JP2008102171A - Electrophotographic photoreceptor and electrophotographic image forming apparatus, electrophotographic image forming method and process cartridge using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic photoreceptor excellent in transferability and cleaning characteristics, less liable to wear and capable of supplying a high-quality image, an electrophotographic image forming method and an electrophotographic image forming apparatus using the same, and a process cartridge for use in the apparatus. <P>SOLUTION: The electrophotographic photoreceptor has a photosensitive layer on a support, wherein a surface layer of the electrophotographic photoreceptor contains fine particles having lubricity, and when the surface layer is continuously scratched with a needle, S value determined by variations (X<SB>1</SB>-X<SB>24</SB>) of resistance (mN) generated between the surface layer and needle satisfies the formula: 1.0≤S≤10.0, wherein X<SB>1</SB>is a maximum value of resistance in 0-5 s; X<SB>2</SB>is a minimum value of resistance in 0-5 s; ... X<SB>23</SB>is a maximum value of resistance in 55-60 s; and X<SB>24</SB>is a minimum value of resistance in 55-60 s, wherein the unit of the Xn is mN. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrophotographic photosensitive member, an electrophotographic image forming apparatus using the photosensitive member, and a process cartridge used in the apparatus.

  There are various degradation factors in the electrophotographic process. For example, NOx generated from the strip electrode, separation electrode, chemical (oxidative decomposition) degradation due to ozone, electrical degradation due to repeated charging, slow charging, light degradation, for example, image degradation, light degradation due to static elimination light, and other transfer processes There is light degradation due to light irradiation in a cleaning process or the like.

  Further, for example, there is deterioration due to contact charging, friction due to a cleaning blade, transfer, separation claw, etc., pressure deterioration (abrasion, scratches), etc., and further, there is combined deterioration due to the above factors.

  Due to the above deterioration factors, the photoreceptor is deteriorated, and a good image cannot be obtained due to, for example, an increase in surface energy due to abrasion, scratches, oxidation, adhesion or burying of toner or an external additive, etc. Blur, low density, white streaks due to scratches, white-out images due to deposits, voids, transfer efficiency reduction), and the life of the photoreceptor is reduced.

  Conventionally, by reducing the coefficient of friction and surface energy of the photoreceptor surface, transferability and cleaning properties are improved, and unnecessary toner adhesion is prevented, and an image free of background stains can be obtained. Are known. Further, a photoconductor with a small surface friction coefficient can extend the life of the photoconductor by reducing the amount of surface wear due to rubbing such as cleaning.

  Further, it is known that by reducing the coefficient of friction on the surface of the photoconductor, the transfer efficiency when the toner image formed on the photoconductor is transferred to the transfer target is improved. That is, it is possible to suppress the omission of thin line images, reduce the amount of residual toner on the photoconductor after transfer, and reduce the amount of waste toner. Furthermore, in the case of the polymerized toner, the cleaning property is also excellent.

  As such a method for lubricating the photoreceptor surface, an image forming apparatus having a mechanism for supplying a lubricant to the photoreceptor surface has been proposed and put into practical use. However, there is a problem that an increase in size and complexity of the apparatus cannot be avoided, and problems such as cost increase and deterioration in maintainability occur.

  On the other hand, adding a lubricant to the surface layer of the photoreceptor has been proposed as a different method for lubricating the surface of the photoreceptor.

  Lubricants include fluorine atom-containing resins such as polytetrafluoroethylene (hereinafter referred to as fluororesins), spherical acrylic resins, polyethylene resin powder particles, metal oxide powder particles such as silicon oxide and aluminum oxide, silicone oil, etc. Lubricating liquids are known. Such lubricating fine particles are dispersed or mixed in a binder resin and formed, for example, as a surface layer or a protective layer of a photoreceptor (for example, Patent Documents 1 to 3).

  However, such lubricating fine particles have low compatibility with the binder solution, have a strong tendency to agglomerate, are difficult to uniformly disperse, and cause problems such as non-uniformly agglomerated paint film portions resulting in image defects and poor cleaning. There is a problem that stable performance cannot be obtained.

However, due to colorization, high resolution, and low-temperature fixing of image formation in recent years, due to toner atomization, spheroidization, low-temperature softening point, etc. The transfer rate is reduced, cleaning is likely to be poor, and the electrophotographic image is deteriorated due to repetition, and the transfer uniformity or the dispersion uniformity of the lubricating particles in the photoreceptor has been an important problem.
JP-A 63-30850 Japanese Patent Application Laid-Open No. 64-35448 JP-A-2-189551

  The present invention is excellent in transferability and cleaning characteristics, gives a clear copy image in all environments, has good scratch resistance and filming resistance, is low in wear even when making a large amount of copies and prints, and has high quality. An object of the present invention is to provide an electrophotographic photosensitive member capable of stably supplying an image, an electrophotographic image forming method using the electrophotographic photosensitive member, an electrophotographic image forming apparatus, and a process cartridge used in the apparatus.

  As a result of diligent efforts to solve the above problems, the inventors of the present invention need to form a highly uniform surface for transferability in a system in which lubricating particles are dispersed in a photoreceptor. As a result, the inventors have found that the above problems can be solved by configuring the surface physical properties as follows, and the present invention has been completed.

  The object of the present invention is achieved by the following means.

  1. In an electrophotographic photosensitive member having a photosensitive layer on a support, when the surface layer of the electrophotographic photosensitive member contains fine particles having lubricity and the surface layer is continuously scratched with a needle, the surface layer When the fluctuation value of the resistance value (mN) generated between the needle and the needle is expressed by the following formula (1), the physical properties of the surface layer are configured to satisfy the following formula (2). An electrophotographic photoreceptor.

Formula (1)
T = X ₁ ² + X ₂ ² ... + X ₂₄ ²
_{M = (X 1 + X 2} ····· + X 24) 2/24
N = [{(X ₁ + X ₃ ... + X ₂₃ ) ² + (X ₂ + X ₄ ... + X ₂₄ ) ² } / 12] −M
E = (TMN) / 22
X ₁ : Maximum resistance value for 0 to 5 seconds X ₂ : Minimum resistance value for 0 to 5 seconds X ₃ : Maximum resistance value for 5 to 10 seconds X ₄ : Resistance value for 5 to 10 seconds minimum value X _5: the maximum of the resistance value of 5 to 15 seconds X _6: minimum value of the resistance values of 5 to 15 seconds X _7: maximum resistance of 15 to 20 seconds X _8: 15-20 seconds resistance Minimum value
・
・
X ₂₃ : Maximum value of resistance value for 55 to 60 seconds X ₂₄ : Minimum value of resistance value for 55 to 60 seconds (The unit of Xn is mN)
Formula (2)
1.0 ≦ S ≦ 10.0
However,
S = 10 log {(ME) / 24E}
2. In an electrophotographic photosensitive member having a photosensitive layer on a support, when the surface layer of the electrophotographic photosensitive member contains fine particles having lubricity and the surface layer is continuously scratched with a needle, the surface layer An electrophotography characterized in that the physical properties of the surface layer satisfy the following formula (3) when the fluctuation value of the resistance value generated between the needle and the needle is represented by the following formula (1): Photoconductor.

Formula (1)
T = X ₁ ² + X ₂ ² ... + X ₂₄ ²
_{M = (X 1 + X 2} ····· + X 24) 2/24
N = [{(X ₁ + X ₃ ... + X ₂₃ ) ² + (X ₂ + X ₄ ... + X ₂₄ ) ² } / 12] −M
E = (TMN) / 22
X ₁ : Maximum resistance value for 0 to 5 seconds X ₂ : Minimum resistance value for 0 to 5 seconds X ₃ : Maximum resistance value for 5 to 10 seconds X ₄ : Resistance value for 5 to 10 seconds minimum value X _5: the maximum of the resistance value of 5 to 15 seconds X _6: minimum value of the resistance values of 5 to 15 seconds X _7: maximum resistance of 15 to 20 seconds X _8: 15-20 seconds resistance Minimum value
・
・
X ₂₃ : Maximum value of resistance value for 55 to 60 seconds X ₂₄ : Minimum value of resistance value for 55 to 60 seconds (The unit of Xn is mN)
Formula (3)
20.0 ≦ K ≦ 45.0
However, K is represented by the following formula.

K = 10 log {(ME) / 24}
3. 3. The electrophotographic photosensitive member according to item 1 or 2, wherein the proportion of the fine particles in the surface layer is 5% by mass to 30% by mass.

  4). 4. The electrophotographic photosensitive member according to any one of items 1 to 3, wherein an average primary particle size of the fine particles is in a range of 0.01 to 0.3 μm.

  5. 5. The electrophotographic photosensitive member according to any one of 1 to 4, wherein the fine particles contain a silicon atom.

  6). 5. The electrophotographic photosensitive member according to any one of 1 to 4, wherein the fine particles contain a fluorine atom.

  7. 7. The electrophotographic photosensitive material as described in any one of 1 to 6 above, wherein the photosensitive layer comprises a layer containing at least a charge generating material and a charge transport material, and a protective layer laminated thereon. body.

  8). 8. An electrophotographic image forming apparatus having a photosensitive member and at least charging, image exposing, developing, and transferring means, wherein the photosensitive member is the electrophotographic photosensitive member according to any one of 1 to 7. An electrophotographic image forming apparatus.

  9. In the electrophotographic image forming method for obtaining an image by at least charging, image exposure, development and transfer on a photoconductor, the photoconductor is the electrophotographic photoconductor described in any one of 1 to 7 above. An electrophotographic image forming method.

  10. A process cartridge for use in an electrophotographic image forming apparatus having a photosensitive member and at least charging, image exposure, development, and transfer means, the electrophotographic photosensitive member according to any one of 1 to 7 above, and charging And an image exposure device, a developing device, a cleaning device, and a slow current device, and is designed to be freely inserted into and removed from the electrophotographic image forming apparatus. cartridge.

  According to the present invention, even when repeated many times, wear and scratches are suppressed, a low surface friction coefficient is maintained, a high transfer rate is good, electrophotographic characteristics are good, and long-term stable image formation and cleaning are performed. Therefore, it is possible to provide an inexpensive and highly durable electrophotographic photosensitive member that can achieve high image quality and high reliability. In addition, an image forming apparatus using the electrophotographic photosensitive member and a process cartridge for the image forming apparatus can be provided.

  As a result of repeated studies to solve the above problems, the present inventors have found that the above-mentioned problems can be solved by configuring the surface layer of the photoreceptor as follows.

  That is, in the electrophotographic photoreceptor according to the present invention (hereinafter sometimes simply referred to as a photoreceptor), the surface layer of the photoreceptor contains fine particles having lubricity, and the surface layer is continuously formed with a needle. When the fluctuating value of the resistance value (mN) generated between the surface layer and the needle when scratched is expressed by the above equation (1), the physical properties of the surface layer satisfy the above equation (2). Or it is constituted so as to satisfy the above-mentioned formula (3).

  The resistance value generated between the surface layer and the needle when the surface layer of the photoreceptor is continuously scratched with the needle will be described with reference to FIG. As shown in FIG. 5, the photosensitive drum is installed parallel to the central axis and fixed. A needle is set up at a degree of penetration of 0.1 to 5.0 mm into the photosensitive layer immediately above the central axis (a needle tip φ uses a 0.05 mm sapphire needle). The needle is moved parallel to the photosensitive member central axis at a moving speed of 1.4 mm / second. The resistance value applied to the needle at this time is continuously measured with a scratch tester.

In Equation 1, X ₁ , X ₂ , X ₃ ... X ₂₄ are values obtained by measuring the resistance generated when the needle cuts the surface layer of the photoreceptor along the central axis with respect to the time axis. This variation in resistance value is considered to be caused by the cutting resistance of the surface layer that the needle receives. The frequency of resistance value measurement by this cutting resistance is a frequency band of 10 Hz to 10 kHz. FIG. 5 is a measurement graph of the resistance generated by the cutting resistance.

Each X value in FIG. 5 is a measured value of resistance applied to the needle every 5 seconds between the start of measurement and 60 seconds. For example, X ₁ and X ₂ are the maximum resistances of 0 to 5 seconds after the start of measurement. Value and minimum value are shown. _{That, X 1, X 3, X} 5, ··· X 23 is the maximum value of the resistance generated each 5 seconds the time _{axis, X 2, X 4, X} 6, ··· X 24 each time axis This is the minimum value of resistance generated in 5 seconds. (However, the unit of _Xn is mN)
Hereinafter, the meanings of the formulas 2 and 3 will be described.

  In Equation 2, S is represented by the following equation.

S = 10 log {(ME) / 24E}
S represents a conceptual value obtained by dividing the average value of resistance applied to the needle by the fluctuation value (variation) of the resistance. The larger the value of S, the smaller the resistance that the resistance received by the needle changes with the movement of the surface layer, and the constant value. It shows that you are doing. That is, when S is 1.0 or more, it is considered that the surface layer of the photoreceptor exhibits a more uniform resistance value regardless of the location against the cutting stress of a small object such as the tip of a needle. This is considered to mean that the surface layer of the photosensitive member is less likely to be adhered with foreign matters and has few local inhomogeneous places. Actually, from the examples described later, white spots are likely to occur when S is less than 1.0, and when S is greater than 10.0, the surface layer tends to be soft, and the surface layer is worn by the cleaning blade. , Easy to be shaved. Furthermore, 3.0 or more and 10.0 or less are preferable.

  In Equation 3, K is represented by the following equation.

K = 10 log {(ME) / 24}
K is a conceptual value indicating an average value of resistance applied to the needle. When 20.0 <K <55.0, an appropriate frictional force is generated between the photoreceptor and the needle, and the photoreceptor is Even a member that rubs the surface of the photosensitive member such as a cleaning blade exhibits a characteristic that it is not easily worn. That is, when the K is 55.0 or more, the surface of the photoconductor is very difficult to scrape, and even if the surface layer is homogeneous, white spots are likely to occur during long-term use. Easy to cut.

  The meanings of the formulas (2) and (3) mean that the surface has a very uniform surface, which means that the surface has a very uniform resistance that does not vary even when measuring a small amount of a sapphire needle. ing.

  When forming a surface layer of a photoreceptor having the above surface film properties, selection of fine particles having a lubricity in the surface layer, binder and solvent, and dispersion conditions for sufficient dispersion are important. It becomes an element. As a result, it is possible to stably control the dispersion state, and to obtain a photoconductor having stable performance with high image quality, high reliability, low cost, and high durability that can perform stable image formation and cleaning for a long time without variation. I can do it.

  In order to form a surface exhibiting the characteristics of the present invention, it is necessary to disperse the particles very uniformly. When the particles extend, it is preferable to use a material that extends uniformly.

  In the present invention, fine particles having a remarkably small surface energy and a large effect as a lubricant are used for the surface layer. The fine particles having lubricity according to the present invention are preferably resin fine particles containing fluorine atoms, or periodicity. Examples thereof include metal oxide particles selected from metals in the third or fourth period of the table. Among the metal oxide particles, preferably, metal oxides such as magnesium oxide, silica, titanium oxide, zinc oxide, alumina, iron oxide and the like, and composite metal oxide particles thereof are mentioned, among which fine particles containing silicon atoms That is, silica particles are preferably used.

  The resin containing a fluorine atom according to the present invention is a resin containing a fluorine atom, for example, a homopolymer or copolymer of a fluorine-containing polymerizable monomer, or a fluorine-containing polymerizable monomer and a fluorine-free polymerizable monomer. It is a copolymer. The fluorine-containing polymerizable monomer has the general formula

(In the formula, at least one group of R _{4 to} R ₇ is a fluorine atom, and the remaining groups are each independently a hydrogen atom, a chlorine atom, a methyl group, a monofluoromethyl group, a difluoromethyl group, or trifluoro). Is a methyl group). Preferable fluorine-containing polymerizable monomers include ethylene tetrafluoride, ethylene trifluoride, ethylene trifluoride chloride, propylene hexafluoride, vinyl fluoride, vinylidene fluoride, ethylene difluoride dichloride and the like. Two or more types of monomers may be used as the fluorine-containing polymerizable monomer.

  Examples of the fluorine-free polymerizable monomer include vinyl chloride. Two or more types of monomers may be used as the fluorine-free polymerizable monomer.

  All of the fluororesin fine particles are preferably made of a homopolymer or copolymer of a fluoropolymerizable monomer among the above-mentioned constituent materials, more preferably polytetrafluoroethylene (PTFE) or polytrifluoride. Ethylene, ethylene tetrafluoride-hexafluoropropylene copolymer, polyvinylidene fluoride, especially polytetrafluoroethylene.

  As an effect of lubrication of the fluorine-containing resin fine particles, we have found that a good lubricity can be obtained when the lubricating component forms a thin layer on the surface due to the spreading of the particles. It is expected that this can be achieved with moderate softness and elongation. At this time, in order to spread uniformly, the fluororesin fine particles are preferably particles having a crystallinity lower than usual. For example, in the case of polytetrafluoroethylene particles, polytetrafluoroethylene particles having a low crystallinity Is preferred. Preferred crystallinity is less than 90%. When the degree of crystallinity is low, the spreadability is good, so that a thin release layer is uniformly formed on the surface, and good transferability can be provided on the front surface of the photoreceptor. By dispersing such particles in the coating very uniformly, the resulting surface layer has a uniform resistance when scratched with a needle and falls within the scope of the present application.

  The crystallinity of the fluororesin fine particles is measured by wide-angle X-ray diffraction measurement. The generated diffraction peak is separated into crystalline and amorphous, and after correcting the baseline, the crystalline and amorphous total X It is expressed as a percentage (%) of the X-ray integral intensity (numerator) of the crystalline to the line integral intensity (denominator).

  In the present invention, the wide-angle X-ray diffraction measurement device and the measurement conditions were measured as follows, but other measurement devices and the like may be used as long as the same result is obtained.

X-ray generator: Rigaku RU-200B
Output: 50kV, 150mA
Monochromator: Graphite Radiation source: CuKα (0.154184 nm)
Scanning range: 3 ° ≦ 2θ ≦ 60 °
Scanning method: θ-2θ
Scanning speed: 2 ° / min
In addition, since the fluororesin particles have strong hydrophobicity and low affinity with solvents and binders, it is important to select a dispersion aid, and there is an interaction between the fluororesin particles and the binder. Agents, fluorine surfactants and the like are preferably used.

  The average molecular weight of the polymer constituting the fluorine-containing resin fine particles is not particularly limited as long as the object of the present invention can be achieved, but usually the range of 10,000 to 1,000,000 is preferable.

  As the binder resin in the surface layer, it is preferable to use a resin having a surface active group that assists the dispersibility of the fluororesin fine particles in the partial structure of the resin. For example, a polycarbonate or polyarylate having a siloxane group in the partial structure A fluorinated graft acrylic resin or the like is preferable. The molecular weight of these resins is preferably 10,000 to 100,000.

  As the resin fine particles containing fluorine atoms, fine particles having a volume average primary particle size in the range of 0.05 to 0.3 μm are used. In particular, 0.1 to 0.2 μm is preferable.

  The number average primary particle diameter is a measured value as the average diameter in the ferret direction by image analysis by magnifying fine particles 10,000 times by transmission electron microscope observation, randomly observing 100 particles as primary particles.

  Further, when the surface layer is formed using the present invention, it is preferable to increase the ratio of the fluorine-containing resin fine particles in the surface layer, and at least 5% by mass to 30% by mass with respect to the binder resin. It is preferable to use in.

  If it is less than 5% by mass, it is difficult to form a surface layer satisfying a contact angle of 90 ° or more. If it is more than 30% by mass, the surface layer becomes a fragile film, and scratches are likely to occur.

  Further, the dispersion of the fluororesin fine particles according to the present invention is a low-boiling solvent having good dispersibility, preferably an organic solvent having a boiling point of 120 ° C. or lower under atmospheric pressure (for example, THF, ethanol, toluene, dichloroethane, etc. ) Is preferably used. By using such a low-boiling solvent, a stable dispersion can be produced while suppressing the cohesiveness between the fluororesin fine particles. At the same time, the dispersion liquid is adjusted and used as a coating liquid (the dispersion liquid may become the coating liquid as it is), and a quantity-regulating coating device (a coating device that controls the coating amount to control the film thickness of the surface layer) The surface layer is formed and dried to make the film thickness of the surface layer constant, prevent aggregation of the fluororesin fine particles, and form a surface layer having a uniform low surface energy.

  In the present invention, as the metal oxide particles such as silica which are preferably used along with the fluorine-containing resin fine particles, fine particles having a number average primary particle diameter in the range of 0.05 to 0.3 μm are used. In particular, 0.01 μm to 0.1 μm is preferable. The number average primary particle diameter is a measured value as the average diameter in the ferret direction by image analysis by magnifying fine particles 10,000 times by transmission electron microscope observation, randomly observing 100 particles as primary particles.

  Metal oxide particles having a number average primary particle size of less than 3.0 nm are difficult to uniformly disperse in the surface layer, tend to form aggregated particles, and Ra and Rz are likely to be larger than the above range. The contact friction of the agent increases and the generation of reversely chargeable toner increases, and the counter development system tends to cause fogging, increase toner scattering, and decrease the density at the tip. On the other hand, metal oxide particles having a number average primary particle size larger than 150 nm tend to make large irregularities on the surface layer, and Ra and Rz tend to be larger than the above ranges. It is easy to increase toner scattering and to reduce the density of the tip.

  Further, as the metal oxide particles to be contained in the surface layer, it is preferable to use metal oxide particles which have been subjected to surface treatment and have a degree of hydrophobicity as defined below of 50 or more and a degree of hydrophobicity distribution of 25 or less. .

  Since fine particles such as silica have a large number of hydroxyl groups on the surface, blocking these hydroxyl groups to increase the degree of hydrophobicity prevents fogging and a decrease in tip concentration, and is highly durable and sharp. It is preferable for forming an electrophotographic image having good properties.

  In order to increase the degree of hydrophobicity of the metal oxide particles, the surface of silica or the like can be produced by surface treatment using a trimethylsilylating agent. Examples of the trimethylsilylating agent include hexamethyldisilazane, N-methyl-hexamethyldisilazane, N-ethyl-hexamethyldisilazane, hexamethyl-N-propyldisilazane and the like. It is particularly preferred to use disilazane.

  Moreover, trimethylchlorosilane, trimethylsilanol, methoxytrimethylsilane, ethoxytrimethylsilane, propoxytrimethylsilane, dimethylaminotrimethylsilane, diethylaminotrimethylsilane and the like can be mentioned, and it is particularly preferable to use trimethylsilanol because of good reactivity.

  As a surface treatment method, it is preferable to react silica and a trimethylsilylating agent in the presence of water vapor. In this reaction, the surface treatment is preferably performed at a partial pressure of the water vapor of 4 to 20 kPa, preferably 5 to 15 kPa.

  The reaction between the silica and the trimethylsilylating agent is carried out when the silica having a higher degree of hydrophobicity is obtained in a short reaction time, and the partial pressure of the gas phase of the trimethylsilylating agent is 50 to 200 kPa, preferably 80 to 150 kPa. It is preferable to carry out under such a condition.

  Furthermore, the above reaction may be carried out in an atmosphere consisting only of a trimethylsilylating agent and water vapor. However, it is common to dilute these with an inert gas such as nitrogen or helium for use in the reaction. It is. In that case, the total pressure in the reaction atmosphere is generally 150 to 500 kPa, preferably 150 to 250 kPa.

  In order to further increase the reactivity, a basic gas such as ammonia, methylamine or dimethylamine, preferably ammonia may be present in the reaction atmosphere as necessary.

  The reaction temperature between silica and the trimethylsilylating agent is preferably 130 to 300 ° C, and preferably 150 to 250 ° C, taking into account the good reactivity of the hydrophobization reaction and the risk of decomposition of the trimethylsilylating agent. In general, the higher the reaction temperature in the above range, the higher the hydrophobicity of the resulting silica.

In addition, the metal oxide particles that are surface-treated with a polymer containing methylhydrogensiloxane units (— (HSi (CH ₃ ) O) —) are also preferred.

  The surface layer contains a binder resin that helps dispersibility of the metal oxide particles. As the binder resin, polycarbonate and polyarylate are preferable. The molecular weight of these polycarbonates and polyarylates is preferably 10,000 to 100,000.

  The ratio of the metal oxide particles in the surface layer is preferably used in an amount of at least 5% by mass and not more than 30% by mass with respect to the binder resin. Within this range, there is little wear and the roughness of the halftone image due to the occurrence of scratches is small. In addition, cracks and the like are unlikely to occur.

  In the present invention, the surface layer containing fine particles having lubricity is obtained by dispersing the fine particles having lubricity mixed in a solution with a medium such as a ball mill, ultrasonic dispersion, dispersion by high-pressure liquid collision, or under high pressure. It is possible to manufacture by applying a coating solution manufactured using a dispersion obtained by circulating the liquid dispersion step and the filtration step by a plurality of times.

  In particular, in the present invention, the surface layer containing the fine particles having lubricity is obtained by circulating the step of dispersing the fine particles having lubricity mixed in the solution by liquid collision under high pressure and the filtration step a plurality of times. It is preferable to manufacture by applying a coating solution manufactured using the obtained dispersion.

  The above-described step of dispersing by high-pressure liquid collision according to the present invention (hereinafter simply referred to as high-pressure liquid collision dispersion step) generates a high-speed flow by any method and causes liquids to collide with each other. In addition, it is a collective term for devices equipped with the function of promoting emulsification and dispersion by effectively utilizing the turbulent flow, shearing, and cavitation effects caused by high-speed flow and atomizing the material to be treated (dispersoid) in the liquid. As such a liquid collision dispersion device under high pressure, there is a high-pressure homogenizer. Specifically, a liquid to be treated is pumped into a narrow flow path such as an orifice by a plunger pump or a rotary pump and injected. The liquids to be processed are collided from the front. The turbulent flow and the shearing action that occur when the liquids to be treated collide with each other cause crushing from the inside of the dispersoid, and the dispersoid in the liquid to be treated is remarkably atomized.

  As such a liquid collision dispersion device under high pressure, a type using a high-speed injection by a valve plate marketed as a “high pressure homogenizer” (APV Gorin, Runny, Soabi, Nippon Seiki, etc.) ), A type that causes high-speed collision in a slit-shaped flow path (“Microfluidizer” manufactured by Microfluidics), and a type that causes high-speed collision in a single-character flow path that is connected in phase by 90 ° ( "Nanomizer" manufactured by Yoshida Kikai Kogyo Co., Ltd.), a type that generates multiple collisions between liquids and fluids within the same nozzle ("Nanomaker" manufactured by SGS Engineering Co., Ltd.), and fluids in a flat channel element Collision type ("Aqua" manufactured by Aquatech) or jetting from an opposing orifice into an aspheric structure room And the like type (produced by "ULTIMIZER" Sugino Machine Co., Ltd.).

  These high-pressure liquid collision dispersers have some differences in the dispersion effect depending on the type of fluororesin fine particles due to the characteristics of the device type. Compared to the case where it is used, atomization progresses at a remarkably high efficiency, and a dispersion having a uniform particle size distribution can be obtained.

  The dispersion that has passed through the liquid collision dispersion process under high pressure according to the present invention then enters the filtration process, and causes the clogging of the liquid collision dispersion equipment under high pressure by circulating the dispersion process and the filtration process. Aggregated particles of the fluorine-containing resin fine particles can be removed, and a dispersion liquid having a uniform particle size distribution can be obtained.

  In the filtration process, a filter is installed to remove the overdispersed agglomerates generated in the liquid collision dispersion equipment under high pressure, and the dispersion liquid that has passed through the filtration process is circulated again to the disperser, and the orifice of the liquid collision dispersion equipment under high pressure. The dispersion liquid is circulated and dispersed a plurality of times while preventing the mixing of the particles blocking the flow path.

  A preferable discharge pressure at the time of the liquid collision is 50 MPa to 150 MPa. And the filter used by the filtration process connected after that has a preferable mesh filter of 20-100 micrometers.

  As described above, a fluorine-containing resin fine particle dispersion having a uniform average primary particle size of 0.3 μm or less is obtained by circulating a liquid collision dispersion step and a filtration step under high pressure a plurality of times to produce a fluorine-containing resin fine particle dispersion. Dispersion can be obtained and clogging can be prevented at the time of dispersion. As a result, a uniform surface layer can be formed using a coating solution prepared from the dispersion, and long-term stable image formation and cleaning can be achieved. It is possible to obtain an inexpensive and highly durable electrophotographic photosensitive member that can be performed with high image quality and high reliability.

  In the conventional dispersion method, a uniform surface layer as in the present application cannot be formed, and the surface uniformity of the present application can be achieved by applying the dispersion strength uniformly to each particle. These effects are particularly important when a spread fluororesin or highly atomized silica particles are dispersed on the surface. The dispersion strength of the present application varies depending on the particles to be dispersed, but in order to obtain a highly uniform surface layer as in the present application, the dispersion stress applied to each particle needs to be uniform. Such dispersion is difficult to obtain with media dispersion, and cannot be achieved unless the dispersion medium is 0.1 mm or less. Other dispersion methods include dispersion by high-pressure liquid collision.

  Here, as the above-mentioned multiple times circulation, the liquid collision dispersion step and the filtration step may be carried out a plurality of times (preferred number of circulation: circulation of 5 to 100 times). The process may be completed, and the batch of the liquid collision dispersion process and the filtration process for each time may be repeated. The number of circulations in the latter batch method is preferably 2-30.

  FIG. 6 illustrates an example of a dispersion treatment apparatus that circulates the liquid collision dispersion step and the filtration step under high pressure.

  In FIG. 6, the material to be dispersed charged from the non-dispersed material charging container 1 is sent to the dispersion step A. That is, the pipe is filled during the suction-discharge process of the high-pressure pump 2. As the high-pressure pump, a hydraulic pump or a plunger pump is used. The object to be dispersed is pumped to the liquid collision jig 4 in the pump compression process, and is moved in a jig having one to several orifices 7 (diameter 50 μm to 2 mm, length 2 to 10 mm). Liquid collision occurs. Thereafter, the material to be dispersed is sent to the filtration step B, filtered by the filtration filter 9, then subjected to a plurality of circulation dispersions, and then sent to the sample receiving container 5. In the figure, 3 is a high-pressure pipe, 6 is a pressure gauge, and 8 is a three-way valve.

  The electrophotographic photoreceptor of the present invention preferably comprises a layer containing at least a charge generating substance and a charge transporting substance, and a surface layer (protective layer) laminated thereon. The surface layer is preferably formed of a charge transport layer.

  As a coating processing method for producing the electrophotographic photosensitive member according to the present invention, a coating processing method such as dip coating, spray coating, circular amount regulation type coating or the like is used. In order to prevent the film from being dissolved as much as possible, and to achieve uniform coating processing, it is preferable to use a coating processing method such as spray coating or circular amount regulation type (circular slide hopper type is a typical example). It is most preferable that the protective layer of the present invention uses the circular amount regulation type coating method. The circular amount regulation type coating is described in detail in, for example, Japanese Patent Application Laid-Open No. 58-189061.

  Examples of the coating apparatus include a coating apparatus using a circular slide hopper type coating head or an extrusion type coating head. Among these, for example, a coating device having a circular slide hopper type coating head described in Japanese Patent Application No. 2005-363648 (hereinafter also referred to as a circular slide hopper type coating device) is preferably used. The coating apparatus having such a circular coating head does not retain the dispersion liquid in the coating apparatus and forms a surface layer in a one-way manner, so that the dispersed particles do not repeatedly receive agglomeration share in the dispersion liquid and are uniform. A surface layer can be formed. Moreover, since a dispersion can be prepared every time the photoreceptor is manufactured, aggregation and sedimentation of the dispersion over time can be prevented, and the lower layer already formed on the cylindrical conductive support can be dissolved at the time of surface layer formation. Since it can be applied, the surface layer having a uniform dispersibility can be formed with little aggregation of the fluororesin fine particles and the like even during coating and drying. In the bead formation coating, the coating film thickness can be accurately controlled by the flow rate of the coating liquid discharged from the coating apparatus, and the optically uniform surface layer can be formed with little variation in the film thickness.

  The electrophotographic photoreceptor of the present invention preferably comprises a layer containing at least a charge generating substance and a charge transporting substance and a surface layer (protective layer) laminated thereon, and the surface layer is a charge transporting layer. It is preferable that it is formed. Hereinafter, the constitution of the electrophotographic photoreceptor of the present invention will be described.

  In the present invention, the electrophotographic photosensitive member means an electrophotographic photosensitive member constituted by giving an organic compound one of a charge generating function and a charge transporting function which are indispensable for the constitution of the electrophotographic photosensitive member. All known organic electrophotographic photoreceptors such as a photoreceptor composed of a known 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 are contained.

  A preferred layer structure of the electrophotographic photoreceptor of the present invention is a layer structure in which an intermediate layer, a charge generation layer, a charge transport layer, and a surface layer (protective layer) are disposed in this order on a conductive support. Hereinafter, the negatively charged photoreceptor having the above-described layer structure will be described.

Conductive Support The conductive support used in the photoreceptor of the present invention may be either a sheet or a cylinder, but in order to design an image forming apparatus in a compact manner, a cylindrical conductive support is used. Is preferred.

  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. A conductive support is preferred. Exceeding the roundness and shake range makes it difficult to form a good image.

As the conductive material, 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 treatment 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, an intermediate layer having a barrier function may be provided between the conductive support and the photosensitive layer.

  In the present invention, in order to improve the adhesion between the conductive support and the photosensitive layer, or to prevent charge injection from the support, an intermediate layer (including an undercoat layer) is provided between the support and the photosensitive layer. Including) can also be provided. Examples of the material for the intermediate layer include polyamide resins, vinyl chloride resins, vinyl acetate resins, and copolymer resins containing two or more of these resin repeating units. Of these subbing resins, a polyamide resin is preferable as a resin capable of reducing the increase in residual potential due to repeated use. The film thickness of the intermediate layer using these resins is preferably 0.01 to 0.5 μm.

  The intermediate layer most preferably used in the present invention includes an intermediate layer using a curable metal resin obtained by thermally curing an organic metal compound such as a silane coupling agent or a titanium coupling agent. As for the film thickness of the intermediate | middle layer using curable metal resin, 0.1-2 micrometers is preferable.

  Further, the intermediate layer preferably used in the present invention includes an intermediate layer in which titanium oxide fine particles (average particle diameter: 0.01 to 1 μm) subjected to hydrophobic surface treatment are dispersed in a binder such as polyamide resin.

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.

  A known charge generation material (CGM) can be used as the charge generation material (CGM). For example, a phthalocyanine pigment, an azo pigment, a perylene pigment, an azulenium pigment, or the like can be used. Among these, the CGM that can minimize the increase in residual potential due to repeated use has a three-dimensional and potential structure that can form a stable aggregate structure among a plurality of molecules. Specifically, a phthalocyanine having a specific crystal structure. CGM of pigments and perylene pigments. For example, CGMs such as titanyl phthalocyanine having a maximum peak at a Bragg angle 2θ of 27.2 ° with respect to Cu—Kα rays and benzimidazole perylene having a maximum peak at 2θ of 12.4 have little deterioration due to repeated use. Potential increase can be reduced.

  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 0.01 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. Among these, the CTM capable of minimizing the increase in residual potential due to repeated use has a high mobility and an ionization potential difference from the combined CGM of 0.5 (eV) or less, preferably 0 .25 (eV) or less.

  The ionization potential of CGM and CTM is measured with a surface analyzer AC-1 (manufactured by Riken Keiki Co., Ltd.).

  Examples of the resin used for the charge transport layer (CTL) include polystyrene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, polyurethane resin, phenol resin, polyester resin, alkyd resin, and polycarbonate. Resin, silicone resin, melamine resin, and copolymer resin containing two or more of repeating units of these resins. In addition to these insulating resins, high molecular organic semiconductors such as poly-N-vinylcarbazole can be used.

  Most preferred as a binder for these CTLs is a polycarbonate resin. The polycarbonate resin is most preferable in improving the dispersibility and electrophotographic characteristics of CTM. 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 have a two-layer structure in order to achieve the surface properties of the present invention. In other words, the lower charge transport layer may have a layer structure that emphasizes electrostatic properties, and the upper charge transport layer may have a layer structure that emphasizes surface properties.

The surface layer containing fine particles having lubricity according to the present invention and having the above surface characteristics preferably contains an antioxidant in the surface layer. By containing the antioxidant and fine particles having lubricity according to the present invention in the surface layer, fluctuations in the characteristics of the surface layer during repeated use can be prevented, and occurrence of fogging and a decrease in tip concentration in the counter development method can be prevented. In addition, a good electrophotographic image can be provided. Antioxidants are substances that have the property of preventing or suppressing oxidation action under conditions of light, heat, discharge, etc., against auto-oxidizing substances present in the photoreceptor or on the photoreceptor surface.
(1) Radical chain inhibitor ・ Phenol antioxidant (hindered phenol)
・ Amine antioxidants (hindered amines, diallyldiamines, diallylamines)
・ Hydroquinone antioxidant (2) Peroxide decomposer ・ Sulfur antioxidant (thioethers)
・ Phosphoric antioxidants (phosphites)
Etc.

  Among the antioxidants, hindered phenol-based and hindered amine-based antioxidants are particularly effective in preventing fogging and image blurring at high temperatures and high humidity.

  The content of the hindered phenol-based or hindered amine-based antioxidant in the surface layer is preferably 0.01 to 20% by mass. For example, there are compounds represented by the following structural formula.

  Specifically, the following compounds, for example, “Irganox 1076”, “Irganox 1010”, “Irganox 1098”, “Irganox 245”, “3,5-di-tert-butyl” as hindered phenols. Examples of the “-4-hydroxybiphenyl” and hindered amine system include “Sanol LS2626”, “Sanol LS765”, “Sanol LS770”, and the like.

  The surface layer preferably contains a charge transport material. As the charge transport material (CTM), a known hole transport property (P-type) charge transport material (CTM) is preferably used. 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 mass ratio of the binder resin and the charge transport material in the surface layer is preferably 30 to 200 parts by mass, and more preferably 50 to 150 parts by mass with respect to 100 parts by mass of the binder. The thickness of the surface layer is preferably 0.5 to 10 μm.

  As a solvent or dispersion medium used for forming each layer such as an intermediate layer, charge generation layer, charge transport layer, protective layer (surface layer), n-butylamine, diethylamine, ethylenediamine, isopropanolamine, triethanolamine, triethylenediamine N, N-dimethylformamide, acetone, methyl ethyl ketone, methyl isopropyl ketone, cyclohexanone, benzene, toluene, xylene, chloroform, dichloromethane, 1,2-dichloroethane, 1,2-dichloropropane, 1,1,2-trichloroethane, 1, , 1,1-trichloroethane, trichloroethylene, tetrachloroethane, tetrahydrofuran, dioxolane, dioxane, methanol, ethanol, butanol, isopropanol, ethyl acetate, butyl acetate, dimethyl Sulfoxide, and methyl cellosolve. Although this invention is not limited to these, Dichloromethane, 1, 2- dichloroethane, methyl ethyl ketone, etc. are used preferably. These solvents may be used alone or as a mixed solvent of two or more.

  Next, as a coating processing method for producing the electrophotographic photosensitive member of the present invention, coating processing methods such as dip coating, spray coating, and circular amount regulation type coating are used. In order to prevent the lower layer film from being dissolved as much as possible, and in order to achieve uniform coating processing, it is preferable to use a coating processing method such as spray coating or circular amount regulation type (a circular slide hopper type is a typical example). It is most preferable that the protective layer of the present invention uses the circular amount regulation type coating method. The circular amount regulation type coating is described in detail in, for example, Japanese Patent Application Laid-Open No. 58-189061.

  Next, the developer according to the present invention will be described.

<Career>
The carrier according to the present invention has a volume average particle size of 10 to 60 μm and a saturation magnetization value of 20 to 80 emu / g. By using a carrier having a small carrier particle size and a low saturation magnetization value, the magnetic brush on the developing sleeve is softened, and the soft development can be performed by the counter development method, and the fog and the tip density are lowered. Can be prevented.

  As the magnetic particles of the carrier used in the present invention, iron powder, magnetite, various ferrites and the like can be used, and magnetite and various ferrites are preferable.

  The carrier according to the present invention preferably has an average particle size of about 10 to 60 μm, more preferably an average particle size of 15 to 55 μm.

  When the average particle size is less than 10, carriers are likely to be scattered and carrier adhesion to the photoreceptor is likely to occur. If it exceeds 60 μm, the ears on the magnetic brush are likely to be rough, making it difficult to adapt to the soft development method.

  The volume average particle diameter is a volume-based average particle diameter measured by a laser diffraction particle size analyzer “HELOS” (manufactured by Sympatec Corporation) equipped with a wet disperser.

The magnetization characteristics of the carrier magnetic particles themselves are preferably 20 to 80 emu / g in saturation magnetization. When the saturation magnetization is less than 20 emu / g, the magnetic binding force to the developing sleeve is small, so that the carrier adheres to the image forming member and the magnetic brush becomes small, so that a high density image cannot be obtained. On the other hand, if it exceeds 80 emu / g, the magnetic brush becomes stiff, and the counter development method tends to cause a decrease in the density at the tip.

  The saturation magnetization is measured by “DC magnetization characteristic automatic recording device 3257-35” (manufactured by Yokogawa Electric Corporation).

<Carrier resin coating>
The carrier according to the present invention preferably comprises magnetic particles as a core (core) and the surface thereof is coated with a resin. The resin used for coating the carrier core material is not particularly limited, and various resins can be used. For the positively chargeable toner, for example, a fluorine-based resin, a fluorine-acrylic resin, a silicone-based resin, a modified silicone-based resin, or the like can be used, and a condensation-type silicone resin is preferable. Conversely, for negatively chargeable toners, for example, acrylic-styrene resins, mixed resins of acrylic-styrene resins and melamine resins, and cured resins thereof, silicone resins, modified silicone resins, epoxy resins. , Polyester resins, urethane resins, polyethylene resins, and the like. Preferred are mixed resins of acrylic-styrene resins and melamine resins, cured resins thereof, and condensation type silicone resins. Moreover, you may add a charge control agent, an adhesive improvement agent, a primer processing agent, a resistance control agent, etc. as needed.

  As the coating resin, a siloxane-based resin is preferably used, and a resin having a crosslinked structure is preferable. Examples of the siloxane-based resin include a silicone resin.

  In addition, the charge amount and the like can be adjusted by adding a silane coupling agent to the silicone resin. In order to adjust the charge amount, 5 to 50 parts by mass, preferably 7 to 45 parts by mass of the silane coupling agent is added to 100 parts by mass of the silicone resin. If the addition amount is excessive, there is a problem that the hardness of the resin is lowered. If the addition amount is too small, the chargeability-imparting ability is lowered and the purpose cannot be achieved.

  Examples of the silane coupling agent include an alkoxysilane having an amino group or an amine at the terminal.

  Further, it is preferable to use a curing agent in order to form a crosslinked structure in the resin. As a hardening | curing agent, the oxime type hardening | curing agent of the structure shown below can be mentioned, for example.

  The addition amount of the curing agent is 0.1 to 10 parts by mass, preferably 0.5 to 8 parts by mass with respect to 100 parts by mass of the resin.

<Carrier manufacturing method>
The carrier can be manufactured by coating a magnetic particle with a silicone resin or the like a plurality of times and performing a heat treatment.

  The coating method is not particularly limited, and a coating method such as a dipping method or a spray drying method is used. Also, the heat treatment method is not particularly limited, and for example, a dryer or the like in which a coated carrier is put in a bucket and heated to dry can be used.

  The multiple times of coating and heat treatment means that the magnetic particles are coated with a silicone resin, and after the heat treatment, the silicone resin is further coated and the heat treatment step is repeated. For example, the heating temperature is 180 ° C. ≦ first heating temperature ≦ nth heating temperature ≦ 300 ° C.

  If the temperature is low, sufficient crosslinking reaction does not proceed, so that film wear occurs and sufficient durability cannot be obtained. If the temperature exceeds 300 ° C., the film is thermally deteriorated, which is not preferable. Moreover, the low cross-linking component can be eliminated by a plurality of treatments, which is preferable.

  The resin coating amount of the first coating is preferably 40 to 95% by mass of the entire resin coating amount. More preferably, it is 45-90 mass%. On the other hand, the resin coating amount in the second and subsequent final coatings is preferably 5% by mass to 60% by mass, and more preferably 10% by mass to 55% by mass with respect to the total resin coating amount. That is, when the resin coating amount is less than 5% by mass, the final coating cannot be made uniform, and the surface resin layer is uneven, which is not preferable.

  The number of times of coating is not problematic in terms of properties even if the number of times of coating is repeated. However, if the number of times of coating is twice, this property can be satisfied. Therefore, the number of times of coating is preferably 2 from the viewpoint of productivity.

  The apparatus for applying mechanical stress to the carrier is not particularly limited, and for example, a stirring mixer such as a Nauter mixer, a tumbler mixer, a V-type mixer and a W-corn type mixer can be used. Since a device having a low impact energy per unit time such as a Nauter mixer requires a long time to obtain a carrier that satisfies the performance, a Turbler mixer, a V-type mixer, and a W cone type having a high impact force per unit time. It is preferable to use a stirring mixer such as a mixer.

  The coating resin film thickness of the silicone resin on the magnetic particles is preferably 0.2 to 2.0 μm, more preferably 0.3 to 1.5 μm.

  The film thickness of the coating resin was measured by cutting the center of the carrier particles, observing the cut surface with a scanning electron microscope, and extracting several points at random, and taking the average value as the coating resin film thickness.

  The amount of the silicone resin coating resin on the magnetic particles is preferably 0.3 to 15% by mass and more preferably 0.4 to 10% by mass with respect to the magnetic particles.

  The amount of the coating resin was measured with a quantitative carbon analyzer “EMAIA-500” (manufactured by Horiba Seisakusho).

<toner>
The toner is preferably obtained by mixing inorganic fine particles with colored particles containing a binder resin, a colorant and other additives. The volume average particle size of the toner is preferably 3 to 20 μm, and more preferably 5 to 12 μm. The method for producing the colored particles is not particularly limited, and those produced by a pulverization method or a polymerization method can be used. However, in the present invention, a polymer toner produced by a polymerization method capable of obtaining a uniform particle size distribution is more preferable. preferable. 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. Since the polymerized toner is produced by uniformly dispersing the raw material monomers in an aqueous system and then producing the toner, a toner having a uniform toner particle size distribution and shape can be obtained.

  The binder resin used for the toner is not particularly limited, and various conventionally known resins are used. Specific examples include styrene resins, acrylic resins, styrene / acrylic resins, and polyester resins. The colorant is not particularly limited, and a conventionally known material is used. Specific examples include carbon black, nigrosine dye, aniline blue, calcoin blue, chrome yellow, ultramarine blue, dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate and rose bengal. Examples of other additives include charge control agents such as salicylic acid derivatives and azo metal complexes, fixing improvers such as low molecular weight polyolefins and carnauba wax.

  The magnetic toner can be obtained by using magnetic fine particles as a colorant. As the magnetic fine particles, particles such as ferrite and magnetite having an average primary particle diameter of 0.1 to 2.0 μm are used. The addition amount of the magnetic fine particles is preferably 20 to 70% by mass in the toner.

  Further, from the viewpoint of imparting fluidity, it is preferable to mix inorganic fine particles with colored particles. As the inorganic fine particles, inorganic oxide particles such as silica, titania and alumina are preferable, and these inorganic fine particles are more preferably hydrophobized with a silane coupling agent or a titanium coupling agent.

  The electrophotographic photoreceptor of the present invention is found to have a remarkable improvement effect against white spots that are likely to occur particularly when an image is formed with a developer using a polymerized toner.

<Developer>
The developer can be prepared by mixing toner and carrier. The mixing amount of the toner with respect to the carrier is preferably 2 to 10% by mass.

  The mixing apparatus is not particularly limited, and a Nauter mixer, a W cone, a V-type mixer, or the like can be used.

  A developing device of the counter direction developing system will be described with reference to FIG. In the developing device 102, a developing sleeve 120 in which a cylindrical magnet 121 is disposed in a non-rotating manner is disposed in an opening portion of a developing container 110 containing a two-component developer so as to face the photoconductor 101. Rotates in the counter direction with respect to the photosensitive member 101 rotating in the direction of the arrow, and conveys the developer adsorbed and held on the surface of the photosensitive member 101 to the developing unit facing the photosensitive member 101. The magnet 121 has a developing magnetic pole N1 on the photosensitive member 101 side, and the first conveying magnetic pole S3, the second conveying magnetic pole N2, the third conveying magnetic pole S2, and the third conveying magnetic pole N1 are arranged in the rotational direction of the developing sleeve 120 from the developing magnetic pole N1. It has a pumping magnetic pole S1 that constitutes a conveying magnetic pole and a separating magnetic pole.

  The developer in the developing container 110 is attracted and held on the developing sleeve 120 by the action of the pumping pole S1 at the position (pumping position) Q1 on the surface of the developing sleeve 120 corresponding to the pumping magnetic pole S1 of the magnet 121, and the developing blade After the layer thickness is regulated by 122, the developing unit is reached, and a magnetic brush is formed by the action of the developing magnetic pole N 1 in the developing unit to develop the latent image on the photoreceptor 101.

  The developer whose toner density is reduced by the development is held on the developing sleeve 120 and returned to the inside of the developing container 110 by the action of the first and second transport magnetic poles S3 and N2, and the third transport magnetic pole S2 and the pumping magnetic pole S1. At the position (developer dropping position) P1 on the surface of the developing sleeve 120 where the magnetic flux density is the smallest. As described above, the developer sleeve 120 from which the developer has been peeled is adsorbed and held at the pumping position Q1.

  A first agitating and conveying member 123 is installed below the developing sleeve 120 in the developing container 110, and a second agitating and conveying member 124 is further installed via a partition wall 140. These first and second agitating / conveying members 123 and 124 are of a screw type and have a helical screw blade 128 and a plate-like protrusion 130 between the blades.

  The developer having a low toner concentration peeled off from the developing sleeve 120 falls on the first stirring / conveying member 123 and is agitated / conveyed in the axial direction with the adjacent developer by the first stirring / conveying member 123. This is passed to the second agitating and conveying member 124 through an opening (not shown). The second agitating / conveying member 124 conveys the developer and the toner replenished from the replenishing port 118 of the developing container 110 in a reverse rotation to the above while agitating, and an opening (not shown) at the other end of the partition wall 140. And return to the first stirring and conveying member 123 side.

  Next, the process cartridge and the electrophotographic apparatus according to the present invention will be described. FIG. 2 shows a schematic configuration of an electrophotographic apparatus having a process cartridge including an electrophotographic photosensitive member.

  In FIG. 2, reference numeral 1 denotes a drum-shaped photoconductor, which is driven to rotate at a predetermined peripheral speed in the direction of an arrow about an axis C. In the rotating process, the photosensitive member 1 is uniformly charged with a predetermined positive or negative potential on its peripheral surface by the charging unit 2 and then output from an exposure unit (not shown) such as slit exposure or laser beam scanning exposure. Exposure light 3 (exposure means) subjected to enhancement modulation corresponding to a time-series electrical digital image signal of target image information is received. In this way, electrostatic latent images corresponding to target image information are sequentially formed on the peripheral surface of the photoreceptor 1.

  The formed electrostatic latent image is then developed with toner by the developing unit 4 and is taken out from a sheet feeding unit (not shown) between the photosensitive member 1 and the transfer unit 5 in synchronization with the rotation of the photosensitive member 1 and fed. The toner images formed and supported on the surface of the photosensitive member 1 are sequentially transferred onto the transferred material P by the transfer unit 5.

  The transfer material P that has received the transfer of the toner image is separated from the surface of the photosensitive member, introduced into the image fixing means 24, and subjected to image fixing, thereby being printed out as an image formed product (print, copy).

  After the image transfer, the surface of the photoreceptor 1 is cleaned by removing the transfer residual toner by the cleaning unit 6 and further subjected to the charge removal process by the pre-exposure light Pex from the pre-exposure unit (not shown), and then repeatedly. Used for image formation. When the charging unit 2 is a contact charging unit using a charging roller or the like, pre-exposure is not always necessary.

  In the present invention, among the above-described components such as the photoreceptor 1, the charging unit 2, the developing unit 4, and the cleaning unit 6, a plurality of components are housed in a container PC and integrally combined as a process cartridge. The process cartridge may be configured to be detachable from a main body of an electrophotographic apparatus such as a copying machine or a laser beam printer. For example, at least one of a charging unit (charging unit) 2, a developing unit (developing unit) 4, a cleaning unit (cleaning unit) 6, an exposure unit, and a charge removing process is integrally supported together with the photosensitive member 1. Thus, the cartridge can be made into a process cartridge that can be attached to and detached from the apparatus main body using guide means AN such as a rail of the apparatus main body.

  An embodiment of an electrophotographic printer (hereinafter simply referred to as a printer) will be described as a full-color image forming apparatus to which the present invention is applied.

  FIG. 3 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 includes four sets of image forming units (image forming units) 10Y, 10M, 10C, and 10Bk, an endless belt-shaped intermediate transfer body unit 7, and a feeding unit. It comprises a paper 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 has a charging unit 2Y, an exposing 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 four sets of image forming units 10Y, 10M, 10C, and 10K include charging means 2Y, 2M, 2C, and 2K that rotate around the photosensitive drums 1Y, 1M, 1C, and 1K, and image exposure means 3Y, 3M, 3C, 3K, rotating developing means 4Y, 4M, 4C, and 4K, and cleaning means 5Y, 5M, 5C, and 5K for cleaning the photosensitive drums 1Y, 1M, 1C, and 1K.

  The image forming units 10Y, 10M, 10C, and 10K have the same configuration except that the colors of the toner images formed on the photoreceptors 1Y, 1M, 1C, and 1Bk are different, and the image forming unit 10Y is taken as an example in detail. explain.

  The image forming unit 10Y has a charging unit 2Y (hereinafter simply referred to as a charging unit 2Y or a charger 2Y), an exposure unit 3Y, a developing unit 4Y, and a cleaning unit 5Y (around a photosensitive drum 1Y as an image forming body). Hereinafter, the cleaning means 5Y or the cleaning blade 5Y) is simply disposed, and a yellow (Y) toner image is formed on the photosensitive drum 1Y. In the present embodiment, in the image forming unit 10Y, at least the photosensitive drum 1Y, the charging unit 2Y, the developing unit 4Y, and the cleaning unit 5Y are provided so as to be integrated.

  The charging unit 2Y is a unit that applies a uniform potential to the photosensitive drum 1Y. In the present embodiment, a corona discharge type charger 2Y is used for the photosensitive drum 1Y.

  The image exposure means 3Y performs exposure based on the image signal (yellow) on the photosensitive drum 1Y given a uniform potential by the charger 2Y, and forms an electrostatic latent image corresponding to the yellow image. As the exposure means 3Y, the exposure means 3Y includes an LED in which light emitting elements are arranged in an array in the axial direction of the photosensitive drum 1Y and an imaging element (trade name; Selfoc lens), or A laser optical system or the like is used.

In the image forming method of the present invention, when an electrostatic latent image is formed on a photoreceptor, it is preferable to perform image exposure using an exposure beam having a spot area of 2000 μm ² or less. Even when such small-diameter beam exposure is performed, the electrophotographic photosensitive member of the present invention can faithfully form an image corresponding to the spot area. A more preferable spot area is 100 to 1000 μm ² . As a result, an electrophotographic image having a gradation of not less than 800 dpi (dpi is the number of dots per 2.54 cm) can be achieved.

The spot area of the exposure beam is a light intensity distribution plane appearing on the cut surface when the exposure beam is cut along a plane perpendicular to the beam, and in a region where the light intensity is 1 / e ² or more of the maximum peak intensity. It means the corresponding area.

Examples of the light beam used include a scanning optical system using a semiconductor laser and a solid state scanner such as an LED or a liquid crystal shutter. The light intensity distribution includes a Gaussian distribution and a Lorentz distribution, but 1 / e of each peak intensity. ^The area up to ² is the spot area.

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

  Each color image formed by the image forming units 10Y, 10M, 10C, and 10Bk is sequentially transferred onto a rotating endless 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 transfer material P as a transfer material (a support for carrying a fixed final image: for example, plain paper, a transparent sheet, etc.) housed in the paper feed cassette 20 is fed by a paper feed means 21 and a plurality of intermediates. After passing through rollers 22A, 22B, 22C, 22D and registration roller 23, they are conveyed to a secondary transfer roller 5b as a secondary transfer means, and are secondarily transferred onto a transfer material P to transfer a color image all at once. The transfer material P onto which the color image has been transferred is subjected to fixing processing by the fixing unit 24, is sandwiched between paper discharge rollers 25, and is placed on a paper discharge tray 26 outside the apparatus. Here, the transfer medium refers to a transfer support for a toner image on a photosensitive member such as an intermediate transfer member or a transfer material.

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

  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 5b is brought into pressure contact with the endless belt-shaped intermediate transfer body 70 only when the transfer material P passes through the secondary transfer roller 5b.

  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 an endless belt-shaped intermediate transfer body unit 7.

  The image forming units 10Y, 10M, 10C, and 10Bk are arranged in tandem in the vertical direction. An endless 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 endless belt-shaped intermediate transfer body unit 7 includes an endless belt-shaped intermediate transfer body 70 that can be rotated by winding rollers 71, 72, 73, 74, primary transfer rollers 5Y, 5M, 5C, 5Bk, and cleaning means 6b. Consists of.

  Next, FIG. 4 shows a color image forming apparatus using the electrophotographic photosensitive member of the present invention (a copying machine having at least a charging means, an exposing means, a plurality of developing means, a transferring means, a cleaning means, and an intermediate transfer member around the photosensitive member. 1 is a cross-sectional view of a configuration of a laser beam printer). The belt-shaped intermediate transfer body 70 uses an elastic body having a medium resistance.

  Reference numeral 1 denotes a rotary drum type photoconductor that is repeatedly used as an image forming body, and is rotationally driven in a counterclockwise direction indicated by an arrow at a predetermined peripheral speed.

  During the rotation process, the photosensitive member 1 is uniformly charged to a predetermined polarity and potential by the charging unit 2 and then modulated in accordance with a time-series electric digital pixel signal of image information by an image exposure unit 3 (not shown). An electrostatic latent image corresponding to a yellow (Y) color component image of a target color image is formed by receiving image exposure with scanning exposure light or the like by a laser beam.

  Next, the electrostatic latent image is developed with yellow toner as the first color by yellow (Y) developing means (yellow color developing device) 4Y. At this time, the second to fourth developing means (magenta developer, cyan developer, black developer) 4M, 4C, and 4Bk are not activated and do not act on the photoreceptor 1. The yellow toner image of the first color is not affected by the second to fourth developing devices.

  The intermediate transfer member 70 is stretched by rollers 79a, 79b, 79c, 79d, and 79e, and is driven to rotate in the clockwise direction at the same peripheral speed as the photosensitive member 1.

  The first color yellow toner image formed and supported on the photosensitive member 1 is applied to the intermediate transfer member 70 from the primary transfer roller 5a in the process of passing through the nip portion between the photosensitive member 1 and the intermediate transfer member 70. The intermediate transfer (primary transfer) is sequentially performed on the outer peripheral surface of the intermediate transfer body 70 by the electric field formed by the primary transfer bias.

  The surface of the photoreceptor 1 after the transfer of the first color yellow toner image corresponding to the intermediate transfer body 70 is cleaned by the cleaning device 6a.

  Similarly, the second color magenta toner image, the third color cyan toner image, and the fourth color black (black) toner image are sequentially superimposed and transferred onto the intermediate transfer body 70 to correspond to the target color image. A superimposed color toner image is formed.

  The secondary transfer roller 5b is supported in parallel with the secondary transfer counter roller 79b so as to be separated from the lower surface of the intermediate transfer body 70.

  The primary transfer bias for sequentially superimposing and transferring the first to fourth color toner images from the photosensitive member 1 to the intermediate transfer member 70 has a polarity opposite to that of the toner and is applied from a bias power source. The applied voltage is, for example, in the range of +100 V to +2 kV.

  In the primary transfer process of the first to third color toner images from the photosensitive member 1 to the intermediate transfer member 70, the secondary transfer roller 5b and the intermediate transfer member cleaning means 6b can be separated from the intermediate transfer member 70. is there.

When the superimposed color toner image transferred onto the belt-shaped intermediate transfer member 70 is transferred to the transfer material P, which is the second image carrier, the secondary transfer roller 5b is brought into contact with the belt of the intermediate transfer member 70. At the same time, the transfer material P is fed from the pair of paper registration rollers 23 through the transfer paper guide to the belt of the intermediate transfer body 70 to the contact nip with the secondary transfer roller 5b at a predetermined timing. A secondary transfer bias is applied to the secondary transfer roller 5b from a bias power source. By this secondary transfer bias, the superimposed color toner image is transferred (secondary transfer) from the intermediate transfer body 70 to the transfer material P as the second image carrier. The transfer material P that has received the transfer of the toner image is the fixing means 2.
4 and heated and fixed.

  The electrophotographic photosensitive member of the present invention is generally applicable to electrophotographic apparatuses such as electrophotographic copying machines, laser printers, LED printers, and liquid crystal shutter printers, and further displays, recordings, light printing, plate making and the like using electrophotographic technology. It can be widely applied to apparatuses such as facsimiles.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, the aspect of this invention is not limited to this. In the following text, “part” means “part by mass”.

Production of Photoreceptor 1 Photoreceptor 1 was produced as follows.

The surface of the cylindrical aluminum support was cut to prepare a cylindrical conductive support having a ten-point surface roughness Rz = 1.5 (μm).
<Intermediate layer>
The following intermediate layer dispersion was diluted twice with the same mixed solvent, allowed to stand overnight, and then filtered (filter; 5 μm filter) to prepare an intermediate layer coating solution.

Polyamide resin CM8000 (manufactured by Toray Industries, Inc.) 1 part Inorganic particles: Titanium oxide (Number average primary particle size 35 nm: Titanium oxide treated with silica / alumina and methylhydrogenpolysiloxane) 3 parts Methanol 10 parts are mixed as a disperser Using a sand mill, batch dispersion was performed for 10 hours to prepare an intermediate layer dispersion.

  The said coating liquid was apply | coated by the dip coating method, and the intermediate | middle layer with a dry film thickness of 1.0 micrometer was formed on the said support body.

<Charge generation layer: CGL>
Charge generation material (CGM): oxytitanyl phthalocyanine (a titanyl phthalosine pigment having a maximum diffraction peak at a Bragg angle (2θ ± 0.2 °) of 27.3 ° in an X-ray diffraction spectrum by Cu-Kα characteristic X-ray) 24 parts polyvinyl butyral resin “S-LEC BL-1” (manufactured by Sekisui Chemical Co., Ltd.) 12 parts 2-butanone / cyclohexanone = 4/1 (v / v) 300 parts The above composition is mixed, dispersed using a sand mill, and charged. A generation layer coating solution was prepared. This coating solution was applied by a dip coating method to form a charge generation layer having a dry film thickness of 0.5 μm on the intermediate layer.

<Charge transport layer 1 (CTL1)>
Charge transport material (4,4′-dimethyl-4 ″-(α-phenylstyryl)
Triphenylamine) 225 parts Polycarbonate (Z300: Mitsubishi Gas Chemical Co., Ltd.) 300 parts Antioxidant (Irganox 1010: Nihon Ciba Geigy Co., Ltd.) 6 parts Dichloromethane 2000 parts Silicon oil (KF-54: Shin-Etsu Chemical Co., Ltd.) 1 part mixed And dissolved to prepare a charge transport layer coating solution 1. This coating solution was applied onto the charge generation layer by a dip coating method and dried at 110 ° C. for 70 minutes to form a charge transport layer 1 having a dry film thickness of 18.0 μm.

<Preparation of fluororesin fine particle dispersion 1>
The following PTFE particle dispersion was prepared using PTFE particles (average primary particle size 0.12 μm).

PTFE particles (PT1: average primary particle size 0.12 μm, crystallinity 91.3) 200 parts Toluene / tetrahydrofuran (2/8) 600 parts Fluorine-based comb-type graft polymer (trade name GF300, manufactured by Toagosei Co., Ltd.) )
15 parts The above components are mixed, premixed by ultrasonic dispersion, filtered through a 120 μm nylon mesh filter, and then basically a liquid collision dispersion process and a filtration process (20 μm nylon mesh under high pressure) as shown in FIG. The dispersion is continuously circulated (dispersed by “Nanmizer” manufactured by Yoshida Kikai Kogyo Co., Ltd.) and dispersed in a dispersion apparatus having a filter). Was prepared. The discharge pressure at the time of dispersion liquid collision was performed under the condition of a constant pressure of 50 MPa and the average number of circulation of the dispersion liquid of 30 times, but the fluctuation of the discharge pressure was also stable in the range of 50M ± 10 MPa, and there was no clogging in the middle. I was able to distribute. The average particle diameter of the fluororesin fine particles after dispersion was 0.12 μm.

<Charge transport layer 2 (CTL2)>
Fluororesin fine particle dispersion 1 100 parts Charge transport material (4,4′-dimethyl-4 ″-(α-phenylstyryl)
Triphenylamine) 100 parts Polycarbonate (Z300: manufactured by Mitsubishi Gas Chemical Company) 150 parts Antioxidant (Irganox 1010: manufactured by Ciba Geigy Japan) 12 parts THF: Tetrahydrofuran 2800 parts Silicon oil (KF-54: manufactured by Shin-Etsu Chemical Co., Ltd.) 4 parts Were mixed in a four-blade wing mixer and dissolved to prepare a charge transport layer coating solution 2. The proportion of fine particles having lubricity in the solid content of this liquid (all solid content other than the solvent, including silicon oil) is 9.0%. This coating solution is applied onto the charge transport layer 1 by a coating apparatus having a circular slide hopper type coating head described in FIGS. 1 to 6 of Japanese Patent Application No. 2005-363649, and dried at 110 ° C. for 70 minutes. Then, a charge transport layer 2 having a dry film thickness of 2.0 μm was formed, and a photoreceptor 1 was produced.

Preparation of photoconductors 2 to 7 The fluororesin fine particle dispersions 2 to 7 were prepared by changing the dispersion conditions and the like of the fluororesin fine particle dispersion 1 as follows.

<Preparation of fluororesin fine particle dispersion 2>
A fluororesin fine particle dispersion 2 was prepared in the same manner as the fluororesin fine particle dispersion 1, except that the PTFE particles of the fluororesin fine particle dispersion 1 were changed to the following PTFE particles.

PTFE particles (PT1: number average primary particle size 0.12 μm, crystallinity 82.8)
The average particle size at this time was 0.15 μm.

<Preparation of fluororesin fine particle dispersion 3>
A fluororesin fine particle dispersion 3 is prepared with the same formulation as the fluororesin fine particle dispersion 1 except that the discharge pressure at the time of dispersion collision is a constant pressure of 40 MPa and the average number of circulation of the dispersion is 20 times. did.

  The average particle size at this time was 0.18 μm.

<Preparation of fluororesin fine particle dispersion 4>
The fluororesin fine particle dispersion 4 was prepared in the same manner as the fluororesin fine particle dispersion 1, except that the dispersion conditions of the fluororesin fine particle dispersion 1 were changed as follows.

  The dispersion was charged into a circulating ultrasonic disperser with a circulating frequency of 20 kHz and an output of 500 W, and a flow rate of 200 ml / min. Was dispersed for 5 hours. In the middle, filtration was performed with a 20 μm mesh filter.

  The average particle size at this time was 0.15 μm.

<Preparation of fluororesin fine particle dispersions 5 and 6>
Dispersion of fluorine-containing resin fine particle dispersions 5 and 6 under the same dispersion conditions as fluorine-containing resin fine particle dispersion 1 except that the amount of PTFE particles added to fluorine-containing resin fine particle dispersion 1 was changed from 200 parts to 100 parts and 400 parts A liquid was prepared.

<Preparation of fluororesin fine particle dispersion 7>
The same components as in the fluororesin fine particle dispersion 1 are mixed, preliminarily mixed by ultrasonic dispersion, filtered through a 120 μm nylon mesh filter, and then the mixed components have a number average primary particle size of 0.1 mm of zirconium oxide. A media mill disperser (commercially available Ultra Apex Mill (manufactured by Kotobuki Industries Co., Ltd.): a disperser employing a rotandem pin type stirring and centrifugal separation of beads (dispersion media)) The fluororesin fine particle dispersion 7 was prepared by dispersing the fluororesin fine particles and separating the dispersion media. The fluororesin fine particle dispersion 7 also had good bead separation, and the average particle size of the fluororesin fine particles after dispersion was 0.13 μm.

  In the production of the photoconductor 1, the fluororesin fine particle dispersions 2 to 7 prepared by changing the dispersion conditions and the addition amount of the fluororesin fine particles were used in the same manner as the photoconductor 1 except that the addition amounts shown in Table 1 were used. Thus, charge transport layer 2 (CTL2) was produced, and photoreceptors 2 to 7 were produced. Both the dispersion of the fluororesin fine particle dispersions 2 to 7 and the fluctuation of the discharge pressure were stable in the range of 50 M ± 10 MPa, and could be dispersed without clogging on the way. Table 1 also shows the average particle diameter of the fluororesin fine particles 2 to 7 after dispersion.

Production of photoconductor 8 <Production of surface-treated silica fine particles>
Silica particles having an average primary particle size of 40 nm and having a surface treatment with silica hexamethyldisilazane (hydrophobicity 72, hydrophobicity distribution value 20) were prepared. In addition, the hydrophobization degree and the hydrophobization degree distribution value of the metal oxide particles are determined according to the surface treatment conditions (partial pressure of water vapor, partial pressure of the surface treatment agent, total pressure, reaction temperature) together with the surface treatment agent of the metal oxide particles. Etc.).

<Preparation of charge transport layer coating solution>
The surface-treated silica particles were used in the amounts shown in Table 1 in place of the fluorine-containing resin fine particles used for the preparation of the charge transport layer 2 (CTL2) of the photoreceptor 1, and similarly “Nanomizer” manufactured by Yoshida Kikai Kogyo Co., Ltd. The dispersion liquid is prepared under the condition that the discharge pressure at the time of collision of the dispersion liquid is a constant pressure of 40 MPa and the average circulation frequency of the dispersion liquid is 20 times, and the dispersion liquid is mixed in the same manner as the photosensitive member 1 and the charge transport layer coating liquid is mixed. 2 ′ is prepared, and this coating solution is applied onto the charge transport layer 1 with a circular slide hopper type coater, dried at 110 ° C. for 70 minutes to form a charge transport layer 2 ′ having a dry film thickness of 2.0 μm. Thus, a photoreceptor 8 was produced.

<Preparation of photoconductors 9 and 10>
<Preparation of fluororesin fine particle dispersion 9>
A fluorine-containing resin fine particle dispersion 9 was prepared by dispersing under the following dispersion conditions with the same liquid composition as the fluorine-containing resin fine particle dispersion 2.

  The above components are first mixed, premixed by ultrasonic dispersion, filtered through a 120 μm nylon mesh filter, and the mixed components are number average primary particle diameters of 0.3 mm glass beads (manufactured by Hibee 24 Ohara). Fluorine-containing resin in which the dispersion media is filled into a media mill disperser (commercially available Dynomill) filled with 80% beads of the solvent liquid level, and the fluorinated resin particles are dispersed for 3 hours to separate the dispersion media. A fine particle dispersion 1 was prepared. The average particle diameter of the fluororesin fine particles after dispersion was 0.29 μm.

<Preparation of fluororesin fine particle dispersion 10>
The fluororesin fine particle dispersion 10 was prepared by the same formulation and dispersion conditions as the fluororesin fine particle dispersion 1 except that the fluorine-based comb-type graft polymer was removed from the fluororesin fine particle dispersion 1. Prepared.

<Charge transport layer 2 (CTL2)>
A charge transport layer coating solution was prepared by using the same amount of the fluororesin fine particle dispersions 9 and 10 in place of the fluororesin fine particle dispersion 1 of the photoreceptor 1. Photoconductors 9 and 10 were prepared by coating on top.

<Preparation of silica-containing fine particle dispersion 11>
Silica fine particles used in the photoreceptor 8 were dispersed under the same conditions as the fluororesin fine particle dispersion 9 to prepare a silica-containing fine particle dispersion 11.

<Production of charge transport layer coating solution 2 ">
A coating solution was prepared in the same manner as the charge transport layer coating solution 2 ′ of the photoconductor 8, and coated and dried under the same conditions as the photoconductor 8 to prepare a photoconductor 11.

  A photoconductor similar to the photoconductor 1 except that the charge transport layer 2 was not provided was prepared as a photoconductor 12.

[Resistance evaluation method]
About each produced photoreceptor, the surface layer was evaluated using the scratch strength tester (made by Shinto Kagaku Co., Ltd.). The evaluation was made by causing a needle having a sharp tip (0.05φ) and a diameter of 0.05 mm to enter the surface of the photoreceptor perpendicularly to the scratch strength tester under the condition of 3 mm penetration as described above. The resistance value applied to the needle of each photoconductor was continuously measured. For the resistance value applied to the needle, the signals were continuously taken into a personal computer and processed, and the above equations 1 to 3 were calculated. The calculated S and K values are shown in Table 1.

[Image evaluation method]
Each photoconductor obtained was set in a commercially available digital copying machine Konica “Sitios” 7085 (manufactured by Konica Minolta Business Technologies, Inc.) having a scorotron charger, a semiconductor laser image exposure device, a reversal developing means, and a cleaning blade. A copy evaluation was conducted. A total of 100,000 character images were printed, and character image quality (middle defect), photoconductor film thickness loss, transfer rate, and cleaning properties were evaluated.

Other conditions for image formation Process speed: 420 mm / sec
Charging conditions: A scorotron band electrode was used as the band electrode, and the grit voltage of the band electrode was set to 650V.

  Developer: The developer used was prepared from the following toner and carrier.

<Example of toner production>
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 dropwise addition, the liquid temperature was raised to 80 ° C. ± 1 ° C. and stirring was performed for 6 hours. Next, the liquid temperature was cooled to 40 ° C. or less, stirring was stopped, and filtration was performed with 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 mass average molecular weight = 17,000, and the 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 100-liter GL reaction kettle equipped with a temperature sensor, a cooling pipe, a nitrogen introducing device, and a comb-shaped baffle 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 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 dropwise addition, the liquid temperature was controlled at 72 ° C. ± 2 ° C., and the mixture was heated and stirred for 6 hours. Furthermore, the liquid temperature was raised to 80 ° C. ± 2 ° C., and the mixture was heated and stirred for 12 hours. The liquid temperature was cooled to 40 ° C. or lower, and stirring was stopped. The filtrate is filtered through a pole filter, and this filtrate is designated as “Latex-B”.

  In addition, 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 mass average molecular weight = 245,000, and the mass 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, cooling pipe, nitrogen introduction device, particle size and shape monitoring device, latex-A = 20.0 kg, latex-B = 5.2 kg, and 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, the temperature rise was started, the temperature was raised to a liquid temperature of 85 ° C. in 60 minutes, and the particles were 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.

  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. 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 liquid using 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.

  The number average particle diameter was 2.3 μm, and the ratio of the shape factor of 1.0 to 1.6 was 62.7%. The method for measuring the number average particle diameter and the shape factor at this time is as follows.

(Number average particle size)
The number particle size distribution and the number variation coefficient of the toner are measured by a Coulter Counter TA- or Coulter Multisizer (manufactured by Coulter Co.). 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.

(Shape factor)
The “shape factor” of the toner of the present invention is represented 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.

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

  A developer for evaluation was produced by mixing 20 parts by mass of the toner and 200 parts by mass of a 45 μm ferrite carrier coated with a styrene-methacrylate copolymer. The toner used for the developer was used as the toner for the actual image.

(Evaluation criteria)
《Occurrence of hollows》
The presence or absence of missing characters in every 10,000 continuous prints was visually observed with the letter “a”.

Evaluation criteria: ○: No omission occurs on all 100,000 sheets. △: Occurrence of omissions after 50,000 sheets, but no minor occurrences after 50,000 sheets. X: From initial to 50,000 sheets. There is an occurrence of hollowing out, or there is no occurrence of up to 50,000 sheets from the beginning, but there is no minor hollowing out after 50,000 sheets <Cleaning>
The occurrence of poorly cleaned images through 100,000 copies and the occurrence of toner filming on the photoreceptor after the completion of 100,000 copies were evaluated by visual observation.

○: No image defect and no toner filming on the photoreceptor Δ: No image defect occurs but toner filming occurs on the photoreceptor ×: Image defect occurs << Photosensitive film thickness Amount of wear
The amount of wear was determined by obtaining the difference in the average film thickness of the photosensitive layer measured at the start of evaluation of live-action and at the end of copying 100,000 sheets.

Film thickness measurement method The film thickness of the photosensitive layer is measured at 10 points at random in the uniform film thickness portion, and the average value is taken as the film thickness of the photosensitive layer. The film thickness measuring device is an eddy current film thickness measuring device EDDY560C (manufactured by HELMUT FISCHER GMBTE CO), and the difference in the photosensitive layer thickness before and after the actual shooting test is defined as the film thickness depletion amount.

<Transfer rate>
The transfer rate was evaluated using a multifunction machine modified so that the residual toner could be collected. The transfer rate was obtained by calculating the amount of residual toner when the toner adhesion amount of a character image having a pixel rate of 5% (A4 size) was set to 20.00 mg per print, and calculating from that value. The smaller the transfer residual toner, the higher the transfer rate, the deterioration of the developer is suppressed, and a high density image is obtained, which is preferable.

  First, a surface layer is necessary to improve the transfer rate, but in the surface layer other than the present invention, there is a problem of hollowing out and cleaning properties, whereas an electrophotographic photoreceptor having the surface layer of the present invention. Those using the are excellent in all of the evaluations of character image quality (middle defect), photoreceptor film thickness wear amount, transfer rate, and cleaning properties.

It is a figure which shows the cross section of the developing device of the counter direction developing method. 1 is a diagram illustrating an example of a schematic configuration of an electrophotographic apparatus having a process cartridge including a photoreceptor. 1 is a cross-sectional configuration diagram of a color image forming apparatus showing an embodiment of the present invention. 1 is a sectional view of a color image forming apparatus using an electrophotographic photosensitive member of the present invention. It is a measurement graph of resistance generated by cutting resistance. It is a figure which shows an example of the dispersion processing apparatus which circulates the liquid collision dispersion | distribution process and filtration process under high pressure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoconductor C axis | shaft 2 Charging means 3 Exposure light 4 Developing means 5 Transfer means P Transfer material 24 Fixing means 6 Cleaning means Pex Pre-exposure means PC Process cartridge container AN Guide means 101 Organic photoreceptor 102 Developing device 110 Developing container 118 Supply port 120 Developing Sleeve 121 Magnet 122 Developing Blade 123 First Conveying Member 124 Second Conveying Member 128 Screw Blade 130 Plate-like Projection 140 Bulkhead N1 Developing Magnetic Magnetic Field N2 Second Developing Magnetic Magnetic Field S1 Pumping Magnetic Field S2 Third Conveying Magnetic Field S3 First Conveying Magnetic Field P1 Development Agent drop position Q1 Pumping position

Claims (10)

In an electrophotographic photosensitive member having a photosensitive layer on a support, when the surface layer of the electrophotographic photosensitive member contains fine particles having lubricity and the surface layer is continuously scratched with a needle, the surface layer When the fluctuation value of the resistance value (mN) generated between the needle and the needle is expressed by the following formula (1), the physical properties of the surface layer are configured to satisfy the following formula (2). An electrophotographic photoreceptor.
Formula (1)
T = X ₁ ² + X ₂ ² ... + X ₂₄ ²
_{M = (X 1 + X 2} ····· + X 24) 2/24
N = [{(X ₁ + X ₃ ... + X ₂₃ ) ² + (X ₂ + X ₄ ... + X ₂₄ ) ² } / 12] −M
E = (TMN) / 22
X ₁ : Maximum resistance value for 0 to 5 seconds X ₂ : Minimum resistance value for 0 to 5 seconds X ₃ : Maximum resistance value for 5 to 10 seconds X ₄ : Resistance value for 5 to 10 seconds minimum value X _5: the maximum of the resistance value of 5 to 15 seconds X _6: minimum value of the resistance values of 5 to 15 seconds X _7: maximum resistance of 15 to 20 seconds X _8: 15-20 seconds resistance Minimum value
・
・
X ₂₃ : Maximum value of resistance value for 55 to 60 seconds X ₂₄ : Minimum value of resistance value for 55 to 60 seconds (The unit of Xn is mN)
Formula (2)
1.0 ≦ S ≦ 10.0
However,
S = 10 log {(ME) / 24E} In an electrophotographic photosensitive member having a photosensitive layer on a support, when the surface layer of the electrophotographic photosensitive member contains fine particles having lubricity and the surface layer is continuously scratched with a needle, the surface layer An electrophotography characterized in that the physical properties of the surface layer satisfy the following formula (3) when the fluctuation value of the resistance value generated between the needle and the needle is represented by the following formula (1): Photoconductor.
Formula (1)
T = X ₁ ² + X ₂ ² ... + X ₂₄ ²
_{M = (X 1 + X 2} ····· + X 24) 2/24
N = [{(X ₁ + X ₃ ... + X ₂₃ ) ² + (X ₂ + X ₄ ... + X ₂₄ ) ² } / 12] −M
E = (TMN) / 22
X ₁ : Maximum resistance value for 0 to 5 seconds X ₂ : Minimum resistance value for 0 to 5 seconds X ₃ : Maximum resistance value for 5 to 10 seconds X ₄ : Resistance value for 5 to 10 seconds minimum value X _5: the maximum of the resistance value of 5 to 15 seconds X _6: minimum value of the resistance values of 5 to 15 seconds X _7: maximum resistance of 15 to 20 seconds X _8: 15-20 seconds resistance Minimum value
・
・
X ₂₃ : Maximum value of resistance value for 55 to 60 seconds X ₂₄ : Minimum value of resistance value for 55 to 60 seconds (The unit of Xn is mN)
Formula (3)
20.0 ≦ K ≦ 45.0
However, K is represented by the following formula.
K = 10 log {(ME) / 24} The electrophotographic photosensitive member according to claim 1 or 2, wherein the proportion of the fine particles in the surface layer is 5% by mass to 30% by mass. The electrophotographic photosensitive member according to claim 1, wherein an average primary particle size of the fine particles is in a range of 0.01 to 0.3 μm. The electrophotographic photoreceptor according to claim 1, wherein the fine particles contain silicon atoms. The electrophotographic photosensitive member according to claim 1, wherein the fine particles contain a fluorine atom. The electrophotographic apparatus according to any one of claims 1 to 6, wherein the photosensitive layer comprises a layer containing at least a charge generating substance and a charge transporting substance, and a protective layer laminated thereon. Photoconductor. An electrophotographic image forming apparatus having a photosensitive member and at least charging, image exposing, developing, and transferring means, wherein the photosensitive member is the electrophotographic photosensitive member according to any one of claims 1 to 7. An electrophotographic image forming apparatus. The electrophotographic photosensitive member according to claim 1, wherein the photosensitive member is an electrophotographic image forming method in which an image is obtained by at least charging, image exposure, development and transfer on a photosensitive member. An electrophotographic image forming method characterized by the above. A process cartridge for use in an electrophotographic image forming apparatus having a photosensitive member and at least charging, image exposure, development, and transfer means, and the electrophotographic photosensitive member according to any one of claims 1 to 7, It has at least one of a charging device, an image exposure device, a developing device, a cleaning device, and a slow current device, and is designed to be freely inserted into and removed from the electrophotographic image forming apparatus. Process cartridge.

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