JPS63271479A - Developer for negative charge latent image - Google Patents

Abstract

PURPOSE:To improve the flowability, electrostatic charge stability and durability by adding positive chargeable fine silica particles and oxide powder of group IVa elements to the developer. CONSTITUTION:This developer is prepd. by adding the positive chargeable fine silica particles (A) and the oxide powder of the group IVa elements (B) to the developer essentially consisting of a coated carrier and magnetic toner. The silica which is subjected to a surface treatment with an amino modified silicone compd. and has a prescribed triboelectrostatic charge quantity, average grain size and specific surface area can be used for the component A. Titanium oxide, zirconium oxide or halfnium oxide having a prescribed average particle size and specific surface area can be used for the component B. The flowability and electrostatic charge stability of the developer are thereby improved and the flawing of a photosensitive body by a magnetic brush is decreased and, therefore the images which are good even after long-term use or by a change in environmental conditions are obtd.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is directed to a photoconductor formed on the surface of an organic photoreceptor made of an organic photoconductive conductor in an electrophotographic method, an electrostatic recording method, an electrostatic printing method, etc. The present invention relates to a dry type developer for developing a negative charge latent image.

[Background of the invention]

Generally, in electrophotography, after applying a uniform layer weight to a photoreceptor having a photosensitive layer made of a photoconductive material, an electrostatic latent image is formed on the surface of the photoreceptor by imagewise 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.

Selenium photoreceptors, zinc oxide photoreceptors, cadmium sulfide photoreceptors, organic photoreceptors, etc. are known as photoreceptors, but selenium photoreceptors tend to crystallize easily in high-temperature environments and have poor heat resistance and poor sensitivity. The problem is that the image deteriorates and the image becomes unclear. Furthermore, with zinc oxide photoreceptors and cadmium sulfide photoreceptors, the photosensitive characteristics tend to deteriorate early due to image exposure, resulting in fogging, resulting in unclear images and poor durability, and they are also accused of being toxic to the human body. .

On the other hand, organic photoreceptors made of organic semiconductors do not have the above-mentioned drawbacks and have advantages such as good film forming properties, lower manufacturing costs, high sensitivity, durability, heat resistance, and no toxicity to the human body. It is a preferred photoreceptor.

Generally, a one-component developing method and a two-component developing method are known as methods for developing an electrostatic latent image formed on the surface of a photoreceptor. In the former one-component development method, a one-component developer consisting of a magnetic toner containing a magnetic substance dispersed in a binder resin is used, but since it is made of magnetic toner and does not have a carrier, it has poor triboelectric charging properties and is not easily affected by a friction band. Toner with a small single charge or toner with an opposite charge coexists, resulting in unstable developability and a stable image not being obtained. Also,
This has the disadvantage that toner adheres to non-image areas on the photoreceptor, causing smearing.

In addition, the magnetic substance contained in the magnetic toner is hydrophilic,
Triboelectric charges tend to leak in humid environments. For this reason, in the transfer process, +'fP electrical transfer to the transfer material deteriorates and the toner transfer rate decreases. As a result, image disturbance occurs on the side where the image density decreases.

On the other hand, the two-component developer used in the latter two-component development method is composed of toner and carrier, and the carrier applies triboelectric charge to the toner with appropriate polarity and appropriate charge amount! It is possible to impart much superior triboelectric charging properties compared to the component developer described above. Further, by selecting a carrier having desired characteristics, it becomes possible to control the amount of charge of the toner to a considerable extent, and it is possible to stably obtain clearer images.

However, when using a two-component developer, there are inherent problems associated with using a two-component developer, such as deterioration of the carrier, deterioration of the photoreceptor and image quality due to carrier scratching on the photoreceptor surface, carrier scattering, and toner scattering. There is a problem.

That is, in a two-component developer, when toner and carrier are stirred and mixed in a developing device to make them homogeneous, mechanical impact force causes
Some of the toner particles are crushed to form toner slag, which accumulates on the surface of the carrier particles, impeding proper frictional electrification of the carrier and toner, and causing fogging due to a decrease in the amount of electrification of the toner during long-term use. This results in toner scattering due to a decrease in electrostatic adhesion between the toner and carrier, and a decrease in image density and image disturbance due to a decrease in transferability to a transfer material, resulting in a significant decrease in durability.

In addition, when a magnetic brush is formed on a developer carrier using a two-component developer to develop a latent image on a photoreceptor, the developer easily scratches the photoreceptor and scratches the photoreceptor. Part of the image is missing (image dropout) or the developed toner image is scratched, resulting in a dark and light striped pattern (sweeping) along the development direction.
occurs. This phenomenon becomes more noticeable when the fluidity of the developer is poor.

In a two-component developer using a negatively chargeable toner, problems caused by the two-component developer are addressed, for example, by adding negatively chargeable hydrophobic silica fine particles to the toner as described in JP-A No. 45-5782. A method of adding and mixing is adopted. However, when such negatively chargeable silica fine particles are added and mixed into a positively chargeable toner, the positive frictional chargeability of l-toner is inhibited, resulting in an unclear image with a lot of fog.

Taking these circumstances into consideration, a method is known in which the surface of silica fine particles, which are originally negatively chargeable, is modified to be positively chargeable by treating the surface and added to toner.
3-22447 and JP-A-58-185405 disclose inorganic fine particles treated with an aminosilane coupling agent, and JP-A-59-187359 discloses silicic acid fine particles treated with silicone oil having an amine in the side chain. It is known. By adding and mixing such positively chargeable silica fine particles into toner, clear images with relatively little fogging can be obtained, but a fully satisfactory solution has not yet been reached. Furthermore, all of the problems caused by the interaction with carrier particles described above have not yet been solved.

That is, a charge control agent is usually added to a toner in order to impart desired polarity and triboelectric charge amount. The method of addition is to mix it into the binder resin, melt it, knead it, and disperse it into the toner. However, the charge control agents used as charge control agents are generally dyes and pigments, which are susceptible to thermal decomposition during melting and kneading, deterioration due to temperature and humidity, and are difficult to uniformly disperse in the binder resin, so they do not last long in toner. It is difficult to provide stable charging properties. If a two-component developer is prepared using a toner containing such a charge control agent, the toner may quickly become abrasive during long-term use. i? The conductivity decreases, causing fogging and a decrease in image density. Furthermore, when the toner and carrier are stirred in the developer container, charge control agents that are friable or poorly dispersed in the toner particles are liberated, and these liberated substances adhere to the carrier particles, the surface of the photoreceptor, or the developer carrier. It accumulates and contaminates, impairs the triboelectric charging properties of the toner, and also causes deterioration of the properties of photoreceptors, reducing their durability.

Addition of the positively chargeable silica fine particles may be considered as a means to solve the problems caused by such charge control agents, but the improvement is only slight. On the contrary, the use of positively chargeable silica fine particles reduces the cleaning effect of the cleaning blade on residual toner on the photoreceptor, worsens the initial chargeability of toner and carrier under high temperature and humidity conditions, and reduces the rise of charge. Even worse, fogging is likely to occur in the initial image. Further, the positively chargeable silica fine particles are released from the toner surface and adhere to the carrier particle surface due to the mechanical force received in the developing device. The triboelectric chargeability of the carrier is reduced, and the durability of the developer is significantly reduced.

[Purpose of the invention]

The present invention has been made in order to solve the above-mentioned conventional problems as much as possible.

That is, the purpose of the present invention is to provide (1) a developer for developing a negative charge latent image that has high triboelectric chargeability of the toner, is stable, and provides a clear image without fog; (2) has good transferability. (3) A negative charge latent image developer that has good developer fluidity and can achieve uniform development and produce images without sweeping marks; (4) ) Negative charge latent image developer with excellent environmental resistance and stable triboelectricity with good initial rise even under high temperature and low temperature and low humidity environmental conditions; (5) carrier made from crushed toner particles; (6) Negative charge latent image developer with good durability that avoids contamination of the photoreceptor surface, negative charge latent image with good cleaning effect when cleaning (6) residual on the photoreceptor surface with a cleaning blade The objective is to provide a developer.

[Means to achieve the purpose]

The object of the present invention can be achieved by a negatively charged latent image developer containing a coated carrier, a nonmagnetic toner, positively charged silica particles, and Na group element oxide particles.

[Operations and Effects of the Present Invention] According to the developer of the present invention, negative charge latent images can be developed well without impairing the advantages of organic photoreceptors, and image quality such as high fog-free images and density change can be achieved. It is possible to obtain good images and has good operational durability.

In the present invention, surface-treated positively chargeable silica fine particles are added to the toner in order to improve the fluidity of the developer, impart a stable and high positive triboelectric charge to the toner, and improve moisture resistance. . This makes the photoreceptor less likely to be damaged, and it is possible to largely eliminate image omissions and image sweeps.

In the present invention, in addition to the positively chargeable silica particles, oxide particles of an rVa group element are added to the toner. By blending the developer in this manner, the developer exhibits even more excellent P1 tribocharging properties, and even during long-term use, fluctuations in electrostatic charges are reduced, and durability can be improved. That is, by adding fine particles of oxide of group I/A elements, fine particles of oxide of group IVa elements are interposed between the toner and carrier particles, and crushed slag of toner particles is generated and liberated to form carrier and carrier particles. The surface of the photoreceptor is prevented from being contaminated, the cleaning blade is less likely to be damaged, and cleaning defects caused by positively charged silica particles can be prevented. Furthermore, since the triboelectric charging efficiency of the toner and carrier is significantly improved, even under high temperature and high humidity environmental conditions, the initial charging rise is good and a good image can be obtained without fogging.

Further, the present invention is directed to coated carriers, which serve to prevent the adhesion of loose l-toner scum and particulates added to the toner.

In addition, the developer of the present invention has good fluidity and charging stability, and has good developer fluidity and charging stability by having a coated carrier, a non-magnetic toner, positively charged silica particles, and IVa group element oxide particles as constituent elements. Because the abrasion of the photoconductor caused by the magnetic brush of the agent becomes smaller and smaller, the gradation reproducibility and resolution become noticeably better, and even after long-term use or changes in environmental conditions, images remain as good as the initial excellent images. It is a developer with excellent environmental resistance and durability.

[Specific structure of the invention]

The positively chargeable silica fine particles in the present invention include the following 1
It belongs to 111G. That is, the temperature is 20℃,
0.2 g of silica microparticles left overnight under environmental conditions of 60% relative humidity and uncoated ferrite particles (e.g.
Japanese iron powder pillar! MF-150) 19. With Flg.”
- Under the above conditions, the amount of triboelectric charge on the silica particles was determined by shaking for 5 minutes in a glass sample container with a volume of approximately 20 cc, and then using a standard blow-off method using a stainless steel cell with a 635 mesh screen. The result is a positive triboelectric charge.

The positively chargeable silica fine particles have a triboelectric charge of +10 μC/g or more, particularly +30 μC in the above measurement.
/g or more is preferable. If the amount of triboelectric charge is too small, the positive triboelectricity of the non-magnetic toner deteriorates and the amount of triboelectricity decreases, resulting in fogging or
The durability of the developer may decrease.

The positively chargeable silica fine particles are surface-treated silica fine particles. Examples of substances that can be used for the surface treatment include amino-modified silane coupling agents, amino-modified silicone oils, amino-modified silicone varnishes,
Amino-modified silicone compounds such as amino-modified silicone rubber, amino-modified silicone resin, or cured products thereof can be preferably used. Amino-modified silicone varnishes, amino-modified silicone rubbers, amine-modified silicone resins, or cured products thereof are preferred because they provide particularly excellent positive chargeability, moisture resistance, and durability. According to the treated silica fine particles, the presence of the amine group makes the silica 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 silica fine particles. are strongly bonded together, resulting in silica fine particles that are excellent in moisture resistance and durability, and have stable positive triboelectric charging properties that are not affected by environmental conditions.

As the amino-modified silicone varnish preferably used to obtain positively chargeable silica fine particles, for example, amino-modified methyl silicone varnish, amino-modified phenylmethyl silicone varnish, amino-modified phenyl silicone varnish, etc. can be used, and in particular, amino-modified The amino-modified silicone varnish, which is preferably a methyl silicone varnish, has a T11 unit, a D unit, an M'' unit shown in the following structural formula, and a group in which some of the organic groups present in each of these units have an amino group. It is a three-dimensional polymer consisting of m-position converted to i and containing 10 to 90 mol%, preferably 30 to 80 mol% of T1 units.When the proportion of the T" units is too small, adhesiveness As a result, the stability of triboelectric charging properties is reduced, and the carrier may be contaminated, resulting in a reduction in the durability of the developer. On the other hand, the T
``If the ratio of units is too large, the cleaning blade becomes more likely to be damaged due to excessive hardness, and as a result, cleaning defects are more likely to occur.

(T” unit) ([)l 1 unit] [M
-1 unit] R” R”-5i-0- h... In each unit, Rth Rl 2, R13t (+ 4,
RI S and R eyes are an alkyl group such as a methyl group or an ethyl group, an aromatic group such as a phenyl group, a polyether group, a hydroxyl group, and an amino group, respectively.7. ! ; Represents an organic group such as;

For example, it is a substance having the chemical formula (1) shown below.

Structural formula (1) %Formula% Here, R17 and R1@ represent an organic group such as a methyl group or a phenyl group.

The amino-modified silicone rubber preferably used to obtain positively chargeable silica fine particles includes, for example, a D" unit represented by the horizontal formula below, and a part of the organic group present in the unit is an amino group. j1 substituted with a group having
It is a long-chain polymer consisting of

CD 21 units: ] [1) 22 units] 0-5i-0-0-5i-0- R22CH=CH2 In each unit, R", r (22, R2 is an alkyl group such as a methyl group or an ethyl group. , aromatic groups such as phenyl groups,
Represents a polyether group, hydroxyl group, amino group, etc.

Further, in order to make the silicone rubber into a crosslinked structure, it is preferable to copolymerize with D2222 monomer indigo represented by the above structural formula.

The amino-modified silica resin preferably used to obtain positively chargeable silica fine particles has the above-mentioned T day unit and the above-mentioned D''
It is a polymer consisting of units in which a part of the organic groups present in the Ml+ unit and each of these units is substituted with a group having an amine group, and unlike silicone oil, it is a polymer that contains a large amount of T-day units. be.

In the amino-modified silicone varnish, especially T1
The unit imparts good thermosetting properties, and furthermore, the T
The amino-modified silicone rubber has a 13A bridge structure due to the D'' unit, and the amino-modified silicone resin has many branches due to the T'' unit, resulting in a cross-linked structure. +1 structure and a cyclic structure is formed within the molecule. As a result, the silica fine particles having the above-mentioned silicone compound on the surface form a tough coating on the surface and have excellent impact resistance, moisture resistance, and mold release properties.

In addition, amino-modified silicone varnish, amino-modified silicone rubber, and amino-modified silicone (31 fat) contain a considerable amount of silanol groups that have 011 groups without forming siloxane bonds, so these silanol groups are Reactions such as dehydration condensation with the functional ly present on the surface of the siloxane bond result in the formation of siloxane bonds during curing, resulting in the coating having even stronger properties.

In addition, in the case of amino-modified silicone varnish, examples of curing accelerators that can be used to accelerate the curing reaction include fatty acid salts such as zinc, lead, cobalt, and tin;
Amines such as triethanolamine and butyl 7mi7;
etc. can be used. Among these, amines can be particularly preferably used. In addition, in the case of amide/modified silicone rubber, known vulcanizing agents can be used, specifically, for example, benzoyl peroxide, bis-2
, 4-nochlorobenzoyl peroxide, di-t-butyl peroxide, dicumyl peroxide and the like can be preferably used.

Further, as the group having 7 amino groups in the amino-modified silicone varnish, amino-modified silicone rubber, and amino-modified silicone resin, those represented by the following formula #lq are preferable, for example.

-CH□CH2-NH2 -CH, (CH2)2-NH2 -CH2(CH2)2-NH-(CH2), -NH2 Positively chargeable silica fine particles-
As the modified silane camping agent, for example, a compound represented by the following chemical formula is preferable.
C1lzC1(=Si(OC113)3C1l.

1'1zNC11,CI(=C112S+(OC211
q) 2CI+3 112N Glf2C112CII2S+(OCHL)
2CI+3 112NC112CIT, N11C11, (jlzcl
l, 5i(OCHL,)2H: N CH2CN2 N
HCH2CH2CH2S1((”) C[(s)iC
llzCHzSi(OCHL:h H, C2OCOCH2CI42NtlCt12CII2
CII2-Si(OC1(s)i (HsCz)2N CH2CI! 2CII 2Si(
OCH3)
% be able to do it.

General formula (A) Here, R41 represents an alkylene group, an aryl group, an ami/alkylene group, etc., and R12 and R" each represent a hydrogen atom, a humanyl group, an alkyl group, a 7-aryl group, etc. , x, and y each represent an integer of 1 or more.

The amino-modified silicone oil preferably has an amino equivalent value within the range of 300 to 10,000. When the value of amino 7 equivalent is too small, the effect of imparting positive chargeability by the silica particles is small, resulting in a foggy and unclear image. On the other hand, when the value of amino equivalent is too large, the silica particles become a carrier. It tends to transfer and adhere to particles, and the durability of the image forming agent may be reduced.

Examples of commercially available amino-modified silicone oils that can be preferably used include the following! Examples include those listed in Table 161.

Primary particles of silica fine particles whose surface is treated with the above compound (particles separated into individual 41st particles)
It is preferable that the average particle diameter is within the range of 3111μ to 2μIll.

Such fine silica particles have Si 0 -Si bonds. They are fine particles and may be produced by either a dry method or a wet method, but those produced by a dry method are preferable because they provide good fluidity and moisture resistance of the developer. Preferably, the particles are silica particles produced by vapor phase oxidation of a compound. Furthermore, as the silica fine particles, in addition to silicon dioxide (silica), fine particles made of silicates such as aluminum silicate, sodium silicate, calcium silicate, potassium silicate, zinc silicate, and magnesium silicate may be used. % or more is preferable.

As a method for treating the surface of silica fine particles with the above compounds, known techniques can be used. Specifically, for example, using a fluidization bed device, a solution of the above compound components dissolved in a solvent can be used. A method may be used in which the coating is spray-coated onto fine silica particles and then heated and dried to remove the solvent and cure the coating.

The particle diameter of the positively chargeable silica fine particles surface-treated (coated) with the above-mentioned compound is such that the average diameter of the primary particles is 3 μm to 2 μm, particularly 5 μm to 500 μm.
-μ is preferably within the range. Also, +1
The specific surface area measured by the 1ET method is preferably 2020-5O0/g. If the average particle diameter is too small or the specific surface area is too large, fine silica particles may slip through during cleaning using a blade-type cleaning device, or poor refreening may occur. - When the force and average particle size are too large or the specific surface area is too small, the fluidity of R-cutting decreases and the developability deteriorates, resulting in a decrease in image density and the occurrence of streaks in the image. There are cases.

The silica powder consisting of positively chargeable silica particles is as follows:
By being added to the non-magnetic toner powder, it is attached and retained on the surface of the non-magnetic toner particles.

The content of the positively chargeable silica image particles is preferably 0.1 to 5% by weight, particularly preferably 0.1 to 2% by weight, of the nonmagnetic toner. If the content of positively chargeable silica fine particles is too small, the fluidity of the developed Rokuyo may decrease, resulting in poor triboelectric charging properties of the non-magnetic toner, and the non-magnetic toner may not have the correct amount of charge. It becomes difficult to apply charges, and ζζ distortion or image distortion may occur. Also, when the content ratio is too high, some of the positively charged silica particles become non-magnetic toner particles! As a result, the positively charged silica particles may be attached to the carrier particles.
The non-magnetic toner may be transferred or deposited on the developer carrier, regulation blade, etc., and eventually the triboelectric charging properties of the non-magnetic toner become poor, making it difficult to apply an appropriate amount of positive charge, resulting in fogging and poor image density. Deterioration may occur.

Examples of the IVa group element oxide powder used in the present invention include titanium oxide, zirconium oxide, and hafnium oxide. As titanium oxide, titanium oxide (II
): Ti01 titanium oxide (1■): T! 2oz, titanium oxide (rV): There is TiO□.

Titanium (II) oxide is titanium (IV) oxide with carbon or 1
j obtained by reduction with a metal (e.g. zinc),
It is a black columnar powder with a pongee crystal system. Titanium oxide (I[I)
is a hexagonal black-purple crystal powder obtained by oxidizing and reducing titanium (IV) with a mixture of hydrogen and titanium (IV) chloride. Titanium (IV) oxide has three types of metamorphosis with different supplements: brookite type, rutile type, and anatase type. To produce it in the laboratory, the hydroxide is precipitated and separated from an aqueous solution of titanium (IV) salt and then ignited. A rutile type can be obtained by baking at a high temperature, and an anatase type can be obtained by dissolving titanium oxide (1%') powder little by little in a molten salt of potassium hydrogen sulfate. When a tetravalent titanium halide is passed through a red-hot tube together with water vapor and carbon dioxide, an brookite type is obtained. The brookite type is a black-brown orthorhombic crystal powder, the anatase type is a black-brown tetragonal crystal powder, and the rutile type has a variety of colors from colorless to black.

Zirconium oxide (Z"0□) is obtained by heating zirconium hydroxide, and there are two types: varabrilite type and turphea type. The former is a yellowish white to brown monoclinic crystal, and the latter is a white crystal powder. It is.

Hafnium oxide II f O2 is a white monoclinic crystal powder obtained by igniting hafnium hydroxide.

The particle size of the IVa group element element oxide fine particles according to the present invention is such that the average particle size of the primary particles is 0.005 to 3.0 μm, and the BE
It is preferable that the specific surface area measured by the T method is 1.0 to 150 m2/g. When the average particle size is too small or the specific surface area is too large, cleaning defects are likely to occur during blade-type cleaning, while when the average particle size is too large or the specific surface area is too small, the developer flow As a result, the image density may be lowered or streaks may occur in the image.

The IVa group element oxide fine particles are mixed as a powder with the nonmagnetic toner particles, thereby being attached and retained on the surfaces of the nonmagnetic toner particles.

The content of the fine particles of oxide of group 11/a elements is preferably 0.01 to 5% by weight, particularly preferably 0.05 to 2% by weight of the nonmagnetic toner.

When the content of the IVa group element oxide fine particles is too small, the fluidity of the developer may decrease, resulting in poor triboelectric charging properties of the non-magnetic toner, making it difficult for the non-magnetic toner to have an appropriate amount of charge. It becomes difficult to apply a positive charge, and fogging or sweeping of images may occur. In addition, when the content ratio is excessive, some of the oxide particles of the IVa group element may exist in a state separated from the non-magnetic toner particles, and as a result, the free oxide particles of the u group element become carriers. It adheres and transfers to particles, or it adheres and accumulates on developer carriers, regulation blades, etc., and eventually the triboelectric charging properties of the non-magnetic toner become poor at an early stage, and an appropriate amount of positive charge is imparted to the non-magnetic toner. This may result in fogging or a decrease in image density.

The non-magnetic toner constituting the negative charge latent image developer of the present invention is basically particles composed of a binder (oil) containing a coloring agent and other additives, and the average particle size of the non-magnetic toner is The diameter is preferably 5 to 20 microns.

Other additives that can be used include, for example, fixability improvers, charge control agents, and the like.

Binder that makes up non-magnetic toner? ! ! +111 is not particularly limited and various resins can be used.

Specifically, for example, polystyrene resin, styrene-acrylic copolymer, poly-styrene-butadiene is sealed, polyester resin, epoxy resin, polyamide (]I
resin, polyurethane resin, etc. can be used. In particular, polymers can be preferably used for styrene-acrylic systems, and among them, copolymers obtained by polymerizing styrene-11t ffi and acrylic acid or its ester and/or metal acrylic acid or its ester are used. It can be preferably used.

In the styrene-acrylic copolymer, the styrene component is preferably contained in an amount of 95 to 60% by weight of the copolymer. If the proportion of the styrene component is too large, the copolymer may become brittle and the durability of the non-magnetic toner may be reduced. On the other hand, if the proportion of the styrene component is too small, the copolymer tends to transfer and adhere to the wall of the developing device, and as a result, the triboelectric charging properties of the nonmagnetic toner may be inhibited.

A specific example of one styrene-based Qt that can be used to obtain the styrene-acrylic copolymer is as follows:
For example, styrene, 0-methylstyrene, -methylstyrene, p-methylstyrene, α-methylstyrene, ■+-
Ethylstyrene, 2,4-dimethylstyrene, p-1 biptylstyrene, 1)-L-butylstyrene, p-1 bihequinrustyrene, p-11-octylstyrene, 1l
-n-7 nyl styrene, 11-I+-decyl styrene, ρ-1 bidodecyl styrene, p-methoxystyrene,
p-phenylstyrene, 1)-chlorostyrene, 3,4
- Lauryl styrene, etc. can be mentioned. These monomers may be used alone or in combination.

Further, examples of the acrylic component that can be used to obtain the styrene-acrylic copolymer include acrylic acid, methyl acrylate, ethyl acrylate, acrylic Q n-butyl, isobutyl acrylate, propyl acrylate, 1-bioctyl acrylate, dodecyl acrylate, lauryl acrylate, llI22-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl a-chloroacrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, methacrylic acid n
-Butyl, isobutyl methacrylate, methacrylic W11
a-notylene aliphatic monocarboxylic acid esters such as 1-octyl, dodecyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl tuacrylate, diethylami/ethyl methacrylate;
Acrylic acid or methacrylic acid derivatives: Others may be mentioned. These Qj ff1 bodies may use a single tl or a combination of a plurality of tl.

As a method for producing the styrene-acrylic copolymer, for example, a solution polymerization method, a suspension polymerization method, an emulsion polymerization method, etc. can be used.

Examples of colorants include carbon black, 7-thalocyanine blue, benzunone yellow, nigrosine dye, aniline blue, carfoil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, malachite, green off-salate, Dyes and pigments such as 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 nonmagnetic toner.

As the fixability improver, for example, polyolefins, fatty acid esters, fatty acid ester waxes, solid paraffin waxes, 7-mide waxes, silicone varnishes, aliphatic 70 carbons, and the like can be used.

Examples of the charge control agent include nigrosine dyes, metal complex dyes, ammonium-based intermediates, aminotriphenyl-thane dyes, and polymers in which the amine 7 group moves to the right, such as styrene-dimethylaminoethyl methacrylate co-mer. etc. can be used.

As the coated carrier constituting the developer used in the present invention, carriers having various configurations can be used. Specifically, a coated carrier in which the surface of magnetic particles is treated with a silicone compound or a fluorine resin is preferred.

Examples of compounds used in the coating carrier include silicone-based compounds such as silane coupling powder, silicone oil, silicone varnish, silicone rubber, silicone fl (Iff↑) or cured products thereof; for example, vinylidene fluoride-tetrafluoride. ethylene copolymer, tetrafluoroethylene, methyl methacrylate-methacrylic l'7
-1.1-hydroxyverfluoroethyl conjugate,
It is preferable to use a fluorine-based resin such as a snalene-methacrylic acid-1,1,3-trihydroxyperfluoro-11-propyl copolymer. The above substances may be used alone, or a plurality of them may be used in an appropriate combination.

Among these substances, silicone-based compounds are particularly preferably used because they provide excellent developability and chargeability, and among them, silicone varnish, silicone rubber, and silicone 11! (Jiff or a cured product thereof can be particularly preferably used. In a coated carrier obtained using such a silicone compound,
The surface energy is considerably reduced, and as a result, the transfer of toner material or positively charged silica particles to the carrier particles becomes possible.

Also, silicone varnish, silicone rubber, silicone? As 1 rM, an alkyl group as the configuration + 11th position,
Those having an organic group such as an aromatic group 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 dimethylpolysiloxane, methylphenylpolysiloxane, 7enylbolysiloxane, and
For example, the degeneration of In particular, polysiloxane having a methyl group or a 7-enyl group has excellent negative charging properties, and when a coated carrier obtained by using this polysiloxane and a non-magnetic toner are tribo-electrified, the non-magnetic toner has good properties. A positive triboelectric charge can be applied. and,
By appropriately selecting the content ratio of methyl group and phenyl group in the above organic group, the hardness of the coating of CA 177,
Toughness, J? It is possible to adjust the characteristics such as tribostatic properties, and therefore it is possible to adjust the characteristics such as tribostatic properties.

This has the advantage that the conditions required for the non-magnetic toner used in combination with the rear toner are considerably relaxed, and the selection range of non-magnetic toner is wide.

Commercially available silicone varnishes include, for example, rS
R2101J, rsl+997J, rSH994J, r
sR2202, I, rSE9140 Jrs11643
4, "311204," JcR6100J, l'Jc
R61011 (hereinafter "-, manufactured by Tomu Silicone Co., Ltd.),
jKR271J, [KR272,l, "niR2)4",
[KR216J, “KR280J, jK8282
J, "KR26jl," to R260J, [to 1125
5J, r to R2661, I-KIt251J, [KR1
551, "KR1521, [KR214J," to R22
0J, rX-40-171J, [niR20jl, "S^
-41, I K R5202J, [to R30931, I
'EC1001J (hereinafter referred to as '-manufactured by Shin-Etsu Chemical Co., Ltd.) and the like can be mentioned.

As a commercially available silicone rubber, for example, [5l
1410J, r S I+ 432 J, jslI43
3J, r S 11740, l, l' S I+ 3
5 U J, [5H75UJ, [511841UJ, r
s111125, 1sI11603tlJ, jsH6
65UJ, jsE955UJ, [S 115020 J
, [5RX-440UJ (manufactured by Tomu Silicone Co., Ltd.), and the like.

Further, when forming a VL-covered carrier using the silicone compound as described above, a curing agent may be used as necessary. Examples of such curing agents include peroxides such as benzoyl peroxide, 2,4-nochlorobenzoyl peroxide, tsucumyl peroxide, tert-butyl peroxide, and tert-butyl perbenzoate; octylic acid, naphthenic acid. metal soaps such as lead, iron, cobalt, manganese, and zinc; organic amines such as ethanolamine; and the like.

The magnetic particles constituting the carrier include substances that are strongly magnetized in the direction of the magnetic field, such as iron, ferrite,
Particles made of ferromagnetic metals or alloys such as iron, nickel, and cobalt, including magnetite and tite, or compounds containing these elements, can be used, and ferrite particles, which do not cause carrier scattering, are particularly preferred.

The method for producing the coated carrier is not particularly limited, but for example, a coating solution prepared by dissolving the coating components and a curing agent used as necessary in a solvent is applied to the surface of the magnetic particles, and then heated. Dry to remove the solvent by volatilization,
It can be manufactured by thermally curing the coating IN'1g as required.

The coating method is not particularly limited, but includes, for example, a dipping method in which powder of magnetic particles is immersed in a coating solution, a spray method in which the coating solution is sprayed onto the magnetic particles, and a method in which the magnetic particles are suspended using fluidized air. A fluidized bed method or the like can be used in which a coating liquid is sprayed onto the magnetic particles in the state.

As the solvent for the above-mentioned coating liquid, for example, toluene, xylene, acetone, methyl ethyl ketone, tetrahydroctane, dioxane, higher alcohol, or a mixed solvent thereof can be used.

The average particle diameter of the spear 7 is preferably 5 to 500 μm, and preferably 20 to 200 μm. 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. When is excessive, image unevenness may occur. Note that the average particle diameter (weight ft) of the carrier is a value measured using "Tai Micro Track" (manufactured by Nikkiso Co., Ltd.).

The organic photoreceptor according to the present invention is constructed by laminating a photosensitive layer in which a photoconductive semiconductor made of an organic compound is dispersed in a resin binder on a conductive support made of, for example, aluminum or stainless steel.

The photosensitive layer may be a carrier generating substance that absorbs visible light and generates charge carriers, such as an anthurone compound, a perylene derivative, a bisazo compound, a 7-talocy7ine compound, or a styrene-methyl methacrylate copolymer. , a carrier generation layer dispersed in a binder 01 resin such as polycarbonate resin or silicone resin;
A carrier transport layer containing a carrier transport substance that transports carriers generated in the carrier generation layer, such as oxanoazole derivatives, triarylamine derivatives, polyarylalkane derivatives, hydrazone derivatives, stilbene derivatives, and styryl 177 arylamine derivatives. It is preferable to use a functionally separated photosensitive layer formed by combining the following.

〔Example〕

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

(gR preparation of silica fine particles) (1) Silica fine particle AI (Example) configuration')t (
It,! -L Te, below D'lit position, below A
It has the Dl+1t position and the following T1tlt position, the molar ratio of these is 4:1:5, it has an 011 group at the end, and the viscosity at 25°C in a xylene solution with a concentration of 30% by weight is 50 to 200. cl] ++ amino-modified silicone resin was dissolved in xylene, and then processed into J! l! A liquid was prepared.

(D' single α) (T' unit) [Go to ○' unit] Next, silica fine particles [Aerosil 200J (
Put 11 pieces (manufactured by 7 Kosil Co., Ltd.) into a mixer, and add 2 pieces of amino-modified silicone varnish to 2 pieces of silica fine particles.
After spraying at a ratio that gives 0% double spraying, these were placed in a flask, and while stirring, the solvent xylene was removed at a temperature of 200 ° C. for 5 hours, and the 7-mino-modified silicone fuss was caused to undergo a curing reaction. As a result, surface-treated positively chargeable silica fine particles were obtained. This is referred to as silica fine particles AIJ.

This silica fine particle-A1 has a primary particle average particle size of 12
mμ, specific surface area measured by IIET method is 110+a'/g.

In addition, uncoated ferrite grains 7-[F-150,1(
11 (manufactured by Tetsuko Co., Ltd.), the amount of frictional electrification is +72 μC/g.

(2) Silica fine particles A2 (Example) As the structural unit, the above D'tl+, D2 unit below, 〇211
j-position, and their molar ratio is 5:2:3,
Viscosity at 25°C is 6 x 10'cps, average molecular weight is 7
XtO' amino-modified silicone rubber and 2% by weight of benzoyl peroxide based on the amino-modified silicone rubber are dissolved in xylene, and the treatment solution is 'I! 4 were made.

(1) 2 units] C11゜-0-5i-0- CII=CI+2 [^[1213th place] C11゜-0-S i -0- CI+, <CI+2>2Nll (C112), Nll□
Next, silica fine particles "Aeronol 300.1 (manufactured by Nippon Aeronol Co., Ltd.) were placed in a mixer, and a treatment liquid was sprayed onto the silica fine particles in such a proportion that the amino-modified silicone rubber contained in 1. Other than that, the surface treated positively chargeable silica fine particles were obtained in the same manner as in the production of silica particles A1.
1. The silica fine particles A2 have an average primary particle diameter of 7 all and a specific surface area of 14 by the DET method.
5 bites is 27g. In addition, uncoated 7-elite particles [F-
Frictional charge amount with 150J (Japan Iron Powder Co., Ltd. 91) is +162
μC/g.

(3) Silica fine particles A3 (Example) have the above D1 unit, the above D2 unit, the following 〇' unit, and the above T1 unit as constituent units, and the molar ratio of these is 4.5: 1.5
: 2 : 0.5 for amino-modified silicone rubber of 2 and this amino-modified silicone Ij1 fat
% by weight of benzoyl peroxide is dissolved in xylene,
A treatment solution was prepared.

[in units of 〇〇〇〇]

C11°N Next, silica fine particles [Aairsil 200.1 (manufactured by Nihon Aerosil Co., Ltd.) were placed in a mixer, and the above amino-modified silicone resin was added in such a proportion that the proportion of the above amino-modified silicone resin was 30% by weight relative to the second silica fine particles. Place J! The particles sprayed with Liquid I were treated in the same manner as in the production of silica fine particles A1 to obtain surface-treated positively chargeable silica fine particles. This is called "Silica fine particles A3J"
Toru. The second silica fine particles A3 have an average primary particle diameter of 12 mμ and a specific surface area of 82 m2/2 by IIET method.
It is g. In addition, uncoated 7 elite particles 1'F-150
The amount of frictional electrification with J (manufactured by Nippon Tetsuko Co., Ltd.) is +81 μC/g.

(4) Silica fine particles A4 (Example) Silica fine particles
7 Aeronol 200J (manufactured by Nippon Aeronol Co., Ltd.) 100
A solution of 7-mino-modified silicone oil dissolved in isopropyl alcohol (viscosity (25°C)
= 1200cps, 7min hit ffi = 3500
) was stirred at high speed while spraying at a rate such that the amount of amino-modified silicone oil treated was 2.0% by weight, and then dried at a temperature of 150°C, thereby producing positively chargeable silica fine particles whose surface was treated. I got it. This is referred to as "silica fine particles A4J." The second silica fine particles A4 has an average primary particle diameter of 12aiμ and a specific surface area of 12μ by the anal T method.
0 m"/g. Also, uncoated ferrite particles rF-
The amount of frictional charge with 1504 (manufactured by Nippon Tetsuko Co., Ltd.) is +110μ
C/s.

(5) Silica fine particles A5 (Example) Silica fine particles
Aeronol 300J (manufactured by Nippon Aeronol Co., Ltd.) at 70℃
The silica particles were placed in a Henschel mixer heated to 171, and a solution of γ-7 minoprobyl triethoxysilane, an amino-modified silane coupling agent, dissolved in alcohol was added to the silica particles. Coupling agent place F! ! The mixture was stirred at high speed while being sprayed at a ratio such that TFT was 5.0% by weight, and then dried at a temperature of 120°C, thereby obtaining surface-treated positively chargeable silica fine particles. This is [Silica fine particles A 5
．． Let it be l.

The silica fine particles A5 have an average primary particle diameter of 8 μm.
, the specific surface area by the 11ET method is 151+*2/g.

Further, the amount of frictional electrification with uncoated ferrite particles rF-150J (manufactured by Nippon Tetsuko Co., Ltd.) is +94 μC/g.

(6) Silica fine particles A6 (comparative example) A negatively charged silica image scoop [R-972J (E1 bottle 7 manufactured by Elonor) was used as silica fine particles A6. The silica fine particles A6 have a triboelectric charge amount of 1200 μC/g with non-7I ferrite particles [F-150J (manufactured by Nippon Tetsuko Co., Ltd.)].

(Fine particles of oxide of group IVa elements) (1) Average particle size 20 μm, BET value 100 m”/
gf) a Titanium 0x fine particles
ide P25 (manufactured by Japan 7-Rosil Co., Ltd.) is set to 81.

(2) Average particle size 21 mμ, BET value 3oII12/
82 is titanium oxide fine particles (T-805: manufactured by Nippon Aerosil Co., Ltd.).

(3) Norconium oxide (Zr02: manufactured by Kanto Kagaku Co., Ltd.) is pulverized in a Couette mill and then sieved to obtain fine particles B3 with an average particle size of 1.1 μm and an ET value of 4.1 μm/g. Obtained.

(4) Hof oxide 2') A (Hf02: I!f
(Manufactured by Taku Kagaku Co., Ltd.) After grinding with a Wojet mill and sieving, the average particle size is 0.8μ, and the IIET value is 5.
Fine particles 134 of m2/g were obtained.

(Manufacture of CA 177) (1) 8 parts by weight of Carrier C1 silicone varnish [SR-2101J (manufactured by Le Silicone Co., Ltd.)] was mixed with spherical copper-zinc 7-grade light particles ( Nippon Tetsukosha 91)! Spray coat on 00 heavy f1n and further heat at 200℃ for 5
After sintering by heat treatment for a period of time, the agglomerate was then sieved to produce a carrier with a coating layer of sintered silicone varnish. This is called “Career CIJ”
This carrier C1 has an average particle size of 102 μm.

(2) Carrier C2 In manufacturing carrier C1, silicone rubber [511
-2047J (manufactured by Le Silicone Co., Ltd.) Sffi amount part, benzoyl peroxide 0.05 overlapping part, and spherical copper -
The same treatment was performed except that 100 parts by weight of zinc ferrite particles (manufactured by Nippon Tetsuko Co., Ltd.) were used to produce C-97 having a coating layer made of a sintered product of silicone rubber. This is referred to as [Carrier C2J. This carrier C2 has an average particle size of 81 μ-.

(3) Carrier C3 Spherical copper-zinc ferrite particles (manufactured by Nippon Iron Powder Co., Ltd.) were added to a coating solution prepared by dissolving 2 parts by weight of carrier C3 silicone resin rSR-2400J (manufactured by Le Silicone Co., Ltd.) in 50 parts by weight of xylene. ) After immersing the took amount, it was heated to volatilize and remove the solvent xylene, and then heated at 200°C for 5 hours.
After sintering by heat treatment for 100 m, the agglomerate was then sieved to produce a carrier with a coated scrap of sintered silicone 1Jfffff.

This is called [Carrier C3]. This car 177 C
No. 3 has an average particle size of 60 μm.

(4) CA97C4 15 of the above polymer. A mixed solvent of a7tone and notyl ethyl ketone (mixed volume ratio = 1:1) 500
A coating liquid is prepared by dissolving the coating liquid in M &
After heat treatment at 00° C. for 5 hours, the 4I collection was sieved to produce a carrier 7 having a coating layer. Let's call this "Carrier C, 4J."

This carrier C4 has an average particle size of 80 μm.

(5) Carrier C5 styrene-methyl ethacrylate copolymer (monomer composition ratio = 30:70) 15 g of methyl ethyl ketone 3
00ial to prepare a coating liquid, and then apply the above coating liquid to spherical copper-zinc 7-layer light particles 1 using a spira coater 1 (VQ Ta Seiko Co., Ltd.), and then heat the coating liquid. This was dried to produce a carrier having a coating layer.This is referred to as "Carrier C5J".
has an average particle size of 110μ.

(For non-magnetic toner!!) (1) Toner T1 100 parts by weight of poly-styrene-〇-butyl acrylate copolymer (monomer composition ratio = s2: 18), carbon black [Mogul LJ (Cabot Corporation!)] Little
o parts by weight and 2 parts by weight of "Nigrosine SO" (Orient Chemical Industry Co., Ltd.) were mixed using a V-type preng, then melted and kneaded using two rolls, then cooled, coarsely ground using a hammer mill, and further Finely pulverized with a Noet mill, then classified with an air classifier, with an average particle size of 11.0
A μ-sized non-magnetic toner was obtained. This [Toner TIJ
shall be.

(2) Toner 72 In the production of toner T1, styrene-n-butyl acrylate-7-methyl methacrylate copolymer (monomer composition ratio = 70:20:10) was used instead of styrene-n-butyl acrylate copolymer. ) A nonmagnetic toner having an average particle size of 10.5 μl was obtained in the same manner except that 100 parts by weight was used. This is referred to as "Toner T2J.

(3) Toner T3 In the production of toner T1, styrene-n-butyl methacrylate copolymer (monomer composition ratio = 65:3) was used instead of styrene-+1-butyl acrylate copolymer.
5) Using 100 parts by weight, a non-magnetic toner having an average particle size of 11.3 μm was obtained in the same manner. This is referred to as [toner T3J].

(Preparation of developer) A developer was prepared in the following manner using carrier, toner, silica fine particles, and 71/a group element oxide fine particles in combinations and amounts shown in Table 2 below.

That is, first, fine silica particles are added to the toner from the outside, and these are mixed in a Henschel mixer to adhere the fine silica particles to the surface of the toner particles, and then fine particles of oxide of group IVa elements are adhered in the same manner. A developer was prepared by mixing with a carrier.

(Organic latent image carrier) (1) Organic latent image carrier P1 A negatively chargeable 2MM photosensitive layer formed using 7th Anthrone M as a carrier generating substance and a carbazole derivative as a carrier transporting substance. , an organic latent image carrier was constructed by laminating it on a drum-shaped aluminum conductive support. This is referred to as "organic latent image carrier PIJ".

(2) Organic latent image carrier P2 An organic latent image carrier was constructed in the same manner as organic latent image carrier P1, except that a bisazo pigment was used as the carrier generating substance and a hydrazone derivative was used as the carrier transporting substance. This is referred to as [organic latent image carrier P2J].

(3) Organic latent image carrier P3 An organic latent image carrier formed in the same manner as organic latent image carrier P1 except that a bis71 pigment was used as a carrier generating substance and a styryl triarylamine M derivative was used as a carrier transporting substance. was configured. This is referred to as "organic latent image carrier P3J."

01↑1, Wa0.7・' Actual photo test〉 (1) Test 1 (Actual photo test under room temperature environmental conditions) Organic latent image carrier, magnetic brush developer, corona to form a negative charge latent image An electrophotographic copying device comprising a corona transfer device that generates electric discharge and a cleaning device having a cleaning blade made of urethane rubber.
Using a modified Bix155ONRJ (manufactured by Konishiroku Photography Co., Ltd.), a live-action test was conducted to form an image on an organic latent image carrier at 80,000 yen under room temperature environmental conditions of 20°C and 50% relative humidity. The following items were evaluated.

In each Example and Comparative Example, the developer used is as shown in Table 2 above.

In addition, in the above-mentioned live-action test, other developing conditions were as follows. That is, the surface potential (highest potential) of the organic latent image carrier when it is charged is -500V, the magnet roll is a rotating type and the magnetic flux density on the surface of the developing sleeve is 800 μs, and the direction of movement of the organic latent image carrier and the developing sleeve is -500V. are in the same direction, the ratio of the peripheral speed of the organic latent image carrier to the peripheral speed of the developing sleeve is 1:2, and the DC bias voltage applied to the developing sleeve is -150V.

The results are shown in Table 3 below.

(2) Fog The fogging was determined by measuring the relative density of a white background portion with an original MAR degree of 0.0 with respect to a copied image using a "Sakura Densitometer" (manufactured by Konishiroku Photo Industry Co., Ltd.). Note that the white background reflection density was set to 0.0. For evaluation, when the relative concentration was less than 0.01, it was defined as rOJ, when it was 0.01 or more and less than 0.03, it was defined as "Δ", and when it was 0.03 or more, it was defined as rXJ.

(2) 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 to the copied image.

0 image quality copy image, image dropout, image disturbance, image sweeping, gradation,
Visual judgment was made from five viewpoints of sharpness. Evaluation,
rOJ is good when it is good, "Δ" is when it is slightly bad but at a practical level, and "x" is when it is bad and has a practical problem.

"Image dropout" refers to the phenomenon in which part of the image is missing, and "image disturbance" refers to the phenomenon of irregular shading differences in the entire image and toner adhering to the periphery of the image. "Eye" refers to the phenomenon in which a linear difference in shading appears in an image.

■Resolution In accordance with JIS Z 4916, equally spaced horizontal lines per 11 blades are 4.0, 5.0, 6.3, and 8.0.
Using a chart provided with a book, the resolution was displayed as a blade with discernible horizontal lines.

(2) Transfer rate After the transfer process, it was calculated by measuring the weight of the toner transferred to the transfer paper and the weight of the toner remaining on the organic latent image carrier.

■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 there is some toner scattering, but it is at a practical level, mark it as "Δ."
'', cases where a large amount of toner scattering was observed and were problematic in practice were designated as rXJ.

■Cleanability After repeatedly forming an image, the surface of the organic latent image carrier was visually observed immediately after being cleaned with a cleaning blade, and the judgment was made based on the presence or absence of deposits on the surface of the organic latent image carrier. . The evaluation is ``○'' if there are almost no deposits observed and the product is in good condition, "Δ" if some deposits are observed but at a practical level, and "Δ" if a lot of deposits are observed and it is considered problematic for practical use. The case was marked as “×”.

(2) Test 2 (live photo test under high humidity environment conditions)
) A live photo test was conducted in the same manner as Test 1, except that the environmental conditions were a high temperature of 33°C and a relative humidity of 85%.
As can be understood from the results in the table, according to the developer of the present invention, in the developing process, the negative charge latent image formed on the organic latent image carrier by the magnetic brush development method is fogged, image omissions occur, and the image It is possible to achieve development with good gradation and resolution without scuffing, toner scattering, or a decrease in image density.
It is possible to transfer at a high transfer rate without deteriorating gradation or resolution, and in the cleaning process, it can be cleaned well using a cleaning blade with a simple structure.As a result, fogging, image dropout, It is possible to form a clear image with high image density, good gradation, and resolution without image disturbance, image sweeping, or fringing.

Further, even when performing the image forming process many times, it is possible to stably form a good image.

In addition, good images can be stably formed many times even in high-temperature environments.

In addition, Examples 4 and 5 give better results in terms of vorticity than Comparative Examples, but the gradation and resolution of Examples 4 and 5 are inferior, and the surface treatment of silica fine particles requires amino acid treatment. Rather than the modified silane coupling agent and silicone oil, the same amino-modified silicone oil,
This indicates that silicone rubber and silicone resin are preferred.

It is clear from the table that the comparative examples have many practical problems compared to the above examples.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of an electrostatic image developing apparatus that can be suitably used to carry out development using the developer of the present invention. 10-11-8! Latent image carrier 10^--Conductive support 10B--Photosensitive 7@tt-m-Developing sleeve 12--Magnet roll 13--One regular blade 17--Developer layer (magnetic brush) 18 --1 DC bias power supply

Claims (1)

[Claims] Coated carrier, non-magnetic toner, positively charged silica particles and
A negatively charged latent image developer containing an oxide powder of a group IV_a element.