JP3535082B2 - Electrostatic image developing toner and image forming method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner for developing an electrostatic charge image in an image forming method such as electrophotography to form a toner image.

[0002]

2. Description of the Related Art The functions of image forming apparatuses using electrophotography, such as copying machines and laser beam printers, have been diversified, and further higher definition and higher image quality have been demanded. Along with this, the toner particles tend to have finer particle diameters than ever before. However, when the particle size of the toner particles is reduced, the material dispersibility of each toner is further required. When the toner diameter is reduced to small particles with the conventional dispersibility, high definition of the image is achieved,
Image density lowering and fog phenomenon are likely to occur due to poor charging, and the scattering of toner inside the machine often causes a problem.

As a means for solving the above-mentioned problems, Japanese Patent Laid-Open No. Hei 1
No. 1-344829, in a toner containing a binder resin, a colorant and a wax component, by improving the dispersibility between the raw materials in the toner by reducing the residual monomer amount in the toner as much as possible, A new toner and an image forming method in which the charging property and blocking resistance of the toner are improved have been proposed. However, the binder resin in which only the amount of residual monomer is reduced requires a strict demonomer treatment, which not only is disadvantageous in terms of cost, but when this is used, the effect of residual monomer in the toner is reduced. However, on the contrary, it is greatly affected by organic volatile components contained in other materials such as carbon black, and often causes a decrease in offset resistance during heat fixing and a decrease in blocking resistance due to toner aggregation. It was.

Many of the organic volatile components contained in carbon black have compounds having a vinyl group in the benzene skeleton, and these compounds have the property of undergoing a thermal polymerization reaction with the residual vinyl monomer in the binder resin during toner production. ing. However, if the amount of residual monomers in the binder resin is small during melt-kneading, these residual monomers will volatilize and a sufficient thermal polymerization reaction will not occur, so that only organic volatile components remain as monomers even after toner generation. However, it is considered that such a problem was caused by the presence of a low molecular weight polymer (oligomer) having a very low softening point.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrostatic charge developing toner capable of solving the above-mentioned problems, and more particularly, an electrostatic charge developing toner excellent in blocking resistance and offset resistance. An object of the present invention is to provide an image forming method using.

[0006]

Means for Solving the Problems As a result of various studies for solving the above-mentioned problems, the present inventors have found that the binder resin remains in the binder resin at the time of melt-kneading the toner containing the binder resin and carbon black. By optimizing the monomer and reducing the amount of organic volatile components in the entire toner as much as possible, it is possible to improve the dispersibility between the raw materials in the toner and to obtain a toner with excellent blocking resistance and offset resistance. Heading The present invention has been completed.

That is, the present invention relates to an electrostatic image developing toner obtained by melt-kneading at least a binder resin, a colorant, an antistatic agent and magnetic fine powder, cooling and finely pulverizing the toner,
The binder resin at the time of melt-kneading has a residual monomer content of 200 to 10
00ppm softening point of the content is styrene-based resin one hundred forty-five to one hundred and sixty-five ° C., the colorant is a carbon black containing at least organic volatile components, steel during melt kneading
Melt kneading 15 ° C to 30 ° C higher than the softening point of ren resin
By heating to the temperature, the organic volatile components in the carbon black are reduced by the thermal polymerization reaction with the residual monomer in the binder resin, and the weight average particle size thereof is 7.5 to 1
0.5 μm and true specific gravity (g / cc) of 1.1 to
The present invention relates to a toner for developing an electrostatic charge image characterized by having a ratio of 1.3.

The binder resin used in the present invention has a softening point of 145 ° C. to 165 ° C. and a residual monomer amount of 200 p.
It is a resin selected from the group consisting of a styrene-based polymer, a styrene-based copolymer, a styrene-acrylic acid ester-based copolymer, a styrene-methacrylic acid ester-based copolymer, and a mixture thereof of pm to 1000 ppm. preferable.

When the content of the magnetic fine powder in the toner of the present invention is 1 to 10% by weight, 79.58 kA / m (1
A toner for developing an electrostatic charge image in which the saturation magnetization [σs (Am2 / kg)] of the toner under a magnetic field of (K Oersted) satisfies the following conditions is preferable. 0.1 <σs <3.0 Furthermore, the toner of the present invention has a dielectric loss (ta
nδ (× 10 ^-3 )) and electric resistance (R (× 10 ⁺⁹ ))
It is preferable that the following conditions are satisfied. 1.5 <tan δ <4.0, 200 <R <350

Furthermore, according to the present invention, a magnet is installed as a two-component developer in which at least the toner developer is mixed with a magnetic carrier as an independent developing cartridge that is detachable from the main body of the image forming apparatus (magnetic sleeve). The present invention relates to an image forming method, which comprises electrostatically adhering to a surface of a developer carrier, and adhering toner to an electrostatic charge image on an electrostatic charge image carrier to develop the image. Further, according to the present invention, the clearance between the electrostatic image holding member and the developer carrying member holding the toner is 1 mm or more, and an image used in an image forming apparatus incorporated as a detachable process cartridge in the main body of the image forming apparatus. It relates to a forming method.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below. First, the toner for developing an electrostatic image of the present invention has a weight average particle diameter of 7.5 to 10.5 μm,
The true specific gravity (g / cc) is 1.1 to 1.3, and the organic volatile components in the carbon black are reduced by the thermal polymerization reaction with the residual monomer in the binder resin during melt-kneading. There is. Here, the true specific gravity of the toner particles or the toner is measured using a pycnometer cell, which is a pycnometer. The weight average particle diameter is measured by the Coulter counter method. As a measuring device for the toner particles and the average particle diameter of the toner by the Coulter counter method, for example, Coulter Counter TA-II or Coulter Multisizer (manufactured by Coulter Co.) is used. As the electrolytic solution, about 1% NaCl aqueous solution is prepared using first-grade sodium chloride. For example, ISOTON-II (manufactured by Coulter, Inc.) can be used. As the measuring method, the electrolytic aqueous solution 1
A surfactant (preferably an alkylbenzene sulfonate) as a dispersant is added in an amount of 0.1-5 in 0-150 ml.
ml, and 2 to 20 mg of the measurement sample is further added.

The electrolytic solution in which the sample is suspended is dispersed by an ultrasonic disperser for about 1 to 3 minutes.
Using a 1300 μm aperture as the aperture, the volume and number of toner particles or toner are measured to calculate the volume distribution and number distribution. Then, the weight average particle diameter (D4) of the toner particles or the toner weight basis is determined.
In the above measuring method, even if an external additive is externally added to the toner particles, the weight average particle diameter of the toner usually shows substantially the same value as the weight average particle diameter of the toner particles. As the channel, 2.00 to less than 2.52 μm; 2.52 to 3.
Less than 17 μm; 3.17 to less than 4.00 μm; 4.00
˜5.04 μm; 5.04˜6.35 μm;
6.35 to less than 8.00 μm; 8.00 to 10.08 μ
less than m; 10.08 to less than 12.70 μm; 12.70
˜16.00 μm; 16.00-20.20 μm; 20.20-25.40 μm; 25.40-3
Less than 2.00 μm; using 13 channels of 32.00 to less than 40.30 μm, and having a particle size of 2.00 μm or more to 4
Target particles are less than 0.30 μm.

Here, in order to faithfully reproduce the electrostatic latent image in 1-dot units on the photosensitive drum, the weight average particle diameter of the toner is preferably 10.5 μm or less. However, when the average particle size is 7.5 μm or less, the toner scattering increases in the developing system of the present invention. This is because as the particle size of the toner decreases, the number of particles not controlled by the electrostatic force increases. Usually, when the clearance between the sleeve of the developer carrying member and the photosensitive drum is as narrow as 1 mm or less, the above-mentioned toner scattering is small, but in the process cartridge detachable from the main body of the image forming apparatus of the present invention, the above-mentioned clearance is small. This is because the effect becomes more remarkable because the thickness is 1 mm or more.

The true specific gravity of the toner of the present invention (g / c)
c) is preferably 1.1 to 1.3. However, true specific gravity is 1.1
In the following, the difference in specific gravity from the magnetic carrier becomes too large, resulting in a decrease in mixing efficiency, which is one of the causes of toner scattering and fogging due to poor charging of the replenishment toner, which is not preferable. When the true specific gravity is 1.3 or more, a strong centrifugal force is applied as the developing sleeve rotates. If the centrifugal force is larger than the combined force of the magnetic force and the electrostatic force, the toner will be scattered, which is not preferable. The true specific gravity can be adjusted by adjusting the blending amount of the magnetic fine powder, the pigment, and the like contained in the toner particles.

As an image developing method in which the toner of the present invention is preferably used, a two-component developer in which toner and a magnetic carrier are mixed is used, and a magnet is installed in a developer carrying body. With this magnet, two components of the toner and the magnetic carrier are provided. Examples include a method of holding a developer, performing triboelectric charging on a developer carrier (carrier), and adhering the charged toner to the electrostatic charge image of the electrostatic charge image carrier to develop. In the toner of the present invention, 79.58 kA / m (1 k
Saturation magnetization [σ of toner under magnetic field of Oersted]
s (Am ² / kg)] preferably satisfies the condition of 0.1 <σs <3.0. Saturation magnetization s is 0.1
When it is less than Am ² / kg, the magnetic binding force is weak and the fog phenomenon cannot be suppressed, which is not preferable. Saturation magnetization s is 3.0A
When it is m ² / kg or more, the magnetic binding force becomes dominant and the image density becomes low, which is not preferable. In this case, the relationship between the residual magnetization [σr (Am ² / kg)] and the saturation magnetization [σs (Am ² / kg)] of the magnetic fine powder is σr / σs <0.2.
It is preferably 5.

In such a developing method, the weight average particle diameter of the toner of the present invention is 7.5 to 10.5 μm.
When the above toner particles are used, the phenomenon of fogging in a high temperature and high humidity environment, the phenomenon of a solid black density at the time of durability, and the phenomenon of magnetic fine powder drum fusion in a low temperature and low humidity environment tend to occur. These problems can be effectively solved by controlling the magnetic force (σr / σs) of the magnetic fine powder in the toner. In a high temperature and high humidity environment, magnetic force is applied to the toner so as to suppress fog development of toner with a low triboelectric charge amount, so that image density is maintained and fog is better prevented. can do.

Further, by controlling the amount of the magnetic fine powder on the surface of the toner carrier by optimizing the melt-kneading condition and the amount of the magnetic fine powder, it is possible to prevent the magnetic powder from being fused to the photosensitive drum at the time of endurance in a low temperature and low humidity environment. Is possible. Further, even in a high temperature and high humidity environment, toner particles having a high triboelectric charge amount are easily developed selectively and fogging and scattering can be suppressed. Magnetic force of magnetic fine powder in toner σr / σs
When a magnetic fine powder having a particle size of 0.25 or more is used, the magnetic binding force does not work effectively, so fogging is likely to occur in a high temperature and high humidity environment, and a solid black density thinning phenomenon during durability tends to occur, resulting in a low temperature.・ Drum fusion tends to occur in low humidity environment. When σr / σs is less than 0.05,
On the contrary, the magnetic restraint force becomes dominant and the image density tends to be lowered in all environments, which is not preferable. A more preferable range is 0.1 <σr / σs <0.2. Here, the magnetic characteristics are measured by using VSMP-1-10 (manufactured by Toei Industry Co., Ltd.) in an external magnetic field of 79.58 kA / m.

The toner of the present invention contains magnetic fine powder. Examples of the magnetic fine powder used here include magnetic metal oxides containing elements such as iron, cobalt, nickel, copper, magnesium, manganese, aluminum, and silicon. The weight average particle diameter of these magnetic fine powders is preferably 0.05 to 0.30 μm. When the weight average particle diameter is smaller than 0.05 μm, the dispersion tends to be poor due to the physical shearing force, and in the case of the toner, the magnetic force is not uniform and the magnetic binding force may differ depending on the magnetic field direction, which is not preferable. When the weight average particle diameter is larger than 0.30 μm, the number required for uniformly dispersing a small amount of magnetic fine powder as in the present invention is small, which is also not preferable because the magnetic binding force varies greatly. Further, the shape of the magnetic fine particles constituting the magnetic fine powder used in the present invention includes octahedron, hexahedron and sphere. In order to prevent rotation in the dispersion process and to achieve high dispersion, an octahedral shape that is more susceptible to shearing force is preferable because the image density and the latitude of fog can be wide.

Further, in order to satisfy the object of the present invention at a higher level, the magnetic fine particles constituting the magnetic fine powder have at least an aminosilane group and have an electric resistance of 1 × 1.
It is preferably from 0 ^{3 to} 9 × 10 ³ . 1 × electric resistance
In the case of 10 ³ or less, the presence of aminosilane groups on the surface of the magnetic fine powder particles is very sparse, so that the wettability between the feed resin and the magnetic fine powder during kneading is lowered, and the magnetic fine powder is removed from the toner particles during toner production. The body easily separates, and drum fusion due to the released magnetic fine powder easily occurs. On the other hand, when the electric resistance is larger than 9 × 10 ³ , the toner as a whole becomes high in resistance, which causes a decrease in density due to charge-up. A more preferable resistance range is 3 × 10 ^3.
Is about 5 × 10 ³ .

The content of the magnetic fine powder in the toner particles is 10% by weight from the viewpoint of suppressing the occurrence of the fog phenomenon and adjusting the true specific gravity.
Below, preferably 1 to 10% by weight, more preferably 1 to
5% by weight is good. When it is less than 1% by weight, it is difficult to suppress the occurrence of the fog phenomenon in toner particles having a weight average particle diameter of 7.5 to 9.5 μm, and when it is more than 10% by weight, the magnetic binding force is dominant. Next image density is low,
The amount of detached magnetic powder increases and drum fusion easily occurs. This is because when the content of the magnetic powder is large, the true specific gravity of the toner increases to 1.3 or more, and as described above, the toner is scattered due to the stronger centrifugal force as the developing sleeve rotates. Further, when the content of the magnetic powder is small, the true specific gravity of the toner is reduced to 1.1 or less, and the difference in specific gravity from the magnetic carrier as the two-component developer becomes too large as described above, resulting in deterioration of mixing efficiency and replenishment toner. Is one of the causes of toner scattering and fogging due to poor charging.

The toner particles of the present invention may contain wax. Examples of the waxes include paraffin wax and its derivatives, microcrystalline wax and its derivatives, Fisher Tropsch wax and its derivatives, polyolefin wax and its derivatives, carnauba wax and its derivatives, long-chain carboxylic acids and their derivatives, long-chain alcohols and their Examples include derivatives. Derivatives include oxides, block copolymers of vinyl monomers and wax, and graft modified products of vinyl monomers and wax.

The wax preferably used in the present invention is preferably a low molecular weight polypropylene wax, and the number average molecular weight (Mn) by gel permeation chromatography (GPC) is preferably 6000 to 8000. Generally, under the conventional kneading conditions, the kneading temperature immediately after the kneaded product is discharged from the kneader is an important parameter for knowing the kneading state. At a kneading temperature 15 to 30 ° C. higher than the softening point of the PP wax, the dispersibility of the wax in the binder resin is good, and in such a case, the wettability between the binder resin and the magnetic fine powder is also high. As a result, the object of the present invention can be better achieved.

The colorant used in the present invention contains at least carbon black, and dyes and other pigments can be used if necessary. Examples of colorants that are particularly preferably used as carbon black include carbon blacks such as furnace black, acetylene black, thermal, and black. Among these carbon blacks, those having a primary particle size of 15 to 30 nm, which are excellent in dispersibility in a resin, are desirable, and those having an acidity (pH 7 or less) which does not impair other raw material characteristics during toner production are desirable. . Examples of other dyes and other pigments include nigrosine dyes, carmine dyes, various basic dye acid dyes, oil dyes, anthraquinone dyes, and the like; benzidine yellow organic pigments,
Examples include quinanthrin-based organic pigments, rhodamine-based organic pigments, phthalocyanine-based organic pigments, zinc oxide, and titanium oxide. Since the toner of the present invention contains magnetic fine particles as a coloring component, a small amount of a coloring agent such as carbon black may be added, and the amount is usually 3 to 7 parts by weight per 100 parts by weight of the resin. It is possible to fully satisfy the function.

In these carbon blacks, naphthalene, acenaphthene, phenanthrene, anthracene, fluoranthene, benzo (a) anthracene, chrysene, and benzene are used as organic volatile components derived from the aromatic raw material oil during the production of carbon black. A large number of compounds having a highly reactive vinyl group in the benzene skeleton such as benzo (e) pyrene and benzo (b) fluoranthene remain and are contained. When the organic volatile component is present alone, these lead to a decrease in resin strength, a decrease in offset resistance and blocking resistance, and an unpleasant odor during fixing. The present invention is characterized in that this problem is rendered harmless by a combination of the following resins when kneading the toner.

The binder resin used in the toner of the present invention will be described below. Examples of the binder resin of the toner used in the present invention include polystyrene; poly-P-
Homopolymers of styrene substitution products such as chlorostyrene and polyvinyltoluene; styrene-P-chlorostyrene copolymers, styrene-vinyltoluene copolymers, styrene-vinylnaphthalene copolymers, styrene-acrylic acid ester copolymers , Styrene-methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl Examples thereof include styrene-based copolymers such as ketone copolymers, styrene-butadiene copolymers, styrene-isoprene copolymers and styrene-acrylonitrile-indene copolymers.
Particularly, a cross-linked styrene resin is also a preferable binder resin. In addition, other resins may be appropriately mixed. For example, as other resins; polyvinyl chloride, phenol resin, natural modified phenol resin, natural modified maleic acid resin, acrylic resin, mefryl resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy Resin, xylene resin, polyvinyl achiral, terpene resin, coumarone indene resin, petroleum-based resin and the like can be mentioned.

Comonomers for the styrene monomer in the case of producing a styrene copolymer include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate,
2-ethylhexyl acrylate, phenyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate,
Monocarboxylic acids having double bonds such as acrylonitrile, methacrylonitrile and acrylamide or substituted products thereof; dicarboxylic acids having double bonds such as maleic acid, butyl maleate, methyl maleate and dimethyl maleate and substitutions thereof Body: vinyl ester such as vinyl chloride, vinyl acetate and vinyl benzoate; ethylene olefin such as ethylene, propylene and butylene; vinyl ketone such as vinyl methyl ketone and vinyl hexyl ketone; vinyl methyl ether, vinyl ethyl ether, vinyl Vinyl ethers such as isobutyl ether are mentioned.

These vinyl monomers are used alone or in combination with the styrene monomer. A compound having two or more polymerizable double bonds is mainly used as the crosslinking agent for obtaining the crosslinked styrene resin. For example, aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; carboxylic acid esters having two double bonds such as ethylene glycol diacrylate, ethylene glycol dimethacrylate and 1,3-butanediol dimethacrylate; divinylaniline; And divinyl compounds such as divinyl ether, divinyl sulfide and divinyl sulfone; and compounds having 3 or more vinyl groups. These crosslinking agents may be used alone or as a mixture. In addition, styrene-based resin is used for gel permeation chromatography (GP
In C), the weight average molecular weight (Mw) is 15 × 10 ⁴
25 × 10 ⁴ , number average molecular weight (Mn) of 2 × 10 ³
It is 4 × 10 ³ , and the softening point is preferably 145 ° C to 165 ° C.

The styrene resin used in the present invention preferably has a residual monomer content of 200 ppm to 1000 ppm. Here, the residual monomer amount is 200
If it is less than ppm, the polymerization reaction with the organic volatile components remaining in the carbon black is not sufficient, while 1000 ppm
In the above case, many unreacted monomers remain in the produced toner, which is not preferable. Such a styrene-based resin having a large amount of residual monomer does not require a strict demonomer treatment, and thus is inexpensive in terms of cost and advantageous in terms of raw material cost. If these residual monomers were present alone,
This results in a decrease in resin strength and a problem such as a decrease in offset resistance and blocking resistance, and an offensive odor during fixing. However, at the time of the toner manufacturing process,
By heating to a melt-kneading temperature 15 ° C. to 30 ° C. higher than the softening point of the styrene-based resin, a polymerization reaction with an organic volatile component (a compound having a vinyl group in the benzene skeleton) remaining in the carbon black is caused, resulting in a low molecular weight compound. It is possible to make it harmless by polymerizing it. As described above, the feature of the present invention is that by optimizing the amount of the monomer remaining in the styrene resin, the organic volatile component in the carbon black at the time of melt-kneading the toner undergoes a thermal polymerization reaction with the residual monomer in the binder resin. It is reduced and rendered harmless by.

In the present invention, the residual monomer in the styrene resin can be quantified by thermogravimetry (TG), which is used as a weight loss during heating, such as thermogravimetry, and gas chromatography (GC). A known method such as a method using (1) can be applied. Among these, the method using GC is a particularly effective method. In the present invention, when the residual monomer in the styrene-based resin is quantified by TG, it is obtained from the heating loss observed when the sample is heated to 200 ° C. A specific example will be described below. <TG measurement conditions> Device: TGA-7, PE7700 (manufactured by Perkin Elmer) Temperature rising rate: 10 ° C / min Measurement environment: under N ₂ atmosphere

A specific example of quantifying the residual monomer in the styrene resin by using GC will be described below. <GC measurement conditions> Apparatus: GC-14A (manufactured by Shimadzu Corporation) Column: Fused silica capillary column (J & W SCI
Made by ENTIFC; size: 30m x 0.249mm,
Liquid phase: DBWAX, film thickness: 0.25 μm) Sample: 100 m using 2.55 mg DMF as an internal standard
1 l of acetone is added to make a solvent containing an internal standard. Next, 400 mg of toner is made into a 10 ml solution with the above solvent. After ultrasonically shaking for 30 minutes, leave it for 1 hour. Then, filter with a 0.5 μm filter. The amount of sample to be implanted is 4 μl. Detector: FID (split comparison: 1:20) Carrier gas: N ₂ gas Oven temperature: 70 ° C. → 220 ° C. (waiting at 70 ° C. for 2 minutes, then heating at a rate of 5 ° C./minute) Inlet temperature: 200 ℃ Detector temperature: 200 ℃ Preparation of calibration curve: DMF same as sample solution, same gas chromatograph measurement for standard sample prepared by adding target monomer to acetone solution, weight ratio of monomer to internal standard DMF / Calculate the area ratio.

In the toner of the present invention, it is preferable to use an organometallic compound as a charge control agent. Among the organometallic compounds, those containing an organic organic compound rich in vaporization and sublimation as a ligand or a counter ion are particularly useful.
As such an organometallic compound, there is an azo metal complex represented by the following general formula. Among such azo metal complexes, it is preferable to use a charge control agent containing Cr as a central metal and represented by the following structural formula (1) or structural formula (2). The charge control agent is preferably added in the range of 0.5 to 3 parts by weight with respect to 100 parts by weight of the toner.

[0032]

[Chemical 1]

[0033]

[Chemical 2]

In the toner of the present invention, the charging stability,
In order to improve developability, fluidity and durability, it is preferable to externally add inorganic fine powder to the toner particles. This is closely related to the construction of the drum cartridge in the present invention. In an ordinary cartridge, the toner collected by the cleaning member is collected by its own weight in the direction of gravity opposite to that on the photosensitive drum, and is collected in a box by a spiral member or the like. The drum cartridge of the present invention has a smaller cleaning space due to the recent tendency toward miniaturization. Therefore, the toner collected by the cleaning member is collected in the box while being pressed against the photosensitive drum. Therefore, the fusion of the magnetic fine powder on the drum becomes more remarkable.

In order to eliminate such a problem, it is necessary to improve the fluidity of the toner itself and reduce the coefficient of friction with the drum. For this reason, in the structure like the present drum cartridge, a larger amount of inorganic fine powder than usual is externally added to prevent the above problems. However, such a fine powder usually has a strong negative charging property, and excessive external addition causes one of the factors that cause the charge-up of the entire toner and a decrease in image density. Therefore, the amount of the inorganic fine powder added is preferably 0.3 to 1 part by weight based on 100 parts by weight of the toner.

Examples of the inorganic fine powder include silica fine powder, titanium oxide fine powder, and alumina fine powder. In particular, the inorganic fine powder having a specific surface area of 90 to 150 m ² / g by nitrogen adsorption measured by the BET method gives good results. Inorganic fine powder, if necessary, hydrophobicization, silicone varnish for the purpose of charge control, various modified silicone varnish, silicone oil, various modified silicone oil, silane coupling agent, silane coupling agent having a functional group, It is also preferably treated with a treating agent such as another organosilicon compound. Two or more kinds of treatment agents may be used. In particular, silica fine powder surface-treated with silicone oil is preferable.

As other additives, lubricants such as Teflon (registered trademark), zinc stearate, polyvinylidene fluoride and silicone oil particles (containing about 40% silica) are preferably used. Further, abrasives such as cerium oxide, silicon carbide, calcium titanate and strontium titanate are preferably used, and among them, strontium titanate is preferable. Further, a small amount of anti-caking agent; conductivity imparting agent such as carbon black, zinc oxide, antimony oxide, tin oxide; white fine particles and black fine particles having polarities opposite to those of toner particles may be used as a developing property improver.

In the image forming method using the toner of the present invention, it is preferable to use 1 to 10 parts by weight of the toner of the present invention as a two-component developer mixed with 100 parts by weight of the magnetic carrier described below. As the magnetic carrier used in this case, an iron powder type carrier is desirable.
This is because the clearance between the developing sleeve (developer carrier) and the doctor blade or the clearance between the developer carrier and the electrostatic image carrier (photosensitive drum) in the process cartridge suitable for the image forming method of the present invention is 1. 0m
This is because it is as wide as m or more. Such a wide clearance has an advantage that the production cost is low because the accuracy of the cartridge itself is rough. On the other hand, the ears of the developer on the developer carrying member become long, and carrier adhesion tends to occur. Further, in this cartridge, the rotating direction of the sleeve and the rotating direction of the drum are opposite to each other in order to simplify the gear arrangement of the rotating member and reduce the cost. For this reason, the developing system has a greater stress on the ears of the developer and is more likely to cause carrier adhesion. In such a developing system, for example, the ferrite carrier described in Japanese Patent Publication No. 56-52305 has a low saturation magnetization,
When carrier particles are made smaller, carrier adhesion occurs,
There is a drawback that the photoreceptor and the cleaning blade are damaged and the durability of this member is significantly shortened. Therefore, an iron powder type carrier having a stronger magnetic force is suitable for the present invention.

At present, iron powder carriers generally put into practical use are classified into the following two types according to their external shapes. One of them has an irregular shape whose shape is not fixed. As described in Japanese Examined Patent Publication No. 55-40863, this is an amorphous iron powder carrier because the raw iron powder is sintered, crushed, and classified, and the magnetic flux density in the developing magnetic field due to the shape anisotropy. Higher and harder ears, Soli
Detachment (toner peeling portion) is likely to occur in the d portion (solid black portion). Also, “cracking” and “chipping” are likely to occur during the process of transporting the developer, which damages the surface of the photoconductor and consequently deteriorates the image. Further, there are drawbacks that the flowability of the developer is poor, the deterioration of the developer is accelerated, and the torque applied to the developing roller in the process of conveyance is increased.

The other one is generally called atomized iron powder having a spherical shape or a granular shape close to a spherical shape, which is preferably used in the present invention. In this case, since the shape is close to a sphere, the irregular shaped iron powder does not have a problem and has excellent characteristics. However, since the specific surface area is smaller than that of the amorphous carrier, the charge imparting ability is lowered in the development using the small particle diameter toner as in the present invention. Therefore, a carrier specific surface area according to the specific surface area of the toner is required, and it is necessary to reduce the particle size. The carrier particle diameter suitable for the toner of the present application is preferably 80 μm or less. However, when the carrier particle diameter is 40 μm or less, the fluidity is deteriorated, which is one of the causes of problems such as poor charging and increased spent. Therefore, it is preferable that the carrier particles have a weight average particle diameter of 40 to 80 μm. The true specific gravity of the carrier is preferably 6.0 or more in order to optimize the mixing and stirring property in consideration of the difference in specific gravity from the toner of the present invention. However, if the true specific gravity exceeds 8.0, the rubbing force of the drum increases, which is one of the causes of image quality deterioration. Therefore, the true specific gravity of the carrier is preferably 6.0 to 8.0.

It is desirable to coat the magnetic carrier with a resin as an insulating film. As the resin that can be used for the coat, all the resins that have been conventionally used can be used, but a silicone resin is more preferable. As the silicone resin, silicone varnish (TSR 115, TSR 114, TSR 10 manufactured by Toshiba) is used.
2, TSR lO3, YR 3061, TSR lO,
TSR 116, TSR 117, TSR 108, TSR
10, TSR 180, TSR 181, TSR 18
7, TSR 144, TSR 165, Shin-Etsu Silicone KR 271, KR 272, KR 275, KR 28
0, KR 282, KR 267, KR 269, KR 2
11, KR 212 etc.), alkyd modified silicone varnish (Toshiba TSR 184, 185 etc.), epoxy modified silicone varnish (Toshiba TSR 194, YS)
54 etc.), polyester modified silicone varnish (Toshiba TSR 187 etc.), acrylic modified silicone varnish (Toshiba TSR 170,171 etc.), urethane modified silicone varnish (Toshiba TSR 175 etc.), reactive silicone resin (Shin-Etsu Silicone Co., Ltd.) Made KAl00
8, KBEL003, KBCl003, KBM 30
3, KBM 403, KBM 503, KBM 602,
KBM 603).

Next, a manufacturing method by melting and kneading the toner particles will be described. As the kneading machine used in the present invention, it is preferable to use an extruder for kneading in response to the recent mass production of toner. In particular, a twin-screw extruder is a preferable kneader from the viewpoint of quality stability and mass productivity. Specific examples thereof include TEM-100B (manufactured by Toshiba Machine) and PCM-87 (manufactured by Ikegai Tekko). In the present invention, in the melt-kneading step for producing toner particles, a mixture containing at least a binder resin, a colorant, magnetic fine powder and wax is produced by a kneader under the following conditions. Kneading temperature: Softening point temperature of resin and wax + 15 ° C to 3
0 ° C rotation speed: 150 to 210 rpm Supply amount: 80 to 140 kg / hr The obtained kneaded product is rolled and cooled by a conventionally known method,
Coarse crushing, fine crushing with a jet stream, and classification are carried out to obtain desired toner particles.

In the toner of the present invention, the organic volatile components in the carbon black during the melt-kneading are reduced by the thermal polymerization reaction with the residual monomer in the binder resin. A material having good dispersibility between the raw materials of the body, wax and the like and the binder resin can be obtained. Here, regarding the dispersibility of the magnetic fine powder and the wax in the toner particles, the dielectric loss of the toner tan δ
And it can be known by measuring the resistance value R. Generally, when the dispersibility of the material components in the toner is poor, t
The value of an δ is large and the resistance value is small. When the dispersibility is good, the value of tan δ is small and the resistance value R is large. However, when the dispersion is too high, the toner resistance value increases and the developability deteriorates. In the toner of the present invention, tan δ (× 10 ⁻³ ) and resistance value R (× 10
⁺⁹ ) is preferably under the following conditions. 1.5 <tan δ <4.
0 and 200 <R <350 are preferable.

The method of measuring tan δ will be described below. First, the measurement was performed using a dielectric replacement measuring device (TSR / 10T type, manufactured by Ando Electric Co., Ltd.). As a measuring method, first,
A sample for measurement of about 1.6 mm is prepared from the obtained toner by using a tablet molding machine. Next, the sample is mounted inside the solid-state electrode, and the electrode is plugged into a constant temperature bath. The measurement mode of the measuring device is set to the zero balance mode, the PATIO value is determined according to the measurement frequency, and the equilibrium operation is performed. The value of the conductance at this time is R ₀ . Further, the measurement mode is changed and the equilibrium operation is performed in the same manner as the zero equilibrium. Let Cx be the capacitance and the conductance R'at this time. Tan δ can be calculated as follows using the above measured values.

First, dielectric constant (ε ′) = Cx / C ₀ (1) Here, C ₀ is a geometrical capacitance which is a capacitance when the dielectric is replaced by air. On the other hand, the dielectric loss factor (ε ″) is calculated by the following formula: Dielectric loss factor (ε ″) = Gx / ωC ₀ (2) where ω is the angular frequency and ω = 2πf (f is the frequency Hz ) And Gx are conductances and are shown by Gx = PATIO value × (R′−R _o ). tan δ is expressed by tan = ε ″ / ε ′ (3). Substituting equations (1) and (2) into equation (3), tan δ becomes Gx / ωGx = PATIO value ×
It is represented by (R′−R _o ) / 2πfCx, and tan δ was measured by substituting each measured value. The measurement method in the present application was performed at a measurement frequency of 1 kHz, and the PATIO value corresponding thereto was 1 × 10 ⁹ .

An example of an image forming method using the toner of the present invention will be described with reference to FIG. First, a voltage is applied by the charging charger 2 to negatively charge the surface of an electrostatic charge image carrier (hereinafter, referred to as a photosensitive drum) 1, and a laser latent image forming means 3 exposes a digital latent image for image scanning. On the toner carrier (developing sleeve) 4 which is formed on the drum 1 and contains a magnet,
A developing device 7 including a doctor blade 5 as a developer layer thickness control means, a developer supply roller 6, and a stirring means 15.
The developer (two components of toner and magnetic carrier) 8 therein is electrostatically adhered, and the photosensitive drum 1 and the developing sleeve 4 come close to each other,
The latent image on the photosensitive drum 1 is reversely developed with toner. At this time, in the developing section, the conductive substrate of the photosensitive drum 1 is grounded and the developing sleeve 4 is applied with a DC bias by the bias applying means 9. When the transfer paper P is conveyed and reaches the transfer portion, the roller transfer means 10 charges the transfer paper P from the back surface (the surface opposite to the photosensitive drum 1 side) by the voltage applying means 11 to transfer the transfer paper P onto the surface of the photosensitive drum 1. The developed image (toner image) is transferred onto the transfer paper P by the roller transfer means 10.

The transfer paper P separated from the photosensitive drum 1 is
The heating and pressure roller fixing device 12 performs fixing processing to fix the toner image on the transfer paper P. The toner remaining on the photosensitive drum 1 after the transfer process is cleaned by the elastic blade 13 and collected in the collection box 14. Photosensitive drum 1 after cleaning by such cleaning means
The process starting from the charging process by the charging charger 2 is repeated. The photosensitive drum 1 has a photosensitive layer and a conductive substrate. The non-magnetic cylindrical developing sleeve 4, which is a toner carrier, rotates so as to move in the direction opposite to the surface of the photosensitive drum 1 in the developing section. Inside the developing sleeve 4, a multi-pole permanent magnet (magnet roll) which is a magnetic field generating means is arranged so as not to rotate. The developer (toner and magnetic carrier) 8 in the developing unit 7 is supplied from the developer supply roller 6 onto the surface of the non-magnetic cylinder 4, and the developing sleeve 4
The toner developer 8 is given, for example, a negative triboelectric charge by the friction between the surface of the toner and the doctor blade 5.

A DC bias may be applied to the developing sleeve 4 in the developing section by a bias means. The DC bias may be -400V to -500V. When the toner is transferred in the developing section, the toner is transferred to the electrostatic image side by the action of the electrostatic and bias on the surface of the photosensitive drum. The photosensitive drum 1 has a conductive base layer formed of a conductive metal such as aluminum and a photoconductive layer formed on the outer surface thereof as basic constituent layers, and is rotated at a predetermined peripheral speed (process speed). It The surface of the photosensitive drum 1 is charged with a predetermined polarity and potential by the charging charger 2. Next, an electrostatic charge image is formed by image exposure 3, and the electrostatic charge image is sequentially visualized as a toner image by the developing means from the developing sleeve 4.

Next, the process cartridge in the image forming apparatus of the present invention will be described. The process cartridge of the present invention is a cartridge in which at least the developing unit and the latent image holding member are individually made into a cartridge, and is configured to be attachable to and detachable from the image forming apparatus main body (for example, a copying machine, a laser beam printer, a facsimile apparatus). ing. here,
A process cartridge in which a developing means from a developing sleeve, a drum-shaped electrostatic image holding member (photosensitive drum), a cleaning means having a cleaning blade, a charging charger as a primary charging means, and the like are integrally formed is exemplified as one embodiment. It

In such an embodiment, the developing means has a doctor blade as a developer layer thickness regulating means and a developer consisting of toner and a magnetic carrier in a toner container, and the bias applying means is used during development. A developing electric field is formed between the photosensitive drum and the developing sleeve as a toner carrier by the developing bias voltage from the developing step, and the developing step is performed. In order to properly carry out this developing step,
The distance between the photosensitive drum and the developing sleeve is adjusted to 1 mm or more. In the above, the embodiment in which the four components of the developing unit, the latent image holding member, the cleaning unit and the primary charging unit are integrated into a cartridge has been described. However, in the present invention, the developing unit, the electrostatic image holding member and There is no particular limitation as long as they are separately cartridged.

[0051]

EXAMPLES The present invention will be described more specifically based on the following examples.

Example 1 (i) 100 parts by weight of binder resin (a) Styrene-n-butyl acrylate copolymer (St)
-Ac copolymerization weight ratio = 80: 20) (b) Weight average molecular weight (Mw) 200,000, number average molecular weight (Mn) 3000 (c) Softening point: 155 ° C. (d) Oxidation 0.2 KOHmg / mg (e) Residual monomer amount 500 ppm (f) Loss elastic modulus G ″ at 140 ° C .: 1.5 × 10 ⁴ dy
n / cm ²

(Ii) 3 parts by weight of magnetic fine powder (a) Weight average particle diameter R: 0.20 μm (b) Shape of magnetic fine particles: octahedron (c) σr / σs: 0.15 [−] (d) r = 4 × 10 ³ [Ω · cm] (iii) 1.5 parts by weight of negative charge control agent (a) Monoazo complex represented by the structural formula (1) (b) Primary particle diameter: 7 μm

(Iv) 2 parts by weight of wax (A) Low molecular weight polypropylene (B) Softening point: 155 ° C (C) Method of measuring softening point: DSC endothermic peak temperature (V) 6 parts by weight of carbon black (A) pH: 3 (B) Primary particle size: 30 μm

The above materials (toner formulation 1 in Table 1) were mixed with a Henschel mixer to obtain a mixture, and the obtained mixture was introduced into a twin-screw extruder (model name "PCM-65 (made by Ikegai Tekko)". , Screw rotation speed 180 (r
pm), set temperature 100 ° C, supply amount of mixture 110 kg
The mixture was melt-kneaded at / hr. The temperature of the kneaded product immediately after kneading was 180 ° C. (Production condition 1 in Table 2).

The kneaded material is coarsely crushed to 1 mm or less with a hammer mill.
Crushing the obtained coarsely crushed product using a jet stream
Finely pulverized with an air flow pulverizer to obtain a finely pulverized product. Weight of toner particles
The average particle size (D50) was 8.2 μm and the resulting toner
-The physical properties of the particles are shown in Table 3. Toner particles 100 obtained
Parts by weight, silane coupling agent and dimethyl silicone
Hydrophobic silica fine powder surface-treated with oil (BE
T specific surface area 120 m ²/ G) 0.55 parts by weight
A negative triboelectrically chargeable toner was prepared.

In order to evaluate the toner in the image forming method, a laser beam printer (trade name AR-1) which develops an electrostatic charge image by a reversal developing method having a resolution of 600 dpi is used.
60, fixing temperature 160 ° C., Sharp Co., Ltd.) was introduced into a developing device of a process cartridge as a two-component developer containing 1 to 10 parts by weight of the toner magnetic carrier and 100 parts by weight of the latter as a two-component developer. Was attached to a laser beam printer, and an image output test was performed in each environment. Further, the image quality of the latent image of dots was evaluated by the following evaluation method using a laser beam printer modified so as to have a resolution of 1200 dpi. The door
The physical properties of ner are shown in (Table 3), and the evaluation results are shown in (Table 4) .

Evaluation Method (a) Image Density Measuring Method A black part of a copy sample obtained by making three copies using an original including a black circle having a diameter of 55 mm was measured by a Macbeth densitometer and averaged. 2nd sheet (initial), 200,00
The image density of a solid black image on day 0 (20k) was measured by a Macbeth densitometer. Image density (ID) evaluation criteria 5; 1.4 or more 4; 1.3 to 1.43; 1.2 to 1.32; 1.0 to 1.21; 1.0 or less

(B) Fog Density Measuring Method A4 size white paper is previously measured for whiteness with a whiteness meter (Hunter whiteness meter, manufactured by Nippon Denshoku Industries Co., Ltd.) and the value is used as a first measurement value. Next, using a manuscript containing a white circle with a diameter of 55 mm,
The white area of the copy sample obtained by copying 3 sheets (initial) and 200,000 sheets (20k) was measured by the above-mentioned whiteness meter, and this value was used as the second measurement value. The value obtained by subtracting the value of the second measured value from the value of the first measured value is taken as the initial fog value and the fog value of 20 k.
The difference from the whiteness was determined, and the maximum value was shown. Fog density (BG) evaluation criteria 5; 0.4 or less 4; 0.6 to 0.43; 0.8 to 0.62; 1.0 to 0.81; 1.0 or more

(C) 600 dpi dot image A one-dot toner image is formed under image forming conditions capable of forming 600 dot latent images per inch, and the toner image is magnified to visually check the image quality as shown below. Graded. 5: Excellent 4; Good 3; Normal 2; Slightly bad 1; Bad (Scattering of toner is seen, or dot image shape is distorted.)

(D) Offset resistance The second sheet (initial stage) and the degree of occurrence of the 200,000th sheet (20k) were evaluated. 5: It did not occur at all. 3; Several points were observed, but there was no practical problem. 1; Many occurrences (tens of points), and there is a problem in practical use. Rank 4 is an intermediate level between Ranks 5 and 3, and Rank 2
Is an intermediate level between ranks 3 and 1. The overall evaluation was the average of the above evaluations.

(E) Blocking resistance Evaluation was made based on the degree of occurrence of the second sheet (initial) and the 200,000th sheet (20k). 5: It did not occur at all. 3; Several points were observed, but there was no practical problem. 1; Many occurrences (tens of points), and there is a problem in practical use. Rank 4 is an intermediate level between Ranks 5 and 3, and Rank 2
Is an intermediate level between ranks 3 and 1. The overall evaluation was the average of the above evaluations.

Comparative Examples 1 to 11 Various kinds of resins used in the above-mentioned Example 1 were changed (residual monomer, softening point), the addition amount of the magnetic fine powder, the average particle diameter of the toner and the like were changed. Physical properties of each toner obtained by toner formulation (Table 1) and manufacturing conditions (Table 2) are shown in (Table 3), and evaluation results are shown in (Table 4) .

[0064]

[Table 1]

[0065]

[Table 2]

[0066]

[Table 3]

[Table 4]

[0067]

INDUSTRIAL APPLICABILITY The toner of the present invention has good dispersibility between the raw materials by prescribing the amount of residual monomer in the binder resin, is excellent in offset resistance and blocking resistance, and is free from deterioration of image quality over a long period of time. It has become possible to provide toner that does not cause it. Further, as the styrene-based resin as the binder resin, a resin containing a relatively large amount of residual monomer can be used, and therefore, a cheaper styrene-based resin can be obtained in that a styrene-based resin that does not require a special demonomer treatment cost can be used. To be

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of an image forming method of an electrophotographic apparatus using the toner of the present invention.

[Explanation of symbols] 1 photosensitive drum 2 Charger 3 Laser light generation means 4 Development sleeve 5 doctor blade 6 Developer supply roller 7 Developer 8 Toner developer 9 Bias applying means 10 roller transfer means 11 Voltage applying means 12 Heat and pressure roller fixing device 13 Elastic blade 14 collection box

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identifier FI G03G 9/08 361 (72) Inventor Yasuharu Morinishi 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka (72) Inventor Takahiro Bito 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Prefecture Sharp Corporation (72) Inventor Yuichiro Takei 22-22, Nagaike-machi, Abeno-ku, Osaka City, Osaka Prefecture (56) Reference (JP) Hei 9-114193 (JP, A) JP 4-359260 (JP, A) JP 8-240933 (JP, A) JP 4-50868 (JP, A) JP 6-266159 (JP, A) Kaihei 6-161153 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 9/08-9/09 G03G 15/08

Claims (5)

(57) [Claims] 1. A toner for developing an electrostatic charge image, which is obtained by melt-kneading at least a binder resin, a colorant, an antistatic agent, and magnetic fine powder, and then finely pulverizing the mixture after cooling. The binder resin at the time of melt-kneading Removes residual monomer from 200 to 10
It is a styrene-based resin having a softening point of 145 to 165 ° C. containing 00 ppm, a coloring agent is carbon black containing at least an organic volatile component, and the softening point of the styrene-based resin at the time of melt kneading is 1 or more.
By heating to a melt kneading temperature of 5 ° C to 30 ° C higher,
The organic volatile component in the carbon black is reduced by the thermal polymerization reaction with the residual monomer in the binder resin, the weight average particle diameter is 7.5 to 10.5 μm, and the true specific gravity (g / cc) is The toner for developing an electrostatic charge image according to any one of 1.1 to 1.3. 2. A magnetic fine powder content of 1 to 10% by weight,
The electrostatic charge image developing toner according to claim 1, wherein the saturation magnetization [σs (Am 2 / kg)] of the toner under a magnetic field of 79.58 kA / m (1 K oersted) satisfies the following condition. 0.1 <σs <3.0 3. The toner has a dielectric loss [tan δ].
(× 10 ^-3)] and resistance [R (× 10 ^+9)] The toner for electrostatic image development according to claim 1 or 2 which satisfies the following condition. 1.5 <tan δ <4.0, 200 <R <35
0 As 4. The method of claim 1 or the two-component developer obtained by mixing a magnetic carrier to the toner for electrostatic image development according to any one of 3, charge adheres to the developer担侍surface of the magnet is installed Then, the image forming method is characterized in that the toner is adhered to the electrostatic charge image on the electrostatic charge image carrier and developed. 5. The image forming apparatus according to claim 4, wherein the electrostatic charge image holding member and the developer bearing member holding the toner have a clearance of 1 mm or more and are used in an image forming apparatus incorporated as a detachable cartridge in the image forming apparatus main body. Image forming method.