JP2011100162A - Electrophotographic cartridge, method for forming image by tandem system, and device for image formation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for forming an image with which an image of high gradation and high resolution can be obtained. <P>SOLUTION: The image forming apparatus by a tandem system includes at least a photoreceptor; a toner and an exposure device, wherein the photoreceptor has at least a photosensitive layer on a conductive support, with the toner being obtained by a wet polymerization method, the volume average particle diameter (Dv) of the toner ranging from 3 to 8 μm, and particles having a particle diameter of 0.6 to 2.12 μm measured with a flow type particle image analyzer being included by 3% by number or less of the number of the total number of particles. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming method and an image forming apparatus. More particularly, the present invention relates to an image forming method and apparatus suitable for a printer or an electrophotographic copying machine.

  As copiers and printers using electrophotography have rapidly spread, the demand for high-definition images has increased in recent years. In order to improve high-definition images, particularly gradation and resolution, it is conceivable to increase the number of dots during image exposure. For this purpose, the beam diameter is reduced and the number of output pulses is increased. However, in such high-density recording, the time required to expose one dot is shortened. In such a case, the conventional photoconductor has insufficient photoresponsiveness, and the reproducibility of one dot deteriorates, so that the gradation and resolution are not improved. In order to solve this problem, it is conceivable to increase the light energy itself, but this causes problems such as light fatigue in the photosensitive layer.

  As a method for solving the above-mentioned problem, Japanese Patent Application Laid-Open No. 3-37678 has a strong peak at an X-ray diffraction Bragg angle 2θ of 27.2 ± 0.2 ° with respect to CuKα characteristic X-rays (wavelength 1.541 mm). Disclosed is a method of using the crystalline form of oxytitanyl phthalocyanine as a photoconductive substance for the photosensitive layer, and by using this oxy titanyl phthalocyanine, a photoconductor with high sensitivity and high γ is realized. In the case of using this photoconductor, it has been shown that sufficient dot reproducibility can be realized even when the exposure time of each dot is short in high-density recording.

  In the publication, it is described that a toner having a small particle diameter having an average particle diameter of 8 μm or less is used in combination. That is, even with a small particle size toner, depending on the particle size and particle size distribution of the toner, the fluidity of the toner may be deteriorated, or a non-uniform colorant and charge control agent may be mixed. In some cases, the adhesion on the latent image is not uniform, and the latent image cannot be faithfully reproduced.

JP-A-3-37678 JP 2000-7934 A Japanese Patent Laid-Open No. 11-65235 Japanese Patent Laid-Open No. 11-143125

  The present invention has been made to solve the above-described problems in the prior art. That is, an object of the present invention is to provide a developing method capable of obtaining an image excellent in fine line reproducibility and gradation.

  As a result of intensive studies in view of the above problems, the present inventors have found that the above problems can be solved by a combination of a specific electrophotographic photosensitive member and a toner, and have reached the present invention.

  That is, the gist of the present invention is that, in a tandem type image forming apparatus having at least a photoconductor, a toner, and an exposure device, the photoconductor has at least a photosensitive layer on a conductive support. Obtained by a wet polymerization method, the toner has a volume average particle diameter (Dv) of 3 to 8 μm, and a particle diameter of 0.6 to 2.12 μm measured by a flow type particle image analyzer. The present invention resides in a tandem image forming apparatus characterized in that the number of particles is 3% by number or less of the total number of particles.

  Another gist of the present invention is a particle diameter of 0.6 to 2.12 μm obtained by a wet polymerization method, having a volume average particle diameter (Dv) of 3 to 8 μm and measured by a flow type particle image analyzer. The electrophotographic cartridge includes a toner having 3% by number or less of the total number of particles and a photosensitive member having at least a photosensitive layer on a drum-shaped conductive support having an inner diameter of 16 to 30 mm.

  Another gist of the present invention is an image forming method using at least a photoconductor, an exposure device, and a tandem type image forming apparatus provided with toner, on at least a drum-like conductive support having an inner diameter of 16 to 30 mm. The photosensitive member having a photosensitive layer is subjected to digital image exposure by the exposure device to form an electrostatic latent image on the photosensitive member, and the electrostatic latent image is obtained by a wet polymerization method in developing the electrostatic latent image. A toner having an average particle diameter (Dv) of 3 to 8 μm and particles having a particle diameter of 0.6 to 2.12 μm measured by a flow particle image analyzer is 3% by number or less of the total number of particles is used. The present invention resides in an image forming method.

  In the present invention, a specific titanyl phthalocyanine is used as a photoreceptor and combined with a toner particle size distribution, thereby achieving high gradation and high resolution image formation.

1 is a schematic view of an example of an image forming apparatus used in the present invention. 1 is a schematic view of main components of an example of a tandem type full-color image forming apparatus used in the present invention. In Example A1 and Comparative Example B1, the image analysis result of the thin line image drawn in the vertical direction is shown in the graph. In Example A1 and Comparative Example B1, the image analysis result of the thin line image drawn in the horizontal direction is shown in the graph. In the reference example, the image analysis result of the thin line image drawn in the vertical direction is shown in a graph. In the reference example, the image analysis result of the thin line image drawn in the horizontal direction is shown in a graph.

  Hereinafter, the present invention will be described in detail. First, an outline of the image forming method of the present invention and the image forming apparatus used therefor will be described for an electrophotographic recording apparatus using a non-magnetic one-component toner, which is an example of a full-color image forming method. However, the present invention is limited to this example. Is not to be done. FIG. 1 is a schematic diagram of the main components of an embodiment of an electrophotographic recording apparatus used in the present invention. The photosensitive member 1, the charging device 2, the exposure device 3, the developing device 4, the transfer device 5, the cleaning device 6, And a fixing device 7.

  The photoreceptor 1 is formed of a conductor such as aluminum, and a photosensitive layer is formed by applying a photosensitive conductive material to the outer peripheral surface. 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 photoreceptor 1. The charging device 2 includes, for example, a well-known scorotron charger, a roller charger, and the like, and uniformly charges the surface of the photoreceptor 1 to a predetermined potential. The photosensitive member is preferably provided in a cartridge (photosensitive member cartridge) together with the charging device, and is incorporated in the image forming apparatus. This facilitates replacement when the photoreceptor or the charging device is deteriorated.

  The exposure device 3 exposes the photosensitive surface of the photoreceptor 1 with an LED, laser light, or the like to form an electrostatic latent image on the photosensitive surface of the photoreceptor 1. The developing device 4 includes an agitator 42, a supply roller 43, a developing roller 44, and a regulating member 45, and stores toner T therein. If necessary, the developing device may be provided with a replenishing device (not shown) for replenishing toner, and the replenishing device can replenish toner from containers such as bottles and cartridges.

  The supply roller 43 is made of a conductive sponge or the like and is in contact with the developing roller 44. The developing roller 44 is disposed between the photoreceptor 1 and the supply roller 43. The developing roller 44 is in contact with the photoreceptor 1 and the supply roller 43, respectively. The supply roller 43 and the developing roller 44 are rotated by a rotation drive mechanism. The supply roller 43 carries the stored toner and supplies it to the developing roller 44. The developing roller 44 carries the toner supplied by the supply roller 43 and contacts the surface of the photoreceptor 1.

  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 a metal roll with a silicon resin, a urethane resin, a fluororesin, or the like. The developing roll surface may be smoothed or roughened as necessary. The developing device is preferably incorporated in the image forming apparatus as a toner cartridge including toner. In this way, toner can be easily supplied.

  The restricting member 45 is formed of a resin blade such as silicone resin or urethane resin, a metal blade such as stainless steel, aluminum, copper, brass, phosphor bronze, or a blade obtained by coating a metal blade with resin. The regulating member 45 is in contact with the developing roller 44 and pressed against the developing roller 44 side with a predetermined force by a spring or the like (a general blade linear pressure is 5 to 500 g / cm). The toner may be provided with a function of charging the toner by frictional charging.

  The agitator 42 is rotated by a rotation drive mechanism, respectively, and agitates the toner and conveys the toner to the supply roller 43 side. A plurality of agitators may be provided with different blade shapes and sizes.

  The transfer device 5 includes a transfer charger, a transfer roller, a transfer belt, and the like disposed so as to face the photoreceptor 1. The transfer device 5 applies a predetermined voltage value (transfer voltage) having a polarity opposite to the charging potential of the toner, and transfers the toner image formed on the photoreceptor 1 onto the recording paper P. Depending on the image forming apparatus, there are a case where the toner image on the photosensitive member is directly transferred to the recording paper P and a case where the toner image is transferred to the recording paper P via an intermediate transfer belt (not shown).

  The cleaning device 6 is composed of a cleaning member such as a blade such as urethane and a fur brush, and scrapes the residual toner adhering to the photoreceptor 1 with the cleaning member and collects the residual toner. Depending on the image forming apparatus, a cleaning device may not be provided.

  The fixing device 7 includes an upper fixing member 71 and a lower fixing member 72, and has a heating device 73 inside the upper or lower fixing member. As the fixing member, 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 in which Teflon (registered trademark) resin is coated, or a fixing sheet can be used. Further, a release agent such as silicone oil may be supplied to the fixing member in order to improve the release property. Further, a mechanism for forcibly applying pressure to the upper fixing member and the lower fixing member by a spring or the like may be used.

  When the toner transferred onto the paper P passes between the upper fixing member 71 and the lower fixing member 72 heated to a predetermined temperature, the toner is heated up to a molten state and cooled after passing through the recording paper P. The toner is fixed on the surface.

  In the electrophotographic developing 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. Subsequently, the photosensitive surface of the photoreceptor 1 after being charged 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. Then, development of the electrostatic latent image formed on the photosensitive surface of the photoreceptor 1 is performed by the developing device 4.

  In the developing device 4, the toner supplied by the supply roller 43 is thinned by the developing blade 45 and is triboelectrically charged to a predetermined polarity (here, the same polarity as the charging potential of the photoreceptor 1 and negative polarity). Then, it is carried on the developing roller 44, conveyed, and brought into contact with the surface of the photoreceptor 1.

  A toner image corresponding to the electrostatic latent image is formed on the surface of the photoreceptor 1 from the developing roller 44 by a so-called reversal developing method. The toner image is transferred onto the paper P by the transfer device 5. Thereafter, the toner remaining on the photosensitive surface of the photosensitive member 1 without being transferred is removed by the cleaning device 6. The transferred toner on the recording paper P is passed through the fixing device 7 and thermally fixed, so that a final image is obtained.

  Next, an example of a tandem electrophotographic recording apparatus that uses a non-magnetic one-component toner as a full color will be described. FIG. 2 is a schematic diagram of the main configuration of the full-color tandem system. The photosensitive member 1, the charging device 2, the exposure device 3, the black developing device 4k, the cyan developing device 4c, the yellow developing device 4y, the magenta developing device 4, and the transfer device 5. And a fixing device 7, and the cleaning device is omitted here. A color image can be obtained by adjusting magenta, yellow, cyan, and black toners in multiple layers to a desired color.

  In the case of the tandem method, the color development part located before the black development part may reduce color mixing due to reverse transfer of black toner, and the black development part located behind the color development part is only black. In the case of forming an image with a single color, it is preferable that the color mixture due to the photosensitive member fog of the color toner is reduced, and the speed of black image formation can be increased by transporting the recording paper by short-passing the color developing unit. .

  When the image forming method of the present invention is applied to full color image formation, such a cyan, magenta, and yellow color developing unit is in the front position, and the black developing unit is positioned behind the color developing unit. Is preferred. It should be noted that the order in which the cyan, magenta, and yellow color developing units are positioned can be freely changed in a timely manner.

  The toner used in the present invention contains at least a binder resin and a colorant, and may contain a charge control agent, wax, and other additives as necessary. As a method for producing the toner used in the present invention, a toner produced by a conventional kneading / pulverizing method is produced by a method for increasing the accuracy of a classifier, or a wet polymerization method such as a suspension polymerization method, an emulsion polymerization / aggregation method, or the like. However, it is preferable to use a wet polymerization method in order to efficiently produce the toner of the present invention. Furthermore, an emulsion polymerization / aggregation method is particularly preferred in order to achieve a suitable particle size distribution of the toner of the present invention. The emulsion polymerization / aggregation method has an advantage that the circularity of the toner can be appropriately controlled.

  The binder resin used for the toner can be selected from a wide range including conventionally known ones. Preferably, styrene-based polymers such as styrene-acrylic acid ester copolymers, styrene-methacrylic acid ester copolymers, or acrylic acid copolymers of these resins, saturated or unsaturated polyester polymers, and epoxy polymers. be able to. In addition, the binder resin is not limited to being used alone, but two or more kinds can be used in combination.

  The colorant may be an inorganic pigment, an organic pigment or an organic dye, or a combination thereof. Specific examples of these include carbon black, aniline blue, phthalocyanine blue, phthalocyanine green, Hansa yellow, rhodamine dyes, chrome yellow, quinacridone, benzidine yellow, rose bengal, triallylmethane dye, monoazo, disazo. Any known dyes and pigments such as those based on azo dyes and condensed azo dyes can be used alone or in combination. In the case of a full-color toner, it is preferable to use benzidine yellow as a yellow, monoazo type or condensed azo dye / pigment, quinacridone, monoazo dye / pigment as magenta, and phthalocyanine blue as cyan.

  Among these, as the cyan colorant, C.I. I. Pigment Blue 15: 3, and yellow colorant includes C.I. I. Pigment yellow 74, C.I. I. Pigment Yellow 93 and magenta colorant include C.I. I. Pigment red 238, C.I. I. Pigment red 269, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 48: 2, C.I. I. Pigment Red 122 is preferably used. The addition amount of the colorant is preferably in the range of 2 to 25 parts by weight with respect to 100 parts by weight of the binder resin.

  A charge control agent may be added to the toner used in the present invention in order to impart charge amount and charge stability. Conventionally known compounds are used as the charge control agent. Examples thereof include hydroxycarboxylic acid metal complexes, azo compound metal complexes, naphthol compounds, naphthol compound metal compounds, nigrosine dyes, quaternary ammonium salts, and mixtures thereof. The addition amount of the charge control agent is preferably in the range of 0.1 to 5 parts by weight with respect to 100 parts by weight of the binder resin.

  It is preferable to add wax to the toner used in the present invention in order to impart releasability from the fixing roller or the like. Any wax can be used as long as it has releasability. Specifically, olefin waxes such as low molecular weight polyethylene, low molecular weight polypropylene and copolymer polyethylene; paraffin wax; ester waxes having long chain aliphatic groups such as behenyl behenate, montanate ester, stearyl stearate; hydrogenated Plant waxes such as castor oil carnauba wax; ketones having long chain alkyl groups such as distearyl ketone; silicones having alkyl groups; higher fatty acids such as stearic acid; long chain aliphatic alcohols such as eicosanol; glycerin, pentaerythritol, etc. Examples include carboxylic acid ester or partial ester of polyhydric alcohol obtained from polyhydric alcohol and long chain fatty acid; higher fatty acid amide such as oleic acid amide and stearic acid amide; low molecular weight polyester and the like.

  In order to improve the fixability among these waxes, the melting point of the wax is preferably 30 ° C. or higher, more preferably 40 ° C. or higher, and particularly preferably 50 ° C. or higher. Moreover, 100 degrees C or less is preferable, 90 degrees C or less is still more preferable, and 80 degrees C or less is especially preferable. If the melting point is too low, the wax tends to be exposed and sticky after fixing, and if the melting point is too high, the fixability at low temperatures is poor. Further, the wax compound type is preferably an ester wax obtained from an aliphatic carboxylic acid and a monohydric or polyhydric alcohol. Among the ester waxes, those having 20 to 100 carbon atoms are more preferable, Those of 30 to 60 are particularly preferred.

  Among esters of monohydric alcohol and aliphatic carboxylic acid, particularly preferred compounds include behenyl behenate and stearyl stearate. Among the esters of polyhydric alcohols and aliphatic carboxylic acids, particularly preferred compounds include pentaerythritol stearate and partial esters thereof, glycerin montanate and partial esters thereof.

  The above waxes may be used alone or in combination. Further, the melting point of the wax compound can be appropriately selected depending on the fixing temperature for fixing the toner. The amount of the wax used is usually 0.1 to 40% by weight, preferably 1 to 40% by weight, more preferably 2 to 35% by weight, and particularly preferably 5 to 30% by weight in the toner. Next, a wet polymerization method will be described as a preferred method for producing the toner used in the present invention.

  In the emulsion polymerization / aggregation method, a colorant dispersion, a charge control agent dispersion, a wax dispersion or the like is mixed with a dispersion of polymer primary particles, and these are aggregated by appropriately controlling temperature, salt concentration, pH, and the like. Toner toner is manufactured.

  Examples of the emulsifier used in the emulsion polymerization include at least one emulsifier selected from a cationic surfactant, an anionic surfactant, and a nonionic surfactant. Specific examples of the cationic surfactant include dodecyl ammonium chloride, dodecyl ammonium bromide, dodecyl trimethyl ammonium bromide, dodecyl pyridinium chloride, dodecyl pyridinium bromide, hexadecyl trimethyl ammonium bromide and the like. Specific examples of the anionic surfactant include fatty acid soaps such as sodium stearate and sodium dodecanoate, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, sodium lauryl sulfate and the like. Further, specific examples of nonionic surfactants include polyoxyethylene dodecyl ether, polyoxyethylene hexadecyl ether, polyoxyethylene nonyl phenyl ether, polyoxyethylene lauryl ether, polyoxyethylene sorbitan monooleate ether, monodecanoyl And sucrose. Of these surfactants, alkali metal salts of linear alkylbenzene sulfonic acids are preferred.

  In the suspension polymerization method, a colorant, a charge control agent, wax and the like are mixed with a polymerizable monomer, and dispersion treatment is performed using a disperser such as a disperser. The toner is granulated in a water-miscible medium using a suitable stirrer, and then the polymerizable monomer is polymerized to produce a toner.

  When a suspension stabilizer is used, it is preferable to select a suspension stabilizer that is neutral or alkaline in water and can be easily removed by acid washing after polymerization. Further, it is preferable to select a toner that can obtain a toner having a narrow particle size distribution. Suspension stabilizers that satisfy these requirements include calcium phosphate, tricalcium phosphate, magnesium phosphate, calcium hydroxide, magnesium hydroxide, and the like. Each can be used alone or in combination of two or more. These suspension stabilizers can be used in an amount of 1 to 10 parts by weight based on the radical polymerizable monomer.

  As the polymerization initiator used in the emulsion polymerization / aggregation method and the suspension polymerization method, known polymerization initiators may be used alone or in combination of two or more. For example, potassium persulfate, 2,2′-azobisisobutyronitrile, 2,2′-azobisiso (2,4-dimethyl) valeronitrile, benzoyl peroxide, lauroyl peroxide, or redox initiator is used. I can do it. Of these, redox initiators are preferred in the emulsion polymerization / aggregation method, and azo initiators are preferred in the suspension polymerization method. After the toner is produced by the above method, a toner having a capsule structure may be formed by adding a polymer emulsion, a colorant dispersion, a charge control agent dispersion, a wax dispersion or the like to coat the toner surface.

  Next, the emulsion polymerization / aggregation method, which is the most preferable toner production method of the present invention, will be described in more detail. When a toner is produced by an emulsion polymerization / aggregation method, it usually has a polymerization process, a mixing process, an aggregation process, and a washing / drying process. That is, a dispersion containing polymer primary particles obtained by emulsion polymerization is mixed with a dispersion such as a colorant, a charge control agent, and wax, and the primary particles in the dispersion are aggregated to obtain a volume average particle size of 3 Toner obtained by making particle aggregates of about -8 μm, if necessary, attaching resin fine particles or the like to the particles, and fusing the particle aggregates or particle aggregates to which the resin fine particles are adhered as necessary. The particles are washed and dried to obtain product toner particles.

Polymer primary particles The polymer primary particles used in the emulsion polymerization / aggregation method preferably have a glass transition temperature (Tg) of 40 to 80 ° C. and an average particle size of usually 0.02 to 3 μm. The polymer primary particles are obtained by emulsion polymerization of a monomer.

  In emulsion polymerization, a monomer having a Bronsted acidic group (hereinafter sometimes simply referred to as an acidic group) or a monomer having a Bronsted basic group (hereinafter sometimes simply referred to as a basic group). The polymerization proceeds by adding a monomer having no Bronsted acidic group or Bronsted basic group (hereinafter, also referred to as other monomer). At this time, the monomers may be added separately, or a plurality of monomers may be mixed and added in advance. Further, it is possible to change the monomer composition during the monomer addition. Further, the monomer may be added as it is, or may be added as an emulsified liquid previously mixed and adjusted with water or an emulsifier. As the emulsifier, one or two or more combined systems are selected from the above surfactants.

  Examples of the monomer having a Bronsted acidic group used in the present invention include monomers having a carboxyl group such as acrylic acid, methacrylic acid, maleic acid, fumaric acid and cinnamic acid, and monomers having a sulfonic acid group such as sulfonated styrene. And monomers having a sulfonamide group such as vinylbenzenesulfonamide.

  Examples of the monomer having a Bronsted basic group include aromatic vinyl compounds having an amino group such as aminostyrene, nitrogen-containing heterocycle-containing monomers such as vinylpyridine and vinylpyrrolidone, dimethylaminoethyl acrylate, diethylaminoethyl methacrylate, (Meth) acrylic acid ester having an amino group such as

  Moreover, the monomer which has these acidic groups, and the monomer which has a basic group may exist as a salt with a counter ion, respectively. The blending ratio in the monomer mixture constituting the polymer primary particles of the monomer having a Bronsted acidic group or Bronsted basic group is preferably 0.05% by weight or more, more preferably 1% by weight or more. And preferably 10% by weight or less, more preferably 5% by weight or less. Among the monomers having Bronsted acidic groups or Bronsted basic groups, acrylic acid or methacrylic acid is particularly preferable.

  Other comonomers include styrenes such as styrene, methyl styrene, chlorostyrene, dichlorostyrene, pt-butyl styrene, pn-butyl styrene, pn-nonyl styrene, methyl acrylate, ethyl acrylate , Propyl acrylate, n-butyl acrylate, isobutyl acrylate, hydroxyethyl acrylate, ethyl hexyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, hydroxyethyl methacrylate (Meth) acrylic acid esters such as ethyl hexyl methacrylate, acrylamide, N-propyl acrylamide, N, N-dimethyl acrylamide, N, N-dipropyl acrylamide, N, N-dibutyl acryl De, acrylic acid amide. Can be mentioned. Of these, styrene, butyl acrylate, and the like are particularly preferable.

  Further, when a crosslinked resin is used for the polymer primary particles, a polyfunctional monomer having radical polymerizability is used as a crosslinking agent shared with the above-mentioned monomers, for example, divinylbenzene, hexanediol diacrylate, ethylene glycol diester. Examples include methacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, neopentyl glycol acrylate, diallyl phthalate, and the like. A monomer having a reactive group in a pendant group, such as glycidyl methacrylate, methylol acrylamide, or acrolein, can be used.

  A radically polymerizable bifunctional monomer is preferable, and divinylbenzene and hexanediol diacrylate are more preferable. The blending ratio of such a polyfunctional monomer in the monomer mixture is preferably 0.005% by weight or more, more preferably 0.1% by weight or more, and particularly preferably 0.3% by weight or more. Preferably it is 5 weight% or less, More preferably, it is 3 weight% or less, Most preferably, it is 1 weight% or less.

  These monomers are used alone or in combination, and in this case, the glass transition temperature of the polymer is preferably 40 to 80 ° C. If the glass transition temperature exceeds 80 ° C., the fixing temperature may become too high, or the deterioration of OHP transparency may be a problem. On the other hand, if the glass transition temperature of the polymer is less than 40 ° C., the storage stability of the toner May get worse.

  The polymerization initiator may be added to the polymerization system at any time before, simultaneously with, or after the monomer addition, and these addition methods may be combined as necessary. In the emulsion polymerization, a known chain transfer agent can be used as necessary. Specific examples of such a chain transfer agent include t-dodecyl mercaptan, 2-mercaptoethanol, diisopropyl xanthogen, four Examples thereof include carbon chloride and trichlorobromomethane. The chain transfer agent may be used alone or in combination of two or more, and is used in an amount of 0 to 5% by weight based on the polymerizable monomer. In the emulsion polymerization, the above monomers are mixed with water and polymerized in the presence of a polymerization initiator. The polymerization temperature is usually 50 to 150 ° C, preferably 60 to 120 ° C, more preferably 70 to 100 ° C. .

  The volume average particle diameter of the polymer primary particles thus obtained is usually in the range of 0.02 μm to 3 μm, preferably 0.05 μm to 3 μm, more preferably 0.1 μm to 2 μm, and particularly preferably 0.1 μm to 2 μm. 1 μm to 1 μm. The average particle diameter can be measured using, for example, UPA. If the particle size is smaller than 0.02 μm, it is difficult to control the aggregation rate, which is not preferable. On the other hand, when the particle diameter is larger than 3 μm, the particle diameter of the toner obtained by aggregation tends to be large, which is not suitable for producing a toner having 3 to 8 μm.

In the colorant emulsion polymerization / aggregation method, a dispersion of polymer primary particles and colorant particles are mixed to obtain a mixed dispersion, which is then aggregated to form particle aggregates. The surfactant is preferably emulsified in water and used in the form of an emulsion. The volume average particle size of the colorant particles is preferably 0.01 to 3 μm. The amount of the colorant used is usually 1 to 25 parts by weight, preferably 3 to 20 parts by weight, based on 100 parts by weight of the polymer primary particles.

In the wax emulsion polymerization / aggregation method, it is preferable to use a wax that has been dispersed in advance in the presence of an emulsifier (the surfactant) to give an emulsion. The wax is present in the agglomeration step. For this purpose, the wax fine particle dispersion is co-agglomerated with the polymer primary particles and the colorant particles, and the monomer is seed emulsion polymerized in the presence of the wax fine particle dispersion. In some cases, polymer primary particles encapsulating are produced and the colorant particles are aggregated. Among these, in order to uniformly disperse the wax in the toner, it is preferable that the wax fine particle dispersion be present when the above polymer primary particles are formed, that is, when the monomer is polymerized.

  The average particle diameter of the wax fine particles is preferably 0.01 μm to 3 μm, more preferably 0.1 to 2 μm, and particularly preferably 0.3 to 1.5 μm. The average particle diameter can be measured using, for example, LA-500 manufactured by Horiba. When the average particle size of the wax emulsion is larger than 3 μm, it tends to be difficult to control the particle size during aggregation, and when the average particle size of the emulsion is smaller than 0.01 μm, a dispersion is prepared. Difficult to do.

As a method of incorporating a charge control agent in the charge control agent emulsion polymerization / aggregation method, when obtaining polymer primary particles, the charge control agent is used as a seed simultaneously with the wax, or the charge control agent is dissolved or dispersed in a monomer or wax. Particle size suitable for use as a toner by agglomerating the primary particles of the charge control agent simultaneously with the primary particles of the polymer and the colorant to form particle aggregates, or by agglomerating the primary particles of the polymer and the colorant. Then, the charge control agent primary particles can be added and agglomerated. In this case, the charge control agent is preferably dispersed in water using an emulsifier (the above-mentioned surfactant) and used as an emulsion (primary particles of the charge control agent) having an average particle size of 0.01 to 3 μm.

Mixing step In the agglomeration step of the production method of the present invention, the polymer primary particles, the colorant particles, and the particles of the blending component such as a charge control agent and a wax as necessary are mixed and dispersed simultaneously or sequentially. However, a dispersion of each component, that is, a polymer primary particle dispersion, a colorant particle dispersion, a charge control agent dispersion, and a wax fine particle dispersion, if necessary, are prepared and mixed. It is preferable to obtain a mixed dispersion. The wax is preferably contained in the toner by using the polymer primary particles encapsulated in the polymer primary particles, that is, the polymer primary particles obtained by emulsion polymerization using the wax as a seed. In this case, the polymer primary particles It is possible to use a wax encapsulated in wax and non-encapsulated wax fine particles in combination, but more preferably, substantially the entire amount of wax is encapsulated in polymer primary particles. is there.

Aggregation step In a preferred embodiment of the present invention, the above-mentioned polymer primary particles, colorant primary particles and, if necessary, charge control agent fine particles, wax fine particles and other internal additives are emulsified to form an emulsion, Aggregates to form particle aggregates. Among the components that perform aggregation, the charge control agent dispersion may be added during the aggregation process or after the aggregation process. Here, in the agglomeration step, there are 1) a method of aggregating by heating, and 2) a method of aggregating by adding an electrolyte.

  When the aggregation is carried out by heating, the aggregation temperature is specifically a temperature range of 5 ° C. to Tg (where Tg is the glass transition temperature of the polymer primary particles), and Tg-10 ° C. to Tg-5. A range of ° C is preferred. If it is the said temperature range, it can be made to aggregate to a preferable toner particle size, without using electrolyte. Moreover, when aggregating by heating, when performing an aging process subsequent to the aggregating process, the coagulation process heat and the aging process are continuously performed, and the boundary may be ambiguous, but Tg-20 If there is a step for holding at least 30 minutes in the temperature range of ° C. to Tg, this is regarded as an agglomeration step. The aggregation temperature is preferably kept at a predetermined temperature, usually at least 30 minutes, to obtain toner particles having a desired particle diameter. The temperature may be increased at a constant speed up to a predetermined temperature, or may be increased stepwise. The holding time is preferably 30 minutes or more and 8 hours or less in the range of Tg-20 ° C. to Tg, and more preferably 1 hour or more and less than 4 hours. By doing so, a toner having a small particle size and a sharp particle size distribution can be obtained.

As an electrolyte in the case of performing aggregation by adding an electrolyte to the mixed dispersion, either an organic salt or an inorganic salt may be used, but a monovalent or divalent or higher polyvalent metal salt is preferably used. Specifically, NaCl, KCl, LiCl, Na ₂ SO ₄ , K ₂ SO ₄ , Li ₂ SO ₄ , MgCl ₂ , CaCl ₂ , MgSO ₄ , CaSO ₄ , ZnSO ₄ , Al ₂ (SO ₄ ) ₃ , Fe ₂ (SO ₄ ) ₃ , CH ₃ COONa, C ₆ H ₅ SO ₃ Na, and the like. Of these, inorganic salts having a divalent or higher polyvalent metal cation are more preferred.

  The amount of the electrolyte added varies depending on the type of the electrolyte, but usually 0.05 to 25 parts by weight is used with respect to 100 parts by weight of the solid component of the mixed dispersion. Preferably it is 0.1-15 weight part, More preferably, it is 0.1-10 weight part. When the amount of electrolyte added is significantly less than the above range, the agglomeration reaction proceeds slowly, and fine particles of 1 μm or less remain after the agglomeration reaction, or the average particle diameter of the obtained particle aggregate becomes 3 μm or less. Tend to produce. In addition, when the amount of electrolyte added is significantly larger than the above range, agglomeration that is quick and difficult to control tends to occur, and coarse particles of 25 μm or more are mixed in the obtained particle aggregate, or the shape of the aggregate is irregular. It tends to cause problems such as becoming an irregular shape.

Other Compounding Components Next, in the present invention, it is preferable to form toner particles by coating (adhering or fixing) resin fine particles on the surface of the particle aggregate after the above-described aggregation treatment, if necessary. In addition, when adding the above-described charge control agent after the aggregation treatment, it is preferable to add the resin fine particles after adding the charge control agent to the dispersion containing the particle aggregate.

  The resin fine particles are used as an emulsion dispersed in water or a liquid mainly composed of water using an emulsifier (the above-mentioned surfactant), but the resin fine particles used for the outermost layer of the toner preferably do not contain wax. The resin fine particles preferably have a volume average particle size of 0.02 to 3 μm, more preferably 0.05 to 1.5 μm, and are obtained by polymerizing a monomer similar to the monomer used for the polymer primary particles described above. What was obtained can be used. When the toner is formed by coating the particle aggregate with resin fine particles, the resin used for the resin fine particles is preferably crosslinked.

In the ripening step emulsion polymerization / aggregation method, a range of Tg + 20 ° C. to Tg + 80 ° C. (where Tg is the glass transition temperature of the polymer primary particles) in order to increase the stability of the particle aggregate (toner particles) obtained by aggregation. It is preferable to add an aging step for causing fusion between the aggregated particles. Moreover, it is preferable to hold | maintain in the said temperature range for 1 hour or more in this ripening process. By adding an aging step, the shape of the toner particles can be made nearly spherical and the shape can be controlled. This aging step is usually 1 hour to 24 hours, preferably 1 hour to 10 hours. The particle aggregate before the aging step is considered to be an aggregate due to electrostatic or other physical aggregation of the primary particles, but after the aging step, the polymer primary particles constituting the particle aggregate are fused to each other. And is preferably substantially spherical. In addition, according to such a toner production method, various shapes can be selected depending on the purpose, such as a cocoon type in which primary particles are aggregated, a potato type in which fusion has progressed to the middle, and a spherical shape in which fusion has further progressed. Toner can be produced.

Washing / drying step The particle aggregate obtained through the above steps is subjected to solid-liquid separation according to a known method, and the particle aggregate is recovered, and then washed as necessary and then dried. As a result, desired toner particles can be obtained. In this manner, a toner having a relatively small particle diameter of 3 to 8 μm can be produced. Moreover, the toner thus obtained has a sharp particle size distribution and is suitable as an electrostatic charge image developing toner for achieving high image quality and high speed.

  A known external additive may be added to the toner used in the present invention in order to control fluidity and developability. As the external additive, various inorganic oxide particles such as silica, alumina, titania and the like (hydrophobized if necessary), vinyl polymer particles and the like can be used. The addition amount of the external additive is preferably in the range of 0.05 to 5 parts by weight with respect to the toner particles.

  The toner used in the present invention can be applied to a two-component developer, a magnetic one-component developer such as a magnetite-containing toner, and a non-magnetic one-component developer. When used as a two-component developer, the carrier that is mixed with the toner to form the developer may be a known magnetic substance such as an iron powder type, ferrite type, or magnetite type carrier, or a resin coating on the surface thereof. Or a magnetic resin carrier can be used.

  As the carrier coating resin, generally known styrene resins, acrylic resins, styrene acrylic copolymer resins, silicone resins, modified silicone resins, fluorine resins, and the like can be used, but are not limited thereto. It is not a thing. The average particle size of the carrier is not particularly limited, but preferably has an average particle size of 10 to 200 μm. These carriers are preferably used in an amount of 5 to 100 parts by weight with respect to 1 part by weight of the toner.

  As a method for measuring the particle size of the toner, a commercially available particle size measuring device can be used. Typically, a precision particle size distribution measuring device Coulter Counter Multisizer II manufactured by Beckman Coulter, Inc. is used. The toner used in the present invention has a volume average particle diameter (Dv) of 3 to 8 μm. The volume average particle diameter is preferably 4 to 8 μm, and more preferably 4 to 7 μm. If the volume average particle size is too large, it is not suitable for high-resolution image formation, and if it is too small, handling as a powder becomes difficult.

In the present invention, the toner has a shape as close to a sphere as possible. Specifically, as a method for quantifying the shape of the toner, the toner is measured with a flow type particle image analyzer FPIA-2000 manufactured by Sysmex Corporation, and the cumulative particle size at 50% of the value obtained from the following formula (I). When the circularity corresponding to the value is defined as 50% circularity, a 50% circularity in the range of 0.95 to 1 is used.
(I) Circularity = circumference of a circle having the same area as the particle projection area / perimeter of the particle projection image

  This indicates 50% circularity of the toner and the degree of unevenness of the toner particles, and is 1 when the toner is a perfect sphere. The more complex the surface shape, the smaller the circularity value. The closer to a sphere, the less likely the charge amount is localized in the particle solid and the developability tends to be uniform. Accordingly, the 50% circularity of the toner is more preferably 0.96 or more, and particularly preferably 0.97 or more. Further, since it is difficult to produce a perfect sphere, it is preferably 0.995 or less, more preferably 0.99 or less.

  Further, the sharper toner particle size distribution tends to make the charging property uniform. Specifically, in the image forming method and apparatus of the present invention, the relationship between the volume average particle diameter (Dv) and the number average particle diameter (Dn) is 1.0 ≦ Dv / Dn ≦ 1.3. Is used. The value of Dv / Dn is preferably 1.25 or less, and more preferably 1.20 or less. Moreover, although the lower limit of Dv / Dn is 1, this means that all the particle diameters are equal, and since manufacture is difficult, 1.03 or more are preferable and 1.05 or more are still more preferable.

In order to measure fine particles, for example, a flow type particle image analyzer FPIA-2000 manufactured by Sysmex Corporation is preferably used. In the present invention, a toner in which the measured value (number) of particles of 0.6 μm to 2.12 μm by a flow type particle image analyzer is 15% or less of the total number of particles is preferable. This means that the number of fine particles is less than a certain amount, but the number of particles of 0.6 μm to 2.12 μm is more preferably 10% or less, particularly preferably 5% or less, and most preferably 3% or less. preferable. The lower limit of the fine particles is not particularly limited, and it is most preferable that the fine particles are not present at all. However, it is difficult to produce and is usually 0.05% or more, preferably 0.1% or more. In addition, other indicators of toner with a small amount of fine powder include the following.
1) The toner having a particle diameter of 40% or less of the volume average particle diameter is preferably 9.0 number% or less, and more preferably 8.0 number% or less.
2) The toner having a particle size of 55% or less of the volume average particle size is preferably 5.0% by volume or less, and more preferably 4.0% by volume or less.
3) The toner having a particle size of 55% or less of the volume average particle size is preferably 20% by number or less, and more preferably 16% by number or less.

  Next, the photoconductor used in the present invention will be described. The photoreceptor used in the present invention has at least a photosensitive layer on a conductive support. The photosensitive layer is preferably a laminated type in which a charge generation layer and a charge transfer layer are laminated. The charge generation layer and the charge transfer layer may be provided on the conductive support in the order of the charge generation layer and the charge transfer layer, or may be provided in the order of the charge transfer layer and the charge transfer layer. Of these, a structure in which a charge transfer layer is laminated on the charge generation layer is preferable. In addition to these, an intermediate layer such as an adhesive layer and a blocking layer, and a layer for improving electrical and mechanical properties such as a protective layer may be provided. In the case of a photoreceptor in which a charge generation layer and a charge transfer layer are provided in this order on a support, the intermediate layer is usually between the support and the charge generation layer, and the protective layer is usually a charge transfer layer. Provided on top.

  As the conductive support, any of those used in known electrophotographic photoreceptors can be used. Specific examples include metal drums such as aluminum, stainless steel, and copper, sheets, laminates of these metal foils, and deposits. Furthermore, a plastic film, a plastic drum, a paper, a paper tube, and the like obtained by applying a conductive material such as metal powder, carbon black, copper iodide, and a polymer electrolyte together with an appropriate binder to conduct a conductive treatment. Further, a plastic sheet or drum containing a conductive material such as metal powder, carbon black, or carbon fiber and becoming conductive can be used. Moreover, the plastic film and belt which carried out the electroconductive process with electroconductive metal oxides, such as a tin oxide and an indium oxide, are mentioned. When used in a small and high-speed electrophotographic apparatus, the conductive support is preferably in the form of a drum. In that case, the inner diameter of the drum is usually 10 to 40 mm, preferably 13 to 35 mm, more preferably 16 to 30 mm. It is. Moreover, in the case of a small apparatus, 13-25 mm is especially preferable. In the case of a color electrophotographic apparatus, the above-mentioned small-diameter drum is particularly advantageous when a photoreceptor is used for each of four color toners of cyan, magenta, yellow, and black.

  A blocking layer is provided between the conductive support and the charge generation layer as necessary. As the blocking layer, an alumite layer, a resin undercoat layer (also referred to as an intermediate layer), or a combination of these may be used. Used.

  In the case of providing an alumite layer, it is preferable to use an aluminum substrate as a conductive support, and first, this is degreased by various degreasing cleaning methods such as acid, alkali, organic solvent, surfactant, emulsion, and electrolysis. Next, an anodizing treatment is performed in an acidic bath such as chromic acid, sulfuric acid, oxalic acid, boric acid, sulfamic acid, preferably in a sulfuric acid bath, and an anodized film (alumite layer) is formed. The average film thickness of the anodized film is usually 1 to 20 μm, preferably 1 to 7 μm.

  The obtained anodic oxidation coating can be used as it is, but since it is porous, it is poor in weather resistance and is likely to be corroded, so it is preferable to perform a treatment for sealing those holes, that is, a sealing treatment. Good. As such sealing treatment, low-temperature sealing treatment in which the anodic oxide film formed as described above is immersed in an aqueous solution containing, for example, nickel fluoride as a main component, or an aqueous solution containing, for example, nickel acetate as a main component. A high temperature sealing treatment to be immersed in the inside is performed. The alumite layer formed as described above can be washed by water immersion, water flow, cleaning by jetting water, cleaning by physical contact with a brush-like, foam-like, cloth-like rubbing material, or a combination thereof. A cleaning process is performed, and then a drying process such as air drying or heat drying is performed.

  When an undercoat layer is provided on the conductive support, the binder resin includes polyvinyl methyl ether, poly-N-vinyl imidazole, polyethylene oxide, ethyl cellulose, methyl cellulose, ethylene-acrylic acid copolymer, polyamide, casein, Resin materials such as gelatin, polyethylene, polyester, phenol resin, vinyl chloride-vinyl acetate copolymer, epoxy resin, polyvinyl pyrrolidone, polyvinyl pyridine, polyurethane, polyglutamic acid, polyacrylic acid, and polyamide resin can be used. Of these, a polyamide resin that is excellent in adhesion to the support substrate and has low solubility in the solvent used in the charge generation layer coating solution is preferable.

  The charge generation layer contains at least a binder polymer and a charge generation agent. In the present invention, oxytitanium phthalocyanine is used as the charge generation agent. This may contain an organic photoconductive compound, a dye, an electron withdrawing compound, and the like as necessary. As the binder used in the charge generation layer, polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, vinyl chloride, acrylic acid ester, methacrylic acid ester, vinyl alcohol, ethyl vinyl ether, polyvinyl acetal, polycarbonate, polyester, Examples thereof include polyamide, polyurethane, cellulose ester, cellulose ether, phenoxy resin, silicon resin, and epoxy resin. Of these, polymers and copolymers of vinyl compounds and polyvinyl acetals are preferred. The ratio of the oxytitanium phthalocyanine that is the charge generating agent and the binder polymer is not particularly limited, but is generally 5 to 500 parts by weight, preferably 20 to 300 parts by weight, based on 100 parts by weight of oxytitanium phthalocyanine. Is used.

  One of the features of the present invention is that a specific crystalline oxytitanium phthalocyanine is used as a charge generator. The crystalline oxytitanium phthalocyanine used in the present invention exhibits a clear diffraction peak at a Bragg angle (2θ ± 0.2) of 27.3 ° in X-ray diffraction using CuKα rays. X-ray diffraction is measured by a general Bragg-Brentano concentration method. Usually, the diffraction intensity is expressed in cps.

  This crystalline oxytitanium phthalocyanine is disclosed, for example, in FIG. 2 of Japanese Patent Application Laid-Open No. 62-67094 (referred to as Type II in the same document), FIG. Fig. 1 of JP-A-17066, Fig. 1 of JP-A 63-20365, Journal of Electrophotographic Society Vol. 92 (issued in 1990) No. 3, pages 250-258 (in the same publication, Y-type It is indicated). In this specification, the crystalline oxytitanium phthalocyanine used in the present invention will be referred to as Y-type according to the designation in the academic presentation. According to the Bragg-Brentano concentration method, the Y type is characterized by a maximum diffraction peak at 27.3 °, and is therefore distinguished from the α type and the β type. For example, although the crystal types described in JP-A-3-128973 and JP-A-3-269064 are different in crystallinity, the crystal type is considered to be Y-type. In the Y type, the peak intensity ratio of the peak other than 27.3 ° may change due to its crystallinity, or the peak may be broad and the peak top position may be shifted (this is because the crystal Typically, peaks are shown at 7.4 °, 9.7 °, and 24.2 °. Recently, X-ray diffraction by the transmission method, which eliminates crystal orientation as much as possible, has been performed, and a capillary is used as a sample holder. In the transmission X-ray diffraction by 1.2085 mm, the Y type is Bragg Peaks are shown at angles (2θ ± 0.2) of 21.3 °, 18.9 °, 7.6 °, and 5.8 °. This corresponds to 27.3 °, 24.2 °, 9.7 °, and 7.4 ° by CuKα rays, respectively. In high-resolution X-ray diffraction, the peak corresponding to 9.7 ° is resolved into two or more.

  In the present invention, for the purpose of adjusting sensitivity or the like, a charge generating agent other than Y-type oxytitanium phthalocyanine may be mixed and used, but when mixed, the charge-generating substance is α-type oxytitanium phthalocyanine, If only a titanium-containing phthalocyanine compound such as β-type oxytitanium phthalocyanine is mixed, the proportion of Y-type oxytitanium phthalocyanine in the charge generating agent is usually 30% by weight or more, preferably 50% by weight or more, and 70% by weight. % Or more is more preferable. Further, if mixed with a charge generating agent other than the titanium-containing phthalocyanine compound, the proportion of Y-type oxytitanium phthalocyanine in the charge generating agent is usually 40% by weight or more, preferably 60% by weight or more, and 80% by weight. The above is more preferable.

  The thickness of the charge generation layer is 0.05 to 5 μm, preferably 0.1 to 2 μm. Charge carriers are injected from the charge generation layer. The charge transfer layer contains a carrier transfer medium (charge transfer agent) having high carrier injection efficiency and high transfer efficiency.

  The charge transfer layer contains at least a binder and a charge transfer agent, and if necessary, various additives such as an antioxidant, a sensitizer, a plasticizer, a fluidity imparting agent, and a crosslinking agent. May be. As a charge transfer agent, a high molecular compound having a heterocyclic compound such as poly-N-vinylcarbazole or polystyrylanthracene or a condensed polycyclic aromatic compound in the side chain, and a low molecular compound include pyrazoline, imidazole, oxazole, Hexacyclic compounds such as oxadiazole, triazole, carbazole, triarylalkane derivatives such as triphenylmethane, triarylamine derivatives such as triphenylamine, phenylenediamine derivatives, N-phenylcarbazole derivatives, stilbene derivatives, hydrazone compounds In particular, an electron donating group such as a substituted amino group or an alkoxy group, or a compound having a large electron donating property substituted by an aromatic ring group having these substituents may be mentioned.

  In addition, compounds having an atomic group represented by the following formula (II), formula (III), formula (IV), formula (V), or formula (VI) are also preferably used.

  Specific examples of preferred charge transfer agents are shown below.

  Further, a binder polymer is used in the charge transfer layer as necessary. The binder polymer is preferably a polymer that has good compatibility with the charge transfer agent and does not crystallize or phase-separate the carrier transfer medium after the coating is formed. Examples thereof include styrene, vinyl acetate, chloride. Polymers and copolymers of vinyl compounds such as vinyl, acrylic acid ester, methacrylic acid ester, butadiene, polyvinyl acetal, polycarbonate, polyester, polyarylate, polysulfone, polyphenylene oxide, polyurethane, cellulose ester, cellulose ether, phenoxy resin, silica Examples of the resin include epoxy resin and epoxy resin.

  Preferred binder resins include those containing polycarbonate or polyarylate, although depending on the type of charge transfer agent.

  In the case where the charge transfer agent is a polymer compound, the binder polymer is not particularly required, but mixing may be performed for improving flexibility. In the case of a low molecular compound, a binder polymer is used for film-forming properties, and the amount used is usually 50 to 1000 parts by weight, preferably 100 to 500 parts by weight, based on 100 parts by weight of the charge transfer agent. . In addition to this, various additives for improving the mechanical strength and durability of the coating film can be used for the charge transfer layer. Examples of such additives include known plasticizers, various stabilizers, fluidity imparting agents, and crosslinking agents. The thickness of the charge transfer layer is generally 10 to 60 μm, preferably 15 to 45 μm, and more preferably 27 to 40 μm.

  The above-described undercoat layer, charge generation layer, and charge transfer layer are dissolved or dispersed in an appropriate solvent according to the binder and compounding components used, and are provided by spray coating, spiral coating, ring coating, or dip coating. It is done. In the case of the dip coating method, a coating solution having a total solid content concentration of preferably 25 to 40% and a viscosity of preferably 50 to 300 centipoise, more preferably 100 to 200 centipoise is prepared. As a drying method after coating, a hot air dryer, a steam dryer, an infrared dryer, a far infrared dryer, or the like can be used.

  Next, as an exposure apparatus that performs exposure to form a latent image on the photoconductor, an apparatus that performs digital exposure is used. In consideration of the absorbance of the Y-type oxytitanium phthalocyanine, a laser beam of 500 to 850 nm is used. An exposure apparatus that emits light is preferable. More specifically, an exposure apparatus that emits laser light of around 532 nm, 635 nm, 650 nm, 780 nm, and 830 nm is preferable.

  The reason why the image forming apparatus and method of the present invention exert the above-mentioned effects is not necessarily clear. However, a toner having a 50% circularity of 0.95 to 1 does not have a sharp angle and is nearly circular and has unevenness. Since it has a small shape, it is considered that a latent image with a small dot area is faithfully reproduced. In addition, the adhesion force of toner particles to the electrophotographic photosensitive member (such as mirror image force and van der Waals force) is larger than the Coulomb force applied to the toner particles during transfer, as seen in small particle size toners. The tendency to increase the residual toner can also be solved.

  Furthermore, since such toners have a uniform particle shape, localization of the charge amount within the individual particles due to different particle shapes is unlikely to occur, and as a result, every particle is almost uniform on the photoreceptor. It is considered that the latent image is faithfully reproduced because it adheres with a strong force.

  In addition, by using the above oxytitanium phthalocyanine as a charge generating material for the photoconductor, the photoconductor has high sensitivity and high γ, and this photoconductor exhibits sufficient photoresponsiveness. In particular, the number of dots is 600 dpi or more. Even when the exposure time of each dot increases and the exposure time becomes shorter, development can be performed with a sufficient toner density. Furthermore, the present invention can be effectively applied to a smaller, faster, and higher resolution image forming apparatus. Therefore, the image forming method of the present invention is particularly effective when an image having a resolution of 600 dpi or more, further 1200 dpi or more is formed, and when the rotation speed of the electrophotographic photosensitive member is 1.5 times / second. This is particularly effective, and is particularly effective when the electrophotographic photosensitive member is a drum having an inner diameter of 35 mm or less.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to a following example, unless the summary is exceeded. In the following examples, “parts” means “parts by weight”. The average particle size, weight average molecular weight, glass transition point (Tg), 50% circularity, and melting point of the wax were measured by the following methods.

  Volume average particle size, number average particle size: Measured with LA-500 manufactured by Horiba, Nikkiso Microtrac UPA (ultra particle analyzer), Coulter Counter Multisizer II type (abbreviated as Coulter Counter).

  Weight average molecular weight (Mw): Measured by gel permeation chromatography (GPC) (apparatus: GPC apparatus HLC-8020 manufactured by Tosoh Corporation, column: PL-gel Mixed-B 10μ manufactured by Polymer Laboratory, solvent: THF, sample concentration : 0.1 wt%, calibration curve: standard polystyrene).

  Glass transition temperature (Tg): Measured with DSC7 manufactured by Perkin Elmer (heated from 30 ° C to 100 ° C in 7 minutes, rapidly cooled from 100 ° C to -20 ° C, and increased from -20 ° C to 100 ° C in 12 minutes) And the Tg value observed during the second temperature increase was used).

  Number of particles of 0.6 to 2.12 μm: Measured with a flow particle image analyzer FPIA-2000 manufactured by Sysmex Corporation.

50% circularity: The toner was measured with a flow type particle image analyzer FPIA-2000 manufactured by Sysmex Corporation, and the circularity corresponding to the cumulative particle size value at 50% of the value obtained from the following formula was used.
Circularity = circumference of a circle with the same area as the projected particle area / circumference of the projected particle image

Examples A1 to A3, Comparative Examples B1 to B3
[Manufacture of developing toner-1 (TA1)]
(Wax dispersion-1)
Dehydrated water 68.33 parts, pentaerythritol stearate ester (Unistar H-476, manufactured by NOF Corporation) and stearic stearate ester mixture (UNISTAR M9666, manufactured by NOF Corporation) 7: 3 30 parts mixture, dodecyl 1.67 parts of sodium benzenesulfonate (Neogen SC, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., 66% active ingredient) were mixed and emulsified by applying high-pressure shear at 90 ° C. to obtain a dispersion of ester wax fine particles. The average particle diameter of the ester wax fine particles measured by LA-500 was 340 nm.

(Polymer primary particle dispersion-1)
Reactor (capacity 60 liters, inner diameter 400 mm) equipped with a stirrer (3 blades), heating / cooling device, concentrating device, and raw material / auxiliary charging device 28 parts of wax dispersion-1 and 15% neogen SC aqueous solution 1.2 parts and 393 parts of demineralized water were charged, the temperature was raised to 90 ° C. under a nitrogen stream, and 1.6 parts of an 8% aqueous hydrogen peroxide solution and 1.6 parts of an 8% ascorbic acid aqueous solution were added. Thereafter, a mixture of the following monomers / emulsifier aqueous solution was added over 5 hours from the start of polymerization, and an initiator aqueous solution was added over 6 hours from the start of polymerization, and the mixture was further maintained for 30 minutes.

[Monomers]
79 parts of styrene (5530g)
Butyl acrylate 21 parts Acrylic acid 3 parts Bromotrichloromethane 0.45 parts 2-mercaptoethanol 0.01 parts Hexanediol diacrylate 0.9 parts
[Emulsifier aqueous solution]
15% Neogen SC aqueous solution 1 part Demineralized water 25 parts
[Initiator aqueous solution]
8 parts hydrogen peroxide aqueous solution 9 parts 8% ascorbic acid aqueous solution 9 parts

  After completion of the polymerization reaction, the mixture was cooled to obtain a milky white polymer dispersion. The weight-average molecular weight of the polymer-soluble HTF in the polymer was 127,000, the average particle size measured by UPA was 220 nm, and Tg was unclear.

(Resin fine particle dispersion-1)
5 parts of 15% Neogen SC aqueous solution and 372 parts of demineralized water were added to a reactor (capacity 60 liters, inner diameter 400 mm) equipped with a stirrer (3 blades), heating / cooling device, concentrating device, and raw material / auxiliary charging device The temperature was raised to 90 ° C. under a nitrogen stream, and 1.6 parts of an 8% aqueous hydrogen peroxide solution and 1.6 parts of an 8% ascorbic acid aqueous solution were added. Thereafter, a mixture of the following monomers / emulsifier aqueous solution was added over 5 hours from the start of polymerization, and an initiator aqueous solution was added over 6 hours from the start of polymerization, and the mixture was further maintained for 30 minutes.

[Monomers]
Styrene 88 parts (6160g)
Butyl acrylate 12 parts Acrylic acid 2 parts Bromotrichloromethane 0.5 part 2-mercaptoethanol 0.01 part Hexanediol diacrylate 0.4 part
[Emulsifier aqueous solution]
15% Neogen SC aqueous solution 2.5 parts Demineralized water 24 parts
[Initiator aqueous solution]
8 parts hydrogen peroxide aqueous solution 9 parts 8% ascorbic acid aqueous solution 9 parts

  After completion of the polymerization reaction, the mixture was cooled to obtain a milky white polymer dispersion. The polymer had a THF-soluble component weight average molecular weight of 54,000, an average particle size measured by UPA of 83 nm, and Tg of 85 ° C.

(Colorant fine particle dispersion-1)
Pigment Blue 15: 3 aqueous dispersion (EP-700 BlueGA, manufactured by Dainichi Seika Co., Ltd., solid content 35%) The average particle size measured by UPA was 150 nm.

Production of toner for development-1
Polymer primary particle dispersion-1 103 parts (2773 g: as solid content)
Resin fine particle dispersion-1-5 parts (as solid content)
Colorant fine particle dispersion-1 6.7 parts (as solid content)
0.5 parts of 15% Neogen SC aqueous solution (as solids)

  Using each of the above components, a toner was produced by the following procedure. The polymer primary particle dispersion and 15% Neogen SC aqueous solution were charged into a reactor (capacity 60 liters, anchor blade with baffle) and mixed uniformly, and then the colorant fine particle dispersion was added and mixed uniformly. While stirring the obtained mixed dispersion, an aqueous aluminum sulfate solution was added dropwise (0.6 parts as a solid content). Thereafter, while stirring, the temperature was raised to 50 ° C. over 25 minutes and held for 1 hour, and further heated to 60 ° C. over 15 minutes and held for 1 hour and 35 minutes. A resin fine particle dispersion and an aqueous aluminum sulfate solution (0.07 part as solid content) were added in this order, and the temperature was raised to 62 ° C. over 5 minutes and held for 30 minutes. After adding 15% Neogen SC aqueous solution (3 parts as solid content), the temperature was raised to 96 ° C. over 50 minutes and held for 3 hours. Thereafter, it was cooled, filtered, washed with water, and dried to obtain a toner.

To 100 parts of this toner, 0.6 part of hydrophobic surface-treated silica was mixed and stirred to obtain a developing toner (TA1).
Toner Evaluation-1
The volume average particle diameter of the developing toner (TA1) by Coulter counter is 7.2 μm, the ratio of the particle diameter of 5 μm or less is 2.5%, the ratio of 15 μm or more is 0.8%, and the particle diameter is 0.6-2. The ratio of the number of particles of 12 μm is 0.39%, the ratio of the particle diameter of 55% or less of the volume average particle diameter is 0.39% by volume and 2.12%, the ratio of the particle diameter of 40% or less of the volume average particle diameter Was 1.37% by number. Dv / Dn = 1.13, and the 50% circularity was 0.95.

[Manufacture of developing toner-2 (TA2)]
(Wax dispersion-2)
Dehydrated water 68.33 parts, ester mixture mainly composed of behenyl behenate (Unistar M-2222SL, manufactured by Nippon Oil & Fats) and ester mixture mainly composed of stearyl stearate (Unistar M9676, manufactured by Nippon Oil & Fats) 7: 3 mixture 30 1 part of sodium dodecylbenzenesulfonate (Neogen SC, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., 66% active ingredient) was mixed and emulsified by applying high-pressure shearing at 90 ° C. to obtain a dispersion of ester wax fine particles. . The average particle diameter of the ester wax fine particles measured by LA-500 was 240 nm.
(Polymer primary particle dispersion-2)
Reactor (capacity 60 liters, inner diameter 400 nm) equipped with a stirrer (three blades), heating / cooling device, concentrating device, and raw material / auxiliary charging device 28 parts of wax dispersion-2, 15% neogen SC aqueous solution 1.2 parts and 393 parts of demineralized water were added, the temperature was raised to 90 ° C. under a nitrogen stream, and 1.6 parts of an 8% aqueous hydrogen peroxide solution and 1.6 parts of an 8% ascorbic acid aqueous solution were added. Thereafter, a mixture of the following monomers / emulsifier aqueous solution was added over 5 hours from the start of polymerization, and an initiator aqueous solution was added over 6 hours from the start of polymerization, and the mixture was further maintained for 30 minutes.

[Monomers]
Styrene 79 parts Butyl acrylate 21 parts Acrylic acid 3 parts Bromotrichloromethane 0.45 parts 2-mercaptoethanol 0.01 parts Hexanediol diacrylate 0.9 parts
[Emulsifier aqueous solution]
15% Neogen SC aqueous solution 1 part Demineralized water 25 parts
[Initiator aqueous solution]
8 parts hydrogen peroxide aqueous solution 9 parts 8% ascorbic acid aqueous solution 9 parts

After completion of the polymerization reaction, the mixture was cooled to obtain a milky white polymer dispersion. The polymer had a THF-soluble component weight average molecular weight of 148,000, an average particle size measured by UPA of 207 nm, and Tg of 55 ° C.
(Resin fine particle dispersion-2)
The same resin fine particle dispersion-1 was used.
(Colorant fine particle dispersion-2)
20 parts of Pigment Yellow 74, 7 parts of polyoxyethylene alkylphenyl ether and 73 parts of demineralized water were dispersed in a sand grinder mill to obtain a colorant fine particle dispersion. The average particle size measured by UPA was 211 nm.
(Charge control agent fine particle dispersion-2)
4,4′-methylenebis [2- [N- (4-chlorophenyl) amide] -3-hydroxynaphthalene] (compound CCA-1 having the following structure) 20 parts, alkylnaphthalene sulfonate 4 parts, demineralized water 76 parts Dispersion was performed with a sand grinder mill to obtain a charge control agent fine particle dispersion. The average particle size measured by UPA was 200 nm.

Production toner 2
Polymer primary particle dispersion-2 105 parts (as solids)
Resin fine particle dispersion-1-5 parts (as solid content)
Colorant fine particle dispersion-2 6.7 parts (as solid content)
Charge control agent fine particle dispersion-2-2 parts (as solid content)

  Using each of the above components, a toner was produced by the following procedure. The polymer primary particle dispersion and the colorant fine particle dispersion were charged into a reactor (volume: 1 liter, anchor blade with baffle) and mixed uniformly. While stirring the obtained mixed dispersion, an aqueous aluminum sulfate solution was added dropwise (0.6 parts as a solid content). Thereafter, while stirring, the temperature was raised to 51 ° C. over 25 minutes and held for 1 hour, and further heated to 59 ° C. over 8 minutes and held for 40 minutes. A charge control agent fine particle dispersion, a resin fine particle dispersion, and an aqueous aluminum sulfate solution (0.07 parts as a solid content) were added in this order, and the temperature was raised to 61 ° C. over 15 minutes and held for 30 minutes. After adding 15% neogen SC aqueous solution (3.8 parts as a solid content), the temperature was raised to 96 ° C. over 30 minutes and held for 4 hours. Thereafter, it was cooled, filtered, washed with water, and dried to obtain a toner. To 100 parts of this toner, 0.6 part of hydrophobic surface-treated silica was mixed and stirred to obtain a developing toner (TA2).

Toner Evaluation-2
The volume average particle diameter of the developing toner (TA2) by Coulter counter is 7.5 μm, the ratio of the particle diameter of 5 μm or less is 1.6%, the ratio of 15 μm or more is 0.7%, and the particle diameter is 0.6-2. The ratio of the number of particles of 12 μm is 0.46%, the ratio of the particle diameter of 55% or less of the volume average particle diameter is 0.26% by volume and 2.8% by number, and the ratio of the particle diameter of 40% or less of the volume average particle diameter Was 1.29% by number. Further, Dv / Dn = 1.14, and the 50% circularity was 0.96.

[Manufacturing of developing toner-3 (TA3)]
(Wax dispersion-3)
What was manufactured like wax dispersion liquid-2 was used. The average particle diameter of the ester wax fine particles measured by LA-500 was 340 nm.
(Polymer primary particle dispersion-3)
A wax fine particle dispersion-3 was used which was produced in the same manner as the polymer primary particle dispersion-2. The weight-average molecular weight of the polymer soluble in THF was 119,000, the average particle size measured by UPA was 189 nm, and Tg was 57 ° C.
(Resin fine particle dispersion-3)
The same resin fine particle dispersion-1 was used.
(Colorant fine particle dispersion-3)
20 parts of Pigment Red 238 (compound of the following formula (A)), 2.5 parts of alkylbenzene sulfonate, and 77.5 parts of demineralized water were dispersed in a sand grinder mill to obtain a colorant fine particle dispersion. The average particle size measured by UPA was 181 nm.

(Charge control agent fine particle dispersion-3)
The same charge control agent fine particle dispersion-2 was used.
Production of toner for development-3
Polymer primary particle dispersion-3 104 parts (as solids)
Resin fine particle dispersion-1 6 parts (as solid content)
Colorant fine particle dispersion-3 6.7 parts (as solid content)
Charge control agent fine particle dispersion-2-2 parts (as solid content)
0.65 parts of 15% Neogen SC aqueous solution (as solids)

  Using each of the above components, a toner was produced by the following procedure. The polymer primary particle dispersion and 15% neogen SC aqueous solution were charged into a reactor (capacity 1 liter, anchor blade with baffle) and mixed uniformly, and then the colorant fine particle dispersion was added and mixed uniformly. While stirring the obtained mixed dispersion, an aqueous aluminum sulfate solution was added dropwise (0.8 parts as a solid content). Thereafter, while stirring, the temperature was raised to 51 ° C. over 15 minutes and held for 1 hour, and further heated to 59 ° C. over 6 minutes and held for 20 minutes. A charge control agent fine particle dispersion, a resin fine particle dispersion, and an aluminum sulfate aqueous solution (0.09 parts as a solid content) were added in this order, and the mixture was held at 59 ° C. for 20 minutes. After adding 15% Neogen SC aqueous solution (3.7 parts as solid content), the temperature was raised to 95 ° C. over 25 minutes, and further 15% Neogen SC aqueous solution (0.7 parts as solid content) was added. For 3.5 hours. Thereafter, it was cooled, filtered, washed with water, and dried to obtain a toner.

To 100 parts of this toner, 0.6 part of hydrophobic surface-treated silica was mixed and stirred to obtain a developing toner (TA3).
Toner Evaluation-3
The volume average particle diameter of the developing toner (TA3) by Coulter counter is 7.8 μm, the ratio of the volume particle diameter of 5 μm or less is 2.1%, the ratio of 15 μm or more is 2.1%, and the particle diameter is 0.6-2. The ratio of the number of particles of .12 μm is 0.80%, the ratio of the particle diameter of 55% or less of the volume average particle diameter is 0.51% by volume, and the ratio of the particle diameter of 40% or less of the volume average particle diameter is 1.85. %Met. Further, Dv / Dn = 1.15, and the 50% circularity was 0.97.

(Photosensitive member production example-1)
(Alumite layer)
A 30 mm diameter, 340 mm long, 1 mm thick aluminum cylinder having a mirror-finished surface was degreased and washed at 60 ° C. for 5 minutes in a 30 g / l aqueous solution of NC- # 30 (manufactured by Kizai Co., Ltd.). . Subsequently, it was washed with water and then immersed in 7% nitric acid at 25 ° C. for 1 minute. Further, after rinsing with water, anodization was performed at a current density of 1.2 A / dm ^{2 in} a 180 g / l sulfuric acid electrolyte (dissolved aluminum concentration 7 g / l) to form an anodized film having an average film thickness of 6 μm. Next, after water washing, sealing treatment was performed by immersing in a 10 g / l aqueous solution of a high temperature sealant top seal DX-500 (manufactured by Hadano Pharmaceutical Co., Ltd.) mainly composed of nickel acetate at 95 ° C. for 30 minutes. Subsequently, after washing with water, the entire surface of the coating was reciprocated three times using a polyester sponge and rubbed. Then it was washed with water and dried.

(Undercoat layer)
Ishihara Sangyo Co., Ltd., product name TTO-55N (crystal type rutile primary particle size 0.03-0.05 μm), mixed alcohol (methanol / 1-propanol = 70/30) as titanium oxide, dispersed for 16 hours with a ball mill did. The titanium oxide dispersion obtained here was added to a mixed alcohol (methanol / 1-propanol = 70/30) solution of the following polyamide resin (PA-1). Finally, a dispersion having a titanium oxide / nylon ratio of 1/1 (weight ratio) and a solid concentration of 16% was prepared, and this was used as a dispersion for an undercoat layer.

The drum (aluminum cylinder) was dip-coated in the undercoat layer dispersion, and an undercoat layer was provided so that the dry film thickness was 0.75 μm.
(Charge generation layer)
Production of β-type oxytitanium phthalocyanine (β-type TiOPc) 97.5 g of phthalodinitrile is added to 750 ml of α-chloronaphthalene, and then 22 ml of titanium tetrachloride is added dropwise under a nitrogen atmosphere. After dropping, the temperature was raised, and the mixture was reacted at 200 to 220 ° C. for 3 hours with stirring, then allowed to cool, filtered hot at 100 to 130 ° C., and washed with 200 ml of α-chloronaphthalene heated to 100 ° C. Furthermore, the hot-washing process (100 degreeC, 1 hour) was performed 3 times with 200 ml N-methylpyrrolidone. Subsequently, the suspension was washed with 300 ml of methanol at room temperature, and further washed with 500 ml of methanol for 1 hour. According to the X-ray diffraction of the oxytitanium phthalocyanine thus obtained, there is no substantial peak at 4 ° to 8 ° at a black angle (2θ ± 0.2 °), 9.3 °, 10. There are clear diffraction peaks at 6 °, 13.2 °, 15.1 °, 15.7 °, 16.1 °, 20.8 °, 23.3 °, 26.3 ° and 27.1 °. Of these, the peak at 26.3 ° is the strongest.

  -Manufacture of Y-type oxytitanium phthalocyanine (Y-type TiOPc) The β-type oxytitanium phthalocyanine obtained by the above-mentioned process is ground in a sand grind mill for 20 hours, followed by 400 ml of water and 40 ml of orthodichlorobenzene. And heat-treated at 60 ° C. for 1 hour. According to the X-ray diffraction of the oxytitanium phthalocyanine thus obtained (Bragg-Brenter's concentration method), the black angle (2θ ± 0.2 °) is maximum at 27.3 ° and has a sharp peak. Indicated.

  Further, the Y-type oxytitanium phthalocyanine thus obtained was subjected to transmission X-ray diffraction at 1.2085 mm using a capillary as a sample holder. As a result, the Bragg angle (2θ ± 0.2 °) 21.3 ° (100 (However, the parentheses are relative intensities when the peak intensity at 21.3 ° is taken as 100), 18.9 ° (13), 14.1 ° (12), 11.8 ° (14), 11. Diffraction peaks were observed at 1 ° (11), 9.2 ° (11), 7.6 ° (36), 7.4 ° (25), and 5.8 ° (8). The measuring device is a multi-detector powder X-ray diffractometer. The details of the device are “Radiotron Powder Diffraction Experiment Station (BL-4B) Design Report, (1995), KEK” published by High Energy Physics Laboratory. Report 94-11 ". Measurement conditions are a step angle of 0.005 °, 4.5 seconds / step, and a d-value calculation wavelength = 1.2085 mm.

  -Preparation and application of coating solution for charge generation layer 10 parts of Y-type TiOPc obtained in the above production example was added to 150 parts by weight of 4-methoxy-4-methylpentanone-2, and pulverized and dispersed in a sand grind mill Processed. Moreover, 5% of 5% 1,2-dimethoxyethane solution of polyvinyl butyral (manufactured by Denki Kagaku Kogyo Co., Ltd., trade name Denkabutyral # 6000C) and 5% of phenoxy resin (trade name PKHH, manufactured by Union Carbide) 1, A binder solution was prepared by mixing 100 parts of a 2-dimethoxyethane solution. 100 parts by weight of the binder solution and an appropriate amount of 1,2-dimethoxyethane were added to 160 parts by weight of the previously prepared pigment dispersion to finally prepare a dispersion having a solid content concentration of 4.0%. The dispersion thus obtained was further applied by dip coating on the aluminum drum coated with the undercoat layer to form a charge generation layer having a thickness of 0.2 μm.

(Charge transfer layer)
Next, 45 parts of the following charge transfer material (TAPC) and 100 parts of polycarbonate resin (m: n = 51: 49, viscosity average molecular weight 30,000) represented by the following structural formula, 4-methyl-2,6- 16 parts of di-t-butylphenol and 0.03 part of silicone oil (manufactured by Shin-Etsu Silicone, KF-96) were dissolved in a mixed solvent of 170 parts of dioxane and 400 parts of tetrahydrofuran to prepare a coating solution. This was further dip-coated on an aluminum drum coated with the undercoat layer and the charge generation layer to provide a charge transfer layer so that the film thickness after drying at 125 ° C. for 20 minutes was 20 μm. This is a photoreceptor “PC-A1”.

(Manufacture of photoconductor-2)
The production up to the alumite layer, undercoat layer, and charge generation layer was carried out in the same manner as in Production Example 1 of the photoreceptor.
(Charge transfer layer)
Next, 60 parts of the charge transfer material of the structural formula (D-2), 100 parts of polycarbonate resin represented by the following structural formula, 6 parts of 4-methyl-2,6-di-t-butylphenol, and silicone oil (Shin-Etsu Silicone) Manufactured, KF-96) 0.03 part was dissolved in a mixed solvent of 170 parts of dioxane and 400 parts of tetrahydrofuran to prepare a coating solution. This was further dip-coated on an aluminum drum coated with the undercoat layer and the charge generation layer to provide a charge transfer layer so that the film thickness after drying at 125 ° C. for 20 minutes was 20 μm. This is a photoreceptor “PC-A2”.

(Photoconductor Production Example-3)
The production up to the alumite layer, undercoat layer, and charge generation layer was carried out in the same manner as in Production Example 1 of the photoreceptor.
(Charge transfer layer)
60 parts of the charge transfer material of the structural formula (B-5), a polyester [(P-1) and (M-1) 7: 3 copolymer polyester resin represented by the following structural formula (viscosity average molecular weight 33, 000)] 100 parts, 4-methyl-2,6-di-t-butylphenol 8 parts, and 0.03 part of silicone oil (manufactured by Shin-Etsu Silicone, KF-96) as a leveling agent, 170 parts of dioxane, 400 parts of tetrahydrofuran. It was dissolved in a mixed solvent to prepare a coating solution. This was further dip-coated on an aluminum drum coated with the undercoat layer and the charge generation layer to provide a charge transfer layer so that the film thickness after drying at 125 ° C. for 20 minutes was 20 μm. This is a photoreceptor “PC-A3”.

(Photosensitive member production example-4)
The alumite layer was produced in the same manner as in Production Example 1 for the photoreceptor. A charge generation layer was provided on the alumite layer in the same manner as in Production Example-1 of the photoreceptor without providing an undercoat layer.
(Charge transfer layer) 60 parts of the charge transfer material of the structural formula (B-5) and 100 parts of a polycarbonate resin (m: n = 51: 49, viscosity average molecular weight 31,400) represented by the following structural formula, 4- 8 parts of methyl-2,6-di-t-butylphenol and 0.03 part of silicone oil (manufactured by Shin-Etsu Silicone, KF-96) were dissolved in a mixed solvent of 170 parts of dioxane and 400 parts of tetrahydrofuran to prepare a coating solution. . This was further dip-coated on an aluminum drum coated with the undercoat layer and the charge generation layer to provide a charge transfer layer so that the film thickness after drying at 125 ° C. for 20 minutes was 20 μm. This is a photoreceptor “PC-A4”.

(Photoconductor Production Example-5)
In the same manner as in Production Example 4 of the photoreceptor, a charge generation layer was provided on the alumite layer.
(Charge transfer layer)
35 parts of the charge transfer material of structural formula (A-13), 35 parts of the charge transfer material of (B-2), and polycarbonate resin (Iupilon Z-400, manufactured by Mitsubishi Gas Chemical) represented by the following structural formula Part, 4-methyl-2,6-di-t-butylphenol 8 parts, and 0.03 part of silicone oil (manufactured by Shin-Etsu Silicone, KF-96) as a leveling agent are dissolved in a mixed solvent of 110 parts of toluene and 450 parts of tetrahydrofuran. Thus, a coating solution was prepared. This was further dip-coated on an aluminum drum coated with the undercoat layer and the charge generation layer to provide a charge transfer layer so that the film thickness after drying at 125 ° C. for 20 minutes was 20 μm. This is a photoreceptor “PC-A5”.

(Photoreceptor Production Example-6) (Comparative Photoreceptor: Using β-type TiOPc)
Photoconductor Production Example 4 was prepared in the same manner as in Photoconductor Production Example 4 except that β-type was used instead of Y-type as oxytitanium phthalocyanine. This is a photoreceptor “PC-B1”.

(Photoreceptor Production Example-7) (Comparative Photoreceptor: Use β-type TiOPc)
A photoconductor was produced in the same manner as in Photoconductor Production Example-6 except that in Example 6 of the photoconductor, an aluminum substrate having a diameter of 30 mm and a length of 243 mm was used. This is a photoreceptor “PC-B2”.

Example A1
A cyan toner (TA1) is placed in the developer tank of a color laser printer Color Pagepresto N4-612II manufactured by Casio, and a photoconductor (PC-A1: using Y-type oxytitanium phthalocyanine) is mounted, and an exposure density of 600 dpi is 2. Thin line images were formed in the vertical and horizontal directions of dot on and 2 dots off.

Comparative Example B1
A fine line image was formed in the same manner as in Example A1 except that N4-612II genuine cyan toner (this toner is referred to as toner (TB1); manufactured by a kneading / pulverization method) was used as the toner. The volume average particle diameter (Dv) of TB1 is 9.10 μm, Dv / Dn = 1.24, the 50% circularity is 0.93, and the number ratio of particles having a particle diameter of 0.6 to 2.12 μm is 4.8. %Met.

  The fine line images obtained in Example A1 and Comparative Example B1 were read with a digital microscope manufactured by Keyence, and image analysis was performed with Win Loop software of Mitani Corporation to determine the image density. Note that the value of the image density is raw data calculated by the above-described software by image analysis, and a larger value represents a higher image density. FIG. 3 is a graph showing the image analysis result of the fine line image drawn in the vertical direction, and FIG. 4 is a graph showing the image analysis result of the fine line image drawn in the horizontal direction. In FIG. 3 (vertical direction), the toners of TA1 and TB1 have almost the same peak / valley shape and the resolution is almost the same, but in FIG. 4 (horizontal direction), When TA1 was used, it was found that the shapes of the peaks and valleys were clearly reproduced, indicating high resolution.

Reference Example A laser printer Docprint P1202 manufactured by Xerox, a photoconductor (PC-B2: using β-type oxytitanium phthalocyanine) is mounted, toner TA1 or TB1 is put in a developing tank, an exposure density of 600 dpi, 2 dots on, Thin line images were formed in the vertical and horizontal directions of 2 dots off. Image analysis was performed in the same manner as in Example A1, and FIG. 5 (image analysis result of a fine line image drawn in the vertical direction) and FIG. 6 (image analysis result of a fine line image drawn in the horizontal direction) were obtained. From these results, it can be seen that the same resolution is used in both the vertical direction and the horizontal direction when either toner of TA1 or TB1 is used.

  That is, when a highly sensitive photoreceptor containing Y-type oxytitanium phthalocyanine is used, a high resolution image can be reproduced when the particle size is small and the particle size distribution is sharp. It is shown that the performance of

Comparative Example B1
In Example A1, an image was formed in the same manner as in Example 1 except that N4-612 genuine kneaded / ground cyan toner (TB1) was used instead of the cyan toner (TA1). The volume average particle diameter (Dv) of TB1 is 9.10 μm, Dv / Dn = 1.24, the 50% circularity is 0.93, and the number ratio of particles having a particle diameter of 0.6 to 2.12 μm is 4.8. %Met.

Comparative Example B2
In Comparative Example B1, an image was formed in the same manner as in Example 1 except that N4-612 genuine kneaded / ground yellow toner (TB2) was used instead of the cyan toner (TB1). The volume average particle diameter (Dv) of TB2 is 9.18 μm, Dv / Dn = 1.25, 50% circularity is 0.93, and the ratio of the number of particles having a particle diameter of 0.6 to 2.12 μm is 13.7. %Met.

Comparative Example B3
In Comparative Example B1, an image was formed in the same manner as in Example 1 except that N4-612 genuine kneading / pulverized magenta toner (TB3) was used instead of the cyan toner (TB1). The volume average particle diameter (Dv) of TB3 is 9.16 μm, Dv / Dn = 1.32, the 50% circularity is 0.93, and the number ratio of particles having a particle diameter of 0.6 to 2.12 μm is 15.8. %Met.

Example A2
In Example A1, an image having the same resolution as that of Example A1 is formed by performing image formation in the same manner as Example A1 except that yellow toner (TA2) is used instead of cyan toner (TA1) as the toner. Is obtained.

Example A3
In Example A1, an image having the same resolution as that of Example A1 is formed by performing image formation in the same manner as Example A1 except that magenta toner (TA3) is used as the toner instead of cyan toner (TA1). Is obtained.

Example A5
In Example A1, except that the photoconductor (PC-A2) was used instead of the photoconductor (PC-A1), image formation was performed in the same manner as in Example A1, so that the resolution was the same as that of Example A1. An image is obtained.

Example A6
In Example A1, except that the photoconductor (PC-A3) was used instead of the photoconductor (PC-A1), image formation was performed in the same manner as in Example A1, so that the resolution was the same as that of Example A1. An image is obtained.

Example A7
In Example A1, except that the photoconductor (PC-A4) was used instead of the photoconductor (PC-A1), image formation was performed in the same manner as in Example A1, so that the resolution was the same as that of Example A1. An image is obtained.

Example A8
In Example A1, except that the photoconductor (PC-A5) was used instead of the photoconductor (PC-A1), image formation was performed in the same manner as in Example A1, so that the resolution was the same as that of Example A1. An image is obtained.

DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Charging device 3 Exposure device 4 Developing tank 4k Black developing tank 4y Yellow developing tank 4c Cyan developing tank 4m Magenta developing tank 5 Transfer device 6 Cleaning device 7 Fixing device 42 Agitator 43 Supply roller 44 Developing roller 45 Restriction member 71 Upper part Fixing member 72 Lower fixing member 73 Heating device T Toner P Recording paper

Claims (10)

  In a tandem type image forming apparatus having at least a photoreceptor, a toner and an exposure device, the photoreceptor has at least a photosensitive layer on a conductive support, and the toner is obtained by a wet polymerization method. The volume average particle diameter (Dv) of the toner is 3 to 8 μm, and the relationship between the volume average particle diameter (Dv) and the number average particle diameter (Dn) of the toner is 1.0 ≦ Dv / Dn ≦. A tandem-type image formation characterized in that the number of particles having a particle diameter of 0.6 to 2.12 μm measured by a flow type particle image analyzer is 1.3% or less of the total number of particles. apparatus.   Particles having a volume average particle diameter (Dv) of 3 to 8 μm obtained by a wet polymerization method and a particle diameter of 0.6 to 2.12 μm measured by a flow type particle image analyzer are 3 in the total number of particles. The tandem type image forming apparatus according to claim 1, further comprising: a toner cartridge including a toner of a number% or less; and a photosensitive member having at least a photosensitive layer on a drum-shaped conductive support having an inner diameter of 16 to 30 mm.   Obtained by a wet polymerization method, the volume average particle diameter (Dv) is 3 to 8 μm, and the relationship between the volume average particle diameter (Dv) and the number average particle diameter (Dn) of the toner is 1.0 ≦ Dv / Dn. ≦ 1.3 and a toner having a particle diameter of 0.6 to 2.12 μm measured by a flow type particle image analyzer of 3% or less of the total number of particles, and a drum having an inner diameter of 16 to 30 mm An electrophotographic cartridge provided with a photosensitive member having at least a photosensitive layer on a conductive support.   Particles having a volume average particle diameter (Dv) of 3 to 8 μm obtained by a wet polymerization method and a particle diameter of 0.6 to 2.12 μm measured by a flow type particle image analyzer are 3 in the total number of particles. 2. The tandem image formation according to claim 1, wherein an electrophotographic cartridge including a toner having a number% or less and a drum-shaped conductive support having an inner diameter of 16 to 30 mm and a photosensitive member having at least a photosensitive layer is mounted. apparatus.   5. The tandem image forming apparatus according to claim 1, wherein the photosensitive member is obtained by laminating a charge generation layer and a charge transfer layer in this order on a conductive support.   6. The tandem image forming apparatus according to claim 1, wherein the toner is obtained through a process of aggregating at least polymer primary particles and colorant particles to form particle aggregates.   The tandem-type image forming apparatus according to claim 6, wherein the toner is obtained through a step of attaching resin particles to the particle aggregate.   In an image forming method using at least a photoconductor, an exposure device, and a tandem type image forming apparatus provided with toner, the photoconductor having at least a photoconductive layer on a drum-like conductive support having an inner diameter of 16 to 30 mm, Digital image exposure is performed by an exposure apparatus to form an electrostatic latent image on the photoreceptor, and the electrostatic latent image is developed by a wet polymerization method, and its volume average particle diameter (Dv) is 3 to 8 μm. The relationship between the volume average particle diameter (Dv) and the number average particle diameter (Dn) of the toner is 1.0 ≦ Dv / Dn ≦ 1.3, and is measured by a flow type particle image analyzer. An image forming method comprising using a toner having particles having a particle diameter of 0.6 to 2.12 μm which is 3% by number or less of the total number of particles.   9. The image forming method according to claim 8, wherein the photoconductor is obtained by laminating a charge generation layer and a charge transfer layer in this order on a conductive support. 10. The image forming method according to claim 8, wherein digital image exposure with a recording dot density of 600 dots / inch or more is performed by a photosensitive device.

Images