JP3101480B2 - Electrostatic image developing toner and method of manufacturing the same - 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 visualizing an electrostatic latent image in an image forming method such as electrophotography and electrostatic recording, and a method for producing the same.

[0002] In electrophotography, a photoconductive substance is generally used to form an electric latent image on a photoreceptor by various methods, and then the latent image is developed using a toner. Accordingly, a method of transferring a toner image to a transfer material such as paper and then fixing the toner image to the transfer material by various methods to obtain a copy.

[0003] In general, toners are classified into dry toners and wet toners. Solvent evaporation in wet toner,
Due to problems such as recovery and odor, dry toners have become the mainstream in recent years.

[0004] Dry toner is a powder, but it is necessary for the toner particles to have many functions in order to form a toner image accurately. For example, chargeability, transportability, fixability, coloring power, storage stability, and the like. Therefore, the toner is prepared as a mixture of various raw materials.

[0005] As a method for producing a dry toner, a pulverization method,
Examples include a polymerization method and an encapsulation method. In general, the crushing method is dominant. As a method for producing a toner by a pulverization method, a binder resin for fixing to a material to be transferred, various colorants for giving a color as a toner, and also a charge control agent, a magnetic substance, a release agent, etc. Pre-mix the ingredients and then
In a kneading device such as a kneader, extruder, or roll mill, melt and knead by applying shearing force while heating.
After cooling and solidifying the kneaded material, the material is coarsely pulverized to prepare a coarsely pulverized material, and then the coarsely pulverized material is finely pulverized to an appropriate particle size as a toner using a fine pulverizing device such as a jet mill. Thereafter, classification is performed by various classifiers as necessary, and the particle size is adjusted to a particle size distribution capable of exhibiting sufficient performance as a toner. Further, if necessary, a fluidity improver, a lubricant, an abrasive, etc. are dry-mixed and used as a toner. 2
When used as a component developer, various magnetic carriers and toner are mixed to prepare a developer, which is then used for image formation.

In the toner production process by the pulverization method, the dispersion state of various raw materials in the toner particles in the toner is substantially determined by the premixing process and the kneading process of the raw materials.
As a manufacturing apparatus used for the pre-mixing, a planetary stirring type mixing apparatus such as a Nauter mixer or a blade stirring type mixing apparatus such as a Henschel mixer is generally used, and a mixture prepared by these apparatuses is melt-kneaded. There are various types of kneaders, and especially in the case of mass production as of today, an extruder capable of continuous kneading is usually used.

In recent years, copiers and printers (for example, LB
(P, LED printers, etc.), the performance required of the toner is becoming more severe with the improvement of the performance of the image forming apparatus. Even if an attempt is made to obtain a high-performance toner, a satisfactory toner is not necessarily obtained in the above-described conventional processes, for example, in the case of fine dispersion of a colorant, wetting of a colorant and a binder resin, and dispersion of other internal additives. Often not. These variances,
If the wetting or the like is insufficient, the toner results in a decrease in image density, instability of performance in each environment, and contamination of a developing sleeve and a carrier.

Further, recently, from the viewpoint of ecology, contact transfer means such as a transfer roller is used in a step of transferring a toner image on a photosensitive member to a transfer material in order to suppress the generation of ozone in a copying machine or a printer. It is becoming. In the transfer means using the contact transfer means, since "transfer dropout" as shown in FIG. 12 is likely to occur, toner without "transfer dropout" is expected, and efficient production of the toner is expected. The way is long-awaited.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a toner for developing an electrostatic image with improved performance by improving the dispersion of raw materials constituting the toner and a method for producing the toner.

It is a further object of the present invention to provide a toner for developing an electrostatic image in which the composition ratio of raw materials constituting the toner is stable and a method for producing the toner.

It is another object of the present invention to provide a static toner which has no segregation of raw materials constituting the toner, has good developability, has good durability, has little fog, has good reproducibility of fine dots, and has good environmental characteristics. An object of the present invention is to provide a toner for developing a charge image and a method for producing the toner.

It is a further object of the present invention to provide a toner for developing an electrostatic charge image which causes less contamination on a developing sleeve and a carrier, and a method for producing the toner.

Further, an object of the present invention is to provide a "transfer missing".
It is an object of the present invention to provide an efficient method for producing a toner in which toner is less likely to occur.

[0014]

Specifically, the present invention provides (A) resin particles carrying or containing inorganic fine powder, (B) binder resin particles, and (C) a colorant. Premixing to prepare a mixture, melt kneading the mixture to obtain a kneaded product, cooling the kneaded product to obtain a colored resin solid, pulverizing the colored resin solid to obtain a pulverized product, The present invention relates to a toner for developing an electrostatic image, comprising toner particles obtained by classifying a pulverized product.

Further, the present invention provides a method for preparing a mixture by premixing (A) resin particles carrying or containing inorganic fine powder, (B) binder resin particles, and (C) a colorant. Is melt-kneaded to obtain a kneaded product, the kneaded product is cooled to obtain a colored resin solid, the colored resin solid is pulverized to obtain a pulverized product, and the pulverized product is classified to form toner particles. And a method for producing a toner for developing an electrostatic image.

As described above, in the toner production method using the pulverization method, the raw materials to be used are pre-mixed by a mixing device that performs planetary rotation such as a Nauter mixer or a rotary blade type mixing device such as a Henschel mixer. Then, melt kneading is performed. In the melt kneading step, kneading is generally performed using an extruder in response to the recent mass production of toner. The extruder is
It is an extruder having a single-screw or twin-screw, and can be continuously kneaded, so that it is suitable and useful for continuous production in toner production.

Generally, the dispersion of raw materials in the production of toner is not necessarily limited only by the dispersing ability of the kneader. In the production of toners using various kinds of raw materials, there is a limit in the dispersing ability of the kneading device itself. For example, in an extruder, because it flows continuously,
Naturally, the residence time is limited, and the short residence time can be a cause of insufficient dispersion. Furthermore, even if the residence time is made as long as possible, there is a limit to the dispersion ability of the apparatus main body. Pre-mixing compensates for this, and the quality of pre-mixing also affects the dispersion of raw materials. However, in the pre-mixing method as described above, since the raw materials are not dispersed microscopically, even if the pre-mixing and kneading conditions are devised, a sufficiently satisfactory dispersion of the raw materials may not be obtained. is there.

In the pre-mixing, fine raw materials such as a colorant may adhere to the wall surface of an apparatus used for mixing, and a mixture having an optimum ratio of the raw materials constituting the toner may not be obtained.

Further focusing on the particle size of the raw material,
In general, in general, the smaller the particle size of the raw material, the better the dispersion and the like should be. However, in practice, the cohesive force between the raw material particles is increased, and there is a tendency that sufficient dispersion during pre-mixing cannot be obtained. The finer the particles, the easier it becomes to contain air, and it becomes difficult to obtain a sufficient dispersion during kneading.

In the present invention, in order to solve such a problem, as shown in FIG. 1 or 2, in the pre-mixing, resin particles carrying or containing inorganic fine powder are added to the raw material.

In particular, by incorporating resin particles to which inorganic fine powder is externally added into the raw material, the dispersibility of the raw material during pre-mixing is improved. By mixing the resin particles having the inorganic fine powder on the surface, it is possible to prevent the fine particles of the colorant, charge control agent and binder resin constituting the raw material from adhering to the wall surface of the mixing machine, and furthermore, the mutual mixing of the raw material. Can be improved. This is because the inorganic fine powder externally added to the resin particles is dispersed in the raw material, improves the flowability of the whole mixture, suppresses the adhesion of the raw material to the wall surface, and furthermore, the resin particles having good flowability make the mixing machine easier. It is considered that the dispersion of the raw materials was improved by scraping off the raw materials attached to the wall surfaces and the blades, and the mixing ratio was stabilized.

The resin particles to which the inorganic fine powder is externally added are:
1 to 50% by weight based on the raw material, more preferably 2 to 4% by weight
It is preferable to contain 0% by weight. When the content is less than 1% by weight, the above-mentioned effects are hardly observed. On the other hand, when the content exceeds 50% by weight, the amount of air contained during mixing becomes excessive, and the dispersion of the raw materials is deteriorated, and the offset resistance and the like of the toner tend to be deteriorated.

The components of the resin particles to which the inorganic fine powder used in the present invention is externally added are preferably substantially the same as the components constituting the toner obtained by the present invention. If the components differ greatly, problems such as image fogging may occur. Therefore, it is preferable to use toner particles as the resin particles.

In the present invention, the toner may be a magnetic toner or a non-magnetic toner, but the effect is particularly effective in the case of a magnetic toner. Although the reason is not clearly understood, when manufacturing magnetic toner, the difference in specific gravity between the magnetic iron oxide and the binder and other materials that make up the magnetic toner is large, and non-magnetic materials that mix materials of similar specific gravity are mixed. The degree of dispersion tends to be worse than in the case of toner. When magnetic toner particles to which the inorganic fine powder of the present invention is externally added are added to this system, magnetic toner particles having a specific gravity between the specific gravity of the magnetic iron oxide and the specific gravity of the material such as a binder are interposed therebetween. And
In addition, it is considered that the mutual dispersion of the raw materials is improved by the inorganic fine powder improving the fluidity of the entire system.

The content of the inorganic fine powder used in the present invention is from 0.05 to 8.0% by weight, more preferably from 0.2 to 6.0% by weight, based on the weight of the toner particles. If the content is less than 0.05% by weight, the effect of addition is difficult to obtain, while if it exceeds 8.0% by weight, the fixability and the like tend to deteriorate.

When the obtained toner and inorganic fine powder are mixed and used as a developer, the inorganic fine powder used in the present invention is preferably of the same type or a similar material to the above inorganic fine powder.

The toner particles used in the present invention can be used in a form hardened to a certain size.

The toner particles having an inorganic fine powder used in the present invention include a copying machine and a laser beam printer (LB).
It is possible to use the toner recovered from P),
By using the recovered toner as a raw material, it is possible to greatly contribute to cost reduction of toner and global environmental protection.

In the present invention, as shown in FIG. 1, in the pre-mixing, the raw material contains resin particles carrying or containing inorganic fine powder and the fine powder separated in the classification step in a total amount of 2 to 60. %, More preferably 5 to 40% by weight.

By adding a fine powder to the raw materials, an appropriate load can be applied at the time of pre-mixing to further improve the dispersibility.

Further, the ratio of the resin particles carrying or containing the inorganic fine powder to the fine powder obtained by the classification is preferably in the range of resin particle: fine powder = 1: 20 to 20: 1. If the ratio of the resin particles carrying or containing the inorganic fine powder to the fine powder is smaller than 1:20, the fluidity of the entire raw material mixture tends to decrease during pre-mixing. Conversely, if the total content of the resin particles and the fine powder exceeds 53% by weight and the ratio of the resin particles is greater than 20: 1, the amount of air contained in the pre-mixing becomes excessive, and Dispersion tends to worsen.

The fine powder separated in the classification step used in the present invention can be used as it is, but has an average diameter of 0.05 mm to 5 mm, more preferably 0.1 mm to 2 mm.
It may be used in a form molded into mm.

One of the main objects of this is to improve the dispersion of the constituent material by applying a load at the time of pre-mixing by having particles having a large particle diameter in the constituent material. If the average diameter is smaller than 0.05 mm, the load applied during pre-mixing may be weak. On the other hand, when the average diameter is larger than 5 mm, the load at the time of pre-mixing is too large and the heat generation in the mixer is large, and the raw materials may be granulated and the dispersion may be deteriorated.

The components of the fine powder used in the present invention are preferably substantially the same as the components constituting the toner obtained by the present invention. If the components are significantly different, problems such as image fogging may occur.

The molding of the fine powder separated in the pulverizing / classifying step can be easily carried out by using a commercially available apparatus using heat and pressure.

The average value of the diameter is determined by the following method.

The molded product of the fine powder was photographed using an optical microscope or an electron microscope at a magnification such that 150 to 350 particles could be accommodated in the field of view, and any 100 on the photograph were selected, the diameter was measured using calipers, and the average was measured. The value obtained is taken as the average diameter.

As the binder resin of the toner according to the present invention,
Polystyrene; a styrene-substituted homopolymer such as polyvinyl toluene; styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer,
Styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-dimethylaminoethyl acrylate copolymer, styrene-methyl methacrylate copolymer,
Styrene-ethyl methacrylate copolymer, styrene-
Butyl methacrylate copolymer, styrene-dimethylaminoethyl methacrylate copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer,
Styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-maleic acid copolymer, styrene-
Styrene copolymers such as maleic ester copolymers; polymethyl methacrylate, polybutyl methacrylate, polyvinyl acetate, polyethylene, polypropylene, polyvinyl butyral, silicone resin, polyester resin, polyamide resin, epoxy resin, polyacryl resin, rosin , Modified rosin, temper resin, phenol resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, paraffin wax, carnauba wax and the like. These can be used alone or in combination.
In particular, styrene-based copolymers and polyester resins are preferred in terms of development characteristics, fixability, and the like. The binder resin preferably has a number average particle size of 10 to 1000 μm.

As the colorant, a known dye or pigment can be used. For example, carbon black, lamp black, ultramarine, nigrosine dye, aniline blue, phthalocyanine black, phthalocyanine green, Hansa Yellow G, rhodamine 6G lake, chrome yellow, quinacridone, benzine yellow, rose bengal, triallylmethane dye, monoazo dye pigment , Disazo dyes and pigments,
And anthraquinone dyes. These dyes and pigments can be used alone or in combination.

The colorant preferably has a secondary particle having a number average particle size of 3 μm or less (preferably 1 μm or less).

When the colorant is a dye or a pigment, it is preferably used in an amount of 2 to 20 parts by weight based on 100 parts by weight of the binder resin.

When a magnetic toner is obtained according to the present invention, the toner may also serve as a colorant, but contains a magnetic material. Examples of the magnetic material contained in the magnetic toner include iron oxides such as magnetite, γ-iron oxide, ferrite, and iron-rich ferrite; metals such as iron, cobalt, and nickel; or these metals and aluminum, cobalt, copper, and lead. , Magnesium, tin, zinc, antimony, beryllium, bismuth, cadmium, calcium,
Examples include alloys with metals such as manganese, selenium, titanium, tungsten, and vanadium, and mixtures thereof.

These ferromagnetic materials have a number average particle size of 0.1.
To 1 μm, preferably 0.1 to 0.5 μm, and more preferably 0.1 to 0.3 μm. The amount contained in the magnetic toner is preferably 20 to 200 parts by weight, more preferably 50 to 150 parts by weight, based on 100 parts by weight of the resin component.

A hydrocarbon wax or an ethylene olefin polymer may be used together with a binder resin as a fixing aid in the toner of the present invention.

The ethylene-based olefin homopolymer or ethylene-based olefin copolymer includes polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, polyethylene skeleton And the like. In the above-mentioned copolymer, those containing 50 mol% or more (more preferably, 60 mol% or more) of an olefin monomer are preferable.

The toner of the present invention may optionally contain a charge control agent. In the case of a negatively chargeable toner, a metal complex salt of a monoazo dye; a negative charge control agent such as a metal complex salt of salicylic acid, alkylsalicylic acid, dialkylsalicylic acid or naphthoic acid is used.

In the case of a positively chargeable toner, a positive charge control agent such as a nigrosine compound or an organic quaternary ammonium salt is used.

The inorganic fine powder used in the present invention includes:
For example, fine silica powder, fine titanium oxide powder, fine alumina powder and the like can be mentioned. As the inorganic fine powder, one having a BET specific surface of 50 to 400 m ² / g by a nitrogen gas adsorption method is preferable. Among them, silica fine powder is particularly preferred,
Among them, those subjected to a hydrophobic treatment are more preferable. In the hydrophobizing treatment, a coupling agent such as a silane coupling agent and an organosilicon compound such as silicone oil which are usually used can be used alone or in combination. Among them, those subjected to hydrophobic treatment with silicone oil are most preferable.

In the present invention, a general kneading method can be used in the kneading step following the pre-mixing. In particular,
Among them, an extruder system capable of continuous kneading is preferable.

The ratio of the length (L) to the diameter (D) of the screw (kneading shaft) of the extruder used is expressed as L / D =
In the case where the fine particles are used in the range of 17 to 50, the dispersion of the raw material is improved when the silica fine powder hydrophobized with silicone oil is present in the raw material of the toner. FIG. 4 shows a schematic view of the screw of the extruder.

The reason for this is that in the extruder-type kneading, the residence time is short, and the silicone oil of the silica fine powder treated with the silicone oil is dispersed in the raw material in the short residence time, and the slipperiness between the raw material particles is improved. It is considered that the dispersion of the raw materials is improved in a short time.

The hydrophobization is performed by chemically treating with an organic silicon compound or the like which reacts or physically adsorbs with the inorganic fine powder. As a preferable method, a method of treating an inorganic fine powder with a silane coupling agent, or simultaneously with a treatment with a silane coupling agent, with an organosilicon compound such as silicone oil may be mentioned. The silicone oil is preferably contained in an amount of 1 to 35 parts by weight per 100 parts by weight of the inorganic fine powder. When the amount of the silicone oil is less than 1 part by weight, the effect of adding the silicone oil is small, and when the amount exceeds 35 parts by weight, the secondary particle diameter of the inorganic fine powder is undesirably large.

In the production method of the present invention, the inorganic fine powder treated with the silicone oil can be uniformly contained in the toner particles. Accordingly, in the image forming method using the contact transfer unit as shown in FIG.
When a toner image having the character “A” shown in FIG. 12 is formed on a photosensitive drum and the toner image is transferred to a transfer material, “transfer missing” as shown in FIG. 12 may occur. In the toner obtained by the method, it is possible to favorably prevent or suppress the occurrence of “missing during transfer”.

The method for producing the toner of the present invention will be specifically described with reference to the accompanying drawings.

In FIG. 1, in the pre-mixing step, binder resin particles and a colorant are essential components as toner raw materials, and a charge control agent and an anti-offset agent are carried or contained as optional components. Dry-mixed with resin particles. For the mixing, a mixing apparatus such as a Henschel mixer shown in FIG. 3 for mixing while applying a shearing force due to rotation of the upper stirring blade and the lower stirring blade to the powder is preferably used.

The inorganic fine powder is previously mixed with resin particles (for example, a weight average particle diameter of 4 to 20 μm) and externally added to the surface of the resin particles, so that the average particle diameter is 100 mμ or less (preferably 70 mμ or less). Can be present on the surface of the resin particles in the form of fine secondary particles. As a result, the inorganic fine powder can be uniformly contained in the toner particles. Since the inorganic fine powder has a strong cohesive force, if it is directly mixed with the toner raw material without being mixed with the resin particles in advance, a considerable amount of coarse secondary particles of the inorganic fine powder of about 70 μm or more is added to the mixed system. Since it is present, it is extremely difficult to uniformly include the inorganic fine powder in the toner particles.

The average particle diameter of the secondary particles of the inorganic fine powder on the surface of the resin particles is determined by taking an enlarged photograph (for example, 20,000 times) of the resin particles with an electron microscope,
The particle size can be measured by randomly selecting 00 to 200 particles and measuring the particle size.

In the pre-mixing, the colorant may be blended in a proportion of 2 to 150 parts by weight, inorganic fine powder of 0.1 to 5 parts by weight, and resin particles of 1 to 50 parts by weight per 100 parts by weight of the binder resin particles. It is preferable in that it is efficiently and uniformly dispersed.

The mixture prepared by the pre-mixing is then kneaded while being heated by a melt kneader such as an extruder.

The kneaded material is then discharged onto, for example, a conveyor belt, cooled on the conveyor belt, and the cooled kneaded material is roughly pulverized by a pulverizer such as a cutter mill or a hammer mill.

The coarsely pulverized product is supplied to, for example, a classification and fine pulverization step shown in FIG.

In FIG. 5, reference numeral 1 denotes a multi-divider classifier such as an elbow jet classifier (manufactured by Nippon Steel Mining Co., Ltd.) utilizing the Coanda effect, and classifies the classified powder classified by the first classifier 9 into a multi-divider classifier. Is classified into fine powder, medium powder and coarse powder.

In FIG. 5, the classifying and pulverizing system comprises a three-divided classifier 1, fixed feeders 2a and 2b, fixed feeder 10,
A vibration feeder 3, a collecting cyclone 4, a collecting cyclone 5, a collecting cyclone 6, a collecting cyclone 7, a crusher 8,
The first classifier 9 is formed by connecting communication means.

In this apparatus, the coarsely pulverized product is introduced into the first classifier 9 via the quantitative feeder 2, and the classified powder from which the coarse powder region has been removed is passed through the collection cyclone 7 to the quantitative feeder 1.
0, and then introduced into the three-divided classifier 1 via the feeder nozzle 16 via the vibrating feeder 3. The coarse powder particle group classified by the first classifier 9 is
After being finely pulverized, it is again introduced into the first classifier 9 together with the newly input pulverized raw material. At the time of introduction into the three-segment classifier 1, the pulverized material is reduced to 50 to 300 using the suction force of the collecting cyclones 4, 5, and / or 6.
Suction is introduced at a flow rate of m / sec. The case of suction introduction is preferable because the sealing property of the apparatus system is not strictly required as compared with the pressure introduction.

Since the size of the classification area of the classifier 1 is usually [10 to 50 cm] × [10 to 50 cm], the pulverized material can be instantaneously divided into three or more types of particle groups in 0.1 to 0.01 seconds or less. Can be classified. The three-divided classifier 1 divides the powder into coarse powder (particles having a specified particle size or more), medium powder (particles having a specified particle size), and fine powder (particles having a specified particle size or less). Thereafter, the coarse powder is returned to the fixed quantity feeder 2b through the discharge conduit 11 via the collection cyclone 6.

The intermediate powder is discharged out of the system via the discharge conduit 12, collected by the collection cyclone 5, and collected to be a toner product 51. The fine powder is discharged out of the system via the discharge conduit 13 and collected by the collecting cyclone 4, then collected as fine powder 41 having a specified outside diameter, and supplied to the premixing step. The collecting cyclones 4, 5, and 6 use the nozzle 16
And serves as a suction depressurizing means for introducing suction into the classification area via the.

By passing the exhaust gas discharged from the upper part of the first classifier 9 through the bag filter 30, fine powder discharged from the first classifier 9 is collected. The fine powder collected by the bag filter may be supplied to the premixing step.

As the crusher 3, fine crushing means such as an impact crusher and a jet crusher can be used. Examples of the impact-type pulverizer include a turbo mill manufactured by Turbo Kogyo Co., Ltd., and examples of the pulverizer using a jet include a supersonic jet mill PJM-I manufactured by Nippon Pneumatic Industries Co., Ltd., and a micron jet manufactured by Hosokawa Micron Co., Ltd.

An example of the first classifier 9 is an airflow classifier.

The intermediate powder obtained in the classification step can be used as toner particles as it is, but the inorganic fine powder or hydrophobic inorganic fine powder described above is externally added and used as a toner.

An external additive other than the inorganic fine powder may be used in the toner of the present invention, if necessary.

For example, a charging auxiliary, a conductivity-imparting agent, a fluidity-imparting agent, an anti-caking agent, a release agent for fixing with a hot roll,
Resin fine particles and inorganic fine particles used as lubricants and abrasives.

An example of an image forming apparatus used for image formation when the toner of the present invention is a magnetic toner will be described.

A preferred specific example of the image forming apparatus will be described with reference to FIG.

The surface of the OPC photosensitive member 603 is negatively charged by the primary charger 611, a digital latent image is formed by image scanning by exposure 605 with a laser beam, and a urethane rubber elastic blade 609 provided in the counter direction is provided. The latent image is reversibly developed with a one-component magnetic developer 613 having a silica fine powder hydrophobized with silicone oil and a magnetic toner in a developing device 601 having a developing sleeve 606 containing a magnet 615. In the developing section, between the conductive substrate of the photosensitive drum 603 and the developing sleeve 606, an alternating bias, a pulse bias and / or a DC bias are applied by a bias applying unit 612. When the transfer paper P is conveyed and arrives at the transfer section, the electrostatic transfer means 604 carries out corona charging from the back surface (opposite to the photosensitive drum side) of the transfer paper P, thereby forming a developed image (toner) on the photosensitive drum surface. Image) is electrostatically transferred onto the transfer paper P. The transfer paper P separated from the photosensitive drum 603 is subjected to fixing processing for fixing a toner image on the transfer paper P by a heating / pressing roller fixing device 607.

The one-component developer remaining on the photosensitive drum after the transfer step is removed by a cleaning unit 614 having a cleaning blade 608. After the cleaning, the photosensitive drum 603 is neutralized by erase exposure 619,
The process starting from the charging process by the primary charger 611 is repeated again.

The electrostatic image carrier (photosensitive drum 3) has a photosensitive layer and a conductive substrate, and moves in the direction of the arrow. A non-magnetic cylindrical developing sleeve 606 serving as a toner carrier rotates in the developing section so as to advance in the same direction as the surface of the electrostatic image holding member.
Inside the non-magnetic cylindrical developing sleeve 606, a multi-pole permanent magnet 615 (magnet roll) as a magnetic field generating means is arranged so as not to rotate. The one-component insulating developer 613 in the developing device 601 is applied on a non-magnetic cylindrical surface, and the magnetic toner particles are given, for example, a negative triboelectric charge by friction between the surface of the developing sleeve 606 and the magnetic toner particles. . More elastic doctor blade 6
09 to reduce the thickness of the developer layer (3
(0 μm to 300 μm) and is uniformly regulated, and a developer layer thinner than the gap between the photosensitive drum 603 and the developing sleeve 606 in the developing section is formed so as to be in non-contact. By adjusting the rotation speed of the sleeve 606, the surface speed of the sleeve is substantially equal to or close to the speed of the electrostatic image holding surface.

In the developing section, an AC bias or a pulse bias may be applied between the sleeve 606 and the photosensitive drum 603 by the bias means 612. This AC bias has f of 200 to 4,000 Hz and Vpp of 500.
It is preferable to be 3,000 V.

In the developing unit, the magnetic toner particles are transferred to the electrostatic image side by the electrostatic force on the surface of the photosensitive drum 603 holding the electrostatic image and the action of an AC bias or a pulse bias.

Further, another example of the image forming apparatus of the present invention will be described with reference to FIG.

In the image forming apparatus shown in FIG. 7, the layer thickness of the magnetic developer on the developing sleeve 606 is
16 is different from the image forming apparatus shown in FIG. 7, the members having the same reference numerals as those in FIG. 6 indicate the same members.

As the magnetic doctor blade 616, for example, an iron doctor blade is disposed close to the cylindrical surface (interval: 50 μm to 500 μm) and opposed to one magnetic pole position of the multi-pole permanent magnet, so that the developer layer The thickness is controlled to be thin (30 μm to 300 μm) and uniform, and a developer layer thinner than the gap between the photosensitive drum 603 and the developing sleeve 606 in the developing section is formed so as to be in non-contact.
By adjusting the rotation speed of the developing sleeve 606, the sleeve surface speed is substantially equal to or close to the speed of the electrostatic image holding surface. The opposed magnetic poles may be formed by using permanent magnets instead of iron as the magnetic doctor blade 616.

The electrophotographic apparatus is constructed by integrally combining a plurality of components such as an electrostatic latent image carrier such as the above-mentioned photosensitive drum, a developing device, and a cleaning unit as an apparatus unit. The unit may be configured to be detachable from the apparatus main body. For example, a unit is formed by integrally supporting at least one of the charging unit, the developing device, and the cleaning unit together with the photosensitive drum, and the unit is detachably attached to the apparatus main body. It may be configured to be detachable. At this time, the charging unit and / or
Alternatively, it may be configured with a developing device.

FIG. 8 shows an embodiment of the apparatus unit of the present invention. In this embodiment, an electrophotographic image forming apparatus including an image forming unit (a so-called cartridge) 618 in which a developing device 601, a photosensitive drum 603, a cleaner 614, and a primary charger 611 are integrated is exemplified.

In this apparatus, the image forming unit 6
When the magnetic developer 613 of the developing device 601 in the cartridge 18 runs out, the cartridge is replaced with a new cartridge.

The developing device 601 uses a one-component magnetic developer as the developer 613.
The distance between the photosensitive drum 603 and the developing sleeve 606 is very important so that a predetermined electric field is formed between the photosensitive drum 603 and the developing sleeve 606 so that the developing process is suitably performed. In this embodiment, the center is 300 μm and the error is ± 3.
It is adjusted to be 0 μm.

An apparatus unit 618 shown in FIG. 8 includes a developer container 602 for containing a magnetic developer 613 and a magnetic developer 613 in the developer container 602.
A developing sleeve 606 that carries and conveys the developer to the developing area facing the latent image carrier 603, and a magnetic developer that is carried by the developing sleeve 606 and conveyed to the developing area by regulating the thickness of the magnetic developer to a predetermined thickness. And an elastic blade 609 for forming a thin layer of developer thereon.

FIG. 9 shows a transfer roller 922 as a transfer means.
And an image forming apparatus having a bias applying unit 928 for applying a bias to the transfer roller 922.

The contact pressure between the transfer roller 922 and the photosensitive drum 603 is preferably 3 g / cm or more as a linear pressure. The linear pressure is calculated by the following formula.

(Linear pressure) [g / cm] = (total pressure applied to transfer material) [g] ÷ (length in contact) [cm] If the contact pressure is less than 3 g / cm, transfer is performed. This is not preferable because transfer failure due to material conveyance deviation and insufficient transfer current is likely to occur. Particularly preferably, it is 20 g / cm or more (more preferably 25 to 80 g / cm).

The transfer roller 922 has a core bar 923 and a conductive elastic layer 924. The conductive elastic layer 924 is a polyurethane resin or an ethylene-propylene-diene terpolymer in which a conductive material such as carbon is dispersed. (EPDM)
Made of an elastic material having a volume resistance of 10 ⁶ to 10 ¹⁰ Ω · cm. A bias is applied to the metal core 923 by a constant voltage power supply 928. The bias conditions were a current value of 0.1 to 50 μA and a voltage (absolute value) of 100 to 5000.
V (preferably 500 to 4000 V) is preferred.

The toner obtained by the production method of the present invention exhibits particularly good transfer characteristics when applied to an image forming apparatus having a contact transfer means as shown in FIG.

[0093]

The present invention will be described below in more detail with reference to examples. Parts or% described in Examples are parts by weight or% by weight.

Example 1 100 parts of powder of styrene-n-butyl acrylate copolymer (specific gravity: 1.05, weight average molecular weight: 350,000) (average particle size: about 250 μm) Magnetic iron oxide particles (specific gravity: about 5, average Particle size about 0.2μm)
60 parts ・ Ethylene-polypropylene copolymer (specific gravity: about 1, number average molecular weight: about 3000) 4 parts ・ Chromium complex of monoazo dye (specific gravity: about 2, average particle size: about 3)
μm) 3 parts The combination of the above materials is referred to as composition A.

On the other hand, melt kneading using the composition A
Magnetic toner 10 having a weight average diameter of 11 μm produced by a pulverization method
0 parts and 0.6 parts of hydrophobic silica fine powder treated with dimethyl silicone oil (BET specific surface area: 200 m ² / g, treated amount of silicone oil: 10 wt%) were mixed by a Henschel mixer for 3 minutes to obtain a hydrophobic powder. The magnetic toner to which silica fine powder was externally added was introduced into the image forming apparatus shown in FIG. 7, and an image forming test was performed on a large number of sheets.

The magnetic toner in which 1.2 parts of hydrophobic silica fine powder treated with silicone oil was externally added to 100 parts of the magnetic toner was collected in the cleaning unit 614 shown in FIG. The average particle size of the secondary particles of the hydrophobic silica fine powder on the collected toner particles was about 40 μm. In the transfer step, the amount of hydrophobic silica fine powder added to the magnetic toner in the developing device was different from the external addition amount because hydrophobic silica remained on the photoreceptor.

A magnetic toner 1 comprising 167 parts of the above composition A and hydrophobic silica fine powder on the surface of the collected toner particles.
5 parts and 60 parts of fine powder (weight average particle size: about 6 μm) classified in a classification step described below were dry-mixed by a Henschel mixer under the following conditions.

Volume of mixing tank 300 liter Weight of mixture 80 kg Number of rotation of stirring blade 300 rpm Rotation time of stirring blade 2 minutes

Adhesion of the toner raw materials in the Henschel mixer was hardly observed.

The above mixture was kneaded using a twin-screw extruder (kneading shaft length (L) / diameter (D) = 30) at a heating temperature of 110 ° C. and a shaft rotation speed of 180 rpm. Particle size of about 100 to about 1000 μm by mill
And then pulverized by an ACM pulverizer manufactured by Hosokawa Micron Co., Ltd. to a weight average particle size of about 50 μm. Next, in the classification-pulverization system shown in FIG. 5, the pulverized material is put into the quantitative feeder 2a and introduced into the first classifier 9 (air flow classifier DS-10VR manufactured by Nippon Pneumatic Industries, Ltd.) to be classified. The coarse powder thus obtained was finely pulverized by a pulverizer 8 (Jet Mill PJM-I-10 manufactured by Nippon Pneumatic Industrial Co., Ltd.), and after fine pulverization, was circulated to a first classifier 9. The fine powder classified by the first classifier 9 is charged into a fixed-quantity feeder 10, and a multi-segment classifier 1 utilizing the Coanda effect via a vibration feeder 3 (Elbow Jet EJ-45 manufactured by Nippon Steel Mining Co., Ltd.) (Type 3 machine) to classify into coarse powder, medium powder and fine powder. The classified coarse powder was introduced into the first classifier 9 via the quantitative feeder 2b, and the classified fine powder was supplied to the premix. The classified medium powder (magnetic toner) had a weight average diameter (D ₄ ) of 11.5 μm.

The obtained toner particles were cut with a microtome (Ultracut N, Reinhardt Co.) and observed with a transmission electron microscope (Hitachi H-800). Was confirmed.

100 parts of the obtained magnetic toner and 0.6 part of hydrophobic silica fine powder treated with silicone oil were put into a Henschel mixer (30 kg in a 150-liter mixing tank, and the number of revolutions of stirring blades was 1500 rpm) for 3 minutes. By mixing, a magnetic toner having hydrophobic silica fine powder on the surface of the toner particles was prepared.

The magnetic toner is supplied to an apparatus unit (toner cartridge) of a commercially available laser beam printer LBP-8II (manufactured by Canon Inc.) shown in FIG. An electrostatic latent image is formed on an OPC photosensitive drum, a magnetic toner layer on a developing sleeve (including a magnet) is set in a non-contact manner with the photosensitive drum, a gap (300 μm) is set, and an AC bias (f = 1,80) is applied.
While applying 0 Hz, Vpp = 1,600 V) and a DC bias (V _DC = -500 V) to the developing sleeve, _VL is set to -170 V, the electrostatic image is developed by reversal development, and the magnetic toner image is converted to the OPC photoconductor. Formed on top. The formed magnetic toner image is transferred to plain paper at a positive transfer potential, and the plain paper having the magnetic toner image is fixed to the magnetic toner image through a heating / pressing roller fixing device. Environment (23.5 ° C, 60% R
H) An image output test was performed up to 6000 sheets. Image density measured by a Macbeth reflection densitometer, fog calculated from a comparison between the whiteness of the transfer paper measured by a reflectometer (manufactured by Tokyo Denshoku Co., Ltd.) and the whiteness of the transfer paper after printing solid white, and Table 1 shows the results of the dot image reproducibility obtained by performing the pattern image test shown in FIG.

Similarly, under a high temperature and high humidity environment (32.5
℃, 85% RH) and low temperature and low humidity environment (10 ℃, 15%
RH). Table 1 shows the results.

Example 2 100 parts of styrene-2-ethylhexyl acrylate copolymer 100 parts of magnetic iron oxide particles 2 parts of low molecular weight polypropylene 2 parts of chromium complex of dialkylsalicylic acid type The combination of the above materials is referred to as composition B.

In the same manner as in Example 1, 100 parts of a magnetic toner (weight average particle size: 6.5 μm) formed from the composition B was treated with silicone oil to prepare a hydrophobic silica fine powder.
20 parts of a magnetic toner (average particle diameter of secondary particles of hydrophobic silica fine powder on toner particles: about 50 mμ) externally added with 2 parts by a Henschel mixer in the same manner as in Example 1 and a composition classified in a classification step Fine powder of B (weight average diameter about 4.2 μm)
100 parts together with the composition B (204 parts) were placed in a Henschel mixer, and premixed as in Example 1. At this time, adhesion of the toner raw materials to the Henschel mixer was hardly observed. Further, a magnetic toner having a weight average diameter (D ₄ ) of 6.5 μm was obtained in the same manner as in Example 1 except that L / D of the uniaxial extruder was changed to 23.

The obtained toner particles were observed with a microtome transmission electron microscope in the same manner as in Example 1.
It was confirmed that each component was dispersed very well.

100 parts of this magnetic toner and 0.5 parts of hydrophobic silica hydrophobized with silicone oil were mixed with a Henschel mixer to obtain a magnetic toner having fine hydrophobic silica powder on the surface of toner particles.

As shown in FIG. 6, the device unit (toner cartridge) of the laser beam printer LBP-8II (manufactured by Canon Inc.) was modified as shown in FIG.
An urethane rubber elastic blade was supplied to an apparatus unit (cartridge) in contact with an aluminum developing sleeve at a contact pressure of 30 g / cm, and an image-drawing test was performed in the same manner as in Example 1. Table 1 shows the results.

Example 3 Styrene-n-butyl acrylate copolymer 100
Part-magnetic iron oxide particles 80 parts-ethylene-propylene copolymer 4 parts-monoazo dye-based chromium complex 3 parts The combination of the above materials is referred to as composition C.

100 parts of a magnetic toner prepared in the same manner as in Example 1 from Composition C, and hexamethyldisilazane (1
0 wt%) and then silicone oil (10 wt%)
%) And a magnetic toner obtained by mixing with 0.5 part of hydrophobic silica using a Henschel mixer in the same manner as in Example 1 and introducing the magnetic toner into an image forming apparatus shown in FIG. Was done.

In cleaning section 614 shown in FIG. 7, hydrophobic silica fine powder treated with dimethyldisilazane and silicone oil was added to 100 parts of magnetic toner.
Six parts of the magnetic toner externally added were collected. The average particle size of the secondary particles of the hydrophobic silica fine powder on the collected toner particles was about 45 μm.

15 parts of the recovered toner, 3 parts of a molded product (average diameter of about 0.5 mm) of fine powder (weight average particle size of about 5.8 μm) classified in the classification step, and Composition C (187 parts) The mixture was placed in a Henschel mixer and premixed in the same manner as in Example 1. At this time, adhesion of the toner raw materials to the Henschel mixer was hardly observed. Further, a magnetic toner having a weight average diameter (D ₄ ) of 9.2 μm was obtained in the same manner as in Example 1 except that L / D of the biaxial extruder was changed to 40.

When the obtained magnetic toner particles were observed with a microtome and a transmission electron microscope in the same manner as in Example 1, it was confirmed that each component was dispersed very well.

100 parts of this toner and 0.5 parts of hydrophobic silica treated with hexamethyldisilazane and then treated with silicone oil were mixed in a Henschel mixer to obtain a magnetic toner having hydrophobic silica fine powder on the surface of toner particles. .
An image-drawing test was performed on the magnetic toner in the same manner as in Example 1. Table 1 shows the results.

Example 4 100 parts of styrene-2-ethylhexyl acrylate copolymer 60 parts of magnetic iron oxide particles 4 parts of low molecular weight polypropylene 3 parts of monoazo dye-based chromium complex A combination of the above materials is referred to as composition D.

In the same manner as in Example 1, 0.6 part of hydrophobic silica fine powder treated with dimethyldichlorosilane was added to 100 parts of a magnetic toner (weight average particle diameter: 11.5 μm) formed from the composition D. Molded product of 120 parts of toner (an average particle diameter of secondary particles of hydrophobic silica fine particles on toner particles is about 30 μm) externally added by a Henschel mixer and fine powder of composition D classified in the classification step in the same manner as in Example 1. (Diameter average about 4
mm) 10 parts together with the composition D were placed in a Henschel mixer and premixed as in Example 1. At this time, adhesion of the toner raw materials to the Henschel mixer was hardly observed. Further, a magnetic toner having a weight average diameter (D ₄ ) of 11.5 μm was obtained in the same manner as in Example 1 except that L / D of the biaxial extruder was set to 16.

When the obtained magnetic toner particles were observed using a microtome transmission electron microscope in the same manner as in Example 1, it was confirmed that each component was dispersed very well.

100 parts of this magnetic toner and 0.6 parts of silica fine powder hydrophobized with silicone oil were mixed with a Henschel mixer to obtain a magnetic toner having hydrophobic silica fine powder on the surface of toner particles. An image-drawing test was performed on this magnetic toner in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 1 Premixing was carried out using only composition A. At this time, magnetic iron oxide of the toner raw materials was slightly adhered to the blades of the Henschel mixer. L / D of twin-screw extruder
A magnetic toner having a weight average diameter (D ₄ ) of 11.5 μm was obtained in the same manner as in Example 1 except that the value was set to 14.

The obtained toner particles were observed using a microtome transmission electron microscope in the same manner as in Example 1.
Small clumps of magnetic iron oxide were slightly visible.

100 parts of this magnetic toner and 0.6 parts of hydrophobic silica fine powder treated with dimethyldichlorosilane were mixed with a Henschel mixer to obtain a magnetic toner having hydrophobic silica fine powder on the surface of toner particles. An image-drawing test was performed on the magnetic toner in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 2 Composition B and Fine Powder 100 of Composition B Classified in Classification Step
Parts and 0.2 parts of the hydrophobic silica fine powder itself treated with silicone oil were placed in a Henschel mixer, and premixed in the same manner as in Example 1. At this time, adhesion of the toner raw material in the Henschel mixer was observed.
Then, in the same manner as in Example 1, the weight average diameter (D ₄ ) 6.
A magnetic toner of 4 μm was obtained.

When the obtained magnetic toner particles were observed using a microtome transmission electron microscope in the same manner as in Example 1, large clusters of magnetic iron oxide were found in the toner particles.

100 parts of this magnetic toner and 0.5 parts of hydrophobic silica fine powder subjected to hydrophobic treatment with silicone oil were mixed with a Henschel mixer to obtain a magnetic toner having hydrophobic silica fine powder on the surface of toner particles. This magnetic toner was supplied to an apparatus unit (cartridge) of a laser beam printer LBP8II, and an image output test was performed in the same manner as in Example 1. Table 1 shows the results.

[0126]

[Table 1]

Experimental Example The magnetic toner prepared in Examples 1 to 4 and the magnetic toner prepared in Comparative Examples 1 and 3 were introduced into an image forming apparatus (transfer by a transfer roller) shown in FIG. A take-out test was performed. Table 2 shows the results.

[0128]

[Table 2]

Evaluation Criteria An alphabet having a length of 3 mm and a width of 2 mm was printed on A4 size paper, and the evaluation was made based on the number of alphabets having a poor degree of hollowness per 100 alphabets.

◎: 0 to 5 ○: 6 to 10…: 11 or more

Example 5 Styrene-n-butyl acrylate copolymer powder (specific gravity: 1.05; weight average molecular weight: 350,000; average particle size: about 2
50 μm) 100 parts ・ Magnetic iron oxide particles (specific gravity: about 5, average particle size: about 0.2 μm)
100 parts ・ Ethylene-propylene copolymer (specific gravity: about 1, number average molecular weight: about 3000) 3 parts ・ Chromium complex of monoazo dye (specific gravity: about 2, average particle size: about 3)
μm) 2 parts The combination of the above materials is referred to as composition E.

100 parts of magnetic toner prepared from composition E in the same manner as in Example 1 and 1.2 parts of hydrophobic silica fine powder treated with silicone oil were mixed with a Henschel mixer in the same manner as in Example 1. FIG. 7 shows the magnetic toner
And an image forming test was performed on a large number of sheets.

In the cleaning unit 614 shown in FIG. 7, magnetic toner in which 3 parts of hydrophobic silica fine powder treated with silicone oil were externally added to 100 parts of magnetic toner was collected. The average particle size of the secondary particles of the hydrophobic silica fine powder on the collected toner particles was about 40 mμ.

5 parts of the recovered magnetic toner and composition E
(205 parts) in a Henschel mixer
The pre-mixing was performed in the same manner as described above.

The toner raw materials hardly adhered in the Henschel mixer.

The mixture was melt-kneaded using a twin-screw extruder (kneading shaft length (L) / diameter (D) = 3) at a heating temperature of 110 ° C. and a shaft rotation speed of 200 rpm. Similarly, pulverization and classification were performed to obtain a magnetic toner having a weight average particle size (D ₄ ) of 7.0 μm.

The obtained toner particles were cut with a microtome (Ultracut N, Reinhardt Co.), and the cut surface was observed using a transmission electron microscope (Hitachi H-800). It was confirmed that. 100 parts of this magnetic toner and 1.2 parts of hydrophobic silica fine powder treated with silicone oil were mixed with a Henschel mixer to prepare a magnetic toner having hydrophobic silica fine powder on the surface of toner particles.

A commercially available laser beam printer LBP-
The apparatus unit (toner cartridge) of 8II (manufactured by Canon Inc.) was modified as shown in FIG. 6, and an urethane rubber elastic blade was brought into contact with an aluminum developing sleeve at a contact pressure of 30 g / cm.

Using the above magnetic toner, primary charging was -7
At 0 V, an electrostatic latent image for reversal development is formed on the OPC photosensitive drum 3, and the magnetic toner layer on the developing sleeve 6 (including the magnet) is brought into contact with the photosensitive drum 3 without contact with the gap (300 μm).
m) and set the AC bias (f = 1,800 Hz, V
pp = 1,600 V) and DC bias (V _DC = −5)
While applying a 00V) and the developing sleeve, the V _L -1
The electrostatic charge image was developed by reversal development at 70 V to form a magnetic toner image on the OPC photoconductor. The formed magnetic toner image was transferred to plain paper at a positive transfer potential, and the plain paper having the magnetic toner image was fixed on the plain paper through a heat and pressure roller fixing device.

An image output test was performed on up to 6000 sheets in a normal temperature and normal humidity environment (23.5 ° C., 60% RH) while replenishing the magnetic toner. Image density measured by a Macbeth reflection densitometer, fog calculated from a comparison between the whiteness of the transfer paper measured by a reflectometer (manufactured by Tokyo Denshoku Co., Ltd.) and the whiteness of the transfer paper after printing solid white, and Table 3 shows the results of the dot image reproducibility of the image shown in FIG.

Similarly, in a high temperature and high humidity environment (32.5
℃, 85% RH) and low temperature and low humidity environment (10 ℃, 15%
RH). Table 3 shows the results.

Example 6 Styrene-2-ethylhexyl acrylate copolymer 100 parts Magnetic iron oxide particles 60 parts Low molecular weight polypropylene 3 parts Dialkyl salicylic acid chromium complex 3 parts A combination of the above materials is referred to as composition F. .

In the same manner as in Example 1, 100 parts of a magnetic toner (weight average particle diameter: 12 μm) formed from the composition F was added to
Hydrophobic silica fine powder treated with silicone oil 0.5
85 parts of a magnetic toner (average particle diameter of secondary particles of hydrophobic silica fine powder on toner particles of about 50 μm) externally added by a Henschel mixer in the same manner as in Example 1, and composition F (1
(66 parts) with a Henschel mixer in the same manner as in Example 1.

At this time, adhesion of the toner raw material to the Henschel mixer was hardly observed. Further, a magnetic toner having a weight average diameter (D ₄ ) of 12.0 μm was obtained in the same manner as in Example 1 except that the uniaxial extruder L / D was set to 22.

The obtained magnetic toner particles were observed using a microtome transmission electron microscope in the same manner as in Example 1. As a result, it was confirmed that each component was dispersed very well.

100 parts of this magnetic toner and 0.5 parts of hydrophobic silica fine powder hydrophobized with silicone oil were mixed with a Henschel mixer to obtain a magnetic toner having hydrophobic silica fine powder on the surface of toner particles. This magnetic toner was supplied to an apparatus unit (cartridge) of a laser beam printer LBP-8II, and an image output test was performed in the same manner as in Example 1. Table 3 shows the results.

Example 7 Styrene-n-butyl acrylate copolymer 100
Part 80 parts of magnetic iron oxide particles 4 parts of ethylene-propylene copolymer 2 parts of monoazo dye-based chromium complex The combination of the above materials is referred to as composition G.

In the same manner as in Example 1, 100 parts of a magnetic toner prepared from the composition G was treated with hexamethyldisilazane (10 wt%), and then treated with a silicone oil (10 wt%).
t%) and mixed with 0.9 parts of hydrophobic silica using a Henschel mixer in the same manner as in Example 1 and introduced into an image forming apparatus shown in FIG. The test was performed.

In cleaning section 614 shown in FIG. 7, hydrophobic silica fine powder treated with dimethyldisilazane and silicone oil with respect to 100 parts of magnetic toner.
Two parts of the magnetic toner externally added were recovered. The average particle size of the secondary particles of the hydrophobic silica fine powder on the collected toner particles was about 45 μm.

15 parts of the recovered toner and the composition G (186)
) Was placed in a Henschel mixer and premixed as in Example 1.

Further, the twin-screw extruder L / D = 40
Except that the weight average diameter (D
₄ ) A 9.2 μm magnetic toner was obtained.

When the obtained magnetic toner particles were observed with a microtome and a transmission electron microscope in the same manner as in Example 1, it was confirmed that each component was dispersed very well.

100 parts of this magnetic toner and 0.5 part of hydrophobic silica fine powder treated with hexamethyldisilazane and then treated with silicone oil were mixed in a Henschel mixer to form a magnetic toner having hydrophobic silica fine powder on the surface of toner particles. I got Using this magnetic toner, an image output test was performed in the same manner as in Example 1. Table 3 shows the results.

Example 8 Styrene-n-butyl acrylate copolymer 100
Part 65 parts of magnetic iron oxide particles 4 parts of low molecular weight polypropylene 3 parts of monoazo dye-based chromium complex The combination of the above materials is referred to as composition H.

In the same manner as in Example 1, 100 parts of a magnetic toner (weight average particle diameter: 11.5 μm) formed from the composition H was treated with 0.6 part of hydrophobic silica fine powder treated with dimethyldichlorosilane. In a Henschel mixer, 100 parts of a magnetic toner (average particle diameter of secondary particles of hydrophobic silica fine powder on toner particles: about 30 mμ) externally added by a Henschel mixer and a composition H (172 parts) in the same manner as in 1 were used. And then premixed as in Example 1.

When the obtained magnetic toner particles were observed using a microtome and a transmission electron microscope in the same manner as in Example 1, it was confirmed that each component was dispersed well.

100 parts of this magnetic toner and 0.6 parts of hydrophobic silica fine powder hydrophobized with silicone oil were mixed with a Henschel mixer to obtain a magnetic toner having hydrophobic silica fine powder on the surface of magnetic toner particles. . An image-drawing test was performed on this magnetic toner in the same manner as in Example 1. Table 3 shows the results.

[0158]

[Table 3]

[0159]

According to the present invention as described above,
By adding resin particles carrying or containing an inorganic fine powder at the time of pre-mixing, it is possible to produce a toner having stable image density, no fog, and excellent dot reproducibility.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating a specific example of a toner manufacturing method according to the present invention.

FIG. 2 is a flowchart illustrating another specific example of the toner manufacturing method of the present invention.

FIG. 3 is a schematic explanatory view of a Henschel mixer showing a specific example of a dry mixer used for premixing.

FIG. 4 is an explanatory view of a screw of an extruder.

FIG. 5 is an explanatory view showing a specific example of a classifying step and a fine pulverizing step of the coarsely pulverized product after cooling the melt-kneaded product and coarsely pulverizing the cooled product.

FIG. 6 is a schematic explanatory view showing a specific example of an image forming apparatus using a toner.

FIG. 7 is a schematic explanatory view showing another specific example of an image forming apparatus using a toner.

FIG. 8 is an explanatory diagram of an apparatus unit forming a part of the image forming apparatus shown in FIG.

FIG. 9 is a schematic explanatory view showing a specific example of an image forming apparatus having a transfer roller.

FIG. 10 is an explanatory diagram of a checker pattern for evaluating development characteristics of a toner.

FIG. 11 is an image sample for evaluating omission during transfer.

FIG. 12 is an explanatory diagram of an image sample in which a dropout during transfer has occurred.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Three-class classifier 2a, 2b Quantitative feeder 3 Vibration feeder 4, 5, 6, 7 Cyclone 8 Crusher 9 1st classifier 10 Quantitative feeder 11, 12, 13 Discharge conduit 30 Bag filter 922 Transfer roller 923 Core metal 924 conductive elastic layer 928 bias applying means

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-323668 (JP, A) JP-A-5-34976 (JP, A) JP-A 4-218065 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) G03G 9/08-9/087

Claims (34)

(57) [Claims] (A) carrying or containing an inorganic fine powder
The resin particles, (B) the binder resin particles and (C) the colorant are pre-mixed to prepare a mixture, and the mixture is melt-kneaded to obtain a kneaded product, and the kneaded product is cooled. A toner for developing an electrostatic charge image, comprising: obtaining a colored resin solid; crushing the colored resin solid to obtain a crushed product; and containing toner particles obtained by classifying the crushed product. 2. The electrostatic image developing toner according to claim 1, wherein the inorganic fine powder is a silica fine powder. 3. The electrostatic image developing toner according to claim 2, wherein the inorganic fine powder is a hydrophobic silica fine powder. 4. The electrostatic image developing toner according to claim 3, wherein the inorganic fine powder is a hydrophobic silica fine powder treated with silicone oil. 5. The electrostatic image developing toner according to claim 1, wherein the toner and the resin particles to be added have the same composition. 6. The electrostatic image developing toner according to claim 1, wherein the toner and the resin particles to be added are magnetic toners. 7. The electrostatic image developing toner according to claim 1, wherein the inorganic fine powder is a titanium oxide fine powder. 8. The electrostatic image developing toner according to claim 7, wherein the inorganic fine powder is a hydrophobic titanium oxide fine powder. 9. The toner for developing an electrostatic image according to claim 8, wherein the inorganic fine powder is a hydrophobic titanium oxide fine powder treated with silicone oil. 10. The electrostatic image developing toner according to claim 1, wherein in the premixing step, fine powder classified in the classification step is further added. 11. The method according to claim 10, wherein the total amount of the resin particles carrying or containing the inorganic fine powder and the fine powder is 2 to 60% by weight based on all the materials used in the premixing step. An electrostatic image developing toner. 12. (A) carrying or containing an inorganic fine powder
The resin particles, (B) the binder resin particles and (C) the colorant are pre-mixed to prepare a mixture, and the mixture is melt-kneaded to obtain a kneaded product, and the kneaded product is cooled. A method for producing a toner for developing an electrostatic image, comprising: obtaining a colored resin solid; pulverizing the colored resin solid to obtain a pulverized product; and classifying the pulverized product to generate toner particles. 13. The method according to claim 12, wherein the inorganic fine powder is externally added to the surface of the resin particles in advance. 14. The method for producing a toner for developing electrostatic images according to claim 12, wherein the inorganic fine powder is a silica fine powder. 15. The method for producing a toner for developing electrostatic images according to claim 14, wherein the inorganic fine powder is a hydrophobic silica fine powder. 16. The method according to claim 15, wherein the inorganic fine powder is a hydrophobic silica fine powder treated with silicone oil. 17. The method for producing a toner for developing an electrostatic image according to claim 12, wherein the inorganic fine powder is a titanium oxide fine powder. 18. The method for producing a toner for developing an electrostatic image according to claim 17, wherein the inorganic fine powder is a hydrophobic titanium oxide fine powder. 19. The fine inorganic powder is a hydrophobic titanium oxide fine powder treated with silicone oil.
3. The method for producing a toner for developing an electrostatic image according to item 1. 20. The electrostatic image development according to claim 12, wherein the inorganic fine powder is preliminarily supported or contained in resin particles such that the average particle size of the secondary particles is 100 mμ or less. Of manufacturing toner for toner. 21. The electrostatic image development according to claim 12, wherein the pulverized material is at least classified into a coarse powder, a medium powder, and a fine powder, and the classified fine powder is supplied to a premixing step. Of manufacturing toner for toner. 22. The method for producing a toner for developing an electrostatic image according to claim 12, wherein the mixture contains 1 to 50% by weight of resin particles carrying or containing an inorganic fine powder. Method. 23. The electrostatic charge according to claim 12, wherein the total of the fine powder and the resin particles carrying or containing the inorganic fine powder is 2 to 60% by weight in the mixture. A method for producing an image developing toner. 24. The electrostatic charge according to claim 12, wherein the fine powder and the resin particles carrying or containing the inorganic fine powder are blended in a weight ratio of 1:20 to 20: 1. A method for producing an image developing toner. 25. The inorganic fine powder is hydrophobic silica fine powder treated with silicone oil, said hydrophobic silica fine powder being dry-mixed with resin particles in advance, and the surface of the resin particles after dry-mixing. The secondary particles of the hydrophobic silica fine powder supported on the top have an average particle size of 100 μm or less, and the resin particles supporting the inorganic fine particles, the binder resin particles, and the colorant are added in advance. Claims 12 to 16 which are mixed
25. The method for producing a toner for developing an electrostatic image according to any one of 20 to 24 . 26. The hydrophobic silica fine powder and the resin particles are dry-mixed to make the average particle size of secondary particles of the hydrophobic silica fine powder present on the surface of the resin particles 100 mμ or less,
Next, a mixture of the hydrophobic silica fine powder and the resin particles is molded to obtain resin particles containing the hydrophobic silica fine powder, and then pre-mixed with the binder resin particles and the colorant. 25. The method for producing an electrostatic image developing toner according to any one of the above items 25. 27. The binder resin particles have a number average particle size of 10 to 10.
The method for producing a toner for developing electrostatic images according to any one of claims 12 to 26, wherein the toner has a thickness of 1000 µm. 28. The method according to claim 12, wherein the colorant has a number average particle size of 3 μm or less. 29. The mixture contains 100 parts by weight of binder resin particles, 2 to 150 parts by weight of a coloring agent, 0.1 to 5 parts by weight of inorganic fine powder, and 1 to 50 parts by weight of resin particles. 29. The method for producing a toner for developing an electrostatic image according to any one of the above items. 30. The method according to claim 12, wherein the inorganic fine powder is a silica fine powder, and the resin particles are toner particles. 31. The method of claim 16, wherein the hydrophobic silica fine powder is treated with 1 to 35 parts by weight of silicone oil per 100 parts by weight. 32. The method of claim 19, wherein the fine titanium oxide powder is treated with 1 to 35 parts by weight of silicone oil per 100 parts by weight. 33. Premixing a resin particle carrying or containing an inorganic fine powder treated with a binder resin particle, a colorant and silicone oil while receiving a shearing force by a mixing means having a plurality of stirring blades. The method for producing a toner for developing an electrostatic image according to any one of claims 12 to 32. 34. The toner according to claim 12, wherein the mixture is melt-kneaded in an extruder having a ratio (L / D) of the length (L) to the diameter (D) of 17 to 50 of the kneading shaft. Manufacturing method.