JP2008139469A - Toner for magnetic two-component developer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner for a magnetic two-component developer capable of achieving good gradation property and good developing property by devising the shape of toner particles, etc., without coordinating the process side. <P>SOLUTION: When a magnetic two-component developer passes through a brush clipping plate 32, a toner and a magnetic carrier are rubbed together and the toner is charged. When the magnetic two-component developer comes into contact with a surface of an image carrier 20, a toner image is formed on the image carrier 20 and an electrostatic latent image is developed. The toner of the magnetic two-component developer used for development contains cylindrical toner particles produced by drawing a molten toner component in a cylindrical fiber form and carrying out cutting, wherein the cylindrical toner particles have a standard deviation of a particle size distribution of ≤1.20 μm. The value given by dividing a cylinder length of the cylindrical toner particles by a cylinder cross-section diameter thereof is 1.0-2.0. The cylindrical toner particles have an average circularity of 0.890-0.920. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a toner used for a magnetic two-component developer containing a toner and a magnetic carrier.

In an image forming process in an electrophotographic image forming apparatus, as a developer used for developing an electrostatic image, a magnetic two-component developer composed of a toner and a magnetic carrier is typical, and development by a two-component development system is performed. Used for.
In this two-component development system, for example, the magnetic two-component developer is supplied to a roller-shaped developer carrying member disposed opposite to the drum-shaped image carrier. For example, the developer carrying member includes a magnet having a large number of magnetic poles. For this reason, a magnetic two-component developer formed in a magnetic brush shape is attached to the peripheral surface of the developer carrying member. In this developer carrying member, a layering plate for regulating the layer thickness of the developer and charging the toner is arranged at a certain distance from the surface of the developing roller. When the toner passes through the toner, the toner and the magnetic carrier rub against each other so that the toner is charged. When the magnetic brush-like magnetic two-component developer comes into contact with the photoreceptor, only the toner in the magnetic two-component developer adheres to the photoreceptor, and a toner image is formed on the photoreceptor. The toner remaining on the photoconductor after the toner image is transferred is removed by a cleaning device.

In recent years, it has been desired that the gradation of the formed image is good. In order to improve the gradation of the formed image, for example, as disclosed in Patent Document 1, a method for improving the gradation of the formed image by devising the size of the photosensitive drum and the developing sleeve has been proposed.
Japanese Patent Laid-Open No. 2005-164875

However, it is desirable that the gradation and developability can be improved only by improving the toner used in the magnetic two-component developer, particularly the magnetic two-component developer, regardless of adjustment on the process side.
The present invention provides a toner for a magnetic two-component developer capable of realizing good gradation and good developability by devising the shape of the toner particles and the like regardless of adjustment on the process side. Objective.

The invention according to claim 1 is obtained by externally adding fine particles to cylindrical toner particles produced by stretching and cutting a toner component in a molten state into a cylindrical fiber shape. A toner for magnetic two-component developer, having a standard deviation (SD value) of distribution of 1.20 μm or less.
The toner for magnetic two-component developer has a relatively sharp particle size distribution with a standard deviation of the particle size distribution of the toner particles being 1.20 μm or less. In other words, the toner particles have the same size. Therefore, the charge amount of each toner particle becomes substantially uniform during friction charging. As a result, good gradation and good developability can be realized.

When the standard deviation of the particle size distribution of the toner particles exceeds 1.20 μm, the sizes of the toner particles become uneven, the ratio of excessively charged or poorly charged toner increases, and the charge amount of each toner particle varies. For this reason, gradation and developability are not good.
The invention according to claim 2 is obtained by externally adding fine particles to cylindrical toner particles produced by stretching and cutting a toner component in a molten state into a cylindrical fiber shape. A toner for magnetic two-component developer, wherein a value obtained by dividing a length by a diameter of a cylindrical cross section is 1.0 or more and 2.0 or less.

According to this configuration, the adhesive force between the cylindrical toner particles and the magnetic carrier can be properly maintained. For this reason, the cylindrical toner is favorably moved toward the image carrier. As a result, good gradation and good developability can be realized.
In the magnetic two-component developer, when the value obtained by dividing the cylinder length by the cylinder cross-sectional diameter is less than 1.0, the ratio of the cut surface to the entire outer surface of the cylindrical toner particle is high, and the cylindrical toner particle is at this cut surface. It tends to adhere to the magnetic carrier, and the adhesive force between the cylindrical toner particles and the magnetic carrier becomes too strong. This makes it difficult for the toner to move toward the image carrier. When the value obtained by dividing the cylinder length by the cylinder cross-sectional diameter exceeds 2.0, the ratio of the peripheral surface to the entire outer surface of the cylindrical toner particles is high, and the cylindrical toner particles easily adhere to the magnetic carrier on this peripheral surface. The adhesion between the cylindrical toner particles and the magnetic carrier becomes too strong. This makes it difficult for the toner to move toward the image carrier. Thereby, gradation and developability are not good.

The invention according to claim 3 is obtained by externally adding fine particles to cylindrical toner particles prepared by stretching and cutting a toner component in a molten state into a cylindrical fiber shape. A toner for magnetic two-component developer, having a circularity of 0.890 or more and 0.920 or less.
According to this configuration, the adhesive force between the cylindrical toner particles and the magnetic carrier can be properly maintained. For this reason, the toner appropriately moves toward the image carrier. Thereby, good gradation and good developability can be realized.

  In the magnetic two-component developer, if the average circularity of the cylindrical toner particles is less than 0.890, the adhesive force between the cylindrical toner particles and the magnetic carrier becomes too weak, and the toner and the magnetic carrier are easily pulled. There arises a problem that toner is scattered by peeling off. When the average circularity of the cylindrical toner particles exceeds 0.920, the adhesive force between the cylindrical toner particles and the magnetic carrier becomes too strong, and the toner becomes difficult to move toward the image carrier. On the other hand, if the circularity exceeds 0.920, the toner slips out of the cleaning device, resulting in poor cleaning properties.

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
FIG. 1 is a schematic diagram showing a configuration of an image forming mechanism 100 in which image formation is performed using a magnetic two-component developer including a magnetic two-component developer toner according to an embodiment of the present invention.
Referring to FIG. 1, an image forming mechanism 100 includes a cylindrical image carrier 20, a charger 21 for charging the surface of the image carrier 20, and an image carrier 20 charged by the charger 21. An exposure device 22 for exposing the surface in accordance with a created image; a developing device 23 for supplying a magnetic two-component developer to the image carrier 20 and developing an electrostatic latent image by exposure; and an image carrier A transfer device 24 for transferring the toner image formed on the surface of the image 20 to the paper, and a cleaning device 25 for removing the toner remaining on the surface of the image carrier 20 after the toner image is transferred to the paper. And a static eliminator 26 for neutralizing the surface of the photosensitive drum 2 after the toner image is transferred. The charger 21, the exposure device 22, the developing device 23, the transfer device 24, the cleaning device 25, and the static eliminator 26 are sequentially arranged along the rotation direction of the image carrier 20 (direction indicated by an arrow 27).

  The developing device 23 includes a developing tank 30 that stores a magnetic two-component developer. A cylindrical developer carrier 31 is rotatably mounted inside the developing tank 30 so as to face the image carrier 20. The developer carrier 31 is formed as a magnet roller having a magnetic pole. For this reason, a magnetic brush made of a magnetic two-component developer is formed on the peripheral surface of the developer carrier 31.

  The developing device 23 also includes a trimming plate 32 for regulating the thickness of the magnetic two-component developer attached to the peripheral surface of the developer carrier 31 in the form of a magnetic brush. The panning plate 32 is arranged at a certain distance from the surface of the developer carrier 31. Therefore, when the magnetic two-component developer passes through the panning plate 32, the toner and the magnetic carrier are separated. The toner is charged by friction with each other. When the magnetic brush-like magnetic two-component developer comes into contact with the surface of the image carrier 20, the toner in the magnetic brush adheres to the image carrier 20 and a toner image is formed on the image carrier 20. As a result, the electrostatic latent image carried on the image carrier 20 is developed. The magnetic carrier is not consumed by the development, but is collected in the developing tank 30 as it is and mixed with the toner again to be used.

The cleaning device 25 includes a cleaning blade 25 </ b> A that contacts the peripheral surface of the image carrier 20 and scrapes off toner adhering to the peripheral surface of the image carrier 20.
The magnetic two-component developer contains a toner and a magnetic carrier. The toner includes a cylindrical toner produced by a manufacturing method called a melt blown method described below. The melt blown method is described in detail, for example, in JP-A-2006-106236.

In this melt blown method, there are a kneading step for kneading the toner raw material in a molten state, a fiberizing step for forming the molten toner kneaded in the molten state into a fiber shape, and a cutting step for cutting the toner formed in the fiber shape. It is executed in order.
2 and 3, in the kneading step, the toner material is kneaded using the extruder 1. The toner raw material includes a binder resin, a colorant, a charge control agent, and a release agent. These toner raw materials were preliminarily mixed by a premixing device (for example, Hosokawa Micron Co., Ltd .: Cyclomix). Later, it is given to the extruder 1 via the hopper 1A. The extruder 1 is provided with a heater (not shown) for heating the toner material and a rotary screw 15 as a kneading member for kneading the toner material. The toner material applied to the extruder 1 is heated by a heater to be in a molten state, and the molten toner is kneaded by the rotary screw 15 at a predetermined kneading temperature (for example, 140 ° C.). The extruder 1 is connected to a stationary mixer 2 via a gear pump, and the molten toner kneaded by the extruder 1 is fed to the stationary mixer 2.

  The stationary mixer 2 has a plurality of blade bodies 14 each having a twisted curved surface, and a spiral flow path is defined by the plurality of blade bodies 14 therein. The molten toner kneaded by the extruder 1 is further kneaded by the rotation of the blade body 14. Thereby, in the static mixer 2, each component of the toner raw material is held in a state of being uniformly finely dispersed. In the static mixer 2, the molten toner is held at a temperature higher than the kneading temperature (180 ° C.). The gear pump 4 is for adjusting the amount of molten toner pushed out from a nozzle 6 described later, and is driven by a motor 5, for example. Next, it moves to a fiberization process.

  The stationary mixer 2 is connected to a flow channel structure 3 having a multistage distribution flow channel 3A. The distribution channel 3A is supplied with molten toner in a kneaded state from the stationary mixer 2, and this molten toner is further heated (not shown) by a heater (not shown) provided in the channel structure 3. For example, it is heated to 215 ° C. and pushed out from the nozzle 6 provided at the flow path outlet of each distribution flow path 3A.

The molten toner pushed out from each nozzle 6 is in the form of a fiber, and this fibrous molten toner is stretched by hot air (for example, 215 ° C.) blown from a drawing air blowing device (not shown) and then blown with cold air. Is rapidly cooled to form the fibrous toner 12.
Next, a cutting process for cutting the fibrous toner 12 will be described. As shown in FIG. 3, the fibrous toner 12 formed by being extruded from the nozzle 6 is transported to the cutting device 8 by the transport device 11. The cutting device 8 includes a fixed blade 9 extending in a direction perpendicular to the conveying direction of the fibrous toner 12 conveyed on the conveying device 11 and a rotary blade 10 that is rotationally driven by a motor (not shown). When the fibrous toner 12 is continuously supplied between the fixed blade 9 and the rotary blade 10, the fibrous toner is generated by a shearing action generated between the edge 9a of the fixed blade 9 and the cutting blade 10a of the rotary blade 10. 12 are sequentially cut to produce cylindrical toner particles 13 continuously.

At this time, the cylindrical length L of the cylindrical toner particles 13 (see FIG. 4) can be adjusted by the ratio of the conveying speed of the fibrous toner 12 and the rotational speed of the rotary blade 10. Further, the cylindrical cross-sectional diameter D (see FIG. 4) of the cylindrical toner particles 13 depends on the inner diameter of the discharge port of the nozzle 6.
After adding an external additive to the cylindrical toner particles 13 produced by the production method described above, the toner according to the present invention is obtained by mixing with a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.). The external additive is for improving the fluidity of the toner, and the particle diameter thereof is, for example, several tens nm to several hundreds nm.

The standard deviation (SD value) of the particle size distribution of the cylindrical toner particles 13 contained in the toner is preferably 1.20 μm or less.
When the standard deviation of the particle size distribution of the cylindrical toner particles 13 contained in the toner exceeds 1.20 μm, the toner particles become uneven in size, the ratio of excessively charged or poorly charged toner increases, and the charge amount of each toner particle Variation occurs. For this reason, gradation and developability are not good.

The standard deviation of the particle size distribution of the cylindrical toner particles 13 contained in the toner according to the present invention is 1.20 μm or less, which is a relatively sharp particle size distribution. In other words, the toner particles have the same size. Therefore, the charge amount of each toner particle becomes substantially uniform during friction charging. Thereby, good gradation and developability can be realized.
In order to set the standard deviation of the particle size distribution of the cylindrical toner particles 13 to 1.20 μm or less, a cutting process such as stabilizing the conveying speed of the fibrous toner 12 or stabilizing the rotating speed of the rotary blade 10 is performed. What is necessary is just to stabilize the control in.

The cylindrical cross section diameter D of the cylindrical toner particles 13 is, for example, 5.0 μm. In addition, the cylindrical length L of the cylindrical toner particles is preferably 5.0 μm or more and 10.0 μm or less, for example. In other words, the value L / D obtained by dividing the cylinder length by the cylinder cross-sectional diameter is preferably 1.0 or more and 2.0 or less.
When the value L / D obtained by dividing the cylinder length by the cylinder cross-sectional diameter is less than 1.0, the ratio of the cut surface S1 to the entire outer surface of the cylindrical toner particle 13 is high, and the cylindrical toner particle 13 is the cut surface S1. It tends to adhere to the carrier, and the adhesion between the cylindrical toner particles 13 and the magnetic carrier becomes too strong. This makes it difficult for the toner to move toward the image carrier 20. When the value L / D obtained by dividing the cylinder length by the cylinder cross-sectional diameter exceeds 2.0, the ratio of the peripheral surface S2 to the entire outer surface of the cylindrical toner particles 13 is high, and the cylindrical toner particles 13 are in the peripheral surface S2. Therefore, the adhesion between the cylindrical toner particles 13 and the magnetic carrier becomes too strong. This makes it difficult for the toner to move toward the image carrier 20. Thereby, gradation and developability are not good.

In the toner according to the present invention, the value L / D obtained by dividing the cylinder length by the cylinder cross-sectional diameter is 1.0 or more and 2.0 or less, so that the adhesion force between the cylindrical toner particles 13 and the magnetic carrier is appropriately maintained. be able to. For this reason, the toner is favorably moved toward the image carrier 20. Thereby, good gradation and developability can be realized.
In order to set the value L / D obtained by dividing the cylinder length by the cylinder cross-sectional diameter to the above 1.0 or more and 2.0 or less, the diameter of the discharge port of the nozzle 6 is increased / decreased to increase the fibrous toner. The conditions for the cutting process may be set as appropriate, such as adjusting the conveyance speed of 12 or the rotation speed of the rotary blade 10.

Moreover, it is preferable that the average circularity of the cylindrical cross section of the cylindrical toner particles 13 (a surface orthogonal to the center line of the cylinder) is 0.890 or more and 0.920 or less.
If the average circularity of the cylindrical toner particles 13 is less than 0.890, the adhesive force between the cylindrical toner particles 13 and the magnetic carrier becomes too weak, and the toner and the magnetic carrier are easily peeled off, and the toner is removed. The problem of scattering occurs. When the average circularity of the cylindrical toner particles 13 exceeds 0.920, the adhesive force between the cylindrical toner particles 13 and the magnetic carrier becomes too strong, and the toner hardly moves toward the image carrier 20. . On the other hand, if the circularity exceeds 0.920, the toner slips out of the cleaning device 25 and the cleaning performance is deteriorated.

If the average circularity of the cylindrical toner particles 13 is 0.890 or more and 0.920 or less, the adhesive force between the cylindrical toner particles 13 and the magnetic carrier can be maintained appropriately. For this reason, the toner appropriately moves toward the image carrier 20. Thereby, good gradation and developability can be realized.
In order to set the average circularity of the cylindrical toner particles 13 to the above 0.890 or more and 0.920 or less, by increasing / decreasing the diameter of the discharge port of the nozzle 6, What is necessary is just to set the conditions of a cutting process suitably, such as adjusting the rotational speed of the rotary blade 10, etc.

  On the other hand, as the magnetic carrier, for example, magnetic particles such as iron powder and ferrite particles, or a resin carrier in which magnetic particles are dispersed in a resin are used. In addition, the magnetic particles are used as a carrier core for the purpose of controlling the charge amount and polarity of toner, improving humidity dependency, preventing filming (spent phenomenon), and improving fluidity. A so-called resin-coated carrier in which a layer is formed is used. The weight average particle diameter of the magnetic carrier is preferably in the range of 10 μm to 200 μm, particularly in the range of 30 μm to 150 μm.

  The type of binder resin used as the raw material for the toner particles is not particularly limited. For example, polystyrene resin, acrylic resin, styrene-acrylic copolymer, polyethylene resin, polypropylene resin, vinyl chloride It is preferable to use thermoplastic resins such as resins, polyester resins, polyamide resins, polyurethane resins, polyvinyl alcohol resins, vinyl ether resins, N-vinyl resins, and styrene-butadiene resins.

  The polystyrene resin may be not only a homopolymer of styrene but also a copolymer with another copolymerizable monomer copolymerizable with styrene. Examples of copolymerizable monomers that can be copolymerized with styrene include p-chlorostyrene; vinyl naphthalene; ethylene unsaturated monoolefins such as ethylene, propylene, butylene, and isobutylene; halogenations such as vinyl chloride, vinyl bromide, and vinyl fluoride. Vinyl; vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate, vinyl butyrate; methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, dodecyl acrylate, n-octyl acrylate, acrylic (Meth) acrylic acid esters such as 2-chloroethyl acid, phenyl acrylate, methyl α-chloroacrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate; acrylonitrile, methacrylonitrile, acrylamide, etc. Acrylic acid derivatives of: vinyl ethers such as vinyl methyl 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 -N-vinyl compounds such as vinylpyrrolidene. These can be copolymerized with styrene either alone or in combination of two or more.

  The molecular weight of the polystyrene-based resin preferably has two mass average molecular weight peaks (referred to as a low molecular weight peak and a high molecular weight peak) in the binder resin. Specifically, it is preferable that the low molecular weight peak is in the range of 3000 to 20000, the other high molecular weight peak is in the range of 300000 to 1500,000, and the Mw / Mn is 10 or more. When the mass average molecular weight peak is within such a range, the magnetic two-component developer can be easily fixed, and offset resistance can be improved. The mass average molecular weight of the binder resin is determined by measuring the elution time from the column using a molecular weight measuring device (GPC) and comparing it with a calibration curve prepared in advance using a standard polystyrene resin. Can be sought.

  As the polyester resin, those obtained by condensation polymerization or co-condensation polymerization of an alcohol component and a carboxylic acid component are used. The following are mentioned as a component used when synthesize | combining a polyester-type resin. First, dihydric or trihydric or higher alcohol components include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1, Diols such as 4-butenediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol; bisphenol A, hydrogen Bisphenols such as added bisphenol A, polyoxyethylenated bisphenol A, polyoxypropylenated bisphenol A; sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, Entaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, diglycerol, 2-methylpropanetriol, 2-methyl-1,2,4- Examples include trivalent or higher alcohols such as butanetriol, trimethylolethane, trimethylolpropane, 1,3,5, -trihydroxymethylbenzene.

  Furthermore, as the divalent or trivalent or higher carboxylic acid component, a divalent or trivalent carboxylic acid, an acid anhydride thereof or a lower alkyl ester thereof is used. 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, Divalent carboxylic acids such as alkyl or alkenyl succinic acid such as n-octyl succinic acid, n-octenyl succinic acid, n-dodecyl succinic acid, n-dodecenyl succinic acid, isododecyl succinic acid and isododecenyl succinic acid; , 4-Benzenetricarboxylic acid (trimellitic acid), 1,2, Benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-di Carboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, empor trimer Examples thereof include trivalent or higher carboxylic acids such as acids.

The softening point of the polyester resin is preferably 110 ° C to 150 ° C, more preferably 1.20 µm ° C to 140 ° C.
The binder resin is preferably a thermoplastic resin from the viewpoint of good fixability, but the amount of cross-linked portion (gel amount) measured using a Soxhlet extractor is a value of 10% by mass or less, more preferably 0.8. If it is a value within the range of 1% by mass to 10% by mass, a thermosetting resin may be used. 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 it is also preferable to add a cross-linking agent or to partially use a thermosetting resin.

  Therefore, an epoxy resin, a cyanate resin, or the like can be used as the thermosetting resin. 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.

  In such a binder resin, in order to improve the dispersibility of the magnetic powder, at least one functional group selected from a hydroxyloxy (hydroxy acid) group, a carboxyl group, an amino group, and a glycidoxy (epoxy) group is used as a molecule. It is preferable to use the resin contained therein. In addition, it can be confirmed using an FT-IR apparatus whether it has these functional groups, and also can be quantified using a titration method.

  Furthermore, in the binder resin, the glass transition point (Tg) is preferably set to a value within the range of 50 ° C to 70 ° C. When the glass transition point of the binder resin is less than 50 ° C., the obtained toners are fused with each other, and the storage stability tends to be lowered. On the other hand, when the glass transition point of the binder resin exceeds 70 ° C., the fixability of the toner tends to be poor. In addition, the glass transition point of binder resin can be calculated | required from the change point of specific heat using a differential scanning calorimeter (DSC).

  The wax as a release agent 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; And Fischer-Tropsch (hereinafter sometimes referred to as “FT”) wax, synthetic wax such as polyethylene wax and polypropylene wax. Among these, from the viewpoint of dispersibility, use of FT wax or polyethylene wax having ester in the side chain is recommended.

The wax as the release agent preferably has an endothermic main peak in a range of 70 to 120 ° C. in an endothermic curve obtained by a differential scanning calorimeter. This is because when the endothermic main peak is less than 70 ° C., toner blocking and hot offset may occur, and when the endothermic main peak exceeds 120 ° C., low temperature fixability may not be obtained.
Furthermore, the addition amount of the wax as a release agent is preferably in the range of 1 to 20 parts by weight with respect to 100 parts by weight of the binder resin. If the addition amount of the wax is less than 1 part by weight, it is difficult to obtain a sufficient effect of the wax. On the other hand, if the addition amount is more than 20 parts by weight, the blocking resistance is lowered and the toner may be detached.

  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, Tartrazine Lake; orange pigment, reddish yellow lead, molybten orange, permanent orange GTR , 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. Such a colorant is preferably used in an amount of 2 to 20 parts by weight, particularly 3 to 15 parts by weight, per 100 parts by weight of the binder resin.

  The type of the charge control agent is not particularly limited. For example, nigrosine, a quaternary ammonium salt compound, a resin type charge control agent in which an amine compound is bonded to a resin, and the like exhibit positive chargeability. Charge control agents can be used. When used for a color toner, a colorless or white one is preferable. It is preferably used in an amount of 0.5 to 10 parts by weight, particularly 1 to 5 parts by weight per 100 parts by weight of the binder resin.

As the external additive, conventionally known external additives such as silica, alumina, tin oxide, titanium oxide, strontium oxide, and various resin powders can be used.
On the other hand, in the case of magnetic carriers, as the carrier core material, particles of iron, oxidized iron, reduced iron, magnetite, copper, silicon steel, ferrite, nickel, cobalt, etc., and alloys of these materials with manganese, zinc, aluminum, etc. Particles, iron-nickel alloy, iron-cobalt alloy particles, 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 and lithium niobate, particles of high dielectric constant materials such as ammonium dihydrogen phosphate, potassium dihydrogen phosphate, and Rochelle salt, resin in which the above magnetic particles are dispersed in resin Various conventionally known ones such as carriers are used.

  As resin coating layer of magnetic carrier, (meth) acrylic polymer, styrene polymer, styrene- (meth) acrylic copolymer, olefin polymer (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, fluorine resin (polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, etc.), Various conventionally known resins can be used for coating carriers such as phenol resin, xylene resin, diallyl phthalate resin, polyacetal resin, and amino resin. These may be used alone or in admixture of two or more.

The resin coating layer contains 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, etc. It can also be made.
The film thickness of the resin coat layer may be the same as that of the prior art, and is not particularly limited. Specifically, the resin coat layer is expressed as a coating amount on the carrier core material and is 0.01 to 10% by weight with respect to the carrier core material. The coating amount is preferably 0.05 to 5% by weight.

  Other additives such as a surface treatment agent can be added to the magnetic two-component developer as long as the effects of the present invention are not impaired.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples.
(Preparation of magnetic two-component developer)
Carnauba wax (manufactured by Toa Kasei Co., Ltd.) as a release agent and charge control agent (P-51: manufactured by Orient Chemical Industry Co., Ltd.) 3 with respect to 100 parts by weight of a binder resin made of styrene-acrylic resin 2 parts by weight and carbon black as a colorant (MA-100: manufactured by Mitsubishi Chemical Corp.): 5 parts by weight, using the apparatus shown in FIG. 2 and FIG. A cylindrical toner particle having a volume average particle diameter of 6.5 μm was prepared, and 1.8 parts by mass of hydrophobic silica (RA-200H: manufactured by Nippon Aerosil Co., Ltd.) as an external additive was added to the cylindrical toner particle. Toner was obtained by adding 1.0 part by mass of titanium oxide having a diameter of 250 nm (ST-100, manufactured by Titanium Industry Co., Ltd.) and stirring and mixing with a Henschel mixer at a rotational peripheral speed of 40 m / s for 5 minutes. This toner and a ferrite carrier (Powder Tech Co., Ltd.) are blended so that the ratio of the toner and the magnetic carrier is 1:10, and stirred and mixed for 30 minutes using a rocking mixer to produce a magnetic two-component developer. Got.

Example 1: As the above-described magnetic two-component developer, a value L / D obtained by dividing the column length of columnar toner particles by the column cross-sectional diameter is 1.5, and the average circularity of the columnar toner particles is 0.00. 897, and a toner containing toner having a standard deviation of the particle size distribution of cylindrical toner particles of 1.167 μm was used.
Example 2: As the above-described magnetic two-component developer, a value L / D obtained by dividing the column length of the cylindrical toner particles by the cylindrical cross-sectional diameter is 1.6, and the average circularity of the cylindrical toner particles is 0.00. 909, and a toner containing toner having a standard deviation of the particle size distribution of cylindrical toner particles of 1.161 μm was used.

Example 3 As the above-mentioned magnetic two-component developer, a value L / D obtained by dividing the column length of the cylindrical toner particles by the diameter of the column cross section is 1.2, and the average circularity of the cylindrical toner particles is 0. A toner containing 938 and a toner having a standard deviation of the particle size distribution of cylindrical toner particles of 1.186 μm was used.
Example 4 As the above-described magnetic two-component developer, the value L / D obtained by dividing the column length of the cylindrical toner particles by the column cross-sectional diameter is 1.5, and the average circularity of the cylindrical toner particles is 0.00. A toner containing toner having a standard deviation of the particle size distribution of cylindrical toner particles of 1.899 μm was used.

Example 5: As the above-described magnetic two-component developer, the value L / D obtained by dividing the column length of the cylindrical toner particles by the cylindrical cross-sectional diameter is 2.1, and the average circularity of the cylindrical toner particles is 0.00. 881 and a toner containing toner having a standard deviation of the particle size distribution of cylindrical toner particles of 1.189 μm were used.
Comparative Example 1: As the above-described magnetic two-component developer, a value L / D obtained by dividing the column length of the cylindrical toner particles by the cylindrical cross-sectional diameter is 2.1, and the average circularity of the cylindrical toner particles is 0.00. 887, and a toner containing toner having a standard deviation of the particle size distribution of cylindrical toner particles of 1.212 μm was used.

  Comparative Example 2: Carbana wax (manufactured by Toa Kasei Co., Ltd.) as a release agent and charge control agent (P-51: Orient Chemical Industries (100 parts by weight) with respect to 100 parts by weight of a binder resin made of styrene-acrylic resin Co., Ltd.) 3 parts by weight and carbon black as a colorant (MA-100: manufactured by Mitsubishi Chemical Co., Ltd.): 5 parts by weight are used as a toner raw material in a melt-kneading step, a coarse grinding step, a fine grinding step, and a classification. Toner particles having a volume average particle diameter of 6.5 μm are prepared by a pulverization method including a process, and hydrophobic silica (RA-200H: manufactured by Nippon Aerosil Co., Ltd.) as an external additive is added to the pulverized toner particles. 8 parts by mass, 1.0 part by mass of titanium oxide having a particle size of 250 nm (ST-100, manufactured by Titanium Industry Co., Ltd.) is added, and the toner is stirred and mixed with a Henschel mixer at a rotational peripheral speed of 40 m / s for 5 minutes. Obtained. This toner and a ferrite carrier (Powder Tech Co., Ltd.) are blended so that the ratio of the toner and the magnetic carrier is 1:10, and stirred and mixed for 30 minutes using a rocking mixer to produce a magnetic two-component developer. Got.

A value L / D obtained by dividing the major axis (here, L) of the toner particles obtained by the above pulverization method by the minor axis (here, D) is 1.0, and the average circularity of the toner particles is 0.00. A magnetic two-component developer having a toner particle size distribution of 939 and a standard deviation of the toner particle size distribution of 1.235 μm was used.
Comparative Example 3: As a magnetic two-component developer produced by the same raw material and production method as in Comparative Example 2, the value L / D obtained by dividing the major axis of the toner particles by the minor axis is 1.0, and the average circularity of the toner particles And a toner containing toner with a standard deviation of the particle size distribution of toner particles of 1.245 μm was used.

Comparative Example 4: As a magnetic two-component developer produced by the same raw materials and production method as in Comparative Example 2, the value L / D obtained by dividing the major axis of the toner particles by the minor axis is 1.0, and the average circularity of the toner particles And a toner containing toner with a standard deviation of the particle size distribution of toner particles of 1.264 μm was used.
Comparative Example 5: As the above-described magnetic two-component developer, the value L / D obtained by dividing the column length of the cylindrical toner particles by the diameter of the column cross section is 1.5, and the average circularity of the cylindrical toner particles is 0.00. 935 and a toner containing a toner (produced by the above-mentioned melt blown method) having a standard deviation of the particle size distribution of the cylindrical toner particles of 1.27 μm was used.

(Measuring method)
The standard deviation (SD value) of the particle size distribution of the toner particles was measured using a Coulter Counter Multisizer 3 (manufactured by Beckman Coulter, Inc.). Specifically, 10 mg of a measurement sample is added to a solution obtained by adding a small amount of a surfactant to the electrolytic solution, and a dispersion treatment is performed by an ultrasonic disperser, and the solution in which the measurement sample is dispersed is measured by the measurement device, A volume distribution of sample particle size was obtained. Isoton II (manufactured by Beckman Coulter, Inc.) was used as the electrolyte, and a 100 μm aperture was used as the aperture.

  The standard deviation (SD value) is a standard deviation based on the volume average particle diameter, and is represented by the following formula.

は、体積平均粒径を示す。
円柱トナー粒子の円柱長さを円柱断面直径で除した値Ｌ／Ｄは、以下のようにして求める。すなわち、電子走査顕微鏡によりトナーの２０００倍像を撮像し、このときの画像に写り込んだ円柱状トナー粒子を１００個ランダムに抽出し、各円柱状トナー粒子の円柱長さＬおよび円柱断面直径Ｄについて平均値を求め、その平均値に基づき、各トナーにおける円柱状トナー粒子の円柱長さを円柱断面直径で除した値Ｌ／Ｄが算出される。切断面が円柱状トナーの中心軸に対して直交していない場合（切断面が傾斜あるいは湾曲している場合）、その中心軸の軸線長さを円柱長さＬとする。なお、比較例２〜４については、上記の円柱トナー粒子の測定法に準じた測定方法により、トナー粒子の長径（ここではＬとする）を短径（ここではＤとする）で除した値Ｌ／Ｄが求められる。 In Equation 2, n is the number of measured toners, X _i (i = 1, 2, 3,...
n) represents the particle diameter of the toner. Also,

Indicates a volume average particle size.
A value L / D obtained by dividing the cylindrical length of the cylindrical toner particles by the cylindrical cross-sectional diameter is obtained as follows. That is, a 2000 times image of the toner is taken with an electronic scanning microscope, 100 cylindrical toner particles appearing in the image at this time are randomly extracted, and the cylindrical length L and the cylindrical cross-sectional diameter D of each cylindrical toner particle are extracted. An average value is obtained for, and based on the average value, a value L / D is calculated by dividing the cylindrical length of the cylindrical toner particles in each toner by the cylindrical cross-sectional diameter. When the cut surface is not orthogonal to the central axis of the cylindrical toner (when the cut surface is inclined or curved), the axial length of the central axis is defined as the cylinder length L. In Comparative Examples 2 to 4, a value obtained by dividing the major axis (here, L) of the toner particles by the minor axis (here, D) by a measuring method according to the measuring method of the cylindrical toner particles described above. L / D is required.

The average circularity is measured using a flow type particle image analyzer (FPIA-2100 manufactured by Sysmex Corporation) in an environment of 23 ° C. and 60% RH, and the circularity (a) of the measured particles is shown below. A value obtained by dividing the total roundness of all the particles measured by the number of particles is defined as the average roundness.
a = L ₀ / L (3)
(L ₀ : Peripheral length of a circle having the same projected area as the projected image of the particle, L: Image processing of the projected image of the particle with an image processing resolution of 512 × 512 (pixels of 0.3 μm × 0.3 μm) When perimeter)
(Performance evaluation)
Among the 10 types of magnetic two-component developers described above, the magnetic two-component developers of Examples 1 to 5 and Comparative Examples 1 to 5 are copied from a copying machine (laser manufactured by Kyocera Mita Co., Ltd.) that employs the two-component development method. Using a printer “KM-4055” modified), an image is formed based on a document having a document density of 4% in a normal temperature and humidity environment of a temperature of 20 ° C. and a humidity of 60%, and the following performance evaluation is performed. went.
(I) Gradation In order to confirm whether or not the present invention has the effect of improving gradation, gradation evaluation was performed. The copied image was visually observed to evaluate the gradation.
A: Gradation was very good.
○: Gradation was normal.
(Triangle | delta): The gradation property was bad.
X: The gradation was extremely bad.
(Ii) Image Density In order to confirm the presence or absence of the effect of improving developability according to the present invention, image density evaluation was performed. The image density at the three black solid portions of one copy image is measured using a reflection densitometer (TC-6D manufactured by Tokyo Denshoku Co., Ltd.), and the average value of the measured image density is the image of the formed image. Concentration. As a criterion for evaluation, the image density is required to be 1.30 or more, and more preferably 1.40 or more.

These performance evaluations are performed at the timing after continuous printing of 10,000 sheets in the image forming process. Here, continuous printing is printing that continuously performs image formation.
The performance evaluation results are shown in Table 1.

From the test results shown in Table 1, Examples 1, 2, 3, and 5 in which the standard deviation (SD value) of the particle size distribution of the cylindrical toner particles produced by the melt blown method is 1.20 μm or less are the cylindrical toners. Compared with Comparative Example 1 and Comparative Example 5 in which the standard deviation of the particle size distribution of the particles is not within the above range, it was found that the gradation and developability were good.
Examples 1-4 in which the value L / D obtained by dividing the cylindrical length of the cylindrical toner particles by the cylindrical cross-sectional diameter is in the range of 1.0 to 2.0 are the particle size distribution of the cylindrical toner particles. Compared with Comparative Example 1 and Comparative Example 5 in which the standard deviation was not within the above range, it was found that the gradation and developability were good.

Further, Examples 1, 2, and 4 in which the average circularity of the cylindrical toner particles is in the range of 0.890 to 0.920 are compared with Comparative Example 1 and Comparative Example 1 in which the average circularity of the cylindrical toner particles is not in the above range. Compared to Example 5, it was found that the gradation and developability were good.
Examples 1 to 5 including columnar toner particles prepared by the melt blown method have better gradation and developability than Comparative Examples 2 to 4 including columnar toner prepared by the powder method. I found out.

  Furthermore, the standard deviation (SD value) of the particle size distribution of the cylindrical toner particles is 1.20 μm or less, and the value L / D obtained by dividing the column length of the cylindrical toner particles by the column cross-sectional diameter is 1.0 or more. Examples 1 and 2 in which the average circularity of the cylindrical toner particles is in the range of 0.890 to 0.920 are in the range of 2.0 or less, and the average circularity is out of the above range. Compared with Example 4 in which the standard deviation of the particle size distribution deviates from the above range, and in Example 5 in which the value L / D obtained by dividing the cylinder length by the cylinder cross-sectional diameter and the average circularity deviates from the above range, It was found that tonality and developability were even better.

FIG. 2 is a schematic diagram illustrating a configuration of an image forming mechanism in which image formation is performed using a magnetic two-component developer including a magnetic two-component developer toner according to an embodiment of the present invention. It is a figure for demonstrating a kneading | mixing process and a fiberization process among the manufacturing methods of a cylindrical toner particle. It is a figure for demonstrating a cutting process among the manufacturing methods of a cylindrical toner particle. It is the schematic for demonstrating a cylindrical toner particle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image formation mechanism 13 Cylindrical toner particle 23 Developer carrier D Cylindrical cross-sectional diameter L of cylindrical toner particle Cylindrical length of cylindrical toner particle

Claims (3)

It is obtained by externally adding fine particles to cylindrical toner particles produced by stretching and cutting a toner component in a molten state into a cylindrical fiber shape,
A toner for magnetic two-component developer, wherein the standard deviation of the particle size distribution of the cylindrical toner particles is 1.20 μm or less. It is obtained by externally adding fine particles to cylindrical toner particles produced by stretching and cutting a toner component in a molten state into a cylindrical fiber shape,
A toner for magnetic two-component developer, wherein a value obtained by dividing the column length of the columnar toner particles by the column cross-sectional diameter is 1.0 or more and 2.0 or less. It is obtained by externally adding fine particles to cylindrical toner particles produced by stretching and cutting a toner component in a molten state into a cylindrical fiber shape,
The toner for magnetic two-component developer, wherein the cylindrical toner particles have an average circularity of 0.890 or more and 0.920 or less.

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