JP2005202133A - Electrostatic latent image developing two-component developer and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic latent image developing two-component developer which does not cause deterioration of electrostatic properties and toner fluidity due to burying of an external additive in toner particles, can maintain toner fluidity, chargeability, developability and transferability at the same time in any environment over a prolonged period of time, and ensures little wear of a cleaning blade and an electrostatic latent image carrier, and to provide an image forming method by which an image of high image quality can be formed. <P>SOLUTION: The electrostatic latent image developing two-component developer comprises a toner and a carrier, wherein the toner includes toner particles including at least a binder resin and a colorant, and an external additive, and this external additive includes composite resin particles containing inorganic particles. The image forming method uses the developer. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a two-component developer for developing an electrostatic latent image and an image forming method used for developing an electrostatic latent image in electrophotography and electrostatic recording.

  In electrophotography, an electrostatic latent image formed on a latent image carrier (photosensitive member) is developed with toner containing a colorant, and the resulting toner image is transferred onto a transfer member, which is then heated. The latent image carrier is cleaned to form an electrostatic latent image again.

Digitization processing is indispensable as a means for achieving high image quality, and the effect of digitization related to such image quality is that complex image processing can be performed at high speed. This makes it possible to control characters and photographic images separately, and the reproducibility of both qualities is greatly improved compared to analog technology.
In particular, for photographic images, gradation correction and color correction are possible, and this is advantageous compared to analog in terms of gradation characteristics, definition, sharpness, color reproduction, and graininess. However, on the other hand, since it is necessary to faithfully form a latent image produced by an optical system as an image output, as the toner becomes increasingly smaller in particle size, the activity aimed at faithful reproduction is accelerated. However, it is difficult to obtain a stable high image quality simply by reducing the particle size of the toner, and improvement of basic characteristics in development, transfer, and fixing characteristics is more important. In particular, with respect to a color image, improvement of these characteristics is important in order to form a stable high quality image.

  That is, the toner is used for development not only as an aggregate but also as an individual particle during development. For this reason, the toner has sufficient fluidity and fluidity or electrical properties are improved over time. It is necessary not to change depending on the target or environment (temperature, humidity). Another problem is that the amount of charge varies due to the loss of the function of imparting electric charge to the toner from the fluidity imparting agent itself due to the release of the fluidity imparting agent from the toner surface.

  In the two-component developer, it is necessary to prevent the phenomenon that the toner is fixed to the carrier surface, that is, so-called toner filming. Due to the advancement of finer toner and carrier technology for high image quality, the amount of charge changes in response to slight changes in temperature and humidity, and uneven mixing due to the release of fluidity-imparting agents from the toner surface. As a result, the mixing property is lowered and a toner lump is easily generated.

  Further, in cleaning, a cleaning property is required such that residual toner is easily detached from the surface of the photoreceptor. In order to satisfy these requirements, in a dry developer, a one-component developer or two-component developer in which inorganic fine powders such as silica, organic fine powders such as fatty acids, metal salts and derivatives thereof, and fluorine resin fine powders are externally added. Various agents have been proposed to improve fluidity, durability or cleaning properties.

  However, inorganic compounds such as silica, titania, and alumina, which have been proposed as additives in the past, greatly improve fluidity, but have a great influence on charging. For example, generally used silica-based fine powder has a strong negative polarity, and excessively increases the chargeability of a negatively chargeable toner, particularly at low temperatures and low humidity, while moisture at high temperatures and high humidity. Since the chargeability is reduced by taking in, there is a problem that a large difference is caused in the chargeability between the two. As a result, density reproduction failure and background fogging may occur.

  In order to improve these points, various proposals have been made to use a surface-treated inorganic fine powder. For example, Patent Literature 1 to Patent Literature 3 describe hydrophobizing the surface of silica fine particles. However, sufficient effects cannot always be obtained simply by using these inorganic fine powders.

  Further, as a method for alleviating the negative chargeability of toner particles, a method of externally adding silica fine particles surface-treated with amino-modified silicone oil or the like is known (see Patent Documents 4 and 5). However, these surface treatments can suppress an excessive increase in charge of the negatively chargeable toner, but cannot sufficiently improve the environmental dependency of the silica fine powder itself.

  Furthermore, as a method for improving the triboelectric chargeability, storage stability and fluidity of the toner, silica fine particles coated with a polymer having a triboelectric chargeability different from the outer particle polymer of the toner particles are externally added to the toner particles. The method to do is known (refer patent document 6). However, this method is intended to impart triboelectric chargeability and cannot sufficiently improve the environment dependency.

  In addition, when the external additive is lost due to some impact and remains on the photoconductor, there are minute scratches on the photoconductor or nuclei such as residual toner that cannot be completely transferred. External additives are likely to be trapped, and there is a risk of causing problems such as toner slipping from the cleaning blade and occurrence of toner filming.

  As means for suppressing detachment of inorganic fine particles externally added to the toner surface, means for fixing inorganic fine particles to the toner surface by mechanochemical reaction (mechanical impact) is disclosed (see Patent Documents 7 and 8). . In this case, although the inorganic fine particles are fixed, the expected fluidity cannot be obtained, and the mixing property of the developer is lowered, so that it is difficult to obtain a stable charging characteristic.

  In order to improve fluidity, chargeability, and transferability, it has been proposed to make the toner shape closer to a spherical shape (see Patent Document 9). However, by making the toner spherical, the following problems are likely to occur. That is, at present, an organic photoreceptor containing an organic photoconductive substance is most widely used as a latent image carrier used in an electrophotographic image forming apparatus, but a spherical residual toner is an organic photoreceptor. There is a problem that the adhesion force to the surface is high, the wear of the cleaning blade and the photoconductor is promoted, and the life of the cleaning blade and the photoconductor is shortened. In addition, cleaning problems are likely to occur, and there are problems such as image smearing and charging member contamination.

  A technique of adding a fatty acid metal salt as a cleaning aid for preventing the occurrence of poor cleaning is known (Patent Document 10, etc.). However, when the fatty acid metal salt having high water absorption coats the surface of the toner (filming), the chargeability or charge retention ability of the toner decreases. In particular, when printing is performed at a high temperature and high humidity, there is a problem that fog is generated, or when the image forming apparatus is stopped for a long time and then the gradation is changed, and the image image looks dark.

  A technique for adding an abrasive external additive to toner is also known as a measure for preventing the occurrence of defective cleaning. Abrasive external additives have the effect of polishing the photoreceptor surface and preventing photoreceptor filming due to discharge products such as toner, nitrogen oxides, and ammonium nitrate, but especially when using organic photoreceptors. However, there is a problem that the life of the photoreceptor is shortened.

  In order to solve this problem, there has been proposed a toner which gives abrasiveness to the cleaner part by adding inorganic particles having a number average particle size of about 80 to 800 nm, particularly strontium titanate particles, to the toner particles. However, even if the strontium titanate particles having a number average particle size of about 80 to 800 nm are subjected to a hydrophobizing treatment, the surface treatment agent is not treated well with the strontium titanate particles, and the hydrophobicity is not improved so much. However, even if such hydrophobic strontium titanate particles are added, there has been a problem that the charge level controllability and charging environment stability of the toner cannot be significantly improved.

  So far, Patent Documents 11 and 12, etc. have proposed toners containing inorganic / organic composite fine particles in which inorganic fine particles having a number average primary particle size of 5 to 100 nm are fixed to the surface of the organic fine particles at a fixing degree of 20 to 75%. ing. However, as the organic fine particles, resin particles made of acrylic polymer, styrene polymer, styrene-acrylic polymer, etc. are used, and in these resin particles, the organic fine particles themselves are deformed by stress in the machine. Therefore, it is difficult to maintain the initial characteristics stably for a long time.

  On the other hand, particularly with respect to toner, it is reported that the toner is agitated in a developing device and the fine structure change of the toner surface easily occurs and the transferability is greatly changed (see Patent Document 13). Further, as described above, in order to improve fluidity, chargeability, and transferability, it has been proposed to make the toner shape closer to a spherical shape (see Patent Document 9). However, by making the toner spherical, the following problems are likely to occur. The developing device is provided with a transport amount control plate for controlling the developer transport amount to be constant, and can be controlled by swinging the gap between the mag roll and the transport amount control plate. However, when a spherical toner is used, the fluidity as a developer is improved, and at the same time, it is hardened and the bulk density is increased. As a result, there is a phenomenon in which developer accumulation occurs in the conveyance regulation region, and the conveyance amount becomes unstable. By controlling the surface roughness on the mag roll and reducing the gap between the control plate and the mag roll, it is possible to improve the transport amount, but the packing property due to the developer pool becomes more and more, and the stress applied to the toner also increases accordingly. Become. As a result, it has been confirmed that the change in the fine structure of the toner surface, in particular, the embedding or peeling of the external additive easily occurs, resulting in a problem that the development and transferability are greatly changed from the initial stage.

  In order to improve these, it has been reported that spherical toner and non-spherical toner can be combined to suppress the packing property and achieve high image quality (see Patent Document 14). However, these are effective in suppressing packing properties, but non-spherical toner tends to remain as a transfer residue, and high transfer efficiency cannot be achieved.

  Also, in order to improve the developability, transferability, and cleaning properties of the spherical toner, two types of inorganic fine particles having different particle sizes, particles having an average particle size of 5 mμ to 20 mμ and particles having an average particle size of 20 mμ to 40 mμ, respectively. And adding a specific amount is disclosed (see Patent Document 15). These can initially provide high developability, transferability, and cleaning properties, but in any case, the force applied to the toner over time cannot be reduced, so that the external additives can be easily buried or peeled off. Occurs, and development and transferability are greatly changed from the initial stage.

  On the other hand, it is disclosed that it is effective to use inorganic fine particles having a large particle diameter in order to suppress the burying of the external additive in the toner against such stress. (See Patent Documents 13, 16, and -17). However, in any case, since the inorganic fine particles have a large specific gravity, if the external additive particles are enlarged, peeling of the external additive cannot be avoided due to the stirring stress in the developing device. In addition, since the inorganic fine particles do not have a perfect spherical shape, it is difficult to control the spike of the external additive to be constant when it is deposited on the toner surface. This causes variations in the micro-surface convex shape that functions as a spacer, and stress is selectively applied to the convex portion, so that the burying or peeling of the external additive is further accelerated, which is not sufficient.

  It is also disclosed that it is effective to use large-diameter silica having a low true specific gravity (see Patent Document 18). This silica is spherical, monodispersed and has a low true specific gravity, and is a method that takes the above problems into consideration.Since silica has a high Mohs hardness, it may damage the photoreceptor or members when considering long-term stability. This is not sufficient for the recent demand for further long-term stability.

Also, a technique for adding 50 to 200 nm organic fine particles to the toner in order to effectively develop the spacer function is disclosed. (See Patent Document 19). By using spherical organic fine particles, it is possible to effectively exhibit a spacer function in the initial stage. However, although the organic fine particles are less likely to be buried or peeled off with respect to stress over time, it is difficult to stably express a high spacer function because the organic fine particles themselves are deformed.
Further, it is conceivable to obtain a spacer effect by adding a large amount of organic fine particles to the toner surface or using organic fine particles having a large particle diameter, but in this case, the characteristics of the organic fine particles are greatly reflected. In other words, the influence on the powder properties such as fluidity inhibition and thermal aggregation deterioration of the inorganic fine particle-added toner, and the organic fine particles themselves have a charge imparting ability, and the degree of control freedom from the viewpoint of charging is reduced. This will affect the charging and development.

  Recently, there is a high demand for colorization, especially on-demand printing, and there is a technique for forming a multicolor image on a transfer belt to cope with high-speed copying, transferring the multicolor image to an image fixing material at a time, and fixing it. It has been reported (see Patent Document 20). If the process of transferring from the photoconductor to the transfer belt is the primary transfer, and the process of transferring from the transfer belt to the transfer body is the secondary transfer, the transfer is repeated twice, and a technique for improving the transfer efficiency becomes more and more important. In particular, in the case of secondary transfer, a multicolor image is transferred at once, and since the transfer body (for example, in the case of paper, its thickness, surface property, etc.) changes variously, charging, developing, It is necessary to control transferability extremely high.

On the other hand, a method has been proposed in which the volume resistivity of a carrier is controlled to faithfully reproduce high image quality, particularly halftone, solid black, and characters (see Patent Documents 21 to 23). In any of these methods, the resistance is adjusted according to the type and amount of the carrier coating layer, and initially the target volume specific resistance is obtained and high image quality is exhibited, but the carrier coating is applied under stress in the developing device. Layer peeling or the like occurs, and the volume resistivity changes greatly. Therefore, it is difficult to achieve high image quality over a long period of time.
In addition, a method for adjusting volume resistivity by adding carbon black to the carrier coating layer has been proposed (see Patent Document 24). Although the change in volume resistivity due to the peeling of the coating layer can be suppressed by this method, the external additive or toner component added to the toner adheres to the carrier and changes the volume resistivity of the carrier. It was difficult to develop high image quality for a long time like other carriers.
JP-A-46-5782 JP-A-48-47345 JP-A-48-47346 JP-A-64-73354 JP-A-1-237561 JP-A 64-6964 JP-A-2-61649 Japanese Patent Laid-Open No. 2-77756 Japanese Patent Laid-Open No. 62-184469 JP-A-11-323396 Japanese Patent Laid-Open No. 2002-287408 Japanese Patent Laid-Open No. 2002-214823 Japanese Patent Laid-Open No. 10-312089 JP-A-6-308759 Japanese Patent Laid-Open No. 3-100161 JP-A-7-28276 (JP-A-9-319134) JP 2001-66820 A JP-A-6-266152 See JP-A-8-11507. JP 56-125751 A, JP-A-62-267766, Japanese Patent Publication No. 7-120086 JP-A-4-40471

An object of the present invention is to solve the above conventional problems and achieve the following object.
That is, the present invention does not cause a decrease in charging characteristics and toner fluidity due to the embedment of the external additive in the toner particles, and the toner fluidity, charging performance, developability, and transferability are simultaneously and depending on the environment. It is an object of the present invention to provide a two-component developer for developing an electrostatic latent image that can be maintained over a long period of time and has little wear on a cleaning blade or an electrostatic latent image carrier.
Furthermore, an object of the present invention is to provide an image forming method capable of forming a high quality image.

  As a result of intensive studies to achieve the above object, the present inventors have achieved that the above object can be achieved by externally adding composite resin particles containing inorganic particles to the toner particles. When the toner and the composite resin particles containing inorganic particles having a specific particle diameter are used in combination, it has been found that transferability is particularly excellent, and the present invention has been completed.

Means for solving the above problems are as follows.
<1> A two-component developer for developing an electrostatic latent image containing a toner and a carrier, wherein the toner contains toner particles containing at least a binder resin and a colorant and an external additive, The two-component developer for developing an electrostatic latent image, wherein the external additive contains composite resin particles containing inorganic particles.

  <2> The two-component developer for developing an electrostatic latent image according to <1>, wherein the toner particles contain a release agent.

  <3> The two-component developer for developing an electrostatic latent image according to claim 1 or 2, wherein the composite resin particles have a volume average particle diameter of 0.05 to 2 μm.

<4> When the number average particle diameter of the composite resin particles is d ₅₀ , in the particle size distribution of the composite resin particles, the ratio of particles of 1/2 × d ₅₀ or less and the ratio of particles of 2 × d ₅₀ or more Are the two-component developer for developing an electrostatic latent image according to any one of <1> to <3>, wherein each is 20% by number or less.

  <5> The electrostatic latent image according to any one of <1> to <4>, wherein the inorganic particles contained in the composite resin particles are partially exposed on the surface of the composite resin particles. It is a two-component developer for development.

  <6> The two-component developer for electrostatic latent image development according to any one of <1> to <5>, wherein the composite resin particle includes a resin containing a nitrogen atom. .

  <7> The two-component developer for developing electrostatic latent images according to any one of <1> to <6>, wherein the resin containing a nitrogen atom is a melamine resin.

  <8> The two-component developer for developing an electrostatic latent image according to any one of claims 1 to 7, wherein an average shape factor SF1 of the toner is in a range of 100 to 140.

  <9> The average shape factor SF1 of the toner is in the range of 125 to 140, the average shape factor SF2 is in the range of 105 to 130, and the volume average particle size of the composite resin particles is in the range of 80 to 300 nm. The two-component developer for developing an electrostatic latent image according to any one of the above items <1> to <8>.

  <10> The electrostatic according to any one of <1> to <9>, wherein the carrier has a resin coating layer in which a conductive material is dispersed and contained in a matrix resin on a core material surface. A two-component developer for developing a latent image.

<11> A charging means for uniformly charging an electrostatic latent image carrier (hereinafter sometimes referred to as “photosensitive member” as appropriate), and exposing the surface of the charged electrostatic latent image carrier to an electrostatic latent image. A latent image forming means, a developing means for developing the electrostatic latent image into a toner image using a developer containing toner, a transfer means for transferring the formed toner image to a recording material, and a transferred toner image An image forming method for forming an image using an image forming apparatus including a fixing unit that fixes the image on the surface of the recording material,
The developer according to any one of <1> to <10>, wherein the transfer unit develops each color toner on a latent image carrier and transfers it to an intermediate transfer member. In addition, the image forming method is characterized in that it is a transfer means for transferring each color toner to a recording material at a time. .

The action of the developer for developing an electrostatic latent image of the present invention (hereinafter referred to as “the developer of the present invention” as appropriate) is not clear, but is presumed as follows.
When conventional surface-treated or untreated inorganic particles or organic particles such as silica and titania are used as external additives, the environmental stability is not sufficiently improved. However, in the present invention, although details are unclear, the composite resin particles containing inorganic particles (hereinafter sometimes simply referred to as “composite resin particles”) are used as external additives. It is considered that the environmental stability such as chargeability is improved by the action of the inorganic particles contained in the resin particles. For example, melamine particles are strong positively-charged particles and have large environmental fluctuations in their characteristics. However, when silica is incorporated into the particles as inorganic particles, silica is a strong negatively-charged particle and has large environmental fluctuations in its characteristics. Fortunately, it seems that the particles as a whole exhibit positive charging characteristics that are stable against environmental fluctuations.

  The composite resin particles in the present invention are roughly spherical, but some of the inorganic particles are exposed to the surface while being incorporated into the resin particles while maintaining the shape, so that the composite particles The surface of the resin particles is uneven when viewed microscopically. Therefore, the number of contact points between the particles is smaller than when resin particles or inorganic particles are used alone, which is effective in preventing toner aggregation and burying of external additives. In particular, the spacer effect can be exhibited.

  In addition, the developer of the present invention is effective in preventing an image flow due to adhesion of paper dust or the like to the surface of the photoreceptor without causing a secondary failure due to toner aggregation or the like. That is, the composite resin particles hold inorganic particles (very harder than the cured resin) on the particle surface, so that the polishing effect can be exerted, and the particle size distribution is small and very sharp. This is because scratches are not generated, but there are few small-diameter particles that are difficult to clean, so that they themselves do not adhere to the photoreceptor and become contaminated.

  Furthermore, when the toner is negatively charged, the composite resin particles containing inorganic particles are positively charged, so that the electrostatic adhesion to the toner particles reduces the separation from the toner particle surface, and the external additive itself Is not attached to the photoreceptor. Further, it is considered that the toner particles are dispersed in the form of primary particles on the toner surface and do not cause charging failure of the toner due to aggregation. Further, since talc is usually negatively charged, it is considered that talc removal is effectively performed because it attracts electrostatically with the composite resin particles in the present invention.

  According to the present invention, the toner fluidity, chargeability, developability, and transferability can be maintained over a long period of time without causing the external additive to be buried in the toner, and the cleaning blade and the photoconductor. It is possible to provide a two-component developer for developing an electrostatic latent image and an image forming method capable of forming a high-quality image.

[Two-component development for electrostatic latent image development]
Hereinafter, the developer of the present invention will be described in detail.
The developer of the present invention is a two-component developer for developing an electrostatic latent image containing a toner and a carrier, and the toner contains toner particles containing at least a binder resin and a colorant and an external additive. Thus, the external additive contains composite resin particles containing inorganic particles.
In the present invention, by using spherical composite cured resin particles containing inorganic particles as an external additive for toner particles, development that exhibits stable charging characteristics regardless of the environment (high temperature and high humidity, low temperature and low humidity) or over time. An agent can be obtained.
The toner contained in the developer of the present invention may be either a magnetic toner containing a magnetic material or a non-magnetic toner not containing a magnetic material.

  In the present invention, when composite resin particles having a specific volume average particle size SF1 and SF2 in a specific range and a specific volume average particle size are used in the first aspect, transferability may be increased. An excellent effect can be exhibited.

(Composite resin particles)
Hereinafter, first, the composite resin particles in the present invention will be described in detail.
In the present invention, the composite resin particle is a resin particle that contains inorganic particles in the resin particles while maintaining the shape thereof and contains a part of the inorganic particles exposed on the surface of the resin particles. The surface of is said to be in an uneven shape when viewed microscopically.
The composite resin particles containing inorganic particles in the present invention preferably have a volume average particle size in the range of 0.05 to 2.0 μm, more preferably in the range of 0.10 to 0.50 μm. . When the volume average particle size is less than 0.05 μm, the effect of removing paper dust or the like is small, while when the volume average particle size is greater than 2.0 μm, the photoconductor is worn and the life of the photoconductor is shortened.
The volume average particle diameter of the composite resin particles is, for example, a particle when the cumulative volume distribution reaches 50% as measured by a laser diffraction / scattering particle size distribution analyzer [Mastersizer 2000 (trade name), manufactured by Malvern Co., Ltd.]. It means the diameter.

  In the present invention, composite resin particles having a volume average particle diameter of 80 to 300 nm are used together with a toner having an average shape factor (SF1 and SF2) in a specific range, thereby further improving transferability. Can be improved. The toner will be described in detail later.

  In the composite resin particles of the present invention, preferably, the true specific gravity is controlled to be 2.0 or less, whereby peeling from the toner particles can be suppressed. In addition, since the composite resin particles of the present invention have a form in which the inorganic particles are buried on the surface, compared with the case where only the resin particles are used alone, there are few contact points and it is difficult to form strong aggregation. Further, by controlling the true specific gravity to be 1.3 or more, aggregation and dispersion can be further suppressed. The suitable range of the true specific gravity of the composite resin particles in the present invention is in the range of 1.4 to 1.8.

  General fumed silica has a true specific gravity of 2.2, and the maximum particle size of 50 nm is a limit from the viewpoint of production. Moreover, although the particle size can be increased as an aggregate, uniform dispersion and a stable spacer effect cannot be obtained. On the other hand, other typical inorganic fine particles used as an external additive include titanium oxide (true specific gravity 4.2, refractive index 2.6), alumina (true specific gravity 4.0, refractive index 1.8), oxidation Zinc (true specific gravity: 5.6, refractive index: 2.0) can be mentioned, but all of them have a high true specific gravity, and if the particle size is larger than 80 nm, which effectively expresses the spacer effect, the toner particles are easily peeled off. The particles easily move to a charge imparting member or a latent image carrier, causing a decrease in charge or an image quality defect. Further, since the refractive index is high, it is not suitable for producing a color image to use an inorganic substance having a large particle diameter.

  When the volume average particle size of the composite resin particles is in the range of 80 to 300 nm, the composite resin particles are more effectively prevented from being embedded in the toner particles and detached from the toner particles. In particular, the spacer effect can be maintained. Therefore, an excellent effect can be exhibited particularly in transferability.

  Since the composite resin particles in the present invention are well-dispersed and spherical, they can be uniformly dispersed on the surface of the toner particles and a stable spacer effect can be obtained.

In the present invention, it is desirable that the particle size distribution of the composite resin particles is controlled within a certain range. Specifically, when the number average particle diameter is d ₅₀ , the ratio of particles having a particle size of ½ × d ₅₀ or less is 20% by number or less, and the proportion of particles having a particle size of 2 × d ₅₀ or more. Is preferably 20% by number or less.
The ratio is more preferably 15% by number or less, and further preferably 10% by number or less.

When the ratio of fine particles having a particle size of 1/2 × d ₅₀ or less exceeds 20% by number, the fine particles having a small diameter come to adhere to the photoreceptor. Further, the chargeability of the toner is unstable. On the other hand, if the proportion of fine particles having a particle size of 2 × d ₅₀ or more exceeds 20% by number, the photoconductor may be worn to shorten the photoconductor life.

  The number average particle diameter can be measured by, for example, a laser diffraction / scattering particle size distribution measuring apparatus [Mastersizer 2000 (trade name), manufactured by Malvern, Inc.].

  In the present invention, the “number average particle diameter” means a particle diameter when the accumulation by the number distribution reaches 50%, and is generally referred to as a number median diameter.

  The amount of the composite resin particles added to the toner particles described later is preferably in the range of 0.1 to 3.0% by mass, more preferably 0.2 to 1.0% by mass, with respect to 100 parts by mass of the toner particles. It is. If the amount added is less than 0.1% by mass, the density of the formed image and the image flow after continuous printing under high temperature and high humidity may deteriorate when stored and used under high temperature and high humidity. On the other hand, if the amount added is more than 3.0% by mass, the photoconductor may be worn out and the life of the photoconductor may be shortened.

  The resin contained in the composite resin particles in the present invention may be appropriately selected from various resins such as a thermoplastic resin and a thermosetting resin depending on the desired function, but in the case of a thermoplastic resin. Since the hardness may not be sufficiently increased, it is preferable to use a thermosetting resin.

  Specific examples of the thermoplastic resin include polyolefin resins such as polyethylene, polypropylene; polyvinyl and polyvinylidene resins such as polystyrene, acrylic resin, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride. , Polyvinyl carbazole, polyvinyl ether and polyvinyl ketone; vinyl chloride-vinyl acetate copolymer; styrene-acrylic acid copolymer; straight silicone resin composed of organosiloxane bond or a modified product thereof; fluororesin such as polytetrafluoroethylene, polyfluoride And vinyl chloride, polyvinylidene fluoride, polychlorotrifluoroethylene; polyester; polycarbonate and the like. It is also possible to obtain cured resin particles by simultaneously using a crosslinking component such as divinylbenzene together with the resin formation.

  Examples of the thermosetting resin include phenol resin; amino resin such as urea-formaldehyde resin, melamine resin, benzoguanamine resin, urea resin, polyamide resin; epoxy resin, and the like.

  Among these resins, it is preferable to use a resin containing a nitrogen atom having an electron-donating ability. In particular, it is preferable to use a melamine resin that is thermosetting and has a high electron-donating ability.

  In addition, in order to give composite resin particles containing inorganic particles a polishing effect on the surface of the photoreceptor, it is necessary to have a high hardness and to maintain a spherical shape even under the stress of a cleaning blade that contacts the photoreceptor. It is preferable to use thermosetting resin particles that are easy to raise.

  Examples of the inorganic particles include inorganic particles such as Mohs hardness of 3 to 9 and particle size (primary particle size) in the range of 5 to 500 nm, and shapes such as amorphous, spherical, and cubic.

  Examples of the inorganic particles include carbon black, silica, alumina, titania, zinc oxide, strontium titanate, cerium oxide, and calcium carbonate. For the purpose of adjusting the charge imparting ability, silica is used. preferable.

  As a method of producing composite resin particles containing inorganic particles in the present invention, a method of producing a granular resin using a polymerization method such as suspension polymerization, emulsion polymerization, suspension polymerization, etc., dispersing a monomer or oligomer in a poor solvent Then, a method of granulating by surface tension while performing a crosslinking reaction, a method of mixing and reacting a low molecular component and a crosslinking agent by melt kneading, etc., and then pulverizing to a predetermined particle size by wind force or mechanical force, etc. Can be mentioned.

  The method for producing composite resin particles used in the present invention is not particularly limited. For example, spherical composite melamine resin particles (composite resin particles) containing silica as inorganic particles by the following steps (a) and (b). Can be manufactured.

(A) In an aqueous medium, a melamine compound and an aldehyde compound are reacted under basic conditions under a suspension of colloidal silica having an average particle size of 5 to 70 nm, and the initial stage of a melamine resin soluble in water A step of generating an aqueous solution of the condensate, and a step of adding spherical acid melamine resin particles by adding an acid catalyst to the aqueous solution obtained in steps (b) and (a).

  As the melamine compound used in the step (a), known compounds such as melamine and substituted melamine compounds in which the hydrogen of the amino group of melamine is substituted with an alkyl group, an alkenyl group, or a phenyl group can be used. Of these, inexpensive melamine is most preferred.

Examples of the aldehyde compound used in the step (a) include formaldehyde, paraformaldehyde, acetaldehyde, benzaldehyde, and furfural, but formaldehyde and paraformaldehyde that are inexpensive and have good reactivity with the melamine compound are preferable.
As an aldehyde compound, it is preferable to mix | blend 1.1-6.0 mol per effective aldehyde group with respect to 1 mol of said melamine compounds, especially 1.2-4.0 mol.

  As colloidal silica used at the said (a) process, what has the average particle diameter of the range of 5-70 nm is used. Although powdered colloidal silica such as precipitated silica powder and vapor phase method silica powder can be used, it is preferable to use a colloidal silica sol stably dispersed to the primary particle level in a medium.

  When the average particle diameter of colloidal silica exceeds 70 nm, the composite cured melamine resin precipitated in the step (b) may be difficult to become spherical particles. If it is less than 5 nm, the particle size distribution may be difficult to control sharply. In general, the average particle size of the spherical composite melamine resin particles becomes smaller as the melamine resin concentration is lower and the average particle size of the colloidal silica is smaller.

  The amount of colloidal silica added is preferably in the range of 0.5 to 100 parts by mass, particularly 1 to 50 parts by mass with respect to 100 parts by mass of the melamine compound. If the addition amount is less than 0.5 parts by mass, it is difficult to obtain spherical composite melamine resin particles in step (b). In addition, spherical composite melamine resin particles can be obtained even when the addition amount exceeds 100 parts by mass, but in this case, it is not preferable because fine and non-spherical aggregated particles are by-produced as compared with the intended spherical composite melamine resin particles.

  If necessary, the spherical composite melamine resin particles may be surface-coated with inorganic compound particles. As a surface coating method, for example, spherical composite melamine resin particles and inorganic compound particles may be mixed directly or in an aqueous medium. It is also possible to coat the surface with inorganic compound particles by a general vapor deposition method such as a vacuum vapor deposition method, a sputtering method, or an ion plating method.

Furthermore, you may surface-treat the colloidal silica which exists in the spherical composite melamine resin particle surface as needed. For example, the surface treatment can be performed with a silicon compound represented by the following formulas (I) to (III).
R ₁ Si (X) ₃ (I)
R ₁ R ₂ Si (X) ₂ ... (II)
R ₁ R ₂ R ₃ SiX (III)

In the above formulas, R ₁ represents an alkyl group having 1 to 20 carbon atoms or a perfluoroalkyl group, and R ₂ and R ₃ are each a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or a perfluoroalkyl group. Or an aryl group, and X represents a chlorine atom, an alkoxy group, an NCO group, or an acetoxy group.

  By such surface treatment, it is possible to prevent the occurrence of comet and filming on the surface of the photosensitive member, and to improve the dispersibility and adhesion to the toner, as well as the charging stability and charge exchange property associated with the hydrophobicity control. Expect more.

Here, the following can be illustrated as a processing agent (coupling agent) used for the said surface treatment.
Examples of the compound represented by the formula (I) include CH ₃ Si (Cl) ₃ , CH ₃ Si (OCH ₃ ) ₃ , CH ₃ Si (OC ₂ H ₅ ) ₃ , and CH ₃ CH ₂ Si (OCH ₃ ) _3. CH ₃ (CH ₂ ) ₂ Si (OCH ₃ ) ₃ , CH ₃ (CH ₂ ) ₃ Si (OCH ₃ ) ₃ , CH ₃ (CH ₂ ) ₄ Si (OCH ₃ ) ₃ , CH ₃ (CH ₂ ) ₅ Si (OCH ₃ ) ₃ , CH ₃ (CH ₂ ) ₆ Si (OCH ₃ ) ₃ , CH ₃ (CH ₂ ) ₇ Si (OCH ₃ ) ₃ , CH ₃ (CH ₂ ) ₈ Si (OCH ₃ ) ₃ , CH ₃ (CH ₂ ) ₉ Si (OCH ₃ ) ₃ , CH ₃ (CH ₂ ) ₁₀ Si (OCH ₃ ) ₃ , CH ₃ (CH ₂ ) ₁₁ Si (OCH ₃ ) ₃ , CH ₃ (CH ₂ ) ₁₂ Si ( _{OCH 3) 3, CH 3 (} CH 2) 13 Si (OCH 3) 3, CH 3 (CH 2) 14 Si (OCH 3) 3, CH 3 (CH 2) 15 Si _{OCH 3) 3, CH 3 (} CH 2) 16 Si (OCH 3) 3, CH 3 (CH 2) 17 Si (OCH 3) 3, CH 3 (CH 2) 18 Si (OCH 3) 3, CH 3 ( CH ₂ ) ₁₉ Si (OCH ₃ ) ₃ , CH ₃ (CH ₂ ) ₅ Si (OCO ₂ H ₅ ) ₃ , CH ₃ (CH ₂ ) ₆ Si (OCO ₂ H ₅ ) ₃ , CH ₃ (CH ₂ ) ₇ Si (OCO ₂ H ₅ ) ₃ , CH ₃ (CH ₂ ) ₈ Si (OCO ₂ H ₅ ) ₃ , CH ₃ (CH ₂ ) ₉ Si (OCO ₂ H ₅ ) ₃ , CH ₃ (CH ₂ ) ₁₀ Si ( OCO ₂ H ₅ ) ₃ , CH ₃ (CH ₂ ) ₁₁ Si (OCO ₂ H ₅ ) ₃ , CH ₃ (CH ₂ ) ₁₂ Si (OCO ₂ H ₅ ) ₃ , CH ₃ (CH ₂ ) ₁₃ Si (OCO ₂ H ₅ ) ₃ , CH ₃ (CH ₂ ) ₁₄ Si (OCO ₂ H ₅ ) ₃ , CH ₃ (CH ₂ ) ₁₅ Si (OCO ₂ H ₅ ) ₃ , CH ₃ (CH ₂ ) ₁₆ Si (OCO) _{2 H 5) 3, CH 3} (CH 2) 17 Si (OCO 2 H 5) 3, CH 3 (CH 2) 18 Si (OCO 2 H 5) 3, CH 3 (CH 2) 19 Si (OCO 2 H ₅ ) ₃ , CF ₃ Si (OCH ₃ ) ₃ , CH ₃ Si (NCO) _{3 and the} like.

Examples of the compound represented by the formula (II) include (CH ₃ ) ₂ SiC ₁₂ , (CH ₃ ) ₂ Si (OCH ₃ ) ₂ , (CH ₃ ) ₂ Si (OC ₂ H ₅ ) ₂ , (CH ₃ ). (CH ₃ CH ₂ ) Si (OCH ₃ ) ₂ , (CH ₃ ) [CH ₃ (CH ₂ ) ₂ ] Si (OCH ₃ ) ₂ , (CH ₃ ) [CH ₃ (CH ₂ ) ₃ ] Si (OCH ₃ ) ₂ , (CH ₃ ) [CH ₃ (CH ₂ ) ₄ ] Si (OCH ₃ ) ₂ , (CH ₃ ) [CH ₃ (CH ₂ ) ₅ ] Si (OCH ₃ ) ₂ , (CH ₃ ) [CH ₃ (CH ₂ ) ₆ ] Si (OCH ₃ ) ₂ , (CH ₃ ) [CH ₃ (CH ₂ ) ₇ ] Si (OCH ₃ ) ₂ , (CH ₃ ) [CH ₃ (CH ₂ ) ₈ ] Si (OCH ₃ ) ₂ , (CH ₃ ) [CH ₃ (CH ₂ ) ₉ ] Si (OCH ₃ ) ₂ , (CH ₃ ) [CH ₃ (CH ₂ ) ₁₀ ] Si (OCH ₃ ) ₂ , (CH ₃ ) [CH ₃ (CH _{2 11} ] Si (OCH ₃ ) ₂ , (CH ₃ ) [CH ₃ (CH ₂ ) ₁₂ ] Si (OCH ₃ ) ₂ , (CH ₃ ) [CH ₃ (CH ₂ ) ₁₃ ] Si (OCH ₃ ) ₂ , (CH ₃ ) [CH ₃ (CH ₂ ) ₁₄ ] Si (OCH ₃ ) ₂ , (CH ₃ ) [CH ₃ (CH ₂ ) ₁₅ ] Si (OCH ₃ ) ₂ , (CH ₃ ) [CH ₃ (CH ₂ ) ₁₆ ] Si (OCH ₃ ) ₂ , (CH ₃ ) [CH ₃ (CH ₂ ) ₁₇ ] Si (OCH ₃ ) ₂ , (CH ₃ ) [CH ₃ (CH ₂ ) ₁₈ ] Si (OCH ₃ ) ₂ , (CH ₃ ) [CH ₃ (CH ₂ ) ₁₉ ] Si (OCH ₃ ) ₂ , (CH) ₂ Si (NCO) _{2 and the} like.

Examples of the compound represented by the formula (III) include (CH ₃ ) ₃ SiCl, (CH ₃ ) ₃ Si (OCH ₃ ), (CH ₃ ) ₃ Si (OC ₂ H ₅ ), (CH ₃ ) ₂ (CH _{3 CH 2) Si (OCH 3} ), (CH 3) 2 [CH 3 (CH 2) 2] Si (OCH 3), (CH 3) 2 [CH 3 (CH 2) 3] Si (OCH 3), (CH ₃ ) ₂ [CH ₃ (CH ₂ ) ₄ ] Si (OCH ₃ ), (CH ₃ ) ₂ [CH ₃ (CH ₂ ) ₅ ] Si (OCH ₃ ), (CH ₃ ) ₂ [CH ₃ (CH ₂ ) ₆ ] Si (OCH ₃ ), (CH ₃ ) ₂ [CH ₃ (CH ₂ ) ₇ ] Si (OCH ₃ ), (CH ₃ ) ₂ [CH ₃ (CH ₂ ) ₈ ] Si (OCH ₃ ), (CH ₃ ) ₂ [CH ₃ (CH ₂ ) ₉ ] Si (OCH ₃ ), (CH ₃ ) ₂ [CH ₃ (CH ₂ ) ₁₀ ] Si (OCH ₃ ), (CH ₃ ) ₂ [CH ₃ (CH ₂ ) ₁₁ ] Si (OCH ₃ ), (CH ₃ ) ₂ [CH ₃ (CH ₂ ) ₁₂ ] Si (OCH ₃ ), (CH ₃ ) ₂ [CH ₃ (CH ₂ ) ₁₃ ] Si (OCH ₃ ), (CH ₃ ) ₂ [CH ₃ (CH ₂ ) ₁₄ ] Si (OCH ₃ ), (CH ₃ ) ₂ [CH ₃ (CH ₂ ) ₁₅ ] Si (OCH ₃ ), (CH ₃ ) ₂ [CH ₃ (CH ₂ ) ₁₆ ] Si (OCH ₃ ), (CH ₃ ) ₂ [CH ₃ (CH ₂ ) ₁₇ ] Si (OCH ₃ ), (CH ₃ ) ₂ [CH ₃ (CH ₂ ) ₁₈ ] Si (OCH ₃ ), (CH ₃ ) ₂ [CH ₃ (CH ₂ ) ₁₉ ] Si (OCH ₃ ) and the like.

Among these, those represented by the formula (I) are preferable from the viewpoint of increasing the charge amount, and CH ₃ (CH ₂ ) _n Si (OCH ₃ ) ₃ (where n = 5 to 19) is particularly preferable. For the same reason, R ₁ is preferably an alkyl group having 7 to 16 carbon atoms or a perfluoroalkyl group.

  The treatment with the coupling agent is preferable, for example, in the case where the spherical composite melamine resin particles are immersed in a solution containing the coupling agent and dried, so that a uniform coating can be formed. The adhesion amount of the coupling agent is preferably in the range of 0.1 to 25% by mass with respect to the spherical composite melamine resin particles.

Further, the surface of the spherical composite melamine resin particles themselves may be treated with silicone oil or the like. A known silicone oil can be used for the treatment, and it contains a dry method such as a spray dry method in which a treatment agent or a solution containing the treatment agent is sprayed on particles suspended in the gas phase, or a treatment agent. It can be processed by a wet method in which particles are immersed in a solution and dried.
By the method as described above, composite resin particles containing inorganic particles can be obtained.

  In FIG. 1, the cross section of an example of the produced composite resin particle is shown typically. In FIG. 1, 2 is a resin constituting the composite resin particle 1, and 3 is an inorganic particle. In the composite resin particles according to the present invention, the inorganic particles 3 may be uniformly dispersed or non-uniformly dispersed. According to the above-described manufacturing method, the composite resin particles 1 are as shown in FIG. In addition, the inorganic particles 3 are unevenly distributed near the surface of the composite resin particles 1.

  In the present invention, it is preferable that the inorganic particles 3 are partially exposed on the surface of the composite resin particles 1 as will be described later. For this purpose, in the production of the composite resin particles 1, the inorganic particles 3 can be added in a small amount. From the viewpoint of expressing the exposure of 3, the inorganic particles 3 are preferably unevenly distributed in the vicinity of the surface of the composite resin particle 1 as shown in FIG. 1.

  Here, the above “uneven distribution” means a range of 10% in the depth direction from the surface to the particle size of the composite resin particles 1 and a range of 40 to 100% of the inorganic particles 3 contained in the composite resin particles 22 (several ) Exists.

  According to the manufacturing method described above, the composite resin particles 1 including the inorganic particles 3 become spherical melamine resin particles in which the colloidal silica that is the inorganic particles 3 is unevenly distributed near the particle surface. The inorganic particles 3 are those embedded in the resin 2 near the surface of the composite resin particle as shown by 3a in FIG. 1 and those that are more than half exposed and fixed on the particle surface as shown in 3b. 3c There are those in which only a small portion as shown in FIG.

  Therefore, the composite resin particles 1 are roughly spherical, but the inorganic particles 3 are taken into the composite resin particles 1 while maintaining the shape as described above, and a part of the inorganic particles 3 is on the surface. Since some of them are exposed, the surface is in an uneven shape when viewed microscopically.

In the present invention, when the composite resin particle 1 is used as an external additive for the toner, the inorganic particle 3 can be effectively polished on the surface of the photoreceptor so that the inorganic particle 3 can be polished. It is preferable that a part of the surface is exposed.
Here, the “partially exposed” refers to the state of the inorganic particles 3 indicated by 3b and 3c in FIG.

  The shape of the composite resin particles in the present invention is not particularly limited, but is preferably a spherical shape as shown in FIG. 1 from the viewpoint of uniform dispersibility in the toner.

  In addition, for the purpose of improving the fluidity or chargeability of the toner, known fine powders such as inorganic fine powders such as silica, organic fine powders such as fatty acids or their derivatives or metal salts, fine powders of fluororesins, etc., are used together with the composite resin particles. A powder can also be used in combination.

Further, in order to control the fluidity and chargeability of the toner, it is necessary to sufficiently coat the surface of the toner particles. However, the composite resin particles alone may not provide a sufficient coating. Insofar as the effects are not impaired, it is preferable to use an inorganic compound in combination. In particular, when using composite resin particles having a large particle size, it is preferable to use an inorganic compound having a small particle size in combination as long as the effects of the present invention are not impaired. As the inorganic compound having a small particle size, an inorganic compound having a volume average particle size of 80 nm or less is preferable, and an inorganic compound having a size of 30 nm or less is more preferable.
As the inorganic compound having a small particle diameter, known compounds can be used, and examples thereof include silica, alumina, titania, calcium carbonate, magnesium carbonate, calcium phosphate, cerium oxide and the like. Further, a known surface treatment may be applied to the surface of these inorganic fine particles depending on the purpose. The addition amount of such an inorganic compound having a small particle diameter is preferably 0.3 to 3 parts by mass, and more preferably 0.5 to 2 parts by mass with respect to 100 parts by mass of the toner particles. When the addition amount is less than 0.3 parts by mass, the fluidity of the toner may not be sufficiently obtained, and blocking suppression due to heat storage tends to be insufficient. On the other hand, when the added amount is more than 3 parts by mass, an excessively coated state occurs, and the excess inorganic oxide may migrate to the contact member, causing secondary obstacles.

In the present invention, the composite resin particles are added to the toner particles and mixed. The mixing can be performed by a known mixer such as a V-type blender, a Henschel mixer, or a Redige mixer. At this time, various additives may be added as necessary.
Examples of these additives include other fluidizing agents, cleaning aids such as polystyrene fine particles, polymethyl methacrylate fine particles, and polyvinylidene fluoride fine particles, or transfer aids.

Further, as a method for external addition to the toner, either the composite resin particles are externally added alone, or the composite resin particles and other external additives are added and mixed simultaneously, or the composite resin particles are added and mixed first. Other external additives may be added and mixed, or the composite resin particles may be added and mixed after the other external additives are added and mixed first. When the composite resin particles and other external additives are used in combination, the composite resin particles are first mixed, and other inorganic oxide fine powders are added with weaker shear, thereby exhibiting the effects of the present invention more remarkably. can do.
Moreover, it does not matter even if it passes through a sieving process after external addition.

(toner)
The toner according to the present invention includes toner particles including at least a binder resin and a colorant and an external additive, and the external additive includes composite resin particles including the above-described inorganic particles.

  The toner used in the present invention is not particularly limited by its production method, and a known method can be used. Further, by using a toner having an average shape index SF1 in the range of 100 to 140, it is possible not only to obtain high development, transferability and high-quality images, but also to improve toner fluidity, and cleaning. After the toner is collected at the portion, the collected toner is preferably transported to a developing device, a toner replenishing portion, and the like.

  Further, the composite resin particles having a toner average shape factor SF1 in the range of 125 to 140, an average shape factor SF2 in the range of 105 to 130, and a volume average particle size of 0.08 to 0.30 μm as external additives. When used, it is possible to make the developer particularly excellent in transferability.

Here, the average shape factors SF1 and (2) are obtained by the following equations (1) and (2).
SF1 = (ML ² / A) × (π / 4) × 100 (1)
SF2 = (1 / 4π) × (I ² / A) × 100 (2)
In the above formulas (1) and (2), ML represents the absolute maximum length of the toner particles, A represents the projected area of the toner particles, and I represents the peripheral length of the toner particles. As a specific method for obtaining the average shape factor, a toner image is taken from an optical microscope into an image analyzer (LUZEX III, manufactured by Nireco Corporation), an equivalent circle diameter is measured, and the maximum length and area are calculated. A method for obtaining the values of the shape factors SF1 and SF2 of the above formulas for individual particles can be mentioned.

The toner content in the developer of the present invention is preferably 1% by mass to 20% by mass,
3 mass%-10 mass% are more preferable.

The method for producing the toner used in the present invention is not particularly limited by the production method as long as it satisfies the above shape factor and particle size, and a known method can be used.
For the production of the toner, for example, a binder resin, a colorant, a release agent, and, if necessary, a kneading and pulverizing method in which a charge control agent and the like are kneaded and pulverized and classified. A method of changing the shape by mechanical impact force or thermal energy, emulsion polymerization of a polymerizable monomer to obtain a binder resin, a formed resin dispersion, a colorant, a release agent, as required In accordance with this, an emulsion polymerization aggregation method for obtaining toner particles by mixing with a dispersion such as a charge control agent, and aggregating and heating and fusing, a polymerizable monomer and a colorant for obtaining a binder resin, and a release agent In addition, a suspension polymerization method in which a solution such as a charge control agent is suspended in an aqueous solvent for polymerization, if necessary, a binder resin, a colorant, a release agent, and a charge control agent as necessary. A solution suspension method in which a solution is suspended in an aqueous solvent and granulated can be used. In addition, a manufacturing method may be performed in which the toner particles obtained by the above method are used as a core, and fine particles are further adhered and heat-fused to have a core-shell structure.

  In the toner used in the present invention, when the internal additive is added to the inside of the toner particles by, for example, a kneading and pulverizing method, it is carried out by a kneading process. The kneading at this time can be performed using various heating kneaders. As the heat kneader, a three-roll type, a single screw type, a twin screw type, a Banbury mixer type, and the like are known.

  As described above, the production method of the toner used in the present invention is arbitrary, but in order to control the shape factor in the production process, for example, in the kneading and pulverization method, pulverization such as a collision plate type or a jet type is used. There is a choice of method. A device that causes toner to collide with an object such as a collision plate type is called a surface pulverization type, and examples of the device include a micronizer, ulmax, and a jet-o-mizer. A device that causes toners to collide with each other is called a volume grinding type, and examples of the device include KTM (krypton) and a turbo mill.

  Further, as a volume / surface grinding mold having a collision plate on the volume grinding mold and having both characteristics, there is an I-type Jet-Mill. In general, the pulverized product tends to be indeterminate in the volume pulverization type, and is more likely to be round in the surface pulverization type. Also, the shape changes depending on the number of classifications, and the more the number of classifications, the more likely it becomes round. Furthermore, the shape can be changed by adding a hybridization system (manufactured by Nara Machinery Co., Ltd.), mechano-fusion system (manufactured by Hosokawa Micron Corporation), kryptron system (manufactured by Kawasaki Heavy Industries, Ltd.), etc. Can also be mentioned.

As the binder resin used in the toner of the present invention, a conventionally known resin can be used. For example, a homopolymer or copolymer of one or more vinyl monomers is used.
Typical vinyl monomers include styrene, p-chlorostyrene, vinyl naphthalene; for example, ethylenically unsaturated monoolefins such as ethylene, propylene, butylene, isobutylene; for example, vinyl chloride, vinyl bromide, vinyl fluoride. Vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate, vinyl butyrate, vinyl formate, vinyl stearate, vinyl caproate; for example, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate , Ethylenic monocarboxylic acids such as dodecyl acrylate, n-octyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl-α-chloroacrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, and esters thereof For example, ethylenic monocarboxylic acid substitution products such as acrylonitrile, methacrylonitrile and acrylamide; for example, ethylenic carboxylic acids such as dimethyl maleate, diethyl maleate and dibutyl maleate and esters thereof; Vinyl ketones such as hexyl ketone and vinyl isopropenyl ketone; for example, vinyl ethers such as vinyl methyl ether, vinyl isobutyl ether and vinyl ethyl ether; for example, vinylidene halides such as vinylidene chloride and vinylidene chloride; N-vinyl compounds such as pyrrole, N-vinylcarbazole, N-vinylindole, N-vinylpyrrolidone and the like can be mentioned.

  Considering the fixing characteristics and storage stability of the toner, it is preferable to use a styrene-acrylic acid copolymer, a polyester resin, or a mixed system thereof among the binder resins.

  In addition, toner colorants include magnetic powders such as magnetite and ferrite, carbon black, aniline blue, caryl blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, and malachite green oxa. Rate, lamp black, rose bengal, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 57: 1, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 17, C.I. I. Pigment blue 15: 1, C.I. I. Pigment Blue 15: 3 can be exemplified as a representative one.

When the developer of the present invention is a developer containing a magnetic toner, the magnetic fine particles dispersed in the toner binder resin include known magnetic materials such as iron, cobalt, nickel, and the like. These alloys, FeSO ₄ , γ-Fe ₂ O ₃ , metal oxides such as cobalt-added iron oxide, various ferrites such as MnZn ferrite and NiZn ferrite, magnetite, hematite and the like can be used. What was processed with surface treating agents, such as a coupling agent and a titanate coupling agent, or what was polymer-coated, etc. are used. The mixing ratio of the magnetic fine particles is preferably in the range of 30 to 70% by mass, and more preferably in the range of 35 to 60% by mass with respect to the total mass of the toner. When the amount of magnetic fine particles is less than 30% by mass, the toner binding force by the magnet of the developer carrying member is reduced, and the toner is scattered or fogged. On the other hand, when it exceeds 70% by mass, the image density is lowered. The volume average particle size of the magnetic fine particles used for the internal addition of these toners is preferably about 0.05 to 0.35 μm from the viewpoint of dispersibility in the binder resin.

The toner used in the present invention preferably contains a release agent in order to improve the offset resistance.
As release agents, low molecular weight polyolefins such as polyethylene, polypropylene and polybutene; silicones having a softening point upon heating; fatty acid amides such as oleic acid amide, erucic acid amide, ricinoleic acid amide and stearic acid amide; carnauba Plant waxes such as wax, rice wax, candelilla wax, tree wax, jojoba oil; animal waxes such as beeswax; mineral and petroleum systems such as montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, Fischer-Tropsch wax Waxes; ester waxes of higher alcohols and higher alcohols such as stearyl stearate and behenyl behenate; butyl stearate, propyl oleate, glyceryl monostearate, glyceryl distearate Ester waxes of higher fatty acids such as Lido and pentaerythritol tetrabehenate and mono- or polyhydric lower alcohols; higher fatty acids such as diethylene glycol monostearate, dipropylene glycol distearate, distearic acid diglyceride, tetrastearic acid triglyceride And ester alcohols composed of polyhydric alcohol multimers; sorbitan higher fatty acid ester waxes such as sorbitan monostearate; and cholesterol higher fatty acid ester waxes such as cholesteryl stearate.

These release agents may be used alone or in combination of two or more.
The content of the release agent is preferably in the range of 1 to 30 parts by mass with respect to 100 parts by mass of the binder resin.

The volume average particle diameter of the toner used in the present invention is preferably in the range of 2 to 12 μm, and more preferably in the range of 3 to 7 μm. The volume average particle diameter can be measured with an aperture diameter of 50 μm using, for example, a Coulter counter [TA-II] type (manufactured by Coulter). At this time, the measurement is performed after the toner is dispersed in an electrolyte aqueous solution (Isoton aqueous solution) and dispersed by ultrasonic waves for 30 seconds or more. Moreover, it can measure with a Coulter multisizer, SLAD1100 (Shimadzu Corporation laser diffraction type particle size measuring apparatus), etc.

  In the present invention, a fatty acid metal salt may be used for the purpose of controlling the polishing amount and / or polishing uniformity of the photoreceptor. Examples of fatty acid metal salts include higher fatty acid metal salts. Specific examples of the higher fatty acid metal salt include zinc stearate, aluminum stearate, copper stearate, magnesium stearate, etc., zinc oleate, manganese oleate, iron oleate, copper oleate, oleic acid Licinol such as magnesium oleate such as magnesium, zinc palmitate, copper palmitate, magnesium palmitate, magnesium linoleate, zinc linoleate, zinc linoleate, zinc ricinoleate, lithium ricinoleate, etc. Examples include acid metal salts. Fatty acid calcium salts are particularly preferable from the viewpoint of preventing the cleaning blade from being worn and the photoreceptor from being worn.

The suitable manufacturing method of the said fatty-acid metal salt particle is demonstrated.
As raw materials for production, an aqueous solution or dispersion of an aqueous fatty acid salt solution (hereinafter also referred to as component (i)) and an inorganic metal salt (hereinafter also referred to as component (ii)) is used. Examples of the fatty acid salt used for preparing the aqueous fatty acid salt solution include alkali metal salts or ammonium salts of fatty acids having 4 to 30 carbon atoms. The fatty acid may be saturated or unsaturated, and may be linear or branched. Examples of such fatty acids include caprylic acid, capric acid, lauric acid, myristic acid, myristoleic acid, palmitic acid, isopalmitic acid, palmitoleic acid, stearic acid, behenic acid, lignoceric acid, serotic acid, montanic acid, Isostearic acid, oleic acid, arachic acid, ricinoleic acid, linolenic acid, alkali metal salts such as sodium and potassium such as behenic acid and erucic acid or ammonium salts, or beef fatty acid, soybean oil fatty acid, palm oil fatty acid And alkali metal salts or ammonium salts such as sodium and potassium of fatty acids derived from animal and vegetable oils and fats such as palm oil fatty acid.

  Among these, alkali metal salts such as sodium and potassium of fatty acids having 10 to 24 carbon atoms, particularly 12 to 22 carbon atoms, or ammonium salts are preferable. These fatty acids may be used alone or in combination of two or more. When an alkali metal salt or ammonium salt of a fatty acid having less than 4 carbon atoms is used, the resulting fatty acid metal salt has a high solubility in water, resulting in a decrease in yield. On the other hand, when an alkali metal salt or ammonium salt of a fatty acid having more than 30 carbon atoms is used, the solubility in water is too low, the aqueous solution concentration is lowered, and the production efficiency is lowered. The content of the alkali metal salt or ammonium salt of the fatty acid in the aqueous fatty acid salt solution is selected in the range of 0.001 to 2 mass%. If the content is less than 0.001% by mass, the amount of fatty acid metal salt obtained is significantly lower than the amount of the reaction solution, so that the production efficiency is poor and not practical. Moreover, when it exceeds 2 mass%, there exists a possibility that the average particle diameter of the fatty-acid metal salt particle obtained may become large. Considering the amount of the fatty acid metal salt to be obtained and the particle size thereof, the preferred content of the alkali metal salt or ammonium salt of the fatty acid in the aqueous solution is in the range of 0.5 to 1.5% by mass. Examples of inorganic metal salts used in the preparation of aqueous solutions or dispersions of inorganic metal salts used in the present invention include chlorides, sulfates, carbonates, nitrates or phosphorus of alkaline earth metals such as calcium, barium and magnesium. Acid salts, etc., or chlorides, sulfates, carbonates, nitrates or phosphates of metals such as titanium, zinc, copper, manganese, cadmium, mercury, zirconium, lead, iron, aluminum, cobalt, nickel, lithium and silver A salt etc. can be mentioned. These substances may be used alone or in combination of two or more. The content of the inorganic metal salt in the aqueous solution or dispersion of the inorganic metal salt is selected in the range of 0.001 to 2% by mass. If the content is less than 0.001% by mass, the amount of fatty acid metal salt obtained is significantly lower than the amount of the reaction solution, so that the production efficiency is poor and not practical. Moreover, when it exceeds 2 mass%, there exists a possibility that the average particle diameter of the fatty-acid metal salt particle obtained may become large. Considering the amount of the fatty acid metal salt to be obtained and the particle size thereof, the preferred content of the inorganic metal salt in the aqueous solution or dispersion is in the range of 0.01 to 1% by mass. There is no restriction | limiting in particular as water used for preparation of said (i) component and (ii) component, Although what is generally used may be used, like ion-exchange water, purified water, distilled water, etc. In addition, those having few impurities such as metal ions are preferable.

  The mixing ratio of the component (i) and the component (ii) is not particularly limited and may be appropriately selected depending on the situation, but is usually in the component (i) relative to the inorganic metal salt in the component (ii). It is preferable to select an equivalent ratio of the fatty acid salt of 0.9 to 11.1. When the equivalent ratio deviates from the above range, there are many unreacted raw materials, and the removal step may be necessary. In order to reduce residual impurities, the corresponding ratio is more preferably in the range of 0.95 to 1.05. As a production apparatus for the amount of fatty acid metal salt, a device capable of separately supplying the components (i) and (ii) into the mixer and mixing them is preferable. In particular, it is preferable that the component (i) and the component (ii) can be separately fed and mixed in the mixer as fast as possible. For example, it is advantageous to inject each raw material solution (or dispersion) into the mixer from different directions to mix each solution (or dispersion) and simultaneously discharge the mixture from the mixer. As these apparatuses, it is preferable to use a flow jet mixer, a line homogenizer, a sand mill or the like. Further, when the alkali metal salt or ammonium salt of the unreacted fatty acid remains after the reaction of the component (i) and the component (i), the component (i) and the component (ii) are discharged from the mixer. After that, an alkali metal salt or ammonium salt of a completely unreacted fatty acid can be reacted with a fatty acid metal salt by mixing an aqueous solution or dispersion containing 0.001 to 1.5% by mass of an inorganic metal salt. I can do it.

  The component (i) and the component (ii) are preferably mixed at a temperature lower than the crystal transition start temperature of the fatty acid metal salt to be produced, preferably at a temperature 5 ° C. lower than the crystal transition temperature. The fatty acid metal salt slurry thus obtained is separated into a fatty acid metal salt cake and a filtrate using a commonly used filtration device. The fatty acid metal cake is sufficiently washed with warm water or the like to remove impurities and then dried to obtain fatty acid metal salt fine particles. The drying treatment of the fatty acid metal cake is preferably at a temperature lower than the crystal transition start temperature of the obtained fatty acid metal salt, and more preferably at a temperature 5 ° C. lower than the crystal transition start temperature. The specific drying temperature varies depending on the type of fatty acid metal salt to be obtained. For example, in the case of zinc stearate, it is 100 ° C. or lower. When the drying treatment is performed at a temperature higher than the crystal transition start temperature of the fatty acid metal salt, aggregation of fine particles occurs, which may increase the average particle size. The drying process of the fatty acid metal salt cake may be performed at normal pressure, but in order to dry efficiently, the drying may be performed under reduced pressure or vacuum, or the fatty acid metal salt cake may be dried with a low boiling point solvent or the like. After the washing treatment, the obtained fatty acid metal salt cake may be dried. As the low boiling point solvent used at this time, those capable of efficiently removing water from the fatty acid metal salt are preferable, and examples thereof include methanol, ethanol, acetone, and methylene chloride.

  The water content in the fatty acid metal salt is preferably from 0.1 to 2.5 mass%, more preferably from 0.3 to 1.2 mass%, from the viewpoint of increasing the humidity stability of charging. When the amount of water exceeds 2.5% by mass, image blurring under high temperature and high humidity tends to occur. The amount of free fatty acid in the fatty acid metal salt is preferably 0.01 to 0.7% by mass, and more preferably 0.05 to 0.5% by mass. When it exceeds 0.7 mass%, charging members such as a carrier and a developing roll are contaminated. If it is less than 0.01% by mass, the cleaning blade wear tends to increase rather, and the life of the cleaning blade may be shortened.

  In addition, a charge control agent may be added to the toner in the present invention as necessary. Known charge control agents can be used, but azo metal complex compounds, metal complex compounds of salicylic acid, and resin type charge control agents containing polar groups can be used. When the toner is manufactured by a wet manufacturing method, it is preferable to use a material that is difficult to dissolve in water in terms of controlling ionic strength and reducing wastewater contamination.

(Career)
On the other hand, the carrier in the present invention is not particularly limited, but a resin-coated carrier having a resin coating layer on the core surface is preferably used. Preferably, a conductive material is dispersed and contained in the resin coating layer. When the spherical toner is used, the packing property is inevitably improved at the conveyance restriction portion in the developing device, and accordingly, a strong force is applied not only to the toner surface but also to the carrier. Therefore, by dispersing and containing a conductive material in the resin coating layer of the carrier, even if the resin coating layer is peeled off, the volume specific resistance of the carrier is not greatly changed, and as a result, high image quality can be maintained over a long period of time. This is because it can be made possible.

  As matrix resin used for the resin coating layer, polyethylene, polypropylene, polystyrene, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, Styrene-acrylic acid copolymer, straight silicone resin composed of organosiloxane bond or its modified product, fluorine resin, polyester, polyurethane, polycarbonate, phenol resin, amino resin, melamine resin, benzoguanamine resin, urea resin, amide resin, epoxy resin However, the present invention is not limited to these examples. Examples of the conductive material include metals such as gold, silver and copper, and titanium oxide, zinc oxide, barium sulfate, aluminum borate, potassium titanate, tin oxide, and carbon black. Is not to be done.

Examples of the conductive material contained in the resin coating layer include metals such as gold, silver, and copper, and titanium oxide, zinc oxide, barium sulfate, aluminum borate, potassium titanate, tin oxide, and carbon black. However, it is not limited to these.
The content of the conductive material is preferably in the range of 1 to 50 parts by mass and more preferably in the range of 3 to 20 parts by mass with respect to 100 parts by mass of the coating resin.

Examples of the carrier core material include magnetic metals such as iron, nickel and cobalt, magnetic oxides such as ferrite and magnetite, and glass beads. However, in order to adjust the volume resistivity using the magnetic brush method, a magnetic material is used. Preferably there is.
The volume average particle diameter of the core material is generally 10 to 500 μm, preferably 30 to 100 μm.

  As a method for forming the resin coating layer on the surface of the core material of the carrier, an immersion method in which the core material is immersed in a coating layer forming solution containing a matrix resin, a solvent, and, if necessary, a conductive material, for coating layer formation. Spray method of spraying the solution onto the surface of the carrier core material, fluidized bed method of spraying the coating layer forming solution in a state where the carrier core material is suspended by flowing air, carrier core material and coating layer forming solution in a kneader coater The kneader coater method which mixes and removes a solvent is mentioned.

  The solvent used in the coating layer forming solution is not particularly limited as long as it dissolves the matrix resin. For example, aromatic hydrocarbons such as toluene and xylene, and ketones such as acetone and methyl ethyl ketone. , Ethers such as tetrahydrofuran and dioxane can be used.

  The average film thickness of the resin coating layer is usually 0.1 to 10 μm, but in the present invention, it is preferably in the range of 0.5 to 3 μm in order to develop a stable volume resistivity of the carrier over time. .

The volume resistivity of the carrier formed as described above is 10 ⁶ to 10 ¹⁴ in the range of 10 ³ to 10 ⁴ V / cm corresponding to the upper and lower limits of a normal development contrast potential in order to achieve high image quality. It is preferably Ωcm. If the volume specific resistance of the carrier is less than 10 ⁶ Ωcm, the reproducibility of fine lines is poor, and toner fog is likely to occur on the background due to charge injection. Further, if the volume resistivity of the carrier is larger than 10 ¹⁴ Ωcm, reproduction of black solid and halftone becomes worse. In addition, the amount of carriers transferred to the photoconductor increases, and the photoconductor is easily damaged.

[Image forming method]
A charging unit that uniformly charges the electrostatic latent image carrier, a latent image forming unit that forms an electrostatic latent image by exposing the surface of the charged electrostatic latent image carrier, and the electrostatic latent image includes toner. An image forming apparatus including a developing unit that develops a toner image using a developer, a transfer unit that transfers the formed toner image to a recording material, and a fixing unit that fixes the transferred toner image on the surface of the recording material is used. In this image forming method, the developer is the developer of the present invention described above, and the transfer means develops each color toner on a latent image carrier and transfers it to an intermediate transfer member. After that, it is a transfer means for transferring each color toner to a recording material at a time.
In full color image formation in the above image forming method, from the viewpoint of paper versatility and high image quality, each color toner image is once transferred and laminated on the surface of an intermediate transfer belt or intermediate transfer drum as an intermediate transfer member, The laminated color toner images are transferred onto the surface of a recording material such as paper at a time.
Note that the image forming method of the present invention does not include a mode in which toner recycling is performed.

  The image forming apparatus includes, in particular, the latent image carrier, charging means for charging the surface of the latent image carrier, and latent image forming means for forming a latent image on the surface of the charged latent image carrier. A tandem type image forming apparatus preferably includes a plurality of developing means for developing the electrostatic latent image using toner and a transfer means for transferring the toner image to an intermediate transfer member.

The image forming method to which the developer of the present invention is applied includes a charging means for uniformly charging the latent image carrier, and a latent image for forming an electrostatic latent image by exposing the surface of the charged latent image carrier. Forming means, developing means for developing the electrostatic latent image into a toner image using a developer containing toner, transfer for transferring the formed toner image to an intermediate transfer member, and transferring the toner image to a recording material and fixing at the same time An image forming method for forming an image using an image forming apparatus including a fixing unit, wherein the developer is the developer of the present invention, and the transfer fixing unit develops each color toner on a latent image carrier. In addition, it is also possible to adopt a mode in which after transferring to the intermediate transfer member, each color is transferred to the recording material at a time and fixed simultaneously.
That is, when the developer of the present invention described above is used, a high-quality image can be obtained particularly in a full-color image even when image formation is performed using the image forming apparatus having the transfer fixing unit. .

  The intermediate transfer body in the transfer step is to transport an unfixed toner image to a predetermined toner image transfer fixing position while holding an unfixed toner image. Specifically, it has a two-layer structure consisting of a base layer and a surface layer. Is preferably used. As the base layer, a resin film containing a conductive filler such as carbon black or metal oxide can be used to control the resistance low. For the surface layer, it is preferable to use a film made of a material having a low surface energy in order to increase the releasability of the toner. It is important that any material is a heat-resistant film, and PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer), PTFE (polytetrafluoroethylene), polyimide, silicone-based films, etc. may be used. it can. However, it is not limited to these.

  The transfer fixing in the transfer fixing unit is performed at least by heating, but is preferably performed by heating and pressing. Specifically, for example, a predetermined recording material is overlapped so as to sandwich the toner image on the intermediate transfer member, and the superimposed intermediate transfer member, toner image, and recording material are sandwiched and heated and pressed. It is preferable to use a pair of heating and pressing members. As the heating and pressing member, a roll in which a heat-resistant elastic layer such as silicone rubber is formed on the surface of a metal roll such as iron, stainless steel, copper, or aluminum, and a heat source such as a halogen lamp included can be used. The heating / pressurizing member is not limited to a roll, and may be of any configuration as long as it can uniformly pressurize without causing floating or displacement between the intermediate transfer member and the recording material. But you can. For example, a combination of one heating and pressing roll and one fixed pad, or a set of fixed pads may be used.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto. In the description of the toner and the carrier, “part” means “part by mass” unless otherwise specified.

First, the toner, carrier, and developer used in Examples and Comparative Examples will be described.
<Each measurement method>
In the production of the following toner, carrier and developer, each measurement was performed by the following method.

-Specific gravity measurement of external additives-
The specific gravity was measured according to JIS-K-0061 5-2-1 using a Le Chatelier specific gravity bottle. The operation was performed as follows.
(1) About 250 ml of ethyl alcohol is put into a Lechatelier specific gravity bottle and adjusted so that the meniscus is at the position of the scale.
(2) The specific gravity bottle is immersed in a constant temperature water bath, and when the liquid temperature reaches 20.0 ± 0.2 ° C., the position of the meniscus is accurately read with the scale of the specific gravity bottle. (Accuracy 0.025ml)
(3) About 100.000 g of a sample is weighed and its mass is designated as W.
(4) Put the weighed sample in a specific gravity bottle to remove bubbles.
(5) The specific gravity bottle is immersed in a constant temperature water bath, and when the liquid temperature becomes 20.0 ± 0.2 ° C., the position of the meniscus is accurately read with the scale of the specific gravity bottle. (Accuracy 0.025ml)
(6) The specific gravity is calculated by the following formulas (3) and (4).
D = W / (L2-L1) Formula (3)
S = D / 0.9982 ... Formula (4)
In the formula, D is the density of the sample (20 ° C.) (g / cm ³ ), S is the specific gravity of the sample (20 ° C.), W is the apparent mass of the sample (g), and L1 is before the sample is placed in the specific gravity bottle. Meniscus reading (20 ° C.) (ml), L2 is the meniscus reading (20 ° C.) (ml) after placing the sample in the density bottle, 0.9982 is the density of water at 20 ° C. (g / cm ³ ) is there.

-Measurement of volume average particle size and number average particle size of external additives-
A laser diffraction / scattering particle size distribution analyzer [Mastersizer 2000 (trade name), manufactured by Malvern Co., Ltd.] was used.

-Resistance measurement-
As shown in FIG. 2, the measurement sample 13 is sandwiched between the lower electrode 14 and the upper electrode 12 with a thickness H, and the thickness is measured with a dial gauge while pressing from above, and the electrical resistance of the measurement sample 13 is measured with a high voltage ohmmeter. 15 was measured. Specifically, a measurement disk was prepared by applying a pressure of 500 kg / cm ^{2 to} a specific titanium oxide sample with a molding machine. Next, the surface of the disk was cleaned with a brush, sandwiched between the upper electrode 12 and the lower electrode 14 in the cell, and the thickness was measured with a dial gauge. Next, a voltage was applied and the current value was read to determine the volume resistivity.
Further, a carrier sample was filled in a lower electrode 14 of 100φ, the upper electrode 12 was set, a load of 3.43 kg was applied from above, and the thickness was measured with a dial gauge. Next, a voltage was applied and the current value was read to determine the volume resistivity.

-Toner shape factors SF1, SF2-
In the present invention, the average shape factors SF1 and SF2 of the toner mean the average value of values calculated by the following formula for individual toner particles. In the case of a true sphere, SF1 = 100.
SF1 = (ML ² / A) × (π / 4) × 100 (1)
SF2 = (1 / 4π) × (I ² / A) × 100 (2)
In formulas (1) and (2), ML represents the absolute maximum length of the toner particles, A represents the projected area of the toner particles, and I represents the peripheral length of the toner particles.
As a specific method for obtaining the average shape factor, a toner image is taken from an optical microscope into an image analyzer (LUZEX III, manufactured by Nireco Corporation), an equivalent circle diameter is measured, and the maximum length and area are calculated. The values of the shape factors SF1 and SF2 of the above formula are obtained for each particle.

-Measurement of charge amount-
(1) The charge amount at high temperature and high humidity and low temperature and low humidity is as follows: high temperature and high humidity: 28 ° C., 80% RH, low temperature and low humidity: 10 ° C., 15% RH. The developer was stirred for 30 minutes, and the stirred developer was measured with a TB200 manufactured by Toshiba under the conditions of 25 ° C. and 55% RH.
(2) The amount of charge in the actual machine evaluation test was measured with a TB200 manufactured by Toshiba under the conditions of 25 ° C. and 55% RH in the same manner as above by collecting the developer on the mag sleeve in the developing device.

-Image density (Solid Area Density)-
The image density was measured using X-Rite 404A (X-Rite).

[Production of composite resin particles]
<Composite resin particle A>
In a 2 L reaction flask equipped with a stirrer, a reflux condenser and a thermometer, 50.0 parts of melamine, 96.5 parts of 37% formalin, aqueous silica sol [manufactured by Nissan Chemical Industries, Snowtex S (trade name): SiO ₂ concentration 30.5% by mass, pH 10.0, average particle diameter 7.9 nm] 20.7 parts and 720 parts of water were charged, and the pH was adjusted to 8.7 with 25% aqueous ammonia.

  Next, the temperature of the mixture was increased while stirring, and the temperature was maintained at 70 ° C. and reacted for 30 minutes to prepare an aqueous solution of an initial condensate of melamine resin. Next, while maintaining the temperature at 70 ° C., a 10% by mass aqueous solution of dodecylbenzenesulfonic acid was added to the obtained aqueous solution of the initial condensate to adjust the pH to 7.0. After about 20 minutes, the reaction system became cloudy and cured melamine resin particles were precipitated. Thereafter, the temperature was raised to 90 ° C. and the curing reaction was continued for 3 hours. After cooling, the resulting reaction solution was filtered and dried to obtain white composite resin particles A.

The volume average particle size of the obtained composite resin particles A was 0.3 μm as measured by a laser diffraction / scattering particle size distribution analyzer [Mastersizer 2000 (trade name), manufactured by Malvern, Inc.]. The number average particle diameter d ₅₀ is 0.27 μm, the proportion of fine particles having a particle size of 1/2 × d ₅₀ or less is 5%, and the proportion of fine particles having a particle size of 2 × d ₅₀ or more is 15%. Number%.

  The cured melamine resin particles (composite resin particles A) are observed as they are with a scanning electron microscope (SEM), and in the state of slice pieces, transmission electron microscope-energy-dispersive X-ray analysis (TEM-EDX) ), It was confirmed that the particles were spherical and the colloidal silica was unevenly distributed near the particle surface.

<Composite resin particle B>
In a 2 L reaction flask equipped with a stirrer, a reflux condenser and a thermometer, 50.0 parts of melamine, 96.5 parts of 37% formalin, aqueous silica sol [manufactured by Nissan Chemical Industries, Snowtex S (trade name): 35.7 parts of SiO ₂ concentration 30.5% by mass, pH 10.0, average particle diameter 7.9 nm] and 920 parts of water were charged, and the pH was adjusted to 8.5 with 25% aqueous ammonia. Thereafter, the temperature of the mixture was increased while stirring, the temperature was kept at 70 ° C., and the mixture was reacted for 30 minutes to prepare an aqueous solution of an initial condensate of melamine resin.

  Next, while maintaining the temperature at 70 ° C., a 10% by mass aqueous solution of dodecylbenzenesulfonic acid was added to the aqueous solution of the obtained initial condensate to adjust the pH to 7.0. About 25 minutes later, the reaction system became clouded and cured melamine resin particles were precipitated. Thereafter, the temperature was raised to 90 ° C. and the curing reaction was continued for 3 hours. After cooling, the resulting reaction solution was filtered and dried to obtain white composite resin particles B.

The volume average particle diameter of the obtained composite resin particles B was 0.15 μm as measured by a laser diffraction / scattering particle size distribution measuring apparatus [Mastersizer 2000 (trade name) manufactured by Malvern, Inc.]. The number average particle diameter d ₅₀ is 0.13 μm, the proportion of fine particles having a particle size of 1/2 × d ₅₀ or less is 10%, and the proportion of fine particles having a particle size of 2 × d ₅₀ or more is 7%. Number%. The cured melamine resin particles were observed as they were with a scanning electron microscope (SEM), and observed with a transmission electron microscope-energy-dispersive X-ray analysis (TEM-EDX) in a sliced state. The particles were spherical, and it was confirmed that colloidal silica was unevenly distributed near the particle surface.

<Composite resin particle C>
In a 2 L reaction flask equipped with a stirrer, a reflux condenser and a thermometer, 50.0 parts of melamine, 96.5 parts of 37% formalin, aqueous silica sol [manufactured by Nissan Chemical Industries, Snowtex S (trade name): The SiO ₂ concentration was 30.5% by mass, pH 10.0, average particle diameter 7.9 nm] 133.5 parts and water 1820 parts were charged, and the pH was adjusted to 8.5 with 25% aqueous ammonia. Thereafter, the temperature of the mixture was increased while stirring, the temperature was kept at 70 ° C., and the mixture was reacted for 30 minutes to prepare an aqueous solution of an initial condensate of melamine resin.

  Next, while maintaining the temperature at 70 ° C., a 10% by mass aqueous solution of dodecylbenzenesulfonic acid was added to the aqueous solution of the obtained initial condensate to adjust the pH to 7.0. About 25 minutes later, the reaction system became clouded and cured melamine resin particles were precipitated. Thereafter, the temperature was raised to 90 ° C. and the curing reaction was continued for 3 hours. After cooling, the resulting reaction solution was filtered and dried to obtain white composite resin particles C.

The volume average particle diameter of the obtained composite resin particles C was 0.05 μm as measured with a laser diffraction / scattering particle size distribution measuring apparatus [Mastersizer 2000 (trade name) manufactured by Malvern, Inc.]. The number average particle diameter d ₅₀ is 0.03 μm, the proportion of fine particles having a particle size of 1/2 × d ₅₀ or less is 15% by number, and the proportion of fine particles having a particle size of 2 × d ₅₀ or more is 10%. Number%.

  The cured melamine resin particles were observed as they were with a scanning electron microscope (SEM), and observed with a transmission electron microscope-energy-dispersive X-ray analysis (TEM-EDX) in a sliced state. The particles were spherical, and it was confirmed that colloidal silica was unevenly distributed near the particle surface.

<Composite resin particle D>
Into a 1 L beaker, 500 parts of methanol and 10 parts of methyltriethoxysilane were added, and further 100 parts of spherical composite cured resin particles A were added and stirred. After the methanol was distilled off with an evaporator, The composite resin particles D subjected to hydrophobic treatment by heating for a time were obtained.

The volume average particle size of the obtained composite resin particles D was 0.3 μm as measured by a laser diffraction / scattering particle size distribution measuring apparatus [Mastersizer 2000 (trade name) manufactured by Malvern, Inc.]. The number average particle diameter d ₅₀ is 0.27 μm, and the proportion of fine particles having a particle size of ½ × d ₅₀ or less is 4% by number, and the proportion of fine particles having a particle size of 2 × d ₅₀ or more. 18% by number.

<Manufacture of toner particles A>
Styrene-n-butyl acrylate resin 100 parts (Tg = 58 ° C., Mn = 4000, Mw = 25000)
・ Carbon black 3 parts (Mogal L: Cabot)
The above mixture was kneaded with an extruder, pulverized with a jet mill, and then dispersed with a wind classifier to obtain a black toner A having D ₅₀ = 5.0 μm, SF1 = 145, and SF2 = 119.

<Manufacture of toner particles B>
-Adjustment of resin dispersion (1)-
・ Styrene 370 parts ・ N-butyl acrylate 30 parts ・ Acrylic acid 8 parts ・ Dodecanethiol 24 parts ・ Carbon tetrabromide 4 parts

  6 parts of nonionic surfactant (Nonipol 400: manufactured by Sanyo Chemical Co., Ltd.) and anionic surfactant (Neogen SC: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 10 parts dissolved in 550 parts of ion-exchanged water was emulsified and dispersed in a flask, and 50 parts of ion-exchanged water in which 4 parts of ammonium persulfate was dissolved was added thereto while slowly mixing for 10 minutes. After carrying out nitrogen substitution, the inside of the flask was stirred and heated in an oil bath until the contents reached 70 ° C., and emulsion polymerization was continued for 5 hours. As a result, a resin dispersion liquid (1) in which resin particles of 155 nm, Tg = 59 ° C., and weight average molecular weight Mw = 12000 were dispersed was obtained.

-Adjustment of resin dispersion (2)-
・ Styrene 280 parts ・ n-butyl acrylate 120 parts ・ acrylic acid 8 parts

6 parts of nonionic surfactant (Nonipol 400: manufactured by Sanyo Chemical Co., Ltd.) and anionic surfactant (Neogen SC: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 12 parts dissolved in 550 parts of ion-exchanged water was emulsified and dispersed in a flask. While slowly mixing for 10 minutes, 50 parts of ion-exchanged water in which 3 parts of ammonium persulfate was dissolved was added thereto. After carrying out nitrogen substitution, the inside of the flask was stirred and heated in an oil bath until the contents reached 70 ° C., and emulsion polymerization was continued for 5 hours.
As a result, a resin dispersion liquid (2) in which resin particles of 105 nm, Tg = 53 ° C., and weight average molecular weight Mw = 550000 were dispersed was obtained.

-Preparation of colored dispersion (1)-
・ 50 parts of carbon black (Mogal L: Cabot)
・ Nonionic surfactant 5 parts (Nonipol 400: Sanyo Chemical Co., Ltd.)
・ 200 parts of ion exchange water

  A colored dispersant in which the above components are mixed, dissolved and dispersed for 10 minutes using a homogenizer (Ultra Turrax T50: manufactured by IKA), and colorant (carbon black) particles having an average particle size of 250 nm are dispersed. (1) was adjusted.

-Adjustment of colored dispersion (2)-
Cyan pigment (Pigment Blue 15: 3) 70 parts Nonionic surfactant 5 parts (Nonipol 400: manufactured by Sanyo Chemical Co., Ltd.)
-Ion-exchanged water Mixing 200 parts or more of components, dissolving, dispersing for 10 minutes using a homogenizer (Ultra Turrax T50: manufactured by IKA), colorant (Cyan pigment) particles having an average particle size of 250 nm Dispersed colored dispersant (2) was prepared.

-Preparation of colored dispersion (3)-
-Magenta pigment (Pigment Red122) 70 parts-Nonionic surfactant 5 parts (Nonipol 400: manufactured by Sanyo Chemical Co., Ltd.)
・ 200 parts of ion exchange water

  A color dispersant in which the above components are mixed, dissolved, and dispersed for 10 minutes using a homogenizer (Ultra Turrax T50: manufactured by IKA) to disperse colorant (Magenta pigment) particles having an average particle diameter of 250 nm. (2) was adjusted.

-Preparation of colored dispersion (4)-
Yellow pigment (Pigment Yellowpow 180) 100 parts Nonionic surfactant 5 parts (Nonipol 400: manufactured by Sanyo Chemical Co., Ltd.)
・ 200 parts of ion exchange water

  A coloring dispersant in which the above components are mixed, dissolved and dispersed for 10 minutes using a homogenizer (Ultra Turrax T50: manufactured by IKA), and colorant (Yellow pigment) particles having an average particle size of 250 nm are dispersed. (4) was adjusted.

-Adjustment of release agent dispersion-
・ 50 parts of paraffin wax (HNP0190: manufactured by Nippon Seiwa Co., Ltd., melting point 85 ° C.)
Cationic surfactant 5 parts (Sanisol B50: manufactured by Kao Corporation)

  The above components were dispersed in a round stainless steel flask using a homogenizer (Ultra Turrax T50: manufactured by IKA) for 10 minutes, and then dispersed with a pressure discharge type homogenizer, so that the average particle size was 550 nm. A release agent dispersion (1) in which the mold agent particles were dispersed was prepared.

-Adjustment of aggregated particles-
Resin dispersion (1) 120 parts Resin dispersion (2) 80 parts Colorant dispersion 200 parts Release agent dispersion (1) 40 parts Cationic surfactant 1.5 parts (Sanisol B50: (Kao Corporation)

  The above components were mixed and dispersed in a round stainless steel flask using a homogenizer (Ultra Turrax T50: manufactured by IKA), and then heated to 50 ° C. while stirring the inside of the flask in an oil bath for heating. . After maintaining at 45 ° C. for 20 minutes, it was confirmed with an optical microscope that it was confirmed that aggregated particles having an average particle diameter of about 5.0 μm were formed. Further, 60 parts of the resin dispersion (1) as a resin-containing fine particle dispersion was gently added to the dispersion. The temperature of the heating oil bath was raised to 50 ° C. and held for 30 minutes. When observed with an optical microscope, it was confirmed that adhered particles having an average particle diameter of about 5.6 μm were formed.

-Production of toner particles B-
After adding 3 parts of an anionic surfactant (Neogen SC: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) to the particle dispersion, the inside of the stainless steel flask is sealed and stirred at 105 ° C. using a magnetic seal. And heated for 4 hours.
Then, after cooling, the reaction product was filtered, washed thoroughly with ion-exchanged water, and then dried to obtain electrostatic image developing toner particles.
By changing the colorant dispersion in accordance with the method for preparing toner particles B described above, toner particles B of Kuro, Cyan, Magenta, and Yellow were prepared ((1) to (4) below).

(1) Toner particle B (Kuro)
Colorant dispersion in the method using a (1), SF1 = 128, SF2 = 107, was obtained Kuro toner particle size D ₅₀ = 5.8 [mu] m.

(2) Toner particle B (Cyan)
A cyan toner having SF1 = 130, SF2 = 106, particle size D ₅₀ = 5.6 μm was obtained by the above method using the colorant dispersion (2).

(3) Toner particle B (Magenta)
A Magenta toner having SF1 = 135, SF2 = 115, and particle size D50 = 5.5 μm was obtained by the above method using the colorant dispersion (3).

(4) Toner particle B (Yellow)
The yellow toner having SF1 = 127, SF2 = 106, and particle size D50 = 5.9 μm was obtained by the above method using the colorant dispersion (4).

<Creation of carrier>
・ Ferrite particles (average particle size: 50 μm) 100 parts ・ Toluene 14 parts ・ Styrene-methacrylate copolymer (component ratio: 90/10) 2 parts ・ Carbon black (R330: manufactured by Cabot Corporation) 0.2 part

First, the above components except for ferrite particles are stirred with a stirrer for 10 minutes to prepare a dispersed coating solution. Next, the coating solution and ferrite particles are placed in a vacuum degassing kneader and stirred at 60 ° C. for 30 minutes. Then, the carrier was obtained by further depressurizing and degassing while heating and drying. This carrier had a volume resistivity of 10 ¹¹ Ωcm when an applied electric field of 1000 V / cm was applied.

(Example 1)
100 parts of each of Kuro, Cyan, Magenta, and Yellow toners of toner particles B, 1 part of hydrophobic silicon oxide having a volume average particle diameter of 7 nm (RX300, manufactured by Nippon Aerosil Co., Ltd.), and hydrophobic silicon oxide having a volume average particle diameter of 40 nm (RX50, manufactured by Nippon Aerosil Co., Ltd.) 1.5 parts, 0.5 parts of composite resin particles A were added, blended using a Henschel mixer for a peripheral speed of 32 m / s * 10 minutes, and then coarse particles using a 45 μm mesh sieve. Then, a toner was obtained. 100 parts of a carrier and 5 parts of the toner were stirred at 40 rpm for 20 minutes using a V-blender, and sieved with a sieve having a 177 μm mesh to obtain a developer.

(Example 2)
100 parts of the toner particles B (Kuro), 1 part of hydrophobic titanium oxide (T805, manufactured by Nippon Aerosil Co., Ltd.) having a volume average particle diameter of 21 nm, and hydrophobic silicon oxide (RY50, manufactured by Nippon Aerosil Co., Ltd.) having a volume average particle diameter of 40 nm 1.5 parts and 0.6 parts of composite resin particles B were added, blended using a Henschel mixer for a peripheral speed of 32 m / s * 10 minutes, and then coarse particles were removed using a 45 μm mesh sieve to obtain a toner. . 100 parts of a carrier and 5 parts of the toner were stirred at 40 rpm for 20 minutes using a V-blender, and sieved with a sieve having a 177 μm mesh to obtain a developer.

(Example 3)
To 100 parts of the toner particles B (Kuro), 0.7 parts of composite resin particles C are added, blended using a Henschel mixer for a peripheral speed of 32 m / s * 10 minutes, and then a hydrophobic silicon oxide (volume average particle diameter of 7 nm) RX300 (manufactured by Nippon Aerosil Co., Ltd.) 1 part, hydrophobic silicon oxide having a volume average particle size of 40 nm (RX50, manufactured by Nippon Aerosil Co., Ltd.) 1.5 parts, blended at a peripheral speed of 20 m / s * 5 minutes, and a 45 μm mesh Coarse particles were removed using a sieve to obtain a toner. 100 parts of a carrier and 5 parts of the toner were stirred at 40 rpm for 20 minutes using a V-blender, and sieved with a sieve having a 177 μm mesh to obtain a developer.

Example 4
100 parts of the toner particles B (Kuro), 1 part of hydrophobic titanium oxide (T805, manufactured by Nippon Aerosil Co., Ltd.) having a volume average particle diameter of 21 nm, and hydrophobic silicon oxide (RX50, manufactured by Nippon Aerosil Co., Ltd.) having a volume average particle diameter of 40 nm 1.5 parts and 0.5 parts of composite resin particles D were added, blended for 10 minutes at a peripheral speed of 32 m / s * 10 minutes using a Henschel mixer, and then coarse particles were removed using a 45 μm mesh sieve to obtain a toner. . 100 parts of a carrier and 5 parts of the toner were stirred at 40 rpm for 20 minutes using a V-blender, and sieved with a sieve having a 177 μm mesh to obtain a developer.

(Example 5)
To 100 parts of the toner particles A, 1 part of hydrophobic silicon oxide (RX300, manufactured by Nippon Aerosil Co., Ltd.) having a volume average particle diameter of 7 nm and 0.3 parts of composite resin particles A are added, and the peripheral speed is 32 m / s * 10 minutes using a Henschel mixer. After blending, coarse particles were removed using a 45 μm mesh sieve to obtain a toner. 100 parts of a carrier and 5 parts of the toner were stirred at 40 rpm for 20 minutes using a V-blender, and sieved with a sieve having a 177 μm mesh to obtain a developer.

(Comparative Example 1)
In Example 1, instead of the composite resin particles A externally added to the toner particles, 0.5 parts of melamine resin particles (Epester S: manufactured by Nippon Shokubai Co., Ltd.) having a volume average particle size of 0.3 μm were used. Was obtained in the same manner as in Example 1.

(Comparative Example 2)
A developer was obtained in the same manner as in Example 1 except that the composite resin particles A externally added to the toner particles were not used.

(Comparative Example 3)
In Example 1, in place of the composite resin particles A externally added to the toner particles, 0.5 parts of spherical PMMA particles having a volume average particle size of 0.3 μm were used, and the same procedure as in Example 1 was performed. A developer was obtained.

(Comparative Example 4)
In Example 1, in place of the composite resin particles A externally added to the toner particles, 0.5 parts of amorphous alumina particles having a volume average particle size of 0.3 μm were used. To obtain a developer.

<Environmental dependency test>
The developers obtained in Examples 1 to 5 and Comparative Examples 1 to 4 were applied to a Docu Centra Color 500 developing machine manufactured by Fuji Xerox, and high temperature and high humidity (28 ° C., 80 RH%) and low temperature and low humidity (10 ° C., 15 RH). %) Were left for a whole day and night, and then idled for 30 minutes in each environment to evaluate the charge of the developer.

The charge evaluation was performed by the blow-off method. In the blow-off method, 0.5 part of a sample is placed in a 30-ml metal gauge with a mesh opening of 18 μm at the top and bottom and blown off in nitrogen gas at 3 atm for 30 seconds. Measured by Keisley, 6517A) and calculated by the following equation.
Charge amount = measured charge value / [(gauge mass before blow-off) − (gauge mass after blow-off)]

In addition, the said chargeability evaluation was performed in accordance with the following criteria.
-Electric charge evaluation criteria-
○: Good △: Some environmental dependence was observed ×: Poor The results are shown in Table 1.

As is clear from the results shown in Table 1, Examples 1 to 5 had very good chargeability at high temperature and high humidity and low temperature and low humidity, and also had excellent environmental stability.
On the other hand, the developer of Comparative Example 1 had a low problem of environmental dependency due to low charge amount at high temperature and high humidity. Although the developers of Comparative Examples 2, 3, and 4 have good chargeability and high environmental stability at high temperature and high humidity and low temperature and low humidity, there are problems in charge maintenance and image maintenance as described below.

<Evaluation of initial developability>
TC5% developer is allowed to stand overnight at a specified temperature and humidity (29 ° C 90%, 10 ° C 20%), and an image with two 2cm x 5cm patches is copied, and the development amount is measured with a hard stop. It was measured. The developed portions at two places on the photosensitive member were transferred onto the tape using adhesiveness, the toner-attached tape mass was measured, and the developed amount was obtained by subtracting the tape mass and averaging. A preferred value is 4.0 to 5.0 g / m ² .

<Evaluation of developability after 20,000 sheets>
With the obtained developer, 20,000 copies were taken under a predetermined temperature and humidity (29 ° C. 90%, 10 ° C. 20%), and further left to stand for an image having two 2 cm × 5 cm patches. A copy was made and the amount of development was measured with a hard stop. The developed portions at two places on the photosensitive member were transferred onto the tape using adhesiveness, the toner-attached tape mass was measured, and the developed amount was obtained by subtracting the tape mass and averaging.

<Evaluation of fogging at the initial stage and after 20,000 sheets>
Similarly, the background portion was transferred onto a tape, and the number of toners per 1 cm ² was counted, and 100 or less was evaluated as ◯, 100 to 500 was evaluated as Δ, and the case where it was larger was evaluated as ×.

<Measurement of charge amount at the initial stage and after 20,000 sheets>
At the initial stage and after copying 20,000 sheets, the developer on the mag sleeve in the developing unit was collected, and the charge amount was measured with a TB200 manufactured by Toshiba under the conditions of 25 ° C. and 55% RH.

<Evaluation of transferability at initial stage and after 20,000 sheets>
At the end of the transfer process, a hard stop is performed, the toner mass on the two intermediate transfer members is transferred onto the tape in the same manner as described above, the toner adhering tape mass is measured, and the tape mass is subtracted and then averaged. a was obtained, and similarly, the toner amount b remaining on the photoreceptor was obtained, and the transfer efficiency was obtained by the following equation.
Transfer efficiency η (%) = a × 100 / (a + b)
Preferable values were evaluated such that transfer efficiency η ≧ 99%, η ≧ 99% as ◯, 90% ≦ η <99% as Δ, and η <90% as ×.

  The above evaluation results are shown in Tables 2 and 3 below. The initial results are shown in Table 2, and the results after 20,000 sheets are shown in Table 3.

As is apparent from Table 2, the developers of Examples 1 to 5 had very good initial transferability and excellent developability.
On the other hand, as shown in the results of Comparative Examples 1 to 4, the developer containing toner to which melamine resin particles are externally added instead of the composite resin particles and the developer containing toner to which no composite resin particles are externally added are shown. There were variations in chargeability, and there were some problems in developability and transferability from the beginning.

As is apparent from Table 3, the developer containing the composite resin particles in the present invention as an external additive of the toner particles, as shown in the results of Examples 1 to 5, even when copying is continued for a long time. The change in charging characteristics was small between low temperature and low humidity and high temperature and high humidity, good developability and transferability, and good image quality even when used repeatedly for a long time.
Further, when the photoconductor was taken out after copying 20,000 sheets and the surface was observed, scratches and contamination were slight.
On the other hand, the developer containing toner to which PMMA particles, silica particles, etc. are added in place of the composite resin particles has poor transferability when copying is continued for a long time as shown in the results of Comparative Examples 1 to 4. Met. In Comparative Example 3, the occurrence of fog was particularly noticeable after long-time copying.

It is a schematic cross section which shows an example of the composite resin particle in this invention. It is a schematic explanatory drawing for demonstrating the method to measure the volume specific resistance value of a carrier.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Composite resin particle 2 Resin which comprises composite resin particle 3 Inorganic particle 12 Upper electrode 13 Measurement sample 14 Lower electrode 15 High voltage resistance meter

Claims (11)

  A two-component developer for developing an electrostatic latent image containing a toner and a carrier, wherein the toner contains toner particles containing at least a binder resin and a colorant and an external additive, and the external additive Contains a composite resin particle containing inorganic particles, a two-component developer for developing an electrostatic latent image.   The two-component developer for developing an electrostatic latent image according to claim 1, wherein the toner particles contain a release agent.   The two-component developer for developing an electrostatic latent image according to claim 1 or 2, wherein the composite resin particles have a volume average particle diameter of 0.05 to 2 µm. When the number average particle diameter of the composite resin particles is d ₅₀ , in the particle size distribution of the composite resin particles, the ratio of particles of 1/2 × d ₅₀ or less and the ratio of particles of 2 × d ₅₀ or more are respectively The two-component developer for developing an electrostatic latent image according to claim 1, wherein the two-component developer is 20% by number or less.   The two-component developer for electrostatic latent image development according to any one of claims 1 to 4, wherein the inorganic particles contained in the composite resin particles are partially exposed on the surface of the composite resin particles. .   The two-component developer for developing an electrostatic latent image according to claim 1, wherein the composite resin particles contain a resin containing a nitrogen atom.   The two-component developer for developing an electrostatic latent image according to claim 6, wherein the resin containing a nitrogen atom is a melamine resin.   The two-component developer for developing an electrostatic latent image according to any one of claims 1 to 7, wherein an average shape factor SF1 of the toner is in a range of 100 to 140.   The average shape factor SF1 of the toner is in the range of 125 to 140, the average shape factor SF2 is in the range of 105 to 130, and the volume average particle size of the composite resin particles is in the range of 80 to 300 nm. The two-component developer for developing an electrostatic latent image according to any one of claims 1 to 8.   10. The electrostatic latent image developing two-component according to claim 1, wherein the carrier has a resin coating layer in which a conductive material is dispersed and contained in a matrix resin on a core material surface. Developer. A charging unit that uniformly charges the electrostatic latent image carrier, a latent image forming unit that forms an electrostatic latent image by exposing the surface of the charged electrostatic latent image carrier, and the electrostatic latent image includes toner. An image forming apparatus including a developing unit that develops a toner image using a developer, a transfer unit that transfers the formed toner image to a recording material, and a fixing unit that fixes the transferred toner image on the surface of the recording material is used. An image forming method for forming an image
The developer is the developer according to any one of claims 1 to 10, and the transfer unit develops each color toner on a latent image carrier and transfers it to an intermediate transfer member, and then each color. An image forming method, which is a transfer unit that transfers toner to a recording material at a time.

Images