JP2005266564A - Electrostatic charge image developing developer and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic charge image developing developer capable of providing images of high image quality with high transfer efficiency over a prolonged period of time in a toner reclaiming system in which a recovered residual toner after transfer is returned to a development vessel and reused, and capable of preventing the occurrence of image defects such as image unevenness and fog while improving cleaning performance, and to provide an image forming method using the developer. <P>SOLUTION: In the electrostatic charge image developing developer with which an image is formed through a latent image forming step, a developing step, a transfer step and a cleaning step, and which is used in the toner reclaiming system, the toner comprises toner particles of a given shape and amorphous particles, a volume average particle diameter of the amorphous particles is within a range of 1-10 μm, and when a charge amount between the amorphous particles and carrier is represented by X and a charge amount between the toner and carrier by Y, the expression: 0.5≤X/Y≤1.4 is satisfied. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electrostatic charge image developing developer and an image forming method used in electrophotography, electrostatic recording method and the like.

  In electrophotography, an electrostatic latent image formed on the surface of a latent image carrier (photoconductor) is developed with a toner containing a colorant, and the obtained toner image is transferred to the surface of a recording material, which is then heated. An image is obtained by fixing with a roll or the like. On the other hand, the latent image carrier is cleaned with residual transfer toner to form an electrostatic latent image again. The dry developer used in such electrophotography is a one-component developer using a toner in which a colorant or the like is blended in a binder resin, and a two-component developer in which a carrier is mixed with the toner. Broadly divided. Furthermore, the one-component developer is conveyed by a developer carrier by magnetic force using magnetic powder, and is conveyed by the developer carrier by charging with a charging roll or the like without using magnetic powder and the magnetic one-component developer to be developed. And can be classified as a non-magnetic one-component developer to be developed.

  Since the latter half of the 1980's, there has been a strong demand for miniaturization and high functionality in the electrophotographic market with the key word being digitization, and high-quality quality close to high-quality printing and silver halide photography is desired for full color image quality. Similarly, for black and white image quality, high image quality is desired, and at the same time, high productivity, miniaturization, and low cost are required. As means for achieving high image quality, digitization processing is indispensable, and as an effect of digitization related to such image quality, it is mentioned 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. For image output, it is necessary to faithfully create an electrostatic latent image created by an optical system, and as a toner, the particle size is becoming increasingly smaller, and activities aimed at faithful reproduction are accelerated. On the other hand, it is also required to reduce the number of parts for miniaturization and extend the life of consumables for cost reduction, and the high performance and high reliability of the developer are propositions. Furthermore, in order to achieve high productivity, the speed of the latent image carrier has been increased, and in order to obtain a stable high image quality, the development, transfer, fixing, and cleaning processes have been greatly improved. Has become important. At the same time, it has become important to improve the functions such as the life extension function of other consumables using toner components.

  In particular, in the transfer process, it is necessary to faithfully transfer the developed toner image in order to improve the image quality. However, the transfer performance is deteriorated by reducing the diameter of the toner. For this reason, various techniques for using small-diameter toner have been reported. For example, it has been reported that the transfer performance is improved by bringing the toner closer to a spherical shape (see, for example, Patent Document 1). In this case, the transfer efficiency is improved by making the toner spherical, but on the other hand, a cleaning failure occurs due to a slight residual transfer toner.

  In contrast to the above, various means for cleaning the spherical toner have been proposed. For example, in the case of cleaning using a blade, it is important how to suppress the frictional force of the blade nip portion on the surface of the photosensitive member in a state where residual toner is interposed. (For example, refer to Patent Document 2). According to this method, the cleaning performance is improved initially, but the lubricant particles on the surface of the blade may be depleted during long-term use, resulting in poor cleaning. In addition, it has been proposed to apply a DC and AC bias voltage to the cleaning blade (see, for example, Patent Document 3). However, since the charge amount of the transfer residual toner varies depending on the charge amount of the developing toner, the transfer condition, the use environment, or the type of image, it cannot be completely cleaned by itself. Rather, the cleaning bias promotes the deterioration of the surface of the photoreceptor, and the life of the photoreceptor may be reduced.

  Further, although it has been proposed to increase the pressure contact force of the cleaning blade to the photosensitive member (see, for example, Patent Document 4), the initial cleaning performance is greatly improved, but the blade material or physical properties are taken into consideration. If not, the blade will be chipped and cleaning failure will occur. In addition, as long as an organic photoconductor is used as the photoconductor, the wear amount of the photoconductor increases and the photoconductor life may be reduced.

  Also, if the shape of the toner is made closer to a sphere in order to improve the transfer performance by reducing the diameter of the toner in order to improve the image quality as described above, cleaning becomes more difficult, so the linear pressure of the blade is increased. This makes it easier to remove the transfer residual toner on the photoconductor. However, this significantly increases the wear of the photoreceptor and blade.

  Accordingly, it is necessary to further improve the cleaning performance without deteriorating the charging performance and maintainability of the developer. In particular, in the case of color images, there is a method using an intermediate transfer member as a method for transferring an image. In this case, primary transfer from the latent image carrier to the intermediate transfer member, and from the intermediate transfer member to the recording medium. The secondary transfer and the second transfer are necessary, and at the same time, the cleaning performance of the toner remaining on the intermediate transfer member as well as the latent image carrier becomes important. In particular, since the intermediate transfer member needs to clean the residual toner for several colors, the requirement becomes severe. Further, a tandem system in which a latent image carrier and a developer carrier are placed according to each of the four colors, and an intermediate transfer member is directly transferred from the latent image carrier or a developer carrier, is advantageous in terms of total transfer efficiency and printing speed. It is. However, it needs to have a cleaning process with high speed suitability at the same time.

  Therefore, various studies have been made from the developer side. For example, it has been proposed to add a fatty acid metal salt to the toner (see, for example, Patent Document 5). This method is effective for reducing the frictional force at the nip portion between the cleaning blade and the photoconductor, but the amount of toner charge is greatly reduced by adding a fatty acid metal salt. Toner scattering tends to occur, and as a result, the image quality may deteriorate.

  In addition, a method of adding a polymer alcohol or a polymer fatty acid to the toner has been proposed. For example, a polymer alcohol having 30 to 300 carbon atoms is added to suppress toner spots (for example, patent documents). 6). In addition, it has been studied to suppress adhesion of toner and toner constituent materials to the photoreceptor by adding a polymer alcohol by various methods in blade cleaning (see, for example, Patent Documents 7 and 8). In these cases, it is described that a polymer alcohol or a polymer fatty acid forms a lubricating film on the surface of the photoreceptor during cleaning, and the film prevents toner and toner constituent materials from being filmed on the photoreceptor.

  However, this method requires a large amount of addition to form a sufficient lubricating film, and in this case, it has been shown that poor charging of the toner and a decrease in environmental stability newly occur (for example, patents). Reference 9). Therefore, in this method, it is proposed that the formation of a lubricating film on the photoreceptor is facilitated by adding a small amount by using in the range of 21 to 29 carbon atoms of the polymer alcohol or polymer fatty acid to be used. ing. However, in this method, the polymer alcohol and the fatty acid are easily softened, so that a lubricating film is easily formed, but at the same time, the carrier of the two-component developer, the developing sleeve of the one-component developer, the charging blade, etc. are contaminated. It becomes remarkable and the charge maintenance property of the developer is inferior.

  Therefore, a method for expressing the function of the cleaning aid more effectively with a small amount of addition has been proposed. For example, it has been proposed to positively supply the image background portion by regulating the charge amount of the amorphous particles as the cleaning aid to be added to a charge amount significantly lower than that of the toner (see, for example, Patent Document 10). ). In recent years, from the viewpoint of economy, resource saving, and environmental safety, a so-called toner reclaim method in which the toner collected in the cleaning process is returned to the developing device and reused as a developing toner has been attracting attention. For example, image quality improvement in reclaim has been proposed by defining the particle size and number ratio of external additives (see, for example, Patent Document 11).

However, in the above method, when the shape of the toner particles is made close to a sphere for improving the image quality, a sufficient cleaning assist function cannot be obtained and a cleaning failure occurs. In addition, it has been proposed to use a toner to which a fatty acid metal salt is externally added in a reclaim method (see, for example, Patent Document 12), but this method initially has both cleanability and developability. The fatty acid metal salt gradually desorbed from the toner with use over time is accumulated and concentrated in the developing device, and the chargeability of the developer is remarkably lowered and fogging occurs.
For this reason, there is a problem of achieving both cleaning suitability and long-term developability in the reclaim method using toner in which toner particles are made close to a sphere for high image quality.
Japanese Patent Laid-Open No. 62-184469 JP-A-4-212190 JP-A-5-265360 JP-A-4-001773 JP 2000-89502 A JP-A-63-188158 Japanese Patent Application Laid-Open No. 6-282096 Japanese Patent Laid-Open No. 9-6049 JP 2001-42562 A JP 2001-236384 A JP 2002-196526 A Japanese Patent Laid-Open No. 2002-14488

  An object of the present invention is to solve the conventional problems and to achieve the following problems. That is, an object of the present invention is to obtain a high-quality image with high transfer efficiency over a long period of time in a toner reclaim system in which the transfer residual toner collected in the cleaning process is returned to the developing device and the toner is reused. The present invention provides a developer for developing an electrostatic image capable of preventing image quality defects such as image unevenness and fog, and an image forming method using the same, while improving the cleaning property even when reused toner is included. Is.

  As a result of intensive studies to achieve the above object, the present inventors have developed a developer for developing an electrostatic latent image formed on the surface of a latent image carrier, and an image forming method using such a developer. As a result, the inventors have found that the above object can be achieved by using the following developer and image forming method, and have completed the present invention.

Specifically, means for solving the problems are as follows. That is,
<1> A step of forming a latent image on a latent image carrier, a development step of using the developer on the developer carrier as a toner image, a transfer step of transferring the toner image, and a latent image In the developer for developing an electrostatic charge image used in the toner reclaim method in which an image is formed by a cleaning process for removing toner remaining on the carrier, and the toner removed in the cleaning process is returned to the developing process.
The developer for developing an electrostatic charge image includes a toner and a carrier, and the toner includes toner particles having a shape factor SF1 of 120 or more and less than 140, and amorphous particles having a shape factor SF1 of 140 or more. When the volume average particle diameter of the regular particles is in the range of 1 to 10 μm, the charge amount between the amorphous particles and the carrier is X, and the charge amount between the toner and the carrier is Y, 0.5 ≦ A developer for developing an electrostatic charge image, wherein X / Y ≦ 1.4.

Here, the shape factor SF1 is an average value of the shape factors of the particles represented by the following formula (1).
SF1 = (ML ² / A) × (π / 4) × 100 (1)
In the above formula (1), ML represents the maximum length of each particle, and A represents the projected area of each particle.

<2> The developer for developing an electrostatic charge image according to <1>, wherein the amorphous particles are resin particles.

<3> The developer for developing an electrostatic charge image according to <1>, wherein the amorphous particles are polymer alcohol particles.

<4> The developer for developing an electrostatic charge image according to any one of <1> to <3>, wherein an addition amount of the amorphous particles is 0.5% by weight or more and 20% by weight or less. .

<5> The developer for developing an electrostatic charge image according to any one of <1> to <4>, wherein the surface of the amorphous particle has the same external additive as the surface of the toner particle.

<6> A step of forming a latent image on the latent image carrier, a development step of using the developer on the developer carrier as a toner image, a transfer step of transferring the toner image, and a latent image carrier In an image forming method comprising a cleaning step for removing toner remaining on the body, and a toner reclaim step for returning the toner removed in the cleaning step to a development step,
An image forming method, wherein the developer is the developer for developing an electrostatic image according to <1>.

The effects of the above means will be described as follows.
What is important as the toner characteristics necessary for the toner reclaim method is that there is a difference between the charge characteristics and the powder characteristics between the reclaim toner and the toner in the developing device. If the difference in charging characteristics is large, the charge amount distribution may expand due to the effects of mutual charging between the toner in the developing unit and the added reclaimed toner, causing toner scattering and fogging. When the toner is large, the mixing property of the developer and the reclaimed toner in the developing device is poor, and the reclaimed toner goes out of the developing device, resulting in toner scattering and fogging.

  In general, a toner having a large particle diameter is selectively developed and easily transferred. Further, in the transfer process, the toner is more easily transferred as it is closer to a sphere. Therefore, the reclaimed toner has a smaller particle size than the toner in the developing unit, and tends to increase in irregular shape. When this toner is added to the developing device, the amount of toner that is easily developed and transferred in the developer is reduced, so that the transferability is lowered due to a change with time. Therefore, the toner reclaim method requires a toner having high transfer efficiency.

  In order to achieve high transfer efficiency, it is effective that the toner has a shape factor SF1 of less than 140, but the toner has the following problems. That is, when cleaning is performed using a cleaning blade, toner remaining on the latent image carrier without being transferred (sometimes referred to as transfer residual toner) is dammed at the blade nip portion by the cleaning blade, and the residual toner A laminated part is formed. In the laminated portion, the residual toner is separated in particle size, and the particle size becomes finer as it approaches the blade. For this reason, the residual toner is easily arranged in the blade nip portion, so that the shape thereof is easily arranged, and the number of toner contact points per minute unit photoconductor surface in the blade nip portion is increased. Since the toner friction force is directed in the same direction, the total amount of force that the blade receives during cleaning is considerably large. As a result, the blade is pushed up, or the blade edge is chipped and the toner slips through the blade, resulting in poor cleaning.

  On the other hand, it is conceivable to increase the linear pressure of the cleaning blade, for example, so as not to cause toner cleaning failure. However, since the frictional force between the cleaning blade and the photosensitive member is further increased, the surface of the photosensitive member is also worn. In some cases, the life of the photosensitive member may be shortened.

  Therefore, in order to clean toner having a shape factor SF1 of less than 140, amorphous particles having a higher degree of irregularity than this toner, specifically, irregular particles having a shape factor SF1 of 140 or more are allowed to enter the cleaning blade together with the toner. As a result, it is possible to prevent the toner from being densely arranged and to suppress the cleaning blade push-up force. Since the irregularly shaped particles are not irregularly transferred and are likely to remain on the photoconductor without being transferred, the irregularly shaped particles can be arranged in the blade nip portion, and therefore, it is possible to prevent the passage of the blade due to the rolling of the toner, Even if the toner is used, the cleaning performance can be ensured, and as a result, it is possible to prevent image quality defects such as image unevenness and fog while improving the cleaning performance.

  Furthermore, the toner can be stably cleaned over a long period of time by reducing the frictional force between the toner and the photoreceptor at the cleaning blade nip. Usually, in order to supply a lubricant to the surface of the cleaning blade and form a lubricating surface on the surface of the photoreceptor, it is common to add the lubricant particles to the toner externally. In order to exert the effect of reducing the frictional force, it is necessary to considerably increase the amount of the lubricant particles added to the toner, and as a result, the chargeability of the toner may be greatly reduced.

  Therefore, if the effect of reducing the frictional force between the photosensitive member and the blade nip portion is given to specific irregular shaped particles, the toner can be stably cleaned for a longer period of time. The present inventors have found a developer that does not affect charging characteristics over a long period of time even in the reclaim system and does not cause defective cleaning by defining the relationship between the charge amount of the toner and the irregularly shaped particles.

  That is, the irregular shaped particles are collected together with the toner by the cleaning blade, returned to the developing device, and stirred together with the developer. At that time, the charge amount of the irregular particles contained in the toner in the developer and the carrier in the developer is lower than the charge amount of the toner and the carrier in the developer, that is, X / Y <0. In the case of 5, the charge amount of the developer is lowered, scattering in the machine, and fogging to the non-image area.

  In addition, the charge amount between the amorphous particles contained in the toner in the developer and the carrier in the developer is higher than the charge amount between the toner and the carrier in the developer, that is, X / Y> 1.4. In this case, the charge amount of the developer is raised, and as a result, the transfer efficiency is lowered.

  Preferably, it is preferable to align the surface externally added structure of the toner and the irregular shaped particles. Specifically, it is desirable to use the same external additive composition as that of the toner so as to have the same surface structure, that is, a mixture of amorphous particles externally added with the same external additive species. As a result, even if the irregularly shaped particles are a material having a low charge exchange capability such as a resin, it is possible to sufficiently exchange the charge with other external additives. Even if the particles are added, the charge distribution of the developer is not expanded, and good image quality can be stably obtained.

  At that time, it is preferable that the coating ratios of the external additives per surface area are substantially equal. With these configurations, it is possible to suppress an increase in charge distribution due to mutual charging of the toner in the developer and the reclaim toner, and it is possible to obtain a stable image quality due to a stable charge amount transition.

  Here, external addition of the same external additive species so that the coverage ratios of the external additives per surface area of the toner and the irregularly shaped particles are substantially equal is the value of C represented by the following formula (2). In each external additive, the toner and the irregularly shaped particles may be substantially aligned. That is, when the C value of the toner is 1, the C value of the amorphous particles is preferably 0.8 to 1.2, more preferably 0.9 to 1.1.

C = A × (2π / √3) × (da / dt) × (ρa / ρt) ÷ 100 (2)
The symbols in the above formula (2) are as follows.
C: Weight of external additive / particle weight A: Toner surface coverage of external additive [%]
da: Volume average particle diameter of external additive [μm]
dt: Volume average particle diameter of particles (D50) [μm]
ρa: True specific gravity of external additive ρt: True specific gravity of particles

  Furthermore, by reducing the frictional force between the toner and the photoreceptor at the blade nip portion, the toner having a shape factor SF1 of 120 to 140 can be efficiently cleaned. For this purpose, it is desirable to use particles having lubricity for the irregular shaped particles. The lubricant accumulates at the blade edge portion and acts as a cleaning aid, and at the same time forms a lubricating surface on the surface of the photoreceptor, and exhibits the effect of reducing the frictional force at the blade nip portion.

  Examples of the particles having lubricity include alcohols such as polymer alcohols, polyalkylenes such as polyethylene and polypropylene, higher fatty acids, esters of higher fatty acids and alcohols, higher fatty acid metal salts of higher fatty acids and metal salts. Preferably, polymer alcohols having 50 to 250 carbon atoms are preferred from the viewpoints of lubricity and cleaning properties.

  By the above, in the toner reclaim method in which the transfer residual toner collected in the cleaning process is returned to the developing unit and the toner is reused, image quality defects such as image unevenness are not caused while improving the cleaning property, It was possible to obtain an electrophotographic developer capable of improving the reliability by reducing the friction between the blade and the photoreceptor in a balanced manner.

  According to the present invention, it is possible to achieve a good improvement in reliability by reducing friction between the blade and the photosensitive member without causing image quality defects such as image unevenness while improving the cleaning property as described above. In particular, in the toner reclaim system in which the transfer residual toner collected in the cleaning process is returned to the developing unit and the toner is reused, in order to obtain the high-quality image, both the cleaning property and the long-term developing property are achieved. The purpose of preventing image quality defects such as image unevenness can be achieved in a balanced manner.

Hereinafter, the present invention will be described in detail.
<Developer for developing electrostatic image>
(toner)
The toner used in the present invention comprises toner particles and an external additive, and the external additive includes irregular particles having a volume average particle diameter of 1 to 10 μm and a shape factor SF1 of 140 or more.

-Toner particles-
Specific examples of the toner particle production method include, for example, a kneading and pulverizing method in which a binder resin, a colorant, and, if necessary, a release agent, a charge control agent, and the like are kneaded, pulverized, and classified; A method of changing the shape of the obtained particles by mechanical impact force or thermal energy; emulsion polymerization of a polymerizable monomer constituting a binder resin, a binder resin particle dispersion formed, a colorant, And emulsion polymerization aggregation method to obtain toner particles by mixing with each material dispersion liquid in which a release agent, charge control agent, etc. are dispersed in a liquid, if necessary, to obtain toner particles; constituting a binder resin A suspension polymerization method in which a colorant and, if necessary, a release agent, a charge control agent, and the like are dissolved and dispersed in a polymerizable monomer to be polymerized and suspended in an aqueous medium; And granulate by suspending the colorant and, if necessary, a release agent, charge control agent, etc. in an aqueous solvent Dissolution suspension method; and the like can be used.
Among these, the shape controllability, the particle size, and the controllability of the particle size distribution, especially the emulsion polymerization aggregation method capable of controlling the generation of coarse and fine powders are optimal because there is no shear during granulation.

Hereinafter, the emulsion polymerization aggregation method will be described.
In the emulsion polymerization aggregation method, a resin particle dispersion in which resin particles having a particle diameter of 1 μm or less are dispersed, a colorant dispersion in which a colorant is dispersed, and the like are mixed to aggregate the resin particles and the colorant into a toner particle diameter. (Hereinafter, sometimes referred to as “aggregation step”), a step of heating the resin particles to a temperature equal to or higher than the glass transition point of the resin particles to fuse the aggregates to form toner particles (hereinafter, sometimes referred to as “fusion step”). including.

  In the aggregation step, the resin particle dispersion, the colorant dispersion, and, if necessary, the particles in the release agent dispersion are aggregated to form aggregated particles. The agglomerated particles are formed by heteroaggregation or the like. For the purpose of stabilizing the agglomerated particles and controlling the particle size / particle size distribution, the ionic surfactant having a polarity different from that of the agglomerated particles, or a monovalent or more monovalent metal salt or the like is used. A charged compound is added.

  In the fusion step, the resin particles in the aggregated particles are melted at a temperature condition equal to or higher than the glass transition point, and the aggregated particles change from an indeterminate shape to a spherical shape. At this time, the shape factor SF1 of the aggregated particles is 140 or more. However, the shape factor SF1 is controlled to be 120 or more and less than 140 by stopping the heating of the toner when the desired shape factor is reached. be able to. Thereafter, the agglomerates are separated from the aqueous medium, and washed and dried as necessary to form toner particles.

Specific examples of preferable binder resins used in the present application include known resin materials. For example, styrenes such as styrene, parachlorostyrene, α-methylstyrene: methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate , Esters having vinyl groups such as ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, etc .: vinyl nitriles such as acrylonitrile and methacrylonitrile: vinyl ethers such as vinyl methyl ether and vinyl isobutyl ether Class: Vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl ketone, etc .: Polyolefins such as ethylene, propylene, butadiene, etc .: Homopolymers of monomers such as two or more of these Copolymers obtained by combining them or mixtures thereof can be mentioned, and further, epoxy resins, polyester resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, etc., non-vinyl condensation resins, or these and the vinyl Examples thereof include a mixture with a resin and a graft polymer obtained when a vinyl monomer is polymerized in the presence of these.
Among these, styrene-alkyl acrylate copolymers and styrene-alkyl methacrylate copolymers are particularly preferable.

  In the toner of the present invention, in order to improve the chargeability with the carrier, a dissociative vinyl monomer may be contained together with the monomer constituting the binder resin during the polymerization of the binder resin. The dissociative vinyl monomer is a raw material for polymer acids and polymer bases such as acrylic acid, methacrylic acid, maleic acid, cinnamic acid, fumaric acid, vinylsulfonic acid, ethyleneimine, vinylpyridine, and vinylamine. Any monomer can be used. Polymer acids are preferred because of the ease of polymer formation reaction, among others, dissociable vinyl monomers having a carboxyl group such as acrylic acid, methacrylic acid, maleic acid, cinnamic acid, fumaric acid, etc. It is preferable from the viewpoint of controllability. In addition, these dissociative vinyl monomers can be used by copolymerizing usually at the time of binder resin polymerization.

  In the toner of the present invention, a chain transfer agent can be used during the polymerization of the binder resin. Although there is no restriction | limiting in particular as a chain transfer agent, The compound which has a thiol component can be used. Specifically, alkyl mercaptans such as hexyl mercaptan, heptyl mercaptan, octyl mercaptan, nonyl mercaptan, decyl mercaptan, and dodecyl mercaptan are preferred, and in particular, the molecular weight distribution is narrow, so that the storage stability of the toner at high temperature is improved. preferable.

A cross-linking agent may be added to the binder resin in the present invention as necessary.
Specific examples of such crosslinking agents include aromatic polyvinyl compounds such as divinylbenzene and divinylnaphthalene; divinyl phthalate, divinyl isophthalate, divinyl terephthalate, divinyl homophthalate, divinyl trimesate / trivinyl, naphthalene dicarboxylate Polyvinyl esters of aromatic polyvalent carboxylic acids such as divinyl acid and diphenyl biphenyl carboxylate; Divinyl esters of nitrogen-containing aromatic compounds such as divinyl pyridine dicarboxylate; Vinyl pyromutate, vinyl furan carboxylate, pyrrole-2- Vinyl esters of unsaturated heterocyclic compounds such as vinyl carboxylate and vinyl thiophenecarboxylate; butanediol methacrylate, hexanediol acrylate, octanediol methacrylate, decanediol acrylate (Meth) acrylic acid esters of linear polyhydric alcohols such as dodecanediol methacrylate; branches such as neopentylglycol dimethacrylate and 2-hydroxy-1,3-diacryloxypropane; ) Acrylic acid esters; Polyethylene glycol di (meth) acrylate, Polypropylene polyethylene glycol di (meth) acrylates; Divinyl succinate, divinyl fumarate, vinyl / divinyl maleate, divinyl diglycolate, vinyl / divinyl itaconate, acetone Divinyl dicarboxylate, divinyl glutarate, divinyl 3,3′-thiodipropionate, trans-aconite divinyl / trivinyl, divinyl adipate, divinyl pimelate, divinyl suberate, dibi azelate Le, sebacate, divinyl dodecanedioate divinyl, the polyvinyl esters of polycarboxylic acids such as oxalic acid, divinyl; and the like.

In the present invention, these crosslinking agents may be used alone or in combination of two or more. Among the above crosslinking agents, as the crosslinking agent in the present invention, (meth) acrylic acid esters of linear polyhydric alcohols such as butanediol methacrylate, hexanediol acrylate, octanediol methacrylate, decanediol acrylate, and dodecanediol methacrylate are used. Branched chains such as neopentyl glycol dimethacrylate and 2-hydroxy-1,3-diacryloxypropane, (meth) acrylic acid esters of substituted polyhydric alcohols; polyethylene glycol di (meth) acrylate, polypropylene polyethylene glycol di ( It is preferable to use (meth) acrylates.
The content of the crosslinking agent is preferably in the range of 0.05 to 5% by weight, more preferably in the range of 0.1 to 1.0% by weight, based on the total amount of polymerizable monomers.

The resin used for the toner in the present invention can be produced by radical polymerization of a polymerizable monomer.
There is no restriction | limiting in particular as an initiator for radical polymerization used here. Specifically, hydrogen peroxide, acetyl peroxide, cumyl peroxide, tert-butyl peroxide, propionyl peroxide, benzoyl peroxide, chlorobenzoyl peroxide, dichlorobenzoyl peroxide, bromomethylbenzoyl peroxide, lauroyl peroxide Ammonium persulfate, sodium persulfate, potassium persulfate, diisopropyl peroxycarbonate, tetralin hydroperoxide, 1-phenyl-2-methylpropyl-1-hydroperoxide, tert-butyl hydroperoxide pertriphenyl acetate, tert-butyl formate, Peroxides such as tert-butyl peracetate, tert-butyl perbenzoate, tert-butyl perphenylacetate, tert-butyl permethoxyacetate, tert-butyl perN- (3-toluyl) carbamate, 2,2 '-Azobispro Bread, 2,2′-dichloro-2,2′-azobispropane, 1,1′-azo (methylethyl) diacetate, 2,2′-azobis (2-amidinopropane) hydrochloride, 2,2 ′ -Azobis (2-amidinopropane) nitrate, 2,2'-azobisisobutane, 2,2'-azobisisobutyramide, 2,2'-azobisisobutyronitrile, 2,2'-azobis-2- Methyl methylpropionate, 2,2′-dichloro-2,2′-azobisbutane, 2,2′-azobis-2-methylbutyronitrile, dimethyl 2,2′-azobisisobutyrate, 1,1′-azobis (1 -Methylbutyronitrile-3-sodium sulfonate), 2- (4-methylphenylazo) -2-methylmalonodinitrile, 4,4'-azobis-4-cyanovaleric acid, 3,5-dihydroxymethylphenyl Zo-2-methylmalonodinitrile, 2- (4-bromophenylazo) -2-allylmalonodinitrile, 2,2'-azobis-2-methylvaleronitrile, 4,4'-azobis-4-cyanoyoshi Dimethyl herbate, 2,2′-azobis-2,4-dimethylvaleronitrile, 1,1′-azobiscyclohexanenitrile, 2,2′-azobis-2-propylbutyronitrile, 1,1′-azobis-1 -Chlorophenylethane, 1,1'-azobis-1-cyclohexanecarbonitrile, 1,1'-azobis-1-cycloheptanenitrile, 1,1'-azobis-1-phenylethane, 1,1'-azobiscumene, 4-Nitrophenylazobenzylcyanoacetate, phenylazodiphenylmethane, phenylazotriphenylmethane, 4-nitrophenylazotrif Nylmethane, 1,1′-azobis-1,2-diphenylethane, poly (bisphenol A-4,4′-azobis-4-cyanopentanoate), poly (tetraethylene glycol-2,2′-azobisiso) Azo compounds such as butyrate), 1,4-bis (pentaethylene) -2-tetrazene, 1,4-dimethoxycarbonyl-1,4-diphenyl-2-tetrazene and the like.

  The toner particle colorants include magnetic powders such as magnetite and ferrite, carbon black, aniline blue, calcoil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, and malachite green. Oxalate, 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 180, 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.

  In addition, a release agent or a charge control agent may be added to the toner particles used in the present invention as necessary. Typical examples of the release agent include low molecular polyethylene, low molecular polypropylene, Fischer-Tropsch wax, montan wax, carnauba wax, rice wax, and candelilla wax.

  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. The toner in the present invention may be either a magnetic toner containing a magnetic material or a non-magnetic toner containing no magnetic material.

  Here, in the aggregation step of the emulsion polymerization aggregation method, an inorganic metal salt having a charge of 2 or more can be used as an aggregating agent. Specifically, magnesium chloride, aluminum sulfate, calcium sulfate, aluminum nitrate, sulfuric acid can be used. Examples thereof include copper and polyaluminum chloride.

  The toner particles produced as described above preferably have a volume average particle diameter in the range of 2 to 12 μm, and more preferably in the range of 3 to 9 μm.

As described above, the toner particles used in the present invention must have a shape factor SF1 of 120 or more and less than 140 from the viewpoints of improving developability and transfer efficiency and improving image quality. The degree of spheroidization of the toner particles can be expressed using a shape factor ML ² / A of the following formula (1). The average value of the following coefficient coefficient SF1 of the toner particles used in the present invention is more preferably in the range of 125 or more and less than 140.

SF1 = (ML ² / A) × (π / 4) × 100 (1)
In the above formula (1), ML represents the maximum length of each particle, and A represents the projected area of each particle.

When the average value of the shape factor SF1 is 140 or more, the transfer efficiency is lowered, and the image quality of the print sample is lowered. If it is less than 120, cleaning becomes difficult, and the life of the cleaning blade may be shortened.
The average value of the shape factor SF1 is obtained by taking 1000 toner images magnified 250 times from an optical microscope into an image analyzer (LUZEX III, manufactured by Nireco), and determining the individual particle size based on the maximum length and projected area. Is obtained by averaging the values of SF1.

  The toner particles used in the present invention are not particularly limited by the production method as long as they satisfy the above-described shape factor SF1 and particle size, and a known method can be used.

  The amorphous particles added to the toner have a volume average particle size in the range of 1 to 10 μm, a shape factor SF1 of 140 or more, and a charge amount in the range of 0.5 to 1.4 with respect to the toner. Other than that, there is no particular limitation, and resin particles, lubricant particles, abrasive particles, and the like are used.

  Examples of resin particles include styrenes such as styrene and chlorostyrene; monoolefins such as ethylene, propylene, butylene, and isoprene; vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate, and vinyl butyrate; acrylic acid Α-methylene aliphatic monocarboxylic acid esters such as methyl, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate; Homopolymers and copolymers of vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl butyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, vinyl isopropenyl ketone; Typical resins include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer. Examples thereof include coalescence, polyethylene, and polypropylene. Further examples include polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin wax and the like. Those obtained by pulverization or the like can be used.

  As the abrasive particles, inorganic oxide particles are mainly used. As the material type, known inorganic oxide materials can be used. For example, cerium oxide, strontium titanate, magnesium oxide, alumina, silicon carbide, zinc oxide, silica, titanium oxide, boron nitride, calcium pyrophosphate, zirconia Examples thereof include abrasive particles such as barium titanate, calcium titanate, and calcium carbonate. Moreover, you may use these composite materials.

In addition, as lubricant particles, solid lubricants such as graphite, molybdenum disulfide, talc, fatty acids, aliphatic alcohols, polymer alcohols, fatty acid metal salts, and spherical silica, and low molecular weight polyolefins such as polypropylene, polyethylene, and polybutene; heating Silicones with softening points due to; aliphatic amides such as oleic amide, erucic acid amide, ricinoleic acid amide, stearic acid amide; carnauba wax, rice wax, candelilla wax, wood wax, jojoba oil, etc. Plant waxes; animal waxes such as beeswax; minerals such as montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, Fischer-Tropsch wax, and petroleum waxes; and their modified products There.
Among these, lubricant particles, particularly preferably polymer alcohol particles, are preferably used for forming a lubricating surface on the surface of the photoreceptor for improving the cleaning property.

The carbon number of the polymer alcohol is not particularly limited, but a polymer aliphatic alcohol having 16 to 150 carbon atoms and the like is preferably used. More preferably, it is 20-120, More preferably, it is the range of 30-100.
These particles may be added alone or in combination of two or more. The amount added is not particularly limited, but is preferably 0.1 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, and still more preferably 0.5 to 2 parts per 100 parts by weight of the toner particles. Parts by weight.

(Calculation method of charge amount ratio)
The charge amount ratio X / Y between the toner and the amorphous particles can be calculated by measuring the charge amount of the amorphous particles and the carrier and the charge amount of the toner and the carrier before mixing the amorphous particles. In addition, the charge spectrograph method described later is used to mix toner and amorphous particles, and after mixing the carrier with this, the charge amount between the toner and carrier and between the amorphous particle and carrier is measured by image analysis, Can be calculated.

  The former charge amount measurement method is not particularly defined, but representative examples include a blow-off charge amount measurement device represented by Toshiba's TB200, “E-Spart Analyzer” manufactured by Hosokawa Micron, For example, a spectrograph method.

  The latter measurement can be performed as follows. For example, as a method of discriminating the charging peak of the whole toner and each of the irregular shaped particles, the toner trajectory measured by the charge spectrograph method is further subjected to image analysis to obtain a Q / M distribution, and at the same time, the shape evaluation for each particle is also performed. Thus, the peak value Q / M (TN) of the entire toner and the peak value Q / M (PA) derived from the amorphous particles can be obtained.

The toner in the present invention includes irregularly shaped particles, but other particles can also be used. For example, it is preferable to include a small-diameter inorganic oxide having a primary particle size of 7 to 40 nm in terms of volume average particle size, which has functions such as powder flowability and charge control. Examples of the small-diameter inorganic oxide include silica, alumina, titanium oxide (such as titanium oxide and metatitanium oxide), calcium carbonate, magnesium carbonate, calcium phosphate, and carbon black.
In particular, it is preferable to use titanium oxide having a volume average particle size of 15 to 40 nm in that good chargeability, environmental stability, fluidity, and stable chargeability can be obtained without affecting the transparency.

  In addition, the surface treatment of the small-diameter inorganic fine particles increases the dispersibility and increases the powder flowability. Specifically, a hydrophobic treatment with a silane coupling agent such as dimethyldimethoxysilane, hexamethyldisilazane (HMDS), methyltrimethoxysilane, isobutyltrimethoxysilane, decyltrimethoxysilane or the like is preferably used as the surface treatment.

  Further, in addition to the small-diameter inorganic oxide and the irregularly shaped particles, it is preferable to add a large-diameter inorganic oxide having a volume average particle size of 20 to 300 nm in order to reduce adhesion and control charging. These large-diameter inorganic oxide fine particles include silica, titanium oxide, metatitanate compound, aluminum oxide, magnesium oxide, alumina, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, chromium oxide, Fine particles such as antimony trioxide, magnesium oxide, zirconium oxide and the like can be mentioned. Among these, it is desirable to use one selected from silica, titanium oxide, and metatitanic acid compound from the viewpoint of precise charge control of the toner added with lubricant particles and cerium oxide.

  In particular, in an image that requires high transfer efficiency such as a full-color image, the silica has a monodisperse spherical shape having a true specific gravity of 1.3 to 1.9 and a volume average particle size of 80 to 300 nm. Silica is preferred. By controlling the true specific gravity to 1.9 or less, peeling from the toner particles can be suppressed. Further, by controlling the true specific gravity to 1.3 or more, aggregation and dispersion can be suppressed. The true specific gravity of the monodispersed spherical silica is more preferably in the range of 1.4 to 1.8.

  If the volume average particle size of the monodispersed spherical silica is less than 80 nm, it may not be effective in reducing non-electrostatic adhesion between the toner and the photoreceptor. In particular, monodispersed spherical silica is easily embedded in toner particles due to stress in the developing device, and the effect of improving developability and transferability is likely to be significantly reduced. On the other hand, if it exceeds 300 nm, it will be easy to detach from the toner particles, and it will not work effectively to reduce the non-electrostatic adhesion force, and at the same time, it will easily move to the contact member, causing secondary obstacles such as charging inhibition and image quality defects. It becomes easy to cause. The volume average particle diameter of the monodispersed spherical silica is more preferably 100 to 200 nm.

  Since the monodispersed spherical silica is monodispersed and spherical, the monodispersed spherical silica is uniformly dispersed on the surface of the toner particles, and a stable spacer effect can be obtained. The above-mentioned monodispersion can be discussed with a standard deviation with respect to the volume average particle diameter including aggregates, and the standard deviation means a volume average particle diameter D50 × 0.22 or less. The spherical shape can be discussed by Wadell's degree of sphericity. The degree of sphericity is 0.6 or more, and more preferably 0.8 or more.

The degree of spheroidization was obtained from the following equation for the degree of spheroidization of Wadell.
Degree of sphericity = (surface area of sphere having the same volume as actual particle) / (surface area of actual particle)
In the above formula, the molecule (surface area of a sphere having the same volume as the actual particle) was calculated from the volume average particle diameter. The denominator (actual particle surface area) was substituted from the BET specific surface area using Shimadzu powder specific surface area measuring device SS-100.

  The reason why silica is preferable is that the refractive index is around 1.5, and even if the particle size is increased, the transparency decreases due to light scattering, especially the PE value (light transmission index) at the time of taking an image on the OHP surface, etc. It does not affect

  The addition amount of the small-diameter inorganic oxide is preferably in the range of 0.5 to 2.0 parts by weight with respect to 100 parts by weight of the toner particles. When the large-diameter inorganic oxide is added to the particles other than the amorphous particles, the large-diameter inorganic oxide is added in an amount of 1.0 to 5.0 parts by weight with respect to 100 parts by weight of the toner particles. It is preferable.

  Since the toner particle used in the present invention has a shape factor SF1 of 120 or more and less than 140, the effect of adding the inorganic oxide is also superior to that of an amorphous toner particle. That is, when the same amount of inorganic oxide is added to the toner particles, the powder flowability of the toner particles having a shape factor SF1 of 120 or more and less than 140 is considerably higher than in the case of the irregular toner particles. As a result, even if the toner charge amount is approximately the same, the toner exhibits high developability and transferability.

  The toner used in the present invention can be produced by mixing the external additive containing the toner particles and irregular particles with a Henschel mixer or a V blender. In addition, when the toner particles are produced by a wet method, external addition can be performed by a wet method. Further, the toner is obtained by further mixing an amorphous particle external additive in which amorphous particles and other external additives are mixed, and a toner particle external additive in which external additives other than irregular particles are mixed. You can also

(Career)
The carrier that can be used in the developer for developing an electrostatic charge image of the present invention is not particularly limited, but charge exchange with a reclaimed toner having a volume resistivity of 1 × 10 ¹² to 1 × 10 ¹⁶ Ω · cm is possible. It can be preferably used from the viewpoint of stabilization of the charge amount distribution due to the property. More preferably, it is 5 × 10 ¹³ to 1 × 10 ¹⁶ Ω · cm. When the volume resistivity is less than 1 × 10 ¹² Ω · cm, the carrier may adhere to the surface of the photoreceptor. When the volume resistivity exceeds 10 ¹⁶ Ω · cm, the charge exchange property is low and the chargeability of the reclaim toner is low. May not be stable and may cause toner scattering and fogging.

  Moreover, there is no restriction | limiting in particular as a manufacturing method of a carrier, For example, the resin coat carrier which has a resin coating layer on the core material surface can be mentioned. Further, a resin-dispersed carrier in which magnetic powder or the like is dispersed in a matrix resin may be used.

  Coating resins and matrix resins used for carriers include polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, styrene-acrylic. Examples include acid copolymers, straight silicone resins composed of organosiloxane bonds or modified products thereof, fluororesins, polyesters, polycarbonates, phenol resins, epoxy resins, urea resins, urethane resins, melamine resins, etc. It is not limited.

  In general, the carrier preferably has an appropriate electric resistance value, and it is preferable to disperse the conductive fine powder in the resin for adjusting the resistance. Examples of the conductive fine powder include metals such as gold, silver and copper, carbon black, titanium oxide, zinc oxide, barium sulfate, aluminum borate, potassium titanate, tin oxide, and carbon black. However, it is not limited to these.

  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 use the carrier for the magnetic brush method, a magnetic material is used. Preferably there is. The volume average particle size of the carrier core material is preferably in the range of 10 to 100 μm, and more preferably in the range of 25 to 50 μm.

  In order to coat the surface of the core material of the carrier with a resin, a method of coating the coating resin and, if necessary, various additives with a solution for forming a coating layer dissolved in an appropriate solvent is employed. The solvent is not particularly limited and may be appropriately selected in consideration of the coating resin to be used, coating suitability, and the like.

  Specific resin coating methods include a dipping method in which the powder of the carrier core material is immersed in the coating layer forming solution, a spray method in which the coating layer forming solution is sprayed on the surface of the carrier core material, and a carrier core material. Examples thereof include a fluidized bed method in which a coating layer forming solution is sprayed in a state of being suspended by flowing air, and a kneader coater method in which a carrier core material and a coating layer forming solution are mixed in a kneader coater to remove the solvent.

(Developer for developing electrostatic image)
The developer for developing an electrostatic image of the present invention is produced by mixing the toner and the carrier described above. The mixing ratio (weight ratio) of the toner and the carrier in the developer is preferably in the range of toner: carrier = 1: 99 to 20:80, preferably in the range of 3:97 to 12:88. It is more preferable.

<Image forming method>
The image forming method of the present invention will be described in detail below.
The image forming method of the present invention is formed on the surface of the latent image carrier using a latent image forming step for forming an electrostatic latent image on the surface of the latent image carrier and a developer carried on the developer carrier. A developing process for developing a latent image by forming an electrostatic latent image, a transfer process for transferring the toner image formed on the surface of the latent image carrier to the surface of the recording medium or intermediate transfer body, and the surface of the recording medium A fixing process for thermally fixing the toner image transferred to the surface, a cleaning process for cleaning the toner remaining on the surface of the latent image carrier, and a reclaiming process for returning the transfer residual toner collected in the cleaning process to the developing device. The developer for developing an electrostatic charge image according to the present invention is used as the developer.

  The latent image forming step is a step of forming an electrostatic latent image by uniformly charging the surface of the latent image carrier with a charging means and then exposing the latent image carrier with a laser optical system or an LED array. It is. Examples of the charging means include a non-contact charger such as corotron and scorotron, and a contact method in which a latent image carrier surface is charged by applying a voltage to a conductive member in contact with the latent image carrier surface. Any type of charger may be used. However, a contact charging type charger is preferable from the viewpoint that the amount of ozone generated is small, environmentally friendly, and excellent printing durability. In the contact charging type charger, the shape of the conductive member may be any of a brush shape, a blade shape, a pin electrode shape, a roller shape, and the like, but a roller-like member is preferable. The image forming method of the present invention is not subject to any particular limitation in the latent image forming process.

  The developing step is a step of bringing a developer carrying member having a developer layer containing at least toner on the surface thereof into contact with or approaching the surface of the latent image carrying member to the electrostatic latent image on the surface of the latent image carrying member. In which a toner image is formed on the surface of the latent image carrier. The development method can be performed using a known method, and examples of the development method using the two-component developer used in the present invention include a cascade method and a magnetic brush method. The image forming method of the present invention is not particularly limited with respect to the developing method.

  The transfer step is a step of directly transferring the toner image formed on the surface of the latent image carrier to the recording medium or transferring the image once transferred to the intermediate transfer body to the recording medium to form a transfer image. It is.

  A corotron can be used as a transfer device for transferring the toner image from the latent image carrier to paper or the like. The corotron is effective as a means for uniformly charging the paper, but a high voltage of several kV must be applied and a high voltage power source is required in order to give a predetermined charge to the paper as a recording medium. Further, since ozone is generated by corona discharge, the rubber parts and the latent image carrier are deteriorated. Therefore, a conductive transfer roll made of an elastic material is pressed against the latent image carrier to transfer the toner image onto the paper. A contact transfer method is preferred. In the image forming method of the present invention, the transfer device is not particularly limited.

  The cleaning step is a step of removing toner, paper dust, dust and the like adhering to the surface of the latent image carrier by bringing a blade, a brush, a roll or the like into direct contact with the surface of the latent image carrier. The most commonly employed method is a blade cleaning method in which a rubber blade such as polyurethane is pressed against the latent image carrier. On the other hand, a magnet is fixedly arranged inside, a rotatable cylindrical non-magnetic sleeve is provided on the outer periphery thereof, and a magnetic carrier system that collects toner by carrying a magnetic carrier on the sleeve surface, or a semiconductive It is also possible to remove the toner by making the resin fiber or animal hair rotatable in the form of a roll and applying a bias having a polarity opposite to that of the toner to the roll. In the former magnetic brush system, a cleaning pretreatment corotron may be provided. In the image forming method of the present invention, the cleaning method is preferably a cleaning step having at least a blade.

  The reclaim process is not particularly limited as long as it is a process of adding the toner collected in the cleaning process into the developing device. For example, the toner collected in the cleaning step is a step of feeding the developer into the developing device using a conveyor, a conveyance screw, pneumatic transportation, free fall, and the like. Also, the charging method into the developing device is not particularly limited. For example, it may be added directly into the developing device, or may be added to the replenishing toner hopper or cartridge and added to the developing device together with the toner. Alternatively, the toner may be supplied to the developing device after being mixed with the replenishing toner in the intermediate chamber.

  The fixing step is a step of fixing the toner image transferred to the surface of the recording medium with a fixing device. As the fixing device, a heat fixing device using a heat roll is preferably used. The heat fixing device includes a fixing roller having a heater lamp for heating inside a cylindrical metal core, a so-called release layer formed on the outer peripheral surface by a heat resistant resin film layer or a heat resistant rubber film layer, and the fixing roller. The pressure roller or pressure belt is disposed in pressure contact with the roller and has a heat-resistant elastic layer formed on the outer peripheral surface of the cylindrical metal core or the surface of the belt-like base material. The fixing process of the unfixed toner image is performed by inserting a recording material on which an unfixed toner image is formed between a fixing roller and a pressure roller or a pressure belt, and using a binder resin, an additive, and the like in the toner. Fix by heat melting. In the image forming method of the present invention, the fixing method is not particularly limited.

  In the image forming method of the present invention, when producing a full-color image, each of the plurality of latent image carriers has a developer carrier of each color, and the plurality of latent image carriers and developer carriers. Each color toner image is sequentially laminated on the same surface of the recording medium by a series of processes including a latent image forming process, a developing process, a transferring process, and a cleaning process, and the stacked full-color toners. An image forming method in which an image is thermally fixed in a fixing step is preferably used. By using the developer for electrophotography in the image forming method, stable development, transfer, and fixing performance can be obtained even in a tandem system suitable for, for example, small size and high-speed color.

  Examples of the recording material to which the toner image is transferred include plain paper, OHP sheet, and the like used in electrophotographic copying machines and printers. In order to further improve the smoothness of the image surface after fixing, it is preferable that the surface of the transfer object is as smooth as possible. For example, coated paper in which the surface of plain paper is coated with a resin or the like, art paper for printing Etc. can be used suitably.

  According to the image forming method using the developer for developing an electrostatic charge image of the present invention, the transfer residual toner collected in the cleaning process is returned to the developing device, and the toner reclaiming method in which the toner is reused has high transfer efficiency. A high-quality image can be obtained, and while improving cleaning properties, image quality defects such as image unevenness and fog are not caused at the same time, and reliability by reducing friction between the blade and the photoconductor can be improved.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In the following description, “parts” means “parts by weight” unless otherwise specified.

<Method for measuring physical properties>-
(Particle size distribution of toner particles, irregular particles, irregular particles)
The particle size and particle size distribution measurement in the present invention will be described. When the particle | grains to measure in this invention are 2 micrometers or more, Coulter counter TA-II type (made by Beckman-Coulter company) was used as a measuring apparatus, and ISOTON-II (made by Beckman-Coulter company) was used for electrolyte solution.

  As a measuring method, 0.5 to 50 mg of a measurement sample is added to 2 ml of a 5% aqueous solution of a surfactant, preferably sodium alkylbenzenesulfonate as a dispersant. This was added to 100 to 150 ml of the electrolytic solution. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 minute, and the particle size distribution of particles of 2 to 60 μm is measured using the Coulter counter TA-II with an aperture diameter of 100 μm. Volume average distribution and number average distribution were determined. The number of particles to be measured was 50,000.

  Moreover, when the particle diameter of the particle | grains measured in this invention is less than 2 micrometers, it measured using the laser diffraction type particle size distribution measuring apparatus (LA-700: product made from Horiba). As a measuring method, a sample in a dispersion is prepared so as to have a solid content of about 2 g, and ion exchange water is added thereto to make about 40 ml. This is put into the cell until an appropriate concentration is reached, waits for about 2 minutes, and is measured when the concentration in the cell becomes almost stable. The obtained particle diameter for each channel was accumulated from the smaller particle diameter, and the volume average particle diameter (sometimes referred to as D50) was determined to be 50%.

(Measurement method of molecular weight and molecular weight distribution of toner and resin particles)
In the developer for developing an electrostatic image of the present invention, the specific molecular weight distribution is obtained under the following conditions. GPC uses “HLC-8120GPC, SC-8020 (manufactured by Tosoh Corporation)”, and the column uses two “TSKgel, SuperHM-H (6.0 mm ID × 15 cm, manufactured by Tosoh Corporation)” THF (tetrahydrofuran) was used as an eluent. As experimental conditions, the sample concentration was 0.5%, and the flow rate was 0.6 ml / min. The experiment was conducted using a sample injection amount of 10 μl, a measurement temperature of 40 ° C., and an IR detector. The calibration curve is “polystylen standard sample TSK standard” manufactured by Tosoh Corporation: “A-500”, “F-1”, “F-10”, “F-80”, “F-380”, “A-2500”. ”,“ F-4 ”,“ F-40 ”,“ F-128 ”, and“ F-700 ”.

(Measuring method of melting point of release agent and glass transition temperature of toner)
The melting point of the release agent used for the toner in the present invention and the glass transition temperature of the toner were determined from the main maximum peak measured according to ASTM D3418-8.
DSC-7 manufactured by Perkin Elmer Co. can be used for measurement of the main maximum peak. The temperature correction of the detection part of this apparatus uses the melting point of indium and zinc, and the correction of heat quantity uses the heat of fusion of indium. As the sample, an aluminum pan was used, an empty pan was set as a control, and the measurement was performed at a heating rate of 10 ° C./min.

(Calculation of charge amount of toner and amorphous particles)
The developer is measured by a charge spectrograph, and first, the charge amount Q / M (TN) of the whole toner is calculated from the locus of the toner. Thereafter, the toner particles externally added with pigments and non-white irregular particles are separated by image analysis, and the charge amount Q / M (PA) of the irregular particles is determined only from those derived from the irregular particles. calculate.

(Image density)
Measurement was performed using an image densitometer (X-Rite 404A: manufactured by X-Rite).

(Carrier volume resistivity)
A sample of the carrier was filled on the lower electrode of the cell (100 mmφ, thickness 1.0 mm), the upper electrode was set, a load of 3.43 kg was applied from above, and the thickness was measured with a dial gauge. Next, voltage was applied and the current value was read to determine the volume resistivity.

<Manufacture of toner particles>
(Preparation of resin fine particle dispersion)
A solution obtained by mixing 370 parts of styrene, 30 parts of n-butyl acrylate, 8 parts of acrylic acid and 24 parts of dodecanethiol and dissolving 6 parts of a nonionic surfactant (Nonipol 400: manufactured by Sanyo Chemical Co., Ltd.) and anionic 10 parts of a surfactant (Neogen SC: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) dissolved in 550 parts of ion-exchanged water is emulsified and dispersed in a flask, and slowly mixed for 10 minutes. 50 parts of ion-exchanged water in which was dissolved was added. After carrying out nitrogen substitution, while stirring the inside of the flask, it was heated in an oil bath until the contents reached 70 ° C., and emulsion polymerization was continued for 5 hours. As a result, a resin particle dispersion was prepared in which resin particles having a volume average particle size of 154 nm, a glass transition temperature Tg of 59 ° C., and a weight average molecular weight Mw of 15700 were dispersed. The solid content concentration of this dispersion was 40% by weight.

(Preparation of colorant dispersion (1))
Carbon black (Mogal L: manufactured by Cabot) 60 parts, nonionic surfactant (Nonpol 400: manufactured by Sanyo Chemical Co., Ltd.) 6 parts, and ion-exchanged water 240 parts were mixed and dissolved into a homogenizer (Ultra Turrax). (T50: manufactured by IKA Co., Ltd.) for 10 minutes, and then, a colorant dispersion (1) in which colorant (carbon black) particles having a volume average particle size of 250 nm are dispersed by an optimizer. Was prepared.

(Preparation of release agent dispersion)
100 parts of paraffin wax (HNP0190: manufactured by Nippon Seiwa Co., Ltd., melting point: 85 ° C.), 5 parts of cationic surfactant (Sanisol B50: manufactured by Kao Corporation), and 240 parts of ion-exchanged water are mixed and heated to 95 ° C. In a round stainless steel flask, after dispersing for 10 minutes using a homogenizer (Ultra Turrax T50: manufactured by IKA), a release agent particle having a volume average particle diameter of 550 nm is dispersed by a pressure discharge type homogenizer. A mold release agent dispersion liquid was prepared.

(Production of toner particle K1 and toner particle external additive K1A)
234 parts of resin fine particle dispersion, 30 parts of colorant dispersion (1), 40 parts of release agent dispersion, 1.9 parts of polyaluminum hydroxide (Pho2S manufactured by Asada Chemical Co., Ltd.), and 600 parts of ion-exchanged water, After mixing and dispersing in a round stainless steel flask using a homogenizer (Ultra Turrax T50: manufactured by IKA), the flask was heated to 55 ° C. with stirring in an oil bath for heating. After holding at 55 ° C. for 40 minutes, it was confirmed that aggregated particles having a volume average particle diameter D50 of 5.0 μm were produced. Furthermore, when the temperature of the heating oil bath was raised and maintained at 56 ° C. for 2 hours, the volume average particle diameter D50 of the aggregated particles was 6.2 μm.

  Thereafter, 34 parts of the resin fine particle dispersion was added to the dispersion containing the aggregated particles, and then the temperature of the heating oil bath was set to 51 ° C. and held for 30 minutes. After the pH of the system is adjusted to 7.0 by adding a 1N sodium hydroxide solution to the dispersion containing the aggregated particles, the stainless steel flask is sealed, and the stirring is continued to 80 ° C. using a magnetic seal. Heated and held for 3.5 hours. After cooling, the reaction product was filtered off, washed four times with ion exchange water, and then freeze-dried to produce toner particles K1. The volume average particle diameter D50 of the toner particles K1 is 6.6 μm, the average value of the shape factor SF1 is 134, and the true specific gravity is 1.1.

  In order to externally treat the toner particles K1, silica (produced by a gas phase oxidation method, volume average particle size 40 nm, true specific gravity 2.2, silicone oil treatment), rutile type titanium oxide (volume average particle size 20 nm, true specific gravity). (4.2, n-decyltrimethoxysilane treatment), the addition amount was calculated by the following formula (2) so that the coverage was 20% silica and 10% titanium oxide, respectively.

C = A × (2π / √3) × (da / dt) × (ρa / ρt) ÷ 100 (2)
The symbols in the above formula (2) are as follows.
C: Weight of external additive / particle weight A: Toner surface coverage of external additive [%]
da: Volume average particle diameter of external additive [μm]
dt: Volume average particle diameter of particles (D50) [μm]
ρa: True specific gravity of external additive ρt: True specific gravity of particles

  That is, 0.88 part of silica and 0.42 part of titanium oxide per 100 parts of toner particles K1. These toner particles K1: 100 parts, silica 0.88 parts, titanium oxide 0.42 parts were blended for 15 minutes at a peripheral speed of 30 m / s using a 5 liter Henschel mixer, and then a sieve having an opening of 45 μm was used. Thus, coarse particles were removed to obtain toner particle external additive K1A.

(Production of toner particle K2 and toner particle external additive K2A)
234 parts of resin fine particle dispersion, 30 parts of colorant dispersion (1), 40 parts of release agent dispersion, 1.0 part of polyaluminum hydroxide (Poso2S manufactured by Asada Chemical Co., Ltd.), and 600 parts of ion-exchanged water, After mixing and dispersing in a round stainless steel flask using a homogenizer (Ultra Turrax T50: manufactured by IKA), the flask was heated to 40 ° C. with stirring in a heating oil bath. After maintaining at 40 ° C. for 30 minutes, it was confirmed that aggregated particles having a volume average particle diameter D50 of 4.7 μm were formed. Further, when the temperature of the heating oil bath was raised and held at 55 ° C. for 1 hour, the volume average particle diameter D50 of the aggregated particles was 5.3 μm.

  Thereafter, 26 parts of the resin fine particle dispersion was added to the dispersion containing the aggregated particles, and then the temperature of the heating oil bath was set to 50 ° C. and held for 30 minutes. A 1N sodium hydroxide solution is added to the dispersion containing the aggregated particles to adjust the pH of the system to 7.0, and then the stainless steel flask is sealed, and stirring is continued using a magnetic seal at 80 ° C. And heated for 4 hours. After cooling, the reaction product was filtered off, washed four times with ion exchange water, and then lyophilized to produce toner particles K2. The volume average particle diameter D50 of the toner particles K2 is 5.7 μm, the average value of the shape factor SF1 is 131, and the true specific gravity is 1.1.

  In order to externally treat the toner particles K2 in the same manner as K1A, silica (produced by a gas phase oxidation method, volume average particle size 40 nm, true specific gravity 2.2, silicone oil treatment), rutile type titanium oxide (volume average particle size 20 nm). , True specific gravity 4.2, n-decyltrimethoxysilane treatment), the addition amount was calculated by the formula (2) so that the coverage was 20% silica and 10% titanium oxide, respectively. The respective calculated amounts are shown in Table 1.

  To the toner particles K2: 100 parts, silica and titanium oxide are added as shown in Table 1, blended for 15 minutes at a peripheral speed of 30 m / s using a 5 liter Henschel mixer, and then using a sieve having a mesh opening of 45 μm. Coarse particles were removed to obtain toner particle external additive K2A.

(Production of toner particle K3 and toner particle external additive K3A)
100 parts of polyester resin (linear polyester obtained from terephthalic acid, bisphenol A ethylene oxide adduct and cyclohexanedimethanol, glass transition temperature Tg: 62 ° C., number average molecular weight Mn: 13000, weight average molecular weight Mw: 34000), A mixture of 4 parts of carbon black (Mogal L: Cabot) and 7 parts of carnauba wax is kneaded with an extruder, pulverized with a jet mill, and then classified with a wind classifier turbo classifier (manufactured by Nisshin Flour Milling). A toner particle K3 having a volume average particle diameter D50 of 6.3 μm, an average value of the shape factor SF1 of 141, and a true specific gravity of 1.1 was produced.

  In order to externally treat the toner particles K3 in the same manner as K1A, silica (prepared by a gas phase oxidation method, volume average particle size 40 nm, true specific gravity 2.2, silicone oil treatment), rutile titanium oxide (volume average particle size 20 nm). , True specific gravity 4.2, n-decyltrimethoxysilane treatment), the addition amount was calculated by the formula (2) so that the coverage was 20% silica and 10% titanium oxide, respectively. The respective calculated amounts are shown in Table 1.

  To 100 parts of toner particles K3, silica and titanium oxide were added as shown in Table 1, blended for 15 minutes at a peripheral speed of 30 m / s using a 5 liter Henschel mixer, and then using a sieve having a 45 μm mesh. Coarse particles were removed to obtain toner particle external additive K3A.

(Production of toner particle K4 and toner particle external additive K4A)
100 parts of polyester resin (linear polyester obtained from terephthalic acid, bisphenol A ethylene oxide adduct and cyclohexanedimethanol, glass transition temperature Tg: 62 ° C., number average molecular weight Mn: 13000, weight average molecular weight Mw: 34000), A mixture of 4 parts of carbon black (Mogal L: Cabot) and 7 parts of carnauba wax is kneaded with an extruder, pulverized with a jet mill, and then spheronized with hot air at Kryptron (manufactured by Kawasaki Heavy Industries). After that, it was classified with a wind classifier to produce toner particles K4 having a volume average particle diameter D50 of 6.4 μm, an average value of shape factor SF1 of 128, and a true specific gravity of 1.1.

  In order to externally add the toner particles K4 in the same manner as K1A, silica (prepared by vapor phase oxidation method, volume average particle size 40 nm, true specific gravity 2.2, silicone oil treatment), rutile type titanium oxide (volume average particle size 20 nm, True specific gravity 4.2, n-decyltrimethoxysilane treatment), and the amount of addition of formula (2) was calculated so that the coverage was 20% silica and 10% titanium oxide, respectively. The respective calculated amounts are shown in Table 1.

  To 100 parts of toner particles K4, silica and titanium oxide are added as shown in Table 1, blended for 15 minutes at a peripheral speed of 30 m / s using a 5 liter Henschel mixer, and then using a sieve having a 45 μm mesh. Coarse particles were removed to obtain toner particle external additive K4A.

(Production of toner particle K5 and toner particle external additive K5A)
100 parts of a polyester resin (linear polyester obtained from terephthalic acid, bisphenol A ethylene oxide adduct and cyclohexanedimethanol, glass transition temperature Tg: 62 ° C., number average molecular weight Mn: 13000, weight average molecular weight Mw: 33000), A mixture of 4 parts of carbon black (Mogal L: Cabot) and 7 parts of carnauba wax is kneaded with an extruder, pulverized with a jet mill, and then classified with a wind classifier turbo classifier (manufactured by Nisshin Flour Milling). A toner particle K5 having a volume average particle diameter D50 of 9.3 μm, an average value of the shape factor ML ² / A of 140, and a true specific gravity of 1.1 was produced.

  In order to externally treat the toner particles K5 in the same manner as K1A, silica (prepared by vapor phase oxidation method, volume average particle size 40 nm, true specific gravity 2.2, silicone oil treatment), rutile type titanium oxide (volume average particle size 20 nm). , True specific gravity 4.2, n-decyltrimethoxysilane treatment), the addition amount was calculated by the formula (2) so that the coverage was 20% silica and 10% titanium oxide, respectively. The respective calculated amounts are shown in Table 1.

  To 100 parts of toner particles K5, silica and titanium oxide are added as shown in Table 1, blended for 15 minutes at a peripheral speed of 30 m / s using a 5 liter Henschel mixer, and then using a sieve having a 45 μm mesh. Coarse particles were removed to obtain toner particle external additive K5A.

(Production of toner particle K6 and toner particle external additive K6A)
100 parts of a polyester resin (linear polyester obtained from terephthalic acid, bisphenol A ethylene oxide adduct and cyclohexanedimethanol, glass transition temperature Tg: 62 ° C., number average molecular weight Mn: 13000, weight average molecular weight Mw: 33000), A mixture of 4 parts of carbon black (Mogal L: Cabot Corp.) and 7 parts of carnauba wax was kneaded with an extruder, pulverized with a jet mill, and then spheronized with hot air was carried out with Kryptron (Kawasaki Heavy Industries). Thereafter, it is classified by a wind classifier turbo classifier (manufactured by Nisshin Flour Milling Co., Ltd.), and toner particles K6 having a volume average particle diameter D50 of 9.0 μm, an average value of the shape factor ML ² / A of 130, and a true specific gravity of 1.1. Was made.

  In order to externally treat the toner particles K6 in the same manner as K1A, silica (prepared by vapor phase oxidation method, volume average particle size 40 nm, true specific gravity 2.2, silicone oil treatment), rutile type titanium oxide (volume average particle size 20 nm). , True specific gravity 4.2, n-decyltrimethoxysilane treatment), the addition amount was calculated by the formula (2) so that the coverage was 20% silica and 10% titanium oxide, respectively. The respective calculated amounts are shown in Table 1.

  To 100 parts of toner particles K6, silica and titanium oxide were added as shown in Table 1, blended for 15 minutes at a peripheral speed of 30 m / s using a 5 liter Henschel mixer, and then using a sieve having a 45 μm mesh. Coarse particles were removed to obtain toner particle external additive K6A.

<Preparation of amorphous particles>
(Amorphous particles A)
Polymer alcohol (linear alcohol with an average carbon number of 85) is kneaded with a Banbury mixer, coarsely pulverized with a hammer mill, and finely pulverized with a jet mill. The volume average particle diameter D50 is 8.1 μm, and the true specific gravity is 1. 0.0 amorphous particles A were obtained.

(Amorphous particle A1)
Coarse particles were removed from the irregular shaped particles A using a sieve having an opening of 45 μm to obtain irregular shaped particles A1. At that time, the average value of the shape factor SF1 was 147, and the volume average particle diameter D50 was 8.0 μm.

(Amorphous particle A2)
In order to externally treat the amorphous particles A, silica (prepared by a gas phase oxidation method, volume average particle size 40 nm, true specific gravity 2.2, silicone oil treatment), rutile titanium oxide (volume average particle size 20 nm, true For specific gravity 4.2 and n-decyltrimethoxysilane treatment, the addition amount was calculated by the above formula (2) so that the coverage was 20% silica and 10% titanium oxide, respectively.

  That is, 0.40 part of silica and 0.19 part of titanium oxide with respect to 100 parts of amorphous particles A. These irregular shaped particles A: 100 parts, 0.40 parts of silica and 0.19 parts of titanium oxide were blended for 15 minutes at a peripheral speed of 30 m / s using a 5-liter Henschel mixer, and then a sieve having an opening of 45 μm was obtained. Using this, coarse particles were removed to obtain amorphous particles A2. Table 2 shows the average value of the shape factor SF1 and the volume average particle diameter D50 at that time.

(Amorphous particles A3 to A13)
Amorphous particles A: Amorphous particles similar to the adjustment of A2, except that 100 parts of silica and titanium oxide were coated using the formula (2) based on the coverage of silica and titanium oxide as shown in Table 2. A3 to A13 were obtained. Table 2 shows the average value of the shape factor SF1 and the volume average particle diameter D50 at that time.

(Irregular particles B)
Polymer alcohol (linear alcohol having an average carbon number of 120) is kneaded with a Banbury mixer, coarsely pulverized with a hammer mill, and finely pulverized with a jet mill. The volume average particle diameter D50 is 9.9 μm, and the true specific gravity is 1. 0.0 amorphous particles B were obtained.

(Amorphous particles B1, B2)
Amorphous particles B: Amorphous particles as in the adjustment of A2, except that 100 parts of silica and titanium oxide were coated using the formula (2) based on the coating ratio and the coating ratio as shown in Table 2. B1 to B2 were obtained. Table 2 shows the average value of the shape factor SF1 and the volume average particle diameter D50 at that time.

(Irregular particle C)
Polymer alcohol (linear alcohol with an average carbon number of 50) is kneaded with a Banbury mixer, coarsely pulverized with a hammer mill, and finely pulverized with a jet mill. The volume average particle diameter D50 is 12.1 μm, and the true specific gravity is 1. 0.0 amorphous particles C were obtained.

(Amorphous particle C1)
Amorphous particles C: Amorphous particles similar to the adjustment of A2 except that the amount of silica and titanium oxide covered with 100 parts and the amount calculated from the coverage using Equation (2) is as shown in Table 2. C1 was obtained. Table 2 shows the average value of the shape factor SF1 and the volume average particle diameter D50 at that time.

(Irregular particles D)
Polymer alcohol (linear alcohol with an average carbon number of 210) is kneaded with a Banbury mixer, coarsely pulverized with a hammer mill, and finely pulverized with a jet mill. The volume average particle diameter D50 is 19.1 μm, and the true specific gravity is 1. 0.0 amorphous particles D were obtained.

(Irregular particle D1)
Amorphous particles D: Amorphous particles as in the adjustment of A2, except that 100 parts of silica and titanium oxide were coated using the formula (2) based on the coverage of silica and titanium oxide as shown in Table 2. D1 was obtained. Table 2 shows the average value of the shape factor SF1 and the volume average particle diameter D50 at that time.

(Irregular particles E)
A styrene-nbutyl acrylate copolymer (monomer ratio 8: 2, Tg = 58 ° C., weight average molecular weight = Mw: 12500) was kneaded with a Banbury mixer, coarsely pulverized with a hammer mill, and finely pulverized with a jet mill. An irregular-shaped particle E having a volume average particle diameter D50 of 8.2 μm and a true specific gravity of 1.1 was obtained.

(Irregular particles E1)
Coarse particles were removed from the irregular shaped particles E using a sieve having an opening of 45 μm to obtain irregular shaped particles E1. The average value of the shape factor SF1 at that time shows the volume average particle diameter D50 in Table 2.

(Amorphous particles E2 to E4)
Amorphous particles E: Amorphous particles as in the adjustment of A2, except that 100 parts of silica and titanium oxide were coated using the formula (2) based on the coating ratio and the coating ratio as shown in Table 2. E2 to E4 were obtained. Table 2 shows the average value of the shape factor SF1 and the volume average particle diameter D50 at that time.

(Irregular particles F)
A styrene-nbutyl acrylate copolymer (monomer ratio 8: 2, Tg = 58 ° C., weight average molecular weight Mw = 12,500) was kneaded with a Banbury mixer, coarsely pulverized with a hammer mill, and finely pulverized with a jet mill. An irregular particle F having a volume average particle diameter D50 of 5.2 μm and a true specific gravity of 1.1 was obtained.

(Irregular particle F1)
The irregular particles F were removed using coarse sieves having a mesh size of 45 μm to obtain irregular particles F1. The average value of the shape factor SF1 at that time shows the volume average particle diameter D50 in Table 2.

(Amorphous particles F2 to F3)
Amorphous particles F: Amorphous particles similar to the adjustment of A2, except that the coverage calculated with 100 parts of silica and titanium oxide and the amount calculated from the coverage using Formula (2) are as shown in Table 2. F2 to F3 were obtained. Table 2 shows the average value of the shape factor SF1 and the volume average particle diameter D50 at that time.

(Irregular particles G)
80 parts of styrene-nbutyl acrylate copolymer (monomer ratio 8: 2, Tg = 58 ° C., weight average molecular weight Mw = 12,500) and 20 parts of zinc stearate are kneaded with a Banbury mixer, and then coarsely pulverized with a hammer mill. By pulverizing with a jet mill, amorphous particles G having a volume average particle diameter D50 of 5.2 μm and a true specific gravity of 1.1 were obtained.

(Amorphous particle G1)
Coarse particles were removed from the irregular shaped particles G using a sieve having an opening of 45 μm to obtain irregular shaped particles G1. The average value of the shape factor SF1 at that time shows the volume average particle diameter D50 in Table 2.

(Amorphous particles G2 to G3)
Amorphous particles G: Amorphous particles in the same manner as in A2 except that 100 parts of silica and titanium oxide were coated using the formula (2) based on the coating ratio and the coating ratio as shown in Table 2. G2 to G3 were obtained. Table 2 shows the average value of the shape factor SF1 and the volume average particle diameter D50 at that time.

(Irregular particles H)
After kneading polymer alcohol (linear alcohol with average carbon number of 100) with a Banbury mixer, coarsely pulverizing with a hammer mill and finely pulverizing with a jet mill, spheronization with warm air is performed by Kryptron (manufactured by Kawasaki Heavy Industries) The amorphous particles H having a volume average particle diameter D50 of 8.0 μm and a true specific gravity of 1.0 were obtained.

(Irregular particles H1)
Amorphous particles H: 100 parts by weight of silica and titanium oxide, and the amount calculated using the formula (2) based on the coverage as shown in Table 2 is the same as in A2 adjustment. H1 was obtained. Table 2 shows the average value of the shape factor SF1 and the volume average particle diameter D50 at that time.

(Irregular particles I)
The amorphous particles H are further spheronized with warm air using Kryptron (manufactured by Kawasaki Heavy Industries) to obtain amorphous particles I having a volume average particle diameter D50 of 8.0 μm and a true specific gravity of 1.0. It was.

(Irregular particles I1)
Amorphous particles I: Amorphous particles as in the adjustment of A2, except that 100 parts of silica and titanium oxide were coated using the formula (2) based on the coverage of silica and titanium oxide as shown in Table 2. I1 was obtained. Table 2 shows the average value of the shape factor SF1 and the volume average particle diameter D50 at that time.

<Creation of carrier>
17 parts of toluene, 3 parts of styrene-methacrylate copolymer (component ratio: 25/75), and 0.4 parts of carbon black (R330: manufactured by Cabot) were mixed and stirred with a stirrer for 10 minutes. A dispersed coating layer forming solution was prepared. Next, this coating solution and 100 parts of ferrite particles (volume average particle size: 38 μm) are put in a vacuum degassing kneader and stirred at 60 ° C. for 30 minutes, and then degassed by further reducing pressure while heating. The carrier was prepared by drying. This carrier had a volume resistivity of 10 ^15.5 Ωcm when an electric field of 1000 V / cm was applied.

<Comparative Example 1>
Toner particle external additive K1A: 0.5 part of the irregular shaped particle A1 is added to 100 parts, and blended for 1 minute at a peripheral speed of 5 m / s using a 5 liter Henschel mixer, and then the opening of 45 μm is obtained. Coarse particles were removed using a sieve to produce a toner. Further, 92 parts of the carrier and 8 parts of the toner were stirred at 40 rpm for 20 minutes with a V-blender, and sieved with a sieve having a mesh size of 212 μm for 5 minutes at 3 Hz for 5 minutes to develop for electrophotography. An agent was prepared.
The charge amount of the whole toner was 53.9 μC / g, and the charge amount of the amorphous particles A1 was 2.7 μC / g.

<Examples 1-17, Comparative Examples 2-17>
A toner was prepared in the same manner as in Comparative Example 1 except that the toner particles, the irregularly shaped particles to be added, and the amount thereof added in Comparative Example 1 are as shown in Table 3. The mixture was stirred for 20 minutes at 40 rpm with a V-blender, and sieved with a sieve having an opening of 212 μm to prepare a developer for developing an electrostatic image. Table 3 shows the charge amount of the entire toner, the charge amount of the amorphous particles, and the ratio thereof.

<Example 18>
To 100 parts of the toner particles K1, silica (prepared by vapor phase oxidation method, volume average particle size 40 nm, true specific gravity 2.2, silicone oil treatment), rutile type titanium oxide (volume average particle size 20 nm, true specific gravity 4. 2, n-decyltrimethoxysilane treatment), the addition amount was calculated by the above formula (2) so that the coverage was 20% silica and 10% titanium oxide, respectively.

  That is, 0.81 part of silica and 0.42 part of titanium oxide per 100 parts of toner particles K. After blending these toner particles K1: 100 parts, silica 0.88 parts, titanium oxide 0.42 parts and further amorphous particles A 0.5 parts at a peripheral speed of 30 m / s for 15 minutes using a 5-liter Henschel mixer. Coarse particles were removed using a sieve having an opening of 45 μm to prepare a toner. An electrophotographic developer was prepared by stirring 8 parts of the toner and 92 parts of the carrier with a V-blender for 20 minutes at 40 rpm and sieving with a sieve having an opening of 212 μm. Table 3 shows the charge amount of the entire toner, the charge amount of the amorphous particles, and the ratio thereof.

<Evaluation of actual machine>
Using each of the above developers, the Docu Center has been modified so that the toner collected in the cleaning process is transported by the auger from the collection box for collecting the collected toner back to the developing unit and fed into the developing unit. Each color was evaluated by the following method using Color 400CP (manufactured by Fuji Xerox Co., Ltd.).

(Evaluation of initial developability and initial transferability)
In a low-temperature and low-humidity environment (10 ° C., 20% RH), a solid patch of 5 cm × 2 cm is developed for each color, and the developed toner image on the surface of the photoreceptor is transferred using the adhesiveness of the tape surface. The weight (W1) was measured. Next, the same developed toner image was transferred onto the surface of paper (J paper: manufactured by Fuji Xerox Office Supply), and the weight (W2) of the transferred image was measured. From these, the transfer efficiency was determined by the following formula, and the transferability was evaluated.
Transfer efficiency (%) = (W2 / W1) × 100
The developability was evaluated based on the weight of W1 at this time.

-Initial developability evaluation criteria-
・ ○: W1 is 4.5 g / m ² or more and less than 6.0 g / m ²・ Δ: W1 is 6.0 g / m ² or more and less than 6.5 g / m ²・ ×: W1 is 6.5 g / m ² or more Or less than 4.5 g / m ²

-Initial transferability evaluation criteria-
・ ○: Transfer efficiency is 90% or more ・ △: Transfer efficiency is 85% or more and less than 90% ・ ×: Transfer efficiency is less than 85%

-Initial transfer unevenness evaluation criteria-
• ○: There is no visual unevenness in the halftone image. ×: There is unevenness visible in the halftone image.

(Evaluation of cleaning / developability / transfer maintenance at the time of reclaim)
In a low-temperature, low-humidity (10 ° C, 20% RH) environment, use J paper (manufactured by Fuji Xerox Office Supply) to print 100000 sheets at an image density of 10%, and then develop using the same method and the following evaluation criteria. Evaluation of maintainability / transfer unevenness maintainability was performed. In addition, it was confirmed whether or not there was a cleaning failure during printing 1 to 100,000 sheets, and image quality deterioration due to photoconductor wear. Further, after taking 10,000 prints in a high temperature and high humidity (30 ° C., 80% RH) environment, the toner cloud was confirmed according to the following evaluation criteria.

-Evaluation criteria for maintainability of developability-
・ ○: W1 is 4.5 g / m ² or more and less than 6.0 g / m ²・ Δ: W1 is 6.0 g / m ² or more and less than 6.5 g / m ²・ ×: W1 is 6.5 g / m ² or more Or less than 4.5 g / m ²

-Evaluation criteria for transfer unevenness maintenance-
・ ○: Halftone image has no visible unevenness ・ ×: Halftone image has visible unevenness

-Toner cloud evaluation criteria-
• ○: The charger and the machine are not dirty, and the print sample is not dirty.
X: The charger and the inside of the machine are very dirty, and it can be visually observed that the print sample is also dirty.
The results are shown in Table 4.

  As described above, the improvement in the reliability by reducing the friction between the blade and the photosensitive member can be achieved in a balanced manner without causing image quality defects such as image unevenness while improving the cleaning property. In particular, in the toner reclaim system in which the transfer residual toner collected in the cleaning process is returned to the developing unit and the toner is reused, in order to obtain the high-quality image, both the cleaning property and the long-term developing property are achieved. The purpose of avoiding image quality defects such as image unevenness could be achieved in a balanced manner.

Claims (2)

A step of forming a latent image on the latent image carrier, a development step of converting the latent image into a toner image using a developer on the developer carrier, a transfer step of transferring the toner image, and the latent image carrier; In the developer for developing an electrostatic charge image used in the toner reclaim method in which an image is formed by a cleaning process for removing toner remaining in the toner, and the toner removed in the cleaning process is returned to the developing process.
The developer for developing an electrostatic charge image includes a toner and a carrier. The toner includes toner particles having a shape factor SF1 of 120 or more and less than 140, and irregular particles having a shape factor SF1 of 140 or more. When the volume average particle diameter of the regular particles is in the range of 1 to 10 μm, the charge amount between the irregular particles and the carrier is X, and the charge amount between the toner and the carrier is Y, 0.5 ≦ X /Y≦1.4 developer for developing an electrostatic charge image. A step of forming a latent image on the latent image carrier, a development step of converting the latent image into a toner image using a developer on the developer carrier, a transfer step of transferring the toner image, and a residual image on the latent image carrier. In an image forming method including a cleaning step for removing toner to be removed, and a toner reclaim step for returning the toner removed in the cleaning step to a development step,
The developer includes a toner and a carrier, and the toner includes toner particles having a shape factor SF1 of 120 or more and less than 140, and amorphous particles having a shape factor SF1 of 140 or more. The volume average of the amorphous particles When the particle size is in the range of 1 to 10 μm, the charge amount between the amorphous particles and the carrier is X, and the charge amount Y between the toner and the carrier is 0.5 ≦ X / Y ≦ 1.4. An image forming method, which is a developer for developing an electrostatic image.