JP2016161791A - Toner for electrostatic latent image development and two-component developer for electrostatic latent image development - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner for electrostatic latent image development that has a small diameter and high circularity and can achieve both fluidity and a cleaning property.SOLUTION: A toner for electrostatic latent image development of the present invention includes toner base particles and an external additive adhered to the surface of each of the toner base particles, the toner for electrostatic latent image containing toner particles having a median size of a volume reference within a range of 3 to 7 μm and an average circularity of 0.945 to 1.00, and containing, as the external additive, silica particles having a median size of a number reference within a range of 70 to 160 nm and manufactured by a sol-gel method, where the peak-top particle size in a particle size distribution of the silica particles that are subjected to ultrasonic dispersion treatment in water to be isolated satisfies the formula (1).SELECTED DRAWING: Figure 2

Description

  The present invention relates to an electrostatic latent image developing toner and an electrostatic latent image developing two-component developer. In particular, the present invention relates to a toner for developing an electrostatic latent image having a small diameter and a high circularity and having both fluidity and cleaning properties, and a two-component developer for developing an electrostatic latent image containing the toner.

In recent years, electrophotographic copying machines and printers have been used not only in the conventional office area but also in the production print market due to the increased printing speed.
In the production print market, high-definition and high-quality image quality equivalent to offset printing is required. For this reason, the toner and carrier used therein tend to have a smaller particle size.

  However, there is a problem that the fluidity and the cleaning property are deteriorated in the toner having a reduced diameter.

Here, as shown in FIG. 1, as a method for cleaning the toner particles 201 attached to the member to be cleaned 101 such as a photoconductor or an intermediate belt, the toner particles 201 are brought into contact with the member to be cleaned 101 by contacting the cleaning blade 102. The method of scraping off is mentioned.
In the above-described toner particles having a reduced diameter, it is preferable to increase the degree of circularity in order to improve the fluidity. However, the toner particles 201 having an increased degree of circularity are easy to roll and move from the cleaning blade 102 in the arrow direction a. It becomes easy to slip through. Further, aggregates of the toner particles 201 are generated in the nip portion 103 between the member to be cleaned 101 and the cleaning blade 102, and the aggregates of the toner particles 201 are more than the force b at which the cleaning blade 102 contacts the member to be cleaned 101. The force c that enters the portion 103 becomes larger. Due to these phenomena, it is conceivable that the cleaning property deteriorates with small-diameter toner particles having a high circularity.

In order to ensure the cleaning property of the toner, as shown in FIG. 1, the stationary layer 203 is formed by closely packing the external additive 202 detached from the toner particles 201 in the nip portion 103, and the stationary layer 203. Is used to dampen and scrape off the toner particles 201. In such a method, the adhesion between the toner particles 201 and the surface of the member to be cleaned 101 is reduced by applying a large-diameter external additive 202 to the surface of the toner particles 201 to obtain a spacer effect. In general, the static layer 203 is effectively formed.
In addition, since a large-diameter external additive is easily detached from toner particles, a technique using an irregular-shaped large-diameter external additive has been proposed in order to improve the adhesion strength (see, for example, Patent Document 1).

  Here, as a means for achieving both the fluidity and the spacer effect, a technique using an external additive having a wide particle size distribution has been proposed (see, for example, Patent Document 2). In addition, the technique using an external additive having a wide particle size distribution is excellent in the close-packing property with respect to the formation of a static layer, and therefore, the aggregation state is not easily lost, and the static layer is formed at the nip portion between the blade and the photoconductor. (See, for example, Patent Document 3).

  However, it is conceivable that those having a wide particle size distribution and easy to close packing form agglomerates with the cleaning blade, and the agglomerates slip through the blade and wear the photoreceptor. In addition, when the static layer collapses, the surrounding external additives are difficult to rearrange, and the durability stability is deteriorated.

JP 2013-53027 A JP 2004-102236 A JP 2007-264142 A

  The present invention has been made in view of the above problems and circumstances, and a solution to the problem is a toner for developing an electrostatic latent image having a small diameter and a high circularity, and having both fluidity and cleaning properties. It is to provide a two-component developer for developing an electrostatic latent image.

As a result of investigating the cause of the above-mentioned problems in order to solve the above-mentioned problems according to the present invention, silica particles prepared by a sol-gel method having a median diameter on the number basis in the range of 70 to 160 nm as an external additive And an external additive that forms a stationary layer by being released from the toner when the particle size distribution of the silica particles released by ultrasonic dispersion treatment in water satisfies the following formula (1): It has been found that there are those having different particle diameters, and the fluidity and the cleaning property can be compatible by suppressing the clogging of the external additive.
That is, the subject concerning this invention is solved by the following means.

1. A toner base particle and an external additive attached to the surface of the toner base particle; a volume-based median diameter in the range of 3 to 7 μm; and an average circularity in the range of 0.945 to 1.00 An electrostatic latent image developing toner containing toner particles,
As the external additive, containing silica particles prepared by a sol-gel method in which the median diameter on the number basis is in the range of 70 to 160 nm,
A toner for developing an electrostatic latent image, wherein the particle size distribution of the silica particles liberated by ultrasonic dispersion treatment in water satisfies the following formula (1).
Equation _{(1): 1.1 ≦ S 1} / S 3 ≦ 2.8
(In Formula (1), S ₁ represents the particle size of the peak top in the particle size distribution of the silica particles released in 1 minute of ultrasonic dispersion treatment, and S ₃ represents the silica released in 3 minutes of ultrasonic dispersion treatment. (This represents the peak top particle size in the particle size distribution.)

  2. 2. The electrostatic latent image developing toner according to item 1, wherein the silica particles contain silica particles prepared by two kinds of sol-gel methods having different median diameters based on the number.

  3. A two-component developer for developing an electrostatic latent image, comprising the toner for developing an electrostatic latent image according to item 1 or 2, and a carrier.

According to the present invention, there are provided a toner for developing an electrostatic latent image having a small diameter and a high circularity and having both fluidity and cleaning properties, and a two-component developer for developing an electrostatic latent image containing the toner. Can do.
The expression mechanism or action mechanism of the effect of the present invention is not clear, but is presumed as follows.
By increasing the circularity of the small-diameter toner, the fluidity of the toner particles can be improved, the adhesion strength between the toner base particles and the external additive is reduced, and a free external additive that forms a stationary layer at the nip portion of the cleaning blade The agent can be easily generated. However, the toner having a high degree of circularity is easy to roll, so that it easily slips out from the nip portion between the cleaning blade and the member to be cleaned, or aggregates are formed in the nip portion and the cleaning blade comes into contact with the photosensitive member or the like. It is also conceivable that the cleaning property is deteriorated by the fact that the force with which the aggregate enters the nip portion becomes larger than the force. In order to suppress them, the structure of the static layer formed by the external additive is important, and the present invention focuses on the particle size distribution of the external additive that forms the static layer.
In the formation of the static layer, it is preferably composed of a large-sized external additive having a particle diameter of 70 to 160 nm released from the toner, and a small-sized external additive having a particle diameter of less than 70 nm slips out of the cleaning blade and exceeds 160 nm. A large-diameter external additive is advantageous for cleaning properties, but is not preferable because the fluidity of the toner decreases.
As in the present invention, it is preferable that the particle size of the free external additive is not uniform and has a particle size distribution in order to achieve both fluidity and cleaning properties. When the particle size of the free external additive is uniform, it tends to be densely clogged, and aggregates of the external additive are generated at the nip portion of the cleaning blade, causing slipping from the cleaning blade and photoconductor wear. On the other hand, when the free external additive has a particle size distribution as in the present invention, voids are formed between the particles, so that it is difficult to close the particles and form aggregates. Moreover, the external additive which forms a static layer is easy to fluidize by having an appropriate space | gap, and when a static layer collapse | crumbles, the external additive particle | grains of the circumference | surroundings fluidize easily and are excellent also in durability stability. Further, it is considered that an external additive having a particle size distribution is easily fluidized because appropriate voids are formed between toner particles even in a toner state.
Further, as the external additive, it is preferable to form a stationary layer with silica particles because the influence on the fluctuation of the charge amount when released from the toner is small.
S ₁ / S ₃ in the above formula (1) indicates the particle size distribution of the external additive that is released from the toner base particles to form a static layer, and is subjected to ultrasonic dispersion treatment in water under the conditions of the present invention. By carrying out, a large external additive having a diameter of 70 to 160 nm, which is particularly effective for cleaning properties, is mainly released. Therefore, by measuring the value of S ₁ / S ₃ , it is possible to know the distribution of the external additive that is separated from the toner base particles and collected on the cleaning blade and forms a stationary layer. If it is smaller than 1.1, the particle size of the free external additive is uniform, so that it is likely to be densely clogged when the stationary layer is formed, and the photoreceptor is worn and the cleaning property is deteriorated. On the other hand, when the ratio is larger than 2.8, the external additive enters into the gaps between the particles of the external additive and clogs more closely, so that the above effect cannot be obtained. In addition, even when the external additive has a wide particle size distribution, the above effects cannot be obtained because the external additive tends to be densely packed.

Schematic diagram explaining an example of cleaning Schematic diagram showing an example of the configuration of toner particles according to the present invention

The toner for developing an electrostatic latent image of the present invention includes toner base particles and an external additive attached to the surface of the toner base particles, and has a median diameter in a range of 3 to 7 μm on a volume basis, and an average circular shape. An electrostatic latent image developing toner containing toner particles having a degree of 0.945 to 1.00, wherein the external additive has a median diameter on the number basis of 70 to 160 nm. It contains silica particles prepared by a sol-gel method and is characterized in that the particle size of the peak top in the particle size distribution of the silica particles liberated by ultrasonic dispersion treatment in water satisfies the formula (1). This feature is a technical feature common to or corresponding to each of claims 1 to 3.
In the present invention, the silica particles preferably contain silica particles prepared by two kinds of sol-gel methods having different median diameters based on the number. Thereby, the particle size distribution can be given to the external additive, and the voids between the particles of the external additive can be appropriately maintained, so that the stationary layer is more easily fluidized and preferable for obtaining the above effect of the present invention. .

  Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In addition, in this application, "-" is used in the meaning which includes the numerical value described before and behind that as a lower limit and an upper limit.

<Overview of toner for electrostatic latent image development>
The electrostatic latent image developing toner of the present invention (hereinafter also simply referred to as “toner”) includes toner base particles and an external additive attached to the surface of the toner base particles, and has a median diameter on a volume basis. An electrostatic latent image developing toner containing toner particles having a range of 3 to 7 μm and an average circularity in a range of 0.945 to 1.00. The particle size distribution of the silica particles containing silica particles prepared by a sol-gel method having a median diameter in the range of 70 to 160 nm and freed by ultrasonic dispersion in water is expressed by the following formula: (1) is satisfied.

[Toner particles]
The toner particles according to the present invention include at least toner base particles and an external additive.
FIG. 2 shows an example of the configuration of the toner particles according to the present invention. In the example shown in FIG. 2, silica particles A and B, which are external additives that are released when subjected to ultrasonic dispersion treatment in water and are prepared by a sol-gel method having different peak tops in the particle size distribution, The toner particles 300 are formed by adhering to the particles 301.

(Median diameter and average circularity of toner particles based on volume)
The toner particles constituting the toner of the present invention have a volume-based median diameter in the range of 3 to 7 μm.

  When the volume-based median diameter is in the above range, the transfer efficiency is increased, the image quality of halftone is improved, and the image quality of fine lines and dots is improved.

  The volume-based median diameter of the toner particles is measured and calculated using a measuring apparatus in which a data processing computer system (Beckman Coulter) is connected to “Multisizer 3” (Beckman Coulter, Inc.).

  Specifically, 0.02 g of toner is added to 20 ml of a surfactant solution (for example, a surfactant solution obtained by diluting a neutral detergent containing a surfactant component 10 times with pure water for the purpose of dispersing toner particles). Then, it was dispersed with an ultrasonic wave for 1 minute to prepare a dispersion of toner particles, and this toner particle dispersion was prepared in a beaker containing “ISOTON II” (manufactured by Beckman Coulter) in a sample stand. Then, inject with a pipette until the display concentration of the measuring device is 5 to 10%. Here, a reproducible measurement value can be obtained by setting the concentration range. In the measuring apparatus, the measurement particle count is 25000, the aperture diameter is 50 μm, the frequency value is calculated by dividing the measurement range of 1 to 30 μm into 256, and the volume integrated fraction is 50 % Is the volume-based median diameter.

The average circularity of the toner particles constituting the toner of the present invention is in the range of 0.945 to 1.00.
The average circularity can be measured using “FPIA-2100” (manufactured by Sysmex) (4000 HPF detection numbers).

[External additive]
The external additive according to the present invention contains silica particles prepared by a sol-gel method having a median diameter in the range of 70 to 160 nm on a number basis, and is free of silica particles that are released by ultrasonic dispersion treatment in water. The particle size of the peak top in the particle size distribution satisfies the following formula (1).
Equation _{(1): 1.1 ≦ S 1} / S 3 ≦ 2.8
In the above formula (1), S ₁ represents the peak top particle size in the particle size distribution of silica particles released in 1 minute of ultrasonic dispersion treatment, and S ₃ represents the silica particles released in 3 minutes of ultrasonic dispersion treatment. It represents the particle size of the peak top in the particle size distribution.

In the present invention, an ultrasonic dispersion treatment in water, as well as the measurement of S ₁ and S ₃ in the formula (1) may be given in the following steps.
In a 50 mL screw tube bottle, 3 g of toner is wetted with 40 g of a 0.2% aqueous solution of polyoxyethyl phenyl ether and stirred well. Then, it transfers to a 60 mL disposable cup, and it adjusts so that chip | tip (phi) 36 of an ultrasonic transducer may be immersed in a solution about 3 cm in ultrasonic type homogenizer OS-1200. Thereafter, the ultrasonic energy is adjusted to 100 W, and ultrasonic waves are applied for 1 minute and 3 minutes, respectively. Each dispersion is transferred to a 15 ml test tube and centrifuged at 3000 rpm for 10 minutes in a centrifuge CN-1040 and the supernatant is recovered. The collected supernatant is dispersed by applying ultrasonic waves for 3 minutes at an output of 80 W with an ultrasonic cleaner US-1, and then the particle size distribution is measured with a dynamic light scattering nanotrack particle size analyzer UPA-150. . At this time, as measurement conditions, the refractive index of the particles is 1.51 and the specific gravity is 2.0. Among the particle size distributions obtained for the ultrasonic dispersion treatment for 1 minute and 3 minutes, the peak top particle sizes in the range of 50 to 190 nm are denoted by S ₁ and S ₃ , respectively.

The above formula (1) can be satisfied, for example, when the silica particles contained as an external additive contain silica particles prepared by two kinds of sol-gel methods having different median diameters based on the number. The silica particles prepared by the sol-gel method having different median diameters on the number basis indicate silica particles having a median diameter on the number basis different by 20 nm or more.
Thereby, the particle size distribution can be given to the external additive, and the gaps between the particles of the external additive can be appropriately maintained. Therefore, the external additive is hardly clogged and is difficult to form an aggregate. Moreover, the external additive which forms a static layer is easy to fluidize by having a moderate space | gap, and when a static layer collapses, the external additive of the circumference | surroundings fluidizes and is easy to arrange | position and is excellent also in durability stability. Thus, it is preferable to use two types of silica particles having different median diameters on the basis of the number in terms of obtaining the above effect of the present invention.

In the present invention, the median diameter based on the number of external additives is measured by the following method.
Using a scanning electron microscope (SEM) “JEM-7401F” (manufactured by JEOL Ltd.), an SEM photograph of the toner magnified 30,000 times is taken, and the SEM photograph is observed to form primary particles of silica particles. The diameter (Ferret diameter) is measured, and the total value is divided by the number to determine the average particle diameter. The particle size is measured by selecting a region where the total number of particles is about 100 to 200 in the SEM image.

(Method for preparing silica particles by the sol-gel method)
A method for preparing silica particles by the sol-gel method will be described. Silica particles prepared by the sol-gel method are nearly spherical in shape compared to general fumed silica, have a relatively large particle size and uniform particle size distribution, and are easily dispersed as primary particles on the toner surface. . Therefore, it is easy to control the particle size distribution of the external additive particles forming the stationary layer.
For the silica particles according to the present invention, a known silica particle production method can be used. In this case, the silica particles according to the present invention are mainly produced through three steps of hydrolysis, polycondensation, and hydrophobization treatment. Accordingly, other steps such as drying may be combined.

  Next, the outline of the production process of the silica particles according to the present invention by the sol-gel method will be described below. First, alkoxysilane is dropped and stirred while adding a catalyst and applying temperature in the presence of water and alcohol. Next, the silica sol suspension obtained by the reaction is centrifuged to separate into wet silica gel, alcohol and aqueous ammonia. A solvent is added to wet silica gel to form a silica sol again, and a hydrophobizing agent is added to hydrophobize the silica surface. Alternatively, after the sol is dried to obtain a dry sol, a hydrophobizing agent is added, and the silica surface is hydrophobized.

  As the hydrophobizing agent, a general coupling agent, silicone oil, fatty acid, fatty acid metal salt, or the like can be used. Next, the silica particles according to the present invention can be obtained by removing the solvent from the hydrophobized silica sol and drying it. Further, the silica particles thus obtained may be subjected to a hydrophobic treatment again.

  For example, a dry method such as a spray drying method in which a treatment agent or a solution containing a treatment agent is sprayed on particles suspended in a gas phase, or a wet method in which particles are immersed in a solution containing a treatment agent and dried. Alternatively, a step of processing by a mixing method in which a processing agent and particles are mixed by a mixer may be added.

As the silane compound used as the hydrophobizing agent, a water-soluble compound can be used. As such a silane compound, those represented by the following structural formula (i) can be used.
Structural formula (i): R _a SiX _4-a
Here, in the structural formula (i), a is an integer of 0 to 3, R represents an organic group such as a hydrogen atom, an alkyl group, or an alkenyl group, and X represents a hydrous such as a chlorine atom, a methoxy group, or an ethoxy group. Represents a degradable group.

  Examples of the compound represented by the structural formula (i) include chlorosilane, alkoxysilane, silazane, and a special silylating agent. Specifically, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, tetraethoxysilane, Methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, isobutyltrimethoxysilane, decyltrimethoxysilane, hexamethyldisilazane, N, O- (bistrimethylsilyl) acetamide, N, N-bis (Trimethylsilyl) urea, tert-butyldimethylchlorosilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxy Silane, γ-methacryloxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-mercapto Representative examples include propyltrimethoxysilane and γ-chloropropyltrimethoxysilane.

Particularly preferably, the hydrophobizing agent used in the present invention includes dimethyldimethoxysilane, hexamethyldisilazane (HMDS), methyltrimethoxysilane, isobutyltrimethoxysilane, decyltrimethoxysilane and the like.
Specific examples of silicone oils include, for example, cyclic compounds such as organosiloxane oligomers, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, tetramethylcyclotetrasiloxane, tetravinyltetramethylcyclotetrasiloxane, linear or Mention may be made of branched organosiloxanes. Further, a highly reactive silicone oil in which a modifying group is introduced into a side chain or one end or both ends, a side chain piece end, or both side chain ends may be used. Examples of the modifying group include, but are not particularly limited to, alkoxy, carboxyl, carbinol, higher fatty acid modification, phenol, epoxy, methacryl, amino and the like. Further, for example, it may be a silicone oil having several kinds of modifying groups such as amino / alkoxy modification. Further, dimethyl silicone oil, these modified silicone oils, and other surface treatment agents may be mixed or combined. Examples of the treating agent used in combination include silane coupling agents, titanate coupling agents, aluminate coupling agents, various silicone oils, fatty acids, fatty acid metal salts, esterified products thereof, rosin acid, and the like. .

(Measurement of volume average primary particle size of silica particles)
The volume average primary particle size of the silica particles can be measured using “Laser diffraction / scattering particle size distribution analyzer LA-750” (manufactured by Horiba, Ltd.) as follows.
After adding silica particles to methanol so that the mass ratio is 1: 0.005, the silica particles are dispersed in methanol by an ultrasonic irradiator. By measuring the particle size distribution of the silica particles thus treated with “Laser diffraction / scattering particle size distribution analyzer LA-750” (manufactured by Horiba, Ltd.), the volume average primary particle size can be determined.
The volume average primary particle size thus determined is the volume average particle size of the silica particles according to the present invention.
In addition, the average particle diameter of the silica particles was measured using an electron microscope, and compared with the volume average particle diameter obtained from the measurement result by the apparatus, it was confirmed that those values were consistent with each other. By confirming that the silica particles are not aggregated, it can be determined that the volume average particle size is that of the primary particles. The standard deviation of the volume average particle diameter can be determined simultaneously with the volume average particle diameter when measuring “LA-750”.

(Addition amount of silica particles)
The addition amount of the silica particles of the present invention is preferably 0.7 to 3.0% by mass with respect to the toner base particles. That is, when the content is 0.7% by mass or more, a sufficient development / transfer improving effect is obtained, and when the content is 3.0% by mass or less, the adhesion between the toner particles and the photosensitive member, or the toner particles and the intermediate transfer. The adhesion to the body does not become too weak and the graininess is improved.

Silica particles include silica particles A prepared by a sol-gel method having a median diameter of 90 to 180 nm on the number basis, and silica particles prepared by a sol / gel method having a median diameter of 60 to 110 nm on the basis of number. B is preferably used. In this case, it is preferable to add the silica particles A in an amount of 0.03 to 1.0% by mass and the silica particles B in an amount of 0.5 to 3.0% by mass with respect to the toner base particles. When the diameter is larger or the amount added is larger, the fluidity is lowered. When the diameter is smaller or the amount added is smaller, a sufficient spacer effect cannot be obtained.
Further, it is preferable that the amount of silica particles A added is smaller than the amount of silica particles B added in order to form a stationary layer having appropriate voids.

(Method for adding silica particles)
As the external addition mixing process of the silica particles to the toner base particles according to the present invention, a normal method of adding and mixing external additives to the toner base particles can be used. For example, as a method for adding silica particles, there is a dry method in which silica particles are added in powder form to dried toner base particles. As a mixing device, for example, shearing is performed on particles to be processed such as a Henschel mixer. A mixing device capable of applying force can be used. The mixing time and the rotational peripheral speed of the stirring blade are appropriately set according to the type and physical properties of the toner base particles and silica particles. When multiple types of external additives are used, all the external additives may be mixed at once with the toner particles, or divided and mixed in multiple times according to each external additive. It may be processed. Further, as will be described later, other general external additives can be added in the same manner for the purpose of improving charging performance and fluidity.

[Toner base particles]
It is preferable that the toner base particles contain a crystalline polyester resin because the flexibility of the toner base particles is improved and the silica particles are suitably fixed, and from the viewpoint of low-temperature fixability.
The toner base particles according to the present invention preferably contain at least a binder resin, a colorant, and a release agent. Further, the toner base particles according to the present invention can contain an internal additive such as a charge control agent and a release agent, and other external additives, if necessary.

  Examples of the method for producing toner base particles include a pulverization method, an emulsion polymerization aggregation method, a suspension polymerization method, and a dissolution suspension method. As a method for producing toner base particles according to the present invention, a build-up type toner production method such as an emulsion polymerization aggregation method rather than a pulverization method, a suspension method, and the like from the viewpoint of control of the toner particle size reduction and circularity A polymerization method is preferred.

  The toner base particles according to the present invention preferably have a core / shell structure.

The particle size of the toner base particles according to the present invention is preferably small for the purpose of improving the image quality, but the median diameter on the volume basis of the toner base particles is in the range of 3 to 7 μm. In addition, fluidity and adhesion can be suitably used, and as a result, development, transfer, and cleaning are not difficult, which is preferable. The median diameter of the toner base particles on the volume basis is more preferably in the range of 4 to 7 μm from the above viewpoint.
The median diameter on the volume basis of the toner base particles can be measured by the same method as the median diameter on the volume basis of the toner particles described above.

  The average circularity of the toner base particles is preferably 0.945 or more from the standpoint that it is better to have a more spherical shape from the standpoint of rising of charge and fluidity. The average circularity of the toner base particles can be measured by the same method as the method for measuring the average circularity of the toner particles described above.

(Binder resin)
As the binder resin contained in the toner base particles according to the present invention, for example, when the toner base particles are produced by a pulverization method, a dissolution suspension method, an emulsion aggregation method, or the like, a styrenic resin or (meth) acrylic resin is used. Resin, styrene- (meth) acrylic copolymer resin, vinyl resin such as olefin resin, polyester resin, polyamide resin, carbonate resin, polyether, polyvinyl acetate resin, polysulfone, epoxy resin, polyurethane Various known resins such as resins and urea resins can be used. These can be used alone or in combination of two or more. In particular, it is preferable to use, for example, a styrene acrylic resin or a polyester resin from the viewpoint of the mechanical strength of the toner particles and the affinity with the wax described later.

  For example, when the toner base particles are produced by a suspension polymerization method, an emulsion polymerization aggregation method, or the like, as a polymerizable monomer for obtaining a binder resin, for example, styrene, o-methylstyrene, m-methyl Styrene, p-methylstyrene, α-methylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, p- Styrene or styrene derivatives such as n-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene; methyl methacrylate, ethyl methacrylate, n methacrylate -Butyl, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, meta Methacrylate derivatives such as n-octyl acrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate; methyl acrylate, ethyl acrylate, acrylic Acrylic acid ester derivatives such as isopropyl acid, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, and phenyl acrylate; ethylene Olefins such as vinyl chloride, propylene and isobutylene; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide, vinyl fluoride and vinylidene fluoride; vinyl propionate, acetic acid Vinyl esters such as vinyl and vinyl benzoate; Vinyl ethers such as vinyl methyl ether and vinyl ethyl ether; Vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and vinyl hexyl ketone; N-vinyl carbazole, N-vinyl indole, N -N-vinyl compounds such as vinyl pyrrolidone; vinyl compounds such as vinyl naphthalene and vinyl pyridine; and vinyl monomers such as acrylic acid such as acrylonitrile, methacrylonitrile, acrylamide, or methacrylic acid derivatives. . These vinyl monomers can be used alone or in combination of two or more.

  Further, as the polymerizable monomer for obtaining the binder resin, it is preferable to use a combination of the polymerizable monomer having an ionic dissociation group. The polymerizable monomer having an ionic dissociation group has, for example, a substituent such as a carboxy group, a sulfonic acid group, and a phosphoric acid group as a constituent group, and specifically includes acrylic acid, methacrylic acid, maleic acid. Acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester, styrenesulfonic acid, allylsulfosuccinic acid, 2-acrylamido-2-methylpropanesulfonic acid, acid phosphooxyethyl methacrylate And 3-chloro-2-acid phosphooxypropyl methacrylate.

  Furthermore, as a polymerizable monomer, divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, neopentyl A binder resin having a crosslinked structure can also be obtained using a polyfunctional vinyl such as glycol diacrylate.

  The binder resin that can be suitably used for the toner base particles of the present invention preferably contains a binder resin having a hydrophilic polar group as a constituent component, and the hydrophilic polar group is preferably a carboxy group.

  Specific examples of the polymerizable monomer having a carboxy group used in the binder resin include acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumaric acid, and maleic acid monoalkyl ester. And itaconic acid monoalkyl ester.

(Coloring agent)
A colorant can be added to the toner of the present invention. A known colorant can be used as the colorant.

  Specifically, examples of the colorant contained in the yellow toner include C.I. I. Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, 162, C.I. I. Pigment yellow 14, 17, 74, 93, 94, 138, 155, 180, 185, and the like. These can be used alone or in combination of two or more. Among these, C.I. I. Pigment Yellow 74 is preferable.

  The content of the colorant contained in the yellow toner is preferably 1 to 10 parts by mass, more preferably 2 to 8 parts by mass with respect to 100 parts by mass of the binder resin.

  Specifically, examples of the colorant contained in the magenta toner include C.I. I. Solvent Red 1, 49, 52, 58, 63, 111, 122, C.I. I. Pigment Red 5, 48: 1, 53: 1, 57: 1, 122, 139, 144, 149, 166, 177, 178, 222, and the like. These can be used alone or in combination of two or more. Among these, C.I. I. Pigment Red 122 is preferable.

  The content of the colorant contained in the magenta toner is preferably 1 to 10 parts by mass, more preferably 2 to 8 parts by mass with respect to 100 parts by mass of the binder resin.

  Specifically, examples of the colorant contained in the cyan toner include C.I. I. Pigment blue 15: 3.

  The content of the colorant contained in the cyan toner is preferably 1 to 10 parts by mass, more preferably 2 to 8 parts by mass with respect to 100 parts by mass of the binder resin.

  Examples of the colorant contained in the black toner include carbon black, magnetic material, and titanium black. Examples of carbon black include channel black, furnace black, acetylene black, thermal black, and lamp black. Examples of magnetic materials include ferromagnetic metals such as iron, nickel, and cobalt, alloys containing these ferromagnetic metals, compounds of ferromagnetic metals such as ferrite and magnetite, and ferromagnetic materials that do not contain ferromagnetic metals but are heat treated. The alloy shown etc. are mentioned. Examples of alloys that exhibit ferromagnetism by heat treatment include Heusler alloys such as manganese-copper-aluminum and manganese-copper-tin, and chromium dioxide.

  The content of the colorant contained in the black toner is preferably 1 to 10 parts by mass, more preferably 2 to 8 parts by mass with respect to 100 parts by mass of the binder resin.

(Charge control agent)
The charge control agent is not particularly limited as long as it can give positive or negative charge by frictional charging, and various known positive charge control agents and negative charge control agents can be used.

  The content of the charge control agent is preferably 0.01 to 30 parts by mass, more preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the binder resin.

(Release agent)
Various known waxes can be used as the release agent.

  Examples of the wax include polyolefin waxes such as polyethylene wax and polypropylene wax, branched hydrocarbon waxes such as microcrystalline wax, long chain hydrocarbon waxes such as paraffin wax and sazol wax, and dialkyls such as distearyl ketone. Ketone wax, carnauba wax, montan wax, behenate behenate, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18-octadecanedioldi Ester waxes such as stearate, tristearyl trimellitic acid, distearyl maleate, ethylenediamine behenylamide, tristearyl trimellitic acid Such as amide-based waxes such as bromide and the like.

  It is preferable that content of a mold release agent is 0.1-30 mass parts with respect to 100 mass parts of binder resin, More preferably, it is 1-10 mass parts.

(Other external additives)
In addition to the silica particles described above, other external additives may be added to the toner of the present invention for the purpose of improving fluidity and chargeability. Examples of other external additives include inorganic oxide fine particles such as silica fine particles, alumina fine particles, and titanium oxide fine particles, inorganic stearate compound fine particles such as aluminum stearate fine particles and zinc stearate fine particles, or strontium titanate and titanic acid. Examples include inorganic fine particles such as inorganic titanic acid compound fine particles such as zinc.

  These inorganic fine particles are preferably those subjected to surface treatment with a silane coupling agent, a titanium coupling agent, a higher fatty acid, silicone oil, or the like from the viewpoint of heat-resistant storage stability and environmental stability.

  The amount of other external additives added is 0.05 to 5 parts by mass, preferably 0.1 to 3 parts by mass, with respect to 100 parts by mass of the toner base particles. Further, various other additives may be used in combination.

<Method for producing toner for developing electrostatic latent image>
The method for producing the toner according to the present invention is not particularly limited, and a known method can be adopted, but an emulsion polymerization aggregation method or an emulsion aggregation method can be preferably employed.

  The emulsion polymerization aggregation method preferably used in the method for producing a toner according to the present invention is a dispersion of fine particles of a binder resin produced by an emulsion polymerization method (hereinafter also referred to as “binder resin fine particles”) as a colorant. The fine particles (hereinafter also referred to as “colorant fine particles”) are mixed with a dispersion liquid of a release agent such as a dispersion liquid and wax, and the toner particles are aggregated until a desired particle diameter is obtained. In this method, toner particles are manufactured by controlling the shape by fusing.

Further, the emulsion aggregation method preferably used as a method for producing the toner according to the present invention is a method in which a binder resin solution dissolved in a solvent is dropped into a poor solvent to obtain a resin particle dispersion, and the resin particle dispersion and the colorant dispersion And a release agent dispersion such as wax, and agglomerate until a desired toner particle diameter is obtained. Further, the shape is controlled by fusing the binder resin fine particles to produce toner particles. Is the method.
Either method can be applied to the toner of the present invention.

An example of using the emulsion polymerization aggregation method as a method for producing the toner of the present invention is shown below.
(1) Step of preparing a dispersion liquid in which fine particles of colorant are dispersed in an aqueous medium (2) Dispersion in which binder resin fine particles containing an internal additive are dispersed in an aqueous medium as required Step of preparing liquid (3) Step of preparing dispersion of binder resin fine particles by emulsion polymerization (4) Mixing dispersion of fine particles of colorant and dispersion of binder resin fine particles, Step of forming toner base particles by agglomerating, associating and fusing the fine particles of the resin and the binder resin fine particles (5) The toner base particles are filtered off from the dispersion system (aqueous medium) of the toner base particles to obtain a surfactant, etc. (6) Step of drying toner base particles (7) Step of adding external additive to toner base particles

  When the toner is produced by the emulsion polymerization aggregation method, the binder resin fine particles obtained by the emulsion polymerization method may have a multilayer structure of two or more layers made of binder resins having different compositions. For example, a binder resin fine particle having a two-layer structure is prepared by preparing a dispersion of resin particles by emulsion polymerization treatment (first-stage polymerization) according to a conventional method, and adding a polymerization initiator to the dispersion. It can be obtained by adding a polymerizable monomer and polymerizing this system (second stage polymerization).

  In addition, toner particles having a core / shell structure can be obtained by an emulsion polymerization aggregation method. Specifically, the toner particles having a core / shell structure are firstly binder resin fine particles for core particles and fine particles of colorant. The core particles are prepared by agglomerating, associating and fusing, and then the binder resin fine particles for the shell layer are added to the core particle dispersion to agglomerate the binder resin fine particles for the shell layer on the core particle surface. , And can be obtained by forming a shell layer that covers the surface of the core particles by fusing.

An example of using a pulverization method as a method for producing the toner of the present invention is shown below.
(1) A step of mixing a binder resin, a colorant and, if necessary, an internal additive by a Henschel mixer or the like (2) a step of kneading the obtained mixture while heating with an extrusion kneader or the like (3) obtained Step of coarsely pulverizing the kneaded product with a hammer mill or the like, and further pulverizing with a turbo mill pulverizer or the like (4) The obtained pulverized product is finely classified using, for example, an airflow classifier utilizing the Coanda effect. Step of forming toner base particles (5) Step of adding external additive to toner base particles

<Outline of two-component developer for electrostatic image development>
The toner for developing an electrostatic latent image of the present invention can be used as a non-magnetic one-component developer, but can be suitably used as a two-component developer for developing an electrostatic image containing a carrier.

[Career]
The carrier is composed of a magnetic material, but resin-coated carrier particles in which the surface of a carrier core made of the magnetic material is coated with a resin, or a resin in which a magnetic fine powder is dispersed in a resin It can also be composed of dispersed carrier particles. From the viewpoint of controlling the true specific gravity to 4.25 to 5 g / cm ³ and the porosity to 8% or less, it is preferably constituted by resin-coated carrier particles.
The carrier particles may contain an internal additive such as a resistance adjuster as necessary.

(Career core)
The carrier core constituting the carrier particles is composed of various ferrites in addition to metal powder such as iron powder, for example. Among these, ferrite is preferable.
As the ferrite, ferrite containing heavy metals such as copper, zinc, nickel and manganese and light metal ferrite containing alkali metals or alkaline earth metals are preferable.
Ferrite is a compound represented by the formula: (MO) x (Fe ₂ O ₃ ) y, and the molar ratio y of Fe ₂ O ₃ constituting the ferrite is preferably 30 to 95 mol%. Ferrite having a composition ratio y in the above range has a merit that a desired magnetization can be easily obtained, so that a carrier that hardly causes carrier adhesion can be produced. M in the formula is manganese (Mn), magnesium (Mg), strontium (Sr), calcium (Ca), titanium (Ti), copper (Cu), zinc (Zn), nickel (Ni), aluminum (Al) , Silicon (Si), zirconium (Zr), bismuth (Bi), cobalt (Co), lithium (Li) and the like, and these can be used alone or in combination.

(Carrier coating resin)
By using a highly hydrophobic alicyclic methacrylic acid ester compound as a monomer for obtaining a coating resin, the moisture adsorption amount of the carrier particles is reduced, and the environmental difference in chargeability is reduced. A decrease in charge amount in a wet environment is suppressed. In addition, a resin obtained by polymerizing a monomer containing an alicyclic methacrylic acid ester compound has an appropriate mechanical strength, and the surface of the carrier particles is refreshed by appropriate film abrasion as a coating material. The
As the alicyclic methacrylic acid ester compound, those having a cycloalkyl group having 5 to 8 carbon atoms are preferable. Specific examples include cyclopentyl methacrylate, cyclohexyl methacrylate, cycloheptyl methacrylate, cyclooctyl methacrylate and the like. It is done. Among these, cyclohexyl methacrylate is particularly preferable from the viewpoint of mechanical strength and environmental stability of the charge amount.

<Image forming method>
The toner of the present invention can be suitably used in a general electrophotographic image forming method together with black toner, yellow toner, magenta toner and cyan toner.

  The embodiments to which the present invention can be applied are not limited to the above-described embodiments, and can be appropriately changed without departing from the spirit of the present invention.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "mass part" or "mass%" is represented.

<< Preparation of toner base particles 1 >>
(Preparation of colorant fine particle dispersion (A1))
A solution obtained by stirring and dissolving 11.5 parts by mass of sodium n-dodecyl sulfate in 160 parts by mass of ion-exchanged water was stirred, and 24.5 parts by mass of copper phthalocyanine was gradually added to the solution. Subsequently, by performing a dispersion treatment using a stirring device “CLEARMIX W-Motion CLM-0.8” (manufactured by M Technique Co., Ltd.), a “colorant fine particle dispersion (volume-based median diameter of 126 nm) A1) "was prepared.

(Preparation of resin fine particle dispersion [B3] for core)
(1) First-stage polymerization Into a 5 L reaction vessel equipped with a stirrer, temperature sensor, cooling pipe, and nitrogen introduction device, 4 g of polyoxyethylene (2) sodium dodecyl ether sulfate and 3000 g of ion-exchanged water were charged under a nitrogen stream. The internal temperature was raised to 80 ° C. while stirring at a stirring speed of 230 rpm. After raising the temperature, 10 g of potassium persulfate dissolved in 200 g of ion-exchanged water was added to obtain a liquid temperature of 75 ° C.
・ Styrene 568g
・ 164 g of n-butyl acrylate
・ Methacrylic acid 68g
After the monomer mixed liquid consisting of 1 was added dropwise over 1 hour, polymerization was carried out by heating and stirring at 75 ° C. for 2 hours to prepare a dispersion of resin particles [B1].

(2) Second-stage polymerization A solution prepared by dissolving 2 g of polyoxyethylene (2) sodium dodecyl ether sulfate in 3000 g of ion-exchanged water in a 5 L reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introducing device. After charging and heating to 80 ° C., 42 g of the above resin particles [B1] (in terms of solid content) and 70 g of wax “HNP-0190” (manufactured by Nippon Seiwa Co., Ltd.)
・ Styrene 195g
・ 91g of n-butyl acrylate
・ Methacrylic acid 20g
・ 3g of n-octyl mercaptan
A solution prepared by dissolving the monomer solution at 80 ° C. in a monomer solution is mixed and dispersed for 1 hour by a mechanical disperser “CLEARMIX” (manufactured by M Technique Co., Ltd.) having a circulation path. A dispersion liquid containing oil droplets) was prepared.

  Next, an initiator solution in which 5 g of potassium persulfate was dissolved in 100 g of ion-exchanged water was added to this dispersion, and the system was heated and stirred at 80 ° C. for 1 hour to carry out polymerization, whereby resin particles [ A dispersion of B2] was prepared.

(3) Third-stage polymerization Further, a solution prepared by dissolving 10 g of potassium persulfate in 200 g of ion-exchanged water is added to the dispersion of the resin particles [B2].
・ 298 g of styrene
・ 137g of n-butyl acrylate
・ N-stearyl acrylate 50g
・ Methacrylic acid 64g
・ 6g of n-octyl mercaptan
A monomer mixture consisting of was added dropwise over 1 hour. After completion of the dropwise addition, polymerization was performed by heating and stirring for 2 hours, and then cooled to 28 ° C. to obtain a resin fine particle dispersion for core [B3].

(Synthesis of amorphous polyester resin [C1])
In a reaction vessel equipped with a cooling tube, a stirrer and a nitrogen introducing tube, 360 parts by mass of bisphenol A propylene oxide 2-mol adduct, 80 parts by mass of terephthalic acid, 55 parts by mass of fumaric acid, and titanium tetraisopropoxy as a polycondensation catalyst. 2 parts by mass of the dough was divided into 10 portions and reacted at 200 ° C. for 10 hours while distilling off the water generated under a nitrogen stream. Subsequently, it was made to react under reduced pressure of 13.3 kPa (100 mmHg), and it took out when the softening point became 104 degreeC, and prepared amorphous polyester resin [C1].

(Preparation of amorphous polyester resin particle dispersion [C2])
100 parts by mass of the amorphous polyester resin [C1] obtained above was dissolved in 400 parts by mass of ethyl acetate. Subsequently, 25 mass parts of 5.0 mass% sodium hydroxide aqueous solution was added, and the resin solution was prepared. This resin solution was put into a container having a stirring device, and 638 parts by mass of a 0.26% by mass aqueous sodium lauryl sulfate solution was dropped and mixed over 30 minutes while stirring the resin solution. During the dropwise addition of the sodium lauryl sulfate aqueous solution, the liquid in the reaction vessel became cloudy, and after adding the entire amount of the sodium lauryl sulfate aqueous solution, an emulsion was prepared in which the resin solution particles were uniformly dispersed. Next, the emulsion is heated to 40 ° C., and ethyl acetate is distilled off under a reduced pressure of 150 hPa using a diaphragm vacuum pump “V-700” (manufactured by BUCHI). A crystalline polyester resin particle dispersion [C2] was obtained.

(Synthesis of crystalline polyester resin [D1])
In a three-necked flask, 300 g of 1,9-nonanediol, 250 g of dodecanedioic acid, and catalyst Ti (OBu) ₄ (0.014% by mass with respect to the carboxylic acid monomer) were added, Air was depressurized. Further, under an inert atmosphere with nitrogen gas, the mixture was refluxed at 180 ° C. for 6 hours with mechanical stirring. Thereafter, unreacted monomer components were removed by distillation under reduced pressure, and the temperature was gradually raised to 220 ° C., followed by stirring for 12 hours. Crystalline polyester resin [D1] was obtained by cooling in the viscous state. The obtained crystalline polyester resin [D1] had a weight average molecular weight (Mw) of 19,500 and a melting point of 75 ° C.

(Preparation of crystalline polyester resin particle dispersion [D2])
Using the crystalline polyester resin [D1] obtained above, a crystalline polyester resin particle dispersion [D2] was obtained in the same manner as in the preparation of the amorphous polyester resin particle dispersion [C2].

(Aggregation / fusion process)
In a reaction vessel equipped with a stirrer, a temperature sensor, and a cooling tube, 300 parts by mass of the core resin fine particle dispersion [B3] in terms of solids and 60% of the crystalline polyester resin particle dispersion [D2] in terms of solids And 2000 parts by mass of ion-exchanged water were added, and a 5 mol / liter sodium hydroxide aqueous solution was added to adjust the pH to 10. Thereafter, 40 parts by mass of the colorant fine particle dispersion (A1) was added in terms of solid content. Next, an aqueous solution in which 60 parts by mass of magnesium chloride was dissolved in 60 parts by mass of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring. Thereafter, the temperature was raised after being allowed to stand for 3 minutes, and the temperature of the system was raised to 80 ° C. over 60 minutes, and the particle growth reaction was continued while maintaining 80 ° C. In this state, the particle size of the associated particles was measured with “Multisizer 3” (manufactured by Beckman Coulter), and when the median diameter (D ₅₀ ) on the volume basis became 5.5 μm, the amorphous polyester resin was used. An aqueous solution in which 190 parts by mass of sodium chloride was dissolved in 760 parts by mass of ion-exchanged water when 30 parts by mass of the particle dispersion [C2] was charged over 30 minutes and the supernatant of the reaction solution became transparent. Was added to stop grain growth. Further, the temperature is raised and the mixture is heated and stirred in a state of 90 ° C. to advance the fusion of the particles, and the average circularity measurement apparatus “FPIA-2100” (manufactured by Sysmex) is used (HPF detection). When the average circularity reached 0.965, the mixture was cooled to 30 ° C. to prepare a dispersion of toner base particles.

(Washing / drying process)
The dispersion of toner base particles produced in the aggregation / fusion process was subjected to solid-liquid separation with a centrifugal separator to form a wet cake of toner base particles. The wet cake was washed with ion-exchanged water at 35 ° C. until the electric conductivity of the filtrate reached 5 μS / cm with the centrifuge, and then transferred to “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.). The toner base particles 1 were prepared by drying to 0.5% by mass.

<< Production of Toner 1 >>
(Preparation of silica particles 1 prepared by the sol-gel method)
(1) 630 parts by mass of methanol and 90 parts by mass of water were added to and mixed with a 3 liter reactor equipped with a stirrer, a dropping funnel, and a thermometer. To this solution, 950 parts by mass of tetramethoxysilane was added with stirring, followed by hydrolysis to obtain a suspension of silica particles. Subsequently, it heated at 60-70 degreeC, 390 mass parts of methanol was distilled off, and the aqueous suspension of the silica particle was obtained.
(2) To this aqueous suspension, 11.6 parts by mass of methyltrimethoxysilane (corresponding to 0.1 molar ratio with respect to tetramethoxysilane) was added dropwise at room temperature to hydrophobize the surface of the silica particles. .
(3) After adding 1400 parts by mass of methyl isobutyl ketone to the dispersion thus obtained, the mixture was heated to 80 ° C. to distill off methanol water. To the obtained dispersion, 280 parts by mass of hexamethyldisilazane was added at room temperature, heated to 120 ° C. and reacted for 3 hours to trimethylsilylate the silica particles. Thereafter, the solvent was distilled off under reduced pressure to prepare silica particles 1.
When the volume average primary particle size and the degree of dispersion of the silica particles 1 obtained by the above method were measured, the volume average primary particle size (D ₅₀ ) was 85 nm and the standard deviation was 14 nm.

(Preparation of silica particles 2 prepared by the sol-gel method)
In the preparation of the silica particles 1, the volume average particle diameter is adjusted by controlling the mass ratio of alkoxysilane, ammonia, alcohol, and water in the hydrolysis and polycondensation steps, the reaction rate, the stirring rate, and the supply rate. The silica particle 2 described in 1 was prepared.

(External additive addition process)
Silica particles 1 and 2 shown in Table 1 were added as external additives to “toner base particles 1” produced as described above.
Further, as other external additives, 0.5% by mass of hydrophobic titanium oxide (HMDS treatment, hydrophobization degree 55%, number average primary particle size = 20 nm) is added to the toner base particles 1, and the Henschel mixer type is added. “FM20C / I” (manufactured by Nippon Coke Kogyo Co., Ltd.), setting the rotational speed so that the peripheral speed of the blade tip is 40 m / s and stirring for 15 minutes. Was made.
The product temperature when mixing the external additive is set to 40 ± 1 ° C., and when it reaches 41 ° C., the cooling water is supplied to the outer bath of the Henschel mixer at a flow rate of 5 L / min to 39 ° C. In such a case, the temperature inside the Henschel mixer was controlled by flowing cooling water at a flow rate of 1 L / min.
The toner particles contained in the obtained toner 1 had a median diameter (D ₅₀ ) on the volume basis of 5.6 μm and an average circularity of 0.965.

<< Production of Toners 2-9 >>
In the production of the toner 1, the median diameter and the production method on the basis of the number of the silica particles 1 prepared by the sol-gel method and the silica particles 2 prepared by the sol-gel method were changed as shown in Table 1. In the same manner, toners 2 to 9 were produced.
The toner particles contained in each of the obtained toners 2 to 9 had the same median diameter (D ₅₀ ) and average circularity on the volume basis as the toner particles contained in the toner 1.

<< Measurement of physical properties of toners 1-9 >>
The following physical properties were measured for the toners 1 to 9 produced as described above. Table 1 shows the measurement results.

(Particle size of silica particles released by ultrasonic dispersion)
Each of the produced toners 1 to 9 was subjected to ultrasonic dispersion treatment in water as described below, and S ₁ and S _{3 in} the formula (1) according to the present invention were measured.
That is, 3 g of toner was wetted with 40 g of a 0.2% aqueous solution of polyoxyethyl phenyl ether in a 50 mL screw tube bottle and stirred well. Then, it moved to the 60 mL disposable cup, and it adjusted so that the chip | tip (phi) 36 of an ultrasonic converter might be immersed in a solution about 3 cm in ultrasonic type homogenizer OS-1200. Thereafter, the ultrasonic energy was adjusted to 100 W, and ultrasonic waves were applied for 1 minute and 3 minutes, respectively. Each dispersion was transferred to a 15 ml test tube and centrifuged at 3000 rpm for 10 minutes in a centrifuge CN-1040, and then the supernatant was collected. The collected supernatant was dispersed by applying ultrasonic waves for 3 minutes at an output of 80 W with an ultrasonic cleaner US-1, and then the particle size distribution was measured with a dynamic light scattering nanotrack particle size analyzer UPA-150. . At that time, the measurement conditions were set such that the refractive index of the particles was 1.51 and the specific gravity was 2.0. Among the particle size distributions obtained for the ultrasonic dispersion treatment for 1 minute and 3 minutes, the peak top particle sizes in the range of 70 to 160 nm were defined as S ₁ and S ₃ , respectively.
Table 1 shows the values of S ₁ , S _3, and S ₁ / S ₃ for each of the toners 1 to 9.

<< Evaluation of Toners 1-9 >>
Toners 1 to 9 prepared as described above are respectively added to a ferrite carrier having a volume average particle diameter of 30 μm so that the toner concentration becomes 7% by mass, and mixed for 30 minutes using a V-type mixer. Thus, developers 1 to 9 were produced.
The produced developers 1 to 9 were evaluated as follows. Each evaluation result is shown in Table 1.

(1) Cleanability Using “bizhub PRO C6500” (manufactured by Konica Minolta) loaded with developers 1 to 9, an image with a pixel rate of 5% in a normal temperature and humidity environment (temperature 25 ° C., humidity 50% RH) Was printed on A4 size fine paper (64 g / m ² ), a solid test image (grit voltage 450 V, development potential: 350 V) was output, and the solid image and the photoreceptor were visually confirmed. The cleaning blade was installed so that the angle formed with the photosensitive member was 7.5 ° and the contact pressure was variable from 0.039 to 0.069 MPa. The confirmation result was evaluated according to the following criteria. If the contact pressure of the cleaning blade is 0.069 MPa or less and there is no toner slip on the test image (in the case of “◎” or “「 ”according to the following criteria), it is determined that there is no practical problem.
A: No contact of toner is visually recognized on the test image when the contact pressure is 0.039 MPa. ○: No slip of toner is observed on the test image when the contact pressure is 0.069 MPa. X: When the contact pressure is 0.069 MPa. Toner slip is visible on the test image

(2) Fluidity With respect to the developers 1 to 9, the bulk density was measured by “Kawakita type bulk density measuring machine IH2000 type” (manufactured by Seishin Enterprise Co., Ltd.) and used as an index of fluidity. Specifically, each of developers 1 to 9 is placed on a 120-mesh sieve, vibrated for 90 seconds at a vibration intensity of 6, and then stopped to stand for 30 seconds. The ground bulk density (toner mass / volume) Asked. The results were evaluated according to the following criteria. In addition, fluidity | liquidity is so favorable that the crushed bulk density is large, and specifically, when larger than 0.35 (in the case of "(circle)" on the following reference | standard), it evaluated as practical.
○: Grinded bulk density is greater than 0.35 x: Grinded bulk density is 0.35 or less

(3) Summary As is apparent from the results in Table 1, the toners 7 to 9, which are comparative examples, cannot achieve both fluidity and cleaning properties, but the toners 1 to 6 of the present invention have fluidity and cleaning properties. It can be seen that both are compatible.

DESCRIPTION OF SYMBOLS 101 Member to be cleaned 102 Cleaning blade 103 Nip part 201 Toner particle 202 External additive 203 Static layer 300 Toner particle 301 Toner base particle A, B Silica particle prepared by sol-gel method

Claims (3)

A toner base particle and an external additive attached to the surface of the toner base particle; a volume-based median diameter in the range of 3 to 7 μm; and an average circularity in the range of 0.945 to 1.00 An electrostatic latent image developing toner containing toner particles,
As the external additive, containing silica particles prepared by a sol-gel method in which the median diameter on the number basis is in the range of 70 to 160 nm,
A toner for developing an electrostatic latent image, wherein the particle size distribution of the silica particles liberated by ultrasonic dispersion treatment in water satisfies the following formula (1).
Equation _{(1): 1.1 ≦ S 1} / S 3 ≦ 2.8
(In Formula (1), S ₁ represents the particle size of the peak top in the particle size distribution of the silica particles released in 1 minute of ultrasonic dispersion treatment, and S ₃ represents the silica released in 3 minutes of ultrasonic dispersion treatment. (This represents the peak top particle size in the particle size distribution.)   2. The electrostatic latent image developing toner according to claim 1, wherein the silica particles contain silica particles prepared by two kinds of sol-gel methods having different median diameters based on the number.   A two-component developer for developing an electrostatic latent image, comprising the toner for developing an electrostatic latent image according to claim 1 or 2 and a carrier.

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