JP2649363B2 - Development method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention was formed on the surface of an organic photoconductor made of an organic photoconductive semiconductor in electrophotography, electrostatic recording, electrostatic printing, and the like. The present invention relates to a dry developing method for developing an electrostatic latent image.

BACKGROUND OF THE INVENTION In general, in electrophotography, a photoreceptor having a photosensitive layer made of a photoconductive material is provided with a uniform electrostatic charge, and then subjected to image exposure to thereby form an electrostatic latent image on the surface of the photoreceptor. Is formed, and the electrostatic latent image is developed with a developer to form a toner image. The obtained toner image is transferred to a transfer material such as paper, and then fixed by heating or pressurizing to become a final copy image.

As a photoreceptor used for electrophotography, an inorganic photoreceptor such as a selenium photoreceptor, a zinc oxide photoreceptor, and a cadmium sulfide photoreceptor, and an organic photoreceptor made of an organic semiconductor are known. There is a problem that heat resistance is poor such as easy crystallization in a high temperature environment, sensitivity characteristics are deteriorated, and an unclear image is produced. In addition, in the case of a zinc oxide photoreceptor or a cadmium sulfide photoreceptor, the photosensitivity is easily deteriorated by image exposure at an early stage, fog is generated, resulting in an unclear image and poor durability, and the toxicity to the human body is accused.

On the other hand, organic photoconductors do not have the above-mentioned disadvantages, have good film sensitivity, are low in construction cost, and have advantages such as high sensitivity, durability, heat resistance, and no toxicity to the human body. Body.

As a developer used for developing an electrostatic latent image formed on the surface of a photoreceptor, a one-component developer and a two-component developer are generally known. The former one-component developer is composed of a magnetic toner in which a magnetic material or the like is dispersed and contained in a binder resin, and the latter two-component developer is composed of a toner and a carrier composed of magnetic particles.

As a method of developing using such a developer, a magnetic brush method, a cascade method, a fur brush method, a powder cloud method, a jumping method, a magnedry method, and the like are generally used.

In a developing method using a two-component developer composed of a toner and a carrier, usually, only the toner is consumed, so that the toner concentration in the developer tends to change. Therefore, a control mechanism for appropriately replenishing the toner is required. In addition, there are various inconveniences in terms of developer management, such as the fact that toner and carrier are liable to be scattered, and thus need to be prevented.

In order to avoid such a problem, a one-component developer that does not require a carrier and includes only toner has been proposed. In a contact developing method such as a magnetic brush method or a fur brush method using a one-component developer, the toner easily adheres even to a non-image portion, so-called fogging easily occurs, and the photosensitive member is rubbed by the developer. Therefore, particularly in the case of the organic photoreceptor, the cleaning is likely to occur due to scratches or the like. As a developing method for removing such fogging, a powder cloud method and a jumping method in which toner is caused to fly and developed while keeping the surface of the photosensitive member and the developer in non-contact have been proposed.

However, if the powder cloud method or the jumping method is used, fogging and the like can be somewhat improved by using the conventional toner, but it has the following disadvantages.

Due to the gap between the developer layer and the surface of the photoreceptor, the developing electric field is small, which has the disadvantage that the developability, that is, the amount of toner adhered to the latent image is reduced, and the image density is low.

In the case of a one-component magnetic toner containing magnetic particles, a slight frictional charge caused by the toner particles, a toner and a regulating blade for regulating the height of the surface of the developer carrier or the height of the developer layer disposed in the developing device, etc. Friction charge is imparted to the toner by friction charge, but the magnetic particles in the magnetic toner are easily charged negatively, the binder resin portion is easily charged positively, and both positive and negative charges are present on the toner particle surface. That means
As a result, when the toner is used many times, the ratio of the toner of the opposite polarity and the toner of the weak charge increases, and the toner tends to adhere to the non-image portion on the surface of the photoconductor.

The presence of positive and negative charges on the surface of the toner particles causes electrostatic aggregation of the toner particles, which significantly reduces the fluidity of the developer, resulting in poor transportability of the developer to the developing area. As a result, the image density is lowered and a non-uniform developer layer is formed.

In addition, because the fluidity of the developer is poor, an oscillating electric field is applied to give the toner particles easy movement, so that the toner particles fly to the surface of the photoconductor,
There is a drawback that sufficient transfer is not achieved even if an attempt is made to transfer, and the developability is low.

Since the magnetic material in the magnetic toner particles is extremely hard, when cleaning the toner remaining on the surface of the soft organic photoreceptor formed by the resin after transfer with the cleaning blade, the toner particles cause the surface of the photoreceptor and the cleaning blade to be cleaned. The toner is easily damaged, so that the toner is embedded in the damaged portion to cause filming or to easily pass through the cleaning blade, thereby causing a cleaning defect such as black spots or streaks on an image. .

In order to solve such a problem, Japanese Patent Publication No. 53-22447
No., JP-A-53-66235, JP-A-56-123550, JP-A-59-34539
No. 59-201063 and the like, attempts have been made to add aminosilane coupling agents, coupling with aminosilane coupling agents for hydrophobicity, and addition of silica fine particles treated with silicone oil having an amine in the side chain. However, sufficient performance has not been satisfied. In particular, under high humid environmental conditions, which are susceptible to humidity, if the toner is repeatedly used a number of times, the triboelectric charging property becomes non-uniform, the non-uniformity, and the fluidity become remarkable. Silica fine particles accumulate, resulting in poor cleaning.

[Objects of the Invention] (1) The present invention provides fogging in an image forming method in which an electrostatic latent image formed on an organic photoreceptor is applied with an oscillating electric field to cause toner to fly even under high humidity environmental conditions. (2) To provide an image forming method capable of obtaining an image having good developability and a high image density without using a magnetic toner in the image forming method even when the seed is high and the toner is used many times. To provide an image forming method with high stability and high durability without fogging,
(3) To provide an image forming method which has good fluidity and does not cause image unevenness even when a magnetic toner is used in the image forming method even in a high humidity. (4) A magnetic toner is applied to an organic photoreceptor even in a high humidity. An object of the present invention is to provide an image forming method in which a cleaning blade can be satisfactorily cleaned for a long period even when the method is applied, and a clear image can be obtained.

[Means for Achieving the Object] An object of the present invention is to generate an electric field in a development area, develop an electrostatic latent image formed on the surface of a photoreceptor with a developer, and perform a cleaning process using a cleaning member. The electric field is an oscillating electric field, the photoconductor is an organic photoconductor, the electrostatic latent image is a negative electrostatic latent image, and the cleaning member is a cleaning blade made of urethane rubber. Wherein inorganic fine particles obtained by subjecting a magnetic toner particle containing a magnetic material particle as a developer to a surface treatment of a polysiloxane containing a structural unit represented by the following formula (A) having an ammonium salt as a functional group are externally treated. This has been attained by an image forming method characterized in that it is a developer obtained by mixing.

Formula (A) (Where R ₁ is a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, or R ₂ represents a bonding group or a mere bond, R ₃ , R ₄ and R ₅ each represent a hydrogen atom, an alkyl group or an aryl group, and X represents a halogen atom. Each group represented by R _{1 to} R ₅ includes those having a substituent.

[Operation and Effect of the Present Invention] In the present invention, specific inorganic fine particles are externally added to and mixed with magnetic toner particles, so that the specific inorganic fine particles adhere to the surface of the magnetic toner particles and exist. On the surface of the magnetic toner, the specific inorganic fine particles adhere to portions of the magnetic particles that are partially exposed. This is because the magnetic particles have a negative charge property, and thus the specific positively chargeable inorganic fine particles of the present invention are easily attached by electrostatic force. As a result, the negatively chargeable sites on the surface of the toner particles have a high positive chargeability due to the adhesion of the inorganic fine particles, and thus the toner has a uniform and high positive chargeability without reverse polarity sites. As a result, even if copying is repeated many times, since there is no toner of the opposite polarity, the toner does not adhere to the non-image portion and fogging does not occur, and development with good durability can be achieved. In addition, since only a single-polarity toner is used, the developing efficiency is improved, and even in a developing method in which a gap exists between the developer layer and the photoreceptor surface, good developability is exhibited and high image density is achieved. Is obtained. Also, since neither positive nor negative polarities are present on the surface of the toner particles, electrostatic aggregation of the toner particles is prevented, whereby the fluidity is good and the toner particles are easy to move when an oscillating electric field is applied. In addition, the toner easily transfers to the surface of the photoreceptor, thereby improving the developing property. Furthermore, since the developer can be transported to the developing area with good transportability and a uniform developer layer can be formed, a reduction in image density and image unevenness can be prevented.

The specific inorganic fine particles are obtained by treating the surface of the inorganic fine particles with a polysiloxane having an ammonium salt as a functional group. The ammonium salt functional groups are more polarizable by ionization than amino groups, so that the positive charge density is higher. , It is possible to impart a high positive charge even under a high humidity environmental condition. In addition, by using an ammonium salt structure, the adhesiveness is small, and the adhesiveness to the photoreceptor surface and the triboelectric charging member can be reduced,
Filming and contamination can be prevented. Also, compared to the coupling agent which is a monomer, since it is a polymer, it can uniformly cover the surface of the inorganic fine particles, so that hydrophilic sites and negatively-charged sites (for example, -OH groups) present on the surface of the inorganic fine particles are present on the surface. It does not remain, thereby providing a stable and high positive charging property even under high humidity conditions.

In addition, inorganic fine particles treated with a polysiloxane having an ammonium salt as a functional group, which has low adhesion and is relatively soft even under high humidity conditions, are relatively easy to film on organic photoreceptor surfaces and cleaning blades. However, even if they adhere slightly, they can be easily cleaned by the cleaning blade. Further, the toner particles obtained by adhering such specific inorganic fine particles to the toner surface come into contact with the surface of the organic photoreceptor through the specific inorganic fine particles having low adhesiveness, so that the toner is transferred to the surface of the organic photoreceptor. Filming can be prevented, and the adhesion of toner particles to the surface of the photoreceptor can be reduced, so that the cleaning performance of the residual toner on the surface of the photoreceptor by the cleaning blade is improved as compared with the conventional toner. . Further, the specific inorganic fine particles adhered to the surface of the toner particles can prevent the toner particles from contaminating and contaminating the surface of the photoreceptor, thereby providing a developing method with good durability.

Further, according to the developer of the present invention, to develop a negative electrostatic latent image formed on the surface of the organic photoreceptor, without impairing the advantage of the organic photoreceptor that the production cost is low and there is no toxicity, The negative electrostatic latent image formed on the organic photoreceptor can be favorably developed without fogging or poor cleaning, and particularly, since the fluidity of the developer is good, It is possible to form a uniform and uniform developer layer and easily transfer and adhere to the photoreceptor surface by applying an oscillating electric field, thereby causing image unevenness,
Good development can be achieved without lowering of image density and occurrence of fog. Further, since the development is performed without rubbing the surface of the photoreceptor by the developer layer having a uniform chargeability, an image having excellent resolution can be provided.

[Specific Configuration of the Invention] As the polysiloxane having an ammonium salt as a functional group used for the specific inorganic fine particles of the present invention, a dimethylpolysiloxane having an ammonium base having a high positive chargeability and hardly causing cleaning failure is used. Preferably, there is. The dimethylpolysiloxane having an ammonium base is generally a dimethylsiloxane containing a structural unit represented by the following formula (A), and is represented by, for example, a structural formula represented by the following formula (B).

(A) formula (Where R ₁ is a hydrogen atom, an alkyl group, an aryl group,
An alkoxy group, or Wherein R ₂ is a bonding group (for example, an alkylene group, an arylene group, an aralkylene group, -NH-, -NHCO-, or a group obtained by combining these groups arbitrarily);
Or a mere bond, R ₃ , R ₄ and R ₅ each represent a hydrogen atom, an alkyl group or an aryl group, and X represents a halogen atom. Each group represented by R _{1 to} R ₅ includes those having a substituent. Equation (B) (Here, R ₆ and R ₇ each represent a hydrogen atom, an alkyl group, an aryl group, or an alkoxy group, and these groups include those having a substituent. R _{1 to} R ₅ and X are the same as those in the above (A). .m synonymous with R ₁ to R _5, X in the formula, n represents an integer of 1 or more, respectively.) also, Specific examples include those represented by the following structural formulas, but are not limited thereto.

(6) -C_ThreeH₆-N (CH_Three)₃・ Cl  (7) -C_ThreeH₆-N H_Three・ Cl  (9) -C_TwoH_Four-N (CH_Three)₂・ Cl  (11) -C_ThreeH₆-NH-CO-N H_Three・ Cl    Polysiloxane having an ammonium salt as a functional group
As a method for obtaining
Organohalogenated silanes and especially ammonium bases
Polymerization Using Organohalogenated Silanes Having No
Method introduced by copolymerizing in a stage, Olga
Polysiloxy obtained by polymerization using halogenated silane
An organic group having an ammonium salt as a functional group
It can be obtained by a method of partially denaturing. This
Here, instead of the organohalogenated silane, an organoal
Coxysilane may be used. For some compounds,
Can also be obtained as a commercial product.

As inorganic fine particles used for surface treatment of polysiloxane having an ammonium salt as a functional group,
For example, fine particles such as silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, chromium oxide, cerium oxide, antimony trioxide, zirconium oxide, and silicon carbide can be given. . It is preferable that the average particle diameter of the primary particles (particles separated into individual unit particles) of the inorganic part particles be in the range of 3 μm to 2 μm.

As the inorganic fine particles, silica fine particles can be particularly preferably used for improving the fluidity. Silica fine particles are fine particles having Si-O-Si engagement, and may be any of those manufactured by a dry method and a wet method, but those manufactured by a dry method are preferable, and in particular, a silicon halide compound. It is preferable that the fine particles are silica fine particles generated by the vapor phase oxidation of the silica. Further, as the silica fine particles, in addition to silicon dioxide (silica), fine particles made of silicates such as aluminum silicate, sodium silicate, calcium silicate, potassium silicate, zinc silicate, magnesium silicate and the like may be used. Although good, those containing 85% by weight or more of Si ₂ O ₂ are preferable.

As a method for treating the surface of the inorganic fine particles with the polysiloxane having the ammonium salt as a functional group, a known technique can be used. Specifically, for example, the inorganic fine particles are dissolved in a solution in which the polysiloxane is dissolved in a solvent. After dispersing, the solvent is removed by filtration or spray drying, and then dried and cured by heating, or using a fluidized bed apparatus, a solution in which the polysiloxane is dissolved in the solvent is spray-coated on the inorganic fine particles. Then, a method of removing the solvent by heating and drying to form a film, or the like can be used.

The particle size of the specific inorganic fine particles thus obtained is
The average particle size of the primary particles is 3mμ ~ 2μm, especially 5mμ ~
It is preferably within a range of 500 μm. Also, B
The specific surface area by the ET method is preferably from 20 to 500 m ² / g. When the average particle size is too small or the specific surface area is too large, for example, when cleaning is performed using a blade-type cleaning device, inorganic fine particles may easily pass through, and cleaning failure may occur. on the other hand,
When the average particle diameter is too large or the specific surface area is too small, the fluidity of the developer is reduced and the chargeability becomes unstable, and as a result, the durability may be reduced.

When the developer is configured using the specific inorganic fine particles, the specific inorganic fine particles are contained in a state of being attached to the surface of the toner particles by being externally added to and mixed with the toner particle powder. .

The content ratio of the specific inorganic fine particles is 0.5 to
The content is preferably 5% by weight, particularly preferably 0.1 to 2% by weight. When the content ratio of the specific inorganic fine particles is too small, the fluidity of the developer may decrease, and as a result, the triboelectricity of the toner becomes poor, and an appropriate amount of positive charge is given to the toner. And fogging may occur. Further, when the content ratio is excessive, a part of the specific inorganic fine particles may be present in a state of being separated from the toner particles, and as a result, the specific inorganic fine particles may be released from the inner wall of the developing device, the developing sleeve, The toner adheres and accumulates on a blade or the like, and eventually the frictional charging property of the toner becomes poor at an early stage, and it becomes difficult to impart a proper amount of positive charge to the toner, which may cause fog and a decrease in image density. .

The developer of the present invention is basically composed of magnetic toner particles and the specific inorganic fine particles.

The magnetic toner, magnetic particles in a binder resin,
It is a particle powder constituted by containing other additives. The average particle size of the magnetic toner is usually preferably about 5 to 20 μm. As other additives, for example, a coloring agent, a fixing property improving agent, a charge control agent, a cleaning property improving agent, and the like can be used.

The binder resin of the magnetic toner is not particularly limited, and resins conventionally used for this type of application can be used. Specifically, for example, polystyrene resin,
Styrene-acrylic copolymer resin, poly-styrene-
Butadiene resin, polyester resin, epoxy resin and the like can be used. Among them, polystyrene resins, styrene-acrylic copolymers, and polyester resins can be preferably used as those having stable toner charging properties.

As a magnetic material constituting the magnetic toner, a substance which is strongly magnetized in the direction by a magnetic field, for example, iron, ferrite,
Ferromagnetic metals and alloys such as magnetite, nickel, cobalt or other ferromagnetic metals or alloys or compounds containing these elements, alloys that do not contain ferromagnetic elements but become ferromagnetic by appropriate heat treatment, such as An alloy of a kind called a Heusler alloy such as manganese-copper-aluminum or manganese-copper-tin, or particles made of chromium dioxide or the like can be used. The magnetic material is
It is preferable that the average particle diameter is 0.1 to 1 μm,
When such small-diameter magnetic particles are used, they can be uniformly dispersed and contained in the binder resin, and the magnetic properties of the magnetic toner become uniform.

The content ratio of such a magnetic material is preferably from 10 to 70% by weight, and more preferably from 20 to 50% by weight of the magnetic toner. When the content ratio is too small, toner scattering may occur. On the other hand, when the content ratio is too large, the developer layer becomes non-uniform and image unevenness may occur.

As a coloring agent, for example, carbon black, phthalocyanine blue, benzidine yellow, nigrosine dye,
Dyes and pigments such as aniline blue, calco oil blue, chrome yellow, ultramarine blue, Dupont oil red, quinoline yellow, methylene blue chloride, malachite green oxalate, lamp black and rose bengal can be used.

As the charge control agent, for example, an N atom-containing polymer such as a nigrosine dye, a metal complex dye, an ammonium salt compound, an aminotriphenylmethane dye, and a styrene dimethylaminoethyl methacrylate copolymer can be used.

Examples of the fixability improver include polyolefins such as polyethylene and polypropylene, fatty acid metal salts, fatty acid esters and fatty acid ester-based waxes, higher fatty acids,
Higher alcohols, liquid or solid paraffin waxes, amide waxes, polyhydric alcohol esters, silicone varnishes, aliphatic fluorocarbons and the like can be used.

Among them, polyolefin is particularly preferable, and when applied to a heat roller fixing device, fixability and offset resistance can be improved.

Examples of the cleaning improver include fatty acid metal salts such as zinc stearate, calcium stearate, and stearic acid, and polymer fine particles such as fine particles of methyl methacrylate and fine particles of styrene.

In the image formation to which the developing method of the present invention is applied, an organic photoconductor preferably used is, for example, a photoconductor in which a photoconductive semiconductor made of an organic compound is dispersed and contained in a resin binder on a conductive support made of aluminum, stainless steel or the like. It is configured by stacking layers.

As the photosensitive layer, for example, a styrene-methyl methacrylate copolymer, a polycarbonate resin such as an anthranthrone-based compound, a perylene-based derivative, a bisazo-based compound, and a carrier-generating material that generates a charged carrier by absorbing visible light, such as a phthalocyanine-based compound; , A carrier generation layer dispersed and contained in a binder resin such as a silicone resin,
For example, a carrier transporting layer containing a carrier transporting substance that transports carriers generated in a carrier generating layer such as an oxadiazole derivative, a triarylamine derivative, a polyarylalkane derivative, a hydrazone derivative, a stilbene derivative, a styryltriarylamine derivative, or the like. It is preferable to use a function-separated type photosensitive layer formed by combining the above in order to improve the resolution, the cleaning property, and the durability.

Next, a specific developing process for developing an electrostatic latent image using the above-described developer will be described.

As a developer carrier (hereinafter sometimes referred to as a “sleeve”) for supplying the developer to the developing space, the same as a conventional one to which a bias voltage can be applied can be used. A structure in which a rotating magnet body having a plurality of magnetic poles is provided inside a sleeve on which a layer is carried can be preferably used. In such a developer carrier, since the developer layer carried on the surface of the sleeve moves up and down like a spike by the rotation of the rotary magnet, new developer is supplied one after another. In addition, even if the developer layer on the surface of the sleeve has a slight unevenness in the thickness, the effect is sufficiently covered so as not to cause a practical problem due to the spike-like undulation. It is preferable that the transport speed of the developer due to the rotation of the rotating magnet or the rotation of the sleeve is almost the same as or faster than the moving speed of the electrostatic latent image carrier. Further, it is preferable that the transport direction by the rotation of the rotating magnet body and the rotation of the sleeve be the same. The image reproducibility is better in the same direction than in the opposite direction. However, it is not limited to these.

Further, it is preferable that the thickness of the developer layer carried on the developer carrier is uniform, for example, the developer adhered on the developer carrier is sufficiently scraped off by a blade for regulating the thickness. It is preferable to form a uniform layer. The gap between the developer carrier and the electrostatic latent image carrier is several tens to 20
00 μm is preferred, more preferably 50 to 500 μm, and the gap between the developer carrier and the electrostatic latent image carrier is several tens μm.
If it is too narrow, it becomes difficult to form magnetic brush ears that uniformly develop in the developing space, and it is also not possible to supply a sufficient amount of toner particles to the developing space, resulting in stable development. On the contrary, if the gap greatly exceeds 2000 μm, the counter electrode effect is reduced so that a sufficient image density cannot be obtained. The edge effect of increasing toner adhesion also increases.

The thickness of the gap and the thickness of the developer layer should be set so that the magnetic brush ears do not come into contact with the surface of the electrostatic latent image carrier and are as close as possible under the condition where no oscillating electric field is applied. Particularly preferred. This is because it is possible to prevent the toner image from being swept by the magnetic brush and from being fogged.

The oscillating electric field is preferably formed by applying an oscillating bias voltage to the developer carrier. Further, as the bias voltage, it is preferable to use a voltage obtained by superimposing an AC voltage for facilitating separation of toner particles from a DC voltage for preventing toner particles from adhering to non-image portions.

FIG. 1 shows an example of a specific apparatus that can be used for performing the developing step in the developing method of the present invention. In FIG. 1, reference numeral 1 denotes a drum-shaped electrostatic latent image carrier made of a photosensitive member such as an organic semiconductor, which rotates in the direction of an arrow, and forms an electrostatic latent image on the surface by a charging exposure device (not shown). You. Reference numeral 2 denotes a sleeve made of a non-magnetic material such as aluminum, and 3 denotes a plurality of Ns provided inside the sleeve 2.
The sleeve 2 and the magnet body 3 constitute a developer carrier with a magnet body having S magnetism along the circumference. The sleeve 2 and the magnet body 3 are relatively rotatable, and in the illustrated example, the sleeve 2 is rotated in the direction of the arrow, and the magnet body 3 is fixed. The N and S magnetic poles of the magnet body 3 are usually magnetized to a magnetic flux density of 500 to 1500 gauss, and the magnetic force causes the developer D to be composed of brush-like ears brushed on the surface of the sleeve 2.
Layer, ie, a magnetic brush. Reference numeral 4 denotes a regulating blade made of a magnetic or non-magnetic material for regulating the height and amount of the magnetic flash, and 5 denotes a cleaning blade for removing the magnetic brush passing through the developing space A from the sleeve 2. Since the surface of the sleeve 2 comes into contact with the developer D in the developer reservoir 6, the supply of the developer D is performed by the developer D. The numeral 7 agitates the developer D in the developer reservoir 6 to make the components uniform. It is a stirring screw. Developer D in developer pool 6
The toner hopper 8 contains toner particles consumed during development.
The toner particles T are supplied as needed. 9 is a developer pool 6
Is a supply roller having a concave portion on the surface from which toner particles fall. Reference numeral 10 denotes a bias power supply for applying a bias voltage to the sleeve 2 via the protection resistor 11. A bias voltage having an AC component oscillating by the bias power source 10 is applied between the sleeve 1 and the base 1a of the electrostatic latent image carrier 1 grounded. As the bias voltage, for example, a heavy voltage of a DC voltage and an AC voltage is used. The DC component prevents fogging, and the AC component gives a vibration to the magnetic brush, thereby improving the developing effect. For this DC voltage component, a voltage that is generally equal to or higher than the non-image portion potential, for example, 50 to 600 V is used, and for the AC voltage component, the frequency is 100 Hz to 10 kHz.
z, preferably a voltage of 100 V to 5 KV at 1 to 5 kHz is used. Note that the DC voltage component may be lower than the non-image potential when the toner particles contain a magnetic substance. If the frequency of the AC voltage component is too low, the effect of imparting vibration is reduced. Appears. Also, although the voltage of the AC voltage component is related to the frequency, the higher the voltage, the more the magnetic brush vibrates and the more the effect increases,
If it is too high, fogging is likely to occur, and dielectric breakdown such as lightning strike development is likely to occur.

In the above-described apparatus, when the gap between the sleeve 2 and the electrostatic image carrier 1 is set so as to be in the range of several tens to 2000 μm, and the latent image on the electrostatic latent image carrier 1 is developed. The magnetic brush formed on the surface of the sleeve 2
As the magnetic flux density on the surface changes with the rotation of, it moves on the sleeve 2 while oscillating, thereby stably and smoothly passing through the gap with the electrostatic latent image carrier 1. In this case, a uniform developing effect is given to the surface of the electrostatic latent image carrier 1, so that an image having a high image density can be stably obtained.

As described above, an example of the apparatus that can be used in the developing method of the present invention has been described with reference to FIG. 1, but the present invention is not limited to this. For example, even if several electrode wires are stretched around the developing area between the developer carrier and the electrostatic latent image carrier and a voltage oscillating is applied to the electrode wires, the magnetic brush is vibrated to give a vibration effect. Can be improved. In this case, a DC bias voltage may be applied to the developer carrier, or a vibration voltage having a different frequency may be applied. Further, the developing method of the present invention can be similarly applied to reversal development and the like. In that case, the DC voltage component is set to a voltage substantially equal to the receiving potential in the non-image background portion of the electrostatic latent image carrier. Further, the developing method of the present invention can be applied to a case where an image to be developed is a magnetic latent image.

FIG. 2 shows an example of an image forming apparatus which can be suitably used for forming an image by applying the developing method of the present invention.

Reference numeral 1 denotes an organic photoreceptor for forming an electrostatic latent image, and the organic photoreceptor 1 has a rotating drum shape. Around the organic photoreceptor 1, a corona charger 21, an exposure optical system 22,
A developing device 23, an electrostatic transfer device 24, a separator 25, and a blade type cleaning device 26 are arranged.

In the above-described apparatus, the developing surface of the organic photoconductor 1 is charged to a uniform potential by the corona charger 21 and then imagewise exposed by the exposure optical system 22 so that the original is printed on the developing surface of the organic photoconductor 1. A corresponding electrostatic latent image is formed. And developing device
The electrostatic latent image is developed by 23 to form a toner image corresponding to the original. The toner image on the organic photoreceptor 1 is electrostatically transferred to a transfer paper 28 by an electrostatic transfer device 24, and
The toner image on 22 is heated and fixed by a heat roller fixing device 27 to form a fixed image. On the other hand, the organic photoreceptor 1 that has passed through the electrostatic transfer unit 24 is rubbed on its surface by the blade-type cleaning unit 26 so that the toner remaining on the surface is scraped off. After that, the charging process by the corona charger 21 is performed again.

Specific Examples Hereinafter, specific examples of the present invention will be described, but the present invention is not limited to these examples.

(Production of binder resin) (1) Production of vinyl polymer A Styrene 83.5 parts Butyl acrylate 15 parts Divinylbenzene 1.5 parts Benzoyl peroxide 5 parts In a four-necked flask equipped with a stirrer, a thermometer and a nitrogen inlet tube, 600m water containing 2% by weight of tricalcium phosphate and 0.2% by weight of sodium dodecylbenzenesulfonate
l, put the inside of the reaction vessel into a nitrogen gas atmosphere via a nitrogen introduction pipe, add 200 g of the above composition at room temperature with stirring, suspend, and then raise the temperature to 30 ° C. The reaction was performed for 8 hours. After completion of the reaction, the system was cooled, hydrochloric acid was added, filtration and washing were repeated to remove tricalcium phosphate and sodium dodecylbenzenesulfonate, followed by drying to obtain a non-linear vinyl polymer. . This is designated as vinyl polymer A.

The softening point Tsp of this vinyl polymer A was 131 ° C., and the glass transition point Tg was 65 ° C.

(2) Production of vinyl polymer B 74.5 parts of styrene 3.5 parts of α-methylstyrene 20 parts of n-butyl acrylate 2 parts of divinylbenzene 4 parts of azobisisobutyronitrile 4 parts Vinyl polymer A other than using the above composition In the same manner as in the above, a non-linear vinyl polymer was obtained. This is designated as vinyl polymer B.

The softening point of this vinyl polymer B was 128 ° C. for T sp and 62 ° C. for the glass transition point Tg.

(Production of Toner) (1) 60 parts by weight of magnetic toner T1 "vinyl polymer A" and magnetic substance "BL-50"
0 ”(manufactured by Titanium Industry Co., Ltd.) and 35 parts by weight of polypropylene“ Viscole 660P ”(manufactured by Sanyo Chemical Industry Co., Ltd.)
"Nigrosine SO" (manufactured by Orient Chemical Industry Co., Ltd.), 2 parts by weight, are mixed by a V-type blender, melt-kneaded by two rolls, then cooled, coarsely ground by a hammer mill, and finely ground by a jet mill. And then classified by an air classifier, the average particle size is 11.0 μm, and the softening point is 135 ° C.
Was obtained. This is referred to as “magnetic toner T1”.

(2) Magnetic toner T2 In the image of the magnetic toner T1, the "vinyl polymer A"
In the same manner as above, except that 58 parts by weight of "vinyl polymer B" and 3 parts by weight of polyethylene "Mitsui High Wax 400P" were used instead of 3 parts by weight of polypropylene and 3 parts by weight of polypropylene, the average particle size was 10.5 μm, and the softening point was A toner at 133 ° C. was obtained. This is referred to as “magnetic toner T2”.

(3) Magnetic toner T3 The same procedure as in the production of magnetic toner T1 except that instead of 60 parts by weight of vinyl polymer A and 3 parts by weight of polypropylene, 53 parts by weight of vinyl polymer B and 8 parts by weight of "polyester P3" were used. The softening point is 128 ° C and the average particle size is 11.3μ
m was obtained. This is referred to as “magnetic toner T3”.

(Production of Inorganic Fine Particles) (1) Inorganic Fine Particles A (for the Present Invention) A polysiloxane having the following ammonium salt as a functional group as a constituent unit thereof was dissolved in xylene to prepare a treatment liquid.

Next, silica fine particles “Aerosil 200” (manufactured by Nippon Aerosil Co., Ltd.) are put into a mixer, and the above-mentioned polysiloxane is sprayed on the silica fine particles at a ratio of 5% by weight. Then, xylene as a solvent was removed at a temperature of 200 ° C. for 5 hours with stirring to obtain inorganic fine particles obtained by surface-treating polysiloxane having an ammonium salt as a functional group. This is referred to as “inorganic fine particles A”. This inorganic fine particle A
The average particle size of the primary particles was 12 mμ, and the specific surface area measured by the BET method was 115 m ² / g.

(2) Inorganic fine particles B (for the present invention) As a constituent unit thereof, a polysiloxane having the following ammonium salt as a functional group was dissolved in xylene to prepare a treatment liquid.

Next, silica fine particles "Aerosil 300" (manufactured by Nippon Aerosil Co., Ltd.) were placed in a mixer, and the above-mentioned polysiloxane was sprayed to the silica fine particles at a ratio of 17% by weight. In the same manner, surface-treated inorganic fine particles were obtained. This is referred to as “inorganic fine particle B”. The inorganic fine particles B have an average primary particle diameter of 7 m.
The specific surface area by μ and BET method was 126 m ² / g.

(3) Inorganic fine particles C (for the present invention) A polysiloxane having the following ammonium salt as a functional group was dissolved in xylene to prepare a treatment liquid.

Next, silica fine particles “Aerosil 200” (manufactured by Nippon Aerosil Co., Ltd.) were put into a mixer, and the above-mentioned polysiloxane was sprayed at a ratio of 10% by weight to the silica fine particles. The same treatment as in the production was performed to obtain surface-treated inorganic fine particles. This is called "inorganic fine particle C"
And The inorganic fine particles C have an average primary particle size of 12
mμ, the specific surface area measured by the BET method was 93 m ² / g.

(4) Inorganic fine particles D (for comparison) Silica fine particles “Aerosil 200” (manufactured by Nippon Aerosil Co., Ltd.) are placed in a closed Henschel mixer heated to 100 ° C., and an amino group-containing silicone oil is added to the silica fine particles with isopropyl alcohol. Solution (viscosity: 1200 cps, amino equivalent: 3500) is sprayed at a high speed while spraying at a rate such that the amino group-containing silicone oil becomes 2.0% by weight, and then dried at a temperature of 150 ° C. to give the amino group-containing silicone oil. Comparative inorganic fine particles whose surfaces were treated with silicone oil were obtained. This is called "inorganic fine particle D"
And

(5) Inorganic fine particles E (for comparison) Silica fine particles “Aerosil 200” (manufactured by Nippon Aerosil Co., Ltd.) are placed in a closed Henschel mixer heated to 70 ° C., and an amino group-containing silane coupling agent is added to the silica fine particles. A solution obtained by dissolving a certain γ-aminopropyltriethoxysilane in alcohol is stirred at a high speed while spraying at a ratio such that the amino group-containing silane coupling agent becomes 5.0% by weight, and then dried at a temperature of 120 ° C. Thus, comparative inorganic fine particles whose surfaces were treated with the amino group-containing silane coupling agent were obtained. This is referred to as “inorganic fine particles E”.

(Adjustment of Developer) The inorganic fine particles were added to the magnetic toner at the ratios shown in Table 1, and these were mixed with a Henschel mixer to cause the specific inorganic fine particles to adhere to the surface of the magnetic toner particles, thereby developing the toner of the present invention. Agents 1 to 4 and Comparative developers 1 and 2 were obtained.

(Organic Latent Image Carrier) (1) Organic Latent Image Carrier P1 A negatively chargeable two-layer photosensitive layer formed by using an anthranthrone-based face derivative as a carrier-generating material is used to form a rotating drum-shaped aluminum conductive material. The organic latent image carrier was laminated on the support. This is called `` organic latent image carrier P1 ''
And

(2) Organic Latent Image Carrier P2 An organic latent image carrier P2 was constructed in the same manner as the organic latent image carrier P1, except that a bisazo pigment was used as a carrier generating substance and a hydrazone derivative was used as a carrier transporting substance. This is referred to as “organic latent image carrier P2”.

(3) Organic latent image carrier P3 An organic latent image carrier was prepared in the same manner as the organic latent image carrier P1 except that a bisazo pigment was used as a carrier generating substance and a styryltriarylamine derivative was used as a carrier transporting substance. Configured. This is designated as “organic latent image carrier P3”.

<Actual photo test> An organic latent image carrier for forming a negative charge latent image, a developing device shown in FIG. 1, a corona transfer device for generating corona discharge,
A cleaning device having a cleaning blade made of urethane rubber, a heat roller having a diameter of 30φ formed of Teflon (polytetrafluoroethylene manufactured by DuPont) and a silicone rubber “KE-1300RTV” formed of a surface layer
The relative humidity was measured using a remodeled electrophotographic copier "UBix1200" (manufactured by Konishi Roku Kogyo Co., Ltd.) equipped with a heat roller fixing device comprising a backup roller formed by Shin-Etsu Chemical Co., Ltd. Under a high-humidity environment of 80%, a real-image test for forming a copy image was performed 150,000 times, and the following items were evaluated. The photoconductor was replaced at 80,000 times.

The developer and photoreceptor used in each of the examples and comparative examples are as shown in Table 1 above.

The other development conditions in the above-mentioned actual shooting test are as follows. That is, the surface potential (maximum potential) during charging of the organic latent image carrier is -800 V, the DC bias voltage applied to the developing sleeve is -150 V, and the AC bias is 0.
The gap (Dsd) between the photoreceptor and the developing sleeve in the developing space of 5 to 2 KV (2 kHz) is 400 µm, the distance (Hcut) between the developing sleeve at the tip of the regulating blade is 300 µm, and the magnet is a fixed type. The magnetic flux density on the surface of the developing sleeve is 800
Gauss. In Comparative Example 3, contact development was performed without applying an oscillating electric field and H cut: 420 μm.

 The results are shown in Table 2 below.

Fog Using a “Sakura Densitometer” (manufactured by Konishi Roku Kogyo Co., Ltd.), the density was determined by measuring the relative density of a white background portion having a document density of 0.0 with respect to the copied image. In addition, 0.0
And In the evaluation, the case where the relative concentration was less than 0.01 was evaluated as “○”, the case where the relative concentration was 0.01 or more and less than 0.03 was evaluated as “Δ”, and the case where the relative concentration was 0.03 or more was evaluated as “×”.

Image density decrease Using "Sakura Densitometer" (manufactured by Konishi Roku Kogyo Co., Ltd.), measure the relative density of a white background portion with a document density of 0.0 to the copied image. Indicated.

Image quality The copied image was visually judged from two viewpoints of image unevenness and sharpness. The evaluation was “場合” for good, “△” for slightly poor but practical level, and “×” for poor and practically problematic.

Cleanability After repeatedly forming an image, the surface of the organic latent image carrier immediately after being cleaned by the cleaning blade is visually observed, and is determined based on the presence or absence of an attached matter and a scratch on the surface of the organic latent image carrier. did. The evaluation was “○” when the image was good and clear with almost no deposits or scratches, “△” when it was slightly observed but was at a practical level, and black spots on the image where many deposits or scratches were observed. In the case where black streaks or black streaks were recognized and there was a problem in practice, it was rated "x".

Fluidity of the developer Visually observe the developer in the developing unit, and if the fluidity is good, mark it as ○ .If the fluidity is not good but it is at a practical level, mark it as △. Indicates that there is a problem with "x".

Resolution According to JIS Z 4916, a chart was used in which 4.0, 5.0, 6.3, and 8.0 horizontal lines at equal intervals per mm were provided as a grade, and the grade in which the horizontal lines could be distinguished was displayed as the resolution.

Durability The number of copies for obtaining a clear image is shown.

As can be seen from the results in Table 2, in Examples 1 to 4 according to the developing method of the present invention, the organic latent image carrier was formed by the developing method applying an oscillating electric field even under high temperature and high humidity environmental conditions. Fogged negative charge latent image, can perform image development with good definition and resolution without image unevenness and image density reduction, and in the cleaning process, clean well with a cleaning blade having a simple structure As a result, a clear image could be formed even after performing the image forming process for 150,000 times without causing a cleaning failure, and the durability was excellent. Further, it is possible to obtain an image having good fixability without generating offset.

It is apparent from Table 2 that the comparative example has more serious problems in practical use than the above examples.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of an electrostatic latent image developing device that can be used to carry out the present invention, and FIG. 2 is a diagram for performing an image forming method to which the developing method of the present invention can be applied. FIG. 2 is a cross-sectional view illustrating an example of an image forming apparatus that can be suitably used. 1 electrostatic latent image carrier 2 developer carrier (sleeve) 3 magnet body 4 regulating blade 5 cleaning blade 6 developer pool 10 bias power supply 21 ... Corona charger 22 ... Exposure optical system, 23 ... Developer 24 ... Electrostatic transfer unit, 25 ... Separator 26 ... Blade type cleaning device 27 ... Heat roller fixing device, 28 ... Transfer paper

Claims (2)

(57) [Claims] An image forming method comprising the steps of: generating an electric field in a developing area, developing an electrostatic latent image formed on a surface of a photoreceptor with a developer, and cleaning the image with a cleaning member; An electric field, the photoconductor is an organic photoconductor, the electrostatic latent image is a negative electrostatic latent image, the cleaning member is a cleaning blade made of urethane rubber, and the developer has magnetic particles. The developer is obtained by externally adding and mixing inorganic fine particles obtained by surface-treating a polysiloxane containing a structural unit represented by the following formula (A) having an ammonium salt as a functional group to a magnetic toner particle containing the toner. Characteristic image forming method. Formula (A) (Where R ₁ is a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, or R ₂ represents a bonding group or a mere bond, R ₃ , R ₄ and R ₅ each represent a hydrogen atom, an alkyl group or an aryl group, and X represents a halogen atom. Each group represented by R _{1 to} R ₅ includes those having a substituent. ) 2. An image forming method according to claim 1, wherein said inorganic fine particles are silica fine particles.