JPH0566601A - Developer and image forming method - Google Patents

Abstract

PURPOSE:To provide the developer and the image forming method which obviates the generation of toner fusion on a photosensitive body, can form a high-density image free from fogging, hardly contaminates a contact electrifying device with the toner and does not generate uneven electrification even in the event of the contamination. CONSTITUTION:This developer is constituted by sticking inorg. powder having the ternary amino group expressed by formula (I) (where R5 and R6 denote the same or different substituents; the total of the carbon atoms of R5 and R6 is >=2) on the surface and having >=10 hydrophobing degree in a test for the degree of wetting with water to the surface of toner particles consisting of at least a charge control agent, a magnetic material having >=5% hydrophobing rate and a binder resin. This image forming method consists in having an electrifying stage for electrifying a body 1 to be electrified by bringing an electrifying member 2 into contact with this body and impressing a voltage E thereto from the outside and a developing stage using the developer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to electrophotography, electrostatic recording,
The present invention relates to a developer and an image forming method for visualizing an electrostatic charge image in an image forming method such as electrostatic printing. More specifically, the present invention relates to a developer and an image forming method used in an electrophotographic method having a charging step in which a charging member applied with a voltage from the outside is brought into contact with a member to be charged for charging.

[0002]

2. Description of the Related Art Conventionally, a corona discharger has been known as a charging means in an electrophotographic apparatus or the like. However, the corona discharger has problems that a high voltage must be applied and that the amount of ozone generated is large. Therefore, recently, it has been considered to use the contact charging means without using the corona discharger. Specifically, the contact charging means applies a voltage to a conductive roller that is a charging member,
The roller is brought into contact with a photosensitive member, which is a member to be charged, to charge the surface of the photosensitive member to a predetermined potential. By using such a contact charging means, the voltage can be lowered and the amount of ozone generation can be reduced as compared with the conventional corona discharger. For example, in Japanese Examined Patent Publication No. 50-13661, a roller having a core metal coated with a dielectric material made of nylon or polyurethane rubber is used to enable application of a low voltage when charging the photosensitive paper.

[0003]

However, in the above-mentioned conventional example, when the cored bar is coated with nylon, it does not have elasticity like rubber, so that it is not possible to maintain sufficient contact with the body to be charged and thus charging failure occurs. There is a problem that causes. On the other hand, if the core metal is coated with polyurethane rubber, the softening agent impregnated in the rubber-based material will exude, so if a photoreceptor is used as the charged body, when the photoreceptor is stopped,
There are problems that the charging member is fixed to the photoconductor at the contact portion, and that image blurring occurs in the area where the softening agent oozes out. Also, if the softening agent in the rubber material of the charging member seeps out and adheres to the surface of the photoreceptor, the resistance of the photoreceptor decreases and image deletion occurs. The remaining toner adheres to the surface of the charging member, causing a filming phenomenon. When a large amount of toner adheres to the surface of the charging member, the surface of the charging member becomes insulated, the charging ability of the charging member is lost, and the charging of the surface of the photoconductor becomes uneven, which affects the image. This is because the charging member strongly presses the surface of the photoconductor, so that the residual developer is easily fixed to the charging member and the surface of the member to be charged, and further, scratches and scrapes easily occur.

In the contact charging device using the contact charging means described above, a DC voltage or a DC voltage superimposed with an AC voltage is applied to the charging member for use, but in the vicinity of the contact portion between the charging member and the photosensitive drum. , Especially because the residual developer with a small particle size and light weight is repeatedly charged and fluctuated repeatedly, unlike the case of using the conventional non-contact charging means with a corona discharger, especially the surface of the charging member or the photosensitive drum. It is easy to electrostatically attract or embed the residual developer in the toner. On the other hand, in recent years, small and inexpensive personal-use copiers and laser printers have emerged. In these small machines, from the standpoint of maintenance-free, the photoconductor, developing device, cleaning device, etc. are integrated. A cartridge system that has been adopted is adopted. Further, as the developer, it is desirable to use a magnetic one-component developer because the structure of the developing device can be simplified. In such a magnetic toner, since the toner itself has a strong polishing effect, if an organic photoconductor (OPC) or the like having a low surface hardness is used, pressure contact with the photosensitive drum is likely to occur. In the image forming step, a white penetrating phenomenon caused by a developer to which an inorganic fine powder is externally added is scraped off the pressure contact member and the surface of the photoconductor,
Alternatively, there is a problem that toner is easily fused such as toner fusion and filming due to scratches on the pressure contact member and the photoconductor drum, and an image defect occurs in the worst case. Such a problem is particularly remarkable when an abutting member, such as the above-mentioned charging member, which is in contact with the surface of the photoconductor with a predetermined abutting pressure is used. In order to solve these problems, it has been proposed to treat the silica surface with silicone oil.However, although this method is effective in preventing toner fusion to the photoreceptor, white spots due to silica dust and reverse fog are observed. There is another problem that is likely to occur. Also, JP-A-58-132757
In the publication, the number of carbon atoms is 5 or more (8 in the case of having a ring structure.
Although it has been proposed to protect the photoconductor by treating it with the silane coupling agent having a substituent described above), it was not effective in preventing toner fusion to the photoconductor.

Accordingly, it is an object of the present invention to provide a novel developer and an image forming method which do not cause toner fusion on a photosensitive member and can obtain an image having a high density and no fog. Another object of the present invention is to provide an image forming method having a contact charging step and a developing step, in which a contact charging device is less likely to be contaminated with toner, and even if contaminated, a charging unevenness is not generated and an image forming method. To provide.

[0006]

The above object can be achieved by the present invention described below. That is, according to the present invention, the following general formula (I)

[Chemical 2] (In the formula, R ₅ and R ₆ represent the same or different substituents, and the total number of carbon atoms of R ₅ and R ₆ is 2 or more.), And have a tertiary amino group and are wet with water. In this test, an inorganic fine powder having a hydrophobicity of 10 or more is adhered in a degree test, and an image forming method using the developer.

[0007]

Preferred Embodiment A contact charging step applicable to the image forming method of the present invention will be specifically described. FIG. 1 is a schematic configuration diagram of a contact charging device that is an embodiment to which the image forming method of the present invention is applied. In the figure, reference numeral 1 denotes a photoconductor drum which is a member to be charged, and an organic photoconductor (OPC) 1b which is a photoconductor layer is provided on an outer peripheral surface of a drum base la made of aluminum.
And is rotated at a predetermined speed in the direction of the arrow. For example, in this embodiment, the outer diameter of the photosensitive drum 1 is 30 mmφ. Further, 2 is the photosensitive drum 1
Is a charging roller that is a charging member brought into contact with a predetermined pressure on a metal cored bar 2a with a conductive rubber layer 2b and a surface layer 2c as a releasable coating around the metal cored bar 2a. There is. At this time, it is preferable that the surface layer 2c is a releasable coating film in terms of matching with the developer and the image forming method according to the present invention. However, if the resistance of the release film is too large, the photosensitive drum 1 is not charged, while if the resistance is too small, a large voltage is applied to the photosensitive drum 1 and the drum is damaged and pinholes occur. Therefore, it is preferable to have an appropriate resistance. That is, volume resistivity 1
It is preferable to have a resistance of about 0 ⁹ to 10 ¹⁴ Ωm,
Further, the thickness of the releasable coating is preferably within 3.0 μm. As the lower limit of the thickness of the releasable coating, it is considered that peeling or smearing of the coating does not occur, and about 5 μm is preferable. In this embodiment, the outer diameter of the charging roller 2 is 12 mmφ, the conductive rubber layer 2b is made of EPDM, and the surface layer 2c is made of nylon resin having a thickness of 10 μm. The hardness of the charging roller 2 was 54.5 ° (ASKER-C). Reference numeral E denotes a power supply unit that applies a voltage to the charging roller 2, and supplies a predetermined voltage to the core metal 2a of the charging roller 2. In FIG. 1, E indicates a DC voltage, but it is preferable to superimpose an AC voltage on the DC voltage. In addition, as the process conditions when the AC voltage is superimposed on the DC voltage, the following conditions are preferable. Contact pressure 5 ~ 500 g / cm AC voltage 0.5 ~ 5 KV _PP AC frequency 50 ~ 3000 Hz DC voltage -200 ~-900V

FIG. 2 is a schematic diagram showing a contact charging member of a contact charging device of another embodiment to which the image forming method of the present invention is applied. The same members as those of the apparatus shown in FIG. 1 described above are designated by the same reference numerals, and the description thereof will be omitted. The contact charging member 2'of the present embodiment is a blade-shaped member that is brought into contact with the photosensitive drum 1 in the forward direction with a predetermined pressure. In this blade 2 ′, a conductive rubber 2 ′ b is supported by a metal supporting member 2 ′ a to which a voltage is supplied, and a surface layer 2 ′ that serves as a releasable coating at the contact portion with the photosensitive drum 1. c is provided. A nylon resin having a thickness of 10 μm was used as the surface layer 2'c. According to this embodiment, the blade 2
There is no problem such as adhesion between the ‘and the photosensitive drum 1,
The same effects as those of the above-described embodiment are obtained.

The above-mentioned embodiments are mere examples, and a roller-shaped or blade-shaped charging member is used, but the charging member is not limited to this, and the present invention can be implemented with other shapes. .. Further, in the above-mentioned embodiments,
The charging member is composed of a conductive rubber layer and a release film, but not limited to this, a high resistance layer for preventing leakage to the photoreceptor between the conductive rubber layer and the release film surface layer, for example, an environment. It is also a preferred embodiment to form a hydrin rubber layer with small fluctuation. As the release coating, PVDF (polyvinylidene fluoride) or PVDC (polyvinylidene chloride) may be used instead of the nylon resin. As a photoconductor,
Amorphous silicon, selenium, ZnO, etc. can also be used. In particular, when amorphous silicon is used for the photoconductor, compared to the case where other materials are used, if the softening agent of the conductive rubber layer adheres to the photoconductor even a little, the image flow becomes worse. The effect due to the formation of the insulating coating on the surface becomes large.

Further, when the image forming method of the present invention is applied, in the cleaning step, the photosensitive drum after the toner image transfer, which is generally performed, is transferred by a cleaning member such as a cleaner blade or roller. A method is used in which a toner surface and other contaminants are wiped and removed to obtain a clean surface and the image is repeatedly formed. Such a cleaning step can also be performed at the same time in the charging step, the developing step, or the transfer step related to electrophotography. The image forming method of the present invention is particularly effective for an image forming apparatus in which the surface of the latent image carrier is an organic compound. This is because when the organic compound forms the surface layer, it has good adhesiveness to the binder resin contained in the toner, and thus promotes toner fusion. In particular, when a material of the same quality as the binder resin is used, a chemical bond is generated at the contact point, and toner fusion is promoted.

As the surface material of the latent image carrier used in the image forming method of the present invention, for example, silicone resin, vinylidene chloride, ethylene-vinyl chloride, styrene-acrylonitrile, styrene-methyl methacrylate, styrene,
Examples thereof include polyethylene terephthalate and polycarbonate. However, the present invention is not limited to these, and other monomers or copolymers or blends between the exemplified resins can be used. The image forming method of the present invention is particularly effective for an image forming apparatus in which the latent image carrier has a diameter of 50 mmφ or less. This is because in the case of a small-diameter drum, even if the linear pressure is the same, the curvature is large and the pressure is likely to concentrate at the abutting portion. Further, it is considered that the same phenomenon occurs in the belt photoreceptor, and the image forming method of the present invention is effective for an image forming apparatus having a radius of curvature of 25 mm or less at the transfer portion.

Next, the developer according to the present invention will be specifically described. The developer according to the present invention has a hydrophobicity of 5% or more,
Preferably, 8% or more of a magnetic material is used. By making the magnetic material hydrophobic as described above, it is possible to suppress the increase of the adhesive force to the charging member and the surface of the photoconductor due to the moisture adsorption of the developer, and at the same time, reduce the friction between the surface of the photoconductor and the developer, thereby reducing the Can be prevented and toner fusion can be prevented. As the magnetic fine particles used in the developer according to the present invention, substances that are magnetized when placed in a magnetic field are used.
For example, powders of ferromagnetic metals such as iron, cobalt and nickel, or alloys and compounds such as magnetite, γ-Fe ₂ O ₃ and ferrite can be used. The BET specific surface of these magnetic fine particles by the nitrogen adsorption method is preferably 1 to
20 m ² / g, more preferably from 2.5~12m ² / g, further, magnetic powder having a Mohs' hardness of 5 to 7 is preferred. The content of such magnetic powder is 1 with respect to the weight of the toner.
It is preferably from 0 to 70% by weight. The hydrophobicity of the magnetic material in the present specification is measured as follows. First, put 50 cc of pure water in a 100 cc beaker and gently float the sample (1 g) on the water surface. While gently stirring, add alcohol (ethanol) with a buret. At this time, the tip of the buret should be placed under the water surface so that the alcohol does not directly hit the magnetic powder. The amount of alcohol dripped x (cc) is read with the end point where most of the magnetic powder has settled, and the hydrophobicity is calculated from the following formula.

[Formula 1] Further, it is preferable that this hydrophobicity is not detached from the surface of the magnetic material even after the magnetic material is washed with toluene.

Further, the inorganic fine powder contained in the developer according to the present invention has the following general formula (I) on the surface:

[Chemical 3] (In the formula, R ₅ and R ₆ represent the same or different substituents,
The total number of carbon atoms of R ₅ and R ₆ is 2 or more). Furthermore, preferably, the oxidation potential is 800 m, which is represented by the following formula.
Inorganic fine powder treated with a tertiary aminosilane coupling agent having V or less is preferable.

[Chemical 4] (In the formula, R ₁ represents an alkoxy group, and R ₂ and R ₃ are
The same or different groups, an alkoxy group, an alkyl group or an aryl group, R ₄ represents an alkylene group or a phenylene group, R ₅ and R ₆ are the same or different groups,
An alkyl group or an aryl group is shown. However, the alkylene group or the phenylene group may have an amino group. )
Further, the hydrogen atom contained in R ₄ may be substituted with halogen to such an extent that the positive chargeability of the treated silica fine powder is not adversely affected. R ₁ , R ₂ and R ₃ are preferably a group having 1 to 4 carbon atoms, R ₄ is preferably a group having 2 to 10 carbon atoms, R 1
₅ and R ₆ are preferably a group having 2 to 12 carbon atoms.

Specifically, for example, it is treated with the following aminosilane coupling agent.

[Chemical 5]

[Chemical 6]

[Chemical 7]

[Chemical 8]

[Chemical 9]

[Chemical 10]

In the constitution of the developer of the present invention, it is not preferable that the inorganic fine powder in the developer is separated from the toner particles from the viewpoint of damaging the photoreceptor. Further, a material having low charge controllability or poor dispersibility is not preferable because it easily damages the photoconductor and easily causes fusion of the toner on the photoconductor surface. Therefore, the silica fine powder contained in the developer of the present invention has an oxidation potential of 800 mV or less (preferably 700 mV).
It is preferably treated with the following aminosilane coupling agent). When the oxidation potential exceeds 800 mV, the treated silica has insufficient chargeability,
In particular, toner fusion is likely to occur under high temperature and high humidity, which is not preferable. The fine silica powder contained in the developer of the present invention preferably has a hydrophobicity of 10 or more in the water leak test. This is because when the hydrophobicity is less than 10, sufficient chargeability cannot be obtained due to the temperature absorption of silica and toner fusion is likely to occur.

Therefore, the developer of the present invention has an oxidation potential of 8
When the silica fine powder treated with aminosilane having an amino group at the end of the aminosilane coupling agent of 00 mV or less and a tertiary amine is used, the developer is sufficiently satisfactory in hydrophobicity and chargeability, and It can provide good image quality and durability when used mixed with a toner. The treatment of the silica fine powder as described above can be performed, for example, as follows. While vigorously agitating the silica fine powder while heating as necessary, spray or vaporize and spray the treatment agent or its solution onto the silica fine powder, or make the silica fine powder into a slurry and stir it. Surface treatment can be performed by dropping a treatment agent or a solution thereof. Furthermore, about 50 to 350 thereafter
It is preferable to perform heat treatment at a temperature of ° C.

As the silica fine powder which is an inorganic fine powder constituting one component of the developer of the present invention, silica fine powder produced by a dry method or a warm method can be used. At this time, the fine silica powder produced by the dry method is preferable because it is finer and has higher fluidity than the silica produced by the warm method. The dry method referred to here is a method for producing fine silica powder produced by vapor phase oxidation of a silicon halogen compound. For example,
There is a method of utilizing a thermal decomposition oxidation reaction of silicon tetrachloride gas in an oxyhydrogen flame, and the basic reaction formula is as follows. SiCl ₄ + 2H ₂ + O ₂ → SiO ₂ + 4HCl In this manufacturing process, for example, aluminum chloride,
Alternatively, by using another metal halogen compound such as titanium chloride together with a silicon halogen compound, it is possible to obtain a composite fine powder of silica and another metal oxide, and these are also included.

As a method for producing the silicic acid fine powder used in the present invention by a wet method, various conventionally known methods can be applied. For example, it is the decomposition of sodium silicate by an acid, and the reaction formula is shown below. Na ₂ O ・ XSiO ₂ + HCl + H ₂ O → SiO ₂・ nH ₂ O + NaCl Decomposition with ammonium salts or alkali salts of sodium silicate, after generating alkaline earth metal silicate from sodium silicate, then decomposing with acid There are a method of making silicic acid, a method of making a sodium silicate solution into silicic acid by an ion exchange resin, a method of using natural silicic acid or a silicate, and the like. The silica fine powder mentioned here includes anhydrous silicon dioxide (silica), other aluminum silicate,
Any of silicates such as sodium silicate, potassium silicate, magnesium silicate and zinc silicate can be applied.

[0019] Of the above fine silica powder, the specific surface area by nitrogen adsorption measured by the BET method of 30 m ² / g or more (in particular in the range of 50 to 400 m ² / g), give good results. The "oxidation potential" defined in the specification of the present invention is measured as follows. That is, the sample electrode and the counter electrode are platinum electrodes, the reference electrode is a saturated calomel electrode, and 0.1N n-tetrabutylammonium perchloride is used as the supporting electrolyte for the measurement. Of course, it is possible to apply other measuring methods while referring to the measuring method in the present invention. A solvent that can dissolve each sample compound was selected and used each time. The developer of the present invention using the silica fine powder treated with the aminosilane coupling agent having an oxidation potential of 800 mV or less by such a measuring method has sufficient chargeability, environment resistance and tribo stability. Is excellent in terms of.

Further, in the present invention, silica fine powder treated with an aminosilane coupling agent having a hydrophobicity of 10 or more in water leakage can be preferably used. The "water leakage degree" here is obtained by the following test. That is, 1.0 g of the silica fine particles to be tested is collected in a 200 ml separating funnel, and 100 ml of ion-exchanged water is added with a measuring cylinder. Next, set the separatory funnel on the Turbula shaker mixer TC2 type and set it to 90 rpm.
Dispersion for 10 minutes. Then, the separating funnel is removed from the Turbula shaker mixer model T2C and left to stand for 10 minutes. Then, after extracting 20 to 30 ml from the separating funnel, it is fractionated into a 10 mm cell. Using ion-exchanged water as a blank (transmittance 100%), a colorimeter was used, and a wavelength of 5
The turbidity of the water layer at 00 nm is measured. The reading value (transmittance T%) at this time is defined as the water leak rate. However, if all the silica leaks to the water, the water leak rate is set to 0.

The tribo value of the silica fine particles used in the developer of the present invention is measured by the following method. That is, 25
The silica fine powder left to stand overnight in an environment of 50 ° C. and 60% RH is mixed with an iron powder carrier having a particle size of 200/300 mesh at a ratio of 2:98. 0.5-1.5 g of the mixture is precisely weighed and 25 cmH on a metal 400 mesh screen connected with an electrometer.
_The tribo charge amount is determined per unit weight by the weight of the silica fine powder particles separated and sucked at that time and the amount of charge thereof. In the present invention, the triboelectric charge amount measured by the above method is +100 μc / g
Surface-treated silica fine particles of +500 μc / g are preferably used in the developer of the present invention. Further, when the applied amount of these silica fine particles is 0.05 to 10 parts by weight with respect to 100 parts by weight of the toner, the effect is exhibited, and particularly preferably, it is excellent when 0.1 to 3 parts by weight is added. It is possible to provide a developer exhibiting positive stability and stability. In addition, if a preferable aspect of the addition form is described,
It is preferable that 0.01 to 1 part by weight of the treated silica fine powder with respect to the weight of the developer is attached to the surface of the toner particles.

As the charge output control agent contained in the developer of the present invention, there are nigrosine, triphenylmethane dyes, quaternary ammonium salts and the like, and nigrosine is particularly preferable from the viewpoint of ensuring chargeability. Usually, a developer containing a nigrosine-based dye and hydrophobic magnetic fine particles tends to be difficult to clean from the photoreceptor due to too strong charging property especially at low temperature and low humidity, but in the developer according to the present invention, Since the inorganic fine powder having a primary amino group on the surface adheres to the surface of the toner particle, cleaning is easy even at low temperature and low humidity, and fusion of the photoreceptor does not easily occur even in an image forming apparatus having a contact charging device. ..

As the binder resin used in the developer of the present invention, the following binder resin for toner can be used when a heating and pressure roller fixing device having a device for applying oil is used. For example, polystyrene, poly-p-chlorostyrene, homopolymers of styrene such as polyvinyltoluene and substitution products thereof; styrene-p-chlorostyrene copolymer styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, Styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-
Vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isopropylene copolymer, styrene-acrylonitrile-
Styrene-based copolymers such as indene copolymers; polyvinyl chloride, phenol resins, natural resin-modified phenol resins,
Natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin,
Epoxy resin, xylene resin, polyvinyl butyral,
Terpene resin, coumarone indene resin, petroleum resin, etc. can be used. In the heating and pressure roller fixing method in which oil is hardly applied, when a part of the toner image on the toner image supporting member is transferred to the roller, so-called offset phenomenon and adhesion of the toner to the toner image supporting member are important problems. Is. Toners that are fixed with less heat energy usually have a property of easily blocking or caking during storage or in a developing device, and therefore these problems must be taken into consideration at the same time. Preferred binder materials include crosslinked styrenic copolymers or crosslinked polyesters.

Examples of the comonomer of the styrene-based copolymer with respect to the styrene monomer include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, and acrylic. Phenyl acid, methacrylic acid, methyl methacrylate, ethyl methacrylate,
A monocarboxylic acid having a double bond such as butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide, etc. or a substitution product thereof;
For example, a dicarboxylic acid having a double bond such as maleic acid, butyl maleate, methyl maleate, dimethyl maleate and the like, and substituted products thereof; vinyl esters such as vinyl chloride, vinyl acetate, vinyl benzoate and the like; Ethylenic olefins such as ethylene, propylene, butylene, etc .; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, etc .; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, etc. These vinyl monomers are used alone or in combination of two or more. As the cross-linking agent, a compound having two or more polymerizable double bonds is mainly used. For example, aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene, etc .; for example, ethylene glycol diacrylate, ethylene glycol dimethacrylate. Carboxylic acid ester having two double bonds such as 1,3-butanediol dimethacrylate and the like; divinyl compounds such as divinylaniline, divinyl ether, divinyl sulfide and divinyl sulphon; and 3 or more vinyl groups Are used alone or as a mixture. When the pressure fixing method is used, a binder resin for pressure fixing toner can be used, and examples thereof include polyethylene, polypropylene, polymethylene, polyurethane elastomer, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer. Polymer,
Ionomer resin, styrene-butadiene copolymer, styrene-isoprene copolymer, linear saturated polyester,
There are paraffin, etc.

The developer of the present invention may be mixed with various additives as required. As the colorant, conventionally known dyes and pigments can be used, and the binder resin 1 is usually used.
You may use 0.5-20 weight part with respect to 00 weight part. Further, the magnetic developer of the present invention may optionally contain an external additive such as a lubricant such as zinc stearate, an abrasive such as cerium oxide or silicon carbide, or a fluidity such as silica fine powder or aluminum oxide. It is also one of the preferred embodiments of the present invention to add an agent, an anti-caking agent, or a conductivity-imparting agent such as carbon black or tin oxide. For the purpose of improving the releasability at the time of heat roll fixing, a wax-like substance such as low molecular weight polyethylene, low molecular weight polypropylene, microcrystalline wax, carnauba wax, sazol wax, paraffin wax, etc. is added in an amount of about 0.5 to 5 wt%. This is also one of the preferable modes of the present invention. In the production of the developer according to the present invention, after well kneading the constituent materials with a heat kneader such as a heat roll, a kneader, an extruder, mechanical pulverization, a method of obtaining by classification, or a material in a binder resin solution Is obtained by dispersing and then spray-drying, or a polymerization method for obtaining a toner by emulsifying or suspending in a solution by mixing a predetermined material with a monomer to form a binder resin and then polymerizing the mixture. Each method such as a toner manufacturing method can be applied.

[0026]

EXAMPLES The present invention will now be described in more detail by way of examples, which should not be construed as limiting the invention.
In the following formulation, all parts are parts by weight. Example 1-Styrene-n-butyl acrylate copolymer 100 parts (copolymerization weight ratio 8: 2, Mw = 250,000) -Magnetic fine powder whose surface was treated with a titanium coupling agent (hydrophobicity 10%) 90 Parts-Nigrosine 3 parts-Low molecular weight polypropylene 3 parts The above mixture was melt-kneaded in a twin-screw extruder, and the cooled kneaded material was coarsely crushed with a hammer mill and then finely crushed,
Wind power classification was performed to obtain a magnetic particle classification powder (toner) (I) having a weight average particle diameter (D ₄ ) of 7.0 μm. Silica fine powder (I) treated with dimethylaminopropyltrimethoxysilane (BET 130 m ² / g) was added to this toner (I) in an amount of 1.4% based on the weight of the toner, and the mixture was mixed with a Henschel mixer to obtain the developer of the present invention ( I) was obtained. Next, the magnetic developer thus prepared was subjected to a DC voltage (-650V) and an AC voltage (-650V) in the charging device by using an image forming method (FC-1 modified machine manufactured by Canon) having a contact charging device shown in FIG. 300Hz, 1
700 Vpp) is applied, and a test of continuously copying at a printing speed of 6 sheets (A4) / minute is performed at a constant temperature and a constant humidity (23.
The image was evaluated at 5 ° C. and 60 RH. At the same time, the states of the charging member and the surface of the photosensitive drum were observed, and fusion was evaluated by a solid black image.

FIG. 1 shows a schematic view of a roller type charging member.
Table 1 shows the characteristics of the silica fine powder used. Also, Table 2
Shows the evaluation result of the fusion test after continuous printing of 3000 sheets. However, the evaluation criteria are as follows. Fusing of photoconductor (evaluation by the number of white spots in A4 solid black image) ○ ... No fusion at all ○ △… Fusion of 1 to 3 points in A4 solid black △… 3 to 10 points in A4 solid black Fusing x: Fusing 10 points or more in A4 solid black

Example 2 As a magnetic material, 110 parts of a magnetic material having a surface treated with palmitic acid (hydrophobicity 15%) was used, and silica was used.
A developer (II) was prepared and evaluated in the same manner as in Example 1 except that the silica fine powder (II) shown in 1 was used. The evaluation results are shown in Table 2.

Example 3 A developer (III) was prepared in the same manner as in Example 1 except that a triphenylmethane dye was used instead of nigrosine and the silica fine powder (III) shown in Table 1 was used as silica. And evaluated. The evaluation results are shown in Table 2.

Example 4 A developer (IV) was prepared in the same manner as in Example 1 except that the silica fine powder (IV) shown in Table 1 was used as silica. Further, evaluation was performed in the same manner as in Example 1 except that the developer (IV) was used and the blade type charging member shown in FIG. 2 was used. The evaluation results are shown in Table 2.

Comparative Example 1 As in Example 1 except that untreated magnetic fine powder (hydrophobicity 0%) was used as the magnetic substance and untreated silica fine powder (V) shown in Table 1 was used as the silica. A developer (V) was prepared in the same manner. The evaluation results are shown in Table 2.

[0032]

[Table 1] Table 1

[0033]

[Table 2] Table 2

[0033]

As described above, the developer of the present invention has a hydrophobicity of 5
% Magnetic fine powder and silica fine powder having a specific tertiary amino group on the surface of the developer, the toner melts on the surface of the photoreceptor even when applied to an image forming apparatus having a contact charging device. You can obtain high-quality and fog-free images without causing wear.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a contact charging device that is an embodiment to which an image forming method of the present invention is applied.

FIG. 2 is a schematic configuration diagram of a contact charging device that is another embodiment to which the image forming method of the present invention is applied.

[Explanation of symbols]

 1: photoconductor drum 2, 2 ': charging member E: power supply

Front Page Continuation (72) Inventor Hirohide Tanigawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (2)

[Claims] 1. A toner represented by the following general formula (I) on the surface of a toner comprising at least a charge control agent, a magnetic material having a hydrophobicity of 5% or more, and a binder resin. (In the formula, R ₅ and R ₆ represent the same or different substituents,
The total carbon number of R ₅ and R ₆ is 2 or more. ), Which has a tertiary amino group and has an inorganic fine powder having a hydrophobicity of 10 or more in a water wettability test adhered thereto. 2. An image forming method comprising: a charging step of bringing a charging member into contact with a member to be charged and applying a voltage from the outside to perform charging, and a developing step using the developer according to claim 1. ..