JP5573536B2 - Electrostatic image developer, developer cartridge, process cartridge, image forming apparatus, and image forming method - Google Patents

Description

The present invention relates to an electrostatic charge image developer, a developer cartridge, a process cartridge, an image forming apparatus, and an image forming method.
About.

  A method of visualizing image information through an electrostatic latent image (electrostatic image) such as electrophotography is currently used in various fields. Conventionally, in electrophotography, an electrostatic image is formed on a photosensitive member or electrostatic recording member using various means, and particles called toner are attached to the electrostatic image to develop the electrostatic image. A method is generally used in which a toner image (development image) is visualized through a plurality of steps of transferring the toner image onto the surface of a transfer medium and fixing it by heating or the like.

Conventionally, it is known that resin particles or the like are added to toners and developers for the purpose of assisting charging of the toner, stabilizing the chargeability of the toner, and the like.
For example, Patent Document 1 is characterized in that the toner is surface-treated with polymethyl methacrylate powder particles that are positively charged with respect to the carrier and whose average particle size is smaller than that of toner particles. An electrophotographic developer is disclosed. Further, Patent Document 2 discloses a developer characterized in that, in an external addition process of an electrophotographic developer, a toner is subjected to a surface treatment of polymethylmethacrylate particles charged on the plus side with respect to a carrier. It is disclosed.

  Patent Document 3 discloses an image carrier, a charging unit that charges the image carrier at a contact portion to form an electrostatic image on the image carrier, and a charging process performed by the charging unit. An exposure means as means for writing an electrostatic latent image on the image carrier, a developing means for supplying toner to the electrostatic latent image formed on the image carrier for visualization, and a visualized toner image as a transfer material An image forming apparatus using a cleanerless system that collects toner remaining on the surface of the image carrier without being transferred by the transfer means by the developing device. An image forming apparatus is disclosed in which fine particles having a polarity opposite to the charged polarity of the toner are externally added to the toner developed by the above method. Patent Document 4 discloses a suspension polymerization method having a colored suspension resin particle having a practical sphericity of 0.90 to 1.00 and an external additive containing at least a colorant and a low softening point substance. In the toner, a) the content of the low softening point substance is 5 to 30% by weight with respect to the suspension polymerization toner, and b) the external additive is reverse to the suspension polymerization toner. Resin fine particles that are polar and have an average particle size of 0.01 to 1 μm and a practical sphericity of Wardel of 0.90 to 1.00, and inorganic fine particles having an average particle size smaller than the resin fine particles, A suspension polymerization toner is disclosed.

  Further, in Patent Document 5, in the developer for developing an electrostatic charge image containing a toner externally added with inorganic oxide fine particles and a carrier, the inorganic oxide fine particles have a volume average particle diameter of 20 to 300 nm. And the developer contains non-adhesive resin particles with a volume average particle diameter of 0.5 to 8.0 μm, and the resin particles are coated with the inorganic oxide. A developer for developing an electrostatic charge image characterized in that the ratio is in the range of 2 to 70% is disclosed. Patent Document 6 discloses a developer that carries a developer containing toner and a carrier, develops an electrostatic latent image on the latent image carrier with toner, and a developer that has completed development by the developer. Of the developer including the collected toner supplied by the collected toner supply means and the collected toner supplied by the collected toner supply means, a developer to be discarded is supplied. In a developing device comprising: a developer discharging means for discharging; and a new developer supplying means for supplying a new developer including a carrier to the developer from which the developer to be discarded has been discharged by the developer discharging means. The developer further includes an auxiliary agent for suppressing wear of the latent image carrier, and the auxiliary agent has a charging polarity opposite to that of the toner. Is disclosed That.

On the other hand, in an electrophotographic image forming apparatus, there is a blade type cleaner that scrapes off deposits such as residual toner by bringing a cleaning blade into contact with the surface of the photoreceptor drum in order to remove the deposits on the photoreceptor drum. Widely used. In a blade type cleaner, a lubricant is applied to a cleaning blade or the like for the purpose of preventing the blade from turning over or preventing the generation of a charged memory.
For example, in Patent Document 7, the image is moved by moving the image relative to the image carrier in a state where the toner image is temporarily in contact with the image carrier until the image is transferred. In the method of applying a lubricant to a cleaning blade, the lubricant is applied to the cleaning blade to remove deposits adhering to the surface of the carrier, and the lubricant causes the image carrier surface to be removed by friction with the image carrier. The cleaning blade is made of a material that is charged within a range of 100 V, and the lubricant is dispersed in a solvent that does not evaporate between the start of application and the end of application. A method of applying a lubricant to a cleaning blade is disclosed.

JP-A-5-333586 JP-A-7-092732 JP-A-2005-300751 JP-A-5-313416 JP 2002-156782 A JP 2006-220852 A JP 2001-051564 A

An object of the present invention is to provide an electrostatic charge image developer capable of suppressing fluctuations in image density.
Another object of the present invention is to provide a developer cartridge, a process cartridge, an image forming apparatus, and an image forming method using the electrostatic image developer.

The above-described problems of the present invention have been solved by the means described in <1>, <7> to <9> and <11> below. It is shown below together with <2> to <6>, <10> and <12> which are preferred embodiments.
<1> A toner having colored particles containing at least a colorant and a binder resin, externally added with inorganic particles on the surface of the colored particles, a shape factor SF1 of 100 to 120, and a shape factor An electrostatic charge image comprising: a carrier having SF2 of 100 to 120; and resin particles that exist in a state independent of the toner and are charged with a polarity opposite to that of the inorganic particles by stirring with the carrier. Developer,
<2> The electrostatic charge image developer according to <1>, wherein the volume average particle diameter of the resin particles is larger than the volume average particle diameter of the inorganic particles.
<3> The electrostatic charge image developer according to <1> or <2>, wherein at least one of the inorganic particles is inorganic particles having a volume average particle diameter of 100 to 500 nm.
<4> The electrostatic charge image developer according to any one of <1> to <3>, wherein the resin particles have a volume average particle diameter of 200 to 4,000 nm.
<5> The electrostatic charge image developer according to any one of <1> to <4> above, wherein the resin particles are particles containing polymethyl methacrylate,
<6> The amount of the resin particles added is 0.1 to 5% by weight with respect to the total weight of the colored particles, according to any one of the above <1> to <5> An electrostatic charge image developer,
<7> At least a developer is accommodated and detachable from an image forming apparatus, and the developer is the electrostatic charge image developer according to any one of the above items <1> to <6>. Developer cartridge,
<8> A process comprising at least a developer holder, detachable from an image forming apparatus, and containing the electrostatic charge image developer according to any one of <1> to <6> above. cartridge,
<9> At least a photosensitive member, a charging unit that uniformly charges the photosensitive member, an electrostatic latent image forming unit that exposes the charged photosensitive member to form an electrostatic latent image, and the photosensitive member And developing means for developing the electrostatic latent image formed as a toner image with the electrostatic charge image developer according to any one of <1> to <6>, and formed on the photoreceptor. An image forming apparatus comprising: a transfer unit that transfers a toner image onto a transfer target; and a fixing unit that fixes the toner image transferred onto the transfer target;
<10> The developing unit includes a developer holder that supplies the electrostatic charge image developer to the photosensitive member, and the developer is discharged from the developing unit below the developer holder in the gravitational direction. The image forming apparatus according to <9>, further comprising storage means for storing resin particles,
<11> A charging step for uniformly charging the photoconductor, an electrostatic latent image forming step for exposing the charged photoconductor to form an electrostatic latent image, and the static image formed on the photoconductor A developing process for developing the electrostatic latent image as a toner image with the electrostatic charge image developer according to any one of <1> to <6>, and a toner image formed on the photoreceptor. An image forming method comprising: a transfer step of transferring the toner image; and a fixing step of fixing the toner image transferred onto the transfer target;
<12> The image forming method according to <11>, further comprising an accumulation step of accumulating the resin particles discharged in the development step.

According to the invention described in <1> above, a carrier having a shape factor SF1 of 100 to 120 and a shape factor SF2 of 100 to 120 exists in a state independent of the toner, and is inorganic by stirring with the carrier. It is possible to provide an electrostatic charge image developer capable of suppressing fluctuations in image density as compared with a case where resin particles that are charged with a polarity opposite to that of the particles are not provided.
According to the invention described in <2> above, the electrostatic charge image developer that can further suppress fluctuations in image density as compared with the case where the volume average particle diameter of the resin particles is equal to or smaller than the volume average particle diameter of the inorganic particles. Can be provided.
According to the invention described in the above <3>, the image density can be changed without impairing the storage stability as compared with the case where at least one of the inorganic particles is an inorganic particle having a volume average particle diameter of less than 100 nm or more than 500 nm. An electrostatic charge image developer that can be further suppressed can be provided.
According to the invention described in <4> above, an electrostatic charge image developer capable of further suppressing fluctuations in image density is provided as compared with the case where the volume average particle diameter of the resin particles is less than 200 nm or more than 4,000 nm. be able to.
According to the invention described in <5> above, it is possible to provide an electrostatic charge image developer that can further suppress fluctuations in image density as compared with the case where the resin particles do not contain polymethyl methacrylate.
According to the invention described in <6> above, fluctuations in the image density are further suppressed as compared with the case where the addition amount of the resin particles is less than 0.1% by weight or more than 5% by weight with respect to the total weight of the colored particles. An electrostatic charge image developer that can be provided can be provided.
According to the invention described in <7> above, it is possible to provide a developer cartridge containing an electrostatic charge image developer capable of suppressing fluctuations in image density as compared with the case where the present configuration is not provided.
According to the invention described in <8> above, it is possible to provide a process cartridge in which an electrostatic charge image developer capable of suppressing fluctuations in image density is accommodated as compared with the case where this configuration is not provided.
According to the invention described in <9>, it is possible to provide an image forming apparatus capable of suppressing fluctuations in image density as compared with the case where the present configuration is not provided.
According to the invention described in <10> above, it is possible to provide an image forming apparatus capable of preventing contamination in the image apparatus as compared with the case where this configuration is not provided.
According to the invention described in <11> above, it is possible to provide an image forming method capable of suppressing fluctuations in image density as compared with the case where the present configuration is not provided.
According to the invention described in <12> above, it is possible to provide an image forming method capable of preventing contamination in the image apparatus as compared with the case where this configuration is not provided.

1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an exemplary embodiment. It is a schematic block diagram which shows an example of the process cartridge of this embodiment.

(1) Electrostatic image developer The electrostatic image developer of the present embodiment has colored particles containing at least a colorant and a binder resin, and is formed by externally adding inorganic particles to the surface of the colored particles. A toner having a shape factor SF1 of 100 to 120 and a shape factor SF2 of 100 to 120, and a carrier independent of the toner, and having a polarity opposite to that of the inorganic particles due to friction with the carrier And charged resin particles.
Hereinafter, this embodiment will be described in detail. In addition, in the following description, the description of “A to B” representing a numerical range is synonymous with “A or more and B or less” unless otherwise specified, and means a numerical range including A and B as end points. .

In conventional electrostatic charge image developers, when some of the inorganic particles (inorganic external additives) externally added to the surface of the colored particles constituting the toner are released and migrate to the surface of the carrier, the image density changes. In addition, the color gamut sometimes fluctuated in the case of a color image. This is considered to be a result of the macro resistance of the developer being increased because the inorganic particles migrated to the surface of the carrier are interposed in the contact portion between the plurality of carriers, and the electrical resistance in the aggregate of carriers is increased. .
The externally added inorganic particles have, for example, a volume average particle diameter that exhibits an effect as an inclusion between toners (hereinafter also referred to as “spacer effect”) for the purpose of improving the storage property of the toner. Large-diameter inorganic particles (large-diameter inorganic external additives) of 100 nm or more may be used. Such large-diameter inorganic particles are easily released from the toner. For this reason, when large-diameter inorganic particles are used, a spacer effect due to the large-diameter inorganic particles is manifested between a plurality of carriers, and the macro resistance of the developer is significantly increased. Variations and color gamut variations will increase.

On the other hand, the electrostatic charge image developer of the present embodiment exists in an independent state from the toner with respect to the inorganic particles externally added to the surface of the colored particles constituting the toner, and the inorganic particles are obtained by stirring with the carrier. It has resin particles that are charged to the opposite polarity. The state independent of the toner means a state where the toner is not fixed to the surface of the toner and can move separately from the toner in the developer.
In the electrostatic charge image developer of this embodiment, the resin particles are agitated with the carrier to cause friction with the carrier and are charged with a polarity opposite to that of the inorganic particles. Therefore, the inorganic particles released from the toner are electrostatically charged. It is trapped in the resin particles by a strong force. For this reason, the transfer of inorganic particles to the surface of the carrier is suppressed. As a result, it is considered that an increase in the resistance of the developer is suppressed, and a change in image density and a change in color gamut are suppressed.

  Further, in the present embodiment, by making the volume average particle diameter of the resin particles larger than the volume average particle diameter of the inorganic particles, the inorganic particles are physically fixed to the surface of the resin particles by the force when the developer is stirred. In combination with the electrostatic force described above, the trapping efficiency of the inorganic particles is improved.

  Furthermore, in this embodiment, by using spherical resin particles having an average circularity of 0.974 or more, the mobility of the resin particles on the carrier surface is excellent. The resin particles having such excellent mobility move while rolling on the carrier surface, and capture inorganic particles with high efficiency in combination with the electrostatic force described above.

  It is considered that the resin particles capturing the inorganic particles as described above have a small absolute value of the charge amount. For this reason, the resin particles that have captured the inorganic particles are easily discharged by centrifugal force in the developer holder, and the resin particles that have captured the inorganic particles during development are difficult to be developed on the photoreceptor. As a result, the photoreceptor is less likely to be damaged by the resin particles capturing the inorganic particles.

(toner)
In this embodiment, the toner (also referred to as “electrostatic image developing toner”) has colored particles containing at least a colorant and a binder resin, and inorganic particles are externally added to the surface of the colored particles. It will be.

<Colored particles>
In the present embodiment, the colored particles contain at least a colorant and a binder resin. The colored particles may contain other components such as a release agent in addition to these components.

-Binder resin-
In this embodiment, the binder resin is not particularly limited, but from the viewpoint of low-temperature fixability, image strength, and offset durability against polyvinyl chloride (hereinafter also referred to as “vinyl chloride offset resistance”), a polyester resin. It is preferable that the resin composition contains an amorphous (also referred to as “non-crystalline”) polyester resin. The polyester resin is synthesized, for example, mainly by condensation polymerization of polyvalent carboxylic acids and polyhydric alcohols.
In the present embodiment, the “amorphous polyester resin” is not a clear endothermic peak in differential scanning calorimetry (hereinafter sometimes abbreviated as “DSC”) but a stepped shape. It refers to a resin that shows an endothermic change.

  Examples of the polyvalent carboxylic acid include aromatic carboxylic acids such as terephthalic acid, isophthalic acid, phthalic anhydride, trimellitic anhydride, pyromellitic acid, naphthalenedicarboxylic acid; maleic anhydride, fumaric acid, succinic acid, alkenyl Aliphatic carboxylic acids such as succinic anhydride and adipic acid; and alicyclic carboxylic acids such as cyclohexanedicarboxylic acid. These polyvalent carboxylic acids may be used alone or in combination of two or more. Among these polyvalent carboxylic acids, it is preferable to use an aromatic carboxylic acid. For the purpose of ensuring good fixability, it is preferable to use a trivalent or higher carboxylic acid (trimellitic acid or its acid anhydride) together with a dicarboxylic acid in order to form a crosslinked structure or a branched structure.

Examples of the polyhydric alcohol include aliphatic diols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, and neopentyl glycol; cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A, and the like. Alicyclic diols; aromatic diols such as bisphenol A ethylene oxide adducts and bisphenol A propylene oxide adducts. These polyhydric alcohols may be used alone or in combination of two or more.
Among these polyhydric alcohols, aromatic diols and alicyclic diols are preferable, and among these, aromatic diols are more preferable. In addition, in order to secure better fixability, a trihydric or higher polyhydric alcohol (for example, glycerin, trimethylolpropane, pentaerythritol, etc.) is used in combination with a diol in order to take a crosslinked structure or a branched structure. Also good.

  The glass transition temperature (hereinafter sometimes abbreviated as “Tg”) of the amorphous polyester resin is preferably 50 to 80 ° C., more preferably 50 to 70 ° C. When Tg is 80 ° C. or lower, the low-temperature fixability is excellent. Further, when the Tg is 50 ° C. or higher, the heat resistant storage stability is excellent, and the fixed image storage stability is excellent.

  In this embodiment, the content of the amorphous polyester resin in the colored particles is preferably 50 to 96% by weight, more preferably 60 to 94% by weight, and more preferably 65 to 92% by weight, with the total weight of the colored particles being 100% by weight. % Is more preferable. When the content of the amorphous polyester resin is within the above range, the vinyl chloride offset resistance is good, and when the resin particles are amorphous polyester resin particles, the compatibility is improved and the large-diameter inorganic external additive is added. Inhibition of adhesion during fixing by the agent is suppressed.

  The acid value of the amorphous polyester resin is preferably 5 to 25 mgKOH / g. If the acid value is 5 mgKOH / g or more, the toner has good affinity for paper and good chargeability. In addition, when the toner is produced by the emulsion aggregation method described later, it is easy to produce emulsion particles, and it is suppressed that the speed of aggregation in the aggregation process of the emulsion aggregation method and the speed of shape change in the fusion process are increased. Easy to control grain size and shape. In addition, if the acid value of the amorphous polyester resin is 25 mgKOH / g or less, the environmental dependency of charging is not adversely affected. In addition, a decrease in the aggregation rate in the aggregation step and the change rate of the shape in the fusing step in the production of toner by the emulsion aggregation method can be suppressed, and productivity does not decrease. The acid value of the amorphous polyester resin is more preferably 6 to 23 mgKOH / g.

  The weight average molecular weight (Mw) of the amorphous polyester resin is preferably 5,000 to 1,000,000, and more preferably 7,000 to 500,000. The number average molecular weight (Mn) of the amorphous polyester resin is preferably 2,000 to 100,000. Moreover, 1.5-100 are preferable and, as for molecular weight distribution Mw / Mn, 2-60 are more preferable. It is preferable that the weight average molecular weight, number average molecular weight, and molecular weight distribution of the amorphous polyester resin are within the above ranges because excellent fixed image strength can be obtained without impairing the low-temperature fixability.

  In this embodiment, the weight average molecular weight and the number average molecular weight of the polyester resin are measured and calculated by GPC (Gel Permeation Chromatography). Specifically, HPC-8120 manufactured by Tosoh Corporation is used for GPC, TSKgel SuperHM-M (15 cm) manufactured by Tosoh Corporation is used for the column, and the polyester resin is dissolved in a THF (tetrahydrofuran) solvent. Is done. Next, the molecular weight of the polyester resin is calculated using a molecular weight calibration curve created with a monodisperse polystyrene standard sample.

  In the present embodiment, the colored particles may contain a crystalline polyester resin. The crystalline polyester resin is compatible with the amorphous polyester resin when melted to lower the toner viscosity, so that a toner having better low-temperature fixability can be obtained. Further, among the crystalline polyester resins, aromatic crystalline polyester resins are generally higher than the melting temperature range described later, and therefore when the crystalline polyester resin is included, the aromatic crystalline polyester resin is more preferably an aliphatic crystalline polyester resin. preferable.

  In the present embodiment, the content of the crystalline polyester resin in the colored particles is preferably 2 to 30% by weight, more preferably 4 to 25% by weight, with the total weight of the colored particles being 100% by weight. When the content is 2% by weight or more, the low-temperature fixability is improved because the amorphous polyester resin has a low viscosity at the time of melting. On the other hand, if the amount is 30% by weight or less, the deterioration of the charging property of the toner due to the presence of the crystalline polyester resin is prevented, and a high image strength after fixing on the recording medium (transfer medium) is easily obtained.

  The melting temperature of the crystalline polyester resin is preferably in the range of 50 to 90 ° C, more preferably in the range of 55 to 90 ° C, and still more preferably in the range of 60 to 90 ° C. When the melting temperature is 50 ° C. or higher, the toner storage stability and the toner image storage stability after fixing are excellent. Moreover, if it is 90 degrees C or less, low temperature fixability will improve.

  In the present embodiment, the “crystalline polyester resin” refers to a resin having a clear endothermic peak instead of a stepwise endothermic change in DSC. The crystalline polyester resin is a polymer obtained by copolymerizing other components with respect to the main chain. When the other components are less than 50% by weight, the copolymer is also called crystalline polyester.

  The crystalline polyester resin is synthesized from an acid (dicarboxylic acid) component and an alcohol (diol) component. In the following, the “acid-derived structural unit” refers to a polyester resin before the synthesis of the polyester resin. Refers to a structural unit that was an acid component, and “alcohol-derived structural component” refers to a structural unit that was an alcohol component before the synthesis of the polyester resin.

Examples of the acid component serving as the acid-derived structural unit include various dicarboxylic acids, and linear aliphatic dicarboxylic acids are preferable.
Examples of the acid component include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1 , 11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, etc. Examples thereof include, but are not limited to, lower alkyl esters and acid anhydrides. Among these, adipic acid, sebacic acid, and 1,10-decanedicarboxylic acid are preferable in consideration of availability.
The crystalline polyester resin may contain structural units such as a structural unit derived from a dicarboxylic acid having a double bond and a structural unit derived from a dicarboxylic acid having a sulfonic acid group as an acid-derived structural unit.

  As alcohol which becomes a structural unit derived from alcohol, aliphatic diol is preferable, for example, ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1 , 7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-dodecanediol, 1,12-undecanediol, 1,13-tridecanediol, , 14-tetradecanediol, 1,18-octadecanediol, 1,20-eicosanediol and the like, but are not limited thereto. Among these, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol are preferable in consideration of cost.

  The molecular weight (weight average molecular weight; Mw) of the crystalline polyester resin is preferably 8,000 to 40,000, from the viewpoints of resin manufacturability, resin dispersion during toner production, and compatibility during melting. 30,000 to 30,000 is more preferable. If the weight average molecular weight is 8,000 or more, a decrease in resistance of the crystalline polyester resin is suppressed, so that a decrease in chargeability is prevented. On the other hand, if it is 40,000 or less, the cost of resin synthesis is suppressed, and a decrease in meltability is prevented, so that the fixability is not adversely affected.

  There is no restriction | limiting in particular as a manufacturing method of a polyester resin, The polymerization method of the well-known polyester resin which makes an acid component and an alcohol component react is illustrated. For example, the polyester resin is produced by properly using direct polycondensation, transesterification method, and the like depending on the types of the acid component and the alcohol component. The molar ratio (acid component / alcohol component) at the time of reacting the acid component and the alcohol component varies depending on the reaction conditions and the like, and thus cannot be generally specified. However, in order to increase the molecular weight, the molar ratio ( (Acid group acidic group / alcohol component hydroxy group) is preferably 1 / 0.95 to 1 / 1.05.

  Catalysts used in the production of the polyester resin include alkali metal compounds such as sodium and lithium; alkaline earth metal compounds such as magnesium and calcium; metal compounds such as zinc, manganese, antimony, titanium, tin, zirconium and germanium; Phosphorous acid compound; Phosphoric acid compound; Amine compound; Sulfuric acid such as sulfuric acid, alkyl sulfuric acid, alkylbenzene sulfonic acid, alkoxybenzene sulfonic acid and the like.

  In addition to the polyester resin, other resins are also used as the binder resin. Other resins include ethylene resins such as polyethylene and polypropylene; styrene resins such as polystyrene and α-polymethylstyrene; (meth) acrylic resins such as polymethyl (meth) acrylate and poly (meth) acrylonitrile; polyamide resins , Polycarbonate resin, polyether resin and copolymer resins thereof.

  The content of the other resin in the colored particles is preferably 1.0 to 12% by weight, more preferably 2.0 to 11% by weight, with the total weight of the entire colored particles being 100% by weight, and 2.5 to 10% by weight is more preferred. When the content of other resins is within the above range, sufficient coloring power can be obtained without impairing the low-temperature fixability.

-Colorant-
The colored particles contain a colorant. The colorant may be a dye or a pigment, but a pigment is used from the viewpoint of light resistance and water resistance. Further, the colorant is not limited to a colored colorant, and includes a white colorant and a colorant having a metal color.
Examples of colorants include carbon black, aniline black, aniline blue, calcoil blue, chrome yellow, ultramarine blue, dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, and rose. Bengal, Quinacridone, Benzidine Yellow, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 185, C.I. I. Pigment red 238, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 180, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 74, C.I. I. Pigment blue 15: 1, C.I. I. A known pigment such as CI Pigment Blue 15: 3 is used.

In this embodiment, the content of the colorant in the electrostatic image developing toner is preferably 1 to 30 parts by weight with respect to 100 parts by weight of the binder resin.
It is also effective to use a surface-treated colorant or a pigment dispersant. By selecting the type of the colorant, yellow toner, magenta toner, cyan toner, black toner and the like are prepared.

-Release agent-
One embodiment of the colored particles includes colored particles containing a release agent. Examples of the release agent include paraffin wax such as low molecular weight polypropylene and low molecular weight polyethylene; silicone resin; rosins; rice wax; carnauba wax; 50-100 degreeC is preferable and, as for the melting temperature of these mold release agents, 60-95 degreeC is more preferable.
The content of the release agent in the colored particles is preferably 0.5 to 15% by weight, and more preferably 1.0 to 12% by weight. If the content of the release agent is 0.5% by weight or more, peeling failure particularly in the case of oilless fixing is prevented. If the content of the release agent is 15% by weight or less, deterioration of toner fluidity can be prevented, and image quality and image formation reliability can be maintained.

-Other additives-
In addition to the components as described above, various components such as an internal additive and a charge control agent may be added to the colored particles according to the present embodiment as necessary.
Examples of the internal additive include metals such as ferrite, magnetite, reduced iron, cobalt, nickel, manganese, alloys, and magnetic materials such as compounds containing these metals.
Examples of the charge control agent include quaternary ammonium salt compounds, nigrosine compounds, dyes composed of complexes of aluminum, iron, chromium, and triphenylmethane pigments.

<Inorganic particles>
In this embodiment, the toner for developing an electrostatic charge image has inorganic particles (inorganic external additives) externally added to the surface of the colored particles.
Examples of inorganic particles include silica particles, titanium oxide particles, alumina particles, cerium oxide particles, and the like, but silica particles are used because they have a small effect on cost and color gamut. In particular, silica particles produced by the sol-gel method are preferable because of narrow particle size distribution and high sphericity. The inorganic particles may be subjected to various surface treatments. For example, those subjected to surface treatment with a silane coupling agent, a titanium coupling agent, silicone oil or the like are preferably used.

  In this embodiment, it is more preferable that at least one of the inorganic particles has a volume average particle diameter of 100 to 500 nm. In the present embodiment, inorganic particles having a particle size in the above range are referred to as large-diameter inorganic particles (large-diameter inorganic external additive). In the present embodiment, the volume average particle diameter of the large-diameter inorganic particles is more preferably 100 to 400 nm. When it is 100 nm or more, the spacer effect is sufficiently obtained, and the effect of improving the toner storage property is great. Moreover, when it is 500 nm or less, it adheres to the surface of the colored particles, and desorption / separation is suppressed.

  The addition amount of the large-diameter inorganic particles is preferably 0.1 to 10 parts by weight, more preferably 0.15 to 9 parts by weight, with respect to 100 parts by weight of the colored particles. More preferably, it is 8 parts by weight. When the addition amount of the large-diameter inorganic particles is 0.1 parts by weight or more with respect to 100 parts by weight of the colored particles, storage properties and toner fluidity are improved. In addition, when the amount is 10 parts by weight or less, the colored particles adhere without unevenness.

In the present embodiment, two or more types of large-diameter inorganic particles having different volume average particle diameters may be used as external additives. Moreover, you may use together the inorganic particle (small-diameter inorganic particle) whose volume average particle diameter is less than 100 nm. That is, two types of inorganic particles that are different types of inorganic particles having different volume average particle diameters may be used, and inorganic particles of the same type that have different volume average particle sizes are used in combination. May be.
The volume average particle diameter of the inorganic particles is measured using a laser diffraction particle size distribution measuring device (LS13 320: manufactured by Beckman Coulter, Inc.).

<Toner characteristics>
In the present embodiment, the electrostatic charge image developing toner preferably has a shape factor SF1 of 115 to 140. The closer the toner shape is to a perfect sphere, the more advantageous in terms of developability and transferability, but in terms of cleaning properties, it may be inferior to an indeterminate shape. The shape factor SF1 of the toner is more preferably 120 to 138. When the toner has a shape in the above range, transfer efficiency and image density are improved, high-quality image formation is performed, and the cleaning property of the surface of the photosensitive member (image holding member) is enhanced.

Here, the shape factor SF1 is obtained by the following equation.
SF1 = (ML ² / A) × (π / 4) × 100
In the above formula, ML represents the absolute maximum length of the toner particles, and A represents the projected area of the toner particles.
SF1 is quantified mainly by analyzing a microscope image or a scanning electron microscope (SEM) image using an image analysis apparatus. For example, an optical microscope image of particles dispersed on the surface of a slide glass is transmitted through a video camera. It is calculated by taking in a Luzex image analyzer, obtaining the maximum length and projected area of 100 particles, calculating by the above formula, and determining the average value.

  In this embodiment, the electrostatic charge image developing toner has a volume average particle diameter of preferably 3 to 9 μm, more preferably 3.1 to 8.5 μm, and still more preferably 3.2 to 8.0 μm. When the volume average particle diameter is 3 μm or more, a decrease in toner fluidity is suppressed, and the chargeability of each particle is easily maintained. In addition, the charge distribution is not widened, preventing transfer to the background (non-image area), and the toner is less likely to spill from the developing machine. Further, when the volume average particle diameter of the toner is 3 μm or more, the cleaning property is improved. When the volume average particle diameter is 9 μm or less, a decrease in resolution is suppressed and sufficient image quality is obtained. The volume average particle diameter is measured with a measuring machine such as Coulter Multisizer II (manufactured by Beckman Coulter, Inc.).

  In this embodiment, tan δ (G ″ / G ′) at 110 ° C. of the electrostatic image developing toner is preferably 1.6 or less, more preferably 1.5 or less, and even more preferably 1.4 or less. When G ″ / G ′) is 1.6 or less, a good low-gloss image can be obtained. Note that G ′ represents a storage elastic modulus, and G ″ represents a loss elastic modulus.

<Toner production method>
In the present embodiment, a method for producing colored particles used in the method for producing a toner for developing an electrostatic charge image will be described. The method for producing the colored particles is not particularly limited, and the colored particles are produced by a dry method such as a kneading pulverization method or a wet method such as a melt suspension method, an emulsion aggregation method, or a dissolution suspension method. Especially, it is preferable to manufacture by an emulsion aggregation method.

The emulsion aggregation method is to prepare dispersions (emulsion, pigment dispersion, etc.) each containing components (binder resin, colorant, etc.) contained in the colored particles, and mix these dispersions into colored particles. In this method, the components contained are aggregated to form aggregated particles, and then the aggregated particles are heated to a melting temperature (melting point) or a glass transition temperature of the binder resin to cause thermal aggregation of the aggregated particles.
Emulsion aggregation is easier to produce colored particles with a smaller particle size and narrower particle size distribution than kneading and pulverization, which is a dry method, and melt suspension, dissolution suspension, etc., which are other wet methods. Easy to obtain colored particles. In addition, shape control is easier than in the melt suspension method, dissolution suspension method, and the like, and uniform amorphous colored particles are produced. Furthermore, it is possible to control the structure of the colored particles, such as film formation, and when a release agent or a crystalline polyester resin is contained, these surface exposures are suppressed, thereby preventing deterioration of chargeability and storage stability. The
In the emulsion aggregation method, aggregated particles are preferably prepared by adding a polyvalent metal salt as an aggregating agent. The polyvalent metal forms ionic crosslinks with terminal functional groups of the binder resin during the particle preparation process. To do. That is, the viscoelasticity of the colored particles is controlled by controlling the metal valence and the amount of the remaining metal element.

Next, the manufacturing process of the emulsion aggregation method will be described in detail.
In the emulsion aggregation method, at least an emulsification step of emulsifying raw materials constituting colored particles to form resin particles (emulsion particles), an aggregation step of forming aggregates of the resin particles, and a fusion that fuses the aggregates Process. Hereinafter, an example of the manufacturing process of the colored particles by the emulsion aggregation method will be described for each process.

[Emulsification process]
Examples of the method for preparing the emulsion include a phase inversion emulsification method and a melt emulsification method.
In the phase inversion emulsification method, a resin to be dispersed is dissolved in a hydrophobic organic solvent in which the resin is soluble, and a base is added to the organic continuous phase (Oil phase; O) to neutralize it. Thereafter, by introducing an aqueous medium (Water phase; W), the water in oil (W / O) system is changed to an oil in water (O / W) system, whereby the organic continuous phase in which the resin is present. Phase into a discontinuous phase. As a result, the resin is dispersed and stabilized in the form of particles in the aqueous medium, and an emulsion is prepared.
In the melt emulsification method, an emulsion is prepared by applying a shearing force to a solution in which an aqueous medium and a resin are mixed by a disperser. At that time, particles are formed by heating to lower the viscosity of the resin component. A dispersant may be used to stabilize the dispersed resin particles. Furthermore, when the resin is oily and has a relatively low solubility in water, the resin is dissolved in a solvent in which the resin is dissolved and dispersed in water together with a dispersant and a polymer electrolyte, and then heated or decompressed. You may produce the emulsified liquid which disperse | distributed the resin particle by evaporating a solvent.

  Examples of the disperser used for dispersion of the emulsion by the melt emulsification method include a homogenizer, a homomixer, a pressure kneader, an extruder, and a media disperser.

  Examples of the aqueous medium include water such as distilled water and ion-exchanged water; alcohols; and the like, but preferably only water.

  Examples of the dispersant used in the emulsification step include water-soluble polymers such as polyvinyl alcohol, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, sodium polyacrylate, and sodium polymethacrylate; sodium dodecylbenzenesulfonate. Anionic surfactants such as sodium octadecyl sulfate, sodium oleate, sodium laurate, potassium stearate, cationic surfactants such as laurylamine acetate, stearylamine acetate, lauryltrimethylammonium chloride, lauryldimethylamine oxide, etc. Zwitterionic surfactant, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene Surfactants such as nonionic surfactants down alkylamines, and the like. Of these, anionic surfactants are used from the viewpoint of easy cleaning and environmental suitability.

  10-50 weight% is preferable and, as for content of the resin particle contained in the emulsified liquid in the said emulsification process, 20-40 weight% is more preferable. When the content is 10% by weight or more, the particle size distribution does not spread excessively. Moreover, if it is 50 weight% or less, it can stir without dispersion | variation and the colored particle | grains with a narrow particle size distribution and the uniform characteristic are obtained.

  The volume average particle diameter of the resin particles is preferably in the range of 0.08 to 0.8 μm, more preferably 0.09 to 0.6 μm, and still more preferably 0.10 to 0.5 μm. If it is 0.08 μm or more, the resin particles tend to aggregate. Moreover, if it is 0.8 micrometer or less, since the particle size distribution of a colored particle is hard to spread and precipitation of an emulsified particle is suppressed, the preservability of an emulsified particle dispersion improves.

Before entering the agglomeration step described below, it is preferable to prepare a dispersion liquid in which a colorant, a release agent, or the like, which is a colored particle component other than the binder resin, is dispersed.
In addition to the method of preparing a dispersion corresponding to each component such as a binder resin and a colorant, for example, when preparing an emulsion of a certain component, other components may be added to the solvent to add two or more The components may be emulsified at the same time so that the dispersed particles contain a plurality of components.

[Aggregation process]
In the aggregation process, the resin particle dispersion obtained in the emulsification process, a colorant dispersion, and the like are mixed to form a mixed liquid, which is heated at a temperature equal to or lower than the glass transition temperature of the binder resin for aggregation. It is preferable to form particles. The formation of the aggregated particles is preferably performed by making the pH of the mixed solution acidic while stirring. As pH, the range of 2-7 is preferable, the range of 2.2-6 is more preferable, and the range of 2.4-5 is still more preferable.

  It is also effective to use a flocculant when forming the agglomerated particles. As the flocculant, a surfactant having a polarity opposite to that of the surfactant used for the dispersant, an inorganic metal salt, and a divalent or higher metal complex are preferably used. The use of a metal complex is particularly preferred because the amount of surfactant used can be reduced and charging characteristics are improved.

  Examples of the inorganic metal salt include metal salts such as calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, and aluminum sulfate, and polyaluminum chloride, polyaluminum hydroxide, and calcium polysulfide. Examples thereof include inorganic metal salt polymers. Among these, an aluminum salt and a polymer thereof are particularly preferable. In order to obtain a narrower particle size distribution, the valence of the inorganic metal salt is bivalent than monovalent, trivalent than bivalent, trivalent than trivalent, and tetravalent than trivalent. Inorganic metal salt polymers are more suitable.

  Further, when the aggregated particles have a desired particle diameter, colored particles having a structure in which the surface of the core aggregated particles is coated with a binder resin can be prepared by additionally adding resin particles (resin emulsified particles). Good. In this case, the release agent and the crystalline polyester resin are less likely to be exposed on the surface of the colored particles, which is a preferable configuration from the viewpoint of chargeability and storage stability. In the case of additional addition, a flocculant may be added or pH adjustment may be performed before additional addition.

[Fusion process]
In the fusing step, the agglomeration is stopped by increasing the pH of the suspension of the aggregated particles to a range of 4 to 8 under the stirring conditions in accordance with the aggregation step, and the glass transition temperature is higher than the glass transition temperature of the binder resin. It is preferable to fuse the aggregated particles by heating at a temperature. An aqueous NaOH solution is preferred as the alkaline solution used to raise the pH. The aqueous NaOH solution has lower volatility and higher safety than other alkaline solutions such as an ammonia solution. In addition, compared with a divalent alkaline solution such as Ca (OH) ₂ , the solubility in water is small, the required amount of addition is small, and the ability to stop aggregation is excellent.

The heating time may be as long as fusion between particles is performed, and is preferably 0.5 to 10 hours. Cooling is performed after the aggregated particles are fused to obtain fused particles. Also, in the cooling process, the cooling rate is increased in the vicinity of the melting temperature of the release agent and binder resin (melting temperature ± 10 ° C range), so-called rapid cooling enables recrystallization of the release agent and binder resin. It may be suppressed to suppress surface exposure.
Through the above steps, colored particles are obtained as fused particles.

The colored particles used in the present embodiment are also produced by a kneading and pulverizing method.
In order to produce colored particles by the kneading and pulverization method, for example, a binder resin, a colorant, a release agent, and the like are melt-kneaded and dispersed using, for example, a pressure kneader, a roll mill, an extruder, etc. Further, there is used a method of pulverizing with a jet mill or the like and classifying with a classifier such as an air classifier to prepare colored particles having a target particle size.

(Career)
In the present embodiment, the carrier has a shape factor SF1 of 100 to 120 and a shape factor SF2 of 100 to 120. The carrier is preferably a carrier containing a core material in which a magnetic powder is contained in a resin, and more preferably a carrier having a resin coating layer on the surface of the core material (hereinafter also referred to as “resin-coated carrier”).
The core material is not particularly limited, and is a magnetic particle dispersion containing magnetic metal particles such as iron, steel, nickel and cobalt, or a magnetic oxide or magnetic powder (magnetic particles) such as ferrite and magnetite, and a binder resin. Examples include mold cores. As the core material in the present embodiment, a core material in which magnetic powder is dispersed in a binder resin is preferable because the specific gravity is light and the stress applied to the toner is small.

As said magnetic powder disperse | distributed in binder resin, the thing of the structure shown by Formula (1) is preferable.
(MO) _X (Fe ₂ O ₃ ) _Y (1)
In the formula (1), M represents at least one selected from the group consisting of Cu, Zn, Fe, Mg, Mn, Ca, Li, Ti, Ni, Sn, Sr, Al, Ba, Co, and Mo, X and Y represent mol ratios and satisfy the condition X + Y = 100.

As the magnetic powder dispersed in the binder resin, conventionally known magnetic powders can be used, and ferrite, magnetite, and maghematite are preferable. As the ferromagnetic magnetic particles, magnetite and maghematite are preferable. Other magnetic particles are preferably iron powder.
Examples of magnetic particles include iron oxides such as magnetite, γ-iron oxide, Mn—Zn ferrite, Ni—Zn ferrite, Mn—Mg ferrite, Li ferrite, and Cu—Zn ferrite, Among these, magnetite is preferable. The magnetic particles may be subjected to various surface treatments, and those subjected to surface treatment with a silane coupling agent, a titanium coupling agent, silicone oil, or the like are preferably used.

The volume average particle size of the magnetic powder is preferably from 0.01 to 1 μm, more preferably from 0.05 to 0.7 μm, from the viewpoint of surface smoothness and dispersion uniformity, and preferably from 0.1 to 0 More preferably, it is 6 μm.
The content of the magnetic particles in the core material is preferably 30 to 95% by weight, more preferably 45 to 90% by weight, and still more preferably 60 to 90% by weight in order to obtain a desired magnetic force.

  As the binder resin constituting the core material, polyolefin resins such as polyethylene and polypropylene; polystyrene, acrylic resin, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether, polyvinyl ketone, and the like Polyvinyl resins and polyvinylidene resins; vinyl chloride-vinyl acetate copolymers; styrene-acrylic acid copolymers; straight silicone resins composed of organosiloxane bonds or modified products thereof; polytetrafluoroethylene, polyvinyl fluoride, polyfluoride Fluorine resins such as vinylidene and polychlorotrifluoroethylene; silicone resin; polyester; polyurethane; polycarbonate; phenol resin; Formaldehyde resins, melamine resins, benzoguanamine resins, urea resins, amino resins such as polyamide resins, epoxy resins and the like. These may be used individually by 1 type and may use 2 or more types together. In this embodiment, a phenol resin is preferable.

  Further, the magnetic particle-dispersed core material may further contain other components. Examples of other components include a charge control agent and fluorine-containing particles.

As the resin (matrix resin) constituting the resin coating layer of the resin-coated carrier, a general resin can be used. For example, polyolefin resins such as polyethylene and polypropylene; polystyrene and acrylic resins, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether, polyvinyl ketone, and other polyvinyl and polyvinylidene resins; Vinyl-vinyl acetate copolymer; Styrene-acrylic acid copolymer; Straight silicone resin composed of organosiloxane bond or modified product thereof; Fluorine such as polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, polychlorotrifluoroethylene, etc. Polyester; Polyurethane; Polycarbonate; Phenol resin; Urea-formaldehyde resin, melamine resin, benzoguanamine resin, resin A resin, amino resins such as polyamide resins; silicone resins; epoxy resins.
These may be used individually by 1 type and may use 2 or more types together.

In particular, for contamination of the toner component, a low surface energy resin such as a fluororesin or a silicone resin is preferably used as the resin coating layer, and more preferably coated with the fluororesin.
Examples of fluororesins include fluoropolyolefins, fluoroalkyl (meth) acrylate polymers and / or copolymers, vinylidene fluoride polymers and / or copolymers, and mixtures thereof, and form fluororesins. Fluorine-containing monomers such as tetrafluoropropyl methacrylate, pentafluoromethacrylate, octafluoropentyl methacrylate, perfluorooctylethyl methacrylate, trifluoroethyl methacrylate, etc. Is preferred. However, it is not limited to these.
As a compounding quantity of the monomer containing a fluorine, it is preferable to mix | blend in the range of 0.1-50.0 weight% with respect to all the monomers which comprise a resin coating layer, 0.5-40 The range is more preferably 0.0% by weight, and still more preferably 1.0 to 30.0% by weight. If it is in the above range, the contamination resistance can be sufficiently secured, the adhesiveness of the resin coating layer to the core material is sufficient, and the charging property is also excellent.

As the resin coating layer, one containing conductive particles (hereinafter also referred to as “conductive particles”) in the resin is used. Here, the conductivity means that the volume resistivity is less than 10 ⁷ Ω · cm. Examples of the conductive particles include metal particles such as gold, silver, and copper; carbon black particles; particles of metal oxides such as titanium oxide and zinc oxide; titanium oxide, zinc oxide, barium sulfate, aluminum borate, and potassium titanate. Examples thereof include particles whose surface such as powder is covered with tin oxide, carbon black, metal, and the like. These may be used individually by 1 type and may use 2 or more types together. Among these, carbon black particles are desirable.
The type of carbon black is not particularly limited, but carbon black having a DBP oil absorption of 50 to 250 ml / 100 g is desirable.

  The method for producing the carrier is not particularly limited as long as the carrier having the above structure is formed. For example, the carrier is prepared by first mixing a resin-dissolved layer-forming solution in which a resin-dissolved solution is stirred and dispersed using a disperser (for example, Ultra Turrax T50) and a carrier core material in a kneader coater. It is then produced by removing the solvent.

  The volume average particle size of the core material of the carrier is preferably 10 to 500 μm and more preferably 30 to 100 μm from the viewpoint of improving the image quality.

The shape factor SF1 of the carrier is 100 to 120, preferably 100 to 119, and more preferably 100 to 118, from the viewpoint of improving the fluidity of the developer. By improving the fluidity of the developer, the amount of developer on the developer holding member is stabilized, and the image density and image quality are stabilized not only in the initial stage but also in the case where time has elapsed due to continuous operation. Further, since the bulk density of the developer is high, the toner density control in the developer by the magnetization sensor is improved, and the image density and image quality are further stabilized.
Here, the shape factor SF1 is obtained by the following equation.
SF1 = (ML ² / A) × (π / 4) × 100
In the formula, ML represents the absolute maximum length of the carrier, and A represents the projected area of the carrier.

The carrier shape factor SF2 is 100 to 120, preferably 100 to 119, and more preferably 100 to 118, from the viewpoint of improving the fluidity of the developer. By improving the fluidity of the developer, the amount of developer on the developer holding member is stabilized, and the image density and image quality are stabilized not only in the initial stage but also in the case where time elapses due to continuous operation. Further, since the bulk density of the developer is high, the toner density control in the developer by the magnetization sensor is improved, and the image density and image quality are further stabilized. An excellent effect is obtained by the combination with the shape factor SF1.
Here, the shape factor SF2 is obtained by the following equation.
SF2 = (L ² / S) × {100 / (4π)}
In the equation, L represents the peripheral length of the projected image of the carrier, and S represents the projected area of the carrier.

  The specific gravity of the carrier is preferably 3.2 to 4.2 and more preferably 3.4 to 4.0 because it reduces the mechanical external force on the toner.

  As a mixing ratio (weight ratio) of the electrostatic image developing toner and the carrier in the electrostatic image developer of the present embodiment, toner: carrier = from the viewpoint of obtaining a stable density and good image quality without fogging. 1: 100-30: 100 is preferable and 3: 100-20: 100 is more preferable.

(Resin particles)
In the present embodiment, the resin particles exist in a state independent of the toner, and are charged with a polarity opposite to that of the inorganic particles by friction with the carrier.
The resin particles may be any one that is charged with a polarity opposite to that of the inorganic particles externally added to the toner, but the inorganic particles externally added to the toner are generally negatively charged. Thus, when the inorganic particles are negatively charged, the resin particles need to be positively charged.

  In the present embodiment, the volume average particle size of the resin particles is preferably larger than the volume average particle size of the inorganic particles, more preferably 2 times or more of the volume average particle size of the inorganic particles, and 3 times or more. More preferably it is. If the volume average particle size of the resin particles is larger than the volume average particle size of the inorganic particles, the inorganic particles are likely to be physically fixed on the surface of the resin particles due to the force when the developer is agitated. Together, the trapping efficiency of inorganic particles is improved.

Specifically, the volume average particle diameter of the resin particles is preferably 200 to 4,000 nm, and more preferably 220 to 3,000 nm. When it is 200 nm or more, the ability to capture free inorganic particles increases, and deformation due to mechanical stress and adhesion to the toner surface are suppressed. Moreover, the fall of the total surface area of a resin particle is avoided as it is 4,000 nm or less, and the capability to capture | acquire the liberated inorganic particle becomes sufficient.
In consideration of the measurement accuracy by the measuring device, when the diameter of the particle to be measured is 2 μm or more, the volume average particle diameter of the resin particle is, for example, Coulter Multisizer II (manufactured by Beckman Coulter, Inc.) When the particle diameter to be measured is less than 2 μm, the measurement is performed using a laser diffraction particle size distribution measuring device (LS13 320: manufactured by Beckman Coulter, Inc.).

In this embodiment, the average circularity of the resin particles is preferably 0.974 or more, and more preferably 0.976 or more. When it is 0.974 or more, the mobility of the resin particles on the carrier surface becomes excellent, and the inorganic particles are captured with high efficiency by the resin particles.
Here, the average circularity is a value obtained by performing image analysis on a certain number of resin particles, obtaining the circularity according to the following equation for each photographed resin particle, and averaging them.
Circularity = circle equivalent diameter perimeter / perimeter = [2 × (A × π) ^1/2 ] / PM
(In the above formula, A represents the projected area and PM represents the perimeter.)
The average circularity of the resin particles is determined by measuring the circularity of 5,000 particles using a flow particle image analyzer FPIA-3000 (manufactured by Sysmex Corporation). The average circularity of the resin particles is preferably obtained.

Examples of the resin particles include particles obtained from soap-free emulsion polymerization, suspension polymerization, and dispersion polymerization, homopolymers or copolymers of methacrylic acid esters, homopolymers or copolymers of acrylic acid esters, and the like. And particles made of a polycondensation resin such as a silicone resin, a benzoguanamine resin, and a nylon resin, and particles made of a thermosetting resin such as a urea resin and a melamine resin.
Among these, as the resin particles, particles made of polymethyl methacrylate (PMMA) are preferable from the viewpoint described below, and particles made of PMMA obtained by soap-free emulsion polymerization are more preferable.
PMMA has high positive chargeability and excellent impact resistance. Moreover, since it is highly transparent, even if it is included in the image, it does not affect the hue. Moreover, since it is easy to produce as latex, it is easy to produce spherical particles and the cost is low. Moreover, although the particle | grains which consist of PMMA have high plus electrification property, compared with the particle | grains which consist of urea resin and melamine resin which are bridge | crosslinking particles, an inorganic particle is easy to adhere to the surface. Furthermore, PMMA has been conventionally used as a photoconductor cleaning aid, and its effect can be expected.
Further, since the particles produced by soap-free emulsion polymerization do not have a surfactant on the particle surface, they do not easily contaminate the carrier, the toner surface, etc., and do not change the charging characteristics.

  In this embodiment, the addition amount of the resin particles is preferably 0.1 to 5% by weight, and more preferably 0.15 to 4.5% by weight with respect to the total weight of the colored particles. When the content is 0.1% by weight or more, the inorganic particles released by the resin particles are sufficiently captured. On the other hand, when the content is 5% by weight or less, adverse effects on the charging characteristics of the toner are avoided.

(2) Image Forming Apparatus and Image Forming Method Next, the image forming apparatus and the image forming method of the present embodiment using the electrostatic charge image developer of the present embodiment will be described.
The image forming apparatus according to the present embodiment includes at least a photosensitive member, a charging unit that uniformly charges the photosensitive member, and electrostatic latent image formation that exposes the charged photosensitive member to form an electrostatic latent image. A developing means for developing the electrostatic latent image formed on the photosensitive member as a toner image by the electrostatic charge image developer of the present embodiment; and the toner image formed on the photosensitive member to be transferred. The image forming apparatus includes a transfer unit that transfers onto a body, and a fixing unit that fixes a toner image transferred onto the transfer target. The developing means includes a developer holding body for supplying the electrostatic charge image developer to the photoreceptor, and the resin particles discharged from the developing means are disposed below the developer holding body in the gravity direction. It is preferable to further have a storage means for storing.
Further, the image forming method of the present embodiment includes a charging step for uniformly charging a photoconductor, an electrostatic latent image forming step for exposing the charged photoconductor to form an electrostatic latent image, and the photosensitivity. A developing process for developing the electrostatic latent image formed on the body as a toner image by the electrostatic charge image developer of the present embodiment, and transferring the toner image formed on the photoreceptor onto the transfer target. A transfer step; and a fixing step of fixing the toner image transferred onto the transfer target. The image forming method of the present embodiment preferably further includes an accumulation step for accumulating the resin particles discharged in the development step.

In this image forming apparatus, for example, the part including the developing unit may have a cartridge structure (process cartridge) that can be attached to and detached from the image forming apparatus main body. As the process cartridge, a developer holding body is used. The process cartridge of the present embodiment is preferably used that includes at least the electrostatic charge image developer of the present embodiment.
Hereinafter, although an example of the image forming apparatus of this embodiment is shown, it is not necessarily limited to this. In addition, the main part shown to a figure is demonstrated and the description is abbreviate | omitted about others.

  FIG. 1 is a schematic configuration diagram showing a quadruple tandem color image forming apparatus. The image forming apparatus shown in FIG. 1 is a first to first electrophotographic method that outputs yellow (Y), magenta (M), cyan (C), and black (K) images based on color-separated image data. Fourth image forming units 10Y, 10M, 10C, and 10K (image forming means) are provided. These image forming units (hereinafter sometimes simply referred to as “units”) 10Y, 10M, 10C, and 10K are juxtaposed in a horizontal direction separated from each other by a predetermined distance. The units 10Y, 10M, 10C, and 10K may be process cartridges that are detachable from the main body of the image forming apparatus.

Above each of the units 10Y, 10M, 10C, and 10K, an intermediate transfer belt 20 as an intermediate transfer member is extended through each unit. The intermediate transfer belt 20 is provided by being wound around a driving roller 22 and a support roller 24 that are in contact with the inner surface of the intermediate transfer belt 20 that are arranged away from each other in the left to right direction in the drawing, and the first unit 10Y to the fourth unit. It is designed to travel in the direction toward 10K. The support roller 24 is applied with a force in a direction away from the driving roller 22 by a spring or the like (not shown), and tension is applied to the intermediate transfer belt 20 wound around the both. Further, an intermediate transfer member cleaning device 30 is provided on the side of the image carrier of the intermediate transfer belt 20 so as to face the driving roller 22.
Each of the units 10Y, 10M, 10C, and 10K has developing units (developing means) 4Y, 4M, 4C, and 4K, and toner or developer cartridges 8Y, 8M, 8C, and 8K, yellow, magenta, Four color toners or developers of cyan and black can be supplied.

  Since the first to fourth units 10Y, 10M, 10C, and 10K described above have the same configuration, here, the first image that forms the yellow image disposed on the upstream side in the intermediate transfer belt traveling direction is formed. The unit 10Y will be described as a representative. It should be noted that reference numerals with magenta (M), cyan (C), and black (K) are attached to the same parts as those of the first unit 10Y instead of yellow (Y). Description of the units 10M, 10C, and 10K will be omitted.

The first unit 10Y has a photoreceptor 1Y that functions as an image carrier (photoreceptor). Around the photoreceptor 1Y, there is a charging roller (charging device, charging means) 2Y for charging the surface of the photoreceptor 1Y to a predetermined potential, and a laser beam 3Y based on an image signal obtained by color-separating the charged surface. An exposure device (electrostatic latent image forming unit) 3 that forms an electrostatic image by exposure, a developing device (developing unit) 4Y that develops the electrostatic image by supplying toner charged to the electrostatic image, and a developed toner image A primary transfer roller (primary transfer unit) 5Y for transferring the toner onto the intermediate transfer belt 20 and a photoconductor cleaning device (cleaning unit) 6Y for removing toner remaining on the surface of the photoconductor 1Y after the primary transfer are arranged in this order. Has been.
The primary transfer roller 5Y is disposed inside the intermediate transfer belt 20 and is provided at a position facing the photoreceptor 1Y. Further, a bias power source (not shown) for applying a primary transfer bias is connected to each of the primary transfer rollers 5Y, 5M, 5C, and 5K. Each bias power source varies the transfer bias applied to each primary transfer roller under the control of a control unit (not shown).

Hereinafter, an operation of forming a yellow image in the first unit 10Y will be described. First, prior to the operation, the surface of the photoreceptor 1Y is charged to a potential of about −600V to −800V by the charging roller 2Y.
The photoreceptor 1Y is formed by laminating a photosensitive layer on a conductive substrate (volume resistivity at 20 ° C .: 1 × 10 ⁻⁶ Ωcm or less). This photosensitive layer usually has a high resistance (resistance of a general resin level), but when the laser beam 3Y is irradiated from the exposure device (electrostatic latent image forming means) 3, the portion irradiated with the laser beam 3Y is irradiated. It has the property that the specific resistance changes. Therefore, a laser beam 3Y is output to the surface of the charged photoreceptor 1Y via the exposure device 3 in accordance with yellow image data sent from a control unit (not shown). The laser beam 3Y is applied to the photosensitive layer on the surface of the photoreceptor 1Y, whereby an electrostatic charge image of a yellow print pattern is formed on the surface of the photoreceptor 1Y.

The electrostatic charge image (electrostatic latent image) is an image formed on the surface of the photoreceptor 1Y by charging, and the specific resistance of the irradiated portion of the photosensitive layer is lowered by the laser beam 3Y, so that the surface of the photoreceptor 1Y On the other hand, this is a so-called negative latent image formed by the flow of the charged electric charge while the electric charge in the portion not irradiated with the laser beam 3Y remains.
The electrostatic charge image formed on the photoreceptor 1Y in this way is rotated to a predetermined development position as the photoreceptor 1Y travels. At this development position, the electrostatic image on the photoreceptor 1Y is converted into a visible image (developed image, toner image) by the developing device 4Y.

  In the developing device 4Y, for example, an electrostatic charge image developer according to the present embodiment including at least yellow toner and a carrier is accommodated. The yellow toner is triboelectrically charged by being agitated inside the developing device 4Y, and has a charge of the same polarity (negative polarity) as the charged electric charge on the photoreceptor 1Y, and a developer roll (developer holding body). Is held on. As the surface of the photoreceptor 1Y passes through the developing device 4Y, yellow toner adheres electrostatically to the latent image portion on the surface of the photoreceptor 1Y, and the latent image is developed with the yellow toner. . The photoreceptor 1Y on which the yellow toner image is formed continues to run at a predetermined speed, and the toner image developed on the photoreceptor 1Y is conveyed to a predetermined primary transfer position.

  When the yellow toner image on the photoreceptor 1Y is conveyed to the primary transfer, a primary transfer bias is applied to the primary transfer roller 5Y, and an electrostatic force from the photoreceptor 1Y toward the primary transfer roller 5Y acts on the toner image. Then, the toner image on the photoreceptor 1Y is transferred onto the intermediate transfer belt 20. The transfer bias applied at this time is a (+) polarity opposite to the polarity (−) of the toner. For example, in the first unit 10Y, it is controlled to about +10 μA by a control unit (not shown). On the other hand, the toner remaining on the photoreceptor 1Y is removed and collected by the cleaning device 6Y.

Further, the primary transfer bias applied to the primary transfer rollers 5M, 5C, and 5K after the second unit 10M is also controlled according to the first unit.
Thus, the intermediate transfer belt 20 onto which the yellow toner image has been transferred by the first unit 10Y is sequentially conveyed through the second to fourth units 10M, 10C, and 10K, and the toner images of the respective colors are superimposed and transferred in a multiple manner. The

  The intermediate transfer belt 20 onto which the four color toner images have been transferred through the first to fourth units is arranged on the image transfer surface side of the intermediate transfer belt 20, the support roller 24 in contact with the inner surface of the intermediate transfer belt 20. The secondary transfer roller (secondary transfer means) 26 is connected to a secondary transfer portion. On the other hand, the recording paper (transfer object) P is fed at a predetermined timing to the gap where the secondary transfer roller 26 and the intermediate transfer belt 20 are pressed against each other via the supply mechanism, and the secondary transfer bias is supported. Applied to the roller 24. The transfer bias applied at this time is a (−) polarity that is the same polarity as the polarity (−) of the toner, and an electrostatic force from the intermediate transfer belt 20 toward the recording paper P is applied to the toner image, and the transfer bias is applied to the intermediate transfer belt 20. The toner image is transferred onto the recording paper P. The secondary transfer bias at this time is determined according to the resistance detected by a resistance detection means (not shown) for detecting the resistance of the secondary transfer portion, and is voltage-controlled.

  Thereafter, the recording paper P is fed to the pressure contact portion (nip portion) of the pair of fixing rolls in the fixing device (roll-type fixing means) 28, the toner image is heated, and the color-superposed toner image is melted to record the recording paper. Fixed onto P. From the viewpoint of suppressing power consumption, the fixing temperature is preferably 145 ° C. or lower, and more preferably 100 to 140 ° C.

Examples of the transfer target to which the toner image is transferred include plain paper and OHP sheet used for electrophotographic copying machines, printers, and the like.
In order to further improve the smoothness of the image surface after fixing, it is preferable that the surface of the transfer target is as smooth as possible. For example, a coated paper in which the surface of plain paper is coated with a resin, etc. Art paper or the like is preferably used.

The recording paper P on which the color image has been fixed is carried out toward the discharge unit, and a series of color image forming operations is completed.
The image forming apparatus exemplified above is configured to transfer the toner image onto the recording paper P via the intermediate transfer belt 20, but the present invention is not limited to this configuration, and the toner image is directly transferred from the photoconductor. It may be a structure that is transferred to a recording sheet.

(3) Process Cartridge, Toner Cartridge FIG. 2 is a schematic configuration diagram showing a preferred example embodiment of a process cartridge containing an electrostatic charge image developer according to this embodiment. In the process cartridge 200, the charging roller 108, the developing device 111, the photoconductor cleaning device 113, the opening 118 for exposure, and the opening 117 for static elimination exposure are combined using the mounting rail 116 together with the photoconductor 107. , And integrated. In FIG. 2, reference numeral 300 denotes a transfer target.
The process cartridge 200 is detachable from an image forming apparatus main body including a transfer device 112, a fixing device 115, and other components (not shown). It forms a forming apparatus.

The process cartridge 200 shown in FIG. 2 includes a charging device 108, a developing device 111, a photoconductor cleaning device 113, an opening 118 for exposure, and an opening 117 for static elimination exposure. It is possible to combine them selectively. In the process cartridge of this embodiment, in addition to the photosensitive member 107, the charging device 108, the developing device 111, the photosensitive member cleaning device (cleaning means) 113, the opening 118 for exposure, and the opening for static elimination exposure. At least one selected from the group consisting of the unit 117.
A developing machine (developing unit) 111 in which an electrostatic charge image developer according to the present embodiment is accommodated has a developer roll (developer holder) 120 that supplies the electrostatic charge image developer to the photosensitive member. Further, the developing device 111 preferably has a storage unit 121 that stores the resin particles discharged from the developing device 111 below the developer roll 120 in the direction of gravity. Examples of the storage unit 121 include a tray.
The resin particles that have captured the inorganic particles released from the toner are discharged by the centrifugal force of the developer roll 120. The discharged resin particles fall by gravity and are accumulated in the accumulation means 121 disposed on the lower side of the developer roll 120 in the gravity direction. In this way, contamination in the image forming apparatus due to the resin particles capturing the inorganic particles is prevented.

  Next, the developer cartridge according to this embodiment will be described. The developer cartridge according to the present embodiment is detachably attached to the image forming apparatus, and includes at least a developer cartridge that stores a developer to be supplied to a developing unit provided in the image forming apparatus. The developer is the electrostatic charge image developer according to the exemplary embodiment described above.

  Therefore, in the image forming apparatus having a configuration in which the developer cartridge can be attached and detached, the electrostatic charge image development according to the present embodiment is performed by using the developer cartridge containing the electrostatic charge image developer according to the present embodiment. The agent is supplied to the developing machine.

  The image forming apparatus shown in FIG. 1 is an image forming apparatus having a configuration in which the developer cartridges 8Y, 8M, 8C, and 8K can be attached and detached. A developer cartridge corresponding to (color) is connected to a developer supply pipe (not shown). Further, when the developer stored in the developer cartridge becomes small, the developer cartridge is replaced.

  Hereinafter, although an Example and a comparative example are given and this embodiment is described in detail in detail, this embodiment is not limited to the following examples. Unless otherwise specified, “parts” and “%” represent “parts by weight” and “% by weight”.

I. Preparation of toner Synthesis of resin for binder resin (synthesis of amorphous polyester resin (1))
In a heat-dried two-necked flask, 90 mol parts of polyoxyethylene (2,0) -2,2-bis (4-hydroxyphenyl) propane, 10 mol parts of ethylene glycol, 80 mol parts of terephthalic acid, and isophthalic acid 20 mol part as a raw material, dibutyltin oxide is added as a catalyst, nitrogen gas is introduced into the container and heated in an inert atmosphere, and then subjected to a copolycondensation reaction at 150 to 230 ° C. for about 12 hours, The pressure was gradually reduced at 210 to 250 ° C. to synthesize amorphous polyester resin (1).
The weight average molecular weight (Mw) of the amorphous polyester resin (1) was 23,200. The acid value of the amorphous polyester resin (1) was 14.2 mgKOH / g. The glass transition temperature (Tg) of the amorphous polyester resin (1) was 62 ° C.

(Synthesis of amorphous polyester resin (2))
The amorphous polyester resin (2) was synthesized in the same manner as the amorphous polyester resin (1) except that the condensation polymerization reaction time was about 11 hours.
The weight average molecular weight (Mw) of the amorphous polyester resin (2) was 18,400. The acid value of the amorphous polyester resin (2) was 17.4 mgKOH / g. The glass transition temperature (Tg) was 60 ° C.

2. Preparation of amorphous binder resin dispersion (Preparation of amorphous polyester resin dispersion (1))
Amorphous polyester resin (1) 100 parts Solvent (1): Methyl ethyl ketone 40 parts Solvent (2): 2-propanol 25 parts Basic compound: 10% by weight aqueous ammonia solution 3.5 parts Distilled water (dried nitrogen before dropping) 400 parts that were subjected to deoxygenation by bubbling under reduced pressure): 400 parts Amorphous polyester resin (1), solvent (1) and solvent (2) were put into a container capable of temperature adjustment and nitrogen substitution, and resin (1 ), And a basic compound was added, and the mixture was stirred at 150 rpm using a three-one motor (manufactured by Shinto Kagaku Co., Ltd.) with an anchor blade at 41 ° C. for 10 minutes to obtain a resin-containing solution. It was.
Next, the container was purged with dry nitrogen, the temperature was set to 41 ° C., and phase-inversion emulsification was performed by adding distilled water dropwise at a rate of 1 part / minute while stirring the resin-containing liquid at 180 rpm.
After completion of dropping, the solvent (1) and the solvent (2) were removed by carrying out dry nitrogen bubbling at 25 ° C. for 24 hours while stirring at 70 rpm to obtain a resin dispersion (1). The volume average particle diameter of the resin particles (1) in the obtained resin dispersion (1) was 210 nm.

(Preparation of amorphous polyester resin dispersion (2))
A resin dispersion (2) was obtained in the same manner as the resin dispersion (1) except that the amorphous polyester resin (1) was changed to the amorphous polyester resin (2). The volume average particle diameter of the resin particles (2) in the obtained resin dispersion (2) was 160 nm.

3. Production of inorganic particles (Production of SiO ₂ particles (1))
The silica sol obtained by the sol-gel method was treated with HMDS (hexamethyldisilazane), and dried and crushed to obtain SiO ₂ particles (1) having a volume average particle diameter of 140 nm.

(Preparation of SiO ₂ particles (2))
Silica sol obtained by the sol-gel method was treated with HMDS (hexamethyldisilazane), and dried and crushed to obtain SiO ₂ particles (2) having a volume average particle diameter of 520 nm.

(Preparation of SiO ₂ particles (3))
Silica sol obtained by the sol-gel method was treated with HMDS (hexamethyldisilazane), and dried and ground to obtain SiO ₂ particles (3) having a volume average particle diameter of 70 nm.

(Production of titanium oxide external additive)
A rutile type titanium oxide (MT-150A, Teica) having a volume average particle size of 15 nm, which was washed with water in a methanol-water (95: 5) mixed solvent in which 1.0 part of methyltrimethoxysilane was dissolved to reduce the amount of water-soluble components. 10 parts of powder was added and ultrasonically dispersed. Next, after evaporating methanol and the like in the dispersion with an evaporator, drying, heat treatment with a dryer set at 120 ° C., grinding with a mortar, and surface treatment with methyltrimethoxysilane, the titanium oxide external additive Got.

4). Preparation of release agent dispersion (release agent dispersion)
・ 50 parts of paraffin wax (Nippon Seiwa Co., Ltd., HNP-9, melting point: 75 ° C.) 0.5 part of anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd., Neogen RK) : 200 parts or more were mixed, heated to 95 ° C., and dispersed using a homogenizer (manufactured by IKA, Ultra Turrax T50). Thereafter, the mixture was dispersed with a Manton Gorin high-pressure homogenizer (manufactured by Gorin Co., Ltd.) to prepare a release agent dispersion (solid content concentration: 20%) in which the release agent was dispersed. The volume average particle diameter of the release agent was 0.23 μm.

5. Preparation of colorant dispersion (colorant dispersion)
Cyan pigment (Daiichi Seika Co., Ltd., Pigment Blue 15: 3 (copper phthalocyanine) 1,000 parts Anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd., Neogen R) 15 parts 9,000 parts or more are mixed, dissolved, and dispersed for 1 hour using a high-pressure impact disperser Ultimateizer (manufactured by Sugino Machine Co., Ltd., HJP30006) to disperse a colorant (cyan pigment). The colorant (cyan pigment) in the colorant dispersion had a volume average particle size of 0.16 μm and a solid content concentration of 20%.

6). Preparation of toner (preparation of toner (1))
Amorphous polyester resin dispersion liquid (1) 267 parts Colorant dispersion liquid 25 parts Release agent dispersion liquid 40 parts Anionic surfactant (Taika Power / manufactured by Teika Co., Ltd.) 2.0 parts -Mixing process-
The raw material was placed in a cylindrical stainless steel container, and the homogenizer (Ultra Turrax T50, manufactured by IKA) was used. The homogenizer was rotated at 4,000 rpm and dispersed and mixed for 10 minutes while applying a shearing force. Next, 2.0 parts of a 10% nitric acid aqueous solution of polyaluminum chloride (PAC) as a flocculant (the content of nitric acid is 0.05N) is gradually dropped, and the homogenizer is rotated at 5,000 rpm for 15 minutes. And mixed to obtain a raw material dispersion.

-Aggregation process-
Thereafter, the raw material dispersion was transferred to a polymerization kettle equipped with a stirrer and a thermometer and started to be heated with a mantle heater to promote the growth of aggregated particles at 42 ° C. At this time, the pH of the raw material dispersion was adjusted to a range of 3.2 or more and 3.8 or less using 0.3N nitric acid or 1N sodium hydroxide aqueous solution. The raw material dispersion was kept in the above pH range and allowed to stand for about 2 hours to form aggregated particles. The volume average particle diameter of the aggregated particles was 5.4 μm.

-Fusion process-
Next, 100 parts of the amorphous polyester resin dispersion (1) was additionally added to the raw material dispersion, and the resin particles of the amorphous polyester resin (1) were adhered to the surface of the aggregated particles. Further, the temperature of the raw material dispersion was raised to 44 ° C., and aggregated particles were prepared while confirming the size and form of the particles using an optical microscope and Multisizer II. Thereafter, in order to fuse the aggregated particles, an aqueous NaOH solution was added dropwise to the raw material dispersion to adjust the pH to 7.5, and then the raw material dispersion was heated to 95 ° C. Thereafter, the raw material dispersion was allowed to stand for 3 hours to fuse the aggregated particles. After confirming that the aggregated particles were fused with an optical microscope, the colored particle dispersion was cooled at a temperature lowering rate of 1.0 ° C./min.

-Washing process-
Next, the colored particle dispersion was filtered, and the colored particles after solid-liquid separation were dispersed in ion-exchanged water at 30 ° C. that is 20 times the solid content of the colored particles, and filtered by stirring for 20 minutes. . This process was repeated 5 times, and it was confirmed that the filtrate had a conductivity of 25 μS. The colored particles were filtered and dried with a freeze dryer to obtain colored particles (1).

-Dry external addition-
To 100 parts of the colored particles (1), 1.4% of SiO ₂ particles (1) and 1.2% of the prepared titanium oxide external additive are added as external additives and mixed for 5 minutes with a Henschel mixer. did. Furthermore, the toner (1) was obtained by passing through an ultrasonic vibration sieve (45 μm / Dalton).

(Production of Toner (2))
A toner (2) was produced in the same manner as the toner (1) except that the amorphous polyester resin dispersion (1) was changed to the amorphous polyester resin dispersion (2).

(Production of Toner (3))
Except for changing SiO ₂ particles (1) to the SiO ₂ particles (2), to thereby produce toner (3) In the same manner as Toner (1).

(Production of Toner (4))
A toner (4) was produced in the same manner as the toner (1) except that the SiO ₂ particles (1) were changed to SiO ₂ particles (3).

II. Production of electrostatic image developer 1. Production of resin particles (Production of resin particles (1))
To a 3 L four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a separatory funnel, 2,000 g of ion-exchanged water and 200 g of methyl methacrylate were added and stirred. Next, the mixture was heated to 78 ° C., and 100 g of 1% potassium persulfate (manufactured by Wako Pure Chemical Industries, Ltd.) solution was added into the flask through a separatory funnel, and the reaction was carried out for 7 hours. The particle diameter of the resin particles thus obtained was determined by a light scattering method (LPA3000 / 3100 manufactured by Otsuka Electronics Co., Ltd.), and the volume average particle diameter was 400 nm. The resin particles were subjected to purification treatment by ultra membrane filtration (UF module ACV-3050 manufactured by Asahi Kasei Co., Ltd.) until the electric conductivity of the aqueous phase reached 50 μS to obtain a resin particle dispersion (1). Subsequently, after evaporating water with a rotary evaporator, it was dried overnight in a vacuum dryer at 50 ° C. Thereafter, the resin particles were pulverized and sieved to primary particles in a mortar. In this way, resin particles (1) made of polymethyl methacrylate were prepared. The resin particles (1) were subjected to image analysis by SEM observation, and the average circularity was calculated. The average circularity of the resin particles (1) was 0.990.

(Preparation of resin particles (2))
Resin particles (2) were obtained in the same manner as the resin particles (1) except that the reaction time and the stirring speed were adjusted. The volume average particle diameter of the resin particles (2) is 3,600 nm, and the average circularity is 0.986.

(Preparation of resin particles (3))
Resin particles (3) were obtained in the same manner as the resin particles (1) except that the reaction time and the stirring speed were adjusted. The volume average particle diameter of the resin particles (3) is 4,400 nm, and the average circularity is 0.986.

(Preparation of resin particles (4))
Resin particles (4) were obtained in the same manner as the resin particles (1) except that the reaction time and the stirring speed were adjusted. The volume average particle diameter of the resin particles (4) is 180 nm, and the average circularity is 0.991.

(Preparation of resin particles (5))
A magnesium sulfate aqueous solution was dropped into the dispersion of the resin particles (4) to aggregate the resin particles (4), and then the temperature was raised to 85 ° C. When the particle size was measured after cooling, the volume average particle size was 580 nm. Thereafter, after ultrafiltration, resin particles (5) were obtained in the same manner as resin particles (4). The average circularity of the resin particles (5) was 0.968.

2. Preparation of carrier (preparation of carrier (1)) ... Polymerization carrier Into a Henschel mixer, 500 parts of spherical magnetite particle powder having a volume average particle diameter of 0.55 µm was added and stirred sufficiently, and then titanate coupling agent 5 0.0 part was added, the temperature was raised to about 100 ° C., and the mixture was stirred for 30 minutes to obtain spherical magnetite particles coated with a titanate coupling agent.
Subsequently, 6.25 parts of phenol, 9.25 parts of 35% formalin, 500 parts of the spherical magnetite particles, 6.25 parts of 25% aqueous ammonia, and 425 parts of water were mixed and stirred in a four-necked flask. Next, the temperature is raised to 85 ° C. over 60 minutes while stirring, and after reacting at the same temperature for 120 minutes, the mixture is cooled to 25 ° C., 500 parts of water is added, the supernatant is removed, and the precipitate is removed. Washed with water. This was dried at 150 ° C. or higher and 180 ° C. or lower under reduced pressure to obtain spherical polymer core particles having a volume average particle diameter of 35 μm.

Next, a resin coating layer was formed on the surface of the core material by the following method.
200 parts of toluene and 30 parts of a styrene-methyl methacrylate copolymer (component ratio 30:70, weight average molecular weight 210,000) were stirred with a stirrer for 60 minutes to obtain a resin coating solution. 100 parts of the resin coating solution and 1.57 parts of carbon black (Regal 330: manufactured by Cabot Corporation) were stirred for 10 minutes at 5,000 rpm using a homogenizer (manufactured by IKA: Ultra Tarrax) to prepare a dispersion.
After 1,000 parts of the core material particles and 61.3 parts of the above dispersion were put into a vacuum degassing type kneader coater and stirred at 40 rpm for 30 minutes while maintaining 60 ° C., the temperature was further reduced to 70 ° C. and toluene was reduced. Distilled, degassed and dried. Furthermore, carrier (1) was prepared by passing through a mesh having an opening of 75 μm. The volume average particle diameter of the carrier (1) was 37 μm.
The obtained carrier (1) was observed using a scanning electron microscope (manufactured by Hitachi, Ltd .: S-4100) to take an image, and this image was taken as an image analyzer (for example, LUZEXIII, Nireco Corporation). SF1 and SF2 were calculated for each particle of 100 or more particles, and the average value was obtained as SF1 and SF2 of the carrier (1). The SF1 of carrier (1) was 106, and SF2 was 104. The specific gravity of the carrier was 3.6.

(Carrier (2) of Preparation) ... ferrite carrier Fe ₂ O ₃ to 73 parts, MnO ₂ to 23 parts, Mg and (OH) ₂ 4 parts were mixed, 25 hours mixing / grinding to a wet ball mill spray After granulating and drying with a drier, preliminary baking 1 was performed at 800 ° C. for 7 hours using a rotary kiln to obtain a temporary baking product 1.
The obtained calcined product 1 was pulverized with a wet ball mill for 7 hours to have a volume average particle diameter of 1.8 μm, further granulated and dried with a spray dryer, and then 900 ° C. for 6 hours with a rotary kiln. Was calcined 2 to obtain a calcined product 2.
The obtained calcined product 2 was pulverized with a wet ball mill for 5 hours to have an average particle size of 5.2 μm, and further granulated and dried with a spray dryer, and then at 1,000 ° C. using an electric furnace. The main baking was performed for 12 hours. After the main firing, Mn—Mg ferrite core material particles having a volume average particle diameter of 36.6 μm were obtained through a crushing step and a classification step.

Next, a resin coating layer was formed on the surface of the core material by the following method.
200 parts of toluene and 30 parts of a styrene-methyl methacrylate copolymer (component ratio 30:70, weight average molecular weight 210,000) were stirred with a stirrer for 60 minutes to obtain a resin coating solution.
100 parts of the resin coating solution and 1.57 parts of carbon black (Regal 330: manufactured by Cabot Corporation) were stirred for 10 minutes at 5,000 rpm using a homogenizer (manufactured by IKA: Ultra Tarrax) to prepare a dispersion.
After 1,000 parts of ferrite core particles and 30.65 parts of the above dispersion were put into a vacuum degassing type kneader coater, the temperature was kept at 60 ° C. and stirred at 40 rpm for 30 minutes, and the temperature was further reduced to 70 ° C. Toluene was distilled off, degassed and dried. Furthermore, carrier (2) was prepared by passing through a mesh having an opening of 75 μm. The volume average particle diameter of the carrier (2) was 38 μm. The SF1 of carrier (2) was 122, and SF2 was 124. The specific gravity of the carrier was 4.5.

(Preparation of carrier (3)) ... PMMA coated carrier The carrier is the same as the carrier (2) production example except that the styrene-methyl methacrylate copolymer is replaced with polymethyl methacrylate (manufactured by Soken Chemical Co., Ltd.). (3) was prepared. The volume average particle diameter of the carrier (3) was 38 μm. The SF1 of carrier (3) was 122, and SF2 was 124. The specific gravity of the carrier was 4.5.

3. Production of electrostatic image developer (production of developer (1))
10 parts by weight of toner (1), 0.15 parts by weight of resin particles (1) (1.5% with respect to the total weight of the colored particles) and 90 parts by weight of carrier (1) were placed in a V blender and stirred for 20 minutes. Thereafter, the mixture was sieved with a 105 μm mesh to prepare Developer (1). When the charge distribution of the developer (1) obtained was measured by a CSG (charge spectrograph) measuring device, the white powder resin particles (1) were charged oppositely to the toner particles.

(Preparation of developer (2))
A developer (2) was produced in the same manner as the developer (1) except that the toner (1) was changed to the toner (2) and the resin particles (1) were changed to the resin particles (2). When the charge distribution of the developer (2) obtained was measured by a CSG (charge spectrograph) measurement device, the white powder resin particles (2) were charged oppositely to the toner particles.

(Preparation of developer (3))
A developer (3) was produced in the same manner as the developer (1) except that the resin particles (1) were changed to resin particles (3). The developer (3) thus obtained was measured for charge distribution using a CSG (charge spectrograph) measuring device. As a result, the white resin particles (3) were charged oppositely to the toner particles.

(Production of developer (4))
A developer (4) was produced in the same manner as the developer (1) except that the resin particles (1) were changed to resin particles (4). The developer (4) thus obtained was measured for charge distribution by a CSG (charge spectrograph) measuring device. As a result, the white resin particles (4) were charged oppositely to the toner particles.

(Preparation of developer (5))
The amount of toner (1) is 10 parts by weight, the amount of resin particles (1) is 0.009 parts by weight (0.09% with respect to the total weight of the colored particles), and the amount of carrier (1) is 90 parts by weight. A developer (5) was produced in the same manner as the developer (1) except that each was changed. The developer (5) thus obtained was measured for charge distribution using a CSG (charge spectrograph) measuring device. As a result, the white resin particles (1) were charged oppositely to the toner particles.

(Production of developer (6))
The amount of toner (1) is 10 parts by weight, the amount of resin particles (1) is 0.55 parts by weight (5.5% with respect to the total weight of the colored particles), and the amount of carrier (1) is 90 parts by weight. A developer (6) was produced in the same manner as the developer (1) except that each was changed. The developer (6) thus obtained was measured for charge distribution using a CSG (charge spectrograph) measuring device. As a result, the white resin particles (1) were charged oppositely to the toner particles.

(Preparation of developer (7))
A developer (7) was produced in the same manner as the developer (1) except that the toner (1) was changed to the toner (3). The developer (7) thus obtained was measured for charge distribution using a CSG (charge spectrograph) measuring device. As a result, the white resin particles (1) were charged oppositely to the toner particles.

(Production of developer (8))
A developer (8) was produced in the same manner as the developer (1) except that the toner (1) was changed to the toner (4). The developer (8) thus obtained was measured for charge distribution using a CSG (charge spectrograph) measuring device. As a result, the white resin particles (1) were charged oppositely to the toner particles.

(Production of developer (9))
Except for changing the toner (1) to the toner (5) and changing the resin particles (1) to Eposter S (360 nm, manufactured by Nippon Shokubai Co., Ltd.), which is a melamine particle, the same as the developer (1). Developer (9) was prepared. When the developer (9) obtained was measured for charge distribution by a CSG (charge spectrograph) measuring device, the melamine particles were slightly oppositely charged from the toner particles.

(Production of developer (10))
A developer (10) was produced in the same manner as the developer (1) except that the resin particles (1) were changed to resin particles (6). The developer (10) thus obtained was measured for charge distribution using a CSG (charge spectrograph) measuring device. As a result, the white resin particles (6) were charged oppositely to the toner particles.

(Production of developer (C1))
The developer (1) is the same as the developer (1) except that the resin particles (1) are not used, the amount of the toner (1) is changed to 10 parts by weight, and the amount of the carrier (1) is changed to 90 parts by weight. C1) was produced.

(Production of developer (C2))
A developer (C2) was produced in the same manner as the developer (1) except that the carrier (1) was changed to the carrier (2).

(Production of developer (C3))
A developer (C3) was produced in the same manner as the developer (1) except that the carrier (1) was changed to the carrier (3). When the charge distribution of the obtained developer (C3) was measured by a CSG (charge spectrograph) measuring device, the white powder resin particles (1) were hardly charged.

III. Evaluation (Examples 1 to 10 and Comparative Examples 1 to 3)
Each of the developers (1) to (10) and (C1) to (C3) produced as described above was evaluated for storage stability, image density stability, and image density uniformity described below. Table 1 shows the evaluation results of each characteristic.

<Preservation evaluation>
The toner was placed in a 10 cm × 10 cm box and left to stand for 24 hours in an environment of 50 ° C./50% RH with a load applied to 20 g / cm ² to obtain a sample. Next, using a powder tester (manufactured by Hosokawa Micron Co., Ltd.), sieves with openings of 53 μm, 45 μm, and 38 μm are arranged in series from the top, and 2 g of the above-mentioned standing sample accurately weighed on the 53 μm sieve is charged. Then, vibration is applied for 90 seconds with an amplitude of 1 mm, and the toner weight on each sieve after vibration is measured, added with a weight of 0.5, 0.3, and 0.1, and calculated as a percentage. did. In this embodiment, the storage stability can be used without any practical problem as long as the weight of the toner after vibration is 40 or less, but is preferably 35 or less, more preferably 30 or less. The evaluation results are shown in Table 1.

<Evaluation of image density stability>
The obtained developer is set in a DocuCentreColor400CP remodeling machine manufactured by Fuji Xerox Co., Ltd., and a solid image of 5 cm x 5 cm is formed at the center of the paper at a development process speed of 200 mm / sec, and 5,000 images are output. did. The image densities of the 10th and 5,000th sheets were measured using an image densitometer (X-Rite 404A: manufactured by X-Rite), and evaluated based on the following evaluation criteria from the image density measurement results. .
A: The image density of the 5,000th sheet is 97% or more with respect to the 10th sheet.
○: The image density of the 5,000th sheet is 94% or more and less than 97% with respect to the 10th sheet.
Δ: The image density of the 5,000th sheet is 90% or more and less than 94% with respect to the 10th sheet.
X: The image density of the 5,000th sheet is less than 90% with respect to the tenth sheet.
The evaluation results are shown in Table 1.

<Evaluation of uniformity of image density>
The obtained developer was set in a DocuCentreColor400CP modified machine manufactured by Fuji Xerox Co., Ltd., and a solid image of 3 cm × 3 cm was formed at the center and four corners of the paper at a development process speed of 200 mm / sec. Output. The density of each of the first to tenth solid images was measured using an image densitometer (X-Rite 404A: manufactured by X-Rite), and the lowest image density value was divided by the highest image density value. The numerical values were evaluated according to the following evaluation criteria as image density fluctuations.
A: Image density variation is 97% or more.
○: Image density variation is 94% or more and less than 97%.
Δ: Image density variation is 90% or more and less than 94%.
X: Image density variation is less than 90%.
The evaluation results are shown in Table 1.

In Example 6, the amount of resin particles added was large, and the fluidity as a developer was lowered, so that the image density uniformity was slightly lowered.
In Example 8, since the size of the inorganic particles is small, the toner storage stability is slightly inferior.
In Comparative Example 3, since the resin particles and the carrier coating agent have the same composition, the resin particles are hardly charged, the effect of electrostatically capturing the inorganic particles is not obtained, and the image density stability is improved. Absent.

1Y, 1M, 1C, 1K, 107 Photoconductor 2Y, 2M, 2C, 2K, 108 Charging roller (charging device, charging means)
3Y, 3M, 3C, 3K Laser beam 3 exposure device (electrostatic latent image forming means)
4Y, 4M, 4C, 4K, 111 developing machine (developing means)
5Y, 5M, 5C, 5K Primary transfer roller (primary transfer means)
6Y, 6M, 6C, 6K, 113 Photoconductor cleaning device (cleaning means)
8Y, 8M, 8C, 8K Toner or developer cartridge 10Y, 10M, 10C, 10K Image forming unit 20 Intermediate transfer belt 22 Drive roller 24 Support roller 26 Secondary transfer roller (secondary transfer means)
28, 115 Fixing device (roll-type fixing means)
30 Intermediate transfer member cleaning device 112 Transfer device 116 Mounting rail 117 Opening portion 118 for static elimination exposure Opening portion 120 for exposure Developer roll (developer holder)
121 Storage means 200 Process cartridge P, 300 Recording paper (transfer object)

Claims (13)

Toner having colored particles containing at least a colorant and a binder resin, and externally adding inorganic particles to the surface of the colored particles;
A carrier having a shape factor SF1 of 100 to 120 and a shape factor SF2 of 100 to 120;
Present in separate state from the toner, have a, a resin particles charged to a polarity opposite from that of the inorganic particles by agitation with the carrier,
At least one of the inorganic particles is a silica particle having a volume average particle diameter of 70 to 520 nm,
The electrostatic charge image developer, wherein the resin particles have a volume average particle diameter of 200 to 4,000 nm .   The electrostatic charge image developer according to claim 1, wherein a volume average particle diameter of the resin particles is larger than a volume average particle diameter of the inorganic particles. The electrostatic image developer according to claim 1, wherein the silica particles are silica particles having a volume average particle diameter of 100 to 500 nm .   The electrostatic image developer according to claim 1, wherein the inorganic particles further include titanium oxide particles.   The electrostatic image developer according to claim 1, wherein the binder resin includes a polyester resin. Characterized in that said resin particles are particles comprising a polymethylmethacrylate, an electrostatic image developer according to any one of claims 1-5. The amount of the resin particles, characterized in that said 0.1-5% by weight relative to the total weight of the colored particles, an electrostatic image developer according to any one of claims 1 to 6 . A developer cartridge, comprising at least a developer, detachable from an image forming apparatus, and the developer being the electrostatic charge image developer according to any one of claims 1 to 7 . Comprising at least a developer holding member is detachable to the image forming apparatus, a process cartridge, characterized in that for holding the electrostatic image developer according to any one of claims 1-7. At least with a photoreceptor,
Charging means for uniformly charging the photoreceptor;
An electrostatic latent image forming means for exposing the charged photoreceptor to form an electrostatic latent image;
Developing means for developing the electrostatic latent image formed on the photoreceptor as a toner image with the electrostatic charge image developer according to any one of claims 1 to 7 ;
Transfer means for transferring a toner image formed on the photoreceptor onto a transfer target;
An image forming apparatus comprising: a fixing unit that fixes the toner image transferred onto the transfer medium. The developing means has a developer holder for supplying the electrostatic image developer to the photoreceptor;
The image forming apparatus according to claim 10 , further comprising an accumulation unit that accumulates the resin particles discharged from the developing unit below the developer holder in a gravitational direction. A charging step for uniformly charging the photoreceptor;
An electrostatic latent image forming step of exposing the charged photoreceptor to form an electrostatic latent image;
A developing step of developing the electrostatic latent image formed on the photoreceptor as a toner image with the electrostatic charge image developer according to any one of claims 1 to 7 ,
A transfer step of transferring a toner image formed on the photoreceptor onto a transfer target;
A fixing step of fixing the toner image transferred onto the transfer medium. The image forming method according to claim 12 , further comprising an accumulation step of accumulating the resin particles discharged in the development step.

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