JP2008242114A - Spinning method toner for two-component developer, two-component developer and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spinning method toner for a two-component developer, the toner capable of reducing changes in the image density with time upon forming images or reducing toner scattering, to provide a two-component developer containing the above spinning method toner for a two-component developer, and to provide an image forming apparatus using the two-component developer. <P>SOLUTION: The spinning method toner for a two-component developer is to be used in an image forming apparatus that employs a system of forming an electrostatic latent image on the surface of a photoreceptor, forming a magnetic brush of the two-component developer on the surface of a magnetic roll, transferring only the toner from the magnetic brush to the surface of a developing roller disposed opposing to the photoreceptor to form a toner layer, and scattering the toner from the toner layer to develop the electrostatic latent image on the photoreceptor surface into a toner image. The toner is characterized in that the absolute average of the charge distribution q/d is from 0.45 fC/μm to 0.6 fC/μm and that the standard deviation of the charge distribution q/d is not more than 0.24. The two-component developer comprises the above spinning method toner for a two-component developer, and a carrier. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a two-component developer comprising a toner and a carrier, used in an image forming apparatus such as an electrophotographic copying machine or a printer, a spinning toner for the two-component developer, and an image formation using the two-component developer. Relates to the device.

Developers used in image forming apparatuses such as electrophotographic copying machines and printers include a one-component developer containing only toner and a two-component developer composed of toner and a carrier.
The toner used in these applications satisfies the characteristics required in each process such as development, transfer, fixing, and photoreceptor cleaning. Therefore, not only the constituent materials but also the dispersed state of each constituent material and the material state of the toner particle surface. Etc. It is designed from many aspects.
Currently, a pulverization method is known as a toner production method. In the pulverization method, toner materials are usually produced by melt-kneading toner materials such as a binder resin, wax, colorant, charge control agent, etc., cooling the toner materials in a molten state, and pulverizing them. In recent years, there has also been proposed a spinning method in which a toner material in a molten state is drawn into a fiber and pulverized or cut to produce a toner (see, for example, Patent Document 1).

On the other hand, conventionally, as a developing method of an image forming apparatus, a one-component developing method and a two-component developing method are known. In addition, a touch-down development method that combines the excellent characteristics of these development methods (high image quality of the one-component development method and high durability of the two-component development method) has also been proposed.
In the touch-down development method, a magnetic brush is formed on the surface of the magnetic roll with a two-component developer, and only the toner is transferred from the magnetic brush to the surface of the developing roll disposed facing the photoconductor to form a toner layer. In this method, the toner is scattered from the toner layer, and the electrostatic latent image on the surface of the photoreceptor is developed as a toner image.
Japanese Patent Application No. 2006-106235

However, in the touch-down development method, there is a problem that image density fluctuation (selective development) and toner scattering are likely to occur over time when continuous image formation is performed.
These problems can potentially occur in both the one-component development system and the two-component development system, but are particularly likely to occur in the touch-down development system.
For example, the toner manufactured by the pulverization method (pulverization method toner) has a surface state closely related to the dispersion of each component in the toner raw material to be pulverized. For example, when the dispersion diameter of the wax is large, Grinding occurs in the wax part, and the wax is exposed on the surface of the obtained particles. The exposed wax contaminates the member with which the toner comes into contact, causing various problems. In particular, in the case of a two-component developer, contamination of the carrier surface causes toner charging failure, which causes toner scattering, fogging, and the like. In addition, since the pulverized toner has a wide particle size distribution of the obtained particles, a toner having a large particle size is used for development at the time of development, and a toner having a small particle size and low developability tends to remain. This is presumed to cause fluctuations in image density.
On the other hand, toner produced by the spinning method (spinning method toner) has a significantly smaller fracture surface area and a narrower particle size distribution than the pulverized toner due to its production method. Therefore, it is considered that the above problems are less likely to occur compared to the pulverized toner.
However, according to the study of the present inventor, it is difficult to reduce image density fluctuation and toner scattering even when a conventional spinning toner is used as a toner of a two-component developer used in an image forming apparatus of a touch-down development method. It is.
The present invention has been made in view of the above circumstances, and is a two-component developer spinning method toner that can reduce image density fluctuation and toner scattering over time during image formation, and the two-component developer spinning method toner. It is an object of the present invention to provide a two-component developer containing a toner and an image forming apparatus using the two-component developer.

As a result of intensive studies, the present inventor has found that the above problems can be solved by a spinning toner having a predetermined charge amount distribution, and has completed the present invention.
That is, in the first aspect of the present invention, an electrostatic latent image is formed on the surface of the photoreceptor, a magnetic brush is formed on the surface of the magnetic roll with a two-component developer, and only the toner is obtained from the magnetic brush. An image forming apparatus of a type that develops an electrostatic latent image on the surface of the photoreceptor as a toner image by forming a toner layer by transferring it to the surface of a developing roll disposed facing the photoreceptor and flying the toner from the toner layer Spinning toner for two-component developer used in
The absolute value of the charge amount distribution q / d is 0.45 fC / μm or more and 0.6 fC / μm or less, and the standard deviation of the charge amount distribution q / d is 0.24 or less. This is a developer spinning toner.
The second aspect of the present invention is a two-component developer comprising the spinning toner for a two-component developer of the first aspect and a carrier.
According to a third aspect of the present invention, an electrostatic latent image is formed on the surface of the photoconductor, a magnetic brush is formed on the surface of the magnetic roll with a two-component developer, and only the toner is transferred from the magnetic brush to the photoconductor. This is an image forming apparatus of a type in which a toner layer is formed by being transferred to the surface of a developing roll disposed facing the toner, and the toner is scattered from the toner layer to develop the electrostatic latent image on the surface of the photoreceptor as a toner image. And
In the image forming apparatus, the two-component developer according to the second aspect is used as the two-component developer.

  According to the present invention, a two-component developer spinning method toner capable of reducing image density fluctuation and toner scattering over time during image formation, a two-component developer containing the two-component developer spinning method toner, and the two-component developer An image forming apparatus using a developer can be provided.

≪Two-component developer spinning toner≫
The spinning toner for a two-component developer of the present invention (hereinafter sometimes simply referred to as toner) is produced using a spinning method. The spinning toner is formed by stretching a toner component in a molten state into a fiber shape and cutting it to form particles (toner mother particles), and optionally applying an external addition treatment with fine particles (external additives). Manufactured.
Here, the toner component is a component contained in the toner, and a conventionally known toner component can be used as the toner component.

The toner contains a binder resin as an essential component.
The type of the binder resin is not particularly limited. For example, polystyrene resin, polyester resin, acrylic resin, styrene-acrylic copolymer, polyethylene resin, polypropylene resin, vinyl chloride resin. It is preferable to use a thermoplastic resin such as a polyamide resin, a polyurethane resin, a polyvinyl alcohol resin, a vinyl ether resin, an N-vinyl resin, or a styrene-butadiene resin.
Among these, polystyrene resins and / or polyester resins are preferable, and polystyrene resins are particularly preferable.

The polystyrene resin may be a homopolymer of styrene or a copolymer with another monomer (copolymerization monomer) copolymerizable with styrene.
As copolymerizable monomers, p-chlorostyrene; vinyl naphthalene; ethylene unsaturated monoolefins such as ethylene, propylene, butylene, and isobutylene; vinyl halides such as vinyl chloride, vinyl bromide, and vinyl fluoride; vinyl acetate, propion Vinyl esters such as vinyl acrylate, vinyl benzoate, vinyl butyrate; methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, dodecyl acrylate, n-octyl acrylate, 2-chloroethyl acrylate, acrylic (Meth) acrylic acid esters such as phenyl acid, methyl α-chloroacrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate; other acrylic acid derivatives such as acrylonitrile, methacrylonitrile, acrylamide; Vinyl ethers such as nylmethyl ether and vinyl isobutyl ether; Vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and methyl isopropenyl ketone; N-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidene, etc. N-vinyl compounds of These may be used alone or in combination of two or more with a styrene monomer.

Examples of the polyester-based resin include those obtained by condensation polymerization or co-condensation polymerization of an alcohol component and a carboxylic acid component.
The alcohol component is preferably a dihydric or higher alcohol component, specifically, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, Diols such as neopentyl glycol, 1,4-butenediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol Bisphenols such as bisphenol A, hydrogenated bisphenol A, polyoxyethylenated bisphenol A, polyoxypropylenated bisphenol A; sorbitol, 1,2,3,6-hexanetetro 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, diglycerol, 2-methylpropanetriol, 2- Examples include trivalent or higher alcohols such as methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5, -trihydroxymethylbenzene.
The carboxylic acid component is preferably a divalent or higher carboxylic acid component, and specific examples thereof include divalent or trivalent carboxylic acids, acid anhydrides or lower alkyl esters thereof. More specifically, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, malonic acid, or n-butyl succinic acid, n-butenyl succinic acid, isobutyl succinic acid, isobutenyl succinic acid, n-octyl succinic acid, n-octenyl succinic acid, n-dodecyl succinic acid, n-dodecenyl succinic acid, isododecyl succinic acid, isododece Divalent carboxylic acid such as alkyl or alkenyl succinic acid such as nylsuccinic acid; 1,2,4-benzenetricarboxylic acid (trimellitic acid), 1,2,5-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid Acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4- Tantricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra (methylenecarboxyl) methane, 1, Examples thereof include trivalent or higher carboxylic acids such as 2,7,8-octanetetracarboxylic acid, pyromellitic acid, and empole trimer acid.
Moreover, it is preferable that the softening point of a polyester-type resin is 110-150 degreeC, More preferably, it is 120-140 degreeC.

In order to improve the dispersibility of the material contained in the resin, the binder resin has at least one functional group selected from hydroxyl group, carboxyl group, amino group and glycidoxy (epoxy) group in the molecule. It is preferable to have.
Whether or not the resin has these functional groups can be confirmed using an FT-IR (Fourier transform infrared spectroscopy) apparatus. The functional group can be quantified by a titration method.
The binder resin having a functional group can be produced by performing polymerization using a monomer having a desired functional group as a monomer. Further, the functional group may be introduced into a predetermined resin by a conventionally known method.

The binder resin preferably has a glass transition point (Tg) in the range of 55 to 70 ° C. When the glass transition point of the binder resin is 55 ° C. or higher, the toner particles are hardly fused with each other, and the storage stability is improved. On the other hand, when the glass transition point of the binder resin is 70 ° C. or less, the toner fixability is improved.
The glass transition point of the binder resin can be obtained from the change point of specific heat using a differential scanning calorimeter (DSC).

The binder resin preferably has a mass average molecular weight (Mw) of 5,000 to 300,000, and more preferably 20,000 to 100,000.
Further, the binder resin preferably has a dispersity (Mw / number average molecular weight (Mn)) of 5 to 100, more preferably 10 to 50.
The Mw and Mn of the binder resin are determined by measuring the elution time from the column using a molecular weight measuring device (GPC) and comparing with a calibration curve prepared in advance using a standard polystyrene resin. Can do.
The binder resin preferably has two mass average molecular weight peaks (referred to as a low molecular weight peak and a high molecular weight peak). Specifically, the low molecular weight peak is in the range of 3,000 to 20,000, the other high molecular weight peak is in the range of 300,000 to 1,500,000, and Mw / Mn is 10 or more. Those are preferred. If the mass average molecular weight peak is within such a range, the toner can be easily fixed, and offset resistance can be improved. The binder resin having two mass average molecular weight peaks can be obtained, for example, by mixing a low molecular weight resin and a high molecular weight resin.

The binder resin is preferably a thermoplastic resin as described above from the viewpoint of good fixability. However, the amount of the crosslinked portion (gel amount) measured using a Soxhlet extractor is 10% by mass or less. A thermosetting resin may be used as long as the value is preferably in the range of 0.1 to 10% by mass. By introducing a partially crosslinked structure in this way, it is possible to further improve the storage stability, form retention, and durability of the toner without deteriorating the fixability.
Therefore, it is not necessary to use 100% by mass of the thermoplastic resin as the toner binder resin, and a part of the thermosetting resin may be used. Moreover, you may add a crosslinking agent.
Examples of the thermosetting resin include epoxy resins and cyanate resins. More specifically, one or more of bisphenol A type epoxy resin, hydrogenated bisphenol A type epoxy resin, novolac type epoxy resin, polyalkylene ether type epoxy resin, cycloaliphatic type epoxy resin, cyanate resin, etc. Combinations are listed.

The toner further contains a wax.
The wax is not particularly limited. For example, plant waxes such as carnauba wax, sugar wax, and wood wax; animal waxes such as beeswax, insect wax, whale wax, and wool wax; Fischer-Tropsch having ester in the side chain ( In the following, synthetic hydrocarbon waxes such as wax, polyethylene wax, and polypropylene wax may be mentioned. Whether or not the wax has an ester in the side chain can be confirmed by separating the wax from the toner and determining the ester value from the (saponification value)-(acid value) of the wax.
The wax preferably has an endothermic main peak in a range of 70 to 100 ° C. in an endothermic curve obtained by a differential scanning calorimeter. When the endothermic main peak is less than 70 ° C., toner blocking and hot offset may occur. On the other hand, when the endothermic main peak exceeds 100 ° C., low temperature fixability may not be obtained.

In the toner, the blending amount of the wax is preferably in the range of 0.1 to 20 parts by mass with respect to 100 parts by mass of the binder resin. When the blending amount of the wax is 0.1 parts by mass or more, the effects of the wax (releasing properties, offset resistance, etc.) are sufficiently obtained, and when the blending amount is 20 parts by mass or less, the blocking resistance is good. In addition, detachment of the wax from the toner can be prevented.
In particular, in order to set the absolute average value of the toner charge amount distribution q / d to 0.45 fC / μm to 0.6 fC / μm and the standard deviation of the charge amount distribution q / d to 0.24 or less, binding is performed. 0.1-20 mass parts is preferable with respect to 100 mass parts of resin, and 2-10 mass parts is more preferable.

The toner preferably further contains a colorant.
Examples of colorants include black pigments such as acetylene black, lanblack, and aniline black; black pigments such as yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, and navel. S Yellow, Naphthol Yellow S, Hansa Yellow G, Hansa Yellow 10G, Benzidine Yellow G, Benzidine Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG, Tartra Gin Lake; , Pyrazolone orange, vulcan orange, indanthrene brilliant orange RK, benzidine orange G, indanthrene brilliant orange GK; red pigment, Bengala, cad Umred, lead red, mercury cadmium sulfide, permanent red 4R, risol red, pyrazolone red, watching red calcium salt, lake red D, brilliant carmine 6B, eosin lake, rhodamine lake B, alizarin lake, brilliant carmine 3B; , Manganese Purple, Fast Violet B, Methyl Violet Lake; As Blue Pigment, Bitumen, Cobalt Blue, Alkaline Blue Lake, Victoria Blue Lake, Phthalocyanine Blue, Metal-free Phthalocyanine Blue, Phthalocyanine Blue Partial Chlorides, Fast Sky Blue, Induslen Blue BC; as a green pigment, chromium green, chromium oxide, pigment green B, malachite green lake, fanal yellow green G; As color pigments, zinc oxide, titanium oxide, antimony white, zinc sulfide; as a white pigment, baryta powder, barium carbonate, clay, silica, white carbon, talc, alumina white can be used.
In the toner, the blending amount of the colorant is preferably 1 to 20 parts by mass and more preferably 3 to 10 parts by mass with respect to 100 parts by mass of the binder resin.

The toner preferably further contains a charge control agent.
The type of the charge control agent is not particularly limited, but a charge control agent exhibiting positive charge is preferable. For example, an azine compound, a nigrosine compound, a metal salt of a carboxylic acid, an amine compound, a quaternary ammonium salt compound. And charge control resins.
More specifically, for example, pyridazine, pyrimidine, pyrazine, orthooxazine, metaoxazine, paraoxazine, orthothiazine, metathiazine, parathiazine, 1,2,3-triazine, 1,2,4-triazine, 1,3,5 -Triazine, 1,2,4-oxadiazine, 1,3,4-oxadiazine, 1,2,6-oxadiazine, 1,3,4-thiadiazine, 1,3,5-thiadiazine, 1,2,3,4 -Tetrazine, 1,2,4,5-tetrazine, 1,2,3,5-tetrazine, 1,2,4,6-oxatriazine, 1,3,4,5-oxatriazine, phthalazine, quinazoline, quinoxaline Azine Fast Red FC, Azin Fast Red 12BK, Azin Violet BO, Azin Brown 3G Direct dyes composed of azine compounds such as azine light brown GR, azine dark green BH / C, azine deep black EW, azine deep black 3RL; nigrosine compounds such as nigrosine, nigrosine salt, nigrosine derivatives; nigrosine BK, nigrosine NB, nigrosine Z Acid dyes comprising nigrosine compounds such as: naphthenic acid or higher fatty acid metal salts; alkoxylated amines; alkylamides; quaternary ammonium salts such as benzylmethylhexyldecylammonium and decyltrimethylammonium chloride; resins having quaternary ammonium salts or Examples include oligomers; charge control resins having a carboxylate salt; charge control resins having a carboxy group; charge control resins in which an amine compound is bonded to the resin.
The charge control agent is preferably colorless or white when the two-component developer is used for color image formation.

  In the toner, the blending amount of the charge control agent is preferably 0.5 to 20 parts by mass with respect to 100 parts by mass of the binder resin. In particular, in order to set the absolute average value of the toner charge amount distribution q / d to 0.45 fC / μm or more and 0.6 fC / μm or less, 6 to 15 parts by mass with respect to 100 parts by mass of the binder resin is preferable. 7-12 mass parts is more preferable.

The toner preferably further contains an external additive. Thereby, the fluidity of the two-component developer can be improved. Further, by adjusting the type and blending amount of the external additive, | q / d | and q / d standard deviation can be adjusted.
As external additives, conventionally known external additives such as inorganic oxides such as silica, alumina, tin oxide, titanium oxide, and strontium oxide; metal soaps such as calcium stearate; various resin powders and the like can be used.
The external additive is usually added by forming particles (toner base particles) formed by a spinning method using the above-described binder resin, wax, and the like, and then subjecting the toner base particles to an external addition treatment. The external addition treatment can be performed, for example, by adding an external additive to the toner base particles and stirring with a stirrer.
The blending amount of the external additive in the toner is preferably 0.3 to 4.0 parts by mass with respect to 100 parts by mass of the toner base particles. In particular, in order to set the absolute average value of the toner charge amount distribution q / d to 0.45 fC / μm or more and 0.6 fC / μm or less, 1.0 to 3.0 mass with respect to 100 mass parts of the binder resin. Part is preferred.

[Toner production method]
The production of toner by a spinning method includes, for example, a melt mixing step in which a toner raw material obtained by premixing each of the above-described toner components (binder, wax, colorant, charge control agent, etc.) is melt-mixed; It can be carried out by a fiberizing process in which the molten toner material obtained in the mixing process is extruded from a nozzle to form a fiber, and a particle forming process in which the toner material formed in a fiber is cut to produce columnar particles. .

Hereafter, each said process is demonstrated based on drawing.
“Melting and fiberizing process”
The melt mixing step and the fiberizing step include, for example, a uniaxial extruder 1 with a hopper 1A and a rotating screw 15 as a kneading member inside, a static mixer 2, and a static mixer 2 as shown in FIG. This is performed using an apparatus including a flow channel structure 3 having a multistage distribution flow channel 3A branched from the outlet of the gas flow.
A gear pump 4 driven by a motor 5 is disposed between the outlet of the uniaxial extruder 1 and the inlet of the stationary mixer 2.
Further, on the upstream side of the hopper 1A, a premixing device (for example, Hosokawa Micron Co., Ltd .: Cyclomix) 7 that premixes each toner component and uses it as a toner raw material is installed.
Although not shown in the uniaxial extruder 1, the static mixer 2, the flow path structure 3, and the gear pump 4, the toner material is heated to a temperature higher than the melting point of the binder resin, for example, about 130 ° C to 240 ° C. And a heater for reducing the viscosity.
An extrusion nozzle 6 is provided at each channel outlet of the final stage of the distribution channel 3A.
In the static mixer 2, as shown in FIG. 1, blade bodies 14 having curved surfaces twisted so as to form a spiral flow path are adjacent to each other along the flow direction of the toner material. The structure is such that a plurality (three in the example of FIG. 1) are provided while reversing the twist angle of the spiral, but the structure is not limited to this, and a known static mixer can be used.

In the above apparatus configuration, first, as shown in FIG. 1, when the toner raw material prepared by the premixing apparatus 7 is put into the uniaxial extruder 1 from the hopper 1A, it is heated by the heater to be in a molten state. And sent to the outlet side while being mixed.
The melted toner raw material sent out from the uniaxial extruder 1 is adjusted in pressure and extrusion amount by the gear pump 4, and then the flow path in the static mixer 2 and the multistage distribution flow path of the flow path structure 3. Mixing is facilitated while flowing through 3A. Therefore, each toner component is uniformly and finely dispersed in the toner raw material.
The molten toner material is extruded downward from the plurality of nozzles 6 to form a fibrous body 12.
The plurality of fibrous bodies 12 pushed out from the nozzles 6 are stretched by hot air blown from a drawing air blowing device (not shown) and then rapidly cooled by cold air from a blower fan.

Next, a large number of fibrous bodies 12 extruded from the nozzles are conveyed to the fiber cutting device 8 by the belt conveyor 11 as shown in FIG.
In the middle of conveyance, the many fibrous bodies 12 on the belt conveyor 11 are allowed to cool to room temperature and have an appropriate hardness. And these many fibrous bodies 12 arrive at the fiber cutting device 8 as a single-layer aggregate arranged in an orderly manner in the lateral direction.
As a means for conveying the fibrous body 12, in addition to the belt conveyor 11, a gas conveying means by an air flow having a constant flow velocity and a flow direction may be used.

"Particulate process"
In the particle forming step, as shown in FIG. 2, the fibrous body 12 conveyed by the belt conveyor 11 is cut by the fiber cutting device 8.
The fiber cutting device 8 includes a stationary blade 9 having an edge 9a orthogonal to the conveying direction of the fibrous body 12, a rotating blade 10 having a plurality of cutting blades 10a attached to a rotating shaft, and a motor that rotationally drives the rotating blade 10 ( (Not shown).
In the fiber cutting device 8, the fibrous body 12 is continuously supplied between the cutting blade 10a of the rotary blade 10 driven to rotate by a motor and the edge 9a of the fixed blade 9, and the cutting blade 10a and the fixed blade edge 9a. The fibrous body 12 is sequentially cut by the shearing action generated between the two and the columnar particles 13 are continuously produced.
Here, the cutting length of the fibrous body 12 (the length of the columnar particles 13) can be adjusted by the ratio of the conveying speed of the fibrous body 12 and the rotational speed of the rotary blade 10.

In the particle forming step, columnar particles having a desired particle size distribution can be produced by adjusting the cutting length when the fibrous body 12 is cut. If necessary, a classification step may be provided after the particle forming step. Good. Thereby, columnar particles having a narrower particle size distribution are obtained.
Moreover, it is preferable to perform the external addition process which adds an external additive to the produced columnar particle as mentioned above after the granulation process or the classification process.

In the present invention, the toner is a columnar particle produced by a spinning method as described above, and the absolute average value of the charge amount distribution q / d (hereinafter abbreviated as | q / d |) is 0. .45 fC (femtocoulomb) / μm to 0.6 fC / μm and the standard deviation of the charge distribution q / d (hereinafter abbreviated as q / d standard deviation) is 0.24 or less. is necessary. Thereby, the effect of the present invention can be obtained.
| Q / d | is preferably 0.45 fC / μm or more and 0.55 fC / μm or less. Further, the q / d standard deviation is preferably as small as possible.
Here, q in the charge amount distribution q / d represents the charge amount of the toner, and d represents the volume average particle diameter.
The | q / d | and q / d standard deviation of the toner are measured using an espart analyzer EST-3 (manufactured by Hosokawa Micron). This device is a particle charge amount distribution measuring device capable of simultaneously measuring the charge amount and particle size of individual particles in real time, and it is possible to obtain | q / d | and q / d standard deviation by this device. .
Specifically, about 5 g of toner is attached to the magnet holder, the magnet holder is set on an E-SPART analyzer (EST-3, manufactured by Hosokawa Micron), and the toner in the magnet holder at 0.05 MPa of nitrogen gas. The q / d number distribution of 3000 toners is obtained by spraying on the part and applying +0.05 kV to the measuring device. At this time, the distance between the discharge nozzle of nitrogen gas and the measurement sample developer installed in the magnet holder is set within 8.0 mm so as to be sprayed.
An example of the charge amount distribution curve measured by the apparatus is shown in FIG.
In the case of toner produced by a pulverization method, | q / d | is usually about 0.3 to 0.5 fc / μm, and q / d standard deviation is about 0.3 to 0.6.

The | q / d | and q / d standard deviation of the toner can be adjusted by the type of toner component to be blended in the toner, the toner production method, the kneading process conditions, and the like.
For example, | q / d | can be increased by increasing the amount of the charge control agent. Further, | q / d | can be increased by increasing the blending amount of the external additive or decreasing the blending amount of the wax.
In addition, the q / d standard deviation of the toner can be reduced by reducing the amount of the wax blended. Also, in the melt mixing process, the toner components are more uniformly mixed, and the dispersibility of the toner components in the obtained columnar particles. The q / d standard deviation can be reduced, particularly by finely and uniformly dispersing the wax.
The dispersibility of each toner component in the melt mixing step is, for example, the temperature in the uniaxial extruder 1, the static mixer 2, the flow channel structure 3 and the like shown in FIG. It can be adjusted by adjusting the structure, the number of stages of the distribution channel 3A, and the like.
The dispersibility of the toner can be determined by the average dispersion diameter of the wax. The average dispersion diameter of the wax is obtained by, for example, cutting the toner with a microtome and analyzing the image obtained by photographing with a transmission electron microscope (TEM), thereby obtaining the average dispersion diameter (μm) of the wax. be able to.
In the present invention, the average dispersion diameter of the wax is preferably 0.2 to 2.0 μm, more preferably 0.3 to 1.2 μm, and still more preferably 0.2 to 0.5 μm.

According to the spinning toner for a two-component developer of the present invention, an electrostatic latent image is formed on the surface of the photoreceptor, a magnetic brush is formed on the surface of the magnetic roll with the two-component developer, and the magnetic brush Then, only the toner is transferred to the surface of a developing roll disposed facing the photoconductor to form a toner layer, and the toner is scattered from the toner layer to develop the electrostatic latent image on the surface of the photoconductor as a toner image. It is possible to reduce image density fluctuations and toner scattering over time when an image is formed by an image forming apparatus of a type (image forming apparatus of a touchdown development type).
The reason why the above effect can be obtained is as follows.
That is, the touch-down development method is a method for developing an electrostatic latent image by forming a toner layer on a developing roll with a magnetic brush. In this method, only toner that has reached a predetermined charge amount forms a toner layer, and therefore toner with extremely low charge cannot exist on the developing roll. Therefore, toner scattering from the developing roll is likely to occur.
For example, in the case of the one-component development method, the toner is forcibly conveyed near the developing roll and the toner layer is forcibly formed by a regulating blade or the like, so the influence of the toner charge amount is extremely large. Absent. However, in the touch-down development method, in order to form an image, the toner of the two-component developer is rubbed and charged, and the toner layer is formed on the developing roll by electrically flying the toner. It is necessary to selectively move the toner in two steps of developing the electrostatic development by flying the toner from the toner layer to the electrostatic latent image on the photoreceptor. For this reason, the image density is greatly influenced by the charge amount of each toner and its variation, that is, the charge amount distribution.
Further, not only the touchdown development method but also the one-component development method and the two-component development method, toner scattering and image density fluctuation are affected by the toner manufacturing method. For example, as described above, the pulverized toner is likely to cause toner scattering and has a wide particle size distribution, so that the image density is likely to vary. In particular, in the touch-down development method, only the toner is selectively moved from the two-component developer, so the influence of the particle size distribution is large.
That is, in the touch-down development method, in order to improve image density fluctuation and toner scattering, a toner having a sharp particle size distribution and a sharp charge amount distribution is required as compared with other development methods.

Looking at conventional toners focusing on these points, the spinning toner shears the toner composition that has been stretched into a fibrous shape, so that the area of the fracture surface of the toner is almost equal. . The stretching direction also has a slight variation in length compared to the fractured surface, but its distribution is sharp and sharp compared to the grinding method. The charge control agent is exposed on the fracture surface, the charged sites are segregated on the fracture surface, and the area of the surface where the charged sites of the particles are substantially equal, the saturation charge amount is almost equal. Compared to the pulverization method, the charge amount distribution tends to be extremely sharp. Therefore, it is presumed that by using the spinning toner as a two-component developer in the touch-down development method, the particle size distribution of the toner in the developer after the durability can be kept constant, and the fluctuation in image density can be suppressed. .
However, in the spinning toner, exposure of the wax that broadens the charge amount distribution and the charge control agent that increases the charge amount is small at the toner interface. To be precise, the wax and the charge control agent are exposed on the fracture surface, and the charged sites are segregated on the fracture surface. That is, there are many charged sites on the fracture surface, and there are not many on the other peripheral surfaces. Therefore, there are few chances of friction with the carrier which is an auxiliary charging member, and the charge amount is lower than that of the pulverized toner. The low charge amount is a serious problem in the touch-down development method as described above.
In contrast, since the toner of the present invention is a spinning method toner, the particle size distribution is sharp, and | q / d | is 0.45 fC / μm to 0.6 fC / μm and q / d standard deviation is 0. The above effects can be obtained because the toner has a charge amount of individual particles of less than.

≪Two-component developer≫
The two-component developer of the present invention comprises the spinning toner for a two-component developer of the present invention and a carrier.

<Carrier>
Various conventionally known carriers can be used as the carrier.
Examples of carrier core materials include particles of magnetic materials such as iron, oxidized iron, reduced iron, magnetite, copper, silicon steel, ferrite, nickel, and cobalt; alloys of these magnetic materials with manganese, zinc, aluminum, and the like Particles of alloys such as iron-nickel alloy and iron-cobalt alloy; titanium oxide, aluminum oxide, copper oxide, magnesium oxide, lead oxide, zirconium oxide, silicon carbide, magnesium titanate, barium titanate, lithium titanate, titanium Ceramic particles such as lead oxide, lead zirconate, lithium niobate; particles of high dielectric constant materials such as ammonium dihydrogen phosphate, potassium dihydrogen phosphate, Rochelle salt; resin in which these particles are dispersed in resin The thing which consists of carrier core materials, such as a carrier, is mentioned.

Further, a resin coating layer may be provided on the carrier core material.
Examples of the resin constituting the resin coating layer of the carrier include (meth) acrylic polymers, styrene polymers, styrene- (meth) acrylic copolymers, olefin polymers (polyethylene, chlorinated polyethylene, polypropylene, etc.) , Polyvinyl chloride, polyvinyl acetate, polycarbonate, cellulose resin, polyester resin, unsaturated polyester resin, polyamide resin, polyurethane resin, epoxy resin, silicone resin, fluororesin (polytetrafluoroethylene, polychlorotrifluoroethylene, polyfluoride) Various conventionally known resins can be used for coating carriers such as vinylidene), phenol resin, xylene resin, diallyl phthalate resin, polyacetal resin, amino resin and the like. These may be used alone or in admixture of two or more.
The resin coating layer may contain additives for adjusting the properties of the resin coating layer, such as silica, alumina, carbon black, fatty acid metal salt, silane coupling agent, titanate coupling agent, as necessary. You can also.
The film thickness of the resin coating layer may be the same as that of the conventional one, and is not particularly limited. Specifically, the resin coating layer is expressed in terms of a coating amount on the carrier core material, and is 0.01 to 10% by mass, particularly 0. The coverage is preferably from 5 to 5% by mass.

  The average particle diameter of the carrier is preferably in the range of 10 to 200 μm, particularly preferably in the range of 30 to 150 μm.

The two-component developer can be produced by mixing the toner and the carrier.
In the two-component developer, the ratio between the toner and the carrier is not particularly limited, and may be the same as that of the conventional two-component developer. Generally, the blending amount of the toner is in the range of 3 to 15 parts by mass with respect to 100 parts by mass of the carrier, and preferably 5 to 10 parts by mass.

  The two-component developer of the present invention forms an electrostatic latent image on the surface of the photoreceptor in the image forming apparatus, forms a magnetic brush with the two-component developer on the surface of the magnetic roll, and uses only the toner from the magnetic brush. Is transferred to the surface of a developing roll facing the photoconductor to form a toner layer, and the toner is scattered from the toner layer to develop the electrostatic latent image on the surface of the photoconductor as a toner image, so-called It is used for an image forming apparatus of a touchdown development system.

≪Image forming device≫
The image forming apparatus of the present invention is a touch-down developing type image forming apparatus in which the two-component developer of the present invention is used.
The image forming apparatus of the present invention includes a photoreceptor on which an electrostatic latent image is formed on a surface, and a developing unit that develops the electrostatic latent image on the photoreceptor, and the developing unit includes toner and a carrier. A magnetic roll having a magnetic brush formed on its surface by the two-component developer, and a developing roll having a toner layer formed on the surface by the toner transferred from the magnetic brush. An image forming apparatus having an apparatus configuration in which the photosensitive member is disposed to face each other is exemplified.

Hereinafter, an embodiment of an image forming apparatus of the present invention will be described with reference to FIG.
The image forming apparatus 20 of the present embodiment includes a drum-shaped photoconductor 21, a charging unit 22 that charges the surface of the photoconductor 21, and an exposure unit 23 that exposes the surface of the photoconductor 21 to form an electrostatic latent image. And developing means 24 for developing the electrostatic latent image as a toner image by attaching toner to the electrostatic latent image, and transferring the toner image from the photosensitive member 21 to a transfer target moving on the endless belt 25. A transfer unit 26 and a cleaning unit 27 for cleaning the surface of the photoreceptor are provided.

As the photosensitive member 21, an inorganic photosensitive member such as selenium or amorphous silicon; an organic photosensitive member in which a single layer or a laminated photosensitive layer containing a charge generating agent, a charge transporting agent, a binder resin, or the like is formed on a conductive substrate. Etc.
Examples of the charging means 22 include a scorotron system, a charging roll, and a charging brush.
As the exposure unit 23, the transfer unit 26, and the cleaning unit 27, known ones may be used.

The developing means 24 includes a magnetic roll 28 (developer carrying member) on which a magnetic brush is formed by a two-component developer, and toner transferred from a magnetic brush (not shown) formed on the magnetic roll 28. A developing roll 29 (toner carrier) on which a toner layer (not shown) is formed, a power supply 30 for applying a direct current (DC) bias to the magnetic roll 28, and a direct current (DC) bias to the developing roll 29. , A power supply 34 for applying an alternating current (AC) bias to the developing roll 29, a regulating blade 36 for keeping the height of the magnetic brush formed on the magnetic roll 28 constant, and two-component development Supplied from the stirring mixer 40 through the partition plate 42, the container 38 for storing the agent or toner, the stirring mixer 40 for charging the toner of the two-component developer. The component developer comprises a paddle mixer 44 is supplied to the magnetic roll 28 with stirring, magnetic roll 28, a developing roll 29, and a frame body 46 for accommodating the agitation mixer 40 and paddle mixers 44.
The magnetic roll 28 has a plurality of fixed magnets disposed therein, and the sleeve-like magnetic roll 28 can rotate around the fixed magnet.
Further, the developing roll 29 is disposed on the opposite side of the photosensitive member 21.

As an image forming method using the image forming apparatus of the touchdown development method as described above, for example,
A charging step for charging the surface of the photoreceptor;
Exposing the surface of the photoreceptor to form an electrostatic latent image; and
A magnetic brush is formed by a two-component developer comprising a toner and a carrier, only the toner is separated from the magnetic brush to form a toner layer, and the toner in the toner layer is transferred to an electrostatic latent image on the surface of the photoreceptor. And a developing step of forming a toner image by attaching the toner image to the toner image.

Hereinafter, an image forming method using the touch-down development type image forming apparatus will be described with reference to an example using the image forming apparatus 10 shown in FIG.
First, the surface of the photoreceptor 21 is charged by the charging means 22 (charging process). Next, the surface of the photoconductor 21 is exposed by the exposure means 23 to form an electrostatic latent image (exposure process).
On the other hand, in the developing means 24, the toner of the two-component developer is charged by the stirring mixer 40, the two-component developer is supplied to the magnetic roll 28 by the paddle mixer 44, and is carried on the surface of the magnetic brush. Then, only the toner is transferred from the magnetic brush to the surface of the developing roll 29 to form a toner layer on the surface of the developing roll 29.
Then, the toner is ejected from the toner layer of the developing roll 29, and the toner is attached to the electrostatic latent image on the photosensitive member 21 to develop the electrostatic latent image as a toner image (developing step). Next, the toner image is transferred from the photoconductor 21 to the transfer target moving on the endless belt 25 by the transfer means 26 (transfer process). Separately, the surface of the photoreceptor 21 after the transfer process is cleaned using a cleaning unit 27.
The above steps are repeated.
After supplying the two-component developer to the container 38 for the first time, only the toner needs to be replenished. In this case, the toner supplied from the container 38 is mixed with the carrier by the agitating mixer 40 to form a two-component developer.

  The image forming apparatus of the present invention can be used as a copying machine, a facsimile, a laser beam printer, a complex machine of these, and the like.

The evaluation test of the present invention will be described below based on examples.
Needless to say, the following description exemplifies the present invention, and the scope of the present invention is not limited to the following description.
<Example 1>
First, a fibrous body was produced by the following procedure using the apparatus having the configuration shown in FIG.
Binder resin (styrene acrylic resin, manufactured by Sekisui Chemical Co., Ltd., Mw4000 polystyrene resin) 85 parts by mass, carbon black (MA-100, manufactured by Mitsubishi Chemical Corporation) 5 parts by mass, charge control resin (control agent Q, Fujikura Kasei Co., Ltd.) 8 parts by mass) and 5 parts by mass of FT wax (FT-100, manufactured by Nippon Seiki Co., Ltd., endothermic main peak 90 ° C.) are mixed by the premixing device 7, and the mixture is fed from the hopper 1A to the uniaxial extruder 1 To obtain a fibrous body having a diameter of about 8 μm by passing through the stationary mixer 2 and the distribution channel 3A and extruding from the nozzle 6.
Next, as shown in FIG. 2, the obtained fibrous body is allowed to cool at room temperature while being conveyed by a belt conveyor 11, and is cut by a fiber cutting device 8, so that the volume average particle diameter is reduced. About 8 μm cylindrical particles were obtained.
Next, 1.2 parts by mass of silica (RA-200H: manufactured by Nippon Aerosil Co., Ltd.) and 0.8 parts by mass of titanium oxide (ST-100, manufactured by Titanium Industry Co., Ltd.) were added to 100 parts by mass of the particles using a Henschel mixer. A nonmagnetic positively chargeable toner was prepared by externally adding and adhering to the surface of the particles.

With respect to the obtained toner, the charge amount distribution (| q / d | and q / d standard deviation) was measured by the following procedure. The results are shown in Table 1.
About 5 g of toner is attached to the magnet holder, and the magnet holder is set on an E-SPART analyzer (EST-3, manufactured by Hosokawa Micron Corporation), and nitrogen gas is sprayed onto the toner part of the magnet holder at 0.05 MPa. A flow of +0.05 kV was applied to the measuring device to obtain a q / d number distribution of 3000 toners. At this time, the distance between the discharge nozzle of nitrogen gas and the measurement sample developer installed in the magnet holder was set within 8.0 mm and sprayed.

<Example 2>
A toner was obtained in the same manner as in Example 1 except that the amount of charge control resin (control agent Q: manufactured by Fujikura Kasei Co., Ltd.) was changed to 6 parts by mass.
For the obtained toner, the charge amount distribution was measured in the same manner as in Example 1. The results are shown in Table 1.

<Example 3>
A toner was obtained in the same manner as in Example 1 except that the amount of silica (RA-200H: manufactured by Nippon Aerosil Co., Ltd.) externally added to the particles was changed to 1.5 parts by mass.
For the obtained toner, the charge amount distribution was measured in the same manner as in Example 1. The results are shown in Table 1.

<Comparative Example 1>
A toner was obtained in the same manner as in Example 1 except that the amount of charge control resin (control agent Q: manufactured by Fujikura Kasei Co., Ltd.) was changed to 5 parts by mass.
For the obtained toner, the charge amount distribution was measured in the same manner as in Example 1. The results are shown in Table 1.

<Comparative example 2>
A toner was obtained in the same manner as in Example 1 except that the amount of FT wax (FT-100, manufactured by Nippon Seiki Co., Ltd.) was changed to 8 parts by mass.
For the obtained toner, the charge amount distribution was measured in the same manner as in Example 1. The results are shown in Table 1.

<Comparative Example 3>
In the same manner as in Example 1, toner was manufactured by a pulverization method using a toner raw material melted by the uniaxial extruder 1.
For the obtained toner, the charge amount distribution was measured in the same manner as in Example 1. The results are shown in Table 1.

<Comparative Example 4>
A toner was obtained in the same manner as in Comparative Example 3 except that the amount of charge control resin (control agent Q: manufactured by Fujikura Kasei Co., Ltd.) was changed to 3 parts by mass.
For the obtained toner, the charge amount distribution was measured in the same manner as in Example 1. The results are shown in Table 1.

<Examples 4-6, Comparative Examples 5-8>
A two-component developer is prepared by mixing 5 parts by mass of the toner obtained in Examples 1 to 3 and Comparative Examples 1 to 4 with 95 parts by mass of ferrite carrier (average particle size 80 μm, silicone resin coat, manufactured by Powdertech). Produced.
The following evaluation was performed on the produced two-component developer. The results are shown in Table 2.
(Image density evaluation)
Using a touchdown development machine (FS-8000C machine made by Kyocera Mita), a durability test of 10,000 sheets (original density 4% continuous printing) is performed, and the durability test starts (initial stage) and ends ( In each of (after durability), the image density ID of the black solid portion of the copy image was measured using a reflection densitometer (manufactured by Tokyo Denshoku Co., Ltd., model number TC-6D), and evaluated according to the following criteria.
[Criteria]
1.35 ≦ ID… ○ (good)
1.30 ≦ ID <1.35... (Defect)
ID <1.30 ... x (bad)

(Evaluation of toner scattering)
After the endurance of the image density evaluation, the adhering toner (scattered toner) on the lower shield part of the developing roll of the touchdown developing machine used is sucked with a pump and collected on a filter having an opening of 1 μm and its mass (scattered) Amount) was measured and evaluated according to the following criteria.
[Criteria]
Spatter amount ≦ 50 mg… ○ (good)
50 mg <scattered amount ≦ 150 mg ... △ (defective)
150 mg <scattered amount ... × (bad)

(Particle size distribution)
The electrolyte solution was added to about 0.5 g of the developer at the initial stage of image density evaluation and after the endurance test, the carrier was removed by a magnet, and the average particle size d50 of the remaining toner (volume average particle size (vol. Μm)). Was measured by the Coulter counter method (Multisizer II (manufactured by Beckman Coulter, Inc.), measurement conditions: aperture diameter 100 μm, particle count 100,000). The difference from the particle size (Δd50) was determined and evaluated according to the following criteria.
[Criteria]
Δd50 ≦ 0.3 vol. μm… ○ (good)
0.3 vol. μm <Δd50 ≦ 0.5 vol. μm ... △ (defect)
0.5 vol. μm <Δd50 ... x (bad)

As is apparent from the above results, a toner produced by a spinning method and having a | q / d | of 0.45 fC / μm to 0.6 fC / μm and a q / d standard deviation of 0.24 or less was used. The two-component developers of Examples 4 to 6 were good in both image density and toner scattering. Further, the Δd50 of the toner was small, and it was confirmed that the difference in particle size distribution before and after the durability test was small.
On the other hand, the two-component developer of Comparative Example 5 using toner having | q / d | of less than 0.45 fC / μm did not show good toner scattering. This is presumably because the amount of charge of the toner was small and the amount of reverse charge toner increased during the durability test. Moreover, it was confirmed that Δd50 was large and the particle size distribution was greatly changed. This is presumably because small-diameter toner (fine toner) having a relatively high charge remained in the developer.
Further, the two-component developer of Comparative Example 6 using a toner having a q / d standard deviation exceeding 0.24 was poor in both image density and toner scattering, and particularly in toner scattering. This is presumably because the amount of wax was large, so that the wax oozed out during the durability test and caused toner charging failure.
In addition, the two-component developers of Comparative Examples 7 to 8 using a pulverized toner had extremely poor evaluation of image density and toner scattering.

The two-component developer using the spinning toner for two-component developer of the present invention forms an electrostatic latent image on the surface of the photoreceptor, forms a magnetic brush with the two-component developer on the surface of the magnetic roll, From the magnetic brush, only the toner is transferred to the surface of a developing roll disposed facing the photoconductor to form a toner layer, and the toner is scattered from the toner layer to form an electrostatic latent image on the surface of the photoconductor. It is used in an image forming apparatus that develops as an image (touch-down development system).
According to the image forming apparatus using the two-component developer, it is possible to reduce image density fluctuation and toner scattering with time during image formation.

FIG. 6 is a process diagram illustrating a part of a process for producing toner. FIG. 6 is a process diagram illustrating a part of a process for producing toner. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus. It is a graph which shows an example of a charge amount distribution curve.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Uniaxial type extruder, 2 ... Static mixer, 3 ... Flow path structure, 4 ... Gear pump, 5 ... Motor, 6 ... Nozzle, 7 ... Pre-mixing device, 8 ... Fiber cutting device, 9 ... Fixed blade, 10 DESCRIPTION OF SYMBOLS ... Rotary blade, 11 ... Belt conveyor, 12 ... Fibrous body, 13 ... Columnar particle, 20 ... Image forming apparatus, 21 ... Photoconductor, 22 ... Charging means, 23 ... Exposure means, 24 ... Developing means, 25 ... Endless belt , 26 ... transfer means, 27 ... cleaning means, 28 ... magnetic roll, 29 ... developing roll, 30 ... power supply, 32 ... power supply, 34 ... power supply, 36 ... regulating blade, 38 ... container, 40 ... stirring mixer, 42 ... partition Board, 46 ... Frame

Claims (3)

An electrostatic latent image is formed on the surface of the photoconductor, a magnetic brush is formed on the surface of the magnetic roll with a two-component developer, and only the toner is transferred from the magnetic brush to the surface of the photoconductor. A two-component developer spinning method toner used in an image forming apparatus that develops an electrostatic latent image on the surface of a photoreceptor as a toner image Because
The absolute value of the charge amount distribution q / d is 0.45 fC / μm or more and 0.6 fC / μm or less, and the standard deviation of the charge amount distribution q / d is 0.24 or less. Spinning toner for developer.   A two-component developer comprising the spinning toner for a two-component developer according to claim 1 and a carrier. An electrostatic latent image is formed on the surface of the photoconductor, a magnetic brush is formed on the surface of the magnetic roll with a two-component developer, and only the toner is transferred from the magnetic brush to the surface of the photoconductor. An image forming apparatus that develops an electrostatic latent image on the surface of a photoreceptor as a toner image by forming a toner layer by transferring the toner to
The image forming apparatus according to claim 2, wherein the two-component developer according to claim 2 is used as the two-component developer.

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