JPS63174059A - Electrostatic image developer and electrostatic image developing method - Google Patents

Abstract

PURPOSE:To stabilize the triboelectrification property of a toner for a long period of time by incorporating a carrier coated with a resin, toner contg. a nigrosine dye and fine inorg. particles to be electrostatically charged positive by friction with the carrier into a developer. CONSTITUTION:This developer contains the carrier formed by coating magnetic material particles with the resin (e.g.: silicone rubber), the toner formed by dispersing the nigrosine dye into a binder (e.g.: styrene/acrylic copolymer) and the fine inorg. particles such as silica which are subjected to a surface treatment with, for example, amino modified silicone compd. so as to be electrostatically charged positive by friction with the carrier. The negative electrostatic latent image formed on the surface of a photosensitive body 10 is formed by a contact type magnetic brush development method using the above-mentioned developer 22. Then, the positive triboelectrified charge is surely imparted to the toner and, therefore, the images having a high image density without having fogging are stably obtd. even in high-humidity environment.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an electrostatic image used for developing an electrostatic latent image formed in electrophotography, electrostatic recording, electrostatic printing, etc. The present invention relates to a developer and an electrostatic image developing method for developing an electrostatic latent image formed on the surface of a photoreceptor made of an organic photoconductive semiconductor using the electrostatic image developer,
In particular, the present invention relates to an electrostatic image developer and an electrostatic image developing method suitable for developing a negative electrostatic latent image formed on the surface of a photoreceptor made of an organic photoconductive semiconductor.

[Background of the invention]

Generally, in electrophotography, a photoreceptor having a photosensitive layer made of a photoconductive material is given a uniform electrostatic charge, and then an electrostatic latent image is formed on the surface of the photoreceptor by performing image exposure. This electrostatic latent image is developed with a developer to form a toner image. The obtained toner image is transferred to a transfer material such as paper and then fixed by heating or pressure to form a copy image.

Examples of the photoconductive material used to form the photosensitive layer of the photoreceptor include inorganic photoconductive materials such as selenium, zinc oxide, and cadmium sulfide, and organic photoconductive materials made of high molecular compounds or low molecular weight compounds such as polyvinyl carbazole. There are known materials such as carbonaceous materials.

However, although photoreceptors having photosensitive layers formed from these photoconductive materials have one advantage in forming electrostatic latent images, they also have drawbacks specific to various photoreceptors. have.

For example, in a photoreceptor having a photosensitive layer formed of selenium, the photosensitive layer easily crystallizes due to heat or metal compounds contained in the developer or transfer material, deteriorating its properties, resulting in an electrostatic latent image. There is a problem that the potential of the image decreases, resulting in a decrease in image density or partial image blanking. In addition, under high humidity environmental conditions, the photoconductivity of the photosensitive layer decreases and static charges remain in the non-image areas of the photoreceptor, resulting in capri formation and making it difficult to obtain clear images. First, under high humidity environmental conditions, good images cannot be formed many times and durability is low.

In addition, photoreceptors having a photosensitive layer formed of cadmium sulfide or a photoreceptor having a photosensitive layer formed of zinc oxide usually have a photoconductive material, ie, cadmium sulfide or zinc oxide, dispersed in a Pai Goo resin. A photosensitive layer is formed, but it is quite difficult to uniformly disperse such a photoconductive material in the form of fine particles in a binder resin, and as a result, the resulting photoreceptor has low sensitivity and is unsuitable for high-speed copying. In addition, the photosensitive layer tends to deteriorate early in the corona charging process or exposure process that is normally used to form an electrostatic latent image, making it difficult to maintain a good image over a long period of time. Furthermore, under high-temperature environmental conditions, the characteristics of the photosensitive layer change due to moisture, making it impossible to obtain the desired electrostatic latent image potential, resulting in a low image density. There is.

On the other hand, organic photoreceptors having a photosensitive layer formed from a polymeric photoconductive material typified by polyvinylcarbazole have good film-forming properties and can be manufactured at low cost. It has been attracting attention in recent years due to its advantages such as non-toxicity, but on the other hand, it has low sensitivity and is prone to early deterioration during the corona charging process or exposure process, resulting in poor durability. Since the charge retention ability is easily changed, it is still inferior to photoreceptors having a photosensitive layer made of an inorganic photoconductive material, and the development of a high-performance photoconductive material is desired.

On the other hand, in order to overcome the above problems, it has recently been proposed to use low molecular weight organic photoconductive materials. Since low molecular weight organic photoconductive materials generally have good dispersibility in binder resins, the resulting photosensitive layer has the organic photoconductive materials uniformly dispersed in the form of fine particles, resulting in a high sensitivity. By forming the photosensitive layer by dispersing an organic photoconductive material in a binder resin, it is possible to obtain a photoreceptor with relatively high performance, and by forming the photosensitive layer by dispersing an organic photoconductive material in a binder resin, the film forming property is good, and therefore the photoreceptor can be manufactured with high productivity. In addition, there are many types of low molecular weight photoconductive materials that can be used, and therefore, by using appropriately selected low molecular weight photoconductive materials, it is possible to obtain photoreceptors with better performance than conventional ones. It is possible. Thus, an organic photoreceptor having a photosensitive layer formed of a low molecular weight organic photoconductive material is more preferable than conventional photoreceptors.

However, since organic photoconductive materials usually exhibit photoconductivity through the movement of positive charges, it is difficult to form photoconductive materials on the surface of an organic photoreceptor that has a photosensitive layer formed from the organic photoconductive material. The polarity of the electrostatic latent image is preferably negative. In order to develop a negative electrostatic latent image, it is necessary to use a developer containing positively charged toner.

However, in the conventionally widely used photoreceptor having a photosensitive layer made of selenium, etc., the polarity of the electrostatic latent image formed on the surface is positive, so it is difficult to develop the electrostatic latent image. Developers containing negatively charged toner are used, and considerable research and development efforts have been made on developing agents containing negatively charged toner. Research and development of developers containing toner is still lagging behind, and the reality is that a developer containing a sufficiently positively charged toner has not been obtained.

On the other hand, wet developing methods and dry developing methods are known as methods for developing electrostatic latent images. The former wet development method is
Since a liquid developer is used, there is a problem in that it emits a bad odor, and there is also a problem in that high-speed copying is difficult because high energy is required to dry the transfer material. The latter dry developing method does not have such problems and can be preferably used as a developing method for electrostatic latent images.

The developers used in the dry development method include a so-called one-component developer consisting only of a magnetic toner containing a magnetic substance, and a so-called two-component developer consisting of a non-magnetic toner that does not contain a magnetic substance and a magnetic carrier. type developer is known.

The former one-component developer consists only of magnetic toner and does not have a carrier, so there is some frictional electrification caused by the toners and the height of the toner and the developing sleeve or developer layer placed in the developing device is controlled. The toner is charged by frictional charging with the regulating blade, etc., and as a result, both positively charged toner and negatively charged toner exist, and because the amount of triboelectric charge is small, development is basically unstable. There are some problems that can easily become a problem. Specifically, for example, toner may adhere to non-image areas on the photoconductor, causing capri in the final fixed image, or insufficient amount of toner may adhere to the image area on the photoconductor, causing the final There is a problem that the density of the fixed image becomes low.

In addition, the magnetic material used in magnetic toner usually has hydrophilic properties, and since this hydrophilic magnetic material is often contained in an exposed state on the surface of toner particles, the toner becomes triboelectrically charged due to moisture. Charge tends to leak, and in high-temperature environments, electrostatic transfer to the transfer paper normally used as a transfer material becomes defective during the transfer process, resulting in a low toner transfer rate to the transfer paper. There is a problem that the density of the final fixed image decreases. In addition, since the magnetic material used in magnetic toner usually has negative chargeability, it is difficult to positively charge the magnetic toner with an appropriate amount of charge, and as a result, a large proportion of toner with the opposite polarity exists. There are problems in that the density of the final fixed image decreases and image unevenness occurs.

On the other hand, the latter two-component developer is composed of toner and carrier, and the carrier has the function of charging the toner to a desired polarity. It is possible to impart a triboelectric charge depending on the amount, and it is possible to obtain a developer having much superior triboelectric chargeability compared to the one-component developer described above.

Further, by selecting a carrier having desired characteristics, it is possible to control the amount of charge of the toner to a considerable extent.

However, in order to obtain a good final fixed image, it is not enough that the developer has good triboelectric chargeability, and particles of the developer to which triboelectric charge has been applied do not aggregate in the developing device. It is necessary that the film be transported to the developing space in good condition without any damage.

In other words, in a two-component developer, if the toner tends to aggregate and form clumps due to electrostatic cohesive force, it becomes difficult to disperse the toner particles in the carrier particles at a uniform concentration. The triboelectricity of the toner and carrier decreases, and the proportion of toner with low triboelectricity increases, and in the developing process, toner adheres to non-image areas on the photoreceptor, causing fog in the final fixed image. In addition, there is a large amount of weakly charged toner, and the electrostatic adhesion force between the toner and the carrier is small. Therefore, in the magnetic brush development method, the toner particles attached to the carrier particles are removed while rotating the carrier particles by magnetic force. When conveyed to the developing space, toner particles scatter due to centrifugal force due to the rotation of the carrier particles, and as a result, they contaminate various devices such as the charger and exposure optical system installed in the copying machine, and the final fixation is interrupted. There is a problem that image defects such as image unevenness occur in the image.

However, in conventional negatively charged toners, fine silica particles having a smaller diameter than the toner particles are mixed with the toner particles to attach the fine silica particles to the surface of the toner particles, thereby preventing the toner from clumping. This is done to obtain high liquidity.

However, conventionally used silica fine particles have strong negative chargeability, so when obtaining a positively chargeable toner, if silica fine particles are mixed with the toner and attached to the surface of the toner particles, the resulting toner will be negatively charged. It becomes electrostatic,
As a result, the polarity becomes the same as the negative electrostatic latent image formed on the photoreceptor, and there is a problem that electrostatic development cannot be performed.

[Problem that the invention seeks to solve]

Under these circumstances, research and development of positively chargeable fine particles has been progressing recently, but it has been found that there is a new problem.

That is, by being mixed with the toner, these positively charged inorganic fine particles are held attached to the toner particles, and when they are mixed with carrier particles and stirred, they impart positive friction to the toner. A charge is imparted to the surface of the toner particles, but since conventional two-component developers use a carrier made of iron powder particles, when the toner and carrier are stirred in the developing device, the surface of the toner particles is The positively charged inorganic fine particles that had been attached to the carrier particles are now transferred to the surface of the carrier particles due to physical or electrostatic adhesion, and the amount of transfer increases each time the carrier is used repeatedly. As a result, the frictional charging characteristics between the toner and the carrier change, and the amount of weakly charged toner increases, and furthermore, the amount of toner that is negatively charged increases, resulting in fogging and image distortion in the resulting image. Phenomenon in which areas are missing (image missing), differences in shading appear in the image (image unevenness), phenomena in which the density decreases in the peripheral areas of the image (image blur), and phenomena in which band-shaped differences in shading appear in the image (image fading) ) occurs and the image becomes unclear. Furthermore, when forming an image many times, the positive chargeability of the toner decreases significantly, resulting in an early decrease in image density (
However, there are problems in that the image becomes unclear and the durability of the developer is low.

In addition, weakly charged toner or toner of opposite polarity tends to scatter, which contaminates the inside of the apparatus, resulting in the problem that the image becomes smudged and unclear.

Furthermore, conventional two-component developers have a problem in that the triboelectric charging characteristics of the developer are poor. In other words, the required stirring time from the start of stirring of the developer in the developing device until the amount of triboelectric charge of the toner reaches the appropriate value required for development is considerably long, and as a result, a lot of fogging occurs, especially in the early stages of image formation. However, there is a problem that the initial image becomes unclear. This problem becomes particularly serious when the developer is left unstirred for a long time, such as when images are formed first thing in the morning.

[Purpose of the invention]

The present invention has been made based on the above-mentioned circumstances, and its objects are as follows: (1) to have good positive chargeability, to produce high-quality images with high image density and no fog over and over again; (2) To provide an electrostatic image developer that can stably form good images regardless of environmental conditions; 3) To provide an electrostatic image developer that has good triboelectric charging properties and can form a clear image without fogging even in the initial stage of image formation; (4) to provide an electrostatic image developer that can be formed on an organic photoconductive photoreceptor; An object of the present invention is to provide an electrostatic image developing method capable of satisfactorily developing a negative electrostatic latent image without scattering of toner.

[Means for solving problems]

The electrostatic image developer of the present invention comprises a carrier formed by coating magnetic particles with a resin, a toner containing a nigrosine dye, and inorganic fine particles (hereinafter referred to as "positively charged") that are positively charged by friction between the carrier and the carrier. Also referred to as chargeable inorganic fine particles (j).

In the electrostatic image developing method of the present invention, a carrier formed by coating magnetic particles with a resin, a toner containing a nigrosine dye, and a non-I which is positively charged by friction between the carrier and the carrier are provided.
Using an electrostatic image developer (hereinafter also referred to as "specific developer") containing m fine particles, the surface of a photoreceptor (hereinafter also referred to as "organic photoreceptor") made of an organic photoconductive semiconductor is used. The negative electrostatic latent image formed on the image is developed by a contact magnetic brush development method.

[Function and effect of the invention]

The electrostatic image developer of the present invention contains a carrier having a coating layer made of resin, a toner containing a nigrosine dye, and inorganic fine particles that are positively charged by friction with the carrier. The synergistic effect of these makes it possible to reliably apply a positive and appropriate amount of triboelectric charge to the toner, and as a result, images with high image density and good image quality without capri can be produced many times. It can be stably formed over a long period of time. In addition, good triboelectric charging properties of the toner can be stably obtained regardless of environmental conditions, so images with high image density and fog-free quality can be stably formed many times even under high-temperature environmental conditions. be able to. Furthermore, since the developer has good triboelectric charging characteristics, it is possible to form an initial image of good image quality without fogging even in the initial stage of image formation.

In other words, the presence of a coating layer made of resin in the carrier reduces the surface energy of the carrier particles and improves the surface slipperiness, making it difficult for positively charged inorganic particles to adhere to the carrier particles, and toner particles. Adhesion of the substance to the carrier particles becomes difficult, and as a result, the toner can stably exhibit good triboelectric charging properties over a long period of time. Furthermore, since the carrier having a coating layer made of resin has stable triboelectric charging properties even under changes in environmental conditions, it is possible to impart a stable triboelectric charge to the toner even under particularly high temperature environmental conditions. can. In addition, a carrier having a coating layer made of resin,
It has excellent durability and can be used repeatedly many times.

Since the toner contains a nigrosine dye, its triboelectric charging properties with the carrier are significantly improved, so even if the developer is left unstirred for a long time, it can be developed in the developing device. The required stirring time from the start of stirring of the agent until the amount of triboelectric charge of the toner reaches the appropriate value required for development is shortened, and as a result,
Even in the initial stage of image formation, capri does not occur and an initial image of good quality can be formed.

According to the electrostatic image developing method of the present invention, a negative image formed on the surface of an organic photoreceptor, that is, a photoreceptor made of an organic photoconductive semiconductor, is formed by a contact magnetic brush development method using a specific developer as described above. To develop a negative electrostatic latent image formed on the organic photoreceptor, the negative electrostatic latent image formed on the organic photoreceptor can be developed without toner particle scattering, without sacrificing the advantages of organic photoreceptors such as low production cost and non-toxicity. Good development can be achieved without any problems. In other words, since the specific developer mentioned above has excellent positive charging properties, it becomes positively charged with an appropriate amount of charge, so that the carrier particles and toner particles form a uniform brush shape on the developing sleeve. The developer layer (magnetic brush) is carried in a thin layered form arranged side by side, and the developer layer (magnetic brush) in this form is stably transported to the developing space while maintaining this form, which reduces contamination due to scattering of toner particles. Occurrence can be prevented. In addition, the presence of positively charged inorganic particles gives the developer excellent fluidity, making it possible to form a uniform and uniform magnetic brush on the developing sleeve. This makes it possible to achieve good development.

In conclusion, according to the developer and developing method of the present invention, clear and good quality images without capri are generated and are free from image unevenness, image blanking, image blurring, and image fading, regardless of environmental conditions. It is possible to stably form images many times, and even in the initial stage of image formation, it is possible to form images of good quality without fogging.

(Specific Structure of the Invention) The carrier constituting the electrostatic image developer of the present invention is formed by providing a coating layer made of resin on the surface of magnetic particles.

As the resin for forming the coating layer of the carrier, for example, silicone compounds, fluororesins, etc. can be preferably used.

As the silicone compound, for example, silicone rubber, silicone varnish, silicone resin, or cured products thereof can be preferably used. Further, a plurality of types of silicone compounds may be used in appropriate combination.

Furthermore, as the silicone rubber, silicone varnish, and silicone resin, those having an organic group such as an alkyl group or an aromatic group as a constituent unit are preferable, and those having an organic group such as a methyl group or a phenyl group are particularly preferable. Specific examples of silicone compounds having such organic groups include dimethylsiloxane, methylphenylpolysiloxane, diphenylpolysiloxane, and modified products thereof. In particular, a polysiloxane having a methyl group or a phenyl group has excellent negative charging properties, and when a carrier provided with a coating layer made of polysiloxane and a toner are triboelectrically charged, the toner is positively charged. have an effect. And in the above ia group, a methyl group,
By appropriately selecting the content ratio of phenyl groups, it is possible to adjust the properties such as hardness, toughness, and triboelectric charging properties of the coating layer of the carrier. This has the advantage that the conditions are considerably relaxed and the range of toner selection is wide.

As the silicone varnish, for example, "5R21θ
1", rSH997J, rsH994J, "5R220
2J, r R-4-3117J, r S R9140J
, "5H643J, r S H2O47J, r J C
R6100J, [JCR6101J, r J CR61
02J, rsH6103J (manufactured by Tomu Silicone Co., Ltd.), rKR271J, r, KR272J, r
KR2T4J, r K R216J, “KR280J,
rKR282J, rKR261J, rKR260'', r
KR255J, rKR266J, rKR251J, rK
R155J, rKR152J, rKR214J, “KR
220J, rX-40-171J, rX-40-172
J, rX-40-1902J, rX-40-1903
J, rX-40-1905J, rX-40-260
5B J, rKR201J, rsA-4J, rK
R5202J, rK R5203J, rK R30
93J, rEcloolJ, rX-41-970
1J (manufactured by Shin-Etsu Chemical Co., Ltd.), etc. can be used.

As the silicone rubber, for example, [5H410]
, rsl (432j, rsH433J, r S ) (7
40'', r S ) (745tJ J, rsH746U
J, rsH747UJ, rsH748UJ, rsH35
UJ, rsH55UJ, rsH75UJ, rsH52U
J, rSH82UJ, rsH841UJ, rsH851
UJ, rsH1125UJ, r S It 1150U
J, rsH1603UJ, rsH665UJ, rS
E955U J, rs) (502UJ, rsRX-4
40UJ (manufactured by Tomu Silicone Co., Ltd.), etc. can be used.

As the silicone resin, for example, "5H804"
, rsH805J, rsH806AJ, rSH808"
, rsH840J, rS R2107J, rsR21
08J, r S R2400J, rSR620J (
(manufactured by Tomu Silicone Co., Ltd.), etc. can be used.

In addition, when forming a carrier coating layer using the above-mentioned silicone compound, a curing agent may be used as necessary. Examples of such curing agent include benzoyl peroxide, 2,4-dichlorobenzoyl Peroxides such as peroxide, dicumyl peroxide, ditertiary butyl peroxide, and tertiary butyl perbenzoate; lead, iron, cobalt, such as octylic acid and naphthenic acid;
Examples include metal soaps such as manganese and zinc; organic amines such as ethanolamine; and the like.

In addition, the fluororesin that can be used as the coating resin for the carrier is not particularly limited as long as it contains fluorine atoms, but for example, a monomer represented by the following general formula (■) or (■) may be polymerized. Polymers made of polyester, vinylidene fluoride-ethylene tetrafluoride copolymers, etc. can be preferably used.

General formula ■ R'1 GHz = C Coo (CHz), IC-Ft-, + General formula ■ R"CHz" C Coo (CH, (CF, H) (RI l and RI 1 are each a hydrogen atom or represents a methyl group, n and p each represent an integer of 1 to 8, and m and q each represent an integer of 1 to 19). Among them, methacrylic #-1,1-dihydroperfluoroethyl, methacrylic acid-1,1,3-)rihydroverfluoro n-propyl, etc. can be particularly preferably used.

In addition, when using a vinylidene fluoride-tetrafluoroethylene copolymer, the copolymerization molar ratio of these is 75
: 25 to 95:5 is preferred, and 75,725 to 87.5 : 12.5 is particularly preferred. By using a substance within this range, the coating liquid used for forming the coating layer becomes easily soluble in the solvent, making it easy to prepare the coating liquid, and also making it easier to prepare the coating liquid used for forming the coating layer. It becomes possible to obtain a resin-coated carrier with high physical strength and excellent durability.

Furthermore, even if the fluororesin has high solubility in solvents, if the molecular weight of the fluororesin is excessive, the viscosity of the coating liquid will increase, making it difficult to form a uniform coating layer. Pinholes may occur or durability may decrease.On the other hand, if the molecular weight of the fluororesin is too low, problems such as a decrease in the mechanical strength of the coating layer are likely to occur. In the present invention, a fluororesin having an intrinsic viscosity (in methyl ethyl ketone, 30° C.), which is a measure of molecular weight, in the range of 0.1 d17 g to 5 dl/g can be preferably used.

In forming the fluororesin, other monomer components may be used in addition to the monomer components described above. Examples of such other monomer components include acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate,
Acrylic monomers such as butyl acrylate, butyl methacrylate, benzyl acrylate, benzyl methacrylate, glycidyl acrylate, glycidyl methacrylate; styrene and its derivatives; vinyl esters such as vinyl acetate and vinyl butyrate; etc. be able to.

Specific examples of fluororesins include those represented by the following structural formulas, but are not limited thereto. In addition, in the following structural formula, n represents an integer of 1 or more.

Exemplary polymer (1) CH.

l.

+CHg-C+r- C00CT(ICF3 Exemplary polymer (2) CH.

+CH1-C±" COOCHt CF t CF s Exemplary polymer (3) CH, C) Summer.

+CH2-C-)T"--1-→CHz-C-)TCO
OCHzCCFt)tHC00CHs Exemplary Polymer (4) CH3 +CH2-C→1- COOCH, (CFz)4H Exemplary Polymer (5) HH I3 +CHz C+T- C00CHz(CFz)icFt Exemplary Polymer (7) CM.

+CHtC-;])・・・・・・・]]i:;00CH
f(CF2)SH Exemplary polymer (8) CH3GHz I +CHz C, CHz-C+" COOCH2 (CFri ICFI C00CH.

In forming the carrier coating layer, each of the above-mentioned fluororesins may be used alone, or a blend of these may be used.

When the carrier coating layer is formed using the silicone compound and fluororesin described above, the adhesive strength with the magnetic particles is sufficiently high, so the carrier has significantly superior impact resistance. becomes.

In addition, in forming the coating layer of the carrier, other resins may be used in addition to the silicone compounds and fluororesins described above. Examples of such other resins include styrene-acrylic resins, polyurethane,
Polyester etc. can be used.

In the present invention, the magnetic particles constituting the carrier include substances that are strongly magnetized in the direction of a magnetic field, such as iron, ferrite, magnetite, and other ferromagnetic metals or alloys such as iron, nickel, and cobalt. Compounds containing the elements, alloys that do not contain ferromagnetic elements but become ferromagnetic through appropriate heat treatment, such as alloys called Heusler alloys such as manganese-copper-aluminum or manganese-copper-tin. Alternatively, particles made of chromium dioxide or the like can be used.

In the present invention, the method for producing a carrier having a resin coating layer on the surface of magnetic particles is not particularly limited, but in specific examples, for example, the coating resin component or the necessary A coating liquid prepared by dissolving a curing agent or the like to be used in a solvent is applied to the surface of the magnetic particles, and then usually heated and dried to volatilize and remove the solvent.

The carrier used in the present invention can be manufactured by thermally curing the coating layer during or after drying, if necessary.

The coating method for applying the above-mentioned coating liquid to the surface of the magnetic particles is not particularly limited, but includes, for example, a dipping method in which powder of the magnetic particles is immersed in the coating liquid, and a method in which the coating liquid is sprayed onto the magnetic particles. A spray method, a fluidized bed method in which magnetic particles are suspended with fluidized air and a coating liquid is sprayed onto the suspended magnetic particles, and a method in which magnetic particles are transferred onto the surface where the coating liquid is present are used. be able to. In particular, when the fluidized bed method is used, it is possible to form a uniform coating film on the surface of the magnetic particles, and a coating layer with uniform properties can be stably formed.

This fluidized bed coating method is described in, for example, Japanese Patent Application Laid-open No. 155049/1983.

Additives may be added to the coating liquid as necessary. The solvent is not particularly limited as long as it dissolves the coating resin component, but examples include aromatic hydrocarbons such as toluene and xylene; ketones such as acetone and methyl ethyl ketone; tetrahydrofuran, dioxane, higher alcohols, and dimethyl Solvents such as hydrocarbon compounds having sulfoxide, fluorine and/or halogen substituents, or mixed solvents thereof can be used.

The thickness of the coating layer in the carrier is not particularly limited, but it is preferably a thickness that can impart a positive triboelectric charge to the toner by frictional charging with the toner, specifically, 0.01 The thickness is preferably about 5.0 μm, particularly preferably 0.1 to 3 n. If the thickness of the coating layer is too small, the durability of the carrier may be reduced, while if the thickness of the coating layer is too large, the coating layer is likely to peel off, and as a result, the image may become unclear. The quantitative proportion of the coating layer is preferably 0.01 to 10% by weight, particularly preferably 0.05 to 5% by weight, based on the magnetic particles. If this ratio is too small, the durability of the carrier may be reduced, while if the ratio is too large, the coating layer is likely to peel off, and as a result, the image may become unclear.

In the present invention, the average particle size of the carrier is 5 to 500.
It is preferably n, particularly preferably 20 to 150 n. When the average particle size of the carrier is too small, a so-called carrier adhesion phenomenon occurs in which the carrier adheres to the electrostatic latent image and forms a fixed image, and as a result, the image may become unclear. If the diameter is too large, image distortion may occur.

In the present invention, the carrier particles preferably have a spherical shape, and specifically, the ratio of the major axis to the minor axis (major axis/minor axis) of the carrier particles is 1.0 to 1.2.
It is preferable that when the value of the ratio is excessive,
The magnetic brush formed on the developing sleeve becomes non-uniform, resulting in poor image formation and blurred images.
Furthermore, the durability of the carrier may be reduced.

In the present invention, the average particle diameter (weight i) of the carrier is defined as "
Defined as the value measured using "Micro Track" (manufactured by Nikkiso Co., Ltd.). Further, the long axis of the carrier represents the maximum value of the outer diameter, and the short axis represents the minimum value of the outer diameter.

The inorganic fine particles constituting the electrostatic image developer of the present invention are positively chargeable inorganic fine particles that are positively charged by friction with a carrier.

In the present invention, positively charged inorganic fine particles are defined as follows.

That is, 0.2 g of positively charged inorganic fine particles left overnight under environmental conditions of a temperature of 20° C. and a relative humidity of 40%, and a carrier used in the present invention, that is, a magnetic particle having a coating layer made of resin on the surface. 19.8 g of carrier consisting of
The amount of triboelectric charge of the inorganic fine particles is measured by a normal blow-off method using a stainless steel cell having a 00 mesh screen, and those whose triboelectric charge is positive are defined as positively charged inorganic fine particles.

As the positively chargeable inorganic fine particles used in the present invention, in the above measurement, triboelectric? ;jl is preferably +10〆/g or more, particularly +30〆/g or more.

When the amount of triboelectric charge is too small, the positive triboelectricity of the toner deteriorates and the amount of triboelectricity decreases, which may result in fogging or a decrease in the durability of the developer.

As such inorganic fine particles, for example, those having a positively charged substance on their surfaces can be preferably used. Specifically, inorganic fine particles whose surfaces have been treated with an amino-modified silicone compound and which have the amino-modified silicone compound or its cured product on the surface can be preferably used. According to such inorganic fine particles, the presence of amino groups makes the inorganic fine particles excellent in positively charging properties, and the functional groups of the silicone compound and the hydrophilic groups such as hydroxyl groups present on the surface of the free fine particles. are strongly bound together, resulting in inorganic fine particles that have excellent moisture resistance and durability, and have stable positive triboelectric charging properties that are not affected by environmental conditions.

As the amino-modified silicone compound, amino-modified silane cuff pulling agent, amino-modified silicone oil, amino-modified silicone varnish, amino-modified silicone rubber, amino-modified silicone resin, etc. can be used. Amino-modified silicone varnishes, amino-modified silicone rubbers, and amino-modified silicone resins are preferred in terms of their properties.

As the amino-modified silane coupling agent, for example, the following compounds can be preferably used.

HmN CHtCHtCHg5i (OCHs)sHtN
CHICHxCHtSi(OC1Hs)s Hs HtNCHgCHtCH*5i(OCHs)z Hs HzN CHtCHtN HCHICHtCHxSi(
OCHs)tHtN CON HCHtCHzCHzS
i(OCz)(s)sHEN CHgCHIN HCH
tCHtCHtSi(OCHs)sH! NCHtCH!
N1rCHICHIN)tCHt--CHtCHxSi
(OCHs)s Hs C! OCOCHt CH! NHCHtC
Ht CHt--3i(OCHs)s Hs Cz OCOCHt CHx N HCHt C
Ht N H-CHtCHtCHisi(OCHz)s
Hs Ct OCOCH! CHt N HCHt C
Ht N H--CHICH! NHCH1CH! NHC
H,--CHICHg5i(OCH3)! HsCOCOCHICHtNHCH*CHzNH-C
Htc H,x CHzsi(OCH2)3Hs Ct N CHsCHtCHzSi(OCH3)sHs Ct St(OCHs)s HsC CHtC]IzSi(OCHa)s HOCHzG Hz N CHtCHtCHiSi(OCHs )sHOCHl
CHt (HiCO)ssicHzcHtcHzNHcHt(H
sC0)ssi CHtCHsCHtN HCHt(H
s,,CzO)ssicHxcHtcHtH (HsCzO)zsic HtCHtCHtHsCN
HCHzCHzCHzSi(OCtHshHz N (
CHt CHt N H) z CHz CHt CH
z--5i(OCH3)3 HsCN HCON Hz ■ C5HaSi(OCH3)1 Furthermore, the above compound may be in a form in which the alkoxy group is substituted with a chlorine atom.

These compounds may be used alone or in combination.

As the amino-modified silicone oil, for example, one represented by the following general formula (1) can be preferably used.

General formula (1) (R21 represents an alkylene group, an aryl group, an aminoalkylene group, etc., Rll and RlJ each represent a hydrogen atom, a hydroxyl group, an alkyl group, an aryol group, etc., and x + y each represent (Represents an integer of 1 or more.) Furthermore, as the amino-modified silicone oil, those having an amino equivalent value within the range of 200 to 22,500 are preferable, and those within the range of 300 to 10,000 are particularly preferable.

When the amino equivalent value is too small, the effect of imparting positive chargeability by the inorganic fine particles is small, resulting in foggy and unclear images. On the other hand, when the amino equivalent value is too large, the 4R-free fine particles become carriers. It tends to transfer and adhere to particles, and the durability of the image forming agent may be reduced.

The amino-modified silicone oil preferably has a viscosity of 10 to 10,000 cps at 25°C, particularly preferably 20 to 3,500 cps. When the viscosity is too low, the stickiness of the inorganic fine particles becomes high, which may reduce the durability of the image forming agent.On the other hand, when the viscosity is too high, proper surface treatment becomes difficult, and as a result, the toner The positive chargeability of the developer may become unstable and the durability of the developer may decrease.

Examples of commercially available amino-modified silicone oils that can be preferably used include those listed in Table 1 below.

Table 1 Examples of the silicone varnish used to obtain the amino-modified silicone varnish include methyl silicone varnish, phenylmethyl silicone varnish, etc., and methyl silicone varnish is particularly preferred.

Methyl silicone varnish is T” shown by the following structural formula.
Unit: 1) It is a polymer consisting of 31 units, M'' units, and is a three-dimensional polymer containing a large amount of T'' units.

[T11 unit] CD” unit] 0
C1r.

CHi-5i -OCHz Si O-CM 31
unit] H3 CHz-SiO- Hs In addition, methyl silicone varnish or phenyl methyl silicone varnish is specifically, for example, represented by the following structural formula (1)
It is a substance that has the chemical structure shown below.

Structural formula (]) %Formula% ('R31 represents a methyl group or a phenyl group.)
In the silicone varnish mentioned above, the T3+ unit in particular is an effective unit for imparting good thermosetting properties and forming a three-dimensional network structure. The fine particles have a hard (and tough) film on their surface, and therefore have excellent impact resistance, moisture resistance, and mold release properties. Especially 3
It is preferably contained in a proportion of 0 to 80 mol%. This 3
3 If the proportion of T31 units is too small, the toner becomes soft and its tackiness increases, and the stability of moisture resistance, durability, and triboelectric charging properties may decrease.In particular, the cleaning performance of the toner decreases, and the toner Splattering occurs, resulting in uneven images,
Capri and the like may occur, and furthermore, the durability of the fixing device may be reduced. On the other hand, if the proportion of the T'' units is too large, the coating layer formed on the surface of the inorganic fine particles becomes non-uniform, and the stability and durability of triboelectric charging properties may decrease.

Further, such silicone varnish has a hydroxyl group at the end or side chain of its molecular chain, and is cured by dehydration condensation of this hydroxyl group.

Examples of hardening accelerators that can be used to accelerate this hardening reaction include fatty acid salts such as zinc, lead, cobalt, and tin; amines such as triethanolamine and butylamine; and the like. Among these, amines can be particularly preferably used.

In order to make the silicone varnish as described above into an amino-modified silicone varnish, some of the methyl groups or phenyl groups present in the T'' units, D!' units, and M31 units must be replaced with amino group-containing groups. Examples of the amino group-containing group that may be substituted include those represented by the following structural formula.

CHt G Hz N Ht -CH! (CH rich)g-NHt-G Hz(CHi)x-NH-(CHt)+-N
Hz+CHt-NHt The silicone rubber used to obtain the above-mentioned amino-modified silicone rubber is, for example, a long-chain polymer consisting only of D" units represented by the following structural formula, and has a viscosity of, for example, 10' at a temperature of 25°C. ~10" cps and an average molecular weight of, for example, 10' to 10" can be preferably used. Particularly, those with a viscosity of 10' to 1
0" cps and an average molecular weight of 10' to 10' are preferable. If the viscosity is too low or the average molecular weight is too small, durability and moisture resistance may decrease; on the other hand, if the viscosity is too high or When the average molecular weight is too large, it becomes difficult to uniformly treat the surface, and as a result, triboelectric charging properties become unstable, which tends to result in foggy and unclear images, and durability and moisture resistance may deteriorate.

(D" unit) -0-3i-0- 84 tatami (R41 and R4t each represent an alkyl group such as a methyl group or an ethyl group, an aromatic group such as a phenyl group, a polyether, etc.) R41 and R4t are preferably a methyl group or a phenyl group, particularly preferably a methyl group, and in order to give the silicone rubber a crosslinked structure, together with the D" unit shown by the structural formula below, It is preferable to copolymerize using a small amount of D4'' units represented by the formula.

(D4! unit) (D” unit) CH3CH
s j By making the silicone rubber have a cross-linked structure in this way, the inorganic fine particles whose surfaces have been treated with the silicone rubber have a hard and tough film on their surface, and therefore have high impact resistance and moisture resistance. , it has excellent mold releasability.

In addition, such silicone rubber preferably has a hydroxyl group at the end of the molecular chain or at the side chain, and curing is accelerated by dehydration condensation of the hydroxyl group, and the hydroxyl group is combined with the functional group on the surface of the inorganic fine particles. It becomes possible to form a film through reaction and strong chemical bonds. Known vulcanizing agents can be used to accelerate this curing reaction. Specifically, for example, benzoyl peroxide, bis-2,
Organic peroxides such as 4-dichlorobenzoyl peroxide, di-t-butyl peroxide, and dicumyl peroxide can be preferably used.

In addition, in order to make the silicone rubber as described above into an amino-modified silicone rubber, R41 and R of the D'' unit must be
Examples of the amino group-containing group in which a part of 4= may be substituted with an amino group-containing group include, but are not limited to, those represented by the following structural formula.

CHz CHx N Hz CHz(CHz)z-NHz -CHg(CHz)z NH(CHth NHzThe silicone resin used to obtain the amino-modified silicone resin has TSI units represented by the following structural formula, [
)51 units, Dsi units, and M'' units, and unlike silicone oil, it is a polymer containing a large amount of T'' units.

(T S 1 unit) CD” unit] (M
% 1 unit) CD52 unit]ll R55CH-CHx (RSI, Rst, R83,RSI, RSS
, 8% represents an organic group such as an alkyl group such as a methyl group or an ethyl group, or an aromatic group such as a phenyl group) Such silicone resins have many branches and are formed by crosslinking. It has hard properties because it has a very large number of fine networks, and the above T'' unit is an effective unit for creating a crosslinked structure, as well as an effective unit for forming a cyclic structure within the molecule. Therefore, silicone resin has both tough and flexible properties.In addition, silicone resin has
Since a considerable amount of silanol groups with OH groups that exist freely without forming siloxane bonds remain, these silanol groups may react with functional groups present on the surface of the inorganic fine particles or form siloxane bonds during the curing stage. As a result, the silicone resin has stronger properties.

Therefore, inorganic fine particles whose surfaces have been treated with such silicone resin have a tough yet flexible film on their surfaces, and therefore have excellent impact resistance, moisture resistance, and mold release properties. .

In addition, in order to make the silicone resin as described above into an amino-modified silicone resin, the T'' unit, the ps+ unit, the M
``Organic groups present in the unit (RSI).

R'', R'', R'', RSI, RSth) may be partially substituted with a group having 7mi/group. Examples of the group having an amino group include those shown in the following structural formula. can.

CHt G Hz -N Hz CHz (CHz) * NHt CHz (CHz) x N H (CHz)s N H
! +cHtNH! Inorganic fine particles whose surfaces are treated with the above compounds include, for example, silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, chromium oxide,
Cerium oxide, antimony dioxide, zirconium oxide,
Fine particles such as silicon carbide can be mentioned. The average particle size of the primary particles (particles separated into individual unit particles) of such inorganic fine particles is preferably within the range of 3 str to 2 n.

In particular, silica particles can be preferably used as the inorganic particles. Silica fine particles are 5t-0-Si
Fine particles having a bond may be produced by either a dry method or a wet method, but those produced by a dry method are preferable, and in particular, silica fine particles produced by vapor phase oxidation of a silicon halide compound. It is preferable that In addition, as silica fine particles, silicon dioxide (
silica), aluminum silicate, sodium silicate, calcium silicate, potassium silicate, zinc silicate,
Although fine particles made of silicate such as magnesium silicate may be used, those containing 85% by weight or more of SiO□ are preferable.

Known techniques can be used to treat the surface of the inorganic fine particles with the above compounds, and specifically, for example, after dispersing the inorganic fine particles in a solution in which the above compounds are dissolved in a solvent. , removing the solvent by filtration or spray drying, and then curing by heating, or spraying a solution of the above compound in a solvent onto inorganic fine particles using a fluidized bed device, and then drying by heating. A method of curing the film by removing the solvent by removing the solvent can be used.

The particle size of the positively charged inorganic fine particles whose surface has been treated with the above-mentioned compound obtained in this way is such that the average particle size of the primary particles is within the range of 31p to 2n1, particularly 5sp to 500mm. It is preferable that

In addition, the specific surface area according to the BET method is 20 to 500 m"
7 g is preferable. If the average particle size is too small or the specific surface area is too large, for example, when cleaning using a blade type cleaning device, inorganic fine particles easily slip through and cleaning defects occur. There is. On the other hand, when the average particle diameter is too large or the specific surface area is too small, the fluidity of the developer decreases, resulting in poor developability, which may result in a decrease in image density or the occurrence of image unevenness.

The positively chargeable inorganic fine particles are added to and mixed with the toner particles from the outside so that they are attached or implanted onto the surface of the toner particles, and a carrier is further mixed therein.

The positively charged state I! The content ratio of fine particles is 0.1 of the toner.
It is preferably from 5% by weight, particularly preferably from 0.1 to 2% by weight. When the content ratio of the positively chargeable inorganic fine particles is too small, the fluidity of the developer may decrease, resulting in poor triboelectric charging properties of the toner and imparting an appropriate amount of positive charge to the toner. This may cause capri or image unevenness to occur. Furthermore, when the content ratio is excessive, some of the positively chargeable inorganic particles may exist in a free state from the toner particles, and as a result, the free positively chargeable inorganic particles may adhere to and transfer to the carrier particles. , or the inner wall of the developing device,
It adheres and accumulates on the developing sleeve, regulating blade, etc., and eventually the toner's triboelectric charging properties become poor, making it difficult to apply an appropriate amount of positive charge to the toner, resulting in fogging and a decrease in image density. There are cases where

The toner used in the present invention is a toner containing a nigrosine dye, and is basically a particle powder composed of a binder containing a nigrosine dye, a colorant, and other additives. , the average particle size is usually 5~
The thickness is preferably about 20μ. Further, as other additives, for example, a fixing property improving agent, a cleaning property improving agent, etc. can be used.

The content ratio of the nigrosine dye is 0.01% of the toner.
It is preferable that the weight is 10% to 10%, particularly preferably 0
．． It is 1 to 5% by weight. If the content ratio is too small, the positive chargeability of the toner may decrease, while if the content ratio is too high, the nigrosine dye may transfer and adhere to the carrier particles, reducing the durability of the carrier. be.

The nigrosine dye is a general term for alcohol-soluble nigrosine dyes and basic nigrosine derivatives, and is used to impart a positive triboelectric charge to the toner when the carrier and toner are triboelectrically charged.

Specific examples of such nigrosine dyes include those shown below. In addition, it is not limited to these.

"Nigrosine J (manufactured by Ikeda Chemical Co., Ltd.)" Orient Spirit Blank Knee
Bee (Orient 5spirit Black
AB) J (manufactured by Orient Chemical Co., Ltd.) “Orient Spirit Bra 7ri Varnish Bee
(Orient 5spirit Black SR)
J (manufactured by Orient Chemical Co., Ltd.) “Spirit Black”
m850 j (manufactured by Sumima Kagaku Co., Ltd.) “Spirit Black”
m900 J (Sumitomo Chemical Company!!!ri “Spirit Black)
t'h920 J (manufactured by Sumima Kagaku Co., Ltd.) "Spirit Black"
h&x980 J (manufactured by Sumima Kagaku Co., Ltd.) “Nigrosine B
a5e N) J (National Aniline Diversion Ali-Chemical & Gui Corporation (National Aniline Div A1)
1iee Chemical & Dye Carp) [Nigrosin Base N.B.
eBase NB) J (Williams LTD.
Nigrosin-based G.B. (manufactured by )
eBase GB) J (Farbenfabriken Bayer Akchengesellschaft)
Nigrosin Base LK (manufactured by A, G, )
eBa5e LK) J (Badishe Aniline &5o
da Fabrik A.

Nigrosin Base E
t-ne Ba5e EX) J (manufactured by Orient Chemical Co., Ltd.) [Nigrosin Base Varnish O
eBase 5o)J (manufactured by Orient Kagaku Co., Ltd.) The binder for the toner is not particularly limited, but for example, a styrene-acrylic copolymer can be preferably used. This styrene-acrylic copolymer is basically a copolymer obtained from a styrene monomer and an acrylic monomer, and in particular, a styrene monomer, acrylic acid or its ester, and Copolymers obtained by polymerization with/or methacrylic acid or esters thereof can be preferably used. The styrene component can impart suitable release properties to the toner and improve off-cent resistance, and can also harden the toner and create a suitable positive triboelectric charge due to friction with the carrier. It is possible to obtain clear images with good image formation properties and transfer properties. Acrylic acid or its ester and/or methacrylic acid and its ester component can impart good fixing properties to the toner and form an image with excellent fixing strength.

In the styrene-acrylic copolymer, the styrene component is preferably contained in an amount of 60 to 90% by weight of the copolymer, while the acrylic component is contained in an amount of 40 to 10% by weight of the copolymer. It is preferably contained in a proportion of % by weight. When the proportion of the styrene component is too small and the proportion of the acrylic component is too large, the copolymer constituting the toner tends to transfer and adhere to the carrier particles, which impairs the properties of the carrier and reduces the durability of the developer. It may decrease. On the other hand, if the proportion of the styrene component is too large and the proportion of the acrylic component is too small, the fixing performance may be reduced.

The styrene-acrylic copolymer has a weight average molecular weight of 60,000 to 500,000, a number average molecular weight Mn of 1,000 to 30,000, and a ratio M of these.
Those having a w/Mn value within the range of 5.0 to 40 can be preferably used. By using a toner within such a preferable range, a toner with excellent anti-offset properties and fixing properties can be obtained. On the other hand, when the values of weight average molecular weight M-, number average molecular weight Mn, and ratio Mll/MTI are outside the above ranges, anti-offset properties and fixing properties may deteriorate.

Further, as the styrene-acrylic copolymer, one having a glass transition point Tg within the range of 45 to 70°C can be preferably used. If the glass transition point Tg is too low, the toner's fluidity may be reduced due to increased tackiness, while if the glass transition point Tg is too large, the fixing performance may be reduced.

Specific examples of styrenic monomers that can be used to obtain the styrene-acrylic copolymer include:
For example, styrene, 0-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-
Ethylstyrene, 214-dimethylstyrene, p-n-
Butylstyrene, p-tert-butylstyrene, p
-n-hexylstyrene, p-n-octylstyrene,
p-n-nonylstyrene, p-n-decylstyrene, p
-n-dodecylstyrene, p-methoxystyrene, p-
Examples include phenylstyrene, p-chlorostyrene, and 3,4-dichlorostyrene. These monomers may be used alone or in combination.

Furthermore, examples of the acrylic component that can be used to obtain the styrene-acrylic copolymer include acrylic acid, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, M2-chloroethyl acrylate, phenyl acrylate, methyl α-chloroacrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate , propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, methacrylate α-methylene aliphatic monocarboxylic acid esters such as diethylaminoethyl acid; acrylic acid or methacrylic acid derivatives; and others. These monomers may be used alone or in combination.

In addition, the styrene-acrylic copolymer includes other components such as vinyl esters such as vinyl acetate, vinyl butyrate, and vinyl benzoate; vinyl methyl ether;
Vinyl ethers such as vinyl ethyl ether; vinyl ketones such as vinyl methyl ketone; dienes such as butadiene and isoprene; unsaturated carboxylic acids such as maleile acid and fumaric acid; and the like may be contained as structural units.

The method for producing the styrene-acrylic copolymer is not particularly limited, and various methods can be used.

Specifically, for example, a solution polymerization method, a suspension polymerization method, an emulsion polymerization method, etc. can be used.

Examples of the colorant contained in the toner used in the present invention include carbon black, phthalocyanine blue, benzidine yellow, nigrosine dye, aniline blue, calco oil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, and methylene blue chloride. Dyes and pigments such as , malachite green offsalate, lamp black, and rose bengal can be used. These substances may be used alone or in combination, and the content of the colorant is usually preferably 1 to 15% by weight of the toner.

In addition, examples of the fixability improver include polyolefin,
Fatty acid metal salts, fatty acid esters and fatty acid ester waxes, higher fatty acids, higher alcohols, liquid or solid paraffin waxes, amide waxes, polyhydric alcohol esters, silicone varnishes, aliphatic fluorocarbons, and the like can be used.

Further, as the cleaning property improving side, for example, fatty acid metal salts such as zinc stearate, calcium stearate, and stearic acid, and polymer particles such as methyl methacrylate particles and styrene particles can be used.

In the present invention, the glass transition point Tg is the extension line of the baseline below the glass transition point when measured using a differential scanning calorimetry needle "low-temperature DSCJ (manufactured by Rigaku Denki) at a heating rate of 10°C/sin." This is the temperature at the intersection of the curve and the tangent line showing the maximum slope from the rising edge of the peak to the top of the peak.

In addition, the values of weight average molecular weight M- and number average molecular weight Mn can be determined by various methods, and there are slight differences depending on the measurement method, but in the present invention, the values determined by the following measurement method are as follows: It is defined as

That is, the weight average molecular weight Mw, number average molecular weight Mn, and peak molecular weight are measured by gel permeation chromatography (CGPC') under the conditions described below. At a temperature of 40°C, the solvent (tetrahydrofuran) was flowed at a flow rate of 1.2 d/min, and the concentration was 0.2 g/20
- 3I using the tetrahydrofuran sample solution as the sample weight
When measuring the molecular weight of a sample by injecting 1 g, the molecular weight of the sample should be within the range where the logarithm of the molecular weight and the count number of the calibration curve prepared using several types of monodisperse polystyrene standard samples are linear. Select the measurement conditions to be measured.

The reliability of the measurement results is based on the NB5706 boristyrene standard sample (weight average molecular weight M
w=28.8X10', number average molecule IMF+=13.7
XIO', Mw/Mn=2.11) ratio Mw/Mn
Confirm that the value of is 2.11±0.10.

Note that any GPCO column may be used as long as it satisfies the above conditions. Specifically, for example, TSK-GEL, GM)1. (manufactured by Toyo Soda d), etc. can be used.

Next, the electrostatic image developing method of the present invention will be explained.

In the electrostatic image developing method of the present invention, a negative electrostatic latent image formed on the surface of an organic photoreceptor is formed using a specific carrier as described above, a specific toner as described above, and the positively charged inorganic fine particles. A toner image is formed by developing with a specific electrostatic image developer containing.

The organic photoreceptor is usually constructed by laminating a photosensitive layer containing a photoconductive semiconductor made of an organic compound on a conductive support. The photosensitive layer may be composed only of a photoconductive semiconductor made of an organic compound, or may be composed of the photoconductive semiconductor dispersed in a binder made of a resin.

The photosensitive layer includes a carrier generation layer containing a carrier generation substance that absorbs visible light and generates charged carriers, and a carrier generation layer that transports either or both of positive and negative carriers generated in this carrier generation layer. It is preferable to use a so-called functionally separated type photosensitive layer configured by combining a carrier transport layer containing a carrier transport substance. In this way, by assigning the two basic functions necessary for the photosensitive layer, namely carrier generation and carrier transport, to separate layers, the range of materials that can be used in the composition of the photosensitive layer is widened, and each It becomes possible to independently select the substance or material system that optimally performs the function.
In addition, by doing so, it is possible to achieve excellent characteristics required in the image forming process, such as high surface potential when charged, high charge retention capacity, high photosensitivity, and high stability during repeated use. It becomes possible to construct an organic photoreceptor having specific characteristics.

As carrier-generating substances in the photosensitive layer, for example, anthrone pigments, perylene derivatives, phthalocyanine pigments, azo dyes, indigoid dyes, etc. can be used. Examples of carrier transport substances include carbazole derivatives, oxadiazole derivatives, triarylamine derivatives, polyarylalkane derivatives, hydrazone derivatives, pyrazoline derivatives, stilbene derivatives,
Styryl triarylamine derivatives and the like can be used. It is preferable that the carrier generation layer has a thickness of usually 0.01 to 2p, and the carrier transport layer has a thickness of usually 1 to 30n.

When forming a photosensitive layer by dispersing a photoconductive semiconductor made of an organic compound in a binder made of a resin, examples of the resin that can be used as the binder include polyethylene, polypropylene, acrylic resin, methacrylic resin, chloride resin, etc. Addition polymer resins, polyaddition resins, polycondensation resins such as vinyl resin, vinyl acetate resin, epoxy resin, polyurethane resin, phenol resin, polyester resin, acrylic resin, polycarbonate resin, silicone resin, melamine resin, and these Copolymer resins containing two or more of the repeating units of the resin, such as vinyl chloride-vinyl acetate copolymer resins, vinyl chloride-vinyl acetate-maleic anhydride copolymer resins, styrene-acrylic copolymer resins, etc. Examples include insulating resins, and polymeric organic semiconductors such as poly-N-vinylcarbazole.

In the organic photoreceptor, examples of the conductive support include aluminum, nickel, copper, zinc, palladium, S.
A metal sheet made of indium, tin, platinum, gold, stainless steel, steel, brass, etc. can be used.

The specific structure of the organic photoreceptor is not particularly limited, and various structures can be adopted. Further, an organic photoreceptor whose surface potential when charged is, for example, -400 to -1000 V can be particularly preferably used.

FIG. 1 is an explanatory diagram showing an example of a developing device that can be suitably used to carry out the electrostatic image developing method of the present invention.

Reference numeral 10 denotes an organic photoreceptor, which has the shape of a rotating drum that is rotated in the direction of arrow The photosensitive layer 10B containing is laminated. A charger and an exposure optical system (not shown) are arranged upstream of the development space 24, and the charger first sets the surface of the organic photoreceptor 10 to be developed at a temperature of -400 to -1, for example.
charged to a constant negative potential within the range of 000v,
Next, an exposure optical system (not shown) projects an optical image of the original onto the developed surface of the organic photoreceptor 10, and an electrostatic latent image corresponding to the original is formed on the developed surface, and this electrostatic latent image is moved to the developing space 24, and the electrostatic latent image is developed in the developing space 24.

11 is a developing sleeve, and this developing sleeve 11 is
The developing sleeve 11 has a rotating drum shape made of a non-magnetic material such as aluminum, and a magnet 2 is disposed inside the developing sleeve 11. This magnet body 12 consists of a plurality of N and S magnetic poles arranged along the circumference of the developing sleeve 11. The developing sleeve 11 and the magnet 12 cause the developing wIlIl carrier to be an oxygen carrier, and in a specific example, the developing sleeve 11 is aligned in the direction of arrow Y, that is, in the direction of movement of the organic photoreceptor 10 in the developing space 24. The magnets 12 are rotated to move in the same direction, and the magnets 12 are fixed, for example. In the present invention, the rotation direction of the developing sleeve 11 is not particularly limited, and the magnet body 12 may be rotated in an appropriate direction.

The N and S poles constituting the magnet body 12 are magnetized so that the magnetic flux density on the surface of the developing sleeve is usually about 500 to 1500 Gauss, and the magnetic force causes the developer 22 to be applied to the surface of the developing sleeve 11. A developer layer (magnetic brush) 23 having particles standing up like a brush is formed.

Reference numeral 13 denotes a regulating blade, which is made of a magnetic or non-magnetic material and is used to regulate the height and amount of the developer 123 reaching the developing space 24. Reference numeral 14 denotes a cleaning blade, and this cleaning blade 14 is used to scrape off and remove the developer remaining on the surface of the developing sleeve 11 after development.

The surface of the developing sleeve 11 that has been cleaned by the cleaning blade 14 comes into contact with the developer 22 again in the developer reservoir 15 to form a new magnetic brush on the surface, and after this magnetic brush is controlled by the regulation blade 13, development is performed. It is transported to the space 24.

15 is a developer reservoir; 16 is a stirring screw; in the developer reservoir 15, toner and carrier constituting the developer 22 are mixed and dispersed by the stirring screw 16;
This makes it possible to make the toner concentration uniform. Also,
The carrier of the developer 22 is used repeatedly, while the toner is consumed each time development is performed. Therefore, new toner in the toner hopper 17 is transferred to the developer reservoir 15 by the supply roller 18 having a recessed portion on its surface. will be replenished accordingly.

Reference numeral 19 denotes a bias power supply, and 20 denotes a protective resistor, and the bias voltage necessary for development is applied to the developing sleeve 11 via the protective resistor 20 by this bias voltage a19. This bias voltage is preferably a DC voltage of about 50 to 500V, for example.

In developing an electrostatic latent image, it is preferable for the tip of the magnetic brush to make shallow contact with the surface of the organic photoreceptor IO in order to achieve uniform development. The distance (Hcut) between the organic photoreceptor 10 and the developing sleeve 11 in the developing space 24 is
The gap (D sd) is preferably about 0.8 times the gap (D sd) between the
．． It is preferable to set the gap to 0 fins.If the gap (Dsd) is too large, developing performance may deteriorate or toner scattering may occur.On the other hand, if the gap (Dsd) is too small, toner scattering or toner scattering may occur. Carrier adhesion to the image area may occur, making the image unclear.

In the apparatus configured as described above, when the developing sleeve 11 rotates, the magnitude and direction of the magnetic field on its surface sequentially change, so that the carrier particles in the magnetic brush formed on the surface of the developing sleeve 11 rotate and vibrate. At the same time, the toner particles are moved to the developing space 24 following the rotational movement of the developing sleeve 11, and as a result, the toner particles attached to the surface of the carrier particles by electrostatic force are conveyed to the developing space 24.

Next, an image forming method using the developer and developing method of the present invention will be described.

First, a negative electrostatic latent image is formed on the surface of the organic photoreceptor (latent image forming step), this electrostatic latent image is developed with the specific developer (developing step), and the toner image obtained by development is A fixed visible image is formed by electrostatically transferring the toner image onto a transfer material (transfer step) and fixing the toner image by contact heating the toner image on the transfer material with a heat roller (fixing step). The developer remaining on the surface of the photoreceptor is cleaned using a cleaning blade (cleaning step) to restore the surface of the organic photoreceptor to its original clean state.

In the latent image forming step, the surface of the organic photoreceptor is charged to a uniform negative potential (charging step), and then a light image of the document is projected onto the charged surface of the organic photoreceptor (exposure step).
As a result, an electrostatic latent image made of electrostatic charges is formed on the surface of the organic photoreceptor.

Specifically, in the charging step, the entire image forming area on the surface of the organic photoreceptor is charged to a potential of, for example, about -400 to -1000V using, for example, a corona charger, and in the exposure step, the charging An exposure optical system comprising, for example, a light source, a reflecting mirror, and a lens produces a reflected light image or a transmitted light image of the document on the surface of the organic photoreceptor whose surface is charged to a uniform negative potential during the process. The image is formed, thereby forming a negative static T4 latent image corresponding to the original on the surface of the organic photoreceptor.

In the transfer step, an electrostatic transfer method can be preferably used. Specifically, for example, a transfer device that generates an alternating current corona discharge is placed so as to face the organic photoreceptor through the transfer material, and the alternating current corona discharge is applied to the transfer material from the back side of the organic photoreceptor. The toner carried on the surface is transferred to the surface of the transfer material.

In the cleaning step, a cleaning blade is used. This cleaning blade is preferably made of urethane rubber, for example, and in this case, cleaning performance and durability are improved. The cleaning blade is usually placed in a state in which it is lightly and elastically pressed against the surface of the photoreceptor, and cleaning is accomplished by scraping off toner remaining on the surface of the photoreceptor.

In order to facilitate cleaning, it is preferable to add a static elimination process to neutralize the surface of the organic photoreceptor before the cleaning process. This static elimination step can be performed, for example, by a static eliminator that generates an AC one-cona discharge.

In the fixing step, it is preferable to perform fixing by a contact heating method using a heat roller fixing device having a heat roller. Further, as the heat roller, one whose surface is coated with a fluororesin or a silicone resin can be preferably used. A heat roller fixing device usually includes a heat roller, a backup roller placed in opposition to the heat roller, and a heat source for heating the heat roller.
Alternatively, a cleaning roller may be further arranged in opposition to the heat roller. Specifically, as a heat roller,
For example, a core material made of a metal such as iron or aluminum and a coating layer made of a fluororesin such as Teflon (polytetrafluoroethylene manufactured by DuPont) or a silicone resin can be preferably used. . Moreover, as the bank up roller, one constructed by providing a coating layer made of silicone rubber or the like on the surface of a metal core material can be preferably used.

FIG. 2 is an explanatory diagram showing an example of an image forming apparatus that can be suitably used to form an image by applying the developer and developing method of the present invention.

30 is a cabinet, and on the top of this cabinet 30 is a manuscript 31! A glass original mounting table 32 for placing 32 originals, and a platen cover 33 for covering the original 31 are provided. Transfer paper 4 is placed on one end of the cabinet 30.
A paper feed tray 41 into which 0 is set is provided, and a paper discharge tray 42 is provided at the other end. 43 and 44 are paper feed rollers, and 45 is a paper discharge roller.

Reference numeral 50 denotes an a-containing photoreceptor for forming a negative electrostatic latent image, and this organic photoreceptor 50 has a rotating drum shape. Around the organic photoreceptor 50, from the upstream side to the downstream side in the rotational direction, a corona charger 51, an exposure optical system 52, a magnetic brush developer 53, and an electrostatic transfer device 54 are arranged.
, a separator 55, and a blade type cleaning device 56 are arranged.

The exposure optical system 52 includes a first mirror unit 63 consisting of a light source 61 and a first mirror 62;
A second mirror unit 6 consisting of a pair of mirrors arranged in order along the optical path from the filter 3 to the organic photoreceptor 50.
4, a lens 65, a mirror 66, and a groic mirror 67. The first mirror uni, Toro 3, is
A second mirror unit/1-64 is provided below the document placing table 32 so as to be movable so as to be scanned with respect to the document placing table 32, and the second mirror unit/1-64 maintains a constant optical path length from the document scanning point to the organic photoreceptor 50. The first mirror unit 63 is provided so as to be movable in accordance with the moving speed of the first mirror unit 63 so that the first mirror unit 63 can move at a speed corresponding to that of the first mirror unit 63. When the original 31 placed on the original holding table 32 is illuminated with slit-shaped illumination light scanned by the exposure optical system 52, the slit-shaped reflected light images of the original 31 sequentially formed by scanning are rotated. The images are sequentially projected onto the developing surface of the moving organic photoreceptor 50.

Reference numeral 70 denotes a contact heating type heat roller fixing device. 72.

In the above apparatus, the surface to be developed of the organic photoreceptor 50 is charged to a uniform negative potential by the corona charger 51, and then imagewise exposed by the exposure optical system 52, so that the surface of the organic photoreceptor 50 is
A negative electrostatic latent image corresponding to the original is formed on the surface to be developed. This negative electrostatic latent image is then developed by the magnetic brush developing device 53 to form a toner image corresponding to the original.

The toner image on the organic photoreceptor 50 is electrostatically transferred onto the transfer paper 40 by the electrostatic transfer device 54, and the toner image on the transfer paper 40 is heated and fixed by the heat roller fixing device 70 to form a fixed image. On the other hand, the surface of the organic photoreceptor 50 that has passed through the electrostatic transfer device 54 is rubbed by a blade-type cleaning device 56, and the toner remaining on the surface is scraped off, resulting in the original clean surface. In addition to that,
It will be subjected to the charging process by the corona charger 51 again.

According to the above-described image forming means, the positive chargeable inorganic fine particles impart suitable mold releasability to the developer, so that the physical adhesion force to the surface of the organic photoreceptor is small, and therefore, in the transfer process. Good transfer can be performed using an electrostatic transfer means, and it is possible to reliably form a clear image with high image density and no image unevenness.

In addition, since the transferability of the developer is good, only a small amount of developer remains on the organic photoreceptor after the transfer process.
Therefore, in the cleaning process, it is easy to clean the remaining developer, and since the developer has suitable release properties due to the presence of positively charged inorganic particles, the developer is not easily removed from the organic photoreceptor. The adhesive force is small, and as a result, the developer can be easily cleaned using a cleaning blade.

In addition, since the cleaning properties of the developer are good, it is possible to achieve good cleaning with a small pressure contact force of the cleaning blade against the organic photoreceptor, and therefore the surface of the organic photoreceptor is abraded by the cleaning blade. This prevents the characteristics of the organic photoreceptor from deteriorating early, and the service life of the organic photoreceptor can be significantly extended.

In addition, in the fixing step, positively charged inorganic fine particles are present between the surface of the molten developer and the hot roller, and the positively charged inorganic fine particles provide a mold release effect, allowing the hot roller of the developer to Transfer and adhesion to the heat roller is prevented, and developer is prevented from accumulating in the minute grooves of the heat roller. As a result, image staining caused by the offset phenomenon can be prevented.

[Specific examples]

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

(Manufacture of carrier) (1) Carrier CI (for the present invention) 8 parts by weight of silicone varnish rSR-2101J (manufactured by Toray Silicone Co., Ltd.) was mixed into spherical copper-zinc particles with an average particle size of 100 nm using a fluidized bed device. Ferrite particles (
100 parts by weight of Nippon Tetsuko Co., Ltd.) was spray coated, further heat-treated at 200°C for 5 hours to sinter, and then the aggregates were sieved to form a coating layer made of sintered silicone varnish. A carrier was manufactured. This is called “Career CIJ.”

This carrier C1 has an average particle size of 1Q2n and a ratio of the major axis to the minor axis (major axis/minor axis) of 1.05.

(2) Carrier C2 (for the present invention) In the production of carrier CI, silicone rubber rsH-
2047J (manufactured by Le Silicone), 0.05 parts by weight of benzoyl peroxide, and an average particle size of 88 nm.
Spherical copper-zinc ferrite particles (manufactured by Nippon Tetsuko Co., Ltd.) 10
A carrier having a coating layer made of a sintered silicone rubber was produced by the same treatment except that 0 part by weight was used. This is referred to as [Carrier C2J. This carrier C2 has an average particle diameter of 90 μm and a ratio of major axis to minor axis (major axis/breadth axis) of 1.04.

(3) Carrier C3 (for the present invention) Spherical copper particles with an average particle size of 50μ are dissolved in a coating solution prepared by dissolving 2 parts by weight of silicone resin rsR-2400J (manufactured by Le Silicone Co., Ltd.) in 50 parts by weight of xylene. - Zinc ferrite particles (manufactured by Nippon Tetsuko Co., Ltd.) After seeding with 100 parts by weight, the solvent was heated to volatilize and remove the xylene, and further heat treated at 200°C for 5 hours to sinter, and then the aggregates were sieved. A carrier having a coating layer made of a sintered silicone resin was produced. This is called "Carrier C3J. This carrier C3 has an average particle size of 52
μ, the ratio of the major axis to the minor axis (major axis/minor axis) is 1.03.

(4) Carrier C4 (for the present invention) In the production of carrier C3, silicone varnish rKR
-216J (manufactured by Shin-Etsu Chemical Co., Ltd.) 1.0 part by weight was used, but the same treatment was carried out to produce a carrier having a coating layer made of a sintered silicone varnish. This is called “Carrier C4J.

This carrier C4 has an average particle size of 51. n, and the ratio of the major axis to the minor axis (major axis/minor axis) is 1.02.

(5) Carrier C5 (for the present invention) A coating liquid was prepared by dissolving 15 g of the exemplary polymer (1) in a mixed solvent of acetone and methyl ethyl ketone (mixed volume ratio = 1:1) to prepare a coating liquid. The solution was coated on 1 kg of magnetic particles made of spherical copper-zinc ferrite particles using a fluidized bed device, heat-treated at 200°C for 5 hours, and then the aggregates were sieved to determine the average thickness. A carrier was produced with a coating layer having a length of approximately 2n. This is called "Carrier C5J. This carrier C5 has an average particle size of 102n and a ratio of the major axis to the minor axis (major axis / minor axis)
is 1.06.

(6) Carrier C6 (for the present invention) In the production of carrier C5, exemplified polymer (3) was used instead of exemplified polymer (1), and spherical copper-zinc ferrite particles with different average particle diameters were used as magnetic particles. A carrier having a coating layer having an average thickness of about 2 fl was produced by the same treatment except that a carrier was used. This is referred to as "Carrier C6J. This carrier C6 has an average particle size of 81n and a ratio of major axis to minor axis (major axis/minor axis) of 1.04.

(7) Carrier C7 (for the present invention) In the production of carrier C5, exemplified polymer (5) was used instead of exemplified polymer (1), and spherical copper-zinc ferrite particles with different average particle diameters were used as magnetic particles. A carrier having a coating layer having an average thickness of about 2n was produced by the same treatment except that . This is referred to as "Carrier C7J. This carrier C7 has an average particle diameter of 5 In and a ratio of major axis to minor axis (major axis/breadth axis) of 1.07.

(8) Carrier C8 (for the present invention) Vinylidene fluoride-ethylene tetrafluoride copolymer rVT-
100J (copolymerization molar ratio -80:20, intrinsic viscosity -0.95aj/g, manufactured by Daikin Industries, Ltd.) and 6 g of methyl methacrylate copolymer "Acrivet MFj (manufactured by Mitsubishi Rayon Co., Ltd.) were mixed with acetone and methacrylate. .

Mixed solvent with ethyl ketone (mixed volume ratio = 1:1)
500 y to prepare a coating liquid, this coating liquid was applied to 1 kg of magnetic particles made of spherical copper-zinc ferrite particles using a fluidized bed device, and further heated at 200°C for 5 hours. After heat treatment for a period of time, the agglomerate was then sieved to produce a carrier with a coating layer having an average thickness of about 2 microns. This is called [Carrier C8J]. This carrier C8 has an average particle diameter of 5 hn and a ratio of the major axis to the minor axis (major axis/minor axis) of 1.05.

(Manufacture of inorganic fine particles) (1) Inorganic fine particles AI (for the present invention) 100 parts by weight of silica fine particles "Aerosil 200J (manufactured by Nippon Aerosil Co., Ltd.) having an average particle diameter of 12 mp and a specific surface area of 200 m"/g were placed in a high-speed rotating mixer. and then 8 parts by weight of N-β (aminoethyl) T-aminopropyltrimethoxysilane rKBM 603J (manufactured by Shin-Etsu Chemical Co., Ltd.) and hexamethyldisilazane "5Z6079".
J (manufactured by Les Silicone Co., Ltd.) dissolved in 100 parts by weight of hexane was added dropwise to the above-mentioned high-speed rotating mixer to perform surface treatment, and then the contents of the mixer were poured into a flask. By heating under an inert gas atmosphere at a temperature of 100 to 150°C for 5 hours while stirring, the hexane solvent was removed and the reaction was proceeded until the average particle size of the primary particles was 12 mm x 2 B.
Positively chargeable inorganic fine particles with a specific surface area of 190 m''7g were produced by the ET method.These are referred to as inorganic fine particles AIJ.These inorganic fine particles A1 have a triboelectric charge amount of +50 to +20 (Ic) with the carrier CIA-08. /g, and in particular, the amount of frictional electrification with the carrier C1 is +64 m/g.

(2) Inorganic fine particles A2 (for the present invention) In the production of inorganic fine particles A1, the amine equivalent is 3500
．． Same procedure except that 10 parts by weight of amino-modified silicone oil rSF8417J (manufactured by Tou μ Silicone Co., Ltd.) having a viscosity of 1200 cps at 25°C and 8 parts by weight of hexamethyldisilazane rsZ6079J (manufactured by Tou μ Silicone Co., Ltd.) were used. The average particle diameter of the primary particles is 131μ, and the specific surface area by BET method is 18011μ.
g/g of positively charged inorganic fine particles were obtained. This is referred to as "inorganic fine particle A2J. This inorganic fine particle A2 is carrier C1
The amount of frictional charge with ~C8 is within the range of +50 to +200t/g, and especially the amount of frictional band Igl with carrier C1 is +7
It is 0m/g.

(3) Inorganic fine particles A3 (for the present invention) In the production of inorganic fine particles At, the average particle size is 1611I
, 100 parts by weight of silica fine particles "Aerosil 130J (manufactured by Nippon Aerosil Co., Ltd.) having a specific surface area of 130 m" and 7 g and 20 parts by weight of an amino-modified silicone varnish having a structural unit represented by the following structural formula were dissolved in 100 parts by weight of xylene. 1 was processed in the same manner except that a processing solution of
Positively charged inorganic fine particles with an average particle size of 161〃 and a specific surface area of 92 m''7g by BET method were obtained.
The inorganic fine particles are referred to as A3J.

The amount of triboelectric charge with carriers 01 to C8 of the mless fine particles A3 is within the range of +50 to +200 7 g, and especially the amount of triboelectricity with carrier C1 is +106 tIc/g.

(x, y, z are each integers greater than or equal to 1, and x: y
:z-1:4:5. ) (4) Inorganic fine particles A4 (for the present invention) In the production of inorganic fine particles AI, 100 parts by weight of silica fine particles "Aerosil 3QOJ (manufactured by Nippon Aerosil Co., Ltd.) having an average particle diameter of 7 mg and a specific surface area of 300 m"/g and the following The same treatment was carried out except that a treatment solution prepared by dissolving 25 parts by weight of an amino-modified silicone rubber having the structural unit represented by the structural formula and 0.2 parts by weight of benzoyl peroxide in 125 parts by weight of xylene was used. The average particle size of primary particles is 7
Positively chargeable inorganic fine particles with a specific surface area of 166 o+''/g by the BET method were obtained.These are referred to as inorganic fine particles A4J. +20 (within the range of Ic/g, especially the amount of frictional charge with carrier CI is +185jIc/g)
It is g.

(x, y, z are each integers greater than or equal to 1, and x: y
:z=7:11. ) (5) Inorganic fine particles A5 (for the present invention) As constituent units, the following D1 unit, the following D2 unit, the following A
D' unit, the following TI unit, and the molar ratio of these is 4.
A treatment liquid was prepared by dissolving an amino-modified silicone resin having a ratio of 5:0.5:1:4 and benzoyl peroxide in an amount of 0.5% by weight based on the amino-modified silicone resin in xylene.

CD' unit) CD family unit] CHs
CHx -O-3i-0--0-5t-0- I CH3C' H= CHt (T' unit) CA D' unit] OcHw I CHz GHz (CHz)tN
HzNext, silica fine particles "Aerosil 300J (manufactured by Nippon Aerosil Co., Ltd.) were placed in a mixer, and after spraying a treatment solution such that the amino-modified silicone resin was 20% by weight on the silica fine particles, these was placed in a flask, and the solvent xylene was removed at a temperature of 120°C for 5 hours while stirring, and the amino-modified silicone resin was subjected to a curing reaction. ``7 g of positively charged inorganic fine particles were obtained. This is referred to as "inorganic fine particle A5J. The amount of triboelectric charge of this inorganic fine particle A5 with carriers 01 to C8 is within the range of +50 to +200 C/H, and in particular, the amount of triboelectric charge with carrier C1 is +195〆/g. be.

(Manufacture of toner) (1) Toner Tl (for the present invention) Styrene-n-butyl acrylate-methyl methacrylate copolymer obtained by polymerization using benzoyl peroxide as an initiator (copolymerization weight composition ratio = 7 : 2 :
1. Weight average molecular weight Mw = 130.000, number average molecule i1 Mn -10,000, Mw/Mn = 13,
100 parts by weight of glass transition point Tg = 60°C) and 10 parts by weight of carbon black "Mogull LJ (manufactured by Cabot)"
parts by weight and 2 parts by weight of "Nigrosine Base Varnish O" (manufactured by Orient Chemical Co., Ltd.), and then thoroughly melted and kneaded using two rolls at 100 to 130°C, and the f&? e, coarsely pulverized with a hammer mill, further finely pulverized with a jet mill, and then classified to obtain particles with an average particle size of 11. On toner was obtained. This is referred to as "toner T1".

(2) Toners T2 to T4 (for the present invention) In the production of toner T1, "Nigrosine Base E.
Toners were prepared in the same manner except that "X" (manufactured by Orient Chemical Co., Ltd.), "Spirit Black Varnish Bee" (manufactured by Orient Chemical Co., Ltd.), and "Spirit Blank Knee Bee" (manufactured by Orient Chemical Co., Ltd.) were used. I got it. These are referred to as "toner T2J" to "toner T4J, respectively.

(3) Toners T5 to T7 (for the present invention) In the production of toner T1, the amounts of "Nigrosine Base Varnish O" were changed to 1.5 parts by weight, 2.5 parts by weight, and 3.0 parts by weight, respectively. Other than that, toner was obtained in the same manner. These are referred to as "toner T2J to toner T7J," respectively.

(4) Toner T8 (for the present invention) In the production of toner T1, “Nigrosine Base E.
A toner was obtained in the same manner except that 11 parts of 3.0j of "X" (manufactured by Orient Chemical Co., Ltd.) was used. This is referred to as [Toner T8J.

(5) Toner T9 (for comparison) A toner was obtained in the same manner as Toner T1 except that "Nigrosine Base Varnish O" was not used.

This is called "Toner T9J.

<Examples 1 to 8 and Comparative Example 1> In each of the Examples and Comparative Examples, carriers and toners having the combinations and blending amounts shown in Table 2 below and positive chargeability were used.
UR1! developer using am particles. Shita.

That is, first, positively chargeable inorganic fine particles are added to the toner from the outside, and these are mixed using a Henschel mixer, so that the positively chargeable inorganic fine particles are attached or implanted onto the surface of the toner particles and retained, and then these are transferred to the carrier. A developer was prepared by mixing.

The developers obtained in Examples 1 to 8 were each used as "Development side 1".
~ "Developer 8" and the developer obtained in Comparative Example 1 are referred to as "Comparative Developer 1."

Table 2 <Live-action test> (1) Test 1 (Live-action test under room temperature environmental conditions) A photoreceptor for forming a negative electrostatic latent image, a contact magnetic brush developer, and an alternating current corona discharge A corona transfer device that generates a
RTV" (manufactured by Shin-Etsu Chemical Co., Ltd.) An electrophotographic copying machine r U-Bix equipped with a heat roller fixing device made of a backup roller formed by the "RTV" (manufactured by Shin-Etsu Chemical Co., Ltd.) and a cleaning device having a cleaning blade made of urethane rubber.
1550MRJ (manufactured by Konishiroku Photo Industry Co., Ltd.) was used to continuously form copied images 10,000 times using each of the above developers under room temperature environmental conditions of 20°C and 40% relative humidity. A test was conducted and the following items were evaluated. In addition, the live-action test is 5
The test was carried out intermittently with a one-day rest period every 1,000 runs. The results are shown in Tables 3 and 4 below.

The above-mentioned organic photoreceptor has a photosensitive layer having a negatively charged 211 structure formed using an anthrone-based pigment as a carrier-generating substance and a carbazole derivative as a carrier-transporting substance, and a rotating drum-shaped aluminum conductive support. It is constructed by laminating layers on the body.

The surface potential ('highest potential) of the organic photoreceptor during charging is -700V, the gap (Dsd) between the photoreceptor and the developing sleeve in the developing space is 0.45m+, and the distance between the tip of the regulating blade and the developing sleeve. distance (Hcut)
is 0.42 mm, the magnet body is a fixed type, the magnetic flux density on the surface of the developing sleeve is 800 Gauss, and the bias voltage applied to the developing sleeve is -150 V in DC voltage.

■Fog “Sakura Densitometer” (manufactured by Konishiroku Photo Industry Co., Ltd.)
The determination was made by measuring the relative density of the white background portion of the original with a density of OoO to the copied image. Note that the white background reflection density was set to 0.0. In the evaluation, when the relative concentration is less than 0.01, it is defined as rOJ, and when it is 0.01 or more and less than 0.03, it is "rOJ".
Cases of 0.03 or more were marked as "x".

■Image density "Sakura densitometer" (manufactured by Konishiroku Photo Industry Co., Ltd.)
was used to measure the relative density of a white background portion with an original density of 0.0 with respect to a copied image. For evaluation, when the image density was 1.0 or more, rOJ was given, when it was 0.7 or more and less than 1.0, it was given "△", and when it was less than 0.7, it was given "x".

The 0-quality copied images were visually judged from five points: image missing, image unevenness, image blur, image fading, and sharpness. The evaluation was ``x'' if it was poor and had a practical problem, ``Δ'' if it was slightly defective but at a practical level, and ``○'' if it was good.

"Image missing" refers to a phenomenon in which part of an image is missing, "image unevenness" refers to a phenomenon in which differences in shading occur in an image, and "image blur" refers to a phenomenon in which the density in the peripheral areas of an image decreases. "Image fading" refers to a phenomenon in which band-like differences in shading appear in an image.

■Toner scattering Visually observe the inside of the copying machine and the copied image. If there is almost no toner scattering and it is in good condition, mark it as ``○.'' If the toner scattering is slightly noticeable but still at a practical level, mark it as ``Δ.''
”, and cases where a large amount of toner scattering was observed and there was a problem in practical use were rated “×”.

(2) Cleaning properties After repeated image formation, the surface of the photoreceptor was visually observed immediately after being cleaned with a cleaning blade, and judgment was made based on the presence or absence of deposits on the surface of the photoreceptor. The evaluation is: rOJ is good with almost no deposits observed, "Δ" is when deposits are slightly reduced but at a practical level, and "Δ" is when a lot of deposits are observed and there is a problem in practical use. I marked it with an “×”.

(2) Heat roller dirt The heat roller constituting the fixing device was visually observed and determined. The rating is "x" if there is a lot of heat roller dirt and it is a practical problem, "Δ" if the heat roller dirt is slightly noticeable but still at a practical level, and "Δ" if the heat roller dirt is mostly observed. If it is not possible to do so, it is marked as “○”.

(2) Test 2 (live-action test under high-temperature environmental conditions) A live-action test was conducted in the same manner, except that the environmental conditions were a high-temperature environment of 30°C and 80% relative humidity, and each of the above items was evaluated. . The results are shown in Table 5 below.

As can be understood from the results in Tables 3 to 5, developers 1 to 8 of the present invention have good toner triboelectric charging properties and fluidity, and therefore, in the developing process, magnetic brush A negative electrostatic latent image formed on an organic photoreceptor by a developing method can be developed well without toner scattering,
In the transfer process, electrostatic transfer means can perform transfer at a high transfer rate, and in the cleaning process, a cleaning blade with a simple structure can perform good cleaning, and in the fixing process, a heated roller The fixing device allows for good fixing without the occurrence of offset phenomena, and as a result, fogging,
It is possible to form a good image with clear image quality without image missing, image unevenness, image blur, or image fading, and with high image density.

Further, even in the initial stage of image formation, the triboelectric charging property has good rise characteristics, and an initial image of good image quality without fogging can be formed.

Further, even when performing the image forming process many times, the heat roller and backup roller in the heat roller fixing device do not get dirty, and the service life of the rollers is significantly extended.

Furthermore, good images can be stably formed many times even under high temperature environmental conditions.

On the other hand, according to Comparative Developer 1, since Toner T9 does not contain nigrosine dye, the triboelectric charging characteristics are poor at the initial stage of image formation, and as a result, the initial image is not foggy. Moreover, the image density becomes low and unclear. Furthermore, in intermittent image formation every 5,000 times, the rise characteristics of triboelectric charging after a pause are poor, resulting in an image at the beginning of image formation that is foggy and unclear with low image density. In addition, when forming images multiple times,
Even after the initial stage of image formation after a pause, fog gradually increases, and the image density gradually decreases, resulting in an image that becomes unclear at an early stage.

Furthermore, under high-temperature environmental conditions, more fogging occurs than under normal-temperature environmental conditions, and image density decreases and image blurring increases.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of an electrostatic image developing apparatus that can be suitably used to carry out the electrostatic image developing method of the present invention, and FIG. FIG. 2 is an explanatory diagram showing an example of an image forming apparatus that can be suitably used when forming an image. DESCRIPTION OF SYMBOLS 10... Organic photoreceptor 10A... Conductive support 10B... Photosensitive yi ti... Developing sleeve 12... Magnet 13... Regulating blade 23... Developer layer (magnetic brush) 24...Development space 30...Cabinet 31...Document 32...Document mounting table 4
0... Transfer paper 50... Organic photoreceptor 51
...Corona charger 52...Exposure optical system 53.
...Magnetic brush developer 54...Electrostatic transfer device 56...
・Blade type leaning device 1st decoy capital 2 decoys

Claims (1)

[Claims] 1) A toner containing a carrier formed by coating magnetic particles with a resin, a toner containing a nigrosine dye, and inorganic fine particles that are positively charged by friction with the carrier. An electrostatic image developer characterized by: 2) An electrostatic image developer containing a carrier formed by coating magnetic particles with a resin, a toner containing a nigrosine dye, and inorganic fine particles that become positively charged by friction with the carrier. A method for developing an electrostatic image, comprising developing a negative electrostatic latent image formed on the surface of a photoreceptor made of an organic photoconductive semiconductor using a contact magnetic brush development method.