate collision plate. There is a method of making it collide. As equipment, Ong mill (manufactured by Hosokawa Micron Corporation), I-type mill (manufactured by Nippon Pneumatic Co., Ltd.), with reduced pulverization air pressure, hybridization system (manufactured by Nara Machinery Co., Ltd.), kryptron system ( Kawasaki Heavy Industries, Ltd.) and automatic mortar.

  As the colorant used in the toner, pigments and dyes conventionally used as toner colorants can be used. Specifically, carbon black, lamp black, iron black, ultramarine, nigrosine dye, Aniline blue, phthalocyanine blue, phthalocyanine green, Hansa yellow G, rhodamine 6C lake, calco oil blue, chrome yellow, quinacridone red, benzidine yellow, rose bengal and the like can be used alone or in combination.

  Further, if necessary, in order to give the toner particles magnetic properties, for example, iron oxides such as ferrite, magnetite and maghemite; metals such as iron, cobalt and nickel, or alloys of these with other metals, etc. The magnetic component may be contained alone or in combination in the toner particles. These components can also be used as a colorant component.

  Further, the number average particle diameter of the colorant in the toner used in the present invention is preferably 0.5 μm or less, more preferably 0.4 μm or less, and further preferably 0.3 μm or less. When the number average particle diameter exceeds 0.5 μm, the dispersibility of the pigment does not reach a sufficient level, and preferable transparency may not be obtained. On the other hand, the colorant having a fine particle diameter of less than 0.1 μm is sufficiently smaller than a half wavelength of visible light, and thus is considered not to adversely affect the light reflection and absorption characteristics. Therefore, the colorant particles having a number average particle size of less than 0.1 μm contribute to good color reproducibility and transparency of the OHP sheet having a fixed image. On the other hand, when there are many colorants having a particle size larger than 0.5 μm, the transmission of incident light is hindered or scattered, and the brightness of the projected image of the OHP sheet is reduced. There is a tendency to decrease the color. Further, when a large amount of colorant having a particle size larger than 0.5 μm is present, the colorant is detached from the surface of the toner particles, which may cause various problems such as fogging, drum contamination, and poor cleaning. The colorant having a particle size larger than 0.7 μm is preferably 10% by number or less, more preferably 5% by number or less of the total colorant.

Further, by mixing the colorant together with part or all of the binder resin in advance after adding a wetting liquid, the binder resin and the colorant are initially sufficiently attached, In the subsequent toner production process, the colorant is dispersed more effectively in the toner particles, the dispersed particle diameter of the colorant is reduced, and better transparency can be obtained.
As the binder resin used for kneading in advance, the resins exemplified as the binder resin for toner can be used as they are, but are not limited thereto.

  As a specific method for kneading the mixture of the binder resin and the colorant with the wetting liquid in advance, for example, the binder resin, the colorant and the wetting liquid are obtained after mixing with a blender such as a Henschel mixer. The obtained mixture is kneaded at a temperature lower than the melting temperature of the binder resin by a kneader such as a two-roll or three-roll to obtain a sample.

In addition, as the wetting liquid, a general one can be used in consideration of the solubility of the binder resin and the paintability with the colorant. It is preferable from the viewpoint of dispersibility. Among these, the use of water is particularly preferable from the viewpoint of environmental considerations and maintaining the dispersion stability of the colorant in the subsequent toner production process.
According to this manufacturing method, not only the particle diameter of the colorant particles contained in the obtained toner is reduced, but also the uniformity of the dispersion state of the particles is increased, so that the color reproducibility of the projected image by OHP is further improved. Get better.

The toner preferably contains a release agent together with the binder resin and the colorant.
The release agent is not particularly limited and may be appropriately selected from known ones according to the purpose. For example, polyolefin wax (polyethylene wax, polypropylene wax, etc.); long chain hydrocarbon (paraffin wax) And waxes containing carbonyl groups. Among these, a carbonyl group-containing wax is particularly preferable.
Examples of the carbonyl group-containing wax include polyalkanoic acid esters (carnauba wax, montan wax, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1 , 18-octadecanediol distearate, etc.); polyalkanol esters (tristearyl trimellitic acid, distearyl maleate, etc.); polyalkanoic acid amides (ethylenediamine dibehenyl amide, etc.); polyalkylamides (trimellitic acid tristearyl amide) Etc.); dialkyl ketones (distearyl ketone, etc.) and the like. Among these, polyalkanoic acid esters are particularly preferable.

40-160 degreeC is preferable, as for melting | fusing point of the said mold release agent, 50-120 degreeC is more preferable, and 60-90 degreeC is still more preferable. When the melting point is less than 40 ° C., the heat resistant storage stability may be adversely affected.
The melt viscosity of the release agent is preferably 5 to 1000 cps, more preferably 10 to 100 cps at a temperature 20 ° C. higher than the melting point. When the melt viscosity exceeds 1000 cps, the effect of improving hot offset resistance and low-temperature fixability may be poor.
The content of the release agent in the toner is preferably 0 to 40% by mass, and more preferably 3 to 30% by mass.

Further, in order to accelerate the toner charge amount and its rise, a charge control agent may be contained in the toner as necessary. Since a color change occurs when a colored material is used as the charge control agent, a colorless or nearly white material is preferable.
The charge control agent is not particularly limited and may be appropriately selected from known ones according to the purpose. For example, triphenylmethane dyes, molybdate chelate pigments, rhodamine dyes, alkoxy amines, Examples include quaternary ammonium salts (including fluorine-modified quaternary ammonium salts), alkylamides, phosphorus simple substances or compounds, tungsten simple substances or compounds, fluorine-based activators, salicylic acid metal salts, and metal salts of salicylic acid derivatives.
As the charge control agent, a commercially available product can be used. Examples of the commercially available product include quaternary ammonium salt Bontron P-51, oxynaphthoic acid metal complex E-82, and salicylic acid metal complex. E-84, E-89 of a phenol-based condensate (both manufactured by Orient Chemical Industries); TP-302, TP-415 of a quaternary ammonium salt molybdenum complex (both manufactured by Hodogaya Chemical Co., Ltd.); Quaternary ammonium salt copy charge PSY VP2038, triphenylmethane derivative copy blue PR, quaternary ammonium salt copy charge NEG VP2036, copy charge NX VP434 (both manufactured by Hoechst); LRA-901, boron complex LR-147 (all manufactured by Nippon Carlit Co., Ltd.), quinacridone, azo face , Sulfonate group, carboxyl group, and polymer compounds having a functional group such as a quaternary ammonium salt.

  The amount of the charge control agent added varies depending on the type of the binder resin, the presence / absence of the additive, the toner production method including the dispersion method, and the like, and cannot be uniquely defined, but with respect to 100 parts by mass of the binder resin. 0.1-10 mass parts is preferable and 0.2-5 mass parts is more preferable. When the addition amount exceeds 10 parts by mass, the chargeability of the toner is too high, the effect of the charge control agent is reduced, the electrostatic attraction force with the developing roller is increased, the flowability of the developer is reduced, and the image The concentration may decrease. These charge control agents can be melted and kneaded together with a masterbatch and resin and then dissolved and dispersed, or they can be added directly when dissolved and dispersed in an organic solvent, or fixed after the toner particles are prepared on the toner surface. You may let them.

Further, when the toner composition is dispersed in the aqueous medium during the toner production process, resin fine particles mainly for stabilizing the dispersion may be added.
The resin fine particles may be any resin as long as it can form an aqueous dispersion, and may be a thermoplastic resin or a thermosetting resin. For example, vinyl resins, polyurethane resins, epoxy resins, polyester resins , Polyamide resin, polyimide resin, silicon resin, phenol resin, melamine resin, urea resin, aniline resin, ionomer resin, polycarbonate resin and the like. These may be used individually by 1 type and may use 2 or more types together. Among these, a vinyl resin, a polyurethane resin, an epoxy resin, a polyester resin, or a combination thereof is preferable because an aqueous dispersion of fine spherical resin particles can be easily obtained.
As the vinyl resin, a polymer obtained by homopolymerization or copolymerization of a vinyl monomer is used. For example, a styrene- (meth) acrylic acid ester resin, a styrene-butadiene copolymer, a (meth) acrylic acid-acrylic acid ester. Examples thereof include a polymer, a styrene-acrylonitrile copolymer, a styrene-maleic anhydride copolymer, and a styrene- (meth) acrylic acid copolymer.

As an external additive for assisting the fluidity, developability and chargeability of the toner particles, inorganic fine particles are suitable.
Examples of the inorganic fine particles include silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, tin oxide, silica sand, clay, mica, wollastonite, and diatomaceous earth. , Chromium oxide, cerium oxide, pengala, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, silicon nitride and the like.
The primary particle diameter of the inorganic fine particles is preferably 5 nm to 2 μm, and more preferably 5 nm to 500 nm. The specific surface area of the inorganic fine particles by BET method is preferably 20 to 500 m <2> / g. The addition amount of the inorganic fine particles in the toner is preferably 0.01 to 5% by mass, and more preferably 0.01 to 2.0% by mass.

  Other polymer fine particles such as polystyrene, methacrylic acid ester and acrylic acid ester copolymer obtained by soap-free emulsion polymerization, suspension polymerization and dispersion polymerization, polycondensation system such as silicone, benzoguanamine and nylon, thermosetting resin And polymer particles.

  A fluidizing agent can also be added to the toner. The fluidizing agent performs surface treatment to increase hydrophobicity, and can prevent deterioration of flow characteristics and charging characteristics even under high humidity. Examples of the fluidizing agent include a silane coupling agent, a silylating agent, a silane coupling agent having a fluorinated alkyl group, an organic titanate coupling agent, an aluminum coupling agent, silicone oil, and modified silicone oil. Can be mentioned.

  Examples of the cleaning property improver for removing the developer after transfer remaining on the photosensitive member or the intermediate transfer member include fatty acid metal salts such as zinc stearate, calcium stearate and stearic acid; polymethyl methacrylate fine particles, polystyrene Examples thereof include polymer fine particles produced by soap-free emulsion polymerization of fine particles and the like. The polymer fine particles preferably have a relatively narrow particle size distribution and a volume average particle size of 0.01 to 1 μm.

  By using such a toner, as described above, it is possible to form a high-quality toner image having excellent development stability.

  Further, the image forming apparatus of the present invention can be applied not only to the combined use with the above-described polymerization method toner suitable for obtaining a high quality image, but also to an irregular shaped toner by a pulverization method, Even in this case, the life of the apparatus can be greatly extended. As a material constituting such a pulverized toner, those usually used as an electrophotographic toner can be applied without particular limitation.

  As the binder resin used in the pulverized toner, for example, styrene such as polystyrene, poly p-chlorostyrene, polyvinyltoluene, or the like, or a substituted polymer thereof; styrene / p-chlorostyrene copolymer, styrene / propylene Copolymer, styrene / vinyl toluene copolymer, styrene / vinyl naphthalene copolymer, styrene / methyl acrylate copolymer, styrene / ethyl acrylate copolymer, styrene / butyl acrylate copolymer, styrene / acrylic Octyl acid copolymer, styrene / methyl methacrylate copolymer, styrene / ethyl methacrylate copolymer, styrene / butyl methacrylate copolymer, styrene / α-chloromethyl methacrylate copolymer, styrene / acrylonitrile copolymer Styrene / vinyl methyl ketone copolymer, Styrene copolymers such as tylene / butadiene copolymers, styrene / isoprene copolymers, styrene / maleic acid copolymers; polymethyl acrylate, polybutyl acrylate, polymethyl methacrylate, polybutyl methacrylate, etc. Acrylic ester-based homopolymers or copolymers thereof; polyvinyl derivatives such as polyvinyl chloride and polyvinyl acetate; polyester-based polymers, polyurethane-based polymers, polyamide-based polymers, polyimide-based polymers, polyol-based polymers, Examples thereof include epoxy polymers, terpene polymers, aliphatic or alicyclic hydrocarbon resins, and aromatic petroleum resins. These may be used individually by 1 type and may use 2 or more types together. Among these, a styrene-acrylic copolymer resin, a polyester resin, and a polyol resin are preferable from the viewpoint of electrical characteristics, cost, and the like, and further, polyester resins and polyol resins are preferable as those having good fixing characteristics. Particularly preferred.

  In the pulverized toner, together with these resin components, the colorant component, wax component, charge control component and the like as described above are premixed as necessary, and then kneaded at a temperature close to the melting temperature of the resin component, and then cooled. Thereafter, a toner may be prepared through a pulverizing and classifying step, and the external additive component may be appropriately added and mixed as necessary.

  The developing device (developing device) may be of a dry developing type, a wet developing type, a single color developing unit, or a multicolor developing unit. For example, a toner having a stirrer that frictionally stirs and charges the toner or the developer, and a rotatable magnet roller is preferable.

In the developing device, for example, the toner and the carrier are mixed and stirred, and the toner is charged by friction at that time, and held on the surface of the rotating magnet roller in a raised state, thereby forming a magnetic brush . Since the magnet roller is disposed in the vicinity of the image carrier (photosensitive member), a part of the toner constituting the magnetic brush formed on the surface of the magnet roller is caused by the electric attractive force. It moves to the surface of the image carrier (photoreceptor). As a result, the electrostatic latent image is developed with the toner, and a visible image is formed with the toner on the surface of the image carrier (photoconductor).
The developer accommodated in the developing device is a developer containing the toner, but the developer may be a one-component developer or a two-component developer.

<Transfer process and transfer means>
The transfer step is a step of transferring the visible image to a recording medium directly or via an intermediate transfer member. After the primary transfer of the visible image onto the intermediate transfer member using the intermediate transfer member, the transfer step is performed. A mode in which a visible image is secondarily transferred onto the recording medium is preferable. A second or more, preferably full color toner is used as the toner, and a visible image is transferred onto an intermediate transfer member to form a composite transfer image. An embodiment including a primary transfer step and a secondary transfer step of transferring the composite transfer image onto a recording medium is more preferable.
The transfer can be performed, for example, by charging the image carrier (photosensitive member) with the transfer charger using the visible image, and can be performed by the transfer unit. The transfer means includes a primary transfer means for transferring a visible image onto an intermediate transfer member to form a composite transfer image, and a secondary transfer means for transferring the composite transfer image onto a recording medium. Embodiments are preferred.
The intermediate transfer member is not particularly limited and may be appropriately selected from known transfer members according to the purpose. For example, an intermediate transfer belt is preferably used.

  The image carrier is used when performing image formation by a so-called intermediate transfer method, in which a toner image formed on a photosensitive member is primarily transferred to perform color superposition, and further transferred to a recording medium. It may be a transfer body.

-Intermediate transfer member-
As the intermediate transfer member, a material exhibiting conductivity of a volume resistance of 1.0 × 10 ^{5 to} 1.0 × 10 ¹¹ Ω · cm is preferable. When the volume resistance is less than 1.0 × 10 ⁵ Ω · cm, so-called transfer dust is generated in which the toner image is disturbed due to discharge when the toner image is transferred from the photosensitive member to the intermediate transfer member. If it exceeds 1.0 × 10 ¹¹ Ω · cm, the counter charge of the toner image remains on the intermediate transfer member after the toner image is transferred from the intermediate transfer member to a recording medium such as paper. May appear as an afterimage on other images.

As the intermediate transfer member, for example, a metal oxide such as tin oxide or indium oxide, a conductive particle such as carbon black, or a conductive polymer, alone or in combination, kneaded with a thermoplastic resin, and then an extrusion molded belt A cylindrical or cylindrical plastic can be used. In addition to this, the above-mentioned conductive particles and conductive polymer are added to a resin solution containing a thermally crosslinkable monomer or oligomer, if necessary, and subjected to centrifugal molding while heating to obtain an intermediate transfer member on an endless belt. You can also.
When the surface layer is provided on the intermediate transfer member, among the surface layer materials used for the surface layer of the photoreceptor described above, the composition excluding the charge transport material is appropriately adjusted in combination with a conductive substance, Can be used.

The transfer unit (the primary transfer unit and the secondary transfer unit) includes at least a transfer unit that peels and charges the visible image formed on the image carrier (photoconductor) to the recording medium side. It is preferable to have. There may be one transfer means or two or more transfer means. Examples of the transfer device include a corona transfer device using corona discharge, a transfer belt, a transfer roller, a pressure transfer roller, and an adhesive transfer device.
The recording medium is not particularly limited, and can be appropriately selected from known recording media (standard recording paper, non-standard recording paper, cardboard, postcard, OHP sheet, etc.).

<Protective layer forming step and protective layer forming means>
The protective layer forming step is a step of forming a protective layer by applying the image carrier protective agent of the present invention to the surface of the image carrier after transfer.
As the protective layer forming means, the protective layer forming apparatus 2 of the present invention described above can be used.

<Fixing process and fixing means>
The fixing step is a step of fixing the visible image transferred to the recording medium using the fixing unit, and may be performed each time the toner of each color is transferred to the recording medium, or may be applied to the toner of each color. On the other hand, it may be carried out simultaneously at the same time in a state of being laminated.
The fixing unit is not particularly limited and may be appropriately selected depending on the intended purpose. However, a known heating / pressurizing unit is preferable. Examples of the heating / pressurizing means include a combination of a heating roller and a pressure roller, a combination of a heating roller, a pressure roller, and an endless belt.
The heating in the heating / pressurizing means is usually preferably 80 ° C to 200 ° C. As a heating method, various heating methods such as heater heating such as an electric heater, a halogen heater, and a carbon heater, electromagnetic induction heating using electromagnetic induction, and heating using a heating element such as a thermal head can be used.
In the present invention, for example, a known optical fixing device may be used together with or in place of the fixing step and the fixing unit depending on the purpose.

The neutralization step is a step of performing neutralization by applying a neutralization bias to the image carrier, and can be suitably performed by a neutralization unit.
The neutralization means is not particularly limited, and may be appropriately selected from known neutralizers as long as it can apply a neutralization bias to the image carrier. For example, a neutralization lamp or the like is preferable. It is done.

The cleaning step is a step of removing the electrophotographic toner remaining on the image carrier and can be suitably performed by a cleaning unit.
The cleaning unit is preferably provided downstream of the transfer unit in the moving direction (rotation direction) of the image carrier and upstream of the protective layer forming apparatus.
The cleaning means is not particularly limited, and may be selected from known cleaners as long as it can remove the electrophotographic toner remaining on the image carrier. For example, a magnetic brush cleaner, Suitable examples include electrostatic brush cleaners, magnetic roller cleaners, blade cleaners, brush cleaners, web cleaners, and the like.

The recycling step is a step of recycling the toner removed by the cleaning step to the developing unit, and can be suitably performed by the recycling unit.
The recycling means is not particularly limited, and known transport means (transport means using a coil, a screw, etc., means for transporting by mixing with air using a powder pump or an air pump, electrostatic transport means), etc. Can be mentioned.

The control means is a process for controlling the respective steps, and can be suitably performed by the control means.
The control means is not particularly limited as long as the movement of each means can be controlled, and can be appropriately selected according to the purpose. Examples thereof include devices such as a sequencer and a computer.

<Configuration example of image forming apparatus>
Here, FIG. 3 is a schematic sectional view showing an example of the image forming apparatus 100 including the protective layer forming apparatus of the present invention.
The image forming apparatus 100 includes an image forming apparatus main body (printer unit) 110 that performs image formation, a document reading unit (scanner unit) 120 installed on the upper part of the main unit 110, and an automatic document supply unit installed thereon. A paper device (ADF) 130 and a paper feed unit 200 installed at the lower part of the image forming apparatus main body 110 are provided, and have a function of a copying machine. The image forming apparatus 100 has a communication function with an external device, and can be used as a printer or a scanner by connecting to a personal computer or the like outside the device via a LAN. Further, it can be used as a facsimile by connecting to a telephone line or an optical line.

  In the image forming apparatus main body 110, four image forming units (image forming stations) 10 having the same configuration and different toner colors of the developing device 5 are arranged in parallel, and the four image forming units 10 have different toner colors. An image (for example, an image of yellow (Y), magenta (M), cyan (C), and black (K)) is formed, and a toner image of each color is superimposed on a transfer medium or an intermediate transfer medium and transferred to obtain multiple colors or A full color image can be formed. In the example of FIG. 3, the four image forming units 10 are juxtaposed along a belt-shaped transfer medium (hereinafter referred to as an intermediate transfer member) 7 stretched around a plurality of rollers. The toner images of the respective colors formed by the forming unit are sequentially transferred to the intermediate transfer member 7 in order, and then transferred to a sheet-like recording medium such as paper by the secondary transfer device 12.

  The image forming unit 10 for each color has the same configuration as that shown in FIG. 2, and a protective layer forming device 2, a charging device 3, a static device are formed around an image carrier (for example, a photosensitive drum) 1 (1Y, 1M, 1C, 1K). An exposure unit such as a laser beam from the electrostatic latent image forming device 8, a developing device 5, a primary transfer device 6, and a cleaning device 4 are arranged. Similarly to FIG. 2, the image forming unit 10 of each color includes a process cartridge 11 in which a protective layer forming device 2, a charging device 3, a developing device 5, and a cleaning device 4 are provided in a cartridge together with the photoreceptor 1. Used. The process cartridge 11 is detachably attached to the image forming apparatus main body 110.

Next, the operation of the image forming apparatus shown in FIG. 3 will be described. Here, a series of processes for image formation will be described using a negative-positive process. The operation of each image forming unit is the same.
Image carriers 1Y, 1M, 1C, and 1K typified by a photoreceptor (OPC) having an organic photoconductive layer are neutralized by a static elimination lamp (not shown) or the like, and uniformly negative by a charging device 3 having a charging member. Is charged.
When the image carrier is charged by the charging device, the image carrier 1Y, 1M, 1C, 1K is charged to a desired potential from a voltage application mechanism (not shown) to a charging member (for example, a charging roller). A voltage of an appropriate magnitude suitable for the above or a charging voltage obtained by superimposing an AC voltage thereon is applied.
The charged image carriers 1Y, 1M, 1C, and 1K form a latent image with laser light irradiated by an electrostatic latent image forming apparatus 8 including exposure means such as a laser optical system (the absolute value of the exposure portion potential is The potential becomes lower than the absolute value of the non-exposed portion potential).
Laser light is emitted from a semiconductor laser, and the surfaces of the image carriers 1Y, 1M, 1C, and 1K are moved along the rotation axis direction of the image carrier (main scanning direction) by a polygonal polygon mirror that rotates at high speed. Scan).
The latent image formed in this way is developed with a developer made of toner particles or a mixture of toner particles and carrier particles supplied on the developing sleeve of the developing roller 51 which is a developer carrying member in the developing device 5. As a result, a visible image of the toner is formed.
At the time of developing the latent image, a voltage of an appropriate magnitude or a voltage between the exposed portion and the non-exposed portion of the image carrier 1Y, 1M, 1C, 1K is applied to the developing sleeve from a voltage application mechanism (not shown). A developing bias superimposed with an AC voltage is applied.

The toner images formed on the image carriers 1Y, 1M, 1C, and 1K corresponding to the respective colors by the operation as described above are primarily transferred onto the intermediate transfer body 7 by the primary transfer device 6 in order. On the other hand, in synchronization with the image forming operation and the primary transfer operation, the paper feed roller 202 and the separation roller are selected from the paper feed cassettes selected from the multi-stage paper feed cassettes 201a, 201b, 201c, and 201d of the paper feed unit 200. A sheet-like recording medium such as paper is fed by a paper feeding mechanism 203, and is conveyed to a secondary transfer unit via conveying rollers 204, 205, 206 and registration rollers 207. In the secondary transfer portion, the toner image on the intermediate transfer member 7 is secondarily transferred to the conveyed recording medium by a secondary transfer device (for example, a secondary transfer roller) 12. In the above transfer step, it is preferable that a potential having a polarity opposite to the charging polarity of the toner is applied to the primary transfer device 6 and the secondary transfer device 12 as a transfer bias.
After the secondary transfer described above, the recording medium is separated from the intermediate transfer member 7 to obtain a transfer image. Further, the toner particles remaining on the photoreceptor 1 after the primary transfer are collected into the toner collection chamber in the cleaning device 4 by the cleaning member 41 of the cleaning device 4. Further, the toner particles remaining on the intermediate transfer member 7 after the secondary transfer are collected into the toner collecting chamber in the belt cleaning device 9 by the cleaning member of the belt cleaning device 9.

  An image forming apparatus 100 shown in FIG. 3 is a so-called tandem type intermediate transfer type image forming apparatus in which a plurality of the above-described image forming units 10 are arranged along the intermediate transfer body 7. A plurality of toner images with different colors sequentially formed on the respective photoreceptors 1Y, 1M, 1C, and 1K are once transferred onto the intermediate transfer body 7 and then transferred to a recording medium such as paper at once. To do. Then, the recording medium onto which the toner image has been transferred is sent to the fixing device 14 by the transport device 13 and the toner is fixed by heating, pressing, or the like. The recording medium after fixing is discharged to a discharge tray 17 by a transport device 15 and a discharge roller 16. The image forming apparatus 100 also has a double-sided printing function. During double-sided printing, the conveyance path downstream of the fixing device 14 is switched, and a recording medium on which a single-sided image is fixed is transferred through the double-sided conveyance apparatus 210. The paper is reversed, and is fed again to the secondary transfer unit by the transport roller 206 and the registration roller 207, and the image is transferred to the back side. The recording medium after transfer is conveyed to the fixing device 14 in the same manner as described above to fix the image, and the recording medium after fixing is discharged to a discharge tray 17.

  In the above configuration, the intermediate transfer member can be used without using an intermediate transfer member, and a tandem type direct transfer method image forming apparatus can be used. In the case of this direct transfer method, a recording medium is supported instead of the intermediate transfer member. Using a transfer belt or the like that transports, a plurality of toner images of different colors, which are sequentially created on each photoreceptor 1 (1Y, 1M, 1C, 1K) by each image forming unit 10, are directly transported by the transfer belt. Alternatively, the toner may be fixed to the recording medium after being sequentially transferred to the fixing device 14 by heating and pressurizing.

In the image forming apparatus as described above, the charging device 3 is preferably a charging device in which a charging member such as a charging roller is disposed in contact with or in close proximity to the surface of the image carrier. Compared with a so-called corotron or socorotron using a corona discharger, the amount of ozone generated during charging can be greatly suppressed.
However, in the charging device 3 that charges such a charging member in contact with or close to the surface of the image carrier, the discharge is performed in the region near the surface of the image carrier as described above. Tend to be stressful. However, by using the protective layer forming apparatus 2 using the protective agent 21 for the image carrier of the present invention, the image carrier 1 can be maintained for a long time without deteriorating. Image fluctuations due to the environment can be greatly suppressed, and stable image quality can be ensured.

  As described above, the image forming apparatus of the present invention has an excellent tolerance for fluctuations in the surface state of the image carrier, and has a configuration in which fluctuations in charging performance to the image carrier are highly suppressed. By using in combination with the toner having the structure, an extremely high quality image can be stably formed over a long period of time.

  EXAMPLES Specific examples of the present invention will be described below, but the present invention is not limited to these examples.

Example 1
-Production of protective agent 1 for image carrier-
Zinc stearate (number-based 50% particle size = 50 μm), boron nitride (number-based 50% particle size = 5 μm), and aluminum oxide fine particles (number-based 50% particle size = 0.5 μm) are shown in Table 1 below. In accordance with the mixing ratio (by weight).
The particle size distribution of each raw material was measured using a laser diffraction particle size distribution measuring device (SALD-2200, manufactured by Shimadzu Corporation), and the 50% diameter of the number distribution was defined as the particle size.
The raw materials were mixed using a wonder blender (WB-1, distributor: Osaka Chemical Co., Ltd.) at a rotational speed of 25000 rpm twice for 10 seconds to obtain a mixture powder of the sample.
The amount of the mixture introduced into the mold was calculated from the specific gravity, blending ratio and desired filling rate of each raw material measured in advance. In this example, the calculated amount (g) of the mixture of the protective agent formulation 1 was weighed, and a molded body of the protective agent for the image carrier was prepared by the following procedure.
Put the weighed composition of the protective agent formula 1 into an aluminum mold having a depth of 40 mm, a width of 8 mm, and a length of 350 mm, and after leveling the surface with a spatula, the height of the packing is 6 mm. The powder compacted body was molded by pressing with a pressing die.
The solid material of the protective agent formulation 1 was removed from the mold, shaped into 6 mm × 8 mm × 310 mm, and attached to a metal support to produce the protective agent 1 for an image carrier.

(Examples 2 to 23 and Comparative Examples 1 to 5)
-Preparation of image bearing member protective agents 2-27-
In Example 1, the protective materials 2 to 27 for the image carrier were prepared in the same manner as in Example 1 except that the raw material type, mixing ratio, and mixture input amount of the protective agent were as described in Table 1 below. Produced.
Further, the protective agent 28 was produced by melt molding using the same formulation as in Example 1.

<Measurement of protective agent properties>
The characteristics of the obtained image carrier protective agent were measured as follows.

The open cell rate and closed cell rate of the image carrier protective agent were measured by the following procedure.
1. Three rectangular parallelepipeds of about 5 cm × 6 mm × 8 mm are cut out from the protective agent for the image carrier.
2. Each of the image carrier protective agents cut out using calipers is measured, and an apparent volume V1 (cm ³ ) including voids is calculated.
3. The weight W1 (g) of the image carrier protective agent thus cut out is weighed.
4). A sample sample is pulverized, and a part thereof is precisely weighed to obtain W2 (g).
5. The crushed sample is put into a Beckman air comparison type hydrometer, and a volume V2 (cm ³ ) of the protective agent W2 (g) is obtained.
6). From each measured value, the porosity is calculated according to the following equation.
Porosity (%) = 100 × {V1−V2 · (W1 / W2)} / V1 (volume%)

A series of characteristic measurements were performed in a laboratory environment of about 20 ° C. and 50% RH.
The porosity of each image carrier protective agent is also shown in Table 1.

(Example 24)
2, the counter-type cleaning blade 41, the brush-like protective agent supplying member 22, and the trailing-type protective layer forming member 24 around the image carrier (photosensitive member) 1 following the transfer process. Were prepared in this order from the upstream side, and a process cartridge 11 having a protective layer forming apparatus 2 using the image carrier protective agent 1 of Example 1 was produced.
The obtained process cartridge is mounted on an image forming apparatus (color MFP image Neo Neo C600 manufactured by Ricoh Co., Ltd.) modified so that the process cartridge can be mounted, and an A4 size version, image area ratio = 100%, 50% A continuous image drawing test of up to 100,000 sheets was conducted using a manuscript containing 5 cm wide vertical belt-like images. Presence / absence of image abnormalities before and after the test in a normal temperature / humidity environment of 20 ° C. and 50% RH, a low temperature / low humidity environment of 10 ° C. and 25% RH, and a high temperature / high humidity environment of 35 ° C. and 80% RH. confirmed.
At this time, the toner was prepared by a polymerization method having a mass average particle diameter (D4) = 5.1 μm, a number average particle diameter (D1) = 4.3 μm, D4 / D1 = 1.19, and an average circularity = 0.98. The toner used was used.
As image abnormalities, streaky image defects, halftone image unevenness, and image blur related to the quality of cleaning performance were evaluated according to the following criteria.
The image was evaluated every 10,000 sheets, and when an abnormal image that could not be used was generated, the test was stopped at that time.

<Evaluation criteria for streak-like image defects>
◎: Extremely good ○: Practical problem level △: Practically acceptable level ×: Unusable

<Evaluation criteria for halftone image unevenness>
◎: Extremely good ○: Practical problem level △: Practically acceptable level ×: Unusable

<Evaluation criteria for image defects in blurred images>
◎: Extremely good ○: Practical problem level △: Practically acceptable level ×: Unusable

  Further, the consumption amount of the protective agent for the image carrier at the time of image evaluation was calculated as a difference from the initial weight. Furthermore, the uniformity of consumption was visually observed and evaluated according to the following criteria.

<Evaluation criteria for state of protective agent for image carrier>
○: Uniform consumption △: There is a slight difference between the belt part and the ground part (actual use level)
×: There is a clear difference between the band and the background (not practical)

  In addition, in order to evaluate the magnitude of the effect of deterioration of the image carrier, cleaning blade, and charging member on the image, the state of each member is observed at the initial stage and at the end of the evaluation to check for any abnormalities. The evaluation was based on the following criteria.

<Evaluation criteria for the state of each member>
○: Level equivalent to the initial level Δ: Slightly changed (Actual usable level)
×: Deteriorated

As a result, no deterioration was observed with each member as the number of printed sheets increased, and good image quality was obtained both after the initial output of 100,000 sheets, and no abnormality was observed in the image after the heat cycle. It has been found that the image forming apparatus of the present invention is useful in both image quality and lifetime.
The results of image quality evaluation and the consumption of the protective agent for the image carrier are shown in Tables 2 to 4 below, and the observation results of the member deterioration state are shown in Table 5 below.
The image forming apparatus of Example 1 was subjected to a paper passing test for a total of 500,000 sheets following the continuous image drawing test. No effect on the image was observed, and the image carrier, The cleaning member and the charging member were hardly deteriorated.

(Examples 25-46)
In Example 24, evaluation was performed in the same manner as in Example 24 except that the image carrier protecting agent 1 was changed to image carrier protecting agents 2 to 23.
The results of image quality evaluation and the consumption of the protective agent for the image carrier are shown in Tables 2 to 4 below, and the observation results of the member deterioration state are shown in Table 5 below.

(Comparative Examples 6 to 10)
In Example 24, evaluation was performed in the same manner as in Example 24 except that the image carrier protecting agents 24 to 28 were used instead of the image carrier protecting agent 1.
The results of image quality evaluation and the consumption of the protective agent for the image carrier are shown in Tables 2 to 4 below, and the observation results of the member deterioration state are shown in Table 5 below.
In addition, with respect to the protective agents 24 to 28, even if the pressing force to the protective agent supply member is adjusted and the supply amount of the image carrier protecting agent is adjusted, the protective agent is applied within a range where the image carrier is protected. Unevenness was not eliminated, and streak-like or strip-like image defects could not be eliminated.

(Example 47)
Following the transfer process, a protective layer forming member that also serves as a brush-type protective agent and a counter type cleaning blade is provided in this order around the image carrier from the upstream side. A process cartridge having a protective layer forming apparatus using Agent 1 was produced.
It is mounted on an image forming apparatus (color MFP image Neo Neo C455, manufactured by Ricoh Co., Ltd.) modified so that the above process cartridge can be mounted, and an A4 size version, image area ratio = 100%, 50% vertical belt image is 5 cm wide A continuous image drawing test was conducted on 100,000 originals entered in step 1, and the presence or absence of image abnormality before and after the test was confirmed.

At this time, the toner was prepared by a polymerization method having a mass average particle diameter (D4) = 5.1 μm, a number average particle diameter (D1) = 4.3 μm, D4 / D1 = 1.19, and an average circularity = 0.98. The toner used was used.
As image abnormalities, streak-like image defects, halftone image irregularities, and image blurs related to the quality of cleaning performance were evaluated in the same manner as in Example 24.
Further, in the same manner as in Example 24, in order to evaluate the magnitude of the influence of the deterioration of the image carrier, the cleaning blade, and the charging member on the image, the respective states at the initial and time points were observed, and whether there was any abnormality. It was confirmed.
Tables 3 to 4 below show the results of image quality evaluation and consumption of the protective agent for the image carrier, and Table 5 shows the observation results of the member deterioration state.

  From the results of Tables 1 to 5, Examples 24 to 47 using the image carrier protecting agent of the present invention have better image quality such as streaks, image unevenness, and image blur compared to Comparative Examples 6 to 10. In addition, it is recognized that the deterioration of the image carrier, the cleaning member, and the charging member due to the increase in the number of printed sheets is extremely small. Further, it can be seen that the consumption of the protective agent for the image carrier is carried out stably.

Example 31 (protective agent 1) is different from Example 24 (protective agent 8), Example 32 (protective agent 9), and Example 33 (protective agent). 10), as compared with Example 34 (protective agent 11) and Example 35 (protective agent 12) not containing fine particles, the image carrying is increased as the particle size of the fine particles contained in the protective agent for image carrier increases. The performance as a protective agent for an image carrier gradually decreased in that the surface of the body tends to be mechanically damaged. When the average particle size of the fine particles exceeds 1.5 μm, the removability of the protective agent layer becomes too high, and a decrease in performance is recognized in terms of image quality due to removal of undegraded protective agent. It was.
On the other hand, the particle size of the fine particles contained in the protective agent for the image carrier is too small, or when the fine particles are not contained, it is easy to accumulate electrical damage on the surface of the image carrier. The performance as a protective agent gradually decreased. When the average particle size of the fine particles is small, the removal of the protective agent layer is insufficient, and the removal of the deteriorated protective agent may be insufficient, and a slight decrease in performance is recognized in terms of image quality. Further, when the fine particles were not included, the uniformity of the protective agent layer was ensured, but the period during which the influence on each member had not occurred was slightly shortened.

  Example 36 (protective agent 13), Example 37 (protective agent 14), Example 38 (protective agent 15) differing in the content of fatty acid metal salt and solid lubricant as compared with Example 24 (Protective agent 1) In Example 39 (protective agent 16), when the respective content ratios were lower than the lower limit, the influence on the image carrier and the cleaning blade began to appear, and the image quality slightly decreased.

  Example 24 (protective agent 1) to Example 26 (protective agent 3) and the same material composition ratio and porosity, and adjusted so that the particle diameters of the fatty acid metal salt and the solid lubricant were different. When comparing Example 40 (protective agent 17) to Example 46 (protective agent 23), there is an effective range in which the image quality can be maintained for a long period of time for each particle size, and the ratio (Db / Da) It was confirmed that the uniformity of the protective agent consumption tends to be lost when the image quality is too large, and the performance tends to deteriorate slightly in terms of image quality.

  Example 25 (protective agent 1) is different from Example 24 (protective agent 2), Example 26 (protective agent 3), and Example in that the particle diameter of the fatty acid metal salt and the porosity of the protective agent molded product for image carrier are different. From comparison with 27 (protective agent 4) and Example 28 (protective agent 5), it was confirmed that the supply ability of the protective agent for the image carrier can be stabilized by controlling these.

On the other hand, Comparative Example 7, Comparative Example 8, Comparative Example 9, and Comparative Example using protective agent 25, protective agent 26, protective agent 27, and protective agent 28 that do not satisfy the requirements of the present invention as protective agents for image carriers. In all cases, in the supply of the protective agent for the image carrier, local deviations and fluctuations with time occurred, the image carrier was not sufficiently protected for a long time, and the image quality was long. It was not stably maintained for a period.
Further, in Comparative Example 6 (protective agent 24) using a melt-molded product as the protective agent for the image carrier, the protective agent has extremely high hardness, and the amount of protective agent supplied onto the image carrier is clearly insufficient. As a result, a portion where the protective agent is present sparsely occurs on the image carrier, and an equivalent protective effect and lubricating effect cannot be expressed, and image quality cannot be maintained over a long period of time.

  The protective agent and protective layer forming apparatus of the present invention described above protects the image carrier from electrical stress due to charging or the like and mechanical stress due to sliding of the cleaning member, and stabilizes the protective agent. Therefore, it can be suitably used for an electrophotographic process cartridge, an image forming apparatus, an image forming method, and the like.

It is a schematic principal part block diagram which shows the principal part structural example of the image forming part provided with the protective layer forming apparatus of this invention. It is a schematic sectional drawing for demonstrating the outline of the structural example of the process cartridge using the protective layer forming apparatus of this invention. It is a schematic block diagram which shows the structural example of the image forming apparatus which comprises the protective layer forming apparatus of this invention.

Explanation of symbols

1 (1Y, 1M, 1C, 1K): image carrier (photosensitive drum)
2: Protection layer forming device 3: Charging device (charging means)
4: Cleaning device (cleaning means)
5: Developing device (developing means)
6: Primary transfer device (transfer means)
7: Intermediate transfer member (or transfer medium)
8: Electrostatic latent image forming device 9: Belt cleaning device 10: Image forming unit 11: Process cartridge 12: Secondary transfer device 13: Conveying device 14: Fixing device 15: Conveying device 16: Paper ejection roller 17: Paper ejection tray 21: Protective agent for image carrier 22: Protective agent supply member 22a: Brush-like member (brush)
22b: support 23: pressing force applying member 24: protective layer forming member 24a: blade-like member 24b: pressing member 25: protective agent support member 41: cleaning member (cleaning blade)
42: cleaning pressing member 51: developing roller 52, 53: stirring and conveying screw 100: image forming apparatus 110: image forming apparatus main body (printer unit)
120: Document reading unit (scanner unit)
130: Automatic document feeder (ADF)
200: paper feed unit 201a to 201d: paper feed cassette 202: paper feed roller 203: separation roller 204, 205, 206: transport roller 207: registration roller 210: transport device for both sides L: exposure

Claims (11)

A protective layer forming apparatus for supplying a compacted image carrier protective agent to an image carrier by scraping with a protective agent supply member having a brush, and at least fatty acid metal salt powder as the image carrier protective agent In a protective layer forming apparatus using a compacted mixed powder containing a solid lubricant powder and
The number-based 50% particle diameter Da of zinc stearate as the fatty acid metal salt powder is 20 to 90 μm , and the number-based 50% particle diameter Db of boron nitride as the solid lubricant powder is 0.1. ～14Myuemu, the ratio of the particle diameters Da and Db, is Db / Da, 0 <Db / Da ≦ 0.4, the porosity of the image bearing member protective agent, 3 to 15% by volume, and the image bearing The protective layer forming apparatus , wherein the weight ratio of zinc stearate and boron nitride contained in the body protecting agent is 70/30 to 95/5 . The protective layer forming apparatus according to claim 1,
The protective layer forming apparatus, wherein the protective agent for an image carrier contains abrasive fine particles having a 50% particle diameter Dc of 0.1 to 1.5 μm on a number basis. In the protective layer formation apparatus of Claim 1 or 2,
An apparatus for forming a protective layer , comprising: a pressing force applying member that presses and contacts the protective agent for the image carrier to the protective agent supply member . In the protective layer formation apparatus of Claim 3 ,
Protection layer forming apparatus you further comprising a protective layer forming member which forms a protective layer of the image bearing member for protecting agent supplied to the surface of the image bearing member and a thin layer. A process cartridge comprising at least an image carrier and a protective layer forming apparatus according to claim 3, wherein the process cartridge is detachable from a main body of the image forming apparatus . The process cartridge according to claim 5 ,
A process cartridge comprising: cleaning means for removing toner remaining on the surface of the image carrier upstream of the protective layer forming apparatus in the moving direction of the image carrier . An image forming apparatus comprising the process cartridge according to claim 5 or 6 in an image forming unit . An image bearing member; an electrostatic latent image forming unit that forms an electrostatic latent image on the image bearing member; a developing unit that develops the electrostatic latent image with toner to form a visible image; Transfer means for transferring a visible image directly or via an intermediate transfer body, a protective layer forming apparatus according to claim 3 or 4, and fixing means for fixing the transferred image transferred to the recording medium. an image forming apparatus, comprising at least a. The image forming apparatus according to claim 8.
An image forming apparatus comprising: a cleaning unit that removes toner remaining on the surface of the image carrier on the downstream side of the transfer unit in the moving direction of the image carrier and on the upstream side of the protective layer forming apparatus. apparatus. The image forming apparatus according to claim 8 or 9, wherein
An image forming apparatus, wherein the electrostatic latent image forming unit includes a charging unit disposed in contact with or close to the surface of the image carrier . An electrostatic latent image forming step for forming an electrostatic latent image on an image carrier, a developing step for developing the electrostatic latent image with toner to form a visible image, and the visible image on a recording medium 3. A transfer step of transferring directly or via an intermediate transfer body, and protection for forming a protective layer on the surface of the image carrier after transfer using the protective layer forming apparatus according to claim 1 An image forming method comprising at least a layer forming step and a fixing step of fixing a transfer image transferred onto the recording medium .

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