JP6665602B2 - Toner for developing electrostatic images and two-component developer for developing electrostatic images - Google Patents

Description

  The present invention relates to a toner for developing an electrostatic image and a two-component developer for developing an electrostatic image. More specifically, the present invention relates to an electrostatic image developing toner having a high adhesion and a high image quality in a high-speed printing or a high-coverage printing, even if the toner is a high-adhesive electrostatic image developing toner into which a crystalline substance is introduced. Related to toner and the like.

  In recent years, low-temperature fixable toners capable of high-speed printing and realizing low environmental load have been studied. As a means for obtaining a low-temperature fixing toner, introduction of a crystalline resin having excellent sharp melt properties into a binder resin has been actively studied. Since the crystalline resin has a polar group in its structure, it increases the hygroscopicity of the toner. Since the powder containing water has an increased adhesive force, the adhesive force of the toner base particles increases, and the transportability and dischargeability deteriorate. Therefore, in the case of the toner including the toner base particles containing the crystalline resin, it is difficult to handle in each process of electrophotography such as discharge and conveyance.

Also, with the spread of digital printing, higher quality of output images is increasingly demanded. As the toner base particles have a smaller particle size, the reproducibility of fine dots is improved, and a fine and high-quality image is formed.
However, when the particle diameter of the toner base particles decreases, the specific surface area increases, and thus the adhesion of the toner base particles increases. For this reason, there is a development trend that makes toner base particles having a small particle diameter more difficult to handle as powder.

  On the other hand, as recent market demands, electrophotographic development is required to increase the printing speed as described above and to output high coverage images that consume a large amount of toner. In order to cope with such high-speed printing and mass consumption of toner, the toner supply to the developing process needs to be performed quickly and smoothly.

In view of the above, there has been disclosed a technique of using a toner by devising each process of electrophotography to compensate for a defect in powder characteristics of the toner base particles containing the crystalline resin (for example, Patent Document 1). And Patent Document 2.).
However, there is a limit to the devising of each process of electrophotography, and the toner replenishing property and the image quality in high-speed printing or high-coverage printing are insufficient.
On the other hand, there is room for improvement in the powder characteristics of the toner itself.

JP 2014-17853 A JP-A-2005-4964

  The present invention has been made in view of the above-described problems and circumstances, and the problem to be solved is that even in the case of a toner for developing an electrostatic image having a high adhesive force into which a crystalline substance is introduced, even in high-speed printing or high-coverage printing. Another object of the present invention is to provide a toner for developing an electrostatic charge image having good toner replenishability and image quality.

In order to solve the above-mentioned problems, the present inventor, in the course of examining the cause of the above-mentioned problems and the like, responds to the external force of the powder even in the case of a toner for developing an electrostatic image with a high adhesive force into which a crystalline substance is introduced. If the fluidization degree, which indicates the property, and the avalanche energy change, which indicates the easiness of behaving like a powdery liquid, are within a specific range, the toner for developing an electrostatic image can be consumed at high speed and in large quantities. As a result, it has been found that stable toner replenishment can be ensured and, in high-speed printing and high-coverage printing, toner replenishment and image quality can be improved.
That is, the above object according to the present invention is solved by the following means.

1. A toner base particle containing a binder resin, a release agent, and a crystalline resin of a different type from the release agent, and an electrostatic charge image developing method including an external additive attached to the surface of the toner base particle Toner,
As the external additive, titanium oxide particles having an average aspect ratio (the number average major axis / the number average minor axis) derived from the ratio of the number average major axis to the number average minor axis are in the range of 2 to 15 A spherical silica particle having a number average particle diameter within a range of 60 to 100 nm, which is contained in the range of 0.10 to 0.80 parts by mass with respect to the toner base particle, Contained in the range of 0.05 to 0.80 parts by mass,
The titanium oxide particles have a rutile-type crystal structure,
The fluidization degree measured using a rotating drum / image analysis type powder fluidity measurement device is in the range of 0.50 to 0.90 cm / rpm, and
An avalanche energy change amount measured by using a rotating drum / image analysis type powder fluidity measuring device is within a range of 12.5 to 25.0 kJ / kg. .

  2. 2. The toner according to claim 1, wherein the fluidization degree is in a range of 0.65 to 0.90 cm / rpm.

  3. 3. The electrostatic image developing toner according to claim 1, wherein a volume-based median diameter (D50% diameter) of the toner base particles is in a range of 4.5 to 8.0 μm.

  4. 4. The toner for developing an electrostatic image according to any one of items 1 to 3, wherein the crystalline resin contains a crystalline polyester resin.

  5. 5. The electrostatic image development according to claim 4, wherein the crystalline polyester resin is a hybrid crystalline polyester resin in which an amorphous resin segment and a crystalline polyester segment are chemically bonded. toner.

6 . 6. A two-component developer for developing an electrostatic image, comprising: the toner for developing an electrostatic image according to any one of Items 1 to 5 ; and carrier particles.

According to the above-described means of the present invention, a toner for developing an electrostatic image having good toner replenishability and image quality in high-speed printing or high-coverage printing even with a toner base particle having a high adhesive force into which a crystalline substance is introduced is provided. can do.
Although the mechanism of manifesting or acting the effects of the present invention has not been clarified, it is speculated as follows.

  For example, in order for toner inside the bottle to be conveyed and supplied (discharged) to an external conveying device by rotation of the toner bottle (hereinafter, also simply referred to as “bottle”), it is desirable that the toner be easily fluidized. It is. Generally, a powder such as a toner approaches a fluid behavior like a liquid as the air becomes entrapped. If the degree of fluidization, which is the ease with which the powder contains air with respect to the rotation of the bottle, is within a specified range, it is assumed that the toner exhibits ideal transport / discharge behavior.

Further, in the transport in the bottle, the toner must be moved in the direction of the rotation axis. Therefore, it is not preferable that the toner is lifted upward while adhering to the bottle wall surface with the rotation of the bottle. When the avalanche energy change amount, which is an index of the ease with which the powder in the rotating drum collapses, is within a specified range, the fluidity is high and small-scale avalanche phenomena frequently occur. As a result, the upward movement of the toner in the bottle is small, and the rotation time of the bottle related to the conveyance of the toner is lengthened. As a result, high conveyance performance is obtained.
The event that can be solved by the present invention is not limited to the toner conveyance method based on the rotation of the toner bottle. For example, even if the toner supply container has a screw mechanism inside the toner bottle, by satisfying the constituent requirements of the present invention, the toner exhibits an ideal flow behavior as a powder, which is advantageous for conveyance and discharge.

The present inventor considers the toner transportability and dischargeability as a combination of the degree of fluidization and the fluidity, that is, “whether it contains air and it is easy to flow (easy to move)” and “whether the fluidity is high (is it easy to move). )). Thereby, the dynamic and three-dimensional behavior of the toner could be defined.
In addition, the inventor of the present invention concluded that if the degree of fluidization measured by using a rotating drum / image analysis type powder fluidity measuring device is in the range of 0.50 to 0.90 cm / rpm, the toner It has been found that the toner can smoothly flow in response to an external force for urging the toner to be discharged out of the bottle, so that the toner transportability and the dischargeability can be ensured.
If it is less than 0.50 cm / rpm, the toner starts moving poorly and does not respond ideally to an external force, and if it is more than 0.90 cm / rpm, the flushing is apt to occur due to an excessive external force response and handling becomes difficult.

  Further, when the avalanche energy change is in the range of 12.5 to 25.0 kJ / kg, the toner has sufficient fluidity, and exhibits ideal behavior when conveyed in the bottle or discharged to the outside of the bottle. Show. If it is less than 12.5 kJ / kg, the fluidity is low and the movement of the toner is poor, so that it is difficult to carry or discharge the toner. If it is more than 25.0 kJ / kg, it is difficult to stir and mix with the carrier, which is a particle larger than the toner base particles, so that it cannot be stirred properly in the developing machine, and the charging and developing performance deteriorates.

Cross-sectional schematic diagram showing an example of a cross-section of a powder fluidity measuring device for explaining the degree of fluidization Cross-sectional schematic diagram showing an example of a cross-section of a powder flowability measuring device for explaining an avalanche energy change amount

The electrostatic image developing toner of the present invention is attached to the surface of the toner base particles and the toner base particles containing a binder resin, a release agent, and a crystalline resin different from the release agent. And an average aspect ratio (the number average major axis / the number average minor axis) derived from the ratio of the number average major axis to the number average minor axis as the external additive. Diameter) is in the range of 2 to 15 and the toner base particles are contained in the range of 0.10 to 0.80 parts by mass, and the number average particle size is 60 to 100 nm. Spherical silica particles in the range of 0.05 to 0.80 parts by mass with respect to the toner base particles, wherein the titanium oxide particles have a rutile type crystal structure; Measured using an analytical powder flow measurement device 11. The degree of fluidization is within the range of 0.50 to 0.90 cm / rpm, and the avalanche energy change amount measured using a rotating drum / image analysis type powder fluidity measuring device is 12. It is characterized by being in the range of 5 to 25.0 kJ / kg. This feature is a technical feature common to or corresponding to the claimed invention.

  As an embodiment of the present invention, it is preferable that the fluidization degree is in the range of 0.65 to 0.90 cm / rpm in order to improve toner transportability and dischargeability.

  As an embodiment of the present invention, it is preferable that the volume-based median diameter (D50% diameter) of the toner base particles is in the range of 4.5 to 8.0 μm, so that both the image quality of the output image and the toner replenishing property are improved. It is preferable because it can be made more suitable.

  As an embodiment of the present invention, it is preferable to include a crystalline polyester resin as the crystalline resin since the low-temperature fixability is further improved. Further, the crystalline polyester resin is preferably a hybrid crystalline polyester resin in which an amorphous resin segment and a crystalline polyester segment are chemically bonded, because the toner replenishing property can be further improved. .

As an embodiment of the present invention, as an external additive, the average aspect ratio (number average major axis / number average minor axis) derived from the ratio of the number average major axis to the number average minor axis is in the range of 2 to 15. It is preferable that certain titanium oxide particles are contained in the range of 0.10 to 0.80 parts by mass with respect to the toner base particles because the toner replenishing property can be maintained. In addition, it is preferable that the titanium oxide particles have a rutile type crystal structure because the toner transportability and dischargeability can be further improved.
Further, as an external additive, spherical silica particles having a number average particle diameter in the range of 60 to 130 nm are contained in the range of 0.05 to 0.80 parts by mass with respect to the toner base particles. Since the adjustment of the degree and the amount of change in the avalanche energy can be suitably performed, it is preferable from the viewpoint of achieving the effects of the present invention.

  The toner for developing an electrostatic image of the present invention can be suitably contained in a two-component developer for developing an electrostatic image containing carrier particles. Thereby, even in high-speed printing and high-coverage printing, it is possible to provide a two-component developer for developing an electrostatic image having good toner replenishing properties and image quality.

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

<< Outline of toner for developing electrostatic images >>
The electrostatic image developing toner of the present invention is attached to the surface of the toner base particles and the toner base particles containing a binder resin, a release agent, and a crystalline resin different from the release agent. For developing an electrostatic image containing an external additive having a fluidization degree of 0.50 to 0.90 cm / rpm as measured using a powder fluidity measuring device of a rotating drum / image analysis system. And the avalanche energy change amount measured using a rotating drum / image analysis type powder fluidity measuring device is within a range of 12.5 to 25.0 kJ / kg. I do.

[1. Physical Properties of Toner]
<1.1. Fluidization degree>
The degree of fluidization according to the present invention is a physical property value relating to "easiness of fluidization" of powder, that is, "whether or not it contains air and easily flows (ease of movement)". Specifically, it indicates whether or not the toner easily starts moving (response to the external force) with respect to an external force that triggers the movement of the toner.
The fluidization degree will be further described with reference to FIG. 1 which shows an example of a cross section of a powder fluidity measuring device of a rotating drum / image analysis system. FIG. 1 is a cross section perpendicular to a rotation axis R of a rotary drum D filled with toner (hereinafter, also referred to as “powder”). The rotating drum D rotates in an arrow CW direction. The rotation axis of the drum is substantially parallel to the ground. When the rotation speed of the rotary drum D is gradually increased, the toner T contains air due to the toner being scattered, and the direction of the arrow U which is a direction perpendicular to the ground (hereinafter, also referred to as “upward”). ). At this time, the amount of increase in the height per unit rotation of the upper surface of the powder (toner T) (hereinafter, also referred to as “powder surface T _s ”) is referred to as “fluidization degree” according to the present invention. The larger the value, the easier the fluidization.
The toner for developing an electrostatic image of the present invention has a fluidization degree measured by using a rotating drum / image analysis type powder fluidity measuring device (hereinafter, also simply referred to as “powder fluidity measuring device”). , 0.50 to 0.90 cm / rpm. A more preferred range of the degree of fluidization is in the range of 0.65 to 0.90 cm / rpm. Within this range, the fluidized state can be easily obtained, and the toner transportability and dischargeability can be further improved.

<1.2. Avalanche Energy Change>
The “avalanche energy change amount” according to the present invention represents the easiness of behavior of the powder like a liquid, that is, “whether it is easy to move”, and is a physical property value related to the “fluidity” of the powder. It shows how much the potential energy changes in a collapse phenomenon (an avalanche phenomenon) after the toner is pulled up according to the rotation of the drum. The smaller the change in energy, the more difficult it is for the toner to be pulled upward, and the more easily the toner collapses. Such a toner can be said to be a powder having good fluidity.
The avalanche phenomenon will be described with reference to FIG. 2 showing an example of a cross section of an image analysis type powder fluidity measuring device. FIG. 2A is a cross-sectional view perpendicular to the rotation axis of the rotary drum D filled with the toner T, similarly to FIG. As shown in FIG. 2A, the rotating drum D rotates in the direction of the arrow CW. The toner T is pulled up with the rotation of the rotary drum D. With further rotation progresses, the inclination of the powder body surface T _s is increased. When the this inclination is an angle above the top of the powder body surface T _s, for example, crumbling in the direction indicated by the arrow F (FIG. 2 (b), the FIG. 2 (c) reference.). Such a phenomenon is called an avalanche phenomenon.
The electrostatic charge image developing toner of the present invention has an avalanche energy change amount of 12.5 to 25.0 kJ / kg measured using a rotating drum / image analysis type powder fluidity measuring device. .

<1.3. Measurement method>
For measurement of the degree of fluidization and the amount of change in avalanche energy, a powder fluidity measuring device of the following rotating drum and image analysis type is used.
・ Outline: Rotary drum ・ Image analysis method Powder flowability measuring device ・ Product name: Powder analyzer REVOLUTION
・ Manufacturer: Mercury Science Inc.
・ Configuration of rotating drum:
Both sides are transparent drums made of glass, and one side can be opened by screwing it into the other side, and the powder sample is sealed in a cylindrical space (332 cm ³ ) of about 10 cm in diameter and about 4 cm in thickness. ing.

(1.3.1. Method of measuring fluidization degree)
The fluidization degree according to the present invention can be measured by the following method. The measurement is performed by the following procedure using the above powder fluidity measuring device.

A toner (powder) 100 cm ³ as a measurement sample is sealed in a rotating drum made of glass on the side, and attached to the powder fluidity measuring device. The rotating drum is rotated for 10 seconds at each rotation speed while gradually changing the rotation speed from 20 rpm to 80 rpm in steps of 5 rpm. The rise of the powder surface is recorded by a CCD camera, and the height of the powder surface is quantified every 0.1 second at each rotation speed, and the average value is determined as the average height of the powder surface. The drum rotation speed (rpm) is plotted on the horizontal axis, and the average height (cm) of the powder surface is plotted on the vertical axis, and the slope of the straight line is determined by the least square method. This value is defined as a degree of fluidization (High Slope).

(1.3.2. Method of measuring avalanche energy change)
Similar to the fluidization degree measurement, the measurement is performed by the following procedure using the powder fluidity measurement device.
100 cm ³ of the measurement sample is sealed in a rotating drum made of glass and attached to the powder fluidity measuring device. The rotating drum is rotated at a low speed of 0.3 rpm and the avalanche phenomenon is observed 200 times. The avalanche phenomenon is recorded by a CCD camera, numerically processed, and the difference between the potential energy decrease start point and the potential energy increase start point is calculated as the change in potential energy before and after the avalanche. This value is referred to as an avalanche energy change amount (Avalanche Energy).

[2. Toner base particles]
The toner base particles according to the present invention contain a binder resin, a release agent, and a crystalline resin of a type different from the release agent.
The volume-based median diameter (D50% diameter) of the toner base particles according to the present invention is preferably in the range of 4.5 to 8.0 μm. From the viewpoint of improving the image quality, the diameter is preferably smaller, but if the particle diameter is small, the adhesive force of the toner base particles increases. For this reason, when the particle size of the toner base particles is small, the degree of fluidization tends to be low and the amount of change in avalanche energy tends to be high. However, when the particle size is 4.5 μm or more, it is possible to avoid deterioration of toner replenishability. . Further, when the thickness is 8.0 μm or less, it is possible to avoid deterioration in the image quality of the obtained output image. As described above, when the volume-based median diameter of the toner base particles is within the above range, both the image quality of the output image and the toner replenishability are satisfied, and functions such as charging, development, transfer, and cleaning are both compatible. Can be. If the particle diameter of the toner base particles is in the range of 5.0 to 6.2 μm, it is more preferable from the viewpoint of both the image quality of the output image and the toner replenishing property. Is obtained.

(Method of measuring volume-based median diameter (D50% diameter))
As a volume-based median diameter (D50% diameter) of the toner base particles, for example, “Multisizer 3 (manufactured by Beckman Coulter)” and a computer system equipped with data processing software “Software V3.51” (Beckman Coulter Can be measured and calculated in the same manner as described above, using a device connected to the product. As a measurement procedure, first, 0.02 g of the toner particles is dispersed in 20 mL of a surfactant solution and allowed to adapt. Thereafter, ultrasonic dispersion is performed for 1 minute to prepare a toner particle dispersion. As the surfactant solution, for example, a solution obtained by diluting a neutral detergent containing a surfactant component ten times with pure water may be used. This toner particle dispersion is dropped into a beaker of ISOTON II (manufactured by Beckman Coulter, Inc.) until the measured concentration becomes 5 to 10%, and the measurement is performed by setting the measuring machine count to 25,000. Here, the aperture size of the multisizer 3 is 100 μm. In the measurement, the frequency of dividing the range of 2 to 60 μm into 256 is calculated, and the particle diameter of 50% from the larger volume integral fraction is defined as the volume-based median diameter (D50% diameter) of the toner base particles. Since the external additive is usually very small compared to the toner base particles, the volume-based median diameter (D50% diameter) of the toner base particles is equal to the volume-based median diameter (D50% diameter) of the toner particles. Is treated as if

(Circularity of toner base particles)
As for the circularity of the toner base particles used in the present invention, the average circularity represented by the following formula (1) is preferably in the range of 0.920 to 1.000 from the viewpoint of toner replenishment. If the circularity of the toner base particles is within the above range, the contact points between the toner particles will be small. As a result, the external force responsiveness is improved, the degree of fluidization is increased, and the avalanche collapse is also likely to occur, that is, the amount of change in the avalanche energy is reduced, so that a toner having more excellent toner replenishability can be obtained. If the average circularity is in the range of 0.920 to 1.000, sufficient transfer efficiency can be ensured.

    Equation (1) Average circularity = (perimeter of a circle having the same projection area as the particle image) / (perimeter of the particle projection image)

  In addition, as an example of the measurement for obtaining the average circularity, a measurement using an average circularity measuring device “FPIA-2100” (manufactured by Sysmex) can be mentioned. As a specific operation, the toner base particles are wetted in an aqueous solution of a surfactant, dispersed by performing ultrasonic dispersion for 1 minute, and then using “FPIA-2100” in a measurement condition HPF (high magnification imaging) mode. The measurement is performed at an appropriate concentration of 3000 to 10,000 HPF detections.

<2.1. Binder resin>
The binder resin used in the present invention is not particularly limited, but the binder resin preferably contains a styrene-acryl resin because charge control is easy. The styrene-acrylic resin referred to here is formed by addition-polymerizing a styrene monomer which is a polymerizable monomer and a (meth) acrylate monomer. The styrene monomer includes, in addition to styrene represented by the structural formula of CH ₂ ＣＨCH—C ₆ H ₅ , a styrene structure having a known structure having a side chain or a functional group in the styrene structure. In addition, the (meth) acrylic acid ester monomer referred to herein is an acrylic acid ester or methacrylic acid ester represented by CH ₂ ＣＨCHCOOR (R is an alkyl group), as well as an acrylic acid ester derivative or a methacrylic acid ester derivative. And the like, which include known esters having side chains and functional groups. Hereinafter, specific examples of the styrene monomer and the (meth) acrylate monomer capable of forming a styrene-acrylic resin are shown, but those usable for forming the styrene-acrylic resin used in the present invention are shown below. Is not limited to the following.

  Specific examples of the styrene monomer include, for example, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene , P-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene and the like. These styrene monomers can be used alone or in combination of two or more.

Specific examples of the (meth) acrylate monomer include, for example, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, and 2-ethylhexyl acrylate. Acrylate monomers such as stearyl acrylate, lauryl acrylate, and phenyl acrylate; methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, Stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl meth Relate, methacrylic acid esters such as dimethyl aminoethyl methacrylate.
The content of the styrene-acrylic resin is preferably 70% by mass or more based on the total amount of the binder resin, and within this range, the effect of improving the chargeability can be sufficiently exhibited.

In addition, other than the above, a third polymerizable monomer can be used as the polymerizable monomer. As the third polymerizable monomer, acrylic acid, methacrylic acid, maleic anhydride, acid monomers such as vinyl acetic acid and acrylamide, methacrylamide, acrylonitrile, ethylene, propylene, butylene vinyl chloride, N-vinylpyrrolidone and Butadiene and the like.
As the polymerizable monomer, a polyfunctional vinyl monomer may be further used. Examples of the polyfunctional vinyl monomer include dimethacrylates and trimethacrylates of tertiary or higher alcohols such as diacrylates such as ethylene glycol, propylene glycol, butylene glycol, and hexylene glycol, divinylbenzene, pentaerythritol, and trimethylolpropane. And the like.

(Method for producing styrene-acrylic resin)
The styrene-acrylic resin is preferably produced by an emulsion polymerization method. Emulsion polymerization can be obtained by dispersing and polymerizing a polymerizable monomer such as styrene or acrylate in an aqueous medium described below. In order to disperse the polymerizable monomer in the aqueous medium, it is preferable to use a surfactant, and a known polymerization initiator and chain transfer agent can be used for the polymerization.

(Polymerization initiator)
As the polymerization initiator, various known polymerization initiators are suitably used. Specifically, for example, hydrogen peroxide, acetyl peroxide, cumyl peroxide, -tert-butyl peroxide, propionyl peroxide, benzoyl peroxide, chlorobenzoyl peroxide, dichlorobenzoyl peroxide, bromomethylbenzoyl peroxide, Lauroyl peroxide, ammonium persulfate, sodium persulfate, potassium persulfate, diisopropyl peroxycarbonate, di-t-butyl peroxide, tetralin hydroperoxide, 1-phenyl-2-methylpropyl-1-hydroperoxide, pertriphenylacetic acid-tert -Hyperperoxide, -tert-butylpermate, -tert-butylperacetate, -tert-butylperbenzoate, -tert-butylperphenylacetate, -tert-butylpermethoxyacetate, perN- (3-toluyl) Palmitic acid-ter Peroxides such as -butyl; 2,2'-azobis (2-aminodipropane) hydrochloride, 2,2'-azobis- (2-aminodipropane) nitrate, 1,1'-azobis (1- Azo compounds such as methyl butyronitrile-3-sulfonate), 4,4'-azobis-4-cyanovaleric acid, and poly (tetraethylene glycol-2,2'-azobisisobutyrate). .

(Chain transfer agent)
The chain transfer agent is not particularly restricted but includes, for example, mercaptans such as octyl mercaptan, dodecyl mercaptan, alkyl mercaptan, t-dodecyl mercaptan; n-octyl-3-mercaptopropionate, stearyl-3-mercaptopropione. For example, mercaptopropionic acid such as acrylate, mercapto fatty acid ester and styrene dimer can be used. These can be used alone or in combination of two or more.

<2.2. Release Agent>
A release agent can be added to the toner base particles according to the present invention. As the release agent, wax is preferably used. Examples of the wax include hydrocarbon waxes such as low-molecular-weight polyethylene wax, low-molecular-weight polypropylene wax, Fischer-Tropsch wax, microcrystalline wax, and paraffin wax, carnauba wax, pentaerythritol behenate, behenyl behenate, citrate And ester waxes such as behenyl acid. These can be used alone or in combination of two or more. In the present invention, among the above, microcrystalline wax can be suitably used.

  In addition, the microcrystalline wax is a wax mainly extracted from the residual oil of vacuum distillation of crude oil, and contains a branched hydrocarbon (isoparaffin) and a saturated cyclic hydrocarbon (cycloparaffin). Examples of the microcrystalline wax that can be preferably used in the present invention include HNP-0190, HI-MIC-1045, HI-MIC-1070, HI-MIC-1080, and HI-MIC-1090 manufactured by Nippon Seiro Co., Ltd. HI-MIC-2045, HI-MIC-2065 and HI-MIC-2095.

  Further, the melting point of the wax suitably used as the release agent is preferably from 50 to 95 [deg.] C. from the viewpoint of ensuring the low-temperature fixability and the releasability of the toner. The content ratio of the wax is preferably from 2 to 20% by mass, more preferably from 3 to 18% by mass, and still more preferably from 4 to 15% by mass based on the total amount of the binder resin.

<2.3. Crystalline resin>
(Definition and type of crystalline resin)
The crystalline resin in the present invention is not a stepwise endothermic change but a distinct endothermic peak in the differential scanning calorimetry (DSC), and is different from the release agent contained in the toner base particles. Kind of resin. The clear endothermic peak specifically refers to a peak showing a half-width of the endothermic peak within 15 ° C. when measured at a heating rate of 10 ° C./min in differential scanning calorimetry (DSC). I do. Examples of the crystalline resin include a crystalline polyester resin and a crystalline vinyl resin. The crystalline resin in the present invention preferably contains a crystalline polyester resin, particularly for realizing low-temperature fixability. The crystalline polyester resin is not particularly limited, and is a known polyester obtained by a polycondensation reaction between a divalent or higher carboxylic acid (polyhydric carboxylic acid) and a divalent or higher valent alcohol (polyhydric alcohol). Resin can be used.

  The differential scanning calorimetry (DSC) can be performed using, for example, a DSC-7 differential scanning calorimeter (manufactured by PerkinElmer) or a TAC7 / DX thermal analyzer controller (manufactured by PerkinElmer). Specifically, 4.50 mg of the sample was sealed in an aluminum pan (KIT No. 0219-0041), set in a sample holder of “DSC-7”, and an empty aluminum pan was used for reference measurement. Heat-Cool-Heat temperature control was performed at a measurement temperature of 0 to 200 ° C., a temperature rising rate of 10 ° C./min, and a temperature decreasing rate of 10 ° C./min. Get data in Heat. The melting point is the temperature at the peak top of the endothermic peak.

(Melting point of crystalline resin)
The melting point (Tm) of the crystalline resin is preferably from 50 to 95 ° C, more preferably from 55 to 85 ° C. When the melting point of the crystalline resin is in the above range, sufficient low-temperature fixability and excellent hot offset resistance can be obtained. Note that the melting point of the crystalline resin can be controlled by the composition of the resin.

  In the present invention, the melting point of a crystalline resin such as a crystalline polyester resin is a value measured as follows. That is, using a differential scanning calorimeter “Diamond DSC” (manufactured by PerkinElmer), a first temperature raising step of raising the temperature from 0 ° C. to 200 ° C. at a rate of 10 ° C./min, and 200 ° C. at a cooling rate of 10 ° C./min. The temperature is measured under measurement conditions (heating / cooling conditions) in which a cooling process of cooling from 0 ° C to 0 ° C and a second heating process of raising the temperature from 0 ° C to 200 ° C at a rate of 10 ° C / min are performed in this order. Based on the DSC curve obtained by this measurement, the endothermic peak top temperature derived from the crystalline polyester resin in the first heating process is defined as a melting point (Tm). As a measurement procedure, 3.0 mg of a measurement sample (crystalline polyester resin) is sealed in an aluminum pan and set in a diamond DSC sample holder. The reference uses an empty aluminum pan.

(Content of crystalline resin)
The content of the crystalline resin contained in the toner base particles of the present invention is preferably in the range of 1 to 30% by mass. When the content of the crystalline resin in the toner base particles is 1% by mass or more, the effect can be suitably exhibited. Further, when the content of the crystalline resin in the toner base particles is 30% by mass or less, occurrence of thermal aggregation (blocking) of the toner can be avoided.

(2.3.1. Crystalline polyester resin)
As described above, a crystalline polyester resin is a resin obtained by a polycondensation reaction between a divalent or higher carboxylic acid (polyhydric carboxylic acid) and a divalent or higher valent alcohol (polyhydric alcohol). The molecular weight of the crystalline polyester resin measured by gel permeation chromatography (GPC) is preferably 5,000 to 50,000 in weight average molecular weight (Mw) and 1500 to 25,000 in number average molecular weight (Mn). The molecular weight of the crystalline polyester resin by GPC is a value measured as follows. That is, using an apparatus “HLC-8120GPC” (manufactured by Tosoh Corporation) and a column “TSKguardcolumn + TSKgelSuperHZ-M3 consecutive units” (manufactured by Tosoh Corporation), while maintaining the column temperature at 40 ° C., tetrahydrofuran (THF) was used as a carrier solvent at a flow rate of 0. At a flow rate of 2 mL / min, the measurement sample (crystalline polyester resin) is dissolved in tetrahydrofuran so as to have a concentration of 1 mg / mL under a dissolution condition of treating at room temperature for 5 minutes using an ultrasonic disperser. A sample solution was obtained by treatment with a 2 μm membrane filter, and 10 μL of this sample solution was injected into the apparatus together with the above-mentioned carrier solvent, detected using a refractive index detector (RI detector), and the molecular weight distribution of the measurement sample was measured. Is measured using monodispersed polystyrene standard particles. It is calculated using the calibration curve obtained. Ten points are used as polystyrene for the calibration curve measurement.

(2.3.1.1. Polyvalent carboxylic acid)
The polycarboxylic acid is a compound containing two or more carboxy groups in one molecule, and an alkyl ester, an acid anhydride and an acid chloride of a polycarboxylic acid compound can be used. Specifically, for example, oxalic acid, succinic acid, maleic acid, adipic acid, β-methyl adipic acid, azelaic acid, sebacic acid, nonanedicarboxylic acid, decanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, fumaric acid, Citraconic acid, diglycolic acid, cyclohexane-3,5-diene-1,2-dicarboxylic acid, malic acid, citric acid, hexahydroterephthalic acid, malonic acid, pimelic acid, tartaric acid, mucus acid, phthalic acid, isophthalic acid, Terephthalic acid, tetrachlorophthalic acid, chlorophthalic acid, nitrophthalic acid, p-carboxyphenylacetic acid, p-phenylene diacetic acid, m-phenylenediglycolic acid, p-phenylenediglycolic acid, o-phenylenediglycolic acid, diphenylacetic acid, Diphenyl-p, p'-dicarboxylic acid, naphtha Dicarboxylic acids such as 1,4-dicarboxylic acid, naphthalene-1,5-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, anthracenedicarboxylic acid and dodecenylsuccinic acid; trimellitic acid, pyromellitic acid, naphthalene You may combine with trivalent or more carboxylic acids, such as tricarboxylic acid, naphthalene tetracarboxylic acid, pyrene tricarboxylic acid, and pyrene tetracarboxylic acid. In the present invention, the polyvalent carboxylic acid forming the crystalline polyester resin is preferably an aliphatic polycarboxylic acid.

(2.3.1.2. Polyhydric alcohol)
Polyhydric alcohols are compounds containing two or more hydroxy groups in one molecule. Specifically, for example, ethylene glycol, propylene glycol, butanediol, diethylene glycol, hexanediol, cyclohexanediol, octanediol, decanediol, 1,12-dodecanediol, an ethylene oxide adduct of bisphenol A, a propylene oxide of bisphenol A Dihydric alcohols such as adducts; trihydric or higher polyols such as glycerin, pentaerythritol, hexamethylolmelamine, hexaethylolmelamine, tetramethylolbenzoguanamine, tetraethylolbenzoguanamine and the like. In the present invention, the polyhydric alcohol forming the crystalline polyester resin is preferably an aliphatic polyhydric alcohol.

(2.3.2. Hybrid crystalline polyester resin)
The crystalline polyester resin is more preferably a hybrid crystalline polyester resin (hereinafter, also referred to as “hybrid resin”) in which an amorphous resin segment and a crystalline polyester segment are chemically bonded. By hybridizing the crystalline polyester resin, the affinity with the amorphous resin in the binder resin can be increased, and the crystalline polyester resin is more easily included in the binder resin. By moving the crystalline polyester resin having high hygroscopicity away from the surface of the toner base particles, the hygroscopicity of the toner can be suppressed, the adhesive force between the toner base particles can be reduced, and the toner replenishing property can be further improved.
It is preferable that the amorphous resin segment is composed of the same kind of resin as the amorphous resin contained in the binder resin. By hybridizing in such a form, the affinity between the crystalline polyester resin and the binder resin is increased, and the hybrid resin is more easily taken into the amorphous resin. As a result, since the crystalline polyester resin segment having high hygroscopicity is present inside the toner base particles, the adhesion between the toner base particles is prevented from increasing due to the moisture absorption, and the toner replenishing property is further improved.
Here, “the same type of resin” means that a characteristic chemical bond is commonly contained in the repeating unit. The “characteristic chemical bond” is defined in the NIMS substance / material database (http://polymer.nims.go.jp/PoLyInfo/guide/jp/term_polymer.html). Follow "Polymer classification". That is, polyacryl, polyamide, polyanhydride, polycarbonate, polydiene, polyester, polyhaloolefin, polyimide, polyimine, polyketone, polyolefin, polyether, polyphenylene, polyphosphazene, polysiloxane, polystyrene, polysulfide, polysulfone, polyurethane, polyurea , Polyvinyl and other polymers are referred to as “characteristic chemical bonds”.

(2.3.2.1. Amorphous resin segment)
As the amorphous resin segment constituting the hybrid resin, a known monomer constituting the amorphous resin such as a vinyl resin can be used. As a specific example, the above-mentioned polymerizable monomer constituting the styrene-acrylic resin can be similarly used. The content of the amorphous resin segment in the hybrid resin is preferably in the range of 5 to 30% by mass.

(2.3.2.2. Crystalline polyester segment)
The crystalline polyester segment constituting the hybrid resin is composed of a crystalline polyester resin produced by performing a polycondensation reaction between a polycarboxylic acid and a polyhydric alcohol in the presence of a catalyst. Here, since the specific types of the polyhydric carboxylic acid and the polyhydric alcohol are as described above, the detailed description is omitted here.

(2.3.2.3. Bi-reactive monomer)
The crystalline resin formed by bonding the amorphous resin segment and the crystalline polyester segment is preferably bonded by a bi-reactive monomer.
“Bi-reactive monomer” is a monomer that binds a crystalline polyester segment and an amorphous resin segment. Specifically, for example, a group selected from a hydroxy group, a carboxy group, an epoxy group, a primary amino group and a secondary amino group that form a crystalline polyester segment and an amorphous resin segment are included in the molecule. A monomer having both an ethylenically unsaturated group to be formed and preferably a monomer having both a hydroxy group or a carboxy group and an ethylenically unsaturated group is preferable. More preferably, it is a monomer having both a carboxy group and an ethylenically unsaturated group. That is, it is preferably a vinyl carboxylic acid.

  Specific examples of the bi-reactive monomer include, for example, acrylic acid, methacrylic acid, fumaric acid, maleic acid, and the like, and further include esters of these hydroxyalkyls (1 to 3 carbon atoms). However, acrylic acid, methacrylic acid and fumaric acid are preferred from the viewpoint of reactivity. The crystalline polyester segment and the amorphous resin segment are bonded via the bi-reactive monomer.

  From the viewpoint of improving the low-temperature fixability, high-temperature offset resistance and durability of the toner, the amount of the amphoteric monomer is used based on 100 parts by mass of the total amount of the polymerizable monomers constituting the amorphous resin segment. Is preferably 1 to 10 parts by mass, more preferably 4 to 8 parts by mass.

(2.3.2.4. Method for producing hybrid resin)
As a method for producing the hybrid resin, an existing general scheme can be used. The following three are typical methods.
(1) A crystalline polyester segment is polymerized in advance, a bi-reactive monomer is allowed to react with the crystalline polyester segment, and a polymerizable monomer for forming an amorphous resin segment and (meth) A) A method of forming a hybrid resin by reacting an acrylate monomer.
(2) Amorphous resin segments are polymerized in advance, a polyfunctional carboxylic acid and a polyvalent carboxylic acid for forming a crystalline polyester segment by reacting a bi-reactive monomer with the amorphous resin segments. A method of forming a crystalline polyester segment by reacting an alcohol.
(3) A method of preliminarily polymerizing a crystalline polyester segment and an amorphous resin segment, and reacting them with a bi-reactive monomer to bond them.

In the present invention, any of the above production methods can be used, but the method of the above item (2) is preferable.
Specifically, a polyvalent carboxylic acid and a polyhydric alcohol forming a crystalline polyester segment, and a polymerizable monomer and a bi-reactive monomer forming an amorphous resin segment are mixed, and a polymerization initiator is mixed. In addition, it is preferable that the polycondensation reaction is carried out by adding an esterification catalyst after the addition of the polymerizable monomer and the bi-reactive monomer to form an amorphous resin segment.

  Here, as a catalyst for synthesizing the crystalline polyester segment, various conventionally known catalysts can be used. Examples of the esterification catalyst include tin compounds such as dibutyltin oxide and tin (II) 2-ethylhexanoate, and titanium compounds such as titanium diisopropylate bistriethanolamine. Examples of the esterification promoter include gallic acid. Acids and the like. The amount of the esterification catalyst used is preferably 0.01 to 1.5 parts by mass with respect to 100 parts by mass of the total amount of the polyhydric alcohol compound, the polycarboxylic acid compound and the bireactive monomer component, and is preferably 0.1 to 1.5 parts by mass. -1.0 parts by mass is more preferred. The amount of the esterification cocatalyst to be used is preferably 0.001 to 0.5 parts by mass, more preferably 0.001 to 0.5 parts by mass, based on 100 parts by mass of the total of the polyhydric alcohol compound, the polycarboxylic acid compound and the bireactive monomer component. 01 to 0.1 part by mass is more preferred.

<2.4. Method for producing toner (base) particles>
The toner base particles according to the present invention contain a binder resin, a release agent, and a crystalline resin, and contain a colorant and other internal additives as necessary. The production method is not particularly limited, but an emulsion aggregation method is preferred. According to the emulsion aggregation method, toner base particles having a sharp particle size distribution and a highly controlled particle size can be obtained.

An example of the method for producing toner particles by the emulsion aggregation method of the present invention is described below.
(1) Step of preparing a dispersion in which colorant fine particles are dispersed in an aqueous medium (2) Dispersion in which binder resin fine particles containing an internal additive as necessary are dispersed in an aqueous medium (3) A step of mixing a dispersion of colorant fine particles and a dispersion of binder resin fine particles to form toner particles by aggregating, associating, and fusing the colorant fine particles and the binder resin fine particles. (4) A step of filtering the toner particles from a dispersion system (aqueous medium) of the toner particles to remove a surfactant and the like (5) A step of drying the toner particles (6) A step of adding an external additive to the toner particles

(Coagulant)
The flocculant used in the present invention is not particularly limited, but those selected from metal salts are preferably used. For example, salts of monovalent metals such as salts of alkali metals such as sodium, potassium and lithium, salts of divalent metals such as calcium, magnesium, manganese and copper, and salts of trivalent metals such as iron and aluminum And the like, as specific salts, sodium chloride, potassium chloride, lithium chloride, calcium chloride, magnesium chloride, zinc chloride, copper sulfate, magnesium sulfate, manganese sulfate, etc., among these, especially Preferred are salts of divalent metals. When a salt of a divalent metal is used, aggregation can be promoted with a smaller amount. These may be used alone or in combination of two or more.

(Core / shell structure)
Note that the method for producing toner particles by the emulsion aggregation method is suitable for producing toner base particles having a core-shell structure, and it is more preferable that the toner base particles according to the present invention have a core-shell structure. To give an example of producing toner base particles having a core-shell structure, first, binder resin particles for core particles and colorant particles are aggregated, associated, and fused to produce core particles. Subsequently, the binder resin fine particles for the shell layer are added to the dispersion liquid of the core particles, and the shell resin particles for the shell layer are aggregated and fused on the surface of the core particles to form a shell layer covering the surface of the core particles. It can be obtained by forming.

[3. Other internal additives]
<3.1. Colorant>
As the colorant contained in the toner base particles according to the present invention, a known inorganic or organic colorant can be used. As the colorant, various organic and inorganic pigments and dyes can be used in addition to carbon black and magnetic powder. The amount of the coloring agent is in the range of 1 to 30% by mass, preferably 2 to 20% by mass, based on the toner particles.

<3.2. Charge control agent>
A charge controlling agent can be added to the toner base particles according to the present invention as needed. For example, various known charge control agents can be used. As the charge control agent, various known compounds that can be dispersed in an aqueous medium can be used. Specifically, nigrosine dyes, metal salts of naphthenic acid or higher fatty acids, alkoxylated amines, Quaternary ammonium salt compounds, azo metal complexes, salicylic acid metal salts or metal complexes thereof, and the like. The content ratio of the charge control agent is preferably from 0.1 to 10% by mass, more preferably from 0.5 to 5% by mass, based on the total amount of the binder resin.

[4. External additive]
The external additive is attached to the surface of the toner base particles.
As the external additive of the toner for developing an electrostatic image according to the present invention, known inorganic fine particles, organic fine particles, and a lubricant can be used. One or more external additives may be used, and it is particularly preferable to use two or more external additives having different particle diameters. If the particle diameter is different, the role as an external additive is different.In general, the larger the diameter, the more the spacer effect is exerted to reduce the adhesive force between the toner base particles, and the smaller the diameter, the more the surface of the toner base particles is coated. Easy to raise the fluidity. Regarding the shape, not only a spherical external additive, but also an acicular shape represented by rutile-type titanium oxide particles, an irregular shape, a spindle shape, a confetti-like shape, and the like can be used without limitation.

  From the external additives as described above, by selecting an appropriate particle size and shape and externally adding an appropriate number of copies, it is possible to adjust the fluidization degree and the avalanche energy change amount of the toner to desired values. It is possible.

<4.1. Types of external additives>
Examples of the inorganic fine particles include silica particles, titanium oxide particles, alumina particles, zirconia particles, zinc oxide particles, chromium oxide particles, cerium oxide particles, antimony oxide particles, tungsten oxide particles, tin oxide particles, tellurium oxide particles, oxidized particles. Manganese particles and boron oxide particles are included. Preferred examples include silica particles, titanium oxide particles, alumina particles, and strontium titanate particles. The surface of the inorganic fine particles is preferably subjected to a hydrophobic treatment, and a known surface treating agent is used for the hydrophobic treatment. The surface treatment agent may be one or more types. The collar includes a silane coupling agent, a silicone oil, a titanate coupling agent, an aluminate coupling agent, a fatty acid, a fatty acid metal salt, an esterified product thereof, and the like. Rosin acid is included.

Examples of the silane coupling agent include dimethyldimethoxysilane, hexamethyldisilazane (HMDS), methyltrimethoxysilane, isobutyltrimethoxysilane, and decyltrimethoxysilane. Examples of the silicone oil include a cyclic compound, a linear or branched organosiloxane, and more specifically, an organosiloxane oligomer, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, tetramethyl Cyclotetrasiloxane and tetravinyltetramethylcyclotetrasiloxane.
The organic fine particles include spherical organic fine particles having a number average primary particle diameter of about 10 to 2000 nm. Specifically, organic fine particles of a homopolymer such as styrene or methyl methacrylate or a copolymer thereof can be used.

  The lubricating material is used for the purpose of further improving the cleaning property and the transferring property. Examples of the lubricating material include salts of zinc, stearic acid, aluminum, copper, magnesium, calcium and the like, and zinc of oleic acid. Higher fatty acids such as salts of manganese, iron, copper, magnesium, etc., salts of zinc, copper, magnesium, calcium, etc. of palmitic acid, salts of zinc, calcium, etc. of linoleic acid, salts of zinc, calcium, etc. of ricinoleic acid Metal salts.

(4.1.1. Titanium oxide particles)
As the external additive, the average aspect ratio (number average major axis / number average minor axis) derived from the ratio of the number average major axis to the number average minor axis is in the range of 2 to 15, more preferably in the range of 5 to 13. Is preferably contained in the range of 0.10 to 0.80 parts by mass with respect to the toner base particles. In addition, “containing in the range of 0.10 to 0.80 parts by mass with respect to the toner base particles” means that 0.10 to 0.10 parts by mass of the total toner base particles contained in the electrostatic image developing toner. It means that it is contained within the range of 0.80 parts by mass.

  Here, when the spacer effect of the external additive is too high, the volume shrinkage of the toner hardly occurs, so that it becomes difficult to pass the toner through a narrow path such as when the toner is discharged from a storage container (toner bottle). However, the surface of the toner base particles needs to be coated to some extent with an external additive from the viewpoints related to the electrophotographic process such as control of charging ability including fluidity. By using the titanium oxide particles having a high aspect ratio within the range of 2 to 15 as described above as an external additive, it is possible to increase the coverage of the toner base particles with the external additive and to prevent an excessive spacer effect from being imparted. As a result, it is possible to secure the toner discharging property while improving the fluidity and the charging property. Further, since the contact area with the toner base particles is larger than that of other external additives, the toner is hardly detached from the toner, and the toner replenishing property can be maintained.

  Further, the titanium oxide particles preferably have a rutile-type crystal structure. Rutile-type titanium oxide has a higher calcination temperature and fewer surface hydroxyl groups than anatase-type titanium oxide. From this, it is possible to prevent an increase in the adhesive force between the toner base particles due to the adsorption of moisture, and thus it is possible to further improve the transportability and dischargeability of the toner.

  The titanium oxide particles are preferably subjected to a hydrophobic treatment. A known surface treatment agent (coupling agent) can be used for the hydrophobization treatment, but octyltrimethoxysilane is more preferably used. The titanium oxide particles hydrophobized by octyltrimethoxysilane are covered with a straight carbon chain having 8 carbon atoms, and are ideally fixed to the surface of the toner base particles. Therefore, the titanium oxide particles uniformly exist on the surface of the toner base particle without moving and locally distributing on the surface of the toner base particle. For this reason, the fluidization degree and the avalanche energy change amount of the toner can be set to desirable values as powder. Further, by being sufficiently fixed to the toner base particles, detachment from the toner base particles due to external physical impact is reduced. For this reason, long-term stable powder characteristics can be imparted to the toner base particles. The coupling agent is preferably a straight-chain coupling agent having 6 to 10 carbon atoms. If the coupling agent has 6 or more carbon atoms, the carbon chain length is sufficient to stably immobilize the toner base particles. In addition, if the coupling agent is a straight-chain coupling agent having 10 or less carbon atoms, the carbon chain length does not become too bulky and can prevent the progress of the coupling reaction with the titanium oxide particles from being prevented. The titanium oxide particles can be covered with a surface modifying group. In addition, examples of the above-mentioned known surface treatment agents include dimethyldimethoxysilane, hexamethyldisilazane (HMDS), methyltrimethoxysilane, and isobutyltrimethoxysilane.

(Calculation of average aspect ratio)
The average aspect ratio of the titanium oxide particles is determined as “number average major axis / number average minor axis” using the number average major axis and the number average minor axis. The number-average major axis and the number-average minor axis are, for example, about 20 titanium oxide particles randomly extracted in an electron micrograph using a scanning electron microscope (SEM) “JEM-7401F” (manufactured by JEOL Ltd.). The number average major axis and the number average minor axis are measured, respectively, and the average value of the 20 titanium oxide particles can be obtained.

(4.1.2. Spherical silica particles)
As the external additive, it is preferable to use one or more kinds of spherical silica particles having a number average particle diameter in a range of 60 to 130 nm, more preferably in a range of 80 to 100 nm. Such spherical silica particles are preferably contained in a range of 0.05 to 0.80 parts by mass based on the toner base particles. In addition, “including in the range of 0.05 to 0.80 parts by mass with respect to the toner base particles” means that 0.05 to 0.8 parts by mass of the total toner base particles contained in the toner for developing an electrostatic image. It means that it is contained within the range of 0.80 parts by mass.

  Spherical silica particles having a number average particle diameter of 60 to 130 nm can achieve both a sufficient spacer effect and the difficulty of detachment from the toner base particles, so that the fluidization degree and the avalanche energy change can be improved simultaneously. Easy. As a method for producing the spherical silica particles, a known method can be used, but it is more preferable that the particles are produced by a sol-gel method. One of the features of the spherical silica particles produced by the sol-gel method is that the particle size distribution is narrow, which allows the fluidity of the toner to be more precisely controlled. In addition, the number average particle diameter of the external additive is, for example, 20 spherical silica extracted at random in an electron micrograph using a scanning electron microscope (SEM) “JEM-7401F” (manufactured by JEOL Ltd.). The particle diameter of each particle is measured, and the average value of the 20 spherical silica particles can be obtained.

The larger the value of the degree of sphericity of the spherical silica particles, the more effective the toner replenishment is. As the external additive has a higher degree of sphericity and is closer to a perfect circle, the phenomenon in which the toner acts like an intermeshing gear and aggregates can be suppressed. Here, the sphericity refers to the true sphericity of Wadell, and is represented by the following equation (2).
Formula (2) Degree of sphericity = (surface area of sphere having the same volume as actual particle) / (surface area of actual particle)
The “surface area of a sphere having the same volume as the actual particles” can be obtained by arithmetic calculation from the volume average particle diameter. The “actual surface area of the particles” can be substituted with the BET specific surface area obtained by using “powder specific surface area measuring device SS-100” (manufactured by Shimadzu Corporation).

二 Two-component developer for electrostatic image development≫
The two-component developer for developing an electrostatic image according to the present invention contains the toner for developing an electrostatic image of the present invention and carrier particles.
The two-component developer is prepared by appropriately mixing the toner particles and the carrier particles such that the content (toner concentration) of the toner particles is in the range of 4.0 to 8.0% by mass. A component developer can be constituted. Examples of the mixing device used for the mixing include a Nauta mixer, a W cone, and a V-type mixer.

[1. Carrier particles]
The carrier particles according to the present invention are made of a magnetic material. Examples of the carrier particles include core particles made of the magnetic material and a coating type carrier particle having a coating material layer covering the surface thereof, and a resin dispersion in which a fine powder of the magnetic material is dispersed in a resin. Type of carrier particles. The carrier particles are preferably coated carrier particles from the viewpoint of suppressing adhesion of the carrier particles to the photoconductor.

<1.1. Core particles>
The core particles are composed of a magnetic material, for example, a substance that is strongly magnetized in the direction by a magnetic field. The magnetic substance may be one or more kinds, and examples thereof include iron, nickel, and cobalt, which exhibit ferromagnetism, alloys or compounds containing these metals, and alloys, which exhibit ferromagnetism by heat treatment, Is included.
Examples of the metal having ferromagnetism or a compound containing the same include iron, ferrite represented by the following formula (a), and magnetite represented by the following formula (b). M in the formulas (a) and (b) represents one or more monovalent or divalent metals selected from the group consisting of Mn, Fe, Ni, Co, Cu, Mg, Zn, Cd and Li.
Formula (a): MO.Fe ₂ O ₃
Formula (b): MFe ₂ O ₄
Examples of alloys that exhibit ferromagnetism by the heat treatment include Heusler alloys such as manganese-copper-aluminum and manganese-copper-tin, and chromium dioxide.
The core particles are preferably various ferrites. This is because the specific gravity of the coated carrier particles is smaller than the specific gravity of the metal constituting the core particles, so that the impact force of stirring in the developing device can be further reduced.

<1.2. Coating material>
As the coating material, a known resin used for coating core particles of carrier particles can be used. The coating material is preferably a resin having a cycloalkyl group, from the viewpoint of reducing the hygroscopicity of the carrier particles and increasing the adhesion of the coating layer to the core material particles. Examples of the cycloalkyl group include a cyclohexyl group, a cyclopentyl group, a cyclopropyl group, a cyclobutyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, and a cyclodecyl group. Among them, a cyclohexyl group or a cyclopentyl group is preferable, and a cyclohexyl group is more preferable from the viewpoint of adhesion between the coating layer and the ferrite particles. The weight average molecular weight Mw of the resin is, for example, 10,000 to 800,000, and more preferably 100,000 to 750,000. The content of the cycloalkyl group in the resin is, for example, 10 to 90% by mass. The content of the cycloalkyl group in the resin can be determined by, for example, pyrolysis-gas chromatography / mass spectrometry (P-GC / MS) or ¹ H-NMR.

  The embodiment to which the present invention can be applied is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist of the present invention.

  Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto. In the examples, “parts” or “%” is used, but “parts by mass” or “% by mass” is used unless otherwise specified.

<< Preparation of Toner Base Particles 1 to 5 >>
<Preparation of colorant fine particle dispersion liquid [1]>
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. Next, by performing a dispersion process using a stirrer “CLEARMIX W MOTION CLM-0.8” (manufactured by M Technique Co., Ltd.), a colorant fine particle dispersion having a volume-based median diameter of 126 nm [1] Was prepared.

<Preparation of styrene-acrylic resin particle dispersion [1]>
(First stage polymerization)
A reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introduction device was charged with 4 parts by mass of sodium polyoxyethylene (2) dodecyl ether sulfate and 3000 parts by mass of ion-exchanged water, and stirred at 230 rpm under a nitrogen stream. While stirring, the internal temperature was raised to 80 ° C. After the temperature was raised, a solution prepared by dissolving 10 parts by mass of potassium persulfate in 200 parts by mass of ion-exchanged water was added, and the solution temperature was set to 75 ° C.
-584 parts by mass of styrene-160 parts by mass of n-butyl acrylate-After dripping a monomer mixture composed of 56 parts by mass of methacrylic acid over 1 hour, polymerization is performed while heating and stirring at 75 ° C for 2 hours. Thus, a dispersion of styrene-acrylic resin fine particles [1] was prepared.

(Second stage polymerization)
A solution prepared by dissolving 2 parts by mass of polyoxyethylene (2) sodium dodecyl ether sulfate in 3000 parts by mass of ion-exchanged water was charged into a reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introducing device. After heating, 42 parts by mass (in terms of solid content) of the above styrene-acrylic resin fine particles [1] and 70 parts by mass of microcrystalline wax “HNP-0190” (manufactured by Nippon Seiro Co., Ltd.)
239 parts by mass of styrene 111 parts by mass of n-butyl acrylate 26 parts by mass of methacrylic acid A solution prepared by dissolving a monomer solution composed of 3 parts by mass of n-octyl mercaptan at 80 ° C. is added, and a circulation route is added. The dispersion liquid containing emulsified particles (oil droplets) was prepared by mixing and dispersing for 1 hour using a mechanical disperser “CLEARMIX” (manufactured by M Technique Co., Ltd.).

  Next, an initiator solution obtained by dissolving 5 parts by mass of potassium persulfate in 100 parts by mass of ion-exchanged water is added to the dispersion, and the system is heated and stirred at 80 ° C. for 1 hour to perform polymerization. , A dispersion of styrene-acrylic resin fine particles [2] was prepared.

(3rd stage polymerization)
To the dispersion of the styrene-acrylic resin fine particles [2], a solution obtained by dissolving 10 parts by mass of potassium persulfate in 200 parts by mass of ion-exchanged water was added.
380 parts by mass of styrene 132 parts by mass of n-butyl acrylate 39 parts by mass of methacrylic acid A monomer mixture solution consisting of 6 parts by mass of n-octylmercaptan was dropped over 1 hour. After the completion of the dropwise addition, polymerization was carried out by heating and stirring for 2 hours, and then the mixture was cooled to 28 ° C. to obtain a styrene-acryl resin particle dispersion liquid [1].

<Preparation of crystalline resin particle dispersion liquid [1]>
(Synthesis of crystalline resin particles [1])
As materials for the crystalline polyester segment, 220 parts by mass of polybasic carboxylic acid compound sebacic acid (molecular weight 202.25) and 298 parts by mass of polyhydric alcohol compound 1,12-dodecanediol (molecular weight 202.33) were mixed with nitrogen. The mixture was placed in a reaction vessel equipped with an introduction tube, a dehydration tube, a stirrer, and a thermocouple and heated to 160 ° C. to dissolve. Thereafter, 2.5 parts by mass of tin (II) 2-ethylhexanoate and 0.2 parts by mass of gallic acid were added, the temperature was raised to 210 ° C., and the reaction was carried out for 8 hours. The reaction was further performed at 8.3 kPa for 1 hour to obtain a crystalline resin [1].

  Using a differential scanning calorimeter “Diamond DSC” (manufactured by PerkinElmer Co., Ltd.), the obtained crystalline resin [1] was used to acquire a DSC curve at a heating rate of 10 ° C./min. The measurement result of the melting point (Tm) by the method of measuring the endothermic peak top temperature is 82.8 ° C. Also, as a result of measuring the molecular weight by GPC “HLC-8120GPC” (manufactured by Tosoh Corporation), Mw in terms of standard styrene is 28,000.

(Preparation of crystalline resin particle dispersion liquid [1])
The above crystalline resin [1] was dissolved in 100 parts by mass and 400 parts by mass of ethyl acetate. Next, 25 parts by mass of a 5.0% by mass aqueous sodium hydroxide solution was added to prepare a resin solution. This resin solution was put into a container having a stirrer, and 638 parts by mass of a 0.26% by mass aqueous solution of sodium lauryl sulfate was dropped and mixed over 30 minutes while stirring the resin solution. During the dropping of the aqueous solution of sodium lauryl sulfate, the liquid in the reaction vessel became cloudy. Further, after the entire amount of the aqueous solution of sodium lauryl sulfate was dropped, an emulsion was prepared in which the resin solution particles were uniformly dispersed. Next, the above-mentioned emulsion was heated to 40 ° C., and ethyl acetate was distilled off under a reduced pressure of 150 hPa using a diaphragm type vacuum pump “V-700” (manufactured by BUCHI) to obtain a crystalline polyester resin. A crystalline resin particle dispersion liquid [1] was obtained.

<Preparation of crystalline resin particle dispersion liquid [2] composed of hybrid resin>
(Synthesis of crystalline resin [2] composed of hybrid resin)
220 parts of sebacic acid (molecular weight 202.25) as a polyvalent carboxylic acid compound and 298 parts of 1,12-dodecanediol (molecular weight 202.33) as a polyhydric alcohol compound, which are materials of the crystalline polyester segment, The mixture was placed in a reaction vessel equipped with an introduction tube, a dehydration tube, a stirrer, and a thermocouple and heated to 160 ° C. to dissolve. On the other hand, a solution of 46 parts of styrene, 12 parts of n-butyl acrylate, 4 parts of dicumyl peroxide, and 3 parts of acrylic acid as a bi-reactive monomer, which is a material of the previously mixed amorphous resin segment, is added dropwise. For 1 hour. Stirring was continued for 1 hour while maintaining the temperature at 170 ° C. to polymerize styrene, n-butyl acrylate and acrylic acid, and then 2.5 parts of tin (II) 2-ethylhexanoate and 0.2 part of gallic acid were added. The temperature was raised to 210 ° C., and the reaction was carried out for 8 hours. The reaction was further performed at 8.3 kPa for 1 hour to obtain a crystalline resin [2] composed of a hybrid crystalline polyester resin.

(Preparation of crystalline resin fine particle dispersion liquid [2])
100 parts of the above crystalline resin [2] was dissolved in 400 parts of ethyl acetate. Next, 25 parts of a 5.0% aqueous sodium hydroxide solution was added to prepare a crystalline resin solution. This crystalline resin solution was charged into a vessel having a stirrer and, while stirring, 638 parts of a 0.26% aqueous sodium lauryl sulfate solution was dropped and mixed over 30 minutes. During the dropping of the aqueous solution of sodium lauryl sulfate, the liquid in the reaction vessel became cloudy, and after the entire amount of the aqueous solution of sodium lauryl sulfate was added dropwise, an emulsion was prepared in which fine particles of the crystalline resin [2] were uniformly dispersed. Next, the above emulsion was heated to 40 ° C., and ethyl acetate was distilled off under a reduced pressure of 150 hPa using a diaphragm vacuum pump “V-700” (manufactured by BUCHI) to obtain a hybrid crystalline resin. A crystalline resin fine particle dispersion liquid [2] was obtained.

[Preparation of Toner Base Particles [1]]
(Aggregation / fusion process)
In a reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introduction device, 300 parts by mass (in terms of solid content) of a dispersion of styrene-acrylic resin particle dispersion [1] and a dispersion of crystalline resin fine particles [1] 60 parts by mass (in terms of solids), 1100 parts by mass of ion-exchanged water, and 40 parts by mass (in terms of solids) of a colorant fine particle dispersion [1] were prepared, and the liquid temperature was adjusted to 30 ° C. Thereafter, the pH was adjusted to 10 by adding a 5N aqueous sodium hydroxide solution. 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. After the temperature was maintained for 3 minutes, the temperature was raised, the temperature of the system was raised to 85 ° C. over 60 minutes, and the particles were aggregated while maintaining the temperature at 85 ° C. to continue the particle growth reaction. In this state, the particle size of the aggregated particles was measured with a “Coulter Multisizer 3” (manufactured by Beckman Coulter, Inc.), and when the volume-based median diameter became 6.5 μm, 40 parts by mass of sodium chloride was ion-exchanged. An aqueous solution dissolved in 160 parts by mass of water is added to stop the particle growth, and further, as a ripening step, the mixture is heated and stirred at a liquid temperature of 80 ° C. for 1 hour to promote the fusion between the particles. A dispersion of the base particles [1] was prepared.

(Washing / drying process)
The resulting dispersion liquid of the toner base particles [1] is solid-liquid separated by a basket type centrifugal separator “MARKIII Model No. 60 × 40 + M” (manufactured by Matsumoto Kikai Co., Ltd.) to form a wet cake of the toner base particles [1]. did. The wet cake is washed with ion-exchanged water at 40 ° C. in the basket type centrifuge until the electric conductivity of the filtrate becomes 5 μS / cm, and then transferred to a “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.). By drying until the water content became 0.5% by mass, toner base particles [1] were produced.

  The content of the crystalline resin in the toner base particles [1] obtained by the above method is 15% by mass, and this value can be calculated by the following equation (3). The mass of each material is a value converted into a solid content.

  Formula (3) Mass of crystalline resin / (mass of styrene-acrylic resin + mass of crystalline resin + mass of colorant) × 100 (%)

  Similarly, the styrene-acrylic resin content (% by mass) is calculated by the following equation (4). The mass of each material is a value converted into a solid content.

  Formula (4) Mass of styrene-acrylic resin / (mass of styrene-acrylic resin + mass of crystalline resin + mass of colorant) × 100 (%)

For example, in the case of the toner base particles [1], the crystalline resin content is
60 / (300 + 60 + 40) × 100 = 15%
Becomes
Styrene-acrylic resin content,
300 / (300 + 60 + 40) × 100 = 75%
, Respectively.

[Production of Toner Base Particles [2], [3] and [5]]
The production is advanced to the aggregation / fusion step in the same procedure as the toner base particles [1], and by appropriately changing the time of 85 ° C. holding state for promoting the particle growth reaction, the toner base particles [1] Can obtain toner base particles [2], [3] and [5] having different particle diameters. When the particle size of the aggregated particles was measured using “Coulter Multisizer 3” (manufactured by Beckman Coulter, Inc.), the volume-based median diameter was 7.5 μm for the toner base particles [2] and 5.5 for the toner base particles [3]. 8 μm, and 8.5 μm for the toner base particles [5]. After the growth is stopped by adding an aqueous solution of sodium chloride, the washing and drying steps are performed in the same manner as the method for producing the toner base particles [1].

[Preparation of Toner Base Particles [4]]
The same procedure as for the toner base particles [1] was used to prepare a crystalline resin particle dispersion [2] to be used, thereby obtaining toner base particles [4]. When the particle size of the aggregated particles was measured by “Coulter Multisizer 3” (manufactured by Beckman Coulter, Inc.), the volume-based median diameter was 6.4 μm.

  Table 1 shows the particle diameter, composition, and the like of the toner base particles [1] to [5].

<< Preparation of spherical silica particles >>
[Production of spherical silica particles [1]]
(1) 630 parts by mass of methanol and 90 parts by mass of water were added to a 3 L reactor equipped with a stirrer, a dropping funnel and a thermometer and mixed. While stirring this solution, 1100 parts by mass of tetramethoxysilane was hydrolyzed to obtain a suspension of silica particles. Then, the mixture was heated to 60 to 70 ° C., and 390 parts of methanol was distilled off to obtain an aqueous suspension of silica particles.
(2) 12 parts by mass of methyltrimethoxysilane was added dropwise to the aqueous suspension at room temperature to perform a hydrophobic treatment on the surface of the silica particles.
(3) After adding 1300 parts by mass of methyl isobutyl ketone to the dispersion thus obtained, the mixture was heated to 80 ° C. to distill off methanol water. 300 parts by mass of hexamethyldisilazane was added to the obtained dispersion at room temperature, and the mixture was 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 spherical silica particles [1].
When the obtained spherical silica particles [1] were observed for 20 particles using a scanning electron microscope (SEM) “JEM-7401F” (manufactured by JEOL Ltd.), the number average primary particle size was 82.0 nm. there were.

[Production of spherical silica particles [2], [3], [4] and [5]]
By appropriately changing the heating temperature and the reaction time for promoting the particle growth reaction in the same procedure as the spherical silica particles [1], the spherical silica particles [2] having a different particle diameter from the spherical silica particles [1], [3], [4] and [5] can be obtained. Similarly, the number average primary particle size was measured. The number average primary particle size was as shown in Table 2.

<< Production of titanium oxide particles >>
In this example, titanium oxide particles were produced as follows with reference to the method for producing acicular titanium oxide fine particles described in JP-A-2004-315356.
(1) 700 parts by mass of methanol was stirred in a 3 L reactor equipped with a stirrer, a dropping funnel, and a thermometer, 450 parts by mass of titanium isopropoxide was added dropwise, and stirring was continued for 3 minutes. Thereafter, the resulting titanium oxide particles were separated and collected by a centrifugal separator, and dried under reduced pressure to obtain amorphous titanium oxide.
(2) The obtained amorphous titanium oxide was heated in the air at 800 ° C. for 5 hours in a high-temperature electric furnace to obtain rutile-type titanium oxide particles.
(3) 500 g of the obtained rutile-type titanium oxide particles and 15 parts by mass of octyltrimethoxysilane were added to a 3 L reactor equipped with the above-described stirrer, dropping funnel, and thermometer, and stirred in 2 L of toluene for 10 hours. And a hydrophobic treatment. Thereafter, the reaction product was centrifuged to wash the reaction solvent, then collected by centrifugation again, and dried under reduced pressure to obtain titanium oxide particles.

  Observation of 20 particles of the obtained titanium oxide particles using a scanning electron microscope (SEM) “JEM-7401F” (manufactured by JEOL Ltd.) revealed that the number average minor axis was 6.2 nm and the number average major axis was 46. Rutile titanium oxide particles having a thickness of 0 nm and an average aspect ratio of 7.4 were obtained.

<< Preparation of Toners [1] to [22] >>
[Preparation of Toner [1]]
According to the formulation described in Table 3, 1 kg of the toner base particles [1], 0.50 parts by mass of spherical silica particles, and 0.30 parts by mass of titanium oxide particles were mixed with a Henschel mixer type “FM20C / I” (Nippon Coke Industries, Ltd.). The mixture was stirred for 20 minutes while setting the rotation speed of the stirring blade such that the peripheral speed of the blade tip became 40 m / s, thereby producing toner [1]. In addition, the temperature of the mixed powder at the time of mixing the external additive was set to be 40 ° C. ± 1 ° C.

[Production of Toners [2] to [22]]
In the production of the toner [1], the toner base particles were changed to [1] to [5] according to the prescription described in Table 3, and the number of parts by mass of the external additive was adjusted to obtain a fluidization degree and an avalanche energy. Toners [2] to [22] having different amounts of change were produced in the same procedure.
The adjustment of the number of added spherical silica particles and titanium oxide particles was made based on the following idea.

Spherical silica particles: A large spacer effect can be imparted to the toner due to its large particle size, and the adhesive force and the contact area between the toner base particles can be reduced. Particularly, the degree of fluidization can be improved.
Titanium oxide particles: It is possible to increase the coverage of the toner base particles, increase the fluidity, and improve the avalanche energy change amount. Incidentally, the titanium oxide particles used in this example have a high average aspect ratio and a large contact area with the toner base particles, so that the titanium oxide particles are stably present on the toner surface, and the avalanche energy change amount even when used for a long period of time. Maintenance can be expected.

物 Physical properties of toner≪
[Measurement of fluidization degree]
Using a rotating drum / image analysis type powder fluidity measurement device (powder analyzer REVOLUTION, manufactured by Mercury Science Inc.), the measurement was performed according to the following procedure. Of the toners [1] to [22], 100 cm ³ of a sample to be measured was sealed in a rotating drum made of glass and attached to the powder fluidity measuring device. The rotating drum was rotated for 10 seconds at each rotating speed while gradually changing the rotating speed from 20 rpm to 80 rpm in steps of 5 rpm. The elevation of the powder surface was recorded by a CCD camera, and the height of the powder surface was quantified every 0.1 second at each rotation speed, and the average value was determined as the average height of the powder surface. The horizontal axis indicates the drum rotation speed (rpm), and the vertical axis indicates the average height of the powder surface (cm).

[Avalanche energy change]
Using a rotating drum / image analysis type powder fluidity measuring device (powder analyzer REVOLUTION, manufactured by Mercury Science Inc.) similar to the fluidization degree measurement, the measurement was performed in the following procedure.
Of the toners [1] to [22], a sample of 100 cm ³ to be measured was sealed in a rotating drum made of glass, and attached to the powder fluidity measuring device. The rotating drum was rotated at a low speed of 0.3 rpm, and an avalanche phenomenon was observed 200 times. The avalanche phenomenon was recorded by a CCD camera, subjected to numerical processing, and the difference between the potential energy decrease start point and the potential energy increase start point was calculated as the amount of change in the potential energy before and after the avalanche. This value was taken as the avalanche energy change.

≪Evaluation≫
[Preparation of Developers [1] to [22]]
To evaluate toners [1] to [22], developers [1] to [22] were prepared as described below.
Specifically, a ferrite carrier having a volume average particle diameter of 60 μm was added to the toners [1] to [22] so that the toner content (toner concentration) in the two-component developer was 7% by mass. Thereafter, the mixture was mixed by a V-type mixer for 30 minutes to obtain corresponding two-component developers [1] to [22].

[Evaluation 1: Toner supply property]
A copying machine “bizhub PRESS C1100” (manufactured by Konica Minolta) was subjected to the following actual test to evaluate toner replenishability.
A toner bottle is filled with 1200 g of toner, and 1000 sheets are printed at a printing rate of 100% using A4 size plain paper as an image support under conditions of normal temperature and normal humidity (temperature: 20 ° C., humidity: 55% RH). . If the toner supply to the machine is insufficient, the machine erroneously detects that the capacity of the toner bottle has run out, and turns on the "toner empty display". The toner replenishability was determined by the number of times the toner empty display was turned on when 1,000 sheets were printed. If the lighting was performed twice or less, there was no problem in practical use, and it was judged to be acceptable. The results are as shown in Table 3.

<Evaluation criteria>
○: The number of times of empty display is within 2 times ×: The number of times of empty display is 3 times or more

[Evaluation 2: Image quality (granularity)]
In a copying machine "bizhub PRESS C1100" (manufactured by Konica Minolta), the above developers 1 to 24 are loaded, and under the conditions of normal temperature and normal humidity (temperature 20 ° C., humidity 55% RH), A4 size high quality paper. (65 g / m ² ), a test image is printed as a test image to form a band-like solid image with a printing rate of 5% on 100 sheets, and a gradation pattern with a gradation ratio of 32 steps is outputted. The evaluation was performed according to evaluation criteria. The evaluation of graininess is performed by performing a Fourier transform process in consideration of MTF (Modulation Transfer Function) on the read value of the gradation pattern by the CCD, measuring the GI value (Graininess Index) in accordance with the relative luminosity factor of a human, and measuring the maximum value. The GI value was determined. The smaller the GI value, the better. If the value is less than 0.175, it is judged that there is no practical problem and the GI value is acceptable. The GI value is a value published in Journal of the Imaging Society of Japan 39 (2), 84.93 (2000). The results are as shown in Table 3.

<Evaluation criteria>
◎: GI is less than 0.165 ：: GI is 0.165 or more and less than 0.175 ×: GI is 0.175 or more

  From Table 3, it can be seen that, according to the present invention, even in the case of a toner for developing an electrostatic image into which a crystalline substance is introduced and which has a high adhesive force, an electrostatic image having good toner replenishability and image quality can be obtained in high-speed printing or high-coverage printing. It has been shown that toner for development can be provided

D Rotary drum T Toner T _s Powder surface R Rotary shaft

Claims (6)

A toner base particle containing a binder resin, a release agent, and a crystalline resin of a different type from the release agent, and an electrostatic charge image developing method including an external additive attached to the surface of the toner base particle Toner,
As the external additive, titanium oxide particles having an average aspect ratio (the number average major axis / the number average minor axis) derived from the ratio of the number average major axis to the number average minor axis are in the range of 2 to 15 A spherical silica particle having a number average particle diameter within a range of 60 to 100 nm, which is contained in the range of 0.10 to 0.80 parts by mass with respect to the toner base particle, Contained in the range of 0.05 to 0.80 parts by mass,
The titanium oxide particles have a rutile-type crystal structure,
The fluidization degree measured using a rotating drum / image analysis type powder fluidity measurement device is in the range of 0.50 to 0.90 cm / rpm, and
An avalanche energy change amount measured by using a rotating drum / image analysis type powder fluidity measuring device is in the range of 12.5 to 25.0 kJ / kg, the toner for developing an electrostatic image. .   2. The toner according to claim 1, wherein the fluidization degree is in a range of 0.65 to 0.90 cm / rpm.   The electrostatic image developing toner according to claim 1, wherein a volume-based median diameter (D50% diameter) of the toner base particles is in a range of 4.5 to 8.0 μm. 4.   4. The electrostatic image developing toner according to claim 1, wherein the crystalline resin contains a crystalline polyester resin.   The electrostatic crystalline image developing method according to claim 4, wherein the crystalline polyester resin is a hybrid crystalline polyester resin in which an amorphous resin segment and a crystalline polyester segment are chemically bonded. toner. A two-component developer for developing an electrostatic image, comprising the toner for developing an electrostatic image according to any one of claims 1 to 5 and carrier particles.