JP2006330369A - Image forming method and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming method and a process cartridge that prevents image irregularity, decrease in image density and fog image by charging irregularity due to surface contamination of a charging member by a transfer residual toner during forming an image in a low moisture environment. <P>SOLUTION: The image forming method includes steps of bringing a charging member into contact with a photoreceptor to charge, an electrostatic latent image forming step of forming an electrostatic latent image on the photoreceptor, a developing step of developing the latent image with a toner carried by a toner carrier to form a toner image, a transfer step of transferring the toner image formed on an image carrier to a transfer material, and a transfer step of electrostatically fixing the image on the transfer material. The image forming method and the process cartridge are characterized in that: the toner contains a colorant and a binder resin and has an average circularity (C) of 0.930 to 0.995; and the surface layer of the charging member contains composite particles as conductive particles comprising core particles coated with carbon black and having a number average particle diameter Dc (nm) satisfying 5≤Dc≤7,000-(7,000×C). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming method and a process cartridge used in a recording method using an electrophotographic method, an electrostatic recording method, or the like, and more specifically, an electrostatic latent image formed on an electrostatic latent image carrier. The present invention relates to an image forming method and a process cartridge used in a copying machine, a printer, and a fax machine, in which a toner is developed with toner and then transferred onto a transfer material to form an image.

  As a method for charging the photosensitive member, a contact charging method in which a charging member is brought into contact with the photosensitive member for charging is known. For example, while applying a voltage to the conductive roller, the roller is brought into contact with a member to be charged such as a photosensitive member, and the surface of the member to be charged is charged to a predetermined potential. If such contact charging means is used, the voltage can be lowered and the amount of ozone generated can be reduced as compared with the corona discharger.

  As an example of the charging member, there is a charging member that performs charging by pressing a semi-conductive roller, blade, or plate-shaped member having rubber elasticity against the photosensitive member to achieve a uniform contact state with the photosensitive member. For example, a charging member provided with a surface layer is disclosed for the purpose of suppressing contamination of the charging member with toner or the like.

  In addition, as an example of adjusting the resistance of the surface layer of the charging member, it is known that a charging member is prepared by preparing and applying a dispersed rubber, paint, or the like by appropriately containing a conductive agent in a binder resin. A charging member using low-cost carbon black as a conductive agent has been proposed (see Patent Documents 1 to 3).

  Furthermore, by using particles coated with a conductive material as a conductive material, a charging member that can uniformly disperse the conductive particles in the resin and obtain a good image has been proposed (patent) Reference 3).

  On the other hand, many proposals have been made to spheroidize the toner in order to increase the transfer efficiency of the toner, achieve high image quality, and reduce environmental impact by reducing waste toner (see Patent Documents 4 and 5).

However, when using a spheroidized toner, when the transfer residual toner remaining on the photoconductor is cleaned from the photoconductor with a cleaning elastic blade or the like, the spheroidized / spherical toner is slippery and slips through the cleaning elastic blade. The charging member is easily contaminated by the slipped toner, and partial resistance unevenness is formed on the charging member. For this reason, the charging uniformity on the photosensitive member is reduced, and image density unevenness, image density reduction, fog image Such an image defect is likely to occur, and particularly when used in a low-humidity environment, such a problem tends to become prominent.
JP 2004-157720 A JP 2004-4785 A JP 2004-361565 A Japanese Patent Laid-Open No. 2-167666 JP-A-5-61251

  An object of the present invention is to solve the above-described problems. Specifically, image unevenness due to uneven charging on the surface of the charging member due to transfer residual toner during image formation in a low-humidity environment, image density reduction, An image forming method and a process cartridge capable of preventing a fogged image are provided.

In accordance with the present invention, at least a charging member is brought into contact with a photosensitive member having a photosensitive layer and a protective layer on a support which is an image carrier, and charging is performed.
An electrostatic latent image forming step of forming an electrostatic latent image on a charged photoreceptor;
A development step of developing the toner carried on the toner carrier into the electrostatic latent image to form a toner image;
A transfer step of transferring the toner image formed on the image carrier onto a transfer material with or without an intermediate transfer member;
A transfer step for electrostatic transfer to the transfer material;
And the toner has a colorant and a binder resin and the average circularity (C) is 0.930 or more and 0.995 or less.
An image forming method comprising composite particles having a number average particle diameter Dc (nm) in which the core particle A is coated with carbon black as the conductive particles on the surface layer of the charging member and satisfying the range of the following formula: And a process cartridge is provided:
5 ≦ Dc ≦ 7000− (7000 × C)

  As described above, according to the present invention, an image forming method and a process capable of preventing image unevenness due to charging unevenness due to surface contamination of the charging member due to transfer residual toner during image formation in a low humidity environment, image density reduction, and fog image. It became possible to provide a cartridge.

  Next, the image forming method of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of a specific apparatus that can be used to carry out the image forming method of the present invention.

  In FIG. 1, reference numeral 1 denotes a photosensitive drum, and a primary charging roller 6, a developing device 7, and a transfer roller 8 are provided around the photosensitive drum. The electrophotographic photoreceptor 1 is charged by a primary charging roller 6 that contacts the photoreceptor. Then, exposure is performed by irradiating the photosensitive member 1 with exposure light L by a laser generator. The electrostatic latent image on the photoconductor 1 is developed with toner by the developing unit 7 and transferred onto the transfer material 1 by the transfer roller 8 in contact with the photoconductor via the transfer material. The transfer material on which the toner image is placed is conveyed to the fixing device 3 through the conveyance guide and is fixed on the transfer material. Further, a part of the toner remaining on the photosensitive member is removed from the surface of the photosensitive member by the cleaning elastic blade 4 that comes into contact with the photosensitive member of the cleaning device 2 and further contaminated with inorganic part powder adhered to the charging roller. The substance is an image forming method in which the cleaning member 9 removes the substance from the surface of the charging member.

  FIG. 2 shows a specific example of the charging roller 6 shown in FIG. In FIG. 2, 6-1 is a conductive support, 6-2 is an elastic layer provided on the support, and 6-3 is a charging roller having a surface layer formed on the outermost side.

  A feature of the present invention is that the average circularity (C) in which the toner filled in the developing device 7 shown in FIG. 1 has a colorant and a binder resin is 0.930 or more and 0.995 or less. As the conductive particles, the surface layer of the charging member contains composite particles in which the core particle A is coated with carbon black and the number average particle diameter Dc (nm) satisfies the range of 5 ≦ Dc ≦ 7000− (7000 × C). The charging roller is used.

  The toner used in the image forming method must be a toner having at least a binder resin and a colorant and an average circularity (C) of 0.930 or more and 0.995 or less.

  When the average circularity of the toner is 0.930 or more and 0.995 or less, the transfer efficiency is increased, the toner triboelectric charge control is easy, and uniform triboelectric charge can be obtained. A high-quality image can be obtained. In addition, the fact that the specific surface area is small means that the number of moisture adsorption sites is reduced, and the change in the triboelectric charge amount due to moisture adsorption is also suppressed. A more preferable range is toner of 0.960 or more and 0.995 or less.

  If the average circularity value of the toner is less than 0.930, the transfer efficiency is lowered, the specific surface area of the toner is increased, and as a result, the number of moisture adsorption sites is increased, and the change in the triboelectric charge amount is also increased. A toner having an average circularity exceeding 0.995 is difficult to produce, and is out of the scope of the present invention from the viewpoint of productivity.

  The average circularity of the toner is measured using a flow type particle image measuring device “FPIA-2100 type” (manufactured by Sysmex Corporation), and is calculated using the following equation.

  Here, the “particle projected area” is the area of the binarized toner particle image, and the “peripheral length of the particle projected image” is the length of the contour line obtained by connecting the edge points of the toner particle image. Define. The measurement uses the perimeter of the particle image when image processing is performed at an image processing resolution of 512 × 512 (pixels of 0.3 μm × 0.3 μm).

  The circularity in the present invention is an index indicating the degree of unevenness of toner particles, and is 1.000 when the toner particles are completely spherical, and the circularity becomes smaller as the surface shape becomes more complicated.

  The average circularity C, which means the average value of the circularity frequency distribution, is calculated from the following equation, where ci is the circularity (center value) at the dividing point i of the particle size distribution and m is the number of measured particles.

  In addition, “FPIA-2100”, which is a measuring apparatus used in the present invention, calculates the circularity of each particle, and then calculates the average circularity and the circularity standard deviation based on the obtained circularity. The degree 0.4 to 1.0 is divided into classes equally divided every 0.01, and the average circularity and the circularity standard deviation are calculated using the center value of the division points and the number of measured particles.

  As a specific measurement method, 10 ml of ion-exchanged water from which impure solids and the like are previously removed is prepared in a container, and a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant therein, and then further measurement is performed. Add 0.02 g of sample and disperse uniformly. As a means for dispersion, an ultrasonic disperser “Tetora 150 type” (manufactured by Nikka Ki Bios Co., Ltd.) is used, and dispersion treatment is performed for 2 minutes to obtain a dispersion for measurement. In that case, it cools suitably so that the temperature of this dispersion may not be 40 degreeC or more. In order to suppress variation in circularity, the installation environment of the apparatus is controlled at 23 ° C. ± 0.5 ° C. so that the temperature inside the flow type particle image analyzer FPIA-2100 is 26 to 27 ° C. Preferably, autofocus is performed using 2 μm latex particles every 2 hours.

  To measure the circularity of the toner particles, the flow type particle image measuring device is used, and the concentration of the dispersion is readjusted so that the toner particle concentration at the time of measurement is 3000 to 10,000 particles / μl. Measure more than one. After the measurement, using this data, data having an equivalent circle diameter of less than 2 μm is cut to determine the average circularity of the toner particles.

  Furthermore, “FPIA-2100”, which is a measuring apparatus used in the present invention, improves the magnification of the processed particle image as compared with “FPIA-1000” conventionally used for calculating the shape of the toner. Furthermore, the accuracy of toner shape measurement is improved by improving the processing resolution of the captured image (from 256 × 256 to 512 × 512), thereby achieving more reliable capture of fine particles.

  When using the toner having an average circularity (C) of 0.930 or more and 0.995 or less as described above, the surface layer of the charging member is contaminated due to slipping of the transfer residual toner remaining on the photoreceptor from the cleaning step. As a conductive material contained in the surface layer of the charging member, the composite in which the core particle A is coated with carbon black and the number average particle diameter Dc (nm) satisfies 5 ≦ Dc ≦ 7000− (7000 × C). It must be a charging member containing particles (the shaded area surrounded by ■ in FIG. 3).

  By coating the surface of the core particle with carbon black, the carbon black can be present in a layered state on the surface of the composite particle. Therefore, compared with the surface layer dispersed with carbon black itself on the surface layer of the charging member, the slipperiness of the carbon is increased due to the carbon scratching property, and contamination of the surface layer with contaminants such as toner can be reduced.

  Furthermore, by making composite particles, it becomes possible to disperse carbon black in the resin more uniformly than in the surface resin alone, and it should be present uniformly rather than non-uniformly on the surface of the charging member. As a result, it is possible to prevent unevenness due to the deviation between the portion where the composite particles are present and the portion where the composite particles are not present.

  However, as the average circularity of the toner is higher, that is, the closer it is to a spherical shape, the toner itself becomes slippery and slips out from the cleaning process section, and accordingly, contamination of the charging member also increases.

  Therefore, as a result of intensive studies, it was found that the number average particle diameter Dc of the composite particles must be in the range of 5 ≦ Dc ≦ 7000− (7000 × C) as compared with the average circularity C of the toner.

  The clear reason for the above range is unknown, but by analogy, the smaller the number average particle size of the composite particles, the smaller the non-uniformity and bias of the composite particles on the surface layer of the charging member. It is presumed that contamination on the surface of the member may be suppressed.

  Conversely, when the number average particle diameter of the composite particles increases, the unevenness and unevenness of the composite particles on the surface layer of the charging member increases, and therefore, toner contamination is likely to accumulate in a portion where the composite particles do not exist. It is assumed that

  If the number average particle size of the composite particles is less than 5 nm, the particles are too small and easily aggregate, and the dispersion tends to be non-uniform. It is presumed that contamination due to will become easy to accumulate.

  Further, a more preferable range is that Dc of the composite particles is 10 ≦ Dc ≦ 4500− (4500 × C) (portion surrounded by ♦ in the hatched portion in FIG. 3).

  In addition, the composite particles contained in the surface layer are preferably 10 parts by mass or more and 120 parts by mass or less with respect to 100 parts by mass of the binder resin used for the surface layer. If it exceeds 120 parts by mass, the film strength of the surface layer will be reduced, and the film will be peeled off due to durability, and damage will easily occur, and if it is less than 10 parts by mass, the effect of reducing contamination by composite particles will be difficult to be exhibited.

  As the core particle A in the present invention, various particles such as resin particles, metal particles, metal oxide particles and the like can be used. More preferably, the metal oxide particles a are used from the viewpoint of carbon black coverage and particle dispersibility. Examples thereof include silica, alumina, titanium oxide, zinc oxide, magnesium oxide, iron oxide, strontium titanate, calcium titanate, magnesium titanate, barium titanate and calcium zirconate, among which silica fine particles are preferable. .

  Further, the core particle A is preferably surface-treated. By applying the surface treatment, the core particles and carbon black can be more firmly attached, and when the composite particles are dispersed in the resin, the separation of the carbon black can be prevented, and when dispersed in the surface layer Since the effect as a composite particle is exhibited by this, it is preferable.

  As the surface treatment agent, alkoxysilane, fluoroalkylsilane, polysiloxane and other organic silicon compounds, silane-based, titanate-based, aluminate-based and zirconate-based coupling agents, one or more of oligomers or polymer compounds Can be used. More preferred is an organosilicon compound.

  As the organosilicon compound in the present invention, alkoxysilane, an organosilane compound generated from alkoxysilane, polysiloxane, modified polysiloxane, terminal-modified polysiloxane, fluoroalkylsilane, or a mixture thereof can be used.

  Specific examples of the alkoxysilane include methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, dimethyldimethoxysilane, methyltrimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, isobutyltrimethoxysilane. Examples include methoxysilane and decyltrimethoxysilane.

  The coating amount of the surface treatment agent is preferably 0.01 to 15.0% by mass with respect to the core particles A. If it is less than 0.01% by mass, it may be difficult to adhere carbon black to the core particles A. When it exceeds 15.0 mass%, core particles will aggregate with a processing agent and will obstruct | occlude the coating | cover of carbon black.

  The surface treatment method for the core particles A in the present invention is performed by mechanically mixing and stirring the core particles A and the surface treatment agent or a solution of the surface treatment agent (ball mill, sand mill, paint shaker, dyno mill, pearl mill, and the like. Dispersion means, etc.) or mechanically mixed and stirred while spraying the surface treatment agent or the solution of the surface treatment agent onto the core particles A. Furthermore, you may further grind | pulverize the particle | grains after surface treatment as needed.

  As the carbon black coated on the core particle A, furnace black, ketjen black, channel black or the like is preferably used. More specifically, granular acetylene black manufactured by Electrochemical Co., Ltd., “HS-500” manufactured by Asahi Carbon Co., Ltd., “Asahi Thermal FT”, “Asahi Thermal MT”, “Ketjen Black” manufactured by Lion Aguso Co., Ltd. , Vulcan XC-72 manufactured by Cabot Corporation, “REGAL 400R”, “MONARCH 1300” from Cabot Corporation, “Color Black FW200” from Degussa, “SPECIAL BLACK 4”, “PRINTEX 150T”, “PRINTEX 140T”, “PRINTX” And “MA100” manufactured by Mitsubishi Chemical Corporation. These may be used alone or in combination of two or more.

  As a method of coating the core particle A with carbon black, the core particle A and carbon black, and the surface-treated core particle A and carbon black are mixed and stirred. In particular, a device capable of simultaneously performing shearing, spatula and compression, for example, a wheel-type kneader, a ball-type kneader, a blade-type kneader or a roll-type kneader can be used. A wheel kneader can be used more effectively. And if necessary, after mixing and stirring, further drying and heat treatment may be performed.

  In addition, the coating layer does not necessarily need to completely cover the core particles, and the core particles may be exposed as long as the effects of the present invention are obtained. That is, the coating layer may be formed discontinuously.

  Furthermore, the surface layer preferably contains metal oxide particles b having a relative dielectric constant of 50 or more and 300 or less. If the relative dielectric constant is less than 50, the effect on the charging ghost hardly appears, and if it exceeds 300, abnormal discharge due to excessive charging tends to occur.

  By containing particles having a high dielectric constant, the dielectric constant of the charging member is increased, and charging defects called charging ghosts affected by the potential of the photoreceptor one round before can be reduced.

The relative dielectric constant resistance of the particles was measured by a tablet method. That is, a powder sample is put in a cylinder with a bottom area of 2.26 cm ² and 15 kg is applied to the upper and lower electrodes, and simultaneously, a voltage of 1 Vpp and 1 MHz is applied to measure an alternating current, and then normalized to obtain a relative dielectric constant. Calculated.

As the particles having a relative dielectric constant of 50 or more and 300 or less, the general formula MO · TiO ₂ (wherein M is one selected from the group consisting of Ba, Sr, Ca, Mg, Co, Pb, Zn, Be and Cd or (For example, barium titanate, calcium titanate, magnesium titanate, strontium titanate, barium strontium titanate, and barium calcium titanate) represented by Rutile-type titanium oxide particles are preferably used because they have a high dielectric constant and are easily available.

  About the average particle diameter of the composite particle | grains and metal oxide fine particle a and b in this invention, 100 particle diameters are measured from the photograph image | photographed with the magnification of 50,000 times with the electron microscope, and the average can be calculated | required.

  In addition, as a method for controlling the surface shape, the surface layer may contain a roughening material such as resin particles having a number average particle diameter of about 0.5 μm to 25 μm as long as the effect of the present invention is not lost. It doesn't matter.

  The resin particles as the roughening material include polyamide resin, silicone resin, fluororesin, (meth) acrylic resin, styrene resin, phenol resin, polyester resin, melamine resin, urethane resin, olefin resin, epoxy resin and their co-polymers. Resin particles such as coalesced and modified products, derivatives, ethylene-propylene-diene copolymer (EPDM), styrene-butadiene copolymer rubber (SBR), silicone rubber, urethane rubber, isoprene rubber (IR), butyl rubber, acrylonitrile Rubber fine particles such as butadiene copolymer rubber (NBR), chloroprene rubber (CR), epichlorohydrin rubber, polyolefin thermoplastic elastomer, urethane thermoplastic elastomer, polystyrene thermoplastic elastomer, fluororubber thermoplastic elastomer Examples include thermoplastic elastomer fine particles such as polyester thermoplastic elastomers, polyamide thermoplastic elastomers, polybutadiene thermoplastic elastomers, ethylene vinyl acetate thermoplastic elastomers, polyvinyl chloride thermoplastic elastomers, and chlorinated polyethylene thermoplastic elastomers. .

  In addition, barium sulfate, molybdenum disulfide, calcium carbonate, magnesium carbonate, dolomite, talc, kaolin clay, mica, aluminum hydroxide, magnesium hydroxide, zeolite, wollastonite, diatomaceous earth, glass beads, bentonite, Mention may be made of particles such as montmorillonite, asbestos, hollow glass spheres, graphite, rice husks, organometallic compounds and organometallic salts.

  Examples of the material used for the surface layer include conventionally known layers such as a layer using an elastomer such as resin, rubber, and thermoplastic elastomer as a binder material.

  Examples of the resin include fluorine resin, polyamide resin, acrylic resin, polyurethane resin, silicone resin, butyral resin, styrene-ethylene-butylene-olefin copolymer (SEBC), and olefin-ethylene-butylene-olefin copolymer (CEBC). Is mentioned.

  Examples of rubber include natural rubber (which may be vulcanized) and synthetic rubber. Examples of synthetic rubber include ethylene-propylene-diene copolymer (EPDM), styrene-butadiene copolymer rubber (SBR), Examples include silicone rubber, urethane rubber, isoprene rubber (IR), butyl rubber, acrylonitrile-butadiene copolymer rubber (NBR), chloroprene rubber (CR), acrylic rubber, and epichlorohydrin rubber.

  As thermoplastic elastomers, polyolefin-based thermoplastic elastomers, urethane-based thermoplastic elastomers, polystyrene-based thermoplastic elastomers, fluororubber-based thermoplastic elastomers, polyester-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, polybutadiene-based thermoplastic elastomers, ethylene Examples thereof include a vinyl acetate thermoplastic elastomer, a polyvinyl chloride thermoplastic elastomer, and a chlorinated polyethylene thermoplastic elastomer.

  These may be used alone or in combination of two or more as a mixture or copolymer.

  As a support for the charging member, it is only necessary to have conductivity (conductive support). For example, a support made of metal (made of alloy) such as iron, copper, stainless steel, aluminum and nickel is used. it can. In addition, for the purpose of imparting scratch resistance to these surfaces, plating treatment or the like may be performed as long as the conductivity is not impaired.

  The method for producing the toner used in the present invention is not particularly limited, and a suspension polymerization method, an emulsion polymerization method, an association polymerization method, a kneading pulverization method, or the like is used.

  A method for producing toner in the kneading and pulverizing method will be described below.

  The binder resin used in the pulverized toner used in the present invention includes polystyrene, poly-α-methylstyrene, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-acetic acid. A vinyl copolymer, a styrene-acrylic acid ester copolymer, a styrene-methacrylic acid acrylic copolymer, a vinyl chloride resin, a polyester resin, an epoxy resin, a phenol resin, a polyurethane resin, etc. can be used alone or in combination. Styrene-acrylic, styrene-methacrylic copolymer resin, and polyester resin are preferable, and a hybrid having a polyester unit and a vinyl polymer unit, in which at least a condensation polymerization resin such as a polyester resin and a vinyl resin are partially reacted. It is possible to use a resin component Sex and fixability, particularly preferred in the storage stability. In this hybrid resin, two types of resins that are inherently poor in compatibility are uniformly dispersed, so that the characteristics of both resins can be utilized.

  Further, when the toner used in the present invention is controlled to be positively charged, a modified product by a fatty acid metal salt or the like; 4 such as tributylbenzidylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate or the like. Onium salts such as quaternary ammonium salts and their analogs such as phosphonium salts; amines and polyamine compounds; metal salts of higher fatty acids; acetylacetone metal complexes; diorganotin oxides such as dibutyltin oxide, dioctyltin oxide, and dicyclohexyltin oxide Diorgano tin borate such as dibutyl tin borate, dioctyl tin borate and dicyclohexyl tin borate is added. Moreover, when controlling to negative charging property, an organometallic complex and a chelate compound are effective, and a monoazo metal complex, an acetylacetone metal complex, an aromatic hydroxycarboxylic acid, and an aromatic dicarboxylic acid type metal complex can be used. The amount used is preferably 0.1 to 15 parts by mass, more preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the binder resin.

  A release agent can be added to the pulverized toner used in the present invention, if necessary. For example, aliphatic hydrocarbon waxes such as low molecular weight polyethylene, low molecular weight polypropylene, paraffin wax, Fischer-Tropsch wax or oxides thereof; waxes mainly composed of aliphatic esters such as carnauba wax, montanic ester wax, or the like What deoxidized one part or all part is mentioned. In addition, saturated linear fatty acids such as palmitic acid, stearic acid, and montanic acid; unsaturated fatty acids such as brassic acid, eleostearic acid, and valinalic acid; stearyl alcohol, aralkyl alcohol, behenyl alcohol, carnauvir alcohol, and seryl alcohol , Saturated alcohols such as merisyl alcohol; polyhydric alcohols such as sorbitol; fatty acid amides such as linoleic acid amide; saturated fatty acid bisamides such as methylenebisstearic acid amide; unsaturated fatty acid amides such as ethylene bisoleic acid amide Aromatic bisamides such as N, N′-distearylisophthalic acid amide; fatty acid metal salts such as zinc stearate; waxes grafted to aliphatic hydrocarbon waxes using vinyl monomers such as styrene; Monoglyce behenate Fatty acids with polyhydric alcohols partial esters of de like; methyl esterified products having a hydroxyl group obtained by hydrogenation such as vegetable oils may also be used. The addition amount is preferably 0.1 to 20 parts by mass, particularly 0.5 to 10 parts by mass with respect to 100 parts by mass of the binder resin.

  When the magnetic material is used as the colorant in the toner used in the present invention, the magnetic toner can be constituted as it is. Examples of magnetic materials used in the present invention include iron oxides such as magnetite, maghemite, and ferrite, and iron oxides including other metal oxides; metals such as Fe, Co, and Ni, or these metals and Al, Cu, Examples include alloys with metals such as Pb, Mg, Sn, Zn, Sb, Be, Bi, Cd, Ca, Mn, Se, Ti, W, and V, and mixtures thereof.

Specifically, as the magnetic material, triiron tetroxide (Fe ₃ O ₄ ), iron sesquioxide (γ-Fe ₂ O ₃ ), zinc iron oxide (ZnFe ₂ O ₄ ), iron yttrium oxide (Y ₃ Fe) ₅ O ₁₂ ), iron cadmium oxide (CdFe ₂ O ₄ ), iron gadolinium oxide (Gd ₃ Fe ₅ O ₁₂ ), iron oxide copper (CuFe ₂ O ₄ ), iron oxide lead (PbFe ₁₂ O ₁₉ ), nickel iron oxide (NiFe ₂ O ₄ ), iron oxide neodymium (NdFe ₂ O ₃ ), barium oxide (BaFe ₁₂ O ₁₉ ), magnesium iron oxide (MgFe ₂ O ₄ ), iron manganese oxide (MnFe ₂ O ₄ ), iron lanthanum oxide (LaFeO ₃ ), iron powder (Fe), cobalt powder (Co), nickel powder (Ni) and the like. The above-described magnetic materials are used alone or in combination of two or more. A particularly suitable magnetic substance is a fine powder of triiron tetroxide or γ-iron sesquioxide.

These ferromagnets have an average particle size of 0.05 to 1.00 μm, magnetic properties of 795.8 kA / m applied, coercive force (Hc) of 1.6 to 12.0 kA / m, and saturation magnetization (σs). Those having 50 to ²⁰⁰ Am ² / kg and residual magnetization (σr) of ^{2 to} 20 Am ² / kg are preferable. The saturation magnetization is more preferably 50 to 100 Am ² / kg.

  Moreover, it is preferable that the shape of magnetic iron oxide is an octahedron. This is because the magnetic iron oxide particles having such a shape are easily separated from each other, have little cohesiveness, and can be uniformly dispersed in the binder resin. In addition, such magnetic iron oxide particles have irregularities on the particle surface, have many surfaces and ridges, and have an appropriate angle. Since it is also fixed on the top, it can be prevented from falling off the magnetic toner particles.

  Further, the magnetic material is preferably used in an amount of 65 to 200 parts by mass, more preferably 70 to 150 parts by mass with respect to 100 parts by mass of the binder resin.

  Further, as the colorant, carbon black, titanium white, and any other pigments and / or dyes may be further used. For example, when the toner used in the present invention is used as a color toner, examples of the dye include C.I. I. Direct Red 1, 4, C.I. I. Acid Red 1, C.I. I. Basic Red 1, C.I. I. Modern Tread 30, C.I. I. Direct Blue 1, 2, C.I. I. Acid Blue 9, 15, C.I. I. Basic Blue 3, 5, C.I. I. Modern Blue 7, C.I. I. Direct Green 6 and C.I. I. Basic green 4, 6, etc. are mentioned. As pigments, yellow lead, cadmium yellow, mineral fast yellow, navel yellow, naphthol yellow S, Hansa yellow G, permanent yellow NCG, tartra gin lake, red mouth yellow lead, molybdenum orange, permanent orange GTR, pyrazolone orange, benzidine orange G , Cadmium Red, Permanent Red 4R, Watching Red Calcium Salt, Eosin Lake, Brilliant Carmine 3B, Manganese Purple, Fast Violet B, Methyl Violet Lake, Bitumen, Cobalt Blue, Alkaline Blue Lake, Victoria Blue Lake, Phthalocyanine Blue, Fast Sky Blue , Indanthrene Blue BC, Chrome Green, Chrome Oxide, Pigment Green B, Malachite Green Lake and Final Yellow Green G, and the like.

  Next, after fully mixing the binder resin, release agent, colorant, and other additives as necessary with a mixer such as a Henschel mixer or a ball mill, such as a heating roll, a kneader, and an extruder After being melt-mixed using a thermal kneader, the obtained kneaded product is cooled, coarsely pulverized by pulverizing means, and finely pulverized / classified by appropriate pulverizing / classifying means to produce toner particles. .

  As the pulverizing apparatus, the pulverizing apparatus as described above can be used. However, when an airflow pulverizer such as a jet mill is used, it is difficult to obtain a toner having a desired circularity. It is necessary to perform soft pulverization by lowering the pulverization pressure or to further add a surface modification treatment step after pulverization. From the viewpoint of improving toner production efficiency, a mechanical pulverizer is used as a pulverizing means. More preferably, it is used.

  Examples of mechanical pulverizers include pulverizer inomizer manufactured by Hosokawa Micron Co., Ltd., pulverizer KTM manufactured by Kawasaki Heavy Industries, Ltd., and turbo mill manufactured by Turbo Industry Co., Ltd. Are preferably used.

  Further, a spheronization treatment may be performed after pulverization. For example, devices such as the Mechano-Fusion System manufactured by Hosokawa Micron Co., Ltd. and the Hybridization System manufactured by Nara Machinery Co., Ltd., press the toner against the inside of the casing by centrifugal force with high-speed rotating blades. There is a method of applying a mechanical impact force to the toner.

  Next, a method for producing the toner used in the present invention in the suspension polymerization method will be described.

  A toner having a higher degree of circularity can be obtained by a production method using a polymerization method. First, a low softening point substance, a polar resin, a colorant, a charge control agent, a polymerization initiator, and other additives were added to the polymerizable monomer and dissolved or dispersed uniformly by a homogenizer or an ultrasonic disperser. The monomer system is dispersed in an aqueous phase containing a dispersion stabilizer by a normal stirrer, a homogenizer, a homomixer or the like. At this time, granulation is preferably performed while adjusting the stirring speed and time so that the monomer droplets have a desired developer particle size. Thereafter, stirring may be performed to such an extent that the particle state is maintained by the action of the dispersion stabilizer and the sedimentation of the particles is prevented. The polymerization temperature is preferably set to 40 ° C. or higher, generally 50 ° C. to 90 ° C. Further, the temperature may be raised in the latter half of the polymerization reaction, and further, in order to remove unreacted polymerizable monomers and by-products that cause odors when fixing the developer, the latter half of the reaction or at the end of the reaction. A part of the aqueous medium may be distilled off. After completion of the reaction, the produced developer particles are washed, collected by filtration and dried. In the suspension polymerization method, it is usually preferable to use 300 parts by mass to 3000 parts by mass of water as a dispersion medium with respect to 100 parts by mass of the monomer system.

  Toner particle size distribution control and particle size control can be done by adjusting the pH of the system during granulation, changing the type and addition amount of a sparingly water-soluble inorganic salt and protective colloid, mechanical equipment conditions, For example, it can be performed by controlling the stirring speed such as the peripheral speed of the rotor, the number of passes, the shape of the stirring blade, the shape of the container, or the solid content concentration in the aqueous solution.

  Examples of the polymerizable monomer used in the present invention include styrene monomers such as styrene, o- (m-, p-) methylstyrene, m- (p-) ethylenestyrene; methyl (meth) acrylate, Propyl (meth) acrylate, butyl (meth) acrylate, octyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, behenyl (meth) acrylate, 2-ethylhexyl (meth) acrylate (Meth) acrylic acid ester monomers such as dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate; monomers such as butadiene, isoprene, cyclohexane, (meth) acrylonitrile and acrylic amide Preferably used.

  Moreover, as a polar resin added at the time of superposition | polymerization, the copolymer of a styrene (meth) acrylic acid, a maleic acid copolymer, a polyester resin, or an epoxy resin is used preferably.

  Further, as the low softening point substance used in the present invention, paraffin wax, polyolefin wax, Fischer-Tropsch wax, amide wax, higher fatty acid, ester wax and derivatives thereof, or graft / block compounds thereof are preferably used. It is done.

  As the charge control agent used in the present invention, known ones can be used, but a charge control agent having no polymerization inhibition and no solubilized product in an aqueous system is particularly preferable. Specific examples of negative compounds include salicylic acid, naphthoic acid, dicarboxylic acid, metal compounds of derivatives thereof, polymer compounds having sulfonic acid in the side chain, boron compounds, urea compounds, silicon compounds, calixarene, etc. As the positive system, a quaternary ammonium salt, a polymer compound having the quaternary ammonium salt in the side chain, a guanidine compound, an imidazole compound, or the like is preferably used. The charge control agent is preferably 0.2 to 10 parts by mass with respect to 100 parts by mass of the polymerizable monomer.

  Examples of the polymerization initiator used in the present invention include 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexane-1). -Carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azo-based polymerization initiators such as azobisisobutylnitrile, benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroxy peroxide Peroxide polymerization initiators such as 2,4-dichlorobenzoyl peroxide and lauroyl peroxide are used.

  The amount of the polymerization initiator to be added varies depending on the target degree of polymerization, but is generally 0.5 to 20% by mass added to the monomer. The kind of the polymerization initiator is slightly different depending on the polymerization method, but may be used alone or mixed with reference to the 10-hour half-life temperature.

  Examples of the dispersant used when using suspension polymerization include inorganic calcium oxides such as tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, and hydroxide. Examples thereof include magnesium, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate, bentonite, silica, alumina, a magnetic substance, and ferrite. Examples of the organic compound include polyvinyl alcohol, gelatin, methylcellulose, methylhydroxypropylcellulose, ethylcellulose, sodium salt of carboxymethylcellulose, starch and the like, and these are used by being dispersed in an aqueous phase. These dispersants are preferably used in an amount of 0.2 to 2.0 parts by mass with respect to 100 parts by mass of the polymerizable monomer.

  These commercially available dispersants may be used as they are, but in order to obtain dispersed particles having a fine and uniform particle size, they can also be obtained by producing the inorganic compound in a dispersion medium under high-speed stirring. . For example, in the case of calcium phosphate, a dispersant preferable for the suspension polymerization method can be obtained by mixing an aqueous sodium phosphate solution and an aqueous calcium chloride solution under high-speed stirring.

  Moreover, you may use 0.001-0.1 mass part surfactant together for refinement | miniaturization of these dispersing agents. Specifically, commercially available nonionic, anionic and cationic surfactants can be used, such as sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, potassium stearate. Or calcium oleate etc. are used preferably.

  Further, the same colorant and magnetic material as those used for the pulverized toner may be used.

  In order to improve the fluidity of the toner and to improve the transfer efficiency as necessary, the inorganic particles or the fine organic particles are used to prevent the toner from slipping out from the cleaning process section. Is preferably added to the toner particles.

Examples of such fine powders include fluorine resin powders such as vinylidene fluoride fine powder and polytetrafluoroethylene fine powder; fine powder silica such as wet process silica and dry process silica, fine powder titanium oxide (titania), fine powder. Powdered alumina, hydrotalcite compounds (eg, layered compound represented by Mg _0.72 Al _0.28 (OH) ₂ (CO ₃ ) _0.14 · 0.54H ₂ O), strontium titanate, barium titanate Examples thereof include inorganic fine powders of perovskite crystals, treated silica whose surfaces have been subjected to a hydrophobic treatment with a silane coupling agent, a titanium coupling agent, silicone oil, etc., treated titanium oxide, treated alumina, and the like.

  Among the above-mentioned fine powders, the inorganic fine powders of perovskite type crystals are effective in suppressing toner slip-through. Therefore, it is preferable to add them to the toner particles because it leads to a reduction in contamination of the charging member.

  In particular, it is preferable that an inorganic fine powder having an average particle diameter of 300 nm or more and 3000 nm or less of the inorganic fine powder of the perovskite crystal is added. If the particle size is less than 300 nm, the inorganic fine powder itself slips out of the cleaning process part, and the charging member is likely to be contaminated. On the other hand, if it exceeds 3000 nm, scratches on the photoreceptor and blades are likely to occur.

  A scanning electron microscope (SEM) was used for the shape and particle size of the inorganic fine powder. Specifically, using a FE-SEM manufactured by Hitachi, the fine particles on the toner magnified 50,000 times were randomly sampled, and the arithmetic average value of the major axis diameter and the minor axis diameter was obtained. The average particle size was taken. The same operation was performed over 100 fine particles, and the number average particle size of the fine particles was obtained by arithmetic averaging.

  The addition amount of the perovskite crystal inorganic fine powder is preferably 0.1 parts by mass or more and 5.0 parts by mass or less with respect to 100 parts by mass of the toner particles. If the amount is less than 0.1 parts by mass, it is difficult for the toner to pass through, and if the amount exceeds 5.0 parts by mass, the inorganic fine powder itself slips through the cleaning process part and easily contaminates the charging member.

  As an addition method, the toner can be obtained by sufficiently mixing the fine powder and the toner particles with a mixer such as a Henschel mixer.

  Examples of the present invention are specifically shown below, but are not limited thereto.

  First, an example of the toner and charging roller used in the image forming method of the present invention will be described. In addition, "part" in an Example represents a mass part.

(Example of binder resin production for toner)
-610 parts of terephthalic acid-610 parts of trimellitic anhydride-310 parts of fumaric acid-1050 parts of propoxylated bisphenol A-450 parts of ethoxylated bisphenol A 4 parts of the above polyester monomer together with 189 parts of hydrocarbon wax and esterification catalyst The flask was charged with a decompression device, a water separation device, a nitrogen gas introduction device, a temperature measurement device, and a stirring device and stirred at a temperature of 130 ° C. in a nitrogen atmosphere, while the vinyl polymer monomer (621 parts of styrene, A mixture of 136 parts of 2-ethylhexyl acrylate and 0.13 part of divinylbenzene was added dropwise from a dropping funnel over 4 hours. The mixture was aged for 3 hours while maintaining the temperature at 130 ° C., and the reaction was performed by raising the temperature to 230 ° C. After completion of the reaction, it was taken out from the container, cooled and pulverized to obtain a resin A.

(Toner particle production example 1)
-Resin A 100 parts-Magnetic substance 100 parts-Salicylic acid metal compound 2 parts-Hydrocarbon wax 7 parts The above is mixed using a Henschel mixer, melt-kneaded with a twin-screw extruder kneader, and then coarsely pulverized with a hammer mill The coarsely pulverized product was finely pulverized with a turbo mill type T-250, and the resulting fine powder was classified with an air classifier to obtain toner particles 1.

(Toner particle production example 2)
Toner particles 1 were put into a hybridization system apparatus manufactured by Nara Machinery Co., Ltd. and subjected to spheronization to obtain toner particles 2.

(Toner particle production example 3)
The toner particles 3 having different average circularity were obtained by adjusting the spheroidizing treatment by introducing into the hybridization system apparatus of Toner Particle Production Example 2.

(Toner particle production example 4)
Into 709 g of ion-exchanged water, 451 parts of a 0.1 M Na ₃ PO ₄ aqueous solution was added and heated to 60 ° C., and then 67.7 parts of a 1.0 M CaCl ₂ aqueous solution was gradually added, and Ca ₃ (PO _{4 2} ) An aqueous medium containing ₂ was obtained.

next,
・ Styrene 80 parts ・ butyl acrylate 20 parts ・ unsaturated polyester resin 2 parts ・ saturated polyester resin 3 parts ・ negative charge control agent (monoazo dye-based Fe compound) 1.2 parts ・ surface-treated hydrophobized magnetic material 100 parts The prescription was uniformly dispersed and mixed using an attritor (Mitsui Miike Chemical Co., Ltd.).

  This monomer composition was heated to 60 ° C., and 6 parts of ester wax (the maximum value of endothermic peak in DSC, 72 ° C.) mainly composed of behenyl behenate was added, mixed and dissolved therein, and polymerization initiator 2 was added thereto. , 2′-azobis (2,4-dimethylvaleronitrile) [t1 / 2 = 140 minutes, 60 ° C.] 5 parts were dissolved.

The polymerizable monomer system was charged into the aqueous medium and granulated by stirring at 10,000 rpm for 15 minutes in a TK homomixer (Special Machine Industries Co., Ltd.) at 60 ° C. in an N ₂ atmosphere. . Thereafter, the mixture was reacted at 60 ° C. for 6 hours while stirring with a paddle stirring blade. Thereafter, the liquid temperature was raised to 80 ° C., and stirring was further continued for 4 hours. After completion of the reaction, distillation was further performed at 80 ° C. for 2 hours, after which the suspension was cooled, hydrochloric acid was added to dissolve Ca ₃ (PO ₄ ) ₂ , filtered, washed with water, and dried to obtain toner particles 4. .

(Toner particle production example 5)
450 parts of 0.1M-Na ₃ PO ₄ aqueous solution was added to 710 parts of ion-exchanged water in a 2 liter four-necked flask, heated to 60 ° C., and then a high-speed stirring apparatus TK homomixer (specialized machine). The product was stirred at 12000 rpm. To this, 68 parts of 1.0 M CaCl ₂ aqueous solution was gradually added to obtain an aqueous dispersion medium containing a minute hardly water-soluble dispersion stabilizer.

On the other hand, as dispersoid (monomer) 160 parts of styrene
40 parts of n-butyl acrylate (colorant) C.I. I. Pigment Red 202 10 parts (charge control agent) 2,5-di-tert-butylsalicylic acid Al compound 4 parts (release agent) Ester wax (softening point 75 ° C.) 10 parts (others) Saturated polyester resin 10 parts Among them, the colorant, the aluminum compound of 2,5-di-tert-butylsalicylic acid, and styrene alone were premixed using Ebara Milder (manufactured by Ebara Seisakusho). Next, all the above formulations were heated to 60 ° C., dissolved and dispersed to obtain a monomer mixture. Further, while maintaining at 60 ° C., 10 parts of initiator 2,2′-azobis (2,4-dimethylvaleronitrile) was added and dissolved to prepare a monomer composition.

  The monomer composition was charged into a dispersion medium prepared in a 2 liter flask of the homomixer. Using a TK homomixer at 60 ° C. in a nitrogen atmosphere, the mixture was stirred at 10,000 rpm for 20 minutes to granulate the monomer composition. Thereafter, the mixture was reacted at 60 ° C. for 6 hours while stirring with a paddle stirring blade, and then polymerized at 80 ° C. for 10 hours.

After completion of the polymerization reaction, the reaction product was cooled, hydrochloric acid was added to dissolve Ca ₃ (PO ₄ ) ₂ , filtered, washed with water, and dried to obtain toner particles 5.

(Toner particle production example 6)
Styrene acrylic resin 100 parts (styrene-butyl acrylate copolymer ratio = 78: 22)
・ Magnetic material 100 parts ・ Salicylate metal compound 4 parts ・ Hydrocarbon wax 2 parts The above is mixed using a Henschel mixer, melt-kneaded with a twin-screw extruder kneader, coarsely pulverized with a hammer mill, and jet mill Finely pulverized toner particles 6 were obtained.

(Fluidity improver Si)
Hydrophobic silica (BET = 130 m ² / g) fine particle silica whose surface was treated with 20 parts of dimethyl silicone oil was prepared on 100 parts of silica having a primary particle size of about 9 nm.

(Production Example 1 of Perovskite Type Inorganic Fine Powder)
1500 parts of strontium carbonate and 800 parts of titanium oxide were wet mixed in a ball mill for 8 hours, then filtered and dried, and the mixture was molded at a pressure of 5 kg / cm ² and calcined at 1300 ° C. for 8 hours. This was mechanically pulverized to obtain an inorganic fine powder (B-1) having a weight average diameter of 400 nm and strontium titanate (SrTiO ₃ ).

(Production Example 2 of Inorganic Fine Powder B)
Grinding conditions were adjusted to obtain strontium titanate B-2 (250 nm), B-3 (2500 nm), B-4 (3300 nm) and B-5 (1500 nm) having different particle diameters.

  Next, toner particles, fluidity improver Si, and perovskite type inorganic fine powder as shown in Table 1 below are weighed in parts and externally added using a Henschel mixer FM10B to produce toners 1-15. did. Table 1 below shows the circularity and toner average particle diameter of toners 1-15.

  The average particle diameter of the toner can be measured by various methods. In the present invention, the average particle diameter of the toner was measured using a Coulter counter multisizer.

  Connected to Coulter Counter Multisizer II (manufactured by Coulter Co.) is an interface that outputs number distribution and volume distribution (manufactured by Nikka) and CX-1 personal computer (manufactured by Canon). Prepare a 1% NaCl aqueous solution with sodium. As a measuring method, 0.1 to 5 ml of a surfactant (preferably alkylbenzene sulfonate) is added as a dispersant to 100 to 150 ml of the aqueous electrolytic solution, and 2 to 20 mg of a measurement sample is further added. The electrolyte in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and when measuring the toner particle size with the Coulter Counter Multisizer II type, a 100 μm aperture is used. The volume average particle size was calculated by measuring the volume of the toner.

(Composite Particle Production Example 1)
To 7.0 kg of silica fine particles (average particle size 20 nm), 140 g of methyl hydrogen polysiloxane is added to the silica fine particles while operating the edge runner, and mixed and stirred for 30 minutes with a linear load of 588 N / cm (60 Kg / cm). Then, the surface of the silica fine particles was treated with methyl hydrogen polysiloxane. The stirring speed at this time was 22 rpm.

  Next, 7.0 kg of carbon black particles (particle diameter: 15 nm) were added over 10 minutes while the edge runner was operated, and further mixed and stirred for 90 minutes with a linear load of 588 N / cm (60 Kg / cm). Carbon black was adhered to the surface of the hydrogen polysiloxane-coated silica particles, and then dried at 80 ° C. for 45 minutes using a dryer to obtain composite particles. The stirring speed at this time was 22 rpm. The obtained composite particles B-1 had an average particle size of 18 nm. Table 2 shows the characteristics.

(Composite Particle Preparation Examples B-2 to B-8)
Composite particles B-2 to B-8 were obtained in the same manner as the composite particle B-1, except that the particle size of the silica fine particles was changed and the average particle size of the composite particles was changed as shown in Table 2 below. . Table 2 shows the characteristics.

(Composite particle production example B-9)
To 7.0 kg of silica fine particles (average particle diameter 20 nm), 7.0 kg of carbon black particles (particle diameter 15 nm) was added over 10 minutes while operating the edge runner, and a line of 588 N / cm (60 Kg / cm) was added. After mixing and stirring with a load for 60 minutes to deposit carbon black on the surface of the silica fine particles, drying was performed at 80 ° C. for 45 minutes using a dryer to obtain composite particles. The stirring speed at this time was 22 rpm. The obtained composite particles B-9 had an average particle size of 20 nm. Table 2 shows the characteristics.

(Composite Particle Production Example B-10)
7.0 kg of carbon black particles (particle size 15 nm) are added to 14.0 kg of anatase-type titanium oxide fine particles (average particle size 25 nm) over 10 minutes while operating the edge runner, and further 588 N / cm (60 Kg / cm). The mixture was stirred for 60 minutes with a linear load of), and carbon black was adhered to the titanium oxide fine particles, followed by drying at 80 ° C. for 45 minutes using a dryer to obtain composite particles. The stirring speed at this time was 22 rpm. The obtained composite particles B-10 had an average particle size of 25 nm. Table 2 shows the characteristics.

(Example of production of elastic layer of charging member)
A stainless steel core bar having a total length of 345 mm, with a 9 mm length at both end portions and a diameter of 6 mm, and an elastic layer covering portion of 9 mm was used as a support (conductive support). A thermosetting conductive adhesive was applied to this and dried.

  Next, 100 parts of epichlorohydrin rubber terpolymer, 55 parts of calcium carbonate, 8 parts of aliphatic polyester plasticizer, 1 part of zinc stearate, 0.5 part of anti-aging agent, 5 parts of zinc oxide and conductive carbon 3 parts of black (average particle size: 18 nm, volume resistivity: 0.2 Ω · cm) was kneaded for 10 minutes in a closed mixer adjusted to 50 ° C. to prepare a raw material compound.

  A two-roll machine in which 1% by mass of sulfur (vulcanizing agent) and 1.5% by mass of a vulcanization accelerator are added to the raw material compound with respect to the epichlorohydrin rubber terpolymer and cooled to 20 ° C. And kneading for 10 minutes to obtain an elastic layer compound.

  The elastic layer compound is extruded on an adhesive-coated support by an extrusion molding machine so as to form a roller shape having an outer diameter of about 18 mm, and then in an electric oven at 160 ° C. for 1 hour. After vulcanization and curing of the adhesive, both ends of the rubber were cut off and the surface was polished so as to have a roller shape with an outer diameter of 16 mm to form an elastic layer on the support. At this time, the crown amount (160 mm from the central portion and the difference in outer diameter at the distant position) was 180 μm.

(Charging member production example 1)
Methyl isobutyl ketone was added to a caprolactone-modified acrylic polyol solution (trade name: Plaxel DC2016, manufactured by Daicel Chemical Industries, Ltd.) to adjust the solid content to 13% by mass.

  To 500 parts of this solution (65 parts of polyol), composite particles B-1: 40 parts, modified dimethyl silicone oil (trade name: SH28PA, manufactured by Toray Dow Corning Silicone Co., Ltd.) 0.08 parts , Hexamethylene diisocyanate (HDI) (trade name: Duranate TPA-B80E, manufactured by Asahi Kasei Kogyo) and isophorone diisocyanate (IPDI) (trade name: Bestanat B1370, manufactured by Degussa Huls), a 1: 1 mixture of each butanone oxime block. : 35 parts was added to prepare a mixed solution. At this time, the mixture of HDI and IPDI was added so that “NCO / OH = 0.8”.

  In a 450 ml glass bottle, 250 parts of the above mixed solution and 200 parts of glass beads having an average particle diameter of 0.8 mm as media were mixed and dispersed for 10 hours using a paint shaker disperser to obtain a dispersion solution.

  This surface coating layer coating solution was dipped on the elastic layer once, air-dried at room temperature for 30 minutes or more, then dried in a hot air circulating dryer set at 80 ° C. for 1 hour, and further set at 150 ° C. It dried with the hot air circulation dryer for 1 hour, and formed the surface coating layer on the elastic layer. The dipping coating pulling speed is adjusted so that the initial speed is 20 mm / s and the final speed is 2 mm / s, and the speed varies linearly with time between 20 mm / s and 2 mm / s. I let you.

  Thus, the charging member P1 having the elastic layer and the surface layer in this order on the support was produced. Table 3 shows the prescription of the charging member.

(Charging member production examples 2 to 14)
Charging members 2 to 14 were produced in the same manner as in Production Example 1 except that the type and content of the composite particles in Production Example 1 were changed as shown in Table 3. Table 3 shows the prescription of the charging member.

(Charging member production example 15)
(Production of metal oxide fine particles)
A slurry was prepared by blending 1000 parts of rutile-type titanium oxide fine particles (average particle size 15 nm), 110 parts of isobutyltrimethoxysilane as a surface treating agent, and 3000 parts of toluene as a solvent.

  This slurry was mixed with a stirrer for 30 minutes, and then supplied to Viscomill in which 80% of the effective internal volume was filled with glass beads having an average particle diameter of 0.8 mm, and wet crushing was performed at a temperature of 35 ± 5 ° C. .

  The slurry obtained by the wet pulverization treatment was subjected to vacuum distillation using a kneader (bath temperature: 110 ° C., product temperature: 30 to 60 ° C., degree of vacuum: about 100 Torr), and surfaced at 120 ° C. for 2 hours. The treating agent was baked. The fine particles after the baking treatment were cooled to room temperature and then pulverized with a pin mill to prepare titanium oxide fine particles having a relative dielectric constant of 114.

  A charging member 15 was produced in the same manner as in Production Example 1 except that the titanium oxide fine particles were further added and the content was changed as shown in Table 3. Table 3 shows the prescription of the charging member.

<Examples 1-31 and Comparative Examples 1-13>
As an image forming apparatus for carrying out the image forming method of the present invention, an organic photoconductor digital copying machine using a laser beam (manufactured by Canon Inc .: GP405) was prepared. The outline of the apparatus is that a charging roller is provided as a charging means for the photosensitive member, a holding member for holding the cleaning member is provided for cleaning the charging roller, and a non-woven pad member is provided as the cleaning member. The developer and the photosensitive member are not in contact with each other and a one-component developing device adopting a one-component jumping development method is provided, a transfer roller is provided as a transfer means, a blade cleaning means, and a pre-charge exposure means. Further, the photosensitive member charger, the cleaning unit, and the photosensitive member are integrated units. The process speed was 210 mm / s, and the DC voltage to the developing sleeve was -550V.

  The toner of the image forming apparatus is filled with the toner prepared above in the developing device, the charging roller is removed, and the toner is adjusted and mounted on the charging roller prepared above, and the DC component is applied by the voltage component applied to the charging roller. Modifications were made so that a constant voltage of −750V was obtained.

  Further, when using a toner prepared using toner particles 4, a metal carrier having a surface roughened by removing the resin coat portion covering the surface of the developer carrier provided in the developing device, and did.

  Further, in the case of using a toner prepared using the toner particles 5, a developing device in which the development portion is modified from a one-component jumping development so that a two-component developer can be used was used. The developer is composed of a Cu—Zn ferrite carrier whose surface has a volume average particle diameter of 50 μm and coated with a silicone resin, and a negatively chargeable non-magnetic toner produced using the toner particles 5 described above for the carrier. A two-component development method was used using a developer. The toner and the carrier were mixed at a mass ratio of 7: 100. The development voltage in this case was obtained by superimposing a 1000 Vpp / 3 kHz rectangular wave on a DC component of −500 V.

  Evaluation was performed using the image forming apparatus according to the following evaluation method.

<Evaluation 1>
In an environment of 20 ° C / 5% RH, endured 10,000 sheets of an A4 horizontal image with an image ratio of 20% intermittently. After the endurance, replace only the photosensitive member with an unused photosensitive member, and develop bias. The DC voltage component is approximately the same as the potential on the photoconductor at the development position, and without halftone density (analog halftone) image output and normal halftone, solid white without image exposure. Images were imaged, and resistance unevenness due to surface contamination of the charging roller and scratches on the surface layer were evaluated according to the following evaluation items.
A: Analog halftone, no streak or uneven charging failure occurred, and a uniform image was obtained.
○: A slight streak-like charging failure occurred in the analog halftone, but an image having no problem was obtained in a normal halftone image.
O: streaks in analog halftone, slightly uneven charging due to uneven density due to resistance unevenness, and slight streaky charging in normal halftone images, but no problem with solid white images.
Δ: A streaky or uneven charging failure occurs in an analog halftone, a slight streak or uneven charging failure occurs even in a normal halftone image, and a streaky charging failure occurs even in a solid white image .
X: A streaky or uneven charging failure occurred in the analog halftone, and a fogged image, streak, or uneven image failure due to a charging failure occurred in a normal halftone image or a solid white image.

<Evaluation 2>
In a 20 ° C./5% RH environment, 50,000 sheets of A4 horizontal images with an image ratio of 3% are continuously durable. After the durability, only the charging roller is replaced with an unused charging member, and the development bias is DC. The voltage component is approximately the same as the potential on the photoconductor at the development position, and an image of halftone density (analog halftone) is drawn without image exposure, and the photoconductor-like scratches and melts. The wear was evaluated according to the following evaluation items.
A: An analog halftone image with no streak, unevenness, or poor charging due to fusion, and a uniform image was obtained.
◯: An image having no problem with a normal halftone image was obtained even though a slight streak-like or spot-like charge failure occurred in an analog halftone.
Δ: A streak-like or spot-like charge failure occurred in an analog halftone, and a slight streak-like charge failure occurred even in a normal halftone image.
X: Streaky, uneven, or uneven charging failure occurred in analog halftone, and a fogged image due to charging failure occurred in a normal halftone image or a solid white image.

<Evaluation 3>
Durability of 30,000 sheets of A4 horizontal images with an image ratio of 5% in an environment of 24 ° C / 60% RH was continuously performed, and the mass change before and after the endurance of the drum cartridge (amount of waste toner in the cleaner g) and durability The amount of developer used (consumption amount g) was measured, transfer efficiency was determined from the following formula, and evaluation was performed according to the following evaluation items:
(Consumption-Waste toner amount) / Consumption x 100 (%)
◎: 93% or more ○: 90% or more and less than 93% △: 85% or more and less than 90% ×: less than 85%

<Evaluation 4>
Under an environment of 23 ° C / 5% RH, A3 image output is performed on the image chart, where the one end of the drum at the end of the image is solid black and the subsequent portion is halftone, and the evaluation of the ghost image is as follows. Evaluation was performed according to the items.
(Double-circle): The image of a halftone part is uniform and a density difference is hardly seen.
◯: A level at which there is a slight difference between the halftone image density for one round of the drum immediately after solid black and the halftone image density after that, and a level difference can be confirmed.

  FIG. 4 below shows the points of the charging member and the toner evaluated in Examples and Comparative Examples, and Tables 4 and 5 below show the evaluation results of the charging members and toners used for the durability of the Examples and Comparative Examples.

1 is a schematic configuration diagram illustrating an example of a specific image forming apparatus of the present invention. It is a schematic block diagram which shows an example of a charging roller. FIG. 6 is a diagram illustrating a correlation between an average circularity C of toner and a number average particle diameter Dc of composite particles. It is a figure which shows the number average particle diameter Dc of the composite particle contained in the surface layer of the charging member evaluated by the Example and the comparative example, and the point of the circularity C of a toner.

Explanation of symbols

1 Electrophotographic photoreceptor (photoreceptor drum)
DESCRIPTION OF SYMBOLS 2 Cleaning apparatus 3 Fixing device 4 Cleaning elastic blade 5 Transfer material 6 Primary charging roller 6-1 Conductive support body 6-2 Elastic layer 6-3 Surface layer 7 Developer 7-1 Developing sleeve 7-2 Developer stirring device 8 Transfer roller 9 Primary charging roller cleaning member L Exposure light

Claims (10)

Charging the photosensitive member having at least a photosensitive layer and a protective layer on a support, which is an image carrier, by charging the charging member; and
An electrostatic latent image forming step of forming an electrostatic latent image on a charged photoreceptor;
A development step of developing the toner carried on the toner carrier into the electrostatic latent image to form a toner image;
A transfer step of transferring the toner image formed on the image carrier onto a transfer material with or without an intermediate transfer member;
A transfer step for electrostatic transfer to the transfer material;
And the toner has a colorant and a binder resin and the average circularity (C) is 0.930 or more and 0.995 or less.
An image forming method comprising composite particles having a number average particle diameter Dc (nm) in which the core particle A is coated with carbon black as the conductive particles on the surface layer of the charging member and satisfying the range of the following formula: :
5 ≦ Dc ≦ 7000− (7000 × C)   The image forming method according to claim 1, wherein the composite particles have a number average particle diameter Dc of 10 ≦ Dc ≦ 4500− (4500 × C).   The image forming method according to claim 1, wherein the toner has an average circularity (C) of 0.960 or more and 0.995 or less.   The composite image contained in the said surface layer is 10 mass parts or more and 120 mass parts or less with respect to 100 mass parts of binder resin used for a surface layer, The image formation in any one of Claims 1-3 Method.   A metal oxide in which the core particle A is selected from the group consisting of silica, alumina, titanium oxide, zinc oxide, magnesium oxide, iron oxide, strontium titanate, calcium titanate, magnesium titanate, barium titanate and calcium zirconate. The image forming method according to claim 1, wherein the image forming method is fine particles a.   The image forming method according to claim 5, wherein the core particles A are surface-treated with an organosilicon compound.   The surface layer of the charging member further contains metal oxide fine particles b having a relative dielectric constant of 50 or more and 300 or less selected from the group consisting of strontium titanate, calcium titanate, barium titanate and rutile type titanium oxide particles. The image forming method according to claim 1.   The image forming method according to any one of claims 1 to 7, wherein an inorganic fine powder of a perovskite crystal having an average particle diameter of 300 to 3000 nm is further added to the toner particles.   The addition amount of the inorganic fine powder of the perovskite crystal having an average particle diameter of 300 to 3000 nm is 0.1 parts by mass or more and 5.0 parts by mass or less with respect to 100 parts by mass of the toner particles. Image forming method. An electrophotographic photosensitive member; and a charging unit configured to charge the photosensitive member by applying a voltage to a charging member disposed in contact with the photosensitive member. In a process cartridge in which at least one means selected from the group consisting of a developing means, a cleaning means, and a transfer means that develops a toner image and is supported integrally with the charging means and is detachable from the electrophotographic apparatus main body,
The toner has a colorant and a binder resin and an average circularity (C) of 0.930 or more and 0.995 or less. The surface layer of the charging member is coated with conductive particles, and the core particles A are coated with carbon black. A process cartridge comprising composite particles having a number average particle diameter Dc (nm) satisfying a range of the following formula:
5 ≦ Dc ≦ 7000− (7000 × C)

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