JP2001350293A - Electrostatic charge image developing toner, developer for electrostatic charge image development, device for image formation and method for image formation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner, developer, device for image formation and method for image formation by which decrease in the image density is not caused in any environment in electrostatic charge image development without controlling special development conditions. SOLUTION: An electrostatic charge image developing toner having toner particles containing a binder resin, a charge controlling agent which is a chromium complex salt compound expressed by general formula (I) and magnetic fine powder as a coloring material and having 7.5 to 10.5 μm weight average particle size and 1.1 to 1.3 g/cm3 absolute specific gravity is used as the single component developer for the device for image formation. The chromium complex salt compound has 6 to 10 μm primary particle size and included by 0.2 to 1 pt.wt. to 100 pts.wt. of the binder resin in the toner particles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a toner for forming a toner image by developing an electrostatic image in an image forming method such as electrophotography, a developer using the toner, and an image using the developer. The present invention relates to a forming apparatus and a method.

[0002]

2. Description of the Related Art In recent years, functions of an image forming apparatus using an electrophotographic technique, such as a copying machine and a laser beam printer, have become more versatile, and there is a demand for higher definition and higher image quality. Such an image forming apparatus tends to use a toner having a finer particle diameter. When the particle size of the toner particles is reduced, high definition of the image can be achieved, but the fluidity of the image is reduced, and a physical defect that the bulk density is reduced occurs.

[0003] In general, when the fluidity of the toner is reduced, the rise of the charge is poor, causing toner scattering and image fogging. Further, when the bulk density is reduced, the weight of the toner to be filled in a certain volume is reduced, so that it is necessary to increase the capacity of the toner filling hopper and the collected toner container. Therefore, in order to improve fluidity, a large amount of a fluidizing agent is added. The fluidizing agent usually has a strong negative charging property, and when added in a large amount, increases the charging property of the entire toner, so that a decrease in image density often poses a problem.

[0004]

In order to solve such a problem, strongly charged toner is forcibly developed by changing development conditions such as a development potential rise and a development electric field strength rise. However, such a change in the development conditions leads to an increase in the cost of the machine body, and thus there is a demand for an essential improvement of the developer itself.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a toner for developing an electrostatic charge image which does not cause a decrease in image density due to an increase in charge caused by the addition of a large amount of a fluidizing agent in each environment without special developing conditions. An object of the present invention is to provide a developer using the toner, and an image forming apparatus and a method using the developer.

[0006]

According to the present invention, there is provided an electrostatic image developing toner having toner particles containing a binder resin, a charge controlling agent and a magnetic fine powder as a coloring material, wherein the toner particles are: A weight average particle size of 7.5 to 10.5 μm, and a true specific gravity of 1.1 to 1.3 g / cm ³ ;
The charge control agent is a chromium complex salt compound represented by the general formula (I), and is a toner for developing an electrostatic image.

[0007]

Embedded image

[Wherein X is Cl, Br, SO ₂ NH ₂ ,
Represents SO ₂ CH ₃ , SO ₂ C ₂ H ₅ , wherein A has 8 to 16 carbon atoms
Represents an alkylammonium which may be interrupted by one linear or branched oxygen atom. ]

According to the present invention, by using a charge control agent having excellent chargeability, it is possible to suppress an increase in charge amount due to addition of a large amount of a fluidizing agent without setting special development conditions.
Since the charge amount of the toner as a whole can be optimized, it is possible to provide an electrostatic image developing toner that does not cause a decrease in density under each environment.

The present invention also provides the chromium complex compound,
The primary particle diameter is 6 to 10 μm. According to the present invention, the chargeability of the toner can be effectively controlled.

Further, the present invention provides the chromium complex compound,
It is characterized in that the toner particles are contained in the toner particles in a ratio of 0.2 to 1 part by weight based on 100 parts by weight of the binder resin.

According to the present invention, an appropriate amount of charge can be imparted to the toner even when a fluidizing agent is added, and a decrease in image density can be prevented.

[0013] Further, the present invention provides a method wherein the toner particles include BET.
The specific surface area measured by the method is 90 to 150 m ² / g
Wherein the inorganic fine powder is externally added.

According to the present invention, particularly when the cleaning member is used in an image forming apparatus provided with a cleaning means for pressing the photosensitive member against the photosensitive member to remove the residual toner, the fusion of the magnetic powder to the photosensitive drum is effectively prevented. can do.

Further, the present invention is characterized in that the inorganic fine powder is contained in an amount of 1 to 2 parts by weight based on 100 parts by weight of the toner particles.

According to the present invention, it is possible to prevent the fusion of the magnetic powder and the decrease in the image density due to the charge-up.

Further, the present invention is characterized in that the inorganic fine powder is a silica fine powder treated with silicone oil. ADVANTAGE OF THE INVENTION According to this invention, while making hydrophobic, charging property can be controlled.

Further, the present invention is characterized in that the inorganic fine powder has a primary particle diameter of 10 to 20 nm.

According to the present invention, the fusion of the magnetic powder to the photosensitive drum can be effectively prevented.

In the present invention, the magnetic fine powder preferably comprises 79.
Residual magnetization σr [Am ² / kg] and saturation magnetization σs [Am ² / k] under a magnetic field of 58 kA / m (1 k Oersted)
g] satisfies the relationship of 0.05 <σr / σs <0.25.

According to the present invention, fogging can be favorably prevented particularly in a high-temperature and high-humidity environment, and a decrease in image density due to endurance copying can be prevented, thereby maintaining the image density.

Further, according to the present invention, the magnetic fine powder is octahedral particles having at least an aminosilane group on the surface, and has a specific electric resistance of 1 × 10 ^{3 to} 9 × 10 ³ Ω · c.
m.

According to the present invention, the octahedral shape can prevent rotation in the dispersion process and achieve high dispersion. The specific electric resistance is small, the wettability is reduced, and the drum is easily fused. It is possible to prevent the image density from being lowered due to the large resistance due to charge-up.

The present invention is also characterized in that the magnetic fine powder is contained in the toner particles in an amount of 1 to 10% by weight.

According to the present invention, it is possible to prevent the occurrence of fogging, a reduction in image density, and the occurrence of drum fusion.

Further, the present invention is characterized in that the magnetic fine powder has a weight average particle diameter of 0.05 to 0.30 μm.

According to the present invention, it is possible to avoid a difference in magnetic binding force and an increase in variation in magnetic binding force.

In the present invention, the binder resin may be one or more selected from the group consisting of a styrene polymer, a styrene copolymer, a styrene-acrylate copolymer and a styrene-methacrylate copolymer. Styrene resin. According to the present invention, an image having a high image density can be formed.

In the present invention, the styrene resin has a number average molecular weight of 2 × 10 ³ to 4 × 10 ³ and a weight average molecular weight of 15 × 10 ^{4 to} 25 × 10 ^4. I do. According to the present invention, an image having a high image density can be formed.

Further, the present invention is characterized in that the binder resin has an acid value of less than 1.0 KOHmg / g. According to the present invention, an image having a high image density can be formed.

The present invention is also characterized in that the binder resin has a softening point of 145 to 165 ° C. According to the present invention, the dispersibility of the toner material in the binder resin can be improved.

Further, in the invention, it is preferable that the toner particles have a particle diameter of 79.
The saturation magnetization under a magnetic field of 58 kA / m (1 K Oersted) is 0.1 to 3.0 [Am ² / kg]. According to the present invention, drum fusion can be effectively prevented.

The present invention is also characterized in that the toner particles have a dielectric loss of 1.5 × 10 ^{−3 to} 4.0 × 10 ⁻³ .

According to the present invention, the dispersibility of the toner material is appropriately increased and the developability is not reduced.

Further, in the invention, it is preferable that the toner particles have a specific electric resistance of 200 × 10 ^{9 to} 350 × 10 ⁹ Ω · m.

According to the present invention, the dispersibility of the toner material is appropriately increased and the developability is not reduced.

The present invention is also characterized in that the toner particles contain 1 to 3 parts by weight of a low molecular weight polypropylene wax. According to the present invention, the dispersibility of the wax in the binder resin can be improved.

The present invention is also characterized in that the low molecular weight polypropylene wax has a number average molecular weight of 6,000 to 8,000. According to the present invention, the dispersibility of the wax in the binder resin can be improved.

The present invention is also characterized in that the low molecular weight polypropylene wax has a softening point of 145 to 165 ° C. According to the present invention, the dispersibility of the wax in the binder resin can be improved.

The present invention is a developer for developing an electrostatic image, which is a one-component developer comprising the toner for developing an electrostatic image.

According to the present invention, by using a charge control agent having excellent chargeability, it is possible to suppress an increase in charge amount due to the addition of a large amount of a fluidizing agent without setting special development conditions.
Since the charge amount of the toner as a whole can be optimized, it is possible to provide a developer for developing an electrostatic image that does not cause a decrease in density under each environment.

According to the present invention, there is provided an image forming apparatus comprising means for developing an electrostatic latent image with the developer for developing an electrostatic image.

According to the present invention, it is possible to suppress an increase in the charge amount due to the addition of a large amount of a fluidizing agent and optimize the charge amount of the toner as a whole without setting special developing conditions. An image forming apparatus can be provided which does not cause a decrease in density in the image forming apparatus.

The present invention contains a binder resin, a chromium complex compound represented by the general formula (I) as a charge controlling agent, and a magnetic fine powder as a coloring material, and has a weight average particle size of 7.5 to 7.5.
10.5 μm and a true specific gravity of 1.1 to 1.3 g /
An image forming method comprising a step of developing using a one-component developer composed of an electrostatic image developing toner having toner particles of cm ³ .

[0045]

Embedded image

[Wherein X is Cl, Br, SO ₂ NH ₂ ,
Represents SO ₂ CH ₃ , SO ₂ C ₂ H ₅ , wherein A has 8 to 16 carbon atoms
Represents an alkylammonium which may be interrupted by one linear or branched oxygen atom. ]

According to the present invention, it is possible to suppress an increase in the charge amount due to the addition of a large amount of a fluidizing agent and optimize the charge amount of the toner as a whole without setting special developing conditions. An image forming method can be provided which does not cause a decrease in the density of the image.

[0048]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An electrostatic image developing toner according to an embodiment of the present invention (hereinafter also simply referred to as "toner")
Contains at least a binder resin, a charge control agent (CCA) and magnetic fine powder as a coloring component, and, if necessary, toner particles containing additives such as a wax and a coloring agent. An additive is externally added.

The weight average particle diameter of the toner particles is 7.5.
〜10.5 μm is preferred. In order to faithfully reproduce an electrostatic latent image in units of one dot on the photosensitive drum, the weight particle size of the toner needs to be 10.5 μm or less.
However, when the weight average particle diameter is 7.5 μm or less, when used in the image forming method of the present invention described later, the toner scattering increases. This is because as the weight particle size of the toner decreases, the number of particles that are not governed by the electrostatic force increases. When the clearance between the developing sleeve and the photosensitive drum is as narrow as 1 mm or less, the above-mentioned toner scattering is small. However, in the process cartridge of the present invention described below, the clearance becomes 1 mm or more, so that the weight particle diameter of the toner decreases. Becomes more remarkable, and toner scattering increases.

Even when an external additive is externally added to the toner particles, the weight average particle size of the toner usually shows substantially the same value as the weight average particle size of the toner particles. The particle size can be regarded as the weight average particle size of the toner.

The weight average particle size of the toner particles is measured by a Coulter counter method. Examples of a measuring device based on the Coulter counter method include a Coulter counter T
A-II or Coulter Multisizer (manufactured by Coulter Inc.) is used. About 1% NaCl aqueous solution is prepared using primary sodium chloride as the electrolytic aqueous solution. For example, ISOTON-II (manufactured by Coulter Corporation) can be used.

The measuring method is as follows.
0.1 to 5 ml of a surfactant, preferably an alkylbenzenesulfonate, is added as a dispersant in ~ 150 ml;
Further, 2 to 20 mg of a measurement sample is added. The electrolytic aqueous solution in which the measurement sample is suspended is subjected to a dispersion treatment using an ultrasonic disperser for about 1 to 3 minutes.
Using a 00 μm aperture, the volume and number of toner particles are measured, and the volume distribution and number distribution are calculated. From the calculated volume distribution and number distribution, the weight-based weight average particle diameter (D4) of the toner particles is determined.

As a channel, 2.00 or more and 2.5
Less than 2 μm, 2.52 or more and less than 3.17 μm, 3.17
Not less than 4.00 μm, not less than 4.00 and less than 5.04 μm, not less than 5.04 and less than 6.35 μm, and not less than 6.35 and 8.
Less than 00 μm, 8.00 or more and less than 10.08 μm, 1
0.08 or more and less than 12.70 μm, 12.70 or more 1
6.00 μm or less, 16.00 or more and less than 20.20 μm, 20.20 or more and less than 25.40 μm, 25.40 or more and less than 32.00 μm, and 32.00 or more and 40.3 or more
Using 13 channels of less than 0 μm, particle size of 2.00 μm
m or more and less than 40.30.

The true specific gravity of the toner particles is 1.1 to 1.3 g.
/ Cm ³ . True specific gravity of the toner particles, becomes smaller than 1.1 g / cm ^3, background fogging increases and becomes greater than 1.3 g / cm ^3, dominant next image density decrease magnetic binding force, the drum due to falling of the magnetic powder This is because fusion is likely to occur. The true specific gravity of the toner particles was measured using a pycnometer cell.

It is preferable to use an organometallic compound as the charge control agent. Among the organometallic compounds, an organometallic compound containing an organic compound having high vaporization and sublimation properties as a ligand or a counter ion is particularly useful. As such an organometallic compound, there is an azo-based metal complex. Among the azo-based metal complexes, it is more preferable to use a charge control agent represented by the following general formula (I) containing Cr as a central metal.

[0056]

Embedded image

[Wherein X is Cl, Br, SO ₂ NH ₂ ,
Represents SO ₂ CH ₃ , SO ₂ C ₂ H ₅ , wherein A has 8 to 16 carbon atoms
Represents an alkylammonium which may be interrupted by one linear or branched oxygen atom. ]

The charge control agent represented by the general formula (I) has excellent charge ability, and can provide an effective charge to the toner even when added in a small amount. Considering the toner charge due to the addition of the fluidizing agent, the charge control agent is preferably added in the range of 0.2 to 1 part by weight based on 100 parts by weight of the toner.

The magnetic fine powder is 79.58 kA / m
(1k Oersted) magnetic field under a magnetic field
The relationship between [Am ² / kg] and the saturation magnetization σs [Am ² / kg], that is, the magnetic force (σr / σs) of the magnetic fine powder is 0.
Preferably it is less than 25.

As a developing method in which the toner of the present invention is preferably used, a magnet roll is provided in a developing sleeve which is a carrier for the toner and the developer, and the toner and the developer are held by the magnet roll, and triboelectric charging is performed on a carrier. And developing the electrostatic image on the photosensitive drum as the electrostatic image holding member with the charged toner.
In such a developing method, the above-mentioned weight average particle diameter of 7.
When toner particles having a size of 5 to 10.5 μm are used, fogging in a high-temperature and high-humidity environment, and a phenomenon in which the solid black density is reduced at the time of durability tend to occur.

These problems are caused by the magnetic force (σr) of the magnetic fine powder.
/ Σs) can be effectively solved. By applying magnetic force to the toner, it is possible to satisfactorily prevent the occurrence of fogging caused by a decrease in the amount of triboelectric charge of the toner in a high-temperature and high-humidity environment, and to prevent the image density from decreasing and maintain the image density. .

When a magnetic fine powder having a magnetic force (σr / σs) of 0.25 or more is used, the magnetic restraining force does not work effectively. The phenomenon of low solid black density tends to occur. If the magnetic force (σr / σs) of the magnetic fine powder is less than 0.05, the magnetic constraining force becomes dominant, and the image density tends to decrease in all the above-mentioned environments, which is not preferable. The magnetic force (σr / σs) of the magnetic fine powder is more preferably in the range of 0.1 to 0.2. Magnetic properties are VSMP-
Using an external magnetic field of 79.5 using 1-10 (manufactured by Toei Industry Co., Ltd.)
It was measured at 8 kA / m.

As the magnetic fine powder, iron, cobalt,
A magnetic metal oxide containing an element such as nickel, copper, magnesium, manganese, aluminum, or silicon can be used. 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 depending on the physical shearing force. When the toner is used for a toner, the magnetic force is not uniform, and the magnetic restraining force can differ depending on the direction of the magnetic field. Absent. When the weight average particle diameter is larger than 0.30 μm, a small number of magnetic fine powders are uniformly dispersed and used in the toner according to the present invention as described later. Is not preferred because the variation of

Examples of the shape of the magnetic fine particles constituting the magnetic fine powder include an octahedron, a hexahedron, and a sphere. An octahedral shape, which is more susceptible to physical shearing force, is preferred in order to prevent rotation in the dispersion process and achieve high dispersion, since image density and fog latitude (permissible range) can be widened.

The magnetic fine particles constituting the magnetic fine powder are as follows:
Further, in order to satisfy the object of the present invention at a higher level, it is preferable that at least an aminosilane group is present and the specific electric resistance r is 1 × 10 ³ <r <9 × 10 ³ [Ω · cm]. . When the specific electric resistance is 1 × 10 ³ [Ω · cm] or less, the presence of aminosilane groups on the surface of the magnetic fine particles is extremely sparse, so that the wettability between the binder resin and the magnetic fine powder during kneading of the toner material is reduced. And the magnetic fine powder is easily detached from the toner particles in the production of the toner, and the detached magnetic fine powder easily causes the fusion of the magnetic powder to the photosensitive drum. The specific electric resistance is 9 × 10 ³ [Ω ·
cm], the resistance of the entire toner increases, causing a reduction in image density due to charge-up.
A more preferable range of the specific electric resistance is 3 × 10 ^{3 to} 5 × 10 ^3.
[Ω · cm].

The magnetic fine powder contains 1 to 1 in the toner particles.
It is preferably contained at 0% by weight. When the amount is less than 1% by weight, it is difficult to suppress the fogging phenomenon in the toner particles having a weight average particle diameter of 7.5 to 10.5 μm. When the amount is more than 10% by weight, the magnetic binding force is dominant. As a result, the image density is lowered, and the amount of the magnetic powder that drops off increases, so that the magnetic powder is likely to be fused to the photosensitive drum.

More preferably, the content of the magnetic fine powder in the toner particles is 1 to 5% by weight.

When the content of the magnetic fine powder is large, the true specific gravity of the toner increases, and the toner receives a stronger centrifugal force as the developing sleeve rotates. Since the centrifugal force is increased by the combined force of the magnetic force and the electrostatic force, the toner is scattered. In addition, when the content of the magnetic fine powder is small, the true specific gravity of the toner becomes small and the difference in specific gravity with the magnetic carrier becomes too large, thereby lowering the mixing efficiency and causing toner scattering and fogging due to poor charging of the replenishment toner. It is one of the causes.

Examples of the wax include paraffin wax and its derivatives, microcrystalline wax and its derivatives, Fischer-Tropsch wax and its derivatives, polyolefin wax and its derivatives, carnauba wax and its derivatives, long-chain carboxylic acid and its derivatives, and long waxes. Chain alcohols and derivatives thereof. Derivatives include oxides, block copolymers of vinyl monomers and waxes, and graft modified products of vinyl monomers and waxes.

Among the above waxes, a low molecular weight polypropylene wax is more preferable, and a number average molecular weight (M) determined by gel permeation chromatography (GPC).
n) is preferably 6,000 to 8,000. This is because the dispersibility with the binder resin during kneading can be improved. For the same reason, it is preferable that the low molecular weight polypropylene wax is contained in an amount of 1 to 3 parts by weight based on 100 parts by weight of the toner particles.

The wax, especially the polypropylene wax, has good dispersibility in the binder resin at the time of kneading the toner material at a temperature 15 to 30 ° C. higher than its softening point. Under the kneading conditions when the toner material is kneaded using the kneader, the temperature of the kneaded material immediately after kneading when the kneaded material in which the toner material is kneaded is discharged from the kneader is an important parameter for knowing the kneading state. . Generally, when the temperature of the kneaded material immediately after kneading is set to a kneading state of 180 ° C., the softening point of the wax is preferably 145 to 165 ° C. In this kneaded state, the wettability between the binder resin and the magnetic fine powder is also improved, so that the fusion of the magnetic powder to the photosensitive drum can be more effectively prevented as described above.

Examples of the binder resin include styrene-substituted homopolymers such as polystyrene, poly-p-chlorostyrene and polyvinyltoluene, styrene copolymers, polyvinyl chloride, phenol resins, naturally-modified phenol resins, Naturally modified maleic acid resin, acrylic resin,
Examples include methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy resin, xylene resin, polyvinyl butyral, terpene resin, cumarone indene resin, and petroleum resin. Crosslinked styrenic resins are also preferred binder resins.

Examples of the styrene copolymer include a styrene-p-chlorostyrene copolymer, a styrene-vinyltoluene copolymer, a styrene-vinylnaphthalene copolymer,
Styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer Polymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer and styrene-
Acrylonitrile-indene copolymer and the like can be mentioned.

As comonomers for the styrene monomer of the styrene copolymer, acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, methacrylic Monocarboxylic acid having a double bond such as acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile and acrylamide or a substitute thereof, maleic acid, butyl maleate, maleic acid Dicarboxylic acids having a double bond such as methyl and dimethyl maleate and substituted products thereof, vinyl esters such as vinyl chloride, vinyl acetate and vinyl benzoate, ethylene, propylene and butylene Ethylenic olefins, such as, vinyl ketones, and vinyl methyl ether such as vinyl methyl ketone and vinyl hexyl ketone, vinyl ethers such as vinyl ethyl ether and vinyl isobutyl ether. These vinyl monomers are used alone or in combination with the styrene monomer.

As the crosslinking agent, a compound having two or more polymerizable double bonds is mainly used. 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, Examples include divinyl compounds such as divinyl ether, divinyl sulfide and divinyl sulfone, and compounds having three or more vinyl groups. These crosslinking agents are used alone or in combination.

Further, the styrene resin has a weight average molecular weight (Mw) determined by gel permeation chromatography (GPC) of from 15 × 10 ^{4 to} 25 × 10 ⁴ ,
Number average molecular weight (Mn) by GPC is 2 × 10 ³ or more 4
It is preferably not more than × 10 ³ . When Mw and Mn are within the above ranges, a decrease in image density can be prevented.

The oxidation of the resin is related to its surface functional group, and the more acidic groups, the greater the oxidation, and the chargeability of the resin tends to be on the negative electrode side. However, these acidic groups act on the azo-based metal complex to cause deactivation of the active ingredient. Therefore, the acid value of the binder resin is 1.0 KOHm
The addition amount is preferably less than g / g. Further, the binder resin preferably has a softening point of 145 to 165 ° C. in relation to the temperature of the kneaded material, similarly to the aforementioned wax.

Examples of the coloring agent include dyes, pigments and carbon black. Specific examples thereof include dyes such as nicrosin dye, carmine dye, various basic dyes, acid dyes, oil dyes and anthraquinone dyes. And a benzidine-based yellow organic pigment, a quinantrine-based organic pigment, a rhodamine-based organic pigment, a phthalocyanine-based organic pigment, zinc oxide and titanium oxide. More preferably used colorants include carbon black such as furnace black, acetylene black and thermal black.

The carbon black has a primary particle diameter of 15 to 30 nm which is excellent in dispersibility in a resin, and has an acidity of pH 7 or less which does not impair the characteristics of other toner materials during toner production. Carbon black is preferred. Since magnetic fine particles as a coloring component are added to the toner, the addition amount of carbon black may be small, and the function can be sufficiently satisfied with 3 to 7 parts by weight based on 100 parts by weight of the binder resin. It is possible.

It is preferable that an inorganic fine powder is externally added to the toner particles to improve the charge stability, developability, fluidity and durability of the toner. In a normal cartridge, the toner collected by the cleaning member is collected by its own weight in the direction of gravity opposite to the photosensitive drum, and is collected in a box by a spiral member or the like. The cleaning space of the drum cartridge according to the present invention has been reduced due to the recent trend of miniaturization. Due to the miniaturization, the toner collected by the cleaning member is collected in a box while pressing the photosensitive drum, so that the fusion of the magnetic powder to the photosensitive 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.

In the structure such as the drum cartridge according to the present invention, the friction coefficient is reduced by externally adding a larger amount of inorganic fine powder than usual, thereby preventing the magnetic powder fusion as described above. . However, such fine powder usually has a strong negative charging property, and excessive external addition causes charge-up of the entire toner, which is one of the factors that lower the image density. The amount of the inorganic fine powder to be added is preferably 1 to 2 parts by weight of the inorganic fine powder with respect to 100 parts by weight of the toner in consideration of imparting fluidity to the small particle diameter toner.

The primary particle diameter of the inorganic fine powder is set at 10 to prevent the magnetic powder from being fused to the photosensitive drum more effectively.
It is preferably about 20 nm.

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 measured by nitrogen adsorption by the BET method favorably prevents the fusion of the magnetic powder.
If necessary, the inorganic fine powder may be used for the purpose of hydrophobization and charge control, such as silicone varnish, various modified silicone varnishes,
It is also preferable to be treated with a treating agent such as silicone oil, various modified silicone oils, a silane coupling agent, a silane coupling agent having a functional group, and other organosilicon compounds. Particularly, silica fine powder surface-treated with silicone oil is preferable. Two or more treatment agents may be used in combination.

In addition to the wax, charge control agent and colorant, other additives contained in the toner particles include:
For example, lubricants such as Teflon, zinc stearate and polyvinylidene fluoride, silicone oil particles containing about 40% silica are used. Abrasives such as cerium oxide, silicon carbide, calcium titanate and strontium titanate are preferably used, among which strontium titanate is a particularly preferred abrasive.
A small amount of an anti-caking agent, a conductivity-imparting agent such as carbon black, zinc oxide, antimony oxide and tin oxide, and a developing property improver made of white fine particles and black fine particles having a polarity opposite to that of the toner particles may be used.

Next, a method for producing a toner will be described.
As a kneading machine used for the production of toner, it is preferable to knead using an extruder in response to recent mass production of toner. In particular, a twin-screw extruder is a preferred kneader from the viewpoint of quality stability and mass productivity. Specific examples include TEM-100B (manufactured by Toshiba Machine) and PCM
-87 (made by Ikegai Iron Works) and the like.

In the melt-kneading step for forming the toner particles, a kneaded product is obtained by kneading the toner material mixture containing the binder resin, the magnetic fine powder and the wax by the above-mentioned kneader under the following conditions. Kneading temperature: softening point temperature of binder resin or wax + 15
℃ -30 ℃ Number of rotations: 150-210 rpm Supply amount: 80-140 kg / hr

The obtained kneaded material is subjected to rolling and cooling, coarse pulverization, fine pulverization by a jet stream and classification by a conventionally known method,
Toner particles are obtained.

The dispersibility of the magnetic fine powder and wax in the obtained toner particles can be known by measuring the dielectric loss (tan δ) and the resistance value R of the toner particles. Generally, when the dispersibility of the toner material in the toner particles is poor, the value of the dielectric loss (tan δ) is large, and the resistance value R is small. When the dispersibility is good, the value of the dielectric loss (tan δ) is small and the resistance value R is large. However, if the dispersion becomes too high, the resistance R
Rise to cause a decrease in developability. In the toner particles, 1.5 <tanδ <4.0 and 200 <R <3
50 is preferred.

The dielectric loss (tan δ) was measured using a dielectric loss measuring device (TRS-10T: manufactured by Ando Electric Co., Ltd.). As a measurement method, first, a sample for measurement of about 1.5 mmφ is prepared from the obtained toner particles using a tablet molding machine. Next, the sample is mounted inside the solid electrode, and the electrode is plugged into a thermostat. The measurement mode of the measurement device is set to the zero balance mode, the PATIO value is determined according to the measurement frequency, and the balance operation is performed. The value of the conductance at this time is defined as Ro. Further, the measurement mode is changed and the balance operation is performed in the same manner as the zero balance. The capacitance at this time is Cx, and the conductance is R1.

Tan δ can be determined as follows using the measured values. Assuming that the geometric capacitance, which is the capacitance when the dielectric is replaced with air, is Co, the dielectric constant (ε1) is obtained from the dielectric constant (ε1) = Cx / Co (1). Frequency ω is represented by ω = 2πf by frequency f (Hz), and conductance Gx is represented by Gx = P
Since it is expressed by ATIO value × (R1−Ro), the dielectric loss factor (ε2) is obtained from the dielectric loss factor (ε2) = Gx / ωCo (2). tan δ is expressed by tan δ = ε2 / ε1 (3), and by substituting equations (1) and (2) into equation (3), tan δ becomes Gx / ωCx = PATIO value × (R1-Ro) ) / 2πfCx (4), and tan δ was determined by substituting each measured value. Measured at a frequency of 1 kHz, and the PATIO
The value was 1 × 10 ⁻⁹ .

The toner particles have a particle size of 79.58 kA / m
It is preferable that the saturation magnetization σs [Am ² / kg] of the magnetic fine powder under a magnetic field of (1 k Oe) is 0.1 <σs <3.0. This is because the clearance between the developing sleeve and the doctor blade of the process cartridge according to the present invention is as wide as 1.0 mm or more. Such a wide clearance has an advantage that the production cost is not required because the accuracy of the process cartridge itself may be rough. On the other hand, the spikes of the developer become longer and drum fusion is likely to occur. In the process cartridge according to the present invention, the rotational direction of the sleeve and the rotational 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 drum fusion. Therefore, the process cartridge of the present invention is required to have high saturation magnetization and strong magnetic force.

An external additive containing the inorganic fine powder was externally added to the toner particles whose dispersibility was evaluated as described above by a conventionally known method to obtain a toner.

Next, an example of an image forming method using the obtained toner will be described. FIG. 1 is a sectional view showing an example of the configuration of an image forming apparatus according to the present invention. FIG. 2 is an enlarged sectional view showing a part of FIG. The image forming apparatus includes a charging unit having a charger 1, an exposure unit having a laser unit 3, a developing unit 6 and a photosensitive drum 2.
And a transfer unit having a roller transfer unit,
A cleaning unit having cleaning means.

In the charging section, a voltage is applied by the charging charger 1, and the surface of the photosensitive drum 2 as an electrostatic image carrier is negatively charged. A developing sleeve, which is a toner carrying member that forms a digital latent image on the surface of the photosensitive drum 2 by image scanning by exposure to laser light from the laser unit 3 and includes a doctor blade 14 and a magnet roll 4 that is a magnet. The latent image is reversal-developed with the toner in the developer 7 of the developing device 6 provided with the developing device 5. In the developing section, the conductive base of the photosensitive drum 1 is grounded, and a DC bias is applied to the developing sleeve 5 by bias applying means. When the transfer paper 8 is conveyed to the transfer section, the transfer paper 9 is charged by the voltage application means from the back side of the transfer paper opposite to the photosensitive drum 2 side by the roller transfer means 9, thereby developing on the surface of the photosensitive drum. A toner image, which is an image, is transferred onto transfer paper by a transfer charger. The transfer paper 8 separated from the photosensitive drum 2 is subjected to a fixing process in a heating and pressing roller fixing device in order to fix a toner image on the transfer paper 8 by a heating roller and a pressing roller.

The toner remaining on the photosensitive drum 2 after the transfer step is cleaned by an elastic cleaning blade 12 and collected in a collection box. After the cleaning by the cleaning unit, the photosensitive drum 2 repeats the process starting from the charging process by the charger 1 as the charging unit.

The photosensitive drum 2 has a photosensitive layer and a conductive substrate. A non-magnetic cylindrical developing sleeve 5 serving as a toner carrier rotates so as to advance in a direction opposite to the surface of the photosensitive drum 2 in the developing section. Inside the developing sleeve 5,
A magnet roll composed of a multi-pole permanent magnet, which is a magnetic field generating means, is arranged so as not to rotate. The toner 7 in the developing device 6 is applied on the non-magnetic cylindrical surface of the developing sleeve 5,
The toner 7 is given, for example, a negative triboelectric charge by friction with the carrier.

The DC bias applied by the bias means in the developing section may be -400 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 2.

The photosensitive drum 2 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 process speed of a predetermined peripheral speed. You. The surface of the photosensitive drum is charged to a predetermined polarity and potential by a charging charger. Next, an electrostatic image is formed by development exposure, and the electrostatic image is sequentially visualized as a toner image by a developing unit.

Next, the process cartridge according to the present invention will be described. The process cartridge according to the present invention is configured such that at least the developing means and the electrostatic image holder are individually formed as a cartridge, and is detachably mounted on a main body of an image forming apparatus such as a copying machine, a laser beam printer, and a facsimile machine. I have.

As shown in FIG. 2, a developing device 6 as a developing means, a photosensitive drum 2 as a drum-shaped electrostatic image holding member,
A process cartridge 13 in which a cleaning unit having a cleaning blade 12 and the charger 1 as a primary charging unit are integrated is exemplified. In the process cartridge 13, the developing means has a doctor blade 14 as a developer layer thickness controlling means and toner in a toner container, and uses the toner. At the time of development, the developing means applies a developing bias voltage from a bias applying means to the photosensitive drum. A predetermined electric field is formed between the developing sleeve as a toner carrier and the developing process is performed. In order to suitably carry out this developing step, the distance between the photosensitive drum and the developing sleeve and the distance between the doctor blade and the developing sleeve are adjusted.

As described above, the embodiment in which the four components of the developing device, the electrostatic image holding member, the cleaning device, and the primary charging device are integrally formed as a process cartridge has been described. The process cartridge may be one in which the developing means and the electrostatic image holder are separately made into a cartridge.

(Examples) The present invention will be described more specifically based on the following examples.

Various toners were manufactured according to the following toner prescription. First, toner particles were obtained using a binder resin, a magnetic fine powder, a charge control agent, a wax and carbon black.

The binder resin is a styrene-n-butyl acrylate copolymer (copolymerization weight ratio = 80: 20) having a weight average molecular weight (Mw) of 200,000, a number average molecular weight (Mn) of 3,000, Softening point 155 ° C and acid value 0.2K
100 parts by weight of resin with OH mg / mg were used.

The magnetic fine powder has an aminosilane group, a weight average particle size of 0.20 μm, and σr / σs = 0.1
5. Three parts by weight of a magnetic fine powder having a specific electric resistance of 4 × 10 ³ Ω · cm and octahedral magnetic fine particles were used.

As the charge control agent (CCA), a negative charge control agent having a primary particle diameter of 7 μm and a monoazo complex represented by the general formula (I) was used in an amount shown in Table 1 below.

As the wax, 2 parts by weight of polypropylene having a softening point of 155 ° C. and a number average molecular weight (Mn) of 6,000 to 8,000 were used. In addition, the softening point of the wax was measured by a DSC endothermic peak temperature.

As carbon black, a primary particle diameter of 3
6 parts by weight of carbon black having 0 μm and pH 3 were used.

[0109]

[Table 1]

The above materials were mixed with a Henschel mixer while changing the amount of the charge control agent added as described above to obtain five mixtures corresponding to toner formulations 1 to 5. The obtained mixture was introduced into a twin-screw extruder (model name “PCM-65”: Ikegai Iron Works), set temperature 100 ° C., screw rotation speed 80 rpm, and mixture supply amount (discharge amount) 110
The mixture was melt-kneaded at kg / hr. The temperature of the kneaded material immediately after kneading was 180 ° C. The kneaded product was coarsely pulverized to 1 mm or less by a hammer mill, and the obtained coarsely pulverized product was finely pulverized by a collision type air flow pulverizer using a jet stream to obtain a finely pulverized product. The physical properties of the obtained toner particles are shown in Table 2 below.

As described above, the true specific gravity of the toner was measured using a pycnometer cell, and the saturation magnetization was measured as VSMP.
−1-10 (manufactured by Toei Kogyo Co., Ltd.), dielectric loss (ta
nδ) was measured using TRS-10T (manufactured by Ando Electric Co., Ltd.).

100 parts by weight of the obtained toner particles and BE
Table 1 of hydrophobic silica fine powder having a T specific surface area of 120 m ² / g and a primary particle diameter of 15 nm, and having been surface-treated with a silane coupling agent and dimethyl silicone oil.
Was added to prepare toners of toner formulations 1 to 5 having negative triboelectric charging properties.

Evaluation results of an image forming test performed using the toner obtained as described above as a one-component developer in the image forming apparatus shown in FIGS. 1 and 2 are shown in Table 3 below. It is shown in FIG. A toner is introduced into a developing device of a process cartridge for a laser beam printer (trade name: AR-160: manufactured by Sharp Corporation) for developing an electrostatic image by a reversal developing method having a resolution of 600 dpi, and the process cartridge is mounted on the laser beam printer. And an image-drawing test was performed under each environment. The image formed in the image formation test was evaluated for image density, fogging degree, drum fusion, image quality, and toner consumption by the following measurement methods.

(A) Method of Measuring Image Density Initially (2 to 4)
20K (200,000-200,002)
Each of the three sheets was copied, and the image density (ID) of the obtained solid black image was measured with a Macbeth densitometer, and the average of the three sheets was evaluated in the following five grades. 5: 1.4 or more 4: 1.3 or more and less than 1.4 3: 1.2 or more and less than 1.3 2: 1.0 or more and less than 1.2 1: less than 1.0

(B) Fog density measurement method The whiteness of A4 size white paper before image formation is measured in advance by a whiteness meter (Hunter whiteness meter, manufactured by Nippon Denshoku Industries Co., Ltd.), and the value is measured as a first value. Measured value. Next, three copies are made using a document including a white circle having a diameter of 55 mm, the white portion of the obtained copy sample is measured by the above-mentioned whiteness meter, and the average value is taken as a second measured value. The value obtained by subtracting the value of the second measurement value from the first measurement value was defined as the fog value (BG), and the evaluation was made in the following five stages. Fog values were measured initially and at 20K. 5: Less than 0.4 4: 0.4 or more and less than 0.6 3: 0.6 or more and less than 0.8 2: 0.8 or more and less than 1.0 1: 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 enlarged and visually evaluated in five steps. did. 5: Excellent 4: Good 3: Normal 2: Slightly bad 1: Bad (spattering of toner is observed and the shape of the dot image is distorted)

(D) Toner Consumption After performing 20,000 sheets of endurance copying using an A4 size original having a black solid ratio of 6%, the toner consumption in the developing device before and after the endurance copying was measured. It was rated on a scale. 5: 25 g / 1000 sheets or less 4: 25 g / 1000 sheets or more and less than 30 g / 1000 sheets 3: 30 g / 1000 sheets or more and less than 35 g / 1000 sheets 2: 35 g / 1000 sheets or more and less than 40 g / 1000 sheets 1: 40 g / 1000 sheets or more The average value of each of the above evaluations was calculated and used as a comprehensive evaluation.

[0118]

[Table 2]

[0119]

As described above, according to the present invention, by using a charge control agent having excellent chargeability, it is possible to suppress an increase in charge amount due to the addition of a large amount of a fluidizing agent without setting special development conditions. Since the charge amount of the toner as a whole can be optimized, it is possible to provide a toner for developing an electrostatic image and a developer for developing an electrostatic image, which do not cause a decrease in density under each environment.

Further, according to the present invention, by using the toner and the developer, an increase in the charge amount due to the addition of a large amount of a fluidizing agent is suppressed without setting special developing conditions, and the charge amount as the whole toner is reduced. Since the optimization can be performed, it is possible to provide an image forming apparatus and an image forming method that do not cause a decrease in density under each environment.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of a configuration of an image forming apparatus according to the present invention.

FIG. 2 is an enlarged sectional view showing a part of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Charging means 2 Photoreceptor drum 5 Developing sleeve 12 Cleaning blade 13 Process cartridge 14 Doctor blade

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) G03G 9/08 374 G03G 9/08 325 375 361 (72) Inventor Takahiro Bito 22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka No. 22 F-term in Sharp Corporation (reference) 2H005 AA02 AA03 AA06 AA08 CA04 CA22 CA25 CA26 CB13 DA02 EA01 EA02 EA03 EA05 EA06 EA07 EA10 FA06

Claims (24)

[Claims] 1. An electrostatic image developing toner having toner particles containing a binder resin, a charge controlling agent and magnetic fine powder as a coloring material, wherein the toner particles have a weight average particle diameter of 7.5 to 7.5. 10.5μm
And a true specific gravity of 1.1 to 1.3 g / cm ³ , wherein the charge control agent is a chromium complex compound represented by the general formula (I), toner. Embedded image [Wherein X is Cl, Br, SO ₂ NH ₂ , SO ₂ CH ₃ ,
It represents SO ₂ C ₂ H _5, A represents a linear or branched one alkyl ammonium be interrupted by oxygen atoms of 8 to 16 carbon atoms. ] 2. The toner according to claim 1, wherein the chromium complex compound has a primary particle diameter of 6 to 10 μm. 3. The binder resin according to claim 1, wherein the chromium complex compound is a binder resin.
2. The electrostatic image developing toner according to claim 1, wherein the toner is contained in the toner particles at a ratio of 0.2 to 1 part by weight based on 0 part by weight. 4. The electrostatic image development according to claim 1, wherein an inorganic fine powder having a specific surface area of 90 to 150 m ² / g measured by a BET method is externally added to the toner particles. For toner. 5. The electrostatic image developing toner according to claim 4, wherein the inorganic fine powder is contained in an amount of 1 to 2 parts by weight based on 100 parts by weight of the toner particles. 6. The electrostatic image developing toner according to claim 4, wherein the inorganic fine powder is a silica fine powder treated with silicone oil. 7. The inorganic fine powder has a primary particle diameter of 10 to 10.
5. The toner according to claim 4, wherein the thickness of the toner is 20 nm. 8. The magnetic fine powder according to claim 7, wherein the magnetic fine powder is 79.58 kA / m.
(1k Oersted) magnetic field under a magnetic field
[Am ² / kg] and saturation magnetization σs [Am ² / kg]
2. The electrostatic image developing toner according to claim 1, wherein a relationship of 0.05 <σr / σs <0.25 is satisfied. 9. The magnetic fine powder is an octahedral particle having at least an aminosilane group on the surface, and has a specific electric resistance of 1 × 10 ^{3 to} 9 × 10 ³ Ω · cm. The toner for developing an electrostatic image according to claim 8, wherein 10. The toner according to claim 1, wherein the magnetic fine powder contains
2. The composition according to claim 1, wherein the content is from 10 to 10% by weight.
The toner for developing an electrostatic image according to the above. 11. The electrostatic image developing toner according to claim 1, wherein the magnetic fine powder has a weight average particle diameter of 0.05 to 0.30 μm. 12. The binder resin is one or more styrene-based resins selected from the group consisting of styrene polymers, styrene copolymers, styrene-acrylate copolymers, and styrene-methacrylate copolymers. The toner for developing an electrostatic image according to claim 1, wherein the toner is a resin. 13. The styrenic resin has a number average molecular weight of 2 × 10 ³ to 4 × 10 ³ and a weight average molecular weight of 15 × 10 ^{4 to} 25 × 10 ^4. 12. The toner for developing an electrostatic image according to item 11. 14. The binder resin has an acid value of 1.0 KOH.
2. The toner according to claim 1, wherein the amount is less than mg / g. 15. The binder resin has a softening point of 145 to 1.
2. The toner according to claim 1, wherein the temperature is 65 [deg.] C. 16. The toner particles have a particle size of 79.58 kA /
^2. The electrostatic image developing toner according to claim 1, wherein the saturation magnetization under a magnetic field of m (1 K Oersted) is 0.1 to 3.0 [Am2 / kg]. 17. The toner particles having a dielectric loss of 1.
2. The toner for developing an electrostatic image according to claim 1, wherein the toner content is 5 × 10 ^{−3 to} 4.0 × 10 ⁻³ . 18. The toner particles having a specific electric resistance of 20
2. The electrostatic image developing toner according to claim 1, wherein the toner has a value of 0 × 10 ^{9 to} 350 × 10 ⁹ Ω · m. 19. The toner according to claim 1, wherein the toner particles contain 1 to 3 parts by weight of a low molecular weight polypropylene wax. 20. The toner according to claim 19, wherein the low molecular weight polypropylene wax has a number average molecular weight of 6,000 to 8,000. 21. The toner for developing an electrostatic image according to claim 19, wherein the low molecular weight polypropylene wax has a softening point of 145 to 165 ° C. 22. A developer for developing an electrostatic image, comprising a one-component developer comprising the toner for developing an electrostatic image according to claim 1. Description: 23. An image forming apparatus, comprising: means for developing an electrostatic latent image with the developer for developing an electrostatic image according to claim 22. 24. It contains a binder resin, a chromium complex salt compound represented by the general formula (I) as a charge control agent, and a magnetic fine powder as a coloring material, and has a weight average particle diameter of 7.5 to 10.
5 μm and a true specific gravity of 1.1 to 1.3 g / cm ³
An image forming method comprising the step of developing using a one-component type developer composed of an electrostatic image developing toner having toner particles. Embedded image [Wherein X is Cl, Br, SO ₂ NH ₂ , SO ₂ CH ₃ ,
It represents SO ₂ C ₂ H _5, A represents a linear or branched one alkyl ammonium be interrupted by oxygen atoms of 8 to 16 carbon atoms. ]