JP5546260B2 - Method for producing magnetic toner particles - Google Patents

Description

  The present invention relates to a magnetic toner used in a recording method using an electrophotographic method, an electrostatic recording method, and a toner jet recording method.

In magnetic toner particles as a developer used in the magnetic one-component development system, a considerable amount of magnetic iron oxide is mixed and dispersed. This may cause problems such as a decrease in image density and a decrease in toner durability. That is, the dispersibility of the magnetic iron oxide is important for improving the image density and the toner durability performance of the magnetic toner.
Furthermore, there is an increasing demand for image forming apparatuses to develop images with higher image quality in recent years. Therefore, magnetic toner characteristics required for that purpose include a sharp particle size distribution and uniform circularity. Therefore, as a production method for obtaining a magnetic toner having such characteristics, the materials are dispersed in a dispersion liquid, and after mixing these to form aggregated particles corresponding to the toner particle size, melting is performed by heating, Various studies have been conducted on a production method for obtaining magnetic toner particles, a so-called emulsion aggregation method.
As a recent study on the emulsion aggregation method, for example, a method for obtaining a magnetic toner using a surface-controlled magnetic iron oxide in consideration of the dispersibility of the magnetic iron oxide in the dispersion has been studied. (Patent Document 1). Further, a method for obtaining a magnetic toner in which magnetic iron oxide is not exposed on the surface by controlling the zeta potential of the dispersion has been studied (Patent Document 2). In addition, a method for improving the inclusion of magnetic iron oxide in a magnetic toner by using magnetic iron oxide whose surface is treated with a metal compound is disclosed (Patent Document 3). Further, a study has been disclosed in which dispersibility is improved while coating the surface of magnetic iron oxide in the dispersion with crystalline polyester to prevent oxidation of magnetic iron oxide in the dispersion (Patent Document 4). ).

JP 2004-287153 A JP-A-2005-99179 JP 2006-84600 A JP 2007-171692 A

However, the above-mentioned publication does not mention the problem that the release agent is exposed on the surface of the magnetic toner particles due to the influence of the dispersibility of the magnetic iron oxide. When the release agent is exposed on the surface of the magnetic toner particles, there is a possibility that the image density and durability are remarkably lowered after use for a long period of time in a high temperature and high humidity environment.
Therefore, the present invention has been made in view of the above-described circumstances in the prior art for the purpose of improving the drawbacks. That is, the object of the present invention is to improve the dispersibility of the magnetic iron oxide contained in the magnetic toner particles while considering the influence on the release agent, so that the image can be used even after long-term storage in a high temperature and high humidity environment. It is an object of the present invention to provide a magnetic toner capable of maintaining density and toner durability performance.

Means for achieving the above object are as follows.
A step of preparing a binder resin fine particle dispersion in which binder resin fine particles are dispersed in an aqueous medium; a step of preparing a magnetic iron oxide fine particle dispersion in which magnetic iron oxide fine particles are dispersed in an aqueous medium; A step of preparing a release agent fine particle dispersion dispersed in a medium, the binder resin fine particle dispersion, the magnetic iron oxide fine particle dispersion, and the release agent fine particle dispersion are mixed so that the aggregated particles are in an aqueous medium. A method for producing magnetic toner particles, comprising: an aggregating step of preparing an aggregated particle dispersion dispersed in the resin; and a melting step of melting / fusion of the aggregated particles to obtain magnetic toner particles. Chakujushi, magnetic iron oxide particles, and the releasing agent contains at least the binder resin contains as a main component at least polyester resin, wherein the magnetic iron oxide particles, the magnetic iron oxide particles 20 parts by mass After they were dispersed in 80 parts by weight of isopropyl alcohol, allowed to stand, in isopropyl alcohol precipitation test of measuring the time course for the precipitation volume of the magnetic iron oxide particles, precipitation of standing to 10 minutes after the magnetic iron oxide particles In an ethyl acetate precipitation test in which the volume is _VIPA , 20 parts by mass of the magnetic iron oxide particles are dispersed in 80 parts by mass of ethyl acetate, and then allowed to stand, and the change over time of the precipitation volume of the magnetic iron oxide particles is measured. the precipitate volume of the magnetic iron oxide particles to 10 minutes after location and V _EtA, the total volume up to the liquid level of ethyl acetate is taken as v _EtA, the ratio V _IPA / V of the V _IPA and V _{EtA EtA} is, is 1.2 to 3.0, the ratio V _EtA / v _EtA between the V _EtA and v _EtA is 0.2 to 0.7, the magnetic toner particles, wherein Manufacturing method .

  According to the preferred embodiment of the present invention, the dispersibility of the magnetic iron oxide contained in the magnetic toner is improved while considering the influence on the release agent, and the image can be used even after long-term storage in a high temperature and high humidity environment. A magnetic toner capable of maintaining density and toner durability can be provided.

The magnetic toner of the present invention contains magnetic toner particles containing at least a binder resin, magnetic iron oxide, and a release agent, and hydrophobic inorganic fine particles.
In the present invention, the magnetic toner and the magnetic toner particles are used separately. A form in which hydrophobic inorganic fine particles are externally added to magnetic toner particles in order to adjust powder flowability and chargeability is called magnetic toner. Here, magnetic iron oxide has a function of imparting magnetization and a function of coloring as a magnetic toner used in the magnetic one-component development system.
The binder resin used in the magnetic toner of the present invention contains a polyester resin as a main component because good fixing performance can be obtained. Here, the “main component” means that the proportion of the polyester resin in the binder resin is 50% by mass or more. The proportion of the polyester resin in the binder resin is preferably 70% by mass or more, more preferably 90% by mass or more, and particularly preferably 100% by mass.
The polyester resin may include an amorphous polyester resin and a crystalline polyester resin.

The magnetic toner particles of the present invention are magnetic toner particles obtained by an emulsion aggregation method. The emulsion aggregation method is a binder resin fine particle dispersion in which binder resin fine particles are dispersed at least 1 μm or less, a magnetic iron oxide fine particle dispersion in which magnetic iron oxide fine particles are dispersed, and a release agent in which release agent fine particles are dispersed. A first step (hereinafter sometimes referred to as an aggregating step) in which the fine particle dispersion is mixed to form aggregated particles corresponding to the toner particle size, and the aggregated particles are equal to or higher than the glass transition point of the binder resin fine particles. This is a manufacturing method for obtaining a magnetic toner through a second step (hereinafter sometimes referred to as a melting step) in which the aggregated particles are melted / fused by heating to a temperature of 2 to obtain magnetic toner particles.
Furthermore, in the present invention, it is preferable to include a step (hereinafter referred to as an adhesion step) in which fine particles capable of forming a shell layer containing resin fine particles are adhered to the surface of the aggregated particles after obtaining the aggregated particles.
When magnetic toner particles are obtained by the emulsion aggregation method, the dispersion state of the binder resin fine particles, magnetic iron oxide fine particles, and release agent fine particles in the aggregated particles is particularly great when forming the aggregated particles in the first step. is important. In the production of magnetic toner particles by the emulsion aggregation method of the present invention, since an aqueous medium is used, the aggregate in which the surface of the magnetic iron oxide fine particles is covered with the binder resin fine particles is relatively easily mixed with water, It is easy to exist. On the other hand, the release agent fine particles are less likely to blend with water and are likely to be present inside the magnetic toner particles, and the release agent fine particles are less likely to be present on the surface of the magnetic toner particles. As a result, the magnetic toner particle surface is covered with binder resin fine particles,
It is easy to adopt a configuration in which magnetic iron oxide fine particles and release agent fine particles are encapsulated in magnetic toner particles.
However, when the magnetic iron oxide fine particles and the release agent fine particles are exposed on the surface of the magnetic toner particles, there is a possibility of causing a bad image. For example, when a large number of magnetic iron oxide particles are present on the surface of the aggregated particles, the magnetic iron oxide particles on the surface of the magnetic toner particles are detached from the surface of the magnetic toner particles when used after long-term storage in a high-temperature and high-humidity environment. Charging becomes unstable and the image density tends to decrease. In addition, if there are many release agent fine particles on the surface of the aggregated particles, there are also many release agents on the surface of the magnetic toner particles, so that external additives are embedded in the surface of the magnetic toner particles during long-term storage in a high temperature and high humidity environment. In some cases, the image density decreases due to long-term use. In addition, when a large number of magnetic iron oxide fine particles and release agent fine particles are present on the surface of the aggregated particles, the adhered particles cannot be uniformly adhered to the surface of the aggregated particles in the adhesion step, resulting in uneven adhesion and a decrease in image density. Or toner durability may be reduced. For the above reasons, when the aggregated particles are formed in the first step, it is preferable that the exposure of the magnetic iron oxide particles and the release agent fine particles to the surface of the aggregated particles is small. More preferably, the surface of the aggregated particles is uniformly covered with binder resin fine particles.
In order to obtain such aggregated particles, when the aggregated particles are formed in the aggregation step, the binder resin fine particles may be aggregated so as to surround the magnetic iron oxide fine particles. When the binder resin fine particles surround the magnetic iron oxide fine particles, the magnetic iron oxide fine particles are not exposed on the surface of the aggregate, and the above-described charging failure of the magnetic toner does not occur. On the other hand, in the present invention, it is also important that the magnetic iron oxide fine particles and the release agent fine particles are aggregated so as not to contact each other. When the aggregated particles are produced in a state where the magnetic iron oxide fine particles and the release agent fine particles are in contact with each other, the magnetic iron oxide fine particles and the release agent are brought into contact with each other in the magnetic toner particles. Here, since the interface between the magnetic iron oxide fine particles and the release agent has a lower adhesive strength than the interface between the magnetic iron oxide fine particles and the binder resin fine particles, the magnetic toner particles having a large interface between the magnetic iron oxide fine particles and the release agent. May be prone to cracking. If the magnetic toner particles are broken, the surface of the magnetic toner particles to which no external additive is attached is exposed on the cross section of the magnetic toner particles, which may cause a decrease in fluidity and chargeability. In addition, the magnetic iron oxide fine particles present at the interface between the magnetic iron oxide fine particles and the release agent are released from the magnetic toner, and the possibility that the image density is lowered increases due to the increase of the magnetic toner having a small particle diameter. . In particular, the above problem is likely to occur when the magnetic toner is likely to deteriorate due to long-term use in a high temperature and high humidity environment. That is, the magnetic iron oxide particles used in the present invention are preferably in contact with the binder resin fine particles and not in contact with the release agent fine particles in the aggregation step. A factor that determines the contact state between the magnetic iron oxide particles, the binder resin fine particles, and the release agent fine particles includes the affinity between the magnetic iron oxide particles, the binder resin fine particles, and the release agent fine particles.

From the above, the present inventors have found that it is important that the magnetic iron oxide has an affinity within a specific range for the binder resin and the release agent when forming the aggregated particles in the aggregation process. It was.
In general, the affinity between two substances can be determined by the polarity of the substances. The smaller the polarity difference is, the higher the affinity is. On the contrary, the larger the polarity difference is, the lower the affinity is.
Therefore, as an index indicating the affinity between magnetic iron oxide and binder resin, after sufficiently dispersing magnetic iron oxide in a solvent close to the polarity of the binder resin, it was allowed to stand, and a value obtained by evaluating the rate of decrease in the precipitation volume was obtained. It is suitable to use. Since the magnetic toner particles of the present invention have a binder resin containing at least a polyester resin as a main component, in order to evaluate the affinity between the magnetic iron oxide and the binder resin, isopropyl alcohol (with a polarity close to that of the polyester resin) Hereinafter, isopropyl alcohol may be referred to as “IPA”). Normally, in the category of polyester resins used for toner applications, even if the monomer composition constituting the polyester resin is changed, it is considered that there is not so much difference in polarity. It is considered that isopropyl alcohol can be used for the evaluation of the affinity.
Here, since the true density of magnetic iron oxide (density excluding voids) is larger than the true density of IPA, magnetic iron oxide forms a precipitate in IPA. The small decrease rate of the precipitation volume means that magnetic iron oxide has a high affinity with IPA (ie, binder resin). On the other hand, a large decrease rate of the precipitation volume means that the magnetic iron oxide has a low affinity with the binder resin.

For the same reason, as an index indicating the affinity between magnetic iron oxide and the release agent, after sufficiently dispersing the magnetic iron oxide in a solvent close to the polarity of the release agent, the magnetic iron oxide is allowed to stand and the rate of decrease in the precipitation volume is determined. It is suitable to use the evaluated value. In order to evaluate the affinity between the magnetic iron oxide and the release agent, ethyl acetate having a polarity similar to that of the release agent was selected. Here, in view of the polarities of the polyester resin and the release agent, it is considered that the polarity of the release agent used for toner and the ethyl acetate are closer.
Since the true density of magnetic iron oxide (the density excluding voids) is larger than the true density of ethyl acetate, magnetic iron oxide forms a precipitate in ethyl acetate. The low rate of precipitation volume reduction means that magnetic iron oxide has a high affinity for ethyl acetate (ie, release agent). On the other hand, a large decrease rate of the precipitation volume means that the magnetic iron oxide has a low affinity with the release agent.

That is, the magnetic iron oxide used in the magnetic toner of the present invention is isopropyl alcohol in which 20 parts by mass of magnetic iron oxide is dispersed in 80 parts by mass of isopropyl alcohol, and then allowed to stand and the change with time of the precipitation volume of the magnetic iron oxide is measured. in precipitation test, standing the precipitate volume of the magnetic iron oxide after 10 minutes and V _IPA, after 20 parts by mass magnetic iron oxide was dispersed in 80 parts by mass of ethyl acetate, allowed to stand, precipitating magnetic iron oxide In the ethyl acetate precipitation test in which the change over time was measured for the volume, when the precipitation volume of magnetic iron oxide after standing for 10 minutes was V _EtA and the total volume up to the liquid level of ethyl acetate was v _EtA , the ratio V _IPA / V _EtA of the V _IPA and V _EtA is, 1.2 more than 3
. The ratio V _EtA / v _EtA between V _EtA and v _EtA is 0.2 or more and 0.7 or less.
The precipitation volume after 10 minutes after standing is the precipitation volume after 10 minutes have passed after sufficiently dispersing magnetic iron oxide in IPA or ethyl acetate. Further, the reason for adopting the precipitation volume after 10 minutes of standing is that the standing 10 is used to evaluate the behavior of the magnetic iron oxide fine particles in the first step of forming the aggregated particles in the fine particle mixed dispersion. This is because the minutes are considered appropriate. The reason for this is not clear, but when the correlation with the magnetic iron oxide dispersion state in the magnetic toner particles was confirmed, the best correlation was shown after 10 minutes of standing.
When the ratio V _IPA / V _{EtA of} V _IPA and V _EtA is less than 1.2, it means that the affinity ratio between magnetic iron oxide and IPA and the affinity ratio between magnetic iron oxide and ethyl acetate are small. Yes. That is, magnetic iron oxide may be considered to have a close affinity for the binder resin and the release agent. That is, it is considered that the magnetic iron oxide fine particles contained in the aggregated particles in the first step are easily in contact with both the binder resin fine particles and the release agent fine particles. For this reason, there are many interfaces between the magnetic iron oxide fine particles and the release agent in the magnetic toner particles, and as described above, there is a possibility that the image density is lowered when used after long-term storage in a high temperature and high humidity environment. There is.
In addition, when there are magnetic iron oxide particles in contact with both the binder resin fine particles and the release agent fine particles, the binder resin fine particles and the release agent fine particles in contact with the magnetic iron oxide particles are likely to be present on the surface of the aggregate. . As described above, when a large number of release agent fine particles are present on the surface of the agglomerated particles, a large amount of release agent is also present on the surface of the magnetic toner particles. It becomes easy to be embedded in the surface, and a decrease in image density may occur due to long-term use. Further, since the magnetic iron oxide fine particles, the binder resin fine particles, and the release agent fine particles are present on the surface of the aggregated particles and become a non-uniform surface, in the step of attaching the fine particles to the aggregated particles in the adhesion step, There is a possibility that unevenness occurs in the adhesion of the fine particles, resulting in a problem that the surface of the obtained magnetic toner is not uniformly covered with the fine particles. Even if the adhesion process is not performed and the process proceeds to the melting process, there is a possibility that the surface of the obtained magnetic toner is not uniformly covered with the resin.
As described above, when there are a large number of magnetic iron oxide fine particles and release agent fine particles on the surface of the magnetic toner, the magnetic toner after long-term storage in a high-temperature and high-humidity environment becomes unstable in charge of the toner, or external additives are added. By being embedded in the surface of the magnetic toner, a decrease in image density and durability may be a problem.
On the other hand, when the ratio V _IPA / V _{EtA of} V _IPA and V _EtA exceeds 3.0, it indicates that the affinity ratio between magnetic iron oxide and IPA and the affinity ratio between magnetic iron oxide and ethyl acetate are large. Yes. That is, it may be considered that magnetic iron oxide has a higher affinity with the binder resin than the release agent. That is, the magnetic iron oxide fine particles contained in the aggregated particles in the first step are considered to be in contact with the binder resin fine particles and not in contact with the release agent fine particles. In this case, since the magnetic iron oxide fine particles do not accompany the release agent fine particles, it becomes difficult for the release agent fine particles to be present on the surface of the aggregated particles. On the other hand, the magnetic iron oxide fine particles tend to selectively aggregate with the binder resin fine particles, and the possibility that the release agent fine particles exist alone increases. As a result, the release agent fine particles are not contained in the set amount in the agglomerated particles, causing a decrease in low-temperature fixing performance. In addition, the release agent fine particles may not be taken into the aggregated particles, and the release agent fine particles that existed alone in the medium may be reattached to the surface of the magnetic toner particles, thereby reducing the durability of the magnetic toner.
The V _IPA / V _EtA is preferably 1.5 or more and 2.8 or less. The above _VIPA
A measure for adjusting / V _EtA to the above range will be described later.

As a means for improving the dispersibility of the magnetic iron oxide fine particles in the magnetic toner, the affinity ratio between the magnetic iron oxide and ethyl acetate and IPA is within a specific range, and the affinity between the magnetic iron oxide and ethyl acetate. It is necessary to set the property within a specific range as a means for bringing the magnetic iron oxide particles and the release agent fine particles into non-contact.
Accordingly, the magnetic iron oxide used in the magnetic toner of the present invention is ethyl acetate in which 20 parts by mass of magnetic iron oxide is dispersed in 80 parts by mass of ethyl acetate and then allowed to stand to measure the change with time of the precipitation volume of the magnetic iron oxide. in precipitation test, standing the precipitate volume of the magnetic iron oxide after 10 minutes and V _EtA by the total volume up to the liquid level of ethyl acetate is taken as v _EtA, the ratio between the V _EtA and v _EtA V _EtA / v _EtA is 0.2 or more and 0.7 or less.
The v _EtA the ratio V _EtA / v _EtA the V _EtA does not become less than 0.2. This is because even if the magnetic iron oxide is completely precipitated in ethyl acetate, the precipitation does not become 0 and V _EtA / v _EtA becomes 0.2 depending on the volume of the magnetic iron oxide.
Further, when V _EtA / v _EtA exceeds 0.7, it indicates that the affinity between magnetic iron oxide and ethyl acetate is too high. In such a case, as described above, since the release agent fine particles brought along with the magnetic iron oxide fine particles exist on the surface of the aggregated particles, the charging of the magnetic toner becomes unstable after long-term storage in a high temperature and high humidity environment. Therefore, a decrease in image density becomes a problem.
The V _EtA / v _EtA is preferably 0.3 or more and 0.6 or less. The above V _EtA
A method for adjusting / v _EtA to the above range will be described later.

In the present invention, when the polyester resin contains a predetermined amount of a crystalline polyester resin, it is preferable from the viewpoint of fixing performance. The content of the crystalline polyester resin is preferably 1% by mass or more and 50% by mass or less with respect to the entire polyester resin. Furthermore, it is more preferable that it is 1 mass% or more and 40 mass% or less.
Since the crystalline polyester resin has sharp melt characteristics as compared with the non-crystalline polyester resin, it can provide good low-temperature fixing performance while ensuring heat-resistant storage stability of the magnetic toner.
Since the viscosity of the crystalline polyester resin is drastically lowered at a temperature exceeding the melting point, when the magnetic polyester is obtained by the emulsion aggregation method, the crystalline particles are fused and heated when the crystalline polyester resin is used as the binder resin. At this time, the crystalline polyester resin is melted and the viscosity is rapidly lowered. When the viscosity of the crystalline polyester resin existing around the magnetic iron oxide fine particles in the aggregated particles in the melting process is lowered, the affinity with the binder resin and the release agent as in the prior art is not controlled. With such magnetic iron oxide, there was a problem that the magnetic iron oxide fine particles easily move, and stable dispersion performance cannot be secured. As a result, the magnetic iron oxide fine particles that have become easy to move exist on the surface of the magnetic toner particles and act as a leak site that escapes the charging of the magnetic toner, so that the charging of the magnetic toner becomes unstable and the image density decreases. There was a possibility of causing image defects such as.
However, when magnetic iron oxide satisfying the provisions of the present invention is used, even if a crystalline polyester resin is contained, even if the viscosity of the crystalline polyester resin around the magnetic iron oxide fine particles suddenly decreases, the magnetic Since the affinity between the iron oxide fine particles and the binder resin fine particles is high, the magnetic iron oxide fine particles do not move, and the magnetic iron oxide fine particles do not easily exist on the surface of the magnetic toner particles. Therefore, it is possible to provide a magnetic toner that can obtain a good image and achieves a good low-temperature fixing performance.

A preferred embodiment of the emulsion aggregation method used for producing magnetic toner particles in the present invention will be described below.
(Binder resin)
The binder resin used in the magnetic toner of the present invention contains a polyester resin as a main component. Moreover, a polyester resin can be contained with an amorphous polyester resin and a crystalline polyester resin. An amorphous polyester resin is a resin that does not have an endothermic peak associated with crystal melting in thermal analysis using differential scanning calorimetry (DSC), is a solid at room temperature, and is heated at a temperature above the glass transition temperature. Refers to plasticizing.
As such an amorphous polyester resin, a suitable one is usually selected and combined from a dicarboxylic acid component and a diol component, for example, using a conventionally known method such as a transesterification method or a polycondensation method. Can be synthesized.
Examples of the dicarboxylic acid component include terephthalic acid, isophthalic acid, cyclohexanedicarboxylic acid, naphthalene-2carboxylic acid such as naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, and biphenyldicarboxylic acid. In addition, dibasic acids such as succinic acid, glutaric acid, adipic acid, speric acid, azelaic acid, sebacic acid, phthalic acid, malonic acid, and mesaconic acid, and anhydrides and lower alkyl esters thereof; maleic acid, fumaric acid Examples thereof include aliphatic unsaturated dicarboxylic acids such as acid, itaconic acid and citraconic acid. Further, trivalent or higher carboxylic acids such as 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid and the like, and anhydrides and lower alkyl esters thereof. Can be used in combination. In addition, it is also possible to use monovalent acids, such as an acetic acid and a benzoic acid, as needed for the purpose of adjustment of an acid value or a hydroxyl value.
On the other hand, examples of the diol component include ethylene glycol, propylene glycol, neopentyl glycol, cyclohexanedimethanol, ethylene oxide adduct of bisphenol A, propylene oxide adduct of bisphenol A, trimethylene oxide adduct of bisphenol A, and the like. Bisphenol A, hydrogenated bisphenol A, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, diethylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentane Examples include diol, 1,6-hexanediol, neopentyl glycol, and the like. Furthermore, if it is trace amount, trivalent or more alcohols, such as glycerol, a trimethylol ethane, a trimethylol propane, a pentaerythritol, can be used together. These may be used individually by 1 type and may use 2 or more types together. Monovalent alcohols such as cyclohexanol and benzyl alcohol can also be used.

As described above, the polyester resin can contain a crystalline polyester resin.
The crystalline polyester resin is a resin in which an endothermic peak accompanying crystal melting exists in thermal analysis measurement using differential scanning calorimetry (DSC), is a solid at room temperature, and is thermoplastic at a temperature equal to or higher than the glass transition temperature. It refers to things that change.
The melting point of the crystalline polyester is preferably in the range of 60 to 120 ° C, and more preferably in the range of 60 to 100 ° C. Within this range, heat-resistant storage stability and low-temperature fixing performance are further improved.
The crystalline polyester is preferably synthesized from a dicarboxylic acid component and a diol component.
Examples of the aliphatic dicarboxylic acid that can be used in the crystalline polyester of the present invention include the following. Succinic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, and the like. Or its lower alkyl ester and acid anhydride.
Of these, sebacic acid, 1,10-decanedicarboxylic acid or its lower alkyl ester and acid anhydride are preferred.
Examples of the aromatic dicarboxylic acid that can be used in the crystalline polyester of the present invention include the following. Terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4′-biphenyldicarboxylic acid and the like.
Among these, terephthalic acid is preferable in terms of availability, easy formation of a low melting point polymer, and the like.
A dicarboxylic acid having a double bond can also be used for the crystalline polyester of the present invention. A dicarboxylic acid having a double bond can be suitably used in order to prevent hot offset at the time of fixing, because the entire resin can be crosslinked using the double bond. Examples of such dicarboxylic acids include, but are not limited to, fumaric acid, maleic acid, 3-hexenedioic acid, and 3-octenedioic acid. Moreover, these lower alkyl esters, acid anhydrides, etc. are also mentioned. Among these, fumaric acid, maleic acid and the like are preferable in terms of cost.
Catalysts that can be used during the production of the crystalline polyester resin and the amorphous polyester resin include alkali metal compounds such as sodium and lithium, alkaline earth metal compounds such as magnesium and calcium, zinc, manganese, antimony, titanium, tin, Examples thereof include metal compounds such as zirconium and germanium, phosphorous acid compounds, phosphoric acid compounds, and amine compounds. Specifically, sodium acetate, sodium carbonate, lithium acetate, lithium carbonate, calcium acetate, calcium stearate, magnesium acetate, zinc acetate, zinc stearate, zinc naphthenate, zinc chloride, manganese acetate, manganese naphthenate, titanium tetraethoxy , Titanium tetrapropoxide, titanium tetraisopropoxide, titanium tetrabutoxide, antimony trioxide, triphenylantimony, tributylantimony, tin formate, tin oxalate, tetraphenyltin, dibutyltin dichloride, dibutyltin oxide, diphenyltin oxide, zirconium tetra Butoxide, Zirconium naphthenate, Zirconyl carbonate, Zirconyl acetate, Zirconyl stearate, Zirconyl octylate, Germanium oxide, Trif Alkenyl phosphite, tris (2,4-di -t- butyl-phenyl) phosphite, ethyltriphenylphosphonium bromide, triethylamine, compounds such as triphenyl amine.
On the other hand, the binder resin used in the present invention can contain other resins to the extent that the effects of the present invention are not affected, in addition to the polyester resin as a main component. Examples of the resin include a thermoplastic binder resin. Specifically, homopolymers or copolymers of styrenes such as styrene, parachlorostyrene, α-methylstyrene (styrene resin); methyl acrylate, ethyl acrylate, n-propyl acrylate, n-acrylate -Homopolymers or copolymers of esters having vinyl groups such as butyl, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, etc. Polymer (vinyl resin); homopolymer or copolymer of vinyl nitriles such as acrylonitrile and methacrylonitrile (vinyl resin); homopolymer or copolymer of vinyl ethers such as vinyl methyl ether and vinyl isobutyl ether Coalescence (vinyl resin); vinyl methyl ketone, Homopolymers or copolymers of vinyl ketones such as nil ethyl ketone and vinyl isopropenyl ketone (vinyl resins); Homopolymers or copolymers of olefins such as ethylene, propylene, butadiene and isoprene (olefin resins) Non-vinyl condensation resins such as epoxy resins, polyester resins other than those mentioned above, polyurethane resins, polyamide resins, cellulose resins, polyether resins, and graft polymers of these non-vinyl condensation resins and vinyl monomers Can be mentioned.

(Preparation of binder resin fine particle dispersion)
When an amorphous polyester resin or a crystalline polyester resin is used as the binder resin, it is preferable to emulsify the amorphous polyester resin or the crystalline polyester resin to form emulsified particles. For example, the non-crystalline polyester resin emulsified particles are formed by applying a shearing force to a solution in which an aqueous medium and at least a polyester resin are mixed. At this time, by heating to a temperature equal to or higher than the glass transition temperature of the amorphous polyester resin, the viscosity of the polymer liquid is lowered to form emulsified particles, whereby a binder resin fine particle dispersion can be obtained.
In the present invention, it is preferable to use a phase inversion emulsification method in order to emulsify the resin. In the phase inversion emulsification method, at least a polyester resin is dissolved in an organic solvent, a neutralizing agent and a dispersion stabilizer are added as necessary, and an aqueous medium is dropped under stirring to obtain emulsified particles. In this method, the solvent in the resin dispersion is removed to obtain an emulsion. At this time, the order of adding the neutralizing agent and the dispersion stabilizer may be changed.
Examples of the emulsifier used when forming the emulsified particles include a homogenizer, a homomixer, and an extruder. The average particle diameter (volume average particle diameter) of the emulsified particles of the polyester resin is preferably in the range of 0.1 to 0.3 μm. If it is less than 0.1 μm, most of the emulsified particles are dissolved in water, making it difficult to produce the particles. If it exceeds 0.3 μm, particles having a desired particle size of 3.0 to 7.5 μm are obtained. It may be difficult to obtain. The volume average particle diameter of the resin particles can be measured with, for example, a Doppler scattering type particle size distribution measuring apparatus (manufactured by Nikkiso Co., Ltd., Microtrac UPA9340).
Examples of the organic solvent for dissolving the resin include formic acid esters, acetic acid esters, butyric acid esters, ketones, ethers, benzenes, and halogenated carbons. Specifically, esters such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl such as formic acid, acetic acid and butyric acid; acetone, MEK (methyl ethyl ketone), MIPK (methyl isopropyl) Ketones), methyl ketones such as MBK (methyl butyl ketone) and MIBK (methyl isobutyl ketone); ethers such as diethyl ether and diisopropyl ether; aromatic hydrocarbons such as toluene, xylene and benzene: heterocyclic compounds such as tetrahydrofuran Carbon halides such as carbon tetrachloride, trichloroethylene, 1,2-dichloroethane, chloroform, dichloroethylidene monochlorobenzene, and the like can be used alone or in combination of two or more. Acetic acid esters, methyl ketones and ethers of low-boiling solvents (50 to 150 ° C.) are usually preferably used from the viewpoint of easy availability, ease of recovery during solvent removal, and environmental considerations, particularly acetone and methyl ethyl ketone. Those having partial solubility in water such as acetic acid, ethyl acetate, and butyl acetate are preferred. If the organic solvent remains in the resin particles, the surface of the heating member may be denatured at the time of fixing. Therefore, it is preferable to use a solvent having a relatively high volatility.
As the aqueous medium, ion-exchanged water is basically used, but a water-soluble organic solvent may be included so as not to destroy the oil droplets. Examples of water-soluble organic solvents include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, t-butanol, 1-pentanol and other short carbon chain alcohols; ethylene glycol monomethyl ether, ethylene glycol Ethylene glycol monoalkyl ethers such as monoethyl ether; ethers, diols, THF, acetone and the like. The mixing ratio of these water-soluble organic solvents to ion-exchanged water is selected in the range of 1% to 50%, more preferably 1% to 30%, and used as an aqueous component. In addition, the water-soluble organic solvent may be added to the resin solution and used in addition to the ion-exchanged water to be added.
Moreover, you may add a dispersing agent to a resin solution and an aqueous component as needed so that the said emulsion may maintain a dispersed state stably. Examples of the dispersant include those that form a hydrophilic colloid in an aqueous component, particularly cellulose derivatives such as hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose; polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, polyacrylate, Synthetic polymers such as polymethacrylates; dispersion stabilizers such as gelatin; gum arabic; agar; Solid fine powders such as silica, titanium oxide, alumina, tricalcium phosphate, calcium carbonate, calcium sulfate, and barium carbonate can also be used. These dispersants are usually added so that the concentration in the aqueous component is 0 to 20% by mass, desirably 0 to 10% by mass.
A surfactant is also used as the dispersant. Examples of the surfactant include, in addition to natural surfactant components such as saponin, cationic surfactants such as alkylamine hydrochloride / acetates, quaternary ammonium salts, glycerols, anionic surfactants, Nonionic surfactants are preferably used. Further, a neutralizing agent may be added to adjust the pH of the emulsion. As the neutralizing agent, general acids such as nitric acid, hydrochloric acid, sodium hydroxide and ammonia, and alkalis can be used.
As a method for removing the organic solvent from the emulsion, a method in which the organic solvent is volatilized at room temperature (20 to 25 ° C.) or under heating, and a method in which this is combined with reduced pressure are preferably used.
On the other hand, as a dispersion method in a solvent, for example, a general dispersion method such as a rotary shear type homogenizer, a ball mill having a medium, a sand mill, or a dyno mill can be used, and the method is not limited at all.

(Magnetic iron oxide)
The magnetic iron oxide used in the present invention preferably contains at least a Ti component, an Al component, an Si component, and an Fe component. By containing these elements, the magnetic properties, coloring power, and blackness of the magnetic toner can be easily set to desired values.
The content of the Ti component of the magnetic iron oxide is preferably 0.30 mass% or more and 5.00 mass% or less with respect to the entire magnetic iron oxide in terms of Ti element. More preferably, it is 0.30 mass% or more and 4.00 mass% or less, More preferably, it is 0.30 mass% or more and 3.00 mass% or less. By setting it within this range, it is easy to impart sufficient magnetization to the magnetic toner, and fog and the like are easily suppressed.
The content of the Al component in the magnetic iron oxide is preferably 0.10% by mass or more and 3.00% by mass or less with respect to the whole magnetic iron oxide in terms of Al element. The content is more preferably 0.10% by mass or more and 2.50% by mass or less, and further preferably 0.10% by mass or more and 2.00% by mass or less. By setting it as this range, it is easy to sharpen the particle size distribution of the magnetic iron oxide and to easily increase the blackness of the image.
In the magnetic iron oxide, the content of the Si component is preferably 0.10% by mass or more and 5.00% by mass or less based on the whole magnetic iron oxide in terms of Si element. More preferably, it is 0.10 mass% or more and 4.00 mass% or less, More preferably, it is 0.15 mass% or more and 3.50 mass% or less. By setting it within this range, it becomes easy to suppress the phenomenon that the charge amount becomes high in a low temperature and low humidity environment, and it is easy to suppress a decrease in image density caused by charging.

(1) When the magnetic iron oxide is introduced into an alkaline aqueous solution and the Al component contained in the magnetic iron oxide is eluted with the alkaline aqueous solution, the ratio of the amount of the Al component eluted is the total Al contained in the magnetic iron oxide. It is preferably 50% or more and 95% or less of the component amount.
When magnetic iron oxide is added to an alkaline aqueous solution, the Fe component and the Ti component are hardly eluted, and the Al component of the outermost layer is eluted. That is, it is considered that Al in the deep part from the surface of the magnetic iron oxide is not dissolved, and only Al existing in the outermost layer is dissolved. Therefore, when the magnetic iron oxide is put into an alkaline aqueous solution and the Al component contained in the magnetic iron oxide is eluted with the alkaline aqueous solution, the amount of Al component eluted is the amount of Al component in the outermost layer of magnetic iron oxide. It is thought to mean.
Then, when the magnetic iron oxide is put into an alkaline aqueous solution and the Al component contained in the magnetic iron oxide is eluted with the alkaline aqueous solution, the ratio of the Al component amount (the Al component amount of the outermost layer) eluted into the magnetic iron oxide is The V _EtA / v _EtA can be adjusted to the above range by _{setting the} total Al content to 50% or more and 95% or less. The reason for this is not fully understood, but the dispersibility of the release agent can be controlled by the amount of Al component present in the outermost layer of magnetic iron oxide.
That is, from the viewpoint of controlling the dispersibility of the release agent, the amount of Al component eluted when the Al component contained in the magnetic iron oxide is eluted with the alkaline aqueous solution (the Al amount of the outermost layer) is 0.1. It is preferable that they are mass% or more and 3.0 mass% or less.

(2) The magnetic iron oxide after the Al component contained in the magnetic iron oxide is eluted with the alkaline aqueous solution is further dissolved in an acid aqueous solution to obtain a solution, and the solution containing all the magnetic iron oxide is dissolved in the solution. When the amount of Fe element contained is the total amount of Fe element, a solution in which the magnetic iron oxide is dissolved until 10% by mass of the total amount of Fe element is present in the solution (hereinafter, Fe element dissolution rate: 10 mass) The total amount of Al components contained in (1) and the amount of Al components eluted in (1) is 95% or more and 100% or less of the total amount of Al components contained in the magnetic iron oxide. Is preferred.
In other words, the Al component is preferably present in the outermost layer and the intermediate layer of magnetic iron oxide, and the Al component is preferably not present in the central portion of the magnetic iron oxide. By not containing an Al component in the central portion of the magnetic iron oxide, magnetic iron oxide having a small particle size is hardly generated, and the blackness of the image is easily increased.
(3) The magnetic iron oxide in the present invention contains the Fe element dissolution rate of 10% by mass, and the ratio of the Ti component amount of the Ti element equivalent value to the Al element equivalent value of the Ti component amount (Ti component amount) The Ti element equivalent value / Al component equivalent value) is preferably 2.0 or more and 30.0 or less. By setting this range, the resistance value of the magnetic iron oxide can be easily increased, and the problem of unstable charging in the magnetic toner is less likely to occur.

The magnetic iron oxide of the present invention is a Si component that is eluted when the magnetic iron oxide is poured into an alkaline aqueous solution having the same composition as the above (1) and the Si component contained in the magnetic iron oxide is eluted with the alkaline aqueous solution. The proportion of the amount is preferably 5.0% or more and 30.0% or less, more preferably 8.0% or more and 27.0% or less of the total Si component amount contained in the magnetic iron oxide, and more preferably 10%. More preferably, it is 0.0% or more and 25.0% or less.
When the ratio of the amount of Si component eluted in the outermost alkaline aqueous solution of magnetic iron oxide is within the above range with respect to the total amount of Si component contained in the magnetic iron oxide, the magnetic iron oxide is likely to have a high resistance. Furthermore, it is easy to increase the affinity between magnetic iron oxide and a binder resin containing polyester as a main component, and it is easy to achieve good dispersibility of the magnetic iron oxide fine particles in the magnetic toner particles.
Further, when the magnetic iron oxide is put into an alkaline aqueous solution having the same composition as the above (1), and the Si component contained in the magnetic iron oxide is eluted with the alkaline aqueous solution, the amount of Si component eluted (Si on the outermost layer) The amount is preferably 0.20% by mass or more and 1.00% by mass or less. By setting the amount of Si in the outermost layer within this range, it is easy to control the exposure of the magnetic iron oxide on the magnetic toner surface.
Further, the ratio of the Ti element equivalent value of the Ti component amount contained in the 10 mass% Fe element dissolution rate solution to the Si element equivalent value of the Si component amount (Ti element equivalent value of Ti component amount / Si component amount) Of Si element) (hereinafter also simply referred to as [Ti / Si]), that is, the ratio of Ti amount / Si amount in the intermediate layer is preferably 1.0 or more and 5.0 or less, more preferably It is 1.2 or more and 4.5 or less. When [Ti / Si] is in the above range, it is easy to improve the dispersibility of the magnetic iron oxide in the magnetic toner and to obtain good charging characteristics.

The magnetic toner of the present invention has a magnetization of 12 Am ² / kg in an external magnetic field of 79.6 kA / m.
It is preferably 80 Am ² / kg or less. The reason for defining with an external magnetic field of 79.6 kA / m is that a magnetic environment on the developing sleeve is assumed. When the magnetization is within the above range, it is easy to achieve both image density and fog. Furthermore, good durability is easily obtained.
The magnetic iron oxide used in the magnetic toner of the present invention is composed of spherical particles in which magnetic iron oxide fine particles are mainly formed with curved surfaces having no smooth surface, as observed by transmission electron micrographs. Is preferable.
The magnetic iron oxide used in the magnetic toner of the present invention preferably has a BET specific surface area of 5.0 m ² / g or more and 15.0 m ² / g or less, more preferably 6. It is 0 m ² / g or more and 13.0 m ² / g or less. By setting the BET specific surface area within the above range, it is easy to optimize the moisture adsorption amount of magnetic iron oxide that affects the charging property of the magnetic toner.
As magnetic characteristics of the magnetic iron oxide used in the magnetic toner of the present invention, the saturation magnetization under a magnetic field of 795.8 kA / m is preferably 10.0 to 200.0 Am ² / kg, more preferably 60. 0~100.0Am a ² / kg, preferably residual magnetization is 1.0~100.0Am ² / kg, more preferably from 2.0~20.0Am ² / kg, a coercive force of 1 It is preferable that it is 0.0-30.0 kA / m, More preferably, it is 2.0-15.0 kA / m. By having such a magnetic characteristic, it is possible to obtain good developability in which image density and fog are balanced.
The specific gravity of the magnetic iron oxide used in the present invention is preferably 3.00 g / cm ³ or more and 6.00 g / cm ³ or less. By being within this range, it is easier to satisfy the desired magnetization and further suppress the magnetic iron oxide bias.
In the magnetic toner of the present invention, the content of the magnetic iron oxide is preferably 30 parts by mass or more and 120 parts by mass with respect to 100 parts by mass of the binder resin, more preferably the magnetic iron oxide. 45 parts by mass or more and 100 parts by mass or less. By making it within the above range, it is easier to achieve both the coherence of the magnetic toner and the image density.

Although illustrated about the manufacturing method of the magnetic iron oxide used by this invention, it is not limited to the following manufacturing methods.
(First step)
An aqueous solution of ferrous sulfate, sodium silicate, sodium hydroxide and water are mixed to prepare a mixed solution. While maintaining the temperature of this mixed solution at 90 ° C. and maintaining the pH at 6 to 9, air is blown to wet-oxidize the ferrous hydroxide produced in the liquid. The formation of the central region of the magnetite particles produced when 70 to 90% of ferrous hydroxide is consumed with respect to the initial amount is confirmed.
(Second step)
During the course of the first step, the progress of the oxidation reaction is examined by examining the concentration of unreacted ferrous hydroxide in the liquid. Identify when ~ 90% consumed. At the specified time, a ferrous sulfate aqueous solution having the same concentration as that used in the first step, titanyl sulfate, and aluminum sulfate are added to the solution, and water is further added to adjust the liquid volume. To this, sodium hydroxide is added to adjust the pH of the solution to 9-12. In this solution, the sodium silicate added in the first step remains. Air is blown at a liquid temperature of 90 ° C. to advance wet oxidation and generate an intermediate region.
(Third process)
During the second step, when 95 to 99% of the unreacted ferrous hydroxide in the liquid is consumed, the blowing of air is stopped, and sodium silicate and aluminum sulfate are added to the solution. Added. Further, dilute sulfuric acid is added to adjust the pH of the solution to 5-9.
(Fourth process)
The magnetite particles thus obtained are washed and filtered by a conventional method, further dried and then pulverized to obtain the magnetic iron oxide used in the present invention.
The magnetic iron oxide used in the present invention is particularly preferably In the first step, ferrous hydroxide moves to the second step when 70 to 90% of the initial amount is consumed,
2. In the second step, titanyl sulfate is added, the amount of titanyl sulfate and aluminum sulfate at that time is appropriately adjusted, and
3. Adjust the pH in the second step to 9-12,
4). When ferrous hydroxide is consumed 95 to 99%, the process proceeds to the third step.
5. In the third step, the above properties can be imparted by appropriately adjusting the addition amounts of sodium silicate and aluminum sulfate.

(Preparation of magnetic iron oxide fine particle dispersion)
The magnetic iron oxide fine particle dispersion can be obtained by dispersing magnetic iron oxide fine particles in an aqueous medium.
As the aqueous medium, the same one as in the preparation of the binder resin fine particle dispersion can be used, and basically ion-exchanged water is used. It doesn't matter.
Further, in order to keep the magnetic iron oxide fine particle dispersion stably in a dispersed state, a dispersant can be used similarly to the preparation of the binder resin fine particle dispersion, and a surfactant can be used as the dispersant. .
As a dispersion method to the medium, for example, a general dispersion method such as a rotary shear type homogenizer, a ball mill having a medium, a sand mill, or a dyno mill can be used, and the method is not limited at all.

(Release agent)
Examples of the release agent (wax) used in the present invention include the following. Low molecular weight polyethylene, low molecular weight polypropylene, low molecular weight olefin copolymer, aliphatic hydrocarbon wax such as microcrystalline wax, paraffin wax, Fischer-Tropsch wax; oxide of aliphatic hydrocarbon wax such as oxidized polyethylene wax; fat A wax mainly composed of a fatty acid ester such as an aromatic hydrocarbon ester wax; and a part or all of a fatty acid ester such as a deoxidized carnauba wax deoxidized. Partially esterified products of fatty acids and polyhydric alcohols such as behenic acid monoglyceride; methyl ester compounds having a hydroxyl group obtained by hydrogenating vegetable oils and the like. Also, ester wax, hydrocarbon wax, and the like can be used.
The release agent particularly preferably used in the present invention is, in the emulsion aggregation method, easy preparation of the release agent dispersion, easy incorporation into the magnetic toner, and easy exudation from the magnetic toner during fixing. In view of releasability, polyethylene wax is particularly preferable.

In the present invention, the content of the release agent in the magnetic toner is 5.0% by mass or more and 20.0% by mass or less, more preferably 5.0% by mass or more and 15.0% by mass or less. By setting it within this range, the durability and chargeability of the magnetic toner and the release effect of the release agent can be easily improved.
In the present invention, the release agent preferably has an endothermic peak in a temperature range of 60 ° C. or higher and 90 ° C. or lower in DSC measurement. By setting it within this range, the wax is easily melted at a low temperature, and a release effect is easily exhibited. As a result, it is easy to achieve both low temperature fixability and offset resistance.

(Preparation of release agent fine particle dispersion)
As the release agent fine particle dispersion, it is preferable to use a phase inversion emulsification method as in the preparation of the binder resin fine particle dispersion. As the organic solvent for dissolving the release agent, the same organic resin as the binder resin fine particle dispersion can be used. The medium of the release agent fine particle dispersion basically uses ion-exchanged water as in the case of the binder resin fine particle dispersion, but may contain a water-soluble organic solvent to the extent that oil droplets are not destroyed. Absent.
Further, in order to keep the release agent fine particle dispersion stably in a dispersed state, a dispersant similar to the preparation of the binder resin fine particle dispersion can be used, and a surfactant can be used as the dispersant. .
As a dispersion method to the medium, for example, a general dispersion method such as a rotary shear type homogenizer, a ball mill having a medium, a sand mill, or a dyno mill can be used, and the method is not limited at all.

In the magnetic toner of the present invention, the magnetic iron oxide fine particles can be used in combination with a colorant. A well-known thing can be used as said coloring agent. Examples of the black pigment include carbon black, aniline black, copper oxide, manganese dioxide, black titanium oxide, nonmagnetic ferrite, magnetic ferrite, activated carbon, and magnetite.
As the colorant, a dye can be used. Examples of the dye that can be used include various dyes such as basic, acidic, dispersed, and direct dyes, such as nigrosine. Moreover, these can be used individually or in mixture, and also in the state of a solid solution.
These colorants are dispersed by a known method. For example, a rotary shearing type homogenizer, a sand mill, a ball mill and the like can be mentioned.
The colorant such as carbon black, together with the magnetic iron oxide fine particles, uses a polar surfactant and is dispersed in an aqueous medium by the homogenizer. Therefore, the colorant is selected from the viewpoint of dispersibility in the magnetic toner. It is preferred that The addition amount of the colorant is preferably 3 to 50 parts by mass with respect to 100 parts by mass of the binder resin.

In the present invention, a charge control agent can be used as necessary. The charge control agent may be contained in the magnetic toner particles containing the binder resin and magnetic iron oxide, or may be contained on the surface of the magnetic toner particles.
The charge control agent is added and dispersed. The charge control agent is added and dispersed as charge control agent particles when forming the aggregated particles, and the charge control agent is added and dispersed when the binder resin fine particles are prepared. And a method of binding a charge control agent in the molecule of the resin constituting the binder resin fine particles.
The content of the charge control agent is preferably 0.01 parts by mass or more and 0.80 parts by mass or less with respect to 100 parts by mass of the magnetic toner particles. By making it within this range, it is easy to prevent charge-up under low temperature and low humidity, and it is easy to improve the charge retention ability under high temperature and high humidity.
Examples of the charge control agent include the following. Nigrosine dye, triphenylmethane dye, metal-containing azo complex dye, molybdate chelate pigment, rhodamine dye, alkoxy amine, quaternary ammonium salt (including fluorine-modified quaternary ammonium salt), alkylamide, phosphorus simple substance Or a compound, a simple substance or compound of tungsten, a fluorine-based activator, a metal salt of salicylic acid, and a metal salt of a salicylic acid derivative.
Specific examples include the following. Bontron N-03 of nigrosine dye, Bontron P-51 of quaternary ammonium salt, Bontron S-34 of metal-containing azo dye, E-82 of oxynaphthoic acid metal complex, E-84 of salicylic acid metal complex, Phenolic condensate E-89 (above, manufactured by Orient Chemical Co., Ltd.), quaternary ammonium salt molybdenum complex TP-302, TP-415 (above, manufactured by Hodogaya Chemical Co., Ltd.), quaternary ammonium salt Copy charge PSY VP2038, copy blue PR of triphenylmethane derivative, copy charge of quaternary ammonium salt NEG VP2036, copy charge NX
VP434 (above, manufactured by Hoechst), LRA-901, LR-147 (manufactured by Nippon Carlit Co., Ltd.), copper phthalocyanine, perylene, quinacridone, azo pigment, other sulfonic acid groups, carboxyl groups and quaternary ammonium salts A polymer compound having a functional group such as

  Moreover, in this invention, charge control resin can be used as needed. Examples of the charge control resin include resins having a chargeable functional group such as a carboxyl group, a phenolic hydroxyl group, a naphtholic hydroxyl group, a sulfonic acid group, an amino group, and a quaternary ammonium salt. The content is preferably 0.2 to 5 parts by mass with respect to 100 parts by mass of the binder resin.

The method for producing magnetic toner particles of the present invention includes the following dispersion step, aggregation step, and melting step. Moreover, the adhesion process is included as needed.
(Dispersion process)
The dispersion step is a step of dispersing at least the binder resin fine particles, the magnetic iron oxide fine particles, and the release agent fine particles in the medium in order to obtain the magnetic toner particles of the present invention.
As a dispersion method to the medium, for example, a general dispersion method such as a rotary shear type homogenizer, a ball mill having a medium, a sand mill, or a dyno mill can be used, and the method is not limited at all.
(Aggregation process)
The aggregation step includes at least a binder resin fine particle dispersion in which binder resin fine particles are dispersed, a magnetic iron oxide fine particle dispersion in which magnetic iron oxide fine particles are dispersed, and a release agent in which release agent fine particles are dispersed. In this step, the fine particle dispersion is mixed and heated to a temperature not higher than the glass transition point of the binder resin fine particles to form aggregated particles, thereby preparing an aggregated particle dispersion.
The volume average particle size of the binder resin fine particles, magnetic iron oxide fine particles, and release agent fine particles is usually 1 μm or less, and preferably 0.01 to 1 μm. When the volume average particle size exceeds 1 μm, the particle size distribution of the finally obtained toner is broadened or free particles are generated, which tends to cause a decrease in performance and reliability. On the other hand, when the volume average particle size is within the above range, the above-described drawbacks are not caused, and uneven distribution among the toners is reduced, the dispersion of each material in the toner becomes better, and variations in performance and reliability are reduced. This is advantageous.
In the aggregation step, aggregated particles are formed in the mixed solution to prepare an aggregated particle dispersion. The agglomerated particles can be formed in the mixed solution by adding, for example, a pH adjusting agent, a flocculant, and a stabilizer to the mixed solution and mixing them, and appropriately adding temperature, mechanical power and the like.
Examples of the pH adjuster include alkalis such as ammonia and sodium hydroxide, and acids such as nitric acid and citric acid. As the flocculant, polyaluminum chloride (PAC), cetylpyridinium bromide, dialkylbenzenealkylaluminum chloride, dodecylbenzyltriethylammonium chloride, alkylbenzylmethylammonium chloride, lauryltrimethylammonium chloride, alkylbenzyldimethylammonium bromide, benzalkonium chloride, C12, C15, C17 trimethylammonium bromide, and mixtures thereof are included.
Examples of the stabilizer mainly include a polar surfactant itself or an aqueous medium containing the polar surfactant. For example, when the polar surfactant contained in the aqueous dispersion is anionic, a cationic one can be selected as the stabilizer.
The addition / mixing of the flocculant and the like is preferably performed at a temperature not higher than the glass transition point of the resin contained in the mixed solution. When the mixing is performed under this temperature condition, aggregation proceeds in a stable state. The mixing can be performed using, for example, a known mixing device, a homogenizer, a mixer and the like.
The average particle size of the aggregated particles formed here is not particularly limited, but is usually controlled to be about the same as the average particle size of the toner to be obtained. The control can be easily performed, for example, by appropriately setting and changing the temperature and the stirring and mixing conditions. Through the above-described aggregated particle forming step, aggregated particles having an average particle size substantially the same as the average particle size of the toner are formed, and an aggregated particle dispersion liquid in which the aggregated particles are dispersed is prepared.
(Adhesion process)
The attaching step is a step of adding and mixing a fine particle dispersion in which fine particles are dispersed in the aggregated particle dispersion to form the attached particles by attaching the fine particles to the aggregated particles. The adhering step is preferably performed between the aggregation step and a melting step described later, but may not be performed. Examples of the fine particles include resin-containing fine particles, magnetic iron oxide fine particles, release agent fine particles, and charge control agent fine particles.
The fine particle dispersion is prepared, for example, by dispersing the fine particles in an aqueous medium to which an ionic surfactant or the like is added and mixed.
In the attaching step, the fine particle dispersion is added and mixed in the aggregated particle dispersion prepared in the aggregating step, and the fine particles are attached to the aggregated particles to form attached particles. In the present invention, the number of times this adhesion step is performed may be one or more times. In the former, only one layer of the fine particles is formed on the surface of the aggregated particles, whereas in the latter, two or more layers of the fine particles are sequentially formed on the surface of the aggregated particles. Therefore, the latter case is advantageous in that a magnetic toner having a complicated and precise hierarchical structure can be obtained, and a desired function can be imparted to the magnetic toner. When the adhesion step is performed a plurality of times, any combination of the fine particles to be first adhered to the aggregated particles and the fine particles to be adhered to the subsequent particles may be of any kind, depending on the use and purpose of the magnetic toner. It can be selected appropriately. In addition, when the adhesion step is performed a plurality of times, each time the fine particles are added and mixed, the dispersion containing the fine particles and the aggregated particles is at a temperature below the glass transition point of the binder resin used in the aggregation step. An embodiment in which heating is performed is preferable, and an embodiment in which the heating temperature is increased stepwise is more preferable. This is advantageous in that the generation of free particles can be suppressed. As described above, a magnetic toner having desired characteristics can be freely designed and manufactured by attaching appropriately selected fine particles to the aggregated particles in the attaching step.
(Melting process)
The melting step is a step of heating and fusing the aggregated particles. Before entering the melting step, the pH adjuster, the polar surfactant, the nonpolar surfactant, and the like can be appropriately added to prevent fusion between toner particles.
The heating temperature may be from the glass transition temperature of the resin contained in the aggregated particles to the decomposition temperature of the resin. Therefore, the temperature of the heating varies depending on the binder resin fine particles and the resin type of the binder resin fine particles and cannot be generally defined, but is generally included in the aggregated particles or the adhered particles. The glass transition temperature of the resin to be obtained is 140 ° C. In addition, the said heating can be performed using a publicly known heating apparatus and instrument.
As the melting time, a short time is sufficient if the heating temperature is high, and a long time is required if the heating temperature is low. That is, the melting time depends on the heating temperature and cannot be defined in general, but is generally 30 minutes to 10 hours.
(External addition process)
The magnetic toner particles obtained by the above production method are prepared by externally adding hydrophobic inorganic fine particles to supplement fluidity, developability, chargeability, and cleaning properties.
The primary average particle diameter of the hydrophobic inorganic fine particles is preferably 5 nm or more and 2 μm or less, and particularly preferably 5 nm or more and 500 nm or less. Further, BET specific surface area, 20 m ² / g or more 500m is preferably ² / g or less. By making it within this range, it is easy to improve the durability, low-temperature fixability and chargeability of the magnetic toner.
The use ratio of the hydrophobic inorganic fine particles is preferably 0.01% by mass or more and 5% by mass or less, and particularly preferably 0.01% by mass or more and 2.0% by mass or less of the magnetic toner particles.
The hydrophobic inorganic fine particles may be used in combination with a plurality of types of hydrophobic inorganic fine particles as necessary. Further, if necessary, polymer fine particles may be used in combination.
Specific examples of the hydrophobic inorganic fine particles include the following. Silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, tin oxide, silica sand, clay, mica, wollastonite, diatomaceous earth, chromium oxide, cerium oxide, bengara , Antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, silicon nitride and the like.
On the other hand, specific examples of the polymer fine particles include the following. Polystyrene particles obtained by soap-free emulsion polymerization, suspension polymerization and dispersion polymerization, methacrylic acid ester and acrylic acid ester copolymer, and polymer particles such as silicone, benzoguanamine and nylon.
The hydrophobic inorganic fine particles used in the present invention can be surface treated with a surface treatment agent to further increase the hydrophobicity, thereby preventing deterioration of the flow characteristics and charging characteristics of the magnetic toner even under high humidity.
For example, preferable surface treatment agents include the following. Silane coupling agents, silylating agents, silane coupling agents having an alkyl fluoride group, organic titanate coupling agents, aluminum coupling agents, silicone oils, modified silicone oils, and the like.
Examples of the cleaning property improver for removing the magnetic toner after transfer remaining on the photoreceptor or the primary transfer medium include the following. Polymer fine particles produced by soap-free emulsion polymerization such as fatty acid metal salts such as zinc stearate, calcium stearate and stearic acid, polymethyl methacrylate fine particles, polystyrene fine particles and the like.
The magnetic toner of the present invention preferably has a weight average particle diameter (D4) of 3.0 to 10.0 μm, more preferably 3.5 to 9.0 μm, and still more preferably 4.0 to 4.0. 8.0 μm. When the weight average particle diameter (D4) of the magnetic toner is in the above range, it is easy to prevent fogging and scattering, contribute to high image quality, and it is possible to suppress toner consumption. .

The method for measuring various physical property data in the present invention is described in detail below.
<1> Ethyl acetate precipitation test The ethyl acetate precipitation test of magnetic iron oxide is described below.
(1) 20 g of magnetic iron oxide and 30 g of ethyl acetate are placed in a stoppered pressure-resistant glass bottle, and magnetic iron oxide is dispersed in ethyl acetate by stirring for 5 minutes with a paint shaker to obtain a slurry. (2) Put 20 g of the slurry and 20 g of ethyl acetate into a graduated cylinder, and close the mouth of the graduated cylinder with a rubber stopper. As the graduated cylinder, a JIS R-3504 standard-acquired 50 mL graduated cylinder is used. As the measuring cylinder, for example, 3Z manufactured by Shibata Kagaku can be used.
(3) Shake the graduated cylinder with rubber stopper by hand for 10 seconds and place it on a horizontal table.
At the same time as standing, start the stopwatch and start timing. After standing, magnetic iron oxide precipitates over time, and the boundary between the supernatant portion of ethyl acetate and the precipitated portion of magnetic iron oxide can be visually confirmed.
(4) Ten minutes after standing, the boundary surface between the air above the graduated cylinder and the liquid surface of the supernatant portion, and the boundary surface between the supernatant portion and the sedimented portion are read from the scale of the graduated cylinder. The volume read from the interface between the air at the top of the graduated cylinder and the liquid level of the supernatant (total volume up to the liquid level of ethyl acetate) is _defined as v _EtA, and the volume read from the interface between the supernatant and the precipitate (
Sedimentation volume) is _designated as V _EtA . In addition, when the boundary surface of a sedimentation part is rough, the average of a peak and a valley is drawn and measured.
(5) The operations of (1) to (4) are repeated, and the arithmetic average value of the three measurements is set as v _EtA and V _EtA , and the ratio of V _EtA and v _EtA and V _EtA / v _EtA are calculated. .

<2> except for changing the isopropyl alcohol precipitation test ethyl acetate in isopropyl alcohol in the same manner as ethyl acetate precipitation test determines the V _IPA, the ratio of V _IPA and V _EtA, calculates a V _IPA / V _EtA.

<3> A method for quantifying the amount of Al component or Si component eluted when an Al component or Si component contained in magnetic iron oxide is eluted with an alkaline aqueous solution.
(1) Preparation of sample Weigh 0.9 g of magnetic iron oxide and place it in a methylpentene beaker. Next, 25 ml of 1 mol / L NaOH is weighed and put into a beaker. The rotor is put in a beaker, covered, heated and stirred (liquid temperature 70 ° C.) for 4 hours on a hot stirrer, and then allowed to cool. After standing to cool, all the magnetic iron oxide, including the magnetic iron oxide adhering to the rotor, is poured into the graduated cylinder with pure water. After adjusting the liquid volume to 125 ml with pure water, transfer to a beaker and stir well. Thereafter, a beaker is left on the magnet, and the magnetic iron oxide is allowed to settle until the supernatant becomes transparent. After sedimentation, the supernatant is filtered to obtain a filtrate.
(2) Measuring method The obtained filtrate is sprayed in inductively coupled plasma of an ICP emission photometric analyzer (trade name: ICPS2000, manufacturer: Shimadzu Corporation), wavelength 288.16 nm (Si), wavelength 396.15 nm (Al). By measuring the luminescence intensity at and comparing it with the luminescence intensity of a calibration curve solution having a known concentration, the Al element concentration (mg / L) and Si element concentration (mg / L) in the filtrate are quantified.
(3) Preparation method of the above calibration curve solution Add 100 g of NaOH, Si component, and Al component to a 100 mL polymeasuring flask, and make up to 100 mL with ion-exchanged water. Several levels of calibration curve solutions are prepared in the range of 50 mg / L] and the Al element concentration of the Al component is in the range of [0 to 40 mg / L].
(4) Formula The amount of Al component eluted when the Al component or Si component contained in magnetic iron oxide is eluted with the above alkaline aqueous solution (Al element conversion value: [mass%]) or Si component amount (Si element) Conversion value: [mass%]) is calculated from the following formula.
(Formula): Al component amount (Al element conversion value: [mass%]) or Si component amount (Si element conversion value: [mass%]) = (L × 0.125) / (S × 1000) × 100
L: concentration of each element obtained from ICP measurement value of each element (mg / L)
S: Mass of sample 0.9 (g)

<4> Quantitative determination method of each element contained in a 10 mass% Fe element dissolution rate solution (1) Preparation of sample After completion of sample preparation described in [(1) Sample preparation] in <3> above The magnetic iron oxide precipitated in the beaker, that is, the magnetic iron oxide after elution of the Al component or Si component contained in the magnetic iron oxide with an alkaline aqueous solution is collected and dried. 25 g of the obtained dried magnetic iron oxide is weighed and placed in a 5 L glass beaker. Next, 5 L of 0.5 mol / L H ₂ SO ₄ was added and stirred, and the temperature was gradually raised from room temperature to 80 ° C. in a water bath to gradually dissolve the magnetic iron oxide from the surface. Obtain a liquid. Here, in particular, when the amount of Fe element contained in the solution in which all of the magnetic iron oxide is dissolved is defined as the total amount of Fe element, the magnetic oxidation is performed until 10% by mass of the total amount of Fe element exists in the solution. A solution in which iron is dissolved (referred to as a solution containing 10% by mass of Fe element) is obtained. 25 ml of the resulting Fe element dissolution rate 10% by mass solution (slurry) is collected. The collected slurry is filtered through a 0.1 μm membrane filter to obtain a filtrate.
(2) Measuring method The obtained filtrate is sprayed in inductively coupled plasma of an ICP emission photometric analyzer (trade name: ICPS2000, manufacturer: Shimadzu Corporation), wavelength 288.16 nm (Si), wavelength 396.15 nm (Al ), The emission intensity at a wavelength of 334.94 nm (Ti) and a wavelength of 259.94 nm (Fe) is measured, and compared with the emission intensity of a calibration curve solution with a known concentration, the concentration of Si element in the filtrate ( mg / L), Ti element concentration (mg / L), Al element concentration (mg / L), and Fe element concentration (mg / L) are quantified.
(3) Preparation method of the above calibration curve solution To a 1000 mL polymer flask, add 51 g of H ₂ SO ₄ , Fe component, Si component, Al component, and Ti component, and make up to 1000 mL with ion-exchanged water. The Fe element concentration of the component is in the range of [100 to 4000 mg / L], and the Si element concentration of the Si component is [0 to 15].
0 mg / L], a calibration curve solution in which the Al element concentration of the Al component is in the range of [0 to 40 mg / L] and the Ti element concentration of the Ti component is in the range of [0 to 30 mg / L]. Make several levels.
(4) Calculation formula The amount of Si component (Si element conversion value: [mass%]) and Ti component amount (Ti element conversion value: [mass%]) contained in the 10 mass% Fe element dissolution rate solution. , Al component amount (Al element conversion value: [mass%]) and Fe component amount (Fe element conversion value: [mass%]) are calculated using the following equations.
(Formula): Si component amount (Si element conversion value: [mass%]), Ti component amount (Ti element conversion value: [mass%]), Al component amount (Al element conversion value: [mass%]), or Fe component amount (Fe element conversion value: [mass%])
= (L × 5) / (S × 1000) × 100
L: concentration of each element obtained from ICP measurement value of each element (mg / L)
S: Sample weight 25 (g)

<5> Total Si component amount contained in magnetic iron oxide (Si element conversion value [mass%]), Total Ti component amount (Ti element conversion value: [mass%]), or Total Al component amount (Al element conversion) Value: [mass%]) quantification method.
(1) Preparation of sample Weigh 1.00 g of magnetic iron oxide and place it in a 100 mL Teflon (registered trademark) beaker. Next, 10 mL of water and 16 mL of concentrated hydrochloric acid are added and then heated to dissolve all the magnetic iron oxide. After cooling, 4 mL of hydrofluoric acid (1 + 1) is added and left for 20 minutes. Next, the obtained solution was transferred to a 100 mL polymer flask, and a surfactant (trade name: Triton X [10 g / L]) was added to 1 m.
Add L and make up to 100 mL.
(2) Measurement method The sample solution prepared above is sprayed into an inductively coupled plasma of an ICP emission photometric analyzer (trade name: ICPS2000, manufacturer: Shimadzu Corporation), and a wavelength of 288.16 nm (Si), a wavelength of 396.15 nm ( Al), by measuring the emission intensity at a wavelength of 334.94 nm (Ti) and comparing it with the emission intensity of a calibration curve solution with a known concentration, Si element (mg / L) in the sample solution
, Ti element (mg / L) and Al element (mg / L) are quantified.
(3) Preparation method of the above calibration curve solution In a 1000 mL polymeas flask, 16 mL HCl, 4 mL HF (1 + 1), 1 mL surfactant (1% Triton X), 650 mg Fe, Si component, Al component, and The Ti component is added, and the volume is adjusted to 1000 mL with ion-exchanged water. The Si element concentration of the Si component, the Al element concentration of the Al component, and the Ti element concentration of the Ti component are in the range of [0 to 200 mg / L]. Prepare several levels of calibration curve.
(4) Calculation formula Total Si component amount (Si element conversion value [mass%]), total Ti component amount (Ti element conversion value: [mass%]), or total Al component amount (Al Element conversion value: [mass%]) is calculated using the following formula.
(Formula): Total Si component amount (Si element conversion value [mass%]), Total Ti component amount (Ti element conversion value: [mass%]), or Total Al component amount (Al element conversion value: [mass%]) )
= (L × 0.1) / (S × 1000) × 100
L: concentration of each element obtained from ICP measurement value of each element (mg / L)
S: Sample mass 1.00 (g)

The (total) Ti component amount (Ti element conversion value: [mass%]) or (total) Al component amount (Al element conversion value: [mass%]) contained in the magnetic iron oxide used in the present invention. ) Is calculated by the method <5> above.
The magnetic iron oxide used in the present invention is charged into an alkaline aqueous solution, and the Al component amount eluted when the Al component contained in the magnetic iron oxide is eluted with the alkaline aqueous solution, the total amount contained in the magnetic iron oxide. The magnetic iron oxide of the amount of Si component eluted when the ratio (%) to the amount of Al component or magnetic iron oxide is added to an alkaline aqueous solution and the Si component contained in the magnetic iron oxide is eluted with the alkaline aqueous solution. The ratio (%) to the total amount of Si components contained in is calculated from the results of <3> and <5> above.
In the present invention, the magnetic iron oxide after eluting the Al component contained in the magnetic iron oxide with an alkaline aqueous solution is further dissolved with an aqueous acid solution to obtain a solution, and the solution in which all the magnetic iron oxide is dissolved is obtained. When the Fe element amount contained in the total Fe element amount is 10% by mass of the total Fe element amount, the dissolved solution of the magnetic iron oxide until the 10% by mass of the total Fe element amount exists in the dissolved solution (Fe element dissolution rate 10% by mass solution) ) And the total amount of the Al component contained in the magnetic solution and the amount of the Al component eluted when the magnetic iron oxide is poured into the alkaline aqueous solution and the Al component contained in the magnetic iron oxide is eluted with the alkaline aqueous solution. The ratio (%) to the total amount of Al components contained in iron oxide is calculated from the results of <3>, <4>, and <5>.
The ratio of Ti element amount converted to Ti element amount contained in the 10% by mass Fe element dissolution rate used in the present invention to the ratio of Al component amount to Al element converted value (Ti component amount converted to Ti element amount) Value / Al component conversion value of Al component) or the ratio of Ti element conversion value of Ti component amount to the Si element conversion value of Si component amount contained in the 10 mass% Fe element dissolution rate solution ( (Ti element equivalent value of Ti component amount / Si element equivalent value of Si component amount) is calculated from the result of <4> above.

<7> Method for Measuring Specific Surface Area of Magnetic Iron Oxide Specific Surface Area Measuring Device Auto Soap 1 (manufactured by Yuasa Ionics) is used to adsorb nitrogen gas on the sample surface and calculate the specific surface area using the BET multipoint method. .

<8> Method for Measuring Magnetic Properties of Magnetic Iron Oxide and Magnetic Toner Magnetic properties of magnetic iron oxide were measured using a vibrating sample magnetometer (VSM-3S-15, manufactured by Toei Kogyo Co., Ltd.) and an external magnetic field of 795.8 kA. Measured under / m.
On the other hand, the measurement method of the magnetic properties of the magnetic toner is the same as the measurement method of the magnetic properties of the magnetic iron oxide except that the external magnetic field is changed to 79.6 kA / m in the measurement method of the magnetic properties of the magnetic iron oxide. taking measurement.

<9> Method for Measuring Glass Transition Point of Binder Resin The glass transition point (Tg) of the binder resin is measured according to ASTM D3418-82 using a differential scanning calorimeter “Q1000” (manufactured by TA Instruments). To do. The measurement is performed using a DSC curve measured when the temperature is raised at a temperature rate of 10 ° C./min after raising and lowering the temperature once and taking a previous history. In this temperature rising process, a specific heat change is obtained in the temperature range of 40 to 100 ° C. At this time, the intersection of the intermediate point line of the baseline before and after the change in specific heat and the differential heat curve is defined as the glass transition point (Tg) of the toner and the binder resin in the present invention.

<10> Method for Measuring Weight Average Particle Size (D4) of Magnetic Toner The weight average particle size (D4) of the toner is calculated as follows. As a measuring device, a precise particle size distribution measuring device “Coulter Counter Multisizer 3” (registered trademark, manufactured by Beckman Coulter, Inc.) using a pore electrical resistance method equipped with a 100 μm aperture tube is used. For setting the measurement conditions and analyzing the measurement data, the attached dedicated software “Beckman Coulter Multisizer 3 Version 3.51” (manufactured by Beckman Coulter, Inc.) is used. Note that the measurement is performed with 25,000 effective measurement channels.
As the electrolytic aqueous solution used for the measurement, special grade sodium chloride is dissolved in ion-exchanged water so as to have a concentration of about 1% by mass, for example, “ISOTON II” (manufactured by Beckman Coulter, Inc.) can be used.
Prior to measurement and analysis, the dedicated software is set as follows.
On the “Change Standard Measurement Method (SOM)” screen of the dedicated software, set the total count in the control mode to 50,000 particles, set the number of measurements once, and set the Kd value to “standard particles 10.0 μm” (Beckman Coulter Set the value obtained using By pressing the “Threshold / Noise Level Measurement Button”, the threshold and noise level are automatically set. In addition, the current is set to 1600 μA, the gain is set to 2, the electrolyte is set to ISOTON II, and the “aperture tube flush after measurement” is checked.
In the “Pulse to particle size conversion setting” screen of the dedicated software, the bin interval is set to logarithmic particle size, the particle size bin is set to 256 particle size bin, and the particle size range is set to 2 μm to 60 μm.
The specific measurement method is as follows.
(1) About 200 ml of the electrolytic aqueous solution is put in a glass 250 ml round bottom beaker exclusively for Multisizer 3, set on a sample stand, and the stirrer rod is stirred counterclockwise at 24 rotations / second. Then, the dirt and bubbles in the aperture tube are removed by the “aperture flush” function of the dedicated software.
(2) About 30 ml of the electrolytic aqueous solution is put into a glass 100 ml flat bottom beaker. In this, "Contaminone N" (nonionic surfactant, anionic surfactant, 10% by weight aqueous solution of neutral detergent for pH7 precision measuring instrument cleaning, made by organic builder, manufactured by Wako Pure Chemical Industries, Ltd. About 0.3 ml of a diluted solution obtained by diluting 3) with ion-exchanged water is added.
(3) Two oscillators with an oscillation frequency of 50 kHz are incorporated with the phase shifted by 180 degrees, and an ultrasonic disperser “Ultrasonic Dissipation System Tetora 150” (manufactured by Nikkaki Bios Co., Ltd.) having an electrical output of 120 W is prepared. About 3.3 l of ion-exchanged water is placed in the water tank of the ultrasonic disperser, and about 2 ml of Contaminone N is added to the water tank.
(4) The beaker of (2) is set in the beaker fixing hole of the ultrasonic disperser, and the ultrasonic disperser is operated. And the height position of a beaker is adjusted so that the resonance state of the liquid level of the electrolyte solution in a beaker may become the maximum.
(5) In a state where the electrolytic aqueous solution in the beaker of (4) is irradiated with ultrasonic waves, about 10 mg of toner is added to the electrolytic aqueous solution little by little and dispersed. Then, the ultrasonic dispersion process is continued for another 60 seconds. In the ultrasonic dispersion, the temperature of the water tank is appropriately adjusted so as to be 10 ° C. or higher and 40 ° C. or lower.
(6) To the round bottom beaker of (1) installed in the sample stand, the electrolyte solution of (5) in which the toner is dispersed is dropped using a pipette, and the measurement concentration is adjusted to about 5%. . The measurement is performed until the number of measured particles reaches 50,000.
(7) The measurement data is analyzed with the dedicated software attached to the apparatus, and the weight average particle diameter (D4) is calculated. The “average diameter” on the “analysis / volume statistics (arithmetic average)” screen when the graph / volume% is set by the dedicated software is the weight average particle diameter (D4).

EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples. In addition, the number of parts in the following composition is part by mass unless otherwise specified.
(Production example of magnetic iron oxide)
[Step 1]
A mixture of 8.0 L of ferrous sulfate containing 1.9 mol / L of Fe ²⁺ , 75 g of sodium silicate having a Si grade of 13.4% and 1.06 kg of sodium hydroxide is added, and the total amount is added with ion-exchanged water. Was 16.2 L. While maintaining the temperature of this solution at 90 ° C. and maintaining the pH at 6-9, air was blown at 2 L / min to wet-oxidize the ferrous hydroxide produced in the liquid. The formation of the magnetite central region was confirmed when 90% of the ferrous hydroxide was consumed relative to the initial amount. This central region contained Si element.
[Step 2]
During the course of step 1, the progress of the oxidation reaction is examined by examining the concentration of unreacted ferrous hydroxide in the solution. Ferrous hydroxide is consumed by 90% of the initial amount. At that time, 0.9 L of ferrous sulfate aqueous solution having the same concentration as that used in Step 1 and 70 g of titanyl sulfate having a Ti grade of 20.0% were added to the solution, and ion exchange water was further added to reduce the amount of the solution. 18L. In addition, sodium hydroxide was added to adjust the pH of the solution to 9-12. In this solution, the sodium silicate added in Step 1 remained. Air was blown at a liquid temperature of 90 ° C. at a rate of 1 L / min to advance wet oxidation, thereby generating an intermediate region composed of magnetite containing Si element and Ti element.
[Step 3]
In the middle of performing the above-mentioned step 2, when 95% of the unreacted ferrous hydroxide in the liquid is consumed with respect to the initial amount, the blowing of air is stopped, and the Si quality is 13.4%. 15 g of sodium silicate and 230 g of aluminum sulfate with an Al grade of 6% were added to the solution. Further, dilute sulfuric acid was added to adjust the pH of the solution to 5-9.
The magnetite particles thus obtained were washed and filtered by a conventional method, further dried, and then pulverized. Various characteristics of the obtained magnetic iron oxide 1 were measured. The results are shown in Table 1.

<Production Examples 2 to 12 of Magnetic Iron Oxide>
In Production Example 1 of the magnetic iron oxide, the amounts of titanyl sulfate, sodium silicate, and aluminum sulfate were appropriately changed, and in Steps 1 and 2, while monitoring the ratio of consumption of ferrous hydroxide, Step 1 Magnetic oxidation in the same manner as in Production Example 1 except that the timing of transition from step 2 to step 2 for adding titanyl sulfate to step 3 for adding aluminum sulfate to step 3 (consumption ratio of ferrous hydroxide) was finely adjusted. Iron 2-12 was obtained. Table 1 shows the results of measurement of various physical properties.

表１において
＊１ 磁性酸化鉄全体に占めるＴｉ成分の含有量（質量％）
＊２ 磁性酸化鉄全体に占めるＡｌ成分の含有量（質量％）
＊３ 磁性酸化鉄全体に占めるＳｉ成分の含有量（質量％）
＊４ 磁性酸化鉄をアルカリ水溶液に投入し、磁性酸化鉄に含まれるＡｌ成分を当該アルカリ水溶液で溶出したときに溶出されるＡｌ成分量の、当該磁性酸化鉄に含まれる全Ａｌ
成分量に対する割合（％）、及び、当該割合（％）と上記磁性酸化鉄全体に占めるＡｌ成分の含有量（質量％）の積で表される最表層のＡｌ量（質量％）
＊５ Ｆｅ元素溶解率１０質量％溶解液中に含まれるＡｌ成分量と、磁性酸化鉄をアルカリ水溶液に投入し、磁性酸化鉄に含まれるＡｌ成分を当該アルカリ水溶液で溶出したときに溶出されるＡｌ成分量との合計の、当該磁性酸化鉄に含まれる全Ａｌ成分量に対する割合の合計（％）
＊６ Ｆｅ元素溶解率１０質量％溶解液中に含まれる、Ｔｉ成分量のＴｉ元素換算値／Ａｌ成分量のＡｌ元素換算値の比
＊７ 磁性酸化鉄をアルカリ水溶液に投入し、磁性酸化鉄に含まれるＳｉ成分を当該アルカリ水溶液で溶出したときに溶出されるＳｉ成分量の、当該磁性酸化鉄に含まれる全Ｓｉ成分量に対する割合（％）
＊８ Ｆｅ元素溶解率１０質量％溶解液中に含まれる、Ｔｉ成分量のＴｉ元素換算値の、Ｓｉ成分量のＳｉ元素換算値に対する比（Ｔｉ成分量のＴｉ元素換算値／Ｓｉ成分量のＳｉ元素換算値）

In Table 1, * 1 Content of Ti component in the entire magnetic iron oxide (mass%)
* 2 Al component content (% by mass) in the total magnetic iron oxide
* 3 Content of Si component in the entire magnetic iron oxide (mass%)
* 4 Total Al contained in the magnetic iron oxide in the amount of Al component eluted when the magnetic iron oxide is added to the alkaline aqueous solution and the Al component contained in the magnetic iron oxide is eluted with the alkaline aqueous solution.
Al amount (% by mass) of the outermost layer represented by the product of the ratio (%) to the component amount, and the ratio (%) and the content (% by mass) of the Al component in the total magnetic iron oxide
* 5 Fe element dissolution rate 10% by mass The amount of Al component contained in the solution and magnetic iron oxide are added to the alkaline aqueous solution, and the Al component contained in the magnetic iron oxide is eluted with the alkaline aqueous solution. Sum of the proportion of the total amount of Al components to the total amount of Al components contained in the magnetic iron oxide (%)
* 6 Ratio of Fe element dissolution rate 10% by mass Ti component amount Ti element equivalent value / Al component amount Al element equivalent value * 7 Ratio of magnetic iron oxide to alkaline aqueous solution and magnetic iron oxide Of the amount of Si component eluted when the Si component contained in the solution is eluted with the alkaline aqueous solution to the total amount of Si component contained in the magnetic iron oxide (%)
* 8 Fe element dissolution rate 10% by mass The ratio of the Ti component amount of the Ti component amount to the Si element equivalent value of the Ti component amount (Ti component amount of Ti element amount / Si component amount) Si element equivalent value)

Examples of the method for preparing each material and the method for producing toner particles are shown below. Note that “parts” and “%” in the following formulations are based on mass unless otherwise specified.
<Synthesis of Amorphous Polyester Resin (1)>
-Dimethyl terephthalate 136 parts-44 parts by weight adipic acid-10 parts by weight trimellitic anhydride-2 parts adduct of bisphenol A-propylene oxide 304 parts-0.8 part by weight dibutyltin oxide 0.8 parts by weight And allowed to react at 170 ° C. for 4 hours. Furthermore, it was made to react at 200 degreeC under pressure reduction, water and methanol were removed, and the amorphous polyester resin (1) which is a nonlinear polyester resin was obtained.

<Synthesis of crystalline polyester resin (1)>
-Sebacic acid 100 mol%
・ 1,9-nonanediol 110mol%
・ Dibutyltin oxide 0.031mol%
The above material was placed in a flask purged with nitrogen, and 170 ° C. for 4 hours.
The reaction was carried out at 0 ° C. for 0.5 hours to obtain a crystalline polyester resin (1) having a melting point of 70 ° C.

<Binder resin fine particle dispersion (1)>
100 parts by mass of the amorphous polyester resin (1) was dissolved in 150 parts by mass of tetrahydrofuran. An ion in which 5 parts by mass of potassium hydroxide and 10 parts by mass of sodium dodecylbenzene-sulfonate were added as surfactants while stirring this tetrahydrofuran solution at 10,000 rpm for 2 minutes with a homogenizer (manufactured by IKA Japan: Ultra Tarax) at room temperature. 1000 parts by mass of exchange water was dropped. The mixed solution was heated to about 75 ° C. to remove tetrahydrofuran. Then, it diluted with ion-exchange water so that solid content might be 8%, and the binder resin fine particle dispersion (1) with a volume average particle diameter of 0.09 micrometer was obtained.

<Binder resin fine particle dispersion (2)>
In the preparation of the binder resin fine particle dispersion (1), the binder resin fine particle dispersion (2) was similarly obtained except that the amorphous polyester resin (1) was replaced with the crystalline polyester resin (1). Obtained.

<Magnetic iron oxide fine particle dispersion (1)>
-Magnetic iron oxide 1 49 parts by mass-Ionic surfactant (Neogen RK, Daiichi Kogyo Seiyaku) 1 part by mass-Ion-exchanged water 250 parts by mass-Glass beads (diameter 1 mm) 250 parts by mass Then, the mixture was dispersed for 3 hours with a paint shaker (manufactured by Toyo Seiki), and the glass beads were removed with a nylon mesh. Then, it diluted with ion-exchange water so that solid content might be 15%, and the magnetic iron oxide fine particle dispersion 1 was obtained.

<Magnetic iron oxide fine particle dispersions 2 to 12>
Magnetic iron oxide fine particle dispersions 2 to 12 were obtained in the same manner as in the preparation of the magnetic iron oxide fine particle dispersion 1, except that the magnetic iron oxides 2 to 12 were used instead of the magnetic iron oxide 1, respectively.

<Particle release agent fine particle dispersion (1)>
・ 200 parts by mass of polyethylene wax (PW850, manufactured by Toyo Petroleum) ・ 10 parts by mass of ionic surfactant (Neogen RK, Daiichi Kogyo Seiyaku) ・ 630 parts by mass of ion-exchanged water The mixture was stirred at 10,000 rpm for 2 minutes (IKA Japan: Ultra Tarax), and then cooled to 50 ° C. Then, it diluted with ion-exchange water so that solid content might be 20%, and mold release agent fine particle dispersion (1) was obtained.

<Charge control agent particle dispersion (1)>
20 parts by mass of a metal compound of di-alkyl salicylic acid (charge control agent, Bontron E-84, manufactured by Orient Chemical Industries)
・ Anionic surfactant 2 parts by mass (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen SC)
-Ion-exchange water 78 mass parts The above was mixed and the charge control agent particle dispersion liquid (1) stirred for 2 minutes at 10000 rpm with the homogenizer (IKA Japan make: Ultra Tarax) was obtained.

<Example 1>
[Production of Magnetic Toner 1]
(Production of magnetic toner particles (1))
-Binder resin fine particle dispersion (1) 80 parts by mass-Binder resin fine particle dispersion (2) 20 parts by mass-Magnetic iron oxide fine particle dispersion (1) 63 parts by mass-Release agent fine particle dispersion (1) 20 Part by mass / Charge control agent particle dispersion (1) 20 parts by mass The above was sufficiently mixed and dispersed in a round stainless steel flask using a homogenizer (manufactured by IKA Japan: Ultratarax). Thereafter, 0.4 parts by mass of polyaluminum chloride was added to this dispersion, and the dispersion operation was continued with a homogenizer (manufactured by IKA Japan: Ultra Tarax). Next, while stirring the flask in an oil bath for heating, the flask was heated to 50 ° C. and held for 60 minutes. In the subsequent melting step, after adding 3 parts by mass of an anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen SC), the stainless steel flask was sealed and stirring was continued using a magnetic seal. The mixture was heated to 100 ° C. and held for 5 hours. Then, after cooling, the reaction product was filtered, washed thoroughly with ion exchange water, and then dried to obtain magnetic toner particles (1).
(External addition process)
Henschel mixer with 0.7 parts by mass of hydrophobic silica (hexamethyldisilazane treatment) having a primary average particle size of 20 nm and 3.0 parts by mass of strontium titanate having a primary average particle size of 120 nm with respect to 100 parts by mass of magnetic toner particles 1 The magnetic toner 1 was obtained by mixing with FM-10B (manufactured by Mitsui Miike Chemical Industries).

(Evaluation of magnetic toner 1)
Table 2 shows the magnetization and weight average particle diameter (D4) as the characteristics of the magnetic toner 1.
The magnetic toner 1 was evaluated by the following method. Various performances of the magnetic toner 1 are shown in Table 3.

<Heat resistant storage stability>
A method for evaluating the heat-resistant storage stability of the magnetic toner will be described below. 3 g of magnetic toner was placed in a 100 mL polycup (manufactured by Sampratec), left in a thermostatic bath at 50 ° C. (± 0.5 ° C.) for 3 days, and then evaluated by touching it visually and with the belly of a finger. The smaller the change before and after being left, the better the heat resistant storage stability.
(Evaluation criteria)
A: No change in fluidity B: Fluidity slightly decreases C: Aggregates are generated but can be easily crushed

<Low temperature fixability>
A method for evaluating the low-temperature fixability of the magnetic toner will be described below.
For low-temperature fixability evaluation images, LaserJet 4515n (manufactured by Hewlett Packard) with a fixing unit removed is used, and the development contrast is adjusted so that the amount of magnetic toner on the paper is 0.90 ± 0.05 mg / cm ^2. Tip margin 10mm, width 200mm
A “solid unfixed image A” having a length of 30 mm was produced. The paper is A4 with a basis weight of 81.4 g / m ²
Paper CS814 (manufactured by Canon Marketing Japan Inc.) was used.
The fixing test was performed in a state where the fixing unit of LaserJet 4515n (manufactured by Hewlett Packard) was modified so that the fixing temperature and the paper passing speed could be manually set. The fixing temperature was determined by measuring the surface temperature of the upper roller of the fixing nip with a non-contact thermometer temperature hitter 3445 (manufactured by Hioki Electric). The sheet passing speed was measured with a fixing upper roller diameter and a digital tachometer HT-5100 (manufactured by Ono Sokki).
In a room temperature and normal humidity environment (23 ° C./60% RH), the sheet passing speed was set to 300 mm / sec, and the solid unfixed image A was passed through the fixing unit in steps of 5 ° C. from a fixing temperature of 100 ° C. to 180 ° C. . The portion 5 cm from the rear edge of the fixed image is rubbed 5 times with a soft thin paper (for example, “Dasper”, manufactured by Ozu Sangyo Co., Ltd.) while applying a load of 4.9 kPa, before and after rubbing. The image density reduction rate ΔD (%) was calculated by the following equation. The image density was measured with a reflection densitometer (Macbeth RD918).
The temperature at which ΔD (%) was less than 5% was determined as the fixing start temperature. The lower the fixing start temperature, the better the low-temperature fixability.
ΔD (%) = (image density before rubbing−image density after rubbing) × 100 / image density before rubbing (evaluation criteria)
A: Fixing start temperature is 120 ° C. or less B: Fixing start temperature is 125 ° C. to 145 ° C.
C: Fixing start temperature is 150 ° C. to 170 ° C.
D: Fixing start temperature is 175 ° C. or higher In addition, a magnetic toner left for 30 days in a high-temperature and high-humidity environment (32.5 ° C./80% RH) where fixing ability may be lowered was used for evaluation.

<Durability>
A method for evaluating the durability of the magnetic toner will be described below. 900 g of magnetic toner was filled in 5942x CRG (manufactured by Hewlett-Packard Company), and LaserJet 4515n (manufactured by Hewlett-Packard Company) was used in a room temperature and normal humidity environment (23 ° C./60% RH). First, after printing 999 sheets of images (durability image) with a printing area ratio of 4% in which a lattice pattern with a line width of 42 μm is arranged on the entire surface of A4 paper, and the charging of the magnetic toner in the cartridge is started,
A single solid image (density image) for density measurement is printed. The density of the image for density is measured with a reflection densitometer (Macbeth RD918) at five points and averaged to obtain D ₁ .
After 29999 sheets printed, it prints one density image, similarly to D _2. The ratio of the density of the 30,000th sheet to the density of the 1000th sheet (D ₂ / D ₁ ) was evaluated. The smaller D ₂ / D _{1, the} better the durability. As the paper, A4 paper CS814 (manufactured by Canon Marketing Japan Inc.) having a basis weight of 81.4 g / m ² was used.
For the evaluation, a magnetic toner that was left for 30 days in a high-temperature and high-humidity environment (32.5 ° C./80% RH) in which durability could be lowered was used.
(Evaluation criteria)
A: D ₂ / D ₁ is 0.90 or more and 1.00 or less B: D ₂ / D ₁ is 0.75 or more and less than 0.90 C: D ₂ / D ₁ is 0.60 or more and less than 0.75 D: D ₂ / D ₁ is less than 0.60

<Concentration>
The image density evaluation method will be described below. The evaluation of the image density is the value of D1 in the durability evaluation. The higher D1, the better. For the evaluation, a magnetic toner that was left for 30 days in a high-temperature and high-humidity environment (32.5 ° C./80% RH) in which the concentration could be lowered was used.

<Fog>
The evaluation method for fogging of magnetic toner will be described below. In the durability evaluation, the amplitude of the AC component of the developing bias was set at 1.8 kV at the end of 1000 sheets, two solid whites were printed, and the second fog was measured by the following method.
Using a reflection densitometer (reflectometer model TC-6DS manufactured by Tokyo Denshoku Co., Ltd.), the transfer material before and after image formation was measured. Was Dr, Ds-Dr was determined, and this was defined as fog. The lower the Ds-Dr, the less the fog and the better.

<Examples 2 to 4>
(Production of magnetic toner particles (2) to (4))
In the production of the magnetic toner particles (1), magnetic iron oxide 2 is used instead of magnetic iron oxide 1, magnetic iron oxide 3 is used instead of magnetic iron oxide 1, and magnetic iron oxide 4 is used instead of magnetic iron oxide 1. Similarly, magnetic toner particles (2), magnetic toner particles (3), and magnetic toner particles (4) were obtained. Thereafter, magnetic toners 2 to 4 having physical properties as shown in Table 2 were obtained in the same manner as in Example 1, and the same evaluation as in Example 1 was performed. The evaluation results are shown in Table 3.

<Example 5>
(Production of magnetic toner particles (5))
In the production of the magnetic toner particles (1), instead of the magnetic iron oxide 1, the mass parts of the magnetic iron oxide 5, the binder resin fine particle dispersion (1) and the binder resin fine particle dispersion (2) are 99 parts by mass and Magnetic toner particles (5) were obtained in the same manner except that the amount was 1 part by mass. Thereafter, a magnetic toner 5 having physical properties as shown in Table 2 was obtained in the same manner as in Example 1, and the same evaluation as in Example 1 was performed. The evaluation results are shown in Table 3.

<Example 6>
(Production of magnetic toner particles (6))
In the production of the magnetic toner particles (1), instead of the magnetic iron oxide 1, the mass parts of the magnetic iron oxide 6, the binder resin fine particle dispersion (1), and the binder resin fine particle dispersion (2) are 60 parts by mass and Magnetic toner particles (6) were obtained in the same manner except that the amount was 40 parts by mass. Thereafter, a magnetic toner 6 having physical properties as shown in Table 2 was obtained in the same manner as in Example 1, and the same evaluation as in Example 1 was performed. The evaluation results are shown in Table 3.

<Example 7>
(Magnetic toner particles (7)
In the production of the magnetic toner particles (1), in place of the magnetic iron oxide 1, the magnetic iron oxide 7, the binder resin fine particle dispersion (1) and the binder resin fine particle dispersion (2) have 50 parts by mass and 50 parts by mass, respectively. Magnetic toner particles (7) were obtained in the same manner except that the amount was 50 parts by mass. Thereafter, a magnetic toner 7 having physical properties as shown in Table 2 was obtained in the same manner as in Example 1, and the same evaluation as in Example 1 was performed. The evaluation results are shown in Table 3.

<Example 8>
(Production of magnetic toner particles (8))
In the production of the magnetic toner particles (1), instead of the magnetic iron oxide 1, the mass parts of the magnetic iron oxide 8, the binder resin fine particle dispersion (1) and the binder resin fine particle dispersion (2) are 49 parts by mass and Magnetic toner particles (8) were obtained in the same manner except that the amount was 51 parts by mass. Thereafter, a magnetic toner 8 having physical properties as shown in Table 2 was obtained in the same manner as in Example 1, and the same evaluation as in Example 1 was performed. The evaluation results are shown in Table 3.

<Example 9>
(Production of magnetic toner particles (9))
In the production of the magnetic toner particles (1), instead of the magnetic iron oxide 1, the mass parts of the magnetic iron oxide 9, the binder resin fine particle dispersion (1) and the binder resin fine particle dispersion (2) are set to 100 parts by mass, respectively. Magnetic toner particles (9) were obtained in the same manner except that the amount was 0 parts by mass. Thereafter, a magnetic toner 9 having physical properties as shown in Table 2 was obtained in the same manner as in Example 1, and the same evaluation as in Example 1 was performed. The evaluation results are shown in Table 3.

<Comparative Examples 1 and 2>
(Production of magnetic toner particles (10) to (11))
In the production of the magnetic toner particles (1), the mass parts of the magnetic iron oxides 10 to 11, the binder resin fine particle dispersion (1) and the binder resin fine particle dispersion (2) instead of the magnetic iron oxide 1 are each 100 masses. Magnetic toner particles (10) to (11) were obtained in the same manner except that the amount was 0 parts by mass and 0 parts by mass. Thereafter, in the same manner as in Example 1, magnetic toners 10 to 11 having physical properties as shown in Table 2 were obtained and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 3.

<Comparative Example 3>
(Production of magnetic toner particles (12))
In the production of the magnetic toner particles (1), instead of the magnetic iron oxide 1, the mass parts of the magnetic iron oxide 12, the binder resin fine particle dispersion (1) and the binder resin fine particle dispersion (2) are 40 parts by mass and Magnetic toner particles (12) were obtained in the same manner except that the amount was 60 parts by mass. Thereafter, in the same manner as in Example 1, a magnetic toner 12 having physical properties as shown in Table 2 was obtained, and the same evaluation as in Example 1 was performed. The evaluation results are shown in Table 3.

Claims (2)

A step of preparing a binder resin fine particle dispersion in which binder resin fine particles are dispersed in an aqueous medium;
Preparing a magnetic iron oxide fine particle dispersion in which magnetic iron oxide fine particles are dispersed in an aqueous medium;
Preparing a release agent fine particle dispersion in which release agent fine particles are dispersed in an aqueous medium;
An aggregation step of mixing the binder resin fine particle dispersion, the magnetic iron oxide fine particle dispersion, and the release agent fine particle dispersion to prepare an aggregated particle dispersion in which the aggregated particles are dispersed in an aqueous medium; and
A melting step in which the aggregated particles are melted / fused to obtain magnetic toner particles;
A method for producing magnetic toner particles having
The magnetic toner particles contain at least a binder resin, magnetic iron oxide particles , and a release agent ,
The binder resin contains as a main component at least polyester resin,
The magnetic iron oxide particles are
After 20 parts by mass of the magnetic iron oxide particles were dispersed in 80 parts by mass of isopropyl alcohol, it was allowed to stand, and after 10 minutes of standing in the isopropyl alcohol precipitation test in which the change with time of the precipitation volume of the magnetic iron oxide particles was measured. _VIPA is the precipitation volume of the magnetic iron oxide particles of
After dispersing 20 parts by mass of the magnetic iron oxide particles in 80 parts by mass of ethyl acetate, the mixture was allowed to stand, and after 10 minutes of standing in the ethyl acetate precipitation test in which the change with time of the precipitation volume of the magnetic iron oxide particles was measured. When the precipitation volume of the magnetic iron oxide particles is V _EtA and the total volume up to the liquid level of ethyl acetate is v _EtA ,
The ratio V _IPA / V _EtA between the V _IPA and V _EtA is, is 1.2 to 3.0,
The ratio V _EtA / v _EtA between the V _EtA and v _EtA is 0.2 to 0.7,
A method for producing magnetic toner particles . 2. The magnetic toner according to claim 1, wherein the polyester resin contains a crystalline polyester resin, and the content of the crystalline polyester resin is 1% by mass or more and 50% by mass or less with respect to the whole polyester resin. Particle production method .