Magnetic carrier, two-component developer, and replenishment developer

Abstract

To provide a magnetic carrier that exhibits excellent contamination resistance and abrasion resistance.SOLUTION: A magnetic carrier includes a magnetic core and coating resin coating the surface of the magnetic core, the coating resin contains resin A and resin B, contents of the resin A are 1 mass% or more and 50 mass% or less and contents of the resin B are 50 mass% or more and 99 mass% or less on the basis of the coating resin, the resin A has a specific unit Y1 and a specific unit Y2, the resin B contains 0.1 mass% or less of the specific unit Y2, a formula (a) 0.90≤(a+b) / X≤1.00 and a formula (b) 1.00≤a / b≤30.0 are satisfied when the mass of the resin A is X, the mass of the unit Y1 in the resin A is a, and the mass of the unit Y2 in the resin A is b, and a formula (c) 0≤|SPa-SPb|≤2.0 is satisfied when a SP value of the unit Y1 is SPa and a SP value of the resin B is SPb.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a magnetic carrier, a two-component developer, and a replenishment developer used in an image forming method for visualizing an electrostatic image using electrophotography. [Background technology]

[0002] Conventionally, electrophotographic image formation methods generally involve forming an electrostatic latent image on an electrostatic latent image carrier using various means, and then developing the electrostatic latent image by attaching toner to the electrostatic latent image. For this development, a two-component development method is widely used in which carrier particles called magnetic carriers are mixed with the toner, and the toner is frictionally charged to impart an appropriate amount of positive or negative charge to the toner, with the charge acting as a driving force for development.

[0003] In the two-component development method, the magnetic carrier can be given functions such as stirring, transporting, and charging the developer, so the division of functions between the carrier and the toner is clear, which has the advantage of good controllability of developer performance.Here, the magnetic carrier often has a core that is magnetic to achieve transportability, and the core is coated with a coating resin that provides the ability to impart charge to the toner.

[0004] In recent years, technological advances in the electrophotography field have led to ever-increasing demands for longer device life, requiring carriers to maintain their chargeability even over long periods of use. However, it is generally known that the carrier's chargeability declines as a result of the adhesion of toner components to the carrier, resulting in a decrease in charge sites and image defects such as changes in color.

[0005] As a means for achieving the durability against adhesion of the above-mentioned toner components (hereinafter referred to as "contamination resistance"), an example has been adopted in which a material with low surface free energy, such as a silicone resin, is used as a coating resin (Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-91093 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-138230 [Patent Document 3] Japanese Patent Application Laid-Open No. 2013-3428 Summary of the Invention [Problem to be solved by the invention]

[0007] However, although materials with low surface free energy such as silicone resins can generally suppress adhesion of toner components, etc., they have weak molecular interactions and are easily destroyed by external forces, etc. For this reason, when silicone resins are used as the coating resin for carriers, the coating resin can be worn away by mechanical loads that occur during stirring or transport within the developing machine (hereinafter referred to as "wear resistance"). This wear of the coating resin reduces the surface resistance of the carrier, which can result in a decrease in the carrier's charge-imparting ability (Patent Documents 1 to 3).

[0008] One possible example of achieving the above-mentioned abrasion resistance is to use a silicone-modified resin with trifunctional silicon attached to the terminal, but this structure does not sufficiently reduce the surface free energy of the carrier surface, and it has been found that contamination resistance does not improve (Patent Document 2).On the other hand, when a resin having a silicone structure in the side chain is used as a structure to further reduce the surface free energy, the surface free energy between molecules becomes small, and it has been confirmed that abrasion resistance becomes insufficient, just as when the above-mentioned silicone resin is used (Patent Document 3).

[0009] That is, to realize a highly stable carrier, it is necessary to simultaneously obtain both contamination resistance to prevent adhesion of toner components and wear resistance to prevent wear of the coating due to mechanical loads.

[0010] In view of the above, an object of the present invention is to provide a stable carrier that is resistant to contamination and abrasion and that achieves reduced fogging, reduced toner scattering, stable image density, and developability even when used for a long period of time in an image forming method using a two-component development system. [Means for solving the problem]

[0011] As a result of extensive research, the present inventors have found that the use of resin A and resin B having the following structures makes it possible to provide a carrier with good contamination resistance and wear resistance. Resin A has a structure in which a silicone structure similar to that of the silicone resin is grafted onto the main chain, and this silicone structure reduces the surface free energy, improving contamination resistance. Resin B also has a structure that is highly compatible with the main chain of Resin A, allowing Resin A and Resin B to mix together, thereby improving abrasion resistance. As mentioned above, when only a resin with a grafted silicone structure, such as Resin A, is used, the abrasion resistance of the carrier is insufficient. However, by using Resin B, which has high compatibility with the main chain of Resin A, in combination, the main chain of Resin A and Resin B strongly interact with each other, making it possible to achieve abrasion resistance.

[0012] That is, one embodiment of the present invention includes a magnetic core and a coating resin that coats the surface of the magnetic core, The coating resin contains resin A and resin B, Based on the total mass of the coating resin, the content of resin A is 1% by mass or more and 50% by mass or less, and the content of resin B is 50% by mass or more and 99% by mass or less, The resin A has a unit Y1 represented by the following formula (1) and a unit Y2 represented by the following formula (2), The resin B has a content of units Y2 represented by the following formula (2) of 0.1% by mass or less, When the mass of the resin A, the mass of the unit Y1 in the resin A, and the mass of the unit Y2 in the resin A are X, a, and b, respectively, X, a, and b are expressed by the following formulas (a) and (b): 0.90≦(a+b) / X≦1.00 (a) 1.00≦a / b≦30.0 (b) Fulfilling When the SP value of the unit Y1 and the SP value of the resin B are SPa and SPb, respectively, the SPa and SPb are expressed by the following formula (c): 0≦|SPa-SPb|≦2.0 (c) characterized by satisfying (In formula (1), R1 represents H or CH3; R2 represents a hydrocarbon group having 1 to 8 carbon atoms which may have a substituent, and the substituent is a hydroxy group or a carboxy group. (In formula (2), R3 represents H or CH3; R4 represents H or CH3; R5 represents a single bond or a hydrocarbon group having 1 to 10 carbon atoms; R6 represents a hydrocarbon group having 1 to 10 carbon atoms; R7 represents H, CH3 or Si(CH3)3; n represents an integer between 2 and 150.) The object is to provide a magnetic carrier. [ka] [ka]

[0013] Another embodiment of the present invention is to provide a two-component developer comprising the magnetic carrier and a toner. Another embodiment of the present invention is to provide a replenishment developer comprising the magnetic carrier and toner. [Effects of the Invention]

[0014] According to the present invention, a stable carrier having contamination resistance and abrasion resistance is provided, which realizes reduced fogging, reduced toner scattering, stable image density, and developability even after long-term use. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic diagram of an example of a surface treatment device. [Figure 2] FIG. 1 is a schematic diagram illustrating an example of an image forming apparatus. [Figure 3] 1 is a schematic diagram illustrating an example of an image forming method applied to a full-color image forming apparatus. [Figure 4] FIG. 2 is a schematic diagram of a device for measuring the resistivity of a magnetic carrier and a porous magnetic core. DETAILED DESCRIPTION OF THE INVENTION

[0016] In the present invention, unless otherwise specified, the expressions "xx or more and xx or less" and "xx to xx" representing a numerical range mean a numerical range including the lower and upper limits, which are the endpoints.

[0017] The magnetic carrier of the present invention is a magnetic carrier having a magnetic core and a coating resin that coats the surface of the magnetic core, The coating resin contains resin A and resin B, Based on the total mass of the coating resin, the content of resin A is 1% by mass or more and 50% by mass or less, and the content of resin B is 50% by mass or more and 99% by mass or less, The resin A has a unit Y1 represented by the following formula (1) and a unit Y2 represented by the following formula (2), The resin B has a content of units Y2 represented by the following formula (2) of 0.1% by mass or less, When the mass of the resin A, the mass of the unit Y1 in the resin A, and the mass of the unit Y2 in the resin A are X, a, and b, respectively, X, a, and b are expressed by the following formulas (a) and (b): 0.90≦(a+b) / X≦1.00 (a) 1.00≦a / b≦30.0 (b) Fulfilling When the SP value of the unit Y1 and the SP value of the resin B are SPa and SPb, respectively, the SPa and SPb are expressed by the following formula (c): 0≦|SPa-SPb|≦2.0 (c) The present invention is characterized in that: (In formula (1), R1 represents H or CH3; R2 represents a hydrocarbon group having 1 to 8 carbon atoms which may have a substituent, and the substituent is a hydroxy group or a carboxy group. (In formula (2), R3 represents H or CH3; R4 represents H or CH3; R5 represents a single bond or a hydrocarbon group having 1 to 10 carbon atoms; R6 represents a hydrocarbon group having 1 to 10 carbon atoms; R7 represents H, CH3 or Si(CH3)3; n represents an integer between 2 and 150.) [ka] [ka]

[0018] As mentioned above, when only a resin with low surface free energy such as a silicone resin is used as the coating resin, the abrasion resistance is deteriorated. The carrier of the present invention contains resin A and resin B, and resin A has a structure similar to that of the silicone resin, and this structure is grafted to the main chain, causing a decrease in surface free energy due to the silicone structure, thereby improving contamination resistance. Furthermore, as will be described later, resin B has a structure that is highly compatible with the main chain of resin A, so that resin A and resin B are less likely to peel due to mechanical loads such as shear generated by a developing machine, thereby improving abrasion resistance.

[0019] The resin A has a unit Y1 represented by the above formula (1) and a unit Y2 represented by the following formula (2). The unit Y2 has a silicone structure, which reduces the surface free energy and improves the stain resistance.

[0020] In the unit Y1, in formula (1), R1 represents H or CH3, and R2 represents a hydrocarbon group of 1 to 8 carbon atoms which may have a substituent, preferably an alkyl group of 1 to 6 carbon atoms which may have a substituent. The substituent in R2 is a hydroxy group or a carboxy group. Specific methods for introducing R1 and R2 include copolymerizing the following monomers when polymerizing resin A: methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate, cyclobutyl acrylate, cyclohexyl acrylate, cyclopentyl acrylate, cyclooctyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, hexyl methacrylate, cyclobutyl methacrylate, cyclohexyl methacrylate, cyclopentyl methacrylate, cyclooctyl methacrylate, 2-hydroxyethyl acrylate, 2-carboxyethyl acrylate, 2-hydroxyethyl methacrylate, and 2-carboxyethyl methacrylate.

[0021] In the unit Y2, R3 represents H or CH3, R4 represents H or CH3, and R5 represents a single bond or a hydrocarbon group having 1 to 10 carbon atoms, preferably an alkylene group having 1 to 6 carbon atoms. R6 represents a hydrocarbon group having 1 to 10 carbon atoms, preferably an alkyl group or a phenyl group having 1 to 6 carbon atoms. R7 represents H, CH3, or Si(CH3)3, and n represents an integer of 2 or more and 150 or less. Specific methods for introducing these substituents include, for example, copolymerizing an acrylate ester, methacrylate ester, or 2-butenoate ester in which a silicone structure has been esterified when polymerizing resin A.

[0022] In the resin A, when the mass of the resin A, the mass of the unit Y1 in the resin A, and the mass of the unit Y2 in the resin A are X, a, and b, respectively, X, a, and b are expressed by the following formulas (a) and (b): 0.90≦(a+b) / X≦1.00 (a) 1.00≦a / b≦30.0 (b) This relationship indicates that the resin A contains the units Y1 and Y2 at 90% by mass or more of the total units, and that the mass of the units Y2 is the same mass % as the unit Y1 multiplied by 30. If (a + b) / X is less than 0.90, the compatibility with the resin B decreases, resulting in poor abrasion resistance, or the surface free energy decreases, resulting in poor stain resistance, which is undesirable. Furthermore, if a / b is less than 1.00, the ratio of units Y2 to units Y1 becomes too high, resulting in a structure with a too low surface free energy and therefore poor abrasion resistance. Conversely, if a / b is greater than 30, the surface free energy becomes too high, resulting in poor stain resistance.

[0023] The proportion of resin A contained in the coating resin is 1 to 50% by mass. If the proportion of resin A contained in the coating resin is less than 1% by mass, the surface free energy does not decrease, resulting in insufficient contamination resistance. If the proportion of resin A contained in the coating resin is more than 50% by mass, the decrease in intermolecular forces due to the low surface free energy exceeds the abrasion resistance obtained through interaction with resin B, resulting in insufficient abrasion resistance. The proportion of resin A contained in the coating resin is preferably in the range of 1% to 20% by mass, more preferably 3 to 20% by mass.

[0024] The proportion of resin B contained in the coating resin is 50 to 99% by mass. If the proportion of resin B contained in the coating resin is less than 50% by mass, the resin strength will be insufficient, resulting in poor abrasion resistance. If the proportion of resin B contained in the coating resin is more than 99% by mass, the effect of the component with low surface free energy will be insufficient, resulting in poor stain resistance. The proportion is preferably 80% by mass or more and 99% by mass or less.

[0025] When the SP value of the unit Y1 and the SP value of the resin B are respectively SPa and SPb, the SP and SPb are expressed by the following formula (c): 0≦|SPa-SPb|≦2.0 (c) Meet the following. The SP value is calculated by the following method. Formula: SP value = √(Ev / v) = √(ΣΔei / ΣΔvi) In the formula, Ev: evaporation energy (J / mol), v: molar volume (cm 3 / mol), Δei: evaporation energy of each atom or atomic group, Δvi: molar volume of each atom or atomic group It is as follows.

[0026] By satisfying the above relational expression (c), the compatibility with the resin A and the resin B is enhanced, and the wear resistance is improved. When |SPa - SPb| is greater than 2.0, the compatibility between the resin A and the resin B is low, and the intermolecular interaction decreases, so the wear resistance deteriorates. The smaller |SPa - SPb| is, the higher the compatibility, and it is preferable that it is 1.0 or less because the wear resistance is further improved.

[0027] When the sum of the number of units Y1 and units Y2 of the resin A is m, it is preferable that the resin A satisfies the following formula (d). 50 ≤ m ≤ 250 (d) When m is 50 or more, the molecular weight becomes sufficiently high, so the wear resistance is further improved. When m is 250 or less, the interaction between the resin A and the resin B is further enhanced, so the wear resistance and stain resistance are further improved.

[0028] In the magnetic carrier of the present invention, it is preferable that Si by ESCA analysis on the magnetic carrier surface is 1.0 atomic % or more and 15.0 atomic % or less. Since Si being 1.0 atomic % or more can lower the surface free energy of the carrier, the stain resistance is further improved. Since Si being 15.0 atomic % or less increases the intermolecular interaction near the carrier surface, the wear resistance is further improved.

[0029] The Si atomic concentration is measured as follows. <Measurement method of Si atomic concentration by XPS> The magnetic carrier is attached to the indium foil, and the particles are attached evenly so that the indium foil is not exposed. The measurement conditions are as follows. Equipment: PHI5000VERSAPROBE II (ULVAC-PHI, Inc.) Irradiation: Al Kα ray Output: 25W 15kV Pass Energy: 58.7 eV Step size: 0.125eV XPS peaks: C1s, O1s, Si2p, Ti2p, Sr3d

[0030] In the resin A, n in formula (2) represents the length of the side chain formed by the silicone structure of the silicone graft structure. When n is 2 to 150, it is possible to reduce the surface free energy of the carrier coat resin. When n is 1 or less, the surface free energy cannot be reduced, resulting in poor stain resistance. When n is greater than 150, the interaction between the resin A and the resin B is reduced, resulting in poor abrasion resistance. When n is 5 or more and 60 or less, it is preferable because the abrasion resistance and stain resistance are improved.

[0031] The resin A may have a functional group such as a nitrogen-containing group, a carboxyl group, or a hydroxyl group. By having these, it is possible to suppress the charge-up of the developer, particularly in a low-humidity environment. In addition, since the resin A has a hydroxyl value, the effect of hydrogen bonding is also exerted, which is preferable because it further improves the abrasion resistance.

[0032] When a carboxyl group is used, the acid value of the resin A is preferably in the range of 5 to 100 mgKOH / mg. When the acid value of the resin A is 5 or more, the charge build-up is improved, and when the acid value of the resin A is 100 or less, the charge retention of the developer is improved.

[0033] When hydroxyl groups are used, the preferred range of the hydroxyl value of resin A is 5 to 50 mgKOH / mg. When the hydroxyl value of resin A is 5 or more, the charge build-up is improved, and when the hydroxyl value of resin A is 50 or less, the charge retention of the developer is improved.

[0034] In the resin B, when the SP value of the unit Y1 and the SP value of the resin B are SPa and SPb, respectively, the SPa and SPb are expressed by the following formula (c): 0≦|SPa-SPb|≦2.0 (c) The structure is not particularly limited, and examples of resins that can be used include acrylic resins, urethane resins, polyethylene, polyethylene terephthalate, polystyrene, and phenolic resins.

[0035] From the viewpoint that the SP value of resin B is closer to the SP value of resin A and compatibility with resin A is enhanced, resin B is preferably an acrylic resin.

[0036] The structure of the resin B is preferable because it has the unit Y1, which reduces the difference in SP value with the resin A and improves compatibility, and it is more preferable that the resin B contains 75 mass % or more of the unit Y1.

[0037] The resin B preferably contains the unit Y3 represented by the following formula (3), and the content thereof is preferably 1% by mass or more and 75% by mass or less. [ka] In formula (3), R8 represents a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclopentyl group, a cyclobutyl group, or a cyclopropyl group.

[0038] Resin B preferably contains an alicyclic hydrocarbon group such as that contained in unit Y3, which makes the surface (coating surface) of the resin coating layer that coats the surface of the magnetic core smooth, suppresses adhesion of toner-derived components such as toner and external additives that impart fluidity to the toner, and further improves contamination resistance. Unit Y3 may contain only one type of structure, or two or more types.

[0039] When synthesizing Resin B, the (meth)acrylic acid ester monomer having an alicyclic hydrocarbon group is preferably used in an amount of 50 parts by mass or more and 90 parts by mass or less, based on 100 parts by mass of all monomers used in the synthesis of Resin B.

[0040] From the viewpoint of coating stability, the weight average molecular weight (Mw) of Resin B is preferably 20,000 or more and 120,000 or less, and more preferably 30,000 or more and 100,000 or less.

[0041] The acid value of resin B is preferably 0 mgKOH / g or more and 3.0 mgKOH / g or less, more preferably 0 mgKOH / g or more and 2.8 mgKOH / g or less, and particularly preferably 0 mgKOH / g or more and 2.5 mgKOH / g or less. When resin B has an acid value of 3.0 mgKOH / g or less, self-aggregation of the resin due to the acid value is less likely to occur, and the smoothness of the surface of the resin coating layer (coating surface) is less likely to decrease. The acid value of resin B can be controlled by using a monomer having a polar group such as a carboxy group or a sulfo group (sulfonic acid group) during the synthesis of coating resin A and adjusting the amount of monomer added. However, since a low acid value of resin A is preferred, it is preferable not to use a monomer having a polar group. Even when a resin is synthesized using only monomers that form ester bonds, a slight acid value may occur in the synthesized resin. This is thought to be due to the decomposition of some ester bonds during resin synthesis (polymerization), generating carboxyl groups.

[0042] Resin B is preferably a polymer (copolymer) obtained by copolymerizing a (meth)acrylic acid ester monomer having an alicyclic hydrocarbon group with a macromonomer. When a macromonomer is used in the synthesis of Resin B, the adhesion between the resin coating layer and the magnetic core improves, and the magnetic carrier's ability to impart charge to the toner improves.

[0043] The macromonomer is preferably a macromonomer obtained by polymerizing at least one selected from the group consisting of methyl acrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, styrene, acrylonitrile, and methacrylonitrile.

[0044] The weight average molecular weight (Mw) of the macromonomer is preferably 2,000 or more and 10,000 or less, and more preferably 3,000 or more and 8,000 or less.

[0045] When synthesizing Resin B, the macromonomer is preferably used in an amount of 5.0 parts by mass to 40.0 parts by mass, where the total amount of monomers used in synthesizing Coating Resin A is 100 parts by mass.

[0046] When synthesizing Resin B, the addition of a methacrylate ester monomer in particular strengthens molecular entanglement, improving the adhesion of the coating resin to the magnetic core. As a result, the coating will not peel off even when subjected to loads such as from the stirring member of the developing device, maintaining stable charge imparting ability over the long term and enabling the output of high-quality images.

[0047] The resin coating of the present invention preferably contains conductive fine particles. The conductive fine particles can appropriately control the resistivity of the electrophotographic carrier. As a result, countercharge can be released after the toner is developed, and white spots can be suppressed. The content of the conductive fine particles added to the coating resin is preferably 0.1 to 20 parts by mass per 100 parts by mass of the coating resin. If the content of the conductive fine particles is less than 0.1 part by mass, it is difficult to obtain the effect of adding the conductive fine particles, and if the content of the conductive fine particles exceeds 20 parts by mass, there is a concern that the color may be reduced due to the detachment of the conductive fine particles. Examples of conductive fine particles include carbon black, titanium oxide, and silver.

[0048] Furthermore, fine particles may be contained in the coating resin for the purpose of enhancing the ability to impart charge to the toner and improving releasability. The fine particles contained in the resin coating may be fine particles of either organic or inorganic materials, but crosslinked resin fine particles or inorganic fine particles that have the strength to maintain the shape of the fine particles when coated are preferred. Examples of crosslinked resins that form crosslinked resin fine particles include crosslinked polymethyl methacrylate resins, crosslinked polystyrene resins, melamine resins, guanamine resins, urea resins, phenolic resins, and nylon resins. Examples of inorganic fine particles include silica, alumina, titania, etc.

[0049] The content of the fine particles in the coating resin is 0.1 mass parts per 100 mass parts of the coating resin. It is preferable that the content is 20 parts by mass or more and 20 parts by mass or less.

[0050] The magnetic core particles of the present invention can be any known magnetic particles such as magnetite particles, ferrite particles, magnetic material-dispersed resin particles, etc. Among these, magnetic particles obtained by filling the pores of porous magnetic particles with a resin or magnetic material-dispersed resin particles, i.e., magnetic particles containing a magnetic oxide and a resin composition, are preferred from the viewpoint of extending the life of the magnetic carrier because they can reduce the specific gravity of the magnetic carrier.

[0051] Reducing the specific gravity of the magnetic carrier reduces the load on the toner in the developer state in the developing device, prevents the adhesion of toner components to the magnetic carrier surface, reduces the load on the carrier itself, and further suppresses peeling, chipping, and abrasion of the resin coating layer. It also improves dot reproducibility, making it possible to obtain high-resolution images.

[0052] In addition, the resin to be contained in the pores of the porous magnetic particles can be a copolymer resin used as a coating resin, but is not limited to this and can be any known resin such as a thermoplastic resin or a thermosetting resin.

[0053] As the thermoplastic resin, copolymers used as coating resins are preferred, but other examples include the following: polystyrene, polymethyl methacrylate, styrene-acrylic acid ester copolymers, styrene-methacrylic acid ester copolymers, styrene-butadiene copolymers, ethylene-vinyl acetate copolymers, polyvinyl chloride, polyvinyl acetate, polyvinylidene fluoride resins, fluorocarbon resins, perfluorocarbon resins, solvent-soluble perfluorocarbon resins, polyvinylpyrrolidone, petroleum resins, novolac resins, saturated alkyl polyester resins, aromatic polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyarylate, polyamide resins, polyacetal resins, polycarbonate resins, polyethersulfone resins, polysulfone resins, polyphenylene sulfide resins, and polyether ketone resins.

[0054] Examples of thermosetting resins include phenolic resins, modified phenolic resins, maleic resins, alkyd resins, epoxy resins, acrylic resins, unsaturated polyesters obtained by polycondensation of maleic anhydride, terephthalic acid, and polyhydric alcohols, urea resins, melamine resins, urea-melamine resins, xylene resins, toluene resins, guanamine resins, melamine-guanamine resins, acetoguanamine resins, glyptal resins, furan resins, silicone resins, polyimides, polyamide-imide resins, polyetherimide resins, and polyurethane resins.

[0055] One method for filling the voids of porous ferrite particles with a resin component is to dilute the resin component in a solvent and then add the porous magnetic core particles to the diluted solution. The solvent used here can be any solvent capable of dissolving each resin component. For organic solvent-soluble resins, organic solvents such as toluene, xylene, cellosolve butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, and methanol can be used. For water-soluble or emulsion-type resins, water can be used. Methods for adding the solvent-diluted resin component to the interior of the porous magnetic core particles include impregnating the resin component using a coating method such as immersion, spraying, brushing, fluidized bed coating, or kneading, followed by volatilizing the solvent. When filling with a thermosetting resin, the solvent is volatilized, and then the temperature is raised to the curing temperature of the resin used to initiate a curing reaction.

[0056] On the other hand, specific methods for producing magnetic material-dispersed resin particles include the following. For example, submicron magnetic materials such as iron powder, magnetite particles, and ferrite particles are kneaded in a thermoplastic resin so as to disperse them, and then pulverized to the desired carrier particle size, followed by thermal or mechanical spheronization as necessary. Alternatively, magnetic material-dispersed resin particles can be produced by dispersing the magnetic material in a monomer and polymerizing the monomer to form a resin.

[0057] In this case, examples of the resin include vinyl resin, polyester resin, epoxy resin, phenol resin, urea resin, polyurethane resin, polyimide resin, cellulose resin, silicone resin, acrylic resin, and polyether resin. The resin may be a single type or a mixture of two or more types. Phenolic resin is particularly preferred because it increases the strength of the magnetic core. The true density and resistivity can be adjusted by adjusting the amount of magnetic material. Specifically, in the case of magnetic particles, it is preferable to add 70% by mass or more and 95% by mass or less of the carrier.

[0058] The magnetic core preferably has a volume-based 50% diameter (D50) of 20 μm or more and 80 μm or less in order to be able to uniformly coat the coating resin, prevent carrier adhesion, and ensure an appropriate density of the developer magnetic brush to obtain high-quality images.

[0059] The resistivity of the magnetic core is 1.0 x 10 at an electric field strength of 1000 (V / cm). 5 (Ω cm) or more 1.0×10 14 (Ω·cm) or less is preferable because good developability can be obtained. The method for coating the magnetic core surface with the coating resin is not particularly limited and can be performed by any known method. For example, there is the so-called immersion method, in which the magnetic core and coating resin solution are stirred while the solvent is volatilized, and the coating resin is coated on the magnetic core surface. Specific examples include a universal mixer (manufactured by Fuji Paudal Co., Ltd.) and a Nauta Mixer (manufactured by Hosokawa Micron Corporation). Another method involves spraying the coating resin solution from a spray nozzle while forming a fluidized bed to coat the magnetic core surface with the coating resin. Specific examples include a Spiracoater (manufactured by Okada Seiko Co., Ltd.) and a Spiraflow (manufactured by Freund Corporation). Another method involves dry coating the magnetic core with the coating resin in particle form. Specific examples include treatment methods using devices such as a Hybridizer (manufactured by Nara Machinery Works Co., Ltd.), a Mechanofusion (manufactured by Hosokawa Micron Corporation), a Hyflex Gral (manufactured by Fukae Powtec), and a Theta Composer (manufactured by Tokuju Kogyosho Co., Ltd.).

[0060] Next, the magnetic carrier will be described. The magnetic carrier has a magnetization strength of 40 (Am) under a magnetic field of 5000 / 4π (kA / m). 2 / kg) or more 70(Am 2 / kg) or less. When the magnetization strength of the magnetic carrier is within the above range, the magnetic binding force to the developing sleeve is appropriate, so that carrier adhesion can be more effectively suppressed. In addition, the stress applied to the toner in the magnetic brush can be reduced, so that toner deterioration and adhesion to other components can be effectively suppressed. The strength of magnetization of the magnetic carrier can be adjusted appropriately by the amount of resin contained therein.

[0061] The residual magnetization of the magnetic carrier is 20.0 (Am 2 / kg) or less, and 10.0 (Am 2 When the residual magnetization of the magnetic carrier is within the above range, particularly good fluidity can be obtained as a developer, and good dot reproducibility can be obtained.

[0062] The magnetic carrier has a true density of 2.5 (g / cm 3 ) or more 5.5 (g / cm 3 ) or less, and 3.0 (g / cm 3 ) or more 5.0 (g / cm 3 ) or less is more preferable. A two-component developer containing a magnetic carrier having a true density in this range exerts a small load on the toner, and adhesion of the toner components to the magnetic carrier is suppressed. Furthermore, a true density in this range is preferable for the magnetic carrier in order to achieve both good developability at low electric field strength and prevention of carrier adhesion.

[0063] The magnetic carrier preferably has a volume-based 50% diameter (D50) of 21 μm or more and 81 μm or less from the viewpoints of the ability to charge the toner, suppressing carrier adhesion to the image area, and achieving high image quality, and more preferably has a volume-based 50% diameter (D50) of 25 μm or more and 60 μm or less.

[0064] Next, the toner constitution that is preferable for achieving the object of the present invention will be described in detail below. <Binder resin> The toner particles of the present invention may use the following polymers as the binder resin: homopolymers of styrene and its substituted derivatives, such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene; styrene-based copolymers, such as styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylic acid ester copolymer, and styrene-methacrylic acid ester copolymer; styrene-based copolymer resins, polyester resins, mixtures of polyester resins and vinyl resins, or hybrid resins in which both are partially reacted; polyvinyl chloride, phenolic resins, naturally modified phenolic resins, naturally resin-modified maleic acid resins, acrylic resins, methacrylic resins, polyvinyl acetate, silicone resins, polyester resins, polyurethanes, polyamide resins, furan resins, epoxy resins, xylene resins, polyethylene resins, and polypropylene resins. Among these, those containing polyester resins as the main component are preferred from the viewpoint of low-temperature fixability.

[0065] Monomers used in the polyester unit of the polyester resin include polyhydric alcohols (divalent or trivalent or higher alcohols), polycarboxylic acids (divalent or trivalent or higher carboxylic acids), their acid anhydrides, or their lower alkyl esters. To create a branched polymer that exhibits "strain hardening," partial crosslinking within the molecule of the amorphous resin is effective, and for this purpose, it is preferable to use a polyfunctional compound with a valence of three or more. Therefore, it is preferable to include a trivalent or higher carboxylic acid, its acid anhydride, or its lower alkyl ester, and / or a trivalent or higher alcohol as the raw material monomer for the polyester unit.

[0066] As the polyhydric alcohol monomer used in the polyester unit of the polyester resin, the following polyhydric alcohol monomers can be used.

[0067] Dihydric alcohol components include ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 2-ethyl-1,3-hexanediol, hydrogenated bisphenol A, and bisphenols represented by formula (A) and their derivatives; [ka] (In the formula, R is an ethylene or propylene group, x and y are each an integer of 0 or more, and the average value of x+y is 0 or more and 10 or less.) Diols represented by formula (B); [ka] (In formula (B), R' is -CH2CH2-, -CH2-CH(CH3)-, or -CH2-C(CH3)2-, x' and y' are each an integer of 0 or greater, and the average value of x'+y' is 0 or greater and 10 or less.) Examples include:

[0068] Examples of trihydric or higher alcohol components include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, and 1,3,5-trihydroxymethylbenzene. Among these, glycerol, trimethylolpropane, and pentaerythritol are preferred. These dihydric and trihydric or higher alcohols can be used alone or in combination.

[0069] As the polycarboxylic acid monomer used in the polyester unit of the polyester resin, the following polycarboxylic acid monomers can be used.

[0070] Examples of dicarboxylic acid components include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, malonic acid, n-dodecenylsuccinic acid, isododecenylsuccinic acid, n-dodecylsuccinic acid, isododecylsuccinic acid, n-octenylsuccinic acid, n-octylsuccinic acid, isooctenylsuccinic acid, isooctylsuccinic acid, anhydrides of these acids, and lower alkyl esters thereof. Of these, maleic acid, fumaric acid, terephthalic acid, and n-dodecenylsuccinic acid are preferably used.

[0071] Examples of trivalent or higher carboxylic acids, their acid anhydrides, or their lower alkyl esters include 1,2,4-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra(methylenecarboxyl)methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, empol trimer acid, and their acid anhydrides or lower alkyl esters. Among these, 1,2,4-benzenetricarboxylic acid, i.e., trimellitic acid or its derivatives, is particularly preferred due to its low cost and easy reaction control. These divalent carboxylic acids and trivalent or higher carboxylic acids can be used alone or in combination.

[0072] The method for producing the polyester unit of the present invention is not particularly limited, and known methods can be used. For example, the aforementioned alcohol monomer and carboxylic acid monomer are simultaneously charged and polymerized via an esterification reaction or transesterification reaction and a condensation reaction to produce a polyester resin. The polymerization temperature is not particularly limited, but is preferably in the range of 180°C to 290°C. Polymerization of the polyester unit can be performed using a polymerization catalyst such as a titanium-based catalyst, a tin-based catalyst, zinc acetate, antimony trioxide, or germanium dioxide. In particular, the binder resin of the present invention preferably contains a polyester unit polymerized using a tin-based catalyst.

[0073] In addition, it is preferable from the viewpoint of fogging that the acid value of the polyester resin is 5 mgKOH / g or more and 20 mgKOH / g or less, and the hydroxyl value is 20 mgKOH / g or more and 70 mgKOH / g or less, since this reduces the amount of moisture adsorption in a high-temperature, high-humidity environment and keeps the non-electrostatic adhesion force low.

[0074] The binder resin may be a mixture of a low molecular weight resin and a high molecular weight resin. The ratio of the high molecular weight resin to the low molecular weight resin is preferably 40 / 60 or more and 85 / 15 or less by mass from the viewpoint of low temperature fixability and hot offset resistance.

[0075] <Release agent> Examples of waxes that can be used in the toner of the present invention include: hydrocarbon waxes such as low-molecular-weight polyethylene, low-molecular-weight polypropylene, alkylene copolymers, microcrystalline wax, paraffin wax, and Fischer-Tropsch wax; oxides of hydrocarbon waxes such as oxidized polyethylene wax or block copolymers thereof; waxes containing fatty acid esters as the main component such as carnauba wax; and partially or completely deoxidized fatty acid esters such as deoxidized carnauba wax. Further examples include the following. Saturated straight-chain fatty acids such as palmitic acid, stearic acid, and montanic acid; unsaturated fatty acids such as brassidic acid, eleostearic acid, and valinaric acid; saturated alcohols such as stearyl alcohol, aralkyl alcohols, behenyl alcohol, carnaubyl alcohol, ceryl alcohol, and melissyl alcohol; polyhydric alcohols such as sorbitol; esters of fatty acids such as palmitic acid, stearic acid, behenic acid, and montanic acid with alcohols such as stearyl alcohol, aralkyl alcohols, behenyl alcohol, carnaubyl alcohol, ceryl alcohol, and melissyl alcohol; fatty acid amides such as linoleic acid amide, oleic acid amide, and lauric acid amide; methylene bisstearic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, hexamethylene Saturated fatty acid bisamides such as bisstearamide; unsaturated fatty acid amides such as ethylene bisoleamide, hexamethylene bisoleamide, N,N'-dioleyl adipamide, and N,N'-dioleyl sebacamide; aromatic bisamides such as m-xylene bisstearamide and N,N'-distearyl isophthalamide; fatty metal salts (commonly known as metal soaps) such as calcium stearate, calcium laurate, zinc stearate, and magnesium stearate; waxes obtained by grafting aliphatic hydrocarbon waxes with vinyl monomers such as styrene and acrylic acid; partial esters of fatty acids and polyhydric alcohols such as behenic acid monoglyceride; and methyl ester compounds having hydroxyl groups obtained by hydrogenating vegetable oils and fats.

[0076] Among these waxes, hydrocarbon waxes such as paraffin wax and Fischer-Tropsch wax, or fatty acid ester waxes such as carnauba wax are preferred from the viewpoint of improving low-temperature fixability and fixation separation property, and in the present invention, hydrocarbon waxes are more preferred from the viewpoint of further improving hot offset resistance.

[0077] In the present invention, the wax is preferably used in an amount of 3 parts by mass or more and 8 parts by mass or less per 100 parts by mass of the binder resin.

[0078] Furthermore, in an endothermic curve during temperature rise measured with a differential scanning calorimetry (DSC) device, the peak temperature of the maximum endothermic peak of the wax is preferably 45° C. or higher and 140° C. or lower. If the peak temperature of the maximum endothermic peak of the wax is within the above range, it is preferable because it is possible to achieve both storage stability and hot offset resistance of the toner.

[0079] <Coloring agent> The toner particles of the present invention may contain a colorant. Examples of the colorant include the following.

[0080] Examples of black colorants include carbon black, and those toned to black using a yellow colorant, a magenta colorant, and a cyan colorant. As the colorant, a pigment may be used alone, but it is more preferable to use a dye and a pigment in combination to improve the clarity from the viewpoint of the image quality of a full-color image.

[0081] Examples of pigments for magenta toner include CI Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 41, 48:2, 48:3, 48:4, 49, 50, 51, 52, 53, 54, 55, 57:1, 58, 60, 63, 64, 68, 81:1, 83, 87, 88, 89, 90, 112, 114, 122, 123, 146, 147, 150, 163, 184, 202, 206, 207, 209, 238, 269, 282; CI Pigment Violet 19; CI Bat Red 1, 2, 10, 13, 15, 23, 29, 35. Dyes for magenta toner include solvent dyes such as CI Solvent Red 1, 3, 8, 23, 24, 25, 27, 30, 49, 81, 82, 83, 84, 100, 109, and 121; CI Disperse Red 9; CI Solvent Violet 8, 13, 14, 21, and 27; and CI Disperse Violet 1; and basic dyes such as CI Basic Red 1, 2, 9, 12, 13, 14, 15, 17, 18, 22, 23, 24, 27, 29, 32, 34, 35, 36, 37, 38, 39, and 40; and CI Basic Violet 1, 3, 7, 10, 14, 15, 21, 25, 26, 27, and 28.

[0082] Examples of pigments for cyan toner include CI Pigment Blue 2, 3, 15:2, 15:3, 15:4, 16, and 17; CI Vat Blue 6; and CI Acid Blue 45, and copper phthalocyanine pigments having 1 to 5 phthalimidomethyl groups substituted on the phthalocyanine skeleton. An example of a dye for cyan toner is CI Solvent Blue 70.

[0083] Yellow toner pigments include the following: CI Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 16, 17, 23, 62, 65, 73, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 151, 154, 155, 168, 174, 175, 176, 180, 181, 185; CI Vat Yellow 1, 3, 20. An example of a dye for yellow toner is CI Solvent Yellow 162.

[0084] These colorants may be used alone or in combination, or in the form of a solid solution. The colorant is selected in consideration of hue angle, chroma, brightness, lightfastness, transparency on an overhead projector, and dispersibility in toner. The content of the colorant is preferably 0.1 parts by mass or more and 30.0 parts by mass or less relative to the total amount of the resin components.

[0085] <Inorganic fine particles> The toner preferably contains inorganic fine particles, mainly for the purpose of improving fluidity and chargeability, and the inorganic fine particles are preferably attached to the toner surface.

[0086] As inorganic fine particles serving as spacer particles for improving the releasability between the toner and the carrier, silica particles having a maximum peak particle size of 80 nm to 200 nm based on the number distribution are preferred, and in order to function as spacer particles while better suppressing separation from the toner, the maximum peak particle size based on the number distribution is more preferably 100 nm to 150 nm.

[0087] In order to improve the fluidity of the toner, it is preferable to incorporate inorganic fine particles having a maximum peak particle size of 20 nm or more and 50 nm or less based on the number distribution, and it is also preferable to use them in combination with the silica particles.

[0088] Furthermore, other external additives may be added to the toner particles in order to improve fluidity and transferability. The external additives added to the surface of the toner particles preferably contain inorganic fine particles such as titanium oxide, alumina oxide, and silica, and a plurality of types may be used in combination.

[0089] The total content of the external additives is preferably 0.3 to 5.0 parts by mass, and more preferably 0.8 to 4.0 parts by mass, relative to 100 parts by mass of toner particles. Among these, the content of silica particles having a number distribution-based maximum peak particle size of 80 to 200 nm is 0.1 to 2.5 parts by mass, more preferably 0.5 to 2.0 parts by mass. When the content of silica particles having a number distribution-based maximum peak particle size of 80 to 200 nm is within this range, the effect as spacer particles becomes more pronounced.

[0090] The surfaces of silica particles or inorganic fine particles used as external additives are preferably subjected to a hydrophobic treatment, preferably using a coupling agent such as a titanium coupling agent or a silane coupling agent, a fatty acid or a metal salt thereof, a silicone oil, or a combination thereof.

[0091] Examples of titanium coupling agents include the following: tetrabutyl titanate, tetraoctyl titanate, isopropyl triisostearoyl titanate, isopropyl tridecylbenzenesulfonyl titanate, and bis(dioctyl pyrophosphate)oxyacetate titanate.

[0092] Examples of silane coupling agents include: γ-(2-aminoethyl)aminopropyltrimethoxysilane, γ-(2-aminoethyl)aminopropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-β-(N-vinylbenzylaminoethyl)γ-aminopropyltrimethoxysilane hydrochloride, hexamethyldisilazane, methyltrimethoxysilane, butyltrimethoxysilane, isobutyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, decyltrimethoxysilane, dodecyltrimethoxysilane, phenyltrimethoxysilane, o-methylphenyltrimethoxysilane, and p-methylphenyltrimethoxysilane.

[0093] Examples of fatty acids include long-chain fatty acids such as undecylic acid, lauric acid, tridecylic acid, dodecylic acid, myristic acid, palmitic acid, pentadecylic acid, stearic acid, heptadecylic acid, arachidic acid, montanic acid, oleic acid, linoleic acid, and arachidonic acid. Examples of metals in these fatty acid metal salts include zinc, iron, magnesium, aluminum, calcium, sodium, and lithium.

[0094] Examples of silicone oils include dimethyl silicone oil, methylphenyl silicone oil, and amino-modified silicone oil.

[0095] The hydrophobic treatment is preferably carried out by adding a hydrophobic treatment agent to the particles to be treated in an amount of 1% by mass or more and 30% by mass or less (more preferably 3% by mass or more and 7% by mass or less) relative to the particles to be treated, thereby coating the particles to be treated.

[0096] The degree of hydrophobicity of the hydrophobized external additive is not particularly limited, but for example, the degree of hydrophobicity after the treatment is preferably 40 or more and 98 or less. The degree of hydrophobicity indicates the wettability of the sample with respect to methanol, and is an index of hydrophobicity.

[0097] When the toner of the present invention is mixed with a magnetic carrier to be used as a two-component developer, good results are usually obtained when the carrier mixing ratio is 2% by mass or more and 15% by mass or less, preferably 4% by mass or more and 13% by mass or less, in terms of toner concentration in the developer. If the toner concentration is less than 2% by mass, the image density tends to decrease, and if the toner concentration exceeds 15% by mass, fogging and scattering inside the machine tend to occur.

[0098] In addition, in the case of a replenishment developer to be replenished to a developing device in response to a decrease in the toner concentration of the two-component developer in the developing device, the amount of toner is 2 parts by mass or more and 50 parts by mass or less per 1 part by mass of the replenishment magnetic carrier.

[0099] Next, an example of an image forming apparatus equipped with a developing device that uses the magnetic carrier, two-component developer, and replenishment developer of the present invention will be described, but the developing device used in the developing method of the present invention is not limited to this.

[0100] <Measurement of magnetic carrier resistivity> The resistivity of the magnetic carrier and the porous magnetic core is measured using a measuring device shown in Fig. 4. The resistivity of the magnetic carrier is measured at an electric field strength of 2000 (V / cm). Resistance measurement cell A has a cross-sectional area of ​​2.4 cm 2 The device is composed of a cylindrical container (made of PTFE resin) 17 with holes, a lower electrode (made of stainless steel) 18, a support base (made of PTFE resin) 19, and an upper electrode (made of stainless steel) 20. The cylindrical container 17 is placed on the support base 19, and a sample (magnetic carrier or porous magnetic core) 21 is filled to a thickness of approximately 1 mm. The upper electrode 20 is placed on the filled sample 21, and the thickness of the sample is measured. As shown in Figure 4(a), the gap when there is no sample is d1, and as shown in Figure 4(b), the gap when the sample is filled to a thickness of approximately 1 mm is d2. The sample thickness d can be calculated using the following formula. d = d2 - d1 (mm) At this time, the mass of the sample is appropriately changed so that the thickness d of the sample is 0.95 mm or more and 1.04 mm or less. The resistivity of the sample can be determined by applying a DC voltage between the electrodes and measuring the current that flows at that time. For the measurement, an electrometer 22 (Kesley 6517A, manufactured by Kesley) and a processing computer 23 for control are used. The control system and control software (LabVEIW, National Instruments) manufactured by National Instruments were used as the control processing computer.

[0101] The measurement conditions were: contact area between the sample and the electrode S = 2.4 cm 2 The measured value d is input so that the thickness of the sample is between 0.95 mm and 1.04 mm. The load on the upper electrode is set to 270 g, and the maximum applied voltage is set to 1000 V. Specific resistance (Ω cm) = (applied voltage (V) / measured current (A)) × S (cm2) / d (cm) Electric field strength (V / cm) = applied voltage (V) / d (cm) The resistivity of the magnetic carrier and the porous magnetic core at the electric field strength is read from the graph as the resistivity at the electric field strength on the graph.

[0102] <Method for measuring the 50% diameter (D50) of a magnetic carrier or porous magnetic core based on volume> The particle size distribution was measured using a laser diffraction / scattering particle size distribution measuring device "Microtrac MT3300EX" (manufactured by Nikkiso Co., Ltd.). The 50% diameter (D50) on a volume basis of the magnetic carrier and porous magnetic core was measured using a sample supply device for dry measurement, the "One-Shot Dry Sample Conditioner Turbotrac" (manufactured by Nikkiso Co., Ltd.). The supply conditions for the Turbotrac were a dust collector used as the vacuum source, with an air volume of approximately 33 l / sec and a pressure of approximately 17 kPa. Control is performed automatically on the software. The particle size is calculated as the 50% particle size (D50), which is the cumulative value of the volume distribution. Control and analysis are performed using the accompanying software (version 10.3.3-202D). The measurement conditions are as follows: SetZero time: 10 seconds Measurement time: 10 seconds Number of measurements: 1 Particle refractive index: 1.81% Particle shape: non-spherical Upper limit of measurement: 1408 μm Measurement lower limit: 0.243μm Measurement environment: 23°C, 50% RH

[0103] <Measurement of pore diameter and pore volume of porous magnetic core> The pore size distribution of the porous magnetic core is measured by mercury intrusion porosimetry. The measurement principle is as follows. In this measurement, the pressure applied to the mercury is varied, and the amount of mercury that penetrates into the pores is measured. The conditions under which mercury can penetrate into the pores can be expressed from the balance of forces as PD = -4σCOSθ, where P is the pressure, D is the pore diameter, θ is the contact angle of the mercury, and σ is the surface tension. If the contact angle and surface tension are constants, then the pressure P and the pore diameter D into which mercury can penetrate at that time are inversely proportional. For this reason, the pressure P and the amount of infiltrated liquid V at that time are measured by varying the pressure, and the horizontal axis P of the PV curve, obtained by this measurement, is then directly substituted for the pore diameter in this equation to determine the pore distribution.

[0104] Measurement can be performed using a measuring device such as a fully automatic multi-function mercury porosimeter PoreMaster series or PoreMaster-GT series manufactured by Yuasa Ionics Co., Ltd., or an automatic porosimeter Autopore IV 9500 series manufactured by Shimadzu Corporation.

[0105] Specifically, the measurement was carried out using an Autopore IV9520 manufactured by Shimadzu Corporation under the following conditions and procedures. Measurement conditions Measurement environment: 20℃ Measurement cell sample volume 5cm 3 , indentation volume 1.1cm 3 , Application for powder Measurement range: 2.0 psia (13.8 kPa) or more and 59989.6 psia (413.7 kPa) or less Measurement steps: 80 steps (When the pore diameter is calculated logarithmically, the steps are spaced at equal intervals.) Pressurization parameters: Exhaust pressure 50μmHg Exhaust time 5.0 min Mercury injection pressure 2.0 psia (13.8 kPa) Equilibrium time 5secs High pressure parameters Equilibration time 5secs Mercury parameters Advancing contact angle 130.0 degrees Receding contact angle 130.0degrees Surface tension 485.0mN / m(485.0dynes / cm) Mercury density 13.5335g / mL

[0106] Measurement procedure (1) Approximately 1.0 g of the porous magnetic core is weighed and placed in the sample cell. Enter the weighing value. (2) In the low-pressure section, measure the range of 2.0 psia (13.8 kPa) to 45.8 psia (315.6 kPa). (3) In the high-pressure section, the range measured was between 45.9 psia (316.3 kPa) and 59,989.6 psia (413.6 MPa). (4) The pore size distribution is calculated from the mercury injection pressure and the amount of mercury injected. (2), (3), and (4) were performed automatically using the software provided with the device. From the pore size distribution measured as described above, the pore size at which the differential pore volume is maximum in the pore size range of 0.1 μm to 3.0 μm is read, and this is taken as the pore size at which the differential pore volume is maximum. In addition, the pore volume obtained by integrating the differential pore volume in the pore diameter range of 0.1 μm to 3.0 μm was calculated using the attached software.

[0107] <Measuring method for weight average particle size (D4) and number average particle size (D1)> The weight-average particle size (D4) and number-average particle size (D1) of the toner were measured using a precision particle size distribution measuring device, "Coulter Counter Multisizer 3" (registered trademark, manufactured by Beckman Coulter, Inc.), equipped with a 100 μm aperture tube and employing the narrow-pore electrical resistance method, and the accompanying dedicated software, "Beckman Coulter Multisizer 3 Version 3.51" (manufactured by Beckman Coulter, Inc.), for setting measurement conditions and analyzing measurement data. Measurements were made with an effective number of 25,000 measurement channels, and the measurement data was analyzed and calculated. The aqueous electrolyte solution used for the measurement is prepared by dissolving special grade sodium chloride in ion-exchanged water to a concentration of approximately 1% by mass, such as "ISOTON II" (manufactured by Beckman Coulter).

[0108] Before carrying out the measurements and analysis, the dedicated software was set up as follows. In the "Change Standard Measurement Method (SOM)" screen of the dedicated software, set the total count in control mode to 50,000 particles, the number of measurements to 1, and the Kd value obtained using "Standard Particles 10.0 μm" (Beckman Coulter). Press the threshold / noise level measurement button to automatically set the threshold and noise level. Also, set the current to 1600 μA, the gain to 2, the electrolyte to ISOTON II, and check "Flush aperture tube after measurement." In the dedicated software's "Pulse to particle size conversion setting screen," set the bin interval to logarithmic particle size, the particle size bin to 256 particle size bins, and the particle size range from 2 μm to 60 μm.

[0109] The specific measurement method is as follows. (1) Pour approximately 200 ml of the electrolyte solution into a 250 ml round-bottom glass beaker made specifically for the Multisizer 3, set it on the sample stand, and stir the stirrer rod counterclockwise at 24 revolutions per second. Then, use the "aperture flush" function of the analysis software to remove any dirt or air bubbles from inside the aperture tube. (2) Approximately 30 ml of the electrolyte solution is placed in a 100 ml flat-bottom glass beaker. A 10% by weight aqueous solution of "Contaminon N" (a neutral detergent for cleaning precision measuring instruments, pH 7, consisting of a nonionic surfactant, anionic surfactant, and organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) is added as a dispersant. Add approximately 0.3 ml of a diluted solution prepared by diluting 100% ethanol (manufactured by Epson) with ion-exchanged water three times by mass. (3) A predetermined amount of ion-exchanged water is placed in the water tank of an ultrasonic disperser, "Ultrasonic Dispension System Tetora 150" (manufactured by Nikkaki Bios Co., Ltd.), which has two built-in oscillators with an oscillation frequency of 50 kHz and a phase difference of 180 degrees and an electrical output of 120 W. Approximately 2 ml of the Contaminon N is added to this water tank. (4) Set the beaker (2) in the beaker fixing hole of the ultrasonic disperser, operate the ultrasonic disperser, and adjust the height of the beaker so that the resonance state of the liquid surface of the electrolytic solution in the beaker is maximized. (5) While the electrolyte solution in the beaker in (4) is irradiated with ultrasonic waves, approximately 10 mg of toner is added little by little to the electrolyte solution and dispersed. The ultrasonic dispersion process is then continued for another 60 seconds. During the ultrasonic dispersion, the water temperature in the water tank is appropriately adjusted to be between 10°C and 40°C. (6) Using a pipette, add the electrolyte solution (5) containing the dispersed toner to the round-bottom beaker (1) placed in the sample stand, and adjust the measurement concentration to approximately 5%. Then, measure the particle count until it reaches 50,000 particles. (7) The measurement data is analyzed using the dedicated software provided with the device to calculate the weight average particle size (D4) and number average particle size (D1). Note that when the dedicated software is set to Graph / Volume %, the "Average diameter" on the Analysis / Volume Statistics (Arithmetic Mean) screen is the weight average particle size (D4), and when the dedicated software is set to Graph / Number %, the "Average diameter" on the Analysis / Number Statistics (Arithmetic Mean) screen is the number average particle size (D1).

[0110] <Calculation method for the amount of fine powder> The amount of fine powder (number %) in the toner is calculated as follows. For example, to determine the percentage of particles 4.0 μm or smaller in a toner, after performing the measurement using the Multisizer 3 mentioned above, (1) set the dedicated software to Graph / Number% and display the measurement results chart as a percentage of the number. (2) Check the "<" in the particle size setting section on the Format / Particle Size / Particle Size Statistics screen and enter "4" in the particle size input section below. Then, (3) when the Analysis / Number Statistics (Arithmetic Mean) screen is displayed, the value in the "<4 μm" display section is the percentage of particles 4.0 μm or smaller in the toner.

[0111] <How to calculate the amount of coarse powder> The amount of coarse particles (vol %) on a volume basis in the toner is calculated as follows. For example, to determine the volume percentage of particles 10.0 μm or larger in a toner, after performing the measurement using the Multisizer 3 mentioned above, (1) set the dedicated software to Graph / Volume% and display the measurement results chart as a volume percentage. (2) Check the ">" in the particle size setting section on the Format / Particle Size / Particle Size Statistics screen and enter "10" in the particle size input section below. Then, (3) when the Analysis / Volume Statistics (Arithmetic Mean) screen is displayed, the value in the ">10 μm" display section is the volume percentage of particles 10.0 μm or larger in the toner.

[0112] <Powder X-ray diffraction analysis> The XRD pattern was measured using an X-ray diffraction analyzer (X'pert PRO-MPD: manufactured by PANalytical). X-rays were generated at an accelerating voltage of 45 kV and a current of 40 mA. The powder X-ray measurement conditions are: Divergence slit: 1 / 4rad (fixed) Anti-scatter slit: 1 / 2rad Soller slit: 0.04rad Mask: 15mm Anti-scatter slit: 7.5mm Spinner: Yes Measurement method Scan axis: Continuous 2θ / θ Measurement range: 5.0°≦2θ≦80° Step interval: 0.026deg / s Scan speed: 0.525deg / s Measurements were carried out. The sample used to measure P70 was prepared using the same formula as the porous ferrite core material, and by changing the oxygen concentration in the firing process during manufacturing, the magnetization strength when an external magnetic field of 5000 / 4π (kA / m) was applied was measured to be 70Am. 2 Particles adjusted to give a density of 1 / kg are used.

[0113] <Method for measuring the magnetization strength of a magnetic core> The magnetization strength of the magnetic core can be measured using a vibrating sample magnetometer or a direct current magnetization characteristic recorder (BH tracer). In the examples described below, the magnetization strength is measured using a vibrating sample magnetometer BHV-30 (manufactured by Riken Denshi Co., Ltd.) according to the following procedure. The sample is a cylindrical plastic container packed with magnetic cores. The actual mass of the sample packed in the container is measured. The sample is then glued in place inside the plastic container with instant adhesive to prevent it from moving. Using a standard sample, the external magnetic field axis and the magnetization moment axis are calibrated at 5000 / 4π (kA / m). The strength of magnetization was measured from the loop of the magnetization moment when an external magnetic field of 5000 / 4π (kA / m) was applied at a sweep speed of 5 (min / roop). From this, the strength of magnetization of the magnetic core (Am 2 / kg).

[0114] <Toner manufacturing method> The method for producing toner particles is not particularly limited, but a pulverization method is preferred from the viewpoint of dispersing the release agent and the polymer in which a styrene-acrylic polymer is graft-polymerized onto a polyolefin. The reason for this is that when toner particles are produced in an aqueous medium, the highly hydrophobic release agent and the polymer in which a styrene-acrylic polymer (styrene-acrylic resin) is graft-polymerized onto a polyolefin tend to be localized inside the toner particles. This makes it difficult to form a core-shell structure using the heat treatment device described above.

[0115] The procedure for producing toner by the pulverization method will be described below. In the raw material mixing process, predetermined amounts of materials constituting the toner particles, such as binder resin, release agent, colorant, crystalline polyester, and optionally other components such as charge control agent, are weighed, blended, and mixed. Examples of mixing devices include a double cone mixer, a V-type mixer, a drum mixer, a super mixer, a Henschel mixer, a Nauta mixer, and a Mechano Hybrid (manufactured by Nippon Coke and Engineering Co., Ltd.).

[0116] Next, the mixed materials are melt-kneaded to disperse the wax and other components in the binder resin. In this melt-kneading process, a batch kneader such as a pressure kneader or a Banbury mixer, or a continuous kneader can be used. Single- or twin-screw extruders are commonly used due to their advantage of continuous production. Examples include a KTK twin-screw extruder (manufactured by Kobe Steel, Ltd.), a TEM twin-screw extruder (manufactured by Toshiba Machine Co., Ltd.), a PCM kneader (manufactured by Ikegai Iron Works), a twin-screw extruder (manufactured by KCK Corporation), a Co-Kneader (manufactured by Buss Co., Ltd.), and a Kneadex (manufactured by Nippon Coke and Engineering Co., Ltd.). Furthermore, the resin composition obtained by melt-kneading may be rolled using a twin roll or the like and cooled with water or the like in a cooling process.

[0117] The cooled resin composition is then pulverized to a desired particle size in a pulverization step, which involves coarse pulverization using a pulverizer such as a crusher, hammer mill, or feather mill, followed by further pulverization using a pulverizer such as a Kryptron System (Kawasaki Heavy Industries), a Super Rotor (Nisshin Engineering), a Turbo Mill (Turbo Kogyo), or an air jet pulverizer.

[0118] Thereafter, as necessary, the mixture is classified using a classifier or sieve such as an inertial classification type Elbow Jet (manufactured by Nittetsu Mining Co., Ltd.), a centrifugal classification type Turboplex (manufactured by Hosokawa Micron Corporation), a TSP Separator (manufactured by Hosokawa Micron Corporation), or a Faculty (manufactured by Hosokawa Micron Corporation).

[0119] Thereafter, the toner particles are subjected to a surface treatment by heating to increase the circularity of the toner. For example, the surface treatment can be performed by using a surface treatment device shown in FIG. 1 with hot air. The mixture supplied by the material supply means 101 is introduced into an introduction pipe 103, which is installed vertically to the material supply means, by compressed gas adjusted by a compressed gas adjustment means 102. The mixture that passes through the introduction pipe is uniformly dispersed by a conical protruding member 104 installed in the center of the material supply means, and is then introduced into eight-way supply pipes 105 that radiate outward, and into a treatment chamber 106 where heat treatment is carried out. At this time, the flow of the mixture supplied to the processing chamber is regulated by a regulating means 109 for regulating the flow of the mixture, which is provided in the processing chamber. Therefore, the mixture supplied to the processing chamber is heat-treated while swirling in the processing chamber, and then cooled.

[0120] Hot air for heat-treating the supplied mixture is supplied from hot air supply means 107, and is introduced into the treatment chamber by spirally swirling it using a swirling member 113 for swirling the hot air. The swirling member 113 for swirling the hot air has a plurality of blades, and the swirling of the hot air can be controlled by adjusting the number and angle of the blades. The hot air supplied into the treatment chamber preferably has a temperature of 100°C to 300°C at the outlet of the hot air supply means 107. If the temperature at the outlet of the hot air supply means is within the above range, it is possible to uniformly spheronize the toner particles while preventing fusion and coalescence of the toner particles due to excessive heating of the mixture.

[0121] The heat-treated toner particles are then cooled by cold air supplied from cold air supplying means 108-1, 108-2, and 108-3, and the temperature of the cold air supplied from the cold air supplying means 108-1, 108-2, and 108-3 is preferably -20°C to 30°C. If the temperature of the cold air is within the above range, the heat-treated toner particles can be efficiently cooled, and fusion and coalescence of the heat-treated toner particles can be prevented without impeding the uniform spheroidization of the mixture. The absolute moisture content of the cold air is 0.5 g / m 3 More than 15.0g / m3 It is preferable that:

[0122] Next, the cooled heat-treated toner particles are collected by collection means 110 at the bottom end of the processing chamber. A blower (not shown) is provided ahead of the collection means, and the toner particles are sucked and transported by the blower. Furthermore, the powder particle supply port 114 is positioned so that the swirling direction of the supplied mixture and the swirling direction of the hot air are the same, and the recovery means 110 of the surface treatment device is positioned on the outer periphery of the treatment chamber so as to maintain the swirling direction of the swirled powder particles. Furthermore, the cold air supplied from the cold air supply means 8 is configured to be supplied horizontally and tangentially from the outer periphery of the device to the circumferential surface inside the treatment chamber. The swirling directions of the toner supplied from the powder supply port, the cold air supplied from the cold air supply means, and the hot air supplied from the hot air supply means are all the same. This prevents turbulence within the treatment chamber, strengthens the swirling flow within the device, applies a strong centrifugal force to the toner, and further improves toner dispersibility, resulting in toner with fewer coalesced particles and a uniform shape.

[0123] When the average circularity of the toner is 0.960 or more and 0.980 or less, the non-electrostatic adhesion can be kept low, which is preferable from the viewpoint of fogging.

[0124] The toner is then divided into two halves, one fine and one coarse. For example, an inertial classification system, Elbow Jet (manufactured by Nittetsu Mining Co., Ltd.), is used to separate the two halves. A desired amount of silica fine particles A is then externally added to the surface of each of the two heat-treated toner particles. Examples of methods for externally adding silica fine particles include a double cone mixer, V-type mixer, drum mixer, super mixer, Henschel mixer, Nauta mixer, Mechano Hybrid (manufactured by Nippon Coke & Engineering Co., Ltd.), and Nobilta (manufactured by Hosokawa Micron Corporation), and these are used to stir and mix the particles. If necessary, external additives other than silica fine particles, such as a fluidizing agent, may also be added. The methods for measuring various physical properties of the toner and raw materials are described below. [Example]

[0125] <Production example of porous magnetic core particles> Process 1 (weighing and mixing process) Fe2O361.7% by mass MnCO334.2% by mass Mg(OH)23.0% by mass SrCO31.1% by mass The ferrite raw material was weighed so that Thereafter, the mixture was ground and mixed for 2 hours in a dry ball mill using zirconia balls (φ10 mm).

[0126] Process 2 (pre-firing process) After crushing and mixing, the mixture was fired in air at 950°C for 2 hours in a burner-type firing furnace to produce calcined ferrite. The composition of the ferrite was as follows: (MnO)a(MgO)b(SrO)c(Fe2O3)d In the above formula, a=0.40, b=0.07, c=0.01, and d=0.52.

[0127] Process 3 (crushing process) The calcined ferrite was crushed to about 0.5 mm using a crusher, and then 30 parts by mass of water was added to 100 parts by mass of the calcined ferrite using zirconia balls (φ1.0 mm) and crushed for 2 hours in a wet ball mill. After separating the balls, the mixture was crushed for 3 hours using zirconia beads (φ1.0 mm) in a wet bead mill to obtain a ferrite slurry.

[0128] Process 4 (granulation process) To the ferrite slurry, 2.0 parts by mass of polyvinyl alcohol was added as a binder per 100 parts by mass of the calcined ferrite, and the mixture was granulated into 40 μm spherical particles using a spray dryer (manufacturer: Okawahara Kakoki).

[0129] Step 5 (baking process) In order to control the firing atmosphere, the spherical particles were fired in an electric furnace under a nitrogen atmosphere (oxygen concentration 1.0% by volume) at 1150°C for 4 hours.

[0130] Process 6 (sorting process) After the aggregated particles were crushed, the particles were sieved through a sieve with 250 μm openings to remove coarse particles, yielding porous magnetic core particles, designated as Magnetic Core 1. The physical properties of the obtained Magnetic Core 1 are shown in Table 1.

[0131] Process 7 (resin filling process) 100.0 parts by mass of magnetic core 1 were placed in the stirring vessel of a mixer / stirrer (Dalton Corporation, universal stirrer, NDMV type). While maintaining the temperature at 60°C, nitrogen was introduced while reducing the pressure to 2.3 kPa. The silicone resin solution was added dropwise under reduced pressure to a resin content of 7.5 parts by mass relative to magnetic core 1. Stirring was continued for 2 hours after the completion of the dropwise addition. The temperature was then raised to 70°C, the solvent was removed under reduced pressure, and the silicone resin composition obtained from the silicone resin solution was filled into the magnetic core 1 particles. After cooling, the resulting filled magnetic core particles were transferred to a mixer (Sugiyama Heavy Industries, Ltd., UD-AT type drum mixer) equipped with spiral blades in a rotatable mixing vessel. The mixture was heated to 220°C at a heating rate of 2°C / min under a nitrogen atmosphere and atmospheric pressure. The mixture was heated and stirred at this temperature for 60 minutes to harden the resin. After heat treatment, low magnetic force products were separated by magnetic separation and classified using a 150 μm sieve to obtain magnetic core 2. The physical properties of the magnetic core 2 thus obtained are shown in Table 1.

[0132] <Example of manufacturing ferrite core particles> Process 1 (weighing and mixing process) Fe2O361.7% by mass MnCO334.2% by mass Mg(OH)23.0% by mass SrCO31.1% by mass The ferrite raw material was weighed so that Thereafter, the mixture was ground and mixed for 2 hours in a dry ball mill using zirconia balls (φ10 mm).

[0133] Process 2 (pre-firing process) After crushing and mixing, the mixture was fired in air at 1000°C for 2 hours in a burner-type firing furnace to produce calcined ferrite. The composition of the ferrite was as follows: (MnO)a(MgO)b(SrO)c(Fe2O3)d In the above formula, a=0.40, b=0.07, c=0.01, and d=0.52.

[0134] Process 3 (crushing process) The calcined ferrite was crushed to about 0.5 mm using a crusher, and then 30 parts by mass of water was added to 100 parts by mass of the calcined ferrite using stainless steel balls (φ1.0 mm), and the mixture was crushed in a wet ball mill for 2 hours. After the balls were separated, the mixture was crushed in a wet bead mill using stainless steel balls (φ1.0 mm) for 3 hours to obtain a ferrite slurry.

[0135] Process 4 (granulation process) To the ferrite slurry, 2.0 parts by mass of polyvinyl alcohol was added as a binder per 100 parts by mass of the calcined ferrite, and the mixture was granulated into 45 μm spherical particles using a spray dryer (manufacturer: Okawahara Kakoki).

[0136] Step 5 (baking process) In order to control the firing atmosphere, the spherical particles were fired in an electric furnace under a nitrogen atmosphere (oxygen concentration 0.6% by volume) at 1200°C for 6 hours.

[0137] Process 6 (sorting process) After the aggregated particles were crushed, the particles were sieved through a sieve with 250 μm openings to remove coarse particles, thereby obtaining ferrite core particles, which are designated as magnetic core 3. The physical properties of the obtained magnetic core 3 are shown in Table 1.

[0138] <Production example of magnetic material dispersed resin core particles> Magnetite fine particles (spherical, number average particle size 250 nm, saturation magnetization 50 (Am 2 / kg), residual magnetization 4.2 (Am 2 / kg), coercive force 4.4 (kA / m), resistivity at 1000 (V / cm) 3.3 x 10 6(Ω·cm)) and a silane coupling agent (3-(2-aminoethylaminopropyl)trimethoxysilane) (in an amount of 3.0 mass% relative to the mass of the magnetite microparticles) were introduced into the vessel. Then, the mixture was mixed and stirred at high speed at a temperature of 100°C or higher in the vessel to surface treat the magnetite microparticles. Phenol 10 parts by mass Formaldehyde solution (37% formaldehyde aqueous solution) 16 parts by weight 84 parts by mass of the above surface-treated magnetite particles The above materials were introduced into a reactor and mixed thoroughly at a temperature of 40°C. The mixture was then heated to 85°C at an average heating rate of 3°C / min while stirring, and 4 parts by mass of 28% ammonia water and 25 parts by mass of water were added to the reactor. The temperature was maintained at 85°C, and the mixture was polymerized and cured for 3 hours. The peripheral speed of the stirring blade was 1.8 m / sec. After the polymerization reaction, the mixture was cooled to 30°C and water was added. The supernatant was removed, and the resulting precipitate was washed with water and air-dried. The air-dried product was dried under reduced pressure (5 hPa or less) at 60°C to obtain magnetic material-dispersed resin core particles. These were designated magnetic cores 4. The physical properties of the magnetic core 4 thus obtained are shown in Table 1.

[0139] [Table 1]

[0140] <Production example of resin A1> 95.2% by mass of the silicone-containing acrylic monomer corresponding to unit Y1 shown below and 4.8% by mass of the monomer corresponding to unit Y2 were added to a four-neck flask equipped with a reflux condenser, a thermometer, a nitrogen inlet tube, and a rotary stirrer. The structures of unit Y1 and unit Y2 are shown in Table 2. Furthermore, 100 parts by mass of toluene, 100 parts by mass of methyl ethyl ketone, and 2.0 parts by mass of azobisisovaleronitrile were added to 106 parts by mass of the above monomer mixture. The resulting mixture was maintained at 70°C for 10 hours under a nitrogen stream, and after the polymerization reaction was completed, washing was repeated to obtain a resin A1 solution (solid content 35% by mass). The l + m value of this solution calculated by gel permeation chromatography (GPC) was 70.

[0141] <Manufacturing Examples of Resins A2 to A26> Resins A2 to A26 were obtained in the same manner as in the production of Resin A1, except that the structures of Units Y1 and Y2 and the values ​​of a, b, n, and l+m were changed as shown in Tables 2-1 and 2-2.

[0142] [Table 2-1]

[0143] [Table 2-2]

[0144] <Method for producing macromonomers> The macromonomer used in Resin B can be synthesized, for example, by the following method. The raw materials shown below were added to a four-neck flask equipped with a reflux condenser, thermometer, nitrogen inlet, and ground-floor stirrer. Methacrylic acid chloride 1.7% by mass Polymethyl methacrylate (Mw: approximately 5000) with a hydroxyl group at one end: 98.3% by mass Furthermore, 100 parts by mass of THF and 1.0 part by mass of 4-tert-butylcatechol were added to 100 parts by mass of the above monomer mixture, and the mixture was heated under reflux for 5 hours under a nitrogen stream. After the reaction was completed, the mixture was washed with sodium bicarbonate to obtain a solution of methacrylic acid macromonomer.

[0145] <Method of manufacturing resin B1> The monomers indicated below were added to a four-neck flask equipped with a reflux condenser, thermometer, nitrogen inlet, and ground-gravity stirrer. Cyclohexyl methacrylate 74.5% by mass Methyl methacrylate 0.5% by mass Methacrylic acid macromonomer 25% by mass Furthermore, 100 parts by mass of toluene, 100 parts by mass of methyl ethyl ketone, and 2.0 parts by mass of azobisisovaleronitrile were added to 106 parts by mass of the above monomer mixture. The resulting mixture was maintained at 70°C for 10 hours under a nitrogen stream, and after the polymerization reaction was completed, washing was repeated to obtain a resin B1 solution (solid content 35% by mass). The weight average molecular weight of this solution measured by gel permeation chromatography (GPC) was 57,000. The SPb was 10.2.

[0146] <Method of manufacturing resin B2> The monomers indicated below were added to a four-neck flask equipped with a reflux condenser, thermometer, nitrogen inlet, and ground-gravity stirrer. Cyclohexyl methacrylate 74.5% by mass Methyl methacrylate 25.5% by mass Furthermore, 100 parts by mass of toluene, 100 parts by mass of methyl ethyl ketone, and 2.0 parts by mass of azobisisovaleronitrile were added to 106 parts by mass of the above monomer mixture. The resulting mixture was maintained at 70°C for 10 hours under a nitrogen stream. After the polymerization reaction was completed, the mixture was repeatedly washed to obtain a resin B2 solution (solid content 35% by mass). The weight average molecular weight of this solution measured by gel permeation chromatography (GPC) was 68,000. The SPb was 10.2.

[0147] <Method of manufacturing resin B3> The monomers indicated below were added to a four-neck flask equipped with a reflux condenser, thermometer, nitrogen inlet, and ground-gravity stirrer. Methyl methacrylate 75% by mass Methacrylic acid macromonomer 25% by mass Furthermore, 100 parts by mass of toluene, 100 parts by mass of methyl ethyl ketone, and 2.0 parts by mass of azobisisovaleronitrile were added to 106 parts by mass of the above monomer mixture. The resulting mixture was maintained at 70°C for 10 hours under a nitrogen stream. After the polymerization reaction was completed, washing was repeated to obtain a resin B3 solution (solid content 35% by mass). The weight average molecular weight of this solution measured by gel permeation chromatography (GPC) was 35,000. The SPb was 9.9.

[0148] <Manufacturing method of resin B4> The monomers indicated below were added to a four-neck flask equipped with a reflux condenser, thermometer, nitrogen inlet, and ground-gravity stirrer. Cyclohexyl methacrylate 30% by mass Methyl methacrylate 45% by mass Methacrylic acid macromonomer 25% by mass Furthermore, 100 parts by mass of toluene, 100 parts by mass of methyl ethyl ketone, and 2.0 parts by mass of azobisisovaleronitrile were added to 106 parts by mass of the above monomer mixture. The resulting mixture was maintained at 70°C for 10 hours under a nitrogen stream. After the polymerization reaction was completed, the mixture was repeatedly washed to obtain a resin B4 solution (solid content 35% by mass). The weight average molecular weight of this solution measured by gel permeation chromatography (GPC) was 36,000. The SPb was 10.1.

[0149] <Manufacturing method of resin B5> The monomers indicated below were added to a four-neck flask equipped with a reflux condenser, thermometer, nitrogen inlet, and ground-gravity stirrer. Hexyl methacrylate 100% by mass Furthermore, 100 parts by mass of toluene, 100 parts by mass of methyl ethyl ketone, and 2.0 parts by mass of azobisisovaleronitrile were added to 106 parts by mass of the above monomer mixture. The resulting mixture was maintained at 70°C for 10 hours under a nitrogen stream. After the polymerization reaction was completed, the mixture was repeatedly washed to obtain a resin B5 solution (solid content 35% by mass). The weight average molecular weight of this solution measured by gel permeation chromatography (GPC) was 48,000. The SPb was 9.3.

[0150] <Manufacturing method of resin B6> The monomers indicated below were added to a four-neck flask equipped with a reflux condenser, thermometer, nitrogen inlet, and ground-gravity stirrer. 2-Hydroxyethyl methacrylate 35.4% by mass Methyl methacrylate 64.6% by mass Furthermore, 100 parts by mass of toluene, 100 parts by mass of methyl ethyl ketone, and 2.0 parts by mass of azobisisovaleronitrile were added to 106 parts by mass of the above monomer mixture. The resulting mixture was maintained at 70°C for 10 hours under a nitrogen stream. After the polymerization reaction was completed, the mixture was repeatedly washed to obtain a resin B6 solution (solid content 35% by mass). The weight average molecular weight of this solution measured by gel permeation chromatography (GPC) was 37,000. The SPb was 11.4.

[0151] <Manufacturing method of resin B7> The monomers indicated below were added to a four-neck flask equipped with a reflux condenser, thermometer, nitrogen inlet, and ground-gravity stirrer. Polydimethylsiloxane (average degree of polymerization 55) 5.0 parts by mass Methyltrichlorosilane 25.0 parts by mass ·Water 40.0 parts by mass Methyl isobutyl ketone 30.0 parts by mass Of the above materials, water and methyl isobutyl ketone were placed in a reaction vessel equipped with a reflux condenser, a dropping funnel, and a stirrer, and stirred vigorously to prevent the formation of a two-layer mixture. Polydimethylsiloxane was added, and the mixture was further stirred and placed in an ice bath. When the temperature of the mixture in the reaction vessel reached 10°C, methyltrichlorosilane was added dropwise. After the addition was complete, the mixture was washed and the solvent was distilled off under reduced pressure to obtain Resin B7. The SPb was 10.2.

[0152] <Manufacturing method of resin B8> The monomers indicated below were added to a four-neck flask equipped with a reflux condenser, thermometer, nitrogen inlet, and ground-gravity stirrer. Hexyl methacrylate 10.0% by mass Norbornene 90.0% by mass Furthermore, 100 parts by mass of toluene, 100 parts by mass of methyl ethyl ketone, and 2 parts by mass of bis(dibenzylideneacetone)palladium were added to 106 parts by mass of the above monomer mixture. The resulting mixture was maintained at 70°C for 10 hours under a nitrogen stream. After the polymerization reaction was completed, washing was repeated to obtain a resin B8 solution (solid content 35% by mass). The weight-average molecular weight of this solution measured by gel permeation chromatography (GPC) was 37,000. The SPb was 12.0.

[0153] <Resin coating process> -Magnetic carrier 1 manufacturing method Using the magnetic core 1 shown in Table 1, a resin solution containing Resin A and Resin B shown in Table 3 was added to a planetary mixer (Nauta Mixer VN, manufactured by Hosokawa Micron Corporation) maintained under reduced pressure (1.5 kPa) at a temperature of 60°C, so that the solid content of the resin component was 2.0 parts by mass per 100 parts by mass of the magnetic core. The resin solution was added in an amount of 1 / 3, and the solvent was removed and applied for 20 minutes. Next, another 1 / 3 of the resin solution was added, and the solvent was removed and applied for 20 minutes. Another 1 / 3 of the resin solution was then added, and the solvent was removed and applied for 20 minutes. Finally, another 1 / 3 of the resin solution was added, and the solvent was removed and applied for 20 minutes. The magnetic carrier coated with the coating resin composition was then transferred to a mixer (Sugiyama Heavy Industries Co., Ltd., Model UD-AT drum mixer) equipped with spiral blades in a rotatable mixing container. The mixing container was stirred at 10 revolutions per minute, and heat-treated at 120°C for 2 hours in a nitrogen atmosphere. The resulting magnetic carrier 1 was separated by magnetic separation to separate out low-magnetic-force particles, which were passed through a sieve with 150 μm openings and then classified using an air classifier. Magnetic carrier 1 with a volume-based 50% particle size (D50) of 39.1 μm was obtained. The results of the surface analysis of the obtained magnetic carrier 1 are shown in Table 3.

[0154] ·Magnetic Carrier 2-40 Production Method In the method for producing the above magnetic carrier 1, the magnetic core and resin A and resin B of the coating resin solution were changed to those shown in Table 3 to obtain magnetic carriers 2 to 40. The physical properties are shown in Table 3.

[0155] [Table 3]

[0156] <Toner 1 manufacturing example> Polyester resin 100 parts by weight Fischer-Tropsch wax (maximum endothermic peak temperature 90°C) 4 parts by mass 0.3 parts by mass of 3,5-di-t-butylsalicylic acid aluminum compound (Bontron E88, manufactured by Orient Chemical Industries, Ltd.) Carbon black 10 parts by mass The above materials were mixed using a Henschel mixer (FM-75, manufactured by Mitsui Mining Co., Ltd.) at a rotation speed of 1500 rpm for 5 minutes, and then kneaded in a twin-screw kneader (PCM-30, manufactured by Ikegai Corporation) set at a temperature of 130°C. The resulting kneaded mixture was cooled and coarsely pulverized to 1 mm or less using a hammer mill to obtain a coarsely pulverized product. The coarsely pulverized product was then finely pulverized using a mechanical pulverizer (T-250, manufactured by Turbo Kogyo Co., Ltd.). Further, classification was performed using a Faculty (F-300, manufactured by Hosokawa Micron Corporation) to obtain toner base particles 1. The operating conditions were a classifying rotor rotation speed of 11000 rpm and a dispersing rotor rotation speed of 7200 rpm.

[0157] Toner base particles 1 100 parts by mass Silica fine particles A (number average particle size (D1) is 120 nm) 2.0 parts by mass The raw materials shown in the above recipe were mixed using a Henschel mixer (FM-10C, manufactured by Mitsui Mining Co., Ltd.) at a rotation speed of 1900 rpm for a rotation time of 3 minutes, and then heat-treated using the surface treatment device shown in Figure 1 to obtain heat-treated toner particles 1. The operating conditions were feed rate = 5 kg / hr, hot air temperature C = 160°C, and hot air flow rate = 6 m 3 / min., cold air temperature E=-5℃, cold air flow rate=4m 3 / min., Blower air volume = 20m 3 / min., injection air flow rate = 1m 3 / min. The obtained heat-treated toner particles 1 were adjusted using an inertial classification system Elbow Jet (manufactured by Nittetsu Mining Co., Ltd.) so that uniform heat-treated toner particles 1 were obtained. Heat-treated toner particles 1 100 parts by mass Silica fine particles B (number average particle size (D1) is 20 nm) 0.6 parts by mass The above materials were mixed in a Henschel mixer (FM-75 model, manufactured by Mitsui Miike Chemical Engineering Co., Ltd.) at a rotation speed of 1900 rpm for a rotation time of 3 minutes to obtain Toner 1.

[0158] Example 1 9 parts by mass of toner 1 was added to 91 parts by mass of magnetic carrier 1, and the mixture was shaken in a shaker (YS-8D model, manufactured by Yayoi Co., Ltd.) to prepare 300 g of two-component developer 1. The vibration conditions of the shaker were 150 rpm and 2 minutes. Separately, 90 parts by mass of toner 1 was added to 10 parts by mass of magnetic carrier 1, and mixed for 5 minutes in a V-type mixer in an environment of room temperature and humidity 23° C. / 50% RH to obtain replenishment developer 1.

[0159] The two-component developer 1 and the replenishment developer 1 were used to carry out the following evaluations. The image forming apparatus used was a modified Canon imageRUNNER ADVANCE C5560 color copying machine. A two-component developer was placed in each color developing device, and a replenishment developer container containing a replenishment developer for each color was set, and an image was formed, and various evaluations were made before and after the durability test. For durability testing, a chart with FFH output and an image ratio of 1% was used in a printing environment of 23°C temperature and 5% RH (hereafter referred to as "N / L"). A chart with FFH output and an image ratio of 40% was also used in a printing environment of 30°C temperature and 80% RH (hereafter referred to as "H / H"). FFH is the hexadecimal representation of 256 gradations, with 00h being the first gradation (white background) of the 256 gradations and FFH being the 256th gradation (solid area) of the 256 gradations. The number of images output was changed depending on each evaluation item. conditions: Paper: Laser beam printer paper CS-814 (81.4 g / m 2 ) (Canon Marketing Japan Inc.) The printer was modified to enable an image formation speed of 80 sheets / min in full color, A4 size. Development conditions: The development contrast was adjusted to any value, and the automatic correction by the main unit was disabled. The peak-to-peak voltage (Vpp) of the alternating electric field was adjusted to a frequency of 2.0 kHz, from 0.7 kV to 1.8 kV in 0.1 kV increments. Each color was modified so that a monochrome image could be output.

[0160] The evaluation items are shown below. (1) Image density After initial durability and durability image output evaluation (A4 landscape, 40% print ratio, 50,000 sheets) under a high temperature and humidity environment (30°C, 80% RH), a solid image (FFH) was output. Density was measured using a densitometer X-Rite 404A (manufactured by X-Rite), and the average value of six points was taken as the image density. The difference in image density between the initial durability and the durability image output was judged according to the following criteria. When the evaluation was A to C, it was determined that the effects of the present invention were obtained. A: The difference in concentration is less than 0.10 B: The difference in density is 0.10 or more and less than 0.15 C: The difference in density is 0.15 or more and less than 0.20 D: The difference in density is 0.20 or more and less than 0.25 E: The density difference is 0.25 or more

[0161] (2) Coverage After initial durability and durability image output evaluation (A4 landscape, 40% print ratio, 50,000 sheets) were performed in a high temperature and high humidity environment (30°C, 80% RH), an A4 full-page solid white image was output. Fog was measured by measuring the whiteness of the white background with a reflectometer (Tokyo Denshoku Co., Ltd.), and the fog density (%) was calculated from the difference in whiteness before and after transfer and evaluated according to the following criteria. When the evaluation was A to C, it was determined that the effects of the present invention were achieved. A: Less than 1.0% B: 1.0% or more and less than 1.5% C: 1.5% or more and less than 2.0% D: 2.0% or more and less than 2.5% E: 2.5% or more

[0162] (3) Halftone development After initial durability and durability image output evaluations (A4 landscape, 40% print ratio, 50,000 sheets) were conducted under a high-temperature, high-humidity environment (30°C, 80% RH), a halftone image (30H) was printed on one A4 sheet, and the area of ​​1,000 dots was measured using a digital microscope VHX-500 (lens wide-range zoom lens VH-Z100, Keyence Corporation). The number average dot area (S) and standard deviation of dot area (σ) were calculated, and the dot reproducibility index was calculated using the following formula. The roughness of the halftone image was then evaluated using the dot reproducibility index (I). Dot reproducibility index (I) = σ / S × 100 The roughness was evaluated according to the following criteria: When the evaluation was A to C, it was determined that the effects of the present invention were obtained. A:I is less than 4.0 B: I is 4.0 or more and less than 5.0 C:I is 5.0 or more and less than 6.0 D:I is 7.0 or more and less than 8.0 E:I is 8.0 or higher

[0163] (4) Toner scattering After initial durability and durability image output evaluation (A4 landscape, 40% print ratio, 50,000 sheets) were performed in a high temperature and high humidity environment (30°C, 80% RH), the developing unit was removed from the main body, and the toner scattering status inside and outside the developing unit and the main body was visually inspected and evaluated according to the following criteria. If the evaluation was A to C, it was determined that the effects of the present invention were achieved. A: No toner scattering B: Very slight toner scattering C: Slight toner scattering D: Toner scattering E: Significant toner scattering Table 5 shows the results obtained in the above evaluations (1) to (4).

[0164] (Examples 2 to 33 and Comparative Examples 1 to 7) Two-component developers 2 to 40 and replenishment developers 2 to 40 were prepared in the same manner as in Example 1, except that magnetic carrier 1 in Example 1 was changed to magnetic carriers 2 to 40 as shown in Table 4, and similar evaluations (1) to (4) were performed. The results obtained are shown in Table 5.

[0165] [Table 4]

[0166] [Table 5] [Explanation of symbols]

[0167] 1 Electrostatic latent image carrier 2 Charger 3 Exposure device 4 Developer 5 Developer container 6 Developer carrier 7. Magnet 8 Regulatory Members 11 Transfer charger 12 Recording medium (transfer material) 13 Fixing unit 15. Cleaner 16 Pre-exposure device

Claims

1. A magnetic carrier having a magnetic core and a coating resin that coats the surface of the magnetic core, The coating resin contains resin A and resin B, the content of the resin A is 1% by mass or more and 50% by mass or less, and the content of the resin B is 50% by mass or more and 99% by mass or less, based on the total mass of the coating resin; The resin A has a unit Y1 represented by the following formula (1) and a unit Y2 represented by the following formula (2), The resin B has a content of units Y2 represented by the following formula (2) of 0.1 mass % or less, When the mass of the resin A, the mass of the unit Y1 in the resin A, and the mass of the unit Y2 in the resin A are X, a, and b, respectively, X, a, and b are represented by the following formulas (a) and (b): 0.90≦(a+b) / X≦1.00 (a) 1.00≦a / b≦30.0 (b) Fulfilling When the SP value of the unit Y1 and the SP value of the resin B are SPa and SPb, respectively, the Spa and the SPb are expressed by the following formula (c): 0≦|SPa-SPb|≦2.0 (c) A magnetic carrier characterized by satisfying the above. (In formula (1), R １ is H or CH ３ represents R ２ represents a hydrocarbon group having 1 to 8 carbon atoms which may have a substituent, and the substituent is a hydroxy group or a carboxy group. (In formula (2), R ３ is H or CH ３ represents R ４ is H or CH ３ represents R ５ represents a single bond or a hydrocarbon group having 1 to 10 carbon atoms, R ６ represents a hydrocarbon group having 1 to 10 carbon atoms, R ７ is H, CH ３ or Si(CH ３ ) ３ represents n represents an integer of 2 or more and 150 or less. 【Chemistry 1】 【Chemistry 2】

2. The resin B contains 75 mass % or more of the unit Y1 represented by the formula (1), The magnetic carrier according to claim 1 .

3. 3. The magnetic carrier according to claim 1, wherein n in formula (2) is 5 or more and 60 or less.

4. 4. The magnetic carrier according to claim 1, wherein the surface of the magnetic carrier has a Si content of 1.0 atomic % or more and 15.0 atomic % or less as determined by ESCA analysis.

5. 5. The magnetic carrier according to claim 1, wherein the following formula is satisfied when the sum of the numbers of units Y1 and units Y2 represented by formulas (1) and (2) is m: 50≦m≦250

6. 6. The magnetic carrier according to claim 1, wherein the coating resin contains 1% by mass or more and 20% by mass or less of resin A and 80% by mass or more and 99% by mass or less of resin B.

7. 7. The magnetic carrier according to claim 1, wherein the resin B has a unit Y3 represented by the following formula (3), and the content of the unit Y3 is 1% by mass or more and 75% by mass or less based on the resin B: 【Transformation 3】 (In formula (3), R ８ represents a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclopentyl group, a cyclobutyl group, or a cyclopropyl group.

8. A two-component developer comprising the magnetic carrier according to any one of claims 1 to 7 and a toner.

9. A replenishing developer containing the magnetic carrier according to any one of claims 1 to 7.

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