JP2005181569A - Image forming apparatus and image formation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus using an intermediate transfer member with which a good color electrophotographic image is obtained, and to provide an image forming method. <P>SOLUTION: The image forming apparatus is provided with a plurality of image forming units each comprising at least an electrophotographic photoreceptor, a charging device, an exposure device, a developing device, a transfer device and a cleaning device. Color toner images formed on the electrophotographic photoreceptors by using differently colored toners in the plurality of image forming units are sequentially superposed and transferred onto the intermediate transfer member to form a color toner image, this color toner image is retransferred at a time onto a recording material and the retransferred color toner image is fixed to form a color image. The amount of a residual monomer in each of the colored toners used in the developing devices of the plurality of image forming units is ≤300 ppm. The image forming apparatus has a cleaning device for the intermediate transfer member for removing residual toner after transfer remaining on the intermediate transfer member with a plurality of cleaning blades. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus used as a color copying machine or a color printer, and an image forming method using the image forming apparatus.

  In recent years, color copying machines and color printers have a strong tendency to obtain color images. The color image forming methods with high practical value are roughly classified into commonly used names. There are an intermediate transfer method, a KNC method (a method in which a multi-color superimposed image is formed on a photoconductor and transferred collectively), a tandem method, and the like. .

  Of course, since these are names given from different viewpoints, there are naturally, for example, an intermediate transfer system and a tandem system. A color image forming apparatus of the intermediate transfer system and tandem system (hereinafter, the tandem system is referred to as the intermediate transfer system and the tandem system) is known to obtain a high-quality full-color image. In this method, a toner image is formed on each photoconductor corresponding to yellow, magenta, cyan, and black, and a color superimposed image is formed on the intermediate transfer member, which is collectively transferred to a transfer material.

  In this tandem color image formation, there are two stages of transfer processes, a primary transfer in which the toner image is transferred from each photoconductor to the intermediate transfer body and a secondary transfer in which the toner image is transferred from the intermediate transfer body to the recording paper. Since there are two stages, cleaning of the photoreceptor after the primary transfer and cleaning of the intermediate after the secondary transfer, an image defect due to a transfer failure of the toner image and an image defect due to the cleaning are likely to occur.

  In an image forming apparatus using an intermediate transfer body, in order to avoid an increase in the size of the apparatus, there are many methods that employ a belt-shaped intermediate transfer body that can reduce the size of the apparatus, but the belt-shaped intermediate transfer body In this cleaning, the contact state between the cleaning member and the intermediate transfer member is likely to change, and cleaning defects are likely to occur. In order to solve the cleaning failure of the intermediate transfer member, several proposals have been made so far. For example, there is a method of removing residual toner on the intermediate transfer member using a cleaning device (Patent Document 1) in which a cleaning blade and a metal thin plate member are in close contact, a cleaning device (Patent Document 2) using a cleaning blade and a metal scraper, or the like. Proposed.

  However, the toner component of the developer contains a lot of low molecular components that adhere to these intermediate transfer members. In particular, when the residual monomer component contained in the toner resin component adheres to the intermediate transfer member, the contact friction with the cleaning member becomes unstable, and it is sufficient to use a cleaning device using a cleaning blade and a metal scraper. Since the intermediate transfer member cannot be cleaned, the toner easily passes through the cleaning blade, and as a result, image defects such as image unevenness are likely to occur.

  Further, defective transfer of toner from the photosensitive member to the intermediate transfer member tends to cause image defects such as a decrease in image density and missing transfer. On the other hand, there have been reports of poor transfer of toner from the intermediate transfer member to recording paper, such as character dust and sharpness deterioration associated with transfer repelling.

  In order to improve the transferability that causes this “transfer omission” and “character dust”, the surface layer of the electrophotographic photosensitive member is made to contain fine particles, the surface is made uneven, and the adhesion force of the toner on the surface of the photosensitive member Techniques such as reducing the friction, improving the transferability, and reducing the frictional force with the blade have been studied. For example, it has been reported that alkylsilsesquioxane resin fine particles are contained in a photosensitive layer (Patent Document 3). However, the alkylsilsesquioxane resin fine particles have a hygroscopic property, and in a high-humidity environment, there arises a problem that the wettability of the surface of the photoreceptor, that is, the surface energy increases, and the transferability tends to decrease. On the other hand, in order to reduce the surface energy of the photoreceptor, an electrophotographic photoreceptor containing a fluororesin powder has been reported. However, the fluororesin powder has a problem that sufficient surface strength cannot be obtained, streak failure due to scratches on the surface of the photoreceptor is likely to occur, and image blurring is likely to occur (Patent Document 4).

  On the other hand, in order to improve the transferability and cleaning performance of the intermediate transfer member, a technique for supplying a solid lubricant to the intermediate transfer member to reduce the surface energy of the intermediate transfer member has been disclosed (Patent Document 5, 6, 7). However, simply controlling the surface of such an intermediate transfer body is still insufficient for improving the total transferability of an image forming system using an intermediate transfer body having two transfer steps, particularly at high temperatures. It has been found that further improvement is necessary for the formation of high humidity and long-term copy images.

  On the other hand, looking at the electrophotographic process, the latent image forming method is roughly divided into analog image forming using a halogen lamp as a light source and digital image forming using an LED or a laser as a light source. Recently, a digital latent image forming method is rapidly becoming mainstream as a printer of a personal computer and also in an ordinary copying machine because of the ease of image processing and the development to a multifunction machine.

  In digital image formation, not only copying but also the use of producing original images increases, and digital electrophotographic image formation tends to require higher image quality.

  In response to the demand for higher image quality, research is underway to faithfully visualize a latent image on an electrophotographic photosensitive member using a polymerized toner whose shape factor and particle size distribution are controlled. When using a tandem color image forming device, the improvement in toner transferability and the improvement in cleaning properties are not as high as originally expected, and image defects due to transfer defects and toner slipping due to poor cleaning occur. Is prone to occur.

In particular, in a tandem type color image forming apparatus using an intermediate transfer body, it is important to improve the total toner transferability of both the primary transfer and the secondary transfer described above, and to improve the cleaning performance of the intermediate transfer body. Was found.
JP 2002-162839 A JP 2002-278319 A Japanese Patent Laid-Open No. 5-181291 JP-A 63-56658 JP-A-6-337598 JP-A-6-332324 JP 7-271142 A

  The present invention has been made to solve the above problems. An object of the present invention is to provide an electrophotographic image of good color using an image forming apparatus using an intermediate transfer member, and in particular, in the formation of a large number of color images, transfer from a photosensitive member to an intermediate transfer member. Image transfer from an intermediate transfer member to a recording material, and removal of residual toner components on the intermediate transfer member, thereby eliminating transfer defects due to transfer defects, character dust, or image unevenness due to poor cleaning. It is an object of the present invention to provide an electrophotographic image forming apparatus and an image forming method that reproduce a color image having a vivid hue with good sharpness. In particular, using a belt-shaped intermediate transfer body, preventing image unevenness due to poor cleaning that is likely to occur on the intermediate transfer body, transfer omission and character dust due to transfer failure, etc., and vivid colors with good sharpness An electrophotographic image forming apparatus and an image forming method for reproducing an image are provided.

  In the image forming apparatus for forming a color image using the intermediate transfer member of the present invention, the primary transferability of the color toner image from the photosensitive member to the intermediate transfer member, and the recording of each colored toner image superimposed on the intermediate transfer member As a result of detailed examination of the secondary transfer property to the material and the cleaning property of the toner on the photosensitive member and the intermediate transfer member, the residual monomer in the binder of each colored toner is the primary transfer property, the secondary transfer property, and the intermediate transfer member. It was found that it was involved in the deterioration of cleaning properties. Residual monomers in the toner are likely to adhere to the surface of the photoreceptor or intermediate transfer member, particularly to the surface of the intermediate transfer member with low surface wear, and when these residual monomers adhere to the surface of the intermediate transfer member, It was found that the primary transfer property and the secondary transfer property were deteriorated and the cleaning property of the toner of the intermediate transfer member was deteriorated to cause image unevenness, and the present invention was completed. That is, in order to improve the primary transfer property and the secondary transfer property of each colored toner and to keep the cleaning property of the intermediate transfer member good, the amount of residual monomer contained in each colored toner is not more than a certain value. At the same time, the transferability and cleaning performance can be improved by using a toner whose shape factor and particle size distribution of each colored toner are adjusted to a specific range, and comprising a cleaning means for the intermediate transfer member with a plurality of cleaning blades. The present invention has been completed.

  That is, the object of the present invention is achieved by adopting one of the following configurations.

(Claim 1)
A plurality of image forming units having at least an electrophotographic photosensitive member, a charging unit, an exposing unit, a developing unit, a transferring unit, and a cleaning unit are arranged and electrophotographic using a toner whose coloring is changed for each of the plurality of image forming units. Each colored toner image formed on the photoconductor is sequentially superimposed and transferred onto the intermediate transfer member to form a color toner image, and the color toner image is collectively retransferred onto the recording material and retransferred. In the image forming apparatus for fixing the color toner image to form a color image, the residual monomer amount of each colored toner used in the developing means of the plurality of image forming units is 300 ppm or less and remains on the intermediate transfer member. An image forming apparatus comprising an intermediate transfer member cleaning unit that removes the transferred residual toner with a plurality of cleaning blades.

(Claim 2)
A plurality of image forming units having at least an electrophotographic photosensitive member, a charging unit, an exposing unit, a developing unit, a transferring unit, and a cleaning unit are arranged and electrophotographic using a toner whose coloring is changed for each of the plurality of image forming units. Each colored toner image formed on the photoconductor is sequentially superimposed and transferred onto the intermediate transfer member to form a color toner image, and the color toner image is collectively retransferred onto the recording material and retransferred. In the image forming apparatus for fixing a color toner image to form a color image, each colored toner used for the developing means of the plurality of image forming units has toner particles having a shape factor of 1.2 to 1.6. Intermediate transfer in which 65% by weight or more of the residual monomer amount is 300 ppm or less and residual transfer toner remaining on the intermediate transfer member is removed by a plurality of cleaning blades. Image forming apparatus characterized by having an iodine cleaning means.

(Claim 3)
A plurality of image forming units having at least an electrophotographic photosensitive member, a charging unit, an exposing unit, a developing unit, a transferring unit, and a cleaning unit are arranged and electrophotographic using a toner whose coloring is changed for each of the plurality of image forming units. Each colored toner image formed on the photoconductor is sequentially superimposed and transferred onto the intermediate transfer member to form a color toner image, and the color toner image is collectively retransferred onto the recording material and retransferred. In the image forming apparatus for fixing a color toner image to form a color image, each colored toner used in the developing means of the plurality of image forming units is natural when the particle diameter of the toner particles is D (μm). The logarithm lnD is taken on the horizontal axis, and the relative frequency of the toner particles contained in the most frequent class in the histogram showing the number-based particle size distribution in which the horizontal axis is divided into a plurality of classes at intervals of 0.23 ( _1), the sum (M) is not less than 70% and a residual monomer content of the relative frequency (m ₂₎ of the toner particles contained in the following frequent the rank of the most frequent class is at 300ppm or less, wherein An image forming apparatus comprising an intermediate transfer member cleaning unit that removes residual transfer toner remaining on an intermediate transfer member with a plurality of cleaning blades.

(Claim 4)
A plurality of image forming units having at least an electrophotographic photosensitive member, a charging unit, an exposing unit, a developing unit, a transferring unit, and a cleaning unit are arranged and electrophotographic using a toner whose coloring is changed for each of the plurality of image forming units. Each colored toner image formed on the photoconductor is sequentially superimposed and transferred onto the intermediate transfer member to form a color toner image, and the color toner image is collectively retransferred onto the recording material and retransferred. In the image forming apparatus for fixing a color toner image to form a color image, each colored toner used in the developing means of the plurality of image forming units contains 50% by number or more of toner particles having no corners and a residual monomer An intermediate transfer member cleaning unit that has an amount of 300 ppm or less and removes transfer residual toner remaining on the intermediate transfer member with a plurality of cleaning blades. Image forming apparatus characterized by.

(Claim 5)
A plurality of image forming units are four image forming units, an image forming unit having black toner, an image forming unit having yellow toner, an image forming unit having magenta toner, and an image forming having cyan toner The image forming apparatus according to claim 1, comprising a unit.

(Claim 6)
6. The image forming apparatus according to claim 1, wherein the number average particle size of the black toner is 3.0 to 8.0 [mu] m.

(Claim 7)
The image forming apparatus according to claim 4, wherein the black toner is a polymerized toner.

(Claim 8)
The image forming apparatus according to claim 4, wherein the black toner, yellow toner, magenta toner, and cyan toner are polymerized toners.

(Claim 9)
The image forming apparatus according to claim 1, wherein at least one of the plurality of cleaning blades is a non-deformable member.

(Claim 10)
The image forming apparatus according to claim 9, wherein the non-deformable member is formed of a metallic scraper.

(Claim 11)
The image forming apparatus according to claim 1, wherein at least one of the plurality of cleaning blades is an elastic blade.

(Claim 12)
The image forming apparatus according to claim 11, wherein the elastic blade is a urethane rubber blade.

(Claim 13)
The image forming apparatus according to claim 1, wherein a contact angle of water on the surface of the electrophotographic photosensitive member is 90 ° or more.

(Claim 14)
The image forming apparatus according to claim 1, wherein a surface layer of the electrophotographic photosensitive member contains fluororesin particles.

(Claim 15)
The image forming apparatus according to claim 1, wherein the surface layer of the electrophotographic photosensitive member contains an antioxidant.

(Claim 16)
The image forming apparatus according to claim 1, wherein the intermediate transfer member is a belt-shaped intermediate transfer member.

(Claim 17)
An image forming method, comprising: forming an electrophotographic image using the image forming apparatus according to claim 1.

  By using the present invention, it is possible to achieve improvement in toner transfer characteristics and cleaning performance of an electrophotographic system using an intermediate transfer member, and it is possible to prevent image defects due to transfer omission, character dust and cleaning defects caused by a decrease in toner transfer. In addition, it is possible to provide an electrophotographic image forming apparatus and an image forming method capable of forming a color image with good image density and sharpness.

  The image forming apparatus of the present invention is provided with a plurality of image forming units having at least an electrophotographic photosensitive member, a charging unit, an exposure unit, a developing unit, a transfer unit, and a cleaning unit, and coloring each of the plurality of image forming units. Each colored toner image formed on the electrophotographic photosensitive member using the changed toner is sequentially superimposed and transferred onto the intermediate transfer member to form a color toner image, and the color toner image is collectively put on the recording material. An image forming apparatus that forms a color image by fixing the re-transferred color toner image, and a residual monomer amount of each colored toner used in the developing unit of the plurality of image forming units is 300 ppm or less And an intermediate transfer member cleaning means for removing residual toner remaining on the intermediate transfer member with a plurality of cleaning blades.

  In the image forming apparatus of the present invention, the toner having the residual monomer amount of 300 ppm or less is used as the toner of each of the developing units described above, so that the transfer property of the color toner image superimposed on the intermediate transfer member onto the recording paper is remarkable. Improved and removing the residual toner on the intermediate transfer body after the toner image transfer using a cleaning means having a plurality of cleaning blades, the intermediate transfer body can be stably and satisfactorily cleaned. Transfer omission due to transfer and character dust can be prevented, and image unevenness or the like due to the cleaning property of the toner on the intermediate transfer member can be remarkably improved, and a color image having excellent sharpness and vivid hue can be formed.

  As the toner used in the present invention, a polymerized toner is preferable. That is, a polymerized toner having a residual monomer amount of 300 ppm or less and a uniform shape factor, particle size distribution, and the like is less likely to contaminate the surface of the organic photoreceptor or intermediate transfer member, and hardly causes transfer failure or cleaning failure. In particular, if there is a large amount of residual monomer, character dust during transfer of toner and transfer omission tend to occur, and the cleaning properties of residual toner on the intermediate transfer member are likely to deteriorate. More preferably, the amount of residual monomer is 150 ppm or less, and most preferably 50 ppm or less.

  Here, the polymerized toner means a toner in which a toner binder resin is formed and a toner shape is formed by polymerization of a raw material monomer of the binder resin and, if necessary, subsequent chemical treatment. More specifically, it means a toner formed through a polymerization reaction such as suspension polymerization or emulsion polymerization and, if necessary, a step of fusing particles between them.

  The amount of residual monomer in the polymerized toner varies depending on the polymerization conditions of the polymerized toner. As a method for reducing the final amount of residual monomer, two types of chain transfer agents described in Japanese Patent Application No. 2002-117411 are used. Examples thereof include methods such as distillation of residual monomers by distillation under reduced pressure as described in JP-A No. 11-202539, and methods such as extending the half-life of the polymerization initiator (reducing the reaction temperature).

  The residual monomer of the toner of the present invention can be measured by a head space type gas chromatograph using a detection method used in a normal gas chromatograph such as an internal standard method. This method encloses toner in an open / close container, heats it at the time of thermal fixing of a copying machine, etc., and quickly injects the gas in the container into the gas chromatograph while the container is full of volatile components. In addition to measuring the amount of components, the headspace method of the present invention also performs MS (mass spectrometry).

  In the headspace method of the present invention, it is possible to observe all peaks of volatile components by gas chromatograph, and to quantify residual components by using an analysis method using electromagnetic interaction, with higher accuracy. Can be achieved.

  Below, the measuring method by this method is demonstrated.

<Headspace gas chromatograph measurement method>
1. Sample collection A 0.8 g sample is collected in a 20 ml headspace vial. The sample amount is weighed to 0.01 g (necessary for calculating the area per unit mass). Seal the vial with a septum using a dedicated crimper.

2. Heating the sample Place the sample in a 130 ° C. constant temperature bath and heat for 30 minutes.

3. Setting of gas chromatographic separation conditions A column coated with silicone oil SE-30 so as to have a mass ratio of 15% and packed in a column having an inner diameter of 3 mm and a length of 3 m is used as a separation column. The separation column is attached to a gas chromatograph, and He is used as a carrier to flow at 50 ml / min. The temperature of the separation column is set to 40 ° C., and measurement is performed while the temperature is increased to 260 ° C. at 15 ° C./min. Hold for 5 minutes after reaching 260 ° C.

4). Introduction of sample The vial bottle is taken out from the thermostatic chamber, immediately 1 ml of gas generated from the sample is collected with a gas tight syringe, and this is injected into the separation column.

5). Calculation A calibration curve is prepared in advance using xylene as an internal reference substance, and the concentration of each component is determined.

6). Equipment (1) Headspace conditions Headspace device
HP 7694 “Head Space” manufactured by Hewlett-Packard Company
Sampler "
Temperature conditions
Transfer line: 200 ° C
Loop temperature: 200 ° C
Sample amount: 0.8g / 20ml vial (2) GC / MS conditions
GC HP 890 manufactured by Hewlett-Packard Company
HP Hewlett Packard manufactured by MS Hewlett-Packard Company
Column: HP-624 30m x 0.25mm
Oven temperature: 40 ° C (3min) -15 ° C / min-260 ° C
Measurement mode: SIM
In the image forming apparatus of the present invention, toner having a residual monomer amount of 300 ppm or less is used as the toner of each developing unit described above, and toner having a uniform shape factor and a sharp particle size distribution as described below is used in combination. As a result, the transfer property of the color toner image superimposed on the intermediate transfer member to the recording paper is remarkably improved, and the residual toner on the intermediate transfer member after the toner image transfer is cleaned using a cleaning means having a plurality of cleaning blades. The intermediate transfer member is stably and satisfactorily cleaned, transfer omission due to two transfers, character dusting can be prevented, and unevenness of the image due to the cleaning property of the toner on the intermediate transfer member can be prevented. The color image can be remarkably improved, sharpness is good, and the hue is bright.

(1) Toner containing 65% by number or more of toner particles having a shape factor in the range of 1.2 to 1.6 When the shape factor is smaller than 1.2, the shape of the toner is close to a true sphere, and the toner photoreceptor Adhesive strength increases and cleaning defects are likely to occur. On the other hand, when the value is larger than 1.6, the toner is crushed and easily pulverized, which also causes a cleaning failure. That is, an intermediate transfer member is used for a toner containing 65% by number or more, more preferably 70% by number or more of toner particles having a shape factor in the range of 1.2 to 1.6 and a residual monomer amount of 300 ppm or less. In the conventional image forming apparatus, the transferability twice and the cleaning property of the intermediate transfer member are improved. By applying the toner having such a shape factor to the image forming apparatus of the present invention, transferability and The cleaning property can be improved, the occurrence of image defects such as image unevenness can be prevented, and a sharp electrophotographic image can be formed.

(2) Toner containing 50% by number or more of toner particles having no corners Toner particles having no corners are toner particles that substantially do not have protrusions that concentrate charges or that tend to be crushed by stress. When the ratio of toner particles without corners is 50% by number or more, more preferably 70% by number or more, generation of fine particles is less likely to occur due to stress with the developer conveying member and the like. By applying a toner containing 50% by number or more of toner particles having no corners and a residual monomer amount of 300 ppm or less to the image forming apparatus of the present invention, it is possible to prevent transfer failure and cleaning failure due to toner generation. For a long time, transferability and cleaning properties can be improved, image defects such as image unevenness can be prevented, and sharp electrophotographic images can be formed. .

(3) When the particle diameter of toner particles is D (μm), the horizontal axis represents the natural logarithm lnD, and the horizontal axis represents a number-based particle size distribution divided into a plurality of classes at intervals of 0.23. The sum (M) of the relative frequency (m ₁ ) of the toner particles contained in the most frequent class and the relative frequency (m ₂ ) of the toner particles contained in the next most frequent class is 70% or more. Contained toner A toner having a relative frequency (m ₁ ) and a sum (M) of the relative frequency (m ₂ ) of 70% or more makes the particle size distribution of the toner particles constituting the toner sharp and stable. As a result, transferability and cleaning performance of the image become possible, and as a result, by applying to the image forming apparatus of the present invention, transferability and cleaning performance can be improved over a long period of time, preventing occurrence of image defects such as image unevenness, Sharp electrophotography It can be formed.

  The toner preferably has a number average primary particle size of 3 to 8 μm. When the toner particles are formed by a polymerization method, the particle size can be controlled by the concentration of the aggregating agent, the amount of the organic solvent added, the fusing time, and further the composition of the polymer itself.

  When the number average particle diameter is 3 to 8 μm, it is possible to reduce the presence of excessively adhering toner or low adhering toner on the developer conveying member in the fixing step, and developability over a long period of time. And the transfer efficiency is increased, the image quality of halftone is improved, and the image quality of fine lines and dots is improved.

  The shape factor of the toner is expressed by the following formula and indicates the degree of roundness of the toner particles.

Shape factor = ((maximum diameter / 2) ² × π) / projection area Here, the maximum diameter is the distance between the parallel lines when the projected image of toner particles on a plane is sandwiched between two parallel lines. The maximum particle width. The projected area refers to the area of the projected image of the toner particles on the plane.

  This shape factor is obtained by taking a photograph in which toner particles are magnified 2000 times with a scanning electron microscope, and then analyzing a photographic image using “SCANNING IMAGE ANALYZER” (manufactured by JEOL Ltd.) based on this photograph. Was measured. At this time, the shape factor of the present invention was measured by the above formula using 100 toner particles.

  In the toner of the present invention, the number of toner particles having a shape factor in the range of 1.2 to 1.6 is 65% by number or more, preferably 70% by number or more.

  The method for controlling the shape factor is not particularly limited. For example, a method in which toner particles are sprayed into a hot air stream, a method in which toner particles are repeatedly applied with mechanical energy due to impact force in a gas phase, or a method in which a toner is not dissolved in a solvent and a swirl flow is applied. However, in the present invention, it is preferable to produce a shape factor and the like within the scope of the present invention using a polymerized toner produced by a polymerization method.

  In order to uniformly control the shape factor of the toner without variation in lots, the toner being formed in the production process of the polymerized toner, that is, the process of polymerizing, fusing and controlling the shape of the resin particles (polymer particles) An appropriate process end time may be determined while monitoring the characteristics of the particles (colored particles).

  Monitoring means that a measuring device is incorporated in-line, and process conditions are controlled based on the measurement result. In other words, in the case of a polymerization method toner that is formed by incorporating measurement such as shape in-line, for example, by associating or fusing resin particles in an aqueous medium, the shape and particle size are measured while performing sequential sampling in the fusing step. The reaction is stopped when the desired shape is obtained.

  Although it does not specifically limit as a monitoring method, The flow type particle image analyzer FPIA-2000 (made by Toa Medical Electronics Co., Ltd.) can be used. This apparatus is suitable because the shape can be monitored by performing image processing in real time while passing the sample liquid. That is, a pump or the like is used from the reaction field and is constantly monitored to measure the shape and the like, and the reaction is stopped when the desired shape is obtained.

The number particle size distribution and the number variation coefficient of the toner are measured by a Coulter Counter TA-II or Coulter Multisizer (manufactured by Coulter). In the present invention, a Coulter Multisizer is used, and an interface (manufactured by Nikkaki Co., Ltd.) that outputs a particle size distribution and a personal computer are connected. The aperture used in the Coulter Multisizer was 100 μm, and the volume and number of toners of 2 μm or more were measured to calculate the particle size distribution and average particle size. The number particle size distribution represents the relative frequency of the toner particles with respect to the particle size, and the number average particle size represents the median diameter in the number particle size distribution.

  The toner particles having no corners are toner particles that substantially do not have protrusions that concentrate electric charges or protrusions that easily wear due to stress. The toner particles having no corners will be described with reference to FIG. That is, as shown in FIG. 5A, when the major axis of the toner particles T is L, a circle C having a radius (L / 10) is in contact with the peripheral line of the toner particles T at one point. A case where the circle C does not substantially protrude outside the toner T when the inner side is rolled is referred to as “toner particles having no corners”. “A case where the protrusion does not substantially protrude” refers to a case where the protrusion having the protruding circle is one or less. The “major diameter of toner particles” refers to the width of a particle that maximizes the interval between the parallel lines when the projected image of the toner particles on a plane is sandwiched between two parallel lines. 5B and 5C show projection images of toner particles having corners, respectively.

  The measurement of toner without corners was performed as follows. First, an enlarged photograph of the toner particles is taken with a scanning electron microscope, and further enlarged to obtain a 15,000 times photographic image. The photographic image is then measured for the presence or absence of the corners. This measurement was performed on 100 toner particles.

  A method for obtaining toner having no corners is not particularly limited. For example, as described above as a method for controlling the shape factor, a method in which toner particles are sprayed into a hot air stream, a method in which toner particles are repeatedly applied with mechanical energy by impact force in a gas phase, or a toner is dissolved. It can be obtained by adding in a solvent that does not, and applying a swirling flow. However, in consideration of production cost and energy cost, a polymerized toner by a polymerization method is preferable.

  For example, in a polymerization toner formed by associating or fusing resin particles, the fusing particle surface has many irregularities at the fusing stop stage, and the surface is not smooth, but the temperature in the shape control step, By making the conditions such as the number of revolutions of the stirring blade and the stirring time appropriate, a toner having no corners can be obtained. These conditions vary depending on the physical properties of the resin particles. For example, by setting the rotational speed to be higher than the glass transition temperature of the resin particles, the toner can be formed with a smooth surface and no corners.

  The toner of the present invention preferably has a number average particle diameter of 3 to 8 μm. When the toner particles are formed by a polymerization method, the particle size can be controlled by the concentration of the aggregating agent, the amount of the organic solvent added, the fusing time, and further the composition of the polymer itself.

As the polymerized toner preferably used in the present invention, when the particle diameter of the toner particle is D (μm), the natural logarithm lnD is taken on the horizontal axis, and the horizontal axis is divided into a plurality of classes at intervals of 0.23. In the histogram showing the particle size distribution, the relative frequency (m ₁ ) of the toner particles included in the most frequent class and the relative frequency (m ₂ ) of the toner particles included in the most frequent class after the most frequent class. A toner having a sum (M) of 70% or more is preferable.

The method for controlling the sum (M) of the relative frequency (m ₁ ) and the relative frequency (m ₂ ) is not particularly limited. For example, a method of classifying toner particles by wind force can be used, but in order to make the sum (M) 70% or more, classification in a liquid is effective in the production process of the polymerized toner. As a method of classifying in this liquid, there is a method of separating and collecting toner particles according to a difference in sedimentation speed caused by a difference in toner particle diameter by using a centrifuge and controlling the rotation speed.

When the sum (M) of the relative frequency (m ₁ ) and the relative frequency (m ₂ ) is 70% or more, the dispersion of the particle size distribution of the toner particles is narrowed, so that the toner is used in the image forming process. The occurrence of selective development can be reliably suppressed.

  In the present invention, the histogram showing the particle size distribution based on the number is a natural logarithm lnD (D: particle size of individual toner particles) having a plurality of classes (0 to 0.23: 0.23) at intervals of 0.23. 0.46: 0.46-0.69: 0.69-0.92: 0.92-1.15: 1.15-1.38: 1.38-1.61: 1.61-1. 84: 1.84 to 2.07: 2.07 to 2.30: 2.30 to 2.53: 2.53 to 2.76, and so on). This histogram is prepared by transferring the particle size data of a sample measured by a Coulter Multisizer to a computer via an I / O unit according to the following conditions and using the particle size distribution analysis program in the computer. is there.

〔Measurement condition〕
(1) Aperture: 100 μm
(2) Sample preparation method: Electrolyte [ISOTON R-11 (manufactured by Coulter Scientific Japan)] 50-100 ml, an appropriate amount of a surfactant (neutral detergent) is added and stirred, and 10-20 mg of a measurement sample is added thereto. Add This system is prepared by dispersing for 1 minute with an ultrasonic disperser.

  Among the methods for controlling the shape factor, the polymerization toner is preferable because it is simple as a production method and has excellent surface uniformity as compared with the pulverized toner.

  The polymerized toner is produced by emulsion polymerization of monomers in a suspension polymerization method or in a solution to which an emulsion of necessary additives is added to produce fine polymer particles, and then an organic solvent, an aggregating agent, etc. It can manufacture by the method of adding and associating. A method of preparing by mixing with a dispersion liquid such as a release agent and a colorant necessary for the composition of the toner at the time of association, and a toner component such as a release agent and a colorant dispersed in the monomer And a method of emulsion polymerization. Here, the association means that a plurality of resin particles and colorant particles are fused.

  That is, various constituent materials such as a colorant and, if necessary, a release agent, a charge control agent, and a polymerization initiator are added to the polymerizable monomer, and a homogenizer, a sand mill, a sand grinder, an ultrasonic disperser, etc. Various constituent materials are dissolved or dispersed in the polymerizable monomer. The polymerizable monomer in which these various constituent materials are dissolved or dispersed is dispersed in oil droplets having a desired size as a toner in an aqueous medium containing a dispersion stabilizer using a homomixer or a homogenizer. Thereafter, the stirring mechanism is transferred to a reaction apparatus which is a stirring blade described later, and the polymerization reaction is advanced by heating. After completion of the reaction, the dispersion stabilizer is removed, filtered, washed, and dried to prepare a toner.

  Further, as a method for producing the toner of the present invention, a method of preparing by associating or fusing resin particles in an aqueous medium can also be mentioned. The method is not particularly limited, and examples thereof include methods disclosed in JP-A-5-265252, JP-A-6-329947, and JP-A-9-15904. That is, a method of associating a plurality of fine particles composed of resin particles and colorants, etc., or particles composed of resin and colorant, in particular, after dispersing them in water using an emulsifier, the critical aggregation concentration The above flocculant is added for salting out, and at the same time, the formed polymer itself is heated and fused at a temperature higher than the glass transition temperature to gradually grow the particle size while forming fused particles. Then, a large amount of water was added to stop the particle size growth, and the particle surface was smoothed while heating and stirring to control the shape, and the particles were heated and dried in a fluidized state while containing water, whereby a toner was obtained. Can be formed. Here, an organic solvent that is infinitely soluble in water may be added simultaneously with the flocculant.

  Note that materials and manufacturing methods for producing a uniform toner such as a shape factor used in the present invention, a polymerization toner reaction device, and the like are described in detail in JP-A-2000-214629.

  The binder resin contained in the toner is not particularly limited and is generally known as a styrene resin, an acrylic resin, a styrene-acrylic resin, a polyester resin, a styrene-butadiene resin, an epoxy resin, or the like. A binder resin can be used, but a styrene-acrylic resin is preferable as the binder resin of the polymerized toner formed in the aqueous medium.

  Examples of the resin constituting the styrene resin, acrylic resin, and styrene-acrylic resin include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-chlorostyrene, 3,4- Dichlorostyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, pt-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, p- styrene or styrene derivatives such as n-decylstyrene, pn-dodecylstyrene, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-methacrylate -Octyl, 2-ethylhexyl methacrylate, Methacrylate derivatives such as stearyl acrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-acrylate -Specific examples of acrylic acid ester derivatives such as butyl, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, phenyl acrylate, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, etc. As monomers constituting the resin, these can be used alone or in combination.

  Specific examples of other vinyl polymers include olefins such as ethylene, propylene and isobutylene, halogen-based vinyls such as vinyl chloride, vinylidene chloride, vinyl bromide, vinyl fluoride and vinylidene fluoride, and propionic acid. Vinyl esters such as vinyl, vinyl acetate and vinyl benzoate, vinyl ethers such as vinyl methyl ether and vinyl ethyl ether, vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and vinyl hexyl ketone, N-vinyl carbazole and N-vinyl N-vinyl compounds such as indole and N-vinylpyrrolidone, vinyl compounds such as vinylnaphthalene and vinylpyridine, acrylonitrile, methacrylonitrile, acrylamide, N-butylacrylamide, N, N-dibutylacrylamide, methacrylate Amide, N- methacrylamide, there are acrylic acid or methacrylic acid derivatives such as N- octadecyl acrylamide. These vinyl monomers can be used alone or in combination.

  Furthermore, examples of monomers for obtaining a carboxylic acid polymer with a styrene-acrylic resin (vinyl resin) include acrylic acid, methacrylic acid, α-ethylacrylic acid, fumaric acid, maleic acid, itaconic acid, silica. Cinnamic acid, maleic acid monobutyl ester, maleic acid monooctyl ester, cinnamic acid anhydride, alkenyl succinic acid methyl half ester and the like.

  Further, a cross-linking agent such as divinylbenzene, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate may be added.

  The polyester resin is a resin obtained by condensation polymerization of a divalent or higher carboxylic acid and a divalent or higher alcohol component. Examples of divalent carboxylic acids include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutamic acid, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, malonic acid, n- Examples include dodecyl succinic acid, n-dodecenyl succinic acid, isododecyl succinic acid, isododecenyl succinic acid, n-octyl succinic acid, and n-octenyl succinic acid. These acid anhydrides can also be used.

  Examples of the divalent alcohol component constituting the polyester resin include polyoxypropylene (2.2) -2, 2-bis (4-hydroxyphenyl) propane, polyoxypropylene (3.3) -2, 2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (2.0) -polyoxyethylene (2.0) Etherified bisphenol such as -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (6) -2,2-bis (4-hydroxyphenyl) propane, ethylene glycol, diethylene glycol, triethylene glycol, 1, 2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol 1,4 butenediol, neopentyl glycol, 1,5-pentane glycol, 1,6-hexane glycol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, bisphenol A Bisphenol Z, hydrogenated bisphenol A, and the like.

  Examples of the polyester resin having a crosslinked structure include the following trivalent carboxylic acids such as 1,2,4-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, and 1,2,4-naphthalenetricarboxylic acid. 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra ( Methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, emporic trimer acid, and the like. These acid anhydrides or polyhydric alcohol components, specifically sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaery Ritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentatriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, tri A crosslinked polyester resin can also be obtained by adding methylolpropane, 1,3,5-trihydroxymethylbenzene or the like.

  In the present invention, black toner (hereinafter also referred to as toner Bk), yellow toner (hereinafter also referred to as toner Y), magenta toner (hereinafter also referred to as toner M), cyan toner (hereinafter referred to as toner C). Examples of the colorant used in the present invention include inorganic pigments and organic pigments.

  A conventionally well-known thing can be used as an inorganic pigment. Specific inorganic pigments are exemplified below.

  Examples of black pigments include carbon black such as furnace black, channel black, acetylene black, thermal black, and lamp black, and magnetic powder such as magnetite and ferrite.

  These inorganic pigments can be used alone or in combination as required. Moreover, the addition amount of a pigment is 2-20 mass% with respect to a polymer, Preferably 3-15 mass% is selected.

  When used as a magnetic toner, the above-mentioned magnetite can be added. In this case, it is preferable to add 20 to 60% by mass in the toner from the viewpoint of imparting predetermined magnetic properties.

  Conventionally known organic pigments can also be used. Specific organic pigments are exemplified below.

  Examples of the magenta or red pigment (magenta color system) include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. And CI Pigment Red 222.

  Examples of pigments for orange or yellow (yellow type) include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. And CI Pigment Yellow 138.

  Examples of pigments for green or cyan (cyan color) include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. And CI Pigment Green 7.

  These organic pigments can be used alone or in combination as required. Moreover, the addition amount of a pigment is 2-20 mass% with respect to a polymer, Preferably 3-15 mass% is selected.

  The colorant can also be used after surface modification. As the surface modifier, conventionally known ones can be used, and specifically, silane coupling agents, titanium coupling agents, aluminum coupling agents and the like can be preferably used.

  To the toner obtained in the present invention, so-called external additives can be added and used for the purpose of improving fluidity and improving cleaning properties. As described above, these external additives are not particularly limited, and various inorganic particles, organic particles and lubricants can be used.

  In addition to the external additive particles, a lubricant may be added to the toner as an external additive. Examples of lubricants include, for example, zinc stearate, aluminum, copper, magnesium, calcium, etc., zinc oleate, manganese, iron, copper, magnesium, etc., zinc palmitate, copper, magnesium, calcium, etc. And salts of higher fatty acids such as zinc of linoleic acid, salts of calcium, etc., zinc of ricinoleic acid, salts of calcium, etc.

  The addition amount of these lubricants is preferably about 0.1 to 5% by mass with respect to the toner.

  In the toner forming step, the above-described external additives may be added to the toner particles obtained above for the purpose of improving fluidity, chargeability, and cleaning properties, for example. As a method for adding the external additive, various known mixing apparatuses such as a Turbuler mixer, a Henschel mixer, a Nauter mixer, and a V-type mixer can be used.

  In addition to the binder resin and the colorant, the toner may be added with a material capable of imparting various functions as an additive for the toner. Specific examples include a release agent and a charge control agent.

  In addition, as a mold release agent, various well-known things, specifically, olefin type waxes, such as polypropylene and polyethylene, these modified substances, natural waxes, such as carnauba wax and rice wax, fatty acid bisamide, etc. Examples thereof include amide waxes. It has already been mentioned that these are added as release agent particles and are preferably salted out / fused together with resin and colorant.

Similarly, various known charge control agents and those that can be dispersed in water can be used. Specific examples include nigrosine dyes, naphthenic acid or higher fatty acid metal salts, alkoxylated amines, quaternary ammonium salt compounds, azo metal complexes, salicylic acid metal salts or metal complexes thereof.
<Developer>
The toner used in the present invention may be a one-component developer or a two-component developer, but is preferably a two-component developer.

  When used as a one-component developer, there is a method in which the toner is used as it is as a non-magnetic one-component developer. Usually, however, the toner particles contain about 0.1 to 5 μm of magnetic particles as a magnetic one-component developer. Use. As a method for its inclusion, it is usually contained in non-spherical particles in the same manner as the colorant.

  Further, it can be mixed with a carrier and used as a two-component developer. In this case, conventionally known materials such as metals such as iron, ferrite, and magnetite, and alloys of these metals with metals such as aluminum and lead are used as the magnetic particles of the carrier. Ferrite particles are particularly preferable. The magnetic particles preferably have a volume average particle size of 15 to 100 μm, more preferably 25 to 60 μm.

  The volume average particle diameter of the carrier can be typically measured by a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by SYMPATEC) equipped with a wet disperser.

  The carrier is preferably a carrier in which magnetic particles are further coated with a resin, or a so-called resin dispersion type carrier in which magnetic particles are dispersed in a resin. The resin composition for coating is not particularly limited, and for example, olefin resin, styrene resin, styrene / acrylic resin, silicone resin, ester resin, or fluorine-containing polymer resin is used. The resin for constituting the resin-dispersed carrier is not particularly limited, and known resins can be used. For example, a styrene acrylic resin, a polyester resin, a fluorine resin, a phenol resin, or the like can be used. it can.

  Next, the photoconductor used in the present invention will be described in detail.

  The electrophotographic photosensitive member used in the image forming apparatus of the present invention may be either an inorganic photosensitive member or an organic photosensitive member. However, when forming a latent image, color sensitivity to laser light used for image exposure, An organic photoreceptor is preferable from the viewpoint of good productivity.

  Here, the organic photoconductor means an electrophotographic photoconductor formed by giving an organic compound at least one of a charge generation function and a charge transport function indispensable for the configuration of the electrophotographic photoconductor. It contains all known organic electrophotographic photoreceptors such as a photoreceptor composed of an organic charge generating material or an organic charge transport material, a photoreceptor composed of a polymer complex with a charge generating function and a charge transport function.

  In the electrophotographic photoreceptor used in the image forming apparatus of the present invention, it is preferable that the surface of the photoreceptor is made to have low surface energy properties and the transferability of toner from the photoreceptor to the intermediate transfer member is improved. As a measure for this, one is to make the surface layer of the photoreceptor into a surface layer containing fluorine resin particles in the present invention, and the other is to supply a surface energy reducing agent to the surface of the photoreceptor. As a result, the surface energy of the photosensitive member can be reduced, and the transferability of toner from the photosensitive member to the intermediate transfer member can be improved. By combining the reduction of the surface energy of the photoconductor and the use of the toner group having the toner turbidity described above, the primary transferability and secondary transfer of the toner of the image forming apparatus using the intermediate transfer body are used. By combining the transfer efficiency of both the color and the synergistic effect, it is possible to provide a color electrophotographic image having good sharpness and good hue reproduction for both the character image and the color image.

  In the electrophotographic photoreceptor of the present invention, the surface layer preferably has a contact angle with water of 90 ° or more by reducing the surface energy. By making the contact angle with water 90 ° or more, it is possible to improve the cleaning property of the toner and the like and improve the transfer property of the toner from the photosensitive member to the intermediate transfer member.

  Examples of the fluorine resin particles include, for example, polytetrafluoroethylene, polyvinylidene fluoride, polytrifluoroethylene chloride, polyvinyl fluoride, polytetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, polytetrafluoroethylene- Examples include resin particles such as hexafluoropropylene copolymer, polyethylene-trifluoride ethylene copolymer, polytetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer, and volume average particle diameter. The thickness is preferably 0.05 to 10 μm, more preferably 0.1 to 5 μm. The amount of the fluororesin particles contained in the photoreceptor of the present invention is preferably 0.1 to 90% by mass, more preferably 1 to 50% by mass with respect to the binder resin of the surface layer of the photoreceptor. If the amount is less than 0.1%, sufficient photosensitive durability and lubricity cannot be imparted to the photosensitive layer, and the improvement of the primary transfer property of the toner is small, resulting in a decrease in image density, transfer loss, and sharpness. Deterioration is likely to occur. If it exceeds 90% by mass, the formation of the surface layer tends to be difficult.

  The volume average particle diameter of the fluororesin particles is measured by a laser diffraction / scattering particle size distribution measuring apparatus “LA-700” (manufactured by Horiba, Ltd.). The surface contact angle of the photosensitive member is measured by using a contact angle meter (CA-DT-A type: manufactured by Kyowa Interface Science Co., Ltd.) in an environment of 20 ° C. and 50% RH.

  Hereinafter, a specific configuration of the photoreceptor used in the present invention will be described.

Conductive Support As the conductive support used in the photoreceptor of the present invention, a sheet-like or cylindrical conductive support is used.

  The cylindrical conductive support of the present invention means a cylindrical support necessary for forming an endless image by rotating, and the straightness is in the range of 0.1 mm or less and the deflection is 0.1 mm or less. Certain conductive supports are preferred. Exceeding the range of straightness and shake makes it difficult to form a good image.

As a material for the conductive support, a metal drum such as aluminum or nickel, a plastic drum deposited with aluminum, tin oxide, indium oxide, or the like, or a paper / plastic drum coated with a conductive substance can be used. The conductive support preferably has a specific resistance of 10 ³ Ωcm or less at room temperature.

  As the conductive support used in the present invention, one having an alumite film that has been sealed on the surface thereof may be used. The alumite treatment is usually performed in an acidic bath such as chromic acid, sulfuric acid, oxalic acid, phosphoric acid, boric acid, sulfamic acid, etc., but anodizing treatment in sulfuric acid gives the most preferable result. In the case of anodizing in sulfuric acid, the sulfuric acid concentration is preferably 100 to 200 g / l, the aluminum ion concentration is 1 to 10 g / l, the liquid temperature is about 20 ° C., and the applied voltage is preferably about 20 V. It is not limited. The average film thickness of the anodized film is usually 20 μm or less, particularly preferably 10 μm or less.

Intermediate layer In the present invention, it is preferable to provide an intermediate layer having a barrier function between the conductive support and the photosensitive layer, and in particular, an intermediate layer in which titanium oxide fine particles are dispersed and contained in a binder resin such as polyamide. preferable. The average particle diameter of the titanium oxide particles is preferably in the range of 10 nm to 400 nm in terms of number average primary particle diameter, and is preferably 15 nm to 200 nm. If it is less than 10 nm, the effect of preventing the occurrence of moire by the intermediate layer is small. On the other hand, if it is larger than 400 nm, the titanium oxide particles in the intermediate layer coating solution are likely to settle, and as a result, the uniform dispersibility of the titanium oxide particles in the intermediate layer is poor, and the black spots are likely to increase. An intermediate layer coating liquid using titanium oxide particles having a number average primary particle size in the above range has good dispersion stability, and the intermediate layer formed from such a coating liquid has an environmental characteristic in addition to the function of preventing the occurrence of black spots. Is good and has cracking resistance.

  The shape of the titanium oxide particles used in the present invention includes a dendritic shape, a needle shape, a granular shape, and the like. The titanium oxide particles having such a shape are, for example, titanium oxide particles, anatase type, rutile as crystal types. There are types, amorphous types, and the like. Any crystal type may be used, or two or more crystal types may be mixed and used. Among them, the rutile type and granular type are the best.

  The titanium oxide particles of the present invention are preferably surface-treated. Among these, it is preferable to perform a plurality of surface treatments, and among the plurality of surface treatments, the last surface treatment is a surface treatment using a reactive organosilicon compound. In addition, at least one of the surface treatments is at least one surface treatment selected from alumina, silica, and zirconia, and finally a surface treatment using a reactive organosilicon compound. It is preferable to carry out.

  Alumina treatment, silica treatment, and zirconia treatment are treatments for precipitating alumina, silica, or zirconia on the surface of titanium oxide particles, and alumina, silica, and zirconia deposited on these surfaces are water of alumina, silica, and zirconia. Japanese products are also included. The surface treatment of the reactive organosilicon compound means using a reactive organosilicon compound in the treatment liquid.

  In this way, when the surface treatment of the titanium oxide particles is performed at least twice, the surface of the titanium oxide particles is uniformly coated (treated), and when the surface-treated titanium oxide particles are used for the intermediate layer, the intermediate layer It is possible to obtain a good photoconductor having good dispersibility of the titanium oxide particles therein and causing no image defects such as black spots.

  Preferable reactive organosilicon compounds used for the surface treatment include various alkoxysilanes such as methyltrimethoxysilane, n-butyltrimethoxysilane, n-hexycyltrimethoxysilane, dimethyldimethoxysilane, and methylhydrogenpolysiloxane.

Photosensitive layer The photosensitive layer configuration of the photoreceptor of the present invention may be a single-layer photosensitive layer configuration in which the intermediate layer has a charge generation function and a charge transport function in one layer, but more preferably the function of the photosensitive layer. The charge generation layer (CGL) and the charge transport layer (CTL) may be separated from each other. By adopting a configuration in which the functions are separated, an increase in the residual potential due to repeated use can be controlled to be small, and other electrophotographic characteristics can be easily controlled according to the purpose. In the negatively charged photoconductor, it is preferable that a charge generation layer (CGL) is formed on the intermediate layer and a charge transport layer (CTL) is formed thereon. In the positively charged photoconductor, the order of the layer configuration is the reverse of that in the negatively charged photoconductor. The most preferred photosensitive layer structure of the present invention is a negatively charged photoreceptor structure having the function separation structure.

  The structure of the photosensitive layer of the function-separated negatively charged photoreceptor will be described below.

Charge generation layer The charge generation layer contains a charge generation material (CGM). Other substances may contain a binder resin and other additives as necessary.

  In the electrophotographic photoreceptor of the present invention, a phthalocyanine pigment, an azo pigment, a perylene pigment, an azulenium pigment, or the like can be used alone or in combination as a charge generating material.

  When a binder is used as the CGM dispersion medium in the charge generation layer, a known resin can be used as the binder, but the most preferred resins include formal resin, butyral resin, silicone resin, silicone-modified butyral resin, phenoxy resin, and the like. Can be mentioned. The ratio of the binder resin to the charge generating material is preferably 20 to 600 parts by mass with respect to 100 parts by mass of the binder resin. By using these resins, the increase in residual potential associated with repeated use can be minimized. The thickness of the charge generation layer is preferably 0.1 μm to 2 μm.

Charge Transport Layer The charge transport layer contains a charge transport material (CTM) and a binder resin that forms a film by dispersing CTM. Other substances may contain additives such as antioxidants as necessary.

  A known charge transport material (CTM) can be used as the charge transport material (CTM). For example, a triphenylamine derivative, a hydrazone compound, a styryl compound, a benzidine compound, a butadiene compound, or the like can be used. These charge transport materials are usually dissolved in a suitable binder resin to form a layer.

  The binder resin used for the charge transport layer (CTL) may be either a thermoplastic resin or a thermosetting resin. For example, polystyrene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, polyurethane resin, phenol resin, polyester resin, alkyd resin, polycarbonate resin, silicone resin, melamine resin, and these resins A copolymer resin containing two or more of the repeating unit structures. In addition to these insulating resins, high molecular organic semiconductors such as poly-N-vinylcarbazole can be used. Of these, polycarbonate resins are most preferred because of their low water absorption and good CTM dispersibility and electrophotographic characteristics.

  The ratio of the binder resin to the charge transport material is preferably 10 to 200 parts by mass with respect to 100 parts by mass of the binder resin. The thickness of the charge transport layer is preferably 10 to 40 μm.

  The charge transport layer may be composed of two or more layers. When the charge transport layer is composed of two or more layers, it is preferable that the uppermost charge transport layer contains the above-mentioned fluorine-based resin particles to form a surface layer of the photoreceptor.

  The most preferable layer structure of the photoconductor of the present invention has been exemplified above, but other photoconductor layer configurations may be used in the present invention.

  FIG. 1 is a cross-sectional configuration diagram of a color image forming apparatus showing an embodiment of the present invention.

  This color image forming apparatus is called a tandem type color image forming apparatus, and a plurality of sets of image forming units (image forming units) 10Y, 10M, 10C, and 10Bk, a belt-shaped intermediate transfer body unit 7, and paper feeding It comprises a conveying means 21 and a fixing means 24. A document image reading device SC is disposed on the upper part of the main body A of the image forming apparatus.

  An image forming unit 10Y that forms a yellow image includes a charging unit 2Y, an exposure unit 3Y, a developing unit 4Y, and a primary transfer unit disposed around a drum-shaped photoconductor 1Y as a first image carrier. A primary transfer roller 5Y and a cleaning means 6Y are provided. An image forming unit 10M that forms a magenta image includes a drum-shaped photosensitive member 1M as a first image carrier, a charging unit 2M, an exposure unit 3M, a developing unit 4M, a primary transfer roller 5M as a primary transfer unit, It has a cleaning means 6M. An image forming unit 10C for forming a cyan image includes a drum-shaped photoreceptor 1C as a first image carrier, a charging unit 2C, an exposure unit 3C, a developing unit 4C, and a primary transfer roller 5C as a primary transfer unit. It has cleaning means 6C. The image forming unit 10Bk that forms a black image includes a drum-shaped photoreceptor 1Bk as a first image carrier, a charging unit 2Bk, an exposure unit 3Bk, a developing unit 4Bk, a primary transfer roller 5Bk as a primary transfer unit, and a cleaning unit. 6Bk.

  The belt-shaped intermediate transfer body unit 7 includes a belt-shaped intermediate transfer body 70 as a second image carrier having a semiconductive endless belt shape that is wound around a plurality of rollers and is rotatably supported.

  Each colored image formed by the image forming units 10Y, 10M, 10C, and 10Bk is sequentially transferred onto a rotating belt-shaped intermediate transfer body 70 by primary transfer rollers 5Y, 5M, 5C, and 5Bk as primary transfer means. Thus, a synthesized color image is formed. A sheet P as a recording material (a support for carrying a fixed final image: for example, plain paper, transparent sheet, etc.) housed in the sheet feeding cassette 20 is fed by a sheet feeding means 21 and has a plurality of intermediate rollers. After passing through 22A, 22B, 22C, 22D and the registration roller 23, it is conveyed to the secondary transfer roller 5A as the secondary transfer means, and is secondarily transferred onto the paper P, and the color images are collectively transferred. The paper P on which the color image has been transferred is fixed by the fixing unit 24, is sandwiched between the paper discharge rollers 25, and is placed on a paper discharge tray 26 outside the apparatus.

  On the other hand, after the color image is transferred to the paper P by the secondary transfer roller 5A as the secondary transfer means, the residual toner is removed by the cleaning means 6A from the belt-shaped intermediate transfer body 70 from which the paper P is separated by curvature.

  During the image forming process, the primary transfer roller 5Bk is always in pressure contact with the photoreceptor 1Bk. The other primary transfer rollers 5Y, 5M, and 5C are in pressure contact with the corresponding photoreceptors 1Y, 1M, and 1C, respectively, only during color image formation.

  The secondary transfer roller 5A comes into pressure contact with the belt-shaped intermediate transfer member 70 only when the sheet P passes through the secondary transfer roller 5A and secondary transfer is performed.

  Further, the housing 8 can be pulled out from the apparatus main body A through the support rails 82L and 82R.

  The housing 8 includes image forming units 10Y, 10M, 10C, and 10Bk and a belt-shaped intermediate transfer body unit 7.

  The image forming units 10Y, 10M, 10C, and 10Bk are arranged in tandem in the vertical direction. A belt-shaped intermediate transfer body unit 7 is disposed on the left side of the photoreceptors 1Y, 1M, 1C, and 1Bk in the drawing. The belt-shaped intermediate transfer body unit 7 includes a belt-shaped intermediate transfer body 70 that can be rotated by winding rollers 71, 72, 73, 74, and 75, primary transfer rollers 5Y, 5M, 5C, and 5Bk, and a cleaning unit 6A. Consists of.

  The image forming units 10Y, 10M, 10C, and 10Bk and the belt-shaped intermediate transfer body unit 7 are integrally pulled out from the main body A by the drawer operation of the housing 8.

  A support rail 82 </ b> L on the left side of the housing 8 in the figure is disposed on the left side of the belt-shaped intermediate transfer body 70 and in the upper space of the fixing unit 24. The support rail 82R on the right side of the housing 8 in the drawing is disposed near the lower part of the lowermost developing means 4Bk. The support rail 82R is disposed at a position that does not hinder the operation of attaching and detaching the developing units 4Y, 4M, 4C, and 4Bk to the housing 8.

  The right side of the photoconductors 1Y, 1M, 1C, and 1Bk in the housing 8 is surrounded by the developing means 4Y, 4M, 4C, and 4Bk, and the lower side in the figure is the charging means 2Y, 2M, 2C, and 2Bk, and the cleaning means 6Y. , 6M, 6C, 6Bk, etc., and the left side in the figure is surrounded by a belt-like intermediate transfer member 70.

  Among them, the photosensitive member, the cleaning unit, the charging unit and the like form one photosensitive unit, and the developing unit and the toner replenishing device form one developing unit.

  The image forming apparatus of the present invention is characterized in that a plurality of cleaning blades are used as cleaning means for residual toner on the intermediate transfer member. By removing the residual toner on the intermediate transfer member with the plurality of cleaning blades, even if toner having a little residual monomer amount adheres on the intermediate transfer member, the adhered toner can be more effectively removed. it can.

  FIG. 2 shows an example of the cleaning means for the intermediate transfer member.

  The intermediate transfer member cleaning means of the present invention has a plurality of cleaning blades. In one embodiment of the present invention, the belt-like intermediate transfer member cleaning means 6A is a cleaner that opens to face the toner image carrying surface of the belt-like intermediate transfer member 70, as shown in FIGS. It has a case 61C, facing the opening of the cleaner case 61C, and two cleaning blades in order from the upstream side in the moving direction of the belt-shaped intermediate transfer body 70, that is, an elastic blade 61A such as a urethane rubber blade and a metal such as SUS. A scraper 61B is provided. In the present embodiment, the attachment structure of the elastic blade 61A and the metal scraper 61B is provided such that a swing arm 61D is swingably provided in the cleaner case 61C with one end side as a swing fulcrum 61E. The holder 61F serves as a holder 61F, and the elastic blade 61A and one end of the metal scraper 61B are fixed to the holder 61F, and a return spring 61G is interposed between the free end of the swing arm 61D and the cleaner case 61C. The swing arm 61D is swung between a cleaning position and a retract position by a drive mechanism (not shown). In FIG. 2A, a brush roll 61H is provided at the lower edge of the opening of the cleaner case 61C and collects the toner removed by the elastic blade and the metal scraper. 61I is a flicker that adsorbs the toner adhering to the brush roll 61H, and the toner adhering to the flicker is removed by a 61J scraper and collected by the conveying screw 61K.

  In particular, in the present embodiment, various conditions (free length, contact pressure, thickness, set angle, etc.) of the elastic blade 61A are cleaned without applying unnecessary load to the drive source of the belt-shaped intermediate transfer body 70. It is appropriately selected from the viewpoint of ensuring safety. On the other hand, the various conditions of the metal scraper 61B are also selected as appropriate mainly from the viewpoint of ensuring cleanability. From the viewpoint of further improving the cleanability at the tip of the metal scraper 61B, for example, a belt shape It is preferable to perform an etching process on the leading edge contacting the surface of the intermediate transfer member 70. Further, the distance d between the elastic blade 61A and the metal scraper 61B may be appropriately selected depending on the shape of the cleaner case 61C, the set position, and the like. However, if the distance d between the two sheets is too close, the toner accumulates in the gaps between the two over time, and the cleaning performance may be deteriorated.

  Furthermore, in this embodiment, the elastic blade 61A and the metal scraper 61B are separated from the belt-shaped intermediate transfer body 70 portion corresponding to the roller 75 (backup roller) to the upstream side in the moving direction of the belt-shaped intermediate transfer body 70. It is disposed in the vicinity, and floating toner or dust adheres between the roller 75 and the belt-shaped intermediate transfer body 70, and a minute convex portion is formed on the surface portion of the belt-shaped intermediate transfer body 70 corresponding to the roller 75. Even so, the cleaning performance of the elastic blade 61A and the metal scraper 61B is not affected. However, the elastic blade 61A may be brought into contact with the belt-shaped intermediate transfer member 70 corresponding to the roller 75. In the present embodiment, the cleaning means 6A is disposed corresponding to the portion of the belt-shaped intermediate transfer body 70 located between the roller 75 and the roller 77 (a backup roller corresponding to the brush roller 61H). An elastic blade 61A and a metal scraper 61B are brought into contact with the belt-shaped intermediate transfer member 70.

  Then, during the cleaning cycle, the cleaning means 6A moves the swing arm 61D to a cleaning position (position closer to the belt-shaped intermediate transfer body 70 than the retract position) by a driving mechanism (not shown), so that the belt-shaped intermediate transfer body. While the elastic blade 61A and the tip of the metal scraper 61B are placed in contact with the surface at a predetermined contact pressure, the oscillating arm 61D is returned to the return spring 61G by a drive mechanism (not shown) during an imaging cycle other than the cleaning cycle. The elastic blade 61A and the tip of the metal scraper 61B are spaced apart from the surface of the belt-shaped intermediate transfer body 70 against the retracted position.

  As described above, by using a combination of the elastic blade 61A and the metal scraper 61B, a polymer toner containing a little residual monomer without requiring high rotational torque for the driving source of the belt-shaped intermediate transfer body 70 is used. In addition to improving the cleaning performance, it is possible to maintain stable cleaning performance even for minute convex portions on the belt-shaped intermediate transfer body 70. These effects were confirmed in Examples described later.

  A rubber elastic body is used as the material of the elastic blade, and urethane rubber, silicon rubber, fluorine rubber, chloropyrene rubber, butadiene rubber, and the like are known as the material. Of these, urethane rubber blades are other materials. It is particularly preferable in that it has excellent wear characteristics as compared with the rubber blades.

  It is preferable that at least one of the plurality of cleaning blades used in the cleaning means for the intermediate transfer member of the present invention is a non-deformable member. The non-deformable member means a member that does not cause elastic deformation due to contact with the intermediate transfer member. A metal scraper is preferably used as the non-deformable member.

  The metal scraper is a thin metal plate having a thickness of 0.01 to 2 mm, particularly preferably 0.02 to 0.5 mm. The metal thin plate is made of a flexible and rigid thin metal plate. Any metal material can be used, but a SUS300 series, SUS400 series stainless steel plate, aluminum plate, phosphor bronze plate, or the like is preferably used.

Preferred values of contact angle theta ₂ to the intermediate transfer member contact angle theta ₁ and metal scraper to the intermediate transfer member of the elastic blade, it is neither 5 to 35 °. The free length of the elastic blade and the metal scraper (the length of the leading portion not fixed to the holder 61F) is preferably 6 to 15 mm.

  The biting amount of the elastic blade and the metal scraper with respect to the intermediate transfer member is preferably set to 0.4 to 2.0 mm, more preferably 0.5 to 1.5 mm. This amount of biting means a load applied to the leading portion of the elastic blade or the leading portion of the metal scraper generated by the relative movement of the intermediate transfer member and the elastic blade or metal scraper. From the viewpoint of the intermediate transfer member, this load corresponds to the rubbing force received from the elastic blade or the metal scraper, and defining the range means that the intermediate transfer member needs to be scraped with an appropriate force. means. In addition, the amount of biting is that when the elastic blade or the metal scraper is brought into contact with the intermediate transfer member, the leading portion of the elastic blade or the leading portion of the metal scraper does not bend on the surface of the intermediate transfer member and enters the inside linearly. This is the length of biting into the interior.

  FIG. 3 is an arrangement diagram showing the positional relationship among the photosensitive member, the belt-shaped intermediate transfer member, and the primary transfer roller. The primary transfer rollers 5Y, 5M, 5C, and 5Bk are pressed from the back surface of the belt-like intermediate transfer member 70 as an intermediate transfer member to the photosensitive members 1Y, 1M, 1C, and 1Bk, as shown in the layout diagram of FIG. The primary transfer rollers 5Y, 5M, 5C, and 5Bk are located downstream of the contact point between the belt-like intermediate transfer member 70 as an intermediate transfer member when not pressed and the photosensitive members 1Y, 1M, 1C, and 1Bk in the rotational direction of the photosensitive member. Are arranged and pressed to the photoreceptors 1Y, 1M, 1C, and 1Bk. At this time, the belt-like intermediate transfer member 70 as an intermediate transfer member is bent along the outer periphery of each of the photosensitive members 1Y, 1M, 1C, and 1Bk, and is most downstream in the contact area between the photosensitive member and the belt-like intermediate transfer member 70. The primary transfer rollers 5Y, 5M, 5C, and 5Bk are arranged.

  FIG. 4 is an arrangement diagram showing the positional relationship among the backup roller, the belt-shaped intermediate transfer member, and the secondary transfer roller. As shown in the layout diagram of FIG. 4, the secondary transfer roller 5 </ b> A is more than the contact center portion between the belt-like intermediate transfer body 70 and the backup roller 74 as an intermediate transfer body when not pressed by the secondary transfer roller 5 </ b> A. It is desirable that the backup roller 74 is disposed upstream of the rotation direction.

  As the intermediate transfer member, a polymer film such as polyimide, polycarbonate, PVdF, or a synthetic rubber such as silicone rubber or fluororubber added with a conductive filler such as carbon black is used. Either a belt shape may be used, but a belt shape is preferable from the viewpoint of freedom in device design.

  The surface of the intermediate transfer member is preferably appropriately roughened. By setting the 10-point surface roughness Rz of the intermediate transfer member to 0.5 to 2 μm, the surface energy reducing agent supplied to the photosensitive member is taken into the surface of the intermediate transfer member and the toner adhesion on the intermediate transfer member is reduced. It becomes easy to improve the transfer rate of the secondary transfer of toner from the intermediate transfer member to the recording material. In this case, the effect tends to be greater when the ten-point surface roughness Rz of the intermediate transfer member is larger than the ten-point surface roughness Rz of the photosensitive member.

  On the other hand, the photosensitive member cleaning means is basically the same as the intermediate transfer member cleaning means shown in FIG. 2 except for the metal scraper. The cleaning means is used as a cleaning means such as 6Y, 6M, 6C, 6Bk in FIG.

Next, embodiments of the present invention will be specifically described. However, the configuration of the present invention is not limited to this.
(Development of developer)
(Manufacture of toner Bk (black))
0.90 kg of sodium n-dodecyl sulfate and 10.0 liters of pure water were added and dissolved by stirring. To this solution, 1.20 kg of Legal 330R (Cabot Black Carbon Black) was gradually added and stirred well for 1 hour, followed by continuous dispersion for 20 hours using a sand grinder (medium disperser). This is referred to as “colorant dispersion 1”.

  A solution composed of 0.055 kg of sodium dodecylbenzenesulfonate and 4.0 liters of ion-exchanged water is referred to as “anionic surfactant solution A”.

  A solution composed of 0.014 kg of nonylphenol polyethylene oxide 10 mol adduct and 4.0 liters of ion-exchanged water is referred to as “nonionic surfactant solution B”.

  A solution obtained by dissolving 223.8 g of potassium persulfate in 12.0 liters of ion-exchanged water is referred to as “initiator solution C”.

  A GL (glass lining) reaction kettle with a volume of 100 liters equipped with a temperature sensor, a condenser tube, and a nitrogen introducing device was added to a WAX emulsion (a polypropylene emulsion having a number average molecular weight of 3000: number average primary particle size = 120 nm / solid content concentration = 29. 9%) 3.41 kg, the total amount of “anionic surfactant solution A” and the total amount of “nonionic surfactant solution B” were added, and stirring was started. Subsequently, 44.0 liters of ion exchange water was added.

  Heating was started and when the liquid temperature reached 75 ° C., the entire amount of “Initiator Solution C” was added dropwise. Thereafter, while controlling the liquid temperature at 75 ° C. ± 1 ° C., 12.1 kg of styrene, 2.88 kg of n-butyl acrylate, 1.04 kg of methacrylic acid, and 548 g of t-dodecyl mercaptan were added dropwise. After completion of the dropping, the liquid temperature was raised to 86 ° C. ± 1 ° C., and the mixture was heated and stirred for 5 hours to carry out emulsion polymerization. Next, the liquid temperature was cooled to 40 ° C. or less to stop the polymerization reaction, and then the residual monomer was distilled off under reduced pressure (1.33 kPa), followed by filtration through a pole filter to obtain a latex. This is designated as “Latex-A”.

  The glass transition temperature of the resin particles in Latex-A was 57 ° C., the softening point was 121 ° C., the molecular weight distribution was weight average molecular weight = 17,000, and the weight average particle size was 120 nm.

  A solution prepared by dissolving 0.055 kg of sodium dodecylbenzenesulfonate in 4.0 liters of ion-exchanged pure water is referred to as “anionic surfactant solution D”.

  Further, a solution obtained by dissolving 0.014 kg of nonylphenol polyethylene oxide 10 mol adduct in 4.0 liters of ion-exchanged water is referred to as “nonionic surfactant solution E”.

  A solution obtained by dissolving 200.7 g of potassium persulfate (manufactured by Kanto Chemical Co., Ltd.) in 12.0 liters of ion-exchanged water is referred to as “initiator solution F”.

  A WAX emulsion (a polypropylene emulsion with a number average molecular weight of 3000: number average primary particle size = 120 nm / solid content concentration of 29.9%) was added to a 100 liter GL reaction kettle equipped with a temperature sensor, a cooling pipe, a nitrogen introducing device and a comb baffle. 3.41 kg, the total amount of “anionic surfactant solution D” and the total amount of “nonionic surfactant solution E” were added, and stirring was started.

  Next, 44.0 liters of ion exchange water was added. Heating was started, and when the liquid temperature reached 70 ° C., “initiator solution F” was added. Then, a solution prepared by previously mixing 11.0 kg of styrene, 4.00 kg of n-butyl acrylate, 1.04 kg of methacrylic acid, and 9.02 g of t-dodecyl mercaptan was dropped. After completion of the dropping, the liquid temperature was controlled at 80 ° C. ± 2 ° C., and the mixture was heated and stirred for 5 hours to carry out emulsion polymerization. Next, the liquid temperature was cooled to 40 ° C. or less to stop the polymerization reaction, and then the residual monomer was distilled off under reduced pressure (1.33 kPa), followed by filtration through a pole filter to obtain a latex. This is designated as “Latex-B”.

  The glass transition temperature of the resin particles in Latex-B was 58 ° C., the softening point was 132 ° C., the molecular weight distribution was weight average molecular weight = 245,000, and the weight average particle size was 110 nm.

  A solution obtained by dissolving 5.36 kg of sodium chloride as a salting-out agent in 20.0 liters of ion-exchanged water is referred to as “sodium chloride solution G”.

  A solution obtained by dissolving 1.00 g of a fluorine-based nonionic surfactant in 1.00 liter of ion-exchanged water is referred to as “nonionic surfactant solution H”.

  In a 100 liter SUS reaction kettle equipped with a temperature sensor, a cooling pipe, a nitrogen introduction device, a particle size and shape monitoring device, latex-A = 20.0 kg, latex-B = 5.2 kg, and a colorant prepared above. Dispersion 1 = 0.4 kg and ion-exchanged water 20.0 kg were added and stirred. Next, the mixture was heated to 40 ° C., and sodium chloride solution G, 6.00 kg of isopropanol (manufactured by Kanto Chemical Co., Inc.) and nonionic surfactant solution H were added in this order. Then, after standing for 10 minutes, temperature increase was started, the temperature was raised to 85 ° C. in 60 minutes, and the mixture was heated and stirred at 85 ± 2 ° C. for 0.5 to 3 hours while being salted out / fused. Diameter growth. Next, 2.1 liters of pure water was added to stop the particle size growth, and a fused particle dispersion was prepared (salting out / fusing stage).

  In a 5-liter reaction vessel equipped with a temperature sensor, a cooling pipe, a particle size and shape monitoring device, 5.0 kg of the fused particle dispersion prepared above was placed, and the liquid temperature was 85 ° C. ± 2 ° C. The shape was controlled by heating and stirring for 5 to 15 hours (shape control step). Then, it cooled to 40 degrees C or less and stopped stirring. Next, using a centrifugal separator, classification is performed in the liquid by a centrifugal sedimentation method, followed by filtration through a sieve having an opening of 45 μm, and this filtrate is used as an association liquid. Subsequently, wet cake-like non-spherical particles were collected by filtration from the associating solution using a Nutsche. Thereafter, it was washed with ion exchange water. The non-spherical particles were dried at a suction air temperature of 60 ° C. using a flash jet dryer and then dried at a temperature of 60 ° C. using a fluidized bed dryer. To 100 parts by mass of the obtained colored particles, 1 part by mass of silica fine particles was externally added and mixed with a Henschel mixer to obtain a toner 1Bk by an emulsion polymerization association method. The residual monomer amount of toner 1Bk was 120 ppm.

In the monitoring of the liquid temperature and reaction time conditions during the emulsion polymerization of the latex A and latex B, the residual monomer distillation conditions (reduced pressure conditions), the salting-out / fusion stage and the shape control process, By controlling the heating time, the amount of residual monomer, the shape factor, and the proportion of toner particles having no corners are controlled, and the particle size and particle size distribution are arbitrarily adjusted by submerging, and the shape characteristics shown in Table 1 In addition, toners 1Bk to 9Bk composed of toner particles having particle size distribution characteristics and the like were obtained.
(Manufacture of toner Y (yellow))
In the production of the toners 1Bk to 9Bk, C.I. I. Toners 1Y to 9Y were obtained in the same manner except that CI Pigment Yellow 185 was used. Table 1 shows the amount of residual monomers, the shape factor, the proportion of toner particles without corners, the particle size, the particle size distribution, and the like of toners 1Y to 9Y.
(Manufacture of toner M (magenta))
In the production of the toners 1Bk to 9Bk, C.I. I. Toners 1M to 9M were obtained in the same manner except that CI Pigment Red 122 was used. Table 1 shows the amount of residual monomers, the shape factor, the proportion of toner particles having no corners, the particle size and the particle size distribution of toners 1M to 9M.
(Manufacture of toner C (cyan))
In the production of the toners 1Bk to 9Bk, C.I. I. Toners 1C to 9C were obtained in the same manner except that CI Pigment Blue 15: 3 was used. Table 1 shows the amount of residual monomers, the shape factor, the ratio of toner particles having no corners, the particle size, the particle size distribution, and the like of toners 1C to 9C.

The residual monomer in the toner of the present invention was quantified using the headspace gas chromatograph measurement method described above.
[Manufacture of developer]
For evaluation, 10 parts by weight of each of toners 1Bk to 9Bk, toners 1Y to 9Y, toners 1M to 9M, and toners 1C to 9C are mixed with 100 parts by weight of a 45 μm ferrite carrier coated with a styrene-methacrylate copolymer. Developers 1Bk to 9Bk, Developers 1Y to 9Y, Developers 1M to 9M, Developers 1C to 9C were produced, and Developer groups 1 to 9 shown in Table 1 were produced.

[Production of photoconductor]
Photoconductors used in the examples were produced as follows (the photoconductors in each example were produced in a total of four or more because each image unit uses the same type of photoconductor).

Preparation of Photoreceptor The following intermediate layer coating solution was prepared and applied onto a washed cylindrical aluminum substrate by a dip coating method to form an intermediate layer having a dry film thickness of 0.3 μm.

<Intermediate layer (UCL) coating solution>
Polyamide resin (Amilan CM-8000: manufactured by Toray Industries, Inc.) 60 g
1600 ml of methanol
The following coating solution components were mixed and dispersed for 10 hours using a sand mill to prepare a charge generation layer coating solution. This coating solution was applied by a dip coating method to form a charge generation layer having a dry film thickness of 0.2 μm on the intermediate layer.

<Charge generation layer (CGL) coating solution>
Y-type titanyl phthalocyanine (Maximum peak angle of X-ray diffraction by Cu-Kα characteristic X-ray is 27.3 at 2θ) 60 g
700 g of silicone resin solution (KR5240, 15% xylene-butanol solution: manufactured by Shin-Etsu Chemical Co., Ltd.)
2-butanone 2000ml
The following coating solution components were mixed and dissolved to prepare a charge transport layer coating solution. This coating solution was applied onto the charge generation layer by a dip coating method to form a charge transport layer having a thickness of 20 μm.

<Charge transport layer (CTL) coating solution>
Charge transport material (4-methoxy-4 '-(4-methyl-α-phenylstyryl) triphenylamine) 200 g
Bisphenol Z-type polycarbonate (Iupilon Z300: manufactured by Mitsubishi Gas Chemical Company) 300g
Hindered amine (Sanol LS2626: Sankyosha) 3g
1,2-dichloroethane 2000ml
<Surface protective layer>
Charge transport material (4-methoxy-4 '-(4-methyl-α-phenylstyryl) triphenylamine) 200 g
Bisphenol Z-type polycarbonate (Iupilon Z300: manufactured by Mitsubishi Gas Chemical Company) 300g
Hindered amine (Sanol LS2626: Sankyosha) 3g
100 g of polytetrafluoroethylene resin particles (average particle size 0.5 μm)
1-butanol 50g
Were mixed and dissolved to prepare a surface protective layer coating solution. This coating solution was applied onto the charge transport layer by a dip coating method, followed by heat curing at 100 ° C. for 40 minutes to form a surface protective layer having a dry film thickness of 4 μm, thereby preparing a photoreceptor. The surface contact angle of the photoreceptor with respect to water was 106 °.

<Evaluation>
In each of the image forming units, the four photosensitive members and Y (yellow), M (magenta), C (cyan), and Bk (black) for each developer group (toner group) shown in Table 1 are used. 4 sets of developing means containing the developer (toner) of the above are combined, and these photoconductors and developing means are mounted on a digital copying machine having the intermediate transfer member shown in FIGS. In addition, 10,000 A4 images having solid (solid) image portions, character image portions, and halftone images of Y, M, and C were printed at room temperature and normal humidity (20 ° C., 50% RH) and evaluated. Evaluation items, evaluation methods, and evaluation criteria are described below.

Character dust A character image was formed, and toner dust around the characters was observed visually and with a 20-fold magnifier, and evaluated according to the following criteria.

A: Toner dust around the characters is not observed even with loupe observation (good)
○: Cannot be visually discerned, but toner dust around the characters is observed with a loupe (no problem in practice)
X: Toner dust around the character is visually observed, and the sharpness of the character is inferior (practically problematic)
Transfer missing A halftone image having a density of 0.4 was formed on both sides of a transfer paper (basis weight 200 g / m ² ), and the occurrence of white spots due to transfer missing was visually evaluated.

◎◎: No transfer at all (very good)
A: 1 to 2 transfer omissions exist only on the back surface per 100 images, but it cannot be distinguished without staring (good)
○: Although there are 1 to 4 transfer omissions per 50 images, it cannot be determined without staring (no problem in practical use)
×: 5 or more clear transfer omissions exist for 50 images regardless of the front and back sides (practical problem)
Cleanability of intermediate transfer member A: No toner aggregation on the intermediate transfer member, good cleaning, and no image unevenness (good)
○: Slight aggregation of toner or the like occurs on the intermediate transfer member, but cleaning is good and image unevenness does not occur (no problem in practical use)
X: Aggregation of toner or the like occurs on the intermediate transfer member, toner slips out, and image unevenness occurs. (There are practical problems)
Image Density The image density was measured by using a densitometer “RD-918” (manufactured by Macbeth) for the solid part of each color and measuring the relative reflection density with zero recording paper.

A: Each density of the solid (solid) image portion of Bk and Y, M, C is 1.2 or more (good)
○: Each density of the solid (solid) image portion of Bk and Y, M, C is 0.8 or more (no problem in practical use)
X: Each density of the solid (solid) image part of Bk and Y, M, and C is less than 0.8 (practical problem)
(Sharpness)
The sharpness of the image was evaluated by squeezing the characters in both low temperature and low humidity (10 ° C., 20% RH) and high temperature, high humidity (30 ° C., 80% RH) environments. 3-point and 5-point character images were formed and evaluated according to the following criteria.

◎: 3 points and 5 points are clear and easily readable ○: 3 points are partially unreadable 5 points are clear and easily readable ×: 3 points are almost unreadable Part or all of the image is unreadable Process conditions for a digital copying machine having an intermediate transfer body Image forming line speed L / S: 180 mm / s
Charging condition of the photoconductor (40 mmφ): The potential of the non-image part is detected by a potential sensor and can be feedback controlled. The controllable range is −500 V to −900 V, and the surface of the photoconductor when fully exposed The potential was in the range of −50 to 0V.

Image exposure light: Semiconductor laser (wavelength: 780 nm)
Intermediate transfer member: A seamless belt-like intermediate transfer member 70, a semiconductive resin belt having a volume resistivity of 1 × 10 ⁸ Ω · cm and Rz of 0.9 μm was used.

Primary transfer conditions Primary transfer roller (5Y, 5M, 5C, 5Bk (each 6.05 mmφ) in FIG. 1): Configuration in which elastic rubber is attached to the core: Surface specific resistance 1 × 10 ⁶ Ω, transfer voltage applied Secondary transfer Conditions A belt-like intermediate transfer member 70 as an intermediate transfer member and a backup roller 74 and a secondary transfer roller 5A are disposed so as to sandwich the belt-like intermediate transfer member 70, and the resistance value of the backup roller 74 is 1 × 10 ⁶ Ω. The secondary transfer roller has a resistance value of 1 × 10 ⁶ Ω and constant current control (about 80 μA).

  Fixing is a thermal fixing method using a fixing roller in which a heater is disposed inside the roller.

  The distance Y on the intermediate transfer member from the first contact point between the intermediate transfer member and the photosensitive member to the first contact point with the next photosensitive member was set to 95 mm.

  The outer peripheral length (circumferential length) of the drive roller 71, the guide rollers 72 and 73 and the backup roller 74 for secondary transfer is 31.67 mm (= 95 mm / 3), and the outer peripheral length of the tension roller 76 is 23. .75 mm (= 95 mm / 4).

  The outer peripheral length of the primary transfer roller was 19 mm (= 95 mm / 5).

Cleaning Condition of Photoreceptor Cleaning Blade: A urethane rubber blade (free length: 8 mm) having a JISA hardness of 65 degrees and a rebound resilience of 60 was contacted by a counter method in the rotation direction of the photoreceptor with a contact load of 18 N / m.

Cleaning Condition for Intermediate Transfer Member The cleaning means shown in FIG. 2 was used as the cleaning means 6A.

  Elastic blade 61A: Urethane rubber having a rebound resilience of 35 at a rubber hardness of 75 ° and 23 ° C. was used. The elastic blade 61A has a thickness of 2 mm, a free length of 10 mm, is supported by a support member (swinging arm 61D + holder 61F), and makes an angle with the belt-shaped intermediate transfer body 70 in contact with the intermediate transfer body moving direction in a counter manner. (Angle 16.5 °). The amount of biting into the belt-shaped intermediate transfer member 70 at the tip of the elastic blade 61A was 1.25 mm.

  Metal scraper 61B: SUS304 whose tip was etched was used. The metal scraper 561B has a thickness of 0.15 mm and a free length of 10 mm. The metal scraper 561B is supported by a support member (swinging arm 61D + holder 61f), and an angle formed with the belt-shaped intermediate transfer body 70 is counter-type in the direction of movement of the intermediate transfer body. (Angle 16.5 °). The amount of biting into the belt-shaped intermediate transfer body 70 at the tip of the metal scraper 61B was 1.00 mm. The distance d between the upstream elastic blade 61A and the downstream metal scraper 61B was set to 2 mm.

  The results are shown in Table 2.

From Table 2 above, a developer group satisfying the requirements of the present invention, that is, a developer group in which the amount of residual monomer of each colored toner used in the developing means of each image forming unit is 300 ppm or less (No. 1, 3 No. 9) has achieved good evaluations exceeding the practical range in terms of character dust, transfer omission, intermediate transfer member cleaning property, image density, and sharpness, whereas the developer group (No. 2) outside the present invention. However, transfer omission, cleaning of the intermediate transfer member, image density, and sharpness are deteriorated. Further, among the developer groups satisfying the requirements of the present invention, each colored toner has 65% by number or more of toner particles having a shape factor in the range of 1.2 to 1.6, and is next to the most frequent class. Developer group (No.) satisfying the condition that the sum (M) of the relative frequency (m ₂ ) of the toner particles contained in the high class is 70% or more and containing 50% by number or more of toner particles having no corners .1) has a remarkable improvement effect.

Example 2 (Change of intermediate transfer member cleaning means)
Evaluation of developer groups 7, 8, and 9 in Example 1 was performed under the condition that the metal scraper of the cleaning means for the intermediate transfer member was removed. Evaluation items, evaluation methods, and evaluation criteria were the same as in Example 1. The evaluation results are shown in Table 3.

  From the results in Table 3, it is found that all the evaluation results are lower than those in Example 1. In particular, the deterioration of the cleaning property of the intermediate transfer member and the sharpness deterioration associated therewith are large. That is, under the condition that the metal scraper is removed from the cleaning means for the intermediate transfer member, the cleaning property of the intermediate transfer member is deteriorated even when a developer group within the scope of the present invention is used, and sufficient image performance cannot be obtained. Found.

1 is a cross-sectional configuration diagram of a color image forming apparatus showing an embodiment of the present invention. 2 is an example of an intermediate transfer member cleaning unit. FIG. 3 is a layout diagram illustrating a positional relationship among a photosensitive member, a belt-shaped intermediate transfer member, and a primary transfer roller. FIG. 6 is a layout diagram showing a positional relationship among a backup roller, a belt-shaped intermediate transfer member, and a secondary transfer roller. FIG. 6 is a diagram illustrating toner particles having no corners.

Explanation of symbols

1Y, 1M, 1C, 1Bk photoconductor 2Y, 2M, 2C, 2Bk charging means 3Y, 3M, 3C, 3Bk exposure means 4Y, 4M, 4C, 4Bk developing means 5A secondary transfer roller (secondary transfer means)
5Y, 5M, 5C, 5Bk Primary transfer roller (primary transfer means)
6Y, 6M, 6C, 6Bk Photoconductor cleaning means 7 Belt-shaped intermediate transfer body unit 10Y, 10M, 10C, 10Bk Image forming unit (image forming unit)
6A Cleaning means for intermediate transfer member 70 Belt-shaped intermediate transfer member

Claims (17)

A plurality of image forming units having at least an electrophotographic photosensitive member, a charging unit, an exposing unit, a developing unit, a transferring unit, and a cleaning unit are arranged and electrophotographic using a toner whose coloring is changed for each of the plurality of image forming units. Each colored toner image formed on the photoconductor is sequentially superimposed and transferred onto the intermediate transfer member to form a color toner image, and the color toner image is collectively retransferred onto the recording material and retransferred. In the image forming apparatus for fixing the color toner image to form a color image, the residual monomer amount of each colored toner used in the developing means of the plurality of image forming units is 300 ppm or less and remains on the intermediate transfer member. An image forming apparatus comprising an intermediate transfer member cleaning unit that removes the transferred residual toner with a plurality of cleaning blades. A plurality of image forming units having at least an electrophotographic photosensitive member, a charging unit, an exposing unit, a developing unit, a transferring unit, and a cleaning unit are arranged and electrophotographic using a toner whose coloring is changed for each of the plurality of image forming units. Each colored toner image formed on the photoconductor is sequentially superimposed and transferred onto the intermediate transfer member to form a color toner image, and the color toner image is collectively retransferred onto the recording material and retransferred. In the image forming apparatus for fixing a color toner image to form a color image, each colored toner used in the developing means of the plurality of image forming units has toner particles having a shape factor in the range of 1.2 to 1.6. Intermediate transfer in which 65% by weight or more of the residual monomer amount is 300 ppm or less and residual transfer toner remaining on the intermediate transfer member is removed by a plurality of cleaning blades. Image forming apparatus characterized by having an iodine cleaning means. A plurality of image forming units having at least an electrophotographic photosensitive member, a charging unit, an exposing unit, a developing unit, a transferring unit, and a cleaning unit are arranged and electrophotographic using a toner whose coloring is changed for each of the plurality of image forming units. Each colored toner image formed on the photoconductor is sequentially superimposed and transferred onto the intermediate transfer member to form a color toner image, and the color toner image is collectively retransferred onto the recording material and retransferred. In the image forming apparatus for fixing a color toner image to form a color image, each colored toner used in the developing means of the plurality of image forming units is natural when the particle diameter of the toner particles is D (μm). The logarithm lnD is taken on the horizontal axis, and the relative frequency of the toner particles contained in the most frequent class in the histogram showing the number-based particle size distribution in which the horizontal axis is divided into a plurality of classes at intervals of 0.23 ( _1), the sum (M) is not less than 70% and a residual monomer content of the relative frequency (m ₂₎ of the toner particles contained in the following frequent the rank of the most frequent class is at 300ppm or less, wherein An image forming apparatus comprising an intermediate transfer member cleaning unit that removes residual transfer toner remaining on an intermediate transfer member with a plurality of cleaning blades. A plurality of image forming units having at least an electrophotographic photosensitive member, a charging unit, an exposing unit, a developing unit, a transferring unit, and a cleaning unit are arranged and electrophotographic using a toner whose coloring is changed for each of the plurality of image forming units. Each colored toner image formed on the photoconductor is sequentially superimposed and transferred onto the intermediate transfer member to form a color toner image, and the color toner image is collectively retransferred onto the recording material and retransferred. In the image forming apparatus for fixing a color toner image to form a color image, each colored toner used in the developing means of the plurality of image forming units contains 50% by number or more of toner particles having no corners and a residual monomer An intermediate transfer member cleaning unit that has an amount of 300 ppm or less and removes transfer residual toner remaining on the intermediate transfer member with a plurality of cleaning blades. Image forming apparatus characterized by. A plurality of image forming units are four image forming units, an image forming unit having black toner, an image forming unit having yellow toner, an image forming unit having magenta toner, and an image forming having cyan toner The image forming apparatus according to claim 1, comprising a unit. 6. The image forming apparatus according to claim 1, wherein the number average particle size of the black toner is 3.0 to 8.0 [mu] m. The image forming apparatus according to claim 4, wherein the black toner is a polymerized toner. The image forming apparatus according to claim 4, wherein the black toner, yellow toner, magenta toner, and cyan toner are polymerized toners. The image forming apparatus according to claim 1, wherein at least one of the plurality of cleaning blades is a non-deformable member. The image forming apparatus according to claim 9, wherein the non-deformable member is formed of a metallic scraper. The image forming apparatus according to claim 1, wherein at least one of the plurality of cleaning blades is an elastic blade. The image forming apparatus according to claim 11, wherein the elastic blade is a urethane rubber blade. The image forming apparatus according to claim 1, wherein a contact angle of water on the surface of the electrophotographic photosensitive member is 90 ° or more. The image forming apparatus according to claim 1, wherein a surface layer of the electrophotographic photosensitive member contains fluororesin particles. The image forming apparatus according to claim 1, wherein the surface layer of the electrophotographic photosensitive member contains an antioxidant. The image forming apparatus according to claim 1, wherein the intermediate transfer member is a belt-shaped intermediate transfer member. An image forming method, comprising: forming an electrophotographic image using the image forming apparatus according to claim 1.

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