JP4375222B2 - Electrostatic latent image developer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic latent image developer with which an image of high image quality can be stably obtained by suppressing an image defect and roughness of the image and the contamination within the machine. <P>SOLUTION: The electrostatic latent image developer composed of an electrostatic latent image developing toner and a carrier is characterized in that the electrostatic latent image developing toner has coloring particles containing at least a binder resin, a colorant and a release agent, and an external additive; the average circularity of the toner is &ge;0.940 to &lt;0.970; the value of cumulative 90% of an arithmetic mean height distribution is &ge;0.15 &mu;m; and the median of the arithmetic mean height distribution of the carrier is 0.20 to 0.40 &mu;m. <P>COPYRIGHT: (C)2006,JPO&amp;NCIPI

Description

  The present invention relates to an electrostatic latent image developer used for developing an electrostatic latent image in electrophotography and electrostatic recording.

2. Description of the Related Art Conventionally, in an image forming apparatus such as an electrophotographic type or electrostatic recording type copying machine, a developing method for developing an electrostatic latent image formed on a latent image carrier such as a photosensitive drum is used. Conventionally, various apparatuses for dry development in a recording apparatus such as an electronic copying machine have been proposed and put into practical use. The development methods are roughly classified according to the developer components, and can be divided into a one-component method and a two-component method.
Unlike the one-component development method using a magnetic toner, the two-component development method uses a magnetic carrier to convey the toner, but a non-magnetic toner can be used so that a color image can be obtained and the image quality is also high. For this reason, a two-component development method using a two-component developer has been widely adopted.

  In this two-component development method, a two-component developer composed of a magnetic carrier having a magnetic material and a non-magnetic toner mainly composed of resin is accommodated in a development housing having an opening for development, and the two-component developer is contained in the development housing. The developer is stirred, and the toner is charged by frictional charging between the magnetic carrier and the nonmagnetic toner. At the same time, a developer layer composed of a two-component developer is formed on the developing sleeve, and only the developing sleeve is driven to rotate, and the two-component developer composed of the charged non-magnetic toner and the magnetic carrier is adhered and conveyed to the outer peripheral surface of the developing sleeve. The two-component developer attached to the developing sleeve is brought into contact with the latent image carrier on which the electrostatic latent image is formed, so that the toner is attached to the electrostatic latent image portion and visualized as a toner image. It has become.

  It is also necessary to obtain a sufficient image density in order to satisfy the demand for high image quality. As a means for obtaining a sufficient image density in the two-component development system, a developing region in which the developing sleeve and the latent image carrier are close to each other by applying a bias containing an AC component between the developing roll and the latent image carrier. It has been proposed to form an oscillating electric field and to attach a charged toner to the electrostatic latent image by the oscillating electric field (see Patent Document 1).

  However, in the two-component development method as described above, the developer layer (developer brush) attached to the developing sleeve is brought into contact with the latent image carrier on which the electrostatic latent image is formed. The toner image developed above is disturbed by the two-component developer adhering to the developing sleeve to cause an image defect, or the uniformity of the toner image is lost and the image is liable to be crumpled. It was difficult. This image defect is conspicuous especially for an intermediate density image, and is one problem for achieving high image quality.

  As means for preventing these occurrences, for example, a repulsive magnetic field is formed on a magnet roll corresponding to the development area (see Patent Document 2), or a soft developer layer is formed using a magnetic carrier having a low magnetic susceptibility (Patent Document 2). Documents 3 and 4) have been proposed. These inventions use a technique of weakening the magnetic binding force of the developer layer to soften the developer brush in the development area where the developer toner is developed, and develop the toner image developed on the latent image carrier. By trying to reduce the shearing force of contact between the toner and the two-component developer adhering to the developing sleeve, an attempt is made to prevent image defects and roughness. However, in any aspect, it is difficult to avoid a situation in which the magnetic carrier is transferred from the developing roll to the latent image carrier side because the technique of weakening the magnetic binding force of the developer layer is used. In addition, the magnetic carrier easily adheres to the latent image carrier, and the carrier damages the latent image carrier or is fixed to a medium such as paper together with toner, causing another type of image defect.

  Also, due to the problem of higher image quality, attempts have been made to reduce the toner particle size and increase the reproducibility to the image faithfully. However, as the toner particle size becomes smaller, the surface area per unit weight becomes smaller. The amount of electric charge of the toner tends to increase, the adhesion between the toners and the toner and the carrier is strong, the fluidity of the two-component developer decreases, the developer brush becomes hard, and the above-mentioned image defects and roughness Etc. were promoted.

  On the other hand, when the fluidity of the two-component developer is too good, the contact between the non-magnetic toner and the magnetic carrier becomes weak, the non-magnetic toner slips on the magnetic carrier, and the frictional charging between the two is stable. There was a problem of not happening. Furthermore, when the nonmagnetic toner slips on the magnetic carrier, the holding force of the nonmagnetic toner on the magnetic carrier is weakened. The centrifugal force caused by the rotation of the developing sleeve is restrained by the developing sleeve by a magnetic force on the magnetic carrier, but the nonmagnetic toner is held by an electric attractive force with the magnetic carrier. Therefore, when the holding force of the nonmagnetic toner on the magnetic carrier is weakened, the toner is scattered from the developing sleeve. The toner scattered from the developing sleeve floats inside the machine and contaminates various parts inside the machine. In particular, when the toner adheres to a non-image portion of the latent image carrier or contaminates the optical writing device to the latent image carrier, an image defect occurs.

Japanese Patent Laid-Open No. 62-192758 Japanese Patent Publication No. 3-14178 JP 59-104663 A Japanese Examined Patent Publication No. 2-56774

  An object of the present invention is to solve the conventional problems and achieve the following objects. That is, the present invention provides an electrostatic latent image developer capable of suppressing image defects, image roughness, and contamination inside the machine, and capable of stably obtaining a high-quality image, and an image forming method using the same. The purpose is to do.

As a result of extensive research, the present inventors have found that the above problem can be solved by controlling the surface roughness (arithmetic average height) and surface roughness distribution of the toner and carrier. The invention has been completed. It is described below with preferred embodiments.
(1) An electrostatic latent image developer comprising an electrostatic latent image developing toner and a carrier, wherein the electrostatic latent image developing toner is a color containing at least a binder resin, a colorant and a release agent. Particles having an external additive, the average circularity of the toner is 0.940 or more and less than 0.970, the cumulative 90% value of the arithmetic average height distribution of the toner is 0.15 μm or more, An electrostatic latent image developer, wherein the median of the arithmetic average height distribution of the carrier is 0.20 μm or more and 0.40 μm or less;
(2) The electrostatic latent image developer according to (1), wherein the arithmetic average height variation of the carrier is 30 or less,
(3) The electrostatic latent image developer according to (1) or (2), wherein the 90% cumulative value of the arithmetic average height distribution of the carrier is less than 0.5 μm,
(4) A step of forming an electrostatic latent image on the electrostatic latent image carrier, and developing the electrostatic latent image on the electrostatic latent image carrier with an electrostatic latent image developer containing toner to form a toner image. Forming the toner image, transferring the toner image, and fixing the toner image, wherein the developer is any one of (1) to (3). An electrostatic latent image developer is used.

  As described above, by controlling the surface roughness of the carrier (median average height / variation / cumulative 90% value), the fluidity of the developer is improved and the magnetic brush on the developing sleeve is softened. Further, it is possible to prevent image defects and roughness that are caused by the toner image developed on the latent image carrier being disturbed by the two-component developer attached to the developing sleeve. Furthermore, by controlling the toner surface roughness (cumulative value of 90%) and combining with the carrier, toner scattering from the developing sleeve can be prevented, and contamination inside the machine can be prevented.

Hereinafter, the present invention will be described in detail.
<Toner for electrostatic latent image development>
The electrostatic latent image developing toner of the present invention is an electrostatic latent image developer comprising an electrostatic latent image developing toner and a carrier, and the electrostatic latent image developing toner comprises a binder resin and a colorant. In addition, the toner has a color particle containing at least a release agent and an external additive. The toner has an average circularity of 0.940 or more and less than 0.970, and a 90% cumulative value of the arithmetic average height distribution is 0.15 μm. That's it.
In this way, by controlling the average circularity and arithmetic average height of the toner and distributing the toner having a large uneven surface structure of the toner in the toner, the contact area with the carrier is ensured, and the carrier and the toner slip Can be prevented. As a result, toner scattering from the developing sleeve can be prevented, and contamination inside the machine can be prevented.

  A cumulative 90% value of the arithmetic average height distribution of the toner of the present invention is 0.15 μm or more. In the arithmetic average height distribution, if the presence of a toner having an arithmetic average height of 0.15 μm or more is 10% or less, the surface property of the toner itself is also smooth, and in the combination with a carrier having a smooth surface according to the present invention. It is difficult to prevent the carrier and toner from slipping.

Here, the arithmetic average height of the toner is a physical quantity which is a surface roughness index and is generally expressed as Ra.
Ra is a value obtained by extracting a reference length from the roughness curve of the toner surface in the direction of the average line, and summing and averaging the absolute values of deviations from the average line of the extracted portion to the measurement curve. When the surface is smooth, a large value indicates a state with a large surface.
The median value of Ra is preferably 0.08 μm or more and 0.15 μm or less. The median value of Ra is preferably 0.08 μm or more, so that the liberation of the external additive can be reduced, and the median value of 0.15 μm or less is preferable because the external additive can be uniformly dispersed. Further, the variation of Ra is preferably 35% or more and 60% or less. When the variation of Ra is 35% or more, a certain degree of irregularities can be obtained in the surface property of the toner itself, and in the combination of the carrier with a smooth surface of the present invention, it is possible to prevent the carrier and the toner from slipping. Therefore, it is preferable. Further, it is preferable that the variation of Ra is 60% or less because the external additive can be uniformly dispersed.

The arithmetic average height of the toner was measured with an ultra-deep color 3D shape measuring microscope VK-9500 manufactured by Keyence Corporation. In this apparatus, a sample is irradiated with a laser to perform three-dimensional scanning. The laser reflected light at each position is monitored with a CCD camera to obtain three-dimensional surface information of the sample. The obtained surface information is statistically processed to obtain an index related to the surface roughness.
Here, 1,000 toners were measured, the data was statistically processed to determine the arithmetic average height distribution of the toner, and data such as the average value, median value, and standard deviation of the arithmetic average height were obtained. The fluctuation of the arithmetic average height referred to here is the percentage of the standard deviation with respect to the average value of the arithmetic average height.

Further, the average circularity of the toner of the present invention is 0.940 or more and less than 0.970. When the average circularity is 1.0, the sphere is a perfect sphere, and the lower the numerical value, the greater the irregularity.
When the average circularity is less than 0.940, the irregularity degree of the colored particles is increased and the surface area is increased. As the surface area increases, the contact area between the toner and the carrier increases, and the adhesion between the toner and the carrier increases. As the adhesive force increases, the developing brush becomes hard and image defects are likely to occur. On the other hand, when the average circularity is 0.970 or more, the continuity of gradation in the low image density region (highlight) is lost due to the reduced adhesion between the toner and the carrier, Toner released from the carrier may float inside the machine and cause machine contamination.

Here, the average circularity is a value obtained by performing image analysis on a certain number of toner particles, obtaining the circularity according to the following equation for each photographed toner particle, and averaging them.
Circularity = circle equivalent diameter perimeter / perimeter = [2 × (A × π) ^1/2 ] / PM
(In the above formula, A represents the projected area and PM represents the perimeter.)

  The number average particle diameter, the number average particle diameter variation, and the average circularity of the toner particles are analyzed for each of at least 5,000 toner particles using a flow type particle image analyzer FPIA-2100 (manufactured by Sysmex). Obtained by performing and statistical processing.

  The toner for developing an electrostatic latent image of the present invention has at least colored particles containing a binder resin, a colorant and a release agent, and an external additive, and further contains other components as necessary. Do it. These will be described later.

The number average particle diameter of the toner in the present invention is preferably in the range of 5.0 to 7.0 μm, and more preferably in the range of 5.5 to 6.5 μm. It is preferable that the number average particle diameter is in the above range since the surface area of the colored particles is appropriate, the electrostatic adhesion is weak, and good transfer efficiency is obtained. Further, it is preferable because toner is less scattered in the development process and the transfer process, the reproducibility of the electrostatic latent image is good, and high-quality image quality can be obtained.
In addition, it is preferable that the number average particle diameter is in the above range from the viewpoint of excellent color reproducibility in full-color image formation.

The number average particle size variation of the colored particles in the present invention is preferably 25 or less, more preferably 20 or less. When the number average particle diameter variation is large, the size difference between the small diameter colored particles and the large diameter colored particles increases. This difference in size increases the difference in surface area per colored particle. Since the surface charge density of the toner in the developing unit corresponds to the surface area, the difference in surface area per colored particle appears as a difference in charge amount per colored particle.
Therefore, when the number average particle diameter variation is 25 or less, the difference in charge amount per colored particle is small, and the difference in the optimum development / transfer electric field of each color particle due to the difference in charge amount is small. / It is preferable because development / transfer can be performed simultaneously under transfer conditions.

  The number average particle size variation is a value obtained by performing statistical processing on the measured value of the number average particle size for a certain number of colored particles and expressing the standard deviation with respect to the average value as a percentage. The specific measurement method is as described above.

Next, a toner manufacturing method in the present invention will be described.
The toner in the present invention can be prepared by a known kneading / pulverizing method, a chemical method such as emulsion polymerization or suspension polymerization, and the like, and a toner having excellent particle size distribution, shape, and the like in the present invention can be manufactured. From the viewpoints of yield, yield, and environmental load, it is preferable to produce a toner by an emulsion polymerization method. Here, the production method using the emulsion polymerization method will be described in detail.

  In the emulsion polymerization method, a resin dispersion using an ionic surfactant and a colorant dispersed in an ionic surfactant of opposite polarity are mixed to form heteroaggregation to form aggregated particles having a toner diameter (aggregation). Step), and then heated above the glass transition point of the resin to fuse and aggregate the aggregated particles (fusion step), and then wash and dry to produce a toner.

  In this method, by selecting the heating temperature condition and the like, not only the toner shape can be controlled from an indeterminate shape to a spherical shape, but also the arithmetic average height of the colored particles can be controlled. Even if the polarities of the colorant and the resin particles are the same, the same aggregated particles can be produced by adding a surfactant having the opposite polarity. Further, before the aggregated particle dispersion is heated to fuse the aggregated particles, another fine particle dispersion is added and mixed to adhere the fine particles to the surface of the original aggregated particles, and then the glass transition point of the resin. By employing the method of fusing by heating as described above, the layer structure from the surface of the toner to the inside can be controlled. Furthermore, this method makes it possible to coat the toner surface with a resin, coat with a charge control agent, and dispose wax or a colorant near the toner surface.

  At this time, it is important to control the particle size distribution, shape distribution and arithmetic mean height that the fine particles (adhered particles) of the fine particle dispersion added and mixed later adhere uniformly and steadily to the aggregated particle surface. It is. If the fine particles that should adhere are present in a free state, or once adhering, the particle size distribution and shape distribution are easily broadened, and the arithmetic average height also changes. When the particle size distribution is widened, especially fine powder strongly adheres to the photoreceptor during development and causes black spots, and the two-component developer easily causes carrier contamination and shortens the developer life. In the case of a one-component developer, it adheres to a developing roll, a charging roll, a trimming roll or a blade and contaminates it, causing deterioration in image quality. Furthermore, there is a problem of the particle size distribution in the toner as a major factor related to the deterioration of image quality and reliability.

  Further, when the toner is produced by the emulsion polymerization method, it is important to control the stirring conditions for the particle size distribution and the shape distribution. Since the viscosity of the dispersion rises during the formation of aggregated particles that are the base material and after the addition of adhering particles, the reaction vessel wall is stirred when the dispersion is stirred at a high shear rate using an inclined paddle type stirring blade for the purpose of uniform mixing Further, the adhesion of the aggregated particles to the stirring blade increases, so that the uniform particle size is hindered. In order to perform uniform stirring at a low shear rate, it is effective to use a stirring blade having a wide blade shape (flat plate blade) in the liquid depth direction.

  Furthermore, it is also effective to remove coarse powder by filtration using a filter bag having an opening of 10 μm after formation of aggregated particles, and it is also effective to perform multistage or repeated treatment as necessary. The influence of the particle size distribution and shape distribution on the image quality increases as the average particle size of the toner is smaller or the toner shape is closer to a sphere.

Usually, this agglomeration and fusion process mixes and agglomerates all together, so that the agglomerated particles can be fused in a uniform mixed state, and the toner composition becomes uniform from the surface to the inside. When the release agent is contained by the above method, the release agent is also present on the surface after the fusion, and external additives for generating filming and imparting fluidity are buried in the toner. This phenomenon is likely to occur.
Therefore, in the aggregation step, the balance of the amount of the ionic surfactant of each initial polarity is shifted in advance to form and stabilize the first-stage base aggregated particles below the glass transition point, and then the second stage. Add a fine particle dispersion treated with a polar and quantity surfactant so as to compensate for the balance deviation, and if necessary, below the glass transition point of the resin contained in the base aggregated particles or additional fine particles After being heated and stabilized slightly, the fine particles added in the second stage can be fused while adhering to the surface of the base aggregated particles by heating above the glass transition point. In addition, these agglomeration operations can be repeated several times stepwise, and as a result, the composition and physical properties can be changed stepwise from the surface to the inside of the toner particles, thereby controlling the toner structure. Is extremely easy.

For example, in the case of a color toner used for multicolor development, after the mother aggregated particles are made up of resin fine particles and colorant fine particles in the first stage, another resin fine particle dispersion is added and only the resin layer is added to the toner surface. By forming, the influence on the charging behavior by the colorant fine particles can be minimized. As a result, a difference in charging characteristics due to the type of colorant can be suppressed. Further, if the glass transition point of the resin added in the second stage is set high, the toner can be coated in a capsule shape, and both heat storage stability and fixing property can be achieved.
Furthermore, if a release agent fine particle dispersion such as wax is added in the second stage, and a shell is formed on the outermost surface using a dispersion of resin with high hardness in the third stage, the wax is exposed to the toner surface. It is also possible to prevent the wax from acting as a release agent during fixing.
Further, after the release agent fine particles are contained in the base aggregated particles, a shell may be formed on the outermost surface in the second stage to prevent the exposure of the wax. When the exposure of the wax is prevented, not only filming on the photoreceptor and the like is suppressed, but also the powder fluidity of the toner can be improved.

  As described above, in the method in which fine particles are attached stepwise to the surface of the aggregated particles and heated and fused, the maintenance of the particle size distribution and the shape distribution, the fluctuation of the average particle size and the circularity can be suppressed, and the aggregation can be suppressed. The addition of a stabilizer such as a surfactant, a base or an acid for enhancing the stability of the particles can be made unnecessary, or the addition amount thereof can be suppressed to the minimum. The dispersion diameter of the dispersed fine particles is preferably 1 μm or less when used as the base aggregated particles and when used as the additional fine particles. When the particle size is 1 μm or less, the particle size distribution of the finally produced toner is narrow, free fine particles are not generated, and the toner performance and reliability are improved.

The amount of the fine particle dispersion to be added depends on the volume fraction of the base aggregated particles contained, and the amount of the additional fine particles is preferably adjusted to be within 50% (volume conversion) of the finally generated aggregated particles. Within 50%, since the added fine particles adhere to the base aggregated particles without generating new aggregated particles, the composition distribution and particle size distribution are narrow, and the desired performance can be obtained.
In addition, the addition of the fine particle dispersion is divided and performed stepwise or gradually, which is effective in suppressing the generation of new fine aggregate particles and sharpening the particle size distribution and shape distribution. It is. Further, when the fine particle dispersion is added, it is released by heating at a temperature not higher than the glass transition temperature of the matrix aggregated particles and the resin of the additional fine particles, preferably in the range of 40 ° C. lower than the glass transition temperature to the glass transition temperature. The generation of fine particles can be suppressed.

  The thermoplastic binder resin used as the binder resin in the toner of the present invention includes styrenes such as styrene, parachlorostyrene, and α-methylstyrene; methyl acrylate, ethyl acrylate, n-propyl acrylate, lauryl acrylate, Esters having a vinyl group such as 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate; vinyl nitriles such as acrylonitrile and methacrylonitrile; vinyl Vinyl ethers such as methyl ether and vinyl isobutyl ether; vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and vinyl isopropenyl ketone; polyolefins such as ethylene, propylene and butadiene; Or a copolymer obtained by combining two or more of these, or a mixture thereof, and further, an epoxy resin, a polyester resin, a polyurethane resin, a polyamide resin, a cellulose resin, a polyether resin, a non-vinyl condensation resin, or these Examples thereof include a mixture with the vinyl resin, a graft polymer obtained by polymerizing a vinyl monomer in the presence of these, and the like. These resins may be used alone or in combination of two or more.

  Among these, when a vinyl monomer is used, a resin fine particle dispersion can be prepared by performing emulsion polymerization or seed polymerization using an ionic surfactant or the like. Dissolve the resin in a solvent with relatively low solubility in water, disperse the fine particles in water with a disperser such as a homogenizer in the presence of an ionic surfactant or polymer electrolyte in water, and then heat or reduce the pressure. A desired resin fine particle dispersion can be prepared by evaporating the solvent.

  The thermoplastic binder resin can stably produce fine particles obtained by emulsion polymerization or the like by blending a dissociable vinyl monomer. Examples of dissociative vinyl monomers include acrylic acid, methacrylic acid, maleic acid, cinnamic acid, fumaric acid, vinyl sulfonic acid, ethyleneimine, vinylpyridine, vinylamine and other polymer acids and polymer base materials. Any of the following monomers can be used, but a polymer acid is preferred because of the ease of polymer formation reaction, and further, acrylic acid, methacrylic acid, maleic acid, cinnamic acid, fumaric acid, etc. A dissociable vinyl monomer having a carboxyl group is particularly effective for controlling the degree of polymerization and the glass transition point.

  The volume average particle size of the resin fine particles is preferably 1 μm or less, and more preferably in the range of 0.01 to 1 μm. When the volume average particle size of the resin fine particles is 1 μm or less, the particle size distribution and shape distribution of the finally obtained electrostatic latent image developing toner are narrow, and the toner composition is not unevenly distributed due to the generation of free particles. It is preferable because it improves reliability. Further, when the volume average particle diameter of the resin particles is within the above range, the above disadvantages are eliminated, uneven distribution among the toners is reduced, dispersion in the toners is improved, and variations in performance and reliability are reduced. Is advantageous. The volume average particle diameter of the resin particles can be measured using, for example, a laser diffraction particle size distribution measuring machine.

  Examples of the release agent in the present invention include low molecular weight polyolefins such as polyethylene, polypropylene and polybutene; silicones having a softening point by heating; fatty acids such as oleic acid amide, erucic acid amide, ricinoleic acid amide and stearic acid amide Amides; plant waxes such as ester wax, carnauba wax, rice wax, candelilla wax, tree wax, jojoba oil, etc .; animal waxes such as beeswax; montan wax, ozokerite, ceresin, paraffin wax, microcrystalline Minerals such as waxes, Fischer-Tropsch waxes, petroleum-based waxes, and modified products thereof can be used. These waxes are dispersed in water together with ionic surfactants, polymer electrolytes such as polymer acids and polymer bases, and heated with a homogenizer or pressure discharge type disperser that can be heated above the melting point and impart strong shear. And a dispersion of particles of 1 μm or less can be prepared.

  The volume average particle size of the release agent particles is preferably 1 μm or less, more preferably 0.01 to 1 μm. When the volume average particle size is in the above range, the particle size distribution and shape distribution of the finally obtained electrostatic latent image developing toner are narrow, free particles are not generated, and toner composition is not unevenly distributed. It is preferable because it improves reliability. Further, when the volume average particle diameter of the resin particles is within the above range, the above disadvantages are eliminated, uneven distribution among the toners is reduced, dispersion in the toners is improved, and variations in performance and reliability are reduced. Is advantageous. In addition, the said volume average particle diameter can be measured using a laser diffraction type particle size distribution measuring machine etc.

  Examples of the colorant in the present invention include carbon black, chrome yellow, hansa yellow, benzidine yellow, sren yellow, quinoline yellow, permanent orange GTR, pyrazolone orange, vulcan orange, watch young red, permanent red, brillianthamine 3B, and brillianthamine 6B. , DuPont oil red, pyrazolone red, risor red, rhodamine B rake, lake red C, rose bengal, aniline blue, ultramarine blue, calco oil blue, methylene blue chloride, phthalocyanine blue, phthalocyanine green, malachite green oxalate Pigment or acridine, xanthene, azo, benzoquinone, azine, anthraquinone, thi Indico, dioxazine, thiazine, azomethine, indico, phthalocyanine, aniline black, polymethine, triphenylmethane, diphenylmethane, thiazole, etc. can do.

The content of the colorant in the toner of the present invention is preferably 1 to 20 parts by weight, more preferably 1 to 10 parts by weight with respect to 100 parts by weight of the binder resin. It is more preferable to set it as a weight part, and it is especially preferable that it is 2-7 weight part. As much as possible is preferable as long as the smoothness of the image surface after fixing is not impaired. It is also effective to use a surface-treated colorant or a pigment dispersant as necessary. By appropriately selecting the type of the colorant, yellow toner, magenta toner, cyan toner, black toner and the like can be obtained.
A magnetic material can be used as the black colorant. At this time, unlike other colorants, it is preferably added in the range of 30 to 70 parts by weight.

  The volume average particle diameter of the colorant particles in the present invention is preferably 0.8 μm or less, and more preferably in the range of 0.05 to 0.5 μm. When the volume average particle diameter of the colorant particles is 0.8 μm or less, the particle size distribution and shape distribution of the finally obtained electrostatic latent image developing toner are narrow, free particles are not generated, and the toner composition is unevenly distributed. This is preferable because it does not occur and leads to improvement in performance and reliability. Further, when the volume average particle diameter of the colorant particles is 0.05 μm or more, the colorability in the toner is improved, and the shape controllability that is one of the characteristics of the emulsion aggregation method is exhibited, so that the desired shape is obtained. This is preferable because it is possible to obtain a toner of

  In addition, a charge control agent can be used as necessary. Examples of the charge control agent include dyes composed of complexes of quaternary ammonium salts, nigrosine compounds, aluminum, iron, chromium, and triphenylmethane pigments. Various commonly used charge control agents can be used, but charge control agents that are difficult to dissolve in water due to the control of ionic strength that affects stability during aggregation and fusion integration and the reduction of wastewater contamination Is preferred.

  Surfactants used for emulsion polymerization, seed polymerization, colorant dispersion, resin particles, mold release agent dispersion, aggregation, or stabilization thereof are sulfate ester, sulfonate, phosphate ester, soap type. Anionic surfactant such as amine salt type, cationic surfactant such as quaternary ammonium salt type; nonionic surfactant such as polyethylene glycol type, alkylphenol ethylene oxide adduct type, polyhydric alcohol type; It is also effective to use together. As the dispersing means, a general dispersing machine such as a rotary shear type homogenizer, a ball mill having a media, a sand mill, or a dyno mill can be used.

  When using a composite comprising a resin and a colorant, the resin and the colorant are dissolved and dispersed in a solvent, then dispersed in water together with the appropriate dispersant, and then the solvent is removed by heating and decompression. Or a method of mechanically shearing or electrically adsorbing and immobilizing on a latex surface produced by emulsion polymerization or seed polymerization. These methods are effective in suppressing the liberation of the colorant as additional particles and improving the chargeable colorant dependency.

  Examples of the dispersion medium in the dispersion obtained by dispersing the resin fine particle dispersion, the colorant dispersion, the release agent dispersion, and the like include an aqueous medium. Examples of the aqueous medium include water such as distilled water and ion exchange water, and alcohols. These may be used individually by 1 type and may use 2 or more types together.

  In the present invention, a dispersion in which particles containing at least resin fine particles are dispersed is prepared by adding and mixing the resin fine particle dispersion, the colorant dispersion, the release agent dispersion, and the like. By heating in the range of the transition temperature, the resin particles, the colorant, and the release agent are aggregated to form aggregated particles. The number average particle diameter of the aggregated particles is preferably in the range of 3 to 10 μm.

  When the resin fine particle dispersion and the colorant dispersion are mixed, the content of the resin particles may be 40% by weight or less, and is preferably in the range of 2 to 20% by weight. . The content of the colorant may be 50% by weight or less, and is preferably in the range of 2 to 40% by weight. Furthermore, the content of the other components (particles) may be a level that does not hinder the object of the present invention, and is generally very small, specifically 0.01 to 5% by weight. The range is about 0.5 to 2% by weight.

  Next, after passing through the adhering step, if necessary, the mixed liquid containing aggregated particles is heat-treated at a temperature equal to or higher than the softening point of the resin, generally in the range of 70 to 120 ° C., and the aggregated particles are fused and colored. A particle-containing liquid can be obtained. The arithmetic average height of the toner can be controlled by the condition of the heat treatment. When the heat treatment temperature is increased, the surface of the toner becomes smooth and the arithmetic average height can be reduced. Conversely, by lowering the heat treatment temperature, the irregularities on the surface of the toner become large, and the arithmetic average height can be increased.

  The obtained colored particle dispersion is separated into toner particles by centrifugation or suction filtration, and washed 1 to 3 times with ion exchange water. Thereafter, the colored particles are separated by filtration, washed 1 to 3 times with ion exchange water, and dried to obtain the colored particles used in the present invention.

Next, the external additive used in the present invention will be described.
In the present invention, it is preferable to add an external additive for the purpose of charge control and transfer assistance. As external additives for the purpose of charge control, known materials can be used. Metal oxides such as titanium oxide, tin oxide, zirconium oxide, tungsten oxide, iron oxide, nitrides such as titanium nitride, silicon oxide, titanium compounds Etc. Depending on the purpose, the surface of these inorganic fine particles may be subjected to a known surface treatment. These inorganic compounds preferably have a number average particle size of 80 nm or less, and more preferably 50 nm or less. As the external additive for the purpose of assisting transfer, it is preferable to use an external additive having a median diameter of at least 0.1 μm and less than 0.3 μm. By using such an external additive, stress applied to the toner can be relieved and high transfer efficiency can be maintained. As the external additive having a median diameter of 0.1 μm or more and less than 0.3 μm, monodispersed spherical silica or monodispersed spherical organic resin fine particle external additives can be used.

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

  In the present invention, the adhesion state of the external additive to the colored particle surface may be merely mechanical adhesion or may be loosely fixed to the surface. Further, the entire surface of the colored particles may be coated or a part thereof may be coated. The addition amount of the external additive is preferably in the range of 0.3 to 3 parts by weight and more preferably in the range of 0.5 to 2 parts by weight with respect to 100 parts by weight of the colored particles. It is preferable for the amount added to be in the above-mentioned range since good toner fluidity can be obtained and blocking by heat storage can be sufficiently suppressed. Further, it is preferable because an excessive covering state does not occur and an excessive external additive is transferred to the contact member and does not cause a secondary failure. Moreover, it does not matter even if it goes through a sieving process after mixing external additives.

  The electrostatic latent image developing toner of the present invention can be suitably produced by the production methods as described above, but is not limited to these production methods.

<Carrier for electrostatic latent image developer>
The carrier of the present invention is characterized in that the median of the arithmetic average height distribution of the carrier is 0.20 μm or more and 0.40 μm or less. Here, the arithmetic average height Ra is a value obtained by extracting the reference length in the direction of the average line from the roughness curve of the carrier surface, and summing and averaging the absolute values of deviations from the average line of the extracted portion to the measurement curve. When the value is small, the surface is smooth. When the value is large, the surface is clear.
If the median of the arithmetic average height distribution of the carrier is less than 0.20 μm, the contact area with the toner cannot be ensured, so that the carrier and toner slip easily, toner scattering from the developing sleeve, and contamination inside the machine. Will occur. Further, if the median of the arithmetic average height distribution of the carrier is larger than 0.40 μm, the flowability of the developer is lowered and the magnetic brush on the developing sleeve becomes hard, so that the toner developed on the latent image carrier is Image defects and roughness caused by an image being disturbed by the two-component developer attached to the developing sleeve will occur.

The carrier of the present invention preferably has an arithmetic average height variation of 30 or less.
When the variation is 30 or less, there is no such a case that carriers with large surface irregularities and small carriers are mixed in the developer, and the state of dispersion of carriers with large surface irregularities and small carriers is not locally poor. It is preferable because a local decrease in developer fluidity does not occur. This is preferable because image defects and roughness due to such a local decrease in fluidity do not occur.

  The carrier of the present invention preferably has a cumulative 90% arithmetic average height distribution of less than 0.5 μm. It is preferable that the cumulative 90% value is less than 0.5 μm because carriers with extremely large surface irregularities are not mixed in the developer and the fluidity of the developer does not deteriorate. As a result, image defects and roughness due to a decrease in fluidity do not occur, which is preferable.

The arithmetic average height of the carrier was measured with an ultra-depth color 3D shape measuring microscope VK-9500 manufactured by Keyence Corporation. In this apparatus, a sample is irradiated with a laser to perform three-dimensional scanning. The laser reflected light at each position is monitored with a CCD camera to obtain three-dimensional surface information of the sample. The obtained surface information is statistically processed to obtain an index related to the surface roughness.
Here, 1,000 carriers were measured, data was statistically processed to determine the arithmetic average height distribution of the toner, and data such as the average value, median value, and standard deviation of the arithmetic average height were obtained. The fluctuation of the arithmetic average height referred to here is the percentage of the standard deviation with respect to the average value of the arithmetic average height.

  In the carrier of the present invention, it is preferable to form a coating layer on the surface of the core particle from the viewpoint of controlling the volume resistance of the carrier and preventing toner adhesion to the carrier surface. In the case of a carrier having such a configuration, the surface property (arithmetic average height) of the carrier can be controlled by the surface roughness of the core particle itself and the coating state of the coating layer.

  As a method for controlling the surface properties of the core particles, for example, in the case of ferrite powder, it can be obtained by appropriately selecting production conditions such as composition, calcination conditions, pulverization conditions, and sintering temperature. Specifically, the surface property can be smoothed by increasing the sintering temperature or extending the sintering time, and the surface irregularities are increased by increasing the sintering temperature or shortening the sintering time. Can be made. In particular, it is preferable to carry out with strict sintering temperature control.

The core particles that are the components of the carrier will be described.
Examples of the core particles include those in which magnetic powder is used alone as core particles, and those in which magnetic powder is finely divided and dispersed in a resin (magnetic fine particle-dispersed resin core particles). The magnetic powder is made into fine particles and dispersed in the resin by kneading and pulverizing the resin and magnetic powder, melting and spray-drying the resin and magnetic powder, and using a polymerization method to add the magnetic powder-containing resin in the solution. Examples include a polymerization method.
Examples of the magnetic material (magnetic powder) when magnetic powder is used alone for the core particles include magnetic metals such as iron, nickel and cobalt, and magnetic oxides such as ferrite and magnetite. The volume average particle diameter of the core particles is preferably 25 to 60 μm, more preferably 30 to 47 μm. It is preferable that the volume average particle size is in the above range because no carrier adheres to the image portion or the non-image portion, and image defects such as white spots in the image portion and black spots in the non-image portion occur. Furthermore, it is preferable because the graininess is excellent and no white spots or image formation occurs at the gradation boundary.

  As the core particles, all of the fine particles of ferromagnetic materials that are usually used can be used. Specific examples include triiron tetroxide, δ-iron sesquioxide, various ferrite powders, and magnetite granulated powders. . Among these, ferrite powder is preferable from the viewpoint of relatively low specific gravity and excellent transportability.

As magnetic characteristics of the core particle, the saturation magnetization at 3,000 oersted is preferably 50 A · m ² / kg (emu / g) or more, more preferably 55 to 90 A · m ² / kg (emu). / G). A saturation magnetization of 50 A · m ² / kg (emu / g) or more is preferable because the carrier is not developed and defects such as white spots do not occur.

  As a method for producing magnetic fine particle dispersed resin core particles, there is a method in which a monomer and magnetic fine particles are mixed and the monomer is polymerized to obtain carrier core particles. As the resin used for the polymerization, vinyl, epoxy, phenol, or the like is used. For example, as a method for producing a magnetic fine particle dispersed resin core particle using a phenol resin, a magnetic fine particle dispersed resin is prepared by adding and polymerizing a phenol and an aldehyde in an aqueous medium in the presence of a basic catalyst. Obtain core particles.

In the carrier of the present invention, the surface property can be controlled even when the coating layer is applied.
That is, when the surface property of the core particle is smooth, the surface property of the present invention can be obtained by adding fine particles having a large particle diameter to the resin to be coated and uniformly coating the surface of the composite film of the fine particles and the resin. Can do. In the case of a carrier having large surface irregularities, a carrier having a smooth surface property can be produced by increasing the amount of resin to be coated and filling the irregularities of the core particles with the resin.

The carrier coating layer of the present invention will be described.
Examples of the resin (matrix resin) for coating the magnetic particles include polyolefin resins such as polyethylene and polypropylene; and polyvinyl and polyvinylidene resins such as polystyrene, acrylic resin, polyacrylonitrile, polyvinyl acetate, polyvinyl butyral, and polyvinyl chloride. Polyvinyl carbazole; vinyl chloride-vinyl acetate copolymer; styrene-acrylic acid copolymer; silicone resin; fluorine-containing resin; fluororesin; polyester; polyurethane; In addition, a resin containing fluorine is preferably used in terms of carrier contamination. For example, fluoropolymers such as copolymers of vinylidene fluoride and acrylic monomers, copolymers of vinylidene fluoride and vinyl fluoride, terpolymers of tetrafluoroethylene, vinylidene fluoride and non-fluorinated monomers. And terpolymers.
Furthermore, what disperse | distributed electroconductive powder and crosslinked resin particles, such as carbon black, in fluorine-containing resin is preferable. By controlling the resistance value of the coating layer with a conductive powder such as carbon black, the carrier electric resistance value can be controlled, and by dispersing the carbon black and the crosslinked resin particles in the fluorine-containing resin, Resin can be reinforced and peeling of the resin coating layer can be suppressed. Moreover, the surface property of the carrier of the present invention can be achieved by selecting the size of the crosslinked resin particles corresponding to the surface property level of the magnetic particles. Furthermore, since basic carbon black and basic crosslinked resin particles are uniformly dispersed in the fluorine-containing resin, it is more preferable to use them.

The conductive powder preferably has a specific resistance of 10 ¹⁰ Ω · cm or less, and a volume average particle size of preferably 0.02 to 0.2 μm, more preferably 0.02 to 0. .1 μm. The conductive powder is preferably added in an amount of 1 to 25% by weight, more preferably 3 to 15% by weight in the coating layer. The conductive powder is used for the purpose of controlling the volume resistance of the carrier. However, if the addition amount is too large, the charge leakage may be large and the charge level may be too low. On the other hand, if the addition amount is too small, the volume resistance is There are cases where almost no effect is exhibited.

  The conductive powder is preferably present so as to be exposed on the surface of the carrier coating layer while having contact with the core particles coated with an insulating resin by a single conductive powder. As a result, most of the conductive powder can act as a conductive path in the coating layer.

  As the resin used for the coating layer (hereinafter referred to as coating resin), all general plastic resins can be used. Specifically, styrenes such as styrene, chlorostyrene, vinyl styrene; vinyl acetate, Vinyl esters such as vinyl propionate, vinyl benzoate, vinyl butyrate; methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, dodecyl (meth) acrylate, octyl (meth) acrylate Α-methylene aliphatic monocarboxylic acid esters such as phenyl (meth) acrylate; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl butyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropenyl ketone Homopolymers or copolymers such as And the like.

Typical examples of the coating resin include polystyrene, styrene / alkyl acrylate copolymer, styrene / alkyl methacrylate copolymer, styrene / acrylonitrile copolymer, styrene / butadiene copolymer, and styrene / maleic anhydride. Examples of the copolymer include polyester and polyurethane.
As the coating resin, polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin, waxes and the like can be used. Furthermore, a halogen-containing polymer can also be used, and specifically, a compound containing fluorine in the side chain is suitable, and fluorinated alkyl acrylate and fluorinated alkyl methacrylate are particularly exemplified as representative compounds.
As the coating resin, a fluorinated epoxy resin, a fluorinated polyester resin, a fluorinated silicon resin, or the like can also be used.
The said coating resin may be used individually by 1 type, and may be used together 2 or more types.

  Examples of the crosslinked fine particles used in the coating layer include benzoguanamine resin particles, melamine resin particles, and nitrogen-containing particles. The average primary particle size of these fine particles is preferably 0.1 to 1 μm, more preferably 0.2 to 0.8 μm. The addition amount of the crosslinked fine particles is preferably 1 to 50% by weight in the coating layer, and more preferably 5 to 20% by weight.

  The coating amount of the coating layer varies depending on the surface properties of the core particles, and the combination of the type and amount of conductive powder and crosslinked fine particles, but is generally 0.2 to 5.0% by weight based on the core particles. Preferably, it is 1.0 to 3.5% by weight. It is possible to control the surface property of the carrier by adjusting the coating amount.

  As a method for forming the coating layer, an immersion method in which the core particles are immersed in a coating layer forming solution containing the matrix resin, a conductive material, and a solvent, and a spray method in which the coating layer forming solution is sprayed on the surface of the core particles. There are a fluidized bed method in which the coating layer forming solution is sprayed in a state where the core particles are suspended by flowing air, and a kneader coater method in which the core particles and the coating layer forming solution are mixed in a kneader coater to remove the solvent.

  The solvent used in the coating layer forming solution is not particularly limited as long as it dissolves the matrix resin. For example, aromatic hydrocarbons such as toluene and xylene, and ketones such as acetone and methyl ethyl ketone. And ethers such as tetrahydrofuran and dioxane can be used. Further, the film thickness of the resin coating layer is usually in the range of 0.1 to 10 μm, but in the present invention, in order to develop a stable carrier volume resistivity over time, in the range of 0.5 to 5 μm. Preferably there is.

  As the electrostatic latent image developer of the present invention, the above-mentioned toner for developing an electrostatic latent image of the present invention is prepared by mixing in the range of 3 to 15 parts by weight with respect to 100 parts by weight of the carrier of the present invention. preferable.

(Image forming method)
The image forming method of the present invention comprises a step of forming an electrostatic latent image on an electrostatic latent image carrier, and developing the electrostatic latent image on the electrostatic latent image carrier with an electrostatic latent image developer containing toner. Forming a toner image, transferring the toner image onto a transfer member, and fixing the toner image. Each process itself is a general process, and is described in, for example, Japanese Patent Laid-Open Nos. 56-40868 and 49-91231. The image forming method of the present invention can be carried out using a known image forming apparatus such as a copying machine or a facsimile machine.

  The electrostatic latent image is formed by forming an electrostatic latent image on the electrostatic latent image carrier. The toner image is formed by developing the electrostatic latent image with a developer on the developer carrier. Is formed. In the transfer, a toner image is transferred onto a transfer target. Examples of the transfer target include a fixing substrate such as paper, an intermediate transfer roll, and an intermediate transfer belt. In the fixing, the toner image transferred onto the fixing substrate is fixed on the fixing substrate by heating from the fixing member.

  In the fixing, the toner image on the fixing base is heated and melted and fixed while the fixing base such as paper is passed between the two fixing members. The fixing member is in the form of a roll or a belt, and a heating device is attached to at least one of them. As the fixing member, a roll or a belt is used as it is, or its surface is coated with a resin.

The fixing roll is made by coating the core material surface with silicone rubber, viton rubber or the like.
For the fixing belt, polyamide, polyimide, polyethylene terephthalate, polybutylene terephthalate, or the like is used alone or in admixture of two or more. The roll and belt coating resins include, for example, styrenes such as styrene, parachlorostyrene, and α-methylstyrene, methyl acrylate, ethyl acrylate, n-propyl acrylate, lauryl acrylate, and 2-ethylhexyl acrylate. , Α-methylene fatty acid monocarboxylic acids such as methyl methacrylate, n-propyl methacrylate, lauryl methacrylate and 2-ethylhexyl methacrylate, nitrogen-containing acrylics such as dimethylaminoethyl methacrylate, vinyl nitriles such as acrylonitrile and methacrylonitrile Vinyl pyridines such as 2-vinyl pyridine and 4-vinyl pyridine, vinyl ethers such as vinyl methyl ether and vinyl isobutyl ether, vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl ketone and other vinyl ethers. Nyl ketones, olefins such as ethylene and propylene, homopolymers such as vinyl-based fluorine-containing monomers such as vinylidene fluoride, tetrafluoroethylene and hexafluoroethylene, or copolymers comprising two or more monomers, methyl silicone, Examples thereof include silicones such as methylphenyl silicone, polyesters containing bisphenol and glycol, epoxy resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, polycarbonate resins and the like. These resins may be used alone or in combination of two or more. Specific examples include homopolymers of fluorine-containing compounds such as polytetrafluoroethylene, vinylidene fluoride, and ethylene and / or copolymers thereof, homopolymers of unsaturated hydrocarbons such as ethylene and propylene, and / or Alternatively, a copolymer thereof can be used.

  As the fixing substrate for fixing the toner, paper, a resin film or the like is used. As the fixing paper, a coated paper in which a part or all of the paper surface is coated with a resin can be used. The fixing resin film can also be a resin-coated film whose surface is partially or entirely coated with another type of resin. In addition, it prevents friction between paper and resin film and / or double feeding of the fixing substrate caused by static electricity caused by friction, and the release agent elutes at the interface between the fixing substrate and the fixed image during fixing. Resin fine particles and inorganic fine particles may be added for the purpose of preventing deterioration of the adhesion of the fixed image.

  Specific examples of coating resins for paper and resin films include styrenes such as styrene, parachlorostyrene, and α-methylstyrene, methyl acrylate, ethyl acrylate, n-propyl acrylate, lauryl acrylate, 2-acrylic acid 2- Α-methylene fatty acid monocarboxylic acids such as ethylhexyl, methyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, nitrogen-containing acrylics such as dimethylaminoethyl methacrylate, vinyl such as acrylonitrile and methacrylonitrile Nitriles, vinyl pyridines such as 2-vinyl pyridine and 4-vinyl pyridine, vinyl ethers such as vinyl methyl ether and vinyl isobutyl ether, vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl ketone, etc. Homopolymers of vinyl ketones, olefins such as ethylene and propylene, vinylidene fluoride, tetrafluoroethylene, and vinyl-containing fluorine-containing monomers such as hexafluoroethylene, or copolymers composed of two or more monomers, methyl silicone, Examples thereof include silicones such as methylphenyl silicone, polyesters containing bisphenol and glycol, epoxy resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, polycarbonate resins and the like. These resins may be used alone or in combination of two or more.

  Specific examples of the inorganic fine particles include all particles that are usually used as external additives on the toner surface, such as silica, titania, calcium carbonate, magnesium carbonate, tricalcium phosphate, and cerium oxide. As the resin fine particles, for example, all particles usually used as an external additive on the toner surface such as vinyl resin, polyester resin, silicone resin, etc. can be used. These inorganic fine particles and organic fine particles can also be used as fluidity aids, cleaning aids, and the like.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

[Preparation of carrier]
(Manufacture of carrier A)
The finely pulverized product Mn-Mg-Sr ferrite particles A were put into a mechanomill, and the surface irregularities were mechanically reduced and classified to obtain ferrite classified core particles A.

Ferrite-classified core particles A 1,000 parts by weight Toluene 150 parts by weight Styrene methylmethacrylate vinylpyrrolidone copolymer 20 parts by weight (copolymerization ratio: 25/70/5, weight average molecular weight: 50,000)
・ Carbon black (volume average particle diameter 50 nm) 4 parts by weight ・ Melamine resin fine particles (volume average particle diameter 300 nm) 3 parts by weight In advance, the coating resin is dissolved in a solvent, and then carbon black and melamine resin fine particles are added to form glass beads. After mixing and dispersing in 2 mm and a roll mill for 30 minutes to remove the glass beads, the solvent is removed by drying under reduced pressure while stirring and mixing in the reduced pressure kneader together with the ferrite classified core particles A (the degree of vacuum at this time is substantially The degree of vacuum was controlled to -600 mmHg and the temperature during drying was controlled to 80 ° C. so that the drying time after drying was 10 minutes and the total tanning time after drying was 40 minutes. The resin-coated carrier A was obtained by sieving.
Table 1 shows the physical properties of the obtained carrier.

(Manufacture of carrier B)
The finely pulverized product B of Mn—Mg—Sr ferrite particles B was put into a mechanomill, and the surface irregularities were mechanically reduced and classified to obtain ferrite classified core particles B.

Ferrite-classified core particle B 2,000 parts by weight Toluene 300 parts by weight Styrene methylmethacrylate vinylpyrrolidone copolymer 30 parts by weight (copolymerization ratio: 25/70/5, weight average molecular weight: 100,000)
・ Carbon black (volume average particle diameter 50 nm) 5 parts by weight ・ Melamine resin fine particles (volume average particle diameter 300 nm) 4 parts by weight First, carbon black and melamine resin fine particles are added after dissolving the coating resin in a solvent, and glass beads After mixing and dispersing in 2 mm and a roll mill for 30 minutes to remove the glass beads, the solvent is removed by drying under reduced pressure while stirring and mixing in the reduced pressure kneader together with the ferrite classified core particles A (the degree of vacuum at this time is substantially The degree of vacuum was controlled to -600 mmHg and the temperature during drying was controlled to 80 ° C. so that the drying time after drying was 10 minutes and the total tanning time after drying was 40 minutes. The resin-coated carrier B was obtained by sieving. Table 2 shows the physical properties of the obtained carrier.

(Manufacture of carrier C)
Polyethylene (weight average molecular weight 9,0000, softening point 145 ° C.) 20 parts by weight Spherical magnetite (volume average particle size 1.0 μm) 80 parts by weight The above composition was melt-mixed while maintaining a high temperature of 170 ° C. with a heating attritor. Spray cooling was performed using a spray device having a disk-type nozzle, and classification was performed to obtain classified core particles C.

-Classification core particle C 2,000 parts by weight-300 parts by weight of toluene-45 parts by weight of styrene / methyl methacrylate / vinylpyrrolidone copolymer (copolymerization ratio: 25/70/5, weight average molecular weight: 200,000)
Carbon black (average particle size 50 nm) 3 parts by weight Melamine resin fine particles (average particle size 300 nm) 5 parts by weight After dissolving the coating resin in a solvent in advance, carbon black and melamine resin fine particles were added, and glass beads 2 mm After mixing and dispersing in a roll mill for 30 minutes and removing the glass beads, the solvent is removed by drying under reduced pressure while stirring and mixing in the reduced pressure kneader together with the classified core particles C (the degree of vacuum at this time is the actual drying time) The degree of vacuum is controlled to -600 mmHg and the temperature during drying is adjusted to 90 ° C. so that the tanning time after drying is 40 minutes and the total tanning time is 60 minutes after drying, and then sieved with a sieve having an opening of 75 μm. Thus, a resin-coated carrier C was obtained. Table 3 shows the physical properties of the obtained carrier.

(Manufacture of carrier D)
Mn-Mg-Sr ferrite finely pulverized product A 1,000 parts by weight Toluene 150 parts by weight Styrene methyl methacrylate vinylpyrrolidone copolymer 20 parts by weight (copolymerization ratio: 25/70/5, weight average molecular weight : 50,000)
・ Carbon black (average particle size 50 nm) 4 parts by weight ・ Melamine resin fine particles (volume average particle size 300 nm) 3 parts by weight First, carbon black and melamine resin fine particles are added after dissolving the coating resin in a solvent, and glass beads 2 mm And a roll mill for 30 minutes, after removing the glass beads, the solvent is removed by drying under reduced pressure with stirring and mixing in the reduced pressure kneader together with the finely pulverized ferrite particles A (the degree of vacuum at this time is substantially The degree of vacuum was controlled to -600 mmHg and the temperature during drying was controlled to 80 ° C. so that the drying time after drying was 10 minutes and the total tanning time after drying was 40 minutes. The resin-coated carrier D was obtained by sieving.
Table 4 shows the physical properties of the obtained carrier.

[Toner Preparation]
<Preparation of resin fine particle dispersion 1>
Styrene (manufactured by Wako Pure Chemical Industries, Ltd.) 310 parts by weight n-butyl acrylate (manufactured by Wako Pure Chemical Industries, Ltd.) 100 parts by weight β-carboxyethyl acrylate (manufactured by Rhodia Nikka Co., Ltd.) 9.0 parts by weight 1,10-decanediol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.) 1.5 parts by weight Dodecanethiol (manufactured by Wako Pure Chemical Industries, Ltd.) 3.0 parts by weight Disperse and emulsify 4 parts by weight of the surfactant Dow Fax (Dow Chemical Co.) in 550 parts by weight of ion-exchanged water in a flask, slowly stir and mix for 10 minutes, and then 6 parts by weight of ammonium persulfate. 50 parts by weight of ion-exchanged water in which was dissolved was added.
Next, after sufficiently replacing the nitrogen in the system, the flask was heated with an oil bath while stirring until the system reached 75 ° C., and emulsion polymerization was continued for 4 hours. As a result, an anionic resin fine particle dispersion 1 having a volume average diameter of 250 nm, a solid content of 41%, a glass transition point of 53 ° C., and an Mw of 33,000 was obtained.

<Preparation of resin fine particle dispersion 2>
Styrene (manufactured by Wako Pure Chemical Industries, Ltd.) 340 parts by weight n-butyl acrylate (manufactured by Wako Pure Chemical Industries, Ltd.) 60 parts by weight β-carboxyethyl acrylate (manufactured by Rhodia Nikka Co., Ltd.) 6.0 parts by weight 1, -10 decanediol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.) 2.5 parts by weight dodecanethiol (manufactured by Wako Pure Chemical Industries, Ltd.) 6.0 parts by weight Disperse and emulsify 4 parts by weight of the surfactant Dow Fax (Dow Chemical Co.) in 550 parts by weight of ion-exchanged water in a flask, slowly stir and mix for 10 minutes, and then 6 parts by weight of ammonium persulfate. 50 parts by weight of ion-exchanged water in which was dissolved was added.
Next, after sufficiently replacing the nitrogen in the system, the flask was heated with an oil bath while stirring until the system reached 75 ° C., and emulsion polymerization was continued for 4 hours. As a result, an anionic resin fine particle dispersion 2 having a volume average diameter of 200 nm, a solid content of 41%, a glass transition point of 65 ° C., and an Mw of 49,000 was obtained.

<Preparation of resin fine particle dispersion 3>
Styrene (manufactured by Wako Pure Chemical Industries, Ltd.) 290 parts by weight n-butyl acrylate (manufactured by Wako Pure Chemical Industries, Ltd.) 110 parts by weight β-carboxyethyl acrylate (manufactured by Rhodia Nikka Co., Ltd.) 6.0 parts by weight 1,10-decanediol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.) 1.5 parts by weight Dodecanethiol (manufactured by Wako Pure Chemical Industries, Ltd.) 6.0 parts by weight Disperse and emulsify 4 parts by weight of the surfactant Dow Fax (Dow Chemical Co.) in 550 parts by weight of ion-exchanged water in a flask, slowly stir and mix for 10 minutes, and then 6 parts by weight of ammonium persulfate. 50 parts by weight of ion-exchanged water in which was dissolved was added.
Next, after sufficiently replacing the nitrogen in the system, the flask was heated with an oil bath while stirring until the system reached 75 ° C., and emulsion polymerization was continued for 4 hours. As a result, an anionic resin fine particle dispersion 3 having a volume average diameter of 230 nm, a solid content of 41%, a glass transition point of 48 ° C., and an Mw of 30,000 was obtained.

<Preparation of Colorant Dispersion 1>
Carbon black (R330; manufactured by Cabot Corporation) 50 parts by weight Ionic surfactant Neogen RK (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 4 parts by weight Ion-exchanged water 200 parts by weight The above is mixed and dissolved, and a homogenizer (IKA Ultra Tarrax) ), And then irradiated with 28 KHz ultrasonic waves for 10 minutes using an ultrasonic disperser to obtain a colorant dispersion 1 having a volume average particle size of 150 nm and a solid content of 20%.

<Preparation of mold release agent dispersion 1>
50 parts by weight of paraffin Wax FNP0090 (melting point: 90.5 ° C, manufactured by Nippon Seiwa Co., Ltd.)
Ionic surfactant Neogen RK (Daiichi Kogyo Seiyaku Co., Ltd.) 1.5 parts by weight Ion-exchanged water 150 parts by weight The above was heated to 95 ° C. and sufficiently dispersed with IKA Ultra Turrax T50. Dispersion treatment was performed with a pressure-discharge type gorin homogenizer to obtain a release agent dispersion liquid 1 having a center diameter of 250 nm and a solid content of 25%.

<Manufacture of toner particles>
<Manufacture of toner particles 1>
Resin fine particle dispersion 1 200 parts by weight Colorant dispersion 1 30 parts by weight Release agent dispersion 1 36 parts by weight Polyaluminum chloride 0.08 part by weight Ion-exchanged water 350 parts by weight In a round stainless steel flask Thorough mixing and dispersion with Lux T50.
Next, 0.05 part by weight of polyaluminum chloride was added thereto, and the dispersion operation was continued with an ultra turrax. Thereafter, the flask was heated to 50 ° C. while stirring in an oil bath for heating, and held at 50 ° C. for 60 minutes.
Thereafter, the pH of the system was adjusted to 5.5 with a 0.5 mol / L sodium hydroxide aqueous solution, and then the stainless steel flask was sealed and heated to 95 ° C. while continuing to stir using a magnetic seal for 5 hours. Retained.
After completion of the reaction, the mixture was cooled, filtered, sufficiently washed with ion exchange water, and then subjected to solid-liquid separation by Nutsche suction filtration. This was further redispersed in 3 L of ion exchanged water at 40 ° C., and stirred and washed at 300 rpm for 15 minutes. This was repeated five more times, and when the pH of the filtrate reached 6.6 and the electric conductivity was 12 μS / cm, solid-liquid separation was performed using No5A filter paper by Nutsche suction filtration. Vacuum drying was then continued for 12 hours.

<Manufacture of toner particles 2>
Resin fine particle dispersion 3 140 parts by weight Colorant dispersion 1 30 parts by weight Release agent dispersion 1 36 parts by weight Polyaluminum chloride 0.08 parts by weight Ion-exchanged water 350 parts by weight In a round stainless steel flask Thorough mixing and dispersion with Lux T50.
Next, 0.05 part by weight of polyaluminum chloride was added thereto, and the dispersion operation was continued with an ultra turrax. The flask was then heated to 53 ° C. with stirring in a heating oil bath. After maintaining at 55 ° C. for 60 minutes, 60 parts by weight of the resin dispersion 3 was gradually added thereto.
Thereafter, the pH of the system was adjusted to 4.2 with a 0.5 mol / L sodium hydroxide aqueous solution, and then the stainless steel flask was sealed and heated to 97 ° C. while continuing to stir using a magnetic seal for 6 hours. Retained.
After completion of the reaction, the mixture was cooled, filtered, sufficiently washed with ion exchange water, and then subjected to solid-liquid separation by Nutsche suction filtration. This was further redispersed in 3 L of ion exchanged water at 40 ° C., and stirred and washed at 300 rpm for 15 minutes. This was repeated five more times, and when the pH of the filtrate reached 6.6 and the electric conductivity was 12 μS / cm, solid-liquid separation was performed using No5A filter paper by Nutsche suction filtration. Vacuum drying was then continued for 12 hours.

<Manufacture of toner particles 3>
Resin fine particle dispersion 3 120 parts by weight Colorant dispersion 1 30 parts by weight Release agent dispersion 1 36 parts by weight Polyaluminum chloride 0.08 part by weight Ion-exchanged water 350 parts by weight In a round stainless steel flask Thorough mixing and dispersion with Lux T50.
Next, 0.05 part by weight of polyaluminum chloride was added thereto, and the dispersion operation was continued with an ultra turrax. The flask was then heated to 53 ° C. with stirring in a heating oil bath. After maintaining at 53 ° C. for 60 minutes, 80 parts by weight of the resin dispersion 2 was gradually added thereto.
Thereafter, the pH of the system was adjusted to 4.2 with a 0.5 mol / L sodium hydroxide aqueous solution, and then the stainless steel flask was sealed and heated to 92 ° C. while continuing to stir using a magnetic seal for 12 hours. Retained.
After completion of the reaction, the mixture was cooled, filtered, sufficiently washed with ion exchange water, and then subjected to solid-liquid separation by Nutsche suction filtration. This was further redispersed in 3 L of ion exchanged water at 40 ° C., and stirred and washed at 300 rpm for 15 minutes. This was repeated five more times, and when the pH of the filtrate reached 6.6 and the electric conductivity was 12 μS / cm, solid-liquid separation was performed using No5A filter paper by Nutsche suction filtration. Vacuum drying was then continued for 12 hours.

<Manufacture of toner particles 4>
Resin fine particle dispersion 1 100 parts by weight Colorant dispersion 1 30 parts by weight Release agent dispersion 1 36 parts by weight Polyaluminum chloride 0.08 parts by weight Ion-exchanged water 350 parts by weight In a round stainless steel flask Thorough mixing and dispersion with Lux T50.
Next, 0.05 part by weight of polyaluminum chloride was added thereto, and the dispersion operation was continued with an ultra turrax. Thereafter, the flask was heated to 50 ° C. with stirring in a heating oil bath. After holding at 50 ° C. for 60 minutes, 100 parts by weight of the resin dispersion 2 was gently added thereto.
Thereafter, the pH of the system was adjusted to 6.0 with a 0.5 mol / L sodium hydroxide aqueous solution, and then the stainless steel flask was sealed, heated to 95 ° C. with stirring using a magnetic seal, and held for 6 hours. did.
After completion of the reaction, the mixture was cooled, filtered, sufficiently washed with ion exchange water, and then subjected to solid-liquid separation by Nutsche suction filtration. This was further redispersed in 3 L of ion exchanged water at 40 ° C., and stirred and washed at 300 rpm for 15 minutes. This was repeated five more times, and when the pH of the filtrate reached 6.6 and the electric conductivity was 12 μS / cm, solid-liquid separation was performed using No5A filter paper by Nutsche suction filtration. Vacuum drying was then continued for 12 hours.

<Preparation of external additive particles 1>
TiO (OH) ₂ in the manufacture, using ilmenite as ore, to separate the soluble part friendly dissolved in sulfuric acid and using a wet precipitation method to produce a TiO (OH) ₂ was hydrolyzed TiOSO _4.
In the process, dispersion preparation and washing with water for hydrolysis and nucleation were performed. To 100 parts by weight of TiO (OH) ₂ dispersed in 1,000 ml of water prepared by this method, 40 parts by weight of isobutyltrimethoxysilane was added dropwise with stirring at room temperature. This was then filtered, washed repeatedly with water, and the resulting titanium compound was dried at 150 ° C. to obtain external additive particles 1 having a volume average particle size of 35 nm and a BET (BET specific surface area) of 100 m ² / g.

<Preparation of Toner 1, 2, 3, 4>
To 100 parts by weight of the obtained toner particles 1, 2, 3 and 4, 0.8 parts by weight of external additive particles 1 and hexamethyldisilazane-treated silica having an average particle diameter of 50 nm were added, and 5 L Mix with a modified sill mixer (base made by Mitsui Miike Processing Co., Ltd.) at a peripheral speed of 45 m / s for 10 minutes, and then sieve with an ultrasonic sieving machine with a mesh opening of 45 μm. 4 was obtained. The physical properties of the toner are summarized in Table 5.

<Production of developer>
<Example 1>
With respect to 8 parts by weight of the toner 1 obtained above, 92 parts by weight of the carrier A obtained above was mixed with a V-type blender to obtain a developer 1.

<Example 2>
With respect to 8 parts by weight of the toner 1 obtained above, 92 parts by weight of the carrier B obtained above was mixed with a V-type blender to obtain a developer 2.

<Example 3>
With respect to 8 parts by weight of the toner 1 obtained above, 92 parts by weight of the carrier C obtained above was mixed with a V-type blender to obtain a developer 3.

<Comparative Example 1>
To 8 parts by weight of the toner 2 obtained above, 92 parts by weight of the carrier D obtained above was mixed with a V-type blender to obtain a developer 4.

<Comparative example 2>
To 8 parts by weight of the toner 1 obtained above, 92 parts by weight of the carrier D obtained above was mixed with a V-type blender to obtain a developer 5.

<Comparative Example 3>
To 8 parts by weight of the toner 2 obtained above, 92 parts by weight of the carrier A obtained above was mixed with a V-type blender to obtain a developer 6.

<Comparative example 4>
To 8 parts by weight of the toner 3 obtained above, 92 parts by weight of the carrier A obtained above was mixed with a V-type blender to obtain a developer 7.

<Comparative Example 5>
To 8 parts by weight of the toner 4 obtained above, 92 parts by weight of the carrier A obtained above was mixed with a V-type blender to obtain a developer 8.

(Image formation test)
The obtained developer was applied to DocuCenterColor500 manufactured by Fuji Xerox Co., Ltd. and set to an environmental temperature of 20 ° C. and a humidity of 50% RH, and 50,000 single-color image formation tests were performed. Evaluation was performed.
The image forming method includes a step of forming an electrostatic latent image on the electrostatic latent image carrier, and the electrostatic latent image on the electrostatic latent image carrier using an electrostatic latent image developer containing toner. It includes a step of developing and forming a toner image, a step of transferring the toner image, and a step of fixing the toner image. The image forming method further includes a cleaning step.

<Single color image formation test>
The developer was housed in the developing machine of the image forming apparatus, and the development conditions were set so that the toner development amount on the photoreceptor was 50 to 60 g / m ² . In this state, it was left for 72 hours in an environment of temperature 20 ° C. and humidity 50% RH.

<Evaluation of image loss / Gastsuki>
Regarding image loss / grayness, it was determined by visual evaluation that ◎ indicates no problem, ○ indicates that it is generated but within an allowable level, Δ indicates that it is generated but the allowable level lower limit, and × indicates a level that can be recognized as an image quality failure.

<Contamination assessment inside machine>
The amount of free toner during the image forming test of 50,000 sheets was measured using a dust track Model 3451 manufactured by Nippon Kanomax Co., Ltd. The measurement was performed by inserting a Freon tube air inlet into the DocuCentreColor 500, fixing the air inlet to a position about 10 mm from the developer carrier, sucking free toner near the developer carrier into the dust track Model 3451, and measuring the amount of free toner. . The dust track Model 3451 was set at an air flow rate of 1.7 L / min and a 10 μm inlet nozzle was used.
Evaluation was based on the average amount of free toner during the formation of 50,000 images.
2.0 mg / s / m ³ or less ◎
2.1-4.9 mg / s / m ³
4.9-9.9 mg / s / m ³ △
10.0 mg / s / m ³ or more
The evaluation results are shown in Table 6.

As can be seen from Table 6, Examples 1 to 3 of the present invention can prevent image defects, image roughness, and contamination inside the machine. Further, in Example 2, since the variation of the carrier arithmetic average is controlled in addition to the average circularity / arithmetic average cumulative 90% value of the toner and the carrier arithmetic average median value, the level of roughness is improved. Further, in Example 3, since the average circularity / arithmetic average cumulative 90% value of the toner and the carrier arithmetic average median / arithmetic average fluctuation are controlled, the carrier arithmetic average cumulative 90% value is also controlled. The amount of toner is reduced, and the contamination inside the machine is good.
On the other hand, Comparative Example 1 in which the toner / carrier does not satisfy the constituent requirements of the present invention, Comparative Example 2 in which the constituent requirements of the carrier are not satisfied, and Comparative Examples 3, 4, and 5 in which the constituent requirements of the toner are not satisfied are all free toner. It can be seen that the amount / gassiness level is bad.

Claims (6)

An electrostatic latent image developer comprising an electrostatic latent image developing toner and a carrier,
The electrostatic latent image developing toner has colored particles containing at least a binder resin, a colorant, and a release agent, and an external additive.
The average circularity of the toner is 0.940 or more and less than 0.970,
The cumulative 90% value of the arithmetic average height distribution of the toner is 0.15 μm or more,
The median arithmetic average height of the toner is 0.08 μm or more and 0.15 μm or less;
The electrostatic latent image developer, wherein the median of the arithmetic average height distribution of the carrier is 0.20 μm or more and 0.40 μm or less.   The electrostatic latent image developer according to claim 1, wherein the arithmetic average height variation of the toner is 35% or more and 60% or less.   The electrostatic latent image developer according to claim 1, wherein the number average particle diameter of the toner is 5.0 μm or more and 7.0 μm or less.   The electrostatic latent image developer according to any one of claims 1 to 3, wherein the variation in the arithmetic average height of the carrier is 30 or less.   The electrostatic latent image developer according to claim 1, wherein the 90% cumulative value of the arithmetic average height distribution of the carrier is less than 0.5 μm. Forming an electrostatic latent image on the electrostatic latent image carrier;
Developing the electrostatic latent image on the electrostatic latent image carrier with an electrostatic latent image developer containing toner to form a toner image;
Transferring the toner image;
A step of fixing the toner image, and an image forming method comprising:
An image forming method comprising using the electrostatic latent image developer according to any one of claims 1 to 5 as the developer.