JPH03100662A - Positively charging developer and image forming method - Google Patents

Abstract

PURPOSE:To prevent the surface of a developer carrying member from receiving nonuniform polishing by incorporating a toner and fine powder subjected to a surface treatment with amino modified silicone oil into a developer. CONSTITUTION:A film 10 contg. conductive fine particles is formed on the surface of the developer carrying member 2 which comes into contact with the developer 5, deposits the developer on the surface and transports the same to a developing region formed between the member and an electrostatic latent image carrying member 1. The developer 5 contains the toner and the fine powder subjected to the surface treatment with the amino modified silicone oil. Namely, the fine particles existing on the surface of the developer play the role of the lubricant between the developer 5 and the developer carrying member 2. The pressing of the developer, the generation of flaws on the surface of the developer carrying member or sticking of the developer thereto is prevented in this way even if the developing operations are repeatedly carried out. The performance of the coated sleeve is thus sufficiently utilized.

Description

[Detailed Description of the Invention] [Technical Field] The present invention is utilized in the field of technology for developing electrostatic latent images with a developer, and particularly relates to an image forming method in which development is performed by restraining a developer with magnetic force, and an image forming method therefor. Regarding the developer used.

[Prior art]

Conventionally, for example, a developing device that visualizes a latent image formed on the surface of a photosensitive drum as an electrostatic latent image carrier using magnetic toner as a one-component developer has been developed using friction between magnetic toner particles and the developer. Friction between the sleeve as a carrier and the magnetic toner particles gives the magnetic toner particles an electric charge of opposite polarity to the electrostatic image charge formed on the photosensitive drum. There is a known device in which the electrostatic latent image on the photosensitive drum is visualized by transporting the toner to a developing area formed by a sleeve and causing the magnetic toner to fly under the action of a magnetic field from a magnet fixed in the sleeve. ing.

[Problem to be solved by the invention]

However, in all of the above-mentioned developing devices, it is necessary to form a relatively thin and uniform toner layer on the sleeve, but it depends on the environmental conditions, toner physical properties, sleeve surface condition, etc. This often results in unevenness, especially in low-humidity environments.

In addition, as the developer is repeatedly rubbed against the sleeve as copies are made, non-developing substances such as additives to improve toner fluidity and carriers in two-component toners may accumulate on the sleeve, or during development. The surface condition of the sleeve changes because the binder resin in the agent forms a film on the sleeve, making the developing performance of the developer unstable or the conveyance of the developer to the electrostatic latent image surface unstable. There was a problem of becoming

In order to prevent such changes in the surface condition of the sleeve,
For example, one that forms a film containing an inorganic polymeric carbon fluoride (Japanese Patent Laid-Open No. 57-66443), and one that forms a resin with good mold release properties in which silica is dispersed (Japanese Patent Laid-Open No. 58-66443).
178380), an organic silicone polymer, an aliphatic fluorine-containing compound, a styrene resin, and a polyphelalene oxide, and a coating containing a metal complex having a di- to hexadentate ligand. (Japanese Unexamined Patent Publication No. 57-76558) has been proposed in which the surface of the sleeve is coated with a material having particularly high mold releasability to prevent changes in the surface condition.

However, these coated sleeves in which synthetic resin or the like is coated on the sleeve surface are clearly softer than sleeves made of conventionally used aluminum or SUS. Therefore, while performing repeated development operations,
The developer is pressed against the surface, which is especially noticeable in the case of magnetic developers containing magnetic materials, and the surface of the developer carrier may be unevenly polished or scratched, or some of the developer may be damaged. There was a problem in that the inherent performance of the coat sleeve was likely to deteriorate due to adhesion of the coated sleeve.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a positively chargeable developer that can be uniformly carried on the surface of a sleeve, and an image forming method using the developer.

[Summary of the invention]

The present invention provides conductive fine particles on the surface of a developer carrier that contacts the developer in a developer storage chamber, carries the developer on the surface, and transports the developer to a development area formed between the electrostatic latent image carrier and the developer storage chamber. A positively charging developer used in a developing device in which a film containing The present invention relates to a positively chargeable developer and an image forming method using the developer.

[Detailed description of the invention]

Hereinafter, a developing device used in the present invention will be explained based on the accompanying drawings.

FIG. 1 is a sectional view of an example applied to a developing device used in the present invention.

1 in the figure is a photosensitive drum as an electrostatic latent image carrier that carries an electrostatic latent image and rotates in the direction of arrow A. Either one with or without an insulating layer on the surface can be used. Of course, the shape is not limited to a drum shape, but also a sheet shape or a belt shape. 2 carries toner 5 on the surface and arrow B
The sleeve 2 serves as a developer carrier that rotates in the direction , and a multipolar permanent magnet 3 is fixed inside the sleeve 2 so as not to rotate. Further, on the surface of the sleeve 2, a coating 10 containing conductive particles, which will be described later, has a thickness of about 0.5 μm.
It is formed to have a thickness of ~30 μm. Reference numeral 4 denotes a developer storage chamber that stores the toner 5 and brings the toner 5 into contact with the surface of the sleeve 2 . Reference numeral 6 denotes a doctor blade as a member that regulates the layer of toner 5 on the surface of the sleeve 2 carried in the developer storage chamber 4 to a predetermined thickness, and the gap between the surface of the sleeve 2 and the doctor blade 6 is about 50 μm to The thickness is 500 μm.

The developing device configured as described above starts and the sleeve 2
When rotates in the direction of arrow B, in the developer storage chamber 4, due to contact friction between the toners 5 or between the surface of the sleeve 2 and the toner 5, charges of opposite polarity to the electrostatic latent image on the photosensitive drum l are applied to the toner 5. and applied to the surface of the sleeve 2.

The toner layer applied to the sleeve surface is further coated into a uniform and thin layer (layer thickness is approximately 30 μm) by a doctor blade 6 disposed opposite to one magnetic pole (S pole in the figure) of the multipolar permanent magnet 3. ~300 μm),
The photosensitive drum 1 and the sleeve 2 form a developing area. Furthermore, by applying an AC bias between the sleeve 2 and the surface of the photosensitive drum 1 in the development area, the toner 5 on the sleeve 2 may be caused to fly toward the photosensitive drum.

Here, the coating 10 formed on the sleeve surface will be explained.

The film io used is one in which the film-forming polymeric material contains conductive fine particles.

As the conductive fine particles, carbon fine particles, carbon fine particles and crystalline graphite, or crystalline graphite are preferable.

The crystalline graphite used in the present invention can be roughly divided into natural graphite and artificial graphite. Artificial graphite is produced by solidifying pitch coke with tar pitch, etc., firing it once at about 1200℃, putting it into a graphitization furnace, and treating it at a high temperature of about 2300℃, which causes carbon crystals to grow and turn into graphite. . Natural graphite is produced from underground after being completely graphitized by natural geothermal heat and high underground pressure over a long period of time. These graphites have various excellent properties and have a wide range of industrial uses. Graphite is
It is a very soft and slippery crystalline mineral with a dark gray or black luster. It is used in pencils, etc. Due to its low heat resistance and chemical stability, it is used as a powder or solid in lubricants, fire resistance, electrical materials, etc. It is used in the form of paint. The crystal structure includes hexagonal crystals and rhombohedral crystal structures, and has a completely layered structure. Regarding electrical properties, free electrons exist between carbon and carbon bonds, making it a good conductor of electricity. Note that the graphite used in the present invention may be either natural or artificial.

Furthermore, the graphite used in the present invention has a particle size of 0.5 μm.
-” 10 μm is preferable.

Examples of film-forming polymeric materials include thermoplastic resins such as styrene resins, vinyl resins, polyethersulfone resins, polycarbonate resins, polyphenylene oxide resins, polyamide resins, fluororesins, cellulose resins, and acrylic resins, and epoxy resins. Thermosetting resins or photocurable resins such as resins, polyester resins, alkyd resins, phenol resins, melamine resins, polyurethane resins, urea resins, silicone resins, and polyimide resins can be used. Among them, those with mold release properties such as silicone resins and fluororesins, or those with excellent mechanical properties such as polyether sulfone, polycarbonate, polyphenylene oxide, polyamide, phenol, polyester, polyurethane, and styrene resins are more preferable. .

Conductive amorphous carbon is generally defined as "an aggregate of crystallites formed by burning or thermally decomposing a hydrocarbon or carbon-containing compound in an insufficient supply of air." In particular, it has excellent electrical conductivity, and is widely used because it can be filled into polymeric materials to impart electrical conductivity, and it is possible to obtain a desired electrical conductivity to some extent by controlling the amount added. The conductive amorphous carbon particles used in the present invention preferably have a diameter of 10 μm to 80 μm, more preferably 15 μm to 40 μm.

Next, the positively chargeable developer according to the present invention will be explained.

The positively charging developer of the present invention contains fine powder treated with amino-modified silicone oil or amino-modified silicone resin, and its form is such that the fine powder is dispersed on the surface of the developer. is preferred.

The developer according to the present invention has the above-described structure, so that even if repeated development operations are performed, the developer is not pressed against the surface of the developer carrier, and the surface of the developer carrier is not scratched or adhered to the developer. This makes it possible to fully utilize the original performance of the coat sleeve. That is, the developer according to the present invention is a developer that matches extremely well with the image forming apparatus according to the present invention and allows the image forming apparatus to be fully utilized, and the developer according to the present invention and the image forming apparatus are compatible. An image forming method that can provide good images has been established.

The present inventors believe that the reason for this is that fine particles present on the developer surface act as a lubricant between the developer and the developer carrier. It is presumed that the impact of contact between the fine particles and the developer carrier may be softened by treatment with modified silicone oil.

The particle size of the fine powder used in the present invention is preferably in the range of 0.001 to 2μ, particularly preferably 0.005 to 0.2μ.

The material of the fine powder used in the present invention is preferably an inorganic compound.

For example, metal oxides of Group 3 and Group 4 such as silicic acid, alumina, and titanium oxide are preferred. In particular, dry silica produced by vapor phase oxidation of silicon halogen compounds is preferred. Further, during production, it may be oxidized in a vapor phase together with a metal compound such as aluminum chloride or titanium chloride to form a composite fine powder of silica and metal oxide.

In the present invention, as the amino-modified silicone oil used to treat the fine powder, a silicone oil having a residue represented by the formula (I) can generally be used.

(Here, Rl + R6 represents hydrogen, an alkyl group, an aryl group, or an alkoxy group, and R2 is an alkylene group,
It represents a phenylene group, R3 represents a compound having a nitrogen-containing heterocycle in its structure, and R4*R5 represents hydrogen, an alkyl group, or an aryl group. Also, R2 may be (may be).

However, the above alkyl groups, aryl groups, alkylene groups,
The phenylene group may contain an amine, or may have a substituent such as a halogen within a range that does not impair chargeability. Further, m is a number of 1 or more, and n and It are positive numbers including 0. However, n+1 is a positive number of 1 or more. ) A preferred structure for the above structure is one in which the number of nitrogen atoms in the side chain containing nitrogen atoms is 1 or 2.

As the nitrogen-containing unsaturated heterocycle, poly(later) is known, and an example thereof is given below.

Further, an example of a nitrogen-containing saturated heterocycle is listed below.

However, the present invention is not limited to the above examples of compounds, but compounds having a 5-membered or 6-membered heterocycle are preferred.

In addition, as derivatives, all known derivatives such as vinyl groups, mercapto groups, methacrylic groups, glycidoxy groups, ureido groups, etc. can be used as long as they do not interfere with the charge control properties of hydrocarbon groups, halo groups, amino groups, etc. and their derivatives can be used.

Further, the nitrogen atom equivalent of the silicone oil used in the present invention is preferably io, ooo or less, and 300 to 200.
0 is preferred. The nitrogen atom equivalent here is the equivalent per nitrogen atom (g/eqio), which is the value obtained by dividing the molecular weight by the number of nitrogen atoms per molecule.

These may be used alone or in a mixed system of two or more.

Known techniques can be used as a method for silicone oil treatment. For example, mixing fine powder and amino-modified silicone oil using a mixer, spraying amino-modified silicone oil into fine powder using a sprayer, or dissolving amino-modified silicone oil in a solvent and then mixing fine powder. Examples include, but are not limited to, the following.

Examples of the silicone varnish used to obtain the amino-modified silicone varnish for fine powder treatment used in the present invention include methyl silicone varnish, phenylmethyl silicone varnish, and the like, with methyl silicone varnish being particularly preferred.

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

[M31 unit] CH3 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 (1) %Formula% (R#I represents a methyl group or a phenyl group) In the above silicone varnish, the T'' unit in particular imparts good thermosetting properties and forms a three-dimensional network structure. Fine particles whose surfaces are treated with silicone varnish containing such T" units have a hard and tough film on their surfaces, which improves impact resistance, moisture resistance, and mold release properties. It will be excellent. The above-mentioned T'' units are present in the silicone varnish in an amount of 10 to 90 mol%, especially 30 to 80 mol%.
It is preferably contained in a proportion of mol%. When the proportion of the T'' unit is too small, the adhesive becomes soft and the tackiness increases, and the stability of moisture resistance, durability, and triboelectric charging properties may decrease, and in particular, the cleaning performance of the developer decreases. In addition, toner scattering may occur, resulting in image unevenness, fogging, etc., and furthermore, the durability of the fixing device may be reduced.On the other hand, when the proportion of the T'' unit is excessive, toner particles may be formed on the surface of the inorganic fine particles. The coating layer may become non-uniform, and the stability and durability of triboelectric charging properties may deteriorate.

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, the T" unit, the D" unit,
A part of the methyl group or phenyl group present in the M'' unit may be replaced with a group having an amino group. Examples of the group having an amino group include those shown by the following structural formula, It is not limited to these.

-C12CH, -NH2 -CH2(CH2)2-NH2 -CH2(CH2)2-NH-(CH2), -NH2be)-NH2 BepcH2-NH2 The amino-modified silicone varnish treatment methods include oil treatment and The same known techniques can be used.

The processing amount of the solid content of the amino-modified silicone oil or amino-modified silicone varnish of the present invention is preferably 3 to 50 parts by weight, more preferably 5 to 40 parts by weight, based on 100 parts by weight of the fine powder. If the amount of treatment is less than that, the surface of the fine powder cannot be sufficiently coated, and the moisture resistance will not be improved. If the processing amount is larger than that, aggregates of fine powder will be formed, and the dispersion and addition to the toner will be insufficient.

The above-mentioned treated fine powder exhibits an effect when added in an amount of 0.05 to 3 parts by weight per 100 parts by weight of the developer, and particularly preferably exhibits excellent stability when added in an amount of 0.1 to 2 parts by weight. have If the amount is less than 0.05 parts by weight, no effect will be observed, and if it exceeds 3 parts by weight, development problems will occur, which is not preferable.

In the present invention, examples of the binder resin for the toner include polystyrene and poly-p-chlorostyrene.

Monopolymers of styrene and its substituted products such as polyvinyltoluene; styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylic acid methyl copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer Polymer, styrene-butyl methacrylate copolymer, styrene-α-methyl chloromethacrylate copolymer, styrene-acrylonitrile copolymer,
Styrene-vinyl methyl ether copolymer, styrene-
Styrenic copolymers such as vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer; styrene-dimethylamino ethyl acrylate copolymer,
Styrenic aminoacrylic-containing copolymers such as styrene-diethylaminoethyl acrylate copolymer and styrene-butyl acrylate-diethylaminoethyl methacrylate copolymer; polyvinyl chloride, polyvinyl acetate, polyethylene.

Polypropylene, silicone resin, polyester.

Epoxy resin, polyvinyl butyral, rosin.

Modified rosin, terpene resin, phenolic resin, xylene resin, aliphatic or alicyclic hydrocarbon resin.

Aromatic petroleum resins, chlorinated paraffins, paraffin waxes, etc. may be used alone or in combination.

Further, as coloring materials that can be added to the developer according to the present invention, conventionally known carbon black, copper phthalocyanine,
Iron black etc. can be used.

The developer according to the present invention may contain a magnetic material.

The magnetic fine particles contained are materials that are magnetized when placed in a magnetic field, such as iron and cobalt.

Powder of ferromagnetic metal such as nickel or magnetite, γ-Fe203. Alloys and compounds such as ferrite can be used.

These magnetic fine particles preferably have a BET specific surface area of 2 to 20 rr? determined by the nitrogen adsorption method. /g, especially 2.5-1
2 rrr/g, and preferably a magnetic powder having a Mohs hardness of 5 to 7. The content of this magnetic powder is 10% of the amount of toner.
~70% by weight is good.

Further, the developer of the present invention may contain a charge control agent if necessary, and positive charge control agents such as nigrosine dye and ammonium tetrasalt salt are used.

The developer of the present invention may further include other additives, such as Teflon, lubricants such as zinc stearate, fixing aids (such as low molecular weight polyethylene), or conductivity imparting agents, as long as they do not have a substantial adverse effect. Alternatively, a metal oxide such as tin oxide may be added.

In producing the developer of the present invention, a hot roll is used.

After thoroughly kneading the constituent materials using a thermal kneader such as a Ni-Goo or an extruder, the material can be obtained by mechanical crushing or classification, or after dispersing the material in a binder resin solution.
A method for producing toner by spray drying, or a polymerization method for obtaining a developer (toner) by mixing a specified material with a monomer to form a binder resin to form an emulsified suspension and then polymerizing it. , each method can be applied.

Specific examples will be described below, but the present invention is not limited to the following examples. Note that all parts on each side are parts by weight.

After uniformly mixing the above materials, they were kneaded, pulverized, and classified to obtain a positively chargeable toner having an average particle size of about 11 μm.

Next, 20 parts of amino-modified silicone oil with an amine value of 700 was used as a processing agent for 100 parts of silicic acid (average particle size: 0.016 μ, BET specific surface area 130 rrr/g) to obtain a treated fine powder. 0 for 100 parts of toner
．． A positively chargeable developer was obtained by externally adding 7 parts.

Using this developer and a commercially available copying machine FC-5 (manufactured by Canon), the surface of the developer carrier was coated with a synthetic resin containing conductive graphite particles in a ratio of l=1 to phenol resin. The image quality was evaluated by changing the film to a film with a film thickness of 7 μm.

As a result, normal temperature and humidity (20°C, 60% Rh), high temperature and high humidity (32°5°C, 90% Rh), low temperature and low humidity (15°C,
Even under an environment of 10% Rh), it was possible to obtain good images without environmental anomalies and without sleeve memory.

Furthermore, while replenishing toner, an image quality evaluation was performed on 5,000 sheets, and good images with no problems could be obtained. Further, no toner adhesion or scratches were observed on the surface of the developer carrier.

Appearance 1" The silicic acid fine powder of Example 1 was mixed with α-alumina (average particle size 0,
020 μ, BET 100 ni'/g), and the same treatment was carried out to obtain a treated fine powder.Otherwise, the same developer as in Example 1 was obtained, and image formation was performed.

As a result, after sheets a and ooo, there was a slight decrease in density compared to Example 1, but it was at a level with no problem. 5
No toner adhesion or scratches were observed on the surface of the developer carrier after printing ,000 images.

A treated fine powder was obtained by treating the silicic acid fine powder of Example 1 with 4 parts of amino-modified silicone oil having an amine value of 700, and the same developer as in Example 1 was obtained, and image forming was carried out. I did it.

As a result, similar to Example 1, a good image was obtained. Further, although slight scratches were found on the surface of the developer carrier after 5,000 images were printed, they were at a non-problematic level that did not affect the images.

As described above, in the present invention, the positively chargeable developer according to the present invention can be used in an image forming method using a developing device having a developer carrier on the surface of which a film containing conductive particles is formed. Accordingly, it is possible to prevent the occurrence of scratches on the surface of the developer carrier, prolong the life of the developer carrier, and provide a good image that is not dependent on the environment.

Developer carrier (sleeve) multipolar permanent magnet Developer storage chamber doctor blade coating Ru.

Claims (2)

[Claims] (1) Conductive fine particles are applied to the surface of the developer carrier that contacts the developer in the developer storage chamber, carries the developer on its surface, and transports it to the development area formed between it and the electrostatic latent image carrier. A positively chargeable developer used in a developing device in which a film containing the toner is formed, the developer containing toner and fine powder surface-treated with amino-modified silicone oil or amino-modified silicone varnish. Characteristic positively charging developer. (2) Conductive fine particles are applied to the surface of the developer carrier that contacts the developer in the developer storage chamber, carries the developer on its surface, and transports it to the development area formed between it and the electrostatic latent image carrier. In an image forming method in which an electrostatic latent image is developed using a developing device in which a film containing the electrostatic latent image is formed, a developer containing fine powder whose surface has been treated with a toner and amino-modified silicone oil or amino-modified silicone varnish is used to develop the electrostatic latent image. An image forming method characterized by developing an electrostatic latent image.