JP3203425B2 - Two-component magnetic developer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-component developer using a toner and a carrier, and more particularly to a two-component developer using a magnetic toner containing magnetic fine particles and a carrier.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. Sho 53-33152 discloses a prior art relating to a two-component developer using a magnetic toner.
JP-A-56-11140 discloses a two-component developer using a magnetic toner in combination with a carrier containing magnetic powder in a thermoplastic resin or wax.

However, a carrier containing magnetic powder in a thermoplastic resin is difficult to contain a sufficient amount of magnetic powder in the carrier to restrain the carrier on a developer-carrying magnetic sleeve. The carrier is easily detached from the developer-carrying magnetic sleeve, and the detached carrier adheres to the photosensitive drum and is collected by the cleaner portion, so that the carrier is consumed and the mixing ratio of the toner and the carrier is kept constant. And it is difficult to maintain a stable image for a long period of time.

Further, US Pat. Nos. 4,609,603 and 4,695,524 and JP-A-61-141451 disclose a toner containing magnetite and a carrier obtained by coating a ferrite core or a steel core with a resin. Are disclosed.

In the above specification, it is important to add 0.1 to 1% by weight of colloidal silica such as Aerosil R972 or equivalent as a fluidity imparting agent to the toner surface. It has been disclosed.

Colloidal silica such as Aerosil R972 or equivalent is silica that is easily triboelectrically charged to a negative polarity. Therefore, when used as a developer for developing a positively charged latent image, that is, a toner having a negatively charged polarity, the toner has fluidity. As well as contribute to maintaining the quality of the developer stably over a long period of time.

[0007] However, Aerosil R972
When a colloidal silica such as or a colloidal silica is added to a developer for developing a negatively charged latent image, that is, a toner having a positive charge polarity, a sufficient amount of silica is added to impart fluidity to the toner. Since the triboelectric charging polarity is opposite, the triboelectric charging ability of the positively charged polar toner is reduced,
Even if mixed with a carrier, a sufficient amount of triboelectric charge is not obtained, and the electrostatic attraction due to triboelectric charging between the toner and the carrier is weakened. As a result, the toner is easily separated from the carrier surface, and the There is a disadvantage that a so-called fogging phenomenon in which toner adheres to a portion having no electrostatic latent image, that is, a background portion, is likely to occur.

Further, since the magnetic two-component developer contains magnetic fine particles in the toner, the abrasive power is higher than that of the conventional non-magnetic two-component developer toner, and it is long. When copying is repeated, fine scratches are easily made on the photosensitive drum. This is particularly remarkable in the case of an organic semiconductor OPC whose surface layer is made of an organic substance and has a low surface hardness. When the degree of scratches worsens, the toner adheres to the surface and strongly adheres to the surface of the photoreceptor and is removed by the cleaning unit. The toner remains on the surface of the drum without being charged, and the portion of the drum to which the toner adheres during the next copying process is exposed to electric charge, so that the toner is developed in the developing section, and this appears on the copied image. Had.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a two-component developer for developing a negatively charged latent image which solves the above-mentioned problems.

Specifically, the objects of the present invention are as follows: (1) the mixing ratio of the toner and the carrier does not change for a long time; (2) the frictional charging ability between the toner and the carrier is sufficient; and (3) no fog. Magnetic particles are uniformly dispersed in the toner. (5) When used in a copier printer with a low speed of 4 cpm to a high speed of 135 cpm, an offset phenomenon does not occur even if silicone oil is not applied to the fixing roller of the fixing device ( 6) An object of the present invention is to provide a two-component developer in which the surface of the photoreceptor is hardly damaged even when copying is repeated for a long period of time.

[0011]

The present invention relates to a two-component developer comprising a toner, a carrier and an additive,
Positive toner containing at least a binder resin and 10 to 60% by weight of the magnetic fine particles, and polyolefin-based polymer
It is a magnetic toner having a charged polarity , a carrier is a ferrite core or a steel core coated with a resin, and additives are inorganic fine particles coated with a nitrogen-containing compound and fine particles of a frictional resistance reducing substance having an average particle diameter of 0.05 to 1 μm. And a two-component magnetic developer.

Hereinafter, the present invention will be described in detail.

When the magnetic fine particles are contained in the binder resin of the toner at a ratio of 10 to 60% by weight based on 100% by weight of the toner, not only the electrostatic attraction due to the triboelectric charging between the toner and the carrier, but also the developer carrying sleeve has Since the force of attracting the toner to the carrier surface is exerted by the magnetic field of a certain permanent magnet, the toner is less likely to separate from the carrier surface and so-called fogging is less likely to occur as compared with a toner containing no magnetic fine particles in the toner.

Of course, the fogging phenomenon cannot be prevented only by the force of attracting the toner to the carrier surface due to the magnetic field of the permanent magnet in the developer carrying sleeve. A prerequisite is that the electrostatic attraction works sufficiently.

The magnetic fine particles contained in the binder resin of the toner may be any material which exhibits magnetism or is magnetizable. Examples thereof include metal magnetites such as iron, manganese, nickel, cobalt, and chromium, hematite, and various ferrites. , Manganese alloys, and other ferromagnetic alloy fine particles, and those having an average particle size of 0.05 to 5 μm, more preferably 0.1 to 2 μm are preferable.

The content of the magnetic fine particles contained in the toner binder resin is 10 to 60% by weight, preferably 15 to 40% by weight in the toner. When the content of the magnetic fine particles is 10
When the amount is less than 10% by weight, the magnetic field of the permanent magnet in the developer carrying sleeve has an insufficient force to attract the toner to the carrier surface and is not effective in preventing fogging. The magnetic field of the permanent magnet in the sleeve attracts the toner to the surface of the carrier due to an excessively strong force. At the time of development, the toner is separated from the surface of the carrier by the electric field formed by the electrostatic latent image on the photosensitive drum to develop the electrostatic latent image. Since the power is weakened, the image density to be developed becomes low.

Examples of the binder resin for the toner used in the present invention include styrene such as polystyrene, poly p-chlorostyrene, and polyvinyl toluene, and a homopolymer of a substituted product thereof;
Styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-
Methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer Coalesce, styrene-butyl methacrylate 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-based copolymers such as styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester copolymer; polymethyl methacrylate , Polybutyl methacrylate,
Polyvinyl chloride, polyvinyl acetate, polyester, polyurethane, polyamide, epoxy resin, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, phenol resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum Resins, chlorinated paraffins, and the like can be used alone or in combination of two or more.

As the coloring material used in the toner, conventionally known carbon black, iron black and the like can be used, and all the conventionally known dyes as positive charge control agents can be used in the present invention. For example, various dyes such as benzyldimethyl-hexadecylammonium chloride, decyl-trimethylammonium chloride, nigrosine, nigrosine base, nigrosine hydrochloride, safranin γ and crystal violet.

The polyolefin polymer used in the toner of the present invention is a polymer containing an olefin monomer as a monomer component in an amount of preferably at least 50 mol%, more preferably at least 60 mol%. Examples thereof include a polymer, an ethylene-vinyl acetate copolymer, an ethylene-ethyl acrylate copolymer, and an ionomer having a polyethylene skeleton.

The core material of the carrier that can be used in the present invention is a ferrite core or a steel core of 10 to 10.
A resin having a core surface of 150 μm, preferably 30 to 100 μm, coated with a resin of 0.1 to 10 μm, preferably 0.5 μm to 2.0 μm is good. If the thickness of the coating layer is less than 0.1 μm, the core surface cannot be uniformly coated with the resin, so that it is not possible to sufficiently prevent the toner from being spent on the carrier surface. On the other hand, if it exceeds 10 μm, it is difficult to prevent aggregation of the core particles in the step of coating the carrier surface with the resin. On the other hand, if the core particle size is less than 10 μm, it is difficult to prevent the carrier from adhering to the surface of the photoreceptor, and if it exceeds 150 μm, the magnetic brush ears formed by the developer become coarse and the solid portion of the original is reproduced. Is difficult. Ferrite core, or as a resin for coating the steel core, styrene-methyl methacrylate copolymer, methyl methacrylate polymer,
Styrene-butadiene copolymer, silicone resin, fluororesin and the like can be used.

In order to prevent the so-called spent phenomenon in which the toner physically adheres to the carrier surface while the developer is used for a long time, a silicone resin or a fluororesin which is a low surface energy substance is used alone or It is preferable to use together with another resin.

For the purpose of controlling the electric resistance of the resin-coated carrier, the resin coating layer of the carrier may contain carbon black, conductive zinc oxide, conductive tin oxide, conductive titanium oxide, and metal powder.

The inorganic fine particles used as one of the additives in the present invention include silicon dioxide fine particles, titanium oxide fine particles and zinc oxide fine particles whose surfaces are coated with a nitrogen-containing compound. The surface of which is coated with a nitrogen-containing compound is particularly preferred.

The silicon dioxide fine particles have a BED surface area of 15
0 to 300 (m^Two / G) is good.

Such silicon dioxide fine particles are so-called dry silica or fumed silica, and are manufactured by a conventionally known technique. For example, it utilizes the 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 +4
HCl, for example, in this production step, it is also possible to obtain a composite fine powder of silica and other metal oxides by using another metal halide such as aluminum chloride or titanium chloride together with a silicon halide,
They are also included.

The average particle size of the particles is 0.0%.
It is desirable to be within the range of 01 to 2 μm, and it is particularly preferable to use silica fine powder within the range of 0.002 to 0.2 μm.

Commercially available silica fine powder produced by vapor phase oxidation of a silicon halide used in the present invention includes, for example, those commercially available under the following trade names. AEROSIL 130 (Nippon Aerosil) 200 300 380 TT600 MOX80 MOX170 COK84 Ca-O-SiL M-5 (CABOT Co.) MS-7 MS-75 HS-5 EH-5 Wacker (Vucker) HDK N20 V15 (WACKER-CHEEMIE N20E (Vacker Kemi) GMBH) T30 T40 DC Fine Silica (Fine silica) (Dow Corning Co.) Fransol (Fransol) (Fransil (Fransil)) Nitrogen-containing coating on the surface of inorganic fine particles As the compound, a silicone oil having an amine in a side chain is particularly preferable. A silane coupling agent containing an amino group can also be used in the present invention.

As the silicone oil having an amine in the side chain, generally, a silicone oil containing a structural unit represented by the formula (1) can be used.

[0029]

Embedded image (Where R ₁ represents hydrogen, an alkyl group, an aryl group or an alkoxy group, R ₂ represents an alkylene group or a phenylene group, and R ₃ and R ₄ represent a hydrogen, an alkyl group or an aryl group. , An aryl group, an alkylene group, or a phenyl group may contain an amine, or may have a substituent such as halogen as long as the chargeability is not impaired.) As the silicone oil, for example, there is an amino-modified silicone oil represented by the following structural formula, which is preferable.

[0030]

Embedded image (Here, R ₁ and R ₅ represent an alkyl group or an aryl group, R ₂ represents an alkylene group or a phenylene group or an alkyl group containing an amine, and R ₃ represents a hydrogen, an alkyl group, or an aryl group. n is a number of 1 or more.) Specifically, the following are preferable, and these may be used alone or in a mixture of two or more. The amine equivalent in the table means the equivalent (g / eqi) per amine group.
v. ) Is the value obtained by dividing the molecular weight by the number of amines per molecule. Particularly, those having an amine equivalent of 25,000 or less are preferred, and those having an amine equivalent of 5,000 or less are particularly preferred.

The following are commercially available products having an amine group in the side chain.

Trade name Viscosity at 25 ° C. Amine equivalent (cps) SF8417 (manufactured by Toray Silicone Co., Ltd.) 1200 3500 KF393 (manufactured by Shin-Etsu Chemical Co., Ltd.) 60 360 KF857 (〃) 70830 KF859 (〃) 60 22500 KF860 (〃) 250 7600 KF 861 (〃) 3500 2000 KF 862 (〃) 750 1900 KF864 (〃) 1700 3800 KF 865 (〃) 90 4400 KF 369 (〃) 20 320 KF 383 () 20 320 XX 320-236-X -380D (〃) 2300 3800 X-22-3801C (〃) 3500 3800 X-22-3810B (〃) 1300 1700 Silane cup that can be used in the present invention Packaging agents are those compounds containing an amino group represented by the following such structure. _{H 2 NCH 2 CH 2 CH 2} Si (OCH 3) 3 H 2 NCH 2 CH 2 CH 2 Si (OC 2 H 5) 3

[0033]

Embedded imageH_TwoNCONHCH_TwoCH_TwoCH_TwoSi (OC_TwoH_Five)_Three H_TwoNCH_TwoCH_TwoNHCH_TwoCH_TwoCH_TwoSi (OCH_Three)_Three H_TwoNCH_TwoCH_TwoNH CH_TwoCH_TwoNHCH_TwoCH_TwoCH_TwoSi (OCH_Three)_Three H_FiveC_TwoOCOCH_TwoCH_TwoNHCH_TwoCH_TwoCH_TwoSi (OCH_Three)_Three H_FiveC_TwoOCOCH_TwoCH_TwoNHCH_TwoCH_TwoNHCH_TwoCH_TwoCH_TwoSi (OCH_Three)_Three H_FiveC_TwoOCOCH_TwoCH_TwoNHCH_TwoCH_TwoNHCH_TwoCH_TwoNHCH_TwoCH_TwoNH ・ CH_TwoCH_TwoCH_TwoSi (OCH_Three)_Three H_ThreeCOCOCH_TwoCH_TwoNHCH_TwoCH_TwoNHCH_TwoCH_TwoCH_TwoSi (OCH_Three)_Three

[0034]

Embedded imageH_ThreeCNHCH_TwoCH_TwoCH_TwoSi (OC_TwoH_Five)_Three H_TwoN (CH_TwoCH_TwoNH)_TwoCH_TwoCH_TwoCH_TwoSi (OCH_Three)_Three H C-NHCONHC_ThreeH₆Si (OCH_Three)_Three And the like. Further, the alkoxy group of the above compound is
It may be a chlorine atom. These silane couplings
The agents may be used alone or in a mixture of two or more.

The treatment amount of the nitrogen-containing compound coated on the inorganic fine particles is 0.01 to 30% by weight, more preferably 0.5 to 20% by weight, based on the inorganic fine particles.

The additive amount of the additive to the toner is 0.01
To 2.0% by weight, preferably 0.1 to 1.0% by weight.

In the production of the toner, materials such as a binder resin, magnetic fine particles, and an olefin polymer are uniformly mixed, and then the constituent materials are kneaded well by a heat kneader such as a hot roll, kneader, extruder, or the like. A method obtained by mechanical pulverization and classification, or a method obtained by dispersing a material such as a magnetic powder in a binder resin solution and then spray-drying, or a method in which a monomer constituting the binder resin is Each method can be applied, such as a polymerization toner production method in which materials are mixed to form an emulsion suspension and then polymerized to obtain a magnetic toner.

[0038] As the frictional drag reducing material particles which can be used in the present invention, zinc stearate, calcium stearate, metal soap fine particles, such as aluminum stearate, tetrafluoroethylene particles, vinylidene fluoride fine particles, and the like, the average particle also diameter of 0.05~1μ
Is used. In particular , vinylidene fluoride fine particles having an average particle diameter of 0.1 to 0.5 μm are preferably added to the toner in an amount of 0.01 to 2.0% by weight.

As a method of coating the surface of the carrier with a resin, a resin solution for coating the carrier is sprayed onto the carrier core while keeping the carrier core suspended in hot air using a fluidized bed such as a Wurster type. A resin coating layer can be provided on the carrier surface by wiping the resin solution on the surface and removing the solvent of the resin solution with hot air.
If necessary, the surface of the carrier may be baked at 100 ° C. to 400 ° C. after the resin coating to increase the film strength.

To coat the surface of the inorganic fine particles with the nitrogen-containing compound, for example, put the inorganic fine powder in a heated hermetically sealed Henschel mixer, stir and float the inorganic fine powder in the Henschel mixer. The solution can be coated by spraying a solution of the compound onto the surface of the inorganic fine powder and then removing the solvent of the attached solution by hot-air drying.

[0041]

EXAMPLES Production Example 1 100 parts by weight of a styrene-2 ethylhexyl acrylate copolymer (monomer weight ratio 85:15), iron trioxide 2
5 parts by weight, 4 parts by weight of polypropylene, Nigrosine dye 2
Parts by weight were mixed with a Henschel mixer, and then heated and melt-kneaded with a roll mill. After cooling, the resultant was coarsely ground by a hammer mill, finely ground by a supersonic jet mill, and classified by an air classifier to obtain a toner having a weight average of 9.0 μm and a number average of 7.5 μm.

Production Example 2 Wurster type fluidized air bed (fluidized a
spherical ferrite powder 1 having an average particle size of 75 μm
000 parts by weight, under a hot air atmosphere of 85 to 90 ° C,
While the ferrite powder is suspended in the air, a silicone resin SR-2411 (manufactured by Toray Silicone) is added to the ferrite powder.
Was sprayed with 400 parts by weight of a 5% toluene solution, and the surface of the ferrite powder was coated with a silicone resin. The suspension of the silicone resin-coated ferrite powder in air was continued to be dried with hot air to remove toluene. After removing the toluene, the silicone resin-coated ferrite powder was taken out from the Wurster-type fluidized air bed and baked in an electric furnace at 200 ° C. for 2 hours.
What was left in the air and cooled naturally to room temperature was used as a carrier.

Production Example 3 Silica fine particles Aerosil in a Henschel mixer
200 (BED surface area 200m^Two / G) 100 parts by weight
Preparation, in a hot atmosphere of 200 ℃, in the air silica fine particles
Silicone with amine group in side chain while suspended in
Oil (amine equivalent 3800; viscosity at 25 ° C 1
700 cps) Spray 15 parts by weight and continue stirring for 30 minutes
In this way, the surface of the silica fine particles contains amine in the side chain.
Silica fine particles coated with silicone oil.

Production Example 4 1000 parts by weight of spherical iron powder having an average particle size of 90 μm were charged into a Wurster-type fluidized air bed, and while this spherical iron powder was suspended in the air, Teflon S (Du'pont) was added thereto. A product prepared by diluting 200 parts by weight of epoxy-modified Teflon enamel with 200 parts by weight of methyl ethyl ketone (MEK) was sprayed in a hot atmosphere at 45 to 50 ° C., and the surface of the spherical iron powder was coated with Teflon enamel.

After the application, the spherical iron powder coated with Teflon enamel was kept suspended in the air, and MEK was removed with hot air at 45 to 50 ° C.

The spherical iron powder coated with Teflon enamel was taken out from the Wurster-type fluidized air bed, baked in an electric furnace at 300 ° C. for 2 hours, left in air, and naturally cooled to room temperature to obtain a carrier.

Example 1 100 parts by weight of the toner of Production Example 1, 0.5 parts by weight of silica of Production Example 3, and 0.5 parts by weight of vinylidene fluoride fine particles having an average particle diameter of 0.3 μm were mixed with a Henschel mixer for 1 minute. With stirring, silica and vinylidene fluoride fine particles were adhered to the toner surface. 3 parts by weight of this toner and 97 parts by weight of the carrier of Production Example 2 were stirred with a V-type mixer for 1 minute to obtain a developer.

The amount of triboelectric charge of this developer is defined as B. S
Hein, J.A. Appl. Phys. Vol 46,
No. 12 Dec. page 5140 (197
When measured by the blow-off method described in 5), 1
It was 8 μc / g.

This developer was used in a Canon copier NP483.
The copying machine of No. 5 was remodeled for a two-component developer, and copying of 300,000 sheets was repeated.

When the obtained copied image is observed with an optical reflection microscope, the characters faithfully reproduce the original document, there is no scattering of toner around the characters, and toner adheres to the non-image portion, so-called There was no fog, and the solid portion was uniformly covered with the toner, and a high quality image without unevenness was obtained. Its quality is unchanged from the beginning to the end of 300,000 copies, and its image density is 5mmφ.
The image measured with a Macbeth densitometer showed that a high density image of 1.5 was obtained from the beginning of repetitive copying until the end of 300,000 copies.

Further, no silicone oil was applied to the Teflon roller of the fixing unit during the repetitive copying of 300,000 sheets, but no offset occurred at the beginning and end, and the toner was fused to the Teflon roller. Did not. After repeating 300,000 sheets, the developer after copying was taken out and measured by a blow-off method, which was 17 μc / g, which was substantially the same as the initial value. When the toner concentration was measured, it was 3.1%
It was also found that this had not substantially changed.

The OPC drum after the endurance of 300,000 sheets was taken out and the surface was observed, but no damage was found on the surface, which was not different from the initial stage of the endurance.

Example 2 100 parts by weight of the toner of Production Example 1 and silica of Production Example 3
0 parts by weight and 0.05 parts by weight of vinylidene fluoride fine particles having an average particle diameter of 0.1 μ were stirred with a Henschel mixer to attach silica and vinylidene fluoride fine particles to the toner surface. 4 parts by weight of the toner and 96 parts by weight of the carrier of Production Example 4 were stirred with a V-type mixer for 1 minute to obtain a developer.

The amount of triboelectric charge of this developer was measured by a blow-off method and found to be 28 μc / g.

This developer was used in a Canon copier NP483.
Using the developing device No. 5 modified for a two-component developer, 300,000 sheets were repeatedly copied.

The image obtained was of high quality and high in image density as in Example 1. The quality did not change at the beginning and after the end of 300,000 repeated copying, and the triboelectric charge amount and toner concentration also changed substantially. Did not.

While 300,000 sheets were repeatedly copied, silicone oil was not applied to the roller of the fixing device, but no offset occurred and no fusion to the Teflon roller occurred.

Further, the OPC drum after 300,000 sheets of durability were taken out and the drum surface was observed, but no damage was found on the drum surface, and there was no change from the initial stage.

Comparative Example 1 The developer was adjusted in the same manner as in Example 1 except that the vinylidene fluoride fine particles were not added to the toner of Example 1, and the developing unit of the Canon NP4835 copying machine was subjected to two-component development. When repeated copying was carried out in a modified product, scratches started to form on the drum surface at around 50,000 sheets, and the degree of scratches became worse as the number of sheets increased.

Comparative Example 2 A developer was prepared in the same manner as in Example 1 except that the vinylidene fluoride fine particles were not added to the toner of Example 2.

This developer was used in a Canon copier NP483.
When the developing section No. 5 was remodeled for a two-component developer and repeated copying was performed, scratches started to be generated on the drum surface from around 70,000 sheets, and the degree of scratches became worse as the number of sheets increased.

Example 3 100 parts by weight of the toner of Production Example 1, 0.5 parts by weight of silica of Production Example 3, and 0.5 parts by weight of tetrafluoroethylene fine particles having an average particle diameter of 0.2 μm were mixed with a Henschel mixer for 1 minute. With stirring, silica and tetrafluoroethylene fine particles were attached to the toner surface. 3 parts by weight of the toner and 97 parts by weight of the carrier of Production Example 2 were stirred with a V-type mixer for 1 minute to obtain a developer.

When the triboelectric charge amount of this developer was measured, it was 16 μc / g.

This developer was used with a Canon copier NP483
When the developing unit of No. 5 was remodeled for a two-component developer and repeated copying was performed, no scratch was observed on the surface of the OPC drum up to 20 000 sheets, but the drum after 300,000 sheets Several scratches were found on the surface.

[0065]

As described above, the two-component magnetic developer of the present invention can provide a high-quality copy image for a long period without fear of damaging the photosensitive drum.

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI G03G 9/113 G03G 9/10 311 321 (56) References JP-A-3-42674 (JP, A) JP-A-63-73271 (JP, A) JP-A-63-73272 (JP, A) JP-A-62-129862 (JP, A) JP-A-63-169659 (JP, A) JP-A-2-140758 (JP, A) JP-A-62-196672 (JP, A) JP-A-2-141762 (JP, A) JP-A-61-277965 (JP, A) JP-A-61-279865 (JP, A) JP-A-2-282756 ( JP, A) JP-A-61-6665 (JP, A) JP-A-57-130050 (JP, A) JP-A-2-72373 (JP, A) JP-A-64-59360 (JP, A) (58) ) Surveyed field (Int.Cl. ⁷ , DB name) G03G 9 / 10,9 / 08

Claims (2)

(57) [Claims] 1. A two-component developer comprising a toner, a carrier and an additive, wherein the toner comprises at least a binder resin and
A positively charged magnetic toner containing 0 to 60% by weight of magnetic fine particles and a polyolefin polymer, wherein the carrier is a ferrite core or a steel core coated with a resin, and the additive is coated with a nitrogen-containing compound. A two-component magnetic developer comprising: inorganic fine particles obtained; and frictional resistance reducing substance fine particles having an average particle diameter of 0.05 to 1 μm. 2. The two-component magnetic developer according to claim 1, wherein the frictional resistance reducing substance fine particles are vinylidene fluoride fine particles.