JP2007334327A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus forming an image of high quality with high resolution and high gradation and an image with low fog and less defect. <P>SOLUTION: The image forming apparatus has an electrophotographic photoreceptor comprising an under coat layer containing a binder resin and metal oxide particles on a conductive support and a photosensitive layer formed on the under coat layer: In a liquid obtained by dispersing the under coat layer in a solvent prepared by mixing methanol and propanol in a weight ratio of 7:3, the metal oxide particles in the liquid have a volume average particle diameter of not more than 0.1 μm and a cumulative 90% particle diameter of not more than 0.3 μm from the smaller diameter side, measured by a dynamic light scattering method. A latent image formed on the above electrophotographic photoreceptor is developed with a toner having an average circularity of 0.940 to 1.000 measured by a flow type particle image analyzer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus using an electrophotographic photosensitive member having an undercoat layer. More specifically, the present invention relates to an image forming apparatus capable of forming a high-quality image that achieves both high resolution and low fog.

  In recent years, electrophotographic technology has been widely used and applied not only in the field of copying machines but also in the field of various printers because of its immediacy and high-quality images. For photoconductors that are the core of electrophotographic technology, organic photoconductive materials that use organic photoconductive materials that have advantages such as pollution-free and easy manufacturing compared to inorganic photoconductive materials. The body has been developed. Usually, the organic photoreceptor is formed by forming a photosensitive layer on a conductive support, and has a single-layer photosensitive layer in which a photoconductive material is dissolved or dispersed in a binder resin; A so-called multilayer photoreceptor having a charge generation layer containing a charge generation material and a photosensitive layer composed of a plurality of layers formed by laminating a charge transport layer containing a charge transport material is known.

  In organic photoreceptors, various defects such as fog, black spots, and color spots are observed in images formed using the photoreceptor due to changes in the usage environment of the photoreceptor and changes in electrical characteristics due to repeated use. In order to stably form a good image, a method of providing an undercoat layer having a binder resin and titanium oxide particles between a conductive substrate and a photosensitive layer is known (for example, see Patent Document 1). ).

  The layer of the organic photoreceptor is usually formed by applying and drying a coating solution in which materials are dissolved or dispersed in various solvents because of its high productivity, and contains titanium oxide particles and a binder resin. In the undercoat layer, since the titanium oxide particles and the binder resin are present in an incompatible state in the undercoat layer, the undercoat layer forming coating solution is formed by applying a coating solution in which titanium oxide particles are dispersed. The

  Conventionally, such a coating liquid is produced by wet-dispersing titanium oxide particles in an organic solvent with a known mechanical grinding device such as a ball mill, a sand grind mill, a planetary mill, or a roll mill for a long time. It was common (see, for example, Patent Document 1). When the titanium oxide particles in the coating solution for forming the undercoat layer are dispersed using a dispersion medium, the material of the dispersion medium is made of titania or zirconia, so that an electron having excellent charge exposure repeatability even under low temperature and low humidity conditions. It is disclosed that a photographic photoreceptor can be provided (see, for example, Patent Document 2).

Further, in the copying machine and printer, in addition to the stability in image formation with few image defects, higher image quality such as higher resolution and higher gradation performance is required. In order to achieve this, a toner having an average particle size of about 3 to 8 μm and a narrow particle size distribution has been used.
Conventionally, toners are mainly produced by a melt-kneading pulverization method in which a binder resin and a colorant are melt-kneaded until uniform and then pulverized. However, in the melt-kneading pulverization method, it is difficult to efficiently produce a toner that can cope with high image quality.

  Therefore, a so-called polymerization toner that generates toner particles in an aqueous medium has been proposed. For example, Patent Document 3 below discloses a suspension polymerization toner. Patent Document 4 listed below discloses an emulsion polymerization aggregation toner. In particular, the emulsion polymerization aggregation method is a method of producing a toner by aggregating polymer resin fine particles and a colorant in a liquid medium, and the toner particle diameter and circularity can be adjusted by controlling the aggregation conditions. Therefore, there is an advantage that various performances required for the toner can be easily optimized.

  In order to improve releasability, low-temperature fixability, high-temperature offset resistance, filming resistance, and the like, a method in which a toner contains a low softening point substance (so-called wax) has been proposed. In the melt-kneading pulverization method, it is difficult to increase the amount of wax contained in the toner, and the limit is about 5% with respect to the binder resin. On the other hand, as described in Patent Documents 3 and 4, the polymerized toner can contain a large amount (5 to 30%) of a low softening point substance.

However, when an image is formed using the toner as described above, the image quality is high and the fogging phenomenon of the image is easily developed. Therefore, high resolution and high gradation performance and low fog are compatible at a high level. It was difficult to do.
Japanese Patent Laid-Open No. 11-202519 Japanese Patent Laid-Open No. 6-273963 JP-A-5-88409 JP-A-11-143125

  The present invention solves such a problem. That is, an object of the present invention is to provide an image forming apparatus capable of forming a high-quality image that simultaneously achieves a high-quality image with high resolution and high gradation and an image with low fog and few defects. There is.

  The present inventors have intensively studied a method and an image forming apparatus for forming a high-quality image that simultaneously achieves a high-quality image having high resolution and high gradation and an image with low fog and few defects. As a result, it has been found that a high-quality image can be obtained by developing with a specific toner using an electrophotographic photosensitive member having a specific undercoat layer, and the present invention has been completed.

  That is, the gist of the present invention is as follows: (1) an electrophotographic photosensitive member, a charging means for charging the electrophotographic photosensitive member, and an image that forms an electrostatic latent image by performing image exposure on the charged electrophotographic photosensitive member. In an image forming apparatus having an exposure unit, a developing unit that develops the formed electrostatic latent image with toner, and a transfer unit that transfers the toner to a transfer target, the electrophotographic photosensitive member is placed on a conductive support. The undercoat layer containing the binder resin and the metal oxide particles, and the photosensitive layer formed on the layer, and the undercoat layer was mixed with methanol and 1-propanol at a weight ratio of 7: 3. The volume average particle size of the metal oxide particles in the liquid dispersed in the solvent measured by the dynamic light scattering method is 0.1 μm or less, and the cumulative 90% particle size accumulated from the small particle size side is 0. .3 μm or less and the flow type particle image of the toner The image forming apparatus is characterized in that the average circularity measured by the analyzer is 0.940 or more and 1.000 or less. At this time, preferably (2) the toner is a toner produced in an aqueous medium, preferably (3) the toner is a toner having a resin coating layer, or (4) a toner containing paraffin wax. In particular, (5) the resin coating layer preferably contains a polysiloxane wax.

  According to the present invention, a high-quality image typified by high resolution, high gradation and the like, and an image with few defects typified by low fog, etc., can be obtained simultaneously. It is possible to provide an image forming apparatus that can be formed.

Hereinafter, embodiments of the present invention will be described in detail. However, the description of the constituent elements described below is a representative example of the embodiments of the present invention, and is appropriately modified and implemented without departing from the spirit of the present invention. can do.
The present invention relates to an image forming apparatus including an electrophotographic photosensitive member having a specific undercoat layer.

  The electrophotographic photoreceptor according to the present invention has an undercoat layer and a photosensitive layer on a conductive support. The undercoat layer according to the present invention is provided between the conductive support and the photosensitive layer, improves the adhesion between the conductive support and the photosensitive layer, conceals dirt and scratches on the conductive support, Functions such as prevention of carrier injection due to non-uniformity of impurities and surface physical properties, improvement of non-uniformity of electrical characteristics, prevention of lowering of surface potential due to repeated use, prevention of local surface potential fluctuations that cause image quality defects, etc. It is a layer which has at least one and is not essential for the development of photoelectric characteristics.

<Electrophotographic photoreceptor>
The electrophotographic photosensitive member used in the image forming apparatus of the present invention is not particularly limited in its detailed configuration as long as a specific undercoat layer is provided on a conductive support. A typical configuration will be described below.
<Conductive support>
As the conductive support used for the photoreceptor, for example, metal materials such as aluminum, aluminum alloy, stainless steel, copper, and nickel, and conductive powders such as metal, carbon, and tin oxide are added to impart conductivity. A resin material, a resin, glass, paper, or the like on which a conductive material such as aluminum, nickel, or ITO (indium tin oxide) is deposited or applied on the surface is mainly used. As a form, a drum shape, a sheet shape, a belt shape or the like is used. A conductive support having a suitable resistance value may be applied to a conductive support made of a metal material in order to control conductivity, surface properties, etc., or to cover defects.
When a metal material such as an aluminum alloy is used as the conductive support, it may be used after an anodized film is applied. When an anodized film is applied, it is desirable to perform a sealing treatment by a known method.
For example, an anodic oxidation film is formed by anodizing in an acidic bath such as chromic acid, sulfuric acid, oxalic acid, boric acid, sulfamic acid, etc. give. In the case of anodic oxidation in sulfuric acid, the sulfuric acid concentration is 100 to 300 g / l, the dissolved aluminum concentration is 2 to 15 g / l, the liquid temperature is 15 to 30 ° C., the electrolysis voltage is 10 to 20 V, and the current density is 0.5 to Although it is preferable to set within the range of ² A / dm ² , it is not limited to the above conditions.

It is preferable to perform a sealing treatment on the anodic oxide film thus formed. The sealing treatment may be performed by a known method. For example, it is immersed in an aqueous solution containing nickel fluoride as a main component, or immersed in an aqueous solution containing nickel acetate as a main component. A high temperature sealing treatment is preferably performed.
The concentration of the nickel fluoride aqueous solution used in the case of the low-temperature sealing treatment can be appropriately selected, but more preferable results can be obtained when it is used in the range of 3 to 6 g / l. Moreover, in order to advance a sealing process smoothly, as processing temperature, it is 25-40 degreeC, Preferably it is 30-35 degreeC, Moreover, nickel fluoride aqueous solution pH is 4.5-6.5, Preferably it is 5 It is better to process in the range of .5 to 6.0. As the pH adjuster, oxalic acid, boric acid, formic acid, acetic acid, sodium hydroxide, sodium acetate, aqueous ammonia and the like can be used. The treatment time is preferably in the range of 1 to 3 minutes per 1 μm of film thickness. In order to further improve the physical properties of the film, cobalt fluoride, cobalt acetate, nickel sulfate, a surfactant or the like may be added to the nickel fluoride aqueous solution. Subsequently, it is washed with water and dried to finish the low temperature sealing treatment. As the sealing agent in the case of the high-temperature sealing treatment, an aqueous solution of a metal salt such as nickel acetate, cobalt acetate, lead acetate, nickel acetate-cobalt, and barium nitrate can be used, and it is particularly preferable to use nickel acetate. . The concentration in the case of using an aqueous nickel acetate solution is preferably 5 to 20 g / l. The treatment temperature is 80 to 100 ° C., preferably 90 to 98 ° C., and the pH of the nickel acetate aqueous solution is preferably 5.0 to 6.0. Here, ammonia water, sodium acetate, or the like can be used as the pH adjuster. The treatment time is 10 minutes or longer, preferably 20 minutes or longer. In this case as well, sodium acetate, organic carboxylic acid, anionic and nonionic surfactants may be added to the nickel acetate aqueous solution in order to improve the film properties. Subsequently, it is washed with water and dried to finish the high temperature sealing treatment. When the average film thickness is thick, stronger sealing conditions are required due to the higher concentration of the sealing liquid and high temperature / long-time treatment. Accordingly, productivity is deteriorated and surface defects such as spots, dirt, and dusting are likely to occur on the coating surface. From such a point, it is preferable that the average film thickness of the anodic oxide coating is usually 20 μm or less, particularly 7 μm or less.

  The support surface may be smooth, or may be roughened by using a special cutting method or polishing. Further, it may be roughened by mixing particles having an appropriate particle diameter with the material constituting the support. In order to reduce the cost, it is possible to use the drawing tube as it is without cutting. Especially when using non-cutting aluminum supports such as drawing, impact processing, ironing, etc., the process eliminates dirt, foreign matter, etc. on the surface, small scratches, etc., and a uniform and clean support can be obtained. Therefore, it is preferable.

<Underlayer>
The undercoat layer is a layer containing a binder resin and metal oxide particles. The undercoat layer may contain other components as long as the effects of the present invention are not significantly impaired.
In the electrophotographic photoreceptor according to the present invention, the undercoat layer is measured by a dynamic light scattering method in a liquid in which methanol and 1-propanol are mixed in a solvent in which the weight ratio is 7: 3. The volume average particle diameter of the metal oxide particles is 0.1 μm or less, preferably 95 nm or less, more preferably 90 nm or less. Although there is no restriction | limiting in particular in the minimum of a volume average particle diameter, Usually, it is 20 nm or more. By satisfying the above range, the electrophotographic photosensitive member of the present invention has stable exposure-charging repetition characteristics under low temperature and low humidity, and suppresses occurrence of image defects such as black spots and color spots in the obtained image. it can.

  Similarly, the cumulative 90% particle diameter accumulated from the small particle diameter side of the metal oxide particles is 0.3 μm or less, preferably 0.2 μm or less, more preferably 0.15 μm or less. In a conventional electrophotographic photoreceptor, the undercoat layer contains metal oxide particles that are large enough to penetrate the front and back of the undercoat layer in some cases, and the large metal oxide particles may cause defects during image formation. It was. Further, when a contact type is used as the charging means, when the photosensitive layer is charged, the charge moves from the conductive substrate to the photosensitive layer through the metal oxide particles so that the charging is appropriately performed. There was also a risk that it would be impossible. However, in the electrophotographic photosensitive member of the present invention, since the cumulative 90% particle diameter is very small, there are very few large metal oxide particles that cause defects as described above. As a result, in the electrophotographic photoreceptor of the present invention, it is possible to suppress the occurrence of defects and the inability to appropriately charge, and high-quality image formation is possible.

Furthermore, using an electrophotographic photosensitive member having an undercoat layer satisfying both the above conditions, an average circularity measured by a flow type particle image analyzer of a latent image formed on the electrophotographic photosensitive member is 0. High quality images can be formed by developing with a toner of 940 to 1.000.
The volume average particle size in the present invention is a particle at the point (μm) at which the curve becomes 50% when the volume particle size distribution cumulative curve is obtained from the small particle size side with the total volume of one powder group as 100%. It is the diameter, meaning the central diameter (Median diameter), and the cumulative 90% particle diameter is the point (μm) at which the curve becomes 90% when the volume particle size distribution cumulative curve is similarly determined from the small particle diameter side. The particle size.

  The metal oxide particles in the undercoat layer according to the present invention are preferably present as primary particles. However, there are few such cases, and in most cases, they are aggregated to exist as aggregate secondary particles, or both are mixed. Therefore, how the size distribution of the metal oxide particles in the undercoat layer should be very important. Although it is very difficult to directly evaluate the particle size distribution of the metal oxide particles in the undercoat layer, by dispersing the undercoat layer in a specific solvent and evaluating the dispersion, The particle size distribution of the metal oxide particles can be known.

  The volume average particle diameter of the metal oxide particles measured by the dynamic light scattering method is 0 in a liquid in which the undercoat layer is dispersed in a solvent in which methanol and 1-propanol are mixed at a weight ratio of 7: 3. In the image forming apparatus provided with the electrophotographic photosensitive member having the undercoat layer, the cumulative 90% particle diameter accumulated from the small particle diameter side is 0.3 μm or less. Even if an image is formed using a toner having a specific circularity, a high-quality image in which fog is hardly generated can be obtained.

According to the present invention, the undercoat layer is accumulated from the volume average particle diameter and the small particle diameter side of the metal oxide particles in a liquid in which methanol and 1-propanol are mixed in a solvent in a weight ratio of 7: 3. As the cumulative 90% particle diameter, the value measured by the dynamic light scattering method is used regardless of the existence form of the metal oxide particles.
In the dynamic light scattering method, the speed of Brownian motion of finely dispersed particles is detected, and the particle size distribution is detected by irradiating the particles with laser light and detecting light scattering (Doppler shift) with different phases according to the speed. Is what you want. The value of the volume average particle diameter of the metal oxide particles in the undercoat layer according to the present invention is that the metal oxide particles are stably dispersed in a solvent in which methanol and 1-propanol are mixed at a weight ratio of 7: 3. It does not mean the particle size of metal oxide particles or the like as powder before dispersion. In actual measurement, a dynamic light scattering particle size analyzer (MICROTRAC UPA model: 9340-UPA, hereinafter abbreviated as UPA) manufactured by Nikkiso Co., Ltd. is used with the following settings. A specific measurement operation is performed based on the instruction manual of the particle size analyzer (manufactured by Nikkiso Co., Ltd., Document No. T15-490A00, revised No. E).

・ Setting of dynamic light scattering system particle size analyzer Upper limit of measurement: 5.9978 μm
Measurement lower limit: 0.0035 μm
Number of channels: 44
Measurement time: 300 sec.
Measurement temperature: 25 ° C
Particle permeability: Absorption Particle refractive index: N / A (not applicable)
Particle shape: non-spherical density: 4.20 (g / cm ³ ) (*)
Dispersion medium type: Mixed solvent of methanol and 1-propanol (weight ratio: methanol / 1-propanol = 7/3)
Dispersion medium refractive index: 1.35
(*) The value of density is for titanium dioxide particles, and for other particles, the values described in the instruction manual are used.
In addition, when the liquid which disperse | distributed the undercoat layer to the solvent which mixed methanol and 1-propanol by the weight ratio of 7: 3 is too thick, and the density | concentration is outside the measurable range of a measuring device. The coating solution for forming the undercoat layer is diluted with a mixed solvent of methanol and 1-propanol (methanol / 1-propanol = 7/3 (weight ratio); refractive index = 1.35), and the concentration is measured by the measuring device. Try to be within the possible range. For example, in the case of the above UPA, the sample is diluted with a mixed solvent of methanol and 1-propanol so that the sample concentration index (SIGNAL LEVEL) suitable for measurement is 0.6 to 0.8.

  Even if the dilution is performed in this way, it is considered that the particle diameter of the metal oxide particles in the liquid in which the undercoat layer is dispersed does not change. Therefore, the volume average particle diameter measured as a result of the dilution is measured. , And the cumulative 90% particle size is measured in a liquid in which the undercoat layer is dispersed in a solvent in which methanol and 1-propanol are mixed at a weight ratio of 7: 3 according to the present invention, and The cumulative 90% particle size shall be handled.

<Metal oxide particles>
As the metal oxide particles contained in the undercoat layer according to the present invention, any metal oxide particles that can be used for an electrophotographic photoreceptor can be used.
Specific examples of metal oxides forming the metal oxide particles include metal oxides containing one metal element such as titanium oxide, aluminum oxide, silicon oxide, zirconium oxide, zinc oxide and iron oxide; calcium titanate And metal oxides containing a plurality of metal elements such as strontium titanate and barium titanate. Among these, metal oxide particles made of a metal oxide having a band gap of 2 to 4 eV are preferable. If the band gap is too small, carrier injection from the conductive support is likely to occur, and defects such as black spots and color spots are likely to occur when an image is formed. If the band gap is too large, electron trapping occurs. This is because charge transfer is hindered and electrical characteristics may be deteriorated.

As the metal oxide particles, only one type of particles may be used, or a plurality of types of particles may be used in any combination and ratio. In addition, the metal oxide particles may be formed from only one kind of metal oxide, or may be formed by using two or more kinds of metal oxides in any combination and ratio. good.
Among the metal oxides forming the metal oxide particles, titanium oxide, aluminum oxide, silicon oxide and zinc oxide are preferable, titanium oxide and aluminum oxide are more preferable, and titanium oxide is particularly preferable.

  The crystal form of the metal oxide particles is arbitrary as long as the effects of the present invention are not significantly impaired. For example, the crystal form of metal oxide particles using titanium oxide as a metal oxide (that is, titanium oxide particles) is not limited, and any of rutile, anatase, brookite, and amorphous can be used. Further, the crystal form of the titanium oxide particles may include those in a plurality of crystal states from those having different crystal states.

Further, the surface of the metal oxide particles may be subjected to various surface treatments. For example, treatment with a treating agent such as an inorganic substance such as tin oxide, aluminum oxide, antimony oxide, zirconium oxide, or silicon oxide, or an organic substance such as stearic acid, polyol, or organic silicon compound may be performed.
In particular, when titanium oxide particles are used as the metal oxide particles, the surface treatment is preferably performed with an organosilicon compound. Examples of the organosilicon compound include silicone oils such as dimethylpolysiloxane and methylhydrogenpolysiloxane; organosilanes such as methyldimethoxysilane and diphenyldimethoxysilane; silazanes such as hexamethyldisilazane; vinyltrimethoxysilane and γ-mercaptopropyl. Examples thereof include silane coupling agents such as trimethoxysilane and γ-aminopropyltriethoxysilane.

  The metal oxide particles are particularly preferably treated with a silane treating agent represented by the structure of the following formula (i). This silane treatment agent is a good treatment agent with good reactivity with metal oxide particles.

In the formula (i), R ¹ and R ² each independently represents an alkyl group. The number of carbon atoms of R ¹ and R ² is not limited, but is usually 1 or more and usually 18 or less, preferably 10 or less, more preferably 6 or less, and particularly 3 or less. Thereby, the advantage that the reactivity with a metal oxide particle becomes suitable is acquired. If the number of carbon atoms is too large, the reactivity with the metal oxide particles may be decreased, and the dispersion stability of the treated metal oxide particles in the coating solution may be decreased, which may not be preferable.

Examples of suitable ones of R ¹ and R ² include methyl group, ethyl group, propyl group and the like.
In the formula (i), R ³ represents an alkyl group or an alkoxy group. The carbon number of R ³ is not limited, but is usually 1 or more and usually 18 or less, preferably 10 or less, more preferably 6 or less, and particularly 3 or less. Thereby, the advantage that the reactivity with a metal oxide particle becomes suitable is acquired. If the number of carbon atoms is too large, the reactivity with the metal oxide particles may be decreased, and the dispersion stability of the treated metal oxide particles in the coating solution may be decreased, which may not be preferable.

Examples of suitable R ³ include methyl group, ethyl group, methoxy group, and ethoxy group. In addition, the outermost surface of these surface-treated metal oxide particles is usually treated with the treatment agent as described above. At this time, the surface treatment described above may be performed only by one surface treatment, or two or more surface treatments may be performed in any combination. For example, it may be treated with a treatment agent such as aluminum oxide, silicon oxide or zirconium oxide before the surface treatment with the silane treatment agent represented by the formula (i). Moreover, you may use together the metal oxide particle which performed different surface treatment in arbitrary combinations and a ratio.

Among the metal oxide particles according to the present invention, examples of those that have been commercialized will be given. However, the metal oxide particles according to the present invention are not limited to the products exemplified below.
Examples of specific products of titanium oxide particles include ultrafine titanium oxide “TTO-55 (N)” that has not been surface-treated; ultrafine titanium oxide “TTO-55 (A) coated with Al ₂ O _3. ) ”,“ TTO-55 (B) ”; ultrafine titanium oxide surface treated with stearic acid“ TTO-55 (C) ”; ultrafine titanium oxide surface treated with Al ₂ O ₃ and organosiloxane “TTO-55 (S)”; high purity titanium oxide “CR-EL”; sulfuric acid method titanium oxide “R-550”, “R-580”, “R-630”, “R-670”, “R-” 680 "," R-780 "," A-100 "," A-220 "," W-10 "; chlorinated titanium oxides" CR-50 "," CR-58 "," CR-60 "," CR-60-2 "," CR-67 "; conductive titanium oxide" SN " -100P "," SN-100D "," ET-300W "; (above, manufactured by Ishihara Sangyo Co., Ltd.). In addition, titanium oxides such as “R-60”, “A-110”, and “A-150”; and “SR-1”, “R-GL”, “R—” coated with Al ₂ O ₃ 5N "," R-5N-2 "," R-52N "," RK-1 "," a-SP "; subjected to SiO _2, Al ₂ O ₃ coating" R-GX "," R-7E _{"; ZnO, SiO 2, Al 2} O 3 coating was subjected to a" R-650 "; subjected to ZrO _2, Al ₂ O ₃ coating" R-61N "; (or, manufactured by Sakai Chemical Industry Co., Ltd.) also like Can be mentioned. Furthermore, surface-treated with SiO _2, Al ₂ O ₃ "TR-700"; ZnO, surface-treated with SiO _2, Al ₂ O ₃ "TR-840", another "TA-500", "TA Surface-untreated titanium oxide such as “-100”, “TA-200”, “TA-300”; “TA-400” (manufactured by Fuji Titanium Industry Co., Ltd.); surface-treated with Al ₂ O ₃ ; surface not subjected to treatment, "MT-150 W", "MT-500B"; surface-treated with SiO _2, Al ₂ O ₃ "MT-100SA", "MT-500SA"; SiO _2, Al ₂ O ₃ and organosiloxane Examples thereof include “MT-100SAS” and “MT-500SAS” (manufactured by Teika Co., Ltd.) surface-treated with siloxane. Examples of specific products of aluminum oxide particles include “Aluminium Oxide C” (manufactured by Nippon Aerosil Co., Ltd.).

Furthermore, examples of specific products of silicon oxide particles include “200CF”, “R972” (manufactured by Nippon Aerosil Co., Ltd.), “KEP-30” (manufactured by Nippon Shokubai Co., Ltd.), and the like.
Moreover, "SN-100P" (made by Ishihara Sangyo Co., Ltd.) etc. are mentioned as an example of the specific goods of a tin oxide particle.
Furthermore, “MZ-305S” (manufactured by Teika Co., Ltd.) and the like are listed as examples of specific products of zinc oxide particles.
<Other physical properties>
There is no restriction | limiting in the average primary particle diameter of the metal oxide particle concerning this invention, and it is arbitrary unless the effect of this invention is impaired remarkably. However, the average primary particle diameter of the metal oxide particles according to the present invention is usually 1 nm or more, preferably 5 nm or more, and usually 100 nm or less, preferably 70 nm or less, more preferably 50 nm or less.

The average primary particle diameter can be obtained by an arithmetic average value of particle diameters directly observed with a transmission electron microscope (hereinafter referred to as “TEM” as appropriate).
Moreover, there is no restriction | limiting in the refractive index of the metal oxide particle which concerns on this invention, What kind of thing can be used if it can be used for an electrophotographic photoreceptor. The refractive index of the metal oxide particles according to the present invention is usually 1.3 or more, preferably 1.4 or more, more preferably 1.5 or more, and usually 3.0 or less, preferably 2.9 or less, more Preferably it is 2.8 or less.

  In addition, the literature value described in various publications can be used for the refractive index of a metal oxide particle. For example, according to the filler utilization dictionary (Filler Study Group, Taiseisha, 1994), it is as shown in Table 1 below.

  In the coating liquid for forming the undercoat layer of the present invention, the use ratio of the metal oxide particles and the binder resin is arbitrary as long as the effects of the present invention are not significantly impaired. However, in the coating liquid for forming the undercoat layer of the present invention, the metal oxide particles are usually 0.5 parts by weight or more, preferably 0.7 parts by weight or more, with respect to 1 part by weight of the binder resin. More preferably 1.0 parts by weight or more, and usually 4 parts by weight or less, preferably 3.8 parts by weight or less, more preferably 3.5 parts by weight or less. If the amount of the metal oxide particles is too small relative to the binder resin, the electric characteristics of the electrophotographic photosensitive member may be deteriorated, and particularly the residual potential may be increased. Moreover, when there are too many metal oxide particles with respect to binder resin, since there exists a possibility that image defects, such as the black spot of a picture formed using the said photoreceptor and a color point, may increase, it is unpreferable.

<Binder resin>
As the binder resin contained in the undercoat layer according to the present invention, any binder resin can be used as long as the effects of the present invention are not significantly impaired. Usually, any binder resin that can be used for an electrophotographic photosensitive member is used. be able to.
Usually, it is soluble in a solvent such as an organic solvent, and the undercoat layer after formation is insoluble or low in solubility in a solvent such as an organic solvent used in a coating solution for forming a photosensitive layer. Use a material that does not substantially mix.
As such a binder resin, for example, a resin such as phenoxy, epoxy, polyvinyl pyrrolidone, polyvinyl alcohol, casein, polyacrylic acid, cellulose, gelatin, starch, polyurethane, polyimide, polyamide or the like is cured alone or with a curing agent. Can be used with. Of these, polyamide resins such as alcohol-soluble copolymerized polyamides and modified polyamides are preferable because they exhibit good dispersibility and coatability.

  As the polyamide resin, for example, so-called copolymer nylon obtained by copolymerizing 6-nylon, 66-nylon, 610-nylon, 11-nylon, 12-nylon, etc .; N-alkoxymethyl-modified nylon, N-alkoxyethyl-modified Examples thereof include alcohol-soluble nylon resins of a type in which nylon is chemically modified, such as nylon. Specific products include, for example, “CM4000”, “CM8000” (manufactured by Toray), “F-30K”, “MF-30”, “EF-30T” (manufactured by Nagase Chemtech Co., Ltd.), and the like. .

  Among these polyamide resins, a copolymerized polyamide resin containing a diamine component corresponding to the diamine represented by the following formula (ii) (hereinafter, appropriately referred to as “diamine component corresponding to formula (ii)”) as a constituent component is particularly preferable. Used.

In the formula (ii), R ^{4 to} R ⁷ represent a hydrogen atom or an organic substituent. m and n each independently represents an integer of 0 to 4. In addition, when there are a plurality of substituents, these substituents may be the same as or different from each other.
When the example of a suitable thing as an organic substituent represented by R < ⁴ > -R < ⁷ > is given, the hydrocarbon group which may contain the hetero atom is mentioned. Among these, preferred are, for example, alkyl groups such as methyl group, ethyl group, n-propyl group and isopropyl group; alkoxy groups such as methoxy group, ethoxy group, n-propoxy group and isopropoxy group; phenyl group and naphthyl group And aryl groups such as an anthryl group and a pyrenyl group, more preferably an alkyl group or an alkoxy group. Particularly preferred are a methyl group and an ethyl group.

Although the carbon number of the organic substituent represented by R ⁴ to R ⁷ are arbitrary unless significantly impairing the effects of the present invention, usually 20 or less, preferably 18 or less, more preferably 12 or less, and usually 1 or more. If the number of carbon atoms is too large, the solubility in the solvent will deteriorate and the coating solution will gel, or even if temporarily dissolved, the coating solution may become cloudy or gel with time, which is not preferable. There is.

  The copolymerized polyamide resin containing a diamine component corresponding to the formula (ii) as a constituent component constitutes a constituent component other than the diamine component corresponding to the formula (ii) (hereinafter simply referred to as “other polyamide constituent component”). It may be included as a unit. Examples of other polyamide constituents include lactams such as γ-butyrolactam, ε-caprolactam, lauryllactam; 1,4-butanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,20-eicosanedicarboxylic acid, and the like. Dicarboxylic acids; diamines such as 1,4-butanediamine, 1,6-hexamethylenediamine, 1,8-octamethylenediamine, 1,12-dodecanediamine; piperazine and the like. At this time, examples of the copolymerized polyamide resin include those obtained by copolymerizing the constituent components into, for example, binary, ternary, and quaternary.

When the copolymerized polyamide resin containing the diamine component corresponding to the formula (ii) as a constituent component contains other polyamide constituent components as constituent units, the proportion of the diamine component corresponding to the formula (ii) in all the constituent components Although there is no limitation, it is usually 5 mol% or more, preferably 10 mol% or more, more preferably 15 mol% or more, and usually 40 mol% or less, preferably 30 mol% or less. If there is too much diamine component corresponding to formula (ii), the stability of the coating solution may be deteriorated. May be unfavorable and may be unfavorable.
Specific examples of the copolymerized polyamide resin are shown below. However, in specific examples, the copolymerization ratio represents the charge ratio (molar ratio) of the monomer.

There is no restriction | limiting in particular in the manufacturing method of said copolyamide, The normal polycondensation method of polyamide is applied suitably. For example, a polycondensation method such as a melt polymerization method, a solution polymerization method, and an interfacial polymerization method can be appropriately applied. In the polymerization, for example, a monobasic acid such as acetic acid or benzoic acid; a monoacid base such as hexylamine or aniline may be contained in the polymerization system as a molecular weight regulator.
In addition, binder resin may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

Moreover, there is no restriction | limiting also in the number average molecular weight of binder resin which concerns on this invention. For example, when a copolymerized polyamide is used as the binder resin, the number average molecular weight of the copolymerized polyamide is usually 10,000 or more, preferably 15000 or more, and usually 50000 or less, preferably 35000 or less. If the number average molecular weight is too small or too large, it is difficult to maintain the uniformity of the undercoat layer.
The content of the binder resin in the coating liquid for forming the undercoat layer of the present invention is arbitrary as long as the effects of the present invention are not significantly impaired. However, the content of the binder resin in the coating solution for forming the undercoat layer of the present invention is usually 0.5% by weight or more, preferably 1% by weight or more, and usually 20% by weight or less, preferably 10%. Use in the range of weight percent or less.

<Other ingredients>
The coating liquid for forming the undercoat layer of the present invention may contain components other than the metal oxide particles, the binder resin, and the solvent described above as long as the effects of the present invention are not significantly impaired. For example, the coating liquid for forming the undercoat layer may contain additives as other components.
Examples of the additive include sodium phosphite, sodium hypophosphite, phosphorous acid, heat stabilizers represented by hypophosphorous acid and hindered phenol, and other polymerization additives. In addition, an additive may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

<Coating solution for forming undercoat layer>
The undercoat layer according to the present invention is a layer containing a binder resin and metal oxide particles. The undercoat layer is obtained by applying and forming a coating solution for forming the undercoat layer. Usually, various physical properties of the undercoat layer are affected by the physical properties of the coating solution for forming the undercoat layer.
The coating liquid for forming the undercoat layer may contain other components in addition to the binder resin and metal oxide particles according to the present invention as long as the effects of the present invention are not significantly impaired. These binder resin, metal oxide particles, and other components are the same as those described in the description of the undercoat layer according to the present invention.
Usually, the coating liquid for forming the undercoat layer is obtained by dissolving or dispersing the components constituting the undercoat layer in a solvent.

<Solvent used in coating solution for forming undercoat layer>
As the solvent (solvent for the undercoat layer) used in the coating solution for forming the undercoat layer of the present invention, any solvent can be used as long as it can dissolve the binder resin according to the present invention. . As this solvent, an organic solvent is usually used. Examples of the solvent include alcohols having 5 or less carbon atoms such as methanol, ethanol, 1-propanol or 2-propanol; chloroform, 1,2-dichloroethane, dichloromethane, trichrene, carbon tetrachloride, 1,2-dichloropropane. Halogenated hydrocarbons such as: Nitrogen-containing organic solvents such as dimethylformamide; Aromatic hydrocarbons such as toluene and xylene.

Moreover, the said solvent may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio. Furthermore, even if it is a solvent that does not dissolve the binder resin according to the present invention alone, it can be used if it can dissolve the binder resin by using a mixed solvent with another solvent (for example, the organic solvent exemplified above). can do. In general, coating unevenness can be reduced by using a mixed solvent.
In the coating liquid for forming the undercoat layer of the present invention, the amount ratio of the solvent and the solid content such as metal oxide particles and binder resin varies depending on the coating method of the coating liquid for forming the undercoat layer. The application method to be applied may be appropriately changed so that a uniform coating film is formed.

<The manufacturing method of the coating liquid for forming an undercoat layer>
There is no restriction | limiting in particular in the manufacturing method of the coating liquid for forming the undercoat layer based on this invention. However, the coating liquid for forming the undercoat layer according to the present invention contains metal oxide particles as described above, and the metal oxide particles are contained in the coating liquid for forming the undercoat layer. Distributed and exists. Therefore, the manufacturing method of the coating liquid for forming the undercoat layer according to the present invention usually has a dispersion step of dispersing the metal oxide particles.

<Dispersion method of metal oxide particles>
In order to disperse the metal oxide particles, for example, a known mechanical grinding device (dispersing device) such as a ball mill, a sand grind mill, a planetary mill, or a roll mill is used. What is necessary is just to carry out wet dispersion in a solvent. In this dispersion step, the metal oxide particles according to the present invention are dispersed, but the undercoat layer formed by applying a coating solution for forming the undercoat layer obtained through the dispersion step is mixed with methanol and 1 When dispersed in a solvent mixed with -propanol at a weight ratio of 7: 3, the volume average particle diameter of the metal oxide particles in the liquid measured by the dynamic light scattering method is 0.1 μm or less. Then, the dispersion is performed such that the cumulative 90% particle diameter accumulated from the small particle diameter side is 0.3 μm or less.
As the dispersion solvent used in the dispersion step, the solvent used in the coating solution for forming the undercoat layer may be used, or other solvents may be used. However, when a solvent other than the solvent used for the coating solution for forming the undercoat layer is used as the dispersion solvent, the metal oxide particles and the solvent used for the coating solution for forming the undercoat layer are mixed or solvent-exchanged after dispersion. In this case, however, it is preferable to carry out the above mixing or solvent exchange while preventing the metal oxide particles from aggregating to have a predetermined particle size distribution.

Among the wet dispersion methods, those using a dispersion medium are particularly preferable.
Any known dispersion device may be used as a dispersion device for dispersion using a dispersion medium. Examples of a dispersing device that disperses using a dispersion medium include a pebble mill, a ball mill, a sand mill, a screen mill, a gap mill, a vibration mill, a paint shaker, and an attritor. Among these, those that can circulate and disperse the metal oxide particles are preferable. In addition, wet stirring ball mills such as a sand mill, a screen mill, and a gap mill are particularly preferable from the viewpoints of dispersion efficiency, fineness of reached particle diameter, ease of continuous operation, and the like. These mills may be either vertical or horizontal. The disc shape of the mill can be any plate type, vertical pin type, horizontal pin type or the like. Preferably, a liquid circulation type sand mill is used.

In addition, these dispersion apparatuses may be implemented by only 1 type, and may be implemented in arbitrary combinations of 2 or more types.
Further, when dispersion is performed using a dispersion medium, the formed undercoat layer is dispersed in a solvent in which methanol and 1-propanol are mixed at a weight ratio of 7: 3. The volume average particle diameter of the metal oxide particles measured by the dynamic light scattering method is 0.1 μm or less, and the cumulative 90% particle diameter accumulated from the small particle diameter side is 0.3 μm or less. It is preferable to use a dispersion medium having a particle size of.

  That is, in the method for producing a coating liquid for forming an undercoat layer of the present invention, when metal oxide particles are dispersed in a wet stirring ball mill, the average particle size is usually 5 μm as a dispersion medium of the wet stirring ball mill. As described above, it is preferable to use a dispersion medium having a thickness of 10 μm or more, usually 200 μm or less, preferably 100 μm or less. A dispersion medium having a small particle size tends to give a uniform dispersion in a short time. However, if the particle size is excessively small, there is a possibility that the mass of the dispersion medium becomes too small to perform efficient dispersion.

  Since the dispersion medium usually has a shape close to a true sphere, for example, the average particle diameter can be obtained by measuring by sieving using a sieve described in JIS Z 8801: 2000 or by image analysis, The density can be measured by the Archimedes method. Specifically, for example, the average particle diameter and sphericity of the dispersion medium can be measured by an image analyzer represented by LUZEX50 manufactured by Nireco Corporation.

Although there is no restriction | limiting in the density of a dispersion medium, A thing of 5.5 g / cm < ³ > or more is used normally, Preferably it is 5.9 g / cm < ³ > or more, More preferably, a thing of 6.0 g / cm < ³ > or more is used. Generally, dispersion using a higher density dispersion medium tends to give a uniform dispersion in a shorter time. The sphericity of the dispersion medium is preferably 1.08 or less, more preferably a dispersion medium having a sphericity of 1.07 or less.

  As the material of the dispersion medium, any known material can be used as long as it is insoluble in the dispersion solvent contained in the slurry and has a specific gravity greater than that of the slurry and does not react with the slurry or alter the slurry. Any distributed media can be used. Examples include steel balls such as chrome balls (ball balls for ball bearings) and carbon balls (carbon steel balls); stainless steel balls; ceramic balls such as silicon nitride balls, silicon carbide, zirconia, and alumina; titanium nitride, carbonitride Examples thereof include a sphere coated with a film of titanium or the like. Among these, ceramic spheres are preferable, and zirconia fired balls are particularly preferable. More specifically, it is particularly preferable to use zirconia fired beads described in Japanese Patent No. 3400836.

Note that only one type of dispersion medium may be used, or two or more types may be used in any combination and ratio.
Further, among the wet stirring ball mills, in particular, a cylindrical stator, a slurry supply port provided at one end of the stator, a slurry discharge port provided at the other end of the stator, and a dispersion medium filled in the stator And a rotor that stirs and mixes the slurry supplied from the supply port, a separator that is connected to the discharge port, separates the dispersion medium and the slurry, and discharges the slurry from the discharge port. .

Here, the slurry contains at least metal oxide particles and a dispersion solvent.
Hereinafter, the configuration of this wet stirring ball mill will be described in detail.
The stator is a cylindrical container having a hollow portion therein, and a slurry supply port is formed at one end and a slurry discharge port is formed at the other end. Furthermore, the inside hollow portion is filled with a dispersion medium, and the metal oxide particles in the slurry are dispersed by the dispersion medium. The slurry is supplied from the supply port into the stator, and the slurry in the stator is discharged from the discharge port to the outside of the stator.

The rotor is provided inside the stator, and stirs and mixes the dispersion medium and the slurry. Note that the rotor type includes, for example, a pin, a disk, an annular type, and any type of rotor may be used.
Furthermore, the separator separates the dispersion medium and the slurry. This separator is provided so as to be connected to the discharge port of the stator. And it is comprised so that the slurry and dispersion medium in a stator may be isolate | separated and a slurry may be sent out of the stator from the discharge port of a stator.

  In addition, the separator used here may be any type of separator, and may be a separator that is separated using a screen, a separator that is separated by the action of centrifugal force, Although the separator may be used in combination, an impeller-type separator that is rotatably provided is preferable. In the impeller type separator, the dispersion medium and the slurry are separated by the action of centrifugal force generated by the rotation of the impeller.

Note that the separator may be rotated integrally with the rotor, or may be rotated independently of the rotor.
Moreover, it is preferable that the wet stirring ball mill is provided with a shaft that serves as a rotating shaft of the separator.
Furthermore, it is preferable that a hollow discharge path communicating with the discharge port is formed at the shaft center of the shaft. That is, the wet stirring ball mill includes at least a cylindrical stator, a slurry supply port provided at one end of the stator, a slurry discharge port provided at the other end of the stator, a dispersion medium filled in the stator, and A rotor that stirs and mixes the slurry supplied from the supply port, and an impeller that is connected to the discharge port and is rotatably provided to separate the dispersion medium and the slurry by the action of centrifugal force and discharge the slurry from the discharge port. It is preferable that the separator is configured to include a type separator and a shaft serving as a rotating shaft of the separator, and a hollow discharge path communicating with the discharge port is formed in the shaft center.

  The discharge passage formed in the shaft communicates the rotation center of the separator and the discharge port of the stator. For this reason, the slurry separated from the dispersion medium by the separator is sent to the discharge port through the discharge path, and discharged from the discharge port to the outside of the stator. At this time, although the discharge passage passes through the shaft center, the centrifugal force does not act on the shaft, so that the slurry is discharged without kinetic energy. For this reason, kinetic energy is not wasted and useless power is not consumed.

Such a wet stirring ball mill may be horizontally oriented, but is preferably oriented vertically to increase the filling rate of the dispersion medium. At this time, the discharge port is preferably provided at the upper end of the mill. Further, in this case, it is desirable that the separator is also provided above the dispersion medium filling level.
When the discharge port is provided at the upper end of the mill, the supply port is provided at the bottom of the mill. In this case, as a more preferable aspect, the supply port is configured by a valve seat, and a V-shaped, trapezoidal, or cone-shaped valve body that is fitted to the valve seat so as to be movable up and down and can be in line contact with the edge of the valve seat. To do. This makes it possible to form an annular slit between the edge of the valve seat and the valve body so that the dispersion medium cannot pass through. Therefore, the slurry is supplied at the supply port, but the dispersion medium can be prevented from falling. Further, it is possible to widen the slit to raise the valve body and discharge the dispersion medium, or to lower the valve body to close the slit and seal the mill. Furthermore, since the slit is formed by the edge of the valve body and the valve seat, the coarse particles (metal oxide particles) in the slurry are difficult to bite, and even if they are bitten, they easily come out vertically and are not easily clogged.

  Further, if the valve body is caused to vibrate up and down by the vibration means, the coarse particles caught in the slit can be pulled out from the slit, and the biting itself is difficult to occur. In addition, the shearing force is applied to the slurry by the vibration of the valve body, the viscosity is lowered, and the amount of slurry passing through the slit (that is, the supply amount) can be increased. There is no limitation on the vibration means for vibrating the valve body. For example, in addition to mechanical means such as a vibrator, means for changing the pressure of compressed air acting on a piston integrated with the valve body, for example, a reciprocating compressor In addition, an electromagnetic switching valve for switching intake / exhaust of compressed air can be used.

In such a wet stirring ball mill, it is desirable that a screen for separating the dispersion medium and a slurry outlet are provided at the bottom so that the slurry remaining in the wet stirring ball mill can be taken out after the dispersion is completed.
Further, the wet stirring ball mill is installed vertically, and the shaft is pivotally supported on the upper end of the stator, and an O-ring and a mechanical seal having a mating ring are provided on the bearing portion for supporting the shaft at the upper end of the stator. When an O-ring is fitted into the bearing and an O-ring is fitted to the annular groove, a tapered shape that expands downward is formed on the lower side of the annular groove. It is preferable to form a notch. That is, a wet stirring ball mill is supported by a cylindrical vertical stator, a slurry supply port provided at the bottom of the stator, a slurry discharge port provided at the upper end of the stator, and an upper end of the stator. A shaft that is rotationally driven by the driving means, a pin, a disk or an annulus type rotor that is fixed to the shaft and that stirs and mixes the dispersion medium filled in the stator and the slurry supplied from the supply port, and near the discharge port Is provided with a separator that separates the dispersion medium from the slurry and a mechanical seal that is provided at the bearing portion that supports the shaft at the upper end of the stator, and an O-ring that contacts the mating ring of the mechanical seal is fitted. A tapered cut is formed in the lower part of the annular groove that expands downward. It is preferable.

According to the above-described wet stirring ball mill, the mechanical seal is provided at the shaft center where the dispersion medium or slurry has little kinetic energy and at the upper end of the stator above the liquid surface level. And dispersion medium and slurry can be greatly reduced between the lower portion of the O-ring fitting groove.
In addition, the lower portion of the annular groove into which the O-ring is fitted is expanded downward by cutting, and the clearance is widened. Therefore, the slurry and the dispersion medium are jammed and solidified due to clogging or solidification. This prevents the mating ring from following the seal ring smoothly and maintains the function of the mechanical seal. In addition, since the lower part of the fitting groove into which the O-ring is fitted has a V-shaped cross section and the whole is not thin, the strength is not impaired, and the holding function of the O-ring is also impaired. Absent.

  In particular, the separator has two disks each provided with a fitting groove for a blade on the opposite inner surface, a blade that is fitted in the fitting groove and is interposed between the disks, and a blade. It is preferable to include a supporting means for sandwiching the disk from both sides. That is, as the wet stirring ball mill, a cylindrical stator, a slurry supply port provided at one end of the stator, a slurry discharge port provided at the other end of the stator, and the stator filled A dispersion medium, a rotor for stirring and mixing the slurry supplied from the supply port, and connected to the discharge port and rotatably provided in the stator, and the dispersion medium and the slurry are rotated by the action of centrifugal force. And an impeller-type separator that discharges the slurry from the discharge port, and two disks each having a blade fitting groove on the inner surface facing the separator, and the fitting The blade interposed between the discs by fitting in a mating groove and the disc with the blades interposed are sandwiched from both sides It is preferred to make a support means. In this case, in a preferred embodiment, the support means is composed of a shaft step that forms a stepped shaft and a cylindrical presser unit that fits into the shaft and presses the disk, and the shaft step and the presser unit are used to hold the blade. The intervening disc is sandwiched and supported from both sides. Such a wet stirring ball mill efficiently separates the dispersion medium and the slurry, improves the productivity of the dispersion, and can produce a large amount of dispersion in a short time. Benefits are gained.

Hereinafter, in order to describe the configuration of the above-described vertical wet stirring ball mill more specifically, an embodiment of the wet ball mill will be described. However, the stirrer used for producing the undercoat layer coating solution of the present invention is not limited to those exemplified here.
FIG. 1 is a longitudinal sectional view schematically showing the configuration of the wet stirring ball mill of this embodiment. In FIG. 1, slurry (not shown) is supplied to a vertical wet stirring ball mill, pulverized by being stirred with the dispersion medium (not shown) in the mill, and then the dispersion medium is separated by a separator 14 and shaft The material is discharged through a discharge passage 19 formed at the center of 15 shafts, followed by a return route (not shown), and circulated and crushed.

  As shown in detail in FIG. 1, the vertical wet stirring ball mill includes a stator 17 having a longitudinally cylindrical shape and a jacket 16 through which cooling water for cooling the mill is passed, and an axis of the stator 17. The shaft 15 is rotatably supported on the upper portion of the stator 17 and has a mechanical seal in the bearing portion and the shaft center of the upper portion having a hollow discharge passage 19 and a diameter at the lower end portion of the shaft 15. Pin or disk-shaped rotor 21 protruding in the direction, a pulley 24 that is fixed to the top of the shaft 15 and transmits a driving force, a rotary joint 25 that is attached to the upper end of the shaft 15, and a stator 17. A separator 14 for separating media that is fixed to the shaft 15 near the upper part of the inner side of the stator 15 and a bottom portion of the stator 17 that is provided opposite to the shaft end of the shaft 15. A slurry supply port 26 and a screen 28 which is attached on a lattice-like screen support 27 installed in a slurry take-out port 29 provided at an eccentric position at the bottom of the stator 17 and separates the dispersion medium. .

  The separator 14 is composed of a pair of disks 31 fixed to the shaft 15 at a predetermined interval and a blade 32 connecting the disks 31 to form an impeller. Centrifugal force is applied to the dispersion medium and the slurry that have entered, and the dispersion medium is blown outward in the radial direction due to the difference in specific gravity, while the slurry is discharged through the discharge passage 19 at the shaft center of the shaft 15. .

The slurry supply port 26 includes an inverted trapezoidal valve body 35 that fits up and down on a valve seat formed at the bottom of the stator 17, and a bottomed cylindrical body 36 that projects downward from the bottom of the stator 17. When the valve body 35 is pushed up by the supply of the slurry, an annular slit (not shown) is formed between the valve seat 35 and the slurry, so that the slurry is supplied into the stator 17.

The valve body 35 at the time of supplying the raw material rises against the pressure in the mill due to the supply pressure of the slurry fed into the cylindrical body 36, and forms a slit between the valve seat 35 and the valve seat.
In order to eliminate clogging at the slit, the valve body 35 can be lifted up and down to the upper limit position in a short cycle to eliminate biting. The valve body 35 may be vibrated at all times or when the slurry contains a large amount of coarse particles. When the slurry supply pressure rises due to clogging, the valve body 35 is interlocked with this. May be performed.

In addition, as a wet stirring ball mill which has a structure as illustrated in this embodiment, specifically, for example, Ultra Apex Mill manufactured by Kotobuki Industries Co., Ltd. can be mentioned.
Since the wet stirring ball mill of the present embodiment is configured as described above, the slurry is dispersed by the following procedure. That is, a dispersion medium (not shown) is filled in the stator 17 of the wet stirring ball mill of this embodiment, and the rotor 21 and the separator 14 are driven to rotate by external power, while a certain amount of slurry is supplied. 26. Thus, the slurry is supplied into the stator 7 through a slit (not shown) formed between the edge of the valve seat and the valve body 35.

  The slurry in the stator 7 and the dispersion medium are agitated and mixed by the rotation of the rotor 21 and the slurry is pulverized. Further, the dispersion medium and the slurry that have entered the separator 14 are separated by the difference in specific gravity due to the rotation of the separator 14, and the dispersion medium having a high specific gravity is blown outward in the radial direction, whereas the slurry having a low specific gravity is transferred to the shaft 15. Is discharged through a discharge passage 19 formed at the axis of the material and returned to the raw material tank. When the pulverization has progressed to some extent, the particle size of the slurry is appropriately measured. When the desired particle size is reached, the raw material pump is stopped, the mill operation is stopped, and the pulverization is terminated.

  In addition, when the metal oxide particles are dispersed using a wet stirring ball mill, there is no limitation on the filling rate of the dispersion medium filled in the wet stirring ball mill, and the metal oxide particles are dispersed until a desired particle size distribution is obtained. If it can be performed, it is arbitrary. However, when the metal oxide particles are dispersed using the vertical wet stirring ball mill as described above, the filling rate of the dispersion medium filled in the wet stirring ball mill is usually 50% or more, preferably 70% or more. , More preferably 80% or more, and usually 100% or less, preferably 95% or less, more preferably 90% or less.

  In the wet stirring ball mill applied to disperse the metal oxide particles, the separator may be a screen or a slit mechanism, but as described above, an impeller type is desirable, and a vertical type is preferable. It is desirable that the wet stirring ball mill be oriented vertically and the separator be provided at the top of the mill. Particularly when the filling rate of the dispersion medium is set within the above range, the grinding is most efficiently performed, and the separator is more than the media filling level. It becomes possible to position it above, and there is an effect that it is possible to prevent the dispersion medium from being discharged on the separator.

  The operating conditions of the wet stirring ball mill applied to disperse the metal oxide particles include the particle size distribution of the metal oxide particles in the coating solution for forming the undercoat layer, and the undercoat layer forming condition. This affects the stability of the coating solution, the surface shape of the undercoat layer formed by coating the coating solution, and the characteristics of the electrophotographic photosensitive member having the undercoat layer formed by coating the coating solution. In particular, the slurry supply speed and the rotational speed of the rotor are considered to have a great influence.

  The slurry supply speed is related to the time during which the slurry stays in the wet stirring ball mill, and is therefore affected by the volume of the mill and its shape. In the case of a commonly used stator, the volume of the wet stirring ball mill is 1 liter (hereinafter referred to as L Is usually 20 kg / hour or more, preferably 30 kg / hour or more, and usually 80 kg / hour or less, preferably 70 kg / hour or less.

Further, the rotational speed of the rotor is affected by parameters such as the rotor shape and the gap with the stator, but in the case of a commonly used stator and rotor, the peripheral speed of the rotor tip is usually 5 m / second or more, preferably The range is 8 m / second or more, more preferably 10 m / second or more, and usually 20 m / second or less, preferably 15 m / second or less, more preferably 12 m / second or less.
Furthermore, there is no limit on the amount of distributed media used. However, the dispersion medium is usually used in a volume ratio of 0.5 to 5 times that of the slurry. In addition to the dispersion medium, a dispersion aid that can be easily removed after dispersion can be used in combination. Examples of the dispersion aid include sodium chloride and sodium nitrate.

The metal oxide particles are preferably dispersed in the presence of a dispersion solvent in a wet manner. Moreover, as long as the metal oxide particles can be appropriately dispersed, components other than the dispersion solvent may coexist. Examples of such components that may coexist include binder resins and various additives.
The dispersion solvent is not particularly limited, but if the solvent used in the coating solution for forming the undercoat layer is used, it is preferable that a step such as solvent exchange is not required after dispersion. Any one of these dispersion solvents may be used alone, or two or more of these dispersion solvents may be used in any combination and ratio, and may be used as a mixed solvent.

From the viewpoint of productivity, the amount of the dispersion solvent used is usually 0.1 parts by weight or more, preferably 1 part by weight or more, and usually 500 parts by weight or less with respect to 1 part by weight of the metal oxide to be dispersed. The range is preferably 100 parts by weight or less.
The temperature at the time of mechanical dispersion can be from the freezing point of the solvent (or mixed solvent) to the boiling point or less, but from the viewpoint of safety during production, it is usually 10 ° C. or more and 200 ° C. or less. It is performed in the range.

After the dispersion treatment using the dispersion medium, it is preferable to separate and remove the dispersion medium from the slurry and to perform ultrasonic treatment. The ultrasonic treatment applies ultrasonic vibration to the metal oxide particles.
There are no particular restrictions on the conditions for ultrasonic treatment such as the vibration frequency, but ultrasonic vibration is applied by an oscillator having a frequency of usually 10 kHz or more, preferably 15 kHz or more, and usually 40 kHz or less, preferably 35 kHz or less.

Moreover, although there is no restriction | limiting in particular in the output of an ultrasonic oscillator, Usually 100W-5kW thing is used.
Furthermore, it is usually better to disperse a small amount of slurry with ultrasonic waves from a small output ultrasonic oscillator than to process a large amount of slurry with ultrasonic waves from a high output ultrasonic oscillator. Therefore, the amount of slurry to be treated at a time is usually 1 L or more, preferably 5 L or more, more preferably 10 L or more, and usually 50 L or less, preferably 30 L or less, more preferably 20 L or less. In this case, the output of the ultrasonic oscillator is usually 200 W or more, preferably 300 W or more, more preferably 500 W or more, and usually 3 kW or less, preferably 2 kW or less, more preferably 1.5 kW or less.

  There is no particular limitation on the method of applying ultrasonic vibration to the metal oxide particles. For example, the method of directly immersing the ultrasonic oscillator in the container containing the slurry, or contacting the ultrasonic oscillator on the outer wall of the container containing the slurry. And a method of immersing a solution containing a slurry in a liquid that has been vibrated by an ultrasonic oscillator. Among these methods, a method of immersing a container containing slurry in a liquid that has been vibrated by an ultrasonic oscillator is preferably used.

In the above case, the liquid to be vibrated by the ultrasonic oscillator is not limited, but examples thereof include water; alcohols such as methanol; aromatic hydrocarbons such as toluene; and fats and oils such as silicone oil. Among them, it is preferable to use water in consideration of safety in production, cost, cleanability and the like.
In the method of immersing a container containing slurry in a liquid that has been vibrated by an ultrasonic oscillator, it is preferable to keep the temperature of the liquid constant because the efficiency of ultrasonic treatment changes depending on the temperature of the liquid. . The temperature of the liquid to which vibration is applied may increase due to the applied ultrasonic vibration. The temperature of the liquid is usually 5 ° C. or higher, preferably 10 ° C. or higher, more preferably 15 ° C. or higher, and usually 60 ° C. or lower, preferably 50 ° C. or lower, more preferably 40 ° C. or lower. It is preferable to do.

  There is no limitation on the container in which the slurry is placed when ultrasonic treatment is performed. For example, any container can be used as long as it is a container that is normally used to contain a coating solution for forming an undercoat layer used for forming a photosensitive layer for an electrophotographic photoreceptor. Specific examples include a resin container such as polyethylene and polypropylene, a glass container, and a metal can. Among these, metal cans are preferable, and in particular, 18 liter metal cans as defined in JIS Z 1602 are preferably used. This is because it is hardly affected by organic solvents and is strong against impact.

  Moreover, the slurry after dispersion and the slurry after ultrasonic treatment are used after being filtered as necessary in order to remove coarse particles. As filtration media in this case, any filtration media such as cellulose fiber, resin fiber, and glass fiber, which are usually used for filtration, may be used. As a form of the filtration media, a so-called wind filter in which various fibers are wound around a core material is preferable because of a large filtration area and high efficiency. As the core material, any conventionally known core material can be used. Examples of the core material include stainless steel core materials and polypropylene-made resin core materials that do not dissolve in the slurry and the solvent contained in the slurry.

The slurry thus obtained further contains a solvent, a binder resin (binder), other components (auxiliaries, etc.) as necessary to form a coating liquid for forming an undercoat layer. In addition, the metal oxide particles are used as needed for the solvent and binder resin for the coating liquid for forming the undercoat layer, as needed, before, during and after the dispersion or ultrasonic treatment step. What is necessary is just to mix with the other component made. Therefore, the mixing of the metal oxide particles with the solvent, the binder resin, and other components does not necessarily have to be performed after the dispersion or ultrasonic treatment.
According to the method for producing a coating liquid for forming the undercoat layer, it is possible to produce the coating liquid efficiently and obtain a coating liquid with higher storage stability. Therefore, a higher quality electrophotographic photosensitive member can be obtained efficiently.

<Coating formation method of undercoat layer>
The undercoat layer for the electrophotographic photosensitive member according to the present invention can be formed by applying a coating solution for forming the undercoat layer according to the present invention on the conductive support and drying it. Although there is no restriction | limiting in the method of apply | coating the coating liquid for forming the undercoat layer based on this invention, For example, dip coating, spray coating, nozzle coating, spiral coating, ring coating, bar coating coating, roll coating coating, a blade Application etc. are mentioned. In addition, these coating methods may be implemented only by 1 type, and may be implemented in arbitrary combinations of 2 or more types.

  Examples of the spray coating method include air spray, airless spray, electrostatic air spray, electrostatic airless spray, rotary atomizing electrostatic spray, hot spray, and hot airless spray. Further, considering the atomization degree for obtaining a uniform film thickness, the adhesion efficiency, etc., in the rotary atomizing electrostatic spray, the conveying method disclosed in the republished publication No. 1-805198, that is, cylindrical It is preferable that the workpiece is continuously conveyed without being spaced apart in the axial direction while rotating the workpiece. Thereby, an electrophotographic photoreceptor excellent in uniformity of the thickness of the undercoat layer can be obtained with a comprehensively high adhesion efficiency.

Examples of the spiral coating method include a method using a liquid injection coating machine or a curtain coating machine disclosed in Japanese Patent Laid-Open No. 52-119651, and paint from a minute opening disclosed in Japanese Patent Laid-Open No. 1-2231966. There are a method of continuously flying in a streak shape, a method using a multi-nozzle body disclosed in JP-A-3-193161, and the like.
In the case of the dip coating method, the total solid concentration of the coating solution for forming the undercoat layer is usually 1% by weight or more, preferably 10% by weight or more, and usually 50% by weight or less, preferably 35% by weight or less. The viscosity is preferably 0.1 cps or more, and preferably 100 cps or less. Note that 1 cps = 1 × 10 ⁻³ Pa · s.

After coating, the coating film is dried, but it is preferable to adjust the drying temperature and time so that necessary and sufficient drying is performed. Usually, the undercoat layer is dried by air drying at room temperature and normal pressure, but may be dried by heating. The drying temperature at the time of heat drying is usually 100 ° C or higher, preferably 110 ° C or higher, more preferably 115 ° C or higher, and usually 250 ° C or lower, preferably 170 ° C or lower, more preferably 140 ° C or lower. is there. There is no restriction | limiting in the drying method, For example, a hot air dryer, a steam dryer, an infrared dryer, a far-infrared dryer, etc. can be used.
<Advantages of the coating liquid for forming the undercoat layer of the present invention>
The coating liquid for forming the undercoat layer of the present invention has high storage stability. There are various storage stability indexes. For example, the coating liquid for forming the undercoat layer of the present invention has a viscosity change rate at the time of preparation and after storage at room temperature for 120 days (that is, after storage for 120 days). The value obtained by dividing the difference in viscosity between the viscosity and the viscosity during production by the viscosity during production is usually 20% or less, preferably 15% or less, and more preferably 10% or less. The viscosity can be measured by a method according to JIS Z 8803 using an E-type viscometer (manufactured by Tokimec, product name ED).
In addition, if a coating solution for forming the undercoat layer of the present invention is used, it is possible to produce an electrophotographic photoreceptor with high quality and high efficiency.

<Toner>
The toner that is a developer for developing the latent image according to the present invention is a toner having a specific circularity. By using the toner having a specific circularity as described above, the image forming apparatus of the present invention can form a high-quality image.
<Toner circularity>
The shape of the toner of the present invention is such that the shape of each particle included in the particle group constituting the toner is closer to each other, and the closer to a sphere, the less likely the localization of the charge amount in the toner particles occurs. Although the developability tends to be uniform, which is preferable for improving the image quality, if the toner shape is too close to a perfect sphere, the toner remains on the surface of the electrophotographic photosensitive member due to poor cleaning of the toner after image formation. In such a case, it is necessary to perform strong cleaning so as not to cause defective cleaning, and as a result, the electrophotographic photosensitive member is likely to be worn due to strong cleaning. Or the surface of the electrophotographic photosensitive member may be shortened. In addition, it is difficult to produce a perfect spherical toner, and the cost of the toner increases, so that the industrial utility value is low.

Therefore, specifically, the average circularity measured by the flow type particle image analyzer is usually 0.940 or more, preferably 0.950 or more, more preferably 0.960 or more. The upper limit of the average circularity is not limited as long as it is 1.000 or less, but is preferably 0.995 or less, more preferably 0.990 or less.
The average circularity is used as a simple method for quantitatively expressing the shape of toner particles. In the present invention, the average circularity is measured using a flow type particle image analyzer FPIA-2000 manufactured by Sysmex Corporation. Then, the circularity [a] of the measured particle is obtained by the following equation (A).

Circularity a = L ₀ / L (A)
(In Formula (A), L ₀ represents the perimeter of a circle having the same projected area as the particle image, and L represents the perimeter of the particle image when image processing is performed.)
The circularity is an index of the degree of unevenness of the toner particles, and indicates 1.00 when the toner is a perfect sphere. The more complicated the surface shape, the smaller the circularity.

  A specific method for measuring the average circularity is as follows. That is, a surfactant (preferably alkylbenzene sulfonate) is added as a dispersant to 20 ml of water from which impurities in the container have been removed in advance, and about 0.05 g of a measurement sample (toner) is further added. The suspension in which this sample is dispersed is irradiated with ultrasonic waves for 30 seconds, and the dispersion concentration is set to 3.0 to 8.0 thousand pieces / μL (microliter). The circularity distribution of particles having an equivalent circle diameter of 60 μm or more and less than 160 μm is measured.

<Toner type>
The toner of the present invention is not limited as long as it has the above average circularity. Various types of toner are usually obtained depending on the production method, and any of the toners of the present invention can be used.
Hereinafter, the toner manufacturing method and the type of toner will be described.
The toner of the present invention may be produced by any conventionally known method, for example, a toner produced by a polymerization method or a melt suspension method, and further, a so-called pulverized toner is treated with heat or the like. Although a spheroidized toner can be used, a toner produced by a so-called polymerization method that generates toner particles in an aqueous medium is preferable.

Examples of the polymerization toner include suspension polymerization toner and emulsion polymerization aggregation toner. In particular, the emulsion polymerization aggregation method is a method for producing toner by aggregating polymer resin fine particles and a colorant in a liquid medium, and adjusting the particle size and circularity of the toner by controlling the aggregation conditions. Is preferable.
In order to improve the releasability, low-temperature fixing property, high-temperature offset property, filming resistance and the like of the toner, a method of incorporating a low softening point substance (so-called wax) into the toner has been proposed. In the melt-kneading pulverization method, it is difficult to increase the amount of wax contained in the toner, and the limit is about 5% by weight with respect to the polymer (binder resin). In contrast, the polymerized toner can contain a low softening point substance in a large amount (5 to 30% by weight). The polymer here is one of the materials constituting the toner. For example, in the case of a toner manufactured by an emulsion polymerization aggregation method described later, the polymer is obtained by polymerizing a polymerizable monomer.
Hereinafter, the toner produced by the emulsion polymerization aggregation method will be described in more detail.
When a toner is produced by an emulsion polymerization aggregation method, the production process usually includes a polymerization process, a mixing process, an aggregation process, a fusion process, and a washing / drying process. That is, generally, polymer primary particles are obtained by emulsion polymerization (polymerization step), and if necessary, a colorant (pigment), wax, charge control agent, etc. are dispersed in a dispersion containing the polymer primary particles. The mixture is mixed (mixing step), and a flocculant is added to the dispersion to agglomerate primary particles to form particle agglomerates (aggregation step). Thus, particles are obtained (fusion process), and the obtained particles are washed and dried (washing / drying process) to obtain mother particles.

<Polymerization process>
The polymer fine particles (polymer primary particles) are not particularly limited. Therefore, either a fine particle obtained by polymerizing a polymerizable monomer in a liquid medium by a suspension polymerization method, an emulsion polymerization method or the like, or a fine particle obtained by pulverizing a lump of a polymer such as a resin is a polymer. It may be used as primary particles. However, a polymerization method, particularly an emulsion polymerization method, in particular, a method using wax as a seed in emulsion polymerization is preferable. When wax is used as a seed in emulsion polymerization, fine particles having a structure in which the polymer wraps the wax can be produced as polymer primary particles. According to this method, the wax can be contained in the toner without being exposed on the surface of the toner. For this reason, there is no contamination of the apparatus member by the wax, the chargeability of the toner is not impaired, and the low temperature fixing property, high temperature offset property, filming resistance, releasability, etc. of the toner can be improved. it can.

Hereinafter, a description will be given of a method of performing emulsion polymerization using wax as a seed, thereby obtaining polymer primary particles.
The emulsion polymerization method may be performed according to a conventionally known method. Usually, a wax is dispersed in a liquid medium in the presence of an emulsifier to form wax fine particles, and a polymerization initiator, a polymerizable monomer that gives a polymer by polymerization, that is, a polymerizable carbon-carbon double bond. Polymerization is carried out by mixing and stirring the compound having, and if necessary, a chain transfer agent, a pH adjuster, a polymerization degree adjuster, an antifoaming agent, a protective colloid, an internal additive and the like. As a result, an emulsion is obtained in which polymer fine particles (that is, polymer primary particles) having a structure in which the polymer wraps the wax are dispersed in the liquid medium. Examples of the structure in which the polymer wraps the wax include a core-shell type, a phase separation type, and an occlusion type, and the core-shell type is preferable.
(I. Wax)
As the wax, any known wax that can be used for this purpose can be used. For example, olefin waxes such as low molecular weight polyethylene, low molecular weight polypropylene and copolymer polyethylene; paraffin wax; silicone wax having an alkyl group; fluororesin wax such as low molecular weight polytetrafluoroethylene; higher fatty acids such as stearic acid; eicosanol Long-chain aliphatic alcohols such as behenate behenate, montanic acid ester, stearic acid ester ester wax having a long-chain aliphatic group; distearyl ketone and other long-chain alkyl group ketones; hydrogenated castor oil, Plant waxes such as carnauba wax; esters or partial esters obtained from polyhydric alcohols such as glycerin and pentaerythritol and long chain fatty acids; higher fatty acid amides such as oleic acid amide and stearic acid amide; Ester and the like. Especially, what has at least 1 the endothermic peak by a differential thermal analysis (DSC) in 50-100 degreeC is preferable.

Among the waxes, for example, ester waxes, paraffin waxes, olefin waxes such as low molecular weight polypropylene and copolymer polyethylene, silicone waxes, and the like are preferable because a release effect can be obtained in a small amount. Paraffin wax is particularly preferable.
In addition, 1 type may be used for wax and it may use 2 or more types together by arbitrary combinations and a ratio.
When using wax, the amount used is arbitrary. However, it is desirable that the wax is usually 3 parts by weight or more, preferably 5 parts by weight or more, and usually 40 parts by weight or less, preferably 30 parts by weight or less based on 100 parts by weight of the polymer. If the amount of wax is too small, the fixing temperature range may be insufficient. If the amount is too large, the apparatus members may be contaminated and the image quality may be deteriorated.

(Ii. Emulsifier)
There is no restriction | limiting in an emulsifier, Arbitrary things can be used in the range which does not impair the effect of this invention remarkably. For example, any of nonionic, anionic, cationic and amphoteric surfactants can be used.

Examples of the nonionic surfactant include polyoxyalkylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyalkylene alkyl phenyl ethers such as polyoxyethylene octylphenyl ether, and sorbitan fatty acid esters such as sorbitan monolaurate. And the like.
Examples of the anionic surfactant include fatty acid salts such as sodium stearate and sodium oleate, alkylaryl sulfonates such as sodium dodecylbenzene sulfonate, and alkyl sulfate salts such as sodium lauryl sulfate. .

Furthermore, examples of the cationic surfactant include alkylamine salts such as laurylamine acetate and quaternary ammonium salts such as lauryltrimethylammonium chloride.
Examples of amphoteric surfactants include alkylbetaines such as lauryl betaine.
Among these, nonionic surfactants and anionic surfactants are preferable.
In addition, 1 type may be used for an emulsifier and it may use 2 or more types together by arbitrary combinations and a ratio.
Furthermore, the amount of the emulsifier is arbitrary as long as the effects of the present invention are not significantly impaired, but the emulsifier is usually used at a ratio of 1 to 10 parts by weight with respect to 100 parts by weight of the polymerizable monomer.

(Iii. Liquid medium)
As the liquid medium, an aqueous medium is usually used, and water is particularly preferably used. However, the quality of the liquid medium is also related to the coarsening due to reaggregation of particles in the liquid medium. When the conductivity of the liquid medium is high, the dispersion stability with time tends to deteriorate. Therefore, when an aqueous medium such as water is used as the liquid medium, it is preferable to use ion-exchanged water or distilled water that has been desalted so that the electrical conductivity is usually 10 μS / cm or less, preferably 5 μS / cm or less. preferable. The conductivity is measured at 25 ° C. using a conductivity meter (personal SC meter model SC72 and detector SC72SN-11 manufactured by Yokogawa Electric Corporation).
Moreover, although there is no restriction | limiting in the usage-amount of a liquid medium, The quantity of about 1-20 weight times is normally used with respect to a polymerizable monomer.
By dispersing the wax in the liquid medium in the presence of an emulsifier, fine wax particles are obtained. The order of blending the emulsifier and the wax in the liquid medium is arbitrary, but usually the emulsifier is first blended in the liquid medium and then the wax is mixed. Moreover, you may mix | blend an emulsifier with a liquid medium continuously.

(Iv. Polymerization initiator)
After preparing the wax fine particles, a polymerization initiator is blended in the liquid medium. Any polymerization initiator can be used as long as the effects of the present invention are not significantly impaired. For example, persulfates such as sodium persulfate and ammonium persulfate; organic peroxides such as t-butyl hydroperoxide, cumene hydroperoxide and p-menthane hydroperoxide; inorganics such as hydrogen peroxide Examples include peroxides. Of these, inorganic peroxides are preferable. In addition, 1 type may be used for a polymerization initiator and it may use 2 or more types together by arbitrary combinations and a ratio.

In addition, other examples of the polymerization initiator include persulfates, organic or inorganic peroxides, and reducing organic compounds such as ascorbic acid, tartaric acid, citric acid, sodium thiosulfate, sodium bisulfite, metabisulfate. A redox initiator can also be used in combination with reducing inorganic compounds such as sodium sulfite. In this case, reducing inorganic compounds may be used alone or in combination of two or more in any combination and ratio.
Moreover, there is no restriction | limiting in the usage-amount of a polymerization initiator, It is arbitrary. However, the polymerization initiator is usually used at a ratio of 0.05 to 2 parts by weight with respect to 100 parts by weight of the polymerizable monomer.

(V. Polymerizable monomer)
After the wax fine particles are prepared, a polymerizable monomer is blended in the liquid medium in addition to the polymerization initiator. There is no particular limitation on the polymerizable monomer, but for example, styrenes, (meth) acrylic acid esters, acrylamides, monomers having Bronsted acidic groups (hereinafter simply referred to as “acidic monomers”) ), A monofunctional monomer such as a monomer having a Bronsted basic group (hereinafter sometimes simply referred to as “basic monomer”). Further, a monofunctional monomer can be used in combination with a polyfunctional monomer.

Examples of styrenes include styrene, methyl styrene, chlorostyrene, dichlorostyrene, p-tert-butyl styrene, pn-butyl styrene, pn-nonyl styrene, and the like.
Examples of the (meth) acrylic acid ester include methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, hydroxyethyl acrylate, 2-ethylhexyl acrylate, and methyl methacrylate. , Ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, hydroxyethyl methacrylate, and 2-ethylhexyl methacrylate.

Examples of acrylamides include acrylamide, N-propyl acrylamide, N, N-dimethyl acrylamide, N, N-dipropyl acrylamide, N, N-dibutyl acrylamide, and the like.
Furthermore, examples of the acidic monomer include monomers having a carboxyl group such as acrylic acid, methacrylic acid, maleic acid, fumaric acid and cinnamic acid; monomers having a sulfonic acid group such as sulfonated styrene; vinylbenzenesulfonamide and the like. And monomers having a sulfonamide group.

Examples of the basic monomer include aromatic vinyl compounds having an amino group such as aminostyrene, nitrogen-containing heterocycle-containing monomers such as vinylpyridine and vinylpyrrolidone; amino groups such as dimethylaminoethyl acrylate and diethylaminoethyl methacrylate. Examples include (meth) acrylic acid esters.
In addition, the acidic monomer and the basic monomer may exist as a salt with a counter ion.

  Furthermore, as the polyfunctional monomer, for example, divinylbenzene, hexanediol diacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, neopentyl glycol diacrylate, Examples include diallyl phthalate. It is also possible to use a monomer having a reactive group such as glycidyl methacrylate, N-methylolacrylamide, or acrolein. Among these, radically polymerizable bifunctional monomers, particularly divinylbenzene and hexanediol diacrylate are preferable.

  Among these, the polymerizable monomer is preferably composed of at least styrenes, (meth) acrylic acid esters, and acidic monomers having a carboxyl group. In particular, styrene is preferred as the styrene, butyl acrylate is preferred as the (meth) acrylic acid ester, and acrylic acid is preferred as the acidic monomer having a carboxyl group.

In addition, 1 type may be used for a polymerizable monomer and it may use 2 or more types together by arbitrary combinations and a ratio.
When emulsion polymerization is performed using wax as a seed, it is preferable to use an acidic monomer or a basic monomer and a monomer other than these in combination. This is because the dispersion stability of the polymer primary particles can be improved by using an acidic monomer or a basic monomer in combination.

  At this time, the compounding amount of the acidic monomer or basic monomer is arbitrary, but the amount of the acidic monomer or basic monomer used is usually 0.05 parts by weight or more, preferably 0 with respect to 100 parts by weight of the total polymerizable monomer. It is desirable that the amount be 5 parts by weight or more, more preferably 1 part by weight or more, and usually 10 parts by weight or less, preferably 5 parts by weight or less. If the blending amount of the acidic monomer or basic monomer is less than the above range, the dispersion stability of the polymer primary particles may be deteriorated, and if it exceeds the upper limit, the chargeability of the toner may be adversely affected.

Moreover, when using a polyfunctional monomer together, the compounding quantity is arbitrary, However, The compounding quantity of the polyfunctional monomer with respect to 100 weight part of polymeric monomers is 0.005 weight part or more normally, Preferably it is 0.00. 1 part by weight or more, more preferably 0.3 part by weight or more, and usually 5 parts by weight or less, preferably 3 parts by weight or less, more preferably 1 part by weight or less. By using a polyfunctional monomer, the fixability of the toner can be improved. At this time, if the amount of the polyfunctional monomer is less than the above range, the high temperature offset resistance may be inferior, and if it exceeds the upper limit, the low temperature fixability may be inferior.
The method for blending the polymerizable monomer into the liquid medium is not particularly limited. For example, any of batch addition, continuous addition, and intermittent addition may be used, but it is preferable to blend continuously from the viewpoint of reaction control. Moreover, when using several polymerizable monomer together, each polymerizable monomer may be mix | blended separately, and may be mix | blended after mixing beforehand. Furthermore, you may mix | blend, changing the composition of a monomer mixture.

(Vi. Chain transfer agent, etc.)
After preparing the above wax fine particles, the liquid medium includes, in addition to the polymerization initiator and the polymerizable monomer, a chain transfer agent, a pH adjuster, a polymerization degree adjuster, and an antifoaming agent as necessary. Additives such as protective colloids and internal additives. Any of these additives can be used as long as the effects of the present invention are not significantly impaired. Moreover, these additives may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

Any known chain transfer agent can be used. Specific examples include t-dodecyl mercaptan, 2-mercaptoethanol, diisopropylxanthogen, carbon tetrachloride, trichlorobromomethane and the like. Moreover, a chain transfer agent is normally used in the ratio of 5 weight part or less with respect to 100 weight part of polymerizable monomers.
Further, any known colloid that can be used for this purpose can be used. Specific examples include partially or completely saponified polyvinyl alcohols such as polyvinyl alcohol, cellulose derivatives such as hydroxyethyl cellulose, and the like.
Examples of the internal additive include those for modifying the adhesiveness, cohesiveness, fluidity, chargeability, surface resistance and the like of toners such as silicone oil, silicone varnish, and fluorine oil.

(Vii. Polymer primary particles)
Polymer initiators, polymerizable monomers, and additives as necessary are mixed in a liquid medium containing wax fine particles, stirred, and polymerized to obtain polymer primary particles. The polymer primary particles can be obtained in the form of an emulsion in a liquid medium.

There is no restriction | limiting in the order which mixes a polymerization initiator, a polymerizable monomer, an additive, etc. with a liquid medium. Further, there are no restrictions on the method of mixing and stirring, and the method is arbitrary.
Furthermore, the reaction temperature of the polymerization (emulsion polymerization reaction) is arbitrary as long as the reaction proceeds. However, the polymerization temperature is usually 50 ° C. or higher, preferably 60 ° C. or higher, more preferably 70 ° C. or higher, and usually 120 ° C. or lower, preferably 100 ° C. or lower, more preferably 90 ° C. or lower.

  The volume average particle diameter of the polymer primary particles is not particularly limited, but is usually 0.02 μm or more, preferably 0.05 μm or more, more preferably 0.1 μm or more, and usually 3 μm or less, preferably 2 μm or less, more preferably Is 1 μm or less. If the volume average particle size is too small, it may be difficult to control the aggregation rate. If the volume average particle size is too large, the particle size of the toner obtained by aggregation tends to be large, and the target particles It may be difficult to obtain a toner having a diameter. The volume average particle diameter can be measured with a particle size analyzer using a dynamic light scattering method described later.

  In the present invention, the volume particle size distribution is measured by a dynamic light scattering method. This method obtains the particle size distribution by detecting the speed of Brownian motion of finely dispersed particles, irradiating the particles with laser light, and detecting light scattering (Doppler shift) with different phases according to the speed. It is. In the actual measurement, the above volume particle size is set as follows using an ultrafine particle size distribution measuring apparatus using a dynamic light scattering method (manufactured by Nikkiso Co., Ltd., UPA-EX150, hereinafter abbreviated as UPA-EX). At.

Measurement upper limit: 6.54 μm
Measurement lower limit: 0.0008 μm
Number of channels: 52
Measurement time: 100 sec.
Measurement temperature: 25 ° C
Particle permeability: Absorption Particle refractive index: N / A (not applicable)
Particle shape: non-spherical density: 1 g / cm ³
Dispersion medium type: WATER
Dispersion medium refractive index: 1.333
At the time of measurement, measurement is performed with a sample in which a dispersion of particles is diluted with a liquid medium so that the sample concentration index is in the range of 0.01 to 0.1 and is dispersed with an ultrasonic cleaner. The volume average particle diameter according to the present invention is measured by using the result of the volume particle size distribution as an arithmetic average value.

  The polymer constituting the polymer primary particles has at least one of peak molecular weights in gel permeation chromatography, usually 3000 or more, preferably 10,000 or more, more preferably 30,000 or more, and usually 100,000 or less. , Preferably it is 70,000 or less, more preferably 60,000 or less. When the peak molecular weight is in the above range, the durability, storage stability, and fixability of the toner tend to be good. Here, as the peak molecular weight, a value converted to polystyrene is used, and components insoluble in a solvent are excluded in measurement. The peak molecular weight can be measured in the same manner as the toner described later.

  In particular, when the polymer is a styrene resin, the lower limit of the number average molecular weight of the polymer in gel permeation chromatography is usually 2000 or more, preferably 2500 or more, more preferably 3000 or more, and the upper limit is Usually, it is 50,000 or less, preferably 40,000 or less, more preferably 35,000 or less. Furthermore, the lower limit of the weight average molecular weight of the polymer is usually 20,000 or more, preferably 30,000 or more, more preferably 50,000 or more, and the upper limit is usually 1,000,000 or less, preferably 500,000 or less. This is because when a styrene resin in which at least one of the number average molecular weight and the weight average molecular weight, preferably both falls within the above ranges, is used as the polymer, the obtained toner has good durability, storage stability and fixability. is there. Further, the molecular weight distribution may have two main peaks. The styrene resin refers to a resin in which styrenes occupy usually 50% by weight or more, preferably 65% by weight or more based on the total polymer.

  Further, the softening point of the polymer (hereinafter sometimes abbreviated as “Sp”) is usually 150 ° C. or less, preferably 140 ° C. or less from the viewpoint of low energy fixing, and usually 80 ° C. or more. Preferably it is 100 degreeC or more from the point of high temperature offset resistance and durability. Here, the softening point of the polymer is determined by measuring 1.0 g of a sample with a nozzle 1 mm × 10 mm, a load of 30 kg, a preheating time of 50 ° C. for 5 minutes, and a temperature rising rate of 3 ° C./min in a flow tester. The temperature at the midpoint of the strand from the start to the end of the flow can be obtained.

Furthermore, the glass transition temperature [Tg] of the polymer is usually 80 ° C. or lower, preferably 70 ° C. or lower. If the glass transition temperature [Tg] of the polymer is too high, low energy fixing may not be possible. The lower limit of the glass transition temperature [Tg] of the polymer is usually 40 ° C. or higher, preferably 50 ° C. or higher. If the glass transition temperature [Tg] of the polymer is too low, the blocking resistance may be lowered. Here, the glass transition temperature [Tg] of the polymer is the intersection of the two tangent lines by drawing a tangent line at the start of the transition (inflection) of the curve measured at a heating rate of 10 ° C./min in a differential scanning calorimeter. It can be calculated as the temperature.
The softening point and glass transition temperature [Tg] of the polymer can be adjusted to the above ranges by adjusting the kind of the polymer, the monomer composition ratio, the molecular weight, and the like.

<Mixing process and aggregation process>
By mixing and aggregating pigment particles in the emulsion in which the polymer primary particles are dispersed, an emulsion of aggregates (aggregated particles) containing a polymer and a pigment is obtained. In this case, it is preferable to prepare a pigment particle dispersion in which the pigment is uniformly dispersed in advance in a liquid medium using a surfactant or the like, and mix this with an emulsion of polymer primary particles. At this time, an aqueous solvent such as water is usually used as the liquid medium of the pigment particle dispersion, and the pigment particle dispersion is prepared as an aqueous dispersion. At that time, if necessary, a wax, a charge control agent, a release agent, an internal additive and the like may be mixed into the emulsion. Moreover, in order to maintain the stability of the pigment particle dispersion, the above-described emulsifier may be added.

As the polymer primary particles, the polymer primary particles obtained by emulsion polymerization can be used. At this time, the polymer primary particles may be used alone or in combination of two or more in any combination and ratio. Furthermore, polymer primary particles (hereinafter, referred to as “combined polymer particles” as appropriate) produced with raw materials and reaction conditions different from those of the emulsion polymerization described above may be used in combination.
Examples of the combined polymer particles include fine particles obtained by suspension polymerization or pulverization. Resin can be used as the material for such combined polymer particles. As this resin, for example, vinyl acetate, vinyl chloride, vinyl, in addition to the monomer (co) polymer used for the emulsion polymerization described above. Thermoplastics such as homopolymers or copolymers of vinyl monomers such as alcohol, vinyl butyral, vinyl pyrrolidone, saturated polyester resins, polycarbonate resins, polyamide resins, polyolefin resins, polyarylate resins, polysulfone resins, polyphenylene ether resins Examples thereof include thermosetting resins such as resins and unsaturated polyester resins, phenol resins, epoxy resins, urethane resins, and rosin-modified maleic resins. These combined polymer particles may be used alone or in combination of two or more in any combination and ratio. However, the ratio of the combined polymer particles is usually 5% by weight or less, preferably 4% by weight or less, more preferably 3% by weight or less based on the total of the polymer primary particles and the polymer of the combined polymer particles. .

Moreover, there is no restriction | limiting in a pigment, According to the use, arbitrary things can be used. However, although the pigment is usually present in the form of particles as colorant particles, it is preferable that the pigment particles have a smaller density difference from the polymer primary particles in the emulsion polymerization aggregation method. This is because when the density difference is smaller, a uniform aggregated state is obtained when the polymer temporary particles and the pigment are aggregated, and thus the performance of the obtained toner is improved. The density of the polymer primary particles is usually 1.1 to 1.3 g / cm ³ .

From the above viewpoint, the true density of the pigment particles measured by the pycnometer method defined in JIS K 5101-11-1: 2004 is usually 1.2 g / cm ³ or more, preferably 1.3 g / cm ³ or more. Also, it is usually less than 2.0 g / cm ³ , preferably 1.9 g / cm ³ or less, more preferably 1.8 g / cm ³ or less. When the true density of the pigment is large, the sedimentation property in a liquid medium tends to deteriorate. In addition, considering issues such as storage stability and sublimation, the pigment is preferably carbon black or an organic pigment.

Examples of pigments that satisfy the above conditions include yellow pigments, magenta pigments, and cyan pigments shown below. Further, as the black pigment, carbon black or a mixture of the following yellow pigment / magenta pigment / cyan pigment mixed with black is used.
Among these, carbon black used as a black pigment exists as an aggregate of very fine primary particles, and when dispersed as a pigment particle dispersion, the carbon black particles are likely to become coarse due to reaggregation. . The degree of reagglomeration of carbon black particles is correlated with the amount of impurities contained in carbon black (the degree of residual undecomposed organic matter), and if there are many impurities, coarsening due to reaggregation after dispersion is significant. Show the trend.

For quantitative evaluation of the amount of impurities, the ultraviolet absorbance of the toluene extract of carbon black measured by the following measurement method is usually 0.05 or less, preferably 0.03 or less. Generally, carbon black produced by the channel method tends to have a large amount of impurities, and therefore, carbon black produced by the furnace method is preferred as the toner of the present invention.
The ultraviolet absorbance (λc) of carbon black is determined by the following method. That is, first, 3 g of carbon black was sufficiently dispersed and mixed in 30 ml of toluene. Filter using 5C filter paper. Thereafter, the filtrate was put in a quartz cell having a 1 cm square light absorption part, and the absorbance at a wavelength of 336 nm was measured using a commercially available ultraviolet spectrophotometer (λs), and the absorbance of only toluene as a reference was measured by the same method. From (λo), the ultraviolet absorbance is obtained by λc = λs−λo. Examples of commercially available spectrophotometers include an ultraviolet-visible spectrophotometer (UV-3100PC) manufactured by Shimadzu Corporation.

Moreover, as a yellow pigment, the compound represented by the condensed azo compound, the isoindolinone compound, etc. is used, for example. Specifically, C.I. I. Pigment Yellow 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 109, 110, 111, 128, 129, 147, 168, 180, 185 and the like are preferably used.
Further, examples of magenta pigments include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds. Specifically, C.I. I. Pigment Red 2, 3, 5, 6, 7, 23, 48: 2, 48: 3, 48: 4, 57: 1, 81: 1, 122, 144, 146, 166, 169, 177, 184, 185, 202, 206, 207, 209, 220, 221, 238, 254, C.I. I. Pigment violet 19 or the like is preferably used.

  Among them, C.I. I. Pigment red 122, 202, 207, 209, C.I. I. A quinacridone pigment represented by pigment violet 19 is particularly preferred. This quinacridone pigment is suitable as a magenta pigment because of its clear hue and high light resistance. Among the quinacridone pigments, C.I. I. A compound represented by CI Pigment Red 122 is particularly preferable.

Examples of cyan pigments that can be used include copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, basic dye lake compounds, and the like. Specifically, C.I. I. Pigment Blue 1, 7, 15, 15: 1, 15: 2, 15: 3, 15: 4, 60, 62, 66 and the like can be used particularly preferably.
In addition, 1 type may be used for a pigment and it may use 2 or more types together by arbitrary combinations and a ratio.

  The above-mentioned pigment is dispersed in a liquid medium and mixed with an emulsion containing polymer primary particles after forming a pigment particle dispersion. At this time, the amount of the pigment particles used in the pigment particle dispersion is usually 3 parts by weight or more, preferably 5 parts by weight or more, and usually 50 parts by weight or less, preferably 40 parts by weight with respect to 100 parts by weight of the liquid medium. Or less. If the blending amount of the colorant exceeds the above range, the pigment concentration is high, which is not preferable because the probability of reaggregation of the pigment particles in the dispersion increases. It is not preferable because it is difficult to obtain a distribution.

The ratio of the amount of the pigment used relative to the polymer contained in the polymer primary particles is usually 1% by weight or more, preferably 3% by weight or more, and usually 20% by weight or less, preferably 15% by weight or less. If the amount of the pigment used is too small, the image density may be thinned, and if it is too large, the aggregation control may be difficult.
Further, the pigment particle dispersion may contain a surfactant. Although there is no restriction | limiting in particular in this surfactant, For example, the thing similar to the surfactant illustrated as an emulsifier in description of an emulsion polymerization method is mentioned. Of these, nonionic surfactants, anionic surfactants such as alkylaryl sulfonates such as sodium dodecylbenzenesulfonate, and polymer surfactants are preferably used. Moreover, 1 type of surfactant may be used in this case, and 2 or more types may be used together by arbitrary combinations and a ratio.

In addition, the ratio of the pigment which occupies for a pigment particle dispersion is 10 to 50 weight% normally.
Further, as the liquid medium of the pigment particle dispersion, an aqueous medium is usually used, and preferably water is used. At this time, the water quality of the polymer primary particles and the pigment particle dispersion is also related to the coarsening due to reaggregation of each particle, and if the electrical conductivity is high, the dispersion stability with time tends to deteriorate. Therefore, it is preferable to use ion-exchanged water or distilled water that has been desalted so that the electrical conductivity is usually 10 μS / cm or less, preferably 5 μS / cm or less. The conductivity is measured at 25 ° C. using a conductivity meter (personal SC meter model SC72 and detector SC72SN-11 manufactured by Yokogawa Electric Corporation).

Moreover, when mixing a pigment with the emulsion containing a polymer primary particle, you may mix a wax with an emulsion. As the wax, the same waxes described in the explanation of the emulsion polymerization method can be used. The wax may be mixed before, during or after mixing the pigment with the emulsion containing the polymer primary particles.
Moreover, when mixing a pigment with the emulsion containing a polymer primary particle, you may mix a charge control agent with an emulsion.

  As the charge control agent, any known charge control agent can be used. Examples of the positively chargeable charge control agent include nigrosine dyes, quaternary ammonium salts, triphenylmethane compounds, imidazole compounds, polyamine resins, and the like. Examples of negative charge control agents include azo complex compound dyes containing atoms such as Cr, Co, Al, Fe, and B; metal salts or metal complexes of salicylic acid or alkylsalicylic acid; curixarene compounds, benzyl Examples include metal salts or metal complexes of acids, amide compounds, phenol compounds, naphthol compounds, and phenol amide compounds. Among these, colorless or light-colored ones are preferably selected in order to avoid color tone problems as toners, and quaternary ammonium salts and imidazole compounds are particularly preferable as positively chargeable charge control agents, and negatively chargeable charge control agents. As these, alkyl salicylic acid complex compounds and curixarene compounds containing atoms such as Cr, Co, Al, Fe and B are preferred. In addition, 1 type may be used for a charge control agent and it may use 2 or more types together by arbitrary combinations and a ratio.

Although there is no restriction | limiting in the usage-amount of a charge control agent, Usually 0.01 weight part or more with respect to 100 weight part of polymers, Preferably it is 0.1 weight part or more, Moreover, 10 weight part or less, Preferably it is 5 weight part or less. It is. If the amount of the charge control agent used is too small or too large, the desired charge amount may not be obtained.
The charge control agent may be mixed before, during or after mixing the pigment with the emulsion containing the polymer primary particles.

Moreover, it is desirable that the charge control agent is mixed at the time of aggregation in the state of being emulsified in a liquid medium (usually an aqueous medium) in the same manner as the pigment particles.
After the pigment is mixed in the emulsion containing the polymer primary particles, the polymer primary particles and the pigment are aggregated. As described above, at the time of mixing, the pigment is usually mixed in the state of a pigment particle dispersion.

The aggregation method is not limited and is arbitrary, and examples thereof include heating, electrolyte mixing, pH adjustment, and the like. Especially, the method of mixing electrolyte is preferable.
Examples of the electrolyte in the case of performing aggregation by mixing the electrolyte include chlorides such as NaCl, KCl, LiCl, MgCl ₂ and CaCl ₂ ; Na ₂ SO ₄ , K ₂ SO ₄ , Li ₂ SO ₄ , MgSO ₄ , Examples thereof include inorganic salts such as sulfates such as CaSO ₄ , ZnSO ₄ , Al ₂ (SO ₄ ) ₃ , and Fe ₂ (SO ₄ ) ₃ ; organic salts such as CH ₃ COONa and C ₆ H ₅ SO ₃ Na. Of these, inorganic salts having a divalent or higher polyvalent metal cation are preferred. In addition, 1 type may be used for electrolyte and it may use 2 or more types together by arbitrary combinations and a ratio.

  The amount of electrolyte used varies depending on the type of electrolyte, but is usually 0.05 parts by weight or more, preferably 0.1 parts by weight or more, and usually 25 parts by weight or less, based on 100 parts by weight of the solid component in the emulsion. Preferably it is 15 weight part or less, More preferably, it is 10 weight part or less. When agglomeration is performed by mixing electrolytes, if the amount of electrolyte used is too small, the agglomeration reaction proceeds slowly and fine particles of 1 μm or less remain after the agglomeration reaction, or the average particle size of the obtained agglomerates There is a risk that the particle size will not be reached, and if the amount of electrolyte used is too large, the agglomeration reaction will occur rapidly, making it difficult to control the particle size. May be included.

The obtained agglomerates are preferably subsequently spheroidized by heating in a liquid medium, similarly to the secondary agglomerates (agglomerates that have undergone the melting step) described later. Heating may be performed under the same conditions as in the case of the secondary aggregate (same conditions as described in the description of the fusion process).
On the other hand, when the aggregation is performed by heating, the temperature condition is arbitrary as long as the aggregation proceeds. Specific temperature conditions are usually 15 ° C. or higher, preferably 20 ° C. or higher, and agglomeration is performed under a temperature condition of polymer primary particle polymer glass transition temperature [Tg] or lower, preferably 55 ° C. or lower. . Although the time for agglomeration is arbitrary, it is usually 10 minutes or longer, preferably 60 minutes or longer, and usually 300 minutes or shorter, preferably 180 minutes or shorter.
In addition, stirring is preferably performed when the aggregation is performed. Although the apparatus used for stirring is not specifically limited, What has a double helical blade is preferable.
The obtained agglomerates may proceed directly to the next step of forming a resin coating layer (encapsulation step), or may proceed to the encapsulation step after performing a fusion treatment by heating in a liquid medium. . Desirably, the encapsulation step is performed after the aggregation step, and the fusing step is performed by heating at a temperature equal to or higher than the glass transition temperature [Tg] of the encapsulated resin fine particles. It is preferable because it does not cause deterioration (such as heat deterioration).

<Encapsulation process>
After obtaining the aggregate, it is preferable to form a resin coating layer on the aggregate as necessary. The encapsulation process for forming a resin coating layer on the aggregate is a process for coating the aggregate with a resin by forming a resin coating layer on the surface of the aggregate. Thereby, the manufactured toner is provided with the resin coating layer. In the encapsulation process, the entire toner may not be completely covered, but the pigment makes it possible to obtain a toner that is not substantially exposed on the surface of the toner particles. Although there is no restriction | limiting in the thickness of the resin coating layer in this case, Usually, it is the range of 0.01-0.5 micrometer.

The method for forming the resin coating layer is not particularly limited, and examples thereof include a spray drying method, a mechanical particle composite method, an in-situ polymerization method, and a submerged particle coating method.
As a method for forming the resin coating layer by the spray drying method, for example, an aggregate forming an inner layer and resin fine particles forming a resin coating layer are dispersed in an aqueous medium to prepare a dispersion, A resin coating layer can be formed on the surface of the aggregate by spraying and drying.

  In addition, as a method for forming a resin coating layer by the mechanical particle composite method, for example, an aggregate that forms an inner layer and resin fine particles that form a resin coating layer are dispersed in a gas phase and mechanically formed in a narrow gap. In this method, resin fine particles are formed into a film on the surface of the aggregate by applying a strong force. For example, a device such as a hybridization system (manufactured by Nara Machinery Co., Ltd.) or a mechano-fusion system (manufactured by Hosokawa Micron) can be used.

Further, as the in-situ polymerization method, for example, the aggregate is dispersed in water, the monomer and the polymerization initiator are mixed, adsorbed on the surface of the aggregate, and heated to polymerize the monomer. Thus, a resin coating layer is formed on the surface of the aggregate that is the inner layer.
The submerged particle coating method includes, for example, reacting or bonding an aggregate forming an inner layer and resin fine particles forming an outer layer in an aqueous medium to form a resin coating layer on the surface of the aggregate forming the inner layer. Is a method of forming

  The resin fine particles used for forming the outer layer are particles mainly having a resin component smaller than the aggregate. The resin fine particles are not particularly limited as long as they are particles composed of a polymer. However, from the viewpoint that the thickness of the outer layer can be controlled, it is preferable to use resin fine particles similar to the polymer primary particles, the aggregates, or the fused particles obtained by fusing the aggregates. Resin fine particles similar to these polymer primary particles can be produced in the same manner as the polymer primary particles in the aggregate used for the inner layer.

The amount of resin fine particles used is arbitrary, but it is usually 1% by weight or more, preferably 5% by weight or more, and usually 50% by weight or less, preferably 25% by weight or less based on the toner particles. Is desirable.
Furthermore, in order to effectively fix or fuse the resin fine particles to the aggregate, the resin fine particles usually have a particle size of about 0.04 to 1 μm.

  The glass transition temperature [Tg] of the polymer component (resin component) used in the resin coating layer is usually 60 ° C. or higher, preferably 70 ° C. or higher, and usually 110 ° C. or lower. Further, the glass transition temperature [Tg] of the polymer component used in the resin coating layer is preferably higher by 5 ° C. or higher than the glass transition temperature [Tg] of the polymer primary particles, and is higher by 10 ° C. or higher. It is more preferable. If the glass transition temperature [Tg] is too low, storage in a general environment is difficult, and if it is too high, sufficient meltability cannot be obtained.

Furthermore, it is preferable to contain polysiloxane wax in the resin coating layer. Thereby, the advantage of improvement in high temperature offset resistance can be obtained. Examples of the polysiloxane wax include silicone wax having an alkyl group.
The content of the polysiloxane wax is not limited, but is usually 0.01% by weight or more, preferably 0.05% by weight or more, more preferably 0.08% by weight or more, and usually 2% by weight or less in the toner. Preferably it is 1 weight% or less, More preferably, you may be 0.5 weight% or less. If the amount of the polysiloxane wax in the resin coating layer is too small, the high temperature offset resistance may be insufficient, and if it is too large, the blocking resistance may decrease.
The method for containing the polysiloxane wax in the resin coating phase is arbitrary. For example, emulsion polymerization is performed using the polysiloxane wax as a seed, and the obtained resin fine particles and the aggregates forming the inner layer are mixed in an aqueous medium. And a resin coating layer containing a polysiloxane wax on the surface of the aggregate forming the inner layer.

<Fusion process>
In the fusing step, the aggregates are melt-integrated by heat-treating the aggregates.
In addition, when encapsulating resin fine particles are formed by forming a resin coating layer on the aggregate, the polymer constituting the aggregate and the resin coating layer on the surface thereof are integrated by heat treatment. It will be. Thereby, the pigment particles are obtained in a form that is not substantially exposed on the surface.
The temperature of the heat treatment in the fusion step is set to a temperature equal to or higher than the glass transition temperature [Tg] of the polymer primary particles constituting the aggregate. Moreover, when a resin coating layer is formed, it is set as the temperature more than the glass transition temperature [Tg] of the polymer component which forms a resin coating layer. Although specific temperature conditions are arbitrary, it is preferable that it is normally 5 (degreeC) or more higher than the glass transition temperature [Tg] of the polymer component which forms a resin coating layer. Although there is no restriction | limiting in the upper limit, below "the temperature 50 (degreeC) higher than the glass transition temperature [Tg] of the polymer component which forms a resin coating layer" is preferable.
The heat treatment time is usually 0.5 to 6 hours, although it depends on the treatment capacity and the production amount.

<Washing and drying process>
When the above-described steps are performed in a liquid medium, after the fusing step, the encapsulated resin particles obtained are washed and dried to remove the liquid medium, thereby obtaining a toner. There are no restrictions on the washing and drying methods, and they are arbitrary.
<Physical properties relating to toner particle size>
There is no restriction on the volume average particle size [Dv] of the toner of the present invention, and it is optional as long as the effect of the present invention is not significantly impaired, but it is usually 4 μm or more, preferably 5 μm or more, and usually 10 μm or less, preferably 8 μm or less. It is. If the volume average particle diameter [Dv] of the toner is too small, the stability of the image quality may be lowered, and if it is too large, the resolution may be lowered.

  In the toner of the present invention, the value [Dv / Dn] obtained by dividing the volume average particle diameter [Dv] by the number average particle diameter [Dn] is usually 1.0 or more, and usually 1.25 or less, preferably It is desirable that it is 1.20 or less, more preferably 1.15 or less. The value of [Dv / Dn] represents the state of the particle size distribution, and the closer this value is to 1.0, the sharper the particle size distribution. A sharper particle size distribution is desirable because the chargeability of the toner becomes uniform.

Further, the toner of the present invention has a volume fraction of a particle size of 25 μm or more, usually 1% or less, preferably 0.5% or less, more preferably 0.1% or less, and further preferably 0.05% or less. . The smaller this value, the better. This means that the ratio of the coarse powder contained in the toner is small. If the coarse powder is small, the amount of toner consumed during the continuous development is small and the image quality is stable, which is preferable. Although it is most preferable that there is no coarse powder having a particle size of 25 μm or more, it is difficult in actual production, and usually it may not be 0.005% or less.
In the toner of the present invention, the volume fraction having a particle size of 15 μm or more is usually 2% or less, preferably 1% or less, more preferably 0.1% or less. Although it is most preferable that there is no coarse powder having a particle size of 15 μm or more, it is difficult in actual production, and it is usually not necessary to make it 0.01% or less.
Further, in the toner of the present invention, it is desirable that the number fraction having a particle size of 5 μm or less is usually 15% or less, preferably 10% or less, since this is effective in improving image fog.

  Here, the volume average particle diameter [Dv], the number average particle diameter [Dn], the volume fraction, the number fraction, and the like of the toner can be measured as follows. In other words, a Coulter Counter Multisizer II or III (manufactured by Beckman Coulter, Inc.) is used as a toner particle size measuring device, and an interface for outputting the number distribution and volume distribution and a general personal computer are connected. To use. In addition, Isoton II is used as the electrolytic solution. As a measuring method, 0.1 to 5 ml of a surfactant (preferably alkylbenzene sulfonate) is added as a dispersant to 100 to 150 ml of the electrolytic solution, and 2 to 20 mg of a measurement sample (toner) is further added. Then, the electrolytic solution in which the sample is suspended is subjected to dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and measured with a 100 μm aperture by the multisizer type II or type III of the Coulter counter. Thus, the number and volume of the toner are measured to calculate the number distribution and the volume distribution, respectively, and the volume average particle diameter [Dv] and the number average particle diameter [Dn] are obtained, respectively.

<Physical properties related to the molecular weight of the toner>
At least one of the peak molecular weights in the gel permeation chromatography (hereinafter sometimes abbreviated as GPC) of the THF soluble content of the toner of the present invention is usually 10,000 or more, preferably 20,000 or more, more preferably 3 It is 10,000 or more, and is usually 150,000 or less, preferably 100,000 or less, more preferably 70,000 or less. THF refers to tetrahydrofuran. When the peak molecular weight is lower than the above range, the mechanical durability in the non-magnetic one-component development method may be deteriorated. When the peak molecular weight is higher than the above range, the low temperature fixability and the fixing strength are deteriorated. There is a case.

Further, the THF-insoluble content of the toner is usually 10% or more, preferably 20% or more, and usually 60% or less, preferably 50% or less, as measured by a weight method by Celite filtration described later. If it is not within the above range, it may be difficult to achieve both mechanical durability and low-temperature fixability.
The peak molecular weight of the toner of the present invention is measured under the following conditions using a measuring apparatus: HLC-8120GPC (manufactured by Tosoh Corporation).

That is, the column is stabilized in a heat chamber at 40 ° C., and tetrahydrofuran (THF) as a solvent is allowed to flow through the column at this temperature at a flow rate of 1 mL (milliliter) per minute. Next, the toner is dissolved in THF and filtered through a 0.2 μm filter, and the filtrate is used as a sample.
The measurement is performed by injecting 50 to 200 μl of a THF solution of a resin with the sample concentration (resin concentration) adjusted to 0.05 to 0.6 mass% into the measuring device. In measuring the molecular weight of the sample (resin component in the toner), the molecular weight distribution of the sample is calculated from the relationship between the logarithmic value of the calibration curve created by several monodisperse polystyrene standard samples and the number of counts. As a standard polystyrene sample for preparing a calibration curve, for example, Pressure Chemical Co. Manufactured by Toyo Soda Kogyo Co., Ltd. and having molecular weights of 6 × 10 ² , 2.1 × 10 ³ , 4 × 10 ³ , 1.75 × 10 ⁴ , 5.1 × 10 ⁴ , 1.1 × 10 ⁵ , It is appropriate to use 3.9 × 10 ⁵ , 8.6 × 10 ⁵ , 2 × 10 ⁶ , 4.48 × 10 ⁶ , and use at least about 10 standard polystyrene samples. An RI (refractive index) detector is used as the detector.

Furthermore, as a column used in the measurement method, in order to accurately measure a molecular weight region of 10 ³ to 2 × 10 ⁶ , it is preferable to combine a plurality of commercially available polystyrene gel columns, for example, manufactured by Waters A combination of μ-styrel 500, 103, 104, 105 and a combination of shodex KA801, 802, 803, 804, 805, 806, 807 manufactured by Showa Denko KK are preferable.
Further, the measurement of the insoluble content of tetrahydrofuran (THF) in the toner can be performed as follows. That is, 1 g of a sample (toner) was added to 100 g of THF, and allowed to stand still at 25 ° C. for 24 hours, and filtered using 10 g of celite. The solvent of the filtrate was distilled off, and the THF soluble content was quantified. Insoluble matter can be calculated.

<Softening point and glass transition temperature of toner>
There is no limitation on the softening point [Sp] of the toner of the present invention, and it is optional as long as the effects of the present invention are not significantly impaired. From the viewpoint of high temperature offset resistance and durability, the softening point is usually 80 ° C. or higher, preferably 100 ° C. or higher.

The toner softening point [Sp] was measured with a flow tester under the conditions of 1.0 g of a sample of 1 mm × 10 mm nozzle, a load of 30 kg, a preheating time of 50 ° C. for 5 minutes, and a heating rate of 3 ° C./min. The temperature at the midpoint of the strand from the start to the end of the flow can be determined.
Further, the glass transition temperature [Tg] of the toner of the present invention is not limited, and may be arbitrary as long as the effects of the present invention are not significantly impaired. Usually, the fixing temperature is 80 ° C. or lower, preferably 70 ° C. or lower. It is desirable because it is possible. The glass transition temperature [Tg] is usually 40 ° C. or higher, preferably 50 ° C. or higher, from the viewpoint of blocking resistance.

The glass transition temperature [Tg] of the toner is obtained by drawing a tangent line at the start of the transition (inflection) of the curve measured with a differential scanning calorimeter at a temperature rising rate of 10 ° C./min. It can be determined as temperature.
The softening point [Sp] and glass transition temperature [Tg] of the toner are greatly affected by the type and composition ratio of the polymer contained in the toner. Therefore, the softening point [Sp] and the glass transition temperature [Tg] of the toner can be adjusted by appropriately optimizing the kind and composition of the polymer. It can also be adjusted by the molecular weight of the polymer, the gel content, the kind of low melting point components such as wax, and the blending amount.

<Wax in toner>
When the toner of the present invention contains a wax, the dispersed particle diameter of the wax in the toner particles is usually 0.1 μm or more, preferably 0.3 μm or more as an average particle diameter, and the upper limit is usually 3 μm or less. Preferably it is 1 micrometer or less. If the dispersed particle size is too small, there is a possibility that the effect of improving the filming resistance of the toner may not be obtained. There is a risk of doing.
The dispersed particle diameter of the wax may be determined by observing an electron microscope after slicing the toner, or wax particles remaining on the filter after elution of the toner polymer with an organic solvent or the like in which the wax does not dissolve. Can be confirmed by a method of measuring with a microscope.
Further, the proportion of the wax in the toner is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.05% by weight or more, preferably 0.1% by weight or more and usually 20% by weight or less, preferably Is 15% by weight or less. If the amount of wax is too small, the fixing temperature range may be insufficient. If the amount is too large, the apparatus members may be contaminated and the image quality may be deteriorated.

<Externally added fine particles>
In order to improve toner fluidity, charging stability, anti-blocking property at high temperatures, and the like, external additive fine particles may be added to the surface of the toner particles.
As a method for attaching the externally added fine particles to the toner particle surface, for example, in the above-described toner manufacturing method, the secondary aggregate and the externally added fine particles are mixed in a liquid medium and then heated to externally add the toner particles onto the toner particles. Examples include a method of fixing fine particles; a method of mixing or fixing externally added fine particles to toner particles obtained by separating, washing, and drying secondary aggregates from a liquid medium.
Examples of the mixer used when the toner particles and the externally added fine particles are mixed in a dry process include a Henschel mixer, a super mixer, a nauter mixer, a V-type mixer, a Redige mixer, a double cone mixer, and a drum type mixer. Can be mentioned. In particular, it is preferable to use a high-speed agitation type mixer such as a Henschel mixer or a super mixer, and appropriately mix the mixture by stirring and mixing uniformly by appropriately setting the blade shape, the number of revolutions, the time, the number of times of driving and stopping, and the like.

In addition, as a device used for fixing toner particles and externally added fine particles in a dry method, a compression shearing device that can apply compressive shear stress, a particle surface melting device that can melt the particle surface, etc. Is mentioned.
A compression shearing apparatus generally has a narrow gap portion composed of a head surface and a head surface, a head surface and a wall surface, or a wall surface and a wall surface that move relatively while maintaining a gap, and particles to be processed are disposed in the gap. By being forced to pass through the portion, compressive stress and shear stress are applied to the particle surface without substantial pulverization. An example of such a compression shearing apparatus is a mechanofusion apparatus manufactured by Hosokawa Micron.

On the other hand, the particle surface melting apparatus is generally configured so as to fix the externally added fine particles by instantaneously heating the mixture of the basic fine particles and the externally added fine particles above the melting start temperature of the basic fine particles using a hot air stream or the like. The Examples of such a particle surface melting apparatus include a surfing system manufactured by Nippon Pneumatic Co., Ltd.
As the externally added fine particles, known fine particles that can be used for this purpose can be used. Examples thereof include inorganic fine particles and organic fine particles.

  Examples of the inorganic fine particles include silicon carbide, boron carbide, titanium carbide, zirconium carbide, hafnium carbide, vanadium carbide, tantalum carbide, niobium carbide, tungsten carbide, chromium carbide, molybdenum carbide, calcium carbide and the like, boron nitride, nitriding Nitride such as titanium, zirconium nitride, silicon nitride, borides such as zirconium boride, silica, colloidal silica, titanium oxide, aluminum oxide, calcium oxide, magnesium oxide, zinc oxide, copper oxide, zirconium oxide, cerium oxide, talc , Oxides and hydroxides such as hydrotalcite, various titanate compounds such as calcium titanate, magnesium titanate, strontium titanate, barium titanate, tricalcium phosphate, calcium dihydrogen phosphate, monohydrogen phosphate calcium Substitution in which part of phosphate ion is replaced by anion Phosphate compound such as calcium phosphate, sulfide such as molybdenum disulfide, fluoride such as magnesium fluoride and fluorocarbon, aluminum stearate, calcium stearate, stearic acid Various carbon blacks including metal soaps such as zinc and magnesium stearate, talc, bentonite, and conductive carbon black can be used. Furthermore, magnetic substances such as magnetite, maghematite, and an intermediate between magnetite and maghematite may be used.

On the other hand, as the organic fine particles, for example, styrene resin, acrylic resin such as polymethyl acrylate and polymethyl methacrylate, epoxy resin, melamine resin, tetrafluoroethylene resin, trifluoroethylene resin, polyvinyl chloride, Fine particles such as polyethylene and polyacrylonitrile can be used.
Among these externally added fine particles, silica, titanium oxide, alumina, zinc oxide, carbon black and the like are particularly preferably used.

In addition, 1 type may be used for an external addition fine particle, and 2 or more types may be used together by arbitrary combinations and a ratio.
In addition, the surface of these inorganic or organic fine particles may be a silane coupling agent, titanate coupling agent, silicone oil, modified silicone oil, silicone varnish, fluorine silane coupling agent, fluorine silicone oil, amino group or fourth group. Surface treatment such as hydrophobization may be performed by a treatment agent such as a coupling agent having a secondary ammonium base. In addition, 1 type may be used for a processing agent and it may use 2 or more types together by arbitrary combinations and a ratio.

Further, the number average particle diameter of the externally added fine particles is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.001 μm or more, preferably 0.005 μm or more, and usually 3 μm or less, preferably 1 μm or less. A plurality of those having different average particle diameters may be blended. The average particle diameter of the externally added fine particles can be determined by observation with an electron microscope, conversion from the value of the BET specific surface area, or the like.
The ratio of the externally added fine particles to the toner is arbitrary as long as the effects of the present invention are not significantly impaired. However, the ratio of the externally added fine particles to the total weight of the toner and the externally added fine particles is usually 0.1% by weight or more, preferably 0.3% by weight or more, more preferably 0.5% by weight or more, and usually 10%. It is desirable that the content is not more than wt%, preferably not more than 6 wt%, more preferably not more than 4 wt%. If the amount of the externally added fine particles is too small, the fluidity and charging stability may be insufficient, and if the amount is too large, the fixability may be deteriorated.

<Toner and others>
The charging characteristics of the toner of the present invention may be negatively charged or positively charged, and can be set according to the type of image forming apparatus used. The charging characteristics of the toner can be adjusted by the selection and composition ratio of toner base particle components such as a charge control agent, the selection and composition ratio of externally added fine particles, and the like.

Further, the toner of the present invention can be used as a one-component developer, or mixed with a carrier and used as a two-component developer.
When used as a two-component developer, the carrier that is mixed with the toner to form the developer may be, for example, a known magnetic substance such as an iron powder, ferrite, or magnetite carrier, or a resin on the surface thereof. A coated one or a magnetic resin carrier can be used.

As the carrier coating resin, for example, generally known styrene resins, acrylic resins, styrene acrylic copolymer resins, silicone resins, modified silicone resins, fluorine resins, and the like can be used. Is not to be done.
The average particle diameter of the carrier is not particularly limited, but those having an average particle diameter of 10 to 200 μm are preferable. These carriers are preferably used in a ratio of 5 to 100 parts by weight with respect to 1 part by weight of the toner.
The formation of a full-color image by electrophotography can be carried out by a conventional method using magenta, cyan, and yellow color toners and, if necessary, black toner.

<Electrophotographic photoreceptor>
The electrophotographic photoreceptor of the present invention has an undercoat layer and a photosensitive layer formed on the undercoat layer on a conductive support. Therefore, the undercoat layer is provided between the conductive support and the photosensitive layer.

Further, as the structure of the photosensitive layer, any structure applicable to a known electrophotographic photoreceptor can be adopted. As a specific example, a so-called single-layer type photoreceptor having a single-layer photosensitive layer (that is, a single-layer type photosensitive layer) in which a photoconductive material is dissolved or dispersed in a binder resin; containing a charge generating substance. Examples include a so-called multilayer photoreceptor having a photosensitive layer (that is, a multilayer photosensitive layer) composed of a plurality of layers formed by laminating a charge generation layer and a charge transport layer containing a charge transport material. In general, it is known that the photoconductive material exhibits the same performance as a function regardless of whether it is a single layer type or a laminated type.
The photosensitive layer of the electrophotographic photosensitive member of the present invention may be in any known form. However, in consideration of the mechanical properties, electrical characteristics, manufacturing stability, etc. of the photosensitive member, A photoreceptor is preferred. In particular, a sequential lamination type photoreceptor in which an undercoat layer, a charge generation layer, and a charge transport layer are laminated in this order on a conductive support is more preferable.
The constituent elements of the electrophotographic photosensitive member of the present invention will be described below with reference to embodiments. However, the constituent elements of the electrophotographic photosensitive member of the present invention are not limited to the following embodiments.

<Underlayer>
As described above, the undercoat layer is a layer containing a binder resin and metal oxide particles.
The thickness of the undercoat layer is arbitrary, but from the viewpoint of improving the photoreceptor characteristics and coating properties of the electrophotographic photoreceptor of the present invention, a range of usually 0.1 μm or more and 20 μm or less is preferable. Further, the undercoat layer may contain additives such as known antioxidants.
The surface layer of the undercoat layer according to the present invention is not limited in its surface shape, but is usually in-plane root mean square roughness (RMS), in-plane arithmetic average roughness (Ra), in-plane maximum roughness (P− V). These numerical values are numerical values obtained by extending the reference length of the root mean square height, arithmetic average height, and maximum height in the standard of JIS B 0601: 2001 to the reference plane, and the height on the reference plane. Using Z (x) which is the value of the direction, the in-plane root mean square roughness (RMS) is the root mean square of Z (x), and the in-plane arithmetic mean roughness (Ra) is Z (x) The average of the absolute values, the in-plane maximum roughness (P-V) represents the sum of the maximum value of the peak height of Z (x) and the maximum value of the valley depth, respectively.

  The in-plane root mean square roughness (RMS) of the undercoat layer according to the present invention is usually in the range of 10 nm or more, preferably 20 nm or more, and usually 100 nm or less, preferably 50 nm or less. If the in-plane Root Mean Square Roughness (RMS) is too small, the adhesion with a layer such as a photosensitive layer formed on the undercoat layer may be deteriorated. There is a possibility that the uniformity of a layer such as a photosensitive layer to be formed is lowered.

  The in-plane arithmetic average roughness (Ra) of the undercoat layer according to the present invention is usually in the range of 10 nm or more, preferably 20 nm or more, and usually 100 nm or less, preferably 50 nm or less. If the in-plane arithmetic average roughness (Ra) is too small, the adhesion with a layer such as a photosensitive layer formed on the undercoat layer may be deteriorated, and if it is too large, it is formed on the undercoat layer. There is a risk that the uniformity of a layer such as a photosensitive layer may be reduced.

  The in-plane maximum roughness (P-V) of the undercoat layer according to the present invention is usually in the range of 100 nm or more, preferably 300 nm or more, and usually 1000 nm or less, preferably 800 nm or less. If the in-plane maximum roughness (P-V) is too small, the adhesion to a layer such as a photosensitive layer formed on the undercoat layer may deteriorate, and if it is too large, it is formed on the undercoat layer. There is a possibility that the uniformity of a layer such as a photosensitive layer is lowered.

  In addition, the numerical value of the index (RMS, Ra, PV) relating to the surface shape can be any surface as long as it is measured by a surface shape analyzer capable of measuring irregularities in the reference plane with high accuracy. Although it may be measured by a shape analyzer, it is preferably measured by a method of detecting irregularities on the sample surface by combining a high-accuracy phase shift detection method and interference fringe order counting using an optical interference microscope. More specifically, it is preferable to measure in the wave mode by the interference fringe addressing method using Micromap of Ryoka System Co., Ltd.

Further, when the undercoat layer according to the present invention is dispersed in a solvent capable of dissolving the binder resin binding the undercoat layer to form a dispersion, the light transmittance of the dispersion has specific physical properties. It is shown. In this case, the light transmittance of the dispersion liquid can also be measured in the same manner as the light transmittance of the coating liquid for forming the undercoat layer of the electrophotographic photosensitive member according to the present invention.
When the undercoat layer according to the present invention is dispersed into a dispersion, the binder resin that binds the undercoat layer is not substantially dissolved, and a photosensitive layer formed on the undercoat layer is used. After dissolving and removing the layer on the undercoat layer with a solvent that can be dissolved, the binder resin that binds the undercoat layer is dissolved in the solvent to obtain a dispersion. At this time, as a solvent that can dissolve the undercoat layer, a solvent that does not have large light absorption in a wavelength region of 400 nm to 1000 nm may be used.

Specific examples of the solvent capable of dissolving the undercoat layer include alcohols such as methanol, ethanol, 1-propanol, and 2-propanol, and particularly methanol, ethanol, and 1-propanol. Moreover, these may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.
The difference between the absorbance with respect to light having a wavelength of 400 nm and the absorbance with respect to light having a wavelength of 1000 nm of a dispersion obtained by dispersing the undercoat layer according to the present invention with a solvent in which methanol and 1-propanol are mixed at a weight ratio of 7: 3 ( The difference in absorbance is as follows. That is, the absorbance difference is preferably 0.3 (Abs) or less, more preferably 0.2 (Abs) or less, when the refractive index of the metal oxide particles is 2.0 or more. Moreover, when the refractive index of a metal oxide particle is less than 2.0, Preferably it is 0.02 (Abs) or less, More preferably, it is 0.01 (Abs) or less.

The absorbance value depends on the solid content concentration of the liquid to be measured. For this reason, when measuring the light transmittance and absorbance, it is preferable to disperse the metal oxide particles in the dispersion so that the concentration thereof is in the range of 0.003% to 0.0075% by weight.
Moreover, the regular reflectance of the undercoat layer according to the present invention usually shows a specific value in the present invention. The regular reflectance of the undercoat layer according to the present invention indicates the regular reflectance of the undercoat layer on the conductive support relative to the conductive support. Since the regular reflectance of the undercoat layer varies depending on the thickness of the undercoat layer, it is defined here as the reflectance when the thickness of the undercoat layer is 2 μm.

In the undercoat layer according to the present invention, when the refractive index of the metal oxide particles contained in the undercoat layer is 2.0 or more, the conductive support is converted when the undercoat layer is 2 μm. The ratio of the regular reflection for light with a wavelength of 480 nm of the undercoat layer to the regular reflection for light with a wavelength of 480 nm is preferably 50% or more.
On the other hand, when the refractive index of the metal oxide particles contained in the undercoat layer is less than 2.0, it is converted to the case where the undercoat layer is 2 μm. The ratio of regular reflection to light having a wavelength of 400 nm of the undercoat layer relative to reflection is preferably 50% or more.

  Here, even when the undercoat layer contains a plurality of types of metal oxide particles having a refractive index of 2.0 or more, or when the undercoat layer contains a plurality of types of metal oxide particles having a refractive index of less than 2.0, Those having regular reflection similar to the above are preferred. In the case where the undercoat layer simultaneously contains metal oxide particles having a refractive index of 2.0 or more and metal oxide particles having a refractive index of less than 2.0, the metal oxide having a refractive index of 2.0 or more As in the case of containing particles, the regular reflection of light of the undercoat layer with respect to light at a wavelength of 480 nm with respect to the light of the conductive support with respect to light of a wavelength of 480 nm as converted when the undercoat layer is 2 μm. The ratio is preferably in the above range (50% or more).

  As described above, the case where the film thickness of the undercoat layer is 2 μm has been described in detail. However, in the electrophotographic photoreceptor according to the present invention, the film thickness of the undercoat layer is not limited to 2 μm, and any film thickness can be obtained. It doesn't matter. When the thickness of the undercoat layer is a thickness other than 2 μm, the coating solution for forming the undercoat layer used for forming the undercoat layer is used and is equivalent to the electrophotographic photosensitive member. An undercoat layer having a thickness of 2 μm can be applied and formed on the conductive support, and the regular reflectance of the undercoat layer can be measured. As another method, there is a method in which the regular reflectance of the undercoat layer of the electrophotographic photosensitive member is measured and converted when the film thickness is 2 μm.

Hereinafter, the conversion method will be described.
Assuming a thin layer of thickness dL perpendicular to the light when specific monochromatic light passes through the subbing layer, is specularly reflected on the conductive support and is again detected through the subbing layer To do.
The amount of decrease in light intensity −dI after passing through a thin layer having a thickness dL is considered to be proportional to the light intensity I before passing through the layer and the thickness dL of the layer. It can be written as follows (k is a constant):

-DI = kIdL (C)
The equation (C) is transformed as follows.
-DI / I = kdL (D)
When both sides of the equation (D) are integrated in the interval from I ₀ to I and from 0 to L, the following equation is obtained. I ₀ is the intensity of incident light.

log (I ₀ / I) = kL (E)
Equation (E) is the same as what is called Lambert's law in a solution system, and can also be applied to the measurement of reflectance in the present invention.
When transforming equation (E),
I = I ₀ exp (−kL) (F)
Thus, the behavior until the incident light reaches the surface of the conductive support is represented by the formula (F).

On the other hand, since the regular reflectance is a denominator of the reflected light of the incident light with respect to the conductive support, the reflectance R = I ₁ / I ₀ on the surface of the raw tube is considered. Here, I ₁ represents the intensity of the reflected light.
Then, the light that has reached the surface of the conductive support according to the formula (F) is regularly reflected after being multiplied by the reflectance R, and again passes through the optical path length L and exits to the surface of the undercoat layer. That is,
I = I ₀ exp (−kL) · R · exp (−kL) (G)
By substituting R = I ₁ / I ₀ and further transforming,
I / I ₁ = exp (-2 kL) (H)
Can be obtained. This is the value of the reflectivity for the undercoat layer relative to the reflectivity for the conductive support, which is defined as the regular reflectivity. As described above, in the undercoat layer of 2 μm, the optical path length is 4 μm in a reciprocating manner, but the reflectivity T of the undercoat layer on any conductive support depends on the thickness L of the undercoat layer (this (Which sometimes becomes an optical path length 2L) and is expressed as T (L). From equation (H):
T (L) = I / I ₁ = exp (−2 kL) (I)
Is established.

On the other hand, since the value we want to know is T (2), substituting L = 2 into the formula (I),
T (2) = I / I ₁ = exp (−4k) (J)
Then, when k is deleted by simultaneous equations (I) and (J),
T (2) = T (L) ^{2 / L} (K)
It becomes. That is, when the thickness of the undercoat layer is L (μm), the reflectance T (2) when the undercoat layer is 2 μm is obtained by measuring the reflectance T (L) of the undercoat layer. It can be estimated with considerable accuracy. The value of the film thickness L of the undercoat layer can be measured by an arbitrary film thickness measuring device such as a roughness meter.

<Photosensitive layer>
-Charge generation material As a charge generation material used for an electrophotographic photosensitive member in the present invention, any material conventionally proposed for use in this application can be used. Examples of such substances are azo pigments, phthalocyanine pigments, anthanthrone pigments, quinacridone pigments, cyanine pigments, pyrylium pigments, thiapyrylium pigments, indigo pigments, polycyclic quinone pigments, squaric acids. And pigments. Particularly preferred are phthalocyanine pigments or azo pigments. The phthalocyanine pigment provides a photosensitive material with high sensitivity to a laser beam having a relatively long wavelength, and the azo pigment has a sufficient sensitivity to white light and a laser beam having a relatively short wavelength. , Each is excellent.
In the present invention, when a phthalocyanine compound is used as the charge generating substance, a high effect is shown and preferable. Specific examples of the phthalocyanine compound include metals such as metal-free phthalocyanine, copper, indium, gallium, tin, titanium, zinc, vanadium, silicon, and germanium, or oxides, halides, hydroxides, alkoxides, and the like. Phthalocyanine and the like.

  The crystal form of the phthalocyanine-based compound is not limited. Particularly, the X-type, τ-type metal-free phthalocyanine, A-type (also known as β-type), B-type (also known as α-type), D, which are highly sensitive crystal types. Type (also called Y type) titanyl phthalocyanine (also known as oxytitanium phthalocyanine), vanadyl phthalocyanine, chloroindium phthalocyanine, chlorogallium phthalocyanine such as type II, hydroxygallium phthalocyanine such as type V, μ-type such as G type and I type Preference is given to oxo-gallium phthalocyanine dimer, μ-oxo-aluminum phthalocyanine dimer such as type II, and the like. Among these phthalocyanines, A-type (β-type), B-type (α-type) and D-type (Y-type) titanyl phthalocyanine, II-type chlorogallium phthalocyanine, V-type hydroxygallium phthalocyanine, G-type μ-oxo-gallium A phthalocyanine dimer and the like are particularly preferable.

  Further, among these phthalocyanine compounds, oxytitanium phthalocyanine having a Bragg angle (2θ ± 0.2 °) of an X-ray diffraction spectrum with respect to CuKα characteristic X-rays of 27.3 ° has a main diffraction peak, 9.3 ° Oxytitanium phthalocyanine showing main diffraction peaks at 13.2 °, 26.2 ° and 27.1 °, at 9.2 °, 14.1 °, 15.3 °, 19.7 ° and 27.1 ° Dihydroxysilicon phthalocyanine with main diffraction peaks, dichloro with main diffraction peaks at 8.5 °, 12.2 °, 13.8 °, 16.9 °, 22.4 °, 28.4 ° and 30.1 ° Tin phthalocyanine, hydroxygallium phthalocyanine showing major diffraction peaks at 7.5 °, 9.9 °, 12.5 °, 16.3 °, 18.6 °, 25.1 ° and 28.3 °, To, 7.4 °, 16.6 °, chlorogallium phthalocyanine preferably exhibits a diffraction peak at 25.5 ° and 28.3 °. Among these, oxytitanium phthalocyanine having a main diffraction peak at 27.3 ° is particularly preferable, and in this case, oxytitanium phthalocyanine having a main diffraction peak at 9.5 °, 24.1 ° and 27.3 ° is particularly preferable. .

In addition, one kind of charge generating substance may be used alone, or two or more kinds may be used in any combination and ratio. Therefore, the phthalocyanine compound may be a single compound or a mixture or mixed crystal of two or more compounds. As the mixed or mixed crystal state of the phthalocyanine compound here, the respective constituent elements may be mixed and used later, or the mixed state in the production / treatment process of the phthalocyanine compound such as synthesis, pigmentation, crystallization, etc. It may be the one that gave rise to. Examples of such treatment include acid paste treatment, grinding treatment, and solvent treatment. There is no limitation on the method for producing the mixed crystal state. For example, as described in JP-A-10-48859, two kinds of crystals are mechanically ground after mixing and made amorphous, and then subjected to solvent treatment. A method of converting to a specific crystal state is mentioned.
In addition, when a phthalocyanine compound is used, a charge generation material other than the phthalocyanine compound may be used in combination. For example, charge generating substances such as azo pigments, perylene pigments, quinacridone pigments, polycyclic quinone pigments, indigo pigments, benzimidazole pigments, pyrylium salts, thiapyrylium salts, and squalium salts can be used in combination.
The charge generating material is dispersed in the photosensitive layer forming coating solution, but may be pre-ground before being dispersed in the photosensitive layer forming coating solution. The pre-grinding can be performed using various apparatuses, but is usually performed using a ball mill, a sand grind mill, or the like. Any grinding media can be used as the grinding media to be fed into these grinding devices as long as the grinding media is not pulverized during the grinding treatment and can be easily separated after the dispersion treatment. Examples thereof include beads and balls such as glass, alumina, zirconia, stainless steel, and ceramics. In the pre-grinding, it is preferred to grind so that the volume average particle diameter is 500 μm or less, more preferably to 250 μm or less. The volume average particle diameter of the charge generating material may be measured by any method commonly used by those skilled in the art, but is usually measured by a normal sedimentation method or a centrifugal sedimentation method.

・ Charge transport materials There are no restrictions on charge transport materials. Examples of charge transport materials include: polymer compounds such as polyvinyl carbazole, polyvinyl pyrene, polyglycidyl carbazole and polyacenaphthylene; polycyclic aromatic compounds such as pyrene and anthracene; indole derivatives, imidazole derivatives, carbazole derivatives, pyrazoles Heterocyclic compounds such as derivatives, pyrazoline derivatives, oxadiazole derivatives, oxazole derivatives, thiadiazole derivatives; p-diethylaminobenzaldehyde-N, N-diphenylhydrazone, N-methylcarbazole-3-carbaldehyde-N, N-diphenylhydrazone, etc. Hydrazone compounds; styryl compounds such as 5- (4- (di-p-tolylamino) benzylidene) -5H-dibenzo (a, d) cycloheptene; triarylamines such as p-tolylamine Compounds; N, N, N ', N'- benzidine compound of tetraphenyl benzidine; butadiene compounds; di - (p-ditolylaminophenyl) triphenylmethane-based compounds such as methane and the like. Among these, a hydrazone derivative, a carbazole derivative, a styryl compound, a butadiene compound, a triarylamine compound, a benzidine compound, or a combination of them is preferably used. These charge transport materials may be used alone or in combination of two or more in any combination and ratio.
Specific examples of suitable structures of the charge transport material are shown below. These specific examples are shown for illustration, and any known charge transporting material may be used as long as it does not contradict the gist of the present invention.

-Binder resin for photosensitive layer The photosensitive layer according to the electrophotographic photosensitive member of the present invention is formed by binding photoconductive materials with various binder resins. As the binder resin for the photosensitive layer, any known binder resin that can be used for an electrophotographic photoreceptor can be used. Specific examples of the binder resin for the photosensitive layer include polymethyl methacrylate, polystyrene, polyvinyl acetate, polyacrylic acid ester, polymethacrylic acid ester, polyester, polyarylate, polycarbonate, polyester polycarbonate, polyvinyl acetal, polyvinyl acetoacetal, polyvinyl propional. , Polyvinyl butyral, polysulfone, polyimide, phenoxy resin, epoxy resin, urethane resin, silicone resin, cellulose ester, cellulose ether, vinyl chloride vinyl acetate copolymer, vinyl chloride such as polyvinyl chloride, and copolymers thereof Used. These partially crosslinked cured products can also be used. In addition, the binder resin for photosensitive layers may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios.

-Layered photoconductor containing charge generation material:
When the electrophotographic photoreceptor of the present invention is a so-called multilayer photoreceptor, the layer containing a charge generating substance is usually a charge generating layer. However, in the multilayer photoconductor, a charge generating material may be included in the charge transport layer as long as the effects of the present invention are not significantly impaired.
There is no restriction on the volume average particle size of the charge generating material. However, when used in a laminated type photoreceptor, the volume average particle diameter of the charge generating material is usually 1 μm or less, preferably 0.5 μm or less. The volume average particle diameter of the charge generation material can be measured in the same manner as the volume average diameter of the metal oxide particles contained in the undercoat layer in the present invention, or a known laser diffraction scattering method. It is also possible to measure with a particle size analyzer by means of, or a particle size analyzer by means of light transmission centrifugal sedimentation.

The thickness of the charge generation layer is arbitrary, but is usually 0.1 μm or more, preferably 0.15 μm or more, and usually 2 μm or less, preferably 0.8 μm or less.
When the layer containing the charge generation material is a charge generation layer, the usage ratio of the charge generation material in the charge generation layer is usually 30 weights with respect to 100 parts by weight of the binder resin for the photosensitive layer contained in the charge generation layer. Part or more, preferably 50 parts by weight or more, and usually 500 parts by weight or less, preferably 300 parts by weight or less. If the amount of the charge generating material used is too small, the electrical characteristics as an electrophotographic photosensitive member may not be sufficient, and if it is too large, the stability of the coating solution may be impaired.

Furthermore, in the charge generation layer, known plasticizers for improving film formability, flexibility, mechanical strength, etc., additives for suppressing residual potential, and dispersion aids for improving dispersion stability Further, it may contain a leveling agent, a surfactant, silicone oil, fluorine oil and other additives for improving coating properties. In addition, these additives may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios.
Single layer type photoreceptor:
When the electrophotographic photosensitive member of the present invention is a so-called single layer type photosensitive member, in the matrix mainly composed of the binder resin for the photosensitive layer and the charge transporting substance having the same mixing ratio as the charge transporting layer described later, The charge generating material is dispersed.

When used in a single-layer type photosensitive layer, it is desirable that the particle size of the charge generating material be sufficiently small. Therefore, in the single-layer type photosensitive layer, the volume average particle diameter of the charge generation material is usually 0.5 μm or less, preferably 0.3 μm or less.
The thickness of the single-layer type photosensitive layer is arbitrary, but is usually 5 μm or more, preferably 10 μm or more, and usually 50 μm or less, preferably 45 μm or less.
The amount of the charge generating material dispersed in the photosensitive layer is arbitrary, but if it is too small, sufficient sensitivity may not be obtained, and if it is too large, chargeability and sensitivity may be lowered. Therefore, the content of the charge generating material in the single-layer type photosensitive layer is usually 0.5% by weight or more, preferably 10% by weight or more, and usually 50% by weight or less, preferably 45% by weight or less.

  In addition, the photosensitive layer of the single-layer type photoreceptor is also a known plasticizer for improving film formability, flexibility, mechanical strength, etc., an additive for suppressing residual potential, and an improvement in dispersion stability. It may contain a dispersion aid, a leveling agent for improving coating properties, a surfactant, silicone oil, fluorine oil and other additives. In addition, these additives may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios.

-Layer containing a charge transport material When the electrophotographic photoreceptor of the present invention is a so-called multilayer photoreceptor, the layer containing a charge transport material is usually a charge transport layer. The charge transport layer may be formed of a resin having a charge transport function alone, but a configuration in which the charge transport material is dispersed or dissolved in a binder resin for a photosensitive layer is more preferable.
The thickness of the charge transport layer is arbitrary, but is usually 5 μm or more, preferably 10 μm or more, more preferably 15 μm or more, and usually 60 μm or less, preferably 45 μm or less, more preferably 27 μm or less.
On the other hand, when the electrophotographic photosensitive member of the present invention is a so-called single layer type photosensitive member, the single layer type photosensitive layer has the charge transport material dispersed or dissolved in the binder resin as a matrix in which the charge generating material is dispersed. Configuration is used.

  As the binder resin used in the layer containing the charge transport material, the above-described binder resin for a photosensitive layer can be used. Among them, examples of those particularly suitable for use in a layer containing a charge transport material include vinyl polymers such as polymethyl methacrylate, polystyrene, and polyvinyl chloride, and copolymers thereof, polycarbonate, polyarylate, polyester, polyester carbonate. , Polysulfone, polyimide, phenoxy, epoxy, silicone resin and the like, and partially crosslinked cured products thereof. In addition, this binder resin may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

In the charge transport layer and the single-layer type photosensitive layer, the ratio of the binder resin and the charge transport material is arbitrary as long as the effect of the present invention is not significantly impaired. Is usually 20 parts by weight or more, preferably 30 parts by weight or more, more preferably 40 parts by weight or more, and usually 200 parts by weight or less, preferably 150 parts by weight or less, more preferably 120 parts by weight or less. The
Furthermore, the layer containing the charge transport material contains various additives such as antioxidants such as hindered phenols and hindered amines, ultraviolet absorbers, sensitizers, leveling agents and electron-withdrawing materials as necessary. Also good. In addition, these additives may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios.

Other layers The electrophotographic photosensitive member of the present invention may have other layers in addition to the undercoat layer and the photosensitive layer described above.
For example, a conventionally known surface protective layer or overcoat layer mainly composed of a thermoplastic or thermosetting polymer may be provided as the outermost surface layer.
-Layer formation method There is no restriction | limiting in the formation method of each layer other than the undercoat layer which a photoreceptor has, Arbitrary methods can be used. For example, as in the case of forming the undercoat layer with the coating solution for forming the undercoat layer of the present invention, a coating solution obtained by dissolving or dispersing the substance contained in the layer in a solvent (for photosensitive layer formation) A coating solution, a coating solution for forming a charge generation layer, a coating solution for forming a charge transport layer, etc.) are sequentially applied and dried by using known methods such as a dip coating method, a spray coating method, a ring coating method, etc. Is done. In this case, the coating solution may contain various additives such as a leveling agent, an antioxidant, and a sensitizer for improving the coating property as necessary.

  Although there is no restriction | limiting in the solvent used for a coating liquid, Usually, an organic solvent is used. Examples of preferable solvents include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-hexanol and 1,3-butanediol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; Ethers such as dioxane, tetrahydrofuran and ethylene glycol monomethyl ether; ether ketones such as 4-methoxy-4-methyl-2-pentanone; (halo) aromatic hydrocarbons such as benzene, toluene, xylene and chlorobenzene; methyl acetate And esters such as ethyl acetate; amides such as N, N-dimethylformamide and N, N-dimethylacetamide; and sulfoxides such as dimethyl sulfoxide. Among these solvents, alcohols, aromatic hydrocarbons, ethers and ether ketones are particularly preferably used. More preferable examples include toluene, xylene, 1-hexanol, 1,3-butanediol, tetrahydrofuran, 4-methoxy-4-methyl-2-pentanone, and the like.

  The said solvent may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio. Examples of solvents that are particularly preferably used in combination of two or more include ethers, alcohols, amides, sulfoxides, ether ketones amides, sulfoxides, ether ketones, among others. Ethers such as 1,2-dimethoxyethane and alcohols such as 1-propanol are suitable. Particularly preferred are ethers. This is particularly from the standpoints of crystal form stabilizing ability and dispersion stability of phthalocyanine when a coating solution is produced using oxytitanium phthalocyanine as a charge generating substance.

In addition, there is no restriction | limiting in the quantity of the solvent used for a coating liquid, What is necessary is just to use an appropriate quantity according to a composition, a coating method, etc. of a coating liquid.
The coating solution for forming a layer is used in the case of a charge transport layer of a single layer type photoreceptor or a multilayer type photoreceptor, and the solid content is usually used in the range of 5 to 40% by weight, but 10 to 35% by weight. It is preferable to use in the range. Moreover, although the viscosity of this coating liquid is normally used in the range of 10-500 mPa * s, it is preferable to set it as the range of 50-400 mPa * s.

In the case of the charge generation layer of the multilayer photoreceptor, the solid content is usually used in the range of 0.1 to 15% by weight, but more preferably in the range of 1 to 10% by weight. Although the viscosity of a coating liquid is normally used in the range of 0.01-20 mPa * s, it is more preferable to be used in the range of 0.1-10 mPa * s.
The coating film is preferably dried by touching at room temperature and then heating and drying in a temperature range of 30 to 200 ° C. for 1 minute to 2 hours with no air or air. The heating temperature may be constant or may be changed while drying.

Advantages of the electrophotographic photosensitive member of the present invention The electrophotographic photosensitive member of the present invention can form high-quality images even under various usage environments. Moreover, it is excellent in durability stability, and image defects such as black spots and color spots are hardly exhibited. Therefore, when the electrophotographic photosensitive member of the present invention is used for image formation, it is possible to form a high-quality image while suppressing the influence of the environment.
Further, in the conventional electrophotographic photosensitive member, the undercoat layer formed by agglomerating metal oxide particles contains a metal oxide particle aggregate that is coarse enough to penetrate the front and back of the undercoat layer. There was a possibility that defects would occur during image formation due to the aggregates of product particles. In addition, when a contact type is used as the charging means, when the photosensitive layer is charged, the charge moves from the conductive support to the photosensitive layer through the metal oxide particles, and the charging is appropriately performed. There was also a risk that it would be impossible. However, since the electrophotographic photosensitive member of the present invention includes an undercoat layer using metal oxide particles having a very small average particle diameter and a good particle size distribution, defects and appropriate charging can be appropriately performed. It is possible to suppress the inability to do so, and high quality image formation is possible.

<Image forming apparatus>
Next, an embodiment of an image forming apparatus using the electrophotographic photosensitive member of the present invention will be described with reference to FIG. However, the embodiment is not limited to the following description, and can be arbitrarily modified without departing from the gist of the present invention.
As shown in FIG. 2, the image forming apparatus includes an electrophotographic photosensitive member 1, a charging device 2, an exposure device 3, a developing device 4, and a transfer device 5, and further includes a cleaning device 6 and a fixing device as necessary. A device 7 is provided.
The electrophotographic photosensitive member 1 is not particularly limited as long as it is the above-described electrophotographic photosensitive member according to the present invention. In FIG. 2, as an example, the above-described photosensitive layer is formed on the surface of a cylindrical conductive support. A drum-shaped photoconductor is shown. A charging device 2, an exposure device 3, a developing device 4, a transfer device 5 and a cleaning device 6 are arranged along the outer peripheral surface of the electrophotographic photosensitive member 1, respectively.

The charging device 2 charges the electrophotographic photosensitive member 1 and uniformly charges the surface of the electrophotographic photosensitive member 1 to a predetermined potential. In FIG. 2, a roller type charging device (charging roller) is shown as an example of the charging device 2, but a corona charging device such as a corotron or scorotron, a contact type charging device such as a charging brush, and the like are often used.
In many cases, the electrophotographic photosensitive member 1 and the charging device 2 are designed to be removable from the main body of the image forming apparatus as a cartridge including both of them (hereinafter referred to as a photosensitive cartridge as appropriate). It is desirable to use in such a form.
In the present invention, as described above, when the charging unit is disposed in contact with the electrophotographic photosensitive member, the effect is remarkably exhibited, so this configuration is desirable.

  For example, when the electrophotographic photoreceptor 1 or the charging device 2 deteriorates, the photoreceptor cartridge can be removed from the image forming apparatus main body, and another new photosensitive cartridge can be mounted on the image forming apparatus main body. ing. Also, the toner described later is often stored in the toner cartridge and designed to be removable from the main body of the image forming apparatus. When the toner in the used toner cartridge runs out, this toner cartridge is removed. It can be removed from the main body of the image forming apparatus and another new toner cartridge can be mounted. Further, a cartridge equipped with all of the electrophotographic photosensitive member 1, the charging device 2, and the toner may be used.

  The type of the exposure apparatus 3 is not particularly limited as long as it can expose the electrophotographic photoreceptor 1 to form an electrostatic latent image on the photosensitive surface of the electrophotographic photoreceptor 1. Specific examples include halogen lamps, fluorescent lamps, lasers such as semiconductor lasers and He—Ne lasers, LEDs, and the like. Further, exposure may be performed by a photoreceptor internal exposure method. The light used for the exposure is arbitrary. For example, the exposure may be performed using monochromatic light having a wavelength of 780 nm, monochromatic light having a wavelength of 600 nm to 700 nm, slightly short wavelength, or monochromatic light having a wavelength of 380 nm to 600 nm. .

  The type of the developing device 4 is not particularly limited, and an arbitrary device such as a dry development method such as cascade development, one-component conductive toner development, two-component magnetic brush development, or a wet development method can be used. In FIG. 2, the developing device 4 includes a developing tank 41, an agitator 42, a supply roller 43, a developing roller 44, and a regulating member 45, and has a configuration in which the toner T is stored inside the developing tank 41. . Further, a replenishing device (not shown) for replenishing the toner T may be attached to the developing device 4 as necessary. The replenishing device is configured to be able to replenish toner T from a container such as a bottle or a cartridge.

The supply roller 43 is formed from a conductive sponge or the like. The developing roller 44 is made of a metal roll such as iron, stainless steel, aluminum, or nickel, or a resin roll obtained by coating such a metal roll with a silicone resin, a urethane resin, a fluorine resin, or the like. The surface of the developing roller 44 may be smoothed or roughened as necessary.
The developing roller 44 is disposed between the electrophotographic photosensitive member 1 and the supply roller 43 and is in contact with the electrophotographic photosensitive member 1 and the supply roller 43, respectively. The supply roller 43 and the developing roller 44 are rotated by a rotation drive mechanism (not shown). The supply roller 43 carries the stored toner T and supplies it to the developing roller 44. The developing roller 44 carries the toner T supplied by the supply roller 43 and contacts the surface of the electrophotographic photosensitive member 1.

  The regulating member 45 is formed by a resin blade such as a silicone resin or a urethane resin, a metal blade such as stainless steel, aluminum, copper, brass, phosphor bronze, or a blade obtained by coating such a metal blade with a resin. The regulating member 45 contacts the developing roller 44 and is pressed against the developing roller 44 side with a predetermined force by a spring or the like (general blade linear pressure is 0.05 to 5 N / cm). If necessary, the regulating member 45 may be provided with a function of imparting charging to the toner T by frictional charging with the toner T.

The agitator 42 is rotated by a rotation driving mechanism, and agitates the toner T and conveys the toner T to the supply roller 43 side. A plurality of agitators 42 may be provided with different blade shapes and sizes.
The type of the toner T is arbitrary as long as the average circularity is 0.940 or more and 1.000 or less. In addition to the pulverized toner, a polymerized toner using a suspension polymerization method or an emulsion polymerization method may be used. Can do. In particular, when a polymerized toner is used, a toner having a small particle diameter of about 4 to 8 μm is preferable, and the toner particles are used in various shapes ranging from a nearly spherical shape to a shape outside the spherical shape on the potato. be able to. The polymerized toner is excellent in charging uniformity and transferability and is suitably used for high image quality.

  The type of the transfer device 5 is not particularly limited, and an apparatus using an arbitrary system such as an electrostatic transfer method such as corona transfer, roller transfer, or belt transfer, a pressure transfer method, or an adhesive transfer method can be used. . Here, it is assumed that the transfer device 5 includes a transfer charger, a transfer roller, a transfer belt, and the like that are disposed to face the electrophotographic photoreceptor 1. The transfer device 5 applies a predetermined voltage value (transfer voltage) having a polarity opposite to the charging potential of the toner T, and transfers the toner image formed on the electrophotographic photosensitive member 1 to a transfer material (paper, medium) P. Is. The present invention is effective when the transfer device 55 is placed in contact with the photoreceptor via a transfer material.

  There is no restriction | limiting in particular about the cleaning apparatus 6, Arbitrary cleaning apparatuses, such as a brush cleaner, a magnetic brush cleaner, an electrostatic brush cleaner, a magnetic roller cleaner, a blade cleaner, can be used. The cleaning device 6 is for scraping off residual toner adhering to the photoreceptor 1 with a cleaning member and collecting the residual toner. However, when there is little or almost no toner remaining on the surface of the photoreceptor, the cleaning device 6 may be omitted.

  The fixing device 7 includes an upper fixing member (fixing roller) 71 and a lower fixing member (fixing roller) 72, and a heating device 73 is provided inside the fixing member 71 or 72. FIG. 2 shows an example in which a heating device 73 is provided inside the upper fixing member 71. As the upper and lower fixing members 71 and 72, a known heat fixing member such as a fixing roll in which a metal base tube such as stainless steel or aluminum is coated with silicon rubber, a fixing roll coated with a fluororesin, or a fixing sheet is used. be able to. Further, each of the fixing members 71 and 72 may be configured to supply a release agent such as silicone oil in order to improve releasability, or may be configured to forcibly apply pressure to each other by a spring or the like.

When the toner transferred onto the recording paper P passes between the upper fixing member 71 and the lower fixing member 72 heated to a predetermined temperature, the toner is heated to a molten state and cooled after passing through the recording paper. Toner is fixed on P.
The type of the fixing device is not particularly limited, and a fixing device of any type such as heat roller fixing, flash fixing, oven fixing, pressure fixing, etc. can be provided including those used here.

In the electrophotographic apparatus configured as described above, an image is recorded as follows. That is, first, the surface (photosensitive surface) of the photoreceptor 1 is charged to a predetermined potential (for example, −600 V) by the charging device 2. At this time, charging may be performed by a DC voltage, or charging may be performed by superimposing an AC voltage on the DC voltage.
Subsequently, the photosensitive surface of the charged photoreceptor 1 is exposed by the exposure device 3 according to the image to be recorded, and an electrostatic latent image is formed on the photosensitive surface. The developing device 4 develops the electrostatic latent image formed on the photosensitive surface of the photoreceptor 1.

The developing device 4 thins the toner T supplied by the supply roller 43 with a regulating member (developing blade) 45 and has a predetermined polarity (here, the same polarity as the charging potential of the photosensitive member 1) and the negative polarity. ), And conveyed while being carried on the developing roller 44 to be brought into contact with the surface of the photoreceptor 1.
When the charged toner T carried on the developing roller 44 comes into contact with the surface of the photoreceptor 1, a toner image corresponding to the electrostatic latent image is formed on the photosensitive surface of the photoreceptor 1. This toner image is transferred onto the recording paper P by the transfer device 5. Thereafter, the toner remaining on the photosensitive surface of the photoreceptor 1 without being transferred is removed by the cleaning device 6.

After the transfer of the toner image onto the recording paper P, the final image is obtained by passing the fixing device 7 and thermally fixing the toner image onto the recording paper P.
In general, the image forming apparatus can be configured to perform, for example, a static elimination process in addition to the above-described configuration, but the image forming apparatus of the present invention does not have a static elimination process. Is the feature.

  Further, the image forming apparatus may be further modified. For example, the image forming apparatus may be configured such that an auxiliary charging process or the like can be performed, offset printing may be performed, or a plurality of types of toner may be used. It is good also as a structure of a full color tandem system.

Hereinafter, the present embodiment will be described more specifically based on examples. In addition, the following examples are shown in order to describe the present invention in detail, and the present invention is not limited to the examples shown below unless it is contrary to the gist thereof. In addition, the description of “parts” in the following production examples, comparative production examples, examples, and comparative examples indicates “parts by weight” unless otherwise specified.
Production Example 1
A rutile type titanium oxide having an average primary particle diameter of 40 nm (“TTO55N” manufactured by Ishihara Sangyo Co., Ltd.) and 3% by weight of methyldimethoxysilane (“TSL8117” manufactured by Toshiba Silicone Co., Ltd.) with respect to the titanium oxide were added to a Henschel mixer. 1 kg of a raw slurry obtained by mixing 50 parts of surface-treated titanium oxide obtained by mixing with 120 parts of methanol, and using a zirconia bead having a diameter of about 100 μm (YTZ manufactured by Nikkato Co., Ltd.) as a dispersion medium, a mill volume of about 0 Using a 15-liter Ultra Apex Mill (UAM-015 type) manufactured by Kotobuki Kogyo Co., Ltd., a titanium oxide dispersion was prepared by dispersing for 1 hour in a liquid circulation state with a rotor peripheral speed of 10 m / second and a liquid flow rate of 10 kg / hour. .

  The titanium oxide dispersion, a mixed solvent of methanol / 1-propanol / toluene, and ε-caprolactam [compound represented by the following formula (A)] / bis (4-amino-3-methylcyclohexyl) methane [the following formula Compound represented by (B)] / Hexamethylenediamine [Compound represented by the following formula (C)] / Decamethylene dicarboxylic acid [Compound represented by the following formula (D)] / Octadecamethylene dicarboxylic acid [Formula (E After the polyamide pellets are dissolved by stirring and mixing the pellets of the copolymerized polyamide having a composition molar ratio of 60% / 15% / 5% / 15% / 5%] , Ultrasonic dispersion using an ultrasonic transmitter with a frequency of 25 kHz and output of 1200 W for 1 hour, and a PTFE membrane with a pore size of 5 μm It is filtered through a filter (Madetex LC manufactured by Advantech), and the weight ratio of the surface-treated titanium oxide / copolymerized polyamide is 3/1, and the weight ratio of the mixed solvent of methanol / 1-propanol / toluene is 7/1/2. Thus, a coating solution A for forming an undercoat layer having a solid content concentration of 18.0% by weight was obtained.

Table 2 below shows the particle size distribution of the coating solution A for forming the undercoat layer measured using the UPA.
The coating liquid A for forming the undercoat layer is dip coated on an anodized aluminum cylinder (outer diameter 30 mm, length 375.8 mm, thickness 0.75 mm), and the film thickness after drying is An undercoat layer was provided so as to be 1.5 μm.

Next, in X-ray diffraction using CuKα rays, a Bragg angle (2θ ± 0.2) shows a strong diffraction peak at 27.3 °, and 10 parts by weight of oxytitanium phthalocyanine having a powder X-ray diffraction spectrum shown in FIG. In addition to 150 parts by weight of 2-dimethoxyethane, pulverization and dispersion treatment was performed with a sand grind mill to prepare a pigment dispersion. 160 parts by weight of the pigment dispersion thus obtained was mixed with 100 parts by weight of a 5% 1,2-dimethoxyethane solution of polyvinyl butyral (trade name # 6000C, manufactured by Denki Kagaku Kogyo Co., Ltd.) and an appropriate amount of 1,2-dimethoxy. In addition to ethane, a dispersion having a solid content concentration of 4.0% was finally produced.
To this dispersion, the aluminum cylinder provided with the undercoat layer was dip coated to form a charge generation layer so that the film thickness after drying was 0.3 μm.
Next, a polycarbonate (PC1: viscosity average molecular weight of about 30,000) having 50 parts of the following compound CT1 as a charge transport material and a repeating unit having the following structure as a binder resin.
M: n = 1: 1) 100 parts,

下記構造を有する酸化防止剤８部、

8 parts of an antioxidant having the following structure:

And a liquid obtained by dissolving 0.05 part of silicone oil (trade name: KF96 Shin-Etsu Chemical Co., Ltd.) as a leveling agent in 640 parts of a tetrahydrofuran / toluene (8/2) mixed solvent, on the charge generation layer, The photosensitive drum A1 having a laminated photosensitive layer was obtained by dip coating so that the film thickness after drying was 18 μm. Further, a photosensitive drum A2 was obtained in the same manner as the photosensitive drum A1, except that the length of the aluminum cylinder was changed to 351 mm.

Production Example 2
Coating liquid B for forming an undercoat layer in the same manner as in Production Example 1 except that zirconia beads having a diameter of about 50 μm (YTZ manufactured by Nikkato Co., Ltd.) were used as a dispersion medium when dispersing with an ultra apex mill. The physical properties were measured in the same manner as in Production Example 1. The results are shown in Table 2 below. The coating solution B for forming this undercoat layer is dip-coated on an anodized aluminum cylinder (outer diameter 30 mm, length 375.8 mm, thickness 1.0 mm), An undercoat layer was provided so that the film thickness after drying was 1.5 μm.
This undercoat layer 94.2 cm ² is immersed in a mixed solution of 70 g of methanol and 30 g of 1-propanol, and subjected to ultrasonic treatment for 5 minutes with an ultrasonic transmitter with an output of 600 W to obtain an undercoat layer dispersion. When the particle size distribution of the metal oxide particles in the liquid was measured by UPA in the same manner as in Example 1, the volume average particle size was 0.08 μm, and the cumulative 90% particle size was 0.12 μm.
On the obtained undercoat layer, a charge generation layer and a charge transport layer were formed in the same manner as in Production Example 1 to obtain a photoreceptor B1. Further, a photosensitive drum B2 was obtained in the same manner as the photosensitive drum B1, except that the length of the aluminum cylinder was changed to 351 mm.

The photosensitive layer 94.2 cm ² of the obtained photoreceptor B1 was immersed in 100 cm ³ of tetrahydrofuran and dissolved and removed by ultrasonic treatment for 5 minutes with an ultrasonic transmitter with an output of 600 W. It is immersed in a mixing solution of 30 g of propanol, and subjected to ultrasonic treatment for 5 minutes with an ultrasonic transmitter having an output of 600 W to obtain an undercoat layer dispersion, and the particle size distribution of the metal oxide particles in the dispersion is shown in Production Example 1 As measured by UPA, the volume average particle size was 0.08 μm, and the cumulative 90% particle size was 0.12 μm.

  From this result, it is possible to dissolve and peel the photosensitive layer from the electrophotographic photosensitive member even if the coating undercoat layer is measured in a solution in which methanol and 1-propanol are mixed in a weight ratio of 7: 3. After that, even if a liquid dispersed in a solvent in which methanol and 1-propanol are mixed at a weight ratio of 7: 3 is measured, data equivalent to the data in Table 2 obtained by measuring the coating solution for forming the undercoat layer itself is collected. I knew it was possible.

Production Example 3
The undercoat layer forming coating solution C was prepared in the same manner as in Production Example 2 except that the rotor peripheral speed during dispersion with the Ultra Apex mill was 12 m / second, and the physical properties were measured in the same manner as in Production Example 1. did. The results are shown in Table 2 below.
A photoconductor C1 was obtained in the same manner as in Production Example 1 except that the undercoat layer forming coating solution C was used. Further, a photosensitive drum C2 was obtained in the same manner as the photosensitive drum C1, except that the length of the aluminum cylinder was changed to 351 mm.
Comparative production example 1
High-speed fluidized mixing of rutile type titanium oxide having an average primary particle size of 40 nm (“TTO55N” manufactured by Ishihara Sangyo Co., Ltd.) and 3% by weight of methyldimethoxysilane (“TSL8117” manufactured by Toshiba Silicone Co., Ltd.) The surface-treated titanium oxide obtained by mixing in a kneading machine (“SMG300” manufactured by Kawata Corporation) and mixing at a high speed at a rotational peripheral speed of 34.5 m / sec is obtained in a methanol / 1-propanol mixed solvent. By dispersing with a 5 mm alumina ball mill, a dispersion slurry of hydrophobized titanium oxide was obtained, and the dispersion slurry, a mixed solvent of methanol / 1-propanol / toluene (weight ratio 7/1/2), and Production Example 1 After stirring and mixing with the copolymerized polyamide pellets used in step 1, the polyamide pellets are dissolved, and then subjected to ultrasonic dispersion treatment. By Nau, we have created a subbing dispersion liquid D having a solid content concentration of 18.0%, containing in a weight ratio of 3/1 hydrophobic-treated titanium oxide / copolymer polyamide.
Except for using the undercoat dispersion D, a photoconductor D1 was obtained in the same manner as in Production Example 1. Further, a photosensitive drum D2 was obtained in the same manner as the photosensitive drum D1, except that the length of the aluminum cylinder was 351 mm.

<Evaluation of electrical characteristics>
The electrophotographic photoreceptors A1 to D1 and A2 to D2 produced in Production Examples 1 to 3 and Comparative Production Example 1 were used as electrophotographic characteristic evaluation devices produced in accordance with Electrophotographic Society standards (secondary electrophotographic technology basics and applications, electronic (Electrical Society edited by Corona, pages 404 to 405), and according to the following procedures, the electrical characteristics were evaluated by a cycle of charging (negative polarity), exposure, potential measurement, and static elimination.
Irradiation energy (half-exposure exposure) when the surface potential becomes -350 V by charging the photosensitive member so that the initial surface potential is -700 V and irradiating the light of the halogen lamp with a monochromatic light of 780 nm with an interference filter. Energy) was measured as sensitivity (E1 / 2) (μJ / cm ² ). Further, the post-exposure surface potential (VL) after 100 ms when the exposure light was irradiated at an intensity of 1.0 μJ / cm ² was measured (−V). Regarding the photoconductors A2 to D2, the layer configuration was the same as that of the photoconductors A1 to D1, and the measured values were the same. The results are shown in Table 3.

表３の結果から、製造例および比較製造例のすべての感光体において、初期的には良好な電気特性を示しており、初期電気特性には差が無いことがわかる。
＜現像用トナーの製造＞
・ワックス・長鎖重合性単量体分散液Ｔ１の調製
パラフィンワックス（日本精鑞社製ＨＮＰ−９、表面張力２３．５ｍＮ／ｍ、融点８２
℃、融解熱量２２０Ｊ／ｇ、融解ピーク半値幅８．２℃、結晶化ピーク半値幅１３．０℃）２７部（５４０ｇ）、ステアリルアクリレート（東京化成社製）２．８部、２０重量％ドデシルベンゼンスルホン酸ナトリウム水溶液（第一工業製薬社製、ネオゲンＳ２０Ａ、以下適宜「２０％ＤＢＳ水溶液」と略称する）１．９部、脱塩水６８．３部を９０℃に加熱してホモミキサー（特殊機化工業社製 マークII ｆモデル）で８０００ｒｐｍの回転数で１０分間攪拌した。

From the results of Table 3, it can be seen that all of the photoreceptors of the production example and the comparative production example show good electrical characteristics in the initial stage, and there is no difference in the initial electrical characteristics.
<Manufacture of developing toner>
Preparation of Wax / Long-Chain Polymerizable Monomer Dispersion T1 Paraffin wax (HNP-9, Nippon Seiki Co., Ltd., surface tension 23.5 mN / m, melting point 82
℃, heat of fusion 220 J / g, melting peak half width 8.2 ° C., crystallization peak half width 13.0 ° C.) 27 parts (540 g), stearyl acrylate (Tokyo Kasei Co., Ltd.) 2.8 parts, 20 wt% dodecyl 1.9 parts of sodium benzenesulfonate aqueous solution (Daiichi Kogyo Seiyaku Co., Ltd., Neogen S20A, hereinafter abbreviated as “20% DBS aqueous solution”) and 68.3 parts of demineralized water were heated to 90 ° C. to homomixer (special The mixture was stirred for 10 minutes at a rotational speed of 8000 rpm using a Mark II f model manufactured by Kika Kogyo Co., Ltd.

Subsequently, this dispersion was heated to 90 ° C., and circulation emulsification was started under a pressure condition of about 25 MPa using a homogenizer (manufactured by Gorin Co., Ltd., 15-M-8PA type), and the volume average particle diameter was UPA-EX. While measuring, the volume average particle size was dispersed to 250 nm to prepare a wax / long-chain polymerizable monomer dispersion T1 (emulsion solid content concentration = 30.2 wt%).
Preparation of silicone wax dispersion T2 27 parts (540 g) of alkyl-modified silicone wax (melting point 72 ° C.), 1.9 parts of 20% DBS aqueous solution, and 71.1 parts of demineralized water were placed in a 3 L stainless steel container and heated to 90 ° C. Then, the mixture was stirred for 10 minutes at a rotation speed of 8000 rpm with a homomixer (Mark II f model, manufactured by Tokushu Kika Kogyo Co., Ltd.).

Next, this dispersion was heated to 99 ° C., and circulation emulsification was started under a pressure condition of about 45 MPa using a homogenizer (manufactured by Gorin Co., Ltd., 15-M-8PA type), and the volume average particle diameter was UPA-EX. A silicone wax dispersion T2 (emulsion solid content concentration = 27.4 wt%) was prepared by dispersing until the volume average particle size was 240 nm while measuring.
-Preparation of polymer primary particle dispersion T1 A reactor equipped with a stirrer (three blades), a heating / cooling device, a concentrating device, and each raw material / auxiliary charging device (inner volume 21 liter, inner diameter 250 mm, height 420 mm) ) 35.6 parts by weight of wax / long-chain polymerizable monomer dispersion T1 (712.12 g) and 259 parts of demineralized water were charged at 90 ° C. under a nitrogen stream while stirring at a rotation speed of 103 rpm. The temperature rose.

  Thereafter, a mixture of the following monomers and an aqueous emulsifier solution was added over 5 hours from the start of polymerization. The time at which the mixture of the monomers and the aqueous emulsifier solution was started to be dropped was set as the polymerization start, and the following initiator aqueous solution was added over 4.5 hours from 30 minutes after the start of the polymerization. The aqueous agent solution was added over 2 hours, and the mixture was further maintained for 1 hour while maintaining the rotation speed of 103 rpm and the internal temperature of 90 ° C.

[Monomers]
Styrene 76.8 parts (1535.0 g)
Butyl acrylate 23.2 parts Acrylic acid 1.5 parts Trichlorobromomethane 1.0 part Hexanediol diacrylate 0.7 part [Emulsifier aqueous solution]
20% DBS aqueous solution 1.0 part Demineralized water 67.1 parts [Initiator aqueous solution]
8% aqueous hydrogen peroxide solution 15.5 parts 8% L (+)-ascorbic acid aqueous solution 15.5 parts [Additional initiator aqueous solution]
8% L (+)-ascorbic acid aqueous solution 14.2 parts After the completion of the polymerization reaction, the mixture was cooled to obtain a milky white primary polymer particle dispersion T1. The volume average particle diameter measured by UPA-EX was 280 nm, and the solid content concentration was 21.1% by weight.
-Preparation of polymer primary particle dispersion T2 A reactor equipped with a stirrer (three blades), a heating / cooling device, a concentrating device, and each raw material / auxiliary charging device (inner volume 21 liter, inner diameter 250 mm, height 420 mm) ) 23.6 parts by weight (472.3 g) of silicone wax dispersion T2, 1.5 parts by weight of 20% DBS aqueous solution, and 324 parts of demineralized water, and heated to 90 ° C. under a nitrogen stream. While stirring at 103 rpm, 3.2 parts of an 8% aqueous hydrogen peroxide solution and 3.2 parts of an 8% L (+)-ascorbic acid aqueous solution were added all at once.

5 minutes later, polymerization of the following mixture of monomers and emulsifier aqueous solution was started (from the time when 3.2 parts of 8% hydrogen peroxide aqueous solution and 3.2 parts of 8% L (+)-ascorbic acid aqueous solution were added all at once. After 5 minutes, the following initiator aqueous solution was added over 6 hours from the start of polymerization, and the mixture was further maintained for 1 hour while maintaining the rotation speed at 103 rpm and the internal temperature of 90 ° C.
[Monomers]
92.5 parts of styrene (1850.0 g)
Butyl acrylate 7.5 parts Acrylic acid 1.5 parts Trichlorobromomethane 0.6 part [Emulsifier aqueous solution]
20% DBS aqueous solution 1. 5 parts Demineralized water 66.2 parts [Initiator aqueous solution]
8% aqueous hydrogen peroxide solution 18.9 parts 8% L (+)-ascorbic acid aqueous solution 18.9 parts After completion of the polymerization reaction, the mixture was cooled to obtain a milky white polymer primary particle dispersion T2. The volume average particle diameter measured by UPA-EX was 290 nm, and the solid content concentration was 19.0% by weight.

・ Preparation of Colorant Dispersion T Manufactured by a furnace method in which a 300 L internal volume container equipped with a stirrer (propeller blade) has an ultraviolet absorbance of 0.02 and a true density of 1.8 g / cm ³ in a toluene extract. Carbon black (Mitsubishi Chemical Corporation, Mitsubishi Carbon Black MA100S) 20 parts (40 kg), 20% DBS aqueous solution 1 part, nonionic surfactant (Kao Co., Emulgen 120) 4 parts, electrical conductivity 2 μS / 75 parts of ion-exchange water of cm was added and predispersed to obtain a pigment premix solution. The conductivity was measured using a conductivity meter (a personal SC meter model SC72 and a detector SC72SN-11 manufactured by Yokogawa Electric Corporation).

The volume cumulative 50% diameter Dv ₅₀ of carbon black in the dispersion after the premix was about 90 μm. The premix solution was supplied as a raw material slurry to a wet bead mill and subjected to one-pass dispersion. The inner diameter of the stator was φ75 mm, the separator diameter was φ60 mm, the distance between the separator and the disk was 15 mm, and zirconia beads having a diameter of 50 μm (true density of 6.0 g / cm ³ ) were used as a dispersion medium. The effective internal volume of the stator is about 0.5 liters, and the media filling volume is 0.35 liters, so the media filling rate is 70%. The rotation speed of the rotor is constant (the peripheral speed of the rotor tip is about 11 m / sec), and the premix slurry is continuously supplied from the supply port by a non-pulsating metering pump at a supply rate of about 50 liters / hr, and from the discharge port. By continuously discharging, a black colorant dispersion T was obtained. The volume average particle diameter measured by UPA-EX was 150 nm, and the solid content concentration was 24.2% by weight.

-Production of developing mother particle T Polymer primary particle dispersion T1 95 parts as solid content (998.2 g as solid content)
Polymer primary particle dispersion T2 5 parts as solid content Colorant fine particle dispersion T 6 parts as colorant solid content 20% DBS aqueous solution 0.1 part as solid content Using each of the above components, toner is prepared according to the following procedure. Manufactured.

Polymer primary particle dispersions T1 and T20 in a mixer (volume 12 liter, inner diameter 208 mm, height 355 mm) equipped with a stirrer (double helical blade), heating / cooling device, concentrating device, and raw material / auxiliary charging device. % DBS aqueous solution was charged and mixed uniformly at an internal temperature of 12 ° C. and 40 rpm for 5 minutes. Subsequently, the stirring rotation speed was increased to 250 rpm at an internal temperature of 12 ° C., and 0.52 part of FeSO ₄ .7H ₂ O as a 5% aqueous solution of ferrous sulfate was added over 5 minutes. Was added uniformly over 5 minutes at an internal temperature of 12 ° C. and kept at 250 rpm, and a 0.5% aqueous solution of aluminum sulfate was added dropwise under the same conditions (the solid content relative to the resin solid content was 0.00). 10 parts). Thereafter, the temperature was raised to 53 ° C. over 75 minutes at 250 rpm, and then raised to 56 ° C. over 170 minutes.

Here, when the particle size was measured with a precision particle size distribution measuring apparatus (multisizer III: manufactured by Beckman Coulter, Inc .; hereinafter abbreviated as “multisizer”) with an aperture diameter of 100 μm, the 50% volume diameter was 6. It was 7 μm.
Thereafter, the polymer primary particle dispersion T2 was added over 3 minutes at 250 rpm, and maintained for 60 minutes. The rotation speed was reduced to 168 rpm, and 20% DBS aqueous solution (6 parts as solid content) was immediately added over 10 minutes. The temperature was raised to 90 ° C. and maintained at 168 rpm for 30 minutes after the addition.

  Thereafter, the slurry obtained by cooling to 30 ° C. over 20 minutes was extracted, and suction filtration was performed with an aspirator using 5 types C (No5C manufactured by Toyo Roshi Kaisha, Ltd.) filter paper. The cake remaining on the filter paper is transferred to a stainless steel container with an internal volume of 10 L (liter) equipped with a stirrer (propeller blade), and 8 kg of ion-exchanged water with an electric conductivity of 1 μS / cm is added and stirred uniformly at 50 rpm. And then left stirring for 30 minutes.

After that, the filter paper is suction filtered with an aspirator again using a filter paper of type 5 C (No. 5C manufactured by Toyo Roshi Kaisha, Ltd.), and the solid matter remaining on the filter paper is again equipped with a stirrer (propeller blade) and has an electric conductivity of 1 μS / cm. It was transferred to a 10 L container with 8 kg of ion-exchanged water, and evenly dispersed by stirring at 50 rpm and kept stirring for 30 minutes. When this process was repeated 5 times, the electrical conductivity of the filtrate was 2 μS / cm. The conductivity was measured using a conductivity meter (a personal SC meter model SC72 and a detector SC72SN-11 manufactured by Yokogawa Electric Corporation).
The cake obtained here was spread on a stainless pad so as to have a height of about 20 mm, and dried in a blow dryer set at 40 ° C. for 48 hours to obtain development mother particles T.

-Production of developing toner T In a Henschel mixer with an internal volume of 10 L (diameter: 230 mm, height: 240 mm) equipped with a stirrer (Z / A ₀ blade) and a deflector oriented perpendicularly to the wall surface from above, the developing mother particle T100 Parts (1000 g), and subsequently 0.5 parts of silica fine particles having a volume average primary particle size of 0.04 μm hydrophobized with silicone oil, and a volume average primary particle size of 0.04 μm hydrophobized with silicone oil. Toner T for development was obtained by adding 2.0 parts of 012 μm silica fine particles, stirring and mixing at 3000 rpm for 10 minutes, and sieving through 150 mesh. The volume average particle diameter of the toner T measured by Multisizer II was 7.05 μm, Dv / Dn was 1.14, and the average circularity measured by FPIA2000 was 0.963.

<Image evaluation>
Example 1
A black drum cartridge for the photoconductor A1 produced in Production Example 1 and the developing toner T for a commercially available tandem LED color printer MICROLINE Pro 9800PS-E (Oki Data Co., Ltd.) capable of A3 printing, Each was mounted on a black toner cartridge, and the cartridge was mounted on the printer.

Specifications of MICROLINE Pro 9800PS-E:
Quadruple tandem color 36ppm, monochrome 40ppm
1200 dpi
Contact roller charging (DC voltage applied)
LED exposure With static elimination light Using this image forming apparatus, a white background image and a gradation image (Japan Imaging Society test chart) were printed out, and the fog value of the white background image and the missing dot in the gradation image were evaluated. The results are shown in Table 4.

To adjust the fog value, adjust the whiteness meter so that the whiteness of the standard sample is 94.4, and measure the whiteness of the paper before printing using this whiteness meter. Then, printing was performed by inputting the signal to the laser printer described above, and then the whiteness of the paper was measured again, and the difference in whiteness before and after printing was determined. A large value means that the printed paper has many fine black spots and is dark, that is, the image quality is poor.
The gradation image is evaluated based on which density standard is printed without missing dots, and the smaller the density value, the better the drawing of the thinner part.

Example 2
Using the photoreceptor B1 of Production Example 2, image evaluation similar to that of Example 1 was performed. The results are shown in Table 4.
Example 3
Using the photoreceptor C1 of Production Example 3, image evaluation similar to that of Example 1 was performed. The results are shown in Table 4.
Comparative Example 1
Using the photoconductor D1 of Comparative Production Example 1, the same image evaluation as in Example 1 was performed. The results are shown in Table 4.
Comparative Example 2
The previously prepared photoreceptor A2 was mounted on a black drum cartridge of a commercially available color printer MICROLINE 3050c (manufactured by Oki Data Corporation) and mounted on the printer. As the toner, a commercially available toner manufactured by the melt kneading and pulverizing method for the printer was used. The average circularity of the toner was 0.935.

Specifications of MICROLINE 3050c:
Quadruple tandem color 21ppm, monochrome 26ppm
1200 dpi
Contact roller charging (DC voltage applied)
LED exposure No static elimination

Comparative Example 3
Image evaluation similar to that of Comparative Example 2 was performed using Photoreceptor B2 of Production Example 2. The results are shown in Table 4.
Comparative Example 4
Image evaluation similar to that of Comparative Example 2 was performed using the photoreceptor C2 of Production Example 3. The results are shown in Table 4.
Comparative Example 5
Using the photoconductor D2 of Comparative Production Example 1, the same image evaluation as in Comparative Example 2 was performed. The results are shown in Table 4.

表４より、比較例２〜５に示されるトナーの円形度が低い画像形成装置では、電子写真感光体の種類に依らず、カブリ値は低い値を確保できるものの、グラデーション画像の描ききれる濃度は十分でなく、解像度が不足している。

According to Table 4, in the image forming apparatuses with low toner circularity shown in Comparative Examples 2 to 5, although the fog value can be kept low regardless of the type of the electrophotographic photosensitive member, the density at which the gradation image can be drawn is Not enough and lacks resolution.

  On the other hand, in the image forming apparatuses using the toner having the average circularity of 0.940 or more in Examples 1 to 3 and Comparative Example 1, only when the electrophotographic photoreceptor having the undercoat layer according to the present invention is used. Although it is possible to draw a low fog value and a sufficient gradation image, in the comparative example 1 using the electrophotographic photosensitive member having a conventionally known undercoat layer, the fog is easily generated and the resolution is high. Also does not rise. As is clear from the evaluation results of the examples, writing exposure is achieved by providing a photosensitive layer on an undercoat layer containing metal oxide particles having a specific particle size distribution, as in the electrophotographic photoreceptor according to the present invention. The latent image can be formed more accurately with light.

It is a longitudinal cross-sectional view which represents typically the structure of the wet stirring ball mill which concerns on this invention. 1 is a schematic diagram illustrating a main configuration of an embodiment of an image forming apparatus of the present invention. It is an X-ray diffraction pattern of oxytitanium phthalocyanine used in an example.

Explanation of symbols

1 Photoconductor 2 Charging device (charging roller)
DESCRIPTION OF SYMBOLS 3 Exposure apparatus 4 Developing apparatus 5 Transfer apparatus 6 Cleaning apparatus 7 Fixing apparatus 14 Separator 15 Shaft 16 Jacket 17 Stator 19 Discharge path 21 Rotor 24 Pulley 25 Rotary joint 26 Raw material slurry supply port 27 Screen support 28 Screen 29 Product slurry extraction port 31 Disk 32 Blade 35 Valve element 41 Developing tank 42 Agitator 43 Supply roller 44 Developing roller 45 Restricting member 71 Upper fixing member (fixing roller)
72 Lower fixing member (fixing roller)
73 Heating device T Toner P Recording paper

Claims (5)

  An electrophotographic photosensitive member, a charging unit for charging the electrophotographic photosensitive member, an image exposing unit for performing image exposure on the charged electrophotographic photosensitive member to form an electrostatic latent image, and the formed electrostatic latent image In an image forming apparatus having a developing unit that develops toner with a toner and a transfer unit that transfers toner to a transfer target, the electrophotographic photosensitive member contains a binder resin and metal oxide particles on a conductive support. The metal oxidation in a liquid having an undercoat layer and a photosensitive layer formed on the layer, the undercoat layer dispersed in a solvent in which methanol and 1-propanol are mixed at a weight ratio of 7: 3. The volume average particle diameter measured by the dynamic light scattering method of the product particles is 0.1 μm or less, the cumulative 90% particle diameter accumulated from the small particle diameter side is 0.3 μm or less, and Average circle measured by flow particle image analyzer An image forming apparatus having a shape of 0.940 or more and 1.000 or less.   The image forming apparatus according to claim 1, wherein the toner is a toner manufactured in an aqueous medium.   The image forming apparatus according to claim 1, wherein the toner has a resin coating layer.     The image forming apparatus according to claim 3, wherein the resin coating layer contains polysiloxane wax.    The image forming apparatus according to claim 1, wherein the toner contains paraffin wax.

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