JPH0954499A - Image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming method by which high picture quality can be stably obtd. for a long time without wear, damages or deterioration due to ozone of a photoreceptor even when image forming is repeated by a two-component developer method. SOLUTION: An electrostatic latent image on an org. photoreceptor 10 is developed with a two-component developer 138. In this image forming method, the outermost surface layer of the org. photoreceptor 10 contains inorg. fine particles. The method has the following features. (1) The center of the main magnet 135 in a developer layer carrying body 133 is tilted by 2-20 deg. from the line which connects the centers of the developer carrying body 133 and the photoreceptor 10. Or, (2) the carrier of the two-component developer 138 is a resin-coated ferrite or magnetite carrier. The moving rate (Vs) of the developer layer carrying body 133 is >=150mm/sec, and the ratio Vs to the moving rate (Vp) of the photoreceptor (Vs/Vp) is 1.5 to 3.5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming method used for color or monochrome copying machines, printers, facsimiles and the like.

[0002]

2. Description of the Related Art In the electrophotographic image forming method of the Carlson method, after uniformly charging the surface of a photoreceptor, the charge is erased imagewise by exposure to form an electrostatic latent image. After developing the image with toner, the toner image is transferred to paper or the like and then fixed.

On the other hand, the photoreceptor is cleaned and discharged to remove the toner remaining on the surface, and is repeatedly used for a long period of time. Therefore, as an electrophotographic photoreceptor,
In addition to the electrophotographic characteristics such as good charging characteristics and good sensitivity and small dark decay, in addition to physical characteristics such as printing durability, abrasion resistance, moisture resistance after repeated use, and ultraviolet rays during exposure, etc. Good resistance (environmental resistance) is also required.

Recently, selenium, zinc oxide, cadmium sulfide, and other inorganic photoconductors are preferred as electrophotographic photoconductors in view of pollution control, and substances exhibiting various functions in accordance with desired characteristics are selected from a wide range. There is a trend to put the organic photoconductor into practical use.

Conventionally, such an organic photoreceptor is mainly used for negative charging. As described in JP-A-60-247647, a thin charge generating layer is provided on a support and a relatively thick layer is formed thereon. A structure in which a charge transport layer is provided is adopted. However, since the charge transport layer is composed of a polymer binder, a carrier transport material, etc., it is worn away by the developing sleeve, transfer paper, cleaning member, etc. during use, and gradually loses its initial charge characteristics and light attenuation characteristics. There was a problem that it would not be obtained.

As a countermeasure against this, it has been proposed that the outermost surface layer (uppermost layer) contains colloidal silica or organic fine particles. However, it has been found that since particles having a large specific surface area are present on the outermost surface, discharge active species such as ozone are likely to be adsorbed, which causes a problem such as image blur. This tendency is particularly strong when the corona discharge method, which generates a large amount of discharge active species, is used.

The inventors of the present invention have previously incorporated inorganic particles having a relatively large particle size into the uppermost layer of the photoreceptor,
It has been found that the surface can have strength.

On the other hand, the developing system includes a system using a one-component developer and a system using a two-component developer using a carrier and a toner. However, the charging potential of the developer is high and therefore the image performance is stable. Is advantageously a two-component developer system. However, in the two-component developer system, one carrier is used.
Since relatively large magnetic particles having a diameter of about 00 μm are used, and the developer spikes made of the magnetic particles rub against the photosensitive member during development, wear of the photosensitive member is increased. Further, if the carrier adheres to the surface of the photoconductor, it tends to be rubbed against the surface of the photoconductor by a blade or the like at the time of cleaning to cause damage.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and to prevent abrasion and damage of a photoreceptor and deterioration due to ozone even if images are repeatedly formed by a two-component developer system. An object of the present invention is to provide an image forming method capable of stably obtaining high image quality over a long period of time.

[0010]

The object of the present invention is attained by adopting one of the following constitutions.

[1] In an image forming method of developing an electrostatic latent image on an organic photoreceptor with a two-component developer, the outermost surface layer of the organic photoreceptor contains inorganic fine particles, and An image forming method, wherein the center of the main magnet is tilted by 2 to 20 ° with respect to the line connecting the center of the developer layer carrier and the center of the photoreceptor.

[2] The organic photoreceptor has a charge generation layer on a conductive support and a plurality of charge transport layers laminated thereon, and the outermost surface layer is a charge transport layer. The image forming method according to [1].

[3] The image forming method as described in [1] or [2], wherein the inorganic fine particles have a Mohs hardness of 5 or more and a volume average particle diameter of 0.05 to 2.0 μm.

[4] The strength of the photosensitive layer of the organic photoreceptor is 200 g using a diamond needle having a tip radius of 0.3 mm.
Depth of 0.1-1.0 μm when vertical load is applied
The image forming method as described in [1], [2] or [3].

[5] In an image forming method of developing an electrostatic latent image on an organic photoconductor with a two-component developer, the outermost surface layer of the organic photoconductor contains inorganic fine particles, and the carrier of the two-component developer is contained. Is a ferrite or magnetite resin coating carrier, and the moving speed (V
s) is 150 mm / sec or more, and the ratio (Vs / Vp) to the moving speed (Vp) of the photoconductor is 1.5 to 3.5.

[6] The organic photoreceptor has a charge generation layer on a conductive support and a plurality of charge transport layers laminated thereon, and the outermost surface layer is a charge transport layer. [5] The image forming method described.

[7] The image forming method according to [5] or [6], wherein the inorganic fine particles have a Mohs hardness of 5 or more and a volume average particle diameter of 0.05 to 2.0 μm.

[8] The strength of the photosensitive layer of the organic photoreceptor is 200 g using a diamond needle having a tip radius of 0.3 mm.
Depth of 0.1-1.0 μm when vertical load is applied
The image forming method according to [5], [6] or [7].

When an image is formed using a combination of an organic photoconductor and a two-component developer, the initial image is good, but the photoconductor is worn at a high rate, so that the image tends to be deteriorated, and the image is tens of thousands to tens. In the field of medium- and high-speed copying machines and printers that perform image formation, image quality gradually deteriorates, and further improvements have been demanded.

Particularly in image formation by two-component development using ferrite or the like as a carrier, the spikes at the latent image developing position are soft and good image quality can be obtained, but the saturation magnetization value is lower than that of iron powder or the like. Therefore, carrier scattering is likely to occur, and the photoreceptor is likely to be scratched.

As a method of relatively reducing the occurrence of carrier scattering, Japanese Patent Laid-Open No. 61-17775 discloses a main magnet in a developing sleeve in which the center position of the magnetic flux of the main magnet is 2 to 15 degrees upstream from the photoconductor opposing position. It has been proposed to change the magnetic force when entering and exiting the tilted development zone. However, even if these process improvements are added, the amount of carrier scattering cannot be reduced to zero, and when a conventional organic photoreceptor having a weak surface film strength is used, the durability of tens of thousands to hundreds of thousands of image formation can be achieved. In the medium- and high-speed copying machine and printer markets that require high performance, the reality is that they have not achieved sufficient reliability.

Particularly, the carrier has a saturation magnetization value of 100e.
In the two-component development method using a ferrite carrier of mu / g or less, carrier scattering easily occurs when the inclination of the developing main magnetic pole becomes large, and such carrier scattering occurs in the image forming method using the conventional organic photoconductor. When it occurs, the carrier is sandwiched between the cleaning blade and the photoconductor in the cleaning process, and the carrier has scratched the surface of the photoconductor.

As described above, it has been difficult to secure a good image over a large number of sheets by the conventional image forming method using an organic photoconductor.

Further, in the medium-high speed machine, the developing time is shortened, and in order to achieve sufficient development, the rotation speed (Vs) of the developing sleeve that conveys the developer is set higher than the rotation speed of the photoconductor. Are often used, and carrier scattering tends to occur more and more. In order to prevent this, if a carrier having a large saturation magnetization such as an iron powder carrier is used, the magnetic brush becomes rigid, and image defects such as sweep marks are likely to occur in a high speed medium-high speed machine. Therefore, there has been a demand for an image forming method that uses a carrier such as ferrite that enables a magnetic brush having an appropriate hardness and that does not damage the photoconductor and that can guarantee a good image quality over many sheets.

The present invention has been made to meet these needs.

The inorganic particles contained in the outermost surface layer of the electrophotographic photosensitive member of the present invention are hard particles having a Mohs hardness of 5 or more because they need to have high film strength and have strength themselves. It is assumed that the performance will not be adversely affected.

Examples of such inorganic particles include oxides such as cerium oxide, chromium oxide, aluminum oxide, magnesium oxide, silicon oxide, tin oxide, zirconium oxide, iron oxide and titanium oxide; calcium sulfate, barium sulfate and sulfuric acid. Sulfates such as aluminum; silicates such as calcium silicate and magnesium silicate; nitrides such as boron nitride and titanium nitride; silicon carbide, titanium carbide,
Carbides such as boron carbide, tungsten carbide, and zirconium carbide; borides such as zirconium boride and titanium boride, and the like can be used, and one of these can be used, or two or more can be used as necessary.

The inorganic particles have a volume average particle size of 0.05 to
2.0 μm, preferably a ratio of major axis / minor axis of 2.0
Less than substantially spherical particles.

The volume average particle diameter of the inorganic particles is 0.05 μ
If it is less than m, sufficient mechanical strength of the surface of the photoreceptor cannot be obtained, and the surface area of the particles becomes large. As a result, the amount of adsorbed water increases and the surface of the photoreceptor wears and is damaged during repeated image formation, resulting in electron Photo performance deteriorates. On the other hand, if it exceeds 2.0 μm, the surface roughness of the photoconductor becomes large, and the cleaning blade is worn or damaged to deteriorate the cleaning characteristics, resulting in poor cleaning and easy occurrence of image blur.

The above-mentioned inorganic particles being substantially spherical means that the surface shape can be distinguished by an electron microscope (diameter 1 to 10 mm).
When expanded to, the particles are not considered to have an indefinite shape, but are considered to be spherical with the ratio of major axis / minor axis less than 2.0. In that case, the wear coefficient of the surface of the photoconductor can be reduced. In addition,
The volume average particle diameter of the inorganic fine particles is measured by a laser diffraction / scattering type particle size distribution measuring apparatus LA-700 (manufactured by Hikiba Seisakusho).

The inorganic particles are preferably hydrophobized with a hydrophobizing agent such as a titanium coupling agent, a silane coupling agent, a polymeric fatty acid or a metal salt thereof.

Examples of the titanium coupling agent include tetrabutyl titanate, tetraoctyl titanate, isopropyl triisostearoyl titanate, isopropyl tridecylbenzene sulfonyl titanate, bis (dioctyl pyrophosphate) oxyacetate titanate and the like. Further, as the silane coupling agent, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-β- (N-vinylbenzylaminoethyl) γ-aminopropyltrimethoxysilane hydrochloride, hexamethyldisilazane, methyltrimethoxysilane, butyltrimethoxysilane, isobutyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, decyltri Methoxysilane,
Examples thereof include dodecyltrimethoxysilane, phenyltrimethoxysilane, o-methylphenyltrimethoxysilane, p-methylphenyltrimethoxysilane and the like.

The fatty acids include undecyl acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid,
Long-chain fatty acids such as pentadecanoic acid, stearic acid, heptadecanoic acid, arachidic acid, montanic acid, oleic acid, linoleic acid, and arachidonic acid are mentioned, and their metal salts are zinc, iron, magnesium, aluminum, calcium, sodium, lithium. Salts with metals such as.

These compounds are preferably added in an amount of 1 to 10% by weight with respect to the above-mentioned inorganic fine particles for coating, and preferably 3 to 7% by weight. Further, these materials can be used in combination, and the surface of the inorganic fine particles is usually covered with a monomolecular layer or a layer close thereto.

In the present invention, silica particles are particularly preferably used as the inorganic fine particles contained in the outermost surface layer of the photoconductor, and silica particles having low hygroscopicity and few active hydroxyl groups on the surface are preferably used. To be

In the present invention, these inorganic fine particles are contained at least in the outermost surface layer of the electrophotographic photosensitive member together with the binder. The proportion of the inorganic fine particles in the outermost surface layer is usually 0.5% by weight or more and 200% by weight or less with respect to the binder. Hereinafter, it is preferably used in an amount of 1% by weight or more and 100% by weight or less.

The outermost surface layer of the present invention may be a photosensitive layer positioned on the outermost surface of the electrophotographic photosensitive member, or may be a protective layer laminated thereon.

The photosensitive layer of the electrophotographic photosensitive member of the present invention in which the inorganic particles are contained in the outermost surface layer may be an inorganic photosensitive member using selenium, amorphous silicon, cadmium sulfide, etc., but is preferably Organic charge generation material (CG
M) and a charge transport material (CTM). The layer structure of the organic photoreceptor is shown in FIG.

FIG. 1A shows an intermediate layer 2 on a conductive support 1.
Through the charge generation material (CGM) and charge transport material (CT
M) is a photoreceptor having a single-layered photosensitive layer 6, and FIG. 1B contains a charge transport material (CTM) as a main component on an electrically conductive support 1 through an intermediate layer 2. And a charge generation layer (CGL) 4 containing a charge generation material (CGM) as a main component in this order.
(C) is a photoconductor having a photoconductive layer 6 formed by laminating a charge generation layer (CGL) 4 and a charge transport layer (CTL) 3 in this order on an electroconductive support 1 with an intermediate layer interposed therebetween.

Further, FIGS. 1 (d), (e) and (f) respectively show a protective layer 5 on the photosensitive layer of FIGS. 1 (a), (b) and (c).
Are shown. Above (a), (b), (c),
Each of (d), (e) and (f) shows a typical constitution of the organic photoconductor, and the present invention is not limited to these layer constitutions. For example, the intermediate layer 2 shown in these figures may be omitted if not necessary.

Of the above-mentioned layer constitutions, the most preferable embodiment of the present invention is that the protective layer 5 is further laminated on the photosensitive layer as shown in (d), (e) and (f), and In which the inorganic particles of the present invention are contained.

The protective layer, when provided, is composed of at least a resin and the inorganic particles of the present invention, but has a layer structure composed of so-called plural charge transport layers containing a charge transport substance (CTM) in the protective layer. Things are more preferable. By including a charge transport material (CTM) in these protective layers, an increase in the residual potential and a decrease in sensitivity due to repeated use of the electrophotographic photoreceptor can be prevented.

The film strength of the outermost surface layer of the photoconductor was measured using a HEIDON-18 type surface property measuring instrument (manufactured by Shinto Kagaku Co., Ltd.). That is, tip radius 0.3m
A vertical load of 200 g was applied using a diamond needle of m, the needle was moved at a speed of 10 mm / sec to make a scratch, and the depth of the scratch was measured with a laser microscope (Lase).
(made by rtec), and the depth (μm) was defined as the film strength.

Examples of the charge generating substance (CGM) contained in the photosensitive layer 6 of each of the photoreceptors shown in FIGS. 1A to 1F are, for example, phthalocyanine pigment, polycyclic quinone pigment, azo pigment,
Perylene pigments, indigo pigments, quinacridone pigments, azurenium pigments, squarylium dyes, cyanine dyes, pyrylium dyes, thiopyrylium dyes, xanthene dyes,
Triphenylmethane dye, styryl dye and the like,
These charge generating materials (CGM) may be layered alone or with an appropriate binder resin.

Examples of the charge transport material (CTM) contained in the photosensitive layer 6 include oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives,
Imidazolone derivatives, imidazoline derivatives, bisimidazolidine derivatives, styryl compounds, hydrazone compounds,
Benzidine compound, pyrazoline derivative, stilbene compound, amine derivative, oxazolone derivative, benzothiazole derivative, benzimidazole derivative, quinazoline derivative, benzofuran derivative, acridine derivative, phenazine derivative, aminostilbene derivative, poly-N-vinylcarbazole, poly-1- Vinylpyrene, poly-9-
Vinyl anthracene and the like can be mentioned. These charge transport materials (CTM) are usually layered with a binder.

Among these, particularly preferable charge transporting substances (CTM) are compounds represented by the following general formula.

[0047]

Embedded image

(In the formula, Ar ₁ , Ar ₂ and Ar ₄ each represent a substituted or unsubstituted aromatic hydrocarbon group or heterocyclic group,
Ar ₃ represents a substituted or unsubstituted divalent aromatic hydrocarbon group or heterocyclic group, and R ₂ represents a hydrogen atom or a substituted or unsubstituted aromatic hydrocarbon group or heterocyclic group. n is 1 or 2. Ar ₄ and R ₂ may combine with each other to form a ring. )

[0049]

Embedded image

(In the formula, R ₃ and R ₄ each represent a substituted or unsubstituted aromatic hydrocarbon group, a heterocyclic group or an alkyl group, which may be linked to each other to form a ring. R ₅ is hydrogen. An atom or a substituted or unsubstituted aromatic hydrocarbon group, a heterocyclic group or an alkyl group is represented, Ar ₅ is a substituted or unsubstituted aromatic hydrocarbon group or a heterocyclic group, and m is 0 or 1.
It is. )

[0051]

Embedded image

(Wherein Y is a substituted or unsubstituted phenyl group,
Naphthyl group, Piriniru group, a fluorenyl group, a carbazolyl group, a diphenyl group, and 4,4'-alkylidene-diphenyl group, Ar _6, Ar ₇ are each substituted, an unsubstituted aromatic hydrocarbon group or a heterocyclic group. l represents an integer of 1 to 3. )

[0053]

Embedded image

(In the formula, Ar ₈ , Ar ₉ , Ar ₁₀ and Ar ₁₁ each represent a substituted or unsubstituted aromatic hydrocarbon group or a heterocyclic group, and Ar ₁ , Ar ₂ and Ar ₃ are as described above. Among these, specific compound examples preferably used in the photoreceptor of the present invention are shown below.

[0055]

Embedded image

[0056]

[Chemical 6]

[0057]

[Chemical 7]

[0058]

Embedded image

[0059]

Embedded image

[0060]

Embedded image

The binder resin contained in the charge generation layer (CGL) and charge transport layer (CTL) is a polyester resin, polystyrene resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polycarbonate resin. , Polyvinyl butyral resin, polyvinyl acetate resin, styrene-butadiene resin, vinylidene chloride-acrylonitrile copolymer resin, vinyl chloride-maleic anhydride copolymer resin, urethane resin, silicone resin, epoxy resin, silicone-alkyd resin, phenol resin , Polysilane resin, polyvinyl carbazole and the like.

The binder resin contained in the uppermost layer of each of the photoreceptors shown in FIGS. 1 (a) to 1 (f) is preferably resistant to mechanical impact and has high abrasion resistance, and does not impair electrophotographic performance. Things are good. Preferred binder resins include polycarbonate resins having a structural unit represented by the following general formula (I), (II), (III) or (IV).

[0063]

Embedded image

(Wherein R _{1 to} R ₈ are hydrogen atoms, halogen atoms, substituted or unsubstituted alkyl groups having 1 to 10 carbon atoms, cycloalkyl groups or aryl groups, and Z is 4 to 11).
A saturated or unsaturated carbocyclic residue having 9 carbon atoms, R ₉ is an alkyl or aryl group having 1 to 9 carbon atoms. )

[0065]

[Chemical 12]

(In the formula, R ₁₁ to R ₁₈ each independently represents a hydrogen atom, a halogen atom, an alkyl group or an aryl group.)

[0067]

Embedded image

(In the formula, R _{21 to} R ₂₈ each independently represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a cycloalkyl group, or an aryl group.)

[0069]

Embedded image

(In the formula, R _{31 to} R ₄₆ each independently represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group or an aryl group, and k and m are positive integers and k / m Is selected to be 1 to 10.) The polycarbonate resin having the structural unit represented by the general formula is preferably one having a weight average molecular weight of 30,000 or more.

Next, as a solvent or a dispersion medium used when forming each of the layers, n-butylamine, diethylamine, ethylenediamine, isopropanolamine,
Triethanolamine, triethylenediamine, N, N
-Dimethylformamide, acetone, methyl ethyl ketone, methyl isopropyl ketone, cyclohexanone, benzene, toluene, xylene, chloroform, dichloromethane, 1,2-dichloroethane, 1,2-dichloropropane, 1,1,2-trichloroethane, 1,1,1 −
Examples thereof include trichloroethane, trichloroethylene, tetrachloroethane, tetrahydrofuran, dioxane, methanol, ethanol, isopropinal, ethyl acetate, butyl acetate, dimethyl sulfoxide, and methyl cellosolve. The present invention is not limited to these, but when a ketone solvent is used, the sensitivity and potential change during repeated use are further improved. These solvents can be used alone or as a mixture of two or more solvents.

In the present invention, the weight ratio of the charge generating substance to the binder resin in the charge generating layer is preferably 1: 5 to 5: 1. However, the binder resin is not always necessary. The thickness of the charge generation layer is preferably 5 μm or less, and particularly 0.0
5 to 2 μm is preferred.

The charge transport layer is formed by dissolving the above charge transport substance and the binder resin in an appropriate solvent, and coating and drying the solution. The mixing ratio of the charge transport material and the binder resin is preferably 10: 1 to 1:10 by weight.

The thickness of the charge transport layer is 5 to 50 μm,
It is particularly preferably 10 to 40 μm.

When the photoreceptor is a single layer type, it can be obtained by coating and drying a solution in which the above-mentioned charge generating substance and charge transporting substance are dispersed and dissolved in a binder resin.

Next, as the electroconductive support of the electrophotographic photosensitive member of the present invention, 1) a metal plate such as an aluminum plate or a stainless plate, 2) aluminum, palladium or gold on a support such as paper or a plastic film. 3) A thin metal layer such as is provided by lamination or vapor deposition, 3) A layer of a conductive compound such as a conductive polymer, indium oxide or tin oxide is provided by coating or vapor deposition on a support such as paper or plastic film The thing etc. are mentioned.

The magnetic core material particles of the developer carrier used in the present invention include ferrite and magnetite, which are known as two-component carriers for electrophotography, and their metals and zinc, antimony, aluminum, lead, tin and bismuth. Alloys or mixtures with metals such as beryllium, manganese, selenium, tungsten, zirconium and vanadium, and metal oxides such as iron oxide, titanium oxide and magnesium oxide can be used.

The range of resistance as a carrier produced in the present invention is 1.0 × 10 ^{6 to} 3.0 × 10 ¹⁴ Ω.multidot.
cm is suitable, and preferably 3.0 × 10 ^{7 to} 1.0
× 10 ¹⁴ Ω · cm, more preferably 1.0 × 10 ⁸ to
The range is 5.0 × 10 ¹³ Ω · cm.

The developing toner to be mixed with the resin-coated carrier of the present invention is not particularly limited, and any toner that is usually used as an electrophotographic toner can be used without any problem.

Examples of the toner resin include styrene type, acrylic type, styrene / acrylic copolymer type, polyester type and the like. Examples of the internal additives include carbon black, pigments, dyes, magnetic materials and the like as colorants, and charge control agents and release agents as necessary. Depending on the purpose, it may be selected from those having hydrophobicity, alumina, titanium oxide, conductive fine powder, and the like.

FIG. 2 shows an image forming apparatus using the present invention, and the present invention will be further described by using this.

In forming an image, the photosensitive member 10 starts rotating in the clockwise direction, and an electrostatic latent image is formed on the surface of the photosensitive member by the image exposure light from the image exposing means 12. The image information to be written is based on the information provided from a document reading unit (not shown), and the photoconductor is the charger 1.
1 uniformly charges before image exposure.

The electrostatic latent image on the surface of the photoconductor is developed by the developing device 13 to form a toner image. The toner image is transferred by the transfer unit 15 onto the transfer paper (transfer material) supplied from the paper supply unit 17 at the same timing. Separation means 16
The toner image is placed on the transfer sheet peeled off from the photoconductor by the conveying means 19, and the fixing means (fixing device) 2
The toner image is carried to 0, the toner image is fixed, and then the toner image is discharged from the image forming apparatus.

After the transfer paper is separated from the photosensitive member, the toner and the like remaining on the surface of the photosensitive member are removed by the cleaning means 21, and then the process of charging and image exposure is repeated for the next image formation. By repeating this, a large number of images are formed.

The developing device 13 is for developing a latent image formed on the photoconductor 10, and as shown in FIG.
A developer layer carrier (developing sleeve) 133, a blade 134 as a developer spike height regulating member, and the like are included. That is, an opening is formed at a position of the developing device 13 close to the photoconductor 10, and the developer layer carrier 133 is rotatably installed in the opening.
The blades 134 are attached above 3 above with a predetermined gap.

The developer layer carrier 133 is made of a non-magnetic material, rotates in the direction of the arrow in the drawing during the developing operation, and has a magnet 135 as a magnetic field generating means fixed therein. The photoreceptor layer carrier 133 is attached to the photoreceptor 10.
A magnetic field is formed at the position where the developer is applied from, and the magnetic brush is formed at this position.

The developing roller 136 comprises a developer layer carrier 133, a main magnetic pole S ₁ and a magnet 135 having magnetic poles N ₁ , N ₂ , S ₂ and N ₃ for carrying a developer 138, which will be described later. Has been done.

L is a one-dot chain line connecting the center of the developer layer carrier 133 and the center of the photosensitive member 10, and the developer layer carrier 1
The center of opposition between 33 and the photoconductor 10 is shown. In this portion, the developer layer carrying member 133 and the photoconductor 10 are in the closest position and are in the so-called developing area.

Θ is the main magnetic pole S ₁ in the developer layer carrier 133.
Of the main magnetic pole S ₁ and an angle between the center portion of the main magnetic pole and the alternate long and short dash line L. The main magnetic pole S ₁ is indicated as + when it is upstream of the alternate long and short dash line L with respect to the moving direction of the developer layer carrier, and is − when it is downstream.

Θ is in the range of +2 to + 20 °, or −2 to
It is preferably in the range of -20 °. By setting θ within this range, it is possible to reduce the occurrence of carrier adhesion. The blade 134 is aluminum, SUS316
It is made of a non-magnetic material such as, and is attached with a predetermined gap between it and the surface of the developer layer carrier 133 as described above, and this gap allows the developer layer on the developer layer carrier 133 to be attached. Regulate the thickness of 138.

Further, it is desirable that the moving speed (Vs) of the developer layer carrying member is faster than the moving speed (Vp) of the photosensitive member from the viewpoint of complete development, but if the peripheral speed ratio exceeds 3.5. Also in the present invention, carrier scattering and adhesion to the photoconductor are caused. Therefore, as described above, Vs / Vp is preferably 1.5 to 3.5.

The present invention is a copier, laser printer, L
The present invention can be generally applied to electrophotographic image forming apparatuses such as ED printers and liquid crystal shutter type printers, but can also be widely applied to devices such as displays, recording, light printing, plate making, and facsimiles to which electrophotographic technology is applied. It is a thing.

[0093]

By adopting the constitution of the present invention, stable image quality can be maintained for a long period of time even when an organic photoreceptor is used in a high speed machine using a two-component developer.

[0094]

The present invention will be described in detail below with reference to examples, but the embodiments of the present invention are not limited thereto. In the text, “parts” means “parts by weight”.

Example 1 (1) Preparation of Photoreceptor Photoreceptor 1-1 Polyamide resin CM-8000 (manufactured by Toray Industries, Inc.) 30
Parts were put into a mixed solvent of 900 parts of methanol and 100 parts of 1-butanol, and dissolved by heating at 50 ° C. After cooling to room temperature, using this liquid, the outer diameter was 80 mm and the length was 355.5.
An intermediate layer having a thickness of 0.3 μm was formed on the aluminum drum having a thickness of 0.3 mm by dip coating.

Next, 10 parts of polyvinyl butyral resin S-REC BX-1 (manufactured by Sekisui Chemical Co., Ltd.) was dissolved in 1600 parts of methyl ethyl ketone (MEK), and further 30 parts of CGM-1 compound "Chemical Formula 15" below was mixed. rear,
Dispersion was carried out for 20 hours using a sand mill. Using this solution, a charge generation layer having a thickness of 0.3 μm was formed on the above intermediate layer by dip coating.

Subsequently, 500 parts of Exemplified Compound T-2 and Panlite TS-205, a BPZ type polycarbonate resin.
0 (manufactured by Teijin Chemicals Ltd.) 600 parts dichloromethane 3
It was dissolved in 000 parts. Using this solution, a charge transport layer having a thickness of 25 μm was formed on the charge generation layer by dip coating.

Thereafter, the inorganic particles shown in Table 1 below were further added to the charge transport layer solution, and the photoreceptors 1-2 and 1-3 were added.
After being sufficiently dispersed in the first charge transport layer, a second charge transport layer having a thickness of 5 μm was formed on the first charge transport layer by a circular amount regulation type coating machine to prepare photoconductors 1-1, 2 and 3.

Finally, it was heated and dried at 100 ° C. for 1 hour to prepare a photoreceptor in which an intermediate layer, a charge generation layer, a first charge transport layer and a second charge transport layer were sequentially laminated.

[0100]

Embedded image

[0101]

[Table 1]

(2) Developer As a carrier, ferrite particles having a volume average particle diameter of 65 μm are coated with styrene-acrylic resin, and the volume resistance is 10 ¹³ Ω · c.
m carrier was produced.

As the toner, styrene-acrylic resin 1
00 parts, carbon black 6 parts, number average molecular weight 2400
Was mixed with 4 parts of polypropylene, dissolved and kneaded, and then pulverized and classified to obtain colored particles having a volume average particle diameter of 8.4 μm. The one to which 0.8% by weight of hydrophobic silica was added was used.

The above carrier and toner are mixed in a toner concentration of 6%.
To obtain a developer.

(3) Performance Evaluation Using a Konica U-BIX4155 copying machine manufactured by Konica Corporation, the angle of the main magnet is tilted as shown in Table 2 with respect to the line connecting the center of the developer layer carrying member and the photosensitive member to form the photosensitive drum. Table 2
The image evaluation test was conducted 100,000 times in combination as shown in FIG.

Under normal temperature and normal humidity (20 ° C., 60%), a manuscript having a solid black with a reflection density of 1.3, a halftone of 0.3, a white paper part of 0.0 and a resolution chart (A4, coverage of 10%). ) Was used to perform 100,000 times of actual copying tests, and the maximum density and fog were visually evaluated with a reflection densitometer for resolution, unevenness, contrast, etc., and the results are shown in Table 2.

[0107]

[Table 2]

From Table 2, in each of the examples, the maximum density and the fluctuation of the fog are small, and the resolving power characteristics are excellent, but in the comparative example, the density and the fog are decreased due to the abrasion and damage of the photoconductor, or the unevenness due to the poor cleaning is caused. There is, and it turns out that it is poor in practicality.

[0109] Example 2 (1) Preparation Admatechs Co. silica particles "SOC1" inorganic fine particles A ₂ -1~3, "SO
C2 "and titanium oxide particles" A-10 "manufactured by Ishihara Sangyo Kaisha, Ltd.
0 "is treated with a silane coupling agent comprising a trimethylsilyl silane of theory, respectively, to produce a hydrophobic inorganic fine particles A ₂ -1, A ₂ -2 and A ₂ -3.

(2) Preparation of Photoreceptor Photoreceptor 2-1 1.5 parts of polyamide resin CM-8000 (manufactured by Toray Industries, Inc.) was placed in a mixed solvent of 90 parts of methanol and 10 parts of 1-butanol and heated at 50 ° C. Dissolved. After cooling to room temperature, this solution was used for dip coating to a thickness of 0.3 μm on an aluminum drum having an outer diameter of 80 mm and a length of 355.5 mm.
Was formed.

Next, 0.8 part of polyvinyl butyral resin S-REC BX-1 (manufactured by Sekisui Chemical Co., Ltd.) was dissolved in 80 parts of methyl ethyl ketone (MEK) and 20 parts of cyclohexane, and further 4 parts of the following "Chemical Formula 15" compound CGM-1. After mixing, the mixture was dispersed for 20 hours using a sand mill. Using this solution, a charge generation layer having a thickness of 0.2 μm was formed on the above intermediate layer by dip coating.

Then, 10 parts of Exemplified Compound T-31 and BPZ type polycarbonate resin "UPILON Z300" were used.
15 parts (manufactured by Mitsubishi Gas Chemical Co., Inc.) and 0.25 parts of a hindered phenolic antioxidant were dissolved in 100 parts of methylene chloride. Using this solution, a charge transport layer having a thickness of 20 μm was formed on the charge generation layer by dip coating.

Then, 1 part of the exemplified compound T-31 and B were used.
PZ type polycarbonate resin "Iupilon Z300"
1.5 parts (manufactured by Mitsubishi Gas Chemical Co., Inc.) and 0.025 parts of a hindered phenolic antioxidant, the hydrophobic inorganic fine particles A.
₂ -1 were added 0.6 parts were dispersed and dissolved in methylene chloride 20 parts. Using this solution, a second charge transport layer having a thickness of 5 μm was formed on the first charge transport layer by a circular amount regulation type coating machine to obtain a photoconductor 2-1.

Similarly, the hydrophobic inorganic fine particles A ₂ -2 and A _2-
3 was added to prepare photoconductors 2-2 and 2-3.
Inorganic particles were not added to the photoconductor 2-4.

Finally, it was heated and dried at 100 ° C. for 1 hour to obtain a photoreceptor in which an intermediate layer, a charge generation layer, a first charge transport layer and a second charge transport layer were sequentially laminated.

(3) Developer As a carrier, ferrite and iron particles having a volume average particle diameter of 80 μm were coated with a fluorine resin to prepare five kinds of carriers shown in Table 3 below.

[0117]

[Table 3]

As the toner, styrene-acrylic resin 1
00 parts, carbon black 6 parts, number average molecular weight 2400
Was mixed with 4 parts of polypropylene, dissolved and kneaded, and then pulverized and classified to obtain colored particles having a volume average particle diameter of 8.4 μm. The one to which 0.8% by weight of hydrophobic silica was added was used.

96 parts of the above carrier and 4 parts of toner were mixed so as to have a toner concentration of 6% to obtain 5 kinds of developers.

(4) Performance Evaluation A Konica U-BIX4145 copier (photoconductor drum diameter 80 mm, peripheral speed 270 mm) manufactured by Konica Corporation was improved, and the developer layer carrier and the photoconductor drum were rotated under the conditions shown in Table 4 below. The image evaluation test was performed 100,000 times in combination.

Under normal temperature and normal humidity (20 ° C., 60%), a document having a solid black with a reflection density of 1.3, a halftone of 0.3, a white paper part of 0.0 and a resolution chart (A4, coverage of 10%). ) Was used to perform 100,000 times of actual copying tests, and maximum density and fog were visually evaluated with a reflection densitometer for resolution, unevenness, contrast, etc., and the results are shown in Table 4.

[0122]

[Table 4]

From Table 4, in each of the examples, the maximum density and the fluctuation of the fog are small, and the resolving power characteristics are excellent, but in the comparative example, the density and the fog are decreased due to the abrasion and damage of the photoconductor, or the unevenness due to the poor cleaning is caused. There is, and it turns out that it is poor in practicality.

[0124]

According to the present invention, there is provided an image forming method capable of stably obtaining a high image quality for a long period of time, even when the image is repeatedly formed by a two-component developer method, without causing abrasion and damage of the photosensitive member and deterioration due to ozone. Can be provided.

[Brief description of drawings]

FIG. 1 is a sectional view showing a layer structure of a photoreceptor according to the present invention.

FIG. 2 is a configuration cross-sectional view showing an example of an image forming apparatus using the present invention.

FIG. 3 is a cross-sectional view illustrating a positional relationship between a photoconductor according to the present invention, a developer layer carrier, and a main magnet.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Conductive support 2 Intermediate layer 3 Charge transport layer (CTL) 4 Charge generation layer (CGL) 5 Protective layer 6 Photosensitive layer 10 Photoreceptor 11 Charging means Charging device 13 Developing means Developing device 15 Transfer means Transfer device 20 Fixing device which is a fixing device 21 Cleaning device which is a cleaning device 133 Developer layer carrying member L A line connecting both centers of the photoconductor and the developer layer carrying member S ₁ Main magnet

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G03G 9/113 G03G 15/08 507X 15/08 501 9/10 311 507 351

Claims (8)

[Claims] 1. An image forming method for developing an electrostatic latent image on an organic photoconductor with a two-component developer, wherein the outermost surface layer of the organic photoconductor contains inorganic fine particles, and the main component in the developer layer-carrying body is contained. An image forming method characterized in that the center of the magnetic pole is tilted by 2 to 20 ° with respect to the line connecting the center of the developer layer carrier and the center of the photoreceptor. 2. The organic photoreceptor has a charge generation layer on a conductive support and a plurality of charge transport layers laminated thereon,
2. The outermost surface layer is a charge transport layer.
The image forming method as described in the above. 3. The image forming method according to claim 1, wherein the inorganic fine particles have a Mohs hardness of 5 or more and a volume average particle diameter of 0.05 to 2.0 μm. 4. The scratch depth when a vertical load of 200 g is applied by using a diamond needle having a photosensitive layer film strength of the organic photoreceptor of 0.3 mm in tip radius is 0.1 to 1.0 μm. The image forming method according to claim 1, 2, or 3. 5. An image forming method for developing an electrostatic latent image on an organic photoconductor with a two-component developer, wherein the outermost surface layer of the organic photoconductor contains inorganic fine particles, and the carrier of the two-component developer is It is a resin coating carrier of ferrite or magnetite, and the moving speed (Vs) of the developer layer carrier is 1
An image forming method, wherein the ratio (Vs / Vp) to the moving speed (Vp) of the photoconductor is 1.5 to 3.5 at 50 mm / sec or more. 6. The organic photoreceptor has a charge generation layer on a conductive support and a plurality of charge transport layers laminated thereon,
The outermost surface layer is a charge transport layer, and
The image forming method as described in the above. 7. The image forming method according to claim 5, wherein the inorganic fine particles have a Mohs hardness of 5 or more and a volume average particle diameter of 0.05 to 2.0 μm. 8. The scratch depth of 0.1 to 1.0 μm when a vertical load of 200 g is applied by using a diamond needle having a photosensitive layer film strength of the organic photoreceptor of 0.3 mm in tip radius. The image forming method according to claim 5, 6, or 7.