JP2000310876A - Developer for developing electrostatic images - Google Patents

Abstract

(57) [Problem] To provide a developer for developing an electrostatic image capable of maintaining good image quality even by high-speed, continuous printing. SOLUTION: (1) A developer for developing an electrostatic charge image having toner particles containing at least a binder resin and a colorant and an external additive is introduced into helium atmospheric pressure microwave induction plasma, and (2) silicon atom And excite and emit carbon atoms,
(3) Absolute error with respect to an approximate straight line indicating the state of attachment of silicon and carbon atoms, which is obtained based on the emission spectrum of silicon and carbon atoms in the developer obtained by measuring the intensity of the light emission over time. A developer for developing electrostatic images having a deviation of 0.3 or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a developer for developing an electrostatic image for visualizing an electrostatic latent image in an image forming method such as electrophotography.

[0002]

2. Description of the Related Art In general, in electrophotography, an electric latent image is formed on an electrostatic latent image carrier charged by an arbitrary means, and then the latent image is developed using a developer to form paper or paper. This is a method in which a developer image is transferred onto an OHP sheet or the like and then fixed by heating, pressurizing, or solvent vapor to obtain a printed matter. In an image forming apparatus for obtaining a printed matter by such an electrophotographic method, there are members which come into direct contact with a developer such as an electrostatic image carrier and a developing roll. The contact between the member and the developer may be repeated, and a part of the developer may adhere to the member. Such fixation to the member causes deterioration in image quality such as fogging. As a method of solving this, it has been proposed to externally add fine particles to toner particles, and various fine particles, mainly silica-containing compounds, such as silica particles and those obtained by treating them with silicone oil, have been studied as external additives. (Colloidal silica disclosed in JP-A-48-47346,
Japanese Patent Application Laid-Open No. Sho 50-120631, a hydrophobized colloidal silica treated with an organosilicon compound, a silica stone disclosed in Japanese Patent Application Laid-Open No. 52-63337, a fused alumina,
Silicon carbide, boron carbide, other carbides, nitrides, etc.).

However, even an external additive which is said to be excellent in preventing the developer from adhering to a member, it is possible to use one additive per minute.
20,000 using a device capable of high-speed printing of zero or more sheets
Under severe use conditions such as continuous printing of sheets, it was not possible to sufficiently prevent the developer from adhering to the members of the image forming apparatus.

[0004]

SUMMARY OF THE INVENTION The inventors of the present invention have made it possible to reduce adhesion of toner to an image forming apparatus member by attaching silicon-containing fine particles to toner particles in a specific state based on the prior art. As a result, the present invention has been completed.

[0005]

Thus, according to the present invention, there is provided (1) a developer for developing an electrostatic charge image having at least toner particles containing a binder resin and a colorant and an external additive; (2)
Excitation and emission of silicon and carbon atoms, and (3) silicon and carbon atoms determined based on the emission spectra of silicon and carbon atoms in the developer obtained by measuring the intensity of the emission with time And a developer for developing an electrostatic charge image having an absolute deviation of 0.3 or less with respect to an approximation straight line representing the state of adhesion.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. <Toner particles> In the invention, the toner particles contain at least a binder resin and a colorant. Examples of the type of the binder resin used in the present invention include polymers of styrene such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene and their substituted polymers; styrene-p-chlorostyrene copolymer, and styrene-vinyltoluene. Copolymer,
Styrene-vinylnaphthalene copolymer, styrene-acrylate copolymer, styrene-methacrylate copolymer, styrene-α-chloromethacrylate copolymer, styrene-acrylonitrile copolymer,
Styrene-vinyl methyl ether copolymer, styrene-
Aromatic vinyl copolymers such as vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, and cross-linking thereof Products: polyvinyl chloride, phenolic resin, natural modified phenolic resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy resin, xylene resin ,
Examples thereof include polyvinyl butyral, a terpene resin, a coumarone indene resin, and a petroleum resin. A crosslinked aromatic vinyl copolymer is also a preferred binder resin.

The aromatic vinyl copolymer styrene, α-
Specific examples of comonomers for aromatic vinyl monomers such as methylstyrene and 4-methylstyrene include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, and 2-ethylhexyl acrylate. Unsaturated monocarboxylic acids such as phenyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide and the like; maleic acid, butyl maleate , Unsaturated maleic dicarboxylic acids such as methyl maleate, dimethyl maleate and the like; vinyl esters such as vinyl chloride, vinyl acetate and vinyl benzoate; ethylene and propylene, butylene and the like Ethylenic olefins, vinyl methyl ketone, vinyl ketones such as vinyl hexyl ketone, vinyl methyl ether, vinyl ethyl ether, vinyl ethers such as vinyl isobutyl ether; and the like. These comonomers are used alone or as a mixture of two or more.

Further, as a comonomer, a crosslinkable monomer having two or more polymerizable double bonds can be used. Specific examples thereof include aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; and carboxylic acids having two double bonds such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, and 1,3-butanediol dimethacrylate. Acid esters; divinyl compounds such as divinylaniline, divinyl ether, divinyl sulfide and divinyl sulfone; and compounds having three or more vinyl groups. These are also used alone or as a mixture.

In the present invention, a colorant for black or color toner is used as the colorant. Examples of the black colorant include carbon black, nigrosine-based dyes and pigments; magnetic particles such as cobalt, nickel, iron tetroxide, iron manganese oxide, iron zinc oxide, and nickel iron oxide; When carbon black is used, the primary particle size is 2
It is preferable to use a layer having a thickness of from 0 to 40 nm because good image quality can be obtained and the safety of the toner to the environment is enhanced. Examples of the colorant for a color toner include Neftor Yellow S, Hansa Yellow G, C.I. I. Pigment Yellow, C.I.
I. Bat Yello, Eosin Lake, C.I. I. Pigment red, C.I. I. Pigment violet, C.I. I.
Bat red, phthalocyanine blue, C.I. I. Pigment blue, C.I. I. Bat blue, C.I. I. Acid blue and the like. These coloring agents are used in a proportion of usually 0.1 to 50 parts by weight, preferably 1 to 20 parts by weight, based on 100 parts by weight of the binder resin component.

An additive may be added to the toner particles of the present invention, if necessary. Additives include release agents, charge control agents, macromonomers, lubricants such as zinc stearate, or cerium oxide, abrasives such as silicon carbide, or anti-caking agents, or, for example,
Examples include conductivity imparting agents such as carbon black and tin oxide.

The release agent is used for the purpose of improving the releasability at the time of fixing with a hot roll, and specific examples thereof include polyfunctional ester compounds such as pentaerythritol tetrastearate, pentaerythritol tetramyristate and pentaerythritol tetrapalmitate. , Low molecular weight polyethylene, low molecular weight polypropylene, microcrystalline wax, carnauba wax, sasol wax, paraffin wax and the like. The release agent can be added at a ratio of about 0.5 to 5% by weight based on the toner particles.

As the charge control agent, various positively or negatively chargeable charge control agents can be used. Specific examples of the charge control agent include a metal complex of an organic compound having a carboxyl group or a nitrogen-containing group, a metal-containing dye, and nigrosine. More specifically, Spiron Black TRH (Hodogaya Chemical Co., Ltd.), T-77 (Hodogaya Chemical Co., Ltd.), Bontron S-34 (Orient Chemical Co., Ltd.),
Bontron E-84 (manufactured by Orient Chemical), Bontron N-01 (manufactured by Orient Chemical), copy blue-
PR (manufactured by Hoechst), a quaternary ammonium (salt) group-containing copolymer, and a sulfonic acid (salt) group-containing copolymer. The charge control agent is used in an amount of 0.01 to 10 parts by weight, preferably 0.03 to 8 parts by weight, based on 100 parts by weight of the binder resin component.

In the production of the polymerization toner, the use of a macromonomer as the polymerizable monomer can improve the balance between the storability and the fixability. The macromonomer has a vinyl polymerizable functional group such as an acryloyl group or a methacryloyl group at a terminal of a molecular chain, and is an oligomer or a polymer having a number average molecular weight of about 1,000 to 30,000. The amount of the macromonomer is usually 0.01 to 10 parts by weight, preferably 0.03 to 5 parts by weight, more preferably 0.1 to 100 parts by weight based on 100 parts by weight of the binder resin component.
It is 0.5 to 1 part by weight.

In producing the toner particles according to the present invention, after the toner constituent materials are sufficiently mixed by a ball mill or other mixer, they are kneaded well using a hot kneader such as a hot roll kneader or an extruder, and then cooled and solidified. A method of obtaining a toner by mechanical pulverization and classification; a method of dispersing a constituent material in a binder resin solution and then spray-drying to obtain the toner; After mixing the materials to form a suspension, the mixture is polymerized to obtain a toner. In particular, from the viewpoints of image quality and durability in continuous printing, it is preferable to employ a method for producing a toner by a polymerization method. The toner obtained by the polymerization method may be a polymerization toner having no layer structure or a so-called core-shell toner (capsule toner) having a layer structure. Further, such toner particles may include silicon atoms derived from the production process, such as a polymerization initiator and a dispersion stabilizer used for producing the binder resin.

It is preferable that the toner particles used in the present invention have a substantially spherical shape in order to obtain good image quality. Such substantially spherical toner particles have a volume average particle size (d
v) is 3 to 15 μm, preferably 5 to 10 μm, and the ratio (dv / dn) of the volume average particle diameter to the number average particle diameter (dn) is 1
~ 1.4, the area of a circle whose diameter is the absolute maximum length of the particle (S
c) divided by the actual projected area (Sr) of the particle (Sc /
Sr) is in the range of 1 to 1.3, and the BET specific surface area (A)
(M ² / g), the product (A × dn × D) of the number average particle size (μm) and the true specific gravity (D) are preferably in the range of 5 to 10.

<External Additives> In the present invention, fine particles containing silicon atoms (hereinafter sometimes referred to as silicon-containing fine particles) are used as the external additives. The average particle diameter of the silicon-containing fine particles,
From the viewpoint of imparting the fluidity of the toner, the thickness is preferably 5 nm to 100 nm. If the average particle size is too small, the toner tends to be embedded in the surface of the toner, and the deterioration of the toner occurs quickly, and the durability tends to decrease. Conversely, if the particle size is too large, the fluidity of the toner will be significantly reduced, resulting in non-uniform charging. As a result, deterioration of image quality, toner scattering and fogging are likely to occur. The average particle size of the fine particles of the present invention is a value measured for 50 particles by a transmission electron microscope.

In the present invention, the silicon-containing fine particles serving as the external additive include silicates such as silica, aluminum silicate, sodium silicate, potassium silicate, magnesium silicate, and zinc silicate; [M] a [Si] bOc (M is Sr,
Mg, Zn, Co, Mn, Ce, etc., and a and b
Are each independently an integer of 1 to 9, and c is an integer of 3 to 9). Silicon-containing composite metal oxides; silicon-containing polymers such as polysiloxane; Fine particles of alumina oxide, alumina calcium carbonate, barium titanate, zinc oxide, composite metal oxide, etc.
Surface treatment with a silicon-containing compound such as a silane coupling agent, polysiloxane, or hydrogen polysiloxane may be used.

More specifically, silicic acid (JP-A-62-2
No. 91666), silica fine powder treated with silicon oil (Japanese Patent Application Laid-Open No. 61-277964), titanium oxide fine particles whose surface is treated with silica and a silane compound or a silicone compound (Japanese Patent Application Laid-Open No.
No. 56380), and inorganic fine particles such as aluminum oxide, silicon oxide and titanium oxide surface-treated with a silicone polymer or oligomer such as silicone oil or silicone varnish having a nitrogen atom in the side chain (JP-A-7-2952).
No. 84), RmSiYn (R is an alkoxy group, Y is an alkyl group, a vinyl group, a phenyl group, a methacryl group,
Inorganic fine powder treated with a silane coupling agent represented by an amino group, an epoxy group, a mercapto group, and m and n are each independently an integer of 1 to 3 (JP-A-8-137126).
JP-A-8-2020), inorganic fine powder surface-treated with polysiloxane and hydrogen polysiloxane.
No. 79), resin fine particles surface-treated with silicone oil (Japanese Patent Application Laid-Open No. 62-237462,
68822), inorganic fine particles obtained by treating a silicon-containing composite oxide with a silicone oil or a silane coupling agent (JP-A-10-142831, JP-A-10-19).
No. 8062) and titanium oxide fine powder treated with a silane coupling agent (JP-A-5-188633). These silicon-containing fine particles can be used alone or in combination.

These silicon-containing fine particles are attached to toner particles as an external additive. As a method of attaching the external additive,
Henschel mixer with toner particles and silicon-containing fine particles,
A method in which the mixture is charged into a mixer such as a super mixer or a surface reformer such as a hybridizer or an ang mill and stirred. By controlling the rotation speed (peripheral speed) and rotation time of a device such as a mixing blade for mixing the contents, it is possible to adjust a standard deviation of an error with respect to an approximate straight line described later. In the present invention, fine particles other than the silicon-containing fine particles can be used in combination as an external additive.

The amount of the external additive is 0.1% with respect to the toner particles.
~ 5% by weight is suitable. If this amount is small, it is difficult to obtain high fluidity of the toner, and if it is large, on the contrary, uniform charging is hindered because the fluidity of the toner is too high,
Fog becomes easy.

The developer of the present invention can be mixed with a carrier and used as a two-component developer. As the carrier that can be used in the present invention, known carriers can be used,
For example, powders having magnetism such as iron powder, ferrite powder, and nickel powder, glass beads, and the like, and those obtained by treating the surfaces thereof with a resin or the like are listed. Further, as the resin for coating the carrier surface, styrene-acrylate copolymer, styrene-methacrylate copolymer, acrylate copolymer, methacrylate copolymer, silicone resin, fluorine-containing resin, A polyamide resin, an ionomer resin, a polyphenylene sulfide resin, or the like, or a mixture thereof can be used.

<Adhesion state of silicon atom and carbon atom and approximate straight line> The toner particles according to the present invention contain many carbon atoms, and the external additive containing silicon-containing fine particles contains many silicon atoms. Even if the external additive may contain carbon atoms, the amount is small relative to the amount of carbon atoms in the toner particles. Similarly, if silicon atoms are included in the toner particles, the amount is still small relative to the silicon atoms in the external additive. Therefore, if a substance containing a silicon atom is used as the external additive, the state of adhesion of the silicon-containing fine particles to the toner particles in the developer can be grasped by analyzing the silicon atom and the carbon atom. The analysis of silicon atoms and carbon atoms consists of (1) introducing a large number of fine particles into helium atmospheric pressure microwave induced plasma, (2) exciting and emitting a specific element in the particles, and (3) intensity of the emission. Is performed based on the emission spectra of silicon atoms and carbon atoms obtained by using a fine particle measuring apparatus employing a method of continuously measuring the emission of carbon atoms.

Specifically, such a device includes a microwave source described in Japanese Patent Publication No. 7-54294, a cavity for introducing a microwave generated by the microwave source, and a vicinity of the center of the cavity. A reaction tube having a detection window at one end provided therethrough, a capillary tube having one end connected to the other end of the reaction tube at the other end under normal pressure, and arranged in a space containing fine particles; An evacuation means for reducing the pressure; and an analysis means provided adjacent to the detection window of the reaction tube, wherein the evacuation means reduces the pressure in the reaction tube to an extent capable of atomization / ionization. A gas is introduced to generate plasma by the microwave, and a sample gas under normal pressure is introduced by the capillary tube to contain the sample gas. Particle monitor can be cited and performs qualitative and quantitative analysis of the particles by analyzing by the analyzer emission spectrum of ions generated in the reaction tube in-line by the fine particles.

According to such a fine particle measuring apparatus, the element A
And particles containing element B are mixed,
By obtaining the emission spectrum of each element using the element A and the element B as the measurement target elements, it is possible to quantitatively evaluate the attached (including) state, the dispersed state, and the free state of the particles. When the two particles are separated, the element A and the element B emit light separately, so that an asynchronous emission spectrum having a shift with respect to the time axis is obtained (see FIG. 1). Also, if two particles are attached (including the case where one contains one),
Since the elements A and B emit light at the same time, a synchronous emission spectrum having no shift with respect to the time axis is obtained (see FIG. 2). From the intensity of the synchronous emission spectrum, particles containing element A and element B
The number of the atoms of the element A and the element B per one adhered particle to which the particles containing the particles are adhered can be obtained as a (cubic root) voltage. Therefore, a large number of samples are analyzed at once, and the x-axis is
In the distribution chart in which the voltage of the synchronous emission spectrum of (1) and the y-axis are the voltage of the synchronous emission spectrum of element B, a straight line passing through the origin calculated by the least squares method can be drawn (see FIG. 3). This straight line is an approximate straight line representing the state of adhesion between the particles containing element A and the particles containing element B.

The approximate straight line obtained by taking the voltage from the silicon atom and the carbon atom on the x-axis and the voltage from the silicon atom on the y-axis for the developer using the above-described device is the adhesion state between the silicon atom and the carbon atom. That is, it indicates the state of adhesion of the silicon-containing fine particles to the toner particles. The error with respect to the approximate straight line is an error value x = d / H (d is the length of a perpendicular from the data point to the approximate straight line, and H is the length of the perpendicular from the intersection of the approximate straight line and the perpendicular to the X axis). The value of the absolute deviation of this error is
1 / n (Σ | xx ′ |) (n is the number of error data,
x ′ is obtained by the average value of the error data). In the present invention, when the absolute deviation calculated in this way is 0.3 or less, preferably 0.25 or less, and more preferably 0.2 or less, two or more high-speed printing machines with 10 or more sheets per minute are required.
Even when 000 sheets are continuously printed, the developer does not cause filming on the members of the image forming apparatus, and good image quality without fogging or blurring can be maintained.

The inclination of the approximate straight line is preferably 0.5 or less, more preferably 0.1 to 0.45, particularly preferably 0.2 to 0.45, from the viewpoint of image quality during continuous printing.
It is. The ratio of free silicon to total silicon determined from the asynchronous emission spectrum can be regarded as the ratio of free silicon-containing fine particles released from toner particles. The free silicon ratio is 20% by number or less, more preferably 15% by number or less, further preferably 10% by number or less. If the amount of the free silicon-containing fine particles is too large, the free silicon-containing fine particles tend to adhere to an image forming apparatus member such as a photoreceptor, and the portion becomes a nucleus to fix the toner.

In the present invention, the absolute deviation, the slope, and the free silicon ratio are obtained as an average of three data obtained by repeating the operation of obtaining each value five times and excluding the maximum value and the minimum value of each of the five data. It is a thing.

[0028]

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples. Parts and percentages are by weight unless otherwise specified.

(Approximate straight line) Using a particle analyzer (trade name “Particle Analyzer PT1000”, manufactured by Yokogawa Electric Corporation) with carbon atoms and silicon atoms as atoms to be analyzed, the following conditions were repeated as one cycle for 5 cycles. The emission spectra of carbon and silicon atoms of the developer were measured. In addition, using the "toner analysis software version 2.00" manufactured by Yokogawa Electric Corporation as the analysis software for the spectrum data,
A distribution diagram of the voltage of carbon atoms and the voltage of silicon atoms (x-axis voltage of carbon atoms, y-axis voltage of silicon atoms) was obtained, and an approximate straight line was obtained. The slope of the approximate straight line and the absolute deviation from the approximate straight line were calculated by the same software. The external additive release rate (the unit in the table is “number%”) is calculated by the software based on the voltage obtained from the asynchronous emission spectrum data of silicon atoms and the voltage obtained from the emission spectrum data of total silicon atoms. Calculated.

The conditions for measuring the fine particles are as follows. Number of carbon atoms counted in one scan: 500 to 1500 Number of scans: 8 Toner suction device: Low volume sampler manufactured by Yokogawa Electric Corporation (product name "LV1000") Toner suction chip: Chip manufactured by Eppendorf (grade "100 .mu.l") Toner Suction tube: Norton Tygon tube (trade name “R-3603” (tube inner diameter φ6.35 m)
m × length 50mm) Filter: Corning filter (trade name “New lipore membrane filter” 0.4μm)

(Evaluation of Toner Performance) In this example, image quality was evaluated as follows using a commercially available non-magnetic one-component developing system printer (12-sheet machine). (Image quality) Continuous printing was performed in the above-mentioned printer at 23 ° C. × 50 RH% room temperature environment, and the number of continuous prints until a printing defect such as blurring (white stripes or white spots) on the paper surface was examined. The larger the number of printed sheets, the more difficult it is for the developer to adhere to the image forming apparatus member (filming).

(Fog) Environmental dependence (H / H, L / L) Using the printer described above, 35 ° C. × 80 RH% (H / H
H) Continuous printing was performed from the beginning in each environment of 10 ° C. × 20 RH% (L / L) environment. Under these conditions, a continuous image quality can be maintained in which the print density is 1.3 or more with a reflection densitometer (manufactured by Macbeth) and the fog of the non-image area measured by a whiteness meter (manufactured by Nippon Denshoku) is 15% or less. The number of printed sheets was checked. When the whiteness B after printing and the whiteness before printing are A,
Fog value calculated by the following formula: fog = ((B−A) / A) × 100 was used. -Durability Continuous printing was performed from the beginning with the above-mentioned printer in a 23 ° C. × 50 RH% room temperature environment. Under these conditions, when the print density measured by a reflection densitometer (manufactured by Macbeth) is 1.3 or more,
In addition, the number of continuous printed sheets capable of maintaining an image quality of 15% or less of fog in the non-image area measured by a whiteness meter (manufactured by Nippon Denshoku) was examined, and the durability of the image quality by the developer was evaluated.

Reference Example 1 80.5 parts of styrene and n
-Core polymerizable monomer composed of 19.5 parts of butyl acrylate, 0.3 part of polymethacrylic acid ester macromonomer (trade name "AA6", manufactured by Toa Gosei Chemical Industry Co., Ltd.), 0.5 part of divinylbenzene, t- Dodecyl mercaptan
2 parts, carbon black (Mitsubishi Chemical Corporation, trade name "# 2
5B "), 1 part of a charge controlling agent (trade name" Spiron Black TRH "manufactured by Hodogaya Chemical Co., Ltd.), and 2 parts of a release agent (trade name" Paraflint H1 "manufactured by Sasol Co., Ltd .: Fischer-Tropsch wax) Then, wet pulverization was performed using a media type wet pulverizer to obtain a polymerizable monomer composition A for a core.

On the other hand, in an aqueous solution obtained by dissolving 10.2 parts of magnesium chloride (water-soluble polyvalent metal salt) in 250 parts of ion-exchanged water, 6.2 parts of sodium hydroxide (alkali metal hydroxide) in 50 parts of ion-exchanged water. An aqueous solution in which was dissolved was gradually added under stirring to prepare a magnesium hydroxide colloid (poorly water-soluble metal hydroxide colloid) dispersion liquid A. The particle size distribution of the produced colloid was measured with a Microtrac particle size distribution analyzer (manufactured by Nikkiso Co., Ltd.).
0 (50% cumulative value of the number particle size distribution) is 0.35 μm,
D90 (90% cumulative value of number particle size distribution) is 0.84 μm
Met. In the measurement by this Microtrac particle size distribution measuring instrument, the measurement range = 0.12 to 704 μm,
The measurement was performed under the conditions of measurement time = 30 seconds and medium = ion-exchanged water.

On the other hand, 3 parts of methyl methacrylate and 10 parts of water
0 parts was finely dispersed by an ultrasonic emulsifier to obtain an aqueous dispersion A of a polymerizable monomer for shell. The particle size of the droplets of the polymerizable monomer for shell was determined by adding the obtained droplets to a 1% aqueous sodium hexametaphosphate solution at a concentration of 3% and measuring with a Microtrac particle size distribution analyzer. 0.6μ
m.

The polymerizable monomer composition A for a core is added to the magnesium hydroxide colloidal dispersion A obtained as described above, and the mixture is stirred until the droplets are stabilized. After adding 6 parts of oxy-2-ethylhexanoate (trade name "Perbutyl O", manufactured by NOF CORPORATION), it is rotated at 15,000 rpm with an Ebara Milder (trade name, manufactured by Ebara Corporation) at 30 rpm. After high shear stirring for minutes, the droplets of the monomer mixture were granulated. The aqueous dispersion of the granulated monomer mixture was put into a reactor equipped with a stirring blade, and a polymerization reaction was started at 85 ° C., and the polymerization conversion was almost 1%.
After reaching 00%, a water-soluble initiator (trade name "VA-0" manufactured by Wako Pure Chemical Industries, Ltd.) was added to the aqueous dispersion A of the polymerizable monomer for shell.
86 ": 2,2'-azobis (2-methyl-N- (2-
Hydroxyethyl) -propionamide))) 0.3
The portion was dissolved and placed in the reactor. After the polymerization was continued for 4 hours, the reaction was stopped, and the polymer particles were dehydrated and dried to obtain toner particles.

The volume average particle diameter (d) of the obtained toner particles
v) is 7.1 μm, the volume average particle size and the number average particle size (d
n) is a ratio (dv / dn) of 1.2, and the area (Sc) of the circle whose diameter is the absolute maximum length of the particle is the actual projected area (S
r) is 1.2, the product of the BET specific surface area (A), the number average particle diameter and the true specific gravity (D) (A ×
dn × D) was 7.3. The volume average particle diameter (dv) and the number average particle diameter (dp) are as follows:
m, medium: Isoton II, concentration 10%, number of measured particles:
It is a value (μm) measured with a Multisizer (manufactured by Coulter) under the condition of 50,000 pieces. (Sc / S
In r), an electron micrograph of the toner particles is taken, and the photograph is taken by an image processing / analysis apparatus Luzex IID (manufactured by Nicole Co., Ltd.) to have an area ratio of the particles to the frame area of 2% at the maximum and the total number of the processed particles: 1000. It is the number average value of the values of 1000 pieces measured and analyzed under the same conditions. The specific surface area (A) is a value (m ² / g) measured by a BET method using an automatic specific surface area measuring device Model 2200 manufactured by Shimadzu Corporation. The true specific gravity (D) is a value measured by a Beckman hydrometer.

Examples 1 to 3 and Comparative Examples 1 and 2 Hydrophobized silica having an average particle diameter of 12 nm (trade name "RX2" manufactured by Degussa Co., Ltd.) was added to 100 parts of the toner particles obtained above.
00 ") and mixed to obtain Developers A to E. The mixing conditions are as follows. The image quality of the obtained developer was evaluated.

The mixer used was a Henschel mixer (model "FM10B", manufactured by Mitsui Miike Kakoki Co., Ltd.). The temperature at the time of mixing was 25 ° C., and the humidity was 50 RH%. After charging the toner particles and the silica into the mixing tank of the mixer, the peripheral speed of the developer A is increased from zero to 40 m / sec in 5 seconds. The state is maintained for 30 seconds after the peripheral speed reaches 40 m / sec. Thereafter, the peripheral speed is reduced to 0 in 5 seconds. Next, the state is maintained for 30 seconds after the peripheral speed reaches zero. This cycle was repeated one cycle for five cycles (the total time when the peripheral speed was 40 m / sec was 1
50 seconds).

The developer B was externally added in the same manner as the developer A, except that the peripheral speed maintained after the acceleration was 30 m / sec and the number of cycles was changed to six. The developer C was externally added in the same manner as the developer A, except that the maintenance time at a peripheral speed of 40 m / sec in one cycle was 40 seconds and the number of cycles was changed to 4 cycles. The developer D was externally added in the same manner as the developer A except that the maintenance time at a peripheral speed of 40 m / sec in one cycle was set to 75 seconds and the number of cycles was changed to two. For the developer E, the peripheral speed in one cycle was 40
Assuming that the maintenance time at m / sec is 150 seconds, the number of cycles is 1
External addition was carried out in the same manner as in developer A except that the cycle was changed.

With respect to the obtained developer, the external addition state was measured and the toner performance was evaluated. Table 1 shows the results. still,
The units of the values in the table are all “sheets”, and are values obtained by cutting off less than 1000 sheets.

[0042]

[Table 1]

From the above results, the developer for developing an electrostatic image having an absolute deviation of 0.3 or less with respect to an approximate straight line representing the state of attachment of the silicon-containing fine particles to the toner particles is 1 minute per minute.
It was found that an image forming apparatus that prints 20,000 sheets (durable printing) gave an image quality free from filming, fogging, and blurring even when printing 20,000 sheets (durable printing).

[0044]

According to the developer for developing an electrostatic image of the present invention, good image quality can be maintained even at high speed and continuous printing.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an asynchronous emission spectrum.

FIG. 2 is a diagram illustrating an asynchronous emission spectrum.

FIG. 3 is a diagram illustrating an approximate straight line obtained from a synchronous emission spectrum.

[Explanation of symbols]

 1 Particle containing element A 2 Particle containing element B 3 Emission spectrum of element A 4 Emission spectrum of element B 5 Approximate straight line 6 Data plot

Claims (2)

[Claims] 1. A developer for developing an electrostatic image having toner particles containing at least a binder resin and a colorant and an external additive is introduced into helium atmospheric pressure microwave induction plasma, and (2) silicon Excitation and emission of atoms and carbon atoms,
(3) Absolute error with respect to an approximate straight line indicating the state of attachment of silicon and carbon atoms, which is obtained based on the emission spectrum of silicon and carbon atoms in the developer obtained by measuring the intensity of the light emission over time. A developer for developing electrostatic images having a deviation of 0.3 or less. 2. The developer according to claim 1, wherein the slope of the approximate straight line is 0.5 or less.