JP4928116B2 - Replenishment developer and development method using the same - Google Patents

Description

  The present invention relates to a replenishment developer used in an electrophotographic system, an electrostatic recording system, and an electrostatic printing system, and an image forming method using the same.

  In the electrophotographic system, a uniformly charged photosensitive drum (image carrier) is subjected to image exposure to form a latent image, the latent image is developed into a toner image, and then the toner image is transferred to a recording material such as recording paper. Transcript to. When the transfer material carrying the toner image passes through the fixing device, the toner is fixed on the transfer material.

  Of the methods for developing latent images using toner, the two-component development method using a two-component developer in which toner and carrier are mixed is suitably used for a full-color copying machine or printer that requires high image quality. It has been. In the two-component development method, the carrier imparts an appropriate amount of positive or negative charge to the toner by frictional charging, and the toner is carried on the surface of the carrier by electrostatic attraction of the frictional charging. The carrier carrying the toner is supplied toward the developer carrying member (developing sleeve). The carrier carrying the toner is carried in a state where a magnetic brush is formed on the surface of the developing sleeve in which a magnet for developing and developer conveyance is provided, and the electrostatic latent image carried on the photosensitive drum. Is used for the visible image processing of the latent image.

  In the normal two-component development method, the toner in the developing device is consumed, and replenishment for the shortage is performed with new toner, but the carrier is continuously used and deteriorated, so the development characteristics deteriorate. For this reason, a maintenance work of periodically replacing the developer in the developing device occurs. In order to solve this problem, a proposal has been made that the replenishment toner and the carrier are replenished at a constant ratio, and the carrier in the developing device whose developing performance is deteriorated is gradually replaced with a new carrier so that the maintenance work is unnecessary. (For example, refer to Patent Document 1).

In recent years, copying machines and printers have been required to have higher speed and higher image quality.
In the case of a developing device having one developing sleeve, sufficient development may not be possible when developing at higher speed. This is due to the fact that the development area for the photosensitive drum is relatively narrow, so that sufficient toner cannot be developed for the latent image.

  Further, in order to reduce the size of copying machines and printers, studies have been made on reducing the diameter of the photosensitive drum. As the diameter of the photosensitive drum is reduced, the development area becomes increasingly narrow, and as a result, sufficient development may not be possible.

  As a countermeasure for these, there is a case where the linear velocity of the developing sleeve is increased with respect to the linear velocity of the photosensitive drum, for example, the linear velocity is three times or more. However, when the linear velocity of the developing sleeve is increased with respect to the photosensitive drum in this way, the amount of toner that is said to be white is reduced at the rear end or front end of the toner image on the photosensitive drum, and as a result, a part of the toner becomes white. In some cases, such an image defect portion occurs.

In order to solve such a problem, a developing device having a structure in which a plurality of developing sleeves described above are installed in parallel along the moving direction of the photosensitive drum to increase the developing area has been proposed (for example, Patent Document 2). reference).
For example, a developing device as shown in FIG. The developing device 100 shown in FIG. 1 includes a developing container 2 containing a developer, and has a plurality of sleeves (developing sleeves 8 and 11) in an opening facing the photosensitive drum 10 of the developing container 2.
In the case of such a developing device, since there are a plurality of development areas, development is sufficiently performed, and image defects such that part of the image becomes white do not occur, and high image quality can be obtained.

  However, in order to achieve high image quality, there are a plurality of developing sleeves, and in order to eliminate the need for maintenance work, replenishment toner and carrier are replenished at a constant ratio, and the carrier in the developing device has deteriorated developing performance. When using a developing device that gradually replaces the toner with a new carrier and printing at high speed, a new problem may occur.

  Since printing is performed at a high speed, the supplied replenishment developer is used for immediate development. As a result, ordinary replenishment developers are used before they are uniformly mixed, the toner charge amount becomes non-uniform, and the development characteristics may deteriorate.

  Further, for example, when the agent is transferred from the first developing sleeve 8 to the second developing sleeve 11 shown in FIG. 1, a part of the developer can be transferred to the developing sleeve 11 in order to perform printing at high speed. In other words, a phenomenon (rotation phenomenon) occurs in which the developing sleeve 8 is rotated while being attached. The developed developer is developed once by the developing sleeve 8 and consumes the toner, so that the ratio of the toner and the carrier is different from that of the other developers. For this reason, the toner charge is not constant and the image may be disturbed.

  Therefore, in order to solve such a problem, for example, a proposal has been made that a member for scraping off the developer is provided between the first developing sleeve 8 and the second developing sleeve 11 shown in FIG. However, when the developer is physically scraped in this way, a strong stress is applied to the developer at the time of scraping, the developer is deteriorated, or the surface of the developing sleeve is scratched due to the scraping member. In some cases, the characteristics deteriorated (see, for example, Patent Document 3).

For example, in the developing device 100 of FIG. 1, the developer layer thickness is kept constant by using a regulating blade (developer layer thickness regulating member) 9. In the vicinity of the regulating blade 9, the developer removed from the developing sleeve 8 by being scraped off by the regulating blade 9 tends to accumulate. The developer blade 2 is held inside the developing container 2 by the magnetic force generated by the two poles S1 and N1 of the magnet 8 ′ fixed in the developing sleeve 8. For this reason, the developer scraped off by the regulating blade 9 tends to accumulate. Further, the developing sleeve 8 rotates at a high speed for high-speed printing. Then, a great stress is applied to the developer accumulated on the regulating blade 9, and the developer is deteriorated. As a result, the image may be deteriorated.
Japanese Patent Publication No. 2-21591 JP-A-5-346737 JP 2000-155467 A

  Accordingly, an object of the present invention is to provide a developer for replenishment and an image forming method using the same for achieving high image quality and high durability in high-speed printing in which the rotation speed of the developing sleeve is 250 mm / sec or more. It is.

As a result of intensive studies by the present inventors, a developing device having at least two developer carriers in the rotation direction of the image carrier and a developer layer thickness regulating member for forming a developer layer on the developer carrier. Is used in a two-component development method in which a developer for replenishment containing at least toner and a carrier is developed while being replenished to the developing device, and the excess carrier inside the developing device is discharged from the developing device as necessary. The replenishment developer comprises a toner containing at least a binder resin and a colorant in an amount of 2 parts by weight to 50 parts by weight with respect to 1 part by weight of the carrier. The carrier has a 50% particle size (D ₅₀ ) of 15 μm or more and 70 μm or less based on the volume distribution of the carrier, the true specific gravity of the carrier is 2.5 g / cm ³ or more and 4.2 g / cm ³ or less, and 1000 / 4π ( By using a replenishment developer containing a specific toner and carrier in which the carrier has a magnetization strength of 40 Am ² / kg or more and 70 Am ² / kg or less under a magnetic field of kA / m), high speed printing is possible. It has been found that image quality and high durability can be achieved.

The above object can be achieved by the following configuration of the present invention.
(1) For replenishment containing at least two developer carriers in the rotation direction of the image carrier , a developer layer thickness regulating member for forming a developer layer on the developer carrier, toner and a carrier a developing device comprising a developer, at least, has a means for developing with replenishing the replenishment developer in the developing device, is discharged from the developing device when necessary carriers becomes excessive in the developing device In the developing device, the replenishment developer contains 2 parts by weight or more and 50 parts by weight or less of a toner containing at least a binder resin and a colorant with respect to 1 part by weight of the carrier. 50% particle size (D ₅₀ ) of 15 μm or more and 70 μm or less of the volume distribution standard of the carrier, the true specific gravity of the carrier is 2.5 g / cm ³ or more and 4.2 g / cm ³ or less, and 1000 / 4π (kA / m) under magnetic field The developing device is characterized in that the intensity of magnetization of the carrier is 40 Am ² / kg or more and 70 Am ² / kg or less.
(2) The carrier comprises a carrier core and a coating resin that coats the surface of the carrier core, and the carrier core contains a magnetic substance, or a resin and a magnetic substance. The developing device described.
(3) The developing device according to (2), wherein the carrier core is a magnetic material-containing resin carrier core in which a magnetic material is dispersed.
(4) The developing device according to any one of (1) to (3), wherein the carrier is a resin-impregnated carrier in which a porous magnetic material is impregnated with a coating resin.
(5) The product of the magnetization of the carrier and the magnetic flux density of the magnetic pole of the developer carrier closest to the developer layer thickness regulating member under a magnetic field of 1000 / 4π (kA / m) is 3000 mT · Am ² / The developing device according to any one of (1) to (4), wherein the developing device is in the range of 1 kg to 11200 mT · Am ² / kg.
(6) The ratio of the specific gravity of the two-component developer in the developing device to the specific gravity of the replenishing developer (specific gravity of the two-component developer in the developing device / specific gravity of the replenishing developer) is 1.5. The developing device according to any one of (1) to (5), wherein the developing device has a range of 3.0 or less.
( 7 ) The closest distance between the two developer carriers is not less than 15 μm and not more than 3000 μm, and the developer is delivered between the two developer carriers. ( 6 ) The developing device according to any one of ( 6 ).
( 8 ) Of the two developer carriers, the developer carrier on the upstream side of delivery of the developer has a developer layer thickness regulating member, and the developer layer thickness regulating member and the upstream developer carrier The developing device according to any one of (1) to ( 7 ), wherein the closest distance between the bodies is 100 μm or more and 3000 μm or less.

  According to the present invention, it is possible to provide a replenishment developer that can achieve high image quality, high durability, and high reliability even in high-speed printing, and an image forming method thereof.

  The replenishment developer of the present invention contains at least a toner and a carrier, and the toner contains at least a binder resin and a colorant.

The toner used in the present invention is not particularly limited as long as it contains at least a binder resin and a colorant.
As the toner binder resin, polyester; polystyrene; polymer compound obtained from styrene derivatives such as poly-p-chlorostyrene and polyvinyltoluene; styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer, Styrene-vinyl naphthalene copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ketone Styrene copolymers such as copolymers, styrene-butadiene copolymers, styrene-isoprene copolymers, styrene-acrylonitrile-indene copolymers; polyvinyl chloride; phenol resins; modified phenol resins; male resins; METAKU Polyresin resin; Polyvinyl acetate; Silicone resin; Polyester resin having a monomer selected from aliphatic polyhydric alcohol, aliphatic dicarboxylic acid, aromatic dicarboxylic acid, aromatic dialcohol and diphenol as a structural unit; Polyurethane resin; Polyamide resin; Polyvinyl butyral; Terpene resin; Coumarone indene resin; Petroleum resin.

  As the colorant used in the present invention, known dyes and / or pigments are used. A pigment may be used alone, but it is more preferable from the viewpoint of the image quality of a full-color image to improve the sharpness by using a dye and a pigment together.

For example, there are colorants as shown below.
Examples of the coloring pigment for magenta toner include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perlin compounds.
Specific examples of the color pigment for magenta toner include C.I. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 41, 48: 2, 48: 3, 48: 4, 49, 50, 51, 52, 53, 54, 55, 57: 1, 58, 60, 63, 64, 68, 81: 1, 83, 87, 88, 89, 90, 112, 114, 122, 123, 144, 146, 150, 163, 166, 169, 177, 184, 185, 202, 206, 207, 209, 220, 221, 254, C.I. I. Pigment violet 19, C.I. I. Bat red 1, 2, 10, 13, 15, 23, 29, 35, etc. are mentioned.

Examples of the magenta toner dye include C.I. I solvent red 1, 3, 8, 23, 24, 25, 27, 30, 49, 81, 82, 83, 84, 100, 109, 121, C.I. I. Disper thread 9, C.I. I. Solvent Violet 8, 13, 14, 21, 27, C.I. I. Oil-soluble dyes such as Disper Violet 1; I. Basic Red 1, 2, 9, 12, 13, 14, 15, 17, 18, 22, 23, 24, 27, 29, 32, 34, 35, 36, 37, 38, 39, 40, C.I. I. Basic violet 1, 3, 7, 1
And basic dyes such as 0, 14, 15, 21, 25, 26, 27, and 28.

Examples of the color pigment for cyan toner include C.I. I. Pigment Blue 1, 2, 3, 7, 15: 2, 15: 3, 15: 4, 16, 17, 60, 62, 66; I. Bat Blue 6, C.I. I. Examples thereof include Acid Blue 45 or a copper phthalocyanine pigment in which 1 to 5 phthalimidomethyl groups are substituted on a phthalocyanine skeleton having a structure represented by the following formula (f).

Examples of the color pigment for yellow toner include condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal compounds, methine compounds, and allylamide compounds.
Specific examples of the color pigment for yellow toner include C.I. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 16, 17, 23, 62, 65, 73, 74, 83, 93, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 155, 168, 174, 180, 181, 185, 191, C.I. I. Bat yellow 1, 3, 20, etc. are mentioned.
In addition, C.I. I. Direct Green 6, C.I. I. Basic Green 4, C.I. I. Yellow toner dyes such as Basic Green 6 and Solvent Yellow 162 can also be used.

  Examples of the black colorant include carbon black, iron oxide, and those that are toned in black using the yellow / magenta / cyan colorant shown above.

In the case of a color toner, the colorant is selected in consideration of hue angle, saturation, brightness, weather resistance, OHP transparency, and dispersibility in the toner.
The content of the colorant is preferably 0.1 to 20 parts by mass with respect to 100 parts by mass of the binder resin for toner.

The toner used in the present invention may contain a known charge control agent.
In the case of a color toner, a charge control agent that is colorless or light in color, can increase the toner charging speed, and can stably maintain a constant charge amount is particularly preferable. Furthermore, in the present invention, when a toner is produced using a polymerization method, a charge control agent that does not inhibit polymerization and has no solubilized product in an aqueous medium is particularly preferable.

Examples of the charge control agent include negative charge control agents and positive charge control agents.
Negative charge control agents include, for example, acids such as salicylic acid, dialkylsalicylic acid, naphthoic acid, dicarboxylic acid, or metal derivatives thereof; polymer compounds having sulfonic acid or carboxylic acid in the side chain; boron compounds Urea compounds; silicon compounds; and calixarenes are preferably used.
As the positive charge control agent, for example, a quaternary ammonium salt; a polymer compound having the quaternary ammonium salt in the side chain; a guanidine compound; and an imidazole compound are preferably used.
The content of the charge control agent is preferably 0.5 to 10 parts by mass with respect to 100 parts by mass of the binder resin for toner. However, the addition of a charge control agent to the toner particles is not essential.

The toner used in the present invention may contain a fluidizing agent.
Any fluidizing agent can be used as long as it can increase fluidity before and after the fluidizing agent is added to the toner.
Examples of the fluidizing agent include fluorine resin powders such as vinylidene fluoride fine powder and polytetrafluoroethylene fine powder; titanium oxide fine powder; alumina fine powder; fine powder silica such as wet process silica and dry process silica; fluorine Examples thereof include treated silica obtained by subjecting a system resin powder, titanium oxide fine powder, alumina fine powder and fine powder silica to surface treatment with a silane compound, an organosilicon compound, a titanium coupling agent, silicone oil, and the like.

A preferred dry process silica is a fine powder produced by vapor phase oxidation of a silicon halogen compound, which is called so-called dry process silica or fumed silica, and is produced by a conventionally known technique. As the dry process silica, for example, a thermal decomposition oxidation reaction in an oxyhydrogen flame of silicon tetrachloride gas is used. The basic reaction formula is the following formula (1).
(1): SiCl ₄ + 2H ₂ + O ₂ → SiO ₂ + 4HCl
In this production process, it is also possible to obtain a composite fine powder of silica and another metal oxide by using another metal halogen compound such as aluminum chloride or titanium chloride together with a silicon halogen compound. Also includes them.
The particle diameter of the dry process silica is preferably within a range of 0.001 to 2 μm as an average primary particle diameter, and particularly preferably a silica fine powder within a range of 0.002 to 0.2 μm is used. Is good.

  Examples of the titanium oxide fine powder include fine particles of titanium oxide obtained by low-temperature oxidation (thermal decomposition, hydrolysis) of sulfuric acid method, chlorine method, volatile titanium compounds such as titanium alkoxide, titanium halide, and titanium acetylacetonate. Is included. Examples of the crystalline titanium oxide fine powder include anatase type, rutile type, mixed crystal type of these, and amorphous titanium oxide fine powder.

  Examples of the alumina fine powder include a buyer method, an improved buyer method, an ethylene chlorohydrin method, an underwater spark discharge method, an organoaluminum hydrolysis method, an aluminum alum pyrolysis method, an ammonium aluminum carbonate pyrolysis method, a chlorination method. Alumina fine powder obtained by the flame decomposition method of aluminum is included. Examples of the crystalline alumina fine powder include α, β, γ, δ, ξ, η, θ, κ, χ, ρ type, mixed crystal type and amorphous alumina fine powders. Α, δ, γ , Θ, mixed crystal type, amorphous alumina fine powder is preferably used.

  More preferably, the surface of the fine powder is subjected to a hydrophobic treatment. Or it may be oil-treated.

  The method of hydrophobizing the surface of the fine powder is a method of chemically or physically treating with an organosilicon compound that reacts or physically adsorbs with the fine powder.

A preferable method for the hydrophobic treatment is a method in which silica fine particles produced by vapor phase oxidation of a silicon halogen compound are treated with an organosilicon compound.
Examples of the organosilicon compound include hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, benzyldimethylchlorosilane, Brommethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilylmercaptan, trimethylsilylmercaptan, triorganosilylacrylate, vinyldimethylacetoxysilane, dimethylethoxysilane, dimethyldimethoxy Silane, diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane, 1 , 3-diphenyltetramethyldisiloxane, and dimethylpolysiloxane having 2 to 12 siloxane units per molecule and having one hydroxyl group each in the terminal unit of Si. These are used alone or in a mixture of two or more.

  The content of the fine powder is preferably 0.8 parts by mass or more and 8.0 parts by mass or less, and 1.0 parts by mass or more and 4.0 parts by mass or less with respect to 100 parts by mass of the toner particles. More preferred.

The fluidizing agent used in the present invention has a specific surface area by nitrogen adsorption measured by BET method of 30 m ² / g or more, preferably 50 m ² / g or more from the viewpoint of fluidity imparting property.
Further, the content of the fluidizing agent is preferably 0.01 parts by mass or more and 8 parts by mass or less, more preferably 0.1 parts by mass or more and 4 parts by mass or less with respect to 100 parts by mass of the toner particles.

  As a method for producing toner particles, a binder resin, a colorant, and other internal additives are melt-kneaded, the kneaded material is cooled, pulverized and classified; a toner particle is directly generated using a suspension polymerization method. A dispersion polymerization method in which toner particles are directly generated using a monomer that is soluble in a monomer but insoluble when a polymer is formed, and an aqueous organic solvent; in the presence of a water-soluble polar polymerization initiator A method of producing toner particles by using an emulsion polymerization method represented by a soap-free polymerization method in which toner particles are directly polymerized to form toner particles; a step of agglomerating at least polymer fine particles and colorant fine particles to form fine particle aggregates and the fine particles For example, an emulsion aggregation method obtained through an aging step for causing fusion between fine particles in the aggregate.

A toner manufacturing procedure in the pulverization method will be described.
In the raw material mixing step in the pulverization method, at least a binder resin, a colorant, and, if necessary, raw materials such as a release agent are weighed and mixed as a toner internal additive and mixed. Examples of the mixing device include a double-con mixer, a V-type mixer, a drum-type mixer, a super mixer, a Henschel mixer, and a Nauter mixer.
Further, the toner raw materials blended and mixed as described above are melt-kneaded to melt the binder resin, and a colorant or the like is dispersed therein to obtain a colored resin composition. In the melt-kneading step, for example, a batch kneader such as a pressure kneader or a Banbury mixer, or a continuous kneader can be used. In recent years, single-screw or twin-screw extruders have become mainstream due to the advantage of being capable of continuous production. For example, KTK type twin screw extruder manufactured by Kobe Steel, TEM type twin screw extruder manufactured by Toshiba Machine In general, a twin-screw extruder manufactured by Kay Sea Kay, a co-kneader manufactured by Buss, or the like is used. Furthermore, the colored resin composition obtained by melt-kneading the toner raw material is rolled by a two-roll roll after melt-kneading, and then cooled through a cooling step of cooling by water cooling or the like.
In general, the cooled colored resin composition obtained above is then pulverized to a desired particle size in a pulverization step. In the pulverization step, first, coarse pulverization is performed with a crusher, a hammer mill, a feather mill or the like, and further, pulverization is performed with a kryptron system manufactured by Kawasaki Heavy Industries, Ltd., a super rotor manufactured by Nisshin Engineering Co., Ltd. or the like. After that, if necessary, classification is performed using a classifier such as an inertia class elbow jet (manufactured by Nippon Steel & Mining Co., Ltd.), centrifugal class turbo plex (manufactured by Hosokawa Micron Co., Ltd.), and the weight average particle size A classified product of 3 to 11 μm is obtained.
If necessary, it is possible to perform spheronization treatment as surface modification in the surface modification step. For example, the spheronization treatment may be performed using a hybridization system manufactured by Nara Machinery Co., Ltd. or a mechano-fusion system manufactured by Hosokawa Micron Co., Ltd., to obtain a classified product.

  When the toner particles are produced by a polymerization method, 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1 ′ is used as a polymerization initiator. -Azo-based polymerization initiators such as azobis (cyclohexane-1-carbonitrile, 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobisisobutyronitrile; benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl Peroxide-based polymerization initiators such as peroxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide are used.

  Although the addition amount of a polymerization initiator changes with the target degree of polymerization, generally 0.5-20 mass% is added and used with respect to a polymerizable monomer. Although the polymerization initiator varies slightly depending on the polymerization method, the polymerization initiator is used alone or in combination with reference to the 10-hour half-life temperature. It is also possible to add and use a known crosslinking agent, chain transfer agent, polymerization inhibitor, etc. for controlling the degree of polymerization.

When suspension polymerization is used as a toner production method, a dispersant may be used. Examples of the dispersant used include inorganic compounds and organic compounds.
Inorganic compounds include tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate , Bentonite, silica, alumina and the like.
Examples of the organic compound include polyvinyl alcohol, gelatin, methyl cellulose, methyl hydroxypropyl cellulose, ethyl cellulose, sodium salt of carboxymethyl cellulose, starch and the like.
These dispersants are used by being dispersed in an aqueous phase. A preferable blending amount of these dispersants is 0.2 to 10.0 parts by mass with respect to 100 parts by mass of the polymerizable monomer.

  Commercially available dispersants may be used as they are, but in order to obtain dispersed particles having a fine uniform particle size, the inorganic compound can be produced in a dispersion medium under high-speed stirring. For example, in the case of tricalcium phosphate, a preferable dispersant can be obtained by suspension polymerization by mixing an aqueous sodium phosphate solution and an aqueous calcium chloride solution under high-speed stirring.

  Moreover, in order to refine | miniaturize these dispersing agents, you may use together 0.001-0.1 mass part surfactant with respect to 100 mass parts of polymerizable monomers. As the surfactant, commercially available nonionic, anionic or cationic surfactants can be used. For example, sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, stearin Potassium acid and calcium oleate are preferably used.

When a direct polymerization method is used as a toner production method, the toner can be specifically produced by the following production method.
Add a release agent, colorant, charge control agent, polymerization initiator and other additives consisting of a low softening substance into the monomer, and dissolve or disperse it uniformly with a homogenizer, ultrasonic disperser, etc. Get things. The obtained monomer composition is dispersed in an aqueous phase containing a dispersion stabilizer by a usual stirrer, homomixer, homogenizer or the like. Preferably, the droplets made of the monomer composition are granulated by adjusting the stirring speed and time so as to have a desired toner particle size. Thereafter, stirring may be performed to such an extent that the particle state is maintained and the sedimentation of the particles is prevented by the action of the dispersion stabilizer. The polymerization is carried out at a polymerization temperature of 40 ° C. or higher, generally 50 to 90 ° C. The temperature may be raised in the latter half of the polymerization reaction, and for the purpose of improving the durability, a part of the aqueous medium is retained after the latter half of the reaction or after the completion of the reaction in order to remove unreacted polymerizable monomers and byproducts. You may leave. After completion of the reaction, the produced toner particles are recovered by washing and filtration and dried. In the direct polymerization method, it is usually preferable to use 300 to 3000 parts by weight of water as a dispersion medium with respect to 100 parts by weight of the monomer composition.

Further, in the toner production method, emulsion aggregation obtained through a process of aggregating at least polymer fine particles and colorant fine particles to form a fine particle aggregate and an aging step of causing fusion between the fine particles in the fine particle aggregate In the case of using the method, it is possible to produce toner by the following production method.
The polymer fine particles used in the emulsion aggregation method may be fine particles emulsified and dispersed in an aqueous solvent, such as fine emulsion particles obtained by emulsion polymerization of a known polymerizable monomer, or emulsification in which the above polymer is dissolved. Fine particles are preferably used.
The average particle size of these emulsified fine particles is preferably from 0.05 μm to 3 μm, more preferably from 0.1 μm to 1 μm, and particularly preferably from 0.1 μm to 0.5 μm. The average particle diameter can be measured using a fine particle measuring apparatus (for example, UPA manufactured by Microtrac). If the particle size is smaller than 0.05 μm, it is difficult to control the aggregation rate, which is not preferable. On the other hand, if the particle size is larger than 3 μm, the toner particle size obtained by agglomeration becomes too large, so that it is unsuitable for applications requiring high resolution as a toner.

These emulsified fine particles can be agglomerated by adding an aggregating agent such as an electrolyte to the emulsified dispersion with stirring, if necessary, and further heating to form fine particle aggregates.
The electrolyte used may be either an organic salt or an inorganic salt, but preferably a monovalent or divalent or higher polyvalent metal salt is used. Specific examples of such salts include NaCl, KCl, LiCl, Na ₂ SO ₄ , K ₂ SO ₄ , Li ₂ SO ₄ , MgCl ₂ , CaCl ₂ , MgSO ₄ , CaSO ₄ , ZnSO ₄ , Al ₂ (SO ₄ ) ₃ , Fe ₂ (SO ₄ ) _{3 and the} like.

In adding the electrolyte, the temperature of the mixed dispersion is preferably kept at 40 ° C. or lower. When an electrolyte is added under conditions where the temperature exceeds 40 ° C., rapid aggregation occurs, and particle size control may become difficult, and the bulk density of the obtained particles may be lowered.
Thereafter, the mixture is heated to produce aggregated particles. The aggregated particle formation temperature may be any temperature according to the aggregated form of the particles. Stirring may be performed in a reaction tank having a normal known stirring device such as a paddle blade, squid blade, three retreat blades, Max blend blade, full zone blade, double helical, etc., homogenizer, homomixer, Henschel mixer, etc. Can also be used.

  The particle size growth by the aggregation process is carried out until particles having substantially the same size as the toner particles are obtained, but can be controlled relatively easily by adjusting the pH and temperature of the dispersion. The value of pH varies depending on the type and amount of emulsifier used and the target particle size of the toner, so it cannot be uniquely defined. However, when an anionic surfactant is mainly used, the pH is usually 2 to 6, and the cationic surface activity. When the agent is used, a pH of about 8 to 12 is usually used.

Next, the aging process will be described.
The toner used in the replenishment developer of the present invention can be obtained through a aging step for causing fusion between fine particles in the fine particle aggregate after the step of forming the fine particle aggregate.
In order to increase the stability of the fine particle aggregate obtained in the aggregation step, the fine particle aggregate is held for a predetermined time at a temperature higher than the glass transition temperature (Tg) of the polymer primary particle, thereby fusing the aggregated particles. Wake up. The aging step can be performed using a stirrer similar to the stirrer used in the aggregation step.

  The toner particles obtained through each of the above steps are obtained by solid-liquid separation according to a known method, collecting the toner particles, and then washing and drying the toner particles as necessary.

  These toners may be classified to control the particle size distribution, and as a method therefor, a multi-division classifier using inertial force is preferably used. By using this apparatus, a toner having a preferable particle size distribution in the present invention can be efficiently produced.

The toner used for the replenishment developer of the present invention preferably has a weight average particle diameter (D ₄ ) of 3.0 μm or more and 11.0 μm or less. A more preferred weight average particle size is 4.5 μm or more and 9.0 μm or less. When the weight average particle diameter (D ₄ ) of the toner in the replenishment developer is within this range, an image with good dot reproducibility can be obtained. When the weight average particle diameter (D ₄ ) of the toner is less than 3.0 μm, the specific surface area of the toner increases, the surface existing amount on the carrier in the replenishment developer increases, and the toner is replenished into the developing device. The mixing property with the carrier in the developing device is deteriorated and the uniformity is deteriorated. On the other hand, when the weight average particle diameter (D ₄ ) of the toner exceeds 11.0 μm, the dot reproducibility is deteriorated and high image quality cannot be achieved.
The proportion of particles having a particle size of 0.6 μm or more and 2.0 μm or less is preferably 30% by number or less.
When high-speed printing is performed with a plurality of developing sleeves, the replenished developer may be used immediately. In such a case, the carrier and the toner are not sufficiently agitated in the developing device, and the charge of the toner becomes nonuniform and the image is disturbed.
If a replenishment developer in which a toner containing at least a binder resin and a colorant is blended at a ratio of 2 parts by weight to 50 parts by weight with respect to 1 part by weight of the carrier is used as the replenishment developer, the developer is deteriorated. Not only can this be prevented, but since the carrier and toner are already mixed, non-uniformity in the charging of the toner can be suppressed.
However, if the proportion of particles that are 0.6 μm or more and 2.0 μm or less is large, the coverage of the carrier changes, and the toner in the replenishment developer does not charge well, resulting in image deterioration. End up.

In addition, it is preferable that the average circularity of particles having an equivalent circle diameter (number basis) of 2.0 μm or more of the toner is 0.91 or more and 0.99 or less. When the thing of the said range is used, it is preferable when making transferability and developability compatible. If the average circularity of the toner is lower than 0.91, the transfer efficiency may decrease. In addition, the toner charge distribution is not uniform, which may cause image defects.
Methods for measuring the weight average particle diameter, equivalent circle diameter, and average circularity will be described later.

  The replenishment developer of the present invention preferably contains at least a toner and a carrier, and the carrier is preferably made of a magnetic material or a carrier core containing a resin and a magnetic material and a coating resin that coats the surface of the carrier core.

  The carrier or carrier core used in the replenishment developer of the present invention is not particularly limited as long as the following physical properties are satisfied. For example, it may be a so-called resin-impregnated carrier in which (i) a porous magnetic body (including porous ferrite) is impregnated with a resin, and (ii) a magnetic body-containing resin in which the magnetic body is dispersed in the resin. It may be a carrier core. Preferably (ii) a magnetic substance-containing resin carrier core is a magnetic substance-containing resin carrier core.

(I) The carrier core for the resin-impregnated carrier will be described.
The carrier core for a resin-impregnated carrier is manufactured using a porous magnetic material. Examples of porous magnetic materials include Ca—Mg—Fe ferrite, Li—Fe ferrite, Mn—Mg—Fe ferrite, Ca—Be—Fe ferrite, Mn—Mg—Sr—Fe ferrite, Li -Ferrite magnetic bodies of iron-based oxides such as -Mg-Fe-based ferrite and Li-Rb-Fe-based ferrite are included. Ferrites of iron-based oxides can be obtained by mixing metal oxides, carbonates, nitrates, and the like in a wet or dry manner and calcining to obtain a desired ferrite composition. The obtained iron oxide ferrite is pulverized to submicron. Water for adjusting the particle size is added to the pulverized ferrite in an amount of 20 to 50% by mass with respect to the ferrite, and 0.1 to 10% by mass of, for example, polyvinyl alcohol (molecular weight 500 to 10,000) is added as a binder. A slurry is prepared by adding 0.5 to 15% by mass of a metal carbonate such as calcium carbonate for controlling the density.

  The slurry can be granulated using a spray dryer or the like to obtain a porous magnetic material. Here, the particle size of the porous magnetic material can be controlled by appropriately adjusting the viscosity of the slurry and the size of the nozzle of the spray dryer.

(Ii) The magnetic substance-containing resin carrier core will be described.
As a method for producing the magnetic substance-containing resin carrier core, there is a method obtained by polymerizing monomers constituting the resin in the presence of the magnetic substance.

  At this time, as monomers used for polymerization, in addition to vinyl monomers, bisphenols and epichlorohydrin for forming epoxy resins; phenols and aldehydes for forming phenol resins; urea resins are formed Urea and aldehydes for forming; melamine and aldehydes for forming melamine resin are used.

  Phenol resin is preferable as the resin for forming the magnetic substance-containing resin carrier used in the present invention. As phenols for producing the phenol resin, m-cresol, p-tert-butylphenol, o-, in addition to phenol, are used. Examples thereof include compounds having a phenolic hydroxyl group such as alkylphenols such as propylphenol, resorcinol, and bisphenol A, and halogenated phenols in which a benzene nucleus or alkyl group is partially or entirely substituted with a chlorine atom or a bromine atom. Of these, phenol (hydroxybenzene) is more preferable.

  Examples of aldehydes for producing the phenol resin include formaldehyde and furfural in the form of either formalin or paraaldehyde. Of these, formaldehyde is particularly preferable.

  The molar ratio of aldehydes to phenols is preferably 1 or more and 4 or less, particularly preferably 1.2 or more and 3 or less. When the molar ratio of aldehydes to phenols is less than 1, particles are difficult to generate, and even if they are generated, the resin does not easily cure, so the strength of the generated particles tends to be weak. On the other hand, when the molar ratio of aldehydes to phenols is larger than 4, unreacted aldehydes remaining in the aqueous medium after the reaction tend to increase.

  Examples of the basic catalyst used for polycondensation of phenols and aldehydes include those used in the production of ordinary resol type resins. Examples of such basic catalysts include aqueous ammonia, hexamethylenetetramine, and alkylamines such as dimethylamine, diethyltriamine, and polyethyleneimine. The molar ratio of these basic catalysts to phenols is preferably 0.02 or more and 0.30 or less.

In the magnetic substance-containing resin carrier core, the magnetic substance is preferably magnetite fine particles or magnetic ferrite fine particles containing at least an iron element. Further, in order to adjust the magnetic properties of the carrier, a part of the magnetic material contained in the magnetic material-containing resin carrier may be replaced with a nonmagnetic inorganic compound. It is more preferable that the nonmagnetic inorganic compound is hematite (α-Fe ₂ O ₃ ) fine particles in order to make the dispersibility in the carrier uniform and adjust the magnetic properties and true specific gravity of the carrier. A nonmagnetic inorganic compound has a specific resistance value larger than that of a magnetic substance.

  The number average particle size of the magnetic material is preferably 0.02 μm or more and 2 μm or less from the viewpoint of making the state of the carrier particle surface uniform. The nonmagnetic inorganic compound preferably has a number average particle size of 0.05 μm or more and 5 μm or less, and the magnetic core particle is preferably 1.1 times or more larger than the particle size of the magnetic material. It is preferable for further increasing the surface resistance value.

The amount of the magnetic substance used for the magnetic substance-containing resin carrier core is 70% by mass or more and 95% by mass or less (more preferably 80% by mass or more and 92% by mass or less) with respect to the magnetic substance-containing resin carrier core. However, it is preferable for reducing the true specific gravity of the magnetic carrier and ensuring sufficient mechanical strength.
Further, the magnetic substance is contained in an amount of 30 to 99% by mass with respect to the total amount of the magnetic substance and the nonmagnetic inorganic compound in the magnetic substance-containing resin carrier core. It is preferable to adjust to prevent carrier adhesion and to adjust the specific resistance value of the magnetic substance-containing resin carrier core.

  As a method for producing a magnetic substance-containing resin carrier core using a phenol resin, for example, in an aqueous medium containing phenols, aldehydes, and a magnetic substance, phenols and aldehydes are polymerized in the presence of a basic catalyst. Thus, a magnetic substance-containing resin carrier core can be obtained. When a magnetic substance-containing resin carrier core is manufactured by this method, the average circularity is easily adjusted to the above range, and this method is a preferable manufacturing method.

  As another method for manufacturing the above-mentioned magnetic material-containing resin carrier core, a vinyl-based or non-vinyl-based thermoplastic resin, a magnetic material, and other additives are sufficiently mixed by a mixer, and then heated rolls, kneaders, extensibles. There is a method in which a magnetic material-containing resin carrier core is obtained by melting and kneading using a kneader such as a ruder, cooling this, and then crushing and classifying. At this time, it is preferable to thermally or mechanically spheroidize the obtained magnetic substance-containing resin carrier core and use it as a magnetic substance-containing resin carrier core.

  The carrier core is preferably impregnated with a coating resin or coated on the surface with a coating resin from the viewpoint of imparting charge to the toner and releasing properties. As the coating resin, an insulating resin is preferably used. The insulating resin that can be used in this case may be a thermoplastic resin or a thermosetting resin.

Examples of thermoplastic resins include: polystyrene; acrylic resins such as polymethyl methacrylate and styrene-acrylic acid copolymers; styrene-butadiene copolymers; ethylene-vinyl acetate copolymers; polyvinyl chloride; Polyvinylidene fluoride resin; fluorocarbon resin; perfluorocarbon resin; solvent-soluble perfluorocarbon resin; polyvinyl alcohol; polyvinyl acetal; polyvinylpyrrolidone; petroleum resin; cellulose, cellulose acetate, cellulose nitrate, methylcellulose, hydroxymethylcellulose, hydroxymethylcellulose, hydroxypropylcellulose Such as cellulose derivatives; novolak resin; low molecular weight polyethylene; saturated alkyl polyester resin; polyethylene terephthalate; Terephthalate, polyarylates such aromatic polyester resins; polyamide resins; polyacetal resins; polycarbonate resins; polyether sulfone resins; polysulfone resin; polyphenylene sulfide resins; polyether ketone resins.

  Examples of thermosetting resins include phenolic resins, modified phenolic resins, maleic resins, alkyd resins, epoxy resins, acrylic resins, unsaturated polyesters obtained by polycondensation of maleic anhydride, terephthalic acid and polyhydric alcohols, urea Resin, melamine resin, urea-melamine resin, xylene resin, toluene resin, guanamine resin, melamine-guanamine resin, acetoguanamine resin, gliptal resin, furan resin, silicone resin, polyimide, polyamideimide resin, polyetherimide resin, polyurethane resin Is mentioned.

  The above-mentioned resins can be used alone or in combination. In addition, a curing agent or the like can be mixed with a thermoplastic resin and cured for use. As a particularly preferable form, it is preferable to use a resin having a higher release property for a toner having a small particle diameter and containing a release agent.

  Furthermore, the coat resin may contain particles having conductivity and particles having charge controllability. Such a coating resin is preferably coated on the carrier core by an appropriate method, either alone or by adding conductive particles or charge controllable particles to the monomer forming the resin. These particles are preferably contained from the viewpoint of providing a soft and quick charge to a toner having a small particle size and having a low-temperature fixability.

The particles having conductivity are preferably those having a specific resistance of 1 × 10 ⁸ Ωcm or less, and more preferably those having a specific resistance of 1 × 10 ⁶ Ωcm or less. Specifically, the conductive particles are preferably particles containing at least one kind of particles selected from carbon black, magnetite, graphite, zinc oxide, and tin oxide. In particular, as the particles having conductivity, carbon black having good conductivity is preferable in terms of improving the charge imparting property (rise of charge amount) to the toner.
It is preferable that the conductive particles have a number average particle size of 1 μm or less in order to prevent the particles from falling off from the carrier and to function as a uniform conductive site.

  The particles having charge controllability include organometallic complex particles, organometallic salt particles, chelate compound particles, monoazo metal complex particles, acetylacetone metal complex particles, hydroxycarboxylic acid metal complex particles, and polycarboxylic acid. Examples include metal complex particles and polyol metal complex particles. A charge control agent dispersed in the toner particles may be used, but use of resin particles having a functional group or inorganic particles treated with a treatment agent having a functional group improves the charge imparting property to the toner. It is preferable for this purpose.

  Specific examples of the particles having charge controllability include polymethyl methacrylate resin particles, polystyrene resin particles, melamine resin particles, phenol resin particles, nylon resin particles, silica particles, titanium oxide particles, And particles containing at least one kind of particles selected from alumina particles. Further, in the case of inorganic particles, it is preferable to use them after being treated with various coupling agents in order to develop charge controllability and conductivity.

  The above particles having charge controllability preferably have a number average particle diameter of 0.01 μm or more and 1.50 μm or less in order to function as a uniform charging site.

The coating amount of the coating resin on the carrier core is 0.1 parts by mass or more and 5.0 parts by mass or less with respect to 100 parts by mass of the carrier core. It is preferable for enhancing the properties. The blending amount of the conductive particles and the charge controllable particles is preferably 0.1 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the coating resin.
If the conductive particles or the charge controllable particles are added in an amount exceeding 30 parts by mass, the particles are difficult to disperse in the coating resin, and the particles may be detached from the magnetic carrier. In particular, when carbon black is added, the toner may be contaminated with carbon black or the member may be contaminated as the durability increases.

The carrier used for the replenishment developer of the present invention has a 50% particle size (D ₅₀ ) based on volume distribution of 15 μm or more and 70 μm or less. Preferably, they are 20 micrometers or more and 70 micrometers or less, More preferably, they are 25 micrometers or more and 60 micrometers or less. When the 50% particle size (D ₅₀ ) based on the volume distribution of the magnetic carrier is within this range, an image with good dot reproducibility can be obtained over a long period without fogging. When the 50% particle size (D ₅₀ ) based on the volume distribution of the carrier is less than 15 μm, the fluidity of the carrier is lowered, and fine powder is likely to accumulate, so that uniform carrier recovery may not be performed satisfactorily. If the thickness exceeds 70 μm, the carrier particle size is large, so that the density of the magnetic brush becomes coarse, and as a result, the image may be deteriorated. The particle size of the carrier can be within the above range by classification with an air classifier (Elbow Jet Lab EJ-L3, manufactured by Nippon Steel Mining Co., Ltd.) or the like.
A method for measuring the 50% particle size (D ₅₀ ) based on the volume distribution will be described later.

When a plurality of developing sleeves are used and high-speed printing is performed, the replenished developer is used immediately. In such a case, the carrier and the toner are not sufficiently agitated in the developing device, and the charge of the toner becomes non-uniform and the image is disturbed.
If a replenishment developer in which a toner containing at least a binder resin and a colorant is blended at a ratio of 2 parts by weight to 50 parts by weight with respect to 1 part by weight of the carrier is used as the replenishment developer, the developer is deteriorated. Not only can this be prevented, but since the carrier and toner are already mixed, non-uniformity in the charging of the toner can be suppressed.
In order to more effectively suppress toner non-uniformity, it is desirable to reduce the distribution of the particle size of the carrier so that the coverage of the toner on the carrier is uniform. That is, by using a carrier having a weight average particle diameter (D ₄ ) / number average particle diameter (D ₁ ) of 1.3 or less, the toner can be effectively charged during replenishment development, and high-speed printing can be performed. It becomes a replenishment developer that achieves high image quality even at times.
Method of measuring the weight average particle diameter (D ₄₎ and the number average particle diameter (D ₁₎ will be described later.

If the true specific gravity of the carrier is 4.2 g / cm ³ or less, the difference in specific gravity between the carrier and the toner is small, so that the excess carrier is pumped up to the developer recovery port and becomes excessive in the developing device. Can effectively discharge the carrier. For this reason, it is possible to obtain an image with good dot reproducibility without suppressing carrier deterioration and without fogging.
However, if the true specific gravity of the carrier exceeds 4.2 g / cm ³ , the specific gravity difference between the toner and the carrier increases, and in particular, the coarse powder carrier is difficult to be pumped up to the developer collection port, and the carrier is not easily collected stably. . As a result, the recovered carrier has a lot of fine carrier powder, and the carrier particle size becomes coarse. For this reason, when it is used for a long time, the resolution is lowered and it is difficult to maintain high image quality. In order to avoid this phenomenon, the apparatus tends to be complicated by strengthening the stirring mechanism.
Further, when the true specific gravity of the carrier is less than 2.5 g / cm ³ , the carrier is likely to be developed on the photosensitive drum during development, and the carrier may be adhered.
For this reason, development is performed while supplying the replenishment developer to the developing device, and the excess carrier in the developing device is effectively discharged from the developing device as necessary to maintain high image quality over a long period of time and In order to suppress carrier adhesion on the drum, the true specific gravity of the carrier needs to be 2.5 g / cm ³ or more and 4.2 g / cm ³ or less. Preferably, 2.7 g / cm
³ or more 4.1 g / cm ³ or less, still more preferably not more than 3.0 g / cm ³ or more 4.0 g / cm ^3.
A method for measuring the true specific gravity will be described later.

The magnetization strength of the carrier is 40 Am ² / kg or more and 70 Am ² / kg or less under a magnetic field of 1000 / 4π (kA / m). When the carrier is within this range, an image with good dot reproducibility can be obtained over a long period of time. When the intensity of magnetization of the carrier is less than 40 kAm ² / kg, it is easy to be developed on the photosensitive drum at the time of development, and carrier adhesion may occur. Further, since the magnetization is small, the delivery of the agent from the first developing sleeve 8 to the second developing sleeve 11 is not successful, and the amount of the developer that is accompanied increases. As a result, the charge of the toner becomes uneven and the image may be deteriorated. When the magnetization intensity of the carrier exceeds 70 kAm ² / kg, the stress on the developer between the regulating blade 9 and the first developing sleeve 8 increases, and the carrier may be deteriorated.
A method for measuring the magnetization intensity will be described later.

  The carrier contained in the replenishment developer of the present invention preferably contains 90% by number or more of particles having an average circularity of 0.85 or more and 0.95 or less and a circularity of 0.80 or more. The average circularity is preferably 0.87 or more and 0.93 or less, and more preferably 0.88 or more and 0.92 or less. The average circularity is a coefficient representing the shape of the roundness of the particle, and is obtained from the maximum diameter of the particle and the measured particle projected area. An average circularity of 1.00 indicates a perfect sphere (perfect circle), and a smaller numerical value indicates an elongated or irregular shape.

When the carrier included in the replenishment developer of the present invention has an average circularity of 0.85 or more and 0.95 or less, the carrier has sufficient carrier strength, excellent charge imparting property to the toner, and damage to the toner. The toner spent is not easily generated, and the durability is excellent. When the average circularity is less than 0.85, it means that the particles have an irregular shape. In this case, the charge imparting property to the toner may be deteriorated, which is not preferable. On the other hand, when the average circularity exceeds 0.95, the specific surface area of the carrier becomes small, and the charge imparting property to the toner may be lowered.
A method for measuring the average circularity of the carrier will be described later.

  When the toner and the carrier are mixed and used as a two-component developer in the developing device, the mixing ratio of the toner and the carrier is 0.02 parts by mass or more and 0.35 parts by mass with respect to 1 part by mass of the carrier. It is preferably used in the range of not more than 0.04 parts by weight, more preferably not less than 0.04 parts by weight and not more than 0.25 parts by weight, particularly preferably not less than 0.05 parts by weight and not more than 0.20 parts by weight. If it is less than 0.02 parts by mass, the image density tends to be low, and if it exceeds 0.35 parts by mass, fog and in-machine scattering are likely to occur.

  The replenishment developer of the present invention contains the toner in a blending ratio of 2 parts by weight or more and 50 parts by weight or less with respect to 1 part by weight of the carrier. When the toner content is less than 2 parts by mass with respect to 1 part by mass of the carrier, it is necessary to replenish a large amount of replenishment developer particularly when an image having a high printing density is printed at a high speed. As a result, the developer for replenishment and the developer in the development period are used for development before being sufficiently mixed, and the toner becomes non-uniformly charged. As a result, the image may deteriorate. In addition, if the toner is contained in an amount of more than 50 parts by mass with respect to 1 part by mass of the magnetic carrier, the deteriorated carrier is used for a long time without being discharged, and when the developing device having a plurality of sleeves is used, the carrier is deteriorated. In particular, it may progress and the image may deteriorate.

A preferred ratio of the specific gravity of the two-component developer in the developing device to the specific gravity of the replenishing developer (specific gravity of the two-component developer in the developing device / specific gravity of the replenishing developer) is 1.5 or more 3.0 or less.
When high-speed printing is performed with a plurality of developing sleeves, the supplied replenishment developer may be used immediately. For this reason, in order to obtain uniform toner chargeability and high image quality, the replenishment developer replenished in the developing device and the two-component developer in the developing device can quickly become uniform by stirring. is necessary. Here, when the ratio of the specific gravity of the supplied two-component developer in the developing device is larger than 3.0, the supplied developer and the two-component system in the developing device are caused by the difference in specific gravity. The developer is not very uniform. For this reason, the chargeability of the toner becomes non-uniform and the image quality deteriorates.
In order to reduce the specific gravity ratio of the replenishment developer to less than 1.5, two methods are conceivable: reducing the specific gravity of the carrier or lowering the carrier ratio in the replenishment developer. If the specific gravity of the carrier is reduced, it is likely to be developed on the photosensitive drum at the time of development, and carrier adhesion may occur and the image quality may deteriorate. If the carrier ratio in the replenishment developer is lowered, the deteriorated carrier may be used for a long time without being discharged, and the image quality may deteriorate.

  There are two types of electrophotographic process development systems that output full-color images: a rotary development system having at least one photosensitive drum and a plurality of development devices, and a tandem development system having a plurality of photosensitive drums and a plurality of development devices. In either case, the replenishment developer of the present invention can be used.

Here, the tandem development method will be described in detail.
FIG. 2 shows the positional relationship between the image carrier (photosensitive drum) 10 and the developing device 1 at each of the Y, M, C, and K stations in the tandem developing system. The Y, M, C, and K stations have substantially the same configuration, and form yellow (Y), magenta (M), cyan (C), and black (K) images in a full-color image, respectively. In the following description, for example, with the developing device 1, the developing device 1Y, the developing device 1M, the developing device 1C, and the developing device 1K in each of the Y, M, C, and K stations are commonly referred to.

First, the operation of the entire image forming apparatus will be described with reference to FIG.
The photosensitive drum 10 is provided so as to be rotatable. The photosensitive drum 10 is uniformly charged by a primary charger 21, and light modulated in accordance with an information signal by a light emitting element 22 such as a laser. To form a latent image. The latent image is visualized as a toner image by the developing device 1 in the following process. The toner image is transferred by the first transfer charger 23 onto the transfer paper 27 that is a recording material conveyed by the transfer material conveyance sheet 24 for each station, and then fixed by the fixing device 25 to form a permanent image. obtain. Further, the transfer residual toner on the photosensitive drum 10 is removed by the cleaning device 26. Further, the toner in the developer consumed in the image formation is supplemented by supplying a supply developer containing at least the toner and the carrier from the supply tank 20. In this embodiment, a method of directly transferring the photosensitive drums 10M, 10C, 10Y, and 10K to the transfer paper 27 that is a recording material conveyed to the transfer material conveyance sheet 24 is used. An image having a structure in which a transfer body is provided, and a toner image of each color is primarily transferred from the photosensitive drums 10M, 10C, 10Y, and 10K of each color to an intermediate transfer body, and then a composite toner image of each color is secondarily transferred onto a transfer sheet. The present invention can also be applied to a forming apparatus.

  Next, the developing device will be described in detail with reference to examples. Of course, two developer carriers in the rotation direction of the image carrier (photosensitive drum), and a developer for forming a developer layer on the developer carrier Using a developing device having at least a layer thickness regulating member, development is performed while supplying a replenishment developer containing at least toner and carrier to the developing device, and excess carrier inside the developing device is removed from the developing device as necessary. Any developing device having a discharge mechanism may be used.

For example, there are the following developing devices.
FIG. 1 shows the positional relationship between the image carrier (photosensitive drum) 10 and the developing device 1 at each of the Y, M, C, and K stations in the full-color image forming apparatus as shown in FIG. . The Y, M, C, and K stations have substantially the same configuration, and form yellow (Y), magenta (M), cyan (C), and black (K) images in a full-color image, respectively. This will be described with reference to FIG.

The developing device 100 includes a first developing sleeve (first developer carrying member) 8 and a second developing sleeve (second developer carrying member) in a developing container 2 containing a two-component developer containing toner and a magnetic carrier. ) 11 and a regulating blade 9 which is a developer regulating member that regulates the layer thickness of the developer carried on the surface of the first developing sleeve 8.
By having a plurality of developing sleeves in this way, high image quality can be achieved in high-speed printing at a rotational speed of 250 mm / sec or more, particularly 500 mm / sec or more, which is difficult to achieve with one developing sleeve. Can do.

  Further, the developing container 2 has an opening at a position corresponding to the developing region facing the photosensitive drum 10, and the first developing sleeve 8 can be rotated so that the first developing sleeve 8 is partially exposed to the photosensitive drum 10 side. It is arranged. The first developing sleeve 8 is made of a non-magnetic material, and a first magnet roller 8 ′ as a first magnetic field generating means is installed in a non-rotating state inside the first developing sleeve 8. The magnet roller 8 is developed. It has a pole S2, and magnetic poles S1, N1, N2, and N3 that convey the developer. The second developing sleeve is disposed in the opening of the developing container 2 in parallel with the first developing sleeve.

In the above developing apparatus, when the replenishment developer of the present invention is used, the closest distance between the regulating blade 9 and the first developing sleeve 8 is preferably 100 μm or more and 3000 μm or less. Furthermore, it is preferable that the closest distance is 200 μm or more and 2000 μm or less. By setting the closest distance within the above range, high image quality can be achieved even during high-speed printing.
This is because when the closest distance is within this range, an appropriate amount of developer is accumulated on the back (upstream side) of the regulating blade 9, and the developer is uniformly carried on the sleeve.
When the closest distance is shorter than 100 μm, the gap through which the developer passes is narrow, and therefore, when the printing is performed at a high speed, the developer is subjected to strong stress, and the developer is significantly deteriorated. On the other hand, if the closest distance is longer than 3000 μm, the developer hardly accumulates on the back side (upstream side) of the regulating blade 9, and as a result, the developer is not uniformly carried on the first developing sleeve 8 and the image deteriorates. There is.

Further, the product of the strength of the carrier magnetization in the replenishment developer under the magnetic field of 1000 / 4π (kA / m) and the magnetic flux density of the magnetic pole S1 closest to the regulating blade 9 is 3000 mT · Am ^2. / Kg or more and 11200 mT · Am ² / kg or less is preferable, and 5000 mT · Am ² / kg or more and 10000 mT · Am ² / kg or less is more preferable. Since the strength of magnetization of the carrier used in the present invention under a magnetic field of 1000 / 4π (kA / m) is 40 Am ² / kg or more and 70 Am ² / kg or less, the product of the magnetization and the magnetic flux density of the sleeve is 11200 mT · If it is larger than Am ² / kg, that is, if the magnetic flux density of the magnetic pole S1 is large, a lot of developer is attracted to the magnetic pole S1. As a result, the amount of developer that accumulates on the back (upstream side) of the regulating blade 9 increases, where a large number of developers are mixed together, and the stress on the developer increases. In particular, during high-speed printing, the sleeve rotates at high speed, so that the deterioration of the developer proceeds rapidly, and as a result, the image deteriorates. On the other hand, if it is less than 3000 mT · Am ² / kg, the density of the magnetic brush on the sleeve is lowered and the image is lowered. Furthermore, the magnetic force with which the developer is carried on the sleeve becomes weak, and the carrier may adhere to the photosensitive drum during development, resulting in image defects.

A substantially central portion in the developing container 2 is divided into a developing chamber 3 and an agitating chamber 4 by a partition wall 7 extending in a direction perpendicular to the paper surface, and the developer is accommodated in the developing chamber 3 and the agitating chamber 4. More desirable.
This is because by dividing the developing chamber 3 and the stirring chamber 4 in this way, the developer is sufficiently stirred and the mixed developer can be supplied to the first developing sleeve 8 even during high-speed printing.
In the developing chamber 3 and the agitating chamber 4, first and second conveying screws 5 and 6, which are circulation means for agitating and conveying the developer T and circulating in the developing container 2, are arranged, respectively. The first conveying screw 5 is disposed substantially parallel to the bottom of the developing chamber 3 along the axial direction of the developing sleeve 8, and rotates to allow the developer T in the developing chamber 3 to move in one direction along the axial direction. Transport. The second conveying screw 6 is disposed at the bottom of the stirring chamber 4 substantially in parallel with the first conveying screw 5 and conveys the developer T in the stirring chamber 4 in the opposite direction to the first conveying screw 5. . In this way, the developer T is transported between the developing chamber 3 and the agitating chamber 4 through the openings (communication portions) at both ends of the partition wall 7 by transport by the rotation of the first and second transport screws 5 and 6. Circulated.

  Further, the replenishment developer is replenished from a replenishment developer introduction port (not shown) installed in the stirring chamber 4, and the excess carrier in the developing device is installed in the development chamber 3 as necessary. It is desirable to discharge from a certain waste outlet (not shown).

  A different polarity is disposed at a position closest to the first developing sleeve 8 and the second developing sleeve 11, for example, magnetic poles N3 and S3 are disposed as shown in FIG. To the second developing sleeve. It is more desirable that the developing device using the replenishment developer of the present invention has this configuration. This is because the developer used for the development is surely sent to the agitating chamber 4 and agitated, and the agitated developer in the developing chamber 3 can be used for the development. In this way, developers having the same chargeability can always be used, so that the same image can be produced over a long period of time.

  Further, the closest distance between the first developing sleeve and the second developing sleeve is preferably 15 μm or more and 3000 μm or less, and more preferably 100 μm or more and 2000 μm or less. If the closest distance is shorter than 15 μm, the developer that has been delivered to the second developing sleeve from the first developing sleeve cannot pass and passes through the gap smaller than the carrier particle size. Compressed. As a result, the toner and the external additive contained in the toner may adhere to the carrier and the chargeability may deteriorate. Further, if the closest distance is longer than 3000 μm, the developer is not delivered successfully because the distance is long, and as a result, the developer that is not delivered and goes to the first developing sleeve increases. The developed developer has been developed once, so the toner to carrier ratio is different from that of other developers. For this reason, the chargeability of the toner becomes non-uniform and image unevenness may occur.

  A suitable method for measuring physical properties related to the present invention will be described below.

<Measurement of toner particle size distribution and weight average particle size (D ₄ )>
As a measuring device, Coulter Counter TA-II or Coulter Multisizer II (manufactured by Coulter Inc.) is used. As the electrolytic solution, an about 1% NaCl aqueous solution is used. As the electrolytic solution, an electrolytic solution prepared using primary sodium chloride or, for example, ISOTON (registered trademark) -II (manufactured by Coulter Scientific Japan) can be used.

As a measurement method, 0.1 to 5 ml of a surfactant (preferably alkylbenzenesulfone hydrochloride) is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution, and 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample is suspended is dispersed for about 1 to 3 minutes with an ultrasonic disperser, and the volume and number of the sample are measured for each channel by the measuring apparatus using a 100 μm aperture as the aperture. Volume distribution and number distribution are calculated. From these obtained distributions, the weight average particle diameter (D ₄ ) of the sample is determined. As channels, 2.00 to 2.52 μm; 2.52 to 3.17 μm; 3.17 to 4.00 μm; 4.00 to 5.04 μm; 5.04 to 6.35 μm; 6.35 to 8. 00 μm; 8.00 to 10.08 μm; 10.08 to 12.70 μm; 12.70 to 16.00 μm; 16.00 to 20.20 μm; 20.20 to 25.40 μm; 25.40 to 32.00 μm; 13 channels of 32.00-40.30 μm are used.

<Measurement of average circularity of toner>
The equivalent circle diameter and circularity of the toner are used as a simple method for quantitatively expressing the shape of the toner particles. In the present invention, the flow type particle image measuring device “FPIA-2100 type” (manufactured by Sysmex Corporation) is used. ) Is used for calculation, and the following equations (1) to (2) are used for calculation.

  Here, the “particle projected area” is the area of the binarized toner particle image, and the “peripheral length of the particle projected image” is the length of the contour line obtained by connecting the edge points of the toner particle image. Define. The measurement uses the perimeter of the particle image when image processing is performed at an image processing resolution of 512 × 512 (pixels of 0.3 μm × 0.3 μm).

In the present invention, the circularity is an index indicating the degree of unevenness of the toner particles, and is 1.000 when the toner particles are completely spherical. The more complicated the surface shape, the smaller the circularity.
The average circularity C, which means the average value of the circularity frequency distribution, is calculated from the following equation, where ci is the circularity (center value) at the dividing point i of the particle size distribution and m is the number of measured particles.

  In addition, “FPIA-2100”, which is a measuring apparatus used in the present invention, calculates the circularity of each particle, and then calculates the average circularity. 1.0 is divided into classes equally divided every 0.01, and the average circularity is calculated using the center value of the division points and the number of measured particles.

As a specific measuring method, 10 ml of ion-exchanged water from which impure solids have been removed in advance is prepared in a container, and a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant therein, followed by further measurement. Add 0.02 g of sample and disperse uniformly. As a means for dispersion, an ultrasonic disperser “Tetora 150 type” (manufactured by Nikka Ki Bios Co., Ltd.) is used, and dispersion treatment is performed for 2 minutes to obtain a dispersion for measurement. In that case, it cools suitably so that the temperature of this dispersion may not be 40 degreeC or more. In addition, in order to suppress variations in circularity, the flow type particle image analyzer F
The installation environment of the device is controlled to 23 ° C. ± 0.5 ° C. so that the in-machine temperature of PIA-2100 is 26 to 27 ° C., and automatic focusing is performed using 2 μm latex particles at regular intervals, preferably every 2 hours. I do.

  To measure the shape of the toner particles, the flow type particle image measuring device is used, and the concentration of the dispersion is readjusted so that the color toner particle concentration at the time of measurement is 3000 to 10,000 particles / μl. Measure more than one. After the measurement, this data is used to cut data less than 2 μm, and the average circularity of the toner particles is obtained.

  Furthermore, “FPIA-2100”, which is a measuring apparatus used in the present invention, improves the magnification of the processed particle image as compared with “FPIA-1000” conventionally used for calculating the shape of the toner. Furthermore, the accuracy of toner shape measurement is improved by improving the processing resolution of the captured image (256 × 256 → 512 × 512), thereby achieving more reliable capture of fine particles. Therefore, when it is necessary to measure the shape more accurately as in the present invention, the FPIA 2100 that can obtain information on the shape more accurately is more useful.

<50% particle diameter on a volume basis of the carrier _{(D 50)} and average circularity>
The 50% particle size (D ₅₀ ) and average circularity based on the volume distribution of the carrier are measured as follows using, for example, a multi-image analyzer (manufactured by Beckman Coulter).

A solution obtained by mixing about 1% NaCl aqueous solution and glycerin at 50% by volume: 50% by volume is used as the electrolytic solution. Here, the NaCl aqueous solution may be prepared using primary sodium chloride, and may be, for example, ISOTON (registered trademark) -II (manufactured by Coulter Scientific Japan). Glycerin may be a special grade or first grade reagent.
To the electrolytic solution (about 30 ml), 0.1 to 1.0 ml of a surfactant (preferably alkylbenzenesulfone hydrochloride) is added as a dispersant, and 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample is suspended is dispersed for about 1 minute with an ultrasonic disperser to obtain a dispersion.

Using a 200 μm aperture and a 20 × lens as the aperture, the equivalent circle diameter and circularity are calculated under the following measurement conditions.
Average luminance within measurement frame: 220 to 230,
Measurement frame setting: 300,
SH (threshold): 50,
Binarization level: 180

The electrolytic solution and the dispersion liquid are put into a glass measuring container, and the concentration of carrier particles in the measuring container is set to 5 to 10% by volume. Stir the contents of the glass measuring container at the maximum stirring speed. The sample suction pressure is 10 kPa. When the carrier specific gravity is large and the sedimentation is likely to occur, the measurement time is 15 to 30 minutes. Further, the measurement is interrupted every 5 to 10 minutes to replenish the sample solution and the electrolytic solution-glycerin mixed solution.
The number of measurements is 2000. After the measurement is finished, the main body software removes a defocused image, aggregated particles (multiple simultaneous measurements), etc. on the particle image screen.
The circularity and equivalent circle diameter of the carrier are calculated by the following formula.

Here, “Area” is the projected area of the binarized carrier particle image, and “MaxLength” is defined as the maximum diameter of the carrier particle image. The equivalent circle diameter is represented by the diameter of a perfect circle when “Area” is the area of the perfect circle. The equivalent circle diameter is divided into 4 to 100 μm in 256, and is used by logarithmically displaying on a volume basis. Using this, the 50% particle size (D ₅₀ ) based on volume distribution is obtained. The average circularity is obtained by adding the circularity of each particle and dividing by the total number of particles. FIG. 1 shows an example of a graph of measurement results. The “arithmetic average value” in the “circularity arithmetic statistical value” section in the figure indicates the average circularity.

<True specific gravity of carrier>
The true specific gravity of the carrier particles contained in the developer for replenishment of the present invention can be measured using a dry automatic densimeter autopycnometer (manufactured by Yuasa Ionics). In this measuring machine, measurement is performed using a gas phase substitution method. The measurement principle is based on Archimedes' principle, and gas is used as a replacement medium. Specifically, a shut-off valve is provided between an empty sample chamber having the same volume and a comparison chamber. After pressurizing the sample chamber to 1 atm, the shut-off valve is opened to release gas to the comparison chamber. The pressure drops to 1/2 atmosphere. When the sample chamber volume is halved with the sample, the pressure obtained by the same operation is 1/3 atm.
Since the relationship between pressure and volume follows the gas equation of state PV = nRT (nRT: constant value), the volume V of the sample can be calculated from the measurement of the pressure P.

<Strength of magnetization of carrier>
The magnetization strength of the carrier contained in the replenishment developer of the present invention can be obtained by a vibrating magnetic field type magnetic property device VSM (Vibrating sample magnetometer), a direct current magnetization property recording device (BH tracer), or the like. . Preferably, it can measure with an oscillating magnetic field type magnetic property apparatus. Examples of the oscillating magnetic field type magnetic property apparatus include an oscillating magnetic field type magnetic property automatic recording apparatus BHV-30 manufactured by Riken Denshi Co., Ltd. Using this, it can be measured by the following procedure. A cylindrical plastic container is packed sufficiently densely, while an external magnetic field of 1000 / 4π (kA / m) (1000 oersted) is created, and the magnetization moment of the carrier filled in the container is measured in this state. . Further, the actual mass of the carrier filled in the container is measured to determine the magnetization strength (Am ² / kg) of the carrier.

<Specific gravity ratio of developer and replenishment developer>
The specific gravity ratio between the developer of the present invention and the replenishment developer can be determined as follows.
Using a dry automatic densimeter AccuPick 1330 (Shimadzu Corporation), the specific gravity (A) of the developer and the specific gravity (B) of the replenishment developer are obtained. In this measuring instrument, the density is measured by a dry method by a constant volume expansion method.
The specific gravity ratio between the developer of the present invention and the replenishment developer is calculated and calculated as follows.

<Measurement of molecular weight by GPC>
The molecular weight of the chromatogram by gel permeation chromatograph (GPC) is measured under the following conditions.
Resin prepared by stabilizing the column in a heat chamber at 40 ° C., and flowing tetrahydrofuran (THF) as a solvent at a flow rate of 1 ml / min to the column at this temperature to adjust the sample concentration to 0.05 to 0.6% by mass. Measurement is performed by injecting 50 to 200 μl of a THF sample solution. An RI (refractive index) detector is used as the detector. As the column, in order to accurately measure a molecular weight region of 1 × 10 ³ to 2 × 10 ⁶ , it is preferable to combine a plurality of commercially available polystyrene gel columns. For example, μ-styragel 500, 103, 104 manufactured by Waters , 105, and combinations of shodex KA-801, 802, 803, 804, 805, 806, and 807 manufactured by Showa Denko KK are preferable.

In measuring the molecular weight of a sample, the molecular weight distribution of the sample is calculated from the relationship between the logarithmic value of a calibration curve prepared from several types of monodisperse polystyrene standard samples and the number of counts. As a standard polystyrene sample for preparing a calibration curve, for example, Pressure Chemical
Co. Manufactured by Toyo Soda Kogyo Co., Ltd., molecular weight of 6 × 10 ² , 2.1 × 10 ³ , 4 × 10 ³ , 1.75 × 10 ⁴ , 5.1 × 10 ⁴ , 1.1 × 10 ⁵ It is appropriate to use 3.9 × 10 ⁵ , 8.6 × 10 ⁵ , 2 × 10 ⁶ , 4.48 × 10 ⁶ , and use at least about 10 standard polystyrene samples.

<Measurement of number average particle diameter (D ₁ ) and weight average particle diameter (D ₄ ) of carrier>
The number average particle diameter (D ₁ ) and the weight average particle diameter (D ₄ ) of the carrier particles contained in the replenishment developer of the present invention are those having a measurement range of submicron to several hundred microns. It can be measured using a dry or wet laser diffraction particle size distribution meter. Examples of the laser diffraction particle size distribution analyzer include laser diffraction particle size distribution analyzers SALD-3000, SALD-2200, and SALD-300V (manufactured by Shimadzu Corporation).

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

[Carrier Production Example 1]
4. A magnetite powder having a number average particle size of 0.30 μm and a magnetization strength of 72 Am ² / kg under a magnetic field of 1000 / 4π (kA / m) and a hematite powder having a number average particle size of 0.30 μm, respectively. 0% by mass of a silane coupling agent (3- (2-aminoethylaminopropyl) trimethoxysilane) was added, and the mixture was stirred and mixed at 110 ° C. or higher in a container to treat each fine particle.
・ Phenol 10 parts by mass ・ Formaldehyde solution 6 parts by mass (formaldehyde 40%, methanol 10%, water 50%)
-Treated magnetite 75 parts by mass-Treated hematite 9 parts by mass The above material, 5 parts by mass of 28% ammonia water, and 25 parts by mass of water are placed in a flask, and the temperature is raised and maintained up to 85 ° C over 40 minutes while stirring and mixing. The resulting phenol resin was cured by a polymerization reaction for 3 hours. Thereafter, the cured phenol resin was cooled to 30 ° C., water was further added, the supernatant was removed, the precipitate was washed with water, and then air-dried. Next, this is dried under reduced pressure (5 mmHg or less) at a temperature of 60 ° C., and a magnetic material-containing resin carrier core (hereinafter referred to as “magnetic material dispersion” in which spherical magnetic materials in which the magnetic materials are dispersed is dispersed. Also referred to as “resin core”.
As a coating resin, a copolymer of methyl methacrylate and perfluorooctyl acrylate (copolymerization ratio (mass% ratio) 8: 2, weight average molecular weight 40,000) is used, and this is 100 mass of the magnetic material dispersed resin core at the time of coating. A carrier coat solution containing 10% by mass of a copolymer of methyl methacrylate and perfluorooctyl acrylate was prepared using a mixed solvent of methyl ethyl ketone and toluene as a solvent so as to be 1 part by mass with respect to parts. In addition, 1.0 part by mass of melamine resin (number average particle diameter 0.2 μm) and 1.0 part by mass of carbon black (number average particle diameter 30 nm, DBP oil absorption 50 ml / 100 g) may be added to the carrier coat solution using a homogenizer. Mix. Next, the magnetic material-dispersed resin core is added to the mixed solution, and the solvent is volatilized at 70 ° C. while continuously applying a shear stress to the mixed solution. And a copolymer.
The resin-coated magnetic material-dispersed resin core coated with a copolymer of methyl methacrylate and perfluorooctyl acrylate is heat-treated by stirring at 100 ° C. for 2 hours, cooled, crushed, and classified with a 200 mesh sieve. Carrier 1 was obtained. As shown in Table 1, the carrier 1 has a volume distribution standard 50% particle size (D ₅₀ ) of 35 μm, D ₄ / D ₁ = 1.22, a true specific gravity of 3.5 g / cm ³ , and a magnetization strength of 52 Am ^2. / Kg, average circularity was 0.92.

[Carrier Production Example 2]
Carrier 2 was obtained in the same manner as Carrier Production Example 1 except that the number average particle size of magnetite powder was changed from 0.30 μm to 0.40 μm and the number average particle size of hematite powder was changed from 0.30 μm to 0.40 μm. . As shown in Table 1, carrier 2 has a 50% particle diameter (D ₅₀ ) of 50 μm based on volume distribution, D ₄ / D ₁ = 1.20, true specific gravity of 3.7 g / cm ³ , and magnetization strength of 52 Am ^2. / Kg, average circularity was 0.87.

[Carrier Production Example 3]
In Carrier Production Example 2, Carrier 3 was obtained in the same manner as Carrier Production Example 2, except that the treated magnetite was changed from 75 parts by mass to 80 parts by mass and the treated hematite was changed from 9 parts by mass to 2 parts by mass. As shown in Table 1, the carrier 3 has a 50% particle size (D ₅₀ ) of 50 μm based on volume distribution, D ₄ / D ₁ = 1.16, true specific gravity of 4.0 g / cm ³ , and magnetization strength of 60 Am ^2. / Kg, average circularity was 0.93.

[Carrier Production Example 4]
In Carrier Production Example 3, 0.45 [mu] m and the number average particle diameter of the magnetite powder from 0.40 .mu.m, the magnetization intensity 80 Am ² / kg from 72Am ² / kg, and 25 parts by mass from 10 parts by weight of phenol, formaldehyde solution A carrier 4 was obtained in the same manner as in Carrier Production Example 3 except that the amount was changed from 6 parts by mass to 15 parts by mass. As shown in Table 1, the carrier 4 has a 50% particle size (D ₅₀ ) of 62 μm based on volume distribution, D ₄ / D ₁ = 1.24, a true specific gravity of 2.7 g / cm ³ , and a magnetization strength of 68 Am ^2. / Kg, average circularity was 0.94.

[Carrier Production Example 5]
Ferrite component Fe ₂ O ₃ : 56.3 mol%
MgO: 23.0 mol%
SrO: 20.7 mol%
The ferrite raw material oxide blended in the above composition was wet-mixed with a ball mill, dried and ground, then fired at 750 ° C. for 2 hours, and ground with a crusher to about 0.1 to 1.0 mm. Further, the mixture was wet pulverized by a ball mill to form a slurry, added with 1.0% polyvinyl alcohol as a binder and 3% CaCO ₃ as a pore adjuster, granulated into spherical particles by a spray dryer method, and an oxygen gas concentration of 0.5 The mixture was calcined at 950 ° C. in a nitrogen gas atmosphere of% and sieved with a sieve having an opening of 250 μm to remove coarse particles. Subsequently, classification was performed with an air classifier (Elbow Jet Lab EJ-L3, manufactured by Nippon Steel Mining Co., Ltd.) to obtain a carrier core which is a porous magnetic material.
Next, toluene and methyl ethyl ketone (4: 1) mixed solvent 1000 parts by mass Styrene / methyl methacrylate copolymer (4: 6, M _w = 50,000) 70 parts by mass Methyl methacrylate / perfluoropropylethyl methacrylate copolymer
(80:20, M _w = 18,000) 30 parts by mass The above components were mixed to prepare a coating liquid. Next, the composition of the solution is adjusted so that the solid content of the coating resin is 5.0% by mass with respect to the carrier core which is the porous magnetic material, and the solvent is removed by drying under reduced pressure while stirring and mixing with a vacuum kneader. The carrier 5 was obtained by baking at 140 ° C. for 2 hours and sieving with a sieve having an opening of 74 μm. The obtained carrier is a resin-impregnated carrier in which a porous magnetic material is impregnated with a resin. As shown in Table 1, the carrier 5 has a 50% particle size (D ₅₀ ) of 25 μm based on volume distribution, D ₄ / D ₁ = 1.28, a true specific gravity of 4.1 g / cm ³ , and a magnetization strength of 42 Am ^2. / Kg, average circularity was 0.85.

[Carrier Production Example 6]
In the manufacture example of the carrier 5, CaCO ₃ is changed from 3% to 15%, and the carrier 6 is changed in the same manner as the carrier manufacture example 5 except that the classification condition, specifically, the set value of the suction air volume is changed. Obtained. As shown in Table 1, the carrier 6 has a 50% particle size (D ₅₀ ) of 80 μm based on volume distribution, D ₄ / D ₁ = 1.28, true specific gravity 2.4 g / cm ³ , and magnetization strength 38 Am ^2. / Kg, average circularity was 0.82.

[Carrier Production Example 7]
These metal oxide particles were weighed so that the molar ratio was Fe ₂ O ₃ = 89.8 mol% and MgO = 10.2 mol%, and mixed using a ball mill. After calcining the obtained mixed powder, it is pulverized by a ball mill, further granulated by a spray dryer, sintered, and further classified to form a carrier core (hereinafter referred to as “magnetic particles”) that is a porous magnetic material. Also referred to as).
Furthermore, the surface of the magnetic particles obtained above was coated with a thermosetting silicone resin by the following method. Carrier coat containing 10% by mass of silicone resin using toluene as a solvent so that the coating amount of the silicone resin on the surface of the magnetic particles is 2.0 parts by mass with respect to 100 parts by mass of the coated resin-coated magnetic particles A solution was made.
The magnetic particles were added to the carrier coating solution, and the silicone resin was coated on the surface of the magnetic particles by volatilizing the solvent at 70 ° C. while continuously applying shear stress thereto.
The resin-coated magnetic particles coated with the silicone resin are heat-treated by stirring at 200 ° C. for 3 hours, then cooled and crushed, and screened with a 200-mesh sieve to remove coarse particles, and then an air classifier ( Classification was carried out with Elbow Jet Lab EJ-L3 (manufactured by Nippon Steel Mining Co., Ltd.), and the particle size was adjusted to obtain Carrier 7.
As shown in Table 1, the carrier 7 has a volume distribution based 50% particle size (D ₅₀ ) of 50 μm, D ₄ / D ₁ = 1.34, a true specific gravity of 5.0 g / cm ³ , and a magnetization strength of 50 Am ^2. / Kg, average circularity was 0.83.

[Carrier Production Example 8]
In Carrier Production Example 7, carrier production except that the ratio of metal oxide particles was changed to Fe ₂ O ₃ = 58.6 mol%, Li ₂ O = 35.8 mol%, and CaO = 5.6 mol%. Example 7
In the same manner, Carrier 8 was obtained. As shown in Table 1, the carrier 8 has a 50% particle size (D ₅₀ ) of 50 μm based on volume distribution, D ₄ / D ₁ = 1.38, a true specific gravity of 4.3 g / cm ³ , and a magnetization strength of 75 Am ^2. / Kg, average circularity was 0.80.

[Carrier Production Example 9]
A carrier 9 was obtained in the same manner as in the carrier production example 8 except that the pulverization conditions and classification conditions in the carrier production example 8 were changed. As shown in Table 1, the carrier 9 has a volume distribution standard 50% particle size (D ₅₀ ) of 13 μm, D ₄ / D ₁ = 1.32, a true specific gravity of 4.3 g / cm ³ , and a magnetization strength of 75 Am ^2. / Kg, average circularity was 0.85.

[Binder resin production example]
As the material of the vinyl polymer unit, 2.0 mol of styrene, 0.21 mol of 2-ethylhexyl acrylate, 0.14 mol of fumaric acid, 0.03 mol of α-methylstyrene dimer, dicumylpar as a crosslinking agent and a polymerization initiator 0.05 mol of oxide was put into the dropping funnel. As a material of the polyester unit, 7.0 mol of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) ) 3.0 mol of propane, 3.0 mol of terephthalic acid, 1.9 mol of trimellitic anhydride, 5.0 mol of fumaric acid and 0.2 g of dibutyltin oxide were put into a 4-liter four-necked flask made of glass. A thermometer, a stirring rod, a condenser, and a nitrogen introducing tube were attached to the four-necked flask, and the four-necked flask was placed in a mantle heater. Next, after the inside of the four-necked flask was replaced with nitrogen gas, the temperature was gradually increased while stirring, and the monomer and polymerization of the vinyl polymer unit were performed from the previous dropping funnel while stirring at a temperature of 145 ° C. The initiator was added dropwise over 4 hours. Next, the obtained product was heated to 200 ° C. and reacted for 4 hours to obtain a hybrid resin. As for the molecular weight of this hybrid resin by GPC, the weight average molecular weight (M _w ) was 81500, the number average molecular weight (Mn) was 3100, and the peak molecular weight was 15500.

[Toner Production Example 1]
-100 parts by mass of the above binder resin-5 parts by mass of purified Fischer-Tropsch wax-1 part by mass of 3,5-di-t-butylsalicylic acid aluminum compound-C.I. I. Pigment Blue 15: 3 8 parts by mass After the above materials were thoroughly mixed with a Henschel mixer (FM-75 type, manufactured by Mitsui Miike Chemical Co., Ltd.), a twin-screw kneader (PCM-30 type, Ikegai set at a temperature of 130 ° C.) Kneading was carried out by an ironworker. The obtained kneaded material was cooled and coarsely pulverized to 1 mm or less with a hammer mill to obtain a coarsely pulverized material. The obtained coarsely crushed material was finely pulverized using a collision type airflow pulverizer using a high-pressure gas (IDS-5 manufactured by Nippon Pneumatic Industry Co., Ltd.). The obtained finely pulverized product had a weight average particle diameter (D ₄ ) of 4.9 μm and an average circularity of 0.915.
Next, the obtained finely pulverized product is put into the surface reforming apparatus at a rate of 1.3 kg per time using the surface modifying apparatus shown in FIG. However, the surface treatment was performed for 70 seconds at a rotation speed of the dispersion rotor 32 of 5800 rpm (rotational peripheral speed 130 m / sec). The valve 41 was opened and taken out as a processed product).
At this time, in this embodiment, ten square disks 33 are installed on the upper part of the dispersion rotor 32, the distance between the guide ring 36 and the square disk 33 on the dispersion rotor 32 is 30 mm, and the dispersion rotor 32 and the liner 34 are arranged. Was set at 5 mm. The blower air volume was 14 m ³ / min, the temperature of the refrigerant passed through the jacket and the cold air temperature T1 were −20 ° C.
As a result of repeated operation for 20 minutes in this state, the temperature T2 behind the classification rotor 35 was stabilized at 27 ° C. The toner particles obtained after the surface treatment had a weight average particle diameter (D ₄ ) of 5.4 μm, an average circularity of 0.940, and a classification yield of 82%.
Furthermore, using a mesh surface fixed wind sieve high voltor (NR-300 type, manufactured by Shin Tokyo Machine Co., Ltd .: air brush attached to the back of the wire mesh), this has a diameter of 30 cm, an opening of 29 μm, and an average diameter of the wire Was provided with a 30 μm wire mesh, and the toner powder was supplied to the wire mesh with an air flow of 5 Nm ³ / min to obtain toner particles from which coarse particles were separated. The obtained toner particles had a particle diameter of 12.7 μm or more and less than 0.1% by volume. Further, the separated coarse particles were about 0.2% by mass of the toner particles that passed through the sieve.
To 100 parts by mass of the obtained toner particles, 1.0 part by mass of titanium oxide having an average particle diameter of 40 nm and hydrophobized and 0.5 part by mass of amorphous silica having an average particle diameter of 110 nm were added as inorganic fine particles. Addition and mixing were performed to obtain toner 1. As shown in Table 2, the obtained toner 1 has a weight average particle diameter (D ₄ ) of 7.0 μm, a ratio of particles of 0.6 μm to 2.0 μm, 10% by number, and an average circularity of 0.8. 930.

[Toner Production Example 2]
In Toner Production Example 1, C.I. I. Toner 2 was obtained in the same manner as in Toner Production Example 1 except that Pigment Yellow 93 was used instead of Pigment Blue 15. As shown in Table 2, the obtained toner 2 has a weight average particle diameter (D ₄ ) of 5.5 μm, a ratio of particles of 0.6 μm or more and 2.0 μm or less of 26% by number, and an average circularity of 0.8. 935.

[Toner Production Example 3]
In Toner Production Example 1, C.I. I. Toner 3 was obtained in the same manner as in Toner Production Example 1 except that it was changed to quinacridone instead of Pigment Blue 15. As shown in Table 2, the obtained toner 3 has a weight average particle diameter (D ₄ ) of 6.0 μm, a ratio of particles of 0.6 μm to 2.0 μm, 16% by number, and an average circularity of 0.8. 932.

[Toner Production Example 4]
In Toner Production Example 1, C.I. I. Instead of Pigment Blue 15, Toner 4 was obtained in the same manner as in Toner Production Example 1 except that carbon black was changed to 5 parts by mass. As shown in Table 2, the obtained toner 4 has a weight average particle diameter (D ₄ ) of 5.8 μm, a ratio of particles of 0.6 μm to 2.0 μm in 18% by number, and an average circularity of 0.8. 940.

[Toner Production Example 5]
・ 100 parts by mass of polyester resin (condensation polymer of propoxylated bisphenol A, fumaric acid and trimellitic acid)
・ C. I. Pigment Blue 15: 3 7 parts by mass, 3,5-di-t-butylsalicylic acid aluminum compound 1 part by mass, low molecular weight polyolefin (mp. 124 ° C.) 5 parts by mass Henschel mixer (FM-75 type, Mitsui Miike) The mixture was mixed by Kako Koki Co., Ltd., and melt kneaded by a twin-screw kneader (PCM-30 type, manufactured by Ikekai Tekko Co., Ltd.) while sucking the vent port connected to a suction pump. This melt-kneaded product was roughly crushed with a hammer mill to obtain a 1 mm mesh pass crushed product. Furthermore, after finely pulverizing with a jet mill, it was classified with an air classifier (Elbow Jet Lab EJ-L3, manufactured by Nippon Steel Mining Co., Ltd.) to obtain toner particles.
0.8 parts by mass of hydrophobized titanium oxide fine powder (hexamethyldisilazane 5% treated) (number average particle diameter of primary particles: 0.05 μm), 100 parts by mass of the toner particles, hydrophobized oxidized Silica fine powder (hexamethyldisilazane 10% treated) (number average particle size of primary particles: 0.03 μm) is mixed by 0.8 part by mass Henschel mixer (FM-75 type, manufactured by Mitsui Miike Chemical Co., Ltd.) As a result, Toner 5 was obtained. As shown in Table 2, the obtained toner 5 has a weight average particle diameter (D ₄ ) of 6.6 μm, a ratio of particles of 0.6 μm or more and 2.0 μm or less of 14% by number, and an average circularity of 0.8. 936.

[Toner Production Example 6]
450 parts by mass of 0.1M Na ₃ PO ₄ aqueous solution was added to 710 parts by mass of ion-exchanged water, heated to 60 ° C., and then at 12000 rpm using a TK homomixer (manufactured by Special Machine Industries). Stir. To this, 68 parts by mass of 1.0 M CaCl ₂ aqueous solution was gradually added to obtain an aqueous medium containing Ca ₃ (PO ₄ ) ₂ .
on the other hand,
-Styrene 100 mass parts-N-butyl acrylate 20 mass parts-C.I. I. Pigment Blue 15: 3 (coloring agent) 8 parts by mass, 3,5-di-t-butylsalicylic acid aluminum compound 1 part by mass, saturated polyester (polar resin, Mp = 8000) 7 parts by mass, ester wax (melting point 70 ° C.) 14 parts by mass The above material was heated to 60 ° C., and uniformly dissolved and dispersed at 10,000 rpm using a TK homomixer (manufactured by Tokushu Kika Kogyo). In this, 7 parts by mass of a polymerization initiator 2,2′-azobis (2,4-dimethylvaleronitrile) was dissolved to prepare a polymerizable monomer composition.
The polymerizable monomer composition was put into an aqueous medium and stirred at 10,000 rpm for 10 minutes with a TK homomixer at 60 ° C. in an N ₂ atmosphere to granulate the polymerizable monomer composition. Then, while stirring with a paddle stirring blade, the temperature was raised to 80 ° C. and reacted for 10 hours. After the completion of the polymerization reaction, the residual monomer was distilled off under reduced pressure. After cooling, hydrochloric acid was added to dissolve Ca ₃ (PO ₄ ) _{2 and the} like, followed by filtration, washing with water and drying to obtain toner particles.
Hydrophobicized silica fine powder (hexamethyldisilazane 10% treated) (number average particle size of primary particles: 0.03 μm) 0.5 parts by mass with respect to 100 parts by mass of the obtained toner particles Toner 6 was obtained by externally adding 0.5 parts by mass of titania powder (treated with 5% hexamethyldisilazane) (number average particle diameter of primary particles: 0.03 μm). As shown in Table 2, the obtained toner 6 has a weight average particle diameter (D ₄ ) of 6.5 μm, a ratio of particles of 0.6 μm or more and 2.0 μm or less of 11% by number, and an average circularity of 0.8. 940.

[Toner Production Example 7]
Dispersion A
Styrene 350 parts by mass n-butyl acrylate 100 parts by mass Acrylic acid 25 parts by mass t-dodecyl mercaptan 10 parts by mass or more were mixed and dissolved to prepare monomer mixture A.
100 parts by mass of paraffin wax dispersion having a melting point of 78 ° C. (solid content concentration 30%, dispersed particle size 0.14 μm)
Anionic surfactant 1.2 parts by mass (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen SC)
・ 0.5 parts by weight of nonionic surfactant (manufactured by Sanyo Chemical Co., Ltd .: Nonipol 400)
-Ion exchange water 1530 mass parts The said composition is disperse | distributed in a flask and a heating is started, performing nitrogen substitution. When the liquid temperature reached 70 ° C., a solution prepared by dissolving 6.56 parts by mass of potassium persulfate with 350 parts by mass of ion-exchanged water was added thereto. While maintaining the liquid temperature at 70 ° C., the monomer mixture A was charged and stirred, and the liquid temperature was raised to 80 ° C. and emulsion polymerization was continued for 5 hours. After that, the liquid temperature was adjusted to 40 ° C. and filtered through a filter. A was obtained. Thus, the particle diameter in the obtained dispersion liquid is 0.17 μm in average particle diameter, 60 ° C. in glass transition point of solid content, 14,000 in weight average molecular weight (M _w ), and 11 in peak molecular weight. 000. Paraffin wax was contained in the polymer in an amount of 6% by mass. As a result of observing a thin piece of this solid content with a transmission electron microscope, it was confirmed that the polymer particles encapsulated the wax particles.

Dispersion B
A ratio of 350 parts by mass of styrene, 100 parts by mass of n-butyl acrylate, and 30 parts by mass of acrylic acid was mixed and dissolved to prepare a monomer mixture B.
100 parts by mass of a Fischer-Tropsch wax dispersion with a melting point of 105 ° C. (solid content concentration 30%, dispersion particle size 0.15 μm)
・ Anionic surfactant 1.5 parts by mass (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen SC)
・ 0.5 parts by weight of nonionic surfactant (manufactured by Sanyo Chemical Co., Ltd .: Nonipol 400)
-Ion exchange water 1530 mass parts The said composition is disperse | distributed in a flask and a heating is started, performing nitrogen substitution. When the liquid temperature reached 65 ° C., a solution prepared by dissolving 5.85 parts by mass of potassium persulfate with 300 parts of ion-exchanged water was added thereto. While maintaining the liquid temperature at 65 ° C., the monomer mixture B was charged and stirred, and the liquid temperature was raised to 75 ° C. and emulsion polymerization was continued for 8 hours. The liquid temperature was adjusted to 40 ° C. and filtered through a filter. B was obtained. Thus, the particle diameter in the obtained dispersion was 0.16 μm in average particle diameter, 63 ° C. in glass transition point of solid content, and 650,000 in weight average molecular weight (M _w ). The hydrocarbon wax was contained in the polymer in an amount of 6% by mass, and as a result of observing a thin piece of the solid content with a transmission electron microscope, it was confirmed that the wax particles were encapsulated.

Dispersion C
・ C. I. Pigment Blue 15: 3 12 parts by mass / Anionic surfactant 2 parts by mass (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen SC)
-Ion exchange water 78 mass parts or more was mixed, and it disperse | distributed using the sand grinder mill, and obtained the colorant dispersion liquid C.

300 parts by mass of the dispersion A, 150 parts by mass of the dispersion B, and 25 parts by mass of the dispersion C were put into a 1-liter separable flask equipped with a stirrer, a cooling tube, and a thermometer and stirred. As a flocculant, 180 parts by mass of a 10% sodium chloride aqueous solution was dropped into this mixed solution, and the flask was heated to 54 ° C. while stirring the inside of the flask. After maintaining at 48 ° C. for 1 hour, it was confirmed by observation with an optical microscope that associated particles having a diameter of about 5 μm were formed.

  In the subsequent fusion process, after adding 3 parts by mass of an anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen SC), the stainless steel flask was sealed and stirring was continued using a magnetic seal. While heating to 100 ° C., it was held for 3 hours. Then, after cooling, the reaction product was filtered, sufficiently washed with ion exchange water, and then dried to obtain toner particles 7.

For 100 parts of the toner particles, 0.7 part of hydrophobic silica (hexamethyldisilazane 10% treatment) having a BET specific surface area of 200 m ² / g and hydrophobic titanium oxide (hexamethyldisilane) having a primary particle diameter of 80 nm. Toner 7 was obtained by adding 0.7 parts of silazane 5% treatment) and dry mixing. As shown in Table 2, the obtained toner 7 has a weight average particle diameter (D ₄ ) of 6.8 μm, a ratio of particles of 0.6 μm to 2.0 μm, 8% by number, and an average circularity of 0.8. 945.

[Toner Production Example 8]
10.0 mol of ethylene glycol, 3.5 mol of terephthalic acid, 6.5 mol of 1,10-decanedicarboxylic acid and 0.2 g of dibutyltin oxide were put in a 4-liter four-necked flask made of glass. A thermometer, a stirring rod, a condenser, and a nitrogen introducing tube were attached to the four-necked flask, and the four-necked flask was placed in a mantle heater. Next, after the inside of the four-necked flask was replaced with nitrogen gas, the temperature was gradually raised to 200 ° C. while stirring and reacted for 4 hours to obtain a polyester resin. As for the molecular weight of this polyester resin by GPC, the peak molecular weight was 15500, and the weight average molecular weight (M _w ) was 81500.

  100 parts by weight of the obtained polyester resin and 20 parts by weight of a paraffin wax dispersion having a melting point of 98 ° C. used in Toner Production Example 1 were placed in 860 parts by weight of ion-exchanged water and stirred at 90 ° C. with a sand grinder mill. A polyester resin dispersion A was prepared.

  450 parts by mass of this polyester resin dispersion A and 25 parts of dispersion C used in Toner Production Example 7 were charged into a 1-liter separable flask equipped with a stirrer, a cooling tube and a thermometer and stirred. To this mixed solution, 180 parts of a 10% aqueous sodium chloride solution was added dropwise as a flocculant, and the mixture was heated to 54 ° C. while stirring the inside of the flask in a heating oil bath. After maintaining at 48 ° C. for 1 hour, it was confirmed by observation with an optical microscope that associated particles having a diameter of about 5 μm were formed.

  In the subsequent fusion process, after adding 3 parts by mass of an anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen SC), the stainless steel flask was sealed and stirring was continued using a magnetic seal. While heating to 100 ° C., it was held for 3 hours. Then, after cooling, the reaction product was filtered, thoroughly washed with ion exchange water, and then dried to obtain toner particles 8.

To 100 parts of the toner particles, 0.7 part of hydrophobic silica (hexamethyldisilazane 10% treatment) having a BET specific surface area of 200 m ² / g and hydrophobic titanium oxide (hexamethyldisiloxane) having a primary particle diameter of 70 nm are used. Toner 8 was obtained by adding 0.7 parts of 5% silazane and dry mixing. As shown in Table 2, the obtained toner 8 has a weight average particle diameter (D ₄ ) of 6.8 μm, a ratio of particles of 0.6 μm to 2.0 μm in 8% by number, and an average circularity of 0. 965.

  The magnetic carrier and toner produced as described above were mixed in a combination and ratio as shown in Table 3 using a tumbler mixer to prepare a developer / replenishment developer. Table 3 shows the ratio of the true specific gravity between the developer and the replenishment developer.

Next, the developing device of a commercially available color copier CLC-5100 (Canon Inc.) was modified as shown in FIG.
The closest distance between the first developing sleeve 8 and the second developing sleeve 11 is 800 μm, the closest distance between the first developing sleeve 8 and the regulating blade 9 is 400 μm, and the magnetic flux density of the S1 pole of the first magnet roller 8 ′ is 100 mT. Remodeled as follows. Further, when the developer toner deviates from the range of 2 parts by mass to 50 parts by mass with respect to 1 part by mass of the carrier, a replenishment developer introduction port (not shown) installed in the stirring chamber 4 Thus, a replenishment developer was introduced, and the excess carrier was modified so that it could be discarded from a waste outlet (not shown) installed in the developing chamber 3. Further, the surface layer of the fixing roller of the fixing unit was changed to a silicone tube, and the oil application mechanism was removed. The developing device was charged with 500 g of developer, and replenished developer was replenished as needed with printing.

Various evaluations were made after 100,000 sheets were printed under the following conditions using this modified machine.
Printing environment: 23 ° C./60% (hereinafter “N / N”), 35 ° C./90% (hereinafter “H / H”)
Paper: Color laser copier paper (81.4 g / m ² ) (Canon Sales Co., Ltd.)
Image forming speed: 400mm / sec
Development sleeve rotation speed: 500 mm / sec
Image: Solid image with an image area of 20%

  The evaluation methods and standards are shown below.

(1) Fog The average reflectance Dr (%) of the paper before image printing was measured with a reflectometer (“REFLECTOMETER MODEL TC-6DS” manufactured by Tokyo Denshoku Co., Ltd.).
Next, a solid white image was printed, and the reflectance Ds (%) of the solid white image was measured. The fog (%) is calculated from the following formula.

A: Less than 0.4% B: 0.4% or more and less than 1.0% C: 1.0% or more

(2) Solid uniformity A solid image having an image area of 50% was printed.
Using a Macbeth Densitometer RD918 type (Macbeth Densitometer RD918manufactured by Mcbeth Co.) equipped with an SPI filter, the maximum density difference was determined by measuring the four corners and the center of the image.
A: 0.00 or more and less than 0.05 B: 0.05 or more and less than 0.20 C: 0.20 or more

(3) Developer transportability (i) Developer rotation Next, the developing device is taken out and disassembled, and the first developing sleeve 8 is not transferred from the first developing sleeve 8 to the second developing sleeve 11. Observed how much agent was taken around.
A: There is no rotation of the developer.
B: There is a slight rotation of the developer.
C: The developer is accompanied.

(Ii) Agent retention on the back of the blade In addition, it was observed how much developer was accumulated on the back of the regulating blade 9.
A: The amount of accumulated developer is small.
B: There is accumulated developer.
C: A large amount of developer has accumulated.

  Table 4 shows the results of these evaluations.

  In Examples 1 to 6 and 8, both fog and solid uniformity after printing 100,000 sheets were good. In addition, there is no agent that goes around the first developing sleeve 8, and there is little agent that accumulates behind the regulating blade. For this reason, it is expected that the stress applied to the developer is small. From the above, when the replenishment developer as in Examples 1 to 6 and 8 is used, it is expected that a good image is maintained even if more printing is performed.

  In Example 7, the fog / solid uniformity after printing 100,000 sheets was somewhat bad although it was at a level where there was no problem in practical use. This is because the ratio of the specific gravity between the developer and the replenishment developer (developer / replenishment developer) is greater than 3.0, so the developer in the developing device and the newly replenished replenishment developer are well stirred. As a result, it is presumed that the charging of the toner became non-uniform as a result.

In Example 9, the fog / solid uniformity after printing 100,000 sheets was a little bad although it was at a level where there was no problem in practical use. This is because the 50% particle diameter (D ₅₀ ) based on the volume distribution of the carrier is a little as large as 62 μm, and as a result, the ears on the sleeve are slightly sparse, and as a result, the image is rough although it is at a level that does not cause any problems in actual use It is guessed that this is because it has become. Further, since the magnetization intensity of the carrier under a magnetic field of 1000 / 4π (kA / m) is a little as high as 68 Am ² / kg, there is a developer that has accumulated on the back of the regulating blade. It is presumed that stress was applied and the developer deteriorated slightly, and as a result, the image was lowered.

  In Comparative Example 1, fog and solid uniformity after printing 100,000 sheets are poor. This is presumably because the carrier developer deteriorated because the replenishment developer did not contain a magnetic carrier, and as a result, the toner was non-uniformly charged.

In Comparative Example 2, fog and solid uniformity after printing 100,000 sheets are poor. This is because the specific gravity of the carrier in the developer for replenishment is larger than 4.2 g / cm ³ , so that the stress applied to the carrier when the developer is agitated in the developing machine is large and the deterioration of the carrier proceeds. This is presumed to be due to uneven charging of the toner. Further, since the specific gravity ratio between the developer and the replenishment developer is large, mixing of the replenishment developer replenished with the developer in the developing device when printing at high speed is insufficient, and as a result, the toner This is thought to be due to the non-uniform charging of the image and the deterioration of the image.

Comparative Example 3 has poor fog and solid uniformity in an H / H environment after printing 100,000 sheets. This is presumably because the 50% particle diameter (D ₅₀ ) based on the volume distribution is larger than 70 μm, so that the ears on the sleeve become rough, and as a result, the image becomes rough. Further, since the strength of magnetization of the carrier in the replenishment developer under a magnetic field of 1000 / 4π (kA / m) is less than 40 Am ² / kg, the first developing sleeve 8 to the second developing sleeve 11 The delivery of the developer is not successful, and the amount of the agent that is accompanied by the first developing sleeve 8 is increasing. For this reason, it is presumed that a developer that has not been stirred well is used for development, which is also a cause of image deterioration.

In Comparative Example 4, fog and solid uniformity in a H / H environment after printing 100,000 sheets is poor. This is because the specific gravity of the carrier in the developer for replenishment is larger than 4.3 g / cm ^{3 and} the strength of magnetization under a magnetic field of 1000 / 4π (kA / m) is larger than 70 Am ² / kg. It is presumed that the carrier is subjected to a load between the control blade and the regulating blade, which causes deterioration of the carrier, and as a result, the toner is non-uniformly charged.

  In Comparative Example 5, fog and solid uniformity after printing 100,000 sheets were deteriorated. This is presumably because the carrier was developed together with the toner because the particle size of the carrier was small and the particle size difference from the toner was small.

As described above, using a developing device having at least two developer carriers in the rotation direction of the image carrier and a developer layer thickness regulating member for forming a developer layer on the developer carrier, A two-component developing method for developing a replenishment developer containing at least toner and carrier while replenishing the developing device, and discharging the excess carrier inside the developing device from the developing device as necessary. A replenishment developer, wherein the replenishment developer contains 2 parts by weight or more and 50 parts by weight or less of a toner containing at least a binder resin and a colorant with respect to 1 part by weight of the carrier, The carrier has a 50% particle size (D ₅₀ ) based on volume distribution of 15 μm or more and 70 μm or less, the true specific gravity of the carrier is 2.5 g / cm ³ or more and 4.2 g / cm ³ or less, and 1000 / 4π ( kA / m) By using a developer for replenishment characterized in that the strength of magnetization of the carrier in a magnetic field of 40 Am ² / kg or more and 70 Am ² / kg or less, or a developing method using the developer, High image quality and high durability can be achieved even during high-speed printing.

It is a schematic diagram which shows an example of the image development apparatus of this invention. It is a schematic diagram showing an example of an image forming apparatus using the replenishment developer of the present invention. 6 is a schematic diagram of a surface modification device used in Toner Production Example 1. FIG. Example of circularity measurement result

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Developing apparatus 2 Developing container 3 Developing chamber 4 Agitation chamber 5 1st conveyance screw (circulation means)
6 Second conveying screw (circulation means)
7 Partition 8 First developing sleeve (first developer carrier)
8 '1st magnet roller 9 Regulating blade (Developer layer thickness regulating member)
10 Photosensitive drum (image carrier)
11 Second developing sleeve (second developer carrier)
11 'second magnet roller 20 replenishing tank 21 primary charger 22 light emitting element 23 first transfer charger 24 transfer material transport sheet 25 fixing device 26 cleaning device 27 transfer paper (recording material)
30 Main body casing 31 Cooling jacket 32 Dispersion rotor 33 Square disk 34 Liner 35 Classification rotor 36 Guide ring 37 Material input port 38 Material supply valve 39 Material supply port 40 Product discharge port 41 Product discharge valve 42 Product extraction port 43 Top plate 44 Fine powder Discharge unit 45 Fine powder discharge port 46 Cold air introduction port 47 First space 48 Second space 49 Surface modification zone 50 Classification zone 100 Developing device

Claims (8)

And two of the developer carrying member in the rotation direction of the image carrier, and a developer layer thickness regulating member for forming a developer layer on the developer carrying member, a developer for replenishment containing at least a toner and a carrier the a least a developing device, a developing device having a means for developing with replenished to the developing device the replenishment developer is discharged from the developing device when necessary excess since the carrier inside the developing device There,
The replenishment developer contains a toner containing at least a binder resin and a colorant at a blending ratio of 2 parts by weight or more and 50 parts by weight or less with respect to 1 part by weight of the carrier,
The carrier has a 50% particle size (D ₅₀ ) based on volume distribution of 15 μm or more and 70 μm or less, the true specific gravity of the carrier is 2.5 g / cm ³ or more and 4.2 g / cm ³ or less, and 1000 / 4π ( A developing device, wherein the intensity of magnetization of the carrier under a magnetic field of kA / m) is 40 Am ² / kg or more and 70 Am ² / kg or less.   2. The development according to claim 1, wherein the carrier comprises a carrier core and a coating resin that coats the surface of the carrier core, and the carrier core contains a magnetic substance, or a resin and a magnetic substance. apparatus.   The developing device according to claim 2, wherein the carrier core is a magnetic material-containing resin carrier core in which a magnetic material is dispersed.   The developing device according to claim 1, wherein the carrier is a resin-impregnated carrier in which a porous magnetic material is impregnated with a coating resin. The product of the magnetization of the carrier and the magnetic flux density of the magnetic pole of the developer carrier closest to the developer layer thickness regulating member under a magnetic field of 1000 / 4π (kA / m) is 3000 mT · Am ² / kg or more and 11200 mT. The developing device according to claim 1, wherein the developing device is Am ² / kg or less.   2. The ratio of the specific gravity of the two-component developer in the developing device to the specific gravity of the replenishing developer (specific gravity of the two-component developer in the developing device / specific gravity of the replenishing developer) is 1.5 or more. The developing device according to claim 1, wherein the developing device is in a range of 0 or less. The closest distance between two of the developer carrying member is not less 15μm or more 3000μm or less, and, between two of the developer carrying member, any claim 1-6, characterized in that the delivery of the developer is performed The developing device according to claim 1. Of the two developer carriers, the developer carrier on the upstream side of the delivery of the developer has a developer layer thickness regulating member, and between the developer layer thickness regulating member and the upstream developer carrier. an apparatus according to any one of claim 1 to 7, the closest distance is equal to or is 100μm or more 3000μm following.

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