JP2006330387A - Developer and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developer used in a hybrid developing device suitable for providing high image quality, and an image forming apparatus using the developer. <P>SOLUTION: The developer used in the hybrid developing device includes toner particles to which at least inorganic fine particles have been externally added and a carrier surface-covered with a resin coat, and has the following conditions (a)-(c); (a) a Vickers hardness (HVt) as the surface hardness of the toner particles is 12-18 (kg/mm<SP>2</SP>), (b) a Vickers hardness (HVc) as the surface hardness of the resin coat is ≤30 (kg/mm<SP>2</SP>), and (c) the Vickers hardness (HVt) of the toner particles, the Vickers hardness (HVc) of the resin coat and an average primary particle diameter d (nm) of the inorganic fine particles satisfy relational expression (1): 3(22-HVt)≤d≤(5/3)(HVc)(22-HVt). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a developer suitable for an image forming apparatus including a hybrid developing device and an image forming method using the developer. In particular, by using a developer in which the Vickers hardness of the toner particles, the Vickers hardness of the resin coating covering the carrier surface, and the average primary particle diameter of the inorganic fine particles satisfy a predetermined relationship, the inorganic fine particles are used. The present invention relates to a developer capable of preventing the surface of the toner, the surface of the resin coating, or the surface of the developing roll from being buried or detached, and an image forming method using them.

In general, an electrophotographic system including an image forming apparatus is roughly classified into a two-component developing system using a developer composed of toner and a carrier and a one-component developing system using only a toner not including a carrier. Further, as a development method combining these, there is a hybrid development method using a developer composed of a magnetic carrier and a non-magnetic toner.
While these three types of development methods require the use of specific developers corresponding to each of them, as a technique common to all, in order to improve the fluidity, inorganic fine particles such as silica and titanium oxide are removed. There is known a method for performing the additional processing.
By performing this external addition process, aggregation of the toners is suppressed, and the triboelectric charge amount of the toner can be controlled, so that stable fluidity can be obtained.

  Such inorganic fine particles are mainly composed of metal oxides such as silica, titanium oxide, alumina, magnetite, and zinc oxide. However, since these metal oxides generally have high hardness, there are cases where inorganic fine particles are buried in the toner particle surface or the carrier coating resin surface in the process of transporting the developer to the surface of the photoreceptor. In addition, inorganic fine particles sometimes contaminate the surface of the developing sleeve during the transfer process onto the developing roll. On the other hand, when the material is selected so as to increase the hardness of the toner particle surface or the carrier coating resin surface, the inorganic fine particles may be detached from those surfaces.

Therefore, in order to solve these problems, a toner used in a one-component development system composed of toner particles and an external additive, which has a Vickers hardness as the surface hardness of the toner particles and an average particle diameter of the external additive Discloses a non-magnetic one-component toner satisfying a predetermined relationship. (For example, see Patent Document 1)
JP 2004-163710 A (Claims)

However, as in Patent Document 1, under the conditions that are optimum under a specific use environment such as a one-component development method, a sufficient effect is not necessarily obtained in other development methods.
For example, in the hybrid developing method, since a carrier is present in addition to the toner, excessive stress is likely to be applied between the toner particles due to the presence of the carrier.
In this case, even if the conditions in Patent Document 1 are applied, there is a problem that the external additive is buried in or detached from the carrier surface or the toner surface, and a desired effect cannot be obtained. There was a case.

Therefore, the present invention has been made to solve the above-described problems, and is a developer used in a hybrid developing device, which has a Vickers hardness of toner particles, a Vickers hardness of a resin coating on a carrier surface, By using a developer that satisfies the predetermined relationship between the average primary particle size of the inorganic fine particles, it has been found that the inorganic fine particles can be prevented from being embedded or detached from the toner surface and the resin coating surface, The present invention has been completed.
That is, an object of the present invention is to provide a developer used in a hybrid developing apparatus suitable for providing high image quality and an image forming method using the developer.

According to the present invention, a developer transport body for charging the developer while magnetically holding it, a developing roll for transferring the developer from the transport body to form a thin layer of toner on the surface, And a developing device for applying a developing bias to the developing roll to perform latent image development of the latent image carrier, and the developer includes at least inorganic fine particles. A developer having the following constitutions (a) to (c) is provided, which includes toner particles subjected to an additive treatment and a carrier whose surface is coated with a resin film, and can solve the above-described problems. it can.
(A) Vickers hardness (HVt) as a surface hardness of the toner particles is a value within a range of 12 to 18 (kg / mm ² ).
(B) Vickers hardness (HVc) as the surface hardness of the resin coating is a value of 30 (kg / mm ² ) or less.
(C) The Vickers hardness (HVt) of the toner particles, the Vickers hardness (HVc) of the resin coating, and the average primary particle diameter d (nm) of the inorganic fine particles satisfy the following relational expression (1).
3 (22−HVt) ≦ d ≦ (5/3) (HVc) (22−HVt) (1)
That is, by using a developer in which the Vickers hardness of the toner particles, the Vickers hardness of the carrier coating resin, and the average primary particle diameter of the inorganic fine particles satisfy a predetermined relationship for the hybrid developing device, Stable image quality can be obtained over a long period of time while preventing the toner surface and the carrier coating resin surface from being buried or detached.

In constituting the developer of the present invention, the inorganic fine particles may include first inorganic fine particles having an average primary particle size of 30 nm or less and second inorganic fine particles having an average primary particle size of 40 nm or more. preferable.
With this configuration, toner fluidity and toner transferability can be obtained simultaneously.

In constituting the developer of the present invention, it is preferable that the inorganic fine particles are a single type or a combination of two or more types of silica, titanium oxide, aluminum oxide, magnetite and zinc oxide.
By comprising in this way, a material can be suitably selected according to the aspect of a developing agent.

According to another aspect of the present invention, there is provided an image forming method using any one of the developers described above.
That is, by using a developer that satisfies a predetermined condition for the hybrid developing device, the inorganic fine particles are buried in or detached from the toner surface or the carrier coating resin surface, or the surface of the developing roll by the detached inorganic fine particles. Can be prevented from being contaminated. Therefore, it is possible to obtain a balance between fluidity and transferability even in a stress-prone environment such as a hybrid developing device.

[First Embodiment]
The first embodiment includes a developer transport body for charging the developer while magnetically holding it, a developing roll for transferring the developer from the transport body to form a thin layer of toner on the surface, And a developing device for applying a developing bias to the developing roll to perform latent image development of the latent image carrier, and the developer includes at least inorganic fine particles. The developer includes externally-treated toner particles and a carrier whose surface is coated with a resin film, and has the following configurations (a) to (c).
(A) Vickers hardness (HVt) as a surface hardness of toner particles is a value within a range of 12 to 18 (kg / mm ² ).
(B) The Vickers hardness (HVc) as the surface hardness of the resin coating is a value of 30 (kg / mm ² ) or less.
(C) The Vickers hardness (HVt) of the toner particles, the Vickers hardness (HVc) of the resin coating, and the average primary particle diameter d (nm) of the inorganic fine particles satisfy the following relational expression (1).
3 (22−HVt) ≦ d ≦ (5/3) (HVc) (22−HVt) (1)
Hereinafter, the developer according to the first embodiment will be described by dividing it into constituent requirements.

1. Toner Particles (1) Basic Configuration The basic configuration of the toner particles used in the first embodiment is toner particles composed of a binder resin, a wax, a colorant, and a charge control agent. preferable.

(2) Binder resin The type of binder resin used in the developer used in the first embodiment is not particularly limited. For example, a styrene resin, an acrylic resin, and a styrene-acrylic copolymer are used. Thermoplastic resin such as polyethylene resin, polypropylene resin, vinyl chloride resin, polyester resin, polyamide resin, polyurethane resin, polyvinyl alcohol resin, vinyl ether resin, N-vinyl resin, styrene-butadiene resin It is preferable to use it.

(3) Waxes The waxes used for the toner used in the first embodiment are not particularly limited, and examples thereof include polyethylene wax, polypropylene wax, fluororesin-based wax, Fischer-Tropsch wax, One kind or a combination of two or more kinds of paraffin wax, ester wax, montan wax, rice wax and the like can be mentioned.

(4) Colorant The colorant used in the toner used in the first embodiment is not particularly limited, and examples thereof include carbon black, acetylene black, lamp black, aniline black, azo pigments, It is preferable to use yellow iron oxide, ocher, nitro dye, oil-soluble dye, benzidine pigment, quinacridone pigment, copper phthalocyanine pigment, and the like.

(5) Charge Control Agent It is also preferable to add a charge control agent to the toner used in the first embodiment. This is because the charge level and the charge rising characteristic (an index indicating whether the charge is charged to a constant charge level in a short time) are remarkably improved, and characteristics with excellent durability and stability can be obtained.
The type of the charge control agent is not particularly limited. For example, positive charge such as nigrosine, a quaternary ammonium salt compound, a resin type charge control agent in which an amine compound is bonded to a resin, and the like. It is preferable to use a charge control agent exhibiting properties.

(6) Surface Hardness Further, it is preferable to set the Vickers hardness (HVt) as the surface hardness of the toner particles to a value within the range of 12 to 18 (kg / mm ² ).
This is because inorganic fine particles as an external additive can be prevented from being buried or detached from the toner surface by combining with formula (1) described later and the Vickers hardness (HVc) of the resin coating. It is.
Here, the Vickers hardness can be measured by a method based on JIS B7725 and JIS Z2244 using a Vickers hardness meter or a dynamic ultra-micro hardness meter.

2. Carrier (1) Basic Configuration The carrier used in the first embodiment includes a carrier core and a resin film that covers the carrier core.

(2) Carrier core It is preferable to use magnetic powder as the carrier core constituting a part of the carrier. Preferred types of magnetic powder include metals or alloys exhibiting ferromagnetism such as ferrite, magnetite, iron, cobalt, and nickel, compounds containing these ferromagnetic elements, or appropriate heat treatments that do not contain ferromagnetic elements. An alloy that exhibits ferromagnetism when applied can be used.
Moreover, it is also preferable to use what was granulated by dispersing the above-mentioned magnetic powder in a binder resin such as a polyvinyl alcohol resin or a polyvinyl acetal resin as such a carrier core. That is, after mixing and dispersing magnetic powder, binder resin, and additives as required, granulated and dried, core particles can be obtained. Thereafter, the obtained carrier core elementary particles can be fired and pulverized using a known method to obtain a carrier core.
In addition, it is preferable to perform a granulation process using a spray dryer etc., for example. The firing process can be performed using, for example, an electric furnace or an infrared lamp. Moreover, it is preferable to perform a grinding | pulverization process using a hammer mill etc., for example. Furthermore, after the pulverization process, it is preferable to perform a classification process using an air classifier or the like.

(3) Resin coating As the resin coating, it is preferable to use a polyester resin, a polyethylene resin, a fluorine resin, an acrylic resin, a silicone resin, an epoxy resin, a phenol resin, or the like.
Moreover, it is preferable to make the coating amount of this coating material into the value within the range of 0.1-50 weight part with respect to 100 weight part of carrier cores. This is because when the amount of the coating material added is less than 0.1, the carrier core cannot be sufficiently coated and durability and chargeability tend to decrease. On the other hand, when the amount of the coating material added is greater than 50 parts by weight, the fluidity tends to decrease or the spent tends to occur.
Moreover, it is preferable that this coating | covering material is partially coat | covered around the carrier. This is because such a coating material partially covers the carrier, thereby improving fluidity and improving developability.

(4) Surface hardness Vickers hardness (HVc) as the surface hardness of the resin coating is a value of 30 (kg / mm ² ) or less.
This is because the inorganic fine particles as the external additive can be prevented from being embedded in the surface of the carrier resin film by combining with the formula (1) described later and the Vickers hardness (HVt) of the toner particles described above. Because. Moreover, it is because it can prevent that the adhesiveness of a toner particle and the resin film surface becomes high too much.
Therefore, it is preferable to set it as the value within the range of 10-25 (kg / mm < ² >), Furthermore, it is more preferable to set it as the value within the range of 12-20 (kg / mm < ² >).
Here, the Vickers hardness can be measured by a method based on JIS B7725 and JIS Z2244 using a Vickers hardness meter or a dynamic ultra-micro hardness meter.

(5) Production method The carrier production method is not particularly limited. For example, the carrier core is coated with a coating material and, if necessary, an additive, and then crushed. It is preferable to manufacture by classifying.
For example, the coating process is preferably performed using a spraying method, a dipping method, or the like, and specifically, performed using a fluidized bed granulator or the like.
Moreover, it is preferable to perform a crushing process using a hammer mill etc., for example. Furthermore, after the pulverization process, it is preferable to perform a classification process using an air classifier or the like.

3. Inorganic Fine Particles (1) Material In addition, inorganic fine particles can be added as an external additive to the toner particles described above.
At this time, the material of the inorganic fine particles is preferably a single type of silica, titanium oxide, or aluminum oxide, or a combination of two or more types.
In addition, when silica is used, it is preferable to use a hydrophobized silica by a silicone oil treatment because the charging characteristics can be further improved. Further, when using titanium oxide, a hydrophobized titania by a titanate coupling agent is used. preferable. As the titanium oxide, either anatase type titanium oxide or rutile type titanium oxide can be suitably used.

(2) Average primary particle diameter The average primary particle diameter d (nm) of the inorganic fine particles satisfies the relationship of the following relational expression (1).
3 (22−HVt) ≦ d ≦ (5/3) (HVc) (22−HVt) (1)
At this time, the Vickers hardness (HVt) of the toner particles and the Vickers hardness (HVc) of the resin film can each be a value within the above-described range.
That is, the Vickers hardness (HVt) of the toner particles can be set to 12 to 18 (kg / mm ² ), and the Vickers hardness (HVc) of the resin coating can be set to 30 (kg / mm ² ) or less.
When these relationships are illustrated, the hatched area (R) in the graph shown in FIG. 1 corresponds to this condition range. However, since the variable (HVc) is included on the right side of Equation (1), the region (R) changes corresponding to the value of HVc.

Here, the graph shown in FIG. 1 is a characteristic graph in which the vertical axis represents the average primary particle diameter (d) of the inorganic fine particles and the horizontal axis represents the Vickers hardness (HVt) of the toner particles.
In such a characteristic graph, the straight line indicated by the line segment (A) corresponds to the left side in the equation (1). That is, the line segment (A) is a straight line represented by d = 3 (22−HVt).
Further, the straight line indicated by the line segment (B) corresponds to the right side in the equation (1). That is, the line segment (B) is a straight line represented by d = (5/3) (HVc) (22−HVt).
The line segment (B) shown in FIG. 1 illustrates the case where the value of HVt is 30 (kg / mm ² ) which is the maximum value.
The straight line indicated by the line segment (C) corresponds to a straight line when the HVc is 12 (kg / mm ² ) which is the minimum value, and the straight line indicated by the line segment (D) is HVc. Corresponds to a straight line when the maximum value is 18 (kg / mm ² ).
That is, the region (R) surrounded by these line segments (A) to (D) represents the above-described formula (1), the range of the Vickers hardness (HVt) of the toner particles, and the Vickers hardness (HVc) of the resin film. ) Range, and the maximum area that can satisfy.
From the relationship between the Vickers hardness of the toner particles and the primary average particle diameter of the inorganic fine particles, when the primary average particle diameter of the inorganic fine particles is less than the line segment (A) in FIG. 1, toner embedding becomes remarkable, and the line in FIG. When the minute (B) is exceeded, toner desorption becomes significant.

Moreover, it is preferable that an inorganic fine particle contains the 1st inorganic fine particle with an average primary particle diameter of 30 nm or less, and the 2nd inorganic fine particle with an average primary particle diameter of 40 nm or more.
The reason for this is that the fluidity can be maintained by including fine inorganic fine particles having a particle size of 30 nm or less, and the transferability can be improved by including relatively large inorganic fine particles having a particle size of 40 nm or more. This is because it can.
The mixing ratio of inorganic fine particles having an average primary particle size of 30 nm or less and inorganic fine particles of 40 nm or more can be selected depending on the balance between desired fluidity and polishing effect. For example, the ratio is 90:10 in terms of specific surface area. It is preferable to set the value within a range of ˜50: 50.
The number average primary particle size of the inorganic fine particles is measured by a photograph of the toner magnified by a scanning electron microscope, and further contains an inorganic fine powder by an elemental analysis means such as XMA attached to the scanning electron microscope. Measured by measuring 100 or more primary particles of inorganic fine powder adhering to or liberating from the toner surface and obtaining the average primary particle size based on the number while contrasting the photograph of the toner mapped with the element. it can.

4). Hybrid Development Device (1) Basic Configuration A hybrid development device used in the present invention includes a developer transport body for charging a developer while magnetically holding it, a developer transported from the transport body, and toner on the surface thereof. A developing device for applying a developing bias to a developing roll for forming a thin layer and developing a latent image on the latent image carrier can be provided.

(2) Operation Hereinafter, the configuration of the hybrid developing device 100 will be described with reference to FIG.
The hybrid developing device 100 includes a magnetic roller (supply roller) 25a and a developing roller 26a. Among these, the magnetic roller 25a is made of a nonmagnetic metal material and has a cylindrical rotating sleeve 31a and a fixed fixing member disposed therein. The fixed magnet body 31b has a plurality of magnetic poles. The magnetic roller 25a and the developing roller 26a are disposed in the developing container 32. A DC bias Vdc1 is applied from the direct current (DC) bias power source 33a to the developing roller 26a, and an AC bias Vac is applied from the alternating current (AC) bias power source 33b. Furthermore, a DC bias Vdc2 is applied from the direct current (DC) bias power supply 34 to the magnetic roller 25a. The bias power supplies 33a and 34 are controlled by a control device (not shown).

  The developing container 32 includes a paddle mixer 35 and a stirring mixer 36, and a partition plate 37 is disposed between the paddle mixer 35 and the stirring mixer 36. Then, the two-component developer in the developing container 32 is charged while being stirred and conveyed by the stirring mixer 36. The developer is supplied to the magnetic roller 25 a while being stirred and charged by the paddle mixer 35. Further, a head cutting blade (layer thickness regulating blade) 38 is provided facing the magnetic roller 25a, and the height of the magnetic brush formed on the magnetic roller 25a is regulated by the layer thickness regulating blade 38. Note that the length of the partition plate 37 (the axial direction of the developing roller 26a) is shorter than the width of the developing container 32 so that the developer can freely pass through both ends of the partition plate 37.

The toner layer thickness on the developing roller 26a is determined according to the absolute value ((Vdc2) − (Vdc1)) (hereinafter referred to as a delta value) of the potential difference between the DC bias (Vdc2) and the DC bias (Vdc1). Be regulated. For example, when the delta value is increased, the toner thin layer on the developing roller 26a is thickened. Conversely, when the delta value is decreased, the toner thin layer is thinned.
Therefore, in such a state where the thickness of the toner thin layer is controlled, the toner from the toner thin layer on the developing roller 26a onto the photosensitive drum 27a according to the potential difference between the photosensitive drum 27a and the developing roller 26a. Hybrid development is performed by flying to the formed electrostatic latent image.
That is, under such a configuration of the hybrid developing device, a developer in which the Vickers hardness of the toner particles, the Vickers hardness of the carrier coating resin, and the average primary particle diameter of the inorganic fine particles satisfy a predetermined relationship is hybridized. By using it in the developing device, it is possible to obtain stable image quality over a long period of time while preventing the inorganic fine particles from being buried or detached from the toner surface and the carrier coating resin surface.

[Second Embodiment]
The second embodiment includes a developer transport body for charging the developer while magnetically holding it, a developing roll for transferring the developer from the transport body to form a thin layer of toner on the surface, A developer used in a hybrid developing device including a developing device that applies a developing bias to the developing roll to develop a latent image on a latent image carrier, and at least inorganic fine particles are externally added. An image forming method comprising: a toner particle; and a carrier having a surface coated with a resin film, wherein a developer having the following configurations (a) to (c) is used.
(A) Vickers hardness (HVt) as a surface hardness of toner particles is a value within a range of 12 to 18 (kg / mm ² ).
(B) The Vickers hardness (HVc) as the surface hardness of the resin coating is a value of 30 (kg / mm ² ) or less.
(C) The Vickers hardness (HVt) of the toner particles, the Vickers hardness (HVc) of the resin coating, and the average primary particle diameter d (nm) of the inorganic fine particles satisfy the following relational expression (1).
3 (22−HVt) ≦ d ≦ (5/3) (HVc) (22−HVt) (1)

Hereinafter, the contents already described in the first embodiment will be omitted with reference to FIG. 3, and the configuration of the image forming apparatus using the developer used in the hybrid developing apparatus and the image formation will be described as the second embodiment. The method will be mainly described.
FIG. 3 is a diagram showing a color image forming apparatus 20 as an example of an image forming apparatus using a developer according to the first embodiment of the present invention. The color image forming apparatus 20 includes an endless belt (conveying belt) 21, and the endless belt 21 is configured to convey the recording paper fed from the paper feeding cassette 22 toward the fixing device 23. Has been. On the upper side of the endless belt 21, a black developing device 24a, a yellow developing device 24b, a cyan developing device 24c, and a magenta developing device 24d, which are hybrid developing devices, are each along the conveyance direction of the recording paper. Are arranged. The hybrid developing devices 24a to 24d are provided with supply rollers (magnetic rollers) 25a to 25d and developing rollers 26a to 26d, respectively. A layer can be formed.

Photosensitive drums 27a to 27d, which are image carriers, are arranged facing the developing rollers 26a to 26d, respectively. Further, around the photosensitive drums 27a to 27d, chargers 28a to 28d and exposure devices 29a to 29d are arranged, respectively. Then, after the photosensitive drums 27a to 27d are charged by the chargers 28a to 28d, the photosensitive drums 27a to 27d are exposed by the exposure devices 29a to 29d according to the image data. In this manner, electrostatic latent images are formed on the photosensitive drums 27a to 27d. Next, the electrostatic latent images on the photosensitive drums 27a to 27d are developed by the developing rollers 26a to 26d, and toner images of respective colors are formed.
Further, the color toner images are sequentially transferred onto the recording paper conveyed by the endless belt 21 by the transfer devices 30a to 30d to form a color toner image. Thereafter, the recording paper is sent to the fixing device 23, where the color toner image is fixed, and the recording paper is discharged via a paper discharge path.

1. Carrier synthesis (1) Carrier A synthesis method F51-50 (50 μm, manufactured by Powdertech Co., Ltd.) 10 kg, Epicote 1004 (Japan Epoxy Resin ( 2 kg) was dissolved and then coated in 20 L of acetone mixed with 100 g of diethylenetriamine and 150 g of phthalic anhydride while hot air at 80 ° C. was fed. This was heated at 180 ° C. for 1 hour with a dryer to prepare Carrier A.

(2) Method for synthesizing carrier B After coating in the same manner as carrier A, carrier B was prepared by heating at 180 ° C. for 2 hours in a dryer.

(3) Method of synthesizing carrier C After coating with 200 g of diethylenetriamine to be added and 300 g of phthalic anhydride, the carrier C was heated at 190 ° C. for 2 hours in a dryer.

(4) Method of synthesizing carrier D After coating in the same manner as carrier A, carrier D was prepared by heating at 160 ° C. for 1 hour in a dryer.

2. Preparation of inorganic fine particles (1) Particle size adjustment Silica was used as a raw material for inorganic fine particles, and silica having a desired average primary particle size was prepared by the method described below.
As the silica having an average primary particle size of 7 nm, 12 nm, 20 nm, 30 nm, and 40 nm, fumed silica Aerosil 300, Aerosil 200, Aerosil 90, Aerosil 50, and Aerosil Ox50 manufactured by Nippon Aerosil Co., Ltd. were used, respectively.
Moreover, Nippon Shokubai Co., Ltd. Sea Hoster KE-P10, KE-P30, and KE-P50 were used for the silica with an average primary particle diameter of 100 nm, 300 nm, and 500 nm.
Further, silica particles having an average primary particle size of 150 nm, 200 nm, 250 nm, and 400 nm were adjusted in particle size by mixing Seahosters KE-P10, KE-P30, and KE-P50 at a constant ratio.

(2) Hydrophobization treatment Next, these silicas were subjected to a hydrophobic treatment by the following method.
Silica having an average primary particle size of 12 nm is composed of 2 parts by weight of silica, 0.8 part by weight of dimethyl silicone oil (sometimes referred to as dimethylpolysiloxane), 3-aminopropyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd.) 0.2 parts by weight) was stirred for 30 minutes while being irradiated with ultrasonic waves at room temperature.
Subsequently, toluene was distilled off using a rotary evaporator, and the obtained solid was dried with a vacuum dryer at a set temperature of 50 ° C. until it was not reduced. Furthermore, heat treatment was performed at 200 ° C. for 3 hours in a nitrogen stream in an electric furnace. The obtained powder was crushed by a jet mill and collected by a bag filter.
About the silica of the other average primary particle diameter, the same hydrophobization process was performed by the following compounding quantities. That is, 1.2 parts by weight for an average primary particle diameter of 7 nm, 3.5 parts by weight for an average primary particle diameter of 20 nm, 5 parts by weight for an average primary particle diameter of 30 nm, and an average primary particle diameter of 40 nm 7 parts by weight, 20 parts by weight for an average primary particle diameter of 100 nm, 30 parts by weight for an average primary particle diameter of 150 nm, 40 parts by weight for an average primary particle diameter of 200 nm, 50 parts by weight for an average primary particle diameter of 250 nm In the case of an average primary particle size of 300 nm, 60 parts by weight, in the case of an average primary particle size of 400 nm, 80 parts by weight, and in the case of an average primary particle size of 500 nm, 100 parts by weight.

3. Production of Developer (1) Production Method of Developer A 100 parts by weight of styrene-acrylic resin as binder resin, 4 parts by weight of release agent, 12 parts by weight of carbon black as colorant, 1 part by weight of charge control agent Each was put into a Henschel mixer and mixed, then melt kneaded with a twin screw extruder and cooled with a drum flaker.
Next, after coarsely pulverizing with a hammer mill, finely pulverizing with a turbo mill and classifying using an air classifier, toner particles having a volume average particle size of 7.67 μm and an average circularity of 0.932 were prepared.
Next, with respect to 100 parts by weight of the toner particles, primary particle diameters of 30 nm and 100 nm silica hydrophobized with dimethyl silicone oil and 3-aminopropyltrimethoxysilane as external additives are each 80% in terms of the coverage in terms of specific surface area. % And 20%, and the mixture was stirred and mixed with a Henschel mixer to obtain toner A.
Finally, toner A and carrier A were blended so that the toner concentration was 8 parts by weight of the carrier, and developer A was prepared by stirring and mixing uniformly with a Nauta mixer.

(2) Preparation Method of Developer B Toner particles having a volume average diameter of 7.83 μm and an average circularity of 0.928 were prepared in the same manner as toner A except that a polyester resin was used as the binder resin.
Next, with respect to 100 parts by weight of the toner particles, primary particle diameters of 12 nm and 40 nm silica hydrophobized with dimethyl silicone oil and 3-aminopropyltrimethoxysilane are respectively 80% and 20% in terms of specific surface area coverage. Toner B was obtained.
Finally, the toner B and the carrier A were blended so that the toner concentration was 8 parts by weight of the carrier, and the developer B was prepared by uniformly stirring and mixing with a Nauta mixer.

(3) Production method of developer C A volume average diameter of 7.76 μm and an average circularity of 0.930 are the same as those of the toner A except that a styrene-acrylic resin containing a release agent is used as a binder resin. Toner particles were prepared. Next, with respect to 100 parts by weight of the toner particles, primary particle diameters of 20 nm and 100 nm silica hydrophobized with dimethyl silicone oil and 3-aminopropyltrimethoxysilane are respectively 80% and 20% in terms of specific surface area coverage. Toner C was obtained.
Finally, the toner C and the carrier A were blended so that the toner concentration was 8 parts by weight of the carrier, and the developer C was prepared by uniformly stirring and mixing with a Nauta mixer.

(4) Preparation method of developer D For 100 parts by weight of toner particles prepared in the same manner as toner A, silica particles having primary particle sizes of 30 nm and 250 nm hydrophobized with dimethyl silicone oil and 3-aminopropyltrimethoxysilane were used. Toner D was obtained by adding the specific surface area coverage to 80% and 20%, respectively.
This toner D and carrier A were blended so that the toner concentration would be 8 parts by weight of the carrier, and the developer D was prepared by uniformly stirring and mixing with a Nauta mixer.

(5) Preparation method of developer E For 100 parts by weight of toner particles prepared in the same manner as toner B, primary particle sizes 12 nm and 100 nm silica hydrophobized with dimethyl silicone oil and 3-aminopropyltrimethoxysilane were used. Toner E was obtained by adding the specific surface area coverage to 80% and 20%, respectively.
The toner D and the carrier A were blended so that the toner concentration was 8 parts by weight of the carrier, and the developer E was prepared by uniformly stirring and mixing with a Nauta mixer.

(6) Preparation Method of Developer F For 100 parts by weight of toner particles prepared in the same manner as toner B, silica particles having primary particle sizes of 20 nm and 40 nm hydrophobized with dimethyl silicone oil and 3-aminopropyltrimethoxysilane were used. Toner F was obtained by adding 80% and 20% of the specific surface area coverage.
The toner F and carrier A were blended so that the toner concentration was 8 parts by weight of the carrier, and the developer F was prepared by uniformly stirring and mixing with a Nauta mixer.

(7) Preparation method of developer G For 100 parts by weight of toner particles prepared in the same manner as toner B, primary particle sizes 20 nm and 100 nm silica hydrophobized with dimethyl silicone oil and 3-aminopropyltrimethoxysilane were used. Toner G was obtained by adding the specific surface area coverage to 80% and 20%, respectively.
The toner G and the carrier A were blended so that the toner concentration was 8 parts by weight of the carrier, and the developer G was prepared by uniformly stirring and mixing with a Nauta mixer.

(8) Preparation method of developer H For 100 parts by weight of toner particles prepared in the same manner as toner A, silica particles having primary particle sizes of 30 nm and 400 nm hydrophobized with dimethyl silicone oil and 3-aminopropyltrimethoxysilane were used. Toner H was obtained by adding the specific surface area coverage to 80% and 20%, respectively.
This toner H and carrier B were blended so that the toner concentration would be 8 parts by weight of the carrier, and the developer H was prepared by uniformly stirring and mixing with a Nauta mixer.

(9) Preparation Method of Developer I For 100 parts by weight of toner particles prepared in the same manner as toner B, silica particles having primary particle sizes of 12 nm and 150 nm hydrophobized with dimethyl silicone oil and 3-aminopropyltrimethoxysilane were used. Toner I was obtained by adding the specific surface area coverage to 80% and 20%, respectively.
This toner I and carrier B were blended so that the toner concentration would be 8 parts by weight of the carrier, and developer I was prepared by stirring and mixing uniformly with a Nauta mixer.

(10) Preparation method of developer J For 100 parts by weight of toner particles prepared in the same manner as toner A, silica particles having primary particle sizes of 30 nm and 500 nm hydrophobized with dimethyl silicone oil and 3-aminopropyltrimethoxysilane were used. Toner J was obtained by adding the specific surface area coverage to 80% and 20%, respectively.
The toner J and the carrier C were blended so that the toner concentration was 8 parts by weight of the carrier, and the developer J was prepared by uniformly stirring and mixing with a Nauta mixer.

(11) Preparation method of developer K For 100 parts by weight of toner particles prepared in the same manner as toner B, silica particles having primary particle sizes of 12 nm and 200 nm hydrophobized with dimethyl silicone oil and 3-aminopropyltrimethoxysilane were used. Toner K was obtained by adding the specific surface area coverage to 80% and 20%, respectively.
The toner K and the carrier C were blended so that the toner concentration was 8 parts by weight of the carrier, and the developer K was prepared by uniformly stirring and mixing with a Nauta mixer.

(12) Preparation Method of Developer L For 100 parts by weight of toner particles prepared in the same manner as toner A, silica particles having primary particle sizes of 20 nm and 100 nm hydrophobized with dimethyl silicone oil and 3-aminopropyltrimethoxysilane were used. Toner L was obtained by adding the specific surface area coverage to 80% and 20%, respectively.
This toner L and carrier A were blended so that the toner concentration was 8 parts by weight of the carrier, and the developer L was prepared by uniformly stirring and mixing with a nauter mixer.

(13) Preparation method of developer M For 100 parts by weight of toner particles prepared in the same manner as toner A, silica particles having primary particle sizes of 12 nm and 100 nm hydrophobized with dimethyl silicone oil and 3-aminopropyltrimethoxysilane were used. Toner M was obtained by adding the specific surface area coverage to 80% and 20%, respectively.
The toner M and the carrier A were blended so that the toner concentration was 8 parts by weight of the carrier, and the developer M was prepared by uniformly stirring and mixing with a Nauta mixer.

(14) Preparation method of developer N For 100 parts by weight of toner particles prepared in the same manner as toner A, silica particles having primary particle sizes of 30 nm and 300 nm hydrophobized with dimethyl silicone oil and 3-aminopropyltrimethoxysilane were used. Toner N was obtained by adding the specific surface area coverage to 80% and 20%, respectively.
This toner N and carrier A were blended so that the toner concentration would be 8 parts by weight of the carrier, and developer N was prepared by uniformly stirring and mixing with a Nauta mixer.

(15) Preparation method of developer O For 100 parts by weight of toner particles prepared in the same manner as toner B, silica particles having primary particle sizes of 7 nm and 40 nm hydrophobized with dimethyl silicone oil and 3-aminopropyltrimethoxysilane were used. Toner O was obtained by adding the coating ratio in terms of specific surface area to 80% and 20%, respectively.
The toner O and the carrier A were blended so that the toner concentration was 8 parts by weight of the carrier, and the developer O was prepared by uniformly stirring and mixing with a Nauta mixer.

(16) Preparation method of developer P For 100 parts by weight of toner particles prepared in the same manner as toner B, silica particles having primary particle sizes of 12 nm and 150 nm hydrophobized with dimethyl silicone oil and 3-aminopropyltrimethoxysilane were used. Toner P was obtained by adding the coating ratio in terms of specific surface area to 80% and 20%, respectively.
This toner P and carrier A were blended so that the toner concentration would be 8 parts by weight of the carrier, and the developer P was prepared by uniformly stirring and mixing with a Nauta mixer.

4). Vickers hardness measurement
The toner melted in a 20 mm diameter mold and a hardened coating material sample were molded to a thickness of 5 mm using a dynamic ultra-micro hardness meter DUH-W201 manufactured by Shimadzu Corporation, and the Vickers indenter was held for 15 seconds under a load of 10 g. The Vickers hardness was determined from the indentation on the sample. The obtained results are shown in Table 1.

5. Embedding and Desorption Evaluation Using the obtained developer, the embedding of inorganic fine particles on the surface of toner particles and the desorption from the surface of toner particles were conducted using a fluorescent X-ray analyzer RIX200 manufactured by Rigaku Corporation (measurement condition: voltage 60 kV). , Current 30 mA).
First, Si strength was measured for the initial toner particles, and Si strength and Fe strength were measured for the initial carrier surface.
Next, the amount of hydrophobic silica present on the surface of the toner particles was evaluated by measuring the Si strength of the toner particles after 50,000 sheets of ISO 2% intermittent printing were performed.
Further, the Si strength and Fe strength were measured on the carrier surface after carrying out 200,000 sheets of ISO 2% intermittent printing, and the abundance of hydrophobic silica and iron on the carrier surface was evaluated.
By combining the results obtained from these two types of measurements, the removal or embedding of inorganic fine particles from the toner particle surface was evaluated. The obtained results are shown in Table 1. The measured values shown in Table 1 are expressed as relative values with the measured value of the toner particles in the initial state being 1.

(1) Evaluation of embeddability and detachability The embeddability and detachability were evaluated according to the following criteria. That is, when the fluorescent X-ray intensity ratio of the inorganic fine particles on the toner particle surface is 0.7 or more and the fluorescent X-ray intensity ratio of the inorganic fine particles on the carrier surface is less than 55, ○ (detachability and embeddability) Is defined as a non-problematic level).
Further, the case where the fluorescent X-ray intensity ratio of the inorganic fine particles on the toner particle surface is less than 0.7 and the fluorescent X-ray intensity ratio of the inorganic fine particles on the carrier surface is 55 or more is x (detachability and burying property). Is defined as the level that affects the image.

6). Image Evaluation Image evaluation was performed using the obtained developer. That is, these developers were applied to a color printer FS-C5016N (manufactured by Kyocera Mita Co., Ltd.) to form an image, and ISO 5% continuous 200,000 sheet printing and ISO 2% intermittent 50,000 sheet printing were performed.
Subsequently, each of image density, image fog density, and charging stability was evaluated according to the following criteria.
(1) Image Density Using a Gretag Macbeth spectrophotometer SpectroEye, the image density difference between the printing area and the non-printing area was measured at the time of ISO 5% continuous 200,000 sheet printing and ISO 2% intermittent 50,000 sheet printing.
A: The image density difference is 1.2 or more, and no density defect is observed at all.
A: The image density difference is 1.0 or more and less than 1.2, and the density is slightly poor.
Δ: The image density difference is 0.8 or more and less than 1.0, and the density is poor.
X: The image density difference is less than 0.8, and a remarkable density defect is observed.

(2) Image fog density The density of the non-printing area was measured with a spectrophotometer SpectroEye manufactured by Gretag Macbeth Co., Ltd., when 200,000 sheets of ISO 5% continuous printing and 50,000 sheets of ISO 2% intermittent printing were printed.
(Double-circle): The density of a non-printing area | region is 0.008 or less, and a fogging defect is not observed at all.
○: The density of the non-printing area is 0.008 or more and less than 0.010, and the fogging defect is hardly observed.
(Triangle | delta): Although the density | concentration of a non-printing area is 0.010 or more and less than 0.012, a fogging defect is observed a little, but there is no problem in practical use.
X: The density of the non-printing area is 0.012 or more, and a remarkable fogging defect is observed.

(3) Charging Stability Measurement was carried out using a 635 mesh (aperture 20 μm) with a q / m meter MODEL 210HS manufactured by Trek Japan.

[Example 1]
The developer A was applied to a color printer FS-C5016N (manufactured by Kyocera Mita Corporation) to form an image, and the above-described Vickers hardness measurement, embedded / detached evaluation, and image evaluation were performed. The obtained results are shown in Table 1.

[Examples 2 to 11]
In Examples 2 to 11, the above-described evaluation was performed in the same manner as in Example 1 except that the toners B to K were used. The obtained results are shown in Table 1.

[Comparative Examples 1-5]
In Comparative Examples 1 to 5, the above-described evaluation was performed in the same manner as in Example 1 except that the toners L to P were used. The obtained results are shown in Table 1.

As can be understood from the results shown in Table 1, in Examples 1 to 11, a developer having good embedding evaluation and detachment evaluation was used, and thus a good image was obtained in the image evaluation.
On the other hand, in Comparative Example 1, Comparative Example 2, and Comparative Example 4, a defect was observed in the image density evaluation. This is because the fluorescent X-ray intensity of the inorganic particles on the toner surface is below a predetermined value, the amount of inorganic fine particles embedded in the toner is large, and the spacer effect of the toner due to the inorganic fine particles is reduced. It is thought that it was because of.
In Comparative Example 3 and Comparative Example 5, a defect was observed in the image density evaluation. This is presumably because the inorganic X-ray intensity of the inorganic particles on the carrier surface is not less than a predetermined value, so that the inorganic fine particles are detached, the carrier is contaminated, and the charging ability of the toner is lowered.

Further, the three values of Vickers hardness (HVt) of the toner particles, Vickers hardness (HVc) of the coating resin, and average primary particle size (d) of the inorganic fine particles in Examples 1 to 11 and Comparative Examples 1 to 6 described above, Table 2 shows the relationship with Equation (1).
Here, the estimated value in Table 2 is an inorganic value calculated by substituting the Vickers hardness (HVt) value of the toner particles and the Vickers hardness (HVc) value of the coating resin into the formula (1). It means the range of the average primary particle size (d) of the fine particles.
Further, the comprehensive evaluation in Table 2 is an evaluation in which the measured value of the average primary particle size (d) of the inorganic fine particles is within the range of the estimated value described above, and the case where the measured value is outside is evaluated as x. Means the result.
That is, as understood from the results shown in Table 2, in Examples 1 to 11, the condition of Formula (1) is satisfied, and in Comparative Examples 1 to 5, the condition of Formula (1) is satisfied. I understand that there is no.

4 is a graph showing a range that satisfies the relationship between the Vickers hardness of toner particles, the Vickers hardness of carrier particles, and the average primary particle size of inorganic fine particles in the present invention. It is a figure provided in order to demonstrate the hybrid developing device in this invention. FIG. 3 is a diagram for explaining an image forming apparatus according to the present invention.

Explanation of symbols

20: Image forming device, 21: Endless belt (conveyor belt), 22: Paper feed cassette, 23: Fixing device, 24a: Developing device for black, 24b: Developing device for yellow, 24c: Developing device for cyan, 24d: Development device for magenta, 25a to 25d: supply roller (magnetic roller), 26a to 26d: development roller, 27a to 27d: photosensitive drum, 28a to 28d: charger, 29a to 29d: exposure device, 30a to 30d: transfer Apparatus 31a: rotating sleeve 31b: fixed magnet 32: developing device 33a: direct current (DC) bias power source 33b: alternating current (AC) bias power source 34: direct current (DC) bias power source 35: paddle mixer 36 : Stirring mixer, 37: Partition plate, 38: Cutting blade (layer thickness regulating blade), 100: Hybrid developing device

Claims (4)

A developer transport body for charging the developer while magnetically holding it, a developing roll for transferring the developer from the transport body to form a thin layer of toner on the surface, and a developing bias for the developing roll A developer for use in a hybrid developing device comprising a developing device for applying and developing a latent image on a latent image carrier,
The developer includes at least toner particles externally treated with inorganic fine particles and a carrier whose surface is coated with a resin film, and has the following configurations (a) to (c). Developer.
(A) Vickers hardness (HVt) as a surface hardness of toner particles is a value within a range of 12 to 18 (kg / mm ² ).
(B) Vickers hardness (HVc) as the surface hardness of the resin coating is a value of 30 (kg / mm ² ) or less.
(C) The Vickers hardness (HVt) of the toner particles, the Vickers hardness (HVc) of the resin coating, and the average primary particle diameter d (nm) of the inorganic fine particles satisfy the following relational expression (1).
3 (22−HVt) ≦ d ≦ (5/3) (HVc) (22−HVt) (1)   2. The developer according to claim 1, wherein the inorganic fine particles include first inorganic fine particles having an average primary particle size of 30 nm or less and second inorganic fine particles having an average primary particle size of 40 nm or more. .   3. The developer according to claim 1, wherein the inorganic fine particles are ones of silica, titanium oxide, aluminum oxide, magnetite, and zinc oxide used alone or in combination of two or more.   An image forming method using the developer according to claim 1.

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