JP4442896B2 - Non-magnetic one-component developer - Google Patents

Description

  The present invention relates to a non-magnetic one-component developer for forming an image by electrophotographic technology.

In recent years, there has been an increasing need for small color printers at low cost in office environments. The key technology in such products is how cheap the components can be made, and as a recent trend in machine configuration, the number of models that adopt the following methods a to c is increasing. Yes.
a. Simple and inexpensive one-component development method b. The charging means for the latent image holding body is a contact charging roller system that is inexpensive and advantageous for the environment. C. The cleaning mechanism is a blade cleaning system and no pressure adjustment mechanism (fixed system)

Most of them have a cartridge configuration in which each process or a combination thereof is detachable from the viewpoint of improving user operability and handling.
On the other hand, competition for higher image quality of printers is intensifying, and each company has adopted a spherical or substantially spherical polymer toner having a small particle size, a uniform particle size distribution, and good transferability.
However, the process machine configuration as described above due to low cost requirements and the flow of adopting polymerized toner due to high image quality requirements have the problems described in (1) to (3) below.

(1) Charging roller contamination in contact charging method (2) Deterioration of cleaning property of wet granulation method (spherical) toner in low-cost cleaning mechanism (3) Deterioration of charging property in non-magnetic one-component development method (of urethane-modified Pes toner (Charge improvement)

  Various efforts have been made to deal with the above problems, but more recently, in order to reduce the cost, there is an increasing number of configurations that do not have a mechanism for adjusting the linear pressure between the photosensitive member and the cleaning blade. The cleaning blade support portion is required to be fixed to the support portion completely by means of screws, adhesives, welding, etc., so that the cleaning performance can be maintained until the machine life.

  As a method for this purpose, a method has been proposed in which cleaning properties are improved by using metal oxide particles such as silica having a polarity opposite to the charged polarity of the toner as an external additive (see Patent Documents 1 to 6). .

In particular, large-sized inorganic particles are an essential component for cleaning near-spherical toner such as polymerized toner, and the cleaning performance can be maintained by the function of blocking large-sized inorganic particles at the photoreceptor and blade nip. It is considered (see Patent Document 7).
As this large-diameter inorganic particle, if it is limited to the cleaning property, it is considered that the function of forming a stationary layer by an amorphous particle of 100 nm or more is effective. For example, titania or titanate of 200 nm or more is preferably used.

However, on the other hand, since these particles have a low electric resistance, there is a drawback that when the particles adhere to and accumulate on the contact charging roller, the electric resistance of the charging roller is lowered and the charging performance as the charging roller cannot be maintained. Therefore, in the prior art, improvement of cleaning properties and suppression of contamination of the contact charging roller are contradictory problems.
In addition, for toner compositions containing urethane-modified polyester resins, the chargeability as a negatively charged toner caused by the urethane portion, which is generally positively charged, is cited as a problem, and CCA has been conventionally included or negatively charged. The chargeability is compensated by coating with high-hydrophobic fine particle silica.

  However, in general, in the one-component developing system, the toner and the charging member have a very simple configuration of the developing roller and the regulating blade, so that sufficient chargeability can be imparted to the urethane-modified polyester-containing toner only by the above means. As a result, it causes image noise such as dirt.

The subject in the thing of the said patent documents 1-7 is put together below.
Patent Document 1 describes that the cleaning property of the polymerized toner is improved by adding cerium oxide or strontium titanate particles having a BET specific surface area of 0.5 to 10 m ² / g, but these external additives are used. In such a case, the external additive detached from the toner moves and accumulates on the contact charging roller, and there is a drawback that noise due to poor charging of the photosensitive member is likely to occur.

  Patent Document 2 describes that filming is improved by using one of two types of silica particles having a polarity opposite to that of the toner, but the silica particles used in the present invention have a small particle size. This is insufficient to improve the cleaning property of the polymerized toner.

  Patent Documents 3 and 4 show characteristics such as filming and chargeability in an image forming method of a one-component development method by using an external additive having a specific BET specific surface area as particles that are charged with a polarity opposite to that of the toner. Although there is a description that it is improved, such an external additive is certainly effective in improving charging property and filming, but it cannot be improved in the cleaning property of a spherical toner such as a polymerized toner. There are drawbacks.

  Patent Document 5 describes that the addition of abrasive particles having a volume average diameter of 0.3 to 2 μm opposite to the toner to a spherical toner such as a polymerized toner improves the cleaning properties. When used, the external additive detached from the toner moves and accumulates on the contact charging roller, and there is a drawback that noise due to poor charging of the photosensitive member is likely to occur.

Patent Document 6 describes that the chargeability as a one-component developer is improved by adding magnesium, zinc, zirconium, or a strontium-based inorganic compound as an external additive that is charged with a polarity opposite to that of the toner. However, when these external additives are used, there is a drawback that the external additive detached from the toner moves and accumulates on the contact charging roller, and noise due to poor charging on the photosensitive member is likely to occur.

  Patent Document 7 describes that as a spherical toner external additive, monodispersed silica having a relatively large particle diameter of 80 to 300 nm is used to exert a damming effect on the cleaning blade portion. Since the silica particles have a monodispersed uniform particle size distribution and the silica particles themselves have a high fluidity, the rolling property at the blade portion is too good, so that the anti-damping effect is insufficient.

Japanese Patent Laid-Open No. 9-190008 JP-A-10-186708 JP 2002-6632 A JP 2002-287413 A JP 2002-318467 A JP 2003-207935 A JP 2004-53717 A

  An object of the present invention is to provide a developer and an image forming method that solve the above-described problems.

  As a result of intensive studies by the present inventors, silica particles obtained by a specific production method having a large particle diameter are effective for the problems (1) and (2). On the other hand, the present invention was completed by obtaining the knowledge that it is extremely effective when the silica particles having a large particle diameter are subjected to a specific surface treatment.

That is, the present invention has a configuration as described below.
(1) a charging process for charging a latent image holding member for holding an electrostatic latent image by contacting a charging roller;
An electrostatic latent image forming step of forming an electrostatic latent image on a primary charged latent image holding member;
A developing step by a one-component developing method in which the electrostatic latent image is developed with a developer of each color included in a plurality of developing devices, and a developer image is formed on the electrostatic latent image holding member;
A transfer step of transferring each color developer image formed on the latent image carrier to a recording material;
A blade cleaning step for removing residual toner particles on the latent image holding member after the transfer step by a fixed blade without having a movable part and a pressure adjusting mechanism, and a developer image transferred to the recording material A developer used in an image forming method comprising a fixing step for fixing to a recording material,
The developer includes a negatively charged colored particle composed of at least a binder resin and a colorant and at least two or more types of silica particles having different average particle diameters as external additives on the surface of the colored particle. It is a magnetic one-component developer, and among the silica particles, the silica particle having the larger particle diameter (external additive A) is at least surface-treated fused silica obtained from the raw material via SiO gas. The specific surface area is in the range of 10 to 40 m ² / g, contains 5% or more of particles of 100 nm or more, and the bulk density is 0.1 to 0.3 g. A non-magnetic one-component developer having a specific surface area of 100 m ² / g or more, wherein the smaller silica particles (external additive B) are in the range of / cm ³ .

(2) The nonmagnetic one-component developer according to (1) , wherein the silica particles (external additive A) are surface- treated with an amino group-containing silane coupling agent.
(3) The non-magnetic one-component developer according to (1) , wherein the colored particles are wet granulated toner particles mainly comprising a polyester resin obtained by a wet manufacturing method.
(4) As an external additive other than external additive A, hydrophobic silica (external additive B) having a number average particle diameter of primary particles of 10 nm or less and a specific surface area by a BET method of 100 m ² / g or more is used. It contains at least a hydrophobic inorganic oxide (external additive C) having a number average particle diameter of 10 to 35 nm and a specific surface area by a BET method of 50 to 100 m ² / g (1) A non-magnetic one-component developer described in 1.
(5) The nonmagnetic one-component developer according to (1) , wherein a part of the polyester resin of the colored particles is an oilless full-color toner composed of at least urethane-modified polyester.

(6) A toner composition comprising at least a resin and a colorant in which the colored particles are dissolved or dispersed in an organic solvent, and the dissolved or dispersed material is dispersed in an aqueous medium in the presence of an inorganic dispersant or fine particle polymer. The non-magnetic one-component development according to any one of claims 1 to 5, which is obtained by removing a solvent from an emulsified dispersion obtained by polyaddition reaction of the dissolved product or dispersion. Agent.
(7) An isocyanate group-containing prepolymer in which the colored particles are dispersed in a water-based medium in the presence of an inorganic dispersant or a fine particle polymer in which a toner composition made of a polyester resin is dispersed in the water-based medium. The nonmagnetic one-component developer according to claim 6, which is obtained by subjecting an elongation reaction and a crosslinking reaction with amines to remove the solvent of the obtained emulsified dispersion.

(8) a charging step for charging the latent image holding member for holding the electrostatic latent image by contacting a charging roller;
An electrostatic latent image forming step of forming an electrostatic latent image on a primary charged latent image holding member;
A developing step by a one-component developing method in which the electrostatic latent image is developed with a developer of each color included in a plurality of developing devices, and a developer image is formed on the electrostatic latent image holding member;
A transfer step of transferring each color developer image formed on the latent image carrier to a recording material;
A blade cleaning step for removing residual toner particles on the latent image holding member after the transfer step by a fixed blade without having a movable part and a pressure adjusting mechanism, and a developer image transferred to the recording material An image forming method comprising the fixing step of fixing to a recording material, wherein the one-component developer according to claim 1 is used as the developer.
(9) The image forming method according to (8), wherein the developing step applies an alternating electric field when developing the latent image on the image carrier.
(10) A process cartridge that integrally supports the latent image carrier and at least one means selected from the charging means, the developing means, and the cleaning means, and is detachable from the image forming apparatus main body. The image forming method according to claim 8, wherein the image forming method is configured.
11. The image forming method according to claim 10, wherein the fixing means for the toner image to the recording material is a heat roll type fixing device and does not have an oil application mechanism for imparting releasability. .

  By using the non-magnetic one-component developer of the present invention, charging roller contamination can be reduced, and the cleaning property in the blade cleaning system can be improved.

The colored particles in the one-component developer of the present invention (hereinafter, the developer is also referred to as toner) preferably have the following configuration.
First, the colored particles are spherical or substantially spherical colored particles having a volume average particle diameter of 3 to 7 μm, more preferably 4 to 6 μm, obtained by a wet granulation method as a configuration capable of achieving high image quality. Is preferred. When the volume average particle size is smaller than 3 μm, the handling property is remarkably deteriorated, and when it is larger than 7 μm, the image quality is deteriorated.
A specific numerical range of a spherical shape or a substantially spherical shape is 0.960 to 0.990 in terms of an average circularity measured by FPIA 2100.

  Examples of the wet granulation method include known production methods. For example, an emulsion polymerization aggregation method, a suspension polymerization method, a dissolution suspension method, or a method (SPR method) described in JP-A-2002-287400 can be used. It is.

In addition, as a binder resin for colored particles capable of achieving sufficient fixing strength with low energy, a polyester resin is generally preferably used, and a polymer for suppressing high temperature offset is generally used to cope with oilless fixing. Although it can add suitably, in that case, the polymeric body which extended | stretched chain length the polyester prepolymer with urethane can be used conveniently.
As a means for obtaining a wet process toner with such a material structure, among the above processes, the method described in JP-A-2002-287400 is particularly suitable.

Further, in the developer of the present invention, at least two kinds of silica particles having different particle diameters are used as external additives. As such silica particles, at least an external additive having a larger particle diameter (hereinafter also referred to as “external additive A”) has a charging property opposite to that of the toner, and contains 5% or more of particles of 100 nm or more. Silica particles having a specific surface area of 10 to 40 m ² / g in the BET method are used. More preferably, the external additive A is a large particle size silica obtained by a melting method, which is produced via a SiO gas state.

Further, as external additive B, the number average particle diameter of primary particles is 10 nm or less, hydrophobic silica having a specific surface area of 100 m ² / g or more by BET method, and as the second type of external additive C, the number average of primary particles is It comprises a hydrophobic inorganic oxide having a particle diameter of 10 to 35 nm and a specific surface area of 50 to 100 m ² / g by BET method.

The reason why such a configuration is preferable is as follows.
The external additive A is preferably obtained by subjecting silica particles produced by a melting method via a SiO gas state to a hydrophobic surface treatment, such as pyrolytic fumed silica by a conventional gas phase method, It has been found that the properties are significantly different from the sol-gel silica obtained by the wet method.

The fused silica used in the present invention is different from that obtained in a general fused silica production process, and has a BET specific surface area of 10 to 40 m ² / g and a bulk density of 0.1 to 0.3 g / cm ^3. “The silica particles produced by the melting method” are obtained as ultrafine powders.
(The bulk density is calculated from the bulk volume of silica at the time of stationary storage, and is calculated from the volume after standing for 10 minutes after charging the specified amount into the graduated cylinder)

  In other words, general fused silica is obtained by pulverizing natural silica raw materials such as silica and flame-melting at a high temperature of about 2000 ° C., while its particle size becomes large particles of several μm or more, The fused silica of the present invention is obtained by heat-treating a mixed raw material composed of finely pulverized silica silica, a reducing agent such as metal silicon powder and carbon powder, and water for forming a slurry at a high temperature in a reducing atmosphere. A major feature is that it is obtained by generating a gas and quickly cooling it in an atmosphere containing oxygen, and its particle size is submicron or less.

Since the particles thus obtained do not form a chain structure and have a relatively broad particle size distribution, there are many particles of 100 to 300 nm compared to conventionally known vapor phase fumed silica. Although the specific surface area is small, the bulk density is very low, and thus it is easy to contribute to the formation of a blocking layer during cleaning.
In addition, this silica generally has low adhesion to a charging roller coated with rubber or resin, and if it adheres, the material itself has high resistance, which causes image noise due to contamination of the charging roller. It has the feature of being difficult.

  Further, in order to obtain a damming effect at the time of cleaning, it is necessary to continuously supply the photosensitive member and the cleaning blade nip portion. In particular, the external additive A is subjected to a positive polarity surface treatment. preferable. This is because, when added to a negatively charged toner base (colored particles), it is convenient because it electrostatically adheres to the toner, and when the toner is developed on the photoreceptor, the external additive A is non-imaged on the photoreceptor by the developing electric field. This is because it is easy to form a damming layer at the time of cleaning effectively.

Further, since the positive charge is taken away from the toner when the external additive A is peeled off from the toner at the time of development, the negative charging performance of the toner is further enhanced as a secondary effect. At this time, silica particles having a specific surface area of less than 10 m ² / g are easily released from the toner, so that the effect of increasing the negative chargeability of the toner is only initial and is not preferable in view of durability. Further, silica particles larger than 40 m ² / g are not preferable because they are difficult to be separated from the toner, that is, the negative chargeability as the toner is adversely deteriorated.

  In addition, when the developer contains particles that are charged with the opposite polarity to the colored particles, the presence of “particles charged with the opposite polarity” from the components of the particles remaining on the surface of the electrostatic latent image carrier before and after development. Can be confirmed. “Particles charged in reverse polarity” are generally difficult to be transferred onto a transfer material by a transfer bias. This is because the charging characteristics of developers and general hydrophobic silica are in the same polarity charged state, whereas “particles with opposite polarity” are different in behavior during transfer from developers and hydrophobic silica. , It tends to remain on the electrostatic latent image carrier. Therefore, by comparing the amount of the external additive in the developer and the amount of the external additive remaining on the electrostatic latent image bearing member after the transfer, the second external additive can be expressed as “reverse polarity with respect to the colored particles. It can be determined whether the particle is a “charged particle”.

  Further, since the external additive A, which is “particles charged in reverse polarity”, is easily developed in the background portion, not in the image portion at the time of development, by performing white paper development without the image portion, The external additive A can be selectively developed and collected by the cleaning blade portion.

The “specific surface area and bulk density of silica particles existing free from colored particles” as defined in the present invention is measured for the silica particles recovered by the above method.
In fact, when the image forming method described in the present application was used to output an image of a hydrophobic silica fine particle having the same polarity as the toner and a developer obtained by externally adding a silica particle that is charged with a reverse polarity to the toner, The presence of “particles charged with opposite polarity to the colored particles” can be confirmed from the components of the particles remaining on the front and back surfaces of the electrostatic latent image carrier, and two or more types of external additives contained in the developer can be confirmed. It was found that the polarity relationship of the agent particles can be verified.

A production example of silica particles used in the present invention will be described.
Although the kind of raw material silica powder used by this invention is not specifically limited, From the cost surface, the silica powder obtained by grind | pulverizing a silica is preferable. The particle size is preferably from submicron to 100 μm, and particularly preferably from 1 to 30 μm, because of the reaction mechanism of the production method of the present invention via SiO gas. If it deviates from this range, it becomes difficult for coarse particles to be gasified to SiO at the heat treatment temperature in the present invention. Further, in the case of fine particles, not only the handleability is deteriorated, but also the particles are aggregated to cause the same obstacle to SiO gasification. The purity is preferably as high as possible.

In the present invention, there is a great feature in using a mixed raw material in which both a reducing agent composed of metal silicon powder and / or carbon powder and water are mixed with silica powder, and only one of them is sufficient for SiO gasification. In addition, silica powder of ultrafine powder (silica powder having BET specific surface area and bulk density described in paragraph [0030] above) cannot be produced. Here, “ultrafine powder” is defined as a powder having submicron particles or less as a main particle group and a specific surface area of 20 m ² / g or more.

  As in the present invention, when both the reducing agent and water are used, even if the heat treatment is below the boiling point of silica, surprisingly ultrafine powder (silica having BET specific surface area and bulk density described in the paragraph [0030] above) The reason why the powder is obtained is not clear, but probably due to the synergistic action of the reducing agent and water, the bond between the Si and O atoms on the silica particle surface is first weakened by water vapor and then the reducing agent acts. This is thought to be due to the remarkable acceleration of gasification to SiO. In addition, the presence of water not only increases the specific surface area but also acts to suppress the residual of the reducing agent.

As the reducing agent used in the present invention, metal silicon powder and / or carbon powder is used. The higher the purity, the better. Among these, metallic silicon is preferable from the viewpoint of promoting the gasification of SiO by reaction heat. Although the amount of the reducing agent depends on the reaction temperature and cannot be limited, it is generally 0.25 to 1.5 mol with respect to 1 mol of SiO _{2 in the} silica powder raw material.
The amount of water should not be too great, but may be any amount that provides a water content of at least 5% by weight in the mixture of the siliceous raw material powder and the reducing agent. Further, up to about 30% by weight of water may be replaced with alcohol such as ethanol.

  The form of the mixed raw material used in the present invention may be a slurry or a powder. In the case of a slurry, it becomes easy to inject the droplets from the nozzle to the flame, and the productivity can be further improved. In this case, the slurry concentration is preferably about 20 to 60% by weight. If it is less than 20% by weight, the productivity is lowered and the amount of heat of evaporation of water is increased, thereby inhibiting gasification to SiO. On the other hand, if it exceeds 60% by weight, it becomes difficult to inject into the flame in the form of droplets, and also gasification to SiO is hindered. As a method for injecting the slurry, a two-fluid nozzle capable of minimizing the droplet diameter as much as possible is preferable, and in particular, a structure having a structure capable of miniaturizing the droplet diameter to several μm is preferable.

  In the present invention, the mixed raw material is subjected to a heat treatment at a high temperature under a reducing atmosphere to generate a SiO-containing gas. The temperature of the heat treatment is preferably 1700 ° C. or higher, particularly preferably 1800 to 2100 ° C. When the heat treatment temperature is extremely low, the gasification reaction to SiO becomes insufficient. Although there is no restriction | limiting in particular in the upper limit of heat processing temperature, When the boiling point (2230 degreeC) of a silica is exceeded, the above-mentioned problem will arise, and 2230 degreeC or less is preferable.

  The high-temperature field of the heat treatment in the present invention can be formed in an electric furnace, a combustion furnace using a flame, etc., but the combustion furnace is used for mass production, easy adjustment of atmosphere, easy provision of local temperature distribution, etc. desirable. As the fuel gas, hydrogen, LPG, natural gas, acetylene gas, propane gas, butane, or the like is used, and as the auxiliary gas, air or oxygen is used.

  In the present invention, the high temperature field of the heat treatment needs to be maintained in a reducing atmosphere in order to promote gasification of the silica powder into SiO. In the case of an electric furnace, it is performed by supplying a reducing gas into a furnace such as hydrogen, hydrocarbon, carbon monoxide or the like, and in the case of a combustion furnace, it is performed by controlling the ratio of the fuel gas to the auxiliary combustion gas. More specifically, the auxiliary combustion gas is supplied in an amount of about 10 to 70% less than the theoretical value. Care should be taken because carbon will remain in the product if it is in an extremely reduced state.

  In the case of using an electric furnace, the supply of the mixed raw material is preferably continuously supplied to a furnace maintained in a high temperature field in the same direction as the flow of the reducing gas or in the opposite direction. In the case of a combustion furnace, it is injected into a flame in a reducing atmosphere. The spraying is performed using a spray atomizer such as a two-fluid nozzle, an ultrasonic atomizer, a rotating disk atomizer, or the like. The two-fluid nozzle is optimal in terms of mass productivity and promotion of gasification to SiO.

  In the case of injection by a two-fluid nozzle, the mixed raw material is desirably supplied as a slurry. In addition, the nozzle structure is preferably one in which droplets formed by slurry spraying are minute and difficult to block. For example, the diameter of the slurry spray tip opening is 2 mm or more, and the slurry spray gas at the tip of the nozzle The gas velocity is preferably 10 m / second or more, particularly preferably 100 to 400 m / second.

  Since the mixed raw material is heat-treated as described above to generate a SiO-containing gas, in the present invention, it is quickly discharged from a high temperature field and cooled in an atmosphere containing oxygen. When the electric furnace is used to discharge the SiO-containing gas, it is mixed with the reducing gas to be exhausted, but can also be actively sucked. In the case of a combustion furnace, it is carried out by positively aspirating as in the case of transporting a melt to a collection system in a normal melting furnace.

Next, the SiO-containing gas is oxidized in an atmosphere containing oxygen, and SiO becomes silica fine particles and is collected. In either case of an electric furnace or a combustion furnace, this operation is preferably performed by transporting the SiO-containing gas with a gas containing oxygen such as air to a collection system such as a bag filter. In this case, the average particle diameter and specific surface area can be adjusted by the gas introduction position and flow rate. In particular, in the case of using a combustion furnace, the SiO-containing gas that has passed through the flame is still at a high temperature of about 1600 ° C or higher, so a gas containing oxygen is supplied from a portion slightly away from the end of the flame and forced cooling is performed. It is preferable to make it.
As described above, the silica mother particles of the external additive A of the present invention can be obtained.

Further, in order to further obtain the above-described cleaning property improvement effect and charging property improvement effect, the external additive A is surface-treated so as to have a charging property opposite to that of the toner base particles.
When the toner is a negatively chargeable particle, the surface treatment agent of the external additive A that is charged with a polarity opposite to that of the toner is preferably a positive surface treatment such as a general positive surface treatment agent such as aminosilane / alumina dope.
A particularly preferred configuration is a combination treatment with an amino group-containing silane coupling agent (such as aminopropylethoxysilane) and silicone oil or HMDS.

Next, the external additive B will be described.
Hydrophobic silica having a number average particle size of 10 nm or less used as the external additive B is mainly mentioned as an essential component for imparting toner fluidity. Further, from the viewpoint of imparting fluidity and imparting toner charge, it is preferable that the particles are fixed so as to be covered with the toner and not easily separated.
When the particle size is larger than 10 nm, the fluidity imparting effect is small, which is not preferable. Further, as the external additive B, a hydrophobizing treatment is essential, but it is desirable that the external additive B be treated with a known surface treating agent.
Examples of the surface treatment agent include a general silane coupling agent. Examples thereof include silane coupling agents having the same polarity as the toner such as HMDS and dichlorodimethylsilane.

  Hydrophobic inorganic oxide having a primary particle number average particle size of 10 to 35 nm used as external additive C is added mainly for the purpose of reducing the cohesiveness between the particles of the toner. Greatly improves powder handling and transferability in a container or process cartridge.

When the number average particle diameter of the particles of the external additive C is smaller than 10 nm, the fluidity imparting effect is enhanced, but the powder cohesiveness improving effect is decreased, which is not preferable. On the other hand, when it is larger than 35 nm, a large amount of addition is required to exhibit the effect of improving the powder cohesiveness, and other side effects such as photoconductor noise occur.
Examples of the material preferably used as the external additive C include known inorganic oxide particles. In particular, silica, alumina, and titania particles are preferably used. Similarly to the external additive A, a hydrophobic surface is used. What has been treated is preferred.

  The image forming method in this patent preferably has the following configuration. These are all low-cost and simple configurations, and in such a machine configuration, they are configuration examples that improve the completeness of a low-cost and high-quality full-color printer.

<Development part>
The non-magnetic one-component development method is advantageous and preferable for commercialization of a low-cost and small color printer. In addition, a contact developing method / non-contact AC developing method can be selected as appropriate in the relationship between the developing roller and the photosensitive member, and the developing unit and the peripheral portion of the photosensitive member have an integrated cartridge configuration that is easy for the user to handle. Is possible.
<Peripheral area>
As the configuration of the peripheral portion of the photoconductor, an OPC photoconductor can be preferably used as the photoconductor, and a simple fixed blade cleaning method that does not have a constant pressure pressurization mechanism such as a spring is preferable for cost reduction. As the charging method, a contact charging roller method is preferable.
<Transfer>
A known intermediate transfer system can be used, and an intermediate transfer belt configuration is suitable.
<Fixing>
As the fixing mechanism, an oilless full-color fixing device configuration (belt fixing / roller fixing) that does not have an oil application mechanism is preferable for cost reduction.
As described above, a known configuration example can be used for each configuration.
In the following, it is assumed that at least such a low-cost process configuration is based on the combination of the developing unit in the contact one-component developing method and the peripheral part of the photosensitive member in combination with the OPC photosensitive member, the contact charging roller method, and the fixed cleaning blade method. An example is given.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples.
<Silica particle production equipment>
Ultra-fine silica was produced using a combustion furnace. The combustion furnace is provided with a double-pipe LPG-oxygen mixed burner at the top of the furnace so that an inner flame and an outer flame can be formed, and a two-fluid nozzle for slurry injection at the center of the burner. Is attached. Then, slurry is injected into the flame from the center of the two-fluid nozzle and oxygen is injected from the periphery thereof. The formation of the flame is performed by injecting a mixed gas of LPG-oxygen for forming the outer flame and the inner flame from the pores of the respective injection ports of the double tube structure burner, and the amount of LPG and oxygen gas These temperatures and atmospheres are adjusted by controlling. The part where the flame is formed is a reaction part, and contact with the air layer is cut off by the formation of the flame. Further, the side wall of the reaction part is protected by an alumina heat insulating material, and an air introduction hole is provided near the end of the reaction part, so that the generated gas can be rapidly oxidized. The product is sent to a collection system by a blower and collected by a bug filter.

100 weight of mixed powder consisting of 1.0 mol of metal silicon powder (number average particle size 10 μm, maximum particle size 100 μm) with respect to 1.0 mol of SiO _{2 of} silica powder (number average particle size 2 μm, maximum particle size 60 μm) A portion having a slurry concentration of 50% was prepared. This was injected from the center of a two-fluid nozzle (“Model No. BNH160S-IS” manufactured by Atmax Co., Ltd.) into the flame of the combustion furnace at a rate of 20 kg / h. For the injection, oxygen gas having a gage pressure of 0.3 MPa and a gas amount of about 12 Nm ³ / h was used.

On the other hand, from the burner, for the internal flame, a mixed gas of LPG: 6 Nm ³ / h and oxygen gas: 12 Nm ³ / h (corresponding to 40% of the complete combustion amount) is covered with the reducing flame and the injection portion of the slurry is covered with the reducing flame Injecting a mixture gas of LPG: 4 Nm ³ / h and oxygen gas: 16 Nm ³ / h (equivalent to 80% of the complete combustion amount) from the outermost peripheral space of the burner for external flame Shut off inner flame and external air layer. Moreover, the air supply amount from the air introduction hole is appropriately adjusted within a range of 100 to 400 Nm ³ / h.

About the collected powder, the specific surface area, the coarse particle ratio of 1 μm or more by particle size distribution measurement, and the purity of SiO ₂ were measured. The temperature of the inner flame part covering the injection part was measured at the center of the flame with a W-Re thermocouple. Furthermore, the determination of the reducing property of the internal flame part was judged by the oxygen concentration, and it was confirmed that the oxygen concentration was always 1 wt% or less.

<Manufacture of external additive A>
(1) In the above production conditions, the supply amount of LPG and oxygen gas in the inner periphery of the burner and the air supply amount from the air introduction hole were changed to various conditions, and silica particles (A- 1P to A-4P) were produced.
(2) Conventional production method The positive polarity particles of silica shown in Table 2 were produced.
(3) The particles shown in Table 3 were produced as large-diameter particles other than silica.

<Manufacture of toner base particles (colored particles)>
According to a general production example of an SPR toner, four colors of toner base particles having the following characteristics were produced.
Toner volume average particle diameter: 6.0 μm (Coulter Multisizer III)
Average circularity: 0.974 (FPIA2100)

<Toner particles: external additive formulation and conditions>
Four color toners were externally added according to the external additive formulation shown in Table 4. Further, as the external additives B and C, the following were used.
External additive B: TG811F (manufactured by Cabot; number average particle diameter 7 nm, HMDS treatment BET specific surface area 220 m ² / g)
External additive C: NX-90 (manufactured by Nippon Aerosil Co., Ltd .; number average particle size 18 nm, HMDS treatment BET specific surface area 74 m ² / g)
At this time, the manufacturing apparatus is a Henschel mixer FM20C / I manufactured by Mitsui Mining Co., Ltd., and the conditions are upper blade A0 / lower blade ST. Agents B and C were added for 5 minutes, and then external additive A was added and mixed for 2 minutes for external addition.

<Toner evaluation>
The following evaluation was performed using CX-3000 manufactured by Ricoh.
And the result determined about the following evaluation items is shown in Table 5.

[Evaluation item]
(Charging ground stain) Ground stain after printing 5% original 1000 sheets ○ Almost none
△ Slightly soiled (acceptable level)
× Terrible

(Charging roller dirt) Charging roller dirt after printing 5% original 1000 sheets ○ Almost no dirt
△ Dirt but no problem in practical use
× Stained image noise

(Transferability) Magenta / Cyan two-color superimposed character image after printing 5% original 1000 sheets
Evaluation of transfer defects (missing) ○ Almost no missing
△ Slightly missing
× Terrible

(Cleaning property) Cleaning of the photosensitive member after printing 5% original 1000 sheets
Check if left unwiped ○ Almost left unwiped
△ Slightly left unwiped (not generated on image)
× Uncleaned image noise generated

(Characteristics of recovered silica in photoconductor cleaning section)
The specific surface area and bulk density of the silica collected in the cleaning section on the photoconductor after printing 1,000 blank originals were measured. (The bulk density is measured with a 10 ml graduated cylinder of 0.5 g of silica)
In any evaluation, particularly good ones were judged as ◎.

  The non-magnetic one-component developer of the present invention forms a developer image on an electrostatic latent image carrier and then transfers the image onto a transfer material to form an image. It can be suitably used as a developer used for recording and electrostatic printing.

Claims (11)

A charging step for charging by charging a charging roller against a latent image holding body for holding an electrostatic latent image;
An electrostatic latent image forming step of forming an electrostatic latent image on a primary charged latent image holding member;
A developing step by a one-component developing method in which the electrostatic latent image is developed with a developer of each color included in a plurality of developing devices, and a developer image is formed on the electrostatic latent image holding member;
A transfer step of transferring each color developer image formed on the latent image carrier to a recording material;
A blade cleaning step for removing residual toner particles on the latent image holding member after the transfer step by a fixed blade without having a movable part and a pressure adjusting mechanism, and a developer image transferred to the recording material A developer used in an image forming method comprising a fixing step for fixing to a recording material,
In the developer, negatively charged colored particles comprising at least a binder resin and a colorant, and at least two or more types of silica particles having different average particle diameters as external additives are externally added to the surface of the colored particles. It is a non-magnetic one-component developer, and among the silica particles, the larger silica particle (external additive A) at least surface-treats the fused silica obtained from the raw material via SiO gas. The specific surface area is in the range of 10 to 40 m ² / g , particles containing 100 nm or more are contained in an amount of 5% or more, and the bulk density is 0.1 to 0.3. A non-magnetic one-component developer having a specific surface area of 100 m ² / g or more in a range of ³ g / cm ³ and having a smaller silica particle (external additive B). The nonmagnetic one-component developer according to claim 1, wherein the silica particles (external additive A) are surface- treated with an amino group-containing silane coupling agent.   The non-magnetic one-component developer according to claim 1, wherein the colored particles are wet granulated toner particles whose main component is a polyester resin obtained by a wet manufacturing method. As external additives other than external additive A, hydrophobic silica (external additive B) having a number average particle diameter of primary particles of 10 nm or less and a specific surface area by the BET method of 100 m ² / g or more and the number of primary particles It contains at least a hydrophobic inorganic oxide (external additive C) having an average particle diameter of 10 to 35 nm and a specific surface area by a BET method of 50 to 100 m ² / g. Nonmagnetic one-component developer.   2. The non-magnetic one-component developer according to claim 1, wherein a part of the polyester resin of the colored particles is an oilless full-color toner composed of at least a urethane-modified polyester.   A toner composition comprising at least a resin and a colorant is dissolved or dispersed in an organic solvent, and the solution or dispersion is dispersed in an aqueous medium in the presence of an inorganic dispersant or a fine particle polymer. The nonmagnetic one-component developer according to any one of claims 1 to 5, which is obtained by removing a solvent from an emulsified dispersion obtained by polyaddition reaction of a product or dispersion.   The colored particles are dispersed in a toner composition comprising a polyester resin in the aqueous medium, and an isocyanate group-containing prepolymer dispersed in an aqueous medium in the presence of an inorganic dispersant or fine particle polymer is added with amines. The nonmagnetic one-component developer according to claim 6, which is obtained by subjecting an elongation reaction and a crosslinking reaction to removal of the solvent of the obtained emulsified dispersion. A charging step for charging by charging a charging roller against a latent image holding body for holding an electrostatic latent image;
An electrostatic latent image forming step of forming an electrostatic latent image on a primary charged latent image holding member;
A developing step by a one-component developing method in which the electrostatic latent image is developed with a developer of each color included in a plurality of developing devices, and a developer image is formed on the electrostatic latent image holding member;
A transfer step of transferring each color developer image formed on the latent image carrier to a recording material;
A blade cleaning step for removing residual toner particles on the latent image holding member after the transfer step by a fixed blade without having a movable part and a pressure adjusting mechanism, and a developer image transferred to the recording material An image forming method comprising the fixing step of fixing to a recording material, wherein the one-component developer according to claim 1 is used as the developer.   The image forming method according to claim 8, wherein an alternating electric field is applied when the developing step develops the latent image on the image carrier.   The latent image carrier and at least one means selected from the charging means, the developing means, and the cleaning means are integrally supported and configured as a process cartridge that is detachable from the main body of the image forming apparatus. The image forming method according to claim 8, wherein the image forming method is an image forming method.   11. The image forming method according to claim 10, wherein the fixing means for fixing the toner image to the recording material is a heat roll type fixing device, and does not have an oil application mechanism for imparting releasability.