JP2003215836A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To use toner that has high average circularity and a small particle diameter in order to obtain an image of high image quality, to decrease electrostatic adhesion force between the surface of an electrophotographic photoreceptor and toner, to ensure sufficient cleaning, to decrease load on an elastic rubber blade used for cleaning, and to prevent toner from slipping from the blade or forming a film on the photoreceptor. <P>SOLUTION: The image forming device forms a multicolor image by using the electrophotographic photoreceptor used for image formation repeatedly and a plurality of developing units, each of which contains color toner with an average circularity of 0.95 to 0.99 and uses the elastic rubber blade in order to clean the photoreceptor. In the image forming device, at least one or more of the toners of different colors contain silica particles as an addition agent and inorganic fine particles with a wt. average particle diameter (D50) of 100 to 1000 nm. <P>COPYRIGHT: (C)2003,JPO

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 apparatus for forming a color image used as a copying machine, a printer or the like.

[0002]

2. Description of the Related Art In recent years, an image forming apparatus is required to output a high quality image, and in order to meet the demand, a technique using a small particle diameter toner has been proposed.

[0003] For example, Japanese Patent Laid-Open No. 2000-81722 discloses that fine line reproducibility and gradation are extremely good, and high image quality comparable to that of offset printing can be obtained without giving a visually uncomfortable feeling. It is described that the cleaning property can be improved. In addition, at least 4 of cyan, magenta, yellow, and black are formed on the transfer material.
Even in the color image forming method of forming a full-color image by superposing color toner images, if the above-mentioned electrostatic latent image developing toners are used for the four color toners, the reproducibility of fine lines and the image on the transfer material can be improved. Is improved, the image thickness is further reduced, and an extremely high-quality color image can be formed.

On the other hand, as a cleaning means, cleaning using an elastic rubber blade (cleaning blade) is widely used because of its simple structure and durability. However, if images are repeatedly formed for a long period of time, the edge of the elastic rubber blade is worn or missing due to friction with the surface of the electrophotographic photosensitive member (sometimes simply referred to as photosensitive member) or the toner, and the toner becomes elastic. Poor cleaning that slips through the rubber blade may occur.

This phenomenon is more likely to occur as the toner particle size is reduced, and especially under low temperature and low humidity environment conditions or when the amount of toner to be cleaned is large, for example, toner image for toner density control and gradation correction. When cleaning is carried out after the toner is formed on the surface of the photoconductor and is transferred onto the photoconductor or the intermediate transfer member, cleaning failure is likely to occur.

In particular, the particle size of the toner is reduced and
Spherical polymerization toner has a strong tendency to do so, and color toners often use organic pigments as colorants, which increases the resistance of the toner, resulting in a large electrostatic adhesion to the surface of the photoconductor. However, it is more difficult to scrape off with an elastic blade than black toner.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is to reduce the electrostatic adhesive force between the electrophotographic photosensitive member surface and the toner on the assumption that a small particle size toner having a high average circularity is used to obtain a high quality image. Lowering and sufficient cleaning, even when the load on the elastic rubber blade for cleaning is reduced, the occurrence of toner slipping through the blade and filming on the photoconductor are eliminated. An object is to provide an image forming apparatus that ensures durability.

[0008]

Means for Solving the Problems As a result of intensive studies by the inventors, it was found that the object of the present invention can be achieved by adopting any of the following constitutions.

[1] An electrophotographic photosensitive member used for repeated image formation, and each having an average circularity of 0.95 to 0.9.
In an image forming apparatus that forms a multicolor image by using a plurality of developing devices loaded with color toners of No. 9 and uses an elastic rubber blade for cleaning the photoconductor, at least one color toner is used. , Silica-based particles as an external additive, and a weight average particle diameter (D50) of 100 to 1000 n
An image forming apparatus, wherein m inorganic fine particles are added.

[2] The image forming apparatus according to [1], wherein the toner to which the inorganic fine particles are added is any one of yellow, magenta, and cyan toners.

[3] The image forming apparatus according to [1], wherein the inorganic fine particles are barium sulfate coated with tin oxide.

[4] The image forming apparatus according to [1], wherein the inorganic fine particles have a BET specific surface area of 10 to 30 m ² / g.

[5] Each of the color toners has a volume average particle size of 3 to 8 μm [1]
The image forming apparatus described.

[6] The image forming apparatus according to [1], wherein each of the color toners is produced by a polymerization method.

In the present invention, the electrophotographic photosensitive member on which an image is repeatedly formed is obtained by developing a latent image formed on the photosensitive member into a toner image, transferring the toner image to an image support and then fixing it to obtain a finished image. Refers to the photoconductor used in the method.
After transferring the toner image, the photosensitive member is cleaned and reused repeatedly. Therefore, the photosensitive member is required to have stable mechanical properties such as potential characteristics upon repeated use and mechanical strength such that the surface is not scratched. On the other hand, for the image forming process, it is necessary to adopt a method that does not damage the potential characteristics and surface properties of the photoconductor.

Further, the average circularity of the toner means an average value of circularity = (perimeter of circle determined from equivalent circle diameter) / (perimeter of projected image of particle).

The method of measuring the circularity is not limited, but, for example, a photograph obtained by magnifying toner particles by a magnification of 500 with an electron microscope is taken, and an image analyzer is used to measure 500.
The average circularity can be calculated by measuring the circularity of each toner and obtaining the arithmetic mean value thereof. Further, as a simple measuring method, FPIA-1000 (manufactured by Toa Medical Electronics Co., Ltd.) can be used for measurement.

In order to control this shape, an appropriate process end time may be determined while monitoring the characteristics of the toner particles (colored particles) whose shape is being controlled by a process such as association.

When the average circularity of the toner is less than 0.95, it means that a large amount of flat toner and toner particles having many irregularities on the surface are contained, and the charging characteristics, the transfer characteristics, and the like are greatly varied, and the image is The characteristics and the like also tend to change. However, if it exceeds 0.99, it is difficult to make, and even if it is obtained, the image characteristics and the like are not improved so much, so there is little industrial meaning to make the thing exceeding 0.99.

The volume average particle size of the toner of the present invention is measured by Coulter Counter TA-II or Coulter Multisizer (manufactured by Coulter Co.). In the present invention, a Coulter Multisizer was used, and an interface (manufactured by Nikkaki Co., Ltd.) for outputting a particle size distribution and a personal computer were connected and used. The aperture used in the Coulter Multisizer was 100 μm, and the volume distribution of the toner of 2 μm or more was measured to calculate the particle size distribution and the average particle size.

The particle size of the toner of the present invention is preferably 3-8 μm in volume average particle size. When the toner particles are formed by a polymerization method, this particle size is the aggregating agent (associating agent,
Concentration of salting-out agent), amount of organic solvent added, or fusion time,
Furthermore, it can be controlled by the composition of the polymer itself. In the polymerization method, both the average circularity and the particle size of the above toner are
Although the adjustment can be performed relatively easily, the adjustment is more difficult by the pulverization method, and in that sense, the polymerization method is preferable for producing the toner of the present invention.

The weight average particle size of the inorganic fine particles according to the present invention can be measured by using an electrophoretic light scattering photometer "ELS-800" (manufactured by Otsuka Electronics Co., Ltd.).

As shown in FIG. 1 as an example of a sectional view of the cleaning means (apparatus) 8, the elastic rubber blade used in the present invention is constructed so as to have a free end on the support member 227. is there. As the material of the elastic rubber blade, urethane rubber, silicone rubber or the like is used, but any material may be used without particular limitation as long as the above physical properties are satisfied.

The free end of the elastic rubber blade 221 is preferably in pressure contact with the opposite side (counter) to the rotation direction of the photosensitive member 1.

In the present invention, the elastic rubber blade has a rubber hardness of JIS A 60 to 70 ° and a impact resilience of 30 to.
70%, free length 7 to 12 mm, pressing force on the photoconductor is 5
It is preferable to use one having a viscosity of -30 mN / cm. Also,
Young's modulus is 3000-6000 kPa, thickness is 1.5-
It is preferably 3.0 mm, but is not particularly limited.

Although silica-based particles are often added as an external additive to toners used today, the addition of silica-based particles is also essential in the present invention, and in addition, in the present invention. Weight average particle diameter (D50) is 10
Inorganic fine particles of 0 to 1000 nm are added. It is considered that this particle size is appropriate for effectively adhering to the toner surface and ensuring the fluidity and conductivity of the toner to some extent.

Examples of the inorganic fine particles include barium sulfate, strontium titanate, aluminum titanate,
There are tungsten oxide, tin oxide, titanium nitride, and silica, and barium sulfate is preferable among them. Further, it is more preferable that the surface of the particles is coated with tin oxide.

The addition amount is preferably 0.5 to 5.0 mass% with respect to the colored particles (toner). The shape of the inorganic fine particles is preferably such that the BET specific surface area determined by the BET method is 10 to 30 m ² / g.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION The compound, toner, image forming apparatus and the like used in the present invention will be further described.

Method of Producing Toner The toner of the present invention is not particularly limited, but it has already been described that a polymerization method using a so-called emulsion polymerization method or suspension polymerization method is preferable to a usual pulverization method.

That is, in the production of a toner using the suspension polymerization method, various constituent materials such as a colorant and, if necessary, a release agent, a charge control agent, and a polymerization initiator are added to the polymerizable monomer. Then, various constituent materials are dissolved or dispersed in the polymerizable monomer by using a homogenizer, a sand mill, a sand grinder, an ultrasonic disperser or the like. The polymerizable monomer in which these various constituent materials are dissolved or dispersed is dispersed in an oil droplet having a desired size as a toner in a water-based medium containing a dispersion stabilizer by using a homomixer or a homogenizer. Then, the mixture is transferred to a reactor equipped with a stirring mechanism and heated to allow the polymerization reaction to proceed. After the reaction is complete, the dispersion stabilizer is removed, filtered, washed, and dried to prepare the colored particles used in the present invention.

A toner obtained by adding an external additive to the colored particles is called a toner. If no misunderstanding occurs in the present invention,
Colored particles may also be referred to as toner.

As a method for producing the toner of the present invention, a method of preparing resin particles by emulsion polymerization and then associating or fusing them in an aqueous medium can be preferably used. This method is not particularly limited, but for example, the methods described in JP-A-5-265252, JP-A-6-329947, and JP-A-9-15904 can be mentioned. That is, a method of associating a plurality of resin particles and dispersed particles of a constituent material such as a colorant, or a plurality of fine particles composed of a resin and a colorant, in particular, after dispersing these in water with an emulsifier, the critical aggregation concentration At the same time as the above coagulant is added and salted out, the particle size is gradually grown while forming a fused particle by heating and fusing at a temperature not lower than the glass transition temperature of the resin. Add a large amount to stop grain size growth,
The toner of the present invention can be formed by further smoothing the surface of the particles while heating and stirring to control the shape and heating and drying the particles in a fluid state in a fluid state. Here, an organic solvent that is infinitely soluble in water may be added simultaneously with the coagulant.

The polymerizable monomers used for the toner resin of the present invention include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene and α-.
Methylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn- Styrene or styrene derivative such as octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, methacryl Isobutyl acid, methacrylic acid t
-Butyl, n-octyl methacrylate, methacrylic acid 2
-Methacrylic ester derivatives such as ethylhexyl, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, T-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-acrylate
Ethylhexyl, stearyl acrylate, lauryl acrylate, phenyl acrylate, acrylic ester derivatives, olefins such as ethylene, propylene and isobutylene, vinyl chloride, vinylidene chloride, vinyl bromide,
Halogen vinyls such as vinyl fluoride and vinylidene fluoride, vinyl propionate, vinyl acetate, vinyl esters such as vinyl benzoate, vinyl ethers such as vinyl methyl ether and vinyl ethyl ether, vinyl methyl ketone, vinyl ethyl ketone, Vinyl ketones such as vinyl hexyl ketone, N-vinyl compounds such as N-vinyl carbazole, N-vinyl indole and N-vinyl pyrrolidone, vinyl compounds such as vinyl naphthalene and vinyl pyridine, acrylics such as acrylonitrile, methacrylonitrile and acrylamide. There are acid or methacrylic acid derivatives. These vinyl monomers can be used alone or in combination.

Further, it is more preferable to use a combination of those having an ionic dissociative group as the polymerizable monomer constituting the resin. For example, those having a substituent such as a carboxyl group, a sulfonic acid group and a phosphoric acid group as a constituent group of the monomer, and specifically, acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumar Acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester, styrenesulfonic acid, allylsulfosuccinic acid, 2-acrylamido-2-methylpropanesulfonic acid, acid phosphooxyethyl methacrylate, 3
-Chloro-2-acid phosphooxypropyl methacrylate and the like can be mentioned.

Further, divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate,
It is also possible to use a polyfunctional vinyl such as neopentyl glycol diacrylate to form a resin having a crosslinked structure.

These polymerizable monomers can be polymerized using a radical polymerization initiator. In this case, an oil-soluble polymerization initiator can be used in the suspension polymerization method.

The resin excellent in the present invention preferably has a glass transition point of 20 to 90 ° C. and a softening point of 8
It is preferably 0 to 220 ° C. The glass transition point is measured by a differential calorimetric method, and the softening point can be measured by a Koka type flow tester. Furthermore, these resins have a number average molecular weight (Mn) of 10 as measured by gel permeation chromatography.
00-100,000, 200 in weight average molecular weight (Mw)
It is preferably 0 to 1,000,000. Furthermore, as the molecular weight distribution, Mw / Mn is 1.5 to 100, and particularly 1.8.
The thing of -70 is preferable.

The toner of the present invention contains at least a resin and a colorant, but may contain a fixing property improving agent (release agent), a charge control agent and the like, if necessary.

As the colorant used in the toner of the present invention, carbon black, magnetic materials, dyes, pigments and the like can be optionally used. Examples of the carbon black include channel black, furnace black, acetylene black,
Thermal black, lamp black, etc. are used. Ferromagnetic metals such as iron, nickel, and cobalt as magnetic materials,
Alloys containing these metals, compounds of ferromagnetic metals such as ferrite and magnetite, alloys containing no ferromagnetic metals but exhibiting ferromagnetism by heat treatment, such as manganese-copper-
Aluminum, manganese-copper-tin, and other types of alloys called Heusler alloys, chromium dioxide, and the like can be used.

As the dye, C.I. I. Solvent Red 1, 49, 52, 58, 63, 111, 1
22, C.I. I. Solvent Yellow 19, 44, 7
7, ibid 79, ibid 81, ibid 82, ibid 93, ibid 98, ibid 10
3, 104, 112, 162, C.I. I. Solvent Blue 25, 36, 60, 70, 93, 9
5 and the like can be used, and a mixture thereof can also be used. As the pigment, C.I. I. Pigment Red 5, Same 48: 1, Same 53: 1, Same 57: 1, Same 122,
139, 144, 149, 166, 177,
178, 222, C.I. I. Pigment Orange 3
1, 43, C.I. I. Pigment Yellow 14 and 1
7, ibid 93, ibid 94, ibid 138, C.I. I. Pigment Green 7, C.I. I. Pigment Blue 15: 3, 60
Etc. can be used, and a mixture thereof can also be used. The number average primary particle size varies depending on the type,
About 10 to 200 nm is preferable.

Further, low molecular weight polypropylene (number average molecular weight = 1500 to 9) as a fixing property improving agent (release agent).
000) or low molecular weight polyethylene may be added.

Similarly, the charge control agents are various known ones,
Moreover, the thing which can be disperse | distributed in water can be used. Specifically, nigrosine dyes, metal salts of naphthenic acid or higher fatty acids, alkoxylated amines,
Examples thereof include secondary ammonium salt compounds, azo-based metal complexes, salicylic acid metal salts or metal complexes thereof.

The particles of these charge control agents and fixability improvers have a number average primary particle diameter of 10 to 500 in a dispersed state.
It is preferably about nm.

External Additive In the toner of the present invention, the effect can be more enhanced by using the above-mentioned inorganic fine particles as an external additive in addition to the silica-based external additive. The reason for this is that the embedding and detachment of the external additive can be effectively suppressed,
It is estimated that the effect is remarkable.

The commonly used silica-based external additive may contain, in addition to silica, inorganic oxide particles such as titania and alumina. Further, these particles include silane coupling agents and titanium coupling agents. It is preferably subjected to a hydrophobic treatment by.

The silane-based external additive has a number average primary particle size of 0.0
The addition amount is preferably 0.5 to 5.0 parts by mass, and more preferably 0.5 to 4.0 parts by mass with respect to 100 parts by mass of the toner particles.

Photosensitive Member The photosensitive member used in the present invention is preferably an organic photosensitive member. This is because the effect of the present invention is more remarkably exhibited.

The structure of the organic photoconductor is usually constituted by coating an undercoat layer (intermediate layer) on the surface of a drum-shaped photoconductor substrate, if necessary, and laminating a charge generation layer and a charge transport layer thereon. In many cases, a surface protective layer is further coated on it.

That is, the layer structure of the organic photoconductor of the present invention is not particularly limited, but a charge generation layer, a charge transport layer, or a charge generation / charge transport layer (having a function of both charge generation and charge transport). It is preferable to adopt a constitution in which a photosensitive layer such as a layer type photosensitive layer) and a resin layer are coated thereon. Further, each of the charge generation layer, the charge transport layer, or the charge generation / charge transport layer may be composed of a plurality of layers.

Examples of the charge generating substance (CGM) contained in the charge generating layer of the present invention include phthalocyanine pigments and
Polycyclic quinone pigments, azo pigments, perylene pigments, indigo pigments, quinacridone pigments, azurenium pigments, squarylium dyes, cyanine dyes, pyrylium dyes, thiopyrylium dyes, xanthene dyes, triphenylmethane dyes,
Examples of the charge-generating substance (C
GM) is used alone or together with a suitable binder resin to form a layer.

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

Charge generation layer (CGL), charge transport layer (CT
Examples of the binder resin contained in L) include polycarbonate resin, polyester resin, polystyrene resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride 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 can be mentioned.

In the present invention, the ratio of the charge generating substance to the binder resin in the charge generating layer is 1:10 to 1 in mass ratio.
0: 1 is preferred. The thickness of the charge generation layer is preferably 5 μm or less, and particularly preferably 0.05 to 2 μm.

The charge transport layer is formed by dissolving the above charge transport material and the binder resin in a suitable 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 in mass ratio.

The thickness of the charge transport layer is usually 5 to 50 μm, particularly preferably 10 to 40 μm. When a plurality of charge transport layers are provided, the thickness of the upper layer of the charge transport layer is 10
The thickness is preferably not more than μm, and is preferably smaller than the total thickness of the charge transport layer provided below the charge transport layer.

In the present invention, it is preferable to provide an intermediate layer (undercoat layer) having a barrier function between the conductive support (conductive substrate) and the photosensitive layer.

Materials for the intermediate layer include casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyvinyl butyral, phenol resin polyamides (nylon 6, nylon 66, nylon 610, copolymer nylon, alkoxymethyl). Nylon chloride, etc.), polyurethane, gelatin and aluminum oxide, or a curable intermediate layer using a metal alkoxide, an organic metal chelate, or a silane coupling agent as described in JP-A-9-68870. The thickness of the intermediate layer is preferably 0.1 to 10 μm, particularly 0.1 to 10 μm.
5 μm is preferable.

Next, as the conductive support of the photoreceptor used in the present invention, 1) a metal plate such as an aluminum plate or a stainless plate, 2) a support such as paper or a plastic film,
A thin metal layer such as aluminum, palladium, or gold provided by lamination or vapor deposition 3) On a support such as paper or plastic film,
Examples thereof include those in which a layer of a conductive compound such as a conductive polymer, indium oxide, or tin oxide is provided by coating or vapor deposition.

Materials for the conductive support used in the present invention are mainly aluminum, copper, brass, steel,
A metal material such as stainless steel or other plastic material molded into a belt shape or a drum shape is used. Among them, aluminum, which is excellent in cost and workability, is preferably used, and a thin-walled cylindrical aluminum element tube that is usually extruded or pultruded is often used.

Further, the conductive support may have a surface on which a sealed alumite film is formed.

Next, as a coating processing method for producing the photosensitive member used in the present invention, coating processing methods such as dip coating, spray coating and circular amount regulation type coating are used.
The coating process on the resin layer side uses a coating process method such as spray coating or circular amount regulation type (a circular slide hopper type is a typical example) coating in order to not dissolve the lower layer film as much as possible and to achieve uniform coating process. Is preferred. The spray coating is described in detail in, for example, JP-A-3-90250 and JP-A-3-269238, and the circular amount regulation coating is described in JP-A-58-18.
This is described in detail in Japanese Patent Publication No. 9061.

Image Forming Apparatus Next, although not limited to this, an image forming process of a digital copying machine adopting the image forming method according to the present invention will be described with reference to FIG.

The image forming process of the present invention may be a one-component developing method or a two-component developing method, but it is particularly effective in an image forming method including reversal development of a digital copying machine or the like.

FIG. 2 is a sectional view for explaining the structure of a color copying machine, which is an example of an image forming apparatus having an intermediate transfer member according to the present invention. Used for forming color images in multiple colors.

The image forming apparatus main body GH shown in FIG. 2 is called a tandem type color image forming apparatus, and includes a plurality of sets of image forming sections 10Y (yellow), 10M (magenta), 10C (cyan), 10K (black). ), A belt-shaped intermediate transfer member 6, a sheet feeding / conveying unit, and a fixing device 24.

Image forming section 1 for forming a yellow image
0Y has a charging unit 2Y, an exposing unit 3Y, a developing unit 4Y, a transfer unit 7Y, and a cleaning unit 8Y, which are arranged around a photoconductor 1Y as an image forming body. The image forming unit 10M that forms a magenta image has a photoreceptor 1M as an image forming body, a charging unit 2M, an exposing unit 3M, a developing unit 4M, and a cleaning unit 8M. The image forming unit 10C that forms a cyan image includes a photoconductor 1C as an image forming body, a charging unit 2C, an exposing unit 3C, and a developing unit 4.
C, and a cleaning means 8C. The image forming unit 10K that forms a black image includes a photoreceptor 1 as an image forming body.
K, charging means 2K, exposure means 3K, developing means 4K, and cleaning means 8K. The charging unit 2Y and the exposure unit 3Y, the charging unit 2M and the exposure unit 3M, the charging unit 2C and the exposure unit 3C, and the charging unit 2K and the exposure unit 3K form a latent image forming unit.

The intermediate transfer member 6 is an endless belt,
It is stretched by a plurality of rollers and is rotatably supported.

Image forming units 10Y, 10M, 10C and 1
The color image of each color formed from 0K is transferred onto the rotating intermediate transfer member 6 by transfer means (primary transfer means) 7Y, 7M, 7
Sequential transfer by C and 7K forms a superimposed color image.

The image support P housed in the paper feed cassette 20 is fed by the paper feed means 21 and fed by the paper feed roller 22.
After passing through A, 22B and 22C, the registration roller 23 and the like, the image is conveyed to the transfer unit (secondary transfer unit) 7A and the image support P
The superimposed color image is transferred on top. The image support P on which the color image is transferred is fixed by the fixing device 24, sandwiched by the paper discharge rollers 25, and placed on the paper discharge tray 26 outside the machine.

On the other hand, after the color image is transferred onto the image support P by the transfer means 7A, the residual toner on the intermediate transfer body 6 from which the image support P is separated is removed by the cleaning means 8A.

The toner patch density detection sensor 13
Image forming units 10Y, 10M, 10C and 10 of the copying machine
The toner patch formed by K is detected. This patch is not formed as a final image, and when the intermediate transfer body on which these patches are formed passes through the transfer means 7A (secondary transfer means) portion, the transfer means 7A is released and the image is supported. After the toner reaches the density detection sensor 13 without being transferred to the body and the detection is completed, the cleaning unit 8A removes the residual toner.

In the above description, the transfer means (primary transfer means) 7Y, 7M, 7C and 7K is not limited by its mechanism, but is an elastic roller type in which an elastic body is mounted on a cored bar such as a metal rod. It is preferable to apply a voltage to the above.

Incidentally, 5Y, 5M, 5C and 5K are toner replenishing means for replenishing the developing means 4Y, 4M, 4C and 4K with new toner.

An image reading device YS including an automatic document feeder 201 and a document image scanning exposure device 202 is installed above the image forming apparatus main body GH. The original d placed on the original table of the automatic original feeding device 201 is conveyed by the conveying means, and the image of one side or both sides of the original is scanned and exposed by the optical system of the original image scanning exposure device 202, and the line image sensor CCD is exposed. Is read.

The analog signal photoelectrically converted by the line image sensor CCD is subjected to analog processing, A / D conversion, shading correction, image compression processing, etc. in the image processing section, and then the image writing section (exposure means) 3Y, Three
Send signals to M, 3C and 3K.

The automatic document feeder 201 is provided with an automatic double-sided document conveying means. Since the automatic document feeder 201 can continuously read the contents of a large number of documents d fed from the document table and store them in the storage means (electronic RDH function), copying is possible. It is conveniently used when copying the contents of a large number of originals by the function or when transmitting a large number of originals d by the facsimile function.

Of course, the present invention is different from the configuration of FIG. 2 in that the signal for each separated color which is color-separated at the time of image reading is developed by charging, image writing by laser light exposure and corresponding color toner. Repeat the process, 4 for yellow, magenta, cyan and black toner
A color toner image may be formed on the photoconductor and transferred to the transfer material at once.

Other Structures A suitable fixing method used in the present invention is a so-called contact heating method. In particular, as the contact heating method, a heat pressure fixing method, a heat roller fixing method, and a pressure contact heating fixing method in which fixing is performed by a rotating pressure member containing a fixedly arranged heating body can be mentioned.

The image forming apparatus of the present invention can be applied to general electrophotographic apparatuses such as copying machines, laser printers, LED printers and liquid crystal shutter printers. It can be widely applied to devices such as light printing, plate making, and facsimile.

Furthermore, in addition to the above, the image information is previously RO
The image can be stored in an image memory such as M or a magnetic disk, and the information in the image memory can be taken out as necessary and output to the image forming unit. Therefore, an apparatus that does not have an image reading unit but stores information from a computer or the like in a memory and outputs the information to the image forming unit is also included in the image forming apparatus of the present invention. The most common of these are LED printers and LBPs (laser beam printers).

[0082]

EXAMPLES Next, the structure and effects of the present invention will be specifically described with reference to examples, but the structure of the present invention is not limited to these.

Example 1 1. Preparation of toner and developer [latex 1HML] (1) Preparation of core particles (first-stage polymerization) An anionic surfactant (5000 ml separable flask equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introducing device) _{101) C 10 H 21 (OCH} 2 CH 2) 2 OSO 3 Na
A surfactant solution (aqueous medium) in which 7.08 g was dissolved in 3010 g of ion-exchanged water was charged, and the temperature inside the flask was raised to 80 ° C. while stirring at a stirring rate of 230 rpm under a nitrogen stream.

To this surfactant solution, 9.2 g of a polymerization initiator (potassium persulfate: KPS) was added 200 g of ion-exchanged water.
Was added to the solution of the initiator, and the temperature was adjusted to 75 ° C. Then, 70.1 g of styrene and 1 of n-butyl acrylate were added.
A monomer mixture liquid consisting of 9.9 g and methacrylic acid 10.9 g was added dropwise over 1 hour, and this system was heated and stirred at 75 ° C. for 2 hours to perform polymerization (first-stage polymerization), A latex (dispersion of resin particles composed of a high molecular weight resin) was prepared. This is designated as "latex (1H)".

(2) Formation of Intermediate Layer (Second Stage Polymerization) In a flask equipped with a stirrer, styrene 1
A monomer mixture liquid consisting of 05.6 g, 30.0 g of n-butyl acrylate, 6.2 g of methacrylic acid and 5.6 g of n-octyl-3-mercaptopropionic acid ester was added to 90
A monomer solution was prepared by heating at 0 ° C. and dissolving.

On the other hand, the anionic surfactant (the above formula (1
01)) 1.6 g of ion-exchanged water dissolved in 2700 ml of a surfactant solution was heated to 98 ° C., and the latex solution (1H) as a dispersion of core particles was added to the surfactant solution.
After adding 28 g of solid content, a mechanical dispersion machine with a circulation path "CLEARMIX"
A dispersion liquid (emulsion liquid) containing emulsified particles (oil droplets) was prepared by (M-Technique Co., Ltd.).

Next, to this dispersion (emulsion), an initiator solution prepared by dissolving 5.1 g of a polymerization initiator (KPS) in 240 ml of ion-exchanged water and 750 ml of ion-exchanged water were added, and this system was added to 98 Polymerization (second-stage polymerization) is performed by heating and stirring at ℃ for 12 hours to obtain latex (dispersion liquid of composite resin particles having a structure in which the surface of resin particles made of high molecular weight resin is coated with intermediate molecular weight resin). Obtained. This is designated as "latex (1HM)".

(3) Formation of outer layer (third stage polymerization) An initiator solution prepared by dissolving 7.4 g of a polymerization initiator (KPS) in 200 ml of deionized water in the latex (1HM) obtained as described above. Was added, and under the temperature condition of 80 ° C., 300 g of styrene and 95% of n-butyl acrylate were added.
g, 15.3 g of methacrylic acid, and 10.4 g of n-octyl-3-mercaptopropionic acid ester were added dropwise over 1 hour. After completion of the dropping, polymerization (third stage polymerization) was carried out by heating and stirring for 2 hours, followed by cooling to 28 ° C. and latex (a central part made of a high molecular weight resin, an intermediate layer made of an intermediate molecular weight resin, and a low layer). A dispersion liquid of composite resin particles having an outer layer made of a molecular weight resin was obtained.

This latex is referred to as "latex (1HM
L) ”. The composite resin particles constituting this latex (1HML) had peak molecular weights of 138,000, 80,000 and 13,000, and the weight average particle diameter of the composite resin particles was 122 nm.

[Latex 2HML] Surfactant (10
In the same manner as latex (1HML), except that anionic surfactant (sodium dodecylbenzene sulfonate: SDS) 7.08 g was used instead of 1), a latex (a central part made of a high molecular weight resin, A dispersion liquid of composite resin particles having an intermediate layer made of an intermediate molecular weight resin and an outer layer made of a low molecular weight resin was obtained. This latex is referred to as "latex (2HML)".

The composite resin particles constituting this latex (2HML) are 138,000, 80,000 and 1
It has a peak molecular weight of 2,000, and
The weight average particle diameter of the composite resin particles was 110 nm.

[Production of Colored Particles] 59.0 g of anionic surfactant (101) was dissolved in 1600 ml of ion-exchanged water with stirring, and while stirring this solution, 420.0 g of quinacridone-based magenta pigment was gradually added. Then, a dispersion of colorant particles (hereinafter referred to as "colorant dispersion 1") was prepared by performing a dispersion treatment using "CLEARMIX" (manufactured by M-Technique Co., Ltd.). The particle size of the colorant particles in this colorant dispersion was measured using an electrophoretic light scattering photometer "ELS-800" (manufactured by Otsuka Electronics Co., Ltd.), and the weight average particle size was 89 nm.

Latex 1 HML 420.7 g (as solid content), ion-exchanged water 900 g, colorant dispersion 1 166 g and crystalline compound dispersion 210 g were attached with a temperature sensor, a cooling pipe, a nitrogen introducing device and a stirring device. The mixture was placed in a reaction container (four-necked flask) and stirred. After adjusting the temperature in the container to 30 ° C., a 5 mol / L sodium hydroxide aqueous solution was added to this solution to adjust the pH to 8 to 10.0.

Then, magnesium chloride hexahydrate 1
An aqueous solution prepared by dissolving 2.1 g in 1000 ml of ion-exchanged water was added with stirring at 30 ° C. for 10 minutes. The temperature was started after standing for 3 minutes, and this system was heated to 90 ° C. over 40 minutes to generate associated particles. In that state, the particle size of the associated particles was measured with "Coulter Counter TA-II", and when the volume average particle size reached 5 µm, 80.4 g of sodium chloride was added to ion-exchanged water 1000
Add an aqueous solution dissolved in ml to stop particle growth,
Further, as the aging treatment, the particles were continuously fused by heating and stirring at a liquid temperature of 85 to 98 ° C. for 2 to 12 hours (aging step).

Then, the mixture was cooled to 30 ° C., hydrochloric acid was added to adjust the pH to 2.0, and stirring was stopped. The formed associated particles are filtered, repeatedly washed with ion-exchanged water at 45 ° C., and then dried with warm air at 40 ° C.,
Colored particles were obtained.

The volume average particle diameter of the colored particles is 5.0 μm.
The average circularity was 0.96, and the variation coefficient of the volume average particle size was 17%.

0.5% by mass of hydrophobic silica having an average primary particle diameter of 35 nm was added to the colored particles obtained as described above, and the peripheral speed of the rotor of a 10 L Henschel mixer was 30 m / m.
s and mixed for 25 minutes. The shape and particle size of these colored particles are not changed by the addition of external additives.

Further, 1.0 mass% of barium sulfate (BET specific surface area: 20 m ² / g) having a mass average particle diameter of 200 nm, which is obtained by coating tin oxide with this toner, was added. This was mixed for 25 minutes with the rotor blade peripheral speed of a 10 L Henschel mixer set to 30 m / s. This toner is the magenta toner of the present invention.

Preparation of Comparative Toner Comparative Magenta Toner (2) A magenta toner was prepared in the same manner as the magenta toner, except that the associated particles were melted and heated to form block-like particles, which were crushed and classified repeatedly to obtain a volume average particle size of 5 Toner of 1 μm was obtained. Average circularity is 0.93, coefficient of variation of volume average particle size is 27%
Met. This is designated as comparative magenta toner (2).

Manufacture of Carrier Manufacture of Ferrite Core Material 18 mol% MnO, 4 mol% MgO, Fe ₂ O ₃
78 mol% was pulverized with a wet ball mill for 2 hours, mixed and dried, and then temporarily calcined by holding at 900 ° C. for 2 hours, and this was pulverized with a ball mill for 3 hours to form a slurry. A dispersant and a binder were added, the mixture was granulated by a spray dryer, dried, and then main-baked at 1200 ° C. for 3 hours to obtain ferrite core material particles having a resistance value of 4.3 × 10 ⁸ Ω · cm.

Production of coating resin First, 1,1,1 was prepared by an emulsion polymerization method using sodium benzenesulfonate having an alkyl group having 12 carbon atoms as a surfactant and the concentration in an aqueous medium was 0.3% by mass.
A copolymer of 1-trifluoroethyl methacrylate / methyl methacrylate (copolymerization ratio 2/8) was synthesized, and the volume average primary particle size was 0.1 μm and the weight average molecular weight (Mw) was 20.
50,000, number average molecular weight (Mn) 91,000, Mw
Resin fine particles having /Mn=2.2, a softening point temperature (Tsp) of 230 ° C. and a glass transition temperature (Tg) of 110 ° C. were obtained.
The resin fine particles were azeotroped with water in the emulsified state, and the residual monomer amount was 510 ppm.

Next, 100 parts by mass of the ferrite core material particles and 2 parts by mass of the resin fine particles are put into a high-speed stirring mixer having a stirring blade, and stirred and mixed at 120 ° C. for 30 minutes to utilize the action of mechanical impact force. Thus, a resin-coated carrier having a volume average particle diameter of 61 μm was obtained.

Preparation of Developer Magenta toner of the present invention to which an external additive was added and comparative magenta toner were mixed with a carrier, and the magenta developer of the present invention having a toner concentration of 6% by mass was compared with magenta developer. Agent (2) was prepared.

2. Preparation of Photoreceptor A cylindrical conductive support having a length of 380 mm and a diameter of 40 mm was coated with the following coating liquid to prepare a photoreceptor P1.

<Undercoating Layer> Titanium chelate compound (TC-750 manufactured by Matsumoto Pharmaceutical Co., Ltd.) 30 g Silane coupling agent (KBM-503 manufactured by Shin-Etsu Chemical Co., Ltd.) 17 g 2-propanol 150 ml Cylindrical conductive support using the above coating liquid A film thickness of 0.
It was applied so as to have a thickness of 5 μm.

<Charge Generation Layer> Y-type titanyl phthalocyanine (titanyl phthalocyanine having a maximum peak at 27.2 ° of Bragg angle 2θ (± 0.2 °) in Cu-Kα characteristic X-ray diffraction spectrum measurement) 60 g Silicone modified Butyral resin (X-40-1211M: manufactured by Shin-Etsu Chemical Co., Ltd.) 700 g 2-butanone 2000 ml was mixed and dispersed for 10 hours using a sand mill to prepare a charge generation layer coating solution. This coating solution was applied onto the undercoat layer by a dip coating method to form a charge generation layer having a thickness of 0.2 μm.

<Charge Transport Layer> Charge Transport Material N- (4-methylphenyl) -N- {4- (β-phenylstyryl) phenyl} -p-toluidine 225 g Polycarbonate (viscosity average molecular weight 30,000) 300 g Dichloromethane 2000 ml Were mixed and dissolved to prepare a charge transport layer coating solution. This coating solution was applied onto the charge generation layer by a dip coating method to form a charge transport layer having a dry film thickness of 20 μm.

<Surface protection layer> Methyltrimethoxysilane 150 g Dimethyldimethoxysilane 30 g Polyvinylidene fluoride particles (volume average particle size 0.2 μm) 10 g 2-Propanol 75 g 3% acetic acid 5 g are mixed, and a coating solution for the surface protection layer is mixed. Was prepared. A resin layer having a thickness of 2 μm was formed from the coating solution on the charge transport layer by a circular amount regulation type coating device, followed by heat curing at 120 ° C. for 1 hour to form a surface protective layer of a siloxane resin.

Example 1 Using the magenta developer of the present invention and the comparative magenta developer (2), using the image forming apparatus shown in FIG.
In a% RH environment, a magenta image is formed, and the fog (absolute reflection density) of the 10,000th image, resolution (number of fine lines / mm)
Images with different widths were formed, and the number of decipherable films was evaluated.

Evaluation Results Fog Resolution Magenta Developer of the Present Invention 0.001 9 Comparative Magenta Developer (2) 0.002 6 From the above results, the magenta developer of the present invention has good characteristics, but comparative magenta development. Agent (2) does not have good properties. This is considered to be because the comparative magenta developer (2) does not have a spherical toner particle shape and has various shapes, so that the chargeability varies and toner scattering occurs.

It can be seen that it is necessary to use toner having a high average circularity in order to obtain a clear and high-resolution image required as a premise of the present invention.

Example 2 Using the magenta toner of the present invention used in Example 1 and a magenta toner containing no barium sulfate as a comparative magenta toner (others were prepared in the same manner as in the present invention), 10
The following evaluations were made in a live-action test of 10,000 copies.

The elastic rubber blade used for cleaning had a thickness of 2 mm, a free blade length of 9 mm, a blade contact angle of 20 degrees in the counter direction, and a normal load of 0.2 N / cm. .

The transfer residual toner amount is 0.05 to 0.3 (g /
The cleaning state of the surface of the photoconductor whose amount was changed to cm ² ) was checked with the naked eye and a magnifying glass (30 times). The magenta toner of the present invention has a transfer residual toner amount of 0.2.
Up to (g / cm ² ), no filming was found on the surface of the photoconductor and good results were obtained, while the magenta toner for comparison was 0.05 (g / cm ² ). Good cleaning was managed somehow, but when the transfer residual toner amount was more than that, good cleaning was not possible, and filming was observed on the surface of the photoconductor.

An actual shooting test was conducted in the same manner as in Example 1, except that the elastic rubber blade was loaded with a load of 0.18 in the normal direction.
The variables were 0.2, 0.22 and 0.24 (N / cm).

The result is shown in the graph of FIG. Under any of these load conditions, it can be seen that the one in the present invention to which barium sulfate was added as the external additive can sufficiently clean the region where the transfer residual toner amount is large. In the graph, those that were sufficiently cleaned and did not cause filming were indicated by ◯, and those that could not be sufficiently cleaned were indicated by x.

Example 3 1. Preparation of Toner 1) Yellow Toner A yellow toner of the present invention was prepared in the same manner as the above magenta toner, except that the colorant was changed from a quinacridone magenta pigment to 420.0 g of a benzidine yellow pigment.
A comparative yellow toner was prepared without the addition of barium sulfate.

2) Cyan Toner The toner was prepared in the same manner as the magenta toner, except that the quinacridone magenta pigment was changed to 300.0 g of the phthalocyanine cyan pigment as the colorant, and the cyan toner of the present invention and barium sulfate were added. A comparative cyan toner was prepared.

3) Black Toner A black toner of the present invention and sulfuric acid were prepared in the same manner as the above magenta toner, except that a quinacridone type magenta pigment was used as a colorant to obtain 420.0 g of carbon black (Regal 330, manufactured by Cabot Corporation). A comparative black toner was prepared without the addition of barium.

The image forming apparatus shown in FIG. 2 was used, and the magenta toner used in Example 2, the yellow toner, the cyan toner and the black toner produced as described above were used and compared with the toner of the present invention. The toner was paired with each other and a 200,000-copy actual shooting test was conducted.

The pressure contact load of the elastic rubber blade was 0.22 N / cm in the normal direction, and a color gradation original was used.

Toner combinations are the following 1) and 2).
It combined like. 1) Any of the yellow toner, magenta toner, and
Cyan toner, black toner 2) Comparative yellow toner, comparative magenta toner, comparative cyan toner, comparative black toner In the case of the combination of toner 1) in the present invention, residual toner on the photoconductor even after a 200,000-copy actual copying test. Was set to 0.3 mg / cm ² and cleaning was performed sufficiently with an elastic rubber blade.

However, in the combination of 2) outside the present invention,
Is 0.05 mg / cm of residual toner ²More than
Could not be cleaned sufficiently.

[0124]

EFFECTS OF THE INVENTION According to the present invention, the electrostatic adhesion between the electrophotographic photosensitive member surface and the toner can be reduced and sufficient cleaning can be performed on the assumption that a small particle diameter toner having a high average circularity is used to obtain a high quality image. At the same time, the load on the elastic rubber blade for cleaning is reduced to prevent toner from slipping through the blade and filming on the photoconductor, and the durability of the blade and the electrophotographic photoconductor is also secured. Can be provided.

[Brief description of drawings]

FIG. 1 is a configuration cross-sectional view for explaining an elastic rubber cleaning blade.

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

FIG. 3 is a graph chart in which the cleaning property is evaluated in a 10-sheet actual copying test.

[Explanation of symbols]

1, 1Y, 1M, 1C, 1K Photoconductor (photoconductor drum) 2Y, 2M, 2C, 2K charging means 3Y, 3C, 3M, 3K exposure means 4Y, 4C, 4M, 4K developing means 6 Intermediate transfer body 7Y, 7M, 7C, 7K Transfer means (primary transfer means) 7A Transfer means (secondary transfer means) 8, 8Y, 8M, 8C, 8K Cleaning means 10Y, 10M, 10C, 10K Image forming unit 13 Concentration detection sensor 24 Fixing device

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 15/01 G03G 21/00 318 15/08 507 9/08 361 21/10 384 (72) Inventor Kurosu Shigeru, Konica stock company, 2970, Ishikawa-cho, Hachioji, Tokyo (72) Inventor, Masashi Saito F-term, Konica stock company, 2970, Ishikawa-cho, Hachioji, Tokyo (reference) 2H005 AA08 AA15 AA21 AB06 CB07 CB08 CB13 DA08 EA05 EA10 2H030 AD01 AD03 BB02 BB42 2H077 AC04 AD06 GA13 2H134 GA01 GB02 HD04 HD05 HD11 HD19 KD05 KG07 KH01 KH15 KJ02

Claims (6)

[Claims] 1. A multicolor color image is formed by using an electrophotographic photosensitive member used repeatedly for image formation and a plurality of developing devices each loaded with color toner having an average circularity of 0.95 to 0.99. In an image forming apparatus in which an elastic rubber blade is used for cleaning the photosensitive member, silica particles as an external additive and a weight average particle diameter (D50) of 100 to 100 are used for at least one color toner. An image forming apparatus, wherein inorganic fine particles of 1000 nm are added. 2. The image forming apparatus according to claim 1, wherein the toner to which the inorganic fine particles are added is any one of yellow, magenta, and cyan toners. 3. The image forming apparatus according to claim 1, wherein the inorganic fine particles are barium sulfate coated with tin oxide. 4. The BET specific surface area of the inorganic fine particles is 10
The image forming apparatus according to claim 1, wherein the image forming apparatus has a thickness of about 30 m ² / g. 5. The image forming apparatus according to claim 1, wherein each of the color toners has a volume average particle diameter of 3 to 8 μm. 6. The image forming apparatus according to claim 1, wherein each of the color toners is manufactured by a polymerization method.