JP6690361B2 - Replenishing carrier, replenishing two-component developer and image forming method in auto-refining development system - Google Patents

Description

  The present invention relates to a replenishing carrier, a replenishing two-component developer, and an image forming method in an auto refining developing system.

  2. Description of the Related Art In recent years, electrophotographic copying machines and printers have been increasingly used not only in conventional office applications but also in production printing fields due to higher printing speeds.

  In the production printing field, a large amount of printing is performed at high speed, and therefore a developer that does not deteriorate the image quality even when a large amount of continuous printing is performed is required. In order to reduce the deterioration of image quality, a method of suppressing toner adhesion to the carrier can be considered. Although many methods for suppressing toner adhesion to the carrier have been proposed, they eventually reach the end of their life and require replacement of the developer.

  In order to reduce the number of times this developer is exchanged as much as possible, an image forming method that employs a so-called auto-refining development method in which excess developer is gradually discharged and the discharged toner and carrier are replenished It has been proposed (see, for example, Patent Documents 1 to 3).

  In this auto-refining development method, the excess developer is gradually discharged from the developing device, and the carrier according to the amount of the discharged developer and the discharged developer in addition to the amount consumed by the image formation are discharged. The amount of toner contained in the agent is replenished. By adopting such an auto-refining development method, the deteriorated developer is gradually replaced with a new one, so that the excessive deterioration of the developer is suppressed and, as a result, the deterioration of the image quality is caused for a long period of time. Will be reduced.

  On the other hand, as described above, high image quality is required in the production printing field, and one of them is the white spot on the lead portion (when a solid image is printed after halftone, the leading edge image on the solid portion is white spot). Phenomenon). It is effective to reduce the resistance value of the carrier (initial carrier) in order to deal with the blank portion of the lead portion.

  Patent Document 4 describes replenishing a carrier having a resistance value higher than the electric resistance value of the initial carrier housed in the developing device. However, the quality required for production printing in recent years is described. On the other hand, it is not satisfactory, for example, there is a problem in terms of image quality, a large number of carriers adhere to the surface of the photoconductor, and toner scattering causes stains on the inside of the printing machine.

JP, 2001-330985, A JP, 2004-287269, A JP, 2007-079578, A JP-A-3-145678

  Therefore, what the present invention intends to solve is to reduce the deterioration of image quality even when a printing machine is used for a long period of time, and to suppress many carriers from adhering to the surface of the photoconductor. Another object of the present invention is to provide a technique capable of suppressing stains inside the printing machine due to toner scattering.

  The present inventors have conducted earnest research to solve the above problems. As a result, in the developing process in which the electrostatic latent image formed on the electrostatic latent image carrier is visualized by the two-component developer containing toner and carrier, the surplus two-component developer is discharged from the developing device. In addition, the replenishment toner and the replenishment carrier are replenishment carriers in the developing device in which the replenishment toner and the replenishment carrier are replenished into the developing device, and have the following relationship with the initial carrier contained in the developing device. :

It was found that the above problems can be solved by providing the above, and the present invention has been completed.

  According to the present invention, even when the printing machine is used for a long period of time, deterioration of image quality is reduced, and a large number of carriers are prevented from adhering to the surface of the photoconductor. It is possible to provide a technique capable of suppressing dirt inside the aircraft.

FIG. 3 is a perspective view showing a developer accommodating container used in an example of the present invention. FIG. 2A is a schematic diagram showing an example of a toner image in which the solid portion BT and the halftone portion HT are adjacent to each other in the sub-scanning direction, and FIG. 2B is a diagram showing the development area GR and the photosensitive drum 31Y. FIG. 6 is a schematic diagram showing a developing method (normal development) in which development is performed while the roller 46Y moves in the same direction.

  Hereinafter, preferred embodiments of the present invention will be described in detail. Further, in the present specification, “X to Y” indicating a range means “X or more and Y or less”. Unless otherwise specified, operations and measurements of physical properties are performed under the conditions of room temperature (20 to 25 ° C.) / Relative humidity 40 to 50% RH.

  According to the present invention, in a developing process in which an electrostatic latent image formed on an electrostatic latent image carrier is visualized by a two-component developer containing a toner and a carrier, surplus two-component developer is discharged from a developing device. In addition, the replenishing toner and the replenishing carrier are replenishing carriers in the developing device, which are replenishing carriers in the auto-refining development system, and have the following relationship with the initial carrier contained in the developing device. Be a carrier.

  By having such a configuration, deterioration of image quality is reduced even when a printing machine is used for a long period of time, a large number of carriers are prevented from adhering to the surface of the photoconductor, and printing due to toner scattering is performed. It is possible to suppress dirt inside the machine.

If the resistance value (X) of the initial carrier in the above formula 1 is less than 5.00 × 10 ⁸ (Ω · cm), fog, toner scattering, reduction in transfer rate, and carrier adhesion may occur. If the resistance value (X) of the initial carrier is more than 1.00 × 10 ¹⁰ (Ω · cm) in the above formula 1, the white spot performance of the lead portion may be deteriorated. Further, in the present invention, by controlling the resistance value (Y) of the replenishing carrier so as to fall within the range of the above formula 2, white spots on the lead portion, fog and toner scattering, and lowering of transfer rate are suppressed, and carrier adhesion performance is suppressed. Can be maintained at a high level for a long time (through endurance).

  As described above, the present invention solves the intended problem by making the resistance values of the initial carrier and the replenishment carrier constant, but the parameters defined in the formula 1 and the formula 2 have many combinations. It is derived from the experimental result of.

  Explaining the meanings of Expression 1 and Expression 2 in plain terms, first, the initial carrier is designed so that the resistance value (X) of the initial carrier defined by Expression 1 becomes a predetermined value. Then, by setting the mass (A) of the initial carrier already in the developing unit and the ratio (B) of the replenishing carrier in the replenished two-component developer, the values on the left side and the right side are calculated, and The carrier (Y) for replenishment is designed so that the resistance value falls within the range. Here, the mass (A) of the initial carrier has a substantially constant value throughout the durability, and the fluctuation level thereof is negligible.

  Next, how Equation 2 is derived will be described.

Formula 2 evaluates many combinations of the initial carrier resistance value (X), the mass of the initial carrier (A), and the ratio (B) of the replenishment toner and the replenishment carrier to the replenishment carrier, and the desired result is obtained. It was derived by conducting an experiment in which the resistance value (Y) of the replenishing carrier that achieved the above purpose was changed. More specifically, the horizontal axis is (B) and the vertical axis is (Y / X), and a plurality of plots are obtained for each mass (A) of the initial carrier, and power approximation is performed for each mass (A) of the initial carrier. It created the formula ^{(Y / X = αB β)} . As a result, a plurality of power approximation formulas can be obtained, so that the respective coefficients were calculated for α and β. The value calculated from the lower limit and the upper limit is Equation 2 of the present invention.

  Here, in general, in order to suppress image quality deterioration, transfer rate deterioration, or carrier adhesion due to carrier deterioration, it is necessary to increase the carrier supply amount and increase the exchange ratio. However, if the supply amount of the carrier is increased, the discarded carrier will increase. In particular, in the method in which the carrier and the toner are mixed in advance and replenished as a developer, when a document having a high blackened area ratio is copied, the toner consumption is large, and thus it is necessary to increase the toner replenishment amount. As a result, the amount of replenishment of the carrier also increases at the same time, which causes a problem that the waste loss of the developer increases. According to the present invention, the replenishment amount of the replenishment carrier can be made appropriate, so that such a problem can be solved.

  In the present specification, the relationship of at least one of Expression 1 and Expression 2 may be referred to as a “specific relationship”.

  In the present invention, by making the resistance value of the replenishing carrier and the resistance value of the initial carrier have the above-described specific relationship, even when the printing machine is used not only at the initial stage but also for a long period of time ( The carrier resistance value in the developing device can be kept constant (through durability). In other words, a high image quality is achieved by significantly lowering the resistance value of the initial carrier, and a decrease in toner charge amount, a decrease in image quality such as fogging, and a decrease in transfer rate are suppressed by controlling the resistance value so that it does not fall to dark clouds. be able to. In other words, in the present invention, the resistance value of the initial carrier is relatively decreased, but the reduction width is made constant and the resistance value in the developing device is stabilized through the replenishment carrier, so that high image quality can be maintained for a long time. We will maintain it for a long time and solve the intended problem. As described above, the present invention is characterized in that the resistance value between the resistance at the start of use (initial resistance) and the carrier value supplied from the toner bottle as the auto-refining carrier is intentionally designed.

  In particular, it is necessary to increase the amount of carrier contained in the developing device in order to continuously print images with a high printing rate required for production printing. It becomes difficult to control the carrier resistance value. Further, from the viewpoint of resource saving, it is required to reduce the amount of replenished carrier, but the replacement of the carrier becomes slow, and it becomes difficult to control the carrier resistance value through durability. On the other hand, in the present invention, since the resistance value of the replenishing carrier and the resistance value of the initial carrier have the above-described specific relationship, such a problem can be solved.

In the above formula 1, the initial carrier resistance value (X) is 5.00 × 10 ⁸ (Ω · cm) or more, but from the viewpoint of carrier adhesion, preferably 1.00 × 10 ⁹ (Ω · cm) or more. And more preferably 2.00 × 10 ⁹ (Ω · cm) or more.

In the above formula 1, the initial carrier resistance value (X) is 1.00 × 10 ¹⁰ (Ω · cm) or less, but it is preferably 5.00 × 10 ⁹ (Ω · cm) from the viewpoint of white spots in the lead portion. ) Or less, and more preferably 3.00 × 10 ⁹ (Ω · cm) or less.

  Further, in the above formula 2, the mass (A) of the initial carrier is preferably 470 g or more, more preferably 500 to 800 g, and further preferably from the viewpoint of ensuring image quality when images having a high printing rate are continuously formed. It is 570 to 800 g. Such a form will be described later.

  Further, in the above formula 2, the ratio B (mass%) of the replenishment toner and the replenishment carrier in the replenishment carrier is preferably 3 to 25 mass%, more preferably from the viewpoint of achieving the intended effect of the present invention. Is 4 to 15% by mass, more preferably 5 to 12% by mass.

(Supply carrier)
Next, the replenishment carrier of the present invention will be described.

  The replenishment carrier of the present invention is a replenishment type development that is replenished independently and separately from the replenishment toner as long as it is replenished in the auto-refining development system so as to satisfy the formula 1 and the formula 2 with the initial carrier. It may be supplied to a process or may be supplied to a replenishment type development process in which it is mixed with a replenishment toner and replenished as a replenishment two-component developer.

  The replenishing carrier of the present invention may be composed of a magnetic material, or may be a resin-coated carrier in which a coating resin is applied to the surface of a carrier core material containing a magnetic material, or The carrier may be a resin dispersion type carrier in which fine magnetic powder is dispersed, but from the viewpoint of suppressing carrier adhesion to the photoreceptor, a coating resin is applied to the surface of the carrier core material containing the magnetic material. It is preferable that the resin-coated carrier is That is, according to a preferred embodiment of the present invention, the replenishment carrier is configured to include a carrier core material and a coating resin that coats the surface of the carrier core material. Of course, the initial carrier, which will be described later, may also be configured to include a carrier core material and a coating resin that coats the surface of the carrier core material.

(Carrier core material)
The shape of the carrier core material constituting the replenishment carrier of the present invention is not particularly limited, and may be, for example, a particulate shape. Further, this carrier core material may contain an internal additive such as a resistance adjusting agent, if necessary. Here, examples of the resistance adjusting agent include carbon black, titanium oxide, ITO, tin oxide, and the like, and those described in paragraph “0039” of JP2004-287196A and JP2014-48455A. And the like described in the paragraph “0046” of may be used.

The magnetic substance forming the carrier core material is a substance that is strongly magnetized in that direction by a magnetic field, for example, iron, ferrite represented by the formula (a): MO · Fe ₂ O ₃ , and formula (b): MFe ₂ O ₄ Iron, including magnetite represented by, metal exhibiting ferromagnetism such as nickel and cobalt, or alloy or compound containing these metals, alloy containing no ferromagnet but exhibiting ferromagnetism by heat treatment (for example, Heusler alloys such as manganese-copper-aluminum and manganese-copper-tin, chromium dioxide, etc.) and the like.

  In the above formulas (a) and (b), M is a monovalent or divalent metal such as Mn, Fe, Ni, Co, Cu, Mg, Zn, Cd, Li and Sr, and these are singly. Alternatively, two or more kinds can be used in combination.

Further, as the carrier core material, since it has a smaller specific gravity than metals such as iron and nickel and can be reduced in weight, it is possible to reduce the impact force of stirring in the developing device, and thus various ferrites are used. preferable. Here, the saturation magnetization is in the range of 30~75Am ² / kg, it is preferable residual magnetization is not more than 5.0Am ² / kg. By setting the preferable range of the saturation magnetization as shown on the left, the holding force between the developing sleeve and the carrier in the developing device can be increased, and the carrier adhesion due to the centrifugal force can be suppressed. Further, it is possible to easily replace the carrier (developer) from the developing sleeve, and it is possible to suppress the occurrence of an image defect called a ghost in which the same developer is repeatedly used in the developing process.

  By using the carrier having such magnetic characteristics, the carrier is prevented from partially aggregating, and the two-component developer is uniformly dispersed on the surface of the developer transport member, so that the density is uniform and uniform. It becomes possible to form a high-definition toner image. The saturation magnetization of the carrier core material is measured by a DC magnetization characteristic automatic recording device "3257-35" (manufactured by Yokogawa Electric Corporation).

The resistance value of the carrier core material is preferably in the range of 5.0 × 10 ⁶ (Ω · cm) to 1.0 × 10 ⁹ (Ω · cm). A more preferable range is 1.0 × 10 ⁷ (Ω · cm) to 5.0 × 10 ⁸ (Ω · cm). When the resistance value is in this range, it is possible to suppress fogging, toner scattering, and decrease in transfer rate, and it is possible to suppress carrier adhesion and white spots on the lead portion.

Ferrite may be produced by appropriately referring to a known method. For example, the methods described below can be mentioned. Fe ₂ O ₃ and _{Mn (OH) 2, Mg (} OH) 2 or MnO, _MgO, ferrite raw materials such as _Fe 2 O 3, SrO, mixed with optionally dispersing medium (e.g. water). At this time, a pulverized product (slurry) is obtained by pulverizing and mixing using a media mill, a ball mill, a vibration mill or the like. The mixing time at this time is preferably 0.5 hours or more, more preferably 4 to 30 hours. If necessary, the obtained slurry is dried by a known drying means (for example, spray drying). At this time, the shape is preferably spherical (preferably spherical). Then, the particle size is adjusted as needed. After that, calcination is performed. As the calcination device used for the calcination, for example, a known calcination device such as an electric furnace or a rotary kiln can be used. The calcination is performed once to three times as needed. The calcination temperature is preferably 800 to 1100 ° C, more preferably 900 to 1050 ° C. The calcination time is preferably 1 to 15 hours, more preferably 2 to 10 hours. The calcination has a technical effect of converting the raw material into an oxide.

  Thereafter, if necessary, the calcined product is pulverized by a dry method or a wet method, and in some cases, a dispersion medium (for example, water) or a binder such as a cellulose resin is used to make the pulverized product into a slurry, and a known pulverization means ( For example, pulverization is performed by a wet ball mill etc. until the volume average particle diameter (D50) reaches a desired particle diameter. At this time, a grinding aid (eg, stainless beads, zirconia beads, etc.) may be used. At this time, in order to control to a desired D50, the crushing time is preferably 1 to 40 hours, more preferably 1.5 to 35 hours.

  Then, it is granulated and dried using a known drying means (spray dryer or the like). At that time, a known binder (for example, PVA or the like) may be used.

  Next, the granulated product is subjected to main firing. The main calcination may be performed while controlling the oxygen concentration. As a firing device to be used, a known firing device such as an electric furnace or a rotary kiln can be used.

  The volume average particle diameter of the carrier core material is preferably 20 to 100 μm, and more preferably 25 to 80 μm. The volume average particle diameter of the carrier core material can be measured according to the method described in the examples.

  The present invention is characterized in that the replenishment carrier has a specific relationship. The method of controlling so as to have such a specific relationship is not particularly limited, but one of the methods is to adjust the temperature of the main calcination. When the temperature of the main calcination is increased, the distance between the crystal grains constituting the carrier core material is shortened and the volume resistance is lowered. Further, if the temperature of the main calcination is increased, the carrier shape factor SF-1 can be increased, that is, the carrier can be made to have a different shape. When the carrier core material is deformed to a greater extent and is coated with a coating resin, the more the deformed shape is, the more the convex portion having the smaller coating amount is present, and the lower the resistance can be.

  In the carrier for replenishment, the carrier shape factor SF-1 of the carrier core material is preferably 110 to 150, and particularly preferably 130 to 145.

  In the initial carrier described later, the carrier shape factor SF-1 of the carrier core material is preferably 110 to 150, and particularly preferably 130 to 145.

  The temperature of the main calcination for the replenishing carrier is preferably 800 to 1400 ° C, and more preferably 900 to 1300 ° C. Further, the time of the main firing is preferably 0.5 to 40 hours, more preferably 1 to 30 hours, and further preferably 3 to 10 hours.

  On the other hand, for the initial carrier described below, the main calcination temperature is preferably 800 to 1400 ° C, and more preferably 900 to 1300 ° C. The time for the main calcination is preferably 0.5 to 40 hours, more preferably 1 to 30 hours, and further preferably 3 to 10 hours.

  The fired product thus obtained is pulverized (crushed) and classified, if necessary. As the classification method, there are existing wind classification, mesh filtration method, sedimentation method and the like. In that way, the particle size is adjusted to the desired particle size.

(Shape factor SF-1 measuring method)
The shape factor (SF-1) of the carrier core material is a numerical value calculated by the following formula A.

  In the measurement of SF-1 of the carrier core material, the carrier core material is usually prepared. However, when the sample (object to be measured) is not the carrier core material alone but the two-component developer (toner and carrier), the preparation process is performed.

(Preparation)
To the beaker, add the two-component developer (carrier and toner), a small amount of neutral detergent, and deionized water, and blend well, and discard the supernatant while applying a magnet to the bottom of the beaker. Further, pure water is added and the supernatant liquid is discarded to remove the toner and the neutral detergent, thereby separating only the carrier. Dry at 40 ° C. to obtain a carrier alone.

  When the surface of the carrier core material is coated with resin, the shape factor of the carrier core material can be measured by removing the resin covering the surface. The removal method is not particularly limited, but for example, the resin-coated carrier core material is placed in a beaker, an organic solvent capable of dissolving the resin (eg, methyl ethyl ketone, acetone, THF) is added, and the time is about 20 minutes. After stirring, the organic solvent is discarded. Further, an organic solvent is added, the same operation is repeated three times, and then the carrier core particles can be obtained by drying at a temperature at which the residual organic solvent can be removed for about 24 hours. Alternatively, carrier core particles can be obtained by putting a resin-coated carrier core material in a crucible and raising the temperature to a temperature at which the resin and additives can be thermally decomposed.

(Measurement)
A scanning electron microscope randomly photographs 100 or more carrier core particles at a magnification of 150, and a photographic image captured by a scanner is used as an image processing analyzer LUZEX (registered trademark) AP (Nireco Corporation). Is used to calculate the maximum length and the projected area of each carrier core material particle, and the shape factor SF-1 is calculated by the above equation (A). The calculated average value of the shape factor SF-1 of each particle is referred to as "shape factor SF-1" in the present invention.

(Coating resin)
When the replenishment carrier comprises a carrier core material and a coating resin that coats the surface of the carrier core material, a resin coated on the surface of the carrier core material (“coating resin”). Also referred to as a) is preferably a resin obtained by polymerizing a polymerizable monomer such as a vinyl monomer. Examples of such vinyl monomers include styrene-based, acrylic acid-based, methacrylic acid-based, alkyl acrylate-based, alkyl methacrylate-based and the like.

  Specific examples of the vinyl monomer include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-phenylstyrene, p-ethyl. Styrene or a derivative thereof such as styrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene or pn-laurylstyrene; Methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, methacrylic acid. Phenyl, metac Diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, cyclohexyl methacrylate, cyclopentyl methacrylate, cycloheptyl methacrylate, cyclooctyl methacrylate, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t acrylate -(Meth) acrylic acid ester such as butyl, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, phenyl acrylate or a derivative thereof (alkyl acrylate); ethylene, Olefins such as propylene and isobutylene; halogen-based vinyls such as vinyl chloride, vinylidene chloride, vinyl bromide, vinyl fluoride and vinylidene fluoride; vinyl propionate, vinyl acetate , Vinyl esters such as vinyl benzoate; vinyl ethers such as vinyl methyl ether and vinyl ethyl ether; vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and vinyl hexyl ketone; N-vinylcarbazole, N-vinylindole, N- Examples thereof include N-vinyl compounds such as vinylpyrrolidone; vinyl compounds such as vinylnaphthalene and vinylpyridine; and (meth) acrylic acid such as acrylonitrile, methacrylonitrile and acrylamide, or derivatives thereof.

  These vinyl monomers can be used alone or in combination of two or more kinds. The mixing ratio of two or more kinds is not particularly limited.

  Among the above, (meth) acrylic acid ester or its derivative (alkyl acrylate type) is preferable.

  Further, from the viewpoint that the amount of water adsorbed on the carrier core material is reduced, the environment difference in charging property is reduced, and the decrease in the amount of charge is suppressed particularly in a high temperature and high humidity environment, the vinyl monomer is alicyclic. It is preferable to contain a (meth) acrylic acid ester or a derivative thereof. Therefore, according to a preferred embodiment of the present invention, the replenishment carrier is configured to include a carrier core material and a coating resin that coats the surface of the carrier core material, and the coating resin is an alicyclic ring. It includes a resin derived from the formula (meth) acrylic acid ester or its derivative. By having such a configuration, it is possible to reduce the environmental difference in the charge amount, and it is possible to maintain the charge amount particularly in a high temperature and high humidity environment, and it is possible to suppress fog, toner scattering, and transfer rate reduction. it can. A resin obtained by polymerizing a monomer containing an alicyclic (meth) acrylic acid ester or a derivative thereof has appropriate mechanical strength and is appropriately film-abraded as a coating material (coating resin). By doing so, the surface of the carrier core material is refreshed. According to a preferred embodiment of the present invention, the initial carrier is also configured to include a carrier core material and a coating resin that coats the surface of the carrier core material, and the coating resin is an alicyclic resin. It includes a resin derived from a (meth) acrylic acid ester or its derivative.

  As specific examples of the alicyclic (meth) acrylic acid ester or its derivative, those having a cycloalkyl group having 5 to 8 carbon atoms are preferable, and specifically, cyclopentyl methacrylate, cyclohexyl methacrylate, cycloheptyl methacrylate. , Cyclooctyl methacrylate and the like. Among these, cyclohexyl methacrylate is particularly preferable from the viewpoint of mechanical strength and environmental stability of the charge amount.

  The glass transition point of the coating resin is not particularly limited, but is preferably 95 to 120 ° C. When the glass transition point of the coating resin is within the above range, excellent film-forming properties are exhibited, so that a dense coating layer is formed. The glass transition point of this coating resin is measured by a differential scanning calorimeter "DSC-7" (manufactured by Perkin Elmer Co., Ltd.). Specifically, 4.5 mg of the sample (coating resin) is precisely weighed to two decimal places, enclosed in an aluminum pan, and set in a sample holder. For the reference, an empty aluminum pan is used, and the temperature of Heat-Cool-Heat is controlled at a measurement temperature of 0 to 200 ° C., a temperature rising rate of 10 ° C./min, and a temperature lowering rate of 10 ° C./min. Analysis is performed based on the data in Heat. The glass transition point is the value of the intersection of the extension line of the baseline before the rise of the first endothermic peak and the tangent line showing the maximum slope between the rising portion of the first endothermic peak and the peak apex.

  The method for producing the coating resin can be applied by appropriately referring to a known method, for example, a known solvent (for example, water, sodium benzenesulfonate) and a monomer component are mixed, Polymerization can be carried out using a known polymerization initiator (eg potassium persulfate). In addition, from the viewpoint of particle size distribution and molecular weight, it is preferable to manufacture by an emulsion polymerization method or a miniemulsion polymerization method.

The weight average molecular weight of the coating resin is preferably 200,000 to 700,000. When the weight average molecular weight of the coating resin is within the above range, excellent film-forming properties are exhibited, so that a dense coating layer is formed. The weight average molecular weight of this coating resin is measured by gel permeation chromatography (GPC) of a tetrahydrofuran (THF) soluble component. The molecular weight measurement by GPC is specifically performed as follows. That is, using an apparatus “HLC-8220” (manufactured by Tosoh Corporation) and a column “TSKguardcolumn + TSKgelSuperHZM-M3 series” (manufactured by Tosoh Corporation), while maintaining the column temperature at 40 ° C., tetrahydrofuran (THF) was used as a carrier solvent at a flow rate of 0. Flow at 2 mL / min, and treat the sample at room temperature with an ultrasonic disperser for 5 minutes. Dissolve in tetrahydrofuran to a concentration of 50 mg / mL under dissolution conditions, and then treat with a membrane filter having a pore size of 0.2 μm. A sample solution is obtained by injecting 10 μL of this sample solution into the apparatus together with the above-mentioned carrier solvent, and detecting with a refractive index detector (RI detector), the molecular weight distribution of the sample is determined by using monodisperse polystyrene standard particles. It calculates using the calibration curve measured using. As the standard polystyrene sample for measuring the calibration curve, the molecular weights manufactured by Pressure Chemical Co., Ltd. are 6 × 10 ² , 2.1 × 10 ³ , 4 × 10 ³ , 1.75 × 10 ⁴ , 5.1 × 10 ⁴ , and 1. The calibration curve was obtained by measuring at least about 10 points of a standard polystyrene sample using those of 1 × 10 ⁵ , 3.9 × 10 ⁵ , 8.6 × 10 ⁵ , 2 × 10 ⁶ , 4.48 × 10 ^6. To create. A refractive index detector is used as the detector.

(Manufacturing method of supply carrier)
The method for producing the replenishing carrier is not particularly limited, but the carrier core material prepared as described above, the coating resin, and if necessary, an internal additive such as a resistance adjuster is mixed, and a mechanical impact force is added. Is preferred. Hereinafter, preferred embodiments will be described.

  Step (1): A carrier core material, coating resin particles (also referred to as “coating resin particles”) and, if necessary, a resistance adjusting agent are mixed, and the surface of the carrier core material is coated with resin particles and the like. To form carrier intermediate particles by adhering in layers.

  Step (2): a step of applying a mechanical impact force while heating the carrier intermediate particles to a temperature equal to or higher than the glass transition point of the coating resin to coat the carrier core material surface with the resin.

  Step (3): a step of cooling the carrier core material surface coated with a resin to room temperature.

  If necessary, the steps (1) to (3) may be repeated a plurality of times to form a resin coating layer having a desired layer thickness.

  In the method of passing through the above steps (1) to (3), since the organic solvent is not used, the resin coating layer becomes dense and strong without forming holes due to the organic solvent, and the adhesiveness to the carrier core material is improved. A carrier core material having a high resin coating layer can be formed.

Step (1): Carrier Intermediate Particle Forming Step From the viewpoint of particle size distribution and molecular weight, the coating resin particles used in this step (1) are preferably produced by an emulsion polymerization method or a miniemulsion polymerization method.

  The particle diameter of the resin particles for coating with which the surface of the carrier core material is coated is preferably 50 to 500 nm in volume average particle diameter, and more preferably 80 to 150 nm. The volume average particle diameter of the coating resin particles is measured by "MICROTRAC UPA-150" (manufactured by Nikkiso Co., Ltd.).

  In this step (1), in the case of a replenishing carrier, the amount of the coating resin particles added is 0.5 with respect to 100 parts by mass of the carrier core material from the viewpoint of achieving both durability of the carrier and low electric resistance. To 7.0 parts by mass, preferably 1.5 to 4.0 parts by mass, more preferably 2.5 to 4.16 parts by mass, still more preferably 2. It is 8 to 4.1. Therefore, according to a preferred embodiment of the present invention, in the case of the replenishing carrier, the mass of the coating resin is 1.5 to 4.0 parts by mass with respect to 100 parts by mass of the carrier core material. By setting the mass of the coating resin in such a range, the resistance value of the replenishing carrier can be set in an appropriate range, and fogging, toner scattering, transfer rate reduction, and carrier adhesion can be suppressed. Further, it is possible to suppress white spots in the lead portion.

  On the other hand, in the case of the initial carrier, which will be described later, the addition amount of the resin particles for coating is preferably 0.5 to 7.0 parts by mass, more preferably 1.5 to 7.0 parts by mass with respect to 100 parts by mass of the carrier core material. It is in the range of 6.0 parts by mass, more preferably 2.0 to 5.0 parts by mass, still more preferably 2.5 to 4.0 parts by mass.

  Further, the ratio of the amount of coating resin added to the replenishment carrier (parts by mass) / the amount of coating resin added to the initial carrier (parts by mass) is preferably more than 1 and 1.2 to 1.05. It is preferably 1.15. With such a ratio, there is a technical effect of stabilizing the carrier resistance in the developing device.

  As described above, when the amount of the coating resin added is within the above range, the charging property and the durability can be improved, and it becomes easy to control the above specific relationship. The resistance can be increased by increasing the addition amount of the coating resin, and the resistance can be decreased by decreasing the addition amount of the coating resin. The durability and durability can be improved.

  The amount of the resistance adjusting agent added as necessary is preferably 1 to 60 parts by mass with respect to 100 parts by mass of the coating resin.

Step (2): Step of applying resin coating to the surface of the carrier core material In this step (2), applying mechanical impact force means using an apparatus capable of applying mechanical impact force. Examples of such a device include a milling device having a rotor and a liner such as a turbo mill, a pin mill, and a kryptron, or a high speed stirring and mixing device having a (horizontal) stirring blade. Among these, it is preferable to use a high-speed stirring / mixing device having a (horizontal) stirring blade, because a uniform resin coating layer can be formed.

  In the case of the carrier for replenishment, the temperature and time for applying the mechanical impact force are first (1) about room temperature (for example, 15 to 35 ° C.) and mixed and stirred for 5 to 30 minutes, and then (2) as a heating temperature. It is advisable to mix and stir at 105 to 130 ° C. for 10 to 60 minutes. The latter heating temperature is not particularly limited to the range shown on the left, and is preferably (glass transition point of coating resin + 5 ° C) to (glass transition point of coating resin + 20 ° C). Of course, the step (2) may be directly performed without going through the step (1). It should be noted that the resin can be more uniformly covered on the surface of the carrier core material by performing the stirring twice or more in this way, and the generation of resin particles that do not cover the surface of the carrier core material can be suppressed. it can. The same applies hereinafter.

  In the case of the initial carrier described below, the temperature and time for applying the mechanical impact force are (1) room temperature (for example, 15 to 35 ° C.) and mixed and stirred for 5 to 30 minutes, and then (2) heating temperature. It is advisable to mix and stir at 105 to 130 ° C. for 10 to 60 minutes. The latter heating temperature is not particularly limited to the range shown on the left, and is preferably (glass transition point of coating resin + 5 ° C) to (glass transition point of coating resin + 20 ° C). Of course, the step (2) may be directly performed without going through the step (1).

  Here, by increasing the mixing time (treatment time) in the above (2), the density of the coating resin can be increased and the resistance can be lowered, while by shortening the mixing time (treatment time), the coating resin The density is reduced and the resistance can be increased. In the present invention, it is possible to control so as to satisfy the above-mentioned specific relationship by adjusting such a mixing time (processing time).

  The magnitude of the mechanical impact force is usually 3 to 20 m / sec, preferably 4 to 15 m / sec. Within such a range, there is an effect of suppressing the occurrence of blocking and, on the other hand, suppressing the destruction of the resin coating layer and the carrier core material.

-Step (3): Cooling step In this step (3), a known cooling treatment may be performed. Known cooling treatments include leaving the carrier having the resin coating layer at room temperature after the step (2) is completed.

  As a method for producing a resin-coated carrier, a resin-coated carrier may be produced using the high-speed stirring mixer shown in FIG. 1 of JP2012-103334A.

(Carrier resistance adjustment method)
As described above, the present invention is characterized in that the resistance value of the replenishing carrier and the resistance value of the initial carrier have a specific relationship. As a method of controlling so as to have such a specific relationship, in the above, adjustment of the temperature of the main firing (that is, adjustment of the resistance value of the carrier core material) and addition amount of the coating resin (coating used in the coating resin layer Adjustment of resin amount (resistance can be reduced by decreasing the amount of coating resin) and adjustment of mixing time of coating resin particles (treatment time when forming coating resin layer) (treatment during coating resin coating) Although it is possible to reduce the resistance by extending the time), it is also possible to adjust the addition amount of the resistance adjusting agent.

  However, considering the suppression of the fluctuation of the resistance value when the printer is used for a long period of time (that is, at the time of durability) and the reduction of the charge amount due to the transfer of the resistance adjusting agent to the toner, the coating resin particles It is preferable to adjust the carrier resistance by adjusting the addition amount (the amount of the coating resin used in the coating resin layer) and the mixing time of the coating resin particles (the processing time when forming the coating resin layer). In other words, according to the present invention, since the carrier resistance can be adjusted without adding the resistance adjusting agent, the resistance adjusting agent is not detached during the durability, and the toner can be transferred to the toner. Therefore, there is an effect that the generation of the toner with a low charge amount and the deterioration of the toner scattering do not occur.

(Replenishment toner)
The replenishment toner constituting the replenishment two-component developer of the present invention contains replenishment toner base particles and, if necessary, an external additive.

(Replenishment toner base particles)
The toner base particles for replenishment preferably contain a binder resin and a colorant, and may contain other additives (internal additives).

(Binder resin)
According to a preferred embodiment of the present invention, the binder resin contains a crystalline resin and an amorphous resin. According to a preferred embodiment of the present invention, the replenishment toner contains a crystalline polyester resin and an amorphous polyester resin as a binder resin. By using a crystalline resin such as a crystalline polyester resin as the binder resin, the low temperature fixability of the toner can be improved due to its sharp melt property, and the thermal energy at the time of fixing the toner image can be reduced. . By doing so, it is possible to solve problems such as higher printing speed, expansion of paper types, and reduction of environmental load.

  On the other hand, when the crystalline polyester resin and the amorphous resin (for example, the amorphous polyester resin) are mixed and used, the crystalline portion is melted when the melting point of the crystalline polyester resin is exceeded at the time of heat fixing, and The low temperature fixing can be achieved by compatibilizing the crystalline polyester resin and the amorphous resin (for example, the amorphous polyester resin). However, since the crystalline polyester has a low resistance value, if the resistance on the carrier side decreases, the charge amount of the toner decreases, which may cause fog to deteriorate the image quality. In addition, the transfer rate from the photoconductor to the transfer medium may decrease, or a phenomenon such as carrier adhesion may occur. On the other hand, according to the present invention, even if the crystalline polyester resin and the amorphous resin (for example, the amorphous polyester resin) are mixed and used, the decrease in the charge amount of the toner is suppressed and the fog is prevented. It is possible to prevent the deterioration of the image quality, suppress the decrease of the transfer rate from the photoconductor to the transfer medium, or suppress the occurrence of the phenomenon such as carrier adhesion. As described above, in the toner using the crystalline polyester, the resistance value on the toner side also decreases and it becomes difficult to maintain the charge amount. However, according to the present invention, the decrease in the charge amount is suppressed and the carrier resistance and Both the toner resistance and the toner resistance can be prevented from becoming low, the carrier resistance value can be controlled through durability, and the charge amount can be maintained, which reduces the thermal energy when fixing the toner image and provides a high-quality image. Compatibility is possible.

(Crystalline resin)
The crystalline resin includes a crystalline polyester resin, a crystalline polyurethane resin, a crystalline polyurea resin, a crystalline polyamide resin, a crystalline polyether resin, and the like. It is preferable to use a hydrophilic polyester resin. Therefore, according to a preferred aspect of the present invention, the crystalline resin is a crystalline polyester resin. The crystalline polyester resin will be described below.

  "Crystallinity" in the crystalline polyester resin means that there is a clear endothermic peak in the differential scanning calorimetry (DSC), not a stepwise endothermic change. It means that the half width of the endothermic peak when measured at (° C./min) is within 10 (° C.). On the other hand, a resin having a full width at half maximum of more than 10 ° C. or a resin showing a stepwise change in endotherm or having no clear endothermic peak means an amorphous polyester resin (amorphous polymer).

  The crystalline polyester resin is produced by using a known catalyst (for example, tin octylate or titanium tetraisopropoxide) and an acid component (for example, the following polyvalent carboxylic acid) and an alcohol component (for example, the following polyvalent carboxylic acid). It can be produced by a general polyester polymerization method of reacting with (alcohol).

  Examples of the polymerization method include a direct polycondensation method and a transesterification method, and the polymerization method is appropriately used depending on, for example, the kind of the monomer.

  The crystalline polyester resin can be produced, for example, at a polymerization temperature of 180 to 250 ° C. If necessary, the pressure in the reaction system is reduced, and the above monomers are reacted while removing water and alcohol generated by condensation. When the monomers are insoluble or incompatible at the reaction temperature, a solvent having a high boiling point may be added as a solubilizing agent and dissolved. In the polycondensation reaction, the solubilizing solvent is distilled off. When there is a poorly compatible monomer in the copolymerization reaction, for example, when the poorly compatible monomer and the acid or alcohol to be polycondensed with the monomer are condensed in advance and then polycondensed with the main component, Good.

  Moreover, you may contain the other binder resin. Examples of the crystalline polyester resin containing other binder resin include a modified crystalline polyester resin partially modified. The "partially modified" includes the crystalline polyester resin as "crystalline polyester polymerized segment" and "other polymerized segment", and the "other polymerized segment" as vinyl polymerized segment, amorphous It is meant to include a polymerizable polyester polymerized segment.

  Therefore, according to a preferred embodiment of the present invention, the crystalline polyester resin is a hybrid crystalline polyester resin in which the crystalline polyester polymerized segment is chemically bonded to another polymerized segment. By having such a constitution, the ratio of the polyester polymerized segment to the whole is reduced, whereby the water adsorption property can be reduced, and the reduction of the resistance value of the toner can be reduced. The other polymerized segment in the hybrid crystalline polyester resin is preferably in the range of 5 to 30% by mass. Within such a range, the effect of reducing the water adsorption property can be efficiently exhibited, and the low temperature fixing property can be improved.

  In the present invention, the hybrid crystalline polyester resin includes not only a graft type but also a block type.

  Further, according to a preferred embodiment of the present invention, the other polymerized segment is a vinyl polymerized segment. Since the resin component having the vinyl-based polymerized segment has a low water adsorption property, the vinyl-based polymerized segment can reduce the decrease in the resistance value of the toner.

  Examples of the modified crystalline polyester resin partially modified include a styrene- (meth) acrylic resin segment (vinyl polymerization segment).

  The styrene- (meth) acrylic resin has a molecular structure of a radical polymer of a compound having a radical-polymerizable unsaturated bond, and can be synthesized, for example, by radical polymerization of the compound. The above compounds may be one or more, examples of which include styrene and its derivatives, and (meth) acrylic acid and its derivatives.

  Examples of the styrene and its derivatives are styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, p-ethylstyrene and pn. -Butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-laurylstyrene, 2,4- Dimethylstyrene and 3,4-dichlorostyrene are included.

  Examples of the (meth) acrylic acid and its derivatives include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, methacrylic acid. Included are ethyl, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, ethyl β-hydroxyacrylate, γ-aminopropyl acrylate, stearyl methacrylate, dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate.

  The crystalline polyester resin has a molecular structure of a condensation polymerization product of a polyhydric carboxylic acid and a polyhydric alcohol, and can be synthesized by, for example, condensation polymerization of these.

  The polyvalent carboxylic acid may be one kind or more. Examples of the polyvalent carboxylic acid include an aliphatic dicarboxylic acid, an aromatic dicarboxylic acid, a dicarboxylic acid having a double bond, a trivalent or higher carboxylic acid, an anhydride thereof, and a lower alkyl ester thereof. . Of these, an aliphatic dicarboxylic acid is preferable in order to obtain a crystalline polyester resin.

  Examples of the above aliphatic dicarboxylic acid include oxalic acid, succinic acid, glutaric acid, adipic acid, speric acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12. -Dodecanedicarboxylic acid (tetradecanedioic acid), 1,14-tetradecanedicarboxylic acid, and 1,18-octadecanedicarboxylic acid.

  Examples of the aromatic dicarboxylic acid include phthalic acid, isophthalic acid, terephthalic acid, naphthalene-2,6-dicarboxylic acid, malonic acid, and mesaconinic acid.

  Examples of the dicarboxylic acid having a double bond include maleic acid, fumaric acid, 3-hexenedioic acid and 3-octenedioic acid. Of these, fumaric acid or maleic acid is preferable from the viewpoint of cost.

  Examples of the trivalent or higher carboxylic acid include 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, and 1,2,4-naphthalenetricarboxylic acid.

  The polyhydric alcohol may be one kind or more. Examples of the polyhydric alcohol include aliphatic diols and trihydric or higher alcohols. Of these, an aliphatic diol is preferable from the viewpoint of obtaining a crystalline polyester resin, and a linear aliphatic diol having a main chain having 2 to 20 carbon atoms is particularly preferable.

  When the aliphatic diol is the straight-chain type aliphatic diol, the crystallinity of the polyester is maintained and the decrease in the melting temperature of the polyester is suppressed. Therefore, it is excellent in toner blocking resistance, image storability and low-temperature fixability. In addition, it is practically easy to obtain the material. From these viewpoints, the carbon number of the main chain portion is more preferably 5 to 14.

  Examples of the aliphatic diol preferably used for the synthesis of the crystalline polyester resin include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol. 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol , 1,14-tetradecanediol, 1,18-octadecanediol and 1,14-eicosanedecanediol. Among them, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol or 1,10-decanediol is preferable from the viewpoint of easy availability.

  Examples of the trihydric or higher alcohol include glycerin, trimethylolethane, trimethylolpropane and pentaerythritol.

  The method for forming the styrene- (meth) acrylic resin is not particularly limited, and examples thereof include a method of polymerizing a monomer using a known oil-soluble or water-soluble polymerization initiator. Specific examples of the oil-soluble polymerization initiator include azo-based or diazo-based polymerization initiators and peroxide-based polymerization initiators shown below. The same applies to the following.

  Examples of the azo or diazo polymerization initiator include 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile and 1,1′-azobis (cyclohexane-1). -Carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobisisobutyronitrile and the like.

  As the peroxide-based polymerization initiator, benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, dicumyl peroxide, 2, 4-dichlorobenzoyl peroxide, lauroyl peroxide, 2,2-bis- (4,4-t-butylperoxycyclohexyl) propane, tris- (t-butylperoxy) triazine and the like can be mentioned.

(Amorphous resin)
Although the amorphous resin is not particularly limited, it is a resin that does not have a melting point and has a relatively high glass transition temperature (Tg) when differential scanning calorimetry (DSC) is performed on the resin. . In the DSC measurement, when the glass transition temperature in the first heating process is Tg1 and the glass transition temperature in the second heating process is Tg2, Tg1 of the amorphous resin is 35 to 80 ° C. The temperature is preferably 45 to 65 ° C. Further, the Tg2 of the above amorphous resin is preferably 20 to 70 ° C, and particularly preferably 30 to 55 ° C. The glass transition temperature (Tg1 and Tg2) and the Tg of the amorphous resin (particularly the amorphous polyester resin) can be obtained by using a differential scanning calorimeter according to ASTM D3418. The melting point of indium and zinc is used for the temperature correction of the detection unit of this device, and the heat of fusion of indium is used for the correction of the amount of heat. For the sample, an aluminum pan was used, an empty pan was set as a control, the temperature was raised at a heating rate of 10 ° C./min, the temperature was held at 200 ° C. for 5 minutes, and liquid nitrogen was used from 200 ° C. to 0 ° C. The temperature is lowered at 10 ° C./min, the temperature is held at 0 ° C. for 5 minutes, and the temperature is raised again from 0 ° C. to 200 ° C. at 10 ° C./min. Analysis is performed from the endothermic curve during the second temperature increase, and the onset temperature of the amorphous resin (particularly the amorphous polyester resin) is defined as Tg.

  The amorphous resin may be vinyl resin, urethane resin, urea resin, or the like. Further, the amorphous resin may be an amorphous polyester resin, and examples of the amorphous polyester resin include the following polycondensation polymers of polyvalent carboxylic acids and polyhydric alcohols.

  Moreover, you may contain the other binder resin. Examples of the amorphous polyester resin containing other binder resin include modified amorphous polyester resin partially modified. The "partially modified" means that the amorphous polyester resin includes "another polymerized segment" as an "amorphous polyester polymerized segment" and a vinyl polymerized segment as the "other polymerized segment". It is meant to include a crystalline polyester polymerized segment and the like.

  Therefore, according to a preferred embodiment of the present invention, the amorphous polyester resin is a hybrid amorphous polyester resin in which the amorphous polyester polymerized segment and another polymerized segment are chemically bonded. By having such a constitution, the ratio of the polyester polymerized segment to the whole is reduced, whereby the water adsorption property can be reduced, and the reduction of the resistance value of the toner can be reduced. The other polymerized segment in the hybrid amorphous polyester resin is preferably in the range of 5 to 30% by mass. Within such a range, the effect of reducing the water adsorption property can be efficiently exhibited, and the low temperature fixing property can be improved.

  In the present invention, the hybrid amorphous polyester resin includes not only the graft type but also the block type.

  Further, according to a preferred embodiment of the present invention, the other polymerized segment is a vinyl polymerized segment. Since the resin component having the vinyl-based polymerized segment has a low water adsorption property, the hybrid amorphous polyester resin having the vinyl-based polymerized segment can reduce the decrease in the resistance value of the toner.

  Examples of such a partially modified modified amorphous polyester resin include a segment of styrene- (meth) acrylic resin (vinyl polymerized segment).

  The styrene- (meth) acrylic resin has a molecular structure of a radical polymer of a compound having a radical-polymerizable unsaturated bond, and can be synthesized, for example, by radical polymerization of the compound. The above compounds may be one or more, examples of which include styrene and its derivatives, and (meth) acrylic acid and its derivatives.

  Examples of the styrene and its derivatives are styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, p-ethylstyrene and pn. -Butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-laurylstyrene, 2,4- Dimethylstyrene and 3,4-dichlorostyrene are included.

  Examples of the (meth) acrylic acid and its derivatives include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, methacrylic acid. Ethyl, butyl acrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, ethyl β-hydroxyacrylate, γ-aminopropyl acrylate, stearyl methacrylate, dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate are included.

  Examples of polyvalent carboxylic acids are aromatic carboxylic acids such as terephthalic acid, isophthalic acid, phthalic anhydride, trimellitic anhydride, pyromellitic acid, naphthalenedicarboxylic acid; maleic anhydride, fumaric acid, succinic acid, alkenyl. Aliphatic carboxylic acids such as succinic anhydride and adipic acid; alicyclic carboxylic acids such as cyclohexanedicarboxylic acid; their anhydrides and their lower (1 to 5 carbon atoms) alkyl esters. Among these polyvalent carboxylic acids, it is desirable to include an aromatic carboxylic acid.

  As the polyvalent carboxylic acid, a trivalent or higher carboxylic acid having a crosslinked structure or a branched structure (trimellitic acid or an acid anhydride thereof) may be used together with the dicarboxylic acid in order to secure the fixing property. These polyvalent carboxylic acids may be used alone or in combination of two or more.

  Examples of polyhydric alcohols are aliphatic diols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol and glycerin; cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A, etc. Alicyclic diols; and aromatic diols such as bisphenol A ethylene oxide adducts and bisphenol A propylene oxide adducts. Among these polyhydric alcohols, aromatic diols and alicyclic diols are desirable, and aromatic diols are more desirable.

  As the polyhydric alcohol, a trihydric or higher polyhydric alcohol having a crosslinked structure or a branched structure (glycerin, trimethylolpropane, pentaerythritol) may be used together with the diol in order to secure the fixing property. These polyhydric alcohols may be used alone or in combination of two or more.

  A chain transfer agent for adjusting the molecular weight of the obtained resin may be added to the monomer component used when the binder resin is synthesized. The chain transfer agent may be one kind or more, and is used in an amount capable of achieving the above object within the range in which the effects of the present embodiment are exhibited. Examples of the chain transfer agent include mercaptans such as 2-chloroethanol, octyl mercaptan, lauryl mercaptan and t-lauryl mercaptan, and styrene dimer.

(Colorant)
A colorant may be added to the replenishment toner base particles of the present invention. Known colorants can be used as the colorant.

  Specifically, examples of the colorant contained in the yellow toner include C.I. I. Solvent Yellow 19, the same 44, the same 77, the same 79, the same 81, the same 82, the same 93, the same 98, the same 103, the same 104, the same 112, the same 162, C.I. I. Pigment Yellow 14, the same 17, the same 74, the same 93, the same 94, the same 138, the same 155, the same 180, the same 185 and the like. These can be used alone or in combination of two or more. Among these, especially C.I. I. Pigment Yellow 74 is preferable. The content of the colorant contained in the yellow toner is preferably 1 to 10 parts by mass, and more preferably 2 to 8 parts by mass with respect to 100 parts by mass of the binder resin.

  Specifically, examples of the colorant contained in the magenta toner include C.I. I. Solvent Red 1, 49, 52, 58, 63, 111, 122, C.I. I. Pigment Red 5, 48: 1, 53: 1, 57: 1, 122, 139, 144, 149, 166, 177, 178, 222 and the like. These can be used alone or in combination of two or more. Among these, especially C.I. I. Pigment Red 122 is preferred. The content of the colorant contained in the magenta toner is preferably 1.00 to 7.00 parts by mass, more preferably 1.52 to 4.16 parts by mass, relative to 100 parts by mass of the binder resin. Is.

  Specifically, examples of the colorant contained in the cyan toner include C.I. I. Pigment Blue 15: 3 and the like. The content of the colorant contained in the cyan toner is preferably 1 to 20 parts by mass, and more preferably 2 to 15 parts by mass with respect to 100 parts by mass of the binder resin.

  Examples of the colorant contained in the black toner include carbon black and titanium black. Examples of carbon black include channel black, furnace black, acetylene black, thermal black, lamp black and the like.

(Internal additive)
The replenishment toner base particles of the present invention include an internal additive such as a charge control agent and a release agent, if necessary.

(Charge control agent)
The charge control agent is not particularly limited as long as it is a substance that can give positive or negative charge by frictional charging, and various known positive charge control agents and negative charge control agents can be used.

  The content of the charge control agent is preferably 0.01 to 30 parts by mass, and more preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the binder resin.

(Release agent)
Various known waxes can be used as the release agent.

  Examples of the wax include polyolefin wax such as polyethylene wax and polypropylene wax, branched hydrocarbon wax such as microcrystalline wax, long-chain hydrocarbon wax such as paraffin wax and sazol wax, and dialkyl such as distearyl ketone. Ketone wax, carnauba wax, montan wax, behenic acid behenate, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18-octadecanedioldi Ester wax such as stearate, tristearyl trimellitate, distearyl maleate, ethylenediamine behenylamide, tristearyl trimellitate Such as amide-based waxes such as bromide and the like.

  The content of the release agent is preferably 0.1 to 30 parts by mass, and more preferably 1 to 10 parts by mass with respect to 100 parts by mass of the binder resin.

(External additive)
An external additive may be added to the replenishment toner base particles of the present invention for the purpose of improving fluidity and chargeability. Examples of the external additive include inorganic oxide fine particles such as silica particles, alumina fine particles, and titanium oxide fine particles, and inorganic titanic acid such as strontium titanate and zinc titanate, which have a number average primary particle diameter of 5 to 30 nm. Inorganic particles such as compound particles may be used.

  From the viewpoint of heat resistant storage stability and environmental stability, the surface may be subjected to a hydrophobic treatment with a known surface treatment agent such as a coupling agent, and the surface treatment agent is particularly preferably dimethyldimethoxysilane, hexamethyl Examples thereof include disilazane (HMDS), methyltrimethoxysilane, isobutyltrimethoxysilane, and decyltrimethoxysilane.

(Method of manufacturing replenishment toner)
Next, a method of manufacturing the replenishment toner of the present invention will be described. The method for producing the replenishment toner base particles of the present invention is preferably an emulsion aggregation method. By adopting the emulsion aggregation method, the toner base particles for replenishment can be made smaller, and the generation of fine powder components can be suppressed, whereby replenishment toner particles having a sharp particle size distribution can be obtained. There is also an advantage that the energy required for manufacturing is small.

  In the production of a replenishment toner by the emulsion aggregation method, a plurality of types of fine particles (coloring agent, binder resin, release agent, etc.) having different particle surface properties, that is, aggregation stability, are used to grow the particle size.

  The emulsion aggregation method is a dispersion of binder resin fine particles containing a binder resin, a dispersion of colorant fine particles, a dispersion of components such as a release agent dispersion, which constitutes the toner base particles for replenishment, in an aqueous environment. A method of mixing below, aggregating them by adding an aggregating agent, controlling the particle size by adding an aggregating terminator if necessary, and controlling the shape by fusing. Produce particles.

  First, resin fine particles of a binder resin are formed, and the resin fine particles are aggregated and fused. More specifically, the binder resin fine particles (crystalline resin and / or amorphous resin) are put into an aqueous medium and dispersed to prepare a dispersion liquid of the binder resin fine particles. At this time, if necessary, the binder resin may contain a release agent in advance, or the release agent may be separately dispersed in an aqueous medium to prepare a release agent dispersion liquid. Good. At this time, a known surfactant (for example, anionic surfactant such as polyoxyethylene (2) sodium lauryl ether sulfate or sodium lauryl sulfate) may be appropriately used in advance for dispersion. The pH may be adjusted to about 8 to 11 with a pH adjusting agent (for example, sodium hydroxide). Further, the produced binder resin may be pulverized in advance to have a desired particle size.

  Separately, colorant fine particles are dispersed in an aqueous medium to prepare a colorant fine particle dispersion liquid. Also in this case, for the purpose of dispersion, the above-mentioned appropriate known surfactant may be used.

  Next, the binder resin fine particles, the release agent, and the colorant fine particles are aggregated in an aqueous medium, and these particles are fused to produce replenishment toner base particles. At this time, these may be aggregated together or may be aggregated in any order. In a preferred embodiment, the colorant particle dispersion liquid is added to an aqueous medium in which the resin particle dispersion liquid and the release agent dispersion liquid are mixed to form an alkali metal salt or an alkaline earth (Group 2) metal salt. And the like as an aggregating agent, and then heated at a temperature not lower than the glass transition temperature of the resin fine particles to promote aggregation and fuse the resin fine particles to each other. The temperature of the particle growth reaction at this time is preferably about 70 to 90 ° C., and the time is about 30 to 180 minutes. Then, when the size of the replenishment toner base particles reaches a target size, a salt (aggregation stopper) is added to stop aggregation.

  After that, the reaction system is heat-treated to be aged until the shape of the replenishment toner base particles becomes a desired shape, thereby completing the replenishment toner base particles. As the aging treatment, the liquid temperature is adjusted to 85 to 100 ° C., and the mixture is heated and stirred for 0.5 to 6 hours, and the particles are melted until the average circularity becomes 0.91 or more, preferably 0.920 to 0.996. Proceed with dressing.

  The volume-based median diameter can be measured by, for example, Coulter Multisizer 3 manufactured by Beckman Coulter, Inc. The average circularity can be measured by the method used in Examples described later. In addition, in the aging step, shearing due to heat and stirring is applied to the toner particles so that the resin fine particles in the agglomerated particles are fused and the circularity and surface property of the particles can be controlled.

(Flocculant)
The aggregating agent used in the agglomerated particle forming step is not particularly limited, but an agent selected from metal salts is preferred as one that grows particles by using a charge neutralization reaction and a crosslinking action. Examples of the metal salt include monovalent metal salts such as alkali metal salts such as sodium, potassium and lithium; divalent metal salts such as calcium, magnesium, manganese and copper; trivalent metal salts such as iron and aluminum. And so on. Specific metal salts include sodium chloride, potassium chloride, lithium chloride, calcium chloride, magnesium chloride, zinc chloride, copper sulfate, magnesium sulfate, manganese sulfate, aluminum sulfate, polyaluminum chloride, zinc acetate, and the like. Of these, it is particularly preferable to use a divalent metal salt because aggregation can be promoted with a smaller amount. These can be used alone or in combination of two or more.

(Aggregating agent)
As the aggregation stopping agent for stopping the growth of the aggregated particles, a salt that alleviates the aggregation action is used. For example, sodium chloride, polyvalent organic acids or salts thereof, amino acids, polyphosphonic acids or salts thereof can be used. Further, a method of reducing the aggregation action by changing the pH in the system can also be used.

  The replenishment toner base particles can be prepared as described above, and the replenishment toner can be prepared by adding the above-mentioned external additive by a known method (for example, mixing with a Henschel mixer or the like).

(Two-component developer for replenishment)
The replenishing carrier of the present invention becomes a replenishing two-component developer when combined with the above replenishing toner.

  That is, according to the present invention, there is provided a replenishing two-component developer including the replenishing carrier and the replenishing toner.

  The replenishment two-component developer of the present invention is produced by enclosing a replenishment carrier and a replenishment toner in a toner bottle so as to be preferably in the above range B, and shaking up and down about 10 times. can do.

  On the other hand, the initial two-component developer of the present invention uses an initial carrier and an initial toner in various known mixing devices such as a Turbuler mixer, a Henschel mixer, a Nauter mixer, and a V-type mixer (V blender). It is obtained by mixing. When using a V blender, the rotation speed is preferably 10 to 35 rpm, more preferably 15 to 30 rpm. The mixing time is preferably 10 to 30 minutes, more preferably 15 to 25 minutes. It is preferable that the initial carrier and the initial toner are mixed in advance under the conditions as described above so that they are sufficiently stirred and used in the developing device. The replenishing carrier and the replenishing toner can be sufficiently stirred in the developing device after being replenished in the developing device.

  The mixing ratio of the replenishment carrier and the replenishment toner is preferably 300 to 2,500 parts by mass, more preferably 500 to 2,000 parts by mass, relative to 100 parts by mass of the replenishment carrier.

  The mixing ratio of the initial carrier and the initial toner is preferably 5.00 to 9.00 parts by mass of the initial toner, and more preferably 6.00 to 8.20 parts by mass with respect to 100 parts by mass of the initial carrier. preferable.

(Initial carrier and initial toner)
Next, the initial carrier and the initial toner will be described.

  First, regarding the initial carrier, except that the carrier is manufactured so as to have the resistance value shown in Formula 1 and the above-mentioned specific relationship is satisfied, the explanation basically regarding the replenishing carrier is similarly valid. To do. Here, the carrier resistance adjusting method is as described above. Further, when explaining the replenishment carrier, there was a portion for explaining the initial carrier, but the initial carrier can be prepared by also referring to that part.

  Next, regarding the initial toner, from the viewpoint of maintaining the image quality, it is preferable to use the same toner as the replenishment toner. Here, the description of the replenishment toner similarly applies to the description of the initial toner.

(Image forming method)
The electrophotographic image forming method employing the auto-refining development method according to the present invention will be specifically described below.

  The replenishing carrier and the replenishing two-component developer of the present invention are used in a developing process in which an electrostatic latent image formed on an electrostatic latent image bearing member is visualized by a two-component developer containing a toner and a carrier. , An excess two-component developer is discharged from the developing device, and replenishment toner and replenishing carrier are replenished into the developing device, which is used in an electrophotographic image forming method employing a specific auto-refining development method. It is a thing.

  In such an electrophotographic image forming method, as long as a replenishing carrier having a specific relationship with the initial carrier contained in the developing device is used, other known materials can be used without any particular limitation.

  The electrophotographic image forming method adopting the auto-refining development method according to the present invention may be performed using a known image forming apparatus, for example, using the apparatus shown in FIG. 1 of JP-A-2014-240923. You can go. The image forming apparatus of FIG. 1 disclosed in the document includes an image reading unit, an operation display unit, an image processing unit, an image forming unit, a sheet conveying unit, a fixing unit, and a control unit.

  The image forming apparatus is an intermediate transfer type color image forming apparatus using an electrophotographic process technique. In the image forming apparatus, photosensitive drums corresponding to four colors of CMYK are arranged in series in the running direction (vertical direction) of the intermediate transfer belt, and a vertical tandem that sequentially transfers the toner images of the respective colors to the intermediate transfer belt in a single procedure. The method is adopted. That is, the image forming apparatus transfers (primarily transfers) the toner images of Y (yellow), M (magenta), C (cyan), and K (black) formed on the photosensitive drum to the intermediate transfer belt (intermediate transfer). An image is formed by superimposing toner images of four colors on the transfer belt and then transferring (secondarily transferring) the paper.

  According to a preferred embodiment of the present invention, there is provided an image forming method including a developing process for visualizing an electrostatic latent image formed on an electrostatic latent image carrier with a two-component developer containing a toner and a carrier. Therefore, the developing process is an auto-refining developing system in which an excessive two-component developer is discharged from the developing device and the above-mentioned replenishing two-component developer is replenished in the developing device. An image forming method is provided, wherein the mass of the initial carrier contained therein is 470 g or more.

  In the production printing field, it is expected that images with a high printing rate (blackened area rate) will be output continuously, and if the initial carrier mass is small at that time (if the initial two-component developer amount is small), new supply will be provided. The mixed time of the generated toner and the carrier is short, and the toner which is not sufficiently charged is developed. Therefore, when the initial carrier mass is a certain amount or more (particularly, 470 g or more), it is possible to suppress the occurrence of defects such as toner scattering and fog.

  Here, regarding the capacity of the developing device, for example, if the initial carrier mass is 470 g, a space of 293.75 cc is required as the bulk density of the developer initial carrier is 1.6 g / cc, and in reality, 1. The capacity of the developing device is required to be 352.5 cc with double the capacity. When the initial carrier amount is 470 g, it is difficult to follow an image with a printing rate of 100%, and therefore a developer of about 600 g is required. In that case, the developing device is about 450 cc. In the case of "bizhub Press (registered trademark) C1070" used in the evaluation method of the example, the initial developer amount is set to 620 g.

  Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In the examples, “parts” or “%” is used, but unless otherwise specified, “parts by weight” or “% by weight” is indicated. Unless otherwise specified, each operation is performed at room temperature (25 ° C).

<Production Example 1 of toner base particles>
(1) Preparation of Colorant Fine Particle Dispersion 11.5 parts by mass of sodium n-lauryl sulfate was added to 160 parts by mass of ion-exchanged water, and while stirring this solution, copper phthalocyanine (CI Pigment Blue 15: 3) was added. ) 24.5 parts by mass is gradually added, and then a dispersion treatment is performed using a stirrer "Clearmix (registered trademark) W Motion CLM-0.8" (manufactured by M Technique Co., Ltd.) to obtain a volume standard. A dispersion of fine colorant particles having a median diameter of 126 nm was prepared. This is designated as colorant fine particle dispersion [A].

(2) Preparation of Release Agent Dispersion Liquid After adding 50 parts by mass of paraffin wax (melting point: 73 ° C.), 2 parts by mass of sodium n-lauryl sulfate and 200 parts by mass of ion-exchanged water, the mixture was heated to 120 ° C. and IKA was added. After mixing and dispersing with Ultra Turrax (registered trademark) T50 manufactured by Co., Ltd., dispersion treatment was carried out with a pressure discharge type homogenizer to obtain a release agent dispersion liquid having a volume average particle diameter of 200 nm and a solid content of 20%. This is referred to as a release agent dispersion liquid [B].

(3) Preparation of dispersion liquid of amorphous polyester resin fine particles (3-1) Synthesis of amorphous polyester resin Add 2 mol of bisphenol A propylene oxide into a reaction tank equipped with a cooling pipe, a stirrer and a nitrogen introducing pipe. 360 parts by mass of the product, 80 parts by mass of terephthalic acid, 55 parts by mass of fumaric acid, and 2 parts by mass of titanium tetraisopropoxide as a polycondensation catalyst were added in 10 portions, and water generated at 200 ° C. under a nitrogen stream was added. The reaction was carried out for 10 hours while distilling off. Then, the mixture was reacted under a reduced pressure of 13.3 kPa (100 mmHg) and taken out when the softening point reached 104 ° C. to synthesize an amorphous polyester resin.

(3-2) Preparation of Amorphous Polyester Resin Particle Fine Dispersion 100 parts by mass of the obtained amorphous polyester resin was crushed with "Randel mill type: RM" (manufactured by Tokuju Seisakusho Co., Ltd.) to prepare 0 in advance. The mixture was mixed with 638 parts by mass of a sodium lauryl sulfate solution having a concentration of 0.26% by mass, and ultrasonically dispersed with V-LEVEL at 300 μA for 30 minutes using an ultrasonic homogenizer "US-150T" (manufactured by Nippon Seiki Seisakusho) while stirring. Amorphous polyester resin fine particle dispersion [1] having a volume-based median diameter (D ₅₀ ) of 250 nm was prepared.

(4) Preparation of Dispersion of Crystalline Polyester Resin Fine Particles (4-1) Synthesis of Crystalline Polyester Resin In a reaction tank equipped with a cooling pipe, a stirrer, and a nitrogen introducing pipe, 118 parts by mass of 1,6-hexanediol was added. , Tetradecanedioic acid (271 parts by mass) and titanium tetraisopropoxide (0.8 parts by mass) as a polycondensation catalyst were added in 10 batches and reacted for 5 hours while distilling off water generated under a nitrogen stream at 235 ° C. Let Then, the reaction was performed under a reduced pressure of 13.3 kPa (100 mmHg) for 1 hour to synthesize a crystalline polyester resin.

(4-2) Preparation of Crystalline Polyester Resin Particle Dispersion 100 parts by mass of the obtained crystalline polyester resin was crushed by "Landel mill type: RM" (manufactured by Tokuju Kosakusho Co., Ltd.) to prepare 0.26 parts by mass in advance. % Sodium lauryl sulphate solution 638 parts by mass, while stirring, ultrasonic homogenizer "US-150T" (manufactured by Nippon Seiki Seisakusho) is used to ultrasonically disperse V-LEVEL at 300 µA for 30 minutes, and based on volume. A crystalline polyester resin fine particle dispersion liquid [2] having a median diameter (D ₅₀ ) of 200 nm was prepared.

(5) Preparation of toner base particles <Production example of toner base particles 1>
In a reaction vessel equipped with a stirrer, a temperature sensor, and a cooling pipe, 250 parts by mass of the amorphous polyester resin fine particle dispersion liquid [1] in terms of solid content, and the crystalline polyester resin fine particle dispersion liquid [2] in terms of solid amount are calculated. After adding 50 parts by mass, 25 parts by mass of the release agent dispersion [B] in terms of solid content and 2000 parts by mass of ion-exchanged water, 5 mol / liter of sodium hydroxide aqueous solution was added to adjust the pH to 10. . Then, 40 parts by mass of the colorant fine particle dispersion [A] was added in terms of solid content. Then, an aqueous solution prepared by dissolving 60 parts by mass of magnesium chloride in 60 parts by mass of ion-exchanged water was added with stirring at 30 ° C. for 10 minutes. Then, the temperature was started after standing for 3 minutes, the temperature of this system was raised to 80 ° C. over 60 minutes, and the particle growth reaction was continued while maintaining 80 ° C. In this state, the particle diameter of the associated particles was measured with "Coulter Multisizer 3" (manufactured by Beckman Coulter, Inc.), and when the volume-based median diameter (D ₅₀ ) was 6.5 μm, sodium chloride 190 mass An aqueous solution in which 760 parts by mass of ion-exchanged water was dissolved was added to stop grain growth. Furthermore, the temperature is raised and the particles are heated and stirred at 90 ° C. to promote the fusion of the particles, and the toner average circularity measuring device “FPIA-2100” (manufactured by Sysmex) is used (HPF detection). When the measured average circularity reached 0.955, the temperature was cooled to 30 ° C. to prepare a dispersion liquid of toner base particles.

  The dispersion liquid of the toner base particles is subjected to solid-liquid separation with a centrifuge to form a wet cake of the toner base particles, and the wet cake is subjected to 35 with the centrifugal separator until the electric conductivity of the filtrate becomes 5 μS / cm. The toner base particles [1] were prepared by washing with ion-exchanged water at 0 ° C., transferring to a “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.), and drying until the water content was 0.5% by mass.

<Production Example 2 of toner base particles>
Except that the vinyl-modified amorphous polyester resin fine particle dispersion liquid [3] prepared as described below was used instead of the amorphous polyester resin fine particle dispersion liquid [1] in Production Example 1 of toner base particles. In the same manner, toner base particles [2] were prepared.

(6) Preparation of dispersion liquid of vinyl-modified amorphous polyester resin microparticles (6-1) Synthesis of vinyl-modified amorphous polyester resin Four 10 liter capacity equipped with nitrogen introduction tube, dehydration tube, stirrer and thermocouple In a one-necked flask,
Bisphenol A Propylene oxide 2 mol adduct 480 parts by mass Terephthalic acid 130 parts by mass Fumaric acid 85 parts by mass Esterification catalyst (tin octylate) 2 parts by mass were added, and polycondensation reaction was carried out at 230 ° C. for 8 hours, and further at 1 at 8 kPa. After reacting for a time and cooling to 160 ° C,
Acrylic acid 8.6 parts by mass Styrene 131 parts by mass Butyl acrylate 30 parts by mass Polymerization initiator (di-t-butyl peroxide) 10 parts by mass of a mixture was added dropwise by a dropping funnel over 1 hour, and after the addition, to 160 ° C. After the addition polymerization reaction is continued for 1 hour while maintaining the temperature, the temperature is raised to 200 ° C., the temperature is maintained at 10 kPa for 1 hour, and then acrylic acid, styrene, and butyl acrylate are removed to obtain a vinyl-modified amorphous polyester resin. (Hybrid amorphous polyester resin) was obtained.

(6-2) Preparation of Vinyl-modified Amorphous Polyester Resin Fine Particle Dispersion 100 parts by mass of the obtained vinyl-modified amorphous polyester resin was pulverized with "Randelmill type: RM" (manufactured by Tokuju Corporation), The mixture was mixed with 638 parts by mass of the prepared sodium lauryl sulfate solution having a concentration of 0.26% by mass, and the ultrasonic wave was homogenized with ultrasonic homogenizer “US-150T” (manufactured by Nippon Seiki Seisakusho Ltd.) for 30 minutes at 300 μA with V-LEVEL. Dispersion was performed to prepare a vinyl-modified amorphous polyester resin fine particle dispersion liquid [3] having a volume-based median diameter (D ₅₀ ) of 170 nm.

<Production Example 3 of toner base particles>
The same procedure as in Production Example 1 of toner base particles except that the vinyl-modified crystalline polyester resin fine particle dispersion liquid [4] prepared as described below was used in place of the crystalline polyester resin fine particle dispersion liquid [2]. Thus, toner base particles [3] were prepared.

(7) Preparation of dispersion liquid of vinyl-modified crystalline polyester resin fine particles (7-1) Synthesis of vinyl-modified crystalline polyester resin Four-necked 10 liter capacity equipped with nitrogen introduction tube, dehydration tube, stirrer and thermocouple In a flask,
Tetradecanedioic acid 271 parts by mass 1,6-hexanediol 118 parts by mass Titanium tetraisopropoxide 0.8 parts by mass was added, and polycondensation reaction was carried out at 230 ° C. for 8 hours, and further reacted at 8 kPa for 1 hour up to 160 ° C. After cooling
Acrylic acid 8.6 parts by mass Styrene 131 parts by mass Butyl acrylate 30 parts by mass Polymerization initiator (di-t-butyl peroxide) 10 parts by mass of a mixture was added dropwise by a dropping funnel over 1 hour, and after the addition, to 160 ° C. After the addition polymerization reaction was continued for 1 hour while maintaining the temperature, the temperature was raised to 200 ° C., the temperature was maintained at 10 kPa for 1 hour, and then acrylic acid, styrene, and butyl acrylate were removed to obtain a vinyl-modified crystalline polyester resin ( A hybrid crystalline polyester resin) was obtained.

(7-2) Preparation of Vinyl-Modified Crystalline Polyester Resin Fine Particle Dispersion 100 parts by mass of the obtained vinyl-modified crystalline polyester resin was crushed with "Randel mill type: RM" (manufactured by Tokuju Seisakusho Co., Ltd.) to prepare in advance. Mixing with 638 parts by mass of a sodium lauryl sulfate solution having a concentration of 0.26% by mass, ultrasonically dispersing with V-LEVEL, 300 μA for 30 minutes using an ultrasonic homogenizer “US-150T” (manufactured by Nippon Seiki Seisakusho) while stirring. A vinyl-modified crystalline polyester resin fine particle dispersion liquid [4] having a volume-based median diameter (D ₅₀ ) of 170 nm was prepared.

<Production Example 4 of toner base particles>
In Production Example 1 of toner base particles, a vinyl-modified amorphous polyester resin fine particle dispersion liquid [3] was used instead of the amorphous polyester resin fine particle dispersion liquid [1] instead of the amorphous polyester resin fine particle dispersion liquid [1]. Instead of using the vinyl-modified crystalline polyester resin fine particle dispersion [4], toner base particles [4] were prepared in the same manner.

<Preparation of Toners 1 to 4>
(External additive processing step)
(Addition of external additives)
1.0 mass% of hydrophobic silica (number average primary particle size 12 nm, hydrophobicity 68) and hydrophobic titanium oxide (number average primary particle size) were respectively added to the toner base particles [1] to [4] produced above. 20 nm, hydrophobicity 64) was added by 1.5% by mass. Toners [1] to [4] were manufactured by mixing using a "Henschel mixer" (manufactured by Nippon Coke Industry Co., Ltd.) and then removing coarse particles using a sieve having an opening of 45 μm.

<Production of carrier 1>
(Preparation of carrier core particle 1)
Raw materials were weighed so that MnO: 35 mol%, MgO: 14.5 mol%, Fe ₂ O ₃ : 50 mol% and SrO: 0.5 mol%, mixed with water, and then ground with a wet media mill for 5 hours. To obtain a slurry.

  The obtained slurry was dried with a spray dryer to obtain spherical particles. After adjusting the particle size of the particles, the particles were heated at 950 ° C. for 2 hours to perform calcination. After grinding with a wet ball mill for 1 hour using stainless beads having a diameter of 0.3 cm, it was further ground for 2 hours using zirconia beads having a diameter of 0.5 cm. 0.4% by mass of PVA as a binder was added to the solid content, then granulated by a spray dryer, dried, and held in an electric furnace at a temperature of 1250 ° C. for 5 hours for main firing.

After that, it was crushed, further classified, and the particle size was adjusted, and then the low-magnetic product was separated by magnetic separation to obtain carrier core material particles 1. The particle diameter (volume average particle diameter: D50) of carrier core particles is 32 μm, the resistance value is 8.26 × 10 ⁷ (Ω · cm), the saturation magnetization is 60.4 Am ² / kg, and the residual magnetization is 0.8 Am ^2. It was / kg. The particle size of the carrier core material particles was measured as follows.

(Carrier number average particle size measurement)
The volume-based median diameter (D50) of the magnetic particles (carrier core particles) was measured by a wet method using a laser diffraction particle size distribution measuring device "HEROS KA" (manufactured by Japan Laser Co., Ltd.). Specifically, first, an optical system with a focus position of 200 mm was selected, and the measurement time was set to 5 seconds. Then, the magnetic particles for measurement (carrier core particles) are added to a 0.2% sodium dodecyl sulfate aqueous solution and dispersed for 3 minutes using an ultrasonic cleaner "US-1" (manufactured by Asone Co.) for measurement. A sample dispersion was prepared, a few drops of this was supplied to "HEROS KA", and measurement was started when the sample concentration gauge reached the measurable region. With respect to the obtained particle size distribution, a cumulative distribution was prepared from the smaller diameter side with respect to the particle size range (channel), and the particle size with a cumulative 50% was defined as the volume average particle size D50.

(Measurement of magnetization)
The magnetization of the ferrite particles and the carrier were measured as follows. That is, a high-sensitivity vibrating sample magnetometer "VSM-P7-15 type" (manufactured by Toei Industry Co., Ltd.) was used as a measuring device, and the measurement magnetic field was -5000 / 4π A / m (using 25 mg of sample). The magnetization σ1000 (A · m ² / kg) at the magnetic field strength of 1000 / 4π A / m (1000 Oe) was obtained by gradually changing it from −5 kOe) to 5000 / 4π A / m (+5 kOe), and this value was obtained. Is the saturation magnetization.

The value of the residual magnetization was determined as the value of the magnetization (A · m ² / kg) at the strength of the magnetic field of 0 in the measurement of the magnetization.

(Preparation of carrier core material particles 2 to 3)
"Carrier core particle 2" to "carrier core particle 3" were prepared in the same manner as "carrier core particle 1" except that the conditions shown in Table 1 were used.

(Preparation of core coating resin)
Cyclohexyl methacrylate and methyl methacrylate were added at a "mass ratio = 50: 50" (copolymerization ratio) to an aqueous solution of 0.3% by mass of sodium benzenesulfonate to obtain 0.5% by mass of the total amount of monomers. A “coating material” was prepared by adding an amount of potassium persulfate corresponding thereto to carry out emulsion polymerization and drying by spray drying. The weight average molecular weight of the obtained coating material was 500,000.

(Production of carrier 1)
Into a high-speed stirring mixer equipped with a horizontal stirring blade, 100 parts by mass of "carrier core particles" prepared above as core particles and 3.2 parts by mass of "coating material" were charged, and the peripheral speed of the horizontal rotor was 8 m. / Sec, the mixture is mixed and stirred at 22 ° C for 15 minutes, and then mixed at 120 ° C for 50 minutes to coat the surface of the core particles with the coating material by the action of mechanical impact force (mechanochemical method). "Carrier 1" was manufactured.

(Production of carriers 2 to 12)
"Carrier 2" to "Carrier 12" were manufactured in the same manner as "Carrier 1" except that the conditions shown in Table 2 were used.

(Preparation of initial two-component developer)
An initial two-component developer was prepared by mixing 579.7 parts by mass (A) of the initial carrier having the resistance value (X) shown in Table 3 and 40.3 parts by mass of the initial toner shown in Table 3. The initial two-component developer was prepared by mixing the initial toner and the initial carrier using a V blender in an environment of normal temperature and normal humidity (temperature 20 ° C., relative humidity 50% RH). The rotation speed of the V blender was 20 rpm, the stirring time was 20 minutes, and the mixture was screened with a mesh having an opening of 125 μm. The mass of the initial toner was “40.3 parts by mass” in all the examples and comparative examples.

  As the “initial carrier having the resistance value (X) shown in Table 3”, one having the resistance value (X) shown in Table 3 is selected from the carrier types prepared above and used.

(Preparation of replenishment carrier and replenishment toner (replenishment two-component developer) bottle)
In the toner bottle (developer accommodating container 1) shown in FIG. 1, 990 parts by mass of the replenishment toner shown in Table 3 and a replenishment carrier having a resistance value (Y) shown in Table 3 are prepared as “replenishment carrier / replenishment carrier / replenishment carrier / replenishment carrier”. Two-component developer (replenishment toner + replenishment carrier) (mass%) "is enclosed as shown in (B) of Table 3 (for example, if 10 mass%, the replenishment carrier is 110 mass%). (Part addition) A toner bottle was prepared by shaking up and down 10 times. As the "replenishing carrier having the resistance value (Y) shown in Table 3", the carrier having the resistance value (Y) shown in Table 3 is selected from the carrier types prepared above and used.

  As shown in FIG. 1, the developer accommodating container 1 has a hollow container body 2 for accommodating the developer, a discharge member 3 attached to the container body 2, and a cap 4 attached to the discharge member 3. ing. The protruding portion 12 is formed in a spiral shape from the rear end portion of the container body 2 toward the front end portion. The direction of the spiral of the ridge 12 is set in correspondence with the rotation direction of the container body 2. The discharge member 3 is attached to the container body 2 so as to close the opening of the container body 2. Further, the mouth portion 16 is formed in a cylindrical shape. The developer accommodating container 1 shown in FIG. 1 is the same as that shown in Japanese Patent Laid-Open No. 2015-045815.

<Evaluation method>
Using the two-component developer obtained as described above, the developing method of the digital printing machine "bizhub PRESS (registered trademark) C1070" (manufactured by Konica Minolta Co., Ltd.) was changed to the normal developing method, and the following actual image was taken. Tested and evaluated.

(Adhering to carrier)
The image-free chart was developed at the initial stage and after printing 1.2 million sheets, the number of carriers attached to the surface of the photoconductor was counted in 5 fields of view by loupe observation, and the average number of carriers attached per 100 cm ² was regarded as carrier attachment. The carrier adhesion number of 50 or less was regarded as a practical level (pass), and 10 or less was evaluated as being particularly excellent. The "carrier" here is a mixture of the initial carrier and the replenishment carrier.

-Evaluation criteria-
◎: 10 or less,
◯: Greater than 10 and less than or equal to 30,
X: Greater than 30.

(Evaluation of toner scattering (dirt) in the machine)
Toner scattering (dirt) is determined by the following evaluation criteria by visually observing the toner scattering inside the machine after printing 1.2 million blank sheets in a high temperature and high humidity (30 ° C, 80% RH) environment. evaluated. If the evaluation is ◎ or ○, it is judged as passing. The "toner" here is a mixture of the initial toner and the replenishment toner.

-Evaluation criteria-
◎: The inside of the machine is not dirty with toner,
○: A state in which toner scattering is slightly seen in the machine,
×: Toner is scattered so much that maintenance inside the machine is required.

(Fog density)
First, the white paper density was calculated by measuring the absolute image densities at 20 locations using a reflection densitometer “RD-918 (manufactured by Macbeth)” and averaging the A4 size white paper before image formation.

In a normal temperature and normal humidity environment of a temperature of 20 ° C. and a relative humidity of 50%, 1.2 million sheets of character images with a print rate of 5% were printed on initial and A4 size fine paper, and then blank paper was printed. With respect to the blank paper, the absolute image densities at 20 locations were measured and averaged in the same manner as above to calculate the average density, and the value obtained by subtracting the blank paper density from the average density was evaluated as the fog density.
If the evaluation was ◯, it was judged as passed.

-Evaluation criteria-
◯: When the fog density is less than 0.010,
X: When the fog density is 0.010 or more.

(Lead part blank)
As shown in FIG. 2, when the patch image in which the solid portion BT and the halftone portion HT are adjacent to each other in the sub-scanning direction is developed by normal development, the phenomenon of "white spot in the lead portion" is caused by the solid portion BT and the halftone. This is a phenomenon in which the boundary portion of the halftone portion HT is white at the boundary of the portion HT (see Japanese Patent Application Laid-Open No. 2011-085640).

  FIG. 2A is a schematic diagram showing an example of a toner image in which the solid portion BT and the halftone portion HT are adjacent to each other in the sub-scanning direction, and FIG. 2B is a diagram showing the development area GR and the photosensitive drum 31Y. FIG. 6 is a schematic diagram showing a developing method (normal development) in which development is performed while the roller 46Y moves in the same direction.

  In a normal temperature and normal humidity environment with a temperature of 20 ° C. and a relative humidity of 50%, 1.2 million character images with a printing rate of 5% were printed on initial and A4 size fine paper, and then the image shown in FIG. White spot evaluation was carried out. If the evaluation was Δ or ○, it was determined to be acceptable.

-Evaluation criteria-
◯: No lead white spots occurred
Δ: White spots on the lead portion can be visually recognized, but within the allowable range,
X: Remarkably white spots are generated in the lead portion, which is outside the allowable range.

(Measurement of carrier resistance)
The carrier resistance of the present invention is a resistance dynamically measured under the developing condition with a magnetic brush (material: aluminum). The aluminum electrode drum of the same size as the photoconductor drum is replaced with the photoconductor drum, the carrier core material is supplied onto the developing sleeve to form a magnetic brush, and this magnetic brush is rubbed against the electrode drum, and this sleeve and drum The resistance of the carrier core material was determined by the following formula by applying a voltage (500 V) between the two and measuring the current flowing between them (measuring device: KEITHLEY, model number 6487).

DVR (Ωcm) = (V / I) × (N × L / Dsd),
DVR: Carrier resistance (Ωcm),
V: voltage (V) between developing sleeve and drum,
I: measured current value (A),
N: development nip width (cm),
L: developing sleeve length (cm),
Dsd: Distance between developing sleeve and drum (cm).

  In the present invention, the measurement was performed at V = 500V, N = 1 cm, L = 6 cm, and Dsd = 0.6 mm.

<Discussion>
As shown in Table 4, all the examples of the present invention are excellent because they suppress carrier adhesion, in-machine stain (toner scattering), fog, and white spots on the lead portion. More specifically, the carrier resistance is significantly prevented from deteriorating, the carrier is prevented from adhering, the lead resistance is significantly prevented from causing white spots in the lead portion, and the decrease in the charge amount is prevented, thereby suppressing toner scattering and fog. .

  On the other hand, in Comparative Example 1, the carrier 2 is used as the initial carrier, but the carrier 2 has an excessively high resistance due to an excessive amount of the coating resin added to the carrier core material, and therefore the carrier 2 has an initial value defined by the formula 1. The upper limit of the resistance value of the carrier is exceeded, and white spots in the lead portion occur.

  In Comparative Example 2, the carrier 3 is used as the initial carrier, but the resistance of the carrier 3 becomes too low because the amount of the coating resin added to the carrier core material is too small. Below the lower limit, carrier adhesion occurs, stains inside the machine occur, and fog also occurs.

  In Comparative Example 3, the carrier 9 is used as a carrier for replenishment, but the carrier 9 has a too short treatment time (120 ° C. mixing time), resulting in high resistance, and the carrier for replenishment calculated by the equation 2 is used. Exceeds the upper limit of the resistance value of. As a result, white spots in the lead portion have occurred.

  In Comparative Example 4, the carrier 10 is used as a replenishment carrier. The difference between Comparative Example 4 and Example 6 is basically the resin coating amount and the ratio (B) of the supply carrier. Although the former resin coating amount is not so different, the ratio (B) of the latter replenishing carrier is 15% by mass in Example 6 and 10% by mass in Comparative Example 4. Here, when the ratio (B) of the replenishing carrier is high, the amount of the replenishing carrier is large, so that the appropriate range of the resistance value changes. Due to the influence, in Comparative Example 4, the lower limit value of the resistance value of the replenishment carrier calculated by Equation 2 is exceeded. As a result, stains in the machine, fog, and white spots on the lead portion have occurred.

  In Comparative Example 5, the resistance value of the initial carrier is excessively high. In Comparative Example 6, the resistance value of the initial carrier is excessively high, while the resistance value of the replenishing carrier is excessively low. In Comparative Example 7, the resistance value of the initial carrier is excessively low. Further, in Comparative Example 9, the resistance value of the initial carrier is excessively low, and the resistance value of the replenishing carrier is also excessively low. Therefore, these also cannot achieve the intended purpose of the present invention.

1 ... developer container,
2 ... container body,
3 ... discharge member,
4 ... Cap,
12 ...
16 ... mouth,
31Y ... Photosensitive drum,
46Y ... Developing roller (developer carrying member),
BT ... solid part,
DL ... two-component developer,
HT ... Halftone part.

Claims (11)

An electrostatic latent image formed on an electrostatic latent image carrier, having a developing process of developing with a two-component developer containing a toner and a carrier, an image forming method,
The development process, together with the surplus of the two-component developer is discharged from the developing device, the auxiliary supply for a two-component developer is a auto-refining development method is replenished into the developing device,
The replenishment two-component developer contains a replenishment carrier and a replenishment toner,
The replenishment carrier has the following relationship with the initial carrier contained in the developing device, provided that X and Y are not the same value and X is not 2.4 × 10 ⁹ Ω · cm,
An image forming method, wherein the mass of the initial carrier contained in the developing device is 470 g or more.
The replenishing carrier is configured to include a carrier core material and a coating resin that coats the surface of the carrier core material,
The image forming method according to claim 1, wherein the coating resin includes a resin derived from an alicyclic (meth) acrylic acid ester or a derivative thereof. An electrostatic latent image formed on an electrostatic latent image carrier, having a developing process of developing with a two-component developer containing a toner and a carrier, an image forming method,
The development process, together with the surplus of the two-component developer is discharged from the developing device, the auxiliary supply for a two-component developer is a auto-refining development method is replenished into the developing device,
The replenishment two-component developer contains a replenishment carrier and a replenishment toner,
The replenishment carrier has the following relationship with the initial carrier contained in the developing device, provided that X and Y are not the same value, and the replenishment carrier is the carrier core material and the carrier core material. And a coating resin for coating the surface of the
The coating resin contains a resin derived from an alicyclic (meth) acrylic acid ester or a derivative thereof,
An image forming method, wherein the mass of the initial carrier contained in the developing device is 470 g or more.
The mass of the coating resin is, with respect to the carrier core material 100 parts by mass, or 1.5 to 4.0 parts by weight, the image forming method according to claim 2 or 3. The image forming method according to claim 1, wherein the value of X is relatively lower than the value of Y. The value of X is 2.00 × 10 ⁹ The image forming method according to claim 1, wherein the image forming method is (Ω · cm) or more. The image forming method according to claim 1, wherein at least one of the initial carrier and the replenishing carrier is a carrier other than a resin dispersion type carrier. The replenishment toner comprises a crystalline polyester resin and amorphous polyester resin, the image forming method according to any one of claims 1 to 7. The image forming method according to claim 8 , wherein the amorphous polyester resin is a hybrid amorphous polyester resin in which an amorphous polyester polymer segment and another polymer segment are chemically bonded. The image forming method according to claim 8 or 9 , wherein the crystalline polyester resin is a hybrid crystalline polyester resin in which a crystalline polyester polymerized segment and another polymerized segment are chemically bonded. Said other polymerized segment is a vinyl polymer segment, an image forming method according to claim 9 or 10.