JP5352614B2 - Method for producing carrier core material for electrophotographic developer, carrier core material for electrophotographic developer, carrier for electrophotographic developer, and electrophotographic developer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a production method of a carrier core material for an electrophotographic developer, the core material which has favorable characteristics and can be inexpensively produced. <P>SOLUTION: A production method of a carrier core material for an electrophotographic developer aims to produce a carrier core material for an electrophotographic developer, the material comprising, as a main component, a core composition expressed by general formula of Z<SB POS="POST">x</SB>Ca<SB POS="POST">y</SB>Fe<SB POS="POST">3-x-y</SB>O<SB POS="POST">4</SB>(where x and y satisfy 0&le;x&le;1 and 0&lt;y&le;1, and Z represents at least one metal selected from the group consisting of Mg, Mn, Ti, Cu, Zn, Sr and Ni). The method includes: a mixing step of mixing a raw material containing iron and a raw material containing calcium; a granulation step of granulating the obtained mixture after the mixing step; and a calcination step of calcining the powdery material granulated in the granulation step at a predetermined temperature to form a magnetic phase. The raw material containing calcium to be mixed in the mixing step contains a water-soluble calcium salt. <P>COPYRIGHT: (C)2013,JPO&amp;INPIT

Description

  The present invention relates to a method for producing a carrier core material for an electrophotographic developer (hereinafter sometimes simply referred to as “carrier core material”), a carrier core material for an electrophotographic developer, and a carrier for an electrophotographic developer (hereinafter simply referred to as “a carrier core material”). And electrophotographic developer (hereinafter sometimes simply referred to as “developer”), and in particular, an electrophotographic developer used in a copying machine, an MFP (Multifunctional Printer), and the like. The present invention relates to an electrophotographic developer carrier core material, a method for producing the same, an electrophotographic developer carrier provided in the electrophotographic developer, and an electrophotographic developer.

  In a copying machine, MFP, etc., as a dry development method in electrophotography, a one-component developer using only toner as a component of developer and a two-component developer using toner and carrier as components of developer are provided. is there. In any of the development methods, toner charged to a predetermined charge amount is supplied to the photoreceptor. Then, the electrostatic latent image formed on the photosensitive member is visualized with toner and transferred to a sheet. Thereafter, the visible image with toner is fixed on the paper to obtain a desired image.

  Here, the development in the two-component developer will be briefly described. A predetermined amount of toner and a predetermined amount of carrier are accommodated in the developing device. The developing device includes a rotatable magnet roller in which a plurality of S poles and N poles are alternately provided in the circumferential direction, and a stirring roller that stirs and mixes the toner and the carrier in the developing device. A carrier made of magnetic powder is carried by a magnet roller. A linear magnetic brush made of carrier particles is formed by the magnetic force of the magnet roller. A plurality of toner particles adhere to the surface of the carrier particles by frictional charging by stirring. Toner is supplied to the surface of the photoconductor by rotating the magnet roller so that the magnetic brush is applied to the photoconductor. In a two-component developer, development is performed in this way.

  As for the toner, the toner in the developing device is sequentially consumed by fixing to the paper, so new toner corresponding to the consumed amount is supplied from time to time to the developing device from the toner hopper attached to the developing device. The On the other hand, the carrier is not consumed by development and is used as it is until the end of its life. The carrier which is a constituent material of the two-component developer includes a toner charging function and an insulating property for efficiently charging the toner by frictional charging by stirring, a toner transporting ability to appropriately transport and supply the toner to the photoreceptor, etc. Various functions are required.

  In recent years, the above-described carrier is composed of a carrier core material that constitutes a core, that is, a core portion, and a coating resin that is provided so as to cover the surface of the carrier core material.

Here, the technique regarding the magnetic body particle | grains of a carrier is disclosed by the patent 3641728 (patent document 1). According to Patent Document 1, it is described that there is a metal compound such as CaO (calcium oxide) or CaCO ₃ (calcium carbonate) as a component for controlling the electric resistance and charge amount of the magnetic particles of the carrier or as a sintering accelerator. Yes.

Japanese Patent No. 3641728

  The carrier core material is desired to have good electrical characteristics, specifically, for example, a high charge amount of the carrier core material itself.

  In recent years, there is a tendency that it is particularly strongly desired to increase the charging ability of the carrier core material itself, specifically, the charge amount of the carrier core material. In general, the carrier core material is used by coating the surface with a coating resin from the viewpoint of improving the electrical characteristics thereof. Here, a part of the coating resin may be peeled off due to stress caused by stirring in the developing device, and the surface of the carrier core material may be exposed. In such a situation, there is a strong demand for charging ability by friction between the exposed surface of the carrier core material itself and the toner. Of course, it is preferable that other characteristics such as magnetic characteristics are also favorable.

  The carrier core material is coated with the coating resin as described above, and it is desired to reduce the amount of the coating resin to be coated. That is, when manufacturing a carrier having equivalent performance, if the coating resin for coating the carrier core material is small, it is possible to reduce the manufacturing cost. Furthermore, in addition to reducing the overall amount of coating resin, the physical effects due to the coating conditions, that is, the labor required to examine the coating conditions of the coating resin on the carrier core material, and errors in the coating conditions, etc. Can also be reduced.

  An object of the present invention is to provide a method for producing a carrier core material for an electrophotographic developer that has good characteristics and can be produced at low cost.

  Another object of the present invention is to provide a carrier core material for an electrophotographic developer that has good characteristics and can be produced at low cost.

  Still another object of the present invention is to provide a carrier for an electrophotographic developer that has good characteristics and can be produced at low cost.

  Still another object of the present invention is to provide an electrophotographic developer that has high image quality and can be produced at low cost.

In order to improve the characteristics of the carrier core material, specifically, the charging performance, which is one of the electrical characteristics required for the carrier core material, the inventors of the present application have improved the frictional charging ability of the carrier core material. In order to achieve this, it was considered to add calcium (Ca), which is a metal element, as a core component of the carrier core material. Here, this inventor considered that it was necessary to consider the influence on the surface property of the carrier core material manufactured about calcium contained as a constituent material of a carrier core material. That is, the inventors of the present invention have the general formula: Z _x Ca _y Fe _3-xy O ₄ (0 ≦ x ≦ 1, 0 <y ≦ 1, where Z is Mg, Mn, Ti, Cu, Zn , At least one metal selected from the group consisting of Sr and Ni), the carrier core material having a core composition as a main component, good surface properties, specifically, the degree of unevenness on the surface of the carrier core material It was considered that the amount of the coating resin can be reduced if is low. Here, in the carrier core material obtained through the granulation step and the firing step, it was considered to realize a surface property with less unevenness during the production, specifically, good grain growth of the crystal at the time of firing. .

That is, the method of manufacturing an electrophotographic developer carrier core material according to the present invention have the general _{formula: Z x Ca y Fe 3-} x-y O 4 (0 ≦ x ≦ 1,0 <y ≦ 1, however, Z Is a method for producing a carrier core material for an electrophotographic developer having as a main component a core composition represented by at least one metal selected from the group consisting of Mg, Mn, Ti, Cu, Zn, Sr, and Ni). A mixing step of mixing a raw material containing iron and a raw material containing calcium, a granulation step of granulating the mixed mixture after the mixing step, and a powdery material granulated by the granulation step And a firing step of forming a magnetic phase by firing at a temperature of. Here, the raw material containing calcium mixed in the mixing step is a raw material containing a water-soluble calcium salt.

About the carrier core material manufactured by such a manufacturing method of the carrier core material for electrophotographic developer, since calcium is added as a core composition, charging performance which is one of the characteristics required for the carrier core material Can be high. Here, when using a raw material containing calcium, it is a raw material containing a water-soluble calcium salt, not CaO or CaCO ₃ insoluble in water, which is generally used as an inexpensive material disclosed in Patent Document 1. At the time of manufacture, the degree of unevenness on the surface of the carrier core material can be reduced, and a relatively smooth surface can be obtained. Then, on the surface of the carrier core material, the resin necessary for filling the recessed portion is not required in the subsequent coating with the coating resin, and the amount of the coating resin can be greatly reduced. Also, a high level can be maintained in the magnetic characteristics and the like. Therefore, according to such a method for producing a carrier core material for an electrophotographic developer, a carrier core material for an electrophotographic developer having good characteristics can be produced at low cost.

In general _{formula: Z x Ca y Fe 3-} x-y O 4 (0 ≦ x ≦ 1,0 <y ≦ 1, however, Z is, Mg, Mn, Ti, Cu , Zn, Sr, of Ni A carrier core material for an electrophotographic developer whose main component is a core composition represented by at least one metal selected from the group) When x = 0, iron and calcium except for so-called inevitable impurities Is included as a core composition.

Preferably, the substance excluding calcium in the water-soluble calcium salt is composed of a reducing substance. By comprising in this way, the carrier core material whose surface unevenness degree is lower can be manufactured.

As a further preferred embodiment, the water-soluble calcium salt contains Ca (CH ₃ COO) ₂ (calcium acetate). Such a calcium salt can be obtained at a relatively low cost and has good handleability, so that the efficiency during production can be further improved.

In another aspect of the present invention, the electrophotographic developer carrier core material, the general _{formula: Z x Ca y Fe 3-} x-y O 4 (0 ≦ x ≦ 1,0 <y ≦ 1, however, Z is , Mg, Mn, Ti, Cu, Zn, Sr, Ni, and a carrier core material for an electrophotographic developer having a core composition as a main component represented by a core composition represented by: And a raw material containing calcium and a calcium containing raw material are mixed to granulate the mixture, and the granulated particles are fired at a predetermined temperature to form a magnetic phase. Here, the raw material containing calcium is a raw material containing a water-soluble calcium salt.

  Such a carrier core material for an electrophotographic developer has good characteristics and can be manufactured at low cost.

The carrier core material for an electrophotographic developer according to the present invention has a general formula: Z _x Ca _y Fe _3-xy O ₄ (0 ≦ x ≦ 1, 0 <y ≦ 1, where Z is Mg , At least one metal selected from the group consisting of Mn, Ti, Cu, Zn, Sr, and Ni), and a carrier core material for an electrophotographic developer having a core composition as a main component. When the particle surface of the carrier core material for an agent is observed with a laser microscope at a magnification of 500 times, the length in the X direction in the cross-sectional curved surface is L, the length in the Y direction in the cross-sectional curved surface is M, and the cross section Assuming that the curved surface is f (x, y), the value of the surface property SRa represented by the formula 1 is 0.800 or less.

  Preferably, the core charge amount of the carrier core material for an electrophotographic developer is 10 μC / g or more.

  In still another aspect of the present invention, an electrophotographic developer carrier is an electrophotographic developer carrier used for an electrophotographic developer, and the carrier core material for an electrophotographic developer described above, And a resin that covers the surface of the carrier core material for the electrophotographic developer.

  Such a carrier for an electrophotographic developer has good characteristics and can be produced at low cost.

  In still another aspect of the present invention, the electrophotographic developer is an electrophotographic developer used for electrophotographic development, and the triboelectric charging between the above-described electrophotographic developer carrier and the electrophotographic developer carrier. And a toner capable of being charged in electrophotography.

  Since such an electrophotographic developer includes the electrophotographic developer carrier having the above-described configuration, the electrophotographic developer has high image quality and can be manufactured at low cost.

  According to such a method for producing a carrier core material for electrophotographic developer, a carrier core material for electrophotographic developer having good characteristics can be produced at low cost.

  Further, such a carrier core material for an electrophotographic developer has good characteristics and can be produced at low cost.

  Moreover, such a carrier for an electrophotographic developer has good characteristics and can be produced at low cost.

  Further, such an electrophotographic developer has high image quality and can be manufactured at low cost.

It is a flowchart which shows a typical process in the manufacturing method which manufactures the carrier core material which concerns on one Embodiment of this invention. 4 is an electron micrograph showing the appearance of the surface of a carrier core material according to Reference Example 1. 6 is an electron micrograph showing the appearance of the surface of a carrier core material according to Comparative Example 3. 4 is an electron micrograph showing the appearance of the surface of a carrier core material according to Example 3. FIG. FIG. 3 is a schematic view showing a crystal grain boundary portion with lines in the appearance of the surface of the carrier core material according to Reference Example 1 shown in FIG. 2. It is the schematic which showed the part of the crystal grain boundary with the line | wire in the external appearance of the surface of the carrier core material which concerns on the comparative example 3 shown in FIG. FIG. 5 is a schematic view showing a crystal grain boundary portion with lines in the appearance of the surface of the carrier core material according to Example 3 shown in FIG. 4. In the carrier core material which concerns on the comparative example 3, it is the schematic of the granular powder in the formation process of a magnetic phase. In the carrier core material which concerns on Example 3, it is the schematic of the granular powder in the formation process of a magnetic phase. 6 is an electron micrograph showing an appearance of a carrier surface after resin coating according to Comparative Example 3. FIG. 4 is an electron micrograph showing the appearance of a carrier surface after resin coating according to Example 3. FIG. In the external appearance of the surface of the carrier core material which concerns on the comparative example 3 shown in FIG. 10, it is the schematic which showed the approximate boundary part of the application | coating area | region of coating resin with the line. FIG. 12 is a schematic view showing a rough boundary portion of a coating resin application region with a line in the appearance of the surface of the carrier core material according to Example 3 shown in FIG. 11.

  Embodiments of the present invention will be described below with reference to the drawings. First, a carrier core material according to an embodiment of the present invention will be described. About the carrier core material which concerns on one Embodiment of this invention, the external shape is a substantially spherical shape. The particle diameter of the carrier core material according to one embodiment of the present invention is about 38 μm and has an appropriate particle size distribution. That is, the above-mentioned particle size means a volume average particle size. The particle size and particle size distribution are arbitrarily set depending on required developer characteristics, yield in the manufacturing process, and the like. On the surface of the carrier core material, minute irregularities formed mainly in the baking step described later are formed. This unevenness degree will be described later.

  The carrier according to one embodiment of the present invention also has a substantially spherical shape as in the carrier core material. The carrier is obtained by thinly coating the surface of the carrier core material with a resin, that is, the particle diameter of the carrier is almost the same as that of the carrier core material.

  The developer according to one embodiment of the present invention is composed of the above-described carrier and toner. The outer shape of the toner is also substantially spherical. The toner is mainly composed of a styrene acrylic resin or a polyester resin, and contains a predetermined amount of pigment, wax or the like. Such a toner is manufactured by, for example, a pulverization method or a polymerization method. For example, a toner having a particle diameter of about 5 μm, which is about 1/7 of the particle diameter of the carrier, is used. Further, the mixing ratio of the toner and the carrier is also arbitrarily set according to the required developer characteristics and the like. Such a developer is produced by mixing a predetermined amount of carrier and toner with an appropriate mixer.

Next, the manufacturing method which manufactures the carrier core material which concerns on one Embodiment of this invention is demonstrated. FIG. 1 is a flowchart showing typical steps in a manufacturing method for manufacturing a carrier core material according to an embodiment of the present invention. A method for manufacturing a carrier core material according to an embodiment of the present invention will be described below with reference to FIG. For the carrier core material, the above general formula: Z _x Ca _y Fe _3-xy O ₄ (0 ≦ x ≦ 1, 0 <y ≦ 1, where Z is Mg, Mn, Ti, Cu , Zn, Sr, Ni, and at least one metal selected from the group consisting of a core composition as a main component, x = 0, that is, the general formula: Ca _y Fe _3-y O What is represented by ₄ will be mainly described.

  First, a raw material containing iron and a raw material containing calcium are prepared. And the prepared raw material is mix | blended with a suitable compounding ratio according to the characteristic requested | required, and this is mixed (FIG. 1 (A)). Here, an appropriate blending ratio is a blending ratio that the finally obtained carrier core material contains.

About the raw material containing the iron which comprises the carrier core material which concerns on one Embodiment of this invention, what is necessary is just metallic iron or its oxide. Specifically, Fe ₂ O ₃ , Fe ₃ O ₄ , Fe, and the like that exist stably at normal temperature and pressure are preferably used.

Here, the raw material containing water-soluble calcium salt is used about the raw material containing calcium. By carrying out like this, the carrier core material with few unevenness | corrugations can be obtained on the surface. In this case, it is good to use what is comprised with the substance which has a reducing property as a substance except calcium in water-soluble calcium salt . By carrying out like this, the carrier core material with few unevenness | corrugations can be obtained on the surface. Specifically, in this case, a raw material containing Ca (CH ₃ COO) ₂ (calcium acetate) is used.

  About the raw material containing calcium, it mixes as a solution state. By doing in this way, generation | occurrence | production of the aggregation of the raw material containing the calcium to add can be suppressed efficiently, and the dispersibility of the calcium in a carrier core material can be improved more reliably.

The raw materials (iron raw material, calcium raw material) may be used as raw materials by calcining and pulverizing raw materials obtained by mixing the respective raw materials (iron raw material and calcium raw material) so as to have a desired composition. Here, the carrier core material, the general _{formula: Z x Ca y Fe 3-} x-y O 4 (0 ≦ x ≦ 1,0 <y ≦ 1, however, Z is, Mg, Mn, Ti, Cu, You may comprise so that the core composition represented by the at least 1 type of metal selected from the group which consists of Zn, Sr, and Ni) may be made into a main component.

  Next, the mixed raw material is slurried (FIG. 1B). That is, these raw materials are weighed according to the target composition of the carrier core material and mixed to obtain a slurry raw material.

  In the manufacturing process for manufacturing the carrier core material according to the present invention, a reducing agent may be further added to the slurry raw material described above in order to advance the reduction reaction in a part of the baking process described later. As the reducing agent, carbon powder, polycarboxylic acid organic substance, polyacrylic acid organic substance, maleic acid, acetic acid, polyvinyl alcohol (PVA (polyvinyl alcohol)) organic substance, and a mixture thereof are preferably used.

  Water is added to the slurry raw material described above and mixed and stirred, so that the solid concentration is 40% by weight or more, preferably 50% by weight or more. If the solid content concentration of the slurry raw material is 50% by weight or more, it is preferable because the strength of the granulated pellet can be maintained.

  Next, the slurryed raw material is granulated (FIG. 1C). Granulation of the slurry obtained by mixing and stirring is performed using a spray dryer. In addition, it is also preferable to further wet-grind the slurry before granulation.

  The atmospheric temperature during spray drying may be about 100 to 300 ° C. Thereby, the granulated powder whose particle diameter is 10-200 micrometers can be obtained in general. The obtained granulated powder is preferably adjusted for particle size at this point in consideration of the final particle size of the product by removing coarse particles and fine powder using a vibration sieve or the like.

Thereafter, the granulated product is fired (FIG. 1D). Specifically, the obtained granulated powder is put into a furnace heated to about 900 to 1500 ° C., held and fired for 1 to 24 hours, and a desired fired product is generated. At this time, the oxygen concentration in the firing furnace may be any condition that allows the ferritization reaction to proceed. Specifically, at 1200 ° C., the oxygen concentration of the introduced gas is set to be 10 ⁻⁷ % to 3%. Adjust and fire under flow conditions.

  Moreover, you may control the reducing atmosphere required for ferritization by adjustment of a previous reducing agent. However, from the viewpoint of obtaining a reaction rate that can ensure sufficient productivity during industrialization, a temperature of 900 ° C. or higher is preferable. On the other hand, if the firing temperature is 1500 ° C. or lower, the particles are not excessively sintered, and a fired product can be obtained in the form of powder.

  It is desirable to further adjust the particle size of the obtained fired product at this stage. For example, the fired product is coarsely pulverized with a hammer mill or the like. That is, pulverization is performed on the baked granular material (FIG. 1E). After that, classification is performed using a vibrating screen. That is, classification is performed on the pulverized granular material (FIG. 1 (F)). By carrying out like this, the particle | grains of the carrier core material with a desired particle size can be obtained.

Thus, the carrier core material according to one embodiment of the present invention is manufactured. That is, the method for producing a carrier core material for an electrophotographic developer according to an embodiment of the present invention has a general formula: Z _x Ca _y Fe _3-xy O ₄ (0 ≦ x ≦ 1, 0 <y ≦ 1 However, Z is at least one metal selected from the group consisting of Mg, Mn, Ti, Cu, Zn, Sr, and Ni). A mixing step of mixing a raw material containing iron and a raw material containing calcium, a granulating step of granulating the mixed mixture after the mixing step, and a powder granulated by the granulating step And a firing step of firing the material at a predetermined temperature to form a magnetic phase. Here, the raw material containing calcium mixed in the mixing step is a raw material containing a water-soluble calcium salt.

About the carrier core material manufactured by such a manufacturing method of the carrier core material for electrophotographic developer, since calcium is added as a core composition, charging performance which is one of the characteristics required for the carrier core material Can be high. Here, when using a raw material containing calcium, it is a raw material containing a water-soluble calcium salt, not CaO or CaCO ₃ insoluble in water, which is generally used as an inexpensive material disclosed in Patent Document 1. At the time of manufacture, the degree of unevenness on the surface of the carrier core material can be lowered to obtain a relatively smooth surface. Then, on the surface of the carrier core material, the resin necessary for filling the recessed portion is not required in the subsequent coating with the coating resin, and the amount of the coating resin can be greatly reduced. This will be described later. Also, a high level can be maintained in the magnetic characteristics and the like. Therefore, according to such a method for producing a carrier core material for an electrophotographic developer, a carrier core material for an electrophotographic developer having good characteristics can be produced at low cost.

In addition, the carrier core material for an electrophotographic developer according to one embodiment of the present invention has a general formula: Z _x Ca _y Fe _3-xy O ₄ (0 ≦ x ≦ 1, 0 <y ≦ 1, Z is a carrier core material for an electrophotographic developer whose main component is a core composition represented by (at least one metal selected from the group consisting of Mg, Mn, Ti, Cu, Zn, Sr, Ni). A raw material containing iron and a raw material containing calcium are mixed to granulate the mixture, and the granulated granule is fired at a predetermined temperature to form a magnetic phase. Here, the raw material containing calcium is a raw material containing a water-soluble calcium salt.

  Such a carrier core material for an electrophotographic developer has good characteristics and can be manufactured at low cost.

  Next, the carrier core material obtained in this way is coated with a resin (FIG. 1 (G)). Specifically, the obtained carrier core material according to the present invention is covered with a silicone resin, an acrylic resin, or the like. In this way, an electrophotographic developer carrier according to an embodiment of the present invention is obtained. A coating method such as silicone resin or acrylic resin can be performed by a known method. That is, an electrophotographic developer carrier according to an embodiment of the present invention is an electrophotographic developer carrier used for an electrophotographic developer, and includes the above-described carrier core material for an electrophotographic developer, and electrophotography. And a resin that covers the surface of the carrier core material for developer. Such a carrier for an electrophotographic developer has good characteristics and can be produced at low cost.

  Next, the carrier and toner thus obtained are mixed by a predetermined amount (FIG. 1 (H)). Specifically, the carrier for an electrophotographic developer according to one embodiment of the present invention obtained by the above-described manufacturing method is mixed with an appropriate known toner. Thus, the electrophotographic developer according to one embodiment of the present invention can be obtained. For the mixing, for example, an arbitrary mixer such as a ball mill is used. An electrophotographic developer according to an embodiment of the present invention is an electrophotographic developer used for electrophotographic development, and is obtained by frictional charging between the above-described electrophotographic developer carrier and the electrophotographic developer carrier. And a toner capable of being charged in electrophotography. Since such an electrophotographic developer includes the electrophotographic developer carrier having the above-described configuration, the electrophotographic developer has high image quality and can be manufactured at low cost.

Example 1
74 g of calcium acetate monohydrate (Ca (CH ₃ COO) ₂ .H ₂ O) is dispersed in 3 kg of water to form an aqueous solution, 10 kg of Fe ₂ O ₃ is added, and an ammonium polycarboxylate dispersant is added as a dispersant. 200 g and 105 g of carbon black as a reducing agent were added to form a mixture. As a result of measuring the solid content concentration at this time, it was 75% by weight. This mixture was pulverized by a wet bead mill (media diameter 2 mm) to obtain a mixed slurry.

  This slurry was sprayed into hot air at about 130 ° C. with a spray dryer to obtain dry granulated powder. At this time, granulated powder other than the target particle size distribution was removed by sieving. This granulated powder was put into an electric furnace and fired at 1130 ° C. for 3 hours. At this time, the electric furnace was flowed to an electric furnace whose atmosphere was adjusted so that the oxygen concentration was 0.1% or less. The obtained fired product was classified using a sieve after pulverization to an average particle size of 38 μm. Thus, the carrier core material according to Example 1 was obtained.

Table 1 shows the magnetic characteristics and electrical characteristics of the obtained carrier core material. Note that the amount y described in Table 1, the general formula The composition of the carrier core material as described above: when expressed in _{Ca y Fe 3-y O 4} , analytical methods indicating the obtained carrier core material below It is the result obtained by measuring with. Hereinafter, the value of y is the same in the second and subsequent examples. In this embodiment, x = 0, that is, the general formula does not include Mn or the like as Z.

(Ca analysis)
The Ca content of the carrier core material was analyzed by the following method. The carrier core material according to the present invention was dissolved in an acid solution, and quantitative analysis was performed by ICP. The Ca content of the carrier core material described in the present invention is the amount of Ca obtained by this quantitative analysis by ICP.

(Evaluation of magnetic force)
Moreover, about the measurement of the magnetization which shows the magnetic characteristic in Table 1, the magnetic susceptibility was measured using VSM (the Toei industry Co., Ltd. make, VSM-P7). Here, in Table 1, “σ _{1k (1000)} ” is the magnetization when the external magnetic field is 1 k (1000) Oe, “σs” is the saturation magnetization, and “σr” is the residual Magnetization.

(Calculation of average particle size)
In addition, about an average particle diameter, the center particle diameter in volume particle size distribution is meant, The Nikkiso Co., Ltd. microtrack and Model9320-X100 are used for the measurement.

(Evaluation of electrical characteristics)
The core charge amount as an electrical characteristic in Table 1 is the charge amount of the core, that is, the carrier core material. Here, the measurement of the charge amount will be described. 9.5 g of carrier core material and 0.5 g of commercially available full-color toner are put into a 100 ml stoppered glass bottle and left to stand for 12 hours in an environment of 25 ° C. and 50% relative humidity to adjust the humidity. The conditioned carrier core material and toner are shaken for 30 minutes with a shaker and mixed. Here, the shaker was performed at a rate of 200 ° / min and an angle of 60 ° using a NEW-YS type manufactured by Yayoi Co., Ltd. 500 mg of the mixed carrier core material and toner were weighed, and the charge amount was measured with a charge amount measuring device. In this embodiment, STC-1-C1 type manufactured by Nippon Piotech Co., Ltd. was used, suction pressure was 5.0 kPa, and a mesh for suction was performed with 795 mesh manufactured by SUS. Two measurements were performed on the same sample, and the average of these values was used as the charge amount of each core. Regarding the calculation formula of the core charge amount, core charge amount (μC (Coulomb) / g) = actual charge (nC) × 10 ³ × coefficient (1.00083 × 10 ⁻³ ) ÷ toner weight (weight before suction (g) -Weight after suction (g)).

(Example 2)
A carrier core material according to Example 2 was obtained in the same manner as in Example 1 except that the amount of calcium acetate monohydrate added was 149 g. Table 1 shows the magnetic characteristics and electrical characteristics of the obtained carrier core material.

(Example 3)
A carrier core material according to Example 3 was obtained in the same manner as in Example 1 except that the amount of calcium acetate monohydrate added was 223 g. Table 1 shows the magnetic characteristics and electrical characteristics of the obtained carrier core material.

Example 4
About the calcium raw material to be added, as a calcium nitrate aqueous solution (containing 9.2% by weight of Ca), the addition amount was 182 g, and the amount of carbon black to be added was 118 g. A carrier core material according to Example 4 was obtained. Table 1 shows the magnetic characteristics and electrical characteristics of the obtained carrier core material.

(Example 5)
A carrier core material according to Example 5 was obtained in the same manner as in Example 4 except that the addition amount of the calcium nitrate aqueous solution was 363 g and the addition amount of carbon black was 130 g. Table 1 shows the magnetic characteristics and electrical characteristics of the obtained carrier core material.

(Example 6)
A carrier core material according to Example 6 was obtained in the same manner as in Example 4 except that the addition amount of the aqueous calcium nitrate solution was 545 g and the addition amount of carbon black was 143 g. Table 1 shows the magnetic characteristics and electrical characteristics of the obtained carrier core material.

(Example 7)
Example 7 is the same as Example 1 except that the amount of calcium acetate monohydrate added is 223 g, Fe ₂ O ₃ is 6.8 kg, and Mn ₃ O ₄ 3.2 kg is further added. A carrier core was obtained. Table 2 shows the magnetic characteristics and electrical characteristics of the obtained carrier core material. In this embodiment, the value of x is approximately 1, and in the general formula, Z is Mn.

(Reference Example 1)
A carrier core material according to Reference Example 1 was obtained in the same manner as in Example 1 except that the calcium raw material was not added. Table 1 shows the magnetic characteristics and electrical characteristics of the obtained carrier core material.

(Comparative Example 1)
The carrier core material according to Comparative Example 1 was obtained in the same manner as in Example 1 except that the calcium raw material to be added was calcium carbonate and the amount added was 42 g. Table 1 shows the magnetic characteristics and electrical characteristics of the obtained carrier core material.

(Comparative Example 2)
A carrier core material according to Comparative Example 2 was obtained in the same manner as Comparative Example 1, except that the amount of calcium carbonate added was 84 g. Table 1 shows the magnetic characteristics and electrical characteristics of the obtained carrier core material.

(Comparative Example 3)
A carrier core material according to Comparative Example 3 was obtained in the same manner as in Comparative Example 1, except that the amount of calcium carbonate added was 125 g. Table 1 shows the magnetic characteristics and electrical characteristics of the obtained carrier core material.

(Reference Example 2)
A carrier core material according to Reference Example 2 was obtained in the same manner as in Example 7 except that the calcium raw material was not added. Table 2 shows the magnetic characteristics and electrical characteristics of the obtained carrier core material. In this embodiment, the value of x is approximately 1, and in the general formula, Z is Mn.

Referring to Tables 1 and 2, regarding the magnetic characteristics, the value of σ ₁₀₀₀ is 59 to 70 Am ² / kg in any of the examples, reference examples, and comparative examples, and σ s indicating saturation magnetization It can be understood that the value of is 80 to 92 Am ² / kg. Also, the value of σr indicating the residual magnetization is 0.9 to 2.6 Am ² / kg, which can be understood to be a relatively low value. In particular, in Examples 1-3 and 7, it is 1.1-1.4 Am < ² > / kg, and is maintaining a considerably low value. If such a carrier core material having a low residual magnetization is used, the magnetic brush can be formed satisfactorily.

  Regarding the electrical characteristics, in Examples 1, 2, and 3, the core charge amounts were 11.7 μC / g, 16.0 μC / g, and 16.4 μC / g, respectively. 10.0 μC / g or more. In Examples 4 to 6, the core charge amounts were 11.7 μC / g, 17.0 μC / g, and 19.2 μC / g, respectively, and in each case, 10.0 μC / g or more. In Example 7, the core charge amount is 24.8 μC / g, which is a considerably high value. That is, when a high charge amount is desired, the structure may include Mn as Z. On the other hand, in the case of the reference example 1 which does not contain Ca, it is 4.4 μC / g, and in the case of the reference example 2, it is 4.5 μC / g. That is, in Examples 1 to 7, high charging performance is maintained.

  Here, the surface of the carrier core material according to the reference example, the example and the comparative example will be examined. FIG. 2 is an electron micrograph showing the appearance of the surface of the carrier core material according to Reference Example 1. FIG. 3 is an electron micrograph showing the appearance of the surface of the carrier core material according to Comparative Example 3. FIG. 4 is an electron micrograph showing the appearance of the surface of the carrier core material according to Example 3. FIG. 5 is a schematic view showing the crystal grain boundary portion with lines in the appearance of the surface of the carrier core material according to Reference Example 1 shown in FIG. FIG. 6 is a schematic view showing the crystal grain boundary portion with lines in the appearance of the surface of the carrier core material according to Comparative Example 3 shown in FIG. FIG. 7 is a schematic view showing the crystal grain boundary portion with lines in the appearance of the surface of the carrier core material according to the third embodiment shown in FIG. 2 to 4 are cases where the image is enlarged 5000 times. 5 to 7 are illustrated based on electron micrographs shown in FIGS. 2 to 4 from the viewpoint of easy understanding.

  2 to 7, Reference Example 1 is a system in which calcium is not added, but the surface 12 of the carrier core material 11 has a relatively high degree of unevenness, and the boundary 12 seen as a crystal grain boundary is present. There are many grains 13, and grains 13 as particles grow moderately. Here, when it sees about the comparative example 3, compared with the reference example 1, the unevenness | corrugation degree of the surface of the carrier core material 14 is still higher. And there are quite a large number of boundaries 15 that are seen as crystal grain boundaries, and the grains 16 hardly grow, and the size remains small. On the other hand, in Example 3, as compared with Reference Example 1, the degree of unevenness on the surface of the carrier core material 17 is low, and there are few boundaries 18 seen as crystal grain boundaries. And it can be grasped that each grain 19 is growing greatly.

  About this, it is guessed that the following phenomenon has occurred. FIG. 8 is a schematic view of the granular material in the magnetic phase formation stage in the carrier core material according to Comparative Example 3. FIG. 9 is a schematic view of the granular material in the magnetic phase formation stage in the carrier core material according to the third embodiment.

First, referring to FIG. 8, in granular powder 21 according to Comparative Example 3, water-insoluble calcium carbonate particles 22 are dispersed and interposed between hematite (Fe ₂ O ₃ ) phases 23. . The intervening calcium carbonate particles 22 are thought to inhibit the growth of grains forming the magnetite phase 24 in the magnetic phase formation process in the firing step. On the other hand, with reference to FIG. 9, about the granular powder 25 which concerns on Example 3, although calcium acetate which is a water-soluble calcium salt is added, since it is water-soluble, it is between hematite phases 26. It is considered that the ions are not dispersed and are present as ions (not shown in FIG. 9) attached to the surface of the hematite phase 26. And in the formation process of the magnetic phase in the firing step, the growth of the grains forming the magnetite phase 27 is not suppressed, but grows large, and as a result, a carrier core material with few crystal grain boundaries and a low degree of surface irregularities is produced. It is thought that it is done.

Of the water-soluble calcium salts, substances other than calcium are used such as reducing substances such as calcium acetate (Ca (CH ₃ COO) ₂ ) and calcium nitrate (Ca (NO ₃ ) ₂ ). However, it is preferably composed of a reducing substance such as calcium acetate. With this configuration, it is presumed that the hematite phase does not remain and the hematite phase does not inhibit the growth of the magnetite phase. In addition, when adding an oxidizing substance such as calcium nitrate (Ca (NO ₃ ) ₂ ), a reducing agent such as carbon black to be added in the mixing step is compared with a reducing substance. It is good to add excessively. The above-described Examples 4 to 6 are configured in this way.

Next, the surface property of the carrier core material will be described. The surface property was measured as follows. First, the surface roughness of the carrier core material was read using a laser microscope, and the surface roughness was analyzed. Specifically, using a laser microscope (NEXT OLS3000, manufactured by OLYMPUS (Olympus) Co., Ltd.), first, an image obtained with a 100 × objective lens is further magnified 5 times by digital zoom, The center was the center of the visual field, and the visual field was 26 μm × 19 μm. At this time, the output of the laser is 100, the capture speed is fast, and the lower limit position and the upper limit position of the capture are set manually at points where the in-focus points disappear in the confocal image. It was. For the analysis of the surface roughness, the entire area of 26 μm × 19 μm taken in was used. The cut-off value λ was 1/10. The minimum height was identified as 10% of Pz in the cross section curve, 10% of Rz in the roughness curve , and 10% of Wz in the undulation curve. Here, the cross-sectional curve is a concavo-convex curve read, a roughness curve is a curve obtained by removing a waviness component longer than the wavelength set as the cut-off value λ from the cross-sectional curve, a waviness curve, Curves obtained by extracting a swell component longer than the wavelength set as the cut-off value λ are shown. Pz represents the maximum height of the cross-sectional curve, Rz represents the maximum height roughness, and Wz represents the maximum height swell. The minimum length was identified as 1% of the reference length. Here, the reference length indicates a 1/3 region at the center of the designated cross section. However, the reference length is equal to the evaluation length in the case of a cross-sectional curve. In addition, about the value of SRa, the value of 20 visual field measurement average is used.

  Regarding the surface property, the value of SRa for Comparative Example 1 is 0.838, the value of SRa for Comparative Example 2 is 0.920, and the value of SRa for Comparative Example 3 is 0.886. If calcium carbonate is added as in Comparative Examples 1 to 3, the degree of unevenness increases and the value increases. Here, for Example 1, the value of SRa is 0.761, for Example 2, the value of SRa is 0.735, and for Example 3, the value of SRa is 0. 724. About Examples 1-3, the value of SRa decreases as the addition amount of calcium acetate, which is a substance in which the salt of the water-soluble calcium salt has reducibility, increases. Also, for Example 4, the SRa value is 0.764, for Example 5, the SRa value is 0.700, and for Example 6, the SRa value is 0.763. It is. Also in Examples 4 to 6, the value of SRa is low, Examples 4 and 6 are equivalent to Example 1, and Example 5 is a very low value. Here, according to the carrier core material of the present invention, the value of the surface property SRa is at least 0.800 or less. That is, the carrier core material according to one embodiment of the present invention has a length in the X direction within a curved cross-section when the particle surface of the carrier core material for an electrophotographic developer is observed with a laser microscope at a magnification of 500 times. Is L, the length in the Y direction in the cross-section curved surface is M, and the cross-section curved surface is f (x, y), the value of the surface property SRa expressed by the formula 1 is 0.800 or less. .

  More specifically, in Examples 1 to 6, the value is smaller than 0.781 shown in Reference Example 1, and the value is 0.780 or less.

  Next, using the obtained carrier core material, a carrier for an electrophotographic developer was prepared and evaluated.

  Here, a method for producing a carrier for an electrophotographic developer will be described. The carrier core material was resin-coated by the following method. A silicone resin (trade name: SR-2411, manufactured by Toray Dow Corning) was dissolved in toluene to prepare a coating resin solution. And it introduce | transduced into the stirrer in the ratio that a coating amount will be 2.20 weight%, the carrier core material was immersed in the coating resin solution for 30 minutes at 120 degreeC, and was heated and stirred at 200 degreeC for 30 minutes. Thereby, the carrier core material in which the resin was coated at a ratio of 2.20% by weight with respect to the weight of the carrier core material was obtained. The calculation of the coat amount is obtained by the following formula.

  Coating amount (% by weight) = resin weight (g) × solid content concentration (% by weight) / core weight (g)

  The carrier core material coated (coated) with this resin is placed in a hot-air circulating heating device, heated at 200 ° C. for 30 minutes to cure the coating resin, and the carrier for an electrophotographic developer according to Example 1 Got. The same method was performed for Example 2 and the like to obtain a carrier for an electrophotographic developer.

  FIG. 10 is an electron micrograph showing the appearance of the surface of the carrier according to Comparative Example 3. FIG. 11 is an electron micrograph showing the appearance of the surface of the carrier according to Example 3. FIG. 12 is a schematic view showing, in a line, an approximate boundary portion of the coating resin application region in the appearance of the surface of the carrier core material according to Comparative Example 3 shown in FIG. 10. FIG. 13 is a schematic view showing a rough boundary portion of the coating resin application region with lines in the appearance of the surface of the carrier core material according to the third embodiment shown in FIG. FIG. 10 and FIG. 11 show a case where the image is enlarged 2000 times. 12 and 13 are illustrated based on the electron micrographs shown in FIGS. 10 and 11, respectively, from the viewpoint of easy understanding. FIG. 12 and FIG. 13 show regions where the coating resin is coated with dots.

  With reference to FIGS. 10 to 13, it can be understood that the surface of the carrier according to Example 3 is widely covered with the coating resin in the same coating amount. On the other hand, for the carrier according to Comparative Example 3, it can be understood that the area of the surface not covered with the coating resin is considerably wide. That is, for the carrier according to Example 3, it can be understood that a great reduction in the amount of coating resin can be realized.

  In the above embodiment, in the mixing step, the raw material containing calcium is mixed in a solution state. However, the present invention is not limited to this, and may be mixed in a powder state.

  Although the embodiments of the present invention have been described with reference to the drawings, the present invention is not limited to the illustrated embodiments. Various modifications and variations can be made to the illustrated embodiment within the same range or equivalent range as the present invention.

  The carrier core material for an electrophotographic developer, the manufacturing method thereof, the carrier for an electrophotographic developer, and the electrophotographic developer according to the present invention are effectively used when applied to a copying machine or the like that requires high image quality. Is done.

  11, 14, 17 Carrier core material, 12, 15, 18 boundary, 13, 16, 19 grain, 21, 25 granulated powder, 22 particles, 23, 26 hematite phase, 24, 27 magnetite phase.

Claims (10)

General formula: Z _x Ca _y Fe _3-xy O ₄ (0 ≦ x ≦ 1, 0 <y ≦ 1, where Z is from the group consisting of Mg, Mn, Ti, Cu, Zn, Sr, Ni A method for producing a carrier core material for an electrophotographic developer having a core composition represented by (at least one selected metal) as a main component,
A mixing step of mixing a raw material containing iron and a raw material containing calcium;
After the mixing step, a granulation step for granulating the mixed mixture;
A firing step of firing the powdered material granulated by the granulation step at a predetermined temperature to form a magnetic phase;
Material containing the calcium are mixed by the mixing step, Ri raw der containing a water-soluble calcium salt,
The water-soluble calcium salt includes a carrier core material for an electrophotographic developer , comprising at least one of Ca (CH ₃ COO) ₂ (calcium acetate) and Ca (NO ₃ ) ₂ (calcium nitrate) . Production method. The method for producing a carrier core material for an electrophotographic developer according to claim 1 , wherein the water-soluble calcium salt contains Ca (CH ₃ COO) ₂ (calcium acetate). General formula: Z _x Ca _y Fe _3-xy O ₄ (0 ≦ x ≦ 1, 0 <y ≦ 1, where Z is at least one metal selected from the group consisting of Mg, Mn, Ti, Cu, Zn, Sr, and Ni). A manufacturing method of a carrier core material for an electrophotographic developer as a main component,
A mixing step of mixing a raw material containing iron and a raw material containing calcium;
After the mixing step, a granulation step for granulating the mixed mixture;
A firing step of firing the powdered material granulated by the granulation step at a predetermined temperature to form a magnetic phase;
The raw material containing calcium mixed in the mixing step is a raw material containing a water-soluble calcium salt,
The method for producing a carrier core material for an electrophotographic developer, wherein the water-soluble calcium salt is composed of a reducing substance. The method for producing a carrier core material for an electrophotographic developer according to claim 1 or 3 , wherein a substance excluding calcium in the water-soluble calcium salt is composed of a reducing substance. General formula: Z _x Ca _y Fe _3-xy O ₄ (0 ≦ x ≦ 1, 0 <y ≦ 1, where Z is from the group consisting of Mg, Mn, Ti, Cu, Zn, Sr, Ni A carrier core material for an electrophotographic developer whose main component is a core composition represented by at least one selected metal,
A raw material containing iron and a raw material containing calcium are mixed to granulate the mixture, and the granulated particles are fired at a predetermined temperature to form a magnetic phase.
Material containing the calcium, Ri raw der containing a water-soluble calcium salt,
The carrier core material for an electrophotographic developer, wherein the water-soluble calcium salt includes at least one of Ca (CH ₃ COO) ₂ (calcium acetate) and Ca (NO ₃ ) ₂ (calcium nitrate) . General formula: Z _x Ca _y Fe _3-xy O ₄ (0 ≦ x ≦ 1, 0 <y ≦ 1, where Z is at least one metal selected from the group consisting of Mg, Mn, Ti, Cu, Zn, Sr, and Ni). A carrier core material for an electrophotographic developer as a main component,
The raw material containing iron and the raw material containing calcium are mixed to granulate the mixture and granulated
The product is fired at a predetermined temperature to form a magnetic phase,
The raw material containing calcium is a raw material containing a water-soluble calcium salt,
The carrier core material for an electrophotographic developer, wherein the water-soluble calcium salt is composed of a reducing substance. General formula: Z _x Ca _y Fe _3-xy O ₄ (0 ≦ x ≦ 1, 0 <y ≦ 1, where Z is from the group consisting of Mg, Mn, Ti, Cu, Zn, Sr, Ni A carrier core material for an electrophotographic developer whose main component is a core composition represented by at least one selected metal,
When the particle surface of the carrier core material for an electrophotographic developer is observed with a laser microscope at a magnification of 500 times, the length in the X direction in the cross section curved surface is L, and the length in the Y direction in the cross section curved surface is M. And the carrier core material for an electrophotographic developer having a surface property SRa represented by the formula 1 of 0.800 or less, where f (x, y) is a curved cross-section.
The carrier core material for an electrophotographic developer according to claim 5, wherein the core charge amount of the carrier core material for an electrophotographic developer is 10 μC / g or more. A carrier for an electrophotographic developer used in an electrophotographic developer,
The carrier core material for an electrophotographic developer according to any one of claims 5 to 8 ,
An electrophotographic developer carrier comprising: a resin that covers a surface of the carrier core material for the electrophotographic developer. An electrophotographic developer used for electrophotographic development,
The carrier for an electrophotographic developer according to claim 9 ,
An electrophotographic developer comprising: a toner capable of being charged in electrophotography by frictional charging with the carrier for electrophotographic developer.